JP3248653B2 - Dust cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-proof cap, and more particularly to a dust-proof cap which is difficult to fall off from a mating pipe.

[0002]

2. Description of the Related Art Conventionally, when a precision machined product such as a fuel pump is shipped, a dustproof cap or the like is attached to a pipe portion or the like of the precision machined product so that foreign matter such as dust and dirt can be precisely removed from the pipe portion. We do not invade the inside of processed product. For example, a conventional dust cap 27 shown in FIG.
Is fitted to the suction pipe 5 of the fuel pump 1 as shown in FIG. 8, for example. The fuel pump 1 includes a motor unit 3 and a pump unit 4, and supplies fuel sucked from a suction pipe 5 to a first impeller 11 and a second impeller 12.
Thus, the liquid is discharged from the discharge pipe 6 via the pump chamber 13. The motor unit 3 has an armature 14 fixed to a motor shaft 8, and a magnet 15 for rotating the armature 14 by an electromagnetic force is fixed inside the housing by a holding plate spring 17. Electrical connector 7
A first impeller 11 and a second impeller 12 are fixed in the rotation direction to a tip end of a motor shaft 8 driven by a current supplied from the motor, and the first impeller 11 is
The second impeller 12 is housed between the pump casing 21 and the pump spacer 2.
Housed between the two. A metal bearing 16 that rotatably supports the motor shaft 8 is mounted on a pump casing 21, and a thrust receiving pin 24 of the motor shaft 8 is mounted on a pump cover 23.

When the fuel pump 1 is shipped, the suction-side dustproof cap 27 is attached to the outer peripheral surface of the suction pipe 5 before the shipment.
And a discharge-side dustproof cap 28 is press-fitted into the outer peripheral surface of the discharge pipe 6.

[0004]

According to such a conventional fuel pump, after checking the performance of the pump with a test oil such as a solvent or gasoline, the suction-side dustproof cap 27 and the discharge-side dustproof cap are attached to the pump. 28
After arriving at the shipping destination, the suction-side dustproof cap 27 and the discharge-side dustproof cap 28 are removed, and the pump is assembled in the fuel tank of the vehicle.

[0005] However, if the residual oil of the inspection oil used during the process inspection before shipping adheres to the suction pipe of the fuel pump, etc., when the dustproof cap is press-fitted into the suction side pipe, the dustproof cap remains. There is a possibility that the cap swells with the oil, that is, absorbs the oil and the cap expands, and as a result, the dustproof cap falls off the suction side pipe. In order to prevent such a dust-proof cap from falling off, there is a method of press-fitting the dust-proof cap into the suction-side pipe, and then tightening the outer peripheral side of the dust-proof cap with a collar member or the like. If so, the cost will increase due to the increase in the number of parts.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dust-proof cap which can be fitted to a pipe portion and is difficult to fall off.

[0007]

According to a first aspect of the present invention, there is provided a dustproof cap capable of being fitted to a mating mounting pipe, wherein the outer periphery of the mating mounting pipe is provided. An outer tubular portion having an open end that can be fitted to a wall, a lid having a flange-shaped portion connected to the opposite open end of the outer tubular portion, and projecting from the inner wall of the lid toward the outer tubular portion. And an inner cylindrical portion having a bottomed end surface formed inside the outer cylindrical portion.

According to a second aspect of the present invention, the inner cylindrical portion has an outer diameter dimension such that a part of its outer peripheral wall is in close contact with the inner wall surface of the mating mounting pipe when it swells. According to a third aspect of the present invention, the distal end surface of the inner tubular portion is located on the inner side of the open end of the outer tubular portion. A fourth aspect of the present invention is characterized in that the dustproof cap is integrally formed of low-density polyethylene.

According to a fifth aspect of the present invention, there is provided a dustproof cap made of injection-molded resin. In claim 6, the fuel pump can be fitted to a pump unit, a motor unit for driving the pump unit, a discharge pipe and a suction pipe, and at least one of the discharge pipe and the suction pipe. The dustproof cap according to any one of claims 1 to 5, is provided.

[0010]

According to the dustproof cap of the first aspect, the inner wall of the outer cylindrical portion of the dustproof cap is fitted to the outer peripheral wall of the mating mounting pipe. The dust cap is prevented from falling off. After fitting, the dust-proof cap itself may swell if the dust-proof cap itself absorbs residual oil or the like adhering to the mating mounting pipe, but at the time of this swelling, the outer cylindrical portion expands, and the rattling from the mating mounting pipe occurs. May occur, on the contrary, since the outer diameter of the inner cylindrical portion is enlarged,
A part of the outer peripheral wall of the inner cylindrical portion comes into close contact with the inner wall surface of the mating mounting pipe. For this reason, also at the time of swelling, falling off of the dust-proof cap from the mating attachment pipe is prevented.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. A first embodiment of the dustproof cap of the present invention applied to a fuel pump for an internal combustion engine as a precision machined product will be described.
FIG. 1 shows that the dustproof cap 37 according to the present invention is
FIG. 2 shows a state fitted to the suction pipe 5 of FIG.
A sectional view of the dust cap 37 is shown.

First, the structure of the fuel pump shown in FIG. 1 will be described. The fuel pump 1 comprises a motor section 3 and a pump section 4, and the fuel sucked from a suction pipe 5 is supplied to a first impeller 11 and a second impeller 11. The discharge is performed from the discharge pipe 6 via the pump chamber 13 by the impeller 12. The motor unit 3 has an armature 14 fixed to a motor shaft 8, and a magnet 15 for rotating the armature 14 by an electromagnetic force is fixed inside the housing by a holding plate spring 17. A first impeller 11 and a second impeller 12 are fixed to a distal end of a motor shaft 8 driven by a current supplied from the electric connector 7,
The first impeller 11 is housed between the pump cover 23 and the pump spacer 22, and the second impeller 12 is housed between the pump casing 21 and the pump spacer 22. Further, a metal bearing 16 that rotatably supports the motor shaft 8 is attached to a pump casing 21,
The thrust receiving pin 24 of the motor shaft 8 is attached to the pump cover 23.

The dustproof cap 37 is integrally formed by injection molding of a resin such as polyethylene. The dust-proof cap 37 is composed of an outer cylindrical portion 38, a lid portion 39, and an inner cylindrical portion 40 when each part is divided. Each part will be described in turn.
The outer cylindrical portion 38 is cylindrical and has an open end 38 a at one end, and the other end 38 b is connected to the lid 39. The outer cylindrical portion 38 is a surface with which the inner peripheral wall 38c on the opening end 38a side comes into contact with the outer peripheral wall of the suction pipe 5 of the fuel pump 1 at the time of press-fitting.

The lid portion 39 is annularly connected to the other end 38b of the outer cylindrical portion 38 to cover the closing portion thereof, and has a flange portion 39a having a diameter larger than the outer diameter of the outer cylindrical portion 38. . The thickness of the lid portion 39 is such that the thickness of the flange portion 39a protruding radially outward is greater than the thickness of the outer cylindrical portion 38, and the thickness of the lid portion 39b of the radially inner portion of the outer cylindrical portion 18 is the thickness of the outer cylindrical portion 38. It is thinner than the thickness.

The inner cylindrical portion 40 is formed in a convex shape. Specifically, the inner cylindrical portion 40 is formed into a bottomed cylindrical shape inside the outer cylindrical portion 38 from the inner surface side of the lid portion 39. The thickness of the inner cylindrical portion 40 is formed to be substantially the same as the thickness of the outer cylindrical portion 38. The outer diameter of the inner cylindrical portion 40 is set to such an extent that it is not pressed into the inner wall of the suction pipe 5. This is because the inner cylindrical portion 40 does not play a role of press-fitting at a portion guided by the suction pipe 5 at the time of fitting. Further, the convex tip surface 40 of the inner cylindrical portion 40 is formed.
a is stopped inside so as not to protrude outside from the opening end 38a of the outer cylindrical portion 38. This is because when the dustproof cap 37 is left alone, the tip surface 40a exists inside the opening end 38a of the outer cylindrical portion 38 so that dust, dust, and the like do not directly adhere to the tip surface 40a. It is. When such foreign matter such as dust adheres to the tip end surface 40a of the inner cylindrical portion 40, when the dustproof cap 37 is pressed into the suction pipe 5 or the like, the foreign matter or the like is removed.
This is because there is a great risk of intrusion into the inside of the device.

As a material of the dustproof cap 37, for example, low-density polyethylene is used, but a thermoplastic resin such as polypropylene can also be used. In this embodiment,
Outer diameter of the suction pipe 5 of the fuel pump 1: 11.15 mm,
Inner diameter: 7.45 mm, whereas dust cap 37
The inner diameter of the outer cylindrical portion 38 is 10.65 mm,
Has an outer diameter of 7.45 mm. The reason why the inner diameter of the outer cylindrical portion 38 is smaller than the outer diameter of the suction pipe 5 is that the inner peripheral wall 38c of the outer cylindrical portion 38 is fitted tightly to the outer peripheral wall of the suction pipe 5 at the time of press-fitting. The outer diameter of the inner cylindrical portion 40 is substantially equal to the inner diameter of the suction pipe 5 because the inner cylindrical portion 40 fits smoothly inside the suction pipe 5 and the pipe This is to prevent burrs and the like from being generated during press-fitting with the inner peripheral wall.

In the present invention, it is desirable that the outer diameter of the inner cylindrical portion 40 be equal to or slightly smaller than the inner diameter of the pipe. This prevents burrs from being generated at the time of press-fitting, and immediately after press-fitting, the outer cylindrical portion 38 is tightly joined to the outer periphery of the pipe so as to prevent falling off. Even if the outer cylindrical portion 38 swells and expands, the inner cylindrical portion 40 similarly swells so that the inner cylindrical portion 40 comes into close contact with the inner wall of the pipe so as to press the dustproof cap 37 from the suction pipe 5. This is to ensure that dropout is prevented.

According to the present embodiment, at the time of press-fitting into the suction pipe 5, immediately after the press-fitting, the inner peripheral wall of the outer cylindrical portion 38 is in close contact with the outer peripheral wall of the suction pipe 5, and when swollen, the outer peripheral wall of the inner cylindrical portion 40 is sucked. In order to adhere to the inner peripheral wall of the pipe 5, the suction pipe 5
It is possible to reliably prevent the dust-proof cap 37 from falling off. According to this embodiment, after the dustproof cap 37 is fitted to the suction pipe 5, the dustproof cap 37 is prevented from falling off without using a collar member or the like. And the like can be prevented from entering.

Next, FIGS. 3, 4 and 5 show the results of experiments conducted on the change in the load of the dustproof cap from the suction pipe. (1) Change in pull-out load In the experiment, five test pieces (n = 5) of the dust-proof cap were pressed into the suction pipe, and then the initial pull-out load when the dust-proof cap was removed was measured. Then, after the dust-proof cap was fitted to the suction pipe, only the suction pipe and the dust-proof cap were immersed in the inspection residue oil (solvent) for 72 hours, and the load of the dust-proof cap coming off the suction pipe was measured. The test product is the same as the conventional product shown in FIG.
This was performed for each of the dust caps of the first embodiment of the present invention shown in FIG. The experimental results are shown in FIG. FIG.
Are the average values of the initial load and the load after the immersion for 72 hours. Specific numerical values are as shown in FIGS. FIG. 4 shows the first embodiment of the present invention.
FIG. 5 is a bar graph showing the initial detachment load of the example product and the detachment load after immersion for 72 hours for each of the five test articles. FIG. 5 shows the initial detachment load of the conventional product and the detachment load after immersion for 72 hours. Each of the five articles is represented by a bar graph.

As can be seen from the experimental results, as shown in FIG. 4, in the product of the first embodiment, even after immersion in the test residue oil for 72 hours, the removal load remains to some extent.
As a result, it can be understood that the dust cap is hard to fall off from the suction pipe. On the other hand, as shown in FIG. 5, in the conventional product, although the initial detachment load was high, the detachment load of the dust-proof cap was almost zero after immersion in the inspection residue oil for 72 hours. It can be understood that it easily falls off.

In the embodiment of the present invention, as described above, since the inner peripheral wall of the suction pipe and the outer peripheral wall of the inner cylindrical portion are more closely contacted by the self-swelling action of the inner cylindrical portion of the dustproof cap, the inner cylindrical portion of the dustproof cap is dropped due to the close contact of the dustproof cap. It is considered that the prevention function works. (2) Dimensional change Next, one reference experiment was conducted to find out the cause of the above-mentioned dropout prevention function. In this experiment, a single dust-proof cap was used, and the test product was the same as that of the first embodiment. This test product was immersed in inspection residue oil (solvent), and the immersion time and the outside of the dust-proof cap were measured. The relationship between the inner diameter of the cylinder 38 and the outer diameter of the inner cylinder 40 was measured. FIG. 6 shows the result.

As shown in the graph of FIG. 6, since the inner diameter of the outer cylindrical portion 38 gradually increases as the immersion time increases from the initial size, it can be seen that there is a risk of rattling. On the other hand, as for the outer diameter of the inner cylindrical portion 40, similarly, it is presumed that the effect that the outer peripheral wall of the inner cylindrical portion 40 fits and adheres to the inner peripheral wall of the suction pipe works by gradually increasing the size from the initial size. Is done. Therefore, it is considered that the effect that the dust-proof cap hardly comes off from the suction pipe and hardly comes off due to the fitting and fitting action. Such a fitting / adhering effect is not a conventional product.
Since the conventional product does not have an inner cylindrical portion, such a fall prevention function does not work. Therefore, it is considered that the conventional product easily falls off.

Next, a dustproof cap according to a second embodiment of the present invention is shown in FIG. The dustproof cap 47 according to the second embodiment shown in FIG.
Consists of zero. Since the outer cylindrical portion 38 and the lid portion 39 have the same shape as that of the first embodiment shown in FIG. 2, the description is omitted. The inner cylindrical portion 50 has a protruding tip portion formed in a thin truncated cone shape. The thin-walled frustoconical portion 50a is located inside the open end 38a at one end of the outer cylindrical portion 38 and does not protrude outside. Since the inner cylindrical portion 50 has a truncated conical shape, it can be fitted so as to be guided by the inner portion of the suction pipe.
Since the inner cylindrical portion 50 is located inside the opening end 38a of the outer cylindrical portion 38, foreign matter such as dust and dirt does not easily adhere to the truncated cone portion 50a of the inner cylindrical portion 50. This is because, when the dustproof cap is fitted to the precision fitting product, it is considered to minimize the invasion of foreign matter and the like into the precision fitting product.

According to this embodiment, before shipping, the fuel pump 1
The dust pump 47 is press-fitted into the suction pipe 5, and the fuel pump with the dust cap is transported and assembled after arriving at the destination. At this time, the dust cap is removed from the suction pipe. From before shipment to before assembly, the dust-proof cap is securely attached to the fuel pump without dropping off, so foreign matter can be reliably prevented from entering the fuel pump, which is a precision machined product with the dust-proof cap. There is an effect that.

In the above embodiment, the inner cylindrical portion of the dust-proof cap is formed to be thin, but in the present invention, the inner cylindrical portion of the dust-proof cap may be formed to be a solid cylinder.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a fuel pump to which a dust cap of the present invention is applied.

FIG. 2 is a sectional view of a dustproof cap according to a first embodiment of the present invention.

FIG. 3 is a data diagram showing experimental data of a change in a detachment load of the dustproof cap according to the first embodiment of the present invention.

FIG. 4 is an experimental data diagram showing a change in a detachment load according to the first embodiment of the present invention.

FIG. 5 is an experimental data diagram showing a change in a detachment load of a conventional product.

FIG. 6 is an experimental data diagram showing a dimensional change of the product of the first embodiment of the present invention.

FIG. 7 is a sectional view of a dustproof cap according to a second embodiment of the present invention.

FIG. 8 is a partially cutaway side view showing a state in which a conventional dust cap is attached to a fuel pump.

FIG. 9 is a sectional view of a conventional dustproof cap.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel pump 2 Housing 3 Motor part 4 Pump part 5 Suction pipe 37 Dustproof cap 38 Outer cylinder part 39 Lid part 40 Inner cylinder part 50 Inner cylinder part 50a Thin-walled truncated cone part

Claims (6)

(57) [Claims] 1. A dustproof cap that can be fitted to a mating-side mounting pipe, an outer cylindrical portion having an open end that can be fitted to an outer peripheral wall of the mating-side mounting pipe, and a non-opening end of the outer cylindrical portion. A lid having a flange-shaped portion connected to the inner cylinder, and an inner cylinder formed so as to protrude from the inner wall of the lid toward the outer cylinder, and having a bottomed end surface formed inside the outer cylinder. And a dust-proof cap. 2. The dustproof cap according to claim 1, wherein the inner cylindrical portion has an outer diameter such that a part of its outer peripheral wall is in close contact with the inner wall surface of the mating attachment pipe when swelled. 3. The dustproof cap according to claim 1, wherein a front end surface of the inner cylindrical portion is located on an inner side with respect to the opening end of the outer cylindrical portion. 4. The dustproof cap according to claim 1, wherein the dustproof cap is integrally formed of low-density polyethylene. 5. The dustproof cap according to claim 1, which is an injection molded resin dustproof cap. 6. A pump section, a motor section for driving the pump section, a discharge pipe and a suction pipe, and at least one of the discharge pipe and the suction pipe can be fitted to the pump section. A fuel pump comprising: the dustproof cap according to any one of claims 1 to 7.