Oil pressure control system for an automatic transmission system
AssigneeToyota Jidosha Kogyo Kabushiki Kaisha
InventorYutaka Taga
Life of this patent
Estimating the term…
Abstract
An oil pressure control system for an automatic transmission system which includes a fluid torque converter, a transmission gear and friction engaging means adapted to be selectively supplied with line pressure for establishing a selected transmission engagement in said transmission gear, wherein speed shift valves which change over the supply of said line pressure to said friction engaging means are selectively supplied with a detent pressure generated by properly reducing said line pressure. The detent pressure acts to forcibly shift said speed shift valves toward a shift position for establishing a lower speed range in a manner that a speed shift point is biased to a higher speed range by an amount determined by the level of said detent pressure.
Claims15
An oil pressure control system for an automatic transmission system which includes a fluid torque converter, a transmission gear and friction engaging means for establishing a selected transmission engagement in said transmission gear, comprising:
- a source of oil pressure;
- a line pressure regulating valve which generates a line pressure from the oil pressure of said source, said line pressure being regulated to be suitable for operating said friction engaging means;
- a throttle pressure regulating valve which generates a throttle pressure from said line pressure, said throttle pressure increasing as the engine torque increases;
- a governor pressure regulating valve which generates a governor pressure from said line pressure, said governor pressure increasing as the vehicle speed increases;
- a plurality of speed shift valves which are shifted according to a balance of said governor pressure and said throttle pressure so as to change over the supply of oil pressure to said friction engaging means for shifting the transmission between lower and higher speed stages, at least one of said speed shift valves having a detent port adapted to be supplied with a detent pressure which counteracts said governor pressure to bias a balancing point of said governor pressure and said throttle pressure toward a higher speed range;
- a manual shift valve which is shifted by hand among forward, reverse, neutral and low speed ranges for effecting a selected transmission, said manual shift valve having a low speed port or ports adapted to be opened when it has been shifted to a low speed range so as to provide said detent pressure to said detent port or ports of said speed shift valve or valves;
- and
- a detent pressure regulating valve which generates a specific reduced pressure from said line pressure, said reduced pressure serving as said detent pressure supplied to said detent port or ports of said speed shift valve or valves.
An oil pressure control system for an automatic transmission system which includes a fluid torque converter, a transmission gear and friction engaging means for establishing a selected transmission engagement in said transmission gear, comprising:
- a source of oil pressure;
- a line pressure regulating valve which generates a primary line pressure from the oil pressure of said source, said primary line pressure being regulated to be suitable for operating said friction engaging means;
- a throttle pressure regulating valve which generates a throttle pressure from said primary line pressure, said throttle pressure increasing as the engine torque increases;
- a governor pressure regulating valve which generates a governor pressure from said primary line pressure, said governor pressure increasing as the vehicle speed increases;
- a plurality of speed shift valves which are shifted according to a balance of said governor pressure and said throttle pressure so as to change over the supply of oil pressure to said friction engaging means for shifting the transmission between lower and higher speed stages, at least one of said speed shift valves having a detent port adapted to be supplied with a detent pressure which counteracts said governor pressure to bias a balancing point of said governor pressure and said throttle pressure toward a higher speed range;
- a manual shift valve which is shifted by hand among forward, reverse, neutral and low speed ranges for effecting a selected transmission said manual shift valve having a low speed port or ports adapted to be opened when it has been shifted to a low speed range so as to provide said detent pressure to said detent port or ports of said speed shift valve or valves;
- a detent pressure regulating valve which generates a specific reduced pressure from said primary line pressure, said reduced pressure serving as said detent pressure being supplied to said detent port or ports of said speed shift valve or valves;
- said detent pressure regulating valve including a valve member having a first land portion which controls a release port for the primary line pressure in a manner to restrict said release port when said valve member moves in a first direction, said release port generating said detent pressure;
- said valve member having a second land portion which prevents a face to be applied with said detent pressure generated in said release port in said first direction to restrict said release port;
- and
- said detent pressure regulating valve further includes a compression spring which resiliently urges said valve member in a second direction opposite to said first direction against the force which said detent pressure applies to said face of said second land portion.
Dependencies are inferred from the claim text.