Variable Valve Mechanism Advancement for Low-Temperature Engine Start
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
At extremely low temperatures, the startability of an engine equipped with a motorized variable valve operating mechanism is compromised due to reduced electric power from a low-temperature battery, leading to slow operation of the variable valve mechanism and prolonged engine startup times.
Innovation Solution
The engine control apparatus initiates the variable valve operating mechanism's advancement prior to cranking, ensuring the intake valve timing is advanced before starting cranking, thereby ensuring startability even under low-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the variable valve operating mechanism is driven toward the advancement side after the start of cranking in low-temperature startup, then the intake valve timing is advanced to improve combustion, but the operating speed of the mechanism falls due to low battery temperature, causing the mechanism to fail to reach the needed position before combustion starts
Solution Approach 1:
The control apparatus drives the variable valve operating mechanism toward the advancement side before starting cranking when low temperature is detected. This preliminary action ensures that the intake valve timing is advanced to the needed position before combustion begins, compensating for the slow operating speed caused by low battery temperature. The timing is advanced in advance of cranking so that the mechanism reaches the target position timely despite reduced operating speed.
2Use of energy by moving object
If the variable valve operating mechanism operates slowly at low temperature, then the battery preserves its limited power, but the mechanism cannot advance the intake valve timing sufficiently before combustion starts
Solution Approach 1:
The system performs the valve timing advancement before cranking starts, when the battery still has adequate power reserves. This timing ensures that the limited electric power available at low temperature is used efficiently to achieve the necessary advancement before combustion begins, rather than attempting to catch up after cranking has already started and power reserves are depleted.
Solution Approach 2:
The control apparatus detects the temperature of the battery and engine coolant, and based on these feedback signals, determines whether to advance the valve timing before cranking. When low temperature is detected, the system activates the preliminary advancement strategy; otherwise, it uses the conventional approach of advancing timing after cranking starts.
3Reliability
If cranking is delayed to allow the variable valve operating mechanism to advance the timing first, then the intake valve timing is properly advanced, but the overall engine startup time is prolonged
Solution Approach 1:
The system advances the valve timing in advance of cranking by detecting low temperature conditions and initiating the advancement process before the cranking command is executed. This ensures that the timing advancement and cranking operations are coordinated so that the mechanism reaches the target position before combustion begins, without significantly delaying the overall startup process.
4Productivity
If the intake valve timing is not advanced sufficiently at low temperature, then the mechanism operates within its capabilities, but air filling rates and combustion efficiency deteriorate
Solution Approach 1:
By advancing the valve timing before cranking starts when low temperature is detected, the system ensures that the intake valve timing reaches the needed advancement position before combustion begins. This preliminary action compensates for the slow operating speed and ensures sufficient timing advancement to maintain acceptable air filling rates and combustion efficiency despite the reduced operating speed of the mechanism.
Data Source
AI summary
If an engine coolant temperature is equal to or lower than a first low-temperature determination value and a battery temperature is equal to or lower than a second low-temperature determination value when a request to start up an engine is made, the advancement driving of a variable valve operating mechanism is first started. Then, when an advancement amount of the variable valve operating mechanism later becomes equal to or larger than a prescribed startup start determination value, is started.