Heater Plug Metal Finger Pressure Sensor Isolation
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Solution Overview
Problem
Existing heater plugs with built-in force sensors are not compatible with standard metal heater fingers due to size constraints, and they suffer from reduced heating performance and increased design and manufacturing costs when attempting to accommodate shorter ceramic fingers, leading to inaccurate pressure measurements and vibration interference.
Innovation Solution
A heater plug design featuring a tubular body with a metallic finger and a pressure sensor, where the sensor is positioned between bearing parts connected via tubular parts, allowing for relative longitudinal movement, and a membrane connected to the finger to transmit pressure independently of the finger's elasticity, with a structure that accommodates a standard 50mm long, 4mm diameter metal finger, and uses silicone gel and synthetic material fillings to minimize vibration and heat conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard metal heater finger (50mm long, 4mm diameter) is used in a heater plug with a built-in force sensor, then heating performance is maintained and manufacturing cost is reduced, but the finger's elasticity interferes with pressure measurement accuracy and the finger's vibrations adversely affect sensor readings
Solution Approach 1:
A membrane is introduced as an intermediary element between the metal heater finger and the force sensor. The membrane transmits pressure forces from the finger to the sensor while being isolated from the finger's vibrations and elastic deformations. This mediator allows accurate pressure measurement without being affected by the harmful vibrations and elasticity of the metal finger.
Solution Approach 2:
The heater plug is segmented into distinct functional zones: a fixed part containing the force sensor and membrane assembly, and a movable part containing the metal heater finger. This segmentation allows the finger to vibrate and move independently without transmitting these disturbances to the sensor, while still enabling pressure transmission through the membrane.
2Adaptability or versatility
If a shorter ceramic heater finger is designed to accommodate the force sensor structure, then the heater plug can incorporate a built-in force sensor, but heating performance decreases and design and manufacturing costs increase
Solution Approach 1:
The heater plug design allows the use of a standard, universal metal heater finger (50mm long, 4mm diameter) that can be manufactured using existing processes. The force sensor assembly is designed to accommodate this standard finger, making the sensor system adaptable to conventional heater components without requiring custom-manufactured shorter ceramic fingers.
3Device complexity
If the force sensor is placed immediately above the heater finger, then pressure measurement is simplified, but the sensor is exposed to high temperatures from the combustion chamber
Solution Approach 1:
The heater plug is divided into a fixed part containing the temperature-sensitive force sensor and a movable part containing the heater finger. This spatial segmentation separates the sensor from the high-temperature combustion chamber environment while maintaining the ability to measure pressure through the membrane interface.
Solution Approach 2:
The membrane serves as an intermediary that transmits pressure information from the high-temperature combustion chamber to the force sensor located in a cooler, protected region. This allows the sensor to measure pressure without being directly exposed to the harsh thermal environment.
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 design enhances pressure measurement reliability and sensitivity, efficiently evacuates heat from the combustion chamber, and reduces the impact of finger vibrations on sensor accuracy, while maintaining compatibility with standard metal heater fingers.
Implementation Method 1
It is known to incorporate a force sensor, usually a piezoelectric sensor, in such a heater plug
Implementation Method 2
a heating electrode seated in the finger... enables the combustion chamber of said cylinder to be heated
Data Source
AI summary
This heater plug includes:A tubular body (2),A finger (4) mounted inside the tubular body (2) and protruding outside the body at one extremity of this body, andA pressure sensor (8),A membrane (28) extending between the body (2) and the finger (4) enabling a relative longitudinal movement between the finger (4) and the body (2). The pressure sensor (8) is arranged between firstly a first bearing part (38) connected via a first tubular part (20, 20′) to the finger (4) in the vicinity of the membrane (28) and a second bearing part (40) connected via a second tubular part (22) to the body (2).