JP2970364B2 - Fluid pressure circuit in cargo handling vehicle - Google Patents

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 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 supplied to a steering circuit and a cargo handling fluid via a flow dividing valve. A configuration is adopted in which the current is divided and supplied to the pressure circuit. Further, as described in Japanese Utility Model Laid-Open Publication No. 61-185595, etc., in order to improve the cargo handling operation performance, when the power steering is inoperative, the steering operation fluid is switched by switching a solenoid valve or the like. Some are configured so that the working fluid from the pressure pump is preferentially supplied to the cargo handling circuit.

However, in the above-described configuration, the working fluid from one fluid pressure source is shared by the hydraulic circuits of the cargo handling system and the steering operation system. Since the load at the time of cargo handling operation is larger, a large output device with a large output is used as the driving means for driving the fluid pressure source, compared to a 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-sized motor to supply the fluid pressure, and the energy efficiency is not good.

[0004] For this reason, it is not possible to cope with a battery car or the like driven by a storage battery mounted on a vehicle body, in which energy consumption is to be minimized. Therefore, in the above-mentioned battery car, it is generally practiced to separately mount a motor and a fluid pressure pump dedicated to the steering system so that the steering circuit and the cargo handling circuit have independent fluid pressure sources. Have been.

[0005] In this case, a motor and a fluid pressure pump necessary and sufficient for the load at the time of the steering operation are mounted, and the energy efficiency is improved as compared with the above.

[0006]

However, even with the above-mentioned battery-powered vehicle, it is required to improve the performance of the cargo handling operation. As a standard of the performance, the moving speed of the cargo handling device such as the mast lift speed is required. It is the indicator.
To cope with this, conventionally, it is necessary to employ a large-load cargo handling motor or a large-sized cargo handling hydraulic pump as a driving means of the cargo handling hydraulic pump.

[0007] However, adopting a larger cargo handling motor or a fluid handling pump for cargo handling increases the cost and increases the occupied space, thereby limiting the mounting space. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to improve cargo handling operation performance without increasing the size of a motor or a hydraulic pump on the cargo handling side.

[0008]

In order to achieve the above-mentioned object, the hydraulic circuit in the cargo handling vehicle of the present invention is individually constructed.
Independently driven by each moving pump drive means
Includes a fluid pressure pump for steering operation fluid pressure pump and load <br/> officers operating as a fluid pressure source to be, for steering the working fluid from the steering operation fluid pressure pump via a steering channel In the cargo handling vehicle, which can be supplied to the circuit and the working fluid from the fluid handling pump can be supplied to the cargo handling circuit through the cargo handling flow path, A bypass flow path communicating the discharge side and the cargo handling circuit, and a working fluid discharged from the steering operation fluid pressure pump, the steering flow path and the bypass flow path, only one of the flow paths, or It is characterized by comprising: a distribution means for distributing to both a predetermined ratio.

Further, in the case of the loading operation without the steering operation, the discharge side of the steering operation fluid pressure pump, via a distribution means, the distribution control means for controlling so as to communicate only with the bypass flow Should be provided. A steering operation detecting means for detecting the presence or absence of a steering operation, a cargo handling operation detecting means for detecting the presence or absence of a cargo handling operation, a steering fluid pressure pump driving means for driving a steering hydraulic pump, a steering operation detecting means, A controller connected to the cargo handling operation detecting means, the distributing means, and the steering fluid pressure pump driving means, and controlling the distributing means and the steering fluid pressure pump driving means by a signal 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 distributes the driving means. The discharge side of the steering operation fluid pressure pump is preferentially communicated with the steering flow path side via the steering wheel, 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 based on the signal from the control unit, the steering hydraulic pump driving unit is driven, and the discharge side of the steering hydraulic pump is connected to the steering flow path side via the distribution unit. Only to
When it is determined that there is no steering operation and that 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,
When the discharge side of the steering operation fluid pressure pump is connected to the bypass flow path side via the distribution unit, and it is determined that there is no steering operation and there is no cargo operation based on signals from the steering operation detection unit and the cargo operation detection unit. Is characterized in that the steering fluid pressure pump driving means is stopped.

In the case where the bypass flow path is branched from the steering flow path and an on-off valve constituting a distribution means is provided in the middle of the bypass flow path, 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 for connecting the steering flow path and a cylinder portion of a power steering as a steering circuit.

A priority valve is interposed in the steering flow path at a position closer to the steering operation fluid pressure pump than the steering control valve which communicates the steering flow path with the cylinder portion of the power steering as a steering circuit. And
And, it may communicate the surplus flow volume delivery port of the priority valve to the cargo handling circuit.

[0012]

The working fluid from the steering hydraulic pump can be supplied to the cargo handling circuit by the bypass passage. When the steering operation is not performed, there is no need 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 unit.

[0013] Thus, the supply amount of the working fluid to the cargo handling circuit is increased without increasing the size of the cargo handling fluid pressure pump, thereby improving the cargo handling operation performance when the steering operation is not performed. Further, with the configuration as described in claim 3, when both the steering operation and the cargo handling operation are operated, the fluid pressure sources are independently operated as in the related art,
The working fluid from the steering operation 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 driving means such as a motor and the driving fluid pressure pump is driven 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. Thereby, the cargo handling operation performance is improved, for example, the moving speed of a cargo handling device such as a mast driven by the cargo handling circuit is increased.

When both the steering operation and the cargo handling operation are not performed, the drive of the hydraulic pump is stopped to prevent unnecessary consumption of energy. Further, when an on-off valve constituting the distribution means is provided in the bypass passage, if the on-off valve fails and remains open, the fluid pressure for steering operation is also maintained during steering operation. A part of the working fluid discharged from the pump flows into the cargo-handling hydraulic circuit, so that the supply amount of the working fluid to the steering circuit may be insufficient, and a predetermined power steering function may not be secured.

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

Also, by providing a check valve in the steering flow path, when the steering operation is stopped, that is, when the steering operation fluid pressure pump is stopped, the backflow of the working fluid from the steering circuit is suppressed. , A predetermined residual pressure is secured in the steering circuit.
As a result, the time during which the steering operation fluid pressure pump is driven again until the steering circuit reaches the predetermined set pressure is shortened, and the response of the steering operation is improved.

Further, by adopting a closed center type valve as the steering control valve, when no load is applied, that is, when the steering operation is not performed, the fluid is supplied from the steering operation fluid pressure pump through the steering flow path. The working fluid is not returned 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 for suppressing the return of the working fluid to the tank in the steering flow path.

The flow rate required for the steering system corresponds to the speed at which the operator turns the steering wheel. Generally, the minimum flow rate to be secured 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, which secures the necessary flow rate to the steering system, to the cargo handling circuit side. Thereby, the cargo handling operation performance while performing the steering operation is improved.

[0020]

An embodiment of the present invention will be described with reference to the drawings.
The following embodiment is a 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 oil is used as a fluid will be described. First, the configuration will be described. As shown in FIG. 1, the steering motor 2 is driven and controlled by a battery (not shown) as a power source in accordance with a command from the controller 1, and the steering hydraulic pump 3 is driven by the driving of the steering motor 2. It can be driven. One end of a 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 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 that is switched and controlled via a steering operation device by rotating a steering wheel. Accordingly, a function of supplying hydraulic oil to the first chamber 6a of the power cylinder device 6 to move the piston rod toward the second chamber 6b, and a function of supplying hydraulic oil to the second chamber 6b of the power cylinder device 6 to provide the piston A function of moving the rod toward the first chamber 6a. In the power cylinder device 6, the cylinder device main body is supported on the vehicle body side, and the piston rod is supported on the steering gauge to perform the assisting control of the steering force.

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

The loading control valve 10 is a closed center type 4-port 3-position switching valve that is switched and controlled by a loading lever 11, and the lift cylinder device 12 is operated in accordance with the setting from the loading 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 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.

The bypass passage 13 branches off from the middle of the steering passage 4, and the other end of the bypass passage 13 joins the middle of the cargo handling passage 9. The bypass channel 1
In the middle of 3, an electromagnetic on-off valve 14 and a check valve 14a constituting a distribution means are interposed. The check valve 14
The reference character “a” permits the flow of the hydraulic oil in the bypass flow path 13 to flow only from the steering flow path 4 side to the cargo handling flow path 9 side, and prevents the flow in the opposite direction.

The solenoid on-off valve 14 is actuated by a command from the controller 1 to operate the bypass passage 13.
The flow of hydraulic oil inside can be opened and closed. Further, the steering control valve 5 is provided with a pressure sensing sensor 15 constituting a steering operation detecting means. The pressure sensor 15 detects the presence or absence of a steering operation based on the pressure in the steering control valve 5 and can supply a presence or absence signal to the controller 1.

Further, a microswitch 16 constituting a cargo handling operation detecting means is provided for the cargo handling lever 11. The microswitch 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. Controller 1
The steering motor 2, the cargo handling motor 7, and the electromagnetic on-off valve 14 are controlled in accordance with signals from the pressure sensor 15 and the microswitch 16.

More specifically, when the presence signal is input from the pressure sensor 15 and the presence signal is input from the microswitch 16, the controller 1 determines that the steering operation and the cargo handling operation are to be performed, and A drive signal is supplied to the loading motor 7 and a closing command is transmitted to the electromagnetic on-off valve 14. When the presence signal is input from the pressure 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 transmitted 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 on-off valve 14.

Further, when the absence signal is input from the pressure sensing 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 A drive signal is supplied to the motor 7, and an open command is transmitted to the electromagnetic on-off valve 14. Further, when the absence signal is input from the pressure sensor 15 and the absence signal is input from the microswitch 16,
Judging that 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 on-off valve 14.

In the hydraulic circuit having the above configuration, when the operator rotates the steering wheel, the steering control valve 5 is controlled to be switched to the steering position via the steering operation device. Then, the steering control valve 5
Is switched to the steering operation, the pressure sensing sensor 15
Is detected and the presence signal is supplied 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 down position, if the presence signal is input from the micro switch 16 to the controller 1, the controller 1
Supplies a drive signal to the steering motor 2 and the cargo handling motor 7 and transmits a close command to the electromagnetic on-off valve 14.

As a result, the solenoid on-off valve 14 is operated to the closed position to close the flow of the hydraulic oil in the bypass flow path 13, and the hydraulic oil flowing in the steering flow path 4 flows to the cargo control valve 10. Is blocked. When the steering motor 2 is driven, the steering operation 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 6 b 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 operation hydraulic pump 8 is driven to supply hydraulic fluid to the cargo handling control valve 10 through the cargo handling channel 9, The oil is supplied to the lift cylinder device 12, and the lifting operation of the lift is performed. When the steering control valve 5 is switched to the steering position and the cargo control valve 10 is switched to the neutral position via the steering operation device, the controller 1 inputs a presence signal from the pressure sensor 15. Micro switch 1
6, a closing signal is transmitted to the solenoid on-off valve 14 to keep the flow of the bypass flow path 13 closed, and a stop signal is supplied to the cargo handling motor 7 to supply 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 the driving of 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 by the piston rod of the lift cylinder device 12. In addition, 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 subsequently supplied to the power cylinder device 6 to perform the steering operation.

The steering control valve 5 is controlled to be switched to the neutral position and the cargo control valve 10 is controlled.
Is switched to the cargo-handling position, the controller 1 inputs the absence signal from the pressure sensor 15 and the presence signal from the microswitch 16. Then, the controller 1 transmits an open command to the electromagnetic on-off valve 14 to enable the flow of the hydraulic oil in the bypass passage 13, and supplies a drive signal to the steering motor 2 and the cargo handling motor 7. .

Then, 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 hydraulic pump 3 for steering operation, but is not supplied to the control valve 5 for steering because the steering control valve 5 is set to the neutral position. 13 and is supplied to the cargo control valve 10.

The cargo handling control valve 10 supplies hydraulic oil supplied from both the cargo handling hydraulic pump 8 and the steering hydraulic pump 3 to the lift cylinder device 12 to perform the cargo handling operation. At this time, the supply amount of hydraulic oil per unit time supplied to the cargo handling control valve 10 and the lift cylinder is increased as compared with only the cargo handling hydraulic pump 8, and the speed of lifting and lowering of the lift is lower than before. Is also implemented at a high speed.

The steering control valve 5 is controlled to switch to the neutral position and the cargo control valve 10 is controlled.
Is controlled to be 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 transmits a close command to the electromagnetic on-off valve 14.

Then, the electromagnetic on-off valve 14 is closed, the flow of the hydraulic oil in the bypass passage 13 is blocked, and the steering system and the cargo handling system are separated. In addition, since the cargo handling operation hydraulic pump 8 is stopped and the cargo handling control valve 10 is in the neutral position, the operating oil in the cargo handling flow path 9 flows through the return port of the cargo handling control valve 10. Return to the tank 17.

On the other hand, the steering operation hydraulic pump 3 is also stopped. However, since the steering control valve 5 is of a closed center type, the hydraulic oil in the steering flow path 4 passes through the return port of the steering control valve 5. Is prevented from returning to the tank 17. At this time, since the electromagnetic on-off valve 14 is closed, the operating oil in the steering flow path 4
Does not flow to the cargo handling control valve 10 and the cargo handling operation hydraulic pump 8 side.

As described above, in the hydraulic circuit of the above embodiment,
Without increasing the size of the cargo handling motor 7 and the cargo handling hydraulic pump 8, the lift cylinder device 12 for stopping the steering operation can be used.
The amount of hydraulic oil supplied to the lift is increased, and the lifting speed of the lift can be set higher than before. When the steering operation and the cargo handling operation are not performed, the steering motor 2 and the cargo handling motor 7 are stopped, so that unnecessary energy consumption is suppressed.

In the above embodiment, a closed center type valve is used as the cargo control valve 10, but an open center type valve may be used.
However, as it is, when the hydraulic oil from the steering operation 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 operation hydraulic pump 3 is supplied. Return to the tank 17 via the return port of the steering control valve 5, as shown in FIG. 2, the connection between the bypass flow path 13 branch point in the steering flow path 4 and the input port of the steering control valve 5. When the steering control valve 5 is in the neutral position, the electromagnetic on-off valve 20 is interposed.
It is necessary to control so as to close by operating the.

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

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

With the diaphragm 21 not installed,
If the solenoid on-off valve 14 breaks down and enters a failure mode of a normally open state, at the time of steering operation, hydraulic oil discharged from the steering operation hydraulic pump 3 flows to the cargo handling system via the bypass passage 13. However, the desired hydraulic oil is not secured in the steering system, and the power steering function cannot be exhibited. On the other hand, if the throttle 21 is formed as in the second embodiment, if the steering operation is performed in a state in which the solenoid on-off valve 14 fails and enters the normally open failure mode, the steering operation is performed. A part of the hydraulic oil discharged from the hydraulic pump 3 flows toward the bypass passage 13, but a predetermined fluid pressure is maintained by the throttle 21, and a predetermined fluid pressure for the steering system is secured.

In particular, since the load on the steering operation during traveling is small, it is sufficient to maintain the pressure by the throttle 21.
Deterioration of steering operability during traveling is avoided, and safety is improved. Other functions and effects are the same as 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, if a relief valve is employed as the pressure holding means, the line pressure of the cargo handling circuit must be set to a value higher than the set pressure of the relief valve in order for hydraulic oil to flow to the cargo handling circuit. By setting the line pressure on the cargo handling circuit side higher than the load on 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 the presence or absence of the steering operation. And

Next, a third embodiment will be described. As shown in FIG. 4, the basic configuration of the hydraulic circuit of the third embodiment is the same as that of the first and second embodiments, and a check valve 23 is provided in the middle of the steering flow path 4. Is different. The check valve 23 allows a flow toward the steering control valve 5 and controls the steering operation hydraulic pump 3.
It blocks the flow to the side.

By providing the check valve 23, the steering operation is stopped, that is, the steering control valve 5
Is in the neutral position and when the steering operation hydraulic pump 3 stops, the backflow of hydraulic oil to the steering operation hydraulic pump 3 side is suppressed as much as possible to secure the residual pressure. Thereby, the responsiveness of the steering operation at the time of performing the steering operation next time is improved. Other functions and effects are the same as those of the first and second embodiments.

In FIG. 4, the check valve 23 is interposed between the branch point of the bypass passage 13 and the steering control valve 5. It may be interposed between the branch point. Next, the fourth
An example will be described. The basic configuration of the hydraulic circuit of the fourth embodiment is the same as that of the first and second embodiments, as shown in FIG. 5, except that a priority valve 24 is interposed in the steering flow path 4. Are different.

The priority valve 24 sets the steering circuit as a priority circuit, and connects the surplus flow rate extraction port to the cargo handling flow path 9 via the second bypass flow path 13. In FIG. 5, reference numeral 25 denotes a check valve. With this configuration, when hydraulic oil is supplied from the steering operation hydraulic pump 3 to the steering control valve 5 via the steering flow path 4, the flow rate required in the steering system is controlled by the priority valve 24. And the remaining surplus flow rate can be sent to the cargo handling system via the second bypass passage 13,
Even when the steering operation and the cargo handling operation are simultaneously performed, the working oil is supplied to the cargo handling circuit more than before, and the cargo handling operability is improved.

Other functions and effects are the same as those of the first and second embodiments. In all of the above embodiments, a battery vehicle is described as a cargo-handling vehicle. However, the invention is not limited to a battery-powered vehicle, but may be an engine vehicle, and the steering operation hydraulic pump 3 and the cargo-handling hydraulic pump 8 The present invention is also applicable to vehicles having independently mounted.

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

[0052]

As described above, in the fluid pressure circuit in the cargo handling vehicle of the present invention, the steering operation is performed by effectively utilizing the pressure fluid of the steering system without changing the fluid pressure parts on the cargo handling side. It is possible to improve the cargo handling operation performance in a state where it is not performed. Further, by providing the priority valve, it is possible to improve the cargo handling operation performance without changing the fluid pressure parts on the cargo handling side even during the steering operation.

[Brief description of the 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 operation hydraulic pump 4 Steering passage 5 Steering control valve 6 Power cylinder device 7 Loading motor 8 Loading handling hydraulic pump 9 Loading passage 10 Loading control valve 13 Bypass passage 14 Solenoid on-off valve 15 Pressure sensor 16 Micro switch 21 Throttle 23 Check valve 24 Priority valve

Claims (7)

(57) [Claims] (1) Each of the pump driving means which operates independently is provided with :
Independently comprise a steering operation fluid pressure pump and the hydraulic pump for loading operation as a fluid pressure source to be driven, a steering hydraulic fluid from the steering operation fluid pressure pump via a steering channel Te Supply to the circuit for
In a cargo handling vehicle in which a working fluid from a fluid handling pump can be supplied to a cargo handling circuit via a cargo handling channel, a discharge side of the steering fluid pressure pump communicates with the cargo handling circuit. A bypass passage, and a distribution means for distributing the working fluid discharged from the steering operation fluid pressure pump to the steering passage and the bypass passage, to only one of the passages, or to both of them at a predetermined ratio. And a fluid pressure circuit in the cargo handling vehicle. 2. A hydraulic pump for steering operation as a fluid pressure source.
And a fluid handling pump for cargo handling operation.
The working fluid from the pressure pump is supplied to the steering
Road, and a fluid pressure port for cargo handling
Working fluid from the pump to the cargo handling circuit via the cargo handling channel
In a cargo handling vehicle that can be supplied, the steering operation
That connects the discharge side of the hydraulic pump for
The path discharged from the pump and the fluid discharged from the steering operation fluid pressure pump
The moving fluid is supplied to the steering flow path and the bypass flow path.
Distribute only to one channel or both at a predetermined ratio
And distribution means, in the case of the loading operation without the steering operation, the discharge side of the steering operation fluid pressure pump, via a distribution means, a distribution control means for controlling so as to communicate only with the bypass flow A fluid pressure circuit in a cargo-handling vehicle, comprising: 3. A steering operation detecting means for detecting the presence or absence of a steering operation, a cargo handling operation detecting means for detecting the presence or absence of a cargo handling operation, a steering hydraulic pump driving means for driving a steering hydraulic pump, and a steering operation. Detection means, cargo handling operation detection means,
A controller connected to the distributing means and the steering fluid pressure pump driving means, and controlling the distribution 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 from the signals from the steering operation detecting means and the cargo handling operation detecting means that the steering operation has been performed and the cargo handling operation has been performed, the controller drives the steering fluid pressure pump driving means and performs the steering operation via the distribution means. When the discharge side of the hydraulic pump for communication is preferentially communicated with the steering flow path side, and when it is determined that there is a steering operation and there is no cargo handling operation by a signal from the steering operation detecting means and the cargo handling operation detecting means, The steering fluid pressure pump driving means is driven, and the discharge side of the steering fluid pressure pump is connected to only the steering flow path side via the distribution means. When it is determined from the signals from the steering operation detecting means and the cargo handling operation detecting means that there is no steering operation and that there is a cargo handling operation, the steering fluid pressure pump driving means is driven, and the steering operation fluid is distributed via the distribution means. The discharge side of the pressure pump communicates with the bypass flow path side,
2. The cargo handling vehicle according to claim 1, wherein when it is determined from the signals from the steering operation detection means and the cargo handling operation detection means that there is no steering operation and no cargo handling operation, the steering fluid pressure pump driving means is stopped. The hydraulic circuit in. 4. When a bypass passage is branched from a steering passage and an on-off valve constituting distribution means is provided in the middle of the bypass passage, a pressure holding means is interposed in the bypass passage. The fluid pressure circuit in a cargo handling vehicle according to any one of claims 1 to 3, wherein: 5. The fluid pressure circuit in a cargo handling vehicle according to claim 1, wherein a check valve is interposed in the steering passage. 6. A closed center type valve is used as a steering control valve for connecting a steering passage 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 the above. 7. A priority valve is interposed in a steering flow path at a position closer to a steering operation fluid pressure pump than a steering control valve that communicates a steering flow path with a cylinder portion of a power steering as a steering circuit. and, and, a fluid pressure circuit in cargo handling vehicle as claimed in any one of claims 1 to 6, characterized in that communicating with the surplus flow volume delivery port of the priority valve to the cargo handling circuit.