US3697942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Early warning brake fault device and system
Assignee: Individual
•
Filing: 1971-08-19
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Granted: 1972-10-10
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Expires: 1991-08-19
Abstract
Abstract An early warning system in a motor vehicle having a hydraulic brake system to signal potential brake failure due to a loss of brake fluid from the brake system, or to excessive wear of lining on the brake shoes or disc pads at the wheels. The loss is measured as a volume loss of brake fluid, by a magnetically actuated reed switch structure responsive to a control magnet positioned in the brake fluid reservoir at a position below the reed switch to close the same when the brake fluid has reached a predetermined lower level.
Inventors
- 👤 Loren P Hocking
- 👤 Louis B Lotti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:21
CPC Classifications
F; F16; F16D; F16D66/00; F16D66/02; F16D66/021; F16D66/022; F16D66/025; B; B60; B60T; B60T17/00; B60T17/18; B60T17/22; B60T17/225; G; G01; G01F; G01F23/00; G01F23/14; G01F23/18; G01F23/185
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
156 words
A liquid level indicating device in a hydraulically operated vehicle brake system comprising in combination a master brake cylinder housing having a brake fluid reservoir, a removable cover for said housing overlying and forming a chamber above said reservoir, means removably securing said cover to said housing, means in said cover to admit air at atmospheric pressure to said chamber, a membrane secured by said cover upon said housing and having a portion thereof adapted to move responsively to and with the brake fluid level in said reservoir, said housing cover and said membrane defining said chamber, an electrical magnetically-responsive normally open switching device secured in said chamber to and upon said membrane portion, a control magnet for said switching device and support means therefor disposed in the brake fluid in said reservoir below said membrane, said switching device being connected to and in an electric circuit including a signalling element responsive to said switching device.
Claim 2
Dependent Claim
156 words
A liquid level indicating device in a hydraulically operated vehicle brake system comprising in combination a master brake cylinder housing having a brake fluid reservoir, a removable cover for said housing overlying and forming a chamber above said reservoir, means removably securing said cover to said housing, means in said cover to admit air at atmospheric pressure to said chamber, a membrane secured by said cover upon said housing and having a portion thereof adapted to move responsively to and with the brake fluid level in said reservoir, said housing cover and said membrane defining said chamber, an electrical magnetically-responsive normally open switching device secured in said chamber to and upon said membrane portion, a control magnet for said switching device and support means therefor disposed in the brake fluid in said reservoir below said membrane, said switching device being connected to and in an electric circuit including a signalling element responsive to said switching device.
Claim 3
Dependent Claim
33 words
The device defined in claim 1, wherein said switching device is normally disposed above the field of influence of said control magnet when the brake fluid is at normal level in said reservoir.
Claim 4
Dependent Claim
46 words
The device defined in claim 1, wherein said control magnet support means comprises a member having legs extending downwardly to and upon the bottom wall and at the sides of said reservoir, said control magnet being disposed in magnetic alignment with and below said switching device.
Claim 5
Dependent Claim
57 words
The device defined in claim 1, wherein said control magnet support means comprises a member having its ends secured at the top edge of said reservoir to said membrane and a medial web portion disposed in said brake fluid, said control magnet being secured to said web portion in magnetic alignment with and under said switching device.
Claim 6
Dependent Claim
47 words
The device defined in claim 1, wherein said control magnet is disposed below said switching device a distance such that the magnetic field of influence of said control magnet is inoperative to close said switching device when the brake fluid is at normal level in said reservoir.
Claim 7
Dependent Claim
52 words
The device defined in claim 1, wherein said switching device support means comprises a flexible resilient diaphragm secured by and between said cover and the peripheral edge of said housing about said reservoir, the medial portion of said diaphragm being adapted to rest and ride upon said brake fluid in said reservoir.
Claim 8
Dependent Claim
24 words
The device defined in claim 6, wherein said diaphragm medial portion is provided with a recess, said switching device being seated in said recess.
Claim 9
Dependent Claim
21 words
The device defined in claim 7, wherein such switching device is adhesively secured to said diaphragm medial portion in said recess.
Claim 10
Dependent Claim
16 words
The device defined in claim 1, wherein said switching device comprises a magnetically actuated reed switch.
Claim 11
Dependent Claim
24 words
The Device defined in claim 9, wherein said reed switch is biased to circuit-closing position by the coercive magnetic influence of said control magnet.
Claim 12
Dependent Claim
32 words
The device defined in claim 1, wherein said electric circuit comprises a source of electric power, a vehicle ignition switch, said signalling element, said switching device, and said master brake cylinder housing.
Claim 13
Dependent Claim
15 words
The device defined in claim 11, wherein said signalling element comprises a visible signal lamp.
Claim 14
Dependent Claim
40 words
The device defined in claim 11, wherein said control magnet has an effective magnetic influence upon said switching device directly related to a predetermined level of brake fluid in said reservoir at which said signalling element is to be energized.
Claim 15
Dependent Claim
46 words
The device defined in claim 1, wherein said control magnet is spaced apart from and free of direct connection to said switching means, said switching means being responsive to the magnetic field of influence produced by said control magnet at a lower predetermined brake fluid level.
Claim 16
Dependent Claim
46 words
The device defined in claim 9, wherein said control magnet is spaced apart from and free of direct connection to said reed switch, said reed switch being responsive to the magnetic field of influence produced by said control magnet at a lower predetermined brake fluid level.
Claim 17
Dependent Claim
80 words
The device defined in claim 9, wherein said reed switch comprises an encapsulating housing, and a pair of magnetically responsive switch contacts within said housing each connected to a conductor issuing from said housing, one of said conductors being secured and grounded to said cover within said chamber by a connecting flexible grounding conductor, the second of said conductors issuing from said chamber through said cover for connection to and in said electric circuit by a connecting flexible current conductor.
Claim 18
Dependent Claim
105 words
The device defined in claim 9, wherein said reed switch comprises an encapsulating housing, and a pair of magnetically responsive switch contacts within said housing each connected to a conductor issuing from said housing and terminating in a connected flexible conductor, each of said flexible conductors being insulated and disposed within the body of said membrane, one of said flexible conductors issuing from said membrane body and being grounded to said housing at an edge face of said membrane, the second of said flexible conductors issuing from said membrane body at the side edge of said membrane for connection in and to said electric circuit.
Claim 19
Dependent Claim
35 words
The device defined in claim 1, and including a magnetically responsive member secured and disposed in association with said switching device upon said membrane for improved response to the magnetic influence of said control magnet.
Claim 20
Dependent Claim
26 words
The device defined in claim 18, wherein said magnetically responsive member comprises an iron or steel plate member disposed below said switching device upon said membrane.
Claim 21
Dependent Claim
27 words
The device defined in claim 18, wherein said magnetically responsive member comprises an iron or steel clip at least partially encircling the body of said switching device.
Claim 22
Dependent Claim
85 words
The device defined in claim 16, wherein said flexible grounding conductor terminates in a ground strap disposed in grounding contact with and under a peripheral edge of said cover and upon a peripheral edge of said membrane about said reservoir, and said flexible current conductor is electrically insulated and passes under said cover peripheral edge and said membrane peripheral edge and extends from said connected reed switch conductor to a point beyond said master brake cylinder housing for connection to and in said electric circuit.
References Cited (Backward Citations)
US3450853A
Cited
US3560918A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |