阅读说明：本技术 油压系统 (Oil pressure system ) 是由 近藤哲弘 于 2018-05-18 设计创作，主要内容包括：油压系统具备：操作装置；随着从操作装置输出的操作信号变大而增大向油压执行器供给工作油的通路的开口面积的控制阀；可变容量型的泵；随着控制压升高而增大所述泵的倾转角的调节器；随着从操作装置输出的操作信号越大而输出越高的二次压的第一电磁比例阀及第二电磁比例阀；随着从第一电磁比例阀输出的二次压越高,开口面积越从全开状态向全闭状态减少的卸载阀；以及选择从第一电磁比例阀输出的二次压与从第二电磁比例阀输出的二次压中的高的一方来作为控制压导向调节器的高压选择阀。(The hydraulic system includes an operation device, a control valve that increases an opening area of a passage through which hydraulic oil is supplied to a hydraulic actuator as an operation signal output from the operation device increases, a variable displacement pump, a regulator that increases a tilt angle of the pump as a control pressure increases, an -th and second electromagnetic proportional valves that output higher secondary pressures as an operation signal output from the operation device increases, an unloader valve that decreases an opening area from a fully open state to a fully closed state as a secondary pressure output from a -th electromagnetic proportional valve increases, and a high-pressure selector valve that selects, as a control pressure pilot regulator, a higher side of the secondary pressure output from a -th electromagnetic proportional valve and the secondary pressure output from the second electromagnetic proportional valve.)

An type hydraulic system, comprising:

an operation device that outputs an operation signal corresponding to an operation amount for the operation unit;

a control valve that increases an opening area of a passage through which hydraulic oil is supplied to the hydraulic actuator as an operation signal output from the operation device increases;

a variable displacement pump connected to the control valve through a supply line;

a regulator that increases a tilt angle of the pump as a control pressure increases;

an th electromagnetic proportional valve that outputs a higher secondary pressure as the operation signal output from the operation device is larger;

an unloading valve provided on an unloading line branched from the supply line and having an opening area that decreases from a fully open state to a fully closed state as the secondary pressure output from the -th electromagnetic proportional valve increases;

a second electromagnetic proportional valve which outputs a higher secondary pressure as the operation signal output from the operation device increases, and in which the secondary pressure of the second electromagnetic proportional valve is set higher than the secondary pressure of the -th electromagnetic proportional valve in response to the operation signal of , and

a high pressure select valve that selects a higher side of the secondary pressure output from the th electromagnetic proportional valve and the secondary pressure output from the second electromagnetic proportional valve as the control pressure and leads to the regulator.

2. The oil hydraulic system of claim 1,

the unloading valve is provided with a pilot port connected with the electromagnetic proportional valve, and is formed in a structure that when the pilot pressure guided to the pilot port rises from a set value to a second set value, the opening area decreases from a specified value to zero by a gradient of or a curve which is convex upwards along a straight line relative to the gradient;

the regulator is configured to maintain a discharge flow rate of the pump at a minimum discharge flow rate while the control pressure is increased at least from zero to the th set value.

Technical Field

The present invention relates to an electric Positive Control (Positive Control) hydraulic system.

Background

Conventionally, an electric positive control type hydraulic system is used in construction machines, industrial machines, and the like. For example, patent document 1 discloses a hydraulic system 100 for a construction machine as shown in fig. 4.

In the hydraulic system 100, the hydraulic oil is supplied from the variable displacement pump 110 to each hydraulic actuator 130 via the control valve 120. The control valve 120 increases the opening area of a passage through which the hydraulic oil is supplied to the hydraulic actuator 130 as the amount of operation of the corresponding operation unit (operation lever in fig. 4) of the operation device 140 increases.

The tilt angle of the pump 110 is adjusted by the adjuster 111. The regulator 111 is connected to an electromagnetic proportional valve 112. The electromagnetic proportional valve 112 outputs a higher secondary pressure as the operation amount of the operation portion of the operation device 140 is larger. Accordingly, the discharge flow rate of the pump 110 increases as the operation amount of the operation unit of the operation device 140 increases.

The hydraulic system 100 is provided with an unloading valve 150 for discharging the hydraulic oil discharged from the pump 110 to the reservoir during standby (in a state where all the operation devices 140 are not operated). The unloading valve 150 has a pilot port, and is configured such that the opening area decreases from the fully open state to the fully closed state as the pilot pressure directed to the pilot port increases. The pilot port of the unloader valve 150 is connected to a solenoid proportional valve 160. The electromagnetic proportional valve 160 outputs a higher secondary pressure as the operation amount of the operation portion of the operation device 140 is larger.

Disclosure of Invention

The problems to be solved by the invention are as follows:

however, in the hydraulic system 100 shown in fig. 4, when the electromagnetic proportional valve 112 for the regulator 111 fails, the secondary pressure of the electromagnetic proportional valve 112 may become zero. In this case, even when the operation portion of the operation device 140 is operated, the discharge flow rate of the pump 110 is maintained at the minimum discharge flow rate, and the hydraulic actuator 130 cannot be operated at a sufficient speed.

Therefore, an object of the present invention is to provide types of hydraulic systems capable of operating a hydraulic actuator at a sufficient speed even when a regulator proportional solenoid valve fails and its secondary pressure becomes zero.

Means for solving the problems:

in order to solve the above-described problems, a hydraulic system according to the present invention includes an operation device that outputs an operation signal according to an operation amount to an operation portion, a control valve that increases an opening area of a passage that supplies hydraulic oil to a hydraulic actuator as an operation signal output from the operation device increases, a variable displacement pump connected to the control valve through a supply line, a regulator that increases a tilt angle of the pump as a control pressure increases, a electromagnetic proportional valve that outputs a higher secondary pressure as an operation signal output from the operation device increases, an unloading valve that is provided on an unloading line that branches from the supply line and that outputs a higher secondary pressure as a secondary pressure output from the second electromagnetic proportional valve increases, a second electromagnetic proportional valve that is provided on the unloading line that branches from the supply line and that outputs a higher secondary pressure as an operation signal output from the first electromagnetic proportional valve increases, the second electromagnetic proportional valve being set to be higher than the secondary pressure of the second electromagnetic proportional valve for the same operation signal, and the second electromagnetic proportional valve that outputs the higher secondary pressure as the secondary pressure, and the second electromagnetic proportional valve 53982 that is selected and that is output from the second electromagnetic proportional valve, and the second electromagnetic proportional valve that outputs the second electromagnetic proportional valve that selects the high pressure as the high pressure that is output from the .

According to the above configuration, when the second electromagnetic proportional valve is normal, the secondary pressure of the second electromagnetic proportional valve is introduced into the regulator, and the tilt angle (discharge flow rate) of the pump can be controlled by the second electromagnetic proportional valve, and further , when the second electromagnetic proportional valve fails and the secondary pressure of the second electromagnetic proportional valve becomes zero, the secondary pressure of the th electromagnetic proportional valve is introduced into the regulator, and thus the tilt angle of the pump increases as the operation signal increases, and as a result, the hydraulic actuator can be operated at a sufficient speed, that is, when the second electromagnetic proportional valve for the regulator fails, the unloading valve that is originally present in the hydraulic system can be used as a substitute for the th electromagnetic proportional valve.

The unloader valve may have a pilot port connected to the th electromagnetic proportional valve, and may be configured such that when a pilot pressure to be led to the pilot port rises from a th set value to a second set value, an opening area decreases from a predetermined value to zero at an inclination of or along a curve that is convex upward along a straight line with respect to the inclination, and the regulator may be configured such that the discharge flow rate of the pump is maintained at a minimum discharge flow rate during a period in which the control pressure rises from at least zero to the th set value, and such that when the second electromagnetic proportional valve fails, the discharge flow rate of the pump increases after the opening area of the unloader valve starts to decrease at an inclination of , and therefore, while the opening area of the unloader valve is sufficiently secured in a standby state, a problem may be avoided that when the discharge flow rate of the pump increases from a minimum flow rate, the opening area of the unloader valve becomes excessively large, and the rise of the discharge pressure is delayed.

The invention has the following effects:

according to the present invention, even when the regulator electromagnetic proportional valve fails and the secondary pressure thereof becomes zero, the hydraulic actuator can be operated at a sufficient speed.

Drawings

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention;

fig. 2 is a graph showing a relationship between an operation amount of an operation portion of the operation device and secondary pressures of an th and second electromagnetic proportional valves;

fig. 3A is a graph showing a relationship between a control pressure to the regulator and a discharge flow rate of the pump, and fig. 3B is a graph showing a relationship between a pilot pressure of the unloader valve and an opening area;

fig. 4 is a schematic configuration diagram of a hydraulic system of a conventional construction machine.

Detailed Description

Fig. 1 shows a hydraulic system 1 according to an embodiment of the present invention, and the hydraulic system 1 is mounted on a construction machine such as a hydraulic excavator or a hydraulic crane, a civil engineering machine, an agricultural machine, or an industrial machine.

Specifically, the hydraulic system 1 includes the hydraulic actuator 24 and the main pump 21 that supplies the hydraulic fluid to the hydraulic actuator 24 via the control valve 3, and in the illustrated example, combinations (sets) of the hydraulic actuator 24 and the control valve 3 are provided, but a plurality of combinations of the hydraulic actuator 24 and the control valve 3 may be provided.

The main pump 21 is a variable displacement pump whose tilt angle can be changed. The main pump 21 may be a swash plate pump or a swash plate pump. The tilting angle of the main pump 21 is adjusted by the regulator 22.

The main pump 21 is connected to the control valve 3 via the supply line 11. The discharge pressure of the main pump 21 is kept at or below the relief pressure by the relief valve 12.

In the present embodiment, the hydraulic actuator 24 is a double acting cylinder, and the control valve 3 is connected to the supply and discharge line 31 and the hydraulic actuator 24 through , however, the hydraulic actuator 24 may be a single acting cylinder, and the control valve 3 may be connected to the hydraulic actuator 24 through supply and discharge lines 31, or the hydraulic actuator 24 may be a hydraulic motor.

The control valve 3 is switched from the neutral position to the th position (a position where the hydraulic actuator 24 is operated in the direction) or the second position (a position where the hydraulic actuator 24 is operated in the reverse direction) by the operation device 4 being operated, in the present embodiment, the control valve 3 is of a hydraulic pilot type and has pairs of pilot ports, but the control valve 3 may be of an electromagnetic pilot type.

The operation device 4 includes an operation unit 41 and outputs an operation signal according to an operation amount to the operation unit 41. That is, the operation signal output from the operation device 4 becomes larger as the operation amount becomes larger. The operation unit 41 is, for example, an operation lever, but may be a foot pedal or the like.

In the present embodiment, the operation device 4 is a pilot operation valve that outputs a pilot pressure as an operation signal, and therefore, the operation device 4 is connected to the pilot port of the control valve 3 through , and the control valve 3 increases the opening area of a passage through which hydraulic oil is supplied to the hydraulic actuator 24 as the pilot pressure (operation signal) output from the operation device 4 increases.

The unloading line 13 branches off from the supply line 11 described above. The unloading line 13 is connected to the tank. The unloading line 13 is provided with an unloading valve 5.

The unloader valve 5 is of a pilot type and has a pilot port 51. The unloading valve 5 is configured such that the opening area decreases from the fully open state to the fully closed state as the pilot pressure to the pilot port 51 increases. That is, the opening area of the unloader valve 5 is maximized in the neutral state.

The pilot port 51 is connected to a secondary pressure port of the -th electromagnetic proportional valve 6 via a secondary pressure line 62, and the -th secondary pressure port of the -th electromagnetic proportional valve 6 is connected to the sub-pump 23 via a -th secondary pressure line 61, and the discharge pressure of the sub-pump 23 is maintained at the set pressure by the relief valve 15.

The th electromagnetic proportional valve 6 is of a proportional type that outputs a higher secondary pressure as the command current increases, the th electromagnetic proportional valve 6 is controlled by the control device 9, for example, the control device 9 has a memory such as a ROM or a RAM and a CPU, and a program stored in the ROM is executed by the CPU.

The control device 9 is electrically connected to the pressure sensors 91 provided in the -pair pilot lines 42, respectively, and only a signal line is drawn in fig. 1 to simplify the drawing.

The pressure sensor 91 detects the pilot pressure output from the operation device 4, and the control device 9 increases the command current to be supplied to the -th electromagnetic proportional valve 6 as the pilot pressure output from the operation device 4 increases, that is, the -th electromagnetic proportional valve 6 outputs a higher secondary pressure as the pilot pressure (operation signal) output from the operation device 4 increases, whereby the opening area of the unload valve 5 decreases as the operation amount to the operation unit 41 of the operation device 4 increases.

In the present embodiment, the unloader valve 5 is configured such that the opening area is kept large until the pilot pressure to be led to the pilot port 51 becomes the -th set value α 1 as shown in fig. 3B, and when the pilot pressure rises from the -th set value α 1 to the second set value α 2, the opening area decreases from a predetermined value to zero with a gradient of , but the opening area of the unloader valve 5 does not necessarily decrease linearly when the pilot pressure is between the -th set value α 1 and the second set value α 2, and may decrease along a curve that protrudes upward along the line L with respect to the gradient of as shown by the two-dot chain line in fig. 3B.

More specifically, as shown in fig. 3A, the regulator 22 is configured to maintain the discharge flow rate of the main pump 21 at the minimum discharge flow rate when the control pressure increases from zero to the th set value β 1, and to increase the discharge flow rate of the main pump 21 from the minimum discharge flow rate to the maximum discharge flow rate when the control pressure increases from the th set value β 1 to the second set value β 2, in the present embodiment, the th set value β 1 is set to be larger than the th set value β 01 associated with the unloader valve 5, that is, the discharge flow rate of the main pump 21 is maintained at the minimum discharge flow rate while the control pressure increases from at least zero to the th set value α 1.

Returning to FIG. 1, the regulator 22 is connected to the secondary pressure port of the second solenoid proportional valve 7 via the high pressure selector valve 8 the secondary pressure port of the second solenoid proportional valve 7 is connected to the secondary pump 23 by the secondary pressure line 71.

More specifically, the high-pressure selector valve 8 has two input ports and output ports, and the regulator 22 is connected to the output port of the high-pressure selector valve 8 through an output line 83, and input ports of the high-pressure selector valve 8 are connected to the secondary pressure port of the second electromagnetic proportional valve 7 through an th input line 81. furthermore, the other input ports of the high-pressure selector valve 8 are connected to a secondary pressure line 62 extending from the secondary pressure port of the th electromagnetic proportional valve 6 through a second input line 82. that is, the high-pressure selector valve 8 selects the higher side of the secondary pressure output from the th electromagnetic proportional valve 6 and the secondary pressure output from the second electromagnetic proportional valve 7 as the above-mentioned control pressure and leads it to the regulator 22.

The second electromagnetic proportional valve 7 is a proportional type that outputs a higher secondary pressure as the command current is larger. The second electromagnetic proportional valve 7 is controlled by a control device 9.

Similarly to the -th electromagnetic proportional valve 6, the control device 9 increases the command current to be sent to the second electromagnetic proportional valve 7 as the pilot pressure output from the operation device 4 increases, that is, the second electromagnetic proportional valve 7 outputs a higher secondary pressure as the pilot pressure output from the operation device 4 increases, and thus the discharge flow rate of the main pump 21 increases as the operation amount of the operation portion 41 of the operation device 4 increases.

As described above, in the hydraulic system 1 according to the present embodiment, when the second electromagnetic proportional valve 7 is normal, the secondary pressure of the second electromagnetic proportional valve 7 is introduced into the regulator 22 by the operation of the high-pressure selector valve 8, and the tilt angle (discharge flow rate) of the main pump 21 can be controlled by the second electromagnetic proportional valve 7, and in addition, , when the second electromagnetic proportional valve 7 fails and the secondary pressure of the second electromagnetic proportional valve 7 becomes zero, the secondary pressure of the electromagnetic proportional valve 6 is introduced into the regulator 22, and the tilt angle of the main pump 21 increases as the operation signal increases, and as a result, the hydraulic actuator 24 can be operated at a sufficient speed, that is, when the regulator 22 fails to operate the second electromagnetic proportional valve 7, the unload valve 5 that is originally present in the hydraulic system 1 can be used in place of the second electromagnetic proportional valve 7 using the electromagnetic proportional valve 6.

In the present embodiment, since the discharge flow rate of the main pump 21 increases after the opening area of the unloader valve 5 starts to decrease at an inclination of when the second electromagnetic proportional valve 7 fails, it is possible to avoid a problem that the increase in the discharge pressure is delayed by the excessively large opening area of the unloader valve 5 when the discharge flow rate of the main pump 21 starts to increase from the lowest flow rate, and this effect is also obtained when the opening area of the unloader valve 5 decreases along the curve indicated by the two-dot chain line in fig. 3B in fig. 3, while the opening area of the unloader valve 5 is sufficiently ensured in the standby state.

The present invention is not limited to the above embodiment, and various modifications may be made without departing from the spirit of the present invention. For example, the hydraulic system is a combination of a main circuit including the main pump 21, the control valve 3, the hydraulic actuator 24, and the unload valve 5, and a signal pressure circuit including the electromagnetic proportional valves 6 and 7 and the high pressure selector valve 8.

Description of the symbols:

1 an oil pressure system;

11 a supply line;

21 a main pump;

22 a regulator;

24 oil pressure actuators;

3a control valve;

4 operating the device;

41 an operation part;

5 unloading the valve;

51 a pilot port;

a 6-solenoid proportional valve ( th solenoid proportional valve);

7 solenoid command valve (second solenoid proportional valve);

8 high pressure selector valve.