Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-02-23
2001-05-01
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
Reexamination Certificate
active
06223727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seal member mounting structure in an electromagnetic fuel injection valve, and particularly, to an improvement in a seal member mounting structure including a step which is formed on an outer periphery of a valve housing having a valve seat at its front end and which faces a front end of the valve housing, a seal positioning ring made of a synthetic resin, which is mounted on the outer periphery of the valve housing to abut against the step, a cap which is fitted over and locked to an outer periphery of the front end of the valve housing to define an annular seal mounting groove on an outer peripheral surface of the valve housing by cooperation with the seal positioning ring, and an annular seal member which is mounted in the seal mounting groove to come into close contact with an inner peripheral surface of a mounting bore provided in an intake manifold of an engine.
2. Description of the Related Art
Such seal member mounting structure in the electromagnetic fuel injection valve is already known, as disclosed, for example, in Japanese Patent Application Laid-open No.5-288130.
In the conventionally known seal member mounting structure in the electromagnetic fuel injection valve, the seal positioning ring is formed integrally on the valve housing by molding. Therefore, the width of the annular seal mounting groove defined on the outer peripheral surface of the valve housing by the combination of the seal positioning ring and the cap can be stabilized to provide a good sealing function to the seal member mounted in the annular seal mounting groove.
However, when the structure including the seal positioning ring formed integrally on the valve housing by molding is employed, a troublesome post-treatment for removing a flash protruding toward the seal mounting groove is required, which is disadvantageous in cost. Moreover, there is a possibility that the seal mounting groove may be damaged during the post-treatment.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a seal member mounting structure of the above-described type in an electromagnetic fuel injection valve, wherein a seal positioning ring can be mounted easily and precisely in a regular position on an outer peripheral surface of a valve housing, thus eliminating the post-treatment.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a seal member mounting structure in an electromagnetic fuel injection valve, comprising a step which is formed on an outer periphery of a valve housing having a valve seat at its front end and which faces a front end of the valve housing, a seal positioning ring made of a synthetic resin, which is mounted on the outer periphery of the valve housing to abut against the step, a cap which is fitted over and locked to an outer periphery of the front end of the valve housing to define an annular seal mounting groove on an outer peripheral surface of the valve housing by cooperation with the seal positioning ring, and an annular seal member which is mounted in the seal mounting groove to come into close contact with an inner peripheral surface of a mounting bore provided in an intake manifold of an engine, wherein the valve housing has a fitting surface over which the seal positioning ring is fitted, the fitting surface being formed of a diameter smaller than that of an annular sealing surface which serves as a bottom surface of the seal mounting groove, and a tapered surface which is connected to a rear edge of the sealing surface and which is decreased in diameter toward the fitting surface, and the seal positioning ring is formed so that the ring is fitted over the fitting surface past a state in which it has been forced onto the sealing surface, the seal positioning ring having a resilient projection formed thereon, the resilient projection being placed in pressure contact with the tapered surface in a state in which the seal positioning ring has been fitted over the fitting surface.
With the first feature, when the seal positioning ring is fitted over the fitting surface past the state in which it has been forced onto the sealing surface, the seal positioning ring is retained reliably in a position to abut against the step by a reaction force generated by the resilient projection of the seal positioning ring coming into pressure contact with the tapered surface. Therefore, when the seal member and the cap are then mounted sequentially on the valve housing, the width of the seal mounting groove between the seal positioning ring and the cap can correctly be maintained constant at all times. Thus, when the electromagnetic fuel injection valve is mounted in the mounting bore in the intake manifold, the amount of seal member deformed by the inner peripheral surface of the mounting bore is constant at all times and hence, the seal member can exhibit a stable sealing function. In addition, it is unnecessary to carry out a post-treatment such as the removal of a flash, which can contribute to a reduction in manufacture cost.
According to a second aspect and feature of the present invention, in addition to the first feature, the seal positioning ring is provided with an annular lightening recess which opens into one end surface thereof.
With the second feature, the weight of the seal positioning ring can be reduced by the lightening recess, and the resiliency of an inner peripheral wall of the seal positioning ring can be regulated, thereby enabling the seal positioning ring to pass easily through the state in which the seal positioning ring has been forced onto the sealing surface.
According to a third aspect and feature of the present invention, in addition to the second feature, the resilient projection is formed integrally at a front end of an inner peripheral wall of the seal positioning ring, which is surrounded by the lightening recess.
With the third feature, the shape of the seal positioning ring is simplified by the integral formation of the resilient projection with the inner peripheral wall and hence, it is possible to easily form the seal positioning ring by molding.
According to a fourth aspect and feature of the present invention, in addition to the first feature, the valve housing is comprised of a cylindrical valve housing body in which a movable core is accommodated, and a valve seat member which is fitted to an inner peripheral surface of a front end of the valve housing body and which has the valve seat at a front end of the valve seat member, the fitting surface being formed on an outer periphery of the valve housing body, the sealing surface and the tapered surface being formed on an outer periphery of the valve seat member.
With the fourth aspect and feature, the fitting surface, the sealing surface having a larger diameter than that of the fitting surface, and the tapered surface disposed between the fitting surface and the sealing surface, can be formed easily and accurately without grooving.
According to a fifth aspect and feature of the present invention, in addition to the first feature, the step is formed by a front end of a covering member made of a synthetic resin and coupled to the outer peripheral surface of the valve housing to cover a coil surrounding the valve housing.
With the fifth feature, the step, against which the seal positioning ring is put into abutment, can be formed without formation of a special flange or step on the valve housing by utilizing the covering member covering the coil, thereby simplifying the structure and providing a reduction in manufacture cost.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4294215 (1981-10-01), Hans et al.
patent: 5189782 (1993-03-01), Hickey
patent: 5752487 (1998-05-01), Harrell et al.
patent: 6102007 (2000-08-01), Furst
patent: 5-288130 (1993-11-01), None
Shoji Manabu
Tahara Toshihiro
Arent Fox Kintner & Plotkin & Kahn, PLLC
Keihin Corporation
Moulis Thomas N.
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