CN216850056U - Lead-acid storage battery - Google Patents

Abstract

The utility model relates to a lead acid battery belongs to battery technical field, has solved the problem that lead acid battery preparation process is complicated among the prior art, the structure is unstable. The battery comprises a battery jar, an upper cover, a lower cover and a polar plate arranged in the battery jar, wherein the upper frame and the lower frame of the polar plate are respectively provided with at least one polar lug; a plurality of single lattices which are communicated with the upper end and the lower end inside the battery jar are arranged inside the battery jar, the upper end of the battery jar is open, the lower end of the battery jar comprises a bottom plate, and the bottom plate is provided with a plurality of openings corresponding to the lugs; the pole ear of the lower frame of the pole plate passes through the opening at the lower end of the battery jar, the lower frame of the pole plate is contacted with the bottom plate, the homopolar pole ear at the upper end of the battery jar is connected through the upper bus bar, and the homopolar pole ear at the lower end of the battery jar is connected through the lower bus bar. The utility model discloses a convenient assembly of lead acid battery, stable in structure.

Description

Lead-acid storage battery

Technical Field

The utility model relates to the technical field of batteries, especially, relate to a lead acid battery.

Background

In the prior art, only the upper part of a lead-acid storage battery is provided with a bus bar, and current is collected and diffused from a lug. The discharge depth near the tab is high, the current density is high, the utilization rate of active substances is high, the volume change of the positive active substances is large in the recycling process, the gas is firstly over-inflated and deflated near the tab during charging, and the positive active substances at the tab are loosened and fall off at the earliest time under the double influence. The falling gradually diffuses in the opposite direction of the electrode lug, the active substance gradually loses efficacy, and the service life of the battery is further shortened.

The polar plate is provided with a plurality of polar lugs, so that the defects can be effectively overcome. To the battery that the polar plate all set up utmost point ear about, the lower extreme all is uncovered on the battery jar, has the battery of busbar to last lower part, is difficult to control the polar plate position during the assembly, and the assembly process is complicated, and the unstable structure, causes the damage to the polar plate easily.

SUMMERY OF THE UTILITY MODEL

In view of the above analysis, the present invention aims to provide a lead-acid battery for solving the problems of complex manufacturing process and unstable structure of the existing lead-acid battery.

The purpose of the utility model is mainly realized through the following technical scheme:

the utility model provides a lead-acid storage battery, which comprises a battery jar, an upper cover, a lower cover and a polar plate arranged in the battery jar, wherein the upper frame and the lower frame of the polar plate are respectively provided with at least one polar ear; the battery jar is internally provided with a plurality of single lattices which are communicated with the upper end and the lower end of the battery jar, the upper end of the battery jar is open, the lower end of the battery jar comprises a bottom plate, and the bottom plate is provided with a plurality of openings corresponding to the lugs; the pole lugs of the lower frame of the pole plate penetrate through the opening at the lower end of the battery jar, the lower frame of the pole plate is contacted with the bottom plate, the homopolar pole lugs at the upper end of the battery jar are connected through the upper bus bar, and the homopolar pole lugs at the lower end of the battery jar are connected through the lower bus bar.

Preferably, the upper cover is matched with the upper end of the battery jar, and the inner surface of the upper cover is provided with an upper groove matched with an upper bus bar on the upper part of the battery jar and a pole post hole matched with the positive pole post and the negative pole post.

Preferably, the lower cover is matched with the lower end of the battery jar, and the inner surface of the lower cover is provided with a lower groove matched with the lower busbar at the lower part of the battery jar.

Preferably, the electrode plate comprises a positive electrode plate and a negative electrode plate, and the positive electrode plate and the negative electrode plate are separated by a separator.

Preferably, a plurality of the openings are continuously arranged along the arrangement direction of the unit cells, the length C of the openings along the arrangement direction of the unit cells is equal to the width H of the unit cells, and the width H of the openings is greater than the width n of the tabs.

Preferably, the same-polarity bus bars at the upper end and the lower end of the battery jar are connected through conducting wires, and a positive pole column and a negative pole column are respectively arranged at the external output of the positive pole bus bar at the upper end and the external output of the negative pole bus bar.

Preferably, the lead is located within the battery well.

Preferably, the outer wall of the battery jar is provided with an outer wall groove and a cover plate matched with the outer wall groove, the conducting wire is arranged in the outer wall groove, and after the cover plate is covered on the outer wall groove, the outer wall of the battery jar forms a complete plane matched with the upper cover and the lower cover.

Preferably, the upper frame and the lower frame of the pole plate are respectively provided with a tab, and the tabs of the upper frame and the tabs of the lower frame are respectively positioned on two sides of the central line of the pole plate.

Preferably, the upper frame and the lower frame of the pole plate are respectively provided with a plurality of pole lugs, and any two pole lugs on the same frame are asymmetric about the central line of the pole plate.

Compared with the prior art, the utility model discloses can realize one of following beneficial effect at least:

1. the utility model discloses a battery tank bottom and superstructure of battery are different completely, and upper portion is uncovered, sets up the trompil that a plurality of confessions utmost point ear and busbar stretch out on the bottom plate, and the lower extreme is distinguished easily, improves the efficiency of assembly battery.

2. The utility model discloses a battery tank bottom of battery sets up the bottom plate that contains partial trompil, support and fix a position the polar plate in the battery tank through the bottom plate, when assembling the battery, directly pack into the battery tank with utmost point crowd, utmost point ear on the lower frame of polar plate passes the trompil, the lower frame and the bottom plate contact of polar plate, support through the bottom plate and fix a position the lower frame of polar plate, make the polar plate can not slide from top to bottom, the battery is in the use, when using in vibration environment, can not lead to the position of utmost point crowd in the battery to beat because of having no bottom plate to support, utmost point ear fracture even. When the lower bus bar is installed, the lower bus bar can be directly installed on the lug without pushing the polar plate back and forth; and, separate lower busbar and polar plate through the bottom plate, avoid corroding the lower busbar because of the liquid outflow in the polar plate. The storage battery has a stable internal structure and is not easy to damage in the using process.

3. The utility model discloses a homopolar busbar of the upper end of battery and lower extreme passes through the wire and connects, and the positive pole busbar of upper end sets up a positive post and a negative pole post respectively to the external output department and the external output department of negative pole busbar, promptly, the utility model discloses only the terminal on upper portion avoids producing the danger that the battery lower part bumps with other conductive object and touches and produce the short circuit to, no terminal is made to the lower part battery simple structure, can also avoid the battery height that must increase because of setting up the terminal.

The utility model discloses in, can also make up each other between the above-mentioned each technical scheme to realize more preferred combination scheme. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout the drawings.

FIG. 1 is a schematic view of the upper portion of a lead acid battery (excluding the upper cover);

FIG. 2 is a schematic view of the structure of the lower part of a lead-acid battery (excluding a lower cover);

FIG. 3 is a schematic structural diagram of a lead-acid battery (including an upper cover and a lower cover);

FIG. 4 is a schematic diagram of a plate with 1 tab on each of the upper and lower sides;

FIG. 5 is a schematic view of a plurality of electrode groups formed by stacking a positive electrode plate and a negative electrode plate each having 1 tab at the upper and lower sides thereof;

FIG. 6 is a schematic diagram of a plate with 2 tabs respectively arranged at the upper side and the lower side;

fig. 7 is a schematic view showing the superposition of a positive plate and a negative plate each having 2 tabs at the upper and lower sides thereof.

FIG. 8 is a schematic view of the upper end of the battery well;

FIG. 9 is a schematic view of the lower end of the battery well;

FIG. 10 is a schematic view of the inner surface structure of the upper cover;

fig. 11 is a schematic view of the inner surface structure of the lower cover.

Reference numerals:

1-a battery jar; 101-unit cell; 102-opening a hole; 103-a backplane; 2-covering the upper cover; 201-upper groove; 202-pole hole; 3-lower cover; 301-lower groove; 302-reinforcing ribs; 4-pole plate; 5-pole ear; 501-positive tab; 502-negative tab; 6-a wire; 7-a busbar; 8-pole column; 9-terminal; c-length of the opening along the direction of arrangement of the cells; h-width of the opening; h-width of the cell; n-the width of the tab.

Detailed Description

The following detailed description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.

The utility model provides a lead-acid storage battery, as shown in figures 1-3, 8 and 9, the lead-acid storage battery comprises a battery jar 1, an upper cover 2, a lower cover 3 and a polar plate 4 arranged in the battery jar 1, wherein the upper frame and the lower frame of the polar plate 4 are respectively provided with at least one polar ear 5; a plurality of single lattices 101 for communicating the upper end and the lower end of the interior of the battery jar 1 are arranged in the battery jar 1, the upper end of the battery jar 1 is open, the lower end of the battery jar 1 comprises a bottom plate 103, and the bottom plate 103 is provided with a plurality of open holes 102 corresponding to the lugs 5; the pole lugs of the lower frame of the pole plate 4 penetrate through the opening 102 at the lower end of the battery jar 1, the lower frame of the pole plate 4 is contacted with the bottom plate 103, the homopolar pole lugs at the upper end of the battery jar 1 are connected through the upper bus bar, and the homopolar pole lugs at the lower end of the battery jar 1 are connected through the lower bus bar.

The utility model discloses a battery tank bottom and superstructure of battery are different completely, and upper portion is uncovered, sets up the trompil that a plurality of confessions utmost point ear and busbar stretch out on the bottom plate, and the lower extreme is distinguished easily, improves the efficiency of assembly battery.

The utility model discloses a battery tank bottom of battery sets up the bottom plate that contains partial trompil, support and fix a position the polar plate in the battery tank through the bottom plate, when assembling the battery, directly pack into the battery tank with utmost point crowd, utmost point ear on the lower frame of polar plate passes the trompil, the lower frame and the bottom plate contact of polar plate, support through the bottom plate and fix a position the lower frame of polar plate, make the polar plate can not slide from top to bottom, the battery is in the use, when using in vibration environment, can not lead to the position of utmost point crowd in the battery to beat because of having no bottom plate to support, utmost point ear fracture even. When the lower bus bar is installed, the lower bus bar can be directly installed on the lug without pushing the polar plate back and forth; and, separate lower busbar and polar plate through the bottom plate, avoid corroding the lower busbar because of the liquid outflow in the polar plate. In addition, the storage battery has a stable internal structure and is not easy to damage in the using process.

The utility model discloses in, upper cover 2 with the upper end of battery jar 1 matches, for the last busbar of further stabilizing the inside polar plate of battery and battery, preferably, as shown in fig. 10, the internal surface of upper cover 2 be provided with last busbar assorted upper groove 201 on battery jar 1 upper portion to and with anodal post, negative pole post assorted utmost point post hole 202. When the upper cover 2 is assembled with the upper part of the battery, the upper bus bar is clamped in the upper groove 301 on the inner surface of the upper cover 2, and the positive pole column and the negative pole column are clamped in the pole column hole 202, so that the bus bar and the pole column on the inner pole plate of the battery and the upper part of the battery can be stabilized, and the upper bus bar and the pole column can be protected. Further preferably, a plurality of sections of small grooves are formed in the upper groove 201 by separating plates, and each section of small groove is arranged corresponding to each section of upper bus bar, so as to further protect and support the upper bus bar.

In the present invention, the lower cover 3 is matched with the lower end of the battery jar 1, and in order to further stabilize the busbar of the internal polar plate of the battery and the lower part of the battery, preferably, as shown in fig. 11, the inner surface of the lower cover 3 is provided with a lower busbar matched lower groove 301 with the lower part of the battery jar 1. When the lower cover 3 is assembled with the bottom of the battery, the lower bus bar is clamped in the lower groove 301 on the inner surface of the lower cover 3, so that the internal pole plate of the battery and the lower bus bar of the battery can be stabilized, and the lower bus bar can be supported and protected. Further preferably, a plurality of sections of small grooves are formed in the lower groove 301 and separated by partition plates, and each section of small groove is arranged corresponding to each section of lower bus bar, so as to further protect and support the lower bus bar.

In the present invention, in order to improve the pressure-bearing capacity of the lower cover 3, preferably, a reinforcing rib 302 is further provided on the inner surface of the lower cover 3. The reinforcing ribs 302 include a first reinforcing rib arranged in parallel in the transverse direction and a second reinforcing rib arranged in parallel in the longitudinal direction, and the first reinforcing rib and the second reinforcing rib are perpendicularly intersected. The arrangement of the reinforcing ribs 302 can improve the bearing capacity of the lower cover 3, and prevent the lower cover 3 from deforming due to external force or the weight of the battery.

The utility model discloses in, polar plate 4 includes positive plate and negative plate, preferably, use the baffle to keep apart between positive plate and the negative plate, block. Illustratively, the surface of the electrode plate 4 is provided with a separator, the top and the bottom of the separator are respectively provided with holes corresponding to the lugs 5, and the lugs 5 respectively penetrate through the holes. The baffle that 4 surfaces of polar plate set up can be realized through the U template to polar plate 4 package piece, with U template upper portion uncovered, the lower part sets up the hole that supplies lower part utmost point ear to pass, puts into the U template with polar plate 4, and the utmost point ear of 4 lower parts of polar plate passes the hole. The separator can be arranged only on the positive plate or the negative plate, so long as the effect of separating the positive plate from the negative plate can be achieved.

In the present invention, the number and arrangement of the cells 101 can be selected according to the specific battery model, for example, the cells 101 can be arranged in a row in parallel, as shown in fig. 8; the cells 101 may also be of a 2 x 3 format.

The utility model discloses in, the uncovered and distance between the bottom plate 103 in upper end of battery jar 1 (being battery jar 1's inside degree of depth) makes the utmost point ear upper end of frame on polar plate 4 stretch out battery jar 1's upper end uncovered, does not influence on the busbar installation can.

In the present invention, it is preferable that each opening hole 102 is provided corresponding to each cell 101, that is, the lower tab of the electrode plate 4 in each cell 101 passes through the same opening hole 102. Specifically, as shown in fig. 9, the plurality of openings 102 are continuously arranged along the arrangement direction of the cells 101, the length C of the openings 102 along the arrangement direction of the cells 101 is equal to the width H of the cells 101, and the width H of the openings 102 is greater than the width n of the tab 5. In the preferred embodiment, the tab of the lower frame of the plate in each cell 101 passes through the same opening 102, and the opening 102 acts as a stop for the tab 5, so that the plate is more stable in the battery container 1.

The utility model discloses in, a plurality of utmost point crowd one-to-ones that constitute by a plurality of positive and negative polar plates set up in every single check 101, fix polar plate 4 in battery jar 1 through single check 101, through bottom plate 103 location polar plate 4 and support polar plate 4, utmost point crowd position can not change in the use, the position of utmost point ear 5 through trompil 102 location lower frame, under single check 101, trompil 102 and bottom plate 103 mutually support, utmost point crowd bottom is fixed in battery jar 1 bottom position, make utmost point crowd stable in structure in use and assembling process.

The utility model discloses in, the simple lattice 101 can be realized through setting up a plurality of division boards in the inside of battery jar 1.

The utility model discloses in, preferably, the homopolar busbar of 1 upper end of battery jar and lower extreme passes through wire 6 to be connected, and the positive bus-bar of upper end sets up a positive post and a negative pole post respectively to the external output department of negative bus-bar and the external output department. Namely, the lead-acid storage battery of the utility model only has the upper terminal, so as to avoid the danger of short circuit caused by the collision between the lower part of the battery and other conductive objects, and the lower terminal-free structure makes the battery simple, and the height of the battery which is increased by arranging the terminal can be avoided; the upper and lower bus bars with the same polarity are connected through the lead, so that the current distribution gradient difference of the upper and lower parts of the pole group can be reduced when the battery is charged and discharged in the production and life cycle, the current distribution balance of each part in the battery is improved, and the service life of the battery is prolonged.

The utility model discloses in, wire 6 can set up in battery jar 1's outside, also can set up in battery jar 1's inside. Further in view of safety, convenience and aesthetic appearance of the battery, in one embodiment, the lead 6 is located inside the battery container 1, i.e., the lead 6 connects the upper and lower homopolar busbars through the internal space of the battery container 1 (the structure of the lead 6 is shown outside the battery in the drawing for the purpose of illustrating the structure of the lead 6). The utility model discloses a set up wire 6 inside battery jar 1 and seal up the lower busbar of battery inside battery jar 1, the lower part does not have the terminal that leaks outward, can not take place the electric leakage between lower part terminal and water bath when becoming.

For example, a positive pole and a negative pole may be respectively disposed on the upper bus bar of the battery, and a positive pole and a negative pole may be respectively disposed on the lower bus bar of the battery, and the upper and lower poles with the same polarity are respectively connected by the wires 6. The upper and lower busbars may also be directly connected by wires 6. Preferably, a sealant is arranged at the connection part of the lead 6 and the upper and lower poles or the bus bar 7, so that poor contact and even disconnection of the connection point caused by chemical corrosion and battery chemical corrosion in the use process are prevented.

The utility model discloses in, to the setting of wire 6, in another kind of embodiment, the outer wall of battery jar 1 set up the outer wall recess and with outer wall recess assorted cover plate, wire 6 sets up in the outer wall recess, the cover plate lid is back on the outer wall recess, and the outer wall of battery jar 1 forms the complete plane with upper cover 2 and lower cover 3 matching. Preferably, the lead 6 is injected into the outer wall groove, and the cover plate and the outer wall groove are connected by sealant or welding, so that the lead 6 is ensured to be stabilized in the outer wall groove and not to fall off. In this embodiment, the lead 6 does not contact the electrode plate 4, thereby preventing the lead 6 from being damaged or short-circuited due to heat generation or leakage of the electrode plate 4.

The utility model discloses in, the last frame and the lower frame of polar plate can set up one or more utmost point ear respectively.

Illustratively, as shown in fig. 4, the upper frame and the lower frame of the plate 4 are respectively provided with one tab 5, and the tab 5 of the upper frame and the tab 5 of the lower frame are respectively located on two sides of the centerline of the plate 4. Preferably, the tabs 5 of the upper frame and the tabs 5 of the lower frame are respectively located on two sides of the center line of the plate 4 and have the same distance with the center line. Further preferably, the tabs of the upper frame and the tabs of the lower frame are located at diagonal positions.

Illustratively, the upper frame and the lower frame of the pole plate 4 are respectively provided with a plurality of tabs 5, and any two tabs 5 on the same frame are asymmetric with respect to the centerline of the pole plate 4. The upper frame and the lower frame are respectively provided with a plurality of lugs 5, and the voltage distribution at each position in the pole plate 4 is more uniform, so that the utilization rate of active substances at each position in the pole plate 4 tends to be the same, and the risk of failure of the pole plate 4 in advance due to overhigh local utilization rate is reduced. Any two lugs 5 on the same frame are asymmetric about the central line of the polar plate 4, so that the contact short circuit of the positive and negative busbars after the busbars are welded can be avoided.

For example, as shown in fig. 6, the upper frame and the lower frame of the plate are respectively provided with two tabs, the two tabs of the upper frame can be respectively denoted as a and B, the two tabs of the lower frame can be respectively denoted as a 'and B', the tab a of the upper frame of the plate is arranged on one side of the central line of the plate, the tab B of the upper frame of the plate is arranged on the other side of the central line of the plate, and the symmetric point of the tab a about the central line is not overlapped with the tab B; the pole lug A 'of the lower frame of the pole plate and the pole lug B of the upper frame of the pole plate are arranged on the same side of the central line of the pole plate, the pole lug B' of the lower frame of the pole plate and the pole lug A of the upper frame of the pole plate are arranged on the same side of the central line of the pole plate, and the symmetrical point of the pole lug A 'about the central line does not coincide with the pole lug B'. Two tabs on the same frame of the polar plate are respectively arranged on two sides of the central line, so that the electrical safety between the positive bus bar and the negative bus bar can be ensured besides the uniform utilization of active substances in the polar plate.

In order to further promote the uniform utilization of active materials in the plate, the distance between the lug A and the center line of the plate is preferably equal to the distance between the lug A 'and the center line of the plate, and the distance between the lug B and the center line of the plate is preferably equal to the distance between the lug B' and the center line of the plate.

In the utility model discloses in, "central line" refers to the connecting wire of the last frame mid point and the lower frame mid point of polar plate.

The utility model discloses in, as shown in fig. 5 and 7, when positive plate and negative plate staggered interval arrangement, make the utmost point ear of positive plate and negative plate stagger through the positive and negative two sides of adjustment polar plate to can not arouse the position conflict of anodal ear 501 and negative pole ear 502.

The utility model discloses in, for the convenience of battery and external connection, as shown in fig. 3, the battery still includes positive terminal and negative terminal, and positive terminal and negative terminal are connected with positive post and negative pole post through post hole 202 respectively.

The utility model discloses in, for further guarantee can not take place accidents such as electric leakage when becoming in the water bath, preferably, gap between lower cover 3 and lower busbar, gap between lower cover 3 and the battery jar 1 and the gap between lower cover 3 and the wire 6 set up sealed glue. In addition, in consideration of battery safety, sealants are also provided in the gap between the upper cover 2 and the upper bus bar, the gap between the upper cover 2 and the battery case 1, and the gap between the upper cover 2 and the lead 6. The utility model discloses in, because the bottom of battery jar 1 sets up bottom plate 103, can prevent sealed glue and the baffle contact on polar plate 4 surface to avoid the baffle to inhale and glue.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the present invention.

Claims (10)

1. A lead-acid storage battery is characterized by comprising a battery jar (1), an upper cover (2), a lower cover (3) and a polar plate (4) arranged in the battery jar (1), wherein the upper frame and the lower frame of the polar plate (4) are respectively provided with at least one polar lug (5); a plurality of single lattices (101) which are communicated with the upper end and the lower end of the interior of the battery jar (1) are arranged in the battery jar (1), the upper end of the battery jar (1) is open, the lower end of the battery jar (1) comprises a bottom plate (103), and a plurality of open holes (102) corresponding to the lugs (5) are formed in the bottom plate (103); the pole lug of the lower frame of the pole plate (4) penetrates through the opening (102) at the lower end of the battery jar (1), the lower frame of the pole plate (4) is in contact with the bottom plate (103), the homopolar pole lug at the upper end of the battery jar (1) is connected through the upper busbar, and the homopolar pole lug at the lower end of the battery jar (1) is connected through the lower busbar.

2. The lead-acid battery according to claim 1, characterized in that the upper cover (2) is fitted to the upper end of the battery container (1), and the inner surface of the upper cover (2) is provided with an upper groove (201) fitted to the upper bus bar of the upper portion of the battery container (1), and a post hole (202) fitted to the positive post and the negative post.

3. The lead-acid battery according to claim 1, characterized in that the lower cover (3) mates with the lower end of the battery well (1), the inner surface of the lower cover (3) being provided with a lower groove (301) that mates with the lower busbar of the lower part of the battery well (1).

4. A lead-acid battery according to claim 1, characterized in that said plates (4) comprise positive and negative plates separated by a separator.

5. The lead-acid battery according to claim 1, characterized in that a plurality of said openings (102) are arranged in series along the direction in which the cells (101) are arranged, the length C of said openings (102) in the direction in which the cells (101) are arranged being equal to the width H of the cells (101), the width H of said openings (102) being greater than the width n of the tabs (5).

6. The lead-acid battery according to claim 1, characterized in that the homopolar busbars of the upper and lower ends of the battery container (1) are connected by a wire (6), and a positive post and a negative post are respectively provided at the external output of the positive busbar and the external output of the negative busbar at the upper end.

7. Lead-acid battery according to claim 6, characterized in that the lead wire (6) is located inside the battery well (1).

8. The lead-acid storage battery according to claim 6, characterized in that the outer wall of the battery jar (1) is provided with an outer wall groove and a cover plate matched with the outer wall groove, the lead (6) is arranged in the outer wall groove, and after the cover plate is covered on the outer wall groove, the outer wall of the battery jar (1) forms a complete plane matched with the upper cover (2) and the lower cover (3).

9. The accumulator according to claim 1, characterized in that the upper and lower frames of the plate (4) are respectively provided with a tab (5), and the tabs (5) of the upper and lower frames are respectively located on both sides of the midline of the plate (4).

10. The accumulator according to claim 1, characterized in that the upper and lower frames of the plate (4) are respectively provided with a plurality of tabs (5), any two tabs (5) on the same frame being asymmetric with respect to the centerline of the plate (4).

Images