WO2021123155A2

WO2021123155A2 - An improved pump

Info

Publication number: WO2021123155A2
Application number: PCT/EP2020/087008
Authority: WO
Inventors: J. O'donnell; S. Mckay
Original assignee: Rift Ip Limited
Priority date: 2019-12-19
Filing date: 2020-12-18
Publication date: 2021-06-24
Also published as: GB2604554B; GB202208749D0; WO2021123155A3; GB2604554A; GB2620694A

Abstract

Described is a twin ended pump apparatus comprising: a housing; a first pump at one end of the housing, said first pump comprising an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator; and a second pump at an opposing end of the housing.

Description

An Improved Pump

Field of the Invention.

The invention relates generally to a pump and, more particularly, but not exclusively to a twin ended pump apparatus.

Background of the Invention.

In many countries, domestic mains water supplies are often installed as gravity fed systems whereby the water pressure of the installation is dependent on a height of a cold-water tank typically installed in the loft of the domestic premises. This can lead to generally low water pressure which may result in poorly performing showers for bathing and in slow running water from faucets, taps or the like.

With the very much increased installations of domestic showers for bathing over recent decades, there has been an increasing demand for booster pumps to boost the domestic mains water pressure or at least to boost the pressure of water in kitchens, bathrooms and showers.

Conventional booster pumps are typically arranged to simultaneously pump both heated and unheated water - normally referred to as ‘hot’ and ‘cold’ water. The reason for pumping both hot and cold water via the same pump is to achieve a balanced supply into the shower mixer valve thus preventing one of the hot water flow or the cold water flow overwhelming the other and thereby compromising the temperature adjustment parameters of the mixer valve.

GB24625392 and GB2506280 each disclose a twin ended water pressure booster pump for a shower or the like. The pump comprises an electric motor delivering rotational energy through a shaft. The shaft is driven to rotate by the rotor of the motor. The shaft extends to a first end of the motor through a first backplate assembly of a first pump chamber to drive an impeller in said first pump chamber to deliver fluid under pressure to a first outlet. The shaft also extends to an opposing end of the motor through a second backplate assembly of a second pump chamber to drive an impeller in said second pump chamber to deliver fluid under pressure to a second outlet. Suitable rotational seals are provided around the motor shaft where it extends through each respective backplate assembly. The foregoing prior art twin ended pump is typical of known twin ended pumps in that it utilizes a single electric motor having a shaft extending through each respective backplate assembly at the ends of the motor to drive hot water and cold water impellers simultaneously. As such, the impellers are driven at the same speed to create a fluid pressure at their respective outlets which is balanced, i.e. each at an equal pressure.

One of many problems which arise with such pumps, whether twin ended or single ended pumps, is leakage through the rotational seals. Rotational seals typically comprise a first fixed stationary part and a second part which rotates with the shaft. Consequently, the seal surface of the fixed stationary part and the seal surface of the second rotating part, which slide over each other to form the fluid seal, tend to wear against one another. Water in the pump chamber acts as a lubricant to reduce such wear, but, if the pump chamber runs dry, is starved of water, or the water in the chamber cavitates, the degree of wear can increase considerably leading to early failure of the rotational seal.

Failure of the rotational seal is itself problematic in that not only does it lead to leakage of the fluid, e.g. water, but, as booster pumps are typically installed in wall cavities behind installed shower mixer valve units or the like, repairing or replacing the booster pump can be difficult and require a degree of dismantling or demolition of existing structures behind which the booster pump is installed.

There are a number of different rotational seal types and these are normally retained on the shaft in differing ways, generally by the fitting of a retaining device around the shaft which holds a spring-loaded element of the rotational seal in tension, thus forcing the seal faces together. This gives rise to two further issues:

(i) the location point for the retaining device is a fixed location on the shaft, but the shaft needs to float to some degree within the motor assembly itself to accommodate manufacturing tolerances of the motor. As such, the spring-loaded element of the rotational seal will, by design, be itself unbalanced with the spring-loaded element being pressed more on one end than on an opposing end. Thus, one end is prone to leak more easily, and the other end is prone to wear out more easily.

(ii) any debris within the pump chamber and/or hard water deposits can cause foreign matter to become lodged between the surfaces of the rotational seal thereby damaging them. Furthermore, the build-up of debris and/or hard water deposits can force the seal surfaces apart over time which again leads to leaks and failure of the seals.

It would be useful if the rotational seals in booster pumps could be eliminated.

Known twin ended pumps of the type illustrated by GB24625392 and GB2506280 exhibit additional problems. For example, sometimes the pump chamber outlets of the pump are connected directly to respective hot and cold water faucets (taps). In the event that only one faucet is opened, water is required from only one pump chamber of the pump. The impeller of the other pump chamber not required to supply water is still driven by the motor shaft. This creates pressure and friction between the impeller and the water in the pump chamber and can cause the water to become heated and even in some cases to boil. As such the water temperate (be it the hot or cold side of the pump) may exceed the temperature rating of the pump seals which can, as a result, become hardened, damaged and then leak. Also, as the temperature increases in the pump chamber, the cavitation of the water increases which starves the rotational seals of the thin film of lubricating water between the seal surfaces leading to damage of the seal surfaces as hereinbefore described. In the event that the water in the pump chamber does boil to the point that the chamber becomes dry, the seal surfaces may become irreparably damaged in a very short timescale.

To overcome the foregoing issue, GB2517719 illustrates a solution comprising a fluid bypass connection between the two pump chambers. The fluid bypass connection fluidly connects one pump chamber to the other thus allowing water to flow from the non-flowing side of the pump to the flowing side of the pump. The fluid bypass connection should allow sufficient water to flow from one pump chamber to the other to prevent a full closed head running situation causing water to overheat or even boil in the non-flowing pump chamber. However, to fit the fluid bypass connection, a fluid bypass tube is connected to respective water fittings at each end of the pump and the water fittings are connected to respective pump chamber outlets thereby introducing several more potential leak paths in the pump installation.

It would be useful if the fluid bypass connection could be eliminated.

Objects of the Invention.

An object of the invention is to mitigate or obviate to some degree one or more problems associated with known single ended and twinned ended pumps. The above object is met by the combination of features of the main claims; the sub claims disclose further advantageous embodiments of the invention.

Another object of the invention is to provide an improved pump which reduces or eliminates the need for rotational shaft seals and/or reduces or eliminates the need for a fluid bypass connection.

One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.

Summary of the Invention.

The invention concerns a pump comprising an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber. The electric motor includes a stator for driving said rotor. The stator is preferably accommodated in a motor housing. The rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator/motor housing. Two such pumps can be connected together, or provided in a common housing, to provide a twin ended pump for pumping two separate fluid flows, especially hot and cold water for mixing in a bathing shower installation or the like. This negates the need to provide any rotational shaft seals in the pumps and/or any bypass fluid connections between the pump chambers.

In a first main aspect, the invention provides a twin ended pump apparatus comprising: a first pump at one end of a housing, said first pump comprising: an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator; and a second pump at an opposing end of the housing.

The electric motor of the first pump does not require any motor shaft to extend through said fluid-sealed boundary separating said pump chamber from the stator.

In a second main aspect, the invention provides a twin ended pump apparatus comprising: a first pump according having means for connecting said first pump to a second pump. For the first and second main aspects, the twin ended pump apparatus does not require a fluid by-pass connection between the pump chamber of the first pump and a pump chamber of the second pump.

The twin ended pump of the second main aspect does not require a common motor housing.

In a third main aspect, the invention provides a method of assembling a pump, the method comprising: arranging an impeller of the pump to be driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber when driven by the rotor; and providing a stator for driving said rotor; wherein said rotor is arranged on a pump chamber side of a fluid- sealed boundary separating said pump chamber from the stator.

In a fourth main aspect, the invention provides a method of assembling a twin ended pump apparatus, the method comprising: connecting a first pump to a second pump.

In a fifth main aspect of the invention, there is provided a method of operating a twin ended pump apparatus according to first or second main aspects, the method comprising the steps of: mixing a pumped heated fluid flow from the first pump with a pumped cold fluid flow from the second pump; and independently controlling operation of the first pump and the second pump to control at least one of a set pressure and/or a set temperature of a resulting mixed fluid flow.

Preferably, the method involves controlling the first and second pumps differentially to reduce or negate the need for a mixing valve or the like for mixing the pumped fluid flows from said first and second pumps. A simple mixing chamber may be used in replacement of a conventional mixing valve.

The summary of the invention does not necessarily disclose all the features essential for defining the invention; the invention may reside in a sub-combination of the disclosed features.

The forgoing has outlined fairly broadly the features of the present invention in order that the detailed description of the invention which follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It will be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the invention. Brief Description of the Drawings.

The foregoing and further features of the present invention will be apparent from the following description of preferred embodiments which are provided by way of example only in connection with the accompanying figures, of which:

Figure 1 is a perspective view of a twin ended pump apparatus in accordance with the invention;

Figure 2 is a partially exploded perspective view of the twin ended pump apparatus of

Fig. 1;

Figure 3 is a fully exploded side view of the twin ended pump apparatus of Fig. 1;

Figure 4 is a partially exploded side view of one end of the twin ended pump apparatus of Fig. 1;

Figure 5 is a perspective view of one embodiment of a pump chamber inner end plate for the twin ended pump apparatus of Fig. 1;

Figure 6 is block schematic diagram of a motor controller for the twin ended pump apparatus of Fig. 1; and

Figure 7 is a table showing savings in the materials of the present invention.

Description of Preferred Embodiments.

The following description is of preferred embodiments by way of example only and without limitation to the combination of features necessary for carrying the invention into effect.

Reference in this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments, but not other embodiments. It should be understood that some elements shown in the FIGS, may be implemented in various forms of hardware, software or combinations thereof. These elements may be implemented in a combination of hardware and software on one or more appropriately programmed general-purpose devices, which may include a processor, memory and input/output interfaces.

The present description illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope.

Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

Thus, for example, it will be appreciated by those skilled in the art that the block diagrams presented herein represent conceptual views of systems and devices embodying the principles of the invention.

The functions of the various elements shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor ("DSP") hardware, read-only memory ("ROM") for storing software, random access memory ("RAM"), and non-volatile storage.

References in the following description to a twin ended pump or a twin ended fluid pump are to be taken as references to a twin ended pump apparatus.

Referring to the drawings, shown is an embodiment of a twin ended fluid pump 10 in accordance with the invention. The pump 10 has a first end 10A and a second end 10B. At said first end 10A is a pump chamber 12 housing an impeller 14 for causing a fluid entering a fluid inlet 16 to flow out under pressure from a fluid outlet 18 of the pump chamber 12. The pump chamber 12 is defined between and bounded by a pump chamber inner end plate 20 and a pump chamber outer end plate 22. The outer end plate 22 comprises a volute for the pump chamber 12, although in other embodiments, a front face of the inner end plate 20 may fully or partially define said volute or the pump volute is defined by both the inner end plate 20 and the outer end plate 22.

Either or both of the inner end plate 20 and the outer end plate 22 may be formed as extruded or molded components. Either or both of the inner end plate 20 and the outer end plate 22 may be formed from high grade plastics material.

The inner end plate 20 is attached to a first end of a motor housing 24 such that a peripheral edge of a rear face of the inner end plate 20 forms a fluid-tight seal with a peripheral edge of the first end of the motor housing 24. A first “O” ring seal 26 or the like may be provided to ensure the integrity of the seal between the rear face of the inner end plate 20 and the first end of the motor housing 24. The outer end plate 22 is attached to the inner end plate 20 to thereby enclose the impeller 14 in the pump chamber 12. The arrangement is such that a peripheral edge of the rear face of the outer end plate 22 forms a fluid-tight seal with a peripheral edge of the front face of the inner end plate 20. A second “O” ring seal 28 or the like may be provided to ensure the integrity of the seal between the rear face of the outer end plate 22 and the front face of the inner end plate 20.

As can best be seen in Fig. 2, the outer end plate 22 can be secured by a set of bolts or screws 25 through the inner end plate 20 to the first end of the motor housing 24.

The pump 10 includes at least one motor unit 29 (Fig. 3) for driving the impeller 14. The motor unit 29 comprises the stator 30 which is positioned on a ‘dry’ side of the inner end plate 20 and the rotor 32 which is positioned on a ‘wet’ side of said inner end plate 20 and the motor housing 24, if present. As such, the inner end plate 20 defines a fluid-sealed boundary separating said pump chamber 12 from the stator 30/motor housing 24.

In this embodiment, the stator 30 has a plurality of stator windings 30A. The rotor 32 preferably comprises a permanent magnet rotor which, in operation, is driven by the electromagnetic fields of the stator windings 30A when such stator windings 30A are driven in a predefined sequence by a motor controller 100 (Fig. 6). Preferably, the motor unit 29 comprises a brushless direct current (BFDC) motor unit. The BFDC motor unit can be a six wire BLDC motor unit or a three wire BLDC motor unit. Use of a BLDC electric motor provides many advantages as will be more fully explained in the following description. The motor unit 29 can be considered, in effect, as comprising an electric motor in that it can be an “off the shelf’ electric motor. It will be understood, that, in other embodiments, other types of electric motors may be utilized in the pump 10 for driving the impeller 14 and thus the pump 10 in accordance with the invention is not limited to using BLDC motor units 29.

In the embodiment shown in the drawings, the stator 30 is accommodated in the first end of the motor housing 24.

The inner end plate 20 is preferably substantially cup shaped about a rotational axis of the rotor 32. A cup part 20A of the inner end plate 20 preferably extends into the first end of the motor housing 24 by an amount sufficient to support, accommodate or mount the stator 30 around an exterior cylindrical face of said cup part 20A. Alternatively, the stator 30 can be supported by or mounted in the motor housing 24. The rotor 32 is preferably accommodated within an interior volume of the cup part 20A of the inner end plate 20 such that the rotor 32 is positioned concentrically with the stator 30 when the pump 10 is assembled. The rotor 32 is therefore positioned for rotation within the cup part 20A when driven by the stator 30. Consequently, the rotor 32 is located on a ‘wet’ side of the fluid-sealed boundary defined by the inner end plate 20 which separates the pump chamber 12 from the stator 30/motor housing 24 and the stator 30 is positioned on a ‘dry’ side of said boundary.

It can be seen therefore that there is no need for the motor unit 29 to have a motor shaft which extends through the fluid-sealed boundary, i.e. through the inner end plate 20 separating the pump chamber 12 from the stator 30/motor housing 24.

To better facilitate rotation of the rotor 32, there may be provided a shaft or spigot 34 extending from an internal end face of the cylindrical cup part 20A of the inner end plate 20 as best seen in Fig. 5. In this embodiment, the rotor 32 is mounted to said shaft or spigot 34 for rotation about a longitudinal axis of the shaft or spigot 24. The shaft or spigot 34 may be fixed and thus non-rotating. In another arrangement, the shaft or spigot 34 may be mounted such as to be able to rotate about its longitudinal axis, i.e. the shaft or spigot 34 is rotatably mounted to the internal end face of the cup part 20A. In such arrangement, the rotor 32 is preferably keyed on or otherwise affixed to said shaft or spigot 34 to rotate therewith. In this latter arrangement, the impeller 14 may also be keyed on or otherwise affixed to said shaft or spigot 34 to rotate therewith. Thus, rotation of the rotor 32 causes rotation of the shaft or spigot 34 which in turn causes rotation of the impeller 14. In a yet alternative arrangement, one or more bearings may be provided in said cup part 20A of the inner end plate 20 for mounting the rotor 32 for rotation within said cup part 20A.

In some embodiments, the impeller 14 is assembled with the rotor 32 such that the impeller 14 is fixed to the rotor 32 for rotation therewith.

In some embodiments, the rotor 32 is formed integrally with the impeller 14. This may be as an extruded or molded component.

In light of the fact that the rotor 32 is on the wet side of the fluid sealed boundary separating the pump chamber 12 from the stator 30/motor housing 24, it is preferred that at least the rotor 32 is enveloped in a material which is not reactive, non-contaminating and/or non-polluting of the fluid to be pumped. More specifically, where the fluid to be pumped is potable water then it is preferred that at least the rotor 32 is enveloped in a material which meets a regulatory standard and/or quality standard for contact with potable water. For example, for the United Kingdom the material is preferably a Water Supply (Water Fittings) Regulations (WRAS) compliant material. Certain high wearing rubber compounds which are WRAS compliant may be used. Preferably, the rotor 32 and impeller 14, whether formed integrally as a single component or affixed to each other, are enveloped in the material which is not reactive, non-contaminating and/or non-polluting of the fluid to be pumped, e.g. enveloped in a material which meets a regulatory standard and/or quality standard for contact for potable water.

In the foregoing description of the twinned ended pump 10 depicted by the drawings, a pump unit 35 comprising the inner and outer end plates 20, 22, the impeller 14, the pump chamber 12 and its associated motor unit 29 comprising the stator 30, the rotor 32 and the motor housing, if present, has been described. It will be understood, however, that, in preferred embodiments, a pump unit 35 (including a motor unit 29) to be provided at the second end of the motor housing 24 is preferably identical to the pump unit 35 provided at the first end of the motor housing 24. Consequently, the pump 10 can be formed from two identical pump units 35 together with the motor housing 24 or by two pump units 35 without any common motor housing. In this latter embodiment, the two pump units 35 can be connected together at the ends of respective motor housings (not shown). One means of connecting the two pumps units 35 together is to provide said two pump units 35 with physical connecting means, preferably complimentary connecting means. The two pump units 35 could be connected such that they are connected with their axes of rotation in parallel or in alignment. Preferably, a connecting means of a first one of the pump units 35, denoted by dashed line 33 in Fig. 3, is provided at one end of the one of the pump units 35 and a connecting means 33 of the other one of the pump units 35 is provided at an opposing end of the other one of the pump units 35 such that, when said two pump units 35 are connected, they are connected with their axes of rotation in alignment. The connecting means 33 may be extruded or molded integrally on the exterior end faces of the inner end plates 20 of the two pump units 35 or on exterior end faces of motor housings of said two pump units 35. The connecting means 33 may comprise complimentary quarter turn lugs which enable said two pump units 35 to be quickly assembled together even within a common motor housing 24 in the arrangement where said connecting means 33 are provided on the exterior end faces of the inner end plates 20 of the two pump units 35.

Two such pump units 35 can be connected together, or provided in a common housing 24, to provide a twin ended pump 10 for pumping two separate fluid flows, especially hot and cold water for mixing in a bathing shower installation or the like. This negates the need to provide any rotational shaft seals in the motor units 29 or any bypass fluid connections between the pump chambers of the pump units 35.

Where the pump 10 is formed from two identical pump units 35 including identical motor units 29, it will be understood that only one design and configuration of pump unit 35/motor unit 29 is required which provides savings and more versatility. The rotors 32 of the identical motor units 29 will rotate counter to each other when arranged in the embodiments of the pump 10 shown in the drawings.

It will also be understood that it is possible to form a single ended pump from the pump 10 by providing said pump with only one pump unit 35/motor unit 29. In such a case, the motor housing 24, if included, can be shortened to accommodate a single motor stator 30 within the shortened motor housing 24 and with an opposing open end of the motor housing 24 being closed by a motor end plate (not shown). Thus, only one design and configuration of pump unit 35/motor unit 29 is required to assemble single ended pumps in accordance with the invention and twin ended pumps 10 in accordance with the invention. The top part of Fig. 3 can be considered as illustrating one embodiment of a single ended pump in accordance with the invention.

For any of the embodiments of the twin ended pump 10 as described herein, each pump unit 35 may be controlled independently of the other pump unit 35.

As shown in Fig. 6, a single motor controller 100 may be provided for independently controlling the two pump units 35. Additionally, or alternatively, separate motor controllers 100A, 100B may be provided to control the two pump units 35.

The motor controllers 100, 100A, 100B may each comprise a processor 102, 102A, 102B and a memory 104, 104A, 104B. The memories 104, 104A, 104B store machine readable instructions which, when executed by the processors 102, 102A, 102B, cause the processors 102, 102A, 102B to control, either singly or in combination, the pump units 35 in accordance with the methods described herein.

In known twin ended pumps using a single motor to drive the twin impellers in their respective pump chambers this results in a same pressure of fluid exiting the respective pump chamber outlets. Where such a pump is employed in a system such as a domestic shower installation for pumping hot and cold water, it is necessary to a mixing valve or the like to mix portions of the balanced pressure pumped hot and cold water flows to achieve a desired temperature of a mixer output flow from the mixed hot and cold water flows. However, mixing valves are very variable in efficiency and often the temperature set at the mixing valve vary considerably resulting in a poor showering experience for a user.

By enabling the twin impellers 14 of the twin ended pump 10 in accordance with the invention to be operated independently, variably and in unison enables much better control of mixed hot and cold water flows. In fact, it is possible to provide flows of mixed water at desired set temperatures and/or at desired set pressures using just the control of the independently operating impellers 14 and a simple mixing chamber (not shown) and thus it is possible to reduce the complexity or even eliminate the need for a mixing valve or like device or system.

For example, the operation of each pump unit 35 can be separately controlled by separately controlling the respective speeds of the impellers 14 to achieve a first set pressure fluid output when the pumped fluid output of the first pump unit 35 is mixed with the pumped fluid output of the second pump unit 35. Where the first pump unit 35 is arranged to pump heated fluid, e.g. hot water, and the second pump unit 35 is arranged to pump unheated fluid, e.g. old water, the operation of each pump unit 35 can be separately controlled by separately controlling the respective speeds of the impellers 14 to achieve a first set pressure fluid output at a first set temperature when the pumped heated fluid output of the first pump unit 35 is mixed with the pumped unheated fluid output of the second pump unit 35.

The operating speed of each pump unit 35 can be changed in tandem to reach a second set pressure fluid output, i.e. the speeds of the impellers can be increased or decreased proportionally in tandem to reach said second set pressure fluid output. The operating speed of each pump unit 35 can be changed in tandem to reach a second set pressure fluid output at said first set temperature in a similar manner.

Furthermore, the operating speed of each pump unit 35 can be changed differentially to reach a second set temperature when the pumped heated fluid output of the first pump unit 35 is mixed with the pumped unheated fluid output of the second pump unit 35. The operating speed of each pump unit 35 can be changed differentially to reach a second set temperature at a set pressure fluid output when the pumped heated fluid output of the first pump unit 35 is mixed with the pumped unheated fluid output of the second pump unit 35. In either case, changing the speeds of the impellers 14 differentially can allow the temperature of the mixed flow to be raised or lowered whilst keeping the pressure of the mixed flow at the same level as previously.

For example, with hot water being pumped through the first pump unit at say 65 degrees C and cold water being pumped through the second pump unit 35 at say 5 degrees C, it is possible, by changing the speeds of the independent impellers 14 differentially, to mix water to a temperature anywhere within a range of 5 to 65 degrees C. For example, where the speed of the impeller 14 of the cold water pump unit 35 is say X revolutions per minute (rpm) and the speed of the impeller 14 of the hot water pump unit 35 is say Y rpm to result in a mixed water temperature of say 45 degrees C then the relative speeds of the two impellers 14 can be differentially changed to respectively increase or decrease the hot and cold water flows to achieve a new desired set temperature. If the speeds of the two impellers are then increased or decreased in tandem this will result in an increased or decreased set pressure of the mixed water flow. To assist the foregoing control of two pump units 35, it is preferred that pump chamber inlet and/or outlet flow sensors 106 and/or inlet and/or outlet temperature sensors 108 are included or associated with the pump units 35. The inlet and/or outlet flow sensors 106 and/or the inlet and/or outlet temperature sensors 108 may be arranged to feedback flow and temperatures data to one or more of the motor controllers 100, 100A, 100B to thereby vary the individual and/or combined speeds of the impellers as required and directed by said sensor data and in response to use inputs which may be inputted by a user to one of the motor controllers 100, 100A, 100B and which may be varied by a user over time.

The invention also provides a method of assembling a pump 10. The method comprises: arranging an impeller 14 of the pump 10 to be driven by a rotor 32 of an electric motor unit 29, the impeller 14 causing a fluid to flow out of a pump chamber 12 when driven by the rotor 32. The stator 30 may be accommodated a motor housing 24. The rotor 32 is arranged on a pump chamber side of a fluid- sealed boundary 20 separating said pump chamber 12 from the stator 30/motor housing 24.

The invention provides another method of assembling a pump 10. This method comprises: connecting a first pump unit 35 to a second pump unit 35.

Each pump unit 25 is therefore able to be controlled independently of the other pump unit 35. The speed of the impeller 14 of one pump unit 35 can be changed differentially with respect to the speed of the impeller 14 of the other pump unit 35.

The invention provides a method of operating a twin ended pump 10, the method comprising the steps of: mixing a pumped heated fluid flow from the first pump unit 35 with a pumped cold fluid flow from the second pump unit 35; and independently controlling operation of the first pump unit 35 and the second pump unit 35 to control at least one of a set pressure and/or a set temperature of a resulting mixed fluid flow. Independently controlling operation of the first pump unit 35 and the second pump unit 35 may comprise independently controlling the speeds of the impellers 14 of the first pump unit 35 and the second pumps unit 35, although their speeds may be changed proportionally in unison to change to a different desired pressure of mixed fluid flow. The method preferably involves controlling the first and second pumps units 35 differentially to reduce or negate the need for a mixing valve or the like for mixing the pumped fluid flows from said first and second pumps units 35. A simple mixing chamber may be used in replacement of a conventional mixing valve. The following is an example of the benefits of using two motor units 29 in the pump 10 motor compared to a conventional motor as exemplified by prior art references GB24625392 and GB2506280.

A traditional brushed or brushless electric motor may run at 12V DC at 3A, providing (for example) 60mNm of output torque at 6000 rpm (628 rad/s). This may be referred to as original motor A "OM-A". The present invention replaces the single OM-A motor, referenced above, with two smaller motor units 29 with the aim of producing the same or similar overall mechanical output. For example, each of the two smaller motor units 29 could comprise motors operating at 30mNm at 6000 rpm (one-half of the output torque at the same speed). By summing the output torques at the same speed, the same overall output as the original single motor system OM-A described above, would be provided.

It will be noted that each new smaller sub-motor (which we will referred to as NM- 1 to NM-2) will each only be required to carry one-half of the current, that is 1.5A at 12V DC. It will also be noted that the rotor wire needs only to be one-half of the thickness in order to carry this smaller current. As such, the amount of wire mass required for the two individual motor units 29 compared with the original motor OM-A is approximately 37% less (Figure 7), which is a considerable useful but unexpected improvement.

Because the power requirement of each motor unit 29 is half of the equivalent prior art motor OM-A, the magnetic flux across the motor unit stator coils is also lower than the equivalent prior art motor OM-A. In other words, each of NM-1 to NM2 requires one half of the flux (and thus one half of the magnetized material).

In addition, the rotors of NM-1 and NM-2 can be made smaller than OM-A. Therefore, the gap required between the stators in order to surround the rotor of each motor unit 29 is reduced. As well as requiring one half of the flux, each motor of the motor units 29 only requires it to be established across a smaller gap. This leads to a further benefit, by an inverse square law relative to the amount of magnetic material required. Therefore, each of NM-1 and NM-2 actually requires less than one -half of the magnetic material in OM-A. In reality, the approximate size and weight reduction of the total magnet mass is approximately 26% (Figure 7). In a similar system which utilizes electro -magnets to establish the magnetic field of the stator, a similar power reduction into the stator coils would also be realized. This is because the strength of the magnetic field is dependent upon the power within the electromagnetic coil, and the air gap, both of which can be reduced for smaller motors.

Turning to Figure 7, various combinations of motors are shown in tabular form. The columns are as follows:

Column A Number of sub-motors Column B Potential difference across each sub-motor input Column C Current used per sub-motor Column D Output torque per sub-motor Column E Summed output torque Column F Percentage copper saving on rotor wire material Column G Percentage saving on magnetic material in stators.

Because the diameter of the rotor wire decreases the smaller the rotor is, the cross- sectional area also decreases and hence the amount of copper required.

The total torque output is always 60Nm (at the same speed for each arrangement). With the reduction in current comes the associated reduction in core wire diameter, and an associated reduction in cross sectional area in mm² (which is proportional to the copper mass used). The final column represents the reduction in copper material required. The present example uses 2 motors and as such realizes a reduction of about 26%.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims. In the claims hereof, any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements that performs that function or b) software in any form, including, therefore, firmware, microcode or the like, combined with appropriate circuitry for executing that software to perform the function. The invention as defined by such claims resides in the fact that the functionalities provided by the various recited means are combined and brought together in the manner which the claims call for. It is thus regarded that any means that can provide those functionalities are equivalent to those shown herein.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art.

Claims

Claims.

1. A twin ended pump apparatus comprising: a housing; a first pump at one end of the housing, said first pump comprising an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator; and a second pump at an opposing end of the housing.

2. The twin ended pump apparatus of claim 1, wherein the second pump comprises at the opposing end of the housing an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator.

3. The twin ended pump apparatus of claim 1, wherein the electric motor of the first pump does not have a motor shaft extending through said fluid- sealed boundary separating said pump chamber from the stator.

4. The twin ended pump apparatus of claim 1, wherein the fluid-sealed boundary separating said pump chamber from the stator of said first pump is defined by a pump chamber inner end plate, the pump chamber inner end plate being substantially cup-shaped about a rotational axis of the rotor.

5. The twin ended pump apparatus of claim 4, wherein a cup part of the pump chamber inner end plate extends into the housing by an amount sufficient to mount the motor stator around an exterior cylindrical face of said cup part.

6. The twin ended pump apparatus of claim 4 or claim 5, wherein said rotor is accommodated within an interior volume of a cup part of the pump chamber inner end plate such that the rotor is positioned concentrically with the stator for rotation within the cup part when driven by the stator.

7. The twin ended pump apparatus of claim 6, wherein said cup part has a shaft or spigot extending from an internal end face, said rotor being mounted to said shaft or spigot for rotation about an axis of the shaft or spigot.

8. The twin ended pump apparatus of claim 7, wherein said rotor is keyed to said shaft to cause said shaft to rotate with the rotor, said shaft being rotatably mounted to the internal end face of the cup part.

9. The twin ended pump apparatus of any one of the preceding claims, wherein at least the rotor is enveloped in a material which is not reactive, non-contaminating and/or non polluting of the fluid to be pumped.

10. The twin ended pump apparatus of any one of the preceding claims, wherein the fluid to be pumped is potable water and the rotor is enveloped in a material which meets a regulatory standard and/or a quality standard for contact with potable water.

11. The twin ended pump apparatus of any one of the preceding claims, wherein the stator and rotor comprise a brushless direct current (BLDC) motor unit.

12. The twin ended pump apparatus of any one of the preceding claims, wherein each pump is controlled independently of the other pump.

13. The twin ended pump apparatus of any one of the preceding claims, wherein the operation of each pump can be controlled to achieve a first set pressure fluid output when the pumped fluid output of the first pump is mixed with the pumped fluid output of the second pump.

14. The twin ended pump apparatus of claim 13, wherein the first pump is arranged to pump heated fluid and the second pump is arranged to pump unheated fluid and wherein the operation of each pump can be controlled to achieve a first set pressure fluid output at a first set temperature when the pumped heated fluid output of the first pump is mixed with the pumped unheated fluid output of the second pump.

15. The twin ended pump apparatus of claim 13 or claim 14, wherein the operating speed of each pump can be changed in tandem to reach a second set pressure fluid output when the pumped fluid output of the first pump is mixed with the pumped fluid output of the second pump.

16. The twin ended pump apparatus of claim 15, wherein the operating speed of each pump can be changed in tandem to reach a second set pressure fluid output at said first set temperature when the pumped heated fluid output of the first pump is mixed with the pumped unheated fluid output of the second pump.

17. The twin ended pump apparatus of claim 15, wherein the operating speed of each pump can be changed differentially to reach a second set temperature when the pumped heated fluid output of the first pump is mixed with the pumped unheated fluid output of the second pump.

18. The twin ended pump apparatus of claim 15, wherein the operating speed of each pump can be changed differentially to reach a second set temperature at a set pressure fluid output when the pumped heated fluid output of the first pump is mixed with the pumped unheated fluid output of the second pump.

19. The twin ended pump apparatus of any one of the preceding claims, wherein the twin ended pump does not require a fluid by-pass connection between the pump chamber of the first pump and the pump chamber of the second pump.

20. The twin ended pump apparatus of any one of the preceding claims, wherein the end face of the cup part of the pump chamber inner end plate of the first pump has means for attaching to an end face of a cup part of a pump chamber inner end plate of the second pump.

21. The twin ended pump apparatus of any one of the preceding claims, wherein the first pump has a first drive controller and the second pump has a second drive controller.

22. The twin ended pump apparatus of any one of the preceding claims having means for connecting said first pump to said second pump.

23. The twin ended pump apparatus of claim 22, wherein the connecting means of the first pump are complimentary to the connecting means of the second pump.

24. The twin ended pump apparatus of claim 21 or claim 23, wherein said first pump and said second pump are connected with their axes of rotation in alignment or in parallel.

25. The twin ended pump apparatus of claim 22 or claim 23, wherein the connecting means of the first pump are provided at one end of the first pump and the connecting means of the second pump are provided at an opposing end of the second pump such that, when said first pump and said second pump are connected, they are connected with their axes of rotation in alignment.

26. A method of assembling a twin ended pump apparatus, the method comprising: connecting a first pump to a second pump within a housing such that at least the first pump has an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid-sealed boundary separating said pump chamber from the stator.

27. A method of operating a twin ended pump apparatus according to any one of claims 1 to 25, comprising the steps of: mixing a pumped heated fluid flow from the first pump with a pumped cold fluid flow from the second pump; independently controlling operation of the first pump and the second pump to control at least one of a set pressure and/or a set temperature of a resulting mixed fluid flow.

28. The method of claim 27 including differentially controlling the first and second pumps to obtain at least one of a set pressure and/or a set temperature of a resulting mixed fluid flow.

29. A twin ended pump apparatus comprising: a first pump having a first housing and comprising an impeller driven by a rotor of an electric motor, said impeller causing a fluid to flow out of a pump chamber, said electric motor including a stator for driving said rotor, wherein said rotor is arranged on a pump chamber side of a fluid- sealed boundary separating said pump chamber from the stator; and a second pump having a second housing; wherein the first housing of the first pump is connected to the second housing of the second pump and the first and second pumps are controlled to operate by a single controller.