An outer rotor motor for driving a cooling fan of an automobile

Abstract

The application discloses an outer rotor motor for driving a cooling fan of an automobile, which comprises a controller assembly, a conductive support and a PCBA board, an armature assembly and an outer rotor assembly. The conductive support comprises three mounting hole portions, and the outer periphery of the mounting hole portions is provided with terminal protection portions. The terminal protection portions and the mounting hole portions are connected through connecting rods. The back of the connecting rod is provided with a positioning slot. One conductive connecting rod is mounted on each mounting hole portion. The middle part of the conductive connecting rod is embedded in the positioning slot. The tail end of the conductive connecting rod is a connecting terminal and is located in the corresponding terminal protection portion. The connecting terminal is inserted into the corresponding conductive hole on the PCBA board and is welded and fixed. The conductive connecting rod electrically connects the armature assembly and the PCBA board. When the conductive connecting rod is welded, the outer rotor motor can effectively protect the dropped soldering tin and avoid the short circuit of the motor.

Description

TECHNICAL FIELD

[0001] The present application relates to an outer rotor motor, in particular to an outer rotor motor for driving a cooling fan of an automobile. BACKGROUND

[0002] The current outer rotor motor for driving a cooling fan of an automobile comprises a controller assembly, the controller assembly comprises a shell composed of a heat dissipation seat and a rear end cover, a conductive support and a PCBA board are arranged in the shell, a central shaft is arranged on the front surface of the heat dissipation seat, an armature assembly is mounted on the front surface of the heat dissipation seat, an outer rotor assembly is rotatably mounted on the central shaft, an inductor mounting area, a conductive support mounting area, a wire harness connector area and a heat conduction platform are arranged on the heat dissipation seat, the conductive support is placed in the conductive support mounting area, an inductor is arranged in the inductor mounting area, the wire harness connector area is provided with wire harness conductive pins, the inductor and the wire harness conductive pins are welded and fixed with corresponding conductive holes on the PCBA board, and a conductive connecting rod is inserted on the conductive support, the conductive connecting rod electrically connects the armature assembly and the PCBA board together. When the conductive connecting rod and the PCBA board are welded, the solder may fall along the conductive connecting rod, and the falling solder is not protected or collected, so that the pins on the PCBA board may be mistakenly touched by the falling solder, causing the PCBA board to be short-circuited.

[0003] In addition, the armature assembly is electrically connected to the wire harness winding and the PCBA board of the controller assembly through the conductive connecting rod on the conductive support, and a metal hook is embedded on the insulating end cover of the armature assembly, the metal hook has a connecting rod hook portion for connecting the conductive connecting rod and a wire harness hook portion for allowing the wire harness to pass through. However, when the output power of the brushless motor increases, for example, to 600W, the number of wire harnesses of the armature winding will be relatively large, and the number of wire harnesses passing through the wire harness hook portion will also be relatively large. However, the current wire harness hook portion obviously cannot meet the winding requirements of the wire harnesses, and the insulating skin of the wire harnesses may be damaged during clamping and welding, so that the wire harnesses are welded together with the metal hook. However, due to the large number of wire harnesses wound on the wire harness hook portion, the wire harnesses may cross each other, so that the insulating skin of the wire harnesses wrapped inside the wire harness hook portion may not be damaged during clamping and welding, thereby causing the wire harnesses not to be electrically connected to other wire harnesses, and the wiring of the armature assembly may be incorrect and unable to work normally. SUMMARY

[0004] The technical problem to be solved by the present application is to provide an outer rotor motor for driving a cooling fan of an automobile, which can effectively protect the falling solder during welding of the conductive connecting rod and avoid short circuit of the motor.

[0005] The technical scheme of the present application is as follows: a kind of outer rotor motor for driving automobile cooling fan, including controller assembly, the controller assembly includes the shell consisting of heat dissipation seat and rear end cover, electrically conductive support and PCBA board are arranged in the shell, the front of the heat dissipation seat is provided with center shaft, the front of the heat dissipation seat is equipped with armature assembly, the outer rotor assembly is rotatably installed in the center shaft, the heat dissipation seat is provided with inductance installation area, electrically conductive support installation area, wire harness connector area and heat conduction platform, the electrically conductive support is placed in electrically conductive support installation area, inductance is arranged in inductance installation area, wire harness connector area is provided with wire harness conductive pin, the inductance and wire harness conductive pin are all welded and fixed with corresponding electrically conductive hole on PCBA board, three through holes are arranged in electrically conductive support installation area on the heat dissipation seat, the electrically conductive support includes three mounting hole parts, the outer periphery of the mounting hole part is provided with half-closed terminal protection part, the terminal protection part and the mounting hole part are connected by connecting rod, the back of the connecting rod is provided with two positioning grooves extending to the terminal protection part and the mounting hole part respectively, one electrically conductive connecting rod is installed on each mounting hole part, one end of the electrically conductive connecting rod is inserted into corresponding mounting hole part and passes through the through hole, the middle part of the electrically conductive connecting rod is embedded in corresponding positioning groove, the tail end of the electrically conductive connecting rod is connected terminal and is in corresponding terminal protection part, the connected terminal is inserted into corresponding electrically conductive hole on PCBA board and welded and fixed, the electrically conductive connecting rod is electrically connected with armature assembly and PCBA board.

[0006] As a preferred scheme, the armature assembly comprises a stator core and a back insulating end cover and a front insulating end cover fixed to the back end and the front end of the stator core respectively, a stator winding is wound around the back insulating end cover and the front insulating end cover, three metal hooks are fixed to the front insulating end cover, the stator winding is wound according to the winding rule and is clamped and fixed to the metal hooks across the metal hooks, so that the stator winding forms a three-phase winding; the metal hook comprises a hook body which is inserted and fixed to the front insulating end cover, each hook body is provided with a connecting rod hook portion which facilitates the insertion of a corresponding conductive connecting rod, the hook body is also provided with two wire harness hook portions, the wire harness hook portion is provided with a hooking groove which facilitates the crossing of the wire harness, the hooking groove comprises a back groove surface, a front groove surface and a connecting arc surface connecting the back groove surface and the front groove surface, the included angle between the back groove surface and the front groove surface and the axis of the stator core is 85-90°, and the opening of the hooking groove faces the center of the stator core. In this way, when winding, the wire harness is sequentially arranged on the back groove surface of the hooking groove and is arranged in order, and the wire harness does not cross due to the excessively large inclination angle, when clamping and welding, the back groove surface and the front groove surface of the hooking groove are close to each other and can damage the insulation of all wire harnesses in the hooking groove, so that each wire harness can be well welded, the armature assembly works more reliably, and since each hook body is provided with two wire harness hook portions, more wire harnesses can be selected to be wound in the wire harness hook portion, so as to meet the winding requirements of a motor with greater power.

[0007] As a preferred scheme, the back groove surface and the front groove surface are parallel to each other and the included angle between the back groove surface and the front groove surface and the axis of the stator core is 90°.

[0008] As a preferred scheme, the distance between the back groove surface and the front groove surface is greater than the diameter of one wire harness and less than the diameter of two wire harnesses. In this way, the wire harness can be conveniently entered into the hooking groove when winding, and the wire harness can be ensured not to cross.

[0009] As a preferred scheme, the wire harness hook portion is provided with an expanded guide portion at the opening. The guide portion can facilitate the wire harness to better enter the hooking groove when winding.

[0010] As a preferred scheme, the front insulation end cover is a split structure, the front insulation end cover comprises a middle phase ring and a plurality of front tooth end cover parts outside the middle phase ring, the front tooth end cover parts are fixed one by one on the front side of the tooth part of the stator core, the middle phase ring is fixed on the middle part of the stator core, the metal hook is inserted and fixed on the middle phase ring, the outer side and the inner side of the front tooth end cover part are respectively provided with a front outer positioning protrusion and a front inner positioning protrusion, the back insulation end cover comprises a middle insulation ring part and a plurality of back tooth end cover parts connected outside the middle insulation ring part, the outer side and the inner side of each back tooth end cover part are respectively provided with a back outer positioning protrusion and a back inner positioning protrusion, the back outer positioning protrusion and the front outer positioning protrusion jointly constrain the outer side end of the wire harness winding, and the back inner positioning protrusion and the front inner positioning protrusion jointly constrain the inner side end of the wire harness winding. In this way, the wire harness can be better constrained and wound on the back tooth end cover part and the front tooth end cover part during winding, and the wire harness is more tidy

[0011] As a preferred scheme, the terminal protection part comprises a bottom protection plate part and a side protection plate part, the back surface of the bottom protection plate part is connected with the back surface of the connecting rod, and the side protection plate part is provided with a avoiding notch corresponding to the position of the connecting rod. The terminal protection part uses the bottom protection plate to protect the bottom to prevent solder from falling onto the heat dissipation seat, and the side protection plate part is used to protect the side surface, so that the protection effect is better.

[0012] As a preferred scheme, the middle of the three mounting hole parts is provided with a positioning ring part, the positioning ring part is connected with the three mounting hole parts through connecting ribs, and the corresponding conductive support mounting area is provided with a positioning boss inserted into the positioning ring part. In this way, the conductive support can be better installed by using the positioning ring part and the positioning boss.

[0013] As a preferred scheme, the conductive support mounting area is a sink region, the conductive support is mounted in the sink region, and the conductive support mounting area is provided with a positioning sink region corresponding to the shape of the terminal protection part. The position of the conductive support can be better determined by using the positioning sink region, so that the conductive connecting rod can pass through the through hole of the heat dissipation seat more accurately.

[0014] The technical scheme is adopted, and the effect of the application is that: three through holes are arranged in the conductive support mounting area on the heat dissipation seat, the conductive support comprises three mounting hole portions, an outer periphery of the mounting hole portion is provided with a semi-closed terminal protection portion, the terminal protection portion and the mounting hole portion are connected through a connecting rod, a back portion of the connecting rod is provided with a positioning slot extending to the terminal protection portion and the mounting hole portion at two ends, respectively, one conductive connecting rod is arranged on each mounting hole portion, one end of the conductive connecting rod is inserted into the corresponding mounting hole portion and passes out from the through hole, the middle part of the conductive connecting rod is embedded in the corresponding positioning slot, and the tail end of the conductive connecting rod is a connecting terminal and is arranged in the corresponding terminal protection portion, the connecting terminal is inserted into the corresponding conductive hole on the PCBA board and is welded and fixed, the conductive connecting rod electrically connects the armature assembly and the PCBA board, therefore, when the connecting terminal is welded by being inserted into the hole of the PCBA board, the terminal protection portion can effectively protect the connecting terminal, even if the solder falls, the solder can also be prevented from contacting the pin of the PCBA board due to the protection of the semi-closed terminal protection portion, and the short circuit phenomenon is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0015] The application is further described below in combination with the drawings and examples.

[0016] Figure 1 is a perspective view of an embodiment of the application;

[0017] Figure 2 is an exploded view of the outer rotor assembly hidden;

[0018] Figure 3 is an exploded view of the outer rotor assembly hidden from another angle;

[0019] Figure 4 is a perspective view of the armature assembly;

[0020] Figure 5 is a perspective view of the intermediate phase ring and the metal hook;

[0021] Figure 6 is a side view of the metal hook;

[0022] Figure 7 is Figure 3 is an enlarged view at A;

[0023] In the attached diagram: 1. Outer rotor assembly; 2. Controller assembly; 21. Heat sink; 211. Conductive support mounting area; 2111. Positioning boss; 2112. Slotted area; 212. Inductor mounting area; 213. Wiring harness connector area; 22. Rear end cover; 23. Central shaft; 3. Armature assembly; 31. Stator core; 32. Stator winding; 33. Front insulating end cover; 331. Intermediate phase loop; 332. Front outer positioning protrusion; 333. Front inner positioning protrusion; 34. Metal guard hook; 3 41. Hook body; 342. Embedded pin; 343. Wire harness hook; 344. Connecting rod hook; 345. Back side groove; 346. Front side groove; 347. Guide part; 35. Back insulating end cap; 4. PCBA board; 5. Conductive bracket; 51. Mounting hole; 52. Terminal protection part; 53. Positioning ring; 54. Positioning groove; 55. Connecting rod; 56. Reinforcing rib; 57. Connecting rib; 6. Conductive connecting rod; 61. First rod segment; 62. Second rod segment; 63. Third rod segment. Detailed Implementation

[0024] The present invention will be further described in detail below through specific embodiments.

[0025] like Figures 1 to 7 As shown, an external rotor motor for driving an automotive cooling fan includes a controller assembly 2. The controller assembly 2 includes a housing consisting of a heat sink 21 and a rear end cover 22. A conductive bracket 5 and a PCBA board 4 are disposed inside the housing. A central shaft 23 is disposed on the front side of the heat sink 21. An armature assembly 3 is mounted on the front side of the heat sink 21. An external rotor assembly 1 is rotatably mounted on the central shaft 23. An inductor mounting area 212, a conductive bracket 5 mounting area 211, a wire harness connector area 213, and a heat-conducting platform are disposed on the heat sink 21. The conductive bracket 5 is placed in the conductive bracket 5 mounting area 211. An inductor is disposed in the inductor mounting area 212. A wire harness conductive pin is disposed in the wire harness connector area 213. The inductor and the wire harness conductive pin are welded and fixed to corresponding conductive holes on the PCBA board 4. An insulating thermally conductive adhesive is disposed between the PCBA board 4 and the heat-conducting platform, thereby conducting the heat of the PCBA board 4 to the heat sink 21.

[0026] The heat dissipation seat 21 is provided with three through holes in the conductive support 5 mounting area 211. The conductive support 5 includes three mounting hole portions 51, the outer periphery of the mounting hole portion 51 is provided with a semi-closed terminal protection portion 52, the terminal protection portion 52 and the mounting hole portion 51 are connected by a connecting rod 55, the back of the connecting rod 55 is provided with a positioning slot 54 extending to the terminal protection portion 52 and the mounting hole portion 51 respectively, one conductive connecting rod 6 is mounted on each mounting hole portion 51, one end of the conductive connecting rod 6 is inserted into the corresponding mounting hole portion 51 and passes out from the through hole, a waterproof sleeve is arranged between the conductive connecting rod 6 and the through hole, the middle part of the conductive connecting rod 6 is embedded in the corresponding positioning slot 54, the tail end of the conductive connecting rod 6 is a connecting terminal and is in the corresponding terminal protection portion 52, the connecting terminal is inserted into the corresponding conductive hole on the PCBA board 4 and is welded and fixed, the conductive connecting rod 6 electrically connects the armature assembly 3 and the PCBA board 4.

[0027] The conductive connecting rod 6 in the embodiment is a three-section connecting rod, which includes a first rod section 61, a second rod section 62 and a third rod section 63, the first rod section 61 is inserted into the mounting hole portion 51 and the through hole, the second rod section 62 is embedded in the corresponding positioning slot 54, and the third rod section 63 is a connecting terminal, the third rod section 63 is protected by the terminal protection portion 52 and is welded with the PCBA board 4.

[0028] As shown in Figure 7 The terminal protection portion 52 includes a bottom protection plate portion and a side protection plate portion, the back of the bottom protection plate portion is connected with the back of the connecting rod 55, and the side protection plate portion is provided with an avoiding gap corresponding to the position of the connecting rod 55. The terminal protection portion 52 protects the bottom by the bottom protection plate portion to prevent solder from falling onto the heat dissipation seat 21, and the side protection plate portion is used to protect the side to achieve better protection effect.

[0029] The middle of the three mounting hole portions 51 is provided with a positioning ring portion 53, the positioning ring portion 53 is connected with the three mounting hole portions 51 by connecting ribs 57, and the conductive support 5 mounting area is provided with a positioning boss 2111 inserted into the positioning ring portion 53. The positioning ring portion 53 and the positioning boss 2111 can better install the conductive support 5. The three terminal protection portions 52 are further connected with reinforcing ribs 56, so that the entire conductive support 5 is hollow but has sufficient strength. In order to better place the conductive support 5, the conductive support 5 mounting area 211 is a sink region 2112, the conductive support 5 is mounted in the sink region 2112, and the conductive support 5 mounting area 211 is provided with a positioning sink region corresponding to the shape of the terminal protection portion 52. The positioning sink region can better determine the position of the conductive support 5, so as to ensure that the conductive connecting rod 6 can pass through the through hole of the heat dissipation seat 21 more accurately.

[0030] AsFigures 2 to 6 As shown, the armature assembly 3 comprises a stator core 31 and a back insulating end cover 35 and a front insulating end cover 33 fixed to the back end and front end of the stator core 31 respectively, a stator winding 32 is wound around the back insulating end cover 35 and the front insulating end cover 33, three metal hooks 34 are fixed to the front insulating end cover 33, the stator winding 32 is wound according to the winding rule and is clamped and fixed to the metal hooks 34, so that the stator winding 32 forms a three-phase winding; the metal hook 34 comprises a hook body 341 which is inserted and fixed to the front insulating end cover 33, each hook body 341 is provided with a link hook portion 344 for facilitating the insertion of the corresponding conductive link 6, the hook body 341 is also provided with two wire harness hook portions 343, which provide an additional choice for winding, facilitate winding and also avoid the overlapping of the wire harness on one hook portion, the overlapping wire harness is prone to poor electrical contact due to incomplete peeling during clamping and welding, the wire harness hook portion 343 is provided with a hook wire groove for facilitating the crossing of the wire harness, the hook wire groove comprises a back groove surface 345, a front groove surface 346 and a connecting arc surface connecting the back groove surface 345 and the front groove surface 346, the included angle between the back groove surface 345 and the front groove surface 346 and the axis of the stator core 31 is 85°-90°, preferably, the back groove surface 345 and the front groove surface 346 are parallel to each other and the included angle between them and the axis of the stator core 31 is 90°.

[0031] The opening of the hook wire groove faces the center of the stator core 31. In this way, during winding, the wire harness is arranged in order on the back groove surface 345 of the hook wire groove and does not cross due to excessive inclination angle, when clamping and welding, the back groove surface 345 and the front groove surface 346 of the hook wire groove move towards each other to damage the insulation of all wire harnesses in the hook wire groove, so that each wire harness can be welded well and the armature assembly works more reliably, and since there are two wire harness hook portions 343 on each hook body 341, it is convenient for more wire harnesses to choose the nearest wire harness hook portion 343 for winding, thereby meeting the winding requirements of a motor with greater power.

[0032] Preferably, the distance between the back groove surface 345 and the front groove surface 346 is greater than the diameter of one wire harness and less than the diameter of two wire harnesses. In this way, the wire harness can enter the hook wire groove conveniently during winding while ensuring that the wire harnesses do not cross. The wire harness hook portion 343 is provided with an expanded guide portion 347 at the opening. The guide portion 347 can facilitate the wire harness to enter the hook wire groove better during winding.

[0033] In this embodiment, as shown in Figure 4 and Figure 5As shown, the front insulation end cover 33 is a split structure, and includes a middle phase ring 331 and a plurality of front tooth end cover portions outside the middle phase ring 331, and the inside end of the plurality of front tooth end cover portions is connected with a connecting ring, the front tooth end cover portion and the middle phase ring 331 are a split structure, which is convenient for separate forming, and the front tooth end cover portion is one-to-one corresponding and fixed on the tooth portion front side of the stator core 31, the middle phase ring 331 is fixed on the middle portion of the stator core 31, and the metal hook 34 is inserted and fixed on the middle phase ring 331, wherein the metal hook 34 is provided with an embedded pin 342 embedded on the middle phase ring 331, and the middle phase ring 331 is also provided with a plurality of insertion pins for insertion into the hole of the stator core 31, the outside and the inside of the front tooth end cover portion are respectively provided with a front outer positioning protrusion 332 and a front inner positioning protrusion 333, the back insulation end cover 35 includes a middle insulation ring portion and a plurality of back tooth end cover portions connected outside the middle insulation ring portion, and the outside and the inside of each back tooth end cover portion are respectively provided with a back outer positioning protrusion 2111 and a back inner positioning protrusion 2111, the back outer positioning protrusion 2111 and the front outer positioning protrusion 332 jointly constrain the outside end of the wire harness winding, and the back inner positioning protrusion 2111 and the front inner positioning protrusion 333 jointly constrain the inside end of the wire harness winding. In this way, the wire harness can be better constrained and wound on the back tooth end cover portion and the front tooth end cover portion during the winding process, and the wire harness is more tidy

[0034] The above-described embodiments are only preferred embodiments of the present application, and are not intended to limit the scope of the present application. Various modifications and improvements of the technical solutions of the present application can be made without departing from the design spirit of the present application, and all should fall within the protection scope of the claims of the present application.

Claims

1. An external rotor motor for driving an automotive cooling fan, comprising a controller assembly, the controller assembly including a housing consisting of a heat sink and a rear end cover, a conductive bracket and a PCBA board disposed within the housing, a central shaft disposed on the front side of the heat sink, an armature assembly mounted on the front side of the heat sink, an external rotor assembly rotatably mounted on the central shaft, an inductor mounting area, a conductive bracket mounting area, a wiring harness connector area and a heat-conducting platform disposed on the heat sink, the conductive bracket being placed in the conductive bracket mounting area, an inductor disposed in the inductor mounting area, and a wiring harness conductive pin disposed in the wiring harness connector area, the inductor and the wiring harness conductive pin being soldered and fixed to corresponding conductive holes on the PCBA board, characterized in that: The heat sink has three through holes located in the conductive bracket mounting area. The conductive bracket includes three mounting hole portions, each with a semi-enclosed terminal protection portion on its outer periphery. The terminal protection portion is connected to the mounting hole portion via a connecting rod. The back of the connecting rod has positioning grooves extending towards the terminal protection portion and the mounting hole portion at both ends. A conductive connecting rod is mounted on each mounting hole portion. One end of the conductive connecting rod is inserted into the corresponding mounting hole portion and protrudes through the through hole. The middle portion of the conductive connecting rod is embedded in the corresponding positioning groove. The tail end of the conductive connecting rod is a connecting terminal located within the corresponding terminal protection portion. This connecting terminal is inserted into the corresponding conductive hole on the PCBA board and soldered for fixation. The conductive connecting rod electrically connects the armature assembly to the PCBA board. The armature assembly includes a stator core and a back insulating end cap and a front insulating end cap fixed to the back and front ends of the stator core, respectively. A stator winding is wound between insulating end caps. Three metal hooks are fixed on the front insulating end cap. The stator winding is wound according to a winding pattern and passes over the metal hooks, which are then clamped and welded to them, forming a three-phase stator winding. The metal hooks include hook bodies that are inserted and fixed to the front insulating end caps. Each hook body has a connecting hook portion for easy insertion of a corresponding conductive connecting rod. The hook body also has two wire harness hook portions. The wire harness hook portions have hook grooves for easy passage of the wire harness. The hook groove includes a back groove surface, a front groove surface, and a connecting arc surface connecting the back groove surface and the front groove surface. The opening of the hook groove faces the center of the stator core. The back groove surface and the front groove surface are parallel to each other and form an angle of 90° with the axis of the stator core. The distance between the back groove surface and the front groove surface is greater than the diameter of one wire harness but less than the diameter of two wire harnesses. The wire harness hook portion has a flared guide portion at the opening.

2. The external rotor motor for driving an automotive cooling fan as described in claim 1, characterized in that: The front insulating end cover is a split structure, comprising a central phase ring and several front toothed end cover portions located outside the central phase ring. The front toothed end cover portions are fixed one-to-one to the front toothed side of the stator core. The central phase ring is fixed in the middle of the stator core. The metal protective hook is inserted and fixed on the central phase ring. The outer and inner sides of the front toothed end cover portions are respectively provided with front outer positioning protrusions and front inner positioning protrusions. The back insulating end cover comprises a central insulating ring portion and several back toothed end cover portions connected to the outer side of the central insulating ring portion. The outer and inner sides of each back toothed end cover portion are respectively provided with back outer positioning protrusions and back inner positioning protrusions. The back outer positioning protrusions and the front outer positioning protrusions together constrain the outer end of the wire harness winding, and the back inner positioning protrusions and the front inner positioning protrusions together constrain the inner end of the wire harness winding.

3. An external rotor motor for driving an automotive cooling fan as described in claim 1 or 2, characterized in that: The terminal protection part includes a bottom protection plate and a side protection plate. The back of the bottom protection plate is connected to the back of the connecting rod, and the side protection plate has a clearance notch corresponding to the position of the connecting rod.

4. The external rotor motor for driving an automotive cooling fan as described in claim 3, characterized in that: A positioning ring is provided in the middle of the three mounting holes. The positioning ring is connected to the three mounting holes by connecting ribs. A positioning boss is provided on the corresponding conductive bracket mounting area and inserted into the positioning ring.

5. The external rotor motor for driving an automotive cooling fan as described in claim 4, characterized in that: The conductive bracket mounting area is a recessed area, and the conductive bracket is installed in the recessed area. The conductive bracket mounting area is provided with a positioning recessed area that corresponds to and matches the shape of the terminal protection part.

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