GB2316997A

GB2316997A - Improvements in valves

Info

Publication number: GB2316997A
Application number: GB9618685A
Authority: GB
Inventors: Walter Maag
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-09-06
Filing date: 1996-09-06
Publication date: 1998-03-11
Also published as: GB9618685D0; EP0828025A3; EP0828025A2

Abstract

A valve for use in a pulper dirt trap comprises a plate or flap (8) which is pivotally mounted on a valve housing (1), a hydraulic or pneumatic ram (16) for moving the plate (8) between open and closed positions, a seal (11) in the form of a beading of V-shaped cross-section located between the housing (1) and the plate (8) in the closed position of the valve, a retaining hook (22) for releasably retaining the plate (8) in the closed position and a hydraulic or pneumatic ram (26) for operating the retaining hook (22).

Description

2316997 Title: IMPROVEMENTS IN VALVES This invention relates to valves and

is particularly, but not exclusively, concerned with valves for use in the paper maldng industry.

In the pulping of waste paper for use in re-cycling in the paper maldng industry, dirt is collected in a pulper dirt trap and this must be cleared periodically to prevent the dirt trap from becoming clogged. In the past, slide valves have been used but these cause problems because grit contained in the dirt and other waste acts as a grinding paste thereby causing excessive wear of the valve and calling for frequent servicing and replacement of the valve.

Because the system operates at pressures of up to 6 Bar, it has not been possible to use conventional flap valves instead of slide valves because the pressure would simply force the flap valves off their seatings. This is undesirable because not only would the pressure then be lost but there would be considerable wastage of water used in the process.

The present invention aims to provide a valve which overcomes the problems of existing valves.

According to the invention, there is provided a valve for use in a pulper dirt trap, said valve comprising a plate or flap pivotally mounted on a valve housing, means for moving the plate or flap between open and closed positions, a seal located between the housing and the plate or flap in the closed position of the valve, means for releasably retaining the plate or flap in the closed position and means for operating the retaining means.

Preferably, the means for moving the plate or flap between the open and closed positions comprises a hydraulic or pneumatic ram.

2 The seal desirably takes the form of a strip of resilient material which may be secured, for example by means of a suitable adhesive, to the valve housing or located in a groove at or adjacent to the periphery of the plate or flap. The seal is preferably made of rubber or of a resilient plastics material.

The means for releasably retaining the plate or flap in the closed position desirably comprise a pivotally mounted hook which is movable between a first position in which it engages the plate or flap to hold said plate or flap in a closed position and a second position in which it is free of the plate or flap to permit said plate or flap to move to the open position of the valve. The means for operating the retaining means may comprise a pneumatic or hydraulic ram.

The invention will now be further described, by way of example, with reference to the drawings, in which:- Fig. 1 is a side elevation of one embodiment of a valve according to the invention; and Fig. 2 is a cross-section, to an enlarged scale, through a seal for use in the valve shown in Fig. 1.

Referring to the drawings, the valve according to the invention is adapted to be fitted to the open lower end of a housing 1 for a pulper dirt trap for use in apparatus for pulping waste paper. The upper end of the housing 1 is provided with a flange 2 for securing the housing to the remainder of the pulping apparatus (not shown).

The housing 1 is substantially circular in cross-section and its lower end is inclined and provided with a flange 3 which is welded or otherwise secured to said lower end of the housing. The flange 3 is provided at one point on its periphery with a first lug 4 and at a substantially diametrically opposite point with 3 a second lug 5. One arm of a U-shaped bracket 6 is pivotally mounted on the lug 4 by means of a pivot pin 7 and a lug 9 formed on a plate 8 is pivotally mounted on the other arm of the bracket 6 by means of a pivot pin 10.

One arm 12 of a seal 11, in the form of a beading of V-shaped crosssection, as 5 shown in Fig. 2, and made of a resilient material such as rubber or a suitable plastics material, is secured by a suitable adhesive to the flange 3 around the edge of the opening which is closable by the plate 8. The other arm 13 of the beading 11 is engageable with the plate 8 when said plate is in the closed position of the valve. In this position of the plate, the beading 11 is compressed to provide an efficient seal between the plate 8 and flange 3. Further, the beading is so arranged that the open side of the W" faces inwardly so that pressure in the housing 1, when the valve is closed, will tend to force the arms 12 and 13 apart and hence will increase the sealing effect of the seal.

A trunnion 14 is secured to the plate 8 and is pivotally connected by a pivot pin 15 to the piston 17 of a hydraulic or pneumatic ram 16, the cylinder 18 of which is pivotally mounted by a pivot pin 19 to a bracket 20 secured, such as by welding, to the side of the housing 1. By operating the ram in one direction, the plate 8 can be moved from the closed position shown in Fig. 1 to an open position (not shown) and by operating the ram in the opposite direction, the plate can be moved from the open position back to the closed position shown in Fig. 1 of the drawings.

Since the pulping apparatus operates at comparatively high pressures of up to 6 Bar, the ram 16 does not operate with sufficient force to ensure that the plate 8 will remain in the closed position of the valve. Retaining means in the form of a hook 22 are therefore provided, the hook being pivotally mounted on the lug 5 by means of a pivot pin 23. As shown in Fig. 1, the hook 21 is substantially Ushaped and is adapted to engage over the rim of the plate 8 opposite to the pivotal mounting of the plat on the lug 4. A roller 24 is rotatably mounted in the arm 4 of the hook which is engageable with the plate 8 to facilitate engagement of the hook with the plate and disengagement therefrom. A trunnion plate 25 is secured to the hook 22 and is connected by a pivot pin 30 to the piston 27 of a hydraulic or pneumatic rain 26, the cylinder 28 of which is pivotally mounted by a pivot pin 29 to a bracket 21 secured, such as by welding, to the side of the housing 1 in a similar manner to the bracket 20.

By operating the ram 26 in one direction, the hook 22 can be moved from the position shown in Fig. 1 of the drawings to a position in which it is clear of the plate 8 so that said plate can then be moved by the ram 16 to the open position of the valve. Once the plate has been returned by the ram 16 to the closed position, the hook 22 can be returned, by the ram 26, to the position shown in Fig. 1 of the drawings in which it is effective to retain the plate 8 in the closed position of the valve. The hook is thus effective to keep the valve closed even with the elevated pressures created in the pulping apparatus.

The housing 1 is provided in its side wall with a sight glass 31 in order that the interior of the pulper dirt trap can be viewed for the accumulation of dirt in the housing. However, the valve may be arranged to be opened automatically at predetermined time intervals ranging, for example, from between ten minutes and up to four hours by sequential operation of the rams 26 and 16.

The valve according to the invention represents a considerable improvement over existing valves and calls for only minimal maintenance.

It should be noted that the invention is not restricted to the abovedescribed embodiment but variations and modifications may be made without departing from the scope of the invention. For example, the plate 8 may be provided with a groove at or adjacent to its periphery in which one arm of the seal 11 is located and secured, the other free arm of the seal then being engageable with the flange 3 in the closed position of the plate 8.

Claims

1. A valve for use in a pulper dirt trap, said valve comprising a plate or flap pivotally mounted on a valve housing, means for moving the plate or flap between open and closed positions, a seal located between the housing and the plate or flap in the closed position of the valve, means for releasably retaining the plate or flap in the closed position and means for operating the retaining means.

2. A valve according to claim 1, wherein the means for moving the plate or flap between the open and closed positions comprises a hydraulic or pneumatic ram.

3. A valve according to claim 1 or claim 2, wherein the seal comprises a strip of resilient material.

4. A valve according to claim 3, wherein the seal is secured to the valve housing.

5. A valve according to claim 4, wherein the seal is secured to the valve housing by an adhesive.

6. A valve according to claim 3, wherein the plate or flap is provided adjacent to its periphery with a groove and wherein the seal is located in the groove.

7. A valve according to any one of claims 3 to 6, wherein the strip is of substantially V-shaped cross-section.

8. A valve according to any one of the preceding claims, wherein the seal is made of rubber or a resilient plastics material.

6

9. A valve according to any one of the preceding claims, wherein the means for releasably retaining the plate or flap in the closed position comprise a pivotally mounted hook which is movable between a first position in which it is engageable with the plate or flap to hold said plate or flap in the closed position and a second position in which it is free of the plate or flap to permit said plate or flap to move to the open position of the valve.

10. A valve according to claim 9, wherein the hook is pivotally mounted on a flange which forms an extension of the valve housing.

11. A valve according to claim 9 or claim 10, wherein the hook is provided with a roller which is arranged to engage with the plate or flap when said plate or flap is in the closed position and the hook is being moved from the second position to the first position.

12. A valve according to any one of the preceding claims, wherein the means for operating the retaining means comprise a hydraulic or pneumatic ram.

13. A valve according to any one of the preceding claims, wherein the valve housing is provided with a sight glass.

14. A valve according to any one of the preceding claims, wherein the valve is provided with means for moving the plate or flap from the closed to the open position at predetermined time intervals.

15. A valve substantially as described herein with reference to the drawings.