WO2010125636A1 - Pm sensor, device for sensing amount of pm in exhaust gas, and abnormality sensing device for internal combustion engine - Google Patents

Abstract

Provided are a PM sensor and a device for sensing the amount of PM in exhaust gas, the sensor and the device being capable of detecting the amount of particulate matter.  Also provided is an abnormality sensing device for an internal combustion engine, capable of sensing abnormality of a particulate filter. A PM sensor and a PM amount sensing device are mounted in an exhaust pipe (10) of an internal combustion engine (2).  In the exhaust pipe (10) are arranged an air-fuel ratio sensor (22), a filter (30), and an air-fuel ratio sensor (24) in that order in the direction of flow of exhaust gas.  The filter (30) is a small-sized particulate capturing filter.  An ECU (50) can obtain outputs from the air-fuel ratio sensors (22, 24).  The ECU (50) has a function of calculating a difference ∆I_L between an output I_L1 and an output I_L2.  The ECU (50) can calculate, based on ∆I_L, the amount of particulate matter in exhaust gas currently flowing into the filter (30).

Description

PM sensor, exhaust gas PM amount detection device, internal combustion engine abnormality detection device

The present invention relates to a PM sensor, an exhaust gas PM amount detection device, and an internal combustion engine abnormality detection device.

Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-284644, there is known an internal combustion engine including a particulate filter for filtering particulate matter in exhaust gas. Hereinafter, the particulate matter (PM) is also simply referred to as “particulate” or “PM”.

The conventional internal combustion engine includes a pressure sensor that detects the differential pressure of the filter. When exhaust gas with a large amount of particulates flows into the filter, the amount of particulates in the filter increases accordingly. The differential pressure of the filter also changes following this. Therefore, the particulate matter amount of the exhaust gas can be detected by detecting the differential pressure of the filter.

In addition, configurations of Japanese Patent Application Laid-Open No. 2007-32490 and Japanese Patent Application Laid-Open No. 2008-64621 are known as configurations for detecting the particulate amount.

JP-A-8-284644 JP 2007-32490 A JP 2008-64621 A

With the recent tightening of emission regulations, there is an increasing need for sensors for detecting the amount of particulates. However, on-board PM sensors and PM amount detection devices that can withstand practical use have not yet appeared in the current technical level. There is an urgent need to develop a PM sensor and a PM amount detection device for detecting the particulate amount. Further, when an abnormality occurs in the particulate filter of the internal combustion engine, it is necessary to take measures immediately. Further advancement in the technology for detecting abnormalities in particulate filters is also desired.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a PM sensor capable of detecting the amount of particulate matter and a PM amount detection device for exhaust gas.

Another object of the present invention is to provide an abnormality detection device for an internal combustion engine capable of detecting an abnormality of a particulate filter.

In order to achieve the above object, a first invention is a PM sensor,
An inflow port for extracting and flowing in part of the gas in the exhaust passage of the internal combustion engine;
A filter for filtering particulate matter (PM) in the gas flowing into the inlet;
A heater attached to the filter and capable of changing a temperature of the filter;
An outlet for allowing the gas that has passed through the filter to flow into the exhaust passage;
An oxygen concentration sensor element that is arranged on the outlet side and changes an output according to the oxygen concentration of the gas that has passed through the filter;
It is characterized by providing.

The second invention is the first invention, wherein
An oxygen concentration sensor element that is disposed on the inlet side and changes an output according to an oxygen concentration of a gas flowing into the filter from the inlet is further provided.

The third invention is the second invention, wherein
The oxygen concentration sensor element on the outlet side and the oxygen concentration sensor element on the inlet side are air-fuel ratio sensor elements.

Moreover, 4th invention is set in 3rd invention,
The air-fuel ratio sensor element includes a heater and is heated to a predetermined temperature by the heater during operation,
When the temperature of the air-fuel ratio sensor element is the predetermined temperature, the filter and the air-fuel ratio sensor element are separated from each other so that the filter has a temperature at which particulate matter in the filter is not removed. It is characterized by being.

In order to achieve the above object, a fifth invention is an exhaust gas PM amount detection device,
A filter that is provided in an exhaust passage of an internal combustion engine and filters particulate matter (PM) in exhaust gas flowing through the exhaust passage;
An oxygen concentration sensor element that is disposed downstream of the filter in the exhaust passage and changes an output according to the oxygen concentration of the gas that has passed through the filter;
A heater attached to the filter;
Heating control means for controlling the heater so that the filter is heated until the particulate matter in the filter is removed;
Temperature reduction control means for controlling the heater so that the temperature of the filter is equal to or lower than the temperature at which the particulate matter in the filter is not removed after the control of the heating control means;
Obtaining means for obtaining an output of the oxygen concentration sensor element after the temperature of the filter becomes equal to or lower than the temperature;
Calculation means for calculating the particulate matter amount of the exhaust gas based on the output acquired by the acquisition means;
It is characterized by providing.

The sixth invention is the fifth invention, wherein
The acquisition means acquires the output of the oxygen concentration sensor element when a predetermined time has elapsed after the temperature of the filter becomes equal to or lower than the temperature,
Means for calculating an integrated value of the amount of exhaust gas flowing into the filter by the acquisition timing of the output of the acquisition means after the temperature of the filter becomes equal to or lower than the temperature;
The calculation means calculates the particulate matter amount of the exhaust gas per unit time and per unit volume based on the output acquired by the acquisition means, the predetermined time, and the integrated value. It is characterized by that.

The seventh invention is the fifth or sixth invention, wherein
An oxygen concentration sensor element disposed upstream of the filter in the exhaust passage and capable of changing an output according to an oxygen concentration of exhaust gas flowing into the filter;
The calculating means calculates a particulate matter amount of the exhaust gas based on a difference between an output of the oxygen concentration sensor element upstream of the filter and an output of the oxygen concentration sensor element downstream of the filter; Features.

The eighth invention is the seventh invention, wherein
The oxygen concentration sensor element on the downstream side of the filter and the oxygen concentration sensor element on the upstream side of the filter are air-fuel ratio sensor elements.

The ninth invention is the eighth invention, wherein
The apparatus further comprises calibration means for calibrating an output deviation between the air-fuel ratio sensor on the downstream side of the filter and the air-fuel ratio sensor on the upstream side of the filter.

In order to achieve the above object, a tenth aspect of the invention is an exhaust gas PM amount detection device,
A filter that is provided in an exhaust passage of an internal combustion engine and filters particulate matter (PM) in exhaust gas flowing through the exhaust passage;
A heater attached to the filter;
Temperature reduction control means for controlling the heater so that the temperature of the filter is equal to or lower than a temperature at which particulate matter in the filter is not removed;
The temperature of the filter becomes equal to or higher than the temperature at which the particulate matter in the filter is removed after a lapse of a predetermined period from when the temperature of the filter becomes equal to or lower than the temperature by the control of the temperature reduction control means. Heating control means for controlling the heater;
A power amount detecting means for detecting a power consumption amount consumed by the heater to remove particulate matter in the filter when the control of the heating control means is performed;
Calculation means for calculating a particulate matter amount of the exhaust gas based on the power consumption detected by the power detection means;
It is characterized by providing.

The eleventh aspect of the invention is the tenth aspect of the invention,
The power amount detection means
Determination means for determining whether or not the particulate matter in the filter has been removed after the start of the control of the heating control means;
A power amount calculating means for calculating a power consumption amount of the heater during a period from the start of the control of the heating control means until it is determined that the particulate matter in the filter has been removed;
Means for calculating the power consumption consumed by the heater to remove particulate matter in the filter based on the power consumption calculated by the power consumption calculating means;
It is characterized by including.

The twelfth invention is the eleventh invention, in which
An upstream oxygen concentration sensor that is disposed upstream of the filter in the exhaust passage and changes an output according to an oxygen concentration of a gas flowing into the filter;
A downstream oxygen concentration sensor disposed downstream of the filter in the exhaust passage and changing an output according to an oxygen concentration of a gas flowing out from the filter,
The determination means determines whether or not the particulate matter in the filter has been removed based on the difference between the output of the upstream oxygen concentration sensor and the output of the downstream oxygen concentration sensor. .

A thirteenth aspect of the invention is an abnormality detection device for an internal combustion engine, in order to achieve the above other object,
An oxygen concentration sensor that is arranged downstream of a particulate filter provided in an exhaust passage of an internal combustion engine and changes an output in accordance with an oxygen concentration of a gas flowing out of the particulate filter;
Heating means for heating the particulate filter so as to regenerate the particulate filter;
Detecting means for detecting an abnormality of the particulate filter based on an output of the downstream oxygen concentration sensor after the regeneration of the particulate filter;
It is characterized by providing.

The fourteenth invention is the thirteenth invention, in which
An oxygen concentration sensor disposed upstream of the particulate filter and configured to change an output according to the oxygen concentration of the exhaust gas;
The detection means detects an abnormality of the particulate filter based on a difference between an output of the downstream oxygen concentration sensor and an output of the upstream oxygen concentration sensor.

The fifteenth aspect of the invention is the fourteenth aspect of the invention,
The oxygen concentration sensors respectively disposed upstream and downstream of the particulate filter are air-fuel ratio sensors.

According to the first invention, the oxygen concentration sensor element exhibits a lower oxygen concentration output as the amount of particulates in the filter increases. Based on the output of the oxygen concentration sensor element, it is possible to detect the particulate amount of the gas flowing into the filter. Further, the particulate matter of the filter can be heated and removed by the heater, so that the particulate amount detection can be repeatedly performed.

According to the second invention, the oxygen concentration sensor elements are provided on the upstream side and the downstream side of the filter, respectively. The output difference between these oxygen concentration sensor elements corresponds to the amount of particulates in the filter with high accuracy. Based on the output difference between these oxygen concentration sensor elements, it is possible to detect the particulate amount of the gas flowing into the filter with high accuracy.

According to the third invention, in the first or second invention, the air-fuel ratio sensor element is used as the oxygen concentration sensor element. As a sensor for detecting the oxygen concentration of exhaust gas, an air-fuel ratio sensor has a proven track record. By using the air-fuel ratio sensor element, the particulate quantity of the exhaust gas can be detected with high reliability.

According to the fourth invention, the following effects can be obtained. The air-fuel ratio sensor generally operates in a state where it is heated to a predetermined activation temperature. On the other hand, when the temperature of the filter becomes higher than a specific temperature, the particulates are burned without accumulating in the filter. According to the fourth aspect of the invention, the filter can reliably hold the particulates even while the temperature of the air-fuel ratio sensor is the activation temperature. As a result, the particulate matter amount of the exhaust gas can be detected while the air-fuel ratio sensor is at the activation temperature.

According to the fifth invention, after the filter is heated to a sufficiently high temperature, the heater is controlled such that the temperature of the filter is lowered to a level where particulates can be collected. After this heater control, particulates are collected by the filter, and the output of the oxygen concentration sensor element is acquired. The greater the amount of particulates in the filter, the lower the oxygen concentration of the gas downstream of the filter and the lower the oxygen concentration sensor element output will be. Therefore, the particulate quantity of the inflow gas to the filter can be calculated based on the output of the oxygen concentration sensor element. Thereby, the particulate quantity of exhaust gas can be detected.

According to the sixth aspect of the present invention, the exhaust gas particulate quantity per unit time and per unit volume can be calculated.

According to the seventh invention, the oxygen concentration sensor elements are provided on the upstream side and the downstream side of the filter, respectively. The output difference between these oxygen concentration sensor elements corresponds to the amount of particulates in the filter with high accuracy. Based on the output difference between these oxygen concentration sensor elements, it is possible to detect the particulate amount of the gas flowing into the filter with high accuracy.

According to the eighth aspect of the invention, the air-fuel ratio sensor element is used as the oxygen concentration sensor element. As a sensor for detecting the oxygen concentration of exhaust gas, an air-fuel ratio sensor has a proven track record. By using the air-fuel ratio sensor element, the particulate quantity of the exhaust gas can be detected with high reliability.

According to the ninth aspect, it is possible to calibrate the output deviation between the plurality of air-fuel ratio sensors. Thereby, the particulate quantity detection with higher accuracy can be performed.

According to the tenth aspect, the amount of particulates can be detected. The greater the amount of particulates in the exhaust gas, the greater the amount of particulates collected by the filter within a unit time. The greater the amount of particulate in the filter, the greater the heater power consumption required to remove the particulate in the filter. Therefore, the particulate amount of the inflow gas to the filter can be calculated based on the heater power consumption.

According to the eleventh aspect, the power consumption consumed by the heater before the particulates in the filter are removed can be accurately calculated.

According to the twelfth aspect, it is possible to determine with high accuracy whether or not the particulates in the filter have been removed.

According to the thirteenth invention, the oxygen concentration sensor is provided downstream of the particulate filter. If the particulate filter can normally collect the particulates, the particulates will accumulate in the filter, and the influence of the particulate accumulation should appear in the output of this oxygen concentration sensor. Therefore, the abnormality of the particulate filter can be detected based on the output of the oxygen concentration sensor.

According to the fourteenth aspect, the oxygen concentration sensor elements are provided upstream and downstream of the particulate filter, respectively. The output difference between these oxygen concentration sensor elements corresponds to the particulate quantity in the particulate filter with high accuracy. Based on the output difference between these oxygen concentration sensor elements, the abnormality of the particulate filter can be detected with high reliability.

According to the fifteenth aspect, in the fourteenth aspect, the air-fuel ratio sensor is used as an oxygen concentration sensor. As a sensor for detecting the oxygen concentration of exhaust gas, an air-fuel ratio sensor has a proven track record. By using the air-fuel ratio sensor, it is possible to detect abnormality of the particulate filter with high reliability.

1 is a diagram illustrating a configuration of a PM sensor and an exhaust gas PM amount detection apparatus according to a first embodiment of the present invention. FIG. It is the figure which looked at the structure of FIG. 1 in the direction of arrow A. 3 is a time chart for explaining the PM amount detection operation according to the first embodiment; 3 is a flowchart of a routine that is executed by the ECU 50 in the first embodiment. It is a diagram showing an example of a map of the correlation line between values and particulates amount of [Delta] I _L and (PM amount). It is a flowchart of the routine which ECU50 performs in Embodiment 2 of this invention. It is a figure which shows the structure of the abnormality detection apparatus of the internal combustion engine concerning Embodiment 3 of this invention. 10 is a flowchart of a routine that the ECU executes in the third embodiment.

2 Internal combustion engine 10 Exhaust pipe 20 Partitions 22, 24 Air-fuel ratio sensor (A / F sensor)
30 Filter 32 Heater 34 Heater Control Unit 50 ECU (Electronic Control Unit)
130 DPF

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram illustrating a configuration of a PM sensor and an exhaust gas PM amount detection apparatus according to a first embodiment of the present invention. FIG. 2 is a view of the configuration of FIG. The PM sensor and the exhaust gas PM amount detection apparatus according to the first embodiment are suitable for an internal combustion engine for a vehicle.

The PM sensor and the PM amount detection device of Embodiment 1 are mounted on the exhaust pipe 10 of the internal combustion engine 2. There is no limitation on the number of cylinders and the method of the internal combustion engine 2. Note that the internal combustion engine 2 of FIG. 1 is illustrated in a simplified manner for convenience. An air-fuel ratio sensor 22, a filter 30, and an air-fuel ratio sensor 24 are sequentially attached to the exhaust pipe 10 in the exhaust gas flow direction. In the following description, the air-fuel ratio sensor is also referred to as “A / F sensor” for simplification. In Embodiment 1, the partition 20 shown in FIG. 1 is provided. The partition 20 has an opening on the left side and the right side in FIG. The exhaust gas flows from the left side of FIG. 1 through the partition 20 to the right side of FIG.

The filter 30 is a small particle collecting filter. The filter 30 is a miniaturized so-called diesel particulate filter (Diesel particulate filter: DPF). Hereinafter, the particulate matter (PM) is also simply referred to as “particulate” or “PM”.

A part of the exhaust gas flowing through the exhaust pipe 10 of the internal combustion engine 2 flows into the filter 30. The filter 30 can filter the particulates of the inflowing exhaust gas. As a result, particulates accumulate in the filter 30. As a result, the filter 30 can capture and collect the particulates (that is, can collect the particulates).

The filter 30 can be formed by imitating the material and specific configuration of a DPF and making its outer shape smaller than that of the DPF. The detailed structure of the filter 30 is not necessarily the same as or similar to the DPF. As shown in FIG. 2, the outer dimension of the filter 30 is smaller than the inner diameter of the exhaust pipe 10. For this reason, some of the exhaust gas flows into the filter 30, and the remaining gas does not flow into the filter 30 and flows directly downstream of the exhaust pipe 10.

The A / F sensors 22 and 24 are limit current type A / F sensors. The limit current type A / F sensor exhibits different limit current values depending on the oxygen concentration of the atmosphere, in other words, the oxygen concentration of the gas to be detected. This limit current value changes in proportion to the oxygen concentration. For this reason, the A / F sensor 22 changes the output according to the oxygen concentration of the exhaust gas upstream of the filter 30. The A / F sensor 24 also changes the output according to the oxygen concentration of the exhaust gas downstream of the filter 30.

The A / F sensors 22 and 24 include an outer electrode exposed to a detection gas, that is, an exhaust gas, an inner electrode exposed to standby, and an oxygen ion conductive electrolyte sandwiched between the outer electrode and the inner electrode. Yes. As the oxygen ion conductive electrolyte, for example, highly reliable ZrO ₂ is preferably used. Since the specific configuration of the A / F sensors 22 and 24 is not particularly limited, further description thereof is omitted.

The A / F sensors 22 and 24 are heated to a predetermined activation temperature when the engine is started by a built-in heater, and then perform air-fuel ratio sensing at the activation temperature. As shown in FIG. 1, the filter 30 and the A / F sensors 22 and 24 are separated by a predetermined distance. The distance between the filter 30 and the A / F sensors 22 and 24 is large enough that the particulates can exist in the filter 30 without burning even when the A / F sensors 22 and 24 are at the activation temperature. is there.

The filter 30 includes a heater 32 that is a small heater. The heater 32 is connected to the heater control unit 34. The inside of the filter 30 can be heated to a high temperature by the heater 32 and the particulates in the filter 30 can be removed. Thereby, the amount of particulates in the filter 30 can be made zero, and the filter 30 can be regenerated (recovery of the collection ability).

In the first embodiment, an ECU (Electronic Control Unit) 50 is connected to the A / F sensors 22 and 24 and the heater control unit 34. The ECU 50 can acquire the outputs of the A / F sensors 22 and 24, respectively. For convenience of explanation, the limit current value of the A / F sensor 22, also referred to as output current value _{I L1} or the output _{I L1,} the limit current value of the A / F sensor 24, the output current value _{I L2} or both output _{I L2} Call it. In the first embodiment, the ECU 50 stores in advance a calculation process for calculating the difference between the output I _L1 and the output I _L2 . Hereinafter, the difference between the output _{I L1} and the output _{I L2,} also referred to as [Delta] I _L.

Further, the ECU 50 can issue a control signal to the heater control unit 34 to turn on / off the heater 32 and adjust the heat generation amount.

Although not shown, in the first embodiment, the ECU 50 is also connected to a sensor (for example, an intake pressure sensor or an air flow meter) for measuring the intake air amount of the internal combustion engine 2 upstream of the exhaust pipe 10. The ECU 50 can measure the intake air amount Ga of the internal combustion engine 2 based on the output of this sensor. In the first embodiment, the ECU 50 stores a routine for calculating the exhaust gas amount Gexh based on the intake air amount Ga.

[Operation of Embodiment 1]
(PM detection principle according to the first embodiment)
As a result of intensive research, the inventor of the present application has come up with a particulate amount detection method based on a novel detection principle that has not been known. That is, when the particulates are filtered by a small filter such as the filter 30, the diffusion distance of the gas (oxygen: O ₂ ) passing through the small filter changes.

The greater the amount of particulates in the filter, the longer the diffusion distance of gas passing through the small filter. As the amount of particulates in the filter increases, the amount of O ₂ that can pass through the small filter decreases, and as a result, the oxygen concentration downstream of the small filter decreases. Therefore, it is possible to detect the particulate amount of the gas flowing into the small filter based on the oxygen concentration downstream of the small filter.

In the above series of phenomena, the small filter plays the same role as the diffusion-controlled layer in the limiting current type A / F sensor. When the limiting current type A / F sensor is arranged downstream of the small filter, the oxygen diffusion distance in the total layer of the small filter and the diffusion-controlling layer of the limiting current type A / F sensor is determined by the parameter in the filter. It increases as the amount of curate increases. As a result, the limit current value of the downstream limit current type A / F sensor decreases as the amount of particulates in the filter increases.

When limiting current type A / F sensors are arranged upstream and downstream of the small filter, the output difference between the upstream and downstream limiting current type A / F sensors increases as the amount of particulates in the filter increases. Go. Therefore, it is possible to detect the particulate amount of the inflowing gas to the small filter based on the output difference between the upstream and downstream limiting current type A / F sensors.

(Specific operation of the first embodiment)
When exhaust gas having an air-fuel ratio and a certain particulate amount in the filter 30 flows in, the A / F sensor 22 shows a specific output corresponding to the air-fuel ratio. On the other hand, the output of the A / F sensor 24 changes according to the amount of particulates in the filter 30 as described above. As the exhaust gas continues to flow into the filter 30, the amount of particulates in the filter 30 increases. When the amount of particulates in the filter 30 increases, the ambient oxygen concentration of the A / F sensor 24 decreases, and _IL2 decreases. As a result, since the output I _L1 is constant while the output I _L2 is decreased, ΔI _L is increased.

Same time, the same exhaust gas flow rate, exhaust gas is the more particulate content contained, [Delta] I _L Gayori greatly increased. Therefore, based on [Delta] I _L, the particulates of the exhaust gas which flows the current to the filter 30 can be calculated. Accordingly, it is possible to detect the particulate generation amount of the internal combustion engine 2.

The PM amount detection method according to the first embodiment will be described more specifically with reference to FIG. FIG. 3 is a time chart for explaining the PM amount detection operation according to the first embodiment. In the PM amount detection operation of the first embodiment, the three steps A, B, and C are repeatedly performed. In the first embodiment, it is assumed that the A / F sensors 22 and 24 are kept constant at the activation temperature.

In step A, first, a control signal is sent from the ECU 50 to the heater control unit 34, and the heater 32 is heated. The particulate matter in the filter 30 is removed (burned) by the heating of the heater 32, and the particulate matter in the filter 30 once becomes zero. In the first embodiment, the output zero point correction is also performed in step A in order to eliminate the output deviation (output deviation) between the A / F sensor 22 and the A / F sensor 24. The output zero point correction, [Delta] I _L indicates a value corresponding to the particulate amount in the filter 30 with high accuracy.

In step B, the heater 32 is turned off. As a result, the temperature of the filter 30 decreases and particulates begin to accumulate in the filter 30. In Step B, a standby state is maintained until a predetermined time elapses in this state.

In Step C, when a predetermined time has elapsed from Step B, the ECU 50 acquires the output I _L1 and the output I _L2 and calculates ΔI _L. Based on the predetermined time (that is, the particulate collection period) between the above steps B → C and the total amount of the exhaust gas amount Gexh that has flowed during this time, the particulate amount per unit time and per unit gas amount Is calculated.

After step C, step A is continued. Thereafter, steps A, B, and C are repeatedly performed, so that the amount of particulates can be continuously detected. According to the first embodiment, during the operation of the internal combustion engine 2, the quantitative detection of the exhaust gas particulates can be continuously performed every predetermined time (predetermined cycle).

As described above, according to the first embodiment, the output variation of the A / F sensor 24 (an output decrease) that is based on [Delta] I _L, to detect the particulate amount of the exhaust gas flowing into the filter 30 Can do. Further, according to the first embodiment, A / F sensors can be provided on the upstream side of the filter 30 and the downstream side of the filter 30, respectively. By measuring the difference [Delta] I _L of the A / F sensor 22 can detect the particulate amount of increase in the filter 30 with high accuracy. As a result, it is possible to detect the particulate amount of the gas flowing into the filter with high accuracy.

Further, according to the first embodiment, since the particulate matter of the filter 30 can be heated and removed by the heater 32, the detection of the particulate amount can be repeated. The filter 30 is small, and the power consumption of the heater 32 is small even if the particulates are repeatedly removed by heating. Therefore, the influence on the fuel consumption can be reduced.

Further, according to the first embodiment, it is possible to detect the particulate amount of the exhaust gas using the A / F sensors 22 and 24. As a sensor for detecting the oxygen concentration of exhaust gas, an air-fuel ratio sensor has a proven track record. By using the air-fuel ratio sensor, the particulate quantity of the exhaust gas can be detected with high reliability.

Also, the air-fuel ratio sensor generally operates in a state heated to a predetermined activation temperature. When the filter 30 reaches a temperature higher than a specific temperature (particulate combustion temperature), the particulates burn without being accumulated in the filter 30. In this regard, according to the first embodiment, the A / F sensors 22 and 24 and the filter 30 are separated from each other. Therefore, the filter 30 can reliably hold the particulates even while the temperature of the A / F sensors 22 and 24 is the activation temperature. As a result, the particulate matter amount of the exhaust gas can be detected while the A / F sensors 22 and 24 are at the activation temperature. Furthermore, according to the first embodiment, the temperatures of the A / F sensors 22 and 24 are kept constant at the activation temperature, and the temperature dependence of the outputs of the A / F sensors 22 and 24 is small. Therefore, there is an advantage that output temperature correction and a temperature sensor for temperature correction are not required.

[Specific Processing in First Embodiment]
Hereinafter, a specific process performed by the exhaust gas PM amount detection apparatus according to the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart of a routine executed by ECU 50 in the first embodiment. The routine of FIG. 4 is executed when the internal combustion engine 2 is started. Figure 5 is a diagram showing an example of a map of the correlation line between values and particulates amount of [Delta] I _L (PM amount). FIG. 5 shows correlation lines for air-fuel ratio = 20 and 25, respectively. In the first embodiment, the ECU 50 stores a correlation map of air-fuel ratio = 20 shown in FIG. 5 in advance.

In the routine shown in FIG. 4, first, A / F sensor heating and heater control are performed (step S100). In this step, after the internal combustion engine 2 is started, the heaters built in the sensors are heated until the A / F sensors 22 and 24 are activated. At the same time, the heater 32 is also controlled, and the filter 30 is heated to the particulate combustion temperature.

Subsequently, after determination of sensor activity and PM combustion, output zero point correction of the A / F sensor is performed (step S102). In this step S102, it is first determined whether or not the A / F sensors 22 and 24 are active. The sensor activity determination can be made based on, for example, whether or not the output error of the A / F sensors 22 and 24 is within a predetermined range. In step S102, PM combustion determination is also performed. The PM combustion determination is performed to determine whether or not the attached particulates of the filter 30 are completely burned. In the first embodiment, when the heating of the filter 30 by the heater 32 is continued for a predetermined time, it is determined that the particulates are completely burned.

In step S102, output zero point correction of the A / F sensor is also performed. The output zero point correction of the A / F sensor is performed in order to eliminate the output deviation (output deviation) between the A / F sensor 22 and the A / F sensor 24. This output zero point correction can be performed as follows, for example. First, a coefficient k to be multiplied by the output current of the A / F sensor 24 is derived so that the output of the A / F sensor 22 matches the output of the A / F sensor 24. The coefficient k is multiplied by the output current of the A / F sensor 24. Thereby, every time the process of step S102 is performed, the output difference is canceled and the output zero point correction is realized.

Subsequently, the heater 32 is turned off (step S104). When the heater 32 is turned off, the temperature of the filter 30 is lowered, and the filter 30 is sufficiently cooled to a temperature at which the particulates can be accumulated in the filter 30. Thereafter, particulates accumulate in the filter 30.

After the heater is turned off, the ECU 50 executes a filter temperature determination process for determining whether or not the temperature of the filter 30 has become low enough to accumulate particulates. In this filter temperature determination, for example, it may be determined whether the temperature of the heater 32 has become sufficiently low based on a comparison between the resistance value of the heater 32 and a predetermined value. When the heater 32 is sufficiently low in temperature, it can be determined that the temperature of the filter 30 is sufficiently low. Alternatively, if the [Delta] I _L is increased to a predetermined determination amount, it may be determined that the temperature of the filter 30 is sufficiently low. If the filter temperature determination process is satisfied, the time is measured from the time when the condition is satisfied.

At the same time after the start of time measurement in step S104, a process of calculating the integrated exhaust gas amount is started (step S106). In this step, the ECU 50 accumulates the exhaust gas amount Gexh. Hereinafter, the integrated value of Gexh is also referred to as an integrated exhaust gas amount “Gexh_itg”.

Thereafter, A / F sensor output storage and exhaust gas amount storage are performed (step S108). In this step, the outputs of the A / F sensors 22 and 24 when the predetermined time T ₀ has elapsed after the start of time measurement in step S104 are stored. Further, the exhaust gas amount Gexh is also stored at the timing when the outputs of the A / F sensors 22 and 24 are stored. In the first embodiment, the exhaust gas amount Gexh stored here is used to correct the exhaust gas pressure dependency of the A / F sensors 22 and 24.

According to the series of processing in steps S104 to S108, the A / F sensor output storage and the exhaust gas amount storage are performed after a predetermined time has elapsed since it was confirmed that the particulates started to accumulate in the filter 30. it can.

Note that the internal combustion engine 2 may be operated under predetermined operating conditions during steps S104 to S108. Under this predetermined operating condition, the output storage of the A / F sensors 22 and 24 and the exhaust gas amount storage may be performed after the predetermined time T ₀ has elapsed. If the engine operating area where you want to detect the PM amount has been determined, or if you want to detect the PM amount when there is a certain amount of particulate generation from the viewpoint of detection accuracy, the operating conditions for detecting the PM amount are It may be determined in advance.

After step S108, [Delta] I _L calculation process is executed (step S110). In this step, first, the difference between the output values stored in step S108 is calculated. Next, in the first embodiment, the difference obtained by this calculation is converted into a reference current value according to the air-fuel ratio and the exhaust gas amount Gexh. In the first embodiment, the reference current value is the output current value of the A / F sensors 22 and 24 when the air-fuel ratio = 20 and the exhaust gas amount is 10 g / s. Reference is unified by the terms of the final [Delta] I _L is calculated.

Next, a process for calculating the PM amount from the correlation line is executed (step S112). In step S112, as shown in FIG. 5, by map correlation line of the air-fuel ratio = 20 have been established is referenced, PM amount corresponding to [Delta] I _L after conversion is calculated. Specifically, in this process, as shown in the map of FIG. 5, as the PM amount is large [Delta] I _L is often calculated.

The following effects can be obtained by the processes in steps S110 and S112. For example, as shown in FIG. 5, the difference ΔI _L2 obtained when the air-fuel ratio = 25 coincides with ΔI _L1 when the air-fuel ratio = 20 by being converted into a reference current value. Relation PM amount and the [Delta] I _L will vary according to the air-fuel ratio of the exhaust gas. As shown in FIG. 5, when ΔI _L1 is obtained when the air-fuel ratio is 20, the amount of PM corresponding to this ΔI _L1 is determined. On the other hand, when ΔI _L2 is obtained when the air-fuel ratio is 25, even if ΔI _L2 is larger than ΔI _L1 , the PM amount is the same as ΔI _L1 when air-fuel ratio = 20. In the first embodiment, the output difference of the A / F sensors 22 and 24 obtained at different exhaust gas air-fuel ratios is converted into a value corresponding to the air-fuel ratio = 20 by the conversion process in step S110. After this conversion is performed, a map in which a correlation line of air-fuel ratio = 20 is defined is referred to. As a result, the PM amount can be accurately detected based on the outputs of the A / F sensors 22 and 24 even in a situation where the air-fuel ratio changes every moment.

Subsequently, the PM amount corresponding to the exhaust gas amount is calculated (step S114). In this step, the integrated exhaust gas amount Gexh_itg stored in step S108, based on the predetermined time T _0, per and per unit amount of gas per unit time, the particulate amount is calculated. Thereby, quantitative evaluation of particulates in exhaust gas can be performed.

Subsequently, the heater 32 is heated again, and the particulates in the filter 30 are removed (step S116). Thereafter, the process returns to step S102, and the processes after step S102 are repeatedly executed.

According to the above processing, the amount of exhaust gas particulates can be detected.

Incidentally, the map that defines the relationship between [Delta] I _L and PM amount to be stored in ECU50 is correlation line for each of a plurality of air-fuel ratio of 20, 25 and other is determined, it may be a so-called multi-dimensional map. Thus, the PM amount may be calculated by directly referring to the correlation line for each air-fuel ratio without converting to the reference current value in step S110. In the first embodiment, the ECU 50 calculates the exhaust gas amount Gexh based on the intake air amount Ga. For this reason, the integrated value of the intake air amount Ga can be used instead of the integrated exhaust gas amount Gexh_itg.

In the first embodiment described above, the filter 30 is the “filter” in the first invention, the heater 32 is the “heater” in the first invention, and the A / F sensor 24 is the first filter. Corresponds to the “oxygen concentration sensor element” in the invention. In the first embodiment, the A / F sensor 22 corresponds to the “oxygen concentration sensor element” in the second invention.

In the first embodiment described above, the filter 30 is the “filter” in the fifth invention, the air-fuel ratio sensor 24 is the “oxygen concentration sensor element” in the fifth invention, and the heater 32 is This corresponds to the “heater” in the fifth invention. In the first embodiment, the ECU 50 executes the process of step S100 or step S116 in the routine of FIG. 4, so that the “heating control means” in the fifth aspect of the invention causes the ECU 50 to execute the process of step S104. Thus, the “temperature reduction control means” in the fifth invention causes the ECU 50 to execute the process of step S108, and the “acquisition means” in the fifth invention enables the ECU 50 to execute the processes of steps S110 to S114. By executing this, the “calculation means” in the fifth aspect of the present invention is realized.

In the first embodiment, the predetermined time T _{0 corresponds} to the “predetermined time” in the sixth invention, and the accumulated exhaust gas amount Gexh_itg corresponds to the “integrated value” in the sixth invention. .

In the first embodiment, the “calibration means” according to the ninth aspect of the present invention is implemented by the ECU 50 executing the process of step S102 in the routine of FIG.

[Modification of Embodiment 1]
(First modification)
In the first embodiment, the A / F sensors 22 and 24 are limit current type air-fuel ratio sensors. However, the present invention is not limited to this. As described above, as the amount of particulates in the filter 30 increases, the amount of O ₂ that can pass through the small filter decreases, and as a result, the oxygen concentration downstream of the filter 30 decreases. In the first embodiment, this phenomenon is used to detect the particulate amount of the inflow gas to the filter 30 based on the oxygen concentration downstream of the filter 30. Therefore, an air-fuel ratio sensor of a system other than the limit current type, for example, a so-called 2-cell type air-fuel ratio sensor may be used instead of the A / F sensors 22 and 24. An oxygen concentration sensor that can measure the oxygen concentration of gas other than the air-fuel ratio sensor may be used instead of the A / F sensors 22 and 24.

(Second modification)
In the first embodiment, one A / F sensor is provided upstream and downstream of the filter 30. However, the present invention is not limited to this. As described above, as the amount of particulates in the filter 30 increases, the amount of O ₂ that can pass through the small filter decreases, and as a result, the oxygen concentration downstream of the filter 30 decreases. Accordingly, only the filter 30 downstream provided A / F sensor, the output reduction of the A / F sensor (hereinafter, [Delta] I _Ld) may be used in place of the in [Delta] I _L. However, when an A / F sensor or an oxygen concentration sensor is provided only downstream of the filter, the oxygen concentration of the exhaust gas upstream of the filter 30 cannot be detected by the sensor. In this case, for example, the air-fuel ratio or oxygen concentration calculated based on the operating condition of the internal combustion engine 2, the difference between the output of the filter downstream of the A / F sensor or an oxygen concentration sensor may be a [Delta] I _L .

(Third Modification)
In the first embodiment, the “PM sensor” according to the first aspect of the present invention is configured by combining the A / F sensors 22 and 24, the filter 30, and the heater 32 as individual components. However, the present invention is not limited to this. One PM sensor in which the functions of the A / F sensors 22 and 24, the filter 30, and the heater 32 are integrated (integrated) may be manufactured.

Specifically, a filter for filtering PM is provided in a PM sensor case having an exhaust gas inlet and an exhaust gas outlet. Further, an air-fuel ratio sensor element part or an oxygen concentration sensor element part is provided upstream and downstream of the filter, respectively. A heater for heating the filter is also incorporated. As described above, a PM sensor including an exhaust gas inlet and an outlet and including a filter, an oxygen concentration sensor element portion, and a heater is provided. When this PM sensor is disposed in the exhaust passage, a part of the exhaust gas is extracted through the inlet and flows into the PM sensor case. The exhaust gas flowing in from the inflow port passes through the filter and then flows out again from the outflow port into the exhaust passage. In this configuration, by treating the output difference of the oxygen concentration sensor element of the filter upstream and downstream similarly to the [Delta] I _L of the first embodiment, it is possible to detect the particulate matter of the exhaust gas.

According to the integrated PM sensor according to the present modification, the influence of the exhaust gas flow rate and the air-fuel ratio can be reduced as compared with the configuration of the first embodiment. Detection can be performed. In the case of performing the above integration, it is preferable that the heat insulation around the filter is sufficiently secured so that the filter can maintain the particulates even while the temperature of the air-fuel ratio sensor element is the active temperature. Note that, as described in the second modification, the air-fuel ratio sensor element unit or the oxygen concentration sensor element unit may be provided only downstream of the filter.

(Fourth modification)
In the first embodiment, the following calculation process can be modified. First, the ECU 50 stores a map (first map) between the values of I _L1 and I _L2 and the oxygen concentration. The ECU 50 also stores a correlation line map (second map) that defines the relationship between the oxygen concentration difference ΔO ₂ upstream and downstream of the filter 30 and the PM amount. This second map can be determined so that the PM amount increases as the oxygen concentration difference ΔO ₂ increases. After the ECU 50 acquires I _L1 and I _L2 in step S108, an oxygen concentration value corresponding to these values is calculated according to the first map. Next, based on the difference in oxygen concentration value, the PM amount is calculated according to the second map. The processing in steps S110 and S112 may be replaced by such a calculation process.

Embodiment 2. FIG.
[Configuration of Embodiment 2]
The PM amount detection device of the second embodiment has a configuration in which a circuit for measuring the power consumption of the heater 32 is added to the configuration of the first embodiment. The specific configuration of this circuit is not particularly limited, and a circuit provided with a current sensor and a voltage sensor for measuring the current and applied voltage of the heater 32 may be used. Except for this point, the hardware configurations of the first and second embodiments are the same, and therefore the hardware configuration of the second embodiment is not shown for the sake of simplicity of explanation. The PM amount detection apparatus according to the second embodiment is realized by causing the ECU 50 to execute the routine of FIG.

In the following description, the power consumption of the heater 32 is also referred to as “P _H ”. The amount obtained by integrating the power P _H at the time of the heater 32, that is, the power consumption of the heater 32, also referred to as "W _H".

[Operation of Embodiment 2]
As the amount of particulates in the exhaust gas increases, the amount of particulates collected by the filter 30 within a unit time increases. The greater the amount of particulates in the filter 30, the greater the power consumption of the heater 32 required to remove the particulates in the filter 30. Therefore, in the second embodiment, the particulate amount of the gas flowing into the filter 30 is calculated based on the power consumption amount of the heater 32.

[Specific Processing of Embodiment 2]
A specific process performed by the exhaust gas PM amount detection apparatus according to the second embodiment will be described below with reference to FIG. FIG. 6 is a flowchart of a routine executed by the ECU 50 in the second embodiment of the present invention. In the second embodiment, a map of a correlation line between _WH and the PM amount is stored in the ECU 50 in advance. This map, like the map of FIG. 5 in the first embodiment, can be defined as such amount of PM increases W _H is large.

In the routine of FIG. 6, first, step S100 described in the first embodiment is executed.

Next, storage of I _L1 , I _L2 , and Gexh and calculation of ΔI _L are performed (step S208). In the second embodiment, the ECU 50 is provided with a sequential storage process for repeatedly storing (sampling) the outputs I _L1 and I _L2 of the A / F sensors 22 and 24 at predetermined intervals (for example, every 8 milliseconds). . In the second embodiment, the ECU 50 is also provided with a sequential storage process for storing the exhaust gas amount Gexh at the same timing as the storage of the outputs I _L1 and I _L2 . In step S208, the ΔI _L calculation process in steps S108 and S110 is repeatedly performed based on the stored values I _L1 , I _L2 , and Gexh of the sequential storage process. In the second embodiment, ECU 50 performs continue these processes in step S208 and subsequent, [Delta] I _L is sequentially updated to the latest values.

Next, step S104 described in the first embodiment is executed, and the heater is turned off. Thereafter, in response to the gradually accumulated particulate filter 30, the value of [Delta] I _L being sequentially calculated, gradually increases.

Then, if [Delta] I _L reaches a predetermined value, time counting is started (step S213). By this step, time counting is started when a predetermined degree of particulates is accumulated in the filter 30. As a result, the subsequent processing can proceed under a situation where the particulates are reliably collected in the filter 30. As a result, it is possible to ensure the estimation accuracy of the PM amount calculation and to reduce the heater power consumption under the condition that the particulates are not collected.

Subsequently, when the time at which the counting is started in step S213 reaches a predetermined time (hereinafter, “T ₁ ”), the heater is turned on (step S214). After ON of the heater 32, the power supplied to the heater 32 at a predetermined amplitude _{P 0} and a predetermined duty ratio _{D H.} At this time, the heater 32 is controlled so that at least the filter 30 can be heated to the particulate combustion start temperature or higher. In the second embodiment, the time is counted after the heater 32 is turned on.

After starting the control of the heater 32 in step S214, the filter 30 is heated by the heater 32, and the particulates in the filter 30 are combusted and removed. Along with this, the value of ΔI _L gradually decreases.

Thereafter, the power consumption until ΔI _L becomes zero is calculated (step S216). In the second embodiment, first, the heater 32 is turned ON, the determination process of whether [Delta] I _L becomes zero is performed. [Delta] I L _{= 0} the time counted by the timing established is stopped, the time T _H from ON time of the heater 32 to the [Delta] I _L becomes zero is obtained. Subsequently, the multiplication of the time _{T H} and the above _{P 0} and calculation process of calculating the power consumption _{W H} on the basis of the duty ratio _{D H} (specifically, for example, _{T H × P 0 × D H} = W H ) Is executed. The calculated power consumption amount _WH is the amount of power consumed by the heater 32 in order to remove the particulates in the filter 30.

Next, the PM amount corresponding to the exhaust gas amount is calculated (step S218). In this step, first, a map of correlation lines between the _WH and the PM amount stored in the ECU 50 is referred to calculate the PM amount corresponding to the _WH . Thereafter, as in the first embodiment, the integrated exhaust gas amount Gexh_itg, on the basis of a predetermined time T _0, per and per unit amount of gas per unit time, the particulate amount is calculated.

Thereafter, the heater 32 is heated again, and the particulates in the filter 30 are removed (step S220). Thereafter, the process returns to step S208, and the processes after step S208 are repeatedly executed.

According to the above processing, the amount of exhaust gas particulates can be detected.

In the second embodiment described above, the filter 30 corresponds to the “filter” in the tenth invention, and the heater 32 corresponds to the “heater” in the tenth invention. In the second embodiment, the ECU 50 executes the process of step S212 in the routine shown in FIG. 6, so that the “temperature reduction control” in the tenth aspect of the invention causes the ECU 50 to execute the processes of steps S213 and S214. Thus, the “heating control means” in the tenth aspect of the invention causes the ECU 50 to execute the process of step S216, and the “power amount detection means” in the tenth aspect of the invention causes the ECU 50 to execute the process of step S220. As a result, the “calculation means” in the tenth aspect of the present invention is realized.

In the second embodiment, in step S216 of the routine of FIG 6, by [Delta] I _L is zero process of determining whether or not the ECU50 executes, the "determination means" in the eleventh aspect of the present invention, time T _H and by ECU50 calculation processing for calculating a power consumption amount W _H on the basis of the above P ₀ and the duty ratio D _H is executed, the first 11 "electric power calculation means" in the invention of, be implemented respectively Yes.

Although the hardware configuration is not shown in the second embodiment, the A / F sensor 22 is the “upstream oxygen concentration sensor” in the twelfth invention, and the A / F sensor 24 (not shown) is the first sensor. This corresponds to the “downstream oxygen concentration sensor” in each of the 12 inventions.

[Modification of Embodiment 2]
The specific processing of the second embodiment, at step S214, the output of the A / F sensor 22, 24 when a predetermined time _{T 1} is passed is stored. However, the present invention is not limited to this. Instead of the predetermined time _{T 1,} when the integrated exhaust gas amount Gexh_igt has reached a predetermined amount, ECU 50 may store the output of the A / F sensor 22, 24.

The control of the heater 32 is not necessarily limited to the duty control as in step S214. For example, electric power may be applied to the heater 32 so that the resistance value of the heater 32 (temperature of the heater 32) shows a predetermined value. In this case, the power consumption may be calculated by monitoring the power consumption of the heater 32.

In the second embodiment, the following modifications can be given. In this modified example, when a predetermined time has elapsed since the heater was turned off in step S212 (or when the accumulated exhaust gas amount has reached a predetermined amount), processing after the heater is turned on in step S214 is executed. That is, in this modification, the predetermined value comparison [Delta] I _L has been removed in step S213.

Further, the modification example described in the first embodiment may be combined with the second embodiment.

Embodiment 3 FIG.
[Configuration of Embodiment 3]
FIG. 7 is a diagram showing the configuration of the abnormality detection apparatus for an internal combustion engine according to the third embodiment of the present invention. The abnormality detection device of the third embodiment can detect an abnormality of the diesel particulate filter (DPF) 130 provided in the exhaust pipe 10. This abnormality detection device can be used for OBD (On-board diagnosis) when mounted on a vehicle.

In Embodiment 3, the internal combustion engine 2 is assumed to be a diesel engine, and a heating mechanism (not shown) for regenerating the DPF 130 is provided. The ECU 50 can regenerate the DPF 130 by controlling the heating mechanism.

Various configurations of the heating mechanism for DPF regeneration are already known. For this reason, although detailed description is not given, you may heat DPF130 by what is called post injection, for example. Specifically, an exhaust system fuel addition valve may be provided in the exhaust passage of the internal combustion engine 2. The exhaust system fuel addition valve is provided to add fuel to the exhaust gas flowing through the exhaust passage. The DPF 130 can be regenerated by adding fuel with an exhaust system fuel addition valve at an appropriate timing. In addition, so-called post injection may be performed to add fuel. Further, a heater may be attached to the DPF 130 and the DPF 130 may be heated by this heater.

As shown in FIG. 7, A / F sensors 22 and 24 are provided upstream and downstream of the DPF 130, as in the case of the filter 30 of the first embodiment. Also in DPF130, like the filter 30, in accordance with the increase particulates, [Delta] I _L is increased. DPF130 is if successfully collecting particulates, particulates continue to accumulate in the DPF130, the influence of the particulate accumulation should appear in ΔI _L. Therefore, based on [Delta] I _L, it is possible to detect the abnormality of DPF130.

[Specific Processing of Embodiment 3]
FIG. 8 is a flowchart of a routine executed by ECU 50 in the third embodiment. The routine in FIG. 8 is executed when the internal combustion engine 2 is started. In the following description, the description overlapping with the contents of the above-described first and second embodiments will be omitted or simplified as appropriate.

In the routine of FIG. 8, first, heating for activating the A / F sensor is performed (step S300) as in step S100 of the first embodiment.

Subsequently, DPF regeneration control is executed (step S302). In this step, the ECU 50 controls the heating mechanism described above, and the particulates in the DPF 130 are removed.

Subsequently, steps S102, S106, S108, and S110 are executed as in the first embodiment. Thus, activity determination processing of the A / F sensor, PM combustion determination process in DPF130, outputs the zero point correction process of the A / F sensor, calculation of the integrated exhaust gas amount Gexh_itg, and calculation of [Delta] I _L are sequentially performed Is done.

Next, the PM amount is calculated (step S304). In this step, as in step S112 of the first embodiment, based on [Delta] I _L, in accordance with the correlation lines, PM amount is calculated. Also in the third embodiment, a map of correlation lines as shown in FIG. 5 is created in advance, and this map is stored in the ECU 50.

Next, it is determined whether the PM amount is equal to or less than a predetermined value (step S306). As described above, if the DPF 130 can normally collect the particulates, the particulates should be accumulated in the DPF 130. Contrary to this expectation, if the amount of PM in the DPF 130 shows a predetermined value or less, it is considered that some abnormality has occurred in the DPF 130. Therefore, in the third embodiment, it is determined whether the PM amount is equal to or less than a predetermined value. If this condition is negative, it is determined that the DPF 130 is normally collecting particulates, and the current routine is terminated.

If the condition of step S306 is satisfied, it is determined that there is an abnormality in the DPF 130 (step S308). When the abnormality detection apparatus according to the third embodiment is used for OBD, for example, a warning is given to the driver by lighting a warning lamp.

According to the above processing, the abnormality of the particulate filter can be detected.

Note that in the third embodiment, after calculating the amount of PM from [Delta] I _L, was determined based on a comparison between the PM amount and a predetermined value. However, the present invention is not limited to this. Without conversion to the PM amount, by comparing the [Delta] I _L with a predetermined value, it may be performed comparison determination.

In the third embodiment described above, the DPF 130 corresponds to the “particulate filter” in the thirteenth invention, and the A / F sensor 24 corresponds to the “oxygen concentration sensor” in the thirteenth invention. Yes. Further, in the third embodiment, the ECU 50 executes the process of step S302 of the routine of FIG. 8, so that the “heating means” in the thirteenth aspect of the invention is changed to steps S110, S304, S306 of the routine of FIG. By executing the processing of S308 and S308, the “detection means” in the thirteenth aspect of the present invention is realized.

In the third embodiment described above, the A / F sensor 22 corresponds to the “oxygen concentration sensor” in the fourteenth aspect of the invention.

Claims (15)

1. An inflow port for extracting and flowing in part of the gas in the exhaust passage of the internal combustion engine;
   A filter for filtering particulate matter (PM) in the gas flowing into the inlet;
   A heater attached to the filter and capable of changing a temperature of the filter;
   An outlet for allowing the gas that has passed through the filter to flow into the exhaust passage;
   An oxygen concentration sensor element that is arranged on the outlet side and changes an output according to the oxygen concentration of the gas that has passed through the filter;
   PM sensor characterized by comprising.
2. The PM sensor according to claim 1, further comprising an oxygen concentration sensor element that is disposed between the inlet and the filter and changes an output according to an oxygen concentration of a gas flowing from the inlet.
3. The PM sensor according to claim 2, wherein the oxygen concentration sensor element on the outlet side and the oxygen concentration sensor element on the inlet side are air-fuel ratio sensor elements.
4. The air-fuel ratio sensor element includes a heater and is heated to a predetermined temperature by the heater during operation,
   When the temperature of the air-fuel ratio sensor element is the predetermined temperature, the filter and the air-fuel ratio sensor element are separated from each other so that the filter has a temperature at which particulate matter in the filter is not removed. The PM sensor according to claim 3, wherein:
5. A filter that is provided in an exhaust passage of an internal combustion engine and filters particulate matter (PM) in exhaust gas flowing through the exhaust passage;
   An oxygen concentration sensor element that is disposed downstream of the filter in the exhaust passage and changes an output according to the oxygen concentration of the gas that has passed through the filter;
   A heater attached to the filter;
   Heating control means for controlling the heater so that the filter is heated until the particulate matter in the filter is removed;
   Temperature reduction control means for controlling the heater so that the temperature of the filter is equal to or lower than the temperature at which the particulate matter in the filter is not removed after the control of the heating control means;
   Obtaining means for obtaining an output of the oxygen concentration sensor element after the temperature of the filter becomes equal to or lower than the temperature;
   Calculation means for calculating a particulate matter amount of the exhaust gas based on the output acquired by the acquisition means;
   An exhaust gas PM amount detection device comprising:
6. The acquisition means acquires the output of the oxygen concentration sensor element when a predetermined time has elapsed after the temperature of the filter becomes equal to or lower than the temperature,
   Means for calculating an integrated value of the amount of exhaust gas flowing into the filter by the acquisition timing of the output of the acquisition means after the temperature of the filter becomes equal to or lower than the temperature;
   The calculation means calculates the particulate matter amount of the exhaust gas per unit time and per unit volume based on the output acquired by the acquisition means, the predetermined time, and the integrated value. The exhaust gas PM amount detection device according to claim 5.
7. An oxygen concentration sensor element disposed upstream of the filter in the exhaust passage and capable of changing an output according to an oxygen concentration of exhaust gas flowing into the filter;
   The calculating means calculates a particulate matter amount of the exhaust gas based on a difference between an output of the oxygen concentration sensor element upstream of the filter and an output of the oxygen concentration sensor element downstream of the filter; The exhaust gas PM amount detection device according to claim 5 or 6, characterized in that:
8. The exhaust gas PM amount detection device according to claim 7, wherein the oxygen concentration sensor element on the downstream side of the filter and the oxygen concentration sensor element on the upstream side of the filter are air-fuel ratio sensor elements.
9. The exhaust gas PM according to claim 8, further comprising calibration means for calibrating an output deviation between the air-fuel ratio sensor on the downstream side of the filter and the air-fuel ratio sensor on the upstream side of the filter. Quantity detection device.
10. A filter that is provided in an exhaust passage of an internal combustion engine and filters particulate matter (PM) in exhaust gas flowing through the exhaust passage;
    A heater attached to the filter;
    Temperature reduction control means for controlling the heater so that the temperature of the filter is equal to or lower than a temperature at which particulate matter in the filter is not removed;
    The temperature of the filter becomes equal to or higher than the temperature at which the particulate matter in the filter is removed after a lapse of a predetermined period from when the temperature of the filter becomes equal to or lower than the temperature by the control of the temperature reduction control means. Heating control means for controlling the heater;
    A power amount detecting means for detecting a power consumption amount consumed by the heater to remove particulate matter in the filter when the control of the heating control means is performed;
    Calculation means for calculating a particulate matter amount of the exhaust gas based on the power consumption detected by the power detection means;
    An exhaust gas PM amount detection device comprising:
11. The power amount detection means
    Determination means for determining whether or not the particulate matter in the filter has been removed after the start of the control of the heating control means;
    A power amount calculating means for calculating a power consumption amount of the heater during a period from the start of the control of the heating control means until it is determined that the particulate matter in the filter has been removed;
    Means for calculating the power consumption consumed by the heater to remove particulate matter in the filter based on the power consumption calculated by the power consumption calculating means;
    The exhaust gas PM amount detection device according to claim 10, comprising:
12. An upstream oxygen concentration sensor that is disposed upstream of the filter in the exhaust passage and changes an output according to an oxygen concentration of a gas flowing into the filter;
    A downstream oxygen concentration sensor disposed downstream of the filter in the exhaust passage and changing an output according to an oxygen concentration of a gas flowing out from the filter,
    The determination means determines whether or not the particulate matter in the filter has been removed based on the difference between the output of the upstream oxygen concentration sensor and the output of the downstream oxygen concentration sensor. The exhaust gas PM amount detection device according to claim 11.
13. An oxygen concentration sensor disposed downstream of the particulate filter provided in the exhaust passage of the internal combustion engine and changing an output in accordance with the oxygen concentration of the gas flowing out of the particulate filter;
    Heating means for heating the particulate filter so as to regenerate the particulate filter;
    Detecting means for detecting an abnormality of the particulate filter based on an output of the downstream oxygen concentration sensor after the regeneration of the particulate filter;
    An abnormality detection device for an internal combustion engine, comprising:
14. An oxygen concentration sensor disposed upstream of the particulate filter and configured to change an output according to the oxygen concentration of the exhaust gas;
    The detection unit detects an abnormality of the particulate filter based on a difference in output of the downstream oxygen concentration sensor with respect to an output of the upstream oxygen concentration sensor. Abnormality detection device for an internal combustion engine.
15. 15. The abnormality detection device for an internal combustion engine according to claim 14, wherein the oxygen concentration sensors respectively disposed upstream and downstream of the particulate filter are air-fuel ratio sensors.

Images