Fluid handling – Systems – Multi-way valve unit
Patent
1991-06-24
1992-11-17
Michalsky, Gerald A.
Fluid handling
Systems
Multi-way valve unit
25112902, 25112908, 25112919, F15B 13044
Patent
active
051634775
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an electrohydraulic proportional or directional control valve having a solenoid to which is supplied an electric current so as to control the pressure of a pressurized oil supplied to an output side of the control valve.
DESCRIPTION OF THE PRIOR ART
In a conventional electrohydraulic proportional or directional control valve, as shown in FIG. 1, a sleeve-like element 3 is slidably mounted in a valve bore 2 formed in a valve body 1 of the control valve. In the sleeve-like element 3 are formed an inlet port 4 and a drain port 5. The sleeve-like element 3 has its front-end interior portion 3a communicated with an outlet port 6 formed in the valve body 1 of the control valve. A spool valve 7 is slidably mounted in the sleeve-like element 3. In the spool valve 7 are formed: an axial bore 8; and a radial port 9 which communicates with the axial bore 8 and is formed in a small-diameter portion 7a of the spool valve 7. A compression spring 10 is provided to spring bias the spool valve 7 into a position in which: an area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7 communicates with the drain port 5; and a moving rod 11a of a solenoid 11, which rod 11a is oppositely disposed from the spool valve 7, and abuts on a base-end surface of the spool valve 7. When an electric current is supplied to the solenoid 11 to energize the same, the solenoid 11 has the moving rod 11a thereof move leftward as viewed in FIG. 1 so that the spool valve 7 is pushed leftward by the moving rod 11a of the solenoid 11 to reach a position in which an area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7 communicates with the inlet port 4, whereby the pressurized oil supplied from a hydraulic pump P is supplied to the outlet port 6 through: the inlet port 4; the area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7; radial port 9; axial bore 8; and the front-end interior portion 3a of the sleeve-like element 3. The control valve having the above construction is well known.
In the above conventional control valve, by controlling the stroke of the moving rod 11a of the solenoid 11 through control of an amount of the electric current supplied to the solenoid 11, it is possible to increase/decrease an opening area of the inlet port 4 communicating with the area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7. Consequently, in such a conventional control valve, the pressure of the pressurized oil in the outlet port 6 may be controlled so as to be directly proportional to the amount of the electric current supplied to the solenoid 11.
However, in the conventional control valve described above, in the case where no electric current is supplied to the solenoid 11, the spool valve 5 moves into a position in which: the area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7 communicates with the drain port 5; and the outlet port 6 communicates with a reservoir 12, so that no pressure exists in the outlet port 6. In the case where air exists in an outlet-side passage of a hydraulic circuit of the control valve, such air is compressed when the solenoid 11 is energized to press its moving rod 11a against the spool valve 7 so as to have the pressure of the pressurized oil in the outlet port build up to a predetermined level. Consequently, such compression of air considerably impairs the responsiveness the control valve. In addition, in the conventional control valve having the above construction, the spool valve 7 takes too much time until the area defined between the sleeve-like element 3 and the small-diameter portion 7a of the spool valve 7 reaches a position in which the area communicates with the inlet port 4, and, therefore, in this respect, the responsiveness of the conventional control valve is further impaired.
SUMMARY OF THE INVENTION
Under such c
REFERENCES:
patent: 3556155 (1971-01-01), McWilliams
patent: 4316599 (1982-02-01), Bouvet et al.
patent: 4548383 (1985-10-01), Wolfges
patent: 4579145 (1986-04-01), Leiber et al.
patent: 4635683 (1987-01-01), Nielsen
Ishizaki Naoki
Nunotani Sadao
Takano Toshiro
Kabushiki Kaisha Komatsu Seisakusho
Kananen Ronald P.
Michalsky Gerald A.
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