US3844121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple stage master cylinder
Assignee: Eaton Corp
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Filing: 1973-02-16
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Granted: 1974-10-29
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Expires: 1993-02-16
Abstract
Abstract A master cylinder for a vehicle brake incorporating separate filling and braking pressure stages, the filling stage employing a relatively large diameter piston with short pedal stroke and the braking stage employing a relatively smaller diameter piston with a relatively longer stroke. A clutching stage operable during the filling stage provides single pedal clutch and brake actuation for inching operations. One embodiment provides integral braking, filling and clutching stages with mechanical actuation of the filling stage, while an alternative embodiment provides a separate filling stage with hydraulic actuation.
Inventors
- 👤 K Griesenbrock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:43
CPC Classifications
B; B60; B60T; B60T11/00; B60T11/10; B60T11/103; B60T11/16; B60T11/224
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
245 words
A hydraulic braking and clutching system comprising a hydraulic pressure cylinder, a first chamber formed in said cylinder, a first gallery communicating said first chamber with a fluid reservoir, a second gallery communicating with at least one wheel brake cylinder for pressurizing said cylinder, a third gallery communicating said first chamber with said wheel cylinder for return flow to said first chamber, a first piston linearly movable within said first chamber between a first inoperative position to a second position in which said first chamber is pressurized, a second chamber formed in said cylinder, a fourth gallery communicating said second chamber with said fluid reservoir, a fifth gallery communicating said second chamber with a clutch slave cylinder, a valve member linearly movable within said second chamber between a first inoperative position and a second position in which said second chamber is pressurized, a second pressure cylinder, a third chamber formed within said second cylinder, a first gallery communicating said third chamber with said reservoir, a second gallery communicating said third chamber with said wheel cylinder, a second piston linearly movable within said third chamber between a first inoperative position and a second position in which said third chamber is pressurized, pressure limiting means within said third chamber for limiting the pressurization of said third chamber to a predetermined maximum, and means operatively connected to said valve member for moving said second piston from said first to said second position upon movement of said valve member.
Claim 2
Dependent Claim
245 words
A hydraulic braking and clutching system comprising a hydraulic pressure cylinder, a first chamber formed in said cylinder, a first gallery communicating said first chamber with a fluid reservoir, a second gallery communicating with at least one wheel brake cylinder for pressurizing said cylinder, a third gallery communicating said first chamber with said wheel cylinder for return flow to said first chamber, a first piston linearly movable within said first chamber between a first inoperative position to a second position in which said first chamber is pressurized, a second chamber formed in said cylinder, a fourth gallery communicating said second chamber with said fluid reservoir, a fifth gallery communicating said second chamber with a clutch slave cylinder, a valve member linearly movable within said second chamber between a first inoperative position and a second position in which said second chamber is pressurized, a second pressure cylinder, a third chamber formed within said second cylinder, a first gallery communicating said third chamber with said reservoir, a second gallery communicating said third chamber with said wheel cylinder, a second piston linearly movable within said third chamber between a first inoperative position and a second position in which said third chamber is pressurized, pressure limiting means within said third chamber for limiting the pressurization of said third chamber to a predetermined maximum, and means operatively connected to said valve member for moving said second piston from said first to said second position upon movement of said valve member.
Claim 3
Dependent Claim
54 words
APparatus as claimed in claim 1 including means for moving said first piston from said inoperative to said operative position, the pressurization of said first chamber resulting in movement of said valve member from said inoperative to said operative position and corresponding movement of said second piston from said first to said second position.
Claim 4
Dependent Claim
25 words
Apparatus as claimed in claim 1, in which said means operatively connected to said valve member comprises a mechanical link engageable with said second piston.
Claim 5
Dependent Claim
26 words
Apparatus as claimed in claim 1 in which said means operatively connected to said valve member comprises a hydraulic connection between said second and third chambers.
Claim 6
Dependent Claim
57 words
Apparatus as claimed in claim 1 in which said pressure limiting means comprises means defining a return flow path from said third chamber to said reservoir, a normally closed valve member within said return flow path, and means maintaining said valve member in said normally closed position until a predetermined pressure is obtained in said third chamber.
Claim 7
Dependent Claim
47 words
Apparatus as claimed in claim 5 including mechanical stop means within said third chamber, said mechanical stop means being engageable with said pressure limiting valve means to open said return flow path upon predetermined movement of said second piston from said inoperative position toward said operative position.
Claim 8
Dependent Claim
133 words
A master cylinder for a hydraulic vehicle brake comprising a filling stage including a pressure chamber and piston and incorporating a short operating stroke with a large displacement of hydraulic fluid, a braking stage including a pressure chamber and piston and incorporating a small displacement of hydraulic fluid relative to the filling stage, a clutch stage including a pressure chamber and control valve actuated upon movement of the braking stage piston for operating a clutch-actuating slave cylinder, and a valve element separating the pressure chamber of said braking stage from the pressure chamber of said clutch stage, said filling stage being operable by means associated with said clutch stage, said clutch stage being operable during the filling stage, and said braking stage becoming operable after the end of said filling and clutch stages.
Claim 9
Dependent Claim
133 words
A master cylinder for a hydraulic vehicle brake comprising a filling stage including a pressure chamber and piston and incorporating a short operating stroke with a large displacement of hydraulic fluid, a braking stage including a pressure chamber and piston and incorporating a small displacement of hydraulic fluid relative to the filling stage, a clutch stage including a pressure chamber and control valve actuated upon movement of the braking stage piston for operating a clutch-actuating slave cylinder, and a valve element separating the pressure chamber of said braking stage from the pressure chamber of said clutch stage, said filling stage being operable by means associated with said clutch stage, said clutch stage being operable during the filling stage, and said braking stage becoming operable after the end of said filling and clutch stages.
Claim 10
Dependent Claim
21 words
Apparatus as claimed in claim 7, in which said filling stage is operably associated with said clutching stage by mechanical means.
Claim 11
Dependent Claim
21 words
Apparatus as claimed in claim 7, in which said filling stage is operably associated with said clutching stage by hydraulic means.
Claim 12
Dependent Claim
23 words
Apparatus as claimed in claim 7 in which said filling stage includes pressure limiting means adjustable to correspond to the brake restoring force.
Claim 13
Dependent Claim
31 words
Apparatus as claimed in claim 10, including a filling piston within said filling stage, and including means for mechanically opening said pressure limiting means after predetermined movement of said filling piston.
Claim 14
Dependent Claim
20 words
Apparatus as claimed in claim 11 in which said pressure limiting means comprises valve means contained within said filling piston.
Claim 15
Dependent Claim
21 words
Apparatus as claimed in claim 7, including means for returning hydraulic fluid to said braking stage when the brake is released.
Claim 16
Dependent Claim
15 words
Apparatus as claimed in claim 13 including a throttle valve in said return flow line.
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) | 1977-10-28 | 1978-04-29 | 1978-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-28 | 1982-04-29 | 1982-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-28 | 1986-04-29 | 1986-10-29 | $7700.00 | Window Closed / Lapsed |