FI68596B - FOERFARANDE OCH ANORDNING FOER STYRNING AV BALANSLYFT - Google Patents

Description

68596

METHOD AND APPARATUS FOR AUTOMATING BALANCE LIFT CONTROL

The invention relates to a method and a device for automating the control of a pneumatic balance lift, which balance lift consists of a frame, a lifting arm, a control valve rail and a lifting cylinder. Control automation makes it easier to handle different loads.

The purpose of the balance lift is to facilitate the transfer of the load in warehouses, machine shops, etc. The balance lift supports the load so that it is easy for the user to move the load up, down or to the sides. In this case, the force required by the user depends only on the lift's own friction and not on the size of the load.

The vertical movement of the load takes place on some lifts by means of electricity, compressed air or hydraulics that drive the lift. In this case, lifting or lowering is effected, for example, by turning the lever. In the hoist in question, lifting and lowering take place by lightly lifting or pressing the load by hand. The hoist control valve list then ensures that the correct balancing force is maintained.

In current hoists, the balancing pressure required for the lifting cylinder is usually obtained by pressing the pushbutton several times, whereby the pressure gradually increases. This slows down lifting and transfer operations, especially when handling different loads.

The above drawbacks can be eliminated by the method and device according to the invention. The invention is characterized by the features of claims 1 and 2.

With the pneumatic system according to the invention, the increase of the balancing pressure is started by pressing the pushbutton once and the increase ends automatically when the pressure corresponding to the load has been reached. The operation is independent of the size of the load. The invention speeds up the handling of loads of different sizes.

The following is a more detailed description of the invention with reference to the accompanying drawing, in which:

Figure 1 shows a schematic illustration of an equilibrium lift and

Figure 2 shows the control automation according to the invention.

The balance lifter shown in Fig. 1 consists of a body 20, a lifting arm 21, a control valve system 22 and a lifting cylinder 14.

Figure 2 shows the operation of the control automation. Load balancing starts when the directional valve 10 is pressed. The impulse from the valve 10 controls the directional valves 3 and 4 to their operating positions. Valve 3 supplies compressed air to the control of the pressure regulator 12. The pressure regulator 12 in turn controls the pressure balance 13. The valve 4 supplies compressed air to the servo pressure connection of the amplifier valve 1.

As the pressure regulator 12 raises the control pressure of the pressure balance 13, compressed air can flow into the lifting cylinder 14. When the pressure corresponding to the load is reached in the lifting cylinder 14, the piston moves upwards. In this case, the air on the piston rod side is compressed and the pressure in this state increases. This increase in pressure is detected by the amplifier valve 1, which switches to the operating position. The impulse from this valve directs the Directional Valves 3 and 4 to their rest positions, whereby the air supply to the control of the pressure regulator 12 is interrupted and the pressure reached so far remains in the control. The impulse from the amplifier valve 1 also opens the directional valve 2, which combines the control pressure of the regulator and the pressure prevailing in the lifting cylinder 14 and thus compensates for any differences.

The balancing pressure is released by valve 11.

3,68596

Check valves 8 and 9 prevent possible leaks.

The resistance valve 5 regulates the rate of increase of the balancing pressure. The resistance valve 6 regulates the opening time of the valve 2. The resistance valve 7 controls the response speed of the amplifier valve 1.

The system according to the invention can also be implemented with another type of amplifier valve. The control pressure required by the valve, which must be less than 0.1 bar, is crucial. If the amplifier valve does not require a separate servo pressure, the directional valve 4 can be removed. The description and figures of the invention are only intended to clarify an embodiment of an automation method for controlling the balance lift control. Embodiments and scope of the invention may vary widely within the scope of the claims.

Claims (5)

A method for automating the control of a balance lifter, the balance lifter comprising a body, a lifting arm, a control valve rail and a lifting cylinder, characterized in that the control automation is effected by valve arrangements in which an increase in pressure above the piston is detected by a piston valve (1) that the increase in balancing pressure ceases when the pressure corresponding to the load is reached. Device for carrying out the method according to claim 1, characterized in that the control automation according to the system comprises an amplifier valve (1) which detects piston movements and directs the directional valves (3, 4) to their rest positions, interrupting the air supply to the pressure regulator (12) . Device according to Claim 2, characterized in that the directional control valves (3, 4) belonging to the control automation are connected to the directional control valve (10), from which the impulse controls the directional control valves (3, 4) to their operating positions. Device according to claims 2-3 4,68596 Device according to Claims 2 to 4, characterized in that the non-return valves (8, 9) prevent any leaks in the system and the balancing pressure is removed by means of the directional control valve (11).