Variable Valve Timing Power Routing for Low Battery Start
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Solution Overview
Problem
Conventional variable valve operating devices fail to adequately vary the open and close timings of intake and exhaust valves in internal combustion engines, especially at low battery charge levels or low engine temperatures, leading to insufficient combustion energy generation.
Innovation Solution
The implementation of a variable valve operating device with multiple power supply routes, including a low voltage accumulator and an external power source, controlled by a controller that switches between these routes based on battery state and engine temperature to ensure adequate power supply to the valve-driving motor, allowing for appropriate valve timing adjustments during engine start-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the low voltage accumulator is used to supply power to the valve-driving motor, then the system is simple and reliable under normal conditions, but the valve timing cannot be adequately varied when the battery charge level is low
Solution Approach 1:
The power supply system is designed with multiple power sources (low voltage accumulator and external power source) that can interchangeably supply power to the valve-driving motor. The controller selectively switches between these power sources based on battery charge level, enabling the system to maintain valve timing variation capability under both normal and low battery charge conditions.
2Device complexity
If the valve timing is not varied at low battery charge levels, then the power supply system remains simple, but the combustion energy generation becomes insufficient
Solution Approach 1:
The power supply configuration is made dynamic by introducing a controller that monitors battery charge level and selectively connects the external power source to the valve-driving motor when the battery charge is low. This dynamic adjustment ensures sufficient power for valve timing variation and combustion energy generation only when needed, without permanently increasing system complexity.
3Reliability
If the external power source is always connected to the valve-driving motor, then adequate power is always available, but the system complexity increases and the low voltage accumulator becomes unnecessary
Solution Approach 1:
The power supply system is segmented into two distinct power sources: the low voltage accumulator for normal operation and the external power source for supplementary power when needed. The controller segments the power supply function by selectively activating the external power source only when battery charge level is low, avoiding the need for always-connected complex wiring while ensuring power availability when required.
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
Enables effective variation of valve timings even at low battery charge levels or low engine temperatures, ensuring sufficient combustion energy generation and reliable engine start-up by utilizing alternative power sources when the low voltage accumulator is insufficient.
Implementation Method 1
a first route constructed to supply an electric power from a low voltage accumulator to the valve-driving motor, where the low voltage accumulator is capable of storing a low voltage obtained by stepping down a high voltage supplied from a high voltage power source by means of an electric power conversion circuit
Data Source
AI summary
In a hybrid vehicle, on a start of an engine, when an engine water temperature is low and there is a need of advancing open and close timings of an intake valve from their most delayed positions, electric power is supplied to a WT motor either via a first route or via a second route. Even when the state of charge of a low voltage battery is very low and insufficient, the required electric power is supplied from a DC-DC converter to the VVT motor without passing through the low voltage battery. On the start of the engine, such start control ensures an adequate change of the open and close timings of the intake valve set in the stop state of the engine.