Patent US3917355A successfully refreshed from Google Patents.
US3917355A
Expired / Lapsed
US
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Fluid pressure control device with a failure alarm for a vehicle brake system
Assignee: Astemo Ltd
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Filing: 1975-02-19
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Granted: 1975-11-04
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Expires: 1995-02-19
Abstract
Abstract A device particularly designed to control the level of brake fluid pressure at the rear wheels relative to that at the front wheels so as to enable the brake system to operate with maximized efficiency despite of the forward tilt of the vehicle when braked. It includes, among others, a pair of pressure-reducing control valves inserted in the respective hydraulic fluid lines connected to the rear wheel brakes, a balance piston arranged across the fluid lines downstream of the control valves, and an alarm device associated with the balance piston. The balance piston is movable under a pressure differential, as occurring in the event of a fluid leak in either fluid line, to operate the associated alarm to warn the driver of such fluid failure without delay while enabling the full level of fluid pressure in the other, normal fluid line to reach the rear wheel, bypassing the control valve in the fluid line. If, when the brake pedal is released, one or the other of the control valves fail to restore its normal state to relieve the associated rear wheel brake of the hydraulic pressure previously applied, the balance piston is moved under such pressure again to produce an alarm signal and the brake fluid pressure is effectively released.
Inventors
- 👤 Hiroo Takeuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:56
CPC Classifications
B; B60; B60T; B60T17/00; B60T17/18; B60T17/22; B60T17/226; B60T11/00; B60T11/10; B60T11/28; B60T11/34; B60T8/00; B60T8/26
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
478 words
In a vehicle brake system of the type including a dual brake master cylinder having a first and a second independent output port (P1 and P2), a first and a second hydraulic fluid line (L1 and L2) extending from said respective first and second output ports, a pair of right and left front wheel brakes (Bf'' and Bf) having fluid chambers suitably connected with said first and second fluid lines, and a pair of right and left rear wheel brakes (Br'' and Br) having fluid chambers connected respectively with said first and second fluid lines, a fluid pressure control device with a failure alarm, comprising a common casing (3) arranged on said first and second fluid lines (L1 and L2) between said brake master cylinder and said rear wheel brakes (Br'' and Br) and defining a cylinder bore (4), a first and a second pressure-receiving piston (51 and 52) slidably fitted in said cylinder bore at the opposite ends thereof, a first and a second fluid chamber (71 and 72) defined on the outside of said respective pressure-receiving pistons and respectively communicating at all times with the upstream side of said first and second fluid lines (L1 and L2), a balance piston (9) slidably fitted in the mid-portion of said cylinder bore (4) so as to be normally held in a neutral position under the effect of said first and second pressure-receiving pistons (51 and 52), a third and a fourth fluid chamber (73 and 74) defined between the opposite ends of said balance piston (9) and said first and second pressure-receiving pistons (51 and 52) and respectively communicating at all times with the downstream side of said first and second fluid lines (L1 and L2), bypass holes (121 and 122) extending through said respective first and second pressurereceiving pistons (51 and 52) for fluid communication between said first and third fluid chambers (71 and 73) and between said second and fourthe fluid chambers (72 and 74), respectively, plug formations (111 and 112) on the opposite end faces of said balance piston (9) slidably fitted in said respective bypass holes (121 and 122) so that either of said bypass holes is opened with sliding movement of said balance piston (9) in a direction opposite to the bypass hole to an extreme position, a first and a second control valve (201 and 202) respectively arranged between said first and third fluid chambers (71 and 73) and between said second and foUrth fluid chambers (2 and 74) to allow fluid flow from said first and second fluid chambers, respectively, into said third and fourth fluid chambers while effecting a reduction in pressure at a predetermined ratio, and switch means arranged on said casing (3) and operable in response to sliding movement of said balance piston (9) in either direction from the neutral position thereof to actuate an external alarm (16).
Claim 2
Dependent Claim
478 words
In a vehicle brake system of the type including a dual brake master cylinder having a first and a second independent output port (P1 and P2), a first and a second hydraulic fluid line (L1 and L2) extending from said respective first and second output ports, a pair of right and left front wheel brakes (Bf'' and Bf) having fluid chambers suitably connected with said first and second fluid lines, and a pair of right and left rear wheel brakes (Br'' and Br) having fluid chambers connected respectively with said first and second fluid lines, a fluid pressure control device with a failure alarm, comprising a common casing (3) arranged on said first and second fluid lines (L1 and L2) between said brake master cylinder and said rear wheel brakes (Br'' and Br) and defining a cylinder bore (4), a first and a second pressure-receiving piston (51 and 52) slidably fitted in said cylinder bore at the opposite ends thereof, a first and a second fluid chamber (71 and 72) defined on the outside of said respective pressure-receiving pistons and respectively communicating at all times with the upstream side of said first and second fluid lines (L1 and L2), a balance piston (9) slidably fitted in the mid-portion of said cylinder bore (4) so as to be normally held in a neutral position under the effect of said first and second pressure-receiving pistons (51 and 52), a third and a fourth fluid chamber (73 and 74) defined between the opposite ends of said balance piston (9) and said first and second pressure-receiving pistons (51 and 52) and respectively communicating at all times with the downstream side of said first and second fluid lines (L1 and L2), bypass holes (121 and 122) extending through said respective first and second pressurereceiving pistons (51 and 52) for fluid communication between said first and third fluid chambers (71 and 73) and between said second and fourthe fluid chambers (72 and 74), respectively, plug formations (111 and 112) on the opposite end faces of said balance piston (9) slidably fitted in said respective bypass holes (121 and 122) so that either of said bypass holes is opened with sliding movement of said balance piston (9) in a direction opposite to the bypass hole to an extreme position, a first and a second control valve (201 and 202) respectively arranged between said first and third fluid chambers (71 and 73) and between said second and foUrth fluid chambers (2 and 74) to allow fluid flow from said first and second fluid chambers, respectively, into said third and fourth fluid chambers while effecting a reduction in pressure at a predetermined ratio, and switch means arranged on said casing (3) and operable in response to sliding movement of said balance piston (9) in either direction from the neutral position thereof to actuate an external alarm (16).
References Cited (Backward Citations)
US3841711A
Cited
US3672732A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-03 | 1979-05-05 | 1979-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-03 | 1983-05-05 | 1983-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-03 | 1987-05-05 | 1987-11-04 | $7700.00 | Window Closed / Lapsed |