US4355547A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuously variable ratio transmission
Assignee: Rover Co Ltd
•
Filing: 1979-05-30
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Granted: 1982-10-26
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Expires: 1999-05-30
Abstract
Abstract A continuously variable ratio transmission of the rolling friction type has a hydraulic control circuit including an end loading device for the transmission located upstream of a double sided piston used to balance roller reaction torque, and a valve for controlling the force exerted by the double sided piston. The valve has two outlets each feeding one side of the piston and communicating with the transmission's sump by way of a device for equalizing the flow rates from the two outlets to the sump. A feedback arrangement provides that the force exerted on the spool of the control valve is always proportional to the force exerted by the piston. The piston travel is limited by hydraulic end stops, upstream of which is provided a pressure relief valve to eliminate damaging transient overloads being exerted by the end loading device. The circuit also includes a facility whereby normal electrical/electronic control of the control valve can be overridden in an emergency.
Inventors
- 👤 Joseph J. Poole
- 👤 Victor E. Strange
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:24
CPC Classifications
F; F16; F16H; F16H37/00; F16H37/02; F16H37/06; F16H37/08; F16H37/0833; F16H37/084; F16H37/086; F16H15/00; F16H15/02; F16H15/04; F16H15/06; F16H15/32; F16H15/36; F16H15/38; F16H61/00; F16H61/66; F16H61/664; F16H61/6648; F16H2015/383; F16H2037/088; F16H2037/0886; F16H61/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
121 words
A continuously variable ratio transmission of the rolling friction type including a plurality of tiltable rollers and a hydraulic circuit for controlling the tilt angle of said rollers, said control circuit comprising: a source of pressurized fluid; a valve means; a sink for said fluid; a pair of outlets from said valve means for conveying fluid to said sink; a flow restriction means for restricting fluid flow from each of said outlets to said sink; and means operative in response to pressure difference in the fluid in said outlets for providing a force to balance roller torque reaction; said valve means being arranged to have an actuating force which is proportional to said pressure difference, at least under steady state conditions.
Claim 2
Dependent Claim
121 words
A continuously variable ratio transmission of the rolling friction type including a plurality of tiltable rollers and a hydraulic circuit for controlling the tilt angle of said rollers, said control circuit comprising: a source of pressurized fluid; a valve means; a sink for said fluid; a pair of outlets from said valve means for conveying fluid to said sink; a flow restriction means for restricting fluid flow from each of said outlets to said sink; and means operative in response to pressure difference in the fluid in said outlets for providing a force to balance roller torque reaction; said valve means being arranged to have an actuating force which is proportional to said pressure difference, at least under steady state conditions.
Claim 3
Dependent Claim
27 words
A transmission as claimed in claim 1, wherein said flow restriction means include means for ensuring equal flow rates through each of said restrictions to said sink.
Claim 4
Dependent Claim
23 words
A transmission as claimed in claim 2, wherein said means for ensuring equal flow rates includes an orifice of variable flow cross-sectional area.
Claim 5
Dependent Claim
28 words
A transmission as claimed in claim 1, including means for ensuring that pressure immediately downstream of said flow restriction means is kept at or above a datum pressure.
Claim 6
Dependent Claim
27 words
A transmission as claimed in claim 1, including flow control means for ensuring that the flow rate of fluid passing through said valve means remains substantially constant.
Claim 7
Dependent Claim
25 words
A transmission as claimed in claim 5, wherein said source comprises a pump driven at a speed proportional to the input speed of the transmission.
Claim 8
Dependent Claim
25 words
A transmission as claimed in claim 1, including an electro-magnetic means and an electronic logic circuit controlling said electro-magnetic means, for controlling said valve means.
Claim 9
Dependent Claim
106 words
A continuously variable ratio transmission of the rolling friction type having a plurality of tiltable rollers and a hydraulic circuit for controlling the tilt angle of said rollers, said control circuit comprising: a source of pressurized fluid; means operable by fluid pressure for providing a force to balance roller torque reaction; hydraulic end stop means associated with said roller torque reaction balancing means, whereby to limit the tilt angle of said rollers; end loading means located upstream of said end stop means for providing a reaction force between the rolling components; and means for attenuating peak pressures in the fluid upstream of said end stop means.
Claim 10
Dependent Claim
106 words
A continuously variable ratio transmission of the rolling friction type having a plurality of tiltable rollers and a hydraulic circuit for controlling the tilt angle of said rollers, said control circuit comprising: a source of pressurized fluid; means operable by fluid pressure for providing a force to balance roller torque reaction; hydraulic end stop means associated with said roller torque reaction balancing means, whereby to limit the tilt angle of said rollers; end loading means located upstream of said end stop means for providing a reaction force between the rolling components; and means for attenuating peak pressures in the fluid upstream of said end stop means.
Claim 11
Dependent Claim
16 words
A transmission as claimed in claim 8, wherein said attenuating means comprises a pressure relief valve.
Claim 12
Dependent Claim
15 words
A transmission as claimed in claim 8, wherein said attenuating means comprises a shock alleviator.
Claim 13
Dependent Claim
17 words
A transmission as claimed in claim 10, wherein said shock alleviator includes a reservoir of compressible fluid.
Claim 14
Dependent Claim
27 words
A transmission as claimed in claim 8, including means for maintaining fluid in said circuit downstream of said end stop means at or above a datum pressure.
Claim 15
Dependent Claim
80 words
A continuously variable ratio transmission of the rolling friction type, having a plurality of tiltable rollers and a hydraulic control circuit including: a source of pressurized fluid; means operable by fluid pressure for producing a force to balance roller torque reaction; valve means for controlling fluid flow to said roller torque reaction balancing means; and emergency override means for overriding electrical control of said valve means and for effecting operation of said valve means by fluid pressure from said source.
Claim 16
Dependent Claim
80 words
A continuously variable ratio transmission of the rolling friction type, having a plurality of tiltable rollers and a hydraulic control circuit including: a source of pressurized fluid; means operable by fluid pressure for producing a force to balance roller torque reaction; valve means for controlling fluid flow to said roller torque reaction balancing means; and emergency override means for overriding electrical control of said valve means and for effecting operation of said valve means by fluid pressure from said source.
Claim 17
Dependent Claim
52 words
A transmission as claimed in claim 13, further comprising an epi-cyclic gearset coupled to the rolling components in such manner as to permit selective operation in any one of a plurality of regimes, wherein said override means operate to override the regime selection controls to retain the transmission in a predetermined regime.
Claim 18
Dependent Claim
26 words
A transmission as claimed in claim 13, wherein said override means actuates said valve means by a resiliently biased piston-cylinder unit in communication with said source.
Claim 19
Dependent Claim
34 words
A transmission as claimed in claim 13, wherein said roller torque reaction balancing means include a double-sided piston, and wherein said override means operate to connect one side of said piston to base pressure.
Claim 20
Dependent Claim
33 words
A continuously variable ratio transmission as claimed in claim 13, or 15, wherein said override means apply to said valve means a biasing force variable proportionally with the input speed of the transmission.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-25 | 1986-04-26 | 1986-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-25 | 1990-04-26 | 1990-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-25 | 1994-04-26 | 1994-10-26 | $7700.00 | Window Closed / Lapsed |