JP2011069802A - Flow detector and detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow detector and a flow detecting system capable of detecting a flow rate of an exhaust gas with a simple constitution. <P>SOLUTION: The flow detector includes a temperature sensor 31 detecting a temperature of the exhaust gas atmosphere, a first operator 41 computing a first value indicating variation per unit time of the temperature of the exhaust gas atmosphere, a heating element 32 generating heat, a heating element controller 42 controlling temperature of the heating element 32 so as to hold temperature of the heating element 32 at a predetermined constant temperature, a second operator 43 computing a second value containing variation of temperature per unit time of the exhaust gas atmosphere and flow rate the exhaust gas moves through an exhaust passage P per unit time, based on the value of electric power supplied to the heating element 32 from a heating element controller 42, and a flow rate computer 44 computing a flow rate of exhaust gas indicating how many exhaust gas moves through the exhaust passage per unit time by taking a different of the first value from the second value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flow rate detection device and a detection system for detecting a flow rate of exhaust gas moving in an exhaust passage.

  As a flow rate detection device that detects the flow rate of exhaust gas from an internal combustion engine, for example, a flow rate detection device using a thermal flow rate method is known (see, for example, Patent Documents 1 to 4).

  Such a flow rate detection device detects the flow rate of exhaust gas by the following method, for example. That is, this flow rate detecting device includes two heat generating elements in the exhaust passage, and detects the flow rate of the exhaust gas of the internal combustion engine by always keeping the temperature difference (ΔT) between the two heat generating elements constant.

JP 2006-317295 A JP 2008-170158 A JP 2008-190999 A JP 2008-292330 A

  However, in the flow rate detection device using the thermal flow rate method described above, the temperature of the heating element needs to be controlled so as to always maintain the above ΔT, and thus the mechanism for realizing the flow rate detection device is complicated. To do. Specifically, the temperature of the exhaust gas atmosphere constantly changes over time (for example, in seconds). For this reason, the flow rate detection device needs to control the heating element so as to always keep the ΔT constant with respect to the temperature following the change in the temperature of the atmosphere of the exhaust gas.

  The present invention has been made in view of the above-described problems, and an object thereof is related to a flow rate detection device and a detection system that can detect the flow rate of exhaust gas with a simple configuration.

  In order to achieve the above object, a flow rate detection device according to the present invention is a flow rate detection device that detects the flow rate of exhaust gas that moves through an exhaust passage, and is provided in the exhaust passage, and the exhaust gas atmosphere is A temperature sensor that detects the temperature of the exhaust gas, and a first calculation unit that calculates a first value indicating a change amount per unit time of the temperature of the exhaust gas atmosphere based on the temperature detected by the temperature sensor; The heating element is provided in the exhaust passage and generates heat, and power is supplied to the heating element so that the temperature of the heating element is maintained at a predetermined temperature. A heating element control unit for controlling the temperature of the body, and based on the value of the electric power supplied to the heating element by the heating element control unit, the amount of change per unit time of the temperature of the exhaust gas atmosphere, Above A second calculation unit that calculates a second value that includes a flow rate of gas gas that has moved through the exhaust passage per unit time, and the first calculation unit that is calculated from the second value calculated by the second calculation unit. A flow rate calculation unit that calculates a flow rate of the exhaust gas moving through the exhaust passage per unit time by taking a difference between the first values.

  The flow rate detection device and the detection system of the present invention have an effect that the flow rate of exhaust gas can be detected with a simple configuration.

FIG. 1 is a block diagram showing a schematic configuration of a detection system according to the present embodiment. FIG. 2 is a perspective view showing a schematic configuration of the flow sensor according to the present embodiment. 3 is a cross-sectional view taken along the cutting line II shown in FIG. FIG. 4A is a cross-sectional view taken along the cutting line II-II shown in FIG. FIG. 4B is a development view in which the flow rate sensor is developed. FIG. 5 is a cross-sectional view showing a schematic configuration of the flow sensor when a hollow portion is formed inside the insulator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a detection system 1 according to the present embodiment. As shown in FIG. 1, a detection system 1 according to this embodiment is provided in a combustion apparatus that uses petroleum fuel such as a vehicle (automobile or the like) (not shown), and includes a filter device 2, a flow sensor. 3, a flow rate calculation device 4, a deposition amount detection sensor 5, a deposition amount calculation device 6, an ECU (Electronic Control Unit) 7, and a control device 8. Here, the flow rate sensor 3 and the flow rate calculation device 4 are an embodiment of the flow rate detection device according to the present invention.

  The filter device 2 is provided in the exhaust passage P and is a device for collecting particulate matter (PM) contained in the exhaust gas moving through the exhaust passage P. The filter device 2 is composed of, for example, a DPF (Diesel Particulate Filter). That is, the exhaust gas is generated when an internal combustion engine such as a diesel engine, a piston engine, a gas turbine engine, or the like burns, and as indicated by an arrow in FIG. Move P. The exhaust gas that has passed through the silencer is released to the outside. Here, as the particulate matter contained in the exhaust gas, for example, simple solid carbon fine particles linked in tufts, a polymer hydrocarbon called SOF (Soluble Organic Fraction), or sulfates are included. Can be mentioned. Since the particulate matter is deposited in the human respiratory tract and lungs, it can adversely affect the human body and cause air pollution. Therefore, the particulate matter is collected in the filter device 2.

  The flow rate sensor 3 is a sensor for detecting the flow rate of the exhaust gas moving through the exhaust passage P, and is provided in the exhaust passage P upstream of the filter device 2 (internal combustion engine side).

  FIG. 2 is a perspective view showing a schematic configuration of the flow sensor 3 according to the present embodiment. 3 is a cross-sectional view taken along the cutting line II shown in FIG. FIG. 4A is a cross-sectional view taken along the cutting line II-II shown in FIG. FIG. 4B is a development view in which the flow sensor 3 is developed.

  As shown in FIG. 2, the flow sensor 3 according to the present embodiment has a round bar shape as viewed from the outside, and is provided on a base B provided in the exhaust passage P. The flow sensor 3 may be provided directly in the exhaust passage P without providing the base B. In addition, the flow sensor 3 according to the present embodiment has a round bar shape in appearance, but is not limited thereto, and may be a rectangular parallelepiped shape, a plate shape, or the like, and the shape is not particularly limited. However, it is preferable to form the flow sensor 3 in a round bar shape as in the present embodiment because the exhaust gas moving in the exhaust passage P can be prevented from being obstructed by the flow sensor 3.

  Here, the flow sensor 3 includes a first temperature sensor 31, a heating element 32, and a second temperature sensor 33.

  As shown in FIG. 3, the first temperature sensor (temperature sensor) 31 is a member that is embedded in the insulator 3 a constituting the flow sensor 3 and plays a role of detecting the temperature of the exhaust gas atmosphere. . Therefore, the first temperature sensor 31 is positioned upstream of the first temperature sensor 31 and opposed to the first temperature sensor 31 so that the first temperature sensor 31 is not affected by the wind of the exhaust gas moving through the exhaust passage P. A wind shield W for the exhaust gas is provided. Since the wind shield W is provided, the first temperature sensor 31 can detect only the temperature of the atmosphere of the exhaust gas without being affected by the wind of the exhaust gas. In FIG. 2, illustration of the windbreak W is omitted for convenience.

  The first temperature sensor 31 is composed of a resistor having a large change in electrical resistance with respect to a change in temperature, such as platinum or tungsten. As the insulator 3a, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or a glass ceramic sintered body is used. And ceramics. That is, a rectangular pattern (see FIG. 4B) to be the first temperature sensor 31 is printed on the insulator 3a, and the insulator 3a on which the rectangular pattern is printed is wound, so that the insulator 3a The first temperature sensor 31 is embedded in the first. Since the 1st temperature sensor 31 is embed | buried under the insulator 3a, it can suppress that the 1st temperature sensor 31 corrodes with exhaust gas.

  As shown in FIG. 3, the heating element 32 is a member that is embedded in the same insulator 3 a as the insulator 3 a in which the first temperature sensor 31 is embedded and plays a role of generating heat. That is, the temperature of the heating element 32 varies depending on the influence of the wind of the exhaust gas moving through the exhaust passage P and the temperature of the exhaust gas atmosphere. For example, if the influence of the exhaust gas wind is weak and the temperature of the exhaust gas atmosphere is high, the heating element 32 is warmed, so the temperature of the heating element 32 becomes high. On the other hand, if the influence of the exhaust gas wind is strong and the temperature of the exhaust gas atmosphere is low, the heating element 32 is cooled, so the temperature of the heating element 32 is lowered.

  Moreover, the heat generating body 32 generates heat according to the amount of supplied electric power by receiving supply of electric power from the heat generating element control unit 42 described later. In the present embodiment, the larger the amount of power supplied to the heating element 32, the larger the amount of heat generation and the higher the temperature. In addition, the smaller the amount of power supplied to the heating element 32, the smaller the amount of heat generated, and the temperature rise is suppressed. Note that the heating element 32 may also serve as the second temperature sensor 33 described later.

  As shown in FIG. 3, the second temperature sensor 33 is embedded in the same insulator 3 a as the insulator 3 a in which the first temperature sensor 31 and the heating element 32 are embedded, and detects the temperature of the heating element 32. It is a member that plays a role. Similar to the first temperature sensor 31, the second temperature sensor 33 is composed of a resistor having a large change in electrical resistance with respect to a temperature change, such as platinum or tungsten. That is, a linear pattern serving as the heating element 32 is printed on the insulator 3a, and a linear pattern serving as the second temperature sensor 33 is printed in the vicinity and inside of this pattern (FIG. 4B). reference). By doing in this way, the 2nd temperature sensor 33 can detect the temperature of the heat generating body 32 correctly. And the heat generating body 32 and the 2nd temperature sensor 33 are embed | buried under the insulator 3a by winding the insulator 3a with which the linear pattern was printed. Since the heat generating body 32 and the second temperature sensor 33 are embedded in the insulator 3a, the heat generating body 32 and the second temperature sensor 33 can be prevented from being corroded by the exhaust gas.

  In addition, the linear pattern used as the heat generating body 32 and the linear pattern used as the 2nd temperature sensor 33 are not restricted to the pattern shown in FIG.4 (b). That is, any pattern may be used as long as it can sufficiently perform the function as the heating element 32 and the function as the second temperature sensor 33.

  Incidentally, since the first temperature sensor 31 detects only the temperature of the atmosphere of the exhaust gas, it is necessary to prevent the heat generated from the heating element 32 from being transmitted to the first temperature sensor 31. For this reason, in this embodiment, the notch part C as a heat insulation part is formed in the insulator 3a between the 1st temperature sensor 31 and the heat generating body 32. As shown in FIG. Since the notch C is formed, the heat generated from the heating element 32 is blocked by the notch C. Therefore, it is possible to suppress the heat generated from the heating element 32 from being transmitted to the first temperature sensor 31. In FIGS. 2 and 3, the example in which the notch C is formed in one place in the insulator 3 a is illustrated, but the present invention is not limited to this. For example, a plurality of notches C may be formed in the insulator 3a.

Further, as shown in FIG. 5, in addition to forming the notch portion C in the insulator 3a, a hollow portion S is formed in the insulator 3a between the first temperature sensor 31 and the heating element 32. Also good. In the following description, when describing the hollow portion S, only when it is necessary to particularly distinguish, for example, the first hollow portion S ₁ is described with a small number for distinguishing each, When it is not necessary to distinguish between them or when they are collectively referred to, for example, a hollow portion S will be described without adding a small number.

Specifically, the flow sensor 3 shown in FIG. 5 includes, in addition to the notch portion C, a first hollow portion S ₁ formed inside the insulator 3 a between the notch portion C and the first temperature sensor 31. , and a second hollow portion S ₂ formed in the insulating body 3a between the notch C and the heating element 32. Here, the first hollow portion S ₁ and the second pressure of the hollow portion S _2, lower than the external pressure. That is, in this embodiment, since the insulator 3a is a ceramic, the pressure of the hollow portion S becomes lower than the external pressure by firing at the time of manufacturing the insulator 3a.

In this way, in addition to forming the notch portion C in the insulator 3a, if the hollow portion S is formed inside the insulator 3a, the heat generated from the heating element 32 is transferred to the second hollow portion S ₂ , the notch part C, and it will be blocked by the first order of the hollow portion S _1. That is, since the air pressure in the hollow portion S is lower than the external air pressure, the heat generated from the heating element 32 is blocked by the hollow portion S. In order to further enhance this blocking effect, the hollow portion S is preferably in a vacuum state.

In the above, in addition to forming the notch C in the insulating body 3a, an example has been described of forming a first hollow portion S ₁ and the second hollow portion S ₂ in the insulating body 3a, to It is not limited. That is, without forming the cutout portions C in the insulating body 3a, formed within only the first hollow portion S ₁ and the second hollow portion S ₂ of the insulator 3a between the first temperature sensor 31 and the heating element 32 May be. It is also possible to form any one of the first hollow portion S ₁ and the second hollow portion S _2. Furthermore, in addition to the first hollow portion S ₁ and the second hollow portion S _2, it may be formed other hollow section.

  In addition, although the 1st temperature sensor 31, the heat generating body 32, and the 2nd temperature sensor 33 demonstrated the example embed | buried under the same insulator 3a above, it is not limited to this. That is, the insulator in which the first temperature sensor 31 is embedded and the insulator in which the heating element 32 and the second temperature sensor 33 are embedded may be separate. In this case, it is not necessary to provide the insulator with the cutout portion C and the hollow portion S as heat insulation portions. Here, as in the present embodiment, if the first temperature sensor 31, the heating element 32, and the second temperature sensor 33 are embedded in the same insulator 3a (that is, if they are formed as an integral structure). The member does not increase, which is preferable.

  In the above description, as shown in FIG. 4B, a linear pattern to be the heating element 32 is printed on the insulator 3a, and the second temperature sensor 33 is formed in the vicinity of and inside the pattern. Although the example which prints a linear pattern was demonstrated, it is not limited to this. In other words, the linear pattern serving as the second temperature sensor 33 may be printed on the surface opposite to the surface on which the linear pattern serving as the heating element 32 is printed. The rectangular pattern that becomes the first temperature sensor 31 is printed on the insulator 3 a so as to be opposed to the linear pattern that becomes the heating element 32 through the hollow formed in the insulator 31. It may be. In other words, if the heat generated from the heating element 32 is not transmitted to the first temperature sensor 31, the formation positions of the first temperature sensor 31, the heating element 32, and the second temperature sensor 33 are arbitrary.

  The flow rate calculation device 4 includes a first calculation unit 41, a heating element control unit 42, a second calculation unit 43, and a flow rate calculation unit 44. Here, the functions of the first calculation unit 41, the heating element control unit 42, the second calculation unit 43, and the flow rate calculation unit 44 described above are executed by a calculation device such as a CPU provided in the flow rate calculation device 4 by a predetermined program. It is realized by doing. Therefore, a program for realizing the above functions by the flow rate calculation device 4 or a recording medium on which the program is recorded is also an embodiment of the present invention.

  Based on the temperature detected by the first temperature sensor 31, the first calculator 41 calculates a first value indicating the amount of change per unit time of the temperature of the exhaust gas atmosphere. This first value is a value that is not affected by the wind of the exhaust gas. The first calculation unit 41 outputs the calculated first value to the flow rate calculation unit 44.

  The heating element control unit 42 controls the temperature of the heating element 32 by supplying power to the heating element 32 so that the temperature of the heating element 32 is maintained at a predetermined constant temperature.

  Specifically, the heating element control unit 42 first acquires the temperature detected by the second temperature sensor 33 from the second temperature sensor 33. Thereby, the heating element control unit 42 can detect the temperature of the heating element 32. The heating element control unit 42 supplies power to the heating element 32 so that the temperature of the heating element 32 maintains a predetermined constant temperature (for example, 1000 ° C.). To control.

  For example, if the influence of the exhaust gas wind is weak and the temperature of the exhaust gas atmosphere is high, the heating element 32 is warmed, so the temperature of the heating element 32 is equal to or higher than a predetermined temperature. In this case, the heating element control unit 42 supplies a smaller amount of power to the heating element 32 than usual. Thereby, the heat generating body 32 suppresses generation | occurrence | production of a heat | fever so that it may become predetermined temperature. Further, for example, if the influence of the exhaust gas wind is strong and the temperature of the exhaust gas atmosphere is low, the heating element 32 is cooled, so the temperature of the heating element 32 is less than a predetermined constant temperature. . In this case, the heating element control unit 42 supplies a larger amount of power than usual to the heating element 32. As a result, the heating element 32 generates heat so as to reach a predetermined temperature.

  The “predetermined temperature” is set in advance in a recording unit (not shown) of the heating element control unit 42. Further, the “predetermined temperature” is preferably a temperature at which the particulate matter is burned out. It is preferable that the predetermined temperature is a temperature at which the particulate matter is burned out, because the particulate matter deposited on the flow rate sensor 3 is burned out, and the sensitivity of the flow rate sensor 3 is improved.

  Based on the value of the electric power supplied to the heating element 32 by the heating element control unit 42, the second calculation unit 43 changes the temperature per unit time of the temperature of the exhaust gas and the exhaust gas per unit time. A second value including the flow rate moved through the exhaust passage P is calculated. This second value is a value affected by the wind of the exhaust gas. That is, the second value cannot separate the amount of change in temperature of the exhaust gas atmosphere per unit time from the flow rate of the exhaust gas moving through the exhaust passage P per unit time, and these values are added together. Value. The second calculation unit 43 outputs the calculated second value to the flow rate calculation unit 44.

  The flow rate calculation unit 44 takes the difference between the first value calculated by the first calculation unit 41 from the second value calculated by the second calculation unit 43, so that the exhaust gas moves through the exhaust passage P per unit time. Calculate the flow rate. That is, as described above, the first value is a value indicating the amount of change per unit time of the temperature of the exhaust gas atmosphere, and the second value is per unit time of the temperature of the exhaust gas atmosphere. This is because it is a value including the amount of change and the flow rate at which the exhaust gas moves through the exhaust passage P per unit time. The flow rate calculation unit 44 outputs the calculated exhaust gas flow rate to the control device 8.

  As described above, according to the flow rate detection device (flow rate sensor 3 and flow rate calculation device 4) according to the present embodiment, the heating element control unit 42 keeps the temperature of the heating element 32 at a predetermined constant temperature. The temperature of the heating element 32 is controlled. For this reason, the flow rate detection device according to the present embodiment needs to control the heating element following the change in temperature of the atmosphere of the exhaust gas, like the flow rate detection device using the conventional thermal flow rate method. Absent. That is, the flow rate detection device according to the present embodiment may control the heating element 32 so that the temperature of the heating element 32 is maintained at a predetermined constant temperature regardless of a change in the temperature of the exhaust gas atmosphere. . Therefore, the flow rate detection device according to the present embodiment can detect the flow rate of the exhaust gas with a simple configuration.

  The accumulation amount detection sensor 5 is a sensor for detecting the accumulation amount of the particulate matter deposited while the particulate matter that could not be collected by the filter device 2 is accumulated. The accumulation amount detection sensor 5 is provided in the exhaust passage P on the downstream side (muffler side) of the filter device 2.

  The accumulation amount calculation device 6 calculates the accumulation amount of the particulate matter accumulated on the accumulation amount detection sensor 5 based on the information detected by the accumulation amount detection sensor 5. The accumulation amount calculation device 6 outputs the calculated accumulation amount of the particulate matter to the control device 8.

  The ECU 7 is a controller that controls an ignition system and a combustion system in the internal combustion engine. For example, the ECU 7 decreases or increases the rotational speed of the internal combustion engine or controls the ignition timing of the internal combustion engine or the like according to an instruction from the control device 8 described later. That is, the ECU 7 can control the number of particulate matter contained in the exhaust gas by controlling the ignition system and the combustion system in the internal combustion engine.

  Based on the flow rate of the exhaust gas calculated by the flow rate calculation device 4 and the deposition amount of the particulate matter calculated by the deposition amount calculation device 6, the control device 8 includes the exhaust gas moved per unit time, An uncollectable amount indicating how much particulate matter that could not be collected by the filter device 2 was included is calculated. The control device 8 instructs the ECU 7 based on the calculated uncollectable amount. For example, the control device 8 instructs the ECU 7 to reduce the number of particulate matter contained in the exhaust gas if the calculated uncollectable amount is equal to or greater than the threshold value. The control device 8 may simply display the calculated uncollectable amount on the display without instructing the ECU 7.

  As described above, the present invention is useful as a flow rate detection device or a detection system that can detect the flow rate of exhaust gas with a simple configuration.

DESCRIPTION OF SYMBOLS 1 Detection system 2 Filter apparatus 3 Flow sensor 3a Insulator 31 1st temperature sensor (temperature sensor)
32 Heating element 4 Flow rate calculation device 41 First calculation unit 42 Heating element control unit 43 Second calculation unit 44 Flow rate calculation unit 5 Accumulation amount detection sensor 6 Accumulation amount calculation device 8 Control device C Notch (heat insulation portion)
S Hollow part (heat insulation part)
S ₁ 1st hollow part (heat insulation part)
S2 _2nd hollow part (heat insulation part)

Claims (7)

A flow rate detection device for detecting a flow rate of exhaust gas moving in an exhaust passage,
A temperature sensor that is provided in the exhaust passage and detects a temperature of the exhaust gas atmosphere;
A first computing unit that calculates a first value indicating a change amount per unit time of the temperature of the exhaust gas atmosphere based on the temperature detected by the temperature sensor;
A heating element provided in the exhaust passage and generating heat;
A heating element controller that controls the temperature of the heating element by supplying electric power to the heating element so that the temperature of the heating element is maintained at a predetermined constant temperature;
Based on the value of electric power supplied to the heating element by the heating element control unit, the amount of change in temperature of the exhaust gas atmosphere per unit time and the exhaust gas moves through the exhaust passage per unit time A second calculator that calculates a second value including the flow rate
A flow rate for calculating a flow rate at which the exhaust gas moves through the exhaust passage per unit time by taking a difference between the first value calculated by the first calculation unit from the second value calculated by the second calculation unit. And a flow rate detecting device. The temperature sensor is embedded in an insulator provided in the exhaust passage,
The heating element is embedded in the same insulator as the insulator in which the temperature sensor is embedded,
2. The heat insulator according to claim 1, wherein the insulator between the temperature sensor and the heating element is provided with a heat insulating portion for preventing heat generated by the heating element from being transmitted to the temperature sensor. Flow rate detection device.   The flow rate detection device according to claim 2, wherein the heat insulating portion is a cutout portion formed by cutting out the insulator. The heat insulating part is a hollow part formed inside the insulator,
The flow rate detection device according to claim 2, wherein a pressure of the hollow portion is lower than an external pressure. The heat insulating part is
A notch formed by notching the insulator;
A first hollow portion formed inside the insulator between the notch and the temperature sensor;
A second hollow portion formed inside the insulator between the notch and the heating element,
The flow rate detection device according to claim 2, wherein the air pressure in the first hollow portion and the second hollow portion is lower than the external air pressure. The flow rate detection device according to any one of claims 1 to 5,
A detection system comprising: a filter device that is provided in the exhaust passage and collects particulate matter contained in the exhaust gas. A particulate matter that could not be collected by the filter device is deposited, and a deposited amount detection sensor for detecting the deposited amount of the deposited particulate matter;
A deposition amount calculation device for calculating a deposition amount of the particulate matter deposited on the deposition amount detection sensor based on information detected by the deposition amount detection sensor;
Based on the flow rate of the exhaust gas detected by the flow rate detection device and the deposition amount of the particulate matter calculated by the deposition amount calculation device, the filter device includes the exhaust gas moved per unit time. The detection system according to claim 6, further comprising a control device that calculates an uncollectable amount indicating how much particulate matter that could not be collected was contained.

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