Fuel Injector Actuator Segmentation for Thermal Protection
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Solution Overview
Problem
Existing fuel injection devices for internal combustion engines face challenges in precisely controlling the valve head position and maintaining the electroactive element in optimal operating conditions due to proximity to the combustion chamber, which can lead to degradation and space constraints.
Innovation Solution
A fuel injection device with a cylindrical body and a needle actuated by an electro-active bar, where the bar is prestressed by a weight and capable of axial resonance, allowing for precise control of the valve head and efficient fuel droplet formation through vibratory movement, with the actuator positioned away from the combustion chamber to avoid heat exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electroactive element is placed in close proximity to the head to achieve fast response time, then the response time is reduced to less than 50 μs, but the element is exposed to high temperatures from the combustion chamber that can degrade its operation
Solution Approach 1:
The actuator is divided into two separate parts: a first actuator portion positioned near the head for fast response, and a second actuator portion positioned farther from the combustion chamber for thermal protection. This segmentation allows each portion to serve its specific function optimally while resolving the contradiction between proximity for speed and distance for thermal protection.
2Measurement precision
If the electroactive element is placed near the nose of the injector to control valve head position, then the valve control precision is improved, but space constraints and thermal exposure problems arise
Solution Approach 1:
The actuator is segmented into a first portion near the valve head for precise control and a second portion farther away for thermal protection, allowing both precision control and thermal management to coexist.
Solution Approach 2:
A flexible connection element (such as a flexible cable or rod) acts as an intermediary to transmit the actuation force from the protected second portion to the vulnerable first portion near the valve head, enabling precise control without direct exposure of the electroactive material to harsh conditions.
3Object-affected harmful factors
If the bar is made longer to position the actuator away from the combustion chamber, then thermal exposure is reduced, but the device complexity and space requirements increase
Solution Approach 1:
The actuator is segmented into multiple portions positioned at different distances from the combustion chamber, with the first portion near the head and the second portion farther away. This segmentation achieves thermal protection without requiring an excessively long single-bar structure, thereby controlling device complexity.
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
The solution enables precise control of the valve head with fast response times and the formation of very fine fuel droplets, while keeping the electroactive element in a favorable operating environment, improving the efficiency and reliability of the fuel injection process.
Implementation Method 1
the needle enters into axial resonance when it is subjected by the actuator to axial pulses at a determined excitation frequency, thus superimposing a vibratory movement of the head on the overall movement of the needle
Implementation Method 2
When the electroactive material is excited, it elongates, causing the elastic elongation of the needle and thus the separation of the head from the seat
Implementation Method 3
the bar is made of magnetostrictive material and is surrounded by a coil capable of creating a magnetic field in the bar. When such a material is subjected to a magnetic field, it undergoes an elongation which is transmitted to the needle
Implementation Method 4
the bar is made of piezoelectric material
Data Source
Figure 1
AI summary
The inventive fuel injecting device comprises a cylindrical body (11, 12), a needle (2) whose end is provided with a head (20) forming a valve on a seat (14) supported by the end of the cylindrical body, an actuator (3) which is made of an electroactive material, is provided with a rod and displaces the head (20) in such a way that the valve is opened and a prestressing device holding the needle and a counterweight in such a way that they are pressed against the rod opposite end. The needle (2) extends coaxially to the cylindrical body (11, 12) in the form of a rigid bar and axially resonates when it is exposed to axial pulses at a determined excitation frequency by the actuator (3). A method for controlling said device is also disclosed.