JP2010031699A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, not impairing drivability of a driver on condition that stable control is performed while avoiding the operating condition of a direct-injection engine by suppression of intake air volume. <P>SOLUTION: This control device for a cylinder injection type internal combustion engine is provided with an accelerator opening detection means detecting an accelerator opening, a throttle valve adjusting the intake air volume, an intake air volume detection means detecting the adjusted intake air volume, and a temperature detection means detecting the intake air temperature of the internal combustion engine. The control device includes an air density calculation means calculating density of air sucked based on at least intake air temperature, a maximum target intake air volume calculation means calculating the maximum target intake air volume based on the air density, an accelerator opening ratio calculation means calculating an accelerator opening ratio with respect to the accelerator opening during a full open, a means calculating a target intake air volume by multiplying the maximum target intake air volume by the accelerator opening ratio, and a throttle valve control means controlling the throttle valve so that the intake air volume is set to the target intake air volume. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an in-cylinder injection type internal combustion engine (engine) that directly injects fuel into the cylinder, and more particularly to an internal combustion engine that can control the internal combustion engine suitably even in a low temperature environment. The present invention relates to a control device.

  Conventionally, an in-cylinder injection gasoline engine (hereinafter referred to as a direct injection engine) that directly injects fuel such as gasoline into a cylinder is a known engine. In this direct injection engine, design values of respective parts constituting the direct injection engine are determined based on required values presented from the engine specifications and the environment in which the direct injection engine is used. In order to ensure that the required value is satisfied, it is desirable that this design value is larger, but in reality, there are restrictions on manufacturing or structure, and an upper limit value and a lower limit value are determined.

  For example, fuel injection valves for the purpose of injecting fuel and air flow meters (hereinafter referred to as air flow sensors) for the purpose of measuring the amount of intake air have required maximum and minimum flow rates as required values. Exists. The best mode is to give these devices or the components constituting them any characteristic that satisfies the requirements of both the maximum flow rate and the minimum flow rate. It is not possible to satisfy both required values. In particular, these devices have a characteristic that when the maximum flow rate as a restriction is increased, the minimum flow rate increases, and conversely, when the minimum flow rate is reduced, the maximum flow rate decreases. Thus, there is a so-called trade-off relationship between the maximum flow rate and the minimum flow rate. Similarly, a high-pressure fuel pump has a trade-off relationship between friction and fuel discharge amount.

  From such a background, the design value of the parts constituting the engine is provided with a maximum value including an air flow sensor (the air flow sensor is an air amount, the fuel injection valve or the high-pressure fuel pump is a fuel flow rate) including a stable operation guarantee. Further, it is known that the fuel flow rate of not only a direct injection engine but also a general internal combustion engine is determined by the intake air amount and the air-fuel ratio. In other words, it can be said that these parts have a design maximum intake air amount (hereinafter referred to as a maximum intake air amount) including the warranty of the parts, and the design upper limit value is a certain amount from the maximum intake air amount. It is a value with a margin.

  However, as a future trend, it is expected that the output of the direct injection engine will be further increased, and a margin existing between the maximum intake air amount and the design maximum value is reduced. For this reason, there may be a use condition exceeding the maximum intake air amount in an environment such as a low temperature where the air density increases, and there is a concern that it is difficult to guarantee stable operation of the components constituting the direct injection engine.

In view of such a point, for example, the maximum intake air amount is corrected in accordance with the air density sucked into the internal combustion engine, and the intake air amount is manipulated so as not to exceed the maximum intake air amount. A control device has been proposed (see, for example, Patent Document 1). According to the control device for the internal combustion engine, the maximum intake air amount is corrected according to the air density. Therefore, even if the density of the intake air is high at a low temperature, the intake air corresponding to the air density is high. A quantity of air can be drawn into the internal combustion engine.
JP-A-10-47114

  However, when control is performed by the control device described in Patent Document 1, it is possible to suppress the maximum intake air amount according to the intake air density. Even if the engine is continuously stepped on, the intake air amount that exceeds the target intake air amount cannot be expected, so that the engine output reaches a peak, resulting in a stall feeling associated with it, and a drivability problem is expected to remain.

  The present invention is based on such an idea, and is based on the premise that stable control that does not exceed the maximum intake air amount is achieved while avoiding the operating conditions of the direct injection engine by suppressing the intake air amount. It is to provide a control device for an internal combustion engine that does not impair the drivability of a person.

  In order to solve the above-described problems, an internal combustion engine control apparatus according to the present invention includes an accelerator opening detecting means for detecting an accelerator opening, a throttle valve for adjusting an intake air amount, and an intake air for detecting the intake air amount. A control device for an in-cylinder injection type internal combustion engine, comprising a quantity detection means and a temperature detection means for detecting an intake air temperature of the internal combustion engine, wherein the control device is inhaled based on at least the intake air temperature Air density calculating means for calculating the air density, maximum target intake air amount calculating means for calculating the maximum target intake air amount based on the air density, and calculating the ratio of the accelerator opening to the accelerator opening when fully opened Means for calculating the accelerator opening ratio, means for calculating the target intake air amount by multiplying the maximum target intake air amount by the accelerator opening ratio, and the intake air amount becomes the target intake air amount A throttle valve control means for controlling the urchin said throttle valve, characterized in that it comprises a.

  In the control apparatus for an internal combustion engine according to the present invention, the throttle valve control means controls the throttle valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully open. Is more preferable.

  The control apparatus for an internal combustion engine according to the present invention further includes a lift amount adjusting means for adjusting a lift amount of the intake valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully opened. More preferably.

  The control device for an internal combustion engine according to the present invention adjusts the opening / closing timing of the intake valve and the exhaust valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully opened. More preferably, means are further provided.

  The internal combustion engine of the control device for an internal combustion engine according to the present invention more preferably includes a supercharging device that forcibly supercharges at least the intake air amount.

  As another aspect, the control apparatus for an internal combustion engine according to the present invention includes an accelerator opening detecting means for detecting an accelerator opening, a throttle valve for adjusting an intake air amount, and a throttle opening for detecting the throttle opening of the throttle valve. A control device for a direct injection internal combustion engine comprising a degree detection sensor and a temperature detection means for detecting an intake air temperature of the internal combustion engine, wherein the control device is inhaled based on at least the intake air temperature Air density calculating means for calculating the air density, maximum target throttle opening calculating means for calculating the maximum target throttle opening based on the air density, and calculating the ratio of the accelerator opening to the accelerator opening when fully opened An accelerator opening ratio calculating means for calculating the target throttle opening by multiplying the maximum target throttle opening by the accelerator opening ratio And stage, the throttle opening degree is characterized by comprising a throttle valve control means for controlling said throttle valve so that the target throttle opening.

  In the control apparatus for an internal combustion engine according to the present invention, the throttle valve control means controls the throttle valve so that the throttle opening converges to the maximum target throttle opening when the accelerator opening is fully open. Is more preferable.

  According to the present invention, in an environment where the air density increases, the engine output tends to increase as the amount of intake air increases. By suppressing this increase in output, a direct-injection engine with high output can be achieved. Not only can the components (particularly fuel injection valves, air flow meters, and high-pressure fuel pumps) be configured to operate stably, but also control the engine while avoiding the operating conditions of the direct injection engine by controlling the intake air volume. The driver's drivability will not be impaired on the assumption that

  Below, with reference to drawings, the control device of the internal-combustion engine concerning the present invention is explained based on two embodiments.

  FIG. 1 is a schematic conceptual diagram of an internal combustion engine controlled by a control device according to the first embodiment.

  As shown in FIG. 1, the present invention is a multi-cylinder in-cylinder injection engine 1, and FIG. 1 is a view for explaining one cylinder. FIG. 2 is a block diagram showing the internal configuration of the control device for controlling the engine shown in FIG. 1 and its input / output signals.

  In the engine (internal combustion engine) 1, air in the atmosphere is sucked into the combustion chamber 111 from an intake passage 102 via an air filter (not shown). An air flow sensor (intake air amount detection means) 103 for measuring the intake air amount and an electrically controlled throttle valve (electrically controlled throttle) 104 for adjusting the intake air amount are provided in the intake path 102.

  These devices are connected to a control unit (control device) 20 as shown in FIG. 2, and the control unit 20 calculates the intake air amount from the information obtained from the air flow sensor 103, Based on this, the position of the electric throttle 104 is controlled.

  On the other hand, in the engine 1, the fuel sent to the high-pressure fuel pump 119 by a lift pump (not shown) that pumps up from a fuel tank (not shown) is boosted by the high-pressure fuel pump 119 and then passed through the gallery 120. The fuel injection valve 122 is directly injected into the combustion chamber 111.

  These devices are also connected to the control unit 20 as shown in FIG. 2, and the control unit 20 is configured to set the above-described intake air amount and fuel ratio (hereinafter referred to as air-fuel ratio) and the air flow sensor 103. An appropriate fuel injection amount is determined from the intake air amount obtained from the above. In addition, the gallery 120 is provided with a fuel pressure sensor 121 for measuring the fuel pressure in the gallery, and the high pressure fuel pump is controlled by the control unit 20 so as to obtain an appropriate fuel pressure.

  In this manner, the air sucked into the combustion chamber 111 and the fuel injected from the fuel injection valve 122 become an air-fuel mixture that is easily combusted in the combustion chamber 111. The control unit 20 calculates an appropriate ignition timing and outputs an ignition signal to the ignition coil 123.

  In the ignition coil 123, there are a primary coil and a secondary coil with different numbers of turns of the copper wire, and a voltage (current) is charged into and cut off from the primary coil based on the ignition signal. When a voltage is applied to the primary coil, a voltage corresponding to the turn ratio of the copper wire is also generated in the secondary coil by electromagnetic induction. A high voltage generated in the secondary coil is applied to the spark plug 124 to ignite the air-fuel mixture.

  After the air-fuel mixture burns in the combustion chamber 111, it is discharged into the exhaust passage 125 as exhaust gas. Further, the exhaust path 125 is provided with a catalyst 127, and the exhaust gas purified by the catalyst 127 is again opened to the atmosphere.

  Since the catalyst 127 has an air-fuel ratio that can bring out the purification capacity to the maximum source, the control unit 20 determines the air-fuel ratio target based on the air-fuel ratio information from the air-fuel ratio sensor 126 arranged upstream of the catalyst 127. So-called feedback control is performed between the values.

  Due to the pressure in the combustion chamber 111 generated by the combustion in the combustion chamber 111, the piston 112 exerts a downward force, which is transmitted to the crankshaft (not shown) via the connecting rod 113 and converted into rotational motion. Is done. This is the output of the engine 1.

  The crankshaft (not shown) is provided with a flywheel 114 so that the rotational motion is smoothly performed, and the crank angle sensor 115 detects an edge provided on the outer peripheral portion of the flywheel 114. On the other hand, the rotational force of the crankshaft (not shown) is transmitted to the camshafts 116a and 116b on the upper part of the engine body 101 by a belt or a chain. Thus, the camshafts 116a and 116b rotate in synchronization with the crankshaft (not shown). The camshafts 116a and 116b are designed to rotate once for two rotations of the crankshaft.

  The camshafts 116a and 116b have different positions and numbers depending on the layout of the engine, but in this figure, the camshafts 116a and 116b are provided at the upper part of the engine body 101, and so-called camshafts 116a and 116b are provided for intake and exhaust. A double overhead cam type (DOHC) direct injection engine is shown. The movement characteristics of the intake valve 109 or the exhaust valve 110 are determined based on the cam shapes on the camshafts 116a and 116b. As with the crankshaft, the control unit detects the rotation of the camshaft by cam angle sensors 117a and 117b.

  Although not shown in this figure, the variable valve that can change the movement characteristic intermittently or continuously by a motor or the like without the movement characteristic of the intake valve 109 or the exhaust valve 110 being dependent on the cam shape. The present invention is effective. Further, a turbocharger, a crankshaft (not shown), and a dedicated shaft are used as a device (a supercharging device for forcibly supercharging the intake air amount) using a pressure at which exhaust gas is pushed out from the combustion chamber 111 to the exhaust passage 125. It is also effective for a direct-injection engine having at least one device such as a supercharger using a crankshaft rotational force.

  Next, details of the control unit 20 will be described as shown in FIG. The main part includes a CPU 203, an EP-ROM 202, a RAM 204, an I / O LSI 205 including an A / D converter, and the like. From the crankshaft rotation angle detection sensor (crank angle sensor) 115, cam angle sensors 117a, 117b, and the like, the control unit 20 calculates the engine speed, the ignition timing, and the like.

  The control unit 20 outputs a control signal from the position information of an accelerator opening sensor (accelerator opening detecting means) 206 that detects the opening of an accelerator pedal (not shown) operated by the driver, and the electric throttle 104 Control. Then, the control unit 20 grasps the position of the electric throttle 104 by a throttle opening sensor 105 that detects the opening of the electric throttle 104, and based on the detection signal of the throttle opening sensor 105, the electric throttle 104 The degree of opening can be corrected. Thereby, precise control of the electric control throttle 104 becomes possible.

  Further, the control unit 20 obtains the current intake air amount described above by the air flow sensor 103 and then calculates the total appropriate fuel injection time together with the engine speed and sends a pulse signal to the fuel injection valve 122. send. The fuel injection valve 122 performs fuel injection by opening and closing the needle in the fuel injection valve 122 based on the pulse signal. For the ignition system, the control unit 20 outputs an ignition signal to the ignition coil 123 in accordance with an optimal ignition timing that varies depending on engine operating conditions and the like. By this ignition signal, a high voltage is applied from the ignition coil 123 to the ignition plug 124, and the fuel (air mixture) is ignited by the ignition plug 124. The temperature sensor (temperature detection means) is a device for detecting the intake air temperature or the outside air temperature of the internal combustion engine, and is for calculating the density of the intake air, which will be described later. Similarly, the pressure sensor is a device for detecting an external pressure (for example, atmospheric pressure), and may be used to calculate the density of inhaled air described later.

  FIG. 3 is a graph showing the relationship between the air density change rate and the air temperature, where the vertical axis indicates the increase / decrease ratio of the air density and the horizontal axis indicates the air temperature. As shown in FIG. 3, it can be seen from the air density curve that the air density increases as the temperature decreases. Although not shown in the figure, the air density also changes depending on conditions such as the external air pressure (the air density increases as the atmospheric pressure increases).

  FIG. 4 is a diagram for explaining an operating state of the direct injection engine due to an air density accompanying a change in temperature. For example, in the section A, when the accelerator pedal is stepped on by the driver's operation, the control unit 20 obtains the position information of the accelerator pedal based on the accelerator opening signal from the accelerator opening sensor 206.

  Based on the position information of the accelerator pedal (accelerator opening signal), the control unit 20 controls the opening (throttle opening) of the electric throttle 104 in the opening direction. Thereby, the amount of intake air increases.

  However, as shown in FIG. 3, the increase characteristic changes depending on the temperature (here, the intake air temperature) due to the nature of the air density. In FIG. 4, the intake air amount at the standard temperature (25 ° C.) is indicated by a broken line, and the intake air amount at the low temperature is indicated by a solid line. Compared with the temperature (broken line), the slope with respect to the increase in the section A becomes steeper, and the intake air amount described above also increases in the section B when the throttle opening is fully open. In this characteristic, as the intake air temperature is lower, the increasing slope becomes steeper and the intake air amount described above when fully opened increases. In view of such points, the present embodiment is configured as follows.

  First, the control that is the premise of the present embodiment is shown below. FIG. 5 is a control flowchart as a premise of the present embodiment, and FIG. 6 shows a timing chart when the control of FIG. 5 is performed. First, in S501, the control unit 20 calculates the maximum target intake air amount. This maximum target intake air amount is the maximum value of the target intake air amount described later, and is calculated by multiplying the standard maximum target intake air amount required in the standard state (for example, 25 ° C.) by the air density. Specifically, the outside air temperature and the intake air temperature are detected by a temperature sensor that measures the outside air temperature, and the air density corresponding to the detected temperature is calculated using, for example, a graph or table as shown in FIG. . The maximum target intake air amount is calculated from the air density and the standard maximum target intake air amount detected in the standard state, and the process proceeds to S502.

  Next, in S502, the intake air amount is calculated (intake air amount is detected) based on the intake air amount detection signal measured by the air flow sensor 103, and the process proceeds to S503. In S503, the maximum target intake air amount is compared with the currently detected intake air amount. At this time, if it is determined that the current intake air amount is greater than or equal to the maximum target intake air amount, the process proceeds to S504.

  In S504, the throttle opening of the electric throttle 104 is controlled so that the intake air amount converges to the maximum target intake air amount. As a result, the actual intake air amount is suppressed to the vicinity of the maximum target intake air amount.

  The above control method will be described with reference to a timing chart shown in FIG. First, when the accelerator opening described above is opened by the driver's operation (601), the control unit 20 moves the valve body of the throttle valve to a predetermined position based on the accelerator opening so that the predetermined throttle opening is reached. To do. The intake air amount has an increase characteristic depending on the intake air temperature at that time, but in this figure, the intake air amount at the standard temperature (25 ° C.) and the low temperature is illustrated (604 at the standard temperature and 605 at the low temperature). .

  Here, since the accelerator opening is finally fully opened, the control unit 20 originally performs control so that the throttle opening also moves to the fully open position (602). However, since the intake air amount (605) has the maximum intake air amount (607) determined as the design value of the internal combustion engine, the intake air amount (605) at the low temperature is the maximum target intake air amount. When the control unit 20 determines that (608) has been exceeded, the control unit 20 controls the electric throttle valve so that the throttle opening is no longer opened. Further, the overshoot or undershoot is absorbed, and the intake air amount is finally converged to the maximum target intake air amount. As a result, the intake air amount is suppressed near the maximum target intake air amount (606). Since there is a margin between the maximum target intake air amount (608) and the maximum intake air amount (607), the intake air amount (606) does not exceed the maximum intake air amount (607).

  Further, in the above control example, the control example based on the target intake air amount described above has been described this time. However, when performing a predetermined calculation from the target intake air amount and controlling the electronically controlled throttle device, the target throttle opening degree is set. You may control. Further, when the internal combustion engine includes a variable valve that can change the moving characteristic of the intake valve, the lift amount of the intake valve, which is the variable valve, or the intake valve and the exhaust is controlled as described above. The aforementioned valve timing of the valve may be controlled. In addition, when the internal combustion engine is equipped with a device for forcibly supercharging the intake air amount such as a turbocharger or a supercharger and improving the engine output, the supercharging of this device is performed as the control described above. The pressure may be controlled. It is also possible to calculate the target value of the means for suppressing the intake air amount and the usage ratio or use condition of each means for suppressing the intake air amount, and use each means for suppressing the intake air amount simultaneously or stepwise. good.

  As a result, it is possible to guarantee the operation of the components constituting the direct injection engine, which is the subject of the present invention, and it is possible to ensure a use condition that does not exceed the aforementioned maximum intake air amount. However, although the control of the precondition only allows the intake air amount to be suppressed, the driver cannot expect the intake air amount above the target intake air amount even if the driver keeps stepping on the accelerator pedal with the intention of acceleration or the like. For this reason, the engine output reaches a peak, and a feeling of stall accompanying this occurs as a problem, and there is a possibility that the problem of drivability remains. Therefore, the control device according to the first embodiment is based on this control and further improves the control.

  FIG. 7 is a control flowchart according to the present embodiment. First, in S701, the control unit 20 calculates the density of air taken into the internal combustion engine based on the surrounding environment such as the intake air temperature, the outside air pressure, and the outside air temperature. In this calculation, for example, it may be calculated using a graph showing the relationship between the intake air temperature and the air density shown in FIG. 3 or a table showing these relationships, and the state equation is based on the intake air temperature and the intake air pressure. May be used to calculate the air density.

  Next, in S702, the maximum target intake air amount is calculated based on the air density. Specifically, first, the standard maximum target intake air amount to be sucked is preset in the standard state (25 ° C.) when the throttle opening is fully open. The standard maximum target intake air amount is a value that does not exceed the maximum intake air amount. Then, the maximum target intake air amount is calculated by multiplying the standard maximum target intake air amount by a coefficient related to the air density (for example, the reciprocal of the air density). The standard maximum target air amount and the maximum target intake air amount are preferably set to a unit equivalent to one stroke so as not to be affected by the increase or decrease of the intake air amount due to the fluctuation of the engine speed.

  Next, an accelerator opening ratio is calculated in S703. The accelerator opening ratio is obtained by using the voltage value detected by the accelerator opening sensor (hereinafter referred to as the accelerator opening detection value), “(accelerator opening detection value−voltage value when the accelerator is fully closed) ÷ (accelerator opening when the accelerator is fully open). (Voltage value−Voltage value when accelerator is fully closed) ”. This accelerator opening ratio corresponds to the ratio of the detected accelerator opening to the accelerator opening when fully opened. Note that the voltage value when the accelerator is fully opened and the voltage value when the accelerator is fully closed described here may be set in advance, or may be values learned by the control unit 20, either of which may be used. .

  Next, in S704, a target intake air amount that is a target is calculated. Based on the accelerator opening ratio calculated in S703 and the maximum target intake air amount calculated in S702, “accelerator opening ratio × maximum target intake air”. It is obtained by the formula “quantity”.

  Next, in S705, the throttle opening is controlled so that the intake air amount detected by the air flow sensor becomes the target intake air amount calculated in S704. Here, if the accelerator opening becomes constant, or if the accelerator opening is kept open and the target intake air amount is close to the maximum target intake air amount or matches the maximum target intake air amount, the detected intake air The amount is controlled so as not to exceed the maximum intake air amount.

  Specifically, in this embodiment, a maximum target intake air amount that is smaller than the maximum intake air amount is set (calculated) so that the maximum intake air amount is not exceeded, and the intake air amount is the maximum target air amount. Feedback control of the opening degree of the electric throttle valve is performed so as to converge to the intake air amount. As a result, it is possible to absorb the fluctuation of the intake air amount due to the increase and decrease of the intake air amount in the vicinity of the maximum target intake air amount and to prevent the intake air amount from exceeding the maximum intake air amount.

  FIG. 8 is a timing chart relating to the control content of FIG. The throttle opening (802) at a low temperature in the control method before the improvement has a change characteristic as illustrated based on the accelerator opening (801). The target intake air amount (808) by this control becomes a line of the change characteristic shown in FIG. 8, and exceeds the maximum intake air amount (maximum intake air amount (805) considering change in air density).

  Therefore, when control is performed so as not to exceed the maximum intake air amount described above, the change characteristic of the intake air amount is in the form of the target intake air amount (808) in FIG. 8 up to the maximum target intake air amount (806). The intake air amount increases, but the intake air amount reaches the maximum target intake air amount (806) by the time the accelerator opening is fully opened, resulting in a section that does not coincide with the accelerator depression amount of the driver. Become.

  On the other hand, as shown in FIG. 8, the target intake air amount is set based on the maximum target intake air amount (806) calculated in step S702 and the accelerator opening ratio calculated in step S703, and the detected intake air is set. The throttle opening of the electric throttle valve is controlled so that the amount becomes the target intake air amount. This is calculated as a ratio of the accelerator pedal depression amount of the driver with the range from the fully closed value to the fully opened value of the accelerator opening described above as a ratio, and this ratio is reflected in the target intake air amount to be controlled It is.

  That is, the ratio of the target intake air amount to the maximum target intake air amount calculated in consideration of the change in air density is equal to the accelerator opening ratio in the actual operation range. For example, when the ratio of the accelerator opening is 50% (position of 50% in the range from fully closed to fully open), the target intake air amount is also 50 with respect to the maximum target intake air amount. %.

  As a result, the intake air amount (807) becomes a characteristic line (809) having a more gradual increase characteristic than the conventional intake air amount (808) at a low temperature. Here, when the accelerator opening becomes constant, or when the accelerator opening continues to open and the target intake air amount is near the maximum target intake air amount or exceeds the preset maximum target intake air amount, The opening degree of the electric throttle valve is controlled so that the detected intake air amount does not exceed the maximum intake air amount (805) and the intake air amount converges to the maximum target intake air amount (806). Thereby, in the vicinity of the maximum target intake air amount, fluctuations in the intake air amount due to increase / decrease of the intake air amount can be absorbed.

  In this way, it is possible to overcome the drivability problem and avoid the use exceeding the above-mentioned maximum intake air amount based on the design values of the parts constituting the direct injection engine.

  Furthermore, in this embodiment, the lift amount of the intake valve may be adjusted so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully open. The opening and closing timings of the intake valve and the exhaust valve may be adjusted so that the amount converges to the aforementioned maximum target intake air amount. Further, the above-described intake air amount may be suppressed by calculating the target value of the means for controlling the intake air amount and the use ratio and use conditions of each control means for the intake air amount. In this way, it is possible to further improve the convergence of the intake air amount when the maximum target intake air amount is reached. Further, such a control method is more effective for a device that forcibly supercharges the intake air amount described above, such as a turbocharger or a supercharger, and improves the engine output.

  FIG. 9 is a flowchart of the control device according to the second embodiment, and FIG. 10 is a timing chart relating to the control contents of FIG. The second embodiment is different from the first embodiment in that the throttle opening is directly controlled instead of the target intake air amount.

  First, in S901, the control unit 20 calculates the density of air sucked into the internal combustion engine based on the surrounding environment such as the intake air temperature, the outside air pressure, and the outside air temperature. This method is the same method as in the first embodiment.

  Next, in S902, the maximum target throttle opening is calculated based on the air density. As an example of the calculation method of the maximum target throttle opening, after calculating the air density in S901, the basic intake air amount (intake air amount in a standard state) based on a preset throttle opening is multiplied by the air density, The maximum throttle opening at which the multiplied intake air amount does not exceed the preset maximum intake air amount is set as the maximum target throttle opening. For this maximum target throttle opening, a maximum throttle opening corresponding to the maximum intake air amount (a preset maximum allowable intake air amount in the design as described above) is set in advance, and this maximum throttle opening is set. It is good also as a throttle opening which does not exceed an opening.

  Next, in S903, the accelerator opening ratio is calculated. The accelerator opening ratio is obtained by using the voltage value detected by the accelerator opening sensor (hereinafter referred to as the accelerator opening detection value) as “(the voltage of the accelerator opening detection value (the voltage value when detected by the accelerator opening sensor). )-Voltage value when accelerator is fully closed) / (voltage value when accelerator is fully open-voltage value when accelerator is fully closed) ". This accelerator opening ratio corresponds to the ratio of the detected accelerator opening to the accelerator opening when fully opened. It should be noted that the voltage value when the accelerator is fully opened and the voltage value when the accelerator is fully closed described here may be set in advance, or may be values learned by the control unit 20, either of which may be used. .

  Next, in S904, the target throttle opening is calculated, which is the accelerator opening ratio calculated in S903 and the voltage value of the throttle opening sensor (the sensor voltage corresponding to the maximum target throttle opening calculated in S902). The value of the accelerator ratio x (the maximum target throttle opening voltage value−the voltage value when the throttle is fully closed) + the voltage value when the throttle is fully closed ”is calculated based on the following equation. Note that the voltage value when the throttle is fully opened and the voltage value when the throttle is fully closed described here may be set in advance, or may be values learned by the control unit 20, either of which may be used. .

  Next, in S905, the throttle opening is controlled so that the throttle opening detected by the throttle opening sensor becomes the target throttle opening obtained in S904. Here, when the accelerator opening becomes constant or when the accelerator opening continues to open and the target throttle opening is close to or coincides with the maximum target throttle opening, the throttle opening overshoots or undershoots. The chute is absorbed and finally the throttle opening is converged to the maximum target throttle opening or near the maximum target throttle opening. Specifically, feedback control of the electric throttle valve is performed so that the throttle opening converges to the maximum target throttle opening when the accelerator opening is fully open. As a result, it is possible to absorb the fluctuation of the intake air amount due to the increase and decrease of the intake air amount in the vicinity of the maximum target intake air amount and to prevent the intake air amount from exceeding the maximum intake air amount.

  FIG. 10 is a timing chart relating to the control content of FIG. The throttle opening (1002) at a low temperature in the control method before the improvement has a change characteristic as shown in the figure based on the accelerator opening (1001), as described above. The target intake air amount (1008) by this control becomes a line of the change characteristic shown in FIG. 8, and exceeds the maximum intake air amount (maximum intake air amount (1005) considering change in air density).

  Therefore, when control is performed so as not to exceed the above-described maximum intake air amount, the change characteristic of the intake air amount is in the form of the target intake air amount (1008) in FIG. 10 up to the maximum target intake air amount (1006). However, although the intake air amount increases, the intake air amount reaches the maximum target intake air amount (1006) by the time the accelerator opening is fully opened, resulting in a section that does not coincide with the driver's accelerator depression amount. become.

  On the other hand, as shown in FIG. 10, based on the maximum target throttle opening (1003) calculated in step S902 and the accelerator opening ratio calculated in S903, the detected throttle opening is the target throttle opening. Thus, the throttle opening of the electric throttle valve is controlled. In this case, the range from the fully closed value to the fully opened value of the accelerator opening is calculated as 100%, and the depression amount of the driver's accelerator pedal is calculated as a ratio, and this ratio is reflected in the target throttle opening.

  That is, the ratio of the target throttle opening to the maximum target throttle opening calculated in consideration of the change in air density is equal to the ratio of the accelerator opening in the actual operation range. For example, when the ratio of the accelerator opening described above is 50% (a position of 50% within the range from fully closed to fully open), the target throttle opening is similarly 50% of the maximum target throttle opening. %.

  As a result, the intake air amount (1007) becomes a characteristic line having a more gradual increase characteristic than the conventional intake air amount (1008) at a low temperature. Here, when the accelerator opening becomes constant, or when the accelerator opening keeps opening and the target throttle opening becomes close to the maximum target throttle opening, the detected throttle opening becomes the maximum target throttle. The throttle opening of the electric throttle valve is controlled so that the opening (1003) is not exceeded and the target throttle opening converges to the maximum target throttle opening (1003). Thereby, overshoot and undershoot can be absorbed, and the opening degree of the electric throttle valve can be finally controlled in the vicinity of the maximum throttle opening degree.

  In this way, it is possible to overcome the drivability problem and avoid the use exceeding the above-described maximum intake air amount based on the design values of the components constituting the direct injection engine.

  Furthermore, in this embodiment, the lift amount of the intake valve may be adjusted so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully open. The opening and closing timings of the intake valve and the exhaust valve may be adjusted so that the amount converges to the aforementioned maximum target intake air amount. Further, the above-described intake air amount may be suppressed by calculating the target value of the means for controlling the intake air amount and the use ratio and use conditions of each control means for the intake air amount. In this way, it is possible to further improve the convergence of the intake air amount when the maximum target intake air amount is reached. Further, such a control method is more effective for a device that forcibly supercharges the intake air amount described above, such as a turbocharger or a supercharger, and improves the engine output.

1 is an overall configuration diagram of a direct injection engine according to a first embodiment of the present invention. The block diagram which shows the relationship between the direct-injection engine shown in FIG. 1, and a control unit (ECU). The figure for demonstrating the relationship between a temperature and the change of an air density curve. The figure for demonstrating the change of the intake air amount accompanying a temperature change. The flowchart for demonstrating the control used as the premise of the control apparatus of 1st embodiment. 6 is a timing chart when the control shown in FIG. 5 is performed. The flowchart for demonstrating control of the control apparatus of 1st embodiment. The timing chart at the time of performing control shown in FIG. The flowchart for demonstrating control of the control apparatus of 2nd embodiment. The timing chart at the time of performing control shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Engine main body 102 ... Intake path 103 ... Air flow sensor 104 ... Electric throttle 105 ... Throttle opening sensor 106 ... Collector 107 ... TGV (tumble generated valve)
108 ... Partition plate 109 ... Intake valve 110 ... Exhaust valve 111 ... Combustion chamber 112 ... Piston 113 ... Connecting rod 114 ... Flywheel 115 ... Crank angle sensor 116a ... Camshaft (intake cam)
116b ... camshaft (exhaust cam)
117a, 117b ... cam angle sensor 118 ... fuel path 119 ... high pressure fuel pump 120 ... gallery 121 ... fuel pressure sensor 122 ... fuel injection valve (injector)
123 ... Ignition coil 124 ... Ignition plug 125 ... Exhaust path 126 ... Air-fuel ratio sensor 127 ... Catalyst

Claims (7)

An accelerator opening detecting means for detecting the accelerator opening; a throttle valve for adjusting the intake air amount; an intake air amount detecting means for detecting the intake air amount; a temperature detecting means for detecting the intake air temperature of the internal combustion engine; A control device for an in-cylinder internal combustion engine comprising:
The control device includes: an air density calculation unit that calculates a density of air that is sucked based on at least the intake air temperature; a maximum target intake air amount calculation unit that calculates a maximum target intake air amount based on the air density; An accelerator opening ratio calculating means for calculating a ratio of the accelerator opening with respect to an accelerator opening when fully open; a means for calculating a target intake air amount by multiplying the maximum target intake air amount by the accelerator opening ratio; A control apparatus for a cylinder injection type internal combustion engine, comprising: a throttle valve control means for controlling the throttle valve so that an intake air amount becomes the target intake air amount.   2. The internal combustion engine according to claim 1, wherein the throttle valve control means controls the throttle valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully opened. Engine control device.   The control device further includes lift amount adjusting means for adjusting a lift amount of an intake valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully opened. The control apparatus for an internal combustion engine according to claim 2.   The control device further includes valve timing adjustment means for adjusting opening / closing timings of the intake valve and the exhaust valve so that the intake air amount converges to the maximum target intake air amount when the accelerator opening is fully opened. The control device for an internal combustion engine according to claim 2 or 3, wherein the control device is an internal combustion engine.   The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the internal combustion engine includes a supercharging device for forcibly supercharging at least the intake air amount. Accelerator opening detecting means for detecting the accelerator opening, a throttle valve for adjusting the intake air amount, a throttle opening detecting sensor for detecting the throttle opening of the throttle valve, and a temperature detection for detecting the intake air temperature of the internal combustion engine A control device for a cylinder injection internal combustion engine comprising:
The control device includes: an air density calculation unit that calculates a density of air that is sucked based on at least the intake air temperature; a maximum target throttle opening calculation unit that calculates a maximum target throttle opening based on the air density; Accelerator opening ratio calculating means for calculating the ratio of the accelerator opening to the accelerator opening when fully open, and the target throttle opening for calculating the target throttle opening by multiplying the maximum target throttle opening by the accelerator opening ratio And a throttle valve control means for controlling the throttle valve so that the throttle opening becomes the target throttle opening.   7. The internal combustion engine according to claim 6, wherein the throttle valve control means controls the throttle valve so that the throttle opening converges to the maximum target throttle opening when the accelerator opening is fully opened. Engine control device.

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