Closed loop clutch slip control system with turbine roughness control
First Claim
1. In a motor vehicle including a torque converter adapted to receive engine torque through an input member thereof and to supply torque to the vehicle drivetrain through an output member thereof, a clutch mechanism connected between the input and output members of said torque converter, the clutch mechanism being operative when fully engaged to prevent slip between such input and output members, and when less than fully engaged to permit slip between such input and output members, and a clutch actuating mechanism for controlling the torque capacity of said clutch in relation to the fluid pressure supplied thereto, a method of operating said clutch mechanism so as to avoid the passage of engine torque perturbations therethrough, comprising the steps of:
- defining a desired slip signal corresponding to a desired level of clutch slippage for isolating engine torque perturbations from the output member of said clutch, an actual slip signal corresponding to the actual level of clutch slippage, and a slip error signal in accordance with the difference between the actual and desired slip signals;
controlling the fluid pressure supplied to the clutch actuating mechanism so as to drive the slip error signal to zero, and thereby maintain the actual clutch slippage at the desired level;
measuring the speed variation of the torque converter output member;
establishing a predetermined threshold speed variation for the output member in accordance with the output speed, such threshold defining a level of output member speed variation above which the clutch is deemed to be transmitting an excessive amount of engine torque perturbation; and
when the measured variation exceeds the threshold speed variation, reducing the slip error signal in relation to the measured speed variation in a direction such that the fluid pressure supplied to the clutch control chamber is decreased to permit clutch slippage to be controlled to a higher level than the desired level.
1 Assignment
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Accused Products
Abstract
The net engagement pressure of a torque converter clutch is controlled in response to a commanded slip and a slip error indication, for isolating engine torque perturbations from the vehicle driveline. The transmission of an excessive level of engine speed perturbation is detected and used to develop a correction amount for the measured slip. The correction amount increases the slip error indication and causes the slip to be controlled at a higher level, thereby reducing the amount of transmitted engine torque perturbation.
61 Citations
6 Claims
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1. In a motor vehicle including a torque converter adapted to receive engine torque through an input member thereof and to supply torque to the vehicle drivetrain through an output member thereof, a clutch mechanism connected between the input and output members of said torque converter, the clutch mechanism being operative when fully engaged to prevent slip between such input and output members, and when less than fully engaged to permit slip between such input and output members, and a clutch actuating mechanism for controlling the torque capacity of said clutch in relation to the fluid pressure supplied thereto, a method of operating said clutch mechanism so as to avoid the passage of engine torque perturbations therethrough, comprising the steps of:
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defining a desired slip signal corresponding to a desired level of clutch slippage for isolating engine torque perturbations from the output member of said clutch, an actual slip signal corresponding to the actual level of clutch slippage, and a slip error signal in accordance with the difference between the actual and desired slip signals; controlling the fluid pressure supplied to the clutch actuating mechanism so as to drive the slip error signal to zero, and thereby maintain the actual clutch slippage at the desired level; measuring the speed variation of the torque converter output member; establishing a predetermined threshold speed variation for the output member in accordance with the output speed, such threshold defining a level of output member speed variation above which the clutch is deemed to be transmitting an excessive amount of engine torque perturbation; and when the measured variation exceeds the threshold speed variation, reducing the slip error signal in relation to the measured speed variation in a direction such that the fluid pressure supplied to the clutch control chamber is decreased to permit clutch slippage to be controlled to a higher level than the desired level. - View Dependent Claims (2)
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3. In a motor vehicle including a torque converter adapted to receive engine torque through an input member thereof and to supply torque to the vehicle drivetrain through an output member thereof, a clutch mechanism connected between the input and output members of said torque converter, the clutch mechanism being operative when fully engaged to prevent slip between such input and output members, and when les than fully engaged to permit slip between such input and output members, and a clutch actuating mechanism for controlling the torque capacity of said clutch in relation to the fluid pressure supplied thereto, a method of operating said clutch mechanism so as to avoid the passage of engine torque perturbations therethrough, comprising the steps of:
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defining a desired slip signal corresponding to a desired level of clutch slippage for isolating engine torque perturbations from the output member of said clutch, an actual slip signal corresponding to the actual level of clutch slippage, and a slip error signal in accordance with the difference of the actual and desired slip signals; supplying fluid pressure to the clutch actuating mechanism in accordance with the magnitude and sign of the slip error signal so as to maintain the actual clutch slippage at the desired level; cyclically determining a sample of the speed of the torque converter output member and generating an output speed variation signal according to the difference between successively determined speed samples; establishing a predetermined threshold speed variation for the output member in accordance with the engine speed, such threshold defining a level of output member speed variation above which the clutch is deemed to be transmitting an excessive amount of engine torque perturbation; updating an output roughness signal in proportion to the difference between the output speed variation signal and the threshold speed variation when the output speed variation signal exceeds the threshold speed variation; determining a slip error correction amount in relation to the output roughness signal; and adjusting the slip error signal by the slip error correction amount such that the slip error signal indicates reduced slippage to thereby effect an adjustment in the fluid pressure supplied to the clutch actuating mechanism which permits clutch slippage in excess of the desired level, whereby the level of engine torque perturbation transmitted through the clutch is reduced. - View Dependent Claims (4, 5, 6)
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Specification