JP2011047378A - Method of controlling internal combustion engine system, and internal combustion engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling an internal combustion engine system and the internal combustion engine system, reducing mechanical loss and pump loss of a valve operating system while preventing the occurrence of abnormal combustion of mixed air in a cylinder. <P>SOLUTION: The method of controlling the internal combustion engine includes as operation modes of the engine: a late closing mode in which intake valve closing timing is set within a late closing range on a more retard side than the maximum filling and valve closing timing when an engine operation state is in a first operation zone on a high-load and low-speed side; and a late closing mode in which the intake valve closing timing is set within an early closing range on a more advance side than the intake valve closing timing and separated from the late closing range when the engine operation state is in a second operation zone on a lower-load or higher-speed side than the first operation zone, and even if a shift from the late closing mode to the early closing mode is demanded, prohibits the mode shift when a possibility that a re-shift from the early closing mode to the late closing mode is demanded exceeds a certain level (when YES at steps S53-S55). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention belongs to a technical field relates to a control method and an internal combustion engine system of an internal combustion engine system.

  2. Description of the Related Art Conventionally, there has been known an engine valve system that is provided with a variable lift mechanism that continuously changes the lift amount and opening / closing timing of an intake valve. For example, in the technique disclosed in Patent Document 1, the smaller the target air filling amount in the cylinder of the engine, the more the intake valve closing timing is advanced to reduce the air filling amount in the cylinder. In this way, in the low load operation region, the air filling amount is reduced without reducing the throttle valve to reduce the pump loss.

  Further, in the technique disclosed in Patent Document 2, in order to prevent abnormal combustion in the cylinder in the high load operation region where the compression ratio in the cylinder becomes high, the valve closing timing of the intake valve is set to the air filling amount in the cylinder. Is set apart from the maximum filling valve closing timing at which is maximized.

JP 2006-97647 A JP 2001-159348 A

By the way, in the engine provided with the variable lift mechanism shown in Patent Document 1 described above, from the viewpoint of reducing the mechanical loss of the engine, the closing timing of the intake valve is set to a range on the advance side of the maximum filling valve closing timing (earlier speed). It is preferable to control (set) within the (closed range). As a result, the lift amount of the intake valve is reduced and the mechanical loss is reduced as compared with the case where the intake valve closing timing is controlled within the retarded angle range (delayed closing range) from the maximum filling valve closing timing. be able to.

However, if the intake valve closing timing is controlled within the early closing range, the following problems occur. That is, when the engine is in the high load operation region, the transition from the low rotation region to the high rotation region is performed more rapidly than in the low and medium load operation region . Along with this, the air inertia force increases rapidly, so that the maximum filling valve closing timing is rapidly retarded. In order to secure a sufficient amount of air filling the cylinder, it is necessary to retard the intake valve closing timing at a speed corresponding to the retarding speed of the maximum filling valve closing timing. Therefore, the intake valve closing timing is further away from the target timing than the target timing. As a result, there is a problem that the required engine acceleration cannot be obtained due to insufficient cylinder air charge.

  Therefore, when the engine shifts to the high load and low rotation range, the intake valve closing timing is delayed with a certain margin with respect to the maximum filling valve closing timing in anticipation of the subsequent increase in engine speed (rpm). It is conceivable to set the angle side. As a result, a sufficient cylinder air charge can be secured against a rapid increase in engine speed in the high load operation region, and abnormal combustion can be generated by appropriately reducing the compression ratio in the high load operation region. Can be prevented.

  Therefore, in the low load to medium load operation region, the intake valve closing timing is set within the early closing range, while in the high load operation region, the intake valve closing timing is set within the late closing range separated from the early closing range. It is preferable. However, in this case, it is necessary to shift the intake valve closing timing between the late closing range and the early closing range according to the required load of the engine. Abnormal combustion may occur in accordance with the valve closing timing. Therefore, during the transition of the intake valve closing timing, it is preferable to temporarily drive the throttle valve in the closing direction in order to suppress the occurrence of abnormal combustion (in order to reduce the cylinder air charge amount).

  However, since there is a response speed error in the actuator that drives the throttle valve, it is possible to accurately estimate the current opening of the throttle valve in a situation where the transition between the early closing range and the late closing range is frequently performed. There is a problem that you can not. For this reason, the intake pressure and flow velocity on the downstream side of the throttle valve cannot be accurately predicted, and as a result, the prediction accuracy of the amount of air charged in the cylinder is significantly reduced. On the other hand, it is conceivable to control the throttle valve in advance (closed) regardless of the engine load, and then set each control parameter of the engine. Will increase the fuel efficiency of the engine.

The present invention has been made in view of the foregoing, it is an object of the control method and an internal combustion engine system of an internal combustion engine system, the early closing range of late closing range of the closing timing of the intake valve To improve the fuel efficiency of the internal combustion engine by reducing the mechanical loss and the pump loss of the valve system while preventing the abnormal combustion of the mixed air in the cylinder by elaborating on the transition of is there.

  In order to achieve the above object, according to the present invention, when the engine operating state of the internal combustion engine is in the first operating region on the high load low speed side, the intake valve closing timing is set within the slow closing range, while the engine operating state is Is in the second operating region at a lower load or higher speed than the first operating region, the intake valve closing timing is set within the early closing range, and the closing timing of the intake valve is set earlier than the late closing range. When shifting to the closing range, the throttle valve is temporarily driven in the closing direction, and then a request for shifting from the engine operating state in the first operating region to the engine state in the second operating region is made. If there is, then it is determined that there is a request for re-transition from the second operation region to the first operation region within a predetermined period, and when this possibility is above a predetermined level, the intake valve is closed. The valve timing was kept in the late closing range.

Specifically, in the invention of claim 1, the intake communication passage - cylinder defining a combustion chamber with the piston you reciprocation, air is introduced into the combustion chamber passes, and are driven by the crankshaft, the An internal combustion engine having an intake valve capable of shutting off the intake passage from the combustion chamber , a throttle valve provided in the intake passage so as to be opened and closed, and a closing timing of the intake valve driven by the crankshaft are controlled. The present invention is directed to a control method for an internal combustion engine system including an intake valve closing timing variable mechanism.

When the engine operating state consisting of the engine load and engine speed in the internal combustion engine is in the first operating region on the high load low speed side, in each cylinder cycle, the maximum charging at which the air charging amount becomes maximum at the engine speed. and later closing step that closes the intake valve in the retarded-closing range is set to lag the closing timing, the second operating region of low load or high-speed side than the engine operating state is the first operating region when in, in each cylinder cycle, the early closing step you close the intake valve in the early closing range spaced from the set and the retarded-closing range on the advance side with respect to the highest filling valve closing timing, the first When there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, the engine operation state in the second operation region is changed from the engine operation state in the second operation region within a predetermined period. Engine operating condition A re-transition determination step for determining whether or not the possibility that there is a re-transfer request is greater than or equal to a predetermined level, and when it is determined that the possibility is less than the predetermined level, the closing timing of the intake valve is A transition control step of controlling the intake valve closing timing variable mechanism so as to shift from the slow closing range to the early closing range, and temporarily driving the throttle valve in the closing direction, and the possibility is the predetermined level. And a transition prohibiting step for controlling the intake valve closing timing variable mechanism so that the valve closing timing of the intake valve remains in the delayed closing range when it is determined as described above.

  According to this control method, when the engine operating state of the internal combustion engine is in the first operating region on the high load low speed side, the intake valve closing timing is set within the slow closing range, while the engine operating state of the internal combustion engine is The intake valve closing timing is set within the early closing range separated from the late closing range when the load is in the second operating range at a lower load or higher speed than the first operating range. Further, when the intake valve closing timing shifts between the late closing range and the early closing range, the throttle valve is temporarily driven in the closing direction, and the cylinder air filling amount decreases. This suppresses the occurrence of abnormal combustion such as pre-ignition, suppresses the mechanical loss of the valve train in the low and medium load operation region, and fills the cylinder air against the rapid increase in engine speed in the high load operation region. A sufficient amount can be secured.

  Here, in the control method of the present invention, when there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, the second operation is performed within a predetermined period. When the possibility that there is a request for re-transition from the engine operation state of the region to the engine operation state of the first operation region is equal to or higher than a predetermined level, the intake valve is closed so that the closing timing of the intake valve is stopped in the late closing range. The valve closing timing variable mechanism is controlled. As a result, the closing drive of the throttle valve accompanying the transition of the intake valve closing timing from the late closing range to the early closing range is also prohibited. Thereby, repetitive opening / closing operations of the throttle valve can be suppressed. Therefore, the cylinder air filling amount can be accurately predicted based on the opening degree of the throttle valve.

  According to a second aspect of the invention, in the first aspect of the invention, the internal combustion engine is mounted on a vehicle, and the re-transition determination step includes a wheel slip amount detection step of detecting a slip amount of a wheel of the vehicle. The re-transition determination step includes the wheel slip amount detection step when there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region. When the detected slip amount is less than the predetermined amount, it is determined that the possibility is less than the predetermined level, and the slip amount detected in the wheel slip amount detection step is equal to or greater than the predetermined amount. Is a step of determining that the possibility is equal to or higher than the predetermined level.

  According to this, the possibility can be easily determined in a vehicle having a traction control (TRC (Traction Control) control function), that is, in a vehicle having a TRC control function, the wheel slip amount is limited. When the amount exceeds the predetermined value, the engine torque (load of the internal combustion engine) is temporarily reduced to recover the wheel grip force, and then the engine torque is recovered after the wheel grip force is recovered. .

  Therefore, in this type of vehicle, even when there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, There is a high possibility that there is a request for re-transition from the engine operating state in the second operating region to the engine operating state in the first operating region within the predetermined time.

  In the present invention, paying attention to this, when there is a request for transition from the engine operating state in the first operating region to the engine operating state in the second operating region, the wheel slip amount detecting step detects it. When the slip amount is not less than a predetermined amount, it is determined that the possibility of the re-transfer request is not less than a predetermined level.

  As a result, the determination can be performed easily and reliably, and as a result, the repeated opening / closing operation of the throttle valve is reliably suppressed, and the prediction accuracy of the cylinder air filling amount is improved as much as possible. Can do.

  In the invention of claim 3, in the invention of claim 1 or 2, the vehicle is provided with an accelerator pedal operated by an occupant, and the re-transition determination step includes information on the depression amount of the accelerator pedal. It is assumed that this is a step of acquiring and determining the possibility based on the acquired information.

According to this, in the ascent determination step, the above possibility is determined based on the information related to the depression operation of the accelerator pedal. Normally, when the amount of depression of the accelerator pedal changes , the engine operation state changes accordingly.As in the present invention, by determining the possibility based on information on the amount of depression of the accelerator pedal, This determination can be performed easily and reliably, and as a result, repetitive opening and closing operations of the throttle valve can be reliably suppressed.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the re-transition determining step includes a time change rate calculating step of detecting a depression amount of the accelerator pedal and calculating a time change rate thereof; A time integral value calculation step of calculating a time integral value obtained by integrating the absolute value of the time change rate calculated by the time change rate calculation step in the period, and the re-transition determination step includes the first transition determination step . When there is a request for transition from the engine operation state in the operation region to the engine operation state in the second operation region, when the time integration value calculated in the time integration value calculation step is less than a predetermined value, while the possibility is determined to be lower than the predetermined level, when the time integral value is the predetermined value or more, be assumed the possibility is step determines that the above-mentioned predetermined level or higher .

According to this, in the time change rate calculating step, the time change rate is calculated with the amount of depression of the accelerator pedal is detected, the time integration value calculation step, a predetermined past the absolute value of the time rate of change from the current The time integration value integrated within the time is calculated. This time integral value is a value related to the operation frequency of the accelerator pedal, and the larger the value, the higher the operation frequency of the accelerator pedal by the occupant, so within a predetermined period, from the engine operation state of the second operation region, It can be said that there is a high possibility that there is a request for re-transition to the engine state in the first operating region.
In the present invention, paying attention to this, when the time integration value is equal to or greater than a predetermined value, it is determined that the possibility that the re-transfer request is present is equal to or higher than a predetermined level. This can be done even more reliably.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the internal combustion engine is mounted on a vehicle, and the vehicle has a gear position based on a predetermined shift characteristic. An automatic transmission is provided that can be set by switching between an auto mode that automatically switches between and a manual mode that switches the gear position based on manual operation by the occupant selection operation,
The automatic transmission further includes a mode determination step for determining which of the automatic mode and the manual mode is set as the setting mode of the automatic transmission, and the re-transition determination step is performed in the first operating region. In a case where there is a request to shift from a certain engine operating state to the engine operating state of the second operating region, it is determined in the mode determining step that the mode of the automatic transmission is set to the auto mode. Sometimes, it is determined that the possibility is less than the predetermined level, whereas when it is determined that the setting mode of the automatic transmission is set to the manual mode, the possibility is determined to be greater than or equal to the predetermined level. It is assumed that the process is

According to this, when there is a request for transition from the engine operating state in the first operating region to the engine operating state in the second operating region, the mode of the automatic transmission is set to the manual mode. Therefore , it is determined that the possibility of the re-migration request is equal to or higher than a predetermined level.

  Usually, when the manual mode is set (selected) as the mode of the automatic transmission, the occupant often aims for sporty running that frequently switches the gear position. Therefore, when the manual mode is set as the automatic transmission mode, there may be a request for re-transition from the engine operation state in the second operation region to the engine state in the first operation region within a predetermined period. It can be said that the nature is high. In the present invention, paying attention to this, the manual mode is set when there is a request for transition from the engine operating state in the first operating region to the engine operating state in the second operating region. In some cases, it is determined that the possibility of re-migration is above a predetermined level. As a result, the determination can be performed more easily and reliably, and as a result, the repeated opening / closing operation of the throttle valve can be reliably suppressed.

In the invention of claim 6, the intake communication passage cylinder defining a combustion chamber with piston reciprocating, the air introduced into the combustion chamber passes, and are driven by the crankshaft, a combustion chamber intake passage An internal combustion engine having a shut-off intake valve, an intake valve closing timing variable mechanism that controls the closing timing of the intake valve, a throttle valve that is openable and closable in the intake passage, and driving the throttle valve An internal combustion engine system including a throttle actuator and a controller that controls the throttle actuator and the intake valve closing timing variable mechanism is an object.

Then, the controller, when the engine operating condition consisting of the engine load and the engine speed in the internal combustion engine is in the first operating region of high load low speed side, in each cylinder cycle, air charge in the engine speed The intake valve closing timing variable mechanism is controlled so as to close the intake valve within a delay closing range set to a retard angle side with respect to the maximum maximum valve closing timing , and the engine operating state is the first operating state. When in the second operating region at a lower load or higher speed than the operating region, in each cylinder cycle, within the early closing range that is set to the advance side with respect to the maximum filling valve closing timing and that is separated from the slow closing range. And when the intake valve closing timing variable mechanism is controlled to close the intake valve , and there is a request to shift from the engine operating state in the first operating region to the engine operating state in the second operating region. In addition, Within the constant period, probably a remigrate request from the engine operating state of the second operating region to the engine operating state of the first operating region is equal to or higher than a predetermined level, and, the possible The intake valve closing timing variable mechanism is controlled so that the closing timing of the intake valve shifts from the slow closing range to the early closing range when the engine performance is determined to be less than the predetermined level, and the throttle When the throttle actuator is controlled so that the valve temporarily operates in the closing direction , and when the possibility is determined to be greater than or equal to the predetermined level, the closing timing of the intake valve is within the delayed closing range. The intake valve closing timing variable mechanism is controlled so as to stay.

  According to this configuration, the same effect as that of the first aspect of the invention can be obtained.

As described above, according to the present invention, when the engine operating state of the internal combustion engine is in the first operating region on the high load low speed side, the intake valve closing timing is set within the slow closing range, while the engine operating state is The intake valve closing timing is set within the early closing range when the load is lower than the first operating range or in the second operating range on the high speed side, and the intake valve closing timing is set from the late closing range to the early closing range. When shifting to, the throttle valve is temporarily driven in the closing direction, and there is a request to shift from the engine operating state in the first operating region to the engine state in the second operating region. In this case, after that, it is determined whether or not there is a request for re-transition from the second operation region to the first operation region within a predetermined period, and when this possibility is greater than or equal to a predetermined level, the closing timing of the intake valve By keeping it in the slow closing range, While preventing the occurrence of abnormal combustion in the mixed air in the cylinder, it is possible to improve the fuel efficiency of the internal combustion engine by reducing the mechanical loss and pumping loss of the valve operating system.

1 is a schematic configuration diagram showing an internal combustion engine system including an engine control unit as a control device according to an embodiment of the present invention. It is a perspective view which shows the intake valve drive mechanism of an engine (internal combustion engine). It is sectional drawing which shows the principal part of an intake valve drive mechanism, (A) shows when the valve lift amount is 0 in the large lift control state, and (B) shows when the valve lift amount is maximum in the large lift control state. (C) shows when the valve lift amount is 0 in the small lift control state, and (D) shows when the valve lift amount is maximum in the small lift control state. It is a figure which shows the example of control of an intake valve drive mechanism. It is a flowchart which shows the example of control of the engine in an engine control unit. It is a flowchart which shows the example of control of the engine in an engine control unit. It is a flowchart which shows the example of control of the engine in an engine control unit. It is a flowchart which shows the traction control control in an engine control unit. It is a flowchart which shows the setting process of the mode transition prohibition flag in an engine control unit. It is a figure which shows an example of the engine control map memorize | stored in memory. It is a figure which shows the example of control of the intake valve closing timing in the early closing mode. It is a figure which shows the example of control of the throttle opening in an early closing mode. 6 is a timing chart showing an example of control of intake valve closing timing, throttle opening, and EGR valve opening in the retard transition mode. It is a figure which shows the example of control of the intake valve closing timing in slow closing mode, (A) is a case where throttle opening is controlled in parallel with control of an intake valve, (B) is maintaining throttle opening constant. Is the case. It is a figure which shows the example of control of the throttle opening in late closing mode, (A) is a case where the throttle opening is controlled in parallel with the control of the intake valve, (B) is a case where the throttle opening is kept constant Indicates. 6 is a timing chart showing an example of control of intake valve closing timing, throttle opening, and EGR valve in an advance angle transition mode. FIG. 5 shows an example of control when the flowcharts of FIGS. 5 to 7 are executed in the engine control unit. FIG. 5A shows a case where the throttle opening is controlled in parallel with the control of the intake valve, and FIG. The case where it is maintained constant is shown. It is explanatory drawing for demonstrating the calculation method of the accelerator opening integrated value used when setting the mode transition prohibition flag in an engine control unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an internal combustion engine system S including an engine control unit 100 as a control device according to an embodiment of the present invention.

  The internal combustion engine system S includes an engine (internal combustion engine) 1, various actuators associated with the engine 1, and various sensors, and the engine control unit 100 controls each actuator based on signals from the sensors. To do.

The engine 1 is a spark ignition type internal combustion engine, and includes the first to fourth four cylinders 11. However, the number of the cylinders 11 is not limited to four. The engine 1 is mounted on a vehicle such as an automobile, and its crankshaft 14 is connected to drive wheels via an automatic transmission (AT) to propel the vehicle. As a driving system of the vehicle, the FF system is adopted, and the front wheels are driving wheels and the rear wheels are driven wheels. The automatic transmission switches the gear position by manually operating a shift lever installed between the driver seat and the passenger seat, and an automatic mode in which the gear position is automatically switched based on a preset gear shift characteristic. It is configured to be able to switch between two shift modes, the manual mode. In this embodiment, the shift mode is switched by the driver operating the mode switch to select a desired shift mode. A mode change switch (not shown) outputs the shift mode information selected by the driver to the engine control unit 100 described later.

The engine 1, 13: have one or more geometric compression ratio, the geometric compression ratio is 14: 1 to 16: is preferably 1 or less. A large geometric compression ratio means that the expansion ratio is large. Therefore, the engine efficiency increases as the geometric compression ratio increases. Therefore, in the present embodiment, the geometric compression ratio is set to 13 or more, and the high torque and the fuel consumption are significantly reduced while avoiding knocking by a method such as ignition retard.

  The higher the compression ratio, the higher the possibility of abnormal combustion, so the effective compression ratio needs to be reduced, that is, the cylinder air charge needs to be reduced. If so, the output obtained for the cylinder volume decreases, and the efficiency when viewed in terms of the weight ratio of the engine decreases. On the other hand, when the engine 1 is mounted on a vehicle such as an automobile, a problem arises in mountability in the engine room. Therefore, the upper limit of the geometric compression ratio is preferably 16: 1 or less.

  The engine 1 includes a cylinder block 12 and a cylinder head 13 mounted thereon, and a cylinder 11 is formed therein. As is well known, a crankshaft 14 is rotatably supported on the cylinder block 12 by a journal, a bearing or the like, and this crankshaft 14 is connected to a piston 15 via a connecting rod 16.

  The piston 15 is slidably inserted into each cylinder 11 to define a combustion chamber 17. Although only one is shown in the figure, the cylinder head 13 is formed with two intake ports 18 for each cylinder 11 in the cylinder head 13 and communicates with the combustion chamber 17. Similarly, in the cylinder head 13, two exhaust ports 19 are formed in the cylinder head 13 for each cylinder 11 and communicate with the combustion chamber 17. As shown in the figure, the intake valve 21 and the exhaust valve 22 are disposed so that the intake port 18 and the exhaust port 19 can be shut off (closed) from the combustion chamber 17, respectively. The intake valve 21 is driven by an intake valve drive mechanism 30 as a valve operating device, and the exhaust valve 22 is driven by an exhaust valve drive mechanism 40 to reciprocate at a predetermined timing to open and close the intake port 18 and the exhaust port 19. To do.

  The intake valve drive mechanism 30 has an intake camshaft 31, and the exhaust valve drive mechanism 40 has an exhaust camshaft 41. The camshafts 31 and 41 are connected by the crankshaft 14 via a power transmission mechanism such as a known chain / sprocket mechanism. As is well known, the power transmission mechanism is configured such that the camshafts 13 and 41 rotate once while the crankshaft 14 rotates twice.

The phase angle of the camshaft is detected by the cam phase sensor 35 and its detection signal θ _{VCT_A}
Is input to the engine control unit 100.

The spark plug 51 is attached to the cylinder head 13 by a known structure such as a screw. Ignition system 52 receives a control signal SA _D from the engine control unit 100, as the spark plug 51 generates a spark at a desired ignition timing, energizing it.

  The fuel injection valve 53 is attached to one side (in the illustrated example, the intake side) of the cylinder head 13 with a known structure, for example, using a bracket. The tip of the fuel injection valve 53 is positioned below the two intake ports 18 in the vertical direction and is positioned in the middle of the two intake ports 18 in the horizontal direction and faces the combustion chamber 17.

Although not shown, the fuel supply system 45 includes a high-pressure pump that boosts and supplies fuel to the fuel injection valve 53, piping and hoses that supply fuel from the fuel tank to the high-pressure pump, and the fuel injection valve 53. And an electric circuit to be driven. This electric circuit receives a control signal FP _D from the engine control unit 100 and operates a solenoid of the fuel injection valve 53 to inject a predetermined amount of fuel from the injection valve 53 at a predetermined timing.

The intake port 18 communicates with the surge tank 55 a through an intake path 55 b in the intake manifold 55. An intake air flow from an air cleaner (not shown) passes through the throttle body 56 and is supplied to the surge tank 55a. A throttle valve 57 is disposed on the throttle body 56. As is well known, the throttle valve 57 throttles the intake air flow toward the surge tank 55a and adjusts its flow rate. Throttle actuator 58 receives a control signal TVO _D from the engine control unit 100, adjusts the opening of the throttle valve 57.

  The exhaust port 19 communicates with a passage in the exhaust pipe as is well known by an exhaust path in the exhaust manifold 60. An exhaust gas purification system having one or more catalytic converters 61 is disposed in the exhaust passage downstream of the exhaust manifold 60. The catalytic converter 61 can be a well-known three-way catalyst, lean NOx catalyst, oxidation catalyst, or the like, and any other type of catalyst as long as it meets the purpose of exhaust gas purification by a specific fuel control technique. It may be.

Further, in order to circulate a part of the exhaust gas to the intake system (to perform EGR (Exhaust Gas Recirculation)), an EGR pipe is provided between the intake manifold 55 (downstream of the throttle valve 57) and the exhaust manifold 60. 62 is connected. Since the pressure on the exhaust side is higher than that on the intake side, a part of the exhaust gas (EGR gas) flows into the intake manifold 55 and is mixed with fresh air drawn from the intake manifold 55 into the combustion chamber 17. The EGR pipe 62 is provided with an EGR valve 63 for adjusting the flow rate of the EGR gas. The EGR valve actuator 64 receives the control signal EGR _OPEN from the engine control unit 100 and adjusts the opening degree of the EGR valve 63.

  The engine control unit 100 is a controller based on a well-known macro computer. The engine control unit 100 is a central processing unit (CPU) that executes a program, a memory that is composed of, for example, a RAM or a ROM and stores programs and data, And an input / output (I / O) bus for inputting and outputting signals.

The engine control unit 100 receives the shift mode signal from the automatic transmission, the intake air flow AF from the air flow sensor 71, the intake manifold pressure MAP from the intake pressure sensor 72, the crank angle pulse signal from the crank angle sensor 73, and the exhaust gas from the oxygen concentration sensor 74. The oxygen concentration EGO of the vehicle, the accelerator opening signal α from the accelerator opening sensor 75 that detects the amount of depression of the accelerator pedal, the vehicle speed signal VSP from the vehicle speed sensor 76 that detects the rotational speed of the output shaft of the automatic transmission, Various inputs such as a wheel speed signal Vw from the wheel speed sensor 77 are accepted.

The engine control unit 100 controls the operation of the engine 1 based on the input as described above. At that time, when the slip amount V _SLIP of the drive wheel (front wheel) exceeds a predetermined slip amount V _set that is set in advance, the engine control unit 100 executes traction control control (hereinafter referred to as TRC control) described later. Thus, the engine output is controlled so that the slip amount V _SLIP of the drive wheel becomes the target slip amount.

Specifically, the engine control unit 100 determines the engine speed N _ENG , wheel slip amount V _SLIP , desired throttle opening TVO, fuel injection amount FP, ignition timing SA, valve phase angle θ based on the above inputs. Control parameters such as _VCT and EGR amount (EGR valve opening) Q _EGR are calculated. Based on these control parameters, the throttle opening signal TVO _D , the fuel injection pulse signal FP _D , the ignition pulse signal SA _D , the valve phase angle signal θ _{VCT_D} , and the EGR opening signal EGR _OPEN are respectively converted into the throttle actuator 58 and the fuel. The power is output to the supply system 54, the ignition system 52, the variable valve timing mechanism (VCT mechanism) 32, the EGR valve actuator 64, and the like.

  Next, the details of the intake valve drive mechanism 30 according to the present embodiment will be described with reference to FIG. FIG. 2 is a perspective view showing a specific configuration of the intake valve drive mechanism 30 according to the embodiment of FIG. 1, and FIG. 3 is a cross-sectional view showing a main part of the intake valve drive mechanism 30 of FIG. 3, (A) shows when the valve lift amount is 0 in the large lift control state, (B) shows when the valve lift amount is maximum in the large lift control state, and (C) shows the small lift control state. In FIG. 2, the valve lift amount is 0, and (D) shows the maximum valve lift amount in the small lift control state.

  The intake valve drive mechanism 30 of this embodiment includes a variable valve timing mechanism 32, and the variable valve timing mechanism 32 is connected to and driven by the crankshaft 14 via a chain drive mechanism. In addition to the driven sprocket 104, the chain drive mechanism includes a drive sprocket of the crankshaft 14 and a chain wound around both the sprockets (not shown).

  The VCT mechanism 32 includes a case fixed to the driven sprocket 104 so as to rotate integrally, and a rotor accommodated in the case and fixed to the inner shaft 105 so as to rotate integrally. Between the case and the rotor, a plurality of hydraulic chambers are formed side by side (in the circumferential direction) around the central axis X (see FIG. 3). Then, the liquid pressurized by the pump (for example, engine oil) is selectively supplied to each hydraulic pressure chamber to form a pressure difference between the hydraulic pressure chambers facing each other.

Then, the engine control unit 100 outputs a control signal θ _{VCT_D} to the electromagnetic valve 32a of the VCT mechanism 32, and the electromagnetic valve 32a performs duty control of the hydraulic pressure in response to the control signal θ _{VCT_D.} Adjust the flow rate and pressure of the liquid supplied to the chamber. This changes the phase difference between the sprocket 104 and the inner shaft 105, thereby achieving the desired rotational phase of the inner shaft 105 as is well known.

  As shown in FIGS. 3A to 3D, the inner shaft 105 has a disc-shaped cam 106 provided integrally with each cylinder 11. The cam 106 is provided eccentrically from the axis of the inner shaft 105 and rotates at a phase defined by the VCT mechanism 32. The inner periphery of the ring-shaped arm 107 is rotatably fitted to the outer periphery of the eccentric cam 106. When the inner shaft 105 rotates around its central axis, the ring-shaped arm 107 revolves around the same central axis X. While rotating around the central axis of the eccentric cam 106.

  The inner shaft 105 is provided with a rocker connector 110 for each cylinder 11. The rocker connector 110 has a cylindrical shape, and is externally inserted into the inner shaft 105 and is coaxially supported. In other words, the rocker connector 110 is rotatably supported around the central axis C. Is a bearing journal, and is rotatably supported by a bearing cap (not shown) disposed on the cylinder head 13.

  The rocker connector 110 is integrally provided with first and second rocker cams 111 and 112. Since both configurations are the same, FIGS. 3A to 3D show only the rocker cam 111. The rocker cam 111 has a cam surface 111a and a circumferential base surface 111b (see FIG. 3D), both of which are in sliding contact with the upper surface of the tappet 115. The rocker cam 111 presses the tappet 115 to open the intake valve 21 like the cam of a general intake valve drive mechanism except that it does not rotate continuously and swings. Yes. The tappet 115 is supported by a valve spring 116, and the valve spring 116 is supported between the cages 117 and 118 as is well known.

  As shown in FIG. 2, the control shaft 120 is disposed above the inner shaft 105 and the rocker cam parts 110 to 112 along with the assembly thereof. The control shaft 120 is rotatably supported by a bearing (not shown), and a coaxial worm gear 121 protruding from the outer peripheral surface is integrally provided near the center in the longitudinal direction.

The worm gear 121 meshes with the worm 122. The worm 122 is fixed to an output shaft of a stepping motor 123 that is an actuator of a variable valve lift mechanism (VVL). Therefore, the control shaft 120 can be rotated to a desired position by the operation of the stepping motor 123 that receives the control signal (valve lift amount signal) θ _{VVL_D} from the engine control unit 100. In this way, the control arm 131 for each cylinder 11 is attached to the control shaft 120, and these control arms 131 are integrally rotated by the rotation of the control shaft 120.

  Further, the control arm 131 thus rotated is connected to the ring-shaped arm 107 by a control link 132. That is, one end of the control link 132 is rotatably connected to the tip of the control arm 131 by the control pivot 133, and the other end of the control link 132 is rotatably connected to the ring-shaped arm 107 by the common pivot 134. Yes.

  Here, the common pivot 134 connects the other end of the control link 132 to the ring-shaped arm 107 as described above, and penetrates the ring-shaped arm 107 so that it can also rotate to one end of the rocker link 135. It is linked to. The other end of the rocker link 135 is rotatably connected to the rocker cam 111 by a rocker pivot 136, whereby the rotation of the ring-shaped arm 107 is transmitted to the rocker cam 111.

  More specifically, when the inner shaft 105 rotates and the eccentric cam 106 rotates integrally therewith, as shown in FIGS. 3A and 3C, the eccentric cam 106 is positioned relatively downward. For example, the ring-shaped arm 107 is also positioned on the lower side. On the other hand, if the eccentric cam 106 is positioned relatively on the upper side as shown in FIGS. Come to be located.

  At this time, the position of the common pivot 134 that connects the ring-shaped arm 107 and the control link 132 is a three-way positional relationship between the position of the control pivot 133 and the common center position of the eccentric cam 106 and the ring-shaped arm 107. Therefore, if the position of the control pivot 133 does not change as shown in the figure (the control shaft 120 does not rotate), the common pivot 134 rotates around the common center of the eccentric cam 106 and the ring-shaped arm 107. In response to only this, the reciprocating operation is substantially performed in the vertical direction.

  Such reciprocating motion of the common pivot 134 is transmitted to the first rocker cam 111 by the rocker link 135, and the first rocker cam 111 is coupled with the second rocker cam 112 connected by the rocker connector 110 to the central shaft. Swing around X. As shown in FIGS. 3B and 3C, the rocker cam 111 that swings in this manner resists the tappet 115 against the spring force of the valve spring 116 while the cam surface 111 a contacts the upper surface of the tappet 115. The tappet 115 pushes down the intake valve 21 to open the intake port 18.

  On the other hand, as shown in FIGS. 3A and 3D, when the base surface 111b of the rocker cam 111 contacts the upper surface of the tappet 115, the tappet 115 is not pushed down. This is because the radius of the base surface 111 b of the rocker cam 111 around the central axis X is set to be equal to or smaller than the distance between the central axis X and the upper surface of the tappet 115.

  If the position of the control pivot 133 changes in the mutual positional relationship between the control pivot 133, the common pivot 134, and the common center of the eccentric cam 106 and the ring-shaped arm 107 as described above, the three-way position can be changed. The relationship changes, and the common pivot 134 reciprocates along a path different from the above.

  Therefore, the swing range of the rocker cams 111 and 112 can be changed by rotating the control shaft 120 and the control arm 131 by the operation of the motor 123 and changing the position of the control pivot 133. For example, when the control arm 131 is rotated clockwise in FIG. 3 and the control pivot 133 is shifted from the position shown in FIG. 3A to the upper left side as shown in FIG. The swing range has a relatively strong tendency that the base surface 111b contacts the upper surface of the tappet 115.

Figure 4 shows the operation setting of the intake valve 21 by the intake valve driving mechanism 30 according to this embodiment, the valve lift theta _VVL of the intake valve 21, for example in the range from theta _{VVL_min} to theta _{VVL_max,} to each cylinder 11 The valve closing timing of the intake valve 21 is controlled so as to be retarded in the range of θ _{VCT_min} to θ _{VCT_max} according to the increase of the valve lift amount θ _VVL. Be controlled. The valve opening timing and the valve closing timing of the intake valve 21 can be combined in any way as necessary. For example, a so-called lost motion operation in which the valve lift amount is zero is also possible.

In the present embodiment, for example, when the intake valve 21 is opened and closed in the intake stroke when the engine speed (engine speed) N _ENG is 1500 rpm, in the present embodiment, the valve opening timing of the intake valve 21 is almost the operation range. Thus, the valve opening is started immediately before the exhaust top dead center (crank angle, for example, BTDC 20 ° CA), and the valve closing timing of the intake valve 21 is changed in accordance with the required torque of the engine 1.

Here, in the present embodiment, the closing timing of the intake valve 21 in the cylinder cycle is the timing at which the air charge amount becomes maximum at the engine speed (engine speed) N _ENG in the cylinder cycle (hereinafter referred to as the maximum charging valve closing). A first valve closing timing range IVC _1st set to an advance side with respect to the timing) and a second valve closing timing range IVC _1st set to a retard angle side with respect to the maximum filling valve closing timing and separated from the first valve closing timing range IVC _1st The valve closing timing range IVC _2nd is set. Thus, the first and second valve closing timing ranges are set with the maximum filling valve closing timing in between, and are not necessarily set on the basis of the intake bottom dead center.

The engine 1 is operated so that the intake valve 21 is closed in the first valve closing timing range IVC _1st and the early closing mode M _EIVC is _operated, and the intake valve 21 is closed in the second valve closing timing range IVC _2nd. Delayed operation mode M _LIVC , advance mode M _TR-A for shifting operation mode M from delayed operation mode M _LIVC to early operation mode M _EIVC , and operation mode M from early operation mode M _EIVC It is possible to selectively switch to the retarded angle transition mode M _TR-R for shifting to the delayed closing mode _MLIVC .

The early closing mode M _EIVC is a mode selected when the load is low. In the early closing mode M _EIVC , the valve lift amount θ _VVL of the intake valve 21 is set to be relatively small, and the intake valve closing _timing is set in accordance with the valve lift amount θ _VVL in the advance side of the intake bottom dead center, for example. To set.

The slow closing mode M _LIVC is a mode selected at the time of high load. In the slow closing mode M _LIVC , the valve lift amount θ _VVL of the intake valve 21 is set to be relatively large, and the intake valve closing _timing is set in accordance with the valve lift amount θ _VVL in a range that is, for example, retarded from the intake bottom dead center. To set.

In the present embodiment, as described above, the second valve closing timing range IVC _2nd in which the slow closing mode M _LIVC is set is greater than the first valve closing timing range IVC _1st in which the early closing mode M _EIVC is set. Are also retarded and spaced apart. Thus, both the closing timing range IVC _1st, Between IVC _2st, so that the intermediate closing timing range IVC _IM is set.

  Next, the reason why the operation mode M as described above is set will be described. That is, in order to increase the output of the engine 1 and increase the expansion ratio in order to reduce fuel consumption, while suppressing the occurrence of abnormal combustion, the closing timing of the intake valve 21 is set to be higher than the maximum filling valve closing timing. It is preferable to advance or retard to lower the effective compression ratio.

When the operation control of the engine 1 is early closing system for advanced from the maximum filling closing timing of the closing timing of the intake valve 21, as shown in FIG. 3 (C), (D) , the rocker cam 111 Is relatively small, and the resistance of the valve spring 116 is also small, which is preferable from the viewpoint of reducing mechanical loss of the valve operating system. However, as the required load of the engine 1 increases and the engine speed increases, the closing timing of the intake valve 21 for obtaining the necessary cylinder air filling amount is rapidly retarded. In addition, as the engine speed increases, the possibility of abnormal combustion decreases due to an increase in the fluidity of the air-fuel mixture in the cylinder, so the amount of restriction on the advance side of the target intake valve closing timing decreases. . Therefore, it is necessary to retard the closing timing of the intake valve 21 rapidly as the engine speed increases. However, due to the response delay of the intake valve drive mechanism 30, the closing timing of the intake valve 21 may be shifted to the advance side with respect to the target closing timing, and the cylinder air filling amount may be insufficient. When the valve closing timing is set to be retarded from the maximum filling valve closing timing, air is introduced into the cylinder 11 until the piston 15 moves to the bottom dead center, and the piston exceeds the bottom dead center. After turning upward, the air in the cylinder is returned to the intake passage. For this reason, an effective compression ratio can be reduced. However, in this case, it is necessary to set the valve lift amount and valve operating range of the intake valve 21 to the maximum values (see FIG. 4), and there is a concern that the mechanical loss of the valve operating system increases.

Therefore, in the present embodiment, the intake valve closing timing is set to the first valve closing timing range IVC _1st in the low load to medium load operation region, while the intake valve closing timing is set to the first valve closing timing in the high load operation region. The second valve closing timing range IVC _2nd, which is separated from the timing range IVC _1st, is set, so that a sufficient air filling amount is ensured in a high load operation region while suppressing mechanical loss as much as possible. When the intake valve closing timing is shifted between the first valve closing timing range IVC _1st and the second valve closing timing range IVC _2nd , the throttle valve 57 is temporarily driven in the closing direction during the shift. Thus, the occurrence of abnormal combustion is suppressed.

  Next, an example of control of the engine 1 in the engine control unit 100 will be specifically described with reference to the flowcharts of FIGS.

First, in step S1, initialization of various settings is first executed. By this initialization, the current operation mode M is set to the early closing mode M _EIVC .

In step S2, the accelerator opening signal α from the accelerator opening sensor 75, the engine speed N _ENG based on the crank angle pulse signal, and the vehicle speed signal VSP from the vehicle speed sensor 76 are read, and the target torque is based on the read information. TQ is calculated.

In step S3, the fuel injection amount FP (or air / fuel ratio), the target air filling amount CE, the EGR amount Q _EGR , and the ignition timing SA are calculated based on the target torque TQ and the engine speed N _ENG .

In step S4, the data of the control map M1 (see FIG. 10) stored in the memory in advance is read, and the current operation region R of the engine 1 is determined based on the control map M1. In the control map M1, as shown in FIG. 10, two characteristic lines L1 and L2 in which the target air filling amount CE and the engine speed N _ENG are in a proportional relationship are drawn, and these two characteristic lines are drawn. Three operation areas R _LIVC , R _TR , and R _EIVC partitioned by L1 and L2 are set. In step S4, the operation regions R _LIVC , R _TR , and R _EIVC corresponding to the engine speed N _ENG and the target air charge amount CE calculated in step S3 are _set as the current operation region R of the engine 1. judge.

When the operation region R is the operation region R _LIVC on the high load low rotation side that is equal to or higher than the characteristic line L1 (hereinafter referred to as the slow closing operation region R _LIVC ), the operation mode M is set to the slow closing mode M _LIVC . In the case of the operation region R _EIVC on the low load and high rotation side below the characteristic line L2 (hereinafter _{referred to} as the early closing operation region R _EIVC ), the operation mode M is set to the early closing mode M _EIVC and the operation region R but if there is a transient region R _TR between the characteristic line L1 and the characteristic line L2, controls the operation mode M to the hysteresis, even higher demand load from operating range R _EIVC, the characteristic line L1 The operation mode M is maintained at the early closing mode M _EIVC until the operation line M is exceeded, and the operation mode M is maintained at the slow closing mode M _LIVC until the characteristic line L2 is exceeded even if the required load is reduced from the operation region R _LIVC. .

In step S5, it is determined whether or not the current operation mode M is the early closing mode M _EIVC . If this determination is NO, the process proceeds to step S51 (see FIG. 6), whereas if it is YES, the process proceeds to step S6. .

In step S6, the current operation region R of the engine 1 is outside the slow closing operation region _RLIVC , that is, the valve closing timing range IVC of the intake valve 21 based on the required load is other than the second valve closing timing range IVC _2nd. When this determination is NO, the process proceeds to step S10, and when it is YES, the process proceeds to step S7.

In step S7, the current operation mode M is set to the early closing mode _MEIVC .

In step S8, the valve lift amount θ _{VVL of} the intake valve 21, the valve opening period θ _VCT of the intake valve 21, and the throttle opening TVO are _{calculated based} on the target air filling amount CE and the engine speed N _ENG in the early closing mode M _EIVC. calculate.

In step S9, the control signal corresponding to the valve lift amount θ _VVL calculated in step S8, the valve opening period θ _VCT , the throttle opening TVO, the fuel injection amount FP, the EGR amount Q _EGR calculated in step S3, and the ignition timing SA. FP _D, EGR _OPEN, by outputting the _{SA D, θ VV-D,} θ VCT-D, TVO D, to control the actuator such as the intake valve driving mechanism 30 and the throttle valve 57, and thereafter, the flow returns to step S2 .

In step S10 the determination in step S 6 is advanced when it NO, the setting the operation mode M to the retard transition mode M _TR-R.

In step S11, a predetermined count time C _TR-R is set as the count value C _TR . The predetermined count time C _TR-R is provided until the closing timing of the intake valve 21 by the intake valve drive mechanism 30 is switched, so that the filling amount is temporarily reduced so that an abnormality such as pre-ignition occurs. This is to avoid combustion.

In step S12, the valve lift amount θ _{VVL of} the intake valve 21 and the valve opening period θ _VCT and EGR of the intake valve 21 are determined based on the target air filling amount CE and the engine speed N _ENG in the retard angle transition mode M _TR-R. The amount Q _EGR and the throttle opening TVO are calculated, and then the process proceeds to step S9.

In step S51 (see FIG. 6) that proceeds when the determination in step S5 is NO, it is determined whether or not the current operation mode M is the slow closing mode M _LIVC . If this determination is NO, step S59 ( On the other hand, if YES, the process proceeds to step S52.

In step S52, it is determined whether or not the current operation region R is the early closing operation region R _EIVC . When this determination is NO, the process proceeds to step S63, and when it is YES, the process proceeds to step S53.

  In step S53, it is determined whether or not the TRC control is being executed. When this determination is YES, the process proceeds to step S64, and when it is NO, the process proceeds to step S54.

In step S54, it is determined whether or not the value of the mode transition prohibition flag F _SPRT is 1. When this determination is YES, the process proceeds to step S64, and when it is NO, the process proceeds to step S55.

  In step S55, it is determined whether or not the manual mode is set as the transmission mode of the transmission. When this determination is YES, the process proceeds to step S64, and when it is NO, the process proceeds to step S56.

In step S56, the operation mode M of the engine 1 is set to the retarded-closing mode to switch from M _LIVC the earlier closing mode M _EIVC advance transition mode M _TR-A.

In step S57, a predetermined count time C _TR-A is set as the count value C _TR .

In step S58, the valve lift amount θ _{VVL of} the intake valve 21 and the valve opening period θ _VCT of the intake valve 21 based on the target air filling amount CE and the engine speed N _ENG in the advance transition mode M _TR-A , The EGR amount Q _EGR and the throttle opening TVO are calculated, and then the process proceeds to step S9.

In step S59 (see FIG. 7) that proceeds when the determination in step S51 is NO, the count value is decremented as count value C _TR = C _TR −1.

In step S60, it is determined whether or not the current operation mode M is the advance transition mode M _TR-A . When this determination is NO, the process proceeds to step S62, and when it is YES, the process proceeds to step S61.

In step S61, it is determined whether or not the count value _CTR is greater than 0. When this determination is NO, the process proceeds to step S7, and when it is YES, the process proceeds to step S58.

In step S62, it is determined whether or not the count value _CTR is greater than 0. When this determination is NO, the process proceeds to step S63, and when it is YES, the process proceeds to step S12.

In step S63, which proceeds when the determination in step S52 is NO, the operation mode M of the engine 1 is set to the slow closing mode _MLIVC .

In step S64, the valve lift amount θ _{VVL of} the intake valve 21, the valve opening period θ _VCT of the intake valve 21, and the throttle opening are based on the target air filling amount CE and the engine speed N _ENG in the slow closing mode M _LIVC. TVO is calculated, and then the process proceeds to step S9.

If any of steps S53 to S55 is YES, the process proceeds to step S64 in any case (details will be described later).

  Next, the TRC control in the engine control unit 100 will be specifically described with reference to the flowchart of FIG.

  In the first step S101, the detection signals from the respective sensors are read in the same manner as in step S1.

In step S102, the speed of each wheel is obtained based on the wheel speed signal Vw from the wheel speed sensor 77 of each wheel among the detection signals read in step S101, and the driven wheel is determined from the speed _Vf of the driving wheel (front wheel). A value obtained by subtracting the (rear wheel) speed V _r is calculated as the slip amount V _SLIP .

In step S103, it is determined whether or not the slip amount V _SLIP calculated in step S102 is equal to or less than the predetermined slip amount V _set . If this determination is YES, the process returns. If NO, the process proceeds to step S104.

  In step S104, a program necessary to execute TRC control is called and executed.

In step S105, a torque down amount ΔTQ (target reduction amount of engine torque) necessary for controlling the slip amount V _SLIP of the drive wheels to the target slip amount is calculated.

  In step S106, the target torque TQ of the engine 1 is calculated based on the torque down amount ΔTQ calculated in step S105. Then, a necessary control signal is output to each actuator so that the engine torque matches the target torque TQ, and then the process returns.

Next, the setting / updating process of the mode transition prohibition flag F _SPRT in the engine control unit 100 will be specifically described with reference to the flowchart of FIG.

In the first step S201, similarly to step S1 01, reads the detection signals from the sensors.

In step S202, the time change rate (time differential value) of the accelerator opening signal α from the accelerator opening sensor 75 is obtained and its absolute value (= | dα / dt | = D) is calculated. Specifically, a change amount Δα of the read accelerator opening signal α from the previous reading and an elapsed time Δt from the previous reading of the accelerator opening signal α to the current reading are obtained, and D = | Δα / Δt | may be calculated. The accelerator opening signal α is a voltage value signal, and the value of the accelerator opening signal α increases as the amount of depression of the accelerator pedal by the occupant increases.

In step S203, the time integral value I (= ∫ | dα / dt | dt) of the D value within the past predetermined time (for example, within the past 4 seconds) up to the present is calculated.

In step S204, it is determined whether or not the time integral value I calculated in step S203 is less than a predetermined threshold value _Iset . When this determination is YES, the process proceeds to step S207, and when it is NO, the process proceeds to step S205.

In step S205, it is determined whether or not the value of the mode transition prohibition flag F _SPRT is 1. When this determination is YES, the process returns, while when it is NO, the process proceeds to step S206.

In step S206, the mode transition prohibition flag F _SPRT is set to 1, and then the process returns.

In step S207, which proceeds when the determination in step S204 is YES, it is determined whether or not the mode transition prohibition flag F _SPRT is 0. If this determination is YES, the process returns. If NO, the process returns to step S208. move on.

In step S208, the value of the mode transition prohibition flag F _SPRT is set to 0, and then the process returns.

  Hereinafter, the setting of the control parameters (intake valve closing timing, throttle opening TVO, etc.) of the engine 1 in each mode described in the above flowchart will be described in detail.

FIG. 11 shows an example of control of the intake valve closing _timing in the early closing mode _MEIVC . In the control example shown in the figure, the engine control unit 100 operates when the operation region R of the engine 1 is operated in a region other than the slow-close operation region R _LIVC , that is, the closing timing of the intake valve 21 is the first closed. When the valve timing range IVC _1st is set, the closing timing of the intake valve 21 is retarded as the engine speed N _ENG increases. Further, the valve closing timing of the intake valve 21 is retarded as the target air filling amount CE increases. Therefore, when the closing timing of the intake valve 21 is set within the first closing timing range IVC _1st , the air filling amount CE is increased by delaying the closing timing of the intake valve 21. The torque commensurate with the required torque can be output.

FIG. 12 shows a control example of the throttle valve 57 in the early closing mode _MEIVC .

  In the control example shown in the figure, a characteristic line L3 parallel to the characteristic line L1 is set on the lower load side than the characteristic line L1. The characteristic line L3 may coincide with the characteristic line L2 shown in FIG. 10, or may be located on the lower load side or the higher load side than the characteristic line L2.

  The engine control unit 100 maintains the throttle opening TVO in a fully open state in the operation region on the lower load side than the characteristic line L3, and exclusively controls the valve closing timing of the intake valve 21, whereby the cylinder air filling amount is controlled. Is controlled to the target air filling amount CE. Thereby, it is possible to sufficiently secure a necessary air filling amount while suppressing generation of pump loss.

On the other hand, the engine control unit 100 controls the throttle opening TVO to be reduced between the characteristic line L1 and the characteristic line L3 as the required load increases or as the engine speed N _ENG decreases. Therefore, as the operation region of the engine 1 approaches the low speed and high load operation region in which the operation mode M needs to be set to the slow closing mode M _LIVC from the medium / high speed / low / medium load operation region, the intake port downstream of the throttle valve 57 The pressure in the intake pipe including 18 decreases. As a result, in the transient and unstable engine operation region where the operation mode M is switched, the cylinder air charge amount is prevented from temporarily becoming excessive with the change of the intake valve closing timing, and thereby pre-ignition and the like Abnormal combustion can be avoided.

FIG. 13 is a timing chart showing an example of control of the intake valve closing timing, the throttle opening TVO, and the EGR valve in the retard transition mode M _TR-R .

As shown in FIG. 13, when the engine control unit 100 executes the control in the retarded angle transition mode M _TR-R , the count value C _TR is decremented from the start timing t ₀ (the process of step S59 is performed). is performed), when the count value C _TR count end timing t ₂ becomes 0, decrement is completed. The engine control unit 100 starts the intake valve drive mechanism 30 in order to change the valve closing timing of the intake valve 21 from the first valve closing timing range IVC _1st to the second valve closing timing range IVC _2nd from the timing t ₀ when the counting is started. Thus, the closing timing of the intake valve 21 is retarded. At that time, the engine control unit 100 reduces the throttle opening TVO in proportion to the delay of the closing timing of the intake valve 21, thereby reducing the intake pipe pressure. In this way, even if the closing timing of the intake valve 21 enters the intermediate closing timing range IVC _{IM in} which abnormal combustion such as pre-ignition is concerned in the cylinder 11, the intake pipe pressure is decreased. Abnormal combustion can be prevented. Similarly, the engine control unit 100 increases the opening degree (EGR amount) Q _EGR of the EGR valve 63 in proportion to the delay of the closing timing of the intake valve 21. As a result, the external EGR having a temperature lower than that of the internal EGR that is the in-cylinder residual gas is introduced into the cylinder, so that abnormal combustion can be avoided more reliably.

The engine control unit 100 sets a necessary control parameter so that the switching of the closing timing of the intake valve 21 ends at a timing t ₁ that is earlier than the count end timing t ₂ . Then, the engine control unit 100 at the time of the lapse of t _1, QEGR set in step S12, TVO, is switched similarly to the later closing mode M _LIVC, switching of the operation mode M is completed.

FIG. 14 shows a control example of the intake valve closing _timing in the slow closing mode M _LIVC , and FIG. 15 shows a control example of the throttle opening TVO in the slow closing mode. In each figure, (A) shows the case where the throttle opening is controlled according to the target air filling amount CE, and (B) shows the case where the throttle opening is kept constant regardless of the target air filling amount CE.

In the slow closing mode _MLIVC , the engine control unit 100 sets the closing timing of the intake valve 21 within the second closing timing range IVC _2nd . As shown in FIGS. 14A and 15A, when the throttle opening is controlled in accordance with the target air filling amount CE, the intake valve 21 is controlled regardless of the increase or decrease in the target air filling amount CE. While maintaining the valve closing time constant, by controlling the throttle opening, the pressure in the intake passage including the intake port 18 downstream of the throttle valve 57 is controlled to change the cylinder air filling amount.

On the other hand, as shown in FIGS. 14B and 15B, when the throttle opening is kept constant regardless of the target air filling amount CE, the engine control unit 100 determines that the target air filling amount CE is As it increases, the intake valve closing timing is advanced within the second valve closing timing range IVC _2nd . By doing so, since the closing timing of the intake valve 21 approaches the maximum filling valve closing timing, the cylinder air filling amount increases, and the cylinder air filling amount corresponding to the increase in the target air filling amount CE. Can be increased. Here, the engine control unit 100 keeps the throttle opening TVO constant at a relatively large value. As a result, it is possible to maintain a low pressure in the intake passage and reduce pump loss.

In either case of FIGS. 14A and 14B, the engine control unit 100 _retards the closing timing of the intake valve 21 as the engine rotational speed N _ENG increases. Further, the throttle opening TVO is increased as the engine speed N _ENG increases. This is a control for responding to the fact that the intake inertia force increases as the engine speed N _ENG increases, and the maximum filling valve closing timing at the engine speed (engine speed) N _ENG is retarded. By this control, the air filling amount can be sufficiently ensured without being insufficient with respect to the target air filling amount CE.

FIG. 16 is a timing chart showing a control example of the intake valve closing timing, the throttle opening TVO, and the EGR valve in the advance angle transition mode M _TR-A .

As shown in FIG. 16, when the engine control unit 100 executes the control in the advance angle transition mode M _TR-A , the count value C _TR is decremented from the start timing t ₀ (the process of step S59 is performed). is performed), when the count value C _TR count end timing t ₂ becomes 0, decrement is completed. The engine control unit 100 controls the intake valve drive mechanism 30 to change the valve closing timing of the intake valve 21 from the second valve closing timing range IVC _2nd to the first valve closing timing range IVC _1st from the timing t ₀ when the counting is started. As a result, the closing timing of the intake valve 21 is advanced. At that time, the engine control unit 100 reduces the throttle opening TVO in proportion to the advancement of the closing timing of the intake valve 21, thereby lowering the intake pipe pressure. In this way, even if the closing timing of the intake valve 21 enters the intermediate closing timing range IVC _{IM in} which abnormal combustion such as pre-ignition is concerned in the cylinder 11, the intake pipe pressure is decreased. Abnormal combustion can be prevented. Further, the engine control unit 100 increases the opening degree (EGR amount) Q _EGR of the EGR valve 63 in proportion to the advancement of the closing timing of the intake valve 21. As a result, the external EGR having a temperature lower than that of the internal EGR that is the in-cylinder residual gas is introduced into the cylinder, so that abnormal combustion can be avoided more reliably.

  FIG. 17 shows a control example when the engine control unit 100 executes the control processing shown in the flowcharts of FIGS. This example shows a control example when mode switching is not prohibited (when all of the determinations of steps S53 to S55 are NO).

As shown in FIG. 17A, when the throttle opening is controlled in parallel in the intake valve closing control in the slow closing mode _MLIVC , the closing timing of the intake valve 21 is fixed to the most advanced side. Since the target air filling amount CE can be controlled, the displacement amount (the rotation angle of the control shaft 120 in FIG. 3) when the operation mode M is switched from the early closing mode M _EIVC to the slow closing mode M _LIVC is also minimized. Thus, the time required for switching from the early closing mode _MEIVC can be shortened as much as possible.

On the other hand, as shown in FIG. 17B, in the control of the intake valve closing _timing in the slow closing mode M _LIVC , when the throttle opening is kept constant, the operation mode M is _changed from the early closing mode M _EIVC to the slow closing mode. The displacement amount (the rotation angle of the control shaft 120 in FIG. 3) when switching to M _LIVC is maximized, but since the intake pipe pressure can be kept high, the pump loss is minimized and the fuel efficiency of the engine 1 is reduced. Can be improved.

Here, in the above-described embodiment, even when the engine control unit 100 has requested to shift from the slow closing mode M _LIVC to the early closing mode M _EIVC (that is, the operating region of the engine 1 is a region on the high load low speed side). (A region above the characteristic line L1 in FIG. 10) is shifted to a region on the low load high speed side (even if the region is below the characteristic line L2 in FIG. 10), and then a predetermined time (for example, 0 When it is determined that there is a possibility that there is a request for re-transition from the early closing mode M _EIVC to the late closing mode M _LIVC within a predetermined level within 20 seconds (that is, one of the determinations in steps S53 to S55 is YES) ), The transition from the slow closing mode M _LIVC to the early closing mode M _EIVC is prohibited. Thereby, the opening / closing drive of the throttle valve 57 accompanying the switching between the slow closing mode M _LIVC and the early closing mode M _EIVC is also prohibited. Therefore, the repeated opening / closing operation of the throttle valve 57 can be suppressed. Therefore, it is possible to prevent the prediction accuracy of the opening degree from being lowered due to the repetitive opening / closing operation of the throttle valve 57, and to sufficiently secure the prediction accuracy of the cylinder air filling amount.

Specifically, in the above embodiment, when there is a request for transition from the slow closing mode M _LIVC to the early closing mode M _EIVC , the engine control unit 100 sets the wheel slip amount V _SLIP to the predetermined slip amount V determines whether a higher _{the set,} when it is determined that the predetermined slip amount V _set or to execute the TRC control (the case of NO is determined in step S103). Then, the engine control unit 100 determines whether or not the TRC control is being executed. When it is determined that the TRC control is being executed (when the determination in step S53 is YES), the engine control unit 100 executes the process of step S64. It is like that.

That is, in the vehicle having the TRC control function, when the wheel slip amount V _SLIP is equal to or larger than the predetermined slip amount V _set (when the determination in step S103 is NO), the engine control unit 100 executes the TRC control. Thus, the engine torque (load) is once reduced, and then the engine torque increases as the gripping force of the wheels recovers. In the above-described embodiment, paying attention to this, even when there is a request for transition from the slow closing mode M _LIVC to the early closing mode M _EIVC , when the TRC control is being executed, the engine torque subsequently increases and quickly Since there is a high possibility that a re-transition request from the closing mode M _EIVC to the slow closing mode M _LIVC is made, mode switching from the slow closing mode M _LIVC to the early closing mode M _EIVC is prohibited. Thereby, the repetitive opening / closing operation | movement of the throttle valve 57 can be suppressed reliably.

Further, in the above embodiment, when there is a request for transition from the slow closing mode M _LIVC to the early closing mode M _EIVC , the engine control unit 100 _calculates the absolute value D of the time change rate (differential value) of the accelerator pedal. When the integrated value within the past predetermined time from the present is calculated and the calculated time integrated value I is equal to or greater than the predetermined threshold value _Iset (when the determination in step S54 is YES, that is, the determination in step S204 is NO) In some cases, the process of step S64 is executed .

That is, the time integral value I is a value related to the accelerator pedal operation frequency, and it can be said that the greater the value, the higher the accelerator pedal operation frequency. For example, the example shown in FIG. 18B shows a case where the operation frequency of the accelerator pedal is higher than that in the example shown in (A). In this example of (B), within the past predetermined time at time t _L. The time integration value I (within 4 seconds in this embodiment) exceeds the predetermined threshold value _Iset , whereas in the example of (A), the time integration value I is below the predetermined threshold value _Iset. Recognize. In the above embodiment, paying attention to this, when the engine control unit 100 determines that the time integral value I is equal to or greater than the predetermined threshold value _Iset , the accelerator pedal is then depressed to increase the engine load (early closing). Since there is a high possibility that a re-transition request from the mode M _EIVC to the slow closing mode M _LIVC is made), the transition from the slow closing mode M _LIVC to the early closing mode M _EIVC is prohibited. Thereby, the repetitive opening / closing operation | movement of the throttle valve 57 can be suppressed reliably.

Further, in the above embodiment, when there is a request for transition from the slow closing mode M _LIVC to the early closing mode M _EIVC , the engine control unit 100 determines _{whether the} automatic transmission mode is the manual mode or the auto mode. When the mode is set and it is determined that the manual mode is set (when the determination in step S55 is YES), the process of step S64 is executed . .

In other words, when the manual mode is selected as the shift mode of the automatic transmission, the occupant often aims for a sporty running in which the gear position is frequently switched by a shift operation. Therefore, in the above embodiment, when the engine control unit 100 determines that the transmission mode of the transmission is set to the manual mode, the engine torque is likely to increase due to the occupant's shift operation thereafter. Therefore, the transition from the slow closing mode M _LIVC to the early closing mode M _EIVC is prohibited. Thereby, the repeated opening / closing operation | movement of the throttle valve 57 can be suppressed much more reliably.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiment, but includes various other configurations. That is, in the above embodiment, the operation mode M of the engine 1 is controlled to be hysteresis in the region between the characteristic line L1 and the characteristic line L2 shown in FIG. 10, but such hysteresis control is necessarily performed. There is no.

  Moreover, in the said embodiment, although the said vehicle is made into the vehicle provided with the TRC control function, it does not necessarily need to be provided with the TRC control function.

  Moreover, in the said embodiment, although the automatic transmission mounted in the said vehicle is made into the automatic transmission provided with the manual mode, the normal automatic transmission which does not have a manual mode may be sufficient.

The present invention is useful for a control method and an internal combustion engine system of an internal combustion engine system, particularly useful when applied to a vehicle having a traction control function.

IVC _1st early closing range (first valve closing timing range)
IVC _2nd slow closing range (second valve closing timing range)
V _SLIP wheel slip amount V _set predetermined slip amount I time integral value I _set predetermined threshold (predetermined value)
D Absolute value of rate of change of time CE Target air filling amount α Accelerator opening signal 1 Engine (internal combustion engine)
11 cylinder 15 piston
17 Combustion chamber 21 Intake valve 30 Intake valve drive mechanism (intake valve closing timing variable mechanism)
32 Variable valve timing mechanism (Intake valve closing timing variable mechanism)
55b Intake path 57 Throttle valve 100 Engine control unit

Claims (6)

A cylinder that defines a combustion chamber with a reciprocating piston, an intake passage through which air introduced into the combustion chamber passes, an intake valve that is driven by a crankshaft and that can shut off the intake passage from the combustion chamber; A control method for an internal combustion engine, comprising: a throttle valve provided in an intake passage so as to be openable and closable; and an intake valve closing timing variable mechanism for controlling a valve closing timing of the intake valve driven by the crankshaft,
When the engine operating state consisting of the engine load and the engine speed in the internal combustion engine is in the first operating region on the high load low speed side, in each cylinder cycle, the maximum filling valve that maximizes the air filling amount at the engine speed A late closing step of controlling the intake valve closing timing variable mechanism so as to close the intake valve within a delay closing range set on the retard side of the timing;
When the engine operating state is in the second operating region at a lower load or higher speed than the first operating region, in each cylinder cycle, it is set to an advance side with respect to the maximum filling valve closing timing and the delayed closing is performed. An early closing step of controlling the intake valve closing timing variable mechanism so as to close the intake valve within an early closing range separated from the range;
When there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, the first operation from the engine operation state in the second operation region is performed within a predetermined period. A re-transfer determination step for determining whether or not the possibility that there is a re-transfer request to the engine operation state of the region is a predetermined level or more;
When it is determined that the possibility is less than the predetermined level, the intake valve closing timing variable mechanism is controlled so that the closing timing of the intake valve shifts from the late closing range to the early closing range; A transition control step of temporarily driving the throttle valve in the closing direction;
A transition prohibiting step of controlling the intake valve closing timing variable mechanism so that the closing timing of the intake valve stays in the delayed closing range when it is determined that the possibility is equal to or higher than the predetermined level. A control method for an internal combustion engine system. The method for controlling an internal combustion engine according to claim 1,
The internal combustion engine is mounted on a vehicle,
The re-transfer determination step includes a wheel slip amount detection step of detecting a slip amount of the wheel of the vehicle,
The re-transfer determination step includes the slip detected in the wheel slip amount detection step when there is a transfer request from the engine operation state in the first operation region to the engine operation state in the second operation region. When the amount is less than the predetermined amount, it is determined that the possibility is less than the predetermined level. On the other hand, when the slip amount detected in the wheel slip amount detection step is greater than or equal to the predetermined amount, the possibility is A control method for an internal combustion engine system, characterized in that it is a step of determining that the property is not less than the predetermined level. In the control method of the internal combustion engine according to claim 1 or 2,
The vehicle is provided with an accelerator pedal operated by an occupant,
The control method for an internal combustion engine system, wherein the re-transition determination step is a step of acquiring information related to an accelerator pedal depression amount and determining the possibility based on the acquired information. The control method of the internal combustion engine system according to claim 3,
The remigration determination step is
A time change rate calculating step of detecting the depression amount of the accelerator pedal and calculating the time change rate;
A time integration value calculation step of calculating a time integration value obtained by integrating the absolute value of the time change rate calculated by the time change rate calculation step from the present to the past predetermined period,
When there is a request for transition from the engine operating state in the first operating region to the engine operating state in the second operating region, the time integrated value calculated in the time integrated value calculating step is less than a predetermined value. In some cases, it is determined that the possibility is less than a predetermined level, and when the time integration value is not less than the predetermined value, the possibility is not less than the predetermined level. A method for controlling an internal combustion engine system. In the control method of the internal-combustion engine system according to any one of claims 1 to 4,
The internal combustion engine is mounted on a vehicle,
The vehicle has an automatic mode that can be set by switching between an auto mode that automatically switches the shift speed based on a preset shift characteristic and a manual mode that switches the shift speed based on a manual operation. A transmission is provided,
As a setting mode of the transmission, further comprising a mode determination step of determining which mode is set between the auto mode and the manual mode,
In the re-transition determination step, when there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, in the mode determination step, the automatic transmission When it is determined that the mode is set to the auto mode, it is determined that the possibility is less than the predetermined level, and when it is determined that the setting mode of the automatic transmission is set to the manual mode. A method for controlling an internal combustion engine system, wherein the method is a step of determining that the possibility is equal to or higher than the predetermined level. A cylinder that defines a combustion chamber together with a reciprocating piston, an intake passage through which air introduced into the combustion chamber passes, an intake valve that is driven by a crankshaft and that can shut off the intake passage from the combustion chamber, and the intake air A control apparatus for an internal combustion engine, comprising: an intake valve closing timing variable mechanism capable of changing a valve closing timing; a throttle valve provided in the intake passage so as to be openable and closable; and a throttle actuator for driving the throttle valve. There,
When the engine operating state consisting of the engine load and the engine speed in the internal combustion engine is in the first operating region on the high load low speed side, in each cylinder cycle, the maximum filling valve that maximizes the air filling amount at the engine speed Delay closing setting means for controlling the intake valve closing timing variable mechanism so as to close the intake valve within a delay closing range set on the retard side of the timing;
When the engine operating state is in the second operating region at a lower load or higher speed than the first operating region, in each cylinder cycle, it is set to an advance side with respect to the maximum filling valve closing timing and the delayed closing is performed. An early closing setting means for controlling the intake valve closing timing variable mechanism so as to close the intake valve within an early closing range separated from the range;
When there is a request for transition from the engine operation state in the first operation region to the engine operation state in the second operation region, the first operation from the engine operation state in the second operation region is performed within a predetermined period. Re-transfer determination means for determining whether or not the possibility that there is a re-transfer request to the engine operation state of the region is a predetermined level or more;
When it is determined that the possibility is less than the predetermined level, the intake valve closing timing variable mechanism is controlled so that the closing timing of the intake valve shifts from the late closing range to the early closing range; Transition control means for controlling the throttle actuator so that the throttle valve temporarily operates in the closing direction;
A transition prohibiting means for controlling the intake valve closing timing variable mechanism so that the closing timing of the intake valve stays in the delayed closing range when it is determined that the possibility is equal to or higher than the predetermined level;
A control device for an internal combustion engine, comprising:

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