JP5077060B2 - Engine control device - Google Patents

Description

  The present invention relates to an apparatus for controlling an engine with a variable valve mechanism suitable for use in an automobile.

Conventionally, a reciprocating engine (hereinafter simply referred to as an engine) for automobiles having a mechanism for changing dynamic characteristics (valve lift characteristics) of intake and exhaust valves such as opening / closing timing, valve opening period and lift amount is known. It has been.
Such a mechanism is called a variable valve mechanism, and an example thereof is disclosed in Patent Document 1 below.
Japanese Patent No. 3814887

However, as in the technique disclosed in Patent Document 1, only the technique of switching the valve lift characteristics of the intake valve according to before and after the warming up of the engine is completed, the engine can be started smoothly, There is a problem that it is difficult to suppress the discharge amount of unburned fuel.
The present invention has been devised in view of such problems, and an object of the present invention is to provide an engine control device capable of improving exhaust gas performance at the time of engine start while improving engine startability.

In order to achieve the above object, an engine control apparatus according to the present invention (Claim 1) includes a cold determination means for determining whether or not an engine mounted on a vehicle is cold, and the engine is being started. A start determination means for determining whether the engine is idling after completion of start, a variable valve mechanism for driving the intake valve of the engine while at least changing the valve closing timing, and using the variable valve mechanism Intake valve control means for controlling the closing timing of the intake valve, and the intake valve control means determines that the engine is cold by the cold state determination means and the engine determination means by the start determination means Is set during the compression stroke to increase the pressure in the combustion chamber, and the engine is controlled by the cold state determining means. It is determined that it is cold and the start-up Retarded from the first intake valve closing timing of the second intake valve closing timing in the compression stroke is a closing timing of the intake valve when it is determined that the idle starting of the engine is completed by means The variable valve mechanism can further change the valve opening period of the intake valve, and the intake valve control means is controlled by the cold state determination means. A period during which both the exhaust valve and the intake valve of the engine are open when it is determined that the engine is cold and the engine determination means determines that the engine is starting. The exhaust valve when one valve overlap period is determined by the cold state determination means that the engine is cold and the start determination means determines that the engine has been started and is idle. The intake valve Second to be shorter than the valve overlap period is a period during which monitor opened, it is characterized in that to change the opening period of the intake valve.

In addition, the engine control device of the present invention according to claim 2 further includes engine temperature detection means for detecting the temperature of the engine according to claim 1 , wherein the intake valve control means includes the cold state determination. When it is determined by the means that the engine is cold, the second intake valve closing timing is corrected according to the engine temperature acquired by the engine temperature detecting means.

The control device of an engine of the present invention according to claim 3, in the context of claim 1, further comprising intake air temperature detecting means for detecting an intake air temperature of the engine, the intake valve control means, the cold state When the determination means determines that the engine is cold, the second intake valve closing timing is corrected according to the intake air temperature acquired by the intake air temperature acquisition means.

According to a fourth aspect of the present invention, there is provided the engine control device according to the second aspect , wherein the intake valve control means is configured such that the engine temperature acquired by the engine temperature acquisition means increases as the engine temperature increases. The second intake valve closing timing is delayed and corrected.
Further, in the engine control device of the present invention according to claim 5, in the content of claim 3 , the intake valve control means is configured such that the intake air temperature acquired by the intake air temperature acquisition means increases as the intake air temperature increases. The second intake valve closing timing is delayed and corrected.

The control apparatus for an engine according to the present invention of claim 6 is the contents according to any one of claims 1 to 5, the movable variable valve mechanism is continuously changing the valve opening period of the intake valve It is characterized by doing.

According to the engine control apparatus of the present invention, it is possible to improve the exhaust gas performance and the fuel consumption performance when starting the engine while improving the startability of the engine. In addition, by reducing noise and vibration during cold operation after completion of startup, improving exhaust gas performance, and suppressing the required strength of the engine structure, the weight reduction is promoted while the cost is reduced. It is possible to reduce friction during operation. (Claim 1)
Further, the combustion efficiency can be improved by reducing the amount of internal EGR gas and enhancing the in-cylinder flow, and the engine rotation can be smoothly increased. (Claim 1)
Furthermore, noise and vibration can be further suppressed, friction can be reduced, and the combustion temperature can be prevented from being increased more than necessary, and the amount of NOx components emitted can be suppressed. (Claims 2 to 5 )
In addition, the intake valve can be finely controlled by continuously changing the valve opening period of the intake valve. (Claim 6 )

Hereinafter, an engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing the overall configuration, and FIG. 2 is a schematic valve lift line showing its valve lift characteristics. FIG. 3, FIG. 3 is a schematic flowchart showing the control contents, FIG. 4 (A) is a schematic time chart comparing the closing timing of the intake valve between the prior art and the present invention, and FIG. 4 (B) is the engine. FIG. 4 (C) is a schematic time chart comparing the exhaust HC integrated amount between the conventional technique and the present invention.

As shown in FIG. 1, a vehicle 10 is equipped with a reciprocating gasoline engine (engine) 11.
A piston 14 is provided in the first cylinder 13 of the engine 11, and a combustion chamber 15 is formed above the piston 14. Here, for simplification of description, only the first cylinder 13 is shown, and the description will be focused on the first cylinder 13, but the engine 11 is a four-cylinder engine. The second to fourth cylinders (not shown) are also provided.

The engine 11 is provided with an intake manifold 16, an exhaust manifold 17, a fuel injector 18, a spark plug 19, an intake valve 21, and an exhaust valve 22.
The intake manifold 16 is a manifold that supplies air taken from outside the vehicle to the combustion chambers 15 of the first to fourth cylinders. A throttle valve 23 is provided at the intake side inlet of the intake manifold 16.

The exhaust manifold 17 is a manifold that connects each combustion chamber 15 of the first to fourth cylinders and an exhaust pipe (not shown) so that exhaust gas discharged from each combustion chamber 15 can be sent to the exhaust pipe. It has become.
The fuel injector 18 is a fuel injection device that injects fuel into the intake port 24 in accordance with an electrical signal from a fuel injection control unit (not shown) of the ECU 40 described later. Instead of the fuel injector 18, a fuel injector that injects fuel into the combustion chamber 15 (that is, an in-cylinder injector) may be used.

The spark plug 19 is provided in the cylinder head 25 so that the tip of the spark plug 19 protrudes into the combustion chamber 15, and generates a spark in the combustion chamber 15 by a high voltage current supplied from an ignition coil (not shown). The mixture can be ignited. The spark plug 19 is controlled by the ECU 40.
Intake valve 21 is a valve for opening and closing between the intake ports 2 4 and the combustion chamber 15, so as to open and close following the movement of the intake cam (not shown).

The exhaust valve 22 is a valve that opens and closes between the exhaust port 26 and the combustion chamber 15 and opens and closes following the movement of an exhaust cam (not shown).
Further, the engine 11 includes an intake variable valve operating mechanism (variable valve operating mechanism) 33 having an intake valve opening period changing mechanism 31 and an intake characteristic phase changing mechanism 32, and an exhaust variable valve operating mechanism having an exhaust characteristic phase changing mechanism 34. A mechanism (variable valve mechanism) 35 is provided.

Of these, inlet valve opening term varying mechanism 31, by continuously changing the rotational speed of the intake cam relative to the rotational speed of the crankshaft (not shown), continuously the opening term T _IO of inlet valve 21 It is a mechanism to change.
Since the structure of the intake valve opening period changing mechanism 31 is already known, the description thereof is omitted here, but in this embodiment, it is disclosed in Japanese Patent No. 3834921 and Japanese Patent Laid-Open No. 10-220209. Technology is applied.

The intake characteristic phase changing mechanism 32 is a mechanism that changes the on-off valve characteristics (intake valve lift line) L _IO1 , L _IO2 , L _IO3 of the intake valve 21 shown in FIG. 2, P _IO1 , P _IO2 , P _IO3. It is.
Similarly, the exhaust characteristic phase changing mechanism 34 is a mechanism for changing the phase P _EO1 of the exhaust valve lift line L _EO1 shown in FIG. In this embodiment, the reference embodiment described later, and other reference embodiments , the exhaust characteristic phase changing mechanism 34 keeps the phase P _EO1 of the exhaust valve lift characteristic L _EO1 constant.

The intake valve lift line L _IO1 indicates the valve lift characteristic of the intake valve 21 when the engine 11 is “cold and starting”, and is referred to as a first intake valve lift line L _IO1 .
The intake valve lift line _LIO2 indicates the valve lift characteristic of the intake valve 21 when the engine 11 is “cold and idle after completion of starting”, and is referred to as a second intake valve lift line _LIO2 .

The intake valve lift line L _IO3 indicates the valve lift characteristic of the intake valve 21 when the engine 11 is “warm and idle after completion of starting”, and is referred to as a third intake valve lift line L _IO3 .
The exhaust valve lift line L _EO1 indicates the valve lift characteristic of the exhaust valve 22.

Since the structures of the intake characteristic phase changing mechanism 32 and the exhaust characteristic phase changing mechanism 33 are already known, the description thereof is omitted here. However, in this embodiment, it is disclosed in Japanese Patent No. 3498784. Technology is applied.
Further, the vehicle 10 is provided with an engine speed sensor (rotation speed detecting means) 37, an accelerator sensor (accelerator pedal position sensor) 38, a cooling water temperature sensor (engine temperature detecting section) 39, and an ECU (Electronic Control Unit) 40. It has been.

The engine rotation speed sensor 37 detects the rotation speed NE of the engine 11 and the detection result is read by the ECU 40.
The accelerator sensor 38 detects the depression amount Acc of the accelerator pedal 30, and the detection result is read by the ECU 40.
The cooling water temperature sensor 39 detects the temperature WT of the cooling water of the engine 11, and the detection result is read by the ECU 40. The cooling water temperature WT is regarded as the temperature of the engine 11.

  The ECU 40 is an electronic control unit that includes an interface, a CPU, a memory, and the like (not shown). Further, in the memory of the ECU 40, as a software, a cold state determining unit (cold state determining unit) 41, a start determining unit (starting determination unit) 42, a valve opening period changing unit (intake valve opening period changing unit, intake air) Valve control means) 43 and phase change unit (intake valve characteristic phase change means, intake valve control means) 44 are recorded.

Among these, the cooling state determination unit 41 determines that the engine 11 is in a warm state when the cooling water temperature WT of the engine 11 obtained by the cooling water temperature sensor 39 is larger than the threshold water temperature WT _TH , and the cooling water temperature WT. There is smaller than the threshold temperature WT _TH is to determine that the engine 11 is cold state.
The start determination unit 42 determines that the engine 11 is starting when the engine 11 is cranked by the starter motor 27 and does not rely on the starter motor 27 and the engine 11 spontaneously When the vehicle is operating, it is determined that the engine 11 has been started.

Further, the start determination unit 42 can determine whether or not the engine 11 is idling by detecting on / off of an idle switch (not shown).
Open period changing unit 43 controls the inlet valve opening term varying mechanism 31 changes the valve opening period T _IO of inlet valve 21, and controls an inlet valve opening term varying mechanism 31.
More specifically, as shown in FIG. 2, the open period changing unit 43, when that engine 11 'cold-a and and during start-up', opening term T _IO "a first intake valve 21 The intake period _TIO1 "is set.

Also, the open period changing unit 43, when that engine 11 'cold-a and and idling after completion of startup', sets the opening term T _IO of inlet valve 21 to "second intake period T _IO2" It is supposed to be.
Furthermore, the opening period changing unit 43 sets referred engine 11 'is warm state and idle after completion of startup', the opening term T _IO of inlet valve 21 to "third intake period T _IO3" It is supposed to be.

Here, the first intake period T _IO1 is, | 230 ° | [CA ( Crankshaft Angle; crankshaft angle) is set to a degree, the second intake period T _IO2 is, | is set to [CA] degree | 250 ° Further, the third intake period _TIO3 is set to about | 270 ° | [CA].
.
That is, the valve opening period changing unit 43, so that the relationship of the following formula (1) is satisfied, so as to set a first intake period T _IO1 and second intake period T _IO2 and third inlet period T _IO3 ing.

T _IO1 <T _IO2 <T _IO3 (1)
Moreover, the IO opening timing of the intake valve 21 in the first intake period T _IO1 called IO ₁ first intake valve opening timing, the valve opening end timing IC first of intake valve closing timing IC _1.
Moreover, the IO opening timing of the intake valve 21 in the second intake period T _IO2 called second intake valve opening timing IO _2, the closing timing IC of the second intake valve closing timing IC _2.

Moreover, the opening timing IO of the intake valve 21 in the third intake period T _IO3 called third intake valve opening timing IO _3, the closing timing IC of the third intake valve closing timing IC _3.
Then, the valve opening period changing unit 43 sets the first intake period T _IO1 , the second intake period T _IO2, and the relationship so that the relations of the following expressions (2) and (3) are established with reference to the order of early crank angle: The third intake period _TIO3 is set respectively.

IO ₃ <IO ₂ <IO ₁ (2)
IC ₁ <IC ₂ <IC ₃ (3)
Further, the valve opening period changing unit 43 sets the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ to be in the first half of the compression stroke. A period _TIO1 , a second intake period _TIO2 and a third intake period _TIO3 are set.

Further, the valve opening period changing unit 43 can adjust a period during which both the intake valve 21 and the exhaust valve 22 of the engine 11 are open (valve overlap (VOL: Valve OverLap) period). ing.
More specifically, the valve opening period changing unit 43 sets the valve overlap period VOL to the first valve overlap period VOL ₁ when the engine 11 is “cold and starting”. ing.

Further, the valve opening period changing unit 43 sets the valve overlap period VOL to the second valve overlap period VOL ₂ when the engine 11 is “cold and idling after the start is completed”. It has become.
At this time, the valve opening period changing unit 43 performs the first intake period T T so that the first valve overlap period VOL ₁ is shorter than the second valve overlap period VOL _{2 as} shown in the following equation (4). _IO1 and the second intake period _TIO2 are set.

VOL ₁ <VOL ₂ (4)
Further, the valve opening period changing unit 43 causes the valve opening timing IO ₁ of the intake valve 21 to be later than the valve closing timing EC ₁ of the exhaust valve 22 when the engine 11 is “cold and starting”. By setting to, the negative first valve overlap period VOL ₁ may be set. In this way, the valve overlap period VOL set to minus is referred to as negative overlap.

On the other hand, the valve opening period changing unit 43 determines that the opening timing IO ₂ of the intake valve 21 is higher than the closing timing EC ₂ of the exhaust valve 22 when the engine 11 is “cold and idle after completion of starting”. By setting so as to be faster, the second valve overlap period VOL ₂ is made positive.
Further, when the engine 11 is “cold and idling after completion of starting”, the valve opening period changing unit 43 increases the coolant temperature WT obtained by the coolant temperature sensor 39 as the coolant temperature WT increases. so as to retard the 2 intake valve closing timing IC _2, it is adapted to correct the second intake period T _IO2.

As shown in FIG. 2, the phase changing unit 44 _omits all the phases P _IO1 , P _IO2 , P _IO3 of the intake valve lift lines L _IO1 , L _IO2 , L _IO3 without controlling the intake characteristic phase changing mechanism 32. These phases are matched so that all of these phases _PIO1 , _PIO2 , and _PIO3 are in the latter half of the intake stroke.
Incidentally, the phase P _IO of the first valve lift line L _IO1 referred to as a first intake phase P _IO1, it refers to a phase P _IO of the second valve lift line L _IO2 and second intake phase P _IO2, The third valve lift the phase P _IO line L _IO3 that third intake phase P _IO3.

Since the engine control apparatus according to an embodiment of the present invention is configured as described above, the following operations and effects are achieved.
As shown in step S11 in FIG. 3, cold determination unit 41, when the when the cooling water temperature WT of the engine 11 obtained by the cooling water temperature sensor 39 is greater than the threshold temperature WT _TH engine 11 is a temperature state On the other hand, if the cooling water temperature WT is equal to or lower than the threshold water temperature WT _TH, it is determined that the engine 11 is in a cold state (Yes route in step S11).

Here, when it is determined that the engine 11 is cold (Yes route of step S11), the start determination unit 42 determines whether or not the engine 11 is being started by the starter motor 27 (step S11). S12).
Then, if the engine 11 is determined to be being started (Yes route in step S12), the valve opening period changing unit 43, upon setting the first intake valve closing timing IC ₁ (step S13), and The first intake valve opening period _TIO1 is changed (step S14).

On the other hand, when it is determined that the engine 11 is not being started (No route of step S12), the start determination unit 42 further determines whether or not the engine 11 is idling after the start is completed (step S15). ).
Here, when the engine 11 is determined to be idle after completion of starting (Yes route in step S15), and the opening period changing unit 43, after setting the second intake valve closing timing IC ₂ (Step S16), the second intake period _TIO2 is changed (step S17).

At this time, the valve opening period changing unit 43, as the cooling water temperature WT obtained by the cooling water temperature sensor 39 becomes higher, corrected retarding the second intake valve closing timing IC ₂ (step S16).
When the cold state determination unit 41 determines that the engine 11 is hot (No route of step S11), the valve opening period change unit 43 determines whether or not the engine 11 is idling ( Step S18).

Here, when the engine 11 is determined to be idle (Yes route in step S18), and the opening period changing unit 43, after setting the third intake valve closing timing IC ₃ (step S19), the 3. The intake valve opening period _TIO3 is changed (step S20).
Note that when the start of the cold engine 11 is completed but not idle (No route in step S15), or when the warm engine 11 is not idle (No route in step S18), the present invention. Since the engine 11 is controlled by a control logic different from the above, in the flowchart shown in FIG.

As described above, the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ set in steps S13, S16, and S19 are respectively expressed by the above equation (3). To meet the relationship.
As a result, the first intake valve closing timing IC ₁ is advanced from the second intake valve closing timing IC ₂ so that the engine 11 can be started quickly even when the engine 11 is cold. .

That is, even when the engine 11 is in a cold state, the pressure in the combustion chamber 15 can be sufficiently increased, and reliable ignition can be achieved.
And by improving ignitability, the fuel required for the engine 11 start-up can be reduced, and the discharge | emission of the unburned fuel accompanying a start can be suppressed.
Further, after the start of the engine 11 is completed, the valve closing timing IC of the intake valve 21 is delayed, that is, the second intake valve closing timing IC ₂ is delayed from the first intake valve closing timing IC _1. Therefore, after the start of the engine 11 is completed, the increase in pressure in the combustion chamber 15 is suppressed, so that combustion noise and vibration can be suppressed, and the structural strength of the engine 11 can be made higher than before. It can also be reduced, and the weight reduction of the engine 11 can be promoted.

Furthermore, by reducing the weight of the piston and reducing the compression pressure, the frictional force between the piston and cylinder, the crank, and the connecting rod can be reduced and friction can be reduced.
Furthermore, the discharge of nitrogen oxide (NOx) contained in the exhaust gas can be suppressed by not setting the combustion chamber 15 in an excessively high temperature and high pressure state.
In addition, since stable combustion is obtained, the temperature of the engine 11 can be quickly raised, the warm-up idle period can be shortened, and the fuel efficiency and exhaust gas performance can be improved.

Also, by making the first valve overlap period VOL ₁ shorter than the second valve overlap period VOL ₂ , fuel blow-off to the exhaust side is suppressed and the internal EGR gas amount is reduced to improve combustion efficiency. The combustion in the first and subsequent explosions, which are usually unstable, is improved, and the transition from the first explosion to the state in which the explosion continues smoothly can be made, and the engine speed can be increased smoothly.

Here, the operation and effect of the present invention of the present embodiment will be described with reference to FIGS.
As shown in FIG. 4 (A), at the time of cold start of the engine, conventionally, the valve closing timing IC of the intake valve is generally constant (see line La). In contrast, in the present invention according to the present embodiment, when the engine 11 is cold started, the closing timing IC of the intake valve 21 is advanced more than in the past (see line Lb).

In this case, as shown by a line Ld in FIG. 4B, the engine speed NE cannot be increased easily by the conventional technique (see arrow A2), but as shown by a line Lc, According to the present invention, it is possible to quickly complete the first explosion, shift to a state in which the explosion continues smoothly, and quickly increase the engine speed NE (see arrow A1).
As a result, as shown by a line Le in FIG. 4C, in the prior art, a relatively large amount of unburned fuel (that is, hydrocarbon (HC) component) is contained in the exhaust gas. As indicated by line Lf, according to the present invention related to the present embodiment, the exhaust gas performance can be improved by suppressing the amount of unburned fuel contained in the exhaust gas.

Furthermore, it is possible to quickly end the operation at the warm-up idle speed set as a relatively high speed and shift to the normal idling speed (see arrow A3), thereby improving fuel consumption and exhaust gas performance. Can contribute.
Next, an engine control apparatus according to a reference embodiment will be described.
FIG. 5 is a schematic block diagram showing the overall configuration, FIG. 6 is a schematic valve lift diagram showing the valve lift characteristics, and FIG. 7 is a schematic flowchart showing the control contents.

In addition, the same code | symbol is attached | subjected about the component same as one above-mentioned embodiment, the description is abbreviate | omitted, and it demonstrates focusing on difference with one embodiment here. In some cases, using a diagram used for explaining the above-described embodiment.
While in one embodiment described with reference to FIG. 1 was embodiment that preferentially controls the opening period changing unit 43, in this reference embodiment, the valve opening period changing unit 53 and the phase change shown in FIG. 5 In the part 54, the form which controls the phase change part 54 preferentially is shown. In addition, about components other than these valve opening period change part 53 and phase change part 54, it is the same as that of one Embodiment.

Open period changing unit 53, according to the operating state of the engine 11, in which controlling the inlet valve opening term varying mechanism 31 changes the valve opening period T _IO of the intake valve 21.
As is the case with one embodiment, it refers to the opening term T _IO of inlet valve 21 when engine 11 is 'cold-a and and during start-up' and the first opening term T _IO1, the engine 11 is in the opening term T _IO of inlet valve 21 when a 'cold-a and and idling after completion of startup' called second opening term T _IO2, the engine 11 'is warm state and idle' the opening term T _IO of inlet valve 21 is referred third opening term T _IO3.

However, as shown in FIG. 6 and the following equation (5), the valve opening period changing unit 53 is configured to use any of the first valve opening period _TIO1 , the second valve opening period _TIO2, and the third valve opening period _TIO3 . Are set to be equal periods.
T _IO1 = T _IO2 = T _IO3 (5)
The phase changing unit 54 sets the first intake valve lift line L _IO1 to the first intake phase P _IO1 when the engine 11 is “cold and starting”, and the engine 11 is “cold and started”. 'the second intake valve lift line L _IO2 is set in the second intake phase P _IO2 if that, the engine 11' idle after completing the third intake if that is warm state and idle after completion of startup ' the valve lift line L _IO3 is adapted to set the third intake phase P _IO3.

Here, the first intake phase P _IO1 is | [CA (Crankshaft Angle; crankshaft angle)] | 80 ° is about, the second intake phase P _IO2 is | 110 ° | a [CA] C., further, the The third intake phase _PIO3 is about | 140 ° | [CA].
Further, the phase change unit 54, the first intake phase PIO1, the second intake phase P _IO2 and third inlet phase P _IO3 is so set as to satisfy the equation (6) below. In addition, this Formula (6) is the same as Formula (3) in one Embodiment.

IC ₁ <IC ₂ <IC ₃ (5)
Further, the phase change unit 54, the first intake valve lift line L _IO1 of the first intake phase P _IO1 set, the second intake valve lift line L _IO2 of the second intake phase P _IO2, or third intake phase P _The intake characteristic phase changing mechanism 32 is controlled so that the intake valve 21 operates according to the third intake valve lift line _{LIO3 of IO3} .

Further, the phase changing unit 54 controls the first intake phase P so that the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ are in the first half of the compression stroke. _IO1 , the second intake phase _PIO2, and the third intake phase _PIO3 are set.
Further, the phase changing unit 54 can adjust the valve overlap period.

More specifically, the phase changing unit 54 sets the valve overlap period VOL to the first valve overlap period VOL ₁ shown in FIG. 6 when the engine 11 is “cold and starting”. It has become.
Further, the phase change unit 54 sets the valve overlap period VOL to the second valve overlap period VOL ₂ shown in FIG. 6 when the engine 11 is “cold and idling after completion of starting”. It is like that.

In this case, the phase changing portion 54, as shown by the following formula (7), such that the first valve overlap period VOL ₁ is longer than the second valve overlap period VOL _2, first intake phase P _IO1 and The second intake phase _PIO2 is set. In other words, the phase changing unit 54 establishes a reverse relationship to the above equation (4).
VOL ₁ > VOL ₂ (7)
The phase changing unit 54 is set so that the opening timing IO ₁ of the intake valve 21 is earlier than the closing timing EC ₁ of the exhaust valve 22 when the engine 11 is “cold and starting”. Thus, the positive first valve overlap period VOL ₁ is set.

Furthermore, when the engine 11 is “cold and idling after completion of the start”, the phase change unit 54 determines that the opening timing IO ₂ of the intake valve 21 is earlier than the closing timing EC ₂ of the exhaust valve 22. By setting so as to be, a positive second valve overlap period VOL ₂ is set. That is, the first valve overlap period VOL ₁ and the second valve overlap period VOL ₂ in this embodiment are both positive overlaps.

Further, when the engine 11 is “cold and idling after completion of starting”, the phase changing unit 54 increases the second intake air as the cooling water temperature WT obtained by the cooling water temperature sensor 39 increases. as to retard the closing timing IC _2, it is adapted to correct the second intake phase P _IO2.
Since the engine control apparatus according to the reference embodiment is configured as described above, the following operations and effects are achieved.

As shown in FIG. 7, in step S31, cold determination unit 41, the engine 11 is in a warm state when greater than the cooling water temperature WT is the threshold temperature WT _TH of the engine 11 obtained by the cooling water temperature sensor 39 determines that (No route in step S31), on the other hand, when the cooling water temperature WT is lower than the threshold temperature WT _TH determines that the engine 11 is cold-(Yes route of step S31).

Here, when it is determined that the engine 11 is cold (Yes route of step S31), the start determination unit 42 determines whether or not the engine 11 is being started by the starter motor 27 (step S31). S32).
Here, when it is determined that the engine 11 is being started (Yes route of step S32), the phase changing unit 54 sets the first intake valve closing timing IC ₁ (step S33), and then One intake phase _PIO1 is changed (step S34).

On the other hand, when it is determined that the engine 11 is not being started (No route of step 32), the start determination unit 42 further determines whether or not the engine 11 is idling after the start is completed (step S35). ).
Here, when the engine 11 is determined to be idle after completion of starting (Yes route in step S35), the phase change unit 54, after setting the second intake valve closing timing IC ₂ (Step S36) Then, the second intake phase _PIO2 is changed (step S37).

In this case, the phase changing portion 54, as the cooling water temperature WT obtained by the cooling water temperature sensor 39 becomes higher, corrected retarding the second intake valve closing timing IC ₂ (step S36).
When the cold state determination unit 41 determines that the engine 11 is hot (No route of step S31), the start determination unit 42 determines whether or not the engine 11 is idle (step S38). ).

Here, when the engine 11 is determined to be idle (Yes route of step S38), the phase changing portion 54, after setting the third intake valve closing timing IC ₃ (step S39), the third intake The phase _PIO3 is changed (step S40).
If the cold engine 11 has been started but not idle (No route in step S35), or if the engine 11 in the warm operation is not idle (No route in step S38), Since the engine 11 is controlled by a control logic different from that of the invention, in the flowchart shown in FIG. 7, the requested output is output in a suitable operating state through a return.

As described above, the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ set in steps S33, S36, and S39 are the above-described equations (5), respectively. To meet the relationship.
That is, the first intake valve closing timing IC ₁ is advanced from the second intake valve closing timing IC ₂ so that the engine 11 can be started quickly even when the engine 11 is in a cold state.

That is, when the engine 11 is cold, the engine oil viscosity is high, so that it is difficult to increase the cranking rotation speed by the starter motor 27, but the pressure in the combustion chamber 15 can be sufficiently increased. It can be made possible.
Further, by improving the ignitability, it is possible to suppress the discharge of unburned fuel accompanying the start failure of the engine 11 and to reduce the fuel required for starting the engine 11.

Further, after the start of the engine 11 is completed, the valve closing timing IC of the intake valve 21 is delayed, that is, the second intake valve closing timing IC ₂ is delayed from the first intake valve closing timing IC _1. Therefore, after the start of the engine 11 is completed, it is possible to suppress a situation in which the pressure in the combustion chamber 15 increases excessively, and noise and vibration can be suppressed, and the structure of the engine 11 can be suppressed. The strength can be reduced as compared with the conventional case, and the weight reduction of the engine 11 can be promoted. Furthermore, the sliding frictional force between the piston and the cylinder, the crank and the connecting rod is reduced by reducing the weight of the piston and reducing the compression pressure, and the friction of the engine 11 can be reduced.

Furthermore, the amount of nitrogen oxide (NOx) contained in the exhaust gas can be suppressed by not setting the combustion chamber 15 in an excessively high temperature and high pressure state.
In addition, since stable combustion can be obtained, the temperature of the engine 11 can be quickly raised, and the period during which the engine 11 is operated at the cold idle speed set as a relatively high speed can be shortened. It is possible to contribute to improvement of fuel consumption and exhaust gas performance.

Further, as shown in the above equation (7), the valve overlap period (that is, the first valve overlap period VOL ₁ ) when the cold engine 11 is being started is determined during the start of the cold engine 11. valve overlap period when the completed (i.e., the second valve overlap period VOL ₂₎ to be longer than, by setting the first intake phase P _IO1 and the second intake phase P _IO2, the intake valve 21 When the engine is opened, the combustion gas containing a large amount of unburned gas or the unburned gas that has not been ignited is taken into the intake port 24 of the engine 11 and re-inhaled into the combustion chamber to raise the temperature in the combustion chamber. It is possible to prepare an environment that is easy to burn, and shift the incomplete combustion state of the first explosion to a state where the explosion continues smoothly. Thus, although the reverse can correspond to the one embodiment for the corresponding valve overlap period, which varies depending on the fuel properties and ignition system (spark ignition or compression ignition).

Also in the present invention of this embodiment, FIG. 4 (A) ~ (C) can be obtained substantially the same effects as in the embodiment as shown and described in.
Next, an engine control apparatus according to another reference embodiment will be described. The technical idea of this embodiment is a combination of the above-described one embodiment and the reference embodiment.
8 is a schematic block diagram showing the overall configuration, FIG. 9 is a schematic valve lift diagram showing the valve lift characteristics, and FIG. 10 is a schematic flowchart showing the control contents.

In addition, the same code | symbol is attached | subjected about the component same as one embodiment mentioned above and reference embodiment , the description is abbreviate | omitted, and it demonstrates focusing on the difference with one embodiment and reference embodiment here. To do. In some cases, using a diagram used for explaining an embodiment and reference embodiment described above.
In the present embodiment, the opening period changing unit 63 and the phase changing portion 64 shown in FIG. 8 is provided instead of the opening period changing unit 43 and the phase changing portion 44 in the embodiment described with reference to FIG. 1 ing. In other words, for these open period changing unit 63 and components other than the phase changing portion 64 is the same as the embodiment. Therefore, here, the valve opening period changing unit 63 and the phase changing unit 64 will be mainly described.

Open period changing unit 63, according to the operating state of the engine 11, in which controlling the inlet valve opening term varying mechanism 31 changes the valve opening period T _IO of the intake valve 21.
More specifically, as shown in FIG. 9, the opening period changing unit 63 'is cold-and during a start' engine 11 may be referred to as "first valve opening period T _IO of the intake valve 21 The intake period _TIO1 "is set.

Also, the open period changing unit 63, when that engine 11 'cold-a and and idling after completion of startup', the opening term T _IO of inlet valve 21 shown in FIG. 9, "the second intake period T " _IO2 " is set.
Furthermore, the opening period changing unit 63 sets referred engine 11 'is warm state and idle after completion of startup', the opening term T _IO of inlet valve 21 to "third intake period T _IO3" It is supposed to be.

Here, the first intake period _TIO1 is set to about | 230 ° | [CA], the second intake period _TIO2 is set to about | 250 ° | [CA], and further the third intake period T _IO3 is set to about | 270 ° | [CA].
Then, as shown in FIG. 9 and the following equation (8), the opening period changing unit 63, than the first opening period T _IO1 longer second opening term T _IO2, and, second opening period The third valve opening period _TIO3 is set longer than _TIO2 . This equation (8) is the same as the above equation (1).

T _IO1 <T _IO2 <T _IO3 (8)
The phase changing unit 64 sets the first intake valve lift line L _IO1 to “first intake phase P _IO1 ” when the engine 11 is “cold and starting”, and the engine 11 is “cold”. In the case of “idle after start-up”, the second intake valve lift line L _IO2 is set to “second intake phase P _IO2 ” and the engine 11 is “warm and idle after start-up”. The third intake valve lift line L _IO3 is set to “third intake phase P _IO3 ”.

Here, the first intake phase _PIO1 is about | 110 ° | [CA], the second intake phase _PIO2 is about | 125 ° | [CA], and the third intake phase _PIO3 is | It is about 140 ° | [CA].
Then, the valve opening period changing unit 63 and the phase changing unit 64 have the first to third intake valve opening periods T so as to satisfy the following formulas (9) and (10) based on the order of early crank angle. _IO1 , _TIO2 , _TIO3 and first to third intake phases _PIO1 , _PIO2 , _PIO3 are set.

IO ₃ <IO ₂ <IO ₁ or IO ₁ = IO ₂ = IO ₃ (9)
IC ₁ <IC ₂ <IC ₃ (10)
The equation (10) is the same as the above equations (3) and (5).
Further, the phase changing unit 64 is such that all of the first to third intake valve opening timings IO ₁ , IO ₂ , IO ₃ are at the top dead center of the intake stroke (that is, 0 ° [CA]). The first to third intake phases _PIO1 , _PIO2 , and _PIO3 are set.

Further, the valve opening period changing unit 63 and the phase changing portion 64, a first intake valve lift line L _IO1 of the first open period T _IO1 and the first intake phase P _IO1 set, the second valve opening period T set _IO2 and the second intake phase P _IO2 of the second intake valve lift line L _IO2 or the intake valve 21 is actuated in accordance with the third intake valve lift line L _IO3 of the third opening period T _IO3 and third intake phase P _IO3 set Thus, the intake valve opening period changing mechanism 31 and the intake characteristic phase changing mechanism 32 are controlled.

In other words, the phase changing unit 64 sets the first intake phase P so that the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ are in the first half of the compression stroke. _IO1 , the second intake phase _PIO2, and the third intake phase _PIO3 are set.
Further, the valve opening period changing unit 63 and the phase changing unit 64 can adjust the valve overlap period VOL.

More specifically, the valve opening period changing unit 63 and the phase changing unit 64 show the valve overlap period VOL in FIG. 2 or FIG. 9 when the engine 11 is “cold and starting”. The first valve overlap period VOL ₁ is set.
Further, the valve opening period change unit 63 and the phase change unit 64 indicate the valve overlap period VOL in FIG. 2 or FIG. 9 when the engine 11 is “cold and idling after completion of starting”. The second valve overlap period VOL ₂ is shown.

In the present embodiment, since the effect on the valve overlap shown in FIG. 2 is as described above, the first valve overlap period VOL ₁ and the second valve overlap period are expressed by the following equation (11). Reference is made to FIG. 9 where VOL ₂ is zero.
VOL ₁ = VOL ₂ = 0 (11)
Further, the valve opening period change unit 63 and the phase change unit 64 increase the cooling water temperature WT obtained by the cooling water temperature sensor 39 when the engine 11 is “cold and idle after completion of starting”. take, as to retard the second intake valve closing timing IC _2, is adapted to correct the second opening term T _IO2 and the second intake phase P _IO2 to.

Since the engine control apparatus according to another reference embodiment is configured as described above, the following operations and effects are achieved.
As shown in FIG. 10, in step S51, cold determination unit 41, the engine 11 is in a warm state when greater than the cooling water temperature WT is the threshold temperature WT _TH of the engine 11 obtained by the cooling water temperature sensor 39 determines that (No route in step S51), on the other hand, when the cooling water temperature WT is lower than the threshold temperature WT _TH determines that the engine 11 is cold-(Yes route of step S51).

Here, when it is determined that the engine 11 is cold (Yes route of step S51), the start determination unit 42 determines whether or not the engine 11 is being started by the starter motor 27 (step S51). S52).
Here, when the engine 11 is determined to be being started (Yes route in step S52), the valve opening period changing unit 63 and the phase changing portion 64, upon setting the first intake valve closing timing IC ₁ ( In step S53, the first intake valve opening period _TIO1 and the first intake phase _PIO1 are changed (step S54).

On the other hand, when it is determined that the engine 11 is not being started (No route of step 52), the start determination unit 42 further determines whether or not the engine 11 is idling after the start is completed (step S55). ).
Here, (Yes route of step S55), the valve opening period changing unit 63 and the phase changing portion 64 when the engine 11 is determined to be idle after starting is completed, sets the second intake valve closing timing IC ₂ It was over in that (step S56), and changes the second inlet valve opening term T _{IO 2} and the second intake phase P _{IO 2} (step S57).

At this time, the valve opening period changing unit 63 and the phase changing unit 64 correct the retardation of the second intake valve closing timing IC ₂ as the cooling water temperature WT obtained by the cooling water temperature sensor 39 becomes higher (step). S56).
When the cold state determination unit 41 determines that the engine 11 is hot (No route of step S51), the start determination unit 42 determines whether or not the engine 11 is idle (step S58). ).

Here, when the engine 11 is determined to be idle (Yes route of step S58), the phase changing portion 54, after setting the third intake valve closing timing IC ₃ (step S59), the third intake The valve opening period _TIO3 and the third intake phase _PIO3 are changed (step S60).
Note that when the start of the cold engine 11 is completed but not idle (No route of step S55), or when the engine 11 during the warm operation is not idle (No route of step S58), this Since the engine 11 is controlled by a control logic different from that of the invention, in the flowchart shown in FIG. 10, the requested output is output in a suitable operating state through a return.

Thus, the first intake valve closing timing IC ₁ , the second intake valve closing timing IC _2, and the third intake valve closing timing IC ₃ set in steps S53, S56, and S59 are the above-described equations (10), respectively. To meet the relationship.
As a result, the first intake valve closing timing IC ₁ is advanced from the second intake valve closing timing IC ₂ so that the engine 11 can be started quickly even when the engine 11 is cold. .

That is, when the engine 11 is in the cold state, the cranking rotation speed by the starter motor 27 is difficult to increase because the viscosity of the engine oil is high, but the pressure in the combustion chamber 15 can be sufficiently increased, so that reliable ignition is possible. Can be made possible.
Further, by improving the ignitability, it is possible to suppress the discharge of unburned fuel accompanying the start failure of the engine 11 and to reduce the fuel required for starting the engine 11.

Further, after the start of the engine 11 is completed, the valve closing timing IC of the intake valve 21 is delayed, that is, the second intake valve closing timing IC ₂ is delayed from the first intake valve closing timing IC _1. Therefore, after the start of the engine 11 is completed, it is possible to suppress a situation in which the pressure in the combustion chamber 15 increases excessively, and noise and vibration can be suppressed, and the structure of the engine 11 can be suppressed. The strength can be reduced as compared with the conventional case, and the weight reduction of the engine 11 can be promoted. Furthermore, the sliding frictional force between the piston and the cylinder, the crank and the connecting rod is reduced by reducing the weight of the piston and reducing the compression pressure, and the friction of the engine 11 can be reduced.

Furthermore, the amount of nitrogen oxide (NOx) contained in the exhaust gas can be suppressed by not setting the combustion chamber 15 in an excessively high temperature and high pressure state.
In addition, since stable combustion can be obtained, the temperature of the engine 11 can be quickly raised, and the period during which the engine 11 is operated at the cold idle speed set as a relatively high speed can be shortened. It is possible to contribute to improvement of fuel consumption and exhaust gas performance.

Further, as shown in the above equation (11), the valve overlap period when the cold engine 11 is being started (that is, the first valve overlap period VOL ₁ ), and the cold engine 11 is started. By setting both the valve overlap period (that is, the second valve overlap period VOL ₂ ) in the case of completion to zero, it is possible to suppress the blow-through of fuel to the exhaust port due to the overlap.

Incidentally, Oite the present type state also, FIG. 4 (A) ~ (C) can be obtained substantially the same effects as in the embodiment as shown and described in.
As mentioned above, although one embodiment and reference embodiment of this invention were described, this invention is not limited to this embodiment, It can implement in various deformation | transformation in the range which does not deviate from the meaning of this invention. An example is shown below.

In the above-described embodiment, the case where the engine 11 is a spark ignition engine, for example, a gasoline engine has been described as an example. However, an engine that performs compression ignition, for example, a diesel engine may be used.
In the above-described embodiment, the case where the second intake valve closing timing IC ₂ is corrected based on the cooling water temperature WT detected by the cooling water temperature sensor 39 has been described as an example. However, the present invention is not limited thereto. It is not a thing. For example, an intake air temperature sensor (intake air temperature acquisition means) for detecting the intake air temperature of the engine 11 is provided, and the second intake valve closing timing IC ₂ is corrected based on the intake air temperature detected by the intake air temperature sensor. Good.

  In the above-described embodiment, the case where the valve opening period and the phase of the exhaust valve are not changed has been described. However, the present invention is not limited to this, and the exhaust valve may be appropriately controlled.

1 is a schematic block diagram showing an overall configuration of an engine control apparatus according to an embodiment of the present invention. It is a typical valve lift diagram which shows the valve lift characteristic of the intake valve and exhaust valve which are driven by the engine control apparatus which concerns on one Embodiment of this invention. It is a typical flowchart which shows the control content of the control apparatus of the engine which concerns on one Embodiment of this invention. It is a typical time chart which shows the effect by the control device of the engine concerning one embodiment of the present invention. It is a typical block diagram which shows the whole structure of the control apparatus of the engine which concerns on reference embodiment. It is a typical valve lift diagram which shows the valve lift characteristic of the intake valve and exhaust valve which are driven by the control device for the engine according to the reference embodiment. It is a typical flowchart which shows the control content of the control apparatus of the engine which concerns on other reference embodiment. It is a typical block diagram which shows the whole structure of the control apparatus of the engine which concerns on other reference embodiment. It is a typical valve lift diagram which shows the valve lift characteristic of the intake valve and exhaust valve which are driven by the control device of the engine according to another reference embodiment. It is a typical flowchart which shows the control content of the control apparatus of the engine which concerns on other reference embodiment.

Explanation of symbols

10 Vehicle 11 Reciprocating gasoline engine (engine)
21 Intake valve 22 Exhaust valve 33 Intake variable valve mechanism (variable valve mechanism)
34 Exhaust variable valve mechanism (variable valve mechanism)
39 Cooling water temperature sensor (engine temperature detection means)
41 Cold determination unit (cool determination unit)
42 Start determination unit (start determination means)
43, 53, 63 Valve opening period changing section (intake valve opening period changing means; intake valve control means)
44, 54, 64 Phase change unit (intake valve characteristic phase change means; intake valve control means)
IO Inlet valve opening timing EO Exhaust valve opening timing IC Inlet valve closing timing EC Exhaust valve closing timing VOL ₁ First valve overlap period VOL ₂ Second valve overlap period L _IO Intake valve opening and closing Valve characteristics Phase of _PIO intake valve opening and closing characteristics

Claims (6)

Cold state determining means for determining whether or not the engine mounted on the vehicle is cold;
Start determination means for determining whether the engine is starting or idle after completion of starting;
A variable valve mechanism that drives the intake valve of the engine while at least changing the valve closing timing;
An intake valve control means for controlling the closing timing of the intake valve using the variable valve mechanism;
The intake valve control means includes:
A first intake valve closing timing that is a closing timing of the intake valve when the cold state determining means determines that the engine is cold and the start determining means determines that the engine is starting. Is set during the compression stroke to increase the pressure in the combustion chamber,
A second timing that is the closing timing of the intake valve when the cold state determining means determines that the engine is cold and the start determining means determines that the engine has been started and is idle . Setting the intake valve closing timing to be retarded from the first intake valve closing timing during the compression stroke, and suppressing the pressure rise in the combustion chamber ;
The variable valve mechanism can further change the valve opening period of the intake valve,
The intake valve control means includes:
When the cold state determining means determines that the engine is cold and the start determining means determines that the engine is starting, both the exhaust valve and the intake valve of the engine are opened. A first valve overlap period, which is a period during which the engine is cold, is determined by the cold state determination means and the start determination means determines that the engine has been started and is idle. An opening period of the intake valve is changed so as to be shorter than a second valve overlap period in which both the exhaust valve and the intake valve are open. Control device . Engine temperature detecting means for detecting the temperature of the engine,
The intake valve control means includes:
The second intake valve closing timing is corrected according to the engine temperature acquired by the engine temperature detection means when the cold determination means determines that the engine is cold, The engine control device according to claim 1 . An intake air temperature detecting means for detecting the intake air temperature of the engine;
The intake valve control means includes:
When it is determined by the cold determination means that the engine is cold, the second intake valve closing timing is corrected according to the intake air temperature acquired by the intake air temperature acquisition means, The engine control device according to claim 1 . The intake valve control means includes:
The engine control device according to claim 2 , wherein the second intake valve closing timing is retarded as the engine temperature acquired by the engine temperature acquisition means increases. The intake valve control means includes:
4. The engine control device according to claim 3 , wherein the second intake valve closing timing is retarded as the intake air temperature acquired by the intake air temperature acquisition means increases. Movable variable valve mechanism, and changes the opening period of the intake valve continuously, the control device for an engine according to claim 1 to 5 any one.

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