JP2016118149A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of accurately estimating a quantity of intake air introduced into an internal combustion engine provided with a variable valve gear mechanism.SOLUTION: An internal combustion engine control device comprises: target-value setting means setting a control angle which corresponds to a target value of a lift amount of an intake valve 7 from an operating state; control-angle detection means detecting a control angle from a reference position of a control member; lift-speed calculation means calculating a lift speed which is a variation of the control angle per unit time; lift-amount estimation means estimating the lift amount after a predetermined prediction period since calculation of the lift speed on the basis of the lift speed and the prediction period; and intake-air-quantity estimation means estimating a quantity of intake air taken in a combustion chamber of the internal combustion engine on the basis of the lift amount, the lift-speed calculation means calculating a deviation which is a difference between the control angle set by the target-value setting means and the control angle detected by the control-angle detection means and calculating the lift speed from speed characteristics representing a relation between the deviation and the lift speed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine that includes a variable valve mechanism and can accurately estimate an intake air amount introduced into an intake pipe injection type internal combustion engine.

  Conventionally, a technique for appropriately controlling an internal combustion engine by accurately obtaining an intake air amount sucked into a combustion chamber of the internal combustion engine is known. However, since it is difficult to directly detect the intake air amount, a general method is to detect the air flow rate in the intake system of the internal combustion engine with an air flow sensor and estimate the intake air amount based on the detection result. Has been used. In particular, in an internal combustion engine that injects fuel into the intake pipe before the intake valve is closed, it is necessary to more accurately estimate the intake air amount sucked into the combustion chamber at the time of fuel injection. Estimating is an important issue.

  In recent years, a variable valve mechanism has been developed that changes valve characteristics such as the lift amount of an intake valve or exhaust valve, opening / closing valve timing, and valve opening period in accordance with the rotational speed and load of an internal combustion engine (for example, Patent Documents). 1), and a technique for estimating the intake air amount in an internal combustion engine to which such a variable valve mechanism is applied has also been developed (see, for example, Patent Document 2).

  According to such estimation of the intake air amount, an effective stroke volume corresponding to a change in the operation state of the intake valve is calculated, and the intake air amount is calculated based on the effective stroke volume. Therefore, the intake air amount can be estimated more accurately.

  However, when the intake valve is operated so as to achieve the target lift amount according to the driving situation, a delay occurs until the target lift amount is reached. When the intake air amount is calculated with the target lift amount as the operating state of the intake valve in such a delay, that is, in a transient state, the actual intake valve lift amount is not reflected.

JP 2005-299536 A Japanese Patent No. 4760604

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a control device for an internal combustion engine that can accurately estimate the amount of intake air introduced into the internal combustion engine having a variable valve mechanism.

  A first aspect of the present invention that solves the above problem is a control device for an internal combustion engine including a variable valve mechanism that can change a lift amount of an intake valve in accordance with a control angle of a control member. Target value setting means for setting a control angle corresponding to the target value of the lift amount of the intake valve, control angle detection means for detecting a control angle from a reference position of the control member, and fluctuation of the control angle per unit time Lift speed calculation means for calculating a lift speed as a quantity, lift amount estimation means for estimating a lift quantity after the prediction period based on the lift speed and a predetermined prediction period from the time when the lift speed was calculated And an intake air amount estimating means for estimating an intake air amount sucked into the combustion chamber of the internal combustion engine based on the lift amount estimated by the lift amount estimating means, the lift speed calculating means A deviation that is a difference between the control angle set by the target value setting means and the control angle detected by the control angle detection means is calculated, and the lift speed is calculated from a speed characteristic that represents the relationship between the deviation and the lift speed. In the control device for the internal combustion engine.

  In the first aspect, in the variable valve mechanism that cannot directly obtain the lift speed, the lift speed can be obtained based on the deviation of the control angle. By obtaining the lift speed in this way, it is possible to estimate the lift amount of the intake valve after the prediction period. And, since the intake air amount is estimated based on the lift amount after the prediction period, the intake air amount takes into account that the lift amount of the variable valve mechanism operates later than the target control angle, The difference between the estimated intake air amount and the actual intake air amount can be reduced.

  According to a second aspect of the present invention, in the control apparatus for an internal combustion engine described in the first aspect, the lift speed calculation means uses different speed characteristics for the positive and negative deviations. The control apparatus for an internal combustion engine is characterized.

  In the second aspect, even if the control angle deviation is the same, the lift speed can be increased with higher accuracy in accordance with the direction in which the control member rotates in the variable valve mechanism in which the lift speed varies depending on the direction of rotation. Can be estimated.

  According to a third aspect of the present invention, in the control device for an internal combustion engine described in the first or second aspect, the lift speed calculation means is configured to respectively perform a case where the deviation increases and a case where the deviation decreases. The control apparatus for an internal combustion engine uses different speed characteristics.

  In the third aspect, even when the deviation of the control angle is the same, in the variable valve mechanism in which the lift speed differs depending on whether the deviation is increasing or decreasing, It is possible to estimate the lift speed with higher accuracy by using speed characteristics suitable for each time of decrease.

  According to a fourth aspect of the present invention, in the control device for an internal combustion engine described in any one of the first to third aspects, the lift speed calculation means calculates the lift speed for each predetermined period and for each period. The calculated lift speed is stored, and the lift amount estimating means calculates in the previous cycle in the delay time until the actual operation starts so that the lift amount of the intake valve becomes the target value. The control apparatus for an internal combustion engine is characterized in that the lift amount is estimated using the lift speed.

  In the fourth aspect, the lift speed can be estimated with higher accuracy in the variable valve mechanism having a delay time.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the internal combustion engine which can estimate the intake air amount introduced into an internal combustion engine provided with a variable valve mechanism with sufficient accuracy is provided.

1 is a schematic configuration diagram of an internal combustion engine and a control device for an internal combustion engine according to Embodiment 1. FIG. It is a graph which shows the characteristic of the lift amount of a VVL mechanism, and the characteristic of a lift amount and a VVL control angle. It is a figure which shows the processing flow in the control apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the processing flow in the control apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the processing flow in the control apparatus which concerns on Embodiment 1. FIG. It is a graph which shows the relationship between the VVL deviation used as the input of a lift speed calculation means, and the VVL speed used as an output. It is a graph which shows the time-sequential change of the amount of intake air, the opening degree of a throttle valve, the lift amount of an intake valve, and the pressure in an intake manifold. It is a graph which shows the speed characteristic used based on a VVL deviation. It is a figure which shows the processing flow in the control apparatus which concerns on Embodiment 2. FIG. It is a figure which shows the time difference until the lift amount of an intake valve actually starts moving after the target VVL is set. It is a figure which shows the processing flow in the control apparatus which concerns on Embodiment 3. FIG.

  Hereinafter, modes for carrying out the present invention will be described. In addition, description of embodiment is an illustration and this invention is not limited to the following description.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of an internal combustion engine and a control device for the internal combustion engine according to the present embodiment. In the figure, an intake pipe injection type multi-cylinder (for example, four-cylinder) gasoline engine (hereinafter referred to as engine 1), which is an example of the internal combustion engine of the present embodiment, is illustrated. As the internal combustion engine, not only an intake pipe injection multi-cylinder gasoline engine but also a diesel engine can be applied.

  A spark plug 3 is attached to the cylinder head 2 of the engine 1 for each cylinder, and an ignition coil 4 that outputs a high voltage is connected to the spark plug 3. In the cylinder head 2, an intake port 5 is provided for each cylinder, and an intake valve 7 is provided on the combustion chamber 6 side of each intake port 5. The intake valve 7 is opened and closed by a variable valve mechanism 20 which will be described later, so that each intake port 5 and the combustion chamber 6 are communicated and blocked.

  One end of an intake manifold 9 is connected to each intake port 5. An electromagnetic fuel injection valve (injection) 10 is attached to the intake manifold 9, and a fuel pipe 11 is attached to the fuel injection valve 10. The fuel pipe 11 is connected to a fuel supply device (not shown), and fuel is supplied from a fuel tank (not shown) to the fuel injection valve 10 via the fuel pipe 11.

  An electromagnetic throttle valve 12 is attached to the intake manifold 9 on the upstream side of the fuel injection valve 10, and a throttle position sensor 13 for detecting the valve opening degree of the throttle valve 12 is provided. An air flow sensor 14 for measuring the intake air amount is provided on the upstream side of the throttle valve 12.

  On the other hand, the cylinder head 2 is provided with an exhaust port 15 for each cylinder, and an exhaust valve 17 is provided on the side of the combustion chamber 6 of each exhaust port 15. The exhaust valve 17 is opened and closed by a variable valve mechanism 20 to be described later so as to communicate and block each exhaust port 15 and the combustion chamber 6.

  One end of an exhaust manifold 16 is connected to each exhaust port 15. Since such an MPI engine is a known one, details of the configuration are omitted.

  The variable valve mechanism 20 is configured to change the lift amount and the timing individually or in conjunction with each of the intake valve 7 and the exhaust valve 17. The variable valve mechanism 20 includes a variable valve lift mechanism 21 (hereinafter also referred to as a VVL mechanism) and a variable valve timing mechanism 22 (hereinafter referred to as a VVT) as mechanisms for changing the rocking amount and rocking timing of the rocker arm. (Also called a mechanism).

  The VVL mechanism 21 is a mechanism that can change the lift amount of the intake valve 7 and the exhaust valve 17 according to the control angle of the control member. For example, the VVL mechanism 21 has a function of changing the magnitude of swing (lift amount) transmitted from a cam fixed to the camshaft to a rocker arm or tappet. By changing the magnitude of the swing, the strokes of the intake valve 7 and the exhaust valve 17 are changed, and the maximum lift amount of each valve can be continuously changed. Hereinafter, the rocker shaft (an example of the control member) can change the lift amount of the intake valve 7 in accordance with the control angle, and the control angle from the reference position of the rocker shaft can be changed to the VVL control angle ( It is called a control angle in claims. The VVL control angle is a parameter corresponding to the lift amount, and the lift amount is determined on a one-to-one basis with respect to the VVL control angle. In addition, when the change amount of the control angle is positive, it indicates that the rotation is in the direction of increasing the lift amount, and when it is negative, the rotation is in the direction of decreasing the lift amount.

  The VVL mechanism 21 is configured such that the VVL control angle is arbitrarily set by a control signal from the control device 30 described later. When the VVL control angle is set, the VVL mechanism 21 rotates the swinging member with respect to the rocker shaft until the VVL control angle is reached. As a result, the intake valve 7 has a lift amount corresponding to the VVL control angle.

  FIG. 2A is a graph showing the characteristics of the lift amount of the VVL mechanism, and FIG. 2B is a graph showing the characteristics of the lift amount and the VVL control angle.

  The solid line in FIG. 2A represents the time change of the lift amount set in the VVL mechanism 21 set by the control device 30, and the dotted line represents the time change of the actual lift amount controlled by the VVL mechanism 21. A solid line indicates that the lift amount set by the control device 30 in the VVL mechanism 21 is gradually increased from a certain point in time. The broken line indicates that the actual lift amount is delayed from the lift amount (solid line) set by the control device 30. The difference between the lift amount to be set and the actual lift amount is referred to as deviation.

  Such a deviation appears for a while after the control device 30 increases the lift amount to the VVL mechanism 21, and the deviation disappears after a certain period of time. In other words, a transient state occurs until the actual lift amount matches the lift amount to be set. The calculation for more accurately estimating the intake air amount to the engine 1 in such a transient state will be described later. In addition, although the case where the lift amount is increased is illustrated in the same figure, a transient state similarly occurs when the lift amount is decreased.

  Further, as shown in FIG. 2B, the lift amount is determined on a one-to-one basis with respect to the VVL control angle. Therefore, when a specific lift amount is set according to the driving situation or the like, the VVL control angle set in the VVL mechanism 21 is specified. Hereinafter, the VVL control angle set by the control device 30 is referred to as a target VVL (deg), and the actual VVL control angle detected by the VVL mechanism 21 is referred to as an actual VVL (deg).

  The VVT mechanism 22 is a mechanism that changes the opening / closing timing (valve timing) of the intake valve 7 and the exhaust valve 17. The VVT mechanism 22 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, it is possible to continuously change (shift the timing) the rocker arm swinging timing with respect to the rotational phase of the crankshaft.

  The VVT mechanism 22 has a sensor that detects the rotational phase of the cam or camshaft, and the rotational phase detected by the sensor (hereinafter referred to as the VVT phase angle) is transmitted to the control device 30 described later. It has become.

  A vehicle equipped with the engine 1 as described above is provided with a control device 30. The control device 30 is configured as, for example, an LSI device or an embedded 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. On the in-vehicle network, 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 connected so as to communicate with each other.

  The control device 30 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 1, and the amount of air supplied to each combustion chamber 6 of the engine 1. The fuel injection amount, the ignition timing of each combustion chamber 6 and the like are controlled.

  Further, as described above, the control device 30 can set the lift amount of the intake valve 7 by setting the target VVL in the VVL mechanism 21. The VVL mechanism 21 is provided with a sensor that detects the actual VVL, and the control device 30 is configured to transmit the actual VVL by the sensor.

  Such a control device 30 calculates the intake air amount based on the data sent from the various sensors described above, and performs control so that the fuel is combusted in the combustion chamber 6 at a predetermined air-fuel ratio. Such calculation of the intake air amount may be realized by an electronic circuit (hardware) or may be realized by software. Alternatively, a part of the calculation of the intake air amount may be realized by hardware, and the other may be realized by software.

  In the present embodiment, the control device 30 includes target value setting means, control angle detection means, lift speed calculation means, lift amount estimation means, and intake air amount estimation means. Each of these means is implemented as software. The engine 1 is assumed to operate in four cycles of expansion, exhaust, intake, and compression. During the expansion stroke that is two strokes before the intake stroke, the lift amount at the completion of the intake stroke after the two strokes is estimated. A case where the intake air amount is calculated will be described. Of course, the predicted time is not limited to two strokes before, and may be during the exhaust stroke one stroke before.

  The target value setting means sets the control angle of the control member corresponding to the target value of the lift amount of the intake valve 7 from the operating state. In the present embodiment, this control angle is referred to as a target VVL. Examples of the operating state include an accelerator operation amount and a load on the engine 1.

  Such target value setting means calculates a target VVL suitable for the driving situation based on signals obtained from various sensors. The control device 30 sets the target VVL calculated by the target value setting means in the VVL mechanism 21. As a result, the VVL mechanism 21 operates so that the control angle of the control member becomes the target VVL. As a result, the intake valve 7 has a lift amount corresponding to the target VVL.

  The control angle detection means detects a control angle (actual VVL described above) that is the amount of rotation from the reference position of the control member.

  The lift speed calculation means calculates a lift speed that is a fluctuation amount per unit time of the control angle. Specifically, the lift speed is calculated as follows. First, a deviation (deg) that is a difference between the target VVL (deg) set by the target value setting means and the actual VVL (deg) detected by the control angle detection means is calculated, and the lift speed is calculated from the deviation and the speed characteristics. Is calculated. Hereinafter, the lift speed is also referred to as VVL speed, and the deviation is also referred to as VVL deviation.

  The speed characteristic is a relationship between the VVL deviation and the VVL speed. Examples of the speed characteristic include a coefficient and a function for converting the VVL deviation into the VVL speed, or a map for converting the VVL deviation into the VVL speed.

  According to such lift speed calculation means, the VVL speed can be obtained based on the VVL deviation of the intake valve 7. If there is a VVL deviation, that is, if there is a difference between the target VVL and the actual VVL, the actual VVL is considered to be in a state where the lift amount fluctuates so as to follow the target VVL. The VVL speed can be estimated from the characteristics. A detailed calculation example will be described later.

  The lift amount estimation means estimates the lift amount after the prediction period based on the VVL speed and a predetermined prediction period from the time when the VVL speed is calculated. The prediction period refers to the time from the time when the VVL speed is calculated until the time when the intake stroke of the engine 1 is completed. In the engine 1 that performs port injection, the amount of intake air that is taken into the engine 1 is determined when the intake stroke is completed. Therefore, the lift amount after the prediction period is an estimate of the lift amount when the intake stroke is completed.

  In this embodiment, since the lift amount at the completion of the intake stroke after the second stroke is estimated during the expansion stroke, the prediction period is after the second stroke. Hereinafter, the lift amount after the second stroke is also referred to as VVL after the second stroke. A detailed calculation example will be described later.

  The intake air amount estimating means estimates the intake air amount sucked into the combustion chamber 6 of the engine 1 based on the lift amount estimated by the lift amount estimating means (in this embodiment, VVL after two strokes). A specific example of the estimation of the intake air amount based on VVL after two strokes will be described later.

  3-5 is a figure which shows the processing flow in the control apparatus which concerns on this embodiment. The calculation for estimating the lift amount after two strokes and estimating the intake air amount to the engine 1 will be described in detail with reference to these drawings.

  First, as shown in FIG. 3, the control device 30 detects the actual VVL and the VVT phase angle (step S1). Specifically, the control device 30 receives the actual VVL and VVT phase angles from the VVL mechanism 21 and the VVT mechanism 22, and stores them in the storage device.

  Next, the VVL speed is estimated based on the actual VVL (step S2). The estimation of the VVL speed is performed by the processing flow shown in FIGS. Specifically, as shown in FIG. 4, the target VVL is calculated (step S10). This calculation is performed by the target value setting means, and the target VVL can be calculated by a known method based on the operation state such as the accelerator operation amount, the VVT phase angle, the load of the engine 1 and the like as described above. .

  Next, the VVL speed is calculated (steps S11 to S20). This calculation is performed by the lift speed calculation means. The lift speed calculation means calculates the VVL speed as follows.

  First, a VVL deviation is calculated (step S11). Specifically, the lift speed calculation means obtains the VVL deviation by calculating the difference between the target VVL obtained in step S10 and the actual VVL that is the control angle obtained by each control means.

  Next, the VVL speed is estimated from the VVL deviation and the speed characteristic. In this embodiment, a VVL speed conversion coefficient for converting the VVL deviation into the VVL speed is used as the speed characteristic. The VVL speed can be obtained by multiplying the VVL speed conversion coefficient by the VVL deviation.

  The VVL speed conversion coefficient can be determined by various methods such as actual measurement and simulation, and is stored in the storage device of the control device 30 in advance. The VVL speed conversion coefficient may be constant regardless of the value of the VVL deviation, or may be a value corresponding to the value of the VVL deviation. In the present embodiment, different VVL speed conversion coefficients are used depending on whether the VVL deviation is positive or zero and negative.

  Specifically, it is determined whether the VVL deviation calculated in step S11 is zero or more (step S12). When the VVL deviation is positive or zero (step S12; Yes), the VVL speed conversion coefficient corresponding to the positive or zero VVL deviation is used (step S13). When the VVL deviation is negative (step S12; No) ), The VVL speed conversion coefficient corresponding to the negative VVL deviation is used (step S14).

  Next, the VVL speed is estimated (step S15). Specifically, the VVL speed is calculated by multiplying the VVL speed conversion coefficient used in step S13 or step S14 by the VVL deviation.

  FIG. 6 is a graph showing the relationship between the VVL deviation as an input to the lift speed calculation means and the VVL speed as an output. The horizontal axis is the VVL deviation, and the vertical axis is the VVL speed. For example, in a section where the VVL deviation is 0 to a (deg), the VVL speed conversion coefficient for the VVL deviation of zero or more set in step S13 is used. This VVL speed conversion coefficient corresponds to the slope of the straight line L1. Similarly, in the interval where the VVL deviation is 0 to −b (deg), the VVL speed conversion coefficient for the negative VVL deviation set in step S14 is used. This VVL speed conversion coefficient corresponds to the slope of the straight line L2.

  Thus, although the VVL speed can be obtained from the VVL deviation and the VVL speed conversion coefficient, the actual VVL speed has an upper limit. This is because the upper limit of the lift amount of the intake valve 7, that is, the speed at which the control angle is changed by the VVL mechanism 21 is determined by the ability of the motor to rotate the control member.

  Therefore, if the speed calculated in step S15 exceeds the upper limit of such speed, the VVL speed calculated in step S15 is corrected. Specifically, it is determined whether the VVL speed obtained in step S15 is A (deg / sec) or more (step S16). This A (deg / sec) is an example of the upper limit speed of the control angle when the control angle of the control member rotates in the positive direction (the direction in which the lift amount increases) from the reference position, and is limited to this value. It is not something.

  If the estimated VVL speed is greater than or equal to A (deg / sec) (step S16; Yes), the VVL speed finally output by the lift speed calculation means is A (deg / sec) which is the upper limit speed ( Step S17). On the other hand, if the estimated VVL speed is less than A (deg / sec) (step S16; No), the VVL speed finally output by the lift speed calculation means is the VVL speed calculated in step S15.

  In the present embodiment, the VVL speed is also corrected when the VVL deviation is negative, that is, when the VVL speed obtained in step S15 is negative. Specifically, it is determined whether the estimated VVL speed is less than A (deg / sec) (step S16; No) and the estimated VVL speed is -B (deg / sec) or less (step S18). This -B (deg / sec) is an example of the upper limit speed of the control angle when the control angle of the control member rotates in the negative direction (the direction in which the lift amount decreases) from the reference position, and is limited to this value. Is not to be done.

  If the estimated VVL speed is equal to or lower than −B (deg / sec) (step S18; Yes), the VVL speed finally output by the lift speed calculation means is −B (deg / sec) which is the upper limit speed. (Step S19). On the other hand, if the estimated VVL speed is greater than -B (deg / sec) (step S18; No), the VVL speed finally output by the lift speed calculation means is the VVL speed calculated in step S15 (step S18). S20).

  In this way, the upper limit speed of the control angle by the VVL mechanism 21 and the VVL speed obtained from the VVL deviation and the VVL speed conversion coefficient are compared and corrected (steps S16 to S19), whereby the upper limit speed of the control angle is set. Therefore, it is possible to avoid estimating the VVL speed that cannot be exceeded.

  For example, as shown in FIG. 6, in the range where the VVL deviation is larger than a (deg), the VVL speed is calculated using the VVL deviation and the VVL speed conversion coefficient. As a result, the VVL speed exceeds A (deg / sec). Therefore, the VVL speed finally outputted by the lift speed calculation means is A (deg / sec) which is the upper limit speed.

  Similarly, in the range where the VVL deviation is smaller than -b (deg), the VVL speed is calculated using the VVL deviation and the VVL speed conversion coefficient. As a result, the VVL speed falls below -B. The VVL speed that is finally output is -B (deg / sec), which is the upper limit speed.

  Here, in the case where the magnitude is the same with only the sign of the VVL deviation being different, for example, in the case of + a (deg) and -b (deg), only the direction in which the control member rotates is different. The same VVL speed can also be calculated by multiplying the VVL speed conversion coefficient. However, due to the structural characteristics of the VVL mechanism 21, even if the VVL deviation is the same, the VVL speed may vary depending on the direction of rotation.

  In the present embodiment, as described above, the VVL speed is estimated using different VVL speed conversion coefficients when the VVL deviation is positive or zero and when the VVL deviation is negative. Therefore, even if the VVL deviation is the same, in the VVL mechanism 21 in which the VVL speed varies depending on the direction of rotation, the VVL speed can be estimated with higher accuracy in accordance with the direction in which the control member rotates.

  As described above, two VVL speed conversion coefficients are set according to whether the VVL deviation is positive or negative as described above, but the VVL speed conversion coefficient is not limited to this. For example, the VVL speed conversion coefficient may be a constant value regardless of the value of the VVL deviation, or the VVL deviation may be appropriately divided into a plurality of sections, and a plurality of VVL speed conversion coefficients may be set in each section.

  Based on the VVL speed estimated as described above, the lift amount after a predetermined prediction period is estimated. In this embodiment, since the lift amount at the completion of the intake stroke after the second stroke is estimated during the expansion stroke, the prediction period is after the second stroke, and the VVL after the second stroke is estimated (FIG. 3: step S3). ).

  Specifically, the lift amount estimation means estimates the VVL after the second stroke based on the VVL speed obtained by the lift speed calculation means and the time from the time when the VVL speed is calculated to the time after the second stroke. That is, the VVL after the second stroke is obtained by multiplying the VVL speed by the time until the second stroke. The VVL after the second stroke is the amount of change (deg) of the control angle from the time when the VVL speed is calculated to the time after the second stroke, and is therefore the sum of the actual VVL (deg) that is the control angle when the VVL speed is calculated. And the lift amount corresponding to the sum can be obtained as VVL (mm) after two strokes from the correspondence as shown in FIG.

  Next, the intake air amount estimation means estimates the intake air amount Ec sucked into the combustion chamber 6 of the engine 1 (FIG. 3: Steps S4 to S6). In the present embodiment, the intake air amount (Ec) calculated according to the driving situation is set as the target Ec, and the target Ec corrected by the maximum intake amount after two strokes is set as Ec for fuel calculation.

  First, the maximum intake air amount after two strokes is estimated from VVL after two strokes (FIG. 3: step S4). The maximum intake air amount is a maximum value of the intake air amount sucked into the combustion chamber 6 of the engine 1. Based on the VVL after the second stroke obtained in step S3, the configuration of the engine 1, the shape of the intake valve 7, etc., the maximum intake amount after the second stroke can be calculated by a known method.

  Next, the target Ec is calculated (FIG. 3: step S5). Here, the calculation of the target Ec and the fuel calculation Ec in the present invention will be described in comparison with the prior art.

  FIG. 7A is a graph showing time-series changes in the intake air amount, the opening degree of the throttle valve 12, the lift amount of the intake valve 7 and the pressure in the intake manifold 9 in the prior art, and FIG. 4 is a graph showing time-series changes in the intake air amount, the opening degree of the throttle valve 12, the lift amount of the intake valve 7 and the pressure in the intake manifold 9 in the present invention. In either case, the horizontal axis represents time, and the vertical axis represents the size of each parameter.

  As shown in FIG. 7A, in the prior art, the target Ec is the target VVL set according to the driving situation, the opening of the throttle valve 12 set according to the driving situation, and the intake manifold 9 It is calculated by a known method using the pressure as a parameter. Then, by correcting the target Ec considering that the opening of the throttle valve 12 is delayed from the target value, it is possible to obtain the corrected Ec that is the corrected intake air amount.

  In such a conventional technique, the target Ec is not calculated in consideration of the fact that the lift amount of the intake valve 7 becomes slower than the target value. Therefore, the correction Ec obtained based on this and the intake air amount actually sucked into the engine 1 (hereinafter referred to as the actual Ec) are the dotted line X obtained by translating the correction Ec by two strokes, and the actual Ec. As shown in the shaded portion S between the two, a deviation occurs.

  On the other hand, in the calculation of the target Ec in the present invention (FIG. 3: Step S5), as shown in FIG. The degree and the pressure in the intake manifold 9 are parameters, and are calculated by a known method. That is, it is considered that the lift amount of the intake valve 7 operates with a delay from the target value by using the VVL after the second stroke. In the example of the figure, the target Ec of the present invention is set to be smaller by the shaded portion T than the target Ec of the prior art. Then, the fuel calculation Ec is obtained by correcting the target Ec calculated using the VVL after two strokes (FIG. 3: step S6).

  Thus, in the present invention, the target Ec is calculated in consideration of the fact that the lift amount of the intake valve 7 becomes slower than the target value. Therefore, the difference between the Ec for fuel calculation obtained based on this and the actual Ec can be reduced. That is, when the fuel calculation Ec is moved in parallel by two strokes, it substantially matches the actual Ec. As described above, the correction Ec according to the prior art has deviated from the actual Ec as in the shaded portion S, but in the present invention, the deviation from the actual Ec represented by such a shaded portion S is reduced. can do.

  Thereafter, although not particularly illustrated, the control device 30 calculates the air-fuel ratio according to the operating condition by a known method using parameters such as the VVT phase angle and the fuel calculation Ec calculated by the intake air amount estimation means, Fuel is supplied to the combustion chamber of the engine 1 at the air-fuel ratio.

  As described above, according to the control device 30 according to the present invention, the VVL mechanism 21 that cannot directly obtain the VVL speed can obtain the VVL speed based on the VVL deviation. By obtaining the VVL speed in this way, it becomes possible to estimate the VVL after the second stroke which is the lift amount of the intake valve 7 after the second stroke. Since the fuel calculation Ec is estimated based on the VVL after the second stroke, the fuel calculation Ec takes into account that the intake valve 7 operates later than the target VVL. Deviation from Ec can be reduced.

  Thus, according to the control device 30 according to the present invention, the fuel calculation Ec is estimated with higher accuracy as the amount of air supplied to the engine 1 in a transient state when the lift amount of the intake valve 7 is changed. be able to. Since the fuel can be burned at the air-fuel ratio adjusted based on the fuel calculation Ec, the engine 1 can be operated more efficiently.

<Embodiment 2>
In the control device 30 according to the first embodiment, different speed characteristics set in each case where the VVL deviation is positive or negative are used as the speed characteristics (VVL speed conversion coefficient) for obtaining the VVL speed from the VVL deviation. It is not limited to. For example, different speed characteristics may be set depending on whether the VVL deviation is increasing or decreasing.

  The control device according to the present embodiment has the same configuration as that of the control device according to the first embodiment except for the lift speed calculating means, and the processing flow is the same as that of the first embodiment with respect to step S1, step S3 to step S6. Since it is the same as the control apparatus which concerns, the overlapping description is abbreviate | omitted.

  FIG. 8 is a graph showing speed characteristics used based on the VVL deviation. In FIGS. 8A and 8B, the horizontal axis represents time, and the vertical axis represents the control angle (denoted as VVL). FIG. 8A shows a temporal change between the target VVL and the actual VVL in a transient state where the actual VVL is smaller than the target VVL, that is, a transient state where the VVL is increasing, and FIG. It shows the change over time between the target VVL and the actual VVL in a transient state larger than VVL, that is, in a transient state where VVL is decreasing.

  In FIG. 8C and FIG. 8D, the horizontal axis is time, and the vertical axis is VVL deviation. FIG. 8 (c) corresponds to FIG. 8 (a) and shows the change over time in the VVL deviation in the transient state where VVL increases, and FIG. 8 (d) corresponds to FIG. 8 (b) and VVL decreases. It shows the change over time of the VVL deviation in the transient state.

  FIG. 8E and FIG. 8F are velocity maps that are examples of velocity characteristics. The horizontal axis is the VVL deviation, and the vertical axis is the VVL speed. This speed map is used to obtain the VVL speed as an output from the VVL deviation as an input of the lift speed calculation means. FIG. 8E is a speed map used when the VVL deviation is decreasing (hereinafter referred to as a VVL deviation decreasing speed map), and FIG. 8F is used when the VVL deviation is increasing. Is a speed map (hereinafter referred to as a VVL deviation increasing speed map).

  The lift speed calculation means uses a VVL deviation decreasing speed map and a VVL deviation increasing speed map, which are different speed characteristics depending on whether the VVL deviation is increasing or decreasing.

  As shown in FIG. 8A, in the transient state where the actual VVL increases so as to follow the target VVL, as shown in FIG. 8C, the VVL deviation is always positive, but the magnitude is It has fluctuated. Specifically, the VVL deviation increases in the first half, maintains a constant value for a while, and decreases in the second half.

  Also, as shown in FIG. 8B, in the transient state where the actual VVL decreases so as to follow the target VVL, the VVL deviation is always negative as shown in FIG. That fluctuates. Specifically, the VVL deviation decreases in the first half, maintains a constant value for a while, and increases in the second half.

  The difference between the VVL deviation at a certain time point and the VVL deviation at the previous time point is defined as a change rate of the VVL deviation. For example, the VVL deviation is stored for each calculation cycle in which a series of calculations from step S1 to step S6 shown in FIG. 3 is performed, and in the next calculation cycle, the newly calculated VVL deviation and the previous cycle are used. The change rate of the VVL deviation can be calculated from the difference from the stored VVL deviation.

  When the VVL deviation is positive and the change rate of the VVL deviation increases (section T1 in FIG. 8C), the VVL deviation increase in FIG. 8F is obtained as a speed map for obtaining the VVL speed from the VVL deviation. Refer to the right half of the hourly speed map (VVL deviation is zero or more).

  When the VVL deviation is positive and the change rate of the VVL deviation is decreasing (section T2 in FIG. 8C), the VVL deviation reduction in FIG. 8E is obtained as a speed map for obtaining the VVL speed from the VVL deviation. Refer to the right half of the hourly speed map (VVL deviation is zero or more).

  When the VVL deviation is negative and the change rate of the VVL deviation is decreasing (section T3 in FIG. 8D), the VVL deviation reduction in FIG. 8E is obtained as a speed map for obtaining the VVL speed from the VVL deviation. Refer to the left half of the hourly speed map (VVL deviation is less than zero).

  When the VVL deviation is negative and the change rate of the VVL deviation is increasing (section T4 in FIG. 8D), the VVL deviation increase in FIG. 8F is obtained as a speed map for obtaining the VVL speed from the VVL deviation. Refer to the left half of the hourly speed map (VVL deviation is less than zero).

  If the speed map to be referred to is determined in this way, the VVL speed corresponding to the calculated VVL deviation can be obtained. As in the first embodiment, when the VVL speed corresponding to the VVL deviation exceeds the upper limit value, the upper limit value is set as the VVL speed.

  A process for estimating the VVL speed from the speed map described above will be described. The control device 30 according to the present embodiment executes a series of processes from step S1 to step S6 in the same manner as in the first embodiment at every predetermined calculation cycle. The estimation of the VVL speed in step S2 is performed according to the processing flow shown in FIG.

  FIG. 9 is a diagram illustrating a processing flow in the control device according to the present embodiment. First, the target VVL is calculated (step S21). This calculation is performed by the target value setting means, and the target VVL can be calculated by a known method based on the operation state such as the accelerator operation amount, the VVT phase angle, the load of the engine 1 and the like as described above. .

  Next, the VVL deviation is calculated (step S22). Specifically, the lift speed calculation means obtains the VVL deviation by calculating the difference between the target VVL obtained in step S10 and the actual VVL that is the control angle obtained by each control means.

  Next, the change rate of the VVL deviation is calculated (step S23). Specifically, the lift speed calculation means obtains the change rate of the VVL deviation by calculating the difference between the current VVL deviation and the previous VVL deviation. The current VVL deviation is the VVL deviation obtained by calculation in step S22 in the current calculation cycle, and the previous VVL deviation is the VVL deviation obtained in step S22 in the previous calculation cycle. Each time the VVL deviation is calculated, the lift speed calculation means stores the VVL deviation so that it can be referred to in the next calculation cycle.

  The change rate of the VVL deviation obtained in this way represents how much the VVL deviation has changed between the current and previous calculation cycles. It is determined whether such a change rate of the VVL deviation is α or less (step S24). α is a threshold value for determining that the VVL deviation is increasing. Such α is stored in the storage device of the control device 30 in advance.

  If the change rate of the VVL deviation is larger than α (step S24; No), it is determined that the VVL deviation is increasing, and the VVL deviation increasing speed map is referred to (step S25).

  Then, the VVL speed is estimated from the VVL deviation increasing speed map (step S26). When the rate of change of the VVL deviation increases and the VVL deviation is positive (section T1 in FIG. 8C), the VVL deviation is referred to by referring to the right half of the VVL deviation increasing speed map shown in FIG. VVL speed can be obtained from

  Similarly, when the change rate of the VVL deviation increases and the VVL deviation is negative (section T4 in FIG. 8 (d)), refer to the left half of the VVL deviation increasing speed map shown in FIG. 8 (f). The VVL speed can be obtained from the VVL deviation.

  On the other hand, when the change rate of the VVL deviation is α or less (step S24; Yes), it is determined whether the change rate of the VVL deviation is β or less (step S27). β is a threshold value for determining that the VVL deviation is decreasing. Such β is stored in the storage device of the control device 30 in advance.

  When the change rate of the VVL deviation is equal to or less than β (step S27; Yes), it is determined that the VVL deviation is decreasing, and the VVL deviation decreasing speed map is referred to (step S28).

  Then, the VVL speed is estimated from the VVL deviation decreasing speed map (step S29). When the change rate of the VVL deviation decreases and the VVL deviation is positive (section T2 in FIG. 8C), the VVL deviation is referred to by referring to the right half of the VVL deviation decreasing speed map shown in FIG. VVL speed can be obtained from

  Similarly, when the change rate of the VVL deviation decreases and the VVL deviation is negative (section T3 in FIG. 8D), refer to the left half of the VVL deviation decreasing speed map shown in FIG. The VVL speed can be obtained from the VVL deviation.

  If the VVL deviation rate of change is larger than β (step S27; No), that is, if β <VVL deviation rate of change ≦ α, whether or not the VVL deviation rate of change in the previous calculation cycle has decreased. Determination is made (step S30). In each calculation cycle, the change rate of the VVL deviation is stored in the storage device so that it can be referred to in the next and subsequent calculation cycles.

  After calculating the VVL speed in this way, the VVL after the second stroke is estimated as in the first embodiment (FIG. 3: step S3), and the maximum intake air amount after the second stroke is estimated (FIG. 3: step S4). Ec is calculated (FIG. 3: step S5), and Ec for fuel calculation is calculated (FIG. 3: step S6).

  As described above, due to the structural characteristics of the VVL mechanism 21, even when the VVL deviation is the same, the VVL speed corresponding to the VVL deviation depends on whether the VVL deviation increases or decreases. May be different (FIGS. 8E and 8F).

  In the control device 30 according to the present embodiment, as a speed characteristic for obtaining the VVL speed from the VVL deviation, as an example of a speed characteristic that differs depending on whether the VVL deviation is increasing or decreasing, a VVL deviation increasing speed map and A VVL deviation reduction speed map was used. That is, even if the VVL deviation is the same, in the VVL mechanism 21 in which the VVL speed is different depending on whether the VVL deviation is increasing or decreasing, a speed suitable for each increase or decrease of the VVL deviation. The map can be used to estimate the VVL velocity with higher accuracy.

  In the present embodiment, two different speed maps are set for each of the case where the VVL deviation is increasing and the case where the VVL deviation is decreasing. However, the present invention is not limited to such a mode. Three or more speed maps may be set. For example, assuming that the change rate of the VVL deviation is X, three different speed maps may be set for each of cases where X is less than β, more than β and less than α, and greater than α.

<Embodiment 3>
FIG. 10 is a diagram illustrating a time difference from when the target VVL is set until when the lift amount of the intake valve actually starts to move in the VVL mechanism.

  When the target VVL is set by the control device 30, the VVL mechanism 21 rotates the control member until, for example, the motor is started and reaches the target VVL. In such a VVL mechanism 21, for example, if the calculation cycle is 10 msec, the VVL speed is estimated every 10 msec. When the target VVL is calculated in the current calculation cycle (FIG. 4: step S10 and FIG. 9: step S21), the motor of the VVL mechanism 21 is started so that the target VVL is reached.

  At this time, there is a delay time from when the target VVL is set until the motor actually starts operating. For example, if the delay time in the current calculation cycle is 20 msec, strictly speaking, the VVL speed estimated in the current calculation cycle (FIG. 4: step S15 or FIG. 9: step S26, step S29) is 20 msec later. This is an estimation of the speed of the VVL deviation.

  The control device according to the present embodiment estimates the lift amount by calculating this delay time. The control device according to the present embodiment has the same configuration as the control device according to the first embodiment except for the lift speed calculation unit and the lift amount estimation unit, and the processing flow includes steps S1, S3 to S6. Since it is the same as that of the control device according to the first embodiment, overlapping description is omitted.

  The lift speed calculation means of the control device according to the present embodiment calculates the VVL speed for each calculation cycle (predetermined cycle in claims) and stores the VVL speed calculated for each calculation cycle.

  In this embodiment, since the calculation cycle is 10 msec, the VVL speed is stored in the storage device every 10 msec. At least the number of VVL speeds to be referred to is stored as in the previous time and the last time described later.

  The lift amount estimation means calculates the lift amount using the lift speed calculated in the previous calculation period during the delay time until the actual operation starts so that the lift amount of the intake valve 7 becomes the target VVL. presume.

As shown in FIG. 10, the VVL speeds estimated in the previous calculation cycle (−20 msec), the previous time (−10 msec), and the current calculation cycle are V ₋₂ , V ₋₁ , and V ₀ , respectively.

The prediction period is from the time when the VVL speed is calculated until after the completion of the intake stroke. In this embodiment, the prediction period is from the expansion stroke before the two strokes to the completion of the intake stroke, so the prediction period is also referred to as a two-stroke cycle. . When the two-stroke cycle is longer than the delay time (for example, 25 msec), the lift amount after the prediction period can be calculated as follows using V ₋₂ , V ₋₁ , and V ₀ . The calculation cycle is 10 msec.

Lift amount = V ₋₂ × calculation cycle + V ₋₁ × calculation cycle
+ V ₀ × (forecast period−2 × calculation cycle) (Formula 1)

Similarly, although not particularly shown, when the two-stroke cycle is shorter than the delay time and longer than one calculation cycle (for example, 10 to 20 msec), the lift amount after the prediction period is V ₋₂ and V ₋₁ . And can be calculated as follows:

Lift amount = V ₋₂ × calculation cycle + V ₋₁ × (forecast period−calculation cycle) (Formula 2)

Furthermore, when the two-stroke cycle is shorter than the delay time and shorter than one calculation cycle (for example, less than 10 msec), the lift amount after the prediction period can be calculated as follows using V- _2. .

Lift amount = V ₋₂ × prediction period (Formula 3)

  Hereinafter, the lift amount after the prediction period is referred to as the estimated VVL operation amount during the two strokes, and the processing in the control device will be described with reference to FIG. FIG. 11 is a diagram illustrating a processing flow in the control device according to the present embodiment.

  After estimating the VVL speed (FIG. 5: Step S17, S19 or S20, FIG. 9: Step S26 or S29), the control device 30 according to the present embodiment determines whether the two-stroke cycle is 20 msec or less. (Step S31).

  When the two-stroke cycle is longer than 20 msec (step S31; No), the VVL operation amount between the two estimated strokes is calculated by the above equation 1 (step S32). If the two-stroke cycle is 20 msec or less (step S31; Yes), it is determined whether the two-stroke cycle is 10 msec or less (step S33).

  When the two-stroke cycle is longer than 10 msec (step S33; No), the VVL operation amount between the two estimated strokes is calculated by the above equation 2 (step S34). When the two-stroke cycle is 10 msec or less (step S33; Yes), the VVL operation amount between the estimated two strokes is calculated by the above equation 3 (step S35).

  The estimated VVL operation amount between the two strokes obtained in this way is the amount of change (deg) of the control angle from the time when the VVL speed is calculated to the time after the second stroke, and is the control angle at the time when the VVL speed is calculated. By calculating the sum with a certain actual VVL (deg), a control angle after the second stroke (estimated VVL control angle after the second stroke) can be obtained (step S36).

  Thereafter, although not shown in particular, the lift amount corresponding to the VVL control angle estimated after the two strokes can be obtained as the VVL (mm) after the two strokes from the correspondence shown in FIG. 2B (FIG. 3: Step S3). ). As in the first embodiment, the maximum intake air amount after two strokes is estimated (FIG. 3: step S4), the target Ec is calculated (FIG. 3: step S5), and the fuel calculation Ec is calculated (FIG. 3: Step S6).

  As described above, the control device 30 according to the present embodiment calculates this delay time in the VVL mechanism 21 that has a delay time from when the target VVL is set until the motor actually starts operating. To estimate the VVL speed. Thereby, even when the VVL mechanism 21 has a delay time, the VVL speed can be estimated with higher accuracy.

  The present invention can be used in the industrial field of automobiles.

1 Engine 5 Intake Port 6 Combustion Chamber 7 Intake Valve 20 Variable Valve Mechanism 21 Variable Valve Lift Mechanism (VVL Mechanism)
22 Variable valve timing mechanism (VVT mechanism)
30 Control device

Claims (4)

A control device for an internal combustion engine comprising a variable valve mechanism capable of changing a lift amount of an intake valve according to a control angle of a control member,
Target value setting means for setting a control angle corresponding to the target value of the lift amount of the intake valve from the operating state of the internal combustion engine;
Control angle detection means for detecting a control angle from a reference position of the control member;
Lift speed calculating means for calculating a lift speed that is a fluctuation amount per unit time of the control angle;
Lift amount estimation means for estimating a lift amount after the prediction period based on the lift speed and a predetermined prediction period from the time when the lift speed is calculated;
Intake air amount estimating means for estimating the intake air amount sucked into the combustion chamber of the internal combustion engine based on the lift amount estimated by the lift amount estimating means;
The lift speed calculation means calculates a deviation which is a difference between the control angle set by the target value setting means and the control angle detected by the control angle detection means, and the relationship between the deviation and the lift speed is calculated. A control device for an internal combustion engine, characterized in that the lift speed is calculated from a speed characteristic that is expressed. The control apparatus for an internal combustion engine according to claim 1,
The control apparatus for an internal combustion engine, wherein the lift speed calculation means uses different speed characteristics depending on whether the deviation is positive or negative. In the control device for an internal combustion engine according to claim 1 or 2,
The control device for an internal combustion engine, wherein the lift speed calculation means uses different speed characteristics depending on whether the deviation is increasing or decreasing. In the control device for an internal combustion engine according to any one of claims 1 to 3,
The lift speed calculating means calculates the lift speed for each predetermined period and stores the lift speed calculated for each period,
The lift amount estimation means uses the lift speed calculated in the previous cycle during the delay time until the actual operation starts so that the lift amount of the intake valve becomes the target value. A control device for an internal combustion engine characterized by estimating an amount.