Hybrid Vehicle Control Device Engine Start Modes
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Solution Overview
Problem
Hybrid vehicles face challenges in starting the engine from a motor single driving state without interrupting power transmission, leading to potential battery charge shortages and unintended vehicle backward movement, especially at low speeds or on hills.
Innovation Solution
A control device for hybrid vehicles that includes an engine and electric motor, with multiple transmission routes and modes (push-start and motor start) to manage engine start based on vehicle speed, using clutch engagement and driving force reduction controls to optimize engine start timing and prevent backward movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the push-start mode is used to start the engine at low vehicle speeds, then the engine can be started using driving force from the driving wheels, but the vehicle may move backward on hill-climbing roads due to neutral gear position
Solution Approach 1:
The control device applies preliminary anti-action by detecting hill-climbing road conditions and preventing engagement of the first clutch in push-start mode when backward movement risk is identified. The system proactively counteracts the potential harmful effect (backward movement) before it occurs by blocking the engine start sequence under unsafe conditions, thereby resolving the contradiction between engine start reliability and prevention of unintended vehicle movement.
2Reliability
If the motor start mode is used to start the engine using motor driving force, then the engine can be started without neutral gear position, but no driving force is transmitted to the driving wheels causing potential vehicle backward movement on hills
Solution Approach 1:
The control device acts as an intermediary by introducing a hill-climbing road condition detection mechanism that mediates between the motor start mode execution and driving force transmission requirements. When hill-climbing conditions are detected, the system prevents motor start mode engagement, thereby resolving the contradiction by using the control device as an intermediary layer that balances engine start reliability with maintenance of driving force transmission.
3Ease of operation
If motor single driving is continued at vehicle speeds below the minimum push-start speed, then the vehicle can operate in electric mode, but the battery state of charge may become insufficient
Solution Approach 1:
The control device implements feedback by continuously monitoring vehicle speed and comparing it against the minimum push-start speed threshold. When the vehicle speed falls below this threshold during motor single driving, the system provides feedback that triggers a mode transition warning or automatic engine start sequence, thereby resolving the contradiction between maintaining ease of electric operation and preventing battery charge depletion through timely engine engagement.
Data Source
AI summary
A control device for a hybrid vehicle includes a push-start mode and a motor start mode. The push-start mode transmits a driving force from driving wheels to the engine via a first transmission route at a speed detected by a speed detection means equal to or more than a predetermined speed to start the engine. The motor start mode starts the engine using a driving force of the motor at a speed equal to or less than the predetermined speed as well as in a stopped state. At a speed outside a speed range that either mode is executable when a start command of the engine occurs in driving only using the electric motor as the driving source, a control means performs the driving force reduction control for reducing a driving force transmitted from the electric motor to the driving wheels of the vehicle.