JP2013050107A - Heat insulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high rigidity structure of a heat insulator capable of achieving thinning and weight-reduction by efficiently increasing rigidity in a required direction without causing cost increase.SOLUTION: As the heat insulator, an aluminum plate or a steel plate is press-formed so that its cross section in the width direction is curved in a chevron shape, the curved and formed surface is formed with a plurality of irregularities 3 in a trapezoidal wave shape extended along the width direction and having continuous convex parts and concave parts, the width of the convex part and the width of the concave part in the cross section in a longitudinal direction orthogonal to the width direction have the same dimension, in the plurality of irregularities 3, and the depth dimension h of the convex part and the concave part is formed smaller than a pitch dimension P, characteristically.

Description

  The present invention relates to a structure for increasing the rigidity of a heat insulator.

  For example, as shown in FIG. 11, an automotive heat insulator 101 is formed by bending an aluminum plate or a steel plate into a mountain shape, and this is mainly for the purpose of blocking heat from a catalytic converter or the like installed under the floor of the automobile. used. A bead 104 is formed on the plate surface of the heat insulator 101 so as to protrude along a mountain shape in order to increase rigidity.

  However, since the heat insulator 101 is installed in the gap between the underfloor and the catalytic converter, the shape and number of the beads 104 are insufficient to ensure the required rigidity for the heat insulator 101.

  Therefore, as shown in FIG. 12, in order to ensure sufficient rigidity without increasing the plate thickness, a metal plate on which a large number of circular convex portions 201a are formed in advance by embossing is formed by a mold having a mold gap. In addition, a heat insulator 201 and a manufacturing method thereof have been proposed (see Japanese Patent Laid-Open No. 2000-136720).

JP 2000-136720 A

  However, in the heat insulator 101 in which the beads 104 as shown in FIG. 11 are formed, in order to secure the size and number of the beads 104 in order to ensure sufficient rigidity, in order to attract the material during the molding. There is a problem that the line length of the cross section increases, resulting in an increase in the size of the material used.

  Further, in the heat insulator 201 shown in FIG. 12, since it is necessary to form the circular convex portion 201a on the metal plate in advance by embossing, there is a problem that the number of processing steps increases and cost increase cannot be avoided. Since the formation of the circular convex portion 201a by embossing is intended to increase the rigidity in all directions, in the case of a part having a different rigidity to be strengthened depending on the direction, such as a heat insulator, any direction is the same. There was also a problem that the rigidity could be increased only at a ratio and the efficiency was poor.

  The present invention has been made in view of the above problems, and the purpose of the heat insulator is to reduce the thickness and weight by efficiently increasing the rigidity in the required direction without incurring a cost increase. The object is to provide a highly rigid structure.

  In order to achieve the above object, the heat insulator according to claim 1 is a trapezoid in which a cross section in the width direction extends along the width direction on a surface formed in a chevron shape, and a convex portion and a concave portion are continuous. A plurality of corrugated irregularities are formed, and the plurality of irregularities have the same width of the convex portion and the width of the concave portion in the cross section in the length direction perpendicular to the width direction, and the convex portion and the concave portion The depth dimension is smaller than the pitch dimension.

  The heat insulator according to claim 2 is provided with a mounting boss having a smooth seating surface on the surface curved and formed in the chevron shape, and the pitch dimension of the plurality of irregularities is larger than the seating surface dimension of the mounting boss. It is small.

  Furthermore, the heat insulator according to claim 3 is provided with a bead having a smooth surface and protruding outward in a radial direction on a surface curved and formed in the chevron shape, and the pitch dimension of the plurality of irregularities Is smaller than the width dimension in the direction perpendicular to the extending length direction of the bead.

  Therefore, according to the first aspect of the present invention, the rigidity in the width direction of the heat insulator can be efficiently increased, and the heat insulator can be reduced in thickness and weight.

  According to the second aspect of the present invention, since the seating surface of the mounting boss is formed smoothly, the rigidity in the length direction of the heat insulator can be increased similarly to the bead. Moreover, since the pitch dimension of the unevenness is smaller than the seating surface dimension of the mounting boss, the rigidity in the width direction of the heat insulator on the curved surface adjacent to the mounting boss can be increased. That is, the rigidity can be increased even when the shape and number of beads cannot be sufficiently ensured due to restrictions such as mounting space.

  As is apparent from the above description, according to the present invention, when corrugated irregularities are formed on a press-molded product, the rigidity in the direction in which the irregularities of the press-molded product extend is increased, so there is no cost increase. The rigidity in the required direction can be increased efficiently, and the effect of reducing the thickness and weight of the press-formed product can be obtained.

  Moreover, according to this invention, the effect that the rigidity of a press molded product can be improved over a some direction by combining an unevenness | corrugation and a bead is acquired.

  Furthermore, by forming the seating surface of the mounting boss smoothly, the rigidity in the length direction of the heat insulator can be increased similarly to the bead. Further, by forming the uneven pitch dimension smaller than the seating surface dimension of the mounting boss, the rigidity in the width direction of the heat insulator on the curved surface adjacent to the mounting boss can be increased.

It is a perspective view of the heat insulator for motor vehicles provided with the highly rigid structure concerning this invention. It is a side view of the heat insulator for motor vehicles provided with the highly rigid structure concerning the present invention. It is a top view of the heat insulator for motor vehicles provided with the highly rigid structure concerning this invention. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is an expanded sectional view which shows the cross-sectional shape of a corrugated shape. It is a figure which shows the orthogonal | vertical direction (X, Y direction) rigidity value of the flat plate which has an emboss shape and a waveform shape. It is a figure which shows the orthogonal | vertical direction (X, Y direction) rigidity value of the insulator which has a flat plate, an emboss shape, and a wave shape. It is a fragmentary perspective view of the heat insulator which shows the example of a combination of corrugated unevenness and a bead. It is a perspective view which shows the example of application to the floor heat insulator of this invention. It is a perspective view which shows the example of application to the silencer insulator of this invention. It is a perspective view of the heat insulator which concerns on the prior art example 1. FIG. It is a perspective view of the heat insulator which concerns on the prior art example 2. FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 is a perspective view of a heat insulator for an automobile having a highly rigid structure according to the present invention, FIG. 2 is a side view of the heat insulator, FIG. 3 is a plan view of the heat insulator, and FIG. 4 is a line AA in FIG. Sectional drawing and FIG. 5 are enlarged sectional views showing the sectional shape of corrugated irregularities.

  As shown in FIG. 1, an automotive heat insulator (heat shield plate) 1 according to the present embodiment covers a catalytic converter 2 installed under the floor of an automobile from above, and heat (catalyst and catalyst) from the catalytic converter 2 is covered. The transmission of heat (reaction heat with exhaust gas) to the vehicle body is interrupted, and this is obtained by press forming a steel plate or an aluminum plate. In other words, the heat insulator 1 is bent into a mountain shape (substantially arcuate in cross section) along the outer shape of the cylindrical catalytic converter 2, and both edges 1a in the width direction (Y direction in the drawing) are curled in a U shape. Molded (see FIG. 4).

  In addition, mounting bosses 1b are integrally projected at three positions, both ends and an intermediate portion in the length direction (X direction in the drawing) of the upper surface of the heat insulator 1, and bolt insertion holes are provided at the center of each mounting boss 1b. 1c is perforated. The mounting boss 1b has a seating surface that is smooth and is formed across a plurality of steps of unevenness 3 to be described later.

  Thus, in the heat insulator 1 according to the present embodiment, a large number of irregularities 3 having a corrugated shape are integrally formed over the entire width direction (Y direction in the drawing) along the mountain shape, A plurality of beads 4 having a predetermined width are formed along the width direction.

  By the way, the gap between the catalytic converter 2 where the heat insulator 1 is installed and the under floor of the automobile is narrow, and it is difficult to satisfy the rigidity required for the heat insulator 1 with the shape and number of the beads 4.

  Therefore, in the present embodiment, a necessary number of the irregularities 3 having a corrugated shape having a small size (height, width, pitch, etc.) with respect to the shape of the bead 4 are formed in a direction satisfying the required rigidity. I tried to do it.

  The heat insulator 1 having the above configuration is integrally formed by press forming of a steel plate or an aluminum plate, but the dimensions of the corrugations 3 forming the corrugated shape formed on the heat insulator 1 can be formed without drawing materials. It is set to a valid value. Therefore, it is not necessary to add a new process to the forming process of the corrugations 3 having a corrugated shape, and the unevenness 3 can be formed within the existing process (for example, simultaneous processing with the forming of the beads 4). Therefore, it is possible to avoid an increase in cost due to an increase in the number of processes and a change in material dimensions.

  Here, FIG. 5 shows the details of the cross-sectional shape of the corrugations 3 forming a corrugated shape. As shown in FIG. 5, the pitch of the corrugations 3 is P, the height is h, and the elongation of the material is δ (%). Then, in order to be able to perform overmolding without attracting materials, the following formula needs to be satisfied among P, h, and δ.

h ≦ P (δ (δ + 100)) 1/2 / 200 (1)
Therefore, when the material is iron and the elongation is δ = 30%, from the equation (1),
h ≦ 0.312P (2)
Need to be satisfied.

Further, when the material is aluminum (3000 series, 5000 series, 6000 series) and the elongation is 18%, from the formula (1),
h ≦ 0.230P (3)
Need to be satisfied.

  Thus, the heat insulator 1 integrally formed by press forming of a steel plate or an aluminum plate is attached to the lower surface of the vehicle body by a bolt (not shown) inserted from below into a bolt insertion hole 1c formed in the mounting boss 1b. As described above, the catalytic converter 2 is covered from above and functions to block the transfer of heat from the catalytic converter 2 to the vehicle body.

  By the way, the rigidity of a product is generally expressed by the following equation.

I × E (4)
Where I: secondary moment of inertia (value determined by product shape)
E: Young's modulus (coefficient determined by material properties)
Conventionally employed beads to increase the rigidity of a product aim to increase the value of the moment of inertia by changing the shape of the product.

  On the other hand, a convex portion by embossing (hereinafter referred to as “embossed shape”) and a corrugated unevenness according to the present invention (hereinafter referred to as “corrugated shape”) are sufficiently smaller than the bead. When set, since the effect of increasing the rigidity can be obtained without greatly changing the shape of the product, it can be considered that the value of the Young's modulus E is artificially increased.

Therefore, when the shape and number of beads cannot be secured sufficiently due to restrictions such as mounting space, and when it is desired to avoid an increase in the plate thickness of the material, which increases costs, the embossed shape and the corrugated shape according to the present invention are rigid. This is an effective way to increase

  However, there is a great difference in the directionality of the stiffness value between the embossed shape and the corrugated shape. Here, the rigidity values in the two orthogonal directions (X and Y directions) for the embossed shape and the corrugated shape with respect to the metal flat plate are shown in FIGS. 6A and 6B, where the rigidity value of the flat plate is 1. FIG.

  As shown in FIG. 6A, in the embossed shape, the stiffness value does not indicate directionality, and shows the same value (1.6) over all directions. The rigidity value is represented by the ratio of the flat plate as 1. On the other hand, in the corrugated shape, as shown in FIG. 6B, the rigidity value is very high (12) in the direction parallel to the wave (Y direction), but the direction orthogonal to the direction (X (Direction) shows a low stiffness value (0.85).

  Therefore, many chevron shapes are adopted as the shape of the heat insulator, and the rigidity value of the heat insulator having such a shape varies greatly depending on the direction.

  Here, the rigidity values in two orthogonal directions (X and Y directions) of the heat insulator as a flat plate, the heat insulator having an embossed shape, and the heat insulator having a corrugated shape are set to 1 as the rigidity value of the flat plate as shown in FIG. They are shown in a), (b), and (c), respectively.

  In the flat plate heat insulator shown in FIG. 7A, the rigidity value in the length direction (X direction) shows a high value (104), while the rigidity value in the width direction (Y direction) shows a very low value (2 ).

  In the heat insulator having the embossed shape shown in FIG. 7B, the rigidity values in the length direction (X direction) and the width direction (Y direction) are the rigidity values of the flat plate heat insulator shown in FIG. The stiffness value in the length direction (X direction) shows a high value (166), whereas the stiffness value in the width direction (Y direction) shows a very low value (3). In the same manner as the flat plate heat insulator shown in FIG.

  On the other hand, in the heat insulator according to the present invention having the corrugated shape shown in FIG. 7C, the rate of increase in the rigidity value in the width direction (Y direction) is increased to show a high value (25), The rigidity value in the length direction (X direction) is lower than that of the flat plate heat insulator shown in FIG. 7A and the heat insulator having the embossed shape shown in FIG. 7B (104, 166) (88). ).

  Thus, in the heat insulator 1 according to the present embodiment, the corrugated irregularities 3 are integrally formed by press molding along the width direction (Y direction), which has conventionally been low in rigidity, leading to an increase in cost. Therefore, the rigidity in the width direction (Y direction) can be efficiently increased, and the weight of the heat insulator 1 can be reduced by reducing the thickness of the steel plate or aluminum plate as the material by the amount of the increased rigidity. Specifically, the thickness of the steel plate or aluminum plate, which is a material, was conventionally required to be 0.5 mm, but in this embodiment, the plate thickness could be reduced to 0.35 to 0.4 mm. .

  In the present embodiment, the pitch P and the height h of the corrugated irregularities 3 are set so as to satisfy the formula (2) or the formula (3). Therefore, the heat insulator 1 is formed by overhang molding without calling in the material. The corrugated irregularities 3 can be formed. Further, since it is not necessary to add a processing step such as embossing as in the prior art, an increase in material can be prevented, and cost reduction and weight reduction can be achieved. Furthermore, since P> h is satisfied by satisfying the expressions (2) and (3), the rigidity in the width direction of the heat insulator can be increased efficiently, and the heat insulator can be made thinner and lighter. Can do.

  In addition, as shown in FIG. 8, if a bead 5 having a predetermined width is formed in the length direction on the top of the heat insulator 1 in which a large number of corrugated irregularities 3 are formed along the width direction, Thus, the rigidity in the length direction can be increased. Also, the rigidity can be increased by using corrugated irregularities 3 instead of the beads 5.

  Here, a form in which the present invention is applied to a floor heat insulator 11 for an automobile is shown in FIG. 9, and a form in which the present invention is applied to a silencer insulator 21 is shown in FIG. 10, but when applying the present invention, these floor heat insulators 11 are applied. In addition, the strength analysis of the silencer insulator 21 is performed in advance, the plate surface and the direction that need to be increased in rigidity are identified, and the corrugated irregularities 3 are formed along that direction.

  In the above embodiment, the present invention has been described with reference to an embodiment in which the present invention is applied particularly to an automotive press-molded product such as a heat insulator. However, the present invention can be applied to any other press-formed product as well. Of course.

1 Heat insulator (press-molded product)
1a Width direction edge 1b of heat insulator 1b Mounting boss 1c Bolt insertion hole 2 Catalytic converter 3 Concavity and convexity 4 and 5 Bead 11 Floor heat insulator (press-molded product)
21 Silencer insulator (press-molded product)

Claims (3)

An aluminum plate or a steel plate is a heat insulator formed by bending the cross section in the width direction into a chevron shape,
A plurality of irregularities having a trapezoidal corrugated shape extending along the width direction and having convex portions and concave portions continuous are formed on the curved surface.
The plurality of concaves and convexes are formed such that the width of the convex part and the width of the concave part in the cross section in the length direction perpendicular to the width direction are the same dimension, and the depth dimension of the convex part and the concave part is smaller than the pitch dimension. A heat insulator characterized by that. The surface formed curved in the chevron shape includes a mounting boss with a smooth seating surface,
The heat insulator according to claim 1, wherein the pitch dimension of the plurality of irregularities is smaller than a seating surface dimension of the mounting boss. The surface curved and formed in the chevron shape includes a bead extending and projecting toward the outside in the radial direction with a smooth surface,
3. The heat insulator according to claim 1, wherein the pitch dimension of the plurality of irregularities is smaller than a width dimension in a direction orthogonal to the extending length direction of the bead.

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