Gm Global Technolgoy Operations, Inc.

Fereydoon Jamzadeh

Joseph H Hunter

Arthur L Grew, Jr

Goetz William Schaefer

The present invention provides a method for automatic downhill speed control or ADSC adapted to automatically absorb grade-induced energy so that the vehicle operator is no longer required to take action to maintain generally constant vehicle speed. ADSC is preferably triggered if the throttle is released and the vehicle accelerates. The specific amount of throttle release necessary to trigger ADSC is variable but may, according to a preferred embodiment, be set at 85% throttle reduction. According to another preferred embodiment, ADSC is not triggered unless the throttle is released for a predetermined amount of time such as, for example, 5 seconds.

Vehicle speed control system

A method of determining the acceleration of a rotating body by counting the number of teeth on a rotating gear member for one or more revolutions. The method minimizes the measurement lag using an overlapping method and calculating acceleration on each control loop that a new revolution count is available. The method determines the new tooth count based on the tooth count estimated for the next update. The old tooth count is discarded and the new tooth count is adjusted to match the old tooth count within the system constraints to provide less interrupts and faster acceleration updates. The number of gear revolutions to be counted are increased at higher gear speeds.

Acceleration processing method and apparatus

A powertrain for a vehicle includes an engine, a multi-speed transmission and control, and output drive mechanisms. The transmission has an electro-hydraulic control for establishing the transmission drive ratios and the interchange therebetween. The ratios are established by a plurality of friction devices, one of which is engaged for the lowest forward ratio. The control has a microcomputer which evaluates vehicle operating parameters and maintains the transmission properly controlled in response to various input signals. The transmission is maintained in an auto neutral condition when the engine is at idle, the transmission output speed is zero, the vehicle brakes are engaged and the forward drive has been selected. The control continually adjusts the pressure in the one friction device to maintain the torque capacity thereof in a range less than full engagement and greater than a minimum value.

Automatic transmission auto neutral clutch controls with intermittent

An automatic shifting power transmission has at least two selectively engageable devices which provide distinct gear ratios when engaged during normal operation. These devices are pressure released and mechanically engaged by springs to establish tie-up in the transmission when the hydraulic pressure is not present. This tie-up provides a parking condition in the transmission by preventing rotation of the transmission output member.

Parking brake for a power transmission

In a computer-based control, pressure is progressively decreased in an off-going clutch for gradual release while pressure is progressively increased in an on-coming clutch. Positive off-going clutch slip and the rate of slip change are monitored to detect the onset of turbine flare. A control calculates a compensation pressure which is added to the on-coming clutch pressure to reduce the slip and thus the flare. The control calculates a term proportional to slip and an integral term when the slip and slip rate are positive. When the slip rate goes negative, the control calculates a negative integral term. All the calculated terms are combined to produce the compensation pressure value.

Anti-flare method using offgoing slip speed and rate of change of

A braking system for a vehicle. The braking system provides continuous tactile feed back through the brake pedal to the operator of the vehicle that conforms to the degree to which the vehicle brakes are being applied so that the tactile feed-back to the operator conforms to the visual and kinesthetic input received by the operator. The braking system has a brake pedal that is mounted to be depressed in response to a force applied thereto by the vehicle operator. The braking system incorporates both a mechanical brake actuating mechanism and a hydraulic brake actuating mechanism. The braking system provides for selective actuation of the mechanical brake actuating mechanism sequentially in advance of the hydraulic brake actuating mechanism when the brake pedal is depressed. A linkage assembly is incorporated in the mechanical brake actuating mechanism. The linkage assembly provides tactile feed-back to the brake pedal throughout the range of operation of said braking system. Subsequent to the mechanical actuation of the braking system, continued depression of the brake pedal actuates the hydraulic brake actuating mechanism. This sequencing is provided by a brake actuating system embodying the concepts of the present invention and is responsible for the reliable tactile feed-back reflected in the brake pedal.

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Indianapolis, IN, United States of America

Fereydoon Jamzadeh