WO2016104733A1

WO2016104733A1 - Control device for internal combustion engine

Info

Publication number: WO2016104733A1
Application number: PCT/JP2015/086298
Authority: WO
Inventors: 大也白井; 守人浅野; 智也太田
Original assignee: トヨタ自動車株式会社
Priority date: 2014-12-26
Filing date: 2015-12-25
Publication date: 2016-06-30
Also published as: JP2016125364A

Abstract

The objective is to obtain suitable combustion from the beginning of cranking, and achieve rapid starting of an internal combustion engine. This control device, which controls an internal combustion engine equipped with a variable valve timing mechanism capable of changing the valve-opening timing or the valve-closing timing of an intake valve, is configured such that cranking, in which the crankshaft of the internal combustion engine is rotationally driven by an electric motor, is executed when the internal combustion engine is started, the valve-opening timing or the valve-closing timing of the intake valve is changed by means of the variable valve timing mechanism during cranking, and the fuel injection amount and the ignition timing are adjusted during cranking in accordance with the changing valve-opening timing or valve-closing timing of the intake valve.

Description

Control device for internal combustion engine

The present invention relates to a control device for controlling an internal combustion engine with a variable valve timing mechanism that can change the valve opening timing and / or valve closing timing of an intake valve.

2. Description of the Related Art An internal combustion engine mounted on a vehicle or the like is known with a VVT mechanism that can variably control the opening / closing timing of an intake valve (see, for example, the following patent document).

JP 2014-066627 A

When starting the internal combustion engine, the engine rotation is accelerated by burning the fuel while performing cranking for rotationally driving the internal combustion engine with an electric motor. The shorter the time spent for this starting process, the better.

The purpose of the present invention is to obtain good combustion from the initial stage of cranking and realize quick start of the internal combustion engine.

In order to solve the above-described problems, the present invention controls an internal combustion engine attached with a variable valve timing mechanism capable of changing the valve opening timing and / or the valve closing timing of the intake valve. When starting an internal combustion engine with cranking that rotationally drives the crankshaft by an electric motor, the opening and / or closing timing of the intake valve at a time when the engine speed is less than the predetermined speed, and the engine speed is the predetermined speed The advance angle is made in comparison with that at the above timing, and the advance amount of the opening timing and / or closing timing of the intake valve at the former timing depends on the temperature of the internal combustion engine and / or the temperature of the intake air. A control device for the internal combustion engine to be changed is configured.

If the idle stop end condition is satisfied and the internal combustion engine is restarted after the idle stop condition is satisfied and the idle stop process of the internal combustion engine is started and before the engine rotation is completely stopped, the engine speed It is preferable that the valve opening timing and / or valve closing timing of the intake valve at a time when the engine speed is less than the predetermined rotational speed be equal to that at the time when the engine rotational speed is equal to or higher than the predetermined rotational speed.

According to the present invention, good combustion can be obtained from the initial stage of cranking, and the internal combustion engine can be started quickly.

The figure which shows schematic structure of the internal combustion engine and control apparatus in one Embodiment of this invention. The timing diagram explaining the content of the control which the control apparatus of the embodiment implements.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type 4-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

The exhaust passage 4 for exhausting exhaust guides the exhaust generated by burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

The exhaust gas recirculation (Exhaust Gas Recirculation) device 2 realizes a so-called high pressure loop EGR, and an external EGR that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3. The passage 21, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of EGR gas flowing through the EGR passage 21 are used as elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, particularly to the surge tank 33.

The internal combustion engine of this embodiment is accompanied by a VVT mechanism 6 that can variably control the opening / closing timing of the intake valve of each cylinder 1. The VVT mechanism 6 is a known one (motor drive VVT) in which the rotation phase of the intake camshaft that drives the intake valve of each cylinder 1 with respect to the crankshaft is changed by an electric motor. As is well known, an intake camshaft of an internal combustion engine is supplied with a rotational driving force from a crankshaft that is an output shaft of the internal combustion engine, and rotates following the crankshaft. A winding transmission device (not shown) for transmitting a rotational driving force is interposed between the crankshaft and the intake camshaft. The winding transmission includes a crank sprocket (or pulley) provided on the crankshaft side, a cam sprocket (or pulley) provided on the intake camshaft side, and a timing chain (or pulley) wound around these sprockets (or pulleys). Or a belt) as an element. The VVT mechanism 6 changes the rotation phase of the intake camshaft relative to the crankshaft by rotating the intake camshaft relative to the cam sprocket, thereby changing the opening / closing timing of the intake valve.

The internal combustion engine in the present embodiment performs mirror cycle (Atkinson cycle) operation by delaying the closing timing of the intake valve larger than the intake bottom dead center (for example, 55 ° CA (crank angle) or more) as necessary. Can do. The opening timing of the intake valve when the mirror cycle operation is performed is delayed until the exhaust top dead center or a timing slightly delayed (for example, about 5 ° CA) from the exhaust top dead center.

ECU (Electronic Control) which is a control device of the internal combustion engine of the present embodiment
(Unit) 0 is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

The input interface of the ECU 0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, and an accelerator pedal. Accelerator opening signal c output from a sensor that detects the amount of depression of the engine or the opening of the throttle valve 32 as an accelerator opening (so-called required load), output from a water temperature sensor that detects a cooling water temperature that indicates the temperature of the internal combustion engine The cooling water temperature signal d, the battery current / voltage signal e output from the current / voltage sensor that detects the terminal current and / or terminal voltage of the vehicle battery, and the intake air temperature in the intake passage 3 (particularly, the surge tank 33) And intake air temperature / intake pressure signal f output from the temperature / pressure sensor for detecting intake pressure, intake camshaft Cam angle signal g output from the cam angle sensor at multiple cam angles, output from a sensor (such as a brake switch or a master cylinder pressure sensor) that detects whether the brake pedal is depressed or the brake pedal is depressed A brake signal h or the like is input.

The crank angle sensor senses the rotation angle of a rotor that is fixed to the shaft end of the crankshaft and rotates together with the crankshaft. The rotor is formed with teeth or protrusions at predetermined angles along the rotation direction of the crankshaft. Typically, each time the crankshaft rotates 10 °, teeth or protrusions are placed. The crank angle sensor faces the outer periphery of the rotor, detects that individual teeth or protrusions pass near the sensor, and transmits a pulse signal as a crank angle signal b each time. However, the crank angle sensor does not output 36 pulses during one revolution of the crankshaft. Some of the teeth or protrusions of the rotor of the crankshaft are missing. Each missing tooth portion corresponds to a specific rotational phase angle of the crankshaft. Due to the missing tooth portion, a part of the pulse train of the crank angle signal b is also lost. Based on this missing pulse, the absolute angle (posture) of the crankshaft, in other words, the current position of the piston of each cylinder 1 can be known.

The cam angle sensor senses the rotation angle of the rotor fixed to the shaft end of the intake camshaft and rotating integrally with the intake camshaft. Teeth or protrusions are formed on the rotor at predetermined angles along the rotation direction of the intake camshaft. The cam angle sensor faces the outer periphery of the rotor, detects that individual teeth or protrusions pass near the sensor, and transmits a pulse signal as the cam angle signal g each time. If both the crank angle signal b and the cam angle signal g are referred to, the current stroke of each cylinder 1 can be determined and known, and the current intake valve timing (the advance angle of the VVT mechanism 6) is realized. Amount) becomes clear.

From the output interface of the ECU 0, the ignition signal i for the igniter, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, the opening operation signal l for the EGR valve 23, VVT. An intake valve timing control signal n or the like is output to the mechanism 6.

The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR rate) Volume), opening / closing timing of the intake valve, and the like. The ECU 0 applies various control signals i, j, k, l, and n corresponding to the operation parameters via the output interface.

ECU0 executes an idle stop that stops the idle rotation of the internal combustion engine when a predetermined idle stop condition is satisfied. The ECU 0 indicates that the brake pedal depression amount or the master cylinder pressure is equal to or greater than a threshold value (the brake pedal is depressed), the cooling water temperature of the internal combustion engine is higher than a predetermined value, and the charge amount or terminal voltage of the in-vehicle battery exceeds a predetermined value. High, the air conditioner's refrigerant compression compressor is not operating, the shift range is the traveling range, there is a history of acceleration from the end of the previous idle stop to a certain vehicle speed and below the current vehicle speed The idle stop condition is established because all the conditions such as (the vehicle speed has decreased from 13.5 km / h to 13 km / h, or from 9.5 km / h to 7 km / h) are all established. Judgment is made.

When the predetermined idle stop termination condition is satisfied after the idle stop condition is satisfied, the internal combustion engine is restarted. The ECU 0 determines that the brake pedal depression amount or the master cylinder pressure is 0 or less than a threshold value close to 0 (the brake pedal is no longer depressed), and conversely, the brake pedal depression amount or the master cylinder pressure further increases (brake The idle stop termination condition is met when the pedal is depressed more), the accelerator opening is increased (the accelerator pedal is depressed), or the predetermined time (3 minutes) has elapsed in the idle stop state. Judge that it was done.

When starting the stopped internal combustion engine (a cold start or a return from an idling stop), the ECU 0 controls an electric motor (starter motor or ISG (Integrated Starter Generator), not shown). The signal o is input and cranking is performed by rotating the crankshaft by the electric motor. Cranking ends when the internal combustion engine starts from the first explosion to a continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the coolant temperature, etc. (assuming that the explosion has been completed) To do.

Thus, in the present embodiment, the opening / closing timing of the intake valve is changed via the VVT mechanism 6 during cranking for starting the internal combustion engine, and fuel injection during cranking is performed according to the changed intake valve timing. The amount and ignition timing are changed.

FIG. 2 shows an example of the control executed by the ECU 0 when starting the stopped internal combustion engine. While the internal combustion engine is stopped, the VVT mechanism 6 returns the rotational phase of the intake camshaft to the crankshaft to the most retarded position. Thereby, the opening / closing timing of the intake valve becomes the most delayed timing. At this most retarded angle timing, the intake valve opens at a timing near exhaust top dead center or slightly delayed from exhaust top dead center, and closes at timing greatly delayed from intake bottom dead center.

The ECU 0 starts the control of the VVT mechanism 6 almost simultaneously with starting the electric motor for rotationally driving the crankshaft of the internal combustion engine, and the rotational phase of the intake camshaft with respect to the crankshaft is more than a certain degree from the most retarded position (for example, 20 (° CA to 25 ° CA) Displace to the advanced position. In FIG. 2, time t ₀ is the start time of cranking. After the time t ₀ , the opening / closing timing of the intake valve during cranking gradually advances from the most retarded timing.

When the intake valve timing is advanced from the most retarded timing, the intake valve opening timing is earlier than the exhaust top dead center. Further, as the intake valve timing is advanced from the most retarded timing, the intake valve closing timing approaches the intake bottom dead center, and the amount of intake gas charged into the cylinder 1 increases. Therefore, the ECU 0 increases the amount of fuel injected from the injector 11 to the cylinder 1 that reaches the intake stroke during cranking as the advance amount from the most retarded timing of the intake valve timing increases. As already described, the advance amount of the current intake valve timing can be obtained by referring to the crank angle signal b and the cam angle signal g. The fuel injection amount from the injector 11 is determined on the basis of the advance amount of the intake valve timing at the exhaust top dead center of the target cylinder 1 or at the timing just before that.

Note that the intake amount to be filled in the current intake stroke of the cylinder 1 is predicted from the advance amount of the intake valve timing at the exhaust top dead center of the target cylinder 1 or the timing immediately before it, the engine speed, etc. An amount of fuel commensurate with the anticipated intake amount may be injected. For example, the relationship between the advance amount of the intake valve timing and the engine speed in the memory of the ECU 0 and the expected value of the intake amount that is charged into the cylinder 1 through the intake stroke (or the fuel injection amount that matches the expected intake amount) The map data or function formula that prescribes is stored in advance. Then, at the exhaust top dead center of a certain cylinder 1 or at the timing just before it, the intake air that is filled in that cylinder 1 by searching the map with the advance amount of the current intake valve timing and the engine speed as keys. Knowing the expected amount of fuel (or fuel injection amount) or substituting the current intake valve timing advance amount and engine speed into the function equation, and predicting the amount of intake air that will fill the cylinder 1 The value (or fuel injection amount) is calculated. Then, the amount of fuel injected from the injector 11 to the cylinder 1 is determined.

At this time, it is also preferable to correct the fuel injection amount from the injector 11 in accordance with the current temperature of the internal combustion engine and the temperature of the intake air. Specifically, as the cooling water temperature of the internal combustion engine obtained by referring to the cooling water temperature signal d is lower, the port wet (the fuel injected from the injector 11 becomes liquid and adheres to the inner wall surface of the intake port). ) Increases, the fuel injection amount is corrected to increase. And / or the lower the intake air temperature known with reference to the intake air temperature signal f, the greater the amount of oxygen contained in the intake air charged into the cylinder 1 (the higher the oxygen density), so the fuel injection amount Correct the increase.

Further, as the intake valve timing is advanced from the most retarded timing, the intake amount and the fuel injection amount charged into the cylinder 1 increase, so that the combustion speed in the expansion stroke of the cylinder 1 becomes faster. The timing at which spark ignition by the spark plug 12 is performed on the cylinder 1 that reaches the expansion stroke during cranking is delayed as the advance amount from the most retarded timing of the intake valve timing increases. The spark ignition timing is determined based on the advance amount of the intake valve timing at the exhaust top dead center of the target cylinder 1 or the timing just before it.

Note that the intake amount to be filled in the current intake stroke of the cylinder 1 is predicted from the advance amount of the intake valve timing at the exhaust top dead center of the target cylinder 1 or the timing immediately before it, the engine speed, etc. You may make it perform spark ignition at the timing according to the estimated intake amount. For example, in the memory of the ECU 0, the advance amount of the intake valve timing, the engine speed, and the like, the expected value of the intake amount that is charged into the cylinder 1 through the intake stroke (or an appropriate ignition timing for the expected intake amount), and Map data or a function expression that defines the relationship is stored in advance. Then, at the exhaust top dead center of a certain cylinder 1 or at the timing just before it, the intake air that is filled in that cylinder 1 by searching the map with the advance amount of the current intake valve timing and the engine speed as keys. Knowing the expected value (or ignition timing) of the quantity, or substituting the current advance amount of the intake valve timing and the engine speed into the function formula, the expected value of the intake quantity filled in the cylinder 1 (Or ignition timing) is calculated. And the timing which performs spark ignition with the spark plug 12 attached to the said cylinder 1 is determined.

At this time, it is also preferable to correct the timing of spark ignition by the spark plug 12 according to the current intake air temperature level. Specifically, the lower the intake air temperature obtained with reference to the intake air temperature signal f, the slower the combustion speed of the air-fuel mixture filled in the cylinder 1, so the ignition timing is corrected to advance.

As shown in FIG. 2, at the time when the engine speed has increased to a predetermined speed, or after time t ₁ when the engine speed exceeds the complete explosion determination value and cranking ends, the idle operation region or idle operation is performed. The opening / closing timing of the intake valve in the low load operation region close to is controlled to a normal timing, that is, a timing advanced by a certain degree (for example, 20 ° CA to 25 ° CA) from the most retarded timing.

In this embodiment, the VVT mechanism 6 capable of changing the opening / closing timing of the intake valve is controlled, and when starting the internal combustion engine, the crankshaft of the internal combustion engine is rotationally driven by an electric motor. While performing cranking, the intake valve opening / closing timing is changed via the VVT mechanism 6 during the cranking, and the fuel injection amount and ignition timing during cranking are adjusted according to the changing intake valve opening / closing timing. The control device 0 for the internal combustion engine is configured.

According to the present embodiment, since the fuel injection amount and the ignition timing can be set in accordance with the intake air amount actually charged in the cylinder 1 during cranking for starting, it is favorable from the initial stage to the final stage of cranking. You can get combustion. As a result of stabilization of combustion, engine rotation can be accelerated quickly, and the cranking period can be shortened.

Note that the present invention is not limited to the embodiment described in detail above. In particular, the specific mode of the VVT mechanism 6 for changing the valve opening timing and / or the valve closing timing of the intake valve of each cylinder 1 of the internal combustion engine is arbitrary and is not uniquely limited. In addition to those that advance / retard the rotation phase of the intake camshaft with respect to the crankshaft, multiple cams that drive the intake valve to open are prepared and used appropriately. The lever ratio of the rocker arm Are known, and the intake valve is an electromagnetic solenoid valve, etc., and it is allowed to be selected from these various mechanisms.

In the VVT mechanism 6 in which the rotation phase of the intake camshaft relative to the crankshaft is advanced / retarded, the valve opening timing and the valve closing timing of the intake valve change synchronously, but the VVT mechanism 6 in other aspects Is mounted on the internal combustion engine, the valve opening timing and the valve closing timing of the intake valve can be changed asynchronously, or only the valve opening timing or only the valve closing timing can be changed. Therefore, the advance amount from the most retarded timing of the intake valve opening timing may be different from the advance amount from the most retarded timing of the same intake valve closing timing.

It is possible to increase / decrease the intake air amount filled in the combustion chamber of the cylinder 1 even if only the intake valve closing timing is advanced / retarded. Further, if the internal combustion engine can perform the mirror cycle operation by delaying the opening timing of the intake valve largely from the exhaust top dead center, the cylinder opening / closing angle is set by advancing / retarding only the opening timing of the intake valve. It is possible to increase / decrease the amount of intake air charged in one combustion chamber. In these cases, as in the above embodiment, the fuel injection amount and ignition timing during cranking are adjusted according to the valve opening timing or valve closing timing (advancing amount) of the intake valve that changes during cranking. do it. That is, the fuel injection amount is increased and the ignition timing is delayed as the opening timing or closing timing of the intake valve is advanced, in other words, as the intake amount charged into the cylinder 1 is increased.

Other specific configurations of each part can be variously modified without departing from the gist of the present invention.

The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 6 ... Variable valve timing (VVT) mechanism b ... Crank angle signal g ... Cam angle signal i ... Ignition signal j ... Fuel injection signal n ... Control signal of intake valve timing o ... Cranking Motor control signal

Claims

Controlling an internal combustion engine with a variable valve timing mechanism that can change the opening timing or closing timing of the intake valve,
When starting the internal combustion engine, the crankshaft for rotating the crankshaft of the internal combustion engine by an electric motor is executed,
During the cranking, the valve opening timing or valve closing timing of the intake valve is changed via the variable valve timing mechanism,
A control device for an internal combustion engine that adjusts the fuel injection amount and the ignition timing during cranking according to the opening timing or closing timing of the intake valve that changes.