JP3879270B2 - Negative pressure control device for in-vehicle internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a negative pressure control device for an in-vehicle internal combustion engine in which stratified combustion is performed.
[0002]
[Prior art]
In general, in an in-vehicle internal combustion engine such as an automobile engine, an air-fuel mixture is formed by mixing air sucked into a combustion chamber through an intake passage and fuel injected from a fuel injection valve, and the air-fuel mixture is combusted. Driving power is obtained by burning indoors. The intake passage of such an internal combustion engine is provided with a throttle valve for adjusting the amount of air taken into the combustion chamber. By adjusting the amount of air sucked into the combustion chamber by adjusting the opening of the throttle valve, the amount of air-fuel mixture charged into the combustion chamber changes, and the output of the internal combustion engine is adjusted. Become.
[0003]
By the way, in recent years, an internal combustion engine of a type that switches a combustion system in accordance with an engine operating state has been proposed and put into practical use in order to achieve both improvement in fuel efficiency and obtaining sufficient engine output.
[0004]
These types of internal combustion engines perform “homogeneous combustion” in which a homogeneous mixture in which fuel is evenly mixed with air is burned at high rotation and high load where high output is required to obtain sufficient engine output. I have to. In this "homogeneous combustion", the fuel injected and supplied into the combustion chamber in the intake stroke of the internal combustion engine is evenly mixed with the air in the combustion chamber, and the air-fuel mixture formed from the air and fuel is ignited by the spark plug. It is executed by doing.
[0005]
Also, at low rotation and low load, where high output is not required, the fuel concentration around the spark plug is increased to improve ignitability, and the average air-fuel ratio of the air-fuel mixture is made larger than the stoichiometric air-fuel ratio to improve fuel efficiency. Perform “stratified combustion” possible. In this "stratified combustion", the fuel injected and supplied into the combustion chamber in the compression stroke of the internal combustion engine hits a recess in the piston head and is collected around the spark plug, and is a mixture consisting of the collected fuel and air in the combustion chamber. It is executed by being ignited by a spark plug. In such “stratified combustion”, the throttle valve is controlled to open more than in the case of “homogeneous combustion” in order to increase the average air-fuel ratio of the air-fuel mixture, so that the pumping loss is reduced.
[0006]
By switching the combustion method of the internal combustion engine between “homogeneous combustion” and “stratified combustion” according to the engine operating state as described above, fuel efficiency can be improved and sufficient engine output can be obtained. become.
[0007]
By the way, in an in-vehicle internal combustion engine, a brake booster that reduces the brake depressing operation force of an automobile is driven using negative pressure generated in an intake system, or an automobile air conditioner is driven based on engine output. ing. The brake booster accumulates a negative pressure generated in an intake system of an in-vehicle internal combustion engine as a brake negative pressure, and is driven by the brake negative pressure. It is also conceivable to apply such a brake booster to an internal combustion engine in which the stratified combustion is performed. However, in this case, since the opening of the throttle valve during stratified combustion becomes a value on the open side compared to homogeneous combustion, the negative pressure generated in the intake system of the in-vehicle internal combustion engine becomes the value on the atmospheric pressure side, It becomes difficult to secure the brake negative pressure necessary for driving the brake booster. In particular, it is difficult to ensure the above-described brake negative pressure during low-speed operation of the on-board internal combustion engine, such as during idling while the vehicle is stopped or when the vehicle is traveling at a very low speed.
[0008]
Therefore, conventionally, it has been proposed to control the closing of the throttle valve in order to ensure a brake negative pressure for driving the brake booster. As a device for performing such throttle valve closing control, for example, a negative pressure control device described in Japanese Patent Application Laid-Open No. 8-164840 is known. In the negative pressure control device described in the publication, the throttle valve is controlled to be closed when the throttle valve is in an idle opening and the intake pressure is larger than a predetermined value.
[0009]
[Problems to be solved by the invention]
However, when the above-mentioned air conditioner is further applied to the onboard internal combustion engine, in order to obtain the engine output necessary for driving the air conditioner, the fuel injection amount is normally set when the air conditioner is operating during stratified combustion. Larger than. As a result, in order to ensure a good combustion state, the throttle valve opening cannot be reduced, and the intake pressure of the in-vehicle internal combustion engine increases, so that the brake negative pressure necessary to drive the brake booster is reduced. It will not be possible to secure.
[0010]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a negative pressure control device for an in-vehicle internal combustion engine capable of obtaining a brake negative pressure required to drive a brake booster during stratified combustion. Is to provide.
[0011]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, the vehicle is driven by the rotation of the output shaft of the in-vehicle internal combustion engine capable of executing stratified combustion.Air conditionerWhen,During stratified combustionSaidAir conditionerMeans for increasing the fuel injection amount of the internal combustion engine when the engine is driven, a negative pressure generated in the intake system of the internal combustion engine is accumulated as a brake negative pressure, and a brake booster driven by the brake negative pressure; An intake air adjusting means for adjusting an intake air amount of the internal combustion engine; and an intake air amount of the internal combustion engine when the brake negative pressure does not reach a value necessary for operating the brake booster during stratified combustion.As long as the combustion state does not deteriorateWhen the control means for controlling the intake air adjusting means to reduce and the control of the intake air adjusting means by the control means,Air conditionerAnd stopping means for stopping the driving of the apparatus.
[0012]
  According to this configuration, in order to obtain the brake negative pressure required to drive the brake booster during stratified combustion of the on-vehicle internal combustion engine,Air conditionerThe intake air volume of the engine isAs long as the combustion state does not deteriorateIt will be reduced. That is,Air conditionerThus, the increase in the fuel injection amount based on the driving of the engine is eliminated, and the brake negative pressure required to drive the brake booster can be ensured even during the stratified combustion based on the decrease in the intake air amount.
[0013]
  According to a second aspect of the present invention, in the first aspect of the present invention, the stop means has an engine load of the internal combustion engine as the engine load.Air conditionerThe brake negative pressure for driving the brake booster can be secured only by controlling the intake air adjusting means by the control means without stopping the driving.Air conditionerThe drive was not stopped.
[0014]
  According to the configuration,Air conditionerWhen the brake negative pressure necessary to drive the brake booster is obtained by reducing the intake air amount without stopping the drive,Air conditionerBecause the drive is not stopped, it is unnecessary.Air conditionerIt is possible to prevent the drive from being stopped.
[0015]
  According to a third aspect of the present invention, in the first or second aspect of the invention, the internal combustion engine switches a combustion mode between stratified combustion and homogeneous combustion,Air conditionerWhen the driving means is necessary,Air conditionerThe stop prohibiting means for prohibiting the stop of driving and the stop prohibiting meansAir conditionerAnd combustion switching means for switching the combustion system of the internal combustion engine from stratified combustion to homogeneous combustion when the drive stop of the engine is prohibited.
[0016]
  According to this configuration, when the outside temperature is high,Air conditionerWhen the drive of the vehicle is required, the combustion system of the onboard internal combustion engine is switched from stratified combustion to homogeneous combustion, so that a brake negative pressure for driving the brake booster is secured. Therefore, stratified combustion improves the fuel consumption rate of the on-board internal combustion engine, and when necessaryAir conditionerIt is possible to prevent the drive of the engine from being stopped and to secure a brake negative pressure for driving the brake booster..
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an in-line four-cylinder automobile gasoline engine will be described with reference to FIGS.
[0018]
As shown in FIG. 1, the engine 11 includes a total of four pistons 12 (only one is shown in FIG. 1) provided in the cylinder block 11a so as to be reciprocally movable. The heads of these pistons 12 are formed with recesses 12a necessary for performing stratified combustion. The pistons 12 are connected to a crankshaft 14 that is an output shaft via a connecting rod 13. The reciprocating movement of the piston 12 is converted into rotation of the crankshaft 14 by the connecting rod 13.
[0019]
An air conditioner 29 for cooling the interior of the automobile is connected to the crankshaft 14. The air conditioner 29 is driven based on the rotation of the crankshaft 14 by operating the air conditioner switch 29a. A signal rotor 14 a is attached to the crankshaft 14. A plurality of protrusions 14b are provided on the outer periphery of the signal rotor 14a at equal angles with the axis of the crankshaft 14 as the center. A crank position sensor 14c is provided on the side of the signal rotor 14a. Then, when the crankshaft 14 rotates and each projection 14b of the signal rotor 14a sequentially passes the side of the crank position sensor 14c, the sensor 14c detects a pulse shape corresponding to the passage of each projection 14b. A signal is output.
[0020]
On the other hand, a cylinder head 15 is provided at the upper end of the cylinder block 11 a, and a combustion chamber 16 is provided between the cylinder head 15 and the piston 12. The combustion chamber 16 communicates with a pair of intake ports 17a, 17b provided in the cylinder head 15 and a pair of exhaust ports 18a, 18b (FIG. 1 shows one intake port 17b and one exhaust port). Only 18b is shown). The plane cross-sectional shapes of these intake and exhaust ports 17a, 17b, 18a, 18b are shown in FIG.
[0021]
As shown in the figure, the intake port 17a is a helical port that extends in a curved manner, and the intake port 17b is a straight port that extends in a straight line. When air passes through the intake port (helical port) 17 a and is sucked into the combustion chamber 16, a swirl is generated in the combustion chamber 16 in the direction indicated by the dashed arrow. An intake valve 19 and an exhaust valve 20 are provided in the intake ports 17a and 17b and the exhaust ports 18a and 18b, respectively.
[0022]
As shown in FIG. 1, the cylinder head 15 rotatably supports an intake cam shaft 21 and an exhaust cam shaft 22 for opening and closing the intake valve 19 and the exhaust valve 20. The intake and exhaust camshafts 21 and 22 are connected to the crankshaft 14 via timing belts and gears (both not shown), and the rotation of the crankshaft 14 is transmitted by the belts and gears. . When the intake camshaft 21 rotates, the intake valve 19 is driven to open and close, and the intake ports 17a and 17b and the combustion chamber 16 are communicated and disconnected. When the exhaust camshaft 22 rotates, the exhaust valve 20 is driven to open and close, and the exhaust ports 18a and 18b and the combustion chamber 16 are communicated and disconnected.
[0023]
In the cylinder head 15, a cam position sensor 21 b that detects a protrusion 21 a provided on the outer peripheral surface of the shaft 21 and outputs a detection signal is provided on the side of the intake camshaft 21. When the intake camshaft 21 rotates, the projection 21a of the shaft 21 passes the side of the cam position sensor 21b. In this state, detection signals are output from the cam position sensor 21b at predetermined intervals corresponding to the passage of the protrusion 21a.
[0024]
An intake pipe 30 and an exhaust pipe 31 are connected to the intake ports 17a and 17b and the exhaust ports 18a and 18b, respectively. An intake passage 32 is formed in the intake pipe 30 and the intake ports 17a and 17b, and an exhaust passage 33 is formed in the exhaust pipe 31 and the exhaust ports 18a and 18b. A throttle valve 23 is provided in the upstream portion of the intake passage 32. The throttle valve 23 is rotated by driving a throttle motor 24 composed of a direct current (DC) motor to adjust the opening degree. The opening of the throttle valve 23 is detected by a throttle position sensor 44.
[0025]
The driving of the throttle motor 24 is controlled based on the depression amount (accelerator depression amount) of an accelerator pedal 25 provided in the interior of the automobile. That is, when the driver of the automobile depresses the accelerator pedal 25, the accelerator depression amount is detected by the accelerator position sensor 26, and the throttle motor 24 is driven and controlled based on the detection signal of the sensor 26. By adjusting the opening of the throttle valve 23 based on the drive control of the throttle motor 24, the air flow area of the intake passage 32 changes, and the amount of air taken into the combustion chamber 16 is adjusted.
[0026]
A vacuum sensor 36 that detects the pressure in the passage 32 is provided in a portion of the intake passage 32 that is located downstream of the throttle valve 23. The vacuum sensor 36 outputs a detection signal corresponding to the detected pressure in the intake passage 32. A swirl control valve (SCV) 34 is provided in a portion of the intake passage 32 that is located downstream of the vacuum sensor 36 and communicates with the intake port (straight port) 17b. The SCV 34 is rotated by driving the swirl motor 35 to adjust the opening degree. As the opening of the SCV 34 becomes smaller, the amount of air passing through the intake port (helical port) 17a shown in FIG. 2 increases and the swirl generated in the combustion chamber 16 becomes stronger.
[0027]
Further, a brake booster 50 is connected to the intake passage 32 downstream of the throttle valve 23 via a negative pressure passage 49. The brake booster 50 is for reducing an operation force when the brake pedal 51 of the automobile is depressed, and is driven by using a negative pressure generated in the intake passage 32 when the engine 11 is operated. That is, air is sucked from the brake booster 50 through the negative pressure passage 49 by the negative pressure in the intake passage 32, and the booster 50 is based on the negative pressure (brake negative pressure Pb) generated in the brake booster 50 by the suction of the air. 50 is driven. The brake negative pressure Pb is detected by a booster pressure sensor 50a.
[0028]
As shown in FIG. 1, the cylinder head 15 has a fuel injection valve 40 that injects fuel into the combustion chamber 16, and a mixture of fuel and air filled in the combustion chamber 16. A spark plug 41 that performs ignition is provided. The ignition timing of the air-fuel mixture by the spark plug 41 is adjusted by an igniter 41 a provided above the spark plug 41. When the fuel is injected from the fuel injection valve 40 into the combustion chamber 16, the fuel is mixed with the air sucked into the combustion chamber 16 via the intake passage 32, and the air and fuel are mixed in the combustion chamber 16. An air-fuel mixture is formed. Further, the air-fuel mixture in the combustion chamber 16 is ignited by the spark plug 41 and combusted, and the air-fuel mixture after combustion is sent to the exhaust passage 33 as exhaust gas.
[0029]
Next, the electrical configuration of the negative pressure control device for the engine 11 in this embodiment will be described with reference to FIG.
This negative pressure control device includes an electronic control unit (hereinafter referred to as “ECU”) 92 for controlling the operating state of the engine 11 such as fuel injection amount control, ignition timing control, throttle opening control, and SCV opening control. I have. The ECU 92 is configured as a logical operation circuit including a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.
[0030]
Here, the ROM 93 is a memory in which various control programs and maps to be referred to when executing these various control programs are stored. The CPU 94 performs arithmetic processing based on the various control programs and maps stored in the ROM 93. Execute. The RAM 95 is a memory for temporarily storing calculation results in the CPU 94, data input from each sensor, and the like. The backup RAM 96 is a non-volatile memory for storing data to be saved when the engine 11 is stopped. The ROM 93, CPU 94, RAM 95, and backup RAM 96 are connected to each other via a bus 97 and are connected to an external input circuit 98 and an external output circuit 99.
[0031]
A crank position sensor 14c, a cam position sensor 21b, an accelerator position sensor 26, a vacuum sensor 36, a throttle position sensor 44, a booster pressure sensor 50a, and the like are connected to the external input circuit 98. On the other hand, the throttle motor 24, the air conditioner 29, the swirl motor 35, the fuel injection valve 40, the igniter 41a, and the like are connected to the external output circuit 99.
[0032]
The ECU 92 configured as described above obtains the intake pressure PM based on the detection signal from the vacuum sensor 36 and obtains the accelerator depression amount ACCP based on the detection signal from the accelerator position sensor 26. Further, the ECU 92 obtains the engine speed NE based on the detection signal from the crank position sensor 14c. Based on the intake pressure PM and the engine speed NE obtained as described above, or the accelerator depression amount ACCP and the engine speed NE, the basic fuel injection amount Qbse is calculated with reference to a known map. The basic fuel injection amount Qbse calculated in this way increases as the engine speed NE increases, and increases as the intake pressure PM or the accelerator depression amount ACCP increases.
[0033]
The engine load of the engine 11 is represented by the basic fuel injection amount Qbse. The ECU 92 sets the combustion method of the engine 11 to “homogeneous combustion” when the operating state of the engine 11 is in the high rotation and high load region, and sets the combustion method of the engine 11 to “ It is called “stratified combustion”. In this way, the combustion method is changed because the engine output is increased by setting the air-fuel ratio of the air-fuel mixture to the rich side during high rotation and high load where high output is required, and low rotation and low load that does not require very high output This is because sometimes the air-fuel ratio is set to a lean value to improve fuel efficiency.
[0034]
When the combustion method of the engine 11 is set to “homogeneous combustion”, the ECU 92 performs a map calculation on the basic fuel injection amount Qbse based on the intake pressure PM and the engine speed NE obtained based on the detection signal from the vacuum sensor 36. The ECU 92 controls the fuel injection valve 40 so that an amount of fuel corresponding to the final fuel injection amount Qfin obtained based on the basic fuel injection amount Qbse is injected from the fuel injection valve 40 during the intake stroke of the engine 11. . In the air-fuel mixture formed in the combustion chamber based on such fuel injection, the air-fuel ratio becomes a stoichiometric air-fuel ratio or a value larger than the stoichiometric air-fuel ratio. Further, the ECU 92 drives and controls the throttle motor 24, the igniter 41a, the swirl motor 35, and the like so that the throttle opening, the ignition timing, the opening of the SCV 34, and the like are suitable for “homogeneous combustion”.
[0035]
When the combustion method of the engine 11 is “stratified combustion”, the ECU 92 calculates the basic fuel injection amount Qbse from the accelerator depression amount ACCP and the engine speed NE. The ECU 92 injects fuel during the compression stroke of the engine 11 based on the final fuel injection amount Qfin obtained from the basic fuel injection amount Qbse. In the air-fuel mixture formed in the combustion chamber 16 by such fuel injection, the air-fuel ratio is set to a leaner value than the air-fuel ratio at the time of “homogeneous combustion”. Further, the ECU 92 drives and controls the throttle motor 24, the igniter 41a, the swirl motor 35, and the like so that the throttle opening degree, the ignition timing, the opening degree of the SCV 34, and the like are suitable for “stratified combustion”.
[0036]
During such “stratified combustion”, the fuel injected from the fuel injection valve 40 during the compression stroke of the engine 11 enters the recess 12 a (FIG. 1) provided in the head of the piston 12. Furthermore, a swirl is generated based on the opening degree adjustment of the SCV 34 by the drive control of the swirl motor 35, and the fuel is collected around the spark plug 41 by the movement of the swirl and the piston 12. By collecting the fuel around the spark plug 41 in this way, even if the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 is made larger than that during “homogeneous combustion”, the air-fuel ratio of the air-fuel mixture around the plug 41 is maintained. A good air-fuel mixture is ignited that is suitable for ignition. Further, in order to increase the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 as compared with “homogeneous combustion”, the throttle opening is controlled to the open side to increase the intake air amount. 11 pumping loss is reduced.
[0037]
Next, a procedure for calculating the final fuel injection amount Qfin during “stratified combustion” will be described with reference to FIG. FIG. 4 is a flowchart showing a final fuel injection amount calculation routine for calculating the final fuel injection amount Qfin. The final fuel injection amount calculation routine is executed through the ECU 92 by, for example, a time interruption every predetermined time.
[0038]
In the final fuel injection amount calculation routine, the ECU 92 determines whether or not “stratified combustion” is currently being performed as the process of step S101. If “stratified combustion” has not been performed, the final fuel injection amount calculation routine is temporarily terminated. If “stratified combustion” has been performed, the process proceeds to the subsequent step S102. The ECU 92 determines whether or not the air conditioner 29 is being driven as the process of step S102. If the air conditioner 29 is being driven, the process proceeds to step S103, and if the air conditioner 29 is not being driven, the process proceeds to step S104.
[0039]
The ECU 92 sets the air conditioner correction term Dac to the predetermined value a as the process of step S103, and sets the air conditioner correction term Dac to “0” as the process of step S104. The predetermined value a is variable according to the operating rate of the air conditioner 29. For example, the predetermined value a increases as the operating rate increases. Therefore, in a situation where the operation of the air conditioner 29 is required such as the outside air temperature becomes high, the predetermined value a becomes the maximum value when the operation rate of the air conditioner 29 reaches 100%. The air conditioning correction term Dac is used when calculating the correction amount Dcal in the subsequent process of step S105, and the correction amount Dcal is used when calculating the final fuel injection amount Qfin in the process of step S106.
[0040]
The ECU 92 calculates the correction amount Dcal in the process of step S105. The correction amount Dcal is for correcting the fuel injection amount of the engine 11 and is calculated by adding various correction terms such as an ISC (idle speed control) correction term Disc and an air conditioner correction term Dac. In step S106, the ECU 92 sets, as the final fuel injection amount Qfin, a value obtained by adding the correction amount Dcal to the basic fuel injection amount Qbse calculated from the accelerator depression amount ACCP and the engine speed NE. Thereafter, the ECU 92 once ends the final fuel injection amount calculation routine.
[0041]
When the final fuel injection amount Qfin is calculated in this way, the ECU 92 drives and controls the fuel injection valve 40 by another routine, and causes the fuel injection valve 40 to inject an amount of fuel corresponding to the final fuel injection amount Qfin. Accordingly, when the air conditioner 29 is being driven, the correction amount Dcal is increased by the amount of the air conditioner correction term Dac, and the final fuel injection amount Qfin is also compared to when the air conditioner 29 is not being driven. It will increase by the amount. By increasing the final fuel injection amount Qfin in this way, the engine speed NE is slightly increased and the output torque of the engine 11 is increased to a value necessary for driving the air conditioner 29.
[0042]
Next, a procedure for calculating the target throttle opening degree TAtrg used for throttle opening degree control during "stratified combustion" will be described with reference to FIGS. 5 and 6 are flow charts showing a target throttle opening calculation routine for calculating the target throttle opening TAtrg. This target throttle opening calculation routine is executed by the ECU 92 by, for example, a time interruption every predetermined time.
[0043]
In the target throttle opening calculation routine, the target throttle opening TAtrg is calculated by the processes of steps S117 and S118 (FIG. 5). That is, in the process of step S117, the ECU 92 calculates the basic throttle opening degree TAbse with reference to a known map based on the final fuel injection amount Qfin and the engine speed NE, and calculates the calculated basic throttle opening degree TAbse. Is set as the target throttle opening degree TAtrg. The basic throttle opening degree TAbse is calculated as a larger value as the final fuel injection amount Qfin and the engine speed NE increase.
[0044]
Next, in the process of step S118, the ECU 92 guards the target throttle opening degree TAtrg with a guard value G as a lower limit. The guard value G is set as a value that does not cause the combustion state of the engine 11 to deteriorate due to the throttle valve 23 being excessively closed.
[0045]
The ECU 92 performs the throttle motor 24 by another routine so that the value obtained by guarding the lower limit of the target throttle opening degree TAtrg calculated in this way and the actual throttle opening degree obtained based on the detection signal from the throttle position sensor 44 approach each other. Is controlled.
[0046]
Here, the relationship between the final fuel injection amount Qfin (engine load) and the guard value G of the target throttle opening degree TAtrg is shown in the graph of FIG. 7, and the relationship between the final fuel injection amount Qfin and the intake pressure PM that can be secured is shown in FIG. This is shown in the graph of FIG. As is apparent from these graphs, the guard value G of the target throttle opening degree TAtrg shown by the solid line in FIG. 7 increases as the final fuel injection amount Qfin increases under the condition that the accelerator depression amount ACCP is constant. In addition, the intake pressure PM that can be secured, which is indicated by a solid line in FIG.
[0047]
In the graph of FIG. 7, the alternate long and short dash line L1 indicates the target throttle opening degree TAtrg when the intake pressure PM (brake negative pressure Pb) necessary for driving the brake booster 50 is obtained. When the air conditioner 29 is not driven, the final fuel injection amount Qfin is reduced to, for example, a state indicated by a wavy line L2 in the figure, and the guard value G of the target throttle opening degree TAtrg is smaller than the one-dot chain line L1. In this case, the intake air amount of the engine 11 is small, and the intake pressure PM (brake negative pressure Pb) necessary to drive the brake booster 50 can be obtained.
[0048]
On the other hand, when the air conditioner 29 is driven, the final fuel injection amount Qfin is increased to a state indicated by a broken line L3 in the figure, for example, and the guard value G of the target throttle opening degree TAtrg is larger than the one-dot chain line L1. In this case, the intake air amount of the engine 11 is large, and the intake pressure PM (brake negative pressure Pb) necessary to drive the brake booster 50 cannot be obtained. Therefore, it can be seen from the graph of FIG. 7 that when the air conditioner 29 is driven, the intake pressure PM (brake negative pressure Pb) necessary to drive the brake booster 50 may not be obtained.
[0049]
Therefore, in this embodiment, when the brake negative pressure Pb necessary for driving the brake booster 50 cannot be obtained, the throttle opening is controlled to the closed side and the air conditioner 29 is driven. The drive of the shoner 29 is stopped. By stopping the operation of the air conditioner 29 in this way, the final fuel injection amount Qfin can be reduced to reduce the throttle opening, and the intake pressure PM and the brake negative pressure Pb are necessary for driving the brake booster 50. Value.
[0050]
In the target throttle opening calculation routine, in steps S103 to S106 (FIG. 6), when the brake negative pressure Pb is not a value necessary for driving the brake booster 50, the air conditioner 50 is driven to reduce the throttle opening. It is for stopping. Further, in steps S108 to S111, when the brake negative pressure Pb is not a value necessary for driving the brake booster 50, the correction amount r used for calculating the target throttle opening degree TAtrg is reduced so as to reduce the throttle opening degree. Is for. Further, the processing in steps S112 to S116 (FIG. 5) is performed to correct the throttle opening that has been reduced as described above when the brake negative pressure Pb has reached a value necessary for driving the brake booster 50. The amount r is gradually increased to “0”.
[0051]
In the target throttle opening calculation routine, the ECU 92 determines whether or not “stratified combustion” is currently being performed as the process of step S101 (FIG. 5). Then, if “stratified combustion” has not been performed, the target throttle opening degree calculation routine is once ended. If “stratified combustion” has been performed, the process proceeds to the subsequent step S102. In step S102, the ECU 92 obtains the brake negative pressure Pb based on the detection signal from the booster pressure sensor 50a, and the obtained brake negative pressure Pb reaches the required value Preq required to drive the brake booster 50. Determine whether or not.
[0052]
If it is determined in step S102 that the brake negative pressure Pb has not reached the required value Preq, the process proceeds to step S103 (FIG. 6). Thus, the process proceeds to step S103 when the intake pressure PM becomes high and the brake negative pressure Pb necessary for driving the brake booster 50 cannot be secured. The ECU 92 determines whether or not the air conditioner 29 is currently driven as the process of step S103. If the air conditioner 29 is not driven, the process proceeds to step S108.
[0053]
The ECU 92 determines whether or not “0” as the flag F is stored in a predetermined area of the RAM 95 in the process of step S108. This flag F is used to determine whether or not the control to the closing side of the throttle opening for securing the necessary brake negative pressure Pb has already been started. If it is determined that “F = 0” and the throttle closing control is not started, the process proceeds to step S109, and if it is determined that the throttle closing control is not started but “F = 0”. Proceed to step S110.
[0054]
The ECU 92 sets a value obtained by subtracting the predetermined value c from the correction amount r in the process of step S109 as a new correction amount r, and sets a value obtained by subtracting the predetermined value d from the correction amount r in the process of step S110. Set as r. The predetermined value d used in the process of step S110 is set to a value smaller than the predetermined value c used in the process of step S109. This correction amount r is used when the target throttle opening degree TAtrg is calculated in the process of step S117 (FIG. 5). The target throttle opening degree TAtrg increases as the correction amount r increases, and the target throttle opening degree TAtrg decreases as the correction amount r decreases.
[0055]
When the process proceeds from step S108 to step S109, “1” is stored in the predetermined area of the RAM 95 as the flag F in the process of step S111, and then the process proceeds to step S117. When the flag F is set to “1” in this way, NO is determined in the next process of step S108, and the process proceeds to step S110. If the process proceeds from step S108 to S110, the process directly proceeds to step S117.
[0056]
Therefore, immediately after the start of the throttle closing control, the target throttle opening degree TAtrg calculated by the process of step S117 is significantly reduced by reducing the correction amount r by the process of step S109. Thereafter, the correction amount r is gradually reduced by the processing of step S110, and the target throttle opening degree TAtrg is also gradually reduced. After the target throttle opening degree TAtrg is calculated in the process of step 117, the process proceeds to step S118.
[0057]
As a process of step S118, the ECU 92 performs a lower limit guard on the calculated target throttle opening degree TAtrg with the guard value G, and then ends this target throttle opening degree calculation routine once.
[0058]
As described above, when the air conditioner 29 is not driven and the brake negative pressure Pb is not a value necessary for driving the brake booster 50, the throttle valve 23 is closed by reducing the target throttle opening degree TAtrg. Controlled to the side. Thus, the throttle valve 23 is controlled to the closed side, whereby the intake pressure PM (brake negative pressure Pb) necessary for driving the brake booster 50 is ensured.
[0059]
On the other hand, if it is determined in the process of step S103 (FIG. 6) that the air conditioner 29 is currently driven, the process proceeds to step S104. Of the processes of steps S104 to S106, the process of step S106 is for stopping the operation of the air conditioner 29 in order to reduce the final fuel injection amount Qfin and the throttle opening. The process in step S104 is for determining whether or not the air conditioner 29 needs to be driven, such as when the outside air temperature is high and the difference between the outside air temperature and the room temperature is large. is there. Further, the process of step S105 determines whether or not the intake pressure PM (brake negative pressure Pb) necessary for driving the brake booster 50 can be secured without stopping the operation of the air conditioner 29 by the process of step S106. Is for.
[0060]
The ECU 92 determines whether or not the final fuel injection amount Qfin (engine load) is smaller than the determination value Q2 as the process of step S104. This determination value Q2 is set to a value corresponding to the final fuel injection amount Qfin (engine load) when the operating rate of the air conditioner 29 is set to “100%” because the outside air temperature is high, for example. When it is determined in the process of step S104 that the condition is that “Qfin <Q2” is not required and the air conditioner 29 needs to be driven, the process proceeds to step S107. By thus proceeding to step S107, execution of the drive stop process of the air conditioner 29 in step S106 is prohibited. In step S107, the ECU 92 switches the combustion method of the engine 11 from “stratified combustion” to “homogeneous combustion”, and then ends this target throttle opening calculation routine once. When switching to “homogeneous combustion” in this way, the throttle valve 23 is controlled to the closed side as compared to when “stratified combustion” is performed. As a result, even if the air conditioner 29 is driven, the intake pressure PM (brake negative pressure Pb) necessary for driving the brake booster 50 is ensured.
[0061]
If it is determined in the process of step S104 that “Qfin <Q2” and the air conditioner 29 is not necessarily driven, the process proceeds to step S105. The ECU 92 determines whether or not the final fuel injection amount Qfin (engine load) is larger than the determination value Q1 as the process of step S105. This determination value Q1 is set to a value corresponding to the final fuel injection amount Qfin (engine load) when the operating rate of the air conditioner 29 is low (for example, 10%). If it is determined in step S105 that “Qfin> Q1” is not satisfied, the process proceeds to step S108, where the processing after step S108 is executed, and the drive stop processing of the air conditioner 29 is executed in step S106. Never happen.
[0062]
When the operating rate of the air conditioner 29 is low and the final fuel injection amount Qfin is relatively small (“Qfin <Q1”), the guard value G of the target throttle opening degree TAtrg becomes the one-dot chain line L1 as shown in FIG. It is close. Therefore, the target throttle opening degree TAtrg can be made to reach the one-dot chain line L1 only by closing control of the throttle valve 23 based on the processing in steps S108 to S111 without stopping the operation of the air conditioner 29. The brake negative pressure Pb necessary for driving the brake booster 50 can be obtained only by controlling the closing of the throttle valve 23, and the air conditioner 29 can be prevented from being unnecessarily stopped. .
[0063]
If it is determined in the process of step S105 that “Qfin> Q1”, the process proceeds to step S106. Thus, when the routine proceeds to step S106, the final fuel injection amount Qfin is a magnitude between the judgment value Q1 and the judgment value Q2. The ECU 92 stops driving the air conditioner 29 as the process of step S106. By stopping the operation of the air conditioner 29 in this way, even if the final fuel injection amount Qfin is in the state indicated by the broken line L3 between the judgment value Q1 and the judgment value Q2 shown in FIG. It changes to the decreasing side (left side in the figure).
[0064]
Further, after the process of step S106 is performed, the closing control of the throttle valve 23 based on the processes of steps S108 to S111 and the like is performed. As a result, the target throttle opening degree TAtrg calculated by the processing in steps S117 and S118 (FIG. 5) becomes a value smaller than the one-dot chain line L1 in FIG. 7, and the intake pressure PM (brake negative pressure) required for driving the brake booster 50 is obtained. The pressure Pb) is ensured.
[0065]
When the brake negative pressure Pb necessary for driving the brake booster 50 is secured by stopping the driving of the air conditioner 29 or controlling the closing of the throttle valve 23 as described above, the process of step S102 is performed. It will be judged as YES. That is, in the process of step S102, it is determined that the brake negative pressure Pb has reached the required value Preq, and the process proceeds to step S112.
[0066]
In step S112, the ECU 92 determines whether or not “1” as the flag F is stored in a predetermined area of the RAM 95, that is, whether or not the throttle closing control for securing the necessary brake negative pressure Pb is being performed. . Immediately after the brake negative pressure Pb reaches the required value Preq as described above, since “F = 1”, YES is determined in the process of step S112 and the process proceeds to step S113. The ECU 92 determines whether or not the correction amount r is smaller than “0” as the process of step S113. If “r <0”, the ECU 92 sets the predetermined correction value e to the current correction amount r in the subsequent process of step S114. The added value is set as a new correction amount r.
[0067]
Therefore, when the brake negative pressure Pb reaches the required value Preq, the correction amount r is gradually increased by the process of step S114, and the target throttle opening degree TAtrg calculated by the process of step S117 is gradually increased. Thus, when the target throttle opening degree TAtrg is gradually increased, the throttle valve 23 is also gradually controlled to open. If “r ≧ 0” is obtained by gradually increasing the correction amount r in the process of step S114, NO is determined in the process of step S113, and the process proceeds to step S115.
[0068]
The ECU 92 sets the correction amount r to “0” as the process of step S115, and sets the flag F to “0” as the process of step S116. By setting “F = 0” in this way, the next step S112 is determined to be NO in step S112, and the processing after step S115 is executed. Then, by returning the correction amount r to “0” as described above, the throttle valve 23 that has been controlled to the closed side in order to secure the necessary brake negative pressure Pb is restored.
[0069]
Finally, the operation of the negative pressure control device in this embodiment will be summarized with reference to the graph of FIG. FIG. 9 shows the transitions of the intake pressure PM and the brake negative pressure Pb when the throttle closing control is executed during “stratified combustion”, separately for when the air conditioner 29 is driven and when it is not driven. is there.
[0070]
When the brake negative pressure Pb that changes as indicated by two-dot chain lines L4 and L5 in the figure becomes a value on the atmospheric pressure side than the required value Preq indicated by the one-dot chain line L6, the closing control of the throttle valve 23 is executed. When the air conditioner 29 is not being driven, the intake pressure PM decreases as indicated by the broken line L8 and reaches the required value Preq due to the closing control of the throttle valve 23. The brake negative pressure Pb approaches the intake pressure PM that changes as indicated by the broken line L8 after the start of the closing control of the throttle valve 23, and finally changes in agreement with the intake pressure PM. Therefore, when the air conditioner 29 is not driven, the brake negative pressure Pb reaches the required value Preq by the throttle closing control, and becomes a value necessary for driving the brake booster 50.
[0071]
However, when the air conditioner 29 is being driven, the intake pressure PM decreases as indicated by the solid line L7 due to the throttle closing control, but does not reach the required value Preq. Even in this state, the brake negative pressure Pb approaches the intake pressure PM that changes as indicated by the solid line L7 after the start of the throttle closing control, and changes to coincide with the intake pressure PM of the final enemy. Therefore, when the air conditioner 29 is driven, the brake negative pressure Pb does not reach the required value Preq even if the throttle closing control is performed, and the brake negative pressure Pb necessary for driving the brake booster 50 is ensured. I can't.
[0072]
Therefore, in the present embodiment, when the throttle closing control for securing the brake negative pressure Pb is performed, if the air conditioner 29 is driven, the air conditioner 29 is forcibly stopped. By thus stopping the operation of the air conditioner 29, the transition tendency of the intake pressure PM during the throttle closing control changes from the state indicated by the solid line L7 in FIG. 9 to the state indicated by the broken line L8, and the brake negative pressure is controlled by the throttle closing control. Pb reaches the required value Preq. Accordingly, even during “stratified combustion”, the brake negative pressure Pb (intake pressure PM) necessary to drive the brake booster 50 based on the throttle closing control can be secured.
[0073]
According to the present embodiment in which the processing detailed above is performed, the following effects can be obtained.
(1) During the “stratified combustion”, when the brake negative pressure Pb necessary for driving the brake booster 50 is ensured, the throttle closing control is performed with the air conditioner 29 stopped driving. Accordingly, the final fuel injection amount Qfin based on the driving of the air conditioner 29 is not increased, and the brake negative pressure Pb necessary for driving the brake booster 50 can be secured by the throttle closing control even during “stratified combustion”. . Also, during idling while the vehicle is stopped or when the vehicle is traveling at an extremely low speed, the intake pressure PM becomes a relatively high value and the necessary brake negative pressure Pb is ensured during “stratified combustion”. Hard to do. However, by executing the drive stop process of the air conditioner 29, the necessary brake negative pressure Pb can be accurately ensured even in the above driving situation.
[0074]
(2) When the operating rate of the air conditioner 29 is low and the final fuel injection amount Qfin (engine load) is smaller than the judgment value Q1, the brake booster 50 is driven only by throttle closing control even if the air conditioner 29 is driven. Therefore, it is possible to secure the brake negative pressure Pb necessary for the operation. Therefore, when “Qfin <Q1”, the air conditioner 29 is not stopped for securing the brake negative pressure Pb required at the time of “stratified combustion”, and the brake negative pressure Pb is controlled only by throttle closing control. Make sure. Therefore, it is possible to prevent the air conditioner 29 from being stopped unnecessarily.
[0075]
(3) When the operating rate of the air conditioner 29 is high such as when the outside air temperature is high and the final fuel injection amount Qfin (engine load) is larger than the judgment value Q2, it is determined that the air conditioner 29 needs to be driven. Is done. In this situation, the necessary brake negative pressure Pb during “stratified combustion” is secured by switching the combustion system from “stratified combustion” to “homogeneous combustion” while the air conditioner 29 is prohibited from being stopped. Done. Accordingly, the fuel consumption rate of the engine 11 is improved by “stratified combustion”, the air conditioner 29 is prevented from being stopped when necessary, and the brake negative pressure Pb necessary for driving the brake booster 50 is reduced. Can be secured.
[0076]
In addition, this embodiment can also be changed as follows, for example.
Although it is determined that the air conditioner 29 needs to be driven based on the final fuel injection amount Qfin (engine load) being larger than the determination value Q2, the present invention is not limited to this. That is, for example, the outside air temperature and the room temperature may be measured, and it may be determined that the air conditioner 29 needs to be driven when the difference between them is large.
[0077]
The determination value Q2 for determining whether or not the air conditioner 29 needs to be driven may be changed as appropriate.
・ When the air conditioner 29 needs to be driven, the air conditioner 29 is prohibited from being stopped, and the combustion system is switched from “stratified combustion” to “homogeneous combustion”, and the brake required to drive the brake booster 50. Although the negative pressure Pb is secured, such a process is not necessarily performed.
[0078]
In the target throttle opening calculation routine, the determination value Q1 used in the process of step S104 (FIG. 6) may be changed as appropriate.
If the required brake negative pressure Pb can be obtained only by throttle closing control without stopping the operation of the air conditioner 29, that is, if the final fuel injection amount Qfin is smaller than the judgment value Q1, the air conditioner Although the driving of the shoner 29 is stopped, such processing is not necessarily performed. For example, when the throttle closing control for ensuring the brake negative pressure Pb is performed, the driving of the air conditioner 29 may be stopped without fail.
[0079]
Although the intake pressure PM and the brake negative pressure Pb are secured by reducing the intake air amount based on the closing control of the throttle valve 23, the present invention is not limited to this. That is, when the engine 11 is applied with a bypass passage that bypasses the throttle valve 23 and is connected to the intake passage 32 and an idle speed control valve that adjusts the air flow rate in the bypass passage, the idle speed control valve The intake pressure PM and the brake negative pressure Pb may be secured by reducing the intake air amount based on the closing control.
[0080]
【The invention's effect】
  According to the first aspect of the present invention, in order to obtain the brake negative pressure necessary for driving the brake booster during the stratified combustion of the in-vehicle internal combustion engine,Air conditionerThe intake air amount of the engine is reduced in a state where the driving of is stopped. That is,Air conditionerAccordingly, the increase in the fuel injection amount based on the driving of the engine is eliminated, and the brake negative pressure required to drive the brake booster can be secured even during the stratified combustion based on the decrease in the intake air amount.
[0081]
  According to invention of Claim 2,Air conditionerWhen the brake negative pressure necessary to drive the brake booster is obtained by reducing the intake air amount without stopping the drive,Air conditionerBecause the drive is not stopped, it is unnecessary.Air conditionerCan be prevented from being stopped.
[0082]
  According to the invention of claim 3, when the outside air temperature is high, etc.Air conditionerWhen the drive of the vehicle is required, the combustion system of the onboard internal combustion engine is switched from stratified combustion to homogeneous combustion, so that a brake negative pressure for driving the brake booster is secured. Therefore, stratified combustion improves the fuel consumption rate of the on-board internal combustion engine, and when necessaryAir conditionerCan be stopped, and a brake negative pressure for driving the brake booster can be secured..
[Brief description of the drawings]
FIG. 1 is a sectional view showing an entire engine to which a negative pressure control apparatus according to the present invention is applied.
FIG. 2 is a cross-sectional view of a cylinder head showing the shape of intake and exhaust ports in the engine.
FIG. 3 is a block diagram showing an electrical configuration of the control device.
FIG. 4 is a flowchart showing a final fuel injection amount calculation procedure.
FIG. 5 is a flowchart showing a target throttle opening calculation procedure.
FIG. 6 is a flowchart showing a target throttle opening calculation procedure.
FIG. 7 is a graph showing the relationship between the final fuel injection amount and the guard value of the target throttle opening.
FIG. 8 is a graph showing the relationship between the final fuel injection amount and the intake pressure that can be secured.
FIG. 9 is a graph showing the transition of the intake pressure and the brake negative pressure when the throttle closing control is executed during “stratified combustion”, separately when the air conditioner is driven and when it is not driven.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine, 14 ... Crankshaft, 23 ... Throttle valve, 24 ... Throttle motor, 29 ... Air conditioner, 32 ... Intake passage, 34 ... Swirl control valve (SCV), 35 ... Swirl motor, 36 ... Vacuum sensor , 40 ... Fuel injection valve, 44 ... Throttle position sensor, 49 ... Negative pressure passage, 50 ... Brake booster, 50a ... Booster pressure sensor, 92 ... Electronic control unit (ECU).

Claims (3)

An air conditioner driven by rotation of an output shaft of an on-vehicle internal combustion engine capable of executing stratified combustion;
Means for increasing the fuel injection amount of the internal combustion engine when the air conditioner is driven during stratified combustion ;
A brake booster that accumulates the negative pressure generated in the intake system of the internal combustion engine as a brake negative pressure, and is driven by the brake negative pressure;
Intake air adjusting means for adjusting the intake air amount of the internal combustion engine;
When the brake negative pressure does not reach a value necessary for operating the brake booster during stratified combustion, the intake air adjustment is performed to reduce the intake air amount of the internal combustion engine within a range in which the combustion state does not deteriorate. Control means for controlling the means;
Stop means for stopping the driving of the air conditioner when the control of the intake air adjusting means is performed by the control means;
A negative pressure control device for an in-vehicle internal combustion engine, comprising: When the engine load of the internal combustion engine is a value that can secure a brake negative pressure for driving the brake booster only by the control of the intake air adjusting means by the control means without stopping the operation of the air conditioner. The negative pressure control device for an in-vehicle internal combustion engine according to claim 1, wherein driving of the air conditioner is not stopped. The negative pressure control device for an on-vehicle internal combustion engine according to claim 1 or 2,
The internal combustion engine switches a combustion method between stratified combustion and homogeneous combustion, and prohibits the air conditioner from being stopped by the stopping means when the air conditioner needs to be driven. Further comprising: stop prohibiting means; and combustion switching means for switching the combustion system of the internal combustion engine from stratified combustion to homogeneous combustion when the stop of the operation of the air conditioner is prohibited by the stop prohibiting means. Negative pressure control device for in-vehicle internal combustion engine.

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