KR101688197B1 - Apparatus and method for detecting particulate matter using electromagnetic induction - Google Patents

Abstract

[0001] The present invention relates to a sensor for detecting particles such as soot contained in automobile exhaust gas, and more particularly to a flat-plate type electrode contacting with exhaust gas and a magnetic field induction electrode spaced apart to induce an eddy current, And a sensor for measuring the concentration of particles by measuring the power consumption which varies depending on the temperature.

Description

TECHNICAL FIELD [0001] The present invention relates to a particle detection sensor and a measurement method,

[0001] The present invention relates to a sensor for detecting particles such as soot contained in automobile exhaust gas, and more particularly to a flat-plate type electrode contacting with exhaust gas and a magnetic field induction electrode spaced apart to induce an eddy current, And a sensor for measuring the concentration of particles by measuring the power consumption which varies depending on the temperature.

As regulations for automobile exhaust gas are strengthened, attention is increasing to devices for reducing or purifying harmful component emissions. Particularly, particulate matter (PM) among the harmful components has been strictly regulated, and an exhaust gas reduction apparatus for filtering by using an oxidation catalyst, a nitrogen oxide catalyst and a soot filtering apparatus is being developed.

In order to diagnose the failure of the exhaust gas reduction device, a sensor for detecting soot particles is disposed on the downstream side, that is, a flow path through which the exhaust gas passes through the filter.

In the prior art, U.S. Patent Application Publication No. 2009-0126458 discloses a resistance measurement type particle detection sensor. Electrodes spaced apart from each other are formed on the surface of the insulating element. As the particles accumulate between the electrodes, current flows while connecting the electrodes. Since the particles act as resistors, the concentration of the particles is measured using the principle that the resistance gradually decreases and the current increases over time.

Japanese Patent Registration No. 4898902 discloses a capacitance measurement type particle detection sensor. An electrode is disposed inside the insulating element and an external electrode contacting the exhaust gas is disposed. Particles are measured using the principle that the voltage across the electrode varies as the initial voltage applied to both ends of the electrode and the area of the external electrode are accumulated while the particles accumulate between the external electrodes.

However, in the conventional particle detection sensor of the resistance measuring method, when particles having electrical conductivity are attached between the electrodes, signal distortion may occur, and failures may occur due to the particles not being destroyed through the heating process. In addition, the particle detection sensor of the capacitance measurement type also shows a sudden drop in performance when particles are not destroyed by heating, and when particles having electrical conductivity are attached, distortion due to the change in capacitance may occur There was a limit.

There is a growing demand for a particle sensor that overcomes the limitations of conventional measurement methods and has improved durability and reliability of measurement.

It is an object of the present invention to provide a sensor for detecting particles such as soot contained in automobile exhaust gas, comprising a plate-like electrode in contact with an exhaust gas and a magnetic field induction electrode spaced apart to induce an eddy current, And to provide a sensor for measuring the concentration of particles by measuring the power consumption which varies accordingly.

According to an aspect of the present invention, there is provided a current-induced particle detection sensor comprising: an insulating substrate having a pair of opposed surfaces; A planar electrode disposed on one surface of the pair of opposing surfaces and in contact with the exhaust gas; And a magnetic field induction electrode formed on the other of the pair of opposing surfaces or inside the insulating base.

At this time, the magnetic field induction electrode generates an induced magnetic field by applying AC power, and eddy current is generated by the induced magnetic field in the planar electrode.

In this case, the induced magnetic field is calculated according to Equation (1), and the power consumption consumed by the flat plate-shaped electrode due to the eddy current can be calculated by Equation (2).

[Equation 1]

(Wherein, B is the strength of the magnetic field (T), k is 2π · 10 ^{- 7,} a constant (T · m / A), I is the intensity of electric current (A), r is the radius (m) of a circle)

&Quot; (2) "

(Wherein, P is 1, a constant consumption power (W / kg), B _p per unit mass is the maximum field strength (T), d is the thickness (m of the plate-like electrode), f is the frequency (H _z), k , ρ is the resistance (Ω · m) of the flat plate type electrode, and D is the density (kg / m ³ ) of the flat plate type electrode)

At this time, the magnetic field induction electrode and the plate-like electrode are arranged in parallel to each other, the magnetic field induction electrode is electrically connected to the power supply unit, and the plate-like electrode can be electrically connected to the measurement device.

At this time, a heater may be provided at a position spaced more than a distance between the planar electrode and the magnetic field induction electrode or between the planar electrode and the magnetic field induction electrode.

According to another aspect of the present invention, there is provided a particle detection method using a sensor including a flat plate-type electrode and a magnetic field induction electrode disposed parallel to and spaced from each other, the method comprising: exposing the flat plate- ; Generating an induced magnetic field by applying an AC power to the magnetic field induction electrode; Measuring power consumption of the planar electrode due to the induced magnetic field; And measuring a change in the power consumption that varies depending on the accumulation of the particulate matter contained in the exhaust gas.

According to the present invention, in the case of burning particulate matter by heating the heater, even if the electrically conductive particulate matter remains partially in the external electrode exposed to the exhaust gas, the permanent failure of the sensor does not occur.

1 is a perspective view of a current-induced particle detection sensor according to a first embodiment of the present invention.
2 is a cross-sectional view of a current-induced particle detection sensor according to a first embodiment of the present invention.
3 is a plan view of a particle detection sensor of a current induction type according to the first embodiment of the present invention.
4 (a) to 4 (c) are rear views of the current induction type particle detection sensor according to the first embodiment of the present invention.
5 is a sectional view of a current induction type particle detection sensor according to a second embodiment of the present invention.
6 (a) to 6 (d) are cross-sectional views of a current induction type particle detection sensor according to the third to sixth embodiments of the present invention.
7 is a flowchart of a current induction type particle detection method according to an embodiment of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to give average knowledge in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Figs. 1 to 4 are a perspective view, a cross-sectional view (A-A '), a plan view, and a rear view, respectively, of a current induction type particle detection sensor according to a first embodiment of the present invention. A first embodiment of the present invention is an exhaust gas purifier comprising an insulating base (1) having a pair of opposed faces, a flat electrode (2) arranged on one face of the pair of opposed faces and in contact with the exhaust gas, And a magnetic field induction electrode (3).

5 is a cross-sectional view of a current induction type particle detection sensor according to a second embodiment of the present invention. A second embodiment of the present invention is an insulated base 1 having a pair of opposing surfaces, a planar electrode 2 disposed on one surface of the pair of opposing surfaces to be in contact with the exhaust gas, And a magnetic field induction electrode 3 formed thereon.

6 (a) is a cross-sectional view of a current induction type particle detection sensor in connection with a third embodiment of the present invention. A third embodiment of the present invention is an exhaust gas purifying apparatus comprising an insulating base 1 having a pair of opposed faces, a flat electrode 2 disposed on one face of the pair of opposed faces and in contact with the exhaust gas, A magnetic field induction electrode 3 and a heater 4 formed inside the insulative base 1.

6 (b) is a cross-sectional view of a current induction type particle detection sensor according to a fourth embodiment of the present invention. In a fourth embodiment of the present invention, an insulating substrate 1 having a pair of opposing surfaces, a plate-like electrode 2 disposed on one surface of a pair of opposing surfaces and in contact with the exhaust gas, A magnetic field induction electrode 3 formed thereon, and a heater 4 disposed on the other of the pair of opposing surfaces.

6 (c) is a cross-sectional view of a current induction type particle detection sensor according to a fifth embodiment of the present invention. A fifth embodiment of the present invention relates to an insulating substrate 1 having a pair of opposing surfaces, a flat electrode 2 disposed on one surface of a pair of opposing surfaces and in contact with the exhaust gas, And a magnetic field induction electrode 3 disposed between the heater 4 and the plate-like electrode 2 and the heater 4.

FIG. 6 (d) is a cross-sectional view of a current induction type particle detection sensor according to a sixth embodiment of the present invention. FIG. A sixth embodiment of the present invention is a semiconductor device comprising an insulative base body (1) having a pair of opposing faces, a planar electrode (2) arranged on one surface of the pair of opposing faces and in contact with the exhaust gas, And a heater 4 disposed between the magnetic field induction electrode 3 and the plate electrode 2 and the magnetic field induction electrode 3. [

FIG. 7 is a flow chart of a current induction type particle detection method according to an embodiment of the present invention, in which the flat electrode of the current induction type particle detection sensor shown in FIG. 1 is exposed to exhaust gas (S10) The AC power is applied to the magnetic field induction electrode (S20), the power of the plate electrode is measured (S30), and the particulate matter is detected or the concentration is calculated based on the changed electric power.

Hereinafter, an insulating substrate formed in the particle detecting device of the present invention will be described.

The insulating substrate 1 of the present invention means a substrate made of an insulating material having at least one pair of opposed surfaces. It may be made of a material such as silicon carbide, zirconium oxide, titanium dioxide, alumina or silica ceramic, which is a conventional substrate. The shape of the gas is not limited, but a rectangular parallelepiped is assumed for convenience of explanation. In the insulating substrate 1, a plurality of layers may be laminated to form one insulating layer. In addition, it has an area that can face the flow of the exhaust gas and can lay the flat plate-like electrode 2 on one side. The other surface facing the one surface may be formed with the magnetic field induction electrode 3 or the heater 4.

Hereinafter, a flat electrode formed in the particle detecting device of the present invention will be described.

The planar electrode (2) of the present invention means a plate-shaped electrode formed on one surface of an insulating substrate (1) and electrically conductive. The plate-like electrode 2 is disposed on the outer surface of the insulating substrate 1 so as to face the exhaust gas. The plate-type electrode is electrically connected to a measuring device (not shown) for measuring a changed electric power or electrical characteristic.

Although there is no particular limitation on the shape, it may be a rectangular flat plate shape as shown in FIG. 3, may be circular (not shown), and may be replaced with an electrode having another flat surface on which other eddy currents can be formed.

The planar electrode 2 adheres the particulate matter to be measured, and measures the concentration of the particle using a change in the current or a change in the electric current induced. The plate-like electrode 2 is disposed apart from the magnetic field induction electrode 3, and the current I _eddy induced in accordance with the change of the magnetic field circulates in the plate-like electrode 2. In other words, the induced current flowing to configure a closed circuit in the electrode by a magnetic field change in the external eddy currents or eddy current (eddy current, I _eddy) la and, by measuring the power consumption which changes according to the adhesion of the particulate matter in the particulate matter The concentration is measured.

The measurement object may be a power or a voltage. Other physical properties that have electrical properties that vary with the attachment of particulate matter can also be measured. The plate-like electrode 2 is not particularly limited, but is preferably made of a metal material so as to be advantageous in inducing an eddy current.

Hereinafter, the magnetic field induction electrode formed in the particle detector of the present invention will be described.

The magnetic field induction electrode 3 of the present invention means an electrode that is formed on the other surface of at least one pair of opposing surfaces or inside the insulating substrate 1 and is electrically conductive. That is, the magnetic field induction electrode 3 is disposed so as to face the flat electrode 2, and is externally provided so that a magnetic field can be formed. But it may be circularly wired as shown in Fig. 4 (a) and may be coiled as shown in Fig. 4 (b) or Fig. 4 (c). It can be replaced by another shape that can induce a magnetic field to form an eddy current on the plate-like electrode. The magnetic field induction electrode is electrically connected to a power supply unit (not shown) so as to receive an AC power from the outside.

Both ends of the magnetic field induction electrode are provided with a circuit so that electricity flows, and alternating current power having a period is applied. Here, an AC power source is an alternating current or alternating voltage such as a sinusoidal wave, an implementation wave or a pulse wave, and forms a change of the magnetic field B around the magnetic field induction electrode 3 as shown in FIG. It is preferable to be made of a metallic material so that electricity can flow well.

The magnetic field induction electrode 3 can be directly disposed on the insulating layer base 1 as shown in FIG. 4 but can be wound around the concentric circle on the magnetic field inducing layer 30 independent of the insulating layer base 1 . That is, the magnetic field induction electrode 3 is disposed on the magnetic field inducing layer having a pair of opposing surfaces, and one end and the other end can be formed to face each other. One end and the other end are electrically connected to the terminal and receive AC power from the outside.

As shown in Fig. 5, the magnetic field induction electrode 3 can be disposed inside the insulative base 1. When placed inside the insulating base 1, the influence of the outside can be reduced and the reliability of the measured value can be improved.

Hereinafter, the heater formed in the particle detecting apparatus of the present invention will be described.

The heater 4 of the present invention means a heat wire which is formed inside or on the other side of the insulating substrate 1 and generates heat by receiving external power. The heater 4 may be applied with a heat line arrangement disposed in a conventional particulate sensor, and may be supplied with power by other control methods. The heater 4 burns particles adhered to the insulating substrate 1 or the plate-like electrode 2 by heat generation and is called burning. The heater (4) may be constituted by an area layer capable of generating heat by electricity or a heat line having a resistance.

The heater may be disposed inside the insulating base 1 as shown in Fig. 6, or may be disposed outside. And may be disposed between the flat plate-like electrode 2 and the magnetic field induction electrode 3 or may be disposed to face the flat electrode 2 about the magnetic field induction electrode 3.

Hereinafter, a detection method for measuring particles using the current induced particle detection sensor of the present invention will be described.

The current induced particle detection sensor of the present invention first exposes the flat electrode 2 to the exhaust gas (S10). It may be disposed perpendicular to the flow direction of the exhaust gas as shown in FIG. 1 so that the particulate matter PM may adhere to the flat electrode 2 instead of the magnetic field induction electrode 3, or may be parallel to the flow direction of the exhaust gas Or on one side of the flow pipe.

After step S10, AC power is applied to the magnetic field induction electrode 3 (S20). At this time, the applied AC power source is an AC current or an AC voltage having a constant frequency, which can induce the magnetic field (B). The AC power source is a power source having an externally applied period and is a concept distinguished from a DC power source. Since the magnetic field induced in the magnetic field induction electrode 3 can be changed by applying the AC power, the AC power must be applied. It can be replaced with various signals such as sinusoidal wave, square wave, and triangular wave, and it is possible to apply a signal surface that can induce a magnetic field. The magnetic field induced by the AC signal also has a frequency.

For the understanding of the invention, the magnetic field induction electrode 3 is assumed to be a circular conductor as shown in FIG. 4, and in the case of other types of conductors, the magnitude of the magnetic field is also induced in another form. The intensity of the induced magnetic field can be calculated by Equation (1). Since the alternating current is applied to the magnetic field induction electrode 3, the induced magnetic field is also generated by the alternating current signal.

[Equation 1]

Here, B is the magnetic field (T), k is 2π · 10 ^{- 7} and the constant (T · m / A), I is the intensity (A) of current, r is a radius (m) of the circle.

After step S20, the power consumption of the plate-like electrode 2 is measured (S30). The magnetic field induced in the flat plate-like electrode 2 and the magnetic field induction electrode 3 are perpendicular to each other, forming a closed loop in the inside of the plate-like electrode 2, and an eddy current through which a current flows is formed. An eddy current is generated in the flat plate-like electrode 2 due to the induced magnetic field, and power consumption occurs in the flat plate-like electrode 2. At this time, the consumed power can be calculated by the following equation (2).

&Quot; (2) "

Where p is the power consumption per unit mass (W / kg), Bp is the maximum field strength (T), d is the thickness (m) of the plate electrode, f is the frequency in Hz, Ρ is the resistance (Ωm) of the plate-like electrode, and D is the density (kg / m3) of the plate-like electrode.

After step 30, the concentration of particulate matter is measured by measuring the power consumption that varies as the particulate matter is accumulated on the flat electrode 2 (S40). Specifically, as the particulate matter accumulates, the resistance value r increases, and the power consumption of the flat electrode 2 decreases.

Even if the accumulated particulate matter accumulated in the flat plate-like electrode 2 does not disappear due to the burning of the heater, or the electroconductive particles remain and the area of the flat plate-like electrode 2 remains to be increased, So that only an insignificant error occurs. Therefore, the present invention improves the phenomenon that the permanent failure of the sensor occurs when the conductive particles remain, which is a problem of the conventional resistance type measurement method, and that the performance, which is a problem of the capacitance measurement method, is significantly lowered.

In the measuring method of the present invention, AC power is applied to the magnetic field induction electrode (S10) and the electric power of the flat electrode is first measured (S20). Then, the plate electrode is exposed to the exhaust gas (S30) S40).

1: Insulating gas
2: Plate-type electrode
3: magnetic field induction electrode
4: Heater
B: magnetic field
I _eddy : eddy current

Claims (7)

An insulating substrate having a pair of opposing surfaces;
A planar electrode disposed on one surface of the pair of opposing surfaces and in contact with the exhaust gas;
A magnetic field induction electrode formed on the other surface of the pair of opposing surfaces or inside the insulating substrate to generate an eddy current by generating an induction magnetic field by applying an AC power having a period; And
And a measuring device for measuring the power consumption of the flat-plate type electrode,
Wherein the concentration of the particles is measured through a change in the power consumption of the planar electrode caused by the particles in the exhaust gas adhering to the planar electrode. delete The method according to claim 1,
Wherein the induced magnetic field is calculated by Equation (1), and the power consumption consumed by the plate-like electrode by the eddy current is calculated by Equation (2).
[Equation 1]

(Wherein, B is the strength of the magnetic field (T), k is 2π · 10 ^-7, a constant (T · m / A), I is the intensity of electric current (A), r is the radius (m) of a circle)

&Quot; (2) "

(Wherein, P is 1, a constant consumption power (W / kg), B _p per unit mass is the maximum field strength (T), d is the thickness (m of the plate-like electrode), f is the frequency (H _z), k , ρ is the resistance (Ω · m) of the flat plate type electrode, and D is the density (kg / m ³ ) of the flat plate type electrode) The method of claim 3,
Wherein the magnetic induction electrode and the plate-like electrode are disposed in parallel to each other, the magnetic field induction electrode is electrically connected to the power supply unit, and the plate-like electrode is electrically connected to the measurement device. Detection sensor. The method of claim 4,
And a heater formed at a position spaced more than a distance between the planar electrode and the magnetic field induction electrode or from the planar electrode to the magnetic field induction electrode. 1. A particle measuring method using a sensor having a flat plate-like electrode and a magnetic field induction electrode spaced apart from each other in parallel,
Exposing the planar electrode to an exhaust gas;
Generating an induced magnetic field by applying an AC power having a period to the magnetic field induction electrode;
Generating an eddy current in the planar electrode due to the induced magnetic field;
Measuring power consumption of the flat electrode;
Measuring a change in the power consumption that varies with an accumulation of particles contained in the exhaust gas; And
And measuring the concentration of the particles by measuring a change in the power consumption. The method of claim 6,
Wherein the induced magnetic field is calculated by the following equation (1), and the power consumption consumed by the flat plate-shaped electrode is calculated by equation (2).
[Equation 1]

(Wherein, B is the strength of the magnetic field (T), k is 2π · 10 ^{- 7,} a constant (T · m / A), I is the intensity of electric current (A), r is the radius (m) of a circle)

&Quot; (2) "

(Wherein, P is 1, a constant consumption power (W / kg), B _p per unit mass is the maximum field strength (T), d is the thickness (m of the plate-like electrode), f is the frequency (H _z), k , ρ is the resistance (Ω · m) of the flat plate type electrode, and D is the density (kg / m ³ ) of the flat plate type electrode)

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