GB1601375A

GB1601375A - Fluid flow rate control device

Info

Publication number: GB1601375A
Application number: GB2381378A
Authority: GB
Original assignee: Mannesmann R C
Current assignee: Mannesmann R C
Priority date: 1970-12-10
Filing date: 1978-05-30
Publication date: 1981-10-28

Description

(54) A FLUID FLOW RATE CONTROL DEVICE (71) We, REINHARD CARL MANNES MANN, of 563 Remscheid, Burgerstrasse 84, Federal Republic of Germany and WOLF DIETER KEPPEL of 563 Remscheid, Birkenstrasse 25, Federal Republic of Germany, both citizens of the Federal Republic of Germany, trading as MANNESMANN & KEPPEL ELEC TRONICS, of 24 Lempstrasse, 563 Remscheid, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement::- This invention relates to a fluid flow rate control device and constitutes improvements in or modifications of the invention (hereafter referred to as the parent invention) that is the subject of patent No. 1,350,846 (hereinafter referred to as the parent patent) granted to the present applicants.

The parent invention consists in a fluid flow rate control device comprising an elastically deformable ring supported between a housing portion and a core portion situated within the housing portion, one of the portions providing a seating surface contacting the ring, the other one of the portions having a profiled surface provided with recesses, which together with the ring define passages for fluid, the profiled surface and the seating surface including therebetween an angle other than zero and the arrangement being such that admission of fluid under pressure to inlet means communicating with the passages causes the ring to deform elastically and urges the ring into the recesses to reduce the fluid flow cross-section of the passages by an amount, which increases with increasing pressure of the fluid.

From one aspect the present invention consists in a fluid flow rate control device according to Claim 1 of patent No. 1 350 846 in which there is a sealing device movable between an open position in which it permits fluid flow, and a closed position in which it engages the ring and causes the ring to act as a seal preventing fluid flowing through the passages.

From another aspect the present invention consists in a fluid flow rate control device according to Claim 1 of patent No. 1 350 846 in which the profiled surface is on the core portion, and relative axial movement can be effected between the ring and the core portion, whereby in different axial settings of the ring and core portion, within a range of such settings, different parts of the profiled surface co-operate with the ring, those different parts being of different shapes so that in use when the ring and the core portion are at one axial setting in the range the rate of flow of fluid through the passages has a certain value which remains approximately constant and independent of any variation in the differential fluid pressure across the device within a certain range of such pressures, and when the ring and core portion are at another axial setting in the range the rate of flow of fluid through the passages has a certain different value which also remains approximately constant and independent of any variations in the differential fluid pressure across the device within a certain range of such pressures, and in which such relative axial movement can be effected to a closed position in which sealing means is effective to prevent fluid flowing through the passages.

While it would be possible to cause the ring to move axially, it is normally more convenient for axial movement to be carried out only by the core portion and the sealing means.

Embodiments of the present invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a fluid flow rate control device shown in an open position, Figure 2 is a section differeing from Figure 1 only in that it shows the control device in its closed position, Figures 3 and 4 are sections largely similar to Figures 1 and 2 respectively, but illustrating a modified construction and omitting the operating handle, and Figure 5 is a section through another fluid flow rate control device, shown in its closed position.

The control device shown in Figures 1 and 2 comprises a hollow body 10 which may conveniently be formed as a metal casting.

The body illustrated is of unitary construction, but if desired it may be made from two or more components secured together. In use the control device serves to control the flow of fluid, such as water, flowing through the body in the direction of the arrow 11. The body has an inlet and an outlet, but they are not illustrated and may be of convention form; they may for example be provided with outwardly directed flanges or with external screw-threads enabling them to be readily attached to inlet and outlet pipes respectively. The body is formed with an annular shoulder 12 facing the inlet.

A housing 13 is mounted in the body 10; it has circular symmetry and is of step-like radial cross-section. Externally the housing has two cylindrical faces, one of larger diameter than the other. These faces engage complementary internal faces inside the body on each side of the shoulder 12. An annular gap remains between the housing and the shoulder, and contains an O-ring 14 which serves in use to prevent any leakage of fluid between the body and the housing. The housing may be secured in place in any convenient manner; for example there may be a tubular retainer (not shown) which fits inside the body, and of which one end abuts the end of the housing facing the inlet; the other end of the retainer can be located at the inlet. In another alternative that is not shown the housing forms an integral part of the body and the O-ring 14 is consequently omitted.

Internally the housing 13 also has two cylindrical surfaces, one of larger diameter than the other. At the narrower end of the housing is an inwardly directed annular portion 16. The flat inner face of the portion 15 constitutes a seating surface for an elastically deformable ring 16 which is disposed in the narrower portion of the housing. The elastic ring 16 is prevented from escaping axially by a retaining ring 17 which fits into the broader portion of the housing. The retaining ring may be secured in place in any desired manner, but it is preferably removable to enable the elastic ring 16 to be removed and replaced when it becomes worn. Where a tubu lar retainer is provided, as described above, to retain the housing 13 in place, the retainer may be made of sufficient wall-thickness to abut the retaining ring 17 as well and thus to secure it in place.

A sleeve 18, moulded from a suitable plastics material, is mounted in the body so as to project axially through the housing 13.

The sleeve is carried by a spindle 19 which projects axially through it. One end of the sleeve abuts a radial enlargement 20 on the spindle, while the other end of the sleeve abuts a circlip 21 snapped into a circumferential groove in the spindle. A counterbore in the sleeve adjacent to the circlip houses an O-ring 22 which in use prevents liquid leaking between the spindle and the sleeve. Although the sleeve is prevented from axial movement relative to the spindle it is free to rotate on the spindle.

The spindle 19 constitutes an axial extension of a rod 23 which is externally screwthreaded for part of its length adjacent to the enlargement 20 and which carries an operating handle 24 at its free end. The rod 23 extends through a tubular bearing 25 constituting an integral part of the body 10 and co-axial with the housing 13. The bearing is internally screw-threaded for engagement by the externally screw-threaded part of the rod.

A counter-bore at the outer end of the bearing 25 houses an O-ring 26 which in use prevents fluid leaking through the bearing. The O-ring 26 is secured in place by retaining ring 27.

Returning now to the sleeve 18, that portion of the sleeve nearer the enlargement 20 is formed externally with a plurality of axially extending ribs alternating with recesses. The outline of the cross-section of this portion of the sleeve, which will hereinafter be referred to as the core portion, may resemble the outline of the cross-section of a core portion illustrated in the complete specification of the parent patent; it may for example resemble the outline of the core portion 51 shown in Figure 2 of those drawings, or the outline of the core portion 251 shown in Figure 9 of those drawings. However, the core portion of the sleeve 18 is tapered, or at least the recesses in it are tapered so as to become progressively deeper as they approach the enlargement 20.

Therefore the outline of the cross-section of the core portion varies progressively along the sleeve.

Beyond the core portion the sleeve 18 is so shaped as to provide a sealing device which is in the shape of a circumferential rib or bead 28. The main part of the rib 28 has a cylindrical outer surface of diameter slightly smaller than that of the hole in the retaining ring 17, but slightly greater than the diameter of the hole in the elastic ring 16 when that ring is in its relaxed state. That end of the rib 28 nearer the core portion 18 is so shaped as to present a convex, curved surface.

When the device is in use, and is in the open position shown in Figure 1, fluid such as water flows through the body 10 in the direction of the arrow 11. The elastic ring 16 co-operates with the seating surface of the annular portion 15 of the housing 13 and with the adjacent part of the core portion of the sleeve 18 in a manner similar to that described in detail in the complete specification of the parent patent. In consequence the rate of flow of fluid through the device remains approximately constant, even if the pressure differential between the inlet and the outlet rises.If the value of the pressure differential falls outside a certain range of values the rate of flow of fluid will of course no longer remain approximately constant; but it is intended that in normal use of the device the pressure differentials likely to be encountered should be of values falling within that range.

If the operating handle 24 is rotated in either direction the sleeve 18 is displaced axially and a different part of the core portion then co-operates with the elastic ring 16. As the cross-section of the core portion varies along the length of the core portion as described above, the consequence of the displacement is that the elastic ring again cooperates with the core portion to regulate the fluid flow so that the rate or fluid flow is approximately constant, but the actual rate or fluid flow is different from what it was before the displacement was effected. Again the new flow rate remains approximately constant within a range of pressure differentials.

This new range of pressure differentials may be the same as the other such range or may differ somewhat from it. From the foregoing description it will be appreciated that the sleeve may be adjusted to any desired position within a range of positions, and that each position of the sleeve leads to a corresponding, characteristic rate of fluid flow which is independent of the pressure differential between the inlet and the outlet.

If the operating handle is rotated to cause the rib 28 to approach the elastic ring 16 there comes a setting where the part of the sleeve adjacent to the ring is not profiled, but is merely cylindrical. At, and beyond, this setting the device no longer operates in the manner described to provide a constant rate of fluid flow. Further rotation of the handle causes the rib 28 to approach the retaining ring 17 so closely that the flow rate is determined largely by the size of the gap between the rib and the retaining ring. For this reason it is desirable to ensure there is sufficient axial spacing between the rib 28 and the profiled core portion of the sleeve to ensure that the restriction imposed by the rib as it approaches the retaining ring does not become significant before the core portion has passed beyond the elastic ring.

As rotation continues the curved, convex end of the rib enters the elastic ring 16 and seals against it, also urging the ring outwards into sealing or more tight sealing engagement with the adjacent cylindrical wall of the housing 13, and into sealing engagement with the seating surface. Finally a flat end surface on radial enlargement 20 comes into contact with a flat end surface on the bearing 25, as shown in Figure 2, and prevents any further axial movement of the sleeve. The radial enlargement and bearing thus afford positive stop means to prevent the rib 28 moving beyond its closed position. Fluid can no longer flow through the device, and leakage is prevented by the O-rings 14 and 23.

During the final part of its movement to the closed position, after its initial engagement with the ring, the sleeve no longer rotates with the spindle.

Due to manufacturing tolerances the relative axial positions of the rib 28 and the elastic ring 16 when the device is in its closed position may vary from device to device. The shape of the rib, however, is such that there is a relatively wide range of relative axial positions in which the rib is effective to cause the ring to act as a seal, so that no special steps need to be taken to provide for individual adjustment of the devices after assembly.

A modified construction of device is illustrated in Figures 3 and 4 where parts similar to those in the embodiment illustrated in Figures 1 and 2 are given the same reference numerals.

The principal modification is in the substitution of an annular sealing flange 30 for the rib 28. As it approaches its closed position this flange operates to engage one end of the ring so that in the closed position, shown in Figure 4 the ring is urged axially against the seating surface of the housing 13. A metal washer 31 is provided between the sleeve and the circlip 21 to support and stiffen the flange 30. In order to enable the flange to reach the elastic ring the retaining ring 17 is omitted, and in use reliance has to be placed on the fluid flow to push it axially into its position of use in the housing if it should have become axially displaced.While this modified construction is quite effective in practice, the range of axial positions of the flange 30 in which sealing is effective is generally less extensive than the range of axial positions of the rib 28 in which sealing is effective. Consequently the tolerances of the components must be narrower than those of the device illustrated in Figures 1 and 2, or individual adjustment of the devices may become necessary after assembly.

It will be appreciated from the foregoing description that the rib 28 or the sealing flange 30, as the case may be, constitutes a sealing device which forms part of sealing means also including the elastic ring 16 and the housing 13.

Figure 5 illustrates a further form of device. The device has a hollow body 32 formed as a metal casting. In use water flows through the device in the direction of the arrow 33; the water leaves through a lateral duct 34. The body is formed internally with a shoulder 35. A seating ring 36 made of nylon is a force fit in the body and abuts the shoul der 35. An elastic ring 37, similar to the elastic ring shown in Figure 1, is disposed in the body adjacent to the seating ring 36. A selflocking washer 38, made of spring steel, is pressed into the outer part of the interior of the body and serves to prevent the escape of the elastic ring 16.

A spindle 39 extends axially inside the housing and constitutes an extension of a rod 40, the spindle and rod being similar to those with reference numerals 20 and 23 respectively and shown in Figure 1. An externally screw threaded part of the rod 40 engages an internally screw-threaded bearing 41 constituting an integral part of the body 32. The rod carries an operating handle (not shown) at its free end. The rod 40 carries a sleeve 42, similar to the sleeve 18, housing an O-ring 43, similar to the O-ring 22. A washer 44, similar to the washer 31, is held in place by a spring retainer 45 which is located in a groove in the spindle 39 and urges the washer and sleeve axially against an enlargement 46 on the rod, similar to the enlargement 20.

The device operates in a manner similar to that described above in connection with the device illustrated in Figures 1 and 2 of the accompanying drawings.

Devices of the kind described with reference to the accompanying drawings may be used for many different purposes. One particular application is in the control of the supply of cold water to an electrically powered water heater of the through-flow type. In a typical water heater of that type the water flows through a series of passageways containing electrically heated elements so connected as to yield a substantially constant power out put. By varying the rate of flow of water through the passageways the user can bring about variation in the temperature of the water issuing from the passageways. To avoid unwanted changes in water tempera ture, however, it is necessary in practice to ensure that the rate of flow of water is inde pendent of changes in the pressure of water supplied to the heater.The provision of a device of the kind described above and illus trated in the accompanying drawings to con trol the water supply to the heater enables the user to adjust the rate of flow of water to cause the water to issue from the heater at any desired temperature, in the knowledge that the temperature will remain substantially constant even though there may be variations in the pressure of the water supply. Further the device enables the water supply to be cut off entirely when the heater is no longer re quired for use, thus obviating the need for a separate water tap for that purpose.

WHAT WE CLAIM IS: 1. A fluid flow rate control device according to Claim 1 of Patent No. 1 350 846 in which there is a sealing device movable between an open position in which it permits fluid flow, and a closed position in which it engages the ring and causes the ring to act as a seal preventing fluid flowing through the passages.

2. A device according to Claim 1 in which there is a positive stop means operative to prevent movement of the sealing device beyond said closed position.

3. A device according to either of Claims 1 and 2 in which the sealing device in its closed position causes the ring to seal against the seating surface.

4. A fluid flow rate control device according to Claim 1 of Patent No. 1 350 846 in which the profiled surface is on the core portion, and relative axial movement can be effected between the ring and the core portion, whereby in different axial settings of the ring and core portion, within a range of such settings, different parts of the profiled surface co-operate with the ring, those different parts being of different shapes so that in use when the ring and the core portion are at one axial setting in the range the rate of flow of fluid through the passages has a certain value which remains approximately constant and independent of any variation in the differential fluid pressure across the device within a certain range of such pressures, and when the ring and core portion are at another axial setting in the range the rate of flow of fluid through the passages has a certain different value which also remains approximately constant and independent of any vairations in the differential fluid pressure across the device within a certain range of such pressures, and in which such relative axial movement can be effected to a closed position in which sealing means is effective to prevent fluid flowing through the passages.

5. A device according to Claim 4 in which the sealing means includes the ring and a sealing device which in the closed position engages the ring and causes the ring to act as a seal preventing fluid flowing through the passages.

6. A device according to Claim 5 in which the sealing device is in fixed axial relationship with the core portion.

7. A device according to either of Claims 5 and 6 in which the closed position is at or beyond one end of said range of settings of the ring and core portion.

8. A device according to Claim 7 in which there is positive stop means operative to prevent the relative movement of the sealing device and the ring beyond the closed position.

9. A device according to any of Claims 6 to 8 in which the sealing device is formed integrally with the core portion.

10. A device according to any of Claims 5 to 9 in which the sealing device is so shaped that as it approaches the closed position it

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. der 35. An elastic ring 37, similar to the elastic ring shown in Figure 1, is disposed in the body adjacent to the seating ring 36. A selflocking washer 38, made of spring steel, is pressed into the outer part of the interior of the body and serves to prevent the escape of the elastic ring 16. A spindle 39 extends axially inside the housing and constitutes an extension of a rod 40, the spindle and rod being similar to those with reference numerals 20 and 23 respectively and shown in Figure 1. An externally screw threaded part of the rod 40 engages an internally screw-threaded bearing 41 constituting an integral part of the body 32. The rod carries an operating handle (not shown) at its free end. The rod 40 carries a sleeve 42, similar to the sleeve 18, housing an O-ring 43, similar to the O-ring 22. A washer 44, similar to the washer 31, is held in place by a spring retainer 45 which is located in a groove in the spindle 39 and urges the washer and sleeve axially against an enlargement 46 on the rod, similar to the enlargement 20. The device operates in a manner similar to that described above in connection with the device illustrated in Figures 1 and 2 of the accompanying drawings. Devices of the kind described with reference to the accompanying drawings may be used for many different purposes. One particular application is in the control of the supply of cold water to an electrically powered water heater of the through-flow type. In a typical water heater of that type the water flows through a series of passageways containing electrically heated elements so connected as to yield a substantially constant power out put. By varying the rate of flow of water through the passageways the user can bring about variation in the temperature of the water issuing from the passageways. To avoid unwanted changes in water tempera ture, however, it is necessary in practice to ensure that the rate of flow of water is inde pendent of changes in the pressure of water supplied to the heater.The provision of a device of the kind described above and illus trated in the accompanying drawings to con trol the water supply to the heater enables the user to adjust the rate of flow of water to cause the water to issue from the heater at any desired temperature, in the knowledge that the temperature will remain substantially constant even though there may be variations in the pressure of the water supply. Further the device enables the water supply to be cut off entirely when the heater is no longer re quired for use, thus obviating the need for a separate water tap for that purpose. WHAT WE CLAIM IS:

1. A fluid flow rate control device according to Claim 1 of Patent No. 1 350 846 in which there is a sealing device movable between an open position in which it permits fluid flow, and a closed position in which it engages the ring and causes the ring to act as a seal preventing fluid flowing through the passages.

enters the ring, and in the closed position it urges the ring outwards.

11. A device according to any of Claims 5 to 9 in which the sealing device is so shaped that as it approaches the closed position it engages one end of the ring, and in the closed position it urges the ring axially against the seating surface.

12. A device according to any of Claims 4 to 11 in which there is complementary screw and nut means capable of relative rotation to cause axial movement of the core relative to the ring.

13. A device according to Claim 12 in which the core is mounted on a rotatable spindle fast with said screw means.

14. A device according to Claim 13 in which the core is free to rotate on the spindle.

15. A device according to any of Claims 4 to 14 in which the shape of the profiled surface on the core portion varies progressively in an axial direction in such a manner that in use the rate of flow of fluid through the passage varies progressively with relative movement of the ring and core portion within said range of settings.

16. A fluid flow rate control device substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

17. A fluid flow rate control device substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.