JP6835129B2 - Internal combustion engine control device - Google Patents

Description

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

The starting acceleration performance of a vehicle can be said to be one of the qualities necessary to make a vehicle attractive. According to Patent Document 1 previously proposed by the present applicant, in an internal combustion engine for a vehicle provided with a variable compression ratio mechanism capable of changing the mechanical compression ratio, the vehicle starts when the driver releases the brake pedal while the vehicle is stopped. A technique for changing the compression ratio to the low compression ratio side is disclosed as required. That is, when the brake pedal is released, the change to the compression ratio suitable for starting is started prior to the driver's depression of the accelerator pedal.

JP-A-2010-185416

However, in the technique of Patent Document 1, the change of the compression ratio is only started immediately before the start, for example, in a situation where the driver depresses the accelerator pedal almost at the same time as releasing the brake pedal, the start is started. Occasionally, the reduction in compression ratio may not be sufficient. Therefore, there was still room for improvement in terms of start acceleration performance.

The present invention is a control device for an internal combustion engine equipped with a variable compression ratio mechanism that is mounted on a vehicle to drive drive wheels and can change the mechanical compression ratio, and targets compression based on a load and a rotation speed. In an internal combustion engine control device that sets the ratio and sets the target air-fuel ratio to be lower as the load is higher
At the first timing during deceleration due to the decrease in the accelerator opening, it is determined whether or not the predetermined high torque response requirement condition that the internal combustion engine is required to have a relatively high torque response during the subsequent reacceleration is satisfied. If the high torque response requirement is satisfied, turn on the flag and turn on the flag.
If the flag is ON, after the first timing, the variable compression is performed at the second timing when the rotation speed of the internal combustion engine becomes equal to or less than the idle determination rotation speed or the vehicle speed becomes equal to or less than the vehicle stop determination vehicle speed. The compression ratio change is started by setting the target compression ratio of the ratio mechanism to a low compression ratio suitable for a high torque response, and the compression ratio change is continued until the target air-fuel ratio is reached .

That is, it is determined whether or not a high torque response is required at the time of subsequent reacceleration during deceleration, and if it is determined that a high torque response is required, the rotation speed of the internal combustion engine is determined to be the idle speed after deceleration. When the vehicle speed becomes equal to or less than the vehicle stop judgment vehicle speed, the compression ratio change with the target compression ratio as the low compression ratio is started.

According to the present invention, after deceleration of the internal combustion engine, the low compression ratio is started when the rotation speed of the internal combustion engine becomes equal to or less than the idle determination rotation speed or when the vehicle speed becomes equal to or less than the vehicle stop determination vehicle speed. , There is no problem of response delay of changing the mechanical compression ratio, and high start acceleration performance can be obtained at the time of subsequent start.

A configuration explanatory view showing a system configuration of a control device according to an embodiment of the present invention. A time chart showing an example of control during vehicle deceleration / acceleration.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a system configuration of an internal combustion engine 1 for an automobile to which the present invention is applied. The internal combustion engine 1 is, for example, an in-cylinder direct injection spark ignition internal combustion engine with a 4-stroke cycle turbocharger equipped with a variable compression ratio mechanism 2 using a double-link piston crank mechanism, and is a combustion chamber 3 A pair of intake valves 4 and a pair of exhaust valves 5 are arranged on the ceiling wall surface of the engine, and a spark plug 6 is arranged in a central portion surrounded by these intake valves 4 and exhaust valves 5.

A fuel injection valve 8 for injecting fuel toward the intake valve 4 is arranged at the intake port 7 opened and closed by the intake valve 4. The fuel injection valve 8 is an electromagnetic or piezoelectric injection valve that opens when a drive pulse signal is applied, and injects an amount of fuel substantially proportional to the pulse width of the drive pulse signal. .. In the present invention, the engine may be configured as an in-cylinder direct injection engine that injects fuel directly into the cylinder.

An electronically controlled throttle valve 11 whose opening degree is controlled by a control signal from the engine controller 10 is interposed on the upstream side of the collector portion 9a of the intake passage 9 connected to the intake port 7, and further upstream thereof. A compressor 12A of the turbocharger 12 is arranged on the side. An air flow meter 13 for detecting the amount of intake air and an air cleaner 14 are arranged on the upstream side of the compressor 12A. An intercooler 16 is provided between the compressor 12A and the throttle valve 11.

The intake valve 4 includes an intake side variable valve mechanism 15 capable of variably controlling the opening / closing timing of the intake valve 4. The variable valve mechanism 15 may have a structure in which the opening time and the closing time can be individually changed independently, or the opening time and the closing time may be delayed at the same time. In this embodiment, the latter type in which the phase of the intake side camshaft (not shown) is delayed with respect to the crankshaft 31 is used.

On the other hand, the turbine 12B of the turbocharger 12 is arranged in the exhaust passage 22 connected to the exhaust port 21 in which the exhaust valve 5 opens and closes, and the catalyst device 23 composed of a three-way catalyst is located downstream of the turbine 12B. Is intervened. A wastegate valve 24 is provided at the inlet of the turbine 12B to guide a part of the exhaust gas by bypassing the turbine 12B for boost pressure control. The wastegate valve 24 has an electronically controlled configuration in which the opening degree is controlled by the electric actuator 24a.

The exhaust valve 5 includes an exhaust side variable valve mechanism 26 capable of variably controlling the opening / closing timing of the exhaust valve 5. The variable valve mechanism 26 may have a structure in which the opening time and the closing time can be individually changed independently, or the opening time and the closing time may be delayed at the same time. In this embodiment, similarly to the intake side variable valve mechanism 15, the latter type that delays the phase of the intake side camshaft (not shown) with respect to the crankshaft 31 is used.

On the other hand, the variable compression ratio mechanism 2 utilizes a known double-link piston crank mechanism described in Patent Document 1 and the like, and has a lower link 32 rotatably supported by a crankpin 31a of the crankshaft 31. The upper link 35 connecting the upper pin 33 at one end of the lower link 32 and the piston pin 34a of the piston 34 to each other, and the control link 37 having one end connected to the control pin 36 at the other end of the lower link 32. It is mainly composed of a control shaft 38 that swingably supports the other end of the control link 37. The crankshaft 31 and the control shaft 38 are rotatably supported by a bearing portion 40 at the bottom of the cylinder block 39.

The control shaft 38 has an eccentric shaft portion 38a whose position changes with the rotation of the control shaft 38, and the end portion of the control link 37 is rotatably fitted to the eccentric shaft portion 38a. It fits. In the variable compression ratio mechanism 2, the top dead center position of the piston 34 is displaced up and down with the rotation of the control shaft 38, and therefore the mechanical compression ratio changes.

Further, as a drive mechanism for variably controlling the compression ratio of the variable compression ratio mechanism 2, an actuator 41 made of an electric motor is provided. The actuator 41 drives the control shaft 38 in the rotational direction via an appropriate reduction mechanism. As a result, the mechanical compression ratio is controlled to the target compression ratio as described above.

The internal combustion engine 1 is mounted on a vehicle in combination with a torque converter (not shown) and a stepped or stepless automatic transmission (schematically shown by the block of reference numeral 42), and the transmission 42 and FIG. The drive wheels of the vehicle are driven via a final deceleration device (not shown). In the present invention, the starting clutch may be engaged and disengaged by an electromagnetic actuator without using a torque converter.

In addition to the air flow meter 13, the engine controller 10 includes a crank angle sensor 45 for detecting the engine rotation speed, a vehicle speed sensor 46 for detecting the vehicle speed of the vehicle, and an accelerator pedal depression amount operated by the driver. The detection signals of sensors such as the accelerator opening sensor 47 to be detected are input. Further, the AT controller 43 that controls the gear ratio of the automatic transmission 42 and the like is connected to the engine controller 10 via the in-vehicle network 44, and necessary information and signals are exchanged between the two. With respect to the present invention, at least information on the current shift stage is given from the AT controller 43 to the engine controller 10, and conversely, a shift command can be output from the engine controller 10 to the AT controller 43.

Based on these detection signals, the engine controller 10 determines the fuel injection amount and injection timing by the fuel injection valve 8, the ignition timing by the spark plug 6, the opening degree of the throttle valve 11, the opening / closing timing of the intake valve 4 and the exhaust valve 5, and the waist. The opening degree of the gate valve 24, the target compression ratio of the variable compression ratio mechanism 2, and the like are optimally controlled. The target compression ratio of the variable compression ratio mechanism 2 is mainly set based on the load of the internal combustion engine 1 and the engine rotation speed. Basically, the higher the load, the lower the target compression ratio to avoid knocking. Become.

Further, the vehicle equipped with the internal combustion engine 1 is equipped with a gravity sensor 49 that detects the slope of the road surface of the vehicle (the slope of the vehicle), and further, the driving mode switching for selecting the driving mode by the driver. It has a switch 50. These detection signals are also input to the engine controller 10. The driving mode includes, for example, a normal mode, an economy mode that prioritizes reduction of fuel consumption rate, and a sports mode that prioritizes driving performance. For example, the shifting characteristic of the automatic transmission 42 and the opening characteristic of the throttle valve 11. Etc. are changed according to each driving mode.

Next, the control during deceleration and reacceleration of the internal combustion engine 1 configured as described above will be described with reference to the time chart of FIG.

FIG. 2A shows the accelerator opening detected by the accelerator opening sensor 47 or the opening degree of the throttle valve 11 that changes in conjunction with the accelerator opening. In this example, the accelerator pedal is released at time t0. The deceleration operation is performed, and the reacceleration operation is performed by depressing the accelerator pedal at time t2.

(B) shows a change in the engine rotation speed detected by the crank angle sensor 45 or the vehicle speed detected by the vehicle speed sensor 46, and the engine rotation speed or the vehicle speed decreases with the deceleration operation of the driver, and the engine rotation speed or the vehicle speed decreases again. The engine speed or vehicle speed increases with the acceleration operation.

Here, the threshold value indicated by the line SL in the figure indicates a predetermined idle determination rotation speed or vehicle stop determination vehicle speed to be compared with the engine rotation speed or the vehicle speed during deceleration, and the engine rotation speed is equal to or less than this idle determination rotation speed. When becomes, it is determined that the internal combustion engine 1 is in an idle state (including an idle stop state), or when the vehicle speed becomes equal to or lower than this vehicle stop determination vehicle speed, it is considered that the vehicle is substantially stopped. It is judged. In the illustrated example, at time t1, it becomes equal to or less than the idle determination rotation speed or the vehicle stop determination vehicle speed.

(C) of the figure shows a sudden acceleration request flag indicating whether or not a high torque response request, for example, a sudden acceleration request is predicted at the time of reacceleration after deceleration. In this embodiment, this sudden acceleration request flag is appropriately set during deceleration based on whether or not the driving mode is the sports mode and whether or not the slope of the road surface is equal to or higher than a predetermined value (that is, so-called starting on a slope). (Corresponding to the "first timing" in the claims) . For example, if the traveling mode is the sports mode, the sudden acceleration request flag is ON, and similarly, if the road surface slope is equal to or higher than a predetermined value, the sudden acceleration request flag is ON. In other cases, the sudden acceleration request flag is turned off. In the example of the figure, for example, the sudden acceleration request flag is ON because the running mode is the sports mode.

(D) indicates a compression ratio transition permission flag indicating whether or not to allow a change to a target compression ratio suitable for sudden acceleration (high torque response) as torque increase promotion control prepared for re-acceleration. When the engine speed or vehicle speed is equal to or less than the threshold SL and the sudden acceleration request flag is ON, this compression ratio transition permission flag is ON. Therefore, in the illustrated example, the compression ratio transition permission flag is turned ON at time t1. This time t1 corresponds to the "second timing" in the claims.

As the compression ratio transition permission flag is turned ON, the variable compression ratio mechanism 2 changes the compression ratio toward the target compression ratio suitable for sudden acceleration at time t1 as shown in (e). Start. The target compression ratio at this time is set to a relatively low compression ratio in order to avoid knocking at a high load, and for example, the lowest compression ratio within the controllable range is used. This change in the compression ratio is continued until the target compression ratio is reached, for example, even after the vehicle is stopped or the internal combustion engine 1 is in the idle stop state. Therefore, the vehicle is kept in a stopped state when the target compression ratio is reached.

Therefore, when the driver depresses the accelerator pedal at time t2, the variable compression ratio mechanism 2 is already in a predetermined low compression ratio state, and transient knocking due to response delay or ignition timing retard due to knocking detection occurs. Good start acceleration performance can be obtained without causing such problems.

In this embodiment, as the torque increase promotion control, in addition to lowering the compression ratio, some additional controls are performed as shown in (f) to (i). (F) shows the opening degree of the wastegate valve 24 of the turbocharger 12, and the opening degree is reduced and corrected in advance at time t1 as the compression ratio transition permission flag is turned ON. .. Therefore, a high boost pressure can be obtained when the driver depresses the accelerator pedal at time t2. At this time, since the compression ratio is already low, knocking is avoided even at a high boost pressure.

(G) shows the change in the intake valve closing timing by the intake side variable valve mechanism 15. In this example, when the load is low (that is, between times t0 to t1), the intake valve closing time is set at a time relatively large behind the bottom dead center due to so-called late closing, but the compression ratio transition permission flag is set. Along with the ON, the intake valve closing timing is preliminarily corrected to the bottom dead center side at time t1. Therefore, when the driver depresses the accelerator pedal at time t2, a high effective compression ratio can be obtained from the initial stage of acceleration. When the intake valve closing timing is set on the advance angle side of the bottom dead center as so-called early closing when the load is low, the retard angle is corrected toward the bottom dead center.

(H) shows the change in valve overlap determined by the exhaust valve closing timing by the exhaust side variable valve mechanism 26 and the intake valve opening timing by the intake side variable valve mechanism 15, and the compression ratio transition permission flag is ON. As a result, the valve overlap is reduced and corrected at time t1 as well. In this example, since the intake valve opening time also advances with the advance angle of the intake valve closing time as shown in (g), the reduction of the valve overlap is mainly due to the advance angle of the exhaust valve closing time. Realized by. By reducing the valve overlap in this way, the internal EGR is reduced, so that the amount of fresh air at the time of starting acceleration is substantially increased, and the torque can be increased.

(I) shows a change in the gear ratio of the automatic transmission 42, and a shift command is output from the engine controller 10 to the AT controller 43 at time t1 as the compression ratio transition permission flag is turned ON. , The gear is changed to the "High" side gear ratio, that is, a relatively small gear ratio. As a result, when the driver depresses the accelerator pedal at time t2, knocking is less likely to occur, and ignition timing retard associated with knocking detection can be avoided, so that the power performance is improved. Further, since the gas flow rate introduced into the turbine 12B of the turbocharger 12 increases, the boost pressure rises faster and the start acceleration performance is improved.

The various torque increase promotion controls described above can be used alone or in combination as appropriate.

In the above embodiment, in addition to the case where the driving mode is the sports mode, when the slope of the road surface is equal to or higher than a predetermined value, the torque increase promotion control is executed in advance assuming that a high torque response request is predicted, so that when starting on a slope. Hesitation and sliding of the vehicle are surely prevented.

In addition to the sport mode selection and road surface gradient described above, some examples of expected high torque response requirements include:

In one example, the vehicle is provided with a detection means such as a load sensor for detecting the vehicle load capacity, and it is predicted that there is a high torque response request when the vehicle load capacity is equal to or more than a predetermined value.

In one example, the vehicle is provided with means for detecting that it is towing another object, such as a trailer, and predicts that there will be a high torque response requirement during such towing travel.

By performing the above-mentioned torque increase promotion control only when a specific condition is satisfied in this way, it is possible to achieve both improvement in power performance and reduction in fuel consumption.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the present invention is, as in the above embodiments, limited turbocharger 12, the intake variable valve mechanism 15, the exhaust-side variable valve operating mechanism 26, the running mode switching mechanism, and the like to that provided all However, these combinations are arbitrary.

1 ... internal combustion engine 2 ... variable compression ratio mechanism 10: engine controller 12 ... turbocharger 15 ... intake variable valve mechanism 24 ... waist gate valve 26 ... exhaust side variable valve operating mechanism 42 ... automatic transmission 45 ... Crank angle Sensor 46 ... Vehicle speed sensor 47 ... Accelerator opening sensor 49 ... Gravity sensor 50 ... Driving mode selector switch

Claims (10)

It is a control device for an internal combustion engine equipped with a variable compression ratio mechanism that is mounted on a vehicle to drive the drive wheels and can change the mechanical compression ratio, and sets a target compression ratio based on the load and rotation speed. In the control device of an internal combustion engine, the target air-fuel ratio is set to be lower as the load is higher.
At the first timing during deceleration due to the decrease in the accelerator opening, it is determined whether or not the predetermined high torque response requirement condition that the internal combustion engine is required to have a relatively high torque response during the subsequent reacceleration is satisfied. If the high torque response requirement is satisfied, turn on the flag and turn on the flag.
If the flag is ON, after the first timing, the variable compression is performed at the second timing when the rotation speed of the internal combustion engine becomes equal to or less than the idle determination rotation speed or the vehicle speed becomes equal to or less than the vehicle stop determination vehicle speed. An internal combustion engine control device that starts changing the compression ratio with the target compression ratio of the ratio mechanism set to a low compression ratio suitable for high torque response, and continues to change the compression ratio until the target air-fuel ratio is reached. The internal combustion engine includes at least an intake side variable valve mechanism capable of changing the intake valve closing timing.
In the second timing, as an additional control for obtaining a high torque response at the time of reacceleration, the intake valve closing timing control for controlling the intake side variable valve mechanism so that the intake valve closing timing approaches the bottom dead center. The control device for an internal combustion engine according to claim 1. The internal combustion engine includes at least an intake side variable valve mechanism capable of changing the intake valve opening timing.
At the second timing, as an additional control for obtaining a high torque response at the time of reacceleration, the intake valve opening timing control for controlling the intake side variable valve mechanism so as to reduce the valve overlap is started. The control device for an internal combustion engine according to claim 1 or 2. The internal combustion engine is provided with an exhaust side variable valve mechanism capable of changing at least the exhaust valve closing timing.
At the second timing, as an additional control for obtaining a high torque response at the time of reacceleration, the exhaust valve closing timing control for controlling the exhaust side variable valve mechanism so as to reduce the valve overlap is started. The control device for an internal combustion engine according to any one of claims 1 to 3. The internal combustion engine includes a turbocharger with a wastegate valve.
At the second timing, as an additional control for obtaining a high torque response at the time of reacceleration, the wastegate valve control for controlling the opening degree of the wastegate valve to be reduced is started, claims 1 to 4. The control device for an internal combustion engine according to any one of. The internal combustion engine drives the vehicle via a transmission whose gear ratio can be controlled.
The invention according to any one of claims 1 to 5, wherein the control of the transmission is started so that the gear ratio becomes smaller as an additional control for obtaining a high torque response at the time of reacceleration at the second timing. Internal combustion engine control device. The vehicle is provided with a driving mode switching means that is selectively operated by the driver.
In the first timing, when the driver has selected a sport mode as the travel mode of the vehicle, it is determined that the high torque response requirements are you are satisfied, according to any of claims 1 to 6 Internal combustion engine control device. The vehicle is equipped with a means for detecting the slope of the road surface.
In the first timing, when upward gradient of the road surface is equal to or larger than the predetermined value, it is determined that the high torque response requirements are you are satisfied, control of the internal combustion engine according to claim 1 apparatus. The vehicle is equipped with a means for detecting the vehicle load capacity.
In the first timing, when the vehicle load amount is equal to or larger than the predetermined value, it is determined that the high torque response requirements are you are satisfied, the control apparatus for an internal combustion engine according to claim 1 .. The vehicle is equipped with means for detecting towing travel that is towing another object.
In the first timing, when it is said towing determines that the high torque response requirements are you are satisfied, the control device for an internal combustion engine according to any of claims 1 to 9.

Images