Semi-solid-state battery pack with square aluminum shell

Abstract

The invention relates to the technical field of square aluminum shell battery packs, in particular to a square aluminum shell semi-solid battery pack which comprises a battery box frame, a square battery pack inner core is arranged in the battery box frame, and isolated aluminum plate assemblies are arranged on four vertical side faces between the battery box frame and the battery pack inner core. The aluminum plate assembly comprises a hard plate square frame in a square plate frame shape, square aluminum plates distributed in the middle of the hard plate square frame, a row of limiting units making contact with the edges of the square aluminum plates and a column square frame making contact with the limiting units in a transmission mode, and adjustment and control after deformation of the square aluminum plates can cause power failure of the battery pack. According to the square aluminum plate deformation monitoring device, the safety problem caused by electrification of an overheated square aluminum plate or a damaged square aluminum plate is avoided, deformation of the square aluminum plate is monitored timely and sensitively by arranging a plurality of limiting units on the peripheral edge of the square aluminum plate, any limiting unit monitors deformation of the square aluminum plate, and subsequent transmission can cause final outage.

Description

Technical Field

[0001] The invention relates to the technical field of square aluminum shell battery packs, in particular to a square aluminum shell semi-solid battery pack. Background Art

[0002] Aluminum shells are prone to deformation, which is mainly due to the characteristics of aluminum materials and the problems that may be encountered during processing. Aluminum has low rigidity and a large thermal expansion coefficient, which means that aluminum shells are easily affected by thermal and mechanical stresses, resulting in deformation. Common forms of deformation include bending, bulging and depression. The outer shell of the square aluminum shell semi-solid battery pack is made of aluminum material. The weight of aluminum shell batteries is lighter than that of steel shell batteries, which helps to reduce the weight of the entire battery pack. At the same time, aluminum has good thermal conductivity, which helps the battery to quickly dissipate heat, extend the battery life and improve safety. Aluminum shell batteries also have excellent corrosion resistance and can effectively intercept corrosive materials leaked from the battery.

[0003] The aluminum plate of the battery pack shell will also undergo significant volume changes when the temperature changes. In actual applications, due to the large temperature difference, the aluminum plate will expand when heated or contract when cooled, resulting in obvious deformation. Based on the solution to the thermal expansion deformation and impact deformation of the aluminum shell, the present invention provides a square aluminum shell semi-solid battery pack. Summary of the invention

[0004] The object of the present invention is to provide a square aluminum shell semi-solid battery pack to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a square aluminum shell semi-solid battery pack, comprising a battery box frame, a battery pack core with a square appearance is arranged in the battery box frame, and an isolated aluminum plate assembly is arranged at the four vertical side positions between the battery box frame and the battery pack core, and the aluminum plate assembly includes a hard plate frame in the shape of a square plate frame, square aluminum plates distributed in the hard plate frame, a row of limit units that are in contact with each edge of the square aluminum plate, and a column frame that is in contact with all the limit units for transmission, the column frames are distributed in parallel on one side of the hard plate frame, and a heat dissipation opening is provided on the battery box frame shell on one side of the square aluminum plate. Plate hole, a square frame is arranged flatly above the inner core of the battery pack, a plurality of groups of conductive metal sheets are fixed in the middle of the square frame, and the conductive metal sheets realize current transmission by contacting with the ends of the electrode sheets on the inner core of the battery pack, four corners of the square frame are connected with spring groups, two hard plate frames at the corners of the inner core of the battery pack are vertically fixed to form an L-shaped vertical plate, and the spring group is arranged on the L-shaped vertical plate, and a control device is connected to the upper end of each column frame, and the control device makes the square frame rise by pushing the frame frame on the square frame upward, and the square frame makes the electrode sheet ends and the wire metal sheets of the inner core of the battery pack disconnected and separated by rising.

[0006] The limiting unit supports one side edge of the square aluminum plate, and the other side edge of the square aluminum plate is also integrally connected with a square frame thin plate, and the limiting unit and the back plate fixed on the hard plate square frame cooperate to clamp the square frame thin plate of the square aluminum plate.

[0007] The spring group includes an interception body fixed on the hard plate frame, a corner rod fixedly connected to the square frame, and a spring sleeved on the corner rod. The corner rod slides through a through hole opened on the interception body, and the spring is supported between the square frame and the interception body.

[0008] The limiting unit includes a rubber plate padded between the hard plate frame and the square aluminum plate, a unit straight plate distributed on one side of the rubber plate, a limiting plate seat for restraining the unit straight plate, a booster spring connected between the limiting plate seat and the unit straight plate, and a transmission group for contact transmission with the unit straight plate. The column frame slides through a through hole opened at one end of the limiting plate seat by means of a vertically fixed directional column.

[0009] The edge of the square frame sheet on the square aluminum plate is inserted into the groove opened at one end of the rubber plate, and the other end of the rubber plate is inserted into the plate groove opened on the hard plate square frame. The unit straight plate is provided with a convex block to contact the outer edge of the square aluminum plate.

[0010] The limit plate seat is fixed on the hard plate frame, the unit straight plate slides through the plate hole opened on the limit plate seat, one end of the booster spring is fixed on the unit straight plate, and the other end is fixed on the limit plate seat.

[0011] The transmission group includes a sub-plate frame with one end fixed on the limit plate seat, a reversing seat padded between the unit straight plate and the column square frame, and a pressure cover spring sheet supporting the reversing seat, one end of the pressure cover spring sheet is fixed on the sub-plate frame, the reversing seat includes a concave block and a slider fixed on one side of the concave block, a semi-cylinder is arranged on the unit straight plate to be inserted into the concave block of the reversing seat, and the slider of the reversing seat passes through the square hole opened on the sub-plate frame and contacts with the column square frame.

[0012] The control device includes an L-shaped push-pull plate fixed on the column frame, a flat plate group connected to one end of the L-shaped push-pull plate, and a top frame supporting the flat plate group. The end of the top frame is fixed on the hard plate frame, and the flat plate group and the frame are in contact transmission.

[0013] The plate group includes an L-shaped plate in contact with the square frame, a U-shaped spring piece fixedly connected between the L-shaped plate and the L-shaped push-pull plate, a piston column arranged on the L-shaped plate, a cylinder barrel with one end slidingly sleeved on the piston column, and a spring piece door blocking the port at the other end of the cylinder barrel. The top frame is provided with two symmetrical concave blocks to clamp the L-shaped plate.

[0014] One end of the L-shaped plate pushes the frame of the square frame by setting an inclined surface, and a triangular plate is set on the L-shaped plate to support and fix the piston column. The shrapnel door includes a disk body and a C-shaped shrapnel fixed on one side of the disk body, and one end of the C-shaped shrapnel is fixed on the top frame, and a fine air replenishing hole is opened in the middle of the disk body of the shrapnel door.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention further controls the power on and off of the battery pack by monitoring the thermal expansion deformation or impact deformation of the square aluminum plate. The adjustment control after the deformation of the square aluminum plate will cause the battery pack to be powered off, avoiding the safety problems caused by the power on of the overheated square aluminum plate or the damaged square aluminum plate. By arranging multiple limit units around the edges of the square aluminum plate, the deformation of the square aluminum plate can be monitored in a timely and sensitive manner. If any limit unit detects the deformation of the square aluminum plate, subsequent transmission will cause the final power off.

[0016] 2. The present invention can effectively avoid power outages caused by vibration by setting a delay mechanism in the flat plate group. Only the deformation of the square aluminum plate will cause power outages. The temporary vibration impact of the square aluminum plate ends before the L-shaped flat plate makes an effective translation, and will not cause the subsequent square frame to rise, thereby avoiding power outages and ensuring stable charging and discharging of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention.

[0018] Figure 2 Schematic diagram of the aluminum plate assembly structure.

[0019] Figure 3 Schematic diagram of the battery box frame structure.

[0020] Figure 4 Schematic diagram of the control device location.

[0021] Figure 5 It is a schematic diagram of the spring group structure.

[0022] Figure 6 This is a schematic diagram of the square frame structure.

[0023] Figure 7 This is a schematic diagram of the back panel position.

[0024] Figure 8 It is a schematic diagram of the limit unit structure.

[0025] Fig. 9 A schematic diagram of the transfer group structure.

[0026] Fig.10 This is a schematic diagram of the unit straight plate position.

[0027] Fig.11This is a schematic diagram of the control structure.

[0028] Fig.12 This is a schematic diagram of the position of the L-shaped sliding plate.

[0029] Fig.13 It is a schematic diagram of the flat plate group structure.

[0030] In the figure: battery box frame 1, battery pack inner core 2, aluminum plate assembly 3, hard plate frame 4, square aluminum plate 5, limit unit 6, column frame 7, square frame 8, spring group 9, control device 10, back plate 11, interception body 12, spring 13, corner rod 14, rubber plate 15, booster spring 16, transmission group 17, limit plate seat 18, unit straight plate 19, auxiliary plate frame 20, pressure cover spring 21, reversing seat 22, directional column 23, flat plate group 24, L-shaped push-pull plate 25, top frame 26, spring door 27, cylinder barrel 28, piston column 29, L-shaped flat plate 30, U-shaped spring 31. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the technical solutions in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] See also Figures 1 to 13 The present invention provides a technical solution: a square aluminum shell semi-solid battery pack, comprising a battery box frame 1, a battery pack core 2 with a square appearance is arranged in the battery box frame 1, and an isolated aluminum plate assembly 3 is arranged at the four vertical side positions between the battery box frame 1 and the battery pack core 2. The aluminum plate assembly 3 includes a square plate frame-shaped hard plate frame 4, a square aluminum plate 5 distributed in the middle of the hard plate frame 4, a row of limit units 6 that are in contact with each edge of the square aluminum plate 5, and a column frame 7 that is in contact with all the limit units 6 for transmission, the column frame 7 is distributed in parallel at one side of the hard plate frame 4, and a plate hole for heat dissipation is opened on the battery box frame 1 shell on one side of the square aluminum plate 5 A square frame 8 is placed flat above the battery pack core 2, and multiple groups of conductive metal sheets are fixed in the middle of the square frame 8, and the conductive metal sheets realize current transmission by contacting the electrode sheet ends on the battery pack core 2. The four corners of the square frame 8 are connected with spring groups 9. The two hard board frames 4 at the corners of the battery pack core 2 are vertically fixed to form an L-shaped vertical plate, and the spring group 9 is arranged on the L-shaped vertical plate. A control device 10 is connected to the upper end of each column frame 7. The control device 10 pushes the frame on the square frame 8 upward to make the square frame 8 rise, and the square frame 8 rises to disconnect the electrode sheet ends and the wire metal sheets of the battery pack core 2 from the power supply.

[0033] The present invention protects the battery pack inner core 2 by the square aluminum plates 5 on all four sides around it. At the same time, the heat generated during the charging and discharging of the battery pack inner core 2 can be quickly conducted out through the square aluminum plates 5, so that the battery pack inner core 2 is quickly dissipated. If the battery pack inner core 2 fails to work and generates too much heat during work, the heat transfer causes the square aluminum plates 5 themselves to have too high a temperature, causing the square aluminum plates 5 to expand and deform due to heat. In addition, accidental impact from the outside of the battery pack will directly cause the square aluminum plates 5 to deform. The two types of deformation mentioned above will automatically trigger subsequent power outages, that is, the square aluminum plates 5 will be powered off if they overheat or are subjected to severe external impacts, thereby avoiding safety problems during the charging and discharging of the battery pack. Timely power off can avoid the expansion of accidental safety problems.

[0034] refer to Figure 7 It is understood that the limiting unit 6 supports one side edge of the square aluminum plate 5, and the other side edge of the square aluminum plate 5 is also integrally connected with a square frame thin plate, and the limiting unit 6 and the back plate 11 fixed on the hard plate frame 4 cooperate to clamp the square frame thin plate of the square aluminum plate 5.

[0035] refer to Figure 5 It is understood that the spring group 9 includes an intercepting body 12 fixed on the hard board frame 4, a corner rod 14 fixedly connected to the square frame 8, and a spring 13 sleeved on the corner rod 14, the corner rod 14 slides through the through hole opened on the intercepting body 12, and the spring 13 is supported between the square frame 8 and the intercepting body 12.

[0036] refer to Figure 8 It is understood that the limit unit 6 includes a rubber plate 15 padded between the hard plate frame 4 and the square aluminum plate 5, a unit straight plate 19 distributed on one side of the rubber plate 15, a limit plate seat 18 that constrains the unit straight plate 19, a booster spring 16 connected between the limit plate seat 18 and the unit straight plate 19, and a transmission group 17 that contacts and transmits with the unit straight plate 19. The column frame 7 slides through a through hole opened at one end of the limit plate seat 18 by vertically fixing a directional column 23.

[0037] The edge of the square frame thin plate on the square aluminum plate 5 is stuck into the groove opened at one end of the rubber plate 15, and the other end of the rubber plate 15 is inserted into the plate groove opened on the hard plate frame 4. The unit straight plate 19 is provided with a convex block to contact the outer edge of the square aluminum plate 5.

[0038] The limit plate seat 18 is fixed on the hard plate frame 4 , the unit straight plate 19 slides through the plate hole opened on the limit plate seat 18 , one end of the booster spring 16 is fixed on the unit straight plate 19 , and the other end is fixed on the limit plate seat 18 .

[0039] The transmission group 17 includes a sub-plate frame 20 with one end fixed on the limit plate seat 18, a reversing seat 22 padded between the unit straight plate 19 and the column frame 7, and a pressure cover spring 21 supporting the reversing seat 22. One end of the pressure cover spring 21 is fixed on the sub-plate frame 20. The reversing seat 22 includes a concave block and a slider fixed on one side of the concave block. A semi-cylinder is arranged on the unit straight plate 19 to be inserted into the concave block of the reversing seat 22. The slider of the reversing seat 22 passes through the square hole opened on the sub-plate frame 20 and contacts the column frame 7.

[0040] The control device 10 includes an L-shaped push-pull plate 25 fixed on the column frame 7, a flat plate group 24 connected to one end of the L-shaped push-pull plate 25, and a top frame 26 supporting the flat plate group 24. The end of the top frame 26 is fixed on the hard plate frame 4, and the flat plate group 24 and the frame frame 8 are in contact transmission.

[0041] The plate group 24 includes an L-shaped plate 30 in contact with the square frame 8, a U-shaped spring piece 31 fixedly connected between the L-shaped plate 30 and the L-shaped push-pull plate 25, a piston column 29 arranged on the L-shaped plate 30, a cylinder barrel 28 with one end slidingly sleeved on the piston column 29, and a spring door 27 blocking the other end port of the cylinder barrel 28. The top frame 26 is provided with two symmetrical recessed blocks to clamp the L-shaped plate 30.

[0042] One end of the L-shaped plate 30 is provided with an inclined surface to push the frame of the square frame 8, and a triangular plate is provided on the L-shaped plate 30 to support and fix the piston column 29. The shrapnel door 27 includes a disk body and a C-shaped shrapnel fixed on one side of the disk body, and one end of the C-shaped shrapnel is fixed on the top frame 26, and a gas replenishing hole is opened in the middle of the disk body of the shrapnel door 27.

[0043] During the thermal expansion deformation of the square aluminum plate 5, the edge of the square aluminum plate 5 diffuses and deforms outwards. Fig.10 The edge of the square aluminum plate 5 in the middle is pushed to the right, causing the unit straight plate 19 to translate to the right. The external impact acts on the square aluminum plate 5, and the middle of the square aluminum plate 5 is concave, causing the edge of the square aluminum plate 5 to move relatively closer to the middle, that is, Fig.10 The edge of the square aluminum plate 5 is pushed to the left, and the unit straight plate 19 is translated to the left under the push of the boost spring sheet 16. The rubber plate 15 is a hard rubber material in the prior art. Although it constrains and limits the square aluminum plate 5, it does not affect the deformation of the square aluminum plate 5. The translation of the unit straight plate 19 in two directions will cause the semi-cylinder to push the concave block of the reversing seat 22, so that the reversing seat 22 overcomes the elastic force of the pressure cover spring sheet 21 and moves. The slider on the reversing seat 22 moves to lift the column frame 7. There are multiple reversing seats 22 in contact with the column frame 7. Any translation of the reversing seat 22 will cause the column frame 7 to move, that is, the column frame 7 moves away from the hard plate frame 4. Fig.11 The column frame 7 moves away from the hard plate frame 4 and drives the L-shaped push-pull plate 25. Fig.13The L-shaped push-pull plate 25 translates to the right, and then the L-shaped flat plate 30 is pulled by the U-shaped spring piece 31. The inclined surface of the L-shaped flat plate 30 translates to the right and pushes up the frame of the square frame 8, causing the square frame 8 to rise, so that the electrode sheet ends of the battery pack core 2 and the wire metal sheet are disconnected and separated.

[0044] The flat plate group 24 also has a delay mechanism. If only a short impact causes the vibration displacement of the square aluminum plate 5, rather than the complete deformation of the square aluminum plate 5 itself, the delay mechanism will work and will not cause subsequent power outages. The principle is that the shaking of the square aluminum plate 5 caused by the vibration is short-lived. After the shaking, the square aluminum plate 5 is quickly reset by the contact and pressure of the unit straight plate 19. The unit straight plate 19 quickly resets after moving the reversing seat 22. The reversing seat 22 lifts up the column frame 7 and then resets. The distance between the column frame 7 and the hard plate frame 4 increases briefly and then quickly shrinks and recovers. That is, Fig.13 The L-shaped push-pull plate 25 briefly translates to the right and then translates to the left to reset. Although the L-shaped push-pull plate 25 pulls the U-shaped spring sheet 31, it does not cause the L-shaped flat plate 30 to translate quickly. The speed of the L-shaped flat plate 30 to translate to the right is limited because the piston column 29 fixed on the L-shaped flat plate 30 is affected by the negative pressure environment in the cylinder barrel 28 during the axial movement to the right. It takes time for the external air to pass through the fine holes in the middle of the spring sheet door 27. The negative pressure environment affects the translation speed of the L-shaped flat plate 30. The L-shaped flat plate 30 does not effectively respond to the right translation. The L-shaped push-pull plate 25 has been reset, so the L-shaped flat plate 30 is close to motionless for a short time, and there is no subsequent rise of the square frame 8. The delay mechanism can avoid the problem of power failure due to vibration of the battery pack. Only when the external impact force is sufficient to cause the impact deformation of the square aluminum plate 5, or the overheating of the battery pack core 2 causes the thermal expansion deformation of the square aluminum plate 5, will the final safe power failure occur.

[0045] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A square aluminum shell semi-solid battery pack, comprising a battery box frame (1), characterized in that: The battery box frame (1) is provided with a battery pack core (2) having a square appearance. Four vertical side positions between the battery box frame (1) and the battery pack core (2) are provided with isolated aluminum plate assemblies (3). The aluminum plate assembly (3) comprises a square plate frame-shaped hard plate frame (4), a square aluminum plate (5) distributed in the middle of the hard plate frame (4), a row of limit units (6) on each edge of the square aluminum plate (5) in contact with each other, and a column frame (7) in contact with all the limit units (6). The column frame (7) is distributed in parallel at one side of the hard plate frame (4). A plate hole for heat dissipation is provided on the shell of the battery box frame (1) on one side of the square aluminum plate (5). The battery pack core (2) is placed flat on the top. A square frame (8) is provided, wherein a plurality of groups of conductive metal sheets are fixed in the middle of the square frame (8), and the conductive metal sheets achieve current transmission by contacting with the ends of the electrode sheets on the inner core (2) of the battery pack, and the four corners of the square frame (8) are connected to spring groups (9), and two hard plate square frames (4) at the corners of the inner core (2) of the battery pack are vertically fixed to form an L-shaped vertical plate, and the spring groups (9) are arranged on the L-shaped vertical plate, and the upper end of each column square frame (7) is connected to a control device (10), and the control device (10) causes the square frame (8) to rise by pushing the frame on the square frame (8) upward, and the square frame (8) causes the ends of the electrode sheets of the inner core (2) of the battery pack to be disconnected and separated from the conductive metal sheets by rising.

2. A square aluminum shell semi-solid battery pack according to claim 1, characterized in that: The limiting unit (6) supports one side edge of the square aluminum plate (5), and the other side edge of the square aluminum plate (5) is also integrally connected with a square frame thin plate, and the limiting unit (6) and the back plate (11) fixed on the hard plate square frame (4) cooperate to clamp the square frame thin plate of the square aluminum plate (5).

3. The square aluminum shell semi-solid battery pack according to claim 1, characterized in that: The spring group (9) comprises an interception body (12) fixed on the hard plate frame (4), a corner rod (14) fixedly connected to the frame frame (8), and a spring (13) sleeved on the corner rod (14), the corner rod (14) slidingly passing through a through hole formed on the interception body (12), and the spring (13) being supported between the frame frame (8) and the interception body (12).

4. The square aluminum shell semi-solid battery pack according to claim 2, characterized in that: The limiting unit (6) comprises a rubber plate (15) padded between the hard plate frame (4) and the square aluminum plate (5), a unit straight plate (19) distributed on one side of the rubber plate (15), a limiting plate seat (18) for restraining the unit straight plate (19), a booster spring (16) connected between the limiting plate seat (18) and the unit straight plate (19), and a transmission group (17) for contact transmission with the unit straight plate (19), and a through hole opened at one end of the limiting plate seat (18) is slidably passed through the column frame (7) by means of a vertically fixed directional column (23).

5. A square aluminum shell semi-solid battery pack according to claim 4, characterized in that: The edge of the square frame thin plate on the square aluminum plate (5) is inserted into a groove formed at one end of the rubber plate (15), and the other end of the rubber plate (15) is inserted into a plate groove formed on the hard plate square frame (4). The unit straight plate (19) is provided with a protrusion to contact the outer edge of the square aluminum plate (5).

6. The square aluminum shell semi-solid battery pack according to claim 4, characterized in that: The limit plate seat (18) is fixed on the hard plate frame (4), the unit straight plate (19) slides through the plate hole opened on the limit plate seat (18), and one end of the booster spring (16) is fixed on the unit straight plate (19) and the other end is fixed on the limit plate seat (18).

7. The square aluminum shell semi-solid battery pack according to claim 4, characterized in that: The transmission group (17) includes a sub-plate frame (20) having one end fixed on the limit plate seat (18), a reversing seat (22) padded between the unit straight plate (19) and the column frame (7), and a pressure cover spring sheet (21) supporting the reversing seat (22), one end of the pressure cover spring sheet (21) is fixed on the sub-plate frame (20), the reversing seat (22) includes a concave block and a slider fixed on one side of the concave block, a semi-cylinder is arranged on the unit straight plate (19) to be inserted into the concave block of the reversing seat (22), and the slider of the reversing seat (22) passes through the square hole opened on the sub-plate frame (20) and contacts with the column frame (7).

8. The square aluminum shell semi-solid battery pack according to claim 1, characterized in that: The control device (10) comprises an L-shaped push-pull plate (25) fixed on the column frame (7), a flat plate group (24) connected to one end of the L-shaped push-pull plate (25), and a top frame (26) supporting the flat plate group (24), the end of the top frame (26) being fixed on the hard plate frame (4), and the flat plate group (24) and the frame frame (8) are in contact transmission.

9. The square aluminum shell semi-solid battery pack according to claim 8, characterized in that: The plate group (24) comprises an L-shaped plate (30) in contact with the square frame (8), a U-shaped spring piece (31) fixedly connected between the L-shaped plate (30) and the L-shaped push-pull plate (25), a piston column (29) arranged on the L-shaped plate (30), a cylinder barrel (28) with one end slidingly sleeved on the piston column (29), and a spring piece door (27) blocking the other end port of the cylinder barrel (28), and the top frame (26) is provided with two symmetrical concave blocks to clamp the L-shaped plate (30).

10. The square aluminum shell semi-solid battery pack according to claim 9, characterized in that: One end of the L-shaped plate (30) is provided with an inclined surface to push the frame of the square frame (8), and a triangular plate is provided on the L-shaped plate (30) to support and fix the piston column (29). The spring door (27) comprises a disk body and a C-shaped spring fixed to one side of the disk body, and one end of the C-shaped spring is fixed to the top frame (26). A fine air replenishing hole is provided in the middle of the disk body of the spring door (27).

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