GB2339885A

GB2339885A - Temperature and pressure sensitive fluid flow control

Info

Publication number: GB2339885A
Application number: GB9916596A
Authority: GB
Inventors: Harold Victor Bradley
Original assignee: RELIANCE WATER CONTROLS LIMITE
Current assignee: RELIANCE WATER CONTROLS LIMITE
Priority date: 1998-07-18
Filing date: 1999-07-16
Publication date: 2000-02-09
Anticipated expiration: 2019-07-16
Also published as: GB9815557D0; GB9916596D0; GB2339885B

Description

2339885 FLUID FLOW CONTROL DEVICE The present invention relates to a fluid

flow control device for controlling the flow of fluid therethrough according to the temperature and the pressure of the fluid, and particularly, but not exclusively, to a fluid flow control device for controlling the flow of water, and to fluid heating systems comprising one or more fluid flow control devices.

Many electrical units, such as fluid heating systems, use fluid flow control devices, for example instantaneous showers and handwash units, instantaneous electric water heaters and boilers. The temperature of the outlet water flow from systems such as these can be hazardous and in many applications are subject to strict governmental controls where the temperature of the outlet flow must not exceed a maximum specified value.

These systems often use constant rate heat exchangers. In the winter the temperature of the inlet water flow is usually around PC, but in the summer this can increase to approximately 20'C. This means that to achieve the same outlet flow temperature throughout the year a low inlet flow is required in the winter and a high inlet flow is required in the summer.

When the inlet flow is controlled by a fluid flow control device, these often require manual adjustment to achieve an outlet flow temperature which does not exceed the maximum specified value.

The pressure of the inlet water flow can also affect the temperature of the 25. outlet water flow, and, when a constant rate heat exchanger is used in the heating system, a high inlet flow due to high inlet fluid pressure will result in a low outlet temperature and a low inlet flow due to low inlet fluid pressure will result in a high outlet temperature.

2 It is therefore desirable to provide a fluid flow control device which automatically controls the flow of fluid therethrough according to the temperature and the pressure of the inlet flow.

According to a first aspect of the present invention there is provided a fluid flow control device comprising an inlet passageway for the fluid, an outlet passageway for the fluid and a fluid flow path connecting the inlet passageway to the outlet passageway, in which the fluid flow path includes one or more temperature sensitive control means to control the flow of the fluid through the fluid flow path according to the temperature of the fluid, and one or more pressure sensitive control means to control the flow of the fluid through the fluid flow path according to the pressure of the fluid.

The or each or some of the temperature sensitive control means may control the flow of the fluid such that the higher the temperature of the fluid the higher the fluid flow. Alternatively, the or each or some of the temperature sensitive control means may control the flow of the fluid such that the higher the temperature of the fluid the lower the fluid flow. When more than one temperature sensitive control means are provided, some of these may control the flow of the fluid such that the higher the temperature of the fluid the higher the fluid flow, and some of these may control the flow of the fluid such that the higher the temperature of the fluid the lower the fluid flow.

The or each or some of the pressure sensitive control means may regulate the flow of the fluid when subject to variations in the pressure of the fluid. Preferably, the or each or some of the pressure sensitive control means regulate the flow of fluid through the device, such that the flow of the fluid from the outlet passageway of the device is not sensitive to variations in the pressure of the flow of the fluid into the inlet passageway of the device, i.e.

3 the outlet fluid flow does not vary substantially when the pressure of the inlet fluid flow varies.

The or each or some of the temperature sensitive control means and the or each or some of the pressure sensitive control means may be situated at the same location of the fluid flow path, or at different locations of the fluid flow path. In a preferred embodiment, the or each temperature sensitive control means is situated at the same location of the fluid flow path as a pressure sensitive control means.

The or each or some of the temperature sensitive control means may comprise one or more fluid flow regulators. The or each fluid flow regulator may be frusto conical in shape, and may be provided with one or more flutes on an outer surface thereof. The or each fluid flow regulator may be linked to one or more temperature sensitive members. In a first embodiment, a single fluid flow regulator is linked to a single temperature sensitive member. In a second embodiment, a single fluid flow regulator is linked to two temperature sensitive members. In a third embodiment, two fluid flow regulators are each linked to the same temperature sensitive member. The or each temperature sensitive member may comprise a temperature sensitive material, such as a wax. A piston may be provided between the or each temperature sensitive member and the or each fluid flow regulator.

The or each or some of the fluid flow regulators may regulate the flow of the fluid in response to changes in volume of the or each temperature sensitive member to which they are linked, the changes being caused by temperature variations of the fluid. A change of volume of the or each temperature sensitive member may cause movement of one or more pistons to which each temperature sensitive member is linked, which in turn causes 4 movement of one or more fluid flow regulators to which each piston is linked, regulating the flow of the fluid. Retaining means may be provided which act on the or each fluid flow regulator causing movement thereof in a direction opposite to the movement caused by the or each piston. The 5 retaining means may comprise a spring.

The or each fluid flow regulator may be located in a housing, and a portion of the fluid flow path may be defined between the fluid flow regulator and its housing. The housing of the or each fluid flow regulator may be annular in shape, and the or each fluid flow regulator may be located co-axially within its housing. The or each housing may be made of a plastics material, or of a metallic material. The position of the or each fluid flow regulator in its housing preferably regulates the flow of fluid through the portion of the fluid flow path. The position of the or each fluid flow regulator in its housing may be controlled by changes in the volume of the or each temperature sensitive member to which the fluid flow regulator is linked. Preferably the positioning of the or each fluid flow regulator in its housing is such that an increased fluid temperature, causing an increase in volume of the or each temperature sensitive member to which the fluid flow regulator is linked, will cause an increased flow of fluid through the portion of the fluid flow path.

The or each or some of the pressure sensitive control means may comprise one or more deformable members, e.g. an o-ring, placed in the fluid flow path. Preferably, when subjected to an increased inlet fluid pressure the or each member deforms to reduce the area of a portion of the fluid flow path, and when subjected to a decreased inlet fluid pressure the or each member relaxes to increase the area of the portion of the fluid flow path, so regulating the fluid flow through the device. The or each deformable member may be placed between a fluid flow regulator and a housing of a temperature sensitive control means. Preferably the or each member is in the form of an o-ring which surrounds the or each fluid flow regulator of the temperature sensitive control means.

When more than one temperature sensitive control means is provided in the fluid flow path, these may act in tandem, or may act sequentially. When more than one pressure sensitive control means is provided in the fluid flow path, these may act in tandem or may act sequentially.

The fluid flow control device may comprise a housing. This may comprise two members. The members may be permanently sealed together, providing a dispensable device. Alternatively, the members may be separably held together, providing a serviceable device. A sealing element may be located between the members, to provide a fluid seal. The members may be made 15 of a plastics material or a metallic material.

The fluid flow control device may be capable of calibration. The fluid may be water.

According to a second aspect of the present invention, there is provided a fluid heating system comprising one or more fluid flow control devices according to the first aspect of the invention.

Embodiments of the invention will now be described by way of example 25 only with reference to the accompanying drawings, in which, Figure 1 is a cross-sectional view of a first embodiment of a fluid flow control device in accordance with the present invention; 6 Figure 2 is a cross-sectional view of a second embodiment of a fluid flow control device; Figure 3 is a cross-sectional view of a third embodiment of a fluid flow control device; Figure 4 is a cross-sectional view of a fourth embodiment of a fluid flow control device, and Figure 5 is a schematic representation of a fluid flow control device used within a fluid heating system.

Referring to Figure 1, the fluid flow control device comprises a housing 10 having a first member 41 and a second member 42, both substantially cylindrical in shape. An annular portion 43 of the first member 41 slots into an end 44 of the second member 42 as shown. The members are separably held together, providing a serviceable device. An o-ring 45 is located between the members to provide a fluid seal. The members are made of a plastics material.

The housing 10 forms an inlet passageway 11, an outlet passageway 12 and a fluid flow path, indicated by arrow 40, connecting the inlet passageway to the outlet passageway. A temperature sensitive control means and a pressure sensitive control means are situated in the flow path. 25 The temperature sensitive control means comprises a fluid flow regulator 13 located in a control means housing 14. The fluid flow regulator is substantially hollow and frusto-conical in shape and has a multi-fluted outer surface. The housing 14 is annular and is held in place in the fluid flow path between a carrier 15 and an annular shoulder 16 of the first member 41 of the housing 10. An o-ring seal 17 is provided between the carrier 15 and 7 the shoulder 16. The control means housing is made of a plastics material. The control means housing 14 could be integral with the housing 10.

The temperature sensitive control means further comprises a temperature sensitive member in the form of a wax element 18, held within the fluid flow path of the control device by the carrier 15. The wax element abuts a first end 19 of a piston 20. A second end 21 of the piston is received within a recess 22 of a solid, cylindrical register 23 such that the second end 21 of the piston 20 abuts a shoulder 24 of the register. The register is located co- axially within the fluid flow regulator 13, such that an annular lip 25 of the register abuts the tip 26 of the register. A spring 27 is located between a second end 28 of the regulator and a shoulder 29 formed on the housing 10. A locknut 46 surrounds a portion 47 of the wax element 18 and engages against the carrier 15. The locknut is adjustable and allows calibration of the control device.

The pressure sensitive control means comprises a deformable o-ring 30 made from a rubber or synthetic material. The o-ring is located within an annular groove 31 formed within the control means housing 14. The o-ring surrounds and is co-axial with the fluid flow regulator 13.

In use, the fluid flow control means is connected via the inlet and outlet passageways to pipework or other such conduits of, for example, a fluid heating system carrying the fluid to and from the device. When the temperature of the inlet fluid is relatively low (for example at approximately 5'C in the winter), the wax element 18 is contracted and the piston 19 retracted as shown in the upper part of Figure 1. The spring 27 acts on the fluid flow regulator 13 and therethrough on the register 23 to push it against the retracted piston. The fluid flow regulator is thus positioned with its thicker, base end 28 located within the control means 8 housing 14. The area of the flow path defined between the housing and the regulator is relatively reduced and the flow of the fluid through the device therefore reduced.

If the temperature of the inlet fluid increases, for example to approximately 20'C in the summer, the wax element will expand forcing the piston 19 outwards away from the element. This in turn, forces the register 13 and the regulator 23 towards the inlet end of the device against the force of the spring 27. This positions the tip 26 of the regulator within the control means housing, and the flow area between the housing and the regulator is increased thereby increasing the flow of fluid through the device. Thus the device achieves relatively low fluid flow in the winter and relatively high fluid flow in the summer. When the control device is attached to a constant rate heat exchanger, the output temperature of the fluid from the exchanger is thus stabilised.

In addition to controlling the flow of fluid according to the temperature of the fluid, the control device also controls the flow according to the pressure of the fluid. If the pressure is relatively high the o-ring 30 deforms in the flow stream and reduces the area of the flow path between the control means housing 14 and the regulator 13 by partially blocking the multifluted, frusto-conical regulator. When the pressure of the inlet fluid flow decreases the o-ring relaxes away from the regulator unblocking the flutes and increasing the area of the flow path. Hence the flow of fluid through the device is regulated according to the pressure of the inlet fluid, and the outlet fluid flow is not substantially changed even when the pressure of the inlet fluid flow changes. When the device is attached to a constant rate heat exchanger, the outlet temperature of the exchanger will be relatively stable regardless of the pressure of the fluid inlet in to the control device.

9 Figure 2 shows a second embodiment of the fluid flow control device. This comprises a housing 90 which forms an inlet passageway 91, an outlet passageway 92 and a fluid flow path connecting the passageways. A takeoff port I 10 is also provided. Temperature sensitive control means and 5 pressure sensitive control means are situated in the flow path.

The temperature sensitive control means comprises a fluid flow regulator 93 located in an annular portion 94 of the housing 90. The regulator is substantially hollow and frusto-conical in shape, and has a multi-fluted outer surface 95 and a multi-fluted inner surface 96.

The temperature sensitive control means further comprises a first temperature sensitive member in the form of a first wax element 97. This is held within the housing 90 by a multi-spoked retainer 198. The first wax element abuts a first end 98 of a piston 99. A second end 100 of the piston abuts a second temperature sensitive member in the form of a second wax element 101. A shank 102 of this element is attached to the inner surface of the regulator 93. A spring 103 is located between a shoulder 104 of the second wax element 10 1, and a shoulder 105 formed on the housing 90. 20 The pressure sensitive control means comprises a deformable o-ring 106 made from a rubber or synthetic material. The o-ring is located within an annular groove 107 formed within the portion 94 of the housing 90. The o- ring surrounds and is co-axial with the fluid flow regulator.

In use, this fluid flow control means is connected via the inlet and outlet passageways to pipework or other such conduits carrying a fluid to and from the device. The take-off port 110 is also connected to a conduit, and may Supply iDlet fluid directly to a part of a heating system, e.g. a fluid mixing valve of such a system.

If the temperature of the inlet fluid is relatively low (for example at approximately PC in the winter), the first wax element 97 and the second wax element 101 are contracted and the common piston 99 is retracted as shown in the upper part of Figure 2. The spring 103 acts on the second wax element 101 to push it against the retracted piston. As the fluid flow regulator 93 is attached to the second wax element, it is thus positioned with its thicker, base end located within the annular portion 94 of the housing 90. The area of the flow path defined between the housing and the regulator is relatively reduced and the flow of the fluid through the device therefore reduced.

If the temperature of the inlet fluid is increased (for example to approximately 20'C in the summer), the first wax element 97 and the second wax element 101 will expand forcing the common piston 99 outward away from both elements. As the first wax element 97 is constrained by the multi-spoked register 198, the second wax element 101 and the regulator 93 are forced towards the inlet end of the device against the force of the spring 103. This positions the tip of the regulator within the annular portion 94, and the flow area between the housing and the regulator is increased thereby increasing the flow of fluid through the device. Thus, this control device achieves relatively high fluid flow in the summer.

This control device also controls the flow of fluid therethrough according to the pressure of the inlet fluid. If the pressure of this fluid is relatively high, the o-ring 106 deforms in the flow stream and reduces the area of the flow path between the annular portion 94 of the housing and the regulator 93 by partially blocking the multi-flutes provided on the outer surface of the regulator. When the pressure of the inlet fluid flow decreases the o- ring 106 relaxes away from the regulator un-blocking the flutes and increasing the area of the flow path. Hence the flow of fluid through this device is regulated according to the pressure of the inlet fluid, and the outlet fluid flow does not vary substantially even when the pressure of the inlet fluid changes.

Figures 3 and 4 show further embodiments of the fluid flow control device, in which a temperature sensitive control means and a pressure sensitive control means are employed. In Figure 3 the fluid flow regulators of the temperature sensitive control means are positioned end to end in the fluid flow path. Expansion of a wax element 60 drives a piston 61 which causes movement, via a register 62, of a first regulator 63 and a second regulator 64 in their respective housings. A return spring 65 acts on the second regulator and through this on the register and the first regulator. In use, the control device of this embodiment operates as before, allowing a high fluid flow through the device when the temperature of the fluid is high, and a low fluid flow when the temperature of the fluid is low. At the same time, if the pressure of the inlet fluid flow is high, the pressure sensitive control means act as before to reduce the flow through the device, and when the pressure of the inlet fluid flow is low, the pressure sensitive control means act to increase the flow through the device.

In Figure 4 the temperature sensitive control means and the pressure sensitive control means are placed side by side in the fluid flow path and operate in tandem. Expansion of a wax element 70 drives a piston 71 which in turn drives a register 72 which moves fluid flow regulators 73,74 in their respective housings. Again, a high temperature inlet fluid will cause high fluid flow through the device, and the pressure sensitive control means operate as before to regulate the flow of fluid through the device.

12 Figure 5 shows a schematic representation of a fluid heating system. This comprises a fluid flow control device 80 connected to a constant rate heat exchanger 81 and a fluid mixing valve 82. Fluid enters the device 80 where its flow is controlled as before. Outlet fluid from the device then enters the heat exchanger where it is heated and passed to fluid mixing valve 82. The amount of heat transferred to the fluid by the heat exchanger will depend on the flow of the fluid through the exchanger. If this is high then less heat is transferred than when the flow is low. If the temperature of the inlet fluid to the exchanger is high then it is desirable to transfer less heat to this fluid, in order that the maximum specified temperature is not exceeded, i.e. it is desirable that the flow of this fluid is high. When the temperature of the inlet fluid to the exchanger is low, it is desirable to transfer more heat to this fluid, i.e. it is desirable that the flow of this fluid is low. This is achieved by the fluid flow control device. Outlet fluid from the exchanger is passed to a fluid mixing valve, and from there to an outlet of the heating system. To further stabilise the outlet fluid temperature from the heating system, a non-return valve 83 is provided between the inlet of the control device and the fluid mixing valve 82. This latter valve blends the inlet fluid with fluid from the exchanger to give an outlet fluid whose temperature is further stabilised. The fluid mixing valve 82 may be adjustable to provide selectable, stabilised lower outlet fluid temperatures.

Claims

13 CLAIMS

I A fluid flow control device comprising an inlet passageway for the fluid, an outlet passageway for the fluid and a fluid flow path connecting the inlet passageway to the outlet passageway, in which the fluid flow path includes one or more temperature sensitive control means to control the flow of the fluid through the fluid flow path according to the temperature of the fluid, and one or more pressure sensitive control means to control the flow of the fluid through the fluid flow path according to the pressure of the fluid.

2. A device according to claim I in which the or each or some of the temperature sensitive control means control the flow of tfie-fluid such that the higher the temperature of the fluid the higher the fluid flow.

3. A device according to claim I in which the or each or some of the temperature sensitive control means control the flow of the fluid such that the higher the temperature of the fluid the lower the fluid flow.

4. A device according to any preceding claim in which the or each or some of the pressure sensitive control means regulate the flow of the fluid when subject to variations in the pressure of the fluid.

5. A device according to claim 4 in which the or each or some of the pressure sensitive control means regulate the flow of fluid through the device, such that the flow of fluid from the outlet passageway of the device is not sensitive to variations in the pressure of the flow of fluid into the inlet passageway of the device, i.e. the outlet fluid flow does not vary substantially when the pressure of the inlet fluid flow varies.

14

6. A device according to any preceding claim in which the or each or some of the temperature sensitive control means and the or each or some of the pressure sensitive control means are situated at the same location of the fluid flow path.

7. A device according to any of claims I to 5 in which the or each or some of the temperature sensitive control means and the or each or some of the pressure sensitive control means are situated at different locations of the fluid flow path.

8. A device according to any preceding claim in which the or each or some of the temperature sensitive control means comprise one or more fluid flow regulators.

9. A device according to claim 8 in which the or each fluid flow regulator is frusto conical in shape, and is provided with one or more flutes on an outer surface thereof.

10. A device according to claim 8 or claim 9 in which the or each fluid 20 flow regulator is linked to one or more temperature sensitive members.

11. A device according to claim 10 in which a single fluid flow regulator is linked to a single temperature sensitive member.

12. A device according to claim 10 in which a single fluid flow regulator is linked to two temperature sensitive members.

13. A device according to claim 10 in which two fluid flow regulators are each linked to the same temperature sensitive member.

14. A device according to any of claims 10 to 13 in which the or each temperature sensitive member comprises a temperature sensitive material.

15. A device according to claim 14 in which the temperature sensitive 5 material is a wax.

16. A device according to any of claims 10 to 15 in which a piston is provided between the or each temperature sensitive member and the or each fluid flow regulator.

17. A device according to any of claims 10 to 16 in which the or each or some of the fluid flow regulators regulate the flow of the fluid in response to changes in volume of the or each temperature sensitive member to which they are linked, the changes being caused by temperature variations of the fluid.

18. A device according to claim 17 as dependent from claim 16 in which a change of volume of the or each temperature sensitive member causes movement of one or more pistons to which each temperature sensitive member is linked, which in turn cause-s movement of one or more fluid flow regulators to which the or each piston is linked, regulating the flow of the fluid.

19. A device according to 18 in which retaining means is provided which act on the or each fluid flow regulator causing movement thereof in a direction opposite to the movement caused by the or each piston.

20. A device according to claim 19 in which the retaining means comprises a spring.

16

21. A device according to any of claims 8 to 20 in which the or each fluid flow regulator is located in a housing, and a portion of the fluid flow path is defined between the fluid flow regulator and its housing.

22. A device according to claim 21 in which the housing is annular in shape, and the or each fluid flow regulator is located co-axially within its housing.

23. A device according to claim 21 or claim 22 in which the housing is made of a plastics material.

24. A device according to claim 21 or claim 22 in which the housing is made of a metallic material.

25. A device according to any of claims 21 to 24 in which the position of the or each fluid flow regulator in its housing regulates the flow of fluid through the portion of the fluid flow path.

26. A device according to claim 25 as dependent from any of claims 10 to 24 in which the position of the or each fluid flow regulator in its housing is controlled by changes in the volume of the or each temperature sensitive member to which the fluid flow regulator is linked.

27. A device according to claim 26 in which the positioning of the or each fluid flow regulator in its housing is such that an increased fluid temperature, causing an increase in the volume of the or each temperature sensitive member to which the fluid flow regulator is linked, will cause an increased flow of fluid through the portion of the fluid flow path.

17

28. A device according to any preceding claim in which the or each or some of the pressure sensitive control means comprises one or more deformable members placed in the fluid flow path.

29. A device according to claim 28 in which the or each deformable member, when subjected to an increased inlet fluid pressure, deforms to reduce the area of a portion of the fluid flow path, and, when subjected to a decreased inlet fluid pressure, relaxes to increase the area of the portion of the fluid flow path, so regulating the fluid flow through the device.

30. A device according to claim 28 or claim 29 in which the or each deformable member is placed between a fluid flow regulator and a housing of a temperature sensitive control means.

31. A device according to claim 30 in which the or each deformable member is in the form of an o-ring which surrounds the or each fluid flow regulator of the temperature sensitive control means.

32. A device according to any preceding claim in which more than one temperature sensitive control means is provided in the fluid flow path, which act in tandem.

33. A device according to any of claims I to 31 in which more than one temperature sensitive control means is provided in the fluid flow path, which act sequentially.

34. A device according to any preceding claim in which more than one pressure sensitive control means are provided in the fluid flow path, which act in tandem.

18

35. A device according to any of claims I to 33 in which more than one pressure sensitive control means are provided in the fluid flow path, which act sequentially.

36. A device according to any preceding claim which has a housing comprising two members.

37. A device according to claim 36 in which the members are permanently sealed together, providing a dispensable device.

38. A device according to claim 36 in which the members are separably held together, providing a serviceable device.

39. A device according to any of claims 36 to 38 in which a sealing 15 element is located between the members, to provide a fluid seal.

40. A device according to any of claims 36 to 39 in which the members are made of a plastics material.

41. A device according to any of claims 36 to 39 in which the members are made of a metallic material.

42. A device according to any preceding claim which is capable of calibration. 25

43. A device according to any preceding claim in which the fluid is water.

44. A fluid heating system comprising one or more fluid flow control 30 devices according to any of claims I to 43.

19

45. A fluid flow control device substantially as described herein with reference to Figure I of the accompanying drawings.

46. A fluid flow control device substantially as described herein with 5 reference to Figure 2 of the accompanying drawings.

47. A fluid flow control device substantially as described herein with reference to Figure 3 of the accompanying drawings.

48. A fluid flow control device substantially as described herein with reference to Figure 4 of the accompanying drawings.

49. A fluid heating device substantially as described herein with reference to Figure 5 of the accompanying drawings. 15