CVT Control Device Engine Speed Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional control methods for vehicles with continuously variable transmissions (CVT) that aim to suppress rattling noise by increasing engine rotational speed lead to degraded fuel consumption, especially when accessory loads are low, as they often shift the engine out of the low-rotation medium-load range unnecessarily.
Innovation Solution
A control device that uses an electronic control unit to adjust the speed ratio of the CVT and engine rotational speed based on accessory load, keeping the engine at a first rotational speed when loads are low and increasing it to a second rotational speed when loads are high, thereby avoiding the low-rotation medium-load range and optimizing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotational speed of the engine is increased to suppress rattling noise, then the occurrence of rattling noise is suppressed, but the fuel consumption of the vehicle degrades
Solution Approach 1:
The control device changes the engine rotational speed parameter dynamically based on accessory load conditions. When accessory load is high, the engine speed is increased to exit the low-rotation medium-load range and suppress rattling noise. When accessory load is low, the engine speed is maintained at optimal levels to prevent unnecessary fuel consumption. This conditional parameter adjustment resolves the contradiction by applying speed increase only when truly needed.
Solution Approach 2:
The system implements dynamic control of engine rotational speed based on real-time accessory load detection. The control device continuously monitors accessory load and adjusts engine speed accordingly, transitioning between different operational states (low speed for fuel efficiency, high speed for noise suppression). This dynamic adaptation allows the system to optimize both noise suppression and fuel consumption depending on actual operating conditions.
2Object-affected harmful factors
If the rotational speed of the engine is increased constantly during air conditioner operation, then rattling noise is suppressed, but fuel consumption degrades when accessory load is actually low
Solution Approach 1:
The control device implements feedback control by continuously monitoring accessory load conditions and adjusting engine rotational speed based on actual load levels. The system detects whether accessory load is high or low and responds appropriately: increasing engine speed only when load is high (when rattling noise actually occurs), and maintaining optimal speed when load is low. This feedback mechanism eliminates the need for constant speed increase during air conditioner operation, resolving the contradiction between noise suppression and fuel efficiency.
Solution Approach 2:
The control strategy applies different engine speed control approaches based on local accessory load conditions. Instead of a uniform high-speed approach during air conditioner operation, the system applies high speed only in the specific condition where accessory load is high and rattling noise occurs. When accessory load is low, the system applies fuel-efficient speed control. This localized, condition-specific control resolves the contradiction by matching the control action to the actual local conditions.
Data Source
AI summary
A control device for a vehicle is provided. The vehicle includes an engine, an accessory, a continuously variable transmission, and a lock-up clutch. The control device includes an electronic control unit. The electronic control unit is configured to: when the load state is less than a predetermined value, control the speed ratio of the continuously variable transmission and the rotational speed of the engine such that the rotational speed of the engine during engagement of the lock-up clutch is kept at a first rotational speed; and when the load state is greater than or equal to the predetermined value, control the speed ratio of the continuously variable transmission and the rotational speed of the engine such that the rotational speed of the engine during engagement of the lock-up clutch becomes a second rotational speed higher than the first rotational speed.