JP2017067002A - Control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure combustion stability and emission performance by properly limiting a rising speed of engine torque.SOLUTION: A control device of an engine has a basic target torque determination unit (61) for determining basic target torque on the basis of an operating state of a vehicle including an operation of an accelerator pedal, a torque reduction amount determination unit 63 for determining a torque reduction amount on the basis of an operating state of the vehicle excluding the operation of the accelerator pedal, a final target torque determination unit 65 for determining final target torque on the basis of the basic target torque and the torque reduction amount, a combustion state determination unit 71 for determining change of a combustion state in a cylinder according to whether a rising speed of the final target torque is over a predetermined determination threshold value or not when the torque reduction amount is lowered, and the final target torque is raised, and a final target torque correction unit 73 for correcting the final target torque so that the rising speed of the final target torque is limited to be the determination threshold value or less, when significant change of the combustion state is determined.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine control device, and more particularly, to an engine control device that controls an engine based on a driving state of a vehicle.

  2. Description of the Related Art Conventionally, devices that control the behavior of a vehicle in a safe direction when the behavior of the vehicle becomes unstable due to slip or the like (such as a skid prevention device) are known. Specifically, it is known to detect that understeer or oversteer behavior has occurred in the vehicle during cornering of the vehicle, and to impart appropriate deceleration to the wheels to suppress them. ing.

  On the other hand, unlike the above-described control for improving safety in a driving state where the behavior of the vehicle becomes unstable, a series of operations (braking, The vehicle motion control device adjusts the load applied to the front wheels, which are the steering wheels, by adjusting the deceleration at the cornering so that the steering incision, acceleration, steering return, etc. are natural and stable. Is known (see, for example, Patent Document 1).

  Furthermore, by reducing the driving force of the vehicle in accordance with the yaw rate related amount corresponding to the steering operation of the driver (for example, yaw acceleration), when the driver starts the steering operation, a deceleration is quickly generated in the vehicle. A vehicle behavior control device has been proposed in which a large load is quickly applied to a front wheel that is a steered wheel (see, for example, Patent Document 2). According to this vehicle behavior control device, the frictional force between the front wheel and the road surface is increased by rapidly applying a load to the front wheel at the start of the steering operation, and the cornering force of the front wheel is increased. The turning performance of the vehicle is improved, and the response to the steering operation is improved. As a result, the vehicle behavior as intended by the driver is realized.

JP 2011-88576 A JP 2014-166014 A

  Incidentally, there is a case where a request for suddenly increasing the engine torque is issued according to a change in the driving state of the vehicle. For example, as described above, after the engine torque is reduced so as to cause the vehicle to decelerate when the steering operation is started, a request for suddenly increasing the engine torque is issued in order to restore the engine torque. May be. In such a case, engine combustion stability, emission performance, and drivability may be reduced due to an excessive increase in engine torque. For example, in a diesel engine, a state in which oxygen is low occurs due to a delay in response of air in the cylinder, and soot may be discharged by injecting a large amount of fuel in this state. In addition, in a diesel engine, a state where the oxygen concentration is high is generated by suppressing the amount of EGR gas at a low torque before the engine torque is increased, and abnormal combustion occurs when a large amount of fuel is injected in this state. There is a fear.

  The present invention has been made to solve the above-described problems of the prior art, and can appropriately limit the rate of increase when the engine torque increases to ensure combustion stability and emission performance. An object of the present invention is to provide an engine control device.

In order to achieve the above object, the present invention is an engine control device that controls an engine based on a driving state of a vehicle, and determines a basic target torque based on the driving state of the vehicle including an operation of an accelerator pedal. A target torque determining means and a torque reduction amount determining means for determining a torque reduction amount for reducing the basic target torque based on the driving state of the vehicle other than the operation of the accelerator pedal. The final target torque is determined on the basis of the torque reduction amount determining means that increases the torque reduction amount when the vehicle driving state changes and then decreases the torque reduction amount toward 0, and the basic target torque and the torque reduction amount. A final target torque determining means for determining, and an engine control means for controlling the engine so as to output the final target torque. When the torque reduction amount is decreased by the reduction amount determining means and the final target torque determined by the final target torque determining means is increased, whether or not the rising speed of this final target torque exceeds a predetermined determination threshold Thus, the combustion state determining means for determining the change in the combustion state in the cylinder accompanying the increase in the final target torque, and the change in the combustion state by the combustion state determining means when the rising speed of the final target torque exceeds the determination threshold value. And a final target torque correcting means for correcting the final target torque so as to limit the rising speed of the final target torque to be equal to or less than a determination threshold when it is determined to be large.
In the present invention configured as described above, when the torque reduction amount is decreased by the torque reduction amount determining means and the final target torque determined by the final target torque determining means is increased, the increasing speed of the final target torque is When the determination threshold is exceeded, the combustion state determination means determines that the change in the combustion state in the cylinder accompanying the increase in the final target torque is large, and the final target torque correction means determines the increase speed of the final target torque as the determination threshold. The final target torque is corrected as follows. As a result, it is possible to appropriately limit the rate of increase when the engine torque increases, and to suppress deterioration in engine combustion stability, emission performance, and drivability.

In the present invention, preferably, the torque reduction amount determining means determines the torque reduction amount in accordance with a steering operation of the vehicle.
According to the present invention configured as described above, the time change of the torque reduction amount determined based on the steering operation can be reflected in the time change of the final target torque, thereby reducing the torque according to the driver's steering operation. By quickly adding speed to the vehicle and applying load to the front wheels, and quickly increasing the cornering force, the responsiveness to steering operation can be improved, ensuring the combustion stability and the driver's intended vehicle behavior The engine E can be controlled so as to accurately realize the above.

In the present invention, it is preferable that the determination threshold is a final target torque obtained by applying the torque reduction amount determined by the torque reduction amount determination means when the operation of turning back after turning the steering is performed at a predetermined steering speed or higher. It is set based on the rising speed.
By applying the determination threshold set in this way, it is possible to suppress a large change in the combustion state, which is likely to occur when the steering operation is performed as described above, and to improve the combustion stability and emission of the engine. Appropriate performance and drivability can be secured.

In the present invention, it is preferable that the determination threshold is an operation in which the accelerator pedal is depressed more than a predetermined opening degree while the torque reduction amount determined according to the steering operation by the torque reduction amount determination unit is applied to the final target torque. When it is performed, it is set based on the rising speed of the final target torque according to the accelerator pedal operation.
By applying the determination threshold set in this way, a large change in the combustion state, which is likely to occur when the accelerator pedal operation as described above is performed, is suppressed, and the combustion stability of the engine Emission performance and drivability can be secured appropriately.

In the present invention, it is preferable that the torque reduction amount determination means determines the torque reduction amount so that the torque reduction amount is increased and the increase rate of the increase amount is reduced as the steering speed of the vehicle increases.
According to the present invention configured as described above, when the steering of the vehicle is started and the steering speed of the vehicle starts to increase, the torque reduction amount can be quickly increased. The deceleration can be quickly applied to the vehicle, and a sufficient load can be quickly applied to the front wheels as the steering wheels. As a result, the frictional force between the front wheels, which are the steering wheels, and the road surface increase, and the cornering force of the front wheels increases, so that the turning ability of the vehicle at the beginning of the curve approach can be improved, and combustion stability is ensured. On the other hand, the responsiveness to the steering operation can be improved.

In the present invention, preferably, the basic target torque determining means determines the target acceleration of the vehicle based on the driving state of the vehicle including the operation of the accelerator pedal, and determines the basic target torque based on the target acceleration.
According to the present invention configured as described above, since the basic target torque is determined based on the target acceleration, it is possible to control the engine so as to accurately realize the acceleration intended by the driver while ensuring the combustion stability. it can.

In the present invention, preferably, the engine control device is a control device for a diesel engine including a fuel injection device that injects fuel into the cylinder, and the engine control means causes the diesel engine to output a final target torque. The fuel injection amount of the fuel injection device is controlled.
According to the present invention configured as described above, the fuel injection amount of the diesel engine is changed according to the final target torque reflecting the torque reduction amount, so that it is determined based on the driving state of the vehicle other than the operation of the accelerator pedal. The time change of the torque reduction amount can be accurately realized with high responsiveness, and the engine can be controlled to accurately realize the vehicle behavior intended by the driver.

  According to the engine control apparatus of the present invention, it is possible to appropriately limit the rate of increase when the engine torque increases, and to ensure combustion stability and emission performance.

1 is a schematic configuration diagram of an engine system to which an engine control device according to an embodiment of the present invention is applied. It is a block diagram which shows the electric constitution of the control apparatus of the engine by embodiment of this invention. It is a flowchart of the engine control process which the engine control apparatus by embodiment of this invention controls an engine. It is a flowchart of the torque reduction amount determination process in which the control apparatus of the engine by embodiment of this invention determines torque reduction amount. It is the map which showed the relationship between the additional deceleration and steering speed which the engine control apparatus by embodiment of this invention determines. FIG. 6A is a diagram showing a time change of parameters related to engine control by the engine control device when a vehicle equipped with the engine control device according to the embodiment of the present invention makes a turn. FIG. FIG. 6B is a plan view schematically showing the vehicle to be performed, FIG. 6B is a diagram showing a change in the steering angle of the vehicle turning right as shown in FIG. 6A, and FIG. 6C is FIG. FIG. 6D is a diagram showing a change in the steering speed of the vehicle that turns right as shown in FIG. 6B. FIG. 6D is a graph showing the additional deceleration determined based on the steering speed shown in FIG. 6 (e) is a diagram showing a change in torque reduction determined based on the additional deceleration shown in FIG. 6 (d), and FIG. 6 (f) is a smoothing by a torque change filter. FIG. 6G is a diagram showing changes in the basic target torque before and after conversion, and FIG. FIG. 6H is a diagram showing a change in the fuel injection amount determined based on the final target torque, and FIG. 6I is a diagram showing the change in the final target torque determined based on FIG. As shown in Fig. 4, the fuel injection amount was not controlled based on the change in the yaw rate (actual yaw rate) generated in the vehicle when the fuel injection amount was controlled and the torque reduction amount determined by the torque reduction amount determination unit It is a diagram which shows the change of the actual yaw rate in a case.

  Hereinafter, an engine control apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[System configuration]
First, an engine system to which an engine control apparatus according to an embodiment of the present invention is applied will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an engine system to which an engine control apparatus according to an embodiment of the present invention is applied.

  As shown in FIG. 1, the engine system 200 mainly includes an engine E as a diesel engine, an intake system IN that supplies intake air to the engine E, a fuel supply system FS that supplies fuel to the engine E, It has an exhaust system EX that exhausts exhaust gas from the engine E, sensors 96 to 110 that detect various states related to the engine system 200, and a PCM (Power-train Control Module) 60 that controls the engine system 200.

First, the intake system IN has an intake passage 1 through which intake air passes, and an air cleaner 3 that purifies air introduced from the outside in order from the upstream side, and intake air that passes through the intake passage 1. The compressor 5a of the turbocharger 5 that compresses and raises the intake pressure, the intake shutter valve 7 that adjusts the flow rate of the intake air that passes through, and the water-cooled intercooler that cools the intake air using the coolant that has passed through 8 and a surge tank 12 for temporarily storing intake air supplied to the engine E.
In the intake system IN, an air flow sensor 101 for detecting the intake air amount and an intake air temperature sensor 102 for detecting the intake air temperature are provided on the intake passage 1 immediately downstream of the air cleaner 3, and the turbocharger 5. The compressor 5a is provided with a turbo rotational speed sensor 103 for detecting the rotational speed (turbo rotational speed) of the compressor 5a. The intake shutter valve 7 has an intake shutter valve for detecting the opening degree of the intake shutter valve 7. A position sensor 105 is provided, and an intake air temperature sensor 106 for detecting the intake air temperature and an intake air pressure sensor 107 for detecting the intake air pressure are provided on the intake passage 1 immediately downstream of the intercooler 8. The intake manifold temperature sensor 108 is provided. These various sensors 101 to 108 provided in the intake system IN output detection signals S101 to S108 corresponding to the detected parameters to the PCM 60, respectively.

  Next, the engine E includes an intake valve 15 for introducing the intake air supplied from the intake passage 1 (specifically, an intake manifold) into the combustion chamber 17, a fuel injection valve 20 for injecting fuel toward the combustion chamber 17, A piston 23 that reciprocates by combustion of the air-fuel mixture in the combustion chamber 17, a crankshaft 25 that is rotated by reciprocation of the piston 23, and exhaust gas that is generated by combustion of the air-fuel mixture in the combustion chamber 17 And an exhaust valve 27 for discharging to 41.

  Next, the fuel supply system FS includes a fuel tank 30 for storing fuel, and a fuel supply passage 38 for supplying fuel from the fuel tank 30 to the fuel injection valve 20. In the fuel supply passage 38, a low-pressure fuel pump 31, a high-pressure fuel pump 33, and a common rail 35 are provided in order from the upstream side.

Next, the exhaust system EX has an exhaust passage 41 through which the exhaust gas passes. The exhaust passage 41 is rotated by the exhaust gas passing through the exhaust passage 41 in order from the upstream side. A turbine 5b of the turbocharger 5 that drives the compressor 5a, a diesel oxidation catalyst (DOC) 45 having a function of purifying exhaust gas, a diesel particulate filter (DPF) 46, and a passage And an exhaust shutter valve 49 for adjusting the exhaust flow rate. The DOC 45 is a catalyst that oxidizes hydrocarbon (HC), carbon monoxide (CO), and the like using oxygen in the exhaust gas to change it into water and carbon dioxide, and the DPF 46 is a particulate substance ( It is a filter that collects PM (Particulate Matter).
Further, in the exhaust system EX, an exhaust pressure sensor 109 for detecting the exhaust pressure is provided on the exhaust passage 41 upstream of the turbine 5 b of the turbocharger 5, and on the exhaust passage 41 immediately downstream of the DPF 46. Is provided with a linear O ₂ sensor 110 for detecting the oxygen concentration. These various sensors 109 and 110 provided in the exhaust system EX output detection signals S109 and S110 corresponding to the detected parameters to the PCM 60, respectively.

  Further, in the present embodiment, the turbocharger 5 is configured in a small size so as to be able to perform supercharging efficiently even during low-speed rotation with low exhaust energy, and a plurality of movable parts so as to surround the entire circumference of the turbine 5b. Type flaps 5c are provided, and these flaps 5c are configured as a variable geometry turbocharger (VGT) that changes the flow cross-sectional area (nozzle cross-sectional area) of the exhaust gas to the turbine 5b. . For example, the flap 5c is rotated by an actuator with the magnitude of the negative pressure acting on the diaphragm adjusted by an electromagnetic valve. Further, a VGT opening sensor 104 is provided for detecting the opening of the flap 5c (which is the flap opening, hereinafter referred to as “VGT opening” as appropriate) depending on the position of the actuator. The VGT opening sensor 104 outputs a detection signal S104 corresponding to the detected VGT opening to the PCM 60.

  The engine system 200 according to the present embodiment further includes a high pressure EGR device 43 and a low pressure EGR device 48. The high-pressure EGR device 43 connects the exhaust passage 41 upstream of the turbine 5b of the turbocharger 5 and the intake passage 1 downstream of the compressor 5b of the turbocharger 5 (specifically, downstream of the intercooler 8). And a high pressure EGR valve 43b that adjusts the flow rate of exhaust gas that passes through the high pressure EGR passage 43a. The low pressure EGR device 48 includes an exhaust passage 41 on the downstream side of the turbine 5b of the turbocharger 5 (specifically, on the downstream side of the DPF 46 and the upstream side of the exhaust shutter valve 49) and the upstream side of the compressor 5b of the turbocharger 5. A low pressure EGR passage 48a that connects the intake passage 1 of the engine, a low pressure EGR cooler 48b that cools the exhaust gas that passes through the low pressure EGR passage 48a, and a low pressure EGR valve 48c that adjusts the flow rate of the exhaust gas that passes through the low pressure EGR passage 48a. And a low pressure EGR filter 48d.

  The amount of exhaust gas recirculated to the intake system IN by the high pressure EGR device 43 (hereinafter referred to as “high pressure EGR gas amount”) is the exhaust pressure upstream of the turbine 5 b of the turbocharger 5 and the opening of the intake shutter valve 7. It is generally determined by the intake pressure produced by the degree and the opening degree of the high pressure EGR valve 43b. Further, the amount of exhaust gas recirculated to the intake system IN by the low pressure EGR device 48 (hereinafter referred to as “low pressure EGR gas amount”) is the intake pressure on the upstream side of the compressor 5 a of the turbocharger 5 and the exhaust shutter valve 49. Is roughly determined by the exhaust pressure produced by the opening of the valve and the opening of the low pressure EGR valve 48c.

[Electrical configuration]
Next, the electrical configuration of the engine control apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical configuration of the engine control apparatus according to the embodiment of the present invention.

  In addition to the detection signals S101 to S110 of the various sensors 101 to 110 described above, the PCM 60 (engine control device) according to the embodiment of the present invention includes a steering angle sensor 96 that detects the rotation angle of the steering wheel, and the accelerator pedal opening. Detection signals output from an accelerator opening sensor 97 that detects (accelerator opening), a vehicle speed sensor 98 that detects vehicle speed, an outside air temperature sensor 99 that detects outside air temperature, and an atmospheric pressure sensor 100 that detects atmospheric pressure. Based on S96 to S100, control signals S130 to S133 are output in order to control the turbocharger 5, the fuel injection valve 20, the high pressure EGR device 43, and the low pressure EGR device 48.

  The PCM 60 includes a basic target torque determination unit 61 that determines a basic target torque based on the driving state of the vehicle including the operation of the accelerator pedal, and a torque reduction that determines a torque reduction amount based on the driving state of the vehicle that does not include the operation of the accelerator pedal. An amount determination unit 63, a final target torque determination unit 65 that determines a final target torque based on the basic target torque and the torque reduction amount, a torque change filter 67 that smoothes the temporal change of the final target torque, and a final target torque. An engine control unit 69 that controls the engine E to output, a combustion state determination unit 71 that determines a change in the combustion state in the cylinder as the final target torque increases, and a combustion state change by the combustion state determination unit 71 And a final target torque correction unit 73 that corrects the final target torque when it is determined to be large.

  Each component of the PCM 60 includes a CPU, various programs that are interpreted and executed on the CPU (including a basic control program such as an OS and an application program that is activated on the OS to realize a specific function), a program, It is configured by a computer having an internal memory such as a ROM or RAM for storing various data.

[Contents of control]
Next, processing performed by the engine control device will be described with reference to FIGS. FIG. 3 is a flowchart of an engine control process in which the engine control apparatus according to the embodiment of the present invention controls the engine E, and FIG. FIG. 5 is a map showing the relationship between the additional deceleration determined by the engine control apparatus according to the embodiment of the present invention and the steering speed.

The engine control process of FIG. 3 is started and executed repeatedly when the ignition of the vehicle 1 is turned on and power is turned on to the engine control device.
When the engine control process is started, as shown in FIG. 3, in step S1, the PCM 60 acquires the driving state of the vehicle. Specifically, the PCM 60 detects the steering angle detected by the steering angle sensor 96, the accelerator opening detected by the accelerator opening sensor 97, the vehicle speed detected by the vehicle speed sensor 98, and the gear stage currently set for the transmission of the vehicle. The detection signals S96 to S110 output by the various sensors 96 to 110 described above are acquired as the operation state.

  Next, in step S2, the basic target torque setting unit 61 of the PCM 60 sets the target acceleration based on the driving state of the vehicle including the operation of the accelerator pedal acquired in step S1. Specifically, the basic target torque setting unit reads the current vehicle speed and gear stage from acceleration characteristic maps (created in advance and stored in a memory or the like) defined for various vehicle speeds and various gear stages. The acceleration characteristic map corresponding to is selected, and the target acceleration corresponding to the current accelerator opening is determined with reference to the selected acceleration characteristic map.

  Next, in step S3, the basic target torque determining unit 61 determines the basic target torque of the engine E for realizing the target acceleration determined in step S2. In this case, the basic target torque determining unit 61 determines the basic target torque within the range of torque that can be output by the engine E based on the current vehicle speed, gear stage, road surface gradient, road surface μ, and the like.

  Next, in step S4, the torque change filter 67 smoothes the time change of the basic target torque determined in step S3. As a specific method of this smoothing, various known methods (for example, limiting the rate of change of the basic target torque to a threshold value or less, calculating a moving average of the time change of the basic target torque, etc.) are used. be able to.

  In parallel with the processing in steps S2 to S4, in step S5, the torque reduction amount determination unit 63 determines the torque reduction amount based on the driving state of the vehicle other than the operation of the accelerator pedal. Execute. The torque reduction amount determination process will be described with reference to FIG.

  As shown in FIG. 4, when the torque reduction amount determination process is started, in step S21, the torque reduction amount determination unit 63 determines whether or not the absolute value of the steering angle acquired in step S1 is increasing. As a result, when the absolute value of the steering angle is increasing, the process proceeds to step S22, and the torque reduction amount determination unit 63 calculates the steering speed based on the steering angle acquired in step S1.

Next, in step S23, the torque reduction amount determination unit 63 determines whether or not the absolute value of the steering speed is decreasing.
As a result, when the absolute value of the steering speed has not decreased, that is, when the absolute value of the steering speed has increased or the absolute value of the steering speed has not changed, the process proceeds to step S24 and the torque reduction amount determination unit 63 Acquires the target additional deceleration based on the steering speed. This target additional deceleration is a deceleration to be applied to the vehicle in accordance with the steering operation in order to accurately realize the vehicle behavior intended by the driver.

Specifically, the torque reduction amount determination unit 63 acquires the target additional deceleration corresponding to the steering speed calculated in step S22 based on the relationship between the target additional deceleration and the steering speed shown in the map of FIG. .
The horizontal axis in FIG. 5 indicates the steering speed, and the vertical axis indicates the target additional deceleration. As shown in FIG. 5, when the steering speed is less than a threshold value T _S (for example, 10 deg / s), the corresponding target additional deceleration is zero. That is, when the steering speed is less than the threshold value T _S , the control for adding the deceleration to the vehicle according to the steering operation is not performed.
On the other hand, when the steering speed is equal to or higher than the threshold value T _S , the target additional deceleration corresponding to the steering speed gradually approaches a predetermined upper limit value D _max (for example, 1 m / s ² ) as the steering speed increases. That is, as the steering speed increases, the target additional deceleration increases, and the increase rate of the increase amount decreases.

Next, in step S25, the torque reduction amount determination unit 63 determines the additional deceleration in the current process within a range where the increase rate of the additional deceleration is equal to or less than a threshold value Rmax (for example, 0.5 m / s ³ ).
Specifically, when the increase rate from the additional deceleration determined in the previous process to the target additional deceleration determined in step S24 of the current process is equal to or less than Rmax, the torque reduction amount determining unit 63 determines in step S24. The determined target additional deceleration is determined as the additional deceleration in the current process.
On the other hand, when the rate of change from the additional deceleration determined in the previous process to the target additional deceleration determined in step S24 of the current process is larger than Rmax, the torque reduction amount determination unit 63 adds the value determined in the previous process. The value increased by the increase rate Rmax from the acceleration / deceleration until the current processing is determined as the additional deceleration in the current processing.

  If the absolute value of the steering speed is decreasing in step S23, the process proceeds to step S26, where the torque reduction amount determination unit 63 determines the additional deceleration determined in the previous process as the additional deceleration in the current process. To do. That is, when the absolute value of the steering speed is decreasing, the additional deceleration at the maximum steering speed (that is, the maximum value of the additional deceleration) is held.

In step S21, if the absolute value of the steering angle is not increasing (constant or decreasing), the process proceeds to step S27, where the torque reduction amount determination unit 63 sets the additional deceleration determined in the previous process this time. The amount to be reduced (deceleration reduction amount) is acquired in the process. The deceleration reduction amount is calculated based on, for example, a constant reduction rate (for example, 0.3 m / s ³ ) stored in advance in a memory or the like. Alternatively, it is calculated based on the reduction rate determined according to the driving state of the vehicle acquired in step S1 and the steering speed calculated in step S22.

  In step S28, the torque reduction amount determination unit 63 determines the additional deceleration in the current process by subtracting the deceleration decrease acquired in step S27 from the additional deceleration determined in the previous process.

  After step S25, S26, or S28, in step S29, the torque reduction amount determination unit 63 determines the torque reduction amount based on the current additional deceleration determined in step S25, S26, or S28. Specifically, the torque reduction amount determination unit 63 determines the torque reduction amount necessary for realizing the current additional deceleration based on the current vehicle speed, gear stage, road surface gradient, etc. acquired in step S1. To do. After this step S29, the torque reduction amount determination unit 63 ends the torque reduction amount determination processing and returns to the main routine.

  Returning to FIG. 3, after performing the processing of steps S2 to S4 and the torque reduction amount determination processing of step S5, in step S6, the final target torque determination unit 65 performs the basic target torque after smoothing in step S4. From this, the final target torque is determined by subtracting the torque reduction amount determined in the torque reduction amount determination process in step S5.

Next, in step S7, the combustion state determination unit 71 of the PCM 60 obtains the rising speed of the final target torque from the final target torque determined in step S6 and the final target torque set in the previous process. It is determined whether the ascending speed exceeds a predetermined determination threshold. In step S7, the combustion state determination unit 71 determines whether or not the change in the combustion state in the cylinder accompanying the increase in the final target torque is large, based on the increase rate of the final target torque. It is determined whether or not a change in the combustion state that causes a decrease in stability, emission performance, or drivability occurs. From this point of view, the judgment threshold is set so that the change in the combustion state in the cylinder increases as the final target torque increases, that is, the combustion stability, emission performance, and drivability decrease due to the change in the combustion state. A value corresponding to the rising speed of the final target torque is applied. Typically, a fixed value set in advance is applied to the determination threshold.
In one example, the determination threshold value is the torque reduction amount determined by the torque reduction amount determination unit 63 at this time when an operation of turning back after turning the steering is performed at a predetermined steering speed or higher or within a predetermined time. Is set based on the rising speed of the final target torque to which is applied. When such a steering operation is performed, the final target torque is rapidly increased in order to quickly reduce the applied torque reduction amount toward 0, so that the inside of the cylinder accompanying the increase in the final target torque is increased. It is because it is assumed that the change of the combustion state becomes large.
In another example, the determination threshold value is determined when the accelerator pedal is depressed more than a predetermined opening degree while the torque reduction amount is applied to the final target torque (that is, the change amount of the accelerator pedal opening is a predetermined amount). (When it is the above), it is set based on the rising speed of the final target torque to which the basic target torque according to the accelerator pedal operation is applied. When such an accelerator operation is performed, the final target torque is rapidly increased to satisfy the acceleration request from the driver, so that the change in the combustion state in the cylinder accompanying the increase in the final target torque is large. This is because it is assumed.
Note that the increase speed of the final target torque described above corresponds to the amount of change (the increase amount) of the final target torque per unit time, and is synonymous with the increase rate and the increase degree of the final target torque.

As a result of the determination in step S7, when it is determined that the increase speed of the final target torque exceeds the determination threshold (step S7: Yes), the process proceeds to step S8, and the final target torque correction unit 73 of the PCM 60 increases the final target torque. In order to limit the speed, the final target torque determined in step S6 is corrected. Specifically, the final target torque correction unit 73 performs correction to reduce the final target torque determined in step S6 so that the increase speed of the final target torque is equal to or less than the determination threshold value. For example, the final target torque correction unit 73 determines the final target torque to be applied this time based on the final target torque set in the previous process so that the rising speed of the final target torque exceeding the determination threshold matches the determination threshold. To do.
After such processing in step S8, the process proceeds to step S9. On the other hand, as a result of the determination in step S7, when it is not determined that the increase speed of the final target torque exceeds the determination threshold value (step S7: No), that is, when the increase speed of the final target torque is equal to or less than the determination threshold value, The process proceeds to step S9 without performing the process of step S8. In this case, the final target torque determined in step S6 is not corrected and is used as it is.

  Next, in step S9, the engine control unit 69 performs the required injection to be injected from the fuel injection valve 20 based on the final target torque set in step S6 or the final target torque corrected in step S8 and the engine speed. Set the amount.

  Subsequently, in step S10, the engine control unit 69 determines the fuel injection pattern, the fuel pressure, the target oxygen concentration, the target intake air temperature, based on the required injection amount set in step S9 and the engine speed. An EGR control mode (a mode in which both or one of the high pressure EGR device 43 and the low pressure EGR device 48 is operated or a mode in which neither the high pressure EGR device 43 nor the low pressure EGR device 48 is operated) is set.

  Next, in step S11, the engine control unit 69 sets state quantities for realizing the target oxygen concentration and target intake air temperature set in step S10. For example, this state quantity includes the amount of exhaust gas recirculated to the intake system IN by the high pressure EGR device 43 (high pressure EGR gas amount) and the amount of exhaust gas recirculated to the intake system IN by the low pressure EGR device 48 (low pressure EGR gas amount). And a supercharging pressure by the turbocharger 5 is included.

  Next, in step S12, the engine control unit 69 controls each actuator that drives each component of the engine system 200 based on the state quantity set in step S11. In this case, the engine control unit 69 sets a limit value or a limit range according to the state quantity, and sets the control amount of each actuator such that the state value complies with the limit value or the limit range. To do. After such step S12, the PCM 60 ends the engine control process.

  Next, the operation of the engine control apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing time changes in parameters related to engine control by the engine control device when a vehicle equipped with the engine control device according to the embodiment of the present invention turns.

  FIG. 6A is a plan view schematically showing a vehicle that makes a right turn. As shown in FIG. 6A, the vehicle 1 starts turning right from position A and continues turning right from position B to position C with a constant steering angle.

FIG. 6B is a diagram showing changes in the steering angle of the vehicle that turns right as shown in FIG. In FIG. 6B, the horizontal axis indicates time, and the vertical axis indicates the steering angle.
As shown in FIG. 6B, rightward steering is started at the position A, and the rightward steering angle is gradually increased by performing the steering addition operation, and the rightward steering angle is maximized at the position B. It becomes. Thereafter, the steering angle is kept constant up to position C (steering holding).

FIG. 6C is a diagram showing a change in the steering speed of the vehicle that turns right as shown in FIG. In FIG. 6B, the horizontal axis indicates time, and the vertical axis indicates the steering speed.
The steering speed of the vehicle is expressed by time differentiation of the steering angle of the vehicle. That is, as shown in FIG. 6C, when the rightward steering is started at the position A, a rightward steering speed is generated, and the steering speed is kept substantially constant between the position A and the position B. Thereafter, the rightward steering speed decreases, and when the rightward steering angle becomes maximum at the position B, the steering speed becomes zero. Further, the steering speed remains zero while the rightward steering angle is maintained from position B to position C.

  FIG. 6D is a diagram showing a change in the additional deceleration determined based on the steering speed shown in FIG. In FIG. 6D, the horizontal axis indicates time, and the vertical axis indicates additional deceleration. Also, the solid line in FIG. 6D indicates the change in the additional deceleration determined in the torque reduction amount determination process in FIG. 4, and the alternate long and short dash line indicates the change in the target additional deceleration based on the steering speed. Similar to the change in the steering speed shown in FIG. 6C, the target additional deceleration indicated by the alternate long and short dash line starts to increase from the position A and is kept substantially constant between the position A and the position B, and thereafter Decrease to zero at position B.

As described with reference to FIG. 4, the torque reduction amount determining unit 63 determines that the absolute value of the steering speed has not decreased in step S23, that is, the absolute value of the steering speed has increased or the absolute value of the steering speed has not increased. If the value has not changed, the target additional deceleration is acquired based on the steering speed in step S24. Subsequently, in step S25, the torque reduction amount determination unit 63 determines the additional deceleration in each processing cycle in a range where the increase rate of the additional deceleration is equal to or less than the threshold value Rmax.
FIG. 6D shows a case where the increase rate of the target additional deceleration that has started increasing from the position A exceeds the threshold value Rmax. In this case, the torque reduction amount determination unit 63 increases the additional deceleration so that the increase rate = Rmax (that is, at a slower increase rate than the target additional deceleration indicated by the one-dot chain line). When the target additional deceleration is kept substantially constant between the position A and the position B, the torque reduction amount determination unit 63 determines that the additional deceleration is equal to the target additional deceleration.

  Further, as described above, when the absolute value of the steering speed is decreased in step S23 of FIG. 4, the torque reduction amount determination unit 63 holds the additional deceleration at the maximum steering speed. In FIG. 6 (d), when the steering speed decreases toward the position B, the target additional deceleration indicated by the alternate long and short dash line decreases accordingly, but the maximum value of the additional deceleration indicated by the solid line reaches the position B. maintain.

  Furthermore, as described above, when the absolute value of the steering angle is constant or decreasing in step S21 of FIG. 4, the torque reduction amount determination unit 63 acquires the deceleration reduction amount in step S27, and the deceleration is obtained. Addition deceleration is decreased by the amount of decrease. In FIG. 6 (d), the torque reduction amount determination unit 63 adds an additional deceleration so that the rate of decrease of the additional deceleration gradually decreases, that is, the slope of the solid line indicating the change of the additional deceleration gradually decreases. Decrease acceleration / deceleration.

FIG. 6E is a diagram showing a change in the torque reduction amount determined based on the additional deceleration shown in FIG. In FIG. 6E, the horizontal axis indicates time, and the vertical axis indicates the torque reduction amount.
As described above, the torque reduction amount determination unit 63 determines the torque reduction amount necessary for realizing the additional deceleration based on parameters such as the current vehicle speed, gear stage, and road surface gradient. Therefore, when these parameters are constant, the torque reduction amount is determined so as to change in the same manner as the change in the additional deceleration shown in FIG.

FIG. 6F is a diagram showing changes in the basic target torque before and after smoothing by the torque change filter 67. In FIG. 6F, the horizontal axis indicates time, and the vertical axis indicates torque. Further, the dotted line in FIG. 6F indicates the basic target torque before smoothing by the torque change filter 67, and the solid line indicates the basic target torque after smoothing by the torque change filter 67.
The basic target torque determined so as to achieve the target acceleration set based on the accelerator opening, the vehicle speed, the gear stage, etc. is steep due to various disturbances, noise, etc., as indicated by the dotted line in FIG. May include changes. By smoothing the basic target torque by the torque change filter 67, a steep change is suppressed as shown by a solid line in FIG. 8F, and a rapid acceleration / deceleration of the vehicle is suppressed.

FIG. 6G is a diagram showing changes in the final target torque determined based on the basic target torque and the torque reduction amount. In FIG. 6G, the horizontal axis represents time, and the vertical axis represents torque. Further, the dotted line in FIG. 6 (g) indicates the basic target torque after smoothing shown in FIG. 6 (f), and the solid line indicates the final target torque. More specifically, the alternate long and short dash line indicates the final target torque in addition to the solid line, the alternate long and short dash line indicates the final target torque before correction, and the solid line indicates the final target torque after correction.
As described with reference to FIG. 3, the final target torque determination unit 65 subtracts the torque reduction amount determined in the torque reduction amount determination process in step S5 from the basic target torque after smoothing in step S4. By doing so, the final target torque is determined. Of the basic target torque and torque reduction amount used to determine the final target torque, the smoothing by the torque change filter 67 is performed based on the basic state determined based on the driving state of the vehicle including the operation of the accelerator pedal. Only target torque. In other words, in the time change of the final target torque, the time change corresponding to the torque reduction amount determined based on the steering operation that is a driving state other than the operation of the accelerator pedal is not smoothed by the torque change filter 67. . Therefore, as shown by a solid line in FIG. 6G, the torque reduction amount is reflected on the final target torque as it is without being smoothed by the torque change filter 67.
On the other hand, after position B, the torque reduction amount decreases to decrease the additional deceleration and the final target torque increases. At this time, in step S7 of FIG. However, it determines with the raise speed | rate of the final target torque determined in step S6 of FIG. 3 exceeding a determination threshold value. Therefore, as shown by the one-dot chain line and the solid line in FIG. 6 (g), in step S8 in FIG. 3, the final target torque correction unit 73 restricts the rising speed of the final target torque to be equal to or lower than the determination threshold value. Correction to reduce Specifically, the final target torque correction unit 73 increases the final target torque at a speed corresponding to the determination threshold while the increase speed of the final target torque determined in step S6 exceeds the determination threshold. The final target torque is corrected (in FIG. 6G, the final target torque indicated by the solid line applied instead of the final target torque indicated by the alternate long and short dash line is the torque corresponding to the determination threshold value). Thereafter, the rising speed of the final target torque determined in step S6 becomes equal to or less than the determination threshold value, and this final target torque is applied as it is.

FIG. 6H is a diagram showing a change in the fuel injection amount determined based on the final target torque. In FIG. 6H, the horizontal axis indicates time, and the vertical axis indicates the required injection amount. Also, the dotted line in FIG. 6 (h) indicates the required injection amount corresponding to the basic target torque after smoothing shown in FIG. 6 (f), and the solid line corresponds to the final target torque shown in FIG. 6 (g). Indicates the required injection amount.
In the example of FIG. 6 (h), the engine control unit 69 performs the fuel injection valve for the time change corresponding to the torque reduction amount in the time change of the final target torque set in step S6 or the final target torque corrected in step S8. Control is performed according to the amount of fuel injected from 20. Therefore, the required injection amount changes in the same manner as the time change of the final target torque shown in FIG. 6G, as shown by the solid line in FIG.

6 (i) shows a vehicle in which steering is performed as shown in FIG. 6 (b) and the engine E is controlled to achieve the final target torque shown in FIG. 6 (g). When the control corresponding to the change in the yaw rate (actual yaw rate) generated in FIG. 6 and the torque reduction amount shown in FIG. 6E is not performed (that is, the basic target after smoothing indicated by the dotted line in FIG. 6G) It is a diagram which shows the change of the actual yaw rate in the case of controlling the engine E so as to realize torque. In FIG. 6 (i), the horizontal axis indicates time, and the vertical axis indicates the yaw rate. Also, the solid line in FIG. 6 (i) shows the change in the actual yaw rate when the engine E is controlled to achieve the final target torque, and the dotted line is the case where the control corresponding to the torque reduction amount is not performed. The change in the actual yaw rate is shown.
When the rightward steering is started at the position A and the torque reduction amount is increased as shown in FIG. 6E as the rightward steering speed increases, the load on the front wheels, which are the steering wheels of the vehicle, increases. As a result, the frictional force between the front wheels and the road surface increases, and the cornering force of the front wheels increases, so that the turning performance of the vehicle is improved. That is, as shown in FIG. 6 (i), the final target torque reflecting the torque reduction amount is set between the position A and the position B, compared with the case where the control corresponding to the torque reduction amount is not performed (dotted line). When the engine E is controlled so as to be realized (solid line), the clockwise (CW) yaw rate generated in the vehicle becomes larger.
Further, as shown in FIGS. 6D and 6E, when the steering speed decreases toward the position B, the target additional deceleration also decreases, but the torque reduction amount is maintained at the maximum value. While the steering cut is continued, the load applied to the front wheels is maintained, and the turning ability of the vehicle is maintained.
Further, when the absolute value of the steering angle is constant from the position B to the position C, the torque reduction amount is smoothly reduced. Therefore, the load applied to the front wheels is gradually reduced according to the end of the steering incision. By reducing the cornering force, the output torque of the engine E is recovered while stabilizing the vehicle body.

[Function and effect]
Next, functions and effects of the engine control apparatus according to the embodiment of the present invention will be described.

  In this embodiment, when the torque reduction amount is decreased by the torque reduction amount determination unit 63 and the final target torque determined by the final target torque determination unit 65 increases, the increase speed of the final target torque sets the determination threshold value. When exceeding, the combustion state determination unit 71 determines that the change in the combustion state in the cylinder accompanying the increase in the final target torque is large, and the final target torque correction unit 73 sets the increase speed of the final target torque to be equal to or less than the determination threshold value. The final target torque is corrected so that As a result, it is possible to appropriately limit the rate of increase of the engine torque, and to suppress a decrease in combustion stability, emission performance, and drivability of the engine E.

  In particular, in the present embodiment, when an operation of turning back the steering threshold after turning the steering wheel at a predetermined steering speed or higher is performed at this time, the torque reduction amount is determined at this time. Since it is set based on the rising speed of the final target torque to which the torque reduction amount determined by the unit 63 is applied, it is possible to suppress a large change in the combustion state that is likely to occur when such a steering operation is performed. Thus, the combustion stability, emission performance, and drivability of the engine E can be appropriately ensured.

  In addition, in the present embodiment, an operation is performed in which the accelerator pedal is depressed more than a predetermined opening degree while the determination threshold for determining the rising speed of the final target torque is applied to the final target torque. In this case, it is set based on the speed of increase of the final target torque according to the accelerator pedal operation, so that a large change in the combustion state that is likely to occur when such an accelerator pedal operation is performed is suppressed. Thus, the combustion stability, emission performance, and drivability of the engine E can be appropriately ensured.

  Further, according to the present embodiment, the torque reduction amount is determined according to the steering operation of the vehicle, so that the time change of the torque reduction amount determined based on the steering operation can be reflected in the time change of the final target torque. As a result, a deceleration according to the driver's steering operation can be quickly applied to the vehicle, a load is applied to the front wheels, and the cornering force can be rapidly increased to improve the response to the steering operation and stabilize the combustion. The engine E can be controlled so as to accurately realize the vehicle behavior intended by the driver while ensuring the performance.

  Further, according to the present embodiment, the torque reduction amount is determined so as to increase the torque reduction amount and reduce the increase rate of the increase amount as the steering speed of the vehicle increases. When the steering speed of the vehicle starts to increase, the amount of torque reduction can be increased rapidly, thereby quickly adding deceleration to the vehicle at the start of vehicle steering and applying sufficient load to the steering wheel. Can be quickly added to some front wheels. As a result, the frictional force between the front wheels, which are the steering wheels, and the road surface increase, and the cornering force of the front wheels increases, so that the turning ability of the vehicle at the beginning of the curve approach can be improved, and combustion stability is ensured. On the other hand, the responsiveness to the steering operation can be improved.

  According to the present embodiment, the target acceleration of the vehicle is determined based on the driving state of the vehicle including the operation of the accelerator pedal, and the basic target torque is determined based on the target acceleration. The engine E can be controlled to accurately realize the acceleration intended by the driver.

  According to the present embodiment, the engine control device is a diesel engine control device including a fuel injection device that injects fuel into the cylinder, and the engine control unit 69 outputs the final target torque to the diesel engine. Since the fuel injection amount of the fuel injection valve 20 is controlled so as to change, the time change of the torque reduction amount determined based on the driving state of the vehicle other than the operation of the accelerator pedal is changed by changing the fuel injection amount. Thus, the engine E can be controlled to accurately realize the vehicle behavior intended by the driver.

[Modification]
In the above-described embodiment, it has been described that the torque reduction amount determination unit 63 acquires the target additional deceleration based on the steering speed and determines the torque reduction amount based on the target additional deceleration, but other than the operation of the accelerator pedal. The torque reduction amount may be determined based on the driving state of the vehicle (steering angle, yaw rate, slip ratio, etc.).
For example, the torque reduction amount determination unit 63 calculates a target yaw acceleration to be generated in the vehicle based on the target yaw rate calculated from the steering angle and the vehicle speed or the yaw rate input from the yaw rate sensor, and the target yaw acceleration is calculated based on the target yaw acceleration. The additional deceleration may be acquired to determine the torque reduction amount. Alternatively, a lateral acceleration generated as the vehicle turns may be detected by an acceleration sensor, and the torque reduction amount may be determined based on the lateral acceleration.

  In the above-described embodiment, the change in the combustion state in the cylinder is determined based on the rising speed of the final target torque, and the final target torque is corrected. In other examples, the final target torque is corrected. The final target torque may be corrected by determining the change in the combustion state in the cylinder based on the additional deceleration corresponding to the torque increase rate or the increase rate (increase rate) of the torque reduction amount. In this case as well, the additional deceleration and the increase rate of the torque reduction amount (increase rate) are set based on the increase rate of the final target torque that causes a change in the combustion state that leads to a decrease in combustion stability, emission performance, and drivability. It is preferable to set a determination threshold value for determination.

DESCRIPTION OF SYMBOLS 1 Intake passage 5 Turbocharger 5a Compressor 5b Turbine 5c Flap 20 Fuel injection valve 41 Exhaust passage 43 High pressure EGR device 48 Low pressure EGR device 60 PCM
61 Basic target torque determination unit 63 Torque reduction amount determination unit 65 Final target torque determination unit 67 Torque change filter 69 Engine control unit 71 Combustion state determination unit 73 Final target torque correction unit 200 Engine system E engine

Claims (7)

An engine control device that controls an engine based on a driving state of a vehicle,
Basic target torque determining means for determining a basic target torque based on the driving state of the vehicle including the operation of an accelerator pedal;
Torque reduction amount determination means for determining a torque reduction amount for reducing the basic target torque based on the driving state of the vehicle other than the operation of the accelerator pedal, wherein the torque reduction amount determination means is the driving state of the vehicle. The torque reduction amount determining means for increasing the torque reduction amount when the pressure changes, and subsequently reducing the torque reduction amount toward 0.
Final target torque determining means for determining a final target torque based on the basic target torque and the torque reduction amount;
Engine control means for controlling the engine to output the final target torque;
Have
Furthermore,
When the torque reduction amount is reduced by the torque reduction amount determination means and the final target torque determined by the final target torque determination means increases, does the final target torque increase rate exceed a predetermined determination threshold? Combustion state determination means for determining a change in the combustion state in the cylinder accompanying the increase in the final target torque according to whether or not,
When the increase speed of the final target torque exceeds the determination threshold value, and the combustion state determination means determines that the change in the combustion state is large, the increase speed of the final target torque is limited to the determination threshold value or less. A final target torque correcting means for correcting the final target torque,
An engine control device comprising:   The engine control apparatus according to claim 1, wherein the torque reduction amount determination unit determines the torque reduction amount in accordance with a steering operation of the vehicle.   The determination threshold is an increase speed of the final target torque to which the torque reduction amount determined by the torque reduction amount determination means is applied when an operation of turning back after turning the steering is performed at a predetermined steering speed or higher. The engine control device according to claim 2, wherein the engine control device is set based on the setting.   The determination threshold is set such that an accelerator pedal is depressed more than a predetermined opening degree while the torque reduction amount determined according to the steering operation by the torque reduction amount determination means is applied to the final target torque. The engine control device according to claim 2, wherein the engine control device is set based on a rising speed of the final target torque according to the accelerator pedal operation.   The torque reduction amount determining means determines the torque reduction amount so as to increase the torque reduction amount and reduce the increase rate of the increase amount as the steering speed of the vehicle increases. The engine control device according to any one of the above.   6. The basic target torque determining means determines a target acceleration of the vehicle based on a driving state of the vehicle including an operation of the accelerator pedal, and determines the basic target torque based on the target acceleration. The engine control device according to one item. The engine control device is a diesel engine control device including a fuel injection device that injects fuel into a cylinder.
The engine control device according to any one of claims 1 to 6, wherein the engine control means controls a fuel injection amount of the fuel injection device so as to output the final target torque to the diesel engine.

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