Upshift control device for automatic transmission

An upshift control device for an automatic transmission of a motor vehicle wherein the transmission is shifted up to a first gear position to be established after upshifting, by releasing an oil pressure from a first engaging element that has been engaged in a second gear position established before upshifting while applying an oil pressure to a second engaging element that has been released in the second gear position, said upshift control device comprising:

• a first accumulator provided in an oil path leading to the first engaging element that is to be released upon completion of upshifting;
• an accumulator control valve for producing an oil pressure to be applied to a back pressure chamber of said first accumulator;
• a timing valve that is switched between a position to allow the oil pressure to be supplied to said back pressure chamber of said first accumulator, and a position to remove the oil pressure from the back pressure chamber;
• upshift determining means for determining whether an upshift command to shift up the transmission is generated;
• engine racing detecting means for detecting racing of an engine of the vehicle during upshifting;
• and
• engine racing preventive control means for generating to an actuator of said timing valve a command to temporarily supply the oil pressure to said back pressure chamber of said first accumulator from which the pressure has been released, when said engine racing detecting means detects racing of the engine after the upshift command is generated.