Fuel Injection Nozzle Insulating Guide for Centring Accuracy
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Solution Overview
Problem
Conventional fuel injection nozzles face challenges in accurately centring the needle within the nozzle body, leading to potential electrical contact before full engagement and inaccurate timing signals due to expansion under high pressure, which complicates machining and affects control precision.
Innovation Solution
An electrically insulating guide assembly is introduced, separate from the nozzle body and needle, to centre the needle accurately, using a non-conductive material or coating, and a compression spring to maintain contact with the profiled seat, ensuring precise alignment and preventing premature electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If machining processes are used to form guiding regions on the needle or nozzle body, then centring function is provided, but manufacturing complexity and difficulty increase
Solution Approach 1:
A separate guiding region component is introduced as an intermediary element between the needle and nozzle body. This component can be pre-formed with precise centring features and then assembled into the final assembly, transferring the manufacturing precision requirement to a dedicated part rather than requiring complex machining of the main components.
Solution Approach 2:
The guiding function is segmented from the main needle and nozzle body structures. Instead of forming guiding regions directly on these components through machining, the guiding function is provided by a separate, dedicated component that can be manufactured independently with appropriate precision and then assembled.
2Reliability
If the nozzle body expands under high pressure, then fuel injection function is maintained, but needle centring accuracy deteriorates
Solution Approach 1:
The guiding function is separated from the pressure-bearing nozzle body structure. A dedicated guiding component is introduced that is not primarily responsible for containing pressure, allowing it to maintain its geometric precision and centring accuracy even when the nozzle body expands under high pressure conditions.
Solution Approach 2:
The guiding region is designed to maintain a constant geometric relationship with the needle throughout the pressure cycle. By providing guidance through a separate component that remains dimensionally stable, the system ensures that centring conditions remain constant (equipotential) regardless of pressure-induced expansions in the main body.
3Reliability
If electrical insulation is provided between needle and body, then false timing signals are prevented, but device complexity increases
Solution Approach 1:
The guiding region component is designed to perform multiple functions simultaneously: providing mechanical guidance for needle centring and providing electrical insulation between the conductive needle and body. By merging these two functions into a single component, the solution prevents false timing signals without significantly increasing device complexity.
Solution Approach 2:
The separate guiding region component serves as a multi-functional element: it provides mechanical guidance for accurate needle centring during reciprocation and simultaneously acts as an electrical insulator to prevent premature electrical contact and false timing signals. This universal component addresses multiple problems with a single design element.
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 centring accuracy, maintains alignment under pressure, and prevents false timing signals by ensuring the needle engages the seat correctly, improving the control and operational reliability of the fuel injection nozzle.
Implementation Method 1
a compression spring arranged to bear on the needle and arranged to bias the needle into contact with the profiled seat
Implementation Method 2
an electrically insulating guide assembly including a guide which abuts the seat throughout reciprocating movement of the needle
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An injection nozzle (21) for an internal combustion engine, the nozzle (21) comprising an elongate hollow body (23) and a needle (22) arranged to reciprocate within the hollow body (23) to permit fuel to be dispensed from at least one aperture (28) at a distal end (27) of the body (23), the distal end of the body (23) defining a profiled seat (25) against which the needle (22) is 10 arranged to bear to seal the nozzle (21), characterised in that the injection nozzle (21) further comprises: an electrically insulating guide assembly including a guide (31) which abuts the seat (25) throughout reciprocating movement of the needle (22) so as to centre the distal end (24) of the needle (22) within the body (23) as needle movement is guided, the electrically insulating guide assembly being arranged to insulate the needle (22) electrically from the body (23) when the needle (22) is disengaged from the seat (25).