Method and sensor for measuring a mass flow
First Claim
1. Method for measuring the mass flow of a gas or a liquid, comprising the steps ofleading the gas or the liquid over a first temperature sensor that produces a first temperature signal, a heating element and a second temperature sensor that produces a second temperature signal, operating the heating element in cycles for saving heating energy, wherein in a first cycle phase the heating element is operated at higher temperature than in a second cycle phase, wherein the first cycle phase is shorter than the second cycle phase, and determining the mass flow from the respective first and second temperature signals of the two temperature sensors.
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Abstract
A heating element (4) is arranged between two temperature sensors (5, 6) in order to measure the mass flow of a liquid or a gas. The mass flow is determined from the temperature difference of the temperature sensors (5, 6). The heating element (4) is operated by pulses in order to reduce power consumption of the device. A further reduction of the power consumption is reached by means of a monitoring circuit (12), which switches the actual measuring section (11) on only if the signals from the temperature sensors (5, 6) fulfil a threshold condition.
43 Citations
17 Claims
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1. Method for measuring the mass flow of a gas or a liquid, comprising the steps of
leading the gas or the liquid over a first temperature sensor that produces a first temperature signal, a heating element and a second temperature sensor that produces a second temperature signal, operating the heating element in cycles for saving heating energy, wherein in a first cycle phase the heating element is operated at higher temperature than in a second cycle phase, wherein the first cycle phase is shorter than the second cycle phase, and determining the mass flow from the respective first and second temperature signals of the two temperature sensors.
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7. Mass flow sensor for determining the mass flow of a gas or a fluid comprising
two temperature sensors arranged in a flow direction one after the other and producing respective first and second temperature signals, a heating element arranged between the temperature sensors and measuring means for determining the mass flow from the respective first and second temperature signals of both temperature sensors and comprising a pulse control for feeding energy in pulses to the heating element for generating heating pulses, wherein a distance of consecutive pulses is longer than the pulses themselves.
Specification