Gm Global Technolgoy Operations, Inc.

Jeffrey J Cole

Charles Francis Long

Phillip F McCauley

Martin Robert Dadel

Phillip F Mc Cauley

A control system is provided for selectively actuating a dual area apply piston having first and second piston areas each selectively biased by hydraulic pressure within a respective first and second fill cavities. The control system includes a pressure regulator valve, a dual area activation valve, and a solenoid valve operable to selectively and variable operate the pressure regulator valve to effect biasing of the first and second piston areas by communicating hydraulic pressure to the first fill cavity and/or the second fill cavity.

Control system for a transmission with a dual area apply piston for a torque-transmitting mechanism engagement

A pressure regulator valve is provided having a valve spool slidably disposed within a stepped bore defined by a valve body. A first pressure responsive surface area is defined on the valve spool and is subject to pressurized fluid from a main pressure source. A second pressure responsive surface area is defined on the valve spool and is subject to pressurized fluid from a control source. Additionally, a third pressure responsive surface area is defined on the valve spool and is selectively subject to pressurized fluid from one of the main pressure source and the control source. A sleeve is slidably disposed within the stepped bore, the sleeve being operable to selectively distribute pressurized fluid from one of the main pressure source and the control source to the third pressure responsive surface area to effect a change in pressure gain of the pressure regulator valve.

Pressure regulator valve with boost feature

Provided is an apparatus to enable a torque transmitting mechanism within an automatically shiftable power transmission to disengage at vehicle stop such that the slip within a fluid drive device is reduced. When vehicle movement is required a main pressure regulator trims the torque transmitting mechanism into engagement. A method of reducing engine load at vehicle stop by employing the apparatus of the present invention is also provided.

Reduced engine load at stop apparatus and method

A power transmission has axially aligned torque transmitting mechanisms. Each torque transmitting mechanism has a backing plate slidably disposed on a spline formed in the housing of the power transmission. Each backing plate has a locating ring to limit the axial movement of the backing plate and therefore the members of the torque transmitting mechanism during engagement. The locating rings are disposed in an L-shaped groove such that the outer locating ring is narrower that the inner locating ring. The backing plate of one of the torque transmitting mechanisms has an outer segmented annular extension that is aligned with the narrower locating ring to prevent interference between the backing plates when the one torque transmitting mechanism is engaging. The backing plate of the other torque transmitting mechanism is limited in axial movement by the wider locating ring which prevents contact between the backing plate and the narrow locating ring, thus preventing interference between the backing plates when the other torque transmitting mechanism is engaging.

Locating ring and groove configuration for use with axially stacked torque transmitting mechanisms in a power transmission

A control for a multi-speed transmission has a multiple gain trim valve that controls the engagement pressure rise in a selectively engageable torque transmitting mechanism. The trim valve has a valve spool and a plug valve longitudinally aligned in a valve bore such that four separate areas are present. One of the areas has the engagement pressure of the torque transmitting mechanism imposed thereon. Another of the areas has a control pressure imposed thereon and the remaining two areas are subjected to the trim pressure. The gain rate between the trim pressure and the engagement pressure determines the rapidity with which the torque transmitting mechanism is engaged. The control pressure reduces the effect of the trim pressure to provide a low gain rate until the product of the trim pressure and one of the areas is equal to or greater than the product of the control pressure and the area on which it operates. By reducing the control pressure to a zero value, a maximum gain rate is attained at the trim valve.

Multiple gain trim valve for a selectively engageable friction device

A pressure control valve system for a friction device has a regulator valve with a plurality of pressure feedback differential areas which are selectively pressurized during the engagement of a friction device to control the apply pressure at one rate during normal operation and at a higher rate during high torque demand operation. A plug valve is disposed adjacent the regulator valve to establish two variable control forces acting on the regulator valve in response to a variable control pressure. The combination of the differential areas and the plug valve permit the regulator valve to establish two distinct pressure gain functions, each of which has a knee or inflection point resulting in two pressure gain ratios.

Pressure control valve

Power transmissions incorporate gear ratios including a plurality of forward ratios, a neutral condition and at least one reverse ratio. The establishment of each ratio is controlled by selectively engageable hydraulically operated friction devices, such as clutches and brakes. The interchange between forward ratios is controlled by the interchange of at least one friction device. The control elements to accomplish the establishment and interchange of the ratios include a pressure source, shift valve, solenoid control valves and pressure control valves. The solenoid valves are electrically actuated and the hydraulic portion of the control includes elements that permit continued operation of the transmission in selected ratios in the event of electrical discontinuance. Also provided within the hydraulic control is a pressure knockdown or pressure reducing valve element which operates with one of the shift valves to establish a maximum pressure level in the forward ratios that is less than the maximum pressure level in the reverse ratio.

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Plainfield, IN, United States of America

Jeffrey J Cole