US3908485A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic power transmission control system for reducing shocks when shifting from neutral to reverse drive conditions
Assignee: Nissan Motor Co Ltd
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Filing: 1974-08-08
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Granted: 1975-09-30
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Expires: 1994-08-08
Abstract
Abstract Improvement is made in a hydraulic control system of an automatic power transmission for an automotive vehicle so as to lessen shocks which are produced during a shift from the neutral to the reverse drive condition. The line pressure in the control system is reduced in response to idling condition of the engine during the reverse drive condition of the vehicle.
Inventors
- 👤 Toshiyuki Miyauchi
- 👤 Kunio Ohtsuka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:03
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/02; F16H61/0202; F16H61/0251; F16H2061/026; F16H2061/0485; F16H59/00; F16H59/14; F16H59/18; F16H59/22; F16H61/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
354 words
An automatic power transmission which consists of a transmission mechanism for selectively producing any of a multiplicity of forward-speed gear ratios and a reverse-speed gear ratio and a hydraulic control system for hydraulically controlling the transmission mechanism, the hydraulic control system comprising a source of line pressure, a throttle valve responsive to load on an engine connected to the transmission mechanism for producing from the line pressure a throttle pressure which varies with the engine load, a governor valve responsive to vehicle speed for producing from the line pressure a basic governor pressure which varies with the vehicle speed, a hysteresis valve for producing from the line pressure a substantially constant hysteresis pressure which is higher than the governor pressure, a pressure regulaTor valve which has a first fluid port constantly in communication with the source of the line pressure, a second fluid port for being open to communicate with the source of the line pressure during forward drive condition of the vehicle, a third fluid port which is in constant communication with the throttle valve and a fourth fluid port to selectively communicating with the source of the line pressure or the hysteresis valve over a first tow-position valve which is operative to pass therethrough the line pressure in the presence of the line pressure therein during the forward drive condition or the hysteresis pressure in the absence of the line pressure therein, whereby the pressure regulator valve is acted upon by: the line pressure in the first, second and fourth fluid ports and the throttle pressure in the third fluid port for maintaining the line pressure at a first level during the forward drive condition of the vehicle; the line pressure in the first fluid port and the throttle pressure in the third fluid port during reverse drive condition of the vehicle; and the line pressure in the first fluid port, the throttle pressure in the third fluid port and the hysteresis pressure in the fourth fluid port for maintaining the line pressure at a second level lower than the first level during idling under the reverse drive condition of the vehicle.
Claim 2
Dependent Claim
354 words
An automatic power transmission which consists of a transmission mechanism for selectively producing any of a multiplicity of forward-speed gear ratios and a reverse-speed gear ratio and a hydraulic control system for hydraulically controlling the transmission mechanism, the hydraulic control system comprising a source of line pressure, a throttle valve responsive to load on an engine connected to the transmission mechanism for producing from the line pressure a throttle pressure which varies with the engine load, a governor valve responsive to vehicle speed for producing from the line pressure a basic governor pressure which varies with the vehicle speed, a hysteresis valve for producing from the line pressure a substantially constant hysteresis pressure which is higher than the governor pressure, a pressure regulaTor valve which has a first fluid port constantly in communication with the source of the line pressure, a second fluid port for being open to communicate with the source of the line pressure during forward drive condition of the vehicle, a third fluid port which is in constant communication with the throttle valve and a fourth fluid port to selectively communicating with the source of the line pressure or the hysteresis valve over a first tow-position valve which is operative to pass therethrough the line pressure in the presence of the line pressure therein during the forward drive condition or the hysteresis pressure in the absence of the line pressure therein, whereby the pressure regulator valve is acted upon by: the line pressure in the first, second and fourth fluid ports and the throttle pressure in the third fluid port for maintaining the line pressure at a first level during the forward drive condition of the vehicle; the line pressure in the first fluid port and the throttle pressure in the third fluid port during reverse drive condition of the vehicle; and the line pressure in the first fluid port, the throttle pressure in the third fluid port and the hysteresis pressure in the fourth fluid port for maintaining the line pressure at a second level lower than the first level during idling under the reverse drive condition of the vehicle.
Claim 3
Dependent Claim
62 words
An automatic power transmission as set forth in claim 1, in which said hydraulic control system further comprises a solenoid-operated control valve which is closed during open-throttle condition of the engine and which is responsive to idling condition of the engine for being open to provide the communication between the hysteresis valve and the fourth fluid port of the pressure regulator valve.
Claim 4
Dependent Claim
153 words
An automatic power transmission as set forth in claim 1, in which said hydraulic control system further comprises a solenoid-operated control valve and an idle valve, wherein the solenoid-operated control valve is operative to be closed during open-throttle condition excepting kick-down condition and is responsive to idling or kick-down condition of the engine for being open to provide communication between the hysteresis valve and the idle valve and wherein the idle valve is biased to open to provide communication between the solenoid-operated control valve and the fourth fluid port of the pressure regulator valve and, when the solenoid-operated control valve is open, between the hysteresis valve and the fourth fluid port of the regulator valve and is responsive to the throttle pressure for closing to block the communication between the solenoid-operated control valve and the fourth fluid port of the pressure regulator valve when the throttle pressure is higher than a predetermined level.
Claim 5
Dependent Claim
178 words
An automatic power transmission as set forth in claim 3, in which said hydraulic control system further comprises a plurality of shift valves each of which has a first fluid port communicating with the governor valve and the idle valve over a second two-position valve which is operative to pass therethrough the governor pressure in the absence of the hysteresis pressure directed thereto or the hysteresis pressure in the presence of both the governor pressure and the hysteresis pressure therein for urging the shift valve toward its upshift position by either the governor pressure or the hysteresis pressure and a second fluid port which is in constant communication with the throttle valve for urging the shift valve toward its downshift position by the throttle pressure, whereby all the shift valves are brought into their respective upshift positions to provide direct drive condition in the transmission mechanism when the solenoid-operated control valve and the idle valve are concurrently open and the hysteresis pressure is directed through the second two-position valve to the first fluid ports of the shift valves.
Claim 6
Dependent Claim
143 words
An automatic power transmission as set forth in claim 4, in which said hydraulic control system furtheR comprises a throttle back-up valve having a first fluid port for being open to communicate with the source of the line pressure during the manual forward drive condition, a second fluid port which is in constant communication with the throttle valve, and a third fluid port which is in communication with the above-mentioned second fluid port and the idle valve for normally directing the throttle pressure to the idle valve, the third fluid port being brought into the first fluid port for directing the line pressure to the idle valve and thereby causing the idle valve to interrupt the communication between the idle valve and the first fluid port of each of the shift valves whereby the shift valves are brought into their respective downshift positions.
Claim 7
Dependent Claim
254 words
An automatic power transmission as set forth in claim 4, in which said hydraulic control system further comprises a kick-down valve having a first fluid port communicating over the solenoid-operated control valve with the hysteresis valve, a second fluid port which is in constant communication with the throttle pressure urging the kick-down valve toward an open condidtion, and a third fluid port to communicate with the abovementioned first fluid port when the kick-down valve is in the open condition for delivering the hysteresis pressure from the third fluid port when the solenoid-operated control valve is open and concurrently the throttle pressure in the second fluid port is higher than a certain level, and a downshift valve having a first fluid port for being open to communicate with the source of the line pressure, a second fluid port for being open to communicate with the governor valve, a third fluid port which is in constant communication with the third fluid port of the kick-down valve and a fourth fluid port which is in constant communication with the first fluid ports of the shift valves through said second two-position valve, the downshift valve being in a position to boost the governor pressure to be delivered from the fourth fluid port thereof in the absence of the hysteresis pressure in the third fluid port and a position to directly pass the governor pressure through the second and fourth fluid ports of the downshift valve in the presence of the hysteresis pressure in the third fluid port thereof.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |