Piezo-Driven Nozzle Needle Dosing Device
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Solution Overview
Problem
Existing fuel injectors for vehicles face challenges in precise control of fuel flow rate and complexity due to the need for coupling devices between actuators and nozzle needles, which increases structural complexity and limits switching speed and precision.
Innovation Solution
A metering device with a nozzle needle that uses direct frictional contact between a piezoelectric element and the nozzle needle, eliminating the need for a coupling device, allowing for rapid flow rate changes and precise control through frictional contact, enabling precise timing and shaping of fuel injection profiles without the requirement for a spring preload or control quantity circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a coupling device is used between the actuator and nozzle needle, then the structure is more stable and easier to manufacture, but the switching speed decreases and structural complexity increases
Solution Approach 1:
The invention removes the coupling device from the system entirely. The piezoelectric actuator directly contacts the nozzle needle through frictional engagement, eliminating the intermediate coupling component. This extraction of the coupling device reduces structural complexity and eliminates the delays associated with force transmission through additional components, thereby improving switching speed.
Solution Approach 2:
The invention merges the actuator and nozzle needle into a more integrated configuration by establishing direct frictional contact between them. The piezoelectric element is positioned to directly engage the nozzle needle surface, combining what were previously separate functional elements (actuator and coupling device) into a streamlined direct-drive arrangement, reducing overall structural complexity.
2Reliability
If a coupling device is used between the actuator and nozzle needle, then the force transmission is more reliable, but the structural complexity increases
Solution Approach 1:
The coupling device is extracted from the system, and reliability is maintained through direct frictional contact between the piezoelectric actuator and nozzle needle. The large contact area and controlled normal force ensure reliable force transmission without requiring additional coupling components, thereby reducing structural complexity while maintaining or improving reliability.
Solution Approach 2:
The invention replaces the traditional mechanical coupling device with a friction-based direct contact system. Instead of using gears, linkages, or other mechanical intermediaries, the system uses controlled friction between the piezoelectric element and nozzle needle to transmit force, simplifying the mechanical structure while maintaining reliable force transmission.
3Reliability
If a spring preload is used to hold the nozzle needle in closed position, then the nozzle needle can be reliably closed, but the device complexity increases
Solution Approach 1:
The spring preload mechanism is extracted from the system. The invention uses direct frictional contact between the piezoelectric actuator and nozzle needle to hold the needle in the closed position. The piezoelectric element can maintain constant contact force without requiring a spring, and can quickly release the needle when voltage is applied, reducing device complexity while maintaining reliable closure.
Solution Approach 2:
The mechanical spring preload system is replaced with an electrostatic friction-based holding mechanism. The piezoelectric element uses electrostatic forces to maintain contact and hold the nozzle needle in position, eliminating the need for mechanical springs while improving response speed and reducing complexity.
4Ease of operation
If a coupling device is used, then the actuator can be spatially separated from the nozzle needle, but the switching speed and precision decrease
Solution Approach 1:
The coupling device is extracted, requiring the actuator to be positioned closer to the nozzle needle. This direct configuration eliminates the spatial separation and associated delays in force transmission, improving switching speed while maintaining actuator positioning flexibility through the frictional contact interface.
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 enhances switching speed and precision in fuel injection, allowing for more accurate timing programs, reducing structural complexity, and enabling the suppression of nozzle needle oscillation, thereby improving engine performance and efficiency.
Implementation Method 1
at least one piezo element (5, 6, 7) serving as an actuator for the linear movement of the nozzle needle (4) can be brought into frictional contact with the nozzle needle (4)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Metering device (1) for an electrically insulating liquid or gaseous medium (2), comprising a nozzle (3) with a nozzle needle (4), wherein the flow rate of the medium (2) through the nozzle (3) can be controlled by a linear movement of the nozzle needle (4), wherein the actuator for the linear movement of the nozzle needle (4) is at least two piezoelectric elements (5, 6; 5a, 6a) offset along the longitudinal axis (4a) of the nozzle needle (4), which can be excited to a linear change in length directed towards the outer surface (4b) of the nozzle needle (4), wherein a frictional contact between the piezoelectric elements (5, 6; 5a, 6a) and the nozzle needle (4) can be established by this change in length.is reversible and wherein the piezo elements (5, 6; 5a, 6a) are coupled to each other via a bending beam (8; 8a) running parallel to the nozzle needle (4), and/or • at least one piezo element (7; 7a) is provided which can be excited to a combination of a longitudinal expansion parallel to the longitudinal axis (4a) of the nozzle needle (4) and a bending vibration, so that an intermittent frictional contact between the piezo element (7; 7a) and the nozzle needle (4) can be established by the bending vibration.