Protector

Abstract

To provide a fuel tank cover having sufficient heat insulating performance while reducing costs by reducing the amount of insulator used. [Solution] A fuel tank cover (1) comprising an insulator (2) made of foam and formed into a bowl shape along the outer surface (7b) of the underside of the fuel tank, and a protector (3) molded from resin into a bowl shape and covering the outer surface of the insulator, further comprising a plurality of first ribs (4) formed in a raised manner on the inner surface of the bottom wall of the protector (3) that faces the lower outer surface (71) of the fuel tank, via the insulator (2).When the protector (3) is assembled to the vehicle body, with the insulator (2) placed within the bowl and covering the fuel tank (7), the bottom underside (21b) of the insulator (2) is received by the first ribs (4), and a first space (S1) is formed between the bottom underside (21b) of the insulator (2) and the inner surface of the bottom wall of the protector (3).

Description

Technical Field

[0001] The present invention relates to a fuel tank cover that covers a fuel tank installed in a vehicle body such as an automobile.

Background Art

[0002] Vehicles such as automobiles are provided with fuel tanks, and these fuel tanks are usually attached to the vehicle body panels under the rear seats or in the trunk room. Therefore, in summer, due to the radiant heat reflected from the ground, the fuel in the fuel tank may increase in temperature. To avoid this, several inventions have been proposed that cover the fuel tank with a fuel tank cover having high heat insulation properties.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 states in its claim 1 that "a tank protector characterized in that a resin layer and a metal layer are formed in a multilayer structure laminated in two or more layers in the thickness direction." Further, in claim 2, it states that "the tank protector according to claim 1, wherein a gap is formed between the resin layer and the metal layer." However, the heat insulation effect due to the formation of the gap cannot be increased much. In paragraph 0023 of Patent Document 1, it states that "this gap may not communicate... However, in order to perform drainage well, it is preferable that the gap communicates with the outside of the tank protector." Also, the content in the embodiment is that the gap communicates with the outside of the tank protector. In a structure where air flows into the gap and there is movement in the air within the gap, there is a problem of a decrease in the heat insulation effect. Patent Document 2 is a fuel tank cover composed of an insulator (referred to as a protector in Patent Document 2) formed in a bowl shape along the outer surface of the lower side of the fuel tank and a protector (referred to as an under cover in Patent Document 2) formed in a bowl shape along the outer surface of the insulator. However, since the entire region where the insulator is accommodated is filled with a foam insulator, the cost is high.

[0005] The present invention aims to solve the above problems and provide a fuel tank cover with sufficient heat insulation performance while reducing the amount of insulator used to reduce costs.

Means for Solving the Problems

[0006] To achieve the above object, the gist of the first invention is a fuel tank cover comprising an insulator made of a foam formed in a bowl shape along the outer surface of the lower side of the fuel tank, and a protector resin-molded in a bowl shape to cover the outer surface of the insulator, wherein the protector further comprises a plurality of first ribs formed in a raised manner on the inner surface of the bottom wall of the protector facing the lower outer surface of the fuel tank via the insulator, and the protector houses the insulator in its bowl, covers the fuel tank and is assembled to the vehicle body, whereby the lower bottom surface of the insulator is received by the first ribs, and a first space is formed between the lower bottom surface of the insulator and the inner surface of the bottom wall of the protector. The fuel tank cover of the second invention is characterized in that, in the first invention, the foam of the insulator is a closed-cell foam plastic formed of an olefin-based synthetic resin or a composite material thereof. The fuel tank cover of the third invention is characterized in that, in the first or second invention, the insulator is a soft foam, the first ribs bite into the lower bottom surface of the insulator and the insulator is received by the first ribs, and the first space is formed between the lower bottom surface of the insulator and the inner surface of the protector. The fuel tank cover of the fourth invention is characterized in that, in the third invention, along with the assembly of the protector housing the insulator to the vehicle body, the side portion of the insulator made of a soft foam is provided so as to interfere with the outer surface of the side portion of the fuel tank, and in this assembly, the side portion of the insulator is elastically compressed and deformed under the pressure of the fuel tank. The fuel tank cover of the fifth invention is characterized in that, in the first to third inventions, the protector further comprises second ribs formed in a raised manner on the inner surface of the side wall of the protector facing the outer surface of the side portion of the fuel tank, and the protector houses the insulator in its bowl, covers the fuel tank and is assembled to the vehicle body, whereby the outer surface of the side portion of the insulator is received by the second ribs, and a second space is formed between the outer surface of the side portion of the insulator and the inner surface of the side wall of the protector.In the fuel tank cover of the sixth invention, in the first to fifth inventions, an annular outer flange that projects horizontally outward from the outer peripheral edge of the bowl-shaped portion related to the protector is formed, and a third rib that runs in the circumferential direction of the outer flange is formed on the upper surface side of the outer flange. On the other hand, the insulator housed in the protector has a peripheral edge portion that is placed on the third rib beyond the outer peripheral edge of the protector. The protector houses the insulator in its bowl and is assembled to the vehicle body by covering the fuel tank, so that the lower surface of the peripheral edge portion of the insulator is received by the third rib.

Advantages of the Invention

[0007] The fuel tank cover of the present invention forms a space of an air layer with low thermal conductivity by the raised structures of the first rib and the second rib provided on the inner surface of the protector, so that even if the thickness of the insulator is reduced, a sufficient heat insulation effect can be obtained, and excellent effects such as cost reduction and weight reduction are exhibited.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the fuel tank cover according to the present invention will be described in detail. FIGS. 1 to 9 show one form of the fuel tank cover of the present invention. FIG. 1 is an exploded perspective view thereof, FIG. 2 is a cross-sectional view of FIG. 1, FIG. 3 is a cross-sectional view of the fuel tank covered with the fuel tank cover and assembled to the vehicle body, FIG. 4 is a partially enlarged view of FIG. 3, FIG. 5 is a perspective view of a protector in another aspect, FIG. 6 is a perspective view of a protector in another aspect, FIG. 7 is a tank cover using the protector of FIG. 6, and is a cross-sectional view of the fuel tank covered and assembled to the vehicle body, FIG. 8 is a partially enlarged view of FIG. 7, and FIG. 9 shows a heat insulation test result graph. Each figure emphasizes the main part of the invention and omits parts not directly related to the present invention.

[0010] This fuel tank cover 1 includes an insulator 2 made of a foam in which the inner surface 2a of the bowl portion is formed along the outer surface 7b on the lower side of the fuel tank, a bowl-shaped protector 3 that covers the outside of the insulator 2, a first rib 4 and a third rib 6 provided on the protector 3 (FIGS. 1 to 4). As used in the present invention, "lower side" and "downward" refer to "lower side of the paper surface" and "below the paper surface" in FIG. 3.

[0011] The insulator 2 is made of a foam having a predetermined thickness and having heat insulation properties, and is a bowl-shaped three-dimensional shaped part that covers the fuel tank 7 from the lower side as shown in FIG. 3. The insulator 2 is manufactured as follows. A developed member is cut out from a plate body having a predetermined thickness and having heat insulation properties in accordance with the developed shape so as to have the shape of the insulator 2 that covers the lower side of the fuel tank 7. Thereafter, the developed member is made into the insulator 2 that is formed into a bowl shape by an adhesive process. It is also possible to use an insulator 2 that is foam-molded into a bowl shape with a predetermined thickness. For example, an independent bubble type thermoplastic foam sheet may be heated and softened and set in a mold, and then formed into a shape along the outer surface 7b on the lower side of the fuel tank by vacuum forming or pressure air forming.

[0012] The insulator 2 here is made of a closed-cell foamed plastic formed of an olefin-based synthetic resin or a composite material thereof, and is a vacuum-formed product made of a soft foam. "Closed-cell foamed plastic refers to a foamed plastic in which most of the cells are closed." (Illustrated Dictionary of Plastic Terms, 2nd Edition). An independent-cell type polyethylene foam sheet with a thickness of 4 mm to 8 mm is heated and softened, and the insulator 2 is formed by vacuum forming with a vacuum created between the foamed polyethylene sheet and the mold. Reference numeral 23 indicates a peripheral edge that protrudes in a flange shape from the opening edge of the bowl portion formed by the bottom portion 21 and the side portion 22.

[0013] The protector 3 is an injection-molded product resin-molded in a bowl shape covering the outer surface 2b of the bowl portion of the insulator 2, and an annular outer flange 34 that protrudes horizontally outward from the outer peripheral edge 311 of the bowl-shaped portion is provided (FIG. 1). It is made of polypropylene resin or polypropylene resin containing talc and is molded to a thickness of about 1.5 mm to 2.5 mm. Reference numeral 35 indicates a protruding piece extending in an ear shape at the four corners of the outer flange 34, and reference numeral 350 indicates a through hole provided in the protruding piece 35. A first rib 4 is formed on the inner surface 32a of the bottom wall of the bowl-shaped portion 31 of the protector 3.

[0014] The first rib 4 is a protruding portion that is raised and formed on the inner surface 32a of the bottom wall of the protector 3 facing the lower outer surface 71 of the fuel tank through the insulator 2 when the fuel tank cover 1 covering the fuel tank 7 is assembled to the vehicle body 8 (FIG. 3). As shown in FIGS. 1 and 2, the bottom wall 32 of the bowl-shaped portion 31 has a horizontally long elliptical shape, and a plurality of first ribs 4 that protrude in a horizontally long strip shape in the elliptical shape are arranged at a predetermined pitch in the horizontally long direction of the inner surface 32a of the bottom wall, standing in the width direction. The height h1 of the first rib 4 standing in the width direction is set in the range of 5 mm to 15 mm so as to ensure the required layer height of the first space S1 for heat insulation set on the inner surface 32a side of the bottom wall.

[0015] Then, by using the through-hole 350 of the protruding piece 35, the protector 3 covers the fuel tank 7 via the insulator 2 as shown in FIG. 3, and can be assembled and fixed to the vehicle body 8 (specifically, the vehicle body panel) by sandwiching the peripheral edge portion 23 of the insulator between the vehicle body 8. In the figure, reference numeral 9 denotes a fastener for assembling and fixing the protector 3 to the vehicle body 8, reference numeral 91 denotes a bolt provided on the vehicle body 8, and reference numeral 92 denotes a nut having a female screw portion screwed onto the male screw portion of the bolt 91.

[0016] The protector 3 houses the insulator 2 in its bowl 30, covers the fuel tank 7, and is assembled to the vehicle body 8. Then, the bottom lower surface 21b of the insulator 2 is received by the first rib 4 as shown in FIG. 3, and a first space S1 of an air layer is formed between the bottom lower surface 21b of the insulator 2 and the inner surface 32a of the bottom wall of the protector 3. Further, the insulator 2 is made of a soft foam. As shown in FIG. 4, the insulator 2 that has received the load of the fuel tank 7 through its lower outer surface 71 has the bottom lower surface 21b of the insulator 2 biting into the first rib 4 and being supported by the first rib 4. The insulator 2 becomes smaller in thickness from the initial thickness t1 to the thickness t3 at the location where the first rib 4 is present. A first space S1 of an air layer is formed between the bottom lower surface 21b of the insulator and the inner surface 3a of the protector 3 due to the raised structure of the first rib 4. Also, when the fuel tank cover 1 (the protector 3 housing the insulator 2) covering the fuel tank 7 is assembled to the vehicle body 8, the side portion 22 of the insulator 2 is set to interfere with the side outer surface 72 of the fuel tank. In the interference region, when the fuel tank cover 1 is assembled to the vehicle body 8, as shown in FIG. 4, the soft insulator 2 is elastically compressed and deformed from the initial thickness t1 to a thickness t2 smaller than this under the pressure by the rigid fuel tank 7. The portion of the side portion 22 of the elastically compressed and deformed insulator 2 is provided in a shape that goes around the inner surface 33a of the side wall near the bottom wall 32 of the protector as shown in FIG. 4. This is to stop the inflow and outflow of air in the first space S1.

[0017] The first rib 4 is composed only of a plurality of vertical ribs 4A arranged in parallel at a predetermined pitch on the inner surface 32a of the bottom wall of the bowl-shaped portion 31 as shown in FIGS. 1 to 4. Additionally, as shown in FIG. 5 of another embodiment, it is more preferable to provide horizontal ribs 4B intersecting these vertical ribs 4A to form a grid-like first rib 4. The horizontal ribs 4B also stand up in the bandwidth direction on the inner surface 32a of the bottom wall and bulge in a horizontally laid strip shape. The upper standing edges 41 of both the vertical ribs 4A and the horizontal ribs 4B standing up in the bandwidth direction are on the same plane. By forming the grid-like first rib 4, the heat insulation effect is further enhanced.

[0018] In this embodiment, in addition to the first rib 4, a third rib 6 is provided (FIGS. 1 and 2). An outer flange 34 extends horizontally outward from the outer peripheral edge 311 of the bowl-shaped portion. On the upper surface 34a side of the outer flange 34, the third rib 6 is formed to run in the circumferential direction of the outer flange 34. The protruding third rib 6 is provided on the upper surface 34a of the outer flange to go around along the outer peripheral edge 311 of the bowl-shaped portion 31. When the bottom 21 and the side 22 of the insulator 2 are received in the bowl 30 of the protector 3, the peripheral edge 23 of the insulator 2 is configured to rest on the third rib 6 (FIG. 3). By injection molding the protector 3, the third rib 6 is integrally formed with the first rib 4, the bowl-shaped portion 31, and the outer flange 34. When the protector 3 houses the insulator 2 in its bowl 30 and is assembled to the vehicle body 8 covering the fuel tank 7, the lower surface 23b of the peripheral edge of the insulator 2 is received by the third rib 6. Specifically, the soft foam insulator 2 has its third rib 6 bitten into the lower surface 23b of its peripheral edge 23 and is received by the third rib 6. The height h3 of the third rib 6 that bulges in a dike shape on the upper surface 34a of the outer flange is set to a height that can be sealed by the third rib 6. The symbol S3 indicates the third space surrounded by the peripheral edge 23 of the insulator 2, the third rib 6, and the outer flange 34.

[0019] Figure 6 shows a protector 3 in another embodiment. The protector 3 is provided with a second rib 5 in addition to the first rib 4 in Figure 2. Through the insulator 2, a second rib 5 is formed to bulge on the inner surface 33a of the side wall of the protector 3 facing the outer side surface 72 of the fuel tank. When the protector 3 houses the insulator 2 in its bowl 30, covers the fuel tank 7, and is assembled to the vehicle body 8, the outer side surface 22b of the insulator 2 is received by the second rib 5 (Figure 8). The second rib 5, which stands upright in the bandwidth direction and bulges from the inner surface 33a of the side wall of the protector 3 into a horizontally lying strip shape, stands upright with respect to the inner surface 32a of the bottom wall, and its upper end extends near the outer peripheral edge 311 of the bowl-shaped portion. A plurality of the second ribs 5 are arranged at a predetermined pitch in the inner circumferential direction of the side wall 33 of the bowl-shaped portion 31. At the location where the vertical rib 4A of the first rib 4 is arranged on the inner surface 32a of the bottom wall, as shown in the figure, the second rib 5 is connected to the vertical rib 4A of the first rib 4. The height h2 of the second rib 5 in the bandwidth direction is matched to the height h1 of the first rib 4 in the bandwidth direction.

[0020] And when the protector 3 in Figure 6 houses the insulator 2 in its bowl 30, covers the fuel tank 7, and is assembled to the vehicle body 8, the aforementioned first space S1 is formed, and the outer side surface 22b of the insulator 2 is received by the upright upper edge 51 in the bandwidth direction engaging with the second rib 5, forming a second space S2 of an air layer between the outer side surface 22b of the insulator 2 and the inner surface 33a of the side wall of the protector 3 (Figure 7, Figure 8). In this embodiment, when assembling the fuel tank cover 1 covering the fuel tank 7 to the vehicle body 8, an interference portion between the insulator 2 and the fuel tank 7 is provided. Due to such an interference portion, the insulator 2 made of soft foam that receives an interference pressing force through the outer side surface 72 of the fuel tank elastically compresses and deforms itself, and its outer side surface 22b bites into the second rib 5 and is supported by the second rib 5. Then, a second space S2 as shown in Figure 8 is formed between the outer side surface 22b of the insulator 2 and the inner surface 33a of the side wall of the protector 3. The second space S2 formed by the second rib 5 is closed by the peripheral edge portion 23 of the insulator 2 where the opening on the outer peripheral edge 311 side rests on the outer flange 34, becoming a closed space.

[0021] FIG. 9 is a diagram showing the experimental results of comparing the heat insulation performance between the product of the present invention and the conventional product of Patent Document 2. On a hot plate, a plate (thickness 1.5 mm) corresponding to the bottom wall 32 of the protector 3 was placed, and a foamed sheet for the insulator 2 with a thickness of 12 mm was placed on the plate as the conventional product. On the other hand, for the product of the present invention, a plate (thickness 1.5 mm) corresponding to the bottom wall 32 of the protector 3 and a lattice-shaped first rib 4 with a height h1 of 5 mm as shown in FIG. 5 were integrally formed, and a foamed sheet for the insulator 2 with a thickness of 7 mm was placed on the first rib 4, and this was placed on the hot plate. The foamed sheets for the insulator 2 with a thickness of 12 mm and a thickness of 7 mm both used a closed-cell type foamed polyethylene sheet and had the same area as the plate corresponding to the bottom wall 32 of the protector 3.

[0022] Then, the temperature of the hot plate was adjusted to 60° C., and the temperature at the central point on the upper surface of both foamed sheets for the insulator 2 was measured using a thermocouple. FIG. 9 shows the change in the measured temperature with the time axis on the horizontal axis and the vertical axis. According to the results of this experiment, the product of the present invention, which includes the first rib 4 with a height of 5 mm from the inner surface 32a of the bottom wall and the foamed sheet for the insulator 2 with a thickness of 7 mm, has heat insulation performance comparable to that of the conventional product with a thickness of 12 mm from the inner surface 32a of the bottom wall. Even if the thickness of the insulator 2 is reduced and the reduced portion is replaced by the first rib 4, the heat insulation performance remains substantially the same.

[0023] When the fuel tank cover 1 configured as described above is assembled to the vehicle body 8 covering the fuel tank 7, the bottom lower surface 21b of the insulator 2 is received by the first rib 4, and a first space S1 is formed between the bottom lower surface 21b of the insulator 2 and the inner surface 32a of the bottom wall of the protector 3. Therefore, good heat insulation can be ensured by an air layer with a low thermal conductivity that fills the first space S1. In particular, in summer, the ground reflection is strong, and the radiant heat is properly received by the outer surface 3b of the protector 3, especially the bottom wall 32. However, by simply providing a simple first rib 4 on the inner surface 32a of the bottom wall, a first space S1 in which an air layer with a low thermal conductivity accumulates is formed, suppressing the temperature rise. The heat insulation effect is high and the cost can be reduced. As shown in Fig. 9, the reduced thickness of the insulator 2 can be replaced by the thickness of the first space S1, reducing the usage amount of the insulator 2 to achieve cost reduction while exhibiting a sufficient heat insulation effect similar to that of the fuel tank cover of Patent Document 2. Furthermore, since the usage amount of the insulator 2 can be reduced, it also contributes to weight reduction.

[0024] When the foam of the insulator 2 is made of a closed-cell foamed plastic and formed of an olefin-based synthetic resin or a composite material thereof, the insulator 2 itself can also ensure good heat insulation by the closed-cell foamed plastic in which the bubbles are arranged independently. Olefin-based synthetic resins or composite materials thereof such as closed-cell polyethylene foam have fine bubbles, flexibility, resilience, and some have high elasticity. When the insulator 2 is such a soft foam and the first rib 4 bites into the bottom lower surface 21b of the insulator 2 and is received by the first rib 4, the sealing property at the contact portion between the insulator 2 and the first rib 4 is enhanced. Therefore, the air in the air layer in the first space S1 stays in place, and the heat insulation effect can be further enhanced.

[0025] Furthermore, when the fuel tank cover 1 covering the fuel tank 7 is assembled to the vehicle body 8 such that the side portion 22 of the insulator 2 interferes with the outer side surface 72 of the fuel tank, as shown in FIG. 4, the insulator 2 is elastically compressed and deformed from the initial thickness t1 to a smaller thickness t2 by the pressing due to the interference received from the highly rigid fuel tank 7 side, thereby sealing the insulator 2. As a result, the air in the first space S1 cannot flow in or out. Since air does not flow into the gap as in Patent Document 1 and there is no movement of air in the gap (here, the first space S1), a problem such as a reduction in the heat insulation effect does not occur. Further, when the first rib 4 is formed in a lattice shape by the vertical rib 4A and the horizontal rib 4B to form the first space S1, the upper surface opening of the first space S1 surrounded by the vertical rib 4A and the horizontal rib 4B in a lattice shape is blocked by the insulator 2, forming a closed space of the first space S1 surrounded by the lattice frame and further enhancing the heat insulation effect.

[0026] Furthermore, when the protector 3 is further provided with a second rib 5 formed in a raised shape on the inner surface 33a of the side wall of the protector 3 facing the outer side surface 72 of the fuel tank, a second space S2 in which an air layer having a low thermal conductivity accumulates can be formed between the outer side surface 22b of the insulator 2 and the inner surface 33a of the side wall of the protector 3. When the protector 3 houses the insulator 2 in its bowl 30, covers the fuel tank 7, and is assembled to the vehicle body 8, the outer side surface 22b of the insulator 2 is received by the second rib 5, and a second space S2 of an air layer having high heat insulation can be provided between the outer side surface 22b of the insulator 2 and the inner surface 33a of the side wall of the protector 3. Since the first space S1 and the second space S2 filled with the air layer having a low thermal conductivity cover not only the lower outer surface 71 of the fuel tank but also the outer side surface 22b as shown in FIG. 7, a fuel tank cover 1 having extremely excellent heat insulation performance like a thermos bottle is completed.

[0027] In addition, a protector 3 having a peripheral edge portion 23 on the insulator 2 and provided with a third rib 6 running in the circumferential direction of the outer flange 34 houses the insulator 2, covers the fuel tank 7, and is assembled to the vehicle body 8. When the lower surface 23b of the peripheral edge portion of the insulator 2 is received by the third rib 6, sealing performance is exhibited by the contact between the peripheral edge portion 23 and the third rib 6. When the sealing performance between the third rib 6 and the peripheral edge portion 23 is exhibited, if there is air in the first space S1 and further a second space S2, the air in the space is prevented from flowing out of the insulator 2, or air having heat in summer, for example, from flowing into the insulator 2 from the outside of the insulator 2 at the location of the third rib 6. Further, when the insulator 2 is made of a soft material and the third rib 6 bites into the lower surface 23b of the peripheral edge portion and the peripheral edge portion 23 is received by the third rib 6, the peripheral edge portion 23 functions as a packing, and the sealing performance there is fully exhibited. As shown in FIGS. 1 and 5, if the third rib 6 is wound in the circumferential direction of the outer flange 34, the sealing performance becomes rock-solid, and the fuel tank cover 1 having more effective heat insulation performance is obtained.

[0028] In the present invention, the present invention is not limited to that shown in the above embodiment, and various modifications can be made within the scope of the present invention according to the purpose and application. The shapes, sizes, numbers, materials, etc. of the insulator 2, protector 3, first rib 4, second rib 5, third rib 6, fuel tank 7, etc. can be appropriately selected according to the application. For example, although the upper surface 34a of the outer flange 34 related to the protector 3 of the embodiment is made flush, it can also be formed on an outer flange 34 that projects horizontally from the outer peripheral edge with undulations provided on the outer peripheral edge 311 of the bowl-shaped portion.

Explanation of Reference Numerals

[0029] 1 Fuel tank cover 2 Insulator 21b Bottom lower surface 22 Side portion 23 Peripheral edge portion 3 Protector 30 Inside the bowl 32a Inner surface of the bottom wall 33a Inner surface of the side wall 4 First rib 5 Second rib 6 Third rib 7 Fuel tank 71 Lower outer surface of the fuel tank 72 Side outer surface of the fuel tank 8 Vehicle body S1 First space S2 Second space

Claims

1. A protector for a fuel tank cover including an insulator, wherein the protector is made of resin in a bowl shape, has a plurality of first ribs formed in a raised manner on the inner surface of the bottom wall, and covers the outside of the insulator formed along the outer surface of the lower side of the fuel tank.

2. The protector according to claim 1, further comprising second ribs formed in a raised manner on the inner surface of the side wall.

3. The protector according to claim 1 or 2, wherein an annular outer flange projecting horizontally outward is formed from the outer peripheral edge of the bowl-shaped portion of the protector, and third ribs extending in the circumferential direction are formed on the upper surface of the outer flange.

Images