JP2001280228A - Ignition timing control device for variable valve engine - Google Patents

Abstract

(57) [Problem] To optimally set an ignition timing when performing a non-throttle operation by controlling an intake air amount by controlling a valve timing of an intake valve and an exhaust valve. An engine speed Ne and a target air amount TQ are provided.
The basic ignition timing ADV at the valve timing of the base (during throttle operation) is set according to (S1). In accordance with the intake valve closing timing IVC, the correction amount H is set so that the ignition timing is advanced as the effective compression ratio becomes smaller due to the change.
OS1 is set (S2). The correction amount HOS2 is set such that the earlier the intake valve opening timing IVO, the more the ignition timing is advanced (S3). In accordance with the exhaust valve closing timing EVC, the correction amount HOS3 is set so that the ignition timing is advanced as the distance from TDC increases (S4). The basic ignition timing MADV is corrected by the correction amounts HOS1 to HOS3 to determine the ignition timing ADV (S5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-throttle operation by controlling a valve timing by controlling a valve timing so as to control an intake air amount by controlling a valve timing of an intake valve and an exhaust valve. The present invention relates to an ignition timing control device for optimally controlling the ignition timing in a variable valve engine that performs the following.

[0002]

2. Description of the Related Art Conventionally, as shown in Japanese Patent Application Laid-Open No. 8-2000025, a variable valve operating device, for example, an electromagnetic drive device is used to drive an intake valve and an exhaust valve, and the opening and closing operation of these valves is optional. There are some that can be controlled.

In particular, in the variable valve engine described in the above publication, two main and auxiliary intake valves and two exhaust valves provided for each cylinder are electromagnetically driven and operated in different combinations according to engine operating conditions. Output control.

Further, in recent years, in order to improve fuel efficiency by reducing pump loss, instead of ordinary throttle operation, the intake air amount is controlled by controlling the valve timing of intake valves and exhaust valves, particularly the intake valve closing timing. Attention has been paid to those that perform non-throttle operation, and their development is being promoted.

[0005]

In a conventional general ignition timing control system for an engine, the ignition timing is set according to the engine speed and the load (torque).

On the other hand, when the above-described non-throttle operation is performed, the intake valve is closed so as to achieve the target air amount (target cylinder intake air amount) corresponding to the target torque determined by the engine operating conditions. The timing is set and controlled. Even if the target torque is the same, the intake valve closing timing fluctuates due to the target boost or the like.

[0007] Also, valve overlap (intake valve opening timing, exhaust valve closing timing) of the intake valve and the exhaust valve also fluctuates depending on the target internal EGR rate and the like. Therefore, the closing timing of the intake valve and the valve overlap are not uniquely determined according to the target torque.

For this reason, even if the ignition timing is controlled in accordance with the engine speed and the load (torque), the optimum ignition timing cannot be obtained due to the fluctuation of the intake valve closing timing or the valve overlap, and the fuel consumption and operation However, there is a problem that the property is deteriorated.

That is, when the intake valve closing timing is advanced, the effective compression ratio is reduced and the combustion speed is reduced, so that the required ignition timing is advanced. However, in the conventional ignition timing control, the intake valve closing timing is considered. Therefore, it was not possible to control the ignition timing to the optimum.

Also, when controlling the internal EGR rate (residual gas rate) by controlling the valve overlap, if the internal EGR rate increases, the combustion speed decreases, so that the required ignition timing is advanced. In the ignition timing control, since the valve overlap was not taken into consideration, it was not possible to control the ignition timing to the optimum.

In view of the above problems, the present invention can improve fuel efficiency and drivability by optimizing the ignition timing in consideration of valve timing in non-throttle operation. It is an object to provide an ignition timing control device for a variable valve engine.

[0012]

According to the first aspect of the present invention, there is provided a variable valve operating device capable of arbitrarily controlling the valve timing of an intake valve and an exhaust valve, and controlling the valve timing to control the intake air. As shown in FIG. 1, in a variable valve engine controlling the amount, basic ignition timing setting means for setting a basic ignition timing according to the engine speed and load, and a correction amount for the ignition timing according to the valve timing are set. An ignition timing control device for a variable valve engine, comprising: a correction amount setting means for performing the ignition timing determination; and an ignition timing determination means for determining the ignition timing by correcting the basic ignition timing with a correction amount corresponding to the valve timing. I do.

In the invention according to claim 2, the correction amount setting means includes at least a first correction amount setting means for setting a correction amount of the ignition timing according to the intake valve closing timing (IVC). It is characterized by the following. Further, in the invention according to claim 3, the first correction amount setting means sets the correction amount so that the ignition timing is advanced as the effective compression ratio decreases due to a change in the intake valve closing timing. And

According to a fourth aspect of the present invention, the correction amount setting means includes at least a means for setting a correction amount of the ignition timing according to a parameter related to a valve overlap of the intake valve and the exhaust valve. It is characterized by that. Further, in the invention according to claim 5, the parameter related to the valve overlap is determined based on the intake valve opening timing (IV
O) and at least one of the exhaust valve closing timing (EVC).

In the invention according to claim 6, the correction amount setting means includes at least a second correction amount setting means for setting a correction amount of the ignition timing according to the intake valve opening timing (IVO). It is characterized by the following. Further, the invention according to claim 7 is characterized in that the second correction amount setting means sets the correction amount such that the earlier the intake valve opening timing is, the more the ignition timing is advanced.

In the invention according to claim 8, the correction amount setting means includes at least a third correction amount setting means for setting a correction amount of the ignition timing according to the exhaust valve closing timing (EVC). It is characterized by the following. Further, in the invention according to claim 9, the third correction amount setting means advances the ignition timing as the exhaust valve closing timing moves away from the top dead center,
The correction amount is set.

[0017]

According to the first aspect of the present invention, when performing the non-throttle operation by controlling the intake air amount by controlling the valve timing, the basic ignition set according to the engine speed and the load. By correcting the timing in accordance with the valve timing, it is possible to optimize the ignition timing with respect to changes in the effective compression ratio and the internal EGR rate due to changes in the valve timing, thereby improving fuel efficiency and drivability. .

According to the second aspect of the present invention, the basic ignition timing is corrected in accordance with the intake valve closing timing, so that the ignition timing is optimized for a change in the effective compression ratio determined by the intake valve closing timing. As a matter of fact, it is possible to improve fuel efficiency and drivability.

According to the third aspect of the present invention, as the intake valve closing timing is earlier or later and the effective compression ratio is smaller,
By correcting the ignition timing to the advanced side, even if the effective compression ratio decreases due to the early or late closing of the intake valve accompanying non-throttle operation, and the combustion speed decreases, the ignition timing is advanced to stabilize combustion. Nature can be secured.

According to the fourth aspect of the present invention, the basic ignition timing is corrected according to the parameter related to the valve overlap, so that the ignition timing is optimized with respect to the change of the internal EGR rate, and the fuel consumption is improved. And drivability can be improved.

According to the fifth aspect of the present invention, the parameter related to the valve overlap is at least one of the intake valve opening timing and the exhaust valve closing timing, so that the parameter can be accurately determined according to the direct parameter of the valve overlap control. Can be corrected.

According to the sixth aspect of the present invention, the basic ignition timing is corrected in accordance with the intake valve opening timing, so that the ignition timing is optimized with respect to a change in the internal EGR rate accompanying a change in the intake valve opening timing. As a matter of fact, it is possible to improve fuel efficiency and drivability.

According to the seventh aspect of the invention, as the intake valve opening timing is advanced, the blowback of the residual gas increases, the internal EGR rate increases, and the combustion speed decreases. The earlier the ignition timing, the more the ignition timing is corrected to the advanced side, so that the ignition timing is advanced in response to the decrease in combustion speed.
Combustion stability can be ensured.

According to the eighth aspect of the present invention, the basic ignition timing is corrected according to the exhaust valve closing timing, so that the ignition timing is optimized with respect to the change in the internal EGR rate accompanying the change in the exhaust valve closing timing. As a matter of fact, it is possible to improve fuel efficiency and drivability.

According to the ninth aspect, as the exhaust valve closing timing moves away from the top dead center, the scavenging efficiency decreases,
Although the internal EGR rate increases and the combustion speed decreases, the ignition timing is corrected to the advanced side as the exhaust valve closing timing moves away from the top dead center, so that the ignition timing is advanced in response to the decrease in the combustion speed. , Combustion stability can be ensured.

[0026]

Embodiments of the present invention will be described below. FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention.

The combustion chamber 3 defined by the piston 2 of each cylinder of the engine 1 is provided with an electromagnetically driven intake valve 5 and an exhaust valve 6 so as to surround the ignition plug 4. 7 is an intake passage, and 8 is an exhaust passage.

FIG. 3 shows a basic structure of an electromagnetic drive device (variable valve operating device) for the intake valve 5 and the exhaust valve 6. A plate-like mover 22 is attached to a valve shaft 21 of the valve body 20, and the mover 22 is biased to a neutral position by springs 23 and 24. The valve opening electromagnetic coil 25 is disposed below the movable element 22, and the valve closing electromagnetic coil 26 is disposed above the movable element 22.

Therefore, when the valve is opened, the energization of the upper valve closing electromagnetic coil 26 is stopped, and then the lower valve opening electromagnetic coil 25 is energized to attract the movable element 22 to the lower side. As a result, the valve body 20 is lifted to open the valve. vice versa,
When the valve is closed, the energization of the lower valve opening electromagnetic coil 25 is stopped, and then the upper valve closing electromagnetic coil 26 is energized to attract the movable element 22 to the upper side.
Is seated on the seat and the valve is closed.

Returning to FIG. 2, an electronically controlled throttle valve 9 is provided in the intake passage 7 upstream of the intake manifold. The intake passage 7 is also provided with an electromagnetic fuel injection valve 10 for each cylinder at each branch of the intake manifold.

The operation of the intake valve 5, the exhaust valve 6, the electronically controlled throttle valve 9, the fuel injection valve 10, and the spark plug 4 is controlled by a control unit 11, which is synchronized with the engine rotation. And outputs a crank angle signal to thereby detect a crank angle position and an engine speed Ne.
2. An accelerator pedal sensor (including an idle switch that is turned ON when the accelerator is fully closed) 13 for detecting an accelerator opening (accelerator pedal depression amount) APO; an intake air amount (flow rate) Qa upstream of the throttle valve 9 in the intake passage 7 Are input from an air flow meter 14 for detecting the engine temperature, a water temperature sensor 15 for detecting an engine cooling water temperature Tw, and the like.

In the engine 1, for the purpose of improving fuel efficiency by reducing pump loss, the valve timing of the electromagnetically driven intake valve 5 and the exhaust valve 6 is controlled, in particular, by controlling the closing timing IVC of the intake valve 5, the intake air is controlled. The air amount is controlled to perform substantially non-throttle operation. In this case, the electronically controlled throttle valve 9 is provided downstream of the throttle valve 9 in the intake passage 7 (in the intake manifold) for the purpose of obtaining a negative pressure (boost) required for canister purge, crankcase purge, and the like.

Therefore, during the non-throttle operation, the intake valve 5
The valve timing control of the exhaust valve 6 and the opening control of the electronically controlled throttle valve 9 are performed as follows. Accelerator opening A
From the PO and the engine speed Ne, referring to the map,
A target air amount (target cylinder intake air amount) TQ corresponding to the target torque is calculated. However, in the case of idling operation (idle switch ON), based on the difference ΔNe = Ne−Nidle between the engine speed Ne and the target idle speed Nidle, if the difference is on the minus side, the increasing direction, the plus side In the case of, the target air amount TQ is corrected in the decreasing direction. Further, a target boost BT is set based on various engine operating conditions.

Based on the target setting, the target boost T
The throttle opening TVO is calculated from B and the target air amount TQ to achieve the target boost TB, and the electronically controlled throttle valve 9 is controlled.

Then, the intake valve closing timing IVC is calculated from the target air amount TQ so as to realize the target air amount TQ under the target boost TB. Further, based on various engine operating conditions, a target internal EGR rate is set, and an intake valve opening timing IVO and an exhaust valve closing timing EVC are set so as to obtain an optimum valve overlap (overlap position and overlap amount). I do. The exhaust valve opening timing EVO is set in consideration of thermal efficiency and the like.

The electromagnetically driven intake valve 5 and exhaust valve 6 are controlled based on these valve timing settings. FIG. 4 shows an example of the valve timing, and the solid line in the figure indicates the base (at the time of throttle operation) valve timing. The dotted line in the figure is an example of the valve timing during non-throttle operation.

The fuel injection amount and injection timing of the fuel injection valve 10 are controlled based on engine operating conditions. The fuel injection amount is basically based on the intake air amount Qa detected by the air flow meter 14. , So as to achieve a desired air-fuel ratio. The injection end timing is determined by the intake valve opening timing I.
The fuel injection amount is fixed at a predetermined timing before VO, and the injection start timing is controlled so as to obtain the set fuel injection amount.

The control of the ignition timing of the ignition plug 4 will be described with reference to FIG. FIG. 5 is a flowchart of the ignition timing control during the non-throttle operation. In step 1 (referred to as S1 in the figure, the same applies hereinafter), the engine speed Ne is
The target air amount TQ representing the load (torque) is read and
From these, the basic ignition timing MADV at the base valve timing is set with reference to the map of FIG.
This part corresponds to basic ignition timing setting means.

This map determines the optimal ignition timing at the base (at the time of throttle operation) valve timing shown in FIG. 4. The map is advanced as the engine speed Ne increases, and the target air amount TQ increases. As the combustion becomes faster, the ignition timing is set to be retarded.

In step 2, the intake valve closing timing IVC is read, and a correction amount HOS1 = f1 (IVC) for the ignition timing advanced is set with reference to the table of FIG. This part corresponds to first correction amount setting means.

This table defines the correction amount HOS1 to the advance angle side according to the amount of deviation from the valve timing (base IVC) of the base (during throttle operation).
As the intake valve closing timing IVC becomes earlier or later, in other words, as the amount of deviation from the base IVC becomes larger, the effective compression ratio becomes smaller, and the combustion speed decreases. The correction amount HOS1 is determined so as to make correction.

However, the intake valve closing timing IVC is set at the bottom dead center BDC
In the vicinity, the effective compression ratio slightly increases compared to the base IVC, so that the correction amount HOS1 is set to a minus side (a retard side).

In step 3, the intake valve opening timing IVO, which is a parameter for determining the valve overlap, is read. Then, referring to the table of FIG. 8, the ignition timing advance correction amount HOS2 = f2 (IVO) ) Is set. This part corresponds to a second correction amount setting means (also means for setting a correction amount of the ignition timing according to a parameter related to the valve overlap).

This table defines the correction amount HOS2 to the advance angle side in accordance with the deviation amount from the valve timing (base IVO) of the base (during throttle operation).
The earlier the intake valve opening timing IVO, in other words, the greater the deviation from the base IVO, the greater the return of residual gas and the greater the internal EGR rate, thus improving exhaust emissions (particularly NOx emissions). Although it is possible, the combustion speed is reduced and the combustion stability is deteriorated. Accordingly, the correction amount HOS2 is determined so that the ignition timing is corrected to the advanced side in accordance with the combustion speed to secure the combustion stability. .

In step 4, the exhaust valve closing timing EV, which is another parameter for determining the valve overlap,
C is read, and a correction amount HOS3 = f3 (EVC) for the advance of the ignition timing is set with reference to the table of FIG. This part corresponds to third correction amount setting means (also means for setting the correction amount of the ignition timing according to the parameter related to the valve overlap).

This table defines the correction amount HOS3 to the advance angle side in accordance with the deviation amount from the valve timing (base EVC) of the base (during throttle operation).
As the exhaust valve closing timing EVC moves away from the top dead center TDC, the scavenging efficiency decreases and the internal EGR rate increases. Therefore, the exhaust emission (particularly, the amount of NOx emission) can be improved, but the combustion speed decreases and the combustion speed decreases. Since the stability deteriorates, the ignition timing is corrected to the advanced side in accordance with this,
The correction amount HOS3 is determined so as to ensure combustion stability.

However, the exhaust valve closing timing EVC is equal to the top dead center TDC
In the vicinity, the internal EGR rate is slightly lower than the base EVC, so that the correction amount HOS3 is set to the minus side (the retard side).

In step 5, the final ignition timing ADV is calculated by the following equation. ADV = MADV + HOS1 + HOS2 + HOS3 That is, the basic ignition timing MADV is changed to the intake valve closing timing IV.
A correction amount HOS1 to the advance side according to C, the intake valve opening timing I
The final ignition timing ADV is calculated by adding the advance correction amount HOS2 corresponding to VO and the advance correction amount HOS3 corresponding to the exhaust valve closing timing EVC, and based on this, Perform ignition control. This part corresponds to ignition timing determination means.

As described above, when the non-throttle operation is performed by controlling the intake air amount by controlling the intake valve closing timing IVC, the engine speed Ne and the target air amount TQ
The basic ignition timing MADV at the base valve timing (during throttle operation) set according to the intake valve closing timing IVC is corrected according to the intake valve closing timing IVC.
It is possible to improve the fuel efficiency and drivability by optimizing the ignition timing ADV with respect to the change in the effective compression ratio determined by VC.

In particular, as the effective compression ratio decreases as the intake valve closing timing IVC becomes earlier or later and the effective compression ratio becomes smaller, the ignition timing ADV is corrected to the advanced side so that the change in the intake valve closing timing IVC accompanying the non-throttle operation is more effective. Even if the compression ratio decreases and the combustion speed decreases, the ignition timing ADV is advanced,
Can be optimized.

In addition to the basic ignition timing ADV, in addition to the intake valve closing timing IVC, the intake valve opening timing IVO and the exhaust valve opening timing EVC which are parameters related to the valve overlap.
, The ignition timing ADV is optimized with respect to the change in the valve overlap (internal EGR rate), and the fuel efficiency and drivability can be further improved.

In particular, in the case where the internal EGR rate is increased by improving the intake valve opening timing IVO (to increase the returning amount of residual gas) to improve exhaust emission (NOx emission), the intake valve opening timing IVO is improved. As the ignition timing becomes earlier, the ignition timing ADV is corrected to the advanced side, so that the ignition timing ADV is advanced to secure the combustion stability and the operation with MBT against the decrease in the combustion speed due to the increase of the internal EGR rate. As a result, it is possible to achieve both improvement of exhaust emission and securing of combustion stability and fuel efficiency.

The exhaust valve closing timing EVC is set at the top dead center TDC.
The exhaust valve closing timing EVC is separated from the top dead center TDC when the internal EGR rate is increased to improve exhaust emissions (NOx emissions) by increasing the internal EGR rate by increasing the distance from the exhaust valve (reducing the scavenging efficiency and increasing the overlap). The ignition timing ADV
Is advanced to the advanced side, the ignition timing ADV can be advanced to secure the combustion stability and the operation with MBT against the decrease in the combustion speed due to the increase of the internal EGR rate, and the exhaust emission can be improved. And ensuring combustion stability and fuel efficiency.

The correction amount H according to the intake valve opening timing IVO
OS2 and the correction amount HOS3 according to the exhaust valve closing timing EVC
Are both used to correct for changes in the internal EGR rate, so that a single correction amount equivalent to HOS2 + HOS3 may be set from a map using the intake valve opening timing IVO and the exhaust valve closing timing EVC as parameters. Good.

In the case of controlling the internal EGR rate by changing the overlap position while keeping the amount of overlap substantially constant with respect to the valve overlap, the intake valve opening timing IVO and the exhaust valve closing timing EVC are set as follows. The ignition timing may be corrected using the correction amount according to either one.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of a variable valve engine showing one embodiment of the present invention.

FIG. 3 is a basic structural diagram of an electromagnetic drive device of the intake and exhaust valves.

FIG. 4 is a diagram showing an example of valve timing.

FIG. 5 is a flowchart of ignition timing control during non-throttle operation.

FIG. 6 is a diagram showing a map for setting a basic ignition timing.

FIG. 7 is a view showing a table of a correction amount according to an intake valve closing timing IVC;

FIG. 8 is a view showing a table of a correction amount according to an intake valve opening timing IVO;

FIG. 9 is a view showing a table of a correction amount according to the exhaust valve closing timing EVC.

[Explanation of symbols]

 Reference Signs List 1 engine 4 spark plug 5 electromagnetically driven intake valve 6 electromagnetically driven exhaust valve 9 fuel injection valve 10 electrically controlled throttle valve 11 control unit 12 crank angle sensor 13 accelerator pedal sensor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 25/07 510 F02M 25/07 550R 550 F02P 5/15 B F term (reference) 3G022 BA01 DA01 EA01 FA06 GA00 GA01 GA05 GA06 GA08 GA09 3G062 BA08 BA09 EA12 FA10 GA26 3G084 BA05 BA09 BA13 BA15 BA17 BA23 DA02 DA03 DA10 EB08 EB13 FA07 FA10 FA20 FA38 3G092 AA01 AA11 BA01 BA07 BA09 DA01 DA02 DA07 DC01 DG09 EA03 EA04 HA03 HA01 FA10 FAX FA03

Claims (9)

[Claims] 1. A variable valve engine having a variable valve device capable of arbitrarily controlling valve timings of an intake valve and an exhaust valve, and controlling an intake air amount by controlling the valve timing. Basic ignition timing setting means for setting a basic ignition timing in accordance with the following; correction amount setting means for setting a correction amount of the ignition timing in accordance with the valve timing; and correcting the basic ignition timing with a correction amount in accordance with the valve timing. And an ignition timing determining means for determining an ignition timing. 2. The apparatus according to claim 1, wherein said correction amount setting means includes at least a first correction amount setting means for setting a correction amount of an ignition timing according to an intake valve closing timing. Ignition timing control device for variable valve engine. 3. The first correction amount setting means sets the correction amount so that the ignition timing is advanced as the effective compression ratio becomes smaller due to a change in the intake valve closing timing. An ignition timing control device for a variable valve engine according to claim 1. 4. The correction amount setting means includes at least a means for setting a correction amount of an ignition timing according to a parameter related to a valve overlap of an intake valve and an exhaust valve. The ignition timing control device for a variable valve engine according to any one of claims 1 to 3. 5. The ignition timing control device for a variable valve engine according to claim 4, wherein the parameter related to the valve overlap is at least one of an intake valve opening timing and an exhaust valve closing timing. 6. The apparatus according to claim 1, wherein said correction amount setting means includes at least a second correction amount setting means for setting a correction amount of an ignition timing according to an intake valve opening timing. The ignition timing control device for a variable valve engine according to claim 3. 7. The variable valve engine according to claim 6, wherein said second correction amount setting means sets the correction amount so that the ignition timing is advanced as the intake valve opening timing is advanced. Ignition timing control device. 8. The apparatus according to claim 1, wherein said correction amount setting means includes at least a third correction amount setting means for setting a correction amount of the ignition timing according to the exhaust valve closing timing. The ignition timing control device for a variable valve engine according to any one of claims 3, 6, and 7. 9. The correction amount setting means according to claim 8, wherein said third correction amount setting means sets the correction amount so that the ignition timing is advanced as the exhaust valve closing timing moves away from the top dead center. An ignition timing control device for a variable valve engine.