JP4957590B2 - Control device for variable valve engine - Google Patents

Description

  The present invention relates to a control device for a variable valve engine, and more specifically, when variation occurs in intake air amount for each cylinder, this variation is eliminated while maintaining a good combustion state, and torque fluctuation is suppressed. Related to technology.

In a variable valve engine in which the valve timing of the intake valve is configured to be variable, when a variation occurs in the intake air amount for each cylinder, the lift amount of the intake valve is changed for the cylinder in which the variation has occurred. There is a technique for eliminating the variation in the intake air amount between the two (Patent Document 1).
JP2007-132187A (paragraph numbers 0004 to 0007)

  However, if there is a variation in the mechanical compression ratio for each cylinder in addition to the intake air amount, if the lift amount of the intake valve is simply changed with respect to the variation in the intake air amount, the actual compression ratio becomes too high. Therefore, there is a problem that knocking occurs or the actual compression ratio becomes too low, resulting in a decrease in thermal efficiency and an increase in fuel consumption.

  The present invention avoids deterioration of the combustion state such as knocking by controlling in consideration of the variation of the mechanical compression ratio for each cylinder in addition to the variation of the intake air amount when the variation of the intake air amount for each cylinder occurs. While aiming to eliminate variations.

  The present invention provides a control apparatus for a variable valve engine having a plurality of cylinders. In the present invention, a cylinder having a variation in intake air amount and mechanical compression ratio among the plurality of cylinders is specified, The variation amount of the intake air amount in the specified cylinder is calculated as the variation in intake air amount for each cylinder, and the variation amount of the mechanical compression ratio in this cylinder is calculated as the variation in mechanical compression ratio for each cylinder. Then, according to the variation of the calculated intake air amount and mechanical compression ratio for each cylinder, a control command for the variable valve operating device or the spark plug is output, and the valve timing of the intake valve in the specified cylinder is changed or by the spark plug Change the ignition timing.

  According to the present invention, the control command according to the variation in intake air amount by cylinder and the variation in mechanical compression ratio by cylinder is output, and the valve timing of the intake valve or the ignition timing by the spark plug is changed according to these variations. Therefore, it is possible to eliminate variations and avoid torque fluctuations while avoiding occurrence of knocking due to an excessively high actual compression ratio and a decrease in thermal efficiency due to an excessively low actual compression ratio.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows the configuration of a variable valve engine having a control device according to an embodiment of the present invention.

In this embodiment, the function as a control device for the variable valve engine is combined with the engine control unit 101 described later.
A main body (cylinder) of the engine 1 is configured by mounting a cylinder head 12 on a cylinder block 11 and fixing the cylinder head 12 to the cylinder block 11 with a head bolt (not shown). A piston 13 is inserted into the cylinder block 11 so as to reciprocate up and down, and a combustion chamber 14 is formed as a space sandwiched between the crown surface of the piston 13 and the lower surface of the cylinder head 12. In the cylinder head 12, ports (intake ports and exhaust ports) 15 and 16 for intake and exhaust are formed so as to communicate with the combustion chamber 14, and an intake valve 17 is connected to the intake port 15. 16, exhaust valves 18 are respectively installed. The intake valve 17 is urged in a closing direction by a valve spring (not shown) and is driven in an opening direction by an intake valve device 19 to open and close the intake port 15. The exhaust valve 18 is urged in the closing direction by a valve spring (not shown) and is driven in the opening direction by the exhaust valve device 20 to open and close the exhaust port 16. In the present embodiment, the valve timing of the intake valve 17 is made variable while the valve timing of the exhaust valve 18 is made constant so that the operating angle and lift amount of the intake valve 17 can be continuously changed as the intake valve operating device 19. By adopting a configured variable valve operating device (VEL: Continuous Variable Event and Lift), the closing timing of the intake valve 17 can be changed. In this embodiment, a variable mechanism (VCR: Variable Compression Ratio) for changing the mechanical compression ratio of the engine 1 is employed. FIG. 2 shows the configuration of this variable compression ratio mechanism. The variable compression ratio mechanism according to the present embodiment rotates the control shaft 26 by the actuator 25 and changes the position of the connecting portion c between the control shaft 26 and the first link 27, whereby the attitude of the second link 28 is changed. As a result, the position of the piston 13 at the top dead center changes, and the mechanical compression ratio of the engine 1 determined by the position of the piston 13 at the top dead center and the bottom dead center changes. In addition to the above, the fuel injection valve 21 is installed in the cylinder head 12 so that the injection hole is located in the intake port 15, and the spark plug 22 is located so that the plug gap is located in the approximate center of the upper part of the combustion chamber 14. Is installed.

  In the engine 1 having such a configuration, the air sucked through the air cleaner (not shown) together with the fuel injected into the intake port 15 by the fuel injection valve 21 passes through the intake port 15 during the opening period of the intake valve 17. Are introduced into the combustion chamber 14. The ignition plug 22 is activated at a predetermined time according to the operating state of the engine 1, and ignition is performed on the homogeneous air-fuel mixture formed in the combustion chamber 14 to cause combustion. Exhaust gas after combustion is discharged to the exhaust passage through the exhaust port 16 during the open period of the exhaust valve 18, purified by an exhaust processing device (not shown), and then released into the atmosphere.

  The operations of the intake valve device 19, the fuel injection valve 21 and the spark plug 22, and the actuator 25 of the variable compression ratio mechanism are engine control units (hereinafter referred to as “ECUs”) 101 configured as electronic control units including a microcomputer. Is controlled by a command signal from. The ECU 101 receives a signal from the accelerator sensor 151 for detecting an operation amount of the accelerator pedal by the driver (hereinafter referred to as “accelerator operation amount”) as a signal indicating an operation condition of the engine 1, and a crank angle sensor 152. In addition to a signal for each unit crank angle and reference crank angle, a signal from the temperature sensor 153 for detecting the temperature of the engine coolant, a signal from the pressure sensor 154 for detecting the in-cylinder pressure, and A signal from an angle sensor 155 for detecting the rotation angle of the control shaft 26 of the variable compression ratio mechanism is input. In the present embodiment, the in-cylinder pressure sensor 154 also functions as a knock level sensor.

Next, the operation of the ECU 101 according to the present embodiment will be described with reference to a flowchart.
FIG. 3 is a flowchart of a basic routine for engine control according to the present embodiment. This routine is executed at predetermined time intervals by the ECU 101 during normal operation after completion of startup.

In S101, the cylinder-specific intake air amount variation Uair is calculated according to the flowchart shown in FIG.
In S102, the cylinder-by-cylinder mechanical compression ratio variation Ucmp is calculated according to the flowchart shown in FIG.

  In S103, a control target is selected according to the flowchart shown in FIG. In the present embodiment, the operating angle of the intake valve 17 (hereinafter referred to as “intake operating angle”) θiv and the spark plug according to the combination of the sign of the variation in each cylinder of the intake air amount and the mechanical compression ratio calculated in S101 and 102. The control target is selected between the ignition timing Tig by 22 and the ignition timing Tig.

In S104, the correction control amount dθiv or dTig to be controlled is calculated according to the flowcharts shown in FIGS.
In S105, a control command corresponding to the correction control amount is output to the intake valve operating device 19 or the ignition plug 22, and the intake operation angle θiv or the ignition timing Tig is changed.

FIG. 4 is a flowchart of a cylinder-specific intake air amount variation calculation routine. By this routine, the cylinder-specific intake air amount variation Uair is calculated.
In S201, the accelerator operation amount APO is read as the operating state of the engine 1.

  In S202, the target intake air amount tQair per cylinder is calculated by dividing the target intake air amount corresponding to the read accelerator operation amount APO by the number of cylinders n (4 in this embodiment).

In S203, the intake operation angle θiv and the operation center angle CNT of the intake valve 17 are calculated based on the calculated target intake air amount Qair.
In S204, an actual intake air amount per cylinder (hereinafter referred to as “actual intake air amount by cylinder”) Qair is calculated based on the calculated intake operation angle θiv, operation center angle CNT, and engine speed NE. The calculation of the actual intake air amount Qair for each cylinder is performed in advance for each cylinder with the tendency shown in FIG. 5 reflecting the variation in the lift characteristics (or intake air amount) confirmed at the time of shipment from the cylinder. This is done by searching from the set map. In the map of FIG. 5, the cylinder specific actual intake air amount Qair is generally set to a larger value as the intake operation angle θiv is larger and as the operation center angle CNT is larger. The ECU 101 has a map of the cylinder-based actual intake air amount Qair for each engine speed NE, selects a map corresponding to the actual engine speed NE, and calculates the cylinder-specific actual intake air amount Qair. In the present embodiment, the actual intake air amount Qair for each cylinder is calculated by reflecting the variation of each cylinder confirmed in advance at the time of shipment from the factory, but the actual intake air amount Qair for each cylinder is actually detected by a sensor or the like. May be used.

  In S205, the cylinder specific intake air amount variation Uair (= tQair−Qair) is calculated by subtracting the cylinder specific actual intake air amount Qair from the target intake air amount tQair calculated as described above.

FIG. 6 is a flowchart of a cylinder-by-cylinder mechanical compression ratio variation calculation routine. By this routine, the cylinder-by-cylinder mechanical compression ratio variation Ucmp is calculated.
In S301, the accelerator operation amount APO and the engine speed NE are read as the operating state of the engine 1.

In S302, the target compression ratio tRcmp is calculated based on the read accelerator operation amount APO and engine speed NE.
In S303, an actual mechanical compression ratio of each cylinder (hereinafter referred to as "actual mechanical compression ratio for each cylinder") Rcmp is calculated based on the accelerator operation amount APO and the engine speed NE. The actual mechanical compression ratio Rcmp for each cylinder is calculated by calculating the rotation angle Asft of the control shaft 26 by searching from the map (FIG. 7) assigned in correspondence with the accelerator operation amount APO and the engine speed NE. The angle Asft is calculated by converting the mechanical compression ratio confirmed at the time of factory shipment or the like into the actual mechanical compression ratio Rcmp while reflecting the variation for each cylinder. FIG. 8 shows the relationship between the rotation angle Asft of the control shaft 26 and the mechanical compression ratio Rcmp. For conversion to the mechanical compression ratio Rcmp, table data (reflecting the variation of each cylinder) is shown for each cylinder. Created in advance and stored in the ECU 101. The actual mechanical compression ratio Rcmp for each cylinder is set to a small value in a low rotation high load region where the engine speed NE is low and the required torque (accelerator operation amount APO) for the engine 1 is high. If the variable compression ratio mechanism is not provided and the mechanical compression ratio is constant, the designed mechanical compression ratio is set as the target compression ratio tRcmp and the actual mechanical compression ratio Rcmp for each cylinder is set during production. Set the mechanical compression ratio obtained by actual measurement. When the cylinder-based actual mechanical compression ratio Rcmp varies depending on the operating state of the engine 1, the operating state of the engine 1 may be reflected in the calculation of the cylinder-based actual mechanical compression ratio Rcmp. In the present embodiment, the actual mechanical compression ratio Rcmp for each cylinder is calculated by reflecting the variation for each cylinder, which is confirmed in advance at the time of shipment from the factory, but the actual mechanical compression ratio Rcmp for each cylinder is actually detected by a sensor or the like. The mechanical compression ratio may be used.

  In S304, the cylinder-by-cylinder mechanical compression ratio variation Ucmp (= tRcmp−Rcmp) is calculated by subtracting the cylinder-by-cylinder actual mechanical compression ratio Rcmp from the target compression ratio tRcmp calculated as described above.

  FIG. 9 is a flowchart of the control target selection routine. By this routine, the control target is switched between the operating angle (intake operating angle) θiv of the intake valve 17 and the ignition timing Tig by the spark plug 22.

In S401, a variable i indicating a cylinder number is set to 1.
In S402, the intake air amount variation Uair for each cylinder of the i-th cylinder is read.
In S403, the cylinder-by-cylinder mechanical compression ratio variation Ucmp of the i-th cylinder is read.

  In S404, it is determined whether or not the signs of the intake air amount of the i-th cylinder and the mechanical variation ratios Uair and Ucmp for each cylinder match. If they match, the process proceeds to S405, and if they do not match, the process proceeds to S406.

In S405, the valve timing (intake operation angle θiv) of the intake valve 17 is selected as the control target, and the control target determination flag F is set to 1.
In S406, the ignition timing Tig by the spark plug 22 is selected as the control target, and the control target determination flag F is set to 2.

In S407, it is determined whether or not the variable i has reached the number of cylinders n (= 4). If n has been reached, the routine is returned. If not, the process proceeds to S408.
In S408, 1 is added to the variable i, the process returns to S402, and the processes of S402 to 407 are repeated.

  FIG. 10 is a flowchart of a correction control amount calculation routine. The correction control amount dθiv or dTig to be controlled is calculated by this routine, an intake operating angle correction routine and an ignition timing correction routine which will be described later.

In S501, a variable i indicating a cylinder number is set to 1.
In S502, it is determined whether or not the control target determination flag F is 1. When it is 1, it progresses to S503, and when it is not 1, it progresses to S504.

In S503, the intake operating angle θiv of the i-th cylinder is corrected according to the flowchart shown in FIG.
In S504, it is determined whether or not the control target determination flag F is 2. If it is 2, the process proceeds to S505. If it is not 2, the process proceeds to S506.

In S505, the ignition timing Tig of the i-th cylinder is corrected according to the flowchart shown in FIG.
In S506, it is determined whether or not the variable i has reached the number of cylinders n. If n has been reached, the routine returns. If not, the process proceeds to S507.

In S507, 1 is added to the variable i, the process returns to S502, and the processes in S502 to S506 are repeated.
FIG. 11 is a flowchart of an intake operating angle correction routine. In this embodiment, this routine is executed as a subroutine of a correction control amount calculation routine (S503) shown in FIG.

In S601, the intake operation angle θiv is read.
In S602, based on the read intake operation angle θiv, a correction amount of the intake operation angle θiv (hereinafter referred to as “operation angle correction amount”) that can correct the actual compression ratio of the cylinder by the cylinder-specific mechanical compression ratio variation Ucmp of the cylinder i. ) Dθiv is calculated. If the intake operating angle θiv is converted into the closing timing IVC of the intake valve 17, the corrected closing timing IVC2 is the corrected closing timing IVC1, the cylinder-specific mechanical compression ratio variation Ucmp, the volume Vf of the combustion chamber 14, and the cylinder bore It can be calculated by the following equation (1) based on the inner diameter φc. The ECU 101 calculates an operating angle correction amount dθiv for setting the closing timing of the intake valve 17 to IVC2. In the following equation (1), f (IVC) is a function of the piston position with respect to the closing timing IVC of the intake valve 17.

f (IVC2) = f (IVC1) + Vf × Ucmp / (π × (φc / 2) ² ) (1)
In S <b> 603, the intake operating angle θiv is corrected by adding the calculated operating angle correction amount dθiv to the intake operating angle θiv, and the valve timing of the intake valve 17 is changed.

θiv = θiv + dθiv (2)
FIG. 12 is a flowchart of an ignition timing correction routine. In this embodiment, this routine is executed as a subroutine of a correction control amount calculation routine (S505) shown in FIG.

In S701, the knock level Lknc of the i-th cylinder is read. Knock level Lknc can be calculated based on the output from in-cylinder pressure sensor 154.
In S702, it is determined whether or not the read knock level Lknc is equal to or greater than a predetermined value L1. When it is equal to or greater than the predetermined value L, the process proceeds to S703, and when it is smaller than the predetermined value L1, the process proceeds to S704.

In S703, the ignition timing Tig is retarded by a predetermined value ΔT.
In S704, it is determined whether the knock level Lknc is smaller than a predetermined value L1. When it is smaller than the predetermined value L1, the process proceeds to S705, and when it is equal to or larger than the predetermined value L1, this routine is returned.

In S705, the ignition timing Tig is advanced by a predetermined value ΔT.
In the present embodiment, the function as “cylinder specifying means” is performed by the processing of the entire flowchart shown in FIG. 4 and the processing of S402 of the flowchart shown in FIG. 9 by the processing of S401, 407, and 408 of the flowchart shown in FIG. The function as the “intake air amount variation calculating means” is the function of the “mechanical compression ratio variation calculating means” by the processing of the entire flowchart shown in FIG. 6 and the processing of S403 of the flowchart shown in FIG. The function as “control command output means” is realized by the processing of S404 to S406, and the function as “knock level detection means” is realized by the processing of S701 in the flowchart shown in FIG.

According to this embodiment, the following effects can be obtained.
In this embodiment, when variation occurs in the intake air amount for each cylinder, the intake air amount variation Uair for each cylinder and the mechanical compression ratio variation Ucmp for each cylinder are calculated, and the sign of the calculated variation for each cylinder (positive, negative) ), The valve timing (intake operating angle θiv) of the intake valve 17 or the ignition timing Tig by the spark plug 22 is changed. Compared to the case where only the variation in the intake air amount is taken into consideration. Thus, it is possible to eliminate the variation while avoiding the occurrence of knocking due to the actual compression ratio becoming too high, and the decrease in thermal efficiency due to the actual compression ratio becoming too low.

  15 to 18 are time charts showing the operation of the ECU 101 that executes the engine control according to the present embodiment. In each figure, a solid line A indicates a cylinder in which the intake air amount and the mechanical compression ratio vary, and a two-dot chain line B indicates that these variations do not occur or a variation that occurs more than the cylinder indicated by the solid line A. The other cylinders are small.

  FIG. 15 shows the case where the cylinder-specific intake air amount variation Uair and the cylinder-specific mechanical compression ratio variation Ucmp are both negative. In this case, the intake operating angle θiv is selected as a control target, and the closing timing of the intake valve 17 is advanced (or the intake operating angle θiv is decreased), thereby suppressing knocking and reducing torque fluctuation. it can.

  FIG. 16 shows a case where the intake air amount variation Uair for each cylinder and the mechanical compression ratio variation Ucmp for each cylinder are both positive. In this case, by increasing the intake operating angle θiv as a control target and retarding the closing timing of the intake valve 17, the variation can be eliminated and the thermal efficiency can be improved.

  FIG. 17 shows the case where the cylinder-specific intake air amount variation Uair is positive and the cylinder-specific mechanical compression ratio variation Ucmp is negative. In this case, the ignition timing Tig by the spark plug 22 is selected as a control target so that the knock level Lknc becomes a low knock level (in other words, a trace knock state), and according to the knock level Lknc. By changing the ignition timing Tig, torque fluctuation can be suppressed while avoiding the deterioration of knocking. In FIG. 17, a dotted line C shows a comparative example in which the variation in intake air amount is attempted to be eliminated by changing the valve timing of the intake valve 17. In this comparative example, knocking is worsened due to an excessive increase in the actual compression ratio accompanying the increase in the intake air amount (time t1), and torque fluctuations are increased due to the retard of the ignition timing for suppressing this knocking. Yes.

  FIG. 18 shows the case where the cylinder-specific intake air amount variation Uair is negative and the cylinder-specific mechanical compression ratio variation Ucmp is positive. Also in this case, it is possible to improve the thermal efficiency by selecting the ignition timing Tig by the spark plug 22 as a control target and changing the ignition timing Tig according to the knock level Lknc so as to be in the state of trace knock. it can. If the variation in the intake air amount is to be eliminated by changing the valve timing of the intake valve 17 (dotted line C), the thermal efficiency is lowered due to the excessive decrease in the actual compression ratio accompanying the decrease in the intake air amount, and the fuel Increases consumption.

Hereinafter, other embodiments of the present invention will be described.
FIG. 13 is a flowchart of a cylinder-by-cylinder variation adjustment routine according to the second embodiment of the present invention. The engine control according to the present embodiment can be performed according to the basic routine shown in FIG. 3, and the control object selection routine according to the present embodiment is made up of the cylinder-by-cylinder variation adjustment routine shown in FIG. 13 and the routine shown in FIG. Constitute.

In S801, the accelerator operation amount APO and the engine speed NE are read as the operating state of the engine 1.
In S802, the area (the low compression ratio reference area A or the high compression ratio reference area B) to which the operating state of the engine 1 belongs is determined by referring to the map shown in FIG. 14 based on the read accelerator operation amount APO or the like. When belonging to the low compression ratio reference area A, the process proceeds to S803, and when belonging to the high compression ratio reference area B, the process proceeds to S804.

In S803, the x-th cylinder having the smallest cylinder-by-cylinder mechanical compression ratio variation Ucmp is specified as the reference cylinder.
In S804, the x-th cylinder having the largest cylinder-by-cylinder mechanical compression ratio variation Ucmp is specified as the reference cylinder.

In S805, the variable i indicating the cylinder number is set to 1.
In S806, the intake air amount variation Uair (i) for each cylinder of the i-th cylinder is read.
In S807, the cylinder-by-cylinder mechanical compression ratio variation Ucmp (i) of the i-th cylinder is read.

  In S808, the cylinder-specific variation U (x) of the x-th cylinder is subtracted from the cylinder-specific variation U (i) of the i-th cylinder, and the value after subtraction is newly set to U (i). The cylinder-specific variation U (i) is converted into a cylinder-specific variation based on the x-th cylinder.

Uair (i) = Uair (i) −Uair (x) (3a)
Ucmp (i) = Ucmp (i) −Ucmp (x) (3b)
In S809, it is determined whether or not the variable i has reached the number of cylinders n (4 in the present embodiment). If n has been reached, the routine is returned. If not, the process proceeds to S810.

In S810, 1 is added to the variable i, the process returns to S806, and the processes of S806 to 809 are repeated.
Thereafter, a control target is selected according to the flowcharts shown in FIGS. 9 to 12 based on the converted intake air amount variation Uair for each cylinder Uair and mechanical compression ratio variation Ucmp for each cylinder, and a corrected control amount is calculated.

  In the present embodiment, the function as “reference cylinder selection means” is performed by the processing of S806 and 808 of the flowchart shown in FIG. 13 and the entire processing of the flowchart shown in FIG. 4 by the processing of S802 to 804 of the flowchart shown in FIG. The function as the “intake air amount variation calculating means” is realized as the “mechanical compression ratio variation calculating means” by the processes of S807 and 808 in the flowchart shown in FIG. 13 and the entire flowchart shown in FIG.

  According to the present embodiment, in addition to the above-described effects obtained by the first embodiment, a cylinder in a low-rotation high-load side region (corresponding to a “first region”) that tends to cause knocking. By using the cylinder having the smallest mechanical compression ratio variation Ucmp as a reference, the actual compression ratio of the cylinder in which the variation has occurred can be reduced, and knocking can be reliably avoided. Further, in the other region (corresponding to the “second region”), the cylinder with the largest variation in mechanical compression ratio by cylinder Ucmp is used as a reference to increase the actual compression ratio of the cylinder in which the variation has occurred. , Can improve the thermal efficiency.

  Note that, in the high compression ratio reference region B, the torque fluctuation is suppressed by retarding the ignition timing for the cylinder in which the intake air amount is increased by changing the valve timing and the actual compression ratio is excessively increased.

Configuration of a variable valve engine according to a first embodiment of the present invention Configuration of variable compression ratio mechanism provided in variable valve engine according to the embodiment Flow chart of basic routine for engine control Flow chart of intake air amount variation calculation routine for each cylinder Relationship between the operating state of the variable valve system (intake operation angle, operation center angle) and intake air volume Flowchart of cylinder-specific mechanical compression ratio variation calculation routine Relationship between engine operating state (accelerator operation amount, engine speed) and control shaft rotation angle Relationship between rotation angle of control shaft and mechanical compression ratio Control target selection routine flowchart Flow chart of correction control amount calculation routine Flow chart of operating angle correction amount calculation routine Flowchart of ignition timing correction amount calculation routine Flow chart of variation adjustment routine for each cylinder Calculation map for specifying the reference cylinder Time chart showing the contents of control when the variation in intake air amount by cylinder and the variation in mechanical compression ratio by cylinder are both negative Time chart showing the contents of control when both the variation in intake air amount by cylinder and the variation in mechanical compression ratio by cylinder are both positive Time chart showing details of control when variation in intake air amount by cylinder is positive and variation in mechanical compression ratio by cylinder is negative Time chart showing details of control when variation in intake air amount by cylinder is negative and variation in mechanical compression ratio by cylinder is positive

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Variable valve engine (engine), 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Piston, 14 ... Combustion chamber, 15 ... Intake port, 16 ... Exhaust port, 17 ... Intake valve, 18 ... Exhaust valve, 19 DESCRIPTION OF SYMBOLS ... Intake valve device, 20 ... Exhaust valve device, 21 ... Fuel injection valve, 22 ... Spark plug, 101 ... Engine control unit, 151 ... Accelerator sensor, 152 ... Crank angle sensor, 153 ... Cooling water temperature sensor, 154 ... In-cylinder pressure sensor, 155 ... control shaft rotation angle sensor, 25 ... actuator, 26 ... control shaft, 27 ... first link, 28 ... second link.

Claims (10)

A control device for a variable valve engine having a plurality of cylinders,
Cylinder specifying means for specifying cylinders that vary with respect to the intake air amount and the mechanical compression ratio among the plurality of cylinders;
Intake air amount variation calculating means for calculating the variation amount of the intake air amount in the cylinder specified by the cylinder specifying means as the intake air amount variation for each cylinder;
Mechanical compression ratio variation calculating means for calculating the variation amount of the mechanical compression ratio in the specified cylinder as the cylinder-specific mechanical compression ratio variation;
The valve timing of the intake valve or the ignition timing by the ignition plug in the specified cylinder is changed according to the variation in each intake air amount and mechanical compression ratio calculated by the intake air amount variation calculating means and the mechanical compression ratio variation calculating means. And a control command output means for outputting a control command for controlling the variable valve engine.   The control command output means changes the valve timing of the intake valve in the specified cylinder or the ignition timing by the ignition plug according to the combination of the calculated variation in intake air amount by cylinder and variation in mechanical compression ratio by cylinder The control apparatus for a variable valve engine according to claim 1, wherein a control command for changing the engine is selectively output.   The control command output means, when the intake air amount varies on the side where the intake air amount is large or when the variation of the intake air amount and the mechanical compression ratio for each cylinder is positive, The variation according to claim 2, wherein when the calculated variation in intake air amount by cylinder and variation in mechanical compression ratio by cylinder coincide with each other, the variation is reduced by changing the valve timing of the intake valve in the specified cylinder. Control device for variable valve engine.   The control command output means, when the intake air amount varies on the side where the intake air amount is large or when the variation of the intake air amount and the mechanical compression ratio for each cylinder is positive, 4. The control device according to claim 2, wherein when the calculated variation in the intake air amount by cylinder and the variation in the mechanical compression ratio by cylinder are different, these variations are reduced by changing the ignition timing in the specified cylinder. Control device for variable valve engine.   The control command output means includes knock level detection means for detecting a knock level indicating the magnitude of knocking, and the intake air amount when the intake air amount varies toward the side with a large intake air amount or when the mechanical compression ratio varies with the side And when the sign of the variation in each cylinder of the mechanical compression ratio is positive, the ignition timing in the specified cylinder is different when the sign of the calculated intake air amount variation by cylinder and the sign of the variation in mechanical compression ratio by cylinder are different. The control device for a variable valve engine according to claim 2 or 3, wherein the angle is advanced or retarded according to a knock level detected by the knock level detecting means. Reference cylinder specifying means for specifying, as a reference cylinder, a cylinder corresponding to the operating state of the engine, which is used as a reference for the valve timing of the intake valve or the ignition timing by the ignition plug,
The intake air amount variation calculating means calculates the intake air amount variation for each cylinder as a variation amount of the intake air amount of the specified cylinder with respect to the reference cylinder specified by the reference cylinder specifying means,
The mechanical compression ratio variation calculating means calculates the cylinder-specific mechanical compression ratio variation as a variation amount of the mechanical compression ratio of the specified cylinder with respect to the reference cylinder specified by the reference cylinder specifying means. A control apparatus for a variable valve engine according to claim 1.   The reference cylinder specifying unit specifies, as the reference cylinder, a cylinder having the smallest variation in mechanical compression ratio for each cylinder when the engine operating state is in a first region set in advance as a region on the low rotation high load side. On the other hand, when the operating state of the engine is in a second region preset as a region other than the first region, a cylinder having the largest variation in mechanical compression ratio by cylinder is specified as the reference cylinder. The control apparatus of the variable valve engine described.   The intake air amount variation calculating means calculates the intake air amount variation for each cylinder as a variation amount of the actual intake air amount of the engine with respect to the target intake air amount, and calculates the actual intake air amount as an intake valve. The control apparatus for a variable valve engine according to any one of claims 1 to 7, wherein calculation is performed as a preset value corresponding to the operating state of the variable valve apparatus for changing the valve timing and the operating state of the engine. .   The mechanical compression ratio variation calculating means calculates the mechanical compression ratio variation for each cylinder as an amount of variation of the actual mechanical compression ratio of the engine with respect to the target mechanical compression ratio. The calculation according to any one of claims 1 to 8, wherein the calculation is performed as a preset value corresponding to the operating state or the actual mechanical compression ratio is detected based on an output from a compression ratio sensor disposed so as to be detectable. Variable valve engine control device. Among the multiple cylinders, identify cylinders that vary in terms of intake air volume and mechanical compression ratio,
The variation of the intake air amount in the specified cylinder with respect to the reference intake air amount is calculated as the variation in intake air amount by cylinder,
The variation of the mechanical compression ratio in the specified cylinder with respect to the reference mechanical compression ratio is calculated as the variation in cylinder-specific mechanical compression ratio,
Depending on the combination of the calculated intake air amount and the sign of the variation for each cylinder of the mechanical compression ratio, the valve timing of the intake valve in the specified cylinder is changed to reduce the variation, or the knock level is a predetermined low knock level A control method for a variable valve engine that changes the ignition timing in a specified cylinder so as to maintain the engine.

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