CN115498803A

CN115498803A - Motor and automobile seat comprising same

Info

Publication number: CN115498803A
Application number: CN202211310335.4A
Authority: CN
Inventors: 龚乘龙; 廖小兵; 田立; 何智
Original assignee: Guangdong Zhaoqing L&V Co Ltd
Current assignee: Guangdong Zhaoqing L&V Co Ltd
Priority date: 2022-10-25
Filing date: 2022-10-25
Publication date: 2022-12-20

Abstract

The invention relates to a motor with high electromagnetic compatibility level, which comprises a stator assembly, a rotor assembly and an end cover assembly, wherein the stator assembly comprises a metal shell, the rotor assembly comprises a rotor core and a rotor shaft, the end cover assembly comprises an end cover, the shell comprises a first end provided with a bearing cavity and an open second end opposite to the first end, the motor is also provided with a metal sealing cover, the periphery of the sealing cover is provided with a plurality of retaining protruding pieces, the circumferential outer surface of the end cover is provided with a plurality of positioning protrusions, the end edge of the second end of the shell is provided with positioning notches matched with the positioning protrusions and retaining notches matched with the retaining protruding pieces, so that the rotor assembly and the end cover assembly are completely sealed in the shell through the sealing cover, and the motor is in a metal closed structure. The invention also relates to an automobile seat comprising the motor. By adopting the motor provided by the invention, the electromagnetic radiation of the motor can be inhibited to a greater extent, and a high EMC level is obtained.

Description

Motor and automobile seat comprising same

Technical Field

The invention relates to the technical field of motors, in particular to a motor with high electromagnetic compatibility (EMC) level and an automobile seat comprising the motor.

Background

With the development of science and technology, more and more functions are integrated in the vehicle seat, and in order to realize the functions of the vehicle seat, the motor is more and more widely applied to the field of vehicles, in particular to the vehicle seat. As a seat motor used in an automobile, a working environment has a very high demand for Electromagnetic Compatibility (EMC) of the motor. However, the motors known from the prior art do not satisfy the requirements for high EMC levels, in particular in the field of vehicle seats, for the most part, since these motors, in particular dc brushed motors, cannot be shielded from the effects of electromagnetic waves by commutation and electromagnetic propagation.

Electric machines typically include a stator assembly having a metal housing, a rotor assembly including a rotor (collectively formed by a rotor core and a rotor shaft), and an end cap assembly. For example, the end covers of the currently known electric machines are arranged substantially outside the casing of the electric machine, which obviously does not allow the electric machine to form an all-metal enclosure as a whole, and is therefore not conducive to the suppression of electromagnetic radiation. In addition, most brushed motors have large commutation sparks due to large vibration of the rotor during operation, instability during commutation of the motor, and conventional air gap structures, which are detrimental to the suppression of electromagnetic radiation from the motor.

Therefore, there is a need to propose an improved electric machine which enables a greater suppression of the electromagnetic radiation of the electric machine from one or more of the different aspects mentioned above, in order to obtain an electric machine with a high EMC level, so that it can be better applied in the automotive field.

Disclosure of Invention

The present invention has been made in view of such a background. According to one aspect of the present invention, there is provided an electric machine with a high level of electromagnetic compatibility, comprising a stator assembly, a rotor assembly and an end cap assembly, the stator assembly comprising a metallic casing, the rotor assembly comprising a rotor core and a rotor shaft, the end cap assembly comprising an end cap, the casing comprising a first end provided with a bearing cavity and an open second end opposite to the first end, the electric machine further being provided with a metallic cover, the cover being provided on its periphery with a plurality of retention tabs, the end cap being provided on its circumferential outer surface with a plurality of positioning projections, and at an end edge of the second end of the casing with positioning notches for cooperating with the positioning projections of the end cap and with retention notches for cooperating with the retention tabs, so as to completely enclose the rotor assembly and the end cap assembly within the casing by the cover, thereby giving the electric machine an overall metallic closed structure.

Advantageously, the retention tab comprises a retaining structure capable of preventing the cover from falling out of the housing in a direction away from the housing when the retention tab is seated in the corresponding retention notch.

Advantageously, a bearing for rotatably supporting one end of the rotor shaft is arranged in the bearing chamber, the circumferential outer surface of the bearing comprising a first length section intended to cooperate with the inner wall of the bearing chamber and a second length section extending beyond the bearing chamber.

Advantageously, a plurality of projecting teeth spaced apart from one another are provided on the circumferential outer surface of the bearing along the first length section.

Advantageously, a circuit board is fixed to the end cap, on which circuit board a plurality of grounding wires are arranged, which are intended to be in contact with the metal housing to achieve a plurality of grounds.

Advantageously, the electric machine is a dc brushed electric machine, the stator assembly further comprises a plurality of magnetic shoes circumferentially arranged within the housing, the end cap assembly further comprises a brush assembly, and the rotor assembly further comprises a commutator fixed to a rotor shaft.

Advantageously, the rotor assembly defines a rotor center, the magnetic tiles define arc-shaped inner edges defining a circular arc center, wherein an eccentricity is defined between the circular arc center and the rotor center, so that an air gap is formed between the magnetic tiles and the rotor core, wherein the air gap is gradually increased from the middle of the magnetic tiles to two sides (namely, the middle is thin and the two sides are thick).

Advantageously, the brush assembly comprises a brush holder and a carbon brush fixed to the brush holder, the brush holder comprising a swing arm for holding the carbon brush and a spring plate fixed to the end cap, wherein the spring plate is provided with a material removal portion, the size of which can be adjusted to adjust the force of the carbon brush on the commutator surface.

Advantageously, the material removal portion is an elongated hole formed on the spring plate and/or a notch formed at an outer periphery of the spring plate.

According to another aspect of the invention, a vehicle seat is also proposed, which comprises the above-mentioned motor.

Compared with the prior art, the structure for the motor can achieve at least one of the following technical effects: the end cover and the rotor assembly can be completely wrapped in the metal shell by utilizing the metal sealing cover and the lengthened metal shell structure, so that the whole motor is in a metal closed structure, and the electromagnetic radiation of the motor to the outside is effectively reduced; an air gap with a thin middle part and thick two sides is formed between the magnetic shoe and the rotor by adopting the eccentric magnetic shoe, so that a surface magnetic curve with a specific shape is formed after magnetization, the cogging torque fluctuation in the rotation process of the motor is reduced, and the electromagnetic radiation of the motor is favorably inhibited; through the favorable structural design of the bearing and the brush carrier, the vibration of the rotor is reduced, the motor moves more stably in the reversing process, and the reversing spark in the working process of the motor is improved; and multiple positions of the circuit board are grounded, so that the electromagnetic radiation can be inhibited.

Drawings

The above and other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

fig. 1 shows an exploded view and an assembled view of a prior art electric machine;

fig. 2 shows an exploded view and an assembled view of an electrical machine according to an embodiment of the invention;

figures 3a to 3c show a schematic view of a metallic cover before the retention tab is bent, after the retention tab is bent and when the whole is assembled on the housing, respectively;

fig. 4a shows the structure of the housing in a perspective view; FIG. 4b shows the structure of the end cap in perspective view;

figure 5 shows a schematic cross-sectional view of a housing of the electrical machine included in figure 2 and an enlarged partial view of a bearing chamber (in which the bearing is received) provided at one end of the housing;

6a-6b show perspective and cross-sectional views, respectively, of a bearing received in the bearing cavity shown in FIG. 5;

FIG. 7a shows a schematic cross-sectional view of a magnetic shoe fixedly arranged within a housing; fig. 7b shows the positional relationship of the rotor core with respect to the magnetic shoe; figure 7c shows an eccentric arrangement between the centre of the rotor and the centre of the arc of the magnetic shoe;

fig. 8 is a schematic structural view showing a brush holder to which a carbon brush is fixed; and

fig. 9a shows a schematic view of a circuit board intended to be fixed to an end cap; and figure 9b shows a schematic view of the assembly between the circuit board and the end cap.

All the figures are purely diagrammatic and not drawn to scale, and moreover they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely mentioned. That is, the present invention may include other components in addition to those shown in the drawings.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention to those skilled in the art. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following aspects, features, embodiments and advantages are merely illustrative and should not be considered elements or limitations of the claims except where explicitly recited in a claim. Terms such as "first," "second," and the like are used hereinafter to describe elements of the present application and are used only to distinguish one element from another without limiting the nature, sequence, order, or number of such elements. In addition, it should be pointed out that in the present description identical and/or functionally identical features are provided with the same or similar reference signs.

As shown in fig. 1, there is shown an exploded view and an assembled view of a prior art electric machine 1' (in particular a permanent magnet dc brushed electric machine). The motor 1 'comprises a stator assembly, a rotor assembly and an end cover assembly, wherein the stator assembly comprises a metal shell 2' and four magnetic shoes 3 'fixed in the shell 2', and the rotor assembly comprises a rotor core 4', a rotor shaft 6' and a commutator 7 'fixed on the rotor shaft 6'. The end cap assembly comprises an end cap 5' and a brush holder 9' which can be fastened to the end cap 5', the brush holder 9' having fixedly held thereon a carbon brush 8' which is intended to be in contact with a commutator 7' on the rotor shaft 6 '. However, as can be seen from the motor 1' shown in fig. 1 (especially referring to the assembly schematic diagram of the motor), after the stator assembly, the rotor assembly and the end cap assembly are finally assembled, the end cap 5' is located substantially outside the housing 2', which makes the motor unable to form an all-metal enclosed space, resulting in the motor radiating strong electromagnetic waves to the outside, thereby affecting the normal operation of the electronic instruments on the automobile, which thus greatly limits the application of the motor in the automobile field.

To this end, the invention proposes a design which is optimized with regard to the structure of the electric machine from a number of different aspects. The motor disclosed by the invention is compact in structure and convenient to mount, and can meet the requirement of high EMC grade of the motor.

Referring specifically to fig. 2, a motor 1 according to an embodiment of the invention is shown, in particular as exemplified by a dc brushed motor. Similar to the motor structure shown in fig. 1, the motor according to the present invention shown in fig. 2 comprises a stator assembly, a rotor assembly and an end cap assembly, wherein the stator assembly comprises a metallic outer shell 2 and four magnetic tiles 3 fixedly arranged circumferentially within the outer shell. It will be appreciated that the number of magnetic shoes may be two, four or other suitable number, etc., depending on the different motor configuration. In addition, the rotor assembly includes a rotor core 4, a rotor shaft 6, and a commutator 7 fixed to the rotor shaft 6. The end cap assembly comprises an end cap 5 and a brush holder 9 which can be fastened to the end cap 5, on which brush holder 9a carbon brush 8 can be fixedly held, which is intended to be in contact with the commutator 7 on the rotor shaft 6.

Compared with the motor in the prior art, the motor greatly improves and increases the EMC level of the motor from the two aspects of improving the commutation spark of the motor and enabling the motor to be in a metal closed structure to shield external electromagnetic radiation to a great extent. Next, structural improvements of various aspects of the motor will be described in detail.

With particular reference to fig. 4a and 5, the housing 2 of the electric machine comprises a first end provided with a bearing chamber 13 and a second end, opposite said first end, open. Within this bearing chamber 13 is a bearing 12, for example an oil-impregnated bearing, for rotatably supporting one end of the rotor shaft, the outer surface of the bearing 12 comprising a first length section L1 intended to cooperate with the inner wall of said bearing chamber 13 and a second length section L2 extending beyond said bearing chamber 13 (see fig. 6a-6 b), a stop 14 being formed between said first and second length sections L1, L2 due to the change in the diameter of the outer surface of the bearing for providing a stop for the bearing 12 received in the bearing chamber 13. Compared with the common oil-containing bearing known in the prior art, the bearing provided by the invention is provided with the lengthened section extending beyond the bearing cavity, so that the supporting area between the rotor shaft 6 of the motor and the bearing 12 can be increased under the condition that the space size of the bearing cavity is limited, the integral contact rigidity is increased, the natural frequency of the rotor in a constraint state is changed, the rotor is beneficial to avoiding the resonance frequency, the vibration of the rotor is reduced, the movement of the motor in the reversing process is more stable, the reversing spark of the motor in the working process is improved, and the electromagnetic radiation of the motor is favorably inhibited. Furthermore, advantageously, in order to enable a more stable retention of the bearing 12 within the bearing chamber 13, a plurality of projecting teeth 15 (see fig. 6 a) spaced apart from one another are provided on the circumferential outer surface of the bearing 12 along said first length section L1.

As discussed previously, in the machine shown in figure 1, the end of the end cap 5' is enclosed by a metal cover 10', the cover 10' being provided with two lugs 10a ' on its periphery which are intended to be interference press-fitted into the notches of the end cap 5 '. However, since the housing 2 'in fig. 1 does not completely enclose the end cap 5', the end cap is located substantially outside the housing, which is very disadvantageous for suppressing electromagnetic radiation of the electric machine.

To this end, the invention proposes an improved structure. With particular reference to fig. 3a-3c and 4a-4b, the motor according to the invention is provided with a metallic cover 10, the cover 10 having external dimensions close to the dimensions of the internal space of the casing 2, so as to allow the cover 10 to be embedded in the end of the casing 2 and to form a closed space when assembled with the casing. Specifically, the cover 10 is provided with a plurality of holding tabs 10a on the periphery thereof, the end cap 5 is provided with a plurality of positioning protrusions 5a (see fig. 4 b) on the circumferential outer surface thereof, and a positioning notch 2a for engaging with the positioning protrusions 5a of the end cap 5 and a holding notch 2b for engaging with the holding tabs 10a are provided at an end edge of the second end (i.e., the end opposite to the first end at which the bearing chamber is provided) of the housing 2, so as to completely enclose the rotor assembly and the end cap assembly within the housing 2 by the cover 10 (as shown in fig. 2).

Referring particularly to fig. 3a-3b, the cover 10 and the retention tabs 10a thereon are preferably integrally formed panels that require only the retention tabs 10a on the cover 10 to be bent over and snapped into corresponding retention notches 2b in the housing 2 when the cover 10 is mounted to the housing 2. The holding tab 10a includes a coming-off prevention structure so that the cover 10 can be prevented from coming off the housing 2 in a direction away from the housing 2 when the holding tab 10a is placed in the corresponding holding notch 2 b. As one example, the anti-slip structure may be a circular protrusion. Of course, other anti-falling structures are possible as long as the function of preventing the sealing cover from falling off accidentally is achieved.

Since the end cover 5 can be held on the housing 2 by the positioning projections 5a, and since the cover 10 can abut against the end surface of the end cover 5 to firmly hold the end cover 5, the housing 2, and the cover 10 as a whole, the motor as a whole is of a metal enclosed structure, and electromagnetic radiation to the outside of the motor is advantageously reduced or suppressed.

With continued reference to fig. 7a-7c, the rotor assembly defines a rotor center O1, and each of the magnetic tiles 3 circumferentially disposed inside the housing 2 defines an arcuate inner edge defining an arc center O2 having a radius R1, and the rotor core 4 has a radius R2, wherein an eccentricity e is defined between the arc center O2 and the rotor center O1 such that an air gap 20 is formed between the magnetic tiles 3 and the rotor core 4 that gradually increases from the middle of the magnetic tiles to both sides (i.e., thin in the middle and thick on both sides). Unlike the uniform air gap commonly adopted in the prior art, the air gap structure enables a surface magnetic curve with a specific shape to be formed after magnetization, so that the cogging torque fluctuation in the motor rotation process is reduced, the electromagnetic radiation of the motor is greatly inhibited, and the improvement of the EMC level of the motor is very beneficial.

As discussed above, as a dc brushed electric machine, the end cap assembly of the electric machine may include a brush assembly. As shown in fig. 8, the brush assembly includes a brush holder 9 and a carbon brush 8 fixed to the brush holder 9. The brush holder 9 includes a swing arm 9a for holding the carbon brush 8 and a spring plate 9b fixed to the end cap 5, for example, a through hole 16 for passing a pin (not shown) is provided on the spring plate 9b to fix the brush holder 9 to the end cap 5 by the pin. Advantageously, the elastic sheet 9b is further provided with a material removing part. Preferably, the material removing part is a waist-shaped long hole 17 formed on the elastic sheet and/or a notch 18 formed at the outer periphery of the elastic sheet. For example, by changing the size of the long hole, the elastic force of the swing arm can be adjusted to adjust the acting force of the carbon brush on the surface of the commutator, so that the commutation spark of the motor can be improved.

With continued reference to fig. 9a-9b, a circuit board 11 is fixed or soldered to the end cap 5 of the electric machine, which circuit board is provided with a plurality of grounding wires 19, said plurality of grounding wires 19 being intended to be in contact with said metallic housing 2 for multiple grounding. This is also different from the circuit board structure with single ground wire commonly used in the prior art, which allows better suppression of electromagnetic radiation by grounding the circuit board with multiple (two or more ground wires) housings. In addition, multiple grounding points can enable all units of the circuit to have more common reference zero potential, so that the circuit system can work stably.

In the actual assembly process of the motor, after the stator assembly (press-fitting of a bearing in a shell, installation of magnetic shoes and the like), the rotor assembly (installation of a commutator, winding of a rotor and the like) and the end cover assembly (press-fitting of the bearing, installation and fixation of a brush holder assembly, welding of a circuit board and the like) are assembled respectively, the rotor assembly and the end cover assembly are installed in the shell, and finally a metal sealing cover (such as an iron cover) is attached to the surface of the end cover and fixedly connected with the shell, so that the integral sealing cover of the motor is completed. The formed integral metal closed structure and the beneficial structural improvement of the motor parts can shield the electromagnetic radiation of the motor to the outside to a great extent, improve the commutation spark of the motor and greatly improve the EMC grade of the motor.

It should be noted that the above-described embodiments should be regarded as merely illustrative, and the present invention is not limited to these embodiments. Various changes and modifications may be made by those skilled in the art without departing from the scope or spirit of the invention in view of the contents of this specification. With a true scope of the invention being indicated by the following claims and their equivalents.

Claims

1. An electric machine (1) comprising a stator assembly, a rotor assembly and an end cap assembly, the stator assembly comprising a metallic housing (2), the rotor assembly comprising a rotor core (4) and a rotor shaft (6), the end cap assembly comprising an end cap (5), the housing (2) comprising a first end provided with a bearing chamber (13) and an open second end opposite to the first end, characterized in that the electric machine (1) is further provided with a metallic cover (10) provided with a plurality of holding tabs (10 a) on its periphery, the end cap (5) being provided with a plurality of positioning protrusions (5 a) on its circumferential outer surface, positioning notches (2 a) for cooperating with the positioning protrusions (5 a) of the end cap and holding notches (2 b) for cooperating with the holding tabs (10 a) being provided at an end edge of the second end of the housing (2) to completely enclose the rotor assembly and the end cap assembly within the housing through the cover (10), thereby rendering the electric machine entirely of a metallic closed structure.

2. The electrical machine (1) according to claim 1, characterized in that the retention tab (10 a) comprises an anti-disengagement structure able to avoid the cover (10) coming out of the casing (2) in a direction away from the casing when the retention tab (10 a) is seated in the corresponding retention notch (2 b).

3. An electric machine (1) as claimed in claim 1, characterized in that a bearing (12) for rotatably supporting one end of the rotor shaft (6) is arranged in the bearing chamber (13), the outer surface of which bearing comprises a first length section (L1) intended to cooperate with the inner wall of the bearing chamber and a second length section (L2) extending beyond the bearing chamber.

4. The electrical machine (1) according to claim 3, characterized in that a plurality of protruding teeth (15) spaced from each other are provided on the circumferential outer surface of the bearing (12) along the first length section (L1).

5. An electric machine (1) as in claim 1, characterized by a circuit board (11) fixed on the end cover (5) and provided with a plurality of grounding wires (19) intended to be in contact with the metallic casing (2) to achieve a plurality of grounds.

6. The electrical machine (1) according to any of claims 1 to 5, characterized in that the electrical machine is a direct current brushed electrical machine, the stator assembly further comprising a plurality of magnetic tiles (3) arranged circumferentially within the housing, the end cap assembly further comprising a brush assembly, the rotor assembly further comprising a commutator (7) fixed to a rotor shaft (6).

7. The electric machine (1) according to claim 6, characterized in that the rotor assembly defines a rotor center (O1), the magnet tiles (3) define an arc-shaped inner edge defining an arc center (O2), wherein an eccentricity (e) is defined between the arc center and the rotor center, such that an air gap (20) is formed between the magnet tiles and the rotor core, which gradually increases from the middle of the magnet tiles to both sides.

8. An electric machine (1) as claimed in claim 6, characterized in that the brush assembly comprises a brush holder (9) and a carbon brush (8) fixed to the brush holder, the brush holder comprising a swing arm (9 a) for holding the carbon brush and a spring plate (9 b) fixed to the end cap, wherein the spring plate is provided with a material removal portion, the size of which can be adjusted to adjust the force of the carbon brush on the commutator surface.

9. The electrical machine (1) according to claim 8, characterized in that the material removal is an elongated hole (17) formed on the spring plate (9 b) and/or a notch (18) formed at the outer periphery of the spring plate.

10. A car seat, characterized in that it comprises an electric machine (1) according to any one of claims 1 to 9.