Patent US5129033A successfully refreshed from Google Patents.
US3682014A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Down-shifting transmission lock
Assignee: ZF Friedrichshafen AG
•
Filing: 1970-09-14
•
Granted: 1972-08-08
•
Expires: 1990-09-14
Abstract
Abstract A fluid-control transmission lock is provided to prevent unwanted downshifting of a multiple-speed transmission and especially a servocontrol or power-assist transmission. The lock is speed-responsive and prevents, for example, the spontaneous downshifting from one speed range to another or from a higher gear ratio within a particular range to an impermissibly lower gear ratio within that range, in accordance with the vehicle speed.
Inventors
- 👤 Alfred Magg
- 👤 Friedrich Schreiner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:52
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/16; F16H59/00; F16H59/36; F16H59/44; Y; Y10; Y10T; Y10T74/00; Y10T74/19; Y10T74/19219; Y10T74/19251; Y10T74/19256; Y10T74/1926
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
122 words
A transmission system for a motor vehicle, comprising: transmission means including gears defining a plurality of transmission speed sets, each with a plurality of particular transmission speeds; a speed-selector shaft operatively connected to said movable gears and axially shiftable to permit selection of one of a plurality of transmission speed sets and rotatable to permit selection of a particular transmission speed of one of said sets; means responsive to the speed of the vehicle; transmission-locking means operatively connected to said means responsive to the speed of said vehicle and operatively connected to said shaft for restricting said axial displacement of said shaft to prevent down-shifting from a higher-speed set to a lower-speed set until the vehicle speed falls below a predetermined value.
Claim 2
Dependent Claim
122 words
A transmission system for a motor vehicle, comprising: transmission means including gears defining a plurality of transmission speed sets, each with a plurality of particular transmission speeds; a speed-selector shaft operatively connected to said movable gears and axially shiftable to permit selection of one of a plurality of transmission speed sets and rotatable to permit selection of a particular transmission speed of one of said sets; means responsive to the speed of the vehicle; transmission-locking means operatively connected to said means responsive to the speed of said vehicle and operatively connected to said shaft for restricting said axial displacement of said shaft to prevent down-shifting from a higher-speed set to a lower-speed set until the vehicle speed falls below a predetermined value.
Claim 3
Dependent Claim
66 words
The system defined in claim 1 wherein said transmission-locking means includes a cylinder, a piston shiftable in said cylinder and connected with said shaft, a valve communicating between a source of power fluid and said cylinder and means for controlling said valve in response to the speed of the vehicle for permitting displacement of said piston within said cylinder upon a vehicle-speed decline below said value.
Claim 4
Dependent Claim
21 words
The system defined in claim 2 wherein said valve is provided with a biasing spring having a stress determining said value.
Claim 5
Dependent Claim
42 words
The system defined in claim 3 wherein said transmission means has a high-speed range and a low-speed range selective independently of the operation of said speed-selector shaft, said system further comprising means for adjusting the value in accordance with the effective range.
Claim 6
Dependent Claim
22 words
The system defined in claim 4 wherein the last mentioned means includes an adjusting motor for varying the stress of said spring.
Claim 7
Dependent Claim
65 words
The system defined in claim 4 wherein said means for controlling said valve in response to the speed of said vehicle includes a pump driven at a rate proportional to the vehicle speed, a throttle connected to the discharge Side of said pump, and a cylinder connected to said pump between said discharge side and said throttle and acting upon said valve opposite said spring.
Claim 8
Dependent Claim
70 words
The system defined in claim 1 wherein said transmission means includes a speed-changing mechanism operable independently of said shaft for establishing a high-speed range and a low-speed range, said system further comprising second transmission-locking means effective independently of the first mentioned transmission-locking means and operatively connected with said mechanism for restricting downshifting thereof from said high-speed range to said low-speed range until the vehicle speed falls below a predetermined value.
Claim 9
Dependent Claim
32 words
The system defined in claim 7 wherein said mechanism includes speed-changing gearing and a range-selection cylinder operatively connected to said gearing and energizable with a pressure fluid to select the speed range.
Claim 10
Dependent Claim
71 words
The system defined in claim 8 wherein said mechanism further comprises a main valve connected in a fluid path between a source of fluid under pressure and said cylinder, said shaft being provided with a rotatable cam and said valve having a cam follower engaging said cam for pressurization of said cylinder exclusively in a ''''neutral'''' position of said shaft corresponding to a position thereof intermediate speeds of the respective sets.
Claim 11
Dependent Claim
75 words
The system defined in claim 8 wherein said transmission-locking means includes a locking cylinder having a piston operatively connected to said shaft and axially shiftable therewith, a valve communicating between a source of pressure fluid and said locking cylinder, and means responsive to the vehicle speed for shifting said valve, said range-selection cylinder being connected to said valve for establishing the value at which downshifting from a higher-speed set to a lower-speed set is prevented.
Claim 12
Dependent Claim
51 words
The system defined in claim 8 wherein said second transmission-locking means includes a pilot valve actuatable by the vehicle operator, a relay valve connected with said pilot valve and communicating with said cylinder and a locking valve in fluid communication with said relay valve for controlledly restricting operation of said cylinder.
Claim 13
Dependent Claim
38 words
The system defined in claim 11 wherein said locking valve is provided with a biasing spring, said second transmission-locking means further comprising means responsive to the vehicle speed and acting upon said locking valve counter to said spring.
Claim 14
Dependent Claim
46 words
The system defined in claim 12 wherein the last mentioned means includes a pump driven at a rate proportional to the vehicle speed, a throttle connected to the discharge side of said pump and means connecting said discharge side of said pump with said locking valve.
Claim 15
Dependent Claim
47 words
The system defined in claim 12 wherein the last mentioned means includes a pulse generator driven at a rate proportional to said vehicle speed for producing an electrical-pulse train of a frequency proportional to vehicle speed and electromagnetic means connecting said pulse generator with said locking valve.
Claim 16
Dependent Claim
29 words
The system defined in claim 12 wherein said locking valve is interposed between said pilot valve and said relay valve for selectively preventing and permitting operation of the latter.
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) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |