US4524641A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuously-variable ratio-transmission
Assignee: BTG International Ltd
•
Filing: 1982-10-22
•
Granted: 1985-06-25
•
Expires: 2002-10-22
Abstract
Abstract Two piston and cylinders 13, 15 and 16, 18 control the force reaction of a roller mounting in a continuously-variable-ratio transmission of the rolling traction type. A pressure control valve 23 controls the net force on the roller mounting by controlling the relative pressure in two pressure lines which include the cylinders. A flow dividing valve 22 equalizes the flows in the lines by feedback across two identical orifices 26, 27. Excessive displacements of the roller mounting (which could cause the rollers to run off their toroidal races) are controlled by ports 19, 20, which are restricted at respective ends of the permissible movement. The restriction causes a pressure build up in the cylinder which resists that threatening the original overshoot, while restricting the effect of the pressure control valve by virtue of the action of the orifices 26, 27 and flow dividing valve 22, and this also reduces the pressure which originally threatened the overshoot.
Inventors
- 👤 Christopher J. Greenwood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 04:48
CPC Classifications
F; F16; F16H; F16H15/00; F16H15/02; F16H15/04; F16H15/06; F16H15/32; F16H15/36; F16H15/38; F16H2015/383; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/068; F16H61/66; F16H61/664
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
189 words
A continuously-variable ratio transmission of the rolling traction type having at least one pair of toroidally-recessed discs with rollers interposed on mountings therebetween, and having a hydraulic control circuit, said transmission comprising a pair of hydraulic rams for exerting forces on one of said roller mountings in two opposite directions to displace said rollers and to balance any roller reaction force; each of said hydraulic rams having a cylinder defining a working chamber and a head, said hydraulic control circuit including a hydraulic line passing through the working chamber of each of said hydraulic rams, there being two of said hydraulic lines, one hydraulic line for each of said hydraulic rams, means for varying pressure in each of said two hydraulic lines for producing said forces exerted on said one roller mounting; and each of said hydraulic rams having a hydraulic end stop arrangement operating when said one roller mounting approaches an end position to restrict the corresponding one of said hydraulic lines only, thereby to increase substantially the pressure within said one corresponding hydraulic line causing said forces strongly to resist further roller displacement towards said end position.
Claim 2
Dependent Claim
189 words
A continuously-variable ratio transmission of the rolling traction type having at least one pair of toroidally-recessed discs with rollers interposed on mountings therebetween, and having a hydraulic control circuit, said transmission comprising a pair of hydraulic rams for exerting forces on one of said roller mountings in two opposite directions to displace said rollers and to balance any roller reaction force; each of said hydraulic rams having a cylinder defining a working chamber and a head, said hydraulic control circuit including a hydraulic line passing through the working chamber of each of said hydraulic rams, there being two of said hydraulic lines, one hydraulic line for each of said hydraulic rams, means for varying pressure in each of said two hydraulic lines for producing said forces exerted on said one roller mounting; and each of said hydraulic rams having a hydraulic end stop arrangement operating when said one roller mounting approaches an end position to restrict the corresponding one of said hydraulic lines only, thereby to increase substantially the pressure within said one corresponding hydraulic line causing said forces strongly to resist further roller displacement towards said end position.
Claim 3
Dependent Claim
35 words
A transmission according to claim 1, wherein said pressure-varying means including flow means acting on said two hydraulic lines to insure substantially equal flow therethrough during both normal control operation and hydraulic end stop function.
Claim 4
Dependent Claim
53 words
A transmission as claimed in claim 1 wherein there is an outlet in each ram working chamber which is at least partially closed by said hydraulic ram head at the respective extremities of movement of said one roller mounting, thereby causing said restrictions in said hydraulic lines for the hydraulic end stop operation.
Claim 5
Dependent Claim
40 words
A transmission as claimed in claim 3, wherein the dimensions of said ram chambers and said ram heads are such that said ram chambers at least partially exhaust by permitting fluid flow across said ram heads at said respective extremities.
Claim 6
Dependent Claim
54 words
A transmission as claimed in claim 4, wherein said outlets open into grooves extending around walls of said ram chambers in a circumferential direction, said grooves being of a length of axial direction equal to or greater than the lengths of said ram heads, to permit the said fluid flow across said ram heads.
Claim 7
Dependent Claim
34 words
A transmission according to claim 1, wherein each ram head carries a coaxial piston which is so sized relative to a respective cylinder in which it travels to provide damping for said hydraulic ram.
Claim 8
Dependent Claim
64 words
A transmission according to claim 1, wherein there are other pairs of hydraulic rams for mounting of others of said rollers acting between said toroidal recessed discs, said other pairs of hydraulic rams also having working chambers, and said working chambers of said hydraulic rams for said one roller mounting being in communication with said working chambers of said other pairs of hydraulic rams.
Claim 9
Dependent Claim
62 words
A transmission as claimed in claim 7, wherein there are two pairs of toroidal-recessed discs facing each other with rollers interposed therebetween, said pairs of toroidal-recessed discs reacting against each other, said working chambers of said hydraulic rams of the first mentioned roller mounting being in communication with working chambers of the corresponding hydraulic rams for all of the other roller mountings.
Claim 10
Dependent Claim
36 words
A transmission according to claim 1, wherein said means for varying pressure in each of said two hydraulic lines includes valve means downstream of said hydraulic rams to provide a variable restriction in each hydraulic line.
Claim 11
Dependent Claim
36 words
A transmission according to claim 2, wherein said means for varying pressure in each of said two hydraulic lines includes valve means downstream of said hydraulic rams to provide a variable restriction in each hydraulic line.
Claim 12
Dependent Claim
40 words
A transmission according to claim 10, wherein said flow means include flow dividing means arranged upstream of said hydraulic rams for maintaining substantially equal division of an input flow between two said hydraulic lines as said valve means is varied.
Claim 13
Dependent Claim
41 words
A transmission according to claim 11 wherein said flow dividing means is arranged to equalize fluid flow through each hydraulic line by sensing pressure differences across identical orifices arranged in said hydraulic lines between said hydraulic rams and said valve means.
Claim 14
Dependent Claim
51 words
A transmission according to claim 12, wherein said flow dividing means includes a valve having a valve member movable to restrict one of two ports connected by said hydraulic lines to said hydraulic rams, and said valve member being subject to fluid pressures on each side of both of said orifices.
Claim 15
Dependent Claim
42 words
A transmission according to claim 13, wherein said valve means include a single valve, and pressure difference in said hydraulic lines being fed back to said valve member of said flow dividing means valve by virtue of lands on said valve member.
Claim 16
Dependent Claim
28 words
A transmission according to claim 11, together with a flow control valve for insuring constant flow to said flow dividing means by monitoring pressure drop across an orifice.
Claim 17
Dependent Claim
24 words
A transmission according to claim 1, wherein the each pair of hydraulic rams are integral with respective roller mountings without any intermediate mechanical linkage.
References Cited (Backward Citations)
US3570317A
Cited
US3739658A
Cited
US3826147A
Cited
US3826148A
Cited
US3828618A
Cited
US3823613A
Cited
US4186616A
Cited
GB2023573A
Cited
US4272999A
Cited
EP0006690A1
Cited
US4275610A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-24 | 1988-12-24 | 1989-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-24 | 1992-12-24 | 1993-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-24 | 1996-12-24 | 1997-06-25 | $7700.00 | Window Closed / Lapsed |