Engine Torque Control During Fuel-Cut Recovery With EGR Correction
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Solution Overview
Problem
Existing engine control systems face challenges in managing torque shocks during restoration from fuel cut due to excessive air supply during EGR learning/diagnosis, leading to unstable combustion and driver discomfort.
Innovation Solution
An engine controller that includes an exhaust gas recirculation valve, fuel injection device, and ignition device, with a processor that calculates and adjusts torque by controlling the EGR valve, throttle, and ignition timing to balance air supply and reduce torque shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EGR learning/diagnosis is performed during fuel cut, then the EGR device can be diagnosed and learned, but excessive air is supplied into the cylinder causing torque level difference and torque shock during restoration from fuel cut
Solution Approach 1:
The controller performs preliminary calculations of correction torque and EGR valve opening degree before actual restoration from fuel cut occurs. By pre-computing these values based on detected air flow rates and predetermined maps, the system prepares compensation data in advance that will be applied immediately upon restoration, preventing torque shock before it occurs.
Solution Approach 2:
The system continuously monitors the air flow rate through the EGR valve during fuel cut and uses this feedback to calculate correction torque. The detected air flow rate is fed back to the controller, which then computes the necessary torque correction and EGR valve adjustment to compensate for excessive air supply, creating a closed-loop control system that adapts to actual conditions.
2Object-generated harmful factors
If retard control of ignition timing is applied during restoration from fuel cut, then torque shock is alleviated, but engine torque becomes insufficient when EGR learning/diagnosis has caused excessive air supply
Solution Approach 1:
The system dynamically adjusts multiple parameters simultaneously: ignition timing is retarded to reduce torque shock, while correction torque is calculated and applied to compensate for power loss. The EGR valve opening degree is also adjusted based on predetermined maps. This multi-parameter coordination allows the system to reduce torque shock without sacrificing engine torque, as the correction torque counteracts the retarding effect of ignition timing change.
Data Source
AI summary
An engine controller includes an exhaust gas recirculation valve, a fuel injection device, an ignition device, and a controller including a processor. The processor includes a requested torque setter, a surplus torque setter, a comparator, and a correction torque setter. The requested torque setter sets requested torque, on the occasion of restoration from fuel cut. The surplus torque setter sets, on the occasion of the restoration from the fuel cut, surplus torque in combustion based on a flow rate of the air to pass through the exhaust gas recirculation valve. The comparator makes a comparison between the requested torque and the surplus torque. The correction torque setter sets, based on a result of the comparison, correction torque to correct the amount of the air to pass through a throttle valve and to make retard correction of ignition timing.