Hybrid Vehicle Control Device Lockup State Management
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Solution Overview
Problem
Existing hybrid vehicle control methods fail to reliably pull out of a lockup state, particularly when the torque produced by the first motor-generator reaches its maximum value, leading to potential overheating and component damage.
Innovation Solution
A control device and method that includes a rotational speed detecting unit, a lockup state detecting unit, and a torque adjustment unit to decrease engine torque when a lockup state is detected, allowing the first motor-generator to exit the lockup state while maintaining fuel efficiency, and optionally includes a recovery process to change the rotational speed if the lockup state persists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lockup state pull-out torque is set larger to cause the motor-generator to pull out of the lockup state promptly, then the motor-generator can exit the lockup state faster, but the torque produced by the first motor-generator may already reach maximum torque making it impossible to increase torque further
Solution Approach 1:
The invention introduces a third element (the other motor-generator or the engine) as an intermediary to assist in pulling the first motor-generator out of the lockup state. When the first motor-generator cannot increase torque to exit lockup, the system uses the other motor-generator to provide additional torque through the power split device, effectively using an intermediary component to solve the torque deficiency.
Solution Approach 2:
The invention makes the power split device serve multiple functions: it not only transmits power from the engine to the transmitting member but also enables torque exchange between the two motor-generators. This multi-functionality allows the system to use the other motor-generator as a torque source to help pull the first motor-generator out of lockup state.
2Productivity
If the rotational speed of the first motor-generator passes over 0 rpm in a state where maximum torque is produced, then the vehicle can be accelerated further, but the motor-generator enters the lockup state (extremely low-speed area) where control fails
Solution Approach 1:
The invention applies preliminary anti-action by detecting the approaching lockup state (when rotational speed approaches 0 rpm) and taking preventive measures before the lockup state is fully established. The control system detects the tendency toward lockup and adjusts torque distribution in advance to prevent the motor-generator from entering the unreliable extremely low-speed area.
Solution Approach 2:
The invention uses feedback control by continuously monitoring the rotational speed of the first motor-generator and adjusting the torque production of the other motor-generator accordingly. When the rotational speed approaches the lockup area, the feedback mechanism triggers torque adjustment to maintain control reliability while preserving acceleration capability.
Data Source
AI summary
In a hybrid vehicle that includes an engine and a motor-generator connected to the engine through a power split device, upon acceleration in a running state, there may arise a case where the rotational speed of the MG1 enters a lockup area and, then, the MG1 cannot pull out of the lockup state with ease in such a manner that the rotational speed of the MG1 is shifted from a normal rotation area to a reverse rotation area, in accordance with an increase of a torque produced by the MG1. In this case, the engine is controlled such that a torque produced by the engine is decreased. Thus, the rotational speeds of the engine and MG1 are reduced entirely, so that the MG1 can pull out of the lockup state without increasing the torque produced by the MG1 any more.