JP2007307959A - Hydraulic system for industrial vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently supply hydraulic oil into each of a steering actuator and the other actuator, and to simultaneously and finely supply the hydraulic oil into both actuators. <P>SOLUTION: An solenoid valve connected to the steering actuator and the other actuator by hydraulic piping is provided between a priority valve and a pump. The solenoid valve can be switched among a first state permitting a flow of the hydraulic oil from the pump to the priority valve preventing the flow of each actuator, a second state preventing the flow of the hydraulic oil from the pump to the priority valve and permitting a flow to the steering actuator, and a third state preventing the flow from the pump to the priority valve and permitting a flow of the hydraulic oil to the other actuator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic system for an industrial vehicle that operates a steering actuator by hydraulic pressure, and more particularly to a hydraulic system that can supply hydraulic oil from a pump that supplies hydraulic oil to a steering actuator to another hydraulic actuator.

  Conventionally, in a vehicle equipped with a hydraulic steering device, hydraulic oil is supplied to actuators of other hydraulic devices using a pump that supplies hydraulic oil to a steering actuator provided in the steering device, and the device is operated. In this way, the system is simplified and reduced in weight. For example, in the technique of Patent Document 1, hydraulic oil can be supplied from a steering pump to a power steering system, an elevator, and a vehicle height adjustment system, and the switching valve is switched according to the operation and supplied to either. ing. In the technique of Patent Document 2, hydraulic oil can be supplied from a steering pump to a steering cylinder and a working actuator, and a pilot pressure operation type switching valve is switched and supplied to any one of them. Yes.

JP 10-44739 A JP 2000-85598 A

  Now, when switching between supplying the hydraulic oil from the pump to the steering actuator or other actuators with a switching valve such as a priority valve, when trying to supply hydraulic oil to both actuators simultaneously, The switching valve is frequently switched. For this reason, there is a problem that the efficiency is deteriorated and a shock occurs at the time of switching. However, simply supplying a sufficient amount of hydraulic fluid to both actuators eliminates the shock caused by switching, but if the actuator is not operated, the hydraulic fluid is returned to the tank as it is. Not right.

  An object of the present invention is to be able to supply hydraulic oil to a steering actuator and other actuators simultaneously and satisfactorily and to supply hydraulic oil to each actuator efficiently.

  In order to achieve the above object, the present invention is an industrial vehicle hydraulic system in which hydraulic oil is supplied to other actuators by a pump that supplies hydraulic oil to a steering actuator that operates in response to a steering operation. A priority valve that is connected to the steering actuator and the other actuator by hydraulic piping, and can be switched to a state that allows the flow of hydraulic oil from the pump to any one of the actuators, the priority valve, An electromagnetic valve provided between the pump and the steering actuator and the other actuator respectively connected by hydraulic piping, and a control device for controlling the electromagnetic valve, the electromagnetic valve from the pump to the pump Allow the flow of hydraulic oil to the priority valve and A first state in which the flow to the first valve is blocked, a second state in which the flow of hydraulic oil from the pump to the priority valve is blocked and a flow to the steering actuator is permitted, and a flow from the pump to the priority valve. Is configured to be capable of switching to a third state in which the flow of hydraulic oil to the other actuators is allowed.

  According to the present invention, when supplying hydraulic oil to both actuators, both actuators can be operated simultaneously by switching the priority valve after switching the electromagnetic valve to the first state. Also, for example, when supplying hydraulic oil only to the steering actuator, it can be switched to the second state, and when supplying hydraulic oil only to the other actuators, it can be switched to the third state. In the second state and the third state, hydraulic fluid can be supplied to the steering actuator or another actuator without passing through the priority valve and without switching the priority valve.

  In the above configuration, in the second state, the electromagnetic valve blocks the flow of hydraulic oil from the pump to the priority valve, and mainly allows the flow to the steering actuator. In the state 3, the flow of hydraulic oil from the pump to the priority valve is blocked, and the flow to the other actuators is mainly allowed.

  In this way, no hydraulic oil is supplied to the priority valve in the second state, but some hydraulic oil is supplied to other actuators, and then the other actuators operate through the priority valve. When supplying oil and when switching to the third state and supplying hydraulic oil to other actuators, it is possible to suppress the occurrence of shock due to sudden start of the hydraulic oil. Similarly, hydraulic oil is not supplied to the priority valve in the third state, but when hydraulic oil is supplied to the steering actuator somewhat, the hydraulic oil is then supplied to the steering actuator through the priority valve. And when switching to the second state and supplying hydraulic oil to the steering actuator, it is possible to suppress the occurrence of a shock due to sudden start of the hydraulic oil flowing.

  If the amount of oil supplied to the other actuator in the second state is too large, the operation of the steering actuator is affected. If the amount of oil supplied to the steering actuator in the third state is too large, the other actuator is affected. It is important not to supply more than necessary.

  In addition to the above-described configuration, in the case of including a driver detection unit that detects whether or not the driver is boarding the vehicle, the control device sets the electromagnetic valve to the third valve when the driver is not boarding. It can be controlled to switch to this state.

  In this way, when the driver is not on board, the electromagnetic valve can be switched to the third state, so that the hydraulic oil can be preferentially supplied to the other actuators, and can be passed through the priority valve. Hydraulic oil can be supplied efficiently.

  Further, in addition to the above configuration, in the case of including a handle detection means for detecting whether or not the handle is operated, the control device sets the electromagnetic valve to the third state when the handle is not operated. It can be controlled to switch.

  In this way, if the handle is not operated, the solenoid valve is switched to the third state, so that the hydraulic oil can be supplied preferentially to other actuators, and without passing through the priority valve. The hydraulic oil can be supplied efficiently.

  Furthermore, in addition to the above-described configuration, the control device includes an operation tool detection unit that detects whether or not the operation tool operated by the driver to operate the other actuator is operated. If not, the electromagnetic valve can be controlled to switch to the second state.

  In this way, if the operation tool is not operated, the hydraulic valve can be switched to the second state, so that the hydraulic oil can be preferentially supplied to the steering actuator, and the priority valve can be passed. Hydraulic oil can be supplied efficiently.

  In the above configuration, the control device may control the electromagnetic valve to be switched to the first state when the handle is operated and the operation tool is operated.

  In this way, if the handle is operated and the operation tool is operated, the electromagnetic valve is switched to the first state, so that all the hydraulic oil from the pump flows to the priority valve. At this time, by switching the priority valve, the working oil can be diverted and both actuators can be operated simultaneously.

  In the above configuration, in the case where the other actuator is a single-acting hydraulic cylinder that extends when hydraulic oil is supplied and recovers and shortens the hydraulic oil, the control device operates the handle. And when the operation tool is operated to supply hydraulic oil to the other actuator, the electromagnetic valve is controlled to be switched to the first state, and the operation tool is operated to the other actuator. When not operated to supply oil, the electromagnetic valve is controlled to switch to the second state, the handle is not operated, and the operating tool supplies hydraulic oil to the other actuator. In such a case, the electromagnetic valve can be controlled to be switched to the third state.

  In this way, when the handle is operated and the operating tool is operated so as to supply hydraulic oil to another actuator, the electromagnetic valve is switched to the first state. The hydraulic oil can be diverted and both actuators can be operated simultaneously. In addition, when the operation tool is not operated to supply hydraulic oil to another actuator, the electromagnetic valve is switched to the second state, so that the hydraulic oil can be supplied preferentially to the steering actuator. Furthermore, when the handle is not operated and the operating tool is operated to supply hydraulic fluid to another actuator, the electromagnetic valve is switched to the third state, so that the other actuator is given priority. Hydraulic oil can be supplied.

  Further, the number of other actuators in the present invention is not limited to one, and there may be a plurality of other actuators, and the application (device operated by the actuator) is not limited to one.

  As described above, according to the present invention, when supplying hydraulic oil to both actuators, the priority valve may be switched after the electromagnetic valve is switched to the first state. When supplying the hydraulic oil only to the actuator, the hydraulic oil can be supplied without passing through the priority valve by switching the electromagnetic valve to the second state or the third state.

  Hereinafter, an embodiment in which the present invention is applied to a forklift will be described with reference to the drawings.

  As shown in FIG. 1, the forklift according to this embodiment includes a front wheel 2 as a driving wheel at a front portion of a vehicle body 1, and a rear wheel 3 as a steered wheel at a rear portion of the vehicle body 1. The rear wheel 3 is attached to a steering device provided on the vehicle body 1, and the steering device is provided with a steering cylinder 4 that turns the rear wheel 3 to change its direction. Here, the steering cylinder 4 is a double-acting double rod cylinder, and the rear wheel 3 turns with the movement of the rod. Further, a battery 5 is mounted in the front and rear center of the vehicle body 1, and a seat 6 on which a driver sits is provided on a cover that covers the battery 5. The seat 6 is provided with a seat switch 6a that is turned on when the driver is seated and turned off when the driver leaves the seat.

A steering handle 7 for turning the rear wheel 3 so as to face the driver sitting on the seat 6, a lift lever 8 for raising and lowering a fork 11 described later, A tilt lever 9 for tilting 10 is provided.
The steering handle 7 is rotatably provided within a predetermined operation range, and the steering handle 7 is provided with a steering sensor 7a for detecting the operation torque. The lift lever 8 and the tilt lever 9 are both tiltable forward and backward. The lift lever 8 is provided with a lift switch 8a that is switched on / off according to the operation, and the tilt lever 9 is operated. A tilt switch 9a that is switched on / off according to the above is attached. Here, the lift switch 8a is turned on when the lift lever 8 is operated backward (frontward as viewed from the driver), and is operated forward (backward as viewed from the driver) and when it is not operated. It is provided to be off. The tilt switch 9a is turned on when the tilt lever 9 is operated forward (backward when viewed from the driver) or backward (frontward when viewed from the driver), and is turned off when the tilt lever 9 is not operated. .

  Further, as shown in FIG. 1, a mast 10 is supported at the front portion of the vehicle body 1 so as to be tiltable, and a fork 11 is supported on the mast 10 so as to be movable up and down. The mast 10 is provided with a lift cylinder 12 formed of a single-acting single rod cylinder. The fork 11 is raised when the lift cylinder 12 is extended, and is lowered when the lift cylinder 12 is shortened. A tilt cylinder 13 composed of a double-acting single rod cylinder is provided between the vehicle body 1 and the mast 10. When the tilt cylinder 13 extends, the mast 10 tilts forward together with the fork 11 and the lift cylinder 12, and the tilt cylinder 13. When it is shortened, it tilts backward.

  The vehicle body 1 is provided with a tank 14 that stores hydraulic oil to be supplied to each cylinder. Further, a pump 15 that pressurizes and discharges hydraulic oil sucked from the tank 14, and a motor 16 that drives the pump 15. Is provided. The motor 16 is provided with a motor sensor 16a for detecting the rotational speed.

  As shown in FIG. 2, the hydraulic oil from the pump 15 is supplied as it is to the electromagnetic valve 17, and supply paths X 1, Y 1, Z 1 are connected to the electromagnetic valve 17. The supply path X1 is connected to the priority valve 18, and the priority valves 18 are connected to supply paths Y2 and Z2. The priority valve 18 is adapted to obtain a pilot pressure from the supply path Y2, so that a control flow flows through the supply path Y2 and an excess flow flows through the supply path Z2. The supply paths Y1 and Y2 merge and are connected to the steering valve 19, and the hydraulic oil from the steering valve 19 is recovered to the tank 14 by the recovery path Y3. Further, the supply paths Z1 and Z2 are joined and connected to the lift valve 20 and the tilt valve 21, and the hydraulic oil from both valves is recovered to the tank 14 by the recovery path Z3.

  The electromagnetic valve 17 is electrically switchable in position, and as shown in FIG. 2, a first valve that allows the flow from the pump 15 to the supply path X1 and blocks the flow to the supply paths Y1 and Z1. Position (the center position in FIG. 2) and a second position (blocking the flow from the pump 15 to the supply path X1, allowing the flow to the supply path Y1, and allowing the restricted flow to the supply path Z1 ( The third position (FIG. 2 shows the position on the right side) and the flow from the pump 15 to the supply path X1, allows the restricted flow to the supply path Y1, and allows the flow to the supply path Z1. In the left position). Since the flow from the pump 15 to the supply path Z1 at the second position and the flow from the pump 15 to the supply path Y1 at the third position are both made through an orifice provided in the spool of the electromagnetic valve 17, the flow rate thereof is There are few restrictions. The solenoid valve 17 has a built-in solenoid and spring for driving the spool. Among the built-in solenoids, the solenoid that drives to the second position (hereinafter, right-handed solenoid) is excited. When the solenoid that drives to the third position (hereinafter referred to as a left-handed solenoid) is excited, the position is switched to the third position, and when none of the solenoids are excited, the spring is returned to the first position.

  The steering valve 19 is a manual switching valve having a metering mechanism that is mechanically coupled to the steering handle 7. The steering valve 19 is a hydraulic valve that is supplied to the steering cylinder 4 by the metering mechanism according to the operation of the steering handle 7. The amount is adjusted and its position is switched. That is, when the steering handle 7 is operated to rotate clockwise, the hydraulic oil is supplied to one oil chamber (left oil chamber) provided in the steering cylinder 4 and is recovered from the other oil chamber (right oil chamber). Switch to the swivel position. When the steering handle 7 is operated to rotate counterclockwise, the steering wheel 7 is switched to the left-turning position where hydraulic oil is collected from one oil chamber (left oil chamber) and supplied to the other oil chamber (right oil chamber). . When the operation of the steering handle 7 is stopped, it is returned to the neutral position where the flow of hydraulic fluid to and from the steering cylinder 4 is blocked by the built-in spring.

The lift valve 20 is a manual switching valve that is connected to the lift cylinder 12 by hydraulic piping and mechanically coupled to the lift lever 8. When the lift lever 8 is operated forward (backward when viewed from the driver), it is switched to the lowered position, and when it is operated backward (frontward when viewed from the driver), it is switched to the raised position. The spring is returned to the neutral position.
The tilt valve 21 is a manual switching valve that is connected to the tilt cylinder 13 by hydraulic piping and mechanically coupled to the tilt lever 9. When the tilt lever 9 is operated forward (backward when viewed from the driver), the tilt lever 9 is switched to the forward tilt position. When the tilt lever 9 is operated rearward (frontward when viewed from the driver), the tilt lever 9 is switched to the rearward tilt position. The spring is returned to the neutral position.

  The vehicle body 1 is provided with a control device 22 for controlling the motor 16 and the electromagnetic valve 17 described above. As shown in FIG. 3, signals from the seat switch 6a, the steering sensor 7a, the lift switch 8a, and the tilt switch 9a are input to the control device 22, and the control device 22 rotates the rotation speed of the motor 16 according to these signals. And the switching control of the electromagnetic valve 17 is performed.

  The control device 22 determines whether or not the steering handle 7 is operated based on the operation torque detected by the steering sensor 7a, and rotates the motor 16 at a predetermined speed if the steering handle 7 is operated. As a result, the pump 15 is driven and hydraulic oil is discharged toward the electromagnetic valve 17. Even if the steering handle 7 is not operated, the controller 22 determines that if the lift lever 8 is raised and the lift switch 8a is turned on, or if the tilt lever 9 is operated and the tilt switch 9a is turned on, the motor 16 Is rotated at a predetermined speed.

Further, as shown in FIG. 4, the control device 22 determines whether or not the seat switch 6a is off (S1), and if the seat switch 6a is off, that is, if there is no driver on the seat 6 (YES in S1). ) Exciting the left moving solenoid to switch the electromagnetic valve 17 to the third position (S2). Further, the control device 22 determines whether or not the operation torque detected by the steering sensor 7a is less than a predetermined threshold value (S3). If the operation torque is less than the threshold value, that is, the driver is not grasping the steering handle 7. If so (YES in S3), the left-hand solenoid is excited to switch the electromagnetic valve 17 to the third position (S2).
As a result, the hydraulic oil from the pump 15 mainly flows to the lift valve 20 and the tilt valve 21 through the supply path Z1, and a part flows to the steering valve 19 through the supply path Y1. At this time, since it is not necessary to supply hydraulic oil to the steering cylinder 4, the hydraulic oil is recovered as it is to the tank 14 through the recovery path Y3.

If the driver is on the seat 6 (NO in S1) and the driver is holding the steering handle 7 (NO in S3), the control device 22 determines whether both the lift switch 8a and the tilt switch 9a are off. Is determined (S4). If both switches are off, that is, whether the lift lever 8 has been lowered or not operated at all, and if the tilt lever 9 has not been operated (YES in S4), the control device 22 has a right-hand solenoid. To switch the electromagnetic valve 17 to the second position (S5).
As a result, the hydraulic oil from the pump 15 mainly flows to the steering valve 19 through the supply path Y1, and partly flows to the lift valve 20 and the tilt valve 21 through the supply path Z1. At this time, since it is not necessary to supply hydraulic oil to the lift cylinder 12 and the tilt cylinder 13, the hydraulic oil is recovered as it is into the tank 14 through the recovery path Z3.

If at least one of the switches is on, that is, if the lift lever 8 is raised or the tilt lever 9 is operated (NO in S4), the controller 22 does not excite both solenoids, thereby The valve 17 is switched to the first position.
As a result, the hydraulic oil from the pump 15 flows to the priority valve 18 through the supply path X1 and is divided into the flow of the supply path Y2 and the flow of the supply path Z2 in the priority valve 18. Accordingly, the hydraulic oil is supplied to the steering cylinder 4 through the steering valve 19, and is supplied to the lift cylinder 12 through the lift valve 20 (or through the tilt valve 21 to the tilt cylinder 13).

According to such an embodiment, if the steering handle 7 is operated and the lift lever 8 is raised or the tilt lever 9 is operated, the electromagnetic valve 17 is switched to the first position. By switching the priority valve 18, hydraulic oil can be supplied to the steering cylinder 4, the lift cylinder 12 and the tilt cylinder 13 to operate simultaneously.
If the lift lever 8 is not raised and the tilt lever 9 is not operated, the electromagnetic valve 17 is switched to the second position, so that the hydraulic oil is preferentially and efficiently applied to the steering cylinder 4. Can be supplied. In the second position, since the hydraulic oil is somewhat flowing toward the lift valve 20 and the tilt valve 21, the electromagnetic valve 17 is then switched to the first position or the third position, and the lift cylinder 12 and the tilt cylinder 13 are switched. When supplying the hydraulic oil, it is possible to suppress the occurrence of a shock due to the sudden start of the hydraulic oil.
Further, if the driver is not on the seat 6 or the driver is not grasping the steering handle 7, the electromagnetic valve 17 is switched to the third position, so that the lift cylinder 12 and the tilt cylinder 13 have priority. In addition, the hydraulic oil can be supplied efficiently and efficiently. In the third position, since the hydraulic oil is made to flow somewhat toward the steering valve 19, the electromagnetic valve 17 is then switched to the first position or the second position, and when the hydraulic oil is supplied to the steering cylinder 4, It is possible to suppress the occurrence of shock due to the sudden start of hydraulic oil.

1 is a side view of a forklift according to an embodiment of the present invention. It is a hydraulic circuit diagram of the Example of this invention. It is a functional block diagram of the Example of this invention. It is a control flowchart of the Example of this invention.

Explanation of symbols

1 Car body 3 Rear wheel 4 Steering cylinder 6 Seat 6a Seat switch 7 Steering handle 7a Steering sensor 8 Lift lever 8a Lift switch 9 Tilt lever 9a Tilt switch 10 Mast 11 Fork 12 Lift cylinder 13 Tilt cylinder 15 Pump 17 Electromagnetic valve 18 Priority valve 19 Steering valve 20 Lift valve 21 Tilt valve 22 Control device X1 Supply path Y1 Supply path Y2 Supply path Z1 Supply path Z2 Supply path

Claims (6)

An industrial vehicle hydraulic system that supplies hydraulic oil to another actuator by a pump that supplies hydraulic oil to a steering actuator that operates in response to a steering operation.
A priority valve that is connected to the steering actuator and the other actuator by hydraulic piping, and is switchable to a state that allows the flow of hydraulic oil from the pump to any one of the actuators, the priority valve, and the pump; An electromagnetic valve provided between the steering actuator and the other actuator via hydraulic piping, and a control device for controlling the electromagnetic valve.
The electromagnetic valve allows a flow of hydraulic oil from the pump to the priority valve, and prevents a flow of hydraulic oil from the pump to the priority valve in a first state in which the flow to the actuators is blocked. The second state allowing the flow to the steering actuator, and the third state allowing the flow of hydraulic oil to the other actuators by blocking the flow from the pump to the priority valve can be switched. Industrial vehicle hydraulic system characterized by   The electromagnetic valve blocks the flow of hydraulic oil from the pump to the priority valve in the second state, and mainly allows the flow to the steering actuator. In the third state, the electromagnetic valve 2. The hydraulic system for an industrial vehicle according to claim 1, wherein the hydraulic oil is prevented from flowing from the pump to the priority valve and mainly allowed to flow to the other actuator. Provided with driver detection means for detecting the presence or absence of the driver boarding the vehicle,
3. The industrial vehicle according to claim 1, wherein the control device controls the electromagnetic valve to switch to the third state when a driver is not on board. 4. Hydraulic system. A handle detecting means for detecting whether or not the handle is operated;
4. The control device according to claim 1, wherein the control device controls the electromagnetic valve to switch to the third state when the handle is not operated. 5. Industrial vehicle hydraulic system. An operation tool detection means for detecting the presence or absence of operation of an operation tool operated by a driver to operate the other actuator;
5. The control device according to claim 1, wherein the control device controls the electromagnetic valve to switch to the second state when the operation tool is not operated. 6. Industrial vehicle hydraulic system.   6. The control device according to claim 5, wherein when the handle is operated and the operation tool is operated, the control device controls the electromagnetic valve to be switched to the first state. Industrial vehicle hydraulic system.

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