JPH07172328A - Fluid pressure circuit in cargo handling vehicle - Google Patents

Abstract

PURPOSE:To improve the performance of cargo handling operation without enlarging a motor and a fluid pressure pump on a cargo handling operation side. CONSTITUTION:A steering control valve 5 and a steering operation hydraulic pump 3 to be driven by a steering motor 2 ar connected to each other by means of a steering flow passage 4. A cargo handling operation hydraulic pump 8 and a cargo handling control valve 10 are connected to each other by means of a cargo handling flow passage 9. A bypass flow passage 13 diverges from the steering flow passage 4 and joint the cargo handling flow passage 9. An electromagnetic opening/closing valve 14 is interposed in the bypass flow passage 13. A pressure sensing sensor 15 is provided at the steering control valve 5. A micro switch 16 is provided at a cargo handling lever 11. A controller 1 controls the steering motor 2, a cargo handling motor 7, and the electromagnetic opening/closing valve 14 according to signals from the pressure sensing sensor 15 and the microswitch 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling vehicle such as a forklift truck which operates a power steering function and a cargo handling function by fluid pressure, and more particularly to a fluid pressure circuit in the cargo handling vehicle.

[0002]

2. Description of the Related Art In a fluid pressure circuit of a cargo handling vehicle having a power steering function and a cargo handling function, generally, a working fluid from one fluid pressure source is passed through a shunt valve to provide a steering circuit and a cargo handling fluid. It is configured so that the voltage is divided and supplied to the pressure circuit. Further, as disclosed in Japanese Utility Model Laid-Open No. 61-185795, in order to improve the cargo handling operation performance, when the power steering is inoperative, the fluid for steering operation is changed by switching the solenoid valve or the like. There is also a configuration in which the working fluid from the pressure pump is preferentially supplied to the cargo handling circuit.

However, in the above-mentioned configuration, the working fluid from one fluid pressure source is shared by the fluid pressure circuits of the cargo handling operation system and the steering operation system, but compared with the load during steering operation. Since the load during the cargo handling operation is larger, a large-sized drive with a large output is used as the drive means for driving the fluid pressure source compared to the configuration in which the working fluid from the fluid pressure source is supplied only to the steering operation system. I have to do it. For example, even in the mode in which only the steering operation is operated, it is necessary to drive the large motor to supply the fluid pressure, and the energy efficiency is not good.

For this reason, it cannot be applied to a battery vehicle or the like which is driven by a storage battery mounted on the vehicle body and is required to minimize energy consumption. Therefore, in the above battery vehicles and the like, it is generally practiced to separately mount a motor dedicated to the steering system and a fluid pressure pump so that the steering circuit and the cargo handling circuit have independent fluid pressure sources. Has been done.

In this case, a necessary and sufficient motor and fluid pressure pump corresponding to the load during steering operation are mounted, and the energy efficiency is improved as compared with the above.

[0006]

However, even in the battery vehicle as described above, it is required to improve the performance of the cargo handling operation, and as a measure of the performance, the moving speed of the cargo handling device such as the lift speed of the mast is required. It has become an index.
In order to cope with this, conventionally, it is necessary to adopt a cargo handling motor having a large output or a large cargo handling fluid pressure pump as a driving unit of the cargo handling fluid pressure pump.

However, the use of a larger cargo handling motor or cargo handling operation fluid pressure pump increases the cost, and occupies a larger occupied space, which restricts the mounting space. The present invention has been made in view of the above problems, and an object thereof is to improve cargo handling operation performance without increasing the size of a cargo handling operation side motor or fluid pressure pump.

[0008]

To achieve the above object, a fluid pressure circuit in a cargo handling vehicle according to the present invention comprises a steering operation fluid pressure pump and a cargo handling operation fluid pressure pump as fluid pressure sources, The working fluid from the steering fluid pressure pump can be supplied to the steering circuit through the steering flow path, and the working fluid from the cargo handling operation fluid pressure pump is used for cargo handling through the cargo handling flow path. In a cargo handling vehicle capable of supplying to the circuit, a bypass flow path that connects the discharge side of the steering operation fluid pressure pump and the cargo handling circuit and a working fluid discharged from the steering operation fluid pressure pump are steered. It is characterized in that only one of the flow channels and the bypass flow channel are provided, or a distribution means for distributing them to both at a predetermined ratio.

At this time, when the cargo handling operation is performed without the steering operation, the discharge side from the steering fluid pressure pump is
It is preferable to provide a distribution control unit that controls so as to communicate only with the bypass flow path side via the distribution unit. Or
Steering operation detecting means for detecting the presence / absence of steering operation, cargo handling operation detecting means for detecting the presence / absence of cargo handling operation, steering fluid pressure pump driving means for driving a fluid pressure pump for steering operation, steering operation detecting means, cargo handling operation A controller that is connected to the detection means, the distribution means, and the steering fluid pressure pump drive means, and that controls the distribution means and the steering fluid pressure pump drive means by signals from the steering operation detection means and the cargo handling operation detection means. When the controller determines that there is a steering operation and a cargo handling operation based on signals from the steering operation detecting means and the cargo handling operation detecting means, the controller drives the steering fluid pressure pump driving means and also through the distributing means. The discharge side of the steering operation fluid pressure pump is preferentially connected to the steering flow path side, and the steering operation detection means and the cargo handling operation detection means When it is determined that the steering operation is performed and the cargo handling operation is not performed, the steering fluid pressure pump drive means is driven, and the discharge side of the steering operation fluid pressure pump is set only to the steering flow path side through the distribution means. In addition, when it is determined that there is no steering operation and there is a cargo handling operation based on signals from the steering operation detecting means and the cargo handling operation detecting means, the steering fluid pressure pump driving means is driven and the distribution means is used. When the discharge side of the steering operation fluid pressure pump is communicated with the bypass flow passage side, and when it is determined that there is no steering operation and no cargo handling operation by the signals from the steering operation detection means and the cargo handling operation detection means, It is characterized in that the pressure pump driving means is stopped.

Further, when the bypass flow path is branched from the steering flow path and an opening / closing valve forming a distribution means is provided in the bypass flow path, the pressure holding means is interposed in the bypass flow path. Good. Further, a check valve may be provided in the steering passage. Further, a closed center type valve may be used as a steering control valve that connects the steering flow path and the cylinder portion of the power steering as the steering circuit.

Further, a priority valve is provided in the steering passage at a position closer to the fluid pressure pump for steering operation than the steering control valve for communicating the steering passage with the cylinder portion of the power steering as the steering circuit. Then
Moreover, it is preferable that the surplus flow outlet port of the priority valve is connected to the cargo handling circuit.

[0012]

By the bypass flow passage, the working fluid from the steering operation fluid pressure pump can be supplied to the cargo handling circuit. When the steering operation is not performed, it is not necessary to supply the working fluid to the steering circuit side. Therefore, the working fluid from the steering operation fluid pressure pump is supplied to the cargo handling circuit side via the distribution means.

As a result, the amount of working fluid supplied to the cargo handling circuit is increased without increasing the size of the cargo handling fluid pressure pump, thereby improving the cargo handling performance when the steering operation is not performed. Further, with the configuration according to claim 3, when both the steering operation and the cargo handling operation are operated, the fluid pressure source is independently actuated as in the conventional case,
The working fluid from the steering fluid pressure pump is supplied to the steering circuit.

When only the cargo handling operation is performed without performing the steering operation, the steering operation fluid pressure pump is driven via the steering drive means such as a motor and the driving fluid pressure pump is operated via the distribution means. By communicating with the bypass flow path side, the working fluid from the steering operation fluid pressure pump is supplied to the cargo handling circuit. As a result, the cargo handling operation performance is improved such that the moving speed of the cargo handling device such as a mast driven by the cargo handling circuit is increased.

When neither the steering operation nor the cargo handling operation is performed, the drive of the fluid pressure pump is stopped to prevent unnecessary energy consumption. Further, when the opening / closing valve forming the distributing means is provided in the bypass passage as in claim 4, if the opening / closing valve fails and remains in the open state, the fluid pressure for steering operation is also maintained during steering operation. A part of the working fluid discharged from the pump may flow to the cargo handling fluid pressure circuit, and the supply amount of the working fluid to the steering circuit may be insufficient, so that a predetermined power steering function may not be ensured.

In view of this, by providing the pressure holding means in the bypass passage, the fluid pressure in the bypass passage is kept at a predetermined pressure even if the on-off valve fails in the normally open state as described above. Therefore, a predetermined fluid pressure is secured for the steering circuit. As a result, a predetermined power steering pressure is secured even if the open / close valve fails in the normally open state while the vehicle is traveling, and traveling safety is guaranteed.

Further, by providing the check valve in the steering passage, the backflow of the working fluid from the steering circuit is suppressed when the steering operation is stopped, that is, when the steering operation hydraulic pressure pump is stopped. A predetermined residual pressure is secured in the steering circuit.
As a result, the time required for the steering circuit to reach the predetermined set pressure again by driving the steering operation hydraulic pump again improves the responsiveness of the steering operation.

Further, by adopting a closed center type valve as the steering control valve, the fluid is supplied from the steering fluid pressure pump through the steering passage when there is no load, that is, when the steering operation is not performed. The working fluid to be discharged does not return to the tank. If an open center type valve is adopted as the steering control valve, it is necessary to separately provide an opening / closing valve or the like for suppressing the circulation of the working fluid to the tank in the steering flow path.

Further, the flow rate required for the steering system corresponds to the speed at which the steering wheel is rotated by the operator, and in general, the minimum flow rate to be ensured is known at the time of design. Therefore, by providing the priority valve as described in claim 7, it becomes possible to supply the remaining surplus flow rate that secures the necessary flow rate preferentially to the steering system to the cargo handling circuit side. This improves the cargo handling operation performance while performing the steering operation.

[0020]

Embodiments of the present invention will be described with reference to the drawings.
In the following examples, the case where the present invention is applied to a battery-powered forklift truck as an example of a cargo handling vehicle,
The case where hydraulic fluid is used as the fluid will be described. First, the configuration will be described. As shown in FIG. 1, the steering motor 2 is drive-controlled by a battery (not shown) as a power source in accordance with a command from the controller 1, and the steering motor 2 drives the steering hydraulic pump 3 to operate. It can be driven. One end of the steering flow path 4 is connected to the discharge side of the steering operation hydraulic pump 3, and the other end of the steering flow path 4 is
It is connected to the input side port of the steering control valve 5, which constitutes a steering circuit together with the power cylinder device 6.

The steering control valve 5 is a closed center type 4-port 3-position switching valve whose switching is controlled by rotating the steering wheel through the steering operation device. Accordingly, a function of supplying hydraulic oil to the first chamber 6a of the power cylinder device 6 to move the piston rod to the second chamber 6b side, and a function of supplying hydraulic oil to the second chamber 6b of the power cylinder device 6 to operate the piston It has a function of moving the rod to the first chamber 6a side. In the power cylinder device 6, the cylinder device main body is supported on the vehicle body side, and the piston rod is supported by the steering gauge to perform assist control of the steering force.

The cargo handling motor 7 is drive-controlled by a battery (not shown) as a power source in response to a command from the controller 1, and the cargo handling motor 7 can be driven to drive the cargo handling hydraulic pump 8. One end of the cargo handling passage 9 is connected to the discharge side of the cargo handling hydraulic pump 8, and the other end of the cargo handling passage 9 constitutes a cargo handling circuit together with the lift cylinder device 12. It is connected to the input side port of the valve 10.

The cargo handling control valve 10 is a closed center type 4-port three-position switching valve which is switch-controlled by a cargo handling lever 11, and the lift cylinder device 12 of the lift cylinder device 12 is set in accordance with the setting from the cargo handling lever 11. It has a function of supplying hydraulic oil to the first chamber 12a to move the piston rod upward, and a function of supplying hydraulic oil to the second chamber 12b of the lift cylinder device 12 to move the piston rod downward. The lift cylinder device 12
The cylinder device body is supported on the vehicle body side, and the upper part of the piston rod is fixed to the lift bracket to control the fork up and down.

Further, the bypass flow path 13 is branched from the middle of the steering flow path 4, and the other end of the bypass flow path 13 joins the middle of the cargo handling flow path 9. Its bypass channel 1
In the middle of 3, an electromagnetic opening / closing valve 14 and a check valve 14a, which form a distributing means, are provided. Check valve 14
“A” permits only the flow of the hydraulic oil in the bypass flow passage 13 from the steering flow passage 4 side toward the cargo handling flow passage 9 side and prevents the flow in the opposite direction.

Further, the solenoid opening / closing valve 14 is operated by a command from the controller 1, and the bypass passage 13 is operated.
The flow of hydraulic oil inside can be opened and closed. Further, the steering control valve 5 is provided with a pressure detection sensor 15 which constitutes steering operation detection means. The pressure sensor 15 can detect the presence or absence of a steering operation by the pressure in the steering control valve 5 and can supply a presence signal or a absence signal to the controller 1.

Further, a micro switch 16 constituting a cargo handling operation detecting means is provided for the cargo handling lever 11. The micro switch 16 can detect the operation of the cargo handling lever 11 and supply a signal corresponding to the presence or absence of the cargo handling operation to the controller 1. The controller 1
The steering motor 2, the cargo handling motor 7, and the electromagnetic opening / closing valve 14 are controlled according to signals from the pressure detection sensor 15 and the micro switch 16.

More specifically, when the controller 1 inputs the presence signal from the pressure detection sensor 15 and the presence signal from the micro switch 16, it determines that the steering operation and the cargo handling operation are performed, and the steering motor 2 is operated. Also, a driving signal is supplied to the cargo handling motor 7 and a closing command is transmitted to the electromagnetic opening / closing valve 14. When the presence signal is input from the pressure detection sensor 15 and the absence signal is input from the micro switch 16, it is determined that the steering operation is performed and the cargo handling operation is stopped, and the drive signal is output to the steering motor 2. Then, a stop signal is supplied to the cargo handling motor 7, and a closing command is transmitted to the electromagnetic opening / closing valve 14.

Further, when the absence signal is input from the pressure sensor 15 and the presence signal is input from the micro switch 16, it is determined that the steering operation is stopped and the cargo handling operation is performed, and the steering motor 2 and the cargo handling operation are determined. A drive signal is supplied to the motor 7, and an opening command is transmitted to the electromagnetic opening / closing valve 14. Further, when the absence signal is input from the pressure sensor 15 and the absence signal is input from the micro switch 16,
Judging that the steering operation and cargo handling operation are stopped,
A stop signal is supplied to the steering motor 2 and the cargo handling motor 7, and a closing command is transmitted to the electromagnetic opening / closing valve 14.

In the hydraulic circuit configured as described above, when the operator rotates the steering wheel, the steering control valve 5 is switched to the steering position via the steering operation device. Then, the steering control valve 5
The pressure sensor 15 indicates that the vehicle has switched to the steering operation.
Detects the signal and supplies the signal to the controller 1. At this time, when the cargo handling lever 11 is operated and the cargo handling controller valve 10 is controlled to be switched to the lift up position or the lift position, when the presence signal from the micro switch 16 is input to the controller 1, the controller 1
Supplies a drive signal to the steering motor 2 and the cargo handling motor 7, and also transmits a closing command to the electromagnetic opening / closing valve 14.

As a result, the electromagnetic opening / closing valve 14 is operated to the closed position to close the flow of the hydraulic oil in the bypass flow passage 13, and the hydraulic oil flowing in the steering flow passage 4 flows to the cargo handling control valve 10 side. Is blocked. When the steering motor 2 is driven, the steering hydraulic pump 3 is driven.
Is driven to supply hydraulic oil to the steering control valve 5 via the steering flow path 4, and the hydraulic oil is supplied to one of the first and second chambers 6b of the power cylinder device 6. At the same time, the hydraulic oil in the other chamber returns to the tank 17 via the steering control valve 5 and the steering operation is performed.

On the other hand, when the cargo handling motor 7 is driven, the cargo handling hydraulic pump 8 is driven, hydraulic oil is supplied to the cargo handling control valve 10 through the cargo handling flow passage 9, and its operation is further performed. Oil is supplied to the lift cylinder device 12, and the lifting operation of the lift is performed. Further, when the steering control valve 5 is switched to the steering position and the cargo handling control valve 10 is switched to the neutral position via the steering operation device, the controller 1 inputs the presence signal from the pressure detection sensor 15. Micro switch 1
6, a no signal is input, a closing command is transmitted to the electromagnetic opening / closing valve 14 to keep the flow of the bypass passage 13 closed, and a stop signal is supplied to the cargo handling motor 7 to operate the cargo handling hydraulic pressure. The pump 8 is stopped.

On the other hand, a drive signal is supplied to the steering motor 2 to start driving the steering motor 2, but the driving is continued. At this time, the cargo control valve 1
0 is switched to the neutral position, and the position is held on the piston rod of the lift cylinder device 12. Further, the hydraulic oil discharged from the steering operation hydraulic pump 3 is supplied to the steering control valve 5 via the steering flow path 4 and then to the power cylinder device 6 to perform the steering operation.

Further, the steering control valve 5 is controlled to be switched to the neutral position and the cargo handling control valve 10 is used.
When is controlled to switch to the cargo handling position, the controller 1 inputs a no signal from the pressure detection sensor 15 and a presence signal from the micro switch 16. Then, the controller 1 transmits an opening command to the electromagnetic opening / closing valve 14 to enable the working oil to flow in the bypass passage 13, and also supplies a drive signal to the steering motor 2 and the cargo handling motor 7. .

Then, the hydraulic oil from the cargo handling hydraulic pump 8 is supplied to the cargo handling control valve 10. At the same time, hydraulic oil is also discharged from the steering operation hydraulic pump 3, but since the steering control valve 5 is set to the neutral position, it is not supplied to the steering control valve 5 and the bypass flow passage is not supplied. It is supplied to the cargo control valve 10 via 13.

The cargo handling control valve 10 supplies the hydraulic oil supplied from both the cargo handling hydraulic pump 8 and the steering hydraulic pump 3 to the lift cylinder device 12 to carry out the cargo handling operation. At this time, the amount of hydraulic oil supplied per time to the cargo handling control valve 10 and the lift cylinder is larger than that from only the cargo handling hydraulic pump 8, and the lifting speed and the lowering speed of the lift are higher than in the conventional case. Will be implemented at a faster rate.

Further, the steering control valve 5 is controlled to be switched to the neutral position, and the cargo control valve 10 is controlled.
When the control is switched to the neutral position, the controller 1 inputs a no signal from the pressure sensor 15 and a no signal from the microswitch 16. Then, the controller 1 supplies a stop signal to the steering motor and the cargo handling motor, and at the same time, transmits a closing command to the electromagnetic opening / closing valve 14.

Then, the electromagnetic opening / closing valve 14 is closed, the flow of hydraulic oil in the bypass passage 13 is blocked, and the steering system and the cargo handling system are separated. Further, since the cargo handling operation hydraulic pump 8 is stopped and the cargo handling control valve 10 is in the neutral position, the hydraulic oil in the cargo handling flow passage 9 passes through the return port of the cargo handling control valve 10. Return to tank 17.

On the other hand, although the steering hydraulic pump 3 is also stopped, since the steering control valve 5 is a closed center type, the hydraulic oil in the steering flow path 4 passes through the return port of the steering control valve 5. And is prevented from returning to the tank 17. At this time, since the electromagnetic opening / closing valve 14 is closed, the hydraulic oil in the steering flow passage 4 is transferred to the bypass flow passage 13
Does not flow through the cargo handling control valve 10 and the cargo handling hydraulic pump 8 side.

Thus, in the hydraulic circuit of the above embodiment,
The lift cylinder device 12 when the steering operation is stopped without enlarging the cargo handling motor 7 or the cargo handling hydraulic pump 8
By increasing the amount of hydraulic oil supplied to the lift, the lifting speed of the lift can be set faster than before. Further, when the steering operation and the cargo handling operation are not performed, the steering motor 2 and the cargo handling motor 7 are stopped, and unnecessary energy consumption is suppressed.

Although a closed center type valve is used as the cargo handling control valve 10 in the above embodiment, an open center type valve may be used.
However, as it is, when the hydraulic oil from the steering hydraulic pump 3 is supplied to the cargo handling control valve 10 through the bypass passage 13, a part of the hydraulic oil discharged from the steering hydraulic pump 3 is supplied. 2 returns to the tank 17 via the return port of the steering control valve 5, so that the bypass flow path 13 branch point in the steering flow path 4 and the input port of the steering control valve 5 as shown in FIG. An electromagnetic opening / closing valve 20 is interposed between the electromagnetic opening / closing valve 20 when the steering control valve 5 is in the neutral position.
It is necessary to control so that it will be in a closed state.

Further, in the above embodiment, the case where the hydraulic pressure is used as the fluid pressure has been described, but the pneumatic pressure may be used. Further, although the above embodiment has been described by taking an example of a forklift truck as a cargo handling vehicle, it may be applied to other types of forklift trucks and other cargo handling vehicles.

Next, the second embodiment will be described. As shown in FIG. 3, the basic configuration of the hydraulic circuit of the second embodiment is the same as that of the first embodiment, except that the bypass passage 13 is provided with pressure holding means. The pressure holding means is composed of a throttle 21, and the throttle 21 is interposed in the bypass flow path 13.

With the diaphragm 21 not installed,
If the electromagnetic opening / closing valve 14 fails and falls into the normally open failure mode, the hydraulic oil discharged from the steering operation hydraulic pump 3 flows into the cargo handling system through the bypass flow passage 13 during the steering operation. However, the power steering function cannot be exerted without the desired hydraulic oil being secured in the steering system. On the other hand, if the throttle 21 is formed as in the second embodiment, in the unlikely event that the electromagnetic opening / closing valve 14 fails and the steering operation is performed in the normally open failure mode, the steering operation is performed. A part of the hydraulic oil discharged from the hydraulic pump 3 for use flows to the bypass flow path 13 side, but a predetermined fluid pressure is held by the throttle 21 and a predetermined fluid pressure for the steering system is secured.

In particular, since the steering operation has a small load during traveling, the pressure holding by the throttle 21 is sufficient.
Deterioration of steering operability during traveling is avoided, and safety is improved. Other actions and effects are similar to those of the first embodiment. Although the throttle 21 is used as the pressure holding means in the second embodiment, other known pressure holding means such as a relief valve may be used.

However, when a relief valve is used as the pressure holding means, it is necessary to set the line pressure of the cargo handling circuit to be higher than the pressure set for the relief valve in order for hydraulic oil to flow to the cargo handling circuit side. By setting the line pressure on the cargo handling circuit side higher than the load of the steering system in the traveling mode, the safety of the steering operation during traveling is ensured. Also,
In the second embodiment, a torque sensor 22 is attached to the steering shaft instead of the pressure sensor 15 as the steering operation detecting means, and the torque sensor 22 detects the rotational torque of the steering wheel to determine whether or not the steering operation is performed. I am trying.

Next, the third embodiment will be described. As shown in FIG. 4, the basic configuration of the hydraulic circuit of the third embodiment is equivalent to that of the first and second embodiments, and the check valve 23 is provided in the middle of the steering passage 4. The difference is that you did. The check valve 23 permits the flow toward the steering control valve 5 and also allows the steering operation hydraulic pump 3 to flow.
It blocks the flow to the side.

By providing the check valve 23, the steering operation is stopped, that is, the control valve 5 for steering.
When is in the neutral position and the steering operation hydraulic pump 3 is stopped, the reverse flow of hydraulic oil to the steering operation hydraulic pump 3 side is suppressed as much as possible to secure the residual pressure. This improves the responsiveness of the steering operation when the steering operation is performed next. Other actions and effects are similar to those of the first and second embodiments.

Although the check valve 23 is interposed between the branch point of the bypass passage 13 and the steering control valve 5 in FIG. 4, the check hydraulic valve 3 of the steering operation and the bypass passage 13 are provided. You may intervene between a branch point. Next, the fourth
Examples will be described. As shown in FIG. 5, the basic configuration of the hydraulic circuit of the fourth embodiment is the same as that of the first and second embodiments, except that the priority passage 24 is provided in the steering passage 4. It's different.

The priority valve 24 uses the steering circuit as a priority circuit and connects the surplus flow rate take-out port to the cargo handling passage 9 through the second bypass passage 13. In addition, in FIG. 5, 25 is a check valve. With this configuration, when the hydraulic oil is supplied from the steering operation hydraulic pump 3 to the steering control valve 5 via the steering flow path 4, the priority valve 24 controls the flow rate required in the steering system. It is possible to secure and send the remaining surplus flow rate to the cargo handling system via the second bypass flow path 13,
Even when the steering operation and the cargo handling operation are performed at the same time, the hydraulic oil is supplied to the cargo handling circuit more than before, and the cargo handling operability is improved.

Other functions and effects are similar to those of the first and second embodiments. In all of the above-mentioned embodiments, the battery-carrying vehicle is described as the cargo-handling vehicle. However, the cargo-carrying vehicle is not limited to the battery-carrying vehicle and is an engine car. It is also applicable to a vehicle in which is independently mounted.

Further, an alarm device for warning the failure of the electromagnetic on-off valve 14 may be provided.

[0052]

As described above, in the fluid pressure circuit of the cargo handling vehicle according to the present invention, the steering operation can be performed by effectively utilizing the pressure fluid in the steering system without changing the fluid pressure components on the cargo handling side. It is possible to improve the cargo handling operation performance in the non-implementation state. Furthermore, by providing the priority valve, the cargo handling operation performance can be improved without changing the fluid pressure components on the cargo handling side even during the steering operation.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a fluid pressure circuit in a cargo handling vehicle according to a first embodiment of the present invention.

FIG. 2 is a basic configuration diagram showing a part of another fluid pressure circuit in the cargo handling vehicle according to the first embodiment of the present invention.

FIG. 3 is a basic configuration diagram showing a fluid pressure circuit in a cargo handling vehicle according to a second embodiment of the present invention.

FIG. 4 is a basic configuration diagram showing a fluid pressure circuit in a cargo handling vehicle according to a third embodiment of the present invention.

FIG. 5 is a basic configuration diagram showing a fluid pressure circuit in a cargo handling vehicle according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 controller 2 steering motor 3 steering hydraulic pump 4 steering flow path 5 steering control valve 6 power cylinder device 7 cargo handling motor 8 cargo handling hydraulic pump 9 cargo handling flow path 10 cargo handling control valve 13 bypass flow path 14 Electromagnetic on-off valve 15 Pressure sensor 16 Micro switch 21 Throttle 23 Check valve 24 Priority valve

Claims (7)

[Claims] 1. A steering operation fluid pressure pump and a cargo handling operation fluid pressure pump are provided as fluid pressure sources, and working fluid from the steering operation fluid pressure pump is supplied to a steering circuit through a steering flow path. In the cargo-handling vehicle that is capable of supplying working fluid from the cargo-handling operation fluid pressure pump to the cargo-handling circuit through the cargo-handling passage, the discharge side of the steering operation fluid pressure pump The bypass flow path communicating with the cargo handling circuit and the working fluid discharged from the steering operation fluid pressure pump are supplied to the steering flow path and the bypass flow path only in one of the flow paths or at a predetermined ratio. A fluid pressure circuit in a cargo handling vehicle, comprising: a distribution means for distributing to both. 2. A distribution control means for controlling a discharge side from a fluid pressure pump for steering operation so as to communicate only with the bypass flow path side through a distribution means when carrying out a cargo handling operation without performing a steering operation. 3. The method according to claim 1, wherein
A fluid pressure circuit in the cargo handling vehicle described. 3. Steering operation detecting means for detecting the presence / absence of steering operation, cargo handling operation detecting means for detecting the presence / absence of cargo handling operation, steering fluid pressure pump driving means for driving a fluid pressure pump for steering operation, and steering operation. Detection means, cargo handling operation detection means,
A controller that is connected to the distributing means and the steering fluid pressure pump driving means, and controls the distributing means and the steering fluid pressure pump driving means by signals from the steering operation detecting means and the cargo handling operation detecting means, When the controller determines that there is a steering operation and there is a cargo handling operation based on signals from the steering operation detecting means and the cargo handling operation detecting means, the controller drives the steering fluid pressure pump driving means and also performs the steering operation via the distributing means. When the discharge side of the hydraulic fluid pump is preferentially connected to the steering flow path side, and when it is determined that there is a steering operation and no cargo handling operation by the signals from the steering operation detecting means and the cargo handling operation detecting means, The steering fluid pressure pump drive means is driven, and the discharge side of the steering operation fluid pressure pump is communicated only with the steering flow path side via the distribution means. If it is determined that there is no steering operation and there is a cargo handling operation based on the signals from the steering operation detecting means and the cargo handling operation detecting means, the steering fluid pressure pump drive means is driven and the steering operation fluid is supplied via the distributing means. Communicate the discharge side of the pressure pump to the bypass flow path side,
2. The cargo handling vehicle according to claim 1, wherein the steering fluid pressure pump drive means is stopped when it is determined that there is no steering operation and no cargo handling operation based on signals from the steering operation detecting means and the cargo handling operation detecting means. Fluid pressure circuit in. 4. When the bypass flow path is branched from the steering flow path and an opening / closing valve forming a distribution means is provided in the bypass flow path, a pressure holding means is provided in the bypass flow path. The fluid pressure circuit in the cargo handling vehicle according to any one of claims 1 to 3. 5. The fluid pressure circuit in a cargo handling vehicle according to claim 1, wherein a check valve is provided in the steering passage. 6. A closed center type valve is used as a control valve for steering, which connects a steering flow path and a cylinder portion of a power steering as a steering circuit. A fluid pressure circuit in a cargo handling vehicle described in any one of 1. 7. A priority valve is provided in the steering flow passage at a position closer to a fluid pressure pump for steering operation than a steering control valve that connects a steering flow passage and a cylinder portion of a power steering as a steering circuit. The fluid pressure circuit in the cargo handling vehicle according to any one of claims 1 to 6, wherein the excess flow outlet port of the priority valve is communicated with the cargo handling circuit.