NZ572607A - Flow regulator for mounting in conduit such as tap outlet with apertured and biased piston slidable relative to housing and blind chamber with balancing of pressure upstream and downstream - Google Patents

Abstract

A flow regulator can be mounted in a conduit, (typically a tap outlet via a threaded coupling sleeve to screw into a tap interior - not shown), and has a piston 8 slidable within a body 4, having an upstream surface 9 and a downstream surface. There is a first fluid passageway defined from the upstream surface 9 to a throttle opening 22 defined between the piston side and a valve seat 16 such that the throttle opening decreases in size as the piston moves downwardly in the direction of fluid flow. A chamber 11 is defined between a lower chamber wall of the body and the downstream surface of the piston 8 such that movement of the piston 8 varies the chamber volume. A spring 14 biases the piston against the direction of flow. A second passageway 13 extends through the piston from the upstream surface 9 to the downstream surface opening into the chamber 11. The chamber 11 is sealed except for the second passageway.

Description

Received by IPONZ 19 July 2011 No: 572607 Date: 5 November 2008 NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION FLOW REGULATING DEVICE We, John William Green, a New Zealand citizen of 36 Wallace Road, Hamilton, New Zealand, and David Stanley Hatt, a New Zealand citizen of Unit 131, 30 Ruakura Road, Hamilton, New Zealand, 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: Received by IPONZ 19 July 2011 FIELD OF THE INVENTION The present invention relates to a flow regulator device. In particular the invention relates to a compact flow regulating device suitable for domestic applications.

BACKGROUND TO THE INVENTION In the field of domestic plumbing there is a growing demand to conserve water. In some countries, legislation has been introduced to limit the allowable flow rate from outlets with this aim. One method of reducing flow from a domestic tap or mixer is to include a fixed restriction. This method is widely used and is commonly achieved by fitting an aeration device to domestic outlets which serve a dual purpose of reducing flow and inducing air into the water stream. Aeration devices give a pleasant soft feel to the water. The flow rate may be perceived by a user as a higher flow rate than is actually flowing. Aeration devices may also reduce noise and splashing.

However, a draw back of flow restrictors in the prior art is that the rate of flow achieved at the outlet may also vary considerably as a function of inlet pressure. This can result in the significant disadvantage of the outlet device delivering too little water at low inlet pressure and too much water when the inlet pressure is high.

Further, it is common for inlet pressure in domestic water delivery pipes to vary from location to location, and the water pressure may also decrease considerably during peak use hours such as early in the morning when much of the population is washing in preparation for their day. During these peak times, the inlet pressure and water flow rate may be considerably reduced. The addition of a flow restrictor can result in further significant reductions in flow rate, and this can lead to unacceptable rates of flow being available for showers etc.

One method of attempting to address this problem is to use a flexible or deformable element which progressively reduces the flow orifice as the inlet pressure increases, thereby maintaining an approximately uniform flow rate over a wider inlet pressure range. In this type of regulator device the deformable element is typically an O-ring, specifically sized and constructed from a material having carefully selected material properties. For this type of device, only relatively small movements and variations of the flow orifice are possible. As a result, the device is only capable of maintaining a uniform flow rate across a relatively small inlet pressure range. For typical domestic installations such devices are fairly insensitive to Received by IPONZ 19 July 2011 pressure differentials below approximately 120 kPa. At pressures below this, the deformable element deforms very little, and the device essentially acts as a fixed restriction.

A flow regulator device that is sensitive to smaller pressure differentials and therefore capable of normalizing flow rate across a wider range of inlet pressures would be useful.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

It is an object of the present invention to provide an improved flow regulating device or to at least provide a useful choice.

SUMMARY OF THE INVENTION In one aspect, the present invention broadly consists in a flow regulator comprising: a body adapted to be mounted in a fluid conduit; a piston moveably mounted within said body and having an up-stream surface and a down-stream surface; a first fluid passageway from said up-stream surface to a throttle opening, said throttle opening restricting said flow through said body and wherein said opening varies in size as said piston moves such that said opening decreases in size as said piston moves in the direction of said flow; a sealed chamber defined by said down-stream surface of said piston and a chamber wall such that said movement of said piston varies the volume of said chamber; a biasing element biasing said piston against the direction of said flow; a second passageway through said piston from said up-stream surface to said downstream surface opening into said chamber.

Preferably in use, the pressure in said chamber is substantially the pressure at said upstream surface.

Received by IPONZ 19 July 2011 Preferably said up-stream surface has a greater area than said down-stream surface Preferably the only opening in said chamber is said second passageway so that said chamber is otherwise sealed.

Preferably the inlet flow to said regulator and the outlet flow from said regulator are substantially parallel with said movement of said piston.

Preferably said inlet flow and said outlet flow are substantially co-axial with said movement of said piston.

Preferably said throttle opening is an annular opening formed between a valve portion or shoulder of said piston and a stationary valve seat.

Preferably the area of the valve seat is substantially the same as the area of said down-stream surface of said piston.

Preferably the opening of said second passageway is substantially in the full path of the fluid flowing through said regulator.

Preferably the diameter of said upstream surface of said piston is substantially as large as the diameter of said body.

Preferably said device includes a plurality of passageways from said up-stream surface to said throttle opening and said plurality of passageways are spaced about the axis of said piston.

Preferably said device including an aerator down-stream of said regulator.

Preferably said aerator includes a fluid inlet, at least one air inlet, a flow screen downstream of said fluid inlet to straighten the flow passing through it, and a baffle plate upstream of said screen to disrupt said flow before it impinges onto said screen.

Received by IPONZ 19 July 2011 Preferably said baffle plate is an annular ring having a flow orifice and a plurality of inward facing protrusions extending into said flow orifice.

In a further aspect, the present invention broadly consists in an aerator assembly comprising: a fluid inlet; at least one air inlet; a flow screen downstream of said fluid inlet to straighten the flow passing through it; and a baffle plate located upstream of said screen to disrupt said flow before it impinges onto said screen.

Preferably said baffle plate is an annular ring having a flow orifice and a plurality of inward facing protrusions extending into said flow orifice.

Preferably said baffle plate is spaced from said screen.

In a further aspect the invention consists in a fixture including a flow regulator as above. In a further aspect the invention consists in an aerator as above.

The term "comprising" as used in this specification and claims means "consisting at least in part of'. When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will be described by way of example only and with reference to the drawings, in which: Received by IPONZ 19 July 2011 - 6 ~ Figure 1 is a perspective cut away view of a flow regulator according to one embodiment of the present invention shown with an aerator.

Figure 2 is a perspective view of the device of Figure 1 shown without an aerator.

Figure 3 is a cut away view of the device of Figure 1 shown installed in a tap fitting and with the piston undisplaced.

Figure 4 is a sectioned view of the flow regulator device of Figure 3 shown with the piston displaced downwards.

Figure 5 is a close-up cut-away view of a flow regulating device according to the present invention shown with the upper filter mesh, outer seal and aerator removed.

Figure 6 is a perspective cut away view of the device shown with an optional baffle included in the aeration assembly.

Figure 7 is a perspective view of the aerator assembly of Figure 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS It will be appreciated that the flow regulator device of the present invention may be used in conjunction with an aerator device as described, or may be used without an aerator. It is most preferred that the flow regulator according to the present invention is compact enough for use in domestic tapware and shower mixers/fixtures and can be fit into the widely used M24 standard threaded hole commonly found in mixer spouts and shower head inlets etc. It will be appreciated that the device can be used in many applications where flow regulation is desired. Further examples could include mixing or non-mixing tapware and direct type water heating systems which may benefit from controlled maximum flow to maintain an acceptable delivery temperature. However it will also be appreciated that other embodiments of the present invention are contemplated in which the components of the flow regulator may be scaled up or down in size to make it suitable for other applications.

Received by IPONZ 19 July 2011 With reference to the Figures, a preferred form of the present invention will now be described in more detail. Flow regulator 1, is preferably adapted to be installed into a fixture such as a typical spout 2, via complementary screw threads (typically M24). Compressible seal 3 is provided to seal between the spout 2 and the body of the regulator device 4. Aerator device 5 is located downstream of the regulator body 4 and in use, draws air through inlets 6 which then becomes entrained in the flow of water. Filter mesh 7 is preferably provided to protect the regulator assembly 1 from debris.

Piston 8 is moveably located within the body 4 of the regulator device. Piston 8, has an upper surface 9 which is exposed to the inlet stream, and a lower surface 10 which defines the upper surface of chamber 11. Piston 8 is moveably mounted with body 4, such that movement of the piston 8 varies the volume of the chamber 11. An O-ring type seal 12 is provided between the chamber wall 11 and the piston 8 to seal the chamber. There is a passageway 13 between the upstream surface 9 and the downstream surface 10 of piston 8, connecting chamber 11 to the upstream inlet pressure. The upper surface 9 of piston 8 is preferably flanged as shown in the figures to present a large surface area to the inlet pressure. The upper surface 9 of piston 8 is provided with flow apertures 15 to allow fluid flow through the device.

A spring 14 is provided to bias moveable piston 8 against the direction of flow through the device (biased upwards as shown in the figures). Down stream of the upper surface 9 of piston 8 is seat 16. A variable throttle opening 17 is formed between the seat 16 and a shoulder portion 18 of piston 8. Downward displacement of the piston 8, results in the restriction opening 17 becoming smaller. Similarly, upwards displacement of the piston 8 (via spring 14) results in the restriction opening 17 becoming larger. Piston 8 also includes hollow 19 to allow fluid flowing through the throttle opening 17 to exit the device without being further impeded.

With particular reference to Figure 2, body 4 includes exits 20 to allow fluid to leave the regulator device. At this point, the device may also include an aerator 5 as previously described to entrain air into the fluid stream.

The operation of a preferred flow regulator device will now be described in more detail with reference to the Figures and in particular Figures 3 & 4. The flow regulator of Figure 3 & 4 is shown attached to a typical spout 2, by means of an aerator 5. When there is no water flowing Received by IPONZ 19 July 2011 through the device, it is in the "rest" position shown in Figure 3. The piston 8 is biased upwards to stop against the upper mesh member 7, by the spring 14. In this position, the shoulder 18 of piston 8 is maximally displaced from the seat 16 and the variable throttle orifice 17 is at its maximum.

When a small flow enters the flow regulator device 1 through the mesh 7, it flows onto the upper surface 9 of piston 8, and through flow apertures 15. From there, the flow goes through the variable throttle opening 17, and flows out of the flow regulating device through exits 20, and through the aerator (if present). The incoming water flow also fills chamber 11 via passage 13. In this case the flow encounters minimal resistance and flows substantially unimpeded through the device.

As flow increases, it exerts a greater pressure on the upper surface 9 of piston 8. As the increasing pressure builds, the downwards force acting on piston 8 also increases until piston 8 begins to be displaced downwards by compressing spring 14. As the increasing flow approaches a predetermined level, the shoulder 18 begins to throttle the opening 17.

As the predetermined set flow rate is reached, the throttling effect creates back pressure in chamber 21 under the piston upper surface. The downward force on the piston from the inlet pressure acting on the upper surface 9, reaches an equilibrium with the upward forces from spring 14, and the forces from the pressures in chambers 11 and 21. This situation is shown in Figure 4, where the piston 8 is displaced downwards and the restriction orifice 17 has closed somewhat.

Any increase in inlet pressure beyond this equilibrium point, which would usually tend to increase flow, is counter-acted by the piston 8 moving downwards slightly closer to the seat 16, thereby further closing the throttle opening 17. This in turn, further increases the back pressure in chamber 21 so that the pressure differential between upper surface 9 and chamber 21 remains substantially the same as before. As a result, the flow is regulated and remains substantially uniform as the inlet pressure increases. The flow remains substantially uniform at inlet pressures above the minimum required to move piston 8 downwards to the begin flow regulation as described above.

Two opposing factors that maintain constant flow are the pressure differential between the upper face 9 of the piston and the chamber 21 vs. the spring force from spring 14. To ensure Received by IPONZ 19 July 2011 that the flow rate is substantially independent of the inlet pressure, passageway 13 transmits the inlet pressure to sealed chamber 11. Whatever change occurs in inlet pressure is therefore transmitted to chamber 21 which helps balance the forces on the piston.

Chamber 21 is preferably the same diameter as orifice 22 in seat 16 so that a balancing force is generated. It is preferable to balance the force so that the device does not shut off the flow when the inlet pressure generates a force greater than the spring force.

After the water passes through seat orifice 22, it flows through channels exits 20 around the outside of body 4 as shown in Figure 5 by arrow 25. As the water discharges from the exits at relatively high velocity, it creates a low pressure zone in the narrow annular space immediately on the inside of the aerator inlet ports 6. These are open to atmosphere via the clearance between the outside diameter of aerator body 5 and the inside diameter of the aerator shell 23. Air is drawn up this clearance, through ports 6 and then mixes with the water in chamber 24. This aerated water then flows through a flow screen grid to ensure that the discharge stream maintains a straight, smooth shape for as long as possible.

A further improvement to the shape of the discharge stream can be achieved by inserting a baffle plate 26 in chamber 24, to create extra turbulence and spread the flow more evenly across the screen. Plate 26 has a generally annular shape with a flow orifice for the flow to flow through. A plurality of inwardly extending protrusions act on the fluid as it flows through the baffle plate 26. It has been found that the "toothed" baffle plate 26 can improve the performance of the aerator.

In order to tailor the regulator of the present invention to achieve differing preset flow rates, spring 14 can be substituted with a spring having a different spring constant. For example, a stronger spring will give more flow through the regulator. Similarly, a weaker spring will result in a lower preset flow rate.

Alternatively, the number and/or size of inlet ports 15 in the piston 8 can be varied. Larger total port area will give more flow, and smaller port area with result in a lower pre-set flow rate.

The flow regulator of the present invention also operates with a very short working stroke which contributes to the compact nature of the device. For example, embodiments of the Received by IPONZ 19 July 2011 invention suited to typical domestic plumbing applications may typically have a stroke as small as approximately 1- 1.5mm. Despite the compact dimensions, the device can function with a small pressure differential thereby enabling the device to work with low inlet pressures. For example the flow regulator can operate with an inlet pressure range between approximately 50 ™ 500 kPa. This performance is aided by the large upper piston surface area (in relation to the throttling element) which maximises the force exerted on the piston by the inlet pressure and improves the sensitivity of the device.

The design of the present invention also allows friction to be minimized allowing the valve to respond quickly and smoothly to inlet pressure changes. The only significant source of friction is the seal 12 on the lower end of the piston as it slides in chamber 11. This feature is particularly important when the flow regulator is small and the actuating force is also small.

A common problem with conventional restriction designs (such as die deformable O ring) is instability during the transition from fully open when die inlet pressure is lower than the minimum working pressure. The preferred device of the present invention has been found to be stable due to there being only minimum restriction immediately down stream of the throttle area.

The device of the present invention is simple enough to lend itself to inexpensive mass production, thereby allowing the unit cost to be low. In particular most of the components can be constructed from plastic, for example acetal copolymer (POM), polyphenylene oxide (PPO) or ABS. Typically die material used should be approved by a relevant authority for the type of application envisaged.

Alternatively, it is anticipated that some applications may benefit from metallic construction, for example from brass or stainless steel etc. In some applications, ceramic components may be particularly suitable.

In addition the device may be configured for snap-fit assembly, which is very quick, and may save space compared to screwed or bolted assembly.

It will be appreciated that the flow regulator device may be used in many different locations. For example, the spout of a basin or the outlet of a shower mixer. In this type of application, the device typically would also incorporate an aerator. Non-aerator versions may be used in in-line applications either within the end use fitting or located up-stream of it.

Received by IPONZ 19 July 2011 The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.

Received by IPONZ 19 July 2011

Claims (15)

1. A flow regulator comprising: a body adapted to be mounted in a fluid conduit; a piston moveably mounted within said body and having an up-stream surface and a down-stream surface; a first fluid passageway from said up-stream surface to a throttle opening, said throttle opening restricting said flow through said body and wherein said opening varies in size as said piston moves such that said opening decreases in size as said piston moves in the direction of said flow; a sealed chamber defined by said down-stream surface of said piston and a chamber wall such that said movement of said piston varies the volume of said chamber; a biasing element biasing said piston against the direction of said flow; a second passageway through said piston from said up-stream surface to said downstream surface opening into said chamber.

2. A flow regulator as claimed in claim 1, wherein in use, the pressure in said chamber is substantially the pressure at said upstream surface.

3. A flow regulator as claimed in claim 1 or claim 2, wherein said up-stream surface has a greater area than said down-stream surface

4. A flow regulator as claimed in any one of claims 1 to 3, wherein the only opening in said chamber is said second passageway so that said chamber is otherwise sealed.

5. A flow regulator as claimed in any one of claims 1 to 4, wherein the inlet flow to said regulator and the outlet flow from said regulator are substantially parallel with said movement of said piston.

6. A flow regulator as claimed in claim 5, wherein said inlet flow and said outlet flow are substantially co-axial with said movement of said piston.

7. A flow regulator as claimed in any one of claims 1 to 6, wherein said throttle opening is an annular opening formed between a valve portion or shoulder of said piston and a stationary valve seat. Received by IPONZ 19 July 2011 - 13-

8. A flow regulator as claimed in any one of claims 1 to 7, wherein the area of the valve seat is substantially the same as the area of said down-stream surface of said piston,

9. A flow regulator as claimed in any one of claims 1 to 8, wherein the opening of said second passageway is substantially in the fall path of the fluid flowing through said regulator.

10. A flow regulator as claimed in any one of claims 1 to 9, wherein the diameter of said upstream surface of said piston is substantially as large as the diameter of said body.

11. A flow regulator as claimed in any one of claims 1 to 10, wherein said device includes a plurality of passageways from said up-stream surface to said throttle opening and said plurality of passageways are spaced about the axis of said piston.

12. A flow regulator as claimed in any one of claims 1 to 11, including an aerator downstream of said regulator.

13. A flow regulator as claimed in claim 12, wherein said aerator includes a fluid inlet, at least one air inlet, a flow screen downstream of said fluid inlet to straighten the flow passing through it, and a baffle plate upstream of said screen to disrupt said flow before it impinges onto said screen.

14. A flow regulator as claimed in claim 13, wherein said baffle plate is an annular ring having a flow orifice and a plurality of inward facing protrusions extending into said flow orifice.

15. A flow regulator substantially as herein described and with reference to Figures 1 to 5. dated this nay 0f Aj Park PER AGENTS FOR l nt APPLICANT"