Lock-up Clutch Slip Control Torque Management
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Solution Overview
Problem
Conventional vehicle lock-up control methods experience engagement shock and judder due to rotation peeling when the engine torque exceeds the lock-up capacity during accelerator pedal depression, especially before lock-up clutch engagement.
Innovation Solution
A vehicle lock-up control method that reduces engine torque below normal levels when the slip rotational speed reaches a predetermined value during slip control, preventing the engine torque from exceeding the lock-up capacity by executing engine torque reduction control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If accelerator pedal depression increase operation is carried out immediately before lock-up clutch engagement, then engine torque increases to meet driver demand, but engine torque exceeds lock-up capacity causing rotation peeling and engagement shock
Solution Approach 1:
The control device detects accelerator pedal depression increase before lock-up clutch engagement and preemptively reduces engine torque output. This preliminary action prevents the engine torque from exceeding the lock-up capacity during the critical engagement phase, avoiding rotation peeling and ensuring smooth clutch engagement while still allowing the clutch to engage successfully.
2Reliability
If engine torque reduction control is executed when slip rotational speed reaches predetermined value, then rotation peeling is prevented, but driver-requested torque is reduced
Solution Approach 1:
The control device changes the engine torque parameter dynamically based on the slip rotational speed parameter. When the slip rotational speed reaches a predetermined value indicating imminent engagement, the engine torque is reduced to prevent exceeding lock-up capacity. After successful engagement, the torque reduction is released to restore full driver-requested torque output, thus maintaining engagement stability while minimizing impact on power delivery.
3Stability of the object's composition
If lock-up capacity is gradually increased during slip control, then smooth engagement is achieved, but engagement time is extended
Solution Approach 1:
The control device executes preliminary engine torque reduction before the lock-up clutch engagement is complete, when the slip rotational speed reaches a predetermined value. This timing allows the lock-up capacity to continue increasing gradually for smooth engagement while the engine torque is already reduced, preventing the need for further delays. The coordinated timing of these actions achieves both smooth engagement and reasonable engagement duration.
Data Source
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AI summary
To prevent occurrence of engagement shock and judder during a slip control of the lock-up control, even if an accelerator pedal depression increase operation is carried out immediately before the lock-up clutch is engaged. According to the present invention, an engine-equipped vehicle comprises a torque converter (4) that has a lock-up clutch (3) and that is arranged between an engine (1) and a continuously variable transmission (6). In this engine-equipped vehicle, when an engagement request of the lock-up clutch (3) is issued, an initial-motion lock-up control is executed, whereby engagement is achieved through slip control that increases the lock-up capacity and gradually reduces the slip rotational speed, which is the input-output differential rotational speed of the lock-up clutch (3). During the slip control of the initial-motion lock-up control, if the slip rotational speed enters a smooth ON control region that is at or below a first set value N1, a second engine torque reduction control that reduces the torque of the engine (1) below the normal torque that is applied in response to a driver's request is executed.