JPS5915876B2 - Crane running speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a crane that uses a hydraulic motor as a travel drive source, and in order to prevent a suspended load suspended from a wire rope from causing pendulum motion, the present invention is designed to control the acceleration during acceleration and deceleration. This invention relates to a crane traveling speed control device whose pattern is an approximate sine wave.

In a crane that suspends and transports a heavy load using a wire rope, when the crane accelerates from a stopped state, reaches a certain speed, and then operates at a constant speed, the fulcrum of the wire rope and the center of gravity of the suspended load must be aligned at the end of acceleration. If there is an angle between the connecting line and the vertical axis, a constant cycle pendulum motion will be superimposed on the suspended load in addition to the movement in the forward direction during constant speed operation of the crane.

This pendulum motion is not only dangerous for operation, but also causes repeated positive and negative external forces to act in the direction of movement, adversely affecting the performance and life of the crane.

Furthermore, if there is a pendulum movement in the suspended load even when the crane is stopped, the swing may interfere with other objects even though it has been transported to the destination, causing problems such as having to wait until the swing of the suspended load becomes smaller. there were.

Generally, when operating this type of crane manually, the operator adjusts the acceleration/deceleration speed of the crane based on experience to minimize swinging of the suspended load, so as to operate without swinging of the suspended load.

In addition, in the case of automatic operation, it is necessary to eliminate the pendulum movement of the suspended load by providing some means to adjust the acceleration/deceleration.

The present invention has been made in view of the above circumstances, and analyzes the motion of the suspended load assuming that it is an ideal simple pendulum. This method focuses on the fact that when a sine wave is applied, the suspended load is located directly below the fulcrum at the end of acceleration and does not swing during constant speed movement.

That is, as shown in Figure 1, assuming that the suspended load is an ideal simple pendulum, and the displacement, velocity, and acceleration of the crane body in the advancing direction are respectively defined as X, C, and α, the equation of motion is as follows:
) is expressed as the formula.

-9,9゜Here, if the swing angle θ of the suspended load is very small, sin θ and θ become approximate, and sin θζθ
Then, the above equation 1) is expressed as the following 2).

becomes.

Now, suppose that the displacement of the crane in the X direction is given by a sine wave, and its amplitude is a and its angular velocity is ω, then equation 2) is expressed as equation 3).

Solving this equation 3) yields the following equation 4).

If the velocity V and swing angle θ are plotted on the vertical axis and the time t is plotted on the horizontal axis, and the ratio n between the natural angular velocity ωn determined by the wire length l and the angular velocity of the crane's acceleration is used as a parameter, it will look like Figure 2. become.

In FIG. 2, in order to equalize the speed at the end of acceleration for each parameter, the speed V and the deflection angle θ are multiplied by each parameter n.

As is clear from Fig. 2, the acceleration α of the crane is n=ωn10)=2,3,4,...(n≧2
), the suspended load will be located directly below the fulcrum at the end of acceleration and will not swing during constant speed movement.

Although not shown in FIG. 2, the amplitude during acceleration is small compared to triangular waveform acceleration with the same acceleration time and the same final velocity.

In addition, in the case of deceleration, by going through the completely opposite process to acceleration, it is possible to stop directly below the fulcrum of the suspended load.

In an autoloader type crane device that repeatedly transports a heavy object of a fixed shape from one predetermined position to another,
Since the length of the wire rope is constant when transporting a suspended load, the inherent angular velocity ωn determined from the length of the wire is constant,
Therefore, since the angular velocity ω of acceleration is an integral multiple of ωn, the angular velocity ω can be determined by selecting a multiple.

Therefore, the above-mentioned acceleration/deceleration pattern of the crane device becomes a constant pattern, and if the traveling speed of the crane device is controlled using the same pattern, the suspended load can be transported without causing load swing for the reasons mentioned above.

The present invention uses a hydraulic motor as the crane traveling drive source of the above-mentioned autoloader type crane device, and uses a proportional flow control valve to adjust the flow rate of pressure oil supplied to the hydraulic motor during acceleration and deceleration. By controlling the valve operation with an approximate sine wave, the acceleration/deceleration pattern of the crane travel is made into an approximate sine wave.

The crane traveling device will be specifically explained below with reference to FIG. 3, which is a hydraulic circuit diagram of the embodiment.

11 is a hydraulic motor which is a traveling drive source of the crane device;
2 is a reduction gear train that reduces the rotation of the hydraulic motor 11; 13;
is a running wheel that is rotationally driven by a hydraulic motor 11 via a reduction gear train 12 and rolls on a track.

When the hydraulic motor 11 is activated, the traveling wheels 13 are driven to rotate, and the crane device is guided by the track and moved.

14 is a proportional flow control valve that controls the flow rate of pressure oil supplied to the hydraulic motor 11; 15 is an electromagnetic directional control valve that switches the direction of the pressure oil supplied to the hydraulic motor 11; and 16 is an overload prevention relief valve. .

17 is a linear function generator that generates an output signal with an approximate sine wave voltage waveform when receiving a constant voltage input signal; 18 is a proportional flow rate control valve that amplifies the approximate sine wave generated by the linear function generator 17; This is a proportional control valve drive amplifier that generates a signal necessary to drive 14 proportional control valves.

With such a configuration, when a signal to start crane travel is given, the electromagnetic directional control valve 15 is selected to determine the direction of crane travel, and the polygonal function generator 1T generates an approximate sine wave signal. , will operate the proportional control valve of the proportional flow control valve 14 via the proportional control drive amplifier 1B.

The proportional flow rate control valve 14 controls the flow rate of the pressure oil sent from the pump to a flow rate proportional to the sent signal, and supplies the flow rate to the hydraulic motor 1'1.

On the other hand, since the traveling speed of the crane is proportional to the flow rate supplied to the hydraulic motor, the acceleration pattern of the relief becomes an approximate sine wave. This is possible.

Furthermore, even when the crane is stopped, the flow rate of the pressure oil supplied to the hydraulic motor 11 is reduced in proportion to the approximate sine wave, so the deceleration pattern of the crane becomes an approximate sine wave, causing the suspended load to swing due to the above-mentioned reason. It can be stopped without any trouble.

'As detailed above, in the present invention, since the acceleration/deceleration pattern during acceleration/deceleration of the crane is an approximate sine wave, it is possible to eliminate the swing of the suspended load when the crane is accelerating/decelerating and when traveling at a constant speed. This enables unmanned crane operation and automation.

In addition, by adopting a hydraulic motor as the crane travel drive source and controlling the flow rate of pressure oil supplied to the hydraulic motor, the acceleration/deceleration pattern described above can be easily generated, especially when the length of the wire rope is constant. In some autoloader type crane devices, the acceleration/deceleration period is not variable (it can be unique, so control is very simple).

[Brief explanation of the drawings] Figure 1 is a diagram showing the relationship between the traveling direction of the crane and the swing of the suspended load, Figure 2 is a diagram showing the relationship between the speed of the crane and the swing angle of the suspended load, and Figure 3 is the diagram showing the relationship between the crane's traveling direction and the swing of the suspended load. 1 is a hydraulic circuit diagram of a crane travel speed control device according to an embodiment of the invention. 11...Hydraulic motor, 13...Traveling wheel, 14...Proportional flow control valve, 17...
- Linear function generator.

Claims (1)

[Claims] 1. In a crane traveling device that uses a hydraulic motor as a traveling drive source, a directional switching valve and a proportional flow control valve that direct the direction and flow rate of pressure oil supplied to the hydraulic motor, and a wire for hanging a load. A polygonal function generator that generates an approximate sine wave with a period that is an integral multiple of the natural period determined by the length of the rope, and the approximate sine wave generated by the generator is amplified to drive the proportional control valve of the proportional flow control valve. The crane is equipped with a proportional control valve-driven amplifier that serves as a control signal for the crane, and the acceleration/deceleration pattern during acceleration/deceleration of the crane is an approximate sine wave, thereby eliminating swing of the suspended load when the crane is running at a constant speed and when the crane is stopped. Travel speed control device.