Pressure maintaining device

Abstract

The utility model relates to a pressure maintaining device which comprises a tray used for bearing a battery; the two groups of pressing plate assemblies are oppositely arranged at intervals and are movably arranged on the tray; the self-locking lead screw is rotationally connected with the two sets of pressing plate assemblies correspondingly, and the self-locking lead screw can rotate in two directions to drive the two sets of pressing plate assemblies to be close to each other or away from each other; and the driving unit is used for driving the self-locking screw rod to rotate in two directions. The pressure maintaining device has the advantages of being simple in structure and convenient to maintain.

Description

Technical Field

[0001] The present application relates to the technical field of battery production, and in particular to a pressure maintaining device. Background Art

[0002] With the development of new energy, more and more fields are using new energy as power. Due to its advantages of high energy density, rechargeable, safe and environmentally friendly, power batteries are widely used in new energy vehicles, consumer electronics, energy storage systems and other fields.

[0003] However, in the actual production process of batteries, it is often necessary to use a device to press the two ends of the battery to apply sufficient pressure to facilitate subsequent production processes. However, current pressure-maintaining devices often require equipment to provide pressure, so the structure is complex. Utility Model Content

[0004] Based on this, it is necessary to provide a pressure maintaining device to address the problem of complex structure.

[0005] The first aspect of the present application provides a pressure-maintaining device, comprising: a tray for carrying batteries; two groups of pressure plate assemblies arranged at relative intervals and movably arranged on the tray; a self-locking screw rod, rotatably connected to the two groups of pressure plate assemblies, respectively, and the self-locking screw rod can rotate in both directions to drive the two groups of pressure plate assemblies to move closer to or away from each other; and a driving unit for driving the self-locking screw rod to rotate in both directions.

[0006] In one of the embodiments, the pressure maintaining device includes at least one slide rail, the slide rail is fixed on the tray, and the two pressure plate assemblies are respectively slidably disposed on the slide rail.

[0007] In one of the embodiments, the pressure maintaining device includes two groups of slide rails arranged at intervals; each group of the pressure plate assembly includes a connecting rod, a fixed seat, a pressure plate, a rotating frame and two sliders, the two sliders are fixed at both ends of the connecting rod, and the pressure plate is fixed to the connecting rod through the fixed seat; the rotating frame is fixed to the connecting rod; the connecting rod is horizontally mounted above the two slide rails, and is slidably connected to the two slide rails through the two sliders; a threaded hole that cooperates with the self-locking screw is formed on the rotating frame.

[0008] In one embodiment, the pressing plate assembly includes an elastic member, and the elastic member is disposed between the pressing plate and the fixing seat.

[0009] In one embodiment, the self-locking screw is a trapezoidal thread self-locking screw.

[0010] In one embodiment, the self-locking screw has a first thread segment and a second thread segment, the first thread segment is rotatably connected to one group of the pressure plate assemblies; the second thread segment is rotatably connected to another group of the pressure plate assemblies; the threads of the first thread segment and the second thread segment are set in opposite directions.

[0011] In one of the embodiments, a connecting portion is formed on at least one end of the self-locking screw rod; the connecting portion can be circumferentially limited with the driving unit.

[0012] In one embodiment, the drive unit has a first position relatively close to the tray and a second position relatively far away from the tray; when the drive unit is in the first position, the connection portion between the drive unit and the self-locking screw is circumferentially limited; when the drive unit is in the second position, the connection portion between the drive unit and the self-locking screw is separated.

[0013] In one embodiment, the driving unit includes a cylinder, a driver and a connector, and the connector is transmission-connected to the output end of the driver; the cylinder can drive the driver to reciprocate so that the driving unit switches between the first position and the second position; when the driving unit is in the first position, the connecting part between the connector and the self-locking screw is circumferentially limited, and the driver can drive the self-locking screw to rotate forward or reversely through the connector; when the driving unit is in the second position, the connecting part between the connector and the self-locking screw is separated.

[0014] In one embodiment, the connecting portion is a straight slot or a cross slot; the connector includes a cross bar that cooperates with the connecting portion for positioning.

[0015] The beneficial effects are:

[0016] A pressure-maintaining device according to an embodiment of the present application is provided with a tray, two groups of pressure plate assemblies, a self-locking screw and a driving unit; the tray is used to carry batteries; the two groups of pressure plate assemblies are movably arranged on the tray and are arranged relatively spaced along a first direction X; the two ends of the self-locking screw are respectively rotatably connected to the two groups of pressure plate assemblies, and the self-locking screw can rotate in both directions to drive the two groups of pressure plate assemblies to move closer to each other or away from each other; the driving unit is used to drive the self-locking screw to rotate in both directions; when the battery is carried on the tray, the self-locking screw is driven by the driving unit to rotate forward, thereby ensuring that the self-locking screw can drive the two groups of pressure plate assemblies to move closer to each other along the first direction X, and then ensuring that the two groups of pressure plate assemblies can be respectively crimped on the top and bottom ends of the battery along the first direction, and when the driving unit stops moving, the self-locking screw can rely on its own locking characteristics to ensure that the two groups of pressure plate assemblies still maintain pressure on both ends of the battery; there is no need to maintain pressure through a complex driving structure, so that the pressure-maintaining device has a simple structure and is easy to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a pressure-maintaining device and a battery provided in some embodiments of the present application; in the figure, the driving unit is in the first position.

[0018] Figure 2 A schematic diagram of the structure of a drive unit provided in some embodiments of the present application.

[0019] Figure 3 A schematic diagram of the structure of a pressure-maintaining device provided in some embodiments of the present application, wherein the driving unit is omitted.

[0020] Figure 4 A schematic diagram of the structure of a pressure-maintaining device and a battery provided in some embodiments of the present application; in the figure, one drive unit is in a first position and the other drive unit is in a second position. DETAILED DESCRIPTION

[0021] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] In the description of the embodiments of the present application, if the technical terms "first", "second", etc. appear, these terms are only used for descriptive purposes to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present application, if the term "multiple" appears, "multiple" means at least two (including two), such as two, three, etc., unless otherwise clearly and specifically defined. Similarly, if the term "multiple groups" appears, "multiple groups" refers to more than two groups (including two groups), and if the term "multiple sheets" appears, "multiple sheets" refers to more than two sheets (including two sheets).

[0027] In the description of the embodiments of the present application, if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the embodiments of the present application and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0028] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, if the technical terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0029] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0030] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0031] See also Figures 1 to 4 As shown, the first aspect of the embodiment of the present application provides a pressure-maintaining device. The pressure-maintaining device includes: a tray 10, two sets of pressure plate assemblies 20, a self-locking screw 30 and a driving unit 40

[0032] Among them, the tray 10 is used to carry the battery 90; the two groups of pressure plate assemblies 20 are movably arranged on the tray 10 and are relatively spaced along the first direction X; the two ends of the self-locking screw 30 are respectively rotatably connected to the two groups of pressure plate assemblies 20, and the self-locking screw 30 can rotate in both directions to drive the two groups of pressure plate assemblies 20 to move closer to each other or away from each other; the driving unit 40 is used to drive the self-locking screw 30 to rotate in both directions.

[0033] In the embodiment of the present application, the bidirectional rotation of the self-locking screw 30 refers to the positive rotation of the self-locking screw 30 in the clockwise direction around its own axis and the reverse rotation in the counterclockwise direction. For the convenience of description, when the self-locking screw 30 rotates in the forward direction, it can drive the two groups of pressure plate assemblies 20 to move closer to each other along the first direction X; when the self-locking screw 30 rotates in the reverse direction, it can drive the two groups of pressure plate assemblies 20 to move away from each other along the first direction X.

[0034] When the battery 90 is carried on the tray 10, the self-locking screw 30 is driven to rotate in the forward direction by the driving unit 40, thereby ensuring that the self-locking screw 30 can drive the two groups of pressure plate assemblies 20 to move closer to each other along the first direction X, thereby ensuring that the two groups of pressure plate assemblies 20 can be respectively crimped on the top and bottom ends of the battery 90 along the first direction. When the driving unit 40 stops moving, the self-locking screw 30 can rely on its own locking characteristics to ensure that the two groups of pressure plate assemblies 20 still maintain pressure on both ends of the battery 90; there is no need to maintain pressure through a complex driving structure, so that the pressure maintaining device has a simple structure and is easy to maintain.

[0035] When the battery 90 is pressurized and needs to be removed from the tray 10, the self-locking screw 30 is driven to rotate in the opposite direction by the driving unit 40, thereby ensuring that the self-locking screw 30 can drive the two groups of pressure plate assemblies 20 to move away from each other along the first direction X, thereby making the two groups of pressure plate assemblies 20 disengage from both ends of the battery 90, thereby facilitating subsequent production and testing processes.

[0036] In some possible embodiments, see Figures 1 to 4As shown, the pressure-maintaining device includes at least one slide rail 50. The slide rail 50 can extend along the first direction X and be fixed on the tray 10, and the two pressure plate assemblies 20 are respectively slidably disposed on the slide rail 50. In this way, the pressure plate assemblies 20 can be guided by the slide rail 50 to move closer to each other or away from each other along the first direction X, thereby realizing the pressure-maintaining function of the pressure-maintaining device on the battery 90.

[0037] In some possible embodiments, see Figures 1 to 4 As shown, the pressure maintaining device includes two groups of slide rails 50 arranged at intervals; each group of pressure plate assemblies 20 includes a connecting rod 21, a fixed seat 22, a pressure plate 23, a rotating frame 25 and two sliders 24, the two sliders 24 are fixed at both ends of the connecting rod 21, and the pressure plate 23 is fixed to the connecting rod 21 through the fixed seat 22; the rotating frame 25 is fixed to the connecting rod 21; the connecting rod 21 is horizontally mounted above the two slide rails 50, and is slidably connected to the two slide rails 50 through the two sliders 24; a threaded hole 26 that cooperates with the self-locking screw 30 is formed on the rotating frame 25.

[0038] The two sets of slide rails 50 can be arranged on the tray 10 at intervals along the second direction Y. In each embodiment of the present application, the second direction Y and the first direction X are directions in the plane where the tray 10 is located, and the second direction Y and the first direction X are intersecting, and usually the second direction Y is perpendicular to the first direction X.

[0039] By setting each group of pressure plate assemblies 20 to include a connecting rod 21, a fixed seat 22, a pressure plate 23, a rotating frame 25 and two sliders 24, when the driving unit 40 drives the self-locking screw 30 to rotate forward or reverse, the threaded cooperation between the self-locking screw 30 and the threaded hole 26 converts its own rotation into axial movement of the rotating frame 25 relative to the self-locking screw 30, and the rotating frame 25 drives the connecting rod 21 to move forward or backward along the first direction X relative to the slide rail 50, and finally enables the pressure plate 23 fixed on the connecting rod 21 to move forward or backward along the first direction X, thereby maintaining the pressure of the battery 90 or separating from the battery 90, and finally realizing the pressure maintaining function of the pressure maintaining device on the battery 90.

[0040] Optionally, the pressing plate 23 may be an insulating rubber plate to prevent electrical conduction with the battery 90 .

[0041] In some possible embodiments, see Figures 1 to 4 As shown, the pressing plate assembly 20 includes an elastic member 27 , and the elastic member 27 is disposed between the pressing plate 23 and the fixing seat 22 .

[0042] By arranging the elastic member 27 between the pressing plate 23 and the fixing seat 22 , the force exerted by the two sets of pressing plate assemblies 20 on the battery 90 can be effectively controlled to prevent the pressing plate 23 from crushing the two ends of the battery 90 .

[0043] Optionally, the elastic member 27 may be a spring, a rubber pad or other buffer structures.

[0044] In some possible embodiments, the self-locking screw 30 is a trapezoidal thread self-locking screw. The trapezoidal thread has a self-locking property, that is, when a load is applied to the self-locking screw 30, due to its large friction resistance, the self-locking screw 30 can be prevented from rotating and loosening by itself; in this way, the self-locking property of the self-locking screw 30 is utilized to ensure that the two sets of pressure plate assemblies 20 still maintain pressure on both ends of the battery 90; there is no need to maintain pressure through a complex driving structure, so that the pressure-maintaining device has a simple structure and is easy to maintain.

[0045] In some possible embodiments, see Figures 1 to 4 As shown, the self-locking screw 30 has a first thread segment 31 and a second thread segment 32. The first thread segment 31 is rotatably connected to one group of pressure plate assemblies 20, and the second thread segment 32 is rotatably connected to the other group of pressure plate assemblies 20. The threads of the first thread segment 31 and the second thread segment 32 are set in opposite directions.

[0046] By setting the threads of the first thread segment 31 and the second thread segment 32 in opposite directions, the thread directions of the threaded holes 26 on the rotating frames 25 of the two pressure plate assemblies 20 are also correspondingly set in opposite directions.

[0047] Combination Figure 3 In the position shown, when the self-locking screw 30 rotates in the positive direction, the rotating frame 25 of the pressing plate assembly 20 on the lower left side cooperates with the first thread segment 31 through the threaded hole 26, and moves to the upper right side along the first direction X; the rotating frame 25 of the pressing plate assembly 20 on the upper right side cooperates with the second thread segment 32 through the threaded hole 26, and moves to the lower left side along the first direction X; in this way, the two groups of pressing plate assemblies 20 are brought closer to each other along the first direction X;

[0048] Combination Figure 3 In the position shown, when the self-locking screw 30 rotates in the reverse direction, the two groups of pressure plate assemblies 20 move away from each other along the first direction X. The principle is similar to that in the previous section and will not be repeated here.

[0049] Optionally, the rotating frame 25 and the first thread segment 31 on one set of the pressure plate assemblies 20 both adopt right-handed threads and are threadedly connected; the rotating frame 25 and the second thread segment 32 on the other set of the pressure plate assemblies 20 both adopt left-handed threads.

[0050] In some possible embodiments, see Figures 1 to 4 As shown, a connecting portion 33 is formed at at least one end of the self-locking screw rod 30 ; the connecting portion 33 can be circumferentially limited with the driving unit 40 .

[0051] In this way, the connection part and the driving unit 40 are only limited in the circumferential direction, and are movable in the axial direction, so as to facilitate the connection between the driving unit 40 and the connection part 33, and further drive the self-locking screw 30 to rotate in both directions.

[0052] Optionally, see Figures 1 to 4 As shown, the pressure-maintaining device may be provided with only one set of driving units 40, which are provided at one end of the self-locking screw 30. The pressure-maintaining device may also be provided with two sets of driving units 40, which are respectively provided at both ends of the self-locking screw 30, so that one set of driving units 40 or two sets of driving units 40 can be flexibly selected according to needs to drive the self-locking screw 30 to rotate.

[0053] In some possible embodiments, see Figures 1 to 4 As shown, the drive unit 40 has a first position relatively close to the tray 10 and a second position relatively far away from the tray 10; when the drive unit 40 is in the first position, the drive unit 40 and the connecting portion 33 of the self-locking screw 30 are circumferentially limited; when the drive unit 40 is in the second position, the drive unit 40 and the connecting portion 33 of the self-locking screw 30 are separated.

[0054] The driving unit 40 can move relative to the tray 10. The driving unit 40 is in the first position. The connection portion 33 between the driving unit 40 and the self-locking screw 30 is circumferentially limited. The driving unit 40 drives the self-locking screw 30 to rotate forward or reversely, thereby ensuring that the self-locking screw 30 can drive the two groups of pressure plate assemblies 20 to move closer to or away from each other along the first direction X. The driving unit 40 is in the second position. The connection portion 33 between the driving unit 40 and the self-locking screw 30 is separated; the self-locking screw 30 can rely on its own locking characteristics to ensure that the two groups of pressure plate assemblies 20 still maintain pressure on both ends of the battery 90; there is no need to maintain pressure through a complex driving structure, so that the pressure-maintaining device has a simple structure and is easy to maintain.

[0055] In some possible embodiments, see Figures 1 to 4 As shown, the driving unit 40 includes a cylinder 41, a fixing plate 42, a driver 43 and a connector 44. The driver 43 is connected to the cylinder 41 through the fixing plate 42, and the connector 44 is transmission-connected to the output end of the driver 43. The cylinder 41 can drive the driver 43 to move back and forth so that the driving unit 40 switches between the first position and the second position.

[0056] When the driving unit 40 is in the first position, the connector 44 and the connecting portion 33 of the self-locking screw 30 are circumferentially limited, and the driver 43 can drive the self-locking screw 30 to rotate forward or reversely through the connector 44; when the driving unit 40 is in the second position, the driver 43 is relatively far away from the tray 10; the connector 44 is separated from the connecting portion 33 of the self-locking screw 30.

[0057] The driver 43 may be a servo motor.

[0058] The cylinder 41 pushes the driver 43 as a whole to approach the tray 10, so that the drive unit 40 is in the first position, and the connector 44 on the driver 43 is circumferentially limited with the connecting portion 33 of the self-locking screw 30; in this way, the driver 43 can drive the self-locking screw 30 to rotate forward or reverse, thereby ensuring that the self-locking screw 30 can drive the two groups of pressure plate assemblies 20 to move closer to or away from each other along the first direction X.

[0059] The cylinder 41 pushes the driver 43 as a whole away from the tray 10, so that the drive unit 40 is in the second position, and the drive unit 40 is separated from the connecting part 33 of the self-locking screw 30; the self-locking screw 30 can rely on its own locking characteristics to ensure that the two sets of pressure plate assemblies 20 still maintain pressure on both ends of the battery 90; there is no need to maintain pressure through a complex driving structure, so that the pressure maintaining device has a simple structure and is easy to maintain.

[0060] In some possible embodiments, see Figures 1 to 4 As shown, the driving unit 40 includes a transmission belt 47; the connector 44 is connected to the output end of the driver 43 through the transmission belt 47, and the structure is simple and the transmission is stable and reliable.

[0061] In some possible embodiments, see Figures 1 to 4 As shown, the connecting portion 33 is a slot or a cross slot; the connector 44 includes a cross bar 46 that cooperates with the slot or the cross slot for positioning. The cross bar 46 is a slender rod and can be transversely embedded in the slot of the connecting portion 33 to achieve circumferential limitation.

[0062] In some possible embodiments, the connector 44 includes a U-shaped connecting frame 45 , one end of which is transmission-connected to the output end of the driver 43 via a transmission belt 47 ; and a crossbar 46 is supported between two side walls of the connecting frame 45 .

[0063] The axis of the cross bar 46 intersects with the axis of the self-locking screw 30 .

[0064] In this way, the output end of the driver 43 drives the connector 44 to rotate through the transmission belt 47, and then drives the cross bar 46 to rotate around the axial direction of the self-locking screw 30, and drives the self-locking screw 30 to rotate forward or reverse through the S-shaped groove or the cross groove; and then the two groups of pressure plate assemblies 20 can be driven to move closer to each other or away from each other, and finally the pressure maintaining function of the pressure maintaining device on the battery 90 can be realized.

[0065] In some possible embodiments, see Figures 1 to 4As shown, the driving unit 40 includes an origin sensor 48, which is arranged on the fixed plate 42 and is used to sense the rotation angle of the output end of the driver 43, so as to accurately drive the two groups of pressure plate assemblies 20 to move closer to or away from each other, and finally realize the pressure maintaining function of the pressure maintaining device on the battery 90.

[0066] Optionally, the tray 10 may adopt an insulating rubber sheet to prevent electrical conduction with the battery 90 .

[0067] Optionally, the tray 10 may be a metal plate, and an insulating layer may be coated on the surface of the metal plate to prevent electrical conduction with the battery 90 .

[0068] In some possible embodiments, see Figures 1 to 4 As shown, the pressure maintaining device includes two pads 60 arranged on the tray 10; the two pads 60 are arranged relatively spaced apart along the second direction Y to form a gap 61; the pads 60 are made of insulating rubber plates to prevent electrical conduction with the battery 90.

[0069] In some possible embodiments, see Figures 1 to 4 As shown, the middle section of the self-locking screw rod 30 is inserted into the gap 61; thus, the space can be simplified and the structure can be compact.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A pressure-maintaining device, characterized in that: The pressure maintaining device comprises: A tray (10) for carrying a battery (90); Two sets of pressure plate assemblies (20) are arranged relatively spaced apart and movably disposed on the tray (10); A self-locking screw (30) is rotatably connected to the two groups of the pressure plate assemblies (20), respectively, and the self-locking screw (30) can rotate in both directions to drive the two groups of pressure plate assemblies (20) to move closer to each other or away from each other; And a driving unit (40) for driving the self-locking screw rod (30) to rotate bidirectionally.

2. The pressure maintaining device according to claim 1, characterized in that: The pressure-maintaining device comprises at least one slide rail (50), the slide rail (50) being fixed on the tray (10), and the two pressure plate assemblies (20) being slidably disposed on the slide rail (50) respectively.

3. The pressure maintaining device according to claim 2, characterized in that: The pressure-maintaining device comprises two sets of slide rails (50) arranged at intervals; Each group of the pressure plate assembly (20) comprises a connecting rod (21), a fixing seat (22), a pressure plate (23), a rotating frame (25) and two sliders (24); the two sliders (24) are fixed to two ends of the connecting rod (21); the pressure plate (23) is fixed to the connecting rod (21) via the fixing seat (22); the rotating frame (25) is fixed to the connecting rod (21); The connecting rod (21) is horizontally mounted above the two slide rails (50) and is slidably connected to the two slide rails (50) via the two sliding blocks (24); The rotating frame (25) is formed with a threaded hole (26) that cooperates with the self-locking screw rod (30).

4. The pressure maintaining device according to claim 3, characterized in that: The pressing plate assembly (20) comprises an elastic member (27), wherein the elastic member (27) is arranged between the pressing plate (23) and the fixing seat (22).

5. The pressure maintaining device according to any one of claims 1 to 4, characterized in that: The self-locking screw (30) is a trapezoidal thread self-locking screw.

6. The pressure maintaining device according to any one of claims 1 to 4, characterized in that: The self-locking screw rod (30) has a first threaded section (31) and a second threaded section (32); the first threaded section (31) is rotatably connected to one group of the pressure plate assemblies (20); and the second threaded section (32) is rotatably connected to another group of the pressure plate assemblies (20); The threads of the first thread segment (31) and the second thread segment (32) are arranged in opposite directions.

7. The pressure maintaining device according to any one of claims 1 to 4, characterized in that: At least one end of the self-locking screw rod (30) is formed with a connecting portion (33); the connecting portion (33) can be circumferentially limited with the driving unit (40).

8. The pressure maintaining device according to claim 7, characterized in that: The driving unit (40) has a first position relatively close to the tray (10) and a second position relatively far from the tray (10); When the drive unit (40) is in the first position, the connection portion (33) between the drive unit (40) and the self-locking screw rod (30) is circumferentially limited; When the driving unit (40) is in the second position, the driving unit (40) is separated from the connecting portion (33) of the self-locking screw rod (30).

9. The pressure maintaining device according to claim 8, characterized in that: The driving unit (40) comprises a cylinder (41), a driver (43) and a connector (44), wherein the connector (44) is drivingly connected to an output end of the driver (43); The cylinder (41) is capable of driving the driver (43) to reciprocate so that the drive unit (40) switches between the first position and the second position; When the drive unit (40) is in the first position, the connector (44) and the connecting portion (33) of the self-locking screw (30) are circumferentially limited, and the driver (43) can drive the self-locking screw (30) to rotate forward or reverse through the connector (44); When the drive unit (40) is in the second position, the connector (44) is separated from the connecting portion (33) of the self-locking screw rod (30).

10. The pressure maintaining device according to claim 9, characterized in that: The connecting portion (33) is a straight slot or a cross slot; the connector (44) comprises a cross bar (46) that cooperates with the connecting portion (33) for positioning.

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