JP2012219799A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine that can suppress acceleration shock caused by changes in the air volume in a cylinder.SOLUTION: The control device of an internal combustion engine is mounted on a vehicle and includes an engine, a throttle valve, a throttle valve control means and a throttle valve opening time limiting means. The throttle valve control means controls to open and close a throttle valve. The throttle valve opening time limiting means limits an opening time of the throttle valve by the throttle valve control means. The throttle valve opening time limiting means sets a start time to permit opening of the throttle vale to a delay angle side with the lower engine speed.

Description

  The present invention relates to control of a vehicle including an internal combustion engine.

  Conventionally, a small-cylinder engine with a small number of cylinders is known. For example, Patent Document 1 discloses a two-cylinder engine in which the crank angle is set to have a phase difference of 360 degrees. In Patent Document 2, a target throttle opening at the end of acceleration is set when acceleration is requested, the throttle opening is held at a side smaller than the target throttle opening during acceleration, and then the throttle opening is opened. Techniques that change every time are disclosed. Further, Patent Document 3 discloses a technique for making the throttle opening smaller than the target throttle opening for a predetermined period during acceleration.

JP 2010-275990 A JP 2008-223511 A Japanese Patent Laid-Open No. 10-047125

  In an engine with a small number of cylinders such as a two-cylinder engine, intake pulsation occurs due to the long time interval of the intake stroke and the close interval of the intake valve, and the prediction accuracy of the in-cylinder air amount It becomes difficult to secure. In addition, if the time interval of the intake stroke is long and the time from opening the throttle valve to closing the intake valve is long, the change in the in-cylinder air amount becomes large, and the time when the throttle valve is closed There is a risk of acceleration shock.

  The present invention has been made to solve the above-described problems, and a main object of the present invention is to provide a control device for an internal combustion engine that can suppress acceleration shock caused by a change in the in-cylinder air amount. And

  In one aspect of the present invention, an engine, a throttle valve provided in an intake passage of the engine, throttle valve control means for controlling opening and closing of the throttle valve, and opening of the throttle valve by the throttle valve control means A throttle valve opening timing limiting means for performing control for limiting the timing, wherein the throttle valve opening timing limiting means is configured to reduce the throttle valve as the engine speed decreases. The start timing for permitting the opening of the throttle valve by the control means is set to the retard side.

  The above control device for an internal combustion engine is mounted on a vehicle and includes an engine, a throttle valve, throttle valve control means, and throttle valve opening timing limiting means. The throttle valve control means is, for example, an ECU (Electronic Control Unit) and controls the opening and closing of the throttle valve. The throttle valve opening timing control means is, for example, an ECU, and limits the opening timing of the throttle valve by the throttle valve control means. Then, the throttle valve opening timing control means sets the start timing for permitting the opening of the throttle valve to the retard side as the engine speed decreases.

  Generally, the lower the engine speed, the longer the intake stroke time interval and the longer the intake valve closing interval. Therefore, the control device for the internal combustion engine delays the opening timing of the throttle valve by setting the start timing for allowing the opening of the throttle valve to be retarded as the engine speed is lower. Thus, the control device for the internal combustion engine can suppress an increase in the time width between the opening timing of the throttle valve and the closing timing of the intake valve. Therefore, the control device for the internal combustion engine can suppress the acceleration shock caused by the excessive change in the in-cylinder air amount.

  In one aspect of the control apparatus for an internal combustion engine, the throttle valve opening timing limiting means performs control for limiting the valve opening timing when the required opening of the throttle valve is equal to or greater than a predetermined value. The “predetermined value” is determined in advance based on experiments or the like, for example, at the required opening of the throttle valve that may cause an acceleration shock due to a change in the cylinder air amount. By doing in this way, the control apparatus of an internal combustion engine can restrict | limit the valve opening timing of a throttle valve appropriately only when it is necessary, and can suppress restrict | limiting unnecessary the valve opening timing of a throttle valve.

  In another aspect of the control apparatus for an internal combustion engine, the engine is an engine having a single cylinder or two cylinders. In general, the smaller the number of cylinders in the engine, the longer the time interval of the intake stroke, the longer the valve closing interval of the intake valve, and the more likely that acceleration shock will occur. In particular, in a single-cylinder or two-cylinder engine, the time width between the opening timing of the throttle valve and the closing timing of the intake valve may be long even at a normal rotation speed equal to or higher than the idle rotation speed. Therefore, when the engine is a single cylinder or two cylinders, the control device for the internal combustion engine preferably suppresses the acceleration shock caused by the excessive change in the in-cylinder air amount by limiting the opening timing of the throttle valve. be able to.

  In another aspect of the control apparatus for an internal combustion engine, the throttle valve opening timing limiting means performs control for limiting the valve opening timing when the engine rotation speed is less than a predetermined rotation speed. The “predetermined number of revolutions” is determined based on the number of cylinders and the like. For example, for each vehicle type, the number of engine revolutions at which there is no possibility of causing an acceleration shock due to a change in the in-cylinder air amount is determined in advance based on experiments or the like. By doing so, the control device for the internal combustion engine can restrict the opening timing of the throttle valve only when necessary, and can suppress unnecessary restriction of the opening timing of the throttle valve.

An example of schematic structure of an internal combustion engine is shown. An example of the graph of the throttle opening permission angle with respect to engine speed is shown. (A) shows the graph of the time change of the lift amount of the intake valve of a 1st cylinder, and the graph of the time change of the lift amount of an exhaust valve. (B) shows the graph of the time change of the lift amount of the intake valve of a 2nd cylinder, and the graph of the time change of the lift amount of an exhaust valve. It is an example of the flowchart which shows the process sequence in embodiment.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[Schematic configuration of internal combustion engine]
FIG. 1 is a schematic configuration diagram of an internal combustion engine (engine) to which a control device for an internal combustion engine according to the present invention is applied. A solid line arrow in the figure shows an example of a gas flow.

  The internal combustion engine 100 mainly includes an intake passage 1, a throttle valve 2, an exhaust passage 4, a first cylinder 10, and a second cylinder 20.

  Intake air (air) introduced from the outside passes through the intake passage 1, and the throttle valve 2 adjusts the flow rate of intake air passing through the intake passage 1. The opening of the throttle valve 2 is controlled by a control signal S2 supplied from the ECU 50 (hereinafter referred to as “throttle opening TA”).

  The intake air that has passed through the intake passage 1 is supplied to the combustion chamber 17 of the first cylinder 10 and the combustion chamber 27 of the second cylinder 20. The combustion chamber 17 is supplied with fuel injected by a fuel injection valve (injector) 15, and the combustion chamber 27 is supplied with fuel injected by a fuel injection valve 25. The fuel injection amounts of the fuel injection valves 15 and 25 are controlled based on control signals S15 and S25 transmitted from the ECU 50, respectively.

  Further, the combustion chamber 17 is provided with an intake valve 11 and an exhaust valve 13, and the combustion chamber 27 is provided with an intake valve 21 and an exhaust valve 23. The intake valve 11 is opened and closed to control the communication and blocking between the intake passage 1 and the combustion chamber 17, and the intake valve 21 is opened and closed to control the communication and blocking between the intake passage 1 and the combustion chamber 27. To do. The intake valve 11 is provided with an electromagnetic drive mechanism (so-called electromagnetic cam) 12, and the intake valve 21 is provided with an electromagnetic drive mechanism 22. The electromagnetic drive mechanisms 12 and 22 adjust the valve opening timing, valve closing timing, lift amount, and the like of the intake valves 11 and 21 based on the control signals S12 and S22, respectively. The exhaust valve 13 is opened and closed to control the communication and blocking between the combustion chamber 17 and the exhaust passage 4, and the exhaust valve 23 is opened and closed to control the communication and blocking between the combustion chamber 27 and the exhaust passage 4. To do.

  In the combustion chambers 17 and 27, the mixture of the intake air and the fuel supplied as described above in the intake stroke is burned in the expansion stroke by being ignited by the spark plugs 14 and 24, respectively, after passing through the compression stroke. . In this case, the pistons 18 and 28 reciprocate due to combustion, and the reciprocating motion is transmitted to the crankshaft (not shown) via the connecting rods 19 and 29, and the crankshaft rotates. Exhaust gas generated by combustion in the combustion chambers 17 and 27 is discharged to the exhaust passage 4 in the exhaust stroke.

  The accelerator opening sensor 30 detects an amount of depression of an accelerator pedal (not shown), that is, an accelerator opening. The accelerator opening sensor 30 supplies the detected value to the ECU 50 by a detection signal S30. The crank position sensor 31 detects the rotational position of the crankshaft. The crank position sensor 31 supplies the detection signal S31 to the ECU 50.

  The ECU 50 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and performs various controls on each component of the internal combustion engine 100. For example, the ECU 50 detects or estimates the pressure in the intake passage 1 when the intake valves 11 and 21 are open based on the detection values of various sensors, and refers to a predetermined map or the like to thereby determine the first cylinder 10 and The in-cylinder air amount of the second cylinder 20 is calculated. The ECU 50 calculates the in-cylinder air amount, the accelerator opening detected based on the accelerator opening sensor 31, the crank angle detected based on the crank position sensor 31 (hereinafter referred to as "crank angle CA"), and the engine rotation. The internal combustion engine 100 is controlled based on the number “Ne” or the like. The ECU 50 calculates the rotation position of the crankshaft detected by the crank position sensor 31 as an angle from a predetermined reference angle, and sets it as the crank angle CA. The ECU 50 functions as throttle valve control means and throttle valve opening timing control means in the present invention.

  The configuration in FIG. 1 is an example, and the configuration to which the present invention is applicable is not necessarily limited to this. For example, the internal combustion engine 100 is a port injection in which the fuel injection valves 15 and 25 are installed in the intake port, but instead of or in addition to this, a cylinder that directly injects fuel into the combustion chambers 17 and 27. Internal injection may be used. Further, the internal combustion engine 100 may be a self-ignition method that does not include the spark plugs 14 and 24.

[Control method]
Next, the control executed by the ECU 50 will be specifically described. Schematically, the ECU 50 opens the throttle valve 2 only when the crank angle CA is within a predetermined range. As a result, the ECU 50 suppresses an increase in the time span from the opening timing of the throttle valve 2 to the closing timing of the intake valves 11 and 21 (also referred to as “valve closing timing IVC”). Suppresses acceleration shock caused by air volume change.

  This will be specifically described. The ECU 50 changes the start timing for permitting the opening of the throttle valve 2 based on the engine speed Ne. Specifically, the ECU 50 sets a threshold value of the crank angle CA that permits the opening of the throttle valve 2 (also referred to as “throttle opening permission angle TAlim”) according to the engine speed Ne. Then, when the crank angle CA is more advanced than the throttle opening permission angle TAlim, the ECU 50 determines that the time from the opening timing of the throttle valve 2 to the closing timing IVC becomes longer, and the opening of the throttle valve 2 is increased. Do not allow valves. On the other hand, when the crank angle CA is equal to or retarded from the throttle opening permission angle TAlim, the ECU 50 determines that the time width from the opening timing of the throttle valve 2 to the closing timing IVC is within an allowable range where no acceleration shock occurs. The throttle valve 2 is allowed to open.

  Here, a method of setting the throttle opening permission angle TAlim will be described with reference to FIG. FIG. 2 shows a map (graph) of the throttle opening permission angle TAlim with respect to each engine speed Ne. The map shown in FIG. 2 is created based on an experiment or the like in advance so as to indicate the early value of the crank angle CA at which the acceleration shock due to the change in the in-cylinder air amount does not occur, and is stored in the memory of the ECU 50 in advance.

  As shown in FIG. 2, as the engine speed Ne is lower, the throttle opening permission angle TAlim is set to a retarded direction, that is, a direction closer to the crank angle CA at the valve closing timing IVC. In other words, as the engine speed Ne is lower, the range of the crank angle CA that permits the opening of the throttle valve 2 is set to be narrower. On the other hand, as the engine speed Ne is higher, the throttle opening permission angle TAlim is set in a direction of advance, that is, a direction away from the crank angle CA at the valve closing timing IVC. In other words, as the engine speed Ne is higher, the range of the crank angle CA that permits the opening of the throttle valve 2 is set wider.

  At a predetermined engine speed “Neth”, the throttle opening permission angle TAlim is set to a value that permits the opening of the throttle valve 2 with respect to an arbitrary crank angle CA. The engine speed Neth is determined in advance based on experiments and the like as a lower limit value of the engine speed at which there is no possibility of an acceleration shock due to a change in the in-cylinder air amount. As described above, the ECU 50 unnecessarily limits the opening timing of the throttle valve 2 when the engine speed Ne is equal to or higher than the engine speed Neth without the risk of acceleration shock due to the change in the cylinder air amount. prevent.

  Since the crank angle CA at which the first cylinder 10 becomes the intake stroke and the crank angle CA at which the second cylinder 20 becomes the intake stroke are different, the throttle opening permission angle TAlim is set to the first cylinder 10 and the second cylinder 20. Each is set to a different value depending on the phase difference. In this case, for example, the map referred to by the ECU 50 defines the throttle opening permission angles TAlim of the first cylinder 10 and the second cylinder 20 corresponding to each engine speed Ne.

  Here, the start timing of the opening permission of the throttle valve 2 will be specifically described for each of the first cylinder 10 and the second cylinder 20 with reference to FIGS. FIG. 3A shows a graph “IN1” of the time variation of the lift amount of the intake valve 11 of the first cylinder 10 and a graph “EX1” of the time variation of the lift amount of the exhaust valve 13. FIG. 3B shows a graph “IN2” of the time variation of the lift amount of the intake valve 21 of the second cylinder 20 and a graph “EX2” of the time variation of the lift amount of the exhaust valve 23. Here, times “Ts1” and “Ts2” in FIGS. 3A and 3B indicate times when the crank angle CA becomes the throttle opening permission angle TAlim, respectively.

  As shown in FIG. 3A, in the intake control of the first cylinder 10, the ECU 50 permits the opening of the throttle valve 2 from time Ts1 during the exhaust stroke when the crank angle CA becomes the throttle opening permission angle TAlim. Here, the time width “Y1” between the time Ts1 and the valve closing timing IVC is the valve opening timing of the throttle valve 2 at which there is no possibility of causing an acceleration shock due to a large change in the in-cylinder air amount of the first cylinder 10. This corresponds to the time width between the valve closing timing IVC and the valve closing timing IVC. Accordingly, in the intake control of the first cylinder 10, the ECU 50 opens the throttle valve 2 after the time Ts1, thereby suppressing the change in the in-cylinder air amount of the first cylinder 10 from being excessive, It is possible to suppress acceleration shock caused by a large change in the air amount.

  As shown in FIG. 3B, in the intake control of the second cylinder 20, the ECU 50 permits the opening of the throttle valve 2 from the time Ts2 during the exhaust stroke when the crank angle CA becomes the throttle opening permission angle TAlim. To do. Here, the width “Y2” between the time Ts2 and the valve closing timing IVC is the valve opening timing of the throttle valve 2 at which there is no possibility of causing an acceleration shock due to a large change in the in-cylinder air amount of the second cylinder 20. The time width with the valve closing timing IVC is shown. Accordingly, in the intake control of the second cylinder 20, the ECU 50 opens the throttle valve 2 after time Ts2, thereby suppressing the change in the in-cylinder air amount of the second cylinder 20 from becoming excessive. It is possible to suppress acceleration shock caused by a large change in the air amount.

  Preferably, the ECU 50 performs the above-described control when the required value of the throttle opening TA is equal to or greater than a predetermined value. Here, the above-mentioned “predetermined value” is determined in advance based on experiments or the like, for example, as a required value of the throttle opening TA that may cause an acceleration shock due to a change in the in-cylinder air amount. As a result, the ECU 50 can execute the above-described control only when there is a possibility that an acceleration shock may occur, and can suppress unnecessary restriction of the opening timing of the throttle valve 2.

(Processing flow)
FIG. 4 is a flowchart showing a processing procedure in the present embodiment. The flowchart shown in FIG. 4 is repeatedly executed by the ECU 50 according to a predetermined cycle.

  First, the ECU 50 determines whether or not the required value of the throttle opening degree TA is equal to or greater than a predetermined value (step S101). Then, when the required value of the throttle opening degree TA is equal to or larger than the predetermined value (step S101; Yes), the ECU 50 determines that there is a possibility that the change in the in-cylinder air amount is large, and advances the process to step S102. On the other hand, when the required value of the throttle opening degree TA is less than the predetermined value (step S101; No), the ECU 50 determines that the acceleration shock due to the in-cylinder air amount change does not occur and ends the process of the flowchart.

  Next, in step S102, the ECU 50 calculates a throttle opening permission angle TAlim from the engine speed Ne (step S102). For example, the ECU 50 refers to the map shown in FIG. 2 and calculates the throttle opening permission angle TAlim corresponding to the cylinder that is in the intake stroke from the engine speed Ne.

  Then, the ECU 50 determines whether or not the crank angle CA has reached the throttle opening permission angle TAlim (step S103). That is, the ECU 50 determines whether or not the crank angle CA is retarded from or equal to the throttle opening permission angle TAlim. If the ECU 50 determines that the crank angle CA has reached the throttle opening permission angle TAlim (step S103; Yes), the ECU 50 starts opening the throttle valve 2 based on the required value of the throttle opening TA (step S104). . That is, in this case, even if the throttle valve 2 is opened, the ECU 50 determines that the time width until the valve closing timing IVC is short enough to prevent acceleration shock, and opens the throttle valve 2.

  On the other hand, when it is determined that the crank angle CA has not reached the throttle opening permission angle TAlim (step S103; No), the ECU 50 continuously monitors the crank angle CA and waits until the crank angle CA reaches the throttle opening permission angle TAlim. (Step S103). Thereby, when the time width to the valve closing timing IVC is long and there is a possibility that an acceleration shock may occur, the opening timing of the throttle valve 2 can be delayed to suppress the acceleration shock.

[Modification]
In the description of FIG. 1 and the like, the internal combustion engine 100 has two cylinders. However, the configuration to which the present invention can be applied is not limited to this. For an internal combustion engine (engine) having a number of cylinders that may cause an acceleration shock due to an increase in the opening interval of the intake valves, etc. In addition, the present invention is preferably applied. For example, the present invention is preferably applied to a single cylinder engine. Specifically, even in the case of an internal combustion engine having a number of cylinders other than two, the ECU 50 permits the throttle opening based on the engine speed Ne when, for example, the required value of the throttle opening TA is equal to or greater than a predetermined value. After the angle TAlim is determined and the crank angle CA reaches the throttle opening permission angle TAlim, the throttle valve 2 is opened. Thereby, it is possible to suitably suppress the acceleration shock caused by the change in the in-cylinder air amount even for the internal combustion engine having the number of cylinders other than the two cylinders.

DESCRIPTION OF SYMBOLS 1 Intake passage 2 Throttle valve 4 Exhaust passage 10 1st cylinder 11, 21 Intake valve 12, 22 Electromagnetic drive mechanism 13, 23 Exhaust valve 17, 27 Combustion chamber 20 2nd cylinder 50 ECU

Claims (4)

Engine,
A throttle valve provided in the intake passage of the engine;
Throttle valve control means for controlling opening and closing of the throttle valve;
Throttle valve opening timing limiting means for performing control to limit the opening timing of the throttle valve by the throttle valve control means;
An internal combustion engine control device comprising:
The throttle valve opening timing limiting means is
The control apparatus for an internal combustion engine, wherein the start timing for allowing the throttle valve control means to open the throttle valve is set to a retard side as the engine speed is lower. The throttle valve opening timing limiting means is
2. The control device for an internal combustion engine according to claim 1, wherein when the required opening of the throttle valve is equal to or greater than a predetermined value, control for limiting the valve opening timing is performed.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the engine is an engine having a single cylinder or two cylinders. The throttle valve opening timing limiting means is
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein control for limiting the valve opening timing is performed when the engine speed is less than a predetermined speed.

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