JP2013139749A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve calculation accuracy of an air amount sucked into an engine in a range from motoring time to a post-starting time, in an engine control device.SOLUTION: An embodiment of the present invention is provided with: a pressure detection means 34 provided at an intake system of an engine 10, for detecting a downstream pressure of a throttle valve part; a motor 30 capable of rotating and driving the engine 10 to a predetermined speed or more at which the downstream pressure becomes lower than the atmospheric pressure; an air amount calculation means 2C for calculating an air amount Ec introduced into a cylinder 19 of the engine 10 on the basis of the downstream pressure and a rotation speed Ne of the engine 10 during engine starting when the engine 10 is rotated and driven by the motor 30; and an output control means 3 for controlling the output of the engine 10 on the basis of the air amount Ec calculated by the air amount calculation means 2C.

Description

  The present invention relates to an engine control device that controls output based on the amount of air sucked into a cylinder.

  Conventionally, in an engine control device mounted on a vehicle, an intake air amount sucked into a cylinder is calculated as needed as a parameter for setting a fuel injection amount and an ignition timing. The method of calculating the intake air amount is roughly classified into a speed density method and a mass flow method.

  The speed density method is a method of calculating the intake air density from the pressure in the intake pipe and calculating the intake air amount from the density and the engine rotation speed, as described in Patent Document 1, for example. In this method, the intake air amount is calculated based on the detection value of the pressure sensor provided on the downstream side of the intake manifold and the throttle valve portion. Since the sensor for detecting the pressure in the intake pipe can be built in the wall surface of the intake pipe, there is an advantage that it is difficult to cause an intake resistance and hardly affects the intake characteristics of the engine. However, there are cases where the intake pipe pressure is not necessarily proportional to the intake air amount, and the detection value of the sensor is affected by the intake pulsation, which makes it difficult to improve the calculation accuracy of the intake air amount.

  On the other hand, the mass flow method is a method of calculating the intake air amount by directly detecting the amount of air flowing through the intake pipe, as described in Patent Document 2, for example. In this method, the intake air amount is calculated based on the detection value of the air flow sensor installed on the upstream side of the intake manifold. Therefore, there is an advantage that an accurate intake air amount with little influence of intake pulsation can be grasped. However, since the intake air flow rate actually introduced into the cylinder changes with a delay with respect to the detection value of the sensor, there is a disadvantage that the response is slightly inferior.

JP 2003-106203 A Japanese Patent Laid-Open No. 9-291846

  By the way, in the engine control device that calculates the intake air amount by the mass flow method, the value obtained by performing a predetermined delay process on the sensor detection value in consideration of the intake response delay as described above is the actual intake air amount. Calculated. However, at the time of cranking for starting the stopped engine, the rotational speed by cranking is relatively low and the intake air amount is extremely small, so it is difficult to calculate an accurate value of the intake air amount.

  On the other hand, since the intake system pressure at the time of normal cranking is almost atmospheric pressure, the amount of air introduced into the cylinder at the time of cranking roughly depends on the rotational speed of the engine (cranking rotational speed). Therefore, a method has been proposed in which the intake air amount during cranking is set to a value corresponding to the rotational speed of the engine, and calculation of the intake air amount based on the sensor detection value is started after the cranking is completed.

  However, the actual intake air amount sucked into the cylinder during cranking of the engine may not be a value corresponding to the cranking rotation speed. For example, in a hybrid electric vehicle having a power mechanism that combines an internal combustion engine (engine) and an electric motor (motor), a stopped engine may be driven by a motor to start the engine. At this time, the engine speed may be increased by the motor to a higher rotation range than during normal cranking, and the intake system pressure gradually decreases even in a state where the engine does not rotate independently, and enters the cylinder. The amount of inhaled air is reduced. As a result, the difference between the estimated value of the intake air amount immediately before the engine starts and the value of the intake air amount calculated based on the sensor detection value immediately after the engine starts increases, and the engine control immediately after the engine starts. There is a risk that the performance will be reduced.

One of the purposes of the present invention was devised in view of the above-described problems, and relates to an engine control device, and is to improve the calculation accuracy of the amount of air taken into the engine from the time of motoring to the start of the engine. .
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 includes a pressure detection unit that is provided in an intake system of an engine and detects a downstream pressure of a throttle valve portion. A motor capable of rotationally driving the engine up to a predetermined speed at which the downstream pressure is lower than the atmospheric pressure; The engine further includes an air amount calculating means for calculating the amount of air introduced into the cylinder of the engine based on the downstream pressure and the rotational speed of the engine when the engine is rotatingly driven by the motor. Furthermore, output control means for controlling the output of the engine based on the air amount calculated by the air amount calculation means is provided.
The air amount calculating means may calculate the air amount when the downstream pressure is equal to or lower than a predetermined pressure lower than the atmospheric pressure due to the operation of the motor. Alternatively, when the rotational speed of the motor is equal to or higher than the predetermined speed, the air amount calculation means may calculate the air amount.

  (2) Moreover, it is preferable to provide a pressure ratio calculating means for calculating a pressure ratio of the downstream pressure to the upstream pressure of the throttle valve portion of the intake system based on the downstream pressure detected by the pressure detecting means. In this case, it is preferable that the air amount calculation means calculates the air amount at the time of starting the engine based on the pressure ratio and the rotation speed.

  (3) Further, based on the pressure ratio and the rotational speed, the volumetric efficiency of the engine is standardized by an intake system pressure (for example, intake manifold pressure, throttle section downstream pressure, throttle section upstream pressure, etc.). It is preferable to provide a volume efficiency coefficient calculating means for calculating a corresponding volume efficiency coefficient. In this case, it is preferable that the air amount calculating means calculates the air amount at the time of starting the engine based on the volumetric efficiency coefficient.

(4) It is preferable that a flow rate detection means for detecting the intake flow rate is provided in the intake system. In this case, the air amount calculation means calculates the air amount based on the downstream pressure and the rotational speed of the engine during the non-self-rotation of the engine, and the intake air flow rate during the self-rotation of the engine. It is preferable to calculate the air amount based on this.
In other words, it is preferable that the air amount calculation means switches a parameter serving as a basis for the calculation of the air amount depending on whether or not the engine is rotating independently. The parameter switching conditions may be changed. For example, it may be switched according to the intake system pressure, or may be switched according to the rotational speed of the engine or the rotational speed of the motor.

  (5) Moreover, it is preferable that the said motor rotates the engine until the said rotational speed becomes more than predetermined speed at least at the time of the said engine starting. Further, the output control means calculates a fuel injection amount based on the air amount, stops fuel injection when the rotational speed is less than the predetermined speed, and stops fuel injection when the rotational speed is equal to or higher than the predetermined speed. It is preferable to have a fuel injection control means for performing injection.

  In the disclosed engine control device, when the engine is driven to rotate by a motor, the air amount is calculated based on the downstream pressure and the rotational speed, and the engine control device relies on means for detecting the intake air flow rate (for example, an air flow sensor). The air amount can be calculated accurately. This makes it possible to appropriately control the fuel injection amount and ignition timing immediately after the engine is started, and improve the engine startability and rotational stability.

It is a figure which illustrates the block configuration of the control apparatus of the engine which concerns on one Embodiment, and the structure of the engine to which this control apparatus was applied. 6 is a graph illustrating the relationship between an actual rotational speed Ne and a pressure ratio R _PRS and a volume efficiency coefficient K _{map according} to the present control device. 5 is a graph for explaining a control action in the first start mode by the present control device, in which (a) is an actual engine speed Ne, (b) is an intake manifold pressure P _IM , and (c) is a time of filling efficiency Ec. Each variation is shown. It is a graph for demonstrating the control effect | action at the time of the 2nd starting mode by this control apparatus, (a) is the actual rotational speed Ne of an engine, (b) is intake manifold pressure _PIM , (c) is a time-dependent change of filling efficiency Ec. Respectively.

  An engine control apparatus 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. Drive system]
The engine control device of the present embodiment is applied to a parallel hybrid electric vehicle (HEV) using the engine 10 and the motor 30 shown in FIG. 1 as drive sources. The engine 10 is, for example, a multi-cylinder gasoline engine, and a transmission 28 incorporating a clutch 28a and a gear box 28b is connected to an output shaft thereof. In addition, drive wheels 29 are connected to the transmission 28 via a drive shaft, a differential gear, or the like.

  The motor 30 is a motor generator that has both a function as an electric motor and a function as a generator, and is connected in parallel with the engine 10 to the gear box 28b. When the motor 30 functions as an electric motor, the motor 30 rotates upon receiving power supplied from a battery (not shown) and transmits driving force to the transmission 28. On the other hand, when the motor 30 functions as a generator, regenerative power generation is performed using the driving force transmitted from the engine 10 or the rotational force input from the driving wheel 29 side to charge the battery.

  The driving force generated by the motor 30 acts to assist the rotation of the engine 10 that transmits the driving force to the drive wheels 29. Further, when the engine 10 is in a stopped state, the vehicle travels only with the driving force generated by the motor 30. When the clutch 28 a of the transmission 28 is engaged, the driving force of the motor 30 is transmitted to both the driving wheel 29 and the engine 10.

  Thus, rotating the engine 10 with the driving force of the motor 30 is referred to as “motoring”. The motoring is used, for example, when the engine 10 is running such that the output of the engine 10 is insufficient, or when cranking to start the stopped engine 10. The hybrid electric vehicle equipped with the engine control device of the present embodiment can start the engine 10 not only when the vehicle is stopped but also when the vehicle is running.

[1-2. engine]
The internal configuration of the engine 10 shown in FIG. 1 is one of a plurality of cylinders built in the engine 10. The piston 16 is provided so as to be slidable back and forth along the inner peripheral surface of a cylinder 19 formed in a hollow cylindrical shape. The space surrounded by the upper surface of the piston 16 and the inner peripheral surface and top surface of the cylinder 19 functions as a combustion chamber 26 of the engine.

  The lower portion of the piston 16 is connected to a crank arm having a central axis that is eccentric from the axis of the crankshaft 17 via a connecting rod. Thereby, the reciprocating motion of the piston 16 is transmitted to the crank arm and converted into the rotational motion of the crankshaft 17.

  An intake port 11 for supplying intake air into the combustion chamber 26 and an exhaust port 12 for discharging exhaust gas after combustion in the combustion chamber 26 are formed in the top surface of the cylinder 19. An intake valve 14 and an exhaust valve 15 are provided at the end of the intake port 11 and the exhaust port 12 on the combustion chamber 26 side. The operations of the intake valve 14 and the exhaust valve 15 are individually controlled by a variable valve mechanism 27 provided in the upper part of the engine 10.

  The variable valve mechanism 27 is a mechanism that changes 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. A spark plug 13 is provided at the top of the cylinder 19 with its tip projecting toward the combustion chamber 26. The ignition timing by the spark plug 13 is controlled by the engine control device 1 described later.

[1-3. Intake and exhaust system]
An injector 18 for injecting fuel is provided in the intake port 11. The amount of fuel injected from the injector 18 is 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 port 11 of each cylinder 19, 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) of the throttle valve 23. The throttle opening is controlled by the engine control device 1.

  An intake passage 24 is connected further upstream of the throttle body 22, and 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 each cylinder 19 of the engine 10 via the intake passage 24 and the intake manifold 20.

[1-4. Detection system]
The crankshaft 17 of the engine 10 is provided with an engine rotation speed sensor 31 that detects the rotation angle. The amount of change (angular velocity) per unit time of the rotation angle is proportional to the actual rotation speed Ne (actual rotation number per unit time) of the engine 10. Therefore, the engine rotation speed sensor 31 has a function of acquiring the actual rotation speed Ne of the engine 10. The actual rotation speed Ne may be calculated inside the engine control device 1 based on the rotation angle detected by the engine rotation speed sensor 31.

An atmospheric pressure sensor 32 is provided inside the engine control device 1 or at an arbitrary position of the vehicle. The atmospheric pressure sensor 32 detects atmospheric pressure (atmospheric pressure) _BP . This atmospheric pressure _BP corresponds to the pressure at the inlet of the intake passage 24 (pressure upstream of the air filter 25).
In addition, an accelerator opening sensor 33 that detects the amount of depression of the accelerator pedal (accelerator opening A _PS ) is provided at an arbitrary position of the vehicle (for example, in the vicinity of the accelerator pedal). The accelerator opening A _PS is a parameter corresponding to the driver's acceleration request, that is, corresponds to an output request to the engine 10.

An intake manifold pressure sensor 34 that detects intake manifold pressure P _IM (pressure corresponding to the pressure in the surge tank 21) is provided downstream of the throttle valve 23. On the other hand, an air flow sensor 35 for detecting the intake air flow rate Q is provided in the intake passage 24 upstream of the throttle valve 23. Information on the actual rotational speed Ne, the atmospheric pressure B _P , the accelerator opening A _PS , the intake manifold pressure P _IM , and the intake air flow rate Q acquired by the various sensors 31 to 35 is transmitted to the engine control device 1.

Note that the atmospheric pressure B _P detected by the atmospheric pressure sensor 32 and the intake manifold pressure P _IM detected by the intake manifold pressure sensor 34 are volume efficiency which is an evaluation index of the intake performance in accordance with the volume efficiency of the engine in the engine control device 1. Used for calculating the coefficient K _map . The atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 function as pressure detection means for detecting the intake system pressure of the engine 10. In particular, the intake manifold pressure sensor 34 functions as pressure detection means for detecting the downstream pressure of the throttle valve 23 part. The air flow sensor 35 functions as a flow rate detection unit that detects the intake flow rate Q.

[2. Control device configuration]
A vehicle equipped with the engine 10 is provided with an engine control device 1 (Engine Electronic Control Unit). The engine control device 1 is configured as, for example, an LSI device or a built-in electronic device in which a microprocessor, ROM, RAM, and the like are integrated, and is connected to a communication line of an in-vehicle network provided in the vehicle. Note that various known electronic control devices such as a brake control device, a transmission control device, a vehicle stability control device, an air conditioning control device, and an electrical component control device are communicably connected to each other on the in-vehicle network. An electronic control device other than the engine control device 1 is called an external control system, and a device controlled by the external control system is called an external load device.

  The engine control device 1 is an electronic control device that comprehensively 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, and the amount of air supplied to each cylinder 19 of the engine 10. The fuel injection amount, the ignition timing of each cylinder 19 and the like are controlled. Here, torque base control based on the magnitude of torque required for the engine 10 is performed. Specific control targets 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 of the throttle valve 23, and the like.

  As shown in FIG. 1, an engine speed sensor 31, an atmospheric pressure sensor 32, an accelerator opening sensor 33, an intake manifold pressure sensor 34, and an airflow sensor 35 are connected to the input side of the engine control device 1. Further, an ignition plug 13, an injector 18, a throttle valve 23, a variable valve mechanism 27, and the like, which are torque base control targets, are connected to the output side of the engine control device 1.

The engine control apparatus 1 calculates a volumetric efficiency coefficient K _map as an index value for evaluating the intake performance of the engine 10, and estimates an actual air amount introduced (or introduced) into the cylinder 19 based on this. To control the output torque. The actual air amount (for example, actual intake air amount, actual charging efficiency, etc.) calculated based on the volumetric efficiency coefficient K _map is used for controlling the fuel amount injected from the injector 18 and the ignition timing at the spark plug 13. .

In the engine control apparatus 1, two types of methods are used as calculation methods for _obtaining the volumetric efficiency coefficient K _map . The first method is a method using a pressure ratio that is a ratio of the downstream pressure to the upstream pressure of the throttle valve 23 portion, and the second method is a method using the intake air flow rate Q detected by the air flow sensor 35. These methods are switched according to the operating state of the engine 10.

  As shown in FIG. 1, the engine control device 1 is provided with an intake air amount calculation unit 2, an output control unit 3, and a start control unit 4. Each of these elements may be realized by an electronic circuit (hardware), may be programmed as software, or some of these functions are provided as hardware, and the other part is software. It may be a thing.

[2-1. Intake air amount calculation unit]
The intake air amount calculation unit 2 calculates the actual filling efficiency Ec based on the volumetric efficiency coefficient K _map . The actual filling efficiency Ec is a parameter corresponding to the amount of air actually introduced into the cylinder 19. Further, the volumetric efficiency coefficient K _map is obtained by standardizing the volumetric efficiency Ev with respect to the intake system pressure. The intake system pressure as referred to herein means a pressure detected by the intake system of the engine 10, for example, downstream pressure of the intake manifold pressure P _IM and the throttle valve 23, the upstream pressure, and the like atmospheric B _P.

The intake air amount calculation unit 2 includes a pressure ratio calculation unit 2A, a volumetric efficiency coefficient calculation unit 2B, an actual charging efficiency calculation unit 2C, and a second actual charging efficiency calculation unit 2D.
The pressure ratio calculation unit 2A (pressure ratio calculation means) calculates the ratio of the downstream pressure to the upstream pressure of the throttle valve 23 as the pressure ratio R _PRS based on the intake system pressure of the engine 10. The pressure ratio R _PRS of the present embodiment, the intake manifold pressure P _IM detected by the intake manifold pressure sensor 34, is calculated based on the atmospheric pressure B _P detected by the atmospheric pressure sensor 32. The value of the pressure ratio R _PRS calculated here is transmitted to the volumetric efficiency coefficient calculation unit 2B. Note that obtains what from atmospheric B _P by subtracting the pressure loss of the intake passage 24 as the upstream pressure of the throttle valve 23 may be calculated the ratio of the intake manifold pressure P _IM to this as the pressure ratio R _PRS.

The volumetric efficiency coefficient computing unit 2B (volumetric efficiency coefficient computing means) computes the volumetric efficiency coefficient K _map based on the actual rotational speed Ne of the engine 10 and the pressure ratio R _PRS . Here, a correspondence map, a mathematical expression, a relational expression, and the like of the actual rotational speed Ne and the pressure ratio R _PRS and the volumetric efficiency coefficient K _map are set in advance, and the volumetric efficiency coefficient computing unit 2B is based on such a relationship. Calculate the volumetric efficiency coefficient K _map . The value of the volume efficiency coefficient K _map calculated here is transmitted to the actual filling efficiency calculation unit 2C. As a _map for _{obtaining the} volumetric efficiency coefficient K _map , for example, a map as shown in FIG. 2 is used.

Incidentally, the volumetric efficiency Ev of the engine 10 becomes smaller value as the intake manifold pressure P _IM decreases. However, the relationship between the volumetric efficiency Ev and intake manifold pressure P _IM is not necessarily linear, the variation of the volumetric efficiency Ev (gradient change) is large enough to decrease the intake manifold pressure P _IM when changing the intake manifold pressure P _IM . This not only push-friendliness of the intake air of the cylinder 19 the value of the volumetric efficiency Ev is determined by the intake manifold pressure P _IM, enters into the intake air of the cylinder 19 which is determined according to the operating state of the variable valve mechanism 27 This is because it changes under the influence of ease.

On the other hand, since the volumetric efficiency factor K _map is a standardized value for the intake system pressure, little affected by the push-friendliness of the intake air by the intake manifold pressure P _IM. Thus, by using a volumetric efficiency coefficient K _map in place of the volumetric efficiency Ev, it is possible to remove the influence of the intake manifold pressure P _IM from evaluation of the intake performance of the engine 10.

The actual charging efficiency calculation unit 2C (air amount calculation means) calculates the actual charging efficiency Ec when a predetermined pressure ratio use condition is satisfied. Actual charging efficiency Ec is calculated on the basis of the volumetric efficiency coefficient K _map and intake manifold pressure P _IM. Alternatively, the actual charging efficiency Ec is calculated by correcting the intake air density on the volumetric efficiency Ev. The value of the actual filling efficiency Ec calculated here is transmitted to the output control unit 3.

The predetermined pressure ratio use conditions are, for example, the conditions shown in [1] to [3] below, and when all these conditions are satisfied, the actual filling efficiency Ec is calculated based on the volumetric efficiency coefficient K _map. . It can be said that this pressure ratio use condition is a condition for determining whether or not the engine 10 is being driven by the motor 30. The start determination rotational speed in condition 2 is a rotational speed at which the engine 10 being started is considered to be rotating independently, and may be a preset constant (for example, 200 [rpm], for example). However, the values may be set according to various starting conditions such as the outside air temperature, the outside air pressure, and the engine coolant temperature.
[1] The motor 30 is driving the engine 10. [2] The actual rotational speed Ne of the engine 10 is equal to or less than the start determination rotational speed. [3] The engine 10 is not rotating independently.

On the other hand, the second actual charging efficiency calculating unit 2D (air amount calculating means) calculates the actual charging efficiency Ec based on the intake flow rate Q when the pressure ratio use condition is not satisfied. Examples of situations where the pressure ratio use condition is not satisfied include a state where the engine 10 is rotating independently, a state where the motor 30 is not starting the engine 10, and the like. The second actual filling efficiency calculation unit 2D calculates a detected filling efficiency Ec _(r) corresponding to the actual filling efficiency Ec at the position where the airflow sensor 35 is provided.

The value of the actual filling efficiency Ec corresponding to the amount of air introduced into the cylinder 19 varies slightly behind the detected filling efficiency Ec _(r) obtained here. That is, the actual filling efficiency Ec is the amount of air actually introduced into the cylinder 19 and corresponds to the air amount after the intake response delay, whereas the detected filling efficiency Ec _(r) is the intake response delay. Corresponds to the previous air volume.

Therefore, the second actual filling efficiency calculation unit 2D calculates the current value Ec _(n) of the actual filling efficiency Ec based on the detected filling efficiency Ec _(r) and the previous value Ec _(n-1) of the actual filling efficiency Ec. To do. This current value Ec _(n) is delayed in response to a predetermined amount f (Ec _(n-1) , Ec _(r) ) expressed as a function of the detection filling efficiency Ec _(r) and the previous value Ec _(n-1). It is assumed that. Various methods for giving a response delay are conceivable. When a primary response delay is given, the current value Ec _(n) of the actual charging efficiency Ec can be obtained based on, for example, Equation 1. T in Equation 1 is a time constant for giving a change corresponding to the intake response delay to the value of the actual charging efficiency Ec.

In the calculation of Equation 1, the ratio of the current value K _{map (n)} to the volumetric efficiency coefficient K _{map (n-1)} in the previous calculation cycle is a predetermined amount f (Ec _(n-1) , Ec _(r) ) Is multiplied by. The value of this ratio (K _{map (n)} / K _{map (n-1)} ) is always 1 when the volumetric efficiency coefficient K _map of the engine 10 does not change, and the current actual charging efficiency Ec _(n) is calculated. Does not affect. On the other hand, when the detected charging efficiency Ec _(r) greatly fluctuates due to changes in the valve lift amount and valve timing of the intake valve 14 and exhaust valve 15, the value of this ratio increases as the volumetric efficiency coefficient K _map increases. On the contrary, the value of this ratio decreases as the volumetric efficiency coefficient K _map decreases. Thereby, the followability of the actual filling efficiency Ec _(n) with respect to the fluctuation of the detected filling efficiency Ec _(r) is improved, and the convergence time is shortened.

Thus, in the intake air amount calculation unit 2, the actual charging efficiency Ec obtained by the actual charging efficiency calculation unit 2 </ b> C is transmitted to the output control unit 3 when the pressure ratio use condition is satisfied. When the pressure ratio use condition is not established, the actual charging efficiency Ec _(n) obtained by the second actual charging efficiency calculation unit 2D is transmitted to the output control unit 3. As a result, during motoring when the engine 10 is started by the motor 30, the actual charging efficiency Ec based on the intake system pressure is used for output control of the engine 10, and in other cases, actual charging based on the intake air flow rate is used. Efficiency Ec _(n) will be used.

[2-2. Output control unit]
The output control unit 3 (output control means) controls the output of the engine 10 after starting based on the actual charging efficiency Ec calculated by the intake air amount calculation unit 2. Here, the amount of fuel injected from the injector 18 and the injection timing, the ignition timing at the spark plug 13, the opening of the throttle valve 23, and the like are controlled. The fuel injection amount during the startup of the engine 10 and the opening of the throttle valve 23 are controlled by a start control unit 4 described later.

The output control unit 3 is provided with a memory that stores not only the value of the actual filling efficiency Ec _{(n) in} the current calculation cycle but also the value of the actual filling efficiency Ec up to a predetermined time as history information. The output control unit 3 calculates a target charging efficiency Ec _TGT corresponding to the target value of the air amount to be introduced into the cylinder 19 based on the accelerator opening A _PS and obtains the actual charging efficiency Ec and the target charging efficiency Ec _TGT . Based on this, the intake air amount and the fuel injection amount are controlled.
For example, in the intake air amount control, the flow rate of the intake air passing through the throttle valve 23 is calculated according to the atmospheric pressure B _P and the intake manifold pressure P _IM , and the target flow rate calculated from the target charging efficiency Ec _TGT and the intake air flow rate are calculated. Based on the above, the throttle opening is controlled.

In the fuel injection amount control, the injection amount for each cylinder 19 is controlled based on the actual charging efficiency Ec and the target charging efficiency Ec _TGT . Here, the pulse width of the excitation signal is set so that the amount of fuel injected from the injector 18 becomes an amount corresponding to the actual filling efficiency Ec and the target filling efficiency Ec _TGT , and the excitation signal is output to the injector 18. Is done. The pulse width of the excitation signal is calculated from the desired air-fuel ratio and the actual charging efficiency Ec or the target charging efficiency Ec _TGT using a predetermined arithmetic expression or control map set in advance.

In the ignition timing control, the retard amount based on the optimum ignition timing (MBT, Minimum spark advance for Best Torque) at which the maximum torque is generated at the actual charging efficiency Ec and the target charging efficiency Ec _TGT depends on the engine speed Ne. Is set. Thereafter, a control signal is output to the spark plug 13 at a timing at which the set retard amount is reached.

[2-3. Start control unit]
The start control unit 4 performs control for starting the stopped engine 10 with the motor 30. Here, the transmission 28, the motor 30 and the like are controlled when a predetermined start control start condition is satisfied. The start control start condition is, for example, when the ignition key switch is operated to the start position while the vehicle is stopped, or when there is a request for starting the engine from the external load device while the engine 10 is stopped. This is established when the battery charge is insufficient.

The hybrid electric vehicle is provided with a first start mode for performing cranking and a second start mode for performing motoring. These start modes are selected according to the operation input from the driver, the driving state of the vehicle, and the like.
The first start mode is a mode in which fuel injection is performed while the engine 10 is rotated by an external force to rotate independently. That is, in the first start mode, the motor 30 is rotationally driven while the clutch 28a of the transmission 28 is in the connected state. Furthermore, while the engine 10 is being rotated, fuel injection from the injector 18 and ignition by the spark plug 13 are performed together. Thereafter, when the engine 10 rotates independently, the first start mode ends.

  The first start mode is a mode in which cranking is performed using the motor 30 instead of the starter motor of a vehicle whose drive source is not hybrid. The rotation speed of the motor 30 in the first start mode is relatively low, and is set to about 200 [rpm], for example. The first start mode is canceled when the actual rotational speed Ne exceeds a predetermined self-sustained rotational speed, and shifts to a normal operation mode.

  On the other hand, the second start mode is a mode in which a process of rotating the engine 10 with an external force and a process of performing fuel injection are separated. That is, in the second start mode, the motor 30 is rotationally driven at a high speed while the clutch 28a of the transmission 28 is kept in the connected state. At this time, the rotation speed of the motor 30 increases to a higher rotation speed than in the first start mode. Thereafter, fuel injection is performed only when the actual rotational speed Ne of the engine 10 exceeds a predetermined start determination rotational speed, the second start mode is canceled, and the operation mode is shifted to the normal operation mode.

  When the second start mode is released, normal fuel injection from the injector 18 and ignition by the spark plug 13 are started. The start determination rotational speed is relatively high, and is set to, for example, about 1500 [rpm]. As described above, the second start mode is a mode in which fuel is not injected while the motor 30 is being driven (motoring period).

  In the present embodiment, the actual charging efficiency Ec is calculated by the intake air amount calculation unit 2 during the execution period regardless of the type of the start mode. At least when the start mode is performed, the above-described conditions for using the pressure ratio are all satisfied, and therefore the actual charging efficiency Ec based on the pressure ratio is calculated. On the other hand, when the start mode ends, any of the pressure ratio use conditions is not satisfied, and the actual air-based charging efficiency Ec is calculated.

[3. Action]
The control action by this control apparatus will be described. FIG. 3 is an example showing the behavior in the first start mode, and FIG. 4 is an example showing the behavior in the second start mode. Moreover, it is each: (a) the change over time of the actual rotational speed Ne of FIG 3, 4, (b) is a time variation of the intake manifold pressure P _IM detected by the intake manifold pressure sensor 34, (c) the actual The change with time of the filling efficiency Ec is shown. Before time t ₁ , the vehicle is stopped and the engine 10 is also stopped, and the engine control mode is a so-called “engine mode”.

[3-1. First start mode]
When the ignition key switch at the time t ₁ in FIG. 3 is operated, the control mode is shifted from the "stalling mode" to the "first start-up mode", cranking of the engine 10 by the motor 30 is started. In the first start mode, the motor 30 is driven at a relatively low speed, and the actual rotational speed Ne of the engine 10 is set to around a predetermined cranking rotational speed. In addition, fuel injection from the injector 18 is performed in accordance with the stroke in each cylinder 19 and ignition by the spark plug 13 is performed.

Initial combustion of the engine 10, through the complete explosion, the actual rotational speed Ne exceeds the self-rotation speed time t _2, the the first starting mode is canceled, the normal operation mode is started. For example, when the rotational speed feedback control is started here, as shown in FIG. 3A, the actual rotational speed Ne of the engine 10 increases once and then converges to the idling rotational speed.
Intake manifold pressure P _IM detected by the intake manifold pressure sensor 34 in the first start-up mode, as shown in FIG. 3 (b), it varies every time each cylinder 19 is sucked air. However, since the actual rotational speed Ne is relatively slow, the variation of the intake manifold pressure P _IM is slight, the same pressure substantially atmospheric pressure.

Further, the pressure ratio use condition is satisfied during the first start mode. Therefore, the actual charging efficiency Ec calculated by the intake air amount calculation unit 2 is a value based on the intake system pressure. That is, the pressure ratio R _PRS is calculated based on the intake manifold pressure P _IM and the atmospheric pressure B _P , and the volume efficiency coefficient K _map is calculated based on the pressure ratio R _PRS and the actual rotational speed Ne, and the volume efficiency coefficient K _map and actual charging efficiency Ec is computed based on the intake manifold pressure P _IM. The value of the actual filling efficiency Ec during the cranking period is substantially constant as shown by the solid line in FIG.

  In addition, the broken line in FIG.3 (c) is a graph which shows the comparative example at the time of setting the value of the actual filling efficiency Ec at the time of starting to the predetermined value according to the actual rotational speed Ne. The predetermined value here is a value of the charging efficiency corresponding to the maximum amount of air that can be introduced into the cylinder 19 when the throttle opening is fully opened at the actual rotational speed Ne at that time. The solid line graph almost coincides with the broken line graph, that is, the value of the actual charging efficiency Ec calculated by the intake air amount calculation unit 2 is almost the same as the actual charging efficiency Ec set at the time of conventional engine starting. I understand that.

[3-2. Second start mode]
When the ignition key switch at the time t ₃ in FIG. 4 is operated, the control mode is shifted from the "stalling mode" to the "second starting mode", the motoring of the engine 10 by the motor 30 is started. In the second start mode, the motor 30 is driven to a higher speed range than in the first start mode. At this time, fuel injection from the injector 18 and ignition by the spark plug 13 are not performed.

When the actual rotational speed Ne of the engine 10 exceeds the start threshold engine speed at time t _4, the second start mode is canceled, the normal operation mode is started. At this time, fuel injection from the injector 18 and ignition by the spark plug 13 are started.
Intake manifold pressure P _IM detected by the intake manifold pressure sensor 34 during the second start-up mode, decreases as the amount of air taken into the cylinder 19 of the engine 10 is increased. That is, during the second start mode, the actual rotational speed Ne increases to a relatively high rotational range, so that when air is sucked from the surge tank 21 into the cylinder 19, the replenishment of air through the intake passage 24 is in time. Whilst the intake manifold pressure P _IM as shown in FIG. 4 (b) gradually decreases.

Here, a graph when the value of the actual charging efficiency Ec in the second start mode is set by a conventional method is shown by a broken line in FIG. That is, this is a method of setting the value of the actual filling efficiency Ec to a predetermined value corresponding to the actual rotational speed Ne. In this case, since the predetermined value gradually increases as the actual rotational speed Ne increases, the intake performance of the engine 10 gradually increases in calculation. However, in actuality, as shown in FIG. 4B, the intake manifold pressure _PIM should be lower than the atmospheric pressure, so that the intake performance of the engine 10 should be lowered. That is, the conventional approach, intake manifold pressure P _IM is a preferably used in a state close to atmospheric pressure, it can be said that a method of calculation error increases in a state where the intake manifold pressure P _IM drops greater than atmospheric pressure .

On the other hand, in the intake air amount calculation unit 2, since the pressure ratio use condition is satisfied even during the second start mode, the actual charging efficiency Ec is a value based on the intake system pressure. Therefore, the value of the actual charging efficiency Ec, as shown by the solid line in FIG. 4 (c), decreases with the decrease of the intake manifold pressure P _IM, is as shown a behavior that matches the actual intake performance. Further, at time t ₄ after the second start mode has ended pressure ratio operating conditions is not satisfied, the actual charging efficiency Ec is a value which is based on the intake air flow rate.

At this time, since the value of the actual charging efficiency Ec has already decreased to a value that matches the actual intake performance, the time taken for the current value Ec _{(n) of the} actual charging efficiency Ec obtained by Equation 1 to converge is , Dramatically shortened. For example, according to the broken line graph shown in FIG. 4 (c), the time at which the value of the actual charging efficiency Ec _(n) converges is the time t ₅ before and after contrast, according to the solid line, the time t ₄ when Thus, a highly accurate convergence value can be obtained.

  The hatched portion surrounded by the solid line and the broken line in FIG. 4C shows the difference between the actual filling efficiency Ec obtained by the conventional calculation method and the actual filling efficiency Ec obtained by the above calculation method. is there. It can be seen that in the conventional method, the intake performance of the engine 10 is evaluated to be higher than the original intake performance by the amount corresponding to the area of the hatched portion.

In particular, since the error is large the actual charging efficiency Ec at time t ₄ when the fuel injection control and ignition timing control is started, the control amount of the fuel and the intake air immediately after starting becomes inaccurate in the conventional calculation method, aiming It is difficult to achieve a high air / fuel ratio. On the other hand, in the intake air amount calculation unit 2 described above, since an accurate actual charging efficiency Ec is required, the calculation accuracy of the fuel and intake air amount immediately after the start is improved.

[4. effect]
(1) In the engine control apparatus 1, the actual charging efficiency Ec is calculated based on the intake manifold pressure _PIM and the actual rotational speed Ne at the start of rotating the engine 10 with the motor 30. Accordingly, the actual charging efficiency Ec corresponding to the amount of air actually sucked into the cylinder 19 can be accurately calculated without depending on the intake flow rate Q detected by the air flow sensor 35. Therefore, it is possible to appropriately control the fuel injection amount, intake air amount, ignition timing, etc. immediately after the engine 10 is started, and startability and rotational stability can be improved.

(2) In the engine control apparatus 1 described above, the actual charging efficiency Ec during the start-up period of the engine 10 is calculated based on the pressure ratio R _PRS of the throttle valve 23 part. Thus, as compared with the case of using only intake manifold pressure P _IM, it is possible to improve the calculation accuracy of the actual charging efficiency Ec. Therefore, the controllability of the fuel injection amount, intake air amount, ignition timing, etc. immediately after the engine 10 is started can be improved.

(3) Furthermore, in the engine control apparatus 1 described above, the actual charging efficiency Ec is calculated using the volumetric efficiency coefficient K _map . Thereby, when the volumetric efficiency Ev of the engine 10 fluctuates, the amount of air actually taken into the cylinder can be accurately calculated.

For example, when the maximum valve lift amount and valve timing of the intake valve 14 and the exhaust valve 15 controlled by the variable valve mechanism 27 change, the volume efficiency Ev of the engine 10 varies greatly. Meanwhile, since the volumetric efficiency coefficient K _map a standardized volumetric efficiency Ev in the intake system pressure is used as the evaluation parameter of the intake performance, it can be grasped from entering ease of intake air without depending on the change of the intake manifold pressure P _IM, The calculation accuracy of the actual filling efficiency Ec can be increased. That is, it is possible to evaluate the intake performance of the engine 10 that is not influenced by the pressure change in the intake system.

  (4) In the engine control apparatus 1 described above, it is determined that one of the pressure ratio use conditions is that the engine 10 is not rotating independently, that is, when the engine 10 is not rotating independently. The actual charging efficiency Ec based on the system pressure is calculated. On the other hand, when the engine 10 starts to rotate independently, an actual charging efficiency Ec based on the intake air flow rate is calculated.

As described above, after the engine 10 is started, the influence of the intake pulsation can be eliminated by the calculation based on the intake flow rate Q, and an accurate value of the actual charging efficiency Ec can be obtained. Further, before the engine 10 is started, the influence of the intake response delay and the intake resistance can be eliminated by calculation based on the intake manifold pressure _PIM and the actual rotational speed Ne, and an accurate value of the actual charging efficiency Ec is obtained. be able to.

  (5) In the engine 10 of the present embodiment, fuel injection is started at the end of the second start mode in which the engine 10 is started. In this way, in the engine 10 of the type that does not perform fuel injection during the motoring period, when the actual charging efficiency Ec before engine startup is obtained based on the intake flow rate Q, as shown in FIG. The error of the actual filling efficiency Ec (the difference between the actual filling efficiency and the calculated filling efficiency) tends to increase at the time of starting the operation. On the other hand, in the engine control apparatus 1 described above, since such an error does not occur, the fuel injection amount and the intake air amount can be appropriately controlled.

[5. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.
For example, instead of the pressure ratio operating conditions in the above embodiments, or in addition, it may be determined that the intake manifold pressure P _IM is in a state of being reduced to a predetermined pressure or less, the rotational speed of the motor 30 is predetermined You may determine that it is below a rotational speed.

By using the intake manifold pressure P _IM, it is possible setting method of the conventional actual charging efficiency Ec is easily determined whether the applicable conditions. In addition, since the motor 30 is located upstream of the driving force transmission path when the engine 10 is started, the response to the operating state of the motor 30 can be improved by the determination based on the rotational speed of the motor 30. The engine speed sensor 31 can be omitted. The actual rotational speed Ne of the engine 10 may be grasped from the rotational speed of the motor 30 and the gear ratio in the transmission 28.

  Further, in the above-described embodiment, an example in which the actual charging efficiency Ec is calculated as an index value for grasping the amount of air sucked into the cylinder 19 is exemplified, but at least a parameter corresponding to the amount of air sucked into the cylinder 19 If the system is such that the engine output can be controlled by the engine control device 1 described above. Therefore, the configuration may be such that the volume efficiency Ev, the air volume, and the air mass are calculated instead of the actual filling efficiency Ec.

  In the above-described embodiment, the engine control apparatus 1 is applied to a hybrid electric vehicle including the engine 10 and the motor 30 as drive sources. However, the application target of the engine control apparatus 1 is not limited to this. For example, even if the vehicle does not have a vehicle driving motor 30 (non-hybrid vehicle), the engine control device 1 can be applied to any vehicle provided with a starter motor for cranking the engine 10. It is.

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 Intake air amount calculating part 2A Pressure ratio calculating part (pressure ratio calculating means)
2B Volume efficiency coefficient calculation unit (volume efficiency coefficient calculation means)
2C Actual filling efficiency calculation part (Air amount calculation means)
2D Second actual filling efficiency calculation unit (air amount calculation means)
3 Output controller (output controller, fuel injection controller)
4 start control unit 10 engine 30 motor 32 atmospheric pressure sensor 34 intake manifold pressure sensor (pressure detection means)
35 Air flow sensor (flow rate detection means)

Claims (5)

A pressure detecting means provided in the intake system of the engine for detecting the downstream pressure of the throttle valve portion;
A motor capable of rotationally driving the engine to a predetermined speed or higher at which the downstream pressure is lower than atmospheric pressure;
An air amount calculating means for calculating the amount of air introduced into the cylinder of the engine based on the downstream pressure and the rotational speed of the engine at the time of starting the engine that rotationally drives the engine with the motor;
An engine control device comprising: output control means for controlling the output of the engine based on the air quantity calculated by the air quantity calculation means. Pressure ratio calculating means for calculating the pressure ratio of the downstream pressure to the upstream pressure of the throttle valve portion of the intake system based on the downstream pressure detected by the pressure detecting means;
2. The engine control apparatus according to claim 1, wherein the air amount calculation means calculates the air amount at the time of starting the engine based on the pressure ratio and the rotation speed. Based on the pressure ratio and the rotation speed, comprising 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 by the intake system pressure,
3. The engine control device according to claim 2, wherein the air amount calculating means calculates the air amount at the time of starting the engine based on the volumetric efficiency coefficient. Provided with a flow rate detecting means provided in the intake system for detecting the intake flow rate;
The air amount calculation means is
While calculating the amount of air based on the downstream pressure and the rotational speed of the engine during non-self-sustaining rotation of the engine,
The engine control device according to any one of claims 1 to 3, wherein the air amount is calculated based on the intake air flow rate during the self-rotating rotation of the engine. The motor rotationally drives the engine until at least the rotational speed becomes a predetermined speed or higher at the time of starting the engine,
The output control means is
Fuel injection control means for calculating a fuel injection amount based on the air amount, stopping fuel injection when the rotational speed is less than the predetermined speed, and executing the fuel injection when the rotational speed is equal to or higher than the predetermined speed The engine control device according to any one of claims 1 to 4, characterized by comprising:

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