阅读说明：本技术 伸缩装置及起重机 (Telescopic device and crane ) 是由 川渊直人 北山洋 增田尚隆 和田久典 川野贵史 于 2019-03-14 设计创作，主要内容包括：一种伸缩装置,使具有以能够伸缩的方式重叠的第一臂要素及第二臂要素的伸缩式臂伸缩,具备：第一液压源,喷出第一工作油；伸缩油缸,具有固定部以及相对于固定部能够移动的可动部,基于第一工作油的供给进行动作,使第一臂要素相对于第二臂要素在伸缩方向上移动；第二液压源,被设置于可动部,喷出第二工作油,是与第一液压源不同的液压源；第一连结机构,被设置于可动部,基于第二工作油的供给进行动作,对第一臂要素与可动部的连结状态和非连结状态进行切换；以及第二连结机构,被设置于可动部,基于第二工作油的供给进行动作,对第一臂要素与第二臂要素的连结状态和非连结状态进行切换。(A telescopic device for extending and contracting a telescopic arm having a first arm element and a second arm element which are overlapped in an extensible manner, comprising: a first hydraulic source that ejects first working oil; a telescopic cylinder having a fixed portion and a movable portion movable relative to the fixed portion, and operating based on the supply of the first working oil to move the first arm element relative to the second arm element in a telescopic direction; a second hydraulic source which is provided in the movable portion, discharges the second hydraulic oil, and is a different hydraulic source from the first hydraulic source; a first coupling mechanism provided in the movable portion and configured to operate based on supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the movable portion; and a second coupling mechanism provided in the movable portion and operating on the basis of the supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the second arm element.)

1. A telescopic device for extending and contracting a telescopic arm having a first arm element and a second arm element which are overlapped in an extensible manner, the telescopic device comprising:

a first hydraulic source that ejects first working oil;

a telescopic cylinder having a fixed portion and a movable portion movable relative to the fixed portion, and operating based on the supply of the first working oil to move the first arm element relative to the second arm element in a telescopic direction;

a second hydraulic source that is a different hydraulic source from the first hydraulic source, is provided in the movable portion, and discharges a second hydraulic oil;

a first coupling mechanism that is provided in the movable unit and operates based on supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the movable unit; and

and a second coupling mechanism that is provided in the movable portion and operates based on supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the second arm element.

2. The telescopic device as claimed in claim 1,

the second hydraulic pressure source has an oil tank, an electric motor, and a hydraulic pump driven by the electric motor.

3. The telescopic device as claimed in claim 2,

the second hydraulic pressure source further includes an accumulator that pressurizes and accumulates the second hydraulic oil discharged from the hydraulic pump,

the first and second coupling mechanisms operate based on the supply of the second hydraulic oil stored in the accumulator.

4. A telescopic device according to claim 3,

the hydraulic control device further includes a control unit that drives the electric motor when the hydraulic pressure in a line connected to the accumulator is smaller than a predetermined value.

5. The telescopic device as claimed in claim 4,

the control unit intermittently rotates the electric motor.

6. The telescopic device as claimed in claim 4,

the control unit is disposed on the movable unit.

7. A telescopic device according to any of claims 3 to 6,

the oil tank and the hydraulic pump are connected by a first pipe, the hydraulic pump and the electric motor are electrically connected, and the hydraulic pump and the accumulator are connected by a second pipe, whereby the oil tank, the hydraulic pump, the electric motor, and the accumulator are unitized.

8. A telescopic device according to any of claims 2 to 7,

the electric motor is supplied with electric power via a cable that is wound out from a reel in accordance with the movement of the movable portion.

9. A telescopic device according to any of claims 2 to 7,

the electric motor is supplied with electric power from a battery provided in the movable portion.

10. A telescopic device according to any of claims 1 to 9,

the second working oil is the same kind of oil as the first working oil.

11. A telescopic device according to any of claims 1 to 9,

the second working oil is a different kind of oil from the first working oil.

12. A telescopic device according to any of claims 1 to 11,

the hydraulic control device further includes a switching valve that can selectively switch between a first state in which the second hydraulic oil is supplied from the second hydraulic pressure source to the first coupling mechanism and a second state in which the second hydraulic oil is supplied from the second hydraulic pressure source to the second coupling mechanism.

13. The telescopic device as claimed in claim 12,

the switching valve is capable of selectively switching the first state, the second state, a third state and a fourth state, the third state being a state in which the second hydraulic oil is discharged from the first coupling mechanism, and the fourth state being a state in which the second hydraulic oil is discharged from the second coupling mechanism.

14. A telescopic device according to claim 12 or 13,

the switching valve is composed of a plurality of electromagnetic valves.

15. A crane is provided with:

a telescopic arm having a first arm element and a second arm element which are overlapped in a telescopic manner; and

a telescopic device according to any of claims 1 to 14.

Technical Field

The present invention relates to a telescopic device for extending and retracting a telescopic arm of a mobile crane, and a crane equipped with the telescopic device.

Background

As a telescopic device of a telescopic arm of a mobile crane, a telescopic device in which an arm element constituting the telescopic arm is extended and contracted by 1 stage at a time by a single telescopic cylinder (hydraulic cylinder) built in the telescopic arm has been put into practical use (hereinafter, this telescopic device is referred to as a "single cylinder telescopic device"). Since the single cylinder telescopic device has a single telescopic cylinder, the entire telescopic device can be reduced in weight, and the lifting performance of the mobile crane can be improved (see patent document 1, for example).

As characteristic configurations of the single cylinder telescopic device, an arm coupling mechanism, a coupling pin driving mechanism, and a cylinder/arm coupling mechanism described below can be given.

The arm coupling mechanism is provided on an arm element disposed on the inner side of a pair of arm elements disposed adjacent to each other. The arm coupling mechanism includes a coupling pin (hereinafter referred to as "B pin") for coupling (fixing) the inner arm element and the outer arm element. The arm coupling mechanism couples the adjacent inner arm element and the outer arm element (hereinafter referred to as "adjacent arm element") by inserting the B pin into a fixing hole provided at an appropriate position of the outer arm element. On the other hand, the arm connecting mechanism releases the connection between the adjacent arm elements by pulling out the pin B from the fixing hole. The arm connecting mechanism maintains the extended state of the telescopic arm extended by the single cylinder extension and retraction device. Such an arm connecting mechanism is an essential mechanism in a single cylinder extending and retracting device.

The connecting pin drive mechanism (hereinafter referred to as "B pin drive mechanism") is disposed in the movable portion of the telescopic cylinder. The B-pin drive mechanism moves the B-pin provided on the inner arm element among target adjacent arm elements (adjacent arm elements including the arm element to be extended and contracted). The B-pin drive mechanism shifts the state of the adjacent arm elements from the connected state to the disconnected state (also referred to as an unconnected state) or from the disconnected state to the connected state. The pin B driving mechanism and the arm connecting mechanism are the same mechanisms necessary for the single oil cylinder telescopic device. The B pin driving mechanism comprises a B pin oil cylinder for moving the B pin. The B pin cylinder is arranged in a narrow space of the movable part of the telescopic cylinder. Such a B-pin cylinder requires a relatively large output, and is therefore constituted by a hydraulic cylinder.

The cylinder/arm connecting mechanism is disposed on the movable portion of the telescopic cylinder. The cylinder/arm coupling mechanism has a coupling pin (hereinafter referred to as "C pin") for coupling the movable portion of the telescopic cylinder to a target arm element (arm element to be extended or retracted). The cylinder/arm coupling mechanism selectively couples the movable portion of the telescopic cylinder and the arm element by inserting the C pin into the coupling hole of the arm element to be extended and contracted. In addition, the cylinder/arm coupling mechanism releases the coupling between the movable portion of the telescopic cylinder and the arm element by pulling out the C pin from the coupling hole of the arm element which is symmetrical in terms of expansion and contraction. The cylinder/arm connecting mechanism is a mechanism necessary for a single cylinder extending and retracting device that extends and retracts all the arm elements by a single extending and retracting cylinder. The cylinder/arm connecting mechanism includes a C-pin driving mechanism such as a C-pin cylinder for moving the C-pin. The C-pin cylinder is disposed in a narrow space of the movable portion of the telescopic cylinder. Such a C-pin cylinder requires a relatively large output, and is therefore constituted by a hydraulic cylinder.

Fig. 10 is an example of a hydraulic circuit of a conventional hydraulic pressure supply unit 3 for supplying hydraulic oil to the B pin cylinder 1 and the C pin cylinder 2 used in the single cylinder telescopic device. The pin B cylinder 1 drives the pin B4. Such a B-pin cylinder 1 is a single-action hydraulic cylinder. The B pin cylinder 1 has a return compression coil spring 5 within the cylinder. The B pin cylinder 1 is supplied with working oil via a single hydraulic line 6. Further, the C-pin cylinder 2 drives the C-pin 7. Such a C-pin cylinder 2 is a single-acting cylinder. The C-pin cylinder 2 is returned to the reduction side by the pull coil spring 8 that biases the C-pin drive feeler lever 21. The C-pin cylinder 2 is supplied with working oil via a single hydraulic line 9.

The movable portion 11 of the telescopic cylinder is supplied with hydraulic oil from the fixed portion side 10 of the telescopic cylinder via a hydraulic hose 13. One end of the telescopic cylinder is supported by the fixed portion side 10 of the telescopic cylinder. Further, the hydraulic hose 13 is a single long hose that is wound off the hose reel 12. In the expansion/contraction process of the single cylinder expansion/contraction device, the B pin cylinder 1 and the C pin cylinder 2 are driven in a predetermined order. Therefore, the 1 st electromagnetic switching valve 14 is disposed on the fixed portion side 10 of the telescopic cylinder. Further, a 2 nd electromagnetic switching valve 15 and a 3 rd electromagnetic switching valve 16 are disposed in the movable portion 11 of the telescopic cylinder. The controller 18 disposed on the revolving frame (the fixed portion side 10 of the telescopic cylinder) sends control signals to the 2 nd electromagnetic switching valve 15 and the 3 rd electromagnetic switching valve 16 via the cable reel 17 and the control signal line 19.

Prior art documents

Patent document

Patent document 1 Japanese patent application laid-open No. 2002-332194

Disclosure of Invention

Problems to be solved by the invention

However, in the case of the telescopic arm telescopic device as described above, if the viscosity of the hydraulic oil increases at low temperatures, the pressure loss in the hydraulic hose 13 increases, and therefore the operations of the B pin cylinder 1 and the C pin cylinder 2 become slow. Therefore, the B pin driving mechanism and the cylinder/arm connecting mechanism may be delayed in operation, and the single cylinder telescopic device may not be normally operated. In order to avoid the operation delay at low temperature, the size of the hydraulic hose 13 needs to be increased to suppress the pressure loss in the hydraulic hose 13. However, if the size of the hydraulic hose 13 is increased, the hose reel 12 becomes larger. If hose reel 12 becomes large, it may be difficult to secure a space for racking hose reel 12 in the lift truck.

On the other hand, the following methods are also available: the telescopic cylinder is built in a feed line, and working oil is supplied from a fixed portion side 10 of the telescopic cylinder to a movable portion 11 of the telescopic cylinder through the feed line. However, the telescopic cylinder with the built-in oil feed pipe has a complicated internal structure and is difficult to manufacture. In addition, the telescopic cylinder built in the oil feed pipe cannot solve the problem of ensuring the operability at low temperatures. Further, the following techniques are known: the hydraulic oil pressurized by the operation of the telescopic cylinder is taken from the telescopic cylinder and accumulated in the hydraulic accumulator. However, in the case of such a technique, when the pressurized hydraulic oil is accumulated in the hydraulic accumulator, the hydraulic accumulator is affected by the operation cycle of the telescopic cylinder. The invention aims to provide a telescopic device which is not influenced by the action cycle of a telescopic oil cylinder.

Means for solving the problems

One aspect of the telescopic device of the present invention is a telescopic device for extending and contracting a telescopic arm having a first arm element and a second arm element that are overlapped to be capable of extending and contracting, the telescopic device including: a first hydraulic source that ejects first working oil; a telescopic cylinder having a fixed portion and a movable portion movable relative to the fixed portion, and operating based on the supply of the first working oil to move the first arm element relative to the second arm element in a telescopic direction; a second hydraulic source that is a different hydraulic source from the first hydraulic source, is provided in the movable portion, and discharges a second hydraulic oil; a first coupling mechanism provided in the movable portion and configured to operate based on supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the movable portion; and a second coupling mechanism provided in the movable portion and operating on the basis of the supply of the second hydraulic oil to switch between a coupled state and a non-coupled state of the first arm element and the second arm element.

One aspect of a crane according to the present invention includes: a telescopic arm having a first arm element and a second arm element which are overlapped in a telescopic manner; and the telescopic device.

Effects of the invention

According to the present invention, a telescopic device which is not affected by the operation cycle of the telescopic cylinder can be provided.

Drawings

Fig. 1 is a hydraulic circuit diagram of a hydraulic pressure supply unit in a telescopic device according to an embodiment of the present invention.

Fig. 2 is a sectional view of a 6-stage telescopic arm mounted with a telescopic device.

Fig. 3 is a sectional view a-a of fig. 2.

Fig. 4 is a view from B-B of fig. 3.

FIG. 5 is a control block diagram and hydraulic circuit for the telescoping device.

Fig. 6 is a display screen of the telescopic information display mechanism.

Fig. 7 is a view from direction D-D of fig. 2.

Fig. 8 is a view along direction C-C of fig. 3.

Fig. 9 is a diagram showing a lift truck having a telescopic device mounted thereon.

Fig. 10 shows an example of a conventional hydraulic circuit of the hydraulic pressure supply unit.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[ embodiment ]

A telescopic device according to an embodiment of the present invention will be described with reference to fig. 1.

Fig. 1 is a diagram showing an example of a hydraulic circuit of a hydraulic pressure supply unit 20 provided in a telescopic device. In the description of the hydraulic pressure supply unit 20 shown in fig. 1, the same components as those of the conventional hydraulic pressure supply unit 3 shown in fig. 10 will be described with the same reference numerals.

< Hydraulic pressure supply part >

As shown in fig. 1, the hydraulic pressure supply unit 20 includes a cylinder/arm coupling mechanism 64 and an arm coupling mechanism 70. The hydraulic pressure supply unit 20 includes a hydraulic unit 24, a 1 st electromagnetic switching valve 14, a 2 nd electromagnetic switching valve 15, a 3 rd electromagnetic switching valve 16, and the like.

< cylinder/arm connecting mechanism >

The cylinder/arm connecting mechanism 64 has a C-pin cylinder 2. The C-pin cylinder 2 is disposed in the movable portion 11 of the telescopic cylinder 43 (see fig. 2). The C-pin cylinder 2 moves the C-pin 7 to insert and remove the C-pin 7 into and from the target arm connecting hole. The cylinder/arm connecting mechanism 64 corresponds to an example of the first connecting mechanism. The first link mechanism operates based on the supply of the hydraulic oil (also referred to as second hydraulic oil) discharged from the hydraulic pressure supply unit 20, and switches between a connected state and a disconnected state between an arm element (for example, a second arm 52 shown in fig. 2) and the telescopic cylinder 43 to be moved.

Specifically, the C-pin cylinder 2 selectively couples the movable portion 11 of the telescopic cylinder 43 and the arm by inserting the C-pin 7 into a coupling hole of the arm. The C-pin cylinder 2 releases the connection between the movable portion 11 and the arm by pulling out the C-pin 7 from the arm connecting hole.

The C-pin 7 is urged to the coupling side by a pull coil spring 8. The C-pin cylinder 2 and the C-pin 7 are connected by a C-pin drive feeler lever 21. The C pin oil cylinder 2 is a single-action hydraulic oil cylinder. The C-pin cylinder 2 is supplied with hydraulic pressure from a hydraulic unit 24 (specifically, a hydraulic accumulator 31) described later via a hydraulic line 9 and extends.

As a result, the C-pin cylinder 2 moves the C-pin 7 to the release side. If the hydraulic pressure supply to the hydraulic line 9 is cut off, the C-pin cylinder 2 is contracted by the urging force of the pull coil spring 8. As a result, the C-pin 7 moves to the coupling side due to the urging force of the pull coil spring 8.

< arm connecting mechanism >

The arm connecting mechanism 70 includes a B-pin cylinder 1. The B pin cylinder 1 is disposed in the movable portion 11 of the telescopic cylinder 43. The B-pin cylinder 1 moves the B-pin 4 of the target arm, thereby connecting the adjacent pair of arms to each other. The arm coupling mechanism 70 corresponds to an example of the second coupling mechanism. The second coupling mechanism operates based on the supply of the hydraulic oil (also referred to as second hydraulic oil) discharged from the hydraulic pressure supply unit 20, and switches between a coupled state and a non-coupled state between the first arm element (for example, the second arm 52 shown in fig. 2) and the second arm element (for example, the base arm 51).

Further, the B pin cylinder 1 is urged to the shortening side by a compression coil spring 5 built in the B pin cylinder 1. The pin B oil cylinder 1 is a single-action hydraulic oil cylinder. The B pin 4 is urged to the fixed side by a compression coil spring 22.

The B pin cylinder 1 and the B pin 4 are connected by a B pin drive feeler lever 74. When the movable portion 11 of the telescopic cylinder 43 moves alone, the connection between the B-pin driving lever 74 and the B-pin 4 can be released. The B pin cylinder 1 is supplied with hydraulic pressure from a hydraulic unit 24 (specifically, a hydraulic accumulator 31) described later via a single hydraulic line 6 and extends.

The extended B-pin cylinder 1 moves the B-pin 4 to the release side. If the hydraulic pressure supply to the hydraulic line 6 is cut off, the B-pin cylinder 1 is contracted by the urging force of the compression coil spring 5. As a result, the B pin 4 is driven to the fixed side by the urging force of the compression coil spring 22.

< Hydraulic Unit >

As shown in fig. 1, the hydraulic unit 24 is mounted on the movable portion 11 of the telescopic cylinder 43. The hydraulic unit 24 includes an electric motor 25, a hydraulic pump 26, an oil tank 27, a hydraulic accumulator 31, a hydraulic pressure sensor 34, and the like.

The hydraulic unit 24 has a discharge line 30 and a return line 32. As an example of such a hydraulic unit 24, each element constituting the hydraulic unit 24 is disposed in a housing (not shown) and unitized.

The respective elements constituting the hydraulic unit 24 are connected or electrically connected to each other in a state in which the working oil can flow. The hydraulic unit 24 corresponds to one example of the second hydraulic source. The hydraulic oil discharged from the hydraulic unit 24 corresponds to one example of the second hydraulic oil.

The electric motor 25 drives the hydraulic pump 26 under the control of a control unit (specifically, the controller 35). The hydraulic pump 26, if driven by the electric motor 25, sucks up the hydraulic oil stored in the hydraulic oil tank 27 from the suction port. Then, the hydraulic pump 26 discharges the sucked up hydraulic oil from the discharge port. The hydraulic oil discharged from the discharge port of the hydraulic pump 26 flows into the discharge line 30 through the check valve 28 and the high-pressure filter 29. The pipe connecting the motor hydraulic pump 26 and the hydraulic oil tank 27 corresponds to an example of the first pipe.

A relief valve 33 is provided between the discharge line 30 and the return line 32. The relief valve 33 determines the maximum pressure of the discharge line 30. That is, if the pressure in the discharge line 30 is greater than a predetermined threshold value, the relief valve 33 fluidly connects the discharge line 30 and the return line 32, and causes the hydraulic oil in the discharge line 30 to flow to the return line 32.

The hydraulic accumulator 31 is connected to the discharge line 30. The hydraulic accumulator 31 absorbs the hydraulic oil in the discharge line 30 and accumulates the pressure. The conduit connecting the hydraulic accumulator 31 and the hydraulic pump 26 corresponds to an example of the second conduit. Furthermore, the second conduit may contain a valve (e.g. check valve 28), a filter (e.g. high pressure filter 29).

The hydraulic pressure sensor 34 is connected to the ejection line 30. The hydraulic pressure sensor 34 measures the pressure in the discharge line 30.

As shown in fig. 1, the 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, and the 3 rd electromagnetic switching valve 16 are disposed in the movable portion 11 of the telescopic cylinder 43. The 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, and the 3 rd electromagnetic switching valve 16 are connected in series.

The 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, and the 3 rd electromagnetic switching valve 16 constitute a switching valve unit. The switching valve unit switches between a state in which the hydraulic oil is supplied from the hydraulic unit 24 to the B pin cylinder 1 or the C pin cylinder 2 and a state in which the hydraulic oil in the B pin cylinder 1 or the hydraulic oil in the C pin cylinder 2 is returned to the tank 27, in accordance with the states of the 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, and the 3 rd electromagnetic switching valve 16. The switching valve unit corresponds to an example of the switching valve.

The state in which the hydraulic oil is supplied from the hydraulic unit 24 to the B pin cylinder 1 is referred to as a first supply state of the hydraulic pressure supply unit 20 (hereinafter, also referred to simply as a first supply state). The state in which the hydraulic oil is supplied from the hydraulic unit 24 to the C-pin cylinder 2 is referred to as a second supply state of the hydraulic pressure supply unit 20 (hereinafter, also referred to simply as a second supply state). The state in which the hydraulic oil in the B-pin cylinder 1 is returned to the tank 27 is referred to as a first discharge state of the hydraulic pressure supply unit 20 (hereinafter, also referred to simply as a first discharge state). The state in which the hydraulic oil in the C-pin cylinder 2 is returned to the tank 27 is referred to as a second discharge state of the hydraulic pressure supply unit 20 (hereinafter, also referred to simply as a second discharge state).

The 1 st electromagnetic switching valve 14 is a 3-port 2-position switching valve. The 1 st electromagnetic switching valve 14 is connected to a discharge line 30, a return line 32, and a first connection line connecting the 1 st electromagnetic switching valve 14 and the 2 nd electromagnetic switching valve 15.

Specifically, the 1 st port of the 1 st electromagnetic switching valve 14 is connected to an end of the discharge line 30. An end of the return line 32 is connected to the 2 nd port of the 1 st electromagnetic switching valve 14. Further, an end of the first connection line is connected to the 3 rd port of the 1 st electromagnetic switching valve 14.

The 1 st electromagnetic switching valve 14 communicates the 2 nd port with the 3 rd port in the first state (non-energized state). In the first state of the 1 st electromagnetic switching valve 14, the hydraulic oil that flows from the 2 nd electromagnetic switching valve 15 to the 1 st electromagnetic switching valve 14 returns to the tank 27.

The 1 st electromagnetic switching valve 14 communicates the 1 st port with the 3 rd port in the second state (energized state). In the second state of the 1 st electromagnetic switching valve 14, the hydraulic oil that flows into the 1 st electromagnetic switching valve 14 from the hydraulic unit 24 is supplied to the 2 nd electromagnetic switching valve 15.

The 2 nd electromagnetic switching valve 15 is a 2 nd port 2 position switching valve. The 2 nd electromagnetic switching valve 15 is provided between the 1 st electromagnetic switching valve 14 and the 3 rd electromagnetic switching valve 16. Specifically, the 1 st port of the 2 nd electromagnetic switching valve 15 is connected to an end of the first connection line.

Further, an end of a second connection line connecting the 2 nd electromagnetic switching valve 15 and the 3 rd electromagnetic switching valve 16 is connected to the 2 nd port of the 2 nd electromagnetic switching valve 15.

The 2 nd electromagnetic switching valve 15 communicates the 1 st port with the 2 nd port in the first state (non-energized state). In the first state of the 2 nd electromagnetic switching valve 15, the working oil flows between the first connecting line and the second connecting line.

The 2 nd electromagnetic switching valve 15 blocks the 1 st port and the 2 nd port in the second state (energized state). In the second state of the 2 nd electromagnetic switching valve 15, the flow of the hydraulic oil is blocked between the first connecting line and the second connecting line.

The 3 rd electromagnetic switching valve 16 is a 3-port 2-position switching valve. The 3 rd electromagnetic switching valve 16 is provided between the B pin cylinder 1 and the C pin cylinder 2 and the 2 nd electromagnetic switching valve 15.

Specifically, the 1 st port of the 3 rd electromagnetic switching valve 16 is connected to an end of the second connection line.

Further, an end of a third connection line connecting the 3 rd electromagnetic switching valve 16 and the B pin cylinder 1 is connected to the 2 nd port of the 3 rd electromagnetic switching valve 16. Further, an end of a fourth connection line connecting the 3 rd electromagnetic switching valve 16 and the C-pin cylinder 2 is connected to the 3 rd port of the 3 rd electromagnetic switching valve 16.

The 3 rd electromagnetic switching valve 16 communicates the 1 st port with the 3 rd port in the first state (non-energized state). In the first state of the 3 rd electromagnetic switching valve 16, the working oil flowing from the 2 nd electromagnetic switching valve 15 to the 3 rd electromagnetic switching valve 14 is supplied to the C-pin cylinder 2.

The 3 rd electromagnetic switching valve 16 communicates the 1 st port with the 2 nd port in the second state (energized state). That is, in the second state of the 3 rd electromagnetic switching valve 16, the working oil flowing from the 2 nd electromagnetic switching valve 15 to the 3 rd electromagnetic switching valve 14 is supplied to the B pin cylinder 1.

The following description deals with the relationship between the states of the 1 st, 2 nd, and 3 rd electromagnetic switching valves 14, 15, and 16 and the first supply state, the second supply state, the first discharge state, and the second discharge state.

In the first supply state, the 1 st electromagnetic switching valve 14 is in the second state (energized state), the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state), and the 3 rd electromagnetic switching valve 16 is in the second state (energized state).

In the second supply state, the 1 st electromagnetic switching valve 14 is in the second state (energized state), the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state), and the 3 rd electromagnetic switching valve 16 is in the first state (non-energized state).

In the first discharge state, the 1 st electromagnetic switching valve 14 is in the first state (non-energized state), the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state), and the 3 rd electromagnetic switching valve 16 is in the second state (energized state).

In the second discharge state, the 1 st electromagnetic switching valve 14 is in the first state (non-energized state), the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state), and the 3 rd electromagnetic switching valve 16 is in the first state (non-energized state).

The controller 35 is disposed on a turntable (a fixed portion side of the telescopic cylinder 43) of the crane truck. The electric motor 25 is connected to the controller 35 via a cable reel 37 and a power line 38 wound around the cable reel 37. The power line 38 corresponds to an example of a cable. The electric power line 38 is unwound from the cable reel 37 in accordance with the movement of the cylinder tube 44 (movable portion, see fig. 2) of the telescopic cylinder 43.

The hydraulic pressure sensor 34, the 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, and the 3 rd electromagnetic switching valve 16 are connected to the controller 35 via a cable reel 37 and control signal lines 39, 40, 41, and 42.

The hydraulic unit 24 of the hydraulic pressure supply unit 20 (see fig. 1) functions as follows. The hydraulic pump 26 is rotated by the electric motor 25. The hydraulic pump 26 draws the hydraulic oil from the hydraulic oil tank 27. The hydraulic pump 26 discharges the hydraulic oil to the discharge line 30 via the check valve 28 and the high-pressure filter 29. The hydraulic oil in the discharge line 30 is absorbed by the hydraulic accumulator 31 and accumulates pressure.

If the pressure of the discharge line 30 is higher than a set pressure (also referred to as a first predetermined pressure), the relief valve 33 opens an internal passage to allow the hydraulic oil in the discharge line 30 to flow out to the return line 32. That is, the relief valve 33 is in the open state when the pressure of the discharge line 30 is higher than the first predetermined pressure. The relief valve 33 is closed when the pressure in the discharge line 30 is equal to or lower than a first predetermined pressure.

The hydraulic pressure sensor 34 constantly measures the pressure in the discharge line 30. The hydraulic pressure sensor 34 sends a detection signal to the controller 35. The discharge pipe 30 corresponds to an example of a pipe connected to the accumulator.

If the pressure in the discharge line 30 rises to the upper limit set pressure of the relief valve 33, the controller 35 stops the transmission of electric power to the electric motor 25. Then, the electric motor 25 stops rotating. As a result, the pressure rise in the discharge line 30 and the hydraulic accumulator 31 stops.

The hydraulic oil in the discharge line 30 and the hydraulic accumulator 31 is sealed by the 1 st electromagnetic switching valve 14 and the check valve 28 to maintain the pressure.

If the hydraulic oil accumulated in the hydraulic accumulator 31 is consumed by the operations of the B pin cylinder 1 and the C pin cylinder 2, the pressure of the discharge line 30 decreases. The controller 35 supplies electric power to the electric motor 25 if the pressure of the discharge pipe 30 is lower than a lower limit set pressure (also referred to as a second predetermined pressure). Then, the hydraulic pump 26 is rotated by the electric motor 25. As a result, the hydraulic oil discharged from the hydraulic pump 26 flows into the discharge line 30, and the pressure in the discharge line 30 increases.

As described above, the hydraulic pump 26 is intermittently rotated by the hydraulic pressure sensor 34 and the controller 35 that monitor the pressure in the discharge line 30. Thus, the pressure of the hydraulic oil in the discharge line 30 and the hydraulic accumulator 31 is always maintained at a pressure equal to or higher than the lower limit set pressure (second predetermined pressure) and equal to or lower than the upper limit set pressure (first predetermined pressure).

As described above, the hydraulic unit 24 can constantly supply the hydraulic pressure for driving the B pin cylinder 1 and the C pin cylinder 2. The lower limit setting pressure and the upper limit setting pressure are selected to be sufficient pressures required to drive the B pin cylinder 1 and the C pin cylinder 2.

The hydraulic pressure supply unit 20 of the present invention includes a hydraulic unit 24 in the movable portion 11 of the telescopic cylinder 43. The hydraulic unit 24 does not require a long hydraulic line such as a hose reel or a feed pipe in the telescopic cylinder in order to supply hydraulic pressure to the B pin cylinder 1 and the C pin cylinder 2. Therefore, the operability at low temperatures of the B pin cylinder 1 and the C pin cylinder 2 is improved.

In addition, a large and heavy hose reel is not required, and therefore the frame-mounting performance of the lift truck is improved. And a complicated and difficult-to-manufacture telescopic cylinder such as a telescopic cylinder with a built-in oil delivery pipe is not required.

The pressure accumulation in the hydraulic unit 24 to the hydraulic accumulator 31 is independent of the extension and contraction process of the single cylinder extension and contraction device. Therefore, the control (operation process) of the single cylinder telescopic device is not related to the control of the pressure accumulation of the hydraulic accumulator 31. That is, the control degree of freedom of the single cylinder telescopic device is high.

The hydraulic circuit (also referred to as a first hydraulic circuit, see fig. 1) of the hydraulic pressure supply unit 20 is a circuit independent from the hydraulic circuit (also referred to as a second hydraulic circuit) of the entire lift truck. The second hydraulic circuit may be understood as a hydraulic circuit including the telescopic cylinder hydraulic pressure supply portion 105 (see fig. 5). The first hydraulic circuit and the second hydraulic circuit are provided as mutually independent hydraulic circuits. That is, the first hydraulic circuit and the second hydraulic circuit are not connected by a pipe or the like.

Therefore, the possibility that dirt enters the hydraulic circuit of the hydraulic pressure supply unit 20 from the outside is low. Since the hydraulic circuit of the hydraulic pressure supply unit 20 is independent of the hydraulic circuit of the entire lift truck, a dedicated oil type can be used as the hydraulic oil of the hydraulic pressure supply unit 20. In other words, the type of oil used in the hydraulic pressure supply unit 20 may be different from the type of oil used in the hydraulic circuit of the entire lift truck.

Further, since the entire hydraulic pressure supply unit 20 is integrally mounted on the movable unit 11 of the telescopic cylinder 43, the entire hydraulic pressure supply unit 20 can be modularized.

The pin B cylinder 1 and the pin C cylinder 2 intermittently operate during the telescopic operation of the single cylinder telescopic device. Since the size of the B pin cylinder 1 and the size of the C pin cylinder 2 are small, the amount of oil supplied from the hydraulic pressure supply unit 20 is small. Therefore, the electric motor 25, the hydraulic pump 26, the hydraulic accumulator 31, and the like constituting the hydraulic unit 24 can be downsized.

In order to cope with the failure, the hydraulic unit 24 may be provided with a plurality of electric motors 25 and a plurality of hydraulic pumps 26. In order to cope with the case where the power supply line is disconnected, a plurality of power supply lines may be provided to connect the controller 35 and the hydraulic pressure supply unit 20. Further, a battery for supplying power to the electric motor 25 may be provided in the movable portion 11 of the telescopic cylinder 43. The number of the batteries may be either single or plural.

In the present embodiment, an example in which the controller 35 that controls the entire single cylinder telescopic device controls the electric motor 25 of the hydraulic unit 24 is described. That is, in the present embodiment, the control unit that controls the single cylinder telescopic device and the control unit that controls the electric motor 25 of the hydraulic unit 24 are common control units.

As an example, a controller dedicated to the electric motor 25 may be disposed inside the hydraulic unit 24. In other words, a control unit for controlling the electric motor 25 may be provided separately from the control unit for controlling the single cylinder telescopic device. The control unit of the electric motor 25 may be unitized with the hydraulic unit 24.

The overall configuration of the telescopic device according to the present embodiment will be described with reference to fig. 2. Fig. 2 is a sectional view showing the overall configuration of the telescopic device according to the present embodiment. In fig. 2, a base end portion of a telescopic device mounted on the 6-stage telescopic arm 50 in a fully contracted state is shown in a cross section along the longitudinal direction of the telescopic cylinder 43. The telescopic device according to the present embodiment does not need to include all the elements shown in fig. 2.

As shown in fig. 2, the telescopic arm 50 includes intermediate arms 52 to 55 (a second arm 52, a third arm 53, a fourth arm 54, and a fifth arm 55 in this order from the outside) and a top arm 56, which are combined in a telescopic manner in a base arm 51. The top arm 56 is disposed innermost in the internal space of the base arm 51. Such a telescopic arm 50 has a housing space therein.

The base arm 51 corresponds to an example of the second arm element. In the case where the base arm 51 corresponds to an example of the second arm element, an intermediate arm (the second arm 52 in the present embodiment) disposed adjacent to the inner side of the base arm 51 corresponds to an example of the first arm element.

In addition, when the second arm 52 corresponds to an example of the second arm element, the third arm 53 corresponds to an example of the first arm element. When the third arm 53 corresponds to an example of the second arm element, the fourth arm 54 corresponds to an example of the first arm element. In the case where the fourth arm 54 corresponds to an example of the second arm element, the fifth arm 55 corresponds to an example of the first arm element. Further, in the case where the fifth arm 55 corresponds to an example of the second arm element, the top arm 56 corresponds to an example of the first arm element.

The telescopic cylinder 43 is provided in the housing space of the telescopic arm 50. The telescopic cylinder 43 has a cylinder tube 44 and a cylinder rod 46. The cylinder tube 44 corresponds to an example of a movable portion (also referred to as a movable-side member) of the telescopic cylinder. The cylinder rod 46 corresponds to an example of a fixed portion (also referred to as a fixed-side member) of the telescopic cylinder. The cylinder tube 44 may correspond to an example of a fixed-side member of the telescopic cylinder. In this case, the cylinder rod 46 may correspond to an example of a movable-side member of the telescopic cylinder.

The telescopic cylinder 43 extends and contracts under the control of the controller 35. Specifically, if the hydraulic oil is supplied from the oil tank T (see fig. 5) into the cylinder tube 44 under the control of the controller 35, the cylinder tube 44 moves in a direction (hereinafter referred to as an extension direction) in which the entire telescopic cylinder 43 extends with respect to the cylinder rod 46. In other words, the telescopic cylinder 43 extends if supplied with the hydraulic oil under the control of the controller 35.

On the other hand, if the hydraulic oil inside the cylinder tube 44 is discharged under the control of the controller 35, the cylinder tube 44 moves in a direction (hereinafter referred to as a retraction direction) in which the entire telescopic cylinder 43 is retracted with respect to the cylinder rod 46. In other words, the telescopic cylinder 43 contracts if the working oil is discharged under the control of the controller 35.

The hydraulic unit 24 is mounted on the cylinder tube 44. Specifically, the hydraulic unit 24 is fixed to the outer peripheral surface of the cylinder tube 44. The hydraulic unit 24 includes the electric motor 25 and the hydraulic pump 26 described above.

The cable reel 37 is rotatably provided at the base arm base end portion 51 a. The cable 60 is wound around the cable reel 37. The cable 60 includes the power line 38, control signal lines 39, 40, 41, and 42 (see fig. 1), and the like. The cable 60 can be pulled out from the cable reel 37.

The cable 60 is connected to the support 61 of the cylinder rod side end 45. The length detector 62 (see fig. 2) is provided at the base arm end 51 a. The wire 63 pulled out from the length detector 62 is connected to the support 61 of the cylinder rod side end 45.

Next, referring to fig. 3, the cylinder/arm connecting mechanism 64 in the telescopic device will be described. Fig. 3 is a sectional view a-a of fig. 2. Fig. 3 shows a case where the cylinder/arm coupling mechanism 64 is positioned in a coupling hole 56b provided in the boom base end portion 56 a. As shown in fig. 3, the second arm base end 52a, the third arm base end 53a, the fourth arm base end 54a, and the fifth arm base end 55a are also provided with coupling holes, respectively, in the same manner as the top arm base end 56 a.

As shown in fig. 3, the cylinder/arm connecting mechanism 64 includes the C-pin cylinder 2, the C-pin 7, the C-pin drive contact lever 21, and the like.

The C-pin cylinder 2 is provided at the cylinder bore rod side end portion 45. The C pin 7 is connected to the C pin cylinder 2 via a C pin drive trolley 21. The C-pin 7 is slidably attached to a C-pin receiving hole 66 of the trunnion member 65 constituting the cylinder rod side end portion 45.

The C-pin 7 is insertable into and removable from the coupling holes 52b to 56b provided in the arm base end portions 52a to 56a (in fig. 3, the coupling hole 56b provided in the top arm base end portion 56 a).

The C-pin 7 and the C-pin drive trolley 21 are provided in a pair on the left and right of the telescopic cylinder 43. The C-pin drive lever 21 is supported by a support (not shown) integrally formed above the trunnion member 65 via a pin 67. The C-pin drive trolley 21 can swing.

One end of the C-pin drive trolley 21 is connected to the C-pin 7. The C-pin 7 is urged to the coupling side by the pull coil spring 8 via the C-pin drive feeler lever 21.

Referring to fig. 3 and 4, the arm connecting mechanism 70 in the telescopic device will be described. Fig. 3 is a sectional view a-a of fig. 2. Fig. 4 is a view from B-B of fig. 3. Fig. 3 and 4 show an arm coupling mechanism 70 at a fixed portion of the top arm 56 and the fifth arm 55.

As shown in fig. 3 and 4, the arm connecting mechanism 70 includes a B pin driving mechanism 73, a B pin 56d, a compression coil spring 22, and the like.

The B pin 56d is a fixing pin for fixing the top arm 56 and the fifth arm 55. The B pins 56d are provided in a pair on the left and right. Similarly, a pair of a B pin 52d of the second arm 52, a B pin 53d of the third arm 53, a B pin 54d of the fourth arm 54, and a B pin 55d of the fifth arm 55 are provided on the left and right sides of the second arm base end 52a, the third arm base end 53a, the fourth arm base end 54a, and the fifth arm base end 55a, respectively (see fig. 2).

The fifth arm 55 has a fixing hole 55f on a side surface through which the B pin 56d is inserted. The fixing holes 55f are provided in plural in the longitudinal direction in accordance with the extended length of the top arm 56. The arrangement of the fixing holes is substantially the same in the other arms (the base arm 51, the second arm 52, the third arm 53, and the fourth arm 54).

In the description of the overall configuration of the telescopic device, the B pins corresponding to the respective arms are described as the B pins 52d to 56d, but the same as the B pin 4 described in fig. 1. That is, in fig. 1, only the B pin corresponding to the 1-stage arm is illustrated for the purpose of explaining the outline of the hydraulic pressure supply unit 20.

The B pin 56d is slidably attached to a B pin accommodating member 56e of the top arm base end portion 56 a. The B pin 56d is insertable into and removable from a fixing hole 55f provided in a side surface of the fifth arm 55. The B pin 56d is urged to the fixed side by a compression coil spring 22 arranged at an outer peripheral portion of the B pin 56 d.

The B pin 56d has a coupling member 72 at an inner end. The connecting member 72 has a box shape with a portion opened. The coupling member 72 can be coupled to the B-pin driving link 74 via a roller 75 of the B-pin driving mechanism 73.

The B-pin driving mechanism 73 includes a B-pin cylinder 1, a B-pin driving feeler lever 74, and a roller 75. The B-pin drive contact rod 74 is supported swingably by a support 76 provided at the cylinder rod side end portion 45 (the movable portion 11 of the telescopic cylinder 43). The B pin drive levers 74 are provided in a pair on the left and right.

The roller 75 is rotatably supported by one end of the B-pin drive lever 74. The rod-side end portion and the cylinder-side end portion of the B-pin cylinder are supported by the other end of the B-pin drive feeler lever 74. Fig. 4 shows a state in which the roller 75 is fitted into the coupling member 72 and the B pin 56d of the top arm 56 and the B pin drive mechanism 73 are coupled.

Since the entire B-pin drive mechanism 73 is configured integrally with the cylinder rod side end portion 45 shown in fig. 2, the B-pin drive mechanism 73 can drive the selected B-pin in a state where the roller 75 is positioned in the coupling member 72 corresponding to the B-pin selected from the B-pins 52d to 56d provided at the base end portions 52a to 56a of the respective arms in accordance with the expansion and contraction of the telescopic cylinder 43.

The connecting members 72 provided at the inner ends of the B pins 52d to 56d have a box shape with a partially open end. Therefore, when the telescopic cylinder 43 performs the telescopic operation, the B-pin driving feeler lever 74 passes through the opening portion of the coupling member 72 of the non-driven B-pin.

Next, a control module and a hydraulic circuit of the telescopic device according to the present embodiment will be described with reference to fig. 5. As shown in fig. 5, the telescopic device includes a telescopic operation mechanism 80, a telescopic state detection mechanism 90, a controller 35, a hydraulic pressure supply unit 20, and a telescopic cylinder hydraulic pressure supply unit 105.

The telescopic operation mechanism 80 includes a telescopic operation lever 81, a final arm state input mechanism 82, and a telescopic information display mechanism 83.

The telescopic operation lever 81 converts the lever operation direction and the operation amount of the telescopic operation into electric signals and outputs the electric signals to the controller 35.

The final arm state input mechanism 82 is used to input a target extension state (final arm state) after the telescopic operation when the telescopic arm 50 is extended and contracted. The final arm state input mechanism 82 is operated integrally with a telescopic information display mechanism 83 described later. The operation signal of the final arm state input mechanism 82 is output to the controller 35.

The telescopic information display means 83 graphically displays information related to the operation of the telescopic device based on a display control signal from the controller 35.

Fig. 6 shows an example of a display screen 84 of the telescopic information display means 83. The contents of the display screen 84 can be switched. On the display screen 84, the arm conditions when the telescopic arm 50 is extended and contracted are displayed.

The arm condition indicates an arm state after the extension of the telescopic arm 50, and the extension length 85 of the telescopic arm 50 is associated with the extension ratio 86 of each arm segment.

On the display screen 84, a plurality of arm conditions are displayed. The operator can select a desired arm condition by moving the frame cursor 88 up and down by operating the forward/return key of the final arm state input mechanism 82 on the display screen 84.

For example, the operator can input the arm condition to the controller 35 by moving the frame cursor 88 to the row of the target arm condition and then operating the set key of the final arm state input mechanism 82. In fig. 6, the selected arm condition is shown by circle mark 87.

The telescopic state detection means 90 has the following specific detection means. That is, the telescopic state detecting means 90 includes an arm base end position detecting means 91, a cylinder length detecting means 92, a C pin state detecting means 93, and a B pin state detecting means 94.

The arm base end position detection mechanism 91 detects which arm base end the cylinder/arm coupling mechanism 64 is located at, and outputs a detection signal to the controller 35.

The cylinder length detection means 92 detects the cylinder length of the telescopic cylinder 43 and outputs a detection signal to the controller 35.

The controller 35 acquires a standard telescopic length set in accordance with the position of the fixing hole of the arm coupling mechanism 70 based on the detection value of the cylinder length detection mechanism 92. The controller 35 sets the acquired standard extension/contraction length to the extension/contraction length in the arm extension/contraction step. The specification expansion/contraction length may be stored in a storage unit (not shown).

The C-pin state detection means 93 detects the state of the C-pin 7 driven by the cylinder/arm connection means 64, and outputs a detection signal to the controller 35.

The B-pin state detection means 94 detects the state of the B-pins 52d to 56d driven by the B-pin drive means 73, and outputs a detection signal to the controller 35.

Fig. 7 shows a specific example of the arm proximal end position detection mechanism 91. Fig. 7 is a view from direction D-D of fig. 2. In fig. 7, the arm base end position detection means 91 is constituted by proximity switches 95 to 99.

The proximity switches 95 to 99 are attached to the cylinder rod side end 45 (trunnion member 65) of the telescopic cylinder 43 via the supports 100 and 101.

The proximal end 56a of the tip arm is provided with a detection piece 56g at a position corresponding to the proximity switch 95. Fig. 7 shows a state in which the proximity switch 95 detects the detection piece 56g of the proximal end portion 56a of the tip arm.

Similarly, detection pieces 52g to 55g are provided at positions corresponding to the proximity switches 96 to 99, respectively, on the base end portions 52a to 55a of the other arms.

The controller 35 can determine the arm connecting hole to which the C pin 7 of the cylinder/arm connecting mechanism 64 is connected, based on which of the proximity switches 95 to 99 detects the detection pieces 52g to 56 g.

The cylinder length detection mechanism 92 is constituted by, for example, a length detector 62 attached to the base arm base end 51a on the fixed portion side of the telescopic cylinder 43 (see fig. 2). The wire 63 pulled out from the length detector 62 is connected to the support 61 of the cylinder rod side end 45 of the telescopic cylinder 43.

The wire 63 is advanced from the length detector 62 in accordance with the expansion and contraction operation of the expansion cylinder 43. The cylinder length detection mechanism 92 can detect the cylinder length of the telescopic cylinder 43 based on the amount of pulling out the wire 63.

Fig. 8 shows a specific example of the C-pin state detection mechanism 93. Fig. 8 is a view in the direction of C-C of fig. 3. In fig. 8, the C-pin state detection mechanism 93 is constituted by proximity switches 102 and 103.

The proximity switches 102 and 103 are provided in the cylinder portion of the C-pin cylinder 2. An コ -shaped detection piece 104 is provided on the rod portion of the C-pin cylinder 2. In a state where the C-pin 7 of the cylinder/arm coupling mechanism 64 is pulled out from the coupling hole 56b of the top arm 56 (also referred to as a cylinder/arm coupling release state, see fig. 3), one of the proximity switches 102 detects the detection piece 104.

When the C-pin cylinder 2 is released from holding in the extended state and the tip end portion of the C-pin 7 is inserted into the coupling hole 56b by the biasing force of the tension coil spring 8 (see fig. 3), the other proximity switch 103 detects the detection piece 104.

Fig. 4 shows a specific example of the B-pin state detection mechanism 94. In fig. 4, the B-pin state detection mechanism 94 is constituted by proximity switches 114 and 115.

The proximity switches 114 and 115 are provided in the cylinder portion of the B pin cylinder 1. An コ -shaped detection piece 116 is provided on the rod portion of the B-pin cylinder 1.

As shown in fig. 4, in a state where the tip end portion of the B pin 56d of the top arm base end portion 56a is pulled out from the fixing hole 55f of the fifth arm 55 (also referred to as an arm coupling released state), one of the proximity switches 114 detects the detection piece 116.

If the holding of the extended state of the B-pin cylinder 1 is released, the B-pin cylinder 1 is contracted by the urging force of the built-in compression coil spring 5 (see fig. 1). If the tip end portion of the B pin 56d is inserted into the fixing hole 55f by the urging force of the compression coil spring 22, the other proximity switch 115 detects the detection piece 116.

Fig. 5 shows a telescopic cylinder hydraulic pressure supply unit 105 that supplies hydraulic oil to the telescopic cylinder 43, and a hydraulic pressure supply unit 20 that supplies hydraulic oil to the C pin cylinder 2 of the cylinder/arm coupling mechanism 64 and the B pin cylinder 1 of the B pin drive mechanism 73.

The telescopic cylinder hydraulic pressure supply unit 105 supplies the hydraulic oil to the telescopic cylinder 43 based on a control signal from the controller 35. The hydraulic pressure supply unit 20 supplies the hydraulic oil to one of the C-pin cylinder 2 and the B-pin cylinder 1 selected by the controller 35 based on a control signal from the controller 35.

The telescopic cylinder hydraulic pressure supply unit 105 will be described below. The details of the hydraulic pressure supply unit 20 are as already described with reference to fig. 1, and therefore are omitted.

The telescopic cylinder hydraulic pressure supply unit 105 includes a back pressure valve 106, a pilot switching valve 107, an electromagnetic proportional valve 108, an electromagnetic proportional valve 109, and a flow rate control valve 110.

The pump port of the pilot switching valve 107 is connected to a hydraulic pressure source P via a flow rate control valve 110. Further, a tank T is connected to a tank port of the pilot switching valve 107. The hydraulic pressure source P is provided around the base arm base end portion 51 a. The position of the hydraulic pressure source P is not limited to that of the present embodiment. The hydraulic pressure source P corresponds to an example of the first hydraulic pressure source. The hydraulic oil discharged from the hydraulic pressure source P corresponds to an example of the first hydraulic oil.

The electromagnetic proportional valves 108, 109 are proportionally controlled by a control signal from the controller 35. The pilot switching valve 107 is switched by the output pilot pressures of the electromagnetic proportional valves 108 and 109.

The 1 st outlet port of the pilot switching valve 107 and the extension-side oil chamber of the telescopic cylinder 43 are connected through a hydraulic line 111 via a back pressure valve 106. The 2 nd outlet port of the pilot switching valve 107 is connected to the reduction side oil chamber of the telescopic cylinder 43 through a hydraulic line 112.

Hereinafter, the operation of the telescopic device according to the present embodiment will be described with reference to fig. 1 to 8. Specifically, the expansion of the telescopic device from the fully contracted state of the 6-stage telescopic arm 50 (see fig. 2) to the state in which the top arm 56 and the fifth arm 55 of the lift truck 113 are expanded (see fig. 9) will be described as an example. In the following description, the top arm 56 corresponds to an example of the inner arm. The fifth arm 55 corresponds to an example of the outer arm.

At the start of the extension operation, the telescopic arm 50 is in a fully contracted state as shown in fig. 2. At this time, the cylinder/arm coupling mechanism 64 is coupled to the base end portion 56a of the top arm 56. All the adjacent pair of arms are fixed by the arm coupling mechanism 70. The B-pin drive mechanism 73 is coupled to the B-pin 56d of the top arm 56.

First, the operator selects an arm condition on the display screen 84 of the telescopic information display means 83 by operating the forward/return key of the final arm state input means 82. As an example, if the operator selects the arm condition of number 5 (see fig. 6) in which the top arm (6 th stage) is extended by 93% and the fifth arm (5 th stage) is extended by 93%, and operates the set key of the final arm state input mechanism 82, the selected arm condition is output to the controller 35 and stored. Hereinafter, the arm condition selected by the operator is referred to as a selected arm condition.

Next, the operator operates the telescopic operation lever 81 to the extension side and maintains the operation state. Then, the controller 35 automatically controls the telescopic device to extend the telescopic arm 50 until the selected arm condition (in this example, the arm condition of number 5 in fig. 6) is reached. At this time, the controller 35 repeatedly performs a plurality of steps described below as 1 cycle until the selected arm condition is satisfied.

Specifically, in the above-described 1 cycle, the controller 35 sequentially performs an arm coupling release step, an arm extension and contraction step (here, an arm extension step), an arm coupling step, a cylinder/arm coupling release step, an extension and contraction cylinder reduction step, and a cylinder/arm coupling step. Further, if the operator returns the telescopic operation lever 81 to the neutral position during the telescopic operation of the telescopic arm 50, the controller 35 stops the operation of the telescopic device.

(arm connection releasing step)

The arm connection releasing step includes: a step of moving the B pin 4 to release the connection between the pair of adjacent arms (hereinafter referred to as a first step of the arm connection release step), and a step of holding the B pin 4 at the moved position (hereinafter referred to as a second step of the arm connection release step).

First, in the first step of the arm coupling/releasing step, the controller 35 outputs a control signal for instructing to pull out the B pin 56d of the top arm 56 from the fifth arm 55 (to extend the B pin cylinder 1) to the hydraulic pressure supply unit 20 based on the operation of the telescopic operation lever 81 by the operator. Specifically, the controller 35 outputs control signals for turning on the energization to the 1 st electromagnetic switching valve 14, turning off the energization to the 2 nd electromagnetic switching valve 15, and turning on the energization to the 3 rd electromagnetic switching valve 16.

In the first step of the arm connection releasing step, the 1 st electromagnetic changeover valve 14 is in the second state (energized state). In the arm connection releasing step, the 2 nd electromagnetic changeover valve 15 is in the first state (non-energized state). In the arm connection releasing step, the 3 rd electromagnetic changeover valve 16 is in the second state (energized state).

The hydraulic oil of the hydraulic unit 24 (the pressurized hydraulic oil accumulated in the hydraulic accumulator 31) is supplied to the B pin cylinder 1 through the 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, the 3 rd electromagnetic switching valve 16, and the hydraulic line 6. Then, the B pin cylinder 1 is driven to the extension side while compressing the built-in compression coil spring 5, and moves the B pin 4 to the release side.

Referring to fig. 4, the operation of the arm coupling mechanism 70 in the first step of the arm coupling release step will be described. The B-pin cylinder 1 extends, and the B-pin drive feeler lever 74 is moved to the release side. The B pin 56d of the top arm 56 is retracted against the urging force of the compression coil spring 22, and is pulled out from the fixing hole 55 f. The controller 35 recognizes that the fixation of the pair of adjacent arms is released based on a detection signal from the proximity switch 115 of the B-pin state detection mechanism 94.

Next, in the second step of the arm connection releasing step, the controller 35 outputs control signals for turning off the energization to the 1 st electromagnetic switching valve 14, turning on the energization to the 2 nd electromagnetic switching valve 15, and turning on the energization to the 3 rd electromagnetic switching valve 16.

In the second step of the arm connection releasing step, the 1 st electromagnetic changeover valve 14 is in the first state (non-energized state). In the second step of the arm connection releasing step, the 2 nd electromagnetic switching valve 15 is in the second state (energized state). In the second step of the arm connection releasing step, the 3 rd electromagnetic switching valve 16 is in the second state (energized state).

In the second step of the arm connection/disconnection step, the hydraulic oil is held in the hydraulic line 6 between the 2 nd electromagnetic switching valve 15 and the B pin cylinder 1. In this state, the extended state of the B pin cylinder 1 is maintained. That is, the B pin 56d is maintained in a state of being pulled out from the fixing hole 55f of the fifth arm 55.

In this way, the fixed state of the top arm base end portion 56a and the fifth arm 55 is released. After the arm connection/disconnection step is completed, the process proceeds to a subsequent arm extension step.

The hydraulic line 6 from the hydraulic unit 24 to the B-pin cylinder 1 is very short and therefore hardly affected by viscosity changes due to temperature drops. As a result, excellent responsiveness can be obtained in the arm connection/disconnection step.

(arm extension step)

In the arm extending step, the controller 35 outputs a control signal for instructing the extension cylinder 43 to extend to the extension cylinder hydraulic pressure supply unit 105. Specifically, the controller 35 outputs a control signal to the electromagnetic proportional valve 109 to apply a pilot pressure proportional to the operation amount of the telescopic operation lever 81 to the pilot switching valve 107.

The pilot switching valve 107 is connected to a hydraulic pressure source P, and the hydraulic pressure from the hydraulic pressure source P is sent to the extension side oil chamber of the telescopic cylinder 43 through a hydraulic line 111 and a back pressure valve 106. Then, the telescopic cylinder 43 extends. Then, the top arm 56 is extended as the telescopic cylinder 43 is extended.

In the arm extending step, the controller 35 calculates a distance (hereinafter referred to as a first distance) between the B pin 56d of the top arm 56 coupled to the B pin drive mechanism 73 and the fixing hole of the fifth arm 55 based on the detection signal from the cylinder length detection mechanism 92. The fixing hole of the fifth arm 55 is a fixing hole into which the B pin 56d of the top arm 56 coupled to the B pin drive mechanism 73 is inserted in an arm coupling step described later.

In the arm extending step, the first distance calculated by the controller 35 is a distance in the axial direction of the telescopic arm 50. When the first distance is equal to or less than the predetermined distance, the controller 35 outputs a signal (hereinafter, also simply referred to as a deceleration signal) for decelerating the extension speed of the telescopic cylinder 43 (that is, the moving speed of the cylinder tube 44) to the telescopic cylinder hydraulic pressure supply unit 105. The case where the first distance is equal to or less than the predetermined distance may be understood as a case where the B pin 56d reaches the deceleration start point.

Specifically, in the arm extending step, the cylinder length detecting means 92 continuously sends a detection signal indicating the length of the telescopic cylinder 43 to the controller 35. When the B pin 56d reaches the deceleration start point, the controller 35 gradually decreases the value of the output signal to the electromagnetic proportional valve 109. That is, when the B pin 56d reaches the deceleration start point, the controller 35 outputs a control signal (also referred to as a first deceleration control signal) for gradually slowing down the extension speed of the telescopic cylinder 43 to the electromagnetic proportional valve 109.

Then, the pilot pressure applied from the electromagnetic proportional valve 109 to the pilot switching valve 107 is gradually decreased in accordance with the first deceleration control signal. As a result, the spool of the pilot-operated switching valve 107 gradually returns.

If the spool of the pilot switching valve 107 is gradually returned, the opening area of the 1 st outlet port of the pilot switching valve 107 is gradually reduced. As a result, the flow rate of the hydraulic oil discharged from the 1 st outlet port of the pilot switching valve 107 decreases. This reduces the extension speed of the telescopic cylinder 43.

Then, when determining that the B pin 56d of the top arm 56 has reached the position of the fixing hole inserted in the arm coupling step described later, the controller 35 stops the extension operation of the telescopic cylinder 43. After the arm extending step is completed, the process proceeds to the subsequent arm connecting step.

(arm connecting step)

In the arm connecting step, the controller 35 outputs a control signal for instructing the hydraulic pressure supply unit 20 to insert the B pin 56d of the top arm 56 into the fixing hole of the fifth arm 55 (to reduce the B pin cylinder 1).

Specifically, the controller 35 outputs control signals for switching the energization to the 1 st electromagnetic switching valve 14 to off, the energization to the 2 nd electromagnetic switching valve 15 to off, and the energization to the 3 rd electromagnetic switching valve 16 to on.

In the arm connecting step, the 1 st electromagnetic switching valve 14 is in the first state (non-energized state). In the arm connecting step, the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state). In the arm connecting step, the 3 rd electromagnetic switching valve 16 is in the second state (energized state).

Thereby, the hydraulic oil held between the 2 nd electromagnetic switching valve 15 and the B pin cylinder 1 is returned to the hydraulic tank 27 through the 1 st electromagnetic switching valve 14 and the return oil passage 32. The B-pin cylinder 1 is contracted by the biasing force of the built-in compression coil spring 5, and the B-pin 4 is moved to the fixed side by the biasing force of the compression coil spring 22 (see fig. 1).

Referring to fig. 4, the operation of the arm coupling mechanism 70 in the arm coupling step will be described. In the arm connecting step, the B pin drives the rocker 74 to swing as the B pin cylinder 1 is contracted. If the B pin drive lever 74 swings, the B pin 56d moves to the fixed side via the roller 75.

As a result, the B pin 56d of the top arm 56 is inserted into the fixing hole 55f of the fifth arm 55. Thus, the tip arm base end portion 56a is coupled to the fifth arm 55. The controller 35 recognizes that the pair of adjacent arms are connected to each other based on the detection signal from the proximity switch 115.

In this way, the tip arm base end portion 56a is coupled to the fifth arm 55. When the arm connecting step is completed, the process proceeds to a subsequent cylinder/arm connecting/disconnecting step.

In this arm connecting step, too, since the hydraulic line from the B pin cylinder 1 to the hydraulic tank 27 is very short, the delay in operation does not become a problem. As a result, excellent responsiveness can be obtained also in the arm connecting step.

(Cylinder/arm connection releasing step)

Further, if the operation of the telescopic operation lever 81 to the extension side is continued, the cylinder/arm connection releasing step is performed.

In the cylinder/arm coupling release step, the controller 35 outputs a control signal for instructing the release of the coupling state of the C-pin 7 and the top arm 56 to the hydraulic pressure supply unit 20. Specifically, the controller 35 outputs control signals for switching on the power supply to the 1 st electromagnetic switching valve 14, switching off the power supply to the 2 nd electromagnetic switching valve 15, and switching off the power supply to the 3 rd electromagnetic switching valve 16.

In the cylinder/arm connection releasing step, the 1 st electromagnetic changeover valve 14 is in the second state (energized state). In the cylinder/arm connection releasing step, the 2 nd electromagnetic changeover valve 15 is in the first state (non-energized state). In the cylinder/arm connection releasing step, the 3 rd electromagnetic changeover valve 16 is in the first state (non-energized state).

Thereby, the hydraulic oil of the hydraulic unit 24 (the pressurized hydraulic oil accumulated in the hydraulic accumulator 31) is supplied to the C-pin cylinder 2 through the 1 st electromagnetic switching valve 14, the 2 nd electromagnetic switching valve 15, the 3 rd electromagnetic switching valve 16, and the hydraulic line 9. The C-pin cylinder 2 is driven to the extension side while pulling the pull coil spring 8, and moves the C-pin 7 to the release side.

Referring to fig. 3, a cylinder/arm coupling/decoupling step will be described. In the cylinder/arm coupling release step, the C-pin cylinder 2 is extended, and the C-pin 7 is pulled out from the coupling hole 56b of the top arm 56 via the C-pin drive feeler lever 21.

Thereby, the cylinder rod side end portion 45 of the telescopic cylinder 43 (the movable portion 11 of the telescopic cylinder 43) and the boom base end portion 56a are released from being connected. The controller 35 recognizes that the connection state between the cylinder and the arm is released based on a detection signal from the proximity switch 102 (see fig. 8).

In this way, the connection state between the boom base end portion 56a and the movable portion 11(C pin 7) of the telescopic cylinder 43 is released. When the cylinder/arm connection releasing step is completed, the process proceeds to a subsequent telescopic cylinder reducing step.

In this cylinder/arm coupling release step, too, the hydraulic line between the hydraulic unit 24 and the C-pin cylinder 2 is very short, and this delay in operation does not become a problem. As a result, excellent responsiveness can be obtained also in the cylinder/arm coupling/uncoupling step.

(Telescopic cylinder reducing process)

In the telescopic cylinder reducing step, the controller 35 outputs a control signal for instructing the telescopic cylinder 43 to reduce to the telescopic cylinder hydraulic pressure supply unit 105. Specifically, the controller 35 outputs a control signal to the electromagnetic proportional valve 108.

As a result, the pilot switching valve 107 is switched, and the hydraulic pressure source P is connected to the 2 nd outlet port of the pilot switching valve 107. Then, the working oil from the hydraulic source P is supplied to the reduction-side oil chamber of the telescopic cylinder 43 through the hydraulic line 112. Thereby, the telescopic cylinder 43 starts the contraction operation alone.

In the telescopic cylinder reducing step, the controller 35 calculates a distance (hereinafter referred to as a second distance) between the C-pin 7 and the coupling hole of the fifth arm 55 based on a detection signal from the cylinder length detecting means 92. The coupling hole of the fifth arm 55 is a coupling hole into which the C-pin 7 is inserted in a cylinder/arm coupling step described later.

In the telescopic cylinder reducing process, the second distance calculated by the controller 35 is a distance in the axial direction of the telescopic arm 50. When the second distance is equal to or less than the predetermined distance, the controller 35 outputs a signal (hereinafter, also simply referred to as a deceleration signal) for decelerating the retraction speed of the telescopic cylinder 43 (that is, the moving speed of the cylinder tube 44) to the telescopic cylinder hydraulic pressure supply unit 105. The second distance is equal to or less than the predetermined distance, and it can be understood that the C-pin 7 reaches the deceleration start point.

Specifically, in the telescopic cylinder reducing step, the cylinder length detecting means 92 continuously sends a detection signal indicating the length of the telescopic cylinder 43 to the controller 35. When the C-pin 7 reaches the deceleration start point, the controller 35 gradually decreases the value of the output signal to the electromagnetic proportional valve 108. That is, when the C-pin 7 reaches the deceleration start point, the controller 35 outputs a control signal (also referred to as a second deceleration signal) for gradually slowing down the contraction speed of the telescopic cylinder 43 to the electromagnetic proportional valve 108.

Then, the pilot pressure applied from the electromagnetic proportional valve 108 to the pilot switching valve 107 is gradually decreased in accordance with the second deceleration control signal. As a result, the spool of the pilot-operated switching valve 107 gradually returns.

If the spool of the pilot switching valve 107 is gradually returned, the opening area of the 2 nd outlet port of the pilot switching valve 107 is gradually reduced. As a result, the flow rate of the hydraulic oil discharged from the 2 nd output port of the pilot switching valve 107 decreases. This reduces the contraction speed of the telescopic cylinder 43.

Then, when determining that the C pin 7 has reached the position of the coupling hole of the fifth arm 55 inserted in the cylinder/arm coupling step described later, the controller 35 stops the contraction operation of the telescopic cylinder 43. When the telescopic cylinder reducing process is finished, the process shifts to a subsequent cylinder/arm connecting process.

In the telescopic cylinder reducing step, the controller 35 determines whether or not the C-pin 7 has reached the target position based on the detection signal from the cylinder length detecting means 92 and the detection signal from the arm base end position detecting means 91. That is, if the proximity switch 96 (see fig. 7) detects the detection piece 55g provided at the fifth arm base end portion 55a, the controller 35 determines that the C-pin 7 has reached the target position.

(oil cylinder/arm connecting step)

In the cylinder/arm coupling step, the controller 35 outputs a control signal for instructing the coupling of the C-pin 7 and the fifth arm 55 to the hydraulic pressure supply unit 20. Specifically, the controller 35 outputs control signals for switching the energization to the 1 st electromagnetic switching valve 14 to off, the energization to the 2 nd electromagnetic switching valve 15 to off, and the energization to the 3 rd electromagnetic switching valve 16 to off.

In the cylinder/arm connecting step, the 1 st electromagnetic switching valve 14 is in the first state (non-energized state). In the cylinder/arm connecting step, the 2 nd electromagnetic switching valve 15 is in the first state (non-energized state). In the cylinder/arm connecting step, the 3 rd electromagnetic switching valve 16 is in the first state (non-energized state).

Accordingly, the hydraulic oil supplied to the oil chamber of the C-pin cylinder 2 is returned to the hydraulic tank 27 through the hydraulic line 9, the 3 rd electromagnetic switching valve 16, the 2 nd electromagnetic switching valve 15, the 1 st electromagnetic switching valve 14, and the return line 32. The C-pin cylinder 2 is driven to the reduction side by the biasing force of the pull coil spring 8, and moves the C-pin 7 to the connection side.

The C-pin cylinder 2 is contracted, the C-pin drive feeler lever 21 is moved, and the C-pin 7 is inserted into the coupling hole 55b of the fifth arm base end portion 55 a. The C-pin 7 is inserted into the coupling hole 55b, and the cylinder rod side end portion 45 of the telescopic cylinder 43 (the movable portion 11 of the telescopic cylinder 43) and the fifth arm base end portion 55a are coupled.

The controller 35 recognizes that the telescopic cylinder 43 and the fifth arm 55 are coupled based on a detection signal from the proximity switch 103 (see fig. 8).

In this cylinder/arm connecting step, too, since the hydraulic line from the C-pin cylinder 2 to the hydraulic oil tank 24 is extremely short, delay in operation thereof does not become a problem. Thereafter, if the fifth arm 55 is extended to the final arm state shown in fig. 9 by repeating the above-described steps, the controller of the telescopic device ends the operation.

As described above, the telescopic device of the present embodiment includes: a single telescopic cylinder 43 which is built in the telescopic arm 50 and one end of which is pivotally supported at a base end part 51a of the base arm 51, wherein a plurality of arms 51 to 56 including the base arm 51, the intermediate arms 52 to 55 and the top arm 56 are respectively inserted into the telescopic arm 50 in a freely telescopic manner; an arm connecting mechanism 70 having B-pins 52d to 56d (fixed pins) and a B-pin cylinder 1 (1 st hydraulic cylinder) for inserting and removing the B-pins 52d to 56d, and fixing 2 adjacent arms of the plurality of arms 51 to 56 by the B-pins 52d to 56 d; a cylinder/arm connecting mechanism 64 having a C pin 7 (connecting pin) and a C pin cylinder 2 (2 nd hydraulic cylinder) for inserting and removing the C pin 7, and connecting a specific arm to be extended or contracted among the plurality of arms 52 to 56 to the telescopic cylinder 43 via the C pin 7; and a hydraulic pressure supply unit 20 (hydraulic pressure supply unit) that supplies hydraulic pressure to the B pin cylinder 1 and the C pin cylinder 2. The telescopic device extends and contracts the telescopic cylinder 43 so that the plurality of arms 52 to 56 are extended and contracted by 1 segment at a time by extending and contracting the telescopic cylinder 43 in a state where the specific arm is connected to the telescopic cylinder 43 and the fixed state of the adjacent 2 arms including the specific arm is released.

The hydraulic pressure supply unit 20 further includes: the hydraulic unit 24, the solenoid directional control valves 14 to 16 (directional control valves) for switching the delivery destination of the hydraulic oil from the hydraulic unit 24, the hydraulic line 6 delivered from the solenoid directional control valves 14 to 16 to the B pin cylinder 1, and the hydraulic line 9 delivered from the solenoid directional control valves 14 to 16 to the C pin cylinder 2.

The hydraulic pressure supply unit 20 is disposed in the movable unit 11 of the telescopic cylinder 43.

Since all of the hydraulic unit 24 and the electromagnetic switching valves 14 to 16 constituting the hydraulic pressure supply unit 20 are disposed on the movable portion 11 of the telescopic cylinder 43, the hydraulic line connecting the hydraulic unit 24 to the B pin cylinder 1 and the C pin cylinder 2 is extremely short. Therefore, excellent responsiveness can be obtained in both the B pin cylinder 1 and the C pin cylinder 2 regardless of the ambient temperature. Therefore, the operability of the expansion device is ensured even at low temperatures.

In addition, a large and heavy hose reel is not required, and therefore the frame-mounting performance of the lift truck is improved. And a complicated and difficult-to-manufacture telescopic cylinder such as a telescopic cylinder with a built-in oil delivery pipe is not required.

Description of the reference numerals

1B pin oil cylinder

100. 101 support

102. 103 approach switch

104 test piece

105 telescopic oil cylinder hydraulic pressure supply part

106 back pressure valve

107 pilot operated switching valve

108. 109 electromagnetic proportional valve

110 flow control valve

11 moving part

113 crane

114. 115 proximity switch

116 detection piece

14 st electromagnetic switching valve

15 nd 2 nd electromagnetic switching valve

16 rd 3 electromagnetic switching valve

2C pin oil cylinder

20 hydraulic pressure supply part

22 compression coil spring

24 hydraulic unit

25 electric motor

26 hydraulic pump

27 oil tank

28 check valve

29 high pressure filter

30 discharge line

31 hydraulic pressure accumulator

32 return line

33 relief valve

34 hydraulic pressure sensor

35 controller

37 Cable reel

38 power line

39. 40, 41, 42 control signal line

4B pin

43 telescopic oil cylinder

44 oil cylinder barrel

45-cylinder barrel rod side end part

5 compression coil spring

50 telescopic arm

51 base arm

Base end of 51a base arm

52 second arm (middle arm)

52a second arm base end part

52 b-56 b connecting holes

52d B pin

52 g-56 g detection piece

53 third arm (middle arm)

53a third arm base end part

53d B pin

54 fourth arm (middle arm)

54a fourth arm base end part

54d B pin

55 fifth arm (middle arm)

55a fifth arm base end part

55d B pin

55f fixing hole

56 top arm

56a apical arm base end

56b connecting hole

56d B pin

6 hydraulic pipeline

60 Cable

62 length detector

63 cord

64 cylinder/arm linkage

65 trunnion component

66C pin receiving hole

7C pin

70 arm connecting mechanism

72 connecting member

73B pin driving mechanism

75 roller

8-pulling coil spring

80 telescopic operating mechanism

81 telescopic operation touch rod

82 final arm state input mechanism

83 telescopic information display mechanism

84 display screen

85 extended length

Elongation ratio of 86

87 round mark

88 frame cursor

9 Hydraulic line

90 telescopic state detection mechanism

91-arm base end position detection mechanism

92 oil cylinder length detection mechanism

93C round pin state detection mechanism

94B pin state detection mechanism

95 ~ 99 proximity switch