WO2017114555A1

WO2017114555A1 - Electric motor with improved heat dissipation and assemblage

Info

Publication number: WO2017114555A1
Application number: PCT/EP2015/081320
Authority: WO
Inventors: Nezih Gokhan OZCELIK; Caglar ACAR; Evren SOYDAN; Erdem COSKUN; Emre HAS; Ahmet CETINER; Cem DOGAN
Original assignee: Arcelik Anonim Sirketi
Priority date: 2015-12-29
Filing date: 2015-12-29
Publication date: 2017-07-06
Also published as: TR201617786A2

Abstract

The present invention relates to an electric motor (1) comprising an outer stator (2) which includes a core (3) and coils (4) which are disposed onto the core (3), a shaft, an inner rotor which is disposed around the shaft, a casing (5) which is adapted to enclose the circumferential surface of the outer stator (2). In the electric motor (1) of the present invention the casing (5) includes a first half casing (6) which is adapted to receive and contact the first circumferential half of the core (3) and a second half casing (7) which is adapted to receive and contact the second circumferential half of the core (3).

Description

ELECTRIC MOTOR WITH IMPROVED HEAT DISSIPATION AND ASSEMBLAGE

The present invention relates to the casing of the electric motor.

Electric motors are commonly known in the art. Electric motors can be used both in industrial applications and in domestic applications. Figure 1 to 5 show an electric motor (1’) which is known from the prior art. The electric motor (1’) comprises an outer stator (2’) which includes a core (3’) and coils (4’) which are disposed onto the core (3’), a shaft (not shown); an inner rotor (not shown) which is disposed around the shaft, a casing (5’) which encloses the circumferential surface of the outer stator (2’), a front cap (not shown) and a rear cap (not shown) which cover the front aperture and the rear aperture of the casing (5’) respectively. The front cap, the rear cap and the casing (5’) protect the electric motor (1’) from the intrusion moisture and dirt and further dissipate the heat into the environment. During the operation of the electric motor (1’) a large amount of heat is generated. Therefore, the electric motor (1’) must be sufficiently cooled through the casing. The heat dissipation is of utmost importance in view of the thermal protection of the electric motor and its performance. Figures 4 to 5 show a production process of the electric motor (1’). In this production process, the casing (5’) is separately formed through die casting or injection moulding. Next, the casing (5’) is press-fitted onto the outer stator (2’). In an alternative production process (not shown), the casing (5’) is fitted onto the outer stator (2’) through heat shrinking. In another alternative production process (not shown), the casing (5’) is directly formed onto the outer stator (2’) through Aluminum injection molding.

US 2014/0117797A1 discloses an electric motor.

A common problem with the prior art electric motor (1’) is that the aforementioned production processes are complicated and cost intensive. Moreover the production process is vulnerable to faults which cause a reduction in the heat dissipation and an increase in the vibration of the electric motor (1’) during the operation. For instance, the outer stator may receive deformations during the Aluminum injection molding of the casing (5’) due to the high temperatures about 600 to 700 degrees Celsius and thus the gap between the outer stator (2’) and the inner rotor may not be accurately adjusted. In contrast thereto, in the heat shrinking process of the casing (5’) or in the press-fitting process of the casing (5’), the contact established between the casing (5’) and the outer stator (2’) may be poor and thus the heat dissipation may become insufficient and also vibrations may occur during the operation.

An objective of the present invention is to provide an electric motor which overcomes the problems of the prior art in a cost effective way and which enables an improved production and assemblage and an improved cooling performance.

This objective has been achieved by the electric motor as defined in claim 1. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.

In the electric motor of the present invention the casing includes a first half casing which is adapted to receive and contact the first circumferential half of the core, a second half casing which is adapted to receive and contact the second circumferential half of the core and an attachment means which is adapted to detachably attach the first half casing to the second half casing and to press the first half casing and the second half casing onto the core.

A major advantageous effect of the present invention is that the outer stator can be easily assembled with the casing. Another major advantageous effect of the present invention is that the outer stator can be easily disassembled from the casing. Another major advantageous effect of the present invention is that the contact between the core and the casing has been improved. Thereby, the heat can be more effectively dissipated into the environment. Thereby also the outer stator can be prevented from vibrating inside the casing. Another major advantageous effect of the present invention is that the need for using a heat source for the heat shrinking process has been obviated. Another major advantageous effect of the present invention is that the need for using a press for the press fitting process has also been obviated. Another major advantageous effect of the present invention is that the need for reworking the gap between the outer stator and the inner rotor has been eliminated or reduced as much as possible. Thereby, the production costs can be reduced both in labor and material.

In an embodiment, the first half casing and the second half casing are arc shaped. The first half casing and the second half casing together form a two-piece tubular casing. Of course, other electrical parts and/or ventilating parts may be mounted onto the casing. In this embodiment, the first half casing and the second half casing respectively receive the upper circumferential half and the lower circumferential half of the outer stator. This embodiment is particularly advantageous as the first half casing and the second half casing can be easily assembled with or dissembled form the outer stator. Thereby, the contact between the core and the casing can be accurately adjusted. Thereby, also the vibrations can be effectively eliminated and the heat can be more effectively dissipated into the environment.

In other alternative embodiments, each of the first half casing and the second half casing may include one or more separate pieces which can be detachably attached to each other. These embodiments are particularly advantageous as the number of pieces can be flexibly adjusted in accordance with the size and shape of the electric motor.

In another embodiment, the first half casing and second half casing are detachably attached and pressed onto the core through one or more screw connections. This embodiment is particularly advantageous as the stator can be easily assembled with or disassembled from the casing through the screw connections. Thereby, the electric motor can be easily serviced. Thereby, also the contact between the casing and the core can be accurately adjusted through the screw connections so as to increase the heat dissipation and reduce the vibrations.

In an embodiment, the first half casing and the second half casing can be guidably joined along the axial direction through a guiding means. This embodiment is particularly advantageous as the first half casing and the second half casing can be easily aligned prior to the attachment.

In an alternative embodiment, the first half casing and the second half casing can be pivotally joined about the axial direction through a pivoting means. This embodiment is particularly advantageous as the first half casing and the second half casing are movably held together through the pivoting means prior to the attachment. Thereby, the casing can be more easily handled.

Additional features and additional advantageous effects of the electric motor of the present invention will become more apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:

Figure 1 - is a perspective view of an electric motor according to the prior art;

Figure 2 - is a perspective view of the casing of the electric motor in Fig. 1;

Figure 3 - is a perspective view of the outer stator of the electric motor in Fig. 1;

Figure 4 - is a perspective view of the production process of the electric motor in Fig. 1, prior to press-fitting the casing onto the outer stator;

Figure 5 - is a perspective view of the production process of the electric motor in Fig. 1, after the casing has been press-fitted onto the outer stator;

Figure 6 - is a perspective view of an electric motor according to an embodiment of the present invention;

Figures 7 to 8 - are perspective views of the production process of the electric motor in Fig. 6;

Figure 9 - is a perspective view of an electric motor according to another embodiment of the present invention;

Figures 10 to 12 - are perspective views of the production process of the electric motor in Fig. 9;

Figure 13 - is a perspective view of an electric motor according to another embodiment of the present invention;

Figures 14 to 16 are perspective views of the production process of the electric motor in Fig. 13.

The reference signs appearing on the drawings relate to the following technical features.

Electric motor
Outer stator
Core
Coil
Casing

5a. Cooling fin
6. 1^st half casing

7. 2^nd half casing

8. Attachment means

9. Screw connection

9a. Screw

9b. Screw tab

10. Guiding means

11. Pivoting means

11a. Hinge

The electric motor (1) comprises an outer stator (2) which includes a core (3) and coils (4) which are disposed onto the core (3), a shaft (not shown), an inner rotor (not shown) which is disposed around the shaft and a casing (5) which is adapted to enclose the circumferential surface of the outer stator (2), a front cap (not shown) and a rear cap (not shown) which cover the front aperture and the rear aperture of the casing (5) respectively (Fig. 6, Fig.9 and Fig. 13).

In the electric motor (1) of the present invention, the casing (5) includes a first half casing (6) which is adapted to receive and contact the first circumferential half of the core (3), a second half casing (7) which is adapted to receive and contact the second circumferential half of the core (3) and an attachment means (8) which is adapted to detachably attach the first half casing (6) to the second half casing (7) and to press the first half casing (6) and the second half casing (7) onto the core (3) (Fig. 6, Fig. 9 and Fig. 13).

In an embodiment, the attachment means (8) comprises a plurality of screw connections (9) (Fig. 7, Fig. 11 and Fig. 15).

In another embodiment, each screw connection (9) comprises a screw (9a) and two screw tabs (9b) which are disposed onto the first half casing (6) and the second half casing (7) respectively (Fig. 7, Fig. 10 and Fig. 14).

In another embodiment, the electric motor (1) further comprises a guiding means (10) which is adapted to guidably join the first half casing (6) with the second half casing (7) along the axial direction (Fig. 10 and Fig. 11).

In another embodiment, each guiding means (10) is defined through two screw tabs (9b) which form-fittingly engage and are disposed onto the first half casing (6) and the second half casing (7) respectively. In this embodiment, one of the screw tabs (9b) has a u-shaped form and the other one of the screw tabs (9b) has a straight form (Fig. 10 and Fig. 11).

In another embodiment, the electric motor (1) further comprises a pivoting means (11) which is adapted to pivotally join about the axial direction the first half casing (6) with the second half casing (7) (Fig. 14 and Fig. 15).

In another embodiment, the pivoting means (11) comprises one or more hinges (11a) (Fig. 14 and Fig. 15).

In another embodiment, the casing (5) comprises a plurality of cooling fins (5a) which are adapted to radiate the thermal energy into the environment (Fig. 6, Fig. 9 and Fig. 13).

In the subsequent description, alternative methods of producing the electric motor (1) will be briefly explained by way of example. First, the first half casing (6) and the second half casing (7) are separately provided for instance by die casting or metal injection molding (Fig. 7, Fig. 10 and Fig 14). Next, the outer stator (2) is placed into the second half casing (7) (Fig. 7, Fig. 11 and Fig. 15). Next, the first half casing (6) is placed onto the outer stator (2) (Fig. 8, Fig. 12 and Fig. 16). Next, the first half casing (6) and the second half casing (7) are attached through the screw connections (9) and firmly pressed onto the core (3) (Fig. 6, Fig. 9 and Fig. 13). Next, the inner rotor is placed into the outer stator (2) and the first cap and the second cap are fixed to the apertures of the casing (5) respectively.

A major advantageous effect of the present invention is that the outer stator (2) can be easily assembled with or disassembled from the casing (5), including the first half casing (6) and the second half casing (7). Another major advantageous effect of the present invention is that the contact between the core (3) and the casing (5) has been improved. Thereby, the heat can be more effectively dissipated into the environment. Thereby also the outer stator (2) can be prevented from vibrating inside the casing (5) during the operation. Other advantageous effects of the present invention can be taken from the above described embodiments.

Claims

An electric motor (1) comprising an outer stator (2) which includes a core (3) and coils (4) which are disposed onto the core (3), a shaft, an inner rotor which is disposed around the shaft and a casing (5) which is adapted to enclose the circumferential surface of the outer stator (2), characterized in that the casing (5) comprises

- a first half casing (6) which is adapted to receive and contact the first circumferential half of the core (3),

- a second half casing (7) which is adapted to receive and contact the second circumferential half of the core (3) and

- an attachment means (8) which is adapted to detachably attach the first half casing (6) to the second half casing (7) and to press the first half casing (6) and the second half casing (7) onto the core (3).
The electric motor (1) according to claim 1, characterized in that the attachment means (8) comprises a plurality of screw connections (9).
The electric motor (1) according to claim 1 or 2, characterized in that a guiding means (10) which is adapted to guidably join the first half casing (6) with the second half casing (7) along the axial direction.
The electric motor (1) according to claim 1 or 2, characterized in that a pivoting means (11) which is adapted to pivotally join about the axial direction the first half casing (6) with the second half casing (7).