Glow Plug Insulating Sleeve Design

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Solution Overview

Problem

Existing glow plug designs require complex assembly and materials, including compacted insulating powder, which increases manufacturing costs and complexity.

Innovation Solution

A simplified glow plug design that eliminates the need for insulating powder by using an electrically conductive connector with a support collar and insulating sleeve, ensuring reliable electrical conductivity between the heating cartridge and center electrode, and employing a frustoconical collar for force distribution and a laser welding process for assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If compacted insulating powder is used to establish electrical connection and hold position, then reliable electrical insulation is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveelectrical insulation reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the compacted insulating powder from the glow plug structure entirely. Instead, it uses an insulating sleeve made of ceramic or plastic material that provides electrical insulation without requiring compacted powder, thereby simplifying manufacturing while maintaining insulation reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the physical state of the insulating material from compacted powder to a solid sleeve structure. This parameter change eliminates the need for powder compaction processes and simplifies assembly while maintaining effective electrical insulation

Inventive Principle:
Principle #35Parameter changes

2Reliability

If threaded rod and metal spring assembly is used for electrical connection, then reliable electrical contact is achieved, but manufacturing steps and part count increase

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the electrical connection function and mechanical support function into a single integrated structure. The insulating sleeve with its support collar provides both electrical insulation and mechanical support for the heating element, eliminating the need for separate threaded rod and metal spring components

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The insulating sleeve is designed to perform multiple functions simultaneously: it provides electrical insulation, mechanical support for the heating element, and structural positioning within the glow plug. This multi-functionality reduces the total number of parts needed in the assembly

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces manufacturing steps and costs while maintaining effective electrical conductivity and mechanical strength, ensuring a reliable and economical glow plug with reduced risk of short circuits.

Implementation Method 1

the collar is frustoconical in cross section. With this frustoconical cross-section of the collar, it is possible to distribute the forces well over a significant support surface

Methodology Applied
Scientific EffectPressure distribution:

Implementation Method 2

employing a frustoconical collar for force distribution and a laser welding process for assembly

Methodology Applied
Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentEP3189273B1Glow plug
Publication Date: 2018.08.15 ROBERT BOSCH GMBH
  • EP3189273B1 patent drawingFigure 1
  • EP3189273B1 patent drawingFigure 2A
  • EP3189273B1 patent drawingFigure 2B

AI summary

Glow plug containing a heating pin (2) comprising a metal cover (21) and a ceramic heating cartridge (22), which is welded to the front area (101) of a tubular body (1), the back area of which carries a connector (3) for power supply. The electrical connection between the bottom wall (24) of the heating cartridge (22), which is provided with an input contact (233), the circuit of the cartridge and the front end (72) of the central electrode, contains an electrically conductive connecting piece (4) and an electrically conductive cylindrical head (6) which is attached to the front area of the central electrode (7), wherein both these two parts are pressed together between the heating cartridge and a support shoulder (103) in a depression (102) of the front end of the tubular body (1).