Press-fit structure, press-fit member, and press-fitted member

Abstract

Provided are a press-fit structure, a press-fit member, and a press-fitted member which are excellent in terms of manufacturability and are capable of obtaining a larger pull-out load.　In this press-fit structure, a resin outer cylinder 2 that is made of a synthetic resin, has a cylindrical shape and is elastically deformable is press-fitted into a press-fit hole 1A. The press-fit structure is characterized in that the press-fit hole 1A comprises: a small diameter portion 1B in which a portion having a constant inner diameter D1 smaller than an outer diameter D2 of the resin outer cylinder 2 is continuous in a press-fitting direction; and an enlarged diameter portion 1C which is provided on the rear side of the small diameter portion 1B in the press-fitting direction so as to be connected to the small diameter portion 1B, and gradually increases in diameter toward the rear side.

Description

Press-fitting structure, press-fitting member, and press-fitted member

[0001] The present invention relates to a press-fitting structure, a press-fitting member, and a press-fitted member.

[0002] Generally, as a press-fitting structure for press-fitting a press-fitting member into a press-fitted member, the press-fitted member has a press-fitted hole in which a portion having the same inner diameter is continuous in the press-fitting direction, and the press-fitting member has an outer peripheral portion having an outer diameter slightly larger than the inner diameter of the press-fitted hole is press-fitted into the press-fitted hole. In such a press-fitting structure, a pull-out load is generated by the frictional force between the inner peripheral surface of the press-fitted hole and the outer peripheral surface of the press-fitting member.

[0003] Further, for example, Patent Document 1 discloses a press-fitting structure in which a rigid outer cylinder portion is press-fitted into a cylindrical holder in a bush-shaped vibration isolator rubber used as a body mount cushion. In this press-fitting structure, when the rigid outer cylinder portion is press-fitted into the cylindrical holder, the rigid outer cylinder portion protrudes to the front side of the cylindrical holder, and an engaging claw portion formed at the protruding tip portion of the rigid outer cylinder portion is engaged with an engaging receiving portion of the cylindrical holder to prevent the rigid outer cylinder portion from coming out of the cylindrical holder.

[0004] Japanese Patent Laid-Open No. 7-4458

[0005] However, when a pull-out load is generated by the frictional force between the inner peripheral surface of the press-fitting hole and the outer peripheral surface of the press-fitting member as described above, in order to generate a larger pull-out load, if the press-fitting allowance is increased, the press-fitting force during press-fitting increases and the productivity deteriorates, and if the allowance is decreased, the press-fitting member is likely to come out. Further, when the engaging claw portion is engaged with the engaging receiving portion of the cylindrical holder to prevent coming out, a gap is generated between the engaging claw portion and the engaging receiving portion, so that rattling occurs due to the generated gap and it is difficult to obtain stable performance.

[0006] Therefore, an object of the present invention is to provide a press-fitting structure, a press-fitting member, and a press-fitted member that are excellent in productivity and can obtain a larger pull-out load.

[0007] To achieve the above objective, the present invention is characterized in that a cylindrical, elastically deformable press-fit member made of synthetic resin is press-fitted into a press-fit hole, and the press-fit hole has a small-diameter portion in which a portion with the same inner diameter smaller than the outer diameter of the press-fit member is continuous in the press-fit direction, and an expanding-diameter portion which is provided connected to the back of the small-diameter portion in the press-fit direction and gradually expands in diameter toward the back.

[0008] According to the present invention, it is possible to provide a press-fit structure, a press-fit member, and a member to be press-fitted that offer excellent manufacturability and high pull-out load. Other problems, configurations, and effects will be clarified by the following description of embodiments.

[0009] This is a perspective view of a press-fit structure forming a press-fit structure according to an embodiment of the present invention, viewed from the flange side. This is a perspective view of a press-fit structure forming a press-fit structure according to an embodiment of the present invention, viewed from the opposite side of the flange. This is a cross-sectional view showing the holder and resin outer cylinder cut in the press-fit direction. This is a cross-sectional view showing the press-fit structure cut in the press-fit direction.

[0010] Hereinafter, an embodiment of the press-fit structure, press-fit member, and press-fit member according to the present invention will be described with reference to the drawings. The press-fit structure according to this embodiment is used, for example, as a body mount for fixing the vehicle body to a frame, and as shown in Figures 1 and 2, it is a press-fit structure in which a resin outer cylinder 2 is press-fitted into a holder 1 which forms part of a member frame. Hereinafter, a press-fit structure 3 composed of a holder 1 as the press-fit member and a resin outer cylinder 2 as the press-fit member will be described as an example.

[0011] The holder 1 is made of aluminum or iron and, as shown in Figure 3, has a cylindrical shape that surrounds the press-fit hole 1A into which the resin outer cylinder 2 is press-fitted. The resin outer cylinder 2 is inserted into the holder 1 from the front side (upper side in Figure 2) to the back side (lower side in Figure 2) in the press-fitting direction of the press-fit hole 1A which penetrates through it, and then press-fitted.

[0012] The holder 1 is provided with a press-fit hole 1A having a small-diameter portion 1B that is continuous in the press-fit direction (predetermined direction) with the same inner diameter D1, and an enlarged diameter portion 1C that is connected to the small-diameter portion 1B on the far side (one side) of the small-diameter portion 1B in the press-fit direction, and whose inner diameter gradually expands toward the far side in the press-fit direction. The holder 1 also has a curved portion 1D on the near side of the small-diameter portion 1B in the press-fit direction, which curves so that its inner diameter expands toward the near side in the press-fit direction.

[0013] The resin outer cylinder 2 is made of an elastically deformable synthetic resin and has an outer cylinder portion 2A which is cylindrical in shape with a portion of the same outer diameter D2 that is continuous in the press-fitting direction and penetrates in the press-fitting direction, and a flange portion 2B which is provided on the front edge of the outer cylinder portion 2A and protrudes in the expanding diameter direction to form an annular shape. The outer diameter D2 of the outer cylinder portion 2A is formed to be larger than the inner diameter D1 of the small diameter portion 1B of the holder 1, and is also larger than the maximum inner diameter D3 of the expanded diameter portion 1C. Furthermore, the outer diameter D2 of the outer cylinder portion 2A is formed to be slightly smaller than the maximum inner diameter D4 of the curved portion 1D.

[0014] When press-fitting the resin outer cylinder 2 into the press-fit hole 1A of the holder 1, the tip side of the resin outer cylinder 2 that does not have a flange portion 2B is inserted from the front side in the press-fitting direction of the holder 1. At this time, the tip 2C of the resin outer cylinder 2 is guided by the curved portion 1D of the holder 1, and the resin outer cylinder 2 enters the small diameter portion 1B while elastically deforming to reduce its diameter.

[0015] Subsequently, as the resin outer cylinder 2 is further inserted into the press-fit hole 1A, the reduced diameter resin outer cylinder 2 slides along the press-fit hole 1A as its outer surface slides into the back of the small-diameter portion 1B.

[0016] Then, when the tip 2C of the resin outer cylinder 2 enters the enlarged diameter portion 1C, the portion of the resin outer cylinder 2 that has entered the enlarged diameter portion 1C slides along the inner circumferential surface of the enlarged diameter portion 1C and moves further into the enlarged diameter portion 1C. Subsequently, as shown in Figure 4, the flange portion 2B of the resin outer cylinder 2 comes into contact with the front end 1E of the holder 1, and the resin outer cylinder 2 is pressed into the holder 1.

[0017] At this time, the portion of the resin outer cylinder 2 that enters the enlarged diameter portion 1C is gradually relieved of its reduced diameter state, so the frictional force when the outer cylinder portion 2A slides in the enlarged diameter portion 1C is smaller than the frictional force when it slides in the small diameter portion 1B. For this reason, the pressing force when pressing the resin outer cylinder 2 into the holder 1 is smaller when the enlarged diameter portion 1C is provided than when the press-fit hole 1A is formed with the same inner diameter along its entire length.

[0018] When the resin outer cylinder 2 is press-fitted into the holder 1, the portion of the resin outer cylinder 2 that is reduced in diameter by the small diameter portion 1B presses the inner surface of the small diameter portion 1B toward the outer surface, and the portion that is reduced in diameter by the enlarged diameter portion 1C presses the inner surface of the enlarged diameter portion 1C toward the outer surface. Therefore, when a force is applied in the direction that causes the resin outer cylinder 2 to come out of the holder 1, that is, toward the front in the press-fitting direction, the frictional force generated between the outer surface of the resin outer cylinder 2 and the inner surface of the small diameter portion 1B, and the frictional force acting in the press-fitting direction along the enlarged diameter portion 1C that is generated between the outer surface of the resin outer cylinder 2 and the inner surface of the enlarged diameter portion 1C, press against the inner surface of the enlarged diameter portion 1C, thereby increasing the force that causes the resin outer cylinder 2 to come out and making it difficult to remove.

[0019] In this press-fit structure, a synthetic resin outer cylinder 2, which is cylindrical in shape with an outer diameter D2 larger than the small diameter portion 1B and is elastically deformable, is press-fitted into a press-fit hole 1A formed in the holder 1, which has a small diameter portion 1B in which a portion of the same inner diameter D1 is continuous in the press-fit direction, and an enlarged diameter portion 1C that is connected to the small diameter portion 1B on the back side of the small diameter portion 1B in the press-fit direction and gradually increases in diameter toward the back. Therefore, the press-fit force during press-fitting can be reduced compared to when a press-fit member is press-fitted into a press-fit hole that only has a continuous portion of the same inner diameter, and since the resin outer cylinder 2 presses against both the small diameter portion 1B and the enlarged diameter portion 1C, it is possible to obtain a higher pull-out load. As a result, it is possible to obtain a high pull-out load while maintaining excellent manufacturability.

[0020] Furthermore, since the outer diameter D2 of the resin outer cylinder 2 is larger than the maximum inner diameter D3 of the enlarged diameter section 1C, the resin outer cylinder 2 can press against the inner circumferential surface of the enlarged diameter section 1C all the way to the inner end. As a result, a pull-out force can be generated throughout the entire area of ​​the enlarged diameter section 1C, making it possible to obtain a larger pull-out load.

[0021] Furthermore, the inventors of this invention conducted tests on the pressing force and release force using an aluminum collar having an enlarged diameter portion as the press-fit member and a resin outer cylinder as the press-fit member, and confirmed the following results.

[0022] <Relationship between the shape of the enlarged section and the pressing force> - The smaller the tip constriction ratio (larger inclination angle) of the enlarged section, the lower the pressing force. - The longer the length of the enlarged section in the pressing direction, the lower the pressing force.

[0023] <Relationship between the length of the enlarged section in the press-fit direction and the room-temperature release force> ・Without an enlarged section, "release force (initial value) = release force (maximum value)," and after the initial release, the release force decreases monotonically as the engagement length decreases with increasing displacement (=release amount). ・With an enlarged section, in addition to the same effect of reducing release force as without an enlarged section, there is an effect of increasing release force as the outer diameter of the outer cylinder narrows in the enlarged section with the release amount. Therefore, the maximum release force is reached when the effect of reducing release force and the effect of increasing release force are balanced. ・The longer the enlarged section in the press-fit direction, the smaller the release force (initial value).

[0024] <Relationship between the length of the enlarged diameter section in the press-fit direction and the release force after thermal aging> - In the case of no enlarged diameter section, the release force decreases monotonically, similar to the case at room temperature. - In the case of an enlarged diameter section, the release force reaches its maximum value under conditions where the effect of decreasing the release force and the effect of increasing the release force are balanced, similar to the case at room temperature, but the length of the enlarged diameter section in the press-fit direction is longer than at room temperature. - The longer the length of the enlarged diameter section in the press-fit direction, the smaller the difference between the press-fit force and the release force. - The longer the length of the enlarged diameter section in the press-fit direction, the smaller the release force (initial value).

[0025] <Relationship between the maximum inner diameter of the enlarged section and the release force at room temperature> - The larger the maximum inner diameter of the enlarged section, the smaller the release force (initial value). - Regardless of the tip constriction diameter, the release force (maximum value) is equivalent to that without the enlarged section. - The larger the tip diameter, the smaller the press-fit-release force.

[0026] <Relationship between the maximum inner diameter of the enlarged section and the pull-out force after thermal aging> - The initial value of the pull-out force is the same regardless of the maximum inner diameter of the enlarged section. - The larger the maximum inner diameter of the enlarged section, the greater the maximum value of the pull-out force.

[0027] One embodiment of the present invention has been described above. It should be noted that the present invention is not limited to the above-described embodiment and includes various other modifications. For example, the above-described embodiment is described in detail for the purpose of clearly illustrating the present invention and is not necessarily limited to having all the described configurations. Furthermore, it is possible to replace some of the configurations of this embodiment with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of this embodiment. Moreover, it is possible to add, delete, or replace some of the configurations of this embodiment with those of other embodiments.

[0028] In the above embodiment, an example was described in which the press-fit structure of the present invention is used in a body mount for fixing the vehicle body to the frame. However, it is not limited to this, and may also be used in press-fit parts of engine mounts, motor mounts, bushings, strut mounts, cab mounts, subframe mounts, spring seats, air springs, and industrial vibration damping materials.

[0029] 1: Holder 1A: Hole to be pressed in 1B: Small diameter section 1C: Enlarged diameter section 1D: Curved section 1E: Front end of the holder 2: Resin outer cylinder 2A: Outer cylinder section 2B: Flange section 2C: Tip of the resin outer cylinder 3: Press-fit structure D1: Inner diameter of the small diameter section D2: Outer diameter of the outer cylinder section D3: Maximum inner diameter of the enlarged diameter section D4: Maximum inner diameter of the curved section

Claims

1. A press-fit structure in which a cylindrical, elastically deformable press-fit member made of synthetic resin is press-fitted into a press-fit hole, wherein the press-fit hole has a small-diameter portion having the same inner diameter smaller than the outer diameter of the press-fit member and continuous in the press-fit direction, and an enlarged-diameter portion provided behind the small-diameter portion in the press-fit direction and connected to the small-diameter portion, and gradually expanding in diameter toward the back.

2. The press-fit structure according to claim 1, characterized in that the outer diameter of the press-fit member is greater than the maximum inner diameter of the enlarged portion.

3. A press-fit member characterized by being pressed into a press-fit hole toward one side, having a cylindrical shape with an outer diameter larger than the inner diameter of the press-fit hole, and made of an elastically deformable synthetic resin, having a small-diameter portion in which portions of the same inner diameter are continuous in a predetermined direction, and an expanding-diameter portion provided on one side of the small-diameter portion in the predetermined direction and connected to the small-diameter portion, and gradually expanding toward the one side, wherein the press-fit member is formed toward the one side, and has an outer diameter larger than the inner diameter of the press-fit hole.

4. A press-fit member having a press-fit hole into which a cylindrical, elastically deformable press-fit member made of synthetic resin is press-fitted, wherein the press-fit hole comprises a small-diameter portion having an inner diameter smaller than the outer diameter of the press-fit member and continuous in the press-fit direction, and an enlarged-diameter portion provided behind the small-diameter portion in the press-fit direction and connected to the small-diameter portion, and gradually expanding in diameter toward the back.

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