KR20120077035A - Inductive sensor for angle or displacement using switching device - Google Patents

Abstract

PURPOSE: An inductance mode sensor for detecting displacement using a switching device is provided to use a switching device having a simple structure for oscillation, thereby preventing a whole structure of a sensor from being complicated even in case of miniaturizing a sensing coil. CONSTITUTION: An inductance mode sensor for detecting displacement using a switching device(50) comprises a sensing coil(10), a coupler, and a signal processor(40). The sensing coil is composed of a LC circuit. The switching device periodically turns on/off power being supplied to the sensing coil. The coupler is installed by being spaced from the sensing coil. The coupler influences to an inductance value generated in the sensing coil by rotating or moving. The signal processor being connected to and installed in the sensing coil outputs a rotary angle and a moving distance of a coupler by calculating with the changed inductance value generated in the sensing coil.

Description

Inductive Sensor for Angle or Displacement Using Switching Device

The present invention relates to an inductance displacement sensor using a switching element, the structure is simple, can be miniaturized, and relates to an inductance displacement sensor using a switching element that can reduce the current consumption.

In general, in the case of a steering wheel, a braking device, and various mechanical devices of a vehicle, it is very important to accurately measure the rotation angle or the linear moving distance, so that accurate control can be performed.

Therefore, various angle sensors are installed and used to measure the rotation angle of the rotating body, and various linear displacement sensors are installed and used to measure the linear travel distance.

For example, an angle sensor using light emission and light reception, an inductance displacement detection sensor using an inductance of a coil, and the like are used.

Examples of the conventional inductance displacement sensor include various methods such as Korean Patent Nos. 10-0929163, 10-0938597, 10-0988573, Patent Publication Nos. 10-2010-0003172, 10-2010-0033907, and the like. An inductance angle sensor with over structure is disclosed.

Conventional inductance displacement sensor is configured by placing the receiving coil on the excitation coil, and a coupler on it. An oscillation circuit is connected to the excitation coil to apply an oscillation voltage at a predetermined frequency.

RC oscillator (RC Oscillator), LC Oscillator (LC Oscillator), Crystal Oscillator (Crystal Oscillator), Hartley Oscillator (Hartley Oscillator), Colpitts Oscillator (Colpitts Oscillator) is used.

In the structure described above, a change occurs in the inductance value of the receiving coil as the coupler rotates or moves, and the rotation angle or the linear movement distance of the rotating body is measured using the same.

In recent years, the demand for miniaturization of the inductance displacement sensor has been increased, but in order to reduce the size of the excitation coil, the frequency has to be increased, but the structure of the oscillation circuit for oscillating a high frequency is complicated.

Therefore, there is a limit to miniaturization in the conventional inductance displacement sensor.

The present invention has been made in view of the above point, by using a switching element as the oscillation circuit and by configuring the configuration to be able to measure the rotation angle or the moving distance by measuring the change of the time constant switching is capable of miniaturization and miniaturization The present invention provides an inductance displacement sensor using an element.

An inductance displacement sensor using a switching element according to an embodiment of the present invention periodically turns on / off a sensing coil composed of an LC circuit or an LC tank and a power supplied to the sensing coil. A switching element configured to be spaced apart from the sensing coil, and a coupler for changing a value of the inductance generated in the sensing coil as it is rotated or moved, and an inductance value connected to the sensing coil and generated in the sensing coil. It includes a signal processor that calculates and outputs the rotation angle or the moving distance of the coupler using the change.

As the switching element is periodically turned on / off, resonance occurs in a sensing coil composed of an LC circuit, and oscillation is performed at a constant resonance frequency.

According to the inductance displacement sensor using a switching device according to an embodiment of the present invention, since the switching device uses a relatively simple structure for oscillation, the overall structure is not complicated even when the sensing coil is downsized, and the overall system is downsized. Or it is possible to miniaturize.

In addition, according to the inductance displacement sensor using the switching element according to the embodiment of the present invention, since the switching element is used for oscillation, current consumption only occurs when resonance occurs (the conventional oscillation circuit is continuously operated. It is possible to reduce the consumption of current as a whole).

1 is a block circuit diagram conceptually showing an inductance displacement sensor using a switching device according to an embodiment of the present invention.
2 is a perspective view showing an example of a sensing coil in an inductance displacement sensor using a switching device according to an embodiment of the present invention.
3 is a circuit diagram conceptually illustrating an example of using the sensing coil shown in FIG. 2 in an inductance displacement sensor using a switching device according to an embodiment of the present invention.
4 is a graph showing a change in time constant and envelope (f (t)) according to on / off operation of a switching element in an inductance displacement sensor using a switching element according to an embodiment of the present invention.

Next, a preferred embodiment of an inductance displacement sensor using a switching device according to the present invention will be described in detail with reference to the accompanying drawings.

First, as shown in FIG. 1, an inductance displacement sensor using a switching device according to an embodiment of the present invention includes a sensing coil 10, a switching device 50, a coupler 30, and a signal processor 40. )

The sensing coil 10 is composed of an LC circuit or an LC tank.

For example, the sensing coil 10 has a structure in which the coil L and the resistor R are connected in series, and the capacitor C is connected in parallel, and the coil L and the coil L are spaced apart. It is possible to implement by using a variety of circuits, such as the structure that is arranged to generate inductance.

The switching device 50 performs a function of periodically turning on / off the power supplied to the sensing coil 10.

The switching element 50 may be turned on and off at high speed (TR), field effect transistor (FET), solid state relay (SSR), junction field effect transistor (JFET), and metal-oxide semiconductor field effect (MOSFET). It is possible to select and use among various well-known semiconductor devices, such as a transistor, a metal semiconductor field effect transistor (MESFET), and an insulated gate bipolar transistor (IGBT).

When the power supply to the sensing coil 10 consisting of the LC circuit from the switching device 50 is periodically turned on / off, the oscillation is performed at a constant resonance frequency in the LC circuit of the sensing coil 10.

The sensing coil 10 may be constituted only by the excitation coil, may be constituted only by the receive coil, or may be configured by combining the excitation coil and the receive coil.

For example, as illustrated in FIGS. 2 and 3, the sensing coil 10 may be configured by combining the excitation coil 12 and the reception coil 14.

However, in the embodiment of the present invention, the configuration of the sensing coil 10 is not limited thereto, and it is possible to configure the female coil and the receiving coil alone or in various shapes and combinations, and the shape of the sensing coil 10 There is no limit to the combination.

The excitation coil 12 constituting the sensing coil 10 is installed in a state of being wound many times. For example, the excitation coil 12 is used by winding in a circle, square or triangle.

The receiving coil 14 is installed at intervals with the excitation coil 12.

The receiving coil 14 generates inductance L due to induced electromotive force when power is supplied to the excitation coil 12.

The receiving coils 14 may be configured in a pair formed and arranged in a symmetrical shape. For example, the receiving coils 14 may be formed in pairs in a shape that equally divides the shape of the excitation coil 12.

The coupler 30 is installed at intervals from the sensing coil 10.

The coupler 30 is installed to be rotatable or movable to change the inductance value generated in the sensing coil 10.

Since the excitation coil 12, the receiving coil 14, the coupler 30 and the like can be implemented by applying a configuration commonly used in a variety of inductance-type displacement detection sensors, a detailed description thereof will be omitted.

The signal processor 40 is connected to the sensing coil 10.

As the coupler 30 rotates or moves, a change occurs in a resonant frequency oscillated by the on / off operation of the switching element 50 in the sensing coil 10, and in the signal processor 40, By detecting a change in resonance frequency or a change in inductance value generated in the sensing coil 10 and processing the same, the rotation angle or the moving distance of the coupler 30, and whether the coupler 30 is approached or the like are output. .

In the signal processor 40, a change in inductance generated by the sensing coil 10 according to rotation or movement of the coupler 30 may be changed to a constant voltage change.

The signal processor 40 may be further provided with a level adjusting unit for adjusting an offset and a gain in accordance with a desired output range.

Next, a process of detecting a rotation angle, a moving distance, and approaching of the coupler 30 by applying an inductance displacement detection sensor using a switching device according to an embodiment of the present invention configured as described above will be described.

In general, transients in RC response (circuit consisting of resistor R and capacitor C) and RL circuit (circuit consisting of resistor R and coil L) (resistance until steady state) The term attenuates at the ratio (exp ^{-t / τ} ). Here, t represents elapsed time ^, τ is called a time constant ^{, and} τ is a time when the value for the initial value becomes exp ⁻¹ (63.2%). In the RC circuit, τ = RC, and in the RL circuit, τ = L / R.

In the case of the RLC closed circuit, if the terms are summarized with respect to the voltage, the following equation (1) is given.

In the above equation 1, the time response is represented by the time function s, and the Laplace inverse transform is performed.

Equation (2) is rearranged using a damping ratio (ζ) and a non-braking natural frequency (ω0) and can be expressed as Equation 3 below.

Using the above Equation 3, the condition of 0 <ζ <1, which is an underdamped condition, is obtained as shown in Equation 4 below.

In the inductance displacement sensor using a switching device according to an embodiment of the present invention, the power applied to the sensing coil 10 in a waveform as shown in FIG. 4 whenever the switching device 50 is turned on or off. This change causes periodic resonance of the LC circuit (LC circuit) to occur in the sensing coil 10, thereby obtaining a specific resonance frequency.

In other words, even if a separate oscillation circuit is not configured, a resonance frequency oscillated at a specific frequency in the sensing coil 10 can be obtained only by turning on / off the switching element 50.

As the coupler 30 rotates or moves, the resonant frequency of the sensing coil 20 changes, and the signal processor 40 calculates and processes the rotation angle, moving distance, and approach of the coupler 30. It is possible to provide an output for.

In the case where the receiving coil 14 is installed in the sensing coil 20, the inductance L value of the receiving coil 14 changes as the coupler 30 rotates or moves, and the receiving coil 14 It is also possible to arithmically process the signal obtained from the signal processor 40 to obtain an output value of the rotation angle or the moving distance of the coupler 30.

When the signal processor 40 integrates the change of the time constant through an integrator, the result is expressed as in Equation 5 below.

In Equation 5, A represents the maximum amplitude of the time constant waveform shown in FIG.

The above equation (5) is summarized with respect to the time constant (tau), and is expressed as shown in the following equation (6).

Inductance displacement sensor using a switching device according to an embodiment of the present invention periodically as the coupler 30 rotates (or moves) the integral value of the time constant τ obtained as shown in Equation 6 above. By using the change, it is made to sense the rotation angle (or movement distance) of the coupler 30.

In the case of configuring the coupler 30 to detect the rotation angle, the moving distance, the access status, etc. using Equation 6, the signal processor 40 may be implemented using an envelope detector. .

The signal processor 40 may be configured to check the change of the inductance value (L value) transmitted from the sensing coil 10 by using a comparator and an integrator to calculate a rotation angle or a moving distance of the coupler 20. Do.

When the signal processor 40 is implemented by using a comparator and an integrator, the waveform of the time constant τ shown in FIG. 3 is obtained as a square wave (square wave).

The signal processor 40 may be implemented using an FM demodulator (Frequency Modulation Demodulator) to process the resonant frequency changed according to the position of the coupler 30 as a change in voltage level.

The signal processor 40 selects one of a phase locked circuit (PLL), a radio detector, a poster-silley discriminator, a time-delay demodulator, and the like. It is also possible to implement using this.

In the above, a preferred embodiment of an inductance displacement sensor using a switching element according to the present invention has been described. However, the present invention is not limited thereto, and the present invention is not limited thereto and may be modified in various ways within the scope of the claims and the accompanying drawings. It is possible and this also belongs to the scope of the present invention.

10-sensing coil, 12-female coil, 14-receiving coil, 30-coupler,
40-signal processor, 50-switching element

Claims (3)

A sensing coil composed of an LC circuit,
A switching element for periodically turning on / off power supplied to the sensing coil;
A coupler for changing the inductance value generated in the sensing coil as installed and spaced from the sensing coil and rotating or moving;
And a signal processor connected to the sensing coil and configured to calculate and output a rotation angle or a moving distance of the coupler by using a change in the inductance value generated by the sensing coil. The method according to claim 1,
The switching device may be turned on and off at high speed (TR), field effect transistor (FET), solid state relay (SSR), junction field effect transistor (JFET), and metal-oxide semiconductor field effect transistor (MOSFET). Inductance displacement sensor using a switching element selected from among MESFET (Metal Semiconductor Field Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor). The method according to claim 1,
The signal processor includes an envelope detector, a combination of a comparator and an integrator, a frequency modulator demodulator, a phase locked loop, a radio detector, a poster-silie discriminator. An inductance displacement sensor using a switching element composed of one of a Seeley discriminator and a time-delay demodulator.

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