Motor

Abstract

The utility model discloses a motor, comprising a stator assembly comprising a housing which comprises a rear end cover; the rotor assembly is mounted in the stator assembly; the rotor assembly comprises a rotating shaft; the lining is fixed on the rear end cover; the bearing comprises a first bearing ring and a second bearing ring which can rotate relative to each other, the first bearing ring is fixedly connected with the rear end part of the rotating shaft, the second bearing ring is fixedly connected with the bushing, and the radial run-out of the rear end of the rotating shaft in the rotating process is limited through the support of the bushing and the bearing; and the encoder comprises an encoding fixing piece and an encoding rotating piece, the encoding fixing piece is fixed on the bushing, and the encoding rotating piece is fixed at the rear end of the rotating shaft. Large through hole radial avoidance does not need to be made in the middle of the encoder rotating piece installed at the rear end of the rotating shaft, so that the radial size of the encoder can be reduced to a great extent based on the scheme, and the effect of reducing the use cost of the encoder is further achieved.

Description

Technical Field

[0001] This application relates to the technical field of power equipment, and particularly to an electric motor. Background Art

[0002] Existing screen printing equipment is equipped with a direct drive motor. Using the direct drive method, the rotational speed is relatively low, and it has a high output torque and overload capacity. The motor is usually designed in a short and fat structure, that is, the radial dimension of the motor rotor is relatively large. The turntable workbench of the equipment is directly connected to the motor rotor through a rotor connecting piece. To ensure the stability of the turntable during operation, the radial dimension of the rotor connecting piece is also relatively large, increasing the mating surface with the turntable workbench, and the radial dimension of the part where the front end of the rotating shaft is connected to the rotor connecting piece also needs to be increased synchronously.

[0003] The encoder in the motor is a key component, which can realize reading the change of the workbench angle and assist the equipment to achieve precise control. Currently, the rotating part of the encoder of the motor applied on the screen printing equipment is installed on the rotor connecting piece, and the fixed part of the encoder is installed on the front end cover of the motor. To match the structural characteristics of the large-diameter rotor connecting piece in the above-mentioned motor, the existing encoder can only select a large-size structure (a large through hole needs to be made in the center of the encoder to avoid the rotating shaft), which leads to the problem of high cost of the adopted encoder. Summary of the Utility Model

[0004] The purpose of the embodiments of the present utility model is to provide an electric motor that can solve the above problems existing in the prior art.

[0005] To achieve the above object, this application adopts the following technical solutions:

[0006] An electric motor, comprising:

[0007] A stator assembly, including a housing, and the housing includes a rear end cover;

[0008] A rotor assembly, installed inside the stator assembly; the rotor assembly includes a rotating shaft;

[0009] A bushing, fixed to the rear end cover;

[0010] A bearing, including a first bearing ring and a second bearing ring that can rotate relative to each other. The first bearing ring is fixedly connected to the rear end of the rotating shaft, and the second bearing ring is fixedly connected to the bushing. The radial runout of the rear end of the rotating shaft during rotation is restricted by the support of the bushing and the bearing;

[0011] An encoder, including a coding fixed part and a coding rotating part. The coding fixed part is fixed to the bushing, and the coding rotating part is fixed to the rear end of the rotating shaft.

[0012] Optionally, a plurality of positioning threaded holes are provided on the rear end cover, through holes are correspondingly provided on the bushing, and locking screws pass through the through holes and are threadedly connected to the positioning threaded holes to fix the bushing to the rear end cover; wherein, the locking screws are in clearance fit with the through holes.

[0013] Optionally, the bushing protrudes from the outer surface of the rear end cover to provide a contact point for the runout test work.

[0014] Optionally, the bushing includes a fixing plate and a connecting convex ring protruding from the surface of the fixing plate, a through hole in clearance fit with the connecting convex ring is provided on the rear end cover, the fixing plate is fixed to the outer surface of the rear end cover, and the connecting convex ring extends into the through hole to be fixedly connected to the second bearing ring.

[0015] Optionally, the bearing is an angular contact bearing, an outer shoulder is provided on the side wall of the rotating shaft, an inner shoulder is provided on the inner wall of the connecting convex ring, the first bearing ring is sleeved on the rotating shaft and contacts the outer shoulder, and the second bearing ring is embedded and installed in the connecting convex ring and contacts the inner shoulder, and the axial movement of the bearing is restricted by the outer shoulder and the inner shoulder.

[0016] Optionally, a mounting hole is provided in the center of the fixing plate, the coded rotating part is fixed to the end face of the rotating shaft through the mounting hole, and the coded fixing part is fixed to the fixing plate.

[0017] Optionally, the bearing is a deep groove ball bearing, an outer shoulder is provided on the side wall of the rotating shaft, a bearing gland is installed on the end face of the rotating shaft, the first bearing ring is sleeved on the rotating shaft, and the two end faces of the first bearing ring respectively abut against the outer shoulder and the bearing gland, and the axial movement of the bearing is restricted by the outer shoulder and the bearing gland.

[0018] Optionally, a mounting hole is provided in the center of the fixing plate, the coded rotating part is fixed to the end face of the bearing gland through the mounting hole, and the coded fixing part is fixed to the fixing plate.

[0019] Optionally, a counterbore circumferentially arranged around the mounting hole is provided on the side of the fixing plate facing away from the rotating shaft, and the coded fixing part is embedded and fixed in the counterbore.

[0020] Optionally, the rear end cover is made of an aluminum alloy structure, and the bushing is made of a cast iron structure.

[0021] The beneficial effects of the present application are as follows: The present utility model provides a motor. A bushing and a bearing are installed on the rear end cover of the motor, and the bearing is fixedly connected to the rotating shaft. The support of the bushing and the bearing restricts the radial runout of the rear end of the rotating shaft, ensuring the stability of the rotation of the rear end of the rotating shaft. On the basis of ensuring the stability of the rotation of the rear end of the rotating shaft, the coded rotating part of the encoder is installed at the rear end of the rotating shaft, and the coded fixing part is installed on the bushing to realize the use function of the encoder. In this solution, since the coded rotating part is installed at the rear end of the rotating shaft, compared with the traditional solution of installing the rotor connecting part at the front end, there is no need to make a large through-hole radial avoidance in the middle of the encoder rotating part installed at the rear end of the rotating shaft, and the encoder fixing part installed on the bushing will not interfere with the rotating shaft, so there is no need to make an avoidance. Therefore, based on this solution, the radial dimension of the encoder can be greatly reduced, and the effect of reducing the use cost of the encoder can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present application will be further described in detail below with reference to the drawings and embodiments.

[0023] Figure 1 It is an axial sectional view of one implementation manner of the motor described in the embodiment of the present application;

[0024] Figure 2 is Figure 1 an enlarged view of area A in

[0025] Figure 3 It is an axial sectional view of another implementation manner of the motor described in the embodiment of the present application;

[0026] Figure 4 is Figure 3 an enlarged view of area B in

[0027] In the figure:

[0028] 1. Rotor assembly; 11. Rotating shaft; 111. Outer shoulder; 112. Bearing gland; 12. Rotor core; 13. Rotor connecting part; 2. Stator assembly; 21. Housing; 211. Main housing; 212. Front end cover; 213. Rear end cover; 22. Stator core; 3. Bushing; 31. Fixing plate; 32. Connecting convex ring; 33. Inner shoulder; 34. Sunk groove; 4. Bearing; 41. First bearing ring; 42. Second bearing ring; 5. Encoder; 51. Coded rotating part; 52. Coded fixing part. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the technical problems solved by this application, the technical solutions adopted, and the achieved technical effects clearer, the following further describes in detail the technical solutions of the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of this application.

[0030] In the description of this application, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0031] In this application, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above", and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below", and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature.

[0032] There is a direct drive motor applied on the existing screen printing equipment. Adopting the direct drive method, the rotational speed is relatively low, and it has a relatively high output torque and overload capacity. The motor is usually designed in a short and stout structure, that is, the radial dimension of the motor rotor is relatively large. The turntable workbench of the equipment is directly connected to the motor rotor through a rotor connecting piece. To ensure the stability of the turntable during operation, the radial dimension of the rotor connecting piece is also relatively large synchronously, increasing the mating surface with the turntable workbench, and the radial dimension of the part where the front end of the rotating shaft is connected to the rotor connecting piece also needs to be increased synchronously.

[0033] The encoder in the motor is a key component, which can realize reading the change of the workbench angle and assist the equipment to achieve precise control. Currently, the rotating part of the encoder of the motor applied on the screen printing equipment is installed on the rotor connecting piece, and the fixed part of the encoder is installed on the front end cover of the motor. To match the structural characteristics of the large-diameter rotor connecting piece in the above-mentioned motor, the existing encoder can only select a large-size structure (a large through hole needs to be made in the center of the encoder to avoid the rotating shaft), which further leads to the problem of relatively high cost of the adopted encoder.

[0034] To overcome the above technical problems, this embodiment provides a motor, which includes a stator assembly 2, a rotor assembly 1, a bushing 3, a bearing 4, and an encoder 5. The stator assembly 2 includes a housing 21, and the housing 21 includes a rear end cover 213; the rotor assembly 1 is installed inside the stator assembly 2; the rotor assembly 1 includes a rotating shaft 11; the bushing 3 is fixed to the rear end cover 213; the bearing 4 includes a first bearing ring 41 and a second bearing ring 42 that can rotate relative to each other. The first bearing ring 41 is fixedly connected to the rear end of the rotating shaft 11, and the second bearing ring 42 is fixedly connected to the bushing 3. The radial runout of the rear end of the rotating shaft 11 during rotation is restricted by the support of the bushing 3 and the bearing 4; the encoder 5 includes a coding fixing member 52 and a coding rotating member 51. The coding fixing member 52 is fixed to the bushing 3, and the coding rotating member 51 is fixed to the rear end of the rotating shaft 11.

[0035] Referring to Figure 1 , the housing 21 of the stator assembly 2 further includes a main housing 211 and a front end cover 212. The main housing 211 has a cylindrical structure, and its interior has a space capable of accommodating structures such as a stator core 22, coils, and a rotor core 12. The front end cover 212 and the rear end cover 213 are respectively disposed at the front and rear ends of the main housing 211 to form a closure. In addition to the rotating shaft 11, the rotor assembly 1 further includes a rotor core 12 and a rotor connecting member 13. The rotor core 12 is installed on the inner circumference of the stator core, the rotating shaft 11 is fixed inside the rotor core 12, and the front end of the rotating shaft 11 passes through the front end cover 212 and extends out to connect the rotor connecting member 13.

[0036] In order to miniaturize the size of the encoder 5 in this embodiment, it is installed at the rear side of the motor. This area is not affected by the rotating shaft 11 and the rotor connecting member 13. Therefore, there is no need to make a large through hole in the center of the encoder 5 for avoidance, thereby realizing the miniaturization of the encoder 5.

[0037] The output end of the motor is at the front end of the rotating shaft 11. Therefore, traditional motors only install a support bearing 4 at the front end of the motor to solve the problem of large radial runout during the operation of the rotating shaft 11. Therefore, the detection accuracy of the encoder 5 installed at the front end of the motor can be guaranteed. However, since there is a lack of stable support at the rear end of the rotating shaft 11, there will be a large radial runout at the rear end during the rotation of the rotating shaft 11. If the encoder 5 is directly installed at the rear end of the motor, it will seriously affect the accuracy of the encoder 5. To further solve this problem, this solution provides a bearing 4 and a bushing 3. The bushing 3 is fixed to the rear end cover 213, and the bearing 4 is installed between the bushing 3 and the rear end of the rotating shaft 11. By using the support provided by the bushing 3 and the bearing 4, the problem of large runout at the rear end during the rotation of the rotating shaft 11 can be effectively solved. At this time, the coding rotating member 51 and the coding fixing member 52 are respectively installed on the rotating shaft 11 and the bushing 3, which can ensure the high-precision operation of the encoder 5.

[0038] It should be noted that in this solution, the bushing 3 and the bearing 4 are used to limit the radial runout of the rear end of the rotating shaft 11, rather than ensuring absolute zero runout when the rear end of the rotating shaft 11 rotates. As long as the runout of the rear end of the rotating shaft 11 is controlled within the actual allowable error range and can meet the detection accuracy requirements of the motor application operation, it is sufficient.

[0039] In summary, for a motor based on this embodiment, the bushing 3 and the bearing 4 are installed on the rear end cover 213 of the motor. The bearing 4 is fixedly connected to the rotating shaft 11, and the support of the bushing 3 and the bearing 4 is used to limit the radial runout of the rear end of the rotating shaft 11, ensuring the stability of the rotation of the rear end of the rotating shaft 11; on the basis of ensuring the stability of the rotation of the rear end of the rotating shaft 11, the coding rotating part 51 of the encoder 5 is installed at the rear end of the rotating shaft 11, and the coding fixing part 52 is installed on the bushing 3 to realize the use function of the encoder 5. In this solution, since the coding rotating part 51 is installed at the rear end of the rotating shaft 11, compared with the traditional solution of installing the rotor connecting part 13 at the front end, there is no need to make a large through-hole radial avoidance in the middle of the encoder 5 rotating part installed at the rear end of the rotating shaft 11, and the encoder 5 fixing part installed on the bushing 3 will not interfere with the rotating shaft 11, so there is no need to make an avoidance. Therefore, based on this solution, the radial dimension of the encoder 5 can be greatly reduced, and the effect of reducing the use cost of the encoder 5 can be achieved.

[0040] In one embodiment, a plurality of positioning threaded holes are provided on the rear end cover 213, and corresponding through holes are provided on the bushing 3. The locking screw passes through the through hole and is threadedly connected to the positioning threaded hole to fix the bushing 3 on the rear end cover 213; wherein, the locking screw is in clearance fit with the through hole.

[0041] By using the locking screw to fix the bushing 3 on the rear end cover 213, it has the advantages of convenient installation and good reliability.

[0042] Importantly, there is a gap between the through hole and the locking screw in this solution, which can facilitate the adjustment of the runout of the rear end of the rotating shaft 11 to meet the accuracy requirements during the motor assembly process. Specifically, there is a gap between the locking screw and the through hole, so when the locking screw is not fully tightened, the bushing 3 can still move and fine-tune relative to the rear end cover 213 and the locking screw. The specific assembly and debugging process is as follows:

[0043] I. Preliminary assembly:

[0044] First, correctly assemble the bearing 4 and the bushing 3 to the rear end of the rotating shaft 11;

[0045] Then, rotate the bushing 3 to a position where the through hole is aligned with the positioning threaded hole on the rear end cover 213, insert the locking screw and screw it in to a certain depth for preliminary locking. At this time, the gap between the locking screw and the through hole allows the bushing 3 to be finely adjusted.

[0046] II. Detection and Debugging:

[0047] Fix the jump meter base on the rear end cover 213 or other stable positions to ensure accurate measurement of the jump meter. Press the jump meter needle against the side surface of the bushing 3 so as to capture the radial runout of the bushing 3 when it rotates with the rotating shaft 11.

[0048] Rotate the rotating shaft 11 and observe the data of the jump meter. If there is radial runout in the rotating shaft 11, it will be transmitted to the jump meter needle through the bearing 4 and the bushing 3.

[0049] According to the data of the jump meter, gently tap the bushing 3 with appropriate tools (such as a rubber hammer or a special adjustment tool) to make it move in the centering direction. It is necessary to perform runout detection and debugging from multiple different radial directions of the bushing 3 to ensure that the runout of the rotating shaft 11 in all directions is effectively controlled.

[0050] III. Final Locking:

[0051] After completing the runout debugging work, tighten the locking screw to the specified torque value. At this time, the bushing 3 is firmly fixed on the rear end cover 213, thereby maintaining the stability of the operation of the rotating shaft 11.

[0052] IV. Installation of the Encoder 5:

[0053] Install the coding rotating part 51 and the coding fixing part 52 respectively.

[0054] In one embodiment, the bushing 3 protrudes from the outer surface of the rear end cover 213 to provide a contact point for the runout test work.

[0055] Since the bushing 3 protrudes from the rear end cover 213, the tester can directly press the jump meter needle against the side surface of the bushing 3 without having to find other indirect contact points, which not only saves time but also reduces the test error caused by inaccurate contact points.

[0056] In one embodiment, the bushing 3 includes a fixing plate 31 and a connecting convex ring 32 protruding from the surface of the fixing plate 31. There is a through hole on the rear end cover 213 that has a clearance fit with the connecting convex ring 32. The fixing plate 31 is fixed on the outer surface of the rear end cover 213, and the connecting convex ring 32 extends into the through hole to be fixedly connected with the second bearing ring 42.

[0057] The design of the bushing 3 includes a fixing plate 31 and a connecting convex ring 32 protruding from the surface of the fixing plate 31. The fixing plate 31 realizes the firm connection between the bushing 3 and the rear end cover 213, and the side surface of the fixing plate 31 can provide a contact point for the jump meter needle during the runout debugging work; the connecting convex ring 32 is fixedly connected with the second bearing ring 42 on the rotating shaft 11, thereby ensuring the stability and accuracy of the rotating shaft 11 during rotation.

[0058] In one embodiment, referring to Figure 2 , the bearing 4 is an angular contact bearing 4. An outer shoulder 111 is provided on the side wall of the rotating shaft 11, and an inner shoulder 33 is provided on the inner wall of the connecting convex ring 32. The first bearing ring 41 is sleeved outside the rotating shaft 11 and contacts the outer shoulder 111, and the second bearing ring 42 is embedded and installed inside the connecting convex ring 32 and contacts the inner shoulder 33. The axial movement of the bearing 4 is restricted by the outer shoulder 111 and the inner shoulder 33.

[0059] The angular contact bearing 4 is a bearing 4 that can withstand combined radial and axial loads. There is an inclined contact angle between the inner and outer ring raceways of it, which enables the bearing 4 to withstand a certain axial load while bearing a radial load. Through the mutual cooperation of the outer shoulder 111 and the inner shoulder 33, the axial movement of the bearing 4 is effectively restricted, thus ensuring the stability of the rotating shaft 11.

[0060] Optionally, an installation hole is provided at the center of the fixing plate 31. The coding rotating part 51 is fixed to the end face of the rotating shaft 11 through the installation hole, and the coding fixing part 52 is fixed to the fixing plate 31.

[0061] Providing an installation hole at the center of the fixing plate 31 provides sufficient space for the installation of the coding rotating part 51, enabling the coding rotating part 51 to be directly fixed to the end face of the rotating shaft 11. At this time, there is no need to make any avoidance at the center of the coding rotating part 51, so the miniaturization of the coding rotating part 51 can be achieved to the greatest extent.

[0062] In another embodiment, referring to Figure 4 , the bearing 4 is a deep groove ball bearing 4. An outer shoulder 111 is provided on the side wall of the rotating shaft 11, and a bearing gland 112 is installed on the end face of the rotating shaft 11. The first bearing ring 41 is sleeved outside the rotating shaft 11, and the two end faces of the first bearing ring 41 respectively abut against the outer shoulder 111 and the bearing gland 112. The axial movement of the bearing 4 is restricted by the outer shoulder 111 and the bearing gland 112.

[0063] Through the mutual cooperation of the outer shoulder 111 and the bearing gland 112, double restriction on the axial movement of the bearing 4 is achieved. One end face of the first bearing ring 41 abuts against the outer shoulder 111, and the other end face abuts against the bearing gland 112. This double restriction ensures that the bearing 4 will not move due to axial force during operation, improving the reliability and accuracy of the rotation of the rotating shaft 11.

[0064] Optionally, an installation hole is provided at the center of the fixed plate 31. The coding rotating member 51 is fixed to the end face of the bearing gland 112 through the installation hole, and the coding fixing member 52 is fixed to the fixed plate 31.

[0065] Similarly, an installation hole is provided at the center of the fixed plate 31 to provide sufficient space for the installation of the coding rotating member 51, so that the coding rotating member 51 can be directly fixed to the end face of the bearing gland 112. At this time, no avoidance is required at the center of the coding rotating member 51, so the miniaturization of the coding rotating member 51 can be achieved to the greatest extent.

[0066] In one embodiment, a counterbore 34 is provided on the side of the fixed plate 31 facing away from the rotating shaft 11 and is circumferentially arranged around the installation hole. The coding fixing member 52 is embedded and fixed in the counterbore 34.

[0067] Specifically, the outer edge of the coding fixing member 52 is stuck in the counterbore 34 to cooperate with the coding rotating member 51 in the installation hole. The counterbore 34 provides an accurate positioning and fixing space for the coding fixing member 52. The coding fixing member 52 can be accurately embedded in the counterbore 34. This embedded fixing method not only enhances the stability of the coding fixing member 52 but also reduces the errors caused by loosening or misalignment.

[0068] In one embodiment, the rear end cover 213 is made of an aluminum alloy structure, and the bushing 3 is made of a cast iron structure.

[0069] Aluminum alloy has a relatively low density. Therefore, using aluminum alloy to manufacture the rear end cover 213 can significantly reduce the weight of the entire device. Cast iron has high strength and wear resistance, which is beneficial to ensuring the working accuracy of the encoder 5. In the description of this article, it should be understood that the terms "upper", "lower", "left", "right", etc., are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to this application. In addition, the terms "first", "second" are only used for distinction in description and have no special meaning.

[0070] In the description of this specification, the description referring to terms such as "one embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0071] In addition, it should be understood that although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0072] The technical principles of the present application are described above in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanations herein, those skilled in the art can think of other specific implementation methods of the present application without creative work, and these methods will fall within the scope of protection of the present application.

Claims

1. A motor, characterized in that: include: A stator assembly (2) comprises a housing (21), wherein the housing (21) comprises a rear end cover (213); A rotor assembly (1) is installed in the stator assembly (2); the rotor assembly (1) comprises a rotating shaft (11); A bushing (3) fixed on the rear end cover (213); The bearing (4) comprises a first bearing ring (41) and a second bearing ring (42) which are relatively rotatable, wherein the first bearing ring (41) is fixedly connected to the rear end of the rotating shaft (11), and the second bearing ring (42) is fixedly connected to the bushing (3), and the radial runout of the rear end of the rotating shaft (11) during the rotation process is limited by the support of the bushing (3) and the bearing (4); The encoder (5) comprises an encoding fixed component (52) and an encoding rotating component (51), wherein the encoding fixed component (52) is fixed to the bushing (3), and the encoding rotating component (51) is fixed to the rear end of the rotating shaft (11).

2. The motor according to claim 1, characterized in that The rear end cover (213) is provided with a plurality of positioning threaded holes, and the bushing (3) is correspondingly provided with through holes, and a locking screw passes through the through holes and is threadedly connected to the positioning threaded holes, so as to fix the bushing (3) to the rear end cover (213); wherein the locking screw is in clearance with the through holes.

3. The motor according to claim 2, characterized in that The bushing (3) protrudes from the outer surface of the rear end cover (213) to provide a contact point for the runout test.

4. The motor according to claim 3, characterized in that The bushing (3) comprises a fixing plate (31) and a connecting protruding ring (32) protruding from the surface of the fixing plate (31); the rear end cover (213) is provided with a through hole which is clearance-matched with the connecting protruding ring (32); the fixing plate (31) is fixed to the outer surface of the rear end cover (213); the connecting protruding ring (32) extends into the through hole to be fixedly connected with the second bearing ring (42).

5. The motor according to claim 4, characterized in that The bearing (4) is an angular contact bearing (4), the side wall of the rotating shaft (11) is provided with an outer shoulder (111), the inner wall of the connecting convex ring (32) is provided with an inner shoulder (33), the first bearing ring (41) is sleeved outside the rotating shaft (11) and contacts the outer shoulder (111), the second bearing ring (42) is embedded in the connecting convex ring (32) and contacts the inner shoulder (33), and the axial movement of the bearing (4) is limited by the outer shoulder (111) and the inner shoulder (33).

6. The motor according to claim 5, characterized in that A mounting hole is provided at the center of the fixing plate (31), the encoding rotating member (51) is fixed to the end surface of the rotating shaft (11) through the mounting hole, and the encoding fixing member (52) is fixed to the fixing plate (31).

7. The motor according to claim 4, characterized in that The bearing (4) is a deep groove ball bearing (4), the side wall of the rotating shaft (11) is provided with an outer shoulder (111), the end face of the rotating shaft (11) is provided with a bearing cover (112), the first bearing ring (41) is sleeved outside the rotating shaft (11), and the two end faces of the first bearing ring (41) respectively abut against the outer shoulder (111) and the bearing cover (112), and the axial movement of the bearing (4) is limited by the outer shoulder (111) and the bearing cover (112).

8. The motor according to claim 7, characterized in that A mounting hole is provided at the center of the fixing plate (31), the encoding rotating member (51) is fixed to the end surface of the bearing pressure cover (112) through the mounting hole, and the encoding fixing member (52) is fixed to the fixing plate (31).

9. The motor according to claim 6 or 8, characterized in that: A recessed groove (34) circumferentially arranged around the mounting hole is provided on a side of the fixing plate (31) facing away from the rotating shaft (11), and the coding fixing piece (52) is embedded and fixed in the recessed groove (34).

10. The motor according to claim 1, characterized in that The rear end cover (213) is an aluminum alloy structure, and the bushing (3) is a cast iron structure.

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