JP7489185B2 - Press-fit collar structure - Google Patents

Description

The present invention relates to a collar press-fit structure.

Patent Document 1 discloses a filter device for an internal combustion engine.
The cyclone pre-separator of the filter device described in Patent Document 1 includes a resin fixing part having a through hole formed therein. A cylindrical metal bush is press-fitted into the through hole. The cyclone pre-separator is fixed to the filter housing by inserting a screw into the bush and screwing the screw into the bush of the filter housing.

JP 2013-507248 A

In the press-fit structure of such a bush (hereinafter referred to as a collar), the inner diameter of the through hole is set smaller than the outer diameter of the collar. Therefore, when the collar is pressed into the through hole, the inner peripheral surface of the through hole is scraped by the edge of the collar, generating shavings, or so-called burrs. If the burrs thus generated protrude from the through hole and become caught between the head of the screw and the end face of the collar, or between the fixing object and the end face of the collar, there is a risk that the fixing part cannot be screwed to the fixing object with the specified tightening torque. This causes problems such as the time required to design and modify the mold for forming the fixing part so as to reduce the amount of burrs, and the need for a separate process to remove the burrs generated during the press-fit process.

The object of the present invention is to provide a collar press-fit structure that can prevent burrs from protruding from the through hole.

The collar press-fit structure for achieving the above object includes a resin fixing part having a through hole formed therein, and a cylindrical collar press-fitted into the through hole. When the front and rear sides of the press-fit direction of the collar into the through hole are defined as the front and rear sides, the inner peripheral surface of the through hole is provided with a contact part that follows the outer peripheral surface of the collar and abuts against the outer peripheral surface, and a pressing part that is provided in a part of the circumferential direction of the through hole and protrudes inward from the contact part when the collar is not pressed-fitted, but presses the outer peripheral surface of the collar when the collar is pressed-fitted. On the inner peripheral surface of the through hole forward of the pressing part, a relief recess that forms a gap with the outer peripheral surface of the collar is provided forward of the pressing part and at a position that overlaps with the pressing part in the radial direction of the through hole.

According to this configuration, the outer peripheral surface of the collar is pressed by the pressing portion provided on the inner peripheral surface of the through hole, and the collar is pressed into the through hole. In addition, the outer peripheral surface of the collar is abutted and supported by the abutment portion provided on the inner peripheral surface of the through hole, suppressing wobbling of the collar. Here, a gap is formed between the outer peripheral surface of the collar and the through hole by the escape recess provided on the inner peripheral surface of the through hole. Therefore, when the collar is pressed into the through hole, burrs generated by the pressing portion protruding inward from the abutment portion being scraped by the edge of the collar are pushed out as the collar is pressed into the through hole and stored in the gap. Therefore, it is possible to suppress burrs from protruding from the through hole.

The present invention can prevent burrs from protruding from the through hole.

13 is a plan view showing a fixing portion in a state where a collar is press-fitted into a through hole in one embodiment of a collar press-fitting structure; FIG. 13 is a bottom view showing the fixing portion with the collar pressed into the through hole. FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. FIG. 13 is a plan view showing the fixing portion in a state where the collar is not press-fitted into the through hole. 13 is a bottom view showing the fixing portion in a state where the collar is not press-fitted into the through hole. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5 . 8 is a cross-sectional view taken along line 8-8 in FIG. 5 . FIG. 11 is a cross-sectional view showing a fixing portion of a modified example.

Hereinafter, one embodiment of a press-fit structure for a collar will be described with reference to FIGS.
1 and 2, the collar press-fit structure includes a resin fixing part 10 having a through hole 20 formed therein, and a cylindrical collar 30 press-fitted into the through hole 20 along the axial direction of the through hole 20. The collar 30 in this embodiment is a metallic collar.

First, the basic configuration of the through hole 20 in the fixing part 10 with the collar 30 pressed into the through hole 20 will be described with reference to Figures 1 to 4. In the following, the front and rear sides of the press-fitting direction A of the collar 30 into the through hole 20 will be simply referred to as the "front side" and the "rear side". In addition, the circumferential direction of the through hole 20 will be simply referred to as the circumferential direction.

As shown in Figures 1 to 4, the inner peripheral surface 21 of the through hole 20 is provided with a plurality of abutment portions 22 that conform to and abut against the outer peripheral surface 31 of the collar 30, and a plurality of pressing portions 23 that press against the outer peripheral surface 31, which are alternately provided in the circumferential direction. In this embodiment, four abutment portions 22 are provided at equal intervals in the circumferential direction. In addition, four pressing portions 23 are provided at equal intervals in the circumferential direction.

As shown in FIGS. 1 and 3 , an escape recess 24 is provided on the inner circumferential surface 21 of the through hole 20 forward of the pressing portion 23 to form a gap S between the inner circumferential surface 31 of the collar 30 .
3, the inner peripheral surface of the relief recess 24 is inclined so that the front side is located closer to the outer peripheral side. Therefore, the distance between the inner peripheral surface of the relief recess 24 and the outer peripheral surface 31 of the collar 30 is larger toward the front side. The relief recess 24 extends to the front end 25 of the through hole 20.

Next, the configuration of the through hole 20 when the collar 30 is not press-fitted will be described with reference to FIGS.
5 and 6, the inner circumferential surfaces of the contact portions 22 are located on the same imaginary circle V. Each pressing portion 23 protrudes inward from each contact portion 22, i.e., from the imaginary circle V. Each pressing portion 23 extends along the tangent direction of the imaginary circle V. In the following description, the pressing portion 23 protruding inward from the contact portion 22 will be distinguished and described as pressing portion 23B. In this embodiment, the volume of the protruding portion of pressing portion 23B is smaller than the volume of the gap S formed by the relief recess 24.

As shown in Figs. 5 and 7, the relief recesses 24 are provided in front of the pressing portion 23B and at a position overlapping the pressing portion 23B in the radial direction of the through hole 20. As shown in Fig. 5, in this embodiment, four relief recesses 24 are provided at positions corresponding to the four pressing portions 23B. Both ends 24a of the relief recesses 24 are located outside both ends 23a of the pressing portion 23B in the circumferential direction.

As shown in FIG. 6, the rear opening 26 of the through hole 20 is provided with a guide surface 26a around its entire periphery, the inner diameter of which decreases toward the front.
As shown in FIGS. 7 and 8, in the through hole 20, a guide surface 26a, a pressing portion 23B, and a relief recess 24 are adjacent to each other in this order from the rear end to the front end.

Next, the operation of this embodiment will be described.
As shown in Fig. 1 and Fig. 3, the collar 30 is pressed into the through hole 20 by pressing the outer peripheral surface 31 of the collar 30 with the pressing portion 23 provided on the inner peripheral surface 21 of the through hole 20. The outer peripheral surface 31 of the collar 30 is abutted against and supported by the abutment portion 22 provided on the inner peripheral surface 21 of the through hole 20, thereby suppressing wobbling of the collar 30. Here, a gap S is formed between the outer peripheral surface 31 of the collar 30 and the through hole 20 by the relief recess 24 provided on the inner peripheral surface 21 of the through hole 20. Therefore, when the collar 30 is pressed into the through hole 20, the pressing portion 23B protruding inward from the abutment portion 22 is scraped by the edge of the collar 30 to become the pressing portion 23, and burrs generated thereby are pushed out as the collar 30 is pressed into the through hole 20 and stored in the gap S.

Next, the effects of this embodiment will be described.
(1) On the inner surface 21 of the through hole 20, a relief recess 24 that forms a gap S with the outer peripheral surface 31 of the collar 30 is provided forward of the pressing portion 23 at a position that overlaps with the pressing portion 23 in the radial direction of the through hole 20.

According to this configuration, the above-mentioned effect is achieved, and therefore, burrs can be prevented from protruding from the through hole 20 .
(2) The multiple pressing portions 23B are provided at intervals from one another in the circumferential direction, and the multiple relief recesses 24 are provided at positions corresponding to the multiple pressing portions 23B, respectively.

With this configuration, since the multiple pressing portions 23B are spaced apart from one another in the circumferential direction, the center of the collar 30 can be easily aligned with the center of the through hole 20. This allows the collar 30 to be easily and stably pressed into the through hole 20. In addition, burrs generated by cutting the multiple pressing portions 23B are stored in multiple gaps S formed between the outer peripheral surface 31 of the collar 30 and multiple escape recesses 24 provided at positions corresponding to the multiple pressing portions 23B. Therefore, the protrusion of burrs from the through hole 20 can be effectively suppressed.

(3) The relief recess 24 extends to the front end 25 of the through hole 20 .
According to this configuration, the volume of the gap S formed between the relief recess 24 and the outer peripheral surface 31 of the collar 30 can be increased, and a large amount of burrs can be accommodated in the gap S.

In addition, with the above configuration, the escape recess 24 extends to the front end of the through hole 20, so the escape recess 24 is less likely to have an undercut shape, and the configuration of the mold for molding the fixed part 10 is simplified. This makes it possible to easily mold the fixed part 10 having the through hole 20.

(4) The circumferential ends 24a of the relief recess 24 are located outwardly of the circumferential ends 23a of the pressing portion 23B.
With this configuration, it is possible to prevent the occurrence of inconvenience such as some of the burrs generated by the cutting of the pressing portion 23B not being accommodated in the gap S formed between the escape recess 24 and the outer peripheral surface 31 of the collar 30.

<Example of change>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

The ends 24a of the relief recess 24 do not have to be located outside the ends 23a of the pressing portion 23B. For example, only one of the ends 24a may be located between the ends 23a of the pressing portion 23B.

The shape of the relief recess 24 is not limited to the one exemplified in this embodiment, and can be, for example, a relief recess 24A that extends to the front end 25 while maintaining a constant distance from the outer peripheral surface 31 of the collar 30, as shown in FIG. 9.

The relief recess 24 is not limited to being provided adjacent to the pressing portion 23B in the press-fitting direction A, and the abutment portion 22 may be provided between the relief recess 24 and the pressing portion 23B in the press-fitting direction A.

- The pressing portion 23B is not limited to being provided adjacent to the guide surface 26a in the press-fitting direction A, and the abutment portion 22 may be provided between the pressing portion 23B and the guide surface 26a in the press-fitting direction A.

The number of the pressing portions 23 and the relief recesses 24 is not limited to four, and the number of these portions can be changed arbitrarily.
A plurality of relief recesses 24 may be provided at positions corresponding to one pressing portion 23. Also, a plurality of pressing portions 23 may be provided at positions corresponding to one relief recess 24.

- The collar 30 is not limited to being made of metal, but may be made of a resin material that is harder than the fixing portion.

Reference Signs List 10: fixing portion 20: through hole 21: inner circumferential surface 22: abutment portion 23, 23B: pressing portion 23a: end 24, 24A: relief recess 24a: end 25: front end 26: opening 26a: guide surface 30: collar 31: outer circumferential surface A: press-fit direction S: gap V: imaginary circle

Claims (4)

A collar press-fitting structure including a resin fixing portion having a through hole and a cylindrical collar press-fitted into the through hole,
When the front side and the rear side in the press-fitting direction of the collar into the through hole are defined as the front side and the rear side,
an inner peripheral surface of the through hole is provided with a contact portion that fits along an outer peripheral surface of the collar and contacts the outer peripheral surface; and a pressing portion that is provided at a portion of the circumferential direction of the through hole and protrudes inward beyond the contact portion when the collar is not pressed in, but presses the outer peripheral surface of the collar when the collar is pressed in,
an inner circumferential surface of the through hole is provided forward of the pressing portion, the inner circumferential surface of the through hole being provided with a relief recess for forming a gap between the inner circumferential surface of the collar and the relief recess;
The relief recess is provided at a position in the circumferential direction where the pressing portion is provided,
a portion of an inner circumferential surface of the through hole adjacent to the relief recess in the circumferential direction is the abutment portion,
The entire front end surface of the collar is exposed to the outside of the through hole .
Press-fit collar structure. A plurality of the pressing portions are provided at intervals from one another in the circumferential direction,
The relief recesses are provided at positions corresponding to the pressing portions, respectively.
The press-fit structure of the collar according to claim 1 . The relief recess extends to the front end of the through hole.
The press-fit structure for a collar according to claim 1 or 2. Both ends of the relief recess in the circumferential direction are located outside both ends of the pressing portion in the circumferential direction.
The press-fit structure for a collar according to any one of claims 1 to 3.