GB2056629A

GB2056629A - Hydraulically openable valve

Info

Publication number: GB2056629A
Application number: GB8026149A
Authority: GB
Original assignee: Carl Schenck AG
Current assignee: Carl Schenck AG
Priority date: 1979-08-10
Filing date: 1980-08-11
Publication date: 1981-03-18
Also published as: JPS5920070B2; DE2932523C2; GB2056629B; DE2932523A1; CH649360A5; JPS5628374A

Abstract

An hydraulically openable valve operated by two way pilot valve 14 comprises a spring loaded piston 5 which coacts with seat 4 to prevent flow from an inlet connection 12 to an outlet 3 is characterised in that pressure fluid reaches spring chamber 9 via passages 16 and 16' and also by controlled clearances 11 between the walls of the piston 5 and the base 2 in which it slides. Pressure fluid passes from the inlet connection 12 to act on the closing face of the piston 5 via a controlled clearance 10. A variable throttle 15 may be provided in the exhaust line to control the speed of opening. <IMAGE>

Description

SPECIFICATION An hydraulically openable valve The invention relates to an hydraulically openable valve, more particularly a non-return valve, having a base member which has a pressure medium channel, a valve body arranged so as to be longitudinally movable in the pressure medium channel of the base member and a valve seat arranged in the pressure medium channel.

With known hydraulically openable valves surge cylinders are provided which open the actual valve.

Thus additional control connections for the surge cylinder are necessary. The known valves open the pressure line to the load suddenly as soon as the surge piston raises the valve piston. Thus the build-up in pressure on the load is also sudden or in surges. A further known hydraulically openable non-return valve operates in two stages. In the first instance a fairly small valve is opened by surge cylinder and subsequently the main piston of the valve opens suddenly.

The present invention seeks to create an hydraulic ally openable valve which-operates without surge cylinders which makes it possible to connect a pressure medium continuously and build up pressure continuously at a load and thus eliminates surges due to initial connection. This according to the invention, there is provided an hydraulicaily openable valve comprising a base member, a pressure medium channel in the base member, a pressure medium channel in the base member, a valve seat in the pressure medium channel and a valve body in the pressure medium channel co-operating with the valve seat wherein the pressure medium channel comprising a valve bore of relatively large diameter for receiving the valve body and a bore of smaller diameter for outlet of pressure medium and connected coaxially to the relatively large valve bore to form a valve seat therebetween, wherein an annular channel surrounds the valve bore to subdivide it into two parts and is connected to the source of pressure medium, wherein the valve body is of piston form with a conical end face co-operating with the valve seat and wherein a two way valve is provided for selectively connecting the chamber between the piston and the end of the relatively large diameter bore to the source of pressre medium orto a pressure container.

The invention will now be described in greater detail, by way of an example with reference to the drawings, the single figure of which shows schematically one form of an hydraulically openable nonreturn valve according to the invention.

A valve bore 2 of relatively large diameter is located in a base member 1 together with a bore 3 having a smaller diameter, leading to the load and connected coaxially to the larger bore 2. The opening of the smaller bore into the large valve forms a valve seat 4. A valve piston 5 is mounted so as to be longitudinally movable in the large valve bore 2. The valve piston 5 has a flat end face 6 and a conical face 7 (valve cone) which co-operates with the valve seat 4 and seals the smaller valve bore 3 so as to be pressure-medium-tight.

The valve piston 5 is pressed on to the valve seat 4 by a spring 8 engaging the end face ofthe valve piston. The valve spring 8 is located in the valve spring chamber 9 formed by the end face 6 of the valve piston 5 and the larger valve bore 2. It is supported on the base of the larger valve bore 2 or on the base member 1. The valve spring may be settable for the purpose of adjusting to different operating conditions and is exchangable.

The annular clearness 10 and 11 present between the valve piston 5 and the base member 1 form throttle clearances which have a predetermined throttling action. The functioning of the valve, its opening speed for example, may be affected by the size of the throttle clearances. An annular chamber 12 is arranged coaxially of the valve bore 2 and subdivides the valve bore into two portions. The annular chamber 12 is connected to a pump 13 for supply of pressure medium. The annular chamber 12 is connected via the throttle clearances 10 and 11 to the valve spring chamber 9 and a chamber 18 which is formed by the valve cone 7 at the end of the larger bore 2. The annular chamber 12 is also directly connected to the valve spring chamber 9 by means of the lines 16 and 16' as well as by means of a two-way valve 14.

If the two-way valve 14 is switched over (shown in broken lines) it separates the pipes 16 and 16' and the annular chamber 12 from the valve spring chamber 9 and connects the valve spring chamber9 to a pressure medium supply container 17 via a settable throttle valve 15. By setting the throttle ? 5, the opening speed of the valve may be controlled.

With a closed valve, the valve piston 5 closes the smaller valve bore 3, so as to be pressure-mediumtight, with its conical end face 7. The pressure medium coming from the pump 13 cannot reach the load. The pipes 16 and 16' are connected together by means of the two-way valve 14. The same pressure prevails in the annular chamber 12, the valve spring chamber 9 and the chamber 18. A force which comprises the spring force of the valve spring 8 and the force arising from the surface of the smaller valve bore and the pump or system pressure acts on the valve piston 5 so as to close the valve.

In order to open the valve, the two-way valve 14 is switched over. Thus the valve spring chamber 9 is separated from the direction connection with the annular chamber 12 and at the same time is connected to the almost pressureless supply container 17 via the throttle 15. Thus the pressure in the valve sprirg chamber 9 is able to be reduced and the valve piston 5 is finally only pressed on to the valve seat 4 with the spring force of valve spring 8. The pressure medium reaching the valve spring chamber 9 via the throttle clearance 11 may flow out through the throttle 15 into the supply container 17.

After switching over, the pressure in the chamber 18 on the valve cone 7 counteracts the spring force of the valve spring 8 on the valve piston 5 and the continuously reducing pressure on the end face 6 of the valve piston. The valve spring 8 and the throttle clearances are so designed that the pressure in the chamber 18 on the annular surface of the valve cone 7 gradually becomes predominant after the valve has been switched over. Thus the valve opens. The pressure in chamber 18 drops due to opening of the valve so that initially only a throughflow which is controlled automatically and is heavily throttled by the annular gap 10 and the opening cross-section of the valve is allowed to pass via the valve bore 3 to the load. Thus an empty load, for example, may be filled.

If the pressure at the load has reached the pressure in chamber 18 and increases further the valve opens more strongly while at the same time the throttling action of the annular clearance 10 is reduced (see the position of the valve cone 7 which is shown in broken lines). However a throughflow throttled by the annular clearance 10 still flows to the load. Only with a further increase in pressure in the load or in chamber 18 and thus compression of the valve spring 8 does the valve piston 5 pass into its maximum open position (shown in chain lines). In this position the entire flow conveyed by the pump 13 flows through the annular channel 12 and the valve bores 2 and 3 and flows unthrottled to the load or the total system pressure is built up.

A surge-free and smooth connection of the pressure medium is ensured by the arrangement de scribed, from a pressure medium supply system to a load, more particularly with large flow cross sections. Thus for example hydraulic cylinders of testing devices which are operated at high system pressures may be switched on safely without samples acted upon by the cylinder being subjected to excessive loads or being damaged. This is true more particularly if the cylinder chambers are empty and first have to be filled. Furthermore freedom from surge is ensured even if the controi valve of the hydraulic cylinder is incorrectly controlled during connection.

Claims

1. An hydraulically openable valve comprising a base member a pressure medium channel in the base member, a valve seat in the pressure medium channel and a valve body in the pressure medium channel cooperating with the valve seat wherein the pressure medium channel comprises a valve bore of relatively large diameter for receiving the valve body and a bore of smaller diameter for outlet of pressure medium and connected coaxially to the relatively large valve bore to form a valve seat therebetween wherein an annular channel surrounds the valve bore to subdivide it into two parts and is connected to the source of pressure medium, wherein the valve body is of piston form with a conical end face cooperating with the valve seat and wherein a two way valve is provided for selectively connecting the chamber between the piston and the end ofthe relatively large diameter base to the source of pressure medium orto a pressure container.

2. An hydraulically openable valve according to claim 1, wherein the chamber between the piston and the end of the relatively large diameter bore houses a compression spring for biassing the valve body against the valve seat.

3. An hydraulically openable valve according to Claim 1 & 2, wherein annular clearances around the piston are constructed as throttles with a defining throttling action between the valve body and the base member in order to achieve a predetermined throughflow.

4. An hydraulically openable valve according to Claim-3 when appendentto claim 2 wherein the size of the throttle clearances, the spring force of the compression spring and the size of the two valve bores are so arranged with respect to each other that the valve opens slowly, when connected to a given supply pressure.

5. An hydraulically openable valve according to any one of claims 1 to 4 wherein a settable throttle is incorporated in the return line between two-way valve and pressure medium container.

6. An hydraulically openable valve according to claim 2, wherein the compression spring is exchangeable or settable.

7. An hydraulically openable valve substantially as described herein with reference to the drawings.