Component fastening structure

Abstract

To suppress reduction in the holding force of a resin component that is being fastened even if a creep occurs in the resin component.SOLUTION: A first fastening hole 22 is bored in a CFRP component 20, which is a resin component. A second fastening hole 52 is bored in a metal component 50. The second fastening hole 52 is axially aligned with the first fastening hole 22. Furthermore, the second fastening hole 52 is smaller than the first fastening hole 22 in diameter. An insertion hole 66 is bored in a collar 60 in a coaxial direction coaxial with the first fastening hole 22 and the second fastening hole 52. Furthermore, the collar 60 is inserted into the first fastening hole 22. A bolt 10 is inserted into the insertion hole 66 and the second fastening hole 52. The bolt 10 is inserted into an elastic body ring 40. The elastic body ring 40 has an outer diameter R8 exceeding a diameter R2 of the first fastening hole. Furthermore, the elastic body ring 40 is sandwiched between an axial end part 68 of the collar 60, the CFRP component 20, a GFRP component 30 and the metal component 50.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification discloses a component fastening structure including a resin component in the components to be fastened.

Background Art

[0002] When fastening a plurality of components by bolting, a compressive force is applied to the components. Also, a tensile force is applied to the bolts. When a resin component is included in the components, creep may occur in the resin component. Creep refers to a phenomenon in which a component is deformed when a compressive force is applied for a long time. When the resin component becomes thinner due to creep, the fastening load decreases. That is, so-called loosening of the fastening load may occur due to creep.

[0003] Therefore, for example, in Patent Document 1, when fastening a resin material and a metal material, a collar with a flange is used. The collar is a metal component. Also, the collar is inserted into the fastening hole of the resin material. The length of the collar in the fastening direction is configured to be longer than the thickness of the resin material. The axial end of the collar abuts against the metal material to be fastened. Further, a ring-shaped adhesive member is inserted between the flange of the collar and the resin component. Even if the resin component becomes thinner due to creep, so-called metal touch is ensured by the metal collar, and loosening of the fastening load is suppressed. Further, the resin material is adhered to the collar by the adhesive member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when a resin material is held in place by an adhesive member, the fixation of the resin material depends on the adhesive strength of the adhesive member. For example, the adhesive used in the adhesive member may have properties that reduce its adhesive strength at high temperatures. In such cases, the holding of the resin material may become unstable.

[0006] Therefore, this specification discloses a component fastening structure that can suppress a decrease in the holding force of a resin component even if creep occurs in the resin component to be fastened. [Means for solving the problem]

[0007] This specification discloses a component fastening structure comprising a resin component, a metal component, a collar, a bolt, and an elastic ring. A first fastening hole is drilled in the resin component. A second fastening hole is drilled in the metal component. The second fastening hole is axially aligned with the first fastening hole. Furthermore, the second fastening hole has a smaller diameter than the first fastening hole. The metal component is also stacked with the resin component. An insertion hole is drilled in the collar coaxially with the first and second fastening holes. The outer diameter of the collar is less than or equal to the diameter of the first fastening hole and greater than the diameter of the second fastening hole. Furthermore, the collar is inserted into the first fastening hole. A bolt is inserted into the insertion hole and the second fastening hole. The bolt fastens the resin component to the metal component. A bolt is inserted into the elastic ring. Furthermore, the outer diameter of the elastic ring exceeds the diameter of the first fastening hole. Furthermore, the elastic ring is sandwiched between the axial end of the collar and the resin component and the metal component.

[0008] When the resin part deforms to a thinner state due to creep, the bolt shaft, which was stretched by tensile force, contracts. Consequently, the collar compresses the elastic ring. The compressed elastic ring is pushed radially outward. This pushing of the elastic ring lifts the resin part. This allows the bolt displacement to be kept below the amount of wall thinning in the resin part due to creep. [Effects of the Invention]

[0009] The component fastening structure disclosed herein makes it possible to suppress a decrease in the holding force of a resin component even if creep occurs in the resin component. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view illustrating a component fastening structure according to this embodiment. [Figure 2] This is a cross-sectional view illustrating what happens when creep occurs in a resin part. [Figure 3] This is a cross-sectional view illustrating the lift-up mechanism using an elastic ring. [Figure 4] This is a cross-sectional view illustrating a component fastening structure according to another example of this embodiment. [Modes for carrying out the invention]

[0011] A component fastening structure according to an embodiment is described below with reference to the drawings. The shapes, materials, quantities, and numerical values ​​described below are illustrative examples for illustrative purposes and can be appropriately changed according to the specifications of the component fastening structure. In addition, the same reference numerals are used for equivalent elements in all drawings below.

[0012] Figure 1 illustrates a component fastening structure according to this embodiment. This component fastening structure is included, for example, as part of a vehicle component.

[0013] In this component fastening structure, the components to be fastened include a CFRP component 20, a GFRP component 30, and a metal component 50. Furthermore, the component fastening structure according to this embodiment includes a bolt 10, a collar 60, and an elastic ring 40 as fastening components. As will be described later, the CFRP component 20 and the GFRP component 30 are fastened to the metal component 50 by screwing the bolt 10 into the second fastening hole 52.

[0014] The CFRP part 20 is a resin part molded by impregnating carbon fibers with a resin binder. The GFRP part 30 is a resin part molded by impregnating glass fibers with a resin binder. In Figures 1-4, the CFRP part 20 and the GFRP part 30 are shown as resin parts, but either one of the parts may be the part to be fastened. In other words, the part fastening structure according to this embodiment may be a two-layer structure in which either the CFRP part 20 or the GFRP part 30 is fastened to the metal part 50.

[0015] For the CFRP part 20 and the GFRP part 30, at least the peripheral areas of the first fastening hole 22 and the third fastening hole 32 are plate-like. The CFRP part 20 and the GFRP part 30 are stacked when fastened together.

[0016] A first fastening hole 22 is drilled in the CFRP part 20 along its thickness direction. Similarly, a third fastening hole 32 is drilled in the GFRP part 30 along its thickness direction. Both the first fastening hole 22 and the third fastening hole 32 may be through holes with a circular cross-section. When fastening, the first fastening hole 22 and the third fastening hole 32 are aligned.

[0017] The diameter R2 (hole diameter) of the first fastening hole 22 and the diameter R5 (hole diameter) of the third fastening hole 32 may be equal. Note that "equal diameters" means that even if there is an error between diameters R2 and R5 within the tolerance set during drilling, the diameters are considered equal.

[0018] A support recess 34 is formed on the lower surface 36 of the GFRP part 30, which faces the upper surface 56 of the metal part 50. The support recess 34 is a circular recess in cross-section that is coaxial with the third fastening hole 32. The elastic ring 40 is housed in this support recess 34.

[0019] As described later, when creep occurs in the CFRP component 20, the elastic body ring 40 is crushed against the cylindrical portion 64 of the collar 60. As a result, the elastic body ring 40 bulges radially outward. By housing the elastic body ring 40 in the support depression 34, the bulging of the elastic body ring 40 radially outward from the support depression 34 is suppressed. Thereby, the lift-up effect described later is obtained.

[0020] The metal component 50 is, for example, a component with a larger wall thickness than the CFRP component 20 and the GFRP component 30. The metal component 50 may be, for example, an aluminum plate.

[0021] A second fastening hole 52 is drilled in the metal component 50 in its thickness direction. The second fastening hole 52 is, for example, a blind hole with a circular cross section. Also, for example, an internal thread 54 is cut on the inner peripheral surface of the second fastening hole 52.

[0022] The diameter R7 of the second fastening hole 52 is smaller than the diameters R2 and R5 of the first fastening hole 22 and the third fastening hole 32. Since the internal thread 54 is cut in the second fastening hole 52, the diameter of the thread groove or the effective diameter of the internal thread 54 corresponds to the diameter R7 of the second fastening hole 52. When fastening the CFRP component 20 and the GFRP component 30 to the metal component 50, these three components are stacked. And the CFRP component 20, the metal component 50, and the GFRP component 30 are aligned so that the first fastening hole 22, the second fastening hole 52, and the third fastening hole 32 are coaxial.

[0023] The collar 60 is made of a metal material such as aluminum, for example. That is, even when a compressive force is input from the bolt 10 to the collar 60, creep in the collar 60 is suppressed.

[0024] The collar 60 comprises a flange 62 and a cylindrical portion 64. An insertion hole 66 is drilled in the collar 60 so as to penetrate the flange 62 and the cylindrical portion 64. As illustrated in Figure 1, when fastened, the insertion hole 66 is coaxial with the first fastening hole 22, the second fastening hole 52, and the third fastening hole 32. The diameter R4 (hole diameter) of the insertion hole 66 is equal to the inner diameter R6 of the elastic ring 40. Even if there is an error between the diameter R4 and the inner diameter R6 within the tolerance set during drilling and molding, the diameter R4 and the inner diameter R6 are considered to be equal.

[0025] As illustrated in Figure 1, the cylindrical portion 64 is connected below the flange 62 along the central axis C1. The axial length T1 of the cylindrical portion 64 is greater than or equal to the sum of the thickness T2 of the CFRP part 20 and the thickness T3 of the GFRP part 30 in the support recess 34 forming region (T1 > T2 + T3).

[0026] The outer diameter R3 of the cylindrical portion 64 is less than or equal to the diameters R2 and R5 of the first fastening hole 22 and the third fastening hole 32. Furthermore, the outer diameter R3 exceeds the diameter R7 of the second fastening hole 52. With this structure, the cylindrical portion 64 is inserted into the first fastening hole 22 and the third fastening hole 32. The axial end 68 of the cylindrical portion 64 abuts against the elastic ring 40.

[0027] The flange 62 is the head of the collar 60 and protrudes radially outward from the cylindrical portion 64. The outer diameter R9 of the flange 62 exceeds the diameter R2 of the first fastening hole 22. Therefore, when the cylindrical portion 64 is inserted into the first fastening hole 22 and the third fastening hole 32, the flange 62 comes into contact with (gets caught on) the CFRP part 20.

[0028] The elastic ring 40 is a ring-shaped component made of an elastic material such as rubber. For example, in a natural state where no compressive force is applied to the elastic ring 40, the thickness of the elastic ring 40 is set to exceed the depth of the support recess 34.

[0029] As described above, the inner diameter R6 of the elastic ring 40 is equal to the diameter R4 of the insertion hole in the collar 60. Also, the outer diameter R8 of the elastic ring 40 exceeds the diameters R2 and R5 of the first fastening hole 22 and the third fastening hole 32. For example, the outer diameter R8 of the elastic ring 40 is equal to the diameter of the support recess 34.

[0030] To ensure that the elastic ring 40 is lifted up as described later, the outer diameter R8 of the elastic ring and the diameter of the support recess 34 are sufficiently larger than the diameters R2 and R5 of the first and third fastening holes 22 and 32, respectively. On the other hand, in order to transmit the fastening force along the central axis C1 direction to the head 12 of the bolt 10, the flange 62 of the collar 60, the CFRP part 20, the GFRP part 30, and the metal part 50, the outer diameter R8 of the elastic ring and the diameter of the support recess 34 are less than the diameter R9 of the flange 62. For example, the outer diameter R8 of the elastic ring and the diameter of the support recess 34 are the sum of the diameter R2 of the first fastening hole 22 and the diameter R9 of the flange 62 divided by 2 (R8 = (R2 + R9) / 2).

[0031] The shaft portion 14 of the bolt 10 is inserted into the elastic ring 40. Furthermore, the elastic ring 40 is seated in the support recess 34. In other words, the elastic ring 40 is sandwiched between the CFRP part 20, the GFRP part 30, and the collar 60 and the metal part 50. In particular, as illustrated in Figure 1, the radially inner portion of the elastic ring 40 abuts against the axial end 68 of the cylindrical portion 64 of the collar 60.

[0032] The bolt 10 comprises a head 12 and a shaft 14. The diameter R1 of the shaft 14 is set to be less than or equal to the diameter R4 of the insertion hole 66. A male thread 16 is cut into the axial lower end of the shaft 14. The shaft 14 of the bolt 10 is inserted into the insertion hole 66 and the second fastening hole 52, and the male thread 16 and female thread 54 are then screwed together. By applying a tightening torque to the bolt 10, a tensile force is applied to the bolt 10. This tensile force stretches (elastically deforms) the shaft 14. Compressive forces are also applied to the collar 60, the CFRP part 20, the GFRP part 30, and the metal part 50. This compressive force fastens the CFRP part 20 and the GFRP part 30 to the metal part 50.

[0033] Figure 2 shows an example of creep occurring in the CFRP part 20. As shown in Figure 2 as the amount of thinning L1, the portion of the CFRP part 20 that contacts the flange 62 is subjected to a compressive force for a long period of time, causing the contact portion to thin. The shaft portion 14 of the bolt 10 is stretched in the direction of the central axis C1 due to the input of a tensile force, but it shrinks as the CFRP part 20 thins.

[0034] As the shaft portion 14 contracts, the collar 60 is pushed toward the metal part 50 along the central axis C1. At this time, the axial end 68 of the cylindrical portion 64 of the collar 60 crushes the radially inner portion of the elastic ring 40.

[0035] Referring to Figure 3, the radially inner portion of the elastic ring 40 bulges radially outward as it is crushed by the cylindrical portion 64 of the collar 60. This bulge lifts the GFRP part 30 towards the head 12 of the bolt 10. Furthermore, the CFRP part 20 on top of the GFRP part 30 is also lifted. As a result, the collar 60 is also lifted, and the shaft portion 14 of the bolt 10 is stretched. For example, Figure 3 shows the amount of stretching L11 of the shaft portion 14 due to the bulging of the elastic ring 40. Referring to Figures 2 and 3, for example, the amount of stretching L11 of the shaft portion 14 is less than the amount of thinning L1 of the CFRP part 20 (L11 < L1).

[0036] Thus, in the component fastening structure according to this embodiment, when creep occurs in the CFRP component 20, which is a resin component, the elastic ring 40 performs a lift-up. This suppresses a decrease in the fastening force by the bolt 10.

[0037] <Another example of a component fastening structure> Figure 4 shows another example of the component fastening structure according to this embodiment. In this example, a wedge component 140 is used instead of the elastic ring 40. The wedge component 140 has a shape obtained by dividing the ring into multiple parts in a plan view (view along the C1 axis). For example, the wedge component 140 is divided into 90° units in a plan view, and a total of four are arranged in a ring shape. The wedge component 140 is made of a metal material such as aluminum.

[0038] The wedge component 140 has a triangular cross-section, and the inclined surface 141 closest to the central axis C1 slopes downwards, becoming more downward-sloping towards the second fastening hole 52 as it approaches the central axis C1. The axial end 68A of the cylindrical portion 64 abuts against this inclined surface 141. The axial end 68A may be a complementary inclined surface to the inclined surface 141. For example, the axial end 68A is a slope parallel to the inclined surface 141.

[0039] Furthermore, the inclined surface 142 of the wedge component 140, away from the central axis C1, slopes upward as it approaches the central axis C1, towards the head 12. The lower surface 36 of the support recess 34 abuts against this inclined surface 142. The lower surface 36 may be a slope complementary to the inclined surface 142. For example, the lower surface 36 is a slope parallel to the inclined surface 142.

[0040] The shaft portion 14 of the bolt 10 is inserted into the center of a plurality of wedge parts 140 arranged in a ring shape. As illustrated in Figure 4, the wedge parts 140 are sandwiched between the axial end 68A of the collar 60 and the GFRP part 30 and the metal part 50.

[0041] When creep occurs in the CFRP part 20, which is a resin part, the CFRP part 20 thins. In response, the shaft portion 14 of the bolt 10 shrinks. Consequently, the collar 60 is pushed toward the metal part 50.

[0042] As the collar 60 moves, the wedge component 140 is pushed radially outward. At this time, the inclined surface 142 moves radially outward, lifting the GFRP component 30. Furthermore, the CFRP component 20, the collar 60, and the head 12 of the bolt 10 are lifted. As a result, the amount of shrinkage of the shaft portion 14 of the bolt 10 is suppressed to less than the amount of thinning of the CFRP component 20. [Explanation of symbols]

[0043] 10 bolts, 20 CFRP parts (resin parts), 22 first fastening holes, 30 GFRP parts (resin parts), 32 third fastening holes, 40 elastic ring, 50 metal parts, 52 second fastening holes, 60 collar, 66 insertion hole, 68 axial end of collar.

Claims

[Claim 1] A resin part with a first fastening hole drilled in it, A second fastening hole is drilled, which is axially aligned with the first fastening hole and has a smaller diameter than the first fastening hole, and the metal part is stacked with the resin part. A collar is provided, having an insertion hole drilled coaxially with the first and second fastening holes, with an outer diameter less than or equal to the diameter of the first fastening hole and exceeding the diameter of the second fastening hole, and being inserted into the first fastening hole. A bolt is inserted into the insertion hole and the second fastening hole to fasten the resin part to the metal part, The bolt is inserted, and its outer diameter exceeds the diameter of the first fastening hole. An elastic ring is sandwiched between the axial end of the collar and the resin part and the metal part. A component fastening structure that includes the following features.

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