CVT Engine Torque Control for Shift Shock Reduction
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Solution Overview
Problem
Existing engine control systems for vehicles with continuously variable transmissions experience shift shock during gear shifting from the first speed stage to the second speed stage due to differences in driving force between the first and second engagement portions, leading to negative acceleration and a poor driving experience.
Innovation Solution
An engine control device that includes a continuously variable transmission mechanism and an auxiliary transmission mechanism, with shift control means that adjust the engine torque by increasing it during gear shifting from the first speed stage to the second speed stage to maintain a target transmission gear ratio, thereby reducing shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the first engagement portion is shifted from engaged state to released state and the second engagement portion is shifted from released state to engaged state during gear shifting, then the transmission gear ratio is changed from first speed stage to second speed stage, but the driving force changes to the smaller side causing negative acceleration and shift shock
Solution Approach 1:
The engine torque is increased in advance during the gear shifting process to compensate for the reduction in driving force. By performing this torque increase before and during the engagement transition, the system prevents negative acceleration and shift shock, ensuring smooth gear ratio transition from first to second speed stage.
Solution Approach 2:
The engine torque parameter is dynamically adjusted during gear shifting. By changing the engine torque from the basic engine torque to a higher value during the transition period, the system compensates for the driving force reduction caused by engagement portion switching, thereby maintaining positive acceleration and eliminating shift shock.
2Ease of operation
If the engine torque is increased during gear shifting, then the negative acceleration and shift shock are reduced, but the engine control complexity increases
Solution Approach 1:
The engine control device monitors the gear shifting state and automatically adjusts engine torque accordingly. By implementing feedback control that detects when gear shifting occurs and responds by increasing engine torque, the system improves driving experience while keeping the control mechanism automated and manageable through state-based decision logic.
Data Source
AI summary
An engine control device for a vehicle including a power train where a continuously variable transmission is coupled to an engine, includes engine torque control means configured to control the engine so as to obtain an basic engine torque corresponding to an operating state of the vehicle, and command means configured to command engine torque control means to increase an engine torque from the basic engine torque during a gear shifting from a first speed stage to a second speed stage. The continuously variable transmission includes a continuously variable transmission mechanism, an auxiliary transmission mechanism that includes at least a first engagement portion and a second engagement portion to achieve the gear shifting from the first speed stage to the second speed stage, and shift control means configured to set a target value of a transmission gear ratio of the entire continuously variable transmission mechanism and the auxiliary transmission mechanism based on the operating state of the vehicle to control the continuously variable transmission mechanism such that the target value is achieved.