JP2007132216A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, allowing the start of the engine while effectively suppressing vibration, even if the number of cylinders exceeds four. <P>SOLUTION: In the control device for an internal combustion engine, the internal combustion engine has a plurality of cylinders, and pistons disposed in each of the plurality of cylinders. The control device for an internal combustion engine has a positive rotation means moving a piston in the cylinder according to a combustion cycle of the internal combustion engine, and a reverse rotation means moving a piston in the cylinder so that the piston is rotated in a direction the reverse of the combustion cycle. The control device has a control means controlling the reverse rotation means. Before the start of the internal combustion engine, the piston is moved to be reversely rotated at a predetermined angle by the reverse rotation means so that cylinder pressure, of the the cylinder at a compression stroke after the start of the internal combustion engine, near a compression end point becomes small. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine. More specifically, the present invention relates to a control device that controls an internal combustion engine that includes a plurality of cylinders and a piston that moves in accordance with a combustion cycle.

  Japanese Patent Application Laid-Open No. 2002-61522 discloses a control system for an internal combustion engine having a variable valve mechanism that can change the valve opening characteristics of an intake valve. In this system, when the internal combustion engine is stopped, the intake valve is controlled so as to have a small lift amount and a small operating angle so that the valve closing timing (IVC) of the intake valve is greatly advanced from the bottom dead center. When the internal combustion engine is started, cranking is started in such a controlled state. At this time, since the intake valve is controlled to close early, the amount of intake air into the cylinder during the intake stroke is reduced. As a result, the in-cylinder pressure of the cylinder entering the compression stroke is reduced, and the compression pressure required to push up the piston of the cylinder is reduced. Thereby, according to the said prior art, generation | occurrence | production of the unpleasant vibration accompanying cranking at the time of internal combustion engine starting is suppressed.

  Further, when the piston is stopped in the vicinity of the bottom dead center, the atmosphere flows into the cylinder, so that the air amount in the cylinder is the atmospheric pressure corresponding to the position of the piston. In this case, the effect of reducing the compression pressure as described above cannot be obtained even if the intake valve is controlled to close early. However, in the above prior art systems, the piston is almost always stopped near the center of the stroke due to the dynamic balance action (subject to the force pushed back by the compression), and for further perfection. In some cases, the starting motor is controlled so that the piston stops near the center. Therefore, according to the above prior art system, the effect of reducing the compression pressure by the early closing of the intake valve can be obtained, and the vibration at the start of the internal combustion engine is suppressed.

JP 2002-61522 A

  In the above prior art, in order to reduce the compression pressure immediately after starting the internal combustion engine, the piston is not stopped near the top dead center and the bottom dead center. However, the above prior art is based on a four-cylinder internal combustion engine. With four cylinders, the interval between the cylinders can be set to 180 degrees during the 720 degree combustion cycle. For this reason, the piston can be stopped at a position 90 degrees away from the top dead center and the bottom dead center in all the cylinders. However, when there are more than four cylinders, the explosion interval in the combustion cycle of 720 degrees is shortened, and accordingly, the piston position interval is also shortened. Specifically, for example, in the case of eight cylinders, the pistons in each cylinder have an interval of 90 degrees in a combustion cycle of 720 degrees. In such a case, all pistons cannot be stopped at positions far from the top dead center and the bottom dead center, and the pistons of either cylinder will stop at positions close to the top dead center and the bottom dead center. .

  While the internal combustion engine is stopped, the atmosphere enters the cylinder, the atmospheric pressure inside the cylinder becomes atmospheric pressure, and the amount of air under atmospheric pressure corresponding to the piston position is sucked into the cylinder. For this reason, when the piston stops near the bottom dead center, the amount of air in the cylinder increases according to the stop position of the piston. As a result, the in-cylinder pressure has already increased due to the air sucked when the intake valve is stopped even when the intake valve is closed early. Accordingly, the compression pressure at the time of starting increases, and a large torque is required for pushing up the piston. As a result, vibration is generated when the internal combustion engine is started.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine that enables a start with effective vibration suppression even when the number of cylinders exceeds four. For the purpose.

In order to achieve the above object, a first invention provides a plurality of cylinders,
A control device for an internal combustion engine that controls an internal combustion engine comprising: a piston disposed inside each of the plurality of cylinders;
Forward rotation means for moving the piston in the cylinder according to a combustion cycle of an internal combustion engine;
A reverse rotation means for moving the piston in the cylinder in a reverse rotation to the combustion cycle before starting the internal combustion engine;
Control for moving the piston in the reverse rotation by the reverse rotation means so that the cylinder pressure in the vicinity of the compression end point of the cylinder in the compression stroke is reduced before the internal combustion engine is started. Means,
It is characterized by providing.

In a second aspect based on the first aspect, the internal combustion engine comprises:
An intake valve that is disposed in an intake port communicating with each of the plurality of cylinders, and that opens and closes the intake port at a predetermined timing in conjunction with movement of the piston;
An exhaust valve that is disposed in an exhaust port that communicates with each of the cylinders, and that opens and closes the exhaust port at a predetermined timing in conjunction with the movement of the piston,
The control means is configured such that at least one of the plurality of cylinders in a compression stroke after the start of the internal combustion engine exceeds a closing timing of the intake valve due to reverse rotation by the reverse rotation means. The reverse rotation is performed so as to rotate in reverse.

  In a third aspect based on the second aspect, the control means is a cylinder in a compression stroke after the start of the internal combustion engine by reverse rotation by the reverse rotation means among the plurality of cylinders. When the internal combustion engine is stopped, the cylinder where the stop position of the piston is stopped at a position closer to the bottom dead center than the stop position of the piston at the closing timing of the intake valve is the closing timing of the intake valve. 3. The control device for an internal combustion engine according to claim 2, wherein the reverse rotation is performed so as to reversely rotate beyond the range.

In addition, a fourth invention is any one of the first to third inventions,
The control means is configured such that, by reverse rotation by the reverse rotation means, the piston of a cylinder in the expansion stroke when the internal combustion engine is stopped among the plurality of cylinders at an angle determined within a range not exceeding top dead center It is characterized by moving.

  According to the first invention, before starting the internal combustion engine, the piston is moved in the reverse direction to the combustion cycle. As a result, immediately after the internal combustion engine is started, the in-cylinder pressure of the cylinder that first passes through the vicinity of the compression end point can be suppressed to a small level, and the vibration generated when the internal combustion engine is started can be suppressed to a small level.

  According to the second and third aspects of the invention, the reverse rotation angle is determined within a range in which the piston of at least one cylinder in the compression stroke rotates backward beyond the intake valve closing timing after the internal combustion engine is started. It is done. As a result, the in-cylinder pressure of the cylinder in the compression stroke can be reduced, and the compression pressure immediately after starting the internal combustion engine can be reduced.

  According to the fourth aspect of the invention, the reverse rotation angle is determined in a range in which the pistons of the cylinders in the expansion stroke when the internal combustion engine is stopped among the plurality of cylinders do not exceed the top dead center. Thereby, it can suppress that a vibration generate | occur | produces at the time of the movement of the piston by reverse rotation.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
[System configuration of the first embodiment]
FIG. 1 is a schematic diagram for illustrating a control system for an internal combustion engine according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram for illustrating an upper portion of the cylinder 4 according to the first embodiment. As shown in FIG. 1, the system of the first embodiment includes an internal combustion engine 2. The internal combustion engine 2 includes a cylinder 4. Although only a cross section of one cylinder 4 is shown in FIG. 1, the internal combustion engine 2 includes first to eighth cylinders 4 as described later. A piston 6 is disposed inside the cylinder 4. The piston 6 is connected to the crankshaft 10 via a connecting rod 8. In the vicinity of the crankshaft 10, a rotational speed sensor 12 for detecting the rotational speed is disposed.

  A combustion chamber 14 is provided above the piston 6 in the cylinder 4. An intake port 16 and an exhaust port 18 communicate with the combustion chamber 14. In FIG. 1, one intake port 16 and one exhaust port 18 connected to one cylinder 4 are shown. However, actually, as shown in FIG. 2, two intake ports 16 and two exhaust ports 18 communicate with the combustion chamber 14 of one cylinder 4. Referring to FIG. 1, a spark plug 20 is assembled in the combustion chamber 14 so that the tip portion is exposed. An injector 22 is assembled to the intake port 16. An electronically controlled throttle valve 24 and an air flow meter 26 are disposed upstream of the injector 22. On the other hand, an air-fuel ratio sensor 28 that emits an output corresponding to the exhaust air-fuel ratio is disposed in the exhaust port 18.

  The internal combustion engine 2 includes an intake valve 30 that opens and closes each intake port 16 and an exhaust valve 32 that opens and closes each exhaust port 18. The internal combustion engine 2 also includes an intake cam 34 that drives the intake valve 30 and an exhaust cam 36 that drives the exhaust valve 32. The intake cam 34 and the exhaust cam 36 are connected to the crankshaft 10 via cam pulleys, timing belts, and the like. The intake cam 34 and the exhaust cam 36 rotate in conjunction with the rotation of the crankshaft 10 to operate the intake valve 30 and the exhaust valve 32. As a result, the intake port 16 and the exhaust port 18 are opened and closed. The intake cam 34 is connected to a VVT mechanism (Variable Valve Timing Mechanism) 38 via a cam shaft or the like. It is assumed that the VVT mechanism 38 can change the operating angle and lift amount of the intake valve 30 via the intake cam 34. The exhaust cam 36 is connected to the VVT mechanism 40 via a cam shaft or the like. The VVT mechanism 40 can change the operating angle and lift amount of the exhaust valve 32 via the exhaust cam 36. Note that the structures of the VVT mechanism 38 and the VVT mechanism 40 are not particularly novel, and detailed description thereof is omitted here. A cam position sensor 42 that detects the rotational position of the cam is disposed in the vicinity of the intake cam 34, and a cam position sensor 44 is disposed in the vicinity of the exhaust cam 36.

  The internal combustion engine 2 includes an ECU (Electronic Control Unit) 46. The ECU 46 acquires information necessary for controlling the internal combustion engine 2 from various sensors such as the rotation speed sensor 12, the air flow meter 26, the air-fuel ratio sensor 28, and the cam position sensors 42 and 44. Moreover, based on the acquired information, the drive of the crankshaft 10, the spark plug 20, the injector 22, the throttle valve 24, and the VVT mechanisms 38 and 40 is controlled.

[Characteristic control of the system of the first embodiment]
FIG. 3 is a schematic diagram for explaining the state of each cylinder 4 when the internal combustion engine 2 is stopped. FIG. 4 is a diagram for explaining the valve timings of the intake valve 30 and the exhaust valve 32 when the internal combustion engine 2 is stopped. It is a valve timing diagram. FIG. 5 is a schematic diagram for explaining the state of each cylinder 4 when the internal combustion engine 2 is started. FIG. 6 shows the valve timings of the intake valve 30 and the exhaust valve 32 when the internal combustion engine 2 is started. It is a valve timing diagram for. In each figure, “IVO” represents the opening timing of the intake valve, “IVC” represents the closing timing of the intake valve, “EVO” represents the opening timing of the exhaust valve, and “EVC” represents the closing timing of the exhaust valve. Yes. Hereinafter, in the present embodiment, not only between the TDC (Top Dead Center) and BDC (Bottom Dead Center) of the piston 6, but also from the valve closing (IVC) of the intake valve, The stroke up to the TDC near the explosion / expansion start point (hereinafter referred to as “compression TDC”) is referred to as an “expanded compression stroke”.

  As shown in FIGS. 3 and 4, the internal combustion engine 2 has eight cylinders 4 of first to eighth cylinders. Each of the first to eighth numbers represents the combustion order, and is not necessarily arranged in the order of the numbers in the internal combustion engine 2. In addition, especially when each cylinder 4 is represented individually, the code | symbol of 4a-4h shall be attached | subjected corresponding to a 1st-8th cylinder. Moreover, in each figure, the number shown in (circle) shall show a cylinder number corresponding to the 1st-8th cylinder.

  When the internal combustion engine 2 is stopped, the pistons 6 of the first to eighth cylinders are stopped at the TDC, BDC, and their intermediate positions. Specifically, in the example of FIG. 3, the piston 6 of the fourth cylinder 4d stops at a TDC near the intake start point (hereinafter referred to as “intake TDC”), shifts by 90 degrees, and the piston 6 of the third cylinder 4c. Stops between the intake TDC and the BDC in the vicinity of the compression start point (hereinafter referred to as “compression BDC”), the piston 6 of the second cylinder 4b stops at the compression BDC, and the piston 6 of the first cylinder 4a becomes the compression BDC. And stop with the compressed TDC. The piston 6 of the eighth cylinder 4h stops at the position of the compression TDC, and shifts by 90 degrees, so that the piston 6 of the seventh cylinder 4g and the BDC after explosion / expansion (hereinafter referred to as “exhaust BDC”). The piston 6 of the sixth cylinder 4f stops at the exhaust BDC, and the piston 6 of the fifth cylinder 4e stops at an intermediate position between the exhaust BDC and the intake TDC.

  As shown in FIG. 4, the intake valve 30 is closed at an early closing timing, specifically, near the middle between the intake TDC and the compression BDC. On the other hand, the exhaust valve 32 is opened at an early opening timing, specifically, at an earlier timing than the exhaust BDC. At the time of stopping and at the start of starting, the VVT mechanisms 38 and 40 are locked in a state set at this timing, and the intake valve 30 and the exhaust valve 32 operate in conjunction with the rotation of the crankshaft 10, that is, the movement of the piston 6. .

  When the internal combustion engine 2 stops in the above state, the atmosphere gradually enters the cylinders 4 from the outside. As a result, the in-cylinder pressure becomes atmospheric pressure. If the stroke capacity (displacement amount) of each cylinder 4 at atmospheric pressure is 1, and the capacity of the combustion chamber 14 is α, the air amount of the second and sixth cylinders 4b and 4f in which the piston 6 moves to BDC is 1+. The amount of air in the fourth and eighth cylinders 4d, 4h at α, TDC is α, the third, first, seventh, fifth cylinders 4c, 4a, 4f, where the piston 6 is stopped at an intermediate position between BDC and TDC. The amount of air in 4e is 1/2 + α. If the mechanical compression ratio is ε, α is α = 1 / (ε-1).

  In the first embodiment, immediately before the internal combustion engine 2 is started, the crankshaft 10 is reversely rotated 90 degrees from the state of FIGS. 3 and 4 to the state of FIGS. As a result, as shown in FIGS. 5 and 6, the piston 6, the intake valve 30, and the exhaust valve 32 of each of the first to eighth cylinders 4 are returned to the positions reversely rotated by 90 degrees. Specifically, the third cylinder 4c is returned to the vicinity of the intake stroke start point. The piston 6 returns from the intermediate position between the TDC and the BDC to the vicinity of the intake TDC, and the cam rotates in reverse in conjunction with this. The second cylinder 4b is returned to a position slightly advanced from the IVC of the intake stroke, and the intake valve is opened. Further, the piston 6 of the second cylinder 4b rises to an intermediate position between TDC and BDC. The first cylinder 4a is reversely rotated during the expansion compression stroke, and the piston 6 descends to BDC. The eighth cylinder 4h is returned to the compression stroke, and the piston 6 descends to an intermediate position between BDC and TDC. The seventh cylinder 4g is returned to the vicinity of the expansion stroke start point, and the piston 6 rises to TDC. The sixth cylinder 4f is returned to the expansion stroke, and the piston 6 rises to an intermediate position between TDC and BDC. The fifth cylinder 4e is returned in the exhaust stroke, and the piston 6 descends to BDC. The fourth cylinder 4d is returned to the exhaust stroke, and the piston 6 descends to an intermediate position between TDC and BDC.

  As described above, when the crankshaft 10 is reversely rotated by 90 degrees, the amount of air in each cylinder 4 changes as follows. In the third cylinder 4c, with the intake valve 30 open, the piston 6 rises from its original position and the volume in the cylinder decreases, so the amount of air in the cylinder decreases to α. For the second cylinder 4b, the piston 6 rises from its original position, and the intake valve 30 opens at IVC, so the amount of air in the cylinder decreases to 1/2 + α.

  Regarding the first cylinder 4a, the piston 6 descends to BDC, so the volume in the cylinder 4a increases. However, since both the intake valve 30 and the exhaust valve 32 are closed, the air amount 1/2 + α in the cylinder 4a is not changed and is maintained as it is. This air amount 1/2 + α is the air amount when the piston 6 is at an intermediate position between BDC and TDC under atmospheric pressure, and when the piston 6 is at BDC, the air amount 1/2 + α is in the cylinder 4a under atmospheric pressure. The amount of air is 1 + α. Accordingly, the in-cylinder pressure in the first cylinder 4a is low. Also, for the eighth cylinder 4h, the piston 6 descends from the compression TDC to the middle position of the stroke, so the volume of the cylinder 4h increases. However, since both the intake valve 30 and the exhaust valve 32 are closed, the air amount α when the internal combustion engine 2 is stopped is maintained as it is. This air amount α is the air amount when the piston 6 is located at the BDC under atmospheric pressure, and the air amount in the cylinder 4 under the atmospheric pressure is ½ when the piston 6 is in the middle position of the stroke. + α. Therefore, the in-cylinder pressure is low in the eighth cylinder 4h.

  As for the seventh cylinder 4g, the piston 6 rises from the stop position and the volume in the cylinder 4g decreases. However, since both the intake valve 30 and the exhaust valve 32 are closed, the air amount is maintained as it is. α. For the sixth cylinder 4f, the piston 6 rises from the original position, and the volume in the cylinder 4f decreases. During this ascent, the exhaust valve 32 is open for a while. Accordingly, in the sixth cylinder 4f, part of the air is discharged in conjunction with the rise of the piston 6, and the amount of air in the cylinder 4f decreases to about 1/2 + α. As for the fifth and fourth cylinders 4e and 4d, the piston 6 descends from the original position and the volume in the cylinders 4e and 4f increases. At this time, since the exhaust valve 32 is in an open state, the air is sucked, and the amount of air increases to 1 + α and 1/2 + α in accordance with the position of the piston 6.

  By the way, the largest cause of the vibration occurring at the start of the internal combustion engine 2 is the vicinity of the compression end point (hereinafter referred to as “compression end”), that is, in the first embodiment, the piston 6 is pushed up near the compression TDC. It is power. Therefore, when the cylinder pressure at the compression end is large, a large torque is required to push up the piston 6. In particular, in a state where the torque immediately after starting is not ensured, if a large torque is required at the compression end, the torque fluctuation increases and causes vibration. Therefore, the vibration at the time of starting can be suppressed by reducing the torque required at the compression end.

  In this regard, the first embodiment is stopped in the state shown in FIGS. 3 and 4, and the crankshaft 10 is reversely rotated 90 degrees as shown in FIGS. As a result, the second cylinder 4b in the vicinity of the compression BDC and having the maximum amount of air in the cylinder 1 + α before the reverse rotation is returned immediately before the IVC of the intake stroke, and the intake valve is opened. It becomes a state and the air volume decreases to 1/2 + α. Thereafter, the intake valve 30 is immediately closed after starting the internal combustion engine 2 in the normal rotation, so that the air amount in the second cylinder 4b enters the expansion compression stroke with 1/2 + α. Therefore, compared with the air amount (1 + α) of the second cylinder when entering the expansion compression stroke without performing reverse rotation, the amount of air compressed in the expansion compression stroke can be greatly reduced. As a result, the in-cylinder pressure at the compression end can be reduced, and the occurrence of vibration can be suppressed.

  Further, when starting the internal combustion engine 2 in the forward rotation after the reverse rotation, the cylinder that first passes through the compression end of the compression stroke is the eighth cylinder 4h. Here, even during reverse rotation of the eighth cylinder 4h, the piston 6 is pulled back to an intermediate position between the TDC and the BDC without increasing the air amount in the cylinder 4h by the intake valve 30 while maintaining α. It has become. That is, the air amount (α) of the eighth cylinder 4h is smaller than the normal air amount (1/2 + α) at the piston position at the start of the start. Therefore, the in-cylinder pressure at the compression end in the eighth cylinder 4h is small, and the occurrence of vibration can be suppressed. Further, after the eighth cylinder 4h, the first cylinder 4a passes through the compression end. The first cylinder 4a is in a state in which the piston 6 is pulled back to the compression BDC without increasing the air amount in the cylinder 4a in a state of 1/2 + α due to reverse rotation. Therefore, the in-cylinder pressure in the first cylinder 4a is small. As a result, vibration can be further reduced.

  Further, after starting, the cylinders other than the second, eighth, and first cylinders that first enter the expansion compression stroke are controlled so that the IVC of the intake valve 30 is at the timing of early closing, thereby vibrating. Occurrence is suppressed. That is, since the intake valve 30 is closed near the middle between the intake TDC and the compression BDC, the amount of air taken into the cylinder 4 before the expansion compression stroke becomes 1/2 + α. Accordingly, the in-cylinder pressure at the compression end of the compression stroke is suppressed to a small value, and the occurrence of vibration at the compression end is suppressed.

  7 and 8 are flowcharts for illustrating a control routine executed by the control apparatus according to the first embodiment of the present invention. The routine of FIG. 7 is a routine that is executed every time the internal combustion engine 2 is stopped. In the routine of FIG. 7, it is first determined whether or not an instruction to stop the internal combustion engine 2 has been issued (step S102). Whether the internal combustion engine 2 is instructed to stop is, for example, in the case of an HV vehicle, whether there is an instruction from the HV control, or whether the ignition switch is turned off by the driver when the internal combustion engine 2 is not being stopped. Is determined. If the stop instruction for the internal combustion engine 2 is not accepted in step S102, this process is terminated. When a stop instruction for the internal combustion engine 2 is accepted in step S102, control at the time of stop is performed (step S104). Specifically, at the time of stopping, as shown in FIGS. 3 and 4, the pistons 6 of two cylinders 4 (fourth and eighth cylinders in FIG. 3) are set to TDC and two cylinders (FIG. 3). In FIG. 3, the pistons 6 of the second and sixth cylinders are BDC, and the pistons 6 of the remaining cylinders 4 (first, third, fifth, and seventh cylinders in FIG. 3) are TDC and BDC, respectively. It is controlled to be located between. On the other hand, the intake valve 30 and the exhaust valve 32 are controlled by adjusting the angles of the intake cam 34 and the exhaust cam 36 so that the timing of early closing is reached.

  The routine of FIG. 8 is a routine that is executed every time at the starting temple of the internal combustion engine 2. In the routine of FIG. 8, it is first determined whether or not the start of the internal combustion engine 2 is instructed (step S106). Whether the internal combustion engine 2 is instructed to start is, for example, in the case of an HV vehicle, if there is an instruction to start from HV control, and if the stop control of the internal combustion engine 2 at idling is not performed, the ignition switch is turned on by the driver. It is determined by whether or not it has been. In step S106, when the start instruction of the internal combustion engine 2 is not recognized, this process is terminated.

  On the other hand, when the start of the internal combustion engine 2 is recognized in step S106, the crankshaft 10 of the internal combustion engine 2 is reversely rotated by 90 degrees (step S108). As a result, among the cylinders that enter the expansion compression stroke when the internal combustion engine 2 is started, in particular, the cylinder in which the piston 6 is stopped near the BDC and the amount of air in the cylinder is large (the second cylinder 4b in FIG. 5). ) Is rotated back to IVC. As a result, the intake valve 30 is opened, and the amount of air in the second cylinder 4b is reduced to 1/2 + α in accordance with the position of the piston 6 (intermediate between TDC and BDC) at that time. Similarly, the pistons 6 of the other cylinders 4 (in FIG. 5, the eighth cylinder 4h and the first cylinder 4a) that enter the expansion compression stroke when the internal combustion engine 2 starts are kept unchanged in the internal air amount. Pulled back. As a result, the amount of air in the cylinder 4 is small with respect to the position of the piston 6, and the in-cylinder pressure is small.

  Next, the internal combustion engine 2 is started (step S110). Here, after starting, the cylinder (the second cylinder 2b in FIG. 5) in which the piston 6 has stopped in the vicinity of the BDC is started to reversely rotate until the timing of IVC. Therefore, the amount of air in the cylinder 4 is small. Therefore, the pressure at the compression end of the cylinder 4 is small. Further, in the other cylinders (the first cylinder 4a and the eighth cylinder 4h in FIG. 5) that enter the expansion compression stroke after start-up, the air amount does not increase even by reverse rotation. Therefore, it is possible to pass through the compression end while the in-cylinder pressure is small. Accordingly, the pressure at the compression end in the expansion compression stroke after the start of the internal combustion engine 2 is reduced. As a result, vibrations generated when the internal combustion engine 2 is started can be reduced.

  In the first embodiment, the description has been given of the case where the piston 6 is stopped at the TDC and the BDC and the reverse rotation of 90 degrees is performed at the start in four of the eight cylinders. However, the present invention is not limited to this. The stop position and the valve timing may be determined in consideration of the normal traveling state. At the time of starting, the reverse rotation angle is determined in consideration of the stop position of the piston 6 and the valve timing, and the crankshaft 10 is just before the start at the angle. May be reversed. That is, when the internal combustion engine 2 is stopped, the piston 6 is stopped at a position closer to the BDC than the position of the piston 6 in the IVC, and before starting the reverse rotation, before the IVC is exceeded. In the cylinder that enters the expansion compression stroke, the cylinder that enters the expansion compression stroke after the start is specified by reverse rotation, and the reverse rotation is performed until the cylinder exceeds IVC.

  In addition, when the compression TDC is exceeded by pushing up the piston 6 of the cylinders in the expansion stroke at the time of reverse rotation (sixth and seventh cylinders 4f and 4g in FIG. 5), vibration may be generated at the time of reverse rotation. Therefore, in the case of reverse rotation, it is preferable that the cylinder in the expansion stroke is in a range not exceeding TDC. Alternatively, even if the cylinder in the expansion stroke exceeds TDC, the cylinder 6 in which the stop position of the piston 6 when the internal combustion engine is stopped is stopped at a position closer to the BDC than the piston position in IVC is reversely rotated. Therefore, it is preferable to keep it within a range not exceeding TDC. Thereby, generation | occurrence | production of a vibration can be suppressed more effectively.

  In the first embodiment, the valve timing is controlled by the VVT mechanisms 38 and 40 via the intake cam 34 and the exhaust cam 36, and the intake valve 30 and the exhaust valve 32 are opened and closed in conjunction with the rotation of the crankshaft 10. Explained the case. However, the valve timing control mechanism is not limited to this, and other control mechanisms such as those capable of operating the intake valves 30 and the exhaust valves 32 individually may be used.

Embodiment 2. FIG.
The system configuration of the second embodiment is the same as that of the first embodiment except that the number of cylinders 4 of the internal combustion engine 2 is four. FIG. 9 is a schematic diagram for explaining the state of the cylinder when the internal combustion engine 2 is stopped in the second embodiment. FIG. 10 is a valve timing diagram for explaining the valve timing when the internal combustion engine 2 is stopped. As shown in FIG. 9, in the example of the second embodiment, the internal combustion engine 2 has first to fourth four cylinders 4a to 4d. When the internal combustion engine 2 is stopped, each piston 6 of each cylinder 4 is stopped at, for example, compression BDC, intake TDC, exhaust BDC, and compression TDC. After stopping, the inside of each cylinder 4 is replaced with air. As a result, the amount of air in the second and fourth cylinders 4b and 4d with the piston 6 at TDC is α, and the amount of air in the first and third cylinders 4a and 4c with the piston 6 at BDC is 1 + α. Become. As shown in FIG. 10, the intake valve 30 is closed at the timing of early closing, and the exhaust valve 32 is controlled via the intake cam 34 and the exhaust cam 36 so as to be opened and closed at the timing of early opening.

  FIG. 11 is a schematic diagram for explaining the state of each cylinder when the crankshaft 10 is rotated 90 degrees reversely at the start of the internal combustion engine 2, and FIG. 12 is a diagram for explaining the valve timing at the start. It is a valve timing diagram. In the second embodiment, as in the first embodiment, the crankshaft 10 is reversely rotated 90 degrees at the start. At this time, as shown in FIG. 11, each piston 6 of each cylinder 4 is disposed at an intermediate position between TDC and BDC. Specifically, since the first cylinder 4a is returned to the timing just before the intake valve 30 is closed, the intake valve 30 opens at the time of reverse rotation by 90 degrees, and the pressure in the first cylinder 4a becomes atmospheric pressure. The amount of air in the cylinder 4a decreases from 1 + α to 1/2 + α. The fourth cylinder 4d is returned halfway from the compression TDC to the middle of the stroke. During this time, both the intake valve 30 and the exhaust valve 32 are closed. Accordingly, the amount of air in the fourth cylinder 4d does not change from α, and the in-cylinder pressure of the fourth cylinder 4d decreases. The third cylinder 4c is returned in the middle of the expansion stroke. At this time, since the opening timing of the exhaust valve 32 is advanced, the exhaust valve 32 is in the open state during reverse rotation, and the piston 6 is returned while the air in the third cylinder 4c is exhausted. . Therefore, the inside of the third cylinder 4c is almost close to the atmospheric pressure, and the air amount is reduced from 1 + α to about 1/2 + α. The second cylinder 4b is returned in the middle of the exhaust stroke. At this time, since the exhaust valve 32 is opened, the in-cylinder pressure of the second cylinder 4b becomes atmospheric pressure, and the air amount increases from α to 1/2 + α.

  As described above, when the internal combustion engine 2 is started, the largest torque is required, and the vibration is caused by the force when the piston 6 is pushed up at the compression end of the compression stroke. Here, the cylinders that enter the expansion compression stroke immediately after the internal combustion engine 2 is started due to the reverse rotation are the fourth cylinder 4d and the first cylinder 4a. In particular, since the piston of the first cylinder 4a is in the BDC when the internal combustion engine 2 is stopped, the amount of air in the cylinder is large. However, the first cylinder 4a is advanced and returned from IVC by reverse rotation. That is, in the first cylinder 4a, the intake valve 30 is opened when the piston 6 comes near the intermediate position between TDC and BDC due to reverse rotation. As a result, the air in the piston 6 is discharged, and the air amount is reduced to 1/2 + α corresponding to the position of the piston 6. Therefore, after the internal combustion engine 2 is started, the in-cylinder pressure when the first cylinder 4a passes through the compression end can be reduced, and the occurrence of vibration at the start of the internal combustion engine 2 can be suppressed. Further, in the second embodiment, the fourth cylinder 4d is in a state where the in-cylinder pressure is small because the position of the piston 6 is returned by the reverse rotation while the air amount α remains unchanged. Accordingly, the torque fluctuation at the compression end of the compression stroke after the start as a whole can be suppressed as the internal combustion engine 2 as a whole, and the vibration generated at the start can be suppressed small. The control in the second embodiment as described above is performed in the same routine as in FIGS.

  In the second embodiment, the case where the piston of each cylinder 4 is stopped at TDC or BDC as shown in FIGS. 9 and 10 has been described. However, the stop position of the piston is not limited to this. FIG. 13 is a valve timing diagram for explaining another example of stopping in the second embodiment of the present invention. In the example shown in FIG. 13, the piston 6 of each cylinder 4 is controlled to stop near the intermediate position of each stroke between TDC and BDC. In this case, when the cylinders 4 are stopped, the cylinders 4 are replaced with air, so that the in-cylinder pressures of the first to fourth cylinders become atmospheric pressure, and the air amount becomes 1/2 + α. In this example, the pistons 6 of all the cylinders 4 are stopped at substantially the same position as the position of the piston 6 in IVC. Therefore, even if any cylinder that enters the expansion compression stroke after starting the internal combustion engine 2 is advanced beyond IVC by reverse rotation, the amount of air in the cylinder 4 is reduced more than when stopped. I can't. Therefore, in such a case, that is, when there is no cylinder 4 that is closer to the BDC than the position of the piston 6 among the cylinders that enter the expansion compression stroke after starting, the effect of reverse rotation can be obtained. I can't. In such a case, it is only necessary to start the internal combustion engine 2 as usual without performing reverse rotation. In the second embodiment, even when starting without performing reverse rotation, the IVC is advanced, so the amount of compressed air in the expansion compression stroke is 1/2 + α. Therefore, vibration at the time of starting can be suppressed.

  Further, the above-described control in the case of not performing the reverse rotation is combined with the control in the case of performing the reverse rotation, for example, the reverse rotation is required from the stop position of the piston 6 between step S106 and step S108 in FIG. In addition to the step of determining whether or not reverse rotation is necessary, it is possible to perform control such that reverse rotation is performed in step S108 only when it is determined that reverse rotation is necessary.

  As described above, the stop position, the valve timing, and the reverse rotation angle at the start are not limited to the examples described in the second embodiment. The stop position and valve timing may be determined in consideration of the normal running state. At the time of starting, the reverse rotation angle is determined in consideration of the stop position of the piston 6 and the valve timing. That is, a cylinder that enters an expansion compression stroke after starting due to reverse rotation and in which the piston 6 is stopped at a position closer to the BDC than the piston position of the IVC is specified, and this cylinder is advanced beyond the IVC. What is necessary is just to calculate the angle which is performed and to reversely rotate. As a result, the amount of air in the cylinder can be made smaller than the amount of air at the time of stop, the in-cylinder pressure of the cylinder at the compression end of the compression stroke at the start can be reduced, and the occurrence of vibration due to torque fluctuation can be suppressed. .

  In the above embodiment, the case of four cylinders and eight cylinders has been described. However, the present invention is not limited to this. For example, the present invention can also be applied to the case of six cylinders. Even in this case, it is only necessary to be able to reduce the air in the cylinder passing through the compression end of the expansion compression stroke after the internal combustion engine 2 is started, and as a result, the vibration at the start can be suppressed to a small level. .

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., unless otherwise specified or clearly specified in principle, the number referred to It is not limited. Further, the structures described in the embodiments, steps in the method, and the like are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

It is a schematic diagram for demonstrating the structure of the system in Embodiment 1 of this invention. It is a figure showing the cylinder upper part of 1 of the internal combustion engine in Embodiment 1 of this invention. It is a figure showing the state of each cylinder at the time of the stop of the internal combustion engine in Embodiment 1 of this invention. It is a figure showing the state of each cylinder at the time of the stop of the internal combustion engine in Embodiment 1 of this invention. It is a figure showing the state of each cylinder at the time of start-up of the internal combustion engine in Embodiment 1 of this invention. It is a figure showing the state of each cylinder at the time of start-up of the internal combustion engine in Embodiment 1 of this invention. It is a flowchart for demonstrating the routine of control which a control apparatus performs in Embodiment 1 of this invention. It is a flowchart for demonstrating the routine of control which the control apparatus in Embodiment 1 of this invention performs. It is a figure showing the state of each cylinder at the time of the stop of the internal combustion engine in Embodiment 2 of this invention. It is a figure showing the state of each cylinder at the time of the stop of the internal combustion engine in Embodiment 2 of this invention. It is a figure showing the state of each cylinder at the time of the starting of the internal combustion engine in Embodiment 2 of this invention. It is a figure showing the state of each cylinder at the time of the starting of the internal combustion engine in Embodiment 2 of this invention. It is a figure showing the state of each cylinder at the time of the other stop of the internal combustion engine in Embodiment 2 of this invention.

Explanation of symbols

2 Internal combustion engine 4 Cylinder 6 Piston 8 Connecting rod 10 Crankshaft 12 Rotational speed sensor 14 Combustion chamber 16 Intake port 18 Exhaust port 20 Spark plug 22 Injector 24 Throttle valve 26 Air flow meter 28 Air-fuel ratio sensor 30 Intake valve 32 Exhaust valve 34 Intake cam 36 Exhaust cam 38 VVT mechanism 40 VVT mechanism 42 Cam position sensor 44 Cam position sensor 46 Control device

Claims (4)

Multiple cylinders,
A control device for an internal combustion engine that controls an internal combustion engine comprising: a piston disposed inside each of the plurality of cylinders;
Forward rotation means for moving the piston in the cylinder according to a combustion cycle of an internal combustion engine;
A reverse rotation means for moving the piston in the cylinder in a reverse rotation to the combustion cycle before starting the internal combustion engine;
Control for moving the piston in the reverse rotation by the reverse rotation means so that the cylinder pressure in the vicinity of the compression end point of the cylinder in the compression stroke is reduced before the internal combustion engine is started. Means,
A control device for an internal combustion engine, comprising: The internal combustion engine
An intake valve that is disposed in an intake port communicating with each of the plurality of cylinders, and that opens and closes the intake port at a predetermined timing in conjunction with movement of the piston;
An exhaust valve that is disposed in an exhaust port that communicates with each of the cylinders, and that opens and closes the exhaust port at a predetermined timing in conjunction with the movement of the piston,
The control means is configured such that at least one of the plurality of cylinders in a compression stroke after the start of the internal combustion engine exceeds a closing timing of the intake valve due to reverse rotation by the reverse rotation means. The control device for an internal combustion engine according to claim 1, wherein reverse rotation is performed so as to reversely rotate.   The control means is a cylinder in a compression stroke after the start of the internal combustion engine due to reverse rotation by the reverse rotation means among the plurality of cylinders, and when the internal combustion engine is stopped, the stop position of the piston is The cylinder stopped at a position closer to bottom dead center than the piston stop position at the closing timing of the intake valve performs reverse rotation so as to reversely rotate beyond the closing timing of the intake valve. The control apparatus for an internal combustion engine according to claim 2, wherein the control apparatus is an internal combustion engine.   The control means is configured such that, by reverse rotation by the reverse rotation means, the piston of a cylinder in the expansion stroke when the internal combustion engine is stopped among the plurality of cylinders at an angle determined within a range not exceeding top dead center The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein

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