JP2011237189A - Exhaust smoke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which in a translucent smoke sensor disposed on the passage of engine exhaust, a reduced pressure part whose opening degree is fixed suffers a shortage of the quantity of air taken from the atmosphere into an optical element and a resultant smear of optical faces when the exhaust flow rate is small, while an increased pressure loss invites a deterioration in the fuel consumption of the engine when the exhaust flow rate is great.SOLUTION: The target opening degree of an exhaust throttle valve 102 is determined by comparing the differential pressure between the atmospheric pressure measured with an outside air pressure/intra-pipe exhaust pressure sensor 107 and the exhaust pressure near the exhaust throttle valve 102 with a prescribed value. The opening degree of the exhaust throttle valve 102 is so controlled as to make the opening degree of the exhaust throttle valve 102 measured with a valve opening degree sensor 103 equal to the target opening degree thereby to restrain the smear and overheating of optical faces of a light emitting element 105 and a light receiving element 106 due to taken air in an air channel and at the same time to restrain the pressure loss of exhaust attributable to the exhaust throttle valve 102, and further to determine the target opening degree of the exhaust throttle valve 102 on the basis of measured temperatures from temperature sensors 108 of the light emitting element and the light receiving element to similarly control the opening degree of the exhaust throttle valve 102.

Description

  The present invention relates to a technology for suppressing dirt and overheating of an optical surface in a light transmission type smoke sensor provided in an exhaust passage of an engine, and particularly to a technology for reducing pressure loss when an exhaust flow rate increases. It is.

  Conventionally, the light transmission type smoke sensor provided in the exhaust passage of the engine may exceed the upper limit of the service temperature of the optical surface due to heat transfer to the optical surface due to exhaust heat in addition to a decrease in detection sensitivity due to contamination of the optical surface. . Therefore, for example, a technique disclosed in Patent Document 1 is known as a conventional technique for performing stable analysis without being affected by contamination and overheating of the optical surface of the smoke sensor. According to Patent Document 1, a pressure reducing portion with a fixed opening along the flow is formed by narrowing the flow path and speeding up the flow in the gas flow path, and the optical surface of the optical system is formed inside the pressure reducing section. And providing air from outside the gas flow path via an optical surface.

JP 2004-264146 A

  However, in the prior art disclosed in Patent Document 1, since the passage area of the pressure reducing portion is fixed, the intake air flow rate becomes insufficient when the exhaust flow rate decreases, and the fuel consumption of the engine increases due to the increase in pressure loss when the exhaust flow rate increases. There was a problem of getting worse.

  The present invention relates to a light-transmitting smoke sensor provided in an exhaust passage of an engine, which can suppress dirt and overheating of an optical surface of an optical system and reduce pressure loss particularly when an exhaust flow rate increases. The purpose is to provide.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A smoke sensor having a light-transmitting light-emitting element and a light-receiving element provided in an exhaust passage of an engine, the exhaust throttle valve for depressurizing the exhaust passage, and installed in the vicinity of the exhaust throttle valve, outside the exhaust passage An air passage for taking the air into the exhaust passage via the optical surfaces of the light emitting element and the light receiving element, an exhaust throttle valve opening degree detecting means for measuring the opening degree of the exhaust throttle valve, and a pressure reduction in the vicinity of the exhaust throttle valve Exhaust pressure detection means for measuring the exhaust pressure, atmospheric pressure detection means for measuring the atmospheric pressure outside the exhaust passage, exhaust throttle valve opening detection means, exhaust pressure detection means, and atmospheric pressure detection means Calculation control means for calculating the measured value of, and controlling the opening of the exhaust throttle valve,
The arithmetic control means determines a target opening of the exhaust throttle valve by comparing a differential pressure, which is a difference between the measured exhaust pressure and atmospheric pressure, with a predetermined value, and further, The opening of the exhaust throttle valve measured by the throttle valve opening detection means is controlled so that the opening degree of the exhaust throttle valve becomes the determined target opening degree, and the optical surface is contaminated by the intake air of the air passage. And overheating and the pressure loss of the exhaust by the exhaust throttle valve.

A smoke sensor having a light-transmitting light emitting element and a light receiving element provided in an exhaust passage of the engine, the exhaust throttle valve for reducing the pressure of the exhaust passage, and being installed in the vicinity of the exhaust throttle valve, An air passage for taking air outside the light passage into the exhaust passage via an optical surface of the light emitting element and the light receiving element, an exhaust throttle valve opening degree detecting means for measuring an opening degree of the exhaust throttle valve, the light emitting element and the light receiving element The optical surface temperature detecting means for measuring the temperature of the optical surface of the light source, and the measured values from the exhaust throttle valve opening degree detecting means are calculated, and the optical surface temperatures of the light emitting element and the light receiving element from the optical surface temperature detecting means Calculation control means for calculating the measured value of, and controlling the opening of the exhaust throttle valve,
The arithmetic control means calculates the target opening A of the exhaust throttle valve by comparing the measured optical surface temperature of the light emitting element with a predetermined value defined in advance, and the optical of the measured light receiving element. The target opening B of the exhaust throttle valve is calculated by comparing the surface temperature with a predetermined value, and the smaller target opening of the target opening A and the target opening B is calculated. The degree of opening of the exhaust throttle valve is controlled so that the opening degree of the exhaust throttle valve measured by the exhaust throttle valve opening degree detection means becomes the selected target opening degree, and the intake of the air passage is taken into account. The optical surface is prevented from being contaminated and overheated by air, and exhaust pressure loss due to the exhaust throttle valve is suppressed.

In the smoke sensor, an exhaust pressure detecting means for measuring a reduced exhaust pressure in the vicinity of the exhaust throttle valve, an atmospheric pressure detecting means for measuring an atmospheric pressure outside the exhaust passage, and an exhaust throttle valve opening degree detecting means Calculating the measured values from the exhaust pressure detecting means and the atmospheric pressure detecting means, calculating the measured values of the optical surface temperatures of the light emitting element and the light receiving element, and controlling the opening of the exhaust throttle valve Means, and
The arithmetic control means calculates a target opening degree C of the exhaust throttle valve by comparing a differential pressure that is a difference between the measured exhaust pressure and an atmospheric pressure with a predetermined value that is defined in advance. The smallest target opening among the target opening A, the target opening B, and the target opening C is selected, and the opening of the exhaust throttle valve measured by the exhaust throttle valve opening detecting means is the selected target. A configuration in which the opening of the exhaust throttle valve is controlled so as to have an opening, so that contamination and overheating of the optical surface due to the air taken in the air passage are suppressed, and pressure loss of exhaust by the exhaust throttle valve is suppressed. To do.

  According to the present invention, it is possible to minimize the excess and deficiency of the intake air flow rate from outside the exhaust passage regardless of the exhaust flow rate, and to suppress the pressure loss due to the decompression portion of the exhaust passage. As a result, contamination and overheating of the optical surface can be suppressed, a decrease in smoke detection sensitivity can be suppressed, and at the same time, deterioration of fuel consumption due to exhaust pressure loss can be suppressed.

It is a figure which shows the whole smoke sensor structure which concerns on embodiment of this invention, and its connection structure. It is a figure which shows the structure around the engine which used the smoke sensor which concerns on this embodiment, and this. It is a flowchart which shows the 1st operation | movement procedure of the smoke sensor which concerns on embodiment of this invention. It is a flowchart which shows the 2nd operation | movement procedure of the smoke sensor which concerns on embodiment of this invention. It is a flowchart which shows the 3rd operation | movement procedure of the smoke sensor which concerns on embodiment of this invention. It is a graph which shows an example of the relationship between the exhaust throttle valve opening degree regarding this embodiment, and the optical surface temperature of a light receiving element or a light emitting element. It is a graph which shows an example of the relationship between the exhaust throttle valve opening degree regarding this embodiment, and a pressure loss. It is a graph which shows the specific example calculated by the relationship with a gauge pressure about the correction | amendment of the exhaust throttle valve opening degree regarding this embodiment. It is a graph which shows the specific example calculated about the correction | amendment of the exhaust throttle valve opening degree regarding this embodiment by relationship with the optical surface temperature of a light receiving element or a light emitting element. It is a figure explaining the method of determining the valve opening degree of the exhaust throttle valve regarding this embodiment based on the request | requirement from the exhaust treatment apparatus and the dirt and overheating of an optical surface.

  A smoke sensor according to an embodiment of the present invention and a peripheral configuration related thereto will be described first with reference to FIGS. 1 and 2. FIG. 2 is a view showing a smoke sensor according to an embodiment of the present invention and a configuration around the engine using the smoke sensor. From the upstream side of the engine 19, an air cleaner 17, an air flow sensor 2, an intake throttle valve 28, a turbocharger compressor. 6 (b), intercooler 16, intake pressure and intake temperature sensors 30 (a), (b), throttle 13 for adjusting the intake air amount, intake pressure / intake temperature sensor 14, intake pipes 20 (a), (b ), A fuel injection valve (hereinafter referred to as an injector) 5 is disposed. The throttle 13 is preferably an electronically controlled throttle, and the throttle valve is driven by an electric actuator.

  The exhaust pipe 23 includes an exhaust pressure and exhaust temperature sensor 3, sensors 21 (a) and (b) for measuring pressures and temperatures before and after the exhaust purification device 7, and a smoke sensor 27 provided with an exhaust throttle valve. The exhaust gas recirculation gas passages 9 and 26 for recirculating the exhaust gas to the intake pipes 20 (a) and (b) are disposed in the exhaust gas recirculation gas heat exchangers 10 and 31 and the exhaust gas recirculation. Circulating gas flow control valves 11 and 29 are installed.

  The intake air amount control means related to the present embodiment includes an intake throttle valve 28, a smoke sensor 27 provided with an exhaust throttle valve, exhaust gas recirculation gas flow control valves 11 and 29, a compressor 6 (b), an intercooler 16, a throttle. 13, the intake air amount detection means includes an air flow sensor 2, intake air pressure and intake air temperature sensors 30 (a) and (b), and intake air pressure and intake air temperature sensor 14. In the configuration shown in FIG. 2, the exhaust gas recirculation gas pressure and temperature sensor 12, the exhaust pressure and exhaust temperature sensor 3, and the air flow sensor 2 are used when measuring the exhaust gas recirculation gas flow rate.

  The injector 5 is of a type in which fuel is directly injected into the combustion chamber 18. A predetermined amount of fuel is injected from the injector 5 in accordance with a target engine torque calculated from the opening degree signal α of the accelerator opening degree sensor 1, and the fuel amount is determined based on the opening degree signal θtp of the throttle 13, the exhaust gas recycle. Correction is appropriately made according to the opening signal θegr of the circulating gas flow control valve 11, the output value of the supercharging pressure Ptin of the compressor 6 (b), and the like. The engine control unit (hereinafter referred to as ECU) 8 determines the combustion mode of the engine 19 according to the engine opening conditions α, the user request such as the brake state, the vehicle state such as the vehicle speed, the engine cooling water temperature and the exhaust gas temperature. The control amount is determined.

  Next, a configuration example of the smoke sensor 27 provided with the exhaust throttle valve shown in FIG. 2 will be described below with reference to FIG. Here, the smoke sensor 27 does not refer only to the light emitting element 105, the optical passage 104, and the light receiving element 106 shown in FIG. 1, but the exhaust throttle valve 102, the valve opening degree detecting means of the exhaust throttle valve 102, and the exhaust throttle. Exhaust pressure detecting means 107 in the vicinity of the valve 102, atmospheric pressure detecting means 107, temperature detecting means 108 for the optical surfaces of the light emitting element and the light receiving element, an intake air passage for taking external air into the exhaust passage via the optical surface, and various detecting means The control unit means a group of components such as a calculation control means for calculating the measured value from the above and controlling the valve opening of the exhaust throttle valve. That is, the smoke sensor 27 is defined as a group of configurations related to the light emitting / receiving elements.

  The exhaust throttle valve 102 is driven by a valve opening sensor 103 provided with a motor. An optical passage 104 is provided in the vicinity of the exhaust throttle valve 102 provided in the exhaust pipe 101, and a light emitting element 105 and a light receiving element 106 are disposed at both ends. That is, the optical passage 104 is configured to cross the exhaust passage of the exhaust pipe 101. Light emitted from the light emitting element 105 passes through the optical path 104, passes through the exhaust, and is sent to the light receiving element 106. The amount of light received sent to the light receiving element 106 changes according to the exhaust concentration. The light receiving element 106 outputs the exhaust concentration to the outside by changing the output voltage according to the amount of received light.

  A gap is provided between the light emitting element 105 and the light receiving element 106, and outside air is taken in via the gap, the optical surface, and the optical passage 104 by pressure reduction by the exhaust throttle valve 102 (not shown). Temperature sensors 108 (a) and (b) are provided in the vicinity of the optical surfaces of the light emitting element 105 and the light receiving element 106, and are used for measuring the temperature of the light emitting element 105 and the light receiving element 106. An external air pressure and an exhaust pipe internal pressure sensor 107 are provided in the vicinity of the optical passage 104 of the exhaust pipe 101 (consisting of two detectors for measuring the external air pressure and the internal pressure, respectively). It is used (the direction of ventilation is determined by comparing the external pressure and the internal pressure). Note that a photo reflector or a photo interrupter may be used instead of the light emitting element 105 and the light receiving element 106.

  Next, a first operation procedure of the smoke sensor according to the embodiment of the present invention will be described below with reference to the flowchart shown in FIG. The operation of the smoke sensor shown in the figure repeats measurement, calculation and control output periodically.

  First, the atmospheric pressure is detected by the external air pressure and the exhaust pipe internal pressure sensor 107 attached to the exhaust pipe 101 (block 1001). Next, the exhaust pressure is detected by the external pressure and the exhaust pipe internal pressure sensor 107 attached to the exhaust pipe 101 (block 1002). Then, the difference between the pressures measured in the block 1001 and the block 1002 is calculated as the exhaust gauge pressure (exhaust pressure-atmospheric pressure) (block 1004).

  Next, the exhaust gauge pressure calculated in block 1004 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1005). Further, the opening degree of the exhaust throttle valve 102 is detected by a valve opening degree sensor 103 provided with a motor (block 1003).

  Subsequently, the target opening of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1005 to the opening of the exhaust throttle valve 102 detected in block 1003 (block). 1006). Next, the valve opening sensor 103 provided with a motor is driven so that the opening of the exhaust throttle valve 102 becomes the target opening calculated in block 1006 (block 1007). By executing such a procedure, exhaust smoke can be detected without excessive pressure loss due to the exhaust throttle valve 102. In other words, for example, if the exhaust throttle valve 102 is throttled (the throttle mode of the passage is not fixed but variable) and the pressure loss is increased, the pressure in the pipe at the smoke sensor installation location is reduced and the amount of intake air from the outside air As a result, the contamination of the optical surface and overheating can be suppressed. Note that the amount of exhaust gas and the amount of outside air that passes through is a large amount of exhaust gas that can almost ignore the outside air amount, and therefore does not affect the exhaust concentration detection function as a smoke sensor.

  Next, the second operation procedure of the smoke sensor according to the embodiment of the present invention will be described below with reference to the flowchart shown in FIG. The operation of the smoke sensor shown in the figure repeats measurement, calculation and control output periodically.

  First, the opening degree of the exhaust throttle valve 102 is detected by the valve opening degree sensor 103 provided with a motor (block 1104). Further, the optical surface temperature of the light emitting element 105 is detected by the temperature sensor 108 (a) attached to the optical path 104 (block 1101). Next, the optical surface temperature of the light emitting element 105 calculated in block 1101 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1102). Subsequently, the target opening A of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1102 to the opening of the exhaust throttle valve 102 detected in block 1104 ( Block 1103).

  Next, the optical surface temperature of the light receiving element 106 is detected by the temperature sensor 108 (b) attached to the optical path 104 (block 1105). Further, the optical surface temperature of the light receiving element 105 calculated in the block 1105 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1106). Subsequently, the target opening B of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1106 to the opening of the exhaust throttle valve 102 detected in block 1104 ( Block 1107).

  Next, the target opening A of the exhaust throttle valve 102 calculated in block 1103 is compared with the target opening B of the exhaust throttle valve 102 calculated in block 1107, and the smaller one (the one that further throttles the target valve opening) is targeted. An opening is selected (block 1108). The reason for selecting the smaller one is that when the valve opening is further narrowed to increase the intake air volume and lower the temperature of the optical surface, it is necessary to lower the temperature of the optical surface among the light emitting element and the light receiving element. One element is to be selected (the safe side is selected to avoid an increase in the optical surface temperature of either element).

  Next, the valve opening degree sensor 103 provided with a motor is driven so that the opening degree of the exhaust throttle valve 102 becomes the target opening degree selected in the block 1008 (block 1009). In this way, the exhaust pressure is lowered by lowering the exhaust throttle valve 102 to increase the amount of intake from the atmosphere to lower the optical surface temperature. At that time, the exhaust throttle valve 102 is adjusted appropriately. The exhaust smoke concentration can be detected without excessive pressure loss due to the exhaust throttle valve 102 (instead of a fixed throttle).

  Next, a third operation procedure of the smoke sensor according to the embodiment of the present invention will be described below with reference to the flowchart shown in FIG. The operation of the smoke sensor shown in the figure repeats measurement, calculation and control output periodically.

  First, the opening degree of the exhaust throttle valve 102 is detected by the valve opening degree sensor 103 provided with a motor (block 1204). Next, the optical surface temperature of the light emitting element 105 is detected by the temperature sensor 108 (a) attached to the optical path 104 (block 1201). Subsequently, the optical surface temperature of the light emitting element 105 calculated in block 1201 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1202). Then, the target opening A of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1202 to the opening of the exhaust throttle valve 102 detected in block 1204 (block). 1203).

  Next, the optical surface temperature of the light receiving element 106 is detected by the temperature sensor 108 (b) attached to the optical path 104 (block 1205). Then, the optical surface temperature of the light receiving element 105 calculated in the block 1205 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1206). Subsequently, the target opening B of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1206 to the opening of the exhaust throttle valve 102 detected in block 1204 ( Block 1207).

  Further, the atmospheric pressure is detected by the external pressure and the exhaust pipe internal pressure sensor 107 attached to the exhaust pipe 101 (block 1212). Then, the exhaust pressure is detected by the external air pressure and the exhaust pipe internal pressure sensor 107 attached to the exhaust pipe 101 (block 1208). Subsequently, the difference in pressure measured in block 1212 and block 1208 is calculated as the exhaust gauge pressure (exhaust pressure-atmospheric pressure) (block 1209). Further, the exhaust gauge pressure calculated in block 1209 is compared with a predetermined value to calculate the excess or deficiency of the exhaust throttle valve 102 opening (block 1210). Subsequently, the target opening C of the exhaust throttle valve 102 is calculated by adding the excess or deficiency of the exhaust throttle valve 102 calculated in block 1210 to the opening of the exhaust throttle valve 102 detected in block 1204 ( Block 1211).

  Next, the target opening A of the exhaust throttle valve 102 calculated in block 1203 is compared with the target opening B of the exhaust throttle valve 102 calculated in block 1207 and the target opening C of the exhaust throttle valve 102 calculated in block 1211. The smaller one is selected as the target opening (block 1213). By selecting the smaller target valve opening, the safety side is selected so as to prevent the optical surface temperature of either the light emitting element or the light receiving element from rising and being damaged.

  Next, the valve opening sensor 103 provided with a motor is driven so that the opening of the exhaust throttle valve 102 becomes the target opening selected in block 1213 (block 1214). As described above, the exhaust smoke concentration can be detected without excessive pressure loss caused by the exhaust throttle valve 102, as in the first and second procedures described above.

  Next, as one of the features of the smoke sensor according to the present embodiment, the fuel loss of the engine deteriorates due to an increase in pressure loss in the exhaust passage due to the throttle valve (the amount of intake air to the engine by restricting the exhaust passage) Will be described below with reference to FIGS. 6 and 7. FIG.

  FIG. 6 shows an example of the temperature change of the light receiving element optical surface or the light emitting element optical surface in accordance with the change of the exhaust throttle valve opening in the present embodiment, and FIG. 7 shows the exhaust throttle valve opening in the present embodiment. An example of the relationship with the pressure loss accompanying the change of the exhaust flow rate is shown.

  By reducing the opening of the exhaust throttle valve, the exhaust pressure decreases and the amount of intake air increases, causing the temperature of the light receiving element optical surface or light emitting element optical surface to decrease. At the same time, however, pressure loss increases, resulting in engine output and fuel consumption. The basic performance will be adversely affected. For this reason, it is necessary to increase the opening of the exhaust throttle valve as much as possible within a range in which necessary measurement accuracy can be ensured.

  However, as indicated by reference numeral 2001 in FIG. 7, when the opening of the exhaust throttle valve is fixed (in the case of Patent Document 1, the valve opening P1 in the illustrated example), the necessary pressure reduction is performed even when the exhaust flow rate is small. In order to achieve this, it is necessary to reduce the opening of the exhaust throttle valve, and as the exhaust flow rate increases, a pressure loss more than necessary occurs. The loss is larger than the small exhaust flow). Therefore, the exhaust valve opening is adjusted according to the exhaust flow rate according to reference numeral 2003 in FIG. 7 so that an appropriate pressure loss value indicated by reference numeral 2002 in FIG. It is effective to avoid an increase in pressure loss (deterioration of engine fuel consumption) when P2 and the exhaust flow rate are large.

  FIG. 8 is an example of excess / deficiency calculation of the exhaust throttle valve opening in the block 1005 in the first operating hand shown in FIG. When the gauge pressure (exhaust pressure-atmospheric pressure) is smaller than zero, the outside air is taken into the exhaust pipe due to the pressure difference, and the light emitting element and the light receiving element are considered to be cooled. Make it open more.

  However, in actuality, there are cases where the upper limit temperatures of the light emitting element and the light receiving element are exceeded due to an increase in the exhaust temperature and the outside air temperature. Further, due to the heat capacity of the exhaust smoke sensor itself, there may be a time delay in cooling the light emitting element and the light receiving element. Further, when the instantaneous value of the gas pressure is small in the pulsation of the exhaust gas pressure, the exhaust gas may go out to the atmosphere via the optical surface, that is, a part of the exhaust gas may flow backward to contaminate the optical surface. . Considering these, it is preferable that the opening / closing switching of the exhaust throttle valve is based on a smaller gauge pressure rather than a state where the gauge pressure becomes zero.

  FIG. 9 is an example of excess / deficiency calculation of the exhaust throttle valve opening in block 1106 in the second operation procedure shown in FIG. When the optical surface temperature of the light receiving element or the light emitting element is lower than a predetermined value, it is considered that the light emitting element or the light receiving element has a sufficient heat resistance performance, and the exhaust throttle valve opening is set to be more open.

  However, due to the heat capacity of the exhaust smoke sensor itself, there may be a time delay in cooling the light emitting element and the light receiving element. In consideration of this, it is preferable that the opening / closing switching of the exhaust throttle valve is not based on the upper limit temperature of the light emitting element or the light receiving element, but based on a smaller temperature.

  Note that since the startability is prioritized when the engine is started, the air-fuel ratio becomes dark and the measurement accuracy of the A / F sensor is low. For this reason, exhaust gas increases until a certain time has elapsed from the start of the engine, which increases the possibility of contaminating the optical surface of the exhaust smoke sensor. For this reason, by setting the target opening smaller than the target opening of the exhaust throttle valve described above for a certain period of time after the engine is started, it is possible to increase the amount of intake air and prevent contamination.

  FIG. 10 shows an example of a method for determining the valve opening degree of the exhaust throttle valve 102. The exhaust throttle valve is a means for suppressing the contamination and overheating of the optical surface of the optical element as described above (when the engine is started at the initial stage of the horizontal axis shown in FIG. 10, the opening is further smaller than the target opening of the exhaust throttle valve. In this way, the intake air amount is increased to suppress dirt and overheating, which is applied to increase the efficiency of the exhaust treatment device (for example, catalyst) 7 shown in FIG. (The opening of the exhaust throttle valve 102 is increased when the engine is started at the initial stage of the horizontal axis shown in FIG. 10 to smooth the flow of exhaust gas through the catalyst and reduce the exhaust noise. Dash-dot line 3001) shown. In this way, from the viewpoint of contamination and overheating of the optical surface, catalyst efficiency, and exhaust noise reduction, when the respective valve opening requirement values for the exhaust throttle valve are different, the smallest value can be applied in anticipation of the safety side. Necessary (solid line 3003 shown in FIG. 10).

1: accelerator opening sensor, 2: intake air flow sensor, 3: exhaust pressure and exhaust temperature sensor, 5: injector, 6 (a): compressor, 6 (b): turbine, 7: exhaust treatment device, 8: ECU , 9: exhaust gas recirculation gas passage A, 10: heat exchanger, 11: exhaust gas recirculation gas flow control valve, 12: exhaust gas recirculation gas pressure and temperature sensor, 13: throttle, 14: intake pressure sensor, 15: Fuel pump, 16: Intercooler, 17: Air cleaner, 18: Combustion chamber, 19: Engine,
20: intake pipe, 21 (a): catalyst diagnostic sensor (upstream side), 21 (b): catalyst diagnostic sensor (downstream side), 22: fuel pipe, 23: exhaust pipe, 24: intake air flow rate, 25 : Exhaust gas recirculation gas flow rate, 26: exhaust gas recirculation gas passage B, 27: exhaust throttle valve and exhaust smoke sensor, 28: intake throttle valve, 29: exhaust gas recirculation gas flow control valve, 30: intake pressure and Intake temperature sensor, 31: exhaust gas recirculation gas heat exchanger,
101: exhaust pipe, 102: exhaust throttle valve, 103: motor and valve opening sensor, 104: optical passage, 105: light emitting element, 106: light receiving element, 107: external pressure and exhaust pipe internal pressure sensor, 108: temperature sensor

Claims (4)

A smoke sensor having a light-transmitting light emitting element and a light receiving element provided in an exhaust passage of an engine,
An exhaust throttle valve for depressurizing the exhaust passage;
An air passage installed in the vicinity of the exhaust throttle valve and taking air outside the exhaust passage into the exhaust passage via an optical surface of the light emitting element and the light receiving element;
Exhaust throttle valve opening degree detecting means for measuring the opening degree of the exhaust throttle valve;
An exhaust pressure detecting means for measuring a reduced exhaust pressure in the vicinity of the exhaust throttle valve;
Atmospheric pressure detection means for measuring the atmospheric pressure outside the exhaust passage;
Calculation control means for calculating a measured value from the exhaust throttle valve opening detection means, the exhaust pressure detection means, and the atmospheric pressure detection means, and controlling the opening of the exhaust throttle valve;
The arithmetic control means determines a target opening of the exhaust throttle valve by comparing a differential pressure, which is a difference between the measured exhaust pressure and atmospheric pressure, with a predetermined value, and further, The opening of the exhaust throttle valve measured by the throttle valve opening detection means is controlled so that the opening degree of the exhaust throttle valve becomes the determined target opening degree, and the optical surface is contaminated by the intake air of the air passage. A smoke sensor that suppresses overheating and suppresses exhaust pressure loss due to the exhaust throttle valve. A smoke sensor having a light-transmitting light emitting element and a light receiving element provided in an exhaust passage of an engine,
An exhaust throttle valve for depressurizing the exhaust passage;
An air passage installed in the vicinity of the exhaust throttle valve and taking air outside the exhaust passage into the exhaust passage via an optical surface of the light emitting element and the light receiving element;
Exhaust throttle valve opening degree detecting means for measuring the opening degree of the exhaust throttle valve;
Optical surface temperature detecting means for measuring the temperature of the optical surface of the light emitting element and the light receiving element;
Calculate the measured value from the exhaust throttle valve opening detecting means, calculate the measured optical surface temperature of the light emitting element and the light receiving element from the optical surface temperature detecting means, and calculate the opening of the exhaust throttle valve. Arithmetic control means for controlling,
The arithmetic control means calculates the target opening A of the exhaust throttle valve by comparing the measured optical surface temperature of the light emitting element with a predetermined value defined in advance, and the optical of the measured light receiving element. The target opening B of the exhaust throttle valve is calculated by comparing the surface temperature with a predetermined value, and the smaller target opening of the target opening A and the target opening B is calculated. The degree of opening of the exhaust throttle valve is controlled so that the opening degree of the exhaust throttle valve measured by the exhaust throttle valve opening degree detection means becomes the selected target opening degree, and the intake of the air passage is taken into account. A smoke sensor that suppresses contamination and overheating of the optical surface by air and suppresses pressure loss of exhaust gas by the exhaust throttle valve. In claim 2,
An exhaust pressure detecting means for measuring a reduced exhaust pressure in the vicinity of the exhaust throttle valve;
Atmospheric pressure detection means for measuring the atmospheric pressure outside the exhaust passage;
The exhaust throttle valve opening degree detection means, the exhaust pressure detection means, and the atmospheric pressure detection means are calculated, and the measured values of the optical surface temperatures of the light emitting element and the light receiving element are calculated. And an arithmetic control means for controlling the opening degree of
The arithmetic control means calculates a target opening degree C of the exhaust throttle valve by comparing a differential pressure that is a difference between the measured exhaust pressure and an atmospheric pressure with a predetermined value that is defined in advance. The smallest target opening among the target opening A, the target opening B, and the target opening C is selected, and the opening of the exhaust throttle valve measured by the exhaust throttle valve opening detecting means is the selected target. The opening of the exhaust throttle valve is controlled so that the opening becomes the same, and the contamination and overheating of the optical surface due to the air taken in the air passage are suppressed, and the pressure loss of the exhaust due to the exhaust throttle valve is suppressed. A featured smoke sensor. In claim 1, 2 or 3,
The calculation control means sets the determined target opening or a target opening that is smaller than the selected target opening in a period in which the air-fuel ratio is high from when the engine starts to when a certain time elapses, The opening of the exhaust throttle valve measured by the throttle valve opening detection means is controlled so that the opening of the exhaust throttle valve becomes the set target opening, and the optical surface is contaminated by the air taken in the air passage. Smoke sensor characterized by suppressing

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