CN115395135A

CN115395135A - Power battery liquid cooling plate and forming method thereof

Info

Publication number: CN115395135A
Application number: CN202211064421.1A
Authority: CN
Inventors: 吴伟军; 王韬; 孙海东; 徐超强; 李博一; 程胜兵; 罗懿; 周宸; 蒋远富
Original assignee: Cornex New Energy Co ltd
Current assignee: Cornex New Energy Co ltd
Priority date: 2022-09-01
Filing date: 2022-09-01
Publication date: 2022-11-25

Abstract

The invention provides a power battery liquid cooling plate and a forming method thereof, and belongs to the technical field of new energy batteries. The liquid cooling plate of the power battery comprises a lower plate body, an upper plate body and an insulating support bar. The lower plate body is provided with a first plate surface and a second plate surface, and the first plate surface is provided with a plurality of first mounting holes and liquid cooling runners. The upper plate body is provided with a third plate surface and a fourth plate surface, and the third plate surface is provided with a water inlet, a water outlet and a plurality of second mounting holes. On the insulating support bar laminating was fixed in the third face, the quantity of insulating support bar had a plurality ofly, and a plurality of insulating support bars arrange into at least two sets ofly at the third face, and every insulating support bar of group all includes two at least insulating support bars that are parallel to each other and interval arrangement. By adopting the power battery liquid cooling plate and the forming method thereof, a flat reference can be formed on the contact surface of the liquid cooling plate and the battery membrane group, the contact integrity and the support stability are improved, and the heat dissipation and temperature equalization effects are further improved.

Description

Power battery liquid cooling plate and forming method thereof

Technical Field

The invention relates to the technical field of new energy batteries, in particular to a power battery liquid cooling plate and a forming method thereof.

Background

In the field of new energy batteries, in order to improve endurance, different numbers of battery cells are often connected in series and parallel to form a battery module so as to provide corresponding voltage or current for a load end to use. When the battery module works, the temperature rise of the battery is overhigh due to the high-rate charge and discharge, so that the performance, the service life and the like of the battery are influenced, and if the temperature rise cannot be effectively treated, even thermal runaway can be caused, so that the life safety of a user is endangered. Therefore, the battery module needs to be purposefully designed for heat dissipation and cooling to ensure normal work and prolong the service life.

In the correlation technique, to the battery module in the square aluminum-shell battery, generally adopt to set up the liquid cooling board by the concatenation of polylith extruded section bar and through the punching press brazing bottom the electric core that sets up side by side, utilize the inlet outlet of external water supply pipe and liquid cooling board to be connected and form the cooling water circulation, utilize the cooling water that flows in the runner in the liquid cooling board and carry out the heat transfer with electric core, realize the samming of dispelling the heat.

The liquid cooling plate and the battery module above the liquid cooling plate in the related art are generally adhered by coating a heat conductive adhesive. The whole liquid cooling board that relies on of battery module supports, and because the battery module is formed by the combination of plural electric core series-parallel connection, between the electric core of battery module and the electric core to and probably have certain assembly clearance between different electric cores and the liquid cooling board, cause unable complete contact between battery module or electric core and the liquid cooling board, lead to heat conduction efficiency not good, the heat dissipation samming effect is relatively poor.

Disclosure of Invention

The embodiment of the invention provides a liquid cooling plate of a power battery and a forming method thereof, which can form a flat reference on a contact surface of the liquid cooling plate and a battery membrane group, improve the contact integrity and the support stability, and further improve the heat dissipation and temperature equalization effects. The technical scheme is as follows:

in a first aspect, an embodiment of the present invention provides a power battery liquid cooling plate, including:

a lower plate body, an upper plate body and an insulating support bar,

the lower plate body is provided with a first plate surface and a second plate surface which are oppositely arranged, and the first plate surface is provided with a plurality of first mounting holes and liquid cooling runners;

the upper plate body has relative third face and the fourth face that sets up, have water inlet, delivery port on the third face and with a plurality of second mounting holes of a plurality of first mounting hole one-to-ones, the fourth face with first face laminating and fixed weld, the water inlet with the one end intercommunication in liquid cooling runner, the delivery port with the other end intercommunication in liquid cooling runner, the laminating of insulating support bar is fixed in on the third face, the quantity of insulating support bar has a plurality ofly, and is a plurality of insulating support bar is in third plate face is arranged into at least two sets ofly, every group insulating support bar all includes parallel and interval arrangement's at least two each other insulating support bar.

Optionally, the two ends of the insulation support bar deviate from the elastic mistake proofing films are respectively attached to the surfaces of the upper plate body and located at the two ends of the insulation support bar, and the colors of the elastic mistake proofing films are different.

Optionally, a plurality of strip-shaped sealing grooves are formed in one side plate surface of the lower plate body, and the plurality of strip-shaped sealing grooves are circumferentially arranged to surround the periphery of the liquid cooling flow channel.

Optionally, the edge joint of the lower plate body and the upper plate body is coated with a sealant. .

Optionally, the edge of lower plate body has a plurality of first limit holes that the indent set up, and is a plurality of first limit hole is followed the even interval arrangement in edge of lower plate body, the edge of going up the plate body has with a plurality of second limit holes of first limit hole one-to-one.

Optionally, the surface of the liquid cooling flow channel, which deviates from the lower plate body, is provided with supporting foam in an attaching manner.

Optionally, the power battery liquid cooling plate further comprises a water inlet plug and a water outlet plug, the water inlet plug is installed at the water inlet, and the water outlet plug is installed at the water outlet.

In a second aspect, an embodiment of the present invention further provides a forming method, for forming and manufacturing the power battery liquid cooling plate described in the foregoing first aspect, where the method includes:

stamping the upper plate body and the lower plate body on a whole plate;

the water inlet and the water outlet are punched at the edge of the plate surface of the upper plate body;

stamping the liquid cooling runner on the lower plate body by using a preset forming die;

superposing the lower plate body and the upper plate body, and simultaneously punching a plurality of first mounting holes and a plurality of second mounting holes;

and adhering the insulating support bar to the third plate surface of the upper plate body.

The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:

when carrying out the connection installation of battery module and power battery liquid cooling board, can form the cell type space that supplies the heat conduction to glue the coating between two adjacent insulating support bars, the staff can be to the coating heat conduction glue between the insulating support bar that the mutual interval set up. Simultaneously the top plane of insulating support bar can also regard as the coating benchmark of heat conduction glue, and the staff coats thickness and insulating support bar the same with heat conduction glue, also be insulating support bar's top plane parallel and level after, can place the battery module with last plate body on the bonding fixed. By adopting the power battery liquid cooling plate provided by the embodiment of the invention, the plurality of groups of insulating support bars are arranged on the upper plate body, so that a flat reference and an additional support point can be formed on the contact surface of the liquid cooling plate and the battery membrane group, the heat-conducting glue coated between the liquid cooling plate and the battery membrane group can have a consistent thickness, the contact integrity and the support stability between the liquid cooling plate and the battery module group are improved, and the heat dissipation and temperature equalization effects are further improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is an exploded perspective view of a liquid cooling plate of a power battery according to an embodiment of the present invention;

fig. 2 is a schematic top view of a lower plate according to an embodiment of the present invention;

fig. 3 is a schematic top view of an upper plate according to an embodiment of the present invention;

fig. 4 is a schematic perspective view of an upper plate according to an embodiment of the present invention;

FIG. 5 is a schematic top view of the insulating support bars as shown at M in FIG. 3;

FIG. 6 is a schematic view of a partial enlarged structure at N in FIG. 5;

fig. 7 is a schematic cross-sectional structural view of a power battery liquid cooling plate provided in an embodiment of the present invention;

FIG. 8 is a schematic view of a partial enlarged structure as at A in FIG. 7;

FIG. 9 is a schematic view of a partial enlarged structure at B in FIG. 7;

fig. 10 is a flow chart of a molding method according to an embodiment of the present invention.

In the figure:

1-lower plate body; 2-an upper plate body; 3-insulating support bars; 4-supporting foam; 5-water inlet plug; 6-water outlet plug; 11-a first mounting hole; 12-a liquid cooling flow path; 13-strip-shaped sealing grooves; 14-a first edge hole; 21-a water inlet; 22-a water outlet; 23-a second mounting hole; 24-a second side hole; 31-elastic error-proofing film; 1 a-a first board surface; 1 b-a second board surface; 2 a-a third board surface; 2 b-fourth panel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The liquid cooling plate and the battery module above the liquid cooling plate in the related art are generally bonded by coating a heat conductive adhesive. The whole liquid cooling board that relies on of battery module supports, and because the battery module is formed by the combination of plural electric core series-parallel connection, between the electric core of battery module and the electric core to and probably have certain assembly clearance between different electric cores and the liquid cooling board, cause unable complete contact between battery module or electric core and the liquid cooling board, lead to heat conduction efficiency not good, the heat dissipation samming effect is relatively poor.

Fig. 1 is an exploded perspective view of a liquid cooling plate of a power battery according to an embodiment of the present invention. Fig. 2 is a schematic top view of a lower plate according to an embodiment of the present invention. Fig. 3 is a schematic top view of an upper plate according to an embodiment of the present invention. Fig. 4 is a schematic perspective view of an upper plate body according to an embodiment of the present invention. Fig. 5 is a schematic top view of the insulating support bar shown at M in fig. 3. Fig. 6 is a schematic view of a partial enlarged structure at N in fig. 5. Fig. 7 is a schematic cross-sectional structural diagram of a power battery liquid cooling plate according to an embodiment of the present invention. Fig. 8 is a partially enlarged schematic view of a structure as shown at a in fig. 7. Fig. 9 is a partial enlarged schematic structural view as shown at B in fig. 7. By practice, the applicant provides a power battery liquid cooling plate comprising a lower plate body 1, an upper plate body 2 and an insulating support bar 3.

The lower plate 1 has a first plate 1a and a second plate 1b which are oppositely arranged, and the first plate 1a has a plurality of first mounting holes 11 and liquid cooling channels 12.

The upper plate body 2 is provided with a third plate surface 2a and a fourth plate surface 2b which are oppositely arranged, the third plate surface 2a is provided with a water inlet 21, a water outlet 22 and a plurality of second mounting holes 23 which correspond to the first mounting holes 11 one to one, the fourth plate surface 2b is attached to the first plate surface 1a and fixedly welded, the water inlet 21 is communicated with one end of the liquid cooling flow channel 12, and the water outlet 22 is communicated with the other end of the liquid cooling flow channel 12. On insulating support bar 3 laminating was fixed in third board face 2a, insulating support bar 3's quantity had a plurality ofly, and a plurality of insulating support bars 3 arrange into at least two sets ofly at third board face 2a, and every group insulating support bar 3 all includes two at least insulating support bars 3 that are parallel to each other and interval arrangement. .

In the embodiment of the invention, the power battery liquid cooling plate is formed by splicing and welding a lower plate body 1 and an upper plate body 2. After splicing, a plurality of first mounting holes 11 on the lower plate body 1 and a plurality of second mounting holes 23 on the upper plate body 2 are aligned one by one, and a worker can fixedly install the whole power battery liquid cooling plate on a battery box bottom protection plate of a vehicle through the second mounting holes 23 and the first mounting holes 11 through bolts. And then, a plurality of groups of insulating support bars 3 are attached to the third plate surface 2a of the upper plate body 2 one by one, namely the top plate surface. When carrying out the connection installation of battery module and power battery liquid cooling board, can form the cell type space that supplies the heat conduction to glue the coating between two adjacent insulating support strips 3, the staff can be to the coating heat conduction glue between the insulating support strip 3 that the mutual interval set up. Simultaneously insulating support bar 3's top plane can also regard as the coating benchmark of heat conduction glue, and the staff coats thickness and insulating support bar 3 with heat conduction glue and is the same, also be insulating support bar 3's top plane parallel and level after, can place the battery module with go up on plate body 2 and carry out the bonding fixed. The liquid cooling runner 12 formed by punching on the lower plate body 1 can be connected with a water cooling circulating pipeline of a vehicle through the water inlet 21 and the water outlet 22 on the upper plate body 2, cooling water is introduced into the liquid cooling runner 12, and heat exchange and temperature equalization are carried out on the liquid cooling runner and the battery module by utilizing flowing cooling water through heat-conducting glue between the upper plate body 2 and the battery module. By adopting the power battery liquid cooling plate provided by the embodiment of the invention, the plurality of groups of insulating support bars 3 are arranged on the upper plate body 2, so that a flat reference and an additional support point can be formed on the contact surface of the liquid cooling plate and the battery membrane group, the heat-conducting glue coated between the liquid cooling plate and the battery membrane group can have consistent thickness, the contact integrity and the support stability between the liquid cooling plate and the battery module group are improved, and the heat dissipation and temperature equalization effects are further improved.

Exemplarily, in the present embodiment, the insulation support bar 3 is a plastic piece.

Optionally, the surfaces of the two ends of the insulating support bar 3, which face away from the upper plate body 2, are respectively adhered with elastic error-proofing films 31, and the colors of the elastic error-proofing films 31 at the two ends of the insulating support bar 3 are different. For example, since the battery module disposed on the upper plate 2 is generally composed of a plurality of battery cells connected in series and in parallel, the installation orientation of the positive and negative poles at the tops of the battery cells needs to be considered when the battery module is placed in the battery box. If the orientation is reversed, the bottom of the battery module is fixedly bonded with the liquid cooling plate, so that the battery module is difficult to disassemble and assemble again, and the overall installation efficiency is affected. In the embodiment of the invention, the elastic error-proofing films 31 with different colors are respectively attached to the outer surfaces of the two ends of the insulating support bar 3, the different colors correspond to the positive and negative poles at the top of the electric core arranged on the insulating support bar 3 one by one, and workers or robots performing assembly procedures can be prompted by the different colors, so that visual error proofing is provided, and the battery module is prevented from being oriented wrongly when being connected and installed with the liquid cooling plate. The practicability of the liquid cooling plate of the power battery is improved.

It should be noted that the elastic error-proofing film 31 made of elastic material, such as a soft foam film, may also have a certain buffering and supporting effect between the insulating support bars 3 and the battery modules, so as to slow down the vibration impact on the liquid-cooled plate and the battery modules during the operation of the vehicle.

Optionally, a plurality of strip-shaped sealing grooves 13 are formed in one side plate surface of the lower plate 1, and the plurality of strip-shaped sealing grooves 13 are circumferentially arranged to surround the periphery of the liquid cooling flow passage 12. Illustratively, in the embodiment of the present invention, at least one strip-shaped sealing groove 13 is additionally stamped and arranged between the periphery of the liquid cooling flow channel 12 and the edge of the lower plate body 1, and after the lower plate body 1 and the upper plate body 2 are welded together. If the bolt fastening of second mounting hole 23 and first mounting hole 11 is not in place, or when the gap appears because of external reasons such as vibration in the connection between plate body 1 and the last plate body 2 after long-time use, the cooling water that is arranged in liquid cooling runner 12 can preferentially dip in bar seal groove 13 after oozing to avoid the cooling water further oozing the marginal outside of plate body 1 and the last plate body 2 down and drip inside the battery case, improved power battery liquid cooling board's leakproofness and security.

Illustratively, in the embodiment of the present invention, one strip-shaped sealing groove 13 is formed at a part of the side edge outside the liquid-cooling flow passage 12, and three or four strip-shaped sealing grooves 13 are sequentially formed at the other part of the side edge, which is adaptively set based on the distance between the edge of the lower plate 1 and the liquid-cooling flow passage 12. In the covering and enveloping space of the liquid cooling plate, after the flow channel setting of the liquid cooling flow channel 12 is obtained through the simulation of the flow field of the water cooling plate, the strip-shaped sealing grooves 13 are arranged in the rest plate body space as much as possible and as long as possible, so that a larger leakage storage space is obtained. Meanwhile, the long strip-shaped sealing groove 13 can be punched and molded, and can be used as a structure similar to a reinforcing rib under the condition that cooling water is not permeated, so that the integral mechanical strength of the liquid cooling plate is improved.

Optionally, the joint of the edges of the lower plate 1 and the upper plate 2 is coated with a sealant. Illustratively, in the embodiment of the invention, after the lower plate body 1 and the upper plate body 2 are welded together, a layer of sealant is coated at the joint of the edges of the lower plate body 1 and the upper plate body 2, so that the situation that cooling water seeps out of the edges of the lower plate body 1 and the upper plate body 2 and drops into the battery box can be further avoided, and the sealing effect is further improved.

Optionally, the edge of the lower plate 1 has a plurality of first edge holes 14 disposed in a concave manner, the plurality of first edge holes 14 are uniformly spaced along the edge of the lower plate 1, and the edge of the upper plate 2 has a plurality of second edge holes 24 corresponding to the plurality of first edge holes 14 one to one. Illustratively, in the embodiment of the invention, the concave structure composed of the first side hole 14 and the second side hole 24 is formed at the edge of the outer ring of the power battery liquid cooling plate, so that a space for providing a relief space is provided for installing other parts on the bottom protection plate inside the battery box, the risks of interference and infirm installation in the assembly are avoided, and the assembly stability of the power battery liquid cooling plate is improved.

Optionally, the surface of the liquid cooling flow passage 12 facing away from the lower plate 1 is adhered with supporting foam 4. Exemplarily, in the embodiment of the present invention, the supporting foam 4 is attached to the surface of the liquid cooling flow channel 12 away from the lower plate 1, that is, the surface for contacting with the bottom protection plate of the battery box, so as to play a role of buffering and supporting, prevent the liquid cooling plate body from being scratched and damaged due to contact friction caused by vibration when the liquid cooling plate body directly contacts with the battery box during operation, and effectively prolong the service life of the liquid cooling plate of the power battery.

Optionally, the power battery liquid cooling plate further includes a water inlet plug 5 and a water outlet plug 6, the water inlet plug 5 is installed at the water inlet 21, and the water outlet plug 6 is installed at the water outlet 22. Illustratively, in the embodiment of the invention, during the transportation and storage of the liquid cooling plate before the liquid cooling plate is assembled to the battery box of the vehicle after preparation, the water inlet 21 and the water outlet 22 are respectively blocked by the water inlet plug 5 and the water outlet plug 6, so as to achieve the effect of isolating external dust or foreign matters and avoid affecting the circulation of cooling water after assembly.

Fig. 10 is a flow chart of a molding method according to an embodiment of the present invention. As shown in fig. 10, an embodiment of the present invention further provides a molding method for molding and manufacturing the power battery liquid cooling plate shown in fig. 1 to 9, where the molding method includes:

s1, an upper plate body 2 and a lower plate body 1 are punched on a whole plate.

Specifically, in the embodiment of the present invention, the outer contours of the upper plate body 2 and the lower plate body 1 are the same, and the same set of mold can be used to punch and form the raw material plate.

S2, punching a water inlet 21 and a water outlet 22 on the edge of the plate surface of the upper plate body 2.

And S3, punching a liquid outlet flow channel 12 on the lower plate body 1 by using a preset forming die.

Specifically, in the embodiment of the present invention, the flow channel arrangement of the liquid cooling flow channel 12 is obtained through the water cooling plate flow field simulation, and the corresponding upper and lower stamping dies are manufactured. And placing the flat lower plate body 1 between the upper die and the lower die for die assembly and stamping, and stamping a liquid outlet flow channel 12 on the lower plate body 1.

For example, in the embodiment of the present invention, the strip-shaped sealing groove 13 also located on the lower plate 1 may be designed together with the liquid cooling channel 12 and may be formed by stamping through the same set of upper and lower dies.

And S4, overlapping the lower plate body 1 and the upper plate body 2, and simultaneously punching a plurality of first mounting holes 11 and a plurality of second mounting holes 23.

And S5, adhering the insulation support bars 3 to the third plate surface 2a of the upper plate body 2.

Specifically, in the embodiment of the present invention, the supporting foam 4 may also be adhered to the third board surface 2a of the lower board 1 after the above steps are completed.

Adopt this power battery liquid cold drawing and above-mentioned forming method, compare with traditional power battery liquid cold drawing in the correlation technique, through set up multiunit insulating support bar 3 on last plate body 2, can form smooth benchmark and extra strong point on the contact surface of liquid cold drawing and battery membrane group, make the heat-conducting glue of coating between can have unanimous thickness, improve contact integrality and support stability between liquid cold drawing and the battery module, and then improve the samming effect of dispelling the heat.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description and claims of the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, which may also change accordingly when the absolute position of the object being described changes.

The invention is not to be considered as limited to the particular embodiments shown and described, but is to be understood that various modifications, equivalents, improvements and the like can be made without departing from the spirit and scope of the invention.

Claims

1. A power battery liquid cooling plate, comprising: a lower plate body (1), an upper plate body (2) and an insulating support bar (3),

the lower plate body (1) is provided with a first plate surface (1 a) and a second plate surface (1 b) which are oppositely arranged, and the first plate surface (1 a) is provided with a plurality of first mounting holes (11) and liquid cooling runners (12);

go up plate body (2) third face (2 a) and fourth face (2 b) that have relative setting, third face (2 a) go up water inlet (21), delivery port (22) and with a plurality of second mounting holes (23) of a plurality of first mounting holes (11) one-to-one, fourth face (2 b) with laminating and fixed weld of first face (1 a), water inlet (21) with the one end intercommunication of liquid cooling runner (12), delivery port (22) with the other end intercommunication of liquid cooling runner (12), insulating support bar (3) laminating is fixed in on third face (2 a), the quantity of insulating support bar (3) has a plurality ofly, and is a plurality of insulating support bar (3) are in third face (2 a) are arranged into at least two sets ofly, every group insulating support bar (3) all include parallel and at least two of interval arrangement each other insulating support bar (3).

2. The power battery liquid cooling plate according to claim 1, characterized in that elastic error-proofing films (31) are respectively attached to the surfaces of the two ends of the insulating support bars (3) which are far away from the upper plate body (2), and the colors of the elastic error-proofing films (31) at the two ends of the insulating support bars (3) are different.

3. The power battery liquid cooling plate according to claim 1, wherein a plurality of strip-shaped sealing grooves (13) are formed in one side plate surface of the lower plate body (1), and the plurality of strip-shaped sealing grooves (13) are circumferentially arranged to enclose the periphery of the liquid cooling flow channel (12).

4. The power battery liquid cooling plate according to claim 3, characterized in that the edge joints of the lower plate body (1) and the upper plate body (2) are coated with a sealant.

5. The power battery liquid cold plate according to claim 1, characterized in that the edge of the lower plate body (1) is provided with a plurality of first edge holes (14) which are concavely arranged, the plurality of first edge holes (14) are uniformly arranged at intervals along the edge of the lower plate body (1), and the edge of the upper plate body (2) is provided with a plurality of second edge holes (24) which correspond to the plurality of first edge holes (14) in a one-to-one manner.

6. The power battery liquid cooling plate according to claim 1, characterized in that the surface of the liquid cooling flow channel (12) facing away from the lower plate body (1) is adhered with supporting foam (4).

7. The power battery liquid cooling plate according to claim 1, further comprising a water inlet plug (5) and a water outlet plug (6), wherein the water inlet plug (5) is installed at the water inlet (21), and the water outlet plug (6) is installed at the water outlet (22).

8. A molding method for molding and manufacturing the power battery liquid cooling plate according to any one of claims 1 to 7, wherein the molding method comprises the following steps:

stamping the upper plate body (2) and the lower plate body (1) on a whole plate;

the water inlet (21) and the water outlet (22) are punched at the edge of the plate surface of the upper plate body (2);

stamping the liquid cooling runner (12) on the lower plate body (1) by using a preset forming die;

superposing the lower plate body (1) and the upper plate body (2), and simultaneously punching a plurality of first mounting holes (11) and a plurality of second mounting holes (23);

and adhering the insulation support bars (3) to the third plate surface (2 a) of the upper plate body (2).