Electricity: circuit makers and breakers – Fluid pressure – Diaphragm
Reexamination Certificate
2002-12-04
2003-09-16
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Fluid pressure
Diaphragm
C200S0830SA, C200S0830SA
Reexamination Certificate
active
06621021
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a differential pressure switch having a piston, which is guided in a cylinder bore of a piston housing against the force of a return element, the piston head having a pressure P
1
applied to it, while the bore space around a tapered shaft of the piston has a pressure P
2
applied to it, a switching process being triggered by movement of the piston.
2. Description of Related Art
The previously known differential pressure switches have the disadvantage that the switching process is performed using a piston and switching element that is located in the liquid or gaseous medium whose pressure is to be measured or whose pressure is to be used for switching.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a differential pressure switch and/or sensor in which the actual switching or display process occurs uninfluenced by the type, temperature, and/or pressure of the medium being measured or sensed.
It is a further object to provide differential pressure switch and/or sensor which will attain the foregoing object, yet can be constructed simply and cost-effectively, and in this case, will suppress the penetration of moisture in order to avoid the occurrence of error or leakage currents, in the region of the switching element, which may impair the switching processes.
The objects according to the present invention are achieved by a differential pressure switch, which may be implemented in the same way as a differential pressure sensor, in which the piston tip, which cooperates with a switching element, is sealed in relation to the cylinder bore by a rolling diaphragm, which is movable within the range of the axial movement of the piston.
REFERENCES:
patent: 2468768 (1949-05-01), Malick
patent: 4339955 (1982-07-01), Iwasaki
patent: 4460812 (1984-07-01), Asahi
patent: 4503301 (1985-03-01), Kurtz
patent: 4644116 (1987-02-01), Miyakawa
patent: 4654643 (1987-03-01), Meisenheimer
patent: 4703140 (1987-10-01), Poling
patent: 4767898 (1988-08-01), Yasuda et al.
patent: 5216213 (1993-06-01), Sato
patent: 5373127 (1994-12-01), Homol
patent: 5538185 (1996-07-01), Rabitsch et al.
patent: 44 14 739 (1994-11-01), None
patent: 1947 575 (1996-10-01), None
patent: 0 676 785 (1995-10-01), None
Marto Arno
Pechhold Frank
Beru AG
Friedhofer Michael
Nixon & Peabody LLP
Safran David S.
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