阅读说明：本技术 电动驱动式流量控制阀 (Electrically driven flow control valve ) 是由 森田启 菅野直纪 前川智史 伊贺上贵幸 于 2019-07-09 设计创作，主要内容包括：提供一种在抑制在连接于电动马达的副阀体作用流体的较高的压力的同时、能够对在两个出入口间流动的流体的流量进行控制的电动驱动式流量控制阀。流量控制阀(1)具备壳体(2)、升降驱动装置(3)、供给切换阀(4)、主阀体(5)和闭阀弹簧(6)。如果借助升降驱动装置的电动马达(31)而副阀体(33)向上方移动,则背压室(20)的油经由副阀体连通口(33T)及副阀体油路(33S)被从排出油路(27)排出。此外,第1油室的油一边在第1节流孔被流量调整一边向背压室流入。相对于主阀体的背压室、第1油室及第2油室的压力、闭阀弹簧的作用力的平衡变化,主阀体开阀。另一方面,在主阀体的闭阀时,阻止背压室的压力对副阀体的下端面直接赋予。(Provided is an electrically driven flow control valve capable of controlling the flow rate of a fluid flowing between two ports while suppressing a high pressure of the fluid acting on a sub-valve body connected to an electric motor. A flow control valve (1) is provided with a housing (2), a lift drive device (3), a supply switching valve (4), a main valve body (5), and a valve closing spring (6). When the sub-valve body (33) is moved upward by an electric motor (31) of the lifting drive device, oil in the back-pressure chamber (20) is discharged from the discharge oil passage (27) through a sub-valve body communication port (33T) and a sub-valve body oil passage (33S). The oil in the 1 st oil chamber flows into the back pressure chamber while being flow-regulated at the 1 st orifice. The main valve body is opened when the balance between the pressures of the back pressure chamber, the 1 st oil chamber and the 2 nd oil chamber of the main valve body and the acting force of the closing spring changes. On the other hand, when the main valve body is closed, the pressure of the back pressure chamber is prevented from being directly applied to the lower end surface of the sub valve body.)

1. An electrically driven flow control valve is characterized in that,

the disclosed device is provided with:

a housing having a1 st fluid chamber, a2 nd fluid chamber, a fluid chamber communication port for communicating the 1 st fluid chamber and the 2 nd fluid chamber, and a cylinder portion, wherein the housing is formed with a1 st inlet/outlet through which a fluid can be introduced and discharged between the outside of the housing and the 1 st fluid chamber, and a2 nd inlet/outlet through which a fluid can be introduced and discharged between the outside of the housing and the 2 nd fluid chamber;

an electric motor;

a main valve body having a main valve body distal end portion capable of closing the fluid chamber communication port, the main valve body being accommodated in the cylinder portion so as to be movable along a predetermined axial direction between a main valve body open position and a main valve body closed position, and a back pressure chamber capable of allowing a fluid to enter and exit from the cylinder portion, the main valve body being configured such that, if the main valve body is disposed at the main valve body open position, the fluid chamber communication port is opened by the main valve body distal end portion to allow a fluid to flow between the 1 st fluid chamber and the 2 nd fluid chamber, and, if the main valve body is disposed at the main valve body closed position, the fluid chamber communication port is closed by the main valve body distal end portion to block a fluid flow between the 1 st fluid chamber and the 2 nd fluid chamber;

a biasing mechanism for biasing the main valve body toward the main valve body closing position;

a1 st communication passage capable of communicating the 1 st fluid chamber and the back pressure chamber with each other;

a2 nd communication passage capable of communicating the 2 nd fluid chamber and the back pressure chamber with each other;

a switching mechanism capable of changing a state between a1 st communication state and a2 nd communication state, the 1 st communication state being a state in which the flow of the fluid in the 1 st communication passage is enabled and the flow of the fluid in the 2 nd communication passage is blocked when the pressure of the fluid in the 1 st fluid chamber is higher than the pressure of the fluid in the 2 nd fluid chamber, the 2 nd communication state being a state in which the flow of the fluid in the 2 nd communication passage is enabled and the flow of the fluid in the 1 st communication passage is blocked when the pressure of the fluid in the 1 st fluid chamber is lower than the pressure of the fluid in the 2 nd fluid chamber;

a1 st flow rate adjusting mechanism disposed in the 1 st communication passage and configured to adjust a flow rate of the fluid such that the flow rate of the fluid flowing from the 1 st fluid chamber toward the back pressure chamber is decreased;

a2 nd flow rate adjusting mechanism which is arranged in the 2 nd communication passage and adjusts the flow rate of the fluid so as to reduce the flow rate of the fluid flowing from the 2 nd fluid chamber to the back pressure chamber; and

a sub-valve body accommodated in the back pressure chamber, the sub-valve body having a sub-valve body flow passage communicating with the outside of the housing and a sub-valve body communication port communicating the back pressure chamber with the sub-valve body flow passage, the sub-valve body being movable relative to the main valve body in the axial direction between a sub-valve body open position and a sub-valve body closed position by a driving force generated by the electric motor, opening the sub valve body communication port to allow the fluid in the back pressure chamber to be discharged to the outside of the housing through the sub valve body flow path if the sub valve body is disposed at the sub valve body opening position, when the sub valve body is disposed at the sub valve body closing position, the sub valve body communication port is closed to block the flow of the fluid between the back pressure chamber and the sub valve body flow passage, and the main valve body is allowed to be arranged at the main valve body closing position by receiving the biasing force of the biasing mechanism.

2. An electrically driven flow control valve according to claim 1,

the aforementioned fluid chamber communication port has a circular shape when viewed in the aforementioned axial direction;

the main valve body has a conical tip end portion capable of closing the fluid chamber communication port along the axial direction.

3. An electrically driven flow control valve according to claim 1 or 2,

the main valve body has an inner space which communicates with the back pressure chamber on the opposite side to the front end of the main valve body and is formed in a cylindrical shape along the axial direction and into which the sub valve body can enter, and a front end inner wall portion which defines the inner space on the front end side of the main valve body;

the sub valve body has a cylindrical portion disposed at least at an end portion on the front end inner wall portion side, and the sub valve body communication port is opened in the cylindrical portion;

the front end inner wall portion has a recessed portion that allows the cylindrical portion of the sub-valve body to enter and is in close contact with the cylindrical portion over the entire circumferential direction.

4. An electrically driven flow control valve according to claim 3,

the sub-valve body communication port is opened in an end surface of the cylindrical portion of the sub-valve body that intersects the axial direction.

5. An electrically driven flow control valve according to claim 4,

the recessed portion of the front end inner wall portion is formed in a conical shape, and if the sub-valve body is disposed at the sub-valve body closing position, the inclined surface of the recessed portion comes into close contact with the circumferential edge of the end surface of the cylindrical portion over the entire circumferential direction.

6. An electrically driven flow control valve according to claim 3,

the sub-valve body communication port is opened in a side surface of the cylindrical portion of the sub-valve body extending in the axial direction;

the concave portion is formed in a cylindrical shape so that the cylindrical portion can enter;

the sub-valve body communication port is disposed at the following position in the cylindrical portion: and a position where the sub valve body communication port is closed if the cylindrical portion enters the recessed portion in response to the movement of the sub valve body, and the sub valve body communication port is communicated with the back pressure chamber if the cylindrical portion is separated from the recessed portion in response to the movement of the sub valve body.

7. An electrically driven flow control valve according to any one of claims 1 to 6,

the 1 st flow rate adjusting means and the 2 nd flow rate adjusting means are orifices disposed in the 1 st communication passage and the 2 nd communication passage, respectively.

8. An electrically driven flow control valve according to any one of claims 1 to 7,

the 1 st flow rate adjustment mechanism and the 2 nd flow rate adjustment mechanism are disposed between the 1 st fluid chamber and the switching mechanism and between the 2 nd fluid chamber and the switching mechanism, respectively.

Technical Field

The present invention relates to an electrically driven flow rate control valve capable of controlling the flow rate of a fluid flowing between two ports.

Background

Conventionally, as a device for controlling a flow rate of a working fluid such as working oil or refrigerant in a flow path of the working fluid, an electrically driven flow rate control valve is known. An electrically driven flow rate control valve includes a housing, a main valve body movable in the housing, a drive source for generating a drive force for moving the main valve body, and a sub-valve body for receiving the drive force of the drive source and transmitting a moving force to the main valve body. The housing is formed with a1 st port and a2 nd port, which are communicated by a communication flow path. The main valve body is movable between a blocking position for blocking the communication flow path and an opening position for opening the communication flow path.

Patent document 1 discloses an electrically operated valve as the electrically driven flow rate control valve described above. The motor-operated valve is provided with a valve body, a lifting drive mechanism, and a valve closing spring. The valve body has a valve chamber, a transverse 1 st inlet and outlet opening in the valve chamber, a longitudinal valve port with a valve seat in the valve chamber, and a2 nd inlet and outlet opening connected to the valve port. The valve body is disposed in the valve chamber so as to be movable up and down for opening and closing the valve port. The lift driving mechanism has an electric motor for lifting the valve body. The valve closing spring biases the valve body in the valve opening direction. The diameter of the valve port is set to be substantially the same as the chamber diameter of a back pressure chamber defined above the valve body, and a pressure equalizing passage having an open lower end surface is provided in the valve body so that the valve port and the back pressure chamber communicate with each other. The dimensions of each portion are set so that the value obtained by dividing the area of the lower end opening of the pressure equalizing passage by the area of the valve port is 0.5 or more and less than 1.0.

Further, patent document 2 discloses a pilot operated valve. The valve has a main body, a main poppet, a pilot piston, a1 st disc spring, a pilot valve element, and an actuator. The main body has a1 st port, a2 nd port, and a valve seat disposed between the 1 st port and the 2 nd port. The main poppet selectively engages the valve seat to form a control chamber. The pressure in the control chamber controls the movement of the main poppet. The main poppet has an opening portion that communicates the 2 nd port with the control chamber. A pilot piston is movably received in the opening portion of the main poppet and has a pilot passage therein. The 1 st disc spring biases the pilot piston against the main poppet. The pilot valve element operates to open and close the pilot passage. The actuator is operatively coupled to move the pilot valve element.

Disclosure of Invention

Problems to be solved by the invention

In the motor-operated valve described in patent document 1, the valve body needs to be held at a predetermined position by a driving force generated by the motor. Therefore, if the pressure of the fluid flowing between the 1 st port and the 2 nd port rises, the driving force for holding the valve body increases in proportion to the pressure. As a result, there is a problem that a large electric power is required for holding the valve body. On the other hand, in the pilot-operated valve described in patent document 2, the position of the pilot valve element is controlled by the 1 st disc spring and the actuator. Therefore, the positional accuracy of the valve element is likely to vary due to hysteresis of the spring, the actuator, and other devices. Further, the pressure of the oil at the 1 st port or the 2 nd port acts directly on the pilot valve element when the valve is closed, depending on the flow direction of the oil. Therefore, in order to maintain the pilot valve element in the closed valve state, a large driving force is required for the actuator, which causes a problem of an increase in power consumption.

The present invention has been made in view of the above-described problems, and an object thereof is to provide an electrically driven flow control valve capable of controlling the flow rate of a fluid flowing between two ports while suppressing a high pressure of the fluid acting on a sub-valve body connected to an electric motor.

Means for solving the problems

An electrically driven flow rate control valve according to an aspect of the present invention includes: a housing having a1 st fluid chamber, a2 nd fluid chamber, a fluid chamber communication port for communicating the 1 st fluid chamber and the 2 nd fluid chamber, and a cylinder portion, wherein the housing is formed with a1 st inlet/outlet through which a fluid can be introduced and discharged between the outside of the housing and the 1 st fluid chamber, and a2 nd inlet/outlet through which a fluid can be introduced and discharged between the outside of the housing and the 2 nd fluid chamber; an electric motor; a main valve body having a main valve body distal end portion capable of closing the fluid chamber communication port, the main valve body being accommodated in the cylinder portion so as to be movable along a predetermined axial direction between a main valve body open position and a main valve body closed position, and a back pressure chamber capable of allowing a fluid to enter and exit from the cylinder portion, the main valve body being configured such that, if the main valve body is disposed at the main valve body open position, the fluid chamber communication port is opened by the main valve body distal end portion to allow a fluid to flow between the 1 st fluid chamber and the 2 nd fluid chamber, and, if the main valve body is disposed at the main valve body closed position, the fluid chamber communication port is closed by the main valve body distal end portion to block a fluid flow between the 1 st fluid chamber and the 2 nd fluid chamber; a biasing mechanism for biasing the main valve body toward the main valve body closing position; a1 st communication passage capable of communicating the 1 st fluid chamber and the back pressure chamber with each other; a2 nd communication passage capable of communicating the 2 nd fluid chamber and the back pressure chamber with each other; a switching mechanism capable of changing a state between a1 st communication state and a2 nd communication state, the 1 st communication state being a state in which the flow of the fluid in the 1 st communication passage is enabled and the flow of the fluid in the 2 nd communication passage is blocked when the pressure of the fluid in the 1 st fluid chamber is higher than the pressure of the fluid in the 2 nd fluid chamber, the 2 nd communication state being a state in which the flow of the fluid in the 2 nd communication passage is enabled and the flow of the fluid in the 1 st communication passage is blocked when the pressure of the fluid in the 1 st fluid chamber is lower than the pressure of the fluid in the 2 nd fluid chamber; a1 st flow rate adjusting mechanism disposed in the 1 st communication passage and configured to adjust a flow rate of the fluid such that the flow rate of the fluid flowing from the 1 st fluid chamber toward the back pressure chamber is decreased; a2 nd flow rate adjusting mechanism which is arranged in the 2 nd communication passage and adjusts the flow rate of the fluid so as to reduce the flow rate of the fluid flowing from the 2 nd fluid chamber to the back pressure chamber; and a sub-valve body accommodated in the back pressure chamber, the sub-valve body having a sub-valve body flow passage communicating with the outside of the housing and a sub-valve body communication port communicating the back pressure chamber with the sub-valve body flow passage, the sub-valve body being movable relative to the main valve body in the axial direction between a sub-valve body open position and a sub-valve body closed position by a driving force generated by the electric motor, opening the sub valve body communication port to allow the fluid in the back pressure chamber to be discharged to the outside of the housing through the sub valve body flow path if the sub valve body is disposed at the sub valve body opening position, when the sub valve body is disposed at the sub valve body closing position, the sub valve body communication port is closed to block the flow of the fluid between the back pressure chamber and the sub valve body flow passage, and the main valve body is allowed to be arranged at the main valve body closing position by receiving the biasing force of the biasing mechanism.

According to this configuration, the position (opening/closing operation) of the main valve body can be controlled with high accuracy by the position control of the sub valve body by the electric motor. Further, a1 st flow rate adjusting mechanism and a2 nd flow rate adjusting mechanism are disposed in the 1 st communication passage and the 2 nd communication passage. Therefore, the high pressures of the 1 st fluid chamber and the 2 nd fluid chamber are suppressed from being directly applied to the sub valve body, and the pressure required for driving the main valve body is supplied to the back pressure chamber. As a result, it is not necessary to drive the sub-valve body against these high pressures, and the electric motor may generate a driving force for relatively moving the sub-valve body with respect to the main valve body. Therefore, the electric driven flow control valve can be reduced in power consumption, output and size. Further, the switching mechanism automatically selects the high pressure side of the 1 st fluid chamber and the 2 nd fluid chamber, and can supply the fluid to the back pressure chamber for the opening and closing operation of the main valve body. Therefore, it is not necessary to provide a plurality of directional control valves for supplying the fluid to the back pressure chamber, and the bidirectional fluid flow between the 1 st port and the 2 nd port can be easily controlled.

In the above-described structure, it is preferable that the fluid chamber communication port has a circular shape when viewed in the axial direction; the main valve body has a conical tip end portion capable of closing the fluid chamber communication port along the axial direction.

According to this configuration, the main valve body is driven so that the distal end portion of the main valve body enters the fluid chamber communication port, whereby the inflow and outflow of the fluid can be stably prevented over the entire circumferential direction of the distal end portion of the main valve body.

In the above configuration, it is preferable that the main valve body has an internal space which communicates with the back pressure chamber on the opposite side to the front end of the main valve body and is formed in a cylindrical shape along the axial direction and into which the sub valve body can enter, and a front end inner wall portion on the front end side of the main valve body which defines the internal space; the sub valve body has a cylindrical portion disposed at least at an end portion on the front end inner wall portion side, and the sub valve body communication port is opened in the cylindrical portion; the front end inner wall portion has a recessed portion that allows the cylindrical portion of the sub-valve body to enter and is in close contact with the cylindrical portion over the entire circumferential direction.

According to this configuration, the cylindrical portion of the sub valve body is inserted into the recessed portion of the main valve body, whereby the discharge of the fluid from the back pressure chamber to the sub valve body flow passage can be prevented. Further, since the sub-valve body communication port is opened in the cylindrical portion of the sub-valve body, it is difficult for the pressure of the back pressure chamber to be applied to the sub-valve body communication port. Therefore, the consumption of a large amount of electric power for maintaining the position of the sub-valve body at the time of closing the valve is suppressed.

In the above-described configuration, it is preferable that the sub-valve body communication port is opened in an end surface of the cylindrical portion of the sub-valve body, the end surface intersecting with the axial direction.

According to this configuration, by pressing the lower end portion of the cylindrical portion of the sub valve body against the recessed portion of the main valve body, the discharge of the fluid from the back pressure chamber to the sub valve body flow passage can be stably prevented.

In the above-described configuration, it is preferable that the recessed portion of the distal end inner wall portion is formed in a conical shape, and if the sub-valve body is disposed at the sub-valve body closing position, an inclined surface of the recessed portion is in close contact with a circumferential edge of the end surface of the cylindrical portion over the entire circumferential direction.

According to this configuration, by pressing the lower end portion of the cylindrical portion of the sub valve body against the recessed portion of the main valve body, the discharge of the fluid from the back pressure chamber to the sub valve body flow passage can be more stably prevented.

In the above-described configuration, it is preferable that the sub-valve body communication port is opened in a side surface of the cylindrical portion of the sub-valve body extending in the axial direction; the concave portion is formed in a cylindrical shape so that the cylindrical portion can enter; the sub-valve body communication port is disposed at the following position in the cylindrical portion: and a position where the sub valve body communication port is closed if the cylindrical portion enters the recessed portion in response to the movement of the sub valve body, and the sub valve body communication port is communicated with the back pressure chamber if the cylindrical portion is separated from the recessed portion in response to the movement of the sub valve body.

According to this configuration, the cylindrical portion of the sub valve body is inserted into the recessed portion of the main valve body, whereby the discharge of the fluid from the back pressure chamber to the sub valve body flow passage can be prevented. Further, the opening area of the sub-valve communication port can be adjusted in accordance with the relative movement of the sub-valve with respect to the main valve, and the opening and closing operation of the main valve can be controlled with high accuracy.

In the above-described configuration, it is preferable that the 1 st flow rate adjustment mechanism and the 2 nd flow rate adjustment mechanism are orifices respectively disposed in the 1 st communication passage and the 2 nd communication passage.

According to this configuration, the high pressures in the 1 st fluid chamber and the 2 nd fluid chamber are suppressed from being applied to the back pressure chamber and the sub valve body by the simple orifice structures formed in the respective communication passages. As a result, the power consumption of the electric motor can be reduced.

In the above-described configuration, it is preferable that the 1 st flow rate adjustment mechanism and the 2 nd flow rate adjustment mechanism are respectively disposed between the 1 st fluid chamber and the switching mechanism and between the 2 nd fluid chamber and the switching mechanism.

According to this configuration, the flow rate required for each communication passage can be individually set.

Effects of the invention

According to the present invention, it is possible to provide an electrically driven flow control valve capable of controlling the flow rate of a fluid flowing between two ports while suppressing a high pressure of the fluid acting on a sub-valve body connected to an electric motor.

Drawings

Fig. 1 is a sectional view of an electrically driven flow rate control valve according to an embodiment of the present invention.

Fig. 2 is a hydraulic circuit diagram of the electrically driven flow control valve of fig. 1.

Fig. 3 is a cross-sectional view showing a state in which a main valve body of the electrically driven flow rate control valve of fig. 1 is opened.

Fig. 4 is a schematic diagram for explaining the force acting on the main valve body of the electrically driven flow control valve of fig. 1.

Fig. 5 is a graph showing a relationship between an opening area of a sub valve body of the electrically driven flow control valve of fig. 1 and a relative distance Xi between a main valve body and the sub valve body.

Fig. 6 is a sectional view of an electrically driven flow rate control valve according to a modified embodiment of the present invention.

Fig. 7 is a sectional view showing a state in which a main valve body of the electrically driven flow rate control valve of fig. 6 is opened.

Fig. 8 is a sectional view of an electrically driven flow rate control valve according to another modified embodiment of the present invention.

Fig. 9 is a sectional view of an electrically driven flow rate control valve according to another modified embodiment of the present invention.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a sectional view of a flow rate control valve 1 (electrically driven flow rate control valve) according to the present embodiment. Fig. 2 is a hydraulic circuit diagram of the flow control valve 1 of fig. 1. In the drawings, the directions "up", "down", "left" and "right" are shown hereinafter, but the directions are shown for convenience of explanation of the structure of the flow rate control valve 1 according to the present embodiment, and are not intended to limit the usage form of the electrically driven flow rate control valve according to the present invention. The flow rate control valve 1 according to the present embodiment is a valve that controls the flow of hydraulic oil in both directions, and is used in a hydraulic circuit of a construction machine as an example.

Referring to fig. 1, a flow rate control valve 1 includes a housing 2, an elevation drive device 3, a supply switching valve 4 (switching mechanism), a main valve body 5, and a valve closing spring 6 (urging mechanism). The lifting drive device 3 includes an electric motor 31, a rotary lifter 32, and a sub-valve body 33. In the flow rate control valve 1, the main valve body 5 is moved by driving the lift driving device 3, and the flow rate of the working oil is controlled by communicating the 1 st port 2A and the 2 nd port 2B formed in the housing 2.

The housing 2 accommodates or holds the components of the flow rate control valve 1. In the present embodiment, the housing 2 has a substantially rectangular parallelepiped shape. The housing 2 has a1 st oil chamber 21 (1 st fluid chamber), a2 nd oil chamber 22 (2 nd fluid chamber), an oil chamber communication port 2C (fluid chamber communication port), and a cylinder portion 2S. The 1 st oil chamber 21 and the 2 nd oil chamber 22 allow working oil (fluid) to be contained therein. The 1 st oil chamber 21 is formed in the bottom of the housing 2. In the present embodiment, the 1 st oil chamber 21 is formed in a cylindrical shape (columnar shape) centered on a central axis CL extending in the vertical direction. The 2 nd oil chamber 22 is disposed above the 1 st oil chamber 21. The 2 nd oil chamber 22 has a rectangular parallelepiped shape extending in the horizontal direction. In fig. 1, the 2 nd oil chamber 22 is divided into a left portion and a right portion of the main valve body 5, but these portions communicate with each other via a portion adjacent to the main valve body 5 in the front-rear direction (direction orthogonal to the paper surface of fig. 1).

The oil chamber communication port 2C is formed in an upper end portion of the 1 st oil chamber 21, in other words, a lower end portion (bottom portion) of the 2 nd oil chamber 22, and communicates the 1 st oil chamber 21 and the 2 nd oil chamber 22 with each other. The oil chamber communication port 2C has a circular shape when viewed along the center axis CL. Further, a1 st port 2A (1 st inlet/outlet) and a2 nd port 2B (2 nd inlet/outlet) are formed in the lower surface portion and the right side surface portion of the casing 2, respectively. The 1 st port 2A can supply and discharge working oil between the outside of the housing 2 and the 1 st oil chamber 21. Similarly, the 2 nd port 2B can supply and discharge the working oil between the outside of the housing 2 and the 2 nd oil chamber 22.

The electric motor 31 is a member controlled by the control unit 7, and in the present embodiment, is rotatable about the center axis CL in the 1 st rotation direction and the 2 nd rotation direction opposite to the 1 st rotation direction.

The rotary lifter 32 is screwed to an output shaft of the electric motor 31 and is coupled to the sub-valve body 33, and converts a rotational force generated by the electric motor 31 into an axial moving force. As a result, if the electric motor 31 rotates, the sub valve body 33 moves (ascends and descends) in the up-down direction. For example, the rotary lifter 32 has a well-known ball screw mechanism and a highly accurate reduction gear inside.

The main valve body 5 has a cylindrical shape with an upper end opened. The main valve body 5 has a main valve body tip portion 5A, a cylindrical space 5S (internal space), and a tip inner wall portion 5S 1. The main valve body distal end portion 5A has a conical shape tapered downward, and can close the oil chamber communication port 2C from above along the axial direction. The cylindrical space 5S communicates with the back pressure chamber 20 on the opposite side of the main valve body tip portion 5A in the axial direction, and is formed in a cylindrical shape along the axial direction. As shown in fig. 1, the sub valve body 33 can enter the cylindrical space 5S. The distal end inner wall portion 5S1 is a part of the inner wall portion of the main valve body 5, and defines an end surface (bottom surface of the cylindrical space 5S) of the cylindrical space 5S on the main valve body distal end portion 5A side. In the present embodiment, the distal end inner wall portion 5S1 has a distal end concave portion 5B. As described later, the recessed portion 5B allows the cylindrical portion 33R of the sub-valve body 33 to enter and be in close contact with the cylindrical portion 33R over the entire circumferential direction. In particular, in the present embodiment, the recessed portion 5B is formed in a conical shape centered on the central axis CL as shown in fig. 1, and the inclined surface of the recessed portion 5B is in close contact with the end surface (peripheral edge) of the cylindrical portion 33R of the sub-valve body 33 over the entire circumferential direction.

The main valve body 5 is accommodated in the cylinder portion 2S so as to be movable along a central axis CL (a predetermined axial direction) between a main valve body open position (fig. 3) and a main valve body closed position (fig. 1). As shown in fig. 1, the main valve body 5 forms a back pressure chamber 20 into and out of which working oil can enter and exit between the cylinder 2S. When the main valve body 5 is disposed at the main valve body opening position, the main valve body distal end portion 5A opens the oil chamber communication port 2C, and the working oil is allowed to flow between the 1 st oil chamber 21 and the 2 nd oil chamber 22. Further, if the main valve body 5 is disposed at the main valve body closing position, the main valve body distal end portion 5A closes the oil chamber communication port 2C from above, and the flow of the working oil between the 1 st oil chamber 21 and the 2 nd oil chamber 22 is blocked.

Further, the housing 2 is formed with a1 st oil passage 23 (1 st communication passage), a2 nd oil passage 24 (2 nd communication passage), and a discharge oil passage 27. The 1 st oil passage 23 is an oil passage that can communicate the 1 st oil chamber 21 and the back pressure chamber 20 with each other. Similarly, the 2 nd oil passage 24 is an oil passage that can communicate the 2 nd oil chamber 22 and the back pressure chamber 20 with each other. In the present embodiment, the back pressure chamber 20 side of the 1 st oil passage 23 and the back pressure chamber 20 side of the 2 nd oil passage 24 are merged with each other at the merged oil passage 26. As will be described later, the discharge oil passage 27 guides the hydraulic oil discharged from the back pressure chamber 20 through the sub-valve body 33 to the outside of the housing 2. At a distal end portion of the discharge oil passage 27 in the housing 2, a discharge port 27S is arranged.

The valve closing spring 6 biases the main valve body 5 along the center axis CL toward the main valve body closing position. In the present embodiment, as shown in fig. 1, the valve closing spring 6 is disposed so as to be fitted to the sub valve body 33 outside the back pressure chamber 20 and the cylindrical space 5S of the main valve body 5. The upper end of the valve closing spring 6 is fixed to the inner wall of the housing 2 (the upper surface of the back pressure chamber 20), and the lower end of the valve closing spring 6 is fixed to the front end inner wall 5S1 of the main valve body 5.

The supply switching valve 4 is a directional switching valve and is disposed near the inlet of the merged oil passage 26 of the 1 st oil passage 23 and the 2 nd oil passage 24. The supply switching valve 4 can change its state between the 1 st communication state and the 2 nd communication state. Specifically, when the pressure of the working oil in the 1 st oil chamber 21 is higher than the pressure of the working oil in the 2 nd oil chamber 22, the supply switching valve 4 allows the working oil in the 1 st oil passage 23 to flow therethrough, and blocks the working oil in the 2 nd oil passage 24 from flowing therethrough (1 st communication state). On the other hand, when the pressure of the working oil in the 1 st oil chamber 21 is lower than the pressure of the working oil in the 2 nd oil chamber 22, the supply switching valve 4 allows the fluid in the 2 nd oil passage 24 to flow therethrough, and blocks the fluid in the 1 st oil passage 23 from flowing therethrough (2 nd communication state). The working oil can be automatically supplied from the high-pressure side of the 1 st oil chamber 21 and the 2 nd oil chamber 22 to the back-pressure chamber 20 by the supply switching valve 4.

As shown in fig. 1, the 1 st oil passage 23 has a1 st orifice 23S (1 st flow rate adjustment mechanism), and the 2 nd oil passage 24 has a2 nd orifice 24S (2 nd flow rate adjustment mechanism). The 1 st orifice 23S is disposed between the 1 st oil chamber 21 and the supply switching valve 4. The 1 st orifice 23S is a member that causes a pressure loss in the 1 st oil passage 23, and adjusts the flow rate of the working oil so as to decrease the flow rate of the working oil flowing from the 1 st oil chamber 21 to the back pressure chamber 20. Similarly, the 2 nd orifice 24S is a member that causes pressure loss in the 2 nd oil passage 24, and is disposed between the 2 nd oil chamber 22 and the supply switching valve 4. The 2 nd orifice 24S adjusts the flow rate of the hydraulic oil so that the flow rate of the hydraulic oil flowing from the 2 nd oil chamber 22 to the back pressure chamber 20 decreases. The pressure of the fluid necessary to drive the main valve element 5 can be supplied to the back pressure chamber 20 through the 1 st orifice 23S and the 2 nd orifice 24S, and the supply of excessive pressure to the back pressure chamber 20 can be suppressed.

The sub valve body 33 is accommodated in the back pressure chamber 20 and the cylindrical space 5S of the main valve body 5. In the present embodiment, the sub-valve body 33 is formed of a circular tube member linearly extending on the center axis CL. In other words, the sub-valve body 33 has a cylindrical portion 33R disposed at least at its front end portion (lower end portion, end portion on the front end inner wall portion 5S1 side). The upper end of the sub valve body 33 is connected to the rotary lifter 32. The sub-valve body 33 has a sub-valve body oil passage 33S (sub-valve body flow passage) and a sub-valve body communication port 33T. The sub-valve-body oil passage 33S is an oil passage extending in the vertical direction inside the sub-valve body 33. The upper end portion of the sub-valve oil passage 33S communicates with the discharge oil passage 27. The sub-valve body communication port 33T opens at a lower end surface (end surface) of the cylindrical portion 33R of the sub-valve body 33. The sub-valve body communication port 33T communicates the back pressure chamber 20 with the sub-valve body oil passage 33S.

The sub-valve body 33 is relatively movable in the axial direction with respect to the main valve body 5 between a sub-valve body open position and a sub-valve body closed position by a driving force generated by the electric motor 31. When the sub-valve body 33 is disposed at the sub-valve body open position, the lower end portion (the cylindrical portion 33R) of the sub-valve body 33 is spaced upward from the front end inner wall portion 5S1 of the main valve body 5. As a result, the sub-valve body 33 opens the sub-valve body communication port 33T, allowing the working oil in the back pressure chamber 20 to be discharged to the outside of the housing 2 through the sub-valve body oil passage 33S and the discharge oil passage 27. On the other hand, if the sub-valve body 33 is disposed at the sub-valve body closing position, the lower end portion of the sub-valve body 33 abuts against the inclined surface portion of the recess 5B of the main valve body 5 over the entire circumferential direction. As a result, the sub-valve body 33 closes the sub-valve body communication port 33T, and the flow of the working oil between the back pressure chamber 20 and the sub-valve body oil passage 33S is blocked. As will be described later, the sub-valve body 33 disposed at the sub-valve body closing position allows the main valve body 5 to be disposed at the main valve body closing position by receiving the biasing force of the valve closing spring 6.

Fig. 3 is a cross-sectional view showing a state in which the main valve body 5 of the flow rate control valve 1 of fig. 1 is opened. Fig. 4 is a schematic diagram for explaining a force acting on the main valve body 5 of the flow control valve 1 of fig. 1. Fig. 5 is a graph showing a relationship between the opening area between the sub valve body 33 and the main valve body 5 of the flow control valve 1 of fig. 1 and the relative distance Xi between the main valve body 5 and the sub valve body 33.

In the present embodiment, the electric motor 31 controlled by the control unit 7 is rotationally driven as a drive source. The rotary lifter 32 can convert the rotational motion and the translational motion, and convert the rotational motion of the electric motor 31 into the translational motion (vertical direction in fig. 1), and can move in the translational motion together with the sub valve body 33 coupled to the rotary lifter 32. Then, the main valve body 5 moves in a translational motion in conjunction with the movement of the sub valve body 33, and the opening area between the 1 st oil chamber 21 and the 2 nd oil chamber 22 changes in the oil chamber communication port 2C, thereby adjusting the flow rate of the working oil. The principle of operation of the flow control valve 1 will be described below by taking as an example a case where working oil flows from the 1 st port 2A to the 2 nd port 2B.

Referring to fig. 4, the force applied to the main valve body 5 will be described. In a state where the main valve body distal end portion 5A of the main valve body 5 closes the oil chamber communication port 2C, a pressure receiving area (an area projected in a direction parallel to the central axis CL) of the main valve body distal end portion 5A on the 1 st oil chamber 21 side is defined as a1, and a pressure receiving area of the main valve body distal end portion 5A on the 2 nd oil chamber 22 side is defined as a 2. Further, the shape of the main valve body 5 is set so as to satisfy A1 < A3. Further, a pressure receiving area of the upper end portion of the main valve body 5, i.e., the back pressure chamber 20 side is defined as a 3. Further, the pressure of the 1 st oil chamber 21 is defined as P1, the pressure of the 2 nd oil chamber 22 is defined as P2, and the pressure of the back pressure chamber 20 is defined as P3. Further, a stroke (amount of displacement) of the main valve body 5 in the axial direction parallel to the center axis CL is defined as X, a stroke (amount of displacement) of the sub valve body 33 is defined as Xr, and a relative stroke (amount of relative displacement) of the sub valve body 33 with respect to the main valve body 5 is defined as Xi (= X-Xr). Further, the opening area of the main valve body 5 that opens the oil chamber communication port 2C is defined as g (x), and the opening area between the sub valve body 33 formed at the lower end portion of the sub valve body 33 and the main valve body 5 is defined as h (xi). The opening areas G (X), H (xi) are each a function of the stroke X, Xi. The opening areas of the 1 st orifice 23S and the 2 nd orifice 24S, which are set in advance, are defined as Am. Further, a flow rate of the hydraulic oil passing through the oil chamber communication port 2C from the 1 st oil chamber 21 to the 2 nd oil chamber 22 is defined as Q1, and a flow rate of the hydraulic oil passing through the sub valve body communication port 33T from the back pressure chamber 20 to the discharge port 27S is defined as Q2. Further, the spring constant of the valve closing spring 6 is defined as ks, and the spring setting force of the valve closing spring 6 (the force that urges the main valve body 5 in the initial state) is defined as Fs 0.

In consideration of the balance of the forces acting on the main valve body 5 in the axial direction, the forces Fa and Fb applied to the main valve body 5 in the valve opening direction (upward in fig. 1) by the operating oil can be expressed by the following expressions 1 and 2.

Fa = P1 × a1 … (formula 1)

Fb = P2 × a2 … (formula 2).

Similarly, a force Fc applied to the main valve body 5 in the valve closing direction (downward in fig. 1) by the working oil can be expressed by the following formula 3.

Fc = P3 × A3 … (formula 3).

The spring force Fs that the closing spring 6 applies to the main valve body 5 can be expressed by the following expression 4.

Fs = Fs0+ ks × X … (formula 4).

The force F acting on the main valve body 5 can be expressed by the following equation 5.

F = Fa + Fb- (Fc + Fs) … (formula 5).

According to equation 5, main valve body 5 is stationary when F = 0. When F > 0, the main valve body 5 moves in the valve opening direction, and when F < 0, the main valve body 5 moves in the valve closing direction.

The operation of opening the main valve body 5 when the pressure of the 1 st oil chamber 21 is higher than the pressure of the 2 nd oil chamber 22 will be described.

< initial state (X = 0) >

In the closed state in which the main valve body 5 closes the oil chamber communication port 2C, the strokes of the main valve body 5 and the sub valve body 33 are both 0. That is, the following relational expression 6 holds.

X =0, Xr =0, Xi = X-Xr =0 … (formula 6).

In this case, as shown in fig. 5, since the opening area h (x) of the sub-valve body 33 is 0, the flow rate Q2 of the hydraulic oil discharged from the discharge port 27S is also 0. Here, the flow rate Q2 of the working oil discharged from the discharge port 27S is equal to the flow rate of the working oil flowing from the 1 st oil chamber 21 into the back pressure chamber 20. Since the flow rate of the hydraulic oil passing through the 1 st orifice 23S is also 0, the pressure of the 1 st oil chamber 21 and the pressure of the back pressure chamber 20 become equal to each other (P1 = P3). Therefore, formula 5 can be replaced with formula 7 below.

F = P1 × a1+ P2 × a 2- (P3 × A3+ Fs) < 0 … (formula 7).

That is, regardless of the pressures of the 1 st oil chamber 21 and the 2 nd oil chamber 22, the main valve body 5 is always pressed against the oil chamber communication port 2C, and the flow of the working oil from the 1 st oil chamber 21 to the 2 nd oil chamber 22 can be blocked. At this time, since the sub valve body 33 is pressed against the main valve body 5 to keep the relative position of the two at a constant level, the electric motor 31 can block the flow between the 1 st oil chamber 21 and the 2 nd oil chamber 22 without consuming electric power.

< opening operation >

From the initial state described above, if the control unit 7 rotates the electric motor 31 and moves the sub valve body 33 upward, the relative position of the main valve body 5 and the sub valve body 33 changes. As a result, a gap is formed between the lower end portion of the sub-valve body 33 and the concave portion 5B of the main valve body 5, and the hydraulic oil in the back pressure chamber 20 is discharged from the sub-valve body communication port 33T through the sub-valve body oil passage 33S and the discharge oil passage 27. That is, the flow rate Q2 through the discharge oil passage 27 occurs. As a result, the working oil of the flow rate Q2 flows into the back pressure chamber 20 from the 1 st oil chamber 21. At this time, since the working oil of the flow rate Q2 passes through the 1 st orifice 23S, the following expression 8 is satisfied.

Q2＝C×Am×

（P1－P3）＝C×H（Xi）

(P3) … (formula 8).

Further, C is a flow rate coefficient determined by the shape of the 1 st orifice 23S and various factors of the fluid. From equation 8, the following equation 9 is derived.

P3＝Am²／（H（Xi）²＋Am²) XP 1 … (formula 9).

On the other hand, formula 5 can be expressed as in the following formula 10 from formula 1 to formula 4.

F = P1 × a1+ P2 × a 2- (P3 × A3+ (Fs 0+ ks × X)) … (formula 10).

According to expressions 9 and 10, the pressure P3 of the back pressure chamber 20 becomes smaller as the stroke Xi of the sub-valve body 33 becomes larger. As a result, the force F applied to the main valve body 5 increases, and the main valve body 5 is pushed up in the valve opening direction by the pressure difference. The 1 st oil chamber 21 and the 2 nd oil chamber 22 communicate with each other via the oil chamber communication port 2C, and working oil can be circulated. At this time, according to equation 10, the position of the main valve body 5 is held in a state where the pressure P3 of the back pressure chamber 20 such as F =0, in other words, the opening area h (xi) of the sub valve body 33 such as F =0 is obtained.

When the flow of the working oil is described with reference to fig. 1 and 3, if the electric motor 31 is driven by the control unit 7 from the state of fig. 1, the sub-valve 33 moves upward as indicated by an arrow D1 in fig. 3. As a result, the sub-valve body communication port 33T is disengaged from the recess 5B (fig. 1), the back pressure chamber 20 and the sub-valve body oil passage 33S communicate with each other via the sub-valve body communication port 33T, and the hydraulic oil is discharged from the back pressure chamber 20 (arrows D2, D3). The opening area of the sub-valve body communication port 33T increases according to the amount of movement of the sub-valve body 33, and is fixed in the end (see fig. 5). As a result, the working oil flows into the back pressure chamber 20 from the 1 st oil chamber 21 (fig. 1) via the 1 st oil passage 23 (arrow D4). Then, the balance between the pressure difference between the back pressure chamber 20 and the 1 st oil chamber 21 and the biasing force of the valve closing spring 6 changes, and the main valve body 5 moves upward (arrow D5). As a result, the working oil flows from the 1 st oil chamber 21 into the 2 nd oil chamber 22 (arrow D6).

As described above, in the present embodiment, when the main valve body 5 is opened, the high pressure of the hydraulic oil in the 1 st oil chamber 21 does not directly act on the sub valve body 33. Therefore, the electric motor 31 may generate a driving force for moving the sub-valve body 33 including inertia and frictional resistance of the sub-valve body 33. Therefore, a large electric power is not required in the electric motor 31 to hold the sub valve body 33 against the pressure of the 1 st oil chamber 21. In the above description, the self weight of the main valve body 5 is regarded as zero. The pressure of the hydraulic oil acting on the main valve body 5 is 650N (66 kg), for example, and the weight of the main valve body 5 is 0.2kg, so the weight of the main valve body 5 can be regarded as zero. Further, when the weight of the main valve body 5 is larger, the pressure receiving areas a1 and a2 are increased, and therefore the same effect as described above is obtained.

< closing operation >

In the valve-opened state described above, if the control unit 7 rotates the electric motor 31 in the 2 nd rotation direction and moves the sub-valve body 33 downward, the stroke amount Xi of the sub-valve body 33 decreases, and the flow rate Q2 of the hydraulic oil discharged from the back pressure chamber 20 to the discharge oil passage 27 decreases. As a result, if the pressure P3 of the back pressure chamber 20 rises and F < 0 is obtained in equation 10, the main valve body 5 is pressed downward by the pressure difference and moves in the valve closing direction. Similarly to the valve opening operation described above, if the relative position Xi where F =0 is obtained in equation 10, the main valve body 5 is stopped. Further, if the sub valve body 33 is lowered by the electric motor 31 and moved to the lowermost position, the main valve body 5 is pressed against the oil chamber communication port 2C, and the flow of the working oil between the 1 st oil chamber 21 and the 2 nd oil chamber 22 is blocked. Further, if the main valve body 5 is disposed at the main valve body closing position (fig. 1), the pressure of the back pressure chamber 20 does not directly act on the lower end surface of the sub valve body 33 (sub valve body communication port 33T). As a result, the sub-valve 33 is prevented from being pressed upward by the pressure of the back pressure chamber 20. Therefore, it is not necessary to hold the sub-valve body 33 against the pressure of the back pressure chamber 20 when the valve is closed, and the power consumption of the electric motor 31 is reduced.

When the pressure of the 2 nd oil chamber 22 is higher than that of the 1 st oil chamber 21 and the working oil flows from the 2 nd oil chamber 22 to the 1 st oil chamber 21 through the oil chamber communication port 2C, the working oil is supplied from the 2 nd oil chamber 22 to the back pressure chamber 20 through the supply switching valve 4. At this time, the working oil passes through the 2 nd orifice 24S, and the application of high pressure to the sub valve body 33 is suppressed. The opening area of the 1 st orifice 23S and the opening area of the 2 nd orifice 24S do not need to be set to the same area, but may be set to any area. That is, the valve opening condition of the main valve body 5 may be set to be different between the case where the working oil flows from the 1 st port 2A to the 2 nd port 2B and the case where the working oil flows from the 2 nd port 2B to the 1 st port 2A. In this case, the pressure P2 of the 2 nd oil chamber 22 acts on the pressure receiving area a2, and the main valve body 5 is moved in the valve opening direction. Therefore, in the above-described expressions 1 to 10, the valve opening operation and the valve closing operation can be similarly controlled by replacing the pressure receiving area a1 with a2 and replacing the pressure P1 with P2.

As described above, in the present embodiment, the position (opening/closing operation) of the main valve body 5 can be controlled with high accuracy by the position control of the sub valve body 33 by the electric motor 31. In particular, in addition to the high-precision rotation control of the electric motor 31 itself, the control deviation of the sub-valve body 33 (main valve body 5) can be reduced in accordance with the reduction gear ratio of the rotary lifter 32. In addition, a1 st orifice 23S and a2 nd orifice 24S are disposed in the 1 st oil passage 23 and the 2 nd oil passage 24. Therefore, the high pressure of the 1 st oil chamber 21 and the 2 nd oil chamber 22 is suppressed from being directly applied to the sub valve body 33, and the pressure required for driving the main valve body 5 is supplied to the back pressure chamber 20. As a result, it is not necessary to drive the sub-valve body 33 against these high pressures, and the electric motor 31 may generate a driving force for relatively moving the sub-valve body 33 with respect to the main valve body 5. Therefore, the flow rate control valve 1 can be reduced in power consumption, output, and size. In order to stably realize the valve opening and closing operation of the main valve body 5 as described above, it is preferable that the pressure receiving area of the main valve body 5 satisfies a relationship of a1 < A3.

Further, in the present embodiment, the supply switching valve 4 automatically selects the high pressure side of the 1 st oil chamber 21 (the 1 st port 2A) and the 2 nd oil chamber 22 (the 2 nd port 2B), and can supply the hydraulic oil to the back pressure chamber 20 for the opening and closing operation of the main valve body 5. Therefore, it is not necessary to provide a plurality of directional control valves for supplying the hydraulic oil to the back pressure chamber 20, and the flow of the hydraulic oil between the 1 st port 2A and the 2 nd port 2B can be controlled in both directions.

In the present embodiment, the oil chamber communication port 2C of the housing 2 has a circular shape when viewed in the axial direction of the central axis CL, and the main valve body distal end portion 5A of the main valve body 5 has a conical shape capable of closing the oil chamber communication port 2C. Therefore, by driving the main valve body 5 so that the main valve body distal end portion 5A enters the oil chamber communication port 2C, the inflow and outflow of the working oil can be stably prevented in the entire circumferential direction of the main valve body distal end portion 5A around the center axis CL.

Further, in the present embodiment, by pressing (causing to enter) the lower end portion of the cylindrical portion 33R of the sub-valve body 33 into the recess portion 5B of the main valve body 5, the discharge of the hydraulic oil from the back pressure chamber 20 to the discharge oil passage 27 can be prevented. Therefore, the pressure of the back pressure chamber 20 does not act in the sub-valve body 33, and therefore, the electric power of the electric motor 31 can be suppressed. Further, since the sub-valve body communication port 33T is disposed on the lower end surface (end surface intersecting the axial direction) of the cylindrical portion 33R of the sub-valve body 33, the cylindrical portion 33R is pressed against the recessed portion 5B, and the discharge of the working oil can be stably prevented. Further, the lower end portion of the cylindrical portion 33R has a cylindrical shape (straight pipe shape), and by abutting against the conical concave portion 5B, the sealing function is maintained in the entire circumferential direction around the center axis CL, and the inflow and outflow of the working oil can be prevented. As a result, the discharge of the working oil can be prevented more stably. Further, since the sub-valve body communication port 33T is opened in the cylindrical portion 33R of the sub-valve body 33, the pressure of the back pressure chamber 20 is less likely to be applied to the sub-valve body communication port 33T. In particular, since the lower end surface of the cylindrical portion 33R of the sub-valve body 33 is disposed at the bottom of the cylindrical space 5S of the main valve body 5, the pressure of the back pressure chamber 20 is less likely to act on the lower end surface of the cylindrical portion 33R of the sub-valve body 33. Therefore, the consumption of a large amount of electric power for maintaining the position of the sub-valve body 33 during valve closing is suppressed.

In the present embodiment, the 1 st orifice 23S and the 2 nd orifice 24S are disposed in the 1 st oil passage 23 and the 2 nd oil passage 24, respectively. Therefore, the high pressures of the 1 st oil chamber 21 and the 2 nd oil chamber 22 are suppressed from being directly applied to the back pressure chamber 20 and the sub valve body 33 by the simple orifice structures formed in the respective oil passages. As a result, the power consumption of the electric motor 31 can be reduced. Further, since the individual orifices are provided in the respective oil passages, the flow rates required for the respective oil passages can be individually set. In addition, when the flow rates required for the respective oil passages are the same, in other words, when the opening diameters of the 1 st orifice 23S and the 2 nd orifice 24S are the same, a single common orifice (flow rate adjustment mechanism) may be provided between the supply switching valve 4 and the back pressure chamber 20.

The flow rate control valve 1 (electrically driven flow rate control valve) according to the embodiment of the present invention is described above. The present invention is not limited to these embodiments. As the electrically driven flow rate control valve according to the present invention, there may be a modified embodiment as described below.

(1) In the above-described embodiment, the sub-valve body communication port 33T is opened in the lower end surface of the cylindrical portion 33R of the sub-valve body 33, and the conical concave portion 5B is provided in the front end inner wall portion 5S1 of the main valve body 5. The recess 5B in fig. 1 may be formed in a cylindrical shape similarly to the lower end portion of the cylindrical portion 33R. In this case, the sub-valve body communication port 33T can be closed by the lower end portion of the cylindrical portion 33R entering the cylindrical recess portion 5B. The sub-valve body communication port 33T is not limited to the one opened in the lower end surface of the cylindrical portion 33R. Fig. 6 is a sectional view of an electrically driven flow rate control valve 1A according to a modified embodiment of the present invention. Fig. 7 is a cross-sectional view showing a state in which the main valve body 5 of the electrically driven flow rate control valve 1A of fig. 6 is opened.

In the present modified embodiment, the arrangement of the sub-valve body communication port 33P and the shape of the concave portion 5B of the main valve body 5 are different from those of the above-described embodiment, and therefore the description will be given centering on the difference. The front end inner wall portion 5S1 of the main valve body 5 has a recessed portion 5B that allows the cylindrical portion 33R of the sub valve body 33 to enter and be in close contact with the entire circumferential direction. The recess 5B has a cylindrical shape, and the inner diameter of the recess 5B is set slightly larger than the outer diameter of the cylindrical portion 33R. On the other hand, a pair of left and right sub-valve body communication ports 33P are opened in a circular shape on a side surface (circumferential surface) of the cylindrical portion 33R. The pair of sub-valve body communication ports 33P communicate with the sub-valve body oil passage 33S. The opening shape of the sub-valve body communication port 33P may be other shapes.

When the cylindrical portion 33R enters the recessed portion 5B in response to the downward movement of the sub-valve body 33, the valve body communication port 33P is closed by the inner circumferential surface of the recessed portion 5B. On the other hand, if the cylindrical portion 33R is disengaged from the recessed portion 5B in response to the upward movement of the sub-valve body 33, the pair of sub-valve body communication ports 33P communicate with the back pressure chamber 20. The sub-valve body communication port 33P is disposed at a position of the cylindrical portion 33R exhibiting such a function.

Specifically, if the control unit 7 drives the electric motor 31 from the state shown in fig. 6, the sub-valve body 33 moves upward as shown by an arrow D11 in fig. 7. As a result, the sub-valve body communication port 33P is disengaged from the recess 5B (fig. 6), the back pressure chamber 20 and the sub-valve body oil passage 33S communicate with each other through the sub-valve body communication port 33P, and the hydraulic oil is discharged from the back pressure chamber 20 (arrows D12, D13). The opening area of the sub-valve communication port 33P increases in accordance with the amount of movement of the sub-valve 33, and is fixed in the end (see fig. 5). As a result, the working oil flows into the back pressure chamber 20 from the 1 st oil chamber 21 (fig. 6) via the 1 st oil passage 23 (arrow D14). Further, as in the previous embodiment, the balance between the pressure difference between the back pressure chamber 20 and the 1 st oil chamber 21 and the biasing force of the valve closing spring 6 changes, and the main valve body 5 moves upward (arrow D15). As a result, the working oil flows from the 1 st oil chamber 21 into the 2 nd oil chamber 22 (arrow D16).

As described above, in the present modified embodiment, the discharge of the hydraulic oil from the back pressure chamber 20 to the sub-valve oil passage 33S can be prevented by the cylindrical portion 33R of the sub-valve 33 being inserted into the recessed portion 5B of the main valve 5. Further, the opening area of the sub-valve communication port 33P can be adjusted in accordance with the relative movement of the sub-valve 33 with respect to the main valve body 5, and the opening and closing operation of the main valve body 5 can be controlled with high accuracy. In the present modified embodiment, the sub-valve body communication port 33P is provided on the side surface of the cylindrical portion 33R. Therefore, the degree of freedom of the opening gain (the amount of change in h (Xi) with respect to Xi) of the sub-valve body communication port 33P can be increased. For example, by reducing the opening gain of the sub-valve communication port 33P, the amount of movement of the main valve body 5 relative to the amount of movement of the sub-valve 33 can be reduced, and therefore, the accuracy and stability of the valve opening operation can be improved. Further, in the present modified embodiment, it is also difficult to apply the pressure of the back pressure chamber 20 to the lower end surface of the sub-valve body 33, and the power consumption of the electric motor 31 is reduced.

The present invention is not limited to the above-described structure. For example, in the configuration shown in fig. 8 and 9, the inlet of the discharge oil passage 27 extends upward so as to maintain communication between the sub-valve oil passage 33S and the discharge oil passage 27 regardless of the rise or fall of the sub-valve 33.

Description of the reference numerals

1. 1A flow control valve

2 casing

20 back pressure chamber

21 st oil chamber (1 st fluid chamber)

22 nd oil chamber (2 nd fluid chamber)

23 oil passage 1 (communication passage 1)

23S 1 st orifice (1 st flow regulating mechanism)

24 nd oil circuit 2 (2 nd communication path)

24S 2 nd orifice (2 nd flow regulating mechanism)

26 confluence oil circuit

27 discharge oil path

27S discharge port

2A 1 st Port (1 st entrance)

2B 2 nd port (2 nd inlet and outlet)

2C oil chamber connecting port (fluid chamber connecting port)

2S cylinder part

3 lifting driving device

31 electric motor

32 rotating elevator

33 auxiliary valve body

33P auxiliary valve body communication port

33R cylindrical part

33S auxiliary valve body oil way

33T auxiliary valve body communication port

4 supply switching valve (switching mechanism)

5 Main valve body

5A main valve body front end part

5B recess

5S Cylinder space (inner space)

5S1 front end inner wall part

6 closing valve spring (forcing mechanism)

7 control part

CL center axis.