Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
1999-10-22
2001-01-30
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C251S129080
Reexamination Certificate
active
06179005
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. § 119 with respect to Japanese Application No. 10(1998)-302600 filed on Oct. 23, 1998, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention generally relates to a flow control or pressure control valve. More particularly, the present invention pertains to a spool valve type electromagnetic valve used for controlling flow or pressure.
BACKGROUND OF THE INVENTION
A conventional electromagnetic valve used for flow controlling or pressure controlling includes a valve body having an inlet port, an outlet port and a drain port. A spool is fitted in the valve body in a slidable manner and is adapted to be operated in such a manner that the spool is in a counter balanced state by being applied with an output force of a linear solenoid and the urging force of a spring, the hydraulic pressure at the output port, or the sum of the hydraulic pressure at the output port and the urging force of the spring. An electromagnetic valve of this type is disclosed in Japanese Patent Laid-Open Publication No. Hei.7-301346 published without examination in 1995.
With this type of electromagnetic valve, to obtain the designed performance of the valve, smooth movements of the spool and a plunger from which the output force of the linear solenoid is derived are necessary and are established subject to coaxial alignment between the spool and the plunger. To realize this coaxial alignment in the known electromagnetic valve, an alignment engaging portion is provided between a casing of the linear solenoid and the valve body.
However, with this construction, a higher dimensional precision is required for the casing and the related parts or elements by which the plunger is aligned with the casing. This need for precision makes it difficult to reduce the production costs associated with known electromagnetic valve constructions.
In addition, to avoid direct engagement of the plunger with a yoke when electric current flowing through the coil of the linear solenoid reaches its maximum value, a stopper member formed from non-magnetic material is provided between the plunger and yoke. This also contributes to making it difficult to reduce the production cost associated with the known electromagnetic valve constructions.
In light of the foregoing, a need exists for a spool valve type electromagnetic valve which is not as susceptible to the aforementioned disadvantages and drawbacks.
It would thus be desirable to provide a spool valve type electromagnetic valve having a coaxially aligned spool and plunger that is capable of being manufactured at a lower cost.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a spool valve type electromagnetic valve includes a linear solenoid, a valve body provided with a bore and having a connecting end that is connected to the linear solenoid, and a spool fitted in the bore for sliding movement. The valve body includes an inlet port, an outlet port and a drain port, with the inlet port, the outlet port, and the drain port being in fluid communication with the bore. The spool is urged in one direction by a spring which applies an urging force to the spool and is in a counter balanced condition by the output force of the linear solenoid and the urging force of the spring. The spool is moved to effect an inverse proportional control of the opening area of a passage extending from the inlet port to the outlet port relative to an opening area of a passage extending from the outlet port to the drain port. The linear solenoid includes a resin-made bobbin, a rear yoke around which a coil is wound, a plunger movably fitted in the rear yoke, and a front yoke positioned in the resin-made bobbin in coaxial alignment with both the rear yoke and the connecting end of the valve body. The front yoke, the rear yoke and the resin-made bobbin form an insert molded integrated structure, and an alignment facilitating portion is provided between the front yoke and the valve body.
According to another aspect of the invention, a spool valve type electromagnetic valve includes a linear solenoid, a valve body provided with a bore and having a connecting end that is connected to the linear solenoid, and a spool slidably positioned within the bore and urged in one direction by an urging member. The valve body possesses an inlet port, an outlet port and a drain port, with the inlet port, the outlet port, and the drain port being in fluid communication with the bore. The spool is movable to control the opening area of a passage extending from the inlet port to the outlet port and the opening area of a passage extending from the outlet port to the drain port. The linear solenoid includes a rear yoke, a resin-made bobbin around which a coil is wound, a plunger movably fitted in the resin-made bobbin, and a front yoke positioned in the resin-made bobbin in coaxial alignment with both the rear yoke and the connecting end of the valve body. The resin-made bobbin possesses engaging portions that engage engaging portions of the front yoke and the rear yoke to form an integrated structure between the front yoke, the rear yoke and the resin-made bobbin.
In accordance with another aspect of the invention, a spool valve type electromagnetic valve includes a linear solenoid, a valve body provided with a bore and having a connecting end that is connected to the linear solenoid, and a spool slidably positioned within the bore and urged in one direction by an urging member. The valve body includes an inlet port, an outlet port and a drain port that are in fluid communication with the bore. The spool is movable to control the opening area of a passage extending from the inlet port to the outlet port and the opening area of a passage extending from the outlet port to the drain port. The linear solenoid includes a rear yoke, a bobbin around which a coil is wound, a plunger movably fitted in the bobbin, a front yoke positioned in the bobbin in coaxial alignment with both the rear yoke and the connecting end of the valve body, and a stopper member integrally formed in one piece and at the same time with the bobbin for regulating sliding movement of the plunger toward the front yoke. The stopper member extends radially inwardly to be contacted by the plunger.
REFERENCES:
patent: 4971116 (1990-11-01), Suzuki et al.
patent: 7-301346 (1995-11-01), None
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Michalsky Gerald A.
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