ELECTRIC MOTOR WITH HEAT DISSIPATION FOR THE MOTOR SHAFT BEARING

Abstract

The invention relates to an electric motor with a motor housing (2) which has a shaft section for receiving a motor shaft (4) and a motor section for receiving motor electronics (5) and motor windings (6), wherein the shaft section and the motor section are separated from each other in a sealed manner by a separating pot (7) arranged in the motor housing (2), wherein, in the separating pot (7), a metal ball bearing pot (8) is arranged, in which a ball bearing (9) is fixed, and wherein the ball bearing pot (8) lies indirectly against a motor housing section which is connected to the outer surroundings, via the separating pot (7), such that the motor housing functions as a cooling body, and heat generated by the ball bearing (9) during operation is dissipated onto the motor housing and the outer surroundings via the ball bearing pot (8) and the separating pot (7).

Claims

1. An electric motor with a motor housing (2) which has a shaft section for receiving a motor shaft (4) and a motor section for receiving motor electronics (5) and motor windings (6), wherein the shaft section and the motor section are separated from each other in a sealed manner by a separating pot (7) arranged in the motor housing (2), wherein, in the separating pot (7), a metal ball bearing pot (8) is arranged, in which a ball bearing (9) is fixed, and wherein the ball bearing pot (8) lies indirectly against a motor housing section which is connected to the outer surroundings, via the separating pot (7), such that the motor housing functions as a cooling body and heat generated by the ball bearing (9) during operation is dissipated onto the motor housing and the outer surroundings via the ball bearing pot (8) and the separating pot (7).

2. The electric motor according to claim 1, characterized in that the separating pot (7) is formed as a single piece through the motor housing (2) around a rotation axis of the motor shaft (4).

3. The electric motor according to claim 1 or 2, characterized in that the separating pot (7) and the ball bearing pot (8) are designed to be of identical shape in the section of the separating pot (7) in which the ball bearing pot (8) is arranged.

4. The electric motor according to any one of the preceding claims, characterized in that, between the separating pot (7) and the motor housing section (2) which is indirectly connected to the ball bearing pot (8) via the separating pot (7), a heat sink paste (10) is provided.

5. The electric motor according to any one of the preceding claims, characterized in that the motor housing has a detachable housing cover (3) which can be put on an axial side of the remainder of the motor housing (2) and which forms the section of the motor housing which is indirectly connected to the ball bearing pot (8) via the separating pot (7).

6. The electric motor according to the preceding claim, characterized in that the housing cover (3) has a cooling element (11) protruding axially in the direction of the ball bearing pot (8), which locally increases a surface for connection to the ball bearing pot (8) indirectly via the separating pot (7).

7. The electric motor according to the preceding claim, characterized in that the cooling element (11) is designed to be of cylindrical or conical shape with an axial surface for connection to an axial outer wall surface of the separating pot (7).

8. The electric motor according to any one of the preceding claims, characterized in that the ball bearing pot (8) forms a ball bearing seat into which the ball bearing (9) is pressed or inserted.

9. The electric motor according to any one of the preceding claims, characterized in that the ball bearing pot (8) has a free space (13) between the ball bearing (9) and the section of the motor housing (2) which is connected to the outer surroundings.

10. The electric motor according to any one of the preceding claims 5 to 9, characterized in that the separating pot (7) extends axially through the motor housing (2) up to the housing cover (3).

11. The electric motor according to any one of the preceding claims, characterized in that the motor housing (2) and the separating pot (7) are made of plastic, and the metal ball bearing pot (8) is directly overmolded with the plastic.

12. The electric motor according to any one of the preceding claims, characterized in that the motor windings (6) enclose the separating pot (7) in circumferential direction and are arranged axially spaced from the ball bearing (9).

13. The electric motor according to any one of the preceding claims 5 to 12, characterized in that the motor electronics (5) is arranged on a circuit board (14) which has a central opening (15), and in that the cooling element (11) protruding from the housing cover (3) extends through the central opening (15).

14. The electric motor according to any one of the preceding claims 5 to 12, characterized in that the motor electronics is arranged on a circuit board which has a central opening, and in that the separating pot (7) extends through the central opening.

Description

[0020] Other advantageous developments of the invention are characterized in the dependent claims and represented in further detail together with the description of the preferred embodiment of the invention in reference to the figures. In the drawings:

[0021] FIG. 1 shows a lateral cross-sectional view through an electric motor of an embodiment example;

[0022] FIG. 2 shows a detail view from FIG. 1.

[0023] In FIGS. 1 and 2, an embodiment example of an inventive electric motor 1 is represented in a lateral cross-sectional view and a detail view, respectively.

[0024] The electric motor 1 comprises the single-piece motor housing 2 with the housing cover 3 which can be axially fixed in a detachable manner on the motor housing 2 and which, in the fixed state, forms a part of the motor housing. On the side axially facing the housing cover 3, the motor housing 2 forms, as a single piece, the separating pot 7 extending into the interior of the motor housing 2. Between the inner wall of the motor housing 2 and the outer shell of the separating pot 7, the motor section is located, in which the motor windings 6 and the motor electronics 5 fixed on the circuit board 14 are received. Sealingly delimited via the separating pot 7, the shaft section, in which the motor shaft 4 extends along the rotation axis thereof, is located within the separating pot 7. The separating pot 7 extends in axial direction substantially through the entire motor housing 2 up to the housing cover 3.

[0025] In the deepest section of separating pot 7, when viewed in axial direction, the ball bearing pot 8 made of a heat conducting material, in particular metal, is arranged. The motor housing 2 with the separating pot 7 is injection molded with plastic around the ball bearing pot 8 in the injection molding process, so that the separating pot 7 and the ball bearing pot 8 have the same shape or inner and outer contours and directly adjoin one another. The ball bearing pot 8 determines the bearing seat for the pressed-in ball bearing 9 in which the motor shaft 4 is mounted. Between the ball bearing 9 and the axial inner wall surface of the separating pot 7, the free space 13 is formed, into which the motor shaft 4 extends with by means of its free end.

[0026] Around the rotation axis, on the housing cover 3, designed in such a manner as to form a single piece, is a cooling element 11 in the form of a cylinder made of solid material, protruding axially in the direction of the ball bearing pot 8. A layer of the heat sink paste 10 is provided axially between the cooling element 11 and the axial outer wall surface of the separating pot 7.

[0027] The heat dissipation of the heat generated during operation by the ball bearing 9 occurs from the ball bearing 9 onto the ball bearing pot 8, further onto the separating pot 7 and in axial direction via the heat sink paste 10 onto the cooling element 11 of the housing cover 3 of the motor housing 2. From the housing cover 3, the heat is dissipated further into the outer surroundings. The motor housing and in particular the housing cover 3 thereof therefore function as cooling body. In an alternative embodiment, not shown, the heat sink paste 10 is dispensed with and the cooling element 11 is in direct contact with the separating pot 7.

[0028] The separating pot 7 is hollow cylindrical and subdivided into three axial sections each with different inner diameters. In the region of the smallest diameter, the free space 13 is arranged, in the central region, the bearing seat with the ball bearing 9 is arranged, and in the region of the largest inner diameter, the motor windings 6 are arranged radially around the separating pot 7. The ball bearing 9 thus has no overlap with respect to the motor windings 5, when viewed in axial direction.

[0029] The circuit board 14 determines, around the rotation axis of the motor shaft 4, the central opening 15, through which, in axial direction, the cooling element 11 axially protruding from the housing cover 3 extends through to the separating pot 7. In an alternative variant, not represented, instead of the cooling element 11, the region of smallest diameter of the separating pot 7 can extend through the opening 15, so that the contact between separating pot 7 and cooling element 11 occurs axially above the circuit board 14. It can also be provided to design the housing cover 3 without a cooling element 11 and to move the separating pot 7 directly or via the heat sink paste 10 against the axial inner wall of the housing cover 3.