Patent US3666903A successfully refreshed from Google Patents.
US3666903A
Expired / Lapsed
US
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Fluid level detector
Assignee: Bendix Corp
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Filing: 1970-11-23
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Granted: 1972-05-30
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Expires: 1990-11-23
Abstract
Abstract A fluid level detector for use in a master cylinder to determine if the brake fluid has dropped below a predetermined level. The fluid level detector is a three piece construction with a probe being made from a conductive, anti-corrosive substance, such as carbon, that is not subject to electrolysis formations. A retaining member formed from a non-conductive, rubber-like substance is inserted through a hole in the side of the master cylinder to secure the probe in a fixed position and, simultaneously, seals the hole in the side of the master cylinder. A conductive metal piece which extends into the retainer provides a connection to the probe from the outside of the master cylinder. As the fluid in the master cylinder drops below and out-of-contact with the probe, the resistance between the probe and the master cylinder housing will approach infinity. As the resistance approaches infinity a signal will be transmitted to an indicator to alert the operator of a low fluid level in the master cylinder.
Inventors
- 👤 George Thomas Bata
- 👤 Winford Boyd Carruth
- 👤 Thomas Francis Gosnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:18
CPC Classifications
H; H01; H01H; H01H35/00; H01H35/18; G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/241; G01F23/242
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
183 words
A fluid level detector comprising: probe means formed from a conductive, non-corrosive, antielectrolysis forming substance for insertion into a fluid containing a conductive container, said probe means being a carbon bar; means for retaining said probe means in said container, said retaining means being a non-conductive, rubber-like substance for easy insertion in a hole in said container and thereafter preventing said fluid from leaking through said hole; and means for connecting said probe means to an external circuit through said retaining means, said connecting means providing an external point for measuring resistance between said probe means and said conductive container, said resistance approaching infinity as the level of said fluid drops below said probe means, said connecting means having a conductive metal piece that extends from substantially one end of said retaining means through the other end thereof, said metal piece being press fitted over one end of said carbon bar with said press fit being enclosed within saId retaining means, said metal piece extending through said retaining means to provide said external point for connecting to said external circuit outside said container.
Claim 2
Dependent Claim
183 words
A fluid level detector comprising: probe means formed from a conductive, non-corrosive, antielectrolysis forming substance for insertion into a fluid containing a conductive container, said probe means being a carbon bar; means for retaining said probe means in said container, said retaining means being a non-conductive, rubber-like substance for easy insertion in a hole in said container and thereafter preventing said fluid from leaking through said hole; and means for connecting said probe means to an external circuit through said retaining means, said connecting means providing an external point for measuring resistance between said probe means and said conductive container, said resistance approaching infinity as the level of said fluid drops below said probe means, said connecting means having a conductive metal piece that extends from substantially one end of said retaining means through the other end thereof, said metal piece being press fitted over one end of said carbon bar with said press fit being enclosed within saId retaining means, said metal piece extending through said retaining means to provide said external point for connecting to said external circuit outside said container.
Claim 3
Dependent Claim
77 words
The fluid level detector, as recited in claim 1, wherein said retaining means is a generally cylindrical, non-conducting rubber member having a conical section followed by an indentation into which the wall of said container will securely fit, said conical section allowing easy insertion into said hole of said container, and having an abutting plate larger than said hole formed on the end thereof to help prevent leakage and secure said fluid level detector in said hole.
Claim 4
Dependent Claim
210 words
A brake fluid level detector for use in a master cylinder of a vehicular braking system, said detector comprising: probe means having a cylindrical carbon body, said carbon being electrically conductive without being substantially effective by electrolytic formations; connector means having one end secured to said carbon body and the other end joined to an external electrical circuit; and retaining means for encapsulating the end of said carbon body secured to said connector means, said retaining means having an external conical, cylindrical and plate sections, said retaining means being an electrically non-conductive resilient member, said retaining means being inserted through a hole in the side of said master cylinder to bring said carbon body into contact with a reservoir of electrically conductive brake fluid, said conical, cylindrical and plate sections of the retaining means resiliently engaging the housing of the master cylinder surrounding said hole to seal said hole and prevent leakage of said brake fluid from said reservoir; said external electrical circuit being adapted to measure electrical resistance between the carbon body and the master cylinder, said brake fluid transmitting said electrical resistance from the master cylinder to said carbon body, said electrical resistance approaching infinity if the fluid level in the master cylinder drops below said cylindrical bar.
Claim 5
Dependent Claim
210 words
A brake fluid level detector for use in a master cylinder of a vehicular braking system, said detector comprising: probe means having a cylindrical carbon body, said carbon being electrically conductive without being substantially effective by electrolytic formations; connector means having one end secured to said carbon body and the other end joined to an external electrical circuit; and retaining means for encapsulating the end of said carbon body secured to said connector means, said retaining means having an external conical, cylindrical and plate sections, said retaining means being an electrically non-conductive resilient member, said retaining means being inserted through a hole in the side of said master cylinder to bring said carbon body into contact with a reservoir of electrically conductive brake fluid, said conical, cylindrical and plate sections of the retaining means resiliently engaging the housing of the master cylinder surrounding said hole to seal said hole and prevent leakage of said brake fluid from said reservoir; said external electrical circuit being adapted to measure electrical resistance between the carbon body and the master cylinder, said brake fluid transmitting said electrical resistance from the master cylinder to said carbon body, said electrical resistance approaching infinity if the fluid level in the master cylinder drops below said cylindrical bar.
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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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |