CN110696927A

CN110696927A - Automobile A column

Info

Publication number: CN110696927A
Application number: CN201911150433.4A
Authority: CN
Inventors: 张雪亮
Original assignee: Aiways Automobile Co Ltd
Current assignee: Aiways Automobile Co Ltd
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2020-01-17
Anticipated expiration: 2039-11-21
Also published as: CN110696927B

Abstract

The invention relates to an automobile A-pillar, which comprises a hollow cavity with a closed cross section and a structure-reinforced filler arranged in the hollow cavity and used for supporting the inner wall of the hollow cavity. The structure-reinforced filler is filled into the hollow cavity, so that the sectional area of the A column can be reduced to the maximum extent on the basis of ensuring the light weight of the vehicle body, the visual obstacle angle of the A column is reduced, and the turning sight of a driver is favorably ensured; the structural strength and rigidity of the A column are further enhanced by using the structural reinforcing filler on the basis of greatly reducing the using amount of steel, so that the A column can meet the strength requirement during collision of a vehicle body, particularly the strength requirement during front collision and small offset collision and the jacking rigidity requirement of the vehicle body, and the personal safety of a driver is favorably ensured. The filling condition of the filler is enhanced by changing the structure in the hollow cavity, so that the hollow cavity with the same specification can meet the A collision requirements of different vehicle types, and the hollow cavity has the characteristics of strong applicability and low comprehensive cost.

Description

Automobile A column

Technical Field

The invention belongs to the technical field of vehicle structures, and particularly relates to an automobile A column.

Background

The preparation of the A column of the automobile is generally that high-strength steel or ultrahigh-strength steel is punched and pressed into an upper side beam reinforcing plate and an upper side beam inner plate, and then the connecting edge of the upper side beam reinforcing plate and the upper side beam inner plate is spot-welded to form a cavity; and the section of the column A is large, so that the obstacle angle of the column A is large, the turning sight of a driver is shielded, and potential safety hazards exist.

In order to reduce the sectional area of the A column, the prior art also discloses a tubular A column, namely a hollow section with a closed cross section, and although the structure reduces the using amount of steel and the sectional area of the A column, the structure is beneficial to the light weight of a vehicle body assembly and the obstacle angle of the A column, when the A column bears larger collision energy, the hollow A column structure is easy to deform obviously and even break, so that the personal safety of a driver is threatened.

Disclosure of Invention

In order to solve part or all of the problems, the invention provides an automobile A-pillar which can meet the requirements of rigidity and strength of an automobile body on the basis of ensuring the light weight of the automobile body and has a small A-pillar obstacle angle to ensure the turning sight of a driver.

The invention provides an automobile A column, which comprises a hollow cavity with a closed cross section and a structure-reinforced filler arranged in the hollow cavity and used for supporting the inner wall of the hollow cavity.

Further, the filling form of the structural reinforcing filler in the hollow cavity can be whole cavity filling or sectional filling; the hollow cavity is an inner high-pressure forming part or a roll bending part.

Further, still including set up in hollow cavity upside and be used for to in the hollow cavity pour into the sprue of structure reinforcing filler and be used for the first sealing of encapsulation the sprue.

Furthermore, the structure reinforcing filler also comprises a blocking plate arranged in the hollow cavity at intervals, the blocking plate can block the hollow cavity into filling cavities for filling the structure reinforcing filler, and each filling cavity is provided with one corresponding injection port.

Further, still including set up in fill the chamber upside and keep away from the gas vent of filling the mouth and be used for the encapsulation the second sealing of gas vent.

Further, the structural reinforcing filler is a non-newtonian fluid.

Further, the structural reinforcing filler is a structural foam, which is polyurethane or epoxy.

The hollow cavity comprises a first upper inclined plate, a first lower inclined plate, a second lower inclined plate and a second upper inclined plate which are connected end to end; the side wall outer plate comprises a third upper inclined plate parallel to the second upper inclined plate, a third lower inclined plate which is connected with the third upper inclined plate and parallel to the second lower inclined plate, a first bent edge connected with the upper right end of the third upper inclined plate and a second bent edge connected with the lower right end of the third lower inclined plate; the parallel distance between the third upper inclined plate and the second upper inclined plate is 3-10mm, and the parallel distance between the third lower inclined plate and the second lower inclined plate is 3-10 mm.

Further, still include with the inner panel that hollow cavity links to each other and is used for connecting B post or C post, the inner panel include with the third crimp that the first crimp of side wall planking links to each other, with the fourth crimp that the second crimp links to each other and connect the straight board of third crimp and fourth crimp, straight board with hollow cavity's first lower inclined plate is close neighbour.

Furthermore, the length of the inner plate is smaller than that of the hollow cavity, and the first bent edge of the side-wall outer plate is connected with the first upper inclined plate of the hollow cavity at a position far away from the inner plate.

The invention provides an automobile A column, which adopts a structure-reinforced filler filled into a hollow cavity, and can reduce the cross-sectional area of the A column to the maximum extent on the basis of ensuring the light weight of an automobile body, thereby further reducing the visual obstacle angle of the A column and being beneficial to ensuring the turning sight of a driver; the use of the structure-reinforced filler further enhances the structural strength and rigidity of the A column on the basis of greatly reducing the use amount of steel, reduces the possibility of serious deformation of the A column due to collision to a certain extent, improves the performances of the A column in front collision and small offset collision of an automobile, greatly improves the collision performance of the automobile and the jacking rigidity of an automobile body, and is beneficial to ensuring the personal safety of a driver. The hollow cavity body with the same specification can meet the A-column collision requirements of different vehicle types by changing the filling condition of the structure reinforcing filler in the hollow cavity body, has the characteristics of simple structure, strong universality and low comprehensive cost, and is suitable for popularization and application.

Drawings

In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

FIG. 1 is a schematic perspective view of an A-pillar of an automobile according to an embodiment of the present invention;

FIG. 2 is a first cross-sectional view of the hollow chamber of FIG. 1 taken along the line A-A;

FIG. 3 is a second cross-sectional view of the hollow chamber of FIG. 1 taken along the line A-A;

FIG. 4 is a schematic view of a partial installation of the A-pillar of the vehicle of FIG. 1 on a vehicle;

FIG. 5 is a cross-sectional view of the A-pillar of the vehicle of FIG. 4 taken along the direction B-B;

fig. 6 is a cross-sectional view of the a-pillar of the vehicle shown in fig. 4 taken along the direction C-C.

Description of reference numerals: an automotive a-pillar 100; the structure comprises a hollow cavity 1, a filling cavity 101, a non-filling cavity 102, a first upper inclined plate 111, a first lower inclined plate 112, a second lower inclined plate 113, a second upper inclined plate 114, an injection port 105, an exhaust port 106, a structure-reinforced filler 2, a side wall outer plate 3, a third upper inclined plate 301, a third lower inclined plate 302, a first bent edge 303, a second bent edge 304, a blocking plate 4, an inner plate 5, a third bent edge 501, a fourth bent edge 502 and a straight plate 503.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

As shown in fig. 1, the present embodiment provides an a-pillar 100 for an automobile, which includes a hollow cavity 1 having a closed cross section, and a structural reinforcing filler 2 disposed in the hollow cavity 1 and supporting an inner wall of the hollow cavity 1. The hollow cavity 1 is filled with the structure-reinforced filler 2, so that the sectional area of the A column can be reduced to the maximum extent on the basis of ensuring the light weight of the vehicle body, the visual obstacle angle of the A column is further reduced, and the turning sight of a driver is favorably ensured; the structural reinforcing filler 2 is used for further reinforcing the structural strength and rigidity of the A column on the basis of greatly reducing the using amount of steel, the possibility of serious deformation of the A column due to collision is reduced to a certain degree, particularly, the performance of the A column in front collision and small offset collision of an automobile is improved, the collision performance of the automobile and the jacking rigidity of an automobile body are greatly improved, and the personal safety of a driver is favorably ensured. The automobile A column 100 has a simple structure, greatly reduces the consumption of steel, is beneficial to energy conservation and consumption reduction, and is suitable for popularization and application.

In the embodiment, the filling form of the structure-reinforced filler 2 in the hollow cavity 1 can be whole cavity filling or sectional filling, and sectional filling is preferably performed in combination with the stress condition of the column A during vehicle body collision, namely, local filling is performed at the main stress position of the column A, so that the structural strength of the column A at the main stress position can be ensured, and the light weight of a vehicle body is facilitated.

Referring to fig. 2 and 3, the automobile a-pillar in the embodiment further includes an injection port 105 disposed on the upper side of the hollow cavity 1 and used for injecting a structure-enhancing filler into the hollow cavity 1 and a first sealing portion for sealing the injection port 105, the structure-enhancing filler is injected into the hollow cavity 1 through a plurality of injection ports disposed at intervals, so that segmented filling in the hollow cavity 1 can be realized, and after the structure-enhancing filler is filled, the injection port is sealed by the first sealing portion, thereby preventing external dust from entering the hollow cavity through the injection port. The first sealing portion in this embodiment may be made of rubber or metal that is screwed to the inlet.

The structural reinforcing filler in the embodiment can be non-Newtonian fluid or structural foam, the structural strength and the rigidity of the structural reinforcing filler are different due to the non-Newtonian fluid or the structural foam made of different materials, and the filling form of the structural reinforcing filler in the cavity of the A column is different due to the characteristics of the material, so that the structural reinforcing filler in the embodiment can be filled with different materials and structures according to the actual requirement on the strength of the vehicle body.

In one embodiment, referring to FIG. 2, when the structural reinforcing filler is a non-Newtonian fluid, due to the fluidity of the non-Newtonian fluid, it is necessary to prepare a plurality of filling chambers for filling the non-Newtonian fluid in the cavity of the A-pillar, and then fill the non-Newtonian fluid into the filling chambers. Therefore, the a-pillar of the vehicle in this embodiment further includes a blocking plate 4 disposed at an interval in the hollow cavity 1, the blocking plate 4 can block the hollow cavity 1 into filling cavities 101 for filling the structural reinforcing filler, and each filling cavity 101 has one injection port 105. The filling device further comprises an exhaust port 106 arranged on the upper side of the filling cavity 101 and far away from the injection port 105, and a second sealing part for sealing the exhaust port 106. The structural design of the blocking plate 4 plays a role in locally supporting the inner wall of the hollow cavity 1 on one hand, and plays a role in blocking the inner cavity of the hollow cavity 1 on the other hand. The inlet 105 and the outlet 106 disposed on the upper side of the filling cavity 101 are beneficial to complete smooth filling of the non-newtonian fluid in the filling cavity 101 and discharging of gas in the cavity, and after the non-newtonian fluid is filled, the inlet 105 and the outlet 106 are sealed to prevent the non-newtonian fluid from leaking.

In the present embodiment, the hollow cavity 1 further includes a non-filled cavity 102 spaced from the filled cavity 101, the filled cavity 101 is disposed at a position of the a-pillar where the filled cavity mainly receives the collision force, and the non-filled cavity 102 is disposed at a position of the a-pillar where the non-filled cavity mainly receives the collision force. The lengths of the filling cavity 101 and the non-filling cavity 102 are determined by the area of the force-receiving position of the a column, for example, if the area of a certain force-receiving position is large, the length of the filling cavity 101 corresponding to the position is set to be long, and if the area of a certain force-receiving position is small, the length of the filling cavity 101 corresponding to the position is set to be short.

The unfilled cavity 102 may be filled with a material other than a non-newtonian fluid, such as a structural foam, to enhance the support strength of the a-pillar.

The non-Newtonian fluid in the embodiment is a fluid which does not satisfy the Newton viscosity experiment law, namely, the shear stress and the shear strain rate are not in a linear relation, and when the fluid is slowly stressed, the fluid has liquid characteristics and flexibility; non-newtonian fluids have solid-state-like behavior when subjected to transient violent impacts, with high strength and high elasticity. In the embodiment, when the outer wall of the filling cavity 101 filled with the non-newtonian fluid is severely collided, the non-newtonian fluid has solid-state-like characteristics, and is high in strength and elasticity, and the resistance of the non-newtonian fluid to collision energy is sharply increased, so that the structural strength and rigidity of the filling cavity 101 can be enhanced by the non-newtonian fluid filled in the filling cavity 101 when the automobile A-pillar 100 is severely collided with an automobile body, and the safety of drivers in an automobile can be guaranteed; similarly, when the outer wall of the filling cavity 101 filled with the non-newtonian fluid is subjected to a small collision impact force, the non-newtonian fluid can absorb collision energy in the collision process of the vehicle body, so that the occurrence of the collision deformation of the a-pillar is reduced.

Common industrial non-newtonian fluids include concentrated solutions and suspensions of high molecular polymers, such as polyethylene, polyacrylamide, polyvinyl chloride, nylon 6, PVS, celluloid, dacron, rubber solutions, various engineering plastics, melts and solutions of chemical fibers. In practical applications, the non-newtonian fluid is usually a mixture of two or more kinds to satisfy a series of performances of high and low temperature resistance, corrosion resistance, aging resistance, etc. of vehicles.

In another embodiment, referring to fig. 3, when the structural reinforcing filler is structural foam, due to the characteristic of fast curing after the structural foam is filled, a filling cavity does not need to be prepared in the cavity of the a-pillar of the automobile, and the structural foam is injected into the cavity through the injection port 105 only at the position where the structural foam needs to be filled, so that the structural foam can be rapidly cured in the cavity of the a-pillar, and further the function of enhancing the supporting strength of the a-pillar is achieved, the possibility of serious deformation of the a-pillar due to collision is reduced to a certain extent, particularly the performance of the a-pillar during front collision and small offset collision of the automobile is improved, and the collision performance of the automobile and the jacking rigidity of the automobile body are greatly improved. The preferred structural foam in this embodiment is polyurethane or epoxy. Can play a role in supporting the inner wall of the filling cavity 101 so as to increase the structural strength of the filling cavity 101, can ensure that the automobile A column 100 is not easy to deform under the action of larger impact force,

based on different automobile body structures different to the crashworthiness demand of automobile body, especially the required collision strength of car A post is different, this A post structural design who just makes different cars is very different, leads to the structural configuration of car A post in the market various, and at the bottom of the universalization degree, is unfavorable for the volume production. In a specific embodiment, because a large-area battery pack is mounted at the bottom of a new energy electric automobile, the requirements of the electric automobile and a traditional fuel automobile on the collision capacity of the automobile body are different, especially the required collision strength of an automobile A column is different, and the structural design of the automobile A column of the electric automobile and the traditional fuel automobile is greatly different. This application can set up the packing chamber of isostructure and pack the non-Newtonian fluid of different materials or directly fill the structure foam in the hollow cavity of A post through filling opening 105 to the A post at the packing intracavity according to the intensity demand of car collision in the hollow cavity of car A post, this hollow cavity structure that just makes same specification can satisfy the A post collision demand of different cars, do benefit to the universalization degree that improves this application car A post, easily realize the mass production of car A post hollow cavity, the preparation cost of car has been reduced by a wide margin, easily widely popularize and apply.

Referring to fig. 4 and 5, the hollow chamber 1 in the present embodiment includes a first upper inclined plate 111, a first lower inclined plate 112, a second lower inclined plate 113 and a second upper inclined plate 114 which are connected end to end, an included angle between the first upper inclined plate 111 and the second upper inclined plate 114 depends on a specific vehicle body structure design, and an included angle between the first lower inclined plate 112 and the second lower inclined plate 113 also depends on a specific vehicle body structure design, and is not limited to the shape and the angle shown in fig. 5.

The automobile a-pillar 100 in this embodiment further includes a side-wall outer panel 3 connected to the hollow cavity 1, the side-wall outer panel 3 includes a third upper inclined panel 301 parallel to the second upper inclined panel 114, a third lower inclined panel 302 connected to the third upper inclined panel 301 and parallel to the second lower inclined panel 113, a first bent edge 303 connected to an upper right end of the third upper inclined panel 301, and a second bent edge 304 connected to a lower right end of the third lower inclined panel 302; the parallel distance between the third upper inclined plate 301 and the second upper inclined plate 114 is 3-10mm, and the parallel distance between the third lower inclined plate 302 and the second lower inclined plate 113 is 3-10 mm. The specific arrangement of the parallel distance between the third upper swash plate 301 and the second upper swash plate 114 and the parallel distance between the third lower swash plate 302 and the second lower swash plate 113 in the present embodiment depends on the specific vehicle body mechanism, and is not limited thereto.

The hollow cavity 1 in the embodiment plays a role in supporting the side wall outer plate 3, when an automobile is laterally collided, the third upper inclined plate 301 and the third lower inclined plate 302 of the side wall outer plate 3 are direct stress ends, the third upper inclined plate 301 is arranged to be parallel to the second upper inclined plate 114 of the hollow cavity 1, so that the collision impact force borne by the third upper inclined plate 301 of the side wall outer plate 3 can be well transmitted to the second upper inclined plate 114, and a mounting gap larger than 3mm is reserved between the third upper inclined plate 301 and the second upper inclined plate 114, so that the hollow cavity is favorable for buffering collision energy and can play a certain energy absorption effect; in a similar way, the third lower inclined plate 302 is parallel to the second lower inclined plate 113 of the hollow cavity 1, so that the collision impact force borne by the third lower inclined plate 302 of the side wall outer plate 3 can be well transmitted to the second lower inclined plate 113, and a mounting gap larger than 3mm is reserved between the third lower inclined plate 302 and the second lower inclined plate 113, so that the buffer effect on collision energy is facilitated, and a certain energy absorption effect can be achieved. Meanwhile, the structure of the side wall outer plate is a conventional structure generally, the hollow cavity is accommodated in the side wall outer plate as much as possible, the cross section of the hollow cavity in a limited space can be maximized through the structural design, and the structural strength of the A column can be maximized on the basis of ensuring the minimum barrier angle of the A column.

The automobile a-pillar 100 of this embodiment further includes an inner panel 5 connected to the hollow cavity 1 and used for connecting a B-pillar or a C-pillar, where the inner panel 5 includes a third curved edge 501 connected to the first curved edge 303 of the side-surrounding outer panel 3, a fourth curved edge 502 connected to the second curved edge 304, and a straight panel 503 connected to the third curved edge 501 and the fourth curved edge 502, where the straight panel 503 is adjacent to the first lower inclined panel 112 of the hollow cavity 1, and the relative positions of the straight panel 503 and the first lower inclined panel 112 are subject to actual installation requirements, and the straight panel 503 and the first lower inclined panel 112 may be in surface contact at local positions, or may have a gap at local positions, for example, when the straight panel 503 and the first lower inclined panel 112 are connected at a certain position, the connection position may have a contact between the straight panel and the first lower inclined panel 112, and other positions have. The inner plate 5 is arranged at the position connected with the B column, the third bent edge 501 of the inner plate 5 is connected with the first bent edge 303 of the side wall outer plate 3, the fourth bent edge 502 of the inner plate 5 is connected with the second bent edge 304 of the side wall outer plate 3, the connection strength of the side wall outer plate 3, the inner plate 5 and the B column can be increased, although the section area of the A column at the position can be increased at the bent edge connection part of the inner plate 5 and the side wall outer plate 3, the position is close to the position connected with the B column, and the turning sight line of a driver is not influenced. In the present embodiment, the connection between the first bead 303 and the third bead 501 is at least one of spot welding, fusion welding, and adhesion, and the connection between the second bead 304 and the fourth bead 502 is at least one of spot welding, fusion welding, and adhesion, preferably a spot welding bead; the connection between the straight plate 503 and the first lower inclined plate 112 is at least one of spot welding, fusion welding, riveting, and gluing.

In the embodiment, the length of the inner plate 5 disposed on the a-pillar 100 of the automobile is smaller than the length of the hollow cavity 1, and referring to fig. 4 and 6, the first bent edge 303 of the side-wall outer plate 3 is connected with the first upper sloping plate 111 of the hollow cavity 1 at a position away from the inner plate 5. Especially, the A column is close to the position of the vehicle head, so that the connection between the side wall outer plate 3 and the hollow cavity 1 does not need spot welding of a welding edge, the visual obstacle angle of the A column can be effectively reduced, and the turning sight of a driver is ensured.

In this embodiment, the hollow cavity 1 in the a-pillar 100 of the automobile is an internal high-pressure forming member or a roll bending member, such as hydraulic expansion forming, heating high-pressure inflation forming, and the like, and the hollow cavity of different materials (600 + 2400MPa) and required wall thickness can be prepared only by using one set of mold, especially, the hollow cavity of different wall thickness along the length direction can be prepared, so that the use requirements under different use environments can be met, and the cost can be saved. In the present embodiment, the hollow cavity 1 may be made of non-metallic materials such as steel, carbon fiber composite, or light metal materials such as aluminum alloy and titanium alloy, where the steel includes high-strength steel and ultrahigh-strength steel. When the hollow cavity is a roller bending piece, the strip is continuously bent on a roller forming machine to form a bobbin with a specified shape and size, and then the connecting ends are welded to form a closed bobbin.

The automobile A-column 100 structure of the embodiment can be widely applied to automobiles with steel automobile bodies or aluminum automobile bodies, and has the characteristics of strong applicability, wide material selection range, low comprehensive cost, good light weight effect and the like.

In the description of the present application, it is to be understood that the terms "upper", "lower", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.

Claims

1. The automobile A column is characterized by comprising a hollow cavity with a closed cross section and a structure-reinforced filler, wherein the structure-reinforced filler is arranged in the hollow cavity and is used for supporting the inner wall of the hollow cavity.

2. The automobile A-pillar according to claim 1, wherein the filling form of the structure reinforcing filler in the hollow cavity can be whole cavity filling or segmented filling; the hollow cavity is an inner high-pressure forming part or a roll bending part.

3. The a-pillar of claim 2, further comprising an injection port disposed at an upper side of the hollow cavity for injecting the structural reinforcing filler into the hollow cavity, and a first sealing part for sealing the injection port.

4. The vehicle a-pillar of claim 3 further comprising a baffle plate spaced within the hollow cavity, the baffle plate capable of partitioning the hollow cavity into filled cavities for filling with the structural reinforcing filler, one injection port for each filled cavity.

5. The A-pillar of claim 4, further comprising an exhaust port disposed on an upper side of the filling cavity and away from the injection port, and a second sealing portion for sealing the exhaust port.

6. The automotive a-pillar of any one of claims 1-5, wherein the structural reinforcing filler is a non-newtonian fluid.

7. The automotive a-pillar of any one of claims 1-3, wherein the structural reinforcing filler is a structural foam, the structural foam being polyurethane or epoxy.

8. The automotive a-pillar of claim 1, further comprising a side-wall outer panel connected to the hollow cavity, the hollow cavity comprising a first upper sloping panel, a first lower sloping panel, a second lower sloping panel, and a second upper sloping panel connected end-to-end; the side wall outer plate comprises a third upper inclined plate parallel to the second upper inclined plate, a third lower inclined plate which is connected with the third upper inclined plate and parallel to the second lower inclined plate, a first bent edge connected with the upper right end of the third upper inclined plate and a second bent edge connected with the lower right end of the third lower inclined plate; the parallel distance between the third upper inclined plate and the second upper inclined plate is 3-10mm, and the parallel distance between the third lower inclined plate and the second lower inclined plate is 3-10 mm.

9. The automotive a-pillar of claim 8, further comprising an inner panel connected to the hollow cavity and adapted to be connected to a B-pillar or a C-pillar, the inner panel including a third bead connected to the first bead of the side wall outer panel, a fourth bead connected to the second bead, and a straight panel connecting the third bead and the fourth bead, the straight panel being adjacent to the first deckle panel of the hollow cavity.

10. The automobile a-pillar of claim 9, wherein the length of the inner panel is less than the length of the hollow cavity, and the first bead of the quarter outer panel is connected to the first top sloping panel of the hollow cavity at a location remote from the inner panel.