JP4287034B2 - Plug cap ventilation structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ventilation structure of a plug cap for guiding an electric wire to a spark plug in a plug hole.
[0002]
[Prior art]
As this type of plug cap ventilation structure, for example, one disclosed in Japanese Patent Laid-Open No. 9-7682 is known. As shown in FIGS. 7 to 9, the ventilation structure of the plug cap allows air to flow into the plug hole E <b> 1 by a ventilation line provided in the plug cap 1. That is, the plug cap 1 includes an insulating pipe 2 that guides the high-voltage electric wire E2 to a spark plug (not shown) located at the deepest portion in the plug hole E1 provided in the engine head E, and an upper side (one end side) of the plug hole E1. ) And a rubber rain cover 3 that covers the upper opening 2a of the insulating pipe 2 projecting from the opening E1a and leads the high-voltage electric wire E2 from the opening 2a in a liquid-tight manner. Yes. Although not shown, a rubber cap that is in close contact with the peripheral surface of the insulator in the spark plug is provided on the lower side (the other end side) of the insulating pipe 2.
[0003]
In the insulating pipe 2, a concave space is formed by an outer wall 2c and an inner wall 2d extending coaxially from the upper reference end surface 2b. The concave space is divided into two by ribs 2e, one being a water storage tank 2f and the other being a circulation tank 2g. The circulation tank 2g is formed with a ventilation hole 2h connected to the inside of the plug hole E1 from the bottom surface thereof, that is, the reference end surface 2b. The insulating pipe 2 has a flange 2i formed along the reference end face 2b and close to the plug hole E1, and a groove 2j for holding the O-ring 4 is formed on the outer periphery of the flange 2i. Is formed. The insulating pipe 2 is injection-molded with a hard insulating resin material.
[0004]
On the other hand, the rain cover 3 includes a large-diameter portion 3a that fits to the outer wall 2c and a small-diameter portion 3b that fits to the inner wall 2d. The small-diameter portion 3b has an air opening hole 3c connected to the water storage tank 2f. Is formed. Further, the annular flat surface 3d at the boundary between the large diameter portion 3a and the small diameter portion 3b is provided at a position having a predetermined interval with respect to the upper end surface (one end surface) of the outer wall 2c. The large-diameter portion 3a is provided with a skirt portion 3e formed so as to surround an upper end surface (one end surface) and an outer peripheral surface of an annular convex portion E3 described later. The annular protrusion E3 is provided along the opening E1a of the plug hole E1 in the engine head E, and prevents, for example, water applied to the engine head E from flowing into the plug hole E1 as it is. .
[0005]
In the vent structure of the plug cap configured as described above, the circulation tank 2g and the ventilation hole 2h are provided between the atmosphere opening hole 3c, the water storage tank 2f, the upper end surface (one end face) of each rib 2e and the annular flat surface 3d. It becomes a ventilation line, and the pressure in the plug hole E1 can be released to the atmosphere side. Therefore, even if the pressure in the plug hole E1 changes due to, for example, a temperature change, the pressure in the plug hole E1 can be kept constant. In addition, since the air opening hole 3c and the ventilation hole 2h are alternately located, and the water storage tank 2f is provided on the air opening hole 3c side, for example, even if water is applied to the engine during car washing, the water is plugged. It does not enter the hall E1.
[0006]
[Problems to be solved by the invention]
By the way, in the conventional plug cap ventilation structure, it is necessary to make the water storage tank 2f as wide as possible in order to increase the water storage effect. However, the thickness of the outer wall 2c surrounding the water storage tank 2f needs to be ensured to be equal to or greater than a predetermined thickness because of the material strength, and there is a demand from the engine side to reduce the diameter of the plug hole E1. . For this reason, there exists a problem that it is difficult to take the water storage tank 2f widely.
[0007]
In addition, by forming the water storage tank 2f and the flow tank 2g, the injection mold becomes complicated, and the outer wall 2c and the inner wall 2d have a shape extending thinly in a cylindrical shape. Therefore, the outer wall 2c and the inner wall 2d are formed. There is a problem that there is a high possibility that molding failure occurs due to poor filling of the resin (so-called short shot) on the upper end surface (one end surface).
[0008]
The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a plug cap ventilation structure capable of enlarging a water storage tank, simplifying a mold, and reducing a defective rate. .
[0009]
[Means for Solving the Problems]
In order to solve the above problems, an insulating pipe that guides an electric wire to a spark plug in a plug hole, a rain cover that covers an opening of the plug hole and an opening of one end of the insulating pipe located on the opening side The insulating pipe is provided with a small-diameter outer peripheral surface that is reduced in diameter from the main outer peripheral surface on one end side through the step portion, and from the step portion along the small-diameter outer peripheral surface. A rib projecting to one end side, the rain cover is provided with a fitting cylinder portion extending at a predetermined interval from the outer peripheral surface of the small diameter and liquid-tightly fitting to the main outer peripheral surface ; An upper end of the insulating pipe is fitted inside the fitting cylinder part, an air opening hole is provided between the fitting cylinder part and the small-diameter outer peripheral surface, and the rib has an opening at one end thereof. , Provide a ventilation hole in the plug hole, Between the fitting tube portion of the rain cover and the outer peripheral surface of the small diameter of the insulating pipe, the upper end of the insulating pipe is fitted , and the step portion of the insulating pipe is used as the bottom surface, and the rib is partitioned in the circumferential direction. A water tank is formed.
[0010]
In the invention according to claim 1 configured as described above, a step portion of the insulating pipe is used as a bottom surface between the fitting tube portion of the rain cover and the small-diameter outer peripheral surface of the insulating pipe, and the rib is a partition in the circumferential direction. A water storage tank can be configured. Further, the plug hole and the atmosphere side are in communication with each other through the atmosphere opening hole of the rain cover, the water storage tank, and the ventilation hole of the rib.
[0011]
Moreover, since it will be in the state where the conventional outer wall was lost, the part corresponding to the outer wall will become a water storage tank as it is. Accordingly, the water storage tank can be made sufficiently wide. In addition, since the thickness of the outer peripheral surface of the small diameter can be increased and the capacity of the water storage tank can be sacrificed to some extent, it is possible to prevent a molding defect due to defective filling from occurring at one end surface of the outer peripheral surface of the small diameter. Therefore, the defect rate can be reduced. Furthermore, since the outer wall is not required, the structure of the molding die is simplified, and the cost can be reduced.
[0012]
The invention described in claim 2 is characterized in that, in the invention described in claim 1, the rib supports the fitting cylinder portion of the rain cover from the inside.
[0013]
In the invention according to claim 2, since the fitting cylinder part of the rain cover can be supported from the inside by the rib, even when the rain cover is formed of, for example, a material having flexibility, the shape of the fitting cylinder part is changed. It can hold stably and can prevent that a water storage tank narrows.
[0014]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the insulating pipe has a sub-rib that protrudes from the step portion to the one end side along the outer peripheral surface of the small diameter and supports the fitting cylinder portion of the rain cover from the inside. It is characterized by providing.
[0015]
In the invention according to claim 3, the sub-rib can hold the fitting cylinder portion of the rain cover more stably, and the capacity of the water storage tank is further stabilized. Moreover, since the water storage tank is divided into a plurality of parts by the sub-ribs, the water that has infiltrated first accumulates in the water storage tank farthest from the ventilation hole. Therefore, the probability that water enters the plug hole through the ventilation hole can be further reduced.
[0016]
According to a fourth aspect of the present invention, in the first, second, or third aspect of the present invention, the fitting cylinder portion of the rain cover is provided with a seal portion that is in close contact with the plug hole.
[0017]
In the invention according to the fourth aspect, since the seal portion closely contacting the inner surface of the plug hole is provided in the fitting tube portion of the rain cover, the conventionally used sealing means such as an O-ring is not required. Therefore, cost can be reduced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples with reference to FIGS. However, the same reference numerals are given to elements common to the constituent elements of the conventional example, and the description is simplified.
[0019]
The vent structure of the plug cap shown in this embodiment enables the circulation of air into the plug hole E1 by a ventilation line provided in the plug cap 10, as shown in FIGS. A feature is that the water storage tank 5 is formed between the insulating pipe 2 and the rain cover 3.
[0020]
That is, a main outer peripheral surface 21 a is formed on the upper side (one end side) of the insulating pipe 2, and a small-diameter outer peripheral surface 23 a that is reduced in diameter from the main outer peripheral surface 21 a via the step portion 22 is formed. A rib 24 protruding upward from the step portion 22 along the small-diameter outer peripheral surface 23a is formed integrally with the step portion 22 and the small-diameter outer peripheral surface 23a. The small-diameter cylindrical portion 23 constituting the small-diameter outer peripheral surface 23a is formed with an outlet 23b for pulling out the high-voltage electric wire E2 from the side of the upper end portion.
[0021]
The rib 24 is provided at a position corresponding to the outlet 23b, and the height from the step portion 22 is lower than the lower edge of the outlet 23b by a predetermined amount. The rib 24 has an outer peripheral surface 24a that is flush with the main outer peripheral surface 21a, and supports a fitting cylinder portion 31 of the rain cover 3 described later from the inside. Further, a ventilation hole 24b is formed in the rib 24 so as to penetrate vertically along the small-diameter outer peripheral surface 23a. The ventilation hole 24b opens to the upper end surface (one end surface) of the rib 24 and communicates with the plug hole E1 through the main cylindrical portion 21 and the flange portion 2i constituting the main outer peripheral surface 21a. ing.
[0022]
On the other hand, the rain cover 3 is formed with a fitting cylinder portion 31 that is liquid-tightly fitted to the main outer peripheral surface 21a. The fitting cylindrical portion 31 extends in parallel with the small-diameter outer peripheral surface 23a to a position where the expanded inner peripheral surface 31a exceeds the upper end surface of the rib 24 from the step portion 22 and does not reach the lower edge of the outlet 23b. ing. The upper side of the fitting cylinder portion 31 is a reduced diameter cylindrical portion 32 having a reduced diameter inner peripheral surface 32a that is liquid-tightly fitted to the small diameter outer peripheral surface 23a. The boundary between the expanded inner peripheral surface 31 a and the reduced inner peripheral surface 32 a is an annular flat surface 32 b parallel to the step portion 22. Further, the upper side of the reduced diameter cylindrical portion 32 is integrally closed by the top portion 33. Furthermore, a guide cylinder portion 34 that integrally holds the high-voltage electric wire E2 in a liquid-tight manner is formed integrally at a position corresponding to the outlet 23b in the reduced diameter cylindrical portion 32. Further, the reduced diameter cylindrical portion 32 has an air opening hole that connects the inside of the fitting tube portion 31 and the atmosphere side at a position farthest from the rib 24 in the circumferential direction, that is, a position farthest from the ventilation hole 24b. 32c is formed.
[0023]
And between the expanded inner peripheral surface 31a and the small outer peripheral surface 23a, the water storage tank 5 is configured with the stepped portion 22 as the bottom surface, the annular flat surface 32b as the top surface, and the ribs 24 as the circumferential partition. It has become so. The insulating pipe 2 and the rain cover 3 are made of the same material as that shown in the conventional example.
[0024]
In the vent structure of the plug cap configured as described above, the air opening hole 32c of the rain cover 3, the water reservoir 5, the space between the upper end surface of the rib 24 and the annular plane 32b, and the ventilation hole 24b of the rib 24 are provided in the ventilation line. Thus, the inside of the plug hole E1 communicates with the atmosphere side through this ventilation line. And since the conventional outer wall 2c (refer FIG. 7) will be in the state lose | eliminated, the part corresponding to the outer wall 2c will lead to the capacity | capacitance increase of the water storage tank 5 as it is. Therefore, the water tank 5 can be made sufficiently wide. Moreover, since the thickness of the small diameter cylindrical portion 23 can be increased and the capacity of the water storage tank 5 can be somewhat sacrificed, it is possible to prevent the formation failure due to poor filling on the upper end surface of the small diameter cylindrical portion 23. . Therefore, the defect rate can be reduced. Furthermore, since the outer wall 2c is not required, the structure of the molding die is simplified, and the cost can be reduced.
[0025]
Moreover, since the fitting cylinder part 31 of the rain cover 3 can be supported from the inner side by the outer peripheral surface 24a of the rib 24, the shape of the fitting cylinder part 31 formed of a flexible material made of rubber is stably maintained. You can do it. Therefore, the water tank 5 can be maintained in a wide state.
[0026]
In addition, in the said Example, although it comprised so that the fitting cylinder part 31 might be supported from the inner side by one rib 24, as shown in FIG.4 and FIG.5, it is an upper side along the small diameter outer peripheral surface 23a from the step part 22. FIG. You may comprise so that the fitting cylinder part 31 may be hold | maintained by the subrib 25 which protrudes. That is, each of the sub-ribs 25 has an outer peripheral surface 25 a that is flush with the main outer peripheral surface 21 a, and the height from the step portion 22 is the same as the rib 24. 4 is provided at a position opposite to the rib 24 with respect to the center of the insulating pipe 2, and the sub-rib 25 shown in FIG. 5 is provided at a position equally divided into four in the circumferential direction. .
[0027]
When such a sub-rib 25 is provided, the air opening hole 32c of the rain cover 3, each water tank 5, between the upper end surface of the sub-rib 25 and the annular plane 32b, and between the upper end surface of the rib 24 and the annular plane 32b. The ventilation hole 24b becomes a ventilation line. And the fitting cylinder part 31 can be hold | maintained more stably by the outer peripheral surface 25a of the subrib 25. FIG. In addition, when the water tank 5 is divided into a plurality of sub-ribs 25, the water first accumulates in the water tank 5 farthest from the ventilation hole 24b, and the water tank 5 adjacent to the rib 24 Since it functions as a draining tank, the probability that water enters the plug hole E1 through the ventilation hole 24b can be made extremely low. The sub-rib 25 may be provided with a ventilation hole 24b.
[0028]
As shown in FIG. 6, the main outer peripheral surface 21a and the fitting cylinder part 31 are extended to the position of the groove 2j (see FIG. 1) for the O-ring 4, and the fitting cylinder part 31 has a plug hole E1. It may be configured to provide a seal portion 31b that is in close contact with the surface. The seal portion 31b protrudes from the outer peripheral surface of the fitting tube portion 31 in a circular arc shape and presses against the inner peripheral surface of the plug hole E1, and presses the enlarged inner peripheral surface 31a against the main outer peripheral surface 21a by the reaction force. It is like that. Therefore, the cost can be reduced by deleting the O-ring 4 and the liquid tightness between the fitting cylinder portion 31 and the main outer peripheral surface 21a can be enhanced.
[0029]
【The invention's effect】
In the first aspect of the present invention, a water storage tank is formed between the fitting tube portion of the rain cover and the small-diameter outer peripheral surface of the insulating pipe, with the step portion of the insulating pipe as the bottom surface and the rib as a partition in the circumferential direction. be able to. Further, the plug hole and the atmosphere side are in communication with each other through the atmosphere opening hole of the rain cover, the water storage tank, and the ventilation hole of the rib.
[0030]
Moreover, since it will be in the state where the conventional outer wall was lost, the part corresponding to the outer wall will become a water storage tank as it is. Accordingly, the water storage tank can be made sufficiently wide. In addition, since the thickness of the outer peripheral surface of the small diameter can be increased and the capacity of the water storage tank can be sacrificed to some extent, it is possible to prevent a molding defect due to defective filling from occurring at one end surface of the outer peripheral surface of the small diameter. Therefore, the defect rate can be reduced. Furthermore, since the outer wall is not required, the structure of the molding die is simplified, and the cost can be reduced.
[0031]
In the invention according to claim 2, since the fitting cylinder part of the rain cover can be supported from the inside by the rib, even when the rain cover is formed of, for example, a material having flexibility, the shape of the fitting cylinder part is changed. It can hold stably and can prevent that a water storage tank narrows.
[0032]
In the invention according to claim 3, the sub-rib can hold the fitting cylinder portion of the rain cover more stably, and the capacity of the water storage tank is further stabilized. Moreover, since the water storage tank is divided into a plurality of parts by the sub-ribs, the water that has infiltrated first accumulates in the water storage tank farthest from the ventilation hole. Therefore, the probability that water enters the plug hole through the ventilation hole can be further reduced.
[0033]
In the invention according to the fourth aspect, since the seal portion closely contacting the inner surface of the plug hole is provided in the fitting tube portion of the rain cover, the conventionally used sealing means such as an O-ring is not required. Therefore, cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a vent structure of a plug cap shown as an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a main part showing an insulating pipe in the ventilation structure of the plug cap.
FIG. 3 is a plan view showing an insulating pipe in the ventilation structure of the plug cap.
FIG. 4 is a plan view showing an example in which one sub-rib is provided on an insulating pipe in the ventilation structure of the plug cap.
FIG. 5 is a plan view showing an example in which three sub-ribs are provided on an insulating pipe in the ventilation structure of the plug cap.
FIG. 6 is a cross-sectional view of an essential part showing an example in which a seal portion is provided on a rain cover in the ventilation structure of the plug cap.
FIG. 7 is a cross-sectional view of an essential part of a plug cap ventilation structure shown as a conventional example.
FIG. 8 is a cross-sectional view of a principal part showing an insulating pipe in the ventilation structure of the plug cap.
FIG. 9 is a plan view showing an insulating pipe in the ventilation structure of the plug cap.
[Explanation of symbols]
2 Insulating pipe 2a Opening 3 Rain cover 21a Main outer peripheral surface 22 Step portion 23a Small-diameter outer peripheral surface 24 Rib 24b Ventilation hole 25 Sub-rib 31 Fitting cylinder part 31b Sealing part 32c Air opening hole E1 Plug hole E1a Opening part E2 )

Claims (4)

Ventilation structure of a plug cap comprising an insulating pipe for guiding an electric wire to an ignition plug in the plug hole, and a rain cover that covers the opening of the plug hole and an opening on one end side of the insulating pipe located on the opening side Because
The insulating pipe is provided with a small-diameter outer peripheral surface that is reduced in diameter from a main outer peripheral surface on one end side through a step portion, and is provided with a rib that protrudes from the step portion along the small-diameter outer peripheral surface to one end side, Is provided with a fitting cylinder portion extending at a predetermined distance from the outer peripheral surface of the small diameter and liquid- tightly fitting to the main outer peripheral surface, and an upper end of the insulating pipe is provided inside the fitting cylinder portion. Is fitted, and an air opening hole is provided between the fitting tube portion and the small-diameter outer peripheral surface, and the rib is provided with a ventilation hole that opens to one end side thereof and is connected to the plug hole. Between the fitting cylinder portion of the rain cover and the outer peripheral surface of the small diameter of the insulating pipe, the upper end of the insulating pipe is fitted , and the step portion of the insulating pipe is used as the bottom surface, and the rib is a circumferential partition. Plug cap ventilation structure characterized by forming a water storage tank . The ventilation structure of the plug cap according to claim 1,
The plug cap ventilating structure is characterized in that the rib is adapted to support the fitting tube portion of the rain cover from the inside.   The ventilation structure of the plug cap according to claim 1 or 2, wherein the insulating pipe is provided with a sub-rib that protrudes from the step portion to the one end side along the outer peripheral surface of the small diameter and supports the fitting cylinder portion of the rain cover from the inside. Ventilation structure of the plug cap as a feature. In the vent structure of the plug cap according to claim 1, 2, or 3,
A plug cap ventilating structure characterized in that a seal portion that is in close contact with the plug hole is provided in the fitting tube portion of the rain cover.

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