US3719102A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for hydraulic clutches of reversible gear-shift mechanism
Assignee: ZF Friedrichshafen AG
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Filing: 1972-02-28
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Granted: 1973-03-06
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Expires: 1992-02-28
Abstract
Abstract A hydraulic gear-shift mechanism for an automotive vehicle includes several gear clutches for the establishment of different speed ratios and a pair of directional clutches for choosing between forward and reverse drive. Both sets of clutches are actuatable by way of a pressure-responsive throttle valve, via respective selectors, yet in the neutral position of the directional selector a bypass is opened for the direct actuation of a selected gear clutch at high pressure. The closing of the bypass is controlled, in response to the back pressure from either directional clutch, by a blocking piston in a cylinder also containing a switching piston which responds to the same back pressure to direct supplemental oil from a branch of the bypass to the actuated directional clutch in order to compensate for leakage losses.
Inventors
- 👤 F Leber
- 👤 K Seumel
- 👤 G Mohrle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:07
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/02; F16H61/0262; F16H61/0265; F16H61/0272; F16H61/04; F16H61/06; F16H61/065; Y; Y10; Y10T; Y10T74/00; Y10T74/19; Y10T74/19219; Y10T74/19377; Y10T74/19414; Y10T74/19419; Y10T74/19423; Y10T74/19428; Y10T74/19433
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
176 words
In an automotive vehicle having traction wheels driven from an engine by way of a power train including a gear shifter provided with first hydraulic clutch means for the establishment of different speed ratios, second hydraulic clutch means for reversing the direction of locomotion, a source of high-pressure fluid for said clutch means, and first and second selector means each with a neutral position and a plurality of operating positions for respectively controlling said first and second clutch means, the combination therewith of: a pressure-responsive throttle valve in a fluid line between said source and said first and second clutch means; conduit means bypassing said throttle valve for establishing an alternate path between said source and one of said clutch means; and blocking means in said conduit means holding said path open in the neutral position of the selector means associated with the other of said clutch means, said blocking means being responsive to back pressure from said other of said clutch means in an operating position of the last-mentioned selector means for closing said path.
Claim 2
Dependent Claim
176 words
In an automotive vehicle having traction wheels driven from an engine by way of a power train including a gear shifter provided with first hydraulic clutch means for the establishment of different speed ratios, second hydraulic clutch means for reversing the direction of locomotion, a source of high-pressure fluid for said clutch means, and first and second selector means each with a neutral position and a plurality of operating positions for respectively controlling said first and second clutch means, the combination therewith of: a pressure-responsive throttle valve in a fluid line between said source and said first and second clutch means; conduit means bypassing said throttle valve for establishing an alternate path between said source and one of said clutch means; and blocking means in said conduit means holding said path open in the neutral position of the selector means associated with the other of said clutch means, said blocking means being responsive to back pressure from said other of said clutch means in an operating position of the last-mentioned selector means for closing said path.
Claim 3
Dependent Claim
176 words
In an automotive vehicle having traction wheels driven from an engine by way of a power train including a gear shifter provided with first hydraulic clutch means for the establishment of different speed ratios, second hydraulic clutch means for reversing the direction of locomotion, a source of high-pressure fluid for said clutch means, and first and second selector means each with a neutral position and a plurality of operating positions for respectively controlling said first and second clutch means, the combination therewith of: a pressure-responsive throttle valve in a fluid line between said source and said first and second clutch means; conduit means bypassing said throttle valve for establishing an alternate path between said source and one of said clutch means; and blocking means in said conduit means holding said path open in the neutral position of the selector means associated with the other of said clutch means, said blocking means being responsive to back pressure from said other of said clutch means in an operating position of the last-mentioned selector means for closing said path.
Claim 4
Dependent Claim
176 words
In an automotive vehicle having traction wheels driven from an engine by way of a power train including a gear shifter provided with first hydraulic clutch means for the establishment of different speed ratios, second hydraulic clutch means for reversing the direction of locomotion, a source of high-pressure fluid for said clutch means, and first and second selector means each with a neutral position and a plurality of operating positions for respectively controlling said first and second clutch means, the combination therewith of: a pressure-responsive throttle valve in a fluid line between said source and said first and second clutch means; conduit means bypassing said throttle valve for establishing an alternate path between said source and one of said clutch means; and blocking means in said conduit means holding said path open in the neutral position of the selector means associated with the other of said clutch means, said blocking means being responsive to back pressure from said other of said clutch means in an operating position of the last-mentioned selector means for closing said path.
Claim 5
Dependent Claim
18 words
The combination defined in claim 1 wherein said oTher of said clutch means is said second clutch means.
Claim 6
Dependent Claim
21 words
The combination defined in claim 2 wherein said blocking means comprises a hydraulic cylinder and a spring-loaded piston in said cylinder.
Claim 7
Dependent Claim
93 words
The combination defined in claim 3, further comprising a control piston in said cylinder aligned with said spring-loaded piston having a first land confronting a first fluid space and a second land confronting a face of said spring-loaded piston across a second fluid space, said second clutch means including a pair of clutches respectively communicating with said first and second fluid space via conduits connected to said fluid line by way of said throttle valve in respective operating positions of said second selector means for repressing said spring-loaded piston against its loading force.
Claim 8
Dependent Claim
39 words
The combination defined in claim 4, further comprising a branch line extending from said conduit means to said cylinder for feeding supplemental fluid to the clutch of said pair pressurized in an operating position of said second selector means.
Claim 9
Dependent Claim
25 words
The combination defined in claim 5 wherein branch line forms part of a restricted overflow circuit in the neutral position of said first selector means.
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) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |