JP4649714B2 - Control device for internal combustion engine for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine for a vehicle suitable for an internal combustion engine that repeatedly stops and starts automatically during vehicle operation, such as a so-called hybrid vehicle and an automobile equipped with idle stop means. The present invention relates to variable control of an intake valve suitable for a kind of internal combustion engine.
[0002]
[Prior art]
Various types of hybrid vehicles have been proposed in the past, in which the vehicle is driven by an internal combustion engine during acceleration and high-speed travel, and the motor is driven during low-speed travel, and the internal combustion engine is stopped during low-speed travel or when the vehicle is stopped. Has been. In general, this type of hybrid vehicle has a configuration in which a motor for driving a vehicle and a motor for starting an internal combustion engine as necessary are individually provided. When the vehicle starts slowly, the running motor starts running. After that, when the required torque reaches the limit of the running motor due to an increase in the vehicle speed, etc., the internal combustion engine is automatically started by the starting motor. It has become. Usually, both or one of these motors is also used for power generation, and even during low-speed operation, when the battery charge decreases, the internal combustion engine is started and charging is performed. Done.
[0003]
Also, For travel Even in a vehicle that is driven only by an internal combustion engine without having a motor, the vehicle is provided with a so-called idle stop means that is automatically stopped when the vehicle is stopped and that is automatically started when the vehicle starts. Are known.
[0004]
As control of an intake valve suitable for an internal combustion engine in which such automatic stop and start are repeated, for example, Japanese Patent Laid-Open No. 2000-34913 discloses that the closing timing is greatly increased while maximizing the operating angle of the intake valve at the time of startup. By delaying, it is disclosed that the compression pressure is sufficiently suppressed as a so-called decompression action, and unpleasant vehicle body vibration is suppressed.
[0005]
Japanese Laid-Open Patent Publication No. 2000-73901 proposes reducing the pump loss by a so-called Atkinson cycle in which the closing timing of the intake valve is set later and the expansion ratio is larger than the actual compression ratio.
[0006]
The present applicant has previously proposed a variable valve mechanism that can continuously increase and decrease the lift and operating angle of the intake valve (for example, Japanese Patent Laid-Open Nos. 11-107725 and 11-11). 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 delays the phase of the center angle of the lift.
[0007]
[Problems to be solved by the invention]
In order to improve the thermal efficiency of the internal combustion engine, it is an important factor to stop the internal combustion engine when the vehicle is stopped or when the motor is running in a hybrid vehicle. However, when the internal combustion engine is started in a stopped state or in a state where the motor is running smoothly, a mount vibration due to compression is generated until the rotational speed increases, and this is not a vehicle body vibration. There is a problem of giving pleasure.
[0008]
In order to avoid this, it is necessary to keep the compression pressure sufficiently low by greatly delaying the closing timing of the intake valve until it passes through the resonance point of the mount, as disclosed in Japanese Patent Laid-Open No. 2000-34913. It is effective.
[0009]
Further, in a hybrid vehicle, it is indispensable to improve the fuel efficiency that the internal combustion engine is operated under high-efficiency conditions when charging the battery after running the motor. As shown in Japanese Patent No. 73901, it can be said that reducing the pump loss by setting the closing timing of the intake valve later and setting the expansion ratio larger than the actual compression ratio is an effective means. In particular, it is reasonable in that it can be directly applied to vibration reduction at the time of engine restart as described above.
[0010]
However, under these conditions, the actual compression ratio is significantly reduced under conditions where the closing timing of the intake valve is greatly delayed. Therefore, when the internal combustion engine is started, it is preferable that motoring is not performed to a considerably high speed. The first explosion cannot be obtained. This is not a major problem under conditions where there is sufficient time in terms of combustion, such as restarting during slow acceleration after warm-up, but at low temperatures, the capacity of the battery is reduced, so high rotation speed There is a limit to motoring, especially under conditions that demand responsiveness, such as when starting suddenly. It was.
[0011]
The present invention has been made paying attention to such problems, and by optimizing the lift valve operating angle and the phase of the central angle of the intake valve, the compression at the start-up is reduced and the motoring rotational speed is reduced. The aim is to achieve both good start-up performance that leads to the first explosion without significant increase.
[0012]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a lift / working angle variable mechanism capable of simultaneously and continuously expanding and reducing the lift / working angle of the intake valve, and a phase variable for delaying the phase of the center angle of the lift of the intake valve. A mechanism, means for detecting the rotational speed and load of the internal combustion engine, control means for controlling the lift / operating angle and central angle of the intake valve in accordance with the engine rotational speed and load, and the internal combustion engine Cranking Do For startup A motor, and configured to stop the ignition operation of the internal combustion engine when the vehicle is stopped and to restart the ignition operation by starting the internal combustion engine with the motor when the vehicle starts, By the internal combustion engine In a control device for an internal combustion engine for a vehicle in which the intake valve closing timing is controlled before bottom dead center by the lift / operating angle variable mechanism and the phase variable mechanism during R / L traveling,
Immediately before the internal combustion engine is stopped when the vehicle stops, the lift / operating angle of the intake valve is By the internal combustion engine While controlling to be smaller than the lift / operation angle during R / L traveling, the central angle of the intake valve is By the internal combustion engine The intake valve closing timing is controlled before the bottom dead center by controlling the leading angle from the center angle during R / L driving. By the internal combustion engine It is characterized by being on the advance side with respect to the closing timing during R / L traveling.
[0013]
This is provided with so-called idle stop means for stopping the internal combustion engine when the vehicle is stopped, and the internal combustion engine is automatically started when the vehicle starts.
[0014]
The lift / operating angle variable mechanism is configured such that when the operating angle is increased, the lift is simultaneously increased, and conversely, when the operating angle is reduced, the lift is simultaneously decreased. If the lift / operating angle is reduced to a predetermined value or less immediately before the stop, cranking by the motor is started with the lift / operating angle being small when starting up thereafter. At the same time, since the center angle of the lift is controlled to the advance side, the intake valve closing timing is a position that is greatly advanced from the bottom dead center. Therefore, the compression pressure is reduced, and unpleasant vibration during cranking is avoided by the so-called decompression action. In addition, since the lift of the intake valve during the intake stroke of the piston is small, the flow rate of the intake air passing through the intake valve becomes very high, the combustion speed after ignition is sufficiently high, and a good initial explosion is obtained. It is done. In other words, if the actual compression ratio is set to be the same as compared with the case where the operating angle is expanded and the intake valve closing timing is greatly delayed after bottom dead center, the lift / operating angle is as shown in the present invention. When the intake valve closing timing is advanced while reducing the pressure, the in-cylinder gas flow becomes more active, and a reliable initial explosion can be obtained at a lower speed.
[0015]
According to a second aspect of the present invention, there is provided a lift / working angle variable mechanism capable of simultaneously and continuously expanding and reducing the lift / working angle of the intake valve and a phase variable for delaying the phase of the center angle of the lift of the intake valve. A mechanism, means for detecting the rotational speed and load of the internal combustion engine, control means for controlling the lift / operating angle and central angle of the intake valve in accordance with the engine rotational speed and load, and rotationally driving the internal combustion engine A motor and a second motor capable of driving the vehicle, the ignition operation of the internal combustion engine is stopped when the vehicle is stopped and the vehicle is traveling at a low speed, and the vehicle is driven by the second motor. The motor is configured to start the internal combustion engine and restart the ignition operation. , R / L When traveling In the control device for an internal combustion engine for a vehicle in which the intake valve closing timing is controlled before bottom dead center by the lift / operating angle variable mechanism and the phase variable mechanism,
Immediately before the internal combustion engine stops due to vehicle operating conditions, the intake valve lift and operating angle are Using engine generated torque R / L When traveling And control the center angle of the intake valve, Using engine generated torque R / L When traveling The intake valve closing timing is set to the position before the bottom dead center. Using engine generated torque R / L When traveling It is characterized by being on the advance side of the closing time of.
[0016]
This is applied to a so-called hybrid-type vehicle, and as in the first aspect described above, a decompression action can be obtained at the time of start-up, and at the same time, a reliable initial explosion can be obtained by activating in-cylinder gas flow.
[0017]
According to a third aspect of the present invention, in the control device for an internal combustion engine for a vehicle according to the first or second aspect, in the case of a sudden start from a vehicle stop state, As above Cranking of internal combustion engine by lift and operating angle When Fuel injection and ignition After starting Further, the present invention is characterized in that the intake valve closing timing is controlled to approach the bottom dead center by delaying the central angle of the intake valve.
[0018]
According to a fourth aspect of the present invention, in the control apparatus for an internal combustion engine for a vehicle according to the second aspect, in the case of rapid acceleration from the motor running by the second motor, As above Cranking of internal combustion engine by lift and operating angle When Fuel injection and ignition After starting Further, the present invention is characterized in that the intake valve closing timing is controlled to approach the bottom dead center by delaying the central angle of the intake valve.
[0019]
In these third and fourth aspects, the decompression action is obtained at the initial stage of cranking, and then the intake valve closing timing approaches the bottom dead center, so that the actual compression ratio quickly increases. As a result, the torque of the internal combustion engine quickly increases.
[0020]
According to a fifth aspect of the present invention, in the control device for an internal combustion engine for a vehicle according to the first or second aspect, when the vehicle starts slowly from a stopped state, As above After starting cranking of the internal combustion engine at the lift / operating angle, fuel injection and ignition are started when the predetermined rotational speed is reached, and the central angle of the intake valve corresponds to the engine load and rotational speed Control is made to a predetermined advance position.
[0021]
According to a sixth aspect of the present invention, in the control device for an internal combustion engine for a vehicle according to the second aspect, in the slow acceleration from the motor running by the second motor, As above After starting cranking of the internal combustion engine at the lift / operating angle, fuel injection and ignition are started when the predetermined rotational speed is reached, and the central angle of the intake valve corresponds to the engine load and rotational speed Control is made to a predetermined advance position.
[0022]
In these fifth and sixth aspects, the actual compression ratio becomes low and the decompression action is obtained from the time cranking is started until the predetermined rotational speed is reached. The predetermined rotational speed is preferably set to a value that passes the vicinity of 300 to 400 rpm, which is the resonance point of the engine mount that supports the internal combustion engine, for example. In this way, unpleasant vibration can be reliably prevented by the decompression action.
[0024]
The lift / operating angle variable mechanism is, for example, a claim 7 As described above, an eccentric cam that is rotationally driven by a drive shaft, a link arm that is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, and a rotation that is provided in parallel to the drive shaft and includes an eccentric cam portion A control shaft that can be rotated, a rocker arm that is rotatably mounted on an eccentric cam portion of the control shaft, and is swingably supported by the link arm, and is rotatably supported by the drive shaft, and is connected to the rocker arm via a link. And a swing cam that presses the tappet of the intake valve by swinging with the rocker arm, and by changing the rotational position of the eccentric cam portion of the control shaft, The lift and operating angle are configured to increase and decrease simultaneously.
[0025]
The phase variable mechanism is, for example, a claim 8 The sprocket is arranged concentrically with the drive shaft and driven by the crankshaft via a chain or timing belt, and is mounted between the sprocket and the drive shaft so that the relative And means for changing the phase.
[0026]
【The invention's effect】
According to the control apparatus for an internal combustion engine for a vehicle according to the present invention, in a vehicle internal combustion engine that is automatically stopped and restarted, such as a hybrid type automobile or an automobile equipped with idle stop means, a so-called decompression unit is started up. As a result, an unpleasant vibration can be avoided, and the activation of the in-cylinder gas flow leads to the first explosion at a low rotational speed, thus ensuring good starting performance.
[0027]
In particular, according to the third and fourth aspects of the invention, the torque can be increased by quickly starting up while obtaining the decompression effect, and the starting and acceleration performance is excellent.
[0028]
According to the fifth and sixth aspects of the present invention, the decompression operation is reliably continued until the engine speed exceeds the resonance point of the engine mount, so that unpleasant vibration can be prevented more reliably.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a hybrid vehicle will be described.
[0030]
FIG. 1 is a configuration explanatory view showing the configuration of an intake valve side variable valve mechanism of an internal combustion engine. The variable valve mechanism includes a lift / working angle variable mechanism 1 that changes a lift / working angle of an intake valve; A phase variable mechanism 2 that advances or retards the phase of the center angle of the lift (phase with respect to a crankshaft (not shown)) is combined.
[0031]
FIG. 2 shows only the lift / operating angle variable mechanism 1, and the lift / operating angle variable mechanism 1 will be described with reference to FIGS. 1 and 2. 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.
[0032]
The variable lift / operating angle mechanism 1 has a hollow shape rotatably supported by an intake valve 12 slidably provided on a cylinder head 11 via a valve guide (not shown) and a cam bracket 14 above the cylinder head 11. Drive shaft 13, an eccentric cam 15 fixed to the drive shaft 13 by press-fitting or the like, and a cam bracket 14 that is rotatably supported above the drive shaft 13 and arranged in parallel with the drive shaft 13. The control shaft 16, the rocker arm 18 that is swingably supported by the eccentric cam portion 17 of the control shaft 16, and the swing cam 20 that contacts the tappet 19 disposed at the upper end of each intake valve 12. It has. 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.
[0033]
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.
[0034]
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.
[0035]
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.
[0036]
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, and a cam surface 24b extending in a predetermined curve from the base circle surface 24a to the end portion 20a, The base circle surface 24a and the cam surface 24b are in contact with the upper surface of the tappet 19 according to the swing position of the swing cam 20.
[0037]
That is, the base circle surface 24a is a section where the lift amount becomes 0 as a base circle section, and when the swing cam 20 swings and the cam surface 24b contacts the tappet 19, it gradually lifts. Become. A slight ramp section is provided between the base circle section and the lift section.
[0038]
As shown in FIG. 1, the control shaft 16 is configured to rotate within a predetermined rotation 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.
[0039]
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.
[0040]
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.
[0041]
For example, if the eccentric cam portion 17 is positioned upward in the figure, the rocker arm 18 is positioned upward as a whole, and the end 20a of the swing cam 20 is relatively lifted upward. 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.
[0042]
Conversely, if the eccentric cam portion 17 is positioned downward in the figure, the rocker arm 18 is positioned downward as a whole, and the end portion 20a of the swing cam 20 is pushed downward relatively. 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.
[0043]
Since the position of the eccentric cam portion 17 can be continuously changed, the valve lift characteristic changes continuously as shown in FIG. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously. In particular, in this case, the opening timing and closing timing of the intake valve 12 change substantially symmetrically as the lift and operating angle change.
[0044]
Next, as shown in FIG. 1, 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 the hydraulic pressure 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.
[0045]
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.
[0046]
Next, the configuration of the drive system of the hybrid vehicle will be described with reference to FIG. In the figure, reference numeral 51 denotes an internal combustion engine provided with the variable valve mechanism described above, and an activation motor 52 that also serves as a generator is always linked to one end of the crankshaft. The other end of the crankshaft is connected to an input shaft 54 of a belt type continuously variable transmission 53 via an electromagnetic clutch 55. A travel motor 56 is integrally attached to the input shaft 54. The traveling motor 56 can generate power by regeneration. The continuously variable transmission 53 includes a final reduction gear 57 and drives the drive wheels 58. Further, in order to supply hydraulic pressure to the continuously variable transmission 53, a hydraulic pump 59 driven by an auxiliary motor 58 is provided. These three motors 52, 56, and 58 are controlled via the inverter 61 by the power of the battery 60.
[0047]
FIG. 6 shows the operation of each part from vehicle start to acceleration, which is a typical operation of the hybrid vehicle. In addition, the arrow in a figure represents the flow of energy. When the vehicle is stopped, the internal combustion engine 51 is normally stopped except when the load on the auxiliary machine or the like is large or when the battery 60 needs to be charged. As shown, the traveling motor 56 drives the continuously variable transmission 53 by the battery 60 and starts at an optimum gear ratio. Note that the electromagnetic clutch 55 is disengaged during the motor travel. Thereafter, if the battery power supply is sufficient, the low-speed driving continues in principle as long as the battery power is sufficient. However, when the vehicle reaches a predetermined vehicle speed or shifts to acceleration, as shown in FIG. The internal combustion engine 51 is activated by the activation motor 52 during the traveling of the vehicle. Then, the rotations are quickly synchronized, and the electromagnetic clutch 55 is connected as shown in FIG. The torque generated by the traveling motor 56 decreases in accordance with the torque generation of the internal combustion engine 51, and the transition to engine traveling is possible without torque shock.
[0048]
As described above, in a hybrid vehicle, since there are motor travel and engine travel, it is necessary to generate electric power for motor travel as a role of the internal combustion engine 51. This electric power can also be obtained by regenerative power generation by the traveling motor 56 at the time of deceleration. However, this is not enough, and most of the electric power is generated by the generated electric power obtained by driving the internal combustion engine 51 with the starting motor 52. Therefore, when the internal combustion engine 51 is started after the motor travels, the electric power consumed by the motor travel is generated first. Therefore, the load of the internal combustion engine 51 is a normal road steady travel (R / L travel). , Get quite big. In general, the thermal efficiency of an internal combustion engine increases as the load increases. Therefore, generating a driving force necessary for power generation and traveling in such a relatively high load region has a great effect on improving the efficiency of the entire engine. There are three major factors for improving the thermal efficiency of hybrid vehicles, as well as idling stop and regeneration.
[0049]
It is also important that when the internal combustion engine 51 is started, the vibration is reduced by the decompression action, and then when switching to such power generation running, the opening / closing timing of the intake valve is continuously connected with a minimum change. Further, since the internal combustion engine 51 is often immediately stopped at the time of low speed deceleration, control with high responsiveness becomes unnecessary if a sufficient decompression action is obtained with the intake valve opening / closing timing at the time of power generation for charging.
[0050]
Next, FIG. 7 shows the control characteristics of the intake valve opening / closing timing before and after starting from slow acceleration, which is a typical engine starting pattern in such a hybrid vehicle.
・ When the engine is stopped
In preparation for the next restart, as shown in (1), the intake valve closing timing (IVC) is set to be lower than the bottom dead center with a small lift / small operating angle and the center angle Φ of the lift near the top dead center. The time will be significantly earlier.
・ At startup
As shown in (2), cranking by the starting motor 52 starts with the timing setting at the time of engine stop of (1) above. In this characteristic, since IVC is in the middle of the intake stroke, the compression pressure is reduced, and unpleasant vibrations associated with cranking are suppressed. Here, for example, when a large lift and a large operating angle are set at the time of startup as in the prior art, the decompression is performed with the IVC greatly delayed from the bottom dead center. However, in the present invention, the IVC is lowered. The intake valve is closed in the middle of the intake stroke so as to proceed substantially beyond the dead center so that substantially the same decompression action is obtained. In this method, when the piston is stopped at the bottom dead center, full compression is applied, so the decompression effect is lost.However, when the engine is stopped normally, the piston is pushed back by dynamic balance (compressed by compression). It is almost impossible to stop near the center of the stroke, and it is unlikely to stop at the bottom dead center. For further perfection, it is possible to stop the piston at a desired position by controlling the starting motor 52 when the engine is stopped.
・ Ignition and first explosion
In the case of slow acceleration, motoring is performed without fuel injection and ignition until the engine speed exceeds the mount resonance point. Fuel injection and ignition are started when the mount resonance point is passed. Here, as a characteristic of the intake valve, after exceeding the mount resonance point, the lift / operating angle is slightly increased as shown in (3) in order to increase the actual compression ratio. Even in this case, since the flow rate of the intake air passing through the intake valve is extremely high, the combustion speed after ignition is sufficiently high, and a good initial explosion can be obtained. For reference, FIG. 8 shows the effect of gas flow enhancement obtained by small lift control. In the case of the standard lift (1/1 lift), since the intake amount is small at low speed, the tumble ratio, which is a guideline for in-cylinder gas flow, is significantly reduced. However, the tumble ratio can be maintained at the same level as during high rotation by performing small lift control such as 1/5 lift or 1/10 lift. Since the mount resonance point is usually in the rotation range of 3 to 400 rpm, a tumble ratio equal to or higher than that of the standard lift high rotation can be obtained at any time in the region beyond this range in the case of a small lift. Therefore, compared with the prior art in which IVC is delayed by a large lift and a large operating angle as indicated by broken line IVC in FIG. A reliable first explosion is possible at low rotation.
・ R / L driving (power generation)
In the case of slow acceleration, after the internal combustion engine 51 is started, the engine travels immediately. However, immediately after the motor travels, it is necessary to generate power for charging the battery (power generation by the starter motor 52). The engine 51 is operated in a relatively high load state. Under this condition, the characteristics of the intake valve are as shown in (4), the valve overlap is large, an appropriate amount of residual gas is left in the cylinder, and IVC is also advanced from the bottom dead center. This is a setting aimed at reducing pump loss and is excellent in fuel efficiency. The transition from the first explosion to this setting is sufficient in a short time, and a smooth transition is possible. Further, when the speed is reduced from this condition, the internal combustion engine 51 is often stopped, but it is easy to control the actuators 31 and 36 to the state {circle around (1)} before the internal combustion engine 51 is completely stopped. . In addition, even if it stops at the timing (4) due to a delay in control, a considerable decompression effect can be obtained.
・ Fully open
In the case of full open acceleration without a power generation load, the characteristic is controlled to (5). This further expands the operating angle in order to secure the intake air amount, and IVC is set at around the bottom dead center. Since this setting is also an extension of (4), it is advantageous in terms of control responsiveness.
[0051]
Next, FIG. 9 shows the transient control characteristics of each functional element during slow acceleration. In the figure, the traveling motor 56 is abbreviated as “motor A”, and the starting motor 52 is abbreviated as “motor B”. As shown in the drawing, when the load on the traveling motor 56 increases during motor traveling, the internal combustion engine 51 is activated by the activation motor 52 in order to shift to engine traveling. At this time, the characteristics of the intake valve are controlled as described above, and activation is performed in the decompressed state. At the time of starting, the starting motor 52 functions as a starter, but after the internal combustion engine 51 is started, it is driven reversely as a generator. As the vehicle speed further increases, the amount of power generation gradually decreases, and a larger proportion of the engine-generated torque is supplied to the vehicle. Further, at the time of full opening acceleration, the driving motor 56 can assist, and the corresponding motor torque is added to the engine generated torque. The lift / operating angle of the intake valve is set to gradually increase as the intake amount increases (engine speed increases, load increases).
[0052]
Next, FIG. 10 shows the case of rapid acceleration from motor travel. In this case, fuel injection and ignition are started simultaneously with the start of cranking by the starting motor 52, and ignition and initial explosion are performed as early as possible. At the same time, the lift / operating angle is rapidly increased to shift to an intake valve opening / closing characteristic capable of ensuring the maximum torque as an internal combustion engine. In such a case, the motor assist is extremely effective, and a good acceleration feeling can be obtained.
[0053]
FIG. 11 shows a flowchart of intake valve opening / closing timing control at the time of acceleration, and this will be described along the flow. First, in step 1, operating conditions such as engine speed and throttle opening are detected. Then, when the vehicle is in a stopped state, the process proceeds to step 2 and subsequent steps. In step 2, acceleration is detected. If acceleration is detected, it is further determined in step 3 whether sudden acceleration is slow acceleration. If it is a slow acceleration, it will progress to step 4 and will start with a motor (traveling motor 56). On the other hand, if it is sudden acceleration, the routine proceeds to step 5 where the internal combustion engine 51 is activated by the activation motor 52. At the same time, control of the actuators 31 and 36 is started (step 6), and the opening timing (IVO), closing timing (IVC) and center angle of the intake valve are controlled to target values (step 7). Then, ignition is started when the engine speed reaches a predetermined value (step 8) (step 9), and when the engine speed reaches a predetermined value (step 10) or more, the electromagnetic clutch 55 is connected (step). 11). In the case of rapid acceleration, as described above, fuel injection and ignition may be started immediately without waiting until the predetermined rotational speed is reached in step 8.
[0054]
On the other hand, if the vehicle is traveling in R / L, acceleration is detected in step 12, and if acceleration is detected, it is further determined in step 13 whether it is sudden acceleration or slow acceleration. If it is slow acceleration, the process proceeds to step 14 and the control map for slow acceleration is read. If it is sudden acceleration, the process proceeds to step 15 and the control map for sudden acceleration is read. In step 16, the internal combustion engine 51 is activated by the activation motor 52. At the same time, control of the actuators 31 and 36 is started (step 17), and the opening timing (IVO), closing timing (IVC) and center angle of the intake valve are controlled to target values (step 18). Then, ignition is started when the engine speed reaches a predetermined value (step 19) (step 20), and when the engine speed reaches a predetermined value (step 21) or more, the electromagnetic clutch 55 is connected (step). 22). In the case of rapid acceleration, as described above, fuel injection and ignition may be started immediately without waiting until the predetermined rotational speed is reached in step 19.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism of an intake valve used in a control device for an internal combustion engine according to the present invention.
FIG. 2 is a cross-sectional view showing a lift / operating angle variable mechanism.
FIG. 3 is a characteristic diagram showing changes in lift / operating angle characteristics by a variable lift / operating angle mechanism;
FIG. 4 is a characteristic diagram showing a phase change of a valve lift characteristic by a phase variable mechanism.
FIG. 5 is an explanatory diagram showing a basic configuration of a hybrid vehicle.
FIG. 6 is an explanatory diagram showing the basic operation of this hybrid vehicle.
FIG. 7 is a characteristic diagram showing a change in opening / closing characteristics of the intake valve accompanying slow acceleration from a stopped state.
FIG. 8 is a characteristic diagram showing the enhancement of gas flow accompanying a small lift.
FIG. 9 is a timing chart showing the operation of each part during slow acceleration from motor travel.
FIG. 10 is a timing chart showing the operation of each part during rapid acceleration from motor travel.
FIG. 11 is a flowchart of the opening / closing timing control of the intake valve.
[Explanation of symbols]
1 ... Lift / operating angle variable mechanism
2 ... Phase variable mechanism
13 ... Drive shaft
15 ... Eccentric cam
16 ... Control axis
17 ... Eccentric cam
18 ... Rocker arm
25 ... Link arm
26 ... Link member
31 ... Hydraulic actuator for lift / operating angle control
33 ... Engine control unit
36 ... Hydraulic actuator for phase control

Claims (8)

A variable lift / operating angle mechanism that can simultaneously and continuously expand and contract the lift / operating angle of the intake valve, a variable phase mechanism that delays the phase of the central angle of the lift of the intake valve, and the rotational speed of the internal combustion engine And means for detecting the load, control means for controlling the lift / operating angle and central angle of the intake valve according to the engine speed and load, and a starting motor for cranking the internal combustion engine, The ignition operation of the internal combustion engine is stopped when the vehicle is stopped, the internal combustion engine is started by the motor when the vehicle starts, and the ignition operation is restarted, and the lift / operation angle during the R / L traveling by the internal combustion engine In a control device for an internal combustion engine for a vehicle in which the intake valve closing timing is controlled before bottom dead center by the variable mechanism and the phase variable mechanism,
Immediately before the stop of the internal combustion engine accompanying the vehicle stop, the lift / operation angle of the intake valve is controlled to be smaller than the lift / operation angle at the time of R / L traveling by the internal combustion engine , and the central angle of the intake valve is The intake valve closing timing is controlled before the bottom dead center and is advanced from the closing timing during R / L traveling by the internal combustion engine by controlling the central angle at the time of R / L traveling by the internal combustion engine. A control device for an internal combustion engine for a vehicle. A variable lift / operating angle mechanism that can simultaneously and continuously expand and contract the lift / operating angle of the intake valve, a variable phase mechanism that delays the phase of the central angle of the lift of the intake valve, and the rotational speed of the internal combustion engine And means for detecting the load, control means for controlling the lift / operating angle and central angle of the intake valve in accordance with the engine speed and load, a motor for rotationally driving the internal combustion engine, and a vehicle capable of being driven And a second motor for stopping the ignition operation of the internal combustion engine when the vehicle is stopped and when the vehicle is traveling at a low speed, and running the second motor, and starting the internal combustion engine with the motor during a predetermined vehicle acceleration. The internal combustion engine for the vehicle is configured so that the ignition operation is restarted and the intake valve closing timing is controlled before the bottom dead center by the lift / operating angle variable mechanism and the phase variable mechanism during R / L traveling The control device Seki,
Immediately before the stop of the internal combustion engine due to vehicle operating conditions, the lift / operating angle of the intake valve is controlled to be smaller than the lift / operating angle during R / L traveling using the engine generated torque, and the center of the intake valve is controlled. The angle is controlled to be more advanced than the center angle during R / L travel using engine-generated torque, and the intake valve closing timing is before bottom dead center and during R / L travel using engine-generated torque. A control apparatus for an internal combustion engine for a vehicle, characterized by being on the advance side with respect to the closing timing.   When suddenly starting from a vehicle stop state, after starting cranking and fuel injection and ignition of the internal combustion engine at the lift / operating angle, the intake valve closing timing is set by retarding the central angle of the intake valve. 3. The control apparatus for an internal combustion engine for a vehicle according to claim 1, wherein the control is performed so as to approach the bottom dead center.   Upon sudden acceleration from the motor running by the second motor, after starting cranking, fuel injection and ignition of the internal combustion engine at the lift / operating angle, the center angle of the intake valve is retarded to The control apparatus for an internal combustion engine for a vehicle according to claim 2, wherein the valve closing timing is controlled to approach the bottom dead center.   At the time of slow start from the vehicle stop state, after starting cranking of the internal combustion engine at the lift / operating angle, fuel injection and ignition are started when a predetermined number of revolutions is reached, and the intake valve 3. The control apparatus for an internal combustion engine for a vehicle according to claim 1, wherein the central angle is controlled to a predetermined advance position corresponding to the load and the rotational speed of the engine.   At the time of slow acceleration from the motor running by the second motor, after starting cranking of the internal combustion engine at the lift / operating angle, fuel injection and ignition are started when a predetermined number of revolutions is reached, 3. The control apparatus for an internal combustion engine for a vehicle according to claim 2, wherein the central angle of the intake valve is controlled to a predetermined advance position corresponding to the load and the rotational speed of the engine. The variable lift / operating angle mechanism includes an eccentric cam that is rotationally driven by a drive shaft, a link arm that is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, 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 that is connected to the rocker arm via a link and rocks 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 control device for an internal combustion engine for a vehicle according to any one of claims 1 to 6 , wherein the lift and the operating angle of the intake valve are simultaneously increased or decreased. The phase variable mechanism is disposed so as to be rotatable concentrically with the drive shaft, and is mounted between the sprocket and the drive shaft between a sprocket driven by a crankshaft via a chain or a timing belt, and relative to each other. The vehicle internal combustion engine control device according to claim 7 , further comprising: a means for changing a general phase.

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