JP3812111B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine that performs torque control by setting a target torque of the engine, and more particularly to torque control when driving an external load such as an air conditioner.
[0002]
[Prior art]
In recent years, in a vehicle internal combustion engine, development of 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 advanced. An engine that controls the amount of intake air, such as a gasoline engine, is equipped with an electronic throttle valve control device that electronically controls the opening of a throttle valve interposed in the intake system of the engine, and the throttle valve opening is controlled according to the target torque. Thus, a method of controlling the amount of air and the amount of fuel injection is common.
[0003]
On the other hand, when driving an external load such as an air conditioner, the torque required for the driving is provided as a load torque compensation component separately from the travel torque component, but this load torque compensation component is set as a torque correction value required during idling. ing.
[0004]
[Problems to be solved by the invention]
However, in the conventional torque demand control, the load torque compensation amount is set as a torque correction value necessary at the time of idling, and the torque control is performed by setting the target torque by uniformly incorporating the load torque compensation amount even at the time of idling. Therefore, there were the following problems.
[0005]
In other words, during idling, the effect of torque changes due to external loads such as air conditioners and radiator fans is large, and torque correction is very important from the standpoint of engine stall prevention. Therefore, the load torque compensation amount must be increased to perform sufficient torque correction. While it is necessary to set the torque correction, the influence of external load is small in the high load region and there is no concern about engine stall. Therefore, the importance of torque correction is not as high as that during idling.
[0006]
On the other hand, in order to secure the load torque compensation required during idling even in the high load range, the amount of torque that can be operated by the driver's accelerator operation (running torque for the vehicle internal combustion engine) is limited accordingly, and no external load is applied. The maximum output at the time is reduced (see FIG. 8). Note that when the operable torque is set to the maximum without considering the limitation due to the load torque compensation, the load torque compensation is added to the running torque at the accelerator middle opening when the external load is applied. The throttle valve opening corresponding to the target torque is fully opened, and the torque cannot be increased any further, and a favorable accelerator operation cannot be performed.
[0007]
The present invention has been made paying attention to such a conventional problem, and in the torque demand control system, by appropriately setting the load torque compensation amount for driving the external load according to the required torque, 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 the engine is turned off and when it is not applied.
[0008]
[Means for Solving the Problems]
For this reason, the invention according to claim 1
In a control device for an internal combustion engine that 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 set by performing a correction calculation that decreases when the required torque of the engine according to the amount of operation of the driver is large, and the set load compensation torque is added to the required torque. The target torque is thus set .
[0009]
According to the invention of claim 1,
When the required torque is large, the effect of torque change due to external load input is reduced, so even if the load compensation torque for driving the external load is reduced and set, the engine stall can be prevented, while the load compensation torque is reduced. Thus, the torque operation by the accelerator operation can be increased, and the traveling performance can be improved in the vehicle internal combustion engine.
[0010]
Moreover, as shown in FIG.
In a control device for an internal combustion engine that calculates a target torque of an engine and controls the torque of the engine so as to obtain the target torque.
Load compensation torque setting means for setting a load compensation torque for external load driving by performing a correction calculation that decreases when the required torque of the engine according to the operation amount of the driver is large ;
And a target torque setting means for setting the target torque by adding the set load compensation torque to the required torque .
[0011]
According to the invention of claim 2,
The load compensation torque setting means reduces and sets the load compensation torque for external load driving when the required torque is large, and the target torque setting means sets the target torque according to the set load compensation torque, The engine torque is controlled to achieve the target torque.
[0012]
In this way, when the required torque is large, the influence of torque change due to the input of the external load is reduced. Therefore, even if the load compensation torque for driving the external load is reduced and set, the engine stall can be prevented. As the load compensation torque is reduced, the torque operation by the accelerator operation can be increased, and the vehicle internal combustion engine can improve the running performance.
[0013]
The invention according to claim 3
A constant load compensation torque is set in a low load region below a predetermined value, and in regions other than the low load region, the load compensation torque set for the low load region is greatly reduced as the required amount of torque increases. It is characterized by setting.
According to the invention of claim 3,
In the low load region where the effect of torque change due to external load input is large, the engine torque is prevented while giving a maximum and constant load compensation torque to prevent engine stall. In the larger load region, the required amount of torque is large. Since the influence of the torque change due to the external load input becomes smaller as occasion demands, the amount of torque operation by the accelerator operation can be increased by setting the load compensation torque to be greatly decreased and corrected.
[0014]
The invention according to claim 4
The low load area below the predetermined range is an idle area.
According to the invention of claim 4,
Since the influence of the torque change due to the external load is great in the idle region, the maximum and constant load compensation torque is given in this region.
[0015]
The invention according to claim 5
The load compensation torque reduction correction amount is obtained by searching from a table set according to the required torque.
According to the invention of claim 5,
By setting the amount of load compensation torque decrease correction in the table in accordance with the required torque, the optimum load compensation torque can be set according to the required torque.
[0016]
The invention according to claim 6
The required torque parameter is a currently set target torque value.
According to the invention of claim 6,
By setting the required torque parameter to the currently set target torque value, it is possible to easily incorporate the correction of the load compensation torque into the logic in the engine that performs the torque demand of the present invention.
[0017]
In addition, when there are multiple external loads such as air conditioners and radiator fans, the correction coefficient is made 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 applied Can be set.
The invention according to claim 7
The required torque parameter is a basic target torque value set by excluding the load compensation torque from the target torque value.
[0018]
According to the invention of claim 7,
The basic target torque value is the amount of torque operated by the driver's accelerator operation. In the internal combustion engine for a vehicle, the basic target torque value corresponds to the amount of traveling torque, and the required torque parameter is set as the basic target torque value. In the engine that performs the target torque demand, the correction of the load compensation torque can be easily incorporated into the logic.
[0019]
The invention according to claim 8 is
The required torque parameter is an accelerator opening.
According to the invention of claim 8,
The accelerator opening is a torque parameter that can accurately detect the driver's intention at high speed. By making the required torque parameter the accelerator opening, a sufficient torque range that the driver can operate at high loads is secured. The driver's intention can be directly reflected.
[0020]
The invention according to claim 9 is
In an internal combustion engine that uses either one of homogeneous combustion and stratified combustion, the required torque parameter is intake pressure.
According to the invention of claim 9,
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 an engine that does not perform torque demand, and to cope with environmental changes. 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.
[0021]
The invention according to claim 10 is
In an internal combustion engine that uses either a homogeneous combustion or a stratified combustion method, the required torque parameter is an intake air amount.
According to the invention of claim 10,
By setting the required torque parameter as the intake air amount, it is possible to detect an accurate torque parameter without adding a sensor in an engine that detects the normal intake air amount and performs fuel injection amount control. In addition, accurate torque information can be detected even when the environment changes (such as high altitudes). 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]
DETAILED DESCRIPTION OF THE INVENTION
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 under the control of the electric throttle valve 4 from the air cleaner 2 through the intake passage 3.
[0023]
The opening degree of the electronically controlled throttle valve 4 is controlled by a step motor or the like that is operated by a signal from the control unit 20.
An electromagnetic fuel injection valve (injector) 5 is provided to inject fuel (gasoline) directly into the combustion chamber.
The fuel injection valve 5 is energized to the solenoid by an injection pulse signal output in the intake stroke or the compression stroke in synchronization with the engine rotation from the control unit 20 to open the valve, and injects fuel adjusted to a predetermined pressure. It is like that. In the case of intake stroke injection, the injected fuel diffuses into the combustion chamber to form a homogeneous mixture, and in the case of compression stroke injection, a stratified mixture is intensively formed around the spark plug 6. Based on the ignition signal from the control unit 20, the ignition plug 6 ignites and burns (homogeneous combustion or stratified combustion). The combustion system is classified into homogeneous stoichiometric combustion, homogeneous lean combustion (air-fuel ratio 20 to 30), and stratified lean combustion (air-fuel ratio of about 40) in combination with air-fuel ratio control.
[0024]
Exhaust gas from the engine 1 is discharged from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7.
The control unit 20 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, and signals are input from various sensors.
[0025]
As the various sensors, crank angle sensors 21 and 22 for detecting rotation of the crankshaft or camshaft of the engine 1 are provided. These crank angle sensors 21 and 22 have a reference pulse at a predetermined crank angle position (predetermined crank angle position before compression top dead center of each cylinder) every crank angle 720 ° / n, where n is the number of cylinders. In addition to outputting the signal REF, the unit pulse signal POS is output every 1 to 2 °, and the engine speed Ne can be calculated from the cycle of the reference pulse signal REF.
[0026]
In addition, an air flow meter 23 for detecting the intake air flow rate Qa upstream of the throttle valve 4 in the intake passage 3, an accelerator sensor 24 for detecting an accelerator opening (accelerator pedal depression amount) ACC, and an opening TVO of the throttle valve 4 are detected. The throttle sensor 25 (including an idle switch that is turned on when the throttle valve 4 is fully closed), the water temperature sensor 26 that detects the cooling water temperature Tw of the engine 1, and the exhaust passage 7 according to the rich / lean exhaust air / fuel ratio. An O ₂ sensor 27 that outputs a signal, 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 according to whether the air conditioner is driven or not as an external load is provided.
[0027]
Here, the control unit 20 performs a predetermined calculation process by a built-in microcomputer while inputting signals from the various sensors, so that the throttle opening by the electric throttle valve 4 and the fuel by the fuel injection valve 5 are processed. The injection amount, fuel injection timing, and ignition timing by the spark plug 6 are controlled.
Next, an overview of torque demand control by the system will be described with reference to FIG.
[0028]
A target torque of the engine is calculated (101), and a necessary basic fuel amount at a reference air-fuel ratio (for example, theoretical air-fuel ratio) is calculated based on the target torque (102). On the other hand, the target air-fuel ratio is calculated (103), the fuel amount is corrected based on the fuel efficiency according to the target air-fuel ratio (104), and the target intake air amount is calculated by multiplying the corrected fuel amount by the target air-fuel ratio. Calculate (105), calculate the target throttle opening corresponding to the target intake air amount (106), perform drive control so as to obtain the target throttle opening (107), and drive the electric throttle valve To do.
[0029]
The present invention is characterized in the calculation of the load compensation torque used in calculating the target torque.
Hereinafter, 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.
[0030]
In step 1, it is determined whether the air conditioner switch ACSW is ON or OFF.
When 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.
When it is determined at step 1 that the air conditioner switch ACSW is OFF, the routine proceeds to step 3 where the load compensation torque dTac is reset to zero. Thereby, when the air conditioner is OFF, the final load compensation torque dTac ′ described later is also zero.
[0031]
The process proceeds from step 2 or step 3 to step 4, where it is determined whether or not the engine is in an idle state by turning on or off the idle switch.
When it is determined in step 4 that the engine is in the idle state, the process proceeds to step 5 to set the correction coefficient Gadj of the load compensation torque dTac to 1, and then proceeds to step 8. The correction coefficient Gadj is a value that is multiplied by the load compensation torque dTac, as will be described later. Therefore, the correction of the load compensation torque dTac is not performed during idling.
[0032]
When it is determined in step 4 that the vehicle is in the non-idle state, the process proceeds to step 6 and the parameter of the required torque is read. As the parameter of the required torque, for example, a travel target torque tTe0 obtained as described later is read. The travel target torque Te0 is a torque required only for travel .
[0033]
Next, the routine proceeds to step 7, where the correction coefficient Gadj of the load compensation torque dTac is calculated based on the required torque parameter read in step 3. For example, when the travel target torque tTe0 is read as the required torque, the load compensation torque dTac is greatly decreased and corrected as the travel target torque tTe0 increases, so that the following equation (1) is used. A correction coefficient Gadj is calculated.
[0034]
Gadj = K / tTe0 (1) where K is a gain, or a table of correction coefficient Gadj for travel target torque tTe0 as shown in FIG. The correction coefficient Gadj can be obtained very finely.
In step 8, the final load compensation torque dTac ′ is calculated by multiplying the load compensation torque dTac corresponding to the idling time by the correction coefficient Gadj as shown in the following equation (2).
[0035]
dTac ′ = Gadj × dTac (2)
The engine target torque tTe is set using the load compensation torque dTac ′ calculated as described above.
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.
[0036]
In step 11, the travel target torque tTe0 is calculated. Specifically, it may be obtained by searching from a preset table based on the accelerator opening and the engine rotational speed (or 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 shown in the following equation.
[0037]
In step 13, the target torque tTe is set in the memory.
Using the engine target torque tTe set as described above, torque control is executed as shown in FIG.
In this way, by setting the load compensation torque dTac necessary at the time of idling at the time of idling, it is possible to eliminate torque shock when an external load such as an air conditioner is turned on and to prevent engine stall, and at the time of non-idling, the required torque By setting the load compensation torque dTac ′ so as to increase, the amount of torque operation by the accelerator operation increases as shown in FIG. 8, and the running performance improves. That is, when the external load is applied, the torque can be continuously increased from the accelerator fully closed to the fully open, and the maximum output when the external load is not applied can be secured sufficiently large.
[0038]
In the above-described embodiment, the non-idle load compensation torque is corrected so as to be reduced according to the magnitude of the required torque. In order to completely eliminate the influence of the above, the load compensation torque value may be fixed to the same value as that during idling.
FIG. 7 shows a flowchart of a load compensation torque setting routine in the second embodiment having the above-described configuration.
[0039]
The difference from the first embodiment shown in FIG. 4 is that when the non-idle state is determined in step 4, the load compensation torque is reduced in step 21 in accordance with the parameter of the requested torque read in step 6. It is determined whether the correction condition is satisfied.
Specifically, in a low load state in which the required torque parameter, for example, the travel target torque tTe0 is equal to or less than the predetermined value tTe1, it is determined that the load compensation torque decrease correction condition is not satisfied as in the idling state, and the process proceeds to step 5 The correction coefficient Gadj is set to 1, and only when the predetermined value tTe1 is exceeded, it is determined that the load compensation torque decrease correction condition is satisfied, and the process proceeds to step 7 to calculate the load compensation torque correction coefficient Gadj. When calculating the correction coefficient Gadj of the load compensation torque by an arithmetic expression, the above expression (1) may be used, and it may be obtained by searching from a table.
[0040]
In the above embodiment, the travel target torque tTe0 is used as a parameter of the required torque used when the correction coefficient Gadj is obtained. In this case, in the engine that performs the torque demand targeted by the present invention, the load compensation is performed. Torque correction can be easily incorporated into the logic.
Alternatively, the currently set target torque tTe may be used as a required torque parameter. In this case, the target torque that does not include the load compensation torque before the input immediately after the external load is applied is used, but there is no problem because it is instantaneous, and it is applied when there are multiple external loads such as an air conditioner radiator fan. The correction coefficient can be set in correspondence with the ratio of each load compensation torque to the total output torque of the engine including the load compensation torque for all external loads.
[0041]
In addition, the accelerator opening may be used as a parameter for the required torque, and the driver's intention can be detected accurately at high speed. It can be reflected.
Further, the required torque parameters such as the travel target torque tTe0, the target torque tTe, and the accelerator opening shown above are the same in the internal combustion engine that switches between homogeneous combustion and stratified combustion as shown in the embodiment. It can be used as a parameter that accurately represents the magnitude of the required torque regardless of the switching.
[0042]
On the other hand, in an internal combustion engine that uses either one of homogeneous combustion and stratified combustion, intake negative pressure (boost pressure) or intake air amount can be used as a parameter for the required torque. An engine that switches between homogeneous combustion and stratified combustion is not preferable because the torque changes even if the intake negative pressure and the intake air amount are the same according to each combustion method.
[0043]
When intake negative pressure is used as a required torque parameter, a pressure sensor is installed in the intake collector to detect intake negative pressure PB, read the intake negative pressure PB as a required torque parameter, and a load compensation torque correction coefficient Gadj is calculated. It is calculated by an arithmetic expression such as the following expression (3). Alternatively, it can be obtained by searching from a table or the like.
Gadj = | PB | × K (K is a correction gain) (3)
In an engine that does not perform torque demand, load compensation torque is generally given by increasing the throttle opening by a certain amount. In this case, the load compensation torque is automatically reduced by a decrease in intake negative pressure as the load increases. Therefore, in the engine that performs torque demand as described above, when the load compensation torque is corrected to decrease according to the intake negative pressure, a characteristic very close to the load compensation torque characteristic of the engine that does not perform the torque demand is realized. be able to. In addition, the use of a pressure sensor can cope with environmental changes.
[0044]
In addition, when the intake air amount is used as a parameter for the required torque, a sensor is added in an engine that includes an intake air amount sensor such as a normal hot-wire air flow meter and controls the fuel injection amount while detecting the intake air amount. Therefore, accurate torque parameters can be detected, and accurate torque information can be detected even if the environment changes (e.g., high altitude) by detecting 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 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 of a driver operation torque and a load compensation torque in comparison with a conventional example and the present invention.
[Explanation of symbols]
1 Internal combustion engine 4 Electric throttle valve 5 Fuel injection valve 6 Spark plug
20 Control unit
29 Air conditioner switch

Claims (9)

In a control device for an internal combustion engine that 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 set by performing a correction calculation that decreases when the required torque of the engine according to the amount of operation of the driver is large, and the set load compensation torque is added to the required torque. A control device for an internal combustion engine, characterized in that a target torque is set. In a control device for an internal combustion engine that calculates a target torque of an engine and controls the torque of the engine so as to obtain the target torque.
Load compensation torque setting means for setting a load compensation torque for external load driving by performing a correction calculation that decreases when the required torque of the engine according to the operation amount of the driver is large;
A control device for an internal combustion engine, comprising: target torque setting means for setting a target torque by adding the set load compensation torque to the required torque.   A constant load compensation torque is set in a low load region below a predetermined range, and the load compensation torque set for the low load region in a region other than the low load region is greatly reduced as the required amount of torque increases. The control device for an internal combustion engine according to claim 1 or 2, wherein the control device is set as follows.   The control apparatus for an internal combustion engine according to claim 3, wherein the predetermined low load region is an idle region.   The internal combustion engine control according to any one of claims 1 to 4, wherein a reduction correction amount of the load compensation torque is obtained by searching from a table set in accordance with a required torque. apparatus.   The internal combustion engine according to any one of claims 1 to 5, wherein the required torque parameter is a basic target torque value set by excluding a load compensation torque from a target torque value. Control device.   6. The control device for an internal combustion engine according to claim 1, wherein the required torque parameter is an accelerator opening.   6. An internal combustion engine that uses either one of homogeneous combustion and stratified combustion, wherein the required torque parameter is intake air pressure. The internal combustion engine control device described.   6. An internal combustion engine using either a homogeneous combustion or a stratified combustion method, wherein the required torque parameter is an intake air amount. The control apparatus of the internal combustion engine described in 1.

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