JP2009203818A - Control method of internal combustion engine and internal combustion engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of an internal combustion engine capable of securing starting performance. <P>SOLUTION: The control method performs a process in which the larger a target air filling amount CE<SB>D</SB>becomes, the earlier an intake valve 21 is closed, a process of controlling the valve closing timing IVC of the intake valve 21 to most-retarded timing by most retarding a rotation phase of a camshaft 31 with respect to a crankshaft 14 accompanied by the stop of the internal combustion engine 1, a process of, at the starting of the internal combustion engine 1 when a given condition beforehand set is established, controlling at least the valve closing timing IVC of the intake valve 21 to an advance side more than when the given condition is not established by advancing the rotation phase more than when the given condition is not established, and a process of, a the starting of the internal combustion engine 1, starting fuel supply into a combustion chamber 17 after the crankshaft 14 is forcibly rotated for a given period of time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control method for an internal combustion engine 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 has a variable valve device that changes the valve closing timing of the intake valve by changing the rotation phase of the camshaft with respect to the crankshaft. The variable valve device is driven to start the internal combustion engine. A system that changes the closing timing of the intake valve depending on the engine temperature is disclosed. In this system, the closing timing of the intake valve when the internal combustion engine is stopped is set to the most retarded timing at which the amount of air introduced into the cylinder is minimized, and the effective compression ratio of the engine is kept low. This suppresses the occurrence of abnormal combustion such as self-ignition during start-up. On the other hand, in this system, when the engine temperature is low at the time of starting, the rotational phase of the camshaft with respect to the crankshaft is changed so as to change the closing timing of the intake valve to the advance side. The amount of air is secured, that is, startability is secured.
JP 2007-113440 A

  When the rotational phase of the camshaft relative to the crankshaft is changed, a certain amount of time is required until the change amount reaches a predetermined amount. However, in the conventional method, this time is not taken into account, and as a result of supplying fuel into the cylinder in a state where the closing timing of the intake valve is not sufficiently changed to the advance side, the fuel amount and the air The amount may become unbalanced and startability may deteriorate, and exhaust properties may deteriorate.

  In view of such circumstances, an object of the present invention is to provide an internal combustion engine system capable of improving startability and exhaust properties 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 the rotation of the camshaft and blocks the inflow of air from the intake passage into the cylinder. An internal combustion engine control method capable of changing a rotational phase of the camshaft with respect to the crankshaft, wherein a larger target air filling amount that is a target value of an air amount introduced into the cylinder increases. A step of advancing the rotational phase relative to the crankshaft, and as the internal combustion engine stops, When the predetermined phase condition is satisfied at the time of starting the internal combustion engine, the step of forcibly rotating the crankshaft at the time of starting the internal combustion engine, and the time of starting the internal combustion engine, A step of advancing the rotational phase of the camshaft relative to the crankshaft relative to when the predetermined condition is not satisfied, and at the start of the internal combustion engine, the crankshaft is forcibly rotated for a predetermined period and then moved to the combustion chamber. A control method for an internal combustion engine, comprising the step of starting the fuel supply.

  In this control method, when the predetermined condition is not satisfied, the rotation phase of the camshaft with respect to the crankshaft is most retarded so that the closing timing of the intake valve is controlled to the most retarded timing, When the predetermined condition is satisfied, the rotation phase of the intake camshaft 31 with respect to the crankshaft 14 is controlled to the advance side, so that the closing timing of the intake valve is controlled to the advance side. It can be changed to an appropriate state according to conditions. In particular, in this method, fuel supply to the combustion chamber is started after the crankshaft has been forcibly rotated for a predetermined period, and the rotation phase of the camshaft with respect to the crankshaft has been sufficiently changed so that the intake valve is sufficiently Since the fuel is supplied in a state where the amount of air corresponding to the amount of fuel is present in the cylinder, it is possible to ensure the starting torque and improve the exhaust performance while ensuring the startability. In this method, the intake valve is controlled to be closed earlier as the target air filling amount increases, and the amount of air introduced into the cylinder is appropriately controlled without increasing pump loss due to throttle valve throttling. It is possible to increase the operating efficiency of the internal combustion engine.

  Here, when the temperature of the internal combustion engine is low, the viscosity of the lubricating oil is high and the frictional resistance against the rotation of the internal combustion engine is large. Therefore, if the predetermined condition is a condition that the temperature of the internal combustion engine is lower than a preset first temperature, and the valve closing timing of the intake valve is controlled to an advance side when the temperature of the internal combustion engine is low, the friction resistance Therefore, it is possible to secure an air amount sufficient to increase the rotational speed of the internal combustion engine against this, and to improve the low-temperature startability (claim 2).

  Further, when the temperature of the internal combustion engine is lower than a second temperature lower than the preset first temperature, the rotational phase of the camshaft with respect to the crankshaft may be advanced most. Item 3).

  In this case, after starting the internal combustion engine, after the rotational speed of the internal combustion engine exceeds a predetermined rotational speed set in advance, the step of controlling the rotational phase of the camshaft relative to the crankshaft to the retard side. Furthermore, it is preferable to include (Claim 4).

  That is, if the rotational phase of the camshaft relative to the crankshaft is maintained in the most advanced state, the amount of air introduced into the cylinder may become excessive. Therefore, as described above, when the rotational speed of the internal combustion engine exceeds a predetermined rotational speed set in advance, the rotational speed increases if the rotational phase of the camshaft with respect to the crankshaft is controlled to the retard side. While the amount of air can be secured until this is done, it is possible to suppress an excessive increase in the rotational speed after the rotational speed has stabilized.

  In the present invention, at the time of starting the internal combustion engine, the lower the temperature of the internal combustion engine, the more the rotational phase of the camshaft with respect to the crankshaft is controlled to the advance side, and the lower the temperature of the internal combustion engine is, It is preferable that the predetermined period is set longer (Claim 5).

  In this method, as the temperature of the internal combustion engine is low and the required amount of air in the cylinder is increased, the closing timing of the intake valve is controlled to advance, so that appropriate air in the cylinder according to the temperature of the internal combustion engine. The amount will be secured. In addition, the predetermined period is set longer according to the temperature of the internal combustion engine, and the advance amount of the valve closing timing is largely controlled by the low temperature, and accordingly, the air amount in the cylinder is predetermined. The start time of fuel supply will be delayed in response to the longer time to reach the amount, so the ratio of fuel amount to air amount at the start of combustion should be in a more appropriate state Can do.

  In the present invention, the internal combustion engine includes a cam phase variable mechanism that changes a rotation phase of the camshaft with respect to the crankshaft when power is supplied, and the cam phase variable mechanism includes the power to be supplied. It is preferable that the rotational phase of the camshaft with respect to the crankshaft is advanced as the value of is larger, while the rotational phase of the camshaft with respect to the crankshaft is most retarded when the power is cut off.

  In this way, it is not necessary to supply power to the cam phase variable mechanism in a state where the predetermined condition is not satisfied, and power for rotating the internal combustion engine by the starting means such as a starter motor, that is, power for cranking. Since it is possible to ensure sufficient, startability is improved.

  According to another aspect of the present invention, a cylinder that houses a reciprocating piston and forms a combustion chamber, a crankshaft connected to the piston, and a camshaft that rotates in synchronization with the crankshaft An internal combustion engine having an intake passage through which air introduced into the cylinder passes, and an intake valve that reciprocates in accordance with the rotation of the camshaft and blocks inflow of air from the intake passage into the cylinder A cam phase variable mechanism capable of changing a rotation phase of the camshaft with respect to the crankshaft by supplying power and changing at least a closing timing of the intake valve; and forcibly rotating the crankshaft. A motor, a fuel supply means capable of supplying fuel to the combustion chamber, and a control means, wherein the control means is a measure of the amount of air introduced into the cylinder. The rotational phase of the camshaft with respect to the crankshaft advances as the target air charge amount that is a value increases, and the rotational phase of the camshaft with respect to the crankshaft is the most retarded when the internal combustion engine is stopped. The cam phase variable mechanism is controlled, and the motor is controlled to forcibly rotate the crankshaft when the internal combustion engine is started. When the internal combustion engine is started, a preset predetermined condition is satisfied. The cam phase variable mechanism is controlled so that the rotational phase of the cam shaft with respect to the crank shaft advances more than when the predetermined condition is not satisfied, and when the internal combustion engine is started, the crank shaft The fuel supply unit is configured to start the fuel supply to the combustion chamber after being forced to rotate for a predetermined period. The internal combustion engine system, wherein is provided to control the (claim 7).

  In this internal combustion engine control system, the control means controls the closing timing of the intake valve to the most retarded timing when the predetermined condition is not satisfied, while closing the intake valve when the predetermined condition is satisfied. Since the timing is controlled to the advance side, the amount of air in the cylinder can be changed to an appropriate state according to the condition. In particular, in the present system, fuel supply to the combustion chamber has started after the crankshaft has been forcibly rotated for a predetermined period, and the rotation phase of the camshaft with respect to the crankshaft has been sufficiently changed so that the intake valve is sufficiently Since the combustion is started in a state where the amount of air corresponding to the amount of fuel is present in the cylinder, it is possible to realize an improvement in startability and an improvement in exhaust performance associated with securing of the start torque. Also, in this system, the intake valve is controlled to close earlier as the target air filling amount increases, and the amount of air introduced into the cylinder is appropriately controlled without increasing pump loss due to throttle valve throttling. It is possible to increase the operating efficiency of the internal combustion engine.

  The camshaft phase varying mechanism is configured to advance the rotational phase of the camshaft with respect to the crankshaft as the supplied power increases, and when the power is cut off, It is preferable that the rotational phase of the camshaft with respect to the crankshaft is most retarded.

  In this way, it is not necessary to supply power to the cam phase variable mechanism when the predetermined condition is not satisfied, and sufficient power for rotating the internal combustion engine, that is, power for cranking is secured by the motor. Therefore, startability is improved.

  The power supplied to the cam phase variable mechanism includes, for example, electric power (claim 9).

  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 12 by a journal, a bearing or the like. In the engine main body 1, the crankshaft 14 is forcibly rotated by a starter motor (motor) (not shown) at the time of starting.

  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 each have an intake camshaft (camshaft) 31 and an exhaust camshaft 41. 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 intake camshaft 31 and the exhaust camshaft 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) 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 intake 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, 35b at the most retarded angle position and the most advanced angle position are set as one set, and a total of two sets of stoppers 35a, 35b are provided at intervals. It has been.

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

  In a compressed state, the return spring 38 is stretched between one of the most advanced angle position stoppers 35b and the arm 36b facing the stopper, and the urging force of the return spring 38 causes the arm to move. 36b is biased toward the most retarded angle position stopper 35a.

  The electromagnet 37 is attached to the most advanced angle position stopper 35b on the opposite side to the return spring 38, and is provided on the end of the most advanced 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 advanced position stopper 35b.

In the intake camshaft phase variable mechanism 32 configured as described above, when no electric power is supplied from the battery or the like to the intake camshaft phase variable mechanism 32 and the electromagnet 37 of the electromagnetic actuator 34 is not excited, The core 36 is held at the most retarded position where the arm 36b contacts the most retarded position stopper 35a by the urging force of the return spring 38. That is, the valve timing of the intake valve 21 is maintained at the most retarded 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 camshaft 31. As a result, the valve timing of the intake valve 21 is controlled to the advance 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 intake camshaft 31 is detected by cam phase sensor 39, and its signal θ _{VCT_A} is transmitted to engine control means 100.

Further, in the present embodiment, the most retarded angle position and the most advanced angle position are set so that the closing timing of the intake valve 21 is changed within the range of the retard angle side from the bottom dead center. More specifically, as shown in FIG. 5, the closing timing of the intake valve 21 is filled with the air in the combustion chamber 17 as the advance angle is between the most advanced timing θ _a and the most retarded timing θ _z. The range is set such that the amount CE increases. Further, the most retarded timing theta _z, said the most retarded angle close timing of the intake valve 21 in a normal start to be started between the warm engine body 1 comprising at T2 than the temperature T _ENG of the engine coolant is below When controlled at time θ _z , the air filling amount CE in the combustion chamber 17 satisfies the amount of air necessary for burning the amount of fuel capable of generating the torque necessary for starting. Is set to a value.

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 for adjusting the intake air 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 drives the throttle valve 57 so that the opening TVO becomes the target throttle opening TVO _D calculated by the engine controller 100 described later of 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 this 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 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, and thereby the flow rate of the EGR gas is reduced. 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.

  Further, a fuel injection valve (fuel supply means) 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. From the crank angle pulse signal, the rotational speed (rotational speed) N _ENG of the engine body 1 is calculated.

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 control flag is 1 (step S3). The starting control flag _{F START,} the following steps S4~ a flag indicating whether the state should be carried out starting control to step _{S16, F START} = 1 the starting control performed _{F START} = 0 In the normal control Is done. However, F _START = 0 when it is determined in step S2 that the starter motor is being driven indicates that the starter motor is started and the starter motor is started to be driven.

  If the determination in step S3 is YES, that is, if the current state is not at the start of starting and is in a state where starting control is performed, 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 control flag F _START 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, in a normal state where the temperature T _ENG of the engine coolant is equal to or higher than T1, the target value θ _{VCT_D} of the closing timing IVC is set as the most retarded angle timing θ _z , and the engine In the case of cold start when the temperature T _{ENG of the} cooling water is T2 or less, the target value θ _{VCT_D} is set to the _{most advanced} angle timing θ _a, and when the temperature T _ENG of the engine cooling water is T1 to T2, The target value θ _{VCT_D} is set as _a timing for advancing in proportion to a decrease in the engine coolant temperature T _ENG between the most retarded angle timing θ _z and the _{most advanced} angle timing θ _a . The T1 is, for example, 10 ° C., and the T2 is, for example, −20 ° C.

Here, as described above, the closing timing IVC of the intake valve 21 a sufficient amount of air is introduced into the cylinder 11 while being controlled to the most retarded timing theta _z. Moreover, in the engine body 1, the closing timing IVC of the intake valve 21, the power to the intake camshaft phase varying mechanism 32 is held the most retarded timing theta _z in a state not being supplied. Therefore, when controlling the closing timing IVC of the intake valve 21 to the most retarded timing theta _z, as shown in FIG. 7, there is no need to supply power to the intake camshaft phase varying mechanism 32, the starter motor Startability is enhanced by ensuring sufficient power to be supplied. Therefore, in this embodiment, the engine cooling water temperature T _ENG is relatively high (T _ENG ≧ T1), and the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is set to the maximum value at the normal start time when the operation frequency is high. and retarded timing theta _z, by controlling the closing timing IVC of the intake valve 21 to the most retarded timing theta _z, enhance the startability.

On the other hand, when the temperature of the engine body 1 is low, the viscosity of the lubricating oil is high, the frictional resistance against rotation of the engine body 1 is large, and sufficient torque is required. Therefore, under a condition where the temperature T _ENG of the engine coolant is relatively low (T _ENG <T1), the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is set to an advance side with respect to the most retarded timing θ _z , By controlling the closing timing IVC to the advance side, the amount of air introduced into the cylinder 11 is ensured, and a sufficient amount of fuel can be supplied to ensure startability.

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 temperature T _ENG of the engine coolant is equal to or higher than T1, the waiting time t _{START is set} to 0, and when the temperature T _ENG of the engine coolant is equal to or lower than T2. When the waiting time t _START is set to the predetermined time C2 and the engine cooling water temperature T _ENG is T1 to T2, the waiting time t _START is set between 0 and the predetermined time C2 to the engine cooling water temperature T _ENG . The time becomes longer in proportion to the decrease.

As described above, under the condition that the engine coolant temperature T _ENG is relatively low (T _ENG <T1), the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 is advanced from the most retarded angle timing θ _z. By controlling the closing timing IVC to the advance side, the amount of air introduced into the cylinder 11 is increased to ensure startability. However, the response of the intake camshaft phase varying mechanism 32 is not sufficient, and in practice, it is difficult to sufficiently advance the closing timing IVC of the intake valve 21 immediately at the start.

Therefore, in the engine controller 100, under the cold start condition where the engine coolant temperature T _ENG is equal to or less than T1, the fuel is injected into the combustion chamber 17 and combusted only after the waiting time _{tSTART has} elapsed from the start of the start. By generating a spark in the chamber 17, the closing timing IVC of the intake valve 21 is controlled so that combustion does not start when the intake valve 21 is not sufficiently advanced and the air amount is insufficient. In this way, the combustion starts only when the amount of air commensurate with the amount of fuel is secured, so that the exhaust performance can be improved while improving the startability. In particular, as described above, the waiting time t _START is set in accordance with the change in the temperature T _ENG of the engine coolant, so that the waiting time t _START and the advance amount of the closing timing IVC of the intake valve 21 correspond to each other. Therefore, the fuel amount and the air amount can be more appropriately set to an appropriate state.

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 to increase as the engine coolant temperature T _ENG decreases.

If the determination in step S2 is NO, that is, if the starter motor is not being driven, the current state is immediately after the start and the engine speed 1 _ENG has not yet increased sufficiently. Determine if it exists. Specifically, it is determined whether or not the start control flag F _START is maintained at 1 and whether or not the rotational speed N _ENG of the engine body 1 is equal to or lower than a predetermined reference rotational speed N1 (step S16). If this determination is YES, that is, if the engine speed N _ENG has not yet exceeded the reference speed N1 immediately after starting, the process proceeds to step S12 as it is. At this time, the fuel injection amount FP, ignition timing S1, and the target throttle opening TVO _D is maintained at the value calculated in step S10 and S11, so that the control during startup is performed. Thus, the air amount and the fuel amount are maintained in an appropriate state until the engine speed N _ENG is stabilized, so that the engine speed can be stabilized at an early stage while maintaining good exhaust performance. . N1 is, for example, about 500 rpm.

On the other hand, if the determination in step S16 is NO, that is, not immediately after starting, or immediately after starting but the engine speed N _ENG is sufficiently increased, the start control flag F _START is set. The fuel injection amount FP, the ignition timing SA, the target throttle opening TVO _D , and the target value θ _{VCT_D} of the closing timing IVC of the intake valve 21 are calculated (step S21).

Target throttle opening TVO _D in the normal operation is set larger than the starting target value 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. Specifically, in the normal operation, as shown in FIG. 9, the throttle opening TVO is set in a region where the target air charge amount CE _D that is the target value of the air charge amount CE in the combustion chamber 17 is not more than a predetermined value. while controlled by the opening side with an increase in the target air charge amount CE _D, the target air charge amount CE _D is in a region greater than a predetermined value is controlled to a constant value regardless of the target air charge amount CE _D.

Also, the closing timing IVC of the intake valve 21 during normal operation the is set to the retard side than the most advanced timing theta _a, when the temperature T _ENG of the engine cooling water is at least the T2 or less, the starting Thereafter, the closing timing IVC of the intake valve 21 is controlled to the retard side when the engine speed N _ENG becomes N1 or more and the rotation of the engine body 1 is stabilized. And thus, by the closing timing IVC of the intake valve 21 is controlled to the retard side from the most advanced timing theta _a, so that the amount of air charge is excessive is avoided, the rotation of the engine body 1 An excessive increase in the number N _ENG is suppressed.

Specifically, the normal closing timing IVC of the intake valve 21 during operation, as shown in FIG. 10, the target air charge amount CE _D is a predetermined value or less in the region, the target air charge amount CE _D and the engine speed while being controlled to a constant value regardless of the N _ENG, the target air charge amount CE _D is the larger region than a predetermined value, is controlled to the advance side with an increase in the target air charge amount CE _D. Then, if in this way the target air charge amount CE _D is controlled by the closing timing IVC of the intake valve 21, the pumping losses caused by throttling the throttle valve 57 is suppressed, air charge in the cylinder 11 is properly As a result, the operating efficiency of the engine body 1 is increased.

After each target value is calculated, the process proceeds to step S12, and each actuator is driven based on the calculated target value and the like. 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 air-fuel mixture composed of a required amount of air and fuel is ignited and burned at an appropriate time, so that output torque required by the engine body 1 is generated from the crankshaft 14.

The behavior of each actuator based on the above control procedure is shown in FIGS. 11, the temperature T _ENG of the engine coolant indicates the behavior of the normal start-up is not less than T1, FIG. 12 shows the behavior at cold start is the temperature T _ENG of the engine cooling water is lower than T2.

As shown in FIG. 11, under normal operating conditions, the engine speed N is maintained while the starter motor is ON, that is, while the starter motor is driven, and after the start control flag F _START is 1 and the starter motor is turned on. until _ENG exceeds the N1, together with the closing timing IVC is controlled to the timing retarded angle theta _z of the intake camshaft phase varying mechanism 32 intake valve 21 is not powered on, the throttle opening TVO is The starting target value TVO _START is controlled. On the other hand, when the starter motor is OFF and the engine speed N _ENG exceeds N1, the start control flag F _START becomes 0, the closing timing IVC of the intake valve 21 is controlled to the advance side, and the throttle opening TVO Is controlled to open side. Also, under this operating condition, fuel injection and ignition are started at the same time as the starter motor is turned on. Here, in the graph of the closing timing IVC, the solid line indicates the target value, and the broken line indicates the actual timing.

On the other hand, at the time of cold start, as shown in FIG. 12, when the starter motor is turned on and power is supplied to the intake camshaft phase varying mechanism 32, the closing timing IVC of the intake valve 21 is advanced. Be controlled. In particular, the temperature _{T ENG} of the engine cooling water is above T2 In the following, the closing timing IVC of the intake valve 21 is controlled to the most advanced timing theta _a. The value of the closing timing IVC is maintained until the engine speed N _ENG exceeds N1.

Further, at the time of cold start, fuel injection and ignition are prohibited during a predetermined waiting time t _START from when the starter motor is turned on until the waiting time counter C _START becomes 0, and after the waiting time t _START Fuel injection and ignition are performed for the first time. The throttle opening TVO is controlled to a relatively large starting target value TVO _START in accordance with the engine temperature _TENG . When the starter motor is turned off and the engine speed N _ENG exceeds N1, the closing timing IVC of the intake valve 21 is controlled to the retard side, and the throttle opening TVO is controlled to the opening side.

With the control as described above, in the present engine system, an appropriate amount of air can be introduced into the cylinder 11 in accordance with the engine coolant temperature _TENG, and startability can be ensured.

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

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 as the rotational speed after starting increases by a predetermined value or more, and the amount of air introduced into the cylinder 11 is reduced, excess air will enter the cylinder 11. Can be avoided and an excessive increase in the rotational speed N _ENG of the engine body 1 can be suppressed.

  The geometric compression ratio of the cylinder 11 is not limited to the above.

  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 target value of the throttle valve in a normal driving | running condition. It is a figure which shows the target value of the closing timing of an intake valve in a normal driving | running condition. It is a figure which shows the example of control of each actuator at the time of normal starting. It is a figure which shows the example of control of each actuator at the time of cold start.

Explanation of symbols

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

Claims (9)

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 intake passage and an intake valve that reciprocates in response to rotation of the camshaft and blocks air flow from the intake passage into the cylinder, and changes a rotation phase of the camshaft with respect to the crankshaft. A control method for a possible internal combustion engine comprising:
The step of advancing the rotational phase of the camshaft with respect to the crankshaft as the target air filling amount, which is a target value of the air amount introduced into the cylinder, increases;
A step of most retarding the rotational phase of the camshaft with respect to the crankshaft, with the stop of the internal combustion engine;
Forcibly rotating the crankshaft when starting the internal combustion engine;
A step of advancing the rotational phase of the camshaft relative to the crankshaft with respect to the crankshaft when the predetermined condition is satisfied when the internal combustion engine is started;
And a step of starting fuel supply to the combustion chamber after the crankshaft is forcibly rotated for a predetermined period when the internal combustion engine is started. A control method for an internal combustion engine according to claim 1,
The control method for an internal combustion engine, wherein the predetermined condition is satisfied if the temperature of the internal combustion engine is lower than a preset first temperature. A control method for an internal combustion engine according to claim 2,
A step of advancing the rotational phase of the camshaft relative to the crankshaft when the temperature of the internal combustion engine is lower than a preset second temperature lower than the first temperature at the time of starting the internal combustion engine; A control method for an internal combustion engine, further comprising: A control method for an internal combustion engine according to claim 3,
At the time of starting the internal combustion engine, if the temperature of the internal combustion engine is lower than the second temperature, after the internal combustion engine is started, after the rotational speed of the internal combustion engine exceeds a predetermined rotational speed, A control method for an internal combustion engine, further comprising a step of controlling a rotation phase of the camshaft with respect to the crankshaft to a retarded angle side. A control method for an internal combustion engine according to claim 2,
At the time of starting the internal combustion engine, the lower the temperature of the internal combustion engine, the more the rotational phase of the camshaft relative to the crankshaft is controlled to the advance side,
The control method for an internal combustion engine, wherein the predetermined period is set longer as the temperature of the internal combustion engine is lower. A control method for an internal combustion engine according to any one of claims 1 to 5,
The internal combustion engine includes a cam phase variable mechanism that changes a rotational phase of the camshaft with respect to the crankshaft when power is supplied;
The cam phase variable mechanism advances the rotational phase of the camshaft with respect to the crankshaft as the supplied power increases, while the camshaft with respect to the crankshaft is most retarded when the power is cut off. A control method for an internal combustion engine, characterized in that it is set to do so. 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 capable of changing a rotation phase of the camshaft with respect to the crankshaft by supplying power and changing at least a closing timing of the intake valve;
A motor capable of forcibly rotating the crankshaft;
Fuel supply means capable of supplying fuel to the combustion chamber;
Control means,
The control means makes the rotational phase of the camshaft relative to the crankshaft advance as the target air filling amount, which is the target value of the air amount introduced into the cylinder, increases, and stops the internal combustion engine. And the cam phase variable mechanism is controlled so that the rotational phase of the cam shaft with respect to the crankshaft is most retarded,
Controlling the motor to forcibly rotate the crankshaft when starting the internal combustion engine;
When the internal combustion engine is started, the cam phase variable mechanism is configured such that when a predetermined condition set in advance is satisfied, the rotational phase of the camshaft relative to the crankshaft is advanced more than when the predetermined condition is not satisfied. Control
An internal combustion engine system that controls the fuel supply means so that fuel supply to the combustion chamber is started after the crankshaft is forcibly rotated for a predetermined period when the internal combustion engine is started. The internal combustion engine system according to claim 7,
The camshaft phase varying mechanism is configured to advance the rotational phase of the camshaft with respect to the crankshaft as the supplied power increases, and when the power is cut off, An internal combustion engine system configured to retard the rotational phase of the crankshaft with respect to the crankshaft. An internal combustion engine system according to claim 8,
An internal combustion engine system, wherein power supplied to the camshaft phase varying mechanism is electric power.

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