SU1226054A1 - Pneumatic device for measuring linear dimensions - Google Patents

Abstract

The invention relates to pneumatic measurements of linear dimensions and allows improving the accuracy of measuring linear dimensions with the help of two measuring branches and a counterpressure branch. In the measuring branches, identical input chokes are installed, and the output chokes are made in the form of laminar channels in the measuring equipment with the same static and different dynamic flow characteristics. When measured using a comparison membrane element, the pressure difference in the inter-throttle chambers of the measuring branches is determined, and a signal is generated from this difference, which on the other comparison element is added to the pressure difference in the inter-throttle chambers of one of the measuring branches and the counterpressure branch. 1 IL-. JI tvo you ate

Description

The invention relates to a measurement technique and can be used to measure linear dimensions in mechanical engineering.

The purpose of the invention is to increase the measurement accuracy by additional unbalance of the device when the controlled size deviates from the nominal size using two measuring branches with the same static and different dynamic discharge characteristics.

The drawing shows a schematic diagram of the proposed device.

The pneumatic device for measuring linear dimensions communicates with the compressed gas source (not shown) the first measuring branch with the inlet throttle 1 and the laminar throttle 3 installed in measuring equipment 2, the second measuring branch with the inlet throttle 4 and installed in the equipment 2 laminar throttle 5 and a backpressure branch with an unregulated throttle 6 at the inlet and an adjustable throttle 7 at the outlet, as well as two membrane elements 8 and 9 of the comparison.

The first comparison element 8 is communicated via an input 10 with an inter-throttle chamber 11 of the counterpressure branch,. through input 12 with the inter-throttling chamber 13 of the first measuring branch and through input 14 with the output 15 of the second comparison element 9. The second element 9 of the comparison is communicated via the input 16 to the inter-throttling chamber 17 of the second measuring branch, and through in-18 to the inter-throttling chamber 13 of the first measuring branch. The output 1 of the first base element 8 is the output of the device.

Throttles 1 and 4 are identical. Laminar chokes 3 and 5 have the same static and significantly different dynamic flow characteristics. Chambers 13 and 17 are of the same volume.

The measuring equipment 2 is mounted on the supervised part 20.

When the part 20 is missing, both measuring branches have the same statutory flow characteristics, the pressures in chambers 13 and 17 are equal.

With the installation of the part 20, the size of which is less than allowable, a relatively large gap S occurs, which leads to some imbalance of the measuring branches, but does not contribute to a significant restructuring of the flow in laminar throttles x 3 and 5, therefore their dynamic resistances slightly differ

from each other and the differential pressure in the intercranial chambers 13 and 17, as well as in the respective chambers of the comparison membrane element 9, does not change significantly. In this case

output pressure R.

Out

definitely

depends on these signals, and the device operates as a conventional differential linear dimension meter, moreover, the rate of change of pressure at the output of the device Pgyj indicates that the part size is less than permissible.

With a small gap S, i.e. when the size of the part 20 is greater than the allowable, in the laminar throttles, the flow velocity fields are rearranged so that, for example, the dynamic resistance of the laminar throttle 5 becomes greater than the dynamic resistance of the laminar throttle 3, and the pressure in the inter-throttle chamber 17 grows faster. The resulting pressure drop in chambers 17 and 13 acts on the membranes of the reference element 9, at the output of which and in the chambers of the comparison element 8 the pressure quickly rises. Accordingly, the rate of increase in the output pressure Pj, y is significantly greater than in the first case, which indicates that the size of the part is larger than the allowable one.

The use of the proposed pneumatic contactless device for measuring linear dimensions improves measurement accuracy by introducing an additional measuring branch and pressure imbalance in the inter-throttle chambers of the measuring branches, which affects the output pressure.

Claims (1)

Invention Formula A pneumatic device for measuring linear dimensions, comprising a measuring branch communicated with a source of compressed gas with an inlet choke and a laminar outlet choke and a counterpressure leg with two throttles, the first membrane element of comparison, the two inputs of which are connected with interstitial chambers of the measuring and counterpressure branches, and the second membrane element of the comparison, characterized in that, in order to improve the measurement accuracy, it is equipped with a second measuring branch with an inlet throttle identical to the input throttle the first measuring branch. and a laminar choke at the outlet, two inputs of the second membrane element of the comparison are communicated with interstitial chambers of the first and second measurement branches, the output of the second membrane element of the comparison is communicated with the third input of the first membrane element of the comparison, and laminar chokes are made with the same static and different dynamic flow characteristics. / L / A nineteen Compiled by V. Gordeev Editor O. Yurkovetska Tehred N. Boikalo Proofreader L. Pilipenko Order 2110/28 Draw 670 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and Printing Enterprise, Uzhgorod, st. Design, 4.