RU2293294C2 - Elastic member of device for measurement of radial pressure - Google Patents

Abstract

FIELD: mechanical engineering; measuring technique.

SUBSTANCE: device can be used for measurement of forces created by pressure of elastic items, for example, of piston rings against wall of cylinder. There are slots along generating lines of body of rotation in elastic member. Slots have minimal widths and links with transistors, which increase number of links separating them. Slots are made in edge of part of body of rotation; links have to be cantilever beams. Slots are made in edge part of variable cross-section body of rotation and links have to be L-shaped cantilever beams. Projections of radial pressures are reproduced with higher truth. Radial pressure can be measured which pressures are created by piston ring against surface of cylinder.

EFFECT: improved precision of measurement; improved truth of results; higher wear resistance; prolonged service life of elastic members.

2 cl, 5 dwg

Description

The invention relates to mechanical engineering and can be used in measuring technique for measuring the forces created by the pressure of elastic parts, for example piston rings, on the cylinder wall.

A known design of a device for determining the distribution of radial pressures generated by a piston ring on a cylinder surface, which is made in the form of an H-shaped body of revolution in axial section, with a flange at the base of the casing, covering the body of rotation so that an annular chamber and covers are formed between the surfaces, and as measuring elements we used tensometric beams installed in the chamber, each of them in contact with the pin and with the adjusting screw, the measured ring at the outer surface The surface is supported by pins, and they transfer forces to tensometric beams, which are the measuring elements of the device, which are separate elements independent from each other (see USSR patent No. 323924 of 09.25.69).

The disadvantage of this design is the design complexity, which requires significant setup time for measurement, as well as the lack of reliability of reproducing the pressure plot due to the limited number of measuring elements.

The closest design for the same purpose to the claimed invention in terms of features is an elastic element of a tensometric epurometer made in the form of a hollow body of revolution of cylindrical shape, the inner diameter of which is equal to the diameter of the cylinder, with rectangular windows located along the body of revolution and with jumpers separating them, the width there are more windows than the width of the jumpers, and the jumpers are beams of equal cross-section along the entire length with strain gauges glued to them, while zhdaya Ravine is a measuring element (see. avt.svid. USSR №171636 from 2.12.63 g).

The disadvantage of this design is the lack of accuracy in measuring and reproducing the diagram of radial pressures due to the mismatch of the conditions of support of the piston ring placed in the measuring device and in the engine cylinder, as well as the limited number of measuring elements, insufficient wear resistance and durability of the elastic element.

The essence of the invention lies in the development of the design of the elastic element, in which the implementation of the slots of the minimum width allows, on the one hand, to approximate the conditions of abutment of the piston ring placed in the measuring device to the conditions of abutment of the ring in the ICE cylinder by eliminating the bending deformation of the ring between the jumpers, and on the other hand, increase the number of measurement points with measuring elements - strain gauges that are on the jumpers between the slots. This allows you to significantly improve the accuracy of measurement and the reliability of the reproduction of the plot of radial pressures created by the piston ring on the surface of the cylinder, and also leads to increased wear resistance and durability of the elastic element by reducing the forces acting on the jumpers.

EFFECT: increased accuracy of measurement and reliability of reproducing a diagram of radial pressures, as well as increased wear resistance and durability of an elastic element of a device for measuring radial pressures created by a piston ring on a cylinder surface.

The specified technical result is achieved by the fact that in the elastic element of the device for measuring radial pressures generated by the piston ring on the surface of the cylinder, made in the form of a hollow body of revolution of cylindrical shape, the inner diameter of which is equal to the diameter of the cylinder, with windows located along the windows forming the body of revolution and separating them jumpers, with strain gauges fixed to them, the windows are made in the form of slots of the minimum width, which eliminates the bending deformation of the piston ring between the to increase the number of separating jumpers with measuring elements, as well as reduce the radial forces acting on the jumpers when installing the ring, in addition, the slots are made in the end part of the body of revolution, and the jumpers are cantilever beams, in addition, the slots are made in the end part of the body rotations of variable cross section, and jumpers are cantilever beams of an L-shape.

The drawings show: in Fig.1 shows an elastic element with slots made in the end part of the body of revolution with jumpers in the form of cantilever beams; figure 2 is a section aa in figure 1; figure 3 shows the elastic element with slots made in the end part of the body of revolution of variable cross-section, with jumpers in the form of cantilever beams L-shaped; figure 4 is a cross-section bb in figure 3; 5 is an example of constructing a plot of radial pressures generated by a piston ring on the cylinder walls, obtained using a device with the proposed elastic element.

The elastic element of the device for measuring radial pressures generated by the piston ring 5 on the surface of the cylinder is made in the form of a hollow body of revolution of cylindrical shape 1, the inner diameter of which is equal to the diameter of the cylinder, with slots 2 arranged along the generatrix of the body of revolution and having a minimum width, with jumpers 3 s mounted on them by strain gauges 4, and the slots 2 (Fig. 1) are made in the end part of the body of revolution 1, and the jumpers 3 are cantilever beams, and the slots 2 (Fig. 3) are made in the end h The parts of the rotation body are of variable section 1, and the jumpers 3 are cantilever beams of an L-shape with strain gauges 4 fixed to them.

To measure the diagram of the radial pressures of the piston rings on the cylinder surface with sufficient accuracy, the following conditions must be met: the ring must be supported by the maximum possible number of measuring elements when measuring, the latter must be located at a diameter equal to the diameter of the ICE cylinder, and the bearing surface should have minimal deviations from roundness; elastic measuring elements should have maximum stiffness, i.e. minimal "subsidence" under load. If these conditions are not met, a significant redistribution of pressures occurs around the perimeter of the ring, which distorts the real diagram of radial pressures. The accuracy of measuring the points of the diagram of radial pressures is directly proportional to the value of the output signal of the strain gauge (proportional to the relative deformation or the actual stress) and inversely proportional to the magnitude of the deflection of the elastic element. The measurement accuracy at each point can be estimated using the sensitivity coefficient of the measuring channel:

, где

where

κ is the sensitivity coefficient;

σ is the voltage at the installation site of the strain gauge on the measuring element;

f is the deflection of the measuring element at the installation site of the piston ring; for cantilever beams, the stresses in the embedment area and deflection at the installation site of the piston ring are calculated using the following formulas:

, где

where

P is the pressure force of the piston ring on the measuring element;

L is the length of the beam (measuring element);

W is the moment of resistance of the beam;

E is the modulus of elasticity of the material of the beam;

J is the moment of inertia of the beam section.

Thus, the measurement accuracy at each point of the pressure plot does not depend on the magnitude of the force on the elastic element, but depends only on the length of the elastic element L, its geometrical characteristics of the cross section J, W and the elastic properties of the material E. In addition, the measurement accuracy on each measuring element directly proportional to the number of installed strain gages operating in the active arms of the electric strain gauge bridge.

For the manufacture of slots on an elastic element made in the form of a hollow body of revolution of a cylindrical shape, an EDM wire-cutting machine is used, which allows to make slits of a minimum width of 0.1 mm, depending on the diameter of the wire used, and the slots are made in one pass. The operation of making slots is carried out as final, after heat treatment, grinding and honing of the workpiece. Since the processing is carried out in a coolant medium, the cutting forces do not act on the jumpers, as during milling or grinding, and, in addition, there is no temperature effect, which makes it possible to obtain an elastic element with high accuracy of geometric dimensions and stable shape characteristics, and also increased wear resistance and durability required when measuring radial pressures of piston rings.

The work of the elastic element for measuring radial pressure of piston rings on the surface of the cylinder is as follows. To determine the radial pressure diagram, the measured piston ring 5 is installed in the elastic element 1 with slots 2 until it stops. Due to the elastic forces, the piston ring 5 deforms the jumpers 3 with strain gauges 4 fixed to them, each jumper 3 being a part of the measuring channel. Electrical signals from the sensors of each measuring channel are recorded and recorded by the measuring device, after which the radial pressure diagram created by the piston ring on the cylinder surface is constructed from the obtained values. An example of constructing a plot of radial pressures obtained by measuring the piston ring is shown in Fig.5. Before taking measurements, each measuring channel is calibrated with static loads using a calibration device.

An advantage of the invention is that, compared with the known elastic elements, the claimed elastic element of the device for measuring radial pressures generated by the piston ring on the cylinder surface allows to increase the accuracy of measuring and reproducing the plot of the radial pressures of the piston rings on the cylinder wall by eliminating the bending deformation of the piston ring between jumpers and increasing the number of jumpers with strain gauges, which are measuring elements, and also increase wear resistance l and the durability of the elastic element.

Claims (2)

1. An elastic element of a device for measuring radial pressure, containing a hollow body of revolution of cylindrical shape, the inner diameter of which is equal to the diameter of the cylinder, with windows located along the generatrix of the body of revolution and with jumpers separating them, with strain gauges fixed to them, characterized in that the windows are made in in the form of slots of minimum width, increasing the number of bridges separating them, and the slots are made in the end part of the body of revolution, and the bridges are cantilever beams. 2. The elastic element according to claim 1, characterized in that the slots are made in the end part of the body of revolution of variable cross section, and the jumpers are cantilever beams of an L-shape.

Images