JP2536076B2 - Reach type forklift reach operation control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reach operation control device for a reach type forklift equipped with a load stabilizer for holding a load.

(Prior Art) In a conventional reach-type forklift with a road stabilizer, the load stabilizer generally moves forward and backward together with the fork. With such a type of forklift, it is possible to stabilize the load when moving the load forward and backward. On the other hand, the presence of a road stabilizer is often an obstacle when loading or unloading luggage on a covered truck or multi-tiered shelves. From such a thing,
A type in which a load stabilizer is provided on the side of a support member that supports the fork so that it can move back and forth has been proposed, for example, Japanese Utility Model Publication No. 61-130599.

In the forklift disclosed in the above publication, during the reach operation of the reach cylinder, that is, during the forward operation of the fork, hydraulic oil is supplied to both the reach cylinder and the stabilizer cylinder through the flow dividing valve, and is related to the reach operation of the fork. As a result, the holding plate of the load stabilizer rises, and this may cause the load to collapse or be damaged or the load stabilizer to be damaged if the reach operation is performed while the load is being held by the holding plate. Is being prevented.

(Problems to be Solved by the Invention) However, in the control method using the flow dividing valve described above, the reach cylinder and the stabilizer cylinder operate simultaneously in terms of the circuit, but in the normal case, the presser plate and the stabilizer cylinder are combined. Since the cushioning member is interposed in the connecting portion, the separating action of the holding plate from the load tends to be delayed compared to the reach action of the fork, which causes a problem that the dragging phenomenon of the load occurs. The phenomenon is particularly noticeable when handling elastic loads. Also, when the priority circuit is configured so that the rising operation of the stabilizer cylinder precedes the reach operation of the reach cylinder, the reach cylinder starts operating after the stabilizer cylinder reaches the stroke end.
Another problem occurs that the loss time is large.

Therefore, it is an object of the present invention to provide a reach operation control device for a reach type forklift that can solve the above-mentioned conventional problems.

(Means for Solving the Problems) In order to solve the above problems, according to the present invention, a support member that supports a fork so as to be movable back and forth is provided with a load stabilizer for holding down a load so that the load stabilizer can move up and down. In a reach type forklift configured to control the operation of the reach cylinder by starting / stopping a cargo handling hydraulic pump or switching an electromagnetic hydraulic control valve,
A configuration in which a sensor for detecting the pressing of a load is provided on the pressing plate of the load stabilizer, and an electric circuit for controlling the cargo handling hydraulic pump or the electromagnetic hydraulic control valve is deactivated based on an output signal of the sensor. It is what

(Effect) Therefore, when the load on the fork is pressed by the pressing plate of the load stabilizer, the electric circuit of the cargo handling hydraulic pump or the electromagnetic hydraulic control valve is deactivated by the detection operation of the sensor. Therefore, in this state, the operating oil is not supplied to the reach cylinder even if the cargo handling lever for reach is operated. That is, the reach action of the fork is not performed when the load is held by the holding plate, and the reach operation of the fork by the reach cylinder is possible when the holding is released.

(Example) Hereinafter, the Example of this invention is concretely described based on drawing. This embodiment is intended for a battery vehicle, and in FIG. 1 showing the entire reach-type forklift, 1 is a vehicle body, 2 is a leg, 3 is a mast, 4 is a lift cylinder, and 5 is a tilt cylinder. Is. A reach bracket 7 as a supporting member is attached to the front surface of a lift bracket 6 that moves up and down along the mast 3, and a fork 9 is attached to the front surface of the reach bracket 7 via a pantograph 8 so as to be movable back and forth. , Reach cylinder
It is designed to reach by 10. A window 7a is formed on the reach bracket 7 to improve the front field of view. The lower end side of the pantograph 8 is a rail 11 provided on the lower front surface of the reach bracket 7 and a rail provided on the lower rear surface of the fork bracket 12 supporting the fork 9.
It is engaged with 13 so as to be vertically movable. Further, a backrest 14 is attached to the fork bracket 12, and a concave recess 14a is formed in the center of the upper portion of the backrest 14 as shown in FIG.

The load stabilizer 15 for pressing down the load on the fork 9 is attached to the reach bracket 7. As shown in FIG. 1 to FIG. 3, between the left and right lift brackets 6, a pair of left and right guide rails 16 extending upward from the rear surface of the reach bracket 7 are provided.
Is erected, and the left and right holders are
A roller 17 is attached via a roller 18 so as to be vertically movable.
A support arm 19 is integrally formed or fixed to the upper end of the holder 17, and the support arm 19 extends forward in a substantially horizontal shape, and a pressing plate 20 is provided on the lower front side thereof.
Is stuck. A stabilizer cylinder 21 is erected between the left and right holders 17 and the lower portion is supported by the reach bracket 7 via the bracket, and the upper end of the piston rod 22 is fixed to the base portion of the support arm 19. . Therefore, the load stabilizer 15 is moved up and down by the expansion and contraction of the stabilizer cylinder 20. The width of the support arm 19 is set to be slightly smaller than the width of the recess 14a of the backrest 14, and the load stabilizer 1
5 is designed to fit in the recess 14a near the descending end of the backrest 5, so that the holding plate 20 is fixed to the backrest 14 as shown in FIG.
It is designed to be lowered below the upper end of the.

Then, a sensor 23 of a type for detecting reflected light (infrared ray) from a baggage such as a three-lens distance measuring optical sensor for detecting the pressing of the baggage is attached to the pressing plate 20, In this embodiment, as shown in FIG.
A total of four sensors 23 are installed, one at each of the four corners of 20. As shown in FIG. 4, when the sensor 23 is pressed down, the pad 20a of the pressing plate 20 is considered in consideration of the elastic deformation of the pad 20a of the pressing plate 20 so as not to come into contact with the baggage.
Is attached through a bracket 23a to a position slightly retracted from the lower surface of the.

A limit switch 24 for detecting the height of the load stabilizer 15 is attached to the upper end of the reach bracket 7, and the limit switch 24 is operated by a dog 25 attached to the holder 17. The position and length of the dog 25 are set so that the limit switch 24 is continuously operated while the holding plate 20 is located within the range from the lower end to the upper end of the backrest 14. Further, as shown in FIGS. 5 and 6, in the vicinity of the driver's seat of the vehicle body 1, the cylinders 4,5, 10, 2 are connected.
Hydraulic control valves 26, 27, 28, 29 for controlling 1 are installed,
The cargo handling levers 30, 31, 32, and 33 for lift, tilt, reach, and stabilizer can be individually switched. Also, each cargo handling lever 3
Limit switches 34, 35, 36, 37 for lift, tilt, reach, and stabilizer are arranged corresponding to 0, 31, 32, 33, and these limit switches 34, 35, 36, 37 are
It is set to be turned on when the cargo handling levers 30, 31, 32, and 33 are tilted, and to be kept off at the neutral position.

Next, FIG. 7 shows the electric circuit of the electric motor 38 for driving the cargo handling hydraulic pump. The drive circuit 39 and the control circuit are shown in FIG.
40 is a parallel circuit to the battery 41. The drive circuit 39 is a normally open contact 42a of the electric motor 38 and the electromagnetic contactor 42.
And is connected in series. Also the control circuit
40 is a lift limit switch 34, a tilt limit switch 35, a stabilizer limit switch 37, and a circuit 44 between the key switch 43 and the electromagnetic contactor 42.
Is connected in parallel, and the circuit 44 includes a limit switch 36 for reach and a limit switch for detecting the height of the stabilizer having an AB (normally open and normally closed) contact.
24 and the AB (normally open and normally closed) contacts 23a, 23b, 23c, and 23d of the relay built in the four sensors 23 for detecting the press-down are connected in series. The pilot lamp 45 includes a limit switch 24 for height detection and AB contacts 23a, 23b, 23c, 23 of four sensors 23 for presser foot detection.
The circuit is configured so that it lights up when any one of d and d contacts the A contact side, and it is installed at a position where it can be easily confirmed from the driver's seat.

This embodiment is configured as described above.Therefore, when the cargo handling lever 30 for lift, the cargo handling lever 31 for tilt, or the cargo handling lever 33 for stabilizer is tilted, the limit corresponding to the cargo handling lever. Switch 34 or 35 or 37 is turned on and electromagnetic contactor 42
Is excited and the normally open contact 42a is turned on, so that the electric motor 38 for the hydraulic pump is driven. Further, since the corresponding hydraulic control valve 26, 27 or 29 is switched by the operation of the cargo handling lever 30 or 31 or 33, the hydraulic oil from the hydraulic pump passes through the hydraulic control valve 26, 27 or 29, and the corresponding cylinder 4, 5 or 4. , 21. That is, the lift action of the fork 9, the tilt action of the mast 3, and the elevating action of the load stabilizer 15 are performed regardless of other conditions.

On the other hand, when the cargo handling lever 32 for reach is operated, the reach cylinder 10 is activated only when the holding plate 20 of the load stabilizer 15 is above the upper end of the backrest 14 and is not holding the load. It That is, under the above conditions, the limit switch 24 for height detection
It is separated from 25, and is therefore connected to the B contact as shown in FIG. 7, and the AB contacts 23a to 23d of the relay built in each sensor 23 for detecting the press-down are connected to the B contact side. Therefore, in such a state, if the cargo handling lever 32 for reach is tilted, the electromagnetic contact tank 42 is excited when the limit switch 36 is turned on. Therefore, as in the case described above, the electric motor 38 is driven and the hydraulic oil from the hydraulic pump is switched by the cargo handling lever 32.
Since it is supplied to the reach cylinder 10 via 38, the reach operation of the fork 9 is performed.

However, when the holding plate 20 is pushing the load on the fork 9, the sensor 23 detects the pushing and the AB contacts 23a to 23d of the relay are connected to the A contact side. Even if the cargo handling lever 32 is operated, the electromagnetic contact tank 42 is not energized and the electric motor 38 is not driven. That is, the reach operation of the fork 9 is not performed,
It is possible to prevent troubles such as collapse and deformation of the load due to the reach operation while the load is being held.
Then, at this time, the pilot lamp 45 is turned on to let the operator recognize the cause of the reach inoperability and prompt the pressing-release operation of the pressing plate 20. In this embodiment, since the sensors 23 are installed at the four corners of the holding plate 20, respectively, even if the top surface of the luggage is not flat or uneven, the detection action of at least one sensor 23 Reach operation can be stopped.

If the holding plate 20 is lower than the upper end of the backrest 14, the holder of the load stabilizer 15
Since the dog 25 provided at 17 is in contact with the height detecting limit switch 24 provided at the reach bracket 7, the limit switch 24 is connected to the A contact side. for that reason,
In this state, even if the cargo handling lever 32 for reach is tilted, the reach operation is not performed as in the case described above. Therefore, the backrest 14 that may occur when the fork 9 is reached while the holding plate 20 is at the lowest position. Interference problems are avoided.
Also at this time, the pilot lamp 45 is turned on to allow the operator to recognize the cause of the inoperability of the reach, and to prompt the operator to raise the holding plate 20. In addition, such a holding plate
The control of the reach operation based on the detection of the height position of 20 is that the lowermost end position of the presser plate 20 can be set to a position lower than the upper end portion of the backrest 14, that is, the back on the backrest 14 can be set high. Therefore, it is more effective in stabilizing the posture of the cargo.

Next, another embodiment of the present invention will be described. In the embodiment shown in FIG. 8, the presser foot detection sensor 23 is arranged behind the presser plate 20 by a considerable amount lower than the lower surface of the pad 20a to make the infrared irradiation direction (detection direction) forward, and Since it is attached to the bracket 46 provided on the rear side of the 20 so as to be able to retract upwards via the rod 47 and the spring 48, it is a method of detecting with a horizontal beam, so handle items that are long to the left and right. Sensor if
It is possible to reduce the number of 23. Further, when the luggage is displaced rearward, the luggage may come into contact with the luggage, but in that case, the sensor 23 itself escapes to avoid damage.

In the embodiment shown in FIGS. 9 and 10, the pad 20a of the holding plate 20 is formed with a horizontally long recess 20b, and the horizontally long detection plate 49 arranged in the recess 20b is hung via the rod 50. Attached in a circular shape and pushed downward by the wave washer 51, and the wave washer is used to hold down the load.
The limit switch 52 for detecting the press-down is operated by the upward movement of the detection plate 49 against 51. Therefore, according to this example, it is possible to detect over a wide range, and the cost can be reduced by using the limit switch 52.

The baggage pressing-in detection sensor is not limited to the optical sensor 23 and the limit switch 25 in the illustrated example, and may be of another type such as an ultrasonic sensor. Further, the number of sensors does not have to be plural and at least one sensor can be used. Further, although the present embodiment has been described for a battery vehicle, it can be applied to an engine vehicle. That is, in engine cars, the hydraulic pump for cargo handling is usually a constant drive type by the engine.In this case, therefore, the hydraulic control valve is electromagnetically operated, and the drive circuit of this solenoid is based on the output signal of the press-down detection sensor. It can be realized by arranging it to be in an inoperative state.

(Effects of the Invention) As described in detail above, according to the present invention, when the load on the fork is held by the holding plate of the load stabilizer, the reach operation of the fork is prevented, so that the operator is not accustomed to it. Alternatively, it is possible to prevent the collapse of the load, the damage to the load, the damage to the load stabilizer itself, and the like which may occur when the fork is operated while the load is being pressed by the pressing plate by an erroneous operation. Particularly, in the present invention, since the pressing plate is a method that enables the reach operation of the fork in a state where the pressing of the load is released, the dragging of the load found in the conventional method of simultaneously operating the reach cylinder and the stabilizer cylinder is performed. The problem or the loss time problem found in the system in which the stabilizer cylinder precedes when the reach cylinder operates can be solved, and it is effective as a reach control device for a fork.

[Brief description of drawings]

Drawing shows an embodiment of the present invention, Fig. 1 is a side view showing the whole of a reach type forklift, Fig. 2 is a perspective view showing a reach mechanism of a fork and a load stabilizer, and Fig. 3 is a partially cut plan view of the same. FIG. 4 is a cross-sectional view showing a mounting mode of a presser foot detection sensor, FIG. 5 is a side view showing a cargo handling lever, a hydraulic control valve and a limit switch operated by the lever, and FIG. 6 is a schematic plan view of the same. 7 is an electric circuit diagram for an electric motor for driving a cargo handling hydraulic pump, FIG. 8 is a sectional view showing another embodiment of the present invention, and FIG. 9 is a perspective view showing still another embodiment. Figure 10 is A of Figure 9
It is sectional drawing of a part. 7 ...... Reach bracket 8 ...... Pantograph 9 ...... Fork 10 ...... Reach cylinder 15 ...... Load stabilizer 20 ...... Presser plate 21 ...... Stabilizer cylinder 23 ...... Sensor for detecting presser foot 26 to 29 ...... Hydraulic control valve 30 ~ 33 …… Cargo handling lever 34 ～ 37 …… Limit switch 38 …… Electric motor for hydraulic pump

Claims (1)

(57) [Claims] 1. A support member for supporting a fork so that it can move back and forth is provided with a load stabilizer for vertically pushing a load so that it can move up and down. In a reach type forklift configured to be controlled by switching a hydraulic pressure control valve, a sensor for detecting the pressing of a load is provided on the pressing plate of the load stabilizer, and the cargo handling hydraulic pump or the cargo handling hydraulic pump based on the output signal of the sensor. A reach operation control device for a reach type forklift having a configuration in which an electric circuit for controlling an electromagnetic hydraulic control valve is in a non-operating state.