JP6569384B2 - Internal combustion engine system - Google Patents

Description

  The present invention relates to an engine system including a supercharger and an exhaust gas recirculation device.

  The gasoline engine is becoming a mainstream so-called downsizing turbo engine, in which both the fuel consumption performance and the output performance are achieved by compensating for the output reduction accompanying the reduction in the exhaust amount with a supercharger while reducing the exhaust amount. In addition, an exhaust gas recirculation device that improves fuel efficiency performance by recirculating a part of exhaust gas (hereinafter also referred to as EGR gas) to the intake passage to reduce pumping loss and improve knocking resistance. Hereinafter, it is also known as an EGR device).

  In recent years, demands for improving fuel efficiency have increased, and in order to meet these demands, it is necessary to realize a higher EGR rate in a wider driving range. Since the EGR device recirculates the EGR gas using the differential pressure between the exhaust passage and the intake passage, for example, in order to recirculate the EGR gas in the supercharging region in a downsizing turbo engine, a position where the EGR gas is introduced. Needs to be an intake passage that is at almost the atmospheric pressure upstream of the supercharger. That is, the volume from the position where EGR gas is introduced to the engine (intake volume) becomes larger than that of the conventional EGR device that introduces EGR gas downstream of the throttle valve. As a result, when the intake air amount decreases as in deceleration, the EGR gas already in the intake passage is controlled even if the EGR valve that controls the EGR gas amount is controlled to close in accordance with the decrease in the intake air amount. Is introduced into the cylinder, resulting in an excessively high EGR rate, which may lead to deterioration in operability and misfire due to deterioration in combustion stability.

  As a configuration for solving such a problem, Patent Document 1 discloses a fresh air bypass passage that communicates the EGR gas introduction position of the intake passage and the downstream side of the throttle valve, and a fresh air provided in the fresh air bypass passage. A configuration including a bypass valve is disclosed. In this configuration, during deceleration, the throttle valve is controlled in the closing direction and the fresh air bypass valve is controlled in the opening direction.

JP 2012-7547 A

  However, in the configuration of the above document, since the high-pressure EGR gas stays on the throttle valve side of the fresh air bypass valve in the fresh air bypass passage, even if the timing for closing the throttle valve is just after detecting the deceleration request, If the bypass valve is opened, the EGR gas flows backward in the fresh air bypass passage. This hinders the introduction of fresh air into the engine and may deteriorate the combustion stability. That is, the configuration described in the above document cannot solve the problem that the combustion stability deteriorates during deceleration.

  Note that the lower the set value of the EGR rate, the smaller the influence of the EGR gas staying in the intake passage, so that the above-mentioned problem is less likely to occur, but it is difficult to satisfy the demand for improvement in fuel efficiency.

  Therefore, an object of the present invention is to further enhance the effect of improving the fuel efficiency by the EGR device by suppressing the deterioration of the combustion stability described above.

According to an aspect of the present invention, a turbocharger, a first intake passage where a turbocharger compressor is disposed, a first exhaust passage where a turbocharger turbine is disposed, and a first intake air There is provided an internal combustion engine system comprising a throttle chamber disposed downstream of a compressor in a passage. The internal combustion engine system further includes an exhaust gas recirculation passage that communicates the downstream side of the turbine of the first exhaust passage and the upstream side of the compressor of the first intake passage, and an exhaust gas recirculation that adjusts an exhaust gas flow rate that passes through the exhaust gas recirculation passage. A circulation amount control valve. Further, the internal combustion engine system is disposed in a second intake passage and a second intake passage that communicates the downstream side of the throttle chamber of the first intake passage and the upstream side of the junction of the exhaust gas recirculation passage of the first intake passage. The internal pressure of the first intake passage which is disposed downstream of the first intake throttle valve and the first intake throttle valve of the second intake passage and which is downstream of the throttle chamber is lower than the internal pressure of the second intake passage. And a valve that opens in the event of a failure. The internal combustion engine system then opens the throttle chamber so that the minimum amount of air can be obtained within a range that does not misfire when the required exhaust gas recirculation rate decreases by a predetermined amount or more and the valve is closed. When the amount of decrease in the required exhaust gas recirculation rate is equal to or greater than a predetermined amount and the valve is open, the throttle chamber is controlled in the closing direction, and the first intake throttle valve Is provided with a control unit for controlling the opening direction. The internal combustion engine system further has one end of the second intake passage connected to the upstream side of the joining portion of the first intake passage with the exhaust gas recirculation passage, and the joining portion of the first intake passage upstream of the compressor and the second intake passage. A second intake throttle valve is provided further downstream, and the control unit controls the second intake throttle valve in the closing direction when the amount of decrease in the required exhaust gas recirculation rate exceeds a predetermined amount.

  According to the above aspect, the provision of the valve in the second intake passage prevents the EGR gas staying in the first intake passage from flowing back through the second intake passage, so that the first intake passage internal pressure is set to the second intake passage. When the pressure becomes lower than the passage internal pressure, fresh air can be quickly supplied into the cylinder, and deterioration of combustion stability in a state where the amount of decrease in the required exhaust gas recirculation rate is equal to or greater than a predetermined amount as in the deceleration state can be suppressed. As a result, the EGR rate in the running state other than the deceleration state can be set higher, so that the fuel consumption performance can be improved.

FIG. 1 is a schematic configuration diagram of an internal combustion engine system according to the first embodiment. FIG. 2 is a flowchart of a control routine executed by the controller. FIG. 3 is a flowchart of the control routine following step S50 in FIG. FIG. 4 is a flowchart of the control routine following step S40 in FIG. FIG. 5 is a timing chart when the control routine of FIG. 2 is executed. FIG. 6 is a schematic configuration diagram of an internal combustion engine system according to the second embodiment. FIG. 7 is a schematic configuration diagram of an internal combustion engine system according to the third embodiment. FIG. 8 is a schematic configuration diagram of an internal combustion engine system according to the fourth embodiment. FIG. 9 is a schematic configuration diagram of an internal combustion engine system according to the fifth embodiment.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of an internal combustion engine system 100 according to the first embodiment. In the first intake passage 2 of the internal combustion engine 1, in order from the upstream side of the intake flow, a first air flow meter 14, a compressor 5 </ b> A of the turbocharger 5, a throttle chamber (hereinafter also referred to as TH / C) 4, The intercooler 6 is arranged.

  In the first exhaust passage 3 of the internal combustion engine 1, a turbine 5B of the turbocharger 5 and an exhaust purification device 7 such as a three-way catalyst are arranged in this order from the upstream side of the exhaust flow.

  In the present embodiment, the case where the turbocharger 5 is used will be described. However, the present invention is not limited to this. For example, a mechanical supercharger or an electric supercharger may be used. .

  The internal combustion engine system 100 includes an exhaust gas recirculation passage (hereinafter also referred to as an EGR passage) 8 that communicates the downstream side of the first exhaust passage 3 with respect to the exhaust purification device 7 and the upstream side of the compressor 5A of the first intake passage 2. Prepare. An EGR cooler 9 that cools the exhaust gas flowing through the EGR passage 8 and an EGR valve (hereinafter also referred to as EGR / V) 10 that controls the flow rate of the exhaust gas flowing through the EGR passage 8 are disposed in the EGR passage 8. . The EGR device includes the EGR passage 8, the EGR cooler 9, and the EGR / V10.

  The internal combustion engine system 100 also includes a second intake passage 11 that communicates the downstream side of the first intake passage 2 with respect to TH / C4 and the upstream side of the junction with the EGR passage 8 of the first intake passage 2. A first admission valve (hereinafter also referred to as ADM / V) 12 as a first intake throttle valve is disposed in the second intake passage 11.

  At the junction of the first intake passage 2 and the second intake passage 11 on the downstream side of TH / C4, the check valve 13 opens when the internal pressure of the second intake passage 11 becomes higher than the internal pressure of the first intake passage. Is arranged. The backflow prevention valve 13 of this embodiment is a so-called poppet type valve in which the valve body moves in a direction perpendicular to the valve seat surface. The valve body is not limited to the poppet type valve, but may be a so-called swing type or wafer type that has a configuration in which the valve body is pressed against the valve seat when the valve is closed. Further, the backflow prevention valve 13 may be interposed in the second intake passage 11.

  The first air flow meter 14 detects the amount of air flowing into the first intake passage 2. The detected air amount is read into the controller 20 as a control unit. In the present embodiment, the first air flow meter 14 is used. However, the first air flow meter 14 is not limited to this, and any device that can detect or estimate the intake air amount may be used. For example, it can be estimated based on the pressure in the first intake passage 2 downstream of TH / C4 and the opening degree of TH / C4.

  In addition to the detection value of the first air flow meter 14, the controller 20 reads detection values of a crank angle sensor, an accelerator opening sensor, etc. (not shown). Then, the controller 20 performs opening control of TH / C4 and EGR / V10, fuel injection control, ignition timing control, and the like based on these detected values. The controller 20 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). It is also possible to configure the controller 20 with a plurality of microcomputers.

  The EGR device of this embodiment is a so-called low pressure / EGR device (hereinafter also referred to as an LP-EGR device) in which the EGR passage 8 is connected to the upstream side of the compressor 5A. The EGR rate is the ratio of EGR gas to the total gas flowing into the internal combustion engine 1. Control for recirculating EGR gas is referred to as EGR control.

  It is known that when the EGR gas is recirculated, the opening degree of TH / C4 is increased by the amount of EGR gas introduced, so that the pumping loss is reduced and the fuel efficiency is improved. It is also known that when the EGR gas is recirculated, the combustion temperature is lowered and the knocking resistance is improved, so that the ignition timing retardation amount for avoiding knocking is reduced and the fuel efficiency is improved. Therefore, in order to improve fuel consumption performance, it is desirable to execute EGR control in a wider driving range. In this respect, the LP-EGR device recirculates EGR gas upstream of the compressor 5A, so that EGR control can be performed even in the supercharging region, and fuel efficiency performance of the internal combustion engine with a supercharger can be improved. It can be said that it is a device suitable for.

  By the way, in the LP-EGR device, since the EGR passage 8 is connected to the upstream side of the compressor 5A, the path length from the connection portion with the EGR passage 8 to the cylinder tends to be long. During execution of EGR control, EGR gas is present from the junction of the first intake passage 2 with the EGR passage 8 to the inside of the cylinder. For this reason, even after the EGR / V10 is closed, the EGR gas existing in the first intake passage 2 continues to flow into the cylinder. Even when TH / C4 is closed, EGR gas existing in the intake path from TH / C4 to the cylinder continues to flow into the cylinder.

  For example, when a vehicle deceleration request is issued and the internal combustion engine 1 enters a deceleration state, the required intake air amount decreases and the target EGR rate also decreases, so that the required EGR gas amount also decreases. At this time, by simply controlling TH / C4 and EGR / V10 in the closing direction, the EGR gas introduced according to the target EGR rate before the deceleration state for a while flows into the cylinder, The actual EGR rate becomes higher than the target EGR rate in the deceleration state. As a result, the combustion stability deteriorates and there is a risk of misfire.

  Therefore, in the present embodiment, the first ADM / V12, TH / C4, and EGR / V10 are controlled as described below in order to ensure combustion stability even in the deceleration state. The control described below may be executed only in a deceleration state in which the target EGR rate changes to such an extent that a misfire may occur if the TH / C4 and the EGR / V10 are simply controlled in the closing direction. .

  FIG. 2 is a flowchart of a control routine executed by the controller 20.

  In step S10, the controller 20 determines whether or not there is a vehicle deceleration request. If there is a vehicle deceleration request, the process of step S20 is executed. If there is no vehicle deceleration request, the process of step S130 is executed.

  In step S130, the controller 20 executes an air amount control and an EGR control at the time of acceleration, constant speed, or engine stop. These controls are known control contents. For example, the required air amount and the EGR rate are set by map search or the like according to the operation state, and TH / C4 and EGR / V10 are opened and closed to become the set values. Control.

  In step S20, the controller 20 calculates the external EGR rate in the deceleration state (external EGR rate at the time of deceleration request). The external EGR rate at the time of the deceleration request is calculated by creating a map in which the EGR rate is assigned to the engine rotation speed and the engine load in advance and storing the map in the controller 20 and retrieving it. The external EGR gas is the ratio of EGR gas introduced through the EGR passage 8 to the total gas flowing into the cylinder. On the other hand, the ratio of burnt gas (internal EGR gas) remaining in the cylinder without being discharged in the exhaust stroke of the internal combustion engine 1 with respect to the total gas amount is referred to as an internal EGR rate.

  In step S30, the controller 20 controls the opening / closing of the EGR / V10 according to the external EGR rate at the time of a deceleration request. The opening degree of the EGR / V10 is set by mapping the relationship between the external EGR rate at the time of deceleration request and the opening degree of the EGR / V10 in advance and storing it in the controller 20 and searching for it.

  In step S40, the controller 20 determines whether or not the total EGR rate is greater than the misfire limit EGR rate. The total EGR rate is a ratio of the total EGR gas amount obtained by adding the external EGR gas and the internal EGR gas to the total gas amount flowing into the cylinder.

  In the deceleration state, the opening of TH / C4 becomes small, so it is difficult for the inside of the cylinder to be scavenged, and the internal EGR rate tends to increase. Therefore, the controller 20 estimates the internal EGR rate in the deceleration state based on the EGR rate before entering the engine operating state or the deceleration state. As an estimation method, a map created in advance may be searched, or a calculation formula created in advance may be used.

  The misfire limit EGR rate is the maximum EGR rate at which misfire does not occur, and is set in advance by experiments or the like for each internal combustion engine to which the present embodiment is applied.

The controller 20 executes the process of step S50 when the total EGR rate is larger than the misfire limit EGR rate, and executes the process of step S200 of FIG. 4 when it is equal to or less than the misfire limit EGR rate.

In step S50, the controller 20 determines whether the pressure in the first intake passage 2 is lower than the pressure in the second intake passage 11, and if the pressure in the first intake passage 2 is lower, step S60. If not, the process of step S160 in FIG. 3 is executed. A pressure sensor may be provided in each of the first intake passage 2 and the second intake passage 11 to compare the detected pressures. Here, the determination is made based on whether or not the backflow prevention valve 13 is open. This is because the backflow prevention valve 13 is set to open when the pressure in the first intake passage 2 becomes lower than the pressure in the second intake passage 11 as described above.

  In step S60, the controller 20 determines the amount of air that passes TH / C4 (TH / C passage required air) so that the total air amount introduced into the internal combustion engine 1 becomes the required air amount in the deceleration state and no misfire occurs. Amount) and the amount of air passing through the first ADM / V12 (ADM / V passage required air amount). The required air amount in the deceleration state (deceleration required air amount) will be described later.

  As determined in step S40, misfire occurs at the current total EGR rate. Therefore, fresh air introduced via the second intake passage 11 is introduced via TH / C4 in order to prevent misfire. It is necessary to dilute the EGR gas to reduce the total EGR rate. Therefore, the controller 20 sets the TH / C passage request air amount and the ADM / V passage request air amount based on the current total EGR rate and the misfire limit EGR rate. After calculating these, the controller 20 executes steps S70 to S90 and steps S100 to S120 described below in parallel.

  In step S70, the controller 20 controls opening / closing of the first ADM / V12 according to the ADM / V passage required air amount.

  In step S80, the controller 20 acquires the amount of air passing through the second intake passage 11 (second intake passage air amount). Specifically, the controller 20 performs the second operation based on the amount of air detected by the first air flow meter 14 and the ratio of the amount of air passing through the first intake passage 2 and the amount of air passing through the second intake passage 11. The amount of air in the intake passage is calculated. Since the ratio is determined according to the opening degree of TH / C4 and the opening degree of the first ADM / V12, the relationship between the opening ratio of TH / C4 and the opening degree of the first ADM / V12 and the ratio is preliminarily investigated and mapped. The controller 20 searches for this.

  In step S90, the controller 20 determines whether or not the ADM / V passage required air amount is equal to the second intake passage air amount, and repeats steps S70 to S90 until they become equal.

  In step S100, the controller 20 controls the opening / closing of TH / C4 according to the TH / C passage required air amount.

  In step S110, the controller 20 acquires the amount of air passing through the first intake passage 2 (first intake passage air amount). The controller 20 acquires the amount of air in the first intake passage as in step S80.

  In Step S120, the controller 20 determines whether or not the TH / C passage required air amount is equal to the first intake passage air amount, and repeats Steps S100 to S120 until they become equal.

  When the processing of step S90 and step S120 is completed, the controller 100 determines whether or not the deceleration request has been lost in step S130. If not, the first ADM / V12 is fully opened in step S140 and the current routine is ended. To do. If there is a deceleration request, the current routine is terminated.

  The processing in steps S60 to S120 is performed after it is determined in step S50 that the pressure in the first intake passage 2 is lower than the pressure in the second intake passage 11, that is, the air does not flow backward through the second intake passage 11. It is done after becoming a state. Thereby, air can be promptly supplied into the cylinder while diluting the EGR gas remaining in the first intake passage 2 without the EGR gas flowing back through the second intake passage 11.

  On the other hand, in step S <b> 160 of FIG. 3 executed when it is determined in step S <b> 50 that the pressure in the first intake passage 2 is equal to or higher than the pressure in the second intake passage 11, the controller 20 sets the minimum required air amount. The minimum required air amount here is the smallest air amount within a range where no misfire occurs. Combustion becomes unstable as the amount of air decreases. In other words, the misfire limit EGR rate increases as the amount of air increases. Therefore, the minimum required air amount is set to an air amount that does not exceed the misfire limit EGR rate even with the current total EGR rate.

  In step S170, the controller 20 controls the opening / closing of TH / C4 according to the minimum required air amount.

  In step S180, the controller 20 acquires the air amount in the first intake passage as in step S110.

  In step S190, the controller 20 determines whether or not the minimum required air amount is the same as the first intake passage air amount, and repeats steps S170 to S190 until it becomes the same, thereby terminating the current routine.

  In many cases, steps S160 to S190 are executed after transition from the acceleration or constant vehicle speed to the deceleration state. Further, by executing the processing of steps S160 to S190, misfire can be prevented even in a state where dilution with fresh air supplied through the second intake passage 11 (steps S60 to S120) cannot be performed.

  Further, in step S200 of FIG. 4 executed when it is determined in step S40 that the total EGR rate is equal to or less than the misfire limit EGR rate, the controller 20 calculates the deceleration required air amount. Here, the deceleration request air amount will be described. The deceleration required air amount is a required air amount of the internal combustion engine 1 in the deceleration state. In the deceleration state in which so-called fuel cut is executed, the required air amount of the internal combustion engine 1 becomes zero. However, a torque shock may occur due to fuel cut depending on the operating state before the deceleration state. Further, if the fuel cut is performed suddenly, air is supplied to the exhaust catalyst due to the inertial rotation of the internal combustion engine 1, so that the NOx emission amount increases when returning from the fuel cut. Therefore, in order to suppress torque shock and NOx emission amount, the internal combustion engine 1 can be operated while gradually reducing the air amount without starting the fuel cut immediately after the deceleration state. is there.

  Further, for example, when the accelerator opening is decreased after merging with the main line on a highway, the internal combustion engine 1 is kept in a decelerating state while operating.

  When the internal combustion engine 1 as described above is decelerated while operating, it is necessary to reduce the engine speed while performing combustion in the internal combustion engine 1. That is, it is necessary to control the output of the internal combustion engine 1 to such a magnitude that the friction cannot be overcome. The required air amount at this time is the deceleration required air amount.

  In step S210, the controller 20 controls the opening / closing of TH / C4 according to the deceleration request air amount.

  In step S220, the controller 20 acquires the first intake passage air amount in the same manner as in step S110.

  In step S230, the controller 20 determines whether or not the deceleration requesting air amount is the same as the first intake passage air amount, and repeats steps S200 to S230 until it becomes the same, thus ending the current routine.

  FIG. 5 is a timing chart when the accelerator opening degree transits from a traveling state where the accelerator opening degree is a medium / high opening degree to a deceleration state where the accelerator opening degree is a low opening degree. A broken line in the chart of the ENG introduction total EGR rate indicates a transition in a case where dilution with fresh air introduced from the second intake passage 11 is not performed (hereinafter referred to as a comparative example).

  In the comparative example, since the EGR gas staying in the intake system flows into the cylinder even after the amount of intake air is reduced in response to the deceleration state, the entire gas introduced into the internal combustion engine 1 is reduced. The EGR rate (ENG introduction Total EGR rate) increases immediately after the deceleration state is reached and exceeds the misfire limit.

  In order to pay attention to the processing of steps S50 to S120, which is a characteristic part of the present embodiment, in the first calculation, the total EGR rate is higher than the misfire limit EGR rate in step S40, and the first intake passage internal pressure is set to the second in step S50. It shows a case where it is determined that the pressure is lower than the intake passage internal pressure. Even in this case, there is a time difference between the transition to the deceleration state and the opening of the backflow prevention valve 13, but in FIG. 5 the backflow prevention valve 13 is opened at timing T1 for simplicity.

  When the state transitions to the deceleration state at timing T1, the required air amount (ENGTotal required air amount) of the internal combustion engine 1 and the target value of the EGR rate (ENG introduction Target EGR rate) decrease. The first ADM / V12 is controlled in the opening direction and TH / C4 is controlled in the closing direction by the processing in steps S60, S70, and S100 in FIG. As a result, the amount of air flowing into the cylinder via the second intake passage 11 (the amount of supply air via the second intake passage) increases, and the amount of air flowing into the cylinder via the TH / C4 (supply via TH / C) Air volume) decreases. Thereafter, the opening degree of the first ADM / V12 is gradually reduced and the opening degree of the TH / C4 is gradually increased by the processes (feedback process) of steps S70 to S90 and steps S100 to S120 in FIG. In response to this, the supply air amount via the second intake passage gradually decreases, and the supply air amount via TH / C gradually increases.

  By controlling as described above, the EGR gas staying in the intake system is consumed while being diluted by the fresh air introduced through the second intake passage 11, so that the EGR rate in the intake system gradually increases. descend. Thus, the ENG introduction Total EGR rate gradually decreases without increasing as in the comparative example after transitioning to the deceleration state.

  Next, the effects of the above-described embodiment will be summarized.

  In the present embodiment, the internal combustion engine system 100 includes a TH / C 4 disposed on the downstream side of the compressor 5A in the first intake passage 2 and a compressor on the downstream side of the turbine 5B in the first exhaust passage 3 and the first intake passage 2. EGR passage 8 communicating with the upstream side from 5A, and EGR / V10 for adjusting the flow rate of exhaust gas passing through EGR passage 8 are provided. Further, the internal combustion engine system 100 includes a second intake passage 11 that communicates the downstream side of the first intake passage 2 with respect to TH / C4 and the upstream side with respect to the merged portion of the EGR passage 8 of the first intake passage 2 with a second intake passage 11. The first ADM / V 12 is provided in the intake passage 11. Further, the internal combustion engine system 100 is disposed in the second intake passage 11 and prevents backflow that opens when the internal pressure of the first intake passage 2 downstream of TH / C4 becomes lower than the internal pressure of the second intake passage 11. A valve 13 and a controller 20 that controls TH / C4 in the closing direction when the vehicle is decelerated are provided.

  Since the EGR gas staying in the first intake passage 2 does not flow back through the second intake passage 11 by providing the backflow prevention valve 13, if the first intake passage internal pressure becomes lower than the second intake passage internal pressure. It becomes possible to quickly supply fresh air into the cylinder, and the deterioration of the combustion stability in the deceleration state can be suppressed. As a result, the EGR rate in the running state other than the deceleration state can be set higher, so that the fuel consumption performance can be improved. In addition, since the high pressure is continuously applied to the backflow prevention valve 13 in the supercharging region, if a butterfly valve is used, there is a problem in durability, and there is a risk that intake air leaks into the second intake passage 11. However, according to the backflow prevention valve 13 of the present embodiment, it is possible to reliably prevent intake air from leaking into the second intake passage 11 and to ensure durability.

  Furthermore, if the backflow prevention valve 13 is disposed at the junction of the first intake passage 2 and the second intake passage 11 on the downstream side of TH / C4, EGR gas does not stay in the second intake passage 11, and more quickly. New air can be supplied into the cylinder.

  In this embodiment, if the change amount (reduction amount) of the required EGR rate is equal to or greater than a predetermined amount, that is, if the second intake passage 11 and the backflow prevention valve 13 are not provided, misfire occurs due to deterioration in combustion stability. In the deceleration state in which the required EGR rate changes to such a degree that the possibility of occurrence of this occurs, the controller 20 controls TH / C4 in the closing direction. Thereby, the deterioration of the combustion stability in a deceleration state can be suppressed.

  According to the present embodiment, since the first air flow meter 14 is provided in the first intake passage 2, the amount of intake air flowing through the first intake passage 2 can be directly detected.

(Second Embodiment)
FIG. 6 is a schematic configuration diagram of an internal combustion engine system 100 according to the second embodiment. The difference from the configuration of FIG. 1 is that the second intake passage 11 includes a second air flow meter 15 as a second intake air amount acquisition device, and the first intake passage 2 has an O as an exhaust gas recirculation rate acquisition device. It is a point provided with ₂ sensors 16. Due to this difference, the detected value of the second air flow meter 15 is read in step S80 of FIG. 2, and the detected value of the second air flow meter 15 is subtracted from the detected value of the first air flow meter 14 in step S110. The amount of air in the first intake passage is acquired.

  In the configuration in which the second intake passage 11 branches from the first intake passage 2 as shown in FIG. 6, when the required air amount is controlled in a minute state as in deceleration, the air passing through each intake passage It is important to accurately detect the amount. In this regard, in the present embodiment, the amount of air in the second intake passage is directly detected, and the amount of air in the first intake passage is determined using the detection value of the first air flow meter 14 and the detection value of the second air flow meter 15. Since it can be calculated, it is possible to accurately detect the air amount in the first intake passage and the air amount in the second intake passage. As a result, the accuracy of the feedback control of the first ADM / V12 and TH / C4 becomes higher.

  As described above, in this embodiment, since the second air flow meter 15 is provided in the second intake passage 11 in addition to the first air flow meter 14, the amount of air passing through the second intake passage 11 is directly detected. It is possible to control with higher accuracy.

In the present embodiment, in order to acquire the EGR rate of the first intake passage 2, the O ₂ sensor (exhaust gas recirculation rate acquisition device) 16 is provided in the first intake passage 2. The EGR rate can be detected more accurately. As a result, the opening degrees of the first ADM / V12 and TH / C4 can be more accurately controlled so that the required air amount of the internal combustion engine 1 is obtained.

(Third embodiment)
FIG. 7 is a schematic configuration diagram of an internal combustion engine system 100 according to the third embodiment.

  The difference from the second embodiment is that one end of the second intake passage 11 is not connected to the upstream side of the merging portion of the first intake passage 2 with the EGR passage 8 and is independent of the first intake passage 2. It is a point that has become a qi introduction port. The opening / closing control of the first ADM / V12 and TH / C4 is the same as in the second embodiment.

  When TH / C4 is controlled in the closing direction during the operation of the internal combustion engine 1, a pressure wave in a direction of flowing back from the TH / C4 through the first intake passage 2 is generated, and the EGR gas remaining in the first intake passage 2 Flows backward in the first intake passage 2 and flows upstream. In the configuration of FIGS. 1 and 6, when the backflowed EGR gas flows into the second intake passage 11, the EGR remaining in the first intake passage 2 due to the fresh air introduced from the second intake passage 11. The effect of diluting the gas will fade. In contrast, in the configuration of the present embodiment, one end of the second intake passage 11 is a fresh air inlet that is independent of the first intake passage 2, so that the backflowed EGR gas flows into the second intake passage 11. No new air is supplied from the second intake passage 11.

  As described above, in the present embodiment, since one end of the second intake passage 11 is a fresh air inlet independent of the first intake passage 2, the first wave is generated by the pressure wave generated by closing TH / C4. Even if the EGR gas flows backward through the intake passage 2, only fresh air can be supplied from the second intake passage 11. As a result, the control of consuming the EGR gas staying in the first intake passage 2 while being decelerated by the fresh air introduced from the second intake passage 11 in the deceleration state can be executed with higher accuracy.

(Fourth embodiment)
FIG. 8 is a schematic configuration diagram of an internal combustion engine system 100 according to the fourth embodiment. The difference from the second embodiment is that the second intake throttle valve is a second intake throttle valve on the upstream side of the junction with the EGR passage 8 of the first intake passage 2 and on the downstream side of the junction with the second intake passage 11. An admission valve (second ADM / V) 19 is provided. The controller 20 controls TH / C4 in the closing direction and also controls the second ADM / V19 in the closing direction when the vehicle is decelerated.

  In the configuration of the present embodiment, one end of the second intake passage 11 is connected to the first intake passage 2, but even if the EGR gas flows backward when TH / C4 is controlled in the closing direction, the second ADM / V19 is also Since it is controlled in the closing direction, the inflow of EGR gas to the second intake passage 11 can be suppressed. That is, the same effect as the third embodiment can be obtained.

(Fifth embodiment)
FIG. 9 is a schematic configuration diagram of an internal combustion engine system 100 according to the fifth embodiment. The difference from the fourth embodiment is that a second exhaust passage 17 that communicates between the compressor 5A of the first intake passage 2 and TH / C4 and the downstream of the turbine 5B of the first exhaust passage 3 is provided. The exhaust flow rate adjusting valve 18 for opening and closing the second exhaust passage 17 is provided. The exhaust flow rate adjusting valve 18 is controlled to open and close by a controller 20.

  When the controller 20 executes the processing of steps S60 to S90 and S100 to S120 in FIG. 2, that is, when the change amount of the required EGR rate is large enough to cause a deceleration and a risk of misfire, 18 is opened. As a result, the EGR gas staying in the intake system can be quickly discharged to the first exhaust passage 3, so that it is possible to suppress delays in response and deterioration of operability when the vehicle is reaccelerated immediately after shifting to the deceleration state. Further, in the first and second embodiments, by slightly opening TH / C4, the EGR gas staying in the intake system is consumed while diluted with fresh air introduced from the second intake passage 11. However, in this embodiment, if TH / C4 is fully closed, it is possible to supply only fresh air to the internal combustion engine 1 to improve combustion stability.

  As described above, in the present embodiment, the second exhaust that communicates the upstream of TH / C4 of the first intake passage 2 and the downstream of the junction with the EGR passage 8 and the downstream of the turbine 5B of the first exhaust passage 17. A passage 17 and an exhaust flow rate adjustment valve 18 for opening and closing the second exhaust passage 17 are further provided. Then, the controller 20 controls TH / C4 in the closing direction and opens the exhaust flow rate adjusting valve 18 when the deceleration state is reached. As a result, the EGR gas staying in the upstream side of the first intake passage 2 particularly in the upstream side of TH / C4 can be discharged quickly. For example, even when there is a reacceleration request immediately after the deceleration request, a response delay or The drivability deterioration can be suppressed. Further, if the exhaust flow rate adjustment valve 18 is opened and the TH / C 4 is fully closed in the deceleration state, only fresh air can be supplied to the internal combustion engine 1 to improve combustion stability.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 1st intake passage 3 1st exhaust passage 4 Throttle chamber 5 Turbocharger 7 Exhaust gas purification device 8 EGR passage 10 EGR valve 11 2nd intake passage 12 Admission valve 13 Backflow prevention valve 14 1st air flow meter 15 Second air flow meter 16 O ₂ sensor 17 Second exhaust passage 18 Exhaust flow rate adjustment valve 19 Second admission valve 20 Controller

Claims (5)

A turbocharger,
A first intake passage in which a compressor of the turbocharger is disposed;
A first exhaust passage in which a turbine of the turbocharger is disposed;
A throttle chamber disposed downstream of the compressor in the first intake passage;
An exhaust gas recirculation passage communicating the downstream side of the turbine of the first exhaust passage and the upstream side of the compressor of the first intake passage;
An exhaust gas recirculation amount control valve for adjusting an exhaust gas flow rate passing through the exhaust gas recirculation passage;
One end of the first intake passage is connected to the upstream side of the junction with the exhaust gas recirculation passage, or is a fresh air inlet different from the first intake passage, and the other end is the first intake passage. A second intake passage connected downstream of the throttle chamber of the intake passage;
A first intake throttle valve disposed in the second intake passage;
The second intake passage is disposed downstream of the first intake throttle valve, and opens when the internal pressure of the first intake passage downstream of the throttle chamber is lower than the internal pressure of the second intake passage. A valve,
When the exhaust gas recirculation amount control valve is opened / closed in response to a vehicle deceleration request, the total EGR rate becomes higher than the misfire limit EGR rate , and the least air in a range where no misfire occurs when the valve is closed The total EGR rate after controlling the opening degree of the throttle chamber so as to obtain the amount and controlling the opening and closing of the exhaust gas recirculation amount control valve in response to the vehicle deceleration request becomes higher than the misfire limit EGR rate , and When the valve is opened, a control unit for controlling the throttle chamber in the closing direction and controlling the first intake throttle valve in the opening direction;
An internal combustion engine system comprising:
One end of the second intake passage is connected to the upstream side of the junction with the exhaust gas recirculation passage of the first intake passage,
A second intake throttle valve provided upstream of the compressor of the first intake passage and downstream of a junction with the second intake passage;
The control unit controls the second intake throttle valve in the closing direction when a total EGR rate after opening / closing the exhaust gas recirculation amount control valve in response to the vehicle deceleration request becomes higher than a misfire limit EGR rate. An internal combustion engine system. A turbocharger,
  A first intake passage in which a compressor of the turbocharger is disposed;
  A first exhaust passage in which a turbine of the turbocharger is disposed;
  A throttle chamber disposed downstream of the compressor in the first intake passage;
  An exhaust gas recirculation passage communicating the downstream side of the turbine of the first exhaust passage and the upstream side of the compressor of the first intake passage;
  An exhaust gas recirculation amount control valve for adjusting an exhaust gas flow rate passing through the exhaust gas recirculation passage;
  One end of the first intake passage is connected to the upstream side of the junction with the exhaust gas recirculation passage, or is a fresh air inlet different from the first intake passage, and the other end is the first intake passage. A second intake passage connected downstream of the throttle chamber of the intake passage;
  A first intake throttle valve disposed in the second intake passage;
  The second intake passage is disposed downstream of the first intake throttle valve, and opens when the internal pressure of the first intake passage downstream of the throttle chamber is lower than the internal pressure of the second intake passage. A valve,
  When the exhaust gas recirculation amount control valve is opened / closed in response to a vehicle deceleration request, the total EGR rate becomes higher than the misfire limit EGR rate, and the least air in a range where no misfire occurs when the valve is closed The total EGR rate after controlling the opening degree of the throttle chamber so as to obtain the amount and controlling the opening and closing of the exhaust gas recirculation amount control valve in response to the vehicle deceleration request becomes higher than the misfire limit EGR rate, and When the valve is opened, a control unit for controlling the throttle chamber in the closing direction and controlling the first intake throttle valve in the opening direction;
An internal combustion engine system comprising:
  A second exhaust passage that communicates the first intake passage upstream from the throttle chamber and downstream from the junction with the exhaust gas recirculation passage, and the first exhaust passage downstream from the turbine;
  An exhaust flow rate adjusting valve for opening and closing the second exhaust passage;
Further comprising
  The control unit opens the exhaust flow rate adjustment valve when a total EGR rate after the exhaust recirculation amount control valve is controlled to open and close in response to the vehicle deceleration request becomes higher than a misfire limit EGR rate. Internal combustion engine system. The internal combustion engine system according to claim 1 or 2 ,
An internal combustion engine system comprising a first intake air amount acquisition device for acquiring an intake air amount flowing through the first intake passage in the first intake passage. The internal combustion engine system according to any one of claims 1 to 3 ,
An internal combustion engine system comprising a second intake air amount acquisition device for acquiring an intake air amount flowing through the second intake passage in the second intake passage. The internal combustion engine system according to any one of claims 1 to 4 ,
An internal combustion engine system comprising an exhaust gas recirculation rate acquisition device for acquiring an exhaust gas recirculation rate in the first intake passage.

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