JP4849475B2 - Ignition timing control device for spark ignition internal combustion engine - Google Patents

Description

  The present invention relates to an ignition timing control device that corrects an ignition timing to be retarded in order to raise the temperature of an exhaust purification catalyst in a spark ignition internal combustion engine.

Patent Document 1 discloses an ignition timing control device that controls the ignition timing using the most retarded ignition timing set according to the operating state of the internal combustion engine as a retard-side guard.
JP 2006-132420 A

  By the way, in order to quickly raise the temperature of the exhaust gas purification catalyst immediately after the start of the cold engine, the ignition timing may be retarded. However, the limitation by the retard side guard (retard limiter) is excessively slow. While it is set for the purpose of avoiding a decrease in output and a decrease in combustion stability due to an angle correction, the retardation correction for the catalyst temperature increase gives priority to the catalyst temperature increase over the output and combustion stability. Since it is a process, the retardation limiter for limiting the temperature of the catalyst is limited by the retardation limiter, so that a sufficient temperature increase effect may not be obtained.

  The present invention has been made in view of the above problems, and it is possible to avoid a decrease in temperature increase effect due to excessive limitation of ignition timing retardation correction for catalyst temperature increase. With the goal.

Therefore, according to the first aspect of the present invention, when the ignition timing is retarded in accordance with the retard correction amount set based on the engine temperature and the engine rotation speed in order to increase the temperature of the catalyst , the retard correction amount is used. Accordingly, the retard limiter is changed to the retard side, and the change of the retard limiter according to the retard correction amount is limited by the final limit limiter .
According to the above invention, when the ignition timing is corrected to retard the temperature of the catalyst , the retard correction amount is set based on the engine temperature and the engine rotation speed, so that the catalyst warm-up performance and the engine combustion stability are set. If the retard angle correction amount for increasing the catalyst temperature is changed, the retard angle limiter is changed in conjunction with this, so that the retard angle request for increasing the temperature is excessive by the retard angle limiter. So that you are not limited to Further, the change of the retard limiter is limited by the final limit limiter, and even if there is a request for raising the catalyst temperature, the delay angle correction exceeding the final limit limiter (for example, the misfire limit) is prohibited.

According to a second aspect of the invention, in the first aspect of the invention, the retard correction amount is set so that the ignition timing is retarded more as the engine temperature is higher and the engine speed is higher. did.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the spark ignition type internal combustion engine includes a variable valve mechanism that changes an opening characteristic of the intake valve, and delays the ignition timing for raising the catalyst temperature. Corresponding to the angle correction, the variable valve mechanism is controlled to correct the opening characteristic of the intake valve, and the difference between the target opening characteristic and the actual opening characteristic when the opening characteristic of the intake valve is corrected Based on the above, the retard correction amount of the ignition timing for raising the catalyst temperature is corrected.

According to the above invention, by changing the opening characteristic of the intake valve, the ignition timing can be retarded more, but the actual opening characteristic has not converged to the target opening characteristic for expanding the retarding limit. In the state, since the desired retardation correction cannot be performed, the ignition timing retardation correction amount for increasing the catalyst temperature is corrected according to the difference between the target opening characteristic and the actual opening characteristic.
According to a fourth aspect of the invention, in the third aspect of the invention, the variable valve mechanism is controlled so that the closing timing of the intake valve is close to the intake bottom dead center.

According to the above invention, when the ignition timing is corrected to retard the temperature of the catalyst, the intake valve closing timing is set near the intake bottom dead center by controlling the variable valve mechanism that changes the opening characteristics of the intake valve. And increase the actual compression ratio to increase the combustion speed and expand the ignition timing retard limit.
According to a fifth aspect of the present invention, in the fourth aspect of the invention, the retard correction amount is reduced as the closing timing of the intake valve is farther from the bottom dead center.
According to the above invention, as the intake valve closing timing is further away from the bottom dead center, the retard angle that can maintain the combustion stability becomes smaller. Therefore, as the intake valve closing timing is further away from the intake bottom dead center, the retardation correction amount is increased. Reduce.
According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, when the ignition timing retardation correction amount for increasing the catalyst temperature is decreased and the ignition timing is advanced. In addition, the advance angle change amount of the ignition timing for each ignition is limited so as not to exceed the change amount limiter.

  According to the present invention, the ignition timing for the catalyst temperature rise suddenly decreases the retard correction amount, and if the ignition timing is rapidly advanced, the engine output torque changes suddenly, so as to avoid a sudden change in the output torque, The amount of change in the advance angle of the ignition timing for each ignition is limited so as not to exceed the change amount limiter, and the advance speed of the ignition timing is suppressed.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of a spark ignition internal combustion engine for a vehicle according to an embodiment.
In FIG. 1, an electronic control throttle device 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of the internal combustion engine 101, and through the electronic control throttle device 104 and a downstream intake valve 105, Air is sucked into the combustion chamber 106.

A fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder.
The fuel injection valve 131 is supplied with fuel adjusted to a predetermined pressure, and injects an amount of fuel proportional to the injection pulse width (valve opening time) of the injection pulse signal sent from the engine control module (ECM) 114. .

The air-fuel mixture in the combustion chamber 106 is ignited and combusted by spark ignition by the spark plug 151.
The ignition plug 151 is directly attached with an ignition coil 152 with a built-in power transistor, and an ignition control signal for controlling on / off of the power transistor is output from the engine control module 114, so that each cylinder has an ignition control signal. The ignition timing is controlled.

In the present embodiment, the ignition timing control device includes the engine control module 114, the ignition plug 151, and the power coil built-in ignition coil 152.
The fuel injection valve 131 may be a direct injection type fuel injection device in which fuel is directly injected into the combustion chamber 106.

The combustion exhaust in the combustion chamber 106 is discharged through an exhaust valve 107, purified by a front catalytic converter 108 and a rear catalytic converter 109 (exhaust purification catalyst), and then released into the atmosphere.
Note that the exhaust purification catalyst is not limited to the configuration including the front catalytic converter 108 and the rear catalytic converter 109, but may be an engine including only one catalyst.

Further, the front catalytic converter 108 and the rear catalytic converter 109 are of a three-way catalyst type, but may be an oxidation catalyst or a catalyst having a trap function of exhaust particulates.
The exhaust valve 107 is driven to open and close by a cam 111 provided on the exhaust-side camshaft 110 while maintaining certain open characteristics (maximum valve lift, valve operating angle, and valve timing).

On the other hand, the opening characteristics of the intake valve 105 are variable by a variable lift mechanism 112 and a variable valve timing mechanism 113 as variable valve mechanisms.
The variable lift mechanism 112 is a mechanism that continuously varies the maximum valve lift amount of the intake valve 105 together with the valve operating angle. When the maximum valve lift amount is changed (increased), the valve operating angle is accordingly increased. Is a mechanism for increasing (decreasing) at the same time.

The variable valve timing mechanism 113 continuously changes the central phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake valve drive shaft 3 to be described later with respect to the crankshaft 120. Mechanism.
The engine control module 114 having a built-in microcomputer has a fuel injection valve 131, a power transistor built-in ignition coil 152, an electronically controlled throttle device 104, a variable lift mechanism 112, and a variable valve timing by arithmetic processing according to a program stored in advance. A control signal is output to the mechanism 113.

A unit for controlling the fuel injection amount and ignition timing of the internal combustion engine 101 and a unit for controlling the opening characteristics of the intake valve 105 by the variable lift mechanism 112 and the variable valve timing mechanism 113 can be provided separately.
Detection signals from various sensors are input to the engine control module 114.

  Examples of the various sensors include a hot wire type air flow sensor 115 that detects an intake air amount (mass flow rate) Q of the internal combustion engine 101, an accelerator sensor 116 that detects an opening degree of an accelerator pedal operated by a vehicle driver, and a crankshaft. By detecting a detected portion provided on a signal plate supported by 120, a crank angle sensor 117 that outputs a unit crank angle signal POS for each unit crank angle, and a throttle sensor 118 that detects an opening TVO of the throttle valve 103b. , A water temperature sensor 119 for detecting a cooling water temperature TW (engine temperature) of the internal combustion engine 101, and a detected portion provided on a signal plate supported by an intake valve drive shaft 3 to be described later, thereby detecting the intake valve drive shaft. Cam sensor 132 for outputting a cam signal at every three reference rotational positions, throttle valve An intake pressure sensor 136 that detects an intake pipe internal pressure (intake valve upstream pressure) 103b downstream, an air-fuel ratio sensor 137 that is disposed upstream of the front catalytic converter 108 and detects the air-fuel ratio from the oxygen concentration in the exhaust, etc. are provided. It has been.

Further, an on / off signal of the start switch 135 is input to the engine control module 114.
The unit crank angle signal POS is generated on the signal plate so that a tooth loss occurs at every crank angle (180 ° CA for four cylinders) corresponding to the stroke phase difference (ignition interval) between the cylinders of the internal combustion engine 101. A detection unit is set, and the reference crank angle position REF for each stroke phase difference is detected by detecting the tooth missing position of the unit crank angle signal POS based on the output cycle of the unit crank angle signal POS. Be able to.

Then, from the phase difference between the cam signal from the cam sensor 132 and the reference crank angle position REF, the advance / retard angle amount of the valve timing (center phase of the operating angle) by the variable valve timing mechanism 113 is detected.
Further, the rotational speed NE of the internal combustion engine 101 is calculated based on the detection interval time of the reference crank angle position REF.

FIG. 2 is a perspective view showing the structure of the variable lift mechanism 112. However, the variable lift mechanism 112 is not limited to the structure shown in FIG.
In the internal combustion engine 101 of the present embodiment, a pair of intake valves 105 is provided for each cylinder, and an intake valve drive shaft 3 that is rotationally driven by the crankshaft 120 is disposed above the intake valves 105 in the cylinder row direction. Is supported rotatably.

A swing cam 4 that contacts the valve lifter 105a of the intake valve 105 and opens and closes the intake valve 105 is fitted on the intake valve drive shaft 3 so as to be relatively rotatable.
Between the intake valve drive shaft 3 and the swing cam 4, a variable lift mechanism 112 for continuously changing the operating angle and the maximum valve lift amount of the intake valve 105 is provided.
In FIG. 2, the variable lift mechanism 112 is shown only on one side of the pair of intake valves 105, and the other side is not shown.

A variable valve timing mechanism that continuously changes the center phase of the operating angle of the intake valve 105 by changing the rotational phase of the intake valve drive shaft 3 with respect to the crankshaft 120 at one end of the intake valve drive shaft 3. 113 is arranged.
As shown in FIGS. 2 and 3, the variable lift mechanism 112 includes a circular drive cam 11 that is eccentrically fixed to the intake valve drive shaft 3 and a ring that is externally fitted to the drive cam 11 so as to be relatively rotatable. A link 12, a control shaft 13 that extends substantially parallel to the intake valve drive shaft 3 in the cylinder row direction, a circular control cam 14 that is eccentrically fixed to the control shaft 13, and a relative position to the control cam 14. A rocker arm 15 that is rotatably fitted and has one end connected to the tip of the ring-shaped link 12, and a rod-shaped link 16 connected to the other end of the rocker arm 15 and the swing cam 4. Yes.

The control shaft 13 is rotationally driven by a motor 17 via a gear train 18, and a preset minimum lift position / minimum is set by a stopper 13 a provided integrally with the control shaft 13 coming into contact with the fixed side. Further rotation to the lift / actuation angle decreasing side is restricted at an angle position corresponding to the operation angle position.
The control shaft 13 can be rotationally driven by a hydraulic actuator, and the actuator for rotating the control shaft 13 is not limited to an electric actuator such as the motor 17.

With the above configuration, when the intake valve drive shaft 3 rotates in conjunction with the crankshaft 120, the ring-shaped link 12 moves substantially in translation through the drive cam 11, and the rocker arm 15 swings around the axis of the control cam 14. The swing cam 4 swings through the rod-shaped link 16 and the intake valve 105 is driven to open and close.
Further, by driving and controlling the motor 17 to change the rotation angle of the control shaft 13, the axial center position of the control cam 14 serving as the rocking center of the rocker arm 15 changes and the posture of the rocking cam 4 changes. .

As a result, the operating angle of the intake valve 105 and the maximum valve lift amount continuously change while the central phase of the operating angle of the intake valve 105 remains substantially constant.
A detection signal from an angle sensor 133 that detects the angular position of the control shaft 13 is input to the engine control module 114, and the control shaft 13 is rotated to a target angular position corresponding to a target valve lift amount. Based on the detection result of the angle sensor 133, the energization operation amount of the motor 17 is feedback-controlled.

Next, the configuration of the variable valve timing mechanism 113 will be described with reference to FIG.
In this embodiment, a vane variable valve timing mechanism is employed as the variable valve timing mechanism 113. However, the variable valve timing mechanism 113 is not limited to the vane type, and various known mechanisms such as an electromagnetic retarder may be used. Can be adopted.
A variable valve timing mechanism 113 shown in FIG. 4 is fixed to the cam sprocket 51 (timing sprocket) rotated by a crankshaft 120 via a timing chain and the end of the intake valve drive shaft 3 and is inserted into the cam sprocket 51. A rotating member 53 rotatably accommodated, a hydraulic circuit 54 for rotating the rotating member 53 relative to the cam sprocket 51, and a relative rotational position of the cam sprocket 51 and the rotating member 53 are selectively selected at predetermined positions. And a locking mechanism 60 that locks the frame.

The cam sprocket 51 includes a rotating part (not shown) having a tooth part meshed with a timing chain (or timing belt) on the outer periphery, and a housing that is disposed in front of the rotating part and rotatably accommodates the rotating member 53. 56, and a front cover and a rear cover (not shown) for closing the front and rear openings of the housing 56.
The housing 56 has a cylindrical shape with openings at the front and rear ends, and has a trapezoidal shape in cross section on the inner peripheral surface, and four partition walls 63 provided along the axial direction of the housing 56 are spaced by 90 °. It is projecting at.

The rotating member 53 is fixed to the front end portion of the intake valve driving shaft 3, and four vanes 78 a, 78 b, 78 c, 78 d are provided on the outer peripheral surface of the annular base 77 at 90 ° intervals.
Each of the first to fourth vanes 78a to 78d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 63. The recesses are separated from each other in the rotational direction, and the vanes 78a to 78d. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition wall 63.

The lock mechanism 60 is configured such that the lock pin 84 is engaged with an engagement hole (not shown) at the rotation position of the rotation member 53 on the maximum retard angle side.
The hydraulic circuit 54 includes two systems, a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 83. These hydraulic passages 91 and 92 are connected to a supply passage 93 and drain passages 94a and 94b through passage switching electromagnetic switching valves 95, respectively.

The supply passage 93 is provided with an engine-driven oil pump 97 that pumps oil in the oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.
The first hydraulic passage 91 is connected to four branch passages 91 d that are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance-side hydraulic chambers 82. It is connected to four oil holes 92 d that open to the retard side hydraulic chamber 83.

The electromagnetic switching valve 95 is configured such that an internal spool valve body relatively switches and controls the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
The engine control module 114 controls on / off of energization to the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal.

For example, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retard-side hydraulic chamber 83 through the second hydraulic passage 92. At the same time, the hydraulic oil in the advance side hydraulic chamber 82 is discharged from the first drain passage 94 a into the oil pan 96 through the first hydraulic passage 91.
Therefore, the internal pressure of the retard side hydraulic chamber 83 is high and the internal pressure of the advance side hydraulic chamber 82 is low, and the rotating member 53 rotates to the maximum retard side via the vanes 78a to 78b. The opening period (opening timing and closing timing) of the intake valve 105 is delayed, and the valve overlap is reduced.

On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance side hydraulic chamber 82 through the first hydraulic passage 91 and the retard side hydraulic pressure is supplied. The hydraulic oil in the chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the retard side hydraulic chamber 83 becomes low pressure.
For this reason, the rotation member 53 is rotated to the maximum advance side via the vanes 78a to 78d, whereby the opening period (opening timing and closing timing) of the intake valve 105 is accelerated, and the valve overlap is expanded. .

Here, the catalyst temperature increase control by the engine control module 114 will be described.
The engine control module 114 lowers exhaust emission by increasing the temperatures of the front catalytic converter 108 and the rear catalytic converter 109 (exhaust purification catalyst) early and reducing the time to reach the activation temperature immediately after the cold start. In order to achieve this, catalyst temperature increase control is performed to retard the ignition timing.

The block diagram of FIG. 5 is a block diagram showing a main process of ignition timing retardation correction control for raising the catalyst temperature.
In this embodiment, the ignition timing retardation correction control for raising the catalyst temperature may be expressed as FIR.
First, the control permission condition determination unit A001 determines whether the permission condition for the retardation correction control is satisfied.

The determination result in the control permission condition determination unit A001 is output to the valve timing operation unit A002 and the ignition retard amount calculation unit A003.
In the valve timing operation unit A002 (opening characteristic correcting means), when the permission condition is satisfied, the closing timing IVC of the intake valve 105 is controlled near the intake bottom dead center, and the actual closing timing at that time is controlled. IVC is output to the ignition retard amount calculation unit A003.

  When the valve timing operation unit A002 changes the closing timing IVC of the intake valve 105 to the vicinity of the intake bottom dead center, the control is performed as compared with the normal time in which the ignition timing retardation correction for raising the catalyst temperature is not performed. By reducing the speed (gain) and gradually changing the closing timing IVC, it is possible to avoid a decrease in operating stability of the internal combustion engine due to a sudden change in valve timing.

In the ignition retard amount calculation unit A003, when the permission condition is determined to be satisfied in the control permission condition determination unit A001, the actual closing timing IVC, the engine speed NE, the coolant temperature TW, and the like are set. Based on this, the ignition timing retard correction amount FIRTD for raising the temperature of the catalyst is calculated.
The retardation correction amount FIRTD calculated by the ignition retardation amount calculation unit A003 is output to a retardation correction unit (subtraction unit) A004, where the retardation correction is performed from a basic ignition timing (basic ignition advance value). By subtracting the amount FIRTD, the ignition timing is retarded (retard angle correcting means).

  In this embodiment, the ignition timing is indicated by an advance angle from the compression top dead center, and when the ignition timing is indicated by a positive angle, the ignition timing is performed before the compression top dead center, When the timing is indicated by a negative angle, it indicates that the ignition timing is performed after the compression top dead center, and by subtracting the retardation correction amount FIRTD from the basic ignition timing, only the retardation correction amount FIRTD is obtained. The ignition timing will be delayed.

Then, by delaying the ignition timing, the exhaust temperature rises, and the front catalytic converter 108 and the rear catalytic converter 109 (exhaust purification catalyst) are heated.
The basic ignition timing is set according to operating conditions such as engine load, engine rotation speed, cooling water temperature, idle / non-idle, and the basic ignition timing includes a knock correction amount that is retarded when knocking occurs. The ignition timing can be set.

Here, the determination of the permission condition of the retard correction control in the control permission condition determination unit A001 will be described in detail.
In the present embodiment, the retard correction control is permitted when all of the following conditions are satisfied.
(1) Start-up water temperature ≧ predetermined temperature (2) During idle operation (3) Start switch is turned on, and start switch is off Start-up water temperature ≧ predetermined temperature (4) Start switch is switched from on to off (5) Engine rotational speed is within a predetermined range (6) Variable valve mechanism is normal (7) Total heat generated by engine <predetermined value Each of the conditions (1) to (7) is as follows: For this reason, it is included in the permission conditions for the retard correction control.

Combustion stability is poor at low water temperatures (cold and warm), and misfiring occurs when the ignition timing is retarded. Therefore, combustion occurs at low water temperatures (cold and warm) according to the above condition (1). When the degree of stability is poor, the retardation correction for raising the temperature of the catalyst is prohibited, and the predetermined value is set based on the lowest temperature in the temperature range that can ensure the combustion stability even if the retardation is corrected. The
In addition, if the ignition timing is retarded during driving, the engine output is reduced and the drivability is degraded. Therefore, the ignition timing is retarded when idling (when the vehicle is stopped and the throttle is fully closed) according to condition (2). The retarding of the ignition timing is prohibited during non-idling (when the vehicle is running and the throttle is open), and the deterioration of the driving performance is avoided by correcting the retard for increasing the temperature of the catalyst.

Further, when starting (during cranking), the combustion stability is poor, and misfire occurs when the ignition timing is retarded. Therefore, when the combustion stability is bad at the start (during cranking) according to the above condition (3). , Delay angle correction for catalyst temperature rise is prohibited.
Further, the combustion stability is poor immediately after starting (immediately after the end of cranking), and misfire occurs when the ignition timing is retarded. Therefore, the combustion stability is poor immediately after starting (immediately after the end of cranking) according to the above condition (4). In some cases, the delay angle correction for raising the temperature of the catalyst is prohibited, and the predetermined time is the time until the combustion stability can withstand the delay angle correction of the ignition timing. Is preset.

  Further, when the engine rotational speed NE is low, the engine stall resistance is lowered, and when the engine rotational speed NE is high, the engine is not in the idling state. Therefore, according to the above condition (5), the ignition timing is corrected even when idling. Delay angle correction for catalyst temperature rise is prohibited in the low rotation range where there is a possibility of stalling, and delay angle correction for catalyst temperature rise is prohibited even in a high region where engine speed NE exceeds idle rotation To do.

  In addition, when the variable lift mechanism 112 and the variable valve timing mechanism 113 as the variable valve mechanism that makes the opening characteristic of the intake valve 105 variable do not operate normally, the opening characteristic of the intake valve 105 is changed during the retard correction control. If the ignition timing cannot be controlled to the target and the ignition timing is retarded as it is, the combustion stability of the engine is lowered. Therefore, when the variable lift mechanism 112 and the variable valve timing mechanism 113 are normal according to the condition (6), the catalyst ascends. Allow retard correction for temperature.

  Further, after the temperature increase of the front catalytic converter 108 and the rear catalytic converter 109 (exhaust gas purification catalyst) is completed, there is no need to continue the retarding of the ignition timing and the ignition timing retarding correction is further continued. Then, the fuel consumption deteriorates, so that the amount of heat given to the catalyst is estimated from the amount of heat generated by the engine according to the condition (7), and the total amount of heat generated by the engine (the amount of heat given to the catalyst) is sufficient to raise the temperature of the catalyst. When this is the case, the retardation correction for increasing the temperature of the catalyst is stopped.

Therefore, the predetermined value in the condition (7) is set from actual machine verification and simulation as the amount of heat necessary to raise the catalyst to near the activation temperature, and the total amount of heat generated by the engine is, for example, the fuel injection amount It is obtained from the integrated value.
The permission conditions for retard angle correction control are not limited to the above (1) to (7), and retard angle correction control is performed when a part of the above (1) to (7) is established. In addition, it is possible to add and replace conditions other than the above (1) to (7).

In the valve timing operation unit A002, when the permission condition as described above is satisfied, the ignition timing can be more retarded by controlling the closing timing IVC of the intake valve 105 to the vicinity of the intake bottom dead center. Thus, the catalyst temperature rising effect is enhanced.
That is, if the closing timing IVC of the intake valve 105 is controlled near the intake bottom dead center, the actual compression ratio increases, the combustion speed increases, and combustion stability can be ensured even if the ignition timing is retarded. The ignition timing can be retarded more than when IVC deviates from the intake bottom dead center.

Accordingly, the ignition timing retard amount calculation unit A003 sets the ignition timing retard correction amount on the assumption that the closing timing IVC of the intake valve 105 is controlled near the intake bottom dead center by the valve timing operation unit A002. calculate.
The block diagram of FIG. 6 shows details of the ignition retard amount calculation unit A003.
First, the basic retardation amount calculation unit B101 calculates a basic retardation correction amount FRBASEF from the engine rotational speed NE and the coolant temperature TW (engine temperature) at that time.

The basic retardation correction amount FRBASEF is set based on the warm-up performance of the catalyst and the combustion stability of the engine. Specifically, the higher the coolant temperature TW and the higher the engine speed NE, In order to retard the ignition timing more, it is set to a larger value.
The basic retard angle correction amount FRBASEF can be set by searching from a map with the engine speed NE and the coolant temperature TW as axes, and an arithmetic expression using the engine speed NE and the coolant temperature TW as variables. Further, the retard correction amount set based on one of the engine rotational speed NE and the cooling water temperature TW is corrected with the correction coefficient set based on the other, and the correction result is obtained. The basic retardation correction amount FRBASEF can be used.

On the other hand, the subtraction processing unit B102 calculates the deviation between the closing timing IVC of the intake valve 105 at that time and the target closing timing IVC (near the intake bottom dead center) when correcting the retard of the ignition timing.
The actual value of the closing timing IVC of the intake valve 105 can be obtained from the valve lift amount at that time detected by the sensor and the center phase of the operating angle (center position of the opening period).
The absolute value calculation unit B103 calculates the absolute value ERRVLT of the deviation calculated by the subtraction processing unit B102.

The correction coefficient calculation unit B104 calculates a correction coefficient HOSVL for correcting the basic retardation correction amount FRBASEF based on the absolute value ERRVLT.
The correction coefficient HOSVL is set to 1 when the absolute value ERRVLT is 0, and is set to a value smaller than 1 as the absolute value ERRVLT increases. When the absolute value ERRVLT is equal to or greater than a threshold value, HOSVL = 0. Retained.

The correction coefficient HOSVL is multiplied by the basic retardation correction amount FRBASEF in a multiplication unit B105 (retard angle correction amount correction means), and the result is output as a retardation correction amount FIRTD00.
That is, if the closing timing IVC of the intake valve 105 at that time coincides with the target closing timing IVC (near the intake bottom dead center) at the time of correcting the ignition timing retardation, the basic retardation correction amount FRBASEF = delay. Although the angle correction amount FIRTD00, the absolute value ERRVLT of the deviation between the closing timing IVC of the intake valve 105 at that time and the target closing timing IVC (near the intake bottom dead center) at the time of retarding the ignition timing increases. The basic retardation correction amount FRBASEF is reduced, and the retardation correction amount FIRTD00 is set.

As described above, when the closing timing IVC of the intake valve 105 is in the vicinity of the intake bottom dead center, the retard angle margin of the ignition timing can be maximized, and the retard angle margin that can maintain the combustion stability as the distance from the bottom dead center increases. Therefore, as the closing timing IVC of the intake valve 105 is further away from the intake bottom dead center, the basic retardation correction amount FRBASEF is reduced and corrected.
Therefore, for example, during the transient response in which the actual closing timing IVC is approaching the target closing timing IVC (near intake bottom dead center) when the ignition timing is corrected, the ignition timing is excessively corrected. In addition to preventing the ignition timing, if the actual closing timing IVC coincides with the target closing timing IVC (near intake bottom dead center) at the time of correcting the ignition timing retardation, the ignition timing can be retarded to the maximum.

  In the present embodiment, when the delay angle correction for increasing the catalyst temperature is performed, the closing timing IVC of the intake valve 105 is controlled near the intake bottom dead center, but in addition, the lift amount of the intake valve 105 is reduced. Or by retarding the opening timing IVO, it is possible to increase the intake flow velocity, thereby increasing the retarding allowance. In this case as well, the actual lift amount / opening timing IVO A similar effect can be obtained by setting the correction coefficient HOSVL based on the deviation from the target value.

Further, a plurality of the closing timing IVC, the opening timing IVO, and the lift amount of the intake valve 105 can be controlled toward the target for increasing the retarding allowance.
The retardation correction amount FIRTD00 output from the multiplication unit B105 is input to one of the two input terminals of the switching unit B106, and a fixed value of 0.0 is input to the other input terminal of the switching unit B106. Is done.

When the control permission condition determination unit A001 determines that the retard correction control is permitted, the switching unit B106 outputs the retard correction amount FIRTD00, and the control permission condition determination unit A001 outputs the retardation correction control. If it is determined not to permit the above, 0.0 is output.
That is, if the retard correction control is permitted, the retard correction amount FIRTD00 is output as it is to retard the ignition timing. If the retard correction control is not permitted, the retard of the ignition timing is output. In order to prohibit the correction, 0.0 is output as the retardation correction amount FIRTD00.

The output from the switching unit B106 is input to the change amount limiter unit B107.
The change amount limiter B107 (advance angle change limiting means) limits the change amount of the retard correction amount FIRTD for each ignition to a reference value or less, and avoids a sudden change in the engine output due to a sudden change in the retard correction amount FIRTD. To do.
In particular, when the engine (catalyst) warms up and the water temperature rises, the retard correction amount FIRTD decreases rapidly, and as a result, the ignition timing suddenly changes in the advance direction, causing the engine output to increase rapidly. Therefore, by limiting the rate of decrease of the retard correction amount FIRTD by the change amount limiter B107, and suppressing the rate of change of the ignition timing in the advance direction, the engine output increases rapidly. To prevent.

  The specific processing in the change amount limiter unit B107 is that the absolute value of the deviation between the retard correction amount FIRTD during the current ignition control and the retard correction amount FIRTD during the previous ignition control exceeds the reference value. In this case, if the retardation correction amount FIRTD is decreasing, the result of subtracting the reference value from the retardation correction amount FIRTD at the previous ignition control is set as the current retardation correction amount FIRTD, and the retardation correction amount FIRTD. If the time is an increase change, the result of adding the reference value to the retard correction amount FIRTD at the previous ignition control is set as the present retard correction amount FIRTD.

The retard correction amount FIRTD after the change speed is limited by the change amount limiter B107 is output to the retard correction unit A004, where the retard correction is performed from the basic ignition timing (basic ignition advance value). By subtracting the amount FIRTD, the ignition timing is retarded.
Further, the ignition timing after the subtraction correction by the retardation correction amount FIRTD is limited so as not to exceed the retardation limiter, and the ignition timing after the restriction processing is performed by the retardation limiter as necessary. Based on the above, actual ignition control is performed.

The block diagram of FIG. 7 shows the retard limit processing of the ignition timing by the retard limiter.
In FIG. 7, an ignition timing (ignition advance value) output from the retard angle correction unit A004 and a retard angle limiter ADVRMXFI are input to the retard angle limiter processing unit C201 (retard angle limiting unit), and the retard angle limiter ADVRMXFI is input. If the ignition timing (ignition advance value) output from the angle correction unit A004 is smaller than the retard limiter ADVRMXFI, the retard limiter ADVRMXFI is output as the final ignition timing (ignition advance value). The ignition timing is prevented from being delayed from the retard limiter ADVRMXFI.

The retard angle limiter ADVRMXFI is indicated by an advance angle from the compression top dead center, similarly to the ignition timing, and is set by the retard angle limit value setting unit C202 (retard angle limiter changing means).
In the retard angle limiter setting unit C202, the retard angle limiter ADVRMXFI is calculated according to the following equation.
ADVRMXFI = max (ADVRMX #, min (ADVRMX0 # −FIRTD, ADVRMXFI (n−1) + ADVLMT #))
In the above equation, ADVRMX # is the minimum limit value (final limit limiter) of the retard limiter, and any delay beyond this is an unacceptable value, and ADVRMX0 # is the basic retard limiter. The minimum limit value ADVRMX # and the basic retard limiter ADVRMX0 # may be fixed values, or may be variably set based on operating conditions such as engine load, engine speed, and coolant temperature.

FIRTD is the retardation correction amount. When the retardation correction control permission condition for increasing the catalyst temperature is satisfied, the required retardation amount for increasing the catalyst temperature is set, and the catalyst temperature increase is set. If the retard condition correction control permission condition for is not satisfied, 0 is set.
Further, ADVRMXFI (n−1) is the previous value of the retard angle limiter ADVRMXFI (the value at the previous ignition control), and ADVLMT # is the advance angle change limiter.

  Here, by subtracting the retardation correction amount FIRTD from the basic retardation limiter ADVRMX0 #, when the retardation correction control permission condition for raising the catalyst temperature is satisfied, only the retardation correction amount FIRTD is satisfied. It is avoided that the retardation limit is expanded and the retardation correction for increasing the catalyst temperature is limited by the basic retardation limiter ADVRMX0 #, so that a sufficient temperature increase effect cannot be obtained.

  The basic retard limiter ADVRMX0 # is set for the purpose of avoiding output reduction and combustion stability degradation due to excessive retardation correction, whereas retardation compensation for catalyst temperature rise is output. Therefore, at the time of retardation correction for increasing the catalyst temperature, the ignition timing corrected by the retardation correction amount FIRTD is higher than the basic retardation limiter ADVRMX0 #. If the basic retardation limiter ADVRMX0 # is set to the retardation limit, the retardation correction for raising the catalyst temperature cannot be sufficiently realized.

Therefore, by correcting the basic retard limiter ADVRMX0 # to the retard side by the retard correction amount FIRTD of the ignition timing, the retarded ignition timing does not exceed the retard limiter ADVRMXFI and become the retard side. (See FIG. 8).
Therefore, by changing the basic retard limiter ADVRMX0 # according to the retard correction amount FIRTD, the retard correction for the catalyst temperature rise is performed as required, and the catalyst temperature rise effect by the retard correction is obtained. On the other hand, when the retardation correction for raising the catalyst temperature is not performed, the basic retardation limiter ADVRMX0 # is set as the retardation limit, so that a decrease in output due to an excessive retardation can be avoided.

  In the above equation, the smaller one of the basic retard limiter ADVRMX0 # corrected with the retard correction amount FIRTD and ADVRMXFI (n-1) + ADVLMT # is selected, which is the retard correction amount FIRTD. If the decrease speed is high, the change in the advance direction of the retard limiter ADVRMXFI is fast, and as a result, the advance change of the ignition timing after being limited by the retard limiter ADVRMXFI becomes fast, resulting in a sudden change in the engine output. The change in the advance angle direction of the retard limiter ADVRMXFI due to the decrease in the retard angle correction amount FIRTD is limited within ADVLMT # for each ignition (advance angle change limiting means).

As a result, even if the rate of decrease of the retard correction amount FIRTD increases, it is possible to avoid sudden changes in the ignition timing and sudden changes in the engine output.
Further, in the above equation, the larger one of the minimum limit value ADVRMX # and min (ADVRMX0 # −FIRTD, ADVRMXFI (n−1) + ADVLMT #) is selected.
That is, the minimum limit value ADVRMX # is the minimum limit of the advance value of the ignition timing, and exceeds the minimum limit value ADVRMX # (final limit limiter) even at the time of delay correction for catalyst temperature rise. (Retard angle limiter change limiting means).

Therefore, even if the retardation correction for increasing the temperature of the catalyst is increased, it is possible to prevent the retardation from exceeding the minimum limit value ADVRMX #, and the occurrence of deterioration in combustion stability (misfire) due to excessive retardation. Can be avoided.
In the above embodiment, the basic retard limiter ADVRMX0 # is corrected with the retard correction amount FIRTD. However, when performing the retard correction for raising the catalyst temperature, the dedicated basic retard limiter ADVRMX0 # is used when raising the catalyst temperature. The retard angle limiter ADVRMXFI can be calculated according to the following formula.

ADVRMXFI = max (ADVRMX #, min (ADVRMX0 #, ADVRMXFI (n-1) + ADVLMT #))
The basic retard angle limiter ADVRMX0 # dedicated to the catalyst temperature rise may be a fixed value, and can be variably set based on operating conditions such as the engine speed NE and the coolant temperature TW. It is also possible to set the retard limiter ADVRMXFI = minimum limit value ADVRMX #.

  Further, the restriction due to ADVRMX # or ADVRMXFI (n-1) + ADVLMT # can be omitted.

The system figure of the internal combustion engine for vehicles in an embodiment. The perspective view which shows the detail of the variable lift mechanism in embodiment. Sectional drawing which shows the operating angle change mechanism of the said variable lift mechanism. Sectional drawing which shows the detail of the variable valve timing mechanism in embodiment. The block diagram which shows the main process of the retard angle correction control of the ignition timing for catalyst temperature rising in embodiment. The block diagram which shows the calculation process of the ignition retard amount in embodiment. The block diagram which shows the retard limiter process of the ignition timing in embodiment. 6 is a time chart showing the correlation between the retard limiter and the retard correction amount in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 108 ... Front catalytic converter (exhaust purification catalyst), 109 ... Rear catalytic converter (exhaust purification catalyst), 112 ... Variable lift mechanism (variable valve mechanism), 113 ... Variable valve Timing mechanism (variable valve mechanism), 114 ... Engine control module, 151 ... Spark plug, 152 ... Ignition coil with built-in power transistor

Claims (6)

In a spark ignition internal combustion engine equipped with an exhaust purification catalyst in the exhaust system,
A retard correction means for retarding the ignition timing in accordance with a retard correction amount set based on the engine temperature and the engine speed for increasing the temperature of the catalyst;
Retard angle limiting means for limiting the ignition timing so as not to exceed the retard angle limiter;
When the ignition timing is retarded by the retard correction means, the retard limiter is changed so that the retard limiter is changed to the retard side according to the retard correction amount of the ignition timing by the retard correction means. Means,
A retard limiter change restricting means for restricting a change of the retard limiter according to the retard correction amount by the retard limiter changing means with a final limit limiter;
An ignition timing control device for a spark ignition type internal combustion engine, comprising: 2. The spark according to claim 1, wherein the retard correction means sets the retard correction amount so that the ignition timing is retarded more as the engine temperature is higher and the engine speed is higher. Ignition timing control device for an ignition type internal combustion engine. The spark ignition internal combustion engine includes a variable valve mechanism that changes an opening characteristic of an intake valve;
An opening characteristic correction means for controlling the variable valve mechanism to correct the opening characteristic of the intake valve in correspondence with the retardation correction of the ignition timing by the retardation correction means;
A retard correction amount correcting means for correcting a retard correction amount of the ignition timing by the retard correction means based on a difference between a target opening characteristic and an actual opening characteristic in the opening characteristic correcting means;
An ignition timing control device for a spark ignition type internal combustion engine according to claim 1 or 2, wherein 4. The ignition timing control device for a spark ignition type internal combustion engine according to claim 3, wherein the open characteristic correction means controls the variable valve mechanism so that the closing timing of the intake valve is close to the intake bottom dead center. . 5. The spark ignition type internal combustion engine according to claim 4, wherein the delay angle correction amount correction means reduces the delay angle correction amount as the closing timing of the intake valve is farther from the bottom dead center. Ignition timing control device.   When the retard correction amount of the ignition timing by the retard correction means is decreased and the ignition timing changes, the advance angle that limits the advance angle change amount of the ignition timing for each ignition so as not to exceed the change amount limiter. The ignition timing control device for a spark ignition type internal combustion engine according to any one of claims 1 to 5, further comprising a change limiting means.

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