Pressure measurement#Bourdon
The Bourdon tube (also Bourdon, Bourdon tube ) is a measuring element for measuring pressure differences. It comes in the most mechanical pressure gauges are used. Bourdon tubes are also used in pressure switches and temperature measurement in gas thermometers and thermostats. The Bourdon tube is usually a geplättetes, circular, snails or helically coiled metal tube; this form of the Bourdon tube is named after their Erstpatentierer also Bourdon tube. Since this is the most commonly used form of the Bourdon tube, the Bourdon tube concept is often used synonymously with Bourdon tube.
When pressure is applied the spring strives to aufzubiegen itself. The change in displacement of the spring end is transmitted via a drawbar to a measuring unit and translated into a rotation of the pointer spindle. The effect, which is utilized here can be most easily illustrated by an blowouts whistle.
History
The principle of the pressure measurement tube by spring 1845 of a railroad engineer named Rudolf Schinz Eduard discovered by accident when he tried to judge deformed by pressure pipes. Then he constructed a gauge for locomotives, which was based on a helically wound Bourdon tube with elliptical cross section. 1848 Schinz tried to patent his design in Prussia.
1848 patented the Paris instrument maker Eugène Bourdon, the measuring principle, which, under his name is known even today, especially in the Anglo-Saxon and French -speaking countries. In 1859 the patent U.S. Pat No. 9163 of August 3, 1852 (ET ) has been successfully challenged by Lucien Vidie, the inventor of the aneroid capsule and crushed with the help of his friend and patent lawyer Pierre Armand Lecomte.
Application and versions
Down tube springs are distinguished train and compression springs, torsion springs and torsion springs. Under the train and compression springs falls among others the metal bellows. Here, the linear expansion of a thin walled, closed on one side and on the other side is acted upon with pressure the corrugated pipe is transferred to a measuring equipment. Torsional or twisting tube springs are just to oval or star- shaped cross-section pressed and twisted in itself pipes that handle themselves under pressure. The rotary motion is transmitted to a pointer shaft. While these two versions technically play only a minor role, the curved cantilever springs ( Bourdonfedern ) are produced in large quantities and used in pressure gauges, gas pressure thermometers and switching devices. Bourdonfedern be according to their type of winding in circular springs ( ~ 0.6 ... 60 bar), snails springs ( ~ 60 .. 1000 bar ) and coil springs divided (up to ~ 4000 bar). The further adaptation to different measuring ranges is done by varying the tube wall thickness of the pipe cross-sectional geometry and the Bourdon tube material.
Bourdon tubes are usually made of metallic materials. Since the measuring medium penetrates into the Bourdon tube, the material used must be compared with the measured medium or a liquid-filled diaphragm seal be used constantly. Most are brass, copper or copper-nickel alloys and stainless steel or mild steel. For the measurement in the vacuum range up to about 10-6 bar special pipe springs made of quartz glass.
All types of pipe springs must be designed so that they do not get in normal operation in the field of plastic deformation. If a pressure gauge so overloaded, the pointer will not move when pressure is released to the scale zero.