Oil pressure control system for an automatic transmission system

Claim 2

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.

Claim 3

The oil pressure control system of claim 1, wherein said transmission gear includes a plurality of planetary gear mechanisms each comprising planetary gear component such as a sun gear, a ring gear, a plurality of planetary pinions and a carrier which carries said planetary pinions, and said friction engaging means includes a plurality of clutches and brakes, said clutch being adapted to connect selected one of said planetary gear components to an input power shift while said brake being adapted to brake a selected one of said planetary gear components against rotation.

Claim 4

The oil pressure control system of claim 2, wherein said transmission gear provides for four speed forward drive transmissions and a reverse drive transmission; said clutches include a front clutch, a rear clutch and a one-way clutch; and said brakes include a first-reverse brake, a second brake and a third brake, wherein said front clutch, said first-reverse brake and said one-way clutch are actuated for 1st speed transmission; said front clutch and said second brake are actuated for 2nd speed transmission; said first clutch and said third brake are actuated for 3rd speed transmission; said front and rear clutches are actuated for 4th speed transmission; and said rear clutch and said first-reverse brake are actuated for reverse drive transmission.

Claim 5

The oil pressure control system of claim 1, wherein said detent pressure regulating valve comprises a valve member having a first land portion which controls a release port for the 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, said detent pressure regulating valve further comprising 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.

Claim 6

The oil pressure control system of claim 4, wherein said detent pressure regulating valve generates a constant detent pressure.

Claim 7

The oil pressure control system of claim 1, wherein said speed shift valves include a 1-2 speed shift valve which comprises a valve member which is shifted between two positions and controls first and second ports, said first port transmitting an oil pressure to a first brake when opened and intercepting supply of oil pressure to said first brake when closed, said second port transmitting said line pressure to friction engaging means which accomplish 2nd speed or higher speed transmission when opened and intercepting supply of the line pressure to said friction engaging means when closed, said valve member being applied with said governor pressure which acts to urge said valve member in a first direction to close said first port and open said second port, said 1-2 speed shift valve further comprising a piston member and a compression coil spring interposed between said valve member and said piston member, said piston member being selectively applied with said detent pressure which drives said piston member in a second direction opposite to said first direction so that said valve member is applied with an increased force in said second direction by way of said compression coil spring when said detent pressure is supplied to said 1-2 speed shift valve.

Claim 8

The oil pressure control system of claim 1, wherein said speed shift valves include a 2-3 speed shift valve having a valve member which is shiftable between two shift positions and controls first and second ports, said first port transmitting the line pressure to a 2nd brake when opened and intercepting supply of the line pressure to said 2nd brake when closed, said second port transmitting the line pressure to friction engaging means which accomplish 3rd speed or higher speed transmission when opened and intercepting supply of the line pressure to said friction engaging means when closed, said valve member being applied with said governor pressure which drives said valve member in a first direction to close said first port and open said second port and said throttle pressure which drives said valve member in a second direction opposite to said first direction to open said first port and close said second port, the 2-3 speed shift valve further comprising a piston member and a compression coil spring interposed between said valve member and piston member, said piston member being selectively applied with said detent pressure which drives said piston member in said second direction thereby exerting a force to said valve member for driving same in said second direction by way of said compression coil spring.

Claim 9

The oil pressure control system of claim 1, wherein said speed shift valves include a 3-4 speed shift valve having a valve member which is shiftable between two shift positions and controls first and second ports, said first port transmitting said line pressure to a 3rd brake when opened and intercepting supply of said line pressure to said 3rd brake when closed, said second port transmitting said line pressure to a rear clutch when opened and intercepting supply of said line pressure to said rear clutch when closed, said valve member being applied with said governor pressure which drives said valve member in a first direction to close said first port and open said second port and said throttle pressure which drives said valve member in a second direction opposite to said first direction, said 3-4 speed shift valve further comprising a piston member and a compression coil spring interposed between said valve member and piston member, said piston member being selectively applied with said detent pressure which drives said piston member in said second direction thereby exerting an increased force to said valve member by way of said compression coil spring, said force driving said valve member in said second direction.

Claim 10

The oil pressure control system of claim 1, wherein said line pressure regulating valve provides for three substantially different line pressure levels according to the shifting conditions of said plurality of speed shift valves and said manual shift valve, said line pressure being at a highest level when said manual shift valve is shifted to R range, a medium level when said manual shift valve is shifted to P, N or D, 3, 2 or 1 range and said speed shift valves are shifted to establish 1st speed transmission, and a lowest level in the other shifting conditions.

Claim 11

The oil pressure control system of claim 9, wherein said line pressure regulating valve comprises a valve member which controls a release port for the line pressure, said valve member being basically positioned by a balance between the line pressure which drives said valve member in a first direction to open said release port and a spring force which drives said valve member in a second direction opposite to said first direction, said valve member being further selectively applied with the line pressure in said first direction through a first port, the throttle pressure in said second direction through a second port and a pressure modulated from the line pressure in said second direction through a third port according to the shifting conditions of said plurality of speed shift valves and said manual shift valve.

Claim 12

The oil pressure control system of claim 10, wherein said first port is connected to a first port in said manual shift valve, said latter mentioned first port being controlled by the valve member of said manual shift valve to be supplied with the line pressure when the manual shift valve is shifted to N, D, 3, 2 or 1 range, said second port of said line pressure regulating valve being connected to a main port of said throttle pressure regulating valve, said main port generating said throttle pressure, said third port of said line pressure regulating valve being connected to a second port of said manual shift valve by way of a pressure regulating valve and 1-2 speed shift valve, said second port of said manual shift valve being controlled by said valve member of the manual shift valve to be supplied with the line pressure when the manual shift valve is shifted to R, N, 3, 2 or 1 range, said 1-2 speed shift valve communicating the line pressure to said third port of said line pressure regulating valve when it is shifted to a position to accomplish 1st speed transmission.

Claim 13

The oil pressure control system of claim 1, wherein said throttle pressure regulating valve comprises a valve member which controls a release port for the line pressure, said release port generating said throttle pressure, said valve member being basically positioned by a balance between the throttle pressure which acts to urge said valve member in a first direction to close said release port and a spring force which drives said valve member in a second direction opposite to said first direction, said spring force being adapted to be increased according to increase of throttle valve opening.

Claim 14

The oil pressure control system of claim 12, wherein said spring force is applied by a compression spring which is supported by a second valve member at one end thereof, said second valve member being displaced by a throttle valve operating mechanism to compress said spring according to increase of throttle valve opening.

Claim 15

The oil pressure control system of claim 13, wherein said second valve member controls a kick down port which is opened to be supplied with said detent pressure when said second valve member is displaced beyond a predetermined stroke by said throttle valve operating mechanism, said stroke corresponding to full actuation of accelerating pedal, said detent pressure supplied to said kick down port being transmitted to said speed shift valves for shifting said speed shift valves to their lower speed shift positions.

Claim 16

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.

Claim 17

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.