JP7056588B2 - Internal combustion engine control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

In Patent Document 1, as an anti-theft device for an exhaust aftertreatment device provided in an exhaust pipe of an internal combustion engine, by detecting that the electrical wiring of a temperature sensor attached to the exhaust aftertreatment device is cut, it is detected. Those that detect that the exhaust aftertreatment device has been removed from the exhaust pipe are disclosed.

Japanese Unexamined Patent Publication No. 2007-138837

However, in the case of Patent Document 1 described above, when the exhaust aftertreatment device is removed from the exhaust pipe without cutting the electrical wiring of the temperature sensor, the exhaust aftertreatment device is removed from the exhaust pipe. Cannot be detected. Therefore, for example, it is conceivable to detect the removal of the exhaust aftertreatment device based on the detection values of the temperature sensors attached before and after the exhaust aftertreatment device during the engine operation. However, if the temperature sensor fails, it becomes impossible to detect the removal of the exhaust aftertreatment device.

The present invention has been made focusing on such a problem, and an object of the present invention is to be able to detect the removal of the exhaust aftertreatment device even if the temperature sensor fails.

In order to solve the above problems, the internal combustion engine according to an embodiment of the present invention is the temperature of the engine main body, the exhaust aftertreatment device provided in the exhaust passage of the engine main body, and the exhaust gas flowing into the exhaust aftertreatment device. 1 The first exhaust temperature sensor for detecting the exhaust temperature, the second exhaust temperature sensor for detecting the second exhaust temperature which is the temperature of the exhaust discharged from the exhaust aftertreatment device, and the front-rear differential pressure of the exhaust aftertreatment device are detected. It is equipped with a differential pressure sensor. The control device of the internal combustion engine for controlling the internal combustion engine includes a time change rate calculation unit for calculating the time change rate of the first exhaust temperature and the time change rate of the second exhaust temperature, and the time change rate of the first exhaust temperature. Based on the difference between the second exhaust temperature and the time change rate of the second exhaust temperature, the first determination unit for determining whether or not the exhaust aftertreatment device is in the removed state removed from the exhaust passage, and the front-rear differential pressure. It is provided with a second determination unit for determining whether or not it is in the removed state. Then, when the first exhaust temperature sensor or the second exhaust temperature sensor is out of order, the control device of the internal combustion engine prohibits the first determination unit from determining whether or not the first exhaust gas temperature sensor is in the removed state, and the differential pressure sensor fails. When it is, it is configured to prohibit the second determination unit from determining whether or not it is in the removed state.

According to this aspect of the present invention, it is possible to detect the removal of the exhaust aftertreatment device even if the temperature sensor fails.

FIG. 1 is a schematic configuration diagram of an internal combustion engine according to the first embodiment of the present invention and an electronic control unit for controlling the internal combustion engine. FIG. 2 is a diagram showing temperature changes of the first exhaust gas temperature and the second exhaust gas temperature when the internal combustion engine is operated in the removed state in which the PM collecting device is removed. FIG. 3 is a diagram showing temperature changes of the first exhaust gas temperature and the second exhaust gas temperature when the internal combustion engine is operated in a normal state in which the PM collecting device is not removed. FIG. 4 is a flowchart illustrating the removal diagnosis of the PM collecting device according to the first embodiment of the present invention. FIG. 5 is a map for determining whether the current operating area is in the first area or the second area. FIG. 6 is a flowchart illustrating the details of the first removal diagnosis according to the first embodiment of the present invention. FIG. 7 is a flowchart illustrating the details of the first precondition determination process according to the first embodiment of the present invention. FIG. 8 is a flowchart illustrating the details of the first implementation condition determination process according to the first embodiment of the present invention. FIG. 9 is a flowchart illustrating the details of the first removal determination process according to the first embodiment of the present invention. FIG. 10 is a flowchart illustrating the details of the second removal diagnosis according to the first embodiment of the present invention. FIG. 11 is a flowchart illustrating the details of the second precondition determination process according to the first embodiment of the present invention. FIG. 12 is a flowchart illustrating the details of the second embodiment condition determination process according to the first embodiment of the present invention. FIG. 13 is a flowchart illustrating the details of the second removal determination process according to the first embodiment of the present invention. FIG. 14 is a flowchart illustrating the removal diagnosis of the PM collecting device according to the second embodiment of the present invention. FIG. 15 is a flowchart illustrating the details of the first removal determination process according to the third embodiment of the present invention. FIG. 16 is a flowchart illustrating the details of the second removal determination process according to the third embodiment of the present invention. FIG. 17 is a schematic configuration diagram of an internal combustion engine according to a fourth embodiment of the present invention and an electronic control unit for controlling the internal combustion engine. FIG. 18 is a flowchart illustrating an estimation control for calculating an estimated first exhaust temperature according to the fourth embodiment of the present invention. FIG. 19 is a map for calculating the amount of decrease in the temperature of the exhaust gas that decreases in the process of flowing through the exhaust pipe between the first exhaust gas temperature sensor and the PM collecting device, based on the intake air flow rate and the outside air temperature. Is. FIG. 20 is a flowchart illustrating the details of the first implementation condition determination process according to the fifth embodiment of the present invention. FIG. 21 is a schematic configuration diagram of a hybrid vehicle. FIG. 22A is a time chart showing temperature changes of the first exhaust temperature and the second exhaust temperature when the internal combustion engine is operated in a normal state in which the PM collecting device is not removed in a normal vehicle. FIG. 22B shows temperature changes of the first exhaust temperature and the second exhaust temperature when the internal combustion engine is operated in a normal state in which the PM collecting device is not removed in the hybrid vehicle as the engine intermittent operation implementation vehicle. It is a time chart. FIG. 23 is a flowchart illustrating the details of the first implementation condition determination process according to the sixth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, similar components are given the same reference numbers.

(First Embodiment)
FIG. 1 is a schematic configuration diagram of an internal combustion engine 100 according to the first embodiment of the present invention and an electronic control unit 200 for controlling the internal combustion engine 100.

The internal combustion engine 100 according to the present embodiment is a spark-ignition type gasoline engine, and includes an engine main body 10 having a plurality of cylinders 11 and an exhaust device 20. The type of the internal combustion engine 100 is not particularly limited, and may be a premixed compression ignition type gasoline engine or a diesel engine.

The engine body 10 generates power for driving, for example, a vehicle by burning the fuel injected from the fuel injection valve 12 inside each cylinder 11. In addition, in FIG. 1, the description of the intake device, the spark plug, etc. is omitted in order to prevent the drawing from being complicated. Further, the fuel injection method is not limited to the in-cylinder direct injection method, and may be a port injection method.

The exhaust device 20 is a device for purifying the exhaust (combustion gas) generated inside each cylinder 11 and discharging it to the outside air, and includes an exhaust manifold 21, an exhaust pipe 22, an exhaust aftertreatment device 30 and the like. To prepare for.

The exhaust generated in each cylinder 11 of the engine body 10 is collected by the exhaust manifold 21 and discharged to the exhaust pipe 22. Exhaust gas contains harmful substances such as unburned gas (carbon monoxide (CO) and hydrocarbon (HC)), nitrogen oxides (NOx), and particulate matter (PM; Particular Matter). Therefore, in the present embodiment, the exhaust pipe 22 is provided with a catalyst device 40 and a PM collecting device 50 as an exhaust aftertreatment device 30 for removing harmful substances in the exhaust. In the present embodiment, the first exhaust temperature sensor 53, the second exhaust temperature sensor 54, and the differential pressure sensor 55 are provided in the exhaust pipes 22 before and after the PM collecting device 50.

The catalyst device 40 includes a casing 41 and an exhaust gas purification catalyst 42 supported on a honeycomb-shaped carrier made of cordillite (ceramic) held in the casing 41. The exhaust gas purification catalyst 42 is, for example, an oxidation catalyst (two-way catalyst) or a three-way catalyst, and is not limited to these, and an appropriate catalyst can be used depending on the type and application of the internal combustion engine 100. In this embodiment, a three-way catalyst is used as the exhaust gas purification catalyst 42. When a three-way catalyst is used as the exhaust gas purification catalyst 42, the unburned gas (CO and HC) and NOx in the exhaust gas flowing into the catalyst device 40 are purified by the exhaust gas purification catalyst 42.

The PM collecting device 50 is provided in the exhaust pipe 22 on the downstream side in the exhaust flow direction of the catalyst device 40. The PM collecting device 50 includes a casing 51 and a wall flow type filter 52 held in the casing 51. The filter 52 collects the PM in the exhaust gas that has flowed into the PM collecting device 50. In the present embodiment, the filter 52 also carries a three-way catalyst as an exhaust gas purification catalyst, whereby the unburned gas in the exhaust gas that has flowed into the PM collection device 50 also in the PM collection device 50. And NOx can be purified. The exhaust gas purification catalyst supported on the filter 52 is not limited to the three-way catalyst, and an appropriate catalyst can be used depending on the type and application of the internal combustion engine 100.

The PM collecting device 50 is called a GPF (Gasoline Particulate Filter) when the internal combustion engine 100 is a gasoline engine, and is called a DPF (Diesel Particulate Filter) when the internal combustion engine 100 is a diesel engine. There is.

The first exhaust temperature sensor 53 is a sensor for detecting the temperature of the exhaust gas flowing into the PM collecting device 50 (hereinafter referred to as “first exhaust temperature”). In the present embodiment, the first exhaust temperature sensor 53 is attached to the exhaust pipe 22 near the inlet side of the PM collecting device 50.

The second exhaust temperature sensor 54 is a sensor for detecting the temperature of the exhaust gas flowing out from the PM collecting device 50 (hereinafter referred to as “second exhaust temperature”). In the present embodiment, the second exhaust temperature sensor 54 is attached to the exhaust pipe 22 near the outlet side of the PM collecting device 50.

The differential pressure sensor 55 is a sensor for detecting the differential pressure (hereinafter referred to as “front-rear differential pressure”) Pio between the exhaust pressure near the inlet side and the exhaust pressure near the outlet side of the PM collecting device 50.

The electronic control unit 200 is a microcomputer provided with a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), an input port, and an output port connected to each other by a bidirectional bus. ..

In addition to the first exhaust temperature sensor 53, the second exhaust temperature sensor 54, and the differential pressure sensor 55 described above, the electronic control unit 200 detects the intake air flow rate Ga [g / s] sucked into the engine body 10. An output voltage proportional to the amount of depression of the accelerator pedal (not shown) corresponding to the load (engine load) of the air flow meter 211, the outside air temperature sensor 212 for detecting the outside air temperature, and the engine body 10 is generated. Output from various sensors such as the crank angle sensor 214 that generates an output pulse every time the crank shaft (not shown) of the engine body 10 rotates by, for example, 15 ° as a signal for calculating the load sensor 213 and the engine rotation speed. The signal is input.

Then, the electronic control unit 200 controls the fuel injection valve 12 and the like based on the input output signals of various sensors and the like to control the internal combustion engine 100.

Further, the electronic control unit 200 prevents the internal combustion engine 100 from being operated in a state where the amount of harmful substances discharged to the outside air via the exhaust device 20 exceeds the regulation value set by the national government or the like. A self-diagnosis is carried out to detect an abnormality in the exhaust device 20.

For example, in the removed state where the PM collecting device 50 is removed (at the position where the PM collecting device 50 was attached, a pipe having the same diameter as the exhaust pipe 22 is connected instead of the PM collecting device 50 due to theft or vehicle modification. If the internal combustion engine 100 is operated in such a state as described above, the amount of PM discharged to the outside air via the exhaust device 20 may exceed the regulated value. Therefore, in the present embodiment, self-diagnosis of whether or not the internal combustion engine 100 is operated in the removed state in which the PM collecting device 50 is removed, that is, removal diagnosis of whether or not the PM collecting device 50 is removed is performed. are doing.

Specifically, in the present embodiment, as the removal diagnosis of the PM collecting device 50, a removal diagnosis using the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 (hereinafter referred to as “first removal diagnosis”) and It is possible to perform two types of removal diagnosis using the differential pressure sensor 55 (hereinafter referred to as "second removal diagnosis"), and which removal diagnosis should be performed according to the engine operating condition. I made it possible to use it properly.

Hereinafter, while explaining the details of the first removal diagnosis and the second removal diagnosis, the reason why these are used properly according to the engine operating state will be described.

First, the details of the first removal diagnosis using the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 will be described with reference to FIGS. 2 and 3.

FIG. 2 is a time chart showing temperature changes of the first exhaust gas temperature and the second exhaust gas temperature when the internal combustion engine 100 is operated in the removed state in which the PM collecting device 50 is removed. On the other hand, FIG. 3 is a time chart showing temperature changes of the first exhaust gas temperature and the second exhaust gas temperature when the internal combustion engine 100 is operated in a normal state in which the PM collecting device 50 is not removed.

As shown in FIG. 2A, in the removed state in which the PM collecting device 50 is removed, the heat of the exhaust flowing between the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 is the PM collecting device. Since the outside air is only radiated through the pipe connected to the position where 50 was attached, the second exhaust temperature is lower than the first exhaust temperature, but the shape of the temperature change curve of the second exhaust temperature is The shape is almost the same as the shape of the temperature change curve of the first exhaust temperature.

Therefore, as shown in FIG. 2B, the time change rate Ain [° C./s] of the first exhaust temperature (that is, the slope of the temperature change curve of the first exhaust temperature) and the time change rate Aout of the second exhaust temperature. [° C./s] (that is, the slope of the temperature change curve of the second exhaust temperature) has almost the same value, and as shown in FIG. 2C, the absolute value of the time change rate Ain of the first exhaust temperature and the second 2 The difference value Dio from the absolute value of the time change rate Aout of the exhaust temperature is basically zero.

As a result, in the removed state in which the PM collecting device 50 is removed, as shown in FIG. 2D, the integrated value IDio of the difference value Dio is also basically zero (or a value near zero).

On the other hand, as shown in FIG. 3A, in the normal state in which the PM collecting device 50 is not removed, the temperature change of the second exhaust temperature is the first by the amount of the heat capacity of the PM collecting device 50. It becomes slower than the temperature change of the exhaust temperature.

For example, as shown in FIG. 3A, when the temperature of the PM collecting device 50 is lower than the first exhaust temperature when the first exhaust temperature is rising, the exhaust gas flowing into the PM collecting device 50 Since the heat is taken by the PM collecting device 50, the increase in the second exhaust temperature is smaller than the increase in the first exhaust temperature. Therefore, when the absolute value of the time change rate Ain of the first exhaust temperature and the absolute value of the time change rate Aout of the second exhaust temperature are compared, the absolute value of the time change rate Aout of the second exhaust temperature is the first exhaust temperature. The time change rate of Ain is smaller than the absolute value of Ain.

Further, when the temperature of the PM collecting device 50 is higher than the first exhaust temperature when the first exhaust temperature is lowered, the exhaust flowing into the PM collecting device 50 receives heat from the PM collecting device 50. Therefore, the decrease in the second exhaust temperature is smaller than the decrease in the first exhaust temperature. Therefore, when the absolute value of the time change rate Ain of the first exhaust temperature and the absolute value of the time change rate Aout of the second exhaust temperature are compared, the absolute value of the time change rate Aout of the second exhaust temperature is the first exhaust temperature. The time change rate of Ain is smaller than the absolute value of Ain.

Therefore, as shown in FIG. 3 (B), the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature do not have the same value, and as shown in FIG. 3 (C). , The difference value Dio is generated. As a result, in the normal state in which the PM collecting device 50 is not removed, the integrated value IDio of the difference value Dio gradually increases as shown in FIG. 3 (D).

Therefore, during the operation of the internal combustion engine 100, the integrated value IDio of the difference value Dio between the absolute value of the time change rate Ain of the first exhaust temperature for a certain period and the absolute value of the time change rate Aout of the second exhaust temperature is If it is less than the predetermined threshold Is, it can be determined that the PM collecting device 50 is in the removed state.

As described above, in the present embodiment, it is determined whether or not the product is in the removed state based on the difference between the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature. It is also conceivable to determine whether or not the removed state is obtained simply based on the temperature difference between the first exhaust temperature and the second exhaust temperature. However, as a result of diligent research by the inventors, it has been found that the latter method causes the following problems.

That is, the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 may not be mounted in the vicinity of the PM collecting device 50, for example, due to problems in mounting space and heat resistance. Then, for example, when the first exhaust temperature sensor 53 is attached at a position away from the inlet of the PM collecting device 50, the exhaust temperature is between the first exhaust temperature sensor 53 and the PM collecting device 50. It is reduced by heat radiation from the exhaust pipe 22 in the process of flowing through the exhaust pipe 22 of the above. When the second exhaust temperature sensor 54 is attached at a position away from the PM collecting device 50, the exhaust temperature is the exhaust pipe 22 between the PM collecting device 50 and the second exhaust temperature sensor 54. It is reduced by heat radiation from the exhaust pipe 22 in the process of flowing through.

Therefore, the farther the mounting position of each exhaust temperature sensor 53, 54 is from the PM collection device 50, the more the temperature difference between the first exhaust temperature and the second exhaust temperature detected by each exhaust temperature sensor 53, 54 and the PM collection. The error between the actual temperature difference generated before and after the device 50 and the actual temperature difference becomes large. As a result, as the mounting positions of the exhaust temperature sensors 53 and 54 move away from the PM collecting device 50, it is erroneously determined that the exhaust temperature sensors 53 and 54 are in the removed state even though they are in the normal state, or they are normal even though they are in the removed state. There is a high possibility that the condition will be erroneously determined.

In this way, if it is attempted to determine whether or not the removed state is obtained simply based on the temperature difference between the first exhaust temperature and the second exhaust temperature, the mounting positions of the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 However, as the distance from the PM collecting device 50 increases, there arises a problem that the determination accuracy deteriorates due to the influence of heat radiation from the exhaust pipe 22.

On the other hand, considering the time change rate Ain of the first exhaust temperature, that is, the inclination of the temperature change curve of the first exhaust temperature, the amount of heat radiated from the exhaust pipe 22 per unit length is basically constant. 1 Even if the exhaust temperature sensor 53 is attached at a position away from the inlet of the PM collecting device 50, exhaust flows through the exhaust pipe 22 between the first exhaust temperature sensor 53 and the inlet of the PM collecting device 50. The slope of the temperature change curve of the first exhaust temperature in the process is basically constant. Therefore, the difference between the slope of the temperature change curve of the first exhaust temperature at a position away from the inlet of the PM collecting device 50 and the slope of the temperature change curve of the first exhaust temperature near the inlet of the PM collecting device 50 is. few.

Further, considering the time change rate Aout of the second exhaust temperature, that is, the inclination of the temperature change curve of the second exhaust temperature, the exhaust pipe 22 between the outlet of the PM collecting device 50 and the second exhaust temperature sensor 54 is exhausted. In the flow process, it takes a certain distance (time) for the inclination of the temperature change curve of the second exhaust temperature to change to the inclination affected by the heat radiation from the exhaust pipe 22. Therefore, the temperature of the second exhaust temperature at the position between the slope of the temperature change curve of the second exhaust temperature near the outlet of the PM collecting device 50 and a certain distance from the outlet of the PM collecting device 50. There is little difference between the slope of the change curve and the slope.

Therefore, as in the present embodiment, it is simply determined whether or not the product is in the removed state based on the difference between the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature. It is possible to more accurately determine whether or not the product is in the removed state than in the case of determining whether or not the product is in the removed state based on the temperature difference between the first exhaust gas temperature and the second exhaust gas temperature.

Subsequently, the details of the second removal diagnosis using the differential pressure sensor 55 will be described.

In the normal state in which the PM collecting device 50 is not removed, the front-rear differential pressure Pio is generated due to the pressure loss of the PM collecting device 50. On the other hand, in the removed state where the PM collecting device 50 is removed, the pressure loss is almost generated unlike the normal state because the piping or the like is only connected to the position where the PM collecting device 50 was originally attached. Therefore, the front-rear differential pressure Pio is basically a value near zero.

Therefore, for example, if the integrated value IPio (or average value APio) of the differential pressure Pio before and after a certain period is less than the predetermined threshold value IPth, it can be determined that the PM collecting device 50 is in the removed state. ..

Here, the pressure loss of the PM collecting device 50, and thus the front-rear differential pressure Pio, increases as the flow rate Ge [g / s] of the exhaust gas flowing into the PM collecting device 50 (hereinafter referred to as “exhaust flow rate”) increases. .. Therefore, the accuracy of determining whether or not the exhaust gas is in the removed state by the second removal diagnosis tends to be higher when the exhaust flow rate Ge is large than when the exhaust flow rate Ge is small. Therefore, it is desirable that the second removal diagnosis be performed in the engine operating region in which the exhaust flow rate Ge is relatively large in the engine operating region.

On the other hand, in the first removal diagnosis, as described above, in the normal state in which the PM collecting device 50 is not removed, the temperature change of the second exhaust temperature is the first by the amount of the heat capacity of the PM collecting device 50. It is determined whether or not the exhaust gas is in the removed state by utilizing the fact that the exhaust temperature becomes slower than the temperature change. Therefore, as the exhaust flow rate Ge increases, even if heat is taken by the PM collecting device 50 or heat is received from the PM collecting device 50, the temperature of the exhaust gas passing through the PM collecting device 50 changes. Therefore, the accuracy of determining whether or not the product is in the removed state by the first removal diagnosis tends to be low. That is, contrary to the second removal diagnosis, the accuracy of determining whether or not the exhaust state is in the removal state by the first removal diagnosis tends to be higher when the exhaust flow rate Ge is small than when it is large. Therefore, it is desirable that the first removal diagnosis is performed in the engine operating region where the exhaust flow rate Ge is relatively small in the engine operating region.

Therefore, in the present embodiment, the first removal diagnosis is performed in the engine operating region where the exhaust gas flow rate Ge is relatively small, and the second removal diagnosis is performed in the engine operating region where the exhaust gas flow rate Ge is relatively large. I decided to carry out. As a result, it is possible to accurately determine whether or not the engine is in the removed state in a wide engine operating area.

Further, even if the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 fails and the first removal diagnosis cannot be performed, the second removal diagnosis using the differential pressure sensor 55 can be performed. On the contrary, even if the differential pressure sensor 55 fails and the second removal diagnosis cannot be performed, the first removal diagnosis using the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 can be performed. Therefore, even if any of the first exhaust temperature sensor 53, the second exhaust temperature sensor 54, or the differential pressure sensor 55 fails, either the first removal diagnosis or the second removal diagnosis can be performed, so that the removal can be performed. It is possible to suppress the inability to determine whether or not the condition is present.

FIG. 4 is a flowchart illustrating the removal diagnosis of the PM collecting device 50 according to the present embodiment.

In step S1, the electronic control unit 200 reads the engine load calculated based on the detection value of the load sensor 213 and the engine rotation speed calculated based on the detection value of the crank angle sensor 214, and reads the engine operation state. Is detected.

In step S2, the electronic control unit 200 refers to the map of FIG. 5 and determines whether or not the current operating area is within the first area for performing the first removal diagnosis based on the engine operating state. If the current operating area is within the first area, the electronic control unit 200 proceeds to the process of step S4. On the other hand, if the current operating area is not in the first area, the electronic control unit 200 proceeds to the process of step S3.

In step S3, the electronic control unit 200 refers to the map of FIG. 5 and determines whether or not the current operating area is within the second area for performing the second removal diagnosis based on the engine operating state. If the current operating area is in the second area, the electronic control unit 200 proceeds to the process of step S5. On the other hand, if the current operating area is not in the second area, the electronic control unit 200 ends the current process.

In the present embodiment, the exhaust flow rate Ge is equal to or higher than the predetermined first flow rate Ge_th1 (for example, 2 [g / s]) and the predetermined second flow rate Ge_th2 (for example, 20 [g / s]) in the first region. The operating area is as follows. The first flow rate Ge_th1, which is the threshold value on the lower limit side of the exhaust gas flow rate Ge, is set at least in order to detect the temperature changes of the first exhaust gas temperature and the second exhaust gas temperature. This is because the exhaust needs to flow into the air. The second region is an operating region in which the exhaust flow rate Ge is a predetermined third flow rate Ge_th3 (for example, 40 [g / s]) or more, which is larger than the second flow rate Ge_th2.

Further, the exhaust flow rate Ge may be simply the intake air flow rate Ga [g / s] calculated based on the detected value of the air flow meter 211, but in the present embodiment, the intake air flow rate Ga and the fuel injection valve 12 The sum of the mass flow rate Gf [g / s] of the fuel injected from is calculated as the exhaust flow rate Ge (= Ga + Gf).

In step S4, the electronic control unit 200 performs the first removal diagnosis. Details of the first removal diagnosis will be described later with reference to FIGS. 6 to 9.

In step S5, the electronic control unit 200 performs the second removal diagnosis. The details of the second removal diagnosis will be described later with reference to FIGS. 10 to 13.

FIG. 6 is a flowchart illustrating the details of the first removal diagnosis.

In step S41, the electronic control unit 200 performs a first precondition determination process for determining whether or not the first precondition for detecting the removal of the PM collecting device 50 by the first removal diagnosis is satisfied. implement. The details of the first precondition determination process will be described later with reference to FIG. 7.

In step S42, the electronic control unit 200 determines whether or not the first precondition establishment flag Fp1 is set to 1. The first precondition establishment flag Fp1 is a flag set to 1 or 0 in the first precondition determination process. The initial value of the first precondition establishment flag Fp1 is set to 0, and it is determined that the first precondition for detecting the removal of the PM collecting device 50 is satisfied in the first precondition determination process. Sometimes set to 1. If the first precondition establishment flag Fp1 is set to 1, the electronic control unit 200 proceeds to the process of step S43. On the other hand, if the first precondition establishment flag Fp1 is set to 0, the electronic control unit 200 ends the current process.

In step S43, the electronic control unit 200 determines the first implementation condition for determining whether or not the first implementation condition for accurately detecting the removal of the PM collecting device 50 by the first removal diagnosis is satisfied. Carry out the process. The details of the first implementation condition determination process will be described later with reference to FIG.

In step S44, the electronic control unit 200 determines whether or not the first implementation condition establishment flag Fe1 is set to 1. The first implementation condition establishment flag Fe1 is a flag set to 1 or 0 in the first implementation condition determination process. The initial value of the first implementation condition establishment flag Fe1 is set to 0, and it is determined that the first implementation condition for accurately detecting the removal of the PM collecting device 50 in the first implementation condition determination process is satisfied. It is set to 1 when it is done. If the first implementation condition establishment flag Fe1 is set to 1, the electronic control unit 200 proceeds to the process of step S45. On the other hand, if the first implementation condition establishment flag Fe1 is set to 0, the electronic control unit 200 ends the current process.

In step S45, the electronic control unit 200 performs a first removal determination process for determining whether or not the PM collection device 50 has been removed. The details of the first removal determination process will be described later with reference to FIG. 7.

FIG. 7 is a flowchart illustrating the details of the first precondition determination process.

In step S411, the electronic control unit 200 determines whether or not the PM collection device 50 has been removed during this trip (during one trip of the vehicle). In the present embodiment, if the electronic control unit 200 has the implemented flag Ff1 (see FIG. 9) of the first removal determination process and the implemented flag Ff2 (see FIG. 13) of the second removal determination process described later being 0, this time. It is determined that whether or not the PM collecting device 50 has been removed during the trip is not yet performed, and the process proceeds to step S412. On the other hand, if the electronic control unit 200 has the flag Ff1 for which the first removal determination process has been performed or the flag Ff2 for which the second removal determination process has been performed is 1, is the PM collection device 50 removed during this trip? It is determined that the determination of whether or not it has already been performed once, and the process proceeds to step S415.

In step S412, the electronic control unit 200 determines whether or not the sensors necessary for calculating the parameters used for performing the first removal determination process are not broken. In the present embodiment, the electronic control unit 200 determines whether the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 are out of order. For example, the electronic control unit 200 receives when the detection values of the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 are equal to or higher than a predetermined upper limit side failure determination threshold value or equal to or lower than the lower limit side failure determination threshold value. It can be determined that a short circuit failure or a disconnection failure has occurred. Further, in the electronic control unit 200, when the detection values of the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 are the same, the difference between the detection values of the exhaust temperature sensors 53 and 54 is within a predetermined range. If the difference between the detected values of the exhaust temperature sensors 53 and 54 is not within the predetermined range, the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 are subjected to the rationality determination to determine whether or not the pressure is within the predetermined range. It can be determined that some kind of failure has occurred in.

If the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 have not failed, the electronic control unit 200 proceeds to the process of step S413. On the other hand, if either the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 fails, the electronic control unit 200 performs the process of step S415 in order to prohibit the execution of the first removal determination process described later. Proceed to.

In step S413, the electronic control unit 200 determines whether or not the sensors used for determining whether or not the first implementation condition is satisfied in the first implementation condition determination process are not broken. In the present embodiment, the electronic control unit 200 determines whether the first exhaust temperature sensor 53, the air flow meter 211, and the outside air temperature sensor 212 are out of order. If the first exhaust temperature sensor 53, the air flow meter 211, and the outside air temperature sensor 212 are not out of order, the electronic control unit 200 proceeds to the process of step S414. On the other hand, if any one of the first exhaust temperature sensor 53, the air flow meter 211, or the outside air temperature sensor 212 is out of order, the electronic control unit 200 proceeds to the process of step S415.

In step S414, the electronic control unit 200 sets the first precondition establishment flag Fp1 to 1.

In step S415, the electronic control unit 200 sets the first precondition establishment flag Fp1 to 0.

FIG. 8 is a flowchart illustrating the details of the first implementation condition determination process.

In step S431, the electronic control unit 200 determines whether or not the outside air temperature calculated based on the detection value of the outside air temperature sensor 212 is equal to or higher than a predetermined temperature (for example, −15 [° C.]). If the outside air temperature is equal to or higher than the predetermined temperature, the electronic control unit 200 proceeds to the process of step S432. On the other hand, if the outside air temperature is lower than the predetermined temperature, the electronic control unit 200 proceeds to the process of step S434. The reason for making such a determination is as follows.

As described above, in the removed state in which the PM collecting device 50 is removed, the PM collecting device 50 is attached to the heat of the exhaust flowing between the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54. The outside air will be dissipated through the piping connected to the position. At this time, when the outside air temperature is low, the amount of heat dissipated to the outside air is larger than when the outside air temperature is high. Therefore, when the outside air temperature is low, the shape of the temperature change curve of the second exhaust temperature in the removed state is the same as the shape of the temperature change curve of the first exhaust temperature due to the influence of the large amount of heat radiated to the outside air. This is because there is a possibility that the shape may not be obtained, and the accuracy of determining whether or not the product is in the removed state may decrease.

In step S432, the electronic control unit 200 determines whether or not the integrated value IGa of the intake air flow rate Ga after starting the internal combustion engine 100 is a predetermined first integrated value IGa_th1 or more. The start of the internal combustion engine 100 includes, for example, in a vehicle having an idle stop function or a hybrid vehicle, restarting when the start and stop of the internal combustion engine 100 is repeated a plurality of times during one trip. If the integrated value IGa after starting the internal combustion engine 100 is equal to or greater than the first integrated value IGa_th1, the electronic control unit 200 proceeds to the process of step S433. On the other hand, if the integrated value IGa after starting the internal combustion engine 100 is less than the first integrated value IGa_th1, the electronic control unit 200 proceeds to the process of step S434.

The reason for making such a determination is as follows. That is, immediately after the internal combustion engine 100 is started, the temperature of the pipe connected to the position where the PM collecting device 50 is attached is relatively low in the removed state in which the PM collecting device 50 is removed, and the temperature of the pipe is relatively low. The amount of heat dissipated tends to increase. Therefore, as in the case where the outside air temperature is low, the shape of the temperature change curve of the second exhaust temperature in the removed state may not be the same as the shape of the temperature change curve of the first exhaust temperature, and the removed state. This is because there is a possibility that the determination accuracy of whether or not the above is the case is lowered. The first integrated value IGa_th1 is a preset constant value in the present embodiment, but may be a variable value that increases as the stop time of the internal combustion engine 100 becomes longer, for example.

In step S433, the electronic control unit 200 sets the first implementation condition establishment flag Fe1 to 1.

In step S434, the electronic control unit 200 sets the first implementation condition establishment flag Fe1 to 0.

FIG. 9 is a flowchart illustrating the details of the first removal determination process.

In step S451, the electronic control unit 200 calculates the time change rate Ain of the first exhaust temperature based on the detection value of the first exhaust temperature sensor 53, and the second is based on the detection value of the second exhaust temperature sensor 54. The time change rate Aout of the exhaust temperature is calculated.

In step S452, the electronic control unit 200 has a difference value Dio (= | Ain | − | Aout |) between the absolute value of the time change rate Ain of the first exhaust temperature and the absolute value of the time change rate Aout of the second exhaust temperature. Is calculated.

In step S453, the electronic control unit 200 calculates the integrated value IDio (= IDio (previous value) + Dio) of the difference value Dio.

In step S454, the electronic control unit 200 calculates the number of samples Ni (= Ni (previous value) + 1) of the difference value Dio used in calculating the integrated value IDio, that is, the number of integrated difference value Dio.

In step S455, the electronic control unit 200 determines whether or not the number of samples Ni is equal to or greater than the predetermined number Nith. If the number of samples Ni is equal to or greater than the predetermined number Nith, the electronic control unit 200 proceeds to the process of step S456. On the other hand, if the number of samples Ni is less than the predetermined number Nith, the electronic control unit 200 ends the current process.

In step S456, the electronic control unit 200 determines whether or not the integrated value IDio is equal to or higher than the predetermined threshold value Is. If the integrated value IDio is equal to or higher than the predetermined threshold value Is, the electronic control unit 200 proceeds to the process of step S457. On the other hand, if the integrated value IDio is less than the predetermined threshold value Is, the electronic control unit 200 proceeds to the process of step S458.

In step S457, the electronic control unit 200 determines that the PM collecting device 50 is in a normal state in which it has not been removed.

In step S458, the electronic control unit 200 determines that the PM collecting device 50 is in the removed state.

In step S459, the electronic control unit 200 returns the integrated value IDio to the initial value of zero, and sets the executed flag Ff1 of the first removal determination process to 1. The executed flag Ff1 of the first removal determination process is returned to the initial value of 0 at the end or start of the trip.

FIG. 10 is a flowchart illustrating the details of the second removal diagnosis.

In step S51, the electronic control unit 200 performs a second precondition determination process for determining whether or not the second precondition for detecting the removal of the PM collecting device 50 by the second removal diagnosis is satisfied. implement. The details of the second precondition determination process will be described later with reference to FIG.

In step S52, the electronic control unit 200 determines whether or not the second precondition establishment flag Fp2 is set to 1. The second precondition establishment flag Fp2 is a flag set to 1 or 0 in the second precondition determination process. The initial value of the second precondition establishment flag Fp2 is set to 0, and it is determined that the second precondition for detecting the removal of the PM collecting device 50 is satisfied in the second precondition determination process. Sometimes set to 1. If the second precondition establishment flag Fp2 is set to 1, the electronic control unit 200 proceeds to the process of step S53. On the other hand, if the second precondition establishment flag Fp2 is set to 0, the electronic control unit 200 ends the current process.

In step S53, the electronic control unit 200 determines the second implementation condition for determining whether or not the second implementation condition for accurately detecting the removal of the PM collecting device 50 by the second removal diagnosis is satisfied. Carry out the process. The details of the second implementation condition determination process will be described later with reference to FIG.

In step S54, the electronic control unit 200 determines whether or not the second implementation condition establishment flag Fe2 is set to 1. The second implementation condition establishment flag Fe2 is a flag set to 1 or 0 in the second implementation condition determination process. The initial value of the second implementation condition establishment flag Fe2 is set to 0, and it is determined that the second implementation condition for accurately detecting the removal of the PM collecting device 50 in the second implementation condition determination process is satisfied. When it is set to 1, it is set to 1. If the second implementation condition establishment flag Fe2 is set to 1, the electronic control unit 200 proceeds to the process of step S55. On the other hand, if the second implementation condition establishment flag Fe2 is set to 0, the electronic control unit 200 ends the current process.

In step S55, the electronic control unit 200 performs a second removal determination process for determining whether or not the PM collection device 50 has been removed. The details of the second removal determination process will be described later with reference to FIG.

FIG. 11 is a flowchart illustrating the details of the second precondition determination process.

In step S511, the electronic control unit 200 determines whether or not the PM collection device 50 has been removed during this trip (during one trip of the vehicle) has not yet been determined. In the present embodiment, if the electronic control unit 200 has the above-mentioned first removal determination processing implemented flag Ff1 and the later-described first removal determination processing implemented flag Ff2 (see FIG. 12) 0, the current trip. It is determined that the determination as to whether or not the PM collecting device 50 has been removed has not been performed yet, and the process proceeds to step S512. On the other hand, if the electronic control unit 200 has the flag Ff1 for which the first removal determination process has been performed or the flag Ff2 for which the second removal determination process has been performed is 1, is the PM collection device 50 removed during this trip? It is determined that the determination of whether or not it has already been performed once, and the process proceeds to step S515.

In step S512, the electronic control unit 200 determines whether or not the sensors necessary for calculating the parameters used for performing the second removal determination process are not broken. In the present embodiment, the electronic control unit 200 determines whether or not the differential pressure sensor 55 has failed. For example, in the electronic control unit 200, a short-circuit failure or a disconnection failure occurs when the detected value of the differential pressure sensor 55 is equal to or higher than a predetermined upper limit side failure determination threshold value or is equal to or lower than the lower limit side failure determination threshold value. It can be determined that there is. Further, the electronic control unit 200 determines whether or not the detection value of the differential pressure sensor 55 is within a predetermined range centered on zero when the detection value of the differential pressure sensor 55 becomes zero. If the detection value of the differential pressure sensor 55 is not within the predetermined range, it can be determined that some kind of failure has occurred in the differential pressure sensor 55.

If the differential pressure sensor 55 has not failed, the electronic control unit 200 proceeds to the process of step S513. On the other hand, if the differential pressure sensor 55 fails, the electronic control unit 200 proceeds to the process of step S515 in order to prohibit the execution of the second removal determination process described later.

In step S513, the electronic control unit 200 determines whether or not the sensors used for determining whether or not the second implementation condition is satisfied in the second implementation condition determination process are not broken. In the present embodiment, the electronic control unit 200 determines whether or not the air flow meter 211 is out of order. If the air flow meter 211 has not failed, the electronic control unit 200 proceeds to the process of step S514. On the other hand, if the air flow meter 211 is out of order, the electronic control unit 200 proceeds to the process of step S515.

In step S514, the electronic control unit 200 sets the second precondition establishment flag Fp2 to 1.

In step S515, the electronic control unit 200 sets the second precondition establishment flag Fp2 to 0.

FIG. 12 is a flowchart illustrating the details of the second implementation condition determination process.

In step S531, the electronic control unit 200 determines whether or not the engine operating state is a steady state. In the present embodiment, the electronic control unit 200 is in a state where the time change rate [g / s] of the intake air flow rate Ga is a predetermined change rate (for example, 0.5 [g / s]) or less for a predetermined time (for example, 2 seconds). If the above continuation is continued, it is determined that the engine operating state is a steady state, and the process proceeds to step S532. On the other hand, if the engine operating state is not a steady state, the electronic control unit 200 proceeds to the process of step S533.

In step S532, the electronic control unit 200 sets the second implementation condition establishment flag Fe2 to 1.

In step S533, the electronic control unit 200 sets the second implementation condition establishment flag Fe2 to 0.

FIG. 13 is a flowchart illustrating the details of the second removal determination process.

In step S551, the electronic control unit 200 calculates the front-rear differential pressure Pio of the PM collecting device 50 based on the detected value of the differential pressure sensor 55.

In step S552, the electronic control unit 200 calculates the integrated value IPio (= IPio (previous value) + Pio) of the front-rear differential pressure Pio.

In step S553, the electronic control unit 200 calculates the number of samples of the front-rear differential pressure Pio used in calculating the integrated value IPio Np (= Np (previous value) + 1), that is, the number of integrated front-rear differential pressure Pio.

In step S554, the electronic control unit 200 determines whether or not the number of samples Np is a predetermined number Np_th or more. If the number of samples Np is a predetermined number Np_th or more, the electronic control unit 200 proceeds to the process of step S455. On the other hand, if the number of samples Np is less than the predetermined number Np_th, the electronic control unit 200 ends the current process.

In step S555, the electronic control unit 200 determines whether or not the integrated value IPio is equal to or greater than the predetermined threshold value Ipth. If the integrated value IPio is equal to or higher than the predetermined threshold value Ipth, the electronic control unit 200 proceeds to the process of step S556. On the other hand, if the integrated value IPio is less than the predetermined threshold value Ipth, the electronic control unit 200 proceeds to the process of step S557.

In step S556, the electronic control unit 200 determines that the PM collecting device 50 is in a normal state in which it has not been removed.

In step S557, the electronic control unit 200 determines that the PM collecting device 50 is in the removed state.

In step S558, the electronic control unit 200 returns the integrated value IPio to the initial value of zero, and sets the executed flag Ff2 of the second removal determination process to 1. The executed flag Ff2 of the second removal determination process is returned to the initial value of 0 at the end or start of the trip.

The internal combustion engine 100 according to the present embodiment described above includes the engine body 10, the PM collecting device 50 as the exhaust aftertreatment device 30 provided in the exhaust pipe 22 (exhaust passage) of the engine body 10, and the PM collecting device 50.
A first exhaust temperature sensor 53 that detects the first exhaust temperature that is the temperature of the exhaust that flows into the PM collecting device 50, and a second exhaust temperature that detects the temperature of the exhaust that flows out of the PM collecting device 50. It includes an exhaust temperature sensor 54 and a differential pressure sensor 55 that detects the front-rear differential pressure of the PM collecting device 50. The electronic control unit 200 (control device) that controls the internal combustion engine 100 includes a time change rate calculation unit that calculates a time change rate Ain of the first exhaust temperature and a time change rate Aout of the second exhaust temperature, and a first exhaust temperature. Based on the difference between the time change rate Ain and the time change rate Aout of the second exhaust temperature, the first determination unit for determining whether or not the PM collecting device 50 is in the removed state removed from the exhaust pipe 22. A second determination unit for determining whether or not the vehicle is in the removed state based on the front-rear differential pressure Pio is provided.

When the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 is out of order, the electronic control unit 200 prohibits the first determination unit from determining whether or not the first exhaust temperature sensor 53 is in the removed state, and the differential pressure sensor 55. When is out of order, it is configured to prohibit the second determination unit from determining whether or not it is in the removed state.

As a result, even if the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 fails and the first removal determination process (determination of whether or not the removal state is achieved by the first determination unit) cannot be performed, the difference is A second removal determination process (determination of whether or not the removal state is achieved by the second determination unit) using the pressure sensor 55 can be performed. On the contrary, even if the differential pressure sensor 55 fails and the second removal determination process cannot be performed, the first removal determination process using the first exhaust temperature sensor 53 or the second exhaust temperature sensor 54 can be performed. Therefore, even if any of the first exhaust temperature sensor 53, the second exhaust temperature sensor 54, or the differential pressure sensor 55 fails, either the first removal determination process or the second removal determination process can be performed. , It is possible to suppress the inability to determine whether or not the product is in the removed state.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, the first removal diagnosis is performed when the exhaust flow rate Ge is less than the predetermined flow rate, and the second removal diagnosis is performed when the exhaust flow rate Ge is equal to or more than the predetermined flow rate. Is different from. Hereinafter, the differences will be mainly described.

FIG. 14 is a flowchart illustrating the removal diagnosis of the PM collecting device 50 according to the present embodiment. Note that, in FIG. 14, the processing contents other than step S201 are the same as the processing contents of the first embodiment described above, and thus the description thereof will be omitted here.

In step S201, the electronic control unit 200 determines whether or not the exhaust flow rate Ge is less than a predetermined fourth flow rate Ge_th4 (for example, 35 [g / s]). If the exhaust flow rate Ge is less than the fourth flow rate Ge_th4, the electronic control unit 200 proceeds to the process of step S4. On the other hand, if the exhaust flow rate Ge is the fourth flow rate Ge_th4 or more, the electronic control unit 200 proceeds to the process of step S5.

As in the present embodiment described above, it is simply determined whether to perform the first removal diagnosis or the second removal diagnosis depending on whether the exhaust flow rate Ge is less than the fourth flow rate Ge_th4. You may do so.

(Third Embodiment)
Next, a third embodiment of the present invention will be described. In this embodiment, the contents of the first removal determination process and the second removal determination process are different from those of the first embodiment. Specifically, in the first removal determination process, it is determined whether or not the removal state is achieved by comparing the average value ADio of the difference value Dio with the predetermined threshold value ADth, and in the second removal determination process, the front-back difference is obtained. It differs from the first embodiment in that it is determined whether or not the product is in the removed state by comparing the average value APio of the pressure Pio with the predetermined threshold value APth. Hereinafter, this difference will be mainly described.

FIG. 15 is a flowchart illustrating the details of the first removal determination process according to the present embodiment. In FIG. 15, the contents of the processes from step S451 to step S455 and from steps S457 to 459 are the same as the contents of the processes described in the first embodiment, and thus the description thereof will be omitted here.

In step S301, the electronic control unit 200 calculates the average value ADio of the difference value Dio by dividing the integrated value IDio by the number of samples Ni of the difference value Dio used in calculating the integrated value Dio, and this average. It is determined whether or not the value ADio is equal to or greater than the predetermined threshold value ADth. If the average value ADio is equal to or higher than the predetermined threshold value ADth, the electronic control unit 200 proceeds to the process of step S457. On the other hand, if the average value ADio is less than the predetermined threshold value ADth, the electronic control unit 200 proceeds to the process of step S458.

FIG. 16 is a flowchart illustrating the details of the second removal determination process according to the present embodiment. In FIG. 16, the contents of the processes from step S551 to step S554 and steps S556 to 558 are the same as the contents of the processes described in the first embodiment, and thus the description thereof will be omitted here.

In step S302, the electronic control unit 200 calculates the average value APio of the front-rear differential pressure Pio by dividing the integrated value IPio by the number of samples Np of the front-rear differential pressure Pio used in calculating the integrated value IPio. It is determined whether or not the average value APio is equal to or higher than the predetermined threshold value APth. If the average value APio is equal to or higher than the predetermined threshold value APth, the electronic control unit 200 proceeds to the process of step S556. On the other hand, if the average value APio is less than the predetermined threshold value APth, the electronic control unit 200 proceeds to the process of step S557.

As in the present embodiment described above, in the first removal determination process, the difference value Dio between the absolute value of the time change rate Ain of the first exhaust temperature and the absolute value of the time change rate Aout of the second exhaust temperature. Even if the average value ADio of a certain number or more is calculated and if the average value ADio is less than the predetermined threshold value ADth, it is determined that the product is in the removed state, the same effect as that of the first embodiment can be obtained. Further, in the second removal determination process, even if the average value APio of one constant or more of the front-rear differential pressure Pio is calculated and if the average value APio is less than the predetermined threshold value APth, it is determined that the removal state is achieved. The same effect as the morphology can be obtained.

(Fourth Embodiment)
Next, a fourth embodiment of the present invention will be described. In this embodiment, the mounting position of the first exhaust temperature sensor 53 is different from that in the first embodiment. Hereinafter, the differences will be mainly described.

FIG. 17 is a schematic configuration diagram of an internal combustion engine 100 according to a fourth embodiment of the present invention and an electronic control unit 200 for controlling the internal combustion engine 100.

As shown in FIG. 17, in the present embodiment, the first exhaust temperature sensor 53 is located upstream of the PM collecting device 50 in the exhaust flow direction and PM collecting due to the above-mentioned problems of mounting space and heat resistance. It is attached to the exhaust pipe 22 at a position away from the inlet of the collector 50. In such a case, if the distance from the first exhaust temperature sensor 53 to the inlet of the PM collecting device 50 is long, the removed state using the temperature change rate Ain of the first exhaust temperature detected by the first exhaust temperature sensor 53. There is a risk that the judgment accuracy will be reduced when the judgment is made.

Therefore, in such a case, the estimated exhaust temperature near the inlet of the PM collecting device 50 (hereinafter referred to as “estimated first exhaust temperature”) is calculated and estimated based on the detected value of the first exhaust temperature sensor 53. It may be preferable to use the temperature change rate Ain of the first exhaust temperature to determine whether or not it is in the removed state as in the first embodiment. Therefore, in the present embodiment, it is decided to calculate the estimated first exhaust temperature based on the detected value of the first exhaust temperature sensor 53.

FIG. 18 is a flowchart illustrating an estimation control for calculating an estimated first exhaust temperature based on a first exhaust temperature sensor 53 attached to an exhaust pipe 22 at a position away from the inlet of the PM collecting device 50.

In step S401, the electronic control unit 200 reads the detected value of the first exhaust temperature sensor 53.

In step S402, the electronic control unit 200 refers to the map of FIG. 19 created in advance by experiments or the like, and is a PM collecting device from the first exhaust temperature sensor 53 based on the intake air flow rate Ga and the outside air temperature. The amount of temperature decrease of the exhaust gas that decreases in the process of flowing through the exhaust pipe 22 up to 50 is calculated. As shown in the map of FIG. 19, the amount of decrease in the temperature of the exhaust tends to increase as the intake air flow rate Ga is smaller and the exhaust temperature is lower.

In step S403, the electronic control unit 200 performs a delay process such as a primary delay process on the amount of temperature decrease of the exhaust gas. Such delay processing is performed to some extent until the detected value of the first exhaust temperature sensor 53 actually changes to a value corresponding to the exhaust temperature of the exhaust passing near the first exhaust temperature sensor 53. Therefore, the response speed of the first exhaust temperature sensor 53 is taken into consideration.

In step S404, the electronic control unit 200 calculates an estimated first exhaust temperature obtained by subtracting the amount of temperature decrease of the delayed exhaust from the exhaust temperature corresponding to the detection value of the first exhaust temperature sensor 53. ..

According to the present embodiment described above, when the distance from the first exhaust temperature sensor 53 to the inlet of the PM collecting device 50 is long, it is possible to suppress the deterioration of the determination accuracy of whether or not the exhaust gas is in the removed state. Can be done.

(Fifth Embodiment)
Next, a fifth embodiment of the present invention will be described. In this embodiment, the content of the first embodiment condition determination process is different from that of the first embodiment. Hereinafter, the differences will be mainly described.

FIG. 20 is a flowchart illustrating the details of the first implementation condition determination process according to the present embodiment. In FIG. 20, the contents of the processes from step S431 to step S434 are the same as the contents of the processes described in the first embodiment, and thus the description thereof will be omitted here.

In step S501, the electronic control unit 200 determines whether or not the first exhaust temperature is in a state of being lowered, for example, during steady running or deceleration of the vehicle. The reason for making such a judgment is that the temperature change of the second exhaust temperature tends to be slower when the temperature drops than when the temperature of the first exhaust temperature rises. This is because the difference value Dio tends to be large. That is, it is possible to more accurately detect whether or not the PM collecting device 50 is in the removed state when the temperature is lowered as compared with when the temperature of the first exhaust temperature is raised.

In the present embodiment, in step S501, whether or not the time change rate Ain of the first exhaust temperature is equal to or less than the predetermined change rate Ain_th (negative value, for example, −5 [° C./s]). To judge. Then, if the time change rate Ain of the first exhaust temperature is equal to or less than the predetermined change rate Ain_th, the electronic control unit 200 determines that the first exhaust temperature is in a lowered state, and proceeds to the process of step S433. On the other hand, if the time change rate Ain of the first exhaust temperature is less than the predetermined change rate Ain_th, the electronic control unit 200 proceeds to the process of step S434.

According to the present embodiment described above, since the first removal diagnosis using the first exhaust temperature sensor 53 and the second exhaust temperature sensor 54 is performed when the temperature of the first exhaust temperature drops, whether or not it is in the removed state. The determination accuracy can be further improved.

(Sixth Embodiment)
Next, a sixth embodiment of the present invention will be described. In this embodiment, the content of the first embodiment condition determination process is different from each of the above-described embodiments. Hereinafter, the differences will be mainly described.

As in the fifth embodiment described above, as the first implementation condition for determining whether or not the vehicle is in the removed state, the exhaust flow rate Ge is equal to or higher than the first flow rate Ge_th1, and the first exhaust temperature is lowered. In addition to the fact that the condition is (the time change rate Ain of the first exhaust temperature is equal to or less than the predetermined change rate Ain_th), the internal combustion engine 100 is started and stopped multiple times during one trip. In the case of a certain vehicle (hereinafter referred to as "vehicle that implements intermittent engine operation"), the following problems may occur.

Examples of the vehicle for performing intermittent engine operation include a vehicle having an idle stop function (that is, a vehicle in which idle stop control is performed by the electronic control unit 200 as control of the internal combustion engine 100) and as shown in FIG. 21. An EV mode (a mode in which the vehicle travels with the power of the traveling motor 300) and an HV mode (a mode in which the vehicle travels with the power of the traveling motor 300) and an HV mode (a mode in which the traveling motor 300 is powered in addition to the power of the traveling motor 300 according to the required torque of the vehicle) are provided as a vehicle drive source in addition to the internal combustion engine 100. Examples include hybrid vehicles in which switching control with (mode of traveling using power) is performed.

The idle stop control is a control that automatically stops the internal combustion engine 100 when the preset engine stop condition is satisfied, and automatically restarts the internal combustion engine 100 when the preset engine restart condition is satisfied. .. The engine stop conditions are, for example, that the speed (vehicle speed) of the own vehicle is 0 [km / h], that the brake pedal is depressed (that is, the amount of brake depression is a certain amount or more), and that the accelerator pedal is It may be that the vehicle has not been depressed (that is, the accelerator depression amount is zero), the battery charge amount is equal to or higher than the predetermined amount, and the like. Further, as the engine restart condition, for example, the brake pedal is not depressed (that is, the brake depression amount is zero), the shift lever is in the drive range (for example, the D range or the R range), and the like.

Further, in the following description, a vehicle that operates the internal combustion engine 100 without stopping during one trip is referred to as a "normal vehicle" in order to distinguish it from a vehicle that implements intermittent engine operation.

FIG. 22A is a time chart showing temperature changes of the first exhaust temperature and the second exhaust temperature when the internal combustion engine 100 is operated in a normal state in which the PM collecting device 50 is not removed in a normal vehicle. .. FIG. 22B shows temperature changes of the first exhaust temperature and the second exhaust temperature when the internal combustion engine 100 is operated in a normal state in which the PM collecting device 50 is not removed in the hybrid vehicle as the engine intermittent operation implementation vehicle. It is a time chart showing.

As shown in FIG. 22A, in the case of a normal vehicle, the internal combustion engine 100 is not stopped even if the vehicle required torque decreases during steady running or deceleration after acceleration, so that the vehicle required torque decreases. Along with this, the intake air flow rate Ga and eventually the exhaust flow rate Ge decrease, and at the same time, the first exhaust temperature decreases. Therefore, in the case of a normal vehicle, the exhaust flow rate Ge is within a predetermined range (between the first flow rate Ge_th1 and the second flow rate Ge_th2) in a state where the first exhaust temperature is lowered during steady driving or deceleration. The first implementation condition is satisfied.

On the other hand, as shown in FIG. 22B, in the case of a hybrid vehicle, after accelerating by the power of the internal combustion engine 100 and the traveling motor 300, the vehicle required torque decreases during steady running or deceleration, and the vehicle required torque becomes higher. When the torque becomes less than the predetermined torque, the internal combustion engine 100 is temporarily stopped. Therefore, in the case of a hybrid vehicle, the internal combustion engine 100 is temporarily stopped and the exhaust flow rate Ge becomes zero and becomes less than the first flow rate Ge_th1 during steady driving or deceleration when the first exhaust temperature tends to decrease. Therefore, the frequency with which the first implementation condition is satisfied is reduced as compared with the case of a normal vehicle. Therefore, in the case of a hybrid vehicle, it is not suitable to add that the first exhaust temperature is lowered as the first implementation condition.

Here, as shown in FIG. 22A, in the case of a normal vehicle, the internal combustion engine 100 is in an idle operation state even when the vehicle is stopped, so that exhaust gas is discharged from the engine body 10. Therefore, in the case of a normal vehicle, the first exhaust temperature and the second exhaust temperature gradually decrease even when the vehicle is stopped.

On the other hand, as shown in FIG. 22B, in the case of a hybrid vehicle, the internal combustion engine 100 remains stopped even when the vehicle is stopped, and exhaust gas is not discharged from the engine body 10, so that heat is dissipated from the exhaust pipe 22. , The first exhaust temperature and the second exhaust temperature are significantly lower than those of a normal vehicle. Therefore, in the case of a hybrid vehicle, when accelerating after restarting, the first exhaust temperature rises significantly from the lowered state. That is, in the case of a hybrid vehicle, the time change rate Ain of the first exhaust temperature becomes larger during acceleration after restarting as compared with a normal vehicle. Similarly, in a vehicle having an idle stop function, the internal combustion engine 100 is stopped when the vehicle is stopped, so that the time change rate Ain of the first exhaust temperature becomes large when accelerating after restarting.

In this way, in the case of a vehicle carrying out intermittent engine operation, the time change rate Ain of the first exhaust temperature tends to increase when accelerating after restarting, and the time change rate Ain of the first exhaust temperature tends to increase when accelerating after restarting. A difference is likely to occur between the second exhaust temperature and the time change rate Aout of the second exhaust temperature. Therefore, in the case of a vehicle in which engine intermittent operation is carried out, the time of acceleration after restarting is suitable as the first implementation condition for determining whether or not the vehicle is in the removed state.

Therefore, in the case of a vehicle for which engine intermittent operation is carried out, the content of the first implementation condition determination process is changed so that it is determined whether or not the vehicle is in the removed state when accelerating after restarting.

FIG. 23 is a flowchart illustrating the details of the first implementation condition determination process according to the present embodiment. In FIG. 23, the contents of the processes of steps S433 and S434 are the same as the contents of the processes described in the first embodiment, and thus the description thereof will be omitted here.

In step S601, in the electronic control unit 200, the time Ts in which the internal combustion engine 100 is stopped (hereinafter referred to as “engine stop time”) Ts before the internal combustion engine 100 is started (including restarting) is first. It is determined whether or not the predetermined time is Ts_th (for example, 10 seconds) or more. If the engine stop time Ts is equal to or longer than the first predetermined time Ts_th, the electronic control unit 200 proceeds to the process of step S602. On the other hand, if the engine stop time Ts is less than the first predetermined time Ts_th, the electronic control unit 200 proceeds to the process of step S35.

Such a determination is made because when the engine stop time is short, the decrease in the first exhaust temperature is small, and as a result, the increase in the first exhaust temperature during acceleration after the engine is started is also small. At the time of subsequent acceleration, the difference between the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature is less likely to occur, and the accuracy of determining whether or not the exhaust state is removed may decrease. Because.

In step S602, the electronic control unit 200 has a second predetermined time To_th (for example, 3 seconds) in which the elapsed time (hereinafter referred to as “elapsed time after starting”) To after the internal combustion engine 100 is started (including restarting) is ) Determine if it is above or not. The reason for making such a determination is that there is a certain time delay between the start of the internal combustion engine 100 and the rise of the first exhaust temperature. If the elapsed time To after the start of the electronic control unit 200 is the second predetermined time To_th or more, the electronic control unit 200 proceeds to the process of step S602. On the other hand, if the elapsed time To after the start is less than the second predetermined time To_th, the electronic control unit 200 proceeds to the process of step S434.

In step S603, the electronic control unit 200 determines whether or not the exhaust flow rate Ge is equal to or higher than a predetermined fifth flow rate Ge_th5 (for example, 18 [g / s]). If the exhaust flow rate Ge is equal to or higher than the fifth flow rate Ge_th5, the electronic control unit 200 proceeds to the process of step S604. On the other hand, if the exhaust flow rate Ge is less than the fifth flow rate Ge_th5, the electronic control unit 200 proceeds to the process of step S434.

The reason for making such a determination is as follows. That is, the temperature of the exhaust gas discharged from the engine body 10 basically tends to increase as the engine load increases, in other words, as the intake air flow rate Ga, and eventually the exhaust flow rate Ge, increases. Therefore, as the exhaust flow rate Ge increases, the increase range of the first exhaust temperature at the time of acceleration after starting the engine also increases, and the time change rate Ain of the first exhaust temperature also increases. Conversely, when the engine load is low and the exhaust flow rate Ge is small, the rise in the first exhaust temperature is small and the time change rate Ain of the first exhaust temperature is small, so that the time change rate of the first exhaust temperature is small. The difference between Ain and the time change rate Aout of the second exhaust temperature is less likely to occur. Therefore, the accuracy of determining whether or not the device is in the removed state may decrease. Therefore, in the present embodiment, whether or not the exhaust flow rate Ge is the fifth flow rate Ge_th5 or more, that is, whether or not the engine load is a constant load or more (whether or not the acceleration is a constant acceleration or more on a flat road). Is being judged.

In step S604, the electronic control unit 200 determines whether or not the temperature of the PM collecting device 50 is equal to or lower than a predetermined temperature (for example, 380 [° C.]). In the present embodiment, the electronic control unit 200 regards the second exhaust temperature as the temperature of the PM collecting device 50 and determines whether or not the second exhaust temperature is equal to or lower than the predetermined temperature. If the second exhaust temperature is equal to or lower than the predetermined temperature, the electronic control unit 200 proceeds to the process of step S605. On the other hand, if the second exhaust temperature is higher than the predetermined temperature, the electronic control unit 200 proceeds to the process of step S434.

The reason for making such a determination is as follows. That is, the lower the temperature of the PM collecting device 50, the lower the exhaust temperature in the process of passing through the PM collecting device 50. Therefore, the second is compared with the temperature change rate (temperature rise rate) Ain of the first exhaust temperature. The temperature change rate (temperature rise rate) Aout of the exhaust temperature tends to be small. Therefore, the lower the temperature of the PM collecting device 50, the more likely it is that a difference will occur between the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature when accelerating after starting the engine, and the state is removed. This is because it is possible to accurately determine whether or not it is.

In step S605, the electronic control unit 200 determines whether or not the first implementation condition establishment flag Fe1 is set to 0. If the first implementation condition establishment flag Fe1 is set to 0, the electronic control unit 200 proceeds to the process of step S433. On the other hand, if the first implementation condition establishment flag Fe1 is set to 1, the electronic control unit 200 proceeds to the process of step S606.

In step S606, the electronic control unit 200 determines whether or not the integrated value IGa of the intake air flow rate Ga after starting the internal combustion engine 100 is a predetermined second integrated value IGa_th2 (for example, 150 [g]) or less. do. If the integrated value IGa is equal to or less than the second integrated value IGa_th2, the electronic control unit 200 proceeds to the process of step S433. On the other hand, if the integrated value IGa is larger than the second integrated value IGa_th2, the electronic control unit 200 proceeds to the process of step S434.

The reason for making such a determination is as follows.

When each condition from step S601 to step S605 is satisfied and the first implementation condition establishment flag Fe1 is set to 1 in step S34, the first removal determination process is executed, but the first removal determination process is performed at the time of acceleration after the engine is started. 1 Time change rate (temperature rise rate) of exhaust temperature Ain gradually decreases as the first exhaust temperature increases during acceleration. That is, when the total heat amount of the exhaust gas from the start of acceleration exceeds a certain amount, the time change rate (temperature rise rate) Ain of the first exhaust gas temperature gradually decreases.

Here, the total heat amount of the exhaust gas is proportional to the exhaust gas amount from the start of acceleration, that is, the integrated value IGa of the intake air flow rate Ga. Therefore, when the integrated value IGa of the intake air flow rate Ga after starting the internal combustion engine 100 becomes larger than the second integrated value IGa_th2, the time change rate Ain of the first exhaust temperature becomes smaller, so that the time of the first exhaust temperature The difference between the rate of change Ain and the rate of time change Aout of the second exhaust temperature is less likely to occur, and the accuracy of determining whether or not the exhaust state is removed may decrease. Therefore, in the present embodiment, when the first implementation condition establishment flag Fe1 is set to 1 and the first removal determination process is being performed, is the integrated value IGa of the intake air flow rate Ga equal to or less than the second integrated value IGa_th2? It is trying to judge whether or not it is.

According to the present embodiment described above, when the internal combustion engine 100 is started after the first exhaust temperature drops while the engine is stopped and the engine load exceeds a certain level (when accelerating), that is, the first. When the time change rate Ain of the exhaust temperature becomes large, it is possible to determine whether or not the exhaust state is in the removed state. Therefore, a difference is likely to occur between the time change rate Ain of the first exhaust temperature and the time change rate Aout of the second exhaust temperature, and it is possible to improve the determination accuracy of whether or not it is in the removed state.

Although the embodiments of the present invention have been described above, the above-described embodiments show only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above-described embodiments. not.

For example, in each of the above embodiments, it was detected that the PM collecting device 50 as the exhaust aftertreatment device 30 was removed, but for example, it is detected that the catalyst device 40 has been removed by the same method. You may do it. That is, the removal of the device having a certain heat capacity attached to the exhaust pipe 22 may be detected by the method described in each of the above embodiments.

10 Engine body 22 Exhaust pipe (exhaust passage)
50 PM collection device (exhaust gas aftertreatment device)
53 1st exhaust temperature sensor 54 2nd exhaust temperature sensor 55 Differential pressure sensor 100 Internal combustion engine 200 Electronic control unit (control device)

Claims (1)

With the main body of the engine
The exhaust aftertreatment device provided in the exhaust passage of the engine body and
A first exhaust temperature sensor that detects the first exhaust temperature, which is the temperature of the exhaust flowing into the exhaust aftertreatment device, and
A second exhaust temperature sensor that detects the second exhaust temperature, which is the temperature of the exhaust discharged from the exhaust aftertreatment device, and
A differential pressure sensor that detects the front-rear differential pressure of the exhaust aftertreatment device, and
An internal combustion engine control device for controlling an internal combustion engine.
A time change rate calculation unit that calculates the time change rate of the first exhaust temperature and the time change rate of the second exhaust temperature.
Based on the difference between the time change rate of the first exhaust temperature and the time change rate of the second exhaust temperature, it is determined whether or not the exhaust aftertreatment device is in the removed state removed from the exhaust passage. 1 Judgment unit and
A second determination unit that determines whether or not the product is in the removed state based on the front-rear differential pressure,
Equipped with
When the first exhaust temperature sensor or the second exhaust temperature sensor is out of order, the first determination unit prohibits the determination of whether or not it is in the removed state, and the differential pressure sensor is out of order. When, the determination of whether or not the removal state is performed by the second determination unit is prohibited.
Internal combustion engine control device.

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