Electric motor and robot having the same

Abstract

The application provides a motor and a robot with the motor, wherein the motor comprises a brake, a motor rotating shaft and a first bearing sleeved on the motor rotating shaft; the brake comprises a brake stator core and a brake winding; the brake stator core is provided with a groove around the brake stator core; the brake winding is arranged in the groove; the brake stator core is further provided with a bearing chamber; and the first bearing is arranged in the bearing chamber. According to the application, the bearing chamber originally arranged on the rear end cover is arranged on the brake stator core, so that the installation position of the first bearing is transferred from the rear end cover to the brake stator core; after the first bearing is embedded in the brake stator core, the rear end cover does not need to be provided with the bearing chamber to install the first bearing, so that the rear end cover can be made thinner, thereby shortening the axial length of the motor and improving the power density of the motor.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically relating to an electric motor and a robot having the same. Background Technology

[0002] Industrial robot applications demand high performance, high power density, and miniaturization from permanent magnet servo motors. High power density and miniaturization effectively reduce the motor's installation space requirements, resulting in smaller, lighter, more flexible, and easier-to-control robot structures, significantly improving application compatibility. The operating conditions of industrial robots require servo motors to have built-in brakes. A common brake installation structure within the servo motor is as follows... Figure 4 As shown, the brake is mounted on the rear end cover of the motor by three circumferentially distributed fastening screws. The general-purpose power failure brake and the motor section behind it account for about 46.9% of the overall length of the machine, which occupies a large space. Therefore, shortening the axial length of this part is a breakthrough to improve the power density of the motor and shorten the length of the motor.

[0003] Analysis of the installation structure revealed the following two problems:

[0004] ① The structure and size of the brake are fixed, and there is a large gap between the outer diameter of the brake and the inner wall of the rear cover. This space is not effectively utilized and is not conducive to the heat dissipation of the brake.

[0005] ② The brake is locked to the rear end cover by fastening screws. The brake stator core needs to be provided with mounting through holes, which limits the diameter of the brake winding; the rear end cover needs to be provided with mounting threaded holes, which limits the wall thickness of the rear end cover.

[0006] This solution focuses on tackling the above two problems with the goal of reducing brake thickness, conducting in-depth research and analysis of general-purpose power-off brakes, and innovatively proposing this solution. Furthermore, in the entire permanent magnet servo motor structure, the temperature rise limit mainly involves two aspects: stator winding temperature rise and encoder temperature rise. Research and testing analysis revealed that the temperature rise of the stator winding in traditional servo motors still has a 30K margin, while the encoder temperature rise has exceeded the limit, indicating that the encoder is the weakest link in the servo motor's temperature rise and a major bottleneck for further improving the power density of the servo motor. To address the requirement for a lower encoder temperature rise limit, this application also makes improvements in this area. Summary of the Invention

[0007] Therefore, the present invention provides a motor that can solve the technical problem that the rear half of the existing motor accounts for a large proportion of the overall length, resulting in a large motor size and affecting the power density of the motor.

[0008] To solve the above problems, the present invention provides an electric motor, including: a brake, a motor shaft, and a first bearing mounted on the motor shaft. The brake includes a brake stator core and a brake winding. The brake stator core has a groove that surrounds itself once. The brake winding is disposed in the groove. The brake stator core also has a bearing chamber. The first bearing is installed in the bearing chamber.

[0009] In some implementations, the bearing housing is located inside the groove along the radial direction of the brake stator core.

[0010] In some embodiments, the motor further includes a housing, and the brake stator core is assembled at one end of the housing having an opening.

[0011] In some embodiments, the brake stator core has an outer surface that is in contact with the external air of the motor.

[0012] In some embodiments, a motor stator assembly is disposed within the space enclosed by the brake stator core and the housing, and the brake stator core has a first end face facing the motor stator assembly, and a clearance groove is formed on the first end face around the brake stator core.

[0013] In some embodiments, the clearance groove is provided with a plurality of reinforcing ribs, each reinforcing rib being distributed at intervals along the circumference of the clearance groove. The two ends of the reinforcing ribs are respectively connected to the first sidewall and the second sidewall of the clearance groove. Along the radial direction of the brake stator core, the second sidewall is located outside the first sidewall.

[0014] In some embodiments, the brake stator core further has a second end face facing away from the motor stator assembly, the groove is formed on the second end face, the bearing chamber is formed on the first end face, and the bearing chamber is located inside the clearance groove along the radial direction of the brake stator core.

[0015] In some embodiments, the brake further includes a friction pad and a brake hub, the friction pad and the brake hub being sequentially disposed on the side of the brake stator core facing away from the motor stator assembly, and the friction pad being fixed on the brake hub.

[0016] In some embodiments, a rear end cover is assembled on the side of the brake stator core facing away from the housing, the friction pads and brake hub are both located within the space enclosed by the rear end cover and the brake stator core, an encoder is provided on the side of the rear end cover facing away from the brake stator core, and the rear end cover is made of heat-insulating material.

[0017] In some embodiments, the housing is provided with a wire outlet, and the brake stator core is provided with a through wire hole. The lead wire of the brake winding passes directly through the through wire hole and is led out from the wire outlet together with the lead wire of the motor stator assembly.

[0018] The present invention also provides a robot, including the motor described above.

[0019] The present invention provides an electric motor and a robot having the same, which have the following beneficial effects:

[0020] This application constructs the bearing housing, originally located in the rear end cover, onto the brake stator core, thereby transferring the installation position of the first bearing from the rear end cover to the brake stator core. After the first bearing is embedded in the brake stator core, the rear end cover can be made thinner because it does not need to construct a bearing housing to install the first bearing. This shortens the axial length of the motor and increases the power density of the motor. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the motor according to an embodiment of the present invention;

[0023] Figure 2 This is a front view of the first end cover of the motor according to an embodiment of the present invention;

[0024] Figure 3 This is a reverse view of the first end cover of the motor according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of an existing motor.

[0026] The reference numerals in the attached figures are as follows:

[0027] 1. Motor shaft; 2. First bearing; 3. Brake winding; 4. Motor stator assembly; 5. Housing; 6. Rear end cover; 7. Clearance groove; 8. Reinforcing rib; 9. Mounting hole; 10. Armature; 11. Guide post; 12. Friction plate; 13. Brake hub; 14. Cable outlet; 15. Cable through hole; 16. Encoder; 17. Pin hole; 18. Hub fastening screw; 19. Rotor assembly; 20. Front bearing; 21. Brake fastening screw; 22. Brake stator core. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0031] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0032] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0033] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0034] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0035] See also Figures 1 to 4 As shown, according to an embodiment of the present invention, an electric motor is provided, including: a brake, a motor shaft 1, and a first bearing 2 mounted on the motor shaft 1. The brake includes a brake stator core 22 and a brake winding 3. The brake stator core 22 has a groove that surrounds itself once. The brake winding 3 is disposed in the groove. The brake stator core 22 also has a bearing chamber. The first bearing 2 is installed in the bearing chamber.

[0036] In this technical solution, the bearing housing, originally located in the rear end cover 6, is constructed on the brake stator core 22. This allows the mounting position of the first bearing 2 to be transferred from the rear end cover 6 to the brake stator core 22. After the first bearing 2 is embedded in the brake stator core 22, the rear end cover 6 can be made thinner because it no longer needs to construct a bearing housing to install the first bearing 2. This shortens the axial length of the motor and increases the power density of the motor. The first bearing 2 is the rear bearing of the motor.

[0037] Specifically, along the radial direction of the brake stator core 22, the bearing housing is located inside the groove. This causes the bearing housing and the groove to be staggered along the radial direction of the brake stator core 22, and further causes the bearing housing and the groove to overlap along the axial direction of the brake stator core 22, which can further reduce the axial length of the motor.

[0038] See also Figure 1 As shown, the motor also includes a housing 5, with the brake stator core 22 assembled at one end of the housing 5 having an opening. In this embodiment, because the brake stator core 22 is directly assembled onto the housing 5, the series of structures that involve constructing mounting threaded holes on the rear end cover 6 and then fixing the brake stator core 22 and the rear end cover 6 together using brake fastening screws 21 can be eliminated compared to the prior art. Furthermore, since the rear end cover 6 does not need to support the brake stator core 22, the pressure on it is reduced, allowing the rear end cover 6 to be made even thinner.

[0039] See also Figure 1 As shown, compared with the prior art, since the brake stator core 22 of this application does not need to be fixed on the rear end cover 6, the radial dimension of the brake stator core 22 can be larger. This makes the brake stator core 22 have an outer surface that is in contact with the external air of the motor, thereby improving the heat dissipation effect of the brake stator core 22.

[0040] See also Figure 1 As shown, a motor stator assembly 4 is provided in the space enclosed by the brake stator core 22 and the housing 5. The brake stator core 22 has a first end face facing the motor stator assembly 4, and a clearance groove 7 is constructed on the first end face around the brake stator core 22.

[0041] In this embodiment, the side of the motor stator assembly 4 facing the brake stator core 22 will have a circuit board and lead wires. By constructing the avoidance groove 7, the circuit board and lead wires can be avoided when installing the brake stator core 22. At the same time, because the circuit board and lead wires can be avoided, the brake stator core 22 can be inserted deeper into the direction of the motor stator assembly 4, which can further shorten the overall length of the machine.

[0042] See also Figure 2 As shown, a plurality of reinforcing ribs 8 are provided in the clearance groove 7. Each reinforcing rib 8 is distributed at intervals along the circumference of the clearance groove 7. The two ends of the reinforcing rib 8 are respectively connected to the first side wall and the second side wall of the clearance groove 7. Along the radial direction of the brake stator core 22, the second side wall is located outside the first side wall.

[0043] In this technical solution, the grooves, bearing chambers, and clearance grooves 7 constructed on the brake stator core 22 have a certain impact on the structural strength of the brake stator core 22. By setting multiple reinforcing ribs 8, the structural strength of the brake stator core 22 can be enhanced, thereby compensating for the weakening of the structural strength of the brake stator core 22. Each reinforcing rib 8 can be integrally formed with the brake stator core 22, or it can be connected separately within the clearance groove 7.

[0044] In one specific implementation, the brake stator core 22 also has a second end face facing away from the motor stator assembly 4, a groove is constructed on the second end face, and a bearing chamber is constructed on the first end face. Along the radial direction of the brake stator core 22, the bearing chamber is located inside the clearance groove 7.

[0045] In this technical solution, if the groove and bearing chamber are constructed on the same end face, a thin-walled annular structure extending circumferentially along the brake stator core 22 will appear between the groove and the bearing chamber. Obviously, the thin-walled structure is relatively fragile and will seriously affect the structural strength of the brake stator core 22. However, when the groove and bearing chamber are constructed on two end faces of the brake stator core 22 with different orientations, the groove and bearing chamber can be staggered, thereby avoiding the formation of a large-area thin-walled annular structure.

[0046] Specifically, multiple mounting holes 9 are also constructed on the second end face. Each mounting hole 9 is distributed circumferentially along the brake stator core 22. Along the radial direction of the brake stator core 22, each mounting hole 9 is located outside the groove. Each mounting hole 9 is equipped with an elastic component. An armature 10 is provided on the side of the brake stator core 22 facing away from the motor stator assembly 4. The end of each elastic component facing the armature 10 is connected to the armature 10.

[0047] In this embodiment, when the brake winding 3 is energized, the brake stator core 22 generates electromagnetic force, thereby attracting the armature 10 and combining it with the brake stator core 22, and the elastic component is in a compressed state; when the brake winding 3 is de-energized, the electromagnetic force disappears, and under the elastic force of the elastic component, the armature 10 and the brake stator core 22 separate, and the elastic component returns to its initial state. Preferably, the elastic component is a torque spring.

[0048] See also Figure 1As shown, a guide post 11 is provided on the second end face. Along the radial direction of the brake stator core 22, the guide post 11 is located outside the groove. A guide groove is constructed on the armature 10. The guide post 11 is inserted into the guide groove and can slide relative to the guide groove.

[0049] In this technical solution, the cooperative arrangement of the guide post 11 and the guide groove can restrict the armature 10 from rotating circumferentially, so that the armature 10 can only move relative to the brake stator core 22 axially, and the armature 10 is more stable during movement. The guide post 11 can be integrally formed on the brake stator core 22; or it can have a pin hole 17 constructed on its second end face, with the guide post 11 inserted into the pin hole 17 by an interference fit.

[0050] In one specific implementation, the brake also includes a friction pad 12 and a brake hub 13. The friction pad 12 and the brake hub 13 are sequentially arranged on the side of the armature 10 facing away from the brake stator core 22, and the friction pad 12 is fixed on the brake hub 13.

[0051] In this embodiment, the friction plate 12 is glued to the brake hub 13, changing the traditional double-sided friction braking to single-sided friction braking. This also eliminates the need for mounting screws on the flat plate, reducing the brake's thickness. Two 90° hub fastening screws 18 rigidly connect the brake hub 13 to the rotor assembly 19's shaft. This design avoids the common problem in conventional brakes where, under energized conditions, the armature 10 is attracted to the stator core 22, leaving the friction plate 12 axially free between the armature 10 and the flat plate. This prevents the friction plate 12 from randomly impacting the armature 10 and the flat plate during rotor assembly 19 rotation, thus reducing impact and noise and extending the friction plate's lifespan.

[0052] Specifically, a rear end cover 6 is assembled on the side of the brake stator core 22 facing away from the housing 5. The armature 10, friction plate 12 and brake hub 13 are all located in the space enclosed by the rear end cover 6 and the brake stator core 22. An encoder 16 is provided on the side of the rear end cover 6 facing away from the brake stator core 22. The rear end cover 6 is made of heat insulation material.

[0053] Preferably, the rear cover 6 is made of DuPont Rynite FR530 BK507, a bakelite material with low thermal conductivity. Compared with the thermal conductivity of traditional aluminum (200 W / m·K) and bakelite (0.12 W / m·K), its thermal conductivity is significantly reduced. This can effectively reduce the heat generated by the stator winding and brake winding 3 from being transferred to the encoder 16, ensuring that both the motor winding and the encoder 16 are within a reasonable operating temperature range. This optimizes the axial heat transfer path of the motor and solves the problem of the low temperature rise limit requirement of the encoder 16.

[0054] It should be noted that the rear end cover 6 of this application does not need to install the rear bearing 2 and the fixed brake stator core 22. Therefore, the rear end cover 6 can be made thinner. With the other measures mentioned above, the overall length of the motor is shortened by 15.4mm, which meets the design target requirements and effectively improves the power density of the motor. This ensures that the temperature rise index of the motor meets the design requirements after high power density and miniaturization design.

[0055] See also Figure 1 As shown, the housing 5 has a wire outlet 14, and the brake stator core 22 has a through wire hole 15. The lead wire of the brake winding 3 passes directly through the wire hole 15 and is led out from the wire outlet 14 together with the lead wire of the motor stator assembly 4.

[0056] In the existing motor, the brake stator core 22 is fixed to the rear end cover 6. The distance between the brake winding 3 and the outlet 14 is relatively far, requiring a slot to be cut in the rear end cover 6 to facilitate the welding of the brake winding 3's lead wires and power wires. The welded wires then need to return to the motor and be led out from the outlet 14, which is quite cumbersome. Furthermore, a cover body is needed to seal and waterproof the slotted area on the rear end cover 6, and this cover body also needs to accommodate any excess welded wire. However, with the solution of this application, since the brake stator core 22 is very close to the outlet 14, it is not necessary to weld the brake winding 3's lead wires and power wires. Only a wire-passing hole 15 needs to be constructed on the brake stator core 22, allowing the brake winding 3's lead wires to pass directly through the wire-passing hole 15 and be led out from the outlet 14 together with the motor stator assembly 4's lead wires. This avoids the need for a slot in the rear end cover 6, resulting in better waterproofing of the motor. Meanwhile, if there is excess wire in the lead wire of the brake winding 3, it can be stored inside the wire hole 15.

[0057] The following are some specific parameters of the motor used in this application:

[0058] Calculation of rated braking torque M

[0059] This study uses a 400W motor as an example, with a rated speed of 3000 r / min and a rated torque of 1.27 Nm. The requirements for the brake are: static friction torque ≥ 1.3 Nm. Assuming a braking safety factor of 1.5, the design requirement for the static friction torque of the brake in this scheme is determined to be: M ≥ 1.95 Nm.

[0060] Calculation of effective radius Re of braking torque

[0061] Taking into account the internal space of the motor and the requirements of the brake structure, and comprehensively considering the inertia and utilization rate of the friction plate 12, the effective radius Re of the brake hub 13 is set to 19.25mm.

[0062] Calculation of friction braking force F

[0063] The friction plate 12 is bonded and fixed to the brake hub 13. The braking force F is generated by the one-sided friction between the friction plate 12 and the armature 10. The friction plate 12 is made of asbestos-free resin-based glass fiber material with a coefficient of friction of 0.348. Therefore, the friction braking force F = M / Re × μ = 1.95 / 0.01925 / 0.348 = 291.1 N.

[0064] Torque spring pressure Fd calculation

[0065] The torque springs are arranged axially on the stator core 22 of the brake. Considering the structural strength requirements, the torque springs are set to be evenly distributed on a circle with a diameter D = 54 mm. According to the force balance equation: Fd × π × D = F × π × 2Re, Fd = 207.5 N is calculated.

[0066] If six torque springs are evenly distributed on the circumference, each spring needs to provide a spring force of 34.6N.

[0067] The present invention also provides a robot, including the motor described above.

[0068] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. An electric motor, characterized in that, The device includes a brake, a motor shaft (1), and a first bearing (2) mounted on the motor shaft (1). The brake includes a brake stator core (22) and a brake winding (3). The brake stator core (22) has a groove that wraps around itself once. The brake winding (3) is disposed in the groove. The brake stator core (22) also has a bearing chamber. The first bearing (2) is installed in the bearing chamber. Along the radial direction of the brake stator core (22), the bearing chamber is located inside the groove, and the bearing chamber and the groove have overlapping portions along the axial direction of the brake stator core (22); It also includes a housing (5), the brake stator core (22) is assembled at one end of the housing (5) with an opening, and a motor stator assembly (4) is provided in the space enclosed by the brake stator core (22) and the housing (5). The brake stator core (22) has a first end face facing the motor stator assembly (4), and a clearance groove (7) is constructed on the first end face around the brake stator core (22). A plurality of reinforcing ribs (8) are provided in the clearance groove (7).

2. The motor according to claim 1, characterized in that, The brake stator core (22) has an outer surface that is in contact with the air outside the motor.

3. The motor according to claim 1, characterized in that, Each of the reinforcing ribs (8) is distributed circumferentially along the clearance groove (7). The two ends of the reinforcing ribs (8) are respectively connected to the first side wall and the second side wall of the clearance groove (7). Along the radial direction of the brake stator core (22), the second side wall is located outside the first side wall.

4. The motor according to claim 1, characterized in that, The brake stator core (22) also has a second end face facing away from the motor stator assembly (4), the groove is constructed on the second end face, the bearing chamber is constructed on the first end face, and along the radial direction of the brake stator core (22), the bearing chamber is located inside the clearance groove (7).

5. The motor according to claim 1, characterized in that, The brake also includes a friction plate (12) and a brake hub (13). The friction plate (12) and the brake hub (13) are arranged sequentially on the side of the brake stator core (22) facing away from the motor stator assembly (4). The friction plate (12) is fixed on the brake hub (13).

6. The motor according to claim 5, characterized in that, The brake stator core (22) is equipped with a rear end cover (6) on the side facing away from the housing (5). The friction plate (12) and the brake hub (13) are both located in the space enclosed by the rear end cover (6) and the brake stator core (22). An encoder (16) is provided on the side of the rear end cover (6) facing away from the brake stator core (22). The rear end cover (6) is made of heat-insulating material.

7. The motor according to any one of claims 1 to 6, characterized in that, The housing (5) has a wire outlet (14), and the brake stator core (22) has a through wire hole (15). The lead wire of the brake winding (3) passes directly through the through wire hole (15) and is led out from the wire outlet (14) together with the lead wire of the motor stator assembly (4).

8. A robot, characterized in that, Includes the motor as described in any one of claims 1 to 7.

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