JPH0577598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a side shift device as an attachment installed on a forklift.
The present invention relates to a device for positively shifting a fork so that the center of load of a load on the fork is located within an allowable range including the vehicle centerline.

(Prior Art) Generally, a side shift device for a forklift has a configuration in which a shift cylinder is actuated to side shift the fork to the left or right by tilting a side shift lever and switching a hydraulic control valve. It's summery.

(Problem to be Solved by the Invention) Therefore, in the conventional side shift device, after loading the fork in a position where the fork is side-shifted to the left or right, the fork is returned to the approximate center position of the vehicle together with the finger bar. Since the neutral return operation is left solely to the driver, the driver may inadvertently drive the vehicle while neglecting the return operation. However, traveling with a fork, that is, with the load biased to either the left or right side, is dangerous because the lateral stability of the vehicle is poor. In addition, even if the driver returns the fork to the center position or loads the fork without shifting to the side, the load may be loaded to one side or the other. Because the load center of the load itself is uneven, an uneven load may be applied, and therefore, traveling under such conditions is naturally accompanied by danger.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention provides a lift bracket that is moved up and down along the mast, and a lateral movement of the lift bracket in the left and right direction via a guide member. means for detecting the lift height of the fork in a forklift comprising a finger bar for supporting the fork that is mounted so as to be capable of supporting the fork, and a shift cylinder for moving the finger bar laterally;
Means for detecting the backward tilt angle of the mast, means for detecting the left and right tilt angle of the vehicle body, and detection signals from each of the detection means to bring the lift height of the fork and the backward tilt angle of the mast within the respective set ranges (running posture). and a control circuit that outputs a correction operation signal to the electric control valve for controlling the shift cylinder when the tilt angle of the vehicle body exceeds a set allowable range. be.

(Function) When the driver picks up cargo using a fork in normal cargo handling operations and then assumes a driving position,
That is, when the fork is moved to a height position suitable for running and the mast is tilted back to a position suitable for running, each of these detection signals is input to the control circuit. At this time, if the signal input to the control circuit from the vehicle's inclination angle detection means indicates an unbalanced load of the cargo, the control circuit outputs a correction operation signal to the electric control valve for controlling the shift cylinder. . Therefore, by actuation of the electric control valve, the shift cylinder moves the fork together with the finger bar to the light load side. That is, the present invention is configured to positively shift the fork for correction so that the load center of the cargo is located within an allowable range including the vehicle center line when the vehicle assumes a running attitude after loading the cargo. Note that the electric control valve is returned to the neutral position as the fork returns.

(Example) Hereinafter, an example of the present invention will be specifically described based on the drawings.

In FIG. 1, 1 is a mast that is tilted forward and backward by a tail cylinder 2, 3 is a lift cylinder that raises and lowers an inner mast 1a of the mast 1,
Reference numeral 4 denotes a lift bracket that is moved up and down along the inner mast 1a, and a finger bar 6 that supports a fork 5 is attached to the front surface of the lift bracket 4 so as to be movable laterally in the left-right direction via a guide bar 7. It is adapted to be moved by a shift cylinder 8. 9 is the oil pump,
10 is an oil tank, and 11 is an electric control valve (electric oil control valve) that controls supply and discharge of hydraulic oil to and from the shift cylinder 8.

Reference numeral 12 indicates a side shift cargo lever that automatically returns to the neutral position, and 13 indicates an angle sensor (for example, a rotary potentiometer) that detects the tilting angle of the cargo handling lever 12. The output voltage is converted into a digital value via an A/D converter (not shown) and input to the control circuit 14. The amount of hydraulic oil supplied and discharged by the electric control valve 11 is controlled by an actuation signal from a control circuit 14 based on this detection signal. Reference numeral 15 denotes a pressure switch, for example, as a load sensor attached to the hydraulic piping of the lift cylinder 3 in order to detect the load of the cargo on the fork 5.
ON and OFF, and the ON and OFF signals are controlled by the control circuit 1.
4 is input.

Reference numeral 16 denotes a level switch containing mercury, for example, as a vehicle body angle sensor installed at an appropriate position on the vehicle body 17 in order to detect the tilt angle of the vehicle body 17 due to an unbalanced load. It has two contacts for left tilting, and each of these contacts is set to be OFF when the vehicle body 17 is horizontal, the right contact is ON when the vehicle body 17 is tilted to the right, and the left contact is ON when tilting to the left. There is. Then, these ON and OFF signals are input to the control circuit 14. 18 is a backward tilt angle sensor (for example, a rotary potentiometer) attached to the tail cylinder 2 to detect the backward tilt angle of the mast 1;
A voltage corresponding to the tilt angle is output, and the output voltage is converted into a digital value via an A/D converter (not shown) and input to the control circuit 14. 19 is a proximity switch attached to the lift bracket 4 as a lift height sensor for detecting the lift height of the fork 5, and is turned on and off by a vertically long dog 20 attached to face the mast 1.
The ON and OFF signals are input to the control circuit 14.

Thus, the control circuit 14 controls each of the sensors 15,
Based on the detection signals from 16, 18, and 19, a correction operation signal is output to the electric control valve 11.
Specifically, this correction operation signal is set to be output when the vehicle assumes a running attitude while a load of a certain load (for example, 30 kg) or more is loaded on the fork 5. In this embodiment, the conditions for the running posture are that the backward inclination angle of the mast 1 is, for example, 8 to 13 degrees, and the lift height of the fork 5 is, for example, 150 to 500 mm. Further, the allowable range of the inclination angle of the vehicle body 17 is set to, for example, ±1 degree.

Regarding the control of the lift cylinder 3 and the tail cylinder 2, a manual type oil control valve is switched by tilting the lift and tail load handling levers, or an angle sensor is used as in the case of the shift described above. Any type that uses an electric control valve to switch may be used.

Next, the corrective shift of the fork 5 will be explained based on the flowchart shown in FIG. When the vehicle's key switch is turned on, the initial settings are made in step (1), and the lift height data is read in step (2). In step (3), the lift height of the fork 4 is set to the set value (150 to 500 mm). ), and if NO, return to step (2) and repeat (2)-(3). If YES, proceed to step (4), read mast 1 aft angle data, and then proceed to step (5).
Determine whether the backward tilt angle of mast 1 is within the range of the set value (8 to 13 degrees), and if NO, proceed to step (2).
Return to step (2)-(3)-(4)-(5), and if YES, proceed to step (6), read the load data, and then proceed to step (7).

In step (7), it is determined whether the load on the fork 5 is greater than or equal to the set value (30Kg), and if NO, the process returns to step (2) and steps (2)-(3)-(4)- (5)−(6)−(7
)
Repeat. If YES, proceed to step (8), read the inclination angle data of the vehicle body 17, and then
Proceed to step (9). In step (9), it is determined whether the inclination of the vehicle body 17 exceeds the permissible range (±1 degree), and if NO, the process returns to step (2) and steps (2)-(3)-
Steps (4)-(5)-(6)-(7)-(8)-(9) are repeated, but if YES, proceed to step (10) and determine which side is leaning: left or right. If it is determined that the shift cylinder is tilted to the left, the process proceeds to step (11) where a correction operation signal is output to the electric control valve 11 for controlling the shift cylinder. Therefore, the fork 5 is moved from left to right together with the finger bar 6. If it is determined that the fork 5 is tilted to the right, the process proceeds to step (12), where a negative correction operation is performed on the electric control valve 11. In order to output the signal, the electric control valve 11 is operated in the opposite direction to that described above, and the fork 5 is moved together with the finger bar 6 from right to left. After passing step (11) or (12), return to step (8),
Repeat -(9)-(10)-(11) or (12). and,
When the load center of the cargo is located within the allowable range including the vehicle center line by moving the fork 5, the tilt of the vehicle body 17 due to the uneven load is corrected, so the step
If the decision in (9) is NO, return to step (2),
The corrective actuation signal to the electric control valve 11 is discontinued, and the electric control valve 11 is automatically returned to the neutral state.

The above-mentioned corrective shift of the fork 5 is not performed when the vehicle is in the loading position, that is, when the mast 1 is tilted forward or straight, or when the fork 5 is ascending to pick up a load from a high place, and is only performed as described above. This is executed only when there is a load of a certain load or more on the fork and the running posture conditions are satisfied.

In addition, according to this embodiment, the fork 5 is automatically corrected and shifted when the running posture conditions are satisfied, and therefore, depending on the work content, this may sometimes be rather inconvenient. Therefore, the above-mentioned inconvenience can be solved by, for example, installing a cancel button and configuring the control circuit 14 so that the operation by the driver takes priority.

Furthermore, in this embodiment, when the load of the cargo is detected and the load is below the set load, the step is returned, but if the tilt angle of the vehicle body exceeds the allowable range, it will inevitably exceed the set load. Therefore, it is possible to implement the present invention even if the load detection is omitted.

Note that each sensor described in the embodiments is merely an example, and may be changed to other sensors.

(Effects of the Invention) As described in detail above, according to the present invention, in the side shift device of a forklift, the fork is actively moved so as to position the load center of the load within an allowable range including the vehicle center line during traveling. Since corrective shifts can be performed automatically, work efficiency can be improved compared to conventional systems that relied on the driver's intuition, and a stable posture can be ensured to improve driving safety. It is something.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a control system diagram of a side shift control device (however, for convenience of explanation, the side shift device is shown with imaginary lines);
FIG. 2 is a flowchart of the control circuit. 1... Mast, 5... Fork, 6... Finger bar, 7... Guide bar, 8... Shift cylinder, 11... Electric control valve, 12... Loading lever, 13... Angle sensor, 14... control circuit, 1
5...Load sensor, 16...Vehicle body angle sensor, 1
7...Vehicle body, 18...Backward tilt angle sensor, 19...
Lift height sensor.

Claims (1)

[Claims] 1. A lift bracket that is moved up and down along the mast, a finger bar for supporting the fork that is attached to the lift bracket via a guide member so as to be able to move laterally in the left and right direction, and a shift cylinder that moves the finger bar laterally. A forklift equipped with a forklift includes a means for detecting the lifting height of the fork, a means for detecting the backward tilt angle of the mast, a means for detecting the tilt angle of the vehicle body in the left and right direction, and a means for detecting the lift of the fork based on the detection signal of each of the detection means. When the height and mast backward tilt angle are within the set ranges, and the vehicle body's horizontal tilt angle exceeds the set range,
A side shift control device for a forklift, comprising a control circuit that outputs a correction operation signal to the electric control valve for controlling the shift cylinder.