Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2000-04-07
2001-12-04
Michalsky, Gaerald A. (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C137S625660
Reexamination Certificate
active
06325102
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a servo driving pilot-type solenoid valve for driving a valve member by increasing an operation force by a pilot fluid pressure output from a pilot valve.
PRIOR ART
According to a pilot-type solenoid valve disclosed in Japanese Patent Application Laid-open No.H11-2357, for driving a spool valve, the spool valve is provided at its one end with a first piston to which a pilot pressure is always applied, and is provided at the other end with second and third pistons. Pilot pressure is individually applied to the second and third pistons so that both the pistons drive a spool. If the supply of the pilot pressure is stopped, the spool valve is returned by the pilot pressure which is always applied to the first piston. A responsibility of a reciprocating motion of the spool is stabilized by these pistons, and an outer appearance of the valve is thinned.
According to the pilot-type solenoid valve of such a structure, a supply/discharge path of the pilot pressure applied to each of the pistons from the pilot valve is complicated, there is no compatibility with components of general pilot-type solenoid valves and therefore, it is difficult to provide a product inexpensively.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished to solve the above problem, and a technical object of the invention is to provide a servo driving pilot-type solenoid valve for driving a valve member by increasing an operation force by a pilot fluid pressure output from a pilot valve so that valve member can reliably be switched.
Another technical object of the invention is to provide a servo driving pilot-type solenoid valve in which a valve member can be driven by piston even with a low pressure, thereby increasing a driving pressure range.
Still another technical object of the invention is to provide a servo driving pilot-type solenoid valve in which compatibility with components of general pilot-type solenoid valve is increased, and the servo driving pilot-type solenoid valve is reduced in size like the general pilot-type solenoid valve.
To achieve the above objects, a servo driving pilot-type type solenoid valve of the present invention comprises: a main valve portion including a plurality of ports, a valve hole which is in communication with the ports, and a flow path switching valve member slidably inserted into the valve hole; a pilot driving mechanism including a pushing member disposed in one end of the valve member, and a pilot valve for supplying a pilot fluid to the pushing member, the pilot driving mechanism switching the valve member by the pushing member which is operated by effect of a pilot fluid pressure; and a returning mechanism for applying a returning force caused by a fluid pressure or a spring to the other end of the valve member, wherein the pushing member in the pilot driving mechanism comprises a first piston operated by the pilot fluid pressure from the pilot valve, and a second piston having substantially the same diameter as that of the first piston and operated by the pilot fluid pressure and a pushing force by the first piston, the first piston includes a shaft which air-tightly passes through a partition wall which divides both the pistons from each other and whose tip end abuts against the second piston, and a guide hole passing through the first piston and its shaft for guiding the pilot fluid pressure to a driving side pressure chamber of the second piston, and the second piston is disposed such that the second piston abuts against one end of the valve member and is operated by the operation force of the pilot fluid pressure introduced from the guide hole into a pressure chamber and by a pushing force of the first piston, thereby pushing the valve member.
In the above servo driving pilot-type solenoid valve, first and second interposition blocks can be disposed such as to be connected to each other between the pilot valve and a valve body of the main valve portion, a cylinder portion on which the first piston slides can be provided in the first interposition block located closer to the pilot valve, and the second interposition block located closer to the valve body can be provided with the partition wall through which the shaft of the first piston passes, and with a cylinder portion on which the second piston slides.
Further, an interposition block can be provided between the pilot valve and a valve body of the main valve portion, the interposition block can be provided therein with a cylinder portion on which the first piston slides and a partition wall through which the shaft of the first piston passes, and an end of the valve body of the main valve portion closer to the pilot valve can be formed with a cylinder portion on which the second piston slides.
The servo driving pilot-type solenoid valve of the above-described structure includes, as the pilot driving mechanism for pushing the valve member by the pushing member to switch the valve member, the first piston for applying the pilot fluid pressure from the pilot valve, and the second piston which is pushed by the first piston and which is also pushed by the pilot fluid pressure to push the valve member. Therefore, a force by the pilot fluid pressure output from the pilot valve is increased by these piston and the valve member can be driven, the valve member can reliably be switched and at the same time, the valve member can be driven by piston even with a low pressure, thereby increasing a driving pressure range.
In the above servo driving pilot-type solenoid valve, the first and second interposition blocks are superposed on each other between the pilot valve and the valve body, the cylinder portions on which the first and second pistons slide are provided in these interposition blocks, the pilot fluid pressure is introduced into the driving side pressure chamber of the first piston from the pilot valve, and the pilot fluid pressure is introduced into the driving side pressure chamber of the second piston through the first piston and the guide hole in its shaft. With this structure, it is possible to use components common to general pilot-type solenoid valve except the first and second interposition blocks superposed on each other between the pilot valve and the valve body as well as the first and second pistons and the like. The flow paths of the pilot valve are also common and therefore, the compatibility of the components is increased and the products can be produced inexpensively. Further, the servo driving pilot-type solenoid valve can be reduced in size like general pilot-type solenoid valve.
Further, in the above servo driving pilot-type solenoid valve, a single interposition block is provided between the pilot valve and a valve body of the main valve portion, the interposition block is provided therein with a cylinder portion on which the first piston slides, and the end of the valve body closer to the pilot valve is formed with a cylinder portion on which the second piston slides. With this structure also, compatibility with components of general pilot-type solenoid valve can be increased, and the servo driving pilot-type solenoid valve can be reduced in size like the general pilot-type solenoid valve.
REFERENCES:
patent: 11-2357 (1999-01-01), None
Ishikawa Makoto
Misumi Keiji
Michalsky Gaerald A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
SMC Corporation
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