US5602373A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pressure switch with an adjusting piston driven by a restoring spring for an oil-separating air filter
Assignee: Mann and Hummel GmbH
•
Filing: 1995-04-06
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Granted: 1997-02-11
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Expires: 2015-04-06
Abstract
Abstract A differential pressure switch particularly suitable for monitoring dirt accumulation on a filter element of an oil-separating air filter comprising a piston which is movable in response to a relative change in pressure between two pressure zones and is biased in one direction by a restoring spring, and a rolling membrane which separates the pressure zones.
Inventors
- 👤 Bernd Sauer
- 👤 Michael Wolf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:12
CPC Classifications
H; H01; H01H; H01H35/00; H01H35/24; H01H35/247; G; G01; G01L; G01L13/00; G01L13/02; G01L13/025; G01L19/00; G01L19/08; G01L19/10; H01H35/34
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
136 words
A differential pressure indicator for use in a system including an oil separating air filter element which separates an unfiltered air zone from a filtered air zone and which filters a mixture of air and oil, comprising a housing, a piston arranged in said housing and exposed to pressures of two different pressure zones, one of said pressure zones being in communication with said unfiltered air zone, and the other of said pressure zones being in communication with said filtered air zone, and a rolling member arranged in said housing adjacent one end of said piston, wherein said piston is movable in response to a relative change in pressure between said two pressure zones and is biased in one direction by a restoring spring, and wherein said different pressure zones are separated by said rolling membrane.
Claim 2
Dependent Claim
136 words
A differential pressure indicator for use in a system including an oil separating air filter element which separates an unfiltered air zone from a filtered air zone and which filters a mixture of air and oil, comprising a housing, a piston arranged in said housing and exposed to pressures of two different pressure zones, one of said pressure zones being in communication with said unfiltered air zone, and the other of said pressure zones being in communication with said filtered air zone, and a rolling member arranged in said housing adjacent one end of said piston, wherein said piston is movable in response to a relative change in pressure between said two pressure zones and is biased in one direction by a restoring spring, and wherein said different pressure zones are separated by said rolling membrane.
Claim 3
Dependent Claim
14 words
A differential pressure indicator according to claim 1, wherein the indicator comprises a switch.
Claim 4
Dependent Claim
16 words
A differential pressure indicator according to claim 1, wherein the rolling membrane is reinforced by fabric.
Claim 5
Dependent Claim
18 words
A differential pressure indicator according to claim 1, wherein the rolling membrane is mounted in a force-locking manner.
Claim 6
Dependent Claim
27 words
A differential pressure indicator according to claim 4, wherein an O-ring is interposed between the rolling membrane and the housing in order to increase the force locking.
Claim 7
Dependent Claim
54 words
A differential pressure indicator according to claim 1, wherein the piston has substantially conical configuration at one end and is housed in a cylinder having said rolling membrane mounted adjacent one end thereof, said one cylinder end having a corresponding substantially conical configuration into which the substantially conical end of the piston is received.
Claim 8
Dependent Claim
35 words
A differential pressure indicator according to claim 2, wherein said piston carries a magnetic element which actuates the switch when the piston is moved in response to a predetermined pressure differential between the pressure zones.
Claim 9
Dependent Claim
40 words
A differential pressure indicator according to claim 7, wherein the switch comprises an annular magnet through which the magnetic element of the piston is moved when the piston moves in response to a predetermined pressure difference between the pressure zones.
Claim 10
Dependent Claim
25 words
A differential pressure indicator according to claim 1, wherein the indicator comprises a transparent cover member through which movement of the piston can be viewed.
Claim 11
Dependent Claim
34 words
A differential pressure indicator according to claim 2, wherein the switch comprises a reed contact which is switched by movement of the piston in response to a predetermined pressure difference between the pressure zones.
Claim 12
Dependent Claim
30 words
A differential pressure indicator according to claim 1, comprising a sensor module which houses the piston and an indicator module secured to said sensor module by a snap detent connection.
Claim 13
Dependent Claim
30 words
A differential pressure indicator according to claim 1, comprising a sensor module which houses the piston and a switch module secured to said sensor module by a snap detent connection.
Claim 14
Dependent Claim
31 words
A differential pressure indicator according to claim 1, comprising a sensor module which houses the piston and an indicator switch module secured to said sensor module by a snap detent connection.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-02-11 | 2000-08-12 | 2001-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-02-11 | 2004-08-12 | 2005-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-02-11 | 2008-08-12 | 2009-02-11 | $7700.00 | Window Closed / Lapsed |