Hybrid Vehicle Torque Control Preventing Engine Overspeed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid vehicles, during power-on shift-down actions of automatic transmissions, the overspeeding of engines can lead to component durability issues and a strange feeling for drivers due to insufficient reduction in output torque, especially when the chargeable electric power of the storage device is limited.
Innovation Solution
A control apparatus that includes a hybrid control portion to manage input torque, a racing determining portion to predict and prevent engine overspeeding by limiting output torque, and an output limiting portion to set predetermined torque limits based on the state of the electric storage device, change in engine speed, and vehicle speed, ensuring the rotating state of the automatic transmission's input rotary member aligns with target values without causing engine overspeed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output torque of the motor/generator is reduced to make the rotating state of the input rotary member coincide with the target value during power-on shift-down, then the rotating state control is improved, but the engine may overspeed which deteriorates component durability and causes strange feeling to the driver
Solution Approach 1:
The control apparatus predicts the engine rotating speed before the power-on shift-down action is fully executed, and preliminarily limits the engine output torque when overspeeding is predicted. This preventive approach prevents the harmful effect of engine overspeeding before it occurs, while still allowing the motor/generator torque to be adjusted for proper transmission input rotating state control.
Solution Approach 2:
The control apparatus introduces an intermediate prediction and limitation mechanism between the motor/generator torque reduction and the engine rotating state. By predicting the engine speed response and limiting torque as an intermediary step, the system achieves both precise rotating state control and prevents engine overspeeding harmful effects.
2Reliability
If the chargeable electric power of the electric storage device is insufficient, then the output torque of the motor/generator cannot be sufficiently reduced, but reducing it further would cause the rotating state of the input rotary member to deviate from the target value
Solution Approach 1:
The control apparatus dynamically adjusts the control strategy based on the chargeable electric power state of the electric storage device. When chargeable power is insufficient, the system predicts and limits engine torque to compensate for the inability to sufficiently reduce motor/generator torque, maintaining rotating state control reliability under varying energy availability conditions.
Solution Approach 2:
The control apparatus changes the control parameters based on the electric storage device's chargeable power state. By monitoring the chargeable electric power and adjusting the torque limitation threshold accordingly, the system maintains reliable rotating state control whether the electric storage device has sufficient or insufficient chargeable power.
3Power
If the engine rotating speed is raised to consume surplus power as inertia power, then the input torque to the automatic transmission can be reduced as necessary, but the engine overspeeding occurs which deteriorates component durability
Solution Approach 1:
The control apparatus applies preliminary anti-action by predicting the engine rotating speed before the power-on shift-down and limiting the engine output torque in advance when overspeeding is predicted. This counteracts the tendency toward engine overspeeding before it can occur, protecting component durability while still achieving the necessary input torque reduction through coordinated motor/generator control.
Data Source
AI summary
A control apparatus for a vehicle includes a control portion configured to control an input torque to an automatic transmission such that a value representing a rotating state of an input rotary member of the automatic transmission coincides with a target value; a racing determining portion configured to determine whether a rotating speed of an engine is predicted to exceed a predetermined rotating speed when control is provided such that the value representing the rotating state of the input rotary member of the automatic transmission coincides with the target value during a power-on shift-down action of the automatic transmission; and an output limiting portion configured to limit the output torque of the engine to a predetermined torque or less if the rotating speed of the engine is predicted to exceed the predetermined rotating speed during the power-on shift-down action of the automatic transmission.