JPH07315793A - Fluid pressure circuit in cargo handling vehicle - Google Patents

Abstract

PURPOSE:To improve energy efficiency when an attachment is operated. CONSTITUTION:A steering oil hydraulic pump 3 is connected through a steering flow path 4 to a steering control valve 7. A priority valve 11 is interposed in the steering flow path 4. A bypass flow path 12 is connected to a surplus flow take out port of the priority valve 11. The other end part of the bypass flow path 12 is connected to an attachment use control valve 16. Pressure detecting sensors 40, 41 are respectively provided in the steering control valve 7 and the attachment use control valve 16. In a controller 1, in accordance with a signal from each pressure detecting sensor 40, 41, a steering motor 2 is controlled.

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 pressure for steering is changed by switching the solenoid valve or the like. Some pumps are configured to preferentially supply the working fluid from the pump 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 heavier, a larger output is used as the drive means for driving the fluid pressure source compared to the configuration that supplies the working fluid from the fluid pressure source 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 drive motor and the fluid pressure pump to supply the fluid pressure, and the energy efficiency is not good.

For this reason, it is not possible to cope with a vehicle in which energy consumption is desired to be suppressed as much as possible, for example, a battery vehicle driven by a storage battery mounted on the vehicle body. 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]

As described above, since the load of the cargo handling operation is larger than the load of the steering operation, the cargo handling motor and the cargo handling pump are larger than the steering operation motor and the steering pump. A large output is used. However, although the attachment operation of the cargo handling operation has a small cargo handling load, in the fluid pressure circuit in the conventional cargo handling vehicle as described above, the attachment is driven by the high power cargo handling motor or cargo handling pump. . Therefore, there are problems that energy efficiency is low and current consumption is large.

The present invention has been made in view of the above problems, and an object thereof is to improve the energy efficiency during the operation of the attachment.

[0008]

In order to achieve the above object, a fluid pressure circuit in a cargo handling vehicle according to a first aspect of the present invention includes a steering fluid pressure pump and a cargo handling fluid pressure as fluid pressure sources. With a pump, the working fluid from the steering fluid pressure pump can be supplied to the steering circuit via the steering passage, and the working fluid from the cargo handling fluid pump flows through the cargo handling passage. In the cargo handling vehicle that can be supplied to the cargo handling circuit via the cargo handling circuit, the attachment operating circuit of the cargo handling circuit is not in communication with the cargo handling fluid pressure pump, and the discharge side of the steering fluid pressure pump. And a bypass flow path communicating with the attachment operation circuit, and a working fluid discharged from the steering fluid pressure pump, with respect to the steering flow path and the bypass flow path, in only one of the flow paths or a predetermined flow path. And distribution means for distributing to both at the rate,
It is characterized by having.

At this time, as described in claim 2, when the attachment is operated without the steering operation, the discharge side of the steering fluid pressure pump is connected to the bypass flow path side through the distribution means. It is characterized in that a distribution control means for controlling so as to communicate with is provided. Further, in each of the above inventions, as described in claim 3, a steering operation detecting means for detecting the presence or absence of a steering operation, an attachment operation detecting means for detecting the presence or absence of an attachment operation,
Via a steering fluid pressure pump drive means for driving the steering fluid pressure pump, a controller for controlling the steering fluid pressure pump drive means by signals from the steering operation detection means and the attachment operation detection means, and a distribution means. ,
When the steering operation is being performed, the discharge side of the steering fluid pressure pump is preferentially communicated with the steering flow path side, and when the steering operation is not operated and the attachment is operated, the discharge side of the steering fluid pressure pump is bypassed. Distribution controller that preferentially communicates with the roadside, and the controller is configured to perform steering operation when it determines that there is a steering operation or an attachment operation based on signals from the steering operation detection means and the attachment operation detection means. The driving fluid pressure pump driving means is driven, and when it is determined that there is no steering operation and no attachment operation, the steering fluid pressure pump driving means is stopped.

Further, in each of the above inventions, as described in claim 4, a priority valve constituting a distributing means is provided in the steering flow path, and the surplus outflow port of the priority valve is provided. A control valve for steering, which communicates the steering passage with the cylinder portion of the power steering as the steering circuit, and the bypass passage and the actuator for attachment. It is characterized in that each of the attachment control valves communicating with and is a closed center type valve.

At this time, as described in claim 5, a pressure holding means is provided in the bypass passage. Further, in addition to the invention described in claim 1, claim 2 or claim 3, as described in claim 6, the bypass channel is branched from the steering channel,
An on-off valve that constitutes a distribution means is provided in the bypass flow passage, and a pressure holding means is provided in the bypass flow passage.

[0012]

The bypass flow path allows the working fluid from the steering fluid pressure pump to be supplied to the attachment operating circuit. As a result, the steering fluid pressure pump can drive the attachment operation, which is a relatively light load of the cargo handling operation.

As described in claim 2, when the steering operation is not performed, it is not necessary to supply the working fluid to the steering circuit side. Therefore, the steering fluid pressure pump from the steering fluid pressure pump is supplied through the distribution means. Supply working fluid to the attachment operation circuit side. With this, the attachment is
It is driven by a steering fluid pressure pump and a steering drive means that have smaller outputs than those for cargo handling. Therefore, the energy consumption efficiency required for driving the attachment is improved.
At this time, the working fluid from the discharge side of the steering fluid pressure pump is preferentially supplied to the attachment operation circuit side via the bypass flow passage, so that a sufficient fluid pressure for driving the attachment can be secured. Become.

Further, with the configuration as described in claim 3, the presence or absence of the steering operation and the attachment operation is detected by the steering operation detection means and the attachment operation detection means, respectively, and the steering operation is detected by the controller. The steering fluid pressure pump is driven only when it is determined that at least one of the attachment operations is operated.

Thus, the steering fluid pressure pump is driven not only during the steering operation but also during the attachment operation, and the working fluid can be supplied from the steering fluid pressure pump to the attachment operation circuit. In addition, the distribution control means preferentially communicates the discharge side of the steering fluid pressure pump with the steering flow path side when the steering operation is performed, so that the steering operation can be performed even if the attachment operation is performed. The necessary working fluid is supplied to the steering circuit to ensure a predetermined steering performance.

While the steering operation is being performed, the working fluid is preferentially supplied to the steering circuit side, so that only the surplus flow rate is supplied to the attachment operation circuit side. . As a result, the operating speed of the attachment is kept low while the vehicle is being steered. In addition, the distribution control means preferentially supplies the working fluid discharged from the steering fluid pressure pump to the attachment operating circuit via the bypass flow path when the steering operation is not in operation and the attachment is operated. . Therefore, when the steering operation is not performed, the attachment can be driven with the performance such as the operating speed similar to the conventional one.

When neither the steering operation nor the attachment operation is performed, driving of the fluid pressure pump is stopped to prevent unnecessary energy consumption. For example, as described in claim 4, by providing the priority valve, it is possible to supply the remaining surplus flow rate that secures the necessary flow rate preferentially to the steering circuit side to the attachment operation circuit side. Become. This enables the attachment operation while performing the steering operation.

In this case, only the excess flow rate flows through the attachment, and the operation speed of the attachment while steering becomes slow. Further, by using the closed center type valves of the steering control valve and the attachment control valve, the port of each control valve is set to the closed state when the steering operation or the attachment operation is not operated.

Therefore, for example, when the steering operation is not operated, the fluid pressure in the steering circuit is sealed at a predetermined value, and the piston position of the cylinder device of the power steering is immediately after the earliest operation. Retained. Similarly, even when the attachment operation is not performed, the fluid pressure in the attachment circuit is sealed at a predetermined value, and the position of the attachment is maintained in the state immediately after the earliest operation.

Further, the working fluid discharged from the steering fluid pressure pump is prevented from returning from each control valve to the working fluid tank. When an open center type valve is used as the control valve, it is necessary to separately provide an opening / closing valve or the like for suppressing the circulation of the working fluid in the steering flow passage and the bypass flow passage when each operation is not performed.

The flow rate required for the steering system corresponds to the speed at which the steering wheel is turned by the operator, and generally, the minimum flow rate to be ensured has been known at the time of design. Therefore, by providing the priority valve, it becomes possible to supply the remaining surplus flow rate that secures the necessary flow rate preferentially to the steering system to the attachment operation circuit side. This improves the attachment operation performance while performing the steering operation.

Further, as described in claim 5, by providing the pressure holding means in the bypass flow passage, when the steering operation is carried out in the non-operation state of the attachment operation, the surplus flow is supplied to the bypass flow passage side to cause the bypass flow. A predetermined set pressure is set in the flow path. Therefore, the responsiveness is improved when the attachment operation is performed in this state. Further, when a throttle is provided as the pressure holding means, even if the attachment control valve fails in the normally open state, the fluid pressure in the bypass flow passage is held at a predetermined pressure, and thus the steering circuit is And a predetermined fluid pressure is secured.

As a result, even if the attachment control valve fails in the normally open state while the vehicle is traveling, a predetermined power steering pressure is ensured and traveling safety is guaranteed. In addition, for example, it is configured as described in claim 6. In this case, an opening / closing valve is provided as a distributing means, and the opening / closing operation of the opening / closing valve distributes and supplies the working fluid supplied to the steering passage to the bypass passage.

At this time, by providing a pressure holding means such as a throttle 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.
Therefore, a predetermined fluid pressure is secured for the steering circuit. As a result, a predetermined power steering pressure is secured even if the attachment control valve fails in the normally open state while the vehicle is traveling, and traveling safety is guaranteed.

[0025]

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,
A case where hydraulic oil is used as the working fluid will be described. First, the configuration will be described. As shown in FIG.
The steering motor 2 is drive-controlled by a command (1) from a battery (not shown) as a power source, and the steering hydraulic pump 3 can be driven by driving the steering motor 2. One end of the steering flow path 4 is connected to the discharge side of the steering hydraulic pump 3, and the other end of the steering flow path 4 forms a steering circuit together with the power cylinder device 6 via a check valve 5. It is connected to the input port of the steering control valve 7 that constitutes it. The check valve 5 is
The flow is allowed to the control valve 7 for steering and is blocked to the hydraulic pump 3 for steering.

The return port of the steering control valve 7 communicates with the hydraulic oil tank 9 via the steering return passage 8. Steering control valve 7
Is a closed center type 4-port 3-position switching valve whose switching is controlled via the steering operation device when the steering wheel is rotated. According to the setting from the steering operation device, the power cylinder device 6 A function of supplying hydraulic oil to the first chamber 6a to move the piston rod to the first chamber 6b side, and a function of supplying hydraulic oil to the first chamber 6b of the power cylinder device 6 to move the piston rod to the first chamber 6a side. It has the function to let.

In the power cylinder device 6, the main body of the cylinder device is supported on the vehicle body side, and the piston rod is supported by the steering gauge to control assisting the steering force. Further, the steering flow path 4 branches from a position downstream of the check valve 5 insertion position, and a branch path
The inlet port of the relief valve 10 that constitutes the pressure holding means is connected. The outlet port of the relief valve 10 communicates with the steering return passage 8. The relief valve 10 keeps the pressure in the steering channel 4 below a predetermined set pressure.

On the steering hydraulic pump 3 side of the steering flow path 4, a priority valve 11 constituting a distributing means is provided. The priority extraction port side of the priority valve 11 is connected to the steering control valve 7 side, and the surplus flow extraction port is connected to one end of the bypass flow passage 12. The other end of the bypass flow path 12 is connected via a check valve 13 to an input port of an attachment control valve 16 that constitutes an attachment operation circuit together with an attachment actuator 14. The check valve 13 allows the hydraulic fluid in the bypass passage 12 to flow from the steering passage 4 side to the attachment control valve 1
It allows only the flow toward the 6 side and blocks the flow in the opposite direction.

The return port of the attachment control valve 16 communicates with the hydraulic oil tank 9 through the attachment return passage 17. The attachment control valve 16 is a closed center type 4-port 3-position switching valve that is switch-controlled by an attachment operating lever 18, and supplies hydraulic oil to the attachment actuator 14 according to the setting by the attachment operating lever 18. And has a function of operating the actuator 14.

The bypass flow passage 12 is connected to an inlet port of a relief valve 19 which branches off downstream from the check valve 13 and constitutes pressure holding means. The outlet port of the relief valve 19 communicates with the attachment return passage 17. This relief valve 19
As a result, the pressure in the bypass passage 12 is maintained below a predetermined set pressure.

The set pressure of the relief valve 19 provided in the bypass passage 12 is set lower than the set pressure of the relief valve 10 provided in the steering passage 4. This is because the hydraulic fluid can be supplied from the priority valve 11 to the bypass passage 12 side when the steering is not operated. Further, in the above configuration, the steering control valve 7 and the attachment control valve 1
6. The relief valves 10 and 19 also serve as distribution control means for controlling the priority valve 11 that constitutes the distribution means.

As shown in FIG. 2, the controller 1
The load handling motor 20 is driven and controlled by a command from the battery (not shown) as a power source. By driving the cargo handling motor 20, the cargo handling hydraulic pump 21 can be driven. One end of a cargo handling passage 22 is connected to the discharge side of the cargo handling hydraulic pump 21.
The other end of 2 is branched and is connected to the input port of the lift operation control valve 25 that constitutes the cargo handling circuit together with the lift cylinder device 24, and also constitutes the cargo handling circuit together with the tilt cylinder device 26. , And are connected to the input ports of the tilt control valve 27, respectively.

Control valve 25 for operating the lift
Is a closed center type 4-port 3-position switching valve that is switched and controlled by the lift cargo handling lever 28, and hydraulic oil is supplied to the first chamber 24a of the lift cylinder device 24 in accordance with the setting from the lift cargo handling lever 28. To move the piston rod upward and to supply the hydraulic oil to the second chamber 24b of the lift cylinder device 24 to move the piston rod downward. In the lift cylinder device 24, 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 30 to control the lifting of the fork.

Control valve 27 for tilt operation
Is a closed center type 4-port 3-position switching valve that is switch-controlled by the tilting cargo handling lever 29. In accordance with the setting from the tilting cargo handling lever 29, hydraulic oil is supplied to the first chamber 26a of the tilt cylinder device 26. To move the piston rod upward and to supply the hydraulic oil to the second chamber 26b of the tilt cylinder device 26 to move the piston rod downward. In the tilt cylinder device, the cylinder device body is supported on the vehicle body side, and the upper part of the piston rod is connected to the mast,
Tilt control of the mast is performed.

Further, the steering control valve 7 is provided with a steering pressure detecting sensor 40 constituting a steering operation detecting means. The pressure detection sensor 40 can detect the presence or absence of a steering operation by the pressure in the steering control valve 7 and can supply a presence signal or a absence signal to the controller 1. For example, the pressure detection of the pressure detection sensor 40 is performed by the pressure detection at the port position of the steering control valve 7 that communicates with the power cylinder device 6.

Further, the attachment control valve 16 is also provided with a pressure detecting sensor 41 constituting an attachment operation detecting means. The attachment pressure detection sensor 41 detects the presence or absence of an attachment operation by the pressure in the steering control valve 7 and can supply a presence signal or a non-existence signal to the controller 1.

For example, the pressure detection of the pressure detection sensor 41 is carried out by the pressure detection at the port position of the attachment control valve 16 communicating with the attachment actuator 14 side. In addition, the lift cargo handling lever 28 and the tilt cargo handling lever 2
Micro switches 42, which constitute a cargo handling operation detection means, are attached to each of the nine. Each micro switch 42 detects the operation of each cargo handling lever 28, 29 and outputs a signal corresponding to the presence or absence of a cargo handling operation to the controller 1.
Can be supplied to.

The controller 1 includes each pressure sensor 4
The steering motor 2 and the cargo handling motor 20 are controlled in accordance with signals from 0, 41 and the microswitch 42. More specifically, when the presence signal is input from at least one of the steering pressure detection sensor 40 and the attachment pressure detection sensor 41, the controller 1 determines that at least one of the steering operation and the attachment operation is performed, and the controller 1 performs the steering operation. A drive signal is supplied to the motor 2. Further, if a no signal is input from both the steering pressure sensor 40 or the attachment pressure sensor 41,
Both the steering operation and the attachment operation are determined to be inactive, and a stop signal is supplied to the steering motor 2.

Further, when the presence signal is input from at least one of the both microswitches 42, it is determined that the cargo handling operation is performed, and a drive signal is supplied to the cargo handling motor 20. When a no signal is input from both of the micro switches 42, it is determined that the cargo handling operation is inactive,
A stop signal is supplied to the cargo handling motor 20. In the hydraulic circuit configured as described above, when the operator rotates the steering wheel, the steering control valve 7 is switched to the steering position via the steering operation device. Then, the steering pressure detection sensor 40 detects that the steering control valve 7 is switched to the steering operation, and the pressure detection sensor 40 supplies the controller 1 with a signal. The controller 1 supplies a drive signal to the steering motor 2,
The steering motor 2 is driven.

Then, the steering motor 2 is driven to drive the steering hydraulic pump 3, and the hydraulic oil discharged from the steering hydraulic pump 3 is supplied to the priority valve 11.
Is supplied to. The hydraulic oil supplied to the priority valve 11 is preferentially supplied to the steering flow path 4 via the priority take-out port, and the surplus hydraulic oil is supplied to the bypass flow path 12 via the surplus flow take-out port. It

The hydraulic oil supplied to the steering flow path 4 side is sent to the steering control valve 7 and then from the steering control valve 7 to the first power cylinder device 6.
Alternatively, while being supplied to one of the second chambers, the hydraulic oil in the other chamber returns to the hydraulic oil tank 9 via the steering control valve 7 and the steering return passage 8. by this,
Steering operation is performed.

At this time, the attachment operating lever 18
When is not operated and the attachment is inactive, the attachment control valve 16 is held in the neutral position and all the ports of the attachment control valve 16 are closed. Therefore, from the priority valve 11 to the bypass passage 1
The excess flow supplied to 2 is blocked from flowing into the attachment circuit, returned to the hydraulic oil tank 9 via the relief valve 19, and the relief valve 19 causes the hydraulic pressure in the bypass passage 12 to reach the set pressure. Held in.

As described above, since the priority valve 11 preferentially supplies the hydraulic oil discharged from the steering hydraulic pump 3 to the steering circuit side, a predetermined power steering operability is ensured. Further, when the attachment operating lever is operated while the power steering is being operated, the attachment control valve 16 is switched from the neutral position to the operating position. Then, the bypass flow path 12 and the attachment actuator 14 side are in communication with each other.

As a result, the priority valve 11
The excess hydraulic oil supplied from the bypass flow passage 12 is supplied to the attachment actuator 14 via the attachment control valve 16 and the excess hydraulic oil drives the attachment. At this time,
As described above, the priority valve 11 preferentially supplies the hydraulic oil to the steering circuit, so that a predetermined operability of the power steering is ensured. Further, since the attachment is driven by the surplus flow rate, the operation of the attachment is delayed, which leads to stability when the vehicle turns.

Further, as described above, even if the attachment is not operated, the excess flow is supplied to the bypass flow passage 12 through the priority valve 11 and the bypass flow passage 12 is supplied.
Since the predetermined set pressure is maintained at, the responsiveness of the attachment operation is good. Further, when the steering operation is not performed, the steering control valve 7 is controlled to be switched to the neutral position, and all the ports of the steering control valve 7 are closed.

In this state, the attachment operating lever 1
When 8 is operated, the attachment control valve 16 is switched from the neutral position to the operating position, and the bypass passage 12 and the attachment actuator 14 side are brought into communication with each other. At the same time, the attachment pressure detection sensor 41 detects that the attachment control valve 16 has been switched to the operating position, and the pressure detection sensor supplies a presence signal to the controller 1. The controller 1 supplies a drive signal to the steering motor 2 and the steering motor 2 is driven.

Then, the steering motor 2 is driven to drive the steering hydraulic pump 3, and the hydraulic oil discharged from the steering hydraulic pump 3 is transferred to the priority valve 1
1 is supplied. The hydraulic fluid supplied to the priority valve 11 will be preferentially supplied to the steering flow path 4 via the priority take-out port, and the excess hydraulic oil will be supplied to the bypass flow path 12 via the surplus flow take-out port. And

At this time, since the steering control valve 7 is closed, the hydraulic oil supplied into the steering flow path 4 returns to the hydraulic oil tank 9 via the relief valve 10 and the relief valve By the action of 10, the pressure in the steering channel 4 rises to the set pressure. And
Since the set pressure of the relief valve 10 on the steering flow path 4 side is lower than the set pressure of the relief valve 10 on the bypass flow path 12 side, the hydraulic oil supplied to the priority valve 11 is bypass flow path 12 Supplied to the side.
Further, the hydraulic oil supplied to the bypass flow passage 12 side is
The actuator is supplied to the attachment actuator 14 via the attachment control valve 16, and the attachment actuator 14 is driven, whereby the attachment operates.

When the steering operation is not performed and the attachment operation is not performed, the steering control valve 7 and the attachment control valve 16 are switched to the neutral position, so that the ports of both control valves 7 and 16 are switched. Is closed, the hydraulic pressures in the attachment circuit and the steering circuit are sealed to predetermined values, and the steered wheels and the attachment are held in the immediately preceding state.

Furthermore, by switching both control valves 7 and 16 to the neutral position, the respective pressure detection sensors 40 and 4 attached to both control valves 7 and 16 are controlled.
1 to supply a no signal to the controller 1, respectively.
The controller 1 determines that both the steering operation and the attachment operation are in the non-operation state by inputting the absence signals from both the pressure detection sensors 7 and 16, and supplies a stop signal to the steering motor 2 to cause the steering motor 2 to operate. , And the steering hydraulic pump 3 are stopped.

Further, since the check valve 5 is provided on the steering control valve 7 side of the steering flow path 4, the steering operation is stopped, that is, the steering control valve 7 is in the neutral position and for steering. When the hydraulic pump 3 is stopped, backflow of hydraulic oil to the steering hydraulic pump 3 side is suppressed as much as possible to secure a residual pressure. This improves the responsiveness of the steering operation when the steering operation is performed next.

Similarly, since the check valve 13 is provided on the side of the attachment control valve 16 of the bypass flow path 12, the operation of the attachment is stopped, that is, the attachment control valve 16 is in the neutral position and the steering hydraulic pressure is set. When the pump 3 is stopped, the reverse flow of hydraulic oil to the steering hydraulic pump 3 side is suppressed as much as possible to secure the residual pressure. This improves the responsiveness of the attachment operation when the attachment operation is performed next.

On the other hand, when the lift cargo handling lever 28 is operated and the lift control valve 16 is controlled to switch from the neutral position to the operating position, the micro switch 42 supplies the presence signal to the controller 1. Then, the controller 1 supplies a drive signal to the lift motor, and the cargo handling motor 20 is driven. The cargo handling motor 20 is driven to drive the cargo handling hydraulic pump 21 to supply hydraulic oil to the lift control valve 16 through the cargo handling flow path 22, and the hydraulic oil is further supplied to the lift cylinder device 24. And the lifting operation of the lift is performed.

When the lift control valve 16 is switched to the neutral position, the micro switch 42 supplies the absence signal to the controller 1. When the tilting operation of the mast is not performed, the controller 1 supplies a stop signal to the cargo handling motor 20 to stop the cargo handling hydraulic pump 21. Control valve for lift 1
When 6 is switched to the neutral position, all ports are closed and the position of the piston rod of the lift cylinder device 24 is maintained at the current position.

When the tilt cargo handling lever 29 is operated to control the tilt control valve 16 to be switched from the neutral position to the operating position, the micro switch 42 supplies the presence signal to the controller 1. Then, the controller 1 supplies a drive signal to the tilt motor, and the cargo handling motor 20 is driven. Alternatively, the loading motor 20 is continuously driven.

When the cargo handling motor 20 is driven, the cargo handling hydraulic pump 21 is driven, hydraulic oil is supplied to the tilt control valve 16 through the cargo handling channel 22, and the hydraulic oil is tilted. The mast is tilted by being supplied to the cylinder device. When the tilt control valve 27 is switched to the neutral position,
The absence signal is supplied from the micro switch 42 to the controller 1. When the lifting and lowering operation of the lift is not performed, the controller 1 supplies a stop signal to the cargo handling motor 20 to stop the cargo handling hydraulic pump 21. When the tilt control valve 27 is switched to the neutral position, all ports are closed, and the tilt cylinder device 2
The position of the piston rod 6 is held at the current position.

Further, when the steering operation and the cargo handling operation are not performed, the steering motor 2 and the cargo handling motor 20 are stopped to suppress unnecessary energy consumption. In the above embodiment, the attachment control valve 16
Although a closed center type valve is used for the above, an open center type valve may be used. However, in this case, an electromagnetic opening / closing valve or the like is provided in the bypass flow passage 12,
When the attachment control valve 16 is in the neutral position, it is necessary to operate the electromagnetic on-off valve to control the bypass passage 12 to be closed.

Further, in all the above embodiments, the bypass flow passage 1
Although the check valve 5 is interposed as the pressure maintaining means for the pressure check valve 2, a throttle may be inserted instead of the check valve 5. In particular, since the load of the steering operation during traveling is small, it is possible to avoid deterioration of the steering operability during traveling sufficiently by maintaining the pressure by the throttle, and the safety is improved. However, in order to return the hydraulic oil supplied to the bypass flow passage 12 side to the tank 9 side when the attachment is not operated, the attachment control valve 16 is configured to connect the input port and the return port at the neutral position. Set to be in a state.

Further, in the above embodiment, a torque sensor is attached to the steering shaft instead of the pressure detection sensor as the steering operation detection means, and the torque sensor detects the rotational torque of the steering wheel to determine whether or not the steering operation is performed. You may do it. Further, in the above embodiment, the pressure detecting sensor is used as the attachment operation detecting means, but the micro switch 42 may be used. However, if a pressure sensor is used, the flow rate can be controlled according to the load.

Next, the second embodiment will be described. First
In the embodiment, the priority valve 11 is used as the distribution means.
The second embodiment is an example in which the electromagnetic on-off valve 50 is adopted as the distributing means. In the configuration of the second embodiment, as shown in FIG. 3, the bypass flow passage 12 is branched from the steering flow passage 4 and the downstream side of the bypass flow passage 12 is connected to the inlet port of the attachment control valve 16. There is. An electromagnetic opening / closing valve 50 forming a distributing means is interposed in the bypass flow passage 12, and the electromagnetic opening / closing valve 50 is
Switching is controlled by a signal from the controller 1. That is, the controller 1 also constitutes distribution control means.

Further, a throttle 51 which constitutes a pressure holding means is provided upstream of the position where the electromagnetic opening / closing valve 50 is provided in the bypass passage 12. Further, although the attachment control valve 16 is a closed center type 4-port 3-position switching valve, in the neutral position,
The entrance port and the return port are in communication with each other.

Further, the controller 1 is the controller 1
When a presence signal is input from at least one of the steering pressure detection sensor 40 and the attachment pressure detection sensor 41, the driver determines that at least one of the steering operation and the attachment operation is performed, and outputs a drive signal to the steering motor 2. Supply. Further, when a no signal is input from both the steering pressure detection sensor 40 and the attachment pressure detection sensor 41, it is determined that both the steering operation and the attachment operation are inactive, and a stop signal is supplied to the steering motor 2. .

Further, when the presence signal is input from the steering pressure detection sensor 40, the controller 1 transmits a close command to the electromagnetic on-off valve 50 to close the electromagnetic on-off valve 50. Further, a no-pressure signal is input from the steering pressure detection sensor 40 and the attachment pressure detection sensor 41
When the presence signal is input from, the open command is transmitted to the electromagnetic opening / closing valve 50 to open the electromagnetic opening / closing valve 50. Further, when the absence signal is inputted from the steering pressure detecting sensor 40 and the absence signal is inputted from the attachment pressure detecting sensor 41, a closing command is transmitted to the electromagnetic on-off valve 50 and the electromagnetic on-off valve 5 is transmitted.
0 is closed.

The other structure is the same as that of the first embodiment. In the second embodiment, when the operator rotates the steering wheel, the steering control valve 7 is switched to the steering position via the steering operation device. Then, the steering pressure detection sensor 40 detects that the steering control valve 7 is switched to the steering operation, and the pressure detection sensor 40 supplies the controller 1 with a signal. The controller 1 supplies a drive signal to the steering motor 2 and also transmits a closing command to the electromagnetic opening / closing valve 50, so that the steering motor 2 is driven and the electromagnetic opening / closing valve 50 is closed.

Then, the steering hydraulic pump 3 is driven by driving the steering motor 2. In this state, since the bypass flow passage 12 is closed, all the hydraulic oil discharged from the steering hydraulic pump 3 is supplied to the steering flow passage 4. The hydraulic oil supplied to the steering flow path 4 side is sent to the steering control valve 7, and then from the steering control valve 7 to one of the first and first chambers 6b of the power cylinder device 6. While being supplied, the hydraulic oil in the other chamber returns to the hydraulic oil tank 9 via the steering control valve 7 and the steering return passage 8. As a result, the steering operation is performed. Since the hydraulic oil discharged from the steering hydraulic pump 3 is supplied to the steering circuit side as in the conventional case, a predetermined operability of power steering is ensured.

Further, in the second embodiment, when the steering operation is performed, the electromagnetic on-off valve 50 is closed, so that no hydraulic oil is supplied to the attachment operating circuit, and therefore the attachment is operated. Is set to disabled. It should be noted that when the attachment pressure detection sensor 41 supplies a presence signal to the controller 1 when the steering operation is performed, the electromagnetic opening / closing operation is performed by the controller 1 so that the attachment operation is performed even when the steering operation is performed. The valve 50 may be subjected to on / off control so that a part of the hydraulic fluid discharged from the steering hydraulic pump 3 can be supplied to the attachment operating circuit.

When the steering operation is not performed, the steering control valve 7 is switched to the neutral position and all the ports of the steering control valve 7 are closed. When the attachment operation lever is operated in this state, the attachment control valve 16 is switched from the neutral position to the operating position. Further, the steering pressure detection sensor 40 detects that the attachment control valve 16 is switched to the operation operation, and the pressure detection sensor supplies the controller 1 with a presence signal.

The controller 1 supplies a drive signal to the steering motor 2 and transmits an opening command to the electromagnetic opening / closing valve 50, so that the steering motor 2 is driven and the electromagnetic opening / closing valve 50 is opened. . Then, the steering motor 2 is driven to drive the steering hydraulic pump 3, and the hydraulic fluid discharged from the steering hydraulic pump 3 is supplied to the steering passage 4.

At this time, since the steering control valve 7 is closed, the hydraulic oil supplied into the steering flow passage 4 flows to the bypass flow passage 12 side, and subsequently passes through the attachment control valve 16. Is supplied to the attachment actuator 14, and thus the attachment actuator 14 is driven to operate the attachment 15.

When the steering operation is not performed and the attachment operation is not performed, the ports of both control valves 7 and 16 are closed because both control valves 7 and 16 are switched to the neutral position. Become. Therefore, the hydraulic pressure in the attachment circuit and the steering circuit is sealed to a predetermined value, and the steered wheels and the attachment are held in the immediately preceding state.

Furthermore, by switching both control valves 7 and 16 to the neutral position, the respective pressure detection sensors 40 and 4 attached to both control valves 7 and 16 are controlled.
From 1 to the controller 1, the absence signal is supplied. The controller 1 determines that both the steering operation and the attachment operation are in the non-operation state by inputting a no signal from both pressure detection sensors, and supplies a stop signal to the steering motor 2 to cause the steering motor 2 and the steering motor 2 to operate. When the hydraulic pump 3 for a vehicle is stopped, a closing command is supplied to the electromagnetic opening / closing valve 50 to close the bypass passage 12.

Other functions and effects are similar to those of the first embodiment. In all of the above embodiments, the case where the hydraulic pressure is used as the fluid pressure has been described, but the pneumatic pressure may be used. Further, although all of the above-described embodiments have been described by taking an example of a forklift truck as a cargo handling vehicle, the invention may be applied to other types of forklift trucks and other cargo handling vehicles.

As described above, the present invention is particularly effective when applied to a battery vehicle as a cargo handling vehicle, but is not limited to a battery vehicle, and even if it is an engine vehicle, the steering hydraulic pump 3 and the cargo handling vehicle are used. It is also applicable to a vehicle in which the hydraulic pump 21 is mounted independently.

[0074]

As described above, in the fluid pressure circuit of the cargo handling vehicle according to the present invention, the attachment is driven by the steering pump and the drive device for driving the pump, so that the energy efficiency at the time of driving the attachment is improved. improves. For example, as described in claim 2,
When the steering operation is not performed, it is not necessary to supply the working fluid to the steering circuit side.Therefore, by supplying the working fluid from the steering fluid pressure pump to the attachment operating circuit side, the attachment outputs more than the cargo handling. Is driven by a small steering fluid pressure pump and steering driving means. Therefore, the energy consumption efficiency required for driving the attachment is improved.

At this time, the working fluid from the discharge side of the steering fluid pressure pump is preferentially supplied to the attachment operating circuit side through the bypass flow passage, so that the output is higher than that of the cargo handling type. Even if a small steering fluid pressure pump and steering driving means are used, sufficient fluid pressure for driving the attachment can be secured. Similarly, in the invention as set forth in claim 3, the steering fluid pressure pump is driven not only during the steering operation but also during the attachment operation, and the steering fluid pressure pump transfers the working fluid to the attachment operation circuit. Can be supplied.

At this time, even if the attachment is operated, since the working fluid required for the steering operation is preferentially supplied to the steering circuit, a predetermined steering performance is ensured. Further, when the steering operation is not performed, the attachment can be driven with the performance such as the operating speed similar to the conventional one. For example, as described in claim 4,
By providing the priority valve as the distribution means, it becomes possible to supply the remaining surplus flow rate that secures the necessary flow rate preferentially to the steering circuit side to the attachment operation circuit side. This enables the attachment operation while performing the steering operation.

In this case, only the excess flow rate flows through the attachment, and the operation speed of the attachment while steering is slowed, which leads to vehicle stability during turning of the vehicle. In addition, by using the closed center type valves of the steering control valve and the attachment control valve, the fluid pressure in the steering circuit can be adjusted to the specified value in the non-operated state without providing an on-off valve etc. It is sealed in and kept in the state immediately after the first operation.

Furthermore, the working fluid discharged from the steering fluid pressure pump is prevented from returning from each control valve to the working fluid tank. Moreover, as shown in claim 5,
By providing the pressure holding means in the bypass flow passage, even if the steering operation is performed in the non-operation state of the attachment operation, the excess flow is supplied to the bypass flow passage side and the predetermined set pressure is set in the bypass flow passage. . Therefore, the responsiveness is improved when the attachment operation is performed in this state.

Further, for example, in the invention described in claim 6, an opening / closing valve is provided as the distributing means, and the working fluid supplied to the steering passage is supplied to the bypass passage by the opening / closing operation of the opening / closing valve. By supplying the hydraulic fluid, the working fluid discharged from the steering hydraulic pump can be distributed and supplied to the steering circuit side and the attachment circuit side. At this time, by interposing a pressure holding means such as a throttle in the bypass passage, even if the on-off valve fails in the normally open state while the vehicle is traveling, a predetermined pressure is held in the bypass passage. A certain power steering pressure is ensured and driving safety is guaranteed.

[Brief description of drawings]

FIG. 1 is a diagram showing a steering side in a fluid pressure circuit in a cargo handling vehicle according to an embodiment of the present invention.

FIG. 2 is a diagram showing a cargo handling side in a fluid pressure circuit in a cargo handling vehicle according to an embodiment of the present invention.

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

[Explanation of symbols]

1 Controller 2 Steering Motor 3 Steering Hydraulic Pump 4 Steering Flow Path 5 Check Valve 6 Power Cylinder 7 Steering Control Valve (Steering Operation Detection Means) 9 Hydraulic Oil Tank 10 Relief Valve (Pressure Holding Means) 11 Priority Valve 12 Bypass Flow path 13 Check valve 14 Attachment actuator 15 Attachment 16 Attachment control valve (Attachment operation detection means) 19 Relief valve (Pressure holding means) 20 Cargo handling motor 21 Cargo handling hydraulic pump 22 Cargo handling flow path 40 Steering pressure sensor 41 Pressure sensor for attachment 50 Electromagnetic on-off valve 51 Throttle (pressure holding means)

Claims (6)

[Claims] 1. A steering fluid pressure pump and a cargo handling fluid pressure pump are provided as fluid pressure sources, and working fluid from the steering fluid pressure pump can be supplied to a steering circuit via a steering flow path. In addition, in the cargo handling vehicle in which the working fluid from the cargo handling fluid pressure pump can be supplied to the cargo handling circuit through the cargo handling flow path, the attachment operating circuit of the above cargo handling circuit is used as the cargo handling fluid. A bypass flow path which is in a non-communication state with the pressure pump and which connects the discharge side of the steering fluid pressure pump and the attachment operation circuit,
And a distribution means for distributing the working fluid discharged from the steering fluid pressure pump to the steering passage and the bypass passage only in one of the passages or at a predetermined ratio. A fluid pressure circuit in a characteristic cargo handling vehicle. 2. A distribution control means is provided for controlling the discharge side of the steering fluid pressure pump so as to communicate with the bypass flow passage side via the distribution means when the attachment is operated without steering operation. Claim 1 characterized by the above.
A fluid pressure circuit in a cargo handling vehicle described in. 3. Steering operation detecting means for detecting the presence or absence of a steering operation, attachment operation detecting means for detecting the presence or absence of an attachment operation, steering fluid pressure pump driving means for driving a steering fluid pressure pump, and the above steering. When the steering operation is being performed, a controller for controlling the steering fluid pressure pump drive means by a signal from the operation detection means and the attachment operation detection means, and the discharge side of the steering fluid pressure pump is steered when the steering operation is performed. And a distribution control means for preferentially communicating the discharge side of the steering fluid pressure pump with the bypass flow passage side when the steering operation is not operated and the attachment is operated. There is a steering operation or an attachment operation depending on the signals from the steering operation detecting means and the attachment operation detecting means. If it is determined that the steering fluid pressure pump drive means is driven, and if it is determined that there is no steering operation and no attachment operation, the steering fluid pressure pump drive means is stopped. A fluid pressure circuit in a cargo handling vehicle according to claim 1 or 2. 4. A steering flow path is provided with a priority valve constituting a distribution means, and the excess flow outlet port side of the priority valve is connected to an attachment operating circuit via a bypass flow path, and steering is performed. Closed center type valves are used for the steering control valve that connects the power flow passage and the power steering cylinder as the steering circuit, and for the attachment control valve that connects the bypass flow passage and the attachment actuator. The fluid pressure circuit in the 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 4, wherein a pressure holding means is provided in the bypass flow passage. 6. A bypass flow path is branched from a steering flow path, an opening / closing valve constituting a distribution means is provided in the bypass flow path, and a pressure holding means is interposed in the bypass flow path. A fluid pressure circuit in a cargo handling vehicle according to any one of claims 1, 2 and 3.