JP2018200006A - Controller of internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine that reduces a load at the start and enables a good start while reducing THC. An opening and closing timing of an intake valve is set to the most retarded angle at the start of cranking by driving a starter motor 15, and an ignition control unit 42 performs initial combustion in any of a plurality of combustion chambers after the start of cranking. A start load reducing unit 41 for controlling the electric actuator M of the valve opening / closing timing control mechanism is provided so that the opening / closing timing of the intake valve is displaced to the advance side before performing the operation. [Selection] Figure 2

Description

  The present invention relates to a control device for an internal combustion engine.

  Patent Document 1 discloses a decompression device that reduces the compression pressure by opening the exhaust valve by lifting a certain amount to open at least the in-cylinder pressure during the compression stroke. The decompression device is brought into a decompressed state when the engine is started. The technology to perform cranking is described.

  In Patent Document 2, a valve opening / closing timing control mechanism (a variable valve device in the literature) that controls an intake valve when the engine is stopped is fixed to the advance side, and when the engine is started, the variable valve device is moved to the advance side. A technique for securing startability in a low-temperature environment by fixing to the above is described.

  Patent Document 3 discloses a technique for controlling a valve opening / closing timing control mechanism (in the literature, a variable valve mechanism) so as to advance the opening / closing timing of an intake valve when an internal combustion engine starts at a temperature lower than a predetermined temperature. Have been described.

JP2015-218629A JP 2000-257453 A JP2013-53610A

  Reducing the load acting on the crankshaft at the start of the internal combustion engine reduces the power consumption of the starter motor at the time of cranking and enables a higher speed of the crankshaft, leading to a good start. In particular, in a very low temperature environment, the viscosity of the lubricating oil is high and the startability is lowered, so it is important to reduce the load acting on the crankshaft.

  In order to solve such problems, Patent Document 1 reduces the load during cranking by performing decompression, and Patent Documents 2 and 3 control the valve opening / closing timing control device of the intake valve in the advance direction. By doing so, the pump loss is reduced, or the working angle of the intake valve is reduced to improve the startability.

  However, in the case where decompression is performed as in Patent Document 1, although the load at the time of cranking is reduced, the intake amount is small and the compression temperature is lowered, so that the amount of THC (unburned hydrocarbon) emission increases. Met.

  In addition, as in Patent Documents 2 and 3, in which the variable valve device is controlled to the advance phase, the compression temperature rises, so that it is effective in reducing THC (unburned hydrocarbon), but the load at the start Will greatly increase the power consumption. In particular, when the battery charge rate is low, cranking with the starter motor cannot be performed properly due to the load at the start, and the engine may not start smoothly or the engine may not be able to start. .

  For these reasons, there is a need for an internal combustion engine control device that reduces the load at the time of starting and enables good starting while reducing THC.

The present invention is characterized by an intake valve that opens and closes a combustion chamber in conjunction with rotation of a crankshaft, a starter motor that drives and rotates the crankshaft, an ignition control unit that ignites an air-fuel mixture in the combustion chamber, and an electric actuator An internal combustion engine comprising a valve opening / closing timing control mechanism for setting the opening / closing timing of the intake valve by driving
At the start of cranking by driving the starter motor, the opening / closing timing of the intake valve is set to the most retarded angle. After the cranking is started, the ignition control unit performs the first combustion in any of the plurality of combustion chambers. A starting load reducing unit for controlling the electric actuator of the valve opening / closing timing control mechanism so as to displace the opening / closing timing of the intake valve to the advance side before the operation is performed.

  FIG. 16 shows a timing chart of the experimental example. In the figure, the change in the engine speed after the start of cranking is shown in the upper part, and the change in the current value supplied to the starter motor after the start of cranking is shown in the lower part. In the figure, the intake timing by the valve opening / closing timing control mechanism is set to the most retarded angle, and the negative compression (for example, the setting in FIG. 7) is set by a solid line, and the intake timing is the most advanced. A broken line indicates a high compression ratio in which an overlap (for example, the setting shown in FIG. 8) is set at a corner.

  As can be understood from FIG. 16, when a compression stroke is first performed in a predetermined cylinder at the start of cranking, it is supplied to the starter motor in order to start the operation of the crankshaft and the piston in a stationary state. The current value is extremely large and the power consumption is maximized. In the first compression stroke, there is no significant difference between the current value and the rotational speed between the low compression ratio setting and the high compression ratio setting.

  After this, when compression is performed in the next cylinder (timing Z in the figure), the first current value Ca set for the low compression ratio is smaller than the second current value Cb set for the high compression ratio, and is low. The first rotation speed Ra set for the compression ratio is larger than the second rotation speed Rb set for the high compression ratio. This phenomenon can be similarly confirmed in the subsequent compression stroke. In this way, it is possible to confirm the effectiveness of suppressing the power consumption and increasing the rotation speed (rotation speed) by setting the intake timing to the most retarded angle (low compression ratio) by the valve opening / closing timing control mechanism during cranking.

For this reason, in this feature configuration, at the start of cranking, the start load reducing unit sets the intake valve opening and closing timing to the most retarded angle to reduce the load acting on the starter motor, and cranking while reducing power consumption Increase speed. In addition, the start load reducing unit increases the intake air amount by increasing the intake temperature and increasing the compression temperature by displacing the opening / closing timing of the intake valve to the advance side before the first combustion in the combustion chamber after the start of cranking. Combustion in a state where the increase in the amount is suppressed. In particular, since the valve opening / closing timing control mechanism is configured to set the opening / closing timing by the driving force of the electric actuator, for example, the valve opening / closing timing control mechanism is compared with a mechanism for setting the opening / closing timing with hydraulic oil supplied from a hydraulic pump driven by an internal combustion engine. Thus, it is possible to set the opening / closing timing appropriately by operating at high speed even when the internal combustion engine is started.
Therefore, a control device for an internal combustion engine that reduces the load at the time of start and enables a good start while reducing THC has been configured.

  As another configuration, the starting load reducing unit sets the opening / closing timing of the intake valve to the most retarded angle until a set time elapses from the start of cranking, and after the set time elapses, You may perform advance angle control which displaces opening and closing timing to an advance angle side.

  According to this, compression is performed in a predetermined cylinder by the start of cranking, and by setting a sufficient time in advance until compression is performed in the next cylinder, the first compression is performed in the predetermined cylinder by cranking. Can be set to shift the opening / closing timing of the intake valve from the most retarded angle to the advanced angle side.

As another configuration, the internal combustion engine has four or more cylinders, and a crank angle sensor that detects an angle of the crankshaft to detect a cylinder and an angle of an intake camshaft or an exhaust camshaft. With a cam angle sensor,
The start load reducing unit sets the opening / closing timing of the intake valve to the most retarded angle until it detects that the crankshaft has made a half rotation from the start of cranking based on the detection result of the crank angle sensor. Then, after this detection, advance angle control for displacing the intake valve to the advance side may be performed.

  For example, in a 4-cylinder internal combustion engine, when the crankshaft rotates 1/2, the camshaft rotates 1/4, so the compression of the first cylinder is complete. For this reason, the first compression is achieved by displacing the opening / closing timing of the intake valve from the most retarded angle to the advanced angle side after detecting that the crankshaft has made a half rotation based on the detection result of the crank angle sensor. After being performed, it is possible to set a control mode in which the opening / closing timing of the intake valve is displaced from the most retarded angle to the advanced angle side.

As another configuration, the internal combustion engine includes a crank angle sensor that detects an angle of the crankshaft to perform cylinder discrimination, and a cam angle sensor that detects an angle of an intake camshaft or an exhaust camshaft,
The starting load reducing unit until the detection of reaching the compression top dead center in any one of the plurality of cylinders based on the detection result of at least one of the crank angle sensor and the cam angle sensor The opening / closing timing of the intake valve may be set to the most retarded angle, and after this detection, advance control may be performed to displace the intake valve to the advance side.

  At a timing at which cylinder discrimination is possible, the crankshaft is at least half-turned. For this reason, when the compression top dead center is first reached in one of the cylinders due to cranking and the compression is completed in the next cylinder by cylinder discrimination, the opening / closing timing of the intake valve is changed from the most retarded angle to the advanced angle side. The control form can be set to be displaced. In particular, in this control mode, the switching timing can be switched based on the timing at which the compression top dead center is reached, so that the control can be performed with high accuracy.

As another configuration, the internal combustion engine includes a speed sensor capable of detecting a change in angular speed during rotation of the crankshaft,
The start load reducing unit keeps opening and closing timing of the intake valve until it detects that the angular velocity has increased after the angular velocity has been lowered by the speed sensor after the cranking has started, and that the angular velocity has reached the rising peak. The most retarded angle may be set, and after this detection, advance angle control may be performed to displace the intake valve to the advance angle side.

  When the internal combustion engine is stopped, the piston is normally in a position slightly before the compression top dead center in any cylinder. For this reason, when cranking is performed, the angular velocity of the crankshaft reaches a peak on the descending side at the timing when compression top dead center is reached in any cylinder, and thereafter the angular velocity starts to increase. Therefore, in this configuration, cranking is started, and after the first peak on the lower side of the angular velocity is detected by the speed sensor and the first peak on the higher side of the angular velocity is detected, the opening / closing timing of the intake valve is the latest. Displace from the angle to the advance side. As a result, a compression period in which the intake valve is open in any cylinder at the start is ensured, and the opening / closing timing of the intake valve is advanced from the most retarded angle after the first compression is performed in any cylinder. It is possible to set a starting form that suppresses TCM by being displaced to the side.

It is sectional drawing of an engine. It is a block part of a control system. It is sectional drawing of a valve opening / closing timing control mechanism. It is the IV-IV sectional view taken on the line of FIG. It is the VV sectional view taken on the line of FIG. It is a disassembled perspective view of a valve opening / closing timing control mechanism. It is a timing diagram which shows the opening and closing timing in the most retarded angle. It is a timing diagram which shows the opening and closing time in the most advanced angle. It is a flowchart of the engine starting routine of a 1st control form. It is a timing chart at the time of cranking by the 1st control form. It is a flowchart of the engine starting routine of the 2nd control form. It is a timing chart at the time of a crank in the 2nd control form. It is a flowchart of the engine starting routine of the 3rd control form. It is a flowchart of the engine starting routine of the 4th control form. It is a timing chart at the time of a crank in the 4th control form. It is a timing chart which shows the relationship between the rotation speed at the time of cranking, and an electric current value in an experiment example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Basic configuration]
As shown in FIGS. 1 and 2, an engine control device 40 that functions as an ECU for controlling an engine E as an internal combustion engine and a valve opening / closing timing control mechanism VT for setting an opening / closing timing of an intake valve Va of the engine E. Is configured.

  The engine E (an example of an internal combustion engine) shown in FIGS. 1 and 3 is assumed to be provided in a vehicle such as a passenger car. In this engine E, a cylinder head 3 is connected to an upper portion of a cylinder block 2 that supports a crankshaft 1, pistons 4 are slidably accommodated in a plurality of cylinder bores formed in the cylinder block 2, and the piston 4 is connected to a connecting rod. 5 is connected to the crankshaft 1 to form a four-cycle type.

  In this engine E, # 1 cylinder, # 2 cylinder, # 3 cylinder, # 4 cylinder (shown as # 1, # 2, # 3, # 4 in FIG. 3) from one end to the other. The combustion chamber is formed between the piston 4 and the cylinder head 3 in the internal space of the cylinder.

  The cylinder head 3 is provided with an intake valve Va that is opened when the combustion chamber is inhaled and an exhaust valve Vb that is opened when the combustion gas is discharged from the combustion chamber, and an intake valve that controls the intake valve Va is provided above the cylinder head 3. A camshaft 7 and an exhaust camshaft 8 that controls the exhaust valve Vb are provided. The timing chain 6 is wound around the output sprocket 1S of the crankshaft 1, the sprocket 21S of the drive case 21 of the valve opening / closing timing control mechanism VT, and the drive sprocket 8S of the exhaust camshaft 8.

  Further, the cylinder head 3 is provided with an injector 9 and a spark plug 10 for injecting fuel into the combustion chamber. An intake manifold 11 that supplies air to the combustion chamber via an intake valve Va and an exhaust manifold 12 that sends combustion gas from the combustion chamber via an exhaust valve Vb are connected to the cylinder head 3.

  As shown in FIG. 2, the engine E includes a starter motor 15 that is driven to rotate on the crankshaft 1, and a crank sensor 16 that can detect the rotation angle and the number of rotations per unit time at a position near the crankshaft 1. (An example of a crank angle sensor).

[Basic configuration: crank sensor and intake cam angle sensor]
As shown in FIGS. 1 and 2, the engine E includes an intake cam angle sensor 17 (an example of a cam angle sensor) that can detect the rotational phase of the intake camshaft 7. With this configuration, the opening / closing timing (valve timing) of the valve opening / closing timing control mechanism VT can be acquired based on the detection result of the crank sensor 16 and the detection result of the intake cam angle sensor 17. In this embodiment, the intake camshaft 7 is provided with a cam angle sensor. However, the exhaust camshaft 8 may be provided with a cam angle sensor when used for cylinder discrimination.

  In the engine E, the cylinder discrimination unit 44 of the engine control device 40 performs cylinder discrimination based on the detection signal of the crank sensor 16 and the detection signal of the intake cam angle sensor 17. In other words, as shown in FIG. 2, the crank sensor 16 has a disc portion 16D that rotates integrally with the crankshaft 1 and a crank sensor portion 16S that can detect a large number of tooth portions 16T formed on the outer periphery of the disc portion 16D. It consists of and. Reference points 16n that do not include the tooth portions 16T are formed at two locations on the outer periphery of the disk portion 16D, and these reference points are made to coincide with the top dead center TDC of a predetermined cylinder (for example, # 1 cylinder) ( The top dead center TDC and the bottom dead center BDC are the timings shown in FIGS. In the following description, both the top dead center and the compression top dead center are described as TDC.

  In the engine E, as shown in FIG. 3, the # 1 and # 4 cylinders simultaneously reach the top dead center TDC, and the # 2 and # 3 cylinders simultaneously reach the bottom dead center BDC. Further, the positional relationship is set so that one of the # 1 cylinder and the # 4 cylinder becomes the compression top dead center TDC and the other becomes the exhaust top dead center at the timing when the crank sensor unit 16S detects the reference point 16n. The position of the reference point 16n may be set so that the # 2 cylinder and the # 3 cylinder are at the top dead center TDC at the timing when the crank sensor unit 16S detects the reference point 16n.

  The disk portion 16D and the tooth portion 16T are integrally formed of a magnetic material, and by using a pick-up type as the crank sensor portion 16S, a large number of reference points 16n are used as a reference when the crankshaft 1 rotates. The tooth portion 16T is detected by the crank sensor portion 16S, and the rotation angle of the crankshaft 1 (an angle with reference to the reference point 16n) is obtained by counting in the engine control device 40 for each detection. Yes.

  As shown in FIG. 2, the intake cam angle sensor 17 includes a rotating body 17D that rotates integrally with the intake camshaft 7, and an intake cam sensor that detects four detection areas 17T formed in a sector shape on the outer periphery of the rotating body 17D. 17S. Further, the four detection regions 17T enable discrimination of four cylinders by making each length (peripheral length) different in a region where the entire circumference of the rotating body 17D is equally divided into four.

  The rotating body 17D and the detection region 17T are formed of a magnetic material, and a pickup type is used as the intake cam sensor portion 17S. When the intake cam sensor unit 17S detects the start end of the detection region 17T (detects an up edge) with the rotation of the intake camshaft 7, it starts counting the clock signal generated inside the engine control device 40, When the end portion of the detection region 17T is detected (down edge is detected), the count is ended, and the cylinder can be discriminated based on the count value (integrated value) at the end time.

  In the 4-cycle engine, when the crankshaft 1 rotates twice, the intake camshaft 7 and the exhaust camshaft 8 rotate once. Although it is possible to determine which of the four cylinders is at the top dead center from the angle of the crankshaft 1, it is impossible to distinguish between the compression top dead center and the exhaust top dead center. For this reason, the rotating body 17D of the intake cam angle sensor 17 is divided into four in the circumferential direction, the circumferences of the four detection areas 17T are made different, and these detection areas 17T are designated as # 1 cylinder, # 3 cylinder, # Corresponding to the four cylinders and the # 2 cylinder, the cylinder at the compression top dead center TDC can be discriminated based on the detection by the crank sensor unit 16S and the detection by the intake cam sensor unit 17S.

  In particular, the intake cam angle sensor 17 is configured to be able to detect the opening / closing timing (valve timing) of the valve opening / closing timing control mechanism VT. That is, for example, considering the situation where the valve opening / closing timing control mechanism VT is at the most retarded angle, the crank sensor at the detection timing when the end of one detection region 17T set in advance among the four detection regions 17T is detected. The count value of 16 is a fixed value. Therefore, when the relative rotation phase of the valve timing control mechanism VT (the relative rotation phase between the drive case 21 and the internal rotor 22 shown in FIG. 3) is displaced in the intermediate phase direction, the crank sensor 16 at the detection timing described above. The count value also changes, and the opening / closing timing can be detected from the amount of change (difference / offset value).

  The object provided with the rotating body 17D is not limited to the intake camshaft 7, but may be the internal rotor 22 of the valve opening / closing timing control mechanism VT.

[Basic configuration: Overview of engine control system]
The engine control device 40 functions as an ECU that controls the engine E, and includes a start control unit 41 that functions as a start load reducing unit, an ignition control unit 42, a phase control unit 43, and a cylinder determination unit 44. ing. The start control unit 41 controls the start of the engine E in a state where the load during cranking is reduced. The ignition control unit 42 controls the injector 9 and the spark plug 10 at the set timing to realize combustion. The phase control unit 43 sets the opening / closing timing (opening / closing timing) of the intake valve Va by controlling the phase control motor M of the valve opening / closing timing control mechanism VT. The cylinder discriminating unit 44 discriminates the stroke for each cylinder and enables the ignition order to be set. Details of the engine control device 40 and the control mode will be described later.

[Valve opening / closing timing control mechanism]
As shown in FIGS. 3 to 6, the valve opening / closing timing control mechanism VT includes a drive case 21 and an internal rotor 22, and the relative rotational phase thereof is set by the driving force of the phase control motor M as an electric actuator. A phase adjusting unit is provided.

  The drive case 21 has a sprocket 21 </ b> S formed on the outer periphery and is disposed coaxially with the rotational axis X of the intake camshaft 7. The internal rotor 22 is included so as to be rotatable relative to the drive case 21, and is connected and fixed to the intake camshaft 7 by a connecting bolt 23. A phase adjuster is disposed between the drive case 21 and the internal rotor 22, a front plate 24 is disposed at a position covering the opening of the drive case 21, and this is fastened to the drive case 21 with a plurality of fastening bolts 25. Yes.

  In this valve opening / closing timing control mechanism VT, the whole is rotated in the driving rotation direction S by the driving force from the timing chain 6 as shown in FIG. The direction in which the relative rotational phase of the internal rotor 22 with respect to the drive case 21 is displaced in the same direction as the drive rotation direction S by the driving force of the phase control motor M is referred to as the advance angle direction Sa, and the displacement in the opposite direction is delayed. This is referred to as the angular direction Sb. Note that the intake amount at the intake valve Va is increased by displacing the relative rotational phase in the advance angle direction Sa, and the intake amount is maximized at the most advanced angle phase shown in FIG. On the contrary, the intake amount at the intake valve Va is reduced by displacing the relative rotational phase in the retarding direction Sb, and the intake amount is minimized at the most retarded phase shown in FIG. When cranking is performed by setting the most retarded phase shown in FIG. 7, not only the intake amount is reduced, but also a compression period in which the intake valve Va is in an open state is ensured. Reduce the load.

[Valve opening / closing timing control mechanism: phase adjuster]
The phase adjustment unit includes a plurality of internal teeth 26T integrally formed on the inner periphery of the inner rotor 22, and includes a ring gear 26 arranged coaxially with the rotation axis X, and a plurality of meshes for meshing with the ring gear 26. And the inner gear 27 disposed coaxially with the eccentric shaft core Y in a posture parallel to the rotational shaft core X, and includes the eccentric cam body 28 and the joint portion J. .

  In this phase adjustment unit, the number of teeth of the outer tooth portion 27T of the inner gear 27 is smaller by one than the number of teeth of the inner tooth portion 26T of the ring gear 26.

  Further, the joint portion J is configured as an Oldham joint that prevents relative rotation between the drive case 21 and the internal rotor 22 while allowing the internal rotor 22 to be displaced in a direction perpendicular to the rotation axis X with respect to the drive case 21. Has been.

  The eccentric cam body 28 is supported by the first bearing 31 with respect to the front plate 24 so as to rotate on the same axis as the rotation axis X. The eccentric cam body 28 is integrally formed with an eccentric cam surface 28A centering on an eccentric shaft core Y in a posture parallel to the rotation shaft core X, and an inner gear is connected to the eccentric cam surface 28A via a second bearing 32. 27 is rotatably supported. In addition, a spring body 29 is fitted into a recess formed in the eccentric cam surface 28 </ b> A, and the urging force of the spring body 29 is applied to the inner gear 27 via the second bearing 32.

  The eccentric cam body 28 has a cylindrical shape as a whole, and a pair of engagement grooves 28B are formed on the inner periphery in a posture parallel to the rotation axis X.

  Thereby, a part of the outer tooth portion 27T of the inner gear 27 is engaged with a part of the inner tooth portion 26T of the ring gear 26. In addition, although the 1st bearing 31 and the 2nd bearing 32 are comprised with a ball bearing, you may comprise with a bush.

  The joint portion J has a joint member 33 formed by pressing a plate material, and a pair of engagement arms 33A formed on the joint member 33 is engaged with the engagement groove portion 21G of the drive case 21, so that the joint The pair of engaging recesses 33 </ b> B formed in the member 33 are configured to engage with the engaging protrusions 27 </ b> U of the inner gear 27.

  That is, the joint member 33 has a central portion formed in an annular shape, and a pair of engaging arms 33A projecting outward from the annular central portion, and is connected to a space in the annular central portion. The engaging recess 33B is formed.

  In the joint portion J, the joint member 33 is freely displaceable in a linear direction connecting the pair of engagement groove portions 21G of the drive case 21, and the inner gear 27 connects the pair of engagement protrusions 27U to the joint member 33. Displaceable in the direction.

  The phase control motor M is supported by the engine E and includes an engagement pin 34 provided in a posture orthogonal to the output shaft Ma. The engagement pin 34 is connected to the inner periphery of the eccentric cam body 28. It fits in the joint groove 28B. As the phase control motor M, a brushless DC motor is used, but a synchronous motor such as a stepping motor may be used.

  As a result, when the operation mode is considered with the engine E stopped, when the eccentric cam body 28 is rotated by the driving force of the phase control motor M, the eccentric cam surface 28A rotates about the rotation axis X, With this rotation, the inner gear 27 starts to revolve around the rotation axis X. During this revolution, the engagement position between the outer tooth portion 27T of the inner gear 27 and the inner tooth portion 26T of the ring gear 26 is displaced along the inner periphery of the ring gear 26, so that the inner gear 27 has a force to rotate around the eccentric shaft core Y. Works.

  That is, when the inner gear 27 revolves only once, an angle (one tooth) corresponding to the difference between the number of teeth of the inner tooth portion 26T of the ring gear 26 and the number of teeth of the outer tooth portion 27T of the inner gear 27 (tooth number difference). Rotational force (rotational force) is applied to rotate the inner gear 27 by an angle corresponding to the angle.

  As described above, since the joint portion J has a structure that restricts the rotation of the inner gear 27 with respect to the drive case 21, the inner gear 27 does not rotate with respect to the drive case 21, and the rotational force acting on the inner gear 27 The ring gear 26 rotates with respect to the drive case 21, and the internal rotor 22 rotates relative to the ring gear 26, so that the rotation phase of the intake camshaft 7 relative to the drive case 21 is adjusted.

  In particular, when the inner gear 27 revolves only one rotation around the rotation axis X, the intake camshaft 7 is different from the drive case 21 in the number of teeth of the outer teeth 27T of the inner gear 27 (the number of teeth difference). ), It can be adjusted with a large reduction ratio.

[Valve opening / closing timing control mechanism: Overview of phase adjustment]
When adjusting the phase of the valve opening / closing timing control mechanism VT, the phase control unit 43 of the engine control device 40 drives the output shaft Ma of the phase control motor M in the same direction as the rotational speed of the intake camshaft 7. By rotating, the relative rotation phase between the drive case 21 and the internal rotor 22 is maintained.

  Further, the relative rotational phase is displaced in the advance direction Sa or the retard direction Sb by increasing or decreasing the rotational speed of the phase control motor M with reference to the rotational speed of the intake camshaft 7. The displacement direction of the relative rotational phase with respect to the increase or decrease of the rotational speed of the phase control motor M (either the advance angle direction Sa or the retard angle direction Sb) is determined by the gear configuration of the phase adjustment unit.

  In particular, since the valve opening / closing timing control mechanism VT displaces the relative rotational phase by the driving force of the phase control motor M, the valve opening / closing timing control mechanism VT can operate at a higher speed than the one that realizes the displacement by hydraulic pressure. Even in a situation where the hydraulic pressure is not sufficient as in the case of time, it is possible to quickly set the required rotation phase.

(Control configuration)
As shown in FIG. 2, the engine control device 40 receives detection signals from the crank sensor portion 16S of the crank sensor 16 and the intake cam sensor portion 17S of the intake cam angle sensor 17, and also includes a phase control motor M, a starter A control signal is output to the motor 15, and further, a control signal is output to the injector 9 and the spark plug 10.

  The basic concept of the control mode is to reduce the load during cranking by setting the opening / closing timing of the intake valve Va to the most retarded angle as shown in FIG. 7 when cranking is started by driving the starter motor 15. To do. Further, after the start of cranking, the opening / closing timing (opening / closing timing) of the intake valve Va is set to the most advanced angle until the ignition control unit 42 performs the first combustion in any of the plurality of combustion chambers as shown in FIG. By setting, when the first combustion is performed, the intake amount is increased, the compression temperature is raised, the startability is improved, and the emission amount of THC (unburned hydrocarbon) is suppressed. Four types of control based on this concept will be described below.

  In FIGS. 7 and 8, a region where the exhaust valve Vb is open and exhaust is performed is shown as an exhaust region Ex, and a region where the intake valve Va is open and intake is performed is shown as an intake region In. In the most retarded phase shown in FIG. 7, EVC that is the closing timing of the exhaust valve Vb (hereinafter simply referred to as “EVC”) is set slightly behind the top dead center TDC and becomes the opening timing of the intake valve Va. IVO (hereinafter, simply referred to as IVO) is set at a position that is larger than the top dead center TDC and separated from the retard side. In the figure, EVO is the opening timing of the exhaust valve Vb, and IVC is the closing timing of the intake valve.

  In the engine E, the EVC at which the exhaust valve Vb is closed is set (fixed) slightly on the retard side from the top dead center TDC. In the most advanced angle phase shown in FIG. 8, the overlap OL is created by displacing the IVO, which is the opening timing of the intake valve Va, from the top dead center TDC toward the advance side.

  In the following description, the cylinder that is first compressed in cranking is the # 1 cylinder, but it is not limited to the # 1 cylinder. Further, although the compression order of each cylinder (corresponding to the combustion order) is set to # 1, # 3, # 4, and # 2 cylinders, the order of compression is not limited to this. . The cylinder discriminating unit 44 can discriminate the stroke in each cylinder when the crankshaft 1 rotates about half to one rotation.

[First control form]
As shown in the flowchart of FIG. 9, when the engine control device 40 acquires a start signal for starting the engine E, the intake valve Va is retarded and the IVO of the intake valve Va is set to the most retarded phase (FIG. 7). (See step # 101).

  Prior to the start of cranking, the crankshaft 1 does not rotate and cannot be detected by the intake cam angle sensor 17. Accordingly, in order to set the opening / closing timing of the intake valve Va to the most retarded angle, the valve opening / closing timing control mechanism VT is operated by driving the phase control motor M until the limit of the most retarded phase is reached. This is an example of a control mode in which the valve opening / closing timing control mechanism VT is set to the most retarded phase, and the phase control motor M at the timing when the valve opening / closing timing control mechanism VT reaches the most retarded phase (mechanical operation limit). Therefore, the control for stopping the supply of current to the phase control motor M is performed when the supplied current value exceeds a preset threshold value.

  In this embodiment, instead of such a control mode, for example, it is conceivable to set the relative rotation phase of the valve opening / closing timing control mechanism VT to the most retarded angle in the control for stopping the engine E. By adopting such a control mode, if the valve opening / closing timing control mechanism VT is set to the most retarded angle when the engine E is stopped, the control in step # 101 is not required.

  It is also conceivable to store the relative rotation phase of the valve opening / closing timing control mechanism VT when the engine E stops in a nonvolatile memory or the like of the engine control device 40. Thus, in the case where the relative rotational phase is stored when the engine E is stopped, the control amount of the relative rotational phase can be set on the basis of the storage, and the control in step # 101 can be simplified.

  Next, the cranking is started by driving the starter motor 15, and the phase control motor M is started at a speed synchronized with the rotation of the starter motor 15 in order to maintain the valve opening / closing timing control mechanism VT at the most retarded angle phase. Then, the measurement of the elapsed time by the timer is started, and when the set time T has elapsed (time up), the opening / closing timing of the intake valve Va is set to the most advanced angle (see FIG. 8) by the advance angle control. Control is performed (steps # 102 to # 105). The timer is assumed to be configured as software in the engine control device 40.

  FIG. 10 shows changes in the current value supplied to the starter motor 15 when cranking is started. In FIG. 10, # 1, # 2, # 3, and # 4 indicate that these cylinders are compressed. The timing when the dead point TDC is reached is shown. As the set time T, the timing at which the # 3 cylinder reaches the compression top dead center TDC after the compression stroke in the # 1 cylinder is completed is set. Since the valve opening / closing timing control mechanism VT changes the relative rotational phase (opening / closing timing) by the operation of the phase control motor M, there is a time lag until the change from the most retarded phase to the most advanced angle phase is completed. Even when the control is started at the timing when the compression top dead center TDC of the # 3 cylinder is reached, when the relative rotational phase of the valve opening / closing timing control mechanism VT reaches the most advanced angle, the # 4 cylinder is approximately compressed at the top dead center. TDC.

  In FIG. 10, the change in current value when the opening / closing timing of the intake valve Va is set to the most retarded angle is shown by a solid line, and the current value when the opening / closing timing of the intake valve Va is maintained at the most advanced angle is shown. The change is indicated by a broken line. Further, the set time T is not fixed to a fixed value, and may be a value set based on the rotational speed of the crankshaft 1 at the time of cranking, for example.

  After the control for setting the relative rotational phase to the most advanced angle is performed as described above, after the discrimination by the cylinder discriminating unit 44, the ignition control unit 42 performs the first combustion at the timing C, followed by the predetermined combustion. The combustion is continuously performed in this order (steps # 106 and # 107). In FIG. 10, timing C is set so that the first combustion is performed in the # 1 cylinder, but the cylinder performing the first combustion is not limited to the # 1 cylinder.

  Therefore, in the first control mode, the valve opening / closing timing control mechanism VT of the intake valve Va is set to the most retarded phase to start cranking, and the relative rotation phase is set at the timing when the set time T has elapsed from the start of cranking. Control to shift to the most advanced angle is started. As a result, the load acting on the starter motor 15 is reduced at the start of cranking, the power consumption (current value) is reduced, and the number of revolutions of the crankshaft 1 (the number of revolutions per unit time) can be increased. . Thereafter, by setting the valve timing control mechanism VT to the most advanced angle phase, at the time of the first combustion, not only the intake air amount is increased and the compression temperature is increased, but also the combustion that suppresses the increase in THC is suppressed. to enable.

[Second Control Mode]
In the second control mode, as shown in the flowchart of FIG. 11, the steps # 201 and # 202 are the same as the steps # 101 and 102 in the flowchart described in the first control mode, and steps # 205 to # 207 are performed. Is the same control as steps # 105 to # 107 in the flowchart described in the first control mode.

  That is, when the engine control device 40 acquires a start signal for starting the engine E, the intake valve Va is retarded and the IVO of the intake valve Va is set to the most retarded phase as shown in FIG. Step # 201). In step # 201, the current supplied to the phase control motor M at the timing when the valve opening / closing timing control mechanism VT reaches the most retarded phase (mechanical operation limit), as in the first embodiment. The control etc. which stop is performed.

  Next, the cranking is started by driving the starter motor 15, and the phase control motor M is started at a speed synchronized with the rotation of the starter motor 15 in order to maintain the valve opening / closing timing control mechanism VT at the most retarded angle phase. Then, after the crank sensor 16 (an example of a crank angle sensor) detects that the crankshaft 1 has made a half rotation, control is performed to set the opening / closing timing of the intake valve Va to the most advanced angle by advance angle control (# 202). Step # 205.

  When the engine E stops, the rotation of the crankshaft 1 stops immediately before any cylinder reaches the compression top dead center TDC (usually about 80 degrees before the top dead center at the crank angle). The disc portion 16D of the crank sensor 16 shown in FIG.

  Therefore, as shown in FIG. 12, in the situation where the # 1 cylinder is first compressed in cranking, if the crank angle in the situation where the # 1 cylinder is at the top dead center TDC is set to 0 degrees, the crankshaft 1 is 180 degrees. In the case of rotation by the degree, the # 3 cylinder is at the compression top dead center TDC. In this control, the control is performed so that the opening / closing timing of the intake valve Va is set to the most advanced timing at the timing when the crankshaft 1 is rotated 1/2 (180 degrees) with respect to the time when the engine E is stopped. Shortly before the compression top dead center TDC is reached, control is performed to switch the opening / closing timing of the intake valve Va from the most retarded angle to the most advanced angle. As a result, the control for switching the opening / closing timing of the intake valve Va can be started until the compression stroke of the # 1 cylinder is substantially completed.

  In this control, the crank sensor 16S of the crank sensor 16 having the configuration shown in FIG. 2 counts the tooth portion 16T of the disk portion 16D, thereby detecting that the crankshaft 1 has made a half rotation from the start of cranking. To do. Further, instead of this control mode, for example, the positional relationship is set so that the crank sensor unit 16S detects the reference point 16n of the disk unit 16D where the engine E stops, and the crankshaft 1 is 180 degrees in cranking. The timing at which the reference point 16n is rotated may be set so as to be determined as 1/2 rotation of the crankshaft 1.

  Since the valve opening / closing timing control mechanism VT changes the relative rotational phase (opening / closing timing) by the operation of the phase control motor M, there is a time lag until the change from the most retarded phase to the most advanced angle phase is completed. As shown in FIG. 12, even when the control is started at the timing before reaching the compression top dead center TDC in the # 3 cylinder, when the relative rotational phase of the valve opening / closing timing control mechanism VT reaches the most advanced angle, The # 4 cylinder has a timing slightly before the compression top dead center TDC.

  After the control for setting the relative rotational phase to the most advanced angle is performed as described above, after the discrimination by the cylinder discriminating unit 44, the ignition control unit 42 performs the first combustion at the timing C, followed by the predetermined combustion. In this order, combustion is continuously performed (steps # 206 and # 207). In FIG. 12, the timing C is set so that the first combustion is performed in the # 1 cylinder, but the cylinder performing the first combustion is not limited to the # 1 cylinder.

  Therefore, in the second control mode, cranking is started by setting the valve opening / closing timing control mechanism VT of the intake valve Va to the most retarded angle phase, and relative to the timing at which the crankshaft 1 has rotated 1/2 turn from the start of cranking. Control for shifting the rotational phase to the most advanced angle is started. As a result, the load acting on the starter motor 15 is reduced at the start of cranking, the power consumption (current value) is reduced, and the number of revolutions of the crankshaft 1 (the number of revolutions per unit time) can be increased. . Thereafter, by setting the valve timing control mechanism VT to the most advanced angle phase, at the time of the first combustion, not only the intake air amount is increased and the compression temperature is increased, but also the combustion that suppresses the increase in THC is suppressed. to enable.

[Third control mode]
In the third control mode, as shown in the flowchart of FIG. 13, steps # 301 and # 302 are the same control as steps # 101 and 102 in the flowchart described in the first control mode, and # 305 to # 307. The steps are the control common to the steps # 105 to # 107 in the flowchart described in the first control mode.

  That is, when the engine control device 40 acquires a start signal for starting the engine E, the intake valve Va is retarded and the IVO of the intake valve Va is set to the most retarded phase as shown in FIG. Step # 301). In step # 301, the current supplied to the phase control motor M at the timing when the valve opening / closing timing control mechanism VT reaches the most retarded phase (mechanical operating limit), as in the first embodiment. The control etc. which stop is performed.

  Next, the cranking is started by driving the starter motor 15, and the phase control motor M is started at a speed synchronized with the rotation of the starter motor 15 in order to maintain the valve opening / closing timing control mechanism VT at the most retarded angle phase. When the rotation angle of the intake camshaft 7 is acquired based on the detection signal of the intake cam angle sensor 17 and it is determined that one of the cylinders shifts to the compression stroke, the opening / closing timing of the intake valve Va is controlled by the advance angle control. Is set to the most advanced angle (steps # 302 to # 305).

  As shown in FIG. 2, the intake cam angle sensor 17 forms four detection areas 17T by dividing the rotating body 17D into four in the circumferential direction. If the crankshaft 1 rotates halfway, the four detection areas 17T are formed. One of 17T is detected, and this detection makes it possible to determine which of the four cylinders is in the compression stroke.

  Further, when the intake cam sensor unit 17S detects any one of the four detection areas 17T, it is also possible to detect the angle of the intake camshaft 7 from the count value of the clock signal. That is, when the crankshaft 1 rotates at a predetermined rotational speed, the predetermined cylinder is compressed when the intake cam sensor unit 17S reaches a predetermined count value based on the timing at which the above-described up edge is detected. It is also possible to determine that the dead point TDC has been reached. Since the valve opening / closing timing control mechanism VT is set to the most retarded phase at the time of starting cranking, this relative rotational phase is taken into account when determining that the compression top dead center TDC has been reached. It is necessary to perform processing. By using this principle, it is determined that any cylinder is in the compression stroke based on the count value of the intake cam sensor unit 17S.

  Since the valve opening / closing timing control mechanism VT changes the relative rotational phase (opening / closing timing) by the operation of the phase control motor M, there is a time lag until the change from the most retarded phase to the most advanced angle phase is completed. Even when the control is started at the timing when the compression top dead center TDC of the # 3 cylinder is reached, when the relative rotational phase of the valve opening / closing timing control mechanism VT reaches the most advanced angle, the # 4 cylinder is approximately compressed at the top dead center. TDC.

  After the control for setting the relative rotational phase to the most advanced angle is performed as described above, after the discrimination by the cylinder discriminating unit 44, the ignition control unit 42 performs the first combustion at the timing C, followed by the predetermined combustion. In this order, combustion is continuously performed (steps # 306 and # 307).

  Therefore, in the third control mode, the valve opening / closing timing control mechanism VT of the intake valve Va is set to the most retarded angle phase and cranking is started. After the cranking is started, the intake cam angle sensor for cylinder discrimination is started. Based on the detection of 17, the control to shift the relative rotational phase of the intake valve Va to the most advanced angle is started. As a result, the load acting on the starter motor 15 is reduced at the start of cranking, the power consumption (current value) is reduced, and the number of revolutions of the crankshaft 1 (the number of revolutions per unit time) can be increased. . Thereafter, by setting the valve timing control mechanism VT to the most advanced angle phase, at the time of the first combustion, not only the intake air amount is increased and the compression temperature is increased, but also the combustion that suppresses the increase in THC is suppressed. to enable.

  The basic concept of the third embodiment is that the relative rotational phase of the valve opening / closing timing control mechanism VT is set to the most retarded angle by using at least one of the crank sensor 16 used for cylinder discrimination and the intake cam angle sensor 17. The timing for shifting from the phase to the most advanced angle phase is set. Accordingly, the control mode may be set so that the detection signal of the crank sensor 16 is acquired at the time of cranking, and the transition to the most advanced angle phase is performed based on this detection signal.

[Fourth control mode]
In the fourth control mode, as shown in the flowchart of FIG. 14, steps # 401 and # 402 are the same control as steps # 101 and 102 in the flowchart described in the first control mode, and # 406 to # 408. The steps are the control common to the steps # 105 to # 107 in the flowchart described in the first control mode.

  That is, when the engine control device 40 acquires a signal for starting the engine E, the intake valve Va is retarded and the IVO of the intake valve Va is set to the most retarded phase as shown in FIG. Step # 401). In step # 401, the current supplied to the phase control motor M at the timing when the valve opening / closing timing control mechanism VT reaches the most retarded angle phase (mechanical operation limit), as in the first embodiment. The control etc. which stop is performed.

  Next, the cranking is started by driving the starter motor 15, and the phase control motor M is started at a speed synchronized with the rotation of the starter motor 15 in order to maintain the valve opening / closing timing control mechanism VT at the most retarded angle phase. The crank sensor 16 obtains the angular velocity ω of the crankshaft 1. As a result of this acquisition, as shown in FIG. 15, when it is detected that the angular velocity ω has passed the first peak P1 on the lowering side and the first peak P2 on the rising side (second peak P2), Control is performed to set the opening / closing timing of the intake valve Va to the most advanced angle by advance angle control (steps # 402 to # 406).

  Specifically, the crank sensor 16 and software set in the engine control device 40 constitute a speed sensor that acquires the angular speed ω based on the detection of the crank sensor 16. The upper end of FIG. 15 shows a change in the current value supplied to the starter motor 15 when cranking is started, and the lower part of FIG. 15 shows the angular velocity of the crankshaft 1. Therefore, as shown in FIG. 15, at the first peak P1 corresponding to the compression top dead center TDC in the # 1 cylinder, the angular velocity ω decreases most, and then the angular velocity ω increases, and the compression in the # 3 cylinder is started. At the second peak P2 at which the angular velocity decreases most immediately before starting, control is performed to change the opening / closing timing of the intake valve Va toward the most advanced angle.

  Since the valve opening / closing timing control mechanism VT changes the relative rotational phase (opening / closing timing) by the operation of the phase control motor M, there is a time lag until the change from the most retarded phase to the most advanced angle phase is completed. Even when the control is started at the timing when the compression top dead center TDC of the # 3 cylinder is reached, when the relative rotational phase of the valve opening / closing timing control mechanism VT reaches the most advanced angle, the # 4 cylinder is approximately compressed at the top dead center. TDC.

  After the control for setting the relative rotational phase to the most advanced angle is performed as described above, after the discrimination by the cylinder discriminating unit 44, the ignition control unit 42 performs the first combustion at the timing C, followed by the predetermined combustion. In this order, combustion is continuously performed (steps # 407 and # 408). In FIG. 15, the timing C is set so that the first combustion is performed in the # 1 cylinder, but the cylinder performing the first combustion is not limited to the # 1 cylinder.

  Therefore, in the fourth control mode, the valve opening / closing timing control mechanism VT of the intake valve Va is set to the most retarded angle phase to start cranking, and the angular velocity ω of the crankshaft 1 is obtained from the start of cranking. Control is performed to set the relative rotation phase to the most advanced angle at the timing when the angular velocity ω rises most. As a result, the load acting on the starter motor 15 is reduced at the start of cranking, the power consumption (current value) is reduced, and the number of revolutions of the crankshaft 1 (the number of revolutions per unit time) can be increased. . Thereafter, by setting the valve timing control mechanism VT to the most advanced angle phase, at the time of the first combustion, not only the intake air amount is increased and the compression temperature is increased, but also the combustion that suppresses the increase in THC is suppressed. to enable.

[Effects of Embodiment]
At the start of cranking by driving the starter motor 15, the start control unit 41 (start load reducing unit) reduces the load acting on the starter motor 15 by setting the opening / closing timing of the intake valve Va to the most retarded angle. By reducing the electric power, cranking is surely performed even when starting in a cryogenic environment, and the number of rotations (rotational speed) of the crankshaft 1 is preferentially increased. Further, the start control unit 41 (start load reducing unit) sets the opening / closing timing of the intake valve Va to the most advanced angle by the advance angle control until the first combustion is performed in the combustion chamber after the crankshaft 1 is reliably rotated. By setting, the intake air amount is increased at the time when the first combustion is performed, and the compression temperature is increased to enable the combustion in which the increase in THC is suppressed.

  Further, since the valve opening / closing timing control mechanism VT sets the opening / closing timing by the driving force of the electric actuator, for example, compared with the valve opening / closing timing setting by hydraulic oil supplied from a hydraulic pump driven by the engine E. Thus, the engine E operates at high speed even when the engine E is started, and sets the opening / closing timing appropriately. As a result, the engine control device 40 that reduces the load at the time of start and enables a good start while reducing THC is configured.

  In particular, in this configuration, an electric valve opening / closing timing control mechanism VT for setting the opening / closing timing of the intake valve Va of the engine E is required. It is possible to execute control in any of the forms (first to fourth control forms), and in any control form, the load acting on the starter motor 15 at the time of cranking is reduced, and a good start Enable.

[Another embodiment]
In addition to the above-described embodiments, the present invention may be configured as follows (the components having the same functions as those of the embodiments are given the same numbers and symbols as those of the embodiments).

(A) The start control unit 41 (after the determination by the cylinder determination unit 44 is performed as the timing for changing the relative rotation phase of the valve opening / closing timing control mechanism VT from the most retarded phase to the most advanced angle phase. The control mode of the starting load reduction unit is set. Thus, even if the control mode is set, the engine E (internal combustion engine) can be started well.

(B) In the embodiment, the mechanical limit position in the retardation direction Sb in the valve opening / closing timing control mechanism VT is the most retarded angle phase, but the most retarded angle phase is not necessarily the mechanical limit position. The phase may be close to the mechanical limit.

(C) In order to set the opening / closing timing of the exhaust valve Vb, the exhaust valve Vb is provided with a valve opening / closing timing control mechanism VT having the same configuration as that provided for the intake valve Va. Thus, by providing the intake valve Va and the exhaust valve Vb with the valve opening / closing timing control mechanism VT, the amount of negative overlap is increased at the start of cranking, and the load can be further reduced. Thereafter, when the overlap OL is set, the amount of intake can be further increased by increasing the lap amount.

  The present invention can be used for a control device for starting an internal combustion engine.

1 Crankshaft 7 Intake Camshaft 8 Exhaust Camshaft 15 Starter Motor 16 Crank Sensor (Crank Angle Sensor)
17 Intake cam angle sensor (cam angle sensor)
42 Ignition control unit 43 Start load reducing unit E Internal combustion engine M Phase control motor (electric actuator)
T Set time VT Valve opening / closing timing control mechanism Va Intake valve

Claims (5)

An intake valve that opens and closes the combustion chamber in conjunction with rotation of the crankshaft, a starter motor that drives and rotates the crankshaft, an ignition control unit that ignites an air-fuel mixture in the combustion chamber, and the intake valve that is driven by an electric actuator An internal combustion engine comprising a valve opening / closing timing control mechanism for setting the opening / closing timing of
At the start of cranking by driving the starter motor, the opening / closing timing of the intake valve is set to the most retarded angle. After the cranking is started, the ignition control unit performs the first combustion in any of the plurality of combustion chambers. A control device for an internal combustion engine, comprising: a starting load reduction unit that controls the electric actuator of the valve opening / closing timing control mechanism so that the opening / closing timing of the intake valve is displaced to an advance side before the operation is performed.   The start load reducing unit sets the opening / closing timing of the intake valve to the most retarded angle until a set time elapses from the start of cranking, and advances the opening / closing timing of the intake valve after the set time elapses. The control device for an internal combustion engine according to claim 1, wherein the control is performed so that the advance angle is displaced to the side. The internal combustion engine has four or more cylinders, and a crank angle sensor that detects an angle of the crankshaft to perform cylinder discrimination, and a cam angle sensor that detects an angle of an intake camshaft or an exhaust camshaft. Has
The start load reducing unit sets the opening / closing timing of the intake valve to the most retarded angle until it detects that the crankshaft has made a half rotation from the start of cranking based on the detection result of the crank angle sensor. 2. The control device for an internal combustion engine according to claim 1, wherein after the detection, an advance angle control for displacing the intake valve to an advance angle side is performed. The internal combustion engine includes a crank angle sensor that detects an angle of the crankshaft to perform cylinder discrimination, and a cam angle sensor that detects an angle of an intake camshaft or an exhaust camshaft,
The starting load reduction unit is configured to perform the intake until it detects that one of a plurality of cylinders has reached compression top dead center based on the detection result of at least one of the crank angle sensor and the cam angle sensor. 2. The control device for an internal combustion engine according to claim 1, wherein the valve opening / closing timing is set to the most retarded angle, and after this detection, the advance angle control for displacing the intake valve to the advance angle side is performed. The internal combustion engine includes a speed sensor capable of detecting a change in angular speed when the crankshaft rotates;
The start load reducing unit keeps opening and closing timing of the intake valve until it detects that the angular velocity has increased after the angular velocity has been lowered by the speed sensor after the cranking has started, and that the angular velocity has reached the rising peak. 2. The control device for an internal combustion engine according to claim 1, wherein an advance angle control is performed in which the most retarded angle is set, and after the detection, the intake valve is displaced to the advance angle side.

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