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US3747439A Expired / Lapsed US ⏱️ 0.0 years remaining

Hydraulic control system for automatic transmissions

Assignee: Toyota Motor Corp
•
Filing: 1971-05-05
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Granted: 1973-07-24
•
Expires: 1991-05-05
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Abstract

Abstract A hydraulic control system for automatic transmissions having hydraulic servos for actuating friction engagement means comprises an oil pump for producing an oil pressure to be supplied to the servos, a pressure regulator valve for producing a desired line pressure in dependence on the speed and the output of an engine, a throttle valve for producing a throttle pressure corresponding to the throttle valve opening of the engine, a governor valve for producing a governor pressure corresponding to the engine speed, a manual valve for selectively distributing the line pressure to the servos, a 1-2 shift valve for accomplishing shift between a first and a second speed condition in dependence on the running condition of the vehicle controlled by the throttle pressure and the governor pressure, a 2-3 shift valve for accomplishing shift between the second and a third speed condition, an accumulator unit for slowing down supply of the line pressure to the servo for the third speed, a 2-3 timing valve for providing the timing of the up-shift or the down-shift between the second and third speed condition and an orifice control valve for controlling supply of the line pressure to the servo for the second speed. The supply of the line pressure to the servo for the third speed upon upshift from the second speed condition to the third speed condition is slowed down by the accumulator unit and the time for exhausting the servo for the second speed is determined by the 2-3 timing valve whereby an overlap of engagement and disengagement of the friction engagement means is provided. The overlap may be varied in dependence on the throttle pressure. Upon downshift from the third speed condition to the second speed condition, the servo for the third speed is relieved of pressure, and the 2-3 timing valve determines the time for supplying the line pressure to the servo for the second speed in dependence on the throttle pressure. Further the orifice control valve controls flow of the line pressure so that a desired overlap may be provided as in the case of upshift.

Inventors

  • 👤 S Uozumi
  • 👤 I Sakai

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 14:20
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/08

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 243 words
In an automatic transmission for an engine driven vehicle including an engine, speed change gearing having at least two frictional engagement means and a first and a second associated hydraulic servo means for respectively actuating said engagement means, pressure supply means, and means for transmitting pressure from said supply means to said first and second servo means, with pressure supply of said first servo means and pressure relief of said second servo means providing a first speed condition, and with pressure relief of said first servo means and pressure supply of said second servo means providing a second speed condition, the combination comprising: shift valve means controlled in response to both the output of said engine and the speed of said vehicle to pressurize or relieve said first servo means; and timing valve means responsive to pressure supply in said first servo means for relieving said second servo means when the supply pressure to said first servo means exceeds a predetermined value with respect to the output of said engine and for pressurizing said second servo means when said supply pressure to said first servo means decreases below said predetermined value; said timing valve means being responsive to the output level of said engine to control the timing of pressure supply and relief to said second servo means in dependence thereupon thereby to provide overlap in the shifting operation of said first and second servo means between said first and second speed conditions.
Claim 2
Dependent Claim 243 words
In an automatic transmission for an engine driven vehicle including an engine, speed change gearing having at least two frictional engagement means and a first and a second associated hydraulic servo means for respectively actuating said engagement means, pressure supply means, and means for transmitting pressure from said supply means to said first and second servo means, with pressure supply of said first servo means and pressure relief of said second servo means providing a first speed condition, and with pressure relief of said first servo means and pressure supply of said second servo means providing a second speed condition, the combination comprising: shift valve means controlled in response to both the output of said engine and the speed of said vehicle to pressurize or relieve said first servo means; and timing valve means responsive to pressure supply in said first servo means for relieving said second servo means when the supply pressure to said first servo means exceeds a predetermined value with respect to the output of said engine and for pressurizing said second servo means when said supply pressure to said first servo means decreases below said predetermined value; said timing valve means being responsive to the output level of said engine to control the timing of pressure supply and relief to said second servo means in dependence thereupon thereby to provide overlap in the shifting operation of said first and second servo means between said first and second speed conditions.
Claim 3
Dependent Claim 35 words
An automatic transmission as claimed in claim 1, comprising a passage means for establishing direct communication between the pressure supply to said first servo means and said second valve chamber of said timing valve means.
Claim 4
Dependent Claim 145 words
An automatic transmission according to claim 1, wherein said timing valve means comprises a first pressure chamber, a second pressure chamber, a third pressure chamber and control means movable in response to the pressure in said first, second and third chambers to control pressure supply to said second servo means, said first and said second chambers having applied thereto the supply pressure to said first servo means and being arranged to have the respective pressures therein act upon said control means in opposing relationship with said second chamber having a pressure area acting upon said control means which is smaller than that of said first chamber, said third valve chamber having applied thereto a pressure which is representative of said engine output and being arranged to have the pressure therein act upon said control means in opposed relationship to the pressure in said first chamber.
Claim 5
Dependent Claim 22 words
An automatic transmission according to claim 3 wherein the degree of said overlap is determined by the output level of said engine.
Claim 6
Dependent Claim 64 words
An automatic transmission according to claim 3, comprising accumulator means for establishing pressure communication between said first servo means and said second chamber of said timing valve means, said accumulator means operating to apply the supply pressure existing in said first servo means to said second valve chamber of said timing valve means when said first servo means supply pressure reaches a predetermined level.
Claim 7
Dependent Claim 61 words
An automatic transmission according to claim 5, wherein said accumulator means comprises piston means having said first servo means supply pressure applied thereto, and spring means acting upon said piston means in opposing relationship to said supply pressure whereby said supply pressure is applied to said second chamber of said timing value means upon a predetemined displacement of said piston means.

References Cited (Backward Citations)

US3014383A Cited
US3438285A Cited
US3509784A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-07-23 1977-01-22 1977-07-24 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-07-23 1981-01-22 1981-07-24 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-07-23 1985-01-22 1985-07-24 $7700.00 Window Closed / Lapsed

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