Shift device for an automatic transmission

Abstract

A shift device for an automatic transmission generates no manual shift demand in response to a plurality of operator shift demands. A steering wheel has an up-down select switch. A range selector has an upshift switch and a downshift switch in addition to an automatic mode switch. An operator shift demand may be generated through any one of the steering mounted switches and the select lever. A control unit has an operator upshift demand input terminal and an operator downshift demand input terminal. The control unit has a circuit that generates a two-level up signal and a circuit that generates a two-level down signal. The up signal has an “OFF” level indicative of absence of an operator upshift demand on the operator upshift demand input terminal. It has an “ON” level indicative of presence of an operator upshift demand on the operator upshift demand input terminal. The down signal has an “OFF” level indicative of absence of an operator downshift demand on the operator downshift demand terminal. It has an “ON” level indicative of presence of an operator downshift demand on the operator downshift demand input terminal. The control unit has software, which generates an upshift demand upon a rise in level of the up signal to “ON” level if the down signal is at “OFF” level. This software enables the control unit to generate a downshift demand upon a rise in level of the down signal to “ON” level if the up signal is at “OFF” level.