vehicle control device

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of torque shock caused by restart of an engine while saving fuel consumption amount of the engine in a vehicle control device that performs engagement of a lock-up clutch and fuel cut of the engine during deceleration traveling of a vehicle.SOLUTION: During deceleration traveling of a vehicle, a lock-up clutch is engaged and fuel cut is started. When an engine speed is below an LC disengagement engine speed threshold value, the lock-up clutch is disengaged. Subsequently, when the engine speed is below an FC termination engine speed threshold value, the fuel cut is terminated. In response to decline in a cooling water temperature of the engine, the LC disengagement engine speed threshold value is increased, and in response to the decline in the temperature, the FC termination engine speed threshold value is increased. Since the increase amount of the LC disengagement engine speed threshold value is made larger than that of the FC termination engine speed threshold value, sufficient time from the disengagement of the lock-up clutch to the termination of the fuel cut can be secured, so as to prevent occurrence of torque shock.

Description

technical field [0001] The present invention relates to a vehicle control device for cutting fuel consumption of an engine by engaging a lock-up clutch when the vehicle is decelerating. Background technique [0002] According to the following patent document 1, the following technology is known, that is, when the accelerator pedal is fully closed and the vehicle enters the deceleration state, the lock-up clutch is engaged to cut off (fuel cut) the fuel supply to the engine, thereby relying on the reverse transmission from the drive wheel The driving force maintains the engine speed at a speed higher than the idle speed, and when the engine speed is below a predetermined value, the lock-up clutch is released to end the fuel cut, so that the engine can be restarted without stalling and shifted to idle speed run. [0003] As above, the lock-up clutch is engaged during the fuel cut-off process of the engine to maintain the engine speed through the driving force reversely transm...

AI Technical Summary

Problems solved by technology

However, if the LC release engine speed threshold NE LC If it is set higher, the original vehicle speed should be lower than the LC release speed threshold V when the warm-up is completed. LC While releasing the lock-up clutch, the engine speed is lower than the LC release engine speed threshold NE before this time. LC while the possibility of the lockup clutch being released

As a result, the drive force cannot be reversely transmitted from the drive wheels due to the release of the lock-up clutch, and the engine speed decreases, so that the fuel cut ends immediately, the engine is restarted, and the period during which the fuel cut is present is shortened, resulting in insufficient reduction in fuel consumption. problem of effect

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