JP4998323B2 - Internal combustion engine system and control method for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine system having an intake valve that blocks inflow of air into a cylinder.

  2. Description of the Related Art Conventionally, for the purpose of preventing the occurrence of abnormal combustion at the time of starting, a system has been developed that controls the opening timing or closing timing of an intake valve of an internal combustion engine in accordance with operating conditions.

For example, Patent Document 1 discloses a system that changes the closing timing of an intake valve in accordance with the engine temperature when the internal combustion engine is started. In this system, as the engine temperature increases, the closing timing of the intake valve is controlled to the retard side, thereby reducing the effective compression ratio of the engine, thereby preventing abnormal combustion such as self-ignition at start-up. . Here, Patent Document 1 includes a first embodiment in which the closing timing of the intake valve when the internal combustion engine is stopped is held at an intermediate position by an intermediate lock mechanism attached to a portion connected to the crankshaft. The second embodiment is disclosed in which the valve closing timing is set to the most retarded time and the time when the amount of air introduced into the cylinder becomes small.
JP 2007-113440 A

  In the first embodiment of the conventional method, since the intermediate lock mechanism is resistant to engine rotation, the startability may be deteriorated. On the other hand, in the second embodiment, since the closing timing of the intake valve is set to the most retarded angle, sufficient air may not be introduced into the cylinder at the start, and startability may be deteriorated.

  In view of such circumstances, an object of the present invention is to provide an internal combustion engine system capable of improving startability with a simple configuration.

As means for solving the above-mentioned problems, the present invention provides a cylinder that accommodates a reciprocating piston and forms a combustion chamber, a crankshaft connected to the piston, and a cam that rotates in synchronization with the crankshaft. A shaft, an intake passage through which air introduced into the cylinder passes, and an intake valve that reciprocates in accordance with rotation of the camshaft and blocks inflow of air from the intake passage into the cylinder. An internal combustion engine, a cam phase variable mechanism that changes a rotation phase of the cam shaft with respect to the crankshaft by supplying power, and changes a closing timing of the intake valve, and is supplied to the cam phase variable mechanism and control means for controlling the power, the control means increases the power supplied to the cam phase variable mechanism immediately after the start of the internal combustion engine, the cam The phase variable mechanism is configured to change a rotational phase of the camshaft with respect to the crankshaft in a state where the power is cut off, and to determine whether the intake valve is closed when the internal combustion engine is started. The phase corresponds to the time when the amount of introduction is maximum, and the closing timing of the intake valve is changed in a direction in which the amount of air introduced into the cylinder decreases as the power supplied increases. An internal combustion engine system is provided (claim 1).

In the present invention, the term “starting” refers to the period during which the starting means such as a starter motor is being driven, and “immediately after starting” is immediately after the start of the driving of the starting means and the rotational speed has increased to some extent. Refers to the state of being.

According to the internal combustion engine system of the present invention , in the stop state of the internal combustion engine in which the power to the camshaft phase variable mechanism is shut off, the closing timing of the intake valve is the maximum amount of air introduced into the cylinder. When the internal combustion engine is started after the stop, a sufficient amount of air introduced into the cylinder can be ensured. As a result, the internal combustion engine can be rotated while the power to the camshaft phase varying mechanism is cut off. That is, when the internal combustion engine has a large rotational resistance, the power for rotating the internal combustion engine by the starting means such as the starter motor, that is, the power for cranking, while sufficiently securing the cylinder air amount and improving the output torque. Can be secured sufficiently, and the startability of the internal combustion engine at a particularly low temperature is improved.

Further, since the amount of air introduced into the cylinder is reduced immediately after the internal combustion engine is started, the air amount in the cylinder is excessively increased immediately after the start, and the temperature in the cylinder is suppressed from becoming too high. . That is, with this configuration, it is possible to suppress the occurrence of self-ignition accompanying the temperature rise in the cylinder immediately after starting while securing a sufficient amount of air at the time of starting.

  The power supplied to the cam phase variable mechanism includes, for example, electric power (Claim 2).

  In the present invention, the closing timing of the intake valve in a state where the power to the cam phase variable mechanism is cut off is the most advanced in the variable range of the closing timing of the intake valve changed by the cam phase variable mechanism. An angular time is preferred (Claim 3).

  In this way, the intake valve can be easily set to the time when the amount of introduced air is maximized without providing an intermediate holding mechanism for holding the intake valve at an intermediate position as in the conventional system. can do. This reduces the rotational resistance of the internal combustion engine and further improves the startability.

The control means, preferably configured to cut off the power supply to the cam phase variable mechanism at the start of the internal combustion engine (claim 4).

  In this way, it is possible to avoid a situation in which the power supplied to the starting means such as the starter motor is reduced due to the power being supplied to the control means at the time of starting, and the startability can be improved. .

Here, in an internal combustion engine having a high compression ratio such that the geometric compression ratio of the cylinders of the internal combustion engine is 13 or more, a large amount of work is required for compression, and further improvement in startability is required. Therefore, it is effective to apply the control system of the internal combustion engine to such an internal combustion engine with a high compression ratio ( claim 5 ).

The present invention also includes a cylinder that houses a reciprocating piston and that forms a combustion chamber, an intake passage through which air introduced into the cylinder passes, and an inflow of air from the intake passage into the cylinder. A control method for an internal combustion engine having an intake valve that shuts off, wherein the intake valve is closed when the internal combustion engine is stopped, and the amount of air introduced into the cylinder when the internal combustion engine is started a step but to control braking a time when the maximum, at the start of the internal combustion engine, when the temperature of the internal combustion engine is higher than a preset reference temperature, as compared with the case lower than the reference temperature, of the intake valve After the valve closing timing is controlled to a timing when the amount of air introduced into the cylinder becomes small, and after the internal combustion engine is rotated a predetermined number of times in a state where combustion in the combustion chamber is not performed The combustion A step for starting the combustion in the internal, immediately after the start of the internal combustion engine, the step of the closing timing of the intake valve, to control braking in time to the introduction of air into the cylinder is smaller than at start to provide a control method for an internal combustion engine which comprises bets (claim 6).

According to this method, when the internal combustion engine is stopped, the closing timing of the intake valve is set so that the amount of air introduced into the cylinder is maximized, so that a sufficient amount of air can be secured at the time of starting. At the same time, since the amount of air introduced into the cylinder is reduced immediately after the internal combustion engine is started, it is possible to suppress the occurrence of self-ignition due to an excessive increase in the temperature in the cylinder immediately after the start.

In addition, when the engine is started in a state where the temperature of the internal combustion engine is higher than the reference temperature and the temperature in the cylinder tends to be high, the amount of air introduced into the cylinder can be kept small. The occurrence of self-ignition can be suppressed.

Further, when the temperature of the internal combustion engine is higher than the reference temperature at the time of starting the internal combustion engine, the internal combustion engine is rotated a predetermined number of times and then combustion in the combustion chamber is started. In a state where the temperature of the internal combustion engine where ignition is likely to occur is high, the closing timing of the intake valve is not changed with sufficient responsiveness, and the amount of air introduced into the cylinder immediately after starting is not sufficiently suppressed. However, the occurrence of abnormal combustion such as self-ignition is more reliably suppressed. That is, according to this method, abnormal combustion can be more reliably suppressed without increasing the speed of changing the closing timing of the intake valve.

Further, in the above method, as a specific method of changing the closing timing of the intake valve, for example, when power is supplied, the intake valve is reciprocated in synchronization with a crankshaft connected to the piston. There is a method of using a cam phase variable mechanism for changing the valve closing timing of the intake valve by changing the rotation phase of the camshaft to be moved with respect to the crankshaft. Then, in the embodiment using the variable cam phase mechanism, Oite during startup of the internal combustion engine, wherein when the temperature of the internal combustion engine is lower than or equal to the reference temperature which is set in advance, cut off the power to the cam phase varying mechanism ( Claim 7 ).

  In this way, it is possible to avoid a situation in which the power supplied to the starting means such as a starter motor is reduced, and startability can be improved.

Further, in the method, the flow passage area changing means capable of changing the flow passage area of the intake passage is used, and immediately after the internal combustion engine is started, the flow passage area of the intake passage is enlarged by the flow passage area changing means. ( Claim 8 ).

  In this way, the pressure in the intake passage is increased and the pump loss is reduced, so that the engine rotation after starting is stabilized and the engine efficiency is improved.

  As described above, according to the present invention, an internal combustion engine system capable of improving startability with a simple configuration can be provided.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows the overall structure of an engine system to which the present invention is applied. This engine system includes an engine body (internal combustion engine) 1 and an engine controller (control means) 100 for controlling various actuators attached to the engine body 1.

  The engine body 1 is a four-cycle spark ignition type internal combustion engine mounted on a vehicle such as an automobile, and its output shaft is coupled to drive wheels via a transmission to propel the vehicle. The engine body 1 includes a cylinder block 12 and a cylinder head 13 placed thereon. A plurality of cylinders 11 are formed inside the cylinder block 12 and the cylinder head 13. Although the number of these cylinders 11 is not specifically limited, For example, four cylinders 11 are formed. A crankshaft 14 is rotatably supported on the cylinder block 11 by a journal, a bearing or the like.

  Pistons 15 are slidably fitted in the cylinders 11, and combustion chambers 17 are defined above the pistons 15, respectively.

  Here, in this embodiment, the engine body is the ratio of the volume of the combustion chamber 17 when the piston 15 is located at the top dead center and the volume of the combustion chamber 17 when the piston 15 is located at the bottom dead center. The geometric compression ratio of 1 is set to approximately 14. Of course, the value of this geometric compression ratio is not limited to 14. For example, the geometric compression ratio is preferably higher from the viewpoint of improving the engine efficiency. However, if the geometric compression ratio is increased, the temperature in the cylinder becomes too high in the compression stroke, and the possibility of self-ignition occurring at an unexpected timing increases. Therefore, the geometric compression ratio of the engine body 1 is preferably 13 or more and 16 or less.

  The cylinder head 13 is formed with two intake ports 18 and two exhaust ports 19 communicating with each combustion chamber 17. The cylinder head 13 includes an intake valve (intake valve) 21 for shutting off each intake port 18 from the combustion chamber 17 and an exhaust valve for shutting off each exhaust port 19 from the combustion chamber 17. (Exhaust valve) 22 is provided. The intake valve 21 is driven by an intake valve drive mechanism 30 described later, thereby opening and closing each intake port 18 at a predetermined timing. On the other hand, the exhaust valve 22 is driven by an exhaust valve driving mechanism 40 described later, thereby opening and closing each exhaust port 19.

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

  The intake valve drive mechanism 30 is provided with an intake camshaft phase variable mechanism (cam phase variable mechanism) 32 between the power transmission mechanism and the intake camshaft 31. The intake camshaft phase varying mechanism 32 is for changing the valve timing of the intake valve 21, and is arranged coaxially with the intake camshaft 31 and directly driven by the crankshaft 14 and the intake cam. The phase difference between the crankshaft 14 and the intake camshaft 31 is changed by changing the phase difference between the shaft 31 and the shaft 31. As a result, the opening timing (opening timing) and closing timing (closing timing) IVC of the intake valve 21 are changed while the valve opening period and the lift amount, that is, the valve profile, of the intake valve 21 are kept constant. Although the specific configuration of the intake camshaft phase varying mechanism 32 is not particularly limited, it is preferable to use, for example, an electromagnetic type as shown in FIGS.

  FIG. 2 is a schematic sectional view of the camshaft phase varying mechanism 32. The intake camshaft phase varying mechanism 32 is an electromagnetic type, and includes a planetary gear device 33 shown in FIG. 3, an electromagnetic actuator 34 shown in FIG. The planetary gear unit 33 transmits rotation between the intake camshaft 31 and the sprocket 31a, and includes a ring gear 33a, three planetary pinion gears 33b, a sun gear 33c, and a planetary carrier 33d.

  The ring gear 33a is connected to an outer casing 35 (to be described later) of the electromagnetic actuator 34, and rotates coaxially and integrally with the outer casing 35. The sun gear 33c is attached to the tip of the intake camshaft 31 and rotates coaxially and integrally with the intake camshaft 31. Further, the planetary carrier 33d is formed in a substantially triangular shape, and a shaft 33e is projected from each of the three corners. The planetary carrier 33d is connected to the sprocket 31a via these shafts 33e, and rotates coaxially and integrally with the sprocket 31a. Each planetary pinion gear 33b is rotatably supported by each shaft 33e of the planetary carrier 33d, and is disposed between the sun gear 33c and the ring gear 33a, and always meshes therewith.

  The electromagnetic actuator 34 includes an outer casing 35, a core 36, an electromagnet 37, and a return spring 38. The outer casing 35 is hollow, and the core 36 is relatively rotatably provided therein. The core 36 includes a base 36a having a circular cross section and two arms 36b and 36b extending radially therefrom. The base 36a of the core 36 is attached to the planetary carrier 33d, and rotates coaxially and integrally with the planetary carrier 33d. Further, on the inner peripheral surface of the outer casing 35, a pair of stoppers 35a and 35b at the most advanced angle position and the most retarded angle position are set as one set, and a total of two sets of stoppers 35a and 35b are provided with a space therebetween. It has been.

  Each arm 36b of the core 36 is disposed between the pair of stoppers 35a and 35b, and the core 36 has the most advanced angle position (the arm 34b abuts on the most advanced angle position stopper 35a and is locked). 4 between the position indicated by the solid line in FIG. 4 and the most retarded angle position (position indicated by the two-dot chain line in FIG. 4) that contacts and is locked with the most retarded angle position stopper 35b. And is relatively rotatable.

  In a compressed state, the return spring 38 is stretched between one of the most retarded angle position stoppers 35b and an arm 36b facing the stopper. 36b is urged toward the most advanced angle position stopper 35a.

  The electromagnet 37 is attached to the most retarded angle position stopper 35b on the opposite side to the return spring 38, and is provided on the end of the most retarded angle position stopper 35b on the side facing the arm 36b in a flush state. It has been. The electromagnet 37 is connected to an automobile power supply system including an alternator, a battery, and the like, and is excited based on the valve timing of the intake valve 21 calculated by the engine controller 100 described later, and the opposing force is generated by the electromagnetic force. The arm 36b is sucked against the urging force of the return spring 38 and rotated toward the most retarded position stopper 35b.

In the intake camshaft phase varying mechanism 32 configured as described above, when no electric power is supplied from the battery or the like to the intake camshaft phase varying mechanism 32 and the electromagnet 37 of the electromagnetic actuator 34 is not excited, The core 36 is held at the most advanced position where the arm 36b abuts on the most advanced position stopper 35a by the urging force of the return spring 38. That is, when power is not supplied to the intake camshaft phase varying mechanism 32, the valve timing of the intake valve 21 is held at the most advanced timing. Then, when electric power is supplied to the intake camshaft phase varying mechanism 32 and the electromagnet 37 is excited, the core 36 rotates against the urging force of the return spring 38, whereby the intake valve 21. The valve timing is controlled to the retard side. In this embodiment, the opening period of the intake valve 21 is kept constant, and the opening timing (opening timing) and closing timing (closing timing) IVC of the intake valve 21 are changed integrally. The phase angle of the intake camshaft 31 is detected by a cam phase sensor 39, and the signal θ _{VCT_A} is transmitted to the engine control means 100.

Further, in the present embodiment, the closing timing IVC of the intake valve 21 at the most advanced timing is such that the amount of air introduced into the cylinder 11 at the time of starting (the air filling amount CE) is maximum as shown in FIG. Is set so as to coincide with the starting-time air amount maximum timing θ _max and when the intake camshaft phase variable mechanism 32 is not supplied with electric power, the closing timing IVC of the intake valve 21 is the starting-time air amount. The maximum timing θ _max is _reached . Therefore, in the present engine body 1, when the engine body 1 is started and power supply to the intake camshaft phase variable mechanism 32 is started, the air filling amount CE can be maximized, and startability is improved. Secured.

Referring again to FIG. 1, the intake port 18 communicates with the surge tank 55 a through the intake manifold 55. A throttle body 56 is provided in the intake passage upstream of the surge tank 55a. Inside the throttle body 56, a throttle valve 57 (flow passage area changing means) for adjusting the intake flow rate from the outside toward the surge tank 55a is pivotally provided. The throttle valve 57 can change the intake flow rate by changing the opening area of the intake passage, that is, the flow passage area, and can change the pressure in the intake passage downstream of the throttle valve 57. The throttle valve 57 is driven by a throttle actuator 58. The throttle actuator 58, the opening degree TVO of the throttle valve 57 is such that the target throttle opening TVO _D calculated by the engine controller 100 described later for driving the throttle valve 57. Here, the intake passage in the claims includes all of the intake port 18, the intake manifold 55, and the surge tank 55a downstream of the throttle valve 57. In the present embodiment, the air filling amount CE filled in the cylinder 11 is controlled to an appropriate value by adjusting the opening degree of the throttle valve 57 and the closing timing IVC of the intake valve 21.

  The exhaust port 19 communicates with an exhaust pipe via an exhaust manifold 60. An exhaust gas purification system is disposed in the exhaust pipe. The specific configuration of the exhaust gas purification system is not particularly limited, and examples thereof include those having a catalytic converter 61 such as a three-way catalyst, a lean NOx catalyst, and an oxidation catalyst.

The intake manifold 55 and the exhaust manifold 60 are communicated with each other by an EGR pipe 62, and a part of the exhaust gas is circulated to the intake side. The EGR pipe 62 is provided with an EGR valve 63 for adjusting the flow rate of EGR gas that circulates through the EGR pipe 62 to the intake side. The EGR valve 63 is driven by an EGR valve actuator 64. The EGR valve actuator 64 drives the EGR valve 63 so that the opening degree of the EGR valve 63 becomes an EGR opening degree EGR _open calculated by the engine controller 100 described later, thereby reducing the flow rate of the EGR gas. Adjust to an appropriate value.

  A spark plug 51 is attached to the cylinder head 13 so that the tip of the cylinder head 13 faces the combustion chamber 17. The ignition plug 51 generates a spark in the combustion chamber 17 when energized by the ignition system 52 based on an ignition timing signal SA calculated by an engine controller 100 described later.

  In addition, a fuel injection valve 53 for directly injecting fuel into the combustion chamber 17 is attached to the cylinder head 13 so that the tip thereof faces the combustion chamber 17. More specifically, the tip of the fuel injection valve 53 is positioned below the two intake ports 18 in the vertical direction, and is positioned between the two intake ports 18 in the horizontal direction. Has been placed. The fuel injection valve 53 is energized only for a predetermined period based on a signal of a fuel injection amount FP calculated by an engine controller 100 described later by the fuel system 54 by a solenoid provided in the fuel injection valve 53. A predetermined amount of fuel is injected into the chamber 17.

  The engine controller 100 is a controller based on a well-known microcomputer, and performs input / output of various signals, a CPU for executing a program, a memory including a RAM and a ROM for storing the program and data, and the like. And an I / O bus.

The engine controller 100 detects the engine cooling water temperature T _ENG detected by the water temperature sensor 77, the intake air amount AF detected by the air flow meter 71, and the intake pressure sensor 72 via the I / O bus. The air pressure MAP in the intake manifold 55, the crank angle pulse signal detected by the crank angle sensor 73, the oxygen concentration EGO of the exhaust gas detected by the oxygen concentration sensor 74, and the vehicle driver detected by the accelerator opening sensor 75 Various signals such as the accelerator pedal depression amount α and the vehicle speed VSP detected by the vehicle speed sensor 76 are read. Further, the engine controller 100 reads a start signal from an ignition key switch (IG key) provided in the vehicle.

Then, the engine controller 100 determines that the amount of air introduced into the cylinder 11, that is, the air filling amount CE in the cylinder 11, the ignition timing, and the like becomes an appropriate value according to the operating conditions based on each input information. Thus, command values for various actuators are calculated. For example, command values such as the throttle opening TVO, the fuel injection amount FP, the ignition timing SA, the intake valve timing θ _VCT , the EGR opening EGR _open, etc. are calculated, and these are calculated as the throttle actuator 58, fuel system 54, ignition system 52. And output to the intake camshaft phase varying mechanism 32 and the EGR valve actuator 64.

  A specific calculation procedure in the engine controller 100 will be described with reference to the flowchart of FIG.

  First, various signals from the water temperature sensor 77 and the like are read (step S1).

Next, it is determined whether or not the starter motor is being driven (step S2). If this determination is YES, that is, if the starter motor is being driven, it is further determined whether or not the start continuation flag _FSTART is 1 (step S3). The start continuation flag F _START is a flag indicating whether or not the current start state is a start state that has been continued since the previous calculation. The start continuation flag F _START = 1 indicates that the current start state is the previous calculation time. The start continuation flag F _START = 0 indicates that the _engine is not in the starting state or that the current starting state is not the starting state that has been continued since the previous calculation.

  If the determination in step S3 is YES, that is, if starting is continued, the process proceeds to step S7.

On the other hand, if the determination in step S3 is NO, that is, where the start has been started, the start continuation flag _FSTART is first set to 1 (step S4). Then, based on the temperature T _ENG of the engine coolant, a target value θ _{VCT_D} for the closing timing IVC of the intake valve 21 is set (step S5). Specifically, as shown in FIG. 7, when the temperature T _ENG of the engine cooling water is equal to or lower than T1, the target value θ _{VCT_D} is _set to the maximum air amount at start time θ _max and the temperature T of the engine cooling water T _{When ENG} is equal to or greater than T2, the target value θ _{VCT_D} is _set to the most retarded timing, and when the engine coolant temperature T _ENG is T1 to T2, the target value θ _{VCT_D} is _set to the start-up air amount maximum timing. The timing is set to be retarded in proportion to the increase in the engine coolant temperature _TENG between θ _max and the most retarded timing. The T1 is, for example, 30 ° C., and the T2 is, for example, 80 ° C.

Here, if it is controlled to closing timing IVC is starting air amount up timing theta _max of the intake valve 21, startability is improved because a sufficient amount of air is introduced into the cylinder 11. Moreover, in the engine body 1, as described above, the closing timing IVC of the intake valve 21 is maintained at the start-up air amount maximum timing θ _max in a state where power is not supplied to the intake camshaft phase varying mechanism 32. Has been. Therefore, when the closing timing IVC of the intake valve 21 is controlled to the start-up air amount maximum timing θ _max , it is not necessary to supply power to the intake camshaft phase varying mechanism 32 as shown in FIG. The startability is further enhanced by sufficiently securing the power supplied to the vehicle. Therefore, under the condition where the engine coolant T _ENG is relatively low (T _ENG ≦ T1), as described above, the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is set as the maximum air amount at starting θ _max . by controlling the closing timing IVC of the intake valve 21 to the starting amount of air up timing theta _max, to ensure startability.

On the other hand, when the temperature of the engine main body 1 is high, if the amount of air introduced into the cylinder 11 increases, the temperature in the cylinder 11 at the time of compression becomes too high, and self-ignition may occur. . Therefore, under the condition where the engine coolant T _ENG is relatively high (T _ENG > T1), as described above, the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is set to be greater than the maximum air amount at start time θ _max. By controlling the closing timing IVC of the intake valve 21 to the retarded angle side on the retarded angle side, the amount of air introduced into the cylinder 11 is reduced to suppress the occurrence of self-ignition.

Next, in step S6, based on the engine coolant temperature T _ENG , a waiting time t _START is calculated, which is a time during which fuel injection is prohibited after starting is started and generation of sparks in the combustion chamber 17 is prohibited. . Specifically, as shown in FIG. 8, when the engine coolant temperature T _ENG is equal to or lower than T1, the waiting time t _{START is set} to 0, and when the engine coolant temperature T _ENG is equal to or higher than T2. the latency _{t START} and the predetermined time Ct, when the temperature _{T ENG} of the engine cooling water is T1~T2, the target value θ the predetermined time Ct of _{VCT_D} and engine coolant temperature T between 0 _The time is proportional to the increase in _ENG .

As described above, under the condition where the engine coolant T _ENG is relatively high (T _ENG > T1), the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is retarded from the maximum air amount at start time θ _max. By controlling the closing timing IVC to the retard side, the amount of air introduced into the cylinder 11 is reduced to suppress the occurrence of self-ignition. However, depending on the type of the intake camshaft phase varying mechanism 32, the response is not sufficient, and the closing timing IVC of the intake valve 21 cannot be controlled to the retard side immediately at the start, and the amount of air in the cylinder 11 is reduced. May be excessive.

In view of this, the engine controller 100 performs fuel injection into the combustion chamber 17 for the first time after the elapse of the waiting time _tSTART from the start of start under the operating condition in which the temperature T _ENG of the engine cooling water is greater than the T1. By generating a spark in the internal combustion engine 17, combustion is not started in an excessive air amount state, that is, the occurrence of self-ignition is more reliably suppressed. In this way, even if the drive of the intake valve 21 is delayed and excessive air is introduced into the cylinder 11 at the start of startup, the fuel injection and ignition are not performed, thereby avoiding the occurrence of self-ignition. can do.

In step S6, the waiting time t _START is converted into the number of calculation cycles based on the calculation step time Δt and substituted into the waiting time counter C _START .

Next, it is determined whether or not the waiting time counter C _START is greater than 0 (step S7). When this determination is YES, that is, when it is determined that the waiting time is still in progress, the waiting time counter C _START is decremented (step S8). Then, the fuel injection amount FP is set to zero and ignition is prohibited (step S9). On the other hand, when the determination in step S7 is NO, that is, when it is determined that the operating condition has no waiting time or the waiting time has ended, the fuel injection amount FP and the ignition timing SA corresponding to the start time are set. calculate. Thereafter, the process proceeds to step S11, and sets the target throttle opening TVO _D is a target value of the throttle opening TVO to the starting target value _{TVO START,} the process proceeds to step S12. The starting throttle opening target value TVO _START is set so as to increase as the engine temperature _TENG is lower.

If the determination in step S2 is NO, that is, if the starter motor is not being driven, the start start continuation flag _FSTART is reset to 0 (step S20), and the fuel injection amount FP and ignition during normal operation are reset. Time SA, target throttle opening TVO _D , and target value θ _{VCT_D} of intake valve 21 closing timing IVC are calculated (step S21).

Target throttle opening TVO _D in the normal operation is set larger than the starting throttle opening TVO _START, the throttle opening TVO is controlled to the open side immediately after the start. In this way, when the throttle opening TVO is controlled to the open side, the pump loss is reduced, so that the start is stabilized. Moreover, the engine efficiency in normal operation can be improved.

Further, the closing timing IVC of the intake valve 21 during normal operation is set to the retard side with respect to the maximum air amount timing θ _max at the start, and the intake valve 21 is controlled to the retard side immediately after the start. . After startup, the engine speed has increased to some extent and the temperature of the engine body 1 has increased due to the start of combustion. Therefore, after starting, the closing timing IVC of the intake valve 21 is controlled to the retard side to reduce the air charge amount CE, thereby suppressing the occurrence of self-ignition.

After each target value or the like is calculated, the process proceeds to step S12, and each actuator is driven based on the calculated value. Specifically, the signal θ _{VCT_D} is output to the intake camshaft phase varying mechanism 32. The intake camshaft phase varying mechanism 32 operates so that the phase of the intake camshaft 31 with respect to the crankshaft 14 has a value corresponding to θ _{VCT_D} . Signal TVO _D is outputted to the throttle actuator 58. Then, as the opening degree TVO of the throttle valve 57 becomes a value corresponding to the TVO _D, the throttle actuator 58 is operated. The signal FP is output to the fuel system 54. An amount of fuel corresponding to FP per cylinder cycle is injected from the fuel injection valve 53. Then, the signal SA is output to the ignition system 52. At a time corresponding to SA in the cylinder cycle, the spark plug 51 ignites, and the air-fuel mixture in the combustion chamber 17 is ignited. As a result, an output torque required by the engine body 1 is generated from the crankshaft 14 by igniting and burning the required amount of air-fuel mixture consisting of air and fuel at an appropriate time.

The behavior of each actuator based on the above control procedure is shown in FIG. 9 and FIG. FIG. 9 shows a behavior at a normal time when the temperature T _ENG of the engine cooling water is equal to or lower than T1, and FIG. 10 shows a behavior at a high temperature when the temperature T _ENG of the engine cooling water is equal to or higher than T1.

As shown in FIG. 9, under normal operating conditions, while the starter motor is ON, that is, when the starter motor is driven, no power is supplied to the intake camshaft phase varying mechanism 32, and the closing timing IVC of the intake valve 21 is at its maximum. The advance timing is controlled to the start-up air amount maximum timing θ _max and the throttle opening TVO is controlled to the start target value TVO _START . On the other hand, when the starter motor is turned off, the closing timing IVC of the intake valve 21 is controlled to the retard side, and the throttle actuator 58 is controlled so that the throttle opening TVO becomes large. Further, fuel injection and ignition are started at the same time when the starter motor is turned on. In the graph of the closing timing IVC of the intake valve 21 in FIG. 9, the solid line indicates the target value, and the broken line indicates the actual timing.

On the other hand, when the temperature of the engine main body 1 is high, as shown in FIG. 10, the starter motor is turned on and power is supplied to the intake camshaft phase varying mechanism 32 at the same time to close the intake valve 21. Timing IVC is controlled to the retard side. Further, fuel injection and ignition are prohibited during a predetermined waiting time _tSTART until a counter described later becomes 0, and fuel injection and ignition are performed only after this waiting time _tSTART . Here, the throttle opening TVO is controlled to a small starting target value TVO _START in accordance with the engine temperature _TENG . Further, after the starter motor is turned off, the closing timing IVC of the intake valve 21 is controlled to the retard side and the throttle opening TVO is controlled to the open side, as in normal operating conditions.

With the control described above, in the present engine system, the closing timing of the intake valve 21 is controlled to the maximum start air amount timing _θmax , so that a sufficient amount of air is introduced into the cylinder 11 to ensure startability. Is done.

  Here, the power supplied to the intake camshaft phase varying mechanism 32 is not limited to electric power.

Further, the start-up air amount maximum timing θ _max may be an intermediate position of the operating range instead of the most advanced position. However, if the maximum start-time air amount timing θ _max is set to the most advanced position, there is no need to provide a mechanism for holding the intake valve 21 at the intermediate position, which is accompanied by a reduction in the rotational resistance of the engine. Startability can be improved.

  Further, the control method after starting is not limited to the above. However, if the valve timing of the intake valve 21 is controlled to the retard side immediately after the start and the amount of air introduced into the cylinder 11 is reduced, the self-ignition immediately after the start can be suppressed. Further, if the throttle opening TVO is controlled to the opening side immediately after the start, the pump loss can be reduced and the engine rotation can be stabilized.

The closing timing of the intake valve 21 may be kept constant regardless of the engine coolant temperature _TENG . However, if the closing timing of the intake valve 21 is controlled so that the amount of air introduced into the cylinder 11 becomes small at high temperatures, the temperature of the air in the cylinder 11 can be suppressed from becoming too high, and the occurrence of self-ignition can be further increased. It can be reliably suppressed.

  Further, the waiting time can be omitted. However, if control is performed so that combustion and ignition are started only after a predetermined waiting time at a high temperature, even when the responsiveness of the intake valve 21 is not sufficient, the combustion in a state where the air in the cylinder 11 is sufficiently suppressed. Thus, the occurrence of self-ignition is more reliably suppressed.

  The geometric compression ratio of the cylinder 11 is not limited to the above. However, in a high compression ratio engine, the work required for compression is large, the startability is likely to deteriorate, and self-ignition tends to occur. Therefore, it is effective if the present invention is used for an engine having a geometric compression ratio of 13.

  Specific values such as T1 and T2 are not limited to the above.

  Further, the detailed structure of various actuators is not limited to the above.

1 is a schematic view of an overall structure of an engine system according to the present invention. It is a schematic sectional drawing of the intake camshaft phase variable mechanism used for the engine system shown in FIG. FIG. 3 is a schematic front view of a planetary gear device in the intake camshaft phase varying mechanism shown in FIG. 2. FIG. 3 is a schematic front view of an electromagnetic actuator in the intake camshaft phase varying mechanism shown in FIG. 2. It is a figure for demonstrating the relationship between the closing timing of an intake valve, and air filling amount. It is a flowchart for demonstrating the control procedure of the control method which concerns on this invention. It is explanatory drawing for demonstrating the relationship between engine cooling water temperature, the closing timing of an intake valve, and the energization amount to an intake camshaft phase variable mechanism. It is explanatory drawing for demonstrating the relationship between engine cooling water temperature and waiting time. It is a figure which shows the example of control of each actuator in a normal driving | running condition. It is a figure which shows the example of control of each actuator at the time of high temperature.

1 Engine Body 11 Cylinder 14 Crankshaft 17 Combustion Chamber 21 Intake Valve (Intake Valve)
22 Exhaust valve 31 Camshaft 32 Intake camshaft phase variable mechanism (cam phase variable mechanism)
57 Throttle valve 100 Engine controller (control means)

Claims (8)

A cylinder that houses a reciprocating piston and forms a combustion chamber, a crankshaft connected to the piston, a camshaft that rotates in synchronization with the crankshaft, and air that is introduced into the cylinder passes therethrough. An internal combustion engine having an intake passage and an intake valve that reciprocates in response to rotation of the camshaft and blocks air inflow from the intake passage into the cylinder;
A cam phase variable mechanism that changes a rotation phase of the camshaft with respect to the crankshaft by supplying power and changes a closing timing of the intake valve ;
Control means for controlling the power supplied to the cam phase variable mechanism ,
The control means increases the power supplied to the cam phase variable mechanism immediately after the internal combustion engine is started,
The cam phase variable mechanism is configured to change a rotation phase of the camshaft with respect to the crankshaft in a state where the power is cut off, and to close the rotation timing of the intake valve into the cylinder when the internal combustion engine is started. The phase corresponds to the time when the amount of introduced air becomes maximum, and the closing timing of the intake valve is changed in a direction in which the amount of introduced air into the cylinder decreases as the supplied power increases. An internal combustion engine system. The internal combustion engine system according to claim 1,
An internal combustion engine system, wherein the power supplied to the cam phase variable mechanism is electric power. The internal combustion engine system according to claim 1 or 2,
The closing timing of the intake valve in a state where the power to the cam phase variable mechanism is cut off is the most advanced timing of the variable range of the closing timing of the intake valve changed by the cam phase variable mechanism. An internal combustion engine system. An internal combustion engine system according to any one of claims 1 to 3 ,
The internal combustion engine system, wherein the control means cuts off power supply to the cam phase variable mechanism when the internal combustion engine is started. An internal combustion engine system according to any one of claims 1 to 4 ,
An internal combustion engine system, wherein a geometric compression ratio of cylinders of the internal combustion engine is 13 or more. A cylinder that houses a reciprocating piston and that forms a combustion chamber, an intake passage through which air introduced into the cylinder passes, and an intake valve that blocks inflow of air from the intake passage into the cylinder A control method for an internal combustion engine comprising:
A step in the stopped state of the internal combustion engine, the closing timing of the intake valve, the introduction of air into the cylinder at the start of the internal combustion engine is Gosei the time of maximum,
When the internal combustion engine is started, when the temperature of the internal combustion engine is higher than a preset reference temperature, the closing timing of the intake valve is set to be less than the reference temperature. Controlling the time when the amount of introduction is small, rotating the internal combustion engine a predetermined number of times in a state where combustion in the combustion chamber is not performed, and then starting combustion in the combustion chamber; ,
Wherein immediately after the start of the internal combustion engine, an internal combustion engine which comprises the steps of said closing timing of the intake valve, which control braking to time the introduction of air into the cylinder is smaller than at start Control method. A control method for an internal combustion engine according to claim 6 ,
When the power is supplied, the rotation phase of the camshaft that rotates synchronously with the crankshaft connected to the piston and reciprocates the intake valve is changed with respect to the crankshaft, and the closing timing of the intake valve is set. Using the cam phase variable mechanism to change,
Oite during startup of the internal combustion engine, wherein when the temperature of the internal combustion engine is lower than or equal to the reference temperature which is set in advance, a control method for an internal combustion engine, characterized by interrupting the power to the variable cam phase mechanism. A control method for an internal combustion engine according to claim 7 ,
Using flow area changing means capable of changing the flow area of the intake passage,
Immediately after starting the internal combustion engine, the flow passage area changing means enlarges the flow passage area of the intake passage.

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