CN217788298U - Excitation protection device - Google Patents

Abstract

The invention relates to the field of power control and electric automobiles, and discloses an excitation protection device which comprises a shell, an excitation source, a piston and a conductive plate, wherein the excitation source, the piston and the conductive plate are arranged in the shell; the piston and the shell are integrally formed, and the conductive plate can be disconnected after the piston is separated from the shell under the driving of an excitation source. According to the excitation protection device, the piston and the shell are integrally formed, so that the number of parts is reduced, the assembly process is simplified, the assembly efficiency is improved, the production cost is reduced, the risk of neglected piston assembly is avoided, the yield of products is improved, and the reliability of circuit protection is improved.

Description

Excitation protection device

Technical Field

The invention relates to the field of electric control and electric automobiles, in particular to an excitation protection device with a piston and a shell integrally formed.

Background

The conventional fuse protector of the battery pack of the electric vehicle has a structure for quickly cutting off a circuit, namely an excitation protection device, and gradually expands the application range, and mainly overcomes the defects of large heat productivity, high power consumption, large volume and weight, limited current impact resistance, long breaking time and uncontrolled breaking process of the conventional fuse.

The general structure of the excitation protection device comprises a shell, wherein an excitation source, a piston and a conductive piece are sequentially arranged in the shell, and a pre-fracture is arranged on the conductive piece. The working principle is as follows: the excitation protection device is connected in series in the protection loop through the conductive piece, when the protection loop breaks down and needs to be disconnected, the control circuit controls the excitation source of the excitation protection device to trigger, the excitation source triggers to generate high-pressure gas, the piston is pushed to break the pre-fracture of the conductive piece, and a physical fracture is formed on the conductive piece, so that the purpose of quickly disconnecting the circuit is achieved.

The key action pieces of the excitation protection device are the piston and the current-conducting plate, the current-conducting plate is generally arranged in the shell in a penetrating mode, the piston is completely located inside the shell, the neglected loading piston is not easy to identify during assembly, or rework and reassembly are needed even if the neglected loading piston is scanned through visual identification, the cost is greatly increased, and the reliability of the excitation protection device is reduced due to the fact that the piston is easy to neglected loading.

Disclosure of Invention

The invention provides an excitation protection device which integrates a piston and a shell, wherein the piston is driven to be separated from the shell and then a conductive plate is disconnected during operation. The excitation protection device with the integrally formed piston and the shell reduces the number of parts, simplifies the assembly process, reduces the cost, avoids the risk of neglected piston installation, and improves the reliability of a protection circuit.

In order to achieve the technical purpose, the technical scheme provided by the invention is that the excitation protection device comprises a shell, an excitation source arranged in the shell, a piston and a conductive plate, wherein the piston can cut off the conductive plate under the driving of the excitation source; the piston and the shell are integrally formed, and the conductive plate can be disconnected after the piston is separated from the shell under the driving of an excitation source.

Preferably, a sight hole is provided in the housing wall, the impact end of the piston tail being located within the sight of the sight hole when the piston is in the initial position and the piston head being located within the sight of the sight hole when the piston is actuated.

Preferably, a baffle is arranged in front of the piston displacement, and a gap for the tail of the piston to pass through is reserved in the baffle or between the baffle and the inner wall of the shell.

Preferably, the piston comprises two opposite baffles, and a gap for the tail part of the piston to pass through is reserved between the two baffles.

Preferably, the two baffles are L-shaped, a gap is reserved between the two baffles and the inner wall of the shell, and the piston is positioned between the two baffles; the conducting plate is inserted in the gap between the baffle and the inner wall of the shell, and the conducting terminal of the conducting plate is positioned outside the shell.

Preferably, the housing is provided with an accommodating cavity for accommodating the conductive plate cut-off portion.

Preferably, a mounting opening is formed in one side of the housing, and the mounting opening is closed by an outer cover.

Preferably, the casing includes first casing and the second casing of mutual concatenation, and the excitation is located first casing, and piston, baffle, conducting plate, holding cavity are located the second casing respectively, and the installing port is seted up in second casing one side, and enclosing cover fixed connection seals the installing port on first casing and second casing.

Preferably, a through cavity is arranged in the first shell, and two ends of the first shell respectively extend outwards to form an annular structure; the excitation source is arranged in the cavity of the first shell, and an accommodating groove is formed between one end of the excitation source close to the piston and the first shell; the head of the piston is in an annular structure and protrudes out of the end face of the second shell, a limiting groove is formed between the piston and the second shell, and the bottom of the limiting groove is arranged at the integral joint of the piston and the second shell; when the first shell and the second shell are assembled, the annular structure of the first shell is clamped on the sealing contact surface in the limiting groove of the second shell, and the head of the piston is clamped in the accommodating groove formed by the first shell and the excitation source.

Preferably, the bottom of the limiting groove is provided with a sealing element.

Preferably, the contact end of the second housing and the first housing is respectively provided with a matching positioning groove or a positioning block, and when the first housing and the second housing are assembled, the positioning block is inserted into the positioning groove.

Preferably, the positioning groove and the positioning block, and the bottom of the second shell are respectively provided with a connecting and fixing hole; the outer cover is fixedly connected with the first shell and the second shell through one or combination of a plurality of fixing columns, pins, rivets or screws which penetrate through the connecting and fixing holes, and the mounting opening is sealed.

Preferably, a fixing post or a pin is integrally formed on the outer cover, and one end of the pin is forked.

Preferably, a plurality of reinforcing ribs are arranged on the outer cover, a sliding groove is formed between two adjacent reinforcing ribs, and one side of the piston is arranged in the sliding groove and can move along the sliding groove.

Preferably, a notch is formed in the outer cover, and a limit bump is formed at a position on one side of the second housing opposite to the notch of the outer cover, and the limit bump is located in the notch of the outer cover when the outer cover is assembled on the housing.

According to the excitation protection device, the piston and the shell are integrally formed, the current conducting plate is of a solid geometry structure, and the integrally formed baffle is added, so that the limiting effect on the current conducting plate is improved, the displacement of the piston is limited, the creepage distance is increased, and the installation reliability is improved; by adding the observation window, the state of the piston can be known at any time, and whether the excitation protection device fails or not is confirmed; the first shell and the second shell are in sealed contact by adding the positioning groove, the positioning block and other structures on the contact surface, the relative positions of the first shell and the second shell are fixed reliably, and the outer cover is fixed by adding the integrally formed fixing column and pin column on the outer cover without additionally adding parts such as screws and the like; the excitation protection device of the invention simplifies the assembly process, improves the assembly efficiency, reduces the production cost, avoids the risk of neglected piston installation, and improves the yield of products and the reliability of circuit protection while reducing the number of parts.

Drawings

Fig. 1 is a schematic view of the overall structure of the excitation protection device of the present invention.

Fig. 2 is a schematic diagram of the exploded structure of fig. 1.

Fig. 3 is a schematic view of the first housing structure.

Fig. 4 is a schematic view of another angle of the first housing.

Fig. 5 is a schematic cross-sectional structural view of the excitation protection device in interference fit with the excitation source.

Fig. 6 is a schematic cross-sectional structural view of the excitation protection device when the excitation source is in the injection molding process.

Fig. 7 is a schematic view of a second housing structure.

Fig. 8 is a schematic structural view of the second housing mounting opening side.

Fig. 9 is a schematic structural view of the outer side surface of the second housing on the opposite side of the mounting opening.

FIG. 10 is a schematic diagram of the outer side of the energizing protection device relative to the side of the outer cover before the piston is actuated.

FIG. 11 is a schematic view of the outer side of the energizing protection device relative to the outer cover after the piston is actuated.

Fig. 12 is a schematic diagram of a conductive plate structure.

FIG. 13 is a schematic view of the structure of the outer cover.

FIG. 14 is another schematic view of the outer cover.

FIG. 15 is another schematic view of the outer cover.

FIG. 16 is another schematic view of the outer cover.

FIG. 17 is a cross-sectional view of an excitation guard provided with a seal.

Detailed Description

According to the excitation protection device disclosed by the invention, as shown in fig. 1 and fig. 2, the excitation protection device comprises a first shell 1, an excitation source 2, a second shell 3, a conductive plate 4 and an outer cover 5, wherein the first shell 1, the second shell 3 and the outer cover 5 form a shell of the excitation protection device, and the conductive plate 4 is arranged in the shell in a penetrating manner. Wherein:

referring to fig. 3-6, a through cavity is formed inside the first housing 1, two ends of the cavity respectively extend out of two ends of the first housing main body to form an annular structure, one end of the cavity is a cavity top 101, the other end of the cavity is a cavity bottom 104, and the cavity top 101 and the cavity bottom 104 respectively protrude out of the first housing 1 main body. Ribs 102 are provided in the cavity.

The excitation source 2 is located in the cavity of the first housing 1, and the shape of the inner wall of the cavity contacting with the excitation source 2 has a limiting effect, that is, one end of the cavity top 101 is a contraction surface structure, so that the excitation source 2 is limited from entering the cavity top 101. The excitation source 2 is loaded into the cavity of the first shell 1 from one end of the bottom 104 of the cavity of the first shell 1, the excitation source 2 is in interference fit with the ribs 102 in the cavity, the excitation source 2 is fixedly arranged in the cavity of the first shell 1, and the trigger connector of the excitation source 2 is positioned in the top 101 of the cavity. The excitation source 2 can be limited and fixed in the cavity of the first housing 1 by means of interference, gluing or insert molding, and the like, and the embodiment is realized by adopting interference assembly, and refer to fig. 5. The excitation source 2 may also be formed as a unitary structure with the housing by insert molding, see fig. 6.

A plurality of positioning grooves 103 are formed in the main body of the first housing 1 on the outer periphery side of the cavity bottom 104 for assembling and positioning with the second housing 3, a connecting and fixing hole 105 for allowing the fixing column 501 of the outer cover 5 to pass through is arranged on the first housing 1, and the connecting and fixing hole 105 passes through the side wall of the positioning groove 103. A positioning notch 106 for positioning the outer cover 5 is formed on the side of the first housing 1 connected to one end of the fixing hole 105.

Referring to fig. 5, 7, 8 and 9, the second housing 3 is provided with a positioning block 301, a piston 302, a baffle plate 303 and a receiving cavity 304 for receiving the disconnected portion of the conductive plate. A cavity is arranged in the second shell 3, the cavity does not penetrate through the bottom of the second shell 3, a mounting opening is arranged on one side surface of the second shell 3, and the mounting opening is communicated with the cavity; the other sides of the second housing 3 opposite the mounting opening are closed sides. The piston 302 is located in the cavity and is integrally formed with the inner wall of the cavity of the second housing 3 through a joint 3023.

The piston 302 is composed of a piston head 3021 and a piston tail 3022. The top of the piston head 3021 protrudes from the top end surface of the main body of the second housing 3. The positioning block 301 is located outside the piston head 3021, a circle of limiting groove is formed between the piston head 3021 and the positioning block 301 in the second housing, and the limiting groove is opposite to the bottom 104 of the cavity of the first housing 1 and has a shape matching with the bottom. The bottom of the limiting groove is a part 3023 where the piston and the second shell are integrally connected. When the first shell and the second shell are assembled, the sealing element is arranged at the bottom of the limiting groove, the cavity bottom 104 is inserted into the limiting groove, the sealing element is pressed, and the contact surface of the first shell and the second shell is sealed.

The junction 3023 is also the interface of the piston head 3021 and the piston tail 3022. The joint 3023 is provided with a small thickness and a small strength, so that the driving of the piston to displace and damage the junction after the excitation source is triggered is facilitated, and the piston is separated from the second housing, but the strength of the joint needs to ensure that the piston cannot be separated from the second housing under the normal impact vibration working condition.

A sealing element 6, such as a sealing ring, can also be arranged at the bottom of the limiting groove, as shown in fig. 17, to realize the sealing of the contact surface between the first shell and the second shell. When the piston is disconnected with the integral connection part of the second shell, and the piston is displaced, the sealing element 6 can prevent high-pressure gas from leaking from the contact surface of the first shell and the second shell and the conductive plate cavity, so that the insulation between the excitation source driving loop and the conductive plate loop is ensured.

The piston head 3021 is cylindrical, the top of the piston head 3021 is provided with a groove for concentrating the acting force, when the second housing is assembled with the first housing, the top of the head of the piston 302 can extend into the cavity of the first housing 1, and one end of the excitation source 2 is located in the groove of the piston head, and meanwhile, the bottom 104 of the cavity of the first housing extends into the positioning groove between the piston head and the positioning block of the second housing 3, so as to form a nested sealing structure, further position and seal the contact surface between the first housing 1 and the second housing 3. The piston head may also be triangular, quadrangular or other polygonal shapes. The tail part 3022 of the piston is of an edge-shaped structure, and the lowest end of the piston is of a sharp edge structure serving as an impact end, so that force application is concentrated to one point when the piston moves, and the conductive plate is cut off more easily.

The positioning blocks 301 are correspondingly matched with the positioning grooves 103 of the first shell 1 and used for being assembled and positioned with the first shell, 4 positioning blocks are arranged in the example, correspondingly, the positioning grooves 103 in the first shell 1 are also arranged to be 4, and when the first shell is assembled with the second shell, the positioning blocks 301 extend into the positioning grooves 103 to realize positioning. The positioning block 301 is further provided with a connection fixing hole 3011, the connection fixing hole 3011 corresponds to the connection fixing hole 105 of the first housing 1, and when the first housing is assembled with the second housing, the connection fixing hole 3011 and the connection fixing hole 105 of the first housing 1 form a through hole for the fixing post 501 of the outer cover 5 to be inserted and fixed.

Baffle plates 303 are integrally formed below the bottom 3023 of the limiting groove and on two opposite sides of the piston tail 3022 respectively. Baffle 303 is L type structure, forms between baffle and the second casing 3 inner wall and supplies the electric conductive plate male clearance and cooperate the inner wall to spacing to the electric conductive plate, and the horizontal one end of baffle is located piston 302's displacement the place ahead, and is spacing to piston end position, and the relative interval setting of the horizontal one end of two baffles 303 forms the space that supplies piston afterbody 3022 to pass between two baffles 303. The baffle plate is used for pressing the conductive plate, so that the tilting of the disconnected side of the conductive plate due to impact force can be prevented after the piston disconnects the conductive plate; meanwhile, the baffle plate plays a role in isolating electric arcs and increasing creepage distance.

When the piston moves to the dead point, the baffle 303 limits the piston head 3021, and the piston tail 3022 penetrates through a gap formed between the two baffles to cut off the conductive plate. Compare in the direct spacing that regards as piston motion dead point with the conducting plate plane, set up the baffle between piston and conducting plate and can reduce the impact of piston to the casing lower part, the baffle also can play certain energy-absorbing effect. In addition, the baffle plate arranged between the piston and the conducting plate can further obstruct the conducting plate and the excitation source, and the insulating capability between the conducting plate loop and the excitation source trigger loop is improved.

The two baffles may also form a single baffle, but a gap must be left between the baffle and the inner wall of the housing, or in the baffle, through which the tail of the piston passes.

The inner walls of the second housing 3 at the outer sides of the baffle 303 are respectively provided with a stop projection 3041. An observation hole 305 and an observation hole 306 are provided in the other side wall of the second housing with respect to the mounting opening, and the observation holes are provided for the purpose of observing the moving state of the piston 302 and for the purpose of facilitating workability. Wherein the motion state of the piston 302 can be observed through the observation hole 306, before the action, as shown in fig. 10, the piston tail part 3022 can be observed through the observation hole 306, after the action, as shown in fig. 11, only the piston head part 3021 can be observed through the observation hole 306 due to the displacement of the piston, therefore, the combination of the observation hole 306 and the piston 302 can indicate whether the excitation protection device is actuated. A connecting and fixing hole 3042 for the fixing post 501 on the outer cover to pass through is also provided at one end of the bottom of the second housing 3. A side surface of the mounting opening of the second shell is provided with a limit bump 308, and the side surface of the limit bump 308 is an inclined surface.

The current conducting plate 4 is designed into a solid geometry structure which is bent for many times, thereby being beneficial to saving space and being convenient for limiting. Referring to fig. 12, the conductive plate 4 includes a conductive plate main body in a U shape and conductive terminals 404. The conductive terminals 404 are respectively located on two sides of the main body of the U-shaped conductive plate, and two side walls of the main body of the U-shaped conductive plate are bent at an angle of 90 degrees. The shape of the main body of the conductive plate matches the shape of the gap between the baffle 303 and the inner wall of the second housing. The outer side surfaces of the two side walls of the main body of the conductive plate are respectively provided with a limit bump 403, and the limit bumps 403 can be formed by punching.

The weak department 401 of disconnection has been preset just to the position of piston 302 afterbody tip in the current conducting plate main part, and the weak department 401 of disconnection is the structure of reduction intensity, and the concrete structure of the weak department of disconnection 401 is for "V" type groove structure of the current conducting plate width direction that link up that sets up in current conducting plate main part one side, sets up to the breach at "V" type groove both ends, makes the impact end of piston change from the weak department 401 of disconnection of current conducting plate and cuts off the current conducting plate. The rotating notch 402 is also preset on one side of the weak breaking point 401, so that after the conductive plate is cut off, the broken conductive plate part moves according to a preset track by taking the rotating notch as a circle center, and the specific structure of the rotating notch in the embodiment is a rectangular groove penetrating through the width direction of the conductive plate.

During assembly, when the main body of the conductive plate is inserted into the gap between the baffle 303 and the inner wall of the second housing from the mounting opening, referring to fig. 5 and fig. 6, the limit bump 403 on the conductive plate overcomes the limit of the limit bump 3041 and enters the gap between the limit bump 3041 and the other side wall, and the conductive plate is positioned and mounted by the limit of the limit bump 403 on the conductive plate by the limit bump 3041 and the limit of the baffle and the inner wall of the second housing on the conductive plate, so as to prevent the conductive plate from shaking and dropping out of the second housing. When the conductive plate is mounted in place, the weak breaking point 401 on the conductive plate is located in a gap formed between the two baffle plates 303 and directly faces the impact end of the tail part 3022 of the piston; the conductive terminals 404 are located outside both sides of the second housing 3. The receiving cavity 304 is located between the conductive plate and the bottom of the second housing, and after the conductive plate is broken, the conductive plate breaking portion can move into the receiving cavity 304 along the rotation notch.

After the first shell, the second shell, the excitation source, the conductive plate and the like are installed, referring to fig. 1 and fig. 2, the outer cover 5 is combined with the first shell and the second shell to form a relatively sealed shell, and the outer cover and the first shell and the second shell can be assembled by adopting connection and fixing modes such as fixed column hot melting or gluing, pin columns, rivets, screws, gluing, ultrasonic welding and the like. The specific structure of the outer cover 5 is shown in fig. 13-16.

One structure of the outer cover 5, as shown in fig. 13, four fixing posts 501 are arranged at the positions of the opposite connecting fixing holes on the contact surface where the outer cover 5 is assembled with the first casing and the second casing, the cross sections of the fixing posts can be circular, square, quincunx or other polygons, during assembly, the fixing posts 501 are hot-melted at the tail end after passing through the connecting fixing holes of the first casing and the second casing to realize integral connecting and fixing, or glue is dispensed in the surface of the fixing posts and the connecting fixing holes in advance and then assembled to realize adhesive fixing. A notch 506 is formed in the position of the outer cover 5 opposite to the position of the limit bump 308 of the second housing, and a corresponding inclined surface structure is arranged at the contact position of the notch 506 and the side surface of the limit bump 308. After the cover is assembled, the notch 506 covers at least three sides of the limiting bump 308, and is attached to the limiting bump, so that the positioning of the cover is further realized. Through the positioning fit of the notch 506 of the outer cover and the limiting bump 308 on the second shell, the impact force caused by left-right shaking on fixing pieces such as fixing columns, pins, rivets, screws and the like of the outer cover can be reduced.

In another structure of the outer cover 5, as shown in fig. 14, four pins 501 are arranged on the outer cover 5, the ends of the pins are split, a tool is used to clamp the split ends of the pins to fold the split ends during assembly, and after the pins 501 smoothly pass through the connecting and fixing holes of the first shell and the second shell, the split ends are naturally separated and cannot return, so that the integral connecting and fixing are realized, and glue can be dispensed on the pins at the non-split positions.

In another structure of the outer cover 5, as shown in fig. 15, two pins of the outer cover are removed to form two connecting and fixing holes 503 and two pins 501, the pins 501 are connected in the same manner as above, the connecting and fixing holes 503 correspond to the connecting and fixing positions which can be connected up and down, and the integral connecting and fixing are realized through rivets or screws.

In another structure of the outer cover 5, as shown in fig. 16, the outer cover is provided with connecting and fixing holes corresponding to the connecting and fixing holes of the first shell and the second shell, and the integral connecting and fixing is realized by rivets or screws.

The enclosing cover is relatively weak with first casing and second casing, so set up a plurality of groups strengthening rib 502 on enclosing cover and first casing and second casing complex contact surface, wherein, the enclosing cover equipment back that finishes, wherein forms the spout between two strengthening ribs 502, and piston afterbody one side is arranged in the spout, and is spacing through the spout, guarantees that the piston carries out vertical displacement along the spout structure after receiving the driving source drive, and can not the direction of deflecting.

And a limiting bump 505 is further arranged on the contact surface of the outer cover, and after the outer cover is assembled, the limiting bump 505 is clamped in a gap between the baffle where the conductive plate is arranged and the inner wall of the second shell to limit the position of the shell.

An assembling process:

firstly, an excitation source 2 is installed into the first shell 1 from one end of the cavity bottom 104 of the first shell 1, the excitation source 2 is in interference fit with the cavity of the first shell 1, and a trigger connector of the excitation source 2 is located in the cavity top 101; then, the first shell 1 and the second shell 3 are assembled together, one end of the excitation source 2 is positioned in a groove in the top of the piston head, the bottom 104 of the cavity of the first shell is clamped in a limiting groove of the second shell, and the positioning block 301 of the second shell 3 is clamped in a positioning groove 103 of the first shell 1, so that the contact surface of the first shell and the second shell is sealed; then, inserting the main body of the conductive plate into the gap between the baffle 303 of the second housing 3 and the inner wall of the second housing 3, so that the limit bumps 403 and 3041 are clamped to position the conductive plate; the outer cover 5 is covered, and the fixing posts 501 of the outer cover are inserted into the connecting and fixing holes which can be combined up and down for fixing.

The working principle is as follows:

the excitation source is triggered to generate high-pressure gas to provide driving force for the piston, the piston overcomes a connecting part integrally connected with the shell to separate the piston from the shell under the action of the high-pressure gas, the piston is driven to move, the conducting plate is disconnected from the weak disconnecting part 401 of the conducting plate, the tail part of the piston penetrates through a gap between two baffles to drive the disconnecting part of the conducting plate to rotate along the rotating notch 402 to enter the accommodating cavity 304, and when the piston moves to a dead point, the baffles limit the head part of the piston to stop moving.

Claims (15)

1. An excitation protection device comprises a shell, an excitation source arranged in the shell, a piston and a conductive plate, wherein the piston can disconnect the conductive plate under the driving of the excitation source; the piston and the shell are integrally formed, and the conductive plate can be disconnected after the piston is separated from the shell under the driving of an excitation source.

2. An excitation protection device according to claim 1 wherein a sight hole is provided in the housing wall, the impact end of the piston tail being located in the sight of said sight hole when the piston is in the home position and the piston head being located in the sight of said sight hole when the piston is actuated.

3. An excitation protector according to claim 1 characterised in that a shield is provided in front of the piston displacement, a gap being provided in the shield or between the shield and the inner wall of the housing for the tail of the piston to pass through.

4. Excitation protection means according to claim 3, comprising two oppositely disposed baffles, between which a gap is left through which the piston tail passes.

5. The excitation protection device of claim 4 wherein the two baffles are L-shaped, a gap is maintained between the two baffles and the inner wall of the housing, and the piston is located between the two baffles; the conducting plate is inserted in the gap between the baffle and the inner wall of the shell, and the conducting terminal of the conducting plate is positioned outside the shell.

6. Excitation protection means according to claim 1, wherein a receiving cavity is provided in the housing for receiving the conducting plate break.

7. The excitation protection device of any one of claims 1 to 6 wherein a mounting opening is provided in one side of the housing, said mounting opening being closed by an outer cover.

8. The excitation protection device of claim 7, wherein the housing comprises a first housing and a second housing which are spliced with each other, the excitation source is located in the first housing, the piston, the baffle plate, the conductive plate and the accommodating cavity are respectively located in the second housing, the mounting opening is formed in one side of the second housing, and the outer cover is fixedly connected to the first housing and the second housing to close the mounting opening.

9. The excitation protection device of claim 8, wherein the first housing is provided with a through cavity therein, and two ends of the first housing respectively extend outwards to form a ring structure; the excitation source is arranged in the cavity of the first shell, and an accommodating groove is formed between one end of the excitation source close to the piston and the first shell; the head of the piston is in an annular structure and protrudes out of the end face of the second shell, a limiting groove is formed between the piston and the second shell, and the bottom of the limiting groove is arranged at the integral joint of the piston and the second shell; when the first shell and the second shell are assembled, the annular structure of the first shell is clamped in the limiting groove of the second shell to seal the contact surface, and the head of the piston is clamped in the accommodating groove formed by the first shell and the excitation source.

10. The excitation protection device of claim 9 wherein the retaining groove bottom is provided with a seal.

11. The excitation protector as claimed in claim 8, wherein the second housing is provided with a matching positioning groove or positioning block at the end contacting the first housing, and the positioning block is inserted into the positioning groove when the first housing is assembled with the second housing.

12. The excitation protector as claimed in claim 11, wherein the positioning grooves and the positioning blocks, and the bottom of the second housing are respectively provided with connecting fixing holes; the outer cover is fixedly connected with the first shell and the second shell through one or combination of a plurality of fixing columns, pins, rivets or screws which penetrate through the connecting and fixing holes, and the mounting opening is sealed.

13. Excitation protection means according to claim 12, wherein a fixed post or pin is integrally formed on the outer cover, the pin being bifurcated at one end.

14. The excitation protector of claim 12 wherein a plurality of ribs are provided on said outer cover, wherein adjacent ribs define a channel therebetween, and wherein one side of the piston is disposed in the channel for displacement along the channel.

15. Excitation protection device according to claim 12, characterized in that a recess is provided in the outer cover, and a stop lug is provided on the second housing side at a position opposite to the recess in the outer cover, said stop lug being located in said recess in the outer cover when the outer cover is assembled on the housing.

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