Allison Transmission, Inc.

Torotrak (development) Limited

John William Edward Fuller

Charles Francis Long

Darren J Weber

Stephen William Murray

Christopher John Greenwood

Stephen Murray

An apparatus for multiplexing gear engagement control in an automatic transmission is provided. At least two friction engagement devices are configured to selectively engage and disengage a different gear ratio of the transmission. A trim system is configured to selectively supply engagement and disengagement pressures to at least one fluid passageway. A first control valve is fluidly coupled directly to the at least one fluid passageway and directly to each of the at least two friction engagement devices. The first control valve is configured to selectively route the engagement and disengagement pressures through the first control valve directly to the at least two friction devices.

System and method for multiplexing gear engagement control and providing fault protection in a toroidal traction drive automatic transmission

A transmission includes an electro-hydraulic controller that includes redundancy in the hydraulic circuit that permits single fault failures to be compensated for by changing the flow path of hydraulic fluid to bypass the single fault failure. The redundancy results in the ability of the transmission to maintain full operation in all modes.

Multi-plexing clutch logic control of a multi-mode transmission

Variator control with torque protection

Redundant controls for a multi-mode transmission

Cold operation mode control for an IVT

A variator lockout valve system for a continuously variable transmission includes a pair of shift valves. Each shift valve has at least one port that is fluidly coupled to a variator of the continuously variable transmission. Electro-hydraulic actuators control the position of each of the shift valves. When the shift valves are in one position, pressure control valves supply fluid pressure to the variator. If one of the shift valves is in another position, one of the pressure control valves is blocked from supplying fluid pressure to the variator.

Variator lockout valve system

A fault diagnostic method for an automatic transmission may include monitoring an operating state of a trim system configured to selectively supply clutch engagement pressure and exhaust to at least one clutch control valve, determining an expected operating state of the trim system based on current operating conditions of the transmission, and generating a fault signal if the monitored operating state of the trim system is different from the expected operating state of the trim system.

System and method for detecting clutch-related faults in an automatic transmission

A fail-to-neutral diagnostic technique for a transmission that includes a variator may include monitoring a state of a pressure differential valve fluidly coupled to a high side pressure applied to at least one actuator coupled to at least one corresponding roller of the variator and also fluidly coupled to a low side pressure applied to the at least one actuator, determining from the state of the pressure differential valve a variator torque sign corresponding to whether torque transferred by the at least one roller is positive or negative, determining an expected variator torque sign based on current operating conditions of the transmission, and commanding the transmission to a true neutral condition if the determined variator torque sign is different from the expected variator torque sign.

Fail-to-neutral system and method for a toroidal traction drive automatic transmission

The invention concerns an electronic controller for a continuously variable transmission of the type having a variator () with a rotary variator input () coupled to a first variator race () and a rotary variator output () coupled to a second variator race (). At least one roller () runs upon the said races to transfer drive from one to the other. The roller is movable to steplessly vary the variator ratio. The variator further comprises at least one hydraulic actuator (), () which acts upon the roller and through which net torque acting on the variator races is referred via the roller to the variator's casing. A hydraulic arrangement is provided for applying to the actuator at least one hydraulic control pressure which determines force applied' by the actuator and thus determines the reaction torque. The variator is coupled between a rotary transmission input () and a rotary transmission output () such that the transmission ratio is a function of the variator ratio. The electronic controller is adapted to cany out the following steps in a loop: measure a speed ratio of the continuously variable transmission; compare the measured speed ratio with a target speed ratio; determine a transmission output torque request on the basis of the said comparison; convert the output torque request to a control pressure request, taking account of the speed ratio; differentiate the control pressure request with respect to lime to obtain a compensation value and apply the compensation value to the control pressure request; and output the resulting compensated control pressure request to the hydraulic valve arrangement.

Electronic controller for a continuously variable transmission and a method of control of a continuously variable transmission

The invention concerns an arrangement for controlling a vehicle drivetrain having an engine provided with a speed governor and a continuously variable transmission ('CVT') incorporating a variator which is constructed and arranged to regulate its reaction torque. The control system comprises a control part () movable by the driver to provide a driver input, an open loop subsystem () for operatively coupling the control part to the governor () to control no-load speed of the governor in dependence on the driver input, a closed loop subsystem comprising a comparator () which receives a first control signal deprived from the driver input and corresponding to a target engine speed, and a second control signal corresponding to engine speed, and which adjusts variator reaction torque in dependence upon a comparison of the first and second control signals causing the transmission to load the engine suitably to achieve the target engine speed.

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Preston, United Kingdom

John William Edward Fuller