Patent US3918765A successfully refreshed from Google Patents.
US3918765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressure control valve for vehicle braking system
Assignee: Tokico Ltd
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Filing: 1974-04-17
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Granted: 1975-11-11
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Expires: 1994-04-17
Abstract
Abstract A pressure control valve for use in a dual braking system of a vehicle comprising a pedal-actuated piston for transmitting hydraulic pressure to the large ends of two separate stepped pistons, wherein the small end of each of the stepped pistons cooperating with respective valve members for connecting a wheel cylinder selectively with a hydraulic reservoir and with a pressure source, and wherein an annular shoulder at the step of the stepped piston of one system is exposed to hydraulic pressure of the wheel cylinder of the other system which acts opposite to that of the pedalactuated piston.
Inventors
- 👤 Yoshihiro Hayashida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:51
CPC Classifications
B; B60; B60T; B60T17/00; B60T17/18; B60T17/22; B60T13/00; B60T13/10; B60T13/12; B60T13/14; B60T13/141
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
246 words
A pressure control valve for use in a dual circuit braking system for a vehicle comprising: a valve body having two stepped bores therein, a stepped piston slidably received in each of said stepped bores, an annular space defined between each of the stepped bores and stepped pistons received in said stepped bores, a pressure space defined respectively in each of said bores, each pressure space being communicated with at least one wheel cylinder of one of said braking circuits, valve means disposed in each of said pressure spaces for selectively connecting each of said pressure spaces with a source of hydraulic fluid under pressure and with a reservoir, a positively actuated piston disposed in one of said stepped bores coaxially with one of said stepped pistons and defining a fluid space with said stepped bore and said stepped piston, said positively actuated piston adapted to pressurize hydraulic fluid confined in said fluid space, said stepped pistons each having an end exposed in each of said pressure spaces and axially slidable therein for engaging said valve means and for actuating said valve means to connect one of the pressure spaces with the source of hydraulic fluid under pressure, and a passage permanently connecting one of the pressure spaces in one of said stepped bores to the annular space in the other stepped bore, to cause increased pressure in said one of the pressure spaces in response to decreased pressure in the other of said pressure spaces.
Claim 2
Dependent Claim
246 words
A pressure control valve for use in a dual circuit braking system for a vehicle comprising: a valve body having two stepped bores therein, a stepped piston slidably received in each of said stepped bores, an annular space defined between each of the stepped bores and stepped pistons received in said stepped bores, a pressure space defined respectively in each of said bores, each pressure space being communicated with at least one wheel cylinder of one of said braking circuits, valve means disposed in each of said pressure spaces for selectively connecting each of said pressure spaces with a source of hydraulic fluid under pressure and with a reservoir, a positively actuated piston disposed in one of said stepped bores coaxially with one of said stepped pistons and defining a fluid space with said stepped bore and said stepped piston, said positively actuated piston adapted to pressurize hydraulic fluid confined in said fluid space, said stepped pistons each having an end exposed in each of said pressure spaces and axially slidable therein for engaging said valve means and for actuating said valve means to connect one of the pressure spaces with the source of hydraulic fluid under pressure, and a passage permanently connecting one of the pressure spaces in one of said stepped bores to the annular space in the other stepped bore, to cause increased pressure in said one of the pressure spaces in response to decreased pressure in the other of said pressure spaces.
Claim 3
Dependent Claim
27 words
A pressure control valve as set forth in claim 1 wherein the diameter of said positively actuated piston is larger than the diameter of the stepped pistons.
Claim 4
Dependent Claim
38 words
A pressure control valve as set forth in claim 2 wherein one end of the positively actuated piston is formed to have a protruding end which is spaced from the stepped piston when in a normal operating condition.
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) | 1978-11-10 | 1979-05-12 | 1979-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-10 | 1983-05-12 | 1983-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-10 | 1987-05-12 | 1987-11-11 | $7700.00 | Window Closed / Lapsed |