US3872885A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressure failure switch
Assignee: DBA SA
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Filing: 1973-12-13
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Granted: 1975-03-25
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Expires: 1993-12-13
Abstract
Abstract The invention relates to a pressure imbalance detector for use in a vehicle hydraulic brake system having two separate subcircuits, wherein an electrical indicator device is activated if one of the brake sub-circuits fails. The indicator device includes an electrical switch actuated by a movable sleeve located between two pistons, each of which being responsive to the fluid pressure existing in one sub-circuits. The pistons have an annular shape for receiving fixed rods on which bear the ends of a resilient assembly. The resilient assembly which is located in the inner space of the sleeve has a spring inserted between two cups. Each cup is adapted to engage the adjacent rod and the corresponding piston.
Inventors
- 👤 Christian Eloi
- 👤 Christian Riquart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 03:20
CPC Classifications
B; B60; B60T; B60T17/00; B60T17/18; B60T17/22; B60T17/226; H; H01; H01H; H01H35/00; H01H35/24; H01H35/38; Y; Y10; Y10T; Y10T137/00; Y10T137/8158; Y10T137/8225; Y10T137/8242
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
129 words
Pressure imbalance detector comprising a housing with a bore therein, two annular pistons slidably mounted in said bore, the adjacents ends of the pistons being separated by a resilient system whereas the other ends of the pistons define in said bore two pressure chambers capable of being connecTed to two separate fluid circuits, rods fixed relative to said housing and sealingly projecting through said pistons, said rods being adapted to be engaged by the ends of the resilient system and switching means for closing an electrical circuit in the event of motion of the pistons due to a pressure difference denoting failure of one of the fluid circuits, said means for closing comprising a movable element mounted between the pistons and engaged thereby without interference with the resilient system.
Claim 2
Dependent Claim
129 words
Pressure imbalance detector comprising a housing with a bore therein, two annular pistons slidably mounted in said bore, the adjacents ends of the pistons being separated by a resilient system whereas the other ends of the pistons define in said bore two pressure chambers capable of being connecTed to two separate fluid circuits, rods fixed relative to said housing and sealingly projecting through said pistons, said rods being adapted to be engaged by the ends of the resilient system and switching means for closing an electrical circuit in the event of motion of the pistons due to a pressure difference denoting failure of one of the fluid circuits, said means for closing comprising a movable element mounted between the pistons and engaged thereby without interference with the resilient system.
Claim 3
Dependent Claim
36 words
Pressure imbalance detector as claimed in claim 1, wherein the resilient system comprises a spring bearing on the rods by way of circular members whose peripheries can be engaged by the pistons slidable on the rods.
Claim 4
Dependent Claim
21 words
Pressure imbalance detector as claimed in claim 2 wherein the rods are attached to plugs closing the ends of the bore.
Claim 5
Dependent Claim
28 words
An imbalance detector as claimed in claim 2, wherein respective projections on the rods adjoin one another, and the rods occupy substantially the entire length of the bore.
Claim 6
Dependent Claim
23 words
An imbalance detector as claimed in claim 1, wherein said movable element is a sleeve which does not interfere with the resilient system.
Claim 7
Dependent Claim
68 words
Pressure imbalance detector as claimed in claim 1, wherein the switching means comprise a metal plunger passing through the bore wall by way of an insulating duct so as to project into the space between the two pistons and make contact with the movable element, which comprises two conductive regions electrically connected to the housing earth, and located on each side of a region insulated from the earth.
Claim 8
Dependent Claim
22 words
Pressure imbalance detector as claimed in claim 6, wherein the movable element comprises a ring of insulating material between two metal rings.
Claim 9
Dependent Claim
49 words
Pressure imbalance detector as claimed in claim 1, wherein each piston comprises a rigid ring adjacent to the movable member and an O-ring seal adjacent to the associated pressure chamber and co-operating in a fluid tight manner with both the inside wall of the bore and the associated rod.
Claim 10
Dependent Claim
50 words
Pressure imbalance detector as claimed in claim 1 further comprising a short-circuiting orifice connected to the bore near one end thereof and communicating with the adjacent pressure chamber when the associated piston, termed the control piston, moves due to a pressure difference denoting a pressure drop in the other chamber.
Claim 11
Dependent Claim
80 words
Pressure imbalance detector as claimed in claim 9 wherein each piston comprises a rigid ring adjacent to the movable member and an O-ring seal adjacent to the associated pressure chamber and co-operating in a fluid tight manner with both the inside wall of the bore and the associated rod, said control piston comprising a second seal capable of cutting off the short-circuiting orifice from the space containing the resilient system, whatever the position of the control piston in the bore.
Claim 12
Dependent Claim
30 words
Pressure imbalance detector as claimed in claim 10, wherein the second seal is substantially identical to the O-ring seal and the two seals are separated by a rigid tubular spacer.
Claim 13
Dependent Claim
19 words
Pressure imbalance detector as claimed in claim 9 wherein the bore contains a chamfered annular groove opposite the orifice.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |