Variable Valve Intake Control for Diesel Deposit Removal
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Solution Overview
Problem
Existing methods for removing deposits from internal combustion engine intake ports are inefficient, particularly in diesel engines, where the low combustion temperature hinders effective deposit burning, and existing techniques either fail to maximize combustion gas blow-back or compromise fuel economy and exhaust performance.
Innovation Solution
A control device and method that utilize a variable valve mechanism and external EGR system to increase combustion gas blow-back to the intake port by adjusting the intake valve lift and EGR gas recycling based on EGR gas temperature, ensuring maximum gas blow-back while maintaining optimal cylinder temperature and air-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the valve overlap method is used to blow back combustion gas to the intake port, then the deposit removal function is improved, but the combustion gas temperature decreases rapidly after combustion completion making the method ineffective for diesel engines
Solution Approach 1:
The patent employs a variable valve mechanism that dynamically adjusts the intake valve lift amount based on real-time EGR gas temperature measurements. The control unit increases the lift amount when EGR gas temperature is low to maximize combustion gas blow-back, and reduces it when temperature is high to prevent excessive cylinder temperature rise. This dynamic adjustment resolves the contradiction by adapting the valve operation to temperature conditions.
Solution Approach 2:
The patent changes the parameter of intake valve lift amount according to EGR gas temperature. By measuring EGR gas temperature and adjusting the lift amount accordingly, the system optimizes the blow-back of combustion gas to the intake port while controlling cylinder temperature, thereby effectively removing deposits in diesel engines.
2Temperature
If the intake valve is opened again in the expansion stroke to exhaust stroke to blow back high temperature combustion gas, then the deposit burning effectiveness is improved, but the amount of combustion gas blown back is limited due to three-way catalyst requirements
Solution Approach 1:
The patent merges internal EGR (combustion gas blow-back) with external EGR (exhaust gas recycling) systems. By combining both EGR mechanisms, the system can blow back sufficient amounts of combustion gas to the intake port for effective deposit burning while still meeting emission requirements through the external EGR pathway.
Solution Approach 2:
The patent creates a copied EGR pathway by introducing external EGR gas in addition to internal EGR. This allows the system to achieve the necessary total EGR gas amount for deposit removal while maintaining the equivalent ratio of 1 required by the three-way catalyst through the external EGR component.
3Object-generated harmful factors
If the amount of combustion gas blown back to the intake port is increased to burn up deposits, then the deposit removal effectiveness is improved, but the cylinder temperature rises excessively affecting fuel economy and exhaust performance
Solution Approach 1:
The patent implements a feedback control system that measures EGR gas temperature and uses this information to adjust the intake valve lift amount. The control unit continuously monitors temperature and modifies the valve operation accordingly, increasing lift when temperature is low to enhance deposit removal, and reducing lift when temperature is high to prevent excessive cylinder temperature rise, thus maintaining fuel economy and exhaust performance.
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 burns and removes deposits from the intake port by maximizing combustion gas blow-back, suppressing cylinder temperature rise, and maintaining fuel economy and exhaust performance.
Implementation Method 1
an EGR cooler 33 that cools the EGR gas
Implementation Method 2
burn up the deposit by the combustion gas
Implementation Method 3
burn up the deposit accumulated in the intake port
Data Source
AI summary
An electronic control unit executes a deposit removal operation of removing a deposit accumulated in an intake port of an internal combustion engine. In the deposit removal operation, the temperature of an EGR gas that is recycled to an intake passage is measured or estimated. Then, a variable valve mechanism is operated such that an intake valve is opened in an expansion stroke or an exhaust stroke and the lift amount of the intake valve becomes larger as the measured or estimated temperature of the EGR gas becomes lower. Further, an external EGR device is operated such that the amount of the EGR gas that is recycled to the intake passage becomes larger as the measured or estimated temperature of the EGR gas becomes lower.