JP5776530B2 - Engine control device - Google Patents

Description

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

  As a control method for an engine mounted on a vehicle, torque base (torque demand) control for controlling intake air amount, fuel injection amount, ignition timing, etc. based on the magnitude of torque required for the engine is known. ing. In torque-based control, a target value of torque to be output by the engine is calculated based on the accelerator opening and the engine speed, and the engine operating state is controlled so that this target torque is obtained. Also, in vehicles equipped with external control systems such as automatic transmissions, auto cruise devices, and vehicle stabilizers, output requests from each external control system to the engine are converted into torque values and integrated in the engine control unit (engine ECU). The torque behavior of the engine is comprehensively controlled.

  Incidentally, the magnitude of the torque generated in the engine when the operating conditions are the same is proportional to the amount of intake air introduced into the cylinder. On the other hand, the amount of intake air actually introduced into the cylinder varies depending on engine specifications, environmental conditions, etc., even if the operating conditions are the same. Further, in the case of an engine equipped with a variable valve lift mechanism and a variable valve timing mechanism, if the operating state of the intake / exhaust valve is different, the intake air amount changes even if other operating conditions are the same. Therefore, in general torque-based control, the intake performance of the engine is evaluated based on the charging efficiency and volumetric efficiency at that time, and control according to the intake performance is performed.

  The charging efficiency is obtained by dividing the mass of intake air sucked in one cycle by the air mass corresponding to the stroke volume under standard atmospheric conditions. As a specific calculation method of the charging efficiency, there is a method of calculating based on an estimated value of the amount of air taken into the cylinder. For example, Patent Document 1 describes that a charging efficiency is calculated based on an engine rotational speed, an intake absolute pressure, an atmospheric absolute pressure, and the like regarding a control device for an internal combustion engine having a variable valve. In this technique, the flow rate of the air passing through the throttle valve unit is grasped using the pressure ratio between the intake absolute pressure and the atmospheric absolute pressure, and the charging efficiency in the reference state is calculated based on this.

  The volumetric efficiency is obtained by dividing the mass of the intake air sucked in one cycle by the air mass corresponding to the stroke volume under the same atmospheric conditions as the measurement. Since the volumetric efficiency is a ratio of two masses having the same atmospheric conditions, the volumetric efficiency can be obtained by dividing the volume of the intake air sucked in one cycle by the stroke volume. Or it is also possible to obtain | require by adding pressure correction and temperature correction to the value of the filling efficiency calculated by the above methods.

JP 2010-084549 A

  However, the conventional method for calculating the charging efficiency and volumetric efficiency as described above is to calculate the amount of intake air into the cylinder using the correlation between the flow rate of air passing through the throttle valve portion and the pressure ratio, The calculation accuracy of the charging efficiency and the volume efficiency depends on the calculation accuracy of the pressure ratio of the throttle valve section (the ratio of the downstream pressure to the upstream pressure). Therefore, when the pressure sensor is malfunctioning or when the detection accuracy is lowered, the estimation accuracy of the air amount is lowered, and there is a problem that accurate filling efficiency and volumetric efficiency cannot be obtained. In particular, when the pressure sensor fails, correct charging efficiency and volumetric efficiency cannot be calculated, and the controllability of the engine torque based on the fuel injection amount, ignition timing, etc. may be reduced.

  On the other hand, it is conceivable to prepare a method for estimating the amount of air introduced into the cylinder without using the pressure ratio as a fail-safe when the pressure sensor is malfunctioning. For example, it is conceivable that the correspondence between the opening of the throttle valve and the amount of air introduced into the cylinder at that opening is mapped or tabled and stored in the engine ECU or the like. However, in this case, it is necessary to prepare maps and tables corresponding to various engine operating conditions in advance, which increases the ROM capacity required for the engine ECU and increases the development costs.

  It is also conceivable to measure the amount of air using an air flow sensor. However, since the air flow sensor is installed at a position distant from the upstream side of the throttle valve, in a transient state where the intake air amount increases or decreases with the operation of the throttle valve, the actual intake air amount and the detected intake air amount Deviation occurs between the two, and the control accuracy decreases.

One of the purposes of this case was created in view of the above-mentioned problems, and can evaluate the intake performance of an engine that is not influenced by pressure changes in the intake system and improve the output torque control stability. It is to provide a control device.
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) The engine control device disclosed herein is based on an output request to the engine with respect to a maximum torque equivalent value generated in the engine at a maximum air amount introduced into the engine in accordance with the rotational speed of the engine. Pressure ratio equivalent value calculating means for calculating the ratio of the target torque equivalent value of the engine set as a pressure ratio equivalent value. Further, the apparatus includes 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 with the intake system pressure based on the pressure ratio equivalent value and the rotation speed of the engine. Furthermore, a torque control means for controlling the output torque of the engine based on the volumetric efficiency coefficient is provided.

(2) An intake pressure sensor provided in the intake system of the engine for detecting the intake system pressure, and a downstream of the upstream pressure of the throttle valve portion of the intake system based on the intake system pressure detected by the intake pressure sensor. It is preferable to include pressure ratio calculation means for calculating the pressure ratio as an actual pressure ratio. Further, an actual volume efficiency coefficient calculating means for calculating an actual volume efficiency coefficient that is an actual measurement value of a value obtained by standardizing the volume efficiency of the engine with the intake system pressure based on the actual pressure ratio and the rotation speed of the engine. Is preferred.
In this case, it is preferable that the torque control means controls the output torque of the engine based on the volumetric efficiency coefficient and the actual volumetric efficiency coefficient.

(3) The torque control means controls the output torque of the engine based on the volumetric efficiency coefficient when the intake pressure sensor fails, and sets the actual volumetric efficiency coefficient when the intake pressure sensor does not fail. Based on this, it is preferable to control the output torque of the engine.
(4) Moreover, it is preferable that the said pressure ratio equivalent value calculating means calculates the said maximum torque equivalent value according to the valve lift amount or valve timing of an intake / exhaust valve.
That is, it is preferable to calculate the maximum engine torque that can be generated in the control state of the intake and exhaust valves at the time of calculation as the maximum torque equivalent value.

Incidentally, the maximum amount of air and is preferably the amount of air introduced into the engine when the time of the throttle opening actual rotational speed of the engine is assumed to be fully open it. In other words, the maximum torque equivalent value is preferably a torque generated in the engine when it is assumed that the throttle opening is fully open at the actual rotation speed at that time.

( 5 ) Further, it is preferable that the pressure ratio equivalent value calculating means calculates a torque generated in the engine when the ignition timing is an optimum ignition timing (that is, MBT) as the maximum torque equivalent value. When the ignition timing cannot be set to the optimum ignition timing from the viewpoint of preventing knocking, the torque generated when ignition is performed at a predetermined ignition timing slightly retarded from the optimum ignition timing is the maximum torque. You may calculate as an equivalent value.

( 6 ) Further, it is preferable that the pressure ratio equivalent value calculating means calculates a maximum torque generated in the engine at the time of combustion at a predetermined air-fuel ratio set in advance as the maximum torque equivalent value. Specific examples of the predetermined air-fuel ratio include a stoichiometric air-fuel ratio (for example, an air-fuel ratio of around 14.7) and an output air-fuel ratio (for example, an air-fuel ratio of 12.0 to 13.0).
( 7 ) Further, the pressure ratio equivalent value calculating means calculates the maximum charging efficiency of the engine as the maximum torque equivalent value and calculates the target torque equivalent value based on the amount of air introduced into the engine. It is preferable to calculate the pressure ratio equivalent value using the target filling efficiency.

In the disclosed engine control device, a value obtained by standardizing the volumetric efficiency with the intake system pressure is used, so that it is possible to grasp the ease of intake without depending on the pressure change of the intake system. By calculating such a “standardized value” based on the pressure ratio equivalent value, it is possible to grasp “the ease of intake that does not depend on the pressure change of the intake system” without actually measuring the intake system pressure. The output torque when the volumetric efficiency of the engine fluctuates can be accurately calculated.
Therefore, the controllability of the engine torque can be improved. In addition, a variety of maps and tables corresponding to the engine operating conditions are not required, and the ROM capacity for storing data related to computation can be reduced.

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. 4 is a graph illustrating the relationship between an actual rotational speed Ne and a pressure ratio C (or pressure ratio equivalent value A) and an actual volume efficiency coefficient K _mapr (or volume efficiency coefficient K _map ) according to the present control device. It is a graph which illustrates the index value of the intake performance computed with this control device, (a) is a graph which shows relation between intake manifold pressure _PIM and volumetric efficiency Ev, (b) is intake manifold pressure _PIM and actual volumetric efficiency. It is a graph which shows the relationship with the coefficient K _mapr . It is a graph which illustrates the relationship between the actual charging efficiency Ec, ignition timing, and torque which concerns on this control apparatus. It is a graph illustrating the relationship between the maximum torque Pi _MAX of this controller (or maximum charging efficiency Ec _MAX) and the actual actual rotational speed Ne. It is a graph for demonstrating the correlation with the pressure ratio equivalent value which concerns on this control apparatus, and the actual pressure ratio C, (a) is what used the pressure ratio equivalent value A calculated based on the indicated mean effective pressure (B) uses the pressure ratio equivalent value B calculated based on the charging efficiency.

  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. engine]
The engine control device of the present embodiment is applied to the in-vehicle gasoline engine 10 shown in FIG. Here, one of a plurality of cylinders provided in the multi-cylinder engine 10 is shown. 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. 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.

  The variable valve mechanism 27 changes the valve lift amount and the valve timing individually or in conjunction with each of the intake valve 14 and the exhaust valve 15. The variable valve mechanism 27 includes a VVL device 27a and a VVT device 27b as a mechanism for changing the rocking amount and rocking timing of the rocker arm.

The VVL device 27a is a mechanism that continuously changes the valve lift amounts of the intake valve 14 and the exhaust valve 15. The VVL device 27a has a function of changing the magnitude of the swing transmitted from the cam fixed to the camshaft to the rocker arm. A specific structure for changing the magnitude of the rocker arm swing is arbitrary.
The VVT device 27b is a mechanism that changes the opening / closing timing (valve timing) of the intake valve 14 and the exhaust valve 15. The VVT device 27b has a function of changing the rotational phase of the cam or camshaft that causes the rocker arm to swing. By changing the rotational phase of the cam or the camshaft, the rocker arm swing timing with respect to the rotational phase of the crankshaft 17 can be continuously changed (shifted).

[1-2. 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.

[1-3. 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 . The atmospheric pressure B _P 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 (detection means) 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 an intake manifold pressure P _IM (an intake manifold pressure corresponding to the pressure in the surge tank 21) is provided on the downstream side 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.

Incidentally, intake manifold pressure P _IM detected by the atmospheric pressure B _P and intake manifold pressure sensor 34 detected by the atmospheric pressure sensor 32, the engine control apparatus 1 is used for calculation of the evaluation index values of the intake performance of the engine. On the other hand, in the engine control device 1, the atmospheric pressure B _P , so that the intake performance of the engine 10 can be evaluated even when the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 fail (including when the function is deteriorated or when a failure occurs). a metric that is independent of the intake manifold pressure P _IM, calculation of volumetric efficiency factor is the evaluation index of the intake performance equivalent to the volume efficiency is implemented. In the present embodiment, the function will be described by paying attention to the volume efficiency coefficient calculation method.

[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 device 1 calculates a volumetric efficiency coefficient K _map and an actual volumetric efficiency coefficient K _mapr as index values for evaluating the intake performance of the engine 10, and is introduced into (or introduced into) the cylinder 19 based on these. ) Estimate the actual air volume and control the output torque. The actual air amount calculated based on the volumetric efficiency coefficient K _map and the actual volumetric efficiency coefficient K _mapr (for example, the actual intake air amount, the actual charging efficiency, etc.) is the amount of fuel injected from the injector 18 and the spark plug 13. Used for ignition timing control.

  The engine control apparatus 1 includes a first calculation unit 2, a second calculation unit 3, and a torque 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. First calculation unit]
The first calculation unit 2 calculates an actual volume efficiency coefficient K _mapr that is one of index values for evaluating the intake performance of the engine 10. The actual volume efficiency coefficient K _mapr is obtained by standardizing the volume efficiency Ev with respect to the intake system pressure. In this embodiment, as shown in the following formula 1, the volumetric efficiency Ev is converted to a value when the atmospheric pressure at the time of measurement is the standard atmospheric pressure (one atmospheric pressure; 101.3 [kPa]), and the actual volume The efficiency coefficient is defined as K _mapr .

The first calculation unit 2 calculates the actual volumetric efficiency factor K _MAPR based on intake manifold pressure P _IM detected by the intake manifold pressure sensor 34. Incidentally, based on the definition of formula 1, can be determined volumetric efficiency Ev from the intake manifold pressure P _IM and actual volumetric efficiency factor K _MAPR.

As shown in FIG. 1, the first calculation unit 2 is provided with a pressure ratio calculation unit 2A and an actual volume efficiency coefficient calculation unit 2B. 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 C based on the sensor detection value related to the intake system pressure. Pressure ratio C of this embodiment is given by Equation 2 below using the atmospheric pressure B _P detected by the intake manifold pressure P _IM and the atmospheric pressure sensor 32 detected by the intake manifold pressure sensor 34.
The value of the pressure ratio C calculated here is transmitted to the actual volume efficiency coefficient calculation unit 2B. Note that a value obtained by subtracting the amount of pressure loss in the intake passage 24 from the atmospheric pressure B _P may be obtained as the upstream pressure of the throttle valve 23, and this may be used as the denominator of Equation 2.

The actual volume efficiency coefficient calculation unit 2B (actual volume efficiency coefficient calculation means) calculates an actual volume efficiency coefficient K _mapr based on the actual rotation speed Ne of the engine 10 and the pressure ratio C. Here, correspondence maps, mathematical expressions, and relational expressions of the actual rotational speed Ne and the pressure ratio C and the actual volume efficiency coefficient K _mapr are set in advance, and the actual volume efficiency coefficient calculation unit 2B is based on such a relationship. _{Calculate the} actual volumetric efficiency coefficient K _mapr . The value of the actual volume efficiency coefficient K _mapr calculated here is transmitted to the torque control unit 4.
As a map for _{obtaining the} actual volume efficiency coefficient K _mapr , for example, a map as shown in FIG. 2 is used. This map corresponds to a representation of the right side (volumetric efficiency Ev and intake manifold pressure P _IM ) of Equation 1 above as a function of the actual rotational speed Ne and the pressure ratio C.

Here, the relationship between the general volume efficiency Ev and the actual volume efficiency coefficient K _mapr will be supplementarily described. Volumetric efficiency Ev of the engine 10, as shown in FIG. 3 (a), a smaller value as the intake manifold pressure P _IM decreases. On the other hand, the relationship between these values is not necessarily linear, the change amount (change gradient) volumetric efficiency Ev when changing the intake manifold pressure P _IM increases as decreases 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. Therefore, when evaluating the intake performance of the engine 10 in the operation state where the intake manifold pressure _PIM is low, it is desirable to separately evaluate these two kinds of influences.

On the other hand, actual volumetric efficiency factor K _MAPR from its definition, is a parameter with a real number times the size of a value obtained by dividing the volumetric efficiency Ev in the intake manifold pressure P _IM. That is, as shown in the graph of FIG. 3 (b), the value of the actual volumetric efficiency factor K _MAPR changes to converge to a predetermined value D as intake manifold pressure P _IM increases. Further, the magnitude of the difference between the predetermined value D and the actual volumetric efficiency coefficient K _mapr is a value that reflects only the influence of the ease of entering the intake air determined according to the operating state of the variable valve mechanism 27 and the like. In this manner, by using the actual volumetric efficiency factor K _MAPR instead of 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.

However, since the actual volume efficiency coefficient K _mapr calculated by the actual volume efficiency coefficient calculation unit 2B is calculated from the sensor detection value related to the intake system pressure, the calculation accuracy depends on the detection accuracy of the sensor. For example, if the atmospheric pressure sensor 32 or the intake manifold pressure sensor 34 fails, the actual volume efficiency coefficient K _mapr may not be correctly calculated. Therefore, in the present embodiment, the second calculation unit 3 is provided for calculating a parameter corresponding to the actual volume efficiency coefficient K _mapr without using a sensor related to the intake system pressure.

[2-2. Second calculation unit]
The second calculation unit 3 calculates a pressure ratio equivalent value A that correlates with the pressure ratio C calculated by the pressure ratio calculation unit 2A. As shown in FIG. 1, the second calculator 3 includes a maximum torque calculator 3A, a target torque calculator 3B, a pressure ratio equivalent value calculator 3C, a first corrector 3D, a second corrector 3E, and a volumetric efficiency coefficient. A calculation unit 3F is provided.

The maximum torque calculator 3A calculates the maximum torque Pi _MAX that can be generated in the engine 10 based on the actual rotational speed Ne of the engine 10. In general, the magnitude of torque generated in the engine 10 varies according to the engine speed, the amount of air introduced into the cylinder, the amount of fuel, the ignition timing, and the like. The magnitude of torque generated at a predetermined air-fuel ratio when the engine speed is a predetermined value (constant) is represented by a graph as shown in FIG. When the air amount is Q ₁ , the engine 10 outputs the maximum torque Pi ₁ when the ignition timing is T ₁ . When the fluctuation of the torque with respect to the ignition timing is indicated by a curve, the curve is convex upward. The maximum torque when the air amount is Q ₂ is Pi ₂ , and the ignition timing for outputting the torque is T ₂ .

Based on these relationships, the maximum torque calculation unit 3A maximizes the maximum value of torque (torque when the throttle is fully open) generated when the intake air amount is maximum in the operating state of the engine 10 at that time. Calculated as torque Pi _MAX . For example, as shown by a solid line in FIG. 5, the maximum torque Pi _MAX is calculated using a graph, a correspondence map, an equation, etc. that define the correspondence between the maximum torque Pi _MAX and the actual rotational speed Ne when the throttle is fully opened. May be. The value of the maximum torque Pi _MAX calculated here is transmitted to the pressure ratio equivalent value calculation unit 3C and the second correction unit 3E.

Like ignition timings T ₁ and T ₂ shown in FIG. 4, an ignition timing at which the engine 10 generates the maximum torque is called an optimal ignition timing (MBT: Minimum spark advance for Best Torque). The optimum ignition timing moves toward the retard side (retard side) as the amount of air introduced into the cylinder 19 increases, and moves toward the advance side (advance side) as the amount of air decreases. Further, the optimum ignition timing moves to the retard side as the actual rotational speed Ne decreases, and moves to the advance side as the actual rotational speed Ne increases.

In the calculation of the maximum torque Pi _{MAX in} the maximum torque calculation unit 3A, basically, the torque generated when ignition is performed at the optimal ignition timing is calculated as the maximum torque Pi _MAX . However, when the ignition timing cannot be set to the optimal ignition timing from the viewpoint of preventing knocking of the engine 10, the torque generated when the ignition is ignited at a predetermined ignition timing slightly behind the optimal ignition timing is set to the maximum torque Pi. Calculate as _MAX . Knocking is less likely to occur as the ignition timing is delayed, but engine torque decreases as the ignition timing is delayed. Therefore, it is preferable to set the predetermined ignition timing close to the advance angle close to the optimal ignition timing in the ignition timing range where almost no knock occurs.

When the ignition timing is changed, the correspondence relationship between the maximum torque Pi _MAX and the actual rotational speed Ne when the throttle is fully opened also changes, and the position and shape of the solid line graph in FIG. 5 change. On the other hand, as shown by a broken line in FIG. 5, by setting a graph corresponding to a plurality of ignition timings in advance, the maximum torque Pi _MAX corresponding to the ignition timing can be calculated. Therefore, the maximum torque calculator 3A may calculate the maximum torque Pi _MAX according to the actual rotational speed Ne and the ignition timing.

Regarding the air-fuel ratio, it is preferable to calculate the maximum torque Pi _MAX on the assumption that the air-fuel ratio is not the actual air-fuel ratio at that time but a predetermined air-fuel ratio set in advance. For example, even if the actual air-fuel ratio is a lean air-fuel ratio, the estimated value of the engine output at the stoichiometric air-fuel ratio (an air-fuel ratio of around 14.7) or the output air-fuel ratio (the air-fuel ratio of 12.0 to 13.0 that provides a high output) Can be calculated as the maximum torque Pi _MAX .

Similar to the ignition timing, if the air-fuel ratio which is a precondition for calculating the maximum torque Pi _MAX is different, the value of the calculated maximum torque Pi _MAX is also different. On the other hand, as shown by broken lines in FIG. 5, the maximum torque Pi _MAX corresponding to the air-fuel ratio can be calculated by setting a graph corresponding to a plurality of air-fuel ratios in advance. Therefore, the maximum torque calculator 3A may calculate the maximum torque Pi _MAX according to the actual rotational speed Ne and the air-fuel ratio.

Further, the same applies to the valve lift amount and valve timing of the intake valve 14 and the exhaust valve 15, and the optimum valve timing and the optimum valve lift amount (that is, the valve lift amount and the valve timing that cause the engine to generate the largest torque). it may be calculated the maximum torque Pi _MAX when it, or the valve lift at that time, may be calculated maximum torque Pi _MAX generated by the engine 10 in the valve timing.

Also in this case, as shown by a broken line in FIG. 5, a graph corresponding to a plurality of valve lift amounts and valve timings is set in advance to calculate the maximum torque Pi _MAX corresponding to the valve lift amount and valve timing. Is possible. Therefore, the maximum torque calculator 3A may calculate the maximum torque Pi _MAX according to the actual rotational speed Ne, the valve lift amount, and the valve timing.

Target torque calculation unit 3B, based on the actual rotational speed Ne and the accelerator opening A _PS, it is intended for calculating a target torque Pi _TGT. This target torque Pi _TGT is a torque required for the engine 10, and is a value obtained by converting a target value of the output torque of the engine 10 in the torque base control into the indicated mean effective pressure. Here, correspondence maps, mathematical expressions, and relational expressions of the actual rotational speed Ne, the accelerator opening degree A _PS, and the target torque Pi _TGT are set in advance, and the target torque calculation unit 3B sets the target torque based on such a relationship. Calculate Pi _TGT . The value of the target torque Pi _TGT calculated here is transmitted to the pressure ratio equivalent value calculation unit 3C.

The pressure ratio equivalent value calculation unit 3C (pressure ratio equivalent value calculation means) is based on the maximum torque Pi _MAX calculated by the maximum torque calculation unit 3A and the target torque Pi _TGT calculated by the target torque calculation unit 3B. The equivalent value A is calculated. The pressure ratio equivalent value A is given as a ratio of the target torque Pi _TGT to the maximum torque Pi _{MAX as} shown in the following expression 3. The pressure ratio equivalent value A calculated here is transmitted to the volumetric efficiency coefficient calculation unit 3F.

  The relationship between the pressure ratio equivalent value A and the actual pressure ratio C of the throttle valve 23 is graphed and shown in FIG. This graph plots the relationship between the pressure ratio equivalent value A and the pressure ratio C when the actual rotational speed Ne and the air-fuel ratio are constant and the valve lift amount of the intake valve 14 is changed. The horizontal and vertical axes of the graph are the pressure ratio equivalent value A and the pressure ratio C, respectively, and the white circles arranged in dotted lines are the points where the pressure ratio equivalent value A and the pressure ratio C are the same value (C = A Points on a straight line graph).

In this graph, the results when the valve lift amount of the intake valve 14 is sequentially increased in four stages of L ₁ , L ₂ , L ₃ , and L ₄ are expressed by a thin broken line, a thin solid line, a thick broken line, and a thick solid line. Yes. Each of the four graphs has a shape substantially along a dotted white circle. That is, a correlation independent of the valve lift amount is recognized between the pressure ratio equivalent value A and the pressure ratio C, and the pressure ratio equivalent value A can be used as an alternative parameter for the pressure ratio C.

  The use of the pressure ratio equivalent value A as a substitute value for the pressure ratio C is synonymous with the assumption that the pressure ratio C and the pressure ratio equivalent value A are always equal. On the other hand, the graph in FIG. 6A does not exactly match the C = A line graph. Therefore, the value used for the calculation of the pressure ratio equivalent value A may be corrected so that the correlation between the pressure ratio equivalent value A and the pressure ratio C is further strengthened. Alternatively, the pressure ratio equivalent value A ′ corrected for the deviation from the pressure ratio C may be calculated to improve the reliability as a substitute value for the pressure ratio C.

The first correction unit 3D performs the former correction calculation. For example, the first correction unit 3D stores the influence of the air-fuel ratio, valve timing, valve lift amount, etc. on the maximum torque Pi _MAX , and the operating state of the engine 10 and the control states of the intake valve 14 and the exhaust valve 15 at that time. Accordingly, the corrected maximum torque Pi _MAX ′ is calculated and transmitted to the maximum torque calculator 3A. In this case, the maximum torque calculator 3A is configured to transmit the corrected maximum torque Pi _MAX ′ transmitted from the first corrector 6D to the pressure ratio equivalent value calculator 3C as the maximum torque Pi _MAX .

  The second correction unit 3E performs the latter correction calculation. For example, the second correction unit 3E stores the correspondence relationship between the pressure ratio C and the pressure ratio equivalent value A as shown in FIG. 6A for each actual rotational speed Ne, each valve timing, and each valve lift amount. The pressure ratio A ′ corresponding to the pressure ratio equivalent value A calculated by the ratio equivalent value calculation unit 3C is calculated, and this is transmitted again to the pressure ratio equivalent value calculation unit 3C. In this case, the pressure ratio equivalent value calculator 3C overwrites and updates the pressure ratio equivalent value A calculated by the pressure ratio equivalent value calculator 3C with the pressure ratio A ′ transmitted from the second corrector 3E. A ratio equivalent value A is transmitted to the second calculation unit 7.

The volumetric efficiency coefficient computing unit 3F (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 equivalent value A. Here, the calculation using the pressure ratio equivalent value A instead of the pressure ratio C is performed among the calculations in the actual volume efficiency coefficient calculation unit 2B. For example, the volumetric efficiency coefficient K _map is calculated using a correspondence map as shown in FIG. The volume efficiency coefficient K _map calculated here is transmitted to the torque control unit 4.

[2-3. Torque control unit]
The torque control unit 4 (torque control means) outputs the output torque of the engine 10 based on the actual volume efficiency coefficient K _mapr calculated by the first calculation unit 2 and the volume efficiency coefficient K _map calculated by the second calculation unit 3. Is to control. Here, the volumetric efficiency coefficient K _map is used when at least one of the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 fails, and the actual volumetric efficiency coefficient K _mapr is used when neither sensor 32 or 34 fails. It is done.

The torque control unit 4 of the present embodiment repeatedly calculates the actual volume efficiency coefficient K _mapr and the volume efficiency coefficient K _map at a predetermined period, and calculates the actual charging efficiency Ec corresponding to the amount of air actually sucked into the cylinder 19. Use these. Hereinafter, both the actual volume efficiency coefficient K _mapr and the volume efficiency coefficient K _map obtained in this calculation cycle are denoted as volume efficiency coefficient K _{map (n),} and the value in the previous calculation cycle is represented by K _{map (n -1)} . Here, the value of the actual charging efficiency Ec is calculated based on the intake flow rate Q and the volumetric efficiency coefficients _{Kmap (n)} and _{Kmap (n-1)} .

First, the torque control unit 4 calculates a detected filling efficiency Ec _(r) corresponding to the actual filling efficiency Ec at the position where the air flow sensor 35 is provided, based on the intake flow rate Q. The detected charging efficiency Ec _(r) is a parameter corresponding to the amount of air newly introduced into the cylinder 19 in one intake stroke. Note that the value of the actual filling efficiency Ec varies slightly later than 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.

The torque control unit 4 calculates the actual charging efficiency Ec based on the following equations 4 and 5. In Equation 4, Ec _(n) is a value in the current calculation cycle, and Ec _(n-1) is a value in the previous calculation cycle. X is a time constant for giving a change corresponding to the intake response delay to the value of the actual charging efficiency Ec, Vs is the volume of the surge tank 21, and Vc is the volume of the cylinder 19.

In the above calculation, the current value for the volumetric efficiency coefficient K _{map (n-1)} in the previous calculation cycle is used as one of the coefficients multiplied by the actual filling efficiency Ec _(n-1) obtained in the previous calculation cycle. The ratio of K _{map (n)} is used. The value of this ratio (K _{map (n)} / K _{map (n-1)} ) is always 1 when the volumetric efficiency of the engine 10 does not change, and this affects the actual calculation of the actual charging efficiency Ec _(n). Don't give. On the other hand, when the detected charging efficiency Ec _(r) 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 increases. The ratio value decreases as efficiency 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.

[3. Action, effect]
The volumetric efficiency Ev of the engine 10 is not only influenced by the pressure of the intake system, but also by the intake resistance determined according to the valve lift amount and valve timing of the intake and exhaust valves 14 and 15, and further, the burned gas Fluctuates under the influence of residual amount. Therefore, when the calculated value of the volumetric efficiency Ev changes, it is not easy to identify whether the change is due to a change in pressure in the intake system or due to other factors.

(1) On the other hand, in the engine control apparatus 1 described above, since the value obtained by standardizing the volumetric efficiency Ev with the intake system pressure is used, it is possible to grasp the ease of intake without depending on the pressure change of the intake system.
That is, in the engine control device 1, the pressure ratio equivalent value calculation unit 3C of the second calculation unit 3 calculates the pressure ratio equivalent value A instead of the actual pressure ratio C of the throttle valve 23 unit. Further, the volumetric efficiency coefficient calculation unit 3F calculates the volumetric efficiency coefficient K _map based on the actual rotational speed Ne and the pressure ratio equivalent value A. Further, the torque control unit 4 calculates the actual charging efficiency Ec based on the volumetric efficiency coefficient K _map when the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 fail.

In this way, by calculating the actual charging efficiency Ec using the "normalized values" volumetric efficiency Ev in the intake system pressure, to grasp the enter ease of intake air without depending on the change of the intake manifold pressure P _IM It is possible to improve the calculation accuracy of the actual filling efficiency Ec. 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.
Further, as shown in FIG. 6 (a), since the pressure ratio equivalent value A is correlated with the pressure ratio C of the throttle valve 23, the actual charging efficiency Ec can be calculated with high accuracy, and an appropriate value can be obtained. The fuel injection amount and ignition timing can be set. Furthermore, by utilizing the correlation between the pressure ratio equivalent value A and the pressure ratio C, a complicated map or table corresponding to various operating states of the engine 10 is not required, and the ROM capacity for storing data relating to torque base control Can be reduced.

  (2) In addition, by calculating the “standardized value” as described above based on the pressure ratio equivalent value A, it is possible to calculate “the ease of entering the intake air regardless of the intake system pressure change without actually measuring the intake system pressure. And the output torque when the volumetric efficiency of the engine 10 fluctuates can be accurately calculated. For example, even when the detection accuracy of the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 is deteriorated or a failure occurs, an accurate value of the actual filling efficiency Ec can be calculated. Therefore, calculation of the fuel injection amount and torque setting accuracy in torque-based control can be improved, and engine torque controllability can be improved.

In addition, since the parameter used for the calculation of the actual filling efficiency Ec is switched to either the volume efficiency coefficient K _{map or the} actual volume efficiency coefficient K _mapr according to the failure state of the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34, The output torque of the engine 10 does not change significantly before and after the occurrence of a failure. That is, torque control that is the same as that at non-failure can be continued even during failure. Thereby, for example, it is possible to ensure the calculation accuracy of the torque during traveling until the failed sensor is replaced.

(3) Further, in the engine control apparatus 1 described above, the first calculation unit 2 calculates the actually measured pressure ratio C of the throttle valve 23 unit, and the actual volume efficiency based on the pressure ratio C and the actual rotational speed Ne. The coefficient K _mapr is calculated. In the torque control unit 4, the actual filling efficiency Ec is calculated based on the actual volume efficiency coefficient K _mapr when the atmospheric pressure sensor 32 and the intake manifold pressure sensor 34 are not failed.
Thereby, when the detection accuracy of each sensor 32 and 34 is ensured, the value of the appropriate actual filling efficiency Ec based on an actual measurement value is computable. Therefore, calculation of the fuel injection amount and torque setting accuracy in torque-based control can be improved, and engine torque controllability can be improved.

(4) Further, the engine control device 1 is provided with the second correction unit 3E in the second calculation unit 3, and the calculated value of the maximum torque Pi _MAX is determined according to the air-fuel ratio, the valve lift amount, and the valve timing. It is corrected. Thereby, the intake performance of the engine 10 can be evaluated regardless of the combustion mode such as the lean operation and the stoichiometric operation and the control state of the intake valve 14 and the exhaust valve 15.

(5) Regarding the calculation method of the pressure ratio equivalent value A, the engine control apparatus 1 calculates the pressure ratio equivalent value A using the maximum torque Pi _MAX and the target torque Pi _TGT at that time. These maximum torque Pi _MAX and target torque Pi _TGT are parameters that can be used in torque base control other than fuel injection amount control and ignition timing control, such as EGR control and intake air amount control, for example. There is an advantage that reuse for other control is easy, and simplification of the control program and algorithm is easy.

(6) Further, regarding the calculation of the maximum torque Pi _MAX , the maximum torque calculation unit 6a calculates the torque generated in the engine 10 as the maximum torque Pi _MAX when the ignition timing is set to the optimal ignition timing. That is, even if the actual ignition timing is not the optimal ignition timing, the maximum torque that can be generated by the engine 10 at that time is calculated as the maximum torque Pi _MAX . Thereby, the correlation between the pressure ratio equivalent value A and the actual pressure ratio C can be enhanced.

(7) Furthermore, when the maximum torque Pi _MAX is calculated under the condition of a constant predetermined air-fuel ratio such as stoichiometric air-fuel ratio or output air-fuel ratio, the influence of the difference in torque derived from the air-fuel ratio can be removed, The correlation between the pressure ratio equivalent value A and the actual pressure ratio A can be further increased.

[4. Modified example]
[4-1. Calculation of pressure ratio equivalent value using filling efficiency]
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. In the engine control apparatus 1 described above, the pressure ratio equivalent value A is calculated using the maximum torque Pi _MAX and the target torque Pi _TGT of the engine 10, but the amount of air introduced into the cylinder 19 instead of the torque. It is also possible to perform the same calculation by using.

For example, instead of the maximum torque Pi _MAX and the target torque Pi _TGT of the above-described embodiment, the second pressure ratio equivalent value B is calculated using the maximum charging efficiency Ec _MAX and the target charging efficiency Ec _TGT, and the second pressure ratio It can be considered that the volumetric efficiency coefficient K _map is calculated based on the equivalent value B. The maximum charging efficiency Ec _MAX is the charging efficiency Ec corresponding to the maximum torque Pi _MAX in the above-described embodiment, and is calculated based on the amount of air required to generate the maximum torque Pi _MAX in the engine 10. Efficiency Ec (charging efficiency Ec when the throttle opening is fully opened). The target charging efficiency Ec _TGT is charging efficiency Ec corresponding to the target torque Pi _TGT, a charging efficiency Ec calculated based on the amount of air required to generate the target torque Pi _TGT engine 10. Using these parameters, the ratio of the target filling efficiency Ec _TGT to the maximum filling efficiency Ec _MAX can be set to the second pressure ratio equivalent value B (B = Ec _TGT / Ec _MAX ) as shown in the following Equation 6. it can.

  Here, FIG. 6B illustrates the relationship between the second pressure ratio equivalent value B confirmed through the tests by the present inventors and the actual pressure ratio C of the throttle valve 23 part. Similar to FIG. 6A, this graph shows the respective second pressure ratio equivalent values B when the actual rotational speed Ne and the air-fuel ratio of the engine 10 are constant and the valve lift amount of the intake valve 14 is changed. The relationship with the pressure ratio C is plotted.

Each of the four graphs with different valve lifts has a shape along a dotted white circle, and a correlation independent of the valve lift amount is recognized between the second pressure ratio equivalent value B and the pressure ratio C. . Therefore, the throttle opening degree θ _TH can be calculated using the second pressure ratio equivalent value B instead of the pressure ratio C.

[4-2. Others]
In the above embodiment, the method for obtaining the actual filling efficiency Ec based on the volumetric efficiency coefficient K _map has been exemplified, but the calculation for using the volumetric efficiency coefficient is not limited to this. For example, it is conceivable to calculate the actual charging efficiency Ec without using the value of the intake flow rate Q by using the volumetric efficiency coefficient K _map and information on the temperature and density of the intake air. In this case, the airflow sensor 35 can be omitted, and the device configuration can be simplified. Therefore, it can be applied to both the mass flow method and the speed density method in the fuel injection amount control.

Further, in the above-described embodiment, the example in which the pressure ratio equivalent value A is calculated using the maximum torque Pi _MAX and the target torque Pi _TGT expressed by the indicated mean effective pressure Pi is illustrated, but a specific pressure ratio equivalent value is illustrated. The calculation method of A is not limited to this. For example, the pressure ratio equivalent value A may be calculated using the net average effective pressure Pe or the torque value generated in the crankshaft 17 instead of the indicated average effective pressure Pi. Further, the second pressure ratio equivalent value B may be calculated using the air amount (air volume or mass) instead of the charging efficiency Ec in the above-described modification.

  Moreover, although the above-mentioned embodiment illustrated what presupposes what is called torque base control on the basis of the magnitude | size of the torque requested | required of the engine 10, torque base control is not an essential element. As long as it is an engine control device that functions as torque control means for controlling the output torque of the engine 10, at least the same control as in the above-described embodiment can be performed. The control of the above-described embodiment can be applied not only to a gasoline engine but also to a diesel engine.

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 1st calculating part 2A Pressure ratio calculating part (pressure ratio calculating means)
2B Actual volume efficiency coefficient calculation unit (actual volume efficiency coefficient calculation means)
3 Second calculation unit 3A Maximum torque calculation unit 3B Target torque calculation unit 3C Pressure ratio equivalent value calculation unit (pressure ratio equivalent value calculation means)
3F volumetric efficiency coefficient calculation unit (volumetric efficiency coefficient calculation means)
4 Torque control unit (torque control means)

Claims (7)

The ratio of the target torque equivalent value of the engine set based on the output request to the engine with respect to the maximum torque equivalent value generated in the engine at the maximum amount of air introduced into the engine according to the rotational speed of the engine Pressure ratio equivalent value calculating means for calculating the pressure ratio equivalent value;
Volumetric efficiency coefficient calculating means for calculating a volumetric efficiency coefficient corresponding to a value obtained by standardizing the volumetric efficiency of the engine with the intake system pressure based on the pressure ratio equivalent value and the rotational speed of the engine;
An engine control apparatus comprising: torque control means for controlling output torque of the engine based on the volumetric efficiency coefficient. An intake pressure sensor provided in the intake system of the engine for detecting the intake system pressure;
Pressure ratio calculation means for calculating a ratio of the downstream pressure to the upstream pressure of the throttle valve portion of the intake system as an actual pressure ratio based on the intake system pressure detected by the intake pressure sensor;
An actual volume efficiency coefficient calculating means for calculating an actual volume efficiency coefficient that is an actual measurement value of a value obtained by standardizing the volume efficiency of the engine with the intake system pressure based on the actual pressure ratio and the rotational speed of the engine;
The engine control apparatus according to claim 1, wherein the torque control means controls the output torque of the engine based on the volumetric efficiency coefficient and the actual volumetric efficiency coefficient. The torque control means is
When the intake pressure sensor fails, the engine output torque is controlled based on the volumetric efficiency coefficient,
The engine control device according to claim 2, wherein the engine output torque is controlled based on the actual volumetric efficiency coefficient when the intake pressure sensor is not failing. The engine according to any one of claims 1 to 3, wherein the pressure ratio equivalent value calculating means calculates the maximum torque equivalent value in accordance with a valve lift amount or valve timing of an intake / exhaust valve. Control device. The pressure ratio equivalent value calculating means, the torque generated by the engine when the optimal ignition timing and the ignition timing, characterized in that calculated as the maximum torque value corresponding to any one of claims 1-4 the engine control apparatus according to. The pressure ratio equivalent value calculating means, characterized by calculating the maximum torque generated by the engine during combustion at a predetermined air-fuel ratio set in advance as the maximum torque equivalent value, one of claims 1 to 5 or control device for an engine according to (1). The pressure ratio equivalent value calculating means uses the maximum charging efficiency of the engine as the maximum torque equivalent value, and uses the target charging efficiency calculated based on the amount of air introduced into the engine as the target torque equivalent value. Te, characterized by calculating the pressure ratio equivalent value, the engine control apparatus according to any one of claims 1-6.

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