DE2759900C2 - Check valve with damping device - Google Patents

Description

The invention relates to a check valve with a damping device according to the preamble of the claim 1.

Such a check valve is disclosed in DE-AS 10 43 737. It is used to reduce pressure surges when Avoid switching water pressure pumps on and off. In addition, this check valve can take effect in the event of pipe bursts if these occur on one side in the pipe system. Against it the known check valve remains open when a pipe rupture occurs on the outlet side.

In DE-OS 24 15 795 a hydraulic supply circuit for a working cylinder is described which is secured against hose breakage. For this purpose, a slide valve is used to control the working cylinder, which has two servo pistons moving the spool in opposite directions, one of which applies the pressure in the supply line on the inlet side directly via the control gap is, while the other is acted upon according to the pressure drop at a measuring throttle. This well-known The device is only suitable for monitoring relatively short cable strands, otherwise long measuring lines are used necessary. The line system itself must also be modified by installing measuring throttles.

In DE-OS 20 13 681 a quick shut-off valve is also described, which one the closure piece includes forcibly moving, double-acting servo-cylinder. The two working spaces of this cylinder are operated by an elaborate arrangement of mechanical valves and electromagnetically Valves depending on the pressure difference between the inlet and outlet side of the valve with Pressure is applied, so that the valve as a whole both in the case of an inlet-side pipe rupture as well as in the case of a The outlet pipe rupture closes normally held in the open position, the force of which has to be overcome during the closing process. Even the closure piece has no profiling. Finally, the external auxiliary valves must be independent be adjusted by each other, so that one has an expensive and complicated facility overall. In DE-OS 21 03 948 a control valve is described which, when the pressure on the inlet side increases first the flow cross-section progressively reduced and finally the control piston closes this completely Valve is connected to a damper piston that controls the movement of the control piston in the direction of to dampen its closed position.

The present invention is intended to further develop a check valve according to the preamble of claim 1 that it is not only in the case of a pipe break on the inflow side, but also in the case of a pipe break on the The downstream side automatically goes into the closed position and thus blocks a defective wiring harness.

This object is achieved according to the invention by a check valve according to claim 1.

In the event of an accident-related quick-action closure, the check valve according to the invention is used both in the Shutting off the inlet side and also when shutting off the outlet side prevents a pressure surge in the line system The check valve according to the invention achieves this with a very simple design without external auxiliary devices. It is therefore characterized by high functional reliability and very low maintenance requirements and is also very inexpensive to manufacture.

With the development of the invention according to claim 2 it is achieved that under normal operating conditions the outlet parts of the bypass line are tightly sealed in the end wall of the actuating piston cylinder is, the actuating piston under these conditions only on the one between the ring projections Annular surface is acted upon with the inlet-side pressure, while its entire back over the interior of the actuating piston cylinder is acted upon by the pressure prevailing at the valve outlet.

The invention is illustrated below with reference to the drawing, in which an exemplary embodiment is shown schematically is explained in more detail. The drawing shows an axial section of a check valve of the housing type of a corner valve.

In the illustrated embodiment, the valve housing 1 essentially contains a valve inlet 2, a valve outlet 3, a housing seat surface 4 and a housing neck which is coaxial with the valve inlet 2 5 to accommodate the inner parts, which are combined to form an installation kit, which is inserted as a whole in the housing neck 5 can be used. The main components of this installation kit are a housing insert 6 with an axial bore 7, a piston rod 8 guided longitudinally displaceably in the axial bore and one at the lower end of the piston rod attached shut-off body 9. The housing insert 6 is equipped with a valve closure 10, which acts as a flange cover is formed, firmly connected with the aid of a screw connection, not shown (at 11). In the position of use of the valve, the valve inlet 2 points approximately vertically downwards.

At the rear end of the piston rod 8, a piston 12 is attached, which in the last phase of Non-contact closing movement, d. H. with game in one

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Damping cylinder 17 is immersed The shut-off body 9 is designed with a profile 15 protruding from its sealing surface 14 in the shape of a truncated cone .

The interior 18 of the housing insert 6 is connected to the interior of the valve housing 1 via channels 19. In the course of the connecting channels, suitable screen bodies 20 are arranged, which prevent the penetration of To prevent dirt in the room 18.

With normal flow of the operating medium, the shut-off body 9 is caused by the dynamic flow pressure held in the open position. It then rests with its stop surface 21 on a correspondingly designed one Stop surface of the housing insert 6. The interior of the valve housing 1 and also the interior 18 of the housing insert 6 are filled with the operating medium and are under the pressure of the same. A mechanical guidance of the shut-off body is only on the piston rod 8 in the axial bore of the housing insert 6 given. This smooth sliding ensures that with pressure equalization between Valve inlet 2 and Ventilaastritt 3 the shut-off body by its own weight and the weight of it connected parts can automatically fall into the closed position. This creates an enlargement in the interior space 18 the filling volume, which is compensated by the fact that operating medium flows in through the channels 19, so that no pressure drop can occur.

On the rear side of the damping piston 12 there is an actuating piston 25 with, in comparison to the shut-off element 9 arranged larger diameter, which is attached to a piston rod 26 in a bore of the valve closure 10 is axially displaceably guided. The actuating piston 25 slides on the inner wall of the housing insert 6th

On the actuating piston 25, two concentric ring sealing surfaces are provided on the inside, which on two corresponding concentric ring lugs 27 on the valve closure 10. The one between the rings 27 and the actuating piston 25 lying annular space 28 is via a bypass line 29 with the valve inlet 2 connect.

Under normal operating conditions and also in the event of a pipe break in the supply line, the The actuating piston 25 is held in the rest position shown in the drawing by a retaining spring 30. The the outer closure is formed by a hood 31 which is fastened to the valve closure 10 by a screw connection. the for the force application of the operating medium on the actuating piston 25, the effective area in the pressure medium space is dimensioned in such a way that that under normal operating conditions that from the pressure difference between valve inlet 2 and valve outlet 3 resulting force and the dead weight of the actuating piston 25, the counterforce of the retaining spring 30 can not overcome.

The sealing of the annular space on the ring lugs 27 prevents a under normal operating conditions Leakage to valve outlet 3.

The function of the check valve is as follows:

If a pipe breaks on the outlet side of the check valve, the pressure drop is increased significantly and a larger amount of media flows through the valve. As a result of the higher flow velocity the pressure loss in the valve increases, i. H. in valve inlet 2 the pressure is much higher than in Valve outlet 3. The pressure prevailing in the valve inlet 2 is transferred to the bypass line 29

Transfer back of the actuating piston 25, on its on the opposite side, the lower pressure on the valve outlet side is effective The resulting from the pressure difference The resulting force pushes the actuating piston 25 and thus the shut-off body 9 into the closed position. With the Immersion of the damping piston 12 in the cylinder 17 is also the closing movement here muffled

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Claims (3)

Patent claims: 1. Non-return valve with damping device, in particular for securing in the event of a pipe break, with axial freely movable shut-off body, which is held in the open position by the flow medium has a profile protruding from its sealing surface and one located on the valve outlet side with a piston (damping piston) Damping cylinder is firmly connected, thereby characterized in that in the axial extension of the damping piston (12) an independently movable Adjusting piston (25) with a larger diameter in comparison to the shut-off body (9) in a cylinder is arranged and that the pressure medium chamber closed off on its rear side by the actuating piston (25) is connected to the valve inlet (2) via a bypass line (29) 2. Check valve according to claim 1, characterized in that the actuating piston (25) on two concentric Ring projections (27) on the inside of the valve closure (10) with corresponding Sealing surfaces rests and that the bypass line (29) enclosed in the by the annular projections (27) Pressure medium space opens. 3. Check valve according to claim 2, characterized in that on the actuating piston (25) a Retention spring (30) engages, which this in its starting position under normal operating conditions holds on.