CN113572279A

CN113572279A - Motor stator module, motor and electric tool

Info

Publication number: CN113572279A
Application number: CN202010355733.2A
Authority: CN
Inventors: 张自立; 方承志; 王鹏
Original assignee: Bosch Power Tools China Co Ltd
Current assignee: Bosch Power Tools China Co Ltd
Priority date: 2020-04-29
Filing date: 2020-04-29
Publication date: 2021-10-29
Also published as: DE212021000371U1; WO2021218996A1; BR112022021888A2

Abstract

The application provides a motor stator subassembly, motor and electric tool. This motor stator subassembly includes: a stator core having a yoke portion and a plurality of teeth portions provided on the yoke portion at intervals in a circumferential direction, each of the teeth portions extending in a radial direction; a stator winding including windings wound around the respective teeth; and a plurality of rubber covers configured to cover the windings on the teeth, respectively; wherein, each rubber cover shell is provided with stator slots which are spaced along the circumferential direction of the stator core. According to the motor stator subassembly of this application, improved leakproofness and the fixity to each tooth portion and stator winding, had the heat dispersion of improvement, reform transform with low costs and the suitability is strong.

Description

Motor stator module, motor and electric tool

Technical Field

The present application relates to the field of electric motors, and more particularly, to an improved stator assembly for an electric motor and a power tool having such an electric motor.

Background

Electric machines are a widely used class of power source components in the prior art, and typically include a rotor and a stator that cooperate to generate a magnetic field and to cut the magnetic field to produce an electric current. For the motor in the field of electric tools, the common stator production process includes modes of dropping paint, coating powder and the like. For example, in order to be suitable for an electric tool working in a metal dust environment, the outer surface of the stator winding of the motor matched with the electric tool needs to be subjected to a powder coating process. Thereby preventing metal dust from damaging copper wires in the windings and further causing short circuit of the motor. For another example, in order to be suitable for an electric tool working in a strong vibration environment, the outer surface of the stator of the motor adapted to the electric tool needs to perform a paint dripping or dipping process. Therefore, the fixation of the windings is strengthened, and the short circuit of the windings caused by vibration is prevented, so that the short circuit of the motor is further caused. There are certain reliability challenges in the practical application of the aforementioned environments. In addition, in other fields, such as the field of household appliances or new energy vehicles, there is also a class of electric machines that performs an integral potting process on the stator of the electric machine, thereby making it possible to work in a humid and vibrating environment. However, such an integral potting process brings both poor heat dissipation and low power density. Therefore, to increase the power density, cooling channels may be added to the stator periphery to improve heat dissipation, which may result in additional cost.

Disclosure of Invention

In view of the above, the present application provides a motor-stator assembly, a motor, and a power tool, which effectively solve or alleviate one or more of the above problems and other problems in the prior art.

To solve at least one of the above technical problems, according to an aspect of the present application, there is provided a stator assembly of an electric machine, including: a stator core having a yoke portion and a plurality of teeth portions provided on the yoke portion at intervals in a circumferential direction, each of the teeth portions extending in a radial direction; a stator winding including windings wound around the respective teeth; and a plurality of rubber covers configured to cover the windings on the teeth, respectively; wherein each of the rubber casings has stator slots spaced apart in a circumferential direction of the stator core therebetween.

To solve at least one of the above technical problems, according to another aspect of the present application, there is provided a motor including: a rotor; and a motor stator assembly as previously described; the rotor is axially arranged in the middle of the stator assembly of the motor.

To solve at least one of the above technical problems, according to another aspect of the present application, there is provided a power tool including: an electric machine having a machine stator assembly as hereinbefore described, or an electric machine as hereinbefore described.

According to the technical scheme of the application, the winding on each tooth part is sealed through the glue housing, so that the sealing performance and the fixing performance of the winding are effectively ensured, the reliability challenge caused by metal dust and strong vibration is avoided, and the glue housing has better heat transfer performance than an air layer, so that the quick transfer of winding heat is facilitated; in addition, because of the targeted sealing, stator slots which are spaced along the circumferential direction are reserved among the rubber casings, and heat transmitted by the rubber casings can be quickly dissipated through air circulation in the stator slots, so that the improved heat dissipation performance is achieved, and the power density of the motor is not affected by poor heat dissipation. Moreover, for part of the motors, because the grooves for winding the windings are originally reserved on each tooth part, stator grooves spaced along the circumferential direction can be naturally formed in the residual space after the windings are sealed by adopting the rubber housing in the grooves, so that a new stator structure does not need to be designed, the transformation cost is low, and the applicability is strong. For a part of high-voltage multi-phase motors, according to standard requirements, the distance between adjacent windings of the stator winding should meet certain non-conductive insulation requirements, and the existence of the rubber housing can reduce or eliminate the non-conductive insulation distance, so that the non-conductive insulation distance is more in line with the electrical insulation requirements.

Drawings

The present application will be more fully understood from the detailed description given below with reference to the accompanying drawings, in which like reference numerals refer to like elements in the figures. Wherein:

FIG. 1 is a perspective view of one embodiment of a stator assembly of an electric machine in which a glue housing has not been formed; and

fig. 2 is a perspective schematic view of one embodiment of a stator assembly of an electric machine in which a glue housing has been formed.

FIG. 3 is a cross-sectional schematic view of one embodiment of a stator assembly of an electric machine in which a glue housing has been formed.

Fig. 4 is a perspective view of a glue housing formed in one embodiment of the motor stator assembly shown in fig. 2.

Fig. 5 is a cross-sectional schematic view of another embodiment of a stator assembly of an electric machine in which a glue housing has been formed.

Fig. 6 is a perspective view of a glue housing formed in one embodiment of the motor stator assembly shown in fig. 5.

Detailed Description

First, it should be noted that the stator assembly of the motor and the composition, operation principle, features and advantages of the motor according to the present application will be described below by way of example, but it should be understood that all the descriptions are given for illustrative purposes only and thus should not be construed as forming any limitation to the present application. In this document, the technical term "connected" and its derivatives cover that one component is directly connected to another component and/or indirectly connected to another component. And the use of the verb "to comprise" is herein intended to mean two or more than two, as opposed to "a" or "an".

Furthermore, to any single feature described or implicit in an embodiment or shown or implicit in the drawings, the present application still allows any combination or permutation to continue between the features (or their equivalents) without any technical impediment, thereby achieving more other embodiments of the present application that may not be directly mentioned herein.

The general structure and construction of one embodiment of a stator assembly of an electric machine according to the present application is shown in fig. 1-4, respectively, in a schematic manner from the perspective of the component parts and mounting relationships. And the general structure and construction of another embodiment of a stator assembly of an electric machine according to the present application is shown in figures 5-6, respectively, from the perspective of the component parts and mounting relationships, in a schematic manner. The technical solution of the present application will be described in detail below with reference to the above drawings.

Referring to fig. 1-4, the electric machine stator assembly 100 generally includes three components, a stator core 110, stator windings 120, and a rubberized casing 130. The stator core 110 is generally formed by stacking several ring-like silicon steel sheets having a substantially ring-shaped yoke portion 111, and an annular hollow portion is formed therein for assembling a rotor. The silicon steel sheets also have a plurality of teeth 112 provided at intervals in the circumferential direction on the yoke portion 111, and the respective teeth 112 extend in the radial direction. Winding wires 121 (e.g., copper wire) are wound around the radially extending teeth 112 to form stator windings 120 for the electric machine stator assembly 100, respectively. Subsequently, a plastic housing 130 may be formed outside the stator winding 120. Specifically, a plurality of rubber housings 130 may be arranged to cover the windings 121 on the respective teeth 112. It should be noted that, although there are a plurality of rubber casings 130 and a plurality of teeth 112 with windings 121, the application is not intended to limit the number of the two to correspond one by one. For example, in practice, a single rubber casing 130 may be used to cover a single tooth 112, a single rubber casing 130 may be used to cover a plurality of adjacent teeth 112, or a combination of the two rubber casings 130 may be used, so long as it is ensured that the teeth with the windings 121 are all covered. Further, it should be noted that, ideally, it is desirable that the glue casing 130 can hermetically cover the windings 121 on the respective teeth 112, so that the windings 121 can receive the protective effect of the sealing property and the high heat conductivity effect of the glue material, but in practice, considering various aspects such as the precision of the glue casing molding process, there may be a case where the glue casing 130 does not completely hermetically cover the windings 121 on the respective teeth 112, which still falls within the concept described herein. Next, after each of the rubber casings 130 is disposed, stator slots 140 spaced apart in the circumferential direction are provided between the adjacent rubber casings 130.

According to the technical scheme of the application, the windings 121 on the tooth parts 112 are sealed through the rubber housing 130, so that the sealing performance and the fixing performance are effectively ensured, the reliability challenge caused by metal dust and strong vibration is avoided, and the rubber housing 130 has better heat transfer performance than an air layer, so that the quick heat transfer of the windings is facilitated; in addition, because of the targeted sealing, stator slots 140 spaced along the circumferential direction are reserved between the rubber casings 130, and the heat transferred from the rubber casings 130 can be quickly dissipated through the air circulation in the stator slots 140, so that the heat dissipation performance is improved, and the power density of the motor is not affected by the poor heat dissipation. Furthermore, for some motors, since the slots for winding the windings 121 are originally left in each tooth 112, the stator slots 140 spaced apart in the circumferential direction can be formed naturally in the remaining space in the slots after the windings are sealed by the rubber housing 130, and therefore, a new stator structure does not need to be designed, the modification cost is low, and the applicability is high. For some high voltage multiphase motors, according to the standard requirement, the distance between adjacent windings 121 of the stator winding 120 should meet a certain non-conductive insulation requirement, and the presence of the rubber cover 130 can reduce or eliminate the non-conductive insulation distance, so as to meet the electrical insulation requirement.

On the basis of the foregoing embodiments, several modifications may be made to the various components of the stator assembly of the motor or their connection positions in order to obtain other or additional technical effects, as will be exemplarily described below.

For example, for each tooth 112 of such an electric machine stator assembly 100, it may be arranged to extend radially inward on the stator core 110. At this time, a tapered groove pointing to the axis for passing the nozzle when winding the winding 121 is originally left between the teeth portions 112, thereby facilitating the molding of the rubber cover 130. Furthermore, each tooth 112 may also be arranged to extend radially outward on the stator core 110, with the diverging passages formed therebetween also serving as stator slots 140 for subsequent ventilation and heat dissipation.

As another example, to ensure that the stator slots 140 provide sufficient flow area for ventilation and heat dissipation, they are configured to have sufficient radial depth. For example, the stator slots 140 may be arranged to extend radially from a first end of the tooth portion 112 near the yoke portion 111 to a second end of the tooth portion 112 facing away from the yoke portion 111, such that the portions between adjacent tooth portions 112 that are not filled by the glue casing each constitute the stator slots 140.

Optionally, as shown more clearly in fig. 3-4, each tooth 112 of the motor-stator assembly 100 may also be provided with a stop 112a at an end distal from the yoke 111. The plurality of glue cases 130 may also be configured to at least partially cover the stopper 112 a. At this time, the circumference of the teeth 112 of the rubber housing 130 having the winding is more completely covered by the rubber housing 130, thereby providing better sealability and thermal conductivity to the winding 121. On this basis, the adjacent rubber cases 130 may be connected to each other at the side of the stopper portion 112a covered by the rubber cases. This arrangement connects the first portions 130a of the plurality of rubber cases 130 for covering the windings on the teeth, respectively, through the second portions 130b for covering the stoppers 112a, so that the plurality of rubber cases 130 can be molded by one set of molds, simplifying the manufacturing process thereof; in addition, the stopper portion 112a and the circumferential wall surface of the stator core 110 together form a radial limit for the molded plastic housing 130, so that the positioning is firmer. Further, positioning grooves 112b may be further provided on both ends of the stopper portion 112a in the circumferential direction, so that the glue case 130 made of glue is formed to fill the positioning grooves 112b, thereby providing a further positioning effect thereto.

As another example, although a single glue housing 130 is schematically illustrated in fig. 4, it is merely for purposes of clearly describing the housing structure. For such a glue cover 130 of the motor stator assembly 100, the winding 121 may be completed on the stator core 110 and the stator winding 120 may be formed, and then a glue filling process may be applied to form the glue cover. Specifically, a corresponding molding die may be provided, into which a liquid paste having a thermal conductivity of not less than 0.2W/(m × K) is poured, the poured paste will flow to and fill each gap between the die and the stator assembly along the guidance of the die, for example, it will fill the gap between the windings 121 wound on the teeth, and then the setting molding and the arrangement of the glue housing 130 are completed. Alternatively, in the molding process of the rubber housing 130, the rubber housing may be formed to have a thickness uniformly surrounding the stator winding 120, that is, a glue filling process is applied according to the shape of the coil, so that the thickness of the glue layer forming the rubber housing 130 is similar at each position, and the heat dissipation of each part of the stator winding 120 is uniform, so that the temperature rise is more uniform. Meanwhile, it is difficult to prepare a proper mold to form a glue layer having a uniform thickness thereon, considering that the shape of the winding end in practical use may be influenced by various factors such as a winding type, a winding process, a slot fill factor, etc., and thus it is difficult to have a regular shape. In this case, attention may be focused on making the portion of the rubber housing 130 that axially surrounds the teeth 112 and the stator windings 120 have a uniform thickness. Because this portion already occupies a relatively large amount of surface area of the winding, a consistent and uniform temperature rise across the stator winding 120 has been achieved to a considerable extent. Also optionally, during molding of the glue housing 130, it may be formed to have a contoured outer surface, wherein the contoured outer surface has a greater surface area than if the glue housing 130 were simply formed to have a flat outer surface profile. As a specific example, a wavy surface having a plurality of curved surfaces outside, or a plurality of projections and recesses may be provided. Thereby improving heat dissipation efficiency by increasing the surface area.

As another example, for the stator slots 140 of such an electric machine stator assembly 100, they may be equal width slots or tapered width slots. Wherein, the width gradually changing groove can be used for matching the glue housing 130 with uniform thickness; and the equal-width groove enables the forming die of the glue filling process to be manufactured more easily.

Further, since the width of the stator slots 140 may be inversely proportional to the slot fill ratio of the stator core 110. Thus, with a glued casing, the performance of the motor can be affected by adjusting the slot fill ratio and the width of the stator slots 140. As an example, since the motor stator assembly 100 has the stator slots 140 for ventilation heat dissipation, heat dissipation conditions can be improved, and when the same winding 121 scheme is adopted, thinner copper wires are applied, thereby reducing slot fullness and improving the process by reducing the sectional area of the winding 121. As another example, for some motors with poor ventilation and heat dissipation effects due to lack of fans or harsh working environment, the same winding 121 scheme can be adopted by using thicker copper wires, so as to increase the slot filling ratio by increasing the cross-sectional area of the winding 121, thereby reducing heat generation.

For the motor stator assembly 100 in practical application, in order to solve the insulation problem between the winding wire and the silicon steel sheet constituting the stator core 110, an insulation element 150 is usually disposed therebetween, for example, insulation paper 152 is disposed on each wall surface of the stator core 110 in the axial direction, and insulation brackets 151 are disposed on both ends of the stator core 110 in the axial direction, thereby ensuring that the winding wire 121 does not contact with the silicon steel sheet in each direction, and further achieving the insulation purpose. In addition, because the silicon steel sheet and the winding are made of metal, the existence of the insulating paper 152 and the insulating support 151 also avoids the scratch caused by rigid friction between the two in the winding process.

Turning to fig. 5-6, another embodiment of an electric machine stator assembly 100 according to the inventive concepts of the present application is shown. Which is substantially similar in construction to the motor-stator assembly 100 described above with reference to fig. 1-4, except that the present embodiment provides a further improvement to the glue housing. Specifically, the plurality of rubber cases 130 herein are configured to be connected to each other at the axial end portion of the stator core 110 to form a rubber ring 131, thereby integrating the plurality of rubber cases 130. This arrangement allows a plurality of glue housings 130 to be formed by a set of molds, simplifying the manufacturing process.

Furthermore, the stator winding 120 usually includes a gap bridge wire connected between the windings 121 wound around the teeth 112, which also has sealing and heat dissipation requirements, but since it is located at the axial end of the stator of the motor, it is easier to contact the external environment to dissipate heat and to improve the sealing and heat dissipation effects through various processes compared to the windings mostly located in the axial inner portion of the stator, and therefore, potting is not the most economical means for achieving the sealing and heat dissipation. However, on the basis of the design of the rubber ring 131 in the idea of the present application, the specific positioning of the rubber ring 131 on the axial end portion can be adjusted to be configured to wrap the bridge wire from the axial end portion, thereby further improving the sealing performance and the heat dissipation effect of the stator winding as a whole.

Further, although not shown, embodiments of an electric machine are provided herein that include the electric machine stator assembly 100 of any of the embodiments described above, or a combination thereof. In addition, the motor further includes a rotor cooperating with the motor stator assembly 100; the rotor is inserted into the middle of the motor stator assembly 100 in the axial direction and is assembled therein. The motor with this arrangement has the corresponding technical effects of the improved motor stator assembly 100, which will not be described in detail herein. Simultaneously, this motor can also the free choice whether seal the motor air gap: for the motor used in the metal processing environment, dust can be prevented from entering by closing the air gap, and the existence of the rubber housing 130 makes the heat dissipation effect of the motor still not insufficient after the air gap is closed. For motors used in other environments, an open air gap can be selected, so that the heat dissipation of the rotor is facilitated and the open glue filling process method is conveniently applied to the motor stator assembly 100.

In addition, such a motor-stator assembly 100 has a particularly prominent effect when applied to a brushless inner-wound motor. Because the brushless inner-winding motor is provided with the teeth parts 112 extending inwards in the radial direction, and the tapered channels which are used for the wire mouths to pass through when the winding wire 121 is wound are originally reserved among the teeth parts 112 and point to the axis, the residual space of the partial channels after the winding is encapsulated by the glue cover shell 130 can naturally form the stator slots 140 which are spaced in the circumferential direction, and therefore, a new stator structure does not need to be designed, the transformation cost is low, and the applicability is strong.

Further, the motor may further include a fan. At this time, the fan is fixedly installed at the axial end of the rotor so that both can be produced, assembled or sold as an assembly. The fan may be used to drive air through the stator slots 140 of the motor stator assembly 100 described above. This arrangement allows the heat of the stator winding 120 to be quickly transferred out through the rubber cover 130 and then quickly taken away by the flowing air, thereby providing a better heat dissipation effect.

In addition, although not shown, an embodiment of a power tool is provided. The electric tool includes a motor as a power source. Specifically, the electric machine can be configured with the electric machine stator assembly 100 of any of the foregoing embodiments or combinations thereof; alternatively, the motor may be directly configured as the motor in any of the foregoing embodiments or combinations thereof, and thus have corresponding technical effects.

Further, in consideration of the fact that the angle grinder is applied to an environment with a large amount of metal dust and the electric hammer is applied to an environment with a large amount of dust, the sealing property of the motor has a great influence on the reliability of such electric tools. Therefore, when the motor stator assembly or the motor with the improvement is applied to the electric tool, the technical effect is particularly outstanding.

It should be noted that the motor stator assembly, the motor and other parts of the power tool provided by the present application may be designed, manufactured and sold separately, or they may be assembled together and sold as a whole. Whether formed as a monomer before combination or as a whole after combination, are within the scope of the present application.

The above detailed description is merely illustrative of the present application and is not intended to be limiting. In the present application, relative terms such as left, right, up, and down are used to describe relative positional relationships, and are not intended to limit absolute positions. Various changes and modifications can be made by one skilled in the art without departing from the scope of the present application, and all equivalent technical solutions also belong to the scope of the present application, and the protection scope of the present application should be defined by the claims.

Claims

1. An electric machine stator assembly, comprising:

a stator core (110) having a yoke portion (111), and a plurality of teeth portions (112) provided on the yoke portion (111) at intervals in a circumferential direction, each of the teeth portions (112) extending in a radial direction;

a stator winding (120) including a winding wire (121) wound around each of the teeth (112); and

a plurality of rubber covers (130) configured to cover the windings (121) on the respective teeth (112);

wherein each of the rubber casings (130) has stator slots (140) spaced apart in a circumferential direction of the stator core (110) therebetween.

2. The electric machine stator assembly according to claim 1, characterized in that each tooth (112) extends radially inward or radially outward on the yoke (111).

3. The electric machine stator assembly according to claim 1, characterized in that the glue housing (130) is made by a glue pouring process; optionally, the glue casing (130) is made of glue having a thermal conductivity not less than 0.2W/(m × K) by a glue pouring process; optionally, the glue casing is made to fill the gaps between the windings (121).

4. The electric machine stator assembly according to claim 1, characterized in that the portion of the glue housing (130) axially surrounding the teeth (112) and the stator windings (120) has a uniform thickness.

5. The electric machine stator assembly of claim 1, characterized in that the glue housing (130) has a profiled outer surface with depressions or protrusions for increasing surface area.

6. The electric machine stator assembly of claim 1, wherein the stator slots are constant width slots or tapered width slots.

7. The electric machine stator assembly according to claim 1, characterized in that the teeth (112) have a stop (112 a) at an end remote from the yoke (111), the plurality of glue cases (130) at least partially covering the stop (112 a); optionally, adjacent said glue cases (130) are connected to each other at the side of said stop (112 a); optionally, the stopper portion (112 a) has positioning grooves (112 b) on both ends in the circumferential direction, and the rubber cover (130) is formed to fill the positioning grooves (112 b).

8. The electric machine stator assembly according to claim 1, characterized in that the plurality of glue housings (130) are interconnected at axial ends of the stator core (110) to form a glue ring (131) such that the plurality of glue housings (130) are integral; optionally, the stator winding (120) further includes a bridge wire connected between the windings (121) wound around the respective teeth (112), and the glue ring (131) is configured to cover the bridge wire.

9. The electric machine stator assembly according to claim 1, characterized in that the stator slots extend radially from a first end of the tooth (112) near the yoke (111) to a second end of the tooth (112) facing away from the yoke (111).

10. An electric machine, comprising: a rotor; and an electric machine stator assembly (100) according to any of claims 1-9; the rotor is arranged in the middle of the motor stator assembly (100) along the axial direction.

11. The electric machine of claim 10, further comprising a fan secured to the rotor for driving air through the stator slots (140).

12. An electric power tool, characterized by comprising: an electrical machine having an electrical machine stator assembly (100) as claimed in any of claims 1 to 9, or an electrical machine as claimed in claim 10 or 11; optionally, the power tool is an angle grinder or an electric hammer.