JPH072596B2 - Forklift load / push control device - Google Patents

Description

The present invention relates to industrial use of the present invention. By moving a face on a fork claw forward and backward, a load on a slip sheet is pulled up on the fork claw or pushed out from the claw for cargo handling work. The present invention relates to a load push / pull control device for a forklift.

2. Description of the Related Art Among the conventional load push-pull control devices, those that synchronize the forward / backward movement of the face with the forward / backward movement of the vehicle body are disclosed, for example, in Japanese Utility Model Publication No. 58-4599, Japanese Utility Model Publication No. 58-4600, and Japanese Utility Model Publication No. 58-4600. Many are known, such as the Sho 58-7797 publication.

Problems to be Solved by the Invention The hydraulic fluid discharged from the engine-driven pump is shunted to the power steering cylinder side and the control valve side, and when the push-pull cargo handling work is performed at low speed, When comparing the vehicle speed with respect to the engine speed and the discharge rate of the pump driven by the engine, that is, the moving speed of the face by the push-pull cylinder, the vehicle speed unilaterally increases, so the engine speed is usually higher. It is necessary to control the vehicle speed by raising the vehicle speed and braking, and a high level of technology is required for operation. Therefore, the present invention focuses on the fact that steering operation is not basically involved when the push-pull cargo handling work is performed by moving the vehicle body at a low speed, and the hydraulic oil supplied to the power steering cylinder side during the synchronous mode operation. Can be introduced to the push-pull cylinder side,
A load push-pull control device for a forklift capable of performing push-pull cargo handling work and improving operability without increasing the engine speed.

In the forklift equipped with the push-pull device that moves the face forwards and backwards on the forks of the forks by operating the push-pull cylinder by operating the control valve, rotation of the wheels of the forkslift A drive source, and an oil discharger including a pump that rotates normally and reversely in response to normal and reverse rotations of the wheel, and a switching valve that performs switching operation in conjunction with forward and reverse rotations of the pump, and , An automatic controller that controls the flow control valve between the oil discharger and the push-pull cylinder via a controller based on the detection action of the face-movement detector and the vehicle-movement amount detection, and operates the push-pull cylinder. A hydraulic oil which is provided with a control device and which introduces the hydraulic oil supplied to the power steering and the cylinder side into the oil discharger when the automatic control device operates. Supply switching means is provided.

When the automatic control device is operated, the hydraulic oil supply switching means introduces the hydraulic oil supplied to the power steering cylinder side into the oil discharger and supplies it from the oil discharger to the push-pull cylinder.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a vehicle body, 2 is a mast, 3 is a fork, and a face 5 which is moved forward and backward by a push-pull device 4 is arranged on a claw 3a of the fork 3. The push-pull device 4 includes a pantograph-type link mechanism 6 and a push-pull cylinder 7 that extends and retracts the pantograph-type link mechanism 6. Further, a gripper 9 for gripping and releasing an end portion of the slip sheet (not shown) by the operation of the grip cylinder 8 is attached to the lower side portion of the face 5. Push-pull cylinder 7
And the grip cylinder 8 are connected by a parallel circuit. 10 is push / pull cylinder 7, lift cylinder 11,
It is a control valve that operates the tilt cylinder 12, and a push-pull valve 13, a lift valve 14, and a tilt valve 15 are provided for each of them. 16 is a power steering cylinder, 17 is the same switching valve, 18 is a diversion valve that diverts hydraulic oil to the control valve 10 side and the switching valve 17 side,
Reference numeral 19 indicates a pump driven by the engine 20, and reference numeral 21 indicates a reservoir tank. A sequence valve 23 is provided in the hydraulic oil circuit of the push-pull cylinder 7 so that the grip cylinder 8 can be operated to grip a slip sheet (not shown) prior to the backward movement of the face 5 by the push-pull cylinder 7. It is becoming like this. Reference numeral 24 is a flow rate adjusting valve provided in the hydraulic oil circuit of the grip cylinder 8.

Reference numeral 25 denotes an automatic control device of the push-pull device 4 described above, which includes an oil ejector 26 and a flow control valve 29 provided between the oil ejector 26 and the push-pull cylinder 7 and the grip cylinder 8.
Is equipped with. The oil discharger 26 uses a wheel W of the forklift as a drive source, and a pump 27 that rotates normally and reversely in response to forward and reverse rotations of the wheel W, and a switching operation in conjunction with forward and reverse rotations of the pump 27. And a switching valve 28 for switching. This switching valve 28
When the vehicle body 1 moves forward, the hydraulic fluid discharged from the pump 27 is pushed to the pull side of the push-pull cylinder 7, and when the vehicle body 1 moves backward, the hydraulic fluid discharged from the pump 27 is pushed to the push-pull cylinder 7.
It is designed to switch and supply to the push side of the. The drive of the pump 27 is controlled by the electromagnetic clutch 32 which is operated via the controller 31 by the operation of the synchronous operation switch 30. The flow rate control valve 29 is a vehicle body movement amount detector 33 that detects the amount of movement of the vehicle body 1 based on the amount of rotation of the wheels W.
And the face movement amount detector 34 for detecting the movement amount of the face 5 by the extension and contraction amount of the pantograph type link mechanism 6, the opening and closing control is performed through the controller 31 to control the vehicle body 1. When the movement of the face 5 is too fast with respect to the movement, the flow control valve 29 is opened to relieve a part of the hydraulic oil, and the movement of the face 5 is synchronized with the movement of the vehicle body 1. In this embodiment, the switching valve 28 of the oil discharger 26 described above is connected to and connected to the hydraulic oil carry-over circuit 22 of the control valve 10 so that the hydraulic oil that has carried over from the control valve 10 is supplied to the oil feeder 26. In this way, the correction operation by the control valve 10 can be prioritized as will be described later. Reference numeral 35 denotes a hydraulic oil supply switching means for introducing hydraulic oil supplied to the power steering cylinder 16 side to the oil discharger 26 when the automatic control device 35 is operated, and in this embodiment, a control valve for the shunt valve 18 downstream. The bypass passage 36 is connected to the branch passage 18a on the side, and the bypass passage 36 is connected to the branch passage 18b on the side of the power steering cylinder downstream of the flow dividing valve 18 via the switching valve 37 operated by the operation of the synchronous operation switch 30.
Is connected to the hydraulic oil supply switching means 35.

According to the apparatus of the above embodiment, when the synchronous operation switch 30 is turned on, the switching valve 37 is switched through the controller 31, and the branch passage 18b and the bypass passage 36 communicate with each other.
The entire amount of hydraulic oil discharged from the pump 19 is introduced into the oil discharger 26. Simultaneously with the switching operation of the switching valve 37, the electromagnetic clutch 32 is connected via the controller 31, and the power transmission system with the wheel W of the pump 27 of the oil discharger 26 is continued. When the car body 1 moves forward slowly to take in luggage,
The pump 27 rotates in the normal direction as the wheel W moves in the normal direction, and at the same time, the switching valve 28 switches from the neutral position to the pull side to supply hydraulic oil to the pull side of the push-pull cylinder 7.
The sequence valve 23 supplies hydraulic oil to the grip cylinder 8 earlier than the pull operation of the push-pull cylinder 7, and the gripper 9 grips the end of the slip seat (not shown), and at the same time the push-pull cylinder 7 pulls. To move Face 5 backwards. Therefore, when the vehicle body 1 moves forward,
Due to the pulling operation of the load by the push-pull device 4, the load is taken in on the claw 3a of the fork 3 in a fixed position.
Here, since the push-pull cylinder 7 is a single rod,
The volume of the pull-side oil chamber is smaller than the volume of the push-side oil chamber, and the pull operation is faster than the push operation due to the amount of hydraulic oil supplied from the oil discharger 26. Although the reverse movement of 5 tends to be quicker, the vehicle body movement amount detector 33 and the face movement amount detector 34
This deviation is detected promptly, the flow control valve 29 is opened via the controller 31 and a part of the hydraulic oil is relieved, and the forward movement of the vehicle body 1 and the backward movement of the face 5, that is, the pulling operation of the load, is performed. Is kept in sync. When the vehicle body 1 is retracted at the time of unloading, the hydraulic oil is supplied to the grip cylinder 8 by the reverse rotation of the pump 27 of the oil discharger 26 and the push-side switching of the switching valve 28.
Is supplied to the push-side of the push-pull cylinder 7, the face 5 is moved forward simultaneously with the release of the slip sheet by the gripper 9, and the load is dropped from the claw 3a of the fork 3 in the fixed position. During the cargo handling work by this synchronous mode operation, since the vehicle body 1 slowly moves forward or backward at a low speed, steering operation is almost unnecessary, and accordingly, the operation oil to the switching valve 17 side of the power steering cylinder 16 is not required. If the supply is cut, it will not cause any problems. Rather, since the entire amount of hydraulic oil discharged from the pump 19 can be used for cargo handling, push-pull cargo handling operation can be performed without significantly increasing the engine speed. In other words, the brake control of the vehicle speed accompanying the increase of the engine speed becomes unnecessary, and the operability can be improved accordingly. On the other hand, when the control valve 10 is manually operated during such a synchronous mode operation, the hydraulic oil carry-over circuit 22 of the control valve 10 is cut off, and the hydraulic oil supply to the oil discharger 26 is cut off. The automatic control of is quickly stopped and the control valve 10 is prioritized for manual operation. Accordingly, the tilt cylinder 12 is operated by operating the tilt valve 15 to correct the angle of the mast 2, and the lift cylinder 11 is operated by operating the lift valve 14 to correct the vertical position of the fork 3. You can Further, by operating the push-pull valve 13, the push-pull operation and pull operation of the push-pull device 4 can be corrected, and the postures of the forks 3 and faces 5 can be appropriately corrected to improve the cargo handling work efficiency. . When the correction operation of these is completed, the hydraulic oil carry-over circuit 22 is opened, and it is possible to immediately return to the synchronous mode operation by automatic control.

FIG. 2 shows a different example of the hydraulic oil supply switching means. In this embodiment, in addition to the shunt valve 18, another shunt valve 38
Of the branch valve 38b of the branch valve 38b
While connecting to the steering cylinder side branch passage 18b of 8, the other branch passage 38a is connected to the control valve side branch passage 18a of the flow dividing valve 18, and the front flow passage of the flow dividing valve 38 is the same as in the above embodiment. It is connected to a hydraulic oil passage between the pump 19 and the flow dividing valve 19 via the switching valve 37. The diversion valve 38 has a larger throttle amount than the diversion valve 18 and is set to have a small amount of hydraulic oil supplied to the power steering cylinder 16 side. According to this embodiment, when the synchronous operation switch 30 is turned on and the automatic control device 25 operates in the synchronous mode, most of the hydraulic oil discharged from the pump 19 is transferred from the flow dividing valve 38 to the control valve 10. Although supplied to the discharger 26, a part of the discharge hydraulic oil amount is also supplied from the flow dividing valve 38 to the switching valve 17 side of the power steering cylinder 16. Therefore, when the switching valve 17 is operated by operating the steering wheel in an emergency, the hydraulic oil is immediately supplied to the power steering cylinder 16, and the steering operation can be performed in an emergency and safety measures can be taken.

In any of the above embodiments, the oil discharger 26 is connected to the hydraulic oil carryover circuit 22 of the control valve 10,
By connecting the oil discharger 26 to the control valve, the correction operation can be prioritized over the synchronous mode operation.
The synchronous mode operation and the correction operation can be performed in parallel by connecting to 10 hydraulic oil supply side passages.

As described above, according to the present invention, when the push-pull device that requires almost no steering operation is operated in the synchronous mode,
Since the hydraulic oil supplied to the power steering cylinder side can also be effectively used for cargo handling, the required amount of hydraulic oil can be secured without increasing the engine speed.
Brake control of the vehicle speed is no longer required as the engine speed increases, and operability can be significantly improved. Further, the automatic control device uses an oil discharger that operates by using the rotation of the wheels of the forklift as a drive source, so that the wheels rotate forward and backward, and the push / push cylinder push / push
It is easy to synchronize with the pull operation, that is, to synchronize the longitudinal movement of the vehicle body with the push-pull operation of the push-pull device,
This has a practically great effect that safer cargo handling work can be performed.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the device of the present invention, and FIG.
The drawing is a hydraulic circuit diagram showing a different example of the present invention. 1 ... Car body, 3 ... Fork, 3a ... Claw, 4 ... Push-pull device, 5 ... Face, 7 ... Push-pull cylinder, 10 ... Control valve, 16 ... Power steering cylinder, 25 ...... Automatic control device, 26 …… Oil discharge device, 27 …… Pump, 28 …… Switching valve, 29 …… Flow control valve, 31 …… Controller, 33 …… Vehicle movement amount detector, 34
...... Face movement amount detector, 35 …… Operating oil supply switching means, W …… Wheels.

Claims (1)

[Claims] 1. A forklift equipped with a push-pull device for operating a push-pull cylinder by operating a control valve to move a face forward and backward on a fork claw. As an oil discharger including a pump that rotates forward and backward in response to forward and backward rotation of the wheel, and a switching valve that performs switching operation in conjunction with forward and reverse rotation of the pump, and a face Based on the detection functions of the movement amount detector and the vehicle body movement amount detector, the oil ejector and push
An automatic control device for controlling the flow control valve with the pull cylinder and operating the push-pull cylinder is also provided, and the operating oil supplied to the power steering cylinder side when the automatic control device is operated is the oil. A forklift load push-pull control device comprising a hydraulic oil supply switching means to be introduced into a discharger.