SU748153A1 - Pneumatic stripper for coordinate-type parameter meter placed after turbine impeller - Google Patents

Description

The invention relates to the measurement of pressure in elastic media and can be used in studies of turbomachines around working blades in relative motion (in rotation), as well as guide vanes in absolute motion and in the study of aerodynamics in various devices. A pneumatic plug device measures the full braking pressure and static pressure. Pneumatic devices are known, containing distribution boxes connected to respective pressure gauges. Each box consists of two main parts, rotating together with the shaft of the object under study and the external one — stationary. The pressure through the rotating part of the box is transmitted to the annular chamber and then to the pressure gauge. The annular chamber is sealed by means of oil closures, oil seals or mercury labyrinth seals 1. The disadvantages of these devices are: design complexity; substantial heating of the sealing elements, requiring their forced hydraulic cooling; the possibility of leakage of the measured pressure and the limited range of the magnitude of the transmitted pressure. All this limits the range of operating revolutions of the pneumatic-detachable device and reduces the accuracy of measurements. Contactless information transfer (constant pressure component) from a rotating object can also be achieved using a linear differential transformer (LTD). LTD uses the effect of changing magnetic coupling. The pressure measured by the transducer located on the rotating object is transformed into a change in the position of the ferromagnetic core (attached to the end of the flexible bellows element) relative to the left-facing receiving differential magnetic system located coaxially with a radial clearance relative to the core. It is also known to have a pneumatic-detachable device for a coordinate measuring instrument for parameters behind the impeller of a turbine, which contains a differential transformer with a sleeve and a core core and a membrane supported on both sides by helical springs 2.

However, in sliding bearings, supporting the core with the core in a coaxial position with a constant radial clearance relative to the windings of the BDT during axial displacements of the latter (when measured in absolute and relative movements), some friction is variable in magnitude and time. This phenomenon introduces an error, especially when measuring relatively small pressure values. The use of the bellows in the form of a sensitive flexible and cavity-separating element, the perceived pressure, leads to a slightly increased sensitivity threshold (level of insensitivity). And the cylindrical springs supporting the bottom end of the bellows (to which the core is attached) have a rigidity equal to and greater than the rigidity of the bellows to ensure the linearity of the characteristic in the range of the measured pressure level. The use of certain types of bellows with appropriate geometrical dimensions sometimes leads to a complication of the device design and an increase in its dimensions.

The aim of the invention is to improve the measurement accuracy and simplify the design.

The goal is achieved by the fact that elastic elements are additionally installed on both sides of the membrane, and an elastic support is additionally inserted into the device, on which one of the ends of the core rod is fixed, the other end of which has contact with one of the elastic elements.

FIG. 1 shows a pneumatic device; in fig. 2 elastic element.

In the housing 1 of the device (Fig. 1) are running and measuring nodes. The undercarriage of the device consists of a sleeve 2, a hollow roller 3, along the axis in which a supply pneumatic tube of 4 g is placed at its end, rolling bearings 5, lids in, spacer sleeve 7, tip 8, and coil spring 9, pressing the rotor devices to the extreme right position (according to the drawing) and liquidator axial bearings in rolling bearings. The measuring unit consists of a sleeve 10 flange, a rubber membrane 11, a core core 12, elastic elements 13 and 14, an elastic rod support 15, cylindrical coil springs 16 and 17, an adapter ring 18, a sleeve 19, a spool 20 and a differential transformer (DT) 21 consisting of a shield 22, a ring 23, a shield 24 nuts, a lock nut 25

and screw 26. Gaskets 27 are installed between the elastic elements 13 and 14. The elastic elements 13 and 14 (FIG. 2) are the flange 28, the elastic movable part 29 on which the protrusions 30 are located. The membrane 11 and the elastic elements 13 covering it 14 using two gaskets 27 are clamped tightly with the flanges of the roller 3 and sleeves 10. A rod with an ELM on it with the core 12 rests on the protrusion of the elastic element 13 and the elastic support 15. The spring 16 provides a constant pressure of the core 12 to the elastic element 13 and accordingly to the membrane 11 . Similar the action is also provided by the spring 17. With the help of the spool 20, create the necessary pressure in the hermetically cavity of the spool-membrane for unloading the membrane by pressure during measurements. With the help of the nut 24, it is possible to move the screen 22 along the axis relative to the core core 12. With the help of the nut 25, the position (along the axis) of the screen 22 assembled with the windings DT is fixed. The screw 26 allows the screen 22 to be linearly moved with a transformer 21 along the axis of the device (without turning). Elastic elements 13 and 14 are solid metal structures having a flange 28, an elastic movable part 29 with flexible elements on which protrusions are located. The core core 12 is supported on the outlines of one of the elastic elements (Fig. 2), and a transition ring 18 is mounted on the protrusions of the second elastic element. flexible elements located diametrically, and along the axis - a hole for mounting and soldering the core 12. The elastic support 15 and the elastic element 13, on which the core core 12 rests, are structures with maximum rigidity in the radial and minimum no axial stiffness.

The measured pressure is supplied through a pneumatic tube 4 located in the roller 3 into the cavity formed by the membrane 11. As a result of the applied pressure, the membrane 11 covered by the elastic elements 13 and 14 bends along the axis, moving the core core 12 fixed at its end and the differential transformer 21 converts the movement of the core core 12 into an electrical signal. The pressure transformation (movement of the core core 12 along the axis) into an electrical signal and its repetition in time with high precision ensure

Claims (1)

Claim A pneumatic lifting device for a coordinate 'meter of parameters behind the turbine impeller, containing a differential transformer with a sleeve and a rod heart * com, and a membrane supported on both sides by coil springs, characterized in that, in order to increase the measurement accuracy, and simplify structures, elastic elements are additionally installed on both sides of the membrane, moreover, an elastic support is additionally inserted into the device, on which one of the ends of the core rod is fixed, the other end of which has a contact with one of the elastic members.