Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2001-12-31
2003-07-29
Hirsch, Paul J. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129140
Reexamination Certificate
active
06598852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solenoid valve, and particularly to an improvement in a solenoid valve including a coil assembly accommodated in a solenoid housing made of a magnetic metal and having an end wall at one end thereof, a movable core which is opposed to a stationary core magnetically connected to the end wall and inserted into one end of a center bore and which is inserted into the other end of the center bore, a yoke plate made of a magnetic metal which is opposed to the other end of the coil assembly and coupled to the other end of the solenoid housing, a collar made of a non-magnetic material which is adapted to guide the axial movement of the movable core and inserted into the other end of the center bore through the central portion of the yoke plate, a valve member accommodated in a valve housing connected to the solenoid housing, and a rod operatively connected to the movable core and connected to the valve member.
2. Description of the Related Art
Such a solenoid valve is conventionally well-known, for example, from Japanese Patent Application Laid-open No.3-157576 and the like. In this solenoid valve, one end of the rod is coaxially fitted in the movable core.
However, the conventionally known solenoid valve is of an arrangement such that the movable core and the rod are substantially integral with each other, and moreover the axial movement of only the movable core is guided. For this reason, the position of an axial center of the rod is influenced by the concentricity between the movable core and the rod and the accuracy of the position of the axial center of the collar adapted to guide the movable core. To ensure the smooth axial movements of the movable core and the rod within the collar and the valve housing, the processing accuracy and assembling accuracy of the collar adapted to guide the movable core, the movable core and the rod must be increased, thereby bringing about an increase in cost.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a solenoid valve, wherein the processing and assembling of the collar, the movable core and the rod can be facilitated to provide a reduction in cost.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a solenoid valve comprising a coil assembly including a bobbin made of a synthetic resin and having a center bore, and a coil wound around the bobbin, the coil assembly being accommodated in a solenoid housing made of a magnetic metal and having an end wall at one end thereof; a stationary core magnetically coupled to the end wall and inserted into one end of the center bore; a movable core opposed to the stationary core and inserted into the other end of the center bore; a yoke plate made of a magnetic metal, which has a through-bore in its central portion and which is opposed to the other end of the coil assembly and coupled to the other end of the solenoid housing; a collar made of a non-magnetic material adapted to guide the axial movement of the movable core and inserted into the other end of the center bore through the through-bore; and a valve member which is accommodated in a valve housing connected to the yoke plate and to which a rod operatively connected to the movable core is connected, wherein the valve housing is provided with a guide portion for guiding the axial movement of the rod, and one end of the rod is put into coaxial abutment against the other end of the movable core.
With such arrangement of the first feature, the movable core and the rod are separate from each other and hence, it is unnecessary to increase the processing accuracy for assembling the movable core and the rod to each other, and even if the axial centers of the movable core and the rod are offset slightly from each other, an adverse influence cannot be exerted to the axial movement of the movable core and the rod separately guided by the collar and the guide. Therefore, it is possible to facilitate the processing and assembling of the collar, the movable core and the rod, thereby providing a reduction in cost.
According to a second aspect and feature of the present invention, in addition to the arrangement of the first feature, the valve housing made of a synthetic resin is integrally connected to the bobbin through a plurality of connecting bores provided in the yoke plate. With such arrangement, the bobbin, the yoke plate and the valve housing are integrally connected to one another and hence, the accuracy of the axial centers of the bobbin, the yoke plate and the valve housing can be enhanced easily.
According to a third aspect and feature of the present invention, in addition to the arrangement of the second feature, an outer periphery of the yoke plate integrally coupled by molding between the valve housing and the bobbin is coupled to the solenoid housing on the side opposite from the end wall. With such arrangement, the assembling can be facilitated by integrally coupling the yoke plate upon the formation of the bobbin and the valve housing connected to each other through the connecting bores in the yoke plate.
According to a fourth aspect and feature of the present invention, in addition to the arrangement of the first feature, the collar which has at one end thereof an outward-facing collar portion protruding radially outwards and opposed to an inner surface of the center bore is press-fitted into the through-bore. With such arrangement, the collar is press-fitted into the through-bore using the outward-facing collar portion exerting no influence to the sliding movement of the movable core within the collar. Thus, it is possible to press-fit the collar having a thickness at a small valve to the utmost into the through-bore, whereby the distance between the movable core and the yoke plate can be set at a small value to the utmost to enhance the magnetic characteristic, and the axial movement of the movable core can be guided by the collar fixed to the yoke plate.
According to a fifth aspect and feature of the present invention, in addition to the arrangement of the fourth feature, the collar is provided at the other end thereof with an inward-facing collar portion protruding radially outwards, and one end of the rod through which the inward-facing collar portion is axially movably passed is put into coaxial abutment against the other end of the movable core within the collar. With such arrangement, the other end of the collar is substantially occluded by the rod and hence, it is possible to prevent the entrance of dust into the collar to the utmost.
According to a sixth aspect and feature of the present invention, in addition to the arrangement of the first feature, the yoke plate has a cylindrical portion integrally provided at a center thereof to protrude on the side opposite from the coil assembly and to define a portion of the through-bore. With such arrangement, the collar is supported over an axially relatively long distance by the cylindrical portion integral with the yoke plate and in this manner, the axis of the collar can be prevented to the utmost from being inclined. In addition, it is possible to increase the area of a portion of the yoke plate opposed to an outer surface of the movable core through the collar, and to provide an enhancement in magnetic characteristic by an increase in area of a magnetic path.
According to a seventh aspect and feature of the present invention, in addition to the arrangement of the first or sixth feature, the movable core is integrally provided with a smaller-diameter portion inserted into the collar, and a larger-diameter portion formed to have a diameter larger than that of the smaller-diameter portion and coaxially connected to one end of the smaller-diameter portion at a location outside axially one end of the collar in such a manner that it is opposed to the other end of the stationary core. With such arrangement, despite the insertion of the collar into the center bore in the bobbin, the area of opposition of t
Hino Noboru
Nagasaki Akira
Ryuen Shigeto
Shibata Masayuki
Tomoda Shinichiro
Arent Fox Kintner & Plotkin & Kahn, PLLC
Hirsch Paul J.
Keihin Corporation
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