Injector Needle Position Detection via Electromagnetic Induction
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Solution Overview
Problem
Conventional techniques cannot accurately detect the position of a movable part in an injector at valve closed timing, leading to inaccurate fuel injection and potential sealability issues due to wear, which results in premature replacement of injectors.
Innovation Solution
A detection system using a detection circuit and microcomputer that applies a low-frequency application voltage to the application coil, generating an induced voltage in the detection coil based on the magnetic permeability changes between the needle and cylinder, allowing for precise detection of the needle's position at valve closed timing through changes in detection voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection methods are used, then the valve closed timing can be detected, but the position of the movable part at valve closed timing cannot be detected
Solution Approach 1:
The patent replaces mechanical position detection methods with electromagnetic induction. A detection coil generates an alternating magnetic field that interacts with the movable part (needle), and changes in magnetic permeability due to position changes are detected as voltage changes in the coil. This substitution enables non-contact, high-precision position detection at valve closed timing without mechanical wear or contact interference.
Solution Approach 2:
The patent utilizes changes in magnetic permeability parameter of the movable part (needle) as it moves through different positions. By detecting the induced voltage changes in the detection coil caused by varying magnetic permeability, the system can determine the precise position of the movable part at valve closed timing. This parameter-based detection method converts mechanical position information into electrical signal variations.
2Reliability
If injectors are replaced based on conventional detection, then premature replacement may occur, but accurate position detection is lost
Solution Approach 1:
The patent implements a feedback mechanism where the detection coil continuously monitors the position of the movable part at valve closed timing. The control unit receives the detection signal and compares it against reference values to determine if the needle has worn or shifted position. This feedback loop enables real-time assessment of injector condition, allowing operators to extend injector service life until actual wear compromises performance, rather than following fixed replacement schedules.
3Manufacturing precision
If no position detection is implemented, then manufacturing costs are lower, but injection accuracy deteriorates
Solution Approach 1:
The detection coil serves multiple functions: it generates the alternating magnetic field for detection, acts as the sensor for position detection, and provides the electrical connection for signal transmission to the control unit. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while enabling precise position detection and maintaining injection accuracy.
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
Enables accurate detection of the needle's position change at valve closed timing, preventing premature replacement and maintaining injection control accuracy until the injector's sealability is compromised, thus optimizing replacement timing and reducing manufacturing costs.
Implementation Method 1
a detection system using a detection circuit and microcomputer that applies a low-frequency application voltage to the application coil, generating an induced voltage in the detection coil based on the magnetic permeability changes between the needle and cylinder
Implementation Method 2
generating an induced voltage in the detection coil based on the magnetic permeability changes between the needle and cylinder, allowing for precise detection of the needle's position at valve closed timing through changes in detection voltage
Data Source
AI summary
An injection control device includes an injector and a detection unit. The injector includes: an injection hole; a movable part; a seat portion; a valve housing; a magnetic field application unit; and a detection sensor. The movable part opens and closes the injection hole by reciprocal movement. The seat portion when seated by the movable part closes the injection hole, and when the movable part lifted therefrom opens the injection hole. The valve housing accommodates the movable part in a reciprocally movable manner. The magnetic field application unit is installed on an outer circumference of the valve housing and applies a magnetic field to the movable part and the valve housing. The detection sensor outputs a detection signal according to a size of a distance between the valve housing and the movable part.