Three-phase brushless motor

Abstract

The present invention is applicable to the field of electric motors, and provides a three-phase brushless motor, including: a stator assembly, a rotor assembly, a connection assembly and a motor drive circuit, wherein the stator assembly includes a stator core with six stator teeth, an upper insulating plate, a lower insulating plate and six coils wound on the stator teeth, the stator core and the coils are isolated by the upper insulating plate and the lower insulating plate in a buckled manner, the six coils are connected to the connection assembly in a star connection to form three phases, and the motor drive circuit is connected to the connection assembly to supply power to the stator assembly, form a magnetic field, and drive the rotor assembly to rotate. The three-phase brushless motor provided by the present invention effectively reduces the space occupied by the stator assembly while ensuring high-speed operation through reasonable arrangement of the coils and circuit design, thereby facilitating the miniaturization of the entire motor and optimizing the heat dissipation of the motor.

Description

Technical Field

[0001] The invention belongs to the field of electric motors, and in particular relates to a three-phase brushless motor. Background Art

[0002] At present, the purpose of designing the fuel vapor purification EVAP system of automobiles is to prevent the vapor in the fuel tank from entering the atmosphere, polluting the atmosphere and increasing the fuel consumption of the automobile. The gasoline vapor in the fuel tank enters the activated carbon canister through the pipeline from the outlet of the separation valve, and the gasoline molecules in the vapor are adsorbed by the activated carbon. The control component of the system is the carbon canister control solenoid valve, which cannot actively suck the vapor in the fuel into the intake manifold. The new generation of products adds a vacuum pump, which can actively extract the oil vapor, greatly improving the efficiency of the system. The core component of the vacuum pump is a high-speed brushless DC motor, which is required to have the characteristics of simple structure, reliable quality, small size and low cost. Summary of the invention

[0003] The object of the present invention is to provide a three-phase brushless motor, which can reduce the size of the motor while ensuring the motor speed requirement through structural design.

[0004] The present invention is achieved in that:

[0005] A three-phase brushless motor, comprising:

[0006] A stator assembly, comprising a stator core, an upper insulating plate, a lower insulating plate and six coils, wherein the upper insulating plate and the lower insulating plate are respectively covered on the upper and lower surfaces of the stator core, the stator core comprises a ring portion and six stator teeth connected to the ring portion and extending inward, the six stator teeth are equidistantly distributed and centrally symmetrical, the six coils are correspondingly wound on the six stator teeth, the front ends of the six stator teeth are connected to form a circular ring, the stator core and the coils are isolated by the upper insulating plate and the lower insulating plate in a manner of buckling up and down, any two centrally symmetrical coils among the six coils are electrically connected to each other, and each forms a phase winding;

[0007] A rotor assembly, comprising a rotor shaft and a rotor core symmetrically fixed on the circumference of the rotor shaft, wherein the rotor is located in the circular ring, and an air gap is left between the rotor assembly and the stator assembly;

[0008] A connection assembly, comprising a common terminal and three connection terminals, each of the phase windings having two electrical connection ends, one of which is electrically connected to the common terminal, and the other is electrically connected to one of the connection terminals;

[0009] Furthermore, the stator teeth are provided with side protrusions facing horizontally on both sides at the ends away from the ring portion, and a through opening for accommodating the wires of the coil is formed between the side protrusions of two adjacent stator teeth.

[0010] Furthermore, the upper insulating plate and the lower insulating plate contact each other and partially overlap at their intersection.

[0011] Furthermore, the upper insulating plate is provided with an upward upper protrusion at an end away from the ring portion, and the lower insulating plate is provided with a downward lower protrusion at an end away from the ring portion.

[0012] Furthermore, the upper insulating plate is provided with sockets for fixing the common terminals and the connecting terminals.

[0013] Furthermore, the upper insulating plate is provided with a wiring post on its upper surface, the wiring post is located above the ring portion, and the wires of the coil are connected to the connection structure by winding around the wiring post.

[0014] Furthermore, the stator core also includes a plurality of flanges connected to the ring portion and extending outward, and the plurality of flanges are unevenly distributed along the ring portion.

[0015] Furthermore, the socket is located directly above the ring portion, a blind hole for accommodating the common terminal or the connecting terminal is provided on the upper surface of the socket, and a through hole communicating with the blind hole is provided on the side of the socket close to the coil direction.

[0016] Furthermore, the connecting terminal includes a welding portion electrically connected to the PCB circuit and a clamping portion connected to the wire of the coil, the clamping portion includes a clamping portion body connected to the welding portion, protrusions arranged on both sides of the clamping portion body, and two hooks arranged below the clamping portion body and on the left and right, the protrusions abut against the hole wall of the blind hole, and the gap between the two hooks is smaller than the diameter of the wire core of the coil.

[0017] Furthermore, the three-phase brushless motor also includes a body, the stator assembly, the rotor assembly and the motor drive circuit are all fixed on the body, and the common terminal and the connecting terminal are fixed on the body.

[0018] The three-phase brushless motor provided by the present invention effectively reduces the space occupied by the stator assembly while ensuring high-speed operation through reasonable coil arrangement and circuit design, thereby facilitating the miniaturization of the entire motor. Reasonable magnetic circuit design optimizes the heat dissipation of the motor, and the multi-coil setting increases the heat dissipation surface of the coil, which is conducive to radiation heat dissipation. In addition, the circular array of six coils allows for a large free space between the coils, which together with the air gap between the rotor assembly and the stator assembly facilitates air circulation and heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a top view of a three-phase brushless motor according to a first embodiment of the present invention;

[0021] Figure 2 This is a star connection diagram;

[0022] Figure 3 1 is a schematic diagram of the connection of the three-phase brushless motor coils according to the first embodiment of the present invention;

[0023] Figure 4 is a connection diagram of a stator assembly and a rotor assembly according to a first embodiment of the present invention;

[0024] Figure 5 is a connection diagram of the stator assembly and the rotor assembly from another angle according to the first embodiment of the present invention;

[0025] Figure 6 is a schematic structural diagram of a stator core according to a first embodiment of the present invention;

[0026] Figure 7 is a schematic structural diagram of an upper insulating plate according to Embodiment 1 of the present invention;

[0027] Figure 8 is a schematic structural diagram of a lower insulating plate according to a first embodiment of the present invention;

[0028] Fig. 9 It is a schematic diagram of the connection between the connection assembly and the stator assembly of the first embodiment of the present invention;

[0029] Fig.10 is a schematic diagram of the connection between the connection terminal and the socket of the first embodiment of the present invention, which is a partial cutaway diagram;

[0030] Fig.11 It is a partial schematic diagram of a motor provided in the second embodiment of the present invention.

[0031] Description of Figure Numbers:

[0032] Label name Label name 100 Stator components 200 Rotor assembly 110 Stator core 210 Rotor shaft 111 Ring 220 Rotor core 112 Stator teeth 300 Connecting components 1121 Side bulge 310 Common terminal 113 Flange 320 Connection Terminals 120 Upper insulation board 321 Welding Department 121 First insulation sheet 322 Card connection 122 Upper bulge 3221 Bump 123 Cable Column 3222 Hook 124 socket 400 Body 1241 Blind Via 500 PCB board 1242 Through Hole 125 Avoid gaps 130 Lower insulation board 131 Second insulation sheet 132 Lower bulge 140 Coil DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] It should also be noted that the directional terms such as left, right, up and down in the embodiments of the present invention are merely relative concepts or are based on the normal use status of the product and should not be considered as restrictive.

[0037] Embodiment 1

[0038] Please refer to Figures 1 to 10 The present embodiment provides a three-phase brushless motor, including a stator assembly 100, a rotor assembly 200, a motor drive circuit, a connecting assembly 300 electrically connecting the motor drive circuit to the stator assembly 100, and a body 400 fixing the stator assembly 100, the rotor assembly 200 and the motor drive circuit.

[0039] Please refer to Figure 4 and Figure 6 The stator assembly 100 includes a stator core 110, an upper insulating plate 120, a lower insulating plate 130 and six coils 140. The upper insulating plate 120 and the lower insulating plate 130 are respectively covered on the upper and lower surfaces of the stator core 110. The stator core 110 includes a ring portion 111 and six stator teeth 112 connected to the ring portion 111 and extending inward. The six stator teeth 112 are equidistantly distributed and centrally symmetrical. The six coils 140 are respectively wound on the six stator teeth 112. The stator core 110 and the six coils 140 are isolated by the upper insulating plate 120 and the lower insulating plate 130 in a manner of being buckled up and down. Any two centrally symmetrical coils 140 among the six coils 140 are electrically connected to each other and form a phase winding respectively.

[0040] Please refer to Figure 4 The rotor assembly 200 includes a rotor shaft 210 and a rotor core 220 symmetrically fixed to the circumference of the rotor shaft 210. The front ends of the six stator teeth 112 are connected to form a circular ring. The rotor assembly 200 is located in the circular ring, and an air gap is left between the rotor assembly 200 and the stator assembly 100.

[0041] Please refer to Figure 4 or Fig. 9 The connection assembly 300 includes a common terminal 310 and three connection terminals 320. Each phase winding includes two electrical connection ends, one of which is connected to the common terminal 310 and the other is connected to a connection terminal 320. One connection terminal 320 is connected to one phase winding. The three connection terminals 320 are all electrically connected to the motor drive circuit.

[0042] The six coils 140 are connected in star configuration to form three phases. Figure 2 The diagram is a star connection diagram, o is a common terminal 310, a, b, c are connection terminals 320, and A, B, C are phase windings. a, b, c are connected to the motor drive circuit, and by controlling the switches of the current input at each end of a, b, c, a corresponding magnetic field is generated between the ABC phase windings.

[0043] Please refer to Figure 2 and Figure 3 , the six coils 140 in this embodiment are marked clockwise as coil 1, coil 2, coil 3, coil 4, coil 5, and coil 6, respectively. Each coil 140 has two terminals, wherein two centrally symmetrical coils 140 are connected, i.e., coil 1 and coil 4 are connected to form an A-phase winding, coil 2 and coil 5 are connected to form a B-phase winding, and coil 3 and coil 6 are connected to form a C-phase winding. One terminal of the three phase windings is connected together, and the connection point is marked as o. The other terminals of the three phase windings are marked as a, b, and c, respectively, and are electrically connected to the motor drive circuit. After the phase windings are powered, a magnetic field different from the magnetic field direction of the rotor assembly 200 is generated in the ring, thereby causing the rotor assembly 200 to rotate.

[0044] The three-phase brushless motor of this embodiment effectively reduces the space occupied by the stator assembly 100 while ensuring high-speed operation through reasonable arrangement and circuit design of the coils 140, thereby facilitating the miniaturization of the entire motor. Reasonable magnetic circuit design optimizes the heat dissipation of the motor, and the multi-coil 140 arrangement increases the heat dissipation surface of the coils 140, which is conducive to radiation heat dissipation. In addition, the circular array of six coils 140 allows for a large free space between the coils 140, which together with the air gap between the rotor assembly 200 and the stator assembly 100 facilitates air circulation and heat dissipation.

[0045] Please refer to Figure 6 The stator teeth 112 are provided with side protrusions 1121 extending horizontally on both sides at the ends away from the ring portion 111, and a through hole for accommodating the wires of the coil 140 is formed between the side protrusions 1121 of two adjacent stator teeth 112. The setting of the side protrusions 1121 limits the winding area of ​​the coil 140 and reduces the size of the through hole, thereby reducing the magnetic flux leakage of the coil 140 at this location. The through hole is a process notch for winding the coil 140. The size of the through hole is minimized as long as the winding process requirements are met.

[0046] Please refer again Figure 6 The stator core 110 further includes a plurality of flanges 113 connected to the ring portion 111 and extending outward, and the plurality of flanges 113 are unevenly distributed along the ring portion 111. In the present embodiment, there are three flanges 113. In other embodiments, there may be more than four flanges 113, as long as a stable fixed connection can be achieved. The uneven arrangement of the flanges 113 is intended to facilitate installation. Specifically, the flanges 113 are a fixed connection structure for fixing the stator assembly 100 to the motor housing. Through the uneven arrangement design, the operator only needs to align the flanges 113 with the corresponding mounting holes of the motor housing to perform installation and fixing, without having to distinguish the front and back sides and positions of other components of the stator assembly 100.

[0047] Please refer to Figure 7 and Figure 8 The upper insulating plate 120 and the lower insulating plate 130 are provided with an avoidance notch 125 in the position area of ​​the flange 113. The purpose of setting the avoidance notch 125 is not only to provide an avoidance space for the connection between the flange 113 and the motor housing, but also to limit the installation position of the upper insulating plate 120, the lower insulating plate 130 and the stator core 110. In combination with the following description, the connection assembly 300 (including the common terminal 310 and the connection terminal 320) is arranged on the upper insulating plate 120, and the connection terminal 320 is electrically connected to the motor drive circuit. The avoidance notch 125 corresponds to the position of the flange 113, and the position of the avoidance notch 125 and the connection terminal 320 is fixed. Then, through the uneven arrangement of the flange 113, the position of each part of the stator assembly 100 relative to the flange 113 is uniquely fixed. Based on this correspondence, the problem of incorrect connection between the various parts of the stator assembly 100 and the motor drive circuit and the connection terminal 320 is effectively avoided.

[0048] In this embodiment, the stator core 110 is made of silicon steel or soft magnetic cast iron. Preferably, the stator core 110 is made of laminated silicon steel sheets that are insulated from each other. The arrangement of the laminated silicon steel sheets can effectively reduce eddy current losses and lower temperature rise.

[0049] Please refer to Figure 4 , Figure 5 , Figure 7 and Figure 8, the stator core 110 and the coil 140 are insulated and isolated by the upper insulating plate 120 and the lower insulating plate 130. The upper insulating plate 120 is provided with a first insulating sheet 121 at the position where it intersects with the lower insulating plate 130, and the lower insulating plate 130 is provided with a second insulating sheet 131 at the position where it intersects with the upper insulating plate 120. When the upper insulating plate 120 and the lower insulating plate 130 are buckled up and down, the first insulating sheet 121 fits with the second insulating sheet 131. Because the first insulating sheet 121 and the second insulating sheet 131 have overlapping intersections, the contact and matching of the upper insulating plate 120 and the lower insulating plate 130 after assembly is ensured to avoid poor insulation caused by transfer errors or individual defective products of the upper insulating plate 120 and the lower insulating plate 130 during the assembly process, thereby ensuring the insulation stability between the stator core 110 and the coil 140.

[0050] Please refer to Figure 7 and Figure 8 The upper insulating plate 120 is provided with an upward upper protrusion 122 at the end away from the ring portion 111, and the lower insulating plate 130 is provided with a downward lower protrusion 132 at the end away from the ring portion 111. The arrangement of the upper protrusion 122 and the lower protrusion 132 further defines the winding area of ​​the coil 140. In particular, when the size of the side protrusion 1121 is small, and the number of turns of the coil 140 is large, so that the coil 140 may be separated from the winding area at the through opening, the upper protrusion 122 and the lower protrusion 132 can be appropriately increased in height according to actual needs to avoid this situation.

[0051] Please refer to Figure 4 and Figure 7 The upper insulating plate 120 is provided with a wiring post 123 on its upper surface. The wiring post 123 is located above the ring portion 111. The wires of the coil 140 are connected to the connection structure through the wiring post 123. As shown in the figure, the coil 140 is wound on the stator teeth 112. The connection wiring between the coil 140 and the coil 140 and the connection wiring between the coil 140 and the common terminal 310 and the connection terminal 320 are arranged on the periphery of the coil 140, that is, above the ring portion 111. The wiring post 123 guides and ensures the route of the wiring and fixes the wiring. The peripheral setting can reduce the influence of the wiring on the magnetic field. In addition, the centralized setting makes the structural layout of the entire stator assembly 100 compact, which is conducive to the miniaturization of the overall structure.

[0052] Please refer to Figure 7 or Fig. 9The upper insulating plate 120 is provided with a socket 124 for fixing the common terminal 310 and the connecting terminal 320. The common terminal 310 and the connecting terminal 320 are fixed on the upper insulating plate 120 on the same side so that the wires can be connected on the same side, thereby improving the operation efficiency. The common terminal 310 and the connecting terminal 320 are fixed on the upper insulating plate 120 to facilitate the connection of the wires of the coil 140. The specific structure of the socket 124 and the common terminal 310 or the connecting terminal 320 is not limited, and only needs to achieve fixed connection.

[0053] In one embodiment, see Fig. 9 , the socket 124 is located directly above the ring portion 111. A blind hole 1241 is provided on the upper surface of the socket 124 to accommodate the insertion of the common terminal 310 or the connecting terminal 320, and a through hole 1242 is provided on the side of the socket 124 close to the coil 140 to communicate with the blind hole 1241. The wire end of the coil 140 is inserted into the through hole 1242, and the common terminal 310 or the connecting terminal 320 is inserted into the blind hole 1241 to connect with the exposed wire end. The through hole 1242 runs through to the other side of the socket 124 away from the coil 140 to facilitate the insertion of the wire and provide a window for observing the connection result.

[0054] The connection parts of the common terminal 310 and the connection terminal 320 with the wires are optimized to improve the stability of the connection and the convenience of operation. The specific design is as follows:

[0055] Please refer to Fig.10, the connecting terminal 320 includes a welding portion 321 welded to the motor drive circuit and a clamping portion 322 connected to the wire. The icon 500 is a PCB board 500 printed with the motor drive circuit. The clamping portion 322 includes a clamping portion 322 body connected to the welding portion 321, a convex block 3221 arranged on both sides of the clamping portion 322 body, and two hooks 3222 arranged below the clamping portion 322 body and arranged on the left and right. When the clamping portion 322 is inserted into the blind hole 1241, there is a gap between the clamping portion 322 body and the blind hole 1241, and the convex block 3221 abuts against the hole wall of the blind hole 1241, exerting an external force on the hole wall to deform it, so that the clamping portion 322 is fixed to the blind hole 1241 and cannot be disassembled without a certain external force. There is a gap between the two hooks 3222 arranged on the left and right, and there is a space for accommodating the wire core between the two hooks 3222 and the clamping portion 322 body. When connecting, pass the wire core through the gap between the two hooks 3222 and enter the accommodation space. The gap between the two hooks 3222 is smaller than the diameter of the wire core, so as to prevent the wire core from escaping from the accommodation space. The connecting terminal 320 is made of metal material. When inserted, the hook 3222 is squeezed by the wire core and has forces on both sides, causing it to deform elastically. After the wire core reaches the accommodation space, the hook 3222 returns to its original shape under the action of the elastic restoring force. The distance between the hook head of the hook 3222 and the lower surface of the main body of the clamping part 322 is smaller than the diameter of the wire core, and the wire core is squeezed to achieve fastening with the connecting terminal 320.

[0056] The common terminal 310 includes three clamping parts 322 connected to the electric wires and connecting parts respectively connected to the clamping parts 322. The structure of the clamping parts 322 is the same as that of the connecting terminal 320, and will not be described again.

[0057] In one embodiment, the motor further includes an impeller sleeved on the rotor shaft 210 and rotating with the rotor shaft 210. The provision of the impeller accelerates air circulation in the motor interior space and accelerates heat dissipation.

[0058] Embodiment 2

[0059] Please refer to Fig.11 The difference between this embodiment and the first embodiment is that the common terminal 310 and the connection terminal 320 are fixed on the body 400 instead of the upper insulating plate 120. The wires of the coil 140 are led out of the upper insulating plate 120 and connected to the connection terminal 320 or the common terminal 310. The common terminal 310 and the connection terminal 320 can be arranged according to the internal space of the body 400, and the layout space is highly selective.

[0060] Accordingly, there is no need to set a socket for fixing the connection assembly 300 on the upper insulating plate 120 , and the wiring column can be further removed and the coverage area of ​​the upper insulating plate 120 on the ring portion 111 can be reduced.

[0061] Compared with the design in which the connection assembly 300 is fixed on the upper insulating plate 120, this design simplifies the structure of the upper insulating plate 120, reduces the distance between the PCB board and the upper insulating plate 120, and thus reduces the size of the entire motor.

[0062] For other structures of the three-phase brushless motor provided in this embodiment, please refer to the first embodiment, and the structure and the technical effects it brings will not be repeated here.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-phase brushless motor, characterized in that: include: A stator assembly, comprising a stator core, an upper insulating plate, a lower insulating plate and six coils, wherein the upper insulating plate and the lower insulating plate are respectively covered on the upper and lower surfaces of the stator core, the stator core comprises a ring portion and six stator teeth connected to the ring portion and extending inward, the six stator teeth are equidistantly distributed and centrally symmetrical, the six coils are correspondingly wound on the six stator teeth, the front ends of the six stator teeth are connected to form a circular ring, the stator core and the coils are isolated by the upper insulating plate and the lower insulating plate in a manner of buckling up and down, any two centrally symmetrical coils among the six coils are electrically connected to each other, and each forms a phase winding; A rotor assembly, comprising a rotor shaft and a rotor core symmetrically fixed on the circumference of the rotor shaft, wherein the rotor is located in the circular ring, and an air gap is left between the rotor assembly and the stator assembly; A connection assembly, comprising a common terminal and three connection terminals, each of the phase windings having two electrical connection ends, one of which is electrically connected to the common terminal, and the other is electrically connected to one of the connection terminals; A motor driving circuit, electrically connected to the three connecting terminals; The upper insulating plate is provided with a first insulating sheet at a position where it intersects with the lower insulating plate, and the lower insulating plate is provided with a second insulating sheet at a position where it intersects with the upper insulating plate, and the first insulating sheet and the second insulating sheet are attached to each other; the first insulating sheet and the second insulating sheet have an overlapping intersecting portion; The upper insulating plate is provided with a socket for fixing the common terminal and the connecting terminal; The stator core further comprises a plurality of flanges connected to the ring portion and extending outward, wherein the plurality of flanges are unevenly distributed along the ring portion; the upper insulating plate and the lower insulating plate are provided with avoidance notches in the position area of ​​the flanges, wherein the avoidance notches correspond to the positions of the flanges; The socket is located directly above the ring portion, a blind hole for accommodating the common terminal or the connecting terminal is provided on the upper surface of the socket, and a through hole communicating with the blind hole is provided on the side of the socket close to the coil direction; The connecting terminal comprises a welding portion electrically connected to the motor drive circuit and a clamping portion connected to the wire of the coil, the clamping portion comprises a clamping portion body connected to the welding portion, convex blocks arranged on both sides of the clamping portion body, and two clamping hooks arranged below the clamping portion body and arranged on the left and right sides, there is a gap between the clamping portion body and the blind hole, the convex block abuts against the hole wall of the blind hole, an accommodating space for accommodating the coil is reserved between the two clamping hooks and the clamping portion body, and the gap between the two clamping hooks is smaller than the diameter of the wire core of the coil; The stator teeth are provided with side protrusions on both sides of the horizontal direction at the ends away from the ring portion, and a through hole for accommodating the wires of the coil is formed between the side protrusions of two adjacent stator teeth; The upper insulating plate is provided with an upward upper protrusion at an end away from the ring portion, and the lower insulating plate is provided with a downward lower protrusion at an end away from the ring portion.

2. The three-phase brushless motor according to claim 1, characterized in that: The upper insulating plate is provided with a wiring post on its upper surface, and the wiring post is located above the ring portion.

3. The three-phase brushless motor according to claim 1, characterized in that: The three-phase brushless motor further comprises a body, the stator assembly, the rotor assembly and the motor drive circuit are all fixed on the body, and the common terminal and the connecting terminal are fixed on the body.

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