variable diameter orifice flowmeter

Abstract

The invention discloses a diameter-variable orifice-plate flowmeter which comprises throttling gears and a flow sensor, wherein a pipeline is arranged inside the throttling gear; a throttling hole is formed in the pipeline; the sectional area of the throttling hole is smaller than that of the pipeline; a movable membrane is arranged in the throttling hole; a gap is reserved between the membrane and the throttling hole; sampling probes are respectively arranged on the throttling gears on two sides of the throttling hole, and are communicated with the pipelines inside the throttling gears; and the sampling probes are connected with the flow sensor. The diameter-variable throttling hole is formed through adopting a movable membrane manner, so that the pipelines of different flows can be accurately measured, a gas flowmeter is guaranteed to have a sufficient measuring range, and the measuring accuracy is high; and the resistance of gas flow is not increased remarkably when the gas flow rate is higher, so that the breathing comfort level of a patient is ensured.

Description

technical field [0001] The invention relates to an orifice flowmeter, in particular to a variable diameter orifice flowmeter. Background technique [0002] In the rescue process of critically ill patients, mechanically assisted ventilation must be performed on patients, so ventilators, anesthesia machines, etc. are important rescue tools. During use, for patients, especially infants and critically ill patients, it is very important to control the size of the ventilation volume. Improper ventilation volume will bring danger to the patient, so the flow rate of the ventilation airflow must be accurately controlled. Measurement, while the resistance at the exhalation end directly affects the comfort of the patient. [0003] Among the gas flowmeters commonly used in existing ventilators and anesthesia machines, there is an orifice-type flowmeter, which consists of a throttling device, a sampling pipeline, and a differential pressure flow sensor. sender. The throttling device i...

AI Technical Summary

Problems solved by technology

However, in the medical clinical field, such as gas flow measurement of ventilators, anesthesia machines, etc., its technology is not mature

And this kind of flowmeter has obvious disadvantages: that is, if the orifice diameter of the throttling device in the flowmeter is small, the flow measurement range will be small, and it may also cause excessive exhalation resistance, which will affect the comfort of the patient and reduce the treatment efficiency. However, if the orifice diameter of the throttling device in the flowmeter is large, although it can meet the requirements of the measurement range, it cannot achieve accurate measurement because the pressure difference in the small flow range is too small.

[0005] Specifically, such as figure 1 As shown, curve A is the pressure difference-flow relationship curve when the orifice diameter of the throttling device of the flow meter in a ventilator is set to a small value. It can be seen from the figure that when the flow rate increases, the gas The passing resistance increases rapidly, and soon reaches the full scale of the differential pressure flow sensing device, which cannot meet the maximum flow measurement requirements of the ventilator, and also causes excessive expiratory resistance, affecting the therapeutic effect of the ventilator and patient comfort.

Curve C is the pressure difference-flow relationship curve when the orifice of the throttling device is set to a larger value. It can be seen from the figure that this curve meets the requirements of the flow measurement range, but the pressure difference change in the small flow range is too small , the differential pressure flow sensor device cannot accurately reflect the flow change, and cannot meet the precise measurement requirements for the flow

Therefore, in the prior art, throttling devices for flow meters cannot ensure accurate checking of flow

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