Method for controlling engine start in a vehicle
First Claim
1. A method for starting an engine in a vehicle having an electric machine, a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine, and a second clutch disposed between the electric machine and vehicle drive wheels, the second clutch being selectively engagable for facilitating torque transfer between the electric machine and the vehicle drive wheels, the method comprising:
- requesting an engine start;
operating the electric machine;
facilitating slip in the second clutch, thereby at least partially isolating the vehicle drive wheels from engine torque disturbances;
engaging the first clutch with a rapid fill to bring a pressure of the first clutch to a first level;
reducing the pressure of the first clutch to a second level, the second level being defined by a first function;
reducing the pressure of the first clutch to a third level;
controlling the pressure of the first clutch in accordance with a pressure profile until there is at least substantially no slipping in the first clutch; and
fueling the engine, thereby facilitating torque production by the engine.
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Accused Products
Abstract
A vehicle includes a motor/generator, a disconnect clutch disposed between the engine and the motor/generator, and a transmission disposed between the motor/generator and the vehicle drive wheels. The transmission includes an input clutch which is selectively engagable for facilitating torque transfer between the motor/generator and the vehicle drive wheels. When an engine start is requested, the motor/generator is operated, and a start mode for the engine is determined based on a number of vehicle parameters. The transmission input clutch is partially disengaged to at least partially isolate the vehicle drive wheels from engine torque disturbances when the engine is started. The disconnect clutch is engaged, and the engine is fueled, thereby facilitating torque production by the engine.
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Citations
18 Claims
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1. A method for starting an engine in a vehicle having an electric machine, a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine, and a second clutch disposed between the electric machine and vehicle drive wheels, the second clutch being selectively engagable for facilitating torque transfer between the electric machine and the vehicle drive wheels, the method comprising:
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requesting an engine start; operating the electric machine; facilitating slip in the second clutch, thereby at least partially isolating the vehicle drive wheels from engine torque disturbances; engaging the first clutch with a rapid fill to bring a pressure of the first clutch to a first level; reducing the pressure of the first clutch to a second level, the second level being defined by a first function; reducing the pressure of the first clutch to a third level; controlling the pressure of the first clutch in accordance with a pressure profile until there is at least substantially no slipping in the first clutch; and fueling the engine, thereby facilitating torque production by the engine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for starting an engine in a vehicle having an electric machine, a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine, and a second clutch disposed between the electric machine and vehicle drive wheels, the second clutch being selectively engagable for facilitating torque transfer between the electric machine and the vehicle drive wheels, the method comprising:
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requesting an engine start; operating the electric machine; facilitating slip in the second clutch, thereby at least partially isolating the vehicle drive wheels from engine torque disturbances; engaging the first clutch with a rapid fill to bring a pressure of the first clutch to a first level; controlling the pressure of the first clutch such that it follows a non-increasing first pressure profile after the pressure of the first clutch reaches the first level; reducing the pressure of the first clutch from the first level and controlling the pressure such that it follows a second pressure profile; controlling the pressure of the first clutch such that it follows a third pressure profile different from the second pressure profile; controlling the first clutch pressure in accordance with the third pressure profile until there is at least substantially no slipping in the first clutch; and fueling the engine, thereby facilitating torque production by the engine, and wherein operating the electric machine includes; operating the electric machine in a torque control mode until a speed of the engine is greater than a first predetermined engine speed, operating the electric machine in a speed control mode when the engine speed is greater than the first predetermined engine speed and output torque of the electric machine is not less than a predetermined output torque, the operating of the electric machine in the speed control mode effecting a reduction in the output torque of the electric machine when the engine begins to produce torque, and operating the electric machine in the torque control mode after the output torque of the electric machine is reduced by the engine beginning to produce torque. - View Dependent Claims (11, 12)
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13. A method for starting an engine in a vehicle having an electric machine, a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine, and a second clutch disposed between the electric machine and vehicle drive wheels, the second clutch being selectively engagable for facilitating torque transfer between the electric machine and the vehicle drive wheels, the method comprising:
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requesting an engine start; operating the electric machine in a torque control mode until a speed of the engine is greater than a first predetermined engine speed; operating the electric machine in a speed control mode when the engine speed is greater than the first predetermined engine speed and output torque of the electric machine is not less than a predetermined output torque, the operating of the electric machine in the speed control mode effecting a reduction in the output torque of the electric machine when the engine begins to produce torque; operating the electric machine in the torque control mode after the output torque of the electric machine is reduced by the engine beginning to produce torque; facilitating slip in the second clutch, thereby at least partially isolating the vehicle drive wheels from engine torque disturbances; engaging the first clutch, thereby connecting the engine to the electric machine; and fueling the engine, thereby facilitating torque production by the engine. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification