Apparatus for controlling concurrent releasing and engaging actions of frictional coupling devices for shifting vehicle automatic transmission

A shift control apparatus for controlling an automatic transmission of a motor vehicle having an engine, said transmission having a plurality of operating positions and including two hydraulically operated frictional coupling devices one and the other of which are released and engaged, respectively, to effect a clutch-to-clutch shift of said transmission from one of said operating positions to another of said operating positions, said shift control apparatus comprising (a) excessive engine speed preventing means for preventing a rise of a speed of said engine above an upper limit, (b) hydraulic control means for regulating hydraulic pressures of said two frictional coupling devices such that an amount of overshoot of said speed of the engine is held within a predetermined range during a period of said clutch-to-clutch shift, and (c) learning overshoot control means for effecting learning compensation of at least one of said hydraulic pressures as regulated by said hydraulic control means, when said amount of overshoot of the speed of said engine is outside said predetermined range, said shift control apparatus further comprising:

• engine state detecting means for detecting an operating state of said engine during said clutch-to-clutch shift of said transmission;
• and
• inhibiting means for inhibiting an operation of said learning overshoot control means, if said operating state of said engine detected by said engine state detecting means is expected to cause activation of said excessive engine speed preventing means during said clutch-to-clutch shift of said transmission.

A shift control apparatus for controlling an automatic transmission of a motor vehicle having an engine, said transmission having a plurality of operating positions and including two hydraulically operated frictional coupling devices one and the other of which are released and engaged, respectively, to effect a clutch-to-clutch shift of said transmission from one of said operating positions to another of said operating positions, said shift control apparatus comprising (a) excessive engine speed preventing means for preventing a rise of a speed of said engine above an upper limit, and (b) learning overshoot control means for effecting learning compensation of at least one of hydraulic pressures of said two frictional coupling devices such that an amount of overshoot of said speed of the engine is held within a predetermined range during a period of said clutch-to-clutch shift, said shift control apparatus further comprising:

• engine state detecting means for detecting an operating state of said engine during said clutch-to-clutch shift of said transmission;
• and
• hydraulic controlling and inhibiting means for inhibiting an operation of said learning overshoot control means, if said operating state of said engine detected by said engine state detecting means is expected to cause activation of said excessive engine speed preventing means, said hydraulic controlling and inhibiting means regulating said at least one of said hydraulic pressures of said two frictional coupling devices on the basis of a learning compensation value obtained by said learning overshoot control means, when said amount of overshoot of the speed of said engine is outside said predetermined range, if said operating state of said engine detected by said engine state detecting means is not expected to cause the activation of said excessive engine speed preventing means.

A shift control apparatus for controlling an automatic transmission of a motor vehicle having an engine, said transmission having a plurality of operating positions and including two hydraulically operated frictional coupling devices one and the other of which are released and engaged, respectively, to effect a clutch-to-clutch shift of said transmission from one of said operating positions to another of said operating positions, said shift control apparatus comprising (a) excessive engine speed preventing means for preventing a rise of a speed of said engine above an upper limit, (b) clutch-to-clutch shift control means for regulating hydraulic pressures of said two frictional coupling devices during a period of said clutch-to-clutch shift of said transmission, and (c) learning compensation means for effecting learning compensation of at least one of said hydraulic pressures as regulated by said clutch-to-clutch shift control means so as to reduce an amount of overshoot of the speed of said engine during said period of said clutch-to-clutch shift, said shift control apparatus further comprising:

• engine speed detecting means for detecting said speed of said engine during said clutch-to-clutch shift of said transmission;
• and
• engine output reducing means for reducing an output torque of said engine if the speed of said engine detected by said engine speed detecting means has exceeded a predetermined threshold which is not higher than said upper limit above which said excessive engine speed preventing means is activated.

A shift control apparatus for controlling an automatic transmission of a motor vehicle having an engine, said transmission having a plurality of operating positions and including two hydraulically operated frictional coupling devices one and the other of which are released and engaged, respectively, to effect a clutch-to-clutch shift of said transmission from one of said operating positions to another of said operating positions, said shift control apparatus comprising (a) excessive engine speed preventing means for preventing a rise of a speed of said engine above an upper limit, (b) hydraulic control means for regulating hydraulic pressures of said two frictional coupling devices such that an amount of overshoot of said speed of the engine is held within a predetermined range during a period of said clutch-to-clutch shift, and (c) learning overshoot control means for effecting learning compensation of at least one of said hydraulic pressures as regulated by said hydraulic control means, when said amount of overshoot of the speed of said engine is outside said predetermined range, said shift control apparatus further comprising:

• determining means for determining whether said excessive engine speed preventing means is in operation;
• and
• inhibiting means for inhibiting an operation of said learning overshoot control means, if said determining means determines that said excessive engine speed preventing means is in operation.