KR20020025712A - Control valve - Google Patents

Abstract

PURPOSE: A flow directional control valve is provided to widen space in an operating compartment and to facilitate constitution of a hydraulic circuit by making exhausting pilot pressured oil of high pressure possible without employing a shuttle valve and a pressure sensor. CONSTITUTION: A flow directional valve(3) is provided with a pilot pressured oil exhausting port(344) exhausting the pilot pressured oil of the high pressure in either the pilot pressured oil(P1 or P2) supplied to pilot ports(315,316). The pilot port and the pilot pressured oil exhausting port on the high pressure side are communicated in accordance with movement of a spool(4) moving by pressure difference of the pilot pressured oil, and the communication of the pilot port and the pilot pressured oil exhausting port on the low pressure side is shut off.

Description

Flow Direction Control Valve {CONTROL VALVE}

The present invention relates to a flow direction control valve for discharging high pressure pilot pressure oil among low pressure pilot pressure oil and high pressure pilot pressure oil supplied to the pilot port.

Various hydraulic actuators installed in the work vehicle are operated by the control device installed in the cab.

The operation of the hydraulic actuator will be described with reference to FIG. In FIG. 11, it is assumed that the hydraulic motor which operates the traveling body of a work vehicle as a hydraulic actuator. Independent traveling hydraulic motors are provided on the left and right traveling bodies of the work vehicle.

Pilot pressure oils P1 and P2 are supplied to the flow direction control valve 20 from the control apparatus 1. The pilot pressure oil P1 is supplied to one end side of the spool 4, and the pilot pressure oil P2 is supplied to the other end side of the spool 4. When the pressure of the pilot pressure oil P1 is smaller than the pressure of the pilot pressure oil P2 and the elastic bearing force of the spring 222, and the pressure of the pilot pressure oil P2 is the pressure of the pilot pressure oil P1 and the elasticity of the spring 221. When smaller than the bearing force, the spool 4 is in the neutral position.

When the lever 1a is tilted in the direction of the arrow A shown in Fig. 11, the pressure of the pilot pressure oil P2 is greater than the pressure of the pilot pressure oil P1 and the elastic bearing force of the spring 221, and the spool 4 Move leftward from the neutral position. The oil pressure supply unit 201 and the direction control port 204 communicate with each other through the cutout portion 41 and the conduit 202. The pressure oil supplied from the hydraulic pump to the pressure oil supply unit 201 is discharged from the direction control port 204 and supplied to the hydraulic motor. The hydraulic motor rotates forward.

When the lever 1a is tilted in the direction of the arrow B shown in FIG. 11, the pressure of the pilot pressure oil P1 is greater than the pressure of the pilot pressure oil P2 and the elastic bearing force of the spring 222, and the spool 4 is neutral. Move from the position to the drawing right direction. The oil pressure supply part 206 and the direction control port 209 communicate with each other through the cutout part 43 and the conduit 207. The hydraulic oil supplied from the hydraulic pump to the hydraulic oil supply unit 206 is discharged from the direction control port 209 and supplied to the hydraulic motor. The hydraulic motor reverses.

In addition, since the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is changed by changing the inclination movement amount of the lever 1a, the movement position of the spool 4 changes. Accordingly, the flow rate of the pressurized oil discharged from the direction control port 204 or the direction control port 209 changes. The hydraulic motor's rotation speed changes.

In this way, by operating the lever (1a) provided in the control device 1 to control the rotational direction and the rotational speed of the left and right hydraulic motor, it is possible to control the running speed and the traveling direction of the work vehicle.

By the way, when the work vehicle runs, the operation of the arm installed in the work vehicle is limited.

Referring to Fig. 11, the control device 1 is provided with a shuttle valve 1c in addition to the lever 1a and the PPC valve 1b. The shuttle valve 1c selects a high pressure pilot pressure oil from the pilot pressure oils P1 and P2 supplied from the PPC valve 1b and discharges it to the conduit 10. The pilot pressure oil of high pressure is supplied to the hydraulic pressure chamber 11 of the arm control part 15 via the conduit 10. The piston 12 moves from the full stroke position 12a of the arm control part 15 to the stroke restraint position 12b in accordance with the supply of the pilot pressure oil to the hydraulic pressure chamber 11. When the piston 12 is in the full stroke position 12a, the arm spool 13 can move to the full stroke position 12a. In this case, the flow rate of the pressurized oil supplied from the hydraulic pump to the arm becomes maximum. On the other hand, when the piston 12 is in the stroke restraint position 12b, the arm spool 13 can only move to the stroke restraint position 12b. As a result, the maximum amount of pressure oil is not supplied to the arm. Therefore, the work by the arm is restricted when the work vehicle is traveling.

Moreover, the operation | movement of an arm may be restrict | limited only when the pressure of the high pressure pilot pressure oil discharged from the shuttle valve 1c is measured by the pressure sensor which is not shown in figure, and a measured value exists in a predetermined range.

12 is a view showing a mode in which the control device and the shuttle valve are separately provided.

The control device 1 and the shuttle valve 2 shown in FIG. 12 are provided separately. The pilot pressure oil P1 discharged from the PPC valve 1b is supplied to one port of the shuttle valve 2 via the conduit 5 and the branch conduit 5 '. The pilot pressure oil P2 discharged from the PPC valve 1b is supplied to the other port of the shuttle valve 2 via the conduit 6 and the branch conduit 6 '. The shuttle valve 2 selects a high pressure pilot pressure oil from the pilot pressure oils P1 and P2 supplied from the PPC valve 1b and discharges it to the pipeline 10.

The control apparatus 1 shown in FIG. 11 is provided with the lever 1a, the PPC valve 1b, and the shuttle valve 1c, and the control apparatus 1 itself is large. In general, since the space in the cab of the work vehicle is limited, the smaller the control device 1 is desired.

Since the control device 1 'shown in FIG. 12 is not provided with the shuttle valve 1c, the control device 1' itself does not become as large as that, but a space for accommodating the shuttle valve 2 provided separately is required. Done. In addition, a pipe line is required between the control device 1 'and the shuttle valve 2, which complicates the construction of the hydraulic circuit.

In addition, the position of the port (hereinafter, referred to as "discharge port") for discharging the pilot pressure oil of the shuttle valves 1c and 2 is determined by the position where the shuttle valves 1c and 2 are arranged. Therefore, when the discharge port and the pressure receiving chamber 1 of the arm control unit 15 are disposed apart from each other, piping is required between the discharge port and the hydraulic pressure chamber 11, and the configuration of the hydraulic circuit becomes complicated.

In addition, when a pressure sensor is used, space for accommodating the pressure sensor is required. Further, piping is required between the shuttle valves 1c and 2 and the pressure sensor, and the construction of the hydraulic circuit becomes complicated.

As described above, in order to use the shuttle valves 1c and 2 and the pressure sensors, there is a problem that the space in the cab becomes narrow and the configuration of the hydraulic circuit becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and it is possible to discharge the high pressure pilot pressure oil without using a shuttle valve or a pressure sensor, thereby making the space in the cab wider and simplifying the construction of the hydraulic circuit. Shall be.

1 is a configuration diagram showing an embodiment of the present invention.

2 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is neutral.

3 is an enlarged cross-sectional structural view of a cover portion of the flow direction control valve.

4 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the left direction of the drawing.

5 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the right direction in the drawing.

6 is a cross-sectional structural view of the flow direction control valve, and illustrates a state in which the spool is neutral.

7 is a cross-sectional structural view of the flow direction control valve, in which the spool is in a left direction in the drawing.

8 is a cross-sectional structural view of the flow direction control valve, and illustrates a state in which the spool is in the right direction in the drawing.

9 is a cross-sectional structural view of the flow direction control valve, and illustrates a state in which the spool is neutral.

10 is a diagram showing the position of the pressure oil discharge part when the pressure of the pilot pressure oil is changed.

11 is a diagram showing a prior art.

12 is a diagram showing a prior art.

(Explanation of symbols for the main parts of the drawing)

3…. Flow direction control valve 4. spool

315, 316... Pilot ports 31e, 32e, 343... Pilot pressure oil pipe

344. Pilot pressure oil discharge port

So the first invention,

In the valve body 30, two pilot ports 315 and 316 and a spool 4 housed therein are provided.

A low pressure pilot pressure oil and a low pressure pilot pressure oil generated by supplying a low pressure pilot pressure oil to one of the two pilot ports 315 and 316 and supplying a high pressure pilot pressure oil to the other pilot port. In the flow direction control valve which moves the said spool 4 by a pressure difference, and changes the flow volume and direction of pressure oil according to the moving position of the said spool,

The valve body 30 is provided with a pilot pressure oil discharge port 344 for discharging high pressure pilot pressure oil,

As the spool 4 moves, the pilot port supplied with the high pressure pilot pressure oil and the pilot pressure oil discharge port 344 communicate with each other, and the pilot port supplied with the low pressure pilot pressure oil and the pilot pressure oil discharge port 344. It is characterized by blocking the communication of).

In addition, the second invention, in the first invention

And a conduit 343 along the longitudinal direction of the spool 4,

The pipeline 343 communicates with the pilot pressure oil discharge port 344 at any position of the pipeline 343,

The high pressure pilot pressure oil communicates the advanced pilot port to the conduit 343 as the spool 4 moves, and cuts off the communication between the pilot port supplied with the low pressure pilot pressure oil and the conduit 343. It is characterized by.

The first and second inventions will be described with reference to FIGS. 1, 2, 4, and 5.

The pilot pressure oils P1 and P2 are supplied from the control device 1 to the flow direction control valve 3. The pilot pressure oil P1 is supplied to one end of the spool 4 through the internal passage 325a of the switching piston 325 and the internal passage 323a of the retainer 323. The pilot pressure oil P2 is supplied to the other end side of the spool 4 through the internal passage 326a of the switching piston 326 and the internal passage 324a of the retainer 324. When the pressure of the pilot pressure oil P1 is smaller than the pressure of the pilot pressure oil P2, the elastic support force of the spring 322 and the elastic support force of the spring 328, and the pressure of the pilot pressure oil P2 is lower than that of the pilot pressure oil P1. When the pressure and the elastic bearing force of the spring 321 and the elastic bearing force of the spring 327 are smaller than that, that is, when the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is smaller than the predetermined value, the spool 4 is in the intermediate position. Is in.

When the lever 1a is in the middle position shown in FIG. 1, the spool 4 is in the middle position shown in FIG. Communication between the oil pressure supply unit 301 and the conduit 302 is blocked, and communication between the oil pressure supply unit 307 and the conduit 308 is blocked. On the other hand, the switching piston 305 is in the position where the pressure oil discharge part 325b communicates with the space | gap part 31d. Therefore, the pilot port 315 and the pilot pressure oil discharge port 344 have the internal flow path 325a, the pressure oil discharge part 325b, the air gap part 31d, and the pilot pressure oil pipe 31e of the switching piston 325. And a pilot pressure oil conduit 343. The switching piston 326 is at a position where the pressure oil discharge portion 326b communicates with the gap portion 32d. Therefore, the pilot port 316 and the pilot pressure oil discharge port 344 have an internal flow path 326a, a pressure oil discharge part 326b, a gap 32d, and a pilot pressure oil pipe 32e of the switching piston 326. And a pilot pressure oil conduit 343.

Therefore, the low pressure hydraulic oil is supplied from the pilot pressure oil discharge port 344 to the arm control unit 15 through the conduit 10. From this, the piston 12 of the arm control part 15 is located in the full stroke position 12a, and the hydraulic oil supplied to an arm becomes the maximum.

When the lever 1a is tilted in the direction of the arrow A shown in FIG. 1, the pressure of the pilot pressure oil P1 is less than the pressure of the pilot pressure oil P1, the elastic support force of the spring 321, and the elastic support force of the spring 327. It becomes large and the spool 4 moves to a figure left direction from an intermediate position. The state which the spool 4 moved is shown in FIG. The oil pressure supply part 301 and the direction control port 304 communicate with each other through the cutout part 41 and the conduit 302. The pressure oil supplied from the hydraulic pump to the pressure oil supply unit 301 is discharged from the direction control port 304 and supplied to the hydraulic motor.

By the movement of the spool 4, the retainer 323 and the switching piston 325 move in the leftward direction of the drawing. The communication between the pressure oil discharge part 325b of the lower surface switching piston 325 and the air gap 31d is blocked. On the other hand, the retainer 324 does not move while being in contact with the valve body 30, and the switching piston 326 does not move either. For this reason, the state where the pressure oil discharge part 326b and the space | gap part 32d of the switching piston 326 communicated is maintained. Therefore, the pilot pressure oil P2 is used for the pilot port 316, the internal flow path 326a of the switching piston 326, the pressure oil discharge part 326b, the air gap 32d, the pilot pressure oil pipe 32e, and the pilot pressure oil. The conduit 343 and the pilot pressure oil discharge port 344 are discharged to the conduit 10.

When the lever 1a is tilted in the direction of the arrow B shown in FIG. 1, the pressure of the pilot pressure oil P1 is less than the pressure of the pilot pressure oil P2, the elastic support force of the spring 322, and the elastic support force of the spring 328. It becomes large and the spool 4 moves to a right direction from a middle position. The state which the spool 4 moved is shown in FIG. The pressure oil supply part 307 and the direction control port 310 communicate with each other through the cutout part 43 and the conduit 308. The pressure oil supplied from the hydraulic pump to the pressure oil supply unit 307 is discharged from the direction control port 310 and is supplied to the hydraulic motor.

By the movement of the spool 4, the retainer 324 and the switching piston 326 and the drawing move in the right direction. The communication between the pressure oil discharge part 326b of the lower surface switching piston 326 and the space | gap part 32d is interrupted | blocked. On the other hand, the retainer 323 does not move while being in contact with the valve body 30, and the switching piston 325 does not move either. For this reason, the state where the pressure oil discharge part 325b and the space | gap part 31d of the switching piston 325 communicated is maintained. Therefore, the pilot pressure oil P1 is used for the pilot port 315, the internal flow path 325a of the switching piston 325, the hydraulic discharge part 325b, the air gap 31d, the pilot pressure oil pipe 31e, and the pilot pressure oil. The conduit 343 and the pilot pressure oil discharge port 344 are discharged to the conduit 10.

Therefore, the oil pressure of the high pressure side is supplied to the arm control part 15. FIG. The piston 12 of the arm control unit 15 is located at the stroke restraint position 12b, and the movement of the arm is limited.

Further, the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is controlled by the inclination movement amount of the lever 1a, and the movement position of the spool 4 is controlled. The flow rate of the pressure oil discharged from the direction control port 304 or the direction control port 310 is limited.

By operating the lever 1a provided in the control device 1, the traveling speed and the traveling direction of the work vehicle can be controlled.

According to the first invention, the high pressure pilot pressure oil is discharged from the pilot pressure oil discharge port 344 according to the movement of the spool 4 which controls the flow rate and direction of the pressure oil. In other words, the flow direction control valve 3 has a function of a shuttle valve. Therefore, since the shuttle valve is not used, the control device 1 becomes small and there is no need for a space for storing the shuttle valve in the cab. It also eliminates the need for a pipeline between the PPC valve and the shuttle valve.

According to the second invention, the pilot pressure oil discharge port 344 for discharging high-pressure pilot pressure oil is provided at an arbitrary position of the pilot pressure oil pipe 343 provided between the two pilot ports 315 and 316. It is possible. For this reason, the pilot pressure oil discharge port 344 is provided on the pilot pressure oil pipeline 343 by providing the pilot pressure oil discharge port 344 at the portion closest to the port of the hydraulic chamber 11 of the arm control unit 15. The port of the hydraulic chamber 11 can be communicated with a minimum pipe line.

As a result, the space in the cab becomes large, and the structure of the hydraulic circuit is simplified.

In addition, the third invention, in the first invention,

When the spool 4 moves to a specific position, the pilot port supplied with the high pressure pilot pressure oil and the pilot pressure oil discharge port 344 communicate with each other, and the pilot port supplied with the low pressure pilot pressure oil and the pilot pressure oil discharged. It is characterized in that the communication of the port 344 is blocked.

The third invention will be described with reference to FIGS. 1, 9 and 10. In FIG. 1, the flow direction control valve 500 is used in place of the flow direction control valve 3.

The pressure difference between the movement amount of the spool and the pilot pressure oils P1 and P2 is proportional. For example, it is assumed that the pressure of the pilot pressure oil P1 is P1a, P1b, P1c, P1d, and the pressure of the pilot pressure oil P2 is (P2a). 10 shows the position of the pressure oil discharge part in the case where the pressure of the pilot pressure oil P1 is P1a, P1b, P1c, and P1d.

When the pressure of the pilot pressure oil P1 is P1a, the pressure oil discharge part 47 is in the position 47a, and the communication between the hydraulic discharge part 47 and the space | gap part 505 is interrupted | blocked.

When the pressure of the pilot pressure oil P1 is P1b, the pressure oil discharge part 47 is at the position 47b, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

When the pressure of the pilot pressure oil P1 is P1c, the pressure oil discharge part 47 is at the position 47c, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

When the pressure of the pilot pressure oil P1 is P1d, the pressure oil discharge part 47 is in the position 47d, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

As shown in FIG. 10, when the pressure of pilot pressure oil P1 is in P1b-P1c, pilot pressure oil P1 is a pilot port 315, the internal flow path 45 of the spool 4, the hydraulic discharge part ( 47), the air gap 505, the pilot pressure oil conduit 503, and the pilot pressure oil discharge port 344 is discharged to the conduit 10.

According to the third invention, the high pressure pilot pressure oil is discharged in accordance with the movement amount of the spool 4 which controls the flow rate and direction of the pressure oil. Since the movement amount of the spool 4 and the pressure difference between the pilot pressure oils P1 and P2 are proportional to each other, when the pressure of the low pressure pilot pressure oil is made constant, the movement amount of the spool 4 is determined by the pressure of the high pressure pilot pressure oil. Therefore, when the pressure of the high pressure pilot pressure oil is at a predetermined pressure, the pressure discharge parts 47 and 48 and the air gaps 505 and 506 of the spool 4 are communicated with each other to discharge the pilot pressure oil at the predetermined pressure. For this reason, in order to detect a predetermined pressure, it is unnecessary to provide a separate pressure sensor.

As a result, the space in the cab becomes large, and the structure of the hydraulic circuit is simplified.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the pressure oil supply apparatus which concerns on this invention is described with reference to drawings.

In the following embodiment, it is assumed that the hydraulic motor which operates the traveling body of a work vehicle as a hydraulic actuator is assumed, and the operation | movement of the arm provided in the work vehicle is restrict | limited using high pressure pilot pressure oil.

EMBODIMENT OF THE INVENTION The 1st Embodiment of this invention is described with reference to FIGS.

1 is a configuration diagram of an embodiment of the present invention. 2 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is neutral. 3 is an enlarged cross-sectional structure diagram of a cover portion of a flow direction control valve.

In this embodiment, left and right traveling bodies are provided in the work vehicle, and hydraulic motors are provided in each traveling body. Each hydraulic motor operates with hydraulic oil supplied from the hydraulic pump. At this time, when the lever 1a of the control apparatus 1 is operated, the spool 4 of the flow direction control valve 3 moves, and the flow volume and direction of the hydraulic oil supplied to a hydraulic motor are controlled. On the other hand, the work vehicle is equipped with an arm. When the lever 1a is operated, since the piston 12 moves to the stroke restraint position 12b and the movement position of the arm spool 13 is limited, the operation of the arm is limited.

The control device 1 shown in FIG. 1 is provided in the cab of the work vehicle. The control device 1 communicates with the flow direction control valve 3 by way of the conduits 5 and 6. In addition, the flow direction control valve 3 communicates with the hydraulic pressure chamber 11 of the female control part 15 by the pipeline 10.

The control device 1 is provided with a lever 1a and a PPC valve 1b. When the lever 1a is inclinedly moved, the pilot pressure oil according to the inclined movement amount is discharged from the PPC valve 1b.

As shown in FIG. 2, the flow direction control valve 3 is composed of a valve body 30 and a spool 4.

Inside the valve body 30, a spool sliding hole 33, pressure oil supply parts 301 and 307, pipe lines 302 and 308, and a pilot pressure oil pipe 343 are provided. Outside of the valve body 30, the pilot control oil communicated to the direction control port 304 in communication with the conduit 302, the direction control port 310 in communication with the conduit 308, and the pilot pressure oil conduit 343. The discharge port 344 and the covers 31 and 32 are provided.

The spool 4 is provided in the spool sliding hole 33 so as to be slidable in the longitudinal direction thereof. Cutouts 41 and 43 are provided on the sliding surface of the spool 4.

As shown in Fig. 3, the cover 31 has a spring chamber 31a, a spring chamber 31b, a switching piston sliding hole 31c which communicates with the spring chamber 31a and the spring chamber 31b. The air gap portion 31d and the pilot pressure oil conduit 31e are provided.

The spring 321 and the retainer 323 are provided in the spring chamber 31a. The retainer 323 is pressed against the spool 4 side by the spring 321 and contacts the spool 4 or the valve body 30, or the spool 4 and the valve body 30. The retainer 323 is such that its central axis and the central axis of the spool 4 are located on the same straight line. In addition, the retainer 323 is provided with an internal flow passage 323a penetrating the sliding direction.

A spring 327 is provided in the spring chamber 31b.

A switching piston 325 is slidably installed in the switching piston sliding hole 31c. One end of the switching piston 325 is in the spring chamber 31a, and the other end of the switching piston 325 is in the spring chamber 31b. The switching piston 325 is pressed against the retainer 323 side by the spring 327 and is in contact with the retainer 323. In addition, the switching piston 325 has its center axis and the center axis of the spool 4 located on the same straight line. The switching piston 325 is provided with an internal flow passage 325a penetrating in the sliding direction and a pressure oil discharge portion 325b penetrating from the sliding surface to the internal flow passage 325a.

A part of the sliding surface of the switching piston sliding hole 31c is provided with a gap 31d. The void portion 31d is in communication with the pilot pressure oil conduit 31e. In addition, the pilot pressure oil conduit 31e communicates with the pilot pressure oil conduit 343 of the valve body 30.

In addition, a pilot port 315 is provided outside the cover 31.

Since the structure of the cover 32 is also the same as that of the cover 31, the description is abbreviate | omitted here.

As shown in FIG. 1, the pilot pressure oil conduit 343 of the flow direction control valve 3 and the hydraulic pressure chamber 11 of the arm control unit 15 communicate with each other via the conduit 10.

The arm control unit 15 includes a hydraulic chamber 11, a piston 12, and an arm spool 14. When the piston 12 is in the full stroke position 12a, the arm spool 13 can move to the full stroke position 12a. In this case, the flow rate of the pressurized oil supplied from the hydraulic motor to the arm becomes maximum. On the other hand, when the piston 12 is in the stroke restraint position 12b, the arm spool 13 can only move to the stroke restraint position 12b. As a result, the maximum amount of pressure oil is not supplied to the arm.

Next, the flow direction control valve 3 will be described with reference to FIGS. 1, 2, 4, and 5.

4 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the left direction of the drawing. 5 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the right direction of the drawing.

The pilot pressure oils P1 and P2 are supplied from the control device 1 to the flow direction control valve 3. The pilot pressure oil P1 is supplied to one end of the spool 4 through the internal passage 325a of the switching piston 325 and the internal passage 323a of the retainer 323. The pilot pressure oil P2 is supplied to the other end side of the spool 4 through the internal passage 326a of the switching piston 326 and the internal passage 324a of the retainer 324. When the pressure of the pilot pressure oil P1 is smaller than the pressure of the pilot pressure oil P2, the elastic support force of the spring 322 and the elastic support force of the spring 328, and the pressure of the pilot pressure oil P2 is lower than that of the pilot pressure oil P1. When the pressure and the elastic bearing force of the spring 321 and the elastic bearing force of the spring 327 are smaller than that, that is, when the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is smaller than the predetermined value, the spool 4 is in the intermediate position. Is in.

When the lever 1a is in the middle position shown in FIG. 1, the spool 4 is in the middle position shown in FIG. Communication between the pressure oil supply unit 301 and the conduit 302 is blocked, and communication between the pressure oil supply unit 307 and the conduit 308 is blocked. On the other hand, the switching piston 325 is in the position where the pressure oil discharge part 325b communicates with the space | gap part 31d. Therefore, the pilot port 315 and the pilot pressure oil discharge port 344 have the internal flow path 325a, the pressure oil discharge part 325b, the air gap part 31d, and the pilot pressure oil pipe 31e of the switching piston 325. And a pilot pressure oil conduit 343. The switching piston 326 is at a position where the pressure oil discharge portion 326b communicates with the gap portion 32d. Therefore, the pilot port 316 and the pilot pressure oil discharge port 344 have the internal flow path 326a, the pressure oil discharge part 326b, the air gap 32d, and the pilot pressure oil pipe 32e of the switching piston 326. And a pilot pressure oil conduit 343.

Therefore, low pressure pressure oil is supplied from the pilot pressure oil discharge port 344 to the arm control unit 15 through the conduit 10. From this, the piston 12 of the arm control part 15 is located in the full stroke position 12a, and the hydraulic oil supplied to an arm becomes the maximum.

When the lever 1a is tilted in the direction of the arrow A shown in FIG. 1, the pressure of the pilot pressure oil P2 is less than the pressure of the pilot pressure oil P1, the elastic support force of the spring 321, and the elastic support force of the spring 327. It becomes large and the spool 4 moves to a figure left direction from an intermediate position. The state which the spool 4 moved is shown in FIG. The oil pressure supply part 301 and the direction control port 304 communicate with each other through the cutout part 41 and the conduit 302. The pressure oil supplied from the hydraulic pump to the pressure oil supply unit 301 is discharged from the direction control port 304 and supplied to the hydraulic motor.

By the movement of the spool 4, the retainer 323 and the switching piston 325 move in the leftward direction of the drawing. The communication between the pressure oil discharge part 325b of the lower surface switching piston 325 and the air gap 31d is blocked. On the other hand, the retainer 324 does not move while being in contact with the valve body 30, and the switching piston 326 does not move either. For this reason, the state where the pressure oil discharge part 326b and the space | gap part 32d of the switching piston 326 communicated is maintained. Therefore, the pilot pressure oil P2 is used for the pilot port 316, the internal flow path 326a of the switching piston 326, the pressure oil discharge part 326b, the air gap 32d, the pilot pressure oil pipe 32e, and the pilot pressure oil. The conduit 343 and the pilot pressure oil discharge port 344 are discharged to the conduit 10.

When the lever 1a is tilted in the direction of the arrow B shown in FIG. 1, the pressure of the pilot pressure oil P1 is less than the pressure of the pilot pressure oil P2, the elastic support force of the spring 322, and the elastic support force of the spring 328. It becomes large and the spool 4 moves to a right direction from a middle position. The state which the spool 4 moved is shown in FIG. The pressure oil supply part 307 and the direction control port 310 communicate with each other through the cutout part 43 and the conduit 308. The pressure oil supplied from the hydraulic pump to the pressure oil supply unit 307 is discharged from the direction control port 310 and is supplied to the hydraulic motor.

By the movement of the spool 4, the retainer 324 and the switching piston 326 move in the right direction in the drawing. The communication between the pressure oil discharge part 326b of the switching surface piston 326 and the space | gap part 32d is interrupted | blocked. On the other hand, the retainer 323 does not move while being in contact with the valve body 30, and the switching piston 325 does not move either. For this reason, the state where the pressure oil discharge part 325b and the space | gap part 31d of the switching piston 325 communicated is maintained. Therefore, the pilot pressure oil P1 is used for the pilot port 315, the internal passage 325a of the switching piston 325, the pressure oil discharge part 325b, the air gap 31d, the pilot pressure oil pipe 31e, and the pilot pressure oil. The conduit 343 and the pilot pressure oil discharge port 344 are discharged to the conduit 10.

Therefore, the oil pressure of the high pressure side is supplied to the arm control part 15. FIG. From this, the piston 12 of the arm control part 15 is located in the stroke restricting position 12b, and movement of an arm is restrict | limited.

Further, the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is controlled by the inclination movement amount of the lever 1a, and the movement position of the spool 4 is controlled. Lower flow rates of the pressurized oil discharged from the direction control port 304 and the direction control port 310 are limited.

By operating the lever 1a provided in the controller 1, the traveling speed and the traveling direction of the work vehicle can be controlled.

In the first embodiment, the pilot pressure oils P1 and P2 are discharged through the switching pistons 325 and 326 moving in accordance with the movement of the spool 4.

Next, the flow direction direction control valve of embodiment other than 1st embodiment is demonstrated.

In the second embodiment described below, the pilot pressure oil is not discharged through the switching piston, but the pilot pressure oil is discharged through the spool.

6 is a cross-sectional structural view of the flow direction control valve, showing a state where the spool is in the middle position. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

The flow direction control valve 500 largely consists of the valve body 50 and the spool 4.

Inside the valve body 50, the spool sliding hole 33, the hydraulic oil supply parts 301, 307, the air gaps 501, 502, the conduits 302, 308, and the air gaps 501, 502. A pilot pressure oil conduit 503 is provided in communication therewith. Outside the valve body 30, the direction control port 304 communicated with the conduit 302, the direction control port 310 communicated with the conduit 308, and the pilot pressure oil communicated with the pilot pressure conduit 503 The discharge port 344 and the covers 51 and 52 are provided.

When the pilot pressure oil P1 becomes higher than the pilot pressure oil P2 and the spool 4 moves (in the right direction in the drawing), the air gap portion 501 is the oil pressure discharge portion 47 of the spool 4 described later. And the pilot pressure oil P1 are lower than the pilot pressure oil P2 and the spool 4 moves (leftward in the drawing), the air gap 501 discharges the pressure oil of the spool 4 described later. Communication with the unit 47 is blocked.

When the pilot pressure oil P2 becomes higher than the pilot pressure oil P1 and the spool 4 moves (leftward in the drawing), the air gap portion 502 is the pressure oil discharge portion 48 of the spool 4 described later. And the pilot pressure oil P2 are lower than the pilot pressure oil P1 and the spool 4 moves (in the right direction in the drawing), the air gap 502 discharges the pressure oil of the spool 4 described later. Communication with the part 48 is blocked.

The spool 4 is provided in the spool sliding hole 33 so as to be slidable in the longitudinal direction thereof. Cutouts 41 and 43 are provided on the sliding surface of the spool 4. One end of the spool 4 is provided with an internal flow passage 45 and a pressure oil discharge portion 47 penetrating from the sliding surface of the spool 4 to the internal flow passage 45. The other end of the spool 4 is provided with an internal flow passage 46 and a pressure oil discharge portion 48 penetrating from the sliding surface of the spool 4 to the internal flow passage 46.

A spring chamber 51a is provided inside the cover 51.

A spring 321 and a retainer 323 are provided in the spring chamber 51a. The retainer 323 is pressed against the spool 4 side by the spring 321 and contacts the spool 4 or the valve body 30, or the spool 4 and the valve body 30. The retainer 323 is such that its central axis and the central axis of the spool 4 are located on the same straight line. In addition, the retainer 323 is provided with an internal flow passage 323a penetrating in the sliding direction.

In addition, a pilot port 315 is provided outside the cover 51.

Since the structure of the cover 52 is the same as that of the cover 51, the description is abbreviate | omitted here.

Next, the operation of the flow direction control valve 500 will be described with reference to FIGS. 1 and 6 to 8. In FIG. 1, the flow direction control valve 500 is used in place of the flow direction control valve 3.

7 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the left direction in the drawing. 8 is a cross-sectional structural view of the flow direction control valve, and shows a state in which the spool is in the right direction in the drawing.

Since the flow of the pressurized oil to a hydraulic motor is the same as that of the flow direction control valve 3 of 1st Embodiment, the description is abbreviate | omitted.

Pilot pressure oils P1 and P2 are supplied to the flow direction control valve 500 from the control apparatus 1. The pilot pressure oil P1 passes through the internal passage 323a of the retainer 323 and is supplied to one end of the spool 4. The pilot pressure oil P2 passes through the internal passage 324a of the retainer 324 and is supplied to the other end of the spool 4. When the pressure of the pilot pressure oil P1 is smaller than the pressure of the pilot pressure oil P2 and the elastic bearing force of the spring 322, and the pressure of the pilot pressure oil P2 is the pressure of the pilot pressure oil P1 and the elasticity of the spring 321. When the pressure is smaller than the bearing force, that is, when the pressure difference between the pilot pressure oil P1 and the pilot pressure oil P2 is smaller than the predetermined value, the spool 4 is in the middle position.

When the lever 1a is in the middle position shown in FIG. 1, since the spool 4 is in the middle position shown in FIG. 6, the pressure oil discharge part 47 communicates with the air gap 501, and the pressure oil discharge part ( 48 is in communication with the void 502. Therefore, the pilot port 315 and the pilot pressure oil discharge port 344 connect the internal passage 45, the pressure oil discharge part 47, the air gap 501, and the pilot pressure oil pipe 503 of the spool 4. And a pilot port 316, a pilot pressure oil discharge port 344, an internal flow path 46 of the spool 4, a pressure oil discharge part 48, a cavity 502, and a pilot pressure oil pipe 503. It is communicated through.

Therefore, low pressure pressure oil is supplied from the pilot pressure oil discharge port 344 to the arm control unit 15 through the conduit 10. The piston 12 of the arm control part 15 is located in the full stroke position 12a rather than this, and the pressure oil supplied to an arm becomes maximum.

When the lever 1a is tilted in the direction of the arrow A shown in Fig. 1, the pressure of the pilot pressure oil P2 is greater than the pressure of the pilot pressure oil P1 and the elastic bearing force of the spring 321, and the spool 4 It moves to the left in the drawing from the median position. The state which the spool 4 moved is shown in FIG.

By the movement of the spool 4, the communication between the hydraulic oil discharge part 47 and the space | gap part 501 is interrupted | blocked. On the other hand, when the spool 4 moves to the left in the drawing, the state in which the hydraulic oil discharge part 48 and the air gap 502 communicate with each other is maintained. Therefore, the pilot pressure oil P2 includes the pilot port 316, the internal flow path 324a of the retainer 324, the internal flow path 46 of the spool 4, the pressure oil discharge part 48, the air gap 502, and the pilot. The pressure oil pipe 503 and the pilot pressure oil discharge port 344 are discharged to the pipe line 10.

When the lever 1a is tilted in the direction of the arrow B shown in Fig. 1, the pressure of the pilot pressure oil P1 is greater than the pressure of the pilot pressure oil P2 and the elastic bearing force of the spring 322, and the spool 4 Move in the right direction from the middle position. 8 shows a state in which the spool 4 is moved.

The movement of the hydraulic oil discharge part 48 and the space | gap part 502 is interrupted by the movement of the spool 4. On the other hand, when the spool 4 moves in the right direction in the drawing, the state in which the hydraulic oil discharge part 47 and the gap 501 communicate with each other is maintained. Therefore, the pilot pressure oil P1 includes the pilot port 315, the internal flow path 323a of the retainer 323, the internal flow path 45 of the spool 4, the pressure oil discharge part 47, the air gap 501, The pilot pressure oil pipeline 503 and the pilot pressure oil discharge port 344 are discharged to the pipeline 10.

Therefore, the oil pressure of the high pressure side is supplied to the arm control part 15. FIG. The piston 12 of the arm control unit 15 is located at the stroke restraint position 12b, and the movement of the arm is limited.

By operating the lever 1a provided in the control device 1, the traveling speed and the traveling direction of the work vehicle can be controlled.

In the first and second embodiments, the high pressure pilot pressure oil is discharged from the pilot pressure oil discharge port 344 according to the movement of the spool 4 for controlling the flow rate and direction of the pressure oil. In short, the flow direction control valve 3 has a function of a shuttle valve. Therefore, since the shuttle valve is not used, the control device 1 becomes small and there is no need for a space for storing the shuttle valve in the cab. In addition, there is no need for piping between the PPC valve and the shuttle valve.

In addition, the pilot pressure oil discharge port 344 for discharging the high-pressure pilot pressure oil can be provided at any position of the pilot pressure oil pipe 343 provided between the two pilot ports 315 and 316. For this reason, the pilot pressure oil discharge port 344 and the pressure chamber are provided on the pilot pressure oil pipeline 343 by providing the pilot pressure oil discharge port 344 in the closest portion of the pressure chamber 11 of the arm control unit 15. The port of (11) can be communicated with the minimum piping.

As a result, the space in the cab becomes large, and the structure of the hydraulic circuit is simplified.

In the first and second embodiments, one of the high pressure pilot pressure oils of the pilot oil pressures P1 and P2 is discharged from the pilot pressure oil discharge port 344. However, it is also possible to allow only pilot pressure oil within a predetermined pressure range to be discharged from the pilot pressure oil discharge port 344.

Next, the flow direction control valve of 3rd Embodiment is demonstrated.

In the embodiment shown below, only the pilot pressure oil within a predetermined pressure range is discharged from the pilot pressure oil discharge port 344.

9 is a cross-sectional structural view of the flow direction control valve, illustrating a state in which the spool is in the middle position. Fig. 10 is a diagram showing the position of the pressure oil discharge portion when the pressure of the pilot pressure oil is changed. Hereinafter, the same code | symbol is attached | subjected to the same component as embodiment shown in FIG. 2, FIG. 6, and description is abbreviate | omitted suitably.

In the valve body 500, when the pilot pressure oil P1 is higher than the pilot pressure oil P2 and the pressure difference between the pilot pressure oils P1 and P2 is within a predetermined range, the air gap communicates with the pressure oil discharge part 47. The part 505 and the space | gap part which communicates with the pressure oil discharge part 48, when the pilot pressure oil P2 is higher than the pilot pressure oil P1, and the pressure difference of pilot pressure oils P1 and P2 are in a predetermined range. 506 is provided.

The amount of movement of the spool is proportional to the pressure difference between the pilot pressure oils P1 and P2. For example, it is assumed that the pressure of the pilot pressure oil P1 is P1a, P1b, P1c, P1d, and the pressure of the pilot pressure oil P2 is P2a. 10 shows the position of the pressure discharge part in the case where the pressure of the pilot pressure oil P1 is P1a, P1b, P1c, and P1d.

When the pressure of the pilot pressure oil P1 is P1a, the pressure oil discharge part 47 is in the position 47a, and the communication between the hydraulic discharge part 47 and the space | gap part 505 is interrupted | blocked.

When the pressure of the pilot pressure oil P1 is P1b, the pressure oil discharge part 47 is at the position 47b, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

When the pressure of the pilot pressure oil P1 is P1c, the pressure oil discharge part 47 is at the position 47c, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

When the pressure of the pilot pressure oil P1 is P1d, the pressure oil discharge part 47 is in the position 47d, and the communication between the hydraulic discharge part 47 and the air gap 505 is blocked.

As shown in Fig. 10, when the pressure of the pilot pressure oil P1 is in P1b to P1c, the pilot pressure oil P1 includes the pilot port 315, the internal flow path 45 of the spool 4, and the pressure oil discharge part ( 47), the air gap 505, the pilot pressure oil conduit 503, and the pilot pressure oil discharge port 344 is discharged to the conduit 10.

The same applies to the case where the pilot pressure oil P2 is higher than the pilot pressure oil P1.

In the third embodiment, the high pressure pilot pressure oil is discharged in accordance with the movement amount of the spool 4 which controls the flow rate and direction of the pressure oil. Since the movement amount of the spool 4 is proportional to the pressure difference between the pilot pressure oils P1 and P2, when the pressure of the low pressure pilot pressure oil is made constant, the movement amount of the spool 4 is determined by the pressure of the high pressure pilot pressure oil. All. Therefore, when the pressure of the high pressure pilot pressure oil is at the predetermined pressure, the pressure oil discharge parts 47 and 48 of the spool 4 communicate with the air gaps 505 and 506, respectively, so that the pilot pressure oil of the predetermined pressure can be discharged. For this reason, in order to detect a predetermined pressure, it is unnecessary to provide a separate pressure sensor.

As a result, the space in the cab becomes large, and the structure of the hydraulic circuit is simplified.

In addition, in the above embodiment, the present invention, which assumes a hydraulic motor of a work vehicle as the hydraulic actuator, is not limited to this, and also restricts the operation of other hydraulic actuators as well as to restrict the operation of the arm of high pressure pilot pressure oil. It may be used in order to.

The flow direction control valve of the present invention can discharge the high pressure pilot pressure oil without using a shuttle valve or a pressure sensor, thereby making the space in the cab large and simplifying the construction of the hydraulic circuit.

Claims (3)

In the valve body 30, two pilot ports 315 and 316 and a spool 4 housed therein are provided. A low pressure pilot pressure oil and a low pressure pilot pressure oil generated by supplying a low pressure pilot pressure oil to one of the two pilot ports 315 and 316 and supplying a high pressure pilot pressure oil to the other pilot port. In the flow direction control valve which moves the said spool 4 by a pressure difference, and changes the flow volume and direction of pressure oil according to the moving position of the said spool, The valve body 30 is provided with a pilot pressure oil discharge port 344 for discharging high pressure pilot pressure oil, As the spool 4 moves, the pilot port supplied with the high pressure pilot pressure oil and the pilot pressure oil discharge port 344 communicate with each other, and the pilot port supplied with the low pressure pilot pressure oil and the pilot pressure oil discharge port 344. Flow direction control valve, characterized in that to block communication. A pipe 343 along the longitudinal direction of the spool 4, The pipeline 343 communicates with the pilot pressure oil discharge port 344 at any position of the pipeline 343, In accordance with the movement of the spool 4, the pilot port of the high pressure pilot pressure oil is communicated to the conduit 343, and the communication between the pilot port supplied with the low pressure pilot pressure oil and the conduit 343 Flow direction control valve, characterized in that. 2. The pilot according to claim 1, wherein the pilot port supplied with the high pressure pilot pressure oil and the pilot pressure oil discharge port 344 communicate with each other when the spool 4 moves to a specific position. Flow direction control valve characterized in that the communication between the port and the pilot pressure oil discharge port (344) is blocked.