Apparatus and method for controlling creep torque in a power train of a motor vehicle

A power train for use in a variable-speed motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming prime mover arranged to transmit torques of different magnitudes and having inoperative and operative conditions including an idling condition;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated variable-temperature torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit including means for monitoring the temperature of said system, means for monitoring a first parameter including the speed of the motor vehicle, means for monitoring the magnitude of the torque being transmitted by said prime mover, and means for monitoring at least one further parameter of the motor vehicle, said control unit being arranged to transmit to said at least one actuator signals which initiate and effect a crawling movement of the motor vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value as a function of at least one of (a) at least one of said monitored parameters, (b) said monitored magnitude of torque being transmitted by said prime mover, and (c) a preselectable value, said amount of torque transmission by said system including a maximum amount which is a function of the monitored temperature of said system.

A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming variable-RPM prime mover having inoperative and operative conditions including an idling condition;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the motor vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value, said signal transmitting means including means for monitoring the RPM of said prime mover at least while the motor vehicle is crawling and said control unit being arranged to increase said amount of transmission while the RPM of said prime mover is above a predetermined threshold value.

A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming variable-RPM prime mover having inoperative and operative conditions including an idling condition;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value, said signal transmitting means comprising means for monitoring the RPM of said amount of torque transmission while the motor vehicle is crawling and said control unit being arranged to increase said at least one first value while the RPM of said prime mover is above a first threshold value and to at least slightly reduce the rate of torque transmission when the RPM of said prime mover decreases below a second threshold value.

A power train for use in a motor vehicle, said power train comprising:

• an energy consuming prime mover having inoperative and operative conditions including an idling condition;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value within a predetermined period of time, wherein said second value corresponds to an amount of torque transmission at which the motor vehicle begins to carry out said crawling movement.

A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming prime mover having inoperative and operative conditions;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmission system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said at least one second value as a function of time, said control unit being further arranged to set said amount at a predetermined third value in response to a termination of the application of said at least one brake prior to a reduction of said amount all the way to zero.

A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming prime mover having inoperative and operative conditions;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle, by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake and in the inoperative condition of said energy supplying means to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said amount of torque transmission from said at least one second value as a function of time, said control unit being further arranged to set said amount back to said second value in response to a termination of the application of said at least one brake prior to a reduction of said amount of torque transmission to zero.

A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

• an energy consuming prime mover having inoperative and operative conditions;
• means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;
• a transmission shiftable into and from a plurality of gears;
• an automated torque transmitting system connected with at least one of said prime mover and said transmission;
• and
• means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake and in the inoperative condition of said energy supplying means to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said at least one second value toward zero, said control unit being further arranged to change said amount to a maximum permissible third value in response to a termination of the application of said at least one brake prior to reduction of said at least one second value all the way to zero.

A method of operating a power train in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, the power train comprising an energy consuming prime mover having inoperative and operative conditions including an idling condition, means for supplying energy to the prime mover, said energy supplying means having idle and operative conditions, a transmission shiftable into and from a plurality of gears, an automated variable-temperature torque transitting system connected with at least one of said prime mover and said transmission, and means for operating said system including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from the control unit, and means for transmitting signals to the control unit including means for monitoring the temperature of said system, comprising the steps of:

• shifting the transmission in gear;
• causing the prime mover to assume the operative condition;
• maintaining the at least one brake in the non-applied condition;
• causing the energy supplying means to assume the inoperative condition;
• and as a result of shifting the transmission in gear, causing the control unit to transmit to the at least one actuator signals which effect a crawling movement of the motor vehicle by way of the power train to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value as a function of monitored temperature of said system.