Mass Flow Sensor Vibration Decoupling via Spiral Spring Bearings
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Solution Overview
Problem
Existing mass flow sensors with single oscillatable measuring pipelines face challenges in avoiding environmental interference, particularly in accelerated reference systems like bottling plants, due to difficulties in decoupling useful bending vibrations from disturbing vibrations, which affects calibration factors.
Innovation Solution
A compact mass flow sensor design featuring a single oscillatable measuring pipeline with a two-fold rotational symmetry, supported by a carrier plate with spiral spring bearings, allowing for decoupling of vibrations and minimizing the influence of rotations on the calibration factor through strategic positioning of vibration sensors and bearing bodies, ensuring frequency separation and minimal disturbance to the useful bending vibration mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single oscillating measuring pipe is used, then the sensor is more compact and does not contain flow dividers, but it is more difficult to prevent interaction with the environment by coupling out vibrational energy
Solution Approach 1:
The support plate is designed with specific vibration modes and natural frequencies before the measuring pipe operates, creating a frequency separation that prevents environmental vibrations from coupling into the measuring pipe. This preliminary design of the support structure's vibrational characteristics blocks harmful environmental interactions before they can affect the measurement.
2Device complexity
If the measuring pipe has twofold rotational symmetry, then the design is simplified and compact, but rotational dependence of the calibration factor increases
Solution Approach 1:
The vibration sensors are positioned at specific locations on the measuring pipe where the rotational dependence of the calibration factor is minimized. By carefully selecting the local positions of the sensors rather than changing the overall pipe symmetry, the design maintains its simplicity while achieving stable calibration factors that are insensitive to rotational orientation.
3Strength
If the support plate has high natural frequencies, then it is stiffer and more stable, but it couples out less vibrational energy and increases interaction with the environment
Solution Approach 1:
The natural frequencies of the support plate are specifically designed to be lower than the useful mode natural frequency of the measuring pipe. By changing the frequency parameter of the support structure rather than its stiffness, the system allows the support plate to be less stiff while creating a frequency separation that prevents environmental vibrations from coupling into the measuring pipe.
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 results in a sensor that is immune to interference, maintaining measurement sensitivity and robustness even in accelerated environments, with a compact design that ensures effective decoupling of vibrations and minimal impact on calibration factors.
Implementation Method 1
The support plate has, in particular, spiral-shaped spring bearings, wherein each spring bearing is exposed by at least one cut in the support plate, wherein the support plate is resiliently mounted relative to the sensor housing via the spring bearing(s)
Implementation Method 2
at least one vibration exciter for exciting bending vibrations of the measuring pipe in a bending vibration mode
Implementation Method 3
at least two vibration sensors for detecting vibrations of the measuring pipe
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The invention relates to a mass flow rate sensor (100) comprising a vibratable measuring pipeline bent in a pipeline plane, a vibration exciter (53) for exciting bending vibrations in a bending vibration operating mode, and two vibration sensors (51, 52) for detecting vibrations, a support system having a carrier plate (30) and an in-flow-side and an out-flow-side bearing element, and a sensor housing, wherein the support system has support system vibrating modes including elastic deformations of the carrier plate, wherein the measuring pipeline (10) is securely connected to the carrier plate (30) by means of the in-flow-side bearing element (20, 21) and by means of the out-flow-side bearing element, and same is limited by the bearing elements (21, 22), wherein the carrier plate has a number of spring bearings (31, 32, 33, 34) released by cuts in the carrier plate, via which the carrier plate is mounted on the sensor housing (40) with vibrational degrees of freedom, the natural frequencies of which are lower than an operating mode natural frequency of the bending vibration operating mode, wherein the operating mode natural frequency is lower than the natural frequency of the support system vibration modes, wherein, in the first estimation, a calibration factor (Calf) describes a proportion between a mass flow rate through the measuring pipeline and a phase difference between vibrations of the measuring pipeline vibrating in the bending vibration operating mode at the site of the two vibration sensors, wherein the vibration sensors are positioned such that, when rotating the sensor about an axis of rotation running perpendicular to the axis of symmetry of the two-fold rotational symmetry and perpendicular to a longitudinal axis of the sensor, a rotational speed dependence of the calibration factor (Calf) has a minimum, or exceeds the value of the minimum by no more than 20%, in particular by no more than 10%, and preferably by no more than 5% of said value.