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 said governor pressure and said throttle pressure so as to change over the supply of oil pressure to said friction engaging means for shifting transmission between lower and higher speed stages; a manual shift valve which is shifted by hand among a plurality of ranges for effecting a selected transmission; and a speed shift timing valve which is related to upper and lower speed shift valves and is shifted for variably restricting supply and exhaust of oil to and from upper and lower speed stage friction engaging means which are alternately actuated according to the shifting of said speed shift valves in the manner such that in the upshifting process the rate of supplying oil to said upper shift stage friction engaging means is gradually decelerated while the rate of exhausting oil from said lower speed stage friction engaging means is gradually accelerated, said speed shift timing valve comprising a valve element, first and second port means adapted to be controlled by said valve element, said first port means providing a middle portion of a passage means for supplying oil to said upper speed stage friction engaging means while said second port means providing a middle portion of a passage means for supplying oil to said lower speed stage friction engaging means, and a third port means connected with said passage means for supplying oil to said upper speed stage friction engaging means, wherein the pressure applied to said third port drives said valve element towards a shift position where said valve element applies more restriction to said first port means and applies less restriction to said second port means.

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 components 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 shaft 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 and 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 front 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 speed shift valves include a 2-3 speed shift valve which comprises a valve member, said valve member being shifted between first and second shift positions to control first, second and third ports, said first port connecting to a second brake and being supplied with the line pressure when said valve member is shifted to said first shift position while said first port being isolated from supply of the line pressure and connected to said third port when said valve member is shifted to said second shift position, said second port connecting to a third brake through a passage including said speed shift timing valve and being supplied with the line pressure when said valve member is shifted to said second shift position while said second port being isolated from supply of the line pressure when said valve member is shifted to said first shift position, said speed shift timing valve comprising a valve member which is shifted between first and second shift positions to control first and second ports, said valve member being adapted to be supplied with oil pressure existing in said third brake at its one end, said oil pressure acting to urging said valve member toward said second shift position while said valve member being applied with the throttle pressure and a spring force at the other end thereof, said throttle pressure and spring force driving said valve member toward said first shift position, said passsage comprising first and second parallel passage portions, said first passsage portion including first and second parallel sub-passage portions, said first sub-passage portion being constantly opened while said second sub-passage portion being opened through said first port of said speed shift timing valve when said valve member of said speed shift timing valve is shifted to said first shift position while being closed when said valve member is shifted to said second shift position, said second passage portion including a check valve which prevents flow therethrough toward said third brake while allowing for flow therethrough in the opposite direction, said third port of said 2-3 speed shift valve being connected to a drain passage which includes first and second parallel passage portions, said first passage portion being constantly opened, said second passage portion being opened through said second port of said speed shift timing valve when said valve member of said speed shift timing valve is shifted to said second shift position while said second passage portion being intercepted when said valve member is shifted to said first shift position.

Claim 6

The oil pressure control system of claim 1, wherein said speed shift valves include a 3-4 speed shift valve which comprises a valve member, said valve member being shifted between first and second shift positions to control first, second and third ports, said first port connecting to a rear clutch through a passage including said speed shift timing valve and being supplied with the line pressure when said valve mamber is shifted to said second shift position while being intercepted from supply of the line pressure when said valve member is shifted to said first shift position, said second port connecting to a third brake and being supplied with the line pressure when said valve member is shifted to said first shift position while being intercepted from supply of the line pressure and connected to said third port when said valve member is shifted to said second shift position, said speed shift timing valve comprising a valve member which is shifted between first and second shift positions and controls first and second ports, said valve member being applied with oil pressure existing in said rear clutch at one end thereof, said oil pressure driving said valve member toward said second shift position while said valve member being applied with the throttle pressure and a spring force at the other end thereof, said throttle pressure and spring force driving said valve member toward said first shift position, said passage comprising first and second parallel passage portions, said first passage portion including first and second parallel sub-passage portions, said first sub-passage portion being constantly opened, said second sub-passage portion being opened through said first port of said speed shift timing valve when said valve member of said speed shift timing valve is shifted to said first position while being intercepted when said valve member is shifted to said second shift position, said second passage portion including a check valve which prevents flow therethrough toward said rear clutch while allowing for flow therethrough in the opposite direction, said third port of said 3-4 speed shift valve being connected to a drain passage which includes first and second parallel passage portions, said first passage portion being constantly opened, said second passage portion being intercepted when said valve member of said speed shift timing valve is shifted to said first shift position while it is opened through said second port of said speed shift timing valve when said valve member is shifted to said second shift position.

Claim 9

The oil pressure control system of claim 1, wherein said speed shift valves include a 2-3 speed shift valve (2-3 SV) and a 3-4 speed shift valve (3-4 SV), said speed shift timing valve related to 2-3 SV is a 2-3 speed shift timing valve (2-3 STV) while said speed shift timing valve related to said 3-4 SV being a 3-4 speed shift timing valve (3-4 STV), said 2-3 SV comprising a valve member which is shifted between first and second shift positions to control first, second and third ports, said first port connecting to a third brake through a first passage including said 3-4 SV and said 2-3 STV and being supplied with the line pressure when said valve member is shifted to said second shift position while being intercepted from supply of the line pressure when said valve member is shifted to said first shift position, said second port connecting to a second brake and being supplied with the line pressure when said valve member is shifted to said first shift position while being intercepted from supply of the line pressure and connected to said third port when said valve member is shifted to said first shift position; said 2-3 STV comprising a valve member which is shifted between first and second shift positions and controls first and second ports, said 2-3 STV further comprising a piston member which abuts against a first end of said valve member, said valve member being applied with oil pressure existing in said third brake at said first end, said oil pressure driving said valve member toward said second shift position, said valve member further being applied with the throttle pressure and a spring force at an opposite end thereof, said throttle pressure and spring force driving said valve member toward said first shift position; said 3-4 SV comprising a valve member which is shifted between first and second shift positions and controls first, second, third and fourth ports, said second port connecting to said first port of said 2-3 SV, said first port of 3-4 SV connecting to a rear clutch through a third passage including said 3-4 STV and being connected to said second port of 3-4 SV to be supplied with the line pressure when the valve member of 3-4 SV is shifted to said second shift position while intercepted from supply of the line pressure when said valve member is shifted to said first shift position, said second and third ports of 3-4 SV being connected to complete said second passage when the valve member of 3-4 SV is shifted to said first shift position while intercepting said second passage when said valve member is shifted to said second shift position, said second passage including first and second parallel passage portions, said first passage portion further including first and second parallel sub-passage portions, said first sub-passage portion being constantly opened, said second sub-passage portion being opened through said first port of 2-3 STV when said valve member of 2-3 STV is shifted to said first shift position while being intercepted when said valve member is shifted to said second shift position, said second passage portion including a check valve which prevents flow therethrough toward said third brake while allowing for flow therethrough in the opposite direction, said third port of 2-3 SV being connected to a drain passage which includes first and second parallel passage portions, said first passage portion being constantly opened, said second passage portion being opened through said second port of 2-3 STV when said valve member of 2-3 STV is shifted to said second shift position while being intercepted when said valve member is shifted to said first shift position; said 3-4 STV comprising a valve member which is shifted between first and second shift positions and controls first and second ports, said valve member being applied with oil pressure existing in said rear clutch at one end thereof, said oil pressure driving said valve member toward said second shift position, said valve member further being applied with the throttle pressure and a spring force at an opposite end thereof, said throttle pressure and spring force acting to urge said valve member toward said first shift position, said third passage including first and second parallel passage portions, said first passage portion including first and second parallel sub-passage portions, said first sub-passage portion being constantly opened, said second sub-passage portion being opened through said first port of 3-4 STV when said valve member of 3-4 STV is shifted to said first shift position while being intercepted when said valve member is shifted to said second shift position, said second passage portion including a check valve which prevents flow therethrough toward said rear clutch while allowing for flow therethrough in the opposite direction, said fourth port of 3-4 SV being connected to a drain passage which includes first and second parallel passage portions, said first passage portion being constantly opened, said second passage portion being opened through said second port of 3-4 STV when said valve member of 3-4 STV is shifted to said second shift position while being intercepted when said valve member is shifted to said first shift position, said piston member of 2-3 STV being applied with said pressure existing in said rear clutch through a portion of said third passage, said pressure driving said piston member in the direction to drive said valve of 2-3 STV to said second shift position.

Claim 10

The oil pressure control system of claim 1, wherein a passage which transmits oil pressure to said friction engaging means is provided with a buffering accumulator, said accumulator comprising a fluid displacing element which is supported by a spring means.

Claim 11

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 12

The oil pressure control system of claim 8, 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 13

The oil pressure control system of claim 9, 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, D, 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 14

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 drives 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 15

The oil pressure control system of claim 11, 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 16

The oil pressure control system of claim 1, wherein said passage means for supplying oil to said upper speed stage friction engaging means includes a bypass passage means including a check valve and bypassing said first port means, said check valve being adapted to permit oil flow only in the direction of exhausting said upper speed stage friction engaging means.