Laser Ignition Housing Segmentation for Optical Axis Stability
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Solution Overview
Problem
Existing laser ignition apparatuses for internal combustion engines face challenges such as mechanical stress-induced optical axis distortion, energy loss during laser transmission, large size issues, and reliability concerns due to thermal expansion and soot deposition, leading to unstable ignition.
Innovation Solution
A laser ignition apparatus with a double-housing structure and elastic pressing mechanisms to prevent optical axis distortion, combined with a cooling device for thermal management and an optical window design to prevent soot deposition, ensuring stable and focused laser delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the housing is tightened by applying torque to the male-threaded portion, then the housing is securely fixed to the cylinder head, but torsion of the housing causes mechanical stresses in the optical elements, distorting their optical axes and making it difficult to focus the laser beam to the desired ignition point
Solution Approach 1:
The housing is divided into a proximal housing and a distal housing that are coupled together. The optical elements are contained in the distal housing, which can be tightened independently from the proximal housing. This segmentation allows the distal housing to be secured to the cylinder head without transmitting tightening torque to the optical elements, thereby maintaining optical axis alignment precision while achieving reliable fixation.
Solution Approach 2:
The distal housing acts as an intermediary between the tightening mechanism (male-threaded portion) and the optical elements. By placing the optical elements in the distal housing and coupling it to the proximal housing, the intermediary structure transmits the fixation function while isolating the optical elements from mechanical stresses during tightening, thus preserving optical axis alignment.
2Device complexity
If the optical elements are disposed in the tubular housing, then the structure is compact, but the tightening torque causes torsion and mechanical stresses that distort the optical axes
Solution Approach 1:
The housing is segmented into proximal and distal portions, with optical elements placed in the distal housing. This segmentation maintains structural compactness while allowing independent tightening of the distal housing, preventing torque transmission to optical elements and preserving optical axis alignment precision.
Solution Approach 2:
The coupling between proximal and distal housings utilizes angular offset of the male-threaded portion relative to the optical axis. This dimensional arrangement allows the tightening force to be applied in a direction that does not create torsion about the optical axis, maintaining alignment precision while achieving secure fixation.
3Device complexity
If the focusing lens is arranged in the housing with only the focusing lens and optical window member received in the housing, then the structure is simplified and mounting is facilitated, but energy loss during laser transmission via optical fiber becomes large, causing unstable ignition
Solution Approach 1:
Instead of using a single focusing lens, the invention employs multiple lenses (first lens and second lens) arranged in sequence. This copying approach creates a more efficient optical path that reduces energy loss during transmission while maintaining structural simplicity and facilitating mounting.
Solution Approach 2:
The first lens and second lens are combined in a single optical path within the housing, with the first lens receiving laser light from the optical fiber and the second lens focusing it. This merging of optical functions reduces overall energy loss compared to single-lens configurations, while the integrated structure maintains simplicity and ease of mounting.
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 ensures stable ignition by maintaining optical axis alignment, minimizing energy loss, and preventing thermal stress, while also reducing the apparatus's size and improving reliability.
Implementation Method 1
irradiate an excitation light generated by an excitation light source (e.g., a flash lamp or a semiconductor laser) to a laser resonator (or optical resonator) that includes a laser medium and a Q switch, thereby causing the resonator to generate a pulsed laser light that has a short pulse width and a high energy density
Implementation Method 2
focusing the pulsed laser light, using an optical element (e.g., a focusing lens), to a focal point (or an ignition point) in a combustion chamber of the engine to generate a flame kernel that has a high energy density
Data Source
AI summary
A laser ignition apparatus includes a housing that has a male-threaded portion for fixing the housing and a hexagonal portion for tightening the male-threaded portion. Between a combustion chamber-side end of the male-threaded portion and an anti-combustion chamber-side end of the hexagonal portion, there is defined a non-optical element arrangement region in which none of an introducing optical element, an enlarging optical element and a focusing optical element of the apparatus is arranged. At one of a combustion chamber-side end and an anti-combustion chamber-side end of the non-optical element arrangement region, there is formed a reference surface that extends perpendicular to an axial direction of the housing. One of the introducing optical element, the enlarging optical element and the focusing optical element is received in the housing in such a manner as to be elastically pressed against the reference surface from outside of the non-optical element arrangement region.