Patent US4772249A successfully refreshed from Google Patents.
US4772249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic control system for continuously variable transmission for automotive vehicle
Assignee: Toyota Motor Corp
•
Filing: 1987-02-19
•
Granted: 1988-09-20
•
Expires: 2007-02-19
Abstract
Abstract A hydraulic control system for a continuously variable transmission for an automotive vehicle, the transmission having a first and a second variable-diameter pulley provided on respective first and second shafts, a belt connecting the first and second pulleys, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys. The control system includes a shift-control valve receiving a first line pressure from said pressure source to one of the cylinders, while simultaneously permitting a flow of the fluid from the other cylinder. A second pressure line is connected to the shift-control valve to receive therefrom a pressure of the fluid flowing from above-indicated other cylinder. A pressure regulating valve regulates the pressure in the second pressure line, as a second line pressure lower than said first line pressure. The control system further includes at least one one-way by-pass line or restricted by-pass line which connects the second pressure line to at least one of the two cylinders, respectively. Each by-pass line permits a flow of the fluid from the second pressure line to the corresponding cylinder, or a restricted flow of the fluid between the second pressure line and the hydraulic cylinder.
Inventors
- 👤 Katsumi Kouno
- 👤 Susumu Okawa
- 👤 Masami Sugaya
- 👤 Yoshinobu Soga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:01
CPC Classifications
B; B60; B60W; B60W30/00; B60W30/18; B60W10/00; B60W10/04; B60W10/10; B60W10/101; B60W30/1819; F; F16; F16H; F16H61/00; F16H61/66; F16H61/662; F16H61/66254; F16H61/66259; F16H61/0021
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
250 words
A hydraulic control system for a continuously variable transmission of a belt-and-pulley type for an automotive vehicle, the transmission having a first and a second shaft, a first and a second variable-diameter pulley provided on the first and second shafts, respectively, a transmission belt connecting the first and second pulleys to transmit power from one of the pulleys to the other, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys, said hydraulic control system comprising: a hydraulic pressure source for pressurizing a working fluid; a shift-control valve receiving a first line pressure from said pressure source through a first pressure line, and applying said first line pressure to one of said first and second hydraulic cylinders, while simultaneously permitting a flow of the fluid from the other hydraulic cylinder, thereby changing the effective diameters of said first and second pulleys to control a speed ratio of said transmission; a second pressure line connected to said shift-control valve to receive therefrom a pressure of the fluid flowing from said other hydraulic cylinder; a pressure regulating valve for regulating the pressure in said second pressure line, as a second line pressure lower than said first pressure; and at least one restricted by-pass line connecting said second pressure line to at least one of said first and second hydraulic cylinders, respectively, said at least one restricted by-pass line permitting a restricted flow between said second pressure line and said at least one hydraulic cylinder.
Claim 2
Dependent Claim
250 words
A hydraulic control system for a continuously variable transmission of a belt-and-pulley type for an automotive vehicle, the transmission having a first and a second shaft, a first and a second variable-diameter pulley provided on the first and second shafts, respectively, a transmission belt connecting the first and second pulleys to transmit power from one of the pulleys to the other, and a first and a second hydraulic cylinder for changing effective diameters of the first and second pulleys, said hydraulic control system comprising: a hydraulic pressure source for pressurizing a working fluid; a shift-control valve receiving a first line pressure from said pressure source through a first pressure line, and applying said first line pressure to one of said first and second hydraulic cylinders, while simultaneously permitting a flow of the fluid from the other hydraulic cylinder, thereby changing the effective diameters of said first and second pulleys to control a speed ratio of said transmission; a second pressure line connected to said shift-control valve to receive therefrom a pressure of the fluid flowing from said other hydraulic cylinder; a pressure regulating valve for regulating the pressure in said second pressure line, as a second line pressure lower than said first pressure; and at least one restricted by-pass line connecting said second pressure line to at least one of said first and second hydraulic cylinders, respectively, said at least one restricted by-pass line permitting a restricted flow between said second pressure line and said at least one hydraulic cylinder.
Claim 3
Dependent Claim
41 words
A hydraulic control system according to claim 1, wherein said shift-control valve comprises a valve body having a bore, and a valve spool slidably received within said bore, said at least one restricted by-pass line being formed in said valve body.
Claim 4
Dependent Claim
41 words
A hydraulic control system according to claim 1, wherein said shift-control valve comprises a valve body having a bore, and a valve spool slidably received within said bore, said at least one restricted by-pass line being formed in said valve spool.
Claim 5
Dependent Claim
62 words
A hydraulic control system according to claim 1, wherein said shift-control valve comprises a valve body having a bore, and a valve spool slidably received within said bore, each of said at least one restricted by-pass line consists of a restrictor in the form of a radial clearance between said valve spool and a surface of said valve body defining said bore.
References Cited (Backward Citations)
US3600960A
Cited
DE2703487A1
Cited
JPS5298861A
Cited
DE2946295A1
Cited
EP0063786B1
Cited
JPS5829424A
Cited
US4557706A
Cited
US4628773A
Cited
US4669336A
Cited
EP0151535A1
Cited
US4627313A
Cited
EP0168540A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |