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US3707890A Expired / Lapsed US ⏱️ 0.0 years remaining

Hydraulic control system for transmissions

Assignee: Toyota Motor Corp
•
Filing: 1971-02-10
•
Granted: 1973-01-02
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Expires: 1991-02-10
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Abstract

Abstract A hydraulic control system, for transmissions in which the high speed range is obtained by supplying oil under pressure into a first hydraulic servo while discharging the oil from a second hydraulic servo, and the low speed range is obtained by supplying oil under pressure to the second hydraulic servo while discharging oil from the first hydraulic servo, includes a source of hydraulic fluid under pressure, a pressure regulator valve, a governor valve, a throttle valve, a shift valve an orifice, an orifice control valve and an accumulator. The shift valve is connected to the source of regulated pressure and to exhaust, and directly controls supply and exhaust fluid relative to the first servo. The shift valve is connected through a passage having a flow restricting orifice therein to the second servo, and is also connected to the orifice control valve, which latter is in communication with the second servo. The orifice control valve has a first position blocking direct communication between the shift valve and the second servo and a second position by-passing the flow restricting orifice and establishing direct communication between the shift valve and the second servo. The orifice control valve is subjected to the throttle pressure and the pressure in the first hydraulic servo, acting in opposition. When shifting from low speed to high speed, the orifice control valve has its second position so that the pressure in the second servo is slowly decreased while the pressure in the first servo is rapidly increased. The increased pressure in the first servo moves the orifice control valve to its second position so that pressure is rapidly exhausted from the second servo after the pressure in the first servo has attained a predetermined value. In shifting from high speed to low speed, oil is rapidly discharged from the first servo to rapidly decrease the pressure therein, with the orifice control valve initially occupying its second position so that the pressure in the second servo is rapidly increased. As the pressure in the first servo decreases, the orifice control valve is moved, by the throttle pressure, back to its first position to decrease the rate of increase of the pressure in the second servo.

Inventors

  • 👤 S Ito

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-02 10:31
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/08; F16H61/68; F16H61/684

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 303 words
In a transmission including a variable ratio speed change gear, at least two friction engaging members, respective hydraulic servos for operating the members, and a source of hydraulic fluid under pressure, with high speed range being obtained by supplying hydraulic fluid under pressure to a first hydraulic servo and exhausting hydraulic fluid from a second hydraulic servo, and low speed range being obtained by exhausting hydraulic fluid from the first hydraulic servo and supplying hydraulic fluid under pressure to the second hydraulic servo: a hydraulic control system for said transmission comprising, in combination, a shift valve connected between said source and said first and second hydraulic servos, and having a first position, connecting said first hydraulic servo to said source and said second hydraulic servo to exhaust, and a second position, connecting said first hydraulic servo to exhaust and said second hydraulic servo to said source; a first passage connecting said shift valve to said first hydraulic servo; a restricted flow second passage connecting said shift valve to said second hydraulic servo; said first and second passages serving for supply and exhaust of hydraulic fluid relative to the associated hydraulic servos; and an orifice control valve connected between said shift and said second hydraulic servo and having a first position connecting said shift valve directly to said second hydraulic servo in by-passing relation to said second passage and a second position in which said shift valve is connected to said second hydraulic servo only through said restricted flow second passage; and means operable to move said orifice control valve to its second position when the hydraulic pressure existing in said first hydraulic servo is lower than a said value, and to move said orifice control valve to its first position when the hydraulic pressure in said first hydraulic servo exceeds said set value.
Claim 2
Dependent Claim 303 words
In a transmission including a variable ratio speed change gear, at least two friction engaging members, respective hydraulic servos for operating the members, and a source of hydraulic fluid under pressure, with high speed range being obtained by supplying hydraulic fluid under pressure to a first hydraulic servo and exhausting hydraulic fluid from a second hydraulic servo, and low speed range being obtained by exhausting hydraulic fluid from the first hydraulic servo and supplying hydraulic fluid under pressure to the second hydraulic servo: a hydraulic control system for said transmission comprising, in combination, a shift valve connected between said source and said first and second hydraulic servos, and having a first position, connecting said first hydraulic servo to said source and said second hydraulic servo to exhaust, and a second position, connecting said first hydraulic servo to exhaust and said second hydraulic servo to said source; a first passage connecting said shift valve to said first hydraulic servo; a restricted flow second passage connecting said shift valve to said second hydraulic servo; said first and second passages serving for supply and exhaust of hydraulic fluid relative to the associated hydraulic servos; and an orifice control valve connected between said shift and said second hydraulic servo and having a first position connecting said shift valve directly to said second hydraulic servo in by-passing relation to said second passage and a second position in which said shift valve is connected to said second hydraulic servo only through said restricted flow second passage; and means operable to move said orifice control valve to its second position when the hydraulic pressure existing in said first hydraulic servo is lower than a said value, and to move said orifice control valve to its first position when the hydraulic pressure in said first hydraulic servo exceeds said set value.
Claim 3
Dependent Claim 34 words
The hydraulic control system for transmissions as defined in claim 1, wherein an accumulator for accumulating the hydraulic pressure existing in said second hydraulic servo is connected in series with said second hydraulic servo.
Claim 4
Dependent Claim 53 words
The hydraulic control system for transmissions as defined in claim 1, including an accumulator, for accumulating the hydraulic pressure existing in said second hydraulic servo, connected in series with said second hydraulic servo; and means operable responsive to the output of an engine connecTed to said transmission providing a signal controlling said accumulator.
Claim 5
Dependent Claim 52 words
The hydraulic control system for transmissions as defined in claim 1, including means applying the hydraulic pressure existing in said first hydraulic servo to said orifice control valve, and means operable responsive to the output of an engine connected to said transmission and providing a control signal to said orifice control valve.
Claim 6
Dependent Claim 35 words
The hydraulic control system for transmissions as defined in claim 1, including an orifice in said second passage providing a flow restriction therein; said orifice control valve being connected in by-passing relation with said orifice.
Claim 7
Dependent Claim 55 words
The hydraulic control system for transmissions as defined in claim 1, including solenoid means operable to effect control movements of said shift valve; and means energizing said solenoid with a voltage proportional to the velocity of a vehicle having said transmission and a voltage proportional to the output of an engine connected to said transmission.

References Cited (Backward Citations)

US3572177A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-01-02 1976-07-03 1977-01-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-01-02 1980-07-03 1981-01-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-01-02 1984-07-03 1985-01-02 $7700.00 Window Closed / Lapsed

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