Fuel Injector Switch Detection with High-Temperature Resistor
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Solution Overview
Problem
Injectors in internal combustion engines face challenges in accurately detecting the switching behavior due to high initial current flow when the nozzle needle is not yet lifted, leading to potential short-circuit detection errors by the electronic control unit, especially as emissions regulations tighten and components wear over time.
Innovation Solution
Incorporating a high-temperature resistor chip to limit current flow when the switch is closed, combined with a non-magnetic structure and corrosion-resistant stainless steel contacts, ensures a controlled current flow for accurate switch state detection, and a plastic encapsulation protects the resistance from environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current flows via the switch formed by the contact pairing of the nozzle needle tip and nozzle needle seat to ground potential for detecting the injector's condition, then the actual opening time can be determined and injector status can be detected, but the current flowing to ground becomes very high which may result in the electronic control unit incorrectly detecting a short circuit
Solution Approach 1:
A high-temperature resistor chip is introduced as an intermediary element in the electrical circuit between the nozzle needle seat and ground. This resistor limits the ground current to a few milliamperes, preventing false short-circuit detection by the electronic control unit while still allowing sufficient current for switch state detection. The resistor acts as a mediator that reconciles the conflicting requirements of detectability and safety.
Solution Approach 2:
The electrical resistance parameter is deliberately changed by introducing a high-temperature resistor chip with specific resistance characteristics. This changes the current flow parameter in the ground path from potentially high values to controlled milliamperage levels. The resistor's temperature coefficient and power rating are specifically selected to maintain stable resistance across the operating temperature range while limiting current appropriately.
2Device complexity
If the nozzle needle and nozzle needle seat are used as switches for detecting switching behavior, then the actual opening time can be determined in a relatively simple manner, but under certain circumstances the current flowing via the switch is very high which can cause incorrect short circuit detection
Solution Approach 1:
The high-temperature resistor chip serves as an intermediary component that maintains the simplicity of the switch-based detection system while eliminating the harmful effect of high ground current. The resistor is integrated into the existing circuit without requiring fundamental system redesign, thus preserving low complexity while improving reliability.
3Reliability
If a high-temperature resistor chip is used to limit current flow when a switch is closed, then false short-circuit detection is prevented, but the resistor must maintain stable resistance under extreme temperature fluctuations
Solution Approach 1:
The resistor chip is specifically selected with parameters optimized for high-temperature operation. The resistance value and temperature coefficient are chosen to maintain stable electrical characteristics across the extreme temperature range from -55°C to +300°C. This parameter selection ensures that the current-limiting function remains reliable regardless of thermal conditions.
Solution Approach 2:
The high-temperature resistor chip likely employs composite material construction with ceramic substrates and specialized resistive layers that maintain dimensional and electrical stability under thermal stress. This composite structure provides both the current-limiting capability and the temperature stability required for reliable operation in the injector's harsh environment.
4Volume of moving object
If the high-temperature resistor chip is designed to be compact with very small change in resistance when temperature changes, then space is saved and resistance stability is improved, but the operating temperature range must extend to extreme conditions
Solution Approach 1:
The resistor chip's physical and electrical parameters are optimized for high-temperature operation. The compact size reduces thermal mass while the material composition and construction ensure minimal resistance change across the extreme temperature range. This parameter optimization allows the small component to withstand temperatures from -55°C to +300°C without compromising 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
This solution allows for precise detection of the switch state, preventing false short-circuit detection and maintaining consistent emissions and performance parameters over the injector's lifespan, even under varying temperature and wear conditions.
Implementation Method 1
a high-temperature resistance chip (R) is provided in the line between a coil contact and a first terminal of the switch (3)
Implementation Method 2
an electromagnet, wherein the electromagnet preferably causes the nozzle needle tip to be lifted out of the nozzle needle seat when subjected to current conducted via the inlet line and the outlet line
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an injector for injecting fuel, comprising an injector housing, a movable nozzle needle, which is arranged in the injector housing and has a nozzle needle tip, and a nozzle needle seat for receiving the nozzle needle tip. A contact pairing of the nozzle needle and the nozzle needle seat constitutes a mechanical switch, which assumes a closed state when the nozzle needle tip contacts the nozzle needle seat and an open state when the contact is interrupted. Furthermore, according to the invention, the injector has an input line and an output line for controlling movement of the nozzle needle, the switch has a first terminal, which is connected to the input line, and a second terminal, which is connected to the injector housing, and a resistor is connected between the first terminal of the switch and the input line. The inventive is characterized in that the resistor is a high-temperature resistor chip.