CN108630857B

CN108630857B - Battery module casing for new energy automobile

Info

Publication number: CN108630857B
Application number: CN201810491063.XA
Authority: CN
Inventors: 阮忠诚; 张星光
Original assignee: Nanjing Ruiyi Electronic Technology Co Ltd
Current assignee: Huizhou Mingxin Precision Technology Co ltd
Priority date: 2018-05-21
Filing date: 2018-05-21
Publication date: 2021-06-25
Anticipated expiration: 2038-05-21
Also published as: CN108630857A

Abstract

The invention relates to the technical field of new energy automobiles, in particular to a battery module shell for a new energy automobile, which comprises an upper shell, a lower shell, a heat dissipation mechanism, a sealing mechanism, screws, a joint, a fixing mechanism, a connecting mechanism and a heat dissipation plate, wherein the upper shell and the lower shell are fixedly connected through the screws, and the sealing mechanism is arranged, so that the connection stability can be improved, and meanwhile, the sealing performance is improved. Battery module is fixed through fixed establishment earlier on the casing down, and block fixed connection is convenient for follow the dismantlement of trading between fixed establishment and the casing down. The battery modules in the plurality of fixing structures on the lower shell are connected through the connecting mechanism, so that after the single module is detached, other battery modules can be communicated with each other and used. Go up the casing and be equipped with heat dissipation mechanism down between the casing, can directly blow the heat dissipation to the battery module to utilize the heating panel to dispel the heat, effectively dispel the heat.

Description

Battery module casing for new energy automobile

Technical Field

The invention relates to the technical field of new energy automobiles, in particular to a battery module shell for a new energy automobile.

Background

The new energy automobile adopts unconventional automobile fuel as a power source (or adopts conventional automobile fuel and a novel vehicle-mounted power device), integrates advanced technologies in the aspects of power control and driving of the automobile, and forms an automobile with advanced technical principle, new technology and new structure.

In the new energy automobile battery pack installation fixing process, the battery module and the shell are fixedly connected, the battery module is not easy to detach and replace, and after the single battery module is detached, the whole battery module cannot be electrified. The battery module is not good in sealing performance and heat dissipation performance, and the common problems of the existing battery modules are solved. In view of this, the invention provides a battery module housing for a new energy automobile, which has the following characteristics:

(1) according to the battery module shell for the new energy automobile, the upper shell and the lower shell are fixedly connected through the screws, and the sealing mechanism is arranged, so that the connection stability can be improved, and meanwhile, the sealing performance is improved.

(2) According to the battery module shell for the new energy automobile, the battery module on the lower shell is fixed through the fixing mechanism, and the fixing mechanism is fixedly connected with the lower shell in a clamping manner, so that the battery module shell is convenient to replace and disassemble.

(3) According to the battery module shell for the new energy automobile, the battery modules in the plurality of fixing structures on the lower shell are connected through the connecting mechanism, so that after a single module is dismounted, other battery modules can be mutually communicated and used.

(4) According to the battery module shell for the new energy automobile, the heat dissipation mechanism is arranged between the upper shell and the lower shell, so that air can be directly blown to dissipate heat of the battery module, and heat can be dissipated by the heat dissipation plate, so that heat dissipation is effectively achieved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a battery module shell for a new energy automobile. Battery module is fixed through fixed establishment earlier on the casing down, block fixed connection, the change dismantlement of being convenient for between fixed establishment and the casing down. The battery modules in the plurality of fixing structures on the lower shell are connected through the connecting mechanism, so that after the single module is detached, other battery modules can be communicated with each other and used. Go up the casing and be equipped with heat dissipation mechanism down between the casing, can directly blow the heat dissipation to the battery module to utilize the heating panel to dispel the heat, effectively dispel the heat.

The technical scheme adopted by the invention for solving the technical problems is as follows: a battery module shell for a new energy automobile comprises an upper shell, a lower shell, a heat dissipation mechanism, a sealing mechanism, a screw, a joint, a fixing mechanism, a connecting mechanism and a heat dissipation plate, wherein the upper shell is fixedly connected to the lower shell through the screw; the upper shell and the lower shell are provided with the sealing mechanism, the sealing mechanism comprises a sealing plate and a sealing washer, the sealing plate is arranged on the bottom surface of the upper shell and is clamped and connected in a second clamping groove on the lower shell, and the sealing washer is arranged on the lower shell and positioned on the inner side of the sealing plate; the joint is arranged at one end of the side wall of the lower shell; the fixing mechanism is arranged on the lower shell and positioned on the inner side of the sealing washer and comprises a second fixing shell and a battery, the second fixing shell is clamped and connected in a first clamping groove in the lower shell, and the battery is clamped and arranged in the second fixing shell; the lower shell is provided with the connecting mechanism, the connecting mechanism comprises a first expansion plate, a spring, a first copper block, a second partition plate, a first copper connecting plate, a second expansion plate, a third copper connecting plate, a fourth copper connecting plate and a third expansion plate, the inner side wall of the first clamping groove on the lower shell is clamped with the first expansion plate in an expansion and contraction way, the third expansion plate is arranged on the other symmetrical inner side wall in the second clamping groove on the lower shell, the inner side wall of the other first clamping groove adjacent to the first clamping groove on the lower shell, which is close to the first expansion plate, is in expansion and contraction connection with the second expansion plate, the bottoms of the first expansion plate, the second expansion plate and the third expansion plate are all connected with the first copper block, the second copper block is arranged in the lower shell, and the spring is sleeved on the first copper block and the second copper block, one side of the first expansion plate is connected with one end of the first copper connecting plate, the other end of the first copper connecting plate is connected with one end of the second copper connecting plate in a contact manner, the other end of the second copper connecting plate is connected with one side of the second expansion plate, the other side of the first expansion plate is connected with one end of the third copper connecting plate, the other end of the third copper connecting plate is connected with one end of the fourth copper connecting plate in a contact manner, and the other end of the fourth copper connecting plate is connected with one side of the third expansion plate in a contact manner; the heat dissipation mechanism is arranged on the lower shell and the upper shell and comprises a first fixed shell, a motor, a rotating column, a fan and a first partition plate, the first fixed shell is arranged on the top surface of the lower shell, the motor is arranged in the first fixed shell, the rotating column is sleeved on a rotating shaft of the motor, the fan is arranged on the rotating column and is positioned in an air outlet on the first fixed shell, and the first partition plate is arranged on the upper shell; the bottom of the second fixed shell on the lower shell is provided with the heat dissipation plate.

Specifically, the side view of going up the casing is rectangle and right trapezoid's polygon integrated configuration, and this right trapezoid's height is greater than first fixed casing's height realizes the first fixed casing of effective fixed mounting.

Specifically, the sealing plate is of a hollow rectangular structure, at least four screws are arranged and are arranged at four corners of the top surface of the upper shell, and the stability of connection and fixation between the upper shell and the lower shell is improved.

Specifically, on the lower casing first draw-in groove is equipped with a plurality ofly, in the second fixed casing the battery is equipped with a plurality ofly, and a plurality of the battery set up side by side in the second fixed casing, and a plurality of establish ties between the battery, realize increasing the electric quantity deposit of battery.

Specifically, first copper link the board with be "L" shape structure that the size equals between the second copper link the board, the third copper link the board with the fourth copper link the board and is the integrated configuration of two "L" shaped plates, just the width that the third copper links the board is greater than the width that the fourth copper links the board, the third copper link the board with the fourth copper links the bending part between the board and does not contact each other, and when realizing the expansion plate compression, first copper links each other and the second copper links each other and does not contact each other between the board, and the third copper links each other and does not contact each other between board and the fourth copper.

Specifically, first baffle with the air outlet is equipped with a plurality ofly, first baffle with the air outlet one-to-one sets up, just first baffle with conflict between the top surface of casing down and be connected, realize cutting apart the group battery of different groups, realize separately dispelling the heat, the steam that forms each other does not interfere with each other, improves the radiating efficiency.

Specifically, the top view of the sealing washer is of a hollow rectangular structure, the cross section of the sealing washer is of a polygonal structure with the upper end being rectangular and the lower end being triangular, and the sealing performance of the sealing washer is improved.

Specifically, first expansion plate the second expansion plate with the third expansion plate is outstanding the part of the inside wall of first draw-in groove is prismoid structure, just first expansion plate the second expansion plate reaches the outstanding length of third expansion plate with first copper billet and distance between the second copper billet equals, the maximum compression distance of spring is greater than first copper billet with distance between the second copper billet tries down the fixed casing of second with effectual block is fixed down between the casing, realizes the effective contact connection between the copper billet after realizing the compression expansion plate simultaneously.

The invention has the beneficial effects that:

Drawings

The invention is further illustrated with reference to the following figures and examples.

Fig. 1 is a schematic structural diagram of a battery module housing for a new energy vehicle according to a preferred embodiment of the present invention;

FIG. 2 is a top partial cross-sectional view of the lower housing shown in FIG. 1;

FIG. 3 is a side cross-sectional view of the upper and lower housings shown in FIG. 1;

fig. 4 is a top cross-sectional view of the upper housing shown in fig. 1.

In the figure: 1. the heat dissipation device comprises an upper shell, a lower shell, a first clamping groove, a second clamping groove, a heat dissipation mechanism, a first fixing shell, a first sealing washer, a second sealing washer, a third sealing washer, a fourth sealing washer, a heat dissipation mechanism, a heat dissipation plate, a motor, a rotating column, a fan, a first partition plate, a sealing washer, a sealing mechanism, a sealing plate, a sealing washer, 5, a screw, a connector, a fixing mechanism, a second fixing shell, a.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

As shown in fig. 1, the battery module housing for a new energy vehicle according to the present invention includes an upper housing 1, a lower housing 2, a heat dissipation mechanism 3, a sealing mechanism 4, a screw 5, a connector 6, a fixing mechanism 7, a connecting mechanism 8, and a heat dissipation plate 9, wherein the upper housing 1 is fixedly connected to the lower housing 2 through the screw 5; the sealing mechanism 4 is arranged on the upper shell 1 and the lower shell 2, the sealing mechanism 4 comprises a sealing plate 41 and a sealing washer 42, the sealing plate 41 is arranged on the bottom surface of the upper shell 1, the sealing plate 41 is clamped and connected in a second clamping groove 2b on the lower shell 2, and the sealing washer 42 is arranged on the lower shell 2 and positioned on the inner side of the sealing plate 41; one end of the side wall of the lower shell 2 is provided with the joint 6; the fixing mechanism 7 is arranged on the lower shell 2 and located on the inner side of the sealing washer 42, the fixing mechanism 7 comprises a second fixing shell 71 and a battery 72, the second fixing shell 71 is connected to the first clamping groove 2a on the lower shell 2 in a clamping manner, and the battery 72 is arranged in the second fixing shell 71 in a clamping manner; the lower shell 2 is provided with the connecting mechanism 8, the connecting mechanism 8 comprises a first expansion plate 81, a spring 82, a first copper block 83, a second copper block, a second clapboard 85, a first copper connecting plate, a second expansion plate 88, a third copper connecting plate 89, a fourth copper connecting plate 89A and a third expansion plate 89B, one inner side wall of the first clamping groove 2a on the lower shell 2 is connected with the first expansion plate 81 in a clamping and telescopic manner, the other symmetrical inner side wall in the second clamping groove 2B on the lower shell 2 is provided with the third expansion plate 89B, the inner side wall in the other first clamping groove 2a adjacent to the first clamping groove 2a on the lower shell 2 and close to the first expansion plate 81 is connected with the second expansion plate 88 in a telescopic manner, the bottoms of the first expansion plate 81, the second expansion plate 88 and the third expansion plate 89B are all connected with the first copper block 83, the second copper block is arranged in the lower shell 2, the spring 82 is sleeved on the first copper block 83 and the second copper block, one side of the first expansion plate 81 is connected with one end of the first copper connecting plate 86, the other end of the first copper connecting plate 86 is connected to one end of the second copper connecting plate 87 in a contact manner, the other end of the second copper connecting plate 87 is connected to one side of the second expansion plate 88, the other side of the first expansion plate 81 is connected with one end of the third copper connecting plate 89, the other end of the third copper connecting plate 89 is connected to one end of the fourth copper connecting plate 89A in a contact manner, and the other end of the fourth copper connecting plate 89A is connected to one side of the third expansion plate 89B in a contact manner; the heat dissipation mechanism 3 is arranged on the lower shell 2 and the upper shell 1, the heat dissipation mechanism 3 includes a first fixed shell 31, a motor 32, a rotating column 33, a fan 34 and a first partition plate 35, the first fixed shell 31 is mounted on the top surface of the lower shell 2, the motor 32 is mounted in the first fixed shell 31, the rotating column 33 is sleeved on a rotating shaft of the motor 32, the rotating column 33 is provided with the fan 34, the fan 34 is positioned in an air outlet 31a on the first fixed shell 31, and the first partition plate 35 is arranged on the upper shell 1; the heat dissipation plate 9 is disposed on the lower case 2 at the bottom of the second fixed case 71.

Specifically, as shown in fig. 1 and 3, the side view of the upper case 1 of the battery module case for a new energy vehicle according to the present invention is a polygonal combined structure of a rectangle and a right trapezoid, and the height of the right trapezoid is greater than that of the first fixing case 31, so that the first fixing case 31 can be effectively fixed and mounted.

Specifically, as shown in fig. 1, the sealing plate 41 of the battery module housing for the new energy automobile has a hollow rectangular structure, at least four screws 5 are provided, and the four screws 5 are provided at four corners of the top surface of the upper housing 1, so as to increase the stability of connection and fixation between the upper housing 1 and the lower housing 2.

Specifically, as shown in fig. 1, a plurality of first card slots 2a are provided on the lower housing 2 of the battery module housing for a new energy vehicle, a plurality of batteries 72 are provided in the second fixed housing 71, the plurality of batteries 72 are arranged in the second fixed housing 71 side by side, and the plurality of batteries 72 are connected in series, so that the electric quantity reserve of the batteries 72 is increased.

Specifically, as shown in fig. 1 and fig. 2, the first copper connecting plate 86 and the second copper connecting plate 87 of the battery module housing for a new energy vehicle according to the present invention are in an L-shaped structure with an equal size, the third copper connecting plate 89 and the fourth copper connecting plate 89A are both in a combined structure of two L-shaped plates, the width of the third copper connecting plate 89 is greater than the width of the fourth copper connecting plate 89A, the bent portions of the third copper connecting plate 89 and the fourth copper connecting plate 89A are not in contact with each other, when the expansion plate is compressed, the first copper connecting plate 86 and the second copper connecting plate 87 are not in contact with each other, and the third copper connecting plate 89 and the fourth copper connecting plate 89A are not in contact with each other.

Specifically, as shown in fig. 3 and 4, a plurality of first partition plates 35 and a plurality of air outlets 31a are arranged on the battery module casing for a new energy automobile, the first partition plates 35 and the air outlets 31a are arranged in a one-to-one correspondence, and the first partition plates 35 are in interference connection with the top surface of the lower casing 2, so that different groups of battery packs are separated, heat dissipation is achieved separately, hot air formed between the battery packs does not interfere with each other, and heat dissipation efficiency is improved.

Specifically, as shown in fig. 3, the top view of the sealing gasket 42 of the battery module housing for a new energy automobile according to the present invention is a hollow rectangular structure, and the cross section of the sealing gasket 42 is a polygonal structure with a rectangular upper end and a triangular lower end, so as to increase the sealing performance of the sealing gasket 42.

Specifically, as shown in fig. 3, the portions of the first expansion plate 81, the second expansion plate 88 and the third expansion plate 89B of the battery module housing for a new energy vehicle protruding out of the inner side wall of the first slot 2a are in a frustum pyramid structure, the protruding lengths of the first expansion plate 81, the second expansion plate 88 and the third expansion plate 89B are equal to the distance between the first copper block 83 and the second copper block, the maximum compression distance of the spring 82 is greater than the distance between the first copper block 83 and the second copper block, effective clamping and fixing between the second fixed housing 71 and the lower housing 2 are tried, and effective contact connection between the copper blocks is realized after the expansion plates are compressed.

Go up between casing 1 and the lower casing 2 through screw 5 fixed connection, and be equipped with sealing mechanism 4 between last casing 1 and the lower casing 2 and realize sealing connection. Be equipped with fixed establishment 7 and coupling mechanism 8 on casing 2 down, realize utilizing the regulation mechanism can install a plurality of group battery, and conveniently tear open and trade, utilize coupling mechanism 8 to realize when dismantling one of them group battery, do not influencing the continuation of other group batteries and use. And then the whole upper shell 1 and the whole lower shell 2 are provided with the heat dissipation mechanisms 3, so that the effective and direct heat dissipation of the battery pack is realized. The method specifically comprises the following steps:

(1) the battery 72 is mounted in the second fixed case 71, and then the entire second fixed case 71 is mounted in the first card slot 2a in the lower case 2, compressing the first expansion plate 81, the second expansion plate 88, and the third expansion plate 89B. The first copper block 83 and the second copper block are brought into contact with each other, the first copper link plate 86 and the second copper link plate 87 are disconnected, and the third copper link plate 89 and the fourth copper link plate 89A are disconnected. And normal connection of the whole circuit is realized.

(2) Then, the screw 5 is used for fixedly connecting the upper shell 1 and the lower shell 2, before the screw 5 is fixedly connected, a sealing gasket 42 is arranged between the upper shell 1 and the lower shell 2, and the sealing plate 41 is clamped and connected in the second clamping groove 2b, so that effective sealing is realized.

(3) After the circuit is connected, the battery 72 may generate heat during use, which may affect the use of the battery 72 for a long time. At this time, the motor 32 is turned on, and the rotating column 33 is driven to rotate by the motor 32, so that the rotating column 33 is driven to rotate, and the battery 72 is continuously blown. Utilize first baffle 35 to make and blow to different group batteries, do not exert an influence each other, improve the radiating efficiency.

(4) Then when the battery 72 needs to be maintained and replaced, after one of the second fixing shells 71 is removed, the expansion plate is restored by the spring 82, the first copper block 83 and the second copper block are separated, meanwhile, the first copper connecting plate 86 and the second copper connecting plate 87 are in contact connection, the third copper connecting plate 89 and the fourth copper connecting plate 89A are in contact connection, connection between the copper blocks is disconnected, connection between the copper connecting plates is connected, connection between other battery packs is continuously achieved, and after one battery pack is removed, use of other battery packs is not affected.

The upper shell 1 and the lower shell 2 are fixedly connected through the screws 5, and the sealing mechanism 4 is arranged, so that the connection stability can be improved, and meanwhile, the sealing performance is improved. Battery module is fixed through fixed establishment 7 earlier on the casing 2 down, and block fixed connection is convenient for change dismantlement between fixed establishment 7 and the casing 2 down. The battery modules in the plurality of fixed structures on the lower shell 2 are connected through the connecting mechanism 8, so that after the single module is dismounted, other battery modules can be communicated with each other and used. Go up and be equipped with heat dissipation mechanism 3 between casing 1 and the lower casing 2, can directly blow the heat dissipation to the battery module to utilize heating panel 9 to dispel the heat, effectively dispel the heat.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the embodiments and descriptions given above are only illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a battery module casing for new energy automobile which characterized in that: the heat dissipation device comprises an upper shell (1), a lower shell (2), a heat dissipation mechanism (3), a sealing mechanism (4), a screw (5), a joint (6), a fixing mechanism (7), a connecting mechanism (8) and a heat dissipation plate (9), wherein the upper shell (1) is fixedly connected to the lower shell (2) through the screw (5); the sealing mechanism (4) is arranged on the upper shell (1) and the lower shell (2), the sealing mechanism (4) comprises a sealing plate (41) and a sealing washer (42), the sealing plate (41) is arranged on the bottom surface of the upper shell (1), the sealing plate (41) is clamped and connected in a second clamping groove (2b) on the lower shell (2), and the sealing washer (42) is arranged on the lower shell (2) and positioned on the inner side of the sealing plate (41); one end of the side wall of the lower shell (2) is provided with the joint (6); wherein,

the fixing mechanism (7) is arranged on the lower shell (2) and located on the inner side of the sealing washer (42), the fixing mechanism (7) comprises a second fixing shell (71) and a battery (72), the second fixing shell (71) is connected in a clamping manner in the first clamping groove (2a) on the lower shell (2), and the battery (72) is arranged in the second fixing shell (71) in a clamping manner; the lower shell (2) is provided with the connecting mechanism (8), the connecting mechanism (8) comprises a first expansion plate (81), a spring (82), a first copper block (83), a second copper block, a second partition plate (85), a first copper connecting plate, a second expansion plate (88), a third copper connecting plate (89), a fourth copper connecting plate (89A) and a third expansion plate (89B), the first expansion plate (81) is clamped and telescopically connected on one inner side wall of the first clamping groove (2a) on the lower shell (2), the third expansion plate (89B) is arranged on the other symmetrical inner side wall in the second clamping groove (2B) on the lower shell (2), the second expansion plate (88) is telescopically connected on the inner side wall close to the first expansion plate (81) in the other first clamping groove (2a) adjacent to the first clamping groove (2a) on the lower shell (2), first expansion plate (81), second expansion plate (88) and the bottom of third expansion plate (89B) all is connected with first copper billet (83), the second copper billet is located in lower casing (2), first copper billet (83) with cup jointed on the second copper billet spring (82), one side of first expansion plate (81) is connected with the one end of first copper even board (86), the other end contact of first copper even board (86) connect in the one end of second copper even board (87), the other end of second copper even board (87) connect in one side of second expansion plate (88), the opposite side of first expansion plate (81) is connected with the one end of third copper even board (89), the other end contact of third copper even board (89) connect in the one end of fourth copper even board (89A), the other end contact of fourth copper even board (89A) connect in the one side contact of third expansion plate (89B) (ii) a Wherein,

the heat dissipation mechanism (3) is arranged on the lower shell (2) and the upper shell (1), the heat dissipation mechanism (3) comprises a first fixed shell (31), a motor (32), a rotating column (33), a fan (34) and a first partition plate (35), the first fixed shell (31) is installed on the top surface of the lower shell (2), the motor (32) is installed in the first fixed shell (31), the rotating column (33) is sleeved on a rotating shaft of the motor (32), the fan (34) is arranged on the rotating column (33), the fan (34) is located in an air outlet (31a) in the first fixed shell (31), and the first partition plate (35) is arranged on the upper shell (1); the heat dissipation plate (9) is arranged at the bottom of the second fixed shell (71) on the lower shell (2).

2. The battery module casing for the new energy automobile of claim 1, characterized in that: the side view of the upper shell (1) is a polygonal combined structure of a rectangle and a right trapezoid, and the height of the right trapezoid is greater than that of the first fixed shell (31).

3. The battery module casing for the new energy automobile of claim 1, characterized in that: the sealing plate (41) is of a hollow rectangular structure, at least four screws (5) are arranged, and the four screws (5) are arranged at four corners of the top surface of the upper shell (1).

4. The battery module casing for the new energy automobile of claim 1, characterized in that: the first clamping grooves (2a) on the lower shell (2) are provided with a plurality of batteries, the batteries (72) in the second fixed shell (71) are provided with a plurality of batteries (72), the batteries (72) are arranged in the second fixed shell (71) side by side, and the batteries (72) are connected in series.

5. The battery module casing for the new energy automobile of claim 1, characterized in that: the first copper connecting plate (86) and the second copper connecting plate (87) are in L-shaped structures with equal size, the third copper connecting plate (89) and the fourth copper connecting plate (89A) are of combined structures of two L-shaped plates, the width of the third copper connecting plate (89) is larger than that of the fourth copper connecting plate (89A), and bent parts between the third copper connecting plate (89) and the fourth copper connecting plate (89A) are not in contact with each other.

6. The battery module casing for the new energy automobile of claim 1, characterized in that: first baffle (35) with air outlet (31a) are equipped with a plurality ofly, first baffle (35) with air outlet (31a) one-to-one sets up, just first baffle (35) with contradict between the top surface of casing (2) down and be connected.

7. The battery module casing for the new energy automobile of claim 1, characterized in that: the top view of the sealing washer (42) is a hollow rectangular structure, and the cross section of the sealing washer (42) is a polygonal structure with the upper end being rectangular and the lower end being triangular.

8. The battery module casing for the new energy automobile of claim 1, characterized in that: first expansion plate (81), second expansion plate (88) and third expansion plate (89B) are outstanding the part of the inside wall of first draw-in groove (2a) is the terrace with edge structure, just first expansion plate (81), second expansion plate (88) and the outstanding length of third expansion plate (89B) with first copper billet (83) and distance between the second copper billet equals, the biggest compression distance of spring (82) is greater than first copper billet (83) with distance between the second copper billet.