RU1795313C - Pressure pickup - Google Patents

Abstract

Usage: in instrumentation and can be used to register pressure pulses propagating in solids. SUMMARY OF THE INVENTION: The sensor comprises an elastic element in the form of a hollow cylinder with petals having spherical tips. Petals are evenly spaced around the circumference. By moving the rod with a truncated cone at the end through hemispherical protrusions, the movement of the petals is ensured. 3 s.p. f-ly, 3 ill.

Description

; The invention relates to a measuring and control technique, in particular, to devices for recording small pulsed pressures in solid bodies of finite dimensions, for example, inside metal parts of machines and mechanisms. It is especially effective to use the device when conducting research and development work when the direction of the intended propagation of a pressure pulse in space.

Known piezoelectric sensor PULSE pressures, containing elastic and power-transmitting elements, as well as pies with a damper,

A piezoelectric pulse pressure sensor is also known, which is the closest in technical essence to the proposed one and is taken as a prototype.

The known sensor comprises a transducer of displacement into an electric signal, a constricting and elastic element made in the form of a hollow cylinder, on

the first end of which is made a slot with the formation of petals, the free ends of which are provided on the outside with hemispherical collars.

The disadvantages of these known sensors are as follows.

To work with them, strictly spatial orientation is necessary so that the plane of the piezoelectric element is perpendicular to the direction of impact propagation. To find this direction, it is necessary to repeatedly rotate the sensor inside the hole, which lengthens the measurement cycle.

The known sensors are designed in such a way that the lobes of the elastic element are sufficiently rigid and a significant pressure pulse is required for their deformation. Low measurement accuracy and low sensitivity limit the use of sensors.

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The purpose of the invention is to improve the accuracy of measurements and the sensitivity of sensors.

Figure 1 shows a pressure transducer, axial section; in Fig.2 - view along arrow A. in Fig.1; in Fig.Z - section bB in Fig.1.

The pressure sensor contains an elastic element in the form of a hollow cylinder 1, on the first end of which three slots are made with the formation of six petals 2, evenly spaced around the circumference. The free ends of the petals 2 are provided with hemispherical collars 3 with a radius of gsf from the outside, and hemispherical protrusions 4 are made in the middle part of the inner surface of the petals 2.

The sensor also includes a displacement transducer 5 into an electric signal, a tightening nut b, a support washer 7, a guide 8 and a rod 9 with an axial hole. The rod 9 is placed in the cavity of the elastic element and is mounted coaxially with it with the possibility of movement along its axis. One end of the rod is threaded 10, and the other in the form of a truncated cone 11, the larger base of which is located at the end 12 of the rod. The guide 8 is secured with a nut 13 in the central part of the rod, and its conical surface 11 is in contact with the hemispherical protrusions 4. The support washer 7 is placed between the second end face of the elastic element and the tightening nut b fixed on the threaded surface 10 of the rod.

. The protrusions 4 are placed at a distance It equal to half the length fi of the petals 2;

. & fe

where f.i is the distance from the location of the shoulders 3 to the location of the protrusions 4 on the surface of the petals, and Јg is the length of the petals.

The outer cylindrical surface of the elastic element is made stepwise, while a step of a larger diameter DI is located at its second end, and a smaller D2 is on the side of the petals, and the ratio

Di / D2 1.05.

As a transducer 5 for moving into an electrical signal, a strain gauge is used, which is glued in the deformation zone to the inner surface of the petals 2 and connected to the display unit

which includes a multi-channel amplifier (not shown).

To install the sensor in the test body 14, a hole 15 is made in it. To fix the sensor 9 in the hole 15 of the sensor by rotation through the slot 16 of the rod 9 (when locked with a hexagonal nut 6), move the rod 9 in the axial direction, as a result of which it the conical surface 11 presses on the protrusions 4, which leads to the extension of the petals 2 until they contact the walls of the hole 15. After

fixing and creating a preliminary elastic deformation tension of the petals 2, fixed according to the indications of the display unit, stop the rotation of the rod 9. In this position, the petals 2 of the elastic element with the walls of the hole are gap-free. In this case, contact is made at six points.

The elastic element is made of an austenitic dispersion hardening alloy of 36NHTY grade or spring-spring steel of 65G grade. The surface extension for the sticker allows the use of wire or foil strain gauges.

The sensor operates as follows.

Pressure pulses propagate throughout the solid body 14, including at the location of the hole 15 and act on the cantilever elastic lobes 2

sensor. Due to the gapless coupling of the cylindrical surface 1 and the collars 3 of the sensor with the walls of the hole 15, and in its central part due to the contact of the protrusions 4 with the conical surface 11, a load of petals 2 is created, which is equivalent to the loading scheme of the beam on two supports with a centrally applied load. Such a loading circuit provides a high sensitivity of the sensor to

measured parameter.

The wide bandwidth of the used strain gages provides the perception of fast

elastic deformations at pulsed (shock) pressures.

The presence of six elastic lobes 2 in the sensor does not require additional rotations to search for an informative direction - the direction of propagation of pulses. Moreover, by the level of signals from all the strain gauges located on different petals 2, it is possible to measure the value with high accuracy and determine

direction of propagation of pressure pulses.

The sensor is simple in design, contains standardized elements.

Claims (4)

SUMMARY OF THE INVENTION 1. A pressure sensor comprising a transducer into an electrical signal, tightening a nut, and an elastic element made in the form of a hollow cylinder, at the first end of which a slot is made to form petals, the free ends of which are provided with hemispherical collars from the outside, about - on the one hand, and, in order to increase the accuracy and measurement due to the possibility of adjustment, it is equipped with a main washer, a guide and a rod with an axial hole placed in the cavity of the elastic element and mounted coaxially with it with the possibility of movement along its axis, with hemispherical protrusions made in the middle part of the inner surface of the grooves, one end of the rod being threaded and the other in the form of a truncated cone, the larger base of which is located on the end of the rod, while the guide is fixed in the central its parts, and its conical surface is in contact with hemispherical protrusions, the support washer being placed between the second end face of the elastic element and the tightening nut fixed to the threaded surface of the rod, 2. The sensor according to claim 1, characterized in that, in order to increase sensitivity, hemispherical protrusions are placed at a distance equal to half the length of the petals. 3. The sensor according to claim 1, characterized in that in it at the first end of the elastic element two additional slots are made with the formation of six petals evenly spaced around the circumference. 4. The sensor according to claim 1, characterized in that the outer cylindrical surface of the elastic element is stepped, wherein a step of a larger diameter Pi is located at its second end, and a smaller De is at the first end, and the ratio Di / D2 is 1.05 .. Ya Fi g. 2 5-6 Vve.j