JP6791294B2 - Vehicle roof structure and its design method - Google Patents

Description

The present invention relates to a vehicle roof structure and a design method thereof, and relates to a technique for improving the snow cover strength of a roof panel.

Automobile panels are outer panel parts called roof panels and inner panel parts such as floors and dash lowers, and are a group of parts with a wide projected area. Therefore, the ratio of weight reduction by reducing the plate thickness is much larger than that of other skeletal parts. Among them, the roof panel has a large projected area, especially in vans and minivans, so the effect of reducing the weight of the vehicle body by thinning the plate is great. In addition, there is a tendency for the center of gravity of the vehicle body to be lowered due to the desire for excellent maneuverability and enjoyment of driving, so there is a particularly strong need for weight reduction of the roof.
Here, the maximum required performance of the roof is the snow strength performance. The snow strength is the strength required to prevent snow from accumulating on the roof when traveling outdoors or parking and stopping, causing the roof panel to invert and permanently deform (the panel cannot be restored) due to the weight of the snow. That is. Therefore, the snow strength performance is a special performance required only for the parts constituting the roof. Since the strength here is related to the inversion (buckling) of the panel, it can be considered as a kind of rigidity.

Here, in Patent Document 1, a thermosetting reinforcing sheet having adhesiveness is attached to the entire back surface of the panel, and the reinforcing sheet is foam-cured at the time of painting and baking on the panel surface to simultaneously perform sound absorption and panel reinforcement. Are listed.
Further, Patent Document 2 describes that, as a method of reinforcing against snow cover on the roof, a roof rail outer is assembled in advance on a roof panel to produce a roof component, and the roof component is attached to a roof rail inner on the cab side.

Japanese Unexamined Patent Publication No. 9-104365 Japanese Unexamined Patent Publication No. 4-63773

In order to improve the snow cover strength while thinning the roof panel in order to reduce the weight of the vehicle body, it is effective to increase the cross-sectional coefficient of the roof panel from the viewpoint of increasing the rigidity to the distributed load due to the snow cover. As the method, for example, a bead shape may be arranged. However, forming a bead on the roof panel may be avoided for reasons such as causing a muffled sound in the car or improving the appearance. It is also effective to reduce the radius of curvature of the roof, but from the design balance of the car, the roof is required to have a shape that does not protrude (the radius of curvature is large).
Furthermore, it is possible to improve the rigidity by increasing the reinforcement, but on the contrary, it leads to an increase in mass, so we want to minimize the number of reinforcements.
Due to these conflicting needs and performance requirements, it is difficult to thin the roof panel.

Here, in Patent Document 1, no consideration is given to partial deflection due to snow accumulation peculiar to the roof, and since a thermosetting type reinforcing sheet is provided on almost the entire surface of the panel, it leads to high cost and the larger the panel area, the more snow accumulation occurs. There is a problem that the effect is reduced due to the partial deflection caused by.
Further, the technique described in Patent Document 2 seems to be effective for a roof having a narrow area where rigidity can be easily secured, but its performance is reduced in a roof having a large area such as a van or a minivan because the rigidity in the longitudinal direction of the vehicle decreases. There is little effect in securing.
Further, for a one-point load such as tension rigidity, it is possible to take measures by reinforcing the weak point. However, it is difficult to narrow down the reinforcement points because the snow cover is the distributed load on the entire panel surface.

The present invention has been made by paying attention to the above points, and an object of the present invention is to effectively secure the snow cover strength without increasing the mass of parts in the roof structure.

In order to solve the problem, one aspect of the present invention is a vehicle roof structure including a roof panel and a plurality of reinforcements that support the roof panel from below, and on the lower surface of the roof panel. One or two or more reinforcing sheets having a resin layer are partially arranged, and each reinforcing sheet is interposed between one of the plurality of reinforcements and the roof panel. The gist is that it is supported by only one of the above-mentioned plurality of reinforcements.

Further, one aspect of the present invention includes a roof panel, a plurality of reinforcements that support the roof panel from below, and a reinforcing sheet arranged under the roof panel, and the reinforcing sheet is made of resin. It has a layer, and one or more of the reinforcing sheets are partially arranged on the lower surface of the roof panel, and each reinforcing sheet is supported or supported only by one of the plurality of reinforcements. Under the condition that the roof panel is not supported by the reinforcement, the deflection distribution of the roof panel when a snow load is applied from above to the roof panel supported by the plurality of reinforcements is obtained, and based on the deflection distribution, the deflection distribution is obtained. The gist is that the position where the reinforcing sheet is provided is a position where the deflection due to the snow load is small and the distribution of the deflection is estimated to be uniform.

According to the aspect of the present invention, by appropriately arranging the reinforcing sheet having a resin layer partially between the roof panel and the reinforcement, the snow cover strength is not increased without increasing the mass and the number of parts of the roof structure. Can be improved. As a result, according to the aspect of the present invention, it is possible to reduce the weight by further thinning the roof panel.

It is a figure which shows the roof panel. It is a top view which shows the arrangement of a reinforcement. It is a figure which shows the cross section of a reinforcement. It is a top view which shows the relationship with the mastic adhesive of Reinforce. It is a figure which shows the example of the deflection distribution. It is a figure which shows the arrangement example of the reinforcing sheet. FIG. 6 is a cross-sectional view taken along the line AA'of FIG. 6 showing an example of a roof panel, reinforcement and reinforcing sheet. It is sectional drawing explaining the reinforcement sheet. It is a figure which shows the model of an Example. It is a figure which shows the evaluation result.

Next, an embodiment of the present invention will be described with reference to the drawings.
Here, the drawings are schematic, and the relationship between the thickness and the plane dimension, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention has the following shapes, structures, etc. of components. Not specific. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.
In addition, the dimensions in the examples are also shown in each figure. The unit is all [mm].

The vehicle roof structure of the present embodiment includes a roof panel and a plurality of reinforcements that support the roof panel from below.
As shown in FIG. 1, the roof panel 1 has a surface shape in which the upper surface (surface) has an upwardly convex radius of curvature.
The plurality of reinforcements 2 are arranged on the back surface side of the roof panel 1 so as to be lined up along the back surface. Specifically, as shown in FIG. 2, a plurality of reinforcements 2 of the present embodiment are arranged along the longitudinal direction of the roof panel 1.

The reinforcement 2 has a hat-shaped cross-sectional shape as shown in FIG. 3, for example, and is composed of a central portion 2a and left and right mounting surface portions 2b located on both sides of the central portion 2a in the width direction.
Then, as shown in FIG. 4, the reinforcement 2 was attached to the back surface (lower surface) of the roof panel 1 with a mastic adhesive 3 arranged at predetermined intervals in the longitudinal direction with respect to the left and right attachment surface portions 2b. It has a structure.
Further, the longitudinal end portion of the reinforcement 2 is fixed to a vehicle body frame (not shown).
The roof panel 1 and the reinforcement 2 are not limited to the above structure, and a known vehicle roof structure may be adopted.

For the above roof structure, the deflection distribution of the panel when a snow load (equally distributed load) is applied to the roof panel 1 from above is obtained. The deflection distribution may be obtained by an experiment or by calculating a displacement contour diagram by CAE or other structural analysis using a computer.
Next, from the obtained deflection distribution, the first portion T1 that is the most flexible, that is, the most flexible portion, and the second portion T2, which is the second most flexible portion, that is, the second flexible portion, are specified. ..
The identification of the first portion T1 and the second portion T2 may also be specified by an automatic calculation by a computer.

In the case of the present embodiment, it is assumed that the central portion in the longitudinal direction is structurally easy to bend, and the CAE analysis shows that the deflection is maximized at the positions of reference numerals T1 and T2 in FIG. That is, T1 and T2 are the most flexible portion and the second most flexible portion. Further, in FIG. 5, T3 is a portion where the deflection is small.
In the present embodiment, the reinforcing sheet 4 is arranged so as to be supported by the reinforcement 2 located between the two maximum deflection portions T1 and T2 in FIG. 5 (arranged at the position of reference numeral R in FIG. 5). In particular, since the deflection is large on the central portion side in the longitudinal direction of the reinforcement 2, the reinforcing sheet 4 is arranged at the central portion in the longitudinal direction of the reinforcement 2.

That is, as shown in FIG. 6 and FIG. 7 which is a cross-sectional view taken along the line AA, one reinforcing sheet 4 is interposed between the back surface of the roof panel 1 and the reinforcement 2 located at the center in the longitudinal direction. Let me. In this example, the reinforcing sheet 4 is attached to the back surface of the roof panel 1, and the mastic adhesive 3 is interposed in the gap between the lower surface of the reinforcing sheet 4 and the reinforcement 2. If no gap is formed, it is not necessary to interpose the mastic adhesive 3.
Here, the size of the reinforcing sheet 4 is not limited, but is set to a size that overlaps with only one reinforcement 2 in a plan view. However, although the reinforcing sheet 4 is lightweight, it is naturally preferable that the reinforcing sheet 4 has a small area from the viewpoint of reducing the weight of the vehicle body in consideration of the mass of the reinforcing sheet 4 itself. If the reinforcing sheet 4 has a rectangular shape and a size of up to 300 mm × 600 mm, the mass increase can be suppressed to be smaller than that of increasing the reinforcement 2.

Further, it is preferable that the reinforcing sheet 4 has a rectangular shape and a size of 100 mm × 200 mm or more.
Further, one reinforcing sheet 4 is most effective. This is because by attaching it between two parts with large deflection, it is possible to suppress the deflection growth on both sides and eliminate the trigger for panel reversal under snow load. This also brings the deflection distribution of the entire surface closer to uniform.
When increasing the number of the reinforcing sheets 4, for example, when the reinforcing sheet 4 is attached between a portion having a small deflection and a portion having a large deflection, the growth of the deflection is biased, and a new reversal point may be generated.

The reinforcing sheet 4 that reinforces from the back surface (lower surface) of the roof panel 1 has a resin layer. The reinforcing sheet 4 may be composed of only the resin layer, or as shown in FIG. 8, another layer may be laminated in addition to the resin layer 4a.
The reinforcing sheet 4 illustrated in FIG. 8 includes a resin layer 4a and an adhesive layer 4b provided on the surface (upper surface) of the resin layer 4a. The reinforcing sheet 4 illustrated in FIG. 8 further has a restraining layer 4c for the purpose of suppressing deformation of the resin layer 4a. The restraint layer 4c may be provided between the resin layer 4a and the adhesive layer 4b. It is preferable to have the restraint layer 4c, but it is not necessary to have the restraint layer 4c.

The resin constituting the resin layer 4a is preferably a curable resin. As the curable resin, a photocurable resin and a thermosetting resin can be considered, but a thermosetting resin is usually used.
When the resin layer 4a is composed of a thermosetting resin, the resin layer 4a is composed of a thermosetting resin such as an epoxy resin containing a foaming agent. It is not necessary to contain a foaming agent, but when a foaming agent is contained, the foaming agent foams due to heating when the surface of the roof panel 1 is baked and painted, and the layer thickness increases. The gap can be eliminated more effectively, and the resin can be cured by air cooling after baking and painting.
The restraining layer 4c may be made of, for example, carbon fiber, glass fiber, non-woven fabric, metal foil, or the like.
The adhesive layer 4b is not particularly limited as long as it has the same function as the adhesive layer of the seal, is applied by adhering to the roof panel, and has a performance of not peeling even after heating the coating.

Here, since the panel rigidity of the portion is locally increased by attaching the reinforcing sheet 4, structural analysis may be performed under that condition to specify the location where the reinforcing sheet 4 is arranged. However, as described above, arranging one or two reinforcing sheets 4 at positions close to the two places where the deflection is large is convenient and suppresses the increase in mass, and effectively improves the snow cover strength. It can be expressed.
It should be noted that the snow cover strength is improved even if the reinforcing sheet 4 is attached to the two positions where the deflection is maximum, without being supported by the reinforcement 2, as in the example PP3 described later. The reinforcing sheet 4 may be partially attached in this way.

That is, a plurality of reinforcing sheets 4 are partially arranged on the lower surface of the roof panel 1, and each reinforcing sheet 4 is supported only by one of the plurality of reinforcements 2. Alternatively, the analysis condition is a condition that is not supported by the reinforcement 2. Preferably, the analysis condition is a condition in which only one of the plurality of reinforcements 2 is supported by the reinforcement 2. Then, the deflection distribution of the roof panel 1 when a snow load is applied from above to the roof panel 1 supported by the plurality of reinforcements 2 is obtained, and the reinforcing sheet 4 is provided based on the deflection distribution. The position where the reinforcing sheet 4 is provided may be set at a position where the deflection due to the snow load is small and the distribution of the deflection is estimated to be uniform. The number of the reinforcing sheets 4 is preferably one or two.

However, it is preferable that the reinforcing sheet 4 is supported by the reinforcement 2 because the mounting strength against vehicle body vibration is high.
Here, the snow cover strength is evaluated by a load value at which the panel buckling occurs when the load increases with an evenly distributed load applied to the entire panel of the roof panel 1. It is evaluated that the higher the buckling generated load, the superior the performance, that is, the panel is less likely to reverse even if the snowfall increases.

In addition, although there is tension rigidity as a similar performance, this is the panel rigidity when a load is applied to a certain point, so it is sufficient to take measures only for that part. However, the snow strength is different because it is the performance against the distributed load applied to the entire panel.
Then, in the present embodiment, a portion where the panel is greatly deflected when a snow load is applied is found, and the reinforcing sheet 4 is arranged at a position between the maximum portion and the second largest portion and in a range overlapping with the reinforcement 2. , It is possible to effectively improve the snow cover strength while suppressing the mass increase.

As described above, in the present embodiment, the mass of the parts is increased by appropriately partially arranging the reinforcing sheet 4 having the lightweight and highly rigid resin layer 4a on the back surface of the panel without being influenced by the design of the car. It is possible to effectively secure the snow cover strength for the roof structure without causing it.
That is, according to the present embodiment, by arranging the reinforcing sheet 4 partially having the resin layer 4a between the roof panel 1 and the reinforcement 2, the mass of the roof structure and the number of parts are not increased. , The snow strength can be improved. As a result, according to the present embodiment, it is possible to reduce the weight by further thinning the roof panel 1.

A CAE model having a size of 1500 W × 2500 L mm is set by projection, simulating the roof component shown in FIG. As shown in FIG. 1, the shape of the roof panel 1 is a simple shape having curvatures in two directions, R5000 mm in the W direction and R20000 mm in the L direction. The plate thickness of the panel was 0.60 mm.
Further, on the back surface of the roof panel 1, five hat-shaped reinforcements 2 were arranged at equal intervals, imitating actual parts (see FIG. 2). As shown in FIGS. 3 and 4, the cross-sectional shape of the reinforcement 2 is a hat type and has the same total length.

Here, as shown in FIG. 7, which is a cross section of AA'in FIG. 6, the mastic adhesive 3 arranged between the roof panel 1 and the reinforcement 2 reflects the elastic behavior of the mastic adhesive 3. A mastic adhesive 3 was set between the flange of the reinforcement 2 and the reinforcing sheet 4 as a beam element having a Young's modulus.
Further, the reinforcing sheet 4 was modeled as shown in FIG. The reinforcing sheet 4 was arranged between the roof panel 1 and the mastic adhesive 3, and the mastic adhesive 3 side was composed of a shell element and the roof panel 1 side was composed of a beam element. In this example, it is set as a condition of the reinforcing sheet that the reinforcing sheet 4 is composed of only a resin layer and the resin layer is made of a thermosetting resin.
First, when a snow load is applied with the model of FIG. 6, the maximum part of deflection can be found. That is, in this example, as shown in FIG. 5, both sides of the reinforcement 2 in the central portion are the maximum deflection portions T1 and T2.

Then, a study implementation model as shown in FIG. 9 was created.
"No PP" is a model without the reinforcing sheet 4.
The "PP1" is a model in which one reinforcing sheet 4 is supported by a central reinforcement 2 located between two maximum deflection portions.
The "PP2" is a model in which two reinforcing sheets 4 are arranged in addition to the maximum deflection portion with respect to the "PP1".
"PP3" is a model in which the reinforcement 2 is not provided and is arranged in the maximum deflection portion.

The above four study implementation models were evaluated.
The evaluation was performed by snow load analysis. As the load, an evenly distributed load was applied downward in parallel with the vehicle height direction over the entire surface of the roof panel 1.
Then, it was evaluated by the curve of the displacement and the load in the maximum deflection portion after the roof panel 1 was inverted. The superiority or inferiority of the snow strength was evaluated by the height of the load (buckling load) in which the panel displacement suddenly increased.
The result is shown in FIG.

As can be seen from FIG. 10, it can be seen that when only one reinforcing sheet 4 is arranged in the two maximum deflection portions, the reversal load is the highest and the snow strength performance is the best.
It can be seen that PP2 and PP3 have almost the same snow strength performance, but PP1 is superior, and it is preferable that the number of reinforcing sheets 4 is small. In the case of PP2, the portion where the deflection is not large is also reinforced by the reinforcing sheet 4, and the distribution of rigidity is slightly worse than that of PP1.
However, in either case, the snow strength is improved by attaching the reinforcing sheet 4, so that it is preferable to improve the snow strength performance with a small number of sheets in consideration of weight reduction. That is, it is preferable to obtain an appropriate arrangement position with two or less, preferably one reinforcing sheet 4.

1 Roof panel 2 Reinforce 3 Mastic adhesive 4 Reinforcing sheet 4a Resin layer 4b Adhesive layer 4c Restraint layers T1, T2 Maximum deflection

Claims (6)

A vehicle roof structure including a roof panel and a plurality of reinforcements that support the roof panel from below.
Each of the plurality of reinforcements is attached to the underside of the roof panel with a mastic adhesive.
One or two or more reinforcing sheets having a resin layer are partially arranged on the lower surface of the roof panel, and the reinforcing sheet is adhered to the lower surface of the roof panel.
Each reinforcing sheet is interposed between the reinforcement of one of the plurality of reinforcements and the roof panel, and is supported only by the reinforcement of one of the plurality of reinforcements. The characteristic roof structure for vehicles. The vehicle roof structure according to claim 1, wherein the resin constituting the resin layer is a curable resin. When viewed from above, the reinforcing sheet is interposed only between the reinforcement and the roof panel, which are closest to both the first location where the roof panel is most flexible due to the snow load and the second location where the roof panel is second most flexible. The vehicle roof structure according to claim 1 or 2, wherein the roof structure is provided. A roof panel, a plurality of reinforcements that support the roof panel from below, and a reinforcing sheet arranged under the roof panel are provided.
Each of the plurality of reinforcements is attached to the underside of the roof panel with a mastic adhesive.
The reinforcing sheet has a resin layer, and one or two or more of the reinforcing sheets are partially arranged on the lower surface of the roof panel, and the reinforcing sheet is adhered to the lower surface of the roof panel to reinforce each. The seat is loaded with a snow load from above on the roof panel supported by the plurality of reinforcements under the condition that the seat is supported by only one of the plurality of reinforcements or is not supported by the reinforcements. Obtaining the deflection distribution of the roof panel at the time of
A vehicle roof characterized in that, based on the above-mentioned deflection distribution, the above-mentioned reinforcing sheet is provided at a position where the above-mentioned deflection due to the snow load is small and the distribution of the deflection is estimated to be uniform. How to design the structure. The method for designing a roof structure for a vehicle according to claim 4, wherein the resin constituting the resin layer is a curable resin. Claim 4 or claim, wherein the reinforcing sheet is used as one sheet, and the location where the reinforcing sheet is provided is determined on the condition that the reinforcing sheet is supported by only one of the plurality of reinforcements. Item 5. The method for designing a roof structure for a vehicle according to item 5.

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