JP4899878B2 - Combustion control device for internal combustion engine - Google Patents

Description

  The present invention relates to a combustion control device for an internal combustion engine, and more particularly to a combustion control device for an internal combustion engine that is suitable for suppressing the occurrence of knocking in an internal combustion engine having a variable compression ratio mechanism.

  Conventionally, a control device for an internal combustion engine has been proposed that includes a variable compression ratio mechanism and a variable valve mechanism to prevent knocking without retarding the ignition timing (see Patent Document 1).

This is to obtain a target intake air amount and a target compression ratio in accordance with the operating state during transient operation that shifts from the high compression ratio setting to the low compression ratio setting operation condition, and to control the variable compression ratio mechanism according to the target compression ratio. At that time, the knock limit intake air amount is obtained from the actual compression ratio realized by the variable compression ratio mechanism, and the smaller of the knock limit intake air amount and the target intake air amount is set as the final target intake air amount. By controlling the variable valve mechanism, the occurrence of knocking is prevented without retarding the ignition timing, that is, without causing deterioration in fuel consumption.
JP 2005-127212 A

  However, in the above conventional example, the intake air amount is reduced because the smaller one of the knock limit intake air amount and the target intake air amount is used as the final target intake air amount to reduce the intake air amount and avoid knocking. That is, acceleration failure occurs with a decrease in torque.

  That is, if the compression ratio at the knocking limit is set in the steady condition before acceleration, the intake air amount cannot be increased until the actual compression ratio changes even if there is an acceleration request. In other words, the variable compression ratio mechanism improves fuel consumption because the compression ratio cannot be set so that the intake air amount becomes the knock limit intake air amount in steady conditions before acceleration so that knocking does not occur even if a sudden acceleration request occurs. The effect cannot be obtained sufficiently.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a combustion control device for an internal combustion engine that is suitable for suppressing knocking even when the actual compression ratio is higher than the target compression ratio.

The present invention relates to a variable compression ratio mechanism for changing the effective compression ratio, a target compression ratio calculation means for obtaining a target effective compression ratio from operating conditions, and a means for detecting an actual effective compression ratio realized by the variable compression ratio mechanism. A water spray mechanism capable of spraying water into the combustion chamber according to engine operating conditions, and a control for operating the water spray mechanism when a difference between the actual effective compression ratio and the target effective compression ratio is higher than a preset value Means for correcting the set value to be low when the load of the internal combustion engine is relatively high, when the rotational speed of the internal combustion engine is relatively low, or when the cooling water temperature of the internal combustion engine is relatively high. I made it.

Therefore, in the present invention, in transient operation, when the difference between the actual compression ratio and the target compression ratio is higher than a preset set value, the unburned mixture temperature is lowered by water spray, the intake amount is limited, and the acceleration is poor. Or delaying the ignition timing and causing no deterioration in fuel consumption, knocking can be suppressed and the knock limit compression ratio can be set in a steady state. Can get as much as possible.
In addition, knocking occurs because the set value is corrected to be low when the load on the internal combustion engine is relatively high, the rotational speed of the internal combustion engine is relatively low, or the cooling water temperature of the internal combustion engine is relatively high. It is possible to promote the execution of water spray when the operating conditions are easy to perform, and to effectively prevent the occurrence of knocking.

  Hereinafter, a combustion control device for an internal combustion engine of the present invention will be described based on each embodiment.

(First embodiment)
1 to 13 show a first embodiment of a combustion control device for an internal combustion engine to which the present invention is applied, FIG. 1 is a system configuration diagram of the combustion control device for the internal combustion engine, and FIG. 2 is a variable compression ratio of the combustion control device. FIG. 3 is a side view of the variable compression ratio mechanism, FIG. 4 is a sectional view of a combustion chamber in a combustion control device of an internal combustion engine, FIG. 5 is an explanatory diagram of a water spray pattern, and FIG. It is a figure which shows the map of compression ratio. As shown in FIG. 1, the combustion control apparatus for an internal combustion engine according to this embodiment includes a variable compression ratio mechanism A capable of changing an effective compression ratio of an internal combustion engine having a reciprocating piston, and a combustion chamber of the internal combustion engine. A water spray mechanism B capable of spraying water.

  The variable compression ratio mechanism A includes an upper link 5 and a lower link 5 connected to a piston 3 and a crank pin 8 of a crankshaft 7 which are disposed in a plurality of cylinders 2 formed along a cylinder row of the cylinder block 1 so as to be movable up and down. A multi-link mechanism D configured to be mechanically linked by a link 6 is provided. Specifically, one end of the upper link 5 is rotatably connected to the piston pin 4 of each piston 3, and the other end of the upper link 5 and the lower link 6 are rotatably connected to each other via the first connection pin 9. The lower link 6 is rotatably connected to the crank pin 8. The crankshaft 7 is provided with a counterweight 7A.

  One end of a control link 11 is rotatably connected to each lower link 6 via a second connecting pin 10, and the other end of the control link 11 is rotated to the cylinder block 1 as shown in FIG. It is fitted to an eccentric cam portion 12A of a control shaft 12 (control shaft) that can be provided, and is supported so as to be swingable around the eccentric cam portion 12A. The connecting positions of the crank pin 8, the first connecting pin 9, and the second connecting pin 10 connected to the lower link 6 are not arranged on the same straight line but are arranged in a substantially triangular shape.

  The eccentric cam portion 12 </ b> A of the control shaft 12 (control shaft) that is the swing center of the control link 11 can variably control the support position by controlling the rotational angle position of the control shaft 12. As shown in FIG. 3, the control shaft 12 is arranged in parallel with the crankshaft 7, and on the cylinder block 1 side via a bearing portion 12 </ b> B arranged in the cylinder block 1 corresponding to each journal position of the crankshaft 7. The bearing hole 15 is rotatably supported. The bearing hole 15 is formed by a bulkhead 14 and a bearing cap 13 formed in the cylinder block 1. A worm wheel 16 is coupled to the control shaft 12, and a rotational angle position of the control shaft 12 is controlled by rotationally driving a worm gear 17 meshing with the worm wheel 16 by an actuator motor 18.

  As shown in FIG. 4, the water spray mechanism B includes water spray valves 22 provided on the cylinder head 21 such that spray ports face the combustion chamber 20 from above the combustion chambers 20 of the internal combustion engine, Water supply means 23 for supplying water to the water spray valve 22 is provided. Each water spray valve 22 is configured to spray water directly into the combustion chamber 20 from above. Spraying is performed in the form shown in FIG. 5A by hollow cone (hollow conical) spraying from one spraying port toward the peripheral edge of the crown surface of the piston 3 and the wall surface side of the cylinder 2. It can be in the form of a cone shown, or a multi-hole spray shown in FIG. 5C or FIG. 5D by spraying from a plurality of spray ports. 5 (A) and FIG. 5 (B), when the centrifugal action is large due to the degree of centrifugal force action by the spraying fluid swirling means (not shown) built in the water spray valve 22, FIG. When the centrifugal action is relatively small, the density is high in the peripheral portion and the density decreases as it reaches the central portion. Note that an intake port 27A is connected to the combustion chamber 20 via an intake valve 27, an exhaust port is connected via an exhaust valve 28, and an ignition plug 29 is disposed.

  As shown in FIG. 1, the water supply means 23 includes a water tank 24 for storing water, a pump 25 for sucking water from the water tank 24 and discharging it at high pressure, and a high-pressure tank for accumulating high-pressure water discharged from the pump. 26, and water stored in the high-pressure tank 26 is supplied to each water spray valve 22. The pump 25 is operated each time the amount of high-pressure water stored in the high-pressure tank 26 becomes less than a predetermined amount, and is controlled so that a predetermined amount or more of high-pressure water is always stored in the high-pressure tank 26.

  The actuator motor 18 and the water spray valve 22 of the variable compression ratio mechanism A are respectively controlled by a rotation angle position command and a spray command from the engine controller ECU 30. The rotational angle position of the actuator motor 18 is detected by a built-in motor encoder (not shown) and fed back to the engine controller ECU 30. The engine controller ECU 30 receives signals such as the engine speed, the engine load, the intake negative pressure, the exhaust temperature, the coolant temperature, the intake air temperature, and a knock signal. The engine controller ECU 30 determines the operating state of the engine based on these input signals, calculates the target compression ratio of the engine according to the operating state, and rotates the actuator motor 18 so as to obtain the target compression ratio obtained by the calculation. Outputs angular position command.

  The target compression ratio of the engine according to the operating state is calculated based on the target compression ratio map. As shown in FIG. 6, the target compression ratio map is defined by engine torque (engine load) and engine speed, and a high compression ratio (CR = High) is set in a region where the engine torque (load) is low. The setting is changed to the intermediate compression ratio (CR = Medium) according to the increase of the engine torque (load), and is set to the low compression ratio (CR = Low) in a region where the engine torque (load) further increases. These high compression ratio / intermediate compression ratio / low compression ratio setting areas are gradually expanded to increase engine torque (load) as the engine speed increases. Each region of the intermediate compression ratio and the low compression ratio is also set so that the engine torque gradually increases as the engine speed increases.

  Further, a difference dCR between an actual rotation angle position signal (actual compression ratio of a variable compression ratio mechanism described later) from the motor encoder and a target angle position command (target compression ratio command output output to the variable compression ratio mechanism) is calculated. When the difference dCR exceeds a predetermined value set in advance, it is determined that the operation state is likely to cause knocking, and a water spray command for executing water spray from the water spray valve 22 is output.

  As shown in FIG. 7, the spray amount of the water spray at this time is made small when the difference dCR is relatively small, and gradually increases as the difference dCR increases according to the difference dCR. Thus, the amount of water spray is increased as knocking is more likely to occur, so that both saving of the amount of water spray and effective suppression of knocking can be achieved.

  As shown in FIG. 8, the spray amount of the water spray is corrected to increase in accordance with the engine load, and the occurrence of knocking in a high-load operation state in which knocking is likely to occur can be further suppressed. . Further, as shown in FIG. 9, the occurrence of knocking can be further suppressed by correcting the increase in a region where the engine speed is low and is easy to knock. Furthermore, as shown in FIG. 10, the occurrence of knocking in a high-temperature operation state can be further suppressed by correcting the increase according to the increase in the coolant temperature that is likely to induce knocking.

  In addition, the engine controller ECU 30 calculates an ignition timing according to the operating state of the engine, and outputs a command to the ignition timing control device 31 so as to achieve the calculated ignition timing. This ignition timing is likely to cause knocking when the difference dCR between the actual rotation angle position signal of the actuator motor 18 and the target angle position command exceeds a predetermined value and the actual compression ratio is higher than the target compression ratio. Although it is determined to be in the operating state and is corrected to the retard side, the water spray by the water spray mechanism B is executed and the air-fuel mixture in the combustion chamber 20 and / or the crown surface of the piston 3 constituting the wall surface of the combustion chamber 20 Since the occurrence of knocking is suppressed by cooling the outer peripheral side of the cylinder and the wall surface of the cylinder 2, the retard correction amount of the ignition timing can be reduced by that amount, thereby suppressing a decrease in thermal efficiency and suppressing deterioration in fuel consumption. it can.

  FIG. 11 is a flowchart showing a water spray control routine that is executed every predetermined time by the engine controller ECU 30 of the combustion control device for an internal combustion engine according to the present embodiment. Below, it demonstrates based on the flowchart of FIG.

  In step S1, first, signals such as engine speed, engine load, intake negative pressure, exhaust temperature, cooling water temperature, intake air temperature, knock signal and the like are read.

  Next, in step S2, the target compression ratio in the current engine operating state is calculated based on the target compression ratio map shown in FIG. 6 with reference to the target compression ratio map.

  In step S3, a target compression ratio command (actuator motor rotation angle position command) that is a target compression ratio corresponding to the calculated engine operating state is output to the actuator motor 18 of the variable compression ratio mechanism A. As a result, the actuator motor 18 is rotationally driven to a new target angular position. The rotation of the actuator motor 18 rotates the control shaft 12 via the worm gear 17 and the worm wheel 16 to change the swing angle position of the eccentric cam portion 12A, and the swing fulcrum position of the control link 11 to be changed. The piston top dead center position is changed to a new target value via the link 6 and the upper link 5. However, the operation of the variable compression ratio mechanism A is gradually changed with a load reaction force due to the combustion gas pressure and a response delay due to the inertial force and friction of the multi-link mechanism D.

  In step S4, the actual compression ratio of the variable compression ratio mechanism A is read based on the output signal from the motor encoder built in the actuator motor 18. As described above, this actual compression ratio has a response delay with respect to the command signal.

  In step S5, a difference dCR between the target compression ratio in step S3 and the actual compression ratio is calculated. This difference dCR becomes large when the speed of change of the target compression ratio is large.

  In step S6, it is determined whether or not the difference dCR calculated in step S5 exceeds an allowable predetermined value set in advance. If the difference dCR exceeds the allowable predetermined value, the process proceeds to step S7 and is allowed. If it is within the set value range, the current processing step is terminated. The allowable set value can be changed according to the operating state of the engine. For example, when the engine load is relatively high, when the engine speed is relatively low, or when the cooling water temperature is relatively high, the execution of water spray can be promoted by correcting the set value low, The knocking tendency can be effectively suppressed.

  In step S7, since the occurrence of knocking is expected due to the difference dCR exceeding a predetermined allowable value set in advance, a water spray command is output, and the current process ends. When the water spray command is output, the water spray valve 22 is opened, and the water supplied from the water supply means 23 is sprayed into the combustion chamber 20. As shown in FIG. 7, the spray amount of the water spray at this time is made small when the difference dCR is relatively small, and gradually increases as the difference dCR increases according to the difference dCR. Thus, the amount of water spray is increased as knocking is more likely to occur, so that both saving of the amount of water spray and effective suppression of knocking can be achieved.

  Since the timing of the water spray is started after the intake valve 27 is closed in the combustion cycle, the intake air amount is not affected. As shown in FIG. 13, when sprayed immediately after the intake valve 27 is closed, the vaporization time from water spraying through the compression stroke to ignition / combustion can be maximized. For this reason, the whole combustion chamber 20 can be cooled. The water spray valve 22 shown in FIG. 13 differs from the water spray valve 22 shown in FIG. 4 in the arrangement in the combustion chamber 20 so that the spray port opens near the upper end of the wall surface of the cylinder 2 of the combustion chamber 20. Has been placed. Even in this case, water can be sprayed into the combustion chamber by various spray patterns shown in FIG.

  In addition, when sprayed in the vicinity of the piston top dead center that transitions from the compression stroke to the expansion stroke, as shown in FIG. The air-fuel mixture present at the site can be effectively cooled.

  Further, as the water spray region, the direction of spray sprayed with water is focused on the vicinity of the cylinder bore, which is the outer peripheral side in the combustion chamber 20, so that knocking existing on the outer peripheral side is generated. The part (end gas part) which is easy to do can be cooled efficiently, and knocking can be suppressed with a small amount of water spray.

  The combustion control device for an internal combustion engine configured as described above can be operated as described below.

  Although it is desirable to set the compression ratio high in order to maximize the thermal efficiency of the engine, knocking tends to occur as the load increases. Therefore, as shown in FIG. 6, the target compression ratio map has a lower compression ratio as the load increases. It is set. When the rapid acceleration (b) is executed from the steady running state (a) on such a target compression ratio map, the target compression ratio changes rapidly from the high compression ratio to the low compression ratio. In the time chart shown in FIG. 12, a steady running state is shown until immediately before time t1, a high compression ratio is selected as the target compression ratio, and the difference dCR from the actual compression ratio is also equal to or less than the set value. Immediately before time t1, when the target compression ratio is set to a low compression ratio (see time t2) by suddenly depressing the accelerator pedal, the difference dCR from the actual compression ratio increases abruptly. At t1, the allowable set value is exceeded. At this time t1, it is determined by the water spray mechanism B that water spray is required in the combustion chamber 20, and water spray is performed immediately after the intake valve 27 of the combustion cycle is closed or near the piston top dead center position where the compression stroke shifts to the expansion stroke. Is executed.

  The compression ratio changing operation of the variable compression ratio mechanism A generates a response delay due to a reaction delay due to a load from the combustion gas pressure in the combustion chamber 20 or a response delay due to the inertial force / friction of the multi-link mechanism D, etc. The actual compression ratio output by the motor encoder of the motor 18 remains temporarily higher than the target compression ratio.

  By the water spray for each combustion cycle, the air-fuel mixture in the combustion chamber 20 and the end gas region in the vicinity of the wall surface of the combustion chamber 20 are cooled, so that the in-cylinder temperature is lowered and the occurrence of knocking is avoided. For this reason, it is possible to reduce knocking measures such as torque reduction due to air volume restriction and ignition timing retardation correction, etc., and to maximize the fuel efficiency improvement effect by the variable compression ratio mechanism A without accompanying poor acceleration and fuel efficiency deterioration. Can be obtained to the limit. Further, it is not impossible to set the compression ratio so that the intake air amount becomes the knock limit intake air amount in a steady condition before acceleration so that knocking does not occur even if a sudden acceleration request occurs.

  If the difference dCR of the actual compression ratio with respect to the target compression ratio is reduced to a predetermined value or less at the time t3 by the operation of the variable compression ratio mechanism A, it is determined that there is no need for water spray, At the time t4 when the spraying is stopped and the actual compression ratio matches the target compression ratio, the water spray control accompanying the current acceleration is finished.

  In the present embodiment, the following effects can be achieved.

  (A) Variable compression ratio mechanism A that changes the effective compression ratio, target compression ratio calculation means S2 that obtains a target effective compression ratio from operating conditions, and an actual effective compression ratio that is realized by the variable compression ratio mechanism A is detected. Means S4, a water spray mechanism B capable of spraying water into the combustion chamber 20 according to engine operating conditions, and a control means for operating the water spray mechanism B when the actual effective compression ratio is higher than the target effective compression ratio. 30. For this reason, in transient operation, if the actual compression ratio is higher than the target compression ratio, the temperature of the unburned mixture can be reduced by water spray, resulting in poor acceleration or suppressing knocking while suppressing fuel consumption deterioration. On the other hand, since the knock limit compression ratio can be set in a steady state, the fuel efficiency improvement effect by the variable compression ratio mechanism A can be obtained to the maximum.

  (A) The water spray amount from the water spray mechanism B is increased according to the difference dCR between the target effective compression ratio and the actual effective compression ratio, that is, the water spray amount is increased as knocking is likely to occur. The amount of water spray can be suppressed to an appropriate amount.

  (C) The variable compression ratio mechanism A is composed of a multi-link mechanism D capable of adjusting the piston top dead center position. In the internal combustion engine in which the effective compression ratio is variable by changing the piston top dead center position, The effects (a) and (b) can be obtained.

  (D) The water spraying by the water spraying mechanism B is performed after the intake valve 27 is closed, so that it does not affect the intake air intake amount. The vaporization time can be maximized. In addition, the entire combustion chamber 20 can be cooled.

  (E) Water spraying by the water spray mechanism B is performed in the vicinity of the top dead center of the piston that shifts from the compression stroke to the expansion stroke, so that the part can be cooled at a timing at which knocking is likely to occur. .

  (F) The water spray by the water spray mechanism B is efficiently sprayed toward the outer periphery of the combustion chamber 20 to efficiently cool a portion (end gas portion) where knocking is likely to occur, and a small amount of water spray. Can effectively suppress knocking.

  (G) Since the ignition advance control device 31 reduces the ignition timing retardation correction in accordance with the amount of water spray from the water spray mechanism B, the ignition timing retardation correction is reduced, and the thermal efficiency is less reduced. Fuel consumption does not deteriorate.

(Second Embodiment)
14 and 15 show a second embodiment of a combustion control device for an internal combustion engine to which the present invention is applied, FIG. 14 is a system configuration diagram of a variable compression ratio mechanism of the first embodiment, and FIG. 15 is a diagram of the second embodiment. It is a system block diagram of a variable compression ratio mechanism. In the present embodiment, a configuration in which the variable compression ratio mechanism A is configured by the variable valve mechanism C or both the variable valve mechanism C and the variable compression ratio mechanism A1 by the multi-link mechanism D is added to the first embodiment. It is a thing. The same devices as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

  In the first example of the combustion control apparatus for an internal combustion engine in the present embodiment, the variable compression ratio mechanism A is constituted by a variable valve mechanism C of an intake valve 27 as shown in FIG. The configuration of the water spray mechanism B and other configurations are not particularly illustrated, but are configured in the same manner as in the first embodiment. The variable valve mechanism C of the intake valve 27 has been previously proposed by the applicant of the present application. However, since it is publicly known, for example, in Japanese Patent Application Laid-Open No. 11-107725, only the outline thereof will be described.

  The variable valve mechanism C advances or retards the lift / operation angle variable mechanism 41 that changes the lift / operation angle of the intake valve 27 and the phase of the center angle of the lift (phase with respect to a crankshaft (not shown)). The phase variable mechanism 61 is combined.

  The variable lift / operating angle mechanism 41 includes a drive shaft 42 rotatably supported by a cam bracket (not shown) above the cylinder head 21, and an eccentric cam 43 fixed to the drive shaft 42 by press-fitting or the like. The control shaft 52 is rotatably supported by the same cam bracket at a position above the drive shaft 42, and is swingably supported by an eccentric cam portion 58 of the control shaft 52. The rocker arm 46 and a swing cam 49 that contacts the tappet 50 disposed at the upper end of each intake valve 27 are provided.

  The eccentric cam 43 and the rocker arm 46 are linked by a link arm 44, and the rocker arm 46 and the swing cam 49 are linked by a link member 48. The drive shaft 42 is driven by the crankshaft 7 of the engine via a timing chain or a timing belt. The eccentric cam 43 has a circular outer peripheral surface centered at a point offset from the shaft center of the drive shaft 42 by a predetermined amount, and an annular portion of the link arm 44 is rotatably fitted to the outer peripheral surface. Yes.

  The rocker arm 46 is supported at its substantially central portion by the eccentric cam portion 58 so as to be swingable. The arm portion of the link arm 44 is linked to one end portion thereof via a connecting pin 45 and the other end portion. In addition, the upper end portion of the link member 48 is linked via the connecting pin 47. The eccentric cam portion 58 is eccentric from the axis of the control shaft 52, and the rocking center of the rocker arm 46 changes according to the angular position of the control shaft 52.

  The swing cam 49 is rotatably supported by being fitted to the outer periphery of the drive shaft 42, and a lower end portion of the link member 48 is linked to an end portion extending laterally via a connecting pin 57. . On the lower surface of the swing cam 49, a base circle surface concentric with the drive shaft 42 and a cam surface extending in a predetermined curve from the base circle surface are continuously formed. The base circle surface and the cam surface are in contact with the upper surface of the tappet 50 according to the swing position of the swing cam 49. That is, the base circle surface is a base circle section where the lift amount is “0”. When the swing cam 49 swings and the cam surface contacts the tappet 50, the base circle section lifts gradually. Become. A slight lap section is provided between the base circle section and the lift section.

  The control shaft 52 is configured to rotate within a predetermined angle range by a lift / operation angle control actuator 53 provided at one end. The lift / operating angle control actuator 53 is composed of, for example, a hydraulic cylinder or the like, and is controlled by converting a control signal from the engine control unit 30 into a control hydraulic pressure by a hydraulic control unit 54. The rotation angle of the control shaft 52 is detected by a control shaft sensor (not shown).

  When the drive shaft 42 rotates, the variable lift / operating angle mechanism 41 configured as described above moves the link arm 44 up and down by the cam action of the eccentric cam 43, and the rocker arm 46 swings accordingly. The swing of the rocker arm 46 is transmitted to the swing cam 49 via the link member 48 to swing the swing cam 49. By the cam action of the swing cam 49, the tappet 50 is pressed and acts to lift the intake valve 27.

  When the angle of the control shaft 52 is changed via the lift / operating angle control actuator 53, the initial position of the rocker arm 46 changes and the initial swing position of the swing cam 49 changes. For example, if the eccentric cam portion 58 is positioned upward in the figure, the rocker arm 46 is positioned upward as a whole, and the end portion of the swing cam 49 on the side of the connecting pin 57 is relatively lifted upward. Become. That is, the initial position of the swing cam 49 is inclined in a direction in which the cam surface is separated from the tappet 50. Therefore, when the swing cam 49 swings with the rotation of the drive shaft 42, the base circle surface continues to be in contact with the tappet 50 and the period during which the cam surface contacts the tappet 50 is short. Therefore, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.

  Conversely, assuming that the eccentric cam portion 58 is positioned downward in the figure, the rocker arm 46 is positioned downward as a whole, and the end portion of the swing cam 49 on the side of the connecting pin 57 is pushed downward relatively. It becomes a state. That is, the initial position of the swing cam 49 is inclined in a direction in which the cam surface approaches the tappet 50. Therefore, when the swing cam 49 swings with the rotation of the drive shaft 42, the portion that comes into contact with the tappet 50 immediately shifts from the base circle surface to the cam surface. Therefore, the lift amount is increased as a whole, and the operating angle is increased.

  Since the initial position of the eccentric cam portion 58 can be continuously changed, the valve lift characteristic is continuously changed accordingly. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously. Depending on the layout of each part, for example, the opening timing and closing timing of the intake valve 27 change substantially symmetrically with the change in the lift and operating angle.

  The phase variable mechanism 61 includes a sprocket 62 provided at the front end of the drive shaft 42, and a phase control actuator 63 that relatively rotates the sprocket 62 and the drive shaft 42 within a predetermined angular range. , Is composed of. The sprocket 62 is linked to the crankshaft 7 via a timing chain or timing belt (not shown). The phase control actuator 63 is composed of, for example, a hydraulic rotary actuator, and is controlled by converting a control signal from the engine control unit 30 into a control hydraulic pressure by the hydraulic control unit 55. Due to the action of the phase control actuator 63, the sprocket 62 and the drive shaft 42 are relatively rotated, and the lift center angle in the valve lift is retarded. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The control state of the phase variable mechanism 61 is detected by a drive shaft sensor (not shown) that responds to the rotational position of the drive shaft 42.

  The variable valve mechanism C including the lift / operating angle variable mechanism 41 and the phase variable mechanism 61 described above can arbitrarily control the opening timing and closing timing of the intake valve 27. By controlling the valve closing timing, it is possible to adjust the intake air amount into the cylinder 2, that is, the cylinder air amount, and change the effective compression ratio of the engine without changing the piston stroke or the piston top dead center position. Can be made. That is, the effective compression ratio of the engine can be set to a high compression ratio by increasing the cylinder air amount by bringing the valve closing timing close to bottom dead center. In addition, if the valve closing timing is set to the advance side with respect to the bottom dead center, the valve is advanced more, and conversely if the valve closing timing is set to the retard side, the valve is further delayed. The amount of cylinder air can be reduced, and the effective compression ratio of the engine can be reduced to a low compression ratio.

  Then, the engine controller ECU 30 calculates the target compression ratio of the engine according to the operating state based on the target compression ratio map of FIG. Activate C.

  The responsiveness of changing the compression ratio of the variable compression ratio mechanism A by the variable valve mechanism C is higher than that of the multi-link variable compression ratio mechanism A in the first embodiment. However, when the target compression ratio is suddenly changed from a high compression ratio to a low compression ratio, such as when sudden acceleration is executed from a steady running state, the variable valve mechanism C is used with a slight time delay. A change in the intake air amount is realized. For this reason, a difference dCR is generated in a short time between the actual effective compression ratio of the variable compression ratio mechanism A and the target compression ratio command. Accordingly, when the difference dCR is calculated and the difference dCR exceeds a predetermined value set in advance, it is determined that the operation state is likely to cause knocking, and water spray is performed from the water spray valve 22 of the water spray mechanism B. By outputting the water spray command to be executed, knocking can be prevented without causing a decrease in output due to an insufficient air amount or a deterioration in fuel consumption due to retarded correction of ignition timing.

  In the second example of the combustion control apparatus for an internal combustion engine in the present embodiment, as shown in FIG. 15, the variable compression ratio mechanism A is replaced by a variable valve mechanism C of the intake valve 27 and a variable compression ratio mechanism by a multi-link mechanism D. And A1. The configuration of the water spray mechanism B and other configurations are not particularly illustrated, but are configured in the same manner as in the first embodiment.

  In the combustion control apparatus for an internal combustion engine of the second embodiment, a variable compression ratio mechanism A1 using a multi-link mechanism D having a relatively low response speed and a variable compression ratio mechanism A using a variable valve mechanism C having a relatively high response speed. Therefore, in response to a sudden decrease in the target compression ratio, first, the variable compression ratio mechanism A by the variable valve mechanism C is operated to realize the actual effective compression ratio, and the subsequent complex Realization of variable compression ratio mechanism A1 by link mechanism D Improving the responsiveness and stability of compression ratio control by controlling to increase the effective compression ratio by variable valve mechanism C in response to a decrease in compression ratio. Can do. Even in this case, when the target compression ratio is suddenly changed from the high compression ratio to the low compression ratio, such as when sudden acceleration is executed from the steady running state, the variable valve is operated with a slight time delay. The change of the intake air amount by the mechanism C is realized. For this reason, a difference dCR is generated in a short time between the actual effective compression ratio of the variable compression ratio mechanism A and the target compression ratio command. Therefore, the difference dCR is calculated, and when the difference dCR exceeds a predetermined value set in advance, it is determined that the operation state is likely to cause knocking, and water spray is performed from the water spray valve of the water spray mechanism B. By outputting a water spray command to perform knocking, it is possible to prevent knocking without causing a decrease in output due to an insufficient amount of air or a deterioration in fuel consumption due to retarded correction of ignition timing.

  In the present embodiment, in addition to the effects (a) to (ki) in the first embodiment, the following effects can be achieved.

  (H) The variable compression ratio mechanism A is composed of a variable valve mechanism C that can change the valve opening period and / or phase of the intake valve 27, and controls the intake air amount in accordance with the closing timing of the intake valve 27. By making the effective compression ratio variable, in the engine in which the effective compression ratio is made variable by the variable valve C, the effects (a) and (b) are obtained.

  (K) The variable compression ratio mechanism A is a variable compression ratio mechanism A1 that includes a variable valve mechanism C that can change the valve opening period and / or phase of the intake valve 27 and a multi-link mechanism D that can adjust the piston top dead center position. The effective compression ratio is made variable by both the valve closing timing of the intake valve 27 and the piston top dead center position, so that both the variable valve mechanism C and the multi-link mechanism D are effective compression ratios. In the engine in which is variable, the effects (a) and (b) are obtained.

The system block diagram of the combustion control apparatus of the internal combustion engine which shows one Embodiment of this invention. The front view (A) and partial enlarged view (B) of the variable compression ratio mechanism of a combustion control apparatus. The side view of a variable compression ratio mechanism. Sectional drawing of a combustion chamber which shows the example of arrangement | positioning of the water spray valve in the combustion control apparatus of an internal combustion engine. Explanatory drawing of water spray pattern (A)-(D). The figure which shows the map of target compression ratio. The characteristic view which showed the water spray amount characteristic with respect to the difference of a target compression ratio and an actual compression ratio. The characteristic view which showed the water spray correction factor with respect to engine load. The characteristic view which showed the water spray correction factor with respect to engine speed. The characteristic view which showed the water spray correction factor with respect to cooling water temperature. The flowchart which shows a water spray control routine. The time chart by execution of the flowchart which shows a water spray control routine. Sectional drawing of a combustion chamber which shows another example of arrangement | positioning of a water spray valve. The system block diagram of the variable compression ratio mechanism of the combustion control apparatus of the internal combustion engine which shows the 1st Example of 2nd Embodiment of this invention. The system block diagram of the variable compression ratio mechanism of the combustion control apparatus of the internal combustion engine which shows 2nd Example of 2nd Embodiment of this invention.

Explanation of symbols

A, A1 Variable compression ratio mechanism B Water spray mechanism C Variable valve mechanism D Double link mechanism 1 Cylinder block 2 Cylinder 3 Piston 4 Piston pin 5 Upper link 6 Lower link 7 Crank shaft 8 Crank pin 11 Control link 12 Control shaft 30 Control Engine controller ECU as a means

Claims (10)

A variable compression ratio mechanism for changing the effective compression ratio;
Target compression ratio calculation means for obtaining a target effective compression ratio from the operating conditions;
Means for detecting an actual effective compression ratio realized by the variable compression ratio mechanism;
A water spray mechanism capable of spraying water into the combustion chamber according to engine operating conditions;
E Bei and control means for actuating the water spraying mechanism is higher than the set value the difference is preset for the target effective compression ratio of the actual effective compression ratio,
The internal combustion engine, wherein the set value is corrected to be low when the load on the internal combustion engine is relatively high, the rotational speed of the internal combustion engine is relatively low, or the cooling water temperature of the internal combustion engine is relatively high. Combustion control device.   The combustion control apparatus for an internal combustion engine according to claim 1, wherein the water spray amount from the water spray mechanism is increased according to a difference between a target effective compression ratio and an actual effective compression ratio.   2. The variable compression ratio mechanism is configured by a variable valve mechanism that can change a closing timing of an intake valve, and an effective compression ratio is variable depending on the closing timing of the intake valve. Or the combustion control apparatus of the internal combustion engine of Claim 2.   The variable compression ratio mechanism is constituted by a multi-link mechanism capable of adjusting a piston top dead center position, and the effective compression ratio is variable by changing the piston top dead center position. A combustion control device for an internal combustion engine according to claim 1 or 2.   The variable compression ratio mechanism includes a variable valve mechanism that can change the closing timing of the intake valve and a multi-link mechanism that can adjust the piston top dead center position, and the valve closing timing of the intake valve and the piston top dead center position. The combustion control device for an internal combustion engine according to claim 1 or 2, wherein the effective compression ratio is variable.   The combustion control apparatus for an internal combustion engine according to any one of claims 1 to 5, wherein the water spraying by the water spraying mechanism is performed after the intake valve is closed.   The combustion control device for an internal combustion engine according to claim 6, wherein the water spray after the valve closing is performed immediately after the intake valve is closed.   6. The internal combustion engine according to claim 1, wherein water spraying by the water spray mechanism is performed in the vicinity of a top dead center of a piston that shifts from a compression stroke to an expansion stroke. Combustion control device.   The combustion control apparatus for an internal combustion engine according to any one of claims 1 to 8, wherein the water spray by the water spray mechanism is sprayed so that a vicinity of a bore in the combustion chamber is dense. It has an ignition timing control device that adjusts the ignition timing,
The combustion of the internal combustion engine according to any one of claims 1 to 6, wherein the ignition timing control device reduces ignition timing retardation correction in accordance with a water spray amount from a water spray mechanism. Control device.