JP4631719B2 - Engine control system - Google Patents

Description

  The present invention relates to an engine control system for controlling an engine exhaust turbocharger.

  Conventionally, in a turbocharged diesel engine (engine) and a gasoline engine equipped with an exhaust turbocharger (hereinafter referred to as a turbocharger), the exhaust pressure of the turbocharger is VGT (Variable Geometry Turbo) vane opening degree. And it is controlled by the wastegate valve opening. The control amount of the VGT vane opening and the wastegate valve opening is a closed loop with respect to a predetermined target amount (for example, set boost pressure or intake amount) of the intake system based on the engine speed and load. It is determined by control or simple open loop control.

  The conventional control (hereinafter referred to as conventional supercharging control) has a problem that a supercharging delay occurs due to a response delay of the supercharging device under unsteady operation conditions. As a result, problems such as an increase in pumping loss and difficulty in introducing exhaust gas (hereinafter referred to as EGR) gas occur.

  As described above, in the conventional supercharging control, the engine speed response of the turbocharger is large in a non-steady state, that is, when the fluctuation of the engine speed is large, such as racing in a no-load vehicle or sudden acceleration in a low gear. It did not consider the delay and the accompanying increase in exhaust pressure. Furthermore, since most of the actual driving conditions are in an unsteady operation state, under the above operating conditions, the differential pressure between the supercharging pressure and the exhaust pressure increases due to the response delay of the supercharging device, and the pumping loss increases. As a result, the actual driving fuel consumption is deteriorated.

  Various proposals have been made so far regarding the problem of the conventional supercharging control. For example, Patent Document 1 obtains the rates of increase of the intake pressure and the exhaust pressure, respectively, and controls the vane opening of the turbocharger turbine based on the ratios thereof. As a result, the exhaust pressure is suppressed below a predetermined pressure, and a significant increase in exhaust pressure during unsteady operation can be suppressed.

Japanese Patent Publication No. 7-49771

  However, as described above, the control considering the exhaust pressure increase as in Patent Document 1 is performed when the exhaust pressure increase is delayed by a certain amount or more with respect to the boost pressure increase under unsteady operation conditions. Since the control is to open the valve, the deterioration of fuel consumption due to the increase in exhaust pressure and the accompanying increase in pumping loss can be suppressed, but the followability with respect to the supercharging condition target value is greatly reduced. That is, it takes time for the boost pressure to increase to the target boost pressure, and exhaust gas performance such as CO and HC and output performance are degraded.

  On the other hand, the conventional supercharging control allows the supercharging condition to reach the target value in a relatively short time and is advantageous in terms of exhaust gas and output characteristics, but the exhaust pressure tends to rise excessively. This will lead to a deterioration in fuel consumption due to an increase in pumping loss.

  As described above, in order to improve the fuel efficiency and the exhaust gas performance at the same time, not only the conventional supercharging control and the control of Patent Document 1, but also the optimal control of the supercharging device including the intermediate state thereof Is desired.

  Therefore, an object of the present invention is to provide an engine control system that can solve the above-described problems and improve fuel efficiency and exhaust gas performance.

  In order to achieve the above object, the present invention adjusts the supercharging pressure of an exhaust turbocharger having a compressor provided in an intake passage of an engine and a turbine provided in an exhaust passage, and the exhaust turbocharger. A supercharging pressure adjusting device for detecting the supercharging pressure of the exhaust turbocharger disposed in the intake passage, and detecting the exhaust pressure of the engine disposed in the exhaust passage An exhaust pressure detecting means for controlling the supercharging pressure, and a supercharging control for controlling the supercharging pressure adjusting device so that the supercharging pressure of the supercharging pressure detecting means becomes a predetermined target supercharging pressure, and the supercharging pressure detecting means Supercharging is performed to obtain the actual pumping loss of the engine from the supercharging pressure and the exhaust pressure of the exhaust pressure detecting means and to control the supercharging pressure adjusting device so that the actual pumping loss becomes a predetermined target pumping loss. A pumping loss for calculating a pumping loss ratio by calculating a permissible upper limit value of the pumping loss from the control means and the operating state of the engine and dividing the actual pumping loss obtained by the supercharging pressure control means by the permissible upper limit value The supercharging pressure control means includes a supercharging pressure control means when the pumping loss ratio calculated by the pumping loss ratio calculating means is greater than or equal to a predetermined pumping loss ratio and less than 1. A control value and an exhaust control value by the exhaust control are calculated, and the supercharging pressure adjusting device is controlled by an intermediate value between the supercharging control value and the exhaust control value.

  Preferably, the supercharging pressure control means controls the supercharging pressure adjusting device with an exhaust control value by the exhaust control when the pumping loss ratio calculated by the pumping loss ratio calculating means is 1 or more. It is.

  Preferably, when the pumping loss ratio calculated by the pumping loss ratio calculating unit is less than the predetermined pumping loss ratio, the supercharging pressure control unit uses the supercharging control value by the supercharging control value by the supercharging control. It controls the adjustment device.

  Preferably, the engine is provided with an exhaust gas recirculation device for circulating a part of the exhaust gas in the exhaust passage to the intake air passage, and the exhaust gas recirculation device is controlled by the supercharging pressure control means, and When performing exhaust gas recirculation, the pressure control means obtains the supercharging pressure and exhaust pressure necessary to achieve the target exhaust gas recirculation rate, calculates the necessary minimum pumping loss from these supercharging pressure and exhaust pressure, and The required minimum pumping loss ratio is calculated by dividing the minimum pumping loss by the allowable upper limit value. When the pumping loss ratio calculated by the pumping loss ratio calculating means is less than the required minimum pumping loss ratio, the required minimum The supercharging pressure adjusting device is controlled by an exhaust control value by the exhaust control in which the pumping loss is the target pumping loss.

  Preferably, an intake air amount detecting means is provided in the intake passage for detecting the intake air amount of the engine, and the supercharging pressure control means performs the supercharging control by setting the intake air amount of the intake air amount detecting means to a predetermined amount. The supercharging pressure adjusting device is controlled to achieve the target intake air amount.

  In order to achieve the above object, the present invention adjusts the supercharging pressure of an exhaust turbocharger having a compressor provided in an intake passage of an engine and a turbine provided in an exhaust passage, and the exhaust turbocharger. A supercharging pressure adjusting device for detecting the supercharging pressure of the exhaust turbocharger disposed in the intake passage, and detecting the exhaust pressure of the engine disposed in the exhaust passage An exhaust pressure detecting means for controlling the supercharging pressure, and a supercharging control for controlling the supercharging pressure adjusting device so that the supercharging pressure of the supercharging pressure detecting means becomes a predetermined target supercharging pressure, and the supercharging pressure detecting means Supercharging is performed to obtain the actual pumping loss of the engine from the supercharging pressure and the exhaust pressure of the exhaust pressure detecting means and to control the supercharging pressure adjusting device so that the actual pumping loss becomes a predetermined target pumping loss. Control means, and an allowable upper limit value calculating means for obtaining an allowable upper limit value of the pumping loss from the operating state of the engine, the supercharging pressure control means, the actual pumping loss is greater than or equal to a predetermined low exhaust pressure pumping loss, And when it is less than the allowable upper limit value calculated by the allowable upper limit value calculating means, the supercharging control value by the supercharging control and the exhaust control value by the exhaust control are calculated respectively, and the supercharging control value and The supercharging pressure adjusting device is controlled by an intermediate value with respect to the exhaust control value.

  According to the present invention, an excellent effect that fuel efficiency and exhaust gas performance can be improved is exhibited.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The engine control system of the present embodiment is applied to, for example, a diesel engine equipped with an EGR device.

  The engine control system will be described based on FIG. 1 and FIG.

  As shown in FIG. 1, the engine control system 1 includes an exhaust turbocharger 5 having a compressor 51 provided in an intake passage 3 of an engine 2 and a turbine (exhaust turbine) 52 provided in an exhaust passage 4, A wastegate device 6 serving as a supercharging pressure adjusting device for adjusting the supercharging pressure of the exhaust turbocharging device 5 and a supercharging pressure of the exhaust turbocharging device 5 disposed in the intake passage 3 are detected. A supercharging pressure sensor 7 serving as a supercharging pressure detecting means, an exhaust pressure sensor 8 disposed in the exhaust passage 4 and serving as an exhaust pressure detecting means for detecting the exhaust pressure of the engine 2, and a supercharging pressure sensor 7 The actual pumping of the engine 2 from the supercharging control for controlling the wastegate device 6 so that the supercharging pressure of the engine 2 becomes a predetermined target supercharging pressure, and the supercharging pressure of the supercharging pressure sensor 7 and the exhaust pressure of the exhaust pressure sensor 8. Ross And a supercharging pressure control means for performing exhaust control for controlling the wastegate device 6 so that the actual pumping loss becomes a predetermined target pumping loss, and obtaining an allowable upper limit value of the pumping loss from the operating state of the engine 2 And a pumping loss ratio calculating means for calculating a pumping loss ratio (actual pumping loss / allowable upper limit value) by dividing the actual pumping loss obtained by the supercharging pressure control means by the allowable upper limit value.

  In FIG. 2, the supercharging pressure control means comprises supercharging control value calculating means 101, exhaust control value calculating means 102, actual pumping loss calculating means 103, allowable upper limit value calculating means 104, and control value determining means 105. The loss ratio calculation means constitutes the necessary minimum pumping loss calculation means 106. In the present embodiment, an engine control device (hereinafter referred to as ECU) 10 described later serves as the supercharging pressure control means and the pumping loss ratio calculation means.

  A plurality of cylinders 21 are formed in the engine 2, and the intake passage 3 and the exhaust passage 4 are connected to the cylinders 21, respectively. In the intake passage 3, an intake air amount sensor 31, a compressor 51 of the exhaust turbocharger 5, an air cooler 32, and a supercharging pressure sensor 7 are provided in order from the upstream side. In the exhaust passage 4, an exhaust pressure sensor 8, an exhaust temperature sensor 41 for detecting the exhaust temperature, and a turbine 52 of the exhaust turbocharger 5 are provided in order from the upstream side. The engine 2 is provided with an engine rotation speed sensor 22 for detecting the rotation speed of the engine 2.

  The exhaust turbocharger 5 is provided with a waste gate device 6. The wastegate device 6 includes a wastegate passage 61 for communicating the inflow side and the outflow side of the turbine 52, and a wastegate valve (in FIG. 1, a wastegate valve control device) 62 that opens and closes the wastegate passage 61. With. The waste gate valve 62 is controlled to open and close by the ECU 10. When the wastegate valve 62 is opened, a part of the exhaust in the exhaust passage 4 upstream from the turbine 52 is bypassed to the exhaust passage 4 downstream from the turbine 52. Thereby, the rotation speed of the turbine 52 falls and the supercharging pressure of the compressor 51 falls.

  In the present embodiment, the engine 2 is provided with an exhaust gas recirculation (hereinafter referred to as EGR) device 9 for circulating a part of the exhaust gas in the exhaust passage 4 to the intake passage 3, and the EGR device 9 is controlled by the ECU 10. The The EGR device 9 cools the EGR passage 91 for communicating the exhaust passage 4 and the intake passage 3, the EGR valve 92 for opening and closing the EGR passage 91, and the exhaust gas (EGR gas) flowing through the EGR passage 91. The EGR cooler 93 is provided. When the EGR valve 92 is opened, a part of the exhaust gas in the exhaust passage 4 is cooled in the EGR cooler 93 and then returned to the intake passage 3. The recirculated exhaust gas is supplied to the engine 2 together with fresh air (supercharged air).

  Further, the engine 2 is provided with an ECU 10 for controlling the engine 2. The ECU 10 is connected to various sensors such as a supercharging pressure sensor 7, an exhaust pressure sensor 8, an intake air amount sensor 31, an engine speed sensor 22, and an exhaust temperature sensor 41, and detection values of these sensors are input. Further, the ECU 10 includes an accelerator opening detected by the accelerator opening sensor 23, a shift position detected by the gear position sensor 24, a fuel injection instruction value calculated by the ECU 10 from an operating state such as an engine speed and a load, and the like. Is entered.

  The ECU 10 is connected to actuators such as the waste gate valve 62 and the EGR valve 92 so as to output a control signal.

  As will be described in detail later, as shown in FIG. 3, the ECU 10 of the present embodiment is basically provided in the exhaust turbocharger 5 by dividing the above-described pumping loss ratio into three regions I to III. The control value (supercharging device control value) of the wastegate device 6 is switched.

  Specifically, when the calculated pumping loss ratio is equal to or greater than a predetermined pumping loss ratio and less than 1 (region II), the ECU 10 determines the supercharging control value by the supercharging control and the exhaust control value by the exhaust control. And the waste gate device 6 is controlled with an intermediate value between the supercharging control value and the exhaust control value. Thereby, in area | region II, a pumping loss can be suppressed compared with supercharging control, and a fuel consumption can be improved. Further, the responsiveness of the exhaust turbocharger 5 can be improved compared to the exhaust control, and the exhaust gas performance of CO, HC, etc. can be improved. Here, the predetermined pumping loss ratio is obtained by dividing a pumping loss (low exhaust pressure pumping loss) that allows an influence on fuel consumption even if an energy loss occurs by an allowable upper limit value. Further, the predetermined pumping loss ratio of the present embodiment is set larger than the necessary minimum pumping loss ratio described later.

  As described above, when the actual pumping loss is equal to or greater than the predetermined low exhaust pressure pumping loss and less than the allowable upper limit value, the ECU 10 determines the supercharging control value by the supercharging control, the exhaust control value by the exhaust control, , And the wastegate device 6 is controlled with an intermediate value between the supercharging control value and the exhaust control value.

  Further, when the calculated pumping loss ratio is 1 or more (region III), the ECU 10 controls the wastegate device 6 with the exhaust control value by the exhaust control. That is, when the actual pumping loss is equal to or greater than the allowable upper limit value, the opening degree of the wastegate valve 62 is controlled based on the actual pumping loss. Thereby, in region III, an excessive increase in the exhaust pressure is suppressed, and energy loss (pumping loss) can be reduced, and fuel efficiency can be improved.

  Further, when the calculated pumping loss ratio is less than the predetermined pumping loss ratio (region I), the ECU 10 controls the supercharging pressure adjusting device with the supercharging control value by the supercharging control. That is, in the region I, the opening degree of the waste gate valve 62 is controlled based on the supercharging pressure. As a result, the supercharging pressure quickly rises to the target supercharging pressure, and response delay can be suppressed, and as a result, exhaust gas performance can be improved.

  The ECU 10 according to the present embodiment basically performs the above-described control. However, when performing EGR, the ECU 10 performs the following control in order to achieve a desired EGR rate.

  When performing the EGR, the ECU 10 obtains a supercharging pressure and an exhaust pressure necessary for achieving the target EGR rate, calculates a necessary minimum pumping loss from the supercharging pressure and the exhaust pressure, and calculates the necessary minimum pumping loss. The necessary minimum pumping loss ratio is calculated by dividing by the allowable upper limit value, and when the pumping loss ratio calculated by the pumping loss ratio calculating means is less than the required minimum pumping loss ratio (area 0), the required minimum The wastegate device 6 is controlled with the exhaust control value by the exhaust control in which the pumping loss is the target pumping loss. As a result, a desired amount of exhaust gas is circulated to the intake side, and the target EGR rate can be reliably achieved.

  Next, the outline of the supercharging device control method by the engine control system 1 of the present embodiment will be described.

  In the supercharging device control method of this embodiment, first, the exhaust pressure of the engine 2 is detected by the exhaust pressure sensor 8.

  Next, using the obtained exhaust pressure and the supercharging pressure (intake pressure) detected by the supercharging pressure sensor 7 (MAP sensor) and the engine speed detected by the engine speed sensor 22, The actual pumping loss occurring in the engine 2 every moment is calculated. Further, the operating state of the engine 2 is detected based on the detection data of various sensors such as the engine rotation speed sensor 22, and the allowable upper limit value of the pumping loss in the operating state is calculated. The supercharging control value is calculated using the supercharging device control logic with the supercharging pressure as a target value or by open loop control. For example, the supercharging control value is calculated by the supercharging control described above. An optimum supercharging condition pumping value in steady operation of the engine 2 is obtained from the engine speed and load, and an exhaust control value is calculated using an exhaust pressure control logic having the optimum supercharging condition pumping value as a target value. For example, the exhaust control value is calculated by the exhaust control described above.

  Next, the calculated actual pumping loss is compared with the allowable upper limit value, and the optimum supercharger control value according to the operating conditions is determined as the supercharging control value, the exhaust control value, the supercharging control value, and Select and decide from intermediate values of exhaust control values.

  Next, an example of supercharging device control executed by the engine control system 1 of the present embodiment will be described based on the flowchart of FIG.

  First, in step S1, the ECU 10 reads the supercharging pressure of the supercharging pressure sensor 7, the exhaust pressure of the exhaust pressure sensor 8, the engine rotation speed of the engine rotation speed sensor 22, and the like.

  Next, in step S2, the ECU 10 calculates the actual pumping loss (PMEPcal) of the engine 2 based on the supercharging pressure, the exhaust pressure, and the engine speed read in step S1. However, the exact value of the pumping loss cannot be obtained unless the internal pressure of the cylinder 21 in the intake / exhaust stroke is analyzed accurately. In other words, the exact pumping loss must be calculated based on the influence of the pulsating pressure and the inertial supercharging caused by the geometry of the intake / exhaust system, the throttle loss due to the change in the effective opening area of the intake / exhaust valve, and the like. However, it is difficult to perform these processes in real time in a normal ECU 10 mounted on the vehicle. Therefore, in the present embodiment, the pumping loss is basically calculated using the supercharging pressure, the exhaust pressure, and the differential pressure thereof, and the calculated pumping loss is corrected by the engine rotation speed, so that an approximate value of the pumping loss is obtained. (PMEPcal) is calculated.

  In step S2, the ECU 10 determines an allowable upper limit value (pumping upper limit value, PMEPmax) for determining how much pumping loss is allowed under the current operating conditions. The following various methods (1) to (3) exist for determining the allowable upper limit value.

  (1) The total allowable energy is evaluated from the engine speed and the fuel flow rate (fuel injection amount instruction value), that is, the amount of fuel injected into the engine 2, and the allowable upper limit so that the energy loss due to the pumping loss is less than a certain percentage. How to determine the value.

  (2) Inferring BMEP (net average effective pressure) from fuel injection command value, injection timing, and intake air amount, and the allowable upper limit so that PMEP (pump loss average effective pressure) due to pumping loss is below a certain percentage of BMEP How to set the value.

  (3) Multiply the pumping loss during normal operation by an appropriate coefficient to calculate the allowable upper limit value, or determine the allowable upper limit value so that the deterioration in fuel consumption due to exhaust pressure rise falls below a certain percentage based on normal operation The allowable upper limit value is given to the ECU 10 as a map in advance.

  Further, in order to set an appropriate allowable upper limit value for various operating states, in addition to the above methods (1) to (3), the accelerator opening change, the fuel injection amount instruction value change rate, the shift position, etc. It is also effective to discriminate sudden acceleration / slow acceleration / quasi-stationary / steady state / deceleration from the above information and correct the allowable upper limit value in each condition.

  Further, in step S2, the ECU 10 obtains a differential pressure (minimum differential pressure) between the supercharging pressure and the exhaust pressure that is required at least to achieve the target EGR rate in each steady operation state. Further, the ECU 10 calculates the pumping loss of the engine 2 at the minimum differential pressure and sets it as the required minimum pumping loss (PMEPmin). In addition, a map showing the relationship between the supercharging pressure and the exhaust pressure and the pumping loss is stored in the ECU 10 in advance, and the necessary minimum is determined from the map and the supercharging pressure and the exhaust pressure at the lowest differential pressure. The pumping loss (PMEPmin) may be read.

  Next, in step S3, the ECU 10 determines a supercharging control value by closed loop or open loop control (supercharging control) targeting the target supercharging pressure. Here, the target boost pressure is obtained based on the operating state of the engine 2 (for example, the fuel injection amount instruction value, the accelerator opening, the shift position, and the engine speed).

  In step S3, the ECU 10 calculates an exhaust control value based on exhaust control using the necessary minimum pumping loss (PMEPmin) as a target value.

  Next, in step S4, the ECU 10 calculates the pumping loss ratio (PMEPcal / PMEPmax) by dividing the actual pumping loss (PMEPcal) obtained in step S2 by the allowable upper limit value (PMEPmax). Further, the ECU 10 calculates a lower limit value X0 of the pumping loss ratio (PMEPcal / PMEPmax). The lower limit value X0 of the present embodiment is a value (PMEPmin / PMEPmax) obtained by dividing the necessary minimum pumping loss by the allowable upper limit value. The ECU 10 determines whether or not the calculated pumping loss ratio (PMEPcal / PMEPmax) exceeds the lower limit value X0 (PMEPmin / PMEPmax).

  Thus, in step S4, a lower limit value X0 (PMEPmin / PMEPmax) is set, and a conditional branch for comparing the magnitude of the lower limit value X0 (PMEPmin / PMEPmax) and the pumping loss ratio (PMEPcal / PMEPmax) is introduced. The reason is to prevent the exhaust pressure from decreasing as the introduction of EGR gas becomes difficult.

  If the pumping loss ratio (PMEPcal / PMEPmax) is equal to or greater than the lower limit value X0 (PMEPmin / PMEPmax) in step S4, the ECU 10 calculates the control value of the wastegate device 6 in step S5 and step S6. As described above, when the pumping loss ratio (PMEPcal / PMEPmax) is equal to or higher than the lower limit value X0 (PMEPmin / PMEPmax) (close to the lower limit value X0), the exhaust pressure rises due to the response delay of the turbocharger, and the fuel consumption deteriorates accordingly. Is judged to be a necessary minimum.

  In step S5 and step S6, when the pumping loss ratio (PMEPcal / PMEPmax) is not less than the predetermined pumping loss ratio X1 and less than 1 (region II in FIG. 3), the ECU 10 determines the supercharging control value and the exhaust gas determined in step S3. The wastegate valve 62 is controlled to open and close with an intermediate value from the control value. Under actual unsteady operation conditions, most of the pumping loss ratio (PMEPcal / PMEPmax) calculated in step S4 falls within the range of the predetermined pumping loss ratio X1 to less than 1. Further, the predetermined pumping loss ratio X1 is obtained by an experiment or the like, for example.

  In step S5 and step S6, when the pumping loss ratio (PMEPcal / PMEPmax) is 1 or more (region III in FIG. 3), the ECU 10 controls the opening and closing of the wastegate valve 62 with the exhaust control value obtained in step S3. To do. In this case, it is determined that there is a concern that the exhaust pressure rises excessively and causes fuel consumption deterioration. Therefore, in order to suppress the pumping loss (pump loss), the exhaust control value is prioritized and the control value of the wastegate valve 62 is selected.

  In step S5 and step S6, the ECU 10 determines that the pumping loss ratio (PMEPcal / PMEPmax) is not less than the lower limit value X0 (PMEPmin / PMEPmax) and less than the predetermined pumping loss ratio X1 (region I in FIG. 3), step S3. The wastegate valve 62 is controlled to open and close with the supercharging control value obtained in step (1). In this case, control of the wastegate valve 62 is performed with priority given to the supercharging control value that quickly reaches the target value (target supercharging pressure) in the supercharging condition (for example, supercharging pressure) without considering the exhaust pressure. Select a value.

  On the other hand, if the pumping loss ratio (PMEPcal / PMEPmax) is less than the lower limit value X0 (PMEPmin / PMEPmax) in step S4, the wastegate valve 62 is controlled to open and close with the exhaust control value obtained in step S3. The present invention is not limited to this, and when the pumping loss ratio (PMEPcal / PMEPmax) is less than the lower limit value X0 (PMEPmin / PMEPmax), the exhaust pressure increase control by the exhaust pressure increase device is performed. Also good. For example, it is conceivable that an inflow amount adjusting vane is provided in the inflow nozzle of the turbine 52 to form an exhaust pressure increasing device, and the inflow amount adjusting vane is throttled to increase the exhaust pressure.

  Next, selection of the control value of the waste gate valve 62 will be described in detail with reference to FIGS. Line C in FIG. 3 shows the relationship of the control gravity center value to the pumping loss ratio (PMEPcal / PMEPmax). The line T1, line T2, and line T3 in FIG. 4 show the relationship of the control value with respect to the control gravity center value. Lines T <b> 1 to T <b> 3 are appropriately selected according to the operating state, performance, etc. of the engine 2.

  The ECU 10 reads the control gravity center value from the output conversion map as shown in FIG. 3 based on the pumping loss ratio (PMEPcal / PMEPmax) calculated in step S4. Next, based on the read control center-of-gravity value, an exhaust control value, a supercharging control value, or an intermediate value between the exhaust control value and the supercharging control value is selected from a supercharging device control conversion map as shown in FIG. To do. Since the intermediate value is based on the value weighted by the output conversion map, an optimal value is taken between the exhaust control value and the supercharging control value.

  For example, when the pumping loss ratio is in the region II (in the case of x in FIG. 3), the control gravity center value is c0, and any one of t1, t2, and t3 is selected as the control value. In the case of region I, the control gravity center value is 0, and the supercharging control value is selected as the control value. In the case of region III, the control center-of-gravity value is 1, and the exhaust control value is selected as the control value.

  The final supercharger control value determined in the above procedure is an optimal control value that takes into account engine performance due to the supercharging condition change speed and exhaust pressure rise, and at the same time stabilizes the introduction of EGR effective for exhaust gas countermeasures. This is the control value that is possible.

  As described above, in the present embodiment, the exhaust pressure supplied to the supercharging device is controlled by the wastegate valve 62 in consideration of the exhaust change at the time of the unsteady operation. Fuel economy can be improved.

  Further, unlike the conventional supercharging device control, in this embodiment, the actual pumping loss occurring in the actual machine is calculated and monitored, and the optimum control value of the wastegate valve 62 is selected, so that the non-steady state It is possible to minimize a decrease in the characteristic (for example, responsiveness) of the change in the supercharging condition when the operating condition changes. As a result, the exhaust gas performance of CO, HC, etc. can be improved.

  In particular, when the pumping loss ratio is in the region II, by appropriately selecting an intermediate control value between the boost pressure control value and the exhaust control value, the deterioration of fuel consumption due to an increase in pumping loss can be achieved in a wider range of operation than before. Can be reduced under conditions.

  In addition, since the pumping loss is controlled so as to keep the optimum setting close to the steady condition, the supercharging pressure and exhaust pressure conditions (for example, the differential pressure between the supercharging pressure and the exhaust pressure) during non-steady operation are more than conventional. It is also possible to improve the introduction of EGR.

  As described above, in the engine control system of the present embodiment, it is possible to reduce CO and HC by improving the supercharging pressure response and to reduce NOx by EGR.

  Next, another embodiment will be described with reference to FIG.

  The present embodiment is different from the above-described embodiment of FIG. 1 in the exhaust turbocharger and the boost pressure regulator, and is otherwise the same. Accordingly, the same elements as those in the above-described embodiment are given the same reference numerals in the drawings, and detailed description thereof is omitted.

  The exhaust turbocharger 71 of this embodiment has a variable capacity turbine 72 instead of the wastegate device. The variable capacity turbine 72 includes, for example, a vane (not shown) that is provided at an inflow portion of the variable capacity turbine 72 and makes the inflow area variable. The vane is controlled to be opened and closed by the ECU 10. In the present embodiment, the exhaust turbocharger 71 forms a supercharging pressure adjustment device.

  Also in this embodiment, the same effect as the above-described embodiment can be obtained.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, an intake air amount detecting means (for example, an intake air amount sensor 31) for detecting the intake air amount of the engine 2 is provided in the intake passage 3, and the ECU 10 serving as a supercharging pressure control means performs the supercharging control. The supercharging pressure adjusting device (specifically, a wastegate valve or a vane of a variable capacity turbine) may be controlled so that the intake air amount of the intake air amount detecting means becomes a predetermined target intake air amount.

  In the above-described embodiment, the exhaust pressure is detected by the exhaust pressure sensor 8, but the present invention is not limited to this. For example, the intake air amount (intake air flow rate) of the intake air amount sensor 31, the supercharging pressure of the supercharging pressure sensor 7, and the operating flow rate for the compressor 51 and the turbine 52 are grasped using the EGR rate detection means, and the exhaust temperature is estimated or Detected by the exhaust temperature sensor 41, the operating efficiency and operating speed (turbo speed) of the compressor 51 are obtained from the intake air flow rate and the operating pressure ratio of the compressor 51, and the turbine operation corrected flow rate is determined from the intake air flow rate, EGR gas flow rate and exhaust temperature. May be calculated, the estimated expansion ratio and the operation efficiency may be calculated from the turbine operation correction flow rate and the turbo rotation speed, and the exhaust pressure may be inferred and detected therefrom.

  Further, instead of the exhaust pressure sensor 8, a differential pressure detecting means (for example, a differential pressure sensor) for detecting the differential pressure between the supercharging pressure and the exhaust pressure is provided in the intake passage 3 and the exhaust passage 4. Also good. In this case, the exhaust pressure is obtained by the difference between the detection value of the supercharging pressure sensor 7 and the detection value of the differential pressure sensor (supercharging pressure sensor 7 detection value−differential pressure sensor detection value).

FIG. 1 is a configuration diagram of an engine control system according to an embodiment of the present invention. FIG. 2 is a diagram for explaining supercharging device control by the engine control system of the present embodiment. FIG. 3 is a diagram showing an example of an output conversion map used in supercharging device control by the engine control system of the present embodiment. FIG. 4 is a diagram showing an example of a supercharging device control value conversion map used in supercharging device control by the engine control system of the present embodiment. FIG. 5 is a diagram illustrating an example of a flowchart of supercharging device control by the engine control system of the present embodiment. FIG. 6 is a configuration diagram of an engine control system according to another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine control system 2 Engine 3 Intake passage 4 Exhaust passage 5 Exhaust turbocharger 6 Wastegate device (supercharging pressure adjustment device)
7 Supercharging pressure sensor (Supercharging pressure detection means)
8 Exhaust pressure sensor (exhaust pressure detection means)
9 EGR device (exhaust gas recirculation device)
10 ECU (supercharging pressure control means, pumping loss ratio calculation means)
51 Compressor 52 Turbine

Claims (6)

An exhaust turbocharger having a compressor provided in the intake passage of the engine and a turbine provided in the exhaust passage;
A supercharging pressure adjusting device for adjusting the supercharging pressure of the exhaust turbo supercharging device;
A supercharging pressure detecting means arranged in the intake passage for detecting a supercharging pressure of the exhaust turbocharger;
An exhaust pressure detecting means disposed in the exhaust passage for detecting the exhaust pressure of the engine;
A supercharging control for controlling the supercharging pressure adjusting device to set the supercharging pressure of the supercharging pressure detecting means to a predetermined target supercharging pressure; and a supercharging pressure and an exhaust pressure detecting means of the supercharging pressure detecting means. A supercharging pressure control means for performing exhaust control for determining the actual pumping loss of the engine from the exhaust pressure and controlling the supercharging pressure adjusting device so that the actual pumping loss becomes a predetermined target pumping loss;
A pumping loss ratio calculating unit that calculates an allowable upper limit value of the pumping loss from the operating state of the engine and calculates a pumping loss ratio by dividing the actual pumping loss determined by the supercharging pressure control unit by the allowable upper limit value; With
The supercharging pressure control means includes
When the pumping loss ratio calculated by the pumping loss ratio calculating means is not less than a predetermined pumping loss ratio and less than 1,
Calculating a supercharging control value based on the supercharging control and an exhaust control value based on the exhaust control, and controlling the supercharging pressure adjusting device with an intermediate value between the supercharging control value and the exhaust control value. An engine control system characterized by The supercharging pressure control means includes
The engine control system according to claim 1, wherein when the pumping loss ratio calculated by the pumping loss ratio calculating means is 1 or more, the supercharging pressure adjusting device is controlled by an exhaust control value by the exhaust control. The supercharging pressure control means includes
3. The supercharging pressure adjusting device is controlled by a supercharging control value by the supercharging control when the pumping loss ratio calculated by the pumping loss ratio calculating means is less than the predetermined pumping loss ratio. Engine control system. The engine is provided with an exhaust gas recirculation device for circulating part of the exhaust gas in the exhaust passage to the intake air passage, and the exhaust gas recirculation device is controlled by the supercharging pressure control means,
The supercharging pressure control means, when performing the exhaust gas recirculation,
Obtain the supercharging pressure and exhaust pressure required to achieve the target exhaust gas recirculation rate, calculate the necessary minimum pumping loss from these supercharging pressure and exhaust pressure, and divide the necessary minimum pumping loss by the above allowable upper limit value. To calculate the required minimum pumping loss ratio,
When the pumping loss ratio calculated by the pumping loss ratio calculating means is less than the required minimum pumping loss ratio,
The engine control system according to any one of claims 1 to 3, wherein the supercharging pressure adjusting device is controlled by an exhaust control value by the exhaust control in which the required minimum pumping loss is the target pumping loss. An intake air amount detection means disposed in the intake passage for detecting the intake air amount of the engine;
The supercharging pressure control means performs the supercharging control by controlling the supercharging pressure adjusting device so that the intake air amount of the intake air amount detecting means becomes a predetermined target intake air amount. Engine control system. An exhaust turbocharger having a compressor provided in the intake passage of the engine and a turbine provided in the exhaust passage;
A supercharging pressure adjusting device for adjusting the supercharging pressure of the exhaust turbo supercharging device;
A supercharging pressure detecting means arranged in the intake passage for detecting a supercharging pressure of the exhaust turbocharger;
An exhaust pressure detecting means disposed in the exhaust passage for detecting the exhaust pressure of the engine;
A supercharging control for controlling the supercharging pressure adjusting device to set the supercharging pressure of the supercharging pressure detecting means to a predetermined target supercharging pressure; and a supercharging pressure and an exhaust pressure detecting means of the supercharging pressure detecting means. A supercharging pressure control means for performing exhaust control for determining the actual pumping loss of the engine from the exhaust pressure and controlling the supercharging pressure adjusting device so that the actual pumping loss becomes a predetermined target pumping loss;
An allowable upper limit calculating means for obtaining an allowable upper limit of pumping loss from the operating state of the engine,
The supercharging pressure control means includes
When the actual pumping loss is equal to or greater than a predetermined low exhaust pressure pumping loss and less than the allowable upper limit value calculated by the allowable upper limit value calculating means,
Calculating a supercharging control value based on the supercharging control and an exhaust control value based on the exhaust control, and controlling the supercharging pressure adjusting device with an intermediate value between the supercharging control value and the exhaust control value. An engine control system characterized by

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