SU978048A1 - Shaft rotation angle and speed pickup - Google Patents

Description

(54) SPEED AND ROTATION ANGLE OF SHAFT

one

The invention relates to a measuring technique and can be used in contactless synchronization devices of various processes with the angular position of a rotating element, for monitoring and controlling various devices in which one or several positions of a moving element must be accurately and stably detected, or in devices for measuring angular

shaft rotation speed.

A known shaft speed sensor comprising a rotor, a stator, made in the form of a cylindrical magnetic core with a central rod of a permanent magnet, with a cylindrical coil and with end teeth. Using the sensor it is possible to measure the angle of rotation of the shaft 1.

The main disadvantages of such a sensor are limited scope due to the inability to measure the shaft speed when the sensor is installed on its side surface in case of difficult access to the shaft end, and the resolution of the angle of rotation is not high.

The closest to the proposed technical entity is a speed sensor and a shaft angle of rotation, comprising a gear rotor, a stator having a coupling cable with a winding and a nozzle at the working end C2J.

The main disadvantage of the known sensor is the low resolution of measuring the angle of rotation of the shaft due to the fact that when the sensor is operated with a very small gap between the rotor and stator, commensurate with the rotor beats, the EMF is useful, induced in the sensor winding when the roto-teeth interact and the stator plate is distorted due to a change in the gap between the rotor and the stator as a result of the shaft beat and inaccuracy of the rotor manufacture, which reduces the resolution of the sensor.

Increasing the gap between the rotor and the stator to sizes that are at least as large as the order of the driver, reduces the distortion in the useful emf, but significantly reduces the amplitude of the useful emf.

In addition, the magnetic flux created by a permanent magnet, to

30, the working gap is not fully supplied: a part of it is closed in other ways, including by air, and therefore the magnetic flux density in the magnetic core is reduced. A sharp decrease in the cross-sectional area when moving from the cylindrical working end of the magnetic conductor to the rectangular nozzle leads to an increase in the scattering fluxes and, consequently, a decrease in the useful magnetic flux in the air gap between the stator and the rotor, which reduces the amplitude of the useful signal. The purpose of the invention is to increase the resolution of measuring the angle of rotation and the size of the output signal. The goal is achieved by the fact that in the proposed speed sensor and shaft angle of rotation, comprising a gear rotor, a stator having a magnetic circuit with a winding and a nozzle on the working end, the magnetic circuit is conical, tapering in the direction of the nozzle, the nozzles are made with a constant cross-sectional area and with the variable shape of the current cross section from the round one, corresponding to the working end of the magnetic circuit, to the rectangular one, whose width is equal to the width of the rotor tooth, while the cross sectional area SH is selected from the ratio SH / ST f to the cross-sectional area of the working end of the magnetic circuit, and the number of turns of the winding is made increasing in the direction of the nozzle. FIG. 1 shows the speed sensor and the angle of rotation of the shaft, a general view; in fig. 2 is a section A-A in FIG. one ; on fig.Z --section bb in figure 1. The speed sensor and the angle of rotation of the shaft contains rotor 1 made of ferromagnetic material and mounted on the controlled shaft with protrusions 2 and a stator, which is the sensor element itself, mounted on some non-movable bracket (not shown). The stator has a coaxially arranged ring-shaped magnet 3 (for example, from an alloy of rare-earth material 5 (Co, polarized in the axial direction, magnetic conductor 4 with nozzle 5. At the same time, magnetic conductor 4 is made conical, narrowing in the direction of nozzle 5. Nozzle 5c side surface 6 is made with preservation of a constant cross-sectional area and with a changing shape of the current useful section of a circular, corresponding to the working end of the magnetic circuit to rectangular 7, whose width is approximately equal to the width of the tooth 2 1 and the length is less than the length of the projections 2 of the Pj 1 of 10-20%. On the magnetic core 4 there is a winding 8, the number of turns of which is made increasing in the direction of the nozzle 5. The stator is placed in the housing 9, made of non-magnetic material with high specific electric resistance (for example, from steel having a non-magnetic austenite structure). The stator housing 9 has a groove 10 for a corresponding orientation of the nozzle 5 along the teeth of the rotor 1 when mounting the sensor. The sensor works as follows. The magnetic flux created by the permanent magnet 3 passes through the circuit: magnetic circuit 4 - nozzles 5 - air gap between nozzle 5 and rotor 1 - rotor 1. The magnetic resistance of this circuit depends on the size of the air gap between nozzle 5 and rotor 1, which changes Depending on whether the nozzle 5 is opposite the end 7 of the nozzle 5, the protrusion 2 of the rotor 1 or trough. When the controlled shaft rotates and the toothed rotor 1 mounted on it, periodic changes in the air gap between the rotor 1 and the stator nozzle 5 and the associated changes total magnetic resistance cause proportional changes of magnetic flux in the coil which induces the EMF sensor 2, the frequency of which depends on the speed of rotation of the shaft and the rotor gear parameters where f - frequency emf in the sensor winding Hz; 2 - the number of protrusions on the sensor rotor; n is the frequency of the rotor, rpm. From this dependence, the rotation frequency of the shaft is determined using a secondary transducer. P 2 The rotation angle of the monitored shaft is determined by the number of pulses calculated from the reference signal (start), where N is the number of sensor pulses CLEARED from the reference signal (from the beginning reference) the number of projections on the rotor of the sensor; angle of rotation of the shaft from the reference position, rad.

Performing a nozzle with profiled side surfaces while maintaining a constant cross-sectional area and making the magnetic conductor conical, tapering in the nozzle direction, provided that the current cross-sectional area of the nozzle is at least not less than the cross-sectional area of the working end of the magnetic circuit, and windings with a number of turns increasing in the direction of the nozzle allow to increase the resolution and the magnitude of the output signal by about 2-4 times results) with serially equipped with sensors of model 1PPT-2 (TU 25-04-3363-78 К.

Comparative tests of the claimed and serial sensors are carried out.

As a result of the tests, the following was revealed. With a shaft rotation frequency of 2000 rpm, the output signal Go value of the proposed sensor is 15 V, the serial sensor is 5 To obtain an output signal from the sensor of at least 4 V with a clearance between the stator nozzle and the rotor protrusions 0.5 mm the rotor can be brought to the proposed sensor up to 1 mm, serial - at least 3 mm.

Thus, the resolution of the proposed sensor is 3 times better ("3: lj.

Claims (2)

1. Authors certificate of USSR 0 527661, cl. С; 01 Р 3/44, 1975. 2. Patent of the USSR No. 566535, cl. S, 01 P 3/42, 1974 (prototype).