Connection structure and valved connection member

Details Connection structure and valved connection member Connection structure and valved connection member

2001-09-24

2002-06-04

Buiz, Michael Powell (Department: 3753)

Fluid handling

Line condition change responsive valves

Direct response valves

C251S149600

Reexamination Certificate

active

06397884

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valved connection member favorably usable in an evaporation piping system of an automobile fuel tank, etc. and to a connection structure using the valved connection member.
2. Description of the Related Art
The internal pressure of an automobile fuel tank built up by evaporated gasoline is controlled through connection of the fuel tank and a canister located on the engine side by means of piping. Specifically, a check valve is installed in an evaporation line connecting the fuel tank and the canister so as to allow flow of evaporated gasoline from the fuel tank to the engine but not in the reverse direction.
Conventionally, the fuel tank and the check valve are connected by means of a rubber hose, and the check valve and the canister are also connected by means of a rubber hose. Connections are each clamped from outside the rubber hose by means of a clamp member, such as a clip. However, such connection practice involves an increase in the number of components and very complicated connection work, resulting in increased cost.
According to recent tendencies, in order to suppress permeation of gasoline and to improve connection workability, a resin tube is used in place of a rubber hose. Resin tubes are used in the following manner. Resin tubes are connected to corresponding opposite ends of the check valve, and quick connectors are connected to the respective free ends of the resin tubes. The quick connectors are used for connection to the fuel tank and the canister.
A conventionally used check valve is configured such that a valve body is movably disposed within a substantially cylindrical housing, while being biased toward a valve seat formed at one end of the housing by means of a valve spring. Accordingly, the conventional check valve is a separate member from the quick connector and the rubber hose or resin tube and is press-fitted, for use, into an end portion of the rubber hose or the resin tube. Also, assembly of the check valve is complicated in terms of process and accuracy; for example, welding upper and lower housing halves is required.
As mentioned above, since the check valve to be installed in, for example, an evaporation piping system of an automobile fuel tank, is a separate member from the quick connector and the rubber hose or resin tube, the number of components increases and connection work becomes complicated, resulting in difficulty in reducing cost.
In order to meet recent requirements for further reduction in gasoline permeability, even very small permeation from a connection between the rubber hose or the resin tube and the check valve cannot be disregarded. Thus, a reduction in connections between components is an effective means for suppression permeation of gasoline.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-mentioned problems, and to provide a connection member of simple structure equipped with a check valve allowing a reduction in the number of components of a piping system, such as an evaporation piping system, that requires installation of a check valve, and a reduction in the number of connections, as well as to provide a connection structure of low gasoline permeability and low cost favorably usable in, for example, an evaporation piping system employing a valved connection member.
To achieve the above object, according to a first aspect of the present invention, a connection structure comprises a valved connection member and a flexible tube connected to the valved connection member. The valved connection member comprises a cylindrical connection member, a cylindrical valve cap, a cylindrical valve body, and a compression spring. The cylindrical connection member comprises a cylindrical nipple portion formed at one end and allowing the inner circumferential surface of an end portion of the flexible tube to be fitted thereto; and an annular first end face portion formed at an end part of the nipple portion in such a manner as to face toward the one end and to extend radially. The cylindrical valve cap comprises a small-diameter portion and a large-diameter portion, an axial bore formed in the small-diameter portion being smaller in diameter than an axial bore formed in the large-diameter portion; a valve seat portion having a valve seal surface formed on the inner circumferential surface of the cylindrical valve cap and located between the small-diameter portion and the large-diameter portion; and a fitting end portion formed at one end of the large-diameter portion away from the small-diameter portion and fitted to the outer circumferential surface of the end part of the nipple portion of the connection member. The cylindrical valve body comprises a bottom portion having an abutment part to abut the valve seal surface of the valve cap; a cylindrical open end portion extending from the bottom portion and opening toward the connection member; an annular second end face portion formed at the open end portion in such a manner as to face the first end face portion and to extend radially; a first sliding portion extending radially outward from the open end portion in an integral condition; and a first flow path portion provided in the first sliding portion and allowing flow of fluid. The valve body is accommodated within the large-diameter portion of the valve cap in such a manner as to be axially slidable by virtue of the first sliding portion. The compression spring is disposed between the first end face portion and the second end face portion and adapted to bias the valve body toward the valve seal surface. One end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the outer circumferential surface of the end part of the nipple portion of the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap.
According to the first aspect of the present invention, since the valve body is biased toward the valve seat portion by means of the compression spring, the abutment part of the bottom portion of the valve body is in close contact with the valve seal surface of the valve cap. Accordingly, when the upstream fluid pressure of the connection structure is lower than the downstream fluid pressure, a flow path including the first flow path portion is closed to thereby disable flow of fluid. In contrast, when the upstream fluid pressure becomes higher than the downstream fluid pressure, the valve body moves toward the connection member against the compression spring. Thus, the abutment part of the bottom portion of the valve body moves away from the valve seal surface and toward the connection member, thereby forming a gap between the abutment part and the valve seal surface. As a result, the flow path including the first flow path portion is opened to thereby permit downstream flow of fluid. In this case, the valve body can smoothly move within the large-diameter portion in the axial direction by virtue of the first sliding portion. Also, the first flow path portion provided in the first sliding portion smoothens flow of fluid.
Since the connection structure is configured such that the valve body is accommodated within the valve cap fitted to the connection member, the number of components as well as the number of connections can be reduced. Thus, the cost of the connection structure can be reduced, and assembly work time can be shortened.
Even though the valve cap is merely fitted to the outer circumferential surface of the end part of the nipple portion of the connection member, since one end portion of the flexible tube is fitted to the outer circumferential surface of the valve cap fitted to the connection member and is further fitted to the outer circumferential surface of the nipple portion extending away from the outer circumferential surface of the valve cap, the connection can exhibit low gasoline permeability. Since no welding is required for connection of t

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