JP2005194941A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, for reducing pumping loss to improve fuel economy, in an internal combustion engine in which a throttle valve for each cylinder is disposed to an independent intake pipe. <P>SOLUTION: This control device comprises: the independent intake pipes 5a to 5d supplying intake air to each cylinder 1a to 1d of the internal combustion engine 1; individual intake amount control means 9a to 9d disposed to the independent intake pipes 5a to 5d to control an effecting intake passage cross-sectional area for each cylinder; fuel injection valves 7a to 7d controlling a fuel supply amount for each cylinder; and a control means 14 calculating the fuel injection amounts with respect to a plurality of cylinders for each cylinder to control the fuel injection valves 7a to 7d, and calculating intake amounts with respect to the cylinders for each cylinder to control the individual intake amount control means 9a to 9d. The control of the individual intake amount control means 9a to 9d by the control means 14 is set so that the cross-sectional area of the intake passage is large during a predetermined period in which intake valves 6a to 6d of the corresponding cylinders are closed, and the cross-sectional area is small when the intake valves 6a to 6d are opened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine control device capable of reducing a pumping loss of an internal combustion engine for a vehicle and improving fuel consumption.

  In a multi-cylinder internal combustion engine used in a vehicle, etc., an independent intake pipe (intake branch pipe) is provided for each cylinder of the internal combustion engine for each cylinder, and a throttle valve is provided in each independent intake pipe for output control. A so-called multiple throttle valve is known. Thus, by providing a throttle valve in each independent intake pipe, the internal volume of the intake pipe on the downstream side of the throttle valve can be reduced, and the response of the pressure in the intake pipe to the control of the throttle valve opening is improved. The output response of the internal combustion engine can be improved.

  However, such a multi-throttle valve internal combustion engine has a throttle which is particularly low in a low rotation and low load state such as idle operation, as compared with a single throttle valve internal combustion engine in which a single throttle valve is arranged in the intake pipe assembly. The gain of the intake air amount change with respect to the change in the valve opening increases, so the output change of the internal combustion engine with respect to the change in the throttle valve opening also increases, and subtle control of each throttle valve is necessary to obtain stable rotation. There is a problem that it becomes difficult to smoothly operate the internal combustion engine when the throttle valve cannot be delicately controlled.

  The technique disclosed in Patent Document 1 addresses such a problem. In an internal combustion engine provided with multiple throttle valves that are linked to and linked to each independent intake pipe provided in each cylinder, each throttle A balance passage communicating between the independent intake pipes is provided on the downstream side of the valve. The balance passage is integrated into a collecting pipe to communicate with a collecting portion of the intake pipe on the upstream side of the throttle valve, and an electromagnetic valve is connected to the collecting pipe. And the stability of rotational fluctuation is improved by controlling the electromagnetic valve on and off in a low rotation range. However, it is difficult to maintain the opening of each throttle valve constant due to variations and aging in a multiple throttle valve in which each throttle valve is connected and linked as in this document.

  In addition, the technique disclosed in Patent Document 2 is such that an independent intake pipe is provided for each cylinder of the internal combustion engine, and a throttle valve is provided for each independent intake pipe. This pressure is established by connecting the downstream side and the upstream side of the throttle valve (collection part of the intake pipe) through an intake communication passage having a control valve, and detecting the pressure downstream of the control valve in the intake communication passage to open and close the control valve. In addition, the intake air amount is calculated based on the corrected pressure, and for sudden changes in the control valve opening, the convergence correction value is obtained from the map and the calculated value is corrected to increase the intake air amount. The accuracy is set.

JP-A-63-306252 (2nd page, FIGS. 1 to 3) JP 07-77440 A (pages 3-6, FIGS. 1-8)

  In an internal combustion engine for a vehicle, EGR (exhaust gas recirculation) gas, blow-by gas, etc. are introduced as part of exhaust gas countermeasures, and these substances exist in the intake pipe for a long period of time. As a result, the throttle valve It is known to close or reduce the effective gap serving as the intake passage. Since it is difficult to generate such pollutant effects evenly among the cylinders, even if the opening of each throttle valve is adjusted precisely at the initial stage, the intake air supply to each cylinder will change over time. The amount becomes different, and it is difficult to correct this uneven intake amount with a multiple throttle valve configured to be linked to each other.

  As for the pumping loss that affects the output efficiency of the internal combustion engine, a type in which a throttle valve for each cylinder is arranged in each independent intake pipe in contrast to an internal combustion engine in which a single throttle valve is arranged in the collection section of the intake pipe. Is known to be less. The pumping loss is energy lost by sucking air that has dropped below the atmospheric pressure downstream of the throttle valve in the intake stroke into the cylinder and discharging it into the exhaust pipe under atmospheric pressure in the exhaust stroke. This loss energy is reduced as a relatively large loss in an internal combustion engine in which a throttle valve for each cylinder is arranged in each independent intake pipe, but is reduced as compared with an internal combustion engine having a single throttle valve. As a result, fuel consumption can be improved.

  The present invention has been made to solve such a problem. In an internal combustion engine in which a throttle valve for each cylinder is arranged in each independent intake pipe, it is possible to further reduce pumping loss and improve fuel efficiency. An object of the present invention is to obtain an internal combustion engine control device.

  An internal combustion engine control apparatus according to the present invention is provided in each of an independent intake pipe for supplying intake air to each of a plurality of cylinders of the internal combustion engine, and an independent intake pipe, and each intake passage cross-sectional area is determined by its opening degree. An individual intake air amount control means that individually controls the fuel, a fuel injection valve that individually supplies fuel to a plurality of cylinders, an intake valve provided at a joint portion between the plurality of cylinders and the independent intake pipe, and an intake valve A cylinder identification sensor that discriminates the opening / closing operation for each cylinder, and a control unit that calculates the intake air amount and the fuel supply amount of the independent intake pipe and controls the individual intake air amount control unit and the fuel injection valve based on the calculation result. And the control means sets the intake passage cross-sectional area during a period when the intake valve is in a closed state to be larger than the intake passage cross-sectional area when the intake valve is in an open state.

  In the internal combustion engine control apparatus configured as described above, an individual intake air amount control means for individually controlling the intake passage cross-sectional area is provided for each cylinder so that the intake air amount for each cylinder can be independently controlled. Since the intake passage cross-sectional area is set to be larger during the predetermined period when the intake valve is in the closed state than when the intake valve is in the open state, the intake air amount of each cylinder is individually controlled to accurately control the air-fuel ratio. Can be controlled to obtain a stable rotation without change over time even in a low speed rotation region, and the intake pipe pressure on the downstream side of the throttle valve of each independent intake pipe at the beginning of the intake stroke can be increased. The pumping loss can be greatly reduced, and an internal combustion engine control device with excellent fuel efficiency can be obtained.

Embodiment 1 FIG.
1 to 6 are diagrams for explaining an internal combustion engine control apparatus according to Embodiment 1 of the present invention. FIG. 1 is a schematic configuration diagram of an intake / exhaust passage of the internal combustion engine, and FIG. 2 is a description of pumping loss. FIG. 3 is a comparative explanatory diagram showing the pressure in the intake pipe between the case of the independent throttle valve and the case of the single throttle valve, and FIG. 4 is a diagram of the case of the independent throttle valve and the case of the single throttle valve. FIG. 5 is a PV diagram for explaining the difference in pumping loss between the intake pipes, FIG. 5 is a graph showing the fluctuations in the intake pipe pressure according to the first embodiment of the present invention, and FIG. 6 is the internal combustion engine control of the present invention. It is explanatory drawing which shows the pressure in an intake pipe at the time of acceleration / deceleration by an apparatus.

  The schematic configuration diagram of FIG. 1 is an example of a four-cylinder internal combustion engine, and will be described for a four-cylinder internal combustion engine, including the following operation description. In the figure, an internal combustion engine 1 has four cylinders 1a to 1d, and an intake pipe 2 for supplying intake air to the cylinders 1a to 1d forms an intake pipe assembly 4 having an air cleaner 3 at an upstream portion thereof. The cylinders 1a to 1d are configured such that independent intake pipes (intake branch pipes) 5a to 5d that are branched from the intake pipe collecting portion 4 supply intake air to the respective cylinders. Intake valves 6a to 6d are provided at the joints with the independent intake pipes 5a to 5d.

  Each of the independent intake pipes 5a to 5d has a fuel injection valve 7a to 7d for supplying fuel to each cylinder from the downstream side, an intake pressure sensor 8a to 8d for detecting the intake amount for each cylinder, and an accelerator pedal (not shown). ETVs 9a to 9d, which are electronically controlled throttle valves for controlling the throttle opening for each cylinder based on the operation amount, are provided. These ETVs 9a to 9d serve as the individual intake air amount control means for determining the effective sectional area of the intake passage for each cylinder. To control. Further, an exhaust pipe 11 is joined to each cylinder 1a to 1d via exhaust valves 10a to 10d, and an air-fuel ratio sensor 12 for detecting an air-fuel ratio of the internal combustion engine 1 is provided at a collecting portion of the exhaust pipe 11. ing. The internal combustion engine 1 is provided with a cylinder identification sensor 13 that discriminates the intake stroke of each cylinder and detects the rotational speed of the internal combustion engine 1.

  The control means 14 inputs information such as the rotational speed and crank angle of the internal combustion engine 1 from the cylinder identification sensor 13 to calculate the ignition timing, controls the ignition system (not shown), and controls the operation amount and the suction of an accelerator pedal (not shown). The intake air amount is calculated for each cylinder based on the output of the atmospheric pressure sensors 8a to 8d, and the throttle opening of the ETVs 9a to 9d is controlled based on the calculated intake air amount for each cylinder and the cylinder discrimination signal output from the cylinder identification sensor 13. . Further, the control means 14 calculates an appropriate fuel supply amount for each cylinder 1a to 1d from the intake air amount for each cylinder and the cylinder identification signal of the cylinder identification sensor 13, and controls the fuel injection valves 7a to 7d.

  The intake air distributed to the independent intake pipes 5a to 5d via the air cleaner 3 is controlled by the ETVs 9a to 9d and supplied to the cylinders 1a to 1d. Since the air pressure of the intake air changes depending on the throttle opening of the ETVs 9a to 9d, the intake air amount of each cylinder 1a to 1d is the intake pressure detected by the intake pressure sensors 8a to 8d and the internal combustion engine 1 detected by the cylinder identification sensor 13. It can be detected from the rotational speed. The control of the ignition system (not shown) by the control means 14 is controlled so as to perform ignition in the MBT or in the vicinity of the MBT corresponding to the environment of the internal combustion engine 1.

  The control of the intake air amount and the fuel injection amount by the control means 14 is feedback control based on the output signal of the air-fuel ratio sensor 12 provided in the collective portion of the exhaust pipe 11, whereby the intake air amount from the ETVs 9a to 9d is changed over time. Even if there is variation due to changes, the excess or deficiency between the fuel injection amount and the intake air amount is calculated, the throttle valve opening of the ETVs 9a to 9d is controlled, and the air-fuel ratio is controlled with high accuracy by correcting the variation of the intake air amount. To do.

  Further, the control means 14 controls the throttle valve openings of the ETVs 9a to 9d as follows. That is, during a predetermined period in which the intake valves 6a to 6d are closed, the opening of the throttle valve is controlled in the direction in which the intake passage is expanded from the command opening based on the accelerator operation, and the independent intake downstream of the throttle valve is controlled. The negative pressure of the pipe is reduced, the intake valves 6a to 6d are opened, and the throttle valve opening is controlled and changed so that the intake passage is reduced. The overall intake amount is controlled to the intake amount based on the accelerator operation. The pumping loss is reduced while maintaining the air-fuel ratio. For example, even if the driver performs an accelerator operation and the vehicle is in an accelerated state, control is performed to change the throttle opening, maintaining acceleration based on the accelerator operation, reducing pumping loss, and reducing fuel consumption. Reduce.

  The pumping loss will be described with reference to the PV diagram of FIG. 2. The diagram is a diagram showing the pressure in the cylinder (inside the cylinder) in each stroke of intake, compression, combustion, and exhaust, of which the intake in the negative pressure state The difference in pressure between the intake stroke that is sucked from the pipe and the exhaust stroke that is discharged to the exhaust pipe at atmospheric pressure is the pumping loss. The pumping loss reduces the negative pressure value in the intake pipe during the intake stroke. Can be reduced. As shown in FIG. 3, an independent throttle valve that can be individually controlled for each of an internal combustion engine (hereinafter referred to as a single throttle valve) of a type in which a single throttle valve is arranged at a collecting portion of the intake pipe and an independent intake pipe. In the case of a single throttle valve, the negative pressure continues to be almost constant and each cylinder has a constant negative pressure. While intake is performed from the pressure value, the pressure in the intake pipe in the case of the independent throttle valve varies from a negative pressure value smaller than that in the case of the single throttle valve to a value close to the negative pressure of the single throttle valve.

  This will be explained with reference to the PV diagram of FIG. 4. FIG. 4 is a PV diagram in which the change in the cylinder pressure is compared between an internal combustion engine with a single throttle valve and an internal combustion engine with an independent throttle valve. In this case, since one of the four cylinders is always in the intake stroke and the air in the intake pipe flows into one of the cylinders, the intake stroke is as shown in the diagram (b) of the figure. The cylinder pressure at is always low. In contrast, in the case of an independent throttle valve, the intake pipe of each cylinder is independent, so there is no interference of intake air between the cylinders, and when the intake stroke is completed and the intake valve is closed, the air is drawn from the throttle valve into the intake pipe. Flows in and the intake pipe pressure rises. As a result, as shown in FIG. 4A, the cylinder pressure immediately after the start of the intake stroke becomes higher than that in the case of a single throttle valve, and the atmospheric pressure decreases with the progress of intake. The hatched portions (A) and (B) in the figure are the difference, and since the (A) portion is larger than the (B) portion, the average pressure is higher than in the case of a single throttle valve, and the pumping loss is that of the independent throttle valve. Is smaller.

  As described above, the pumping loss in the independent throttle valve is smaller than that in the single throttle valve because the intake pipe pressure immediately after the start of the intake stroke is high. Therefore, the pumping loss can be further reduced by increasing the intake pipe pressure immediately after the start of the intake stroke. As described above, in the internal combustion engine controller according to Embodiment 1 of the present invention, in each cylinder, the control means 14 operates the throttle valve opening for a predetermined period in which the intake valves 6a to 6d are closed. Therefore, the cross-sectional area of the intake passage that is set by operating the accelerator pedal is controlled so that the pressure in the intake pipe increases, and the pumping loss can be greatly reduced to improve fuel efficiency. .

  FIG. 5 (a) shows changes in the intake pipe pressure when controlled in this way. In the case of an independent throttle valve in which the opening operation is performed together with the opening and closing of the intake valve according to the present invention, an intake air as a comparative example is shown. The pressure characteristics in the intake pipe are shown together with the case of an independent throttle valve in which the opening operation is not performed together with the opening and closing of the valve. In the case of the independent throttle valve according to the present invention, the intake pipe pressure increases from the time (t1) when the intake valve is closed, so that the amount of inflow air becomes larger than the comparative example because the throttle opening increases, and the intake valve opens. Although the intake pipe pressure starts to decrease due to the intake air, the pumping loss decreases because it maintains a higher value than the comparative example.

  FIG. 5 (b) shows the change in the throttle valve opening. In the case of the independent throttle valve according to the present invention, the throttle opening begins to increase at the time (t1) when the intake valve closes, and becomes a constant value. To settle down. This constant value is maintained for a predetermined period, and when the predetermined time (t2) within the intake valve closing period is reached, the throttle opening decreases to the original opening. On the other hand, in the comparative example, since the opening operation is not performed simultaneously with the opening and closing of the intake valve, as shown by the chain line in FIG. 5, it is constant regardless of the opening and closing of the intake valve.

FIGS. 5C and 5D show other control methods of the throttle opening. FIG. 5 (c) shows a case where the throttle opening is large during the intake valve closing period, and the throttle opening is small during the intake valve opening period. The difference with respect to the comparative example is smaller. FIG. 5 (d) shows an example in which the opening is gradually increased or decreased without being fixed to a constant value when the throttle opening is similarly controlled. As described above, there are various control methods, but in any case, the throttle opening is controlled to be large during the predetermined period when the intake valve is closed, and the throttle opening is decreased during the intake valve opening period. The large opening period is set longer than the small opening period.

  FIG. 6 illustrates the operation when the accelerator operation is performed so that the vehicle accelerates or decelerates. In the acceleration state, air is introduced into the intake pipe before the intake valves 6a to 6d are opened to increase the pressure in the intake pipe so that the intake air necessary for generating the required torque is sucked into the cylinder in the first half of the intake stroke. Each ETV 9a to 9d operates as described above. Similarly, in the deceleration state, in order to inhale into the cylinder in the first half of the intake stroke, air is introduced into the intake pipe before each intake valve 6a to 6d is opened to increase the pressure in the intake pipe. Works. Therefore, the pumping loss can be reduced and the power performance can be improved in the acceleration state and the deceleration state.

Embodiment 2. FIG.
FIG. 7 is an explanatory view illustrating the operating state of the throttle valve of the internal combustion engine control apparatus according to Embodiment 2 of the present invention. The internal combustion engine control apparatus according to this embodiment is obtained by adding a control function for controlling the air-fuel ratio to an optimum state to the control means 14. During a transient operation such as an acceleration / deceleration state of the internal combustion engine, a state in which the control of the fuel supply amount by the control means 14 cannot be performed with respect to a change in the intake air amount due to the accelerator operation occurs. That is, as described above, the control means 14 calculates the intake amount for each cylinder based on the operation amount of the accelerator pedal, the outputs of the intake pressure sensors 8a to 8d, and the rotational speed of the internal combustion engine 1, and calculates the ETVs 9a to 9d. In addition to controlling, the fuel supply amount is calculated and the fuel injection valves 7a to 7d are controlled to supply air and fuel based on a predetermined air-fuel ratio. In some cases, the amount of operation of the accelerator pedal may change after the fuel supply by the injection valves 7a to 7d is started. In such a case, the throttle opening changes even though the fuel injection amount cannot be changed. Therefore, a predetermined air / fuel ratio may not be maintained.

  In such a case, the control means 14 controls the ETVs 9a to 9d during the period in which the fuel supply amount cannot be corrected, prohibits changes in the throttle opening, and after the period during which the fuel supply amount can be controlled. Operates to control the throttle opening. The period during which the fuel supply amount cannot be controlled or corrected is after the calculation of the fuel injection amount is completed or until the intake valve of the cylinder is closed after the fuel injection starts. Then, after the intake valve is closed, the throttle opening is controlled based on the operation amount of the accelerator pedal. By this control, the change in the intake air amount with respect to the fuel injection amount is suppressed, and the deterioration of the exhaust gas due to the change in the air-fuel ratio can be suppressed to the minimum.

  In the conventional control, the same state is corrected by asynchronous fuel injection, but sufficient correction cannot be made in terms of time, and exhaust gas and drivability cannot be sufficiently improved. In the internal combustion engine control apparatus according to this embodiment, as described above, during the period in which the control unit 14 cannot correct the fuel supply amount, that is, after the start of fuel injection or after calculation of the fuel injection amount, the ETVs 9a to 9d are used. The change of the intake passage cross-sectional area is prohibited, the intake passage cross-sectional area before the start of fuel injection is maintained, and this is continued until the intake valves 6a to 6d of the internal combustion engine 1 are closed, and the intake valves 6a to 6d are closed. After that, the throttle valve opening based on the operation amount of the accelerator pedal is restored, so that the air-fuel ratio can be maintained, and deterioration of exhaust gas and drivability can be prevented.

  As described above, the internal combustion engine control device of the present invention is intended to improve the control accuracy of the air-fuel ratio and reduce the pumping loss during the transient operation of the internal combustion engine 1. In order to reduce the pumping loss, the intake air in the independent intake pipes 5a to 5d on the downstream side of the ETVs 9a to 9d is increased while the intake valves 6a to 6d are closed. For this purpose, the intake passage cross-sectional area is increased. In order to improve the air-fuel ratio control accuracy, it is necessary to prohibit changes in the intake passage cross-sectional area during the period in which the fuel injection amount cannot be corrected, and in synchronization with the rotation of the internal combustion engine 1. Thus, the ETVs 9a to 9d are finely controlled. However, when the load is high, the pumping loss is extremely small, and in the high speed rotation range, the stroke period is shortened and the absolute amount of the intake air amount control is reduced. Therefore, either or both of the rotation speed and the load amount are over a predetermined value. In this case, the control of the ETVs 9a to 9d can be stopped, and in this case, sufficient control can be performed even with an inexpensive ETV.

  The internal combustion engine control apparatus according to the present invention can be applied to an electric ignition type internal combustion engine for a vehicle, a marine internal combustion engine, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of an internal combustion engine intake / exhaust passage for explaining an internal combustion engine control apparatus according to Embodiment 1 of the present invention; It is a PV diagram explaining a pumping loss. It is comparison explanatory drawing which shows the intake pipe internal pressure of an independent throttle valve and a single throttle valve. It is a PV diagram explaining the difference of the pumping loss of an independent throttle valve and a single throttle valve. FIG. 3 is an intake pipe pressure fluctuation diagram comparing the internal combustion engine control apparatus according to Embodiment 1 of the present invention and a conventional example. It is explanatory drawing which shows the intake pipe internal pressure at the time of the acceleration of the internal combustion engine control apparatus by Embodiment 1 of this invention. It is explanatory drawing of the throttle-valve operating state of the internal combustion engine control apparatus by Embodiment 2 of this invention.

Explanation of symbols

1 internal combustion engine, 1a to 1d cylinder, 2 intake pipe, 3 air cleaner,
4 Intake pipe assembly, 5a to 5d Independent intake pipe,
6a to 6d intake valve, 7a to 7d fuel injection valve,
8a to 8d intake pressure sensor, 9a to 9d ETV (individual intake air amount control means),
10a to 10d exhaust valve, 11 exhaust pipe, 12 air-fuel ratio sensor,
13 cylinder identification sensor, 14 control means.

Claims (5)

  An independent intake pipe for supplying intake air to each of a plurality of cylinders of an internal combustion engine, and an individual intake air amount control means for individually controlling the cross-sectional area of each intake passage by its opening degree , A fuel injection valve that individually supplies fuel to the plurality of cylinders, an intake valve provided at a joint portion between the plurality of cylinders and the independent intake pipe, and a cylinder that determines opening / closing operation of the intake valve for each cylinder An identification sensor; and a control unit that calculates an intake air amount and a fuel supply amount of the independent intake pipe and controls the individual intake air amount control unit and the fuel injection valve based on a result of the calculation. An internal combustion engine control device, wherein an intake passage cross-sectional area during a period in which the intake valve is in a closed state is set to be larger than an intake passage cross-sectional area in which the intake valve is in an open state.   The control means sets the opening of the individual intake air amount control means to an intake passage cross-sectional area of a first opening when the internal combustion engine is in a steady operation state and the intake valve is open, When the intake valve shifts from the open state to the closed state, the individual intake air amount control means is set to an intake passage cross-sectional area with a second opening larger than the intake passage cross-sectional area with the first opening and held for a predetermined time. The internal combustion engine control device according to claim 1.   When the intake valve shifts to a closed state when the internal combustion engine is in an output increase state such as an acceleration operation, the control means changes the opening of the individual intake air amount control means from a third opening to a fourth opening. When the intake passage cross-sectional area is gradually increased and the intake valve shifts from the closed state to the open state, the opening of the individual intake air amount control means is changed from the fourth opening to the fifth opening larger than the third opening. The internal combustion engine control device according to claim 1 or 2, wherein the internal combustion engine control device is gradually decreased to an opening degree. When the intake valve shifts to a closed state when the internal combustion engine is in an output decreasing state such as a deceleration operation, the control means changes the opening of the individual intake air amount control means from a third opening to a fourth opening. When the intake passage cross-sectional area is gradually increased and the intake valve shifts from the closed state to the open state, the opening of the individual intake air amount control means is changed from the fourth opening to the sixth opening smaller than the third opening. The internal combustion engine control device according to claim 1 or 2, wherein the internal combustion engine control device is gradually decreased to an opening degree.   When the intake valve is in a closed state and the fuel injection by the fuel injection valve is started, the control means opens the individual intake air amount control means until the next closed state of the intake valve is started. The internal combustion engine control device according to claim 3 or 4, wherein

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