RU145255U1 - CAPACITIVE DIFFERENTIAL SHAFT ANGLE SENSOR - Google Patents

Abstract

1. A capacitive differential sensor of the angle of rotation of the shaft, containing a bipolar power supply of alternating sinusoidal voltage, electrically connected through the transformer windings with one pole through constant resistors with two fixed plates made in the form of sectors of conductive material on the dielectric disk of the first sensor stator, and the other pole - with a fixed plate made in the form of a ring of conductive material on the dielectric disk of the second sensor stator, and two not the movable plates of the first stator are connected to the sensor signal processing circuit, and the rotor is mechanically connected to the rotary shaft of the sensor and is located coaxially between the first and second sensor stators with a two-sided air gap, characterized in that the rotor is made in the form of a disk of a double-sided foil dielectric, on one side which is made of a conductive plate of foil in the form of a sector facing the two fixed plates of the first stator of the sensor, and on the other side of the rotor is made of a conductive plate Tin foil in the form of rings, turned towards the fixed plate of the sensor of the second stator, wherein the two rotor plates are electrically connected soboy.2. A capacitive differential shaft angle sensor according to claim 1, characterized in that the air gaps between the conductive plates of the first stator and the rotor and between the conductive plates of the second stator and the rotor are filled with a dielectric film (for example, from Dacron) or elastic dielectric grease.

Description

The utility model relates to measuring technique and can be used to measure the angle of rotation of the shaft of a mechanical device.

Known are capacitive differential sensors of angular rotation of the shaft, which are two series-connected containers constructed structurally in such a way that when the shaft rotates in one direction or another, one of the containers increases and the other decreases. These two capacitors with the help of resistors are included in the bridge mismatch measuring circuit, in which the voltage from the diagonal of the bridge enters the sensor signal processing circuit (V. A. Atsyukovsky. Capacitive differential displacement sensors. Automation library, issue 12. Gosenergoizdat, M., L ., 1960, pp. 20-22.).

Closest to the proposed device in technical essence is a capacitive sensor for measuring angular displacements (RF patent for the invention No. 2289785, IPC 7, G01B 7/30, IV Minaev, GB Soldatov, published on December 20, 2006), containing two coaxially mounted and fixed stator plates, between which a rotor is mounted, mounted on a rotating shaft. A continuous annular metal element is made on one stator plate, and an annular metal element in the form of at least three sectors is made on the other stator plate. The rotor is made in the form of a sector of the disk of a solid, preferably dielectric, material.

This sensor does not give advantages when used in electromechanical devices with limited shaft rotation angles (less than ± 90 °) due to the excessive complexity of electronic signal processing, as well as a small order of capacitance values due to the relatively large air gap due to the structural need to be placed between the stator plates sector dielectric rotor disk.

In the proposed device, the specified technical result is achieved due to the maximum approximation of the conductive plates of the stator and rotor (made in the form of disks of a double-sided foil dielectric) to each other and the differential inclusion of the resistive-capacitive sensor bridge in the error signal processing circuit.

The device of a capacitive differential shaft angle sensor is shown in FIG. 1 (structural and functional diagram) and FIG. 2 (structural diagram).

The capacitive differential sensor of the angle of rotation of the shaft contains a bipolar power source 1 of an alternating sinusoidal voltage, which feeds a resistive-capacitive bridge through the windings of the transformer 2, consisting of R1, R2, C1, C2, C3. In this case, the capacitors are structurally made in an electromechanical device 3, consisting of a first stator 4, a rotor 5, a second stator 6, a rotary shaft 7 and a housing 8. The stators 4, 6 are located in the housing 8 coaxially with the axis of rotation of the shaft 7 and the rotor 5, rigidly connected with a shaft 7 of the mechanical device 9 (Fig. 1).

On the stator 4 (Fig.2a), on the rotor side, two plates 10 and 11 (Fig.2b) are made in the form of sectors of conductive material on a dielectric disk, forming, through an air gap, together with the rotor plate 12 (Fig.2d) capacitors C1 and C2. The plate 12 of the rotor 5, made in the form of a disk of double-sided foil-coated dielectric, has the shape of a sector and faces the stator 4 so that in the neutral position of the rotary shaft 7 forms equal overlap areas through the gap with the plates 10, 11 of the stator 4, i.e. equal capacities C1 and C2. When the shaft rotates in one direction or another (± α), one of the containers (C1 or C2) increases and the other decreases, thereby creating a signal mismatch on the diagonal of the bridge R1, R2, C1, C2.

To eliminate the sliding contact when transmitting the error signal, on the second side of the rotor 5 there is a ring-shaped plate 13 facing the stator 6. The rotor plates 12 and 13 are electrically connected to each other by a wire 14.

On the side of the stator 6, facing the rotor 5, there is a plate 15 (Fig. 2c) in the form of a ring of conductive material on a dielectric disk, which with the plate 13 of the rotor 5, through the gap, forms a capacitor C3 of constant capacity. From the fixed contacts of the plates 10, 11, 15 of the capacitors C1, C2, C3, the outputs of the signals - Outputs are made by wires. 1, Exit 2 and Exit. 3, with Exit. 1 and Exit. 2 are connected to the constant resistors R1 and R2, respectively, and Output. 3 is connected to the winding of transformer 2.

Out 1 and Exit. 2 are also connected to the input of the processing circuit 16 of the mismatch signal of the bridge R1, R2, C1, C2, which converts the voltage from the bridge diagonal into a convenient (required) waveform of the shaft angle sensor 7.

The device operates as follows.

When the bridge R1, R2, C1, C2 is supplied with alternating sinusoidal current from the power source 1 through the transformer 2 and the decoupling capacitor C3, a sinusoidal voltage is generated on the diagonal of the bridge, which contains information about the value of the capacitance of the sensor C1 and C2, the values of which vary in proportion to the angle of rotation of the shaft . The differential diagonal of the bridge is connected to the input of the sensor signal processing circuit 16, in which the phase differences of the bridge arm voltages are measured and, for example, an alternating rectangular signal is generated, the frequency of which is equal to the frequency of the power source 1, and its duration (or duty cycle) is proportional to the angle of rotation of the shaft 7.

When the shaft 7 is in the neutral position, the rotor 5 and the stator 4 of the electromechanical device 3 of the sensor with their plates 10, 11 and 12 through the gap, as a result of a symmetrical mutual arrangement, create equal capacities C1 and C2. In this case, the signal processing circuit 16 will generate an alternating rectangular signal with a duty cycle equal to two, i.e. its duration will be equal to a pause.

With the angular displacement of the shaft 7 in one direction or another by an angle ± α (within ± 90 °), the plate 12 of the rotor 5 will move relative to the plates 10 and 11 of the stator 4, violating the symmetrical mutual arrangement of the plates and creating different values of capacitances C1 and C2. In this case, the signal processing circuit 16 will generate an alternating rectangular signal at the output, the duty cycle of which will be either less or more than two, depending on the direction of rotation of the shaft 7 from the neutral position and will be proportional to the angle of rotation.

Claims (2)

1. A capacitive differential sensor of the angle of rotation of the shaft, containing a bipolar power supply of alternating sinusoidal voltage, electrically connected through the transformer windings with one pole through constant resistors with two fixed plates made in the form of sectors of conductive material on the dielectric disk of the first sensor stator, and the other pole - with a fixed plate made in the form of a ring of conductive material on the dielectric disk of the second sensor stator, and two not the movable plates of the first stator are connected to the sensor signal processing circuit, and the rotor is mechanically connected to the rotary shaft of the sensor and is located coaxially between the first and second sensor stators with a two-sided air gap, characterized in that the rotor is made in the form of a disk of a double-sided foil dielectric, on one side which is made of a conductive plate of foil in the form of a sector facing the two fixed plates of the first stator of the sensor, and on the other side of the rotor is made of a conductive plate Tin foil in the form of rings, turned towards the fixed plate of the sensor of the second stator, wherein the two rotor plates are electrically interconnected. 2. A capacitive differential shaft angle sensor according to claim 1, characterized in that the air gaps between the conductive plates of the first stator and the rotor and between the conductive plates of the second stator and the rotor are filled with a dielectric film (for example, from Dacron) or elastic dielectric grease.