WO2020031017A1

WO2020031017A1 - A system for water cooled induction drive suction booster pump

Info

Publication number: WO2020031017A1
Application number: PCT/IB2019/056448
Authority: WO
Inventors: Kabir BHANDARI; Radu GOGOANA
Original assignee: Padmini Vna Mechatronics Pvt. Ltd.
Priority date: 2018-07-28
Filing date: 2019-07-29
Publication date: 2020-02-13
Also published as: CN110972487A

Abstract

The present invention relates to booster pumps utilized in reverse-osmosis for water purification appliances. The invention provides a system for fluid cooling the pump motor compatible to variety of motors and providing greater appliance performance. It provides a system for a fluid cooled induction drive suction booster pump; by providing cooling to a sealed water pump motor by cooling at least one portion of the sealed booster pump motor via a fluid preferably coolant liquid or water.

Description

“A SYSTEM FOR WATER COOLED INDUCTION DRIVE SUCTION BOOSTER

PUMP”

FIELD OF THE INVENTION

The present invention relates to an improved booster pump generally utilized in reverse- osmosis for water purification applications. More specifically, the present invention provides a booster pump with an improved orientation and motor cooling channel(s) to improve its performance and to remove heat from the booster pump and is also compatible to variety of motors thus providing greater appliance performance.

BACKGROUND OF THE INVENTION

The majority of household reverse-osmosis water purifiers in India use booster pumps for pressurizing the water through a reverse-osmosis membrane for desalination. The motors used for driving these pumps are typically permanent-magnet brushed DC motors with input voltages ranging from 12 to 48 volts. Permanent magnet DC motors tend to be approximately 65-80% efficient which means that they do not require external cooling in these applications. The shaft power output of these pumps is approximately 15 watts, so only 7-10 watts ends up needing to be dissipated. Water purifier cabinets tend to be sealed without ventilation for cooling. This thermal limitation is one of the main reasons why permanent magnet brushed DC motors are used in this application because of their relatively high efficiency and low cooling requirement.

However, DC motors require a power supply to convert the 220 volt AC household power to DC, which requires either a transformer-based power supply or an electronically controlled switching power supply. These power supplies add significant cost to the bill-of-materials for producing a household water purifier and also adds significant warranty risk to the manufacturer as the power supply tends to be the first thing that fails in the event of a power spike in the mains electrical supply. Single-phase AC motors which are commonly used in household appliances ranging from table fans to air-conditioning compressor motors, do not require such power supplies to operate and can connect to the mains outlets directly. However, they are far less efficient converting only approximately 25-55% of their input electrical power to mechanical shaft output power. This means that they need active cooling in order to prevent from overheating and burning out their electrical windings. In household fans, this cooling is provided by air that is rushing past the motor’s windings. In household air conditioners, this cooling is provided by the gas that is flowing through the motor inside the hermetically sealed compressor. However, the sealed cabinets of water purifiers do not allow for outside airflow to cool the motor.

Water purifiers, however, have running water flowing through them which can be used for liquid-cooling the pump motor. However, in these domestic appliance applications, there is constantly the risk of electrocution; if the water comes into contact with high- voltage components inside the water purifier, there is a risk of electric shock to the user who may be touching the drinking water that is coming out of the water purifier. Therefore, the water pathway for cooling the motor must be electrically insulated from the water that is flowing through it. Water cooling these pump motors has a further benefit that it allows for the use of more powerful motors. As motor power increases, the amount of heat dissipated typically also increases. By water cooling, the heat dissipation limit is greatly increased, allowing for more powerful pump motors and therefore more powerful pumps. The more powerful pumps can flow water at higher rates, create higher pressures, or provide higher pressure differentials. Most water purifiers on the market today require a minimum inlet water pressure to operate so pumps take inlet water at, for example, 5 psi and pressurize it to 70 psi for the RO membrane. A more powerful pump can operate at negative inlet pressures, and provide -5 psi to +70 psi of pressure differential. This eliminates the need for a minimum inlet water pressure and therefore allows water purifiers to suck water from a bucket on the ground, which enables water purifiers to be used in homes without adequate piped water pressure: for example, rural single-story homes.

Cooling is very important for any pump to remove the heat generated but at the same time orientation of pump heads is also important to improve the overall performance of the pump. Conventional pump heads available in the market has two chambers at the bottom and one chamber at top. During pumping, water first fills in the chambers in the bottom during suction but the chamber at the top does not fill properly because the suction capacity of the pump in bottom two chambers is more than coming water into the pump. Therefore only two chambers are fully utilized when the pump is horizontal. These types of pump only work at full performance when they are installed vertically.

US6637539B2 discloses all terrain vehicle including an engine having a clutch housing and a clutch cover sealably connected to the clutch housing to provide a space for containing oil therebetween, at least one of the clutch housing and the clutch cover including a bottom wall having at least one coolant-fillable cooling channel within the thickness of the bottom wall such that the clutch housing and the clutch cover cooperate to provide a coolant-fillable space therebetween the coolant-fillable space being provided to cool the oil within the space between the clutch housing and the clutch cover. The main drawback of the invention is that the coolant is only provided to cool the oil and not the engine.

US3711731A discloses an apparatus for supplying cooling water to the cooling channels of an electrical machine rotor having a rotor shaft has an inlet chamber surrounding the rotor shaft in liquid-tight relation to the ambient and an outlet chamber communicating with the rotor channels for receiving the cooling water, the latter being heated and reduced in pressure by its passage through the rotor channels. The outlet chamber surrounds the rotor shaft in liquid tight relation to the ambient. A primary circulation path for conveying the cooling water connects between the outlet chamber and the inlet chamber for conducting the cooling water between these chambers. A pump is provided for supplying the cooling water to the inlet chamber under pressure and for urging the same through the primary conveying path. The main drawback of the invention is that motor is provided to cool the electric machine through cooling water but there is no such provision for cooling the motor itself.

Therefore, there is a technological gap that requires water-cooling of the motor for reverse-osmosis water purifier pumps to both reduce cost by eliminating the need for a DC power supply and also boost performance by allowing for suction/booster operation with a design that electrically insulates the water pathway from the metallic components of the motor. There is also a need for such orientation of pump head that allows the pump to work in both horizontal and vertical directions as well as leads to an improved performance of the pump. OBJECT OF THE INVENTION

The main object of the invention is to provide an improved booster pump with an improved orientation and motor cooling channel(s) to improve its performance and to remove heat from its housing. Yet another object of the invention is to allow an improved booster pump to be fluid cooled and used in water purification appliances and also to provide an electrically insulated fluid pathway from the booster pump to prevent electrocution.

Yet another object of the invention is to provide an improved orientation in the head assembly of the improved booster pump to improve its performance. Still another object of the invention is to provide an improved booster pump with an improved orientation to increase its open flow rate by 10-11% and flow rate by 45-46% when back pressure is applied and motor cooling channel(s) to cool the booster pump simultaneously.

SUMMARY OF THE INVENTION

The present invention relates to an improved booster pump generally utilized in reverse- osmosis for water purification appliances. More specifically, the present invention provides an improved booster pump with an improved orientation and motor cooling channel(s) to improve its performance and to remove heat from the improved booster pump and be compatible to variety of motors thus providing greater appliance performance.

In a main embodiment, the present invention provides an improved booster pump with motor cooling channel(s) comprising of a head assembly, an end plate and a motor housing assembly. The motor housing assembly comprising of a motor housing is assembled to said head assembly. The end plate is either inbuilt in said motor housing assembly or assembled in front of the motor housing. The head assembly comprises of a head cap, a pump head and a cooling channel cover. The head cap is attached to the pump head forming as a cover to protect said pump head from dirt, dust and other environmental conditions. The head cap along with the pump head is then attached to the cooling channel cover and the cooling channel cover gets fitted into the end plate of the motor housing assembly to complete the assembly of booster pump. The end plate has motor cooling channel(s) that are continuously fed with fluid which thermally removes away heat from the motor housing assembly or motor housing via convection. The pump head has a plurality of fluid booster chambers to fill the fluid through each fluid booster chambers thus improving the performance of the booster pump.

The head assembly has an inlet and an outlet for fluid provided on the cooling channel cover and fluid enters the motor cooling channel(s) through its inlet and pumped out from its outlet. The fluid pumped out from the motor cooling channel(s) enters into the inlet of the head cap and the fluid is further pumped out from the outlet of the head cap into the water purifier.

In an alternative embodiment, the present invention provides an improved booster pump with a head assembly having a plurality of fluid booster chambers in its pump head. The fluid booster chambers are oriented in such a way that two fluid booster chambers are positioned parallel to mounting of said booster pump and one fluid booster chamber is positioned below the two fluid booster chambers while mounted horizontally to collect fluid in each fluid booster chambers so as to improve the performance of the booster pump while mounted horizontally. The head assembly has an inlet and outlet for fluid provided on the head cap. The orientation of the fluid booster chambers allows said booster pump to work in vertical and horizontal position. The improved performance of said booster pump includes but not limited to increase in the open flow rate and flow rate with back pressure.

In an alternative embodiment, the present invention provides an improved booster pump having a motor cooling channel(s) in the end plate of motor housing assembly. The end plate is either inbuilt in said motor housing assembly or assembled in front of the motor housing. The motor cooling channel(s) are continuously fed with fluid which thermally removes away heat from the motor housing assembly or motor housing via convection. The head assembly has an inlet and an outlet for fluid provided on the cooling channel cover and motor cooling channel(s) on the end plate. The fluid resulting due to thermal conduction from the pump housing via conduction is pumped through the pump head of the head assembly. BRIEF DESCRIPTION OF THE DRAWINGS

The object of the invention may be understood in more details and more particularly description of the invention briefly summarized above by reference to certain embodiments thereof which are illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective equivalent embodiments. The present invention will be described with reference to the following drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention:

Figure 1 provides an exploded view of the head assembly of an improved booster pump in accordance with an embodiment of the present invention. Figure 2(a), 2(b) and 2(c) provides a perspective view of the head assembly showing orientation and motor cooling channel(s) of an improved booster pump and also shows fluid flow channel in the booster pump and pump head orientation in accordance with an embodiment of the present invention.

Figure 3 provides an exploded view of an improved booster pump with an improved head assembly in accordance with an alternative embodiment of the present invention.

Figure 4(a), 4(b) and 4(c) provides a perspective view of an improved booster pump showing motor cooling channel(s), an exploded view of the pump head with end plate showing motor cooling channel(s) and a perspective view of a head assembly in accordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art. The present invention provides an improved booster pump generally utilized in reverse- osmosis for water purification appliances. More specifically, the present invention provides an improved booster pump with an improved orientation and motor cooling channel(s) to improve its performance and to remove heat from the booster pump and is compatible to variety of motors thus providing greater appliance performance. In a main embodiment, the present invention provides an improved booster pump with motor cooling channel(s) comprising of a head assembly and a motor housing assembly. The motor housing assembly comprising of a motor housing is assembled to said head assembly. The end plate is either inbuilt in said motor housing assembly or assembled in front of the motor housing. The head assembly comprises of a head cap, a pump head and a cooling channel cover. The head cap is attached to the pump head forming a cover to protect said pump head from dirt, dust and other environmental conditions. The head cap along with the pump head is then attached to the cooling channel cover and the cooling channel cover gets fitted to the end plate of the motor housing assembly to complete the assembly of booster pump. The end plate has motor cooling channel(s) that are continuously fed with fluid which thermally removes away heat from the motor housing assembly or motor housing via convection. The pump head has a plurality of fluid booster chambers to fill the fluid through each fluid booster chambers thus improving the performance of the booster pump.

In an alternative embodiment, the present invention provides an improved booster pump with a head assembly having a plurality of fluid booster chambers in its pump head. The fluid booster chambers are oriented in such a way that two fluid booster chambers are positioned parallel to mounting of said booster pump and one fluid booster chamber is positioned below the two fluid booster chambers while mounted horizontally to collect fluid in each fluid booster chambers so as to improve the performance of the improved booster pump while mounted horizontally. The head assembly has an inlet and outlet for fluid provided on the head cap. The orientation of the fluid booster chambers allows said improved booster pump to work in vertical and horizontal position. The performance of said booster pump includes but not limited to increase in the open flow rate and flow rate with back pressure and the improved performance is defined as increase in open flow rate in the range of 10-11% and flow rate in the range of 45-46% when back pressure is applied to said improved booster pump.

In an alternative embodiment, the present invention provides an improved booster pump with having a motor cooling channel(s) in the end plate of motor housing assembly. The end plate is either inbuilt in said motor housing assembly or assembled in front of the motor housing. The motor cooling channel(s) are continuously fed with fluid which thermally removes away heat from the motor housing assembly or motor housing via convection. The head assembly has an inlet and an outlet for fluid provided on the cooling channel cover and motor cooling channel(s) on the end plate of motor housing assembly. The fluid resulting due to thermal conduction from the motor housing assembly or motor housing via conduction is pumped through the pump head of the head assembly.

The present invention provides the cooling of the improved booster pump by cooling at least one portion of the sealed booster pump via fluid not limited to coolant liquid or water. The present invention alleviates the problem wherein the pump housing is made from a thermally conductive material. The thermally conductive material allows the booster pump to be cooled via conduction; by conducting the heat away from the pump housing to an end plate.

The fluid flowing through motor cooling channel(s) which is within the end plate cools the motor housing assembly or motor housing via convection and thermally conducts heat away from the improved booster pump via conduction. The purpose of the fluid cooling system is to keep the improved booster pump cool during operation. A non- conductive coating is on the motor cooling channel(s) and end plate that electrically insulates the fluid inside the motor cooling channel(s) from the metallic part of the improved booster pump.

Now referring to Figure 1, exploded view of the pump head assembly of an improved booster pump is shown. Said booster pump has a head assembly 100 and a motor housing assembly 99. The head assembly 100 comprises of a head cap 103, a pump head 108 and a cooling channel cover 102. The motor housing assembly 99 having an end plate 101 that has motor cooling channel(s) 104. The head cap 103 fits to the pump head 108 forming the cover of said pump head 108. The cooling channel cover 102 is fixed to cover the end plate 101 The head assembly 100 is press fitted to the motor housing assembly 99 to complete the assembly of improved booster pump. The pump head 108 has a plurality of fluid booster chambers 113a, 113b, 113c which gets fully filled with fluid. The fluid booster chambers 113a, 113b, 113c are oriented in such a way that two fluid booster chambers 113a, 113b are positioned parallel to mounting of said improved booster pump and one fluid booster chamber 113c is positioned below the two fluid booster chambers 113a and 113b while mounted horizontally. In this orientation, fluid starts filling from the bottom of the said fluid booster chamber 113c and occupies till the top of the two fluid booster collection chambers 113a, 113b thus filling all the fluid booster chambers 113a, 113b, 113c of the pump head 108. This orientation increases the open flow rate to 10.76% and 45.94% when a back pressure is applied to the booster pump while mounted horizontally as shown in Table 1. The end plate 101 has motor cooling channel(s) 104 which thermally conduct away heat from the motor housing assembly 99 or motor housing 101a via conduction.

Table 1 shows the performance analysis of the booster pump with a conventional orientation and with an improved orientation. The booster pump having conventional orientation as already known in the prior art has two water collection chambers on the bottom of the pump head and one water collection chamber on the top of the pump head of the booster pump. This conventional orientation allows filling of the bottom two water collection chambers and top water collection chamber does not fill properly. The conventional orientation allows the booster pump to work in horizontal direction. The improved orientation has two fluid booster chambers positioned parallel to mounting of said booster pump and one fluid booster chamber positioned below the two fluid booster chambers while mounted horizontally. This improved orientation allows the filling of all the fluid booster chambers and allows the booster pump to work in both horizontal and vertical direction. The open flow rate when calculated gives results for conventional and improved orientation. The open flow rate comes out to be 2.06 TPM and flow rate comes out to be 1.35 TPM when back pressure is applied. The open flow rate increases to 10.76% and flow rate with back pressure increases to 45.94% while mounted horizontally as compared to conventional orientation.

TABLE 1

Performance Analysis

Now referring to Figure 2(a), the present invention shows the improved booster pump having head assembly 100 and motor housing assembly 99. The head cap 103 along with the pump head (not shown) is affixed to the cooling channel cover (not shown) covering and fitted to the end plate 101 of the motor housing assembly 99 to complete the assembly of the improved booster pump. The end plate is either inbuilt in said motor housing assembly or assembled in front of the motor housing. Figure 2(b) shows the fluid flow from the motor cooling channel(s) 104 to the pump head 108. The fluid enters from the inlet 104a of the cooling channel cover 102 traverse through the motor cooling channel(s) 104 and flows out of the outlet 104b of the cooling channel cover 102. The fluid flowing out of the outlet 104b enters the inlet 111 of the head cap 103 fills the fluid booster chambers 113a, 113b, 113c of the pump head 108 and comes out from the outlet 112 of the head cap 103. In this way, the fluid flow is channelized through the motor cooling channel(s) 104 to cool the motor housing assembly 99 of the booster pump and flows through the fluid booster chambers 113a, 113b, 113c of the pump head 108 to improve the flow rate of booster pump by 10.76% and 45.94% when a back pressure is applied to said booster pump. Figure 2(c) shows the orientation of fluid booster chambers 113a, 113b, 113c of the pump head 108. The pump head 108 having head cap 103 has an inlet 111 to allow the fluid to enter said fluid booster chambers 113a, 113b, 113c and an outlet 112 to pump out the fluid. The orientation of fluid booster chambers 113a, 113b, 113c is such that two fluid booster chambers 113a, 113b are positioned parallel to mounting of said booster pump and one fluid booster water collection chamber 113c is positioned below the two fluid booster chambers 113a and 113b while mounted horizontally. The fluid flowing out through the outlet 104b of the cooling channel cover 102 of the booster pump enters the pump head 108 through the inlet 112 and fills the fluid booster chambers 113c from the bottom of the pump head and starts filling it till the top of the fluid booster chambersll3a and 113b. The fluid is finally pumped out from the outlet 112 of the head cap 103. This improved orientation increases the open flow rate to 10.76% and 45.94% when a back pressure of 70 psi is applied to the booster pump while mounted horizontally. The orientation allows the booster pump to work in horizontal and vertical direction.

Figure 3 shows an alternative embodiment of the booster pump with the head assembly 100 having fluid booster chambers on the pump head 108. The head assembly 100 is assembled to the motor housing assembly 99 having an end plate 101 to form a complete assembly of the improved booster pump. The pump head 108 is covered with a head cap 103 to protect said pump head 108 from dirt, dust and other environmental conditions.

The pump head 108 has a plurality of fluid booster chambers 113a, 113b, 113c to fill the fluid from bottom to top of the pump head 108. The orientation allows an improved open flow rate to 10.76% and 45.94% when back pressure is applied to said booster pump while mounted horizontally. Figure 4(a) shows a perspective view of an alternative embodiment of the improved booster pump showing motor cooling channel(s). The head assembly 100 is shown with an inlet for fluid 104a provided on the cooling channel cover 102 and feeding motor cooling channel(s) 104 on the end plate 101. The fluid coming out from the outlet 104b of the cooling channel cover 102 resulting due to thermal conduction from the motor housing assembly 99 or motor housing 101a via conduction is pumped through the pump head 108. Figure 4(b) shows an exploded view of a head assembly 100 of an alternative embodiment with end plate 101, a channel cover 102 and a pump head 108. The end plate 101 is adapted with a motor cooling channel(s) 104. The motor housing assembly 99 has the end plate 101. The pump head 108 is then attached on the cooling channel cover 102 to complete the assembly.

Figure 4(c) shows the perspective view of a head assembly of an alternative embodiment of the booster pump. The end plate 101 of motor housing assembly 99 has motor cooling channel(s) 104 and is continuously fed with fluid through the inlet 104a which thermally conducts away heat from the motor housing assembly 99 or motor housing 101a via conduction and continuously drains the thermally conducted fluid through the outlet 104b.

Therefore, the improved booster pump with motor cooling channel(s) removes heat as well as the orientation of pump head leads to an improved performance of said booster pump. The motor cooling channels on the end plate cools the motor housing assembly or motor housing of the improved booster pump and orientation of fluid booster chambers on the pump head helps in filling the fluid in each fluid booster chambers while horizontally mounted. The improved performance is defined as increase in open flow rate in the range of 10-11% and flow rate in the range of 45-46% when back pressure is applied to said improved booster pump.

Claims

CLAIMS We claim:

1. An improved booster pump with motor cooling channel(s) ( 104) comprising of: a head assembly (100) comprising of a head cap (103), a pump head (108) and a cooling channel cover (102); an end plate (101); and a motor housing assembly (99) comprising a motor housing (101a) assembled to said head assembly (100); wherein;

said end plate (101) is either inbuilt in said motor housing assembly (99) or assembled in front of the motor housing (101a); the head cap (103) is attached to the pump head (108) that is attached to the cooling channel cover (102) and said cooling channel cover (102) gets fitted into the end plate (101) of the motor housing assembly (99); said end plate (101) has motor cooling channel(s) (104) that remove heat from the motor housing assembly (99) or motor housing (101a); and said pump head (108) has an orientation of plurality of fluid booster chambers (113a, 113b, 113c) having two fluid booster chambers (113a, 113b) positioned parallel to mounting of said booster pump and one fluid booster chamber (113c) positioned below the fluid booster chambers (113a, 113b) to provide booster pump with improved performance.

2. The pump as claimed in claim 1, wherein, the head cap (103) has an inlet (111) and outlet (112) for fluid.

3. The pump as claimed in claim 1, wherein, the cooling channel cover (102) has an inlet (104a) and an outlet (104b) for fluid.

4. The pump as claimed in claim 1, wherein, the orientation allows the fluid to collect in each fluid booster chamber (113a, 113b, 113c) and booster pump to work in vertical and horizontal direction.

5. The pump as claimed in claim 1, wherein, the improved performance is defined as increase in open flow rate by 10-11% and flow rate by 45-46% when back pressure is applied to said booster pump while mounted horizontally.

6. An improved booster pump comprising of: a head assembly (100) comprising of a head cap (103), a pump head (108); an end plate (101); and a motor housing assembly (99) comprising a motor housing (101a) assembled to said head assembly (100); wherein;

said end plate (101) is either inbuilt in said motor housing assembly (99) or assembled in front of the motor housing (101a); the head cap (103) is attached to the pump head (108) that gets fitted into the end plate (101) of the motor housing assembly (99) or motor housing (101a); and said pump head (108) has an orientation of plurality of fluid booster chambers (113a, 113b, 113c) having two fluid booster chambers (113a, 113b) positioned parallel to mounting of said booster pump and one fluid booster chamber (113c) positioned below the fluid booster chambers (113a, 113b) to provide booster pump with improved performance.

7. The pump as claimed in claim 6, wherein, the head cap (103) has an inlet (111) and outlet (112) for fluid.

8. The pump as claimed in claim 6, wherein, the improved performance is defined as increase in open flow rate by 10-11% and flow rate by 45-46% when back pressure is applied to said booster pump while mounted horizontally.

9. The pump as claimed in claim 6, wherein, the orientation allows the fluid to collect in each fluid booster chambers (113a, 113b, 113c) through the inlet (111) and pumped out through the outlet (112) and allows booster pump to work in vertical and horizontal direction.

10. A booster pump with motor cooling channel(s) (104) comprising of: a head assembly (100) comprising of a head cap (103), a pump head (108), a cooling channel cover (102); an end plate (101); and a motor housing assembly (99) comprising a motor housing (101a) assembled to said head assembly (100);

wherein;

said end plate (101) is either inbuilt in said motor housing assembly (99) or assembled in front of the motor housing (101a); the head cap (103) is attached to the pump head (108) that is attached to the cooling channel cover (102) and said cooling channel cover (102) gets fitted into the end plate (101) of the motor housing assembly (99) or motor housing (101a); and said end plate (101) has motor cooling channel(s) (104) that remove heat from the motor housing assembly (99) or motor housing (101a).

11. The pump as claimed in claim 10, wherein, the head cap (103) has an inlet (111) and outlet (112) for fluid.

12. The pump as claimed in claim 10, wherein, the cooling channel cover (102) has an inlet (104a) and an outlet (104b) for fluid.

13. The pump as claimed in claim 10, wherein, the motor cooling channel(s) (104) are continuously fed with fluid through the inlet (104a) which thermally conducts away heat from the motor housing assembly (99) or motor housing (101a) via conduction and continuously drains the thermally conducted fluid through the outlet (104b).