JP2019002396A - Egr control device of engine with supercharger - Google Patents

Abstract

To accurately control an EGR gas flow rate without using an exclusive pressure sensor specially irrespective of a variation of an opening of an intake valve.SOLUTION: A low-pressure loop-type EGR device 21 of an engine 1 having a supercharger 5 includes an EGR passage 22 and an EGR valve 23. A throttle valve 6a is arranged in an intake passage 2 at a downstream side of a compressor 5a, and an intake valve 28 is arranged in an intake passage 2 at an upstream side of an outlet 22b of the EGR passage 22. An electronic control device 50 full-close controls the EGR valve 23 at a cut of deceleration fuel, full-open controls the intake valve 28, controls the throttle valve 6a to a sonic opening, acquires an actual opening of the throttle valve 6a on the basis of an intake amount which is detected at that time, and a prescribed valve passage flow rate fundamental formula, corrects the control of the throttle valve 6a on the basis of a throttle opening correction value which is learnt from a difference between its actual opening and a prescribed opening, similarly acquires an actual opening of the intake valve 28, and corrects the control of the intake valve 28 on the basis of an intake opening correction value which is learnt from a difference between its actual opening and a prescribed opening.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to a low-pressure loop EGR device provided in an engine equipped with a supercharger, and relates to an EGR control device for a supercharged engine configured to control the EGR device.

  Conventionally, as this type of technique, for example, a technique described in Patent Document 1 below is known. This technique includes a low-pressure loop EGR device provided in an engine equipped with a supercharger. This EGR device adjusts the EGR passage for flowing a part of the exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage upstream of the compressor of the supercharger, and the EGR gas flow rate in the EGR passage. An EGR valve, an intake valve provided in an intake passage upstream from the outlet of the EGR passage, a pressure sensor for detecting a pressure between the intake valve and the EGR valve, and a predetermined interval between the upstream and downstream of the EGR valve And an electronic control unit (ECU) for controlling the intake valve based on the detected pressure so that a pressure difference within the range is formed. According to this device, since the ECU controls the intake valve based on the detected pressure so that a pressure difference within a predetermined range is formed before and after the EGR valve, a desired pressure difference is formed before and after the EGR valve. As a result, the required flow rate of EGR gas could be stably supplied to the engine.

JP 2008-248729 A

  By the way, in the technique described in Patent Document 1, since there is some opening variation (including manufacturing variation within a tolerance, change with time) in the intake valve, the opening variation acts on the outlet of the EGR passage. There was a risk of variations in negative pressure. On the other hand, since the EGR valve also has some opening variation (including manufacturing variations within tolerance, including changes over time), there is a possibility that the EGR gas flow rate passing through the EGR valve may vary due to the opening variation. It was. In addition, the opening variation of the intake valve and the opening variation of the EGR valve may have a combined effect on the EGR gas flow rate. Therefore, simply controlling the intake valve and the EGR valve may deteriorate the control accuracy of the EGR gas flow rate. Further, in the technique of Patent Document 1, since a pressure sensor is used to control the suction valve, the cost is increased accordingly. In addition, the pressure sensor may be affected by EGR gas.

  This disclosed technique has been made in view of the above circumstances, and its purpose is to accurately control the EGR gas flow rate without using a dedicated pressure sensor regardless of variations in the opening of the intake valve. It is an object of the present invention to provide an EGR control device for an internal combustion engine with a supercharger that makes it possible. Another object of the disclosed technique is to provide a supercharger capable of accurately controlling the EGR gas flow rate without using a dedicated pressure sensor regardless of variations in the opening degree of the suction valve and the EGR valve. To provide an EGR control device for an internal combustion engine.

In order to achieve the above object, the technology described in claim 1 is provided in an intake passage and an exhaust passage of an engine, a supercharger for boosting intake air in the intake passage, and the supercharger in the intake passage. An engine including an arranged compressor, a turbine arranged in an exhaust passage, a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable, and a part of exhaust discharged from the engine to the exhaust passage as EGR gas The EGR passage and the EGR passage that flow to the intake passage to recirculate to the exhaust passage are connected to the exhaust passage downstream of the turbine and connected to the intake passage upstream of the compressor and the EGR passage in the EGR passage. An EGR valve for adjusting the gas flow rate and an intake air for adjusting the amount of intake air flowing through the intake passage provided in the intake passage downstream of the compressor An intake valve that is provided in the intake passage upstream from the outlet of the EGR passage and that restricts the intake air amount that flows through the intake passage, and the intake air amount detection that detects the intake air amount that flows through the intake passage upstream from the intake valve And a control means for controlling at least the EGR valve, the intake air amount adjustment valve and the intake valve, the control means controls the EGR valve to be fully closed and suction The intake air amount detected by the intake air amount detecting means when the valve is controlled to be fully opened and the intake air amount adjusting valve is controlled to a predetermined opening so that the intake air passing through the intake air amount adjusting valve has a sound speed, and Based on the basic equation (F) of the valve passage flow shown, the actual opening degree related to the intake air amount adjusting valve is obtained, and the opening degree correction value of the intake air amount adjusting valve is calculated from the difference between the obtained actual opening degree and the predetermined opening degree. To the learned opening correction value Hazuki corrected control of the intake air flow control valve,
dm = A · Cq · Cm · Pup / √Tup (F)
dm: intake air amount, A: valve opening area, Cq: valve flow coefficient, Cm: valve flow coefficient, Pup: pressure upstream of the valve, Tup: temperature control means upstream of the valve was learned After correcting the control of the intake air amount adjustment valve based on the opening amount correction value of the intake air amount adjustment valve, the intake air amount detection means when the EGR valve is controlled to be fully closed and the intake valve is controlled to close to a predetermined opening degree. Based on the detected intake air amount and the basic equation (F), an actual opening degree related to the intake valve is obtained, and an opening correction value of the intake valve is calculated from a difference between the obtained actual opening degree and a predetermined opening degree of the intake valve. And the control of the intake valve is corrected based on the learned opening correction value.

  According to the configuration of the above technique, the control unit performs the correction control as described above. Therefore, since the control of the intake air amount adjustment valve and the control of the intake valve are corrected without using a dedicated pressure sensor for detecting the pressure downstream of the intake valve, when the EGR valve is opened The flow rate of the EGR gas flowing into the intake passage is corrected regardless of whether there is any variation in the intake valve opening.

In order to achieve the above object, the technology described in claim 2 is provided in an intake passage and an exhaust passage of an engine, a supercharger for boosting intake air in the intake passage, and a supercharger in the intake passage. An engine including an arranged compressor, a turbine arranged in an exhaust passage, a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable, and a part of exhaust discharged from the engine to the exhaust passage as EGR gas The EGR passage and the EGR passage that flow to the intake passage to recirculate to the exhaust passage are connected to the exhaust passage downstream of the turbine and connected to the intake passage upstream of the compressor and the EGR passage in the EGR passage. An EGR valve for adjusting the gas flow rate and an intake air for adjusting the amount of intake air flowing through the intake passage provided in the intake passage downstream of the compressor An intake valve that is provided in the intake passage upstream from the outlet of the EGR passage and that restricts the intake air amount that flows through the intake passage, and the intake air amount detection that detects the intake air amount that flows through the intake passage upstream from the intake valve And an EGR control device for an engine with a supercharger comprising at least an EGR valve, an intake air amount adjustment valve, and a control means for controlling the intake valve. Detected by the intake air amount detection means when the intake valve is controlled to fully open and the intake valve is fully opened, and the intake air amount adjustment valve is controlled to a predetermined opening so that the intake air passing through the intake air amount adjustment valve has a sound speed. On the basis of the intake air amount and the basic equation (F) of the valve passage flow rate shown below, the actual opening degree of the intake air amount adjustment valve is obtained, and the intake air amount adjustment is performed from the difference between the obtained actual opening degree and the predetermined opening degree. Learning valve opening correction value To correct the control of the intake air amount adjusting valve based on the learned degree of opening correction value,
dm = A · Cq · Cm · Pup / √Tup (F)
dm: intake air amount, A: valve opening area, Cq: valve flow coefficient, Cm: valve flow coefficient, Pup: pressure upstream of the valve, Tup: temperature control means upstream of the valve At the time of fuel cut, after correcting the intake air amount adjustment valve control based on the learned intake air amount adjustment valve opening correction value, the EGR valve is controlled to be fully closed and the intake valve is controlled to close to a predetermined opening Based on the intake air amount detected by the intake air amount detecting means and the basic equation (F), an actual opening degree related to the intake valve is obtained, and from the difference between the obtained actual opening degree and the predetermined opening degree of the intake valve. The purpose is to learn the opening correction value of the intake valve and to correct the control of the intake valve based on the learned opening correction value.

  According to the configuration of the above technique, the control means executes the correction control as described above when the engine deceleration fuel cut. Therefore, since the control of the intake air amount adjustment valve and the control of the intake valve are corrected without using a dedicated pressure sensor for detecting the pressure downstream of the intake valve, when the EGR valve is opened The flow rate of the EGR gas flowing into the intake passage is corrected regardless of whether there is any variation in the intake valve opening.

  According to the first aspect of the present invention, the EGR gas flow rate can be accurately controlled without using a dedicated pressure sensor regardless of variations in the opening of the intake valve.

  According to the second aspect of the present invention, the EGR gas flow rate can be accurately controlled without using a dedicated pressure sensor regardless of variations in the opening of the intake valve.

1 is a schematic configuration diagram showing a gasoline engine system according to an embodiment. The flowchart which shows the content of EGR correction control concerning one Embodiment. The conceptual diagram which shows the state of the throttle valve in a throttle opening measurement mode, an EGR valve, and an intake valve concerning one Embodiment. The conceptual diagram which concerns on one Embodiment and shows a throttle opening map. The conceptual diagram which shows the state of the throttle valve in a suction valve opening degree measurement mode, an EGR valve, and a suction valve concerning one Embodiment. The graph which shows the relationship between the ratio of the downstream pressure with respect to the pressure of the upstream of a certain valve | bulb, and a flow coefficient concerning one Embodiment. The conceptual diagram which shows the state of the throttle valve in a EGR valve opening degree measurement mode, an EGR valve, and an intake valve concerning one Embodiment. According to one embodiment, master opening, flow velocity, measurement items (intake air) related to throttle opening correction (event (1)), intake opening correction (event (2)), and EGR opening correction (event (3)) (Amount) and a table showing specific items. The time chart which shows an example of the behavior of the various parameters regarding EGR correction control concerning one Embodiment.

  Hereinafter, an embodiment in which an EGR control device for an engine with a supercharger is embodied in a gasoline engine system will be described in detail with reference to the drawings.

[About engine system overview]
In FIG. 1, a gasoline engine system (hereinafter simply referred to as “engine system”) mounted on an automobile includes an engine 1 having a plurality of cylinders. The engine 1 is a 4-cylinder, 4-cycle reciprocating engine, and includes well-known components such as a piston and a crankshaft. The engine 1 is provided with an intake passage 2 for introducing intake air to each cylinder and an exhaust passage 3 for deriving exhaust gas from each cylinder of the engine 1. A supercharger 5 is provided in the intake passage 2 and the exhaust passage 3. The intake passage 2 is provided with an intake inlet 2a, an air cleaner 4, a compressor 5a of the supercharger 5, an electronic throttle device 6, an intercooler 7 and an intake manifold 8 in order from the upstream side.

  The electronic throttle device 6 is disposed in the intake passage 2 upstream of the intake manifold 8 and is opened and closed according to the driver's accelerator operation, thereby adjusting the amount of intake air flowing through the intake passage 2. In this embodiment, the electronic throttle device 6 is constituted by a DC motor type motor-operated valve. The throttle valve 6a is driven to open and close, and a throttle sensor 41 for detecting the opening degree (throttle opening degree) TA of the throttle valve 6a. Including. The electronic throttle device 6 corresponds to an example of an intake air amount adjustment valve in the disclosed technology. The intake manifold 8 is disposed immediately upstream of the engine 1 and includes a surge tank 8a into which intake air is introduced, and a plurality (four) of branches for distributing the intake air introduced into the surge tank 8a to each cylinder of the engine 1. Tube 8b. In the exhaust passage 3, an exhaust manifold 9, a turbine 5b of the supercharger 5, and a catalyst 10 are provided in this order from the upstream side. The catalyst 10 is for purifying exhaust gas, and can be composed of, for example, a three-way catalyst.

  The supercharger 5 is provided for boosting the intake air in the intake passage 2, and can integrally rotate the compressor 5 a disposed in the intake passage 2, the turbine 5 b disposed in the exhaust passage 3, and the compressor 5 a and the turbine 5 b. And a rotating shaft 5c connected to the shaft. The turbine 5b is rotated by the exhaust gas flowing through the exhaust passage 3, and the compressor 5a is rotated in conjunction with the rotation, so that the intake air flowing through the intake passage 2 is boosted. The intercooler 7 cools the intake air boosted by the compressor 5a.

  The engine 1 is provided with a fuel injection device (not shown) for injecting fuel corresponding to each cylinder. The fuel injection device is configured to inject fuel supplied from a fuel supply device (not shown) into each cylinder of the engine 1. In each cylinder, a combustible air-fuel mixture is formed by the fuel injected from the fuel injection device and the intake air introduced from the intake manifold 8.

  The engine 1 is provided with an ignition device (not shown) corresponding to each cylinder. The ignition device is configured to ignite a combustible mixture formed in each cylinder. The combustible air-fuel mixture in each cylinder explodes and burns by the ignition operation of the ignition device, and the exhaust after combustion is discharged to the outside from each cylinder through the exhaust manifold 9, the turbine 5b, and the catalyst 10. At this time, a piston (not shown) moves up and down in each cylinder, and a crankshaft (not shown) rotates, whereby power is obtained for the engine 1.

  The engine system of this embodiment includes a low-pressure loop type exhaust gas recirculation device (EGR device) 21. The EGR device 21 is a device for flowing a part of the exhaust discharged from each cylinder to the exhaust passage 3 as exhaust gas recirculation gas (EGR gas) to the intake passage 2 to recirculate to each cylinder of the engine 1. An exhaust gas recirculation passage (EGR passage) 22 for flowing EGR gas from the passage 3 to the intake air passage 2 and an exhaust gas recirculation valve (EGR valve) 23 for adjusting the flow rate of the EGR gas in the EGR passage 22 are provided. The EGR passage 22 includes an inlet 22a and an outlet 22b. An inlet 22a of the EGR passage 22 is connected to the exhaust passage 3 downstream of the catalyst 10, and an outlet 22b of the passage 22 is connected to the intake passage 2 upstream of the compressor 5a. Further, an EGR cooler 24 for cooling the EGR gas is provided in the EGR passage 22 upstream from the EGR valve 23.

  In this embodiment, the EGR valve 23 is constituted by a DC motor type motor-operated valve, and includes a valve body 23a that is driven in a variable opening degree. The EGR valve 23 desirably has characteristics of a large flow rate, high response, and high resolution. Therefore, in this embodiment, as the structure of the EGR valve 23, for example, a “double eccentric valve” described in Japanese Patent No. 5759646 can be adopted. This double eccentric valve is configured for large flow control.

  In this engine system, the EGR valve 23 opens in a supercharging region where the supercharger 5 operates (a region where the intake air amount is relatively large). Thereby, a part of the exhaust gas flowing through the exhaust passage 3 flows into the EGR passage 22 from the inlet 22a as EGR gas, and flows into the intake passage 2 via the EGR cooler 24 and the EGR valve 23, and the compressor 5a, electronic throttle The refrigerant is returned to each cylinder of the engine 1 via the device 6, the intercooler 7 and the intake manifold 8.

  In this embodiment, an intake valve 28 for adjusting the flow area of the passage 2 is provided in the intake passage 2 downstream of the air cleaner 4 and upstream of the outlet 22 b of the EGR passage 22. In this embodiment, the suction valve 28 is constituted by a DC motor type electric valve and includes a butterfly valve 28a that is driven to open and close. When the EGR gas is introduced from the outlet 22b of the EGR passage 22 into the intake passage 2, the intake valve 28 reduces the opening of the butterfly valve 28a in order to make the intake air near the outlet 22b negative pressure. Yes.

[Electric configuration of engine system]
As shown in FIG. 1, various sensors 41 to 47 provided in the engine system correspond to an example of an operation state detection unit for detecting the operation state of the engine 1. An air flow meter 42 provided in the vicinity of the air cleaner 4 detects the intake air amount Ga flowing from the air cleaner 4 to the intake passage 2 and outputs an electric signal corresponding to the detected value. The air flow meter 42 corresponds to an example of an intake air amount detection unit in the disclosed technology. The intake pressure sensor 43 provided in the surge tank 8a detects the intake pressure PM downstream from the electronic throttle device 6 and outputs an electrical signal corresponding to the detected value. The water temperature sensor 44 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the engine 1 and outputs an electrical signal corresponding to the detected value. A rotation speed sensor 45 provided in the engine 1 detects the rotation speed of the crankshaft as the rotation speed (engine rotation speed) NE of the engine 1 and outputs an electric signal corresponding to the detected value. The oxygen sensor 46 provided in the exhaust passage 3 detects the oxygen concentration (output voltage) Ox in the exhaust discharged to the exhaust passage 3 and outputs an electrical signal corresponding to the detected value. An accelerator sensor 47 is provided on the accelerator pedal 16 provided in the driver's seat. The accelerator sensor 47 detects the depression angle of the accelerator pedal 16 as the accelerator opening ACC, and outputs an electrical signal corresponding to the detected value.

  The engine system includes an electronic control unit (ECU) 50 that performs various controls. Various sensors 41 to 47 are respectively connected to the ECU 50. The ECU 50 is connected to the electronic throttle device 6, the EGR valve 23, the intake valve 28, and the like.

  In this embodiment, the ECU 50 inputs various signals output from various sensors 41 to 47, and in order to execute fuel injection control and ignition timing control based on these signals, each injector and each ignition coil are respectively It comes to control. Further, the ECU 50 controls the electronic throttle device 6, the EGR valve 23, and the intake valve 28 in order to execute intake control and EGR control based on various signals.

  Here, the intake control refers to controlling the intake air amount introduced into the engine 1 by controlling the electronic throttle device 6 based on the detected value of the accelerator sensor 47 according to the operation of the accelerator pedal 16 by the driver. It is. The ECU 50 controls the electronic throttle device 6 in the valve closing direction to throttle the intake air when the engine 1 is decelerated. The EGR control is to control the flow rate of EGR gas recirculated to the engine 1 by controlling the EGR valve 23 and the intake valve 28 in accordance with the operating state of the engine 1. The ECU 50 controls the EGR valve 23 to be fully closed when the engine 1 is decelerated in order to shut off the EGR gas to the engine 1 (EGR cut).

  As is well known, the ECU 50 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like. The memory stores a predetermined control program related to various controls of the engine 1. The CPU executes the above-described various controls based on a predetermined control program based on detection values of various sensors 41 to 47 input via the input circuit. In this embodiment, the ECU 50 corresponds to an example of a control unit in the disclosed technology.

  Here, in the EGR device 21 of this embodiment, the intake valve 28 and the EGR valve 23 have some degree of opening degree variation (including manufacturing variation within tolerance and change with time). Further, the negative pressure acting on the outlet 22b of the EGR passage 22 may deviate from the target value due to variations in the opening of the suction valve 28. Furthermore, there is a possibility that the flow rate of the EGR gas flowing out from the EGR passage 22 to the intake passage 2 may deviate from the target value due to the opening degree variation of the EGR valve 23. Therefore, when the ECU 50 executes the EGR control, the control accuracy of the EGR gas flow rate may be deteriorated. Therefore, in this embodiment, the ECU 50 executes the following EGR correction control in order to improve the control accuracy of the EGR gas flow rate regardless of the opening degree variation of the intake valve 28 and the opening degree variation of the EGR valve 23. It is like that.

[EGR correction control]
FIG. 2 is a flowchart showing the contents of the EGR correction control. When the processing shifts to this routine, in step 100, the ECU 50 takes in the throttle opening TA, the intake pressure PM, and the engine rotational speed NE from the detection values of the throttle sensor 41, the intake pressure sensor 43, and the rotational speed sensor 45, respectively.

  Next, at step 110, the ECU 50 determines whether or not the operation of the engine 1 is a deceleration fuel cut. That is, it is determined whether or not the fuel supply to the engine 1 is cut off when the engine 1 is decelerated. If this determination result is negative, ECU 50 returns the process to step 100, and if this determination result is affirmative, the process proceeds to step 120.

  In step 120, the ECU 50 determines whether or not the intake air passing through the electronic throttle device 6 (throttle valve 6a) becomes sonic. That is, it is determined whether or not the intake air passing through the throttle valve 6a at the time of deceleration fuel cut becomes a sonic speed. The ECU 50 can make this determination based on the intake pressure PM. The ECU 50 returns the process to step 100 if the determination result is negative, and proceeds to step 130 if the determination result is affirmative.

  In step 130, the ECU 50 determines whether or not the throttle opening correction for the throttle valve 6a has been completed. The ECU 50 proceeds to step 140 when the determination result is negative, and proceeds to step 190 when the determination result is affirmative.

  In step 140, the ECU 50 executes a throttle opening measurement mode process for the throttle valve 6a. FIG. 3 is a conceptual diagram showing states of the throttle valve 6a, the EGR valve 23, and the suction valve 28 at this time. That is, as shown in FIG. 3, the ECU 50 sets the master opening of the throttle valve 6 a to a predetermined value (for example, “7 deg”), fully opens the master opening of the suction valve 28 (“90 deg”), and sets the EGR valve 23. The master opening is fully closed (“0%”). At this time, the intake air passing through the throttle valve 6a has a sonic velocity, and the pressure on the upstream side of the throttle valve 6a is almost atmospheric pressure (known).

  Next, at step 150, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 42. Here, since the intake air passing through the throttle valve 6a has a sound velocity, the intake air amount Ga detected by the air flow meter 42 shows a stable and constant value even if the engine rotational speed NE slightly varies.

Next, at step 160, the ECU 50 calculates an actual opening (throttle actual opening) TAR related to the throttle valve 6a based on the detected intake air amount Ga and the basic equation (F) of the valve passage flow shown below. To do.
dm = A · Cq · Cm · Pup / √Tup (F)
In step 160, “dm” in the basic formula (F) means an intake air amount Ga (mass flow rate) and is known. “A” means the opening area of the throttle valve 6a and has product variations. “Cq” means the flow coefficient of the throttle valve 6a and is known. “Cm” means the flow coefficient of the throttle valve 6a and is known in the sonic region. “Pup” means the pressure on the upstream side of the throttle valve 6a and is known as atmospheric pressure. “Tup” means the temperature on the upstream side of the throttle valve 6a and is known as the atmospheric temperature. Therefore, from the basic formula (F), the opening area A when the throttle valve 6a is set to a predetermined master opening can be specified from the relationship between the intake air amount Ga (dm) and the sonic velocity region. From this, the actual throttle opening degree TAR can be obtained. Here, since the intake air has a sound velocity, the opening area A can be accurately obtained, and thus the actual throttle opening degree TAR can be accurately obtained.

  Next, at step 170, the ECU 50 learns the throttle opening correction value TAC. That is, the difference between the actual throttle opening degree TAR and the master opening degree of the throttle valve 6a is obtained as the throttle opening correction value TAC and stored in the memory.

  Next, in step 180, the ECU 50 executes throttle opening correction. That is, the ECU 50 corrects the predetermined throttle opening map value with the throttle opening correction value TAC. FIG. 4 is a conceptual diagram showing a throttle opening map. As shown in FIG. 4, there is generally a product variation VA in the relationship of the flow rate with respect to the throttle opening. Here, for example, the target value TVC after correction can be obtained by subtracting the throttle opening correction value TAC from the target value TV before correction. By correcting the throttle opening map in this way, it is possible to eliminate opening variation and changes over time due to product tolerances of the throttle valve 6a.

  Then, when the throttle opening correction is completed at step 180 and the routine proceeds from step 130 to step 190, the ECU 50 determines whether or not the intake opening correction regarding the intake valve 28 is completed. The ECU 50 proceeds to step 200 if the determination result is negative, and proceeds to step 250 if the determination result is affirmative.

  In step 200, the ECU 50 executes the processing of the suction opening degree measurement mode related to the suction valve 28. FIG. 5 is a conceptual diagram showing states of the throttle valve 6a, the EGR valve 23, and the suction valve 28 at this time. That is, as shown in FIG. 5, the ECU 50 sets the corrected opening of the throttle valve 6a to a predetermined value (for example, “equivalent to 7 degrees”), and sets the master opening of the intake valve 28 to a predetermined value (for example, “8 degrees”). The master opening of the EGR valve 23 is fully closed (“0%”). At this time, the intake air passing through the throttle valve 6a has a sound velocity, and the pressure on the upstream side of the intake valve 28 becomes the atmospheric pressure (known).

  Next, at step 210, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 42. Here, since the intake air passing through the throttle valve 6a has a sound velocity, the intake air amount Ga detected by the air flow meter 42 shows a stable constant value.

  Next, in step 220, the ECU 50 can calculate the actual opening (intake actual opening) ADR of the intake valve 28 based on the detected intake air amount Ga and the basic equation (F) described above. In step 220, “dm” in the basic formula (F) means the intake air amount Ga and is known. “A” means the opening area of the intake valve 28 and has product variations. “Cq” means the flow coefficient of the suction valve 28 and is known. “Cm” means the flow coefficient of the suction valve 28 and can be obtained from the relationship between the pressure (Pdn) on the downstream side of the suction valve 28 (suction negative pressure) “Pdn” and the pressure “Pup” on the upstream side. FIG. 6 is a graph showing the relationship between the ratio “Pdn / Pup” of the downstream pressure “Pdn” to the upstream pressure “Pup” of a valve and the flow coefficient “Cm”. From this graph, the flow coefficient “Cm” of the suction valve 28 can be specified. “Pup” in the basic formula (F) means the pressure on the upstream side of the intake valve 28 and is known as atmospheric pressure. “Pdn” corresponds to the pressure “Pup” on the upstream side of the throttle valve 6a. This “Pup” can be obtained by applying the basic formula (F) to the throttle valve 6a. The opening area A of the throttle valve 6 a is known at step 170. Further, “dm”, “Tup”, and “Cq” are each known. Further, in the throttle valve 6a, “Cm” is known because the intake air has a sound velocity. “Pup” can be calculated using these values. Therefore, from the basic formula (F), the opening area A when the suction valve 28 is set to the predetermined master opening can be specified, and the actual suction opening ADR can be obtained thereby.

  Next, at step 230, the ECU 50 learns the suction opening correction value ADC. That is, the difference between the actual suction opening ADR and the master opening of the suction valve 28 is obtained as the suction opening correction value ADC and stored in the memory.

  Next, in step 240, the ECU 50 executes suction opening correction. That is, the ECU 50 corrects the suction opening map value by the suction opening correction value ADC. For example, the corrected target value can be obtained by adding or subtracting the suction opening correction value ADC to the target value before correction. By correcting the suction opening map in this way, it is possible to eliminate opening variation and changes over time due to product tolerances of the suction valve 28.

  When the suction opening correction is completed in step 240 and the routine proceeds from step 190 to step 250, the ECU 50 determines whether or not the EGR opening correction for the EGR valve 23 is completed. The ECU 50 proceeds to step 260 when the determination result is negative, and returns the process to step 100 when the determination result is affirmative.

  In step 260, the ECU 50 executes the processing in the EGR opening degree measurement mode 1 related to the EGR valve 23. That is, as similar to FIG. 5, the ECU 50 sets the corrected opening of the throttle valve 6 a to a predetermined value (for example, “7 deg equivalent”), and sets the corrected opening of the intake valve 28 to a predetermined value (for example “8 deg equivalent”). ), And the master opening of the EGR valve 23 is fully closed (“0%”) as the first opening. At this time, the intake air that passes through the throttle valve 6a has a sonic velocity, and the intake air that passes through the intake valve 28 has a subsonic velocity.

  Next, in step 270, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 42. Also here, since the intake air passing through the throttle valve 6a has a sound velocity, the intake air amount Ga detected by the air flow meter 42 is a stable and constant value.

  Next, in step 280, the ECU 50 executes processing in the EGR opening degree measurement mode 2 related to the EGR valve 23. FIG. 7 is a conceptual diagram showing the states of the throttle valve 6a, the EGR valve 23, and the intake valve 28 at this time. That is, as shown in FIG. 7, the ECU 50 sets the corrected opening of the throttle valve 6a to a predetermined value (for example, “equivalent to 7 degrees”), and sets the corrected opening of the intake valve 28 to a predetermined value (for example, “equivalent to 8 degrees”). Then, the master opening degree of the EGR valve 23 is opened from a fully closed state to a predetermined value (for example, “25%”) as the second opening degree. At this time, the intake air that passes through the throttle valve 6a has a sonic velocity, the intake air that passes through the intake valve 28 has a subsonic velocity, and the EGR gas that has passed through the EGR valve 23 has a subsonic velocity.

  Next, at step 290, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 42. Also here, since the intake air passing through the throttle valve 6a has a sound velocity, the intake air amount Ga detected by the air flow meter 42 is a stable and constant value.

  Next, in step 300, the ECU 50 uses the pressure difference (front-rear differential pressure) between the upstream pressure and the downstream pressure of the EGR valve 23 and the EGR gas flow rate passing through the EGR valve 23 to The actual opening (EGR actual opening) EAR is calculated. Here, the pressure downstream of the intake valve 28 (also downstream of the EGR valve 23) when the intake valve 28 reaches a predetermined post-correction opening (for example, “equivalent to 8 deg”) is known (can be estimated with high accuracy). Since the upstream pressure of the EGR valve 23 is substantially the atmospheric pressure when the engine 1 is decelerating fuel cut, the differential pressure across the EGR valve 23 is known. Further, the flow rate of the EGR gas passing through the EGR valve 23 can be obtained from the amount of change in the intake air amount Ga in step 290 with respect to the intake air amount Ga in step 270. From the relationship between the differential pressure across the EGR valve 23, the EGR gas flow rate, the flow coefficient, and the flow coefficient, the opening area when the EGR valve 23 is set to a predetermined master opening (for example, “25%”) can be specified. Thus, the EGR actual opening EAR can be obtained.

  Next, at step 310, the ECU 50 learns the EGR opening correction value EAC. That is, the difference between the EGR actual opening EAR and the master opening of the EGR valve 23 is obtained as the EGR opening correction value EAC and stored in the memory.

  Next, in step 320, the ECU 50 executes EGR opening correction. That is, the ECU 50 corrects the EGR opening degree map value with the EGR opening degree correction value EAC. For example, the corrected target value can be obtained by adding or subtracting the EGR opening correction value EAC to the target value before correction. By correcting the EGR opening degree map in this way, it is possible to eliminate opening degree variations and changes over time due to product tolerances of the EGR valve 23.

  When the EGR opening correction is completed at step 320, the ECU 50 returns the process from step 250 to step 100.

  Here, FIG. 8 shows “master opening” relating to “throttle opening correction” (event (1)), “suction opening correction” (event (2)) and “EGR opening correction” (event (3)). "Degree", "flow velocity", "measurement item (intake air amount)" and "specific item" are arranged in one table. As shown in FIG. 8, in the throttle opening correction of event (1), the throttle opening is set to “7 (including error) deg” which is the master opening, and the suction opening is set to “90 deg” which is the master opening. In addition, the EGR opening is set to “0%” which is the master opening. The flow velocity at this time is “sound speed” in the throttle valve 6 a and “subsonic speed” in the suction valve 28. The measurement item (intake amount) is “absolute flow rate”. The specific item is “the opening area of the throttle valve 6a”. Further, in the suction opening correction of event (2), the throttle opening is set to “7 deg equivalent” which is the corrected opening, and the intake opening is set to “8 (including error) deg” which is the master opening. Set the opening to “0%”, which is the master opening. The flow velocity at this time is “sound speed” in the throttle valve 6 a and “subsonic speed” in the suction valve 28. The measurement item (intake air amount) is “absolute flow rate”. Further, the specific items are “suction negative pressure” and “opening area of the suction valve 28”. Further, in the EGR opening correction of the event (3), the EGR opening is set to “equivalent to 7 deg” which is the opening after correcting the throttle opening, and “equivalent to 8 deg” which is the opening after correcting the suction opening. Is set to “25 (including error)%” which is the master opening degree. The flow velocity at this time is “sound speed” in the throttle valve 6 a, “subsonic speed” in the suction valve 28, and “subsonic speed” in the EGR valve 23. Further, the measurement item (intake air amount) is “change flow rate from event (2)”. Furthermore, the specific item is “opening area of EGR valve 23”.

  FIG. 9 is a time chart showing an example of behavior of various parameters related to EGR correction control. In FIG. 9, (a) to (c) are parameters for determining the deceleration fuel cut (F / C), (a) is the rotational speed NE, (b) is the accelerator opening ACC, (c ) Indicates the presence or absence of a fuel cut F / C. (D) shows events (1) to (3) ((1): throttle opening correction, (2): intake opening correction, (3): EGR opening correction), (e) shows event timer Showing change. (F) to (h) show changes in various reference openings, (f) shows the throttle opening, (g) shows the intake opening, and (h) shows the EGR opening. (I) to (l) indicate completion of opening degree correction, (i) indicates an intake air amount Ga, (j) indicates a throttle valve, (k) indicates an intake valve, and (l) indicates an EGR valve. .

  In FIG. 9, first, at time t1, for example, when the accelerator opening degree ACC becomes “0” at an engine speed NE of “800 rpm” or more, a deceleration fuel cut is determined. Then, from time t1, the throttle opening correction of the event (1) is started, and the time measurement of the event timer is started. In order to correct the throttle opening, the master opening MO with a throttle opening of “7 deg”, the master opening MO with an intake opening of “90 deg”, and the master opening with an EGR opening of “0%” Set to MO respectively. Here, the throttle opening correction starts at time t1 and is completed at time t4. In the meantime, when a predetermined time (for example, “0.5 seconds”) elapses after the event timer starts measuring, data measurement of the intake air amount Ga and the like is started at time t2, and the data measurement is ended at time t3. At this time, the intake air amount Ga decreases from time t1, and thereafter becomes a constant value until time t5.

  When the throttle opening correction is completed at time t4, the suction opening correction for event (2) is started from time t4, and the event timer is started again. At this time, in order to correct the intake opening, the corrected opening CO with the throttle opening of “equivalent to 7 deg” is set to the master opening MO with the intake opening of “8 deg”, and the EGR opening is “0%”. Set to the master opening MO. Here, the suction opening correction starts at time t4 and is completed at time t5. Meanwhile, the intake air amount Ga continuously becomes a constant value.

  Thereafter, when the suction opening correction is completed at time t5, the EGR opening correction of event (3) is started from time t5, and the event timer is started again. At this time, in order to correct the EGR opening, the throttle opening is the corrected opening CO corresponding to “7 deg”, the corrected opening CO where the suction opening is “equivalent to 8 deg”, and the EGR opening is “25%”. "Is set to the master opening degree MO. Here, the EGR opening correction starts at time t5 and is completed at time t6. Meanwhile, the intake air amount Ga decreases once and becomes a constant value. The amount of change dmegr of the intake air amount at this time corresponds to the EGR gas flow rate when the EGR opening is set to “25%”. When the EGR opening correction is completed at time t6, after time t6, in order to monitor the target flow rate of EGR gas, the throttle opening is equal to the corrected opening CO with “equivalent to 7 deg”, and the intake opening is The post-correction opening degree CO corresponding to “8 deg” is set to the post-correction opening degree CO corresponding to “25%”.

  Therefore, as shown in FIG. 9, the throttle opening correction, the intake opening correction, and the EGR opening correction are executed between time t1 and time t6 when the operation of the engine 1 is decelerated fuel cut.

  According to the EGR control device for an engine with a supercharger in this embodiment described above, the ECU 50 executes the above-described EGR correction control when the engine 1 is in operation. In this EGR correction control, the ECU 50 controls the EGR valve 23 to be fully closed and the intake valve 28 to be fully open when the engine 1 is decelerating fuel cut so that the intake air passing through the throttle valve 6a becomes the sonic velocity. The throttle valve 6a is controlled to a predetermined opening. At this time, the ECU 50 obtains the actual throttle opening degree TAR related to the throttle valve 6a based on the intake air amount Ga detected by the air flow meter 42 and the basic equation (F) of the predetermined valve passage flow rate, and the actual throttle opening degree. The throttle opening correction value TAC of the throttle valve 6a is learned from the difference between the TAR and a predetermined master opening, and the control of the throttle valve 6a is corrected based on the learned throttle opening correction value TAC. Further, the ECU 50 continuously corrects the control of the throttle valve 6a based on the learned throttle opening correction value TAC when the engine 1 is decelerating fuel cut, and then controls the EGR valve 23 to be fully closed and the intake valve 28. The valve is closed to a predetermined opening. At this time, the ECU 50 obtains the actual intake opening ADR related to the intake valve 28 based on the intake air amount Ga detected by the air flow meter 42 and the basic equation (F), and the actual intake opening ADR and the intake valve 28 The suction opening correction value ADC of the suction valve 28 is learned from the difference from the predetermined master opening, and the control of the suction valve 28 is corrected based on the learned suction opening correction value ADC. Therefore, according to this EGR correction control, the control of the throttle valve 6a and the control of the intake valve 28 are corrected without using any special pressure sensor for detecting the pressure Pdn on the downstream side of the intake valve 28. Therefore, when the EGR valve 23 is opened, the flow rate of the EGR gas flowing into the intake passage 2 is corrected regardless of whether the opening degree of the intake valve 28 varies. For this reason, the EGR gas flow rate can be accurately controlled without using a dedicated pressure sensor regardless of the opening degree variation of the intake valve 28.

  Further, in the EGR correction control of this embodiment, the ECU 50 continues to correct the control of the throttle valve 6a and correct the control of the intake valve 28 when the engine 1 is decelerating fuel cut, and then the EGR valve 23 is changed to a predetermined first. The valve opening is controlled from one opening (for example, “0%”) to a predetermined second opening (for example, “25%”), and the amount of change in the intake air amount Ga detected by the air flow meter 42 at that time is changed to the first opening Is determined as the amount of change in the flow rate of the EGR gas with respect to the change in the opening from the first to the second opening. Further, the pressure difference between the upstream pressure and the downstream pressure of the EGR valve 23 when the EGR valve 23 is controlled to open to the second opening is obtained. Then, an EGR actual opening degree EAR relating to the EGR valve 23 is obtained based on the obtained flow rate change amount and the pressure difference, and an EGR opening correction value of the EGR valve 23 is obtained from the difference between the EGR actual opening degree EAR and the second opening degree. EAC is learned, and the control of the EGR valve 23 is corrected based on the learned EGR opening correction value EAC. Therefore, according to this EGR correction control, the control of the EGR valve 23 is further corrected without using any special pressure sensor for detecting the pressure on the downstream side of the suction valve 28. Therefore, the EGR valve 23 When the valve is opened, the flow rate of the EGR gas flowing into the intake passage 2 is further corrected regardless of the presence or absence of variations in the opening of the EGR valve 23. For this reason, it becomes possible to control the EGR gas flow rate more accurately without using a dedicated pressure sensor, regardless of variations in the opening degrees of the suction valve 28 and the EGR valve 23.

  That is, according to the configuration of this embodiment, the actual values of the throttle valve 6a, the intake valve 28, and the EGR valve 23 are based on the intake air amount Ga detected by the air flow meter 42 and the basic equation (F) of the valve passage flow rate. The difference between the opening (the actual throttle opening TAR, the actual suction opening ADR, the EGR actual opening EAR) and the predetermined various master openings is calculated, and the control of the various valves 6a, 28, 23 is corrected to the tolerance center. As a result, variations in the EGR gas flow rate can be reduced. Specifically, in a predetermined mode running test using an actual vehicle, if the target EGR rate in the variation of the EGR rate is “25 ± 1 (%)”, in this embodiment, the variation range of the EGR rate is “2 (%). " It can be seen that this is superior to the variation range “9 (%)” of the EGR rate when the control of the various valves 6 a, 28, and 23 is not corrected.

  Note that the disclosed technology is not limited to the above-described embodiment, and a part of the configuration can be changed as appropriate without departing from the spirit of the disclosed technology.

  (1) In the above embodiment, the throttle opening correction, the intake opening correction, and the EGR opening correction are executed in the EGR correction control. However, in the EGR correction control, the EGR opening correction is omitted and the throttle opening correction is performed. It is also possible to configure so as to execute only the opening correction and the intake valve opening correction.

  (2) In the above-described embodiment, the throttle opening correction, the intake opening correction, and the EGR opening correction are continuously executed as a series of events (1) to (3) when the engine 1 decelerates fuel. Although configured, the throttle opening correction, the intake opening correction, and the EGR opening correction may be executed separately at different deceleration fuel cuts.

  (3) In the above-described embodiment, in an ordinary gasoline engine vehicle, “EGR correction control” is performed when the engine 1 is decelerating fuel cut and the intake air passing through the electronic throttle device 6 (throttle valve 6a) is sonic. Configured to run when. In contrast, in an ordinary gasoline engine vehicle or a hybrid vehicle equipped with an engine and a motor, “EGR correction control” is executed when the intake air passing through the electronic throttle device becomes sonic regardless of when the engine deceleration fuel is cut. It can also be configured to. For example, in an ordinary gasoline engine vehicle or a “parallel type” or “split type” hybrid vehicle, when the engine is in steady operation and the intake air passing through the electronic throttle device becomes sonic, “EGR correction control” Can also be configured to execute. Alternatively, in the “series system” hybrid vehicle, “EGR correction control” may be executed when the intake air passing through the electronic throttle device becomes sonic. Here, the “parallel method” is a method in which both the engine and the motor are used for driving the wheels. The “split method” is a method in which power from an engine is divided by a power dividing mechanism and distributed to a generator and wheels, or driving forces from the engine and motor are appropriately combined. The “series system” is a system that uses an engine only for power generation, uses a motor only for driving and regenerating an axle, and has a storage battery for collecting electric power. That is, the “series system” hybrid vehicle can be said to be an electric vehicle equipped with an engine as a power source for power generation.

  This disclosed technique can be used for a low-pressure loop EGR device provided in an engine equipped with a supercharger.

1 Engine 2 Intake Passage 3 Exhaust Passage 5 Supercharger 5a Compressor 5b Turbine 5c Rotating Shaft 6 Electronic Throttle Device (Intake Amount Control Valve)
6a Throttle valve 21 EGR device 22 EGR passage 22a Inlet 22b Outlet 23 EGR valve 28 Suction valve 42 Air flow meter (intake amount detection means)
50 ECU (control means)

Claims (2)

A turbocharger provided in an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An EGR passage that flows to the intake passage to recirculate a part of the exhaust discharged from the engine to the exhaust passage as EGR gas to the engine;
The EGR passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An EGR valve for adjusting the flow rate of EGR gas in the EGR passage;
An intake air amount adjusting valve provided in the intake passage downstream of the compressor, for adjusting the intake air amount flowing through the intake passage;
An intake valve that is provided in the intake passage upstream of the outlet of the EGR passage and restricts the amount of intake air flowing through the intake passage;
An intake air amount detecting means for detecting an intake air amount flowing through the intake passage upstream from the intake valve, and an excess control means for controlling at least the EGR valve, the intake air amount adjusting valve, and the intake valve. In an EGR control device for an engine with a feeder,
The control means controls the EGR valve to be fully closed and the intake valve to be fully open, and further sets the intake air amount adjustment valve to a predetermined opening so that the intake air passing through the intake air amount adjustment valve has a sound speed. Based on the intake air amount detected by the intake air amount detecting means at the time of control and the basic equation (F) of the valve passage flow rate shown below, an actual opening degree related to the intake air amount adjustment valve is obtained and obtained. Learning the opening correction value of the intake air amount adjustment valve from the difference between the actual opening and the predetermined opening, correcting the control of the intake air amount adjustment valve based on the learned opening correction value,
dm = A · Cq · Cm · Pup / √Tup (F)
dm: intake air amount, A: valve opening area, Cq: valve flow coefficient, Cm: valve flow coefficient, Pup: pressure upstream of the valve, Tup: temperature upstream of the valve The control means is learned After correcting the control of the intake air amount adjustment valve based on the opening correction value of the intake air amount adjustment valve, the EGR valve is controlled to be fully closed and the intake valve is controlled to close to a predetermined opening degree. Then, based on the intake air amount detected by the intake air amount detecting means and the basic formula (F), an actual opening degree relating to the intake valve is obtained, and the obtained actual opening degree and the predetermined opening degree of the intake valve are obtained. An EGR control apparatus for an engine with a supercharger, which learns an opening correction value of the intake valve from a difference from the degree, and corrects the control of the intake valve based on the learned opening correction value. A turbocharger provided in an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An EGR passage that flows to the intake passage to recirculate a part of the exhaust discharged from the engine to the exhaust passage as EGR gas to the engine;
The EGR passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An EGR valve for adjusting the flow rate of EGR gas in the EGR passage;
An intake air amount adjusting valve provided in the intake passage downstream of the compressor, for adjusting the intake air amount flowing through the intake passage;
An intake valve that is provided in the intake passage upstream of the outlet of the EGR passage and restricts the amount of intake air flowing through the intake passage;
An intake air amount detecting means for detecting an intake air amount flowing through the intake passage upstream from the intake valve, and an excess control means for controlling at least the EGR valve, the intake air amount adjusting valve, and the intake valve. In an EGR control device for an engine with a feeder,
The control means controls the EGR valve to be fully closed and the intake valve to be fully open at the time of deceleration fuel cut of the engine, and further controls the intake air so that the intake air passing through the intake air amount adjustment valve has a sound speed. Based on the intake air amount detected by the intake air amount detecting means when the amount adjusting valve is controlled to a predetermined opening and the following basic expression (F) of the valve passage flow rate, An opening degree is obtained, an opening correction value of the intake air amount adjustment valve is learned from a difference between the obtained actual opening degree and the predetermined opening degree, and the intake air amount adjustment valve is based on the learned opening degree correction value. Correct the control of
dm = A · Cq · Cm · Pup / √Tup (F)
dm: intake air amount, A: valve opening area, Cq: valve flow coefficient, Cm: valve flow coefficient, Pup: pressure upstream of the valve, Tup: temperature upstream of the valve The control means is the engine At the time of deceleration fuel cut, after correcting the control of the intake air amount adjustment valve based on the learned opening correction value of the intake air amount adjustment valve, the EGR valve is controlled to be fully closed and the intake valve is opened to a predetermined degree. Based on the intake air amount detected by the intake air amount detecting means and the basic equation (F), the actual opening degree related to the intake valve is obtained, and the obtained actual opening degree is determined. And a suction opening correction value of the suction valve is learned from a difference between the suction valve and the predetermined opening of the suction valve, and the control of the suction valve is corrected based on the learned opening correction value. EGR control device for engine with aircraft.

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