JPH075267B2 - Hydraulic actuator controller for child lift in parent-child forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a lift member of a forklift body (hereinafter referred to as a parent lift) corresponding to a parent lift, and a child lift (hereinafter referred to as a remote control pallet truck) ,
The present invention relates to a parent-child forklift that is detachably equipped with a child lift), and more specifically, to a control device for each hydraulic actuator that is provided on the child lift side as a drive source for traveling, steering, and lifting.

(Prior Art) The parent-child type forklift as described above is used when loading and unloading a transportation container, and as such a parent-child type forklift, some forms have been conventionally used. Are known (see, for example, JP-A-51-85153 or JP-A-55-7181). Generally, a parent-child forklift truck is as shown in the schematic view of FIG. That is, the child lift 4 is hooked on a lift bracket 3 as an ascending / descending member which is guided to move up and down by a mast 2 of a parent lift shown in FIG. 4, the main body 6 side is provided with drive wheels 7 using an oil motor as a drive source, and the leg 8 side corresponding to a fork is provided with auxiliary wheels 9. Further, the child lift 4 is provided with an oil motor for rotationally driving the drive wheels 7, a power steering cylinder for steering the drive wheels 7, and a hydraulic actuator such as a lift cylinder for moving the legs 8 up and down. It is equipped with a lifting function for cargo handling, a traveling function, and a steering function. By operating these functions, the child lift 4 is moved into the container 10 to load and unload the cargo W from the container 10 as shown in the figure.

On the other hand, the piping for the hydraulic actuator is provided with three sets of hose reels 11 on the parent lift 1 side, and two hoses 12 for supply and one for return connected to each actuator by the hose reel 11 are wound. The hydraulic oil supply / discharge control for each hydraulic actuator is performed with the hose reel 11 on the parent lift 1 side.
This is done by switching the electromagnetically operated directional control valve provided in the pipe connecting the hydraulic circuit and the hydraulic unit. That is, the conventional control device is provided with an electromagnetically operated directional control valve 14 for controlling the flow of hydraulic oil supplied from the hydraulic unit 13 on the parent lift side, as shown in the block diagram of FIG.
By switching the direction switching valve 14, the traveling oil motor 15, which is a hydraulic actuator, the power steering cylinder 16 for steering, and the lift cylinder 17 for raising and lowering are individually operated. The solid line in FIG. 5 indicates the hydraulic oil supply system, and the broken line indicates the return system.

(Problems to be Solved by the Invention) However, in the case of the above-mentioned conventional parent-child type forklift, since six hoses are used for the pipe between the parent lift and the child lift, a hose, a hose reel, etc. In addition to the frequent occurrence of failures in the piping components, the front field of view deteriorates, and when switching the electromagnetically operated directional control valve, the entire amount of hydraulic oil is intensively supplied to one hydraulic actuator. Is also likely to occur, and it is difficult to obtain a minute movement.

Therefore, in view of the above problems, the present invention provides a hydraulic actuator control device for a child lift, which can reduce the number of pipes between the parent lift and the child lift and can obtain a smooth operation of the child lift. , And its purpose.

(Means for Solving Problems) The present invention for solving the above problems includes a removable child lift for a lifting member of a parent lift, and the child lift is a hydraulic actuator for traveling, steering, and cargo handling. In a parent-child forklift equipped with, the hydraulic oil is divided into a certain amount of preferential flow and surplus flow on the child lift side in the pipe line connecting the hydraulic unit on the parent lift side and the hydraulic actuator on the child lift side. A flow divider is provided, a steering hydraulic actuator is provided on the priority flow dividing side of the flow divider, and a traveling hydraulic actuator is provided on the surplus flow dividing side.
The gist is that a lifting hydraulic actuator is provided on either the priority flow dividing side or the surplus flow dividing side, and an electromagnetically operated directional control valve is provided between the flow divider and each hydraulic actuator.

(Operation) According to the control device of the present invention configured as described above, the hydraulic oil from the hydraulic unit on the parent lift side passes through the flow divider on the child lift side, and is an electromagnetically operated directional control valve for each actuator. The hydraulic actuator is operated by switching the direction switching valve.
It is possible to obtain the operations of raising and lowering the child lift, traveling, and steering. Therefore, the piping between the parent lift side and the child lift side has a hose for supplying hydraulic oil that connects the hydraulic unit and the flow divider, and a return hose that returns the return oil of each hydraulic actuator to the tank of the hydraulic unit. In addition to this, only one cable is wired for power supply to the electromagnetically operated directional control valve. Further, in operating the child lift, since the hydraulic oil is supplied to each hydraulic actuator in a form of being divided by the flow divider, a smooth start with less shock can be obtained when the direction switching valve is switched.

(Example) Hereinafter, the Example of this invention is concretely described based on drawing. Since the mechanical parts of the forklift main body as the parent lift 1 and the remote control pallet truck as the child lift 2 that is attached to and detached from the parent and child type forklift have the same configuration as conventional ones, the description thereof will be omitted. A control device for each hydraulic actuator mounted on the lift 2 will be described. FIG. 1 is a hydraulic circuit diagram for controlling each hydraulic actuator mounted on the child lift, and FIG. 2 is a block diagram thereof. In the figure, 18 is a flow divider provided on the child lift side, and the hydraulic oil supplied from the hydraulic unit 31 side of the parent lift 1 by this flow divider 18 has a certain amount of preferential flow and excess flow. The power steering cylinder 19 which is a steering drive source and the lift cylinder 20 which is a lifting drive source are installed in parallel on the priority flow side, and on the surplus flow side. An oil motor 21, which is a travel drive source, is installed. In addition, specifically, it is set so that, for example, 5 l / min of hydraulic oil flows on the priority flow side.

The hydraulic oil supply line 22 that connects the flow divider 18 and the cylinders 19 and 20 is provided with two series of electromagnetically operated directional control valves 23 and 24, and these directional control valves 23 and 24 are both 3-position type. The switching operation allows both cylinders 19 and 20 to be operated simultaneously, and is always held at the central position as the neutral position, and communicates with the return pipe 25 at that position. Reference numeral 26 is a choke valve for operating speed control provided at the entrance and exit of the power steering cylinder 19, and 27 is a pilot operated check valve provided to limit the descending speed of the lift cylinder 20.

On the other hand, in the hydraulic oil supply line 28 that connects the flow divider 18 and the oil motor 21, there is a three-position electromagnetically operated directional control valve 29.
Is provided, and the directional control valve 29 is
The flow direction of the hydraulic oil is switched to change the rotation direction (traveling direction), but it is always held at the central position as the neutral position, and at this position, the hydraulic oil supply pipe line 28 and the return pipe line 25 are held.
And communicate with. A brake valve 30 is interposed between the direction switching valve 29 and the oil motor 21, and holds the oil motor 21 in a stopped state in the neutral state of the direction switching valve 29.

The control device that controls each hydraulic actuator on the child lift side is configured as described above, and therefore the piping between the parent lift and the child lift is for guiding the hydraulic oil from the hydraulic unit 31 to the flow divider 18. There are two supply hoses 12a and a return hose 12b for returning the return oil to the hydraulic unit 31, and these two hoses 12a, 12b are installed on the parent lift side as in the conventional case. It is wound up in 11. Although not shown, the power supply cables for the electromagnetically operated directional control valves 23, 24, 29 for operating the hydraulic actuators are also configured to be guided by the cable reels provided on the parent lift side in the same manner as the hoses. It
Further, in FIG. 2, the solid line indicates the hydraulic oil supply system, and the broken line indicates the return system.

The present embodiment is configured as described above, and therefore the hydraulic oil sent from the hydraulic unit 31 of the parent lift is diverted by the flow divider 18 for steering and lifting, and for traveling, so the directional control valve By switching 23, 24 and 29 as appropriate and operating the power steering cylinder 19, lift cylinder 20 or oil motor 21, the child lift can be operated independently of the parent lift to load and unload the container. it can. During this operation, the maximum supply amount of hydraulic oil from the hydraulic unit 31 is, for example, 40
If it is set to about l / min and about 10 l / min when the engine is idle, the flow divider 18 keeps a constant amount (about 5 l
/ min) hydraulic oil is sent, so a stable operating speed can be obtained. Also, since the remaining surplus oil is sent to the running side, the hydraulic oil supplied to the running system will change within the range of 5 to 35 l / min, and therefore an appropriate running speed can be obtained by the accelerator control of the engine. Of course,
In particular, since the excess hydraulic oil is only sent during idle operation, unlike the conventional method of supplying the entire amount of hydraulic oil to the oil motor, a smooth start operation without shock can be obtained.

In this embodiment, a lift cylinder 20 for lifting and lowering is provided to the priority flow dividing side for supplying a fixed amount of hydraulic oil by the flow divider 18.
The lift cylinder for lifting and lowering
As shown in the block diagram of FIG. 3, there is no problem even if 20 is arranged so as to be arranged on the traveling oil motor 21 side, that is, on the surplus oil distribution side. Specifically, the traveling directional control valve 29 and the elevating / lowering directional control valve 24 are made into two directional directional control valves in the same manner as in the case of steering and elevating / lowering shown in FIG. realizable. With such a configuration, it is possible to increase the lifting capacity of the luggage.

(Effects of the Invention) As described in detail above, according to the present invention, the flow divider is provided on the child lift side, and the flow divider divides the hydraulic oil into the hydraulic actuator mounted on the child lift. As a result, the number of hoses to be piped between the parent lift and the child lift can be reduced from the conventional six to two, which causes a failure of the hose and piping parts such as a hose reel for guiding the hose. The degree can be reduced, and the front field of view can be improved and improved as the number of pipes is reduced.

In addition, since the flow divider divides the hydraulic oil into each hydraulic actuator, compared to the conventional method that may supply the entire amount of hydraulic oil to one hydraulic actuator, It is a system that supplies less pressure from the hydraulic unit because it produces less shock and it is easy to obtain minute movements. Moreover, a part of hydraulic oil is preferentially supplied to the steering system and surplus oil is supplied to the traveling system. When the maximum supply of hydraulic oil is set to the same level as before, the control range of running speed can be expanded, and especially in the vicinity of idle rotation, the amount of hydraulic oil sent to the running oil motor is small and smooth with less shock. It is possible to start easily.

[Brief description of drawings]

1 is a hydraulic circuit diagram of a hydraulic actuator showing an embodiment of a control device of the present invention, FIG. 2 is a block diagram thereof, FIG. 3 is a block diagram showing a control device of another embodiment of the present invention, and FIG. FIG. 1 is a schematic side view of a parent-child forklift, and FIG. 5 is a block diagram showing a conventional hydraulic actuator control device. 1 ... Parent lift 2 ... Mast 3 ... Lift bracket 4 ... Child lift 18 ... Flow divider 19 ... Power steering cylinder 20 ... Lift cylinder 21 ... Oil motor 23,24,29 ... Electromagnetically operated directional valve 31 ... Hydraulic unit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayuki Miyano 2-chome Toyota-cho, Kariya city, Aichi Prefecture Toyota Industries Corporation (72) Inventor Akira Okura 1-cho, Toyota-shi, Aichi Toyota motor vehicle Within the corporation

Claims (1)

[Claims] 1. A parent-child forklift equipped with a detachable child lift as an elevating member of the parent lift, the child lift including hydraulic actuators for traveling, steering, and ascending / descending with a hydraulic unit on the parent lift side. A flow divider that divides the hydraulic oil into a certain amount of preferential flow and surplus flow is installed on the child lift side in the pipeline that connects to the hydraulic actuator on the child lift side, and steering is provided on the priority diversion side of this flow divider. A hydraulic actuator for traveling, a traveling hydraulic actuator on the surplus diversion side, and a lifting hydraulic actuator on either the priority diversion side or the surplus diversion side,
Further, a hydraulic actuator control device for a child lift in a parent-child forklift in which an electromagnetically operated directional control valve is provided between the flow divider and each hydraulic actuator.