GB2357192A

GB2357192A - Heat transfer between rotor and end cap

Info

Publication number: GB2357192A
Application number: GB9929099A
Authority: GB
Inventors: Luc Jouanjan
Original assignee: Delphi Technologies Inc
Current assignee: Delphi Technologies Inc
Priority date: 1999-12-10
Filing date: 1999-12-10
Publication date: 2001-06-13
Also published as: GB9929099D0

Abstract

An electric motor or generator 10 comprising a housing 22 substantially surrounding the stator and the rotor and having an end wall 24 adjacent the rotor, in which wall is formed an annular slot 32, the shaft mounted fan 42 having a planar portion 44 with an outer edge 48 and a number of fan blades 46 extending from the planar portion adjacent the outer edge into the annular slot in the end wall to improves heat transfer from the rotor to the end wall of the housing. The base of the slot may be castellated and housing may have liquid coolant channels 50.

Description

2357192 ELECTRIC MOTOR OR GENERATOR

Technical Field

The present invention relates to an electric motor or generator.

Background of the Invention

An electric motor or generator comprises a stator with a stator winding, a rotor with a rotor winding mounted on a rotatable shaft inside the stator, and a housing for supporting and covering the stator, the rotor, and the shaft. Air gaps are formed inside the housing between the rotor, the stator, and the housing. Heat generated by the rotor is transferred from the rotor through the air to the housing. It has been found that the air between the rotor and an end wall of the housing remains substantially static, and laminated layers of air are formed, the laminations having different temperature levels.

It is believed that this leads to an inefficient transfer of heat from the rotor to the end wall of the housing.

Summary of the Invention

It is an object of the present invention to overcome the above mentioned problem.

An electric motor or generator in accordance with the present invention comprises a shaft rotatable about its longitudinal axis; an annular stator positioned around the shaft; a rotor mounted on the shaft inside the stator; a housing substantially surrounding the stator and the rotor and having an end wall, the shaft extending into an aperture in the end wall; an annular slot formed in the end wall adjacent the rotor; a fan secured to the shaft between the rotor and the end wall, the fan having a planar portion with an outer edge, and a number of fan blades extending from the planar portion adjacent the outer edge into the annular slot in the end wall.

2 The fan blades pass round the annular slot as the shaft rotates, creating turbulence in the air within the slot. The movement of the air assists in the transfer of heat from the rotor to the end wall of the housing.

Brief Description of the Drawinas

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: - Figure I is a cross-sectional view of an electric motor or generator in accordance with the present invention; Figure 2 is an end view of the end wall and fan of the electric motor or generator of Figure 1; Figure 3 is a cross-sectional view on the line 111-III of Figure 2; Figure 4 is a cross-sectional view on the line IV-IV of Figure 2; and Figure 5 is a perspective view of the fan of the electric motor or generator of Figure 1.

Description of the Preferred Embodiment

Referring to the drawings, the electric motor or generator 10 in accordance with the present invention has particular application in a motor vehicle, and includes a stator 12 with a stator winding 14; a rotor 16 with a rotor winding 18; and a shaft 20 rotatable about its longitudinal axis A. The stator 12 is substantially annular and the rotor 16 is positioned inside the stator. The rotor 16 is secured to the shaft 20 such that the rotor can rotate about the axis A relative to the stator 12. The stator 12 and rotor 16 are positioned inside a housing 22 having an end wall 24. The shaft 20 is rotatably mounted in a bearing 26 located in an aperture 28 in the end wall 24 of the housing 22.

The internal surface 30 of the end wall 24 has an annular slot 32 formed therein around the aperture 28 and centred on the axis A. The surface 34 of the slot 32 has a castellated form with a series of U- shaped steps 3 36 formed therein. The shape and size of the steps 36 are substantially identical and define regions 38 of reduced cross-sectional area within the slot 32 between regions 40 (between the steps 36) where the cross-sectional area is notreduced.

A fan 42 is secured to the shaft 20 between the rotor 16 and the end wall 24 of the housing 22. The fan 42 comprises an annular planar portion 44, and a number of fan blades 46 extending away from the planar portion adjacent the outer edge 48 thereof. The fan blades 46 are substantially flat and planar, and extend in both a radial direction and an axial direction.

The planar portion 44 of the fan 42 is secured to the shaft 20 and is positioned adjacent the rotor 16. The fan blades 46 protrude into the slot 32 in the end wall 24. Each fan blade 46 is shaped and sized to pass through the regions 38 of reduced cross-sectional area in the slot 32, but provide a close sliding fit with the steps 36.

On rotation of the shaft 20 and the rotor 16, the fan 42 also rotates such that the fan blades 46 move around the slot 32. The fan blades 46 pass alternately between the regions 38 and 40 of the slot 32 creating turbulence in the air in the slot. Because of the regions 38,40 formed in the slot 32, the air is effectively forced to rotate around the fan blades 46 in each of the larger regions 40. The movement of the air assists in the transfer of heat from the rotor 16 through the air to the end wall 24 of the housing 22 and prevents the formation of laminations of air having different temperature levels. This arrangement improves the heat transfer from the rotor 16 to the end wall 24.

In certain circumstances, the steps 36 in the slot 32 may be omitted, and/or replaced by other means for assisting in the generation of turbulence in the air as the fan blades 46 rotate in the slot. The housing 22 may include one or more channels 50 for the passage of cooling fluid through the housing.

4

Claims

1. An electric motor or generator (10) comprising a shaft (20) rotatable about its longitudinal axis (A); an annular stator (12) positioned around the shaft; a rotor (16) mounted on the shaft inside the stator; a housing (22) substantially surrounding the stator and the rotor and having an end wall (24), the shaft extending into an aperture (28) in the end wall; an annular slot (32) formed in the end wall adjacent the rotor; a fan (42) secured to the shaft between the rotor and the end wall, the fan having a planar portion (44) with an outer edge (48), and a number of fan blades (46) extending from the planar portion adjacent the outer edge into the annular slot in the end wall.

2. An electric motor or generator as claimed in Claim 1, wherein the annular slot has a surface with a castellated form defined by a:

number of substantially U-shaped steps (36), the steps formed regions (38) of reduced cross-sectional area in the slot.

3. An electric motor or generator as claimed in Claim 2, wherein the regions of reduced cross-sectional area in the slot are shaped and sized relative to the fan blades to allow the fan blades to pass with a close sliding fit.

4. An electric motor or generator as claimed in any one of Claims I to 3, wherein the fan blades are substantially flat and planar and extend in an axial direction and a radial direction.

5. An electric motor or generator as claimed in any one of Claims 1 to 4, wherein the housing has one more channels therein for the passage of cooling fluid.

6. An electric motor or generator substantially as herein described with reference to, and as shown in, the accompanying drawings.