JP2012172616A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the calculation accuracy of a target opening of a throttle valve corresponding to required engine torque, in a control device for an engine.SOLUTION: A first calculation means 1 for calculating a ratio of a target torque equalizing value to a maximum torque equalizing value of the engine 10 as a pressure ratio equalizing value is provided. A second calculation means 2 for calculating a ratio of a downstream pressure equalizing value to an upstream pressure equalizing value of a throttle valve 24 as the practical pressure ratio is provided. Further, a third calculation means 3 for calculating the target opening of the throttle valve 24 which is set according to the pressure ratio equalizing value is provided.

Description

  The present invention relates to an engine control device related to throttle valve opening control.

  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 the torque-based control, for example, a target value of engine torque is calculated based on the accelerator opening, the engine speed, and the like, and the engine is controlled so as to obtain this target value of torque. 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 and integrated in the engine control unit (engine ECU). The torque behavior of the engine is comprehensively controlled.

  By the way, when the combustion conditions such as the fuel injection amount and the ignition timing are constant, the magnitude of the torque generated in the engine corresponds to the intake air amount introduced into the cylinder. This intake air amount changes according to the opening degree of a throttle valve provided on the intake passage of the engine. Therefore, it is possible to control the magnitude of the engine torque by adjusting the opening of the throttle valve.

For example, Patent Document 1 describes a method of converting a target torque into a target in-cylinder charged air amount and calculating a target throttle opening so that the estimated in-cylinder charged air amount follows the target in-cylinder charged air amount. ing. In this technology, the estimated in-cylinder charged air amount is calculated using a physical model that takes into account changes in the amount of air passing through the throttle valve and delays in the intake system, and the throttle opening is controlled to approach this target value. ing.
The flow rate of air passing through the throttle valve is expressed as the product of the opening area of the throttle valve and the air flow velocity. Therefore, if the flow velocity of the air passing through the throttle valve is determined, it is possible to accurately grasp the throttle opening for generating the required engine torque.

  For example, Patent Document 2 describes a technique for calculating a value (flow coefficient) that is proportional to the flow velocity of air using the ratio of the downstream pressure to the upstream pressure (pressure ratio) of the throttle valve portion. In this technology, the pressure ratio is calculated based on the output signals of the pressure sensors provided on the upstream side and the downstream side of the throttle valve, and the estimated value of the amount of air introduced into the cylinder is calculated using this pressure ratio. ing.

JP 2009-24677 A JP 2006-132498 A

Incidentally, the intake air flow passing through the throttle valve has a characteristic that the flow velocity decreases as the pressure ratio before and after the throttle valve (ratio of downstream pressure to upstream pressure) increases. That is, a relationship as shown in FIG. 3 is recognized between the flow velocity (or mass flow rate) of the intake air and the pressure ratio of the throttle valve portion. The graph in FIG. 3 shows that when the pressure ratio is 1 (when the pressure is the same before and after the throttle valve), the flow velocity becomes 0, and when the pressure ratio is less than the critical pressure ratio Z ₀ , the flow velocity is the upper limit (corresponding to the sound velocity) The speed is constant).

The rate of decrease in the flow velocity corresponds to the gradient in the decreasing direction of the graph, and the gradient increases as the pressure ratio approaches 1. That is, the flow rate of intake air decreases as the pressure ratio increases, but the rate of decrease increases as the pressure ratio increases. Therefore, even if the amount of change in pressure ratio is the same, the amount of change in flow velocity increases as the pressure ratio is closer to 1.
On the other hand, the target opening area of the throttle valve is calculated as a value obtained by dividing the flow rate of air to be passed through the throttle valve by the flow velocity. Accordingly, the closer the pressure ratio is to 1, the more easily the target opening area of the throttle valve is likely to change greatly with respect to a slight change in the pressure ratio, and the control accuracy of actual torque due to intake air is likely to be affected. In particular, in an operating state in which the throttle opening is almost fully open, there is a problem that the pressure ratio of the throttle valve portion is likely to increase and it is difficult to improve torque control accuracy.

One of the purposes of the present case was invented in view of the above-described problems, and is to improve the control accuracy of torque by intake air by appropriately setting the opening of the throttle valve.
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 includes first calculation means for calculating a ratio of the engine target torque equivalent value to the engine maximum torque equivalent value as a pressure ratio equivalent value. Further, a second calculating means is provided for calculating the ratio of the downstream pressure equivalent value to the upstream pressure equivalent value of the throttle valve as the actual pressure ratio. Furthermore, a third calculating means for correcting a target opening of the throttle valve set according to the actual pressure ratio based on the pressure ratio equivalent value is provided.

(2) Further, the third calculation means calculates an estimated flow speed calculation means for calculating an estimated flow speed of the air passing through the throttle valve based on the actual pressure ratio, and calculates the estimated flow speed based on the pressure ratio equivalent value. It is preferable that correction means for correcting and opening degree setting means for setting a target opening degree of the throttle valve based on the estimated flow velocity corrected by the correction means.
(3) Further, the correction means includes a reference flow velocity calculation means for calculating a reference flow velocity value range of air passing through the throttle valve based on the pressure ratio equivalent value, and the estimated flow velocity value falls within the reference flow velocity value range. It is preferable to have a flow rate correction means for correcting the flow rate.

(4) Further, the reference flow velocity calculation means sets a center value of the reference flow velocity value region and a width from the center value based on the pressure ratio equivalent value, and the width is increased as the pressure ratio equivalent value is larger. It is preferable to set it narrowly.
(5) Further, the third computing means is based on the actual pressure ratio corrected by the actual pressure ratio correcting means and the actual pressure ratio correcting means for correcting the actual pressure ratio based on the pressure ratio equivalent value. A second estimated flow velocity calculating means for calculating an estimated flow velocity of air passing through the throttle valve, and a second opening setting means for setting a target opening of the throttle valve based on the estimated flow velocity. Is preferred.

(6) Moreover, it is preferable that said 1st 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.

(7) Further, a torque generated by a maximum air amount introduced into the engine according to an engine speed is calculated as the maximum torque equivalent value, and a target torque set based on an output request to the engine is calculated. It is preferable to calculate as the target torque equivalent value.
That is, the amount of air introduced into the engine is preferably the amount of air introduced into the engine when it is assumed that the throttle opening is fully open at the engine speed at that time. 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 engine speed at that time.

(8) Moreover, it is preferable that said 1st calculating means calculates the torque which generate | occur | produces in the said engine when the ignition timing is made into the optimal ignition timing (namely, MBT) as said 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.
(9) Further, it is preferable that the first calculation 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).

  (10) Further, the first calculation 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 air amount as the target torque equivalent value, It is preferable to calculate the pressure ratio equivalent value.

  According to the disclosed engine control device, the target throttle opening set in accordance with the actual pressure ratio is corrected with the pressure ratio equivalent value, thereby preventing a decrease in torque accuracy due to fluctuations in the actual pressure ratio. The target opening of the throttle valve can be appropriately controlled with respect to the target torque.

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. It is a block block diagram which shows typically the structure of the engine control apparatus of FIG. It is a graph which shows the relationship between the pressure ratio of the throttle-valve part of FIG. 1, and the flow velocity of an intake flow. It is a graph which illustrates the relationship between the engine speed and maximum torque which concern on this control apparatus with a continuous line. In addition, the broken line illustrates the change of the solid line graph when various operating conditions are changed. It is a graph which illustrates the relationship between the engine speed which concerns on this control apparatus, and a reference | standard intake pressure loss. It is a graph for demonstrating the correlation with the pressure ratio equivalent value which concerns on this control apparatus, and an actual pressure ratio, (a) uses the pressure ratio equivalent value calculated based on the illustrated mean effective pressure, b) uses the pressure ratio equivalent value calculated based on the charging efficiency. It is a graph for demonstrating the reference | standard flow velocity area in this control apparatus, (a) is a graph which illustrates the relationship between a pressure ratio equivalent value and a flow velocity, (b) is the relationship between a pressure ratio equivalent value and the width | variety of a flow velocity. FIG. It is a graph which illustrates the relationship between the intake air temperature and mass flow velocity which concern on this control apparatus. It is a graph which illustrates the relationship between the target opening area and target opening voltage of the throttle valve which concern on this control apparatus. It is a block block diagram which shows typically the structure of the control apparatus as a modification. It is a graph for demonstrating the reference | standard pressure ratio area which concerns on the control apparatus as a modification.

  The control device 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.

[1. Device configuration]
[1-1. Cylinder structure]
The engine control apparatus of this embodiment is applied to the vehicle-mounted engine 10 shown in FIG. Here, one cylinder among a plurality of cylinders provided in the multi-cylinder engine 10 is shown. The piston 16 that reciprocates in the cylinder is connected to the crankshaft 17 via a connecting rod.

The crankshaft 17, a crank angle sensor 30 is provided for detecting the rotation angle theta _CR. The amount of change in the rotation angle θ _CR per unit time is proportional to the engine speed Ne. Therefore, it can be said that the crank angle sensor 30 has a function of detecting the engine speed Ne of the engine 10. Information of the engine speed Ne detected (or calculated) here is transmitted to the engine control device 5 described later. The engine control device 5 may calculate the engine speed Ne based on the rotation angle θ _CR detected by the crank angle sensor 30.

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

  The upper ends of the intake valve 14 and the exhaust valve 15 are respectively connected to one end of a rocker shaft in the variable valve mechanism 6. The rocker shaft is a rocking member that is pivotally supported by the rocker arm, and the intake valve 14 and the exhaust valve 15 are reciprocated in the vertical direction by the rocking of each rocker shaft. A cam supported on the camshaft is provided at the other end of the rocker shaft. As a result, the rocker shaft swing pattern corresponds to the shape of the cam (cam profile).

[1-2. Valve system]
The variable valve mechanism 6 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. The variable valve mechanism 6 includes a variable valve lift mechanism 6a and a variable valve timing mechanism 6b as mechanisms for changing the rocking amount and rocking timing of the rocker shaft.

The variable valve lift mechanism 6 a is a mechanism that continuously changes the maximum valve lift amount of the intake valve 14 and the exhaust valve 15. This variable valve lift mechanism 6a 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.
For example, a structure may be considered in which a swinging member is separately interposed between a cam fixed to the camshaft and a rocker arm, and the rotational movement of the camshaft is converted into the swinging motion of the rocker arm via the swinging member. It is done. In this case, by moving the position of the swing member and changing the contact position with the cam, the swing amount of the swing member changes and the swing amount of the rocker arm also changes. As a result, the valve lift amount can be continuously changed.

Hereinafter, the angle change amount from the reference position of the swinging member with respect to the rocker shaft is referred to as a control angle θ _VVL . The control angle θ _VVL is a parameter corresponding to the valve lift amount, and the reference position of the swing member is set so that the valve lift amount increases as the control angle θ _VVL increases. The variable valve lift mechanism 6a controls the valve lift amount to an arbitrary value by adjusting the control angle θ _VVL . Information on the control angle θ _VVL controlled by the variable valve lift mechanism 6 a is transmitted to the engine control device 5.

  The variable valve timing mechanism 6 b is a mechanism that changes the opening / closing timing (valve timing) of the intake valve 14 and the exhaust valve 15. The variable valve timing mechanism 6b 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 camshaft, it is possible to continuously shift the rocker arm swinging timing with respect to the rotational phase of the crankshaft 17.

Hereinafter, a change amount of the phase angle indicating how much the actual camshaft phase angle is advanced or retarded from the reference camshaft phase angle is referred to as a phase angle _θVVT . The phase angle θ _VVT is a parameter corresponding to the valve timing. The variable valve timing mechanism 6b arbitrarily controls the valve timing by adjusting the phase angle θ _VVT . Information on the phase angle θ _VVT controlled by the variable valve timing mechanism 6 b is transmitted to the engine control device 5.

[1-3. Intake system]
An injector 18 that injects fuel is provided in the intake port 11. The amount of fuel injected from the injector 18 is electronically controlled by the engine control device 5 described later. Further, an intake manifold 20 (hereinafter referred to as an intake manifold) is provided upstream of the injector 18 in the intake air flow. The intake manifold 20 is provided with a surge tank 21 for temporarily storing air flowing toward the intake port 11 side. The intake manifold 20 on the downstream side of the surge tank 21 is formed to branch toward the intake ports 11 of the plurality of cylinders, and the surge tank 21 is located at the branch point. The surge tank 21 functions to reduce intake pulsation and intake interference generated in each cylinder.

  A throttle body 23 is connected to the upstream end of the intake manifold 20. An electronically controlled throttle valve 24 is built in the throttle body 23, and the amount of air flowing to the intake manifold 20 is adjusted according to the opening (throttle opening) of the throttle valve 24. The throttle opening is electronically controlled by an engine control device 5 described later.

An intake passage 25 is connected further upstream of the throttle body 23. An air flow sensor 27 for detecting the air flow rate Q _IN and an intake air temperature sensor 31 for detecting the intake air temperature AT are provided in the intake passage 25. Information on the flow rate Q _IN and the intake air temperature AT detected here is transmitted to the engine control device 5. An air filter 28 is interposed further upstream of the intake passage 25. Thus, fresh air filtered by the air filter 28 is supplied to the cylinder of the engine 10 via the intake passage 25 and the intake manifold 20.

At the upstream side and the downstream side of the throttle valve 24, an atmospheric pressure sensor 26 and an intake manifold pressure sensor 22 for detecting the pressure at each position are provided. The atmospheric pressure sensor 26 detects the upstream pressure P _BP (pressure corresponding to the atmospheric pressure) of the throttle valve 24, and the intake manifold pressure sensor 22 corresponds to the downstream pressure P _IM (pressure in the surge tank 21) of the throttle valve 24. Pressure). Information of the upstream pressure P _BP and downstream pressure P _IM of the throttle valve unit, which is detected by these pressure sensors 22 and 26 is transmitted to the engine control unit 5.

[1-4. Control system]
An accelerator pedal sensor 29 that detects an operation amount θ _AC corresponding to the amount of depression of the accelerator pedal is provided at an arbitrary position of the vehicle. The accelerator pedal depression operation amount θ _AC is a parameter corresponding to the driver's acceleration request, that is, corresponds to an output request to the engine 10. Information on the detected operation amount θ _AC is transmitted to the engine control device 5.

The engine control device 5 (Engine Electronic Control Unit) is an electronic control device that controls the amount of air supplied to each cylinder of the engine 10, the fuel injection amount, and the ignition timing. For example, a microprocessor, ROM, RAM, etc. It is configured as an integrated LSI device or embedded electronic device.
Here, torque base control based on the magnitude of torque required for the engine 10 is performed. Specific control objects of the engine control device 5 include the amount of fuel injected from the injector 18 and the injection timing, the ignition timing at the spark plug 13, the opening θ _TH of the throttle valve 24, and the like. In the present embodiment, its function will be described focusing on engine torque control (intake air amount control) by adjusting the throttle opening _θTH .

[2. Control configuration]
The engine control unit 5, of the torque demanded of the engine 10, the target value of the torque amount to be achieved by adjusting the intake air amount is calculated as the target torque Pi _ETV, required to generate the target torque Pi _ETV The throttle opening θ _TH is controlled so that an appropriate amount of air passes through the throttle valve 24. A variable valve mechanism 6, an intake manifold pressure sensor 22, an atmospheric pressure sensor 26, an air flow sensor 27, an accelerator pedal sensor 29, a crank angle sensor 30, and an intake air temperature sensor 31 are connected to the input side of the engine control device 5 and output side. Is connected to a throttle valve 24.

As described above, the flow rate of air passing through the throttle valve 24 is expressed as the product of the target opening area S of the throttle valve 24 and the air flow velocity V, and the air flow velocity V is the pressure ratio (upstream pressure P) of the throttle valve portion. can be calculated based on the ratio) of the downstream pressure P _IM for _BP. Therefore, if the calculated amount of air required to generate the target torque Pi _ETV is pressure between the upstream pressure P _BP detected by the downstream pressure P _IM and the atmospheric pressure sensor 26 detected by the intake manifold pressure sensor 22 The target throttle opening θ _TH can be calculated using the ratio (P _IM / P _BP ). On the other hand, the engine control apparatus 5 of the present embodiment also has a function for calculating a more appropriate target throttle opening θ _TH in consideration of the relationship between the pressure ratio and the flow velocity as shown in FIG.

  As shown in FIG. 1, the engine control device 5 includes a first calculation unit 1, a second calculation unit 2, a third calculation unit 3, and a throttle opening degree control unit 4. The functions of the first calculation unit 1, the second calculation unit 2, the third calculation unit 3 and the throttle opening control unit 4 may be realized by an electronic circuit (hardware) or programmed as software. Alternatively, a part of these functions may be provided as hardware and the other part may be software.

[2-1. First calculation unit]
The first calculation unit 1 (first calculation means) calculates the ratio of the target torque equivalent value to the maximum torque equivalent value of the engine 10 as the pressure ratio equivalent value A. The maximum torque equivalent value means the maximum torque Pi _MAX that can be generated in the engine 10 or a physical quantity corresponding to the maximum torque Pi _MAX . The maximum torque Pi _MAX is the maximum value of torque generated when the intake air amount is maximum in the operating state of the engine 10 at that time. On the other hand, the target torque equivalent value means a target torque Pi _ETV set based on an output request to the engine 10 or a physical quantity corresponding to the target torque Pi _ETV .

  Here, the pressure ratio equivalent value A is calculated separately from the pressure ratio of the throttle valve portion as a parameter corresponding to the pressure ratio. As shown in FIG. 2, the first calculation unit 1 includes a maximum torque calculation unit 1a, a target torque calculation unit 1b, a pressure ratio equivalent value calculation unit 1c, and a target flow rate calculation unit 1d.

The maximum torque calculator 1a calculates the maximum torque Pi _MAX based on the engine speed Ne detected (or calculated) by the crank angle sensor 30. The maximum torque Pi _MAX calculated here is a torque generated in the engine 10 when the throttle valve 24 is fully opened at the engine speed Ne at that time. For example, as shown by a solid line in FIG. 4, the maximum torque calculation unit 1a, using the graph or map defining the correspondence between the maximum torque Pi _MAX and the engine speed Ne at the time of full throttle, the maximum torque Pi _MAX Calculate. The maximum torque Pi _MAX calculated here is transmitted to the pressure ratio equivalent value calculation unit 1c.

In the calculation of the maximum torque Pi _{MAX in} the maximum torque calculation unit 1a, 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 between the maximum torque Pi _MAX and the engine speed Ne when the throttle is fully opened also changes, and the position and shape of the solid line graph in FIG. 4 change. On the other hand, as shown by a broken line in FIG. 4, the maximum torque Pi _MAX corresponding to the ignition timing can be calculated by setting a graph corresponding to a plurality of ignition timings in advance. Therefore, the maximum torque calculator 1a may be configured to calculate the maximum torque Pi _MAX according to the engine 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 that is the basis 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. 4, 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 calculating unit 1a may calculate the maximum torque Pi _MAX according to the engine speed Ne and the air-fuel ratio.

The same applies to the valve lift amount and valve timing of the intake valve 14 and the exhaust valve 15, and the optimal control angle θ _VVL and phase angle θ _VVT (that is, the valve lift amount and valve that cause the engine 10 to generate the largest torque). maximum torque Pi _MAX to the may be calculated, or the control angle theta _VVL at that time, may be calculated maximum torque Pi _MAX generated by the engine 10 at the phase angle theta _VVT when a timing). Also in this case, as indicated by broken lines in FIG. 4, a graph corresponding to a plurality of control angles θ _VVL and phase angles θ _VVT is set in advance, so that it corresponds to the control angles θ _VVL and phase angles θ _VVT . The maximum torque Pi _MAX can be calculated. Therefore, the maximum torque calculating unit 1a may calculate the maximum torque Pi _MAX according to the engine speed Ne, the valve lift amount, and the valve timing.

Pi of the symbol Pi _MAX which means the maximum torque means the indicated mean effective pressure (the pressure value obtained by dividing the work calculated based on the acupressure diagram of the engine 10 by the stroke volume). The magnitude of torque is expressed using the pressure Pi. In the present embodiment, not only the moment of force generated in the engine 10 but also the torque equivalent expressed by the average effective pressure (for example, the indicated average effective pressure Pi and the net average effective pressure Pe) acting on the piston 16 of the engine 10. The amount (pressure corresponding to torque) is also referred to as “torque” for convenience.

The target torque calculation unit 1b calculates the target torque Pi _ETV based on the engine speed Ne detected (or calculated) by the crank angle sensor 30 and the operation amount θ _AC detected by the accelerator pedal sensor 29. is there. The target torque Pi _ETV is a value obtained by converting the target value of the torque in the intake air amount control into the indicated mean effective pressure Pi, similarly to the maximum torque Pi _MAX . The value of the target torque Pi _ETV calculated here is transmitted to the pressure ratio equivalent value calculation unit 1c and the target flow rate calculation unit 1d.

The pressure ratio equivalent value calculation unit 1c calculates a pressure ratio equivalent value A based on the maximum torque Pi _MAX calculated by the maximum torque calculation unit 1a and the target torque Pi _ETV calculated by the target torque calculation unit 1b. is there. The pressure ratio equivalent value A is given as a ratio of the target torque Pi _ETV to the maximum torque Pi _MAX (A = Pi _ETV / Pi _MAX ). The pressure ratio equivalent value A calculated here is transmitted to the third calculation unit 3.

The target flow rate calculation unit 1d calculates a fresh air target flow rate Q _{TH_TGT} necessary for generating the target torque Pi _ETV calculated by the target torque calculation unit 1b. The target flow rate Q _{TH_TGT} is a target value of the mass flow rate of air passing through the throttle valve 24, and the target opening degree θ _TH of the throttle valve 24 is set based on the target flow rate Q _{TH_TGT} calculated here. As shown in FIG. 2, the target flow rate calculation unit 1d is provided with a target charging efficiency calculation unit 1e, a target in-cylinder air amount calculation unit 1f, and a flow rate calculation unit 1g.

The target charging efficiency calculation unit 1e calculates a target charging efficiency Ec _TGT corresponding to the target torque Pi _ETV transmitted from the target torque calculation unit 1b. Here, for example, the target charging efficiency Ec _TGT is calculated on the basis of a correspondence map, a mathematical expression or the like of the target torque Pi _ETV set in advance and the target charging efficiency Ec _TGT . The target charging efficiency Ec _TGT calculated here is transmitted to the target in-cylinder air amount calculation unit 1f.
Symbol Ec means filling efficiency. Filling efficiency is the normal volume of air filled in the cylinder during one intake stroke (one stroke until the piston 16 moves from top dead center to bottom dead center). And then divided by the cylinder volume. The charging efficiency corresponds to the amount of air introduced into the cylinder in the stroke, and the target charging efficiency Ec _TGT is a target value of the charging efficiency and corresponds to the target air amount. Hereinafter, the charging efficiency Ec corresponding to the amount of air actually introduced into the cylinder of the engine 10 is referred to as an actual charging efficiency Ec.

The target in-cylinder air amount calculation unit 1f performs a calculation for converting the target charging efficiency Ec _TGT calculated by the target charging efficiency calculation unit 1e into a target value Qc _TGT of the air amount introduced into the cylinder. Here, for example, the target value Qc _TGT is obtained on the basis of a correspondence map, a mathematical expression, or the like between the target charging efficiency Ec _TGT and the target value Qc _TGT set in advance. The target value Qc _TGT calculated here is transmitted to the flow rate calculation unit 1g.

The flow rate calculation unit 1g calculates a target flow rate of fresh air Q _{TH_TGT} that is a target value of the air amount desired to pass through the throttle valve 24 from a target value Qc _{TGT of the} air amount introduced into the cylinder. Here, the target flow rate Q _{TH_TGT} is calculated on the basis of a preset physical model, mathematical expression, etc. in consideration of the intake air delay resulting from the volume of the surge tank 21 and the like. The target flow rate Q _{TH_TGT} calculated here is transmitted to the third calculation unit 3.

[2-2. Second calculation unit]
The second calculation unit 2 (second calculation means) calculates the ratio of the downstream pressure equivalent value to the upstream pressure equivalent value of the throttle valve 24 as the actual pressure ratio B. Here, the actual pressure ratio B accurately reflects the actual pressure state of the intake passage 25 in the pressure ratio (P _IM / P _BP ) of the throttle valve section described above. In the present embodiment, the actual pressure ratio B is calculated in consideration of the effect of pressure loss in the vicinity of the throttle body 23 and in the intake passage 25.

The upstream pressure equivalent value related to the calculation of the actual pressure ratio B means the pressure of air immediately before passing through the throttle valve 24, or a pressure corresponding thereto, for example, the upstream pressure P _BP detected by the atmospheric pressure sensor 26. Is included in this. On the other hand, in the present embodiment, in consideration of the pressure change by the intake pressure loss, corrected upstream pressure P _{TH_U} the upstream pressure P _BP were corrected detected by the atmospheric pressure sensor 26 is used.

The downstream pressure equivalent value means a pressure corresponding pressure, or to the air immediately after passing through the throttle valve 24, for example, downstream pressure P _IM detected by the intake manifold pressure sensor 22 is included. In the present embodiment, the downstream pressure _PIM is used as it is as the downstream pressure equivalent value. If the throttle valve 24 and the mounting position of the intake manifold pressure sensor 22 are separated from each other, a value obtained by correcting the downstream pressure _PIM may be set as the downstream pressure equivalent value.

As shown in FIG. 2, the second calculation unit 2 is provided with an upstream pressure calculation unit 2a and an actual pressure ratio calculation unit 2b.
Upstream pressure calculating unit 2a is for upstream pressure P _BP detected by the atmospheric pressure sensor 26, engine speed Ne, based on the actual charging efficiency Ec and the maximum charging efficiency Ec _MAX, calculates a corrected upstream pressure P _{TH_U.} The actual charging efficiency Ec is calculated based on, for example, the air flow rate Q _IN detected by the air flow sensor 27, and the maximum charging efficiency Ec _MAX is calculated according to, for example, the engine speed Ne. The maximum charging efficiency Ec _MAX is a value obtained by converting the above-described maximum torque Pi _MAX into a charging efficiency (air amount).

The upstream pressure calculation unit 2a calculates a reference intake pressure loss T _PRSLOSSWOT when the throttle is fully opened, which is estimated from the engine speed Ne, based on the relationship shown in FIG. 5, for example. The reference intake pressure loss T _PRSLOSSWOT when the throttle is fully open increases as the engine speed Ne increases, and the increasing gradient also increases as the engine speed Ne increases.

Further, the upstream pressure calculation unit 2a calculates the intake pressure loss P _LOSS by multiplying the reference intake pressure loss T _PRSLOSSWOT by the ratio (Ec / Ec _MAX ) of the actual charging efficiency Ec to the maximum charging efficiency Ec _MAX . Since the maximum charging efficiency Ec _MAX is a parameter having a value corresponding to the amount of air introduced into the engine 10 when the throttle is fully opened, the ratio of the actual charging efficiency Ec to the maximum charging efficiency Ec _MAX corresponds to the opening ratio of the throttle valve 24. Value. Therefore, the intake pressure loss P _LOSS calculated here is obtained by converting the reference intake pressure loss T _PRSLOSSWOT into the pressure loss amount at the throttle opening at that time.

Furthermore, the upstream pressure calculating unit 2a, an atmospheric pressure correcting minus the intake pressure loss P _LOSS from the detected upstream pressure P _BP sensor 26 upstream pressure P _{TH_U} (throttle upstream _{pressure, P TH_U = P BP -P LOSS} ) Calculate as The corrected upstream pressure P _{TH_U} calculated here is transmitted to the actual pressure ratio calculation unit 2b.

Actual pressure ratio calculation unit 2b is based on has been a downstream pressure P _IM detected by correcting the upstream pressure P _{TH_U} and intake manifold pressure sensor 22 calculated by the upstream pressure calculating unit 2a, it is intended for calculating the actual pressure ratio B. Actual pressure ratio B is given as the ratio of the downstream pressure _{P IM (B = P IM /} P TH_U) for correcting the upstream pressure P _{TH_U.}

In addition, the actual pressure ratio calculation unit 2b is provided with a limiter for limiting the change amount (change amount per unit time) for each calculation cycle as means for suppressing the sudden change of the actual pressure ratio B calculated here. It is done. For example, the actual pressure ratio calculated in the previous calculation cycle is set to B _(n-1) , the actual pressure ratio calculated in the current calculation cycle is set to B _(n) , and the allowable change amount for each calculation cycle is set. When B ₀ is set, if the actual pressure ratio B _(n) of this time is larger than the previous actual pressure ratio B _(n-1) by the allowable change amount B ₀ or more, the actual pressure ratio B ₍ Substitute B _(n-1) + B ₀ for _n) . Conversely, if the current actual pressure ratio B _(n) is reduced allowable change B ₀ or more than the previous actual pressure ratio B _(n-1) is, in this actual pressure ratio B _(n) Substitute B _(n-1) -B ₀ .

Note that the value of the allowable change amount B ₀ may be a preset fixed value, or the actual pressure ratio B _{(n) of} this time in consideration of the relationship between the flow velocity of intake air and the pressure ratio as shown in FIG. Also, it may be set when at least one (or both) of the previous actual pressure ratio B _(n-1) is equal to or greater than a predetermined value close to 1. Alternatively, the allowable change amount B ₀ may be set to increase as the actual pressure ratio B _(n) this time is closer to 1. The actual pressure ratio B calculated here is transmitted to the third calculation unit 3.

[2-3. Third operation unit]
The third calculation unit 3 (third calculation means) corrects the target opening degree θ _TH of the throttle valve 24 set according to the actual pressure ratio B based on the pressure ratio equivalent value A. The calculation accuracy of the actual pressure ratio B depends on the detection accuracy of sensors such as the intake manifold pressure sensor 22 and the atmospheric pressure sensor 26, whereas the calculation accuracy of the pressure ratio equivalent value A does not depend on the detection accuracy of these sensors. In the present embodiment, the third calculation unit 3 sets a reference flow velocity range (reference flow velocity value region) of the actual pressure ratio B based on the pressure ratio equivalent value A, and the air flow velocity V from the actual pressure ratio B and the reference flow velocity region. Is calculated.

Here, the relationship between the pressure ratio equivalent value A and the actual pressure ratio B of the actual throttle valve portion is graphed and shown in FIG. This graph shows the relationship between the pressure ratio equivalent value A and the actual pressure ratio B when the engine speed Ne and the air-fuel ratio are constant and the valve lift amount (control angle θ _VVL ) of the intake valve 14 is changed. It is a plot.

The horizontal and vertical axes of the graph are the pressure ratio equivalent value A and the actual pressure ratio B, respectively, and the white circles arranged in dotted lines are the points where the pressure ratio equivalent value A and the actual pressure ratio B are the same value (actual pressure Ratio B = point on the straight line graph of pressure ratio equivalent value A). The thin broken line, thin solid line, thick broken line, and thick solid line graphs in FIG. 6A increase the valve lift amount of the intake valve 14 in four stages of L ₁ , L ₂ , L ₃ , and L ₄ , respectively. Is the result of when. Each of these four graphs has a shape substantially along a dotted white circle. That is, a correlation is recognized between the pressure ratio equivalent value A and the actual pressure ratio B, and the correlation does not depend on the valve lift amount.

  In the present embodiment, using the correlation between the pressure ratio equivalent value A and the actual pressure ratio B, the flow velocity V of the intake flow is not calculated from the actual pressure ratio B alone, but the flow velocity V is calculated using both. Is calculated. As shown in FIG. 2, the third calculation unit 3 includes an estimated flow rate calculation unit 3a, a reference flow rate calculation unit 3b, a flow rate correction unit 3c, and an opening setting unit 3d.

The estimated flow velocity calculation unit 3a (estimated flow velocity calculation means) calculates the estimated flow velocity V _{B of} air based on the actual pressure ratio B. In the estimated flow velocity calculation unit 3a, a map, a mathematical expression, and the like that prescribe the change in flow velocity due to the front-rear pressure ratio of the throttle valve unit are recorded in advance. For example, the estimated flow velocity V _B corresponding to the actual pressure ratio _B is calculated based on the relationship between the pressure ratio and the flow velocity as shown in FIG. The estimated flow velocity V _B calculated here is transmitted to the flow velocity correction unit 3c.

As shown in FIG. 3, the flow rate of the compressible fluid flowing through the throttle in the pipe (fluid whose density changes according to the pressure change) is the pressure ratio before and after the throttle (ratio of the downstream pressure to the upstream pressure). Decrease with increasing size. On the other hand, when the pressure ratio becomes smaller than the critical pressure ratio Z ₀ , the flow velocity becomes constant. Based on such characteristics, in the graph of FIG. 3, the pressure ratio definition region is set to a range of 0 to 1, and the flow rate is set to 0 when the pressure ratio is 1. In addition, the flow rate increases as the pressure ratio decreases, and when the pressure ratio is less than the critical pressure ratio Z ₀ , the relationship between the pressure ratio and the flow rate is shown such that the flow rate becomes the upper limit value V ₀ corresponding to the speed of sound. ing.

The reference flow velocity calculation unit 3b (reference flow velocity calculation means) calculates a reference flow velocity region of air passing through the throttle valve 24 based on the pressure ratio equivalent value A. The reference flow velocity range means a range of values where the actual pressure ratio B should exist. Here, the reference velocity range is defined by the center value V _CEN and the width V _WDT (distance from the center value V _CEN ), and each of the center value V _CEN and the width V _WDT is set according to the pressure ratio equivalent value A. Is done.

In the reference flow velocity calculation unit 3b, the correspondence between the pressure ratio equivalent value A and the center value V _CEN as shown in FIG. 7A, and the pressure ratio equivalent value A and the width V as shown in FIG. Corresponding relationships with _WDT are stored in advance, and center value V _CEN and width V _WDT are calculated based on these corresponding relationships. The relationship between the pressure ratio equivalent value A and the center value V _CEN shown in FIG. 7A may be the same as the relationship between the pressure ratio and the flow velocity shown in FIG. 3, or different ones may be prepared separately. .

In the graph shown in FIG. 7 (b), the width V _WDT has a positive value when the pressure ratio equivalent value A is in the range of the critical pressure ratio A ₀ or more and 1 or less, and the other range (the pressure ratio equivalent value is the critical pressure). The relationship between the pressure ratio equivalent value A and the width V _WDT is determined so that the width V _WDT becomes 0 in the range of the ratio A less than ₀ ). The value of the width V _WDT is set to 0 when A = A ₀ and A = 1, and is set to take the maximum value when A = A ₁ (A ₀ <A ₁ <1). .

Focusing on a region where the pressure ratio equivalent value A is close to 1 (for example, a range of A> A ₁ ), the value of the width V _WDT decreases as the pressure ratio equivalent value A approaches 1 and gradually approaches 0. That is, since the change amount (change gradient) of the flow velocity V is large in the region where the pressure ratio equivalent value A is close to 1, the change is strongly suppressed. In addition, when lines L ₁ and L ₂ of flow velocity values obtained by adding and subtracting the value of the width V _WDT are drawn in the vertical direction of the solid line graph of FIG. 7A, a line L ₁ indicating the upper limit and a line L ₂ indicating the lower limit are drawn. A region sandwiched between (hatching region) is a range of the reference flow velocity region.

The flow rate correction unit 3c (correction unit, flow rate correction unit) determines whether or not the estimated flow rate V _B calculated by the estimated flow rate calculation unit 3a exists in the reference flow rate range, and based on the determination result, the estimated flow rate V _B Is to correct. Here, the correction calculation is performed so that the estimated flow velocity V _B falls within the reference flow velocity, and the final flow velocity V for setting the target throttle opening θ _TH is calculated. The state of the estimated flow velocity V _B is one of the following three types.
(A) The estimated flow velocity V _B exceeds the upper limit of the reference flow velocity range (V _CEN + V _WDT <V _B )
(B) The estimated flow velocity V _B is below the lower limit of the reference flow velocity range (V _B <V _CEN −V _WDT )
(C) The estimated flow velocity V _B is within the reference flow velocity range (V _CEN −V _WDT ≦ V _B ≦ V _CEN + V _WDT )

In the case of (C) above, it is determined that the estimated flow velocity V _B is within the appropriate range, and the flow velocity correction unit 3c substitutes the value of the estimated flow velocity V _{B for} the flow velocity V and transmits the value to the opening setting unit 3d. That is, in this case, the estimated flow velocity V _B is not corrected. On the other hand, in the case of the above (A), it is determined that the estimated flow velocity V _B is excessive, and the flow velocity correction unit 3c substitutes the added value of the center value V _CEN and the width V _WDT into the flow velocity V to set the opening degree. Transmitted to the unit 3d. In the case of (B) above, it is determined that the estimated flow velocity V _B is too small, and the flow velocity correction unit 3c substitutes the value obtained by subtracting the width V _WDT from the center value V _CEN into the flow velocity V, and the opening degree. This is transmitted to the setting unit 3d. Therefore, the flow velocity V transmitted to the opening setting unit 3d is limited to a value within the reference flow velocity region. As described above, the flow velocity correction unit 3c functions as a correction unit that corrects the estimated flow velocity V _B based on the pressure ratio equivalent value A.

The opening degree setting unit 3d (opening degree setting means) is based on the target flow rate Q _{TH_TGT} calculated by the flow rate calculation unit 1g of the target flow rate calculation unit 1d and the flow velocity V transmitted from the flow velocity correction unit 3c. The target opening area S is calculated. For example, as shown in FIG. 2, the target opening area S is obtained by dividing the target flow rate Q _{TH_TGT} by a value obtained by multiplying the flow velocity V by the correction coefficient M _MACH . The correction coefficient M _MACH is a value that is calculated in consideration of the change in air density due to temperature. For example, the correction upstream pressure P calculated by the intake air temperature AT detected by the intake air temperature sensor 31 and the upstream pressure calculation unit 2a. Set based on _{TH_U} .

In the present embodiment, based on the relationship shown in FIG. 8, the mass flow velocity (product of the flow velocity and the density) of the intake air flow is calculated according to the intake air temperature AT, and the corrected upstream pressure _{PTH_U} ratio with respect to the standard atmospheric pressure is calculated. A value obtained by multiplying the mass flow rate by a predetermined coefficient is calculated as the correction coefficient M _MACH . The target opening area S calculated here is transmitted to the throttle opening degree control unit 4.

[2-4. Throttle opening control unit]
The throttle opening degree control unit 4 outputs a control signal to the throttle valve 24 so that the opening degree of the throttle valve 24 becomes equal to the target opening area S calculated in the third calculation unit 3. Here, for example, the target opening voltage E is calculated based on a preset correspondence map between the target opening area S and the target opening voltage E, a mathematical expression, or the like, and the target opening voltage E is used as a control signal for the throttle valve 24. Is output. The relationship between the target opening area S and the target opening voltage E is defined according to the structure, shape, type, etc. of the throttle valve 24. For example, in the case of the throttle valve 24 having the characteristic of opening the passage more greatly as the opening voltage is higher, the target opening voltage E may be increased as the target opening area S is larger, as shown in FIG. .

The throttle valve 24 receives the control signal from the throttle opening control unit 4 to control the throttle opening, and the target opening area S is realized. Thus, when the flow rate of the air passing through the throttle valve 24 becomes the target flow rate Q _{TH_TGT} , the actual charging efficiency Ec of the cylinder becomes the target charging efficiency Ec _TGT , and the output torque of the engine 10 becomes the target torque Pi _ETV . The engine control device 5 performs the intake air amount control in this way.

[3. Action, effect]
As shown in FIG. 6A, the pressure ratio equivalent value A is correlated with the actual pressure ratio B of the throttle valve portion. Based on this correlation, the engine control device 5 described above uses these two types of indicators having different calculation processes, and corrects the target throttle opening θ _TH calculated from the actual pressure ratio B based on the pressure ratio equivalent value A. To do. The actual pressure ratio B is a value calculated by the actual pressure ratio calculation unit 2b of the second calculation unit, and the pressure ratio equivalent value A is calculated by the first calculation unit 1 separately from the actual pressure ratio B. This is a value calculated by the part 1c.

By calculating such one index with the other index, it is possible to calculate the target opening area S with high accuracy, and an appropriate target opening of the throttle valve 24 can be set. Further, in the engine control device 5 described above, fluctuations and changes in the actual pressure ratio B are suppressed by the pressure ratio equivalent value A. Therefore, the control accuracy and accuracy of the target throttle opening θ _TH can be improved, and the target throttle opening θ _TH can be appropriately controlled with respect to the target torque Pi _ETV .

In the engine control device 5 described above, the actual pressure ratio calculation unit 2b is provided with a limiter, and fluctuations and changes in the actual pressure ratio B are limited to a double. Thereby, unintended sudden fluctuations in the target throttle opening _θTH can be more reliably suppressed, and the controllability of the throttle valve 24 can be improved.
Further, in the engine control device 5 described above, the estimated flow velocity V _B is calculated based on the actual pressure ratio B, and the estimated flow velocity V _B is corrected based on the pressure ratio equivalent value A. As a result, it is possible to suppress sudden changes in the estimated flow velocity V _B , improve the estimation accuracy of the flow velocity, and increase the reliability of the target throttle opening θ _{TH with} respect to the target torque Pi _ETV .

In the control region where the throttle opening is relatively large, the actual pressure ratio B approaches 1, and the value of the estimated flow velocity V _B tends to fluctuate greatly with a slight change in the actual pressure ratio B. That is, the target opening area S of the throttle valve 24 is likely to change greatly, and the controllability of the throttle valve 24 may be reduced.
In contrast, according to the present engine control apparatus 5, it is possible to reduce the fluctuation range of the values of the estimated velocity V _B. Therefore, the controllability of the throttle valve 24 can be ensured even in a control region where the throttle opening is relatively large. For example, even when the actual pressure ratio B has changed due to the detection error of the sensor. The throttle valve 24 can be appropriately controlled.

  In the engine control device 5 described above, the range in which the actual pressure ratio B should exist is calculated as the reference flow velocity region based on the pressure ratio equivalent value A. This reference flow velocity range is a range that is set based on information related to engine torque, not information on pressure detected by the intake manifold pressure sensor 22 or the atmospheric pressure sensor 26. Therefore, even if the detection information of these pressure sensors 22 and 26 is inaccurate, an appropriate range can be set, and the control reliability of the throttle valve 24 can be improved.

Further, by providing the width V _WDT in the reference flow velocity region, a minute change in the actual pressure ratio B can be allowed. That is, in the determination by the flow velocity correction unit 3c, when the estimated flow velocity V _B is within the reference flow velocity region, the estimated flow velocity V _B becomes the flow velocity V. Thereby, flexibility can be given to control of the throttle valve 24, and controllability can be further improved. On the other hand, when the estimated flow velocity V _B is outside the range of the reference flow velocity range, either the upper limit value (V _CEN + V _WDT ) or the lower limit value (V _CEN −V _WDT ) that defines the reference flow velocity range is the flow velocity V. . Thereby, the deviation of the estimated flow velocity V _B from the central value V _{CEN of the} flow velocity as shown in FIG. 7 can be prevented.

In the engine control device 5 described above, for example, as shown in FIG. 7B, the set value of the width V _WDT gradually approaches 0 as the pressure ratio equivalent value A approaches 1. By setting the width V _WDT as described above, it is possible to enhance the effect of suppressing the fluctuation of the estimated flow velocity V _B when the estimated flow velocity V _B is easily changed. As a result, the stability of the flow velocity V related to the calculation of the target opening area S can be improved, and the controllability of the throttle valve 24 can be improved.

In addition, when the maximum torque Pi _MAX is calculated by the maximum torque calculation unit 1a, if the maximum torque equivalent value is calculated according to the valve lift amount and valve timing, it corresponds to the pressure ratio calculated from the maximum torque Pi _MAX. Since the correlation between the value A and the actual pressure ratio B increases, the target opening of the throttle valve 24 can be accurately set according to the control state of the intake valve 14 and the exhaust valve 15.

Regarding the calculation method of the pressure ratio equivalent value A, the above-described control device calculates the pressure ratio equivalent value A using the maximum torque Pi _MAX and the target torque Pi _ETV at that time. These maximum torque Pi _MAX and target torque Pi _ETV are parameters that can be used in torque-based control other than intake amount control such as control of fuel injection amount, injection timing, and ignition timing, for example. There is an advantage that the control program and the algorithm can be simplified easily.

Regarding the calculation of the maximum torque Pi _MAX , the maximum torque calculation unit 1a basically calculates the torque generated by the engine 10 as the maximum torque Pi _MAX when the ignition timing is set to the optimum 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 B can be increased, and the calculation accuracy of the target opening of the throttle valve 24 can be improved.

On the other hand, even in an operating state in which the ignition timing cannot be set to the optimal ignition timing, the predetermined ignition timing is set close to the advance angle close to the optimal ignition timing, and the generated torque becomes the maximum torque Pi _MAX at the predetermined ignition timing. Therefore, the correlation between the pressure ratio equivalent value A and the actual pressure ratio B can be increased, and the calculation accuracy of the target opening of the throttle valve 24 can be improved.
Note that there is also an advantage that the calculation configuration can be simplified by calculating the pressure ratio equivalent value A using the maximum torque Pi _MAX of the engine 10 and the target torque Pi _ETV .

Furthermore, for example, when the maximum torque Pi _MAX is calculated under a condition of a constant predetermined air / fuel ratio such as a stoichiometric air / fuel ratio or an output air / fuel ratio, it is possible to eliminate the influence of the difference in torque derived from the air / fuel ratio, which corresponds to the pressure ratio. The correlation between the value A and the actual pressure ratio B 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 above-described control device, the pressure ratio equivalent value A is calculated using the maximum torque Pi _MAX and the target torque Pi _ETV of the engine 10, but the same applies by using the amount of air introduced into the cylinder instead of the torque. It is also possible to perform the calculation. For example, instead of the maximum torque Pi _MAX and the target torque Pi _ETV of the above-described embodiment, the second pressure ratio equivalent value A ′ is calculated using the maximum filling efficiency Ec _MAX and the target filling efficiency Ec _TGT, and the second pressure It can be considered that the reference flow velocity region is set based on the ratio equivalent value A ′.

The maximum charging efficiency Ec _MAX is the charging efficiency corresponding to the maximum torque Pi _MAX in the above-described embodiment, and is based on the amount of air required to generate the maximum torque Pi _MAX at the engine speed Ne at that time. It is the calculated charging efficiency (charging efficiency when the throttle is fully opened). The target charging efficiency Ec _TGT is a charging efficiency corresponding to the target torque Pi _ETV, a charging efficiency is calculated based on the amount of air required to generate the target torque Pi _ETV engine 10. Using these parameters, the ratio of the target charging efficiency Ec _TGT to the maximum charging efficiency Ec _MAX can be set to the second pressure ratio equivalent value A ′ (A ′ = Ec _TGT / Ec _MAX ).

Here, FIG. 6B illustrates the relationship between the second pressure ratio equivalent value A ′ and the actual pressure ratio B of the actual throttle valve portion. Similar to FIG. 6A, this graph shows the second pressure ratio equivalent value A ′ and the actual pressure when the engine speed Ne and the air-fuel ratio are constant and the valve lift amount of the intake valve 14 is changed. The relationship with the ratio B is plotted.
Each of the four graphs with different valve lifts has a shape along the dotted white circle, and the correlation between the second pressure ratio equivalent value A ′ and the actual pressure ratio B does not depend on the valve lift amount. Is recognized. Therefore, the throttle opening degree θ _TH can be calculated using the second pressure ratio equivalent value A ′ together with the actual pressure ratio B in the same manner as the pressure ratio equivalent value A.

  FIG. 10 illustrates a block configuration of an engine control device 5 ′ as a modified example for performing such calculation. The engine control device 5 ′ is provided with a first calculation unit 1 ′, a second calculation unit 2, a third calculation unit 3, and a throttle opening control unit 4, which replaces the target torque calculation unit 1b in the above-described embodiment. Is provided with a target filling efficiency calculation unit 1e. In addition, about the element demonstrated by the above-mentioned embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

The first calculation unit 1 ′ (first calculation means) calculates the second pressure ratio equivalent value A ′. The first calculation unit 1 'includes a maximum torque equivalent value calculation unit 1a', a target torque equivalent value calculation unit 1e ', and a pressure ratio equivalent value calculation unit 1c'.
The maximum torque equivalent value calculation unit 1a ′ calculates the maximum charging efficiency Ec _MAX based on the engine speed Ne detected (or calculated) by the crank angle sensor 30. In the maximum torque equivalent value calculation unit 1a ', for example, a map or a mathematical formula that defines the correspondence relationship between the engine speed Ne and the maximum charging efficiency Ec _MAX as shown by a solid line in FIG. 4 is stored in advance. Based on the relationship, the maximum filling efficiency Ec _MAX is calculated. The maximum charging efficiency Ec _MAX calculated here is transmitted to the pressure ratio equivalent value calculation unit 1c ′.

Further, the target torque equivalent value calculation unit 1e ′ calculates the target torque Pi _ETV based on the engine speed Ne detected (or calculated) by the crank angle sensor 30 and the operation amount θ _AC detected by the accelerator pedal sensor 29. The charging efficiency calculated based on the air amount corresponding to the target torque Pi _ETV is calculated as the target charging efficiency Ec _TGT . The target charging efficiency Ec _TGT calculated here is transmitted to the pressure ratio equivalent value calculation unit 1c ′ and the target flow rate calculation unit 1d ′.

The pressure ratio equivalent value calculation unit 1c ′ is based on the maximum charging efficiency Ec _MAX calculated by the maximum torque equivalent value calculation unit 1a ′ and the target charging efficiency Ec _TGT calculated by the target torque equivalent value calculation unit 1e ′. The two pressure ratio equivalent value A ′ is calculated. The second pressure ratio equivalent value A ′ is given as a ratio (B = Ec _TGT / Ec _MAX ) of the target filling efficiency Ec _TGT to the maximum filling efficiency Ec _MAX . The second pressure ratio equivalent value A ′ calculated here is transmitted to the reference flow velocity calculation unit 3b.

Also in the engine control device 5 'configured as described above, the second pressure ratio equivalent value correlated with the actual pressure ratio B of the actual throttle valve unit in the pressure ratio equivalent value calculation unit 1c' of the first calculation unit 1 '. A ′ is calculated. Further, the reference flow velocity calculation unit 3b of the third calculation unit 3 calculates the reference flow velocity region of the air passing through the throttle valve 24 based on the second pressure ratio equivalent value A ′. Thereby, the fluctuation of the actual pressure ratio B can be suppressed by the second pressure ratio equivalent value A ′, the control accuracy and accuracy of the target throttle opening θ _TH can be improved, and the target torque Pi _ETV The target throttle opening θ _TH can be appropriately controlled.

Further, as shown in FIG. 6B, since the correlation with the actual pressure ratio B of the throttle valve portion is recognized in the second pressure ratio equivalent value A ′, a highly accurate target is obtained as in the above-described embodiment. The opening area S can be calculated by the opening setting unit 3d, and an appropriate target opening of the throttle valve 24 can be set. Even when the maximum charging efficiency Ec _MAX or the target charging efficiency Ec _TGT is used, the same calculation as that when the maximum torque Pi _MAX or the target torque Pi _ETV of the engine 10 is used is possible. Simplification is easy.

Further, conceivable that upon operation of the maximum charging efficiency Ec _MAX 'in the maximum torque equivalent value calculation section 1a of the' first arithmetic unit 1, a configuration that calculates the valve lift, the maximum charging efficiency Ec _MAX corresponding to the valve timing It is done. In this case, as indicated by broken lines in FIG. 4, a graph corresponding to a plurality of control angles θ _VVL and phase angles θ _VVT is set in advance, so that the maximum corresponding to the control angle θ _VVL and phase angles θ _VVT is obtained. Calculation of filling efficiency Ec _MAX is possible. Thereby, the correlation between the pressure ratio equivalent value A and the actual pressure ratio B can be strengthened, and the controllability of the throttle valve 24 can be further improved.

[4-2. Others]
In the above embodiment, the actual pressure ratio B is always corrected with the pressure ratio equivalent value A, but the timing for performing the correction calculation of the actual pressure ratio B with the pressure ratio equivalent value A is not limited to this. For example, the flow velocity V is normally calculated using only the actual pressure ratio B, and correction is performed using the pressure ratio equivalent value A when a fail signal is input from either the intake manifold pressure sensor 22 or the atmospheric pressure sensor 26. It is good also as such a structure. This makes it possible to perform accurate throttle control even when each sensor malfunctions or breaks down, thereby improving the reliability of intake air amount control.

Moreover, in the above-described embodiment, as illustrated in FIGS. 7A and 7B, the example in which the estimated flow velocity V _B is corrected using the reference flow velocity region calculated from the pressure ratio equivalent value A is illustrated. The flow velocity correction method is not limited to this. For example, it is conceivable to correct the value of the actual pressure ratio B according to the pressure ratio equivalent value A using the correlation between the pressure ratio equivalent value A and the actual pressure ratio B as shown in FIG. .
In this case, it is conceivable that the reference pressure ratio region is set based on the pressure ratio equivalent value A instead of the reference flow velocity region, and the correction calculation is performed so that the actual pressure ratio B is within the reference pressure ratio region. The relationship between the reference pressure ratio region set based on the pressure ratio equivalent value A and the actual pressure ratio B is shown in FIG. Here, as in the above-described embodiment, an example in which the reference pressure ratio region is set in a range where the pressure ratio equivalent value A is in the range of the critical pressure ratio A ₀ to 1 is illustrated. The solid line graph in FIG. 11 is a straight line with a slope of 1 where the pressure ratio equivalent value A and the actual pressure ratio B have the same value.

When a line L ₃ indicating the upper limit value of the actual pressure ratio B and a line L ₄ indicating the lower limit value are drawn above and below the straight line graph, a region sandwiched between these lines (hatched region) becomes the reference pressure ratio region. . Therefore, similarly to the determination method in the flow velocity correction unit 3c described above, when the actual pressure ratio B exists in this reference pressure ratio region, the estimated flow velocity V _B is calculated using the actual pressure ratio B as it is, and the reference pressure is calculated. If it exists outside the ratio range, the estimated flow velocity V _B can be calculated using the pressure ratio clipped at the line L ₃ or the line L ₄ .

Even if such a calculation method is used, the fluctuation of the actual pressure ratio B can be suppressed, the control accuracy and accuracy of the target throttle opening θ _TH can be improved, and the target torque Pi _ETV can be improved. Thus, the target throttle opening θ _TH can be appropriately controlled. Further, by correcting the actual pressure ratio B prior to the calculation of the flow velocity, the control configuration can be simplified and the calculation load can be reduced.

In the embodiment described above, the calculation method of the maximum torque Pi _MAX has been described mainly focusing on the relationship between the engine speed Ne and the maximum torque Pi _MAX as shown in FIG. However, the maximum torque Pi _MAX of the engine 10 changes not only according to the engine speed Ne but also according to the ignition timing, the valve lift amount, the valve timing, and the air-fuel ratio as described above. Therefore, the maximum torque Pi _MAX may be calculated or corrected according to the valve lift amount and valve timing at the time when the maximum torque Pi _MAX is calculated by the maximum torque calculator 1a. Thereby, the correlation between the pressure ratio equivalent value A and the actual pressure ratio B can be further increased, and the controllability of the throttle valve 24 can be further improved.

On the other hand, even if the valve lift amount and valve timing at the time of calculation are not used, the correlation between the pressure ratio equivalent value A and the actual pressure ratio B is ensured. For example, as shown in FIGS. 6A and 6B, the correlation between the pressure ratio equivalent value A and the actual pressure ratio B does not depend on the valve lift amount. Therefore, it is not always necessary to reflect the actual control angle θ _VVL and phase angle θ _VVT in the calculation of the maximum torque Pi _MAX .

The same applies to the ignition timing. The maximum torque Pi _MAX at the ignition timing at the time of calculation may be calculated, or the torque generated when ignition is performed at the optimal ignition timing is set to the maximum torque Pi _MAX. Alternatively, the maximum torque Pi _MAX may be used as the torque generated when the ignition timing is slightly delayed from the optimal ignition timing in consideration of the possibility of knocking. The correlation between the pressure ratio equivalent value A and the actual pressure ratio B is strengthened most when the ignition is performed at the optimal ignition timing, but even in other cases, the pressure ratio equivalent value A and the actual pressure ratio B A correlation can be recognized between the two.

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 _ETV 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 A ′ may be calculated using the air amount (air volume or mass) instead of the charging efficiency in the above-described modification.

1 1st operation part (1st operation means)
1c Pressure ratio equivalent value calculation unit 1d Target flow rate calculation unit 2 Second calculation unit (second calculation means)
2b Actual pressure ratio calculation unit 3 Third calculation unit (third calculation means)
3a Estimated flow velocity calculation unit (estimated flow velocity calculation means)
3b Reference velocity calculation unit (reference velocity calculation means)
3c Flow velocity correction unit (correction means, flow velocity correction means)
3d Opening setting unit (opening setting means)
4 Throttle opening controller 5 Engine controller

Claims (10)

First calculation means for calculating a ratio of a target torque equivalent value of the engine to a maximum torque equivalent value of the engine as a pressure ratio equivalent value;
Second calculating means for calculating the ratio of the downstream pressure equivalent value to the upstream pressure equivalent value of the throttle valve as the actual pressure ratio;
3. An engine control apparatus comprising: third calculation means for correcting a target opening of the throttle valve set according to the actual pressure ratio based on the pressure ratio equivalent value. The third computing means is
An estimated flow velocity calculating means for calculating an estimated flow velocity of air passing through the throttle valve based on the actual pressure ratio;
Correction means for correcting the estimated flow velocity based on the pressure ratio equivalent value;
2. The engine control device according to claim 1, further comprising: an opening setting unit that sets a target opening of the throttle valve based on the estimated flow velocity corrected by the correction unit. The correction means is
A reference flow velocity calculating means for calculating a reference flow velocity value range of air passing through the throttle valve based on the pressure ratio equivalent value;
The engine control device according to claim 2, further comprising: a flow velocity correction unit that corrects the estimated flow velocity value so as to be within the reference flow velocity value range. The reference flow velocity calculation means sets a center value of the reference flow velocity value area and a width from the center value based on the pressure ratio equivalent value, and sets the width narrower as the pressure ratio equivalent value is larger. The engine control apparatus according to claim 3, wherein the engine control apparatus is characterized in that: The third computing means is
Actual pressure ratio correcting means for correcting the actual pressure ratio based on the pressure ratio equivalent value;
Second estimated flow velocity calculating means for calculating an estimated flow velocity of air passing through the throttle valve based on the actual pressure ratio corrected by the actual pressure ratio correcting means;
The engine control device according to any one of claims 1 to 4, further comprising second opening setting means for setting a target opening of the throttle valve based on the estimated flow velocity. The engine control according to any one of claims 1 to 5, wherein the first calculation means calculates the maximum torque equivalent value in accordance with a valve lift amount or a valve timing of an intake / exhaust valve. apparatus. The first calculation means calculates a torque generated in the engine with the maximum air amount introduced into the engine according to the engine speed as the maximum torque equivalent value, and based on an output request to the engine The engine control device according to claim 1, wherein the set target torque is calculated as the target torque equivalent value. 8. The engine control device according to claim 7, wherein the first calculation means calculates a torque generated in the engine when the ignition timing is an optimal ignition timing as the maximum torque equivalent value. The engine according to claim 7 or 8, wherein the first calculation means calculates a maximum torque generated in the engine during combustion at a predetermined air-fuel ratio set in advance as the maximum torque equivalent value. Control device. The first calculation 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 air amount as the target torque equivalent value. The engine control device according to any one of claims 1 to 9, wherein

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