Electronic transmission gear change control system

US4073203A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Bert Wurst · Asperg, DE
• Harald Vogt · Karlsruhe, DE

Key dates

• Filing date: Oct 10, 1975
• Grant date: Feb 14, 1978
• Expiry date: Oct 10, 1995

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16H61/10
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

To provide for precise shifting of gears in automatic transmissions in dependence on vehicle speed and loading on the engine, a speed signal and a throttle position signal are applied to separate control stages one to control up-shifting and the other to control down-shifting; further, a separate kick-down switch is provided for rapid down-shifting. The control stages are so arranged that up-shifting is commanded in accordance with vehicle operating characteristics, but down-shifting is commanded only with a lag, or hysteresis, with respect to the vehicle speed, to prevent excessive shifting of the transmission. The shift control circuits may be either separate trigger circuits controlling up-shifting and down-shifting of the respective gear ranges, or may be separate networks processing the respective input signals (speed, engine loading) and providing output control signals to a shift control trigger circuit.