A VALVE

Abstract: A valve comprises rolling diaphragm (7) supported at its outer periphery by an annular support member (8) within which the diaphragm rolls in response to inlet pressure so as to uncover an outlet opening (20) in the support member, thereby to allow the escape of said pressure. Preferably, the diaphragm (7) is annular and is supported at its inner periphery by a guide member (9) that engages on abutment (19) when the outlet opening (20) is closed by the diaphragm, and that guides the diaphragm as it rolls back and opens the outlet opening (20). Preferably, the outlet opening (20) is of reduced width towards that part which is first uncovered by the diaphragm in operation. The valve may include a two part housing (1, 4) with the support member (8) located between the two parts and with the outer periphery of the diaphragm (7) gripped between one part of the housing (4) and the support member (8).

Description: "A VALVE" TECHNICAL FIELD This invention relates to a valve suitable for use in venting gases from an enclosure whilst preventing -pressure variation in the enclosure due to suction on the outlet side of the valve and maintaining enclosure pressure at some predetermined function of atmospheric pressure. DISCLOSURE OF INVENTION It is desirable that an engine crankcaεe breather should vent gases from the crankcaεe to the induction manifold while at th same time preventing suction in the manifold from reducing the pressure in the crankcaεe. A failure to vent gases may result in the expulsion of oil from the crankcaεe while a reduction in the crankcase pressure may draw dirt into the crankcase. An object of the present invention is to provide a valve for use in a crankcase breather to avoid the aforesaid difficulties. A valve according to the invention comprises a rolling diaphragm supported at its outer periphery by an annular support member within which the diaphragm rolls in response to inlet pressure so as to uncover an outlet opening in the support member, thereby to allow the escape of said presure. An advantage of this valve is that it operates substant ally independently of the pressure on the outlet side of the outlet opening. Suction at the outlet opening will simply cause it to be more firmly sealed by the diaphragm. Preferably, the diaphragm is annular and is supported at its inner periphery by a guide member that engages an abutment when the outlet opening is closed by the diaphragm end guides the diaphragm so that it rolls to uncover the outlet opening . DESCRIPTION OF DRAWINGS The invention will be described by way of examlple with reference to the accompanying drawings in which: Figure 1 is an axial section through a valve according to one embodiment of the invention. Figure 2 is an exploded diagram of the valve of Figure 1 without the rolling diaphragm. Figure 3 is an underside plan view of the upper half of the valve housing, of Figures 1 and 2. Figure 4 is an underside plan view of the valve member of Figures 1 and 2. Figure 5 is an axial section through a valve according to another embodiment of the invention. Figure 6 is an exploded diagram of parts of the valve of Figure 5 without the rolling diaphragm. Figure 7 is an underside plan view of the intermediate part of the valve of Figure 5, and Figure 8 is a schematic diagram of an.-engine having a crankcase breather ioncorporating a valve according to the invention. BEST HOPE OF CARRYING OUT INVENTION The valve illustrated in Figures 1 and 2 has a two part housing comprising a lower portion 1 with a cylindrical inlet duct 2 projecting downwards from its base 3, and an upper cover portion 4. A semi-cylindrical formation 5 projects from the side of each housing portion and these formations co-operate to form an outlet duct 6. An annular rolling diaphragm 7 is provided within the valve housing between an outer cylindrical support member 8 and an inner guide member 9. A bead 10 at the outer edge of the diaphragm is held in place in a gallery 11 in the upper end of the support member 8. An annular wall 12 on the underside of the over portion 4 engages the gallery 11 to clamp the bead 10 in place and to locate the support member 8 with its lower end in engagement with a groove 13 in the base 3 of the lower housing portion. A bead 14 at the inner edge of the diaphragm engages a groove 15 in the outer periphery of a disc-shaped portion 16 of the guide member 9. The guide member has downwardly projecting guide fins 17 that engage within the inlet duct 2 to guide vertical movement of the disc-shaped ' portion 16. A compression spring 18 between the housing cover portion 4 and the disc-shaped portion 16 serves to urge the latter into engagement with an annular abutment 19 formed in the base of the lower housing portion 1 around the inlet duct 2. A series of apertures 20 are formed in the wall of the cylindrical support member 8 and are covered by the diaphragm 7 when the guide member 9 engages the abutment 19. However, upwards movement of the diaphragm 7 guided by the guide member at its inner edge causes the diaphragm to roll back on itself and to uncover the apertures 20, thereby allowing communication between the inlet duct 2 and outlet duct 6 . A hole 21 in the cover portion 4 vents the space above the guide member 9 and diaphragm 7 to atmosphere. The strength of the spring 18 determines the pressure at which the valve opens. An important characteristic of this valve is that, when the diaphragm 7 closes the apertures 20, any fall in pressure in the outlet duct 6 below atmospheric will cause the diaphragm 7 to seal the apertures 20 more firmly. The apertures 20 are shaped so that they -are of the reduced width towards their bottoms, thereby giving a progressive initial opening of the aperatures by the diaphragm and a longer initial movement of apertures by the diaphragm and a longer initial movement of the guide member 9 which is thus more easily damped by the spring 18 and air between the diaphragm and the cover portion 4. As illustrated in Figure 2, each aperture 20 is triangular in shape and is orientated with a point lowermost. However, the apertures 20 could also be circular in shape. A typical application in which this feature is important is in an engine crankcase breather where the inlet duct 2 of a valve 30 would be connected to the crankcase 31 and the outlet duct 6 would be connected to the induction manifold 32 of the engine as shown in Figure 8. The valve would then be responsive to crankcaεe pressures above atmospheric and would open at a pressure determined by the characteristics of the spring 18 and area of the guide member 9 nd the diaphragm 7 to vent crankcase gases through the outlet duct 6 to the induction manifold. On the other hand, any suction produced in the induction manifold will produce a sealing action of the diaphragm and will not pass through the inlet duct 2 to the crankcase where it could draw dirt in through ' </ CVil the crankcase seals. An alternative embodiment of the invention is illustrated in Figure 5 to 7 in which the inlet and outlet ducts are arranged coaxially rather than at right angles to one another. The valve housing again comprises two co-operating portions 22,23. The lower portion 22 has a downwardly projecting inlet duct 2 in its base 3 as in the previous embodiment. The upper cover portion 23 has an upwardly projecting outlet duct 24 in its top wall 25. A disc-shaped intermediate member 26 is clamped at its periphery between the two housing portions 22,23. A guide member 9, a cylindrical support member 8, a diaphragm 7 and a spring 18, all exactly the same as in the previous embodiment, are provided within the valve housing and located by a groove 13 in the base 3 of the lower housing portion 22 and an annular wall 27 on the underside of the intermediate member 26 that correspondε to the wall 12 of the previous embodiment. The annular space between the support member 8 and lower housing portion 22 communicates with the outlet duct 24 via apertures 28 formed in the intermediate member 26. A bore 29 vents to atmosphere the space between the guide member 9 and diaphragm 7 and the intermediate member 26. This valve operates in exactly the same manner as the previous embodiment but when the valve is open, the inlet duct 2 communicates with the outlet duct 24 through the apertures 20 and 28.

Claims: CLAIMS 1. A valve comprising a rolling diaphragm supported at its outer periphery by an annular support member within which the diaphragm rolls in response to inlet pressure so as to uncover an outlet opening in the support member, thereby to allow the escape of said pressure. 2. A valve as claimed in claim 1 in which the diaphragm carries a guide member that engages an abutment around an inlet duct when the diaphragm covers the outlet opening. 3. A valve as claimed in claim 2 in which the diaphragm is annular and its inner periphery is connected to the outer periphery of the guide member. 4. A valve as claimed in claims 2 or 3 in which a spring urges the guide member towards the abutment. 5. A valve as claimed in any one of claims 2 to 4 in which the guide member has ribs projecting axially therefrom that engage the inlet duct so as to guide the guide member relative to the abutment. 6. A valve as claimed in any one of the preceding claims in which the outlet opening is of reduced width towards that part which is first uncovered by the diaphragm in operation. 7. A valve as claimed in claim 6 in which the outlet opening is triangular in shape. 8. A valve as claimed in any one of the preceding claims in which there is a plurality of outlet openings around said support member. -gυRatA Ol. ' rl 9. A valve as claimed in any one of the preceding claims which includes a housing comprising two parts between which the support member is located. 10. A valve as claimed in claim 9 in which the diaphragm is located at its outer periphery by cooperation between one part of said housing and the support member. 11. A valve as claimed in claim 9 or 10 in which the two parts of said housing cooperate to form an outlet duct that communicates with said outlet opening and extends transverεly of the support member 12. A valve as claimed in claim 9 or 10 in which each of the two parts of said housing is formed with a duct co-axial with the support member, one of said ducts being an inlet duct and the other being an outlet duct. 13. A valve substantially as herein described with reference to figures 1 to 4 or 5 to 7 of the accompanying drawings. OMPI.

Inventors: WHITEHEAD DAVID ARTHUR, WHITEHEAD, DAVID, ARTHUR
Applicants: MASSEY FERGUSON PERKINS LTD, MASSEY-FERGUSON-PERKINS LIMITED
Application year: 1983
Main classification: F16K7
IPC codes: F01M13, F16K7