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US3709067A Expired / Lapsed US ⏱️ 0.0 years remaining

Hydraulic control system for transmissions

Assignee: Toyota Motor Corp
•
Filing: 1971-02-10
•
Granted: 1973-01-09
•
Expires: 1991-02-10
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Abstract

Abstract The hydraulic control system is applied to transmissions in which the high speed range is obtained by supplying oil to a first one of at least two hydraulic servos and discharging oil from a second hydraulic servo. The low speed range is obtained by discharging oil from the first hydraulic servo and supplying oil to the second hydraulic servo. This hydraulic control system comprises a hydraulic pressure source, a pressure regulator valve, a governor valve, a throttle valve and first and second shift valves. The hydraulic control pressure supplied from the hydraulic pressure source and regulated by the pressure regulator valve is directed through the first shift valve to the first hydraulic servo and is also directed through the second shift valve to the second hydraulic servo. The governor pressure developed by the governor valve, which conforms to the vehicle velocity, and the throttle pressure developed by the throttle valve, which conforms to the engine output, are applied to the first shift valve. The throttle pressure, moreover, actuates the second shift valve. In addition, the hydraulic pressure of the first hydraulic servo is applied to the second shift valve to oppose the throttle pressure. Thus, the oil discharge starting time of the second hydraulic servo at the time of upshift is delayed in accordance with the hydraulic pressure that is supplied to the first hydraulic servo. The degree of the time delay also is changed in accordance with the magnitude of the throttle pressure. The second shift valve forms a variable capacity accumulator chamber at the point at which the hydraulic pressure is applied from the first hydraulic servo. An orifice for reducing the rate of hydraulic pressure increase at the time oil is supplied to the first hydraulic servo as well as a check valve for enhancing the rate of hydraulic pressure decrease at the time oil is discharged from the first hydraulic servo are provided in an oil passage between the accumulator chamber and the first shift valve. By virtue of the orifice and the check valve, the gradient of the pressure change due to the oil supplied to the first hydraulic servo at the time of upshift is reduced. The degree of this gradient reduction changes to conform to the magnitude of the throttle pressure. Furthermore, at the time of downshift, the second shift valve is operated in response to the oil discharge from the first hydraulic servo so supply oil to the second hydraulic servo, and therefore the downshift oil supply starting time is reduced in accordance with the oil discharged from the first hydraulic servo as well as the magnitude of the throttle pressure.

Inventors

  • 👤 S Ito

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-27 05:23
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/04; F16H61/06; F16H61/065; F16H61/08; F16H61/68; F16H61/684; Y; Y10; Y10T; Y10T74/00; Y10T74/19; Y10T74/19219; Y10T74/19293; Y10T74/19298; Y10T74/19326; Y10T74/19377; Y10T74/19414; Y10T74/19419; Y10T74/19423; Y10T74/19428; Y10T74/19433

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 278 words
In a transmission, for an automotive vehicle engine, including a variable ratio speed change gear, at least two friction engaging members and respective hydraulic servos for operating the members, and in which a first speed range is obtained by supplying oil under pressure to a first hydraulic servo and discharging oil from a second hydraulic servo, and a second speed range is obtained by supplying oil under pressure to the second hydraulic servo and discharging oil from the first hydraulic servo: a hydraulic control system comprising, in combination, a source of oil at a control pressure; first flow control means connected to said source; first passage means connecting said first control means to said first hydraulic servo; means subjecting said first control means to a first operating force in accordance with the engine output and to an opposing second operating force in accordance with the vehicle velocity, said first control means connecting said first passage means to said source or to discharge in accordance with the relative magnitudes of said first and second operating forces; a second flow control means connected to said source; second passage means connecting said second flow control means to said second hydraulic servo; and further passage means connecting said second flow cOntrol means to said first hydraulic servo and subjecting said second flow control means to the hydraulic pressure effective on said first hydraulic servo; said second flow control means connecting said second passage means to discharge when the hydraulic pressure in said first hydraulic servo exceeds a set value, and connecting said second passage means to said source when the hydraulic pressure in said first hydraulic servo decreases below said set value.
Claim 2
Dependent Claim 278 words
In a transmission, for an automotive vehicle engine, including a variable ratio speed change gear, at least two friction engaging members and respective hydraulic servos for operating the members, and in which a first speed range is obtained by supplying oil under pressure to a first hydraulic servo and discharging oil from a second hydraulic servo, and a second speed range is obtained by supplying oil under pressure to the second hydraulic servo and discharging oil from the first hydraulic servo: a hydraulic control system comprising, in combination, a source of oil at a control pressure; first flow control means connected to said source; first passage means connecting said first control means to said first hydraulic servo; means subjecting said first control means to a first operating force in accordance with the engine output and to an opposing second operating force in accordance with the vehicle velocity, said first control means connecting said first passage means to said source or to discharge in accordance with the relative magnitudes of said first and second operating forces; a second flow control means connected to said source; second passage means connecting said second flow control means to said second hydraulic servo; and further passage means connecting said second flow cOntrol means to said first hydraulic servo and subjecting said second flow control means to the hydraulic pressure effective on said first hydraulic servo; said second flow control means connecting said second passage means to discharge when the hydraulic pressure in said first hydraulic servo exceeds a set value, and connecting said second passage means to said source when the hydraulic pressure in said first hydraulic servo decreases below said set value.
Claim 3
Dependent Claim 43 words
A hydraulic control system, as claimed in claim 1, including means subjecting said second shift valve to said first operating force in opposition to the hydraulic pressure effective on said first hydraulic servo; said set value being controlled by said first operating force.
Claim 4
Dependent Claim 30 words
A hydraulic control system, as claimed in claim 1, including an accumulator in communication with said first hydraulic servo and accumulating the hydraulic pressure effective on said first hydraulic servo.
Claim 5
Dependent Claim 19 words
A hydraulic control system, as claimed in claim 3, in which said second flow control means includes said accumulator.
Claim 6
Dependent Claim 54 words
A hydraulic control system, as claimed in claim 1, including an orifice in said first passage means restricting flow of oil to said first shift valve; and a check valve connected to said first passage means in by-passing relation with said orifice and providing for unrestricted discharge of oil from said first hydraulic servo.
Claim 7
Dependent Claim 164 words
A hydraulic control system, as claimed in claim 1, including a pressure regulator constituting said source of oil at a control pressure; said first and second flow control means comprising first and second shift valves, respectively; said means subjecting said first shift valve to a first operating force in accordance with the engine output comprising a throttle responsive valve connected to said pressure regulator and a conduit connecting said throttle responsive valve to said first shift valve; said means subjecting said first shift valve to an opposing second operating force in accordance with the vehicle velocity comprising a governor valve connected to said pressure regulator and a conduit connecting said governor valve to said first shift valve; said means subjecting said second shift valve to said first operating force comprising a conduit connecting said second shift valve to said throttle responsive valve and applying the throttle pressure to said second shift valve in opposition to the hydraulic pressure effective on said first hydraulic servo.
Claim 8
Dependent Claim 43 words
A hydraulic control system, as claimed in claim 6, in which said second shift valve includes a hydraulic accumulator in communication with said first hydraulic servo and operable to effect a gradual increase in the hydraulic pressure effective on said first hydraulic servo.
Claim 9
Dependent Claim 81 words
A hydraulic control system, as claimed in claim 7, including an orifice in said first passage means restricting flow of oil to said first hydraulic servo and to said accumulator to retard the rate of pressure increase; and a check valve connected to said first passage means in by-passing relation with said orifice and providing for unrestricted discharge of oil from said first hydraulic servo to accelerate the rate of pressure decrease in said first hydraulic servo and in said accumulator.
Claim 10
Dependent Claim 84 words
A hydraulic control system, as claimed in claim 1, in which said first and second flow control means comprise first and second shift valves, respectively; said means subjecting said first shift valve to a first operating force in accordance with the engine output and to an opposing second operating force in accordance with the vehicle velocity comprising electromagnetic means operatively associated with said first shift valve; and means applying, to said electromagnetic means, electrical signals corresponding to the engine output and the vehicle velocity.

References Cited (Backward Citations)

US3225619A Cited
US3258984A Cited
US3587354A Cited
US3572179A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-01-09 1976-07-10 1977-01-09 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-01-09 1980-07-10 1981-01-09 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-01-09 1984-07-10 1985-01-09 $7700.00 Window Closed / Lapsed

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