Pump motor having sumbersible stator and rotor

Abstract: A brushless d.c. pump motor includes a pump housing (12) having an impeller chamber (14). An impeller (16) is disposed in the impeller chamber (14). A motor assembly is coupled to the pump housing. The motor assembly includes a stator assembly (32) defining an interior chamber (38). The stator assembly (32) includes a stator core (34) and windings (36). The windings (36) and at least a portion of the stator core (34) are in open communication with the interior chamber (38). A rotor assembly (42) is disposed in the interior chamber (38). A shaft (46) is provided on which the rotor assembly (42) and impeller (16) are mounted. The shaft (46) includes a hollow portion (47) in open communication with the interior chamber (38). Bearing structure (48,49,50) is operatively associated with the hollow portion (47) of the shaft for supporting the shaft (46) for rotational movement. An electronic control (60) unit is coupled to the motor assembly and has an upper surface (62) in communication with the interior chamber (38). Fluid flow path structure (64) is constructed and arranged to permit fluid to pass from a high pressure portion (20) of the impeller chamber (14) and enter the interior chamber (38) so that the rotor assembly (42), the windings (36), and the portion of the stator core (34) may be submerged in the fluid for cooling the same. Fluid may contact the upper surface (62) of the electronic control unit to cool the electronic control unit. Fluid may enter the hollow portion (47) of the shaft (46) to cool the bearing structure (48,49,50). Fluid return structure permits fluid in the interior chamber to return to a low pressure portion of the impeller chamber.

Description: FIELD OF THE INVENTION The present invention relates to a brushless electric motor. BACKGROUND OF THE INVENTION Water pump motors typically include a rotor assembly mounted in a rotor chamber and a stator assembly, having laminations and a winding set, operatively associated with the rotor assembly. The rotor assembly shares a bearing-supported shaft with an impeller of the pump. Water pump motors generally have some type of cooling to extend the operating capability thereof. In general, it is desirable to maintain the temperature of such devices below a predetermined limit in order to prevent deterioration of the device through thermal breakdown or distortion due to thermal expansion of elements of the device. In certain pump motors, the stator assembly and rotor assembly may be in fluid contact to cool the same, and the bearings may be in heat exchange relation with the fluid. Water pump motors for use in today's automobiles are electronically controlled and generally have an electronic control unit electrically coupled to the winding set of the motor. The electronic control unit generates heat that may limit the operating temperature of the pump motor. Thus, there is a need to provide cooling not only of the bearings, rotor assembly and stator assembly of the device, but also of the electronic control unit thereof. US 4,644,202 describes a brushless electric motor in which a small portion of fluid is leaker through a seal and acts to cool the motor. SUMMARY OF THE INVENTION An object of the present invention is to fulfill the need referred to above. In accordance with the present invention, there is provided a brushless electric motor comprising: a stator assembly defining an interior chamber, said stator assembly including a stator core and windings, said windings and at least a portion of said stator core being in open communication with said interior chamber, a rotor assembly in said interior chamber, a shaft on which said rotor assembly is mounted, said shaft including a hollow portion in open communication with said interior chamber, bearing structure operatively associated with the hollow portion of said shaft for supporting said shaft for rotational movement, an electronic control unit coupled to said stator assembly and having an upper surface in communication with said interior chamber, fluid flow path structure constructed and arranged to permit fluid to pass from an inlet in said stator assembly and enter said interior chamber so that said rotor assembly, said windings, and said portion of said stator core may be submerged in the fluid for cooling the same, and fluid may contact said upper surface of said electronic control unit to cool the electronic control unit, and fluid may enter said hollow portion of said shaft to cool said bearing structure, and fluid return structure permitting fluid in said interior chamber to pass out of said stator assembly. Other objects, features and characteristic of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawing, all of which form a part of this specification. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of a water pump motor embodying the present invention. DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS Referring to FIG. 1, a brushless d.c. water pump motor is shown generally indicated at 10, which embodies the principles of the present invention. The water pump motor 10 includes a pump housing 12 defining an impeller chamber 14. An impeller 16 is disposed in the impeller chamber 14. The pump housing and impeller may be of any conventional type having an exit 18 at an outer or high pressure portion 20 of the impeller chamber 14, and an inlet 22 at a low pressure portion 24 of the impeller chamber 14. A motor assembly, generally indicated at 26, is coupled to the pump housing 12 via bolting 30. The motor assembly 26 includes a stator assembly, generally indicated at 32, having the conventional laminations or stator core 34 and windings 36. The stator assembly 32 defines a generally cylindrical interior chamber 38 and a rotor assembly 42 is disposed in the interior chamber 38. As shown in the Figure, the windings 36 and a portion 44 of the laminations 34 or stator core are in open fluid communication with the interior chamber 38. The rotor assembly 42 has the conventional magnets 45 mounted on the outer peripheral portion thereof. A shaft 46 is provided on which the rotor assembly 42 and impeller 16 are mounted. The shaft 46 is hollow and thus fluidly communicates the interior chamber 38 with the impeller chamber 14 via passage 47 therethrough. The shaft 46 is mounted for rotation via bearing structure 48, including bearings 49, that is operatively associated with the shaft 46 for supporting the hollow shaft 46 for rotational movement. Bearings 49 are housed in a bearing housing, generally indicated at 50, which includes a boss portion 52, and a generally disk-shaped portion 54 which is coupled to the stator assembly 32. An electronic control unit 60 containing the circuitry to operate the water pump motor 10 is coupled to the motor assembly 26 (in particular, to the stator assembly 32) and has an upper surface 62 in communication with the interior chamber 38. Surface 62 may be part of a heat sink of the electronic control unit 60. A fluid flow path structure, generally indicated at 64, is provided to permit fluid to pass from the high pressure portion 20 of the impeller chamber 14 to an inlet 66 of the motor assembly 26 and enter the interior chamber 38 so that the rotor assembly 42, windings 36 and portion 44 of the stator core may be submerged in fluid and fluid may contact the upper surface 62 of the electronic control unit 60 to cool the electronic control unit. Further, the fluid may enter the hollow shaft 46 and be in heat transfer relation therewith to cool the bearing structure 48. In the embodiment of FIG. 1, the fluid flow path structure 64 includes a plurality of passages 70 through the stator assembly 32 and in particular through laminations 34 so as to be in fluid communication with interior chamber 38. As shown, passages 70 also communicate with the upper surface 62 of the electronic control unit 60. With reference to the arrows in FIG. 1, fluid may flow from the high pressure portion 20 of the impeller chamber 14 through the inlet 66 of the motor assembly 26 and through the passages 70 in the stator assembly 32 and into the interior chamber 38. As a result, the rotor assembly 40, windings 36 and portion 44 of the stator core 34 are submerged in the fluid and fluid contacts the upper surface 62 of the electronic control unit 60 to cool the same. The laminations 34 are also cooled by the fluid flowing through passages 70 in the stator assembly 32. Fluid may pass through the passage 47 (fluid return structure) in the hollow shaft 46 and thus return fluid to the low pressure portion 24 of the impeller chamber 14. As shown in the Figure, an o-ring seal 72 provides a seal between the pump housing 12 and the motor assembly 26 and a o-ring seal 74 provides a seal between the stator assembly 32 and the electronic control unit 60. Thus, it can be seen that the rotor assembly, laminations, windings, bearing structure and the electronic control unit are cooled effectively by the circulating fluid. It has thus been seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.

Claims: A brushless electric motor comprising: a stator assembly (32) defining an interior chamber (38), said stator assembly (32) including a stator core (34) and windings (36), said windings (36) and at least a portion of said stator core (34) being in open communication with said interior chamber (38), a rotor assembly (42) in said interior chamber (38), a shaft (46) on which said rotor assembly (42) is mounted, said shaft (46) including a hollow portion in open communication with said interior chamber (38), bearing structure (48) operatively associated with the hollow portion of said shaft (46) for supporting said shaft for rotational movement, an electronic control unit (60) coupled to said stator assembly (32) and having an upper surface in communication with said interior chamber (38), fluid flow path structure (64) constructed and arranged to permit fluid to pass from an inlet (66) in said stator assembly (32) and enter said interior chamber (38) so that said rotor assembly (42), said windings (36), and said portion of said stator core may be submerged in the fluid for cooling the same, and fluid may contact said upper surface of said electronic control unit (60) to cool the electronic control unit (60), and fluid may enter said hollow portion of said shaft (46) to cool said bearing structure (48), and fluid return structure (47) permitting fluid in said interior chamber (38) to pass out of said stator assembly (32). The brushless motor according to claim 1, further comprising a pump housing (12) having an impeller chamber (14), an impeller (16) in said impeller chamber (14), wherein said hollow portion of said shaft (46) is in open communication with a low pressure portion of said impeller chamber (14) thereby defining said fluid return structure (47). The brushless motor according to claim 2, wherein said flow path structure (44) includes at least one passage through said stator assembly (32) that is in communication with said upper surface of said electronic control unit (60) and with said interior chamber (38), whereby fluid may flow from a high pressure portion of the impeller chamber (14) and through said passage into contact with the upper surface of said electronic control unit (60), and into said interior chamber (38) and fluid may pass through said hollow portion of said shaft (46) and to said low pressure portion of said impeller chamber (14). The brushless motor according to claim 3, wherein said at least one passage through said stator assembly (32) passes through laminations (34) of said stator assembly (32). The brushless motor according to claim 1, in combination with a pump, said pump having a pump housing coupled to said stator assembly (32) and defining an impeller chamber (14), an impeller (16) being disposed in said impeller chamber (14), said impeller (16) being coupled to said shaft (46), a high pressure portion of said impeller chamber (14) being in fluid communication with said fluid inlet and a low pressure portion of said impeller chamber (14) being in fluid communication with said fluid return structure (47). The brushless pump motor according to claim 1, wherein said interior chamber (38) is generally cylindrical. The brushless motor according to claim 2, further including first and second o-ring seals, said first o-ring seal sealing a connection of said stator assembly (32) and said housing (12) and said second o-ring seal sealing a connection of said stator assembly (32) and said electronic control unit (60).

Inventors: HORSKI MAREK, KERSHAW PETER, MUSZYNSKI JERZY, HORSKI, MAREK, KERSHAW, PETER, MUSZYNSKI, JERZY
Applicants: SIEMENS VDO AUTOMOTIVE INC, SIEMENS VDO AUTOMOTIVE INC.
Application year: 1998
Main classification: F04D13
IPC codes: F04D13, F04D29, H02K9, H02K5, H02K7, H02K11