Patent US3748926A successfully refreshed from Google Patents.
US3748926A
Expired / Lapsed
US
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Line pressure control system for automatic power transmission
Assignee: Nissan Motor Co Ltd
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Filing: 1970-12-16
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Granted: 1973-07-31
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Expires: 1990-12-16
Abstract
Abstract A line pressure control system for an automatic power transmission capable of maintaining a line pressure at proper levels in response to the engine output torque and the torque convertor turbine speed during gear shift operation. When gear shifting is to be effected, a gear shift indicating signal is applied to a command which allows a signal corresponding to the proper line pressure to be applied to a line pressure regulating means. During a time interval starting at the occurrence of the gear shift operation, the proper line pressure depending upon the output torque and turbine speed is applied to the transmission and upon termination of the time interval a higher line pressure is applied thereto.
Inventors
- 👤 Y Mohri
- 👤 M Ishizaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:35
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/061; F16H61/0021; F16H59/00; F16H59/36; F16H59/38; F16H2059/385; F16H59/14; F16H59/18
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
297 words
A line pressure control system for controlling line pressure in an automatic transmission for a motor vehicle driven by an engine in which the automatic transmission includes a hydrodynamic torque converter having a turbine shaft, said line pressure control system comprising engine torque sensing means to sense an output torque of said engine and to generate a voltage proportional thereto; turbine speed sensing means to sense speed of said turbine shaft and to generate a voltage proportional thereto; first circuit means including clamping means connected to said turbine speed sensing means to clamp the voltage generated by said turbine speed sensing means at a given voltage level, charging means connected to said turbine speed sensing means through said clamping means to charge the voltage generated by said turbine speed sensing means, and electric means connected to said engine output torque sensing means to produce a pulse signal with a pulse width varying in dependent on the voltage generated by said engine output torque sensing means, said electric means being also connected to said charging means and periodically shutting off charging of said charging means for the duration of said pulse signal; sensing means to sense change of gear ratios and to generate a voltage signal indicative of one of said gear ratios; second circuit means including a monostable multivibrator connected to said sensing means to sense change of gear ratios, said monostable multivibrator generating a voltage signal with a constant duration upon receiving the voltage signal generated by said sensing means to sense change of gear ratios; and control means responsive to said voltage charged in said charging means of said first circuit means and to said voltage signal generated by said monostable multi-vibrator of said second circuit means to control the level of said line pressure.
Claim 2
Dependent Claim
297 words
A line pressure control system for controlling line pressure in an automatic transmission for a motor vehicle driven by an engine in which the automatic transmission includes a hydrodynamic torque converter having a turbine shaft, said line pressure control system comprising engine torque sensing means to sense an output torque of said engine and to generate a voltage proportional thereto; turbine speed sensing means to sense speed of said turbine shaft and to generate a voltage proportional thereto; first circuit means including clamping means connected to said turbine speed sensing means to clamp the voltage generated by said turbine speed sensing means at a given voltage level, charging means connected to said turbine speed sensing means through said clamping means to charge the voltage generated by said turbine speed sensing means, and electric means connected to said engine output torque sensing means to produce a pulse signal with a pulse width varying in dependent on the voltage generated by said engine output torque sensing means, said electric means being also connected to said charging means and periodically shutting off charging of said charging means for the duration of said pulse signal; sensing means to sense change of gear ratios and to generate a voltage signal indicative of one of said gear ratios; second circuit means including a monostable multivibrator connected to said sensing means to sense change of gear ratios, said monostable multivibrator generating a voltage signal with a constant duration upon receiving the voltage signal generated by said sensing means to sense change of gear ratios; and control means responsive to said voltage charged in said charging means of said first circuit means and to said voltage signal generated by said monostable multi-vibrator of said second circuit means to control the level of said line pressure.
Claim 3
Dependent Claim
25 words
A line pressure control system according to claim 1, wherein said control means includes a line pressure regulating means to regulate the line pressure level.
Claim 4
Dependent Claim
268 words
A line pressure control system according to claim 2, wherein said electric means of said first circuit means comprises an astable multivibrator, a first transistor connected at its base to the output of said engine torque sensing means and having its emitter grounded and collector connected through a resistor and a bus line to the input of said astable multivibrator, a second transistor connected at its collector through a resistor to the collector of the first transistor and at its base to the output of said astable multivibrator; a third transistor connected at its base to the collectors of said first and second transistors and at its collector to the output of said turbine speed sensing means through a resistor and having its emitter grounded, the collector of said third transistor being also connected through a smoothing circuit and a first diode to the input of said line pressure regulating means, a capacitor connected to the collectors of the first and second transistors and to the base of the third transistor, and a constant current generating circuit connected to the base of the third transistor, the arrangement being such that when the second transistor is cut off by said astable multivibrator, the capacitor is charged rendering the third transistor conductive, but the second transistor being rendered conductive, the capacitor discharges cutting off the third transistor for a preselected time period after which the constant current generating circuit renders the third transistor conducting whereby pulses appearing at the collector of the third transistor have a height proportional to engine torque and a width inversely proportional to turbine shaft speed.
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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) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |