Fuel Injector Throttle Gap Reduces Pin Wear
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Solution Overview
Problem
Existing fuel injectors for internal combustion engines require high manufacturing accuracy and wear resistance for the pin region to maintain sealing, which is challenging and costly, and results in limited tolerance for manufacturing variations.
Innovation Solution
A fuel injector design featuring a pressure chamber with a nozzle needle that has a cone region and a pin region of constant diameter, interacting with a conical nozzle needle seat and a blind hole, creating a throttle gap that reduces contact and wear, allowing for larger manufacturing tolerances and efficient fuel supply through adjustable throttle gap sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pin region performs a sealing function by projecting into the blind hole, then sealing accuracy is improved, but manufacturing precision requirements increase and wear resistance becomes critical
Solution Approach 1:
The patent introduces a throttle gap as an intermediary element between the pin region and the blind hole wall. This gap prevents direct contact between the pin region and the seat, eliminating the sealing function from the pin region while maintaining fuel flow control. The throttle gap acts as a mediator that allows fuel passage without requiring precise sealing contact.
Solution Approach 2:
The patent extracts the sealing function from the pin region and transfers it to the cone region interacting with the conical nozzle needle seat. The pin region is relieved of its sealing duty and now only serves as a flow control element through the throttle gap. This separation of functions reduces the manufacturing precision requirements for the pin region.
2Reliability
If the pin region maintains contact with the blind hole wall for sealing, then sealing function is improved, but wear increases and manufacturing tolerances must be tight
Solution Approach 1:
The throttle gap serves as a permanent intermediary space between the pin region and the blind hole wall, preventing direct contact. This eliminates the need for tight manufacturing tolerances to ensure proper sealing, as the sealing function is now performed by the cone region at the nozzle needle seat interface, which has larger acceptable tolerances.
3Manufacturing precision
If the throttle gap is reduced to increase throttling effect, then fuel control precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the throttle gap dimensions to achieve the desired balance between throttling effect and manufacturing feasibility. By carefully selecting the gap width parameters, the design achieves sufficient fuel flow control for small quantities while maintaining compatibility with standard manufacturing tolerances, avoiding the need for ultra-precise machining.
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 design achieves reduced wear and manufacturing accuracy requirements while maintaining a suitable injection characteristic for small fuel quantities, enabling smoother transitions between engine loads and improved engine power output with reduced risk of axial misalignments and wear.
Implementation Method 1
At least during a partial stroke of the nozzle needle, the first injection opening and the second injection opening are connected to one another via a throttle gap, which is formed in the blind hole between the pin region and the wall of the blind hole
Implementation Method 2
The cone region of the nozzle needle interacts with the nozzle needle seat and thereby opens and closes the first injection opening and the second injection opening with respect to the pressure chamber
Data Source
AI summary
The invention relates to a fuel injector for internal combustion engines for injecting fuel at high pressure, comprising a pressure chamber formed in an injector body, in which pressure chamber a nozzle needle is arranged in a longitudinally movable manner, which nozzle needle has a cone region tapered in a combustion chamber direction and a pin region having a constant diameter d23 at a combustion-chamber end of the nozzle needle. The injector body has a substantially conical nozzle needle seat, from which a first injection opening extends, and a blind hole, which adjoins the nozzle needle seat on the combustion chamber side. The blind hole has a cylindrical segment, which has the diameter d31, and a hole base, from which a second injection opening extends. The cone region of the nozzle needle interacts with the nozzle needle seat and thereby opens and closes the first injection opening and the second injection opening with respect to the pressure chamber. During a partial stroke of the nozzle needle, the first injection opening and the second injection opening are connected to each other by means of a throttle gap, which is formed in the blind hole between the pin region and the wall of the blind hole, and the throttle gap remains constant at least over the partial stroke of the nozzle needle.