CS197476B1 - Connection of the three-stage control of the hydraulic flows - Google Patents

Description

The invention solves three-stage control of hydraulic flows with small values of time constants, where the second and third stages are hydraulic valves.

The previously known solution according to the author's certificate no.176933 concerning the connection of hydraulic valves for rapid flow control fully solves the problem of rapid control, but for some applications, eg in the function of the discharge valve of the return rollers of the press, undesirable slow spontaneous sliding of the ram or traverse of the press could occur.

This drawback is overcome by the wiring according to the invention, which is characterized in that the solenoid actuated switchgear, representing the first stage of control, communicates the second stage control valve space with the control pressure line and the waste line, with spaces behind or below the second stage valve cone through the throttle elements to the control chamber of the third stage control valve.

In the accompanying drawings, the circuitry according to the invention is shown. Fig. 1 is a detailed diagram of the circuit according to the invention; Figs. 2, 3 and 4 show alternative connections and Fig.

197 476

197 478 machine system.

Giant. 1. Electromagnetically actuated control valves 2, 3 represent the first stage of control. It allows the second stage control spaces 6, 7 of the second stage valves 4, 5 to be connected to either the pilot pressure line 1 or the β branch 12, so that when the pilot valve space 7 is connected to the pilot pressure line 1, The valve 4 is connected to the discharge branch 12 and vice versa.

The spaces 10, 11 behind the plugs of both valves 4, 5 are connected via throttling elements 13. 14 regulating the flow rate of the liquid β through the control space 18 of the third stage 15 valve. »

The channels 17, 18 are separate channels, each of which may be a plaque fluid supply, a waste branch, or a branch connected to a hydraulic motor, depending on the characteristics required in the particular case. The channels 17, 18 are connected or disconnected by a third stage 15 valve.

All connections shown in Figures 1 to 4 provide control with small values of time constants, but each of the alternatives has its specific characteristics:

OF

The connection according to FIG. 1: The closing speed of the third-stage valve 15 is greater than the opening speed. There is a slight leakage on the valve 5 of the second control stage, both when the valve 15 of the third control stage is opened and closed.

The connection according to FIG. 2: The closing speed of the third stage 15 valve is less than the opening speed. There is a slight leakage on the valve 15 of the third control stage.

The connection in FIG. 3: The closing speed of the third stage control valve 15 is the same as the opening speed. When the third stage 15 valve is closed, there is a slight leak on the second stage 5 valve.

The wiring of FIG. 4 differs from that of FIG. 1 in that the closing speed of the third stage 15 valve is greater than when using the first alternative.

Individual alternatives can be applied both to the actuator valves - both the return and return space of the hydraulic cylinder, as well as to the discharge valves - the return and return space of the hydraulic cylinder, as well as to the relief valves of the pumps.

When choosing an alternative, it is necessary to consider first of all the requirements on the speed of opening against the closing speed of the third stage valve 15, the accessibility of even slight leaks and the connection with the dynamics, ie mainly in relation to the inertia masses of the press.

The spaces of the controls and the spaces behind the valve plug are sealed to each other by gluing, i.e. they do not occur if the same pressures exist in these spaces.

However, leakage occurs when pressures occur in the control space and the space under the plug.

By engaging in accordance with the invention, it achieves the transfer of leakage from the third stage dimension to the second stage dimension, thereby substantially reducing its value.

The connection of the connection according to the invention to the hydraulic system of the machine can be seen in FIG. In this case, a branch of the return space 20 is connected via the return valves 20 in which the pressure at rest of the press rises by rolling out the weight of the sliding masses, but the inlet branch from the pump 21 o to the control pressure branch 22. Some of the branches 20, 21, and 22 have been moved or nice to be connected, but there was a non-sponge-like connection here. compressibility - for example, at high air content nobo gas in the liquid.

OF THE INVENTION

Claims (2)

OF THE INVENTION 1. Connection of three-stage control of hydraulic flow rates and small values of time constants with low pressure branch Z Selecting the maximum pressure indicated by the electromagnetically actuated switchgear (2, 3) completes the first stage of control, communicates control of the spaces (6, 7) of valves (4). 5) of the second diverter control and the control pressure branch (1) and of the discharge line (12), the spaces behind the valve plug (4, 5) of the second and the diverter control are communicated via the throttling elements (13, 14) to the control space (16) a third stupid control valve (15). Wiring according to claim 1, characterized in that the spaces (8, 9) below the valve plug (4, 5) of the second stage of control are communicated via the Škrtiol elements (13, 14) to the control space (16) of the third stage valve (15) management. 5 DRAWINGS