JP2011252422A - Start control system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly make a phase of a camshaft advance to a reference phase, when a two-cylinder internal combustion engine starts, wherein the internal combustion engine includes: a variable valve system for varying the phase of the camshaft relative to a crankshaft; and a lock mechanism for fixing the phase of the camshaft to the reference phase which is the phase adapted to a start of the internal combustion engine.SOLUTION: The system includes: an advancing mechanism for using torque which acts on from a valve spring to the camshaft during a valve-closing-operation period of a valve to make the phase of the camshaft advance to the reference phase, while the internal combustion engine is cranking; and a control unit for reducing generated torque of a starter motor when a rotational position of the camshaft belongs in the valve-closing-operation period, compared with not belonging in the valve-closing-operation period, while the advancing mechanism makes the phase of the camshaft advance.

Description

  The present invention relates to an internal combustion engine start control system, and more particularly to an internal combustion engine start control system having two cylinders.

  As an internal combustion engine mounted on a vehicle or the like, there is an internal combustion engine having a variable valve mechanism that changes the opening / closing timing (phase) of a valve (intake valve or exhaust valve) by changing the phase of a camshaft with respect to a crankshaft. Are known.

  In the internal combustion engine as described above, the reaction force of the valve spring acts to retard the camshaft phase. Therefore, if the variable valve mechanism is a mechanism that uses hydraulic pressure to advance and retard the camshaft phase, the camshaft phase can be most retarded when the internal combustion engine is started. There is sex.

  On the other hand, the camshaft phase is changed to a predetermined intermediate phase using the torque when the cam crest gets over the tappet and the torque when the cam crest gets over the tappet, and the camshaft phase is changed to the predetermined intermediate phase. A technique of locking with a phase has been proposed (see, for example, Patent Document 1).

JP 2009-68500 A JP 2004-324421 A

  By the way, when the above-described conventional technique is applied to a two-cylinder internal combustion engine, there is a possibility that the time required from the start of cranking to the locking of the camshaft phase may be long. In that case, since the cranking time becomes long, there is a possibility that problems such as an increase in power consumption of the starter motor may occur. Further, in a vehicle in which the operation of the internal combustion engine is automatically stopped and restarted, there is a possibility that the vehicle cannot be started quickly.

  The present invention has been made in view of the above-described problems. An object of the present invention is to provide a variable valve mechanism that changes the phase of the camshaft and a lock mechanism that locks the phase of the camshaft at a desired phase. When the two-cylinder internal combustion engine provided is started, the phase of the camshaft is quickly locked at a desired phase.

The present invention employs the following means in order to solve the above-described problems. That is, the present invention provides a variable valve mechanism that changes the phase of the camshaft relative to the crankshaft;
A lock mechanism that fixes the phase of the camshaft to a reference phase that is a phase suitable for starting an internal combustion engine;
A power generator for generating torque for cranking the internal combustion engine;
A start control system for a two-cylinder internal combustion engine equipped with
When cranking is started in a state where the camshaft is retarded from the reference phase, the camshaft phase is utilized using the torque acting from the valve spring to the camshaft during the valve closing operation period. An advance mechanism that advances the angle to the reference phase;
In the case where the advance mechanism advances the phase of the camshaft, when the rotational position of the camshaft belongs to the valve closing operation period, it does not belong to the valve closing operation period. And a controller for reducing the generated torque.

  The "valve closing period" here is the period from when the valve starts to lift until it finishes lifting (that is, the period from when the valve starts to open until it closes) until the valve finishes lifting from the maximum lift state Indicates the period. Hereinafter, a period from when the valve starts to lift until it reaches the maximum lift state is referred to as a “valve opening operation period”.

  During the valve closing operation period, a torque is applied to the camshaft from the valve spring to advance the phase of the camshaft. The amount of advance at that time is greater when the crankshaft rotational speed (engine rotational speed) is lower than when it is high.

  Here, when the internal combustion engine is a four-stroke cycle engine having four cylinders, a part of the valve closing operation period of one cylinder overlaps with the valve opening operation period of other cylinders. Therefore, the engine rotational speed during the valve closing operation period of one cylinder is reduced by the reaction force generated by the valve springs of the other cylinders.

  On the other hand, when the internal combustion engine is a four-stroke cycle engine having two cylinders, the valve closing operation period of one cylinder and the valve opening operation periods of other cylinders do not overlap. Therefore, the engine rotation speed during the valve closing operation period of one cylinder is not decelerated by the reaction force generated by the valve springs of the other cylinders. Therefore, the engine rotation speed during the valve closing operation period of the two-cylinder internal combustion engine is faster than the engine rotation speed during the valve closing operation period of the four-cylinder internal combustion engine. Thus, when the engine rotation speed during the valve closing operation period increases, the advance amount of the camshaft decreases.

  When the internal combustion engine is a four-cylinder four-stroke cycle engine, the valve closing operation period occurs twice per one rotation of the crankshaft. On the other hand, when the internal combustion engine is a two-cylinder four-stroke cycle engine, the valve closing operation period occurs once per one rotation of the crankshaft. Therefore, the frequency at which the phase of the camshaft is advanced in the 2-cylinder internal combustion engine is less than the frequency at which the phase of the camshaft is advanced in the 4-cylinder internal combustion engine.

  Therefore, the amount by which the phase of the camshaft is advanced per unit time (for example, per revolution of the crankshaft) is smaller in a 2-cylinder internal combustion engine than in a 4-cylinder internal combustion engine. As a result, in a 2-cylinder internal combustion engine, there is a possibility that the phase of the camshaft cannot be quickly changed to the reference phase.

  In view of this, the internal combustion engine start control system according to the present invention reduces the torque generated by the power generator when the rotational position of the camshaft is in the valve closing operation period. As a result, the engine rotation speed during the valve closing operation period decreases. When the engine speed during the valve closing operation period decreases, the advance amount of the camshaft increases during the valve closing operation period. As a result, the phase of the camshaft quickly reaches the reference phase.

  Therefore, according to the start control system for an internal combustion engine according to the present invention, it is possible to quickly lock the phase of the camshaft with the reference phase when starting the 2-cylinder internal combustion engine.

Note that the rotational position of the crankshaft and the rotational position of the camshaft are not synchronized until the phase of the camshaft is locked at the reference phase. Therefore, when the rotational position of the camshaft is calculated from the detection value of the crank position sensor or the like, there is a possibility that a deviation occurs between the calculated value and the actual rotational position. Further, since the phase of the camshaft is not stable until the phase of the camshaft is locked at the reference phase, there is a possibility that a deviation occurs between the detected value of the cam position sensor and the actual rotational position.

  If the timing for reducing the torque generated by the power generation device (hereinafter referred to as “torque reduction timing”) is determined based on the detection value of the sensor when the above-described deviation occurs, the valve closing operation is performed. There is also a difference between the period and the torque reduction timing. As a result, the amount of advance of the camshaft during the valve closing operation period is reduced.

  On the other hand, the control unit of the present invention may correct the detection value of the sensor using the timing at which the engine rotation speed fluctuates as a parameter, and determine the torque reduction timing according to the corrected detection value. Here, the “sensor” is a sensor that detects a physical quantity that correlates with the rotational position of the camshaft, such as a crank position sensor or a cam position sensor.

  When the torque reduction timing of the power generation device is determined by such a method, the difference between the timing at which the actual rotation position of the camshaft belongs to the valve closing operation period and the timing at which the generated torque of the power generation device is reduced is determined. It can be reduced or eliminated. As a result, a decrease in the advance amount due to the timing shift is suppressed or alleviated.

  According to the present invention, when a two-cylinder internal combustion engine having a variable valve mechanism that changes the phase of the camshaft and a lock mechanism that locks the phase of the camshaft at a desired phase is started, The phase can be quickly locked at the desired phase.

1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. It is a figure which shows schematic structure of a variable valve mechanism. It is a figure which shows the structure of a housing member and a vane rotor. It is a figure which shows the structure of a locking mechanism. It is a figure which shows the operating state of a locking mechanism. It is a figure which shows the structure of a ratchet mechanism. It is a figure which shows the non-operation state of a ratchet mechanism. It is a figure which shows the relationship between the lift amount of an intake valve, and the reaction force of a valve spring. It is a timing chart which shows the execution procedure of torque reduction control. It is a flowchart which shows the control routine performed when torque reduction control is implemented.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. An internal combustion engine 100 shown in FIG. 1 is a 4-stroke cycle spark ignition internal combustion engine (gasoline engine) having two cylinders. In FIG. 1, only one of the two cylinders is shown.

A piston 102 is slidably loaded in each cylinder 101 of the internal combustion engine 100 in the axial direction. Each cylinder 101 communicates with an intake port 103 for introducing fresh air (air) into the cylinder 101 and an exhaust port 104 for discharging gas in the cylinder 101. The internal combustion engine 100 includes an intake valve 105 for opening and closing the opening end of the intake port 103 facing the cylinder 101, and an exhaust valve 106 for opening and closing the opening end of the exhaust port 104 facing the cylinder 101. .

  The intake valve 105 and the exhaust valve 106 are urged in the valve closing direction by valve springs 105a and 106a, respectively. An intake camshaft 1 and an exhaust camshaft 30 are rotatably attached to the internal combustion engine 100. The intake camshaft 1 and the exhaust camshaft 30 are rotationally driven by the rotational force of a crankshaft (not shown). The intake camshaft 1 and the exhaust camshaft 30 are provided with cams, and when these cams rotate, the intake valve 105 and the exhaust valve 106 are driven in the valve opening direction.

  A fuel injection valve 107 that injects fuel into the intake port 103 of each cylinder 101 is attached to the internal combustion engine 100. The fuel injected from the fuel injection valve 107 is introduced into the cylinder 101 while being mixed with fresh air (air) in the intake port 103 when the intake valve 105 is opened. The air-fuel mixture introduced into the cylinder 101 is burned using the spark generated by the spark plug 108 as a spark. The gas burned in the cylinder 101 (burned gas) is discharged to the exhaust port 104 when the exhaust valve 106 is opened, and then discharged to the atmosphere from the exhaust port 104 via an exhaust manifold or an exhaust pipe (not shown). Is done.

  The internal combustion engine 100 also includes a variable valve mechanism 2 that changes the phase of the intake camshaft 1 with respect to the crankshaft. Hereinafter, the configuration of the variable valve mechanism 2 will be described with reference to FIGS.

  A vane rotor 21 is fastened to one end of the intake camshaft 1 by a bolt 22 so that the intake camshaft 1 and the vane rotor 21 rotate integrally. Four blade bodies (vanes) 21 a are radially formed on the outer periphery of the vane rotor 21.

  A cylindrical housing member 23 that accommodates the vane rotor 21 is provided on the outer periphery of the vane rotor 21. The housing member 23 is attached so as to be rotatable relative to the intake camshaft 1. A sprocket 24 is integrally formed on the outer periphery of the housing member 23. The sprocket 24 is connected to a sprocket attached to one end of the crankshaft via a timing chain. Thereby, the rotational force of the crankshaft is transmitted to the sprocket 24 and the housing member 23 via the timing chain, and the housing member 23 rotates synchronously with the crankshaft.

  On the inner periphery of the housing member 23, the same number (four in this figure) of convex portions 23a as the vanes 21a of the vane rotor 21 are formed, and the vanes 21a are accommodated in a space formed between the adjacent convex portions 23a. ing. The tip of the vane 21 a is in sliding contact with the inner periphery of the housing member 23, and the tip of the convex portion 23 a of the housing member 23 is in sliding contact with the outer periphery of the vane rotor 21. Further, the space between the adjacent convex portions 23a is divided into two spaces 25 and 26 by the vane 21a. Below, of these two spaces 25, 26, the space 25 on the side of the rotation direction of the intake camshaft 1 (in the direction of arrow α in FIG. 3) with respect to the vane 21a is the retarded hydraulic chamber, and the space 26 on the opposite side thereof. Is referred to as an advance hydraulic chamber.

The retarded hydraulic chamber 25 and the advanced hydraulic chamber 26 are increased or reduced in pressure by supply and discharge (supply / discharge) of hydraulic oil. When the hydraulic pressure in the retard hydraulic chamber 25 and the advanced hydraulic chamber 26 is changed and the balance of the forces acting on both sides of the vane 21 a is changed, the vane rotor 21 rotates relative to the housing member 23.

  For example, when hydraulic oil is supplied to the retard hydraulic chamber 25 and hydraulic oil in the advance hydraulic chamber 26 is discharged, the retard hydraulic chamber 25 increases in pressure and the advance hydraulic chamber 26 decreases in pressure. In this case, since the force for rotating the vane rotor 21 in the direction opposite to the arrow α in FIG. 3 acts on the vane 21a, the vane rotor 21 rotates relative to the housing member 23 in the direction opposite to the arrow α. As a result, the intake camshaft 1 is retarded with respect to the crankshaft.

  On the other hand, when the hydraulic oil is supplied to the advance hydraulic chamber 26 and the hydraulic oil in the retard hydraulic chamber 25 is discharged, the advance hydraulic chamber 26 increases in pressure and the retard hydraulic chamber 25 decreases in pressure. In this case, since the force for rotating the vane rotor 21 in the same direction as the arrow α in FIG. 3 acts on the vane 21a, the vane rotor 21 rotates relative to the housing member 23 in the same direction as the arrow α. As a result, the intake camshaft 1 is advanced with respect to the crankshaft.

  Thus, when the intake camshaft 1 is advanced or retarded with respect to the crankshaft, the opening / closing timing of the intake valve 105 is advanced or retarded accordingly. When the vane 21a rotates in the direction of the arrow α in FIG. 3 and comes into contact with the convex portion 23a of the housing member 23, the phase of the intake camshaft 1 becomes the most advanced state (maximum advance angle phase). . Further, when the vane 21a rotates in the direction opposite to the arrow α in FIG. 3 and contacts the convex portion 23a of the housing member 23, the phase of the intake camshaft 1 is most retarded (most retarded phase). It becomes.

  The variable valve mechanism 2 configured as described above is provided with an oil control valve (OCV) 7 for supplying and discharging hydraulic oil to and from the retard hydraulic chamber 25 and the advance hydraulic chamber 26. Although the internal structure of the OCV 7 is not shown, the OCV 7 has a spool (valve element) that can reciprocate in the axial direction, a coil spring that urges the spool, and an urging direction of the coil spring by applying a voltage. Is a 5-port electromagnetically driven valve provided with an electromagnetic solenoid that attracts in the opposite direction.

  Each port of the OCV 7 communicates with each of the oil supply passage L1, the first drain oil passage L2a, the second drain oil passage L2b, the retard oil passage L3, and the advance oil passage L4. The oil supply passage L <b> 1 is a passage for supplying hydraulic oil discharged from the oil pump 9 to the OCV 7. The first drain oil passage L2a and the second drain oil passage L2b are passages for returning the working oil from the OCV 7 to the oil pan. The retarded oil passage L3 is a passage for allowing hydraulic oil to travel between the retarded hydraulic chamber 25 and the OCV 7 of the variable valve mechanism 2 described above. The advance oil passage L4 is a passage for allowing hydraulic oil to travel between the advance hydraulic chamber 26 and the OCV 7 of the variable valve mechanism 2 described above.

  The retard oil passage L3 is electrically connected to either the oil supply passage L1 or the second drain oil passage L2b according to the displacement of the spool of the OCV7. When the retard oil passage L3 and the oil supply passage L1 are connected, the hydraulic oil discharged from the oil pump 9 is supplied to the retard hydraulic chamber 25 via the oil feed passage L1 and the retard oil passage L3. On the other hand, when the retard oil passage L3 and the second drain oil passage L2b are conducted, the hydraulic oil in the retard hydraulic chamber 25 is transferred to the oil pan via the retard oil passage L3 and the second drain oil passage L2b. Discharged.

The advance oil passage L4 is electrically connected to either the oil supply passage L1 or the first drain oil passage L2a according to the displacement of the spool of the OCV7. When the advance oil passage L4 and the oil supply passage L1 are connected, the hydraulic oil discharged from the oil pump 9 is supplied to the advance hydraulic chamber 26 via the oil supply passage L1 and the advance oil passage L4. On the other hand, when the advance oil passage L4 and the first drain oil passage L2a are electrically connected, the hydraulic oil in the advance oil pressure chamber 26 passes to the oil pan through the advance oil passage L4 and the first drain oil passage L2a. Discharged.

  In the OCV 7, when the retard oil passage L3 and the oil supply passage L1 are conducted, the advance oil passage L4 and the first drain oil passage L2a are also conducted, and the retard oil passage L3 and the second drain oil passage L2b. Is configured so that the advance oil passage L4 and the oil supply passage L1 are also conducted. Therefore, when the retard oil passage L3 and the oil supply passage L1 are conducted, the advance oil passage L4 and the first drain oil passage L2a are conducted, so that hydraulic oil is supplied to the retard hydraulic chamber 25. The hydraulic oil in the advance hydraulic chamber 26 is discharged. As a result, the intake camshaft 1 is retarded with respect to the crankshaft. When the retard oil passage L3 and the second drain oil passage L2b are connected, the advance oil passage L4 and the oil supply passage L1 are connected, so that hydraulic oil is supplied to the advance hydraulic chamber 26. The hydraulic oil in the retarded hydraulic chamber 25 is discharged. As a result, the intake camshaft 1 is advanced with respect to the crankshaft.

  Further, the variable valve mechanism 2 in the present embodiment is provided with a lock mechanism 20 for fixing (locking) the phase of the intake camshaft 1 to a predetermined phase. The predetermined phase here is an intermediate phase between the most advanced angle phase and the most retarded angle phase, and is a phase at which the opening / closing timing of the intake valve 105 is a timing suitable for starting the internal combustion engine 100. Hereinafter, this phase is referred to as a reference phase.

  Here, the configuration of the lock mechanism 20 will be described with reference to FIGS. Of the four vanes 21a, a side surface (left side surface in FIGS. 4 and 5) of one vane 21a has a cylindrical storage hole 21b extending in the axial direction of the vane 21a (the axial direction of the vane rotor 21). Is provided. The storage hole 21b is formed such that a portion close to the side surface of the vane 21a has a smaller diameter than a portion far from the small portion, and the small diameter portion and the large diameter portion communicate with each other through a step.

  The above-described storage hole 21b stores a lock pin 20a that is slidable in the axial direction and a spring 20b that generates a biasing force that causes the lock pin 20a to protrude from the storage hole 21b. The lock pin 20a includes a cylindrical portion having an outer diameter substantially equal to the small diameter portion of the storage hole 21b, and a flange portion having an outer diameter substantially equal to the large diameter portion of the storage hole 21b.

  Further, in the housing member 23, a locking hole 23b into which the tip of the lock pin 20a is fitted is formed at a portion facing the storage hole 21b when the phase of the intake camshaft 1 matches the reference phase. .

  According to the lock mechanism 20 configured as described above, when the vane rotor 21 rotates relative to the housing member 23 and the position of the storage hole 21b coincides with the position of the locking hole 23b, the lock pin is moved by the biasing force of the spring 20b. 20a protrudes from the storage hole 21b, and the tip of the lock pin 20a is fitted into the locking hole 23b (see FIG. 5). By this fitting, the relative rotation of the vane rotor 21 with respect to the housing member 23 is restricted, and the phase of the intake camshaft 1 is fixed (locked) to the reference phase.

  In the storage hole 21b, an annular space 21c between the step and the flange portion of the lock pin 20a is a hydraulic chamber (hereinafter referred to as a hydraulic chamber) that generates hydraulic pressure for releasing the lock pin 20a from the locking hole 23b. , Referred to as “unlocked hydraulic chamber”). As shown in FIG. 2, the unlocking hydraulic chamber 21c communicates with the hydraulic oil switching valve (OSV) 8 via the unlocking oil passage L7.

The OSV 8 is a three-port valve that incorporates a spool that reciprocates by the cooperation of an electromagnetic solenoid and a coil spring, and that controls the displacement of the spool by duty-controlling the voltage applied to the electromagnetic solenoid. The aforementioned unlocking oil passage L7 is connected to one port of the OSV8. The remaining two ports in the OSV 8 are connected to a branch oil passage L5 branched from the oil supply passage L1 and a third drain oil passage L6 for returning the hydraulic oil to the oil pan.

  The unlocking oil passage L7 is electrically connected to either the branch oil passage L5 or the third drain oil passage L6 in accordance with the displacement of the spool of the OSV8. When the unlocking oil passage L7 is electrically connected to the branch oil passage L5, the hydraulic oil discharged from the oil pump 9 is unlocked via the oil supply passage L1, the branch oil passage L5, and the unlocking oil passage L7. It is supplied to the chamber 21c. In that case, the hydraulic pressure in the unlocking hydraulic chamber 21c increases. When the hydraulic pressure in the unlocking hydraulic chamber 21c becomes larger than the urging force of the spring 20b, the lock pin 20a is detached from the locking hole 23b and stored in the storage hole 21b (see FIG. 4). As a result, the connection state between the vane rotor 21 and the housing member 23 is released, and relative rotation between the vane rotor 21 and the housing member 23 is allowed.

  Next, the variable valve mechanism 2 is provided with a ratchet mechanism 27 that allows the housing member 23 to rotate the vane rotor 21 toward the advance side and restricts the rotation toward the retard side. For example, as shown in FIG. 6, the ratchet mechanism 27 includes a piece storage hole 21d provided on one side surface of the vane rotor 21, a piece 27a slidably inserted into the piece storage hole 21d, and a piece 27a. A spring 27b that urges in a direction protruding from the storage hole 21d, and a fitting groove 23c provided in the housing member 23 facing the piece storage hole 21d are provided.

  The piece storage hole 21d is a hole in which the small-diameter portion and the large-diameter portion are communicated with each other through a step, similarly to the storage hole 21b described above. The piece 27a includes a cylindrical part having an outer diameter substantially the same as the small diameter part of the piece storage hole 21d, and a flange part having an outer diameter substantially the same as the large diameter part. As shown in FIG. 3, the fitting grooves 23 c are arranged at a plurality of locations opposite to the arcuate locus on which the piece storage hole 21 d moves. Further, in the fitting groove 23c, the surface located on the retard side of the vane rotor 21 is formed as a steep slope, and the surface located on the advance side of the vane rotor 21 is formed as a gentle slope.

  According to the ratchet mechanism 27 configured as described above, when the vane rotor 21 rotates to the advance side and the position of the piece storage hole 21d matches the position of the fitting groove 23c, the piece 27a protrudes from the piece storage hole 21d, The tip of the piece 27a is fitted into the fitting groove 23c. Even if a force is generated to rotate the vane rotor 21 to the retard side when the tip of the piece 27a is fitted in the fitting groove 23c, the rotation of the vane rotor 21 to the retard side is restricted. . On the contrary, when a force is generated to rotate the vane rotor 21 to the advance side, the piece 27a is retracted along the gentle slope of the fitting groove 23c, so that the rotation of the vane rotor 21 to the advance side is performed. Permissible.

  In the above-described piece storage hole 21d, an annular space 21e between the above-described step and the flange portion of the piece 27a has a hydraulic chamber (hereinafter referred to as a hydraulic chamber) that generates hydraulic pressure for accommodating the piece 27a in the piece storage hole 21d. , Referred to as “ratchet release hydraulic chamber”). As shown in FIG. 2, the ratchet release hydraulic chamber 21e communicates with the lock release oil passage L7 via the ratchet release oil passage L8. Therefore, when the unlocking oil passage L7 and the branch oil passage L5 are made conductive by the OSV 8, the hydraulic oil discharged from the oil pump 9 is supplied to the ratchet releasing hydraulic chamber 21e in addition to the unlocking hydraulic chamber 21c. It will be.

  When hydraulic oil is supplied to the ratchet release hydraulic chamber 21e, the hydraulic pressure in the ratchet release hydraulic chamber 21e moves the piece 27a back into the piece storage hole 21d against the urging force of the spring 27b (see FIG. 7). As a result, the vane rotor 21 is allowed to rotate toward the retard side.

  The internal combustion engine 100 configured as described above is provided with an ECU 40. The ECU 40 is an electronic control unit that includes a CPU, a ROM, a RAM, a backup RAM, and the like. The ECU 40 is electrically connected to various sensors such as an accelerator position sensor 50, a crank position sensor 60, and a cam position sensor 70.

  The accelerator position sensor 50 is a sensor that outputs an electrical signal that correlates with the amount of operation of the accelerator pedal (accelerator opening). The crank position sensor 60 is a sensor that outputs an electrical signal correlated with the rotational position of the crankshaft. The cam position sensor 70 is a sensor that outputs an electrical signal correlated with the rotational position of the intake camshaft 1.

  The ECU 40 is electrically connected to various devices such as a fuel injection valve 107, a spark plug 108, a starter motor 80, and a variable valve mechanism 2 (OCV7 and OSV8). The ECU 40 controls the various devices described above based on the output signals of the various sensors described above. The starter motor 80 is an electric motor that generates power for rotating (cranking) the crankshaft when the internal combustion engine 100 is started.

  For example, when the operation of the internal combustion engine 100 is stopped, the ECU 40 operates the lock mechanism 20 in preparation for the next start (the OSV 8 makes the unlocking oil passage L7 and the third drain oil passage L6 conductive). .

  Incidentally, there is a possibility that the operation of the internal combustion engine 100 is stopped in a state where the lock pin 20a is not fitted into the locking hole 23b. When the internal combustion engine 100 is started in such a state, a sufficiently large hydraulic pressure cannot be applied to the variable valve mechanism 2 during cranking of the internal combustion engine 100. Therefore, there is a possibility that the internal combustion engine 100 is cranked in a state where the phase of the intake camshaft 1 is retarded from the reference phase, which may cause a decrease in startability.

  On the other hand, the phase of intake camshaft 1 is advanced to the reference phase by using the ratchet mechanism 27 and the torque that acts on intake camshaft 1 from valve spring 105a during the closing operation of intake valve 105. Therefore, a method of fixing (locking) the housing member 23 and the vane rotor 21 by the lock mechanism 20 is conceivable.

  Here, as shown in FIG. 8, the intake valve 105 is lifted out of Piv during a period from when the intake valve 105 starts to lift until it finishes lifting (that is, a period from when the intake valve 105 starts to open until it closes). In the period from the start until the maximum lift state is reached (valve opening operation period) Pivo, the reaction force of the valve spring 105a acts negatively on the force for rotating the intake camshaft 1. That is, during the valve opening operation period Pivo, the reaction force of the valve spring 105a acts to retard the intake camshaft 1.

  On the other hand, during the period until the intake valve 105 finishes lifting from the maximum lift state (valve closing operation period) Pivc, the reaction force of the valve spring 105a acts positively on the force for rotating the intake camshaft 1. That is, during the valve closing operation period Pivc, the reaction force of the valve spring 105a acts to advance the intake camshaft 1.

Therefore, when the ratchet mechanism 27 is operated during cranking of the internal combustion engine 100, the advance angle of the intake camshaft 1 by the reaction force of the valve spring 105a is allowed during the valve closing operation period Pivc, and the valve opening operation period. During Pivo, the retard angle of the intake camshaft 1 due to the reaction force of the valve spring 105a is regulated. At this time, the interval between the fitting grooves 23c of the ratchet mechanism 27 can be set to be equal to or less than the amount by which the intake camshaft 1 is advanced (the amount by which the vane rotor 21 rotates) during the valve closing operation period Pivc per one time. In this case, the intake camshaft 1 can be gradually advanced. Thus, the advance mechanism according to the present invention is realized by operating the ratchet mechanism 27.

  The amount by which the intake camshaft 1 is advanced during the valve closing operation period Pivc is greater when the crankshaft rotational speed (engine speed) is lower than when the crankshaft rotational speed is high. Therefore, when a part of the valve closing operation period of one cylinder overlaps with the valve opening operation period of the other cylinders, as in a four-cylinder four-stroke cycle engine, the engine speed during the valve closing operation period is reduced. Since the speed is decelerated by the reaction force of the valve springs of the other cylinders, the amount of advance of the intake camshaft during one valve closing operation period increases.

  On the other hand, in a two-cylinder four-stroke cycle engine such as the internal combustion engine 100, the valve closing operation period of one cylinder and the valve opening operation period of the other cylinders do not overlap. The engine speed tends to be high. As a result, the amount of advance of the intake camshaft during one valve closing operation period is reduced.

  Further, in a four-cylinder four-stroke cycle engine, the valve closing operation period occurs twice per one rotation of the crankshaft. In contrast, in a two-cylinder four-stroke cycle engine such as the internal combustion engine 100, the valve closing operation period occurs only once per crankshaft rotation. As a result, the amount of advance of the intake cam shaft per one rotation of the crankshaft is reduced.

  Therefore, in the two-cylinder internal combustion engine 100, since the time required for the phase of the intake camshaft 1 to advance to the reference phase becomes long, the power consumption of the starter motor 80 increases or the vehicle is started quickly. May be impossible.

  Therefore, during the cranking of the internal combustion engine 100, the ECU 40 reduces the engine speed when the rotational position of the intake camshaft 1 belongs to the valve closing operation period Pivc compared to when it does not belong to the valve closing operation period Pivc. I made it. Specifically, as shown in FIG. 9, the ECU 40 generates a torque generated by the starter motor (when the rotational position of the intake camshaft 1 belongs to the valve closing operation period Pivc, compared to when it does not belong to the valve closing operation period Pivc ( Torque reduction control for reducing the applied electric power of the starter motor 80 is performed.

  According to such torque reduction control, the advance amount of the intake camshaft 1 during one valve closing operation period is larger than that when torque reduction control is not executed (see the broken line in FIG. 9). The number of cases where torque reduction control is executed (see the solid line in FIG. 9) increases. As a result, the time required for the phase of the intake camshaft 1 to advance to the reference phase is shortened. Therefore, it is possible to avoid a situation where the power consumption of the starter motor 80 increases or a situation where the vehicle cannot be started quickly.

  Note that the rotation position of the crankshaft and the rotation position of the intake camshaft 1 are not synchronized under a situation where the phase of the intake camshaft 1 is not locked to the reference phase. Therefore, when the rotational position of the intake camshaft 1 is calculated from the output signal of the crank position sensor 60, there is a possibility that a deviation occurs between the calculated value and the actual rotational position.

  Further, in a situation where the phase of the intake camshaft 1 is not locked to the reference phase, the relative position of the intake camshaft 1 with respect to the crankshaft (in other words, the relative position of the vane rotor 21 with respect to the housing member 23) is not stable. There may be a deviation between the output signal of the position sensor 70 and the actual rotational position.

  When the above-described deviation occurs, the timing (torque reduction timing) for reducing the torque generated by the starter motor 80 is determined based on the output signals (sensor values) of the cam position sensor 70 and the crank position sensor 60. Then, a deviation also occurs between the start timing of the valve closing operation period Pivc and the torque reduction timing.

  Therefore, the ECU 40 uses the phenomenon that when the lift amount of the intake valve 105 exceeds the maximum lift amount, the engine speed is reversed (varied) from a decreasing tendency to an increasing tendency due to the reaction force of the valve spring 105a. The output signal was corrected. Specifically, the ECU 40 obtains the difference between the timing at which the cam position sensor 70 or the cam position sensor 70 detects the start timing Tpivc of the valve closing operation period Pivc and the timing at which the engine speed reverses from a decreasing tendency to an increasing tendency, The difference is added to the sensor value.

  When the sensor output signal is corrected in this way, the start timing of the valve closing operation period Pivc and the torque reduction timing can be synchronized. As a result, a decrease in the advance amount due to the difference between the sensor output signal and the actual timing is suppressed.

  Hereinafter, the execution procedure of the torque reduction control in the present embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing a control routine executed by the ECU 40 when the torque reduction control is performed. This control routine is a routine stored in advance in the ROM of the ECU 40, and is a routine that is executed with the start of cranking as a trigger.

  In the control routine of FIG. 10, the ECU 40 first determines whether or not cranking has started in S101. That is, the ECU 40 determines whether or not the operation switch (starter switch) of the starter motor 80 is turned on. If a negative determination is made in S101, the ECU 40 ends the execution of this routine. On the other hand, if a positive determination is made in S101, the ECU 40 proceeds to S102.

  In S102, the ECU 40 determines whether or not the intake camshaft 1 needs to be advanced (advance angle request). Specifically, the ECU 40 determines that the intake camshaft 1 needs to be advanced when the output signal of the cam position sensor 70 indicates a phase retarded from the reference phase. If a negative determination is made in S102, the ECU 40 ends the execution of this routine. On the other hand, when a positive determination is made in S102, the ECU 40 proceeds to S103.

  Subsequently, the ECU 40 reads the output signal (sensor value) of the cam position sensor 70 in S103, and determines whether or not the sensor value indicates the start timing Tpivc of the valve closing operation period Pivc in S104. If a negative determination is made in S104, the ECU 40 executes the processes after S103 again. On the other hand, if a positive determination is made in S104, the ECU 40 proceeds to S105.

  In S105, the ECU 40 determines whether or not a rotational fluctuation has occurred in which the engine rotational speed reverses from a decreasing tendency to an increasing tendency. If a negative determination is made in S105, the ECU 40 proceeds to S106. In S106, the ECU 40 corrects the sensor value. Subsequently, the ECU 40 proceeds to S107 and reduces the torque generated by the starter motor 80 (torque reduction processing) when the corrected sensor value coincides with the start timing Tpivc of the valve closing operation period Pivc. If an affirmative determination is made in S105, the ECU 40 skips the process of S106 and executes the process of S107.

Thus, when the ECU 40 executes the control routine of FIG. 10, the control unit according to the present invention is realized. Therefore, during cranking of the two-cylinder internal combustion engine 100, the phase of the intake camshaft 1 can be quickly locked to the reference phase. As a result, an increase in power consumption of the starter motor 80 can be avoided and the internal combustion engine 100 can be started quickly.

  In this embodiment, the variable valve mechanism for changing the phase of the intake camshaft is taken as an example of the variable valve mechanism according to the present invention. However, the variable valve mechanism for changing the phase of the exhaust camshaft is used. May be.

  In this embodiment, a spark ignition type internal combustion engine is exemplified as an internal combustion engine to which the present invention is applied, but a compression ignition type internal combustion engine (diesel engine) may be used.

DESCRIPTION OF SYMBOLS 1 Intake cam shaft 2 Variable valve mechanism 9 Oil pump 20 Lock mechanism 20a Lock pin 20b Spring 21 Vane rotor 21a Vane 21b Storage hole 21c Lock release hydraulic chamber 21d Piece storage hole 21e Ratchet release hydraulic chamber 22 Bolt 23 Housing member 23a Convex portion 23b Locking hole 23c Fitting groove 24 Sprocket 25 Retarded hydraulic chamber 26 Advanced hydraulic chamber 27 Ratchet mechanism 27a Frame 27b Spring 40 ECU
100 internal combustion engine 101 cylinder 103 intake port 105 intake valve 105a valve spring L2a first drain oil passage L2b second drain oil passage L3 retard oil passage L4 advance oil passage L5 branch oil passage L6 third drain oil passage L7 Unlocking oil passage L8 Ratchet releasing oil passage

Claims (2)

A variable valve mechanism that changes the phase of the camshaft relative to the crankshaft;
A lock mechanism that fixes the phase of the camshaft to a reference phase that is a phase suitable for starting an internal combustion engine;
A power generator for generating torque for cranking the internal combustion engine;
A start control system for a two-cylinder internal combustion engine equipped with
When cranking is started in a state where the camshaft is retarded from the reference phase, the camshaft phase is utilized using the torque acting from the valve spring to the camshaft during the valve closing operation period. An advance mechanism that advances the angle to the reference phase;
In the case where the advance mechanism advances the phase of the camshaft, when the rotational position of the camshaft belongs to the valve closing operation period, it does not belong to the valve closing operation period. A control unit for reducing the generated torque;
An internal combustion engine start control system comprising: The sensor according to claim 1, further comprising a sensor that detects a physical quantity correlated with the rotational position of the camshaft.
The control unit corrects the detection value of the sensor using the timing at which the engine rotational speed fluctuates as a parameter, and determines the timing for reducing the generated torque of the power generation device according to the corrected detection value. system.

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