GB2515352A

GB2515352A - Radial flow non-return fluid valve assembly

Info

Publication number: GB2515352A
Application number: GB1313022.4A
Authority: GB
Inventors: Thomas Tsoi Hei Ma
Original assignee: Brunel University
Current assignee: Brunel University
Priority date: 2013-06-18
Filing date: 2013-07-22
Publication date: 2014-12-24
Also published as: GB201313022D0; GB201310830D0; WO2014203131A1

Abstract

A radial flow non-return valve assembly comprises a housing 12 having a cylindrical wall 13 and a row of circumferentially spaced openings 16 in the wall to permit fluid to flow from an entrance side to an exit side of the wall. A cylindrical spring collar 18 of circular cross section is located on the exit side 14 of the wall. The resilience of the collar 18 acts to urge the collar 18 into contact with the exit side 14 of the wall 13 so as to obstruct the openings 16 when the fluid pressure at the exit side is equal to or greater than the pressure on the entrance side. The collar 18 is deformed when the fluid pressure at the entrance side exceeds the fluid pressure at the exit side to uncover the openings 16 to allow fluid to flow through the openings in the wall. One circumferential end of the collar 18 is anchored to the housing to leave a single span of the collar free to separate from the exit side 14 of the wall 13, the length of which span extends over at least 60% of the circumferential length of the exit side of the wall.

Description

RADIAL FLOW NON-RETURN FLUID VALVE ASSEMBLY

Field of the invention

The present invention relates to a radial flow non-return fluid valve assembly.

Background of the invention

There are two types of non-return fluid valve assemblies in common use, namely reed valves, where a reed is bent by the fluid pressure to peel it off a valve seat, and a disk valve where a disk retains its shape but is lifted off a valve seat against the action of a spring. Reed valves offer the advantage of high flow capacity but have poor durability because the flexing of the reed causes metal fatigue. Disk valves on the other hand have high durability but have low flow capacity and are only suited to axial flow.

US 3,882,891, which is believed to represent the closest prior art to the present invention, discloses a radial flow non-return fluid valve assembly, comprising a housing having a cylindrical internal wall and a row of circumferentially spaccd openings in thc wall for enabling fluid to be admitted into the interior of the housing, and a cylindrical collar of circular cross section located within the housing. The resilience of the collar acts in a direction to increase the diameter of the collar into contact with the internal wall of the housing so as to obstruct the openings when the internal fluid pressure within the housing is equal to or greater than the external pressure outside the housing, and the collar is deformcd when thc cxtcmal fluid pressurc cxcccds the intcrnal fluid pressure to uncovcr the openings in order to admit fluid into the interior of the housing.

In the latter patent, the collar is secured in its central region to the housing to defrne two reed valves each approximately equal in length to half of the circumference of the internal wall. The free span of the spring forming each reed valve is bent widely away relative to the circumfercntial openings in response to the external pressure cxcccding the internal pressure and such flexing, as mentioned above, adversely affects the durability of the valve assembly.

Obiect of the invention The present invention seeks to provide a radial flow non-return fluid valve assembly which offers the advantages of both high flow rate and good durability.

Summary of the invention

According to the present invention, there is provided a radial flow non-return fluid valve assembly comprising a housing including a cylindrical wall, and a circumferentially elongated opening, or a row of circumferentially spaced openings, in the wall for enabling fluid to flow from an entrance side to an exit side of the wall, and a cylindrical spring collar of circular cross section located on the exit side of the wall, wherein the resilience of the collar acts in a direction to urge the collar into contact with the exit side of the wall so as to obstruct the opening(s) when the fluid pressure at the exit side is equal to or greater than the pressure at the entrance side, and the collar is deformed when the fluid pressure at the entrance side exceeds the fluid pressure at the exit side to uncover the opening(s) in order to allow fluid to flow through the openings in the wall, characterised in that one circumferential end of the collar is anchored to the housing to leave a single span of the collar free to separate from the exit side of the wall, the length of which span extends over at least 60% of the circumferential length of the exit side of the wall.

It has previously been proposed, for example in US 894,286, to use a collar that is free floating, in the sense that it is not permanently anchored at any point to the housing.

While this minimises sharp changes in curvature of the collar at any point along its circumference, and thus reduces metal fatigue, it requires a cage, or another complex mechanical arrangement, to locate the floating collar both radially and axially relative to the housing when the valve is open. In the present invention, a simple fixing (such as a rivet, a screw fastener, a spot weld or a clamp) suffices to retain the collar in position without adversely affecting its durability.

The exit side of the wall maybe its interior side, whereupon the collar would be biased by its own resilience to expand into contact with the inner side of the wall, or it may be the outer side of the wall, whereupon the collar would be biased by its own resilience to contract into contact with the outer side of the wall.

In some embodiments, the housing may include a plurality of cylindrical walls arranged within one another with the exit side being the radially outer side of at least one of the walls and the radially inner side of at least another one of the walls.

In some embodiments of the invention, the collar may have an axial length sufficient to enable it to overlie more than one row of openings, thereby allowing an increased flow rate.

Brief description of the drawins

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an axial section through a radial flow non-return fluid valve assembly of the invention taken along the section line I-I in Figure 2, Figure 2 and 3 are sections taken in the plane 11-IT in Figure 1 with the valve assembly closed and thc valvc asscmbly opcn, rcspcctivcly, Figure 4 is a section similar to that of Figure 1 showing a second embodiment of the invention, Figure 5 is an axial section through an embodiment of the invention in which the non-return valve assembly serves to allow fluid to exit from but not enter into the interior of the valve housing, Figure 6 is a section taken along the line VI-VI in Figure 7 through a non-return valve assembly that may be used to replace a disk valve in a conventional air compressor, and Figure 7 is a view from below of the non-return valve assembly shown in Figure 6.

Detailed description of the embodiment(s)

The radial flow non-return fluid valve assembly 10 shown in Figures 1 to 3 comprises a housing 12 having a wall 13 with a cylindrical inner side 14 and two rows of circumfcrcntially spaced openings 16. A spring collar 18 is located within the housing 12, having the form of a circular cylinder with an axially extending slit 20. A fastener 26 located at or adiacent one circumferential end of the collar 18 serves to anchor the collar 18 to the housing 12. The fastener 26 leaves a span of the collar 18 free to separate from the housing 12, the length of which span extends over at least 60%, more preferably over more than 75%, and more preferably still over more than 85% of the circumferential length of thc inner sidc 14 of the wall 13.

On account of the resilience of the spring collar 18, in its relaxed state shown in Figures 1 and 2 it contacts the inner side 14 of the wall 13 and blocks off the openings 16, thereby preventing fluid flow into the interior of the housing 12 through the openings 16.

However, when the pressure within the housing 12 is lower than the external pressure, the collar 18 is deformed by the differential pressure into the position shown in Figure 3, thereby uncovering the openings 16 and allowing fluid to flow into the interior of the housing 12.

While the fastener 26 serves to locate the collar 18 both circumferentially and axially relative to the housing 12, the fluid forces acting on the collar 18 are substantially uniformly distributed around the circumference of the collar 18, which therefore merely changes in radius without deviating significantly from its essentially circular shape. In other words, there is no sharp change in radius of curvature near the fastened point, nor indeed at any other point along the circumference of the collar 18. In the prior-art known valves, the free span of the spring used to close the valve openings extends, at the most, over only half the circumferential length of the cylindrical wall and the differential forces acting on the spring when the valve is open therefore create a bending moment transmitted to the fastened point tending to reduce the radius of curvature of the spring near that point.

By contrast, in the present invention, the distribution of the differential forces about the circumference of the longer free span of the collar 18 ensures that the bending moment created by the parts of the collar more than 1800 away from the fastened point acts to oppose and reduce the bending moment created by the first half of the collar nearer the fastened point. If the frill length of the free span of the collar approximates to thc entire circumferential length of the exit side of the housing, then the bending moments transmitted to the fastened point created by the remote half and the nearer half of the span will effectively cancel each other out resulting in little or no bending of the spring near that point. By avoiding sharp changes in the radius of curvature of the spring near the fastened point, the effects of metal fatigue, which affect the reliability of the valve assembly, are reduced.

Instead of using a fastener 26, one end of the collar 18 may be anchored to the housing by means of a second split resilient collar that does not overlie openings in the wall of the housing. Such an embodiment in shown in Figure 4, where the collar is formed of two split rings 18a and 18b connected to one another at only one end by means of a bridge piece 18c. In this case, the ring iSa acts in the same manner as the collar 18 in Figures ito 3 while the other ring lSb and the bridge piece 18c act in place of the fastener 26 as a means of anchoring one circumferential end of the ring iSa to the wall 13.

Figure 5 shows an embodiment in which the collar 118 lies outside the wall 13 instead of being inside it, as was the case in the previously described embodiments. In this case, the valve assembly allows fluid to flow from the interior of the housing 12 to its exterior but the function is otherwise entirely analogous to the previously described embodiments. In particular, when the pressure within the housing 12 is above the exterior pressure, the collar 11. expands away from the exit side 114 of thc wall 13 to allow fluid to escape from the openings 16 and under other conditions it contracts under the action of its own resilience into contact with the exit side 114 so as to seal the openings 16. The collar 118 is retained by means of a fastener 26 located near one circumferential end of the collar 118, and is approximately equal in length to the circumference of the exit wall 114 of the housing 12 according to the present invention for the reasons described previously.

The non-return valve assembly 110 of Figures 6 and? is intended as a replacement for a conventional compressor disk valve and combines non-return valves with intemal collars (designated 18) and extemal collars (designated 118) in a concentric configuration to achieve a high total fluid flow rate. The valve assembly 110 uses a central fixing 50 to secure it in the conventional manner to the intake port of an air compressor.

The present invention combines the advantages of the reed valve and the disk valve, that is to say high flow rate and good durability, while not suffering from the disadvantages of either.

Unlike a conventional reed valve, where the reed is subjected to high bending stress near the fixed end and sharp slapping action near the free end causing fatigue failures, the uniform deformation of the cylindrical spring collar of the present invention creates only small bending of the spring collar hence offers much better durability.

In thc present invention, as fluid is being drawn into the housing, the wall of the cylindrical spring collar lifts away from the fluid flow openings in the housing while remaining substantially parallel to the openings in a mariner very different from the wide bending angle of the reed in a reed valve but very similar to the axial lifting movement of the disk in a disk valve.. Whereas the disk valve operates in an axial flow direction and is not suitable for radial flow applications, the valves of the present invention are suitable for radial flow applications and whilc thcy only need have one row of circumferential openings as shown in some of the illustrated embodiments, the ability of a collar to interact with more than one row of openings enables significantly higher flow capacity than can be achieved in a disk valve.

The radial flow non-return fluid valves of the present invention are suitable for use in air compressors, 2-stroke engines, air connectors as described in W0201 2/059865, and various other applications where reed valves and/or disk valves are employed.

Claims

CLAIMS1. A radial flow non-return fluid valve assembly (10) comprising a housing (12) including a cylindrical wall (13), and a circumferentially elongated opening (16), or a row of circumferentially spaced openings (16), in the wall (13) for enabling fluid to flow from an entrance side to an exit side of the wall (13), and a cylindrical spring collar (18) of circular cross section located on thc exit side (14) of the wall (13), wherein the resilience of thc collar (18) acts in a dircction to urge thc collar (18) into contact with thc cxit side (14) of the wall (13) so as to obstruct the opening(s) (16) when the fluid pressure at the exit side is equal to or greater than the pressure on the entrance side, and the collar (18) is deformed when the fluid pressure at the entrance side exceeds the fluid pressure at the exit side to uncover the opening(s) (16) in order to allow fluid to flow through the openings in the wall (13), characterised in that one circumferential end of the collar (18) is anchored to the housing to leave a single span of the collar (18) free to separate from the exit side (14) of the wall (13), the length of which span extends over at least 60% of the circumferential length of the exit side (14) of the wall (13).
2. A radial flow non-return valve as claimcd in claim 1, wherein the exit side of the wall is the inner side and the collar is biased by its own resilience to expand into contact with the inner side of the wall,
3. A radial flow non-return valve as claimed in claim 1, wherein the exit side of the wall is the outer side and the collar is biased by its own resilience to contract into contact with the outer side of the wall.
4. A radial flow non-return valve as claimed in claim 1, wherein the housing includes a plurality of cylindrical walls arranged within one another with the exit side being the radially inner side of at least one of the walls and the radially outer side of at least another one of the walls.
5. A radial flow non-return valve as claimed in any one of the preceding claims, wherein the collar has an axial length sufficient to enable it to overlie more than one row of openings, thereby allowing an increased flow rate.