US3580112A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic gear-shift control for automotive transmission system
Assignee: ZF Friedrichshafen AG
•
Filing: 1969-04-21
•
Granted: 1971-05-25
•
Expires: 1989-04-21
Abstract
Abstract A throttle valve 40 connected to a supply of hydraulic fluid delivers a variable fluid pressure dependent on the engine load of an automotive vehicle whose accelerator controls a plunger 42 which, through the intermediary of a compression spring 43, resists the displacement of the body 41 of that valve in response to the supply pressure. In a retracted or partly depressed position of the accelerator, the plunger 42 blocks the transmission of the load-dependent fluid pressure via a first conduit 220 to an automatic switching device 90 having a control piston 91 acted upon by speed-dependent fluid pressure and biased by a countervailing spring 105 into a normal, low-speed position. In the absence of supplemental fluid pressure from the throttle valve 40, the control piston 91 together with an associated slider 98 is moved into an off-normal, high-speed position whenever the speed-dependent fluid pressure overcomes the force of the biasing spring 105; with the accelerator in a position approaching full throttle, i.e. beyond a predetermined load threshold, the biasing force is supplemented by the loaddependent fluid pressure so that upshifting occurs at higher drive shaft speeds only. The load-dependent fluid pressure is applied in aiding relationship via two branch conduits 220a, 220d to a face of the piston and to another face on the slider, the first branch conduit 220a being obstructed in the off-normal piston position so as to create a hysteresis effect whereby under unchanged load conditions the downshift takes place at a lower speed than the upshift. Another conduit 221, unblocked by the plunger 42 in a kick-down position of the accelerator, partly cancels the aforementioned hysteresis effect whereby downshift under maximum load occurs at a higher speed.
Inventors
- 👤 Hansjorg Dach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:19
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/02; F16H61/0262; F16H61/0276; F16H61/029; F16H59/00; F16H59/14; F16H59/18; F16H59/20
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
240 words
In an automotive transmission system connected betweEn a fuel-powered engine and an output shaft, including gear-shifting means for switching between a relatively low ratio and a relatively high ratio of output-shaft speed to engine speed and further including operator-controlled accelerator means for varying the fuel supply to said engine, the combination therewith of a source of first fluid pressure varying generally proportionally to said output-shaft speed; fluid-supply means coupled with said accelerator means for generating a second fluid pressure which remains substantially invariable between a retracted accelerator position corresponding to minimum engine load and an intermediate accelerator position corresponding to a predetermined load threshold, said second fluid pressure thereupon rising progressively with further advances of said accelerator beyond said intermediate position; and automatic switchover means for said gear-shifting means comprising a piston having a first face subjected to said first fluid pressure and an opposite second face subjected to said second fluid pressure, said switchover means further including biasing means opposed by said first fluid pressure and aided by said second fluid pressure tending to maintain said piston in a normal position in which said gear-shifting means maintains said relatively low ratio, said first fluid pressure tending to move said piston into an off-normal position in which said gear-shifting means maintains said relatively high ratio whereby upshifting occurs at a substantially invariable output-shaft speed with loads below said threshold and at progressively higher speeds with loads increasing beyond said threshold.
Claim 2
Dependent Claim
240 words
In an automotive transmission system connected betweEn a fuel-powered engine and an output shaft, including gear-shifting means for switching between a relatively low ratio and a relatively high ratio of output-shaft speed to engine speed and further including operator-controlled accelerator means for varying the fuel supply to said engine, the combination therewith of a source of first fluid pressure varying generally proportionally to said output-shaft speed; fluid-supply means coupled with said accelerator means for generating a second fluid pressure which remains substantially invariable between a retracted accelerator position corresponding to minimum engine load and an intermediate accelerator position corresponding to a predetermined load threshold, said second fluid pressure thereupon rising progressively with further advances of said accelerator beyond said intermediate position; and automatic switchover means for said gear-shifting means comprising a piston having a first face subjected to said first fluid pressure and an opposite second face subjected to said second fluid pressure, said switchover means further including biasing means opposed by said first fluid pressure and aided by said second fluid pressure tending to maintain said piston in a normal position in which said gear-shifting means maintains said relatively low ratio, said first fluid pressure tending to move said piston into an off-normal position in which said gear-shifting means maintains said relatively high ratio whereby upshifting occurs at a substantially invariable output-shaft speed with loads below said threshold and at progressively higher speeds with loads increasing beyond said threshold.
Claim 3
Dependent Claim
95 words
The combination defined in claim 1 wherein said fluid-supply means comprises a throttle valve with an inlet for high-pressure fluid and an outlet leading to said switchover means, a valve member shiftable by fluid pressure at said inlet from a relatively open position toward a relatively closed position, adjustable spring means bearing upon said valve member in a sense urging same toward said relatively open position whereby fluid pressure at said outlet varies generally in proportion to the stress of said spring means, and coupling means operatively connecting said spring means with said accelerator means.
Claim 4
Dependent Claim
46 words
The combination defined in claim 2 wherein said coupling means comprises a plunger interposed in the fluid path between said outlet and said switchover means for controlling the transmission of said second fluid pressure to said piston in dependence upon the position of said accelerator means.
Claim 5
Dependent Claim
76 words
The combination defined in claim 3 wherein said fluid path includes a split conduit with a first branch terminating at said second face of said piston and with a second branch terminating at a third face of said piston turned to the same side whereby the fluid pressures from said branches reinforce each other, said piston in its off-normal position blocking said first branch with a resulting hysteresis effect retarding the return to said normal position.
Claim 6
Dependent Claim
72 words
The combination defined in claim 4 wherein said accelerator means has a maximum-load position and a kick-down position beyond said maximum-load position, said fluid path further including an additional conduit controlled by said plunger for communication with said outlet together with said split conduit in said kick-down position, said additional conduit terminating at a location confronting said second face of said piston in the off-normal position thereof for reducing said hysteresis effect.
Claim 7
Dependent Claim
31 words
The combination defined in claim 3 wherein said plunger is disposed to block said fluid path in any position of said accelerator means between said retracted position and said intermediate position.
Claim 8
Dependent Claim
58 words
The combination defined in claim 6 wherein said piston has an extension with a pair of heads forming two confronting faces of different surface areas positioned to receive pressure fluid in said off-normal position with development of a differential force counteracting said biasing means, thereby giVing rise to a hysteresis effect retarding the return to said normal position.
Claim 9
Dependent Claim
134 words
The combination defined in claim 7 wherein said accelerator means has a maximum-load position and a kick-down position beyond said maximum-load position, said fluid path including a first conduit with one branch terminating at said second face of said piston and with another branch terminating at a third face of said piston turned to the same side whereby the fluid pressures from said branches reinforce each other, said piston in its off-normal position blocking said one branch with a resulting additional hysteresis effect further retarding the return to said normal position, said fluid path including a second conduit unblocked by said plunger jointly with said first conduit only in said kick-down position and terminating at a location confronting said second face in the off-normal position of said piston for reducing said additional hysteresis effect.
Claim 10
Dependent Claim
22 words
The combination defined in claim 3 wherein said coupling means further comprises a lost-motion connection between said plunger and said spring 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) | 1974-05-24 | 1974-11-23 | 1975-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-24 | 1978-11-23 | 1979-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-24 | 1982-11-23 | 1983-05-25 | $7700.00 | Window Closed / Lapsed |