GB2043216A

GB2043216A - Improved slide valve

Info

Publication number: GB2043216A
Application number: GB8005411A
Authority: GB
Original assignee: Elektrowatt AG
Current assignee: Siemens Building Technologies AG
Priority date: 1979-02-28
Filing date: 1980-02-18
Publication date: 1980-10-01
Also published as: SE8000710L; CH635909A5; DE3005006A1

Abstract

A slide piston (19) is displaceable by means of a tappet (32) in a valve sleeve (17) provided with radial, through-going passages (18). In order to be able to tolerate a deviation in the coaxiality between the tappet (32) and the slide piston (19), even with the minimum clearance between the outside diameter of the slide piston (19) and the inside diameter of the valve sleeve (17), without involving the risk of jamming of the slide piston (19) in the valve sleeve (17), the tappet (32) is connected to the slide (19) by means of a resilient connection (37, 38). At one end, the slide (19) comprises an annular sealing surface (25) which, in the closed position, rests tightly on a valve seat (26) disposed at one end of the valve sleeve (17). <IMAGE>

Description

SPECIFICATION Improved slide valve The invention relates to a valve with a slide which is displaceable longitudinally in a valve sleeve by means of a tappet.

It is known that in such valves a certain clearance has to be provided between the external diameter of the slide and the internal diameter of the valve sleeve in order to avoid jamming of the slide in the valve sleeve in case the valve tappet is not guided precisely coaxially to the valve sleeve - which is practically always the case as a result of inevitable manufacturing tolerances. Therefore such valves were hitherto scarcely used as shut-off valves but only as regulating valves because the clearance to be provided always led to a certain leakage.

It is therefore an object of the invention to provide a valve of the kind initially referred to wherein the clearance between slide and valve sleeve is considerably smaller and so that the valve can also be made more suitable as a shut-off member, without involving the risk ofjamming of the slide in the valve sleeve.

The present invention is a valve having a slide displaceable longitudinally in a valve sleeve by means of a tappet, and in which the tappet is connected to the slide by means of a resilient connection.

The present invention is also a valve having a slide piston displaceable longitudinally by means of a tappet in a valve sleeve with radial through-going passages, and in which disposed in the region of one end of the valve sleeve is an annular valve seat which cooperates with an annular sealing surface formed on the facing end of the slide piston, and the tappet is connected to the slide for tumbling by means of a resilient connection.

An embodiment of the present invention wil now be described, by way of example, with reference to the accompanying drawing, the single Figure of which is a diagrammatic section through the important components of a valve according to the present invention.

Of the valve 10 illustrated, there is seen in the drawing that part of its housing 11 which lies between an inlet chamber 12 and an outlet chamber 13. In a partition 15 provided with passages 14 there is a recess 16 into which one end of a tubular valve sleeve 17 is tightly let. In the region of its other end, the valve sleeve 17 is provided with a number of through-going bores 18 extending radially (only two of these can be seen in the Figure), which are disposed with peripheral spacing apart and along a helical line.

A slide piston 19 is mounted for displacement with a sliding fit in the valve sleeve 17. Formed in the slide piston 19 is a first bore 20 which merges, substantially in the longitudinal middle of the slide piston 19, into a bore 23 of smaller diameter which is provided with countersinking 21, 22 at both ends. At the end remote from the bore 23 the bore comprises a conical countersinking 24 so that the slide piston 19 ends at its end adjacent to the bores 18 in an annular, plane sealing surface 25. The sealing surface 25 cooperates with a valve seat 26 which is likewise annular and plane and which is constructed with a flange 28 at the end of a central bore 27.The flange 28, which is firmly screwed, by means of bolts 29, to an annular projection 30 of the valve housing 11, extending inwards between the inlet and outlet chambers 12 and 13 has, in its middle, an annular should 31 which fits precisely in the internal diameter of the valve sleeve 17 and the end of which forms the valve seat 26.

Extending through the bore 27 in the flange 28 and through the bores 20, 23 in the slide piston 19 is the tappet 32. The upper end of the tappet 32, which does not appear in the drawing, is taken out of the valve housing 11 through a wall entrance and there coupled to a servo-drive with which the tappet 32 can be driven in the axial direction. At the lower end appearing in the Figure, the tappet 32 is provided with an axial tapped bore 33 in which a screw 35 provided with a head 34 is screwed. With this screw 35 - with the interposition of an- intermediate member 36 - two spring washers 37, 38 are gripped to the tappet 32 in their middle.The length of the intermediate number 36 is shorter, by a small amount, than the length of the bore 23 including the depth of the two countersinkings 21,22, so that the spring washes 37,38 bear frictionally at the periphery against plane annular surfaces 39,40 of the piston 19 following on the periphery of the countersinkings 21, 22. Passages 41,42 are present in the spring washers 37,38 and establish a flow-connection between the two sides of the slide piston 19.

From what has been said, it follows that the tappet 32 is connected to the slide 19 for tumbling by means of a resilient connection. In addition,this connection is positive in the axial direction (if the springing of the spring washers 37,38 is ignored) but frictional in the radial direction and in the direction of twisting. This connection thus permits a certain eccentricity of the tappet with respectto the slide piston. Even if the axis of the tappet 32 does not coincide precisely with the axis of the slide piston 19, which is guided by the valve sleeve 17, or is not precisely parallel to this, there is no risk of tilting of the slide piston 19 in the sleeve 17.In the closed position illustrated, a satisfactory sealing between the inlet chamber 12 and the outlet chamber 13 is afforded by the sealing surface 25 on the slide piston 19 on the one hand and the valve seat 26 at the shoulder 31 on the other hand, even if the end of the sleeve 17 adjacent to the flange 28 were not sealed off from this (as illustrated). Even if, in the closed position, no constant or only a slight closing force isexerted through the tappet 32, the slide piston 19 is subject to a force acting in the closing direction, that is to say upwards in the Figure - provided there is a pressure drop between the inlet chamber 12 and the outlet chamber 13 - which force is the greater, the larger the diameter of the tappet 32. At both sides of the slide piston 19, the same pressure prevails as in the outlet chamber 13, but the area of the slide piston 19 acted upon by this pressure is greater at the side adjacent to the recess 16.

Claims

1. Avalve having a slide displaceable longitudinally in a valve sleeve by means of a tappet, and in which the tappet is connected to the slide by means of a resilient connection.

2. Avalve as claimed in claim 1, in which the resilient connection comprises at least one spring washer which is coupled to the slide in the region of its periphery and is gripped on the tappet in its middle.

3. A valve as claimed in claim 1, in which the resilient connection comprises two spring washers which are coupled to the slide at the periphery at annular surfaces which are remoted from one another in the axial direction and are gripped on the tappet in their middle.

4. A valve as claimed in claim 3, in which the tappet extends with clearance through the slide and the spring washers bear frictionally against the annular surfaces at the periphery.

5. A valve as claimed in claim 4, in which each spring washer is provided with at least one passage which establishes a flow connection between the two sides of the slide.

6. Avalve having a slide piston displaceable longitudinally by means of a tappet in a valve sleeve with radial through-going passages, and in which disposed in the region of one end of the valve sleeve is an annular valve seat which cooperates with an annular sealing surface formed on the facing end of the slide piston, and the tappet is connected to the slide for tumbling by menas of a resilientconnec- tion.

7. A valve as claimed in claim 6, in which the annular valve seat and the annular sealing surface of the slide piston as plane.

8. A valve as claimed in claim 6, in which the resilient connection is positive in the axial direction but frictional in the radial direction.

9. A valve as claimed in claim 7, in which the resilient connection comprises two spring washers which rest frictionally on plane annular surfaces remote from one another in the axial direction on the slide piston at the periphery and are gripped on the tappet in their middle.

10. A valve as claimed in claim 8, in which the tappet extends with clearance through the slide piston.

11. A valve as claimed in claim 9, in which at least one passage is provided in each spring washer and establishes a flow connection between the two sides of the slide piston.

12. Avalve substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.