Hybrid Vehicle Engine Start Control via Wheel Locking
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Solution Overview
Problem
Low temperatures increase the load on electric motors and decrease battery voltage, making it difficult to start internal combustion engines in hybrid vehicles, leading to gear-contact noise between the parking lock gear and pawl due to alternating torque directions.
Innovation Solution
A vehicle driving apparatus with a controller that executes lock switching control to forcibly lock wheels and release the driveshaft, allowing the engine to be started by a motor, and cancels wheel locking after engine self-driving begins, with temperature-dependent cranking control to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor cranks the engine at low temperature, then the engine can be started, but the battery voltage decreases and the load on the electric motor increases, making it difficult to start the engine
Solution Approach 1:
The brake device is activated before engine cranking to lock the wheels, preventing torque reversal and preparing the system for stable motor-driven cranking at low temperatures
2Reliability
If the electric motor starts the engine at low temperature, then the engine can be cranked, but the alternating torque direction causes vibrations and gear-contact noise
Solution Approach 1:
The brake device is activated in advance before engine cranking to lock the wheels, preventing torque reversal that causes parking lock gear contact and noise
Solution Approach 2:
The brake device applies a counteracting force by locking the wheels before cranking, preventing the harmful torque reversal and vibrations that would otherwise occur during engine starting
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces gear-contact noise during engine starting, enhancing occupant comfort by ensuring smooth engine cranking and reducing vibrations.
Implementation Method 1
a brake device for locking the wheels
Implementation Method 2
a motor for starting the engine
Data Source
AI summary
When the condition for starting an engine (50) is satisfied, the controller (90) executes the lock switching control in which the wheels (88) are forcibly locked by the brake device (86) and the parking lock mechanism (200) is released to unlock the driveshaft (step S4, step S5), and then the controller (90) executes the cranking control (step S6) in which the engine (50) is started by the motor-generator (MG1).