JP6831654B2 - Bolt fastening structure for resin parts - Google Patents

Description

The present invention relates to a bolt fastening structure of a resin component, and more particularly to a bolt fastening structure of a resin component when a resin component such as a cover is bolted and attached to an automobile component such as an engine.

As part of improving vehicle fuel efficiency, engine cylinder head covers (also called rocker covers, cam covers, etc.), chain covers, oil pans, or transmission hydraulic control unit covers, oil pans, etc. are made of conventional heavy metal. In some cases, the weight of the engine, transmission, etc. may be reduced by replacing the lighter resin material.

Then, when the resin part such as the cover is fastened to the attached member such as the cylinder head of the engine with bolts and attached, a metal bolt is inserted into the bolt hole provided in the resin part to attach the resin part to the attached member. When fastened, the resin parts may be damaged or the fastened portion may be loosened. Therefore, for example, Patent Documents 1 and 2, etc. propose a bolt fastening structure for resin parts that prevents the occurrence of such a problem.

JP-A-2007-263300 JP-A-2015-31316

However, in the research by the present inventors, in the bolt fastening structure of the resin component as described in Patent Documents 1 and 2, the attached member to which the resin component is attached is a member such as an engine which can have a high temperature. In some cases, it is known that when the temperature of the attached member becomes high, loosening or the like may occur in the portion where the resin component is fastened with the metal bolt.

It is also known that, for example, when sealing between a resin component and a member to be attached with rubber or the like, the function of the seal may deteriorate at the fastening portion when the member to be attached becomes hot. When such a symptom appears, problems such as engine oil leaking from the bolt fastening portion and harmful gas such as blow-by gas in the cylinder head leaking out may occur.

The present invention has been made in view of the above problems, and accurately prevents loosening or the like from occurring at the fastening portion when the resin component is fastened to the mounted member with a metal bolt and mounted. It is an object of the present invention to provide a bolt fastening structure of a resin part capable of being capable of.

In order to solve the above problem, the invention according to claim 1 is
A metal stepped bolt having a cylindrical part formed with a diameter larger than the nominal diameter of the thread part,
Resin parts that are fastened to and attached to the member to be attached by the stepped bolts ,
It is a bolt fastening structure of resin parts equipped with
A collar made of the same metal as the stepped bolt is arranged around the bolt hole including the inner wall surface of the bolt hole drilled in the resin part, and the coefficient of linear expansion of the portion is high. , It is formed so as to have the same coefficient of linear expansion as that of the stepped bolt.
In the surface direction of the mounting surface of the mounted member to which the resin component is mounted, the head of the fastened stepped bolt or the end of the flange should not protrude outside the collar arranged in the portion. It is composed and
The resin component is a cover or oil pan that is attached to the engine or transmission of a vehicle.
The collar is characterized by being composed of a cylindrical member .

The invention according to claim 2 is characterized in that, in the bolt fastening structure of the resin component according to claim 1 , the stepped bolt is formed of aluminum or an aluminum alloy.

According to the present invention, when a resin part is fastened to a member to be attached with a metal bolt and attached, it is possible to accurately prevent loosening or the like from occurring at the fastened portion.

It is a figure which shows the example of the resin component such as a cover which a sealing material is fitted in the peripheral edge part, and is arranged around a bolt hole. It is schematic cross-sectional view which shows the structure of the bolt fastening structure of the resin part which concerns on 1st Embodiment, and shows (A) the case without a seal material, and (B) the case with a seal material. It is a figure which shows the state which (A) thermal deformation occurred, and (B) the part of a stepped bolt remains recessed in the bolt fastening structure of the conventional resin part without a sealing material. It is a figure which shows the state which (A) thermal deformation occurred in the bolt fastening structure of the conventional resin part with a sealing material, and (B) the state where the stepped bolt portion remains recessed and the sealing function deteriorates. It is a figure which shows the state which the thermal deformation occurred in the bolt fastening structure of the resin part which concerns on 1st Embodiment, and shows (A) the case without a seal material, and (B) the case with a seal material. It is schematic cross-sectional view which shows the structure of the bolt fastening structure of the resin part which concerns on 2nd Embodiment, and shows (A) the case without a seal material, and (B) the case with a seal material. (A) Displacement amount when vibration occurs in the cover, (B) Displacement amount in the thickness direction of the sealing material, (C) Displacement amount obtained by adding (A) and (B) displacement amount. Is.

Hereinafter, embodiments of a bolt fastening structure for resin parts according to the present invention will be described with reference to the drawings.

In the present invention, there is a case where the resin component and the member to be attached are sealed with a sealing material, or a case where the resin component is not sealed by them and the resin component is directly attached to the member to be attached. Also applies to. Hereinafter, the former case will be abbreviated as “with sealing material” and the latter case will be abbreviated as “without sealing material”, and both cases will be described.

In the case where there is a sealing material, for example, as shown in FIG. 1, the sealing material 12 made of rubber, elastomer, or the like is fitted into a groove 13 provided in the peripheral portion of the resin component 10 such as a cover. A case where the resin component 10 and the attached member 20 (not shown in FIG. 1) are sealed by the sealing material 12 by being arranged around the bolt holes 11 will be described.

Further, when the schematic cross-sectional view with the sealing material is shown in each of the following figures, the schematic cross-sectional view taken along the line XX in FIG. 1 is shown. In each of the following figures, the case where the resin component 10 is attached to the attached member 20 from above will be described, but the case where the resin component 10 is attached to the attached member 20 from below or from the side will also be described in the same manner. Will be done.

[First Embodiment]
Hereinafter, the bolt fastening structure of the resin component according to the first embodiment of the present invention will be described. 2 (A) and 2 (B) show the bolt fastening structure of the resin component according to the first embodiment (FIG. 2 (A) shows the case without the sealing material, and FIG. 2 (B) shows the case with the sealing material). It is the schematic sectional drawing shown. In the present embodiment, the bolt fastening structure 100 of the resin component includes the metal stepped bolt 1 and the resin component 10 described above that is fastened to and attached to the attached member 20 by the stepped bolt 1.

The stepped bolt 1 has a threaded portion 2, a cylindrical portion 3, and a head portion 4. In this embodiment, as shown in FIGS. 2A and 2B, a case where the stepped bolt 1 is provided with the flange 5 will be described, but the flange 5 is not necessarily provided. Further, in the stepped bolt 1, the cylindrical portion 3 is formed to have a diameter larger than the nominal diameter of the screw portion 2, and the diameter of the flange 5 (the diameter of the head 4 when the flange 5 is not provided) is the cylindrical portion. It is formed larger than the diameter of 3.

Then, the stepped bolt 1 is inserted into the bolt hole 11 formed in the resin component 10, and when the threaded portion 2 is screwed into the female threaded portion 21 formed in the attached member 20, FIG. 2A is shown. In the case of no sealing material, the resin component 10 and the attached member 20 are fastened by pressing the resin component 10 against the attached member 20 with the flange 5 (or the head 4).

Further, in the case of the case with the sealing material shown in FIG. 2B, when the stepped bolt 1 is screwed, the flange 5 (or the head 4) pushes the resin component 10 toward the attached member 20 side, and the sealing material 12 Is pressed against the attached member 20, and the resin component 10 and the attached member 20 are fastened in a state where the sealing material 12 maintains the airtightness.

In addition, in FIGS. 2 (A) and 2 (B) and each of the following drawings, the case where the cylindrical portion 3 of the stepped bolt 1 and the inner wall surface of the bolt hole 11 are in contact with each other is described. It is also possible to provide a gap having a predetermined width between the cylindrical portion 3 of 1 and the inner wall surface of the bolt hole 11.

On the other hand, in the present embodiment, in the resin component 10, the portion around the bolt hole 11 including the inner wall surface of the bolt hole 11 (see the portion A in the drawing) is the resin constituting the resin component 10 with the glass fiber 14. It is formed so as to be embedded. At that time, in this portion A, the glass fiber 14 is embedded in the resin in a state of being oriented in the direction along the axial direction of the stepped bolt 1.

That is, in the present embodiment, the portion A around the bolt hole 11 of the resin component 10 is in a state like a glass fiber reinforced resin in which the glass fiber 14 is oriented in the direction along the axial direction of the stepped bolt 1. There is. The coefficient of linear expansion αA in the portion A is configured to be the same as the coefficient of linear expansion α1 of the metal stepped bolt 1.

When the coefficient of linear expansion αA of the portion A is the same as the coefficient of linear expansion α1 of the stepped bolt 1, it does not have to be exactly the same, and the fastening portion according to the fastening structure 100 of the present embodiment will be described later. It may be the same as long as it is possible to realize a state in which gas leakage, oil leakage, etc. do not occur from the bolt fastening portion due to loosening or deterioration of the sealing function. Hereinafter, the wording "same" with respect to the coefficient of linear expansion α is used in this sense.

Then, in the present embodiment, the flange 5 of the stepped bolt 1 fastened in the surface direction of the mounting surface 20A of the mounted member 20 to which the resin component 10 is mounted (horizontal direction in FIGS. 2A and 2B) ( Alternatively, the end portion of the head portion 4) is configured so as not to protrude outside the portion A around the bolt hole 11 of the resin component 10 in which the glass fiber 14 is embedded.

That is, the length from the cylindrical surface of the cylindrical portion 3 of the portion where the flange 5 (or the head 4) of the stepped bolt 1 protrudes outward from the cylindrical portion 3 is equal to or less than the width of the above-mentioned portion A (that is, the bolt hole 11). It is configured to have a length (less than or equal to the length from the inner wall surface of the above portion A to the outermost portion of the portion A).

[Action]
Next, before explaining the operation of the bolt fastening structure 100 of the resin component according to the present embodiment, the cause of loosening of the fastening portion and deterioration of the sealing function in the conventional bolt fastening structure 200 of the resin component will be described. The bolt fastening structure 200 of the conventional resin component has the same overall configuration as the bolt fastening structure 100 of the resin component according to the present embodiment, but the present invention is in that the glass fiber is not embedded in the resin component. It will be described as different from the embodiment.

In the conventional bolt fastening structure 200 of a resin part without a sealing material, heat is applied to the part of the fastening structure in the same state as shown in FIG. 2 (A) (however, the glass fiber is not embedded in the resin part). When added, as shown in FIG. 3A, both the stepped bolt 1 and the resin component 10 expand to cause thermal deformation. However, at that time, the linear expansion coefficient α10 of the resin component 10 is larger than the linear expansion coefficient α1 of the metal stepped bolt 1.

Therefore, as shown in FIG. 3A, the resin component 10 is significantly deformed in the portion of the resin component 10 that is not pressed by the stepped bolt 1, but the portion that is pressed by the stepped bolt 1. Then, the resin component 10 can be deformed only by the amount of deformation of the stepped bolt 1. Then, for example, when the operating time of the vehicle is long and the engine or the like continues to be in a high temperature state for a long time, the resin component 10 has a shape shown in FIG. 3 (A) (that is, the resin component 10 is recessed at the stepped bolt 1 portion). It imitates the shape). That is, so-called creep deformation occurs in which the resin component 10 remembers this shape, so to speak.

Then, even if the temperature drops in this state and the stepped bolt 1 and the resin component 10 shrink, the resin component 10 does not return to the flush state as shown in FIG. 2 (A), and FIG. 3 (B) shows. As shown in, the shape is recessed at the stepped bolt 1. That is, the resin component 10 remains shrunk at the stepped bolt 1. Therefore, looseness occurs in the fastening portion.

Further, in the conventional bolt fastening structure 200 of a resin part with a sealing material, for example, in the same state as shown in FIG. 2 (B) (however, the glass fiber is not embedded in the resin part) in the part of the fastening structure. When heat is applied, as shown in FIG. 4 (A), both the stepped bolt 1 and the resin component 10 expand to cause thermal deformation, and when the high temperature state continues for a long time, the resin component 10 changes to FIG. 4 (A). A creep deformation occurs that follows the shape shown in (that is, the shape in which the resin component 10 is recessed at the portion of the stepped bolt 1).

Then, even if the temperature drops in this state and the stepped bolt 1 and the resin component 10 shrink, the resin component 10 does not return to the flush state as shown in FIG. 2 (B), and FIG. 4 (B) shows. As shown in, the shape is recessed at the stepped bolt 1. In this case, since the resin part 10 is pressed against the flange 5 (or the head 4) of the stepped bolt 1 by the elastic force of the sealing material 12, it seems that the fastening portion is not loosened at first glance, but the resin. The part 10 is in a state of being shrunk at the portion of the stepped bolt 1.

Therefore, the pressing force of the resin component 10 on the sealing material 12 decreases, so that the compressibility of the sealing material 12 decreases and the sealing function deteriorates. As can be seen by comparing FIG. 2 (B) and FIG. 4 (B), in the state of FIG. 4 (B), the distance between the resin component 10 and the attached member 20 is wider than in the case of FIG. 2 (B). It has been done. Then, in the conventional bolt fastening structure 200 of the resin part, the sealing function by the sealing material 12 is deteriorated, so that gas leakage, oil leakage, and the like may occur.

On the other hand, in the bolt fastening structure 100 of the resin component according to the present embodiment, when heat is applied to the portion of the fastening structure in the state of FIGS. 2A and 2B, it is shown in FIGS. 5A and 5B. As described above, both the stepped bolt 1 and the resin component 10 expand to cause thermal deformation.

At that time, in the conventional bolt fastening structure 200 of the resin part, the resin part 10 of the portion pressed by the stepped bolt 1 has a larger linear expansion coefficient α than the stepped bolt 1, so that it is essentially I want to expand the resin part 10 of the other part (that is, the part that is not pressed by the stepped bolt 1) as much as the resin part 10, but it cannot be expanded by pressing, so in FIGS. 3 (A) and 4 (A) The molecular structure in the state is memorized, and as shown in FIGS. 3 (B) and 4 (B), the recessed shape of the stepped bolt 1 of the resin component 10 remains (that is, creep deformation). have done.).

However, in the bolt fastening structure 100 of the resin component according to the present embodiment, even if heat is applied to the portion of the fastening structure and the stepped bolt 1 and the resin component 10 expand to cause thermal deformation, the glass around the bolt hole 11 Since the linear expansion coefficient αA of the portion A in which the fiber 14 is embedded is the same as the linear expansion coefficient α1 of the stepped bolt 1, the above-mentioned portion A of the resin component 10 expands only to the same extent as the stepped bolt 1. Since it does not, creep deformation does not occur.

Then, when the temperature drops after the high temperature state continues, the above-mentioned portion A of the resin component 10 shrinks in the same manner as the stepped bolt 1. Therefore, in the present embodiment, the portion of the stepped bolt 1 of the resin component 10, that is, the above-mentioned portion A is not dented due to creep deformation as in the conventional case, and when the temperature is lowered, the original portions FIG. 2 (A), ( It returns to the state shown in B).

The parts other than the part A of the resin part 10 are the steps fastened in the surface direction of the mounting surface 20A of the mounted member 20 to which the resin part 10 is mounted (horizontal direction in FIGS. 2A and 2B). Since the end of the flange 5 (or the head 4) of the attached bolt 1 is configured so as not to protrude outside the peripheral portion A of the bolt hole 11 of the resin component 10 in which the glass fiber 14 is embedded, heat is generated. Since the stepped bolt 1 does not hold down even if thermal deformation occurs due to the addition of, creep deformation does not occur. Since the linear expansion coefficient of the portion A around the bolt hole 11 and the portion other than the portion A of the resin component 10 are different, the thickness of the portion other than the portion A of the resin component 10 is the original state of FIGS. 2 (A) and 2 (B). Although it may be slightly thicker than the thickness of (that is, the bulge may remain), at least in the above-mentioned part A, creep deformation does not occur, so if the temperature drops, the original FIGS. 2 (A) and 2 (B) ) Returns to the state.

Therefore, in the bolt fastening structure 100 of the resin component according to the present embodiment, even if the temperature of the fastening structure portion becomes high or drops to the outside air temperature, the resin component 10 is the portion of the stepped bolt 1 as in the conventional case. The original state (thickness) is maintained without A being shrunk. Therefore, the state in which the resin component 10 is appropriately pressed against the mounted member 20 side by the stepped bolt 1 is maintained.

[effect]
As described above, according to the bolt fastening structure 100 of the resin component according to the present embodiment, even if the temperature of the fastening structure portion becomes high or drops to the outside air temperature due to the engine becoming hot or the like, the bolts The original state (thickness) is maintained without the portion A of the resin component 10 in which the glass fiber 14 is embedded around the hole 11, that is, around the stepped bolt 1, remains shrunk.

Therefore, in the bolt fastening structure 100 of the resin component according to the present embodiment, the resin component 10 is appropriately pressed against the mounted member 20 by the stepped bolt 1 even if the temperature of the fastening structure portion rises or falls. Be maintained. That is, the decrease in the force (that is, the axial force) that the flange 5 (or the head 4) of the stepped bolt 1 pushes the portion A of the resin component 10 in the axial direction can be made zero.

Therefore, when the resin component 10 is fastened to the attached member 20 with the metal stepped bolt 1 and attached, it is possible to accurately prevent loosening or deterioration of the sealing function at the fastened portion. , It is possible to accurately prevent gas leakage, oil leakage, etc. from the bolt fastening portion.

In the research by the present inventors, when the glass fiber 14 is embedded in the resin of the above-mentioned portion A of the resin component 10 in a state of being oriented along the axial direction of the stepped bolt 1, the linear expansion of the portion A is performed. It is known that the coefficient αA can be made the same as the coefficient of linear expansion α of aluminum or an aluminum alloy. Therefore, the stepped bolt 1 can be formed of aluminum or an aluminum alloy. It is also possible to form the stepped bolt 1 with another metal.

[Second Embodiment]
On the other hand, instead of being configured so that the glass fiber 14 is embedded in the resin of the portion A around the bolt hole 11 in the resin component 10 as in the first embodiment described above, FIGS. 6A and 6B As shown in the above, it is also possible to dispose a collar 15 (that is, a cylindrical member) made of the same metal as the stepped bolt 1 in the portion A around the bolt hole 11 of the resin component 10. Is.

For example, the collar 15 can be press-fitted into the bolt hole 11 of the resin component 10 and arranged in the portion A. Further, FIG. 6A shows a case without a sealing material, and FIG. 6B shows a case with a sealing material.

Then, also in the second embodiment, the flange 5 of the stepped bolt 1 fastened in the surface direction of the mounting surface 20A of the mounted member 20 to which the resin component 10 is mounted (the head if the flange 5 is not provided). The end portion of 4) is configured so as not to protrude outside the collar 15 arranged in the portion A.

Even with this configuration, when heat is applied to the portion of the fastening structure and the stepped bolt 1 and the resin component 10 expand to cause thermal deformation, the linear expansion coefficient α15 of the collar 15 becomes the stepped bolt 1. Since it is the same as the linear expansion coefficient α1 of No. 1, the above-mentioned portion A in which the collar 15 is arranged expands in the same manner as the stepped bolt 1.

Then, when the temperature drops after the high temperature state continues, the above-mentioned portion A on which the collar 15 is arranged shrinks in the same manner as the stepped bolt 1. Therefore, also in the present embodiment, the portion of the stepped bolt 1 of the resin component 10, that is, the above-mentioned portion A is not dented as in the conventional case, and when the temperature is lowered, the original portions (A) and 6 (B) are shown. It returns to the state shown in.

Also in this case, with respect to the portion of the resin component 10 other than the collar 15 (that is, the portion other than the portion A of the resin component 10), the surface direction of the mounting surface 20A of the mounted member 20 to which the resin component 10 is mounted (FIG. 2 (FIG. 2). In (A) and (B) in the lateral direction), the end of the flange 5 (or head 4) of the fastened stepped bolt 1 is the portion around the bolt hole 11 of the resin part 10 in which the collar 15 is embedded. Since it is configured so that it does not come out from A, even if heat is applied and thermal deformation occurs, pressing by the stepped bolt 1 does not occur, so that creep deformation does not occur. Since the linear expansion coefficient of the portion A around the bolt hole 11 and the portion other than the portion A of the resin component 10 are different, the thickness of the portion other than the portion A of the resin component 10 is the original state of FIGS. 6 (A) and 6 (B). Although it may be slightly thicker than the thickness of (that is, the bulge may remain), at least the collar 15 of the above portion A has not undergone creep deformation, so if the temperature drops, the original FIG. 6 (A) , (B) returns to the state.

As described above, even in the bolt fastening structure 100 of the resin component according to the present embodiment, even if the temperature of the fastening structure portion becomes high or drops to the outside air temperature, the resin component 10 is the portion of the stepped bolt 1. A (the portion of the collar 15 in this embodiment) maintains the original state (thickness). Therefore, even if the temperature of the portion of the fastening structure rises or falls, the state in which the resin component 10 is appropriately pressed against the mounted member 20 by the stepped bolt 1 is maintained.

Therefore, when the resin component 10 is fastened to the attached member 20 with the metal stepped bolt 1 and attached, it is possible to accurately prevent loosening or deterioration of the sealing function at the fastened portion. , It is possible to accurately prevent gas leakage, oil leakage, etc. from the bolt fastening portion.

[Further effects with sealing material]
Of the bolt fastening structures 100 of the resin parts in the first and second embodiments described above, when there is a sealing material shown in FIGS. 2 (B) and 6 (B), the following is further applied. It is possible to obtain an advantageous vibration / noise reduction effect.

For example, when the resin component 10 is a cover such as a cylinder head cover or a chain cover of an engine, it is assumed that the vibration of the engine causes vibration as shown in FIG. 7 (A) at a position of the cover. In this case, when the compressibility of the sealing material 12 (the reciprocal of the volume elasticity) is low, the sealing material 12 is thickened in the thickness direction (FIGS. 2B and 4B) as shown by the solid line in FIG. 7B. , In the vertical direction in FIG. 6B), the cover (that is, the resin component 10) is largely displaced so as to cancel the vibration. However, when the compressibility of the sealing material 12 is high, a broken line is shown in FIG. 7B. As shown by, the amount of displacement of the sealing material 12 in the thickness direction becomes small.

Therefore, as shown by the solid line in the graph of FIG. 7C, which is the sum of the graphs of FIGS. 7A and 7B, when the compression ratio of the sealing material 12 is low, more vibration of the cover is canceled out. The amount of displacement of the primary delay that suppresses vibration (so-called damper effect) becomes large, and the effect of reducing vibration / noise of the cover (that is, the resin component 10) by the sealing material 12 becomes large.

However, when the compression ratio of the sealing material 12 is high, the degree to which the vibration of the cover is canceled is reduced as shown by the broken line in the graph of FIG. 7 (C), and the displacement amount of the primary delay for suppressing the vibration is reduced. The effect of reducing the vibration and noise of the cover (that is, the resin component 10) by the sealing material 12 is reduced.

On the other hand, in the conventional bolt fastening structure 200 of a resin part, as shown in FIG. 4A, thermal deformation occurs when the portion of the fastening structure becomes high temperature, and the resin component 10 is recessed in the portion of the stepped bolt 1. Since creep deformation occurs, the sealing function deteriorates as shown in FIG. 4 (B). Then, in order to prevent deterioration of the sealing function, for example, in the sealing material 12 attached to the cover shown in FIG. 1, the compressibility of the sealing material 12 is close to the bolt hole 11 fastened by the stepped bolt 1. (That is, it is necessary to reduce the volume modulus).

When the compression rate is increased in a part of the sealing material 12 (that is, the portion close to the bolt hole 11) and the compression rate is decreased in the other part, the compression rate of the sealing material 12 is increased as a whole. Not uniform. Further, in order to make the compressibility of the sealing material 12 uniform as a whole, it is necessary to increase the compressibility of the sealing material 12 as a whole. However, in any case, the damper effect of the sealing material 12 is small in the portion where the compression ratio of the sealing material 12 is high, and the vibration / noise reduction effect of the sealing material 12 is obtained as shown by the broken line in FIG. 7 (C). Since it is low, in the end, in the conventional bolt fastening structure 200 of the resin component, the effect of reducing vibration and noise by the sealing material 12 is reduced.

On the other hand, in the bolt fastening structure 100 (see FIGS. 2B and 6B) of the resin component according to the first and second embodiments, the temperature of the fastening structure portion becomes high as described above. However, since the resin component 10 is not permanently deformed in the portion A around the bolt hole 11 of the resin component 10, the sealing function of the sealing material 12 is not deteriorated.

Therefore, in the bolt fastening structure 100 of the resin component according to the first and second embodiments, the compressibility of the sealing material 12 can be lowered (that is, the volume elastic modulus can be increased), and the sealing material 12 can be increased. As shown by the solid line in FIG. 7C, the damper effect is increased, and an advantageous effect is obtained such that the sealing material 12 can maintain or improve the high vibration / noise reduction effect. Be done.

It is possible to obtain the same advantageous effect when the resin component 10 is an oil pan attached to a vehicle engine or a transmission.

Further, it goes without saying that the present invention is not limited to the above-described embodiments and the like, and can be appropriately modified as long as the gist of the present invention is not deviated.

1 Stepped bolt 2 Threaded part 3 Cylindrical part 4 Head 5 Flange 10 Resin part 11 Bolt hole 12 Sealing material 14 Glass fiber 15 Color 20 Attached member 20A Mounting surface 100 Bolt fastening structure of resin part A Peripheral part of bolt hole Linear expansion coefficient of α1 stepped bolt αA Linear expansion coefficient of part A

Claims (2)

A metal stepped bolt having a cylindrical part formed with a diameter larger than the nominal diameter of the thread part,
Resin parts that are fastened to and attached to the member to be attached by the stepped bolts ,
It is a bolt fastening structure of resin parts equipped with
A collar made of the same metal as the stepped bolt is arranged around the bolt hole including the inner wall surface of the bolt hole drilled in the resin part, and the coefficient of linear expansion of the portion is high. , It is formed so as to have the same coefficient of linear expansion as that of the stepped bolt.
In the surface direction of the mounting surface of the mounted member to which the resin component is mounted, the head of the fastened stepped bolt or the end of the flange should not protrude outside the collar arranged in the portion. It is composed and
The resin component is a cover or oil pan that is attached to the engine or transmission of a vehicle.
The collar is a bolt fastening structure of a resin component characterized by being composed of a cylindrical member . The bolt fastening structure for a resin component according to claim 1 , wherein the stepped bolt is made of aluminum or an aluminum alloy.

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