JPH0352578Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a platform elevation control device for a high-lift loader that raises and lowers a cargo platform using a pair of hydraulic cylinders, such as a high-lift loader for loading cargo onto an aircraft.

[Technical background of the invention and its problems]

This type of high-lift loader has, for example, loading platform arms 3A to 6 that support loading platforms 1 and 2, as shown in FIG.
A, 3B to 6B (among them, 3A to 6A are at the front in the drawing, and 3B and 6B are on the other side of 3A to 6A in the drawing) are connected to hydraulic cylinders 7A, 8A, 7B,
8B (Of these, hydraulic cylinders 7A and 8A are located at the front in the drawing and drive the loading platform arms 3A to 6A.
On the other hand, hydraulic cylinders 7B and 8B are 7A and 7B in the drawing.
It is located on the other side of the platform and drives the loading platform arms 3B to 6B. ) to raise and lower the cargo platforms 1 and 2.
At this time, it is necessary for the pair of hydraulic cylinders 7A, 7B or 8A, 8B for each of the loading platforms 1 and 2 to move in synchronization with each other.

Conventionally, a method for achieving this synchronization has been to use a flow splitter valve to ensure that equal amounts of oil flow into and out of a pair of hydraulic cylinders, but the accuracy of the flow splitter valve is generally 2 to 3%, and the stroke For a 2000mm hydraulic cylinder, the difference is 40 to 60mm. Particularly when inching, this difference is accumulated, causing the loading platform to tilt, and furthermore, the loading platform or loading platform arm to be deformed.

On the other hand, synchronization can be achieved by increasing the rigidity of the loading platform and loading platform arm, but this has the drawback of increasing the load on the hydraulic cylinder and the weight of the vehicle.

[Purpose of invention]

The purpose of the present invention is to achieve highly accurate synchronization and minimize the tilting of the loading platform without increasing the load on the hydraulic cylinder or the weight of the vehicle.

[Summary of the idea]

In this invention, both of a pair of hydraulic cylinders are equipped with a sensor that detects their movements, the output signal of the sensor that detects the movement of one hydraulic cylinder is used as a feedback signal, and the output signal of the other hydraulic cylinder is used as a target value signal. The one hydraulic cylinder is driven by a servo mechanism.

[Example of idea]

FIG. 2 shows an outline of the control device according to the present invention. In the figure, 11A and 11B are electromagnetic proportional valves that raise and lower cylinders 7A and 7B, respectively;
sends oil to the hydraulic cylinders 7A, 7B via the electromagnetic proportional valves 11A, 11B,
Hydraulic pumps 13A and 13B for driving B up and down are inclinometers shown in FIG. 3, each of which is constituted by a potentiometer, for example, and detects the inclination angle of the platform arm on the side of the hydraulic cylinders 7A and 7B. Reference numeral 14 denotes an operating device for instructing the lifting and lowering of the loading platform, and has, for example, an operating lever as shown in the figure. Note that an operating push button switch may be provided instead of the operating lever. 15 is a controller, an operating device 14, an inclinometer 1
Signals 14y, 13Ay, 13 from 3A, 13B
Based on these signals, a drive control signal 7Ax (up signal 7Au or down signal 7Ad) for the cylinder 7A and a drive control signal 7Bu (up signal 7Bu or down signal 7Bd) for the cylinder 7B are generated.

FIG. 1 shows the internal configuration of the controller 15.

As shown in the figure, the operation signal 14y from the operation device is input to the electromagnetic proportional amplifier 22 through the delay circuit 21, and the output 7Ax of the electromagnetic proportional valve amplifier 22 determines whether the operation by the operation device 14 instructs an upward movement or a downward movement. Contents 7Au, which vary depending on what you are instructing.
It becomes 7Ad.

For example, the output 14y of the operating device 14 is a DC voltage signal having a different value depending on the contents of the instruction, and in that case, a CR integration circuit may be used as the delay circuit 21. The delay circuit 21 converts the actuator output signal 14y, which changes in a stepwise manner, into a signal that gradually rises or falls, thereby enabling the cylinder driven by the amplifier 22 to perform a shockless operation, and also making it easy for the other cylinder to follow. This was provided to improve synchronization.

The output 7Ax of the amplifier 22 causes the solenoid valve 11A to
is controlled, and the cylinder 7A is driven. The output signal 13Ay of the inclinometer 13A on the cylinder 7A side is inputted to the servo amplifier 24 as a target value signal Vsig via a D/A (digital/analog) converter 23. On the other hand, the output signal 13By of the inclinometer 13B on the other cylinder 7B side is transmitted to the D/A converter 2.
Servo amplifier 24 as feedback signal Vfb via 5
is input. Based on the deviation between Vsig and Vfb, the servo amplifier 24 provides an output to the electromagnetic proportional valve amplifier 26 to reduce the deviation. amplifier 26
determines the content of its output 7Bx in response to the signal from the servo amplifier 24. That is, cylinder 7B
When it is necessary to raise the signal, a signal 7Bu is generated, and when it is necessary to lower it, a signal 7Bd is generated.

In this way, for one cylinder 7B, the output of the inclinometer 13A that detects the movement of the other cylinder is set as the target value signal Vsig, and the
A servo mechanism is provided that uses the output of the inclinometer 13B that detects the movement of B as the feedback signal Vfb, and this servo mechanism controls the one cylinder, so that the one cylinder accurately follows the other cylinder. This improves synchrony.

[Effect of idea]

As described above, according to the present invention, two cylinders can be synchronized with high precision without increasing the rigidity of the loading platform or loading platform arm, and therefore without increasing their weight.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the internal configuration of the controller of the control device of the present invention, Fig. 2 is a schematic diagram showing the overall structure of the control device of the present invention, and Fig. 3 is a schematic diagram showing an example of a high lift loader. It is. 1... Loading platform, 3A, 3B, 4A, 4B... Loading platform arm, 7A, 7B... Hydraulic cylinder, 13A,
13B... Inclinometer, 21... Delay circuit, 24...
servo amplifier.

Claims (1)

[Claims for Utility Model Registration] 1. In a device that uses a pair of hydraulic cylinders to control the lifting and lowering of the platform of a high-lift loader, a sensor is provided to detect the movement of each hydraulic cylinder, and one hydraulic cylinder is connected to the A servo mechanism is provided that uses the output signal of a sensor that detects the movement of the cylinder as a feedback signal and the output signal of the sensor that detects the movement of the other hydraulic cylinder as a target value signal, and this servo mechanism drives the one hydraulic cylinder. A platform elevation control device for a high-lift loader, wherein an operation signal for the other hydraulic cylinder is inputted via a delay circuit. 2. The device according to claim 1, wherein the delay circuit comprises an integrating circuit.