JP6123222B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device that controls the operation of an engine mounted on a vehicle when starting.

  2. Description of the Related Art Conventionally, there has been known control for reducing an intake air amount from during cranking to immediately after starting for the purpose of suppressing output fluctuation and reducing emission at the time of engine start and restart. That is, the upper limit value of the throttle opening is limited during a predetermined period from the start of engine start.

  In general, if the throttle opening at the start is greatly opened, the intake amount increases and the engine output tends to increase excessively. Also, if the negative pressure in the intake pipe is small, unburned fuel adhering to the intake port Since it becomes difficult to evaporate, the combustibility of the air-fuel mixture in the cylinder changes, and the unburned components in the exhaust gas easily increase. On the other hand, if the throttle opening is reduced to a small value, output variations and exhaust gas performance degradation are suppressed (see, for example, Patent Document 1).

JP 2007-224848 A

  However, it is difficult to appropriately respond to the driver's acceleration request with the conventional method of reducing the intake air amount for a predetermined time based on the start of the engine. For example, in a vehicle equipped with an idle stop system that automatically stops and restarts the engine, when the engine is started with the vehicle stopped, the rotational speed of the engine is prevented from excessively rising. While this can be ensured, the response when the vehicle is to be accelerated as the engine starts is reduced. On the other hand, if the driver's acceleration demand increases, if the intake amount is increased immediately after the complete explosion of the engine, the engine output suddenly increases and the engine output becomes excessive, causing a shock. There is. In addition, exhaust emission may deteriorate with sudden changes in the intake air amount.

As described above, the conventional methods have a problem that it is difficult to meet various needs such as maintaining rotational stability immediately after start-up, preventing occurrence of shock, improving environmental performance, and improving responsiveness and acceleration performance.
One of the objects of the present invention was devised in view of the above problems, and is to provide an engine control device that improves drivability while ensuring engine startability and exhaust gas performance. The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

(1) An engine control device disclosed herein is an engine control device that controls an operation of an engine mounted on a vehicle at the time of starting, and calculates an opening for calculating a target opening that is a control target value of the throttle opening of the engine. A degree calculating means, a restricting means for restricting the target opening at the start of the engine to an upper limit value or less, and a restriction on the target opening when the rate of change of the rotational speed of the engine is less than a predetermined change rate. And release means for releasing. The release means is configured to provide the target when the advance margin until the ignition timing at which the engine generates maximum actual torque is equal to or less than a predetermined value and the rate of change of the rotational speed of the engine is less than a predetermined rate of change. Cancel the opening restriction.

(2) Also, the releasing means, based on the intake system pressure of the engine, it is preferable to remove the limit of the target opening performed by the limiting means.
The intake system pressure is a pressure actually measured in the intake system of the engine, and includes, for example, measured values such as an intake manifold pressure (intake manifold pressure), a surge tank internal pressure, an intake pipe pressure, and an atmospheric pressure.

( 3 ) Also, an air amount calculating means for calculating a target air amount, which is a target value of the air amount introduced into the cylinder of the engine, and the intake system pressure when the engine obtains the target air amount It is preferable to include a pressure calculation means for calculating a target pressure to be performed. In this case, it is preferable that the releasing means cancels the restriction on the target opening when the target pressure is equal to or higher than the actually measured value of the intake system pressure.
The target air amount is preferably calculated based on, for example, an accelerator operation amount, an external load of the engine, an operating state of the engine, and the like.

( 4 ) It is preferable that a volume efficiency coefficient calculating unit that calculates a volume efficiency coefficient corresponding to a value obtained by standardizing the volume efficiency of the engine based on the intake system pressure is provided. In this case, it is preferable that the pressure calculating unit calculates the target pressure based on the target air amount and the volumetric efficiency coefficient.
The intake system pressure means a pressure detected in the intake system of the engine, such as the intake manifold pressure, the downstream pressure of the throttle valve, the upstream pressure, or the atmospheric pressure. In addition, it is preferable that the said volume efficiency coefficient converts the said volume efficiency into the value when the said intake manifold pressure is atmospheric pressure.

( 5 ) Moreover, it is preferable that the said limitation means sets the said upper limit based on the cooling water temperature of the said engine.
( 6 ) Further, the limiting means includes a first upper limit value that is the upper limit value during cranking until the engine starts, and a second upper limit value that is the upper limit value after the engine starts. It is preferable to set them separately.

( 7 ) Further, the release means releases the restriction on the target opening when the elapsed time after starting the engine exceeds a predetermined time, and the restriction when the engine is started from an idle stop state. The second time until the restriction is released may be set shorter than the first time until the release, when starting from another state (when starting the engine excluding starting from the idle stop state). preferable.
( 8 ) Moreover, it is preferable that the said cancellation | release means cancels | releases the restriction | limiting of the said target opening degree by the said restriction | limiting means at the time of the said engine stop.

  According to the disclosed engine control device, excessive output and exhaust gas deterioration can be suppressed by limiting the target opening of the throttle valve to the upper limit value or less when the engine is started. On the other hand, by removing this restriction when the rate of change in the engine speed is less than the predetermined rate of change, the degree of increase in the engine speed immediately after engine startup can be immediately reflected in the intake air amount. Therefore, acceleration performance can be improved while maintaining start stability and environmental performance, and drivability at start-up can be improved.

It is a figure which illustrates the block configuration of the engine control apparatus which concerns on one Embodiment, and the structure of the engine to which this control apparatus was applied. It is a block block diagram of the request | requirement torque calculating part of this engine control apparatus. It is a block block diagram of the torque upper limit calculating part of this engine control apparatus. It is a block block diagram which illustrates the setting method of the upper limit rotational speed in the rotational speed upper limit setting part of FIG. It is an example of the graph which concerns on the calculation in the torque upper limit calculating part of this engine control apparatus, (a) is a relationship between an upper limit rotational speed, the operation position of a select lever, and an accelerator operation amount, (b) is an upper limit rotational speed. The relationship between the operation position of the select lever and the coolant temperature, (c) shows the relationship between the upper limit rotational speed and the brake fluid pressure. Further, (d) shows the relationship between the cooling water temperature and the offset amount, and (e) shows the relationship between the rotational speed difference and the upper limit gradient. It is a graph for demonstrating one of the completion conditions of upper limit control in this engine control apparatus, (a) corresponds to the case where there is no accelerator operation, (b) corresponds to the case where an accelerator operation is made. . It is a block block diagram which illustrates the calculation content in the target torque calculating part of this engine control apparatus. It is a block block diagram of the throttle opening restriction part at the time of starting of this engine control device. It is a graph which illustrates the relationship between the upper limit set with this engine control apparatus, and cooling water temperature. It is a graph which illustrates the relationship between the volumetric efficiency coefficient set by this engine control apparatus, a pressure ratio, and an actual rotational speed. It is a block block diagram of the opening restriction cancellation | release part of this engine control apparatus. It is a figure for demonstrating the effect | action of this engine control apparatus, (a) is a graph which illustrates the fluctuation | variation of an actual rotational speed when upper limit control is implemented at the time of restart from an idle stop state, (b), (C) is a graph which each illustrates the fluctuation | variation of a target torque and ignition timing. It is a figure for demonstrating the effect | action of this engine control apparatus, (a) is a graph which illustrates the fluctuation | variation of a brake operation amount, (b) is a graph which illustrates the fluctuation | variation of an actual rotational speed. It is a figure for demonstrating the effect | action of this engine control apparatus, (a) is a graph which illustrates the fluctuation | variation of a brake operation amount, (b) is a graph which illustrates the fluctuation | variation of an accelerator operation amount, (c) is an actual rotational speed. It is a graph which illustrates variation of. It is a flowchart of the opening degree restriction control in this engine control device. 4 is a time chart for explaining the operation of the engine control device, wherein (a) is a brake operation amount, (b) is an accelerator operation amount, (c) is an actual rotational speed, (d) is an actual intake manifold pressure and a target intake manifold. Pressure (e) corresponds to the target throttle area.

  An engine control apparatus applied to a vehicle will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. Device configuration]
[1-1. Power transmission system]
The engine control apparatus of this embodiment is applied to the vehicle-mounted engine 10 shown in FIG. The output of the engine 10 is transmitted to the drive wheels 27 of the vehicle via an automatic transmission unit 26 (automatic transmission, hereinafter referred to as AT unit). The AT unit 26 includes a torque converter 26a and a transmission mechanism 26b.

  The torque converter 26a is a power transmission device that increases the torque while transmitting the rotation of the engine 10 to the speed change mechanism 26b via a fluid. A typical torque converter 26a has a structure in which three types of impellers including a driving impeller (pump impeller), a passive impeller (turbine liner), and a guide plate (stator) and a working fluid are enclosed in a casing. . The rotating shaft of the driving impeller (input shaft of the torque converter 26a) is connected to the output shaft of the engine 10, and the rotating shaft of the passive impeller (output shaft of the torque converter 26a) is connected to the transmission mechanism 26b side. Further, the guide plate is disposed between the driving impeller and the passive impeller that are disposed to face each other, and is fixed to the casing.

  The working fluid of the torque converter 26a circulates in the casing while transmitting torque applied from the driving impeller to the passive impeller and the guide plate. Generally, the magnitude of the torque acting on the guide plate increases as the rotational speed difference between the driving impeller and the passive impeller increases, and the magnitude of the torque transmitted to the passive impeller is equal to the torque of the driving impeller. This is the sum of the torque acting on the guide plate. Therefore, when the rotational speed of the output shaft of torque converter 26a is smaller than the rotational speed of the input shaft, the torque transmitted to transmission mechanism 26b is amplified more than the torque of engine 10.

The speed change mechanism 26 b is a power transmission device for reducing the rotational speed input from the torque converter 26 a and transmitting it to the drive wheels 27. The specific structure of the speed change mechanism 26b is arbitrary. For example, a planetary gear mechanism, a CVT mechanism, a clutch / brake mechanism, etc. (not shown) may be incorporated.
A planetary gear mechanism is a transmission mechanism having a structure in which a sun gear (sun gear) and a plurality of planetary gears (planetary gears) are provided inside an outer ring gear (outer gear), and the center axes of the planetary gears are connected by a planet carrier. is there. In the case of the speed change mechanism 26b provided with this planetary gear mechanism, a plurality of types of speed change ratios are realized by limiting the rotation operations of the three rotating elements of the outer ring gear, the sun gear, and the planet carrier.

The CVT mechanism is a transmission mechanism that can continuously change the rotation speed. In the case of the speed change mechanism 26b having a belt-type CVT mechanism that transmits power via a belt suspended on the conical surfaces of two pulleys, the belt suspension position is moved continuously with respect to the conical surface of the pulley. A transmission ratio is realized.
The clutch / brake mechanism is a mechanism for connecting / disconnecting power transmission by controlling the magnitude of the frictional force generated between opposing frictional engagement elements or by restricting the movement of the frictional engagement elements. For example, at the time of shifting by the planetary gear mechanism or when the vehicle is stopped, the clutch / brake mechanism is controlled to be in a disconnected / fixed state, and transmission of the driving force to the drive wheel 27 side is cut off.

  The speed ratio in the speed change mechanism 26b is changed according to the operation position (shift position) of the select lever provided in the vehicle interior. In this embodiment, four types of operation positions of “P (parking) range”, “R (reverse) range”, “N (neutral) range”, and “D (drive) range” are set as the operation position of the select lever. Has been. Of the above ranges, the P range and the N range are both selected when the vehicle is stopped, and are also referred to as non-traveling ranges. On the other hand, the D range is also called a travel range. The R range is a range that is selected when the vehicle travels toward the rear of the vehicle, and is included in a broad travel range.

[1-2. Cylinder structure]
Next, the cylinder structure of the engine 10 will be described. The engine 10 is, for example, an internal combustion engine (gasoline engine, diesel engine) that uses gasoline or light oil as fuel. FIG. 1 shows one cylinder among a plurality of cylinders provided in the multi-cylinder engine 10. The piston 16 that reciprocates in the cylinder is connected to the crankshaft 17 via a connecting rod. The crankshaft 17 is an output shaft connected to the drive impeller of the torque converter 26a described above.

A spark plug 13 is provided at the top of the cylinder with its tip projecting toward the combustion chamber. An intake port 11 and an exhaust port 12 are provided on the top surface of the combustion chamber on the cylinder head side.
On the top surface of the combustion chamber, an intake valve 14 that opens and closes an opening communicating with the intake port 11 and an exhaust valve 15 that opens and closes an opening communicating with the exhaust port 12 are provided. The intake port 11 and the combustion chamber are communicated or closed by opening and closing the intake valve 14, and the exhaust port 12 and the combustion chamber are communicated or blocked by opening and closing the exhaust valve 15.

The upper ends of the intake valve 14 and the exhaust valve 15 are each connected to one end of a rocker arm in a variable valve mechanism (not shown). The rocker arm is a rocking member that is pivotally supported by the rocker shaft, and the intake valve 14 and the exhaust valve 15 are reciprocated in the vertical direction by the rocking of each rocker arm. The variable valve mechanism is a mechanism for changing the maximum valve lift amount and the valve timing individually or in conjunction with each of the intake valve 14 and the exhaust valve 15.
Around the cylinder, a water jacket 19 through which engine coolant flows is provided. The engine coolant is a refrigerant for cooling the engine 10 and circulates in the coolant circulation path that connects the water jacket 19 and the radiator in a ring shape.

[1-3. Intake system]
An injector 18 for injecting fuel is provided in the intake port 11. The amount of fuel injected from the injector 18 is electronically controlled by the engine control device 1 described later. Further, an intake manifold 20 (hereinafter referred to as an intake manifold) is provided upstream of the injector 18 in the intake air flow. The intake manifold 20 is provided with a surge tank 21 for temporarily storing air flowing toward the intake port 11 side. The intake manifold 20 on the downstream side of the surge tank 21 is formed to branch toward the intake ports 11 of the plurality of cylinders, and the surge tank 21 is located at the branch point. The surge tank 21 functions to alleviate intake pulsation and intake interference that can occur in each cylinder.

A throttle body 22 is connected to the upstream side of the intake manifold 20. An electronically controlled throttle valve 23 is built in the throttle body 22, and the amount of air flowing to the intake manifold 20 is adjusted according to the opening (throttle opening θ _TH ) of the throttle valve 23. The throttle opening θ _TH is electronically controlled by the engine control device 1.
An intake passage 24 is connected further upstream of the throttle body 22. An air filter 25 is interposed further upstream of the intake passage 24. Thus, fresh air filtered by the air filter 25 is supplied to the cylinder of the engine 10 via the intake passage 24 and the intake manifold 20.

[1-4. Detection system]
At an arbitrary position of the vehicle, there is an accelerator stroke sensor 31 that detects the amount of depression of the accelerator pedal (accelerator operation amount A _PS ), and a brake fluid pressure sensor 33 that detects the brake fluid pressure _BRK corresponding to the brake operation amount. Provided. The accelerator operation amount A _PS is a parameter corresponding to the driver's acceleration request and intention to start, in other words, a parameter correlated to the load of the engine 10 (output request to the engine 10). Further, the brake hydraulic pressure B _RK during normal vehicle travel is a parameter corresponding to a driver's stop request and a parameter corresponding to a start request when the vehicle starts creeping. Information on the accelerator operation amount A _PS and the brake fluid pressure B _RK detected by these sensors 31 and 33 is transmitted to the engine control device 1.

A shift position sensor 32 (shift range detecting means) is attached to the select lever of the AT unit 26. The shift position sensor 32 is a sensor that detects the operation position of the select lever and outputs a range signal R _NG of the shift range corresponding to this. Here, it is detected which position of the P range, R range, N range, and D range the select lever is operated, and a range signal R _NG corresponding to each operation position is transmitted to the engine control device 1.

The intake passage 24, an air flow sensor 34 (flow rate detecting means) is provided for detecting the intake air flow rate Q _IN. The intake air flow rate Q _IN is a parameter corresponding to the actual air flow rate passing through the throttle valve 23. Since the intake air flow from the throttle valve 23 to the cylinder has a so-called intake air delay (a delay caused by flow resistance or intake inertia), the flow rate of air introduced into the cylinder at a certain time passes through the throttle valve 23 at that time. It does not necessarily match the flow rate of the air to be used. On the other hand, in the engine control apparatus 1 of the present embodiment, the intake air amount control is performed in consideration of such an intake air delay. Information about the intake air flow rate Q _IN detected by the air flow sensor 34 is transmitted to the engine control device 1.

A cooling water temperature sensor 35 for detecting the temperature of the engine cooling water (cooling water temperature W _TS ) is provided at an arbitrary position on the water jacket 19 or the cooling water circulation path. Note that the no-load loss of the engine 10 (such as mechanical loss inherent in the engine 10 itself) increases as the temperature of the engine 10 itself becomes lower, such as during cold start. The temperature of the engine 10 itself is reflected in the cooling water temperature W _TS of the water jacket 19. In this embodiment, it is assumed that the use of cooling water temperature W _TS as an index for estimating the no-load losses of the engine 10. Information of the cooling water temperature W _TS detected by the coolant temperature sensor 35 is transmitted to the engine control device 1.

The crankshaft 17, the engine rotational speed sensor 36 for detecting the rotation angle theta _CR is provided. The amount of change (angular speed ω) per unit time of the rotational angle θ _CR is proportional to the actual rotational speed Ne (actual rotational speed per unit time) of the engine 10. Therefore, the engine rotation speed sensor 36 has a function of acquiring the actual rotation speed Ne of the engine 10. Information about the actual rotational speed Ne acquired here is transmitted to the engine control device 1. The actual rotational speed Ne may be calculated inside the engine control device 1 based on the rotational angle θ _CR detected by the engine rotational speed sensor 36.

An intake manifold pressure sensor 37 that detects an actual intake manifold pressure P _IM (an intake manifold pressure corresponding to the pressure in the surge tank 21) is provided in the surge tank 21. Further, an atmospheric pressure sensor 38 for detecting the atmospheric pressure P _BP and an outside air temperature sensor 39 for detecting the outside air temperature AT are provided inside the engine control device 1 or at an arbitrary position of the vehicle. Each information of the actual intake manifold pressure P _IM , the atmospheric pressure P _BP and the outside air temperature AT acquired here is transmitted to the engine control device 1.

Incidentally, the atmospheric pressure P _BP can be handled as a pressure in the intake passage 24 inlet (pressure upstream of the air filter 25). Therefore, it is also possible to estimate the upstream pressure P _THU of the throttle valve 23 based on the atmospheric pressure P _BP (pressure in the intake passage 24 upstream of the throttle valve 23). For example, the intake system pressure loss value from the intake passage inlet to the throttle valve 23 corresponding to the actual rotational speed Ne of the engine 10 and the intake flow rate Q _IN is stored in the engine control device 1 in advance, and the intake system pressure loss from the atmospheric pressure P _{BP is} stored. By subtracting the value, the upstream pressure P _THU of the throttle valve 23 can be obtained. These atmospheric pressure P _BP and actual intake manifold pressure P _IM are used for calculation of a volume efficiency coefficient K _MAP that is an evaluation index of the intake performance according to the volume efficiency of the engine 10.

[1-5. Control system]
In addition to an engine control device 1 (Engine Electronic Control Unit), this vehicle is provided with a transmission ECU 51, an air conditioner ECU 52, an electrical component ECU 53, and the like as electronic control devices. These electronic control devices are configured, for example, as LSI devices or embedded electronic devices in which a microprocessor, ROM, RAM, and the like are integrated, and are connected to each other via a communication line of an in-vehicle network provided in the vehicle.

  The transmission ECU 51 controls the speed change operation of the AT unit 26, and the air conditioner ECU 52 controls the operation of an air conditioner (not shown). The electrical component ECU 53 controls the operation of various body-related electrical components such as an in-vehicle projector, various lighting devices, a power steering device, a power window device, and a door locking device. These various devices serve as loads on the engine 10.

Hereinafter, electronic control devices other than the engine control device 1 are also called external control systems, and devices controlled by the external control system are also called external load devices. The operating state or the like of the external load device can change regardless of the operating state of the engine 10. Therefore, each external control system described above calculates the magnitude of torque required by the external load device from the engine 10 as needed, and transmits this to the engine control device 1. The torques required by the respective external control systems for the engine 10 are referred to as external required torques E _XT1 , E _XT2 , E _XT3 . The value of the external demand torque E _XT1, E _XT2, E _XT3 is transmission ECU 51, air conditioning ECU 52, it may be transmitted to the engine control device 1 after being calculated in each of the external control system such as electrical components ECU53 Alternatively, it may be calculated by the engine control device 1 based on information collected by each external control system.

The engine control device 1 is an electronic control device that controls a wide range of systems such as an ignition system, a fuel system, an intake / exhaust system, and a valve system related to the engine 10. The amount of air supplied to each cylinder of the engine 10, fuel It controls the injection amount and ignition timing. Here, torque base control based on the magnitude of torque required for the engine 10 is performed. Specific control objects of the engine control device 1 include the amount of fuel injected from the injector 18 and the injection timing, the ignition timing at the spark plug 13, the throttle opening θ _TH of the throttle valve 23, and the like.

  In the torque base control of the present embodiment, three types of required torque are assumed as the torque required for the engine 10. The first required torque corresponds to the driver's acceleration request, and the second required torque corresponds to the request from the external load device. Both of these required torques can be said to be torques calculated based on the load acting on the engine 10. On the other hand, the third required torque is for idle feedback control (idle control) for maintaining the actual rotational speed Ne of the engine 10 at the idle rotational speed, and in a no-load state in which no load is applied to the engine 10. Even if there is, it is a required torque to be considered. The engine control device 1 calculates a target torque, which is a target value of the torque that the engine 10 should output, while automatically switching the above three types of required torque according to the operating conditions of the engine 10, and the target torque is The fuel amount, injection timing, intake air amount, ignition timing, etc. are controlled so as to be obtained.

In the engine control device 1, automatic stop control (idle stop control) and restart control for automatically stopping and restarting the engine 10 according to the running state of the vehicle are performed. The automatic stop control here refers to the automatic stop of the engine 10 with the operation position of the ignition key switch maintained in the ON position when a predetermined automatic stop condition is satisfied during the operation of the engine 10. Control. The restart control is a control for automatically restarting the engine 10 when a predetermined restart condition is satisfied while the engine 10 is stopped by the automatic stop control.
Hereinafter, among the controls performed by the engine control apparatus 1, the control at the start and restart of the engine 10 will be described.

[2. Control configuration]
As shown in FIG. 1, the above-described various sensors, an in-vehicle communication network, and other electronic control devices are connected to the input side of the engine control device 1. Further, an ignition plug 13, an injector 18, a throttle valve 23, and the like, which are control targets for torque base control, are connected to the output side of the engine control device 1.

  The engine control apparatus 1 includes an idle stop control unit 2, a required torque calculation unit 3, a torque upper limit calculation unit 4, a target torque calculation unit 5, a starting throttle opening restriction unit 6, and an opening restriction release unit 7. It is done. The function of each of these elements may be realized by an electronic circuit (hardware), may be programmed as software, or a part of these functions may be provided as hardware, and other parts may be provided. Software may be used.

[2-1. Idle stop control unit]
The idle stop control unit 2 determines conditions relating to automatic stop control and restart control and performs these controls. The automatic stop condition is satisfied when, for example, all of the following conditions 1 to 5 are satisfied. In general automatic stop control, automatic stop control is started when a predetermined idle stop condition is satisfied in a state where a predetermined idle operation condition regarding at least the vehicle speed and the accelerator operation amount _APS is satisfied.

The automatic stop control of the present embodiment is the same, and among the following conditions 1 to 5, conditions 1, 3, and 5 are each one of idle operation conditions (conditions for determining that the engine is idling). is there.
Condition 1: The operation position is the P range, the N range, or the D range. Condition 2: The cooling water temperature W _TS is equal to or higher than a predetermined temperature (the engine 10 has been warmed up).
Condition 3: Accelerator operation amount A _PS is 0 (no accelerator pedal depression)
Condition 4: Brake fluid pressure B _RK is greater than or equal to a predetermined value (with brake pedal depressed)
Condition 5: The vehicle is stopped (the vehicle speed is 0).

Further, the restart condition is, for example, that any of the following conditions 6 to 10 is satisfied.
Condition 6: The operation position is in the R range Condition 7: The accelerator operation amount A _PS is not 0 (the accelerator pedal is depressed)
Condition 8: Brake hydraulic pressure B _RK is less than a predetermined value (with brake pedal depressed)
Condition 9: The vehicle is not stopped (the vehicle speed is not 0)
Condition 10: A start request from an external load device has occurred

As specific examples of the above condition 10, when the battery charge amount, the battery voltage, etc. during the automatic stop are reduced, the electric power required by the electrical components cannot be secured (when power generation is required), or the air conditioner device For example, when it is necessary to start the engine 10 to drive the compressor. That is, depending on a request for an external load, restart control of the engine 10 is performed even if the conditions 6 to 9 are not satisfied. Therefore, the range position when the engine 10 is restarted is not necessarily the R range defined in the condition 6, and may be restarted in the N range or the D range. Further, regarding the magnitude of the accelerator operation amount A _{PS and} the magnitude of the brake fluid pressure B _RK , all values can be taken when the engine 10 is restarted.

  When the automatic stop condition is satisfied, the idle stop control unit 2 performs automatic stop control, and stops the engine 10 by controlling the injector 18 to stop the fuel supply, for example. On the other hand, when the restart condition is satisfied during the automatic stop of the engine 10 by the automatic stop control, the idle stop control unit 2 performs the restart control, for example, drives a cell motor (not shown) and starts fuel supply, thereby 10 is restarted.

[2-2. Required torque calculation unit]
The required torque calculation unit 3 aggregates the torque required from the external control system such as the transmission ECU 51, the air conditioner ECU 52, and the electrical component ECU 53 and the torque required by the driver, and sets the required torque for the engine 10. It is. Here, four types of required torques are calculated: idle request torque _{Pi_NeFB} , accelerator request torque _{Pi_APS} , ignition control request torque _{Pi_EXT_SA} , and intake control request torque _{Pi_EXT} .

The idle request torque _{Pi_NeFB} is a torque mainly required for maintaining the operation state of the engine 10 in the idle operation state. Further, the accelerator required torque _{Pi_APS} is a torque mainly requested by the driver during normal operation of the vehicle. Here, the ignition control required torque _{Pi_EXT_SA} and the intake control required torque _{Pi_EXT} are calculated based on the accelerator required torque _{Pi_APS} .

The ignition control required torque _{Pi_EXT_SA} is torque used in ignition control (ignition timing control) of the spark plug 13. The ignition control is a highly responsive control with a short time lag from when the control is actually performed until the torque is generated in the engine 10. However, the range of torque that can be adjusted by ignition control is relatively small.
On the other hand, the required torque for intake control _{Pi_EXT} is a torque used in intake control (control of intake air amount) of the throttle valve 23. The intake control is a control in which the time lag from when the control is actually performed until the torque is generated in the engine 10 is long, and the response is slightly inferior to the ignition control. However, the range of torque that can be adjusted by intake control is larger than that by ignition control.

  The calculation process in the required torque calculation unit 3 is illustrated in FIG. The required torque calculation unit 3 includes a target idle speed setting unit 3a, an idle request torque calculation unit 3b, an accelerator request torque calculation unit 3c, and an external request torque calculation unit 3d.

The target idle rotation speed setting unit 3a (second setting means) sets a target rotation speed when the engine 10 is in an idle operation state as a target idle rotation speed Ne _OBJ (so-called target idle rotation speed). An idle operation state is that operational state idling condition is satisfied, is determined in accordance with the vehicle speed and accelerator operation amount A _PS like. The idling operation condition includes, for example, the above condition 1, condition 3, and condition 5.

The target idle rotation speed setting unit 3a sets the target idle rotation speed Ne _OBJ according to the coolant temperature _WTS and the operation position of the select lever. Here, for example, the target idle rotation speed Ne _OBJ when the operation position is the D range and the R range is set to be smaller than the target idle rotation speed Ne _OBJ when the operation position is the P range and the N range. Further, the target idle speed Ne _OBJ is set smaller as the coolant temperature _WTS is higher. In addition, it is good also as a structure which changes the magnitude _| size of target idle rotational speed NeOBJ according to the operating state of an external load apparatus. The information of the target idle rotation speed Ne _OBJ calculated here is transmitted to the idle request torque calculator 3b and the torque upper limit calculator 4.

The idle request torque calculation unit 3b calculates a torque corresponding to the set target idle rotation speed Ne _OBJ (torque required to maintain the actual rotation speed Ne at the target idle rotation speed Ne _OBJ ) as the idle request torque _{Pi_NeFB} . Is. The idle request torque _{Pi_NeFB} calculated here is _transmitted to the external request torque calculation unit 3d and the target torque calculation unit 5.

The accelerator request torque calculator 3c calculates the torque required for the engine 10 by the driver's accelerator operation as the accelerator request torque _{Pi_APS} . Here, the accelerator demanded torque Pi _{_APS} is calculated on the basis of the actual rotational speed Ne and the accelerator operation amount A _PS. Note that the magnitude of the accelerator required torque _{Pi_APS} may be changed according to the operating state of the external load device. The information of the accelerator required torque _{Pi_APS} calculated here is transmitted to the external required torque calculation unit 3d and the target torque calculation unit 5.

External request torque calculating unit 3d is the accelerator demanded torque Pi _{_APS} calculated in the accelerator required torque calculating unit 3c as a base, a torque request from an external load device to be transmitted from the external control system _{(E XT1, E XT2, E} XT3 ) And the like are calculated. The first required torque is the ignition control required torque _{Pi_EXT_SA} , and the second required torque is the intake control required torque _{Pi_EXT} . The ignition control required torque _{Pi_EXT_SA} and the intake control required torque _{Pi_EXT} are calculated in the external required torque calculation unit 3d independently of each other. Each of the required torques calculated here is transmitted to the target torque calculator 5.

[2-3. Torque upper limit calculation unit]
The torque upper value calculation unit 4 calculates an upper limit torque Pi _{LIM_H} when the engine 10 is started. Here, when the engine 10 is started, it means a manual start or a restart by restart control, and a period until the actual rotational speed Ne converges to the target idle rotational speed Ne _OBJ after the engine 10 is completely exploded. Is included.

In general, the actual rotational speed Ne of the engine 10 is controlled so as to converge to the target idle rotational speed Ne _OBJ after rapidly increasing after the complete explosion of the engine 10. The increase in the actual rotational speed Ne after the complete explosion is called “swelling”. The torque upper limit calculation unit 4 sets the upper limit torque Pi as the maximum value of the torque for making the racing as small as possible (so that the actual rotational speed Ne does not increase excessively) within a range that does not impede the startability of the engine 10. _{Calculate LIM_H} . _Further , the control for limiting the engine torque with the upper limit torque Pi _{LIM_H} is referred to as upper limit control.

Since the upper limit control is a control that functions to suppress an increase in the engine torque, for example, if the value of the upper limit torque Pi _{LIM_H} is set as a fixed value, the startability is lowered depending on the operating condition of the engine 10. There is a fear. On the other hand, in the torque upper limit control of the present embodiment, the startability is improved by setting the value of the upper limit torque Pi _{LIM_H} as needed according to the driver's intention to start when the engine 10 is started and the operation position of the select lever. While ensuring, it prevents blowing up.

  The calculation process in the torque upper limit calculation unit 4 is illustrated in FIG. The torque upper limit calculation unit 4 includes a rotation speed upper limit setting unit 4a, an offset amount setting unit 4b, a rotation speed difference calculation unit 4c, an upper limit gradient calculation unit 4d, an actual change rate calculation unit 4e, a gradient difference calculation unit 4f, a torque A correction amount calculation unit 4g, an actual torque calculation unit 4h, an upper limit torque calculation unit 4k, and a condition determination unit 4m are provided.

The rotation speed upper limit value setting unit 4a (first setting means) sets an upper limit rotation speed Ne _{LIM_H} (upper rotation speed per unit time) that is an upper limit value of the actual rotation speed Ne. Here, based on various parameters related to the driving state of the vehicle, a plurality of upper limit rotational speeds Ne _{LIM_H} are calculated, and an appropriate upper limit rotational speed Ne _{LIM_H} is selected according to the driving state from among them. . The final upper limit rotation speed Ne _{LIM_H} selected here is transmitted to the rotation speed difference calculation unit 4c.

FIG. 4 schematically shows a method for setting the upper limit rotational speed Ne _{LIM_H} . The rotation speed upper limit value setting unit 4a sets an upper limit rotation speed Ne _{LIM_H} for each of the accelerator operation amount A _PS , the brake fluid pressure B _RK , and the coolant temperature W _TS , and sets these upper limit rotation speed Ne _{LIM_H} and the target idle rotation speed. Based on Ne _OBJ , the final upper limit rotational speed Ne _{LIM_H} is set. As shown in FIG. 4, the rotation speed upper limit value setting unit 4a is provided with a first upper limit value setting unit 41, a second upper limit value setting unit 42, and a third upper limit value setting unit 43, and two maximum values. Selection units 44 and 45 and one minimum value selection unit 46 are provided. Hereinafter, the upper limit values set by the setting units 41 to 43 are referred to as first upper limit value to third upper limit value, and the upper limit values selected by the two maximum value selection units 44 and 45 are the first. It is called the fourth upper limit and the fifth upper limit.

The first upper limit setting unit 41 sets the first upper limit based on the brake fluid pressure _BRK . Here, as shown in FIG. 5 (c), characteristics such as the upper limit rotational speed Ne _{LIM_H} larger the brake fluid pressure B _RK is lowered map is set in advance in a formula or the like. The first upper limit setting unit 41 sets the first upper limit value using these maps, mathematical expressions, and the like, and controls the intention to start when the brake is operated (the intention to start when the brake pedal depression operation is weakened). To reflect.

Incidentally, the two-dot chain line shown in FIG. 5 (c) is a line indicating the target idle rotational speed Ne _OBJ at Yutakatai. The first upper limit value is set in a range equal to or higher than the target idle rotation speed Ne _OBJ at the time of warm. However, since the target idle speed Ne _OBJ at the time of cold start is set higher than that at the time of warm, the two-dot chain line in the figure moves upward on the graph. Therefore, if a time cold start is relatively large brake fluid pressure B _RK may sometimes first upper limit is below the target idle rotational speed Ne _OBJ.

On the other hand, the first upper limit value set by the first upper limit value setting unit 41 is input to the maximum value selection unit 44 together with the target idle speed Ne _OBJ , and one of these is selected as the fourth upper limit value. Is done. Accordingly, the fourth upper limit will be increased at the target idling rotational speed Ne _OBJ above range as the brake fluid pressure B _RK is small. The fourth upper limit value never falls below the target idle rotation speed Ne _OBJ , that is, at least the target idle rotation speed Ne _OBJ is ensured no matter how strongly the actual rotation speed Ne is limited.

The second upper limit setting unit 42 sets a second upper limit based on the accelerator operation amount _APS . Here, as shown in FIG. 5A, characteristics such that the upper limit rotational speed Ne _{LIM_H} increases as the accelerator operation amount A _PS increases are preset by a map, a mathematical expression, or the like. The second upper limit value setting unit 42 sets the second upper limit value using these maps, mathematical expressions, and the like, and reflects the intention to start at the time of accelerator operation in the upper limit value control. Incidentally, the two-dot chain line shown in FIG. 5 (a) is a line indicating the target idle rotational speed Ne _OBJ at Yutakatai. Similar to the first upper limit value, the second upper limit value is set in a range equal to or higher than the target idle rotation speed Ne _OBJ during the warm state.
Further, when the operation position of the select lever is the D range, the second upper limit value is set smaller than when the select lever is other than the D range (P range, R range, N range). The second upper limit value set here is input to the maximum value selection unit 45.

The third upper limit setting unit 43 sets the third upper limit based on the coolant temperature _WTS . Here, as shown in FIG. 5 (b), properties such as higher cooling water temperature W _TS upper limit rotation speed Ne _{LIM_H} (third upper limit) is lowered map is set in advance in a formula or the like. The third upper limit value setting unit 43 sets a third upper limit value using these maps, mathematical expressions, and the like, and reflects the degree of warm-up of the engine 10 in the upper limit value control. 5B is a line indicating the target idle rotation speed Ne _OBJ , and the third upper limit value is set in a range equal to or higher than the target idle rotation speed Ne _OBJ . The target idle speed Ne _OBJ is generally set lower as the cooling water temperature W _TS is higher, and the engine friction is reduced and the engine startability is slightly improved, so the upper limit control is applied slightly stronger. Effectively suppresses overshoot.

Similarly to the second upper limit value, the third upper limit value is set to be smaller when the operation position of the select lever is the D range than when it is other than the D range (P range, R range, N range). . The third upper limit value set here is input to the maximum value selection unit 45.
As described above, one maximum value selection unit 44 selects one of the first upper limit value and the target idle rotation speed Ne _OBJ as the fourth upper limit value, and the other maximum value selection unit. 45 is for selecting the larger one of the second upper limit value and the third upper limit value as the fifth upper limit value.

The fourth upper limit value is a parameter that works so as to increase the upper limit value control as the brake operation amount is larger (the brake pedal is depressed more), and at least the target idle speed Ne _OBJ is maintained. is there.
The fifth upper limit value is a parameter that works to increase the upper limit control as the accelerator operation is smaller (the accelerator pedal is depressed more) or as the cooling water temperature _WTS is higher. Since the second upper limit value and the third upper limit value are set in a range equal to or higher than the target idle rotation speed Ne _OBJ , the fifth upper limit value is also equal to or higher than the target idle rotation speed Ne _OBJ . Therefore, both the fourth upper limit value and the fifth upper limit value are set in a range equal to or higher than the target idle speed Ne _OBJ . These fourth upper limit value and fifth upper limit value are input to the minimum value selection unit 46.

The minimum value selection unit 46 selects the smaller one of the fourth upper limit value and the fifth upper limit value as the final upper limit rotation speed Ne _{LIM_H} . Here, one of the control amount derived from the brake operation and the operation amount derived from the accelerator operation is selected which is strongly restricted. For example, when there is no brake operation, the first upper limit value corresponding to the brake fluid pressure B _RK is set to be large (a weak limit) assuming that there is a willingness to travel, so the second corresponding to the accelerator operation amount A _PS The limit is added by the third upper limit value corresponding to the upper limit value or the cooling water temperature _WTS . On the other hand, the first upper limit (a strong restrictions) to set the smaller as the running intent is low when there is a brake operation for the lower limit rotation speed Ne _{LIM_H} than the second upper limit value and the third upper limit Can be selected, ie, more restrictive can be added.

Offset amount setting section 4b (offset amount setting means) is for setting the offset amount? Ne _OFS actual rotation speed Ne based on the cooling water temperature W _TS. The offset amount ΔNe _OFS is an amount related to a condition for starting the upper limit control for limiting the engine torque by using the upper limit torque Pi _{LIM_H} , and includes the fluctuation range of the actual rotational speed Ne for performing the upper limit control. Correspond. That is, in the upper limit control, the actual rotational speed Ne is controlled within the range of (Ne _{LIM_H−} ΔNe _OFS ) ≦ Ne (and so that Ne <Ne _{LIM_H} can continue to be _satisfied ). Therefore, when the actual rotational speed Ne is less than (Ne _{LIM_H−} ΔNe _OFS ) immediately after the engine 10 is started, the upper limit value control is not performed, and the actual rotational speed Ne becomes (Ne _{LIM_H−} ΔNe _OFS ) or more. Upper limit control is started from the time point.

Here, for example, as shown in FIG. 5 (d), the value as the cooling water temperature W _TS is lower as the offset amount? Ne _OFS increase is set. As the offset amount ΔNe _OFS is larger, the upper limit control is more easily started after the engine is started (the time from the start time of the engine 10 until the upper limit control is started is shorter), and the actual rotational speed Ne is relatively low. A torque limit will be added in stages. However, when starting at an extremely low cooling water temperature _WTS at an extremely low temperature, the offset amount ΔNe _OFS may be slightly reduced by giving priority to improving the startability. Information of the offset amount ΔNe _OFS set here is transmitted to the condition determination unit 4m.

The rotational speed difference calculation unit 4 c calculates a rotational speed difference ΔNe between the upper limit rotational speed Ne _{LIM_H} set by the rotational speed upper limit value setting unit 4 a and the actual rotational speed Ne of the engine 10. This rotational speed difference ΔNe is a value _obtained by subtracting the upper limit rotational speed Ne _{LIM_H} from the actual rotational speed Ne, and ΔNe = Ne−Ne _{LIM_H} . The rotation speed difference ΔNe calculated here is transmitted to the upper limit gradient calculation unit 4d.

The upper limit gradient calculating unit 4d (upper gradient calculating means), based on the rotational speed difference? Ne, is intended for calculating the upper limit gradient dNe _{_H} of the rate of change of actual rotational speed Ne (the upper limit acceleration of the actual rotational speed Ne). The upper limit gradient calculating unit 4d, for example, as shown in FIG. 5 (e), the correspondence relationship between the rotational speed difference ΔNe and upper slope dNe _{_H} is preset in a formula or a map or the like, such correspondence calculating an upper limit gradient dNe _{_H} used. The value of the upper slope dNe _{_H} computed here, is transmitted to the gradient difference calculation section 4f.

Upper gradient dNe _{_H,} the actual rotation speed Ne corresponds to the amount of change may maximum change until the elapse of the predetermined unit time from that point, i.e. corresponding to the maximum value of the future change gradient. In the example shown in FIG. 5 (e), the upper limit gradient dNe _{_H} when the rotational speed difference ΔNe is negative is a positive value, the upper limit gradient dNe _{_H} when the rotational speed difference ΔNe is positive is a negative value. That is, when the actual rotational speed Ne is smaller than the upper limit rotation speed Ne _{LIM_H} would its variation gradient such that the actual rotational speed Ne closer to the upper limit rotational speed Ne _{LIM_H} is less likely to increase more approaches zero. Further, when the actual rotational speed Ne exceeds the upper limit rotational speed Ne _{LIM_H} , the change gradient becomes negative (decreasing gradient) so that the actual rotational speed Ne is likely to decrease. Thus, the upper limit gradient dNe _{_H} is steep larger absolute value of the rotational speed difference ΔNe is, with the graph characteristics closer as horizontal smaller absolute value of the rotational speed difference ΔNe is. That is, the target value of the rate of change dNe of the actual rotational speed Ne decreases as the absolute value of the rotational speed difference ΔNe increases.

The actual change rate calculation unit 4e calculates the change rate of the actual rotational speed Ne of the engine 10 as an actual change rate dNe (actual acceleration). The actual change rate dNe corresponds to the actual change gradient of the actual rotational speed Ne up to that point. Maximum In other words, the actual rate of change dNe from past while corresponding to the change gradient of the up to now, the upper limit gradient dNe _{_H} corresponds to the maximum value of the gradient of change from present to future, ie the gradient of change as the control target Corresponds to the value.

Here, based on the actual rotational speed Ne _(n) detected in the stroke and the actual rotational speed Ne _(nk) detected at the time before the k stroke, the actual change rate dNe is calculated according to the following equation 1, for example. The The actual change rate dNe calculated here is transmitted to the gradient difference calculation unit 4f and the condition determination unit 4m. In this embodiment, k = 2, that is, the change gradient of the actual rotational speed Ne in the period from the time point two strokes before to the present is calculated.

The gradient difference calculation section 4f (gradient difference calculating means), and upper slope dNe _{_H} calculated by the upper limit gradient calculating unit 4d, the difference gradient difference ΔdNe between the actual rate of change dNe calculated by actual change rate arithmetic unit 4e ( (Acceleration difference). The gradient difference ΔdNe is given by the following equation 2, for example. Information of the gradient difference ΔdNe calculated here is transmitted to the torque correction amount calculation unit 4g.

Torque correction amount computing unit 4g is for calculating the torque correction value Pi _{DNe_H} required to so change gradient future actual rotational speed Ne does not exceed the upper limit gradient dNe _{_H.} This torque correction value Pi _{dNe_H} is obtained by converting the gradient difference ΔdNe calculated by the gradient difference calculation unit 4f into a torque value. Here, based on the moment of inertia Ie around the crankshaft of the engine 10, the cylinder volume V _ENG and the gradient difference ΔdNe, the torque correction value _{PidNe_H} is calculated according to the following equation 3. The torque correction value _{PidNe_H} calculated here is transmitted to the upper limit torque calculation unit 4k.

Actual torque calculation section 4h is for calculating on the basis of the intake air flow rate Q _IN detected by the air flow sensor 34, the torque may occur in the actual intake air amount introduced into the cylinder as the actual torque Pi _ACT. The actual torque Pi _ACT is an estimated value of torque generated when an amount of air corresponding to the intake flow rate Q _IN is burned at a predetermined air-fuel ratio. In the present embodiment, the actual torque Pi _ACT before the second _stroke is calculated in accordance with the period related to the calculation of the change gradient in the actual change rate calculation unit 4e. Here actual torque Pi _ACT calculated at is transmitted to the upper limit torque calculating section 4k.

The upper limit torque calculator 4k calculates the upper limit torque Pi _{LIM_H} based on the actual torque Pi _ACT before the second _stroke calculated by the actual torque calculator 4h and the torque correction value Pi _{dNe_H} calculated by the torque correction amount calculator 4g. It is to calculate. The upper limit torque Pi _{LIM_H} is a parameter for limiting the maximum value of torque required for the engine 10. Here, the value _obtained by subtracting the torque correction value Pi _{dNe_H} from the actual torque Pi _ACT before the second _stroke is calculated as the upper limit torque Pi _{LIM_H} . That is, Pi _{LIM_H} = (Pi _ACT before the second _stroke ) _{−PidNe_H} .

Note that the maximum value of the torque limited by the upper limit control may be set in advance as the fully open torque Pi _MAX , and the range that the upper limit torque Pi _{LIM_H} can take may be limited to a range equal to or less than the fully open torque Pi _MAX . For example, a smaller one of the upper limit torque Pi _{LIM_H} calculated here and a predetermined full-open torque Pi _MAX may be selected and used as the final upper limit torque Pi _{LIM_H} . The upper limit torque Pi _{LIM_H} calculated here is transmitted to the condition determination unit 4m.

The condition determination unit 4m determines the start condition and the end condition of the upper limit control that limits the engine torque using the upper limit torque Pi _{LIM_H} calculated by the upper limit torque calculation unit 4k. The starting condition for the upper limit control is that all of the following conditions 11 to 13 are satisfied. For example, when restarting from an idle stop state or when starting the engine 10 by manual operation (ignition key operation), these conditions are determined, and when all the conditions are satisfied, information on the upper limit torque Pi _{LIM_H} is obtained as a condition determination unit. 4 m is transmitted to the target torque calculator 5.

Condition 11: The actual rotational speed Ne is higher than a predetermined start completion determination rotational speed Ne _S
Large (Ne> Ne _S )
Condition 12: The actual rotational speed Ne is _set to the offset amount ΔNe _OFS from the upper limit rotational speed Ne _{LIM_H.}
Exceeded value (Ne> Ne _{LIM_H} -ΔNe _OFS )
Condition 13: Restriction target torque Pi _{BS_LIM} is set to the torque correction value Pi _{dNe_H} .
Exceeded (Pi _{BS_LIM} > Pi _{dNe_H} )

Incidentally, restricted torque Pi _{BS_LIM} conditions 13, required torque calculating unit 3 with the calculated accelerator demanded torque Pi _{_APS} and ignition control torque demand Pi _{_EXT_SA,} among actual torque Pi _ACT like in its travel, the largest torque Is the torque corresponding to.
Further, the end condition of the upper limit control is that any of the following conditions 14 to 17 is satisfied. For example, if any of these conditions is satisfied during the execution of the limit control, the information transmission of the upper limit torque Pi _{LIM_H} from the condition determination unit 4m to the target torque calculation unit 5 is interrupted, and the upper limit value control ends.

Condition 14: conditions idle feedback control is performed 15: Conditions elapsed time after the engine start exceeds a predetermined time limit 16: the estimated value of the filter value and the in-cylinder intake air amount of the intake air flow rate Q _IN substantially coincide Condition 17: The actual change rate dNe of the actual rotational speed Ne is 0 or less.

The above condition 16 is that the estimated value of the in-cylinder intake air amount actually introduced into the cylinder and the filter value of the intake air flow rate Q _IN detected by the air flow sensor 34 (the intake air delay between the air flow sensor 34 and the cylinder). Is the condition that the upper limit control is terminated.

Generally, immediately after the start of the engine 10, the actual intake manifold pressure P _IM for approximately has the state close to the atmospheric pressure P _BP, intake air flow rate Q _IN large amount of air than is temporarily detected by the air flow sensor 34 It flows into the cylinder. In other words, the actual in-cylinder intake air amount immediately after starting is larger than the intake air amount corresponding to the intake air flow rate Q _IN detected by the air flow sensor 34, and the engine speed is likely to increase. On the other hand, when the actual intake manifold pressure P _IM over time is lowered gradually become the intake air amount corresponding to the intake flow rate Q _IN-cylinder intake air amount matches the operating conditions have stabilized.

  6A and 6B illustrate a change in the in-cylinder intake air amount at the start of the engine 10 and a change in the intake air amount based on the detection value by the air flow sensor 34. FIG. The broken line in the figure is the air amount corresponding to the detection value (raw value) of the air flow sensor 34, and the thin solid line is the intake amount (filter value) obtained by filtering the raw value for the intake air delay. The thick solid line is an estimated value of the in-cylinder intake air amount.

The initial value of the cylinder intake air amount, the actual intake manifold pressure P _IM is the atmospheric pressure P _BP throttle valve 23 corresponds to the intake air amount at the time of full opening, for example, set in advance from the volume or the like of the surge tank 21 and the intake passage 24 Can be kept. Further, the variation in the in-cylinder intake air amount can be approximated by a first-order lag with respect to the value detected by the air flow sensor 34. Therefore, for example, as shown in FIG. 6 (a), an estimated value of the actual in-cylinder intake air amount and an intake air amount that conforms to the sensor detection value are calculated at any time until the difference between the two becomes less than a predetermined value (almost) By setting the period until the coincidence) as the execution period of the upper limit control, the racing is effectively suppressed.

  Such setting of the implementation period can be applied even when an accelerator operation is performed during the upper limit control. That is, as shown in FIG. 6 (b), when the detected value (broken line) in the air flow sensor 34 increases as the accelerator operation amount increases, the estimated intake air amount (thin solid line) follows the fluctuation with a delay. To change. On the other hand, the in-cylinder intake air amount (thick solid line) is also approximated by a first-order lag with respect to the detected value (broken line), and the value of the in-cylinder intake air amount and the estimated intake amount gradually approaches.

  6 (a) and 6 (b), the time taken for the in-cylinder intake air amount to substantially coincide with the estimated intake air amount is shortened when the accelerator is operated compared to when the accelerator is not operated. I understand. This is because the engine speed increases due to the accelerator operation, and the number of intakes increases. However, when the operation position of the select lever is in the non-traveling range, even if the upper limit control is terminated when the above condition 16 is satisfied, the engine speed is sufficiently prevented from rising. Further, even if the operation position of the select lever is in the travel range, it is possible to obtain a blow-up suppression effect. However, if necessary, the upper limit value control period is extended as compared to when the above condition 16 is satisfied. May be.

[2-4. Target torque calculation unit]
The target torque calculator 5 (upper limit control means, idle control means) is based on the various required torques calculated by the required torque calculator 3 and the upper limit torque Pi _{LIM_H} calculated by the torque upper limit calculator 4. A target torque as a type of control target is calculated. Here, ignition control target torque _{Pi_TGT} and intake control target torque _{Pi_ETV_STD} are calculated. The throttle opening θ _TH of the throttle valve 23 and the fuel injection amount are controlled based on the intake control target torque Pi _{ETV_STD} calculated here. The ignition timing at the spark plug 13 is controlled based on the ignition control target torque _{Pi_TGT} calculated here.

  The calculation process in the target torque calculation unit 5 is illustrated in FIG. The target torque calculation unit 5 includes an intake selection unit 5a, an intake upper limit limiting unit 5b, an intake delay correction unit 5c, an ignition first upper limit limiting unit 5d, an ignition second upper limit limiting unit 5e, and an ignition target. A selection unit 5f is provided.

The intake selector 5a selects any one of the intake control required torque _{Pi_EXT} , the accelerator required torque _{Pi_APS,} and the idle required torque _{Pi_NeFB} as a target value of the intake control torque. Here, for example, the torque value is selected based on information such as the presence / absence of a torque request from the external control system and the necessity of idling operation of the engine 10. Here, the conditions for selecting the idle request torque _{Pi_NeFB} include the above-described conditions 1, 3, and 5. In the present embodiment, the idle request torque _{Pi_NeFB} is selected when the actual rotational speed Ne increases immediately after the engine 10 is started and the actual change rate dNe becomes zero. That is, the idle feedback control is performed from when the actual change rate dNe becomes 0 or less for the first time after the engine 10 is started. The torque value selected here is transmitted to the intake upper limit limiting unit 5b.

The intake upper limit value limiting unit 5b selects one of the torque value selected by the intake selection unit 5a and the upper limit torque Pi _{LIM_H} calculated by the torque upper value calculation unit 4. One of the torques selected here is transmitted to the intake air delay correction unit 5c. If the upper limit torque Pi _{LIM_H} is smaller than the torque value selected by the intake selector 5a, the upper limit torque Pi _{LIM_H} is preferentially selected, and thus the torque is limited. On the other hand, if the upper limit torque Pi _{LIM_H} is larger than the torque value selected by the intake selector 5a, the selected torque is transmitted as it is to the intake delay corrector 5c.

Note that, as described in the above condition 14, the upper limit control is not performed when the engine 10 is idling. Therefore, when the torque selected by the intake selector 5a is required idle torque Pi _{_NeFB} omits a comparison operation between the upper limit torque Pi _{LIM_H,} as intake delay correction unit an idle request torque Pi _{_NeFB} input You may transmit to 5c.

The intake air delay correcting unit 5c performs a correction operation according to the intake air delay with reference to the throttle valve 23. Here, based on the intake characteristics of the engine 10 and the throttle valve 23, the intake control target torque Pi _{ETV_STD} is calculated as a torque value taking into account the intake air delay. Various intake air delay calculation methods are conceivable depending on the control mode of the throttle valve 23 using the intake control target torque Pi _{ETV_STD} calculated here. For example, the torque value selected by the intake selector 5a is desired to be realized by performing a first-order lag process and a second-order lag process simulating an actual intake lag according to the operating condition and the type of requested torque selected. A locus of torque fluctuation may be generated.

The first upper limit value limiting unit for ignition 5d _selects one of the accelerator required torque _{Pi_APS} and the upper limit torque Pi _{LIM_H} , whichever is smaller. Similarly, the ignition second upper limit value limiting unit 5e selects one of the ignition control request torque _{Pi_EXT_SA} and the upper limit torque _{PiLIM_H} , whichever is smaller. These selected torques are transmitted to the ignition selector 5f.

The ignition selection unit 5f selects any one of the two selected torques and the idle required torque _{Pi_NeFB} as the ignition control target torque _{Pi_TGT} . Here, similarly to the selection by the intake selector 5a, the torque value is selected based on information such as whether or not there is a torque request from the external control system and whether or not the engine 10 is idling. In the ignition selection unit 5f of the present embodiment, the idle request torque _{Pi_NeFB} is selected when the actual change rate dNe becomes 0 immediately after the engine 10 is started, similarly to the intake selection unit 5a. ing.

In this way, in the engine control device 1, various output requests to the engine 10 are converted into torque and unified into the intake control target torque Pi _{ETV_STD} and the ignition control target torque _{Pi_TGT} . Further, based on the intake control target torque Pi _{ETV_STD} and the ignition control target torque _{Pi_TGT} , the engine control apparatus 1 uses the throttle valve θ _TH of the throttle valve 23, the fuel injection amount, the ignition timing at the spark plug 13, etc. Is controlled.

[2-5. Throttle opening limiter at start-up]
The starting throttle opening restriction unit 6 controls the opening of the throttle valve 23 based on the intake control target torque Pi _{ETV_STD} calculated by the target torque calculation unit 5. Here, separately from the upper limit control described above, the opening limit control is performed to limit the opening degree of the throttle opening _θTH . The opening limit control may be performed simultaneously (overlapping) with the above upper limit control, or may be performed exclusively. In the case of performing exclusively, it is preferable to prioritize the opening limit control over the upper limit control.

In the case of overlapping, control is performed to further limit the upper limit value for the intake control target torque Pi _{ETV_STD} output from the intake air delay correction unit 5c of the target torque calculation unit 5. In the case of exclusive implementation, the value of the upper limit torque Pi _{LIM_H} input to the intake upper limit value limiting unit 5b of the target torque calculating unit 5 is changed to zero, and the intake air output from the intake delay correcting unit 5c Control for limiting the upper limit value for the control target torque Pi _{ETV_STD} is performed.

As shown in FIG. 1, the starting throttle opening control unit 6 is provided with a target area calculation unit 6a (opening calculation means) and an upper limit area calculation unit 6b (limitation means). The target area calculation unit 6a calculates a target throttle area S (opening area of the throttle valve 23) corresponding to the intake control target torque Pi _{ETV_STD} . On the other hand, the upper limit area calculation unit 6b calculates an upper limit value S _LIM of the target throttle area S when the engine 10 is started.
As shown in FIG. 8, the target area calculation unit 6a includes a target air amount calculation unit 6c, a target in-cylinder air amount calculation unit 6d, an intake advance compensation unit 6e, a target flow rate calculation unit 6f, a flow velocity calculation unit 6g, and a throttle area. A calculation unit 6h is provided.

The target air amount calculation unit 6c (air amount calculation means) calculates the target charging efficiency Ec _TGT based on the actual rotational speed Ne and the standard condition intake target torque Pi _{ETV_STD} . The target charging efficiency Ec _TGT is the charging efficiency corresponding to the target air amount to be introduced into the cylinder to be controlled. The target air amount calculation unit 6c stores, for example, the relationship between the actual rotational speed Ne and the standard condition intake target torque Pi _{ETV_STD} and the target charging efficiency Ec _TGT as a map or a mathematical formula, and uses this to calculate the target charging efficiency Ec _TGT . calculate. The value of the target charging efficiency Ec _TGT calculated here is transmitted to the target in-cylinder air amount calculation unit 6d and the opening restriction release unit 7.

The target in-cylinder air amount calculation unit 6d uses the target charging efficiency Ec _TGT calculated by the target air amount calculation unit 6c as the target value Q of the intake flow rate (the amount of air in one intake stroke) introduced into the cylinder. Performs an operation to convert to _cca . The filling efficiency is the gas volume (volume per unit stroke) in the cylinder under standard conditions divided by the cylinder volume V _ENG . Therefore, the gas volume in the cylinder in the standard state is obtained by multiplying the filling efficiency by the cylinder volume V _ENG .

In the present embodiment, the target value Q _cca is obtained based on, for example, a preset correspondence map between the target charging efficiency Ec _TGT and the target value Q _cca , a mathematical expression, or the like. A correction factor that is set according to the intake air temperature (outside air temperature AT), actual intake manifold pressure P _IM , intake air density, etc., considering the case where the pressure and temperature of the intake air introduced into the cylinder are different from the standard state. _{Alternatively} , the target value Q _cca may be calculated. The target value Q _cca calculated here is transmitted to the intake air advance compensation unit 6e.

The intake air advance compensation unit 6e performs a process opposite to the delay process performed by the intake air delay correction unit 5c of the target torque calculation unit 5. The calculation contents before the input to the intake air advance compensation unit 6e relate to the torque and air amount in each cylinder of the engine 10, whereas the calculation content after the intake air advance compensation unit 6e is the throttle valve. 23 relates to the intake air passing through 23. Here, based on the intake characteristics relating to the engine 10, the intake manifold 20, the surge tank 21, the throttle valve 23, and the like, the second target value Q _{cca2 is obtained by performing} reverse calculation (intake advance calculation) of the intake delay on the target value Q _cca . Is calculated.

Note that a specific method of calculating the intake air advance is arbitrary. For example, it is conceivable to adopt a method of calculating an extrapolated value on the _{assumption that} the past change gradient of the target value Q _cca is maintained after this time. As a simple method, a value obtained by multiplying the amount of change from the previous value of the target value Q _cca to the current value by a predetermined filter coefficient may be added to the current value. The second target value Q _cca2 calculated _here is transmitted to the target flow rate calculation unit 6f.

The target flow rate calculation unit 6f calculates the target flow rate Q _{TH_TGT} of the intake air passing through the throttle valve 23 based on the second target value Q _cca2 transmitted from the intake air advance compensation unit 6e. The second target value Q _cca2 is a value corresponding to the amount of air that should pass through the throttle valve 23 in one intake stroke. Therefore, here, the value of the second target value Q _cca2 is converted based on the actual rotational speed Ne, and the target flow rate Q _{TH_TGT} per unit time is calculated. The target flow rate Q _{TH_TGT} calculated here is transmitted to the throttle area calculation unit 6h.

The flow velocity calculation unit 6g calculates the flow velocity V of the intake air passing through the throttle valve 23. Here, the flow velocity V is calculated based on the ratio of the downstream pressure P _IM for upstream pressure P _THU of the throttle valve 23 (or the atmospheric pressure _{P BP) (P IM / P} THU). The flow velocity calculation unit 6g calculates the flow velocity V using, for example, a map or a mathematical formula that defines a change in the flow velocity V depending on the front-rear pressure ratio of the throttle valve 23. The flow velocity V calculated here is transmitted to the throttle area calculation unit 6h.

The throttle area calculator 6h calculates a target throttle area S of the throttle valve 23 based on the target flow _{QTH_TGT} calculated by the target flow calculator 6f and the flow velocity V calculated by the flow velocity calculator 6g. For example, as shown in FIG. 8, the target throttle area S is obtained by dividing the target flow rate Q _{TH_TGT} by the value obtained by multiplying the flow velocity V by the mass flow velocity M _MACH under the critical condition (the condition where the flow velocity V is the sonic velocity). The mass flow rate M _MACH is a value that is calculated in consideration of a change in air density due to temperature, and is set based on, for example, the outside air temperature AT and the upstream pressure P _THU detected by the outside air temperature sensor 39. The value of the target throttle area S calculated here is transmitted to the opening restriction release unit 7.

On the other hand, the upper limit area calculation unit 6b calculates an upper limit value S _LIM of the target throttle area S when the engine is started. Here, the upper limit value S _LIM is set based on the coolant temperature W _TS. Upper area calculation unit 6b, for example, as shown in FIG. 9, by using a map or a mathematical expression or the like that defines the relation between the cooling water temperature W _TS and the upper limit value S _LIM, calculates the upper limit value S _LIM. In the present embodiment, as shown in solid lines in FIG. 9, the value of the cooling water temperature W _TS lower the upper limit value S _LIM is increased, such as the value of the higher cooling water temperature W _TS upper limit S _LIM is reduced It is set.

Further, upper limit area calculation unit 6b sets upper limit value S _LIM having different magnitudes during cranking of engine 10 and after startup (after it is determined that engine 10 has been started by cranking). The broken line in FIG. 9 corresponds to the setting of the upper limit value S _LIM1 during cranking, and the solid line corresponds to the setting of the upper limit value S _LIM2 after startup (after cranking). Thus, the value (second upper limit value) of the upper limit value S _LIM2 after starting the engine 10 is set to a value smaller than the value (first upper limit value) of the upper limit value S _LIM1 set during cranking. The That is, the target throttle area S is more strongly limited after starting than during cranking.

However, the magnitudes of these upper limit values S _LIM1 and S _LIM2 can be set in accordance with the startability, exhaust performance, rotational stability, etc. required for the engine 10. Therefore, the magnitude relationship between the upper limit value S _LIM1 upper limit S _LIM2 and cranking after starting is not always constant, for example, an upper limit value S _LIM2 after the start greater then than the upper limit S _LIM1 in cranking May be. Information on the upper limit values S _LIM1 and S _LIM2 calculated here is transmitted to the opening degree limit release unit 7. Hereinafter, when it is not necessary to distinguish between these upper limit values S _LIM1 and S _LIM2 , they are simply expressed as upper limit values S _LIM .

[2-6. Opening limit release part]
The opening restriction release unit 7 performs opening restriction control for limiting the actual throttle opening θ _TH by limiting the target throttle area S calculated by the start throttle opening restriction unit 6 to the upper limit value S _LIM or less. To implement. The opening restriction control is started when cranking of the engine 10 is started. In addition, the end condition of the opening restriction control is, for example, a combination of conditions listed below. In the present embodiment, the opening degree restriction control ends when both the condition 19 and the condition 20 are satisfied, or when any of the condition 18, the condition 21, the condition 22, and the condition 23 is satisfied.

Condition 18: The target intake manifold pressure P _{IM_TGT} required to realize the target charging efficiency Ec _TGT is
The actual intake manifold pressure P _IM or in a condition 19: actual rotational speed condition change rate? Ne _TH is smaller than a predetermined change rate? Ne _TH0 of Ne 20: Conditions advancing margin of the ignition timing is equal to or less than the predetermined value 21: engine 10 The engine is stalled (the engine 10 is stopped)
Condition 22: Conditions sensor fault is detected 23: elapsed time C _AS from the time of start-up exceeds a predetermined time T _THCRK

The condition 18 is a condition mainly corresponding to the accelerator operation by the driver. For example, an output required of the engine 10 is increased by depression of the accelerator pedal, when the air amount exceeding the amount of air can not be introduced in the actual intake manifold pressure P _IM at that time is required, the opening limit control To end normal control. Conditions 19 and 20 are mainly when there is no accelerator operation and the engine speed increases poorly (when the actual rotational speed Ne is small or when the actual rotational speed Ne is decreasing). In other words, it is a condition for ending the opening restriction control.

  The condition 21 is a condition corresponding to the time when the engine 10 is stopped (for example, before the engine 10 is started), and the condition 22 is a condition assuming a failure of the air flow sensor 34 or the intake manifold pressure sensor 37. Further, the condition 23 is a condition for determining an elapsed time based on the determination of starting the engine 10 after cranking.

The “predetermined time T _THCRK ” in the condition 23 includes the time when the engine 10 is manually started (or when restarting from the idle stop state and restarting other than the D range) and the idle stop state. A different time is set when starting from (for example, when restarting in the D range). For example, the former time (second time) is shorter than the latter time (first time). That is, at the time of starting from the idling stop state, the opening time limit control time is extended as compared to other starting times.

  Even when starting from the idle stop state, for example, when starting in the N range, the opening time limit control time may be set to the same value as when starting the key. This is because when the engine is started in the general N range, the power transmission path of the engine 10 is often cut off as in the key start. However, in consideration of the merit in terms of fuel consumption and exhaust performance immediately after startup, a control configuration may be adopted in which the execution time of the opening restriction control is extended even when starting in the N range. At least, the opening time of the opening restriction control at the start of the engine 10 excluding “at the time of starting from the idle stop state” is set shorter than the execution time of the opening restriction control at the time of “starting from the idle stop state”. It is preferable.

In the opening restriction control, the throttle opening θ _TH is controlled based on the target throttle area S calculated by the starting throttle opening restriction unit 6 and the upper limit value S _LIM calculated by the upper limit area calculation unit 6b. First, when the engine 10 is stalled (the engine 10 is in a stopped state), one of the target throttle area S and the upper limit value S _LIM is selected, and this is the final throttle opening θ. The target opening area of _TH . Further, during cranking of the engine 10, the throttle opening θ _TH is controlled based only on the upper limit value S _LIM .

On the other hand, after cranking is completed and the engine 10 is started, one of the target throttle area S and the upper limit value S _LIM having a smaller value is selected, which is the final target opening area of the throttle opening θ _TH. Is done. Note that after the opening restriction control is completed, the target throttle area S is set as the final target opening area of the throttle opening θ _TH .

  In order to perform the condition determination as described above, as shown in FIG. 11, the opening degree restriction releasing unit 7 includes a volumetric efficiency coefficient calculating unit 7a, a target pressure calculating unit 7b, an actual charging efficiency calculating unit 7c, and a maximum torque calculation. A unit 7d, an ignition efficiency coefficient calculation unit 7e, and a condition determination unit 7f are provided.

The volume efficiency coefficient calculation unit 7a (volume efficiency coefficient calculation means) calculates a volume efficiency coefficient K _MAP that is an index value for evaluating the intake performance of the engine 10. Volumetric efficiency coefficient K _MAP is obtained by standardizing the volumetric efficiency Ev based on the intake system pressure, for example, corresponds to the actual intake manifold pressure P _IM is converted into a value when the atmospheric pressure P _BP. The volumetric efficiency coefficient K _MAP is calculated based on the pressure ratio R _PRS that is the ratio of the downstream pressure (actual intake manifold pressure P _IM ) to the upstream pressure P _THU of the throttle valve 23 and the actual rotational speed Ne. Volumetric efficiency coefficient calculating portion 7a calculates, for example, corresponding map and equations between the actual rotational speed Ne and pressure ratio R _PRS and volumetric efficiency coefficient K _MAP as shown in FIG. 10, based on the relational expression or the like, the volumetric efficiency coefficient K _MAP To do. The value of the volumetric efficiency coefficient K _MAP calculated here is transmitted to the target pressure calculation unit 7b.

The target pressure calculation unit 7b (pressure calculation means) is configured to _perform target filling based on the volume efficiency coefficient K _MAP calculated by the volume efficiency coefficient calculation unit 7a and the target charging efficiency Ec _TGT calculated by the target air amount calculation unit 6c. The target intake manifold pressure _{PIM_TGT} , which is the intake manifold pressure equivalent to the efficiency Ec _TGT , is calculated. The target intake manifold pressure P _{IM_TGT} corresponds to the actual intake manifold pressure P _IM when the intake air having the air amount corresponding to the target charging efficiency Ec _TGT is introduced into the cylinder, and is given by, for example, the following Expression 4.

The actual charging efficiency calculation unit 7c calculates an actual charging efficiency Ec that is a charging efficiency corresponding to the amount of air actually introduced (introduced) into the cylinder. The actual charging efficiency Ec is calculated based on the intake air flow rate Q _IN that has passed through the throttle valve 23 and the actual rotational speed Ne of the engine 10. The value of the actual charging efficiency Ec calculated here is transmitted to the maximum torque calculator 7d.

The maximum torque calculator 7d calculates the maximum torque that can be generated in the cylinder to be controlled as the maximum actual torque _{PiACT_MBT} . The maximum actual torque _{PiACT_MBT} is a torque _generated when the ignition timing is set to the MBT ignition timing (also simply referred to as MBT; Minimum spark advance for Best Torque) with the actual charging efficiency Ec. The maximum torque calculation unit 7d stores, for example, the correspondence relationship between the actual charging efficiency Ec, the actual rotational speed Ne, and the torque at MBT generated at the stoichiometric air-fuel ratio as a map or a mathematical expression, and using this, the maximum actual torque _{PiACT_MBT} Is calculated. The maximum actual torque _{PiACT_MBT} calculated here is transmitted to the ignition efficiency coefficient calculation unit 7e.

The ignition efficiency coefficient calculation unit 7e calculates the _ratio between the target torque _{Pi_TGT} for ignition control calculated by the target torque calculation unit 5 and the maximum actual torque _{PiACT_MBT} calculated by the maximum torque calculation unit 7d as the ignition efficiency coefficient K _IGN. To do. Here, the maximum actual torque Pi _{ACT_MBT} that can be generated by the engine 10, whether the ignition controlling target torque Pi _{_TGT} accounts for how much percentage of is calculated. In ignition efficiency coefficient calculation unit 7e of the present embodiment, be required excessive ignition control target torque Pi _{_TGT} that exceeds the maximum actual torque Pi _{ACT_MBT,} the ignition timing is advanced from the MBT ignition timing The ignition efficiency coefficient K _IGN is clipped within a range of 1 or less (0 ≦ K _IGN ≦ 1) so that there is no _occurrence . The value of the ignition efficiency coefficient K _IGN calculated here is transmitted to the condition determination unit 7f.

The condition determination unit 7f (release means, control means) performs the opening degree restriction control of the throttle valve 23 based on the success / failure determination of the above conditions 18-23. For example, conditions 18 are determined that satisfied when the target intake manifold pressure P _{IM_TGT} calculated by the target pressure calculating section 7b is the actual intake manifold pressure P _IM more. The gradient difference ΔdNe calculated by the gradient difference calculation unit 4f may be used as the change rate ΔNe _TH of the condition 19, but the change rate (for example, obtained in the previous calculation cycle) with a shorter unit time. It is preferable to use a difference from the actual rotational speed Ne. Condition 19 is determined to be satisfied when the rate of change ΔNe _TH per unit time of the actual rotational speed Ne is less than the predetermined rate of change ΔNe _TH0 . The condition 20 is determined to be satisfied when the value obtained by subtracting the ignition efficiency coefficient K _IGN calculated by the ignition efficiency coefficient calculation unit 7e from 1.0 (1.0−K _IGN ) is equal to or less than the predetermined value K _0. .

When the cranking is started, the condition determination unit 7f performs the opening restriction control, and limits the target throttle area S to the upper limit value S _LIM or less until the end condition is satisfied. Here, the target throttle opening voltage E _L to achieve the throttle opening theta _TH corresponding to the upper limit value S _LIM is outputted to the throttle valve 23. Further, after the termination condition of the opening limit control is satisfied, the target throttle opening voltage E _L to achieve the throttle opening theta _TH in accordance with the target throttle area S is output to the throttle valve 23.

[3. Action of upper limit control]
[3-1. Restart to idling]
FIG. 12A shows the fluctuation of the actual rotational speed Ne of the engine 10 when the upper limit value control is performed at the time of restart from the idle stop state, and FIGS. 12B and 12C show the target torque, Shows fluctuations in ignition timing. At time t ₀ , idle stop control is performed while the vehicle is waiting for a signal, the operation position of the select lever is in the D range, the amount of depression of the accelerator pedal is 0, and the brake pedal is depressed in full stroke. It shall be assumed.

When a start request from the external load device is generated at time t ₀ and the above condition 10 is satisfied, restart control of the engine 10 is performed and cranking is started as shown in FIG. Thereafter, when the engine 10 starts at time t ₁ after the _first and complete explosions, the actual rotational speed Ne increases. On the other hand, the offset amount setting section 4b of the torque upper limit value calculating unit 4, the offset amount? Ne _OFS is set based on the coolant temperature W _TS.

The condition determination unit 4m determines whether or not the above conditions 11 to 13 are satisfied. Condition 11, since the actual rotational speed Ne is not satisfied unless it exceeds the start completion determination speed Ne _S, the unstable rotation state the actual rotational speed Ne is less than the start completion determination speed Ne _S, the upper limit control Not started. Condition 12 does not hold unless the actual rotational speed Ne exceeds this reference, with the value obtained by subtracting the offset amount ΔNe _OFS from the upper limit rotational speed Ne _{LIM_H} as a reference. Since the offset amount ΔNe _OFS is changed according to the cooling water temperature W _TS , the starting condition for the upper limit control depends on the cooling water temperature W _TS . Figure 5 (d), the when the offset amount? Ne _OFS As the cooling water temperature W _TS is increased is smaller, the higher the cooling water temperature W _TS, the upper limit control start condition is satisfied real The rotational speed Ne increases.

Condition 13, the torque required for the engine 10 at that time is a value obtained by converting an upper limit gradient dNe _{_H} the torque corresponding to the maximum value of the future change in the gradient of the actual rotational speed Ne (i.e., the torque correction value _Pi dNe_H) If it is not larger, it will not be established. In other words, when the torque applied to the rotation speed variation that exceeds the upper limit gradient dNe _{_H} calculated by the upper limit gradient calculating unit 4d is required, condition 13 is satisfied.

If the condition 11 to 13 at time t ₂ is satisfied all the upper limit control is performed. In the rotational speed upper limit setting unit 4a, the maximum possible values (first upper limit value, second upper limit value, second upper limit value) of the actual rotational speed Ne for each of the accelerator operation amount A _PS , the brake fluid pressure B _RK , and the coolant temperature W _TS . 3 upper limit values) are set, and an upper limit rotation speed Ne _{LIM_H} is set as shown by a one-dot chain line in FIG.

The upper limit rotational speed Ne _{LIM_H} set in the upper limit control is set to a size corresponding to the operation position of the select lever, for example, as shown in FIGS. 5A and 5B, and the D range is selected. In the state, the upper limit rotational speed Ne _{LIM_H} is set smaller than in the other ranges. That is, when the engine is started in the D range, the one-dot chain line in FIG. 12A is set downward, and the action of suppressing the actual rotational speed Ne is strengthened.

In the upper limit control, limit gradient dNe _{_H} corresponding to the rotational speed difference ΔNe between the upper limit rotation speed Ne _{LIM_H} and the actual rotation speed Ne is calculated, i.e. the engine so as to suppress the rotational speed variation that exceeds the upper limit gradient dNe _{_H} Ten target torques are corrected in a decreasing direction. In the gradient difference calculation section 4f, the gradient difference ΔdNe the upper slope dNe _{_H} and the actual rate of change dNe is calculated, the torque correction amount computing section 4g the torque correction value Pi _{DNe_H} is calculated. Further, the upper limit torque calculation unit 4k calculates the upper limit torque Pi _{LIM_H} .
The upper limit rotation speed Ne _{LIM_H} is set to a value equal to or higher than the target idle rotation speed Ne _OBJ . Therefore, the width between the target idle rotation speed Ne _OBJ and the upper limit rotation speed Ne _{LIM_H} is the fluctuation width of the rotation speed allowed for the actual rotation speed Ne.

The upper limit torque Pi _{LIM_H} calculated by the torque upper limit calculation unit 4 is transmitted to the target torque calculation unit 5, and is reflected as the upper limit values of the intake control target torque Pi _{ETV_STD} and the ignition control target torque _{Pi_TGT} . Thus, for example, as shown in FIG. 12 (c), the ignition timing of the ignition plug 13 is greatly retarded at time t ₂ later, is controlled so that the engine torque is reduced. Further, as shown by a solid line in FIG. 12 (b), the target value of the engine torque (target torque) is reduced significantly at time t ₂ later. By such control, for example, as indicated by a broken line in FIG. 12A, the actual rotational speed Ne does not increase rapidly immediately after the start, and the engine speed is reliably suppressed.

Immediately after the time t _2, the actual rotational speed Ne further approaches the upper limit rotation speed Ne _{LIM_H,} rotational speed difference ΔNe is reduced. Accordingly, the upper limit gradient dNe _{_H} calculated by the upper limit gradient calculating unit 4d is reduced, the width of the rotational speed variation allowed for the actual rotational speed Ne decreases. That is, as the actual rotational speed Ne approaches the upper limit rotational speed Ne _{LIM_H} , the function of suppressing the rotational speed fluctuation is strengthened.

On the other hand, the actual rate of change dNe of the engine rotation speed becomes smaller with the rotation speed variation is suppressed, also decreasing gradient difference ΔdNe real change rate dNe for upper gradient dNe _{_H.} When the time t ₃ and the upper slope dNe _{_H} and the actual rate of change dNe match, next the gradient difference ΔdNe is 0, the torque correction value Pi _{DNe_H} calculated by the torque correction amount computing section 4g becomes 0. Therefore, the time t ₃ after is in a state in which no torque is in effect limit. At this time, the target torque of the engine 10 is equal to or less than the upper limit torque Pi _{LIM_H} as shown in FIG. However, since the upper limit control is continued until the end condition is satisfied, for example, when the actual rotational speed Ne of the engine 10 increases again after time t ₃ , the rotational speed fluctuation is suppressed.

When the actual rate of change dNe becomes 0 at time t _4, the idle torque demand Pi _{_NeFB} is selected in the intake selector 5a and the ignition selector 5f target torque computing unit 5, the idle feedback control is started. Thus, the torque is controlled so that the actual rotational speed Ne of the engine 10 converges smoothly toward the target idle rotational speed _NeOBJ . That is, based on the required idle torque Pi _{_NeFB,} and the intake control target torque Pi _{ETV_STD} ignition controlling target torque Pi _{_TGT} is calculated, the throttle opening theta _TH and the fuel injection quantity, ignition timing, etc. are controlled.

[3-2. Restart to creep start]
FIG. 13 exemplifies the control action of the upper limit control when the engine 10 is restarted when the driver's brake operation is loosened in the idle stop state, and FIG. The fluctuation of the hydraulic pressure B _RK ) is shown, and FIG. 13B shows the fluctuation of the actual rotational speed Ne.

When the brake operation is loosened at time t _A the brake fluid pressure B _RK is less than the predetermined value, it satisfied the above conditions 8, cranking is started is implemented restart control. Further, after the engine 10 is started at time t _5, when the conditions 11 to 13 are satisfied all the time t _6, the upper limit control is performed. In the rotational speed upper limit setting unit 4a, as shown in FIG. 5C, the first upper limit value corresponding to the brake hydraulic pressure _BRK is set to increase as the brake hydraulic pressure _BRK decreases.

As a result, as indicated by the alternate long and _short dash line in FIG. _13B , the upper limit rotational speed Ne _{LIM_H} is set higher as the brake pedal depression operation is loosened. In other words, the upper limit rotational speed Ne _{LIM_H} is set larger as the driver's intention to start is larger, and conversely, the upper limit rotational speed Ne _{LIM_H} is set smaller as the _driver's intention to start is smaller. The time t _{B at which} the gradient of the change over time of the upper limit rotational speed Ne _{LIM_H} changes coincides with the time t _{B at} which the gradient of the brake operation amount changes over time. Note that when the brake operation amount becomes zero at time t _C , the rate of increase of the upper limit rotational speed Ne _{LIM_H} also becomes zero.

Thus, since the upper limit rotational speed Ne _{LIM_H} is set higher as the brake operation is loosened, the actual rotational speed Ne tends to increase. However, the fluctuation of the actual rotation speed Ne is limited to the range below the upper limit rotation speed Ne _{LIM_H} . Therefore, torque required for creep travel is ensured, startability of the engine 10 is not impaired, and racing is suppressed. Incidentally, the elapsed time after engine start upper limit control exceeds the time t ₇ as a predetermined time limit ends, normal torque control is continued thereto.

[3-3. Restart to accelerator start]
FIG. 14 illustrates the control action of the upper limit control when the accelerator pedal is depressed immediately after the engine 10 is restarted from the idle stop state, and FIG. 14 (a) shows the brake operation amount (brake fluid) variation of pressure B _RK), FIG. 14 (b) fluctuations in the accelerator operation amount a _PS, FIG. 14 (c) respectively a variation of the actual rotational speed Ne.

When the brake operation is loosened at time t _D is the brake fluid pressure B _RK is less than the predetermined value, it satisfied the above conditions 8, cranking is started is implemented restart control. Further, after the engine 10 is started at time t _8, the conditions 11 to 13 at time t ₉ is when all satisfied, the upper limit control is performed.

In the rotation speed upper limit setting unit 4a, a higher first upper limit is set as the brake fluid pressure _BRK decreases. When the brake operation amount becomes 0 at time t _E and the accelerator pedal starts to be depressed, the rotation speed upper limit value setting unit 4a increases the accelerator operation amount A _PS as shown in FIG. 5A. Thus, the third upper limit value corresponding to this is also set to increase.

Accordingly, as indicated by the alternate long and _{short dash} line in FIG. _14C , the upper limit rotational speed Ne _{LIM_H} is set higher as the brake pedal depressing operation is loosened or the accelerator pedal depressing operation is strengthened. Time t _E the slope of the change with time of the upper limit rotation speed Ne _{LIM_H} changes, t _F, t _G, respectively, the time t _E the slope of the change with time of the brake operation amount and the accelerator operation amount changes, t _F, the t _G Match. Incidentally, when the accelerator depression operation amount becomes maximum at time t _G, the rate of increase in the upper limit rotation speed Ne _{LIM_H} is also zero.

As described above, the upper limit rotational speed Ne _{LIM_H} is set high, so that the actual rotational speed Ne is likely to increase within the range of the upper limit rotational speed Ne _{LIM_H} or less. That is, the actual rotational speed Ne is likely to increase according to the driver's intention to start, and the accelerator required torque _{Pi_APS} is easily secured. The upper limit control ends exceeds the time t ₁₀ to the time elapsed after the start of the engine becomes a predetermined time limit.

[4. Flow chart of opening limit control]
FIG. 15 is a flowchart illustrating the procedure of opening degree restriction control performed by the engine control apparatus 1. In step A10, it is determined whether or not the idle switch is on (for example, the accelerator pedal is not depressed and the accelerator operation amount _APS is zero). Here, when the idle switch is off, the accelerator pedal is depressed, so the process proceeds to step A20 for determining the condition 18, and when the idle switch is on, the process proceeds to step A30.

In step A20, whether or not the target intake manifold pressure P _{IM_TGT} is less than the actual intake manifold pressure P _IM is determined. Here, if P _{IM_TGT} <P _IM is satisfied, the process proceeds to step A30. On the other hand, if P _{IM_TGT} <P _IM is not satisfied, that is, if P _{IM_TGT} ≧ P _IM is satisfied, the above condition 18 is satisfied, so that the _routine proceeds to step A70 and the throttle opening θ _TH is limited. Canceled. That is, in this step, the target opening area of the final throttle opening θ _TH is set to the target throttle area S, and the opening restriction control is finished. Thereafter, the above-described upper limit control may be performed, or normal torque control, idle feedback control, or the like may be shifted to without performing the upper limit control.

In step A30 and subsequent steps, conditions corresponding to the above-described condition 19 and subsequent steps are determined. First, in step A30, it is determined whether or not the change rate ΔNe _TH of the actual rotational speed Ne of the engine 10 is equal to or greater than a predetermined change rate ΔNe _TH0 . If ΔNe _TH ≧ ΔNe _TH0 is satisfied, the process proceeds to step A50, and if not, the process proceeds to step A40.

In step A40, it is determined whether or not a value obtained by subtracting the ignition efficiency coefficient K _IGN from 1.0 (1.0−K _IGN ) exceeds a predetermined value K ₀ . Here, when (1.0−K _IGN )> K ₀ is satisfied, the condition 20 is not satisfied, and the process proceeds to step A50. On the other hand, if (1.0−K _IGN )> K ₀ is not satisfied, the condition 20 is satisfied, and the process proceeds to Step A70. Also in this case, the target opening area of the final throttle opening θ _TH is set to the target throttle area S, and the opening restriction control ends.

In step A50, the elapsed time C _AS from during startup or less than a predetermined time T _THCRK is determined. If C _AS ≦ T _THCRK is satisfied, the process proceeds to step A60. If not satisfied, the process proceeds to step A70, and the opening degree restriction control is terminated. When restarting in the D range from the idle stop state, the predetermined time T _THCRK is set longer than when restarting in the N range or when starting the key. Therefore, when restarting in the D range from the idle stop state, the opening degree restriction control can be performed for a relatively long time.

  In Step A60, it is determined whether or not a sensor failure has not been detected. Here, if no failure has occurred in the sensors related to the opening limit control, the process proceeds to step A90. On the other hand, for example, when a failure of the air flow sensor 34 or the intake manifold pressure sensor 37 is detected, the process proceeds to step A70, and the opening degree restriction control ends.

In step A90, it is determined whether or not the engine 10 is stalled. Here, if the engine is stalled, the process proceeds to step A100, and one of the target throttle area S and the upper limit value S _LIM having the larger value is selected, and this is set as the final target opening area of the throttle opening _θTH . In this step, the opening degree restriction control is substantially cancelled. On the other hand, if the engine is not stalled, the process proceeds to step A110.

In step A110, it is determined whether or not the engine 10 is being cranked. If cranking is in progress, the process proceeds to step A120. Otherwise, the process proceeds to step A130. In step A 120, the upper limit value S _LIM is targeted opening area of the final throttle opening theta _TH, the throttle opening theta _TH is limited. On the other hand, when the process proceeds to step A130, one of the target throttle area S and the upper limit value S _LIM having a smaller value is selected, and this is set as the final target opening area of the throttle opening _θTH .

[5. Action of opening limit control]
The effect | action by opening degree restriction | limiting control is demonstrated using Fig.16 (a)-(e). Here, it is assumed that the vehicle is temporarily stopped waiting for a signal and the engine 10 is stopped by the automatic stop control.

As shown in FIG. 16 (a), the brake operation amount of the brake pedal is released at time t ₁₁ is less than the predetermined value, the restart condition is satisfied. At this time, as shown in FIG. 16C, cranking for restarting the engine 10 is started, and opening degree restriction control is started. Target throttle area S of the throttle opening theta _TH, as shown in FIG. 16 (e), is fixed to the upper limit value S _LIM1 in cranking set in the upper area calculating section 6b, the engine output is suppressed.

The engine 10 is first explosion, through the complete explosion and restarted at time t _12, the value of the upper limit value S _LIM2 set in the upper limit area calculation unit 6b is further smaller than the upper limit value S _LIM1 in cranking The target throttle area S is more strongly suppressed. As a result, for example, the occurrence of racing immediately after starting as shown by the broken line in FIG. 16C is avoided, and the actual rotational speed Ne increases gently.

On the other hand, as shown in FIG. 16 (b), when the accelerator pedal is depressed at time t ₁₃ immediately after the engine 10 is restarted, the accelerator demanded torque Pi _{_APS} increases in response to the accelerator operation amount A _PS. The accelerator required torque _{Pi_APS} is _reflected in the ignition control target torque _{Pi_TGT} and the intake control target torque Pi _{ETV_STD,} and the actual rotational speed Ne of the engine 10 gradually increases. However, the target throttle area S remains limited to the upper limit value S _LIM2 or less unless the condition for terminating the opening degree restriction control is satisfied, and excessive output and exhaust gas deterioration are suppressed.

Further, with the increase in the actual rotational speed Ne, the actual intake manifold pressure P _IM gradually decreases. On the other hand, the target intake manifold pressure _{PIM_TGT} calculated by the target pressure calculation unit 7b of the opening restriction release unit 7 increases as the target charging efficiency Ec _TGT increases. The amount of increase in the target intake manifold pressure P _{IM_TGT} increases as the target charging efficiency Ec _TGT increases or the volumetric efficiency coefficient K _MAP decreases. Accordingly, as shown in FIG. 16 (d), according to the operating condition of immediately after the start of the engine 10, and the actual intake manifold pressure P _IM and the target intake manifold pressure P _{IM_TGT} gradually approaches the target intake manifold pressure at time t ₁₄ P _{IM_TGT} exceeds the actual intake manifold pressure P _IM .

At this time, the above condition 18 is satisfied, and the opening degree restriction control ends. As shown in FIG. 16 (e), is released in the target throttle area S limit, the throttle opening theta _TH is controlled such that the throttle area S is calculated based on the intake control target torque Pi _{ETV_STD.} As a result of the throttle valve 23 is opened, the actual intake manifold pressure P _IM gradually approaches the target intake manifold pressure P _{IM_TGT,} a state of the actual intake manifold pressure P _IM and the target intake manifold pressure P _{IM_TGT} matches.

Since the target intake manifold pressure P _{IM_TGT} is a pressure value required to achieve the target charging efficiency Ec _TGT , even if the actual intake manifold pressure P _IM exceeds the target intake manifold pressure P _{IM_TGT} , the opening restriction control is continued. Even so, the engine output corresponding to the driver's accelerator request is maintained. That is, in the above control, the opening degree restriction control is ended when the engine is in an operating state where the engine output becomes insufficient. As a result, starting stability and environmental performance from cranking to starting after engine 10 are maintained, and even if the accelerator operation is performed immediately after starting, the startability and acceleration of the vehicle are ensured.

[6. Effect of upper limit control]
Thus, according to the engine control apparatus 1 of the present embodiment, the following effects can be obtained.
(1) In the engine control device 1 described above, the actual rotational speed Ne of the engine 10 is controlled so as not to exceed the upper limit rotational speed Ne _{LIM_H,} and the upper limit rotational speed Ne _{LIM_H} is set smaller as the intention to start is smaller. For example, as shown in FIGS. 5A and 5B, the smaller the accelerator operation amount A _PS or the higher the brake hydraulic pressure B _RK , the corresponding first upper limit value and second upper limit value. Is set small, and these values are reflected in the upper limit rotational speed Ne _{LIM_H} finally selected. As a result, it is possible to suppress the sudden increase (swing up) of the actual rotational speed Ne that may occur immediately after the engine 10 is started, and to reduce the unnecessary running feeling. On the contrary, since the upper limit rotational speed Ne _{LIM_H} is set to be larger as the intention to start is larger, sufficient acceleration according to the intention to start can be obtained.

Further, as shown in FIG. 12 (a), at the upper limit control, the idle feedback control rather than reduce the target idle rotational speed Ne _OBJ, the actual rotational speed Ne that greatly exceeds the target idle rotation speed Ne _OBJ Suppression is suppressed. Thereby, rotation speed fluctuation | variation and torque fluctuation | variation can be reduced, ensuring the startability of the engine 10. FIG.

(2) In addition, regarding the setting of the upper limit rotational speed Ne _{LIM_H} based on parameters corresponding to the driver's intention to start, such as the accelerator operation amount A _PS and the brake hydraulic pressure B _RK , the engine control apparatus 1 described above has a final upper limit rotational speed. The value of the speed Ne _{LIM_H} is set to the minimum value selected by the minimum value selection unit 46. For example, as shown in FIG. 4, the upper limit rotation speed Ne _{LIM_H that} is finally selected is one of the fourth upper limit value and the fifth upper limit value that is more restrictive. Therefore, when the brake pedal depressing operation and the accelerator pedal depressing operation are performed at the same time, the upper limit value can be controlled using the upper limit value that can be applied with a stronger limit. While satisfying the acceleration performance according to the intention, it is possible to suppress the sudden increase (swing up) of the engine rotation, and to reduce the unnecessary running feeling.

(3) Further, the variation gradient of the actual rotational speed Ne, by calculating the torque correction value Pi _{DNe_H} the gradient difference ΔdNe between a control target upper slope dNe _{_H} and the actual rate of change dNe in terms of torque, actual the rotational speed Ne along the upper slope dNe _{_H} can be varied precisely, a sudden change and racing of the actual rotational speed Ne can be suppressed.

(4) Since the upper limit rotational speed Ne _{LIM_H} is set to a value equal to or higher than the target idle rotational speed Ne _OBJ set by the target idle rotational speed setting unit 3a, the actual rotational speed Ne is not excessively suppressed. Immediately after startup, the actual rotational speed Ne can be raised to the vicinity of the target idle rotational speed Ne _OBJ . In this way, it is possible to suppress the racing while ensuring rotational stability immediately after the engine 10 is started.

(5) In the engine control apparatus 1 described above, the idle feedback control is performed from the time when the actual change rate dNe of the actual rotational speed Ne after starting the engine 10 becomes 0 or less for the first time. As a result, the actual rotational speed Ne can be smoothly and rapidly converged to the target idle rotational speed Ne _{OBJ as} compared with the conventional control in which the idle feedback control is performed according to the elapsed time after the start, for example. Further, it is possible to shorten the time required until the idle rotation of the engine 10 is stabilized.

(6) Further, in the engine control apparatus 1 described above, the brake operation is referred to as one of the start intentions by the driver, and it is determined that the start intention is larger as the brake operation amount is smaller. Ne _{LIM_H} is set large. By such control, the required creep torque can be ensured while suppressing the racing immediately after the engine 10 is started. In particular, it is possible to improve both the starting stability and the starting stability of the vehicle at the time of restart from the idle stop control.

(7) Similarly, in the engine control apparatus 1 described above, the accelerator operation is referred to as one of the intentions of the driver to start, and the higher the accelerator operation amount, the greater the intention to start, and the upper limit rotation. Speed Ne _{LIM_H} is set large. By such control, acceleration can be improved while suppressing a blow-up immediately after the engine is started. In particular, it is possible to improve both the starting stability and mobility of the vehicle at the time of restart from idle stop control.

(8) In the above-described engine control device 1, as shown in FIG. 5 (b), the cooling water temperature W _TS is the higher upper limit rotation speed Ne _{LIM_H} is set smaller. That is, when the engine is sufficiently warmed up, the friction related to the driving of the engine 10 is reduced, and it is easy for the engine to blow up. As a result, it is possible to more appropriately suppress the engine blow-up immediately after the engine 10 is started, and to reduce unnecessary running feeling and torque shock. In addition, by setting the magnitude of the limit by the upper limit control in consideration of friction, the magnitude of the creep torque during creep running can be optimized.

(9) In the above-described engine control device 1, as shown in FIG. 5 (e), as the upper limit gradient dNe _{_H} higher the actual rotational speed Ne of the engine 10 approaches the upper limit rotation speed Ne _{LIM_H} approaches zero, the future The gradient of change is set. With such a setting, even if the increase speed or increase amount of the actual rotation speed Ne is abrupt, it is possible to control the range of the upper limit rotation speed Ne _{LIM_H} or less by adding a large limit to the increase in the actual rotation speed Ne. . Further, if the increase speed and increase amount of the actual rotation speed Ne are slow, the actual rotation speed Ne can be stably increased by adding a relatively small restriction. Therefore, it is possible to start the engine 10 at an appropriate actual rotational speed Ne while suppressing the rising of the actual rotational speed Ne.

(10) In the engine control apparatus 1 described above, the torque correction value _{PidNe_H} is calculated by the torque correction amount calculation unit 4g. And the torque correction value _Pi dNe_H, is obtained by converting the change in slope of the future actual rotational speed Ne a torque must be reduced to below the upper limit gradient dNe _{_H,} a gradient difference ΔdNe torque. Such torque converted value by carrying out the torque based control by using a can be varied accurately along the actual rotational speed Ne to the gradient of the target value (the upper limit gradient dNe _{_H).}

(11) In the above-described engine control device 1, the offset amount setting section 4b of the torque upper limit value calculating unit 4, the offset amount? Ne _OFS based on the cooling water temperature W _TS is set. The offset amount? Ne _OFS, for example as specified in condition 12, is a parameter for determining a condition for starting the upper limit control, that value as the cooling water temperature W _TS is lower as the offset amount? Ne _OFS increases Is set. As a result, the upper limit control when the cooling water temperature _WTS is low can be started at an early stage, and the increase in the actual rotational speed Ne can be effectively suppressed. On the other hand, as shown in FIG. 5D, when starting at an extremely low cooling water temperature _WTS at an extremely low temperature, the offset amount ΔNe _OFS is set slightly smaller, so that the start of the upper limit control can be delayed. Therefore, it is possible to make the control giving priority to the startability.

  (12) Some vehicles equipped with the AT unit 26 incorporating the torque converter 26a hold the shift range in the state of the D range during the idle stop control of the engine 10. In such a vehicle, at the time of restart control from the idle stop state, the engine 10 is restarted in the D range, and therefore, a torque shock may occur as the actual rotational speed Ne increases.

On the other hand, in a vehicle equipped with the engine control device 1, as shown in FIGS. 5A and 5B, the upper limit rotational speed Ne _{LIM_H} set when the operation position of the select lever is in the D range is D It is set to be smaller than the upper limit rotation speed Ne _{LIM_H} set when other than the range. That is, at the time of start-up in a situation where the engine torque can be input to the AT unit 26, the torque suppression action is further strengthened so that the increase in the actual rotational speed Ne subsides at a smaller level. As a result, the engine rotation is effectively suppressed, and the torque fluctuation at the start inputted from the output shaft of the engine 10 to the AT unit 26 is weakened. Therefore, an unnecessary running feeling of the vehicle can be reduced.

(13) Although the throttle valve is not fully opened at the start of a general engine, the pressure in the intake passage is almost the same as the atmospheric pressure P _BP , so the initial amount of in-cylinder intake air actually introduced into the cylinder The value corresponds to the flow rate detected by the flow rate detection means when the throttle valve is fully open. That is, the in-cylinder intake air amount immediately after the engine is started becomes a value larger than the flow rate detected by the flow rate detection unit, and fluctuates so as to gradually approach the flow rate detected by the flow rate detection unit as time elapses.

In view of the variation characteristics of the cylinder intake air amount, in the engine control device 1, as one of the termination conditions of the upper limit control, the estimated value of the filter value and the in-cylinder intake air amount of the intake air flow Q _IN Are almost identical. For example, as shown in FIGS. 6 (a) and 6 (b), until the estimated value (thick solid line) of the in-cylinder intake air amount matches the filter value (thin solid line) of the value detected by the airflow sensor 34. Upper limit control is performed. As a result, it is possible to effectively suppress engine blow-up until the pressure in the intake passage is constantly reduced to a negative pressure and stabilized.

[7. Effect of opening limit control]
(1) In the engine control apparatus 1 described above, excessive output and exhaust gas deterioration can be suppressed by limiting the target throttle area S of the throttle valve 23 to the upper limit value S _LIM or less when the engine 10 is started. On the other hand, by releasing the restriction on the basis of the magnitude of the actual intake manifold pressure P _IM, it can be reflected in real output request immediately after the start by the driver to the intake air amount. Therefore, acceleration performance can be improved while maintaining start stability and environmental performance, and drivability at start-up can be improved.

(2) Further, in the engine control apparatus 1 described above, as shown in the condition 19, the opening degree restriction control is canceled based not only on the actual intake manifold pressure _PIM but also on the rate of change ΔNe _TH of the actual rotational speed Ne of the engine 10. It has a configuration. Thus, when the increase in the actual rotational speed Ne is slightly slow, the throttle opening degree θ _TH can be easily controlled in the opening direction, the engine stall can be suppressed, and the rotational stability can be improved. On the other hand, when the rate of change ΔNe _TH of the actual rotational speed Ne is large, the opening degree restriction control is continued, and therefore, excessive rise and excessive torque can be suppressed without deteriorating exhaust emission. In this way, the degree of increase in the actual rotational speed Ne immediately after engine startup can be immediately reflected in the control amount of the intake air amount, and it is possible to stabilize the start while avoiding the risk of a decrease in engine rotational speed due to an insufficient intake air amount. Performance and environmental performance can be maintained, and drivability at start-up can be improved.

(3) Further, in the engine control apparatus 1 described above, as shown in the condition 20 determined together with the condition 19, the opening degree is based on not only the change rate ΔNe _TH of the actual rotational speed Ne but also the advance margin of the ignition timing. A configuration for releasing the restriction control is provided. Thus, the opening degree restriction control can be canceled only when the actual rotational speed Ne cannot be controlled even if the ignition timing is adjusted. Therefore, engine stall can be suppressed more efficiently.
On the other hand, when there is a lead angle margin, the actual rotational speed Ne can be stabilized by changing the ignition timing, and the restriction can be continued. As a result, a state where the throttle opening _θTH is relatively small can be maintained for a long time, and the effect of suppressing an unintended rotation increase and excessive torque can be enhanced.

In addition, by releasing the restriction on the throttle opening θ _TH based on the rate of change ΔNe _TH of the actual rotational speed Ne and the advance margin of the ignition timing, it is possible to reduce the rotational speed or reduce the engine speed when the engine is started without the accelerator pedal being depressed. Can be efficiently suppressed. In particular, at the time of cold start where the friction is relatively large, it is possible to suppress a decrease in the actual rotational speed Ne due to an excessive effect of the opening degree restriction control.

(4) Further, in the engine control device 1, when the target intake manifold pressure P _{IM_TGT} to a size corresponding to the accelerator operation amount is greater than the measured value of the actual intake manifold pressure P _IM, opening limiting control is canceled. As a result, the throttle opening θ _TH can be accurately controlled with respect to fluctuations in the intake performance immediately after the engine is started. For example, to stop the engine 10 is temporarily idle stop condition is satisfied, even when the restarted in a state where the actual intake manifold pressure P _IM is increased to the atmospheric pressure P _BP vicinity, according to the actual intake manifold pressure P _IM Thus, the state of the throttle opening θ _TH can be controlled appropriately. That is, if the actual intake manifold pressure _PIM is sufficiently high with respect to the amount of air required by the driver, the opening degree restriction control can be continued, and excessive engine output and exhaust gas deterioration can be suppressed. it can. On the other hand, if the actual intake manifold pressure _PIM is insufficient with respect to the amount of air required by the driver, the opening restriction control can be released, and the throttle opening _θTH is greatly opened to _meet the acceleration request. You can respond quickly.

(5) In the engine control apparatus 1 described above, the target intake manifold pressure P _{IM_TGT} is calculated using the volumetric efficiency coefficient K _MAP , so that the ease of entry of air (intake air) into the cylinder of the engine 10 is appropriately set. Can be evaluated. As a result, the target intake system pressure can be accurately obtained, and the timing for releasing the restriction on the target opening degree can be accurately controlled.

Incidentally, the volumetric efficiency Ev of the engine 10, the actual intake manifold pressure P _IM becomes smaller as drops. However, the relationship between the volumetric efficiency Ev and actual intake manifold pressure P _IM is not necessarily linear, the change amount (change gradient) volumetric efficiency Ev when changing the actual intake manifold pressure P _IM real intake manifold pressure P _IM decreases It gets bigger. This not only push-friendliness of the intake air of the cylinder the value of the volumetric efficiency Ev is determined by the actual intake manifold pressure P _IM, enters ease to the suction air of the cylinder determined in accordance with the operating condition such as the variable valve mechanism It is because it changes under the influence of the height.

On the other hand, since the volumetric efficiency factor K _map is obtained by standardizing the volumetric efficiency Ev in the intake system pressure, for example the actual intake manifold pressure P _IM is a value obtained by converting the volumetric efficiency Ev of the value of time at atmospheric pressure P _BP The actual intake manifold pressure P _IM is hardly affected by the ease of pushing in the intake air. Therefore, by using the volumetric efficiency coefficient K _map instead of the volumetric efficiency Ev, it becomes possible to remove the influence of the intake system pressure from the evaluation on the intake performance of the engine 10, and the ease of entering the intake air into the cylinder is objectively determined. Can grasp. Therefore, the controllability of the throttle opening θ _TH can be improved.

(6) Further, as shown in FIG. 9, since the upper limit value S _LIM is set based on the cooling water temperature W _TS , for example, the influence of friction due to temperature, the temperature characteristics of exhaust gas performance required for the engine 10, etc. Accordingly, an appropriate limit can be given to the throttle opening θ _TH .
(7) Furthermore, since the upper limit value S _LIM is set differently during cranking of the engine 1 and after starting, the throttle control according to the stability of the engine rotation becomes possible, and the exhaust gas performance is ensured while ensuring startability. Can be improved. For example, as shown in FIG. 16 (e), by setting the upper limit value S _LIM2 after starting lower than the upper limit value S _LIM1 during cranking, starting during cranking (for example, until the first explosion and complete explosion) It is possible to suppress excessive output and exhaust gas deterioration at the start after cranking while improving the performance.

  (8) Further, in the engine control apparatus 1 described above, the opening time limit control time at the time of key start is set shorter than that at the time of restart from the idle stop state. That is, when the engine 10 is at a relatively low temperature, the opening degree restriction control can be released early, the decrease in the actual rotational speed Ne due to friction can be suppressed, and the rotational stability can be improved. On the other hand, when restarting from the idling stop state, which has already been warmed up, the opening restriction control is continued for a slightly longer time, so that an unintended increase in the actual rotational speed Ne can be suppressed and the exhaust gas immediately after starting Performance can be improved.

(9) Further, in the engine control apparatus 1 described above, the throttle opening degree θ _TH is normally operated at the time of vehicle maintenance or inspection, for example, by canceling the opening degree restriction control in a state where the engine 10 is stopped (engine stall state). Can be confirmed, and maintainability can be improved.

[8. Modified example]
Various modifications of the upper limit control performed by the engine control device 10 are conceivable. For example, in the above-described embodiment, when the upper limit rotation speed Ne _{LIM_H} is set by the rotation speed upper limit value setting unit 4a, the upper limit rotation speed Ne for _each of the accelerator operation amount A _PS , the brake fluid pressure B _RK , and the coolant temperature W _{TS. Although} a configuration in which only one of _them is selected as the final upper limit rotation speed Ne _{LIM_H after} setting _{LIM_H} is _exemplified , the method of setting the final upper limit rotation speed Ne _{LIM_H} is not limited to this. The average value of the individual upper limit rotational speeds Ne _{LIM_H} for each of the accelerator operation amount A _PS , the brake fluid pressure B _RK , and the cooling water temperature W _TS may be _used as the final upper limit rotational speed Ne _{LIM_H} or individual upper limit rotational speeds. define the function of Ne _{LIM_H} may calculate a final upper limit rotation speed Ne _{LIM_H.}

  In the above-described embodiment, an example in which the upper limit control is incorporated in the engine control device 1 that performs the torque base control based on the magnitude of torque required for the engine 10 is illustrated. Is not an essential element. In the upper limit value control, if the configuration is such that at least the upper limit value of the actual rotational speed Ne is controlled according to the driver's intention to start, the rapid increase in the actual rotational speed Ne that can occur immediately after the engine 10 is started ( Acceleration according to the intention to start can be obtained while suppressing the rise). The same applies to the opening degree restriction control, and as long as the restriction on the throttle opening degree is released based on at least the intake system pressure of the engine 10 or the advance margin of the ignition timing, The same effect is produced.

Further, in the opening degree restriction control in the above-described embodiment, the throttle opening degree θ _TH is exemplified based on the upper limit value S _LIM calculated by the upper limit area calculation unit 6b. Is not limited to this. For example, the throttle opening degree θ _TH may be limited by setting an opening degree limiting coefficient having a value less than 1.0 and multiplying this by the target throttle area S. Alternatively, instead of selecting the smaller one of the target throttle area S and the upper limit value S _LIM , the throttle opening θ _TH may be limited using an intermediate value or an average value of these values. Further, the parameter to be restricted is not limited to the target throttle area S alone. By at least limiting the parameter that is the control target value of the throttle opening θ _TH or the parameter that correlates to the parameter, the same effect as the above-described embodiment can be obtained.

Further, the idle stop condition, the idle operation condition, the restart condition, the start condition and the end condition of the upper limit control described in the above embodiment may be changed as appropriate according to the embodiment.
In the above-described embodiment, the control action at the time of restart from the idle stop state has been mainly described. However, the application target of the above upper limit control is not limited to this, for example, the key start of the engine 10 by manual operation Sometimes it can be done.

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 Idle stop control part 3 Required torque calculating part 4 Torque upper limit value calculating part 5 Target torque calculating part 6 Throttle opening restriction part at the time of start 6a Target area calculating part (opening calculating means)
6b Upper limit area calculation part (limitation means)
6c Target air amount calculation unit (air amount calculation means)
7 Opening restriction release unit 7a Volume efficiency coefficient calculation unit (volume efficiency coefficient calculation means)
7b Target pressure calculation part (pressure calculation means)
7f Condition determination unit (release means)
10 Engine 34 Airflow sensor 35 Cooling water temperature sensor 36 Engine rotation speed sensor 37 Intake manifold pressure sensor

Claims (8)

In an engine control device that controls the operation at the start of an engine mounted on a vehicle,
Opening calculation means for calculating a target opening that is a control target value of the throttle opening of the engine;
Limiting means for limiting the target opening at the time of starting the engine to an upper limit value or less;
Release means for releasing the restriction of the target opening when the rate of change of the rotational speed of the engine is less than a predetermined rate of change,
The release means is configured to provide the target when the advance margin until the ignition timing at which the engine generates maximum actual torque is equal to or less than a predetermined value and the rate of change of the rotational speed of the engine is less than a predetermined rate of change. An engine control device that releases the restriction of the opening degree . It said releasing means, based on the intake system pressure of the engine, and cancels the limit of the target opening performed by the limiting means, the engine control apparatus according to claim 1, wherein. An air amount calculating means for calculating a target air amount that is a target value of the air amount introduced into the cylinder of the engine;
Pressure calculating means for calculating a target pressure corresponding to the intake system pressure when the target air amount is obtained by the engine;
The engine control apparatus according to claim 2 , wherein the release means releases the restriction on the target opening when the target pressure is equal to or greater than an actual measured value of the intake system pressure. A volume efficiency coefficient calculating means for calculating a volume efficiency coefficient corresponding to a value obtained by standardizing the volume efficiency of the engine based on the intake system pressure;
4. The engine control device according to claim 3 , wherein the pressure calculation means calculates the target pressure based on the target air amount and the volumetric efficiency coefficient. It said limiting means, and sets the upper limit value based on the coolant temperature of the engine, the engine control apparatus according to any one of claims 1-4. The limiting means separately sets a first upper limit value that is the upper limit value during cranking until the engine is started and a second upper limit value that is the upper limit value after the engine is started. The engine control device according to any one of claims 1 to 5 , wherein The release means cancels the restriction on the target opening when the elapsed time after starting the engine exceeds a predetermined time, and the first time until the restriction is released when the engine is started from an idle stop state. than an hour, and sets shorter second time until release the restriction at the time of starting of the engine except for the starting from the idle stop state, to any one of claims 1 to 6 The engine control device described. Said releasing means, when stopping the engine, and cancels the limit of the target opening performed by the limiting means, the engine control apparatus according to any one of claims 1-7.

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