Controller for Phase Shift Determination in Common Rail Fuel Systems
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Solution Overview
Problem
In vehicles with common rail fuel supply systems, accurately determining the phase shift between the plunger in the pump and the piston in the internal combustion engine is challenging due to noise in fuel pressure changes, leading to difficulties in matching the phase shift to a specific value during pump attachment, which increases manufacturing and component costs.
Innovation Solution
A controller is designed with a waveform obtaining unit to measure the pressure waveform of the fuel in the rail over time and a phase shift obtaining unit that calculates the phase shift based on the waveform's shape, reducing the influence of noise and allowing accurate determination of the phase shift without relying on specific timing points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the phase shift is determined based on specific timing points in fuel pressure changes, then the measurement process is simplified, but noise in fuel pressure changes reduces measurement precision
Solution Approach 1:
The patent extracts the essential characteristic of the phase shift by comparing the overall waveform shapes rather than relying on specific timing points. This extraction method isolates the relevant information (waveform shape correlation) from the noisy background, achieving both ease of operation and measurement precision.
Solution Approach 2:
The patent performs preliminary waveform acquisition and storage before phase shift determination. By pre-acquiring the fuel pressure waveforms during pump operation and storing them in memory, the system prepares clean reference data that can be compared later without being affected by real-time noise, thus improving measurement precision while maintaining operational simplicity.
2Measurement precision
If precise matching of phase shift during pump attachment is required, then measurement precision is improved, but manufacturing cost and component cost increase
Solution Approach 1:
The patent enables the system to self-determine the phase shift by automatically comparing waveform shapes after pump attachment. The controller acquires waveforms, compares their shapes, and calculates the phase shift without requiring manual intervention or precise pre-matching during assembly. This self-service approach maintains high measurement precision while dramatically simplifying the manufacturing and attachment process.
Solution Approach 2:
The patent changes the approach from fixed timing-point comparison to flexible waveform shape comparison. By using the overall shape characteristics of the pressure waveforms rather than specific parameter values at predetermined times, the system achieves robust phase shift determination that is insensitive to manufacturing variations, thereby reducing costs while maintaining precision.
3Device complexity
If the phase shift is determined using traditional timing-point methods, then device complexity is reduced, but reliability of phase shift determination decreases due to noise influence
Solution Approach 1:
The patent introduces waveform shape comparison as an intermediary method between the raw noisy pressure signals and the final phase shift value. By using the overall waveform shapes as intermediaries for comparison, the system filters out high-frequency noise while preserving the essential phase relationship information, thereby improving reliability without significantly increasing device complexity.
Data Source
AI summary
A vehicle includes a pump configured to discharge a fuel by reciprocating a plunger, a rail configured to store the fuel discharged from the pump, and a fuel injection valve configured to inject the fuel supplied from the rail. A controller for the vehicle includes a waveform obtaining unit and a phase shift obtaining unit. The waveform obtaining unit is configured to obtain a waveform of a fuel pressure in the rail as a function of time in a predetermined period. The phase shift obtaining unit is configured to obtain a phase shift based on the waveform obtained by the waveform obtaining unit. The phase shift is an offset between a timing the plunger reciprocated in the pump arrives at a first position and a timing a piston reciprocating in an internal combustion engine arrives at a second position.