Fuel Injection Timing Control Using Variable Standby Periods
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Solution Overview
Problem
Existing fuel injection timing methods in internal combustion engines, particularly in engines with a large number of cylinders, face challenges in accurately calculating fuel injection intervals due to the presence of a tooth missing portion on the signal rotor, which can lead to incorrect setting of fuel injection timing.
Innovation Solution
A fuel injection control apparatus that includes a signal rotor with tooth portions and a tooth missing portion, where the control unit calculates fuel injection timing by measuring inter-signal time periods and adjusts the standby time period based on whether the injection timing is set within or outside the tooth missing zone, ensuring accurate timing even in engines with multiple cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the fuel injection timing is calculated using the conventional method based on the reference tooth portion and standby period, then the fuel injection timing can be determined for normal operating conditions, but the calculation becomes inaccurate when the injection timing falls within the tooth missing zone in engines with a large number of cylinders
Solution Approach 1:
The patent applies dynamics by making the standby period variable rather than fixed. The control unit dynamically adjusts the standby period based on the detected crankshaft rotational speed. When the rotational speed changes, the standby period is recalculated to maintain accurate fuel injection timing. This dynamic adjustment resolves the contradiction by allowing the system to adapt to different operating conditions while maintaining measurement precision.
Solution Approach 2:
The patent changes the parameter of standby period from a fixed value to a variable that depends on crankshaft rotational speed. By monitoring the rotational speed and adjusting the standby period accordingly, the system maintains accurate fuel injection timing calculation across different engine speeds and cylinder configurations, including engines with a large number of cylinders where the injection interval is short.
2Speed
If the standby period is shortened to accommodate short fuel injection intervals in engines with many cylinders, then the injection timing can be responded to faster, but the standby period becomes insufficient for accurate timing calculation when the crankshaft rotational speed is low
Solution Approach 1:
The system dynamically adjusts the standby period based on real-time crankshaft rotational speed detection. When rotational speed is high, the standby period is shortened to maintain fast response. When rotational speed is low, the standby period is extended to ensure accurate timing calculation. This dynamic adaptation resolves the contradiction between response speed and measurement accuracy.
Solution Approach 2:
The standby period parameter is changed from a fixed value to a variable that scales with crankshaft rotational speed. The control unit calculates the appropriate standby period based on the detected rotational speed, ensuring that the timing calculation remains accurate across the full range of engine operating speeds while maintaining appropriate response characteristics.
3Loss of information
If the tooth missing portion is used to provide a reference signal for fuel injection timing, then the reference position can be detected, but the detection zone of the tooth missing portion requires different timing settings from normal tooth portions
Solution Approach 1:
The control unit is designed to universally handle both normal tooth portions and the tooth missing portion using the same fundamental timing calculation method. By detecting crankshaft rotational speed and calculating the standby period based on this speed, the system applies a unified approach that works for both reference types, reducing the complexity of timing settings while maintaining reference position detection capability.
Solution Approach 2:
The crankshaft rotational speed acts as an intermediary parameter that mediates between the tooth missing portion detection and the fuel injection timing calculation. Instead of requiring different timing settings for different tooth types, the system uses rotational speed as a common basis to calculate the appropriate standby period, simplifying the control logic while maintaining accurate timing.
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
This solution allows for precise calculation and adjustment of fuel injection timing, improving the accuracy and efficiency of fuel injection in engines with varying cylinder counts, particularly those with pilot or post injections, by utilizing inter-signal time periods and tooth missing zone considerations.
Implementation Method 1
a magnet pickup coil... Along a circumference of the signal rotor, a plurality of tooth portions are arranged with uniform angular spacing. Also, at one portion of the circumference of the signal rotor, a tooth missing portion formed removing tooth portions.
Data Source
AI summary
A fuel injection control apparatus is provided with a fuel injection nozzle, a crank angle detector, a timer, and a control computer. The crank angle detector outputs a pulse signal corresponding to each tooth portion of a signal rotor and a pulse signal corresponding to a tooth missing portion. The control computer sets, as a fuel injection timing, a point of time at which a predetermined standby time period has elapsed from a point of time at which a reference tooth portion is detected. The control computer recognizes a tooth missing zone based on the pulse signal corresponding to the tooth missing portion. The control computer determines whether the fuel injection timing is set in a specific section in the tooth missing zone. When the fuel injection timing is set in a section outside the specific section, the control computer sets, as the predetermined standby time period, a remaining time period shorter than one inter-signal time period. In contrast, when the fuel injection timing is set to the specific section, the control computer sets, as the predetermined standby time period, a time period obtained by adding one or more inter-signal time periods to the remaining time period.