JP4581273B2 - Start-up control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a start control device for improving startability at low temperatures of an internal combustion engine, and in particular, variable valve means capable of variably controlling the closing timing of an intake valve, and variably controlling a compression ratio (nominal compression ratio ε) of the internal combustion engine. The invention relates to a technology for improving startability at a low temperature of a gasoline engine provided with a compression ratio control means.
[0002]
[Prior art]
The present applicant has previously proposed a variable valve mechanism capable of continuously increasing and reducing the lift and operating angle of the intake valve (for example, JP-A-11-107725, JP-A-11-324625). In addition, a variable valve mechanism has been proposed in which a significant degree of freedom in lift characteristics is obtained in combination with a mechanism that retards the phase of the center angle of the lift.
[0003]
As a variable compression ratio mechanism of a reciprocating internal combustion engine, a mechanism using a multi-link type piston-crank mechanism has been proposed in recent years, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-73804.
[0004]
[Problems to be solved by the invention]
At extremely low temperatures such as -40 ° C, not only is the temperature of the intake air flowing into the cylinder low, but the temperature of the structure that constitutes the combustion chamber such as the piston and cylinder is also low. descend. In addition to this, fuel vaporization and atomization become insufficient, and the formation of the air-fuel mixture also deteriorates. Further, at such a low temperature, the capacity of the battery mounted on the vehicle is generally reduced, and the viscosity of the oil is high, so that the cranking rotation by the starter motor does not readily increase. This is also a factor that hinders quick start-up.
[0005]
For such deterioration in starting performance at extremely low temperatures, some energy is used to increase the temperature inside the cylinder, such as an intake control valve that promotes atomization of fuel and a glow plug used in diesel engines. The means to add directly to the cylinder and the means to increase the intake air temperature by attaching a heater to the intake port have already been put into practical use. The key point is to raise it.
[0006]
In order to increase the mixture temperature, it is essential to increase the compression ratio, particularly the actual compression ratio.
[0007]
The present invention provides control of compression ratio control means that variably controls the geometric compression ratio of the internal combustion engine, that is, the nominal compression ratio ε, and variable valve means that affects the closing timing of the intake valve that affects the actual compression ratio. The object is to improve the startability, particularly at low temperatures, by combining them.
[0008]
Activation control apparatus for an internal combustion engine according to claim 1, the piston such that the variable valve means for variably controlling the closing timing of the intake valve of the internal combustion engine is a gasoline engine, a nominal compression ratio with increasing load drops An internal combustion engine having a compression ratio control means for variably controlling the nominal compression ratio of the internal combustion engine by changing the position, and at the time of engine startup, the nominal compression ratio is maintained at a high compression ratio equivalent to that at idling by the compression ratio control means. With the variable valve mechanism, the intake valve closing timing is set to a timing away from the bottom dead center at the initial stage of cranking, and the intake valve closing timing is brought close to the bottom dead center after the cranking starts.
[0009]
For example, in idle and partial load ranges, pump loss can be reduced by making the intake valve closing timing earlier than the bottom dead center, but if the nominal compression ratio of the internal combustion engine is constant, the intake valve closing timing is set to the bottom dead center. If it is made earlier, the actual compression ratio will decrease. Therefore, in the present invention, the variable valve means and the compression ratio control means are set so that the actual compression ratio during cranking is optimal in terms of startability, taking into account the fluctuation of the actual compression ratio due to the intake valve closing timing. And control.
[0011]
That is, when the nominal compression ratio ε is high, the number of cranking rotations by the starter motor tends to be low. If the cranking speed is low, the first explosion will not occur even if the air-fuel mixture is ignited. Therefore, in the initial stage, an increase in the cranking speed is prioritized .
[0014]
If the intake valve closing timing is set away from the bottom dead center to the retard side or advance side at the initial stage of cranking , the actual compression ratio will decrease even if the compression ratio (nominal compression ratio ε) is increased. A so-called decompression action that reduces the compression during cranking is obtained. As a result , the cranking speed increases. Then, when brought closer to the intake valve closing timing after the cranking start to the bottom dead center, the actual compression ratio is increased, increase in gas mixture temperature Ru Hakare.
[0015]
According to a third aspect of the present invention, the compression ratio control means comprises a multi-link piston-crank mechanism, and is configured such that the reciprocating motion of the piston with respect to the rotation of the crankshaft has a stroke characteristic close to a single vibration motion. Yes. The stroke characteristics close to the single vibration motion are advantageous in terms of noise and vibration. In particular, the piston speed near the top dead center is a general single link piston-crank mechanism. Compared to, it will be 20% slower. This is because, in particular, under conditions where the combustion speed is slow, such as when cold, the initial flame kernel is generated and grows, so that a large time margin is given to stabilize the combustion. effective.
[0016]
In the invention according to claim 4, the variable valve means includes a lift / operating angle variable mechanism capable of simultaneously and continuously expanding and reducing the lift / operating angle of the intake valve, and at the time of engine cold start, The lift / working angle of the intake valve is controlled to a small lift / working angle equivalent to idling .
[0017]
In the invention according to claim 5, the variable valve means includes a phase variable mechanism for delaying the phase of the lift center angle of the intake valve, and after the cranking starts, the intake valve closing timing falls to the bottom. The lift center angle is retarded so as to approach the bottom dead center from the position before the point.
[0018]
In the invention of claim 6 further restricting the invention of claim 5, the variable valve operating means is a lift / working angle variable mechanism capable of simultaneously and continuously expanding and reducing the lift / working angle of the intake valve. And the phase variable mechanism, and in accordance with the lift / working angle, the delay angle of the lift center angle is increased when the lift / working angle is small. .
[0019]
That is, by reducing the lift center angle while reducing the lift / operation angle, the intake valve closing timing approaches the bottom dead center, and the actual compression ratio increases. At the same time, the intake valve opening timing comes later than the top dead center, and after the negative pressure develops in the first half of the intake stroke, the intake valve starts to open with a small lift. Therefore, the intake air flows into the cylinder at the speed of sound, and the fuel and air flow at a high speed, which is extremely advantageous for air-fuel mixture formation, and atomization and vaporization are promoted. Further, since such flow velocity energy is finally converted into heat energy, there is an effect of increasing the intake air temperature. Therefore, by simultaneously increasing the geometric compression ratio ε, the mixture temperature at the compression top dead center rises to a sufficient temperature, leading to the first explosion.
[0020]
The compression ratio control means, for example as in claim 7, a first link connected via a piston pin to the piston, a crank pin of the crankshaft while being swingably connected to the first link The second link is rotatably connected to the second link, and the third link is swingably connected to the second link and is swingably supported by the engine body. In such a multi-link piston-crank mechanism, stroke characteristics close to the single vibration motion as described above can be easily obtained by appropriately setting the alignment of each link and fulcrum.
[0021]
Then, this structure, for example as in claim 8, it is possible to perform variable control of the compression ratio by changing depending fulcrum position the engine operating conditions for the engine body of the third link. That is, as the fulcrum position of the third link changes, the piston position at the top dead center of the piston changes, and the nominal compression ratio ε changes.
[0022]
The lift operating angle variable mechanism, for example, as according to claim 9, parallel to the eccentric cam that is driven to rotate, and a link arm fitted relatively rotatably on the outer periphery of the eccentric cam, and the drive shaft by the drive shaft A pivotable control shaft provided with an eccentric cam portion, a rocker arm rotatably mounted on the eccentric cam portion of the control shaft and swung by the link arm, and rotated on the drive shaft And an oscillating cam that presses the tappet of the intake valve by oscillating along with the rocker arm and oscillating along with the rocker arm. The lift and operating angle of the intake valve are configured to increase and decrease simultaneously by changing the rotational position of the part.
[0023]
Also the phase variable mechanism, for example, as according to claim 1 0, a cam sprocket is rotatably driven by the crankshaft via a chain or a timing belt, a cam shaft driven to rotate by the cam sprocket, said cam sprocket And a mechanism for changing the phase with the camshaft.
[0024]
In particular, even in the extremely low temperature of the battery capacity is reduced, it is possible to sufficiently increase the cranking rotation speed, it is possible to reliably start.
[0025]
In particular, according to the second to fourth aspects, the cranking rotation speed can be sufficiently increased even at an extremely low temperature when the battery capacity is lowered, and the start-up can be started more reliably.
[0026]
Further, if the multi-link type piston-crank mechanism constituting the compression ratio control means has a stroke characteristic close to a single vibration motion as in claim 3 , the piston speed near the top dead center becomes a general single speed. Since it becomes gentler than that of the link type piston-crank mechanism, the initial flame kernel can be sufficiently grown at the time of cold engine having a low combustion speed, and the combustion can be stabilized.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0028]
FIG. 1 shows an embodiment of a start control device for an internal combustion engine according to the present invention. This activation control device includes a variable valve mechanism 101 for variably controlling the intake valve closing timing, and a compression ratio variable mechanism 102 for variably controlling the nominal compression ratio ε of the internal combustion engine.
[0029]
FIG. 2 is an explanatory diagram showing the configuration of the variable valve mechanism 101. The variable valve mechanism includes a lift / operating angle variable mechanism 1 that changes the lift / operating angle of the intake valve 12, and the lift. A phase variable mechanism 2 that advances or retards the phase of the central angle (phase relative to the crankshaft) is combined.
[0030]
First, the lift / operating angle variable mechanism 1 will be described with reference to the operation explanatory diagram of FIG. The lift / operating angle variable mechanism 1 has been previously proposed by the applicant of the present application. However, since it has been publicly known, for example, in Japanese Patent Application Laid-Open No. 11-107725, only the outline thereof will be described.
[0031]
The lift / operating angle variable mechanism 1 includes a hollow drive shaft 13 rotatably supported by a cam bracket (not shown) above the cylinder head 51, and an eccentric cam 15 fixed to the drive shaft 13 by press-fitting or the like. The control shaft 16 is rotatably supported above the drive shaft 13 by the same cam bracket and is disposed in parallel with the drive shaft 13 and is supported by the eccentric cam portion 17 of the control shaft 16 so as to be swingable. The rocker arm 18 and a swing cam 20 that abuts against a tappet 19 disposed at the upper end of each intake valve 12 are provided. The eccentric cam 15 and the rocker arm 18 are linked by a link arm 25, and the rocker arm 18 and the swing cam 20 are linked by a link member 26.
[0032]
As will be described later, the drive shaft 13 is driven by a crankshaft of an engine via a timing chain or a timing belt.
[0033]
The eccentric cam 15 has a circular outer peripheral surface, the center of the outer peripheral surface is offset from the shaft center of the drive shaft 13 by a predetermined amount, and the annular portion 25a of the link arm 25 is rotatable on the outer peripheral surface. Is fitted.
[0034]
The rocker arm 18 has a substantially central portion supported by the eccentric cam portion 17, and an extension portion 25 b of the link arm 25 is linked to one end portion of the rocker arm 18, and the link member 26 is connected to the other end portion. The upper end is linked. The eccentric cam portion 17 is eccentric from the axis of the control shaft 16, and accordingly, the rocking center of the rocker arm 18 changes according to the angular position of the control shaft 16.
[0035]
The rocking cam 20 is fitted to the outer periphery of the drive shaft 13 and is rotatably supported. A lower end portion of the link member 26 is linked to an end portion 20a extending to the side. On the lower surface of the swing cam 20, a base circle surface 24a that forms a concentric arc with the drive shaft 13, a cam surface 24b extending in a predetermined curve from the base circle surface 24a to the end portion 20a, Are formed continuously, and the base circle surface 24 a and the cam surface 24 b come into contact with the upper surface of the tappet 19 according to the swing position of the swing cam 20.
[0036]
That is, the base circle surface 24a is a section where the lift amount becomes 0 as a base circle section. As shown in FIG. 3, when the swing cam 20 swings and the cam surface 24b comes into contact with the tappet 19, gradually. It will lift to. A slight ramp section is provided between the base circle section and the lift section.
[0037]
As shown in FIGS. 1 and 2, the control shaft 16 is configured to rotate within a predetermined angle range by a lift / operation angle control hydraulic actuator 31 provided at one end. The hydraulic pressure supply to the lift / operating angle control hydraulic actuator 31 is controlled by the first hydraulic control unit 32 based on a control signal from the engine control unit 33.
[0038]
The operation of the variable lift / operating angle mechanism 1 will be described. When the drive shaft 13 rotates, the link arm 25 moves up and down by the cam action of the eccentric cam 15, and the rocker arm 18 swings accordingly. The swing of the rocker arm 18 is transmitted to the swing cam 20 via the link member 26, and the swing cam 20 swings. The tappet 19 is pressed by the cam action of the swing cam 20, and the intake valve 12 is lifted.
[0039]
Here, when the angle of the control shaft 16 changes via the lift / operating angle control hydraulic actuator 31, the initial position of the rocker arm 18 changes, and consequently, the initial swing position of the swing cam 20 changes.
[0040]
For example, if the eccentric cam portion 17 is positioned upward as shown in FIG. 3A, the rocker arm 18 is positioned upward as a whole, and the end portion 20a of the swing cam 20 is relatively lifted upward. It becomes a state. That is, the initial position of the swing cam 20 is inclined in the direction in which the cam surface 24 b is separated from the tappet 19. Therefore, when the swing cam 20 swings with the rotation of the drive shaft 13, the base circle surface 24a continues to contact the tappet 19 for a long time, and the period during which the cam surface 24b contacts the tappet 19 is short. Therefore, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.
[0041]
Conversely, if the eccentric cam portion 17 is positioned downward as shown in FIG. 3B, the rocker arm 18 is positioned downward as a whole, and the end portion 20a of the swing cam 20 is pushed downward relatively. It will be in the state. That is, the initial position of the swing cam 20 is inclined in the direction in which the cam surface 24 b approaches the tappet 19. Accordingly, when the swing cam 20 swings with the rotation of the drive shaft 13, the portion that contacts the tappet 19 immediately shifts from the base circle surface 24a to the cam surface 24b. Therefore, the lift amount is increased as a whole, and the operating angle is increased.
[0042]
Since the initial position of the eccentric cam portion 17 can be continuously changed, the valve lift characteristics change continuously as shown in FIG. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously. In this embodiment, the opening timing and closing timing of the intake valve 12 change substantially symmetrically as the lift and operating angle change.
[0043]
Next, as shown in FIG. 2, the phase variable mechanism 2 is configured so that the sprocket 35 provided at the front end of the drive shaft 13 and the sprocket 35 and the drive shaft 13 are relatively moved within a predetermined angle range. And a hydraulic actuator 36 for phase control that is rotated to the right. The sprocket 35 is linked to the crankshaft via a timing chain or timing belt (not shown). The hydraulic pressure supply to the phase control hydraulic actuator 36 is controlled by the second hydraulic pressure control unit 37 based on a control signal from the engine control unit 33.
By this hydraulic control to the phase control hydraulic actuator 36, the sprocket 35 and the drive shaft 13 rotate relatively, and the lift center angle is retarded as shown in FIG. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The phase variable mechanism 2 is not limited to a hydraulic one, and various configurations such as one using an electromagnetic actuator are possible.
[0044]
The lift / working angle variable mechanism 1 and the phase variable mechanism 2 may be controlled by providing a sensor for detecting an actual lift / working angle or phase and performing a closed loop control or depending on operating conditions. It is also possible to simply perform open loop control.
[0045]
FIG. 6 is a diagram illustrating a configuration of the variable compression ratio mechanism 102.
[0046]
The crankshaft 51 includes a plurality of journal portions 52 and a crankpin portion 53, and the journal portion 52 is rotatably supported by the main bearing of the cylinder block 50. The crankpin portion 53 is eccentric from the journal portion 52 by a predetermined amount, and a lower link 54 serving as a second link is rotatably connected thereto.
[0047]
The lower link 54 is configured to be split into two left and right members, and the crank pin portion 53 is fitted in a substantially central connecting hole.
[0048]
The upper link 55 serving as the first link has a lower end side rotatably connected to one end of the lower link 54 by a connecting pin 56, and an upper end side rotatably connected to a piston 58 by a piston pin 57. The piston 58 receives the combustion pressure and reciprocates in the cylinder 59 of the cylinder block 50. Note that the intake valve 12 and an exhaust valve (not shown) are disposed above the cylinder 59.
[0049]
The control link 60 serving as the third link is pivotally connected at its upper end side to the other end of the lower link 54 by a connecting pin 61, and the lower end side of the lower part of the cylinder block 50 that forms part of the engine body via the control shaft 62. It is connected to the pivotable. Specifically, the control shaft 62 is rotatably supported by the engine body and has an eccentric cam portion 62a that is eccentric from the center of rotation, and the lower end portion of the control link 60 is rotatable on the eccentric cam portion 62a. Is fitted.
[0050]
The rotational position of the control shaft 62 is controlled by a compression ratio control actuator 63 using an electric motor based on a control signal from the engine control unit 33 (see FIG. 1).
[0051]
In the variable compression ratio mechanism 102 using the multi-link type piston-crank mechanism as described above, when the control shaft 62 is rotated by the compression ratio control actuator 63, the center position of the eccentric cam portion 62a, in particular, the engine. The relative position with respect to the main body changes. Thereby, the rocking | fluctuation support position of the lower end of the control link 60 changes.
When the swing support position of the control link 60 changes, the stroke of the piston 58 changes, and the position of the piston 58 at the piston top dead center (TDC) becomes higher or lower as shown in FIG. This makes it possible to change the engine compression ratio. FIG. 8 representatively shows a high compression ratio state and a low compression ratio state, but the compression ratio can be continuously changed between them.
[0052]
Further, in the above-described multi-link variable compression ratio mechanism 102, a piston stroke characteristic close to simple vibration as shown in FIG. 7 can be obtained by appropriately selecting a link dimension. This stroke characteristic close to simple vibration is advantageous in terms of vibration noise, but in particular, the piston speed near the top dead center is about 20% slower than that of a general single link piston-crank mechanism. As described above, this is advantageous in the generation and growth of initial flame nuclei, particularly under conditions where the combustion rate is low, such as when cold.
[0053]
FIG. 9 shows the control characteristics of the compression ratio by the variable compression ratio mechanism 102. This compression ratio is a geometric compression ratio ε determined only by the change in the volume of the combustion chamber due to the stroke of the piston 58. In the present invention combined with the variable valve mechanism 101, the final actual compression ratio depends on the control of the intake valve closing timing. That is, substantial compression starts from the time when the intake valve 12 is closed, so that even if the nominal compression ratio ε is high, the actual compression ratio is lowered when the intake valve closing timing is earlier than the bottom dead center.
[0054]
FIG. 10 shows control of the intake valve closing timing by the variable valve mechanism 101 under typical operating conditions. Note that points (or regions) corresponding to the respective points are added to FIG. As shown in the figure, in (1) idling and (2) partial load range (R / L range), the lift operating angle Φ is advanced while the small operating angle is set. Therefore, the intake valve closing timing is also considerably faster than the bottom dead center. As a result, the pump loss can be greatly reduced.
Here, if the nominal compression ratio ε is at a normal level, the actual compression ratio is reduced and combustion is worsened. Therefore, as shown in FIG. 9, the compression ratio ε is increased in such a low load region. .
[0055]
(3) Since it is necessary to increase the intake charging efficiency in the acceleration region, the variable valve mechanism 101 is controlled so that the intake valve closing timing approaches the bottom dead center. For this reason, it is necessary to reduce the compression ratio ε in order to prevent the occurrence of knocking in advance. (4) (5) When fully open, to maximize the charging efficiency, the operating angle is sufficiently widened so that the intake valve opening timing is near top dead center and the intake valve closing timing is near bottom dead center And Accordingly, since the actual compression ratio tends to increase, the compression ratio ε by the variable compression ratio mechanism 102 is further reduced. Particularly in the severely knocking (4) low-speed full load region, it is necessary to bring the compression ratio ε close to a normal level. (5) In the high-speed full load range, the operating angle is further expanded, the central angle is delayed, and the closing timing is further delayed from the bottom dead center. At this high speed, knocking occurs. Since the combustion ends before the chemical reaction such as peroxide, which causes the above, proceeds, the compression ratio ε can be increased from a low speed. This also increases the expansion ratio, which is advantageous in that the exhaust temperature is lowered and deterioration of the catalyst provided in the exhaust system can be prevented.
[0056]
Thus, in the present embodiment, the operating angle and lift center angle of the intake valve 12 and the compression ratio are controlled based on the control map prepared in advance. As shown in FIG. 1, in this embodiment, a knocking sensor 71 for detecting the occurrence of knocking is provided in the cylinder block 50 and the like, and the compression ratio ε and the like are also corrected by this knocking. Yes. Reference numeral 72 denotes an ignition advance control device.
[0057]
Next, control at startup will be described.
[0058]
The time chart of FIG. 11 shows the situation from the start of cranking by the starter motor until the engine shifts to a self-sustained operation after the first explosion in the cold state.
In this embodiment, the compression ratio ε is maintained at a state immediately before the engine is stopped. Normally, the idling operation is first performed and then the key is turned off. The ratio is set. Similarly, the operating angle of the intake valve 12 is set at the time of idling, and is kept close to the minimum operating angle. The intake valve closing timing (IVC) is advanced before the bottom dead center at the start of cranking, and the actual compression ratio is considerably lower than the maximum value. For this reason, at the start of cranking, a so-called decompression effect that avoids excessive compression is obtained, and the cranking speed rapidly increases to a predetermined speed. If the cranking speed is too low, even if fuel injection is performed and ignition is not performed, the first explosion does not occur. Thus, priority is given to increasing the cranking speed rather than the actual compression ratio.
[0059]
When the cranking rotational speed reaches a value greater than or equal to a predetermined value, the lift center angle φ of the intake valve 12 is retarded. Accordingly, the intake valve closing timing approaches the bottom dead center, and the actual compression ratio increases. At the same time, the intake valve opening timing (IVO) is delayed from the top dead center. As a result, when negative pressure develops in the first half of the intake stroke and the intake valve 12 starts to open with a small lift, the intake valve opens at the speed of sound. Since fuel and air are inhaled, it is extremely advantageous for air-fuel mixture formation, and fuel atomization and vaporization are promoted. Moreover, since such flow velocity energy is finally converted into thermal energy, there is also an effect of raising the intake air temperature.
[0060]
Since the geometric compression ratio ε is originally high, the mixture temperature at the compression top dead center rises to a sufficient temperature due to the increase in the actual compression ratio, leading to the first explosion. In order to maintain stable combustion even after the first explosion, it is preferable to maintain such a high compression ratio state.
[0061]
Next, the time chart of FIG. 12 shows the control at the time of start-up when the engine is suddenly stopped under conditions where the compression ratio ε is not high, such as other than idling, and left to stand until the next morning, and then the cold engine is started. ing. There are various initial conditions in this case, but the basic concept of control is the same as the example described above. In this illustrated example, since the compression ratio is low when the key is ON, the low compression ratio is maintained at the initial stage of cranking, and the increase in the cranking rotation speed is promoted. Then, when the cranking rotational speed becomes equal to or higher than a predetermined value, the state shifts to the high compression ratio state. At the same time, the lift center angle Φ is retarded and the intake valve closing timing is brought close to the bottom dead center. As a result, similar to the above-described example, it is possible to start up well. In the example of FIG. 12, the amount of retardation of the lift center angle Φ is small because the intake valve operating angle EA is larger than that of the example of FIG. 11, so that the intake valve closing timing is brought close to the bottom dead center. This is because the required amount of retardation is small.
[0062]
FIG. 13 is a flowchart showing a flow of control at the time of startup described above. First, when the ignition key is turned on (step 1) and the cooling water temperature is equal to or higher than the predetermined temperature (step 2), the process proceeds to another warm-up control (step 3). If it is in the cold state, the process proceeds to step 4 to read the control maps of the compression ratio ε, the operating angle EA, and the lift center angle Φ in the cold state. Then, in step 5, the actual state of the compression ratio ε at that time is determined. If the compression ratio is in the high compression ratio state, the process proceeds to step 6 and thereafter, and the control corresponding to FIG. On the other hand, if the compression ratio state is low, the process proceeds to step 11 and the subsequent steps, and the control corresponding to FIG.
[0063]
That is, in the high compression ratio state, the lift / working angle variable mechanism 1 is controlled so that the working angle EA becomes the target value after waiting until the cranking rotational speed reaches the predetermined rotational speed (step 6). (Steps 7 and 8). At the same time, the phase variable mechanism 2 is controlled so that the lift center angle Φ becomes the target value (steps 9 and 10).
[0064]
In the case of the low compression ratio state, after waiting until the cranking rotational speed reaches the predetermined rotational speed (step 11), the lift / operating angle variable mechanism 1 is controlled so that the operating angle EA becomes the target value ( Together with steps 12 and 13, the phase variable mechanism 2 is controlled so that the lift center angle Φ becomes the target value (steps 14 and 15). At the same time, control of the compression ratio ε is started, and the compression ratio mechanism 102 is controlled so that the compression ratio ε becomes a target value (steps 16 and 17).
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the entire system of an activation control apparatus according to the present invention.
FIG. 2 is a perspective view showing a variable valve mechanism in this embodiment.
FIG. 3 is an operation explanatory diagram of a lift / operating angle variable mechanism.
FIG. 4 is a characteristic diagram showing changes in lift / operating angle characteristics by a lift / operating angle variable mechanism;
FIG. 5 is a characteristic diagram showing a phase change of a valve lift characteristic by a phase variable mechanism.
FIG. 6 is a front view showing a variable compression ratio mechanism in this embodiment.
FIG. 7 is a characteristic diagram showing piston stroke characteristics of a multi-link type piston-crank mechanism serving as a variable compression ratio mechanism.
FIG. 8 is an operation explanatory diagram of a variable compression ratio mechanism.
FIG. 9 is a characteristic diagram showing compression ratio control characteristics.
FIG. 10 is a characteristic diagram showing valve lift characteristics under typical operating conditions.
FIG. 11 is a time chart showing the operation of each part at the time of cold start from a high compression ratio state.
FIG. 12 is a time chart showing the operation of each part at the time of cold start from a low compression ratio state.
FIG. 13 is a flowchart showing a flow of control at startup.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Variable valve mechanism 102 ... Variable compression ratio mechanism 1 ... Lift / operation angle variable mechanism 2 ... Phase variable mechanism

Claims (10)

Variable valve means for variably controlling the closing timing of the intake valve of the internal combustion engine, which is a gasoline engine, and variable control of the nominal compression ratio of the internal combustion engine by changing the piston position so that the nominal compression ratio decreases as the load increases. In the internal combustion engine having the compression ratio control means, the initial value of cranking is controlled by the variable valve mechanism while the nominal compression ratio is maintained at a high compression ratio equivalent to that at idling by the compression ratio control means when the engine is started. An internal combustion engine start control device characterized in that the intake valve closing timing is set to a timing away from bottom dead center, and the intake valve closing timing is brought close to bottom dead center after cranking is started. If the initial position of the compression ratio control means before the start of cranking is in a nominal compression ratio state lower than the nominal compression ratio corresponding to the idling , cranking is started with the low nominal compression ratio state, and the cranking is started. 2. The internal combustion engine according to claim 1, wherein after the start of ranking, the compression ratio control means is controlled to increase the nominal compression ratio at the same time as the intake valve closing timing approaches the bottom dead center. Start control device.   The compression ratio control means comprises a multi-link type piston-crank mechanism, and is configured such that the reciprocating motion of the piston with respect to the rotation of the crankshaft has a stroke characteristic close to a single vibration motion. An activation control device for an internal combustion engine according to 1 or 2. The variable valve means includes a variable lift / operating angle mechanism that can simultaneously and continuously increase and decrease the lift / operating angle of the intake valve, and when the engine is cold start, The start control device for an internal combustion engine according to any one of claims 1 to 3, wherein the start / control angle is controlled to a small lift / operating angle corresponding to idling . The variable valve mechanism includes a phase variable mechanism that delays the phase of the lift center angle of the intake valve, and after the cranking starts, the intake valve closing timing approaches a bottom dead center from a position before the bottom dead center . The start control device for an internal combustion engine according to any one of claims 1 to 4, wherein the lift center angle is retarded as described above.   The variable valve means includes both a lift / operating angle variable mechanism that can simultaneously and continuously expand and contract the lift / operating angle of the intake valve, and the phase variable mechanism. The start control device for an internal combustion engine according to claim 5, wherein the retard angle of the lift center angle is increased under the condition that the lift / operating angle is small.   The compression ratio control means includes a first link coupled to the piston via a piston pin, and a first link coupled to the first link so as to be swingable and rotatably coupled to a crankpin portion of the crankshaft. 7. The system according to claim 1, further comprising a second link and a third link that is swingably connected to the second link and that is swingably supported by the engine body. A startup control device for an internal combustion engine according to claim 1.   8. The start control device for an internal combustion engine according to claim 7, wherein the compression ratio is variably controlled by changing a fulcrum position of the third link with respect to the engine main body according to engine operating conditions.   The variable lift / operating angle mechanism includes an eccentric cam that is rotationally driven by a drive shaft, a link arm that is rotatably fitted to the outer periphery of the eccentric cam, and an eccentric cam portion that is provided in parallel with the drive shaft. A pivotable control shaft comprising: a rocker arm that is rotatably mounted on an eccentric cam portion of the control shaft and is pivoted by the link arm; and is rotatably supported by the drive shaft, and A rocking cam connected to the rocker arm via a link, and rocking with the rocker arm to press the tappet of the intake valve, thereby changing the rotational position of the eccentric cam portion of the control shaft. The startup control device for an internal combustion engine according to claim 4 or 6, wherein the lift / operating angle of the intake valve is increased or decreased simultaneously.   The phase variable mechanism changes a phase of a cam sprocket that is rotationally driven by the crankshaft via a chain or a timing belt, a camshaft that is rotationally driven by the cam sprocket, and the cam sprocket and the camshaft. The start control device for an internal combustion engine according to claim 5 or 6, wherein the start control device includes a mechanism.

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