JP2018071489A - Internal combustion engine control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which can detect a state of an internal combustion engine with high reliability and high accuracy.SOLUTION: An internal combustion engine control device for controlling an internal combustion engine having a constitution which separates a part of exhaust emission from a cylinder, cools it by a cooler, mixes it with intake air via an exhaust recirculation valve, and supplies the mixed air to the cylinder has: a first differential pressure sensor which is arranged while straddling the exhaust recirculation valve, and detects a difference between the pressure of a front stage and the pressure of a rear stage of the exhaust recirculation valve as recirculation valve differential pressure; a control part for controlling the exhaust recirculation valve; and a diagnosis execution part which makes the control part close the exhaust recirculation valve, and determines a state of the internal combustion engine on the basis of the recirculation valve differential pressure which is detected by the first differential pressure sensor in that state.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for controlling an internal combustion engine.

  Patent Document 1 states that “the control device for an internal combustion engine of the present invention detects the pressure difference between the upstream and downstream of the low-pressure EGR control valve with a differential pressure detection device, and based on this, the operation of the EGR control valve and the operation of the intake throttle valve The differential pressure measuring device controls the pressure in the first region portion between the intake throttle valve and the EGR control valve and the second region portion upstream from the EGR control valve when the intake throttle valve is in a fully inoperative state. When a difference is detected and the intake throttle valve is in an operating state, the upstream and downstream of the EGR control valve based on the pressure difference between the second region and the third region downstream from the second region and upstream from the EGR control valve Is detected ”. Thereby, it is considered that the intake side pressure can be detected.

Japanese Patent Laying-Open No. 2015-121167

  In the technique described in Patent Document 1, a differential pressure sensor is attached so as to straddle the intercooler upstream of the EGR valve, and the pressure on the intake side is calculated based on the pressure difference detected by the differential pressure sensor. Since the upstream of the intercooler is hot, the reliability of the differential pressure sensor becomes a problem, and the differential pressure sensor is required to have high heat resistance. In Patent Document 1, the pressure on the intake side is not directly measured, but the pressure on the intake side is estimated using a physical model. Therefore, the accuracy of pressure detection may be insufficient due to the accuracy of the physical model.

  An object of the present invention is to provide a technique that makes it possible to detect the state of an internal combustion engine with high reliability and high accuracy.

  An internal combustion engine control apparatus according to one aspect of the present invention is an internal combustion engine configured to separate a part of exhaust from a cylinder, cool it with a cooler, mix it with intake air via an exhaust recirculation valve, and supply the mixture to the cylinder An internal combustion engine control apparatus for controlling an engine, wherein the first difference is installed across the exhaust gas recirculation valve and detects a difference between a pressure at a front stage and a pressure at a rear stage of the exhaust gas recirculation valve as a recirculation valve differential pressure. A pressure sensor, a control unit that controls the exhaust gas recirculation valve, and the control unit that closes the exhaust gas recirculation valve, and in this state, based on the recirculation valve differential pressure detected by the first differential pressure sensor And a diagnosis execution unit for determining the state of the internal combustion engine.

  According to the present invention, the first differential pressure sensor is installed on the exhaust gas recirculation path after cooling so as to straddle the exhaust gas recirculation valve, and the differential pressure before and after the exhaust gas recirculation valve is measured by the first differential pressure sensor. Based on this, since the state of the path including the exhaust path is determined, it is possible to determine the state of the path including the high temperature portion while reducing the influence of the heat of the high temperature portion on the first differential pressure sensor.

1 is a configuration diagram of an internal combustion engine according to Embodiment 1. FIG. 2 is a block diagram of an internal combustion engine control device 115. FIG. 3 is a flowchart showing an operation of detecting the exhaust pressure of the internal combustion engine control device 115. 6 is a flowchart showing an operation of the internal combustion engine control device 115 in the second embodiment. 10 is a flowchart showing the operation of the internal combustion engine control device 115 in the third embodiment. FIG. 10 is a block diagram of an internal combustion engine control device 115 according to a fourth embodiment. 10 is a flowchart showing the operation of the internal combustion engine control device 115 in the fourth embodiment. 10 is a flowchart showing an operation of the internal combustion engine control device 115 in the fifth embodiment. 6 is a diagram showing the relationship between the flow rate of exhaust gas passing through an EGR valve 112 and the flow rate of fresh air sucked through the air cleaner 118. FIG.

<Embodiment 1>
FIG. 1 is a configuration diagram of an internal combustion engine according to the first embodiment. The internal combustion engine according to the first embodiment is provided with an exhaust gas recirculation (Exhaust Gas Recirculation) device. In the following, exhaust gas recirculation may be simply referred to as EGR. In the present embodiment, an internal combustion engine 106 having an external EGR mechanism will be described in particular. However, the present invention is not limited to this, and the present invention can be similarly applied to other EGR mechanisms.

  A turbocharger 108 and a pre-catalyst 109 are installed in the piping of the exhaust path 119 of the internal combustion engine 106. The turbocharger 108 is composed of a turbine that rotates in response to an exhaust flow, a shaft that transmits the rotation of the turbine, and a compressor that takes in and compresses air using the torque of the turbine, and compresses using the exhaust flow. This is a supercharger that drives the machine to increase the density of the air taken in by the internal combustion engine 106.

  Exhaust gas from the internal combustion engine 106 is purified by reduction and oxidation in the pre-catalyst 109 and the main catalyst 113. Particulate matter that cannot be purified by the pre-catalyst 109 and the main catalyst 113 is purified by GPF 114 (Gasoline Particulate Filter).

  Part of the exhaust gas purified by the pre-catalyst 109 is taken into the EGR pipe 120 from the downstream of the pre-catalyst 109, cooled by the intercooler 110, and returned to the upstream of the turbocharger 108. The upstream of the turbocharger 108 is a portion where gas flows into the turbocharger 108. A part of the combustion gas generated in the cylinder 102 of the internal combustion engine 106 is recirculated to the intake pipe 116 via the EGR pipe 120 and mixed with the intake air newly sucked from the outside via the air cleaner 118.

  The air cleaner 118 removes dust and the like contained in fresh air to be sucked. The flow rate of the exhaust gas (EGR) recirculated through the EGR pipe 120 is determined by controlling the opening degree of the EGR valve 112. By controlling the EGR, it is possible to reduce the pumping loss while lowering the combustion temperature of the air-fuel mixture in the cylinder 102 to reduce the NOx emission amount.

  The internal combustion engine 106 is controlled by the internal combustion engine control device 115. The air flow sensor 101 detects the flow rate of fresh air that is newly sucked from the outside. Although not shown, a pressure sensor is attached between the turbocharger 108 and the cylinder 102 to detect the pressure of air in the intake pipe 104 that intakes the cylinder 102 or the intake chamber 104 downstream of the intake throttle valve 103. The flow rate of the mixed gas flowing from the intake pipe 116 to the cylinder 102 is controlled by a variable phase valve timing mechanism 117 that changes the opening degree of the intake throttle valve 103 and the opening / closing timing of the intake valve or the exhaust valve.

  The internal combustion engine control device 115 of the present embodiment controls the actuator so as to achieve the target EGR rate based on the detection value of the pressure sensor, the opening of the intake throttle valve 103, or the detection value of the air flow sensor 101. To do.

  In the present embodiment, the EGR rate refers to the ratio of fresh air to exhaust in the mixed gas flowing through the intake pipe 116. The internal combustion engine control device 115 detects a difference (differential pressure) between the pressure at the front stage and the pressure at the rear stage of the EGR valve 112 by a differential pressure sensor 111 attached so as to straddle the EGR valve 112, and based on that, the EGR valve 112 and The opening degree of the intake throttle valve 103 or the phase angle of the intake / exhaust valve is set by the variable phase valve timing mechanism 117, and the EGR rate of the mixed gas flowing in through the intercooler 110 is controlled. Further, the internal combustion engine control device 115 optimally controls the ignition timing of the spark plug 105 so as not to cause knocking and to maximize the output of the internal combustion engine 106.

  FIG. 2 is a block diagram of the internal combustion engine control device 115. In other words, the internal combustion engine control device 115 includes a detection unit 202, a travel distance detection unit 203, a diagnosis determination unit 205, a diagnosis execution unit 201, a diagnosis notification unit 207, and an actuator control unit 208. The actuator control unit 208 includes an EGR valve control unit 209 and a filter regeneration unit 210.

  That is, the detection unit 202 detects clogging of the GPF 114, the air cleaner 118, or the intercooler 110 based on the output from each sensor 204. The sensor 204 includes a differential pressure sensor 111.

  The travel distance detection unit 203 detects the travel distance of the vehicle on which the internal combustion engine 106 is mounted. The diagnosis determination unit 205 acquires these detection results, and whether to permit learning of control parameters of each functional unit (for example, the EGR valve 112) included in the internal combustion engine 106 based on the detection results, or the GPF 114 Then, it is determined whether or not the diagnosis of the air cleaner 118 and the intercooler 110 is permitted. The diagnosis execution unit 201 performs the learning or diagnosis, and stores the result in the storage device 213. The diagnosis notification unit 207 notifies the driver that learning or diagnosis is being performed.

  The EGR valve control unit 209 reflects the detection result of each sensor 204 in the diagnosis for the EGR valve 112. Each sensor 204 is a differential pressure sensor 111, an air flow rate sensor 101, a rotation speed sensor 107, and other sensors (not shown) attached to the internal combustion engine 106, and can detect pressure, air flow rate, rotation speed, and the like. . The filter regeneration unit 210 regenerates the GPF 114 based on the detection result of each sensor 204, and further updates the regeneration time as necessary.

  The diagnosis notification unit 207 acquires a state indicating whether learning or diagnosis is being performed from the diagnosis execution unit 201 and notifies the state to the outside of the vehicle via the notification unit 211. For example, a warning lamp provided in a driver room (not shown) is turned on.

  FIG. 3 is a flowchart showing an operation of detecting the exhaust pressure of the internal combustion engine control device 115. The internal combustion engine control device 115 repeatedly executes the flowchart of FIG. 3 in a predetermined program cycle. Hereinafter, each step of FIG. 3 will be described.

Step S301
The internal combustion engine control device 115 detects the rotational speed and the intake air amount of the internal combustion engine 106 by the rotational speed sensor 107 and the air flow rate sensor 101, and determines the operating state of the internal combustion engine 106 based on the rotational speed and the intake air amount. . The internal combustion engine control device 115 determines whether or not to allow the passage of exhaust gas through the EGR valve 112 to be stopped for diagnosis based on the information on the operating state by the diagnosis determination unit 205. If permitted, the process proceeds to step S302. If not permitted, the process returns to step S301.

Step S302
When it is permitted to stop the flow rate of the EGR valve 112, the diagnosis execution unit 201 of the internal combustion engine control device 115 instructs the EGR valve control unit 209 to close the EGR valve 112 until it is fully closed.

Step S303
The EGR valve control unit 209 detects whether or not the EGR valve 112 is closed based on the detection result of the opening degree of the EGR valve 112 from an opening degree sensor of the EGR valve 112 (not shown in the present embodiment). When the EGR valve 112 is closed, the process proceeds to S304, and when it is not closed, the process returns to step S303.

Step S304
When it is detected that the EGR valve 112 is closed, the diagnosis execution unit 201 uses the differential pressure sensor 111 to calculate a difference in pressure before and after the EGR valve 112 (differential pressure). The diagnosis execution unit 201 determines the state of the internal combustion engine 106 based on the differential pressure (recirculation valve differential pressure) detected by the differential pressure sensor 111. The actuator control unit 208 determines the opening / closing and opening of the EGR valve 112 according to the operating state of the internal combustion engine 106. Thereby, control of the EGR valve 112 suitable for the operating state of the internal combustion engine 106 can be performed, and the utility of the control can be enhanced.

  According to the present embodiment, the differential pressure sensor 111 is installed so as to straddle the exhaust gas recirculation valve (EGR valve) 112 in the exhaust gas recirculation path (EGR pipe) 120 after cooling, and the exhaust gas measured by the differential pressure sensor 111. Since the state of the internal combustion engine 106 including the exhaust path 119 is determined based on the differential pressure before and after the recirculation valve 112, the internal combustion engine including the high temperature portion is reduced while reducing the influence of the heat of the high temperature portion on the differential pressure sensor 111. The state of the engine 106 can be determined.

  Further, according to the present embodiment, the heat resistance performance required for the differential pressure sensor 111 is alleviated and the reliability is improved. Since the differential pressure sensor 111 can be used at a stable temperature, the measurement accuracy of the differential pressure is increased.

  Further, the internal combustion engine control apparatus 115 according to the first embodiment is configured so that the static pressure upstream of the EGR valve 112 and the static pressure downstream of the EGR valve 112 are based on the differential pressure measured by the differential pressure sensor 111 with the EGR valve 112 closed. Both can be calculated. The upstream of the EGR valve 112 is a portion where gas flows into the EGR valve 112. The downstream of the EGR valve 112 is a portion where gas flows out from the EGR valve 112.

  Thereby, both the intake pressure and the exhaust pressure of the internal combustion engine 106 can be known. Both intake pressure and exhaust pressure can be calculated without providing separate pressure sensors on the intake side and the exhaust side. Therefore, the utility of the control of the internal combustion engine 106 can be enhanced while suppressing the cost.

  Further, according to the present embodiment, the differential pressure detected by the differential pressure sensor 111 increases when the filter (GPF) 114 is clogged, and decreases when the cooler (intercooler) 110 is clogged. Can be detected individually.

<Embodiment 2>
The internal combustion engine control device 115 according to the second embodiment can diagnose clogging of the GPF 114 in addition to the functions provided in the first embodiment. The internal combustion engine 106 of the second embodiment has the same configuration as that shown in FIG. 1, and the internal combustion engine control device 115 of the second embodiment has the same configuration as that shown in FIG.

  FIG. 4 is a flowchart showing the operation of the internal combustion engine control device 115 according to the second embodiment. Steps S401 and S402 in FIG. 4 are the same as steps S301 and S402 in the first embodiment shown in FIG.

Step S401
The internal combustion engine controller 115 detects the rotational speed and the intake air amount of the internal combustion engine 106 by using the rotational speed sensor 107 and the air flow rate sensor 101, and determines the operating state of the internal combustion engine 106 based on the rotational speed and the intake air amount. . The internal combustion engine control device 115 determines whether or not to allow the passage of exhaust gas through the EGR valve 112 to be stopped for diagnosis based on the information on the operating state by the diagnosis determination unit 205. If permitted, the process proceeds to step S402. If not permitted, the process returns to step S401.

Step S402
When it is permitted to stop the flow rate of the EGR valve 112, the diagnosis execution unit 201 of the internal combustion engine control device 115 causes the EGR valve control unit 209 to instruct the EGR valve 112 to be closed before being fully closed. .

Step S403
When it is detected that the EGR valve 112 is closed, the diagnosis execution unit 201 uses the differential pressure detected by the differential pressure sensor 111 to calculate the pressure at the front stage and the pressure at the rear stage of the EGR valve 112. Further, the diagnosis execution unit 201 calculates the pressure upstream (previous stage) of the GPF 114 based on the pressure upstream (previous stage) of the EGR valve 112. If the EGR valve 112 is fully closed, the pressure on the upstream side of the EGR valve 112 and the pressure on the upstream side (front stage) of the GPF 114 coincide. Further, the diagnosis execution unit 201 calculates the pressure downstream (rear stage) of the air cleaner 118 based on the pressure downstream (rear stage) of the EGR valve 112. If the EGR valve 112 is fully closed, the pressure at the rear stage of the EGR valve 112 matches the pressure at the downstream (rear stage) of the air cleaner 118. The upstream of the GPF 114 is a portion where gas flows into the GPF 114. The downstream of the GPF 114 is a portion where gas flows out of the GPF 114. In the present embodiment, the pressure on the upstream side of the GPF 114 is used in the subsequent processing.

Step S404
The diagnosis determination unit 205 determines whether or not the pressure upstream of the GPF 114 calculated in step S403 is equal to or greater than a preset threshold value. The diagnosis determination unit 205 proceeds to step S405 when the pressure upstream of the GPF 114 is equal to or higher than the threshold value, and stops the diagnosis when the pressure is not equal to or higher than the threshold value. Here, it is determined whether or not the GPF 114 is clogged. If there is clogging of the GPF 114, the process proceeds to step S405 to deal with clogging of the GPF 114. If there is no clogging in the GPF 114, no processing is required, and the process is terminated. The clogging of the GPF 114 can be easily detected by comparing the upstream pressure of the EGR valve 112 (corresponding to the pressure upstream of the GPF 114) with a threshold value.

Step S405
The diagnosis execution unit 201 determines the degree of clogging of the GPF 114 based on the pressure upstream of the GPF 114 calculated in step S403. The diagnosis execution unit 201 determines that the degree of clogging of the GPF 114 is large if the upstream pressure of the GPF 114 is equal to or higher than a preset reference value, and proceeds to step S406. That is, a large degree means that the pressure loss (pressure loss) in the GPF 114 is large. If the upstream pressure of the GPF 114 is smaller than the reference value, it is determined that the degree of clogging of the GPF 114 is small, and the process proceeds to step S407.

Step S406
The process of step S406 is a countermeasure when the degree of clogging of the GPF 114 is large. When it is determined that the degree of clogging of the GPF 114 is large, the filter reproduction unit 210 performs reproduction of the GPF 114. The diagnosis execution unit 201 determines the degree of clogging of the GPF 114 based on the upstream pressure of the GPF 114 (or the upstream pressure of the EGR valve 112), and the filter regeneration unit 210 of the actuator control unit 208 determines whether the GPF 114 is clogged. Accordingly, the regeneration time for purging the clogged GPF 114 may be changed. If there is a lot of clogging, the regeneration time may be lengthened, and if there is little clogging, the regeneration time may be shortened. Filter regeneration can be carried out for an appropriate time according to the degree of clogging of the GPF 114.

Step S407
The process of step S407 is a countermeasure when the degree of clogging of the GPF 114 is small. When it is determined that the degree of the GPF 114 is small, the diagnosis execution unit 201 ends the diagnosis, returns the EGR valve 112 to the normal control by the EGR valve control unit 209, and sends the EGR valve control unit 209 to the EGR valve 112. The opening is controlled in the valve closing direction. The control in the valve closing direction is to reduce the target opening degree in the opening degree control of the EGR valve 112 by a predetermined amount compared to when the GPF 114 is not clogged. For example, the degree of opening may be set according to the degree of clogging of the GPF 114. Since the EGR valve 112 is controlled in the valve closing direction in accordance with the clogging of the GPF 114, it is possible to control the exhaust gas to be recirculated.

  As described above, the internal combustion engine control device 115 according to the second embodiment detects clogging of the GPF 114 using the differential pressure sensor 111 attached so as to straddle the front and back of the EGR valve 112, and further The degree can be diagnosed. Thereby, it is not necessary to provide a differential pressure sensor across the GPF 114 for diagnosis of the GPF 114, and the utility of the control of the EGR valve 112 can be enhanced while reducing the cost. In addition, since the differential pressure sensor straddling the GPF 114 directly detects high-temperature exhaust pressure, high heat resistance is required, but according to the configuration of the second embodiment, the differential pressure sensor 111 was cooled by the intercooler 110. Since the differential pressure of the exhaust is measured, the heat resistance requirement is relatively low.

  In addition, the diagnosis execution unit 201 according to the second embodiment selects and uses an appropriate one from the two coping methods of regeneration of the GPF 114 and control of the valve closing direction of the EGR valve 112 according to the degree of the GPF 114 being clogged. Can do. Thereby, the frequency | count of implementing reproduction | regeneration of GPF114 can be reduced. As a result, the usable period (life) of the GPF 114 can be extended.

  Further, the filter regeneration unit 210 according to the second embodiment can change the regeneration time of the GPF 114 based on the degree of the GPF 114 that is blocked. Thereby, the utility of control of GPF114 can be improved, reducing a fuel consumption.

<Embodiment 3>
The internal combustion engine control apparatus 115 according to the third embodiment can diagnose clogging of the air cleaner 118 in addition to the functions provided in the second embodiment. The internal combustion engine 106 of the third embodiment has the same configuration as that shown in FIG. 1, and the internal combustion engine control device 115 of the third embodiment has the same configuration as that shown in FIG.

  FIG. 5 is a flowchart showing the operation of the internal combustion engine control apparatus 115 according to the third embodiment. Steps S501 to S503 in FIG. 5 are the same as steps S401 to S403 shown in FIG. Steps S504 to S507 are processes unique to the third embodiment.

Step S503
In step S503, as in step S403, the diagnosis execution unit 201 calculates the pressure on the upstream side (front stage) of the GPF 114 and the pressure on the downstream side (back stage) of the air cleaner 118. In the second embodiment, the pressure on the upstream side of the GPF 114 is used, but in this embodiment, the pressure on the downstream side (rear stage) of the air cleaner 118 is used in the subsequent processing.

Step S504
The diagnosis determination unit 205 determines whether or not the pressure downstream of the air cleaner 118 calculated in step S503 is equal to or less than a preset threshold value. The diagnosis determination unit 205 proceeds to step S505 when the pressure downstream of the air cleaner 118 is equal to or lower than the threshold value, and stops the diagnosis when not lower than the set value. Here, it is determined whether or not the air cleaner 118 is clogged. If the air cleaner 118 is clogged, the process proceeds to step S505 to deal with clogging of the air cleaner 118. If there is no clogging of the air cleaner 118, no processing is required and the process is terminated. The clogging of the air cleaner 118 can be easily detected by comparing the downstream pressure of the EGR valve 112 (corresponding to the pressure downstream of the air cleaner 118) with a threshold value.
Step S505
The diagnosis execution unit 201 determines the degree of blockage of the air cleaner 118 based on the pressure downstream of the air cleaner 118 calculated in step S503. If the downstream pressure of the air cleaner 118 is equal to or less than a preset reference value, the diagnosis execution unit 201 determines that the degree of clogging of the air cleaner 118 is large, and proceeds to step S506. That is, a large degree means that the pressure loss (pressure loss) in the air cleaner 118 is large. If the downstream pressure of the air cleaner 118 is greater than the reference value, it is determined that the degree of clogging of the air cleaner 118 is small, and the process proceeds to step S507.

Step S506
The process of step S506 is a countermeasure when the degree of clogging of the air cleaner 118 is large. When it is determined that the air cleaner 118 is clogged, the diagnosis notification unit 207 presents a message prompting the user to replace the air cleaner 118 via the notification unit 211 to the driver. The notification unit 211 presents the message to the driver visually or audibly or both. Visual presentation methods include lighting a warning lamp or displaying on a display screen. As an auditory presentation method, there is a warning sound output or a sound output.

Step S507
The process of step S507 is a countermeasure when the degree of clogging of the air cleaner 118 is small. When it is determined that the degree of clogging of the air cleaner 118 is small, the diagnosis execution unit 201 ends the diagnosis, returns the EGR valve 112 to normal control by the EGR valve control unit 209, and sends the EGR valve control unit 209 to the EGR valve 112. Is controlled in the valve closing direction. Since the EGR valve 112 is controlled in the valve closing direction in accordance with the clogging of the air cleaner 118, it is possible to control so as to maintain the ratio (EGR rate) between fresh air that has passed through the air cleaner 118 and recirculated exhaust gas.

  As described above, the internal combustion engine control apparatus 115 according to the third embodiment detects the clogging of the air cleaner 118 using the differential pressure sensor 111 attached so as to straddle the front and rear of the EGR valve 112, and further The degree can be diagnosed. Thereby, it is not necessary to provide a differential pressure sensor across the air cleaner 118 for diagnosis of the air cleaner 118, and the utility of control of the EGR valve 112 can be enhanced while reducing costs.

Further, the diagnosis execution unit 201 according to the third embodiment selects an appropriate one from the two coping methods, that is, replacement of the air cleaner 118 and control of the valve closing direction of the EGR valve 112 according to the degree of clogging of the air cleaner 118. Can be used. Thereby, the frequency | count of replacing | exchanging the air cleaner 118 can be reduced. As a result, the cost can be further reduced.
<Embodiment 4>
The internal combustion engine control device 115 according to the sixth embodiment can diagnose clogging of the intercooler in addition to the functions provided in the second embodiment. The internal combustion engine 106 of the fourth embodiment has the same configuration as that shown in FIG.

  FIG. 6 is a block diagram of the internal combustion engine control apparatus 115 according to the fourth embodiment. The internal combustion engine control device 115 of the fourth embodiment is different from that of the first embodiment shown in FIG. 1 in that the actuator control unit 208 includes an intercooler temperature raising unit 214.

  FIG. 7 is a flowchart showing the operation of the internal combustion engine control apparatus 115 according to the fourth embodiment. Steps S601 and S602 in the fourth embodiment are the same as steps S401 and S402 in the first embodiment shown in FIG.

Step S603
When it is detected that the EGR valve 112 is closed, the diagnosis execution unit 201 uses the differential pressure sensor 111 to calculate a difference (differential pressure) between the pressure at the front stage and the pressure at the rear stage of the EGR valve 112. Further, the diagnosis execution unit 201 calculates the upstream pressure of the GPF 114 and the downstream pressure of the air cleaner 118 based on the differential pressure. The storage device 213 records the pressure upstream of the GPF 114 and the pressure downstream of the air cleaner 118.

Step S604
The internal combustion engine control device 115 causes the diagnosis determination unit 205 to open the EGR valve 112 and control the intake throttle valve 103 so that the air flow rate detected by the air flow rate sensor 101 is constant.

Step S605
The diagnosis determination unit 205 determines whether or not the air flow rate detected by the air flow rate sensor 101 is constant. The diagnosis determining unit 205 proceeds to step S606 if the air flow rate is constant, and therefore proceeds to step S606. If not, the diagnosis determining unit 205 returns to step S604 because the intercooler 110 cannot be diagnosed. .

  When the diagnosis determining unit 205 determines to execute the diagnosis, the diagnosis executing unit 201 causes the EGR valve control unit 209 to close the EGR valve 112 and determines the state of the internal combustion engine 106 based on the differential pressure detected by the differential pressure sensor 111. Will be judged. Since the EGR valve 112 is closed when the diagnosis is determined, the EGR valve 112 can be closed in the diagnosis and the state of the internal combustion engine 106 can be acquired by the differential pressure sensor 111.

Step S606
The diagnosis execution unit 201 measures the upstream pressure of the EGR valve 112, that is, the downstream pressure of the intercooler 110, using the differential pressure sensor 111 while the air flow rate detected by the air flow rate sensor 101 is constant. Furthermore, the diagnosis execution unit 201 calculates the pressure loss of the intercooler 110 by subtracting the pressure upstream of the GPF 114 measured in step S603 from the downstream pressure of the intercooler 110.

Step S607
The diagnosis execution unit 201 determines whether there is a pressure loss of the intercooler 110 calculated in step S606. The diagnosis execution unit 201 proceeds to step S608 when the pressure loss is not zero, that is, when there is a pressure loss, and ends the diagnosis when the pressure loss is zero, that is, when there is no pressure loss.

  In the processing from step S606 to step S607, the differential pressure across the EGR valve 112 with the EGR valve 112 opened is lower than the differential pressure across the EGR valve 112 detected with the EGR valve 112 closed. In this case, it is possible to determine that pressure loss has occurred due to clogging of the intercooler 110. The clogging of the intercooler 110 can be easily determined based on whether or not the differential pressure between the EGR valve 112 in the opened state and the closed EGR valve 112 is equal.

Step S608
The diagnosis execution unit 201 determines the degree of blocking of the intercooler 110 based on the pressure loss of the intercooler 110 calculated in step S606. If the pressure loss of the intercooler 110 is equal to or greater than a preset reference value, the diagnosis execution unit 201 determines that the degree of clogging of the intercooler 110 is large, and proceeds to step S609. On the other hand, if the pressure loss of the intercooler 110 is smaller than the reference value, the diagnosis execution unit 201 determines that the degree of clogging of the intercooler 110 is small, and proceeds to step S610.

Step S609
When it is determined that the degree of clogging of the intercooler 110 is large, the intercooler temperature raising unit 214 heats the circulating water of the intercooler 110 to raise the temperature, thereby reducing the cooling capacity of the intercooler 110. Thereby, it is possible to suppress the exhaust gas from being excessively cooled by the clogging of the intercooler 110.

Step S610
When it is determined that the degree of clogging of the intercooler 110 is small, the diagnosis execution unit 201 returns the EGR valve 112 to normal control by the EGR valve control unit 209, and the EGR valve control unit 209 opens the EGR valve 112. Control in the direction. The control in the valve opening direction is to increase the target opening in the opening control of the EGR valve 112 by a predetermined amount compared to when the intercooler 110 is not clogged. For example, the degree of opening may be set according to the degree of clogging of the intercooler 110. When the intercooler 110 is clogged, the EGR valve 112 is controlled in the valve opening direction accordingly. Therefore, the reduction of the recirculated exhaust gas due to the blockage of the intercooler 110 is suppressed, and the recirculated exhaust gas amount is controlled. be able to.

  As described above, according to the fourth embodiment, the internal combustion engine control device 115 detects the clogging of the intercooler 110 using the differential pressure sensor 111 provided across the front and rear of the EGR valve 112, and further the intercooler 110. The degree of clogging can be diagnosed. Thereby, it is not necessary to provide a differential pressure sensor across the intercooler 110 for diagnosis of the intercooler 110, and the utility of the control of the EGR valve 112 can be enhanced while reducing costs.

  In the fourth embodiment, the diagnosis execution unit 201 selects an appropriate one from the two coping methods, that is, the temperature rise of the intercooler 110 and the control of the valve opening direction of the EGR valve 112, according to the degree of clogging of the intercooler 110. Can be used. Thereby, the frequency | count of replacing | exchanging the air cleaner 118 can be reduced. As a result, the cost can be further reduced.

When the differential pressure sensor is installed so as to straddle the intercooler 110 as in the prior art, the pressure difference detected by the differential pressure sensor increases regardless of which of the GPF 114 and the intercooler 110 is clogged. Therefore, when the pressure difference detected by the differential pressure sensor has increased, it has not been possible to determine which is clogged. Further, when both of them are clogged at the same time, it is difficult to detect the clogging because the clogging with the smaller clogging is hidden by the influence of the clogging with the larger clogging. That is, when both the GPF 114 and the intercooler 110 are clogged, it is difficult to detect the clogging of a device with a small degree. On the other hand, according to the internal combustion engine control apparatus 115 according to the fourth embodiment, the blockage of the intercooler 110 and the blockage of the GPF 114 can be detected separately and independently.
<Embodiment 5>
The fifth embodiment is an example in which diagnosis is performed when the travel distance becomes a certain distance or more. The object of diagnosis is the same as in the first to fourth embodiments, and is, for example, a GPF, an air cleaner, or an intercooler. The internal combustion engine 106 of the fifth embodiment has the same configuration as that shown in FIG. 1, and the internal combustion engine control device 115 of the fifth embodiment has the same configuration as that shown in FIG.

  FIG. 8 is a flowchart showing the operation of the internal combustion engine control apparatus 115 according to the fifth embodiment. In the fifth embodiment, it is determined in step S701 to step S703 shown in FIG. When performing diagnosis, the EGR valve 112 is closed in step S703.

  The processing after closing the EGR valve 112 is the same as that in the first to fourth embodiments. If it is Embodiment 1, the process of step S303-step S304 shown in FIG. 3 will be performed. If it is Embodiment 2, the process of step S403-step S407 shown in FIG. 4 will be performed. If it is Embodiment 3, the process of step S503-step S507 shown in FIG. 5 will be performed. If it is Embodiment 4, the process of step S603-step S610 shown in FIG. 7 will be performed.

Step S701
The diagnosis determination unit 205 acquires information on the accumulated travel distance measured by the odometer of the vehicle on which the internal combustion engine 106 is mounted, and determines whether the accumulated travel distance is equal to or greater than a preset diagnosis execution reference distance. If the accumulated travel distance is equal to or greater than the diagnosis execution reference distance, diagnosis determination unit 205 determines to execute diagnosis of GPF 114, air cleaner 118, and intercooler 110, and the process proceeds to step S703. If the accumulated travel distance does not satisfy the diagnosis execution reference distance, the diagnosis determination unit 205 proceeds to step S702.

Step S702
FIG. 9 is a diagram showing the relationship between the flow rate of exhaust gas passing through the EGR valve 112 and the flow rate of fresh air drawn through the air cleaner 118. The flow rate of fresh air drawn through the air cleaner 118 is detected by the air flow rate sensor 101.

  When the GPF 114 or the air cleaner 118 is clogged, the ratio of the flow rate of the exhaust gas passing through the EGR valve 112 to the flow rate of fresh air sucked through the air cleaner 118 increases as compared with the normal time. In other words, the ratio of the flow rate of the exhaust gas passing through the EGR valve 112 to the flow rate of fresh air sucked through the air cleaner 118 is reduced as compared with the normal time when the intercooler 110 is used. The influence of the flow rate error of the exhaust gas passing through the EGR valve 112 depends on the flow rate of fresh air sucked through the air cleaner 118. If the flow rate of fresh air sucked from the outside through the air cleaner 118 increases, the influence of the flow rate error of the EGR valve 112 is reduced and the accuracy of diagnosis is increased.

  Therefore, in step S702, the diagnosis determining unit 205 determines whether to close the EGR valve 112, that is, whether to permit the diagnosis, based on the air flow rate detected by the air flow rate sensor 101. If the air flow rate detected by the air flow rate sensor 101 is equal to or higher than a preset diagnosis execution reference flow rate, the diagnosis determination unit 205 determines to execute the diagnosis of the GPF 114, the air cleaner 118, or the intercooler 110, and the step The process proceeds to S703. If the air flow rate detected by the air flow rate sensor 101 does not satisfy the diagnosis execution reference flow rate, the diagnosis determination unit 205 ends the diagnosis.

  Note that if the air flow rate detected by the air flow rate sensor 101 increases, the EGR rate decreases, so that knocking of the internal combustion engine 106 is likely to occur. In this embodiment, when the EGR valve 112 is closed and the diagnosis is executed because the air flow rate detected by the air flow rate sensor 101 has increased, the internal combustion engine control device 115 is retarded from the ignition timing during normal operation. The ignition timing may be used. By retarding the ignition timing, knocking of the internal combustion engine 106 can be suppressed.

  As described above, the internal combustion engine control apparatus 115 according to the fifth embodiment executes the clogging diagnosis of the GPF 114, the air cleaner 118, or the intercooler 110 when the accumulated traveling distance reaches a predetermined distance. Thereby, the normal performance of the internal combustion engine 106 can be ensured.

  Further, the internal combustion engine control device 115 according to the fifth embodiment performs diagnosis when the flow rate of air newly sucked from the outside through the air cleaner 118 exceeds a predetermined amount. The diagnosis accuracy can be improved by executing the diagnosis when the air flow rate from the outside is large.

  Further, the internal combustion engine control apparatus 115 according to the fifth embodiment can suppress knocking of the internal combustion engine 106 by retarding the ignition timing when the diagnosis is performed in a state where the flow rate of air sucked from the outside is large.

<Modification>
The embodiment described above can be variously modified within the scope of the present invention. For example, the above-described embodiments use specific examples in order to explain the present invention in an easy-to-understand manner. However, it is not necessarily limited to having all the configurations described. A part of the configuration of an embodiment can be replaced with the configuration of another example, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  The internal combustion engine control apparatus 115 according to the second embodiment diagnoses whether or not the GPF 114 is clogged using the differential pressure sensor 111 provided so as to straddle the front and rear of the EGR valve 112. However, as a modification of the second embodiment, a second differential pressure sensor may be provided so as to straddle the front and rear of the GPF 114. The second differential pressure sensor measures the difference (differential pressure) between the upstream (front) and downstream (rear) pressure of the GPF 114, and the presence or absence of the GPF 114 can be determined from the differential pressure. Therefore, in a modification, the diagnosis execution unit 201 uses the detection value of the first differential pressure sensor 111 provided in the EGR valve 112 and the detection value of the second differential pressure sensor, and uses the first differential pressure sensor. The normality of 111 and the second differential pressure sensor can be examined. If the degree of clogging based on the detection value of the first differential pressure sensor 111 and the degree of clogging based on the detection value of the second differential pressure sensor are within a certain range, the first differential pressure sensor 111 and the second differential pressure sensor 111 It can be determined that the differential pressure sensor is normal. If the degree of clogging based on the detection value of the first differential pressure sensor 111 and the degree of clogging based on the detection value of the second differential pressure sensor are outside a certain range, the first differential pressure sensor 111 and the second differential pressure sensor 111 It can be estimated that at least one of the differential pressure sensors is abnormal.

  Moreover, although the internal combustion engine 106 of the above-described embodiment is assumed to be a spark ignition internal combustion engine including the ignition plug 105, a compression ignition internal combustion engine (for example, a diesel engine or a premixed compression ignition engine is used). Thing).

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

DESCRIPTION OF SYMBOLS 101 ... Air flow sensor, 102 ... Cylinder, 103 ... Intake throttle valve, 104 ... Intake chamber, 106 ... Internal combustion engine, 107 ... Revolution sensor, 108 ... Turbocharger, 109 ... Pre-catalyst, 110 ... Intercooler, 111 ... Differential pressure Sensor 112, EGR valve 113, main catalyst 114, GPF 115, internal combustion engine controller 116 116 intake pipe 117 117 variable phase valve timing mechanism 118 air cleaner 119 exhaust path 120 EGR pipe DESCRIPTION OF SYMBOLS 201 ... Diagnosis execution part, 202 ... Detection part, 203 ... Travel distance detection part, 204 ... Sensor, 205 ... Diagnosis determination part, 207 ... Diagnosis notification part, 208 ... Actuator control part, 209 ... EGR valve control part, 210 ... Filter Reproduction unit 211 ... notification unit 213 ... storage device 214 ... intercool Temperature-raising section

Claims (15)

An internal combustion engine control device for controlling an internal combustion engine configured to separate a part of exhaust from a cylinder, cool with a cooler, mix with intake air via an exhaust recirculation valve, and supply the intake to the cylinder,
A first differential pressure sensor that is installed across the exhaust recirculation valve and detects a difference between the pressure at the front stage and the pressure at the rear stage of the exhaust recirculation valve as a recirculation valve differential pressure;
A control unit for controlling the exhaust gas recirculation valve;
A diagnosis execution unit for causing the control unit to close the exhaust recirculation valve and determining the state of the internal combustion engine based on the recirculation valve differential pressure detected by the first differential pressure sensor in the state;
An internal combustion engine control device. There is a filter in the exhaust path from the cylinder, the exhaust to the exhaust recirculation valve is separated upstream of the filter,
The diagnosis execution unit calculates a pressure upstream of the exhaust recirculation valve as a recirculation valve upstream pressure based on the recirculation valve differential pressure, and if the recirculation valve upstream pressure is equal to or higher than a predetermined threshold, Judge that the filter is clogged,
The internal combustion engine control device according to claim 1. There is an air cleaner that purifies air in the intake path to the cylinder, the downstream side of the exhaust gas recirculation valve joins the downstream side of the air cleaner,
The diagnosis execution unit calculates a downstream pressure of the exhaust gas recirculation valve as a recirculation valve downstream pressure based on the recirculation valve differential pressure, and the recirculation valve downstream pressure is equal to or lower than a predetermined threshold value, Judging that the air cleaner is clogged,
The internal combustion engine control device according to claim 1. The diagnosis execution unit causes the control unit to open the exhaust gas recirculation valve and controls the flow rate of the intake air to the cylinder, thereby closing the exhaust gas recirculation valve to the flow rate of the exhaust gas passing through the filter. The recirculation valve differential pressure detected by the first differential pressure sensor in that state is lower than the recirculation valve differential pressure detected with the exhaust recirculation valve closed. If so, determine that the cooler is clogged,
The internal combustion engine control device according to claim 2. A diagnostic determination unit that determines execution of the diagnosis of the internal combustion engine;
When the diagnosis is determined by the diagnosis determination unit, the diagnosis execution unit causes the control unit to close the exhaust recirculation valve and detect the recirculation valve detected by the first differential pressure sensor. Determining the state of the internal combustion engine based on the differential pressure;
The internal combustion engine control device according to claim 1. The diagnosis execution unit causes the control unit to close the exhaust gas recirculation valve when the air flow rate in the intake passage exceeds a predetermined threshold, and the recirculation valve detected by the first differential pressure sensor in that state. Determining the state of the internal combustion engine based on the differential pressure;
An internal combustion engine control device according to claim 1, When the exhaust gas recirculation valve is closed, the control unit retards the ignition timing from the ignition timing during normal operation.
The internal combustion engine control device according to claim 1. A second differential pressure sensor that is installed across the filter and detects a difference between the pressure at the front stage and the pressure at the rear stage of the filter as a filter differential pressure;
The diagnosis execution unit determines normality of the first differential pressure sensor and the second differential pressure sensor based on a value detected by the first differential pressure sensor and a value detected by the second differential pressure sensor. To judge,
The internal combustion engine control device according to claim 2. The control unit further controls filter regeneration for purifying the clogging of the filter,
The diagnosis execution unit determines the degree of clogging of the filter based on the recirculation valve upstream pressure,
The control unit changes a regeneration time for purifying the filter clogging according to the degree of clogging of the filter.
The internal combustion engine control device according to claim 2. When the diagnosis execution unit determines that the filter is clogged, the control unit causes the control unit to control the exhaust gas recirculation valve in a valve closing direction.
The internal combustion engine control device according to claim 2. The control unit further controls filter regeneration for purifying the clogging of the filter,
The diagnosis execution unit determines the degree of clogging of the filter based on the recirculation valve upstream pressure,
If the degree of clogging of the filter is greater than or equal to a predetermined reference value based on the determination by the diagnosis execution unit, the control unit performs filter regeneration to purify the clogging of the filter, and the degree of clogging of the filter If smaller than the reference value, the exhaust gas recirculation valve is controlled in the valve closing direction.
The internal combustion engine control device according to claim 2. When the diagnosis execution unit determines that the air cleaner is clogged, the control unit causes the control unit to control the exhaust gas recirculation valve in a valve closing direction.
The internal combustion engine control device according to claim 3. The diagnosis execution unit determines the degree of clogging of the air cleaner based on the downstream pressure of the recirculation valve,
If the degree of clogging of the air cleaner is greater than or equal to a predetermined reference value based on the determination by the diagnosis execution unit, the control unit prompts replacement of the air cleaner, and if the degree of clogging of the air cleaner is smaller than the reference value Controlling the exhaust gas recirculation valve in the valve closing direction;
The internal combustion engine control device according to claim 3. When the diagnosis execution unit determines that the cooler is clogged, the control unit causes the control unit to control the exhaust gas recirculation valve in a valve opening direction.
The internal combustion engine control device according to claim 4. An internal combustion engine control method for controlling an internal combustion engine configured to separate a part of exhaust gas from a cylinder, cool it with a cooler, mix it with intake air via an exhaust gas recirculation valve, and supply it to the cylinder ,
Close the exhaust recirculation valve;
The first differential pressure sensor installed across the exhaust recirculation valve detects a difference between the pressure at the front stage and the pressure at the rear stage of the exhaust recirculation valve as a recirculation valve differential pressure,
Determining the state of the internal combustion engine based on a recirculation valve differential pressure detected by the first differential pressure sensor;
Internal combustion engine control method.

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