Hybrid Vehicle Torque Control for Smooth Power-On Shift-Down
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid vehicles, the automatic transmission's power-on shift-down action can cause a strange feeling for the driver due to stagnation of shifting progress or racing engine speed, as the first motor/generator's torque is limited, preventing it from generating the necessary torque for shifting, especially during power-on shift-down actions.
Innovation Solution
A control apparatus that controls the output torque of the first and second motor/generators based on engine torque and coupling device torque to match angular acceleration values, with a limited state determining portion and output limiting portion to ensure the engine torque is limited only when necessary during power-on shift-down actions, allowing the first motor/generator to generate the required torque for shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output torque of the first motor/generator is limited, then the motor/generator can operate within safe load boundaries, but it cannot generate sufficient torque for shifting progress during power-on shift-down actions
Solution Approach 1:
The patent dynamically changes the torque limitation parameter of the first motor/generator based on the shifting state of the automatic transmission. During power-on shift-down actions, the control apparatus temporarily increases the torque limit beyond normal operating constraints, allowing the motor/generator to generate sufficient shift-progressing torque while returning to standard limits during normal operation for safety.
Solution Approach 2:
The patent implements dynamic torque limitation adjustment rather than a fixed limit. The torque limitation is adaptively modified according to real-time transmission state, enabling the system to respond flexibly to shifting requirements while maintaining operational safety under normal conditions.
2Power
If the first motor/generator cannot generate sufficient torque during power-on shift-down, then the motor/generator operates within its limited capacity, but the shifting action stagnates and engine speed races up
Solution Approach 1:
The control apparatus temporarily modifies the torque output parameter of the first motor/generator during power-on shift-down actions by lifting the torque limitation constraint. This allows the motor/generator to output higher torque levels necessary for smooth shifting progress, preventing both stagnation and engine speed racing.
Solution Approach 2:
The system continuously monitors the shifting state and motor/generator torque output, using this feedback to dynamically adjust torque limitations. When shift stagnation or engine speed racing is detected, the feedback loop triggers temporary torque limit relaxation to restore smooth shifting operation.
3Power
If the engine torque is not limited during power-on shift-down, then sufficient power is available for vehicle acceleration, but the first motor/generator cannot handle the combined load of reaction torque and shift-progressing torque
Solution Approach 1:
The patent implements conditional parameter changes where the torque limitation of the first motor/generator is selectively adjusted based on operating conditions. During power-on shift-down, the torque limit parameter is temporarily increased to accommodate the combined load requirements, while maintaining normal torque limits during other operations to preserve vehicle acceleration performance.
Solution Approach 2:
The control apparatus proactively adjusts the torque limitation parameter before the motor/generator becomes overloaded during power-on shift-down actions. By anticipating the increased load requirement and pre-adjusting the torque limit, the system prevents reliability issues before they occur while maintaining optimal performance.
Data Source
AI summary
A control apparatus for a hybrid vehicle provided with an engine, a differential mechanism having a first rotary element to which the engine is operatively connected, a second rotary element to which a first motor/generator is operatively connected, and a third rotary element to which an intermediate power transmitting member is connected, a second motor/generator operatively connected to the intermediate power transmitting member, and an automatic transmission which constitutes a part of a power transmitting path between the intermediate power transmitting member and drive wheels and in which a shifting action is performed by selective engagement of a plurality of coupling devices, the control apparatus comprising: a hybrid control portion for controlling an output torque of the first motor/generator and an output torque of the second motor/generator during the shifting action of the automatic transmission on the basis of an output torque of the engine and a transmitted torque of the coupling devices, such that an angular acceleration value of the second motor/generator and an angular acceleration value of the engine coincide with respective target values; a limited state determining portion for determining whether the output torque of the first motor/generator is in a limited state of being limited lower than a predetermined load capable of ensuring a shift-progressing torque necessary for progress of a power-on shift-down action of the automatic transmission; and an output limiting portion for limiting the output torque of the engine to a predetermined torque or less if the output torque of the first motor/generator is in the limited state during the power-on shift-down action of the automatic transmission.