RU1809335C - Device for measuring torque and rotation angle on rotating shafts - Google Patents

Abstract

Usage: in information-measuring technology, control systems for measuring by one device the torque and angle of rotation on any rotating shafts of machines and mechanisms. SUBSTANCE: device comprises an elastic insert placed on a shaft, a magnetic conductor in the form of a fixed annular element having the shape of a hollow cylinder, a movable conductive ring, an excitation winding, a measuring winding, disk-shaped covers with cylindrical bushings placed symmetrically on both sides of the shaft between the movable a current-conducting ring and an elastic insert and provided with coaxial slots in the ends, and the middle part of the movable ring element is made in the form of a hollow cylin pa provided with slits along the center line and covering the elastic insert, the movable conductive present in a ring formed spiral groove. 5 ill.

Description

The invention can be used in information technology, control systems for measuring, with a single device, the torque occurring on the rotating shafts and the angle of rotation of these shafts at the same time. mechanical assembly mechanized tools on any rotating shafts of machines and mechanisms.

The purpose of the invention is the expansion of functionality by measuring the angle of rotation and increasing sensitivity.

Thus, the construction has two functions. One function is the symmetric supply of magnetic fluxes from two sides to a movable conductive ring with a helical groove, and the second function is the screening of magnetic fluxes from flowing them along a shaft that transmits force.

When considering the effect of the shield, which is a movable conductive ring, on an alternating magnetic flux, it is convenient to assume that the shield for magnetic flux is a magnetic barrier. When idealizing the nature of the processes, it can be assumed that the magnetic flux does not pass through the screen. The width of the screw groove is already sufficiently 1.5 mm. Magnetic flux passes through the screw groove and with the speed of rotation of this screw groove, EMF is induced on the measuring winding.

Since the field windings of the device for measuring torque and angle of rotation on the rotating shafts are connected in a differential manner, and the elastic insert is also structurally made

with

about you

differentially, then the whole device can be called differential. Differential devices have advantages; the linear part of the characteristic is obtained over a larger area, the electrodynamic force acting on the screen is reduced, since in differential systems, it is the difference of forces from the side of half of the magnetic circuit and half of the differential elastic insert.

A device for measuring torque and angle of rotation on rotating shafts is shown in FIG. 1 and consists of a fixed ring element 1 serving as a magnetic circuit, disk-shaped covers 2, with cylindrical bushes 3, bushings 4, with rolling bearings 5 pressed into them, the middle part of the magnetic circuit with cuts along axial line b, two symmetrically arranged field windings 7, measuring a winding 8, a movable conductive ring 9, with a slotted screw groove 10, a cracker 11 for securing this movable conductive ring. rings with a slotted screw groove, elastic insert 12, the place of attachment of the elastic insert by spot welding 13 to the shaft 14, transmitting force ..

In FIG. 2 shows the middle part of the magnetic circuit with cuts along the center line; in FIG. Figure 3 shows a movable conductive ring with a slotted helical groove; in FIG. 4 shows disk-shaped covers with cylindrical bushings; in FIG. 5 shows waveforms of a device for measuring torque and angle of rotation of rotating shafts taken from a measuring winding.

The device operates as follows. When applying an alternating voltage of a rectangular shape with a duty cycle of 2 to the field windings 7, included in the differential circuit, in a fixed ring element 1 serving as a magnetic circuit, two magnetic fluxes Фт and Фг (Fig. 1) are directed opposite to each other, in the opposite direction, which are fed through disk-shaped covers 2, with cylindrical bushings 3, magnetic fluxes are fed under a movable conductive ring 9 with a slotted slot 10. Since this is a movable current lead botfly present ring with a slotted screw groove disposed .no symmetric relative to the geometric center of the fixed points of the ring 1 serving as a magnetic core, it automatically skazyvaets in the magnetic neutral which in turn coincides with the geometric neutral and a measurable emf. The winding is not induced. By radiating magnetic fluxes, edge

partially due to the effects and not ideal symmetry of the structure, the EMF is partially induced into the measuring winding, and, in particular, through the screw groove in the movable conductive ring, for convenience, we conditionally assume this EMF to be zero (

0 2 mV, which is the value of the second order of smallness).

When rotating in the bearings, which are the rolling bearings 5 of the shaft 14, the elastic insert 5 а a 12 also rotates with it, since it is rigidly connected to the shaft by spot welding 13. In the center of the elastic insert, a movable conductive ring is fixed through the cracker 11 9 with a slotted helical groove 10, also starts to rotate. Due to the magnetic flux brought under the movable conductive ring with a slotted screw groove, EMF is induced on the measuring winding along symmetrical disk-shaped covers 2 with cylindrical bushings 3 in proportion to the speed of rotation of the movable conductive ring 9 with a slotted screw groove 10. The signal waveform Shot 0. taken from the measuring winding are shown in FIG. 5 (6) and (b). Its amplitude Exx will reflect the angle of rotation of the shaft and, accordingly, of all devices located on this shaft.

5 In order that all of the above signals shown on the waveform are shown in FIG. 5, it is more efficient to use them for analysis and re-analysis without preliminary amplification, in the middle part of the magnetic circuit 6, as in the disk-shaped covers 2, through grooves of 0.5 mm wide and at least 8 slots along the axial line are cut . Due to the fact that the middle part of the magnetic wire with cuts along the axial line is galvanically isolated from the flow of eddy currents along it and disk-shaped covers with slots in the ends are also galvanically separated from leakage in them

Because of eddy currents (Fig. 4), it became possible to sharply increase the sensitivity and resolution of the entire device as a whole. This, in turn, made it possible to obtain a sufficient EMF in the measuring winding, the amplitude of which was sufficient to determine the second informative parameter, namely, the angle of rotation of the shaft. Here, the middle part of the magnetic circuit with cuts along the axial line and the disk-shaped covers with slots at the ends ceased to be short-circuited turns (or cylinders), i.e., they did not bypass magnetic fluxes.

Further, under the influence of the load, the elastic insert 12 will experience forces that are on the one hand; where the bridges and their direction coincide with the direction of the moment of forces, they will experience expansion, at the same time, the opposite bridges do not coincide with the direction of the moment of forces, in this case the bridges will experience compression. The middle part of the elastic insert 12, where a movable driving ring 9 is fixed through a cracker 11 with a slotted screw groove 10, is moved to one side or the other from the neutral, depending on the sign of the applied moment of forces. An EMF is proportional to the torque applied to the shaft in the measuring winding. The waveform of the signals taken from the measuring winding is shown in FIG. 5 (6) Exx;

The need to combine functions in one device, such as torque and the angle of rotation of its shaft, is caused by the urgent need that arose in automated mechanical assembly production.

Such devices in mechanical assembly production are used in wrenches and other similar devices to determine the effort on assembled products interactively at the moment of their connection, where it is also necessary to know the rotation angle of the assembled threaded element. This made it possible to relate the determination of the tightening torque of the threaded connection to the tightening force, which is characterized by the expression

MKp Qtg (0 + / o) where MKp is the torque on the drive shaft;

Q is the force at the outlet of the assembly device;

 thread angle;

p is the angle of friction; . dcp is the average diameter of the thread;

ftp - friction coefficient.

As can be seen, the friction coefficient (p arctg fTp) is included in expression (1), which varies widely, both during the process of making a threaded joint and during the transition from one product to another.

This expression (1) represents the dependence of the torque on the key on the tightening force of the threaded joint. In it at 5 10 15 20, 25

30 35 40

45

fifty

55

Nom form does not include friction coefficient. In addition, there is no need to calculate the supporting surface of the ends of the surfaces of the threaded elements. Of all the geometric dimensions, you only need to know the thread pitch

if - & - (p, then Mkr tan p; for fTp (Јt)

M

 Q

where p is the angle by which the assembled product is twisted;

 - the error that occurs when measuring the angle of rotation.

After the tightening force exceeded a certain value corresponding to compression of the joint, the dependence of the moment and tightening force on the rotation angle (f) in the elastic zone takes place linear in nature. On the linear section, the derivative dM / dQ Const. So on devices such as a mechanized tool, it is necessary to measure, in addition to the moment M, the angle of rotation, p; In order not to use the angle measuring sensor in the mechanical assembly tool in the proposed device for measuring torque, the function of measuring the angle of rotation of the drive shaft, by which the force is transmitted to the assembled threaded connection, is also compatible.

In addition to the above, y. devices for simultaneously measuring the torque on the rotating shaft and the angle of rotation, it was still possible to use a movable conductive coil by cutting a helical groove in it, to obtain another conversion function, namely to measure the angle of rotation of the shaft simultaneously with the measurement of torque. In FIG. Figure 5 shows a voltage waveform, where: Un is a rectangular voltage supply with a duty cycle of 2 (a) and (a1); EXx - voltage at the measuring winding in idle mode, without load; ESr - the average value of the output EMF. Hereinafter in FIG. 5, indices without strokes refer to the stresses taken for torque, and with strokes to the measurement of the angle of rotation of the shaft.

Let us consider the operation of a synchronous switching device controlled by a microprocessor. The operation of the switching device in static mode is shown on the waveform. Using a synchronous switching device with a rectangular shape

carrier voltage, suppresses common mode noise and the quadrature component of the output signal. The synchronous switching device is implemented on MOS keys. In FIG. 5 (c) and (d), as well as (c) and (d), the shape of the control voltage hi, ha, as well as hi and ha, are separated in time, which are controlled by pulses from the microprocessor. The capacitor bank of the RC circuit is shown in FIG. 5 (Vci), (Vca) to steady state. In FIG. 5 (e) and (e), the voltage at the output of the switching keys. Moments of time ti; ta; ta; t4 etc. synchronized with the moments of transition through zero of the control voltage, where: Here: CHS is the frequency of the control voltage, co is the frequency of the carrier voltage. The capacitor values are selected from the condition: 1 / (ft) jCCp) R. R. In this case, the voltage components with a frequency u are isolated on the resistor R and at the output of the switching device Uhw, a voltage close to a rectangular voltage with an amplitude ESr is formed. The duration of the fronts of the output voltage is determined only by the speed of the switching device. The structural switching device is presented as an ideal DC link demodulator with a transfer function of the form:

W (P) (P) +1.

By selecting the constant time r mRC, the desired frequency response is obtained over the envelope Lhebix and Ui out, fig. 5 (e) and (e), where: m is the coefficient of proportionality; The Laplace P-operator P j W (P) is the transfer function of the demodulator. After the demodulator, the voltage E "is removed from the capacitor and will be equal to:

Aj

IJftlt;

Bjl

 .

for the public key of the switching device hi and the private h2 in the next

half time period, Aj and Bj ljwt are the components after charging the capacitor of the switching device.

At the output of the switching device with different sampling times, information about the torque on the rotating shafts and the sampling time characterizing the angle of rotation of the shaft is generated.

Microprocessor processing for simultaneously measuring the torque on rotating shafts and turning angles works as follows.

51. When an alternating voltage of rectangular shape with a duty cycle of 2 is applied to the excitation winding, a signal is generated on the measuring winding under applied load to the shaft, the shape of which

10 is shown in FIG. 56 and 56. Here the informative parameter is the amplitude of the averaged value of Еср provided that the sampling transition is at least T / 4, and the informative parameter is

15 is the amplitude of this sample. When measuring torque, cuts along the middle part of the magnetic circuit with cuts along the axial line (Fig. 2) do not affect sensitivity, and vice versa, the intersection of the 20 moving conductive ring and its cut (Fig. 3) give an amplitude surge at the moment of transition process. The duration of this pulse differs significantly (by an order of magnitude) from the duration of the sample

25 informative signal characterizing the dependence of the moment on time. The voltage at a pulse repetition rate of 1500 Hz with a duty cycle of 2 and the sampling time of the informative parameter of torque 30 is 725 / g S t, T2, Fig. 5. Where: TI and ri - for the positive, mr and mr - for the negative half-periods. Sampling time, characterizing the measurement of revolutions of the order of 25 (l S t, ha, Fig. 5, Since

If the information about the torque is enough for 375 / l s, then the time margin for processing this signal is enough for 725 / s and minus 375 and, accordingly, 25 fi s. . The remaining 350 / i sj is quite enough.

40 The sampling amplitude depends on the torque directly proportional to that arising under the influence of the load on the shaft. Thus, we have information about the torque occurring on the rotating shafts.

2. When the shaft of the combined device is rotated to simultaneously measure the torque and the angle of rotation of the shaft, after the microprocessor polls the switching device with a period of T / 4 at the moment the informative signal passes through the slot, an impulse is generated. The pulse duration differs by an order of magnitude from the main sampling period. This

55 emission and its amplitude carry information about the angle of rotation of the shaft inside the magnetic circuit. This happens as follows. When the elastic insert and, accordingly, the movable thioconductive ring with the slotted screw groove rotate, it rotates with it, because it is rigidly connected to the elastic insert. And since the movable current-conducting ring with a slotted screw groove and a slot thickness commensurate with the cut thickness of the middle part of the magnetic circuit with cuts along the center line and overlapping the slotted screw groove, at this moment due to the bulging of the magnetic flux and its shielding, the moment of passage of the slot of the movable conductive ring is formed on a common pulse, which corresponds to one revolution of the movable conductive ring with a slotted screw groove a, and hence the rotation of the shaft. The widths of the slots and their location on the movable conductive ring do not affect the information obtained from the measurement of the torque on the rotating shaft. The amplitude of this surge will characterize the number of revolutions made by the shaft per unit time 1 / p, which is associated with the expression with the angle of rotation of the shaft and the moment of forces on this shaft

(pn (y ± 1 / n).

where rp is the angle of rotation of the shaft and the movable conductive ring, dressed on it; - the pitch of the grooves, with a step equal to one, can be displayed as filling the information signal with pulses, then expression (3) will look like:

p- (p ± 1 / p). (4)

which makes sense, where p is the conjugation module. The magnitude of pp / n determines the discreteness of the interface module, i.e. pitch of cuts of the middle part of the magnetic circuit, divided into n parts, The amplitude of the output signal is related to the revolutions of the rotating shaft as follows: the more often the slot will pass on the fixed ring element, which serves as the magnetic circuit under the slot of the conductive ring, the smaller the amplitude of the ejection.

The goal is thereby achieved. The functionality of such devices in which two functions are combined, in this case the torque and the angle of rotation of the shaft, is obvious. The slit of the movable conducting ring, intersecting the middle part of the magnetic circuit with cuts along the axial line, does not interfere with having an informative parameter about the torque less reliable. These times 5 10 15 20 25

thirty

35

40 45 50 55 cuts significantly reduce the leakage of eddy currents inside the middle part of the magnetic circuit, which increases the resolution of the entire device and also increases its sensitivity due to reduced heating of the stationary ring element serving as the magnetic circuit by eddy currents. Accordingly, the reliability of the entire device as a whole increases.

A device for measuring the torque and angle of rotation on rotating shafts, different from the known one in that it uses the middle part of the magnetic circuit with cuts along the center line, thereby galvanically decoupling, disk-shaped covers with cylindrical bushes and also galvanically decoupling. the ends of which are brought under a movable conductive ring with a slotted screw groove, which will give this design new functional properties, such as the ability to measure the angle of rotation of the shaft . The middle part of the magnetic circuit is obtained as if cut into many parts, retaining jumpers for mechanical communication with the housing of the fixed ring element serving as the magnetic circuit. For eddy currents, a large resistance is formed in the middle part of the magnetic circuit, thereby increasing the flux linkage coefficient between the field windings and the measuring winding, and accordingly, the resolution of the entire device as a whole increases.

The use of a microprocessor made it possible to re-organize the collection of information for analysis and processing of the output signal from the device. This made it possible to use the above expressions (1), (3), (4) to calculate the force and tightening angle of the assembled products with their help. The accumulation of measurement values over a series of measurements can be compared with each other and the measurement results can be averaged according to any law, which significantly improves the measurement accuracy of both the torque generated on the shaft and the angle of rotation of this shaft.

Claims (1)

The claims Device for measuring torque and angle of rotation on rotating shafts, comprising an elastic insert placed on the shaft, a magnetic core in the form of a fixed annular element having the shape of a hollow cylinder, a movable conductive ring, an excitation winding, and a measuring winding other than the fact that, in order to expand functionality by measuring the angle of rotation and increasing sensitivity, disk-shaped covers with cylindrical bushing are introduced into it from two sides of the fixed ring element kami arranged symmetrically on both sides of the shaft between a movable conductive ring and an elastic insert and provided with coaxial slots at the ends, and the middle part of the movable annular element is made in the form of a hollow cylinder placed inside it, equipped with slots along the axial line and enclosing the elastic insert, while in the movable conductive ring made screw groove. VidR