Mold Cavity Pressure Sensor Using Liquid-Isolated Flexible Membrane
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Solution Overview
Problem
Existing measuring devices for detecting pressure in a mold cavity during the foaming process are complex, require significant space, and suffer from friction-induced inaccuracies and temperature interference with pressure sensors.
Innovation Solution
A measuring device with a flexible membrane deflecting into a liquid-filled space, connected to a pressure sensor via a channel, and incorporating a mold temperature sensor for accurate pressure measurement without temperature interference, using a dual-function measuring head that also monitors mold and foam temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a movable pressure plate with tappet and volume booster is used, then pressure measurement is enabled, but device complexity increases and measurement precision deteriorates due to friction losses
Solution Approach 1:
The invention extracts the pressure sensor from the high-temperature mold cavity environment and places it in a separate, temperature-controlled location. The flexible membrane and liquid transmission medium are used to transmit pressure information without requiring direct contact between the sensor and the hot cavity, thereby eliminating temperature-induced measurement errors and reducing structural complexity.
Solution Approach 2:
The invention introduces a flexible membrane and liquid-filled chamber as intermediaries between the pressure source (mold cavity) and the pressure sensor. The flexible membrane deflects in response to pressure changes, transmitting this information through the liquid to the sensor located in a separate chamber, thereby eliminating direct thermal contact while maintaining accurate pressure measurement.
2Device complexity
If the pressure sensor is arranged close to the mold cavity, then pressure measurement is simplified, but measurement precision deteriorates due to high temperature interference
Solution Approach 1:
The invention segments the measurement system into distinct functional zones: a first chamber containing the flexible membrane and liquid-filled space positioned adjacent to the mold cavity for pressure reception, and a second chamber containing the pressure sensor positioned away from the cavity for accurate measurement. This spatial segmentation allows the sensor to be isolated from high-temperature interference while maintaining pressure measurement capability through the flexible membrane and liquid transmission medium.
3Measurement precision
If a flexible membrane with liquid-filled space is used, then measurement precision improves by eliminating friction losses, but device complexity increases
Solution Approach 1:
The invention replaces complex mechanical transmission systems (such as tappets and volume boosters with friction-prone guides) with a flexible membrane and liquid-filled chamber system. The flexible membrane deflects smoothly in response to pressure changes, transmitting information through the liquid without mechanical friction, thereby eliminating friction-induced measurement errors while reducing structural complexity compared to traditional mechanical linkages.
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 provides accurate, loss-free pressure measurement with reduced space requirements and enhanced temperature monitoring, ensuring precise control of the foaming process.
Implementation Method 1
a flexible membrane (9) which can be acted upon and deflected by the pressure in the cavity on its side facing the cavity... into a liquid-filled liquid space formed in the measuring head
Implementation Method 2
the recorded pressure can be supplied to a pressure sensor and can be converted by the pressure sensor into a corresponding electrical pressure signal
Implementation Method 3
a mold temperature sensor (14) which is arranged in an edge region of the measuring head close to a wall (18) of the mold and from which a second signal line leads to the transmitter head and with the mold temperature sensor being connected to a wall (18) of the mold in physical contact
Data Source
Figure 1~2
AI summary
The invention relates to a measuring device for detecting the pressure in a cavity 2 of a mold 1 of a particle foaming tool during a foaming process of particle foams. The device comprises a measuring head 4 arranged in a wall 18 of the mold 1, in which a pressure receiving device is arranged that can be acted upon by the internal pressure in the cavity 2, through which the detected pressure can be supplied to a pressure sensor and converted by the pressure sensor into a corresponding electrical pressure signal.The measuring head 4 has a movable piston which, on its side facing the cavity 2 and extending transversely to its piston plane, can be subjected to the pressure in the cavity 2 and can be deflected into a liquid-filled liquid chamber 8 formed in the measuring head 4 on its side facing away from the cavity 2, from which a channel 10 leads to a transmitter head 6 spaced apart from the particle foaming tool, in which the pressure sensor is arranged and can be subjected to the liquid.