JP2016173056A - Control device for engine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress occurrence of surge noise by highly accurately estimating the occurrence of the surge noise.SOLUTION: A control device for an engine system 100 having an engine 108 and a supercharger 138 includes: a driving state identification section 188 for identifying a driving state of a vehicle mounted with the engine system; a first surge determination section 190 for determining whether or not a first surge condition that is an occurrence condition of surge noise is satisfied on the basis of the identified driving state of the vehicle and a driving state of the engine; a second surge determination section 192 for determining whether or not a second surge condition that is an occurrence condition of surge noise is satisfied on the basis of a flow rate of suction air passing through the compressor 138a and a pressure ratio between an inlet and an outlet of the compressor; and a variable nozzle control section 184 for controlling an opening of a variable nozzle 138c to an opening direction on the basis of the driving state of the vehicle and the driving state of the engine when the first surge condition and the second surge condition are satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an engine system that suppresses the generation of a surge noise in an engine system including a supercharger (turbocharger).

  Conventionally, by adopting a supercharger in an engine system, the fluidity of intake air is improved, and acceleration performance and combustion efficiency (fuel consumption) are improved. In addition, by providing a variable nozzle that changes the exhaust gas flow passage area in the exhaust gas flow passage of the turbine in the turbocharger, a high supercharging pressure can be realized even when the flow rate of the exhaust gas is small. Can do.

  By the way, if the accelerator pedal is loosened suddenly during supercharging operation, a surge noise may be generated. As shown in Patent Documents 1 to 7, a technique for performing processing for suppressing the occurrence of surge noise is disclosed for the problem of occurrence of such surge noise.

JP 2011-256743 A JP 2009-156197 A JP 2009-281144 A JP 2008-095557 A JP 2009-114991 A JP 2001-342840 A International Publication No. 2011/007455

  As described above, various technologies for suppressing the generation of surge noise have been studied, but the generation condition of the surge noise changes depending on the vehicle operating state and the engine operating state. It is difficult to estimate rigorously. Therefore, it is conceivable that the start determination of the process for suppressing the generation of the surge noise is set loosely (a margin is provided) to surely suppress the generation of the surge noise. In this way, it is possible to avoid a situation in which processing for suppressing the occurrence of a surge noise is not performed in spite of a situation where a surge noise is actually generated.

  However, by setting the margin in this way, processing for excessively suppressing the generation of surge noise is executed even in a situation where surge noise does not occur, and the flow rate of intake air passing through the compressor becomes unnecessarily large. The temperature of the catalyst arranged in the exhaust pipe is lowered. In this case, there may arise a problem that the reproduction function of DPF (Diesel Particulate Filter) is not sufficiently exhibited.

  In view of the above problems, the present invention has an object to provide a control device for an engine system that can effectively suppress the generation of surge noise by estimating the generation of surge noise with high accuracy. It is said.

  In order to solve the above problems, an engine having a combustion chamber, a turbine that is communicated with the combustion chamber and rotated by exhaust gas discharged from the combustion chamber, and rotates integrally with the turbine to pressurize intake air and send it to the combustion chamber. And a turbocharger having a variable nozzle that is provided in an exhaust gas flow path of the turbine and changes a flow area of the exhaust gas. An operating state specifying unit that specifies a state, and a first surge determining unit that determines whether or not a first surge condition that is a condition for generating a surge noise is satisfied based on the specified vehicle operating state and engine operating state And a second surge condition that is a condition for generating a surge noise based on the flow rate of the intake air passing through the compressor and the pressure ratio between the inlet and outlet of the compressor A second nozzle for determining whether or not, and a variable nozzle that controls the opening of the variable nozzle in the opening direction based on the vehicle operating state and the engine operating state when the first surge condition and the second surge condition are satisfied And a control unit.

  The first surge determination unit may compare a parameter indicating the operating state of the engine with a predetermined value to determine whether or not the first surge condition is satisfied, and may change the predetermined value based on the operating state of the vehicle.

  The driving state of the vehicle may include at least a shift change state and a coast state.

  The driving state of the vehicle may further include an idling state of the engine.

  The parameters indicating the operating state of the engine include the pressure of the intake manifold communicated with the combustion chamber, and the fuel injection amount change rate of the injector that injects fuel into the combustion chamber. The first surge determination unit determines the pressure of the intake manifold. May be determined to satisfy the first surge condition when the fuel injection amount change rate of the injector is greater than or equal to a predetermined change rate.

  The predetermined pressure may be changed according to the engine speed.

  The predetermined rate of change may be changed by the pressure of the intake manifold.

  The second surge determination unit determines the second surge condition when the position on the compressor map specified by the compressor flow rate and the compressor inlet / outlet pressure ratio is included in a surge region having a predetermined surge line as a boundary. You may determine with satisfy | filling.

  When the variable nozzle control unit does not satisfy the first surge condition and the second surge condition after satisfying the first surge condition and the second surge condition, the variable nozzle control unit performs the first surge condition and the second It may not be determined whether or not the surge condition is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of surge noise can be effectively suppressed by estimating generation | occurrence | production of surge noise with high precision.

It is the figure which showed the schematic structure of the engine system. It is explanatory drawing for demonstrating the surge area | region in a compressor map. It is explanatory drawing for demonstrating an intake manifold threshold value and a fuel threshold value. It is explanatory drawing for demonstrating the opening degree of a variable nozzle when it determines with satisfy | filling 1st surge conditions and 2nd surge conditions. It is explanatory drawing for demonstrating the opening degree of a throttle valve. It is a compressor map for demonstrating the effect of an engine system. It is a timing chart for demonstrating the effect of an engine system. It is a timing chart of surge judgment. It is the flowchart which showed the flow of the process of the surge sound suppression method.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Engine system 100)
FIG. 1 is a diagram showing a schematic configuration of the engine system 100. Here, an in-cylinder direct injection four-cylinder diesel engine will be described as the engine 108, and the flow of fluid is indicated by white arrows. The engine 108 is mounted on, for example, a vehicle and supplies driving force to the vehicle. The engine 108 is provided with a cylinder block 110, a cylinder head 112 provided on the upper portion of the cylinder block 110, and a piston 116 supported by a connecting rod 114 so as to be slidable within the cylinder block 110. A space surrounded by the cylinder block 110, the cylinder head 112, and the upper surface of the piston 116 is formed as a combustion chamber 118.

  An intake manifold 120 and an exhaust manifold 122 are provided in the cylinder head 112 so as to communicate with the combustion chamber 118. Between the intake manifold 120 and the combustion chamber 118, the tip of the intake valve 124 is located. An intake valve cam 126 is in contact with the other end of the intake valve 124, and the intake valve cam 126 rotates to open and close between the intake manifold 120 and the combustion chamber 118. Further, the tip of the exhaust valve 128 is located between the exhaust manifold 122 and the combustion chamber 118. The exhaust valve 128 is in contact with the exhaust valve cam 130 at the other end, and opens and closes between the exhaust manifold 122 and the combustion chamber 118 when the exhaust valve cam 130 rotates.

  The cylinder head 112 is provided with an injector (fuel injection valve) 132 so that the tip is located in the combustion chamber 118, and the injector 132 injects fuel into the combustion chamber 118. In the combustion chamber 118, the fuel injected from the injector 132 comes into contact with the intake air compressed and heated by the piston 116, so that spontaneous combustion occurs, and the piston 116 reciprocates due to the explosion pressure. Such reciprocating motion of the piston 116 is changed to rotational motion of the crankshaft 134 through the connecting rod 114.

  The intake air compressed by the compressor 138a of the supercharger 138 through the air cleaner 136 is cooled by the intercooler 140, and then flows into the intake manifold 120 from the intake pipe 142 and is supplied to the combustion chamber 118 of the engine 108. Is done. The throttle valve 144 is provided in the intake pipe 142 and controls the flow rate of the intake air by adjusting the flow path width (opening degree) of the intake pipe 142.

  An exhaust pipe 146 communicates with the exhaust manifold 122. Exhaust gas flowing through the exhaust pipe 146 rotates a turbine 138b of a supercharger 138 connected to the exhaust pipe 146, and a catalyst in which a catalyst is accommodated. It is purified by unit 148 and discharged.

  In the supercharger 138, the compressor 138a rotates integrally with the turbine 138b, the intake air is pressurized by the rotation of the compressor 138a, and the supercharged air is sent to the combustion chamber 118 of the engine 108. With such a supercharger 138, the fluidity of the intake air can be increased, and acceleration performance and combustion efficiency (fuel consumption) can be improved.

  In the present embodiment, a variable nozzle type turbo (VNT) is adopted as the supercharger 138, and the variable nozzle 138c provided in the exhaust gas flow path of the housing of the turbine 138b is used as an exhaust gas. The supercharging pressure is adjusted by changing the flow passage area (opening).

  An HPPEG (High Pressure EGR) flow path 150 connects the upstream of the turbine 138 b in the exhaust pipe 146 and the downstream of the throttle valve 144 in the intake pipe 142. The HPEGR flow path 150 is provided with an HPEGR cooler 152, and the exhaust gas cooled by the HPEGR cooler 152 returns to the combustion chamber 118 together with the intake air cooled by the intercooler 140. The HPEGR valve 154 is provided in the HPEGR channel 150 and controls the flow rate of the exhaust gas to be circulated to the combustion chamber 118 by adjusting the channel width of the HPEGR channel 150. Thus, by circulating the exhaust gas to the combustion chamber 118, it is possible to reduce the oxygen concentration, reduce the combustion temperature of the fuel, and suppress the production of NOx (nitrogen oxide) and the like.

  An LPEGR (Low Pressure EGR) flow path 156 communicates the downstream of the catalyst unit 148 in the exhaust pipe 146 and the downstream of the air cleaner 136 in the intake pipe 142. The LPEGR flow path 156 is provided with an LPEGR cooler 158, and the exhaust gas cooled by the LPEGR cooler 158 returns to the combustion chamber 118 together with the intake air that has passed through the air cleaner 136. The LPEGR valve 160 is provided in the LPEGR channel 156 and controls the flow rate of the exhaust gas to be circulated to the combustion chamber 118 by adjusting the channel width of the LPEGR channel 156. In this way, like the HPPEG flow path 150, the exhaust gas is circulated to the combustion chamber 118, whereby the oxygen concentration can be reduced, the combustion temperature of the fuel can be reduced, and the production of NOx and the like can be suppressed. In addition, the LPEGR channel 156 can circulate a large amount of exhaust gas at a low temperature, although there may be a response delay compared to the HPEGR channel 150.

  The intake manifold pressure sensor 162 detects the pressure of the intake manifold 120 (hereinafter simply referred to as “intake manifold pressure”). The crank angle sensor 164 detects the crank angle of the crankshaft 134. The airflow sensor 166 detects the flow rate of the intake air that has passed through the air cleaner 136. The shift position sensor 168 detects the shift position (forward position (D range), reverse position (R range), neutral position (N range), parking position (P range)) of the transmission to which the output of the engine 108 is transmitted. . The vehicle speed sensor 170 detects the speed of the vehicle. The drive shaft rotational speed sensor 172 detects the rotational speed of the drive shaft of the vehicle. The atmospheric pressure sensor 174 detects the atmospheric pressure outside the vehicle. Each of these sensors is connected to an ECU (Engine Control Unit) 176, and outputs a signal indicating the detected value to the ECU 176.

  The ECU 176 is a microcomputer including a central processing unit (CPU), a ROM in which programs are stored, a RAM as a work area, and the like, and functions as a control device that performs overall control of the engine system 100. The ECU 176 is connected to an injector 132, a variable nozzle 138c, and a throttle valve 144, to which a command signal from the ECU 176 is input. The ECU 176 also functions as a signal acquisition unit 180, a fuel control unit 182, a variable nozzle control unit 184, a throttle control unit 186, an operation state specifying unit 188, a first surge determination unit 190, and a second surge determination unit 192. Each functional unit will be described in detail below.

  The signal acquisition unit 180 acquires signals indicating detection values detected by the intake manifold pressure sensor 162, the crank angle sensor 164, the airflow sensor 166, the shift position sensor 168, the vehicle speed sensor 170, the drive shaft rotational speed sensor 172, and the atmospheric pressure sensor 174. To do. Further, the signal acquisition unit 180 derives the rotational speed of the engine 108 based on the signal indicating the crank angle acquired from the crank angle sensor 164.

  The fuel control unit 182 refers to the fuel injection timing map and responds to the accelerator opening (the amount of depression of the accelerator pedal) at a predetermined phase corresponding to the crank angle, for example, a predetermined angle after the bottom dead center of the compression stroke. Inject fuel for a certain amount (period). The fuel control unit 182 derives the change rate (fuel injection amount change rate) based on the difference in the fuel injection amount per unit time. Along with the fuel injection, the intake valve 124 opens after the top dead center of the piston 116 and closes after the bottom dead center in the intake stroke according to the rotation of the intake valve cam 126. The exhaust valve 128 opens after the bottom dead center of the piston 116 and closes after the top dead center in the exhaust stroke according to the rotation of the exhaust valve cam 130.

  The variable nozzle control unit 184 controls the flow rate of the exhaust gas introduced into the turbine wheel by adjusting the opening of the variable nozzle 138c and changing the flow passage area of the exhaust gas. With the configuration of the variable nozzle 138c and the variable nozzle control unit 184, the rotational speeds of the turbine 138b and the compressor 138a can be increased regardless of the flow rate of the exhaust gas in the exhaust pipe 146. As a result, the pressure at the outlet of the compressor 138a, that is, In addition, the pressure (intake pressure) of the intake air introduced into the combustion chamber 118 can be increased.

  The throttle control unit 186 adjusts the opening of the throttle valve 144 and controls the flow rate of intake air. In a diesel engine, since adjustment of the air-fuel ratio is unnecessary, the throttle control unit 186 normally maintains the throttle valve 144 in the open state. However, in order to regenerate the DPF by burning particulate matter or to increase the flow rate of the HPEGR flow path 150 immediately after the engine 108 is started to reduce NOx, at such timing, the throttle control unit 186 performs the discharge. In order to increase the temperature of the gas, the throttle valve 144 is throttled to an opening based on the rotational speed of the engine 108.

  FIG. 2 is an explanatory diagram for explaining a surge region in the compressor map. Here, the flow rate of the intake air passing through the compressor 138a on the horizontal axis (hereinafter simply referred to as “the flow rate of the compressor 138a”) and the pressure ratio between the inlet and outlet of the compressor 138a (hereinafter simply referred to as the “pressure ratio of the compressor 138a”) on the vertical axis. ”). As described above, in the engine system 100, the pressure at the outlet of the compressor 138a (pressure ratio between the inlet and outlet) can be reduced by narrowing the variable nozzle 138c even when the exhaust gas flow rate in the exhaust pipe 146 is low. Can be increased. However, when the accelerator opening is loosened while the variable nozzle 138c is being throttled, the flow rate of the intake air passing through the compressor 138a is significantly high when the pressure ratio of the compressor 138a is high, as shown by the solid arrows in FIG. It falls and enters a surge region (shown by hatching in FIG. 2) on the compressor map with the surge line as a boundary. That is, the problem of surge noise is likely to occur as a trade-off between maintaining the acceleration performance and combustion efficiency by narrowing the variable nozzle 138c.

  Further, as described above, when the DPF is regenerated or when the engine 108 is started, the throttle valve 144 may be throttled, and the flow rate of the intake air passing through the compressor 138a becomes lower. Under such circumstances, it is easy to enter the surge region on the compressor map (exceeding the surge line), and it is difficult to escape from the surge region.

  Here, it is recognized that the position on the compressor map specified by the flow rate of the compressor 138a and the pressure ratio of the compressor 138a is likely to be included in the surge region shown in FIG. It is conceivable to perform processing for suppressing the occurrence of surge noise. However, since the generation condition of the surge noise actually changes depending on the driving state of the vehicle and the driving state of the engine, it is difficult to strictly estimate the generation of the surge noise. Therefore, it is conceivable that the start determination of the process for suppressing the generation of the surge noise is set loosely (a margin is provided) to surely suppress the generation of the surge noise. In this way, it is possible to avoid a situation in which processing for suppressing the occurrence of a surge noise is not performed in spite of a situation where a surge noise is actually generated. However, by setting in this way, a process for suppressing the generation of excessive surge noise is performed even in a situation where no surge noise occurs, and the flow rate of intake air passing through the compressor becomes unnecessarily large, and the exhaust pipe As a result, the temperature of the catalyst disposed in the catalyst is lowered. As a result, there may arise a problem that the regeneration function of the DPF is not sufficiently exhibited.

  Therefore, in this embodiment, (1) the current driving state of the vehicle is specified, the driving state of the vehicle (hereinafter simply referred to as “vehicle driving state”) and the operating state of the engine 108 (hereinafter simply referred to as “engine operating state”). Based on the flow rate of the compressor 138a and the pressure ratio of the compressor 138a. (2) Based on the flow rate of the compressor 138a and the pressure ratio of the compressor 138a If it is determined that the possibility of surge noise is high (whether or not the second surge condition is satisfied) and it is determined that the possibility of surge noise is high in any case, Processing to suppress the occurrence is performed. In this way, it is possible to estimate the occurrence of surge noise with high accuracy and suppress the occurrence of surge noise while improving acceleration performance and combustion efficiency by the variable nozzle 138c of the supercharger 138 in particular. Hereinafter, the determination of the first surge condition and the second surge condition, which are the conditions for generating the surge noise, and the processing for suppressing the subsequent occurrence of the surge noise will be described in detail.

(Determination of the first surge condition)
The driving state specifying unit 188 specifies the current vehicle driving state among a plurality of different vehicle driving states. Here, as a plurality of vehicle driving states, a racing state, a shift change state, and a coast state satisfying the corresponding vehicle driving conditions (racing conditions, shift change conditions, coast conditions, non-lockup drive shaft connection conditions) In addition, four vehicle operating states in the non-lock-up drive shaft connection state are included.

  The racing state corresponds to a so-called idling of the engine 108, and for example, satisfies the racing condition that the shift position of the transmission is at the neutral position and the vehicle is stopped (vehicle speed≈0). Say state. The driving state specifying unit 188 determines whether or not the vehicle driving state is a racing state based on the outputs of the shift position sensor 168 and the vehicle speed sensor 170.

  Further, the shift change state is a state in which the shift position is changed. For example, the shift change condition satisfies the shift change condition that the shift position of the transmission is in the neutral position and the vehicle is traveling (vehicle speed ≠ 0). Say that state. The driving state specifying unit 188 determines whether or not the vehicle driving state is the shift change state based on the outputs of the shift position sensor 168 and the vehicle speed sensor 170.

  The coast state corresponds to so-called inertia traveling. For example, if the vehicle is an AT (Automatic Transmission) vehicle including a CVT (Continuously Variable Transmission) or the like, the lock-up clutch is locked up or the vehicle is MT In the case of a (Manual Transmission) vehicle, the vehicle satisfies a coasting condition that the transmission shift position is other than the neutral position (forward position, reverse position). The driving state specifying unit 188 determines whether or not the vehicle driving state is a coast state based on vehicle information (whether it is an AT car or an MT car) held by the ECU 176 and the output of the shift position sensor 168. judge.

  The non-lock-up drive shaft connection state assumes a so-called stall state (state where the engine speed is increased by stepping on the accelerator while stepping on the brake on an AT vehicle) Is an AT vehicle, and the lockup clutch is not locked up, and the non-lockup drive shaft connection condition such that the transmission shift position is located at a position other than the neutral position is satisfied. The driving state specifying unit 188 includes vehicle information (whether the vehicle is an AT vehicle or an MT vehicle) held by the ECU 176, the output of the shift position sensor 168, and the engine speed derived by the signal acquisition unit 180. Based on the output of the drive shaft rotational speed sensor 172, it is determined whether or not the driving state of the vehicle is the non-lock-up drive shaft connection state. Whether or not the lockup clutch is locked up depends on the number of revolutions of the engine 108 and the number of revolutions of the drive shaft acquired by the drive shaft revolution number sensor 172 (the number of revolutions of the drive shaft downstream from the lockup clutch). Is determined by whether or not the difference is 0 or less than a predetermined number of revolutions. In addition to the above conditions, the vehicle speed acquired by the vehicle speed sensor 170 or the brake depression state may be taken into consideration in determining whether or not the drive shaft is in the non-lockup state. That is, in addition to the above-described conditions, it may be determined that the drive shaft is connected to the non-lock-up state when the vehicle speed is 0 and the brake is depressed.

  When the above-mentioned vehicle driving conditions (racing conditions, shift change conditions, coast conditions, non-lockup drive shaft connection conditions) are satisfied, the driving state specifying unit 188 determines that the current vehicle driving state is the vehicle driving condition. If it is determined that the vehicle is in the corresponding driving state, and if it is not satisfied, it is determined that the vehicle is in another driving state.

  Whether first surge determination unit 190 satisfies the first surge condition that is a condition for generating a surge sound (highly likely to occur) based on the vehicle operating state and engine operating state specified by driving state specifying unit 188 Judge whether or not. In the present embodiment, the parameters indicating the engine operating state include the intake manifold pressure indicating the load of the engine 108 and the fuel injection amount change rate indicating the degree of change in the accelerator operation (which becomes higher when the accelerator is suddenly released). . Accordingly, the first surge determination unit 190 compares the parameter indicating the driving state with a predetermined value, and specifically sets the intake manifold pressure and the fuel injection amount change rate to threshold values (intake manifold threshold value, fuel flow rate) corresponding to the respective vehicle driving states. The intake manifold pressure is equal to or greater than the intake manifold threshold (predetermined pressure), and the fuel injection amount change rate represented by an absolute value is the fuel threshold (predetermined change rate: more specifically, the fuel injection amount is If it is equal to or greater than a predetermined rate of change in a decreasing direction, it is determined that the first surge condition is satisfied.

  Here, the conditions for generating the surge noise vary for each vehicle operating state. Therefore, the intake manifold threshold and the fuel threshold are set to different values according to the vehicle operating state. In addition to this, the intake manifold threshold value is varied according to the engine speed depending on the vehicle operating state, and the fuel threshold value is varied according to the intake manifold pressure.

  FIG. 3 is an explanatory diagram for explaining the intake manifold threshold and the fuel threshold. 3A, the horizontal axis represents the engine speed, the vertical axis represents the intake manifold threshold value, and FIG. 3B, the horizontal axis represents the intake manifold pressure, and the vertical axis represents the fuel threshold value. The coast state and the non-lockup drive shaft connection state are indicated by a solid line, a broken line, a one-dot chain line, and a two-dot chain line, respectively.

  As shown in FIG. 3A, intake manifold thresholds are provided corresponding to the respective vehicle operating states. Among these, regarding the shift change state and the coast state, the intake manifold threshold is changed according to the rotational speed of the engine 108. The shift change state and coast state are running, and compared to the racing state that is assumed to be stopped and the drive shaft connected state when not locked up, the effect on the exhaust gas is controlled by a process that suppresses the generation of surge noise described later. Is likely to occur. In addition, road noise and the like are generated during traveling, so that it is difficult to hear a surge sound compared to when the vehicle is stopped. Therefore, as shown in FIG. 3A, the intake manifold threshold value in the shift change state and the coast state is set to be higher than the intake manifold threshold value in the racing state or the non-lockup drive shaft connection state, thereby It was made difficult to satisfy the conditions, and the exhaust gas was not affected. Further, the coast state is less likely to enter the surge region because the decrease in the compressor passage flow rate per unit time when the accelerator is loosened is slower than in the shift change state. Therefore, the intake manifold threshold in the coast state is set higher than that in the shift change state.

  Further, as shown in FIG. 3B, a fuel threshold value is provided corresponding to each vehicle operating state, and the fuel threshold value for each vehicle operating state is changed according to the intake manifold pressure. Specifically, the fuel threshold value in the shift change state (especially the shift change state at the time of acceleration) where the occurrence of the surge noise is most concerned is made smaller than the fuel threshold value in other vehicle operating states, and the first surge condition is easily satisfied. I did it.

  Therefore, the first surge determination unit 190 extracts the intake manifold threshold from FIG. 3A based on the current vehicle operating state and the engine speed, and based on the current vehicle operating state and the intake manifold pressure, FIG. If the fuel threshold is extracted from (b), the current intake manifold pressure is equal to or greater than the extracted intake manifold threshold, and the current fuel injection amount change rate is equal to or greater than the extracted fuel threshold, the first surge condition is satisfied. Is determined. With this configuration, it is possible to appropriately determine whether or not the first surge condition is satisfied while reducing the influence on other performance such as exhaust gas.

  A hysteresis characteristic can also be provided in determining whether or not the first surge condition is satisfied. For example, the first surge determination unit 190 determines that the first surge condition is satisfied when the intake manifold pressure is equal to or higher than the intake manifold threshold and the fuel injection amount change rate is equal to or higher than the fuel threshold, and the intake manifold pressure or the fuel injection amount change rate is determined. Is lower than the respective threshold values, it is determined that the first surge condition is no longer satisfied. However, even if the intake manifold pressure is less than the intake manifold threshold or the fuel injection amount change rate is less than the fuel threshold, it is not immediately determined that the first surge condition is not satisfied, and the intake manifold pressure is smaller than the intake manifold threshold. It is determined that the first surge condition is not satisfied for the first time when the fuel injection amount change rate becomes a predetermined threshold smaller than the fuel threshold. In this way, chattering in the vicinity of the intake manifold threshold and the fuel threshold can be prevented.

(Determination of second surge condition)
The second surge determination unit 192 refers to the compressor map shown in FIG. 2 and determines whether or not a second surge condition that is a condition for generating a surge noise is satisfied based on the flow rate of the compressor 138a and the pressure ratio of the compressor 138a. That is, it is determined whether or not the position on the compressor map specified by the flow rate of the compressor 138a and the pressure ratio of the compressor 138a is included in the surge region having the predetermined surge line in FIG.

  First, the second surge determination unit 192 derives the flow rate of the compressor 138a and the pressure ratio of the compressor 138a. Among these, the flow rate of the compressor 138a is derived by adding the flow rate of the LPEGR flow path 156 to the total intake air amount detected by the airflow sensor 166. Here, the flow rate of the LPEGR channel 156 is derived as follows. That is, the flow rate passing through the intake manifold 120 is determined from the structure of the intake manifold 120 and the intake efficiency, and when the total intake air amount detected by the airflow sensor 166 is subtracted from the flow rate passing through the intake manifold 120, the HPPEG flow path 150 and The total flow rate of the LPEGR channel 156 is obtained. The flow rate of the LPEGR channel 156 can be derived by multiplying the total flow rate of the HPEGR channel 150 and the LPEGR channel 156 by the flow rate ratio of the LPEGR channel 156.

  Further, the pressure ratio of the compressor 138a is obtained by dividing the pressure at the outlet of the compressor 138a by the pressure at the inlet of the compressor 138a. The pressure at the outlet of the compressor 138a is a value obtained by adding the pressure loss of the throttle valve 144 to the intake manifold pressure detected by the intake manifold pressure sensor 162. Here, the pressure loss of the throttle valve 144 is derived from a map prepared in advance using the opening degree of the throttle valve 144 and the flow rate of the compressor 138a as parameters. The pressure at the inlet of the compressor 138a is a value obtained by adding the pressure loss of the air cleaner 136 to the atmospheric pressure detected by the atmospheric pressure sensor 174. Here, the pressure loss of the air cleaner 136 is derived from a map prepared in advance using the total amount of intake air detected by the airflow sensor 166 as a parameter.

  Thus, in addition to determining whether or not the first surge determination unit 190 is likely to generate a surge noise based on the vehicle operation state and the engine operation state, the second surge determination unit 192 By determining whether or not it is within the surge region in FIG. 2, it is possible to estimate the occurrence of surge noise with high accuracy.

  When the variable nozzle control unit 184 determines that the first surge determination unit 190 satisfies the first surge condition and the second surge determination unit 192 determines that the second surge condition is satisfied, the current vehicle operating state and the engine Based on the rotational speed of 108, the opening degree of the variable nozzle 138c is controlled in the opening direction (direction in which the opening degree is increased).

  As described above, the variable nozzle control unit 184 normally throttles the variable nozzle 138c in order to increase the pressure at the outlet of the compressor 138a (in order to increase acceleration performance). Here, when the first surge determination unit 190 satisfies the first surge condition and the second surge determination unit 192 determines that the second surge condition is satisfied, the variable nozzle control unit 184 avoids the generation of the surge noise. Therefore, the opening degree of the variable nozzle 138c is increased.

  FIG. 4 is an explanatory diagram for explaining the opening of the variable nozzle 138c when it is determined that the first surge condition and the second surge condition are satisfied. Specifically, for example, when the current vehicle driving state is a shift change state or a coast state, as shown by a broken line in FIG. As indicated by the white arrow in (a), the opening degree of the variable nozzle 138c is increased from the closed state. Further, when the current vehicle driving state is a racing state or a non-lock-up driving shaft connection state, as shown by a broken line in FIG. b) As indicated by the white arrow in the figure, the opening degree of the variable nozzle 138c is increased from the closed state. Further, the opening degree of the variable nozzle 138c is set higher in the racing state or in the non-lockup drive shaft connection state than in the shift change state and the coast state. This is because, in the shift change state and the coast state during traveling, in order to suppress a decrease in drivability, the opening of the variable nozzle 138c is limited, whereas the racing state that is assumed to be stopped or This is because there is no need to worry about a decrease in drivability in the non-lock-up drive shaft connection state, and thus there is no limit on the opening of the variable nozzle 138c (full opening).

  Further, as shown in FIGS. 4A and 4B, the opening degree of the variable nozzle 138c is changed depending on the external environment, for example, in the normal environment and in the high altitude environment where the air density and the air temperature are lower than the normal environment. Set to a different value. Specifically, the opening degree of the variable nozzle 138c in the high altitude environment is made larger than that in the normal environment. This is because the air density is low and the turbine speed is likely to increase at high altitudes, and the air density is low and the in-cylinder pressure is likely to increase at low temperatures. Whether or not the environment is a high altitude environment is determined by the ECU 176 based on the output of the atmospheric pressure sensor 174, for example. Whether or not the environment is a high altitude environment is determined by the ECU 176 based on, for example, the output of an intake air temperature sensor (not shown).

  Further, the variable nozzle control unit 184 determines that any one of the surge conditions is not satisfied due to a decrease in the intake manifold pressure or the fuel injection amount change rate from the state where the first surge condition and the second surge condition are determined to be satisfied. In this case, the opening degree of the variable nozzle 138c is controlled in the closing direction to return to the opening degree immediately before determining that the first surge condition and the second surge condition are satisfied. At this time, the opening degree may not be changed at a time, but may be gradually changed by a gradually decreasing curve with a predetermined change rate (inclination). A linear or multi-order curve can be used as the gradual decrease curve. With such a configuration, it is possible to smoothly shift to normal control, and it is possible to effectively suppress the generation of surge noise due to a sudden change in the opening of the variable nozzle 138c.

  When the first surge condition and the second surge condition are satisfied, the throttle control unit 186 opens the throttle valve 144 that adjusts the flow path width of the intake pipe 142 communicated with the combustion chamber 118 based on the rotational speed of the engine 108. Control the degree in the opening direction.

  As described above, the throttle control unit 186 sets the throttle valve 144 to the rotational speed of the engine 108 in order to regenerate the DPF by burning the particulate matter or to increase the flow rate of the HPEGR flow path 150 to reduce NOx. The opening may be adjusted depending on the situation. In such a situation, if the first surge determination unit 190 satisfies the first surge condition and the second surge determination unit 192 determines that the second surge condition is satisfied, the throttle is set to avoid the generation of the surge noise. The valve 144 is controlled in the opening direction.

  FIG. 5 is an explanatory diagram for explaining the opening degree of the throttle valve 144. Specifically, for example, even if the throttle valve 144 is relatively closed as indicated by the broken line in FIG. 5 due to regeneration of the DPF or increase in EGR, the first surge condition and the second surge condition If it is determined that the condition is satisfied, the opening degree of the throttle valve 144 is increased based on the number of revolutions of the engine 108 as shown by the white arrow in FIG. At this time, similarly to FIG. 4, for example, the opening degree of the throttle valve 144 is set to a different value in the normal environment and the high altitude environment depending on the external environment. Specifically, the opening degree of the throttle valve 144 in the high altitude environment is made larger than that in the normal environment. This takes into account the low air density at high altitudes.

  Further, the throttle control unit 186 has determined that the first surge condition and the second surge condition have been satisfied, and has no longer satisfied any of the surge conditions due to a decrease in the intake manifold pressure or the fuel injection amount change rate. In this case, the opening degree of the throttle valve 144 is controlled in the closing direction to return to the opening degree immediately before it is determined that the first surge condition and the second surge condition are satisfied. At this time, like the variable nozzle 138c, the throttle valve 144 may not be changed at a time, but may be gradually changed according to a gradually decreasing curve with a predetermined change rate (inclination).

  As described above, according to the engine system 100 of the present embodiment, it is possible to estimate the occurrence of surge noise with high accuracy and to effectively suppress the occurrence of surge noise. The specific effect will be described below.

  FIG. 6 is a compressor map for explaining the effect of the engine system 100, and FIG. 7 is a timing chart for explaining the effect of the engine system 100. The compressor map shows the flow rate of the compressor 138a on the horizontal axis and the pressure ratio of the compressor 138a on the vertical axis.

  For example, in the engine system 100, when the accelerator opening is loosened with the variable nozzle 138c being throttled, as shown by the broken arrow in FIG. 6, the suction passing through the compressor 138a with the pressure ratio of the compressor 138a being high. The air flow rate drops significantly and enters the surge area on the compressor map. In this case, since the second surge condition is satisfied, the variable nozzle controller 184 opens the opening of the variable nozzle 138c in the opening direction (in the direction of increasing the opening) based on the current vehicle operating state and the engine speed. The throttle control unit 186 controls the opening degree of the throttle valve 144 in the opening direction based on the rotational speed of the engine 108.

  However, in the second surge condition alone, the generation of surge noise is estimated by a surge line having a margin with respect to the actual surge line that changes depending on the driving state of the vehicle and the driving state of the engine 108. As indicated by an alternate long and short dash line in FIG. 6, over-protection is caused by starting the process of suppressing the generation of surge noise at an early stage. However, in this embodiment, since the first surge condition is used in addition to the second surge condition, the actual condition changes depending on the driving state of the vehicle and the driving state of the engine 108 as shown by the solid line arrow in FIG. The process of suppressing the generation of surge noise can be started appropriately after the surge line is approached.

  Thus, by determining whether or not both the first surge condition and the second surge condition are satisfied, conventionally, as shown by the broken line in FIG. In the present embodiment, the process for suppressing surges can be started at an appropriate timing as indicated by the solid line in FIG. 7A. Therefore, as shown in FIG. 7B, the timing for controlling the opening degree of the throttle valve 144 in the opening direction is also performed at an appropriate timing, and as shown by the white arrow in FIG. It becomes possible to suppress the temperature drop of the catalyst.

(Exclusion condition)
By the way, as described above, the second surge determination unit 192 derives the pressure ratio of the compressor 138a to determine the second surge condition, and derives the pressure at the outlet of the compressor 138a to derive the pressure ratio of the compressor 138a. Derived. The pressure at the outlet of the compressor 138a is a value obtained by adding the pressure loss of the throttle valve 144 to the intake manifold pressure detected by the intake manifold pressure sensor 162. That is, the second surge determination unit 192 determines the second surge condition based on the intake manifold pressure.

  FIG. 8 is a timing chart of surge determination. When either the first surge condition or the second surge condition is not satisfied at time t in FIG. 8A, the throttle control unit 186 sets the engine speed to the rotational speed of the engine 108 as shown in FIG. 8B. Based on this, the opening degree of the throttle valve 144 is controlled in the closing direction. As the opening of the throttle valve 144 decreases, the intake manifold pressure also decreases as shown in FIG. However, actually, as shown in FIG. 8C, there is a delay with respect to the change in the opening degree of the throttle valve 144. Therefore, the intake manifold pressure is derived higher than the actual decrease in the opening of the throttle valve 144. As described above, when it is determined that the intake manifold pressure is higher than the original value, the pressure at the outlet of the compressor 138a increases accordingly, and as a result, the pressure ratio of the compressor 138a increases.

  As described above, when the pressure ratio of the compressor 138a suddenly increases, it can be determined that a surge noise is generated in a state that should not be positioned in the surge region, as can be understood with reference to FIG. In this case, the throttle control unit 186 performs unnecessary opening / closing of the throttle valve 144.

  Therefore, in the present embodiment, if the variable nozzle control unit 184 does not satisfy the first surge condition and the second surge condition after satisfying the first surge condition and the second surge condition, a predetermined time immediately after the first surge condition and the second surge condition are not satisfied. In (for example, 2 seconds), it is not determined whether the first surge condition and the second surge condition are satisfied. By doing so, it is possible to avoid an event that erroneously determines that a surge noise occurs in a state where it should not be estimated that a surge noise will occur.

(Surge noise suppression method)
Below, the specific process of the surge noise suppression method using the engine system 100 is demonstrated.

  FIG. 9 is a flowchart showing a processing flow of the surge noise suppression method. Here, the surge noise suppression method is repeatedly performed by an interrupt process that occurs at predetermined time intervals.

  First, the signal acquisition unit 180 acquires signals indicating detection values detected by the intake manifold pressure sensor 162, the crank angle sensor 164, the shift position sensor 168, the vehicle speed sensor 170, and the drive shaft rotational speed sensor 172, and the rotational speed of the engine 108. Is derived (S200). Subsequently, the fuel control unit 182 derives a fuel injection amount change rate based on the injected fuel (S202). Next, the driving state specifying unit 188 determines whether or not any of a plurality of vehicle driving conditions (racing conditions, shift change conditions, coast conditions, non-lockup driving shaft connection conditions) is satisfied, and the vehicle driving conditions are determined. When satisfied, the vehicle driving state (racing state, shift change state, coast state, non-lockup drive shaft connection state) corresponding to the vehicle driving condition is specified as the current vehicle driving state (S204).

  The first surge determination unit 190 determines whether or not a predetermined vehicle driving state (racing state, shift change state, coast state, non-lockup drive shaft connection state) is specified as the vehicle driving state (S206). If the predetermined vehicle operation state is not specified, that is, if it is specified as another vehicle operation state (NO in S206), the surge noise suppression method is terminated. If the predetermined vehicle operating state is specified (YES in S206), first surge determination unit 190 is based on the specified vehicle operating state and engine operating state (intake manifold pressure, fuel injection amount change rate). Whether or not the first surge condition is satisfied is determined (S208).

  Here, if it is not determined that the first surge condition is satisfied (NO in S208), the surge noise suppression method is terminated. Further, if it is determined that the first surge condition is satisfied (YES in S208), the second surge determination unit 192 sets the second surge condition based on the flow rate of the compressor 138a and the pressure ratio of the compressor 138a. It is determined whether or not it is satisfied (S210).

  If it is not determined that the second surge condition is satisfied (NO in S210), the surge noise suppression method is terminated. Further, if it is determined that the second surge condition is satisfied (YES in S210), the variable nozzle control unit 184 determines whether or not the exclusion condition is satisfied, that is, the current state is the first surge condition and the second surge. It is determined whether it is within a predetermined time after any of the conditions is not satisfied (S212).

  If it is determined that the exclusion condition is satisfied (YES in S212), the surge noise suppression method is terminated. If it is determined that the exclusion condition is not satisfied (NO in S212), the variable nozzle control unit 184 controls the opening of the variable nozzle 138c in the opening direction based on the vehicle operating state and the engine speed. Then, the throttle control unit 186 controls the opening degree of the throttle valve 144 in the opening direction based on the rotational speed of the engine 108 (S216), and ends the surge noise suppression method.

  As described above, according to the engine system 100 of the present embodiment, by determining a plurality of conditions such as the first surge condition and the second surge condition while suppressing the influence on other performance such as exhaust gas and drivability. By estimating the generation of surge noise with high accuracy, it is possible to effectively suppress the generation of surge noise.

  Further, even when the opening of the variable nozzle 138c and the opening of the throttle valve 144 are increased in order to suppress the generation of surge noise, the opening is appropriately set based on the vehicle operating state and the engine speed. Therefore, it is possible to suppress the generation of surge noise, maintain acceleration performance and combustion efficiency, and maintain the exhaust gas temperature.

  Further, in the present embodiment, it is not necessary to separately add hardware such as a mechanism for releasing the pressure after passing through the compressor 138a, and the occurrence of surge noise is suppressed by using the existing variable nozzle 138c and the throttle valve 144. Therefore, it is possible to avoid an increase in cost required for a design change in addition to the weight, occupied volume, and cost of the mechanism.

  Also provided are a program that causes a computer to function as a control device of engine system 100, and a storage medium such as a flexible disk, magneto-optical disk, ROM, CD, DVD, or BD that can be read by a computer that records the program. Here, the program refers to data processing means described in an arbitrary language or description method.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the above-described embodiment, the diesel engine is described as an example of the engine 108. However, the present invention is not limited to this, and the degree of change in the accelerator operation is changed to the fuel injection amount change rate. Naturally, it can be applied to a gasoline engine by setting the opening change rate or the like.

  Note that each step of the surge noise suppression method of the present specification does not necessarily have to be processed in time series in the order described in the flowchart, and may include processing in parallel or a subroutine.

  INDUSTRIAL APPLICABILITY The present invention can be used for an engine system control device that suppresses the generation of surge noise in an engine system including a supercharger.

100 engine system 118 combustion chamber 120 intake manifold 132 injector 138 supercharger 138a compressor 138b turbine 138c variable nozzle 144 throttle valve 162 intake manifold pressure sensor 164 crank angle sensor 184 variable nozzle control unit 186 throttle control unit 188 operation state specifying unit 190 first Surge determination unit 192 Second surge determination unit

Claims (9)

An engine having a combustion chamber; a turbine communicating with the combustion chamber and rotating by exhaust gas discharged from the combustion chamber; A turbocharger having a variable nozzle that is provided in an exhaust gas flow path of the turbine and changes a flow area of the exhaust gas,
A driving state specifying unit for specifying a driving state of a vehicle on which the engine system is mounted;
A first surge determination unit that determines whether or not a first surge condition that is a condition for generating a surge noise is based on the identified driving state of the vehicle and the driving state of the engine;
A second surge determination unit that determines whether or not a second surge condition that is a condition for generating a surge noise is satisfied based on a flow rate of the intake air that passes through the compressor and a pressure ratio between an inlet and an outlet of the compressor;
When the first surge condition and the second surge condition are satisfied, a variable nozzle control unit that controls an opening degree of the variable nozzle in an opening direction based on an operation state of the vehicle and an operation state of the engine;
An engine system control device comprising:   The first surge determination unit compares a parameter indicating the operation state of the engine with a predetermined value to determine whether or not the first surge condition is satisfied, and changes the predetermined value based on the operation state of the vehicle. The engine system control device according to claim 1, wherein:   The engine system control device according to claim 1, wherein the driving state of the vehicle includes at least a shift change state and a coast state.   4. The engine system control device according to claim 3, wherein the driving state of the vehicle further includes an idling state of the engine. The parameters indicating the operating state of the engine include the pressure of the intake manifold communicated with the combustion chamber, and the fuel injection amount change rate of the injector that injects fuel into the combustion chamber,
The first surge determination unit determines that the first surge condition is satisfied when the pressure of the intake manifold is equal to or higher than a predetermined pressure and the fuel injection amount change rate of the injector is equal to or higher than a predetermined change rate. The engine system control device according to any one of claims 1 to 4, wherein:   The engine system control device according to claim 5, wherein the predetermined pressure is changed according to a rotational speed of the engine.   The engine system control device according to claim 5 or 6, wherein the predetermined change rate is changed by a pressure of the intake manifold.   The second surge determination unit is configured so that the position on the compressor map specified by the flow rate of the compressor and the pressure ratio between the inlet and the outlet of the compressor is included in a surge region having a predetermined surge line as a boundary. It determines with satisfy | filling 2nd surge conditions, The control apparatus of the engine system of any one of Claim 1 to 7 characterized by the above-mentioned.   The variable nozzle control unit, when the first surge condition and the second surge condition are not satisfied after the first surge condition and the second surge condition are satisfied, The engine system control device according to any one of claims 1 to 8, wherein it is not determined whether the first surge condition and the second surge condition are satisfied.

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