CN2223489Y

CN2223489Y - Improved diaphragm stretching clamp

Info

Publication number: CN2223489Y
Application number: CN 95213526
Authority: CN
Inventors: 王耀东
Original assignee: BEIJING FAR EAST INSTRUMENT Co Ltd
Current assignee: BEIJING FAR EAST INSTRUMENT Co Ltd
Priority date: 1995-06-21
Filing date: 1995-06-21
Publication date: 1996-03-27
Anticipated expiration: 2005-06-21

Abstract

The utility model provides an improved diaphragm stretching clamp, which is used for the stretching process of center diaphragm in a capacitance type pressure difference pressure transmitter. The utility model is primarily redesigned the spline shape of upper and lower pressure rings, and along each direction of a circle the rate of tension is full symmetry during the course of stretching the center diaphragm. The utility model overcomes the defect of non-uniform symmetry of stress in the existing clamp.

Description

Improved diaphragm tensioning jig

The present invention relates to a kind of diaphragm tensioning jig, measure the tensioning jig of sensitive element center diaphragm especially for the capacitance differential pressure cell of measuring fluid pressure.

At present, the capacitance differential pressure cell of domestic production is the production technology from external introduction.It adopts the capacitor type sensitive element of sealing fully, and direct sensing pressure to eliminate mechanical transfer, reduces the problem that shock and vibration bring.This principle of sensing element is: constitute an annular seal space (being called the δ chamber) by the rigid insulation body, as shown in Figure 1.The isolation diaphragm of pressure process (by measuring pressure) by one or both sides reaches center diaphragm in the δ chamber through filling liquid.The center diaphragm is the flexible member of a tensioning, and it produces corresponding modification displacement by the pressure at both sides difference that acts on it, and its displacement is directly proportional with pressure reduction, and maximum displacement is about 0.1mm.This displacement produces both sides, δ chamber changes in capacitance, by circuit differential capacitor is become the standard signal of two-wire system 4～20mA again.The center diaphragm of this shows be the most initial also be most important measurement sensitive element, its various performances all have direct influence to every technical indicator of transmitter.What the transmitter of middle lower range adopted is the stretched diaphragm measuring sensor, and the size of the internal stress homogeneity of its tensioning, rate of tension and the tensioning consistance of each sensor are very crucial for the pressure unit of capacitance principle.Now the tensioning jig that uses finds that in use the data of tensioning constantly drift about---the diaphragm that is tensioning is slowly fluffing.By analysis, problem results from the hold-down ring of tensioning jig.In order in the tensioning process, " to bite " marginal portion of diaphragm, the end face of the hold-down ring that the uses dextrorotation spiral of Archimedes (forming naturally) of having got on the bus now by engine lathe.Just problem occurred when two hold-down rings are lived center diaphragm edge clamping face-to-face: look up from a side, two aspectant archimedean spiral grooves become the first from left right side.As Fig. 2.Two helicals are (being that the flute profile peak is to the peak) that overlap near 0 ° and 180 ° of phase places like this.As shown in Figure 3.And near 90 ° and 270 ° of phase places, 180 ° of phase places that two archimedes lines are just poor (be flute profile peak to paddy, paddy is to the peak), as shown in Figure 4.Therefore, near 0 ° and 180 °, the center diaphragm is encircled peak tooth good " killing " up and down and can't be skidded.And near 90 ° and 270 °, owing to encircle the tooth peak to tooth paddy up and down, so the center diaphragm is pressed into corrugated, can not well clamp, and can slowly skid in the tensioning process, makes diaphragm produce different tensile stress in different directions.This phenomenon is sharper owing to profile of tooth when hold-down ring is new, so skidding is not obvious.And along with the wearing and tearing of hold-down ring profile of tooth, skidding is serious further.The operator can only reach same integrating capacitor reading by increasing tensioning pressure, and the unevenness that this has just aggravated tensile stress makes elastic hysteresis increase, and the sensor overload error of producing increases, and nonlinearity erron increases.

The objective of the invention is to make a kind of improved diaphragm tensioning jig, promptly at the problem of above-mentioned existence, groove on the hold-down ring is up and down redesigned, make the center diaphragm when the process of tensioning, symmetrical fully along rate of tension on all directions in garden, to overcome the defective of the existing inhomogeneous symmetry of jig tensile stress.

The present invention is achieved in that by hold-down ring up and down the center diaphragm edge is formed on the on all four centrosymmetric clamping tooth stamp line of garden week all directions, thereby realizes that the diaphragm that is tensioned has uniform internal stress.Use diaphragm stress accommodation provided by the present invention to produce sensor, its overload error and nonlinearity erron are stable always, far below the technical conditions required standard.

Below in conjunction with accompanying drawing and an embodiment the present invention is done more detailed description.

Accompanying drawing 1 δ cell structure synoptic diagram;

Signal when two of accompanying drawing 2 spiral of Archimedes are relative;

In accompanying drawing 3 original technology, when 0 ° and 180 ° of positions, encircle the signal of tooth peak up and down;

In accompanying drawing 4 original technology, when 90 ° and 270 ° of positions, encircle the signal of tooth peak up and down;

The tooth stamp line of accompanying drawing 5 improved diaphragm tensioning jigs;

Accompanying drawing 6 improved diaphragm tensioning jig upper press ring groove shapes;

Pressure ring groove shape under the accompanying drawing 7 improved diaphragm tensioning jigs.

In the accompanying drawing 1, (1) is the capacitor fixing pole plate, and (2) are the center diaphragms, and (3) are the rigid insulation bodies, (4) filling oil, and (5) seal weld T-Ring, (6) isolation diaphragm, (7) are that electric signal is drawn lead.

The embodiment that accompanying

drawing

5,6,7 provides is, the teeth groove of following pressure ring is a concentric ring, and (as shown in Figure 7), the teeth groove of upper press ring is eccentric radial straight-tooth flute profile, (as shown in Figure 6).The teeth groove of pressure ring composition promptly is that all directions evenly clamp tooth stamp line up and down, as shown in Figure 5.Because these tooth stamp lines evenly gather on the edge of diaphragm that is tensioned, and each clamping point do not overlap with the on line at diaphragm center, so eliminated the possibility that diaphragm skids in the tensioning process up hill and dale.Use through the several years, film head (sensor) the overvoltage precision of being produced remains on about 0.1% always, far below 0.5% of technical indicator regulation.

Claims

1 one kinds of improved diaphragm tensioning jigs mainly are made up of the hold-down ring up and down that has the teeth groove line, and the teeth groove line about it is characterized in that on the hold-down ring is that the center diaphragm edge is formed on all four centrosymmetric clamping tooth stamp line.

2 improved diaphragm tensioning jigs as claimed in claim 1 is characterized in that the clamping groove of hold-down ring up and down, and one is concentric ring shape teeth groove, and another is eccentric radial straight-tooth groove.