JPH11182284A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform good torque control in input time and non-input time of external load by adequately set load torque compensation part for external load driving according to a required torque in a torque demand control method. SOLUTION: In an operation of an internal combustion engine, a target torque calculating means 101 calculates a target torque of an engine. At this time, load compensation torque for external load driving, when a required torque is large, is corrected to decrease, and the target torque is set according to the corrected load compensation torque. Based on the target torque, demanded basic fuel amount at standard air-fuel ratio (for example, theoretical air-fuel ratio) is calculated 102, and the fuel amount is corrected 103 using fuel consumption efficiency. On the other hand, a target air-fuel ratio calculating means 104 calculates a target air-fuel ratio, and the corrected fuel amount is multiplied by the target air-fuel ratio to calculate 105 a target intake air amount. A target throttle opening matching with the target intake air amount is calculated 106, and an electric throttle valve 4 is driven according to this target throttle opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine which performs torque control by setting a target torque of the engine, and more particularly to a torque control when an external load such as an air conditioner is driven.

[0002]

2. Description of the Related Art In recent years, in a vehicle internal combustion engine, a technique (torque demand control) for setting a target torque of the engine and performing torque control so as to obtain the target torque has been developed. Engines such as gasoline engines that control the amount of intake air have an electronic throttle valve control device that electronically controls the opening of a throttle valve interposed in the intake system of the engine, and controls the opening of the throttle valve according to the target torque. In general, a method of controlling the amount of air while controlling the amount of fuel injection is also common.

On the other hand, when an external load such as an air conditioner is driven, the torque required for the driving is given as a load torque compensation separately from the running torque. The load torque compensation is a torque correction value required at the time of idling. Is set as

[0004]

However, in the conventional torque demand control, the load torque compensation is set as a necessary torque correction value at the time of idling, and the load torque compensation is uniformly incorporated into the target torque other than at the time of idling. Is set to perform the torque control, so that the following problems occur.

That is, at the time of idling, the influence of torque change due to the input of an external load such as an air conditioner or a radiator fan is large, and torque correction is very important from the viewpoint of engine stall prevention. Although it is necessary to set a larger value, in a high load region, the influence of external load application is small, and there is no fear of engine stall. Therefore, the importance of torque correction is not as high as at the time of idling.

[0006] On the other hand, in order to secure the necessary load torque compensation during idling even in a high load region, the amount of torque that can be operated by the accelerator operation of the driver (the running torque in the case of a vehicle internal combustion engine) is limited accordingly. The maximum output when no load is applied is reduced (see FIG. 8). In addition,
In the case where the operable torque is set to be as large as possible considering the limitation by the load torque compensation, the target torque when the load torque compensation is added to the running torque at the intermediate opening of the accelerator when the external load is applied. , The throttle valve opening corresponding to the full throttle is fully opened, the torque cannot be further increased, and a favorable accelerator operation cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem.
It is an object of the present invention to provide a control device for an internal combustion engine that can perform good torque control both when an external load is applied and when an external load is not applied by appropriately setting a load torque compensation amount for driving an external load according to a required torque. Aim.

[0008]

According to a first aspect of the present invention, there is provided a control apparatus for an internal combustion engine for calculating a target torque of an engine and controlling the torque of the engine so as to obtain the target torque. When the required torque is large, the load compensation torque for driving is set by performing correction to decrease the torque, and the target torque is set according to the set load compensation torque.

According to the first aspect of the invention, when the required torque is large, the influence of the torque change due to the application of the external load is reduced, so that even if the load compensation torque for driving the external load is reduced and set, the engine stall can be achieved. On the other hand, the amount of torque operation by the accelerator operation can be increased by an amount corresponding to the reduction of the load compensation torque, and the running performance of the vehicle internal combustion engine can be improved.

According to a second aspect of the present invention, there is provided a control apparatus for an internal combustion engine for calculating a target torque of an engine and controlling the torque of the engine so as to obtain the target torque, as shown in FIG. Load compensation torque setting means for setting the load compensation torque for driving by performing a correction that decreases when the required torque is large, and target torque setting means for setting a target torque according to the set load compensation torque. And is characterized by comprising.

According to the second aspect of the present invention, the load compensation torque setting means sets the load compensation torque for driving the external load to a reduced value when the required torque is large, and the target torque setting means sets the load compensation torque. A target torque is set according to the load compensation torque, and the engine torque is controlled so as to reach the target torque.

In this way, when the required torque is large, the influence of the torque change due to the application of the external load is reduced, so that the engine stall can be prevented even if the load compensation torque for driving the external load is reduced and set. On the other hand, the amount of torque operation by the accelerator operation can be increased by an amount corresponding to the reduction of the load compensation torque, and the running performance of the vehicle internal combustion engine can be improved.

According to a third aspect of the present invention, a constant load compensation torque is set in a low load region below a predetermined value, and the load compensation torque set for the low load region is set in a region other than the low load region. The larger the required amount of torque is, the larger the correction amount is set to be reduced. According to the third aspect of the present invention, in a low load region where the influence of a torque change due to the input of an external load is large, a maximum and constant load compensation torque is applied to alleviate torque shock while preventing engine stall. In this case, since the influence of the torque change due to the input of the external load becomes smaller as the required torque amount becomes larger, the amount of torque operation by the accelerator operation can be increased by setting the load compensation torque to be largely reduced and corrected. .

Further, the invention according to claim 4 is characterized in that the low load region below the predetermined level is an idle region. According to the fourth aspect of the invention, since the torque change due to the input of the external load is large in the idle region, the maximum and constant load compensation torque is given in this region.

Further, the invention according to claim 5 is characterized in that the reduction correction amount of the load compensation torque is obtained by searching from a table set according to the required torque. According to the fifth aspect of the present invention, the optimal load compensation torque is set in accordance with the required torque by setting the amount of reduction in the load compensation torque in the table in a very fine manner in accordance with the required torque. Can be.

Further, the invention according to claim 6 is characterized in that the required torque parameter is a currently set target torque value. According to the sixth aspect of the invention, by setting the required torque parameter to the currently set target torque value, it is possible to easily correct the load compensation torque in the engine that performs the torque demand targeted by the present invention. Can be incorporated into logic.

When a plurality of external loads, such as an air conditioner and a radiator fan, are provided, the ratio of each load compensation torque to the total output torque of the engine, including the load compensation torque for all the input external loads, is made to correspond exactly. To set the correction coefficient. The invention according to claim 7 is characterized in that the required torque parameter is a basic target torque value set by removing the load compensation torque from the target torque value.

According to the seventh aspect of the present invention, the basic target torque value is a torque operation amount by an accelerator operation by a driver, and corresponds to a running minute torque in an internal combustion engine for a vehicle, and a parameter of a required torque is set in the vehicle. By using the basic target torque value, the correction of the load compensation torque can be easily incorporated into the logic in the engine that performs the torque demand targeted by the present invention.

Further, the invention according to claim 8 is characterized in that the required torque parameter is an accelerator opening. According to the invention according to claim 8, the accelerator opening is a torque parameter capable of detecting the driver's intention at high speed and with high accuracy. By setting the required torque parameter to the accelerator opening, the driver's accelerator operation can be performed under a high load. The driver's intention can be directly reflected in ensuring a sufficient operable torque range.

According to a ninth aspect of the present invention, in the internal combustion engine using either the homogeneous combustion or the stratified combustion, the required torque parameter is an intake pressure. . According to the ninth aspect of the invention, by setting the required torque parameter to the intake pressure, it is possible to realize a characteristic very close to the load compensation torque characteristic of the engine that does not perform the torque demand.
It can also respond to environmental changes. Note that an engine that switches between homogeneous combustion and stratified combustion is not preferable because the torque changes even if the intake pressure is the same according to each combustion method.

According to a tenth aspect of the present invention, in the internal combustion engine using either the homogeneous combustion or the stratified combustion, the required torque parameter is an intake air amount. I do. According to the invention according to claim 10, by setting the parameter of the required torque to the intake air amount, in an engine that detects the normal intake air amount and controls the fuel injection amount, high accuracy can be achieved without adding a sensor. The torque parameter can be detected, and accurate torque information can be detected even when the environment changes (such as at high altitude). Note that an engine that switches between homogeneous combustion and stratified combustion is not preferable because the torque changes even if the intake air amount is the same according to each combustion method.

[0022]

Embodiments of the present invention will be described below. FIG. 2 is a system diagram of a direct injection spark ignition type internal combustion engine showing an embodiment. Air is sucked into the combustion chamber of each cylinder of the internal combustion engine 1 mounted on the vehicle from the air cleaner 2 through the intake passage 3 under the control of the electronically controlled throttle valve 4.

The opening of the electronically controlled throttle valve 4 is controlled by a step motor or the like operated by a signal from the control unit 20. An electromagnetic fuel injection valve (injector) 5 is provided so as to directly inject fuel (gasoline) into the combustion chamber. The fuel injection valve 5 is energized by a solenoid in response to an injection pulse signal output in an intake stroke or a compression stroke from the control unit 20 in synchronization with engine rotation, opens the valve, and injects fuel adjusted to a predetermined pressure. It has become. The injected fuel diffuses into the combustion chamber in the case of the intake stroke injection to form a homogeneous mixture, and in the case of the compression stroke injection, forms a layered mixture intensively around the spark plug 6. Based on an ignition signal from the control unit 20, the ignition plug 6 ignites the fuel and performs combustion (homogeneous combustion or stratified combustion). The combustion method is a combination of air-fuel ratio control and homogeneous stoichiometric combustion.
It is divided into homogeneous lean combustion (air-fuel ratio of 20 to 30) and stratified lean combustion (air-fuel ratio of about 40).

The exhaust gas from the engine 1 is exhausted from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7. The control unit 20 includes a CPU, a ROM, an R
A microcomputer including an AM, an A / D converter, an input / output interface, and the like is provided, and signals are input from various sensors.

The various sensors include a crank angle sensor 2 for detecting rotation of the crankshaft or camshaft of the engine 1.
1 and 22 are provided. These crank angle sensors 21 and 22 have a crank angle of 720 when the number of cylinders is n.
The reference pulse signal RE at a predetermined crank angle position (a predetermined crank angle position before the compression top dead center of each cylinder) at every ° / n.
F and outputs the unit pulse signal PO every 1-2 °.
S is output, and the engine speed Ne can be calculated from the period of the reference pulse signal REF and the like.

In addition, an air flow meter 23 for detecting an intake air flow rate Qa upstream of the throttle valve 4 in the intake passage 3,
Accelerator sensor 24 for detecting accelerator opening (accelerator pedal depression amount) ACC, opening TV of throttle valve 4
A throttle sensor 25 for detecting O (including an idle switch that is turned on when the throttle valve 4 is fully closed), a water temperature sensor 26 for detecting the cooling water temperature Tw of the engine 1, and a rich / lean exhaust air-fuel ratio in the exhaust passage 7. An O ₂ sensor 27 that outputs a signal corresponding to the vehicle speed, a vehicle speed sensor 28 that detects a vehicle speed VSP, and the like are provided. In addition, an air conditioner switch 29 that is turned on and off in accordance with driving and non-driving of the air conditioner as an external load is provided.

Here, the control unit 20
Performs predetermined arithmetic processing by a built-in microcomputer while inputting signals from the above-mentioned various sensors, and performs a throttle opening degree by the electronically controlled throttle valve 4, a fuel injection amount by the fuel injection valve 5, a fuel injection timing. And the ignition timing of the ignition plug 6 is controlled. Next, an outline of torque demand control by the above-mentioned system will be described with reference to FIG.

A target torque of the engine is calculated (101), and a reference air-fuel ratio (for example, a stoichiometric air-fuel ratio) is calculated based on the target torque.
The required basic fuel amount in is calculated (102). on the other hand,
A target air-fuel ratio is calculated (103), a fuel amount is corrected based on fuel efficiency according to the target air-fuel ratio (104), and a target intake air amount is calculated by multiplying the corrected fuel amount by the target air-fuel ratio. (105) The target throttle opening corresponding to the target intake air amount is calculated (106), and drive control is performed so as to obtain the target throttle opening (107), and the electronically controlled throttle valve is driven.

The present invention is characterized in calculating the load compensation torque used in calculating the target torque. Hereinafter, the calculation of the load compensation torque according to the present invention will be described with reference to the drawings. FIG. 4 is a flowchart of a load compensation torque calculation routine according to the first embodiment. This routine is executed at regular intervals, for example, every 10 ms.

In step 1, the air conditioner switch ACS
It is determined whether W is ON or OFF. If it is determined in step 1 that the air conditioner switch ACSW is ON, the process proceeds to step 2 to read the load compensation torque dTac required for driving the air conditioner during idling. If it is determined in step 1 that the air conditioner switch ACSW is OFF, step 3
Then, the load compensation torque dTac is reset to zero. As a result, when the air conditioner is turned off, a final load compensation torque dTac 'described later also becomes zero.

The process proceeds from step 2 or step 3 to step 4 where the idle switch O
It is determined whether or not the engine is in an idle state based on N and OFF. If it is determined in step 4 that the vehicle is in the idle state, the routine proceeds to step 5, sets the correction coefficient Gadj of the load compensation torque dTac to 1, and then proceeds to step 8. The correction coefficient Gadj is, as described later, a load compensation torque dTa.
This is a value that is multiplied by c, and therefore, the load compensation torque dTac is not corrected during idling.

If it is determined in step 4 that the vehicle is in the non-idle state, the routine proceeds to step 6, where the required torque parameter is read. As a parameter of the required torque, for example, a running target torque tTe0 determined as described later.
Read. The traveling target torque Te0 is a torque required only for traveling excluding a torque required for driving an external load such as an air conditioner.

Then, the process proceeds to a step 7, wherein a correction coefficient Gadj of the load compensation torque dTac is calculated based on the required torque parameter read in the step 3. For example, when the travel target torque tTe0 is read as the required torque, the load compensation torque dTac is greatly reduced and corrected as the travel target torque tTe0 increases, so that the following equation (1) is used. A correction coefficient Gadj is calculated.

Gadj = K / tTe0 (1) where K is a gain. Instead of the calculation using the above equation, a correction coefficient Gadj for the running target torque tTe0 as shown in FIG.
May be set and a search is performed from the table, so that the correction coefficient Gadj can be determined very finely. In step 8, the correction coefficient G is added to the load compensation torque dTac corresponding to the idling time as in the following equation (2).
The final load compensation torque dTac 'is calculated by multiplying adj by adj.

DTac '= Gadj × dTac (2) The load compensation torque dTac' calculated as described above.
Is used to set the target torque tTe of the engine. A routine for setting the target torque tTe will be described with reference to the flowchart of FIG. This routine is executed at regular intervals, for example, every 10 ms.

In step 11, the running target torque t
Calculate Te0. Specifically, it may be obtained by searching a preset table based on the accelerator opening and the engine speed (or the vehicle speed). In step 12,
The final target torque target torque tTe is calculated by adding the load compensation torque dTac ′ (0 when the air conditioner is not driven) to the travel target torque tTe0 as in the following equation.

In step 13, the target torque tTe is set in a memory. Using the target torque tTe of the engine set as described above, the torque control is executed as shown in FIG. By doing so, at the time of idling, the load compensation torque dTac required at the time of idling
By setting, it is possible to eliminate torque shock when an external load such as an air conditioner is applied, to prevent engine stall, and to set the load compensation torque dTac ', which decreases greatly as the required torque increases when the engine is not idling. As shown in FIG. 8, the amount of torque operation by the accelerator operation is increased, and the running performance is improved. That is, the torque can be continuously increased from the fully closed state to the fully opened state of the accelerator when the external load is applied, and the maximum output when the external load is not applied can be sufficiently large.

In the above embodiment, the load compensation torque is reduced and corrected in accordance with the required torque in the non-idle state. However, even in the non-idle state, the external load is applied in the low load range close to the idle state. In order to completely eliminate the influence of torque shock due to the above, the load compensation torque value may be fixed to the same value as at the time of idling. FIG. 7 shows a flowchart of a load compensation torque setting routine according to the second embodiment having the above configuration.

The difference from the first embodiment shown in FIG. 4 is that when it is determined in step 4 that the vehicle is not idling, the load compensation is performed in step 21 according to the required torque parameter read in step 6. It is determined whether the torque reduction correction condition is satisfied. Specifically, the required torque parameter, for example, the running target torque tTe0 is set to a predetermined value tT.
In the low load state equal to or less than e1, it is determined that the condition for decreasing the load compensation torque is not satisfied as in the case of idling, and the routine proceeds to step 5, where the correction coefficient Gadj is set to 1, and the load compensation is performed only when the predetermined value tTe1 is exceeded. It is determined that the torque reduction correction condition is satisfied, and the routine proceeds to step 7, where the correction coefficient Gadj of the load compensation torque is calculated. When the correction coefficient Gadj of the load compensation torque is calculated by an arithmetic expression, the above expression (1) may be used, and the correction coefficient Gadj may be obtained by searching from a table.

In the above embodiment, the correction coefficient G
The travel target torque tTe0 is used as a parameter of the required torque used when obtaining adj, and in this case, in the engine that performs the torque demand targeted by the present invention,
The correction of the load compensation torque can be easily incorporated into the logic. Alternatively, the currently set target torque tTe may be used as a parameter of the required torque. In this case, immediately after the external load is applied, the target torque that does not include the load compensation torque before the application is used, but there is no problem because it is instantaneous, and when there are multiple external loads such as an air conditioner and a radiator fan, The correction coefficient can be set so as to accurately correspond to the ratio of each load compensation torque to the total output torque of the engine including the load compensation torque for all the external loads.

Also, the accelerator opening may be used as a parameter of the required torque, and the driver's intention can be detected at high speed and with high accuracy. Intention can be directly reflected. In the internal combustion engine that switches between homogeneous combustion and stratified combustion as described in the above-described embodiment, the required torque parameters such as the running target torque tTe0, the target torque tTe, and the accelerator opening are set as described above. Can be used as a parameter that accurately represents the magnitude of the required torque regardless of the switching.

On the other hand, in an internal combustion engine using either the homogeneous combustion or the stratified combustion, an intake negative pressure (boost pressure) or an intake air amount can be used as a parameter of the required torque. Note that an engine that switches between homogeneous combustion and stratified combustion is not preferable because the torque changes even if the intake negative pressure or the intake air amount is the same according to each combustion method.

When the intake negative pressure is used as the required torque parameter, a pressure sensor is installed in the intake collector to detect the intake negative pressure PB, read the intake negative pressure PB as a required torque parameter, and correct the load compensation torque. Coefficient Ga
dj is calculated by the following equation (3). Alternatively, it can be obtained by a search from a table or the like. Gadj = | PB | × K (K is a correction gain) (3) In an engine that does not perform the torque demand, the load compensation torque is generally given by increasing the throttle opening constantly.
In this case, the load compensation torque is automatically reduced due to the decrease in the intake negative pressure according to the increase in the load. Therefore, the load compensation torque is reduced according to the intake negative pressure in the engine that performs the torque demand as described above. In the correction, a characteristic very close to the load compensation torque characteristic of the engine that does not perform the torque demand can be realized. In addition, it is possible to cope with environmental changes by using a pressure sensor.

In the case where the intake air amount is used as a parameter of the required torque, an engine provided with an intake air amount sensor such as a normal hot-wire type air flow meter for controlling the fuel injection amount while detecting the intake air amount is used. Accurate torque parameters can be detected without addition, and accurate torque information can be detected even if the environment changes (such as at high altitudes) due to the detection of the mass intake air amount.

[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 showing an embodiment of the present invention.

FIG. 3 is a block diagram showing an outline of torque demand control in the embodiment.

FIG. 4 is a flowchart showing a routine for setting a load compensation torque in the embodiment.

FIG. 5 is also a travel target torque / load compensation torque correction coefficient conversion table.

FIG. 6 is a flowchart showing a routine for similarly setting a target torque.

FIG. 7 is a flowchart showing a routine for setting a load compensation torque in the second embodiment.

FIG. 8 is a diagram showing a ratio between a driver operation torque and a load compensation torque in comparison with a conventional example and the present invention.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 4 electrically controlled throttle valve 5 fuel injection valve 6 spark plug 20 control unit 29 air conditioner switch

Claims (10)

[Claims] In a control apparatus for an internal combustion engine, which calculates a target torque of an engine and controls the torque of the engine so as to obtain the target torque, a load compensation torque for driving an external load is increased when a required torque is large. A control device for an internal combustion engine, wherein a target torque is set according to the set load compensation torque. 2. A control device for an internal combustion engine which calculates a target torque of an engine and controls the engine torque so as to obtain the target torque. Is a load compensating torque setting means for setting by performing a correction to decrease, and a target torque setting means for setting a target torque in accordance with the set load compensating torque. Control device. 3. A constant load compensation torque is set in a low load region equal to or less than a predetermined value, and in a region other than the low load region, the load compensation torque set for the low load region is set to a large required torque amount. The control device for an internal combustion engine according to claim 1 or 2, wherein the control device sets the correction value so that the correction value is reduced as much as possible. 4. The control device for an internal combustion engine according to claim 3, wherein the low load region below the predetermined value is an idle region. 5. The method according to claim 1, wherein the amount of decrease in the load compensation torque is determined by searching a table set according to the required torque. Internal combustion engine control device. 6. The control apparatus for an internal combustion engine according to claim 1, wherein the required torque parameter is a currently set target torque value. 7. The method according to claim 1, wherein the required torque parameter is a basic target torque value set by removing the load compensation torque from the target torque value. 3. The control device for an internal combustion engine according to claim 1. 8. The system according to claim 1, wherein the required torque parameter is an accelerator opening.
The control device for an internal combustion engine according to any one of the above. 9. An internal combustion engine using one of a homogeneous combustion mode and a stratified combustion mode, wherein the required torque parameter is an intake pressure. A control device for an internal combustion engine according to any one of the preceding claims. 10. The internal combustion engine using one of a homogeneous combustion combustion and a stratified combustion combustion, wherein the required torque parameter is an intake air amount. The control device for an internal combustion engine according to any one of the above.