A MOTOR-PUMP ASSEMBLY

Abstract: A motor-pump assembly has an air-lock sealing arrangement located between the motor and pump to prevent contamination of the motor by the fluid being pumped and provide a low friction seal therebetween. The motor-pump assembly (2) has a housing (8), motor chamber (31), motor (24), shaft (73), pump chamber (90) and pump (112). An air-lock chamber (70) is located between the motor chamber (31) and the pump chamber (90) and serves to prevent the fluid being pumped from ingressing into the motor chamber (31). Fluid retaining means (71) containing a seal fluid is provided in the air-lock chamber (70) and is connected to the shaft (73) for rotation therewith. The seal fluid acts as a low friction seal between a bush (5), which surrounds the shaft (73) and extends downwardly from the motor chamber (31), and the air-lock chamber (70).

Description: "A MOTOR-PUMP ASSEMBLY" The present invention relates to a motor-pump assembly having an airlock sealing arrangement located intermediate the pump portion and the motor portion. More particularly, the present invention relates to a motor-pump assembly for_ use in swimming pool installations where safety is of paramount importance. A swimming pool filter installation incorporating a motor-pump assembly forms the subject of my co-pending application No. PF 3936, and the motor-pump assembly of the present invention finds particular application in such a filtering installation as described. Pumps previously used in domestic swimming pool installations have suffered from a number of problems. One such problem has been to isolate the motor portion from the pump portion to adequately prevent contamination of the motor components, including the electrical control circuitry, by the water flowing through the pump portion. Another such problem, has been to provide a sealing means which is long lasting and hard wearing between the pump portion .and the motor portion, particularly around the output shaft of the motor portion. It is an aim of the present invention to provide a pump which at least alleviates some of the problems inherent in prior pumps. According to the present invention there is provided a motor-pump assembly comprising a motor chamber for housing a motor and a pump chamber for housing a pump means for pumping a first fluid through the pump chamber wherein an output shaft of the motor extends from the motor chamber into the pump chamber for connection to the pump means, the motor chamber and pump chamber being housed in a body, characterised in that the output shaft extends through a gas-lock chamber which is located between the motor chamber and the pump chamber to prevent the first fluid from ingressing into the motor chamber, said gas-lock chamber comprising a second fluid retaining means for retaining a second fluid which provides a fluid seal between the motor chamber and the gas-lock chamber. Preferably, the second fluid provides both a sealing means against the first fluid ingressing into the motor chamber, and lubrication for a bearing means which allows relative rotation of second the output shaft. Preferably, an impeller having a plurality of blades is located in the pump chamber to provide a directing means to hinder the second fluid from entering the gas-lock chamber. Preferably, there is a convoluted pathway connecting the pump chamber and the gas-lock chamber so that the first fluid is hindered from entering the gas-lock chamber. OMPI Preferably, the motor-pump assembly has an air-lock arrangement comprising a first sealing means which is a fluid arranged to prevent air escaping from the air-lock chamber and a second sealing means which is a second fluid, said first fluid being different from said second fluid. Preferably, the motor-pump assembly has a first air-tight chamber formed with substantially rigid sealing means, a second chamber substantially filled with a fluid, a third air-lock chamber formed with " both rigid sealing means and fluid sealing means, a fourth chamber containing at least partially a second fluid, arranged so that the first fluid and second fluid are prevented from intermixing. The present invention will be described by way of example in which: FIGURE 1 is a side elevation view of one embodiment of the present invention with a fragmentary portion of the view showing the internal structure of an outlet port; and FIGURE 2 is a cross-section view of the motor-pump assembly shown in Figure 1. In Figure 1 there is shown a submersible motor-pump assembly generally denoted as 2, comprising a lid 4 having a handle 6, a cylindrical housing 8 to protect the internal components of the motor and some of the pump mechanicals, a plurality of inlet ports 10 circumferentially located around the assembly between the housing and a base 12 having an internally located outlet port 14. The assembly finds particular application as part of a filter installation, particularly in filter units of swimming pools by being rotatable with respect to the remainder of the installation (not shown) which is fixed in position having external plumbing fittings connected to it. Different operating modes of the installation may be effected by rotating the assembly within the installation. Handle 6 is provided to allow for easy insertion and removal of the assembly into and from the filter installation such as during servicing of the assembly, and also to provide a means of rotating the assembly in order to alter the operation of the installation from one working mode to another say for example, from a filter mode to a backwash mode. Lid 4 is releasably secured to the top of the housing by means of suitable fastening means 16 passing * through flanges 18 and 32 and through flanges 20 and 22 in order to gain access to the internal components (not shown) of the motor 24 such as the control circuitry. A thermal overload mechanism (net shown) which is part of the control circuitry, operates to prevent damage to the assembly whenever an adverse operating condition arises during use of the assembly. The thermal overload mechanism which is located inside an air bell cavity 22 in order to prevent water from flooding the overload mechanism which comprises a reset button, a connecting rod and a lever arranged so that movement of the button is transmitted by the push rod to the lever. After the thermal overload mechanism has been tripped, the reset button may be pushed to reset the mechanism to allow continued operation of the assembly. A seal (not shown) is located between the lid 4 and flange 32 to ensure that the air bell cavity 5 is air tight, and a mercury switch (not shown) is included in the control circuitry so that the assembly may only be used in an upright position. The top of housing 8 is closed by a top cover plate 30 which comprises a circumferential flange 32 integrally formed to a downwardly directed wall section 34 so that to top circumference of housing 8 abuts flange 32 and the wall section snugly engages the bore of the housing. An O-ring 36 is located in wall, section 34 to provide a seal between the cover plate and the housing. A conducting rod 38 is moulded into the top cover plate to extend through it in order to provide electrical connection from one side to the other of the electrical insulating top cover plate. The rod is moulded in the top cover plate so that air may not escape from the cavity 5 between the rod and the top cover plate. A circular intermediate sealing plate 44 which comprises an upwardly-facing sealing surface 46, a centrally located, downwardly extending, elongate bush 50, and a circumferentially located downwardly extending side skirt 48, is transversely located inside the housing. The chamber defined within housing 8 between plates 30 and 44 forms a motor chamber 31 in which is located the electric motor 24. The motor comprises a cylindrical metal rotor 33 connected to output shaft 73 and a starter winding 35 located circumferentially around the rotor. Bearings 37, 39 are located above and below the rotor. A bypass duct 51 is formed in intermediate sealing plate 44 extending from the motor chamber 31 into the interior of elongate bush 50 so that there is fluid communication between the interior of the bush and the motor chamber. Sealing surface 46 has a recessed cavity 42 in which roller bearing 39 is located to support the output shaft 73 of the motor which extends downwardly from the motor through sealing plate 44 in order to rotate freely within bush 50 which is a tube surrounding the output shaft and spaced from the output shaft by a * spacer 78. The output shaft 73 extends through an air-lock chamber 70 (to be described in more detail later) and has its end connected to an impeller 112 so that when the output shaft rotates, the impeller spins. An O-ring 52 is located in skirt 48 to provide a seal between- the sealing plate and the housing. A circular base plate 60 which comprises an upwardly extending side skirt 62, a downwardly sloping, inwardly directed, annular section 64 and a circumferential, outwardly extending flange 66, is located within the housing at its lower end coaxially with and immediately below the intermediate sealing plate 44 such that the ends of the respective side skirts 48, 62 abut each other. The intermediate sealing plate 44 and the base plate 60 are arranged such that an air-lock chamber 70 is formed by the outside surface of the elongate bush 50, the lower surface of the intermediate sealing plate 44, the inside surfaces of the respective side skirts 48, 62 and the upper surface of the annular section 64. An O-ring 63 is provided in skirt 62 to provide a seal CMPI between the base plate and the bore of the housing. There is a gap between the inner rim 68 of the annular section and free end 72 of the downwardly extending bush 50 so that the air-lock chamber is not completely closed. A base assembly 12, comprising a circumferential, outwardly extending flange 22, a downwardly extending base portion 82, and inwardly and downwardly sloping annular surface 84, is located coaxially with and immediately beneath the base plate 60. A plurality of inlet ports 10 are circumferentially formed around motor-pump assembly 2 by equispaced bosses 88 which maintain flange 22 in spaced apart relationship from flange 66. Bosses 88 are formed by a first part 87 downwardly extending from flange 66 aligned with and resting on top of a second part 89 which extends upwardly from flange 22. Parts 87 and 89 are each integrally moulded to respective flanges 66 and 22. A circular impeller cavity 86 which is formed in the base portion immediately below annular section 84, has the outlet port 14 downwardly extending from it on one side through base portion 82. A pump chamber 90, located between base plate 60 and base assembly 12, is formed by an annular concavity in the lower surface of annular section 64, the bosses 88, and the sloping upper surface 84 of base portion 82. Water admitted through inlet ports 10 is pumped around pump chamber 90 and discharged through outlet port 14. The free end 72 of bush 50 is located inside of an annularly shaped oil well 77. An annular oil retaining CMPI cup 71, having arcuate sides inwardly directed at the top and bottom, is integrally formed at its bottom with a connecting piece 75 which is fixed to the output shaft. Since oil retaining cut 71 is fixed to shaft 73, when shaft 73 rotates the cup spins around in chamber 70 and bush 50 remains stationary. Oil is provided in oil well 77 to lubricate the relative rotation of the connecting piece and the bush, and to provide a seal between the air-lock chamber 70 and the motor chamber 31. Thus, air-lock chamber 70 comprises two parts, the inner part which is located inside the oil retaining cup and an outer part which is located outside the oil retaining cup. Any oil flung radially outwardly from the oil well as the shaft spins is prevented from escaping from the inner part of air-lock chamber by the bow-shaped side wall 74 of the oil retaining cup acting as a collector and drainage surface for the oil. Impeller 112 which is fixedly connected to the free end of the output shaft 73 for rotation with the output shaft comprises an impeller shaft 100 extending from the output shaft 73 to the blades of the impeller 104, a deflector ring 106 located towards the end of the impeller shaft connected to the ouput shaft and impeller blades 104. Deflector ring 105 is a solid disc radially extending from the impeller shaft inclined upwardly so as to be substantially parallel to annular section 64 so as to deflect water being pumped around pump chamber 90 away frc entering convoluted pathway 106 formed by the deflector ring, the impeller shaft, annular section 64 and connecting piece 75. Impeller blades 104 comprise a solid lower disc 108 connected to the end of impeller shaft 100 and an upper annular ring 110 spaced from and arranged substantially parallel to lower disc 108. Radially curved vanes 114, extend between the two parallel discs 108, 110 towards their outer circumference. It is to be noted that impeller blades and vanes 108, 110, 114 may be selected from conventional impeller blades. In operation, as the output shaft rotates the impeller spins to pump water from a swimming pool into the pump chamber via the inlet ports and then around the.pump chamber to the impeller cavity to be discharged through outlet port 10. Since the deflector ring is so shaped to retain the water substantially inside the pump chamber very little, if any, water is allowed to pass into the convoluted pathway 106 between the pump chamber and the air-lock chamber. Any water that may find its way into the pathway is retained on the top surface of the impeller and is eventually flung outwardly into the pump chamber and in to the impeller cavity for discharge by the spinning action of the impeller. The oil in the oil well may be flung against the inside surface of the wall of the oil retaining cup but is prevented from escaping into the air-lock chamber on the outside of the oil retaining cup by the described arrangement, including the collector and drainage surface of the oil retaining cup. Motor chamber 31 is completely filled with oil and is air-tightly sealed to housing 8, so that oil is prevented from flowing out of motor chamber 31, via O PI both annular space 78 between bush 50 and the output shaft 73 into the oil well and into the air-lock chamber since no air is able to ingress into the motor chamber to fill the space vacated by the displaced oil, i.e. the sealed motor chamber 31 acts as an air-bell to prevent oil escaping from it. Similarly, air is prevented from escaping from the air-lock chamber since this chamber is sealed at the top by the oil and at the bottom by the water in the pump chamber. As no air is able to escape from the air-lock chamber, water is * not able to ingress into the air-lock chamber, except perhaps to slightly compress the air in the air-lock chamber. However, in the event that some water may ingress into the air-lock chamber, the outer ' surface of the oil retaining cup prevents-the water from mixing with the oil in the oil well. One advantage of the described arrangement is that a low voltage motor may be used in the assembly since the oil in the oil well provides a low-friction seal between the motor chamber and the air-lock chamber. Such low-friction seals do not require high torque from motors used in conjunction with them. In previously available motor-pump assemblies, the seal between the motor portion and the pump portion has been a high-friction ceramic type which requires a motor developing high torque to initially overcome the inherent internal friction of the seal. Such high-torque motors require high voltages which are undesirable in motors used in swimming pools as described. One such modification is to integrally form the top cover plate and the housing as a one-piece moulding in plastics material so that a separate sealing between the top cover plate and the housing may be dispensed with. A further modification is to form the impeller with 2 blades or more. Although the present invention has been described with particular reference to a motor-pump assembly for use in a swimming pool filter installation, it is to be noted that the assembly may be used in any situation that requires a motor connected to a pump having a low friction sealing means around the motor output shaft that can prevent ingress of the fluid being pumped into the motor chamber. _ O PI

Claims: CLAIMS : 1. A motor-pump assembly (2) comprising a motor chamber (31) for housing a motor (24) and a pump chamber (90) for housing a pump means (112) for pumping a first fluid through the pump chamber wherein an output shaft (73) of the motor extends from the motor chamber into the pump chamber for connection to the pump means, the motor chamber and pump chamber being housed in a body (8) , characterised in that the output shaft extends through a gas-lock chamber (70) which is located between the motor chamber and the pump chamber to prevent the first fluid from ingressing into the motor chamber, said gas-lock chamber comprising a second fluid retaining means (71) for retaining a second fluid which provides a fluid seal between the motor chamber and the gas-lock chamber. 2. A motor-pump assembly according to claim 1 characterised in that the second fluid retaining means {71} is connected to the output shaft for rotation with the output shaft relative to a tubular element (50) which is stationary with respect to the body and surrounds the output shaft, said second fluid retaining means defining a fluid well around a free end of the tubular element. 3. A motor-pump assembly according to claim 2 characterised in that the second fluid retaining means includes a fluid collector (74) which has a drainage surface axranged such that the second fluid when radially thrown out from the v/ell in use is returned to the well. 4. A motor-pump assembly according to claim 3 characterised in that the fluid collector is substantially bowl shaped having a central axis of rotation and an opening through which the output shaft passes, said axis of rotation being aligned with the motor output shaft and the side walls of the collector are convex. 5. A motor-pump assembly according to claim 4 characterised in that the fluid collector has a lip portion at said opening which assists- in returning second fluid to the well. 6. A motor-pump assembly according to claim 5 characterised in that there is an opening defined between the tubular element and the body in which the second fluid retaining means may rotate. 7. A motor-pump assembly according to claim 6 characterised in that a portion of the convex side wall is located adjacent to part of the defining walls of the gas-lock chamber. 8. A motor-pump assembly according to claim 5, 6 or 7 characterised in that an impeller (112) is connected to the output shaft adjacent the second fluid retaining means for rotation with the output shaft, the impeller " being arranged to pump the first fluid in use. 9. A motor-pump assembly according to claim 8 characterised in that the impeller includes a deflector means to deflect the first fluid away from the gas-lock chamber as the pump means pumps the first fluid through the pump chamber. 10. A motor-pump assembly according to claim 9 characterised in that the second fluid retaining means, the body and the deflector means define a convoluted pathway between the gas-lock chamber and the pump chamber to hinder ingress of the first fluid into the gas-lock chamber. 11. A motor-pump assembly according to claim 10 characterised in that the pump.chamber includes an impeller cavity (86) , in which blades (104) of the impeller rotate to pump the second fluid into an outlet means (14) , and an inlet chamber (90) in which the deflector means is located. 12. A motor-pump assembly according to claim 11 characterised in that there are a plurality of inlet means (10) located circumferentially around the body, said inlet means in fluid communication with the inlet chamber such that the first fluid is admitted in generally radially flowing streams and those parts of the streams which are directed towards said convoluted pathway are intercepted by the deflector means to be deflected away from the convoluted pathway by the deflector means towards the impeller cavity for discharge through the outlet means. 13. A motor-pump assembly according to any one of the preceding claims characterised in that the second fluid is oil. 14. A motor-pump assembly according to claim 13 characterised in that there is at one duct extending from the motor chamber to the interior of the tubular element. 15. A motor-pump assembly according to claim 14 characterised in that the motor chamber contains oil which may pass through the duct or ducts into the oil well. 16. A motor-pump assembly substantially as hereinbefore described with reference to the accompany drawings. _ CMP

Inventors: RICE JOHN TREVOR, RICE, JOHN, TREVOR
Applicants: RICE JOHN TREVOR, RICE, JOHN, TREVOR
Application year: 1982
Main classification: F04D13
IPC codes: F04D13, F04D29