Fluid handling – Convertible – Units interchangeable between alternate locations
Reexamination Certificate
1997-10-07
2001-04-24
Shaver, Kevin (Department: 3754)
Fluid handling
Convertible
Units interchangeable between alternate locations
C251S129020, C251S129070, C251S129180
Reexamination Certificate
active
06220277
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a variable flow solenoid for the pilot control of an hydraulic valve.
2. Description of Related Art
In hydraulic control systems, it may be required to vary the flow of oil controlling the speed of a mechanical element, for example the speed of a hydraulic elevator. This can be done by employing known solenoid type proportional valves which respond to the signals given by a computer, this having received measurements of the actual speed of the elevator, comparing this speed with the value of a pre-determined target speed and calculating the required adjustment of electrical power to the proportional valve solenoid effecting oil flow to achieve the required correction of elevator speed.
Proportional valves are more complex in their design than standard open-closed type solenoid valves and far more expensive. Both of these types are shown in the drawings (see description of FIG.
1
and
FIG. 2
in Brief Description of the Drawings).
SUMMARY OF THE INVENTION
It is an object of the invention to employ the major parts of low cost standard open closed type solenoid valves with inexpensive modifications such that the rate of oil flow through the solenoid valve is relative to the electrical power supply to the solenoid coil, as with a proportional valve.
A further object of the invention is to reduce manufacturing and stocking costs of two essential types of flow metering valves by providing the options of having the flow path of the solenoid either “open” or “closed” in their position of rest when no electrical power is applied, employing identical parts in the solenoid assembly, with one minor exception.
A further object of the invention is to achieve interchangeability between a standard open-close two position type solenoid and a variable flow solenoid without the requirement of additional installation space or any other modification to the main hydraulic valve manifold.
REFERENCES:
patent: 2893428 (1959-07-01), Collins
patent: 4205592 (1980-06-01), Haussler
patent: 5163477 (1992-11-01), Takano et al.
patent: 5218999 (1993-06-01), Tanimoto
patent: 5535783 (1996-07-01), Asou et al.
patent: 5593004 (1997-01-01), Blain
patent: 5853028 (1998-12-01), Ness et al.
patent: 5879060 (1999-03-01), Megerle et al.
patent: 465736 (1950-06-01), None
patent: 1054298 (1959-04-01), None
patent: 29 42 886 (1981-05-01), None
patent: 0 762 025 (1997-03-01), None
Letter dated Jan. 1, 1998 from Roy W. Blain to Eugene Chovanes, and attachment (total 7 pages).
Bui Thach H.
Chovanes Eugene
Shaver Kevin
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