Screw-fastening structure and vehicle component

Abstract

To provide a screw-fastening structure which can maintain fastening force of the screw for a long period.SOLUTION: A screw-fastening structure fastens at least a first member 5 and a second member 4 using a screw S. The first member 5 has a boss 11 projecting toward the second member 4 and a screw hole 12 in which the screw S is screwed at a tip of the boss 11. The second member 4 has a through hole 21 passed through the boss 11, a cylindrical section 22 projecting over the whole circumference from the surrounding of the through hole 21, and a plurality of projection sections 23 which are arranged side by side in a circumferential direction on a tip side of the cylindrical section 22 and project more than the tip of the boss 11 passed through the through hole 21. When the screw S is screwed to the screw hole 12 and a head of the screw S is abutted on the tip of the boss 11, the head of the screw S is fastened in a state of crushing tip sides of the plurality of projection sections 23.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a screw fastening structure and vehicle parts.

Background Art

[0002] For example, a vehicle lamp mounted on a vehicle has a structure in which vehicle parts such as a light source, an inner lens, a reflector, and an extension are arranged inside a lamp body composed of a housing with an open front surface and a cover lens (outer lens) that covers the opening of the housing.

[0003] By the way, when attaching the above-described vehicle parts inside the lamp body, fixing means such as screws are required. Further, one member and the other member constituting the vehicle parts are fixed by screwing.

[0004] However, in the screw fastening structure, over time, the fastening force of the screw may decrease, and play may occur between one member and the other member. For this reason, efforts have been made to increase the fastening force of the screw (see, for example, Patent Documents 1 and 2 below).

[0005] For example, Patent Document 1 below discloses a vehicle lamp in which a lamp unit having a light source is disposed inside a lamp outer casing composed of a lamp housing having an opening at least on one side and a cover that covers the opening of the lamp housing. The lamp unit includes a base body, a first optical body, and a second optical body. The first optical body and the second optical body are each provided with a screwing portion that is fixed to the base body by screws. The first optical body and the second optical body are attached to the base body by co-tightening using screws in a state where the screwing portions are overlapped. The first optical body is provided with a crushing protrusion that is crushed by a pressing force applied from the second optical body during co-tightening. The first optical body is provided with a contact portion that is pressed against the base body during co-tightening. The second optical body is provided with a contact portion that is pressed against the base body in a state where the crushing protrusion is crushed during co-tightening.

[0006] On the other hand, Patent Document 2 below describes a configuration in which a plurality of convex portions are provided around a threaded hole, and when a screw is screwed into a screw receiving portion through which the screw is inserted, the plurality of convex portions come into contact with the head of the screw and are crushed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] By the way, in the conventional screw fastening structure described above, the fastening force of the screw immediately after fastening can be increased by crushing (pressing) the protrusion (convex portion). On the other hand, since the entire protrusion (convex portion) is crushed, the elastic modulus of the protrusion (convex portion) is lost due to the plastic deformation of the protrusion (convex portion), and the repulsive force is lost. For this reason, there is a concern that the fastening force of the screw decreases with the passage of time and rattling occurs due to the occurrence of high-temperature and low-temperature cycles or creep (stress relaxation).

[0009] The present invention has been proposed in view of such conventional circumstances, and an object thereof is to provide a screw fastening structure capable of maintaining the fastening force of a screw over a long period of time, and a vehicle component having such a fastening structure.

Means for Solving the Problems

[0010] In order to achieve the above object, the present invention provides the following means. 〔1〕 A screw fastening structure for fastening at least a first member and a second member using a screw, The first member has a boss protruding toward the second member and a screw hole into which the screw is screwed at the tip of the boss, The second member has a through hole that penetrates the boss, a cylindrical portion that protrudes over the entire circumference from around the through hole, and a plurality of protrusions that are arranged side by side in the circumferential direction on the tip side of the cylindrical portion and protrude more than the tip of the boss that penetrates the through hole. A screw fastening structure, characterized in that when the screw is screwed into the screw hole and the head of the screw abuts against the tip of the boss, the head of the screw is fastened in a state where the tip sides of the plurality of protrusions are crushed. 〔2〕 The screw fastening structure according to 〔1〕 above, characterized in that at least the tip side of the protrusion is plastically deformed and the cylindrical portion is elastically deformed when the screw is fastened. 〔3〕 The screw fastening structure according to 〔1〕 above, characterized in that the plurality of protrusions are arranged at intervals in the circumferential direction of the cylindrical portion. 〔4〕 The screw fastening structure according to 〔1〕 above, characterized in that the protrusion has a shape that tapers toward the tip. 〔5〕 The screw fastening structure according to 〔4〕 above, characterized in that the protrusion has a tip surface that abuts against the head of the screw and a pair of inclined surfaces that are inclined from both sides of the tip surface toward the tip of the cylindrical portion. 〔6〕 The screw fastening structure according to 〔1〕 above, characterized in that three of the plurality of protrusions are arranged side by side in the circumferential direction of the cylindrical portion. 〔7〕 The screw fastening structure according to 〔1〕 above, characterized in that the first member is made of a material having a higher yield point than the second member. 〔8〕 The first member is made of a metal material, The screw fastening structure according to 〔7〕 above, characterized in that the second member is made of a resin material. 〔9〕 A vehicle part including the screw fastening structure according to any one of 〔1〕 to 〔8〕 above.

Advantages of the Invention

[0011] As described above, according to the present invention, there is provided a screw fastening structure capable of maintaining the fastening force of the screw over a long period of time, and a vehicle part including such a fastening structure.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make each component easy to see, the dimensional scales may be made different depending on the components, and the dimensional ratios of each component are not necessarily the same as the actual ones.

[0014] As an embodiment of the present invention, for example, the screw fastening structure provided in the vehicle part 1 shown in FIGS. 1 to 3 will be described.

[0015] Note that FIG. 1 is a perspective view showing the vehicle part 1. FIG. 2 is a perspective view showing the state before fastening the screw S in the screw fastening structure provided in the vehicle part 1. FIG. 3 is a side view showing the state where the screw S is fastened in the screw fastening structure.

[0016] Also, in the drawings shown below, an XYZ orthogonal coordinate system is set, and the X-axis direction is the front-rear direction (length direction) of the vehicle part 1, the Y-axis direction is the left-right direction (width direction) of the vehicle part 1, and the Z-axis direction is the up-down direction (height direction) of the vehicle part 1, and each is shown accordingly.

[0017] As shown in FIG. 1, the vehicle part 1 of the present embodiment applies the screw fastening structure of the present invention to a lamp unit that irradiates light toward the front of the vehicle.

[0018] Specifically, this vehicle part 1 includes a circuit board 2 with a light source (not shown) mounted on the front side, a lens 3 disposed on the front side of the light source, a lens holder 4 for holding the lens 3, and a heat sink 5 attached to the back side of the circuit board 2.

[0019] The screw fastening structure of this embodiment is a structure in which the heat sink 5, which is the first member, and the lens holder 4, which is the second member, are fastened using a plurality (three in this embodiment) of screws S.

[0020] In this embodiment, the lens holder 4 is made of a resin material such as polycarbonate. On the other hand, the heat sink 5 is made of a metal material such as aluminum.

[0021] Note that the screw fastening structure of this embodiment is provided at three locations: the lower left and right corner portions and the upper central portion of the lens holder 4. Since these three locations basically have the same structure, the screw fastening structure located at the upper central portion will be described while showing it in FIGS. 2 and 3.

[0022] In the screw fastening structure of this embodiment, as shown in FIGS. 2 and 3, the heat sink 5 has a boss 11 that protrudes toward the lens holder 4 and a screw hole 12 into which the screw S is screwed at the tip of the boss 11.

[0023] The boss 11 protrudes cylindrically from the front side of the heat sink 5, and its tip forms a flat surface (hereinafter referred to as the "seating surface") 11a.

[0024] The screw hole 12 forms a female screw portion by being drilled in the depth direction from the central portion of the seating surface 11a.

[0025] On the other hand, the lens holder 4 has a through hole 21 for passing through the boss 11, a cylindrical portion 22 protruding over the entire circumference from the periphery of the through hole 21, and a plurality (three in this embodiment) of protrusion portions 23 arranged side by side in the circumferential direction on the tip side of the cylindrical portion 22.

[0026] The through-hole 21 is constituted by a circular hole portion that penetrates in the thickness direction through a mounting piece 4a protruding from around the lens holder 4.

[0027] The cylindrical portion 22 is provided so as to protrude substantially cylindrically from around the through-hole 21 toward the front side. Further, the outer peripheral surface of the cylindrical portion 22 forms an inclined surface whose diameter gradually decreases toward the tip side. Thereby, the thickness of the cylindrical portion 22 is larger on the base end side than on the tip side.

[0028] The plurality of protrusion portions 23 are arranged side by side at regular intervals in the circumferential direction of the cylindrical portion 22. In the present embodiment, three protrusion portions 23 are arranged substantially equidistantly in the circumferential direction of the cylindrical portion 22. Further, the tip of the cylindrical portion 22 forms a flat surface (hereinafter referred to as the "tip surface") 22a between adjacent protrusion portions 23.

[0029] Each protrusion portion 23 is provided so as to protrude beyond the tip (seating surface 11a) of the boss 11 that penetrates the through-hole 21 from the tip side of the cylindrical portion 22. Further, each protrusion portion 23 has a shape that tapers toward its tip. Specifically, each protrusion portion 23 has a tip surface 23a that abuts against the head of the screw S when the screw S is tightened, and a pair of inclined surfaces 23b that incline from both sides of the tip surface 23a toward the tip of the cylindrical portion 22.

[0030] The tip surface 23a is constituted by a flat surface or a curved surface that is convexly curved. The pair of inclined surfaces 23b are inclined in opposite directions so as to be continuously connected to the tip surface 22a of the cylindrical portion 22.

[0031] Note that the protrusion portion 23 is not limited to such a shape, and for example, the width of the tip surface 23a, the width and angle (gradient) of the inclined surface 23b, etc. can be appropriately changed. Also, the number and arrangement of the protrusion portions 23 can be appropriately changed.

[0032] In the screw fastening structure of the present embodiment having the above configuration, as shown in FIG. 3, first, with the boss 11 penetrating the through hole 21, the lens holder 4 and the heat sink 5 are abutted against each other.

[0033] At this time, each protruding portion 23 protrudes by a predetermined height dimension t from the seating surface 11a of the boss 11. This height dimension t is preferably about 0.1 to 0.3 (0.2 ± 0.1) mm, for example.

[0034] Next, from this state, the male screw portion of the screw S is screwed into the screw hole 12. Further, when the head of the screw S abuts (seats) against the seating surface 11a of the boss 11, the head of the screw S is fastened in a state where the tip sides of the plurality of protruding portions 23 are crushed by the height dimension t.

[0035] At this time, at least the tip sides of the respective protruding portions 23 are plastically deformed, and the cylindrical portion 22 is elastically deformed. Further, a state is obtained in which stress is dispersed from each protruding portion 23 toward the cylindrical portion 22.

[0036] Thus, in the screw fastening structure of the present embodiment, when the screw S is fastened as described above, the head of the screw S that abuts (seats) against the seating surface 11a of the boss 11 crushes the tip sides of the plurality of protruding portions 23. Therefore, the lens holder 4 is firmly pressed against the heat sink 5 by the head of the screw S via the plurality of protruding portions 23.

[0037] Also, when the screw S is fastened as described above, the cylindrical portion 22 is elastically deformed, so that an elastic force (repulsive force) is generated in the axial direction of the screw S, and the tip sides of the respective protruding portions 23 are strongly pressed against the head of the screw S.

[0038] Furthermore, in the screw fastening structure of the present embodiment, since the three protruding portions 23 described above are arranged substantially equidistantly in the circumferential direction of the cylindrical portion 22, it is possible to evenly press the tip sides of the respective protruding portions 23 against the head of the screw S.

[0039] As described above, in the screw fastening structure of the present embodiment, it is possible to maintain the fastening force of the screw S over a long period of time. Therefore, in the vehicle component 1 provided with the screw fastening structure of the present embodiment, it is possible to prevent the fastening force of the screw S from decreasing over time due to the occurrence of the above-described high-temperature and low-temperature cycles or creep, etc., and rattling from occurring between the lens holder 4 and the heat sink 5.

[0040] Note that the present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0041] For example, in the above-described embodiment, a structure in which the heat sink 5, which is the above-described first member, and the lens holder 4, which is the second member, are fastened using a plurality of screws S is illustrated. However, when the first member and the second member constituting the vehicle component are fixed by screw fastening, the fastening structure of the present invention can be widely applied. Also, when the vehicle component is attached inside the lamp body, the screw fastening structure of the present invention can be widely applied.

[0042] Further, in the screw fastening structure to which the present invention is applied, the fastening may be performed with another member sandwiched between the first member and the second member constituting the vehicle component.

[0043] Also, the first member may be made of a material having a higher yield point than the second member, and may have a configuration made of a resin material having a higher yield point than the second member in addition to the above-described metal material.

Explanation of Reference Numerals

[0044] 1... Vehicle component 4... Lens holder (second member) 5... Heat sink (first member) 11... Boss 12... Screw hole 21... Through hole 22... Cylindrical portion 23... Protrusion 23a... Tip surface 23b... Pair of inclined surfaces S... Screw

Claims

1. A screw fastening structure for fastening at least a first member and a second member using a screw, wherein the first member has a boss protruding toward the second member and a screw hole into which the screw is screwed at the tip of the boss, the second member has a through hole penetrating the boss, a cylindrical portion protruding over the entire circumference from around the through hole, and a plurality of protrusions arranged side by side in the circumferential direction on the tip side of the cylindrical portion and protruding beyond the tip of the boss penetrating the through hole, characterized in that when the screw is screwed into the screw hole and the head of the screw abuts against the tip of the boss, the head of the screw is fastened in a state where it crushes the tip side of the plurality of protrusions.

2. The screw fastening structure according to claim 1, characterized in that at least the tip side of the protrusion is plastically deformed and the cylindrical portion is elastically deformed when the screw is fastened.

3. The screw fastening structure according to claim 1, characterized in that the plurality of protrusions are arranged at intervals in the circumferential direction of the cylindrical portion.

4. The screw fastening structure according to claim 1, characterized in that the protrusion has a shape that tapers toward the tip.

5. The screw fastening structure according to claim 4, characterized in that the protrusion has a tip surface that abuts against the head of the screw and a pair of inclined surfaces that incline from both sides of the tip surface toward the tip of the cylindrical portion.

6. The screw fastening structure according to claim 1, characterized in that three of the plurality of protrusions are arranged side by side in the circumferential direction of the cylindrical portion.

7. The screw fastening structure according to claim 1, characterized in that the first member is made of a material having a higher yield point than the second member.

8. The first member is made of a metal material, The screw fastening structure according to claim 7, characterized in that the second member is made of a resin material.

9. A vehicle part comprising the screw fastening structure according to any one of claims 1 to 8.

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