JP2017219465A - Sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor capable of determining whether or not a predetermined substance is present. SOLUTION: A sensor 1 outputs a first signal when a first substance is present over a detection electrode 11 having a detection electrode and a ground electrode isolated from each other and the detection electrode and the ground electrode. If a second substance is present across the detection electrode and the ground electrode, a second signal is output, and if a third substance is present across the detection electrode and the ground electrode. Compares the signal output unit 12 that outputs the third signal, the detection unit 13 that rectifies the signal output from the signal output unit 12, the signal rectified by the detection unit 13, and the preset reference voltage. A determination unit 14 for determining whether or not the substance existing over the detection electrode and the ground electrode is the first substance is provided. [Selection diagram] Fig. 2

Description

  The present invention relates to a first material having a predetermined dielectric constant and conductivity, a second material having a dielectric constant smaller than that of the first material, and a dielectric larger than the dielectric constant of the first material. The present invention relates to a sensor for determining a conductivity of a first substance and a third substance having a conductivity greater than that of a second substance.

  Conventionally, a level sensor has been used for detection of a storage level of a substance stored in a container and detection of a substance circulating in a pipe. One type of level sensor is a capacitance type (for example, Patent Document 1).

  The capacitance-type liquid level sensor described in Patent Literature 1 includes a sensor main body and a sensor circuit that detect a liquid level in a container that contains a liquid based on a change in capacitance. The sensor body detects the capacitance between the detection electrode and the ground electrode provided on the container, and the sensor circuit converts the capacitance detected by the sensor body into an electrical signal, and the liquid is generated based on the electrical signal. Detect face level.

JP 2013-167651 A

  The technique described in Patent Document 1 detects a liquid level (corresponding to the “storage level” in the present application) based on the rate of change in capacitance. However, for example, when water is mixed in a container storing oil, the dielectric constant of oil is different from that of water, so that it is possible to appropriately detect whether the oil is stored up to the position of the level sensor. It is necessary to include a determination unit that distinguishes between oil and air (in an empty state) and a determination unit that distinguishes between oil and water, and the configuration is complicated. In addition, for example, when water flows through a pipe through which oil flows, since the permittivity of oil and water is different, in order to appropriately detect whether oil is flowing, oil and air (oil It is necessary to include a determination unit that distinguishes between a non-circulating state and a determination unit that distinguishes between oil and water, and the configuration is complicated.

  Therefore, a sensor capable of determining whether or not a predetermined one of at least three substances is present with a simple configuration is required.

  A characteristic configuration of the sensor according to the present invention includes a first substance having a predetermined dielectric constant and conductivity, a second substance having a dielectric constant smaller than that of the first substance, and the first substance A sensor having a dielectric constant greater than a dielectric constant of the substance, and discriminating between a conductivity of the first substance and a third substance having a conductivity greater than the conductivity of the second substance, A detection unit having a detection electrode and a ground electrode insulated from each other, and a first signal having a predetermined amplitude value when the first substance exists across the detection electrode and the ground electrode When the second substance is present across the detection electrode and the ground electrode, a second signal having an amplitude value smaller than the amplitude value of the first signal is output, and the detection electrode And when the third substance is present across the ground electrode Includes a signal output unit that outputs a third signal having an amplitude value smaller than the amplitude value of the second signal, a detection unit that rectifies the signal output from the signal output unit, and a signal that is rectified by the detection unit A determination unit that compares a signal with a preset reference voltage to determine whether or not the substance present across the detection electrode and the ground electrode is the first substance. It is in.

  With such a characteristic configuration, a state in which the first substance is present across the detection electrode and the ground electrode, and a state in which the second substance is present across the detection electrode and the ground electrode, The signal output from the signal output unit can be made different for each of the state in which the third substance is present across the detection electrode and the ground electrode. Therefore, it is possible to determine whether or not the first substance is present across the detection electrode and the ground electrode based on the signal output from the signal output unit.

  Further, the signal output unit is configured using an LC oscillator, and the LC oscillator outputs the first signal that oscillates according to a capacitance based on a dielectric constant of the first substance, and the second signal is output from the second signal. It is preferable that the second signal oscillating according to the capacitance based on the dielectric constant of the substance is output, and the third signal is output according to the conductivity of the third substance. .

  With this configuration, the signal output unit has the first signal, the second signal, and the second signal according to the dielectric constant and conductivity of each of the first substance, the second substance, and the third substance. The third signal can be output. Therefore, the determination unit compares the signal output from the signal output unit with a predetermined reference voltage, so that the determination unit determines whether the first substance is present across the detection electrode and the ground electrode. It becomes possible to discriminate.

  Further, the amplitude value of the second signal is set so that the potential of the signal obtained by rectifying the second signal becomes smaller than the reference voltage when the detection unit is arranged in the portion filled with the third substance. It is preferable to have a setting unit for setting.

  With such a configuration, since the reference voltage is set between the first signal and the second signal, when the first substance is present across the detection electrode and the ground electrode, the detection electrode It is possible to appropriately determine when the second substance or the third substance is present across the ground electrode based on the amplitude of the signal output from the signal output unit.

It is the figure which showed the example at the time of arrange | positioning a sensor to a container. It is the block diagram which showed the structure of the sensor typically. It is the figure which showed the output of the signal output part and the detection part. It is the figure which showed the example at the time of arrange | positioning a sensor to piping.

  The sensor according to the present invention has a function of determining whether or not the first substance, which is the intended substance, is present from the first substance, the second substance, and the third substance. Yes. Hereinafter, the sensor 1 of the present embodiment will be described. In the following, for ease of understanding, the first substance is “oil” having a predetermined dielectric constant and conductivity, and the second substance is a dielectric constant smaller than the dielectric constant of the first substance. The third substance has a dielectric constant greater than that of the first substance and has a conductivity greater than the conductivity of the first substance and the conductivity of the second substance. ”.

  FIG. 1 shows an example in which it is determined whether or not oil is stored in the container 2 using the sensor 1. In the present embodiment, the sensor 1 is provided on the side surface 5 of the container 2. Of course, it may be provided on the bottom 3 side or the top 4 side, or may be appropriately provided in a place where it is desired to detect.

  Here, the sensor 1 is a so-called capacitance type level switch. Since this type of capacitance type level switch is well known, detailed description will be omitted, but a resistance value and a capacitance value between a detection electrode 11A and a ground electrode 11C, which will be described later, are determined by the sensor 1 in the container 2. When the substance to be detected (corresponding to “oil”) is stored up to the position where is provided, and when the substance not to be detected (corresponding to “water”) is stored or empty (container 2 Is equivalent to when the air is filled with “air”. The sensor 1 detects whether or not the substance to be detected has reached the position of the sensor 1 based on such a change in resistance value and capacitance.

  FIG. 2 is a block diagram schematically showing the configuration of the sensor 1. As shown in FIG. 2, the sensor 1 is configured to include functional units such as a detection unit 11, a signal output unit 12, a detection unit 13, a determination unit 14, and a setting unit 15.

  The detection unit 11 is inserted into the container 2 as shown in FIG. 1 and detects a substance at the inserted position. In the present embodiment, the detection unit 11 includes a detection electrode 11A and a ground electrode 11C that are configured in a rod shape as shown in FIG. 1 and are insulated from each other. The detection electrode 11A and the ground electrode 11C are insulated by the insulating portion 11B. In this embodiment, the detection part 11 is arrange | positioned in order of the detection electrode 11A, the insulation part 11B, and the ground electrode 11C from the said rod-shaped front end side. When the inner wall portion of the container 2 is made of metal, the ground electrode 11C may be connected to the inner wall portion.

  The detection unit 11 detects a resistance value and a capacitance value between the detection electrode 11A and the ground electrode 11C. These resistance values and capacitance values vary according to the conductivity and dielectric constant of the substance between the detection electrode 11A and the ground electrode 11C. Based on such changes in conductivity and dielectric constant, the sensor 1 can detect whether or not the oil storage level has reached the position of the detection unit 11 in the container 2.

  The signal output unit 12 outputs a signal corresponding to the substance existing across the detection electrode 11A and the ground electrode 11C. FIG. 3 shows a signal output by the signal output unit 12. The signal output unit 12 outputs a first signal having a predetermined amplitude value when oil is present across the detection electrode 11A and the ground electrode 11C. “Oil is present across the detection electrode 11A and the ground electrode 11C” means that the space between the detection electrode 11A and the ground electrode 11C is filled with oil, that is, in this embodiment, the container 2 means that oil is stored up to the position where the detection unit 11 is inserted.

  Here, the signal output unit 12 is configured using an LC oscillator. This LC oscillator incorporates an inductor having a predetermined L value. The electrostatic capacity is an electrostatic capacity based on the dielectric constant of an object existing across the detection electrode 11A and the ground electrode 11C. Accordingly, the LC oscillator outputs a first signal that oscillates according to the capacitance based on the dielectric constant of the oil when oil is present across the detection electrode 11A and the ground electrode 11C. Specifically, the dielectric constant of oil is, for example, about 2 to 4, and the first signal oscillates according to this dielectric constant. In the example of FIG. 3, the amplitude value of the first signal is indicated as A [Vpp]. In the example of FIG. 3, only the AC component superimposed on the DC component is shown.

  Further, the signal output unit 12 outputs a second signal having an amplitude value smaller than the amplitude value of the first signal when air exists between the detection electrode 11A and the ground electrode 11C. “There is air between the detection electrode 11A and the ground electrode 11C” means that the space between the detection electrode 11A and the ground electrode 11C is filled with air. That is, “the state in which the space between the detection electrode 11 </ b> A and the ground electrode 11 </ b> C is filled with air” means that the storage level of the oil stored in the container 2 is higher than the position of the detection unit 11 in this embodiment. This also means that the position of the detection unit 11 is filled with air. When air is present across the detection electrode 11A and the ground electrode 11C, the LC oscillator outputs a second signal that oscillates in accordance with a capacitance based on the dielectric constant of the air. Specifically, the dielectric constant of air is about 1, and the second signal oscillates according to this dielectric constant. In the example of FIG. 3, the amplitude value of the second signal is indicated as B [Vpp]. However, A> B.

  Further, the signal output unit 12 outputs a third signal having an amplitude value smaller than the amplitude value of the second signal when water is present across the detection electrode 11A and the ground electrode 11C. “Water exists between the detection electrode 11A and the ground electrode 11C” means that the space between the detection electrode 11A and the ground electrode 11C is filled with water. That is, “the state where the space between the detection electrode 11 </ b> A and the ground electrode 11 </ b> C is filled with water” means that, in this embodiment, water is mixed in the container 2 in which oil is stored, and this water storage level is Means that the position of the detection unit 11 has been reached. Here, water has a dielectric constant of about 80. For this reason, the capacitance is greatly increased, and the LC oscillator seems to output a signal that swings according to the dielectric constant, but the conductivity of water is several μ [S / cm] to several hundred μ. [S / cm] and very large for air and oil. For this reason, when water exists over the detection electrode 11A and the ground electrode 11C, the oscillation amplitude becomes small, and the LC oscillator outputs the third signal according to the conductivity of the water. In the present embodiment, the third signal refers to a signal with no DC level amplitude, and corresponds to, for example, a signal having a peak value of 0 [V] or a DC signal having a constant value.

  Returning to FIG. 2, the detector 13 rectifies the signal output from the signal output unit 12. The signal output from the signal output unit 12 is transmitted to the detection unit 13. The detector 13 can be configured by, for example, a peak hold circuit that detects a peak value of an input signal, or a smoothing circuit that smoothes an input signal. In any case, since the peak hold circuit and the smoothing circuit are known, the description thereof is omitted.

  FIG. 3 shows the output of the signal output unit 12 when the object existing between the detection electrode 11A and the ground electrode 11C is oil, air, and water, as described above. The output of the detection unit 13 when the output of is rectified by the detection unit 13 is also shown.

  That is, when oil exists between the detection electrode 11A and the ground electrode 11C, the output of the detection unit 13 is a signal obtained by holding the peak value of the first signal or a smoothed signal A / 2. [V]. When air exists between the detection electrode 11A and the ground electrode 11C, the output of the detection unit 13 is a signal that holds the peak value of the second signal or is a smoothed signal B / 2. [V]. When water is present across the detection electrode 11A and the ground electrode 11C, the output of the detection unit 13 is a signal that holds the peak value of the third signal or a DC level that is a smoothed signal. Output. In the present embodiment, as shown in FIG. 3, the third signal is 0 [V] when water is present across the detection electrode 11 </ b> A and the ground electrode 11 </ b> C. The output of the detector 13 is also 0 [V].

  Returning to FIG. 2, the determination unit 14 compares the signal rectified by the detection unit 13 with a preset reference voltage to determine whether or not the object existing across the detection electrode 11 </ b> A and the ground electrode 11 </ b> C is oil. Determine whether. The signal rectified by the detector 13 is an output of the detector 13 as shown in FIG. The reference voltage set in advance corresponds to a determination threshold value for appropriately determining whether or not the object existing across the detection electrode 11A and the ground electrode 11C is oil. In the present embodiment, the reference voltage corresponds to a DC signal of C [V] as shown in FIG.

  In the present embodiment, the determination unit 14 is configured using a comparator. The reference voltage is input to the non-inverting terminal of the comparator, and the output of the detector 13 is input to the inverting terminal. As shown in FIG. 3, the reference voltage is smaller than A / 2, which is the output of the detector 13 when oil is present across the detection electrode 11A and the ground electrode 11C, and the detection electrode 11A and the ground It is set to be larger than B / 2, which is the output of the detector 13 when air exists over the electrode 11C.

  Thereby, when oil exists over detection electrode 11A and ground electrode 11C, judgment part 14 outputs a high signal, and when air or water exists over detection electrode 11A and ground electrode 11C The determination unit 14 can be configured to output a low signal. Therefore, according to the present sensor 1, it is possible to appropriately detect whether or not the storage level of the oil stored in the container 2 has reached the position of the detection unit 11. That is, according to the present sensor 1, only the oil storage level can be detected.

  Here, the reference voltage described above may be set by the setting unit 15 when the sensor 1 is installed in the container 2. That is, the setting unit 15 sets the amplitude value of the second signal so that the potential of the signal obtained by rectifying the second signal is smaller than the reference voltage when the detection unit 11 is disposed in the part filled with air. Good. Assuming that the setting unit 15 includes an adjustment volume for adjusting the sensitivity, the determination unit 14 in a state where the container 2 is empty (air exists between the detection electrode 11A and the ground electrode 11C). It is better to turn the adjustment volume until a high signal is output from, and turn it in the opposite direction by a minute amount. That is, it is good to return so that a low signal may be output from the determination part 14. At this time, it is preferable that the temperature drift of each functional unit is taken into consideration.

  With such a configuration, it is possible to appropriately detect whether or not the storage level of the oil stored in the container 2 has reached the position of the detection unit 11 using the present sensor 1.

[Other Embodiments]
In the above-described embodiment, the first substance is oil, the second substance is air, and the third substance is water. However, these are merely examples. That is, the second substance is a substance having a dielectric constant smaller than that of the first substance, the third substance has a dielectric constant larger than that of the first substance, and the first substance The first substance, the second substance, and the third substance are the liquids exemplified in the above embodiment as long as the substance has a conductivity higher than that of the second substance and the conductivity of the second substance. It may be a different liquid or a substance other than a liquid (for example, powder).

  In the above embodiment, the signal output unit 12 is described as being configured using an LC oscillator. However, if the signal output unit 12 outputs a signal based on the capacitance of a substance, the signal output unit 12 may be a component other than the LC oscillator. It is also possible to configure by using.

  In the above embodiment, the DC level third signal is indicated by a signal of 0 [V]. However, the DC level signal may have a predetermined potential as long as it is a DC level signal. In the above embodiment, the third signal is described as being a DC level signal. However, the third signal is not limited to a DC level signal, and may be amplified with an amplitude value smaller than the amplitude value of the second signal. Any signal can be used.

  In the above embodiment, when the detection unit 11 is arranged in a part filled with air, the amplitude value of the second signal is set so that the potential of the signal obtained by rectifying the second signal is smaller than the reference voltage. As described above, for example, the setting unit 15 may be configured to set the reference voltage based on the amplitude value of the first signal and the amplitude value of the second signal.

  In the above-described embodiment, the example in which the sensor 1 detects the storage level of the oil stored in the container 2 has been described. However, the substance that circulates in the pipe 6 as shown in FIG. It can also be used to determine whether or not the substance is a certain substance. For example, as in the above embodiment, when the first substance is oil, the second substance is air, and the third substance is water, the oil flows through the pipe 6 by the sensor 1. Can be determined. Therefore, for example, it can be used for an apparatus that issues a warning when oil does not flow through the pipe 6 or when water flows.

  In the above embodiment, the detection unit 11 is described as being configured in a rod shape, but the detection unit 11 may be configured in a circular shape or a flat shape. Of course, other shapes can be used. In any case, the detection electrode 11A and the ground electrode 11C are preferably configured to be insulated by the insulating portion 11B.

  The present invention relates to a first material having a predetermined dielectric constant and conductivity, a second material having a dielectric constant smaller than that of the first material, and a dielectric larger than the dielectric constant of the first material. And a sensor for discriminating between a conductivity of the first substance and a third substance having a conductivity higher than that of the second substance.

1: Sensor 2: Container 11: Detection unit 11A: Detection electrode 11C: Ground electrode 12: Signal output unit 13: Detection unit 14: Determination unit 15: Setting unit

Claims (3)

A first material having a predetermined dielectric constant and conductivity, a second material having a dielectric constant smaller than that of the first material, and a dielectric constant greater than the dielectric constant of the first material. A sensor for discriminating between a conductivity of the first substance and a third substance having a conductivity greater than the conductivity of the second substance,
A detection unit having a detection electrode and a ground electrode insulated from each other;
When the first substance is present across the detection electrode and the ground electrode, a first signal having a predetermined amplitude value is output, and the first signal is output across the detection electrode and the ground electrode. When two substances are present, a second signal having an amplitude value smaller than the amplitude value of the first signal is output, and the third substance is present across the detection electrode and the ground electrode. A signal output unit that outputs a third signal having an amplitude value smaller than the amplitude value of the second signal,
A detector for rectifying the signal output from the signal output unit;
A determination unit that compares the signal rectified by the detection unit with a preset reference voltage to determine whether or not the substance existing across the detection electrode and the ground electrode is the first substance. When,
Comprising a sensor. The signal output unit is configured using an LC oscillator,
The LC oscillator outputs the first signal that oscillates according to the capacitance based on the dielectric constant of the first substance, and oscillates according to the capacitance based on the dielectric constant of the second substance. The sensor according to claim 1, wherein the sensor is configured to output a second signal and output the third signal according to conductivity of the third substance.   The amplitude value of the second signal is set so that the potential of the signal obtained by rectifying the second signal is smaller than the reference voltage when the detection unit is disposed in the portion filled with the third substance. The sensor according to claim 1, further comprising a setting unit that performs the setting.

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