Patent US3602883A successfully refreshed from Google Patents.
US3602883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telltale device for differential pressure
Assignee: TDK Micronas GmbH
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Filing: 1969-03-19
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Granted: 1971-08-31
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Expires: 1989-03-19
Abstract
Abstract A pressure-differential-indicating system which includes a cylinder connected between two compartments across which a pressure differential may develop, e.g. the chambers of a tandem master cylinder. A piston in the cylinder bore is displaceable from its intermediate position under the pressure differential to actuate a switch. The switch actuation occurs via an index ball spring-biased into a V-section recess of the piston in its intermediate position but adapted to rest in a further recess on either side of this intermediate recess when the piston is located in its off-normal position, the limiting recesses maintaining the switch in its actuated state even after the pressure differential has been redressed.
Inventors
- 👤 Juan Belart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:30
CPC Classifications
B; B60; B60T; B60T17/00; B60T17/18; B60T17/22; B60T17/226
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
248 words
A differential-pressure indicating system responsive to a pressure differential between two chambers beyond a threshold differential, said system comprising means forming a differential-pressure bore communicating at opposite sides with said chambers, a differential-pressure piston slidably received in said bore, detent means cooperating with said piston for retaining same in an intermediate position at differential pressures across said chambers below said threshold and in limiting positions to either side of said intermediate position upon the application of a pressure differential to said piston in a corresponding direction above said threshold, and indicating means including switch means cooperating with said detent means and operable upon movement of said piston from said intermediate position to one of said limiting positions and while said piston remains in said one of said limiting positions for signaling the development of said differential above said threshold, said piston being formed with a relative deep intermediate recess and a pair of relatively shallow side recesses axially offset of opposite sides of said intermediate recess, said detent means including a spring-loaded stop ball operatively connected with said switch means and biased in the direction of said piston for engagement in said recesses, said ball entering said intermediate recess to return said switch means in one operating condition while resisting displacement of said piston until said threshold differential is attained and thereafter entering one of said side recesses to a lesser extent to maintain said piston in an extreme position and said switch means in another operative position.
Claim 2
Dependent Claim
248 words
A differential-pressure indicating system responsive to a pressure differential between two chambers beyond a threshold differential, said system comprising means forming a differential-pressure bore communicating at opposite sides with said chambers, a differential-pressure piston slidably received in said bore, detent means cooperating with said piston for retaining same in an intermediate position at differential pressures across said chambers below said threshold and in limiting positions to either side of said intermediate position upon the application of a pressure differential to said piston in a corresponding direction above said threshold, and indicating means including switch means cooperating with said detent means and operable upon movement of said piston from said intermediate position to one of said limiting positions and while said piston remains in said one of said limiting positions for signaling the development of said differential above said threshold, said piston being formed with a relative deep intermediate recess and a pair of relatively shallow side recesses axially offset of opposite sides of said intermediate recess, said detent means including a spring-loaded stop ball operatively connected with said switch means and biased in the direction of said piston for engagement in said recesses, said ball entering said intermediate recess to return said switch means in one operating condition while resisting displacement of said piston until said threshold differential is attained and thereafter entering one of said side recesses to a lesser extent to maintain said piston in an extreme position and said switch means in another operative position.
Claim 3
Dependent Claim
44 words
The system defined in claim 1 wherein said intermediate recess is a circumferential groove having a pair of inwardly converging frustoconical flanks and said side recesses are circumferential grooves having flanks engageable with said ball to retain said piston in the corresponding limiting position.
Claim 4
Dependent Claim
86 words
The system defined in claim 2, further comprisIng a second bore formed therein at right angles to the first-mentioned bore and receiving said ball, said detent means further comprising a plate in said second bore resting against said ball, a compression spring received in said second bore under prestress and bearing on said plate, and a tappet engaging said plate and extending through said second bore, said switch means including a switch means including a switch mounted in said second bore and actuable by said tappet.
Claim 5
Dependent Claim
32 words
The system defined in claim 2, further comprising a pair of stops formed in said bore on opposite sides of said piston and engageable therewith in the limiting positions of said piston.
Claim 6
Dependent Claim
35 words
The system defined in claim 2 wherein said chambers are the hydraulic working chambers of a tandem master cylinder having a body, said bore being formed in said body parallel to the tandem master cylinder.
Claim 7
Dependent Claim
28 words
The system defined in claim 5, further comprising a pair of cross bores formed in said body and connecting the first-mentioned bore at its ends to said chambers.
Claim 8
Dependent Claim
32 words
The system defined in claim 6, further comprising means for venting one of said chambers selectively whereby pressure generated in the unvented chamber serves to return said piston into its intermediate position.
Claim 9
Dependent Claim
54 words
The system defined in claim 7 wherein said indicating means includes an electrically operated warning device on the instrument panel of an automotive vehicle having a dual-network brake system provided with said tandem master cylinder, said vehicle having an ignition battery, said switch means being connected in circuit between said battery and said device.
Claim 10
Dependent Claim
212 words
The system defined in claim 8 wherein said tandem master cylinder is provided with a primary piston shiftable by the vehicle operator and received in one of said chambers, a secondary piston displaceable by said primary piston and received in the other of said chambers, respective springs in said chambers bearing upon said primary and secondary pistons to resist displacement thereby by said operator, stroke limiting means between said primary piston and said secondary piston for directly coupling them upon failure of fluid pressure in the chamber of said primary piston, and stop means on said body engageable by said secondary piston for limiting the displacement thereof upon the failure of fluid pressure in the chamber of said secondary piston, said bore being provided with a pair of stops on opposite sides of said differential-pressure piston and engageable thereby in said limiting positions thereof, said body being formed with a fitting perpendicular to said bore and to said pistons and communicating with said bore while receiving said ball, said switch means including a switch threaded into said fitting, a plate bearing on said ball and spaced from said switch, a compression spring against said plates and said switch under precompression, and a tappet connecting said plate with said switch for actuating same.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |