RU2279042C1 - Manometric spring with increasing characteristics - Google Patents

Abstract

FIELD: instrument industry.

SUBSTANCE: manometric spring is defined by the sealed connection of two bar-like thin members provided with the longitudinal corrugations. The cross-section of the spring is determined from the ratio A/B > 1, where A is the large axis of the cross-section and B is the small axis of the cross-section of the spring. For each corrugation 2H/d > 1, where d and H are the width and height of the corrugation, respectively.

EFFECT: expanded functional capabilities.

1 cl, 3 dwg

Description

The invention relates to elastic sensors used in gauge devices, for example in gauges, thermometers, vacuum gauges, level gauges, flow meters.

Currently, various designs of gauge springs are known. Known gauge springs, the cross section of which may have a plane oval, elliptical or figure-eight shape / 1 /. Known design manometric springs with asymmetric cross-section, on the outer and inner contours of which are one or more longitudinal ridges / 2 /. Known gauge spring, in which on the external and internal contours of the cross section are one or more longitudinal corrugations, the shape and dimensions of which vary from the fixed end of the spring to the free / 3 /.

A common drawback of the known designs of gauge springs is the non-linearity of their elastic characteristics, which reduces the accuracy of all gauge instruments using a gauge spring as a sensing element. Another disadvantage of the known designs of gauge springs is the impossibility of selecting the required nonlinear elastic characteristics of the gauge springs, which is often necessary for measuring physical quantities non-linearly related to pressure. Values nonlinearly related to pressure can be measured using instruments that use a membrane or bellows as an elastic sensing element, but the drawback of such instruments is a rather complex and cumbersome design. Also, devices that use a membrane or a bellows as an elastic sensitive element develop sufficiently high traction forces, which in some cases, for example, when measured by a force compensation scheme, is undesirable.

The objective of the invention is to obtain a gauge spring with a given increasing or linear elastic characteristic.

The technical result of the invention is to reduce the stiffness of the gauge spring with increasing pressure.

The technical result of the invention is achieved in that the gauge spring is formed by a hermetic connection of two strip-shaped parts of small thickness, forming the external and internal contours of the cross section, while for the cross section the condition A / B> 1 is fulfilled, where A is the major axis of the cross section of the spring, B - small axis of the cross section of the spring. Striped parts of small thickness have longitudinal corrugations, while for each corrugation the condition 2H / d> 1 is fulfilled, where d, H are the width and height of the corrugation under consideration, respectively. The technical result of the invention can also be achieved in the case when the corrugations made on strip-like parts have variable pitch and (or) height along the midline of the corrugations.

The proposed design of the gauge spring is quite technologically advanced, since the manufacture of the gauge spring can be carried out in three stages:

- obtaining thin-sheet strip-shaped corrugated parts of the desired shape and with the necessary shape of the corrugations (for example, stamping);

- bending the obtained strip-like parts on the rolling rollers with the corresponding corrugation profile along an arc of a given radius;

- welding or soldering the obtained corrugated strip-like parts into a single, airtight design.

Between the technical result of the invention and its essential features, there is the following causal relationship.

The elastic characteristic of a gauge spring is the dependence of the movement of the end of the gauge spring upon a change in pressure. If with increasing pressure the end of the spring receives more and more displacements, the elastic characteristic is increasing, otherwise the manometric spring has a damping characteristic. The displacements of the end of the gauge spring depend on the deformation of the external and internal contours of the cross section, namely, the displacement of each point of the cross section profile from the major axis of the cross section.

For the claimed design of the gauge spring with increasing pressure in the inner cavity of the spring, its cross section receives the following deformations. The presence of corrugations on the external and internal contours of the spring’s cross section and the fulfillment of the condition 2H / d> 1, where d, H are the width and height of the corrugations, respectively, lead to the fact that, first of all, the large axis of the spring’s cross section increases significantly - in the cross section the manometer spring works like a bellows - the corrugations are stretched. Along with this deformation, the distance from the central axis of the gauge spring to all points of the external and internal contours of the cross section changes, due to which the free end of the spring gets displaced. As a result of the increase in the major axis of the cross section (stretching of the corrugations), the stiffness of the gauge spring decreases with increasing pressure, and the points of the external and internal contours of the cross section receive ever greater displacements, which leads to an increase in the increments of displacement of the free end of the gauge spring with increasing pressure. As a result of such a deformation, the elastic characteristic of the gauge spring is increasing. Given that the elastic characteristic of known designs of gauge springs is damped / 4 /, changing the geometric parameters of the cross section of the gauge spring, the height, width and pitch of the corrugations can achieve a linear, elastic characteristic.

Extending the range of non-linearity of increasing elastic characteristics or obtaining the desired angle of inclination of the linear elastic characteristics can be achieved by corrugating, with variable pitch and / or height of the corrugations, along the midline of the corrugations.

Figure 1 presents a General view of a gauge spring.

Figure 2 shows a cross section of a gauge spring.

Figure 3 shows the geometric parameters of the longitudinal corrugations made on the external and internal contours of the cross section of the spring.

The gauge spring 1 has a free end 2, an end 3 fixed in the holder 4, a longitudinal axis 5, a central axis 6 and an internal cavity 7.

The longitudinal axis 5 is located at a distance R from the central axis 6 and lies in a plane perpendicular to the central axis 6.

Gauge spring 1 is formed by a hermetic connection of two strip-shaped parts 8 and 9, respectively, forming the outer 10 and inner 11 contours of the cross section of the spring.

The dimensions of the cross section are determined by the value of the small axis of section B and the large axis of section A, while the condition - A / B> 1 is fulfilled for the cross section of the spring.

The strip-like parts 8 and 9 have longitudinal corrugations 12 (along the longitudinal axis 5).

On the outer 10 and inner 11 contours of the cross section of the spring, one can distinguish the middle line of the corrugations 13 — a line in the cross section equally spaced from the tops and troughs of the corrugations 12. The geometric parameters of the corrugations 12 are the width of the corrugation d, the height of the corrugation N and the corrugation pitch 1, while for of each corrugation, the condition 2H / d> 1 is fulfilled, where d, H are the width and height of the corrugation in question, respectively. The corrugations 12 can be made with variable pitch and (or) height along the midline of the corrugations 13.

Gauge spring 1 operates as follows. When overpressure is created in the inner cavity 7, the corrugations 12 located on the outer 10 and inner 11 cross-sectional circuits are stretched - the large axis A of the cross-section increases, and the stiffness of the gauge spring decreases. At the same time, the distance from the central axis 6 to the points of the outer 10 of the cross-sectional contour increases, and the distance from the central axis 6 to the points of the inner 10 of the cross-section contour decreases. With increasing pressure, the stiffness of the spring becomes less and less, and the points of the external 10 and internal 11 contours of the spring’s cross-section receive more and more displacements, which leads to an increase in the increments of displacement of the free end 2 of the spring 1 and causes an increase in the elastic characteristic of the gauge spring 1. Changing the geometric parameters of the corrugations, one can obtain not only an increasing elastic characteristic, but also strictly linear.

Information sources

1. Andreeva L.E. Elastic elements of devices. - 2nd ed., Revised. and add. - M., Mechanical Engineering, 1981, 392 p.

2. A.S. 403977 USSR, class G 01 L 7/04, publ. 10.26.73, Bulletin No. 43.

3. RU 2216001, cl. G 01 L 7/04, publ. November 10, 2003, Bulletin No. 31.

4. Tyzhnov G.I. Deformations and stresses in tubular manometric springs. The dissertation for the degree of candidate of technical sciences. Tomsk, 1964, 185 p.

Claims (2)

1. A manometric spring formed by the hermetic connection of two strip-shaped parts forming the external and internal contours of the cross section, characterized in that the strip-like parts have longitudinal corrugations, while the condition for the spring cross section is fulfilled A / B> 1, where A is the major axis of the cross section of the spring; In - the small axis of the cross section of the spring, for each corrugation the condition 2H / d> 1, where d, H are the width and height of the corrugation in question, respectively. 2. Gauge spring according to claim 1, characterized in that the corrugations made on strip-like parts forming the external and internal contours of the cross section of the spring have variable pitch and (or) height along the midline of the corrugations.

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