Engine Control Device for Preventing Blowby Gas Freezing
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Solution Overview
Problem
Existing engine control systems fail to effectively prevent the freezing of condensate water in blowby gas, leading to the formation of ice blocks at connecting parts between the intake and blowby gas passages, especially at low ambient temperatures, which can damage engine components.
Innovation Solution
A control device for an engine that includes a blowby gas passage connected near the compressor of a turbocharger, where the turbocharger's boost pressure is adjusted based on ambient temperature, engine load, and oil pan water content to increase thermal energy transfer and prevent ice block formation by enhancing the temperature of the connecting parts through increased boost pressure and thermal energy from exhaust gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If exhaust gas is recirculated through the EGR passage to heat the blowby gas, then the temperature of the blowby gas is increased and condensation is suppressed, but when ambient temperature is low and combustion is unstable, exhaust gas recirculation is stopped and the heating effect is lost
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary device that transfers heat from exhaust gas to blowby gas through a thermal coupling mechanism. The heat exchanger includes a heat transfer plate where exhaust gas flows on one side and blowby gas flows on the other side, enabling heat transfer without direct mixing. This intermediary structure ensures continuous heating of blowby gas regardless of EGR valve status, maintaining reliability of ice block prevention even when combustion is unstable.
2Device complexity
If the blowby gas passage is connected far from the compressor, then the structure is simpler, but the thermal energy from the compressor cannot be utilized to prevent freezing
Solution Approach 1:
The patent positions the blowby gas passage connection point upstream of the compressor, so that blowby gas passes through the connecting part before being compressed. The compressor then heats this connecting part during compression, and this pre-heated connecting part subsequently prevents freezing when blowby gas flows through it. This preliminary heating action ensures the connecting part is already warm before the critical freezing risk occurs.
3Temperature
If boost pressure is increased continuously to maintain temperature, then thermal energy is always available, but fuel efficiency deteriorates
Solution Approach 1:
The patent implements periodic or conditional boost pressure adjustment based on detected freezing risk. The control unit monitors ambient temperature, blowby gas temperature, and other parameters to determine when freezing risk exists. Boost pressure is increased only during periods when freezing risk is detected, and returned to normal levels when the risk subsides. This periodic action maintains temperature only when necessary, preserving fuel efficiency during normal operation.
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
Effectively prevents the freezing of condensate water and formation of ice blocks at connecting parts, reducing the risk of engine component damage while minimizing the impact on fuel efficiency by only increasing boost pressure when necessary.
Implementation Method 1
thermal energy transferred to a compressor accommodating part from a turbine accommodating part heated with exhaust gas at a high temperature passing through the turbine
Implementation Method 2
the temperature of the blowby gas is increased by the exhaust gas at the high temperature flowing inside the EGR passage
Implementation Method 3
a compressor provided to the intake passage and configured to be rotary driven by the turbine to boost the intake air
Implementation Method 4
the water contained in the blowby gas is condensed and the condensate water is introduced into the intake passage. Here, when the ambient temperature is especially low, the condensate water may be cooled and frozen by the intake air at the low temperature
Data Source
AI summary
An engine control device is provided, which includes a blowby gas passage connecting an engine body to an intake passage so that blowby gas leaked from a combustion chamber is recirculated to the intake passage, a boost pressure changer configured to change a boost pressure of a turbocharger, and a controller configured to set a target boost pressure and control the boost pressure changer. The turbocharger includes a turbine which is provided to an exhaust passage and driven by exhaust gas, and a compressor which is provided to the intake passage and rotary driven by the turbine to boost intake air. The blowby gas passage is connected to the intake passage near the compressor. The controller corrects the target boost pressure when an ambient temperature is below a given determination temperature, to be higher than the target boost pressure when the ambient temperature is at or above the determination temperature.