GB2144522A

GB2144522A - Cap-type slide valve

Info

Publication number: GB2144522A
Application number: GB08419591A
Authority: GB
Inventors: Helmut Bercx
Original assignee: Waeschle Maschinenfabrik GmbH
Current assignee: Waeschle Maschinenfabrik GmbH
Priority date: 1983-08-02
Filing date: 1984-08-01
Publication date: 1985-03-06
Also published as: GB8419591D0; DE3327901A1; JPS60106734A; NL8402311A

Abstract

A cap-type slide valve for bulk material conduits and containers comprises a housing having a circular opening which can be closed by a cap member (3) which is mounted pivotally in the housing, wherein the edge of the cap member (3) which projects beyond the edge of the opening bears against a fluid-actuated sealing arrangement which is held in a seating ring (5) and which comprises a stack of resilient annular discs (6a to 6i), the inside diameter of which is stepped to correspond to the contour of the cap member (3). <IMAGE>

Description

SPECIFICATION Cap-type slide valve The invention relates to a captype slide valve for bulk material conduits and containers, comprising a housing having a circular opening which can be closed by a cap member mounted pivotally in the housing, wherein in the closed condition the edge of the cap member which projects beyond the edge of the opening bears against a fluid-actuated sealing arrangement which is mounted in a sealing ring.

A cap-type slide valve of that kind is disclosed in German patent specification No 2 607 686. In the open condition, the cap member, being pivoted to the side, permits a flow of bulk or loose material to pass through unimpededly. When the closure operation is initiated, the cap member gradually covers over the free flow cross-section through the valve. When that occurs, the lower edge of the seating ring and the leading edge of the cap member form a cutting gap which is in the region of 0.5 mm in width. Any particles which block the closure operation are cut through by that arrangement. The cap-type slide valve can therefore be closed in a full flow of bulk material through the valve.The sealing arrangement comprises a hollow, inflatable annular seal which, while having the advantage over other sealing means which constantly bear against the cap member as it closes, of having a considerably lower rate of wear and, by virtue of its width, making it possible to enclose smaller particles of material, does however suffer from the disadvantage that it is not suitable for higher temperatures and cannot be rapidly put into use in the form of a special design if replacement is required. Therefore, the known cap-type slide valve is unsuitable or is suitable only within limitations, for certain kinds of pneumatically conveyed bulk or loose materials which are transported in the hot condition (for example ash and slag) and/or which are highly abrasive (for example coarse and fine coal).

The invention is based on the problem of providing a cap-type slide valve of the general kind set forth in the opening part of this specification, wherein the parts of the sealing arrangement which are subjected to wear are of a simple geometrical form and may comprise different materials according to the various conditions of use involved.

In accordance with the invention, that problem is solved in that the sealing arrangement comprises a stack of resilient annular discs, the inside diameter of which is stepped to correspond to the contour of the cap member.

Such annular disc sealing means can be very easily produced without special equip ment, and possibly also using the equipment of an operating or site workshop. The annular discs may comprise rubber-elastic materials, plastic material, steel, bronze or other materials which are suitable for the respective situation of use, while different materials may also be used within the same stack. It is also advantageous that the inner edges of the individual annular discs form a stepped labyrinth configuration on the surface of the cap member, which produces a stepwise reduction in pressure so that pressure differences of more than 10 bars are admissible and a pressure surge resistance of up to over 20 bars can be achieved. In addition, the hollow spaces between the individual steps can accommodate small particles of bulk material so that they do not detrimentally affect the sealing action.

The annular discs are advantageously disposed parallel to the plane containing the opening. The sealing effect is then produced by axial displacement at least of the inward parts of the annular discs.

A preferred embodiment provides that the annular discs are clamped at their outside periphery in a holding means and that the seating ring has an annular groove which is concentric with respect to the opening and which contains an actuating means that acts on the free large face of the annular disc having the smallest inside diameter.

The actuating means may comprise an annular piston which can be subjected to a pressure, from the bottom of the annular groove. The large area of the annular piston gives the advantage that the control pressure for activating the sealing arrangement is only about two thirds of the pressure obtaining in the pressure chamber or space which is to be sealed off. As compressed air is generally used, there is therefore no need for a separate compressed air system for actuating the sealing arrangement.

A first development of that embodiment is characterised in that the annular groove is of rectangular or square cross-section and that a resilient compensating pad or cushion is disposed between the annular piston and the annular disc of smallest inside diameter. The annular pad compensates for the differences in travel caused by the annular discs being clamped at their outside, when they are displaced by means of the annular piston.

In a second development, the functions of the annular piston and the compensating pad are combined. In that arrangement, the annular groove is of an undercut trapezoidal crosssection and the annular piston comprises a rubber-elastic material.

An embodiment which is particularly suitable for high operating temperatures is characterised in that the actuating means comprises at least two symmetrically disposed elbow lever arrangements which bear against the bottom of the groove, each of said arrangements being actuable by way of a piston rod which extends into the annular groove from the exterior and which engages the elbow joint, and bearing with the free end of its second elbow lever by way of pressure equalisation members against the large face of the annular disc having the smallest inside diameter. In that embodiment, all parts may comprise metal materials.

In another embodiment, the annular discs are radially compressible and are enclosed at their outside periphery by a rubber-elastic annular sleeve which can be subjected to pressure from the free side thereof. The annular discs themselves may selectively comprise rubber-elastic materials or metal materials. In the latter case, the radially compressibility is produced by means of at least one slot in each annular disc, with the annular discs being installed with the slots displaced relative to each other in the peripheral direction.

Embodiments selected by way of example of a cap-type slide valve according to the invention are shown in diagrammatically simplified form in the drawings in which: Figure 1 shows a view in section through a first embodiment of the slide valve, Figure 2 shows the sealing region A of the slide valve shown in Fig. 1, on an enlarged scale, Figure 3 shows the sealing region of a second embodiment of the slide valve, Figure 4 shows the sealing region of a third embodiment, and Figure 5 shows the sealing region of a fourth embodiment of the slide valve.

The cap-type slide valve shown in Fig. 1 is flanged on to the lower end of a container cone portion 1 of which only part is shown, and comprises a housing 2a, 2b and 2c in which a spherical cap member 3 is mounted pivotally about an axis 4 between the open position shown in dash-dotted lines and the closed position shown in solid lines. In the closed position, the cap member 3 bears with its edge region against a sealing arrangement which is fitted to and into a seating ring 5.

Fig. 2 shows the construction of the sealing arrangement. The sealing arrangement comprises a stack of resilient circular annular discs 6a to 6i which can comprise rubber, plastics material or metal, depending on the situation of use and in particular in dependence on the temperature resistance required. The inside diameter of the annular discs 6a to 6i is stepped to correspond to the contour of the cap member 3. Slide films or foils comprising for example Teflon (not shown) may possibly be disposed between the individual annular discs.The stack of annular discs is clamped at its periphery into an annular holding means which in the embodiment illustrated essentially comprises a ring 7 which engages around the outside periphery of the stack and which partially engages by means of a shoulder 7a over the annular disc 6i which is of largest inside diameter, and is fixedly connected to the ring 5 by means of screws 8.

The ring 5 also includes an annular groove 9 of square or rectangular cross-section. A bore 10 which goes to the exterior communicates with the bottom of the groove, for the supply of a pressure fluid. The annular groove 9 accommodates an annular piston 11 which is guided in a sealed manner by means of Orings 1 2a and 1 2b. The annular piston 11 bears against the large face, which is on the top, of the uppermost annular disc 6a of the smallest inside diameter, by way of an annular, resilient compensating pad or cushion 1 3.

When pressure fluid is introduced by way of the bore 10, the annular piston 11 now brings the annular discs 6a to 6i into a condition of bearing against the cap member 3, by way of their inward front edges. The resilient flexing of the annular discs 6a to 6i which occurs in that situation acts as a return force after the annular piston 11 is relieved of pressure. The pad or cushion 1 3 accommodates the differences in travel movement which occur by virtue of the annular discs being clamped at one side.

Fig. 3 shows an embodiment which does not require such a (separate) compensating pad. With the remainder of the construction being the same, the annular groove is of a substantially trapezoidal cross-section which increases in width towards the bottom of the groove, and the annular piston 11 a comprises a rubber-elastic material. When pressure is applied by way of the bore 10, there is no noticeable axial displacement of the annular piston 11 a, but, by virtue of the elasticity of the material used, the end face of the piston, which bears against the annular disc 6a, takes up a spherically bulged configuration so that the annular discs are also urged resiliently downwardly.

The sealing arrangement shown in Fig. 4 is suitable in particular for cap-type slide valves which are intended for use at high temperatures for the sealing arrangement includes only components consisting of metal. The annular discs which comprise for example steel or bronze and which are considerably thinner and wider because of their higher spring constant, are integrally screwed together and to the ring 5, at their outside periphery. For the purposes of producing axial deformation of the annular discs until they bear against the cap member 3, the apparatus has an elbow lever actuating means in which the first elbow lever 14 bears by way of a mounting against the bottom of the groove 9a while the second elbow lever 1 5 bears against the upper large face of the uppermost annular disc 6a, by way of a fork 1 6 tiltably mounted at the free end of the second elbow lever 15, an inner pressure member 1 7a, an outer pressure member 1 7b and four mutually concentric rings 1 8a to 1 8d.By virtue of suitable radii of curvature of the surfaces of those components which are in contact with each other, the arrangement provides that line contact occurs in each case so that the members 1 6 to 18 can tip relative to each other, with a low level of friction, in order to compensate for the different travel lengths involved. The sealing arrangement is actuated by way of a piston rod 19 which is extended out of the seating ring 5 and the end face of which presses against a roller 21 mounted on the spindle or shaft of the elbow joint 20.

In the embodiment illustrated in Fig. 5, the stack comprising annular discs 6a to 6i which are resilient in the radial direction is disposed completely in a groove 22 in the seating ring 5. The stack is enclosed by a resilient annular sleeve 23 which can be subjected to the action of a pressure fluid by way of a bore 24 which opens into the bottom of the groove.

The annular discs 6a to 6i may comprise rubber-elastic materials or slotted metal annular discs. If there is a perceptible difference in pressure between the two spaces or chambers which are separated from each other by the cap member 3, then in that case the annular discs are to be stacked with mutually displaced slots.

Claims

1. A cap-type slide valve for bulk material conduits and containers, comprising a housing having a circular opening which can be closed by a cap member mounted pivotally in the housing, wherein the edge of the cap member which projects beyond the edge of the opening bears against a fluid-actuated sealing arrangement which is mounted in a seating ring, wherein the sealing arrangement comprises a stack of resilient annular discs, the inside diameter of which is stepped to correspond to the contour of the cap member.

2. A cap-type slide valve according to claim 1 wherein the circular annular discs are arranged parallel to the plane which contains the opening.

3. A cap-type slide valve according to either of claims 1 and 2 wherein the annular discs are clamped at their outside periphery in a holding means and the seating ring has an annular groove which is concentric with re spect to the opening and which contains an actuating means that acts on the free large face of the annular disc having the smallest inside diameter.

4. A cap-type slide valve according to claim 3 wherein the actuating means comprises an annular piston which can be acted upon by a pressure, from the bottom of the annular groove.

5. A cap-type slide valve according to claim 4 wherein the annular groove is of square or rectangular cross-section and a resilient, annular compensating pad is arranged between the annular piston and the annular disc having the smallest inside diameter.

6. A cap-type slide valve according to claim 4 wherein the annular groove is of an undercut trapezoidal cross-section and that the annular piston comprises a rubber-elastic ma teal.

7. A cap-type slide valve according to claim 3 wherein the actuating means comprises at least two symmetrically disposed elbow lever arrangements which bear against the bottom of the groove, each of said arrangements being actuable by way of a piston rod which extends into the annular groove from the exterior and which engages the elbow joint, and bearing with the free end of its second elbow lever by way of pressure equalisation members against the large face of the annular disc having the smallest inside diameter.

8. A cap-type slide valve according to claim 1 or claim 2 wherein the annular discs are radially compressible and are enclosed at their outside periphery of a rubber-elastic annular sleeve which can be pressure-actuated from its free side.

9. A cap-type slide valve according to claim 1 substantially as herein described.

10. A cap-type slide valve substantially as herein described with reference to the accompanying drawings.