JP2007187168A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of realizing control for keeping a balance between an improvement in a catalytic warming-up performance and security of brake performance. <P>SOLUTION: This control device is mounted on a vehicle having a brake booster 32 with suction negative pressure of an internal combustion engine as a boosting source, and controls an ignition timing delay of the ignition timing when put in a predetermined operation state, and has a booster state monitoring means for monitoring a brake booster state when performing ignition timing delay control and a negative pressure recovery control means for eliminating a shortage of negative pressure by controlling a control parameter for changing an operation state of the internal combustion engine when detecting the shortage of the negative pressure by its booster state monitoring means, and is constituted so that its negative pressure recovery control means temporarily stops operation of an electric load of the internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine mounted on a vehicle including a brake booster that uses a suction negative pressure of the internal combustion engine as a boosting source.

  In recent years, in internal combustion engines, ignition timing retardation control is being introduced to improve the warm-up performance of a catalyst provided in an exhaust passage in order to purify exhaust gas. This is because if the ignition timing is retarded, the combustion end timing and combustion speed are delayed and exhaust heat loss increases, and as a result, high-temperature exhaust gas is supplied to the catalyst, and early warm-up of the catalyst is realized. It is based on. Since the retard of the ignition timing is accompanied by a decrease in engine torque, generally, when executing such an ignition timing retard control, a control for increasing the intake air amount is simultaneously performed in order to prevent a decrease in engine torque. (For example, refer to Patent Document 1 below).

  On the other hand, in a vehicle, a brake booster is widely employed in order to reduce the operating force of a brake pedal during braking. In general, the brake booster uses a suction negative pressure of the engine as a boosting source. Therefore, when the intake air amount is increased in response to the ignition timing retard control for warming up the catalyst, the throttle valve is opened and the absolute value of the intake pipe negative pressure decreases (approaches atmospheric pressure). Therefore, the brake performance may be reduced.

Japanese Patent Laid-Open No. 11-107822

  The present invention has been made in view of the above-described problems, and an object of the present invention is to control an internal combustion engine capable of realizing control that achieves a balance between improvement in catalyst warm-up performance and ensuring of brake performance. To provide an apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, when mounted on a vehicle equipped with a brake booster using a suction negative pressure of an internal combustion engine as a boosting source and in a predetermined operating state And a booster state monitoring means for monitoring the state of the brake booster during the execution of the ignition timing retardation control, and a negative pressure shortage by the booster state monitoring means. There is provided a control apparatus for an internal combustion engine, comprising: negative pressure recovery control means for controlling a control parameter that changes the operating state of the internal combustion engine to eliminate the shortage of negative pressure when the engine is detected.

  According to a second aspect of the present invention, in the apparatus according to the first aspect, the negative pressure recovery control means controls at least one of an intake air amount or an ignition timing of the internal combustion engine. It is.

  According to a third aspect of the present invention, in the apparatus according to the second aspect, the negative pressure recovery control means calculates a throttle opening degree that achieves the required negative pressure, and sucks from the throttle opening degree. The amount of air is estimated, the ignition timing retardation amount is calculated from the amount of intake air and the torque necessary to maintain idle rotation, and the amount of intake air and ignition timing are controlled.

  According to the fourth aspect of the present invention, in the apparatus according to the third aspect, the required negative pressure is determined according to the booster operating time.

  According to a fifth aspect of the present invention, in the apparatus according to the second aspect, the negative pressure recovery control means stops the ignition timing retardation control when the booster operating time exceeds a predetermined time. Then, the throttle opening that can realize the torque required to maintain the idle rotation is calculated, and the intake air amount and the ignition timing are controlled.

  According to a sixth aspect of the present invention, in the apparatus according to the first aspect, the negative pressure recovery control means temporarily stops the operation of the electric load of the internal combustion engine.

  Further, according to a seventh aspect of the present invention, in the apparatus according to the sixth aspect, the negative pressure recovery control means is further provided when the shortage of negative pressure is not eliminated even by stopping the operation of the electric load. As the negative pressure recovery control, at least one of the intake air amount or ignition timing of the internal combustion engine is controlled.

  Further, according to an eighth aspect of the present invention, in the apparatus according to the first aspect, the negative pressure recovery control means takes the intake air when the intake valve timing of the internal combustion engine is set to the most retarded position. The valve timing is advanced by a predetermined amount.

  Further, according to a ninth aspect of the present invention, in the apparatus according to the eighth aspect, the negative pressure recovery control means is further configured when the shortage of negative pressure is not resolved even by the advance angle of the intake valve timing. As the negative pressure recovery control, at least one of the intake air amount or ignition timing of the internal combustion engine is controlled.

  According to a tenth aspect of the present invention, in the apparatus according to the first aspect, when the negative pressure recovery control means has a transmission in the vehicle drive system, the transmission is moved to the low speed stage side. To shift.

  According to the eleventh aspect of the present invention, in the apparatus according to the tenth aspect, the negative pressure recovery control means is configured such that the shortage of negative pressure is not eliminated even by shifting the transmission to the low speed stage side. In addition, as further negative pressure recovery control, at least one of the intake air amount and the ignition timing of the internal combustion engine is controlled.

  According to a twelfth aspect of the present invention, in the device according to the seventh, ninth, or eleventh aspect, the further negative pressure recovery control calculates a throttle opening degree that achieves the required negative pressure. The intake air amount is estimated from the throttle opening, the ignition timing retard amount is calculated from the intake air amount and the torque necessary to maintain idle rotation, and the intake air amount and the ignition timing are controlled. It is.

  According to a thirteenth aspect of the present invention, in the apparatus according to the second aspect, the booster state monitoring means also monitors the operation amount and the operation speed of the booster, and the negative pressure recovery control The means calculates a required negative pressure from the operating amount and the operating speed, calculates a throttle opening for achieving the required negative pressure, estimates an intake air amount from the throttle opening, The ignition timing retard amount is calculated from the torque required to maintain idle rotation, and the intake air amount and ignition timing are controlled.

  According to a fourteenth aspect of the present invention, there is provided a control device for an internal combustion engine mounted on a vehicle equipped with a brake booster that uses a suction negative pressure of the internal combustion engine as a boosting source, from the operating state of the brake booster. Target braking force calculating means for calculating a target braking force, braking force determining means for determining whether or not the braking force is insufficient based on the target braking force calculated by the target braking force calculating means, and the braking force When it is determined by the determination means that the braking force is insufficient, at least one of the intake air amount or the ignition timing of the internal combustion engine is changed to increase the negative suction pressure of the internal combustion engine, thereby increasing the braking force. There is provided a control device for an internal combustion engine, comprising braking force recovery control means for eliminating the shortage.

  According to a fifteenth aspect of the present invention, in the apparatus according to the fourteenth aspect, the braking force determination means includes a target braking force calculated by the target braking force calculation means and a negative pressure of the brake booster. Is determined based on the deviation from the realizable braking force estimated from the above.

  According to a sixteenth aspect of the present invention, in the apparatus according to the fourteenth aspect, the braking force determining means is based on the target braking force calculated by the target braking force calculating means and the change state of the vehicle speed. The lack of braking force is determined based on the deviation from the estimated actual braking force.

  According to a seventeenth aspect of the present invention, in the device according to the fifteenth or sixteenth aspect, the braking force recovery control means calculates a required negative pressure from the deviation and achieves the required negative pressure. The throttle opening is calculated, the intake air amount is estimated from the throttle opening, the ignition timing retard amount is calculated from the intake air amount and the torque necessary to maintain idle rotation, and the intake air amount And controls ignition timing.

  According to an eighteenth aspect of the present invention, in the device according to the fifteenth or sixteenth aspect, the braking force recovery control means controls the ignition timing by calculating an ignition timing retardation amount from the deviation. To do.

  According to a nineteenth aspect of the present invention, in the device according to the fifteenth aspect, the realizable braking force is estimated in consideration of the driving torque in addition to the negative pressure of the brake booster.

  According to the twentieth aspect of the present invention, in the apparatus according to each of the above aspects, the abnormality of the sensor system is detected, and when the abnormality is detected, the intake air amount and / or the ignition timing is controlled normally. An abnormality processing means for returning to control is further provided.

  According to the present invention, control that achieves a balance between improvement in catalyst warm-up performance and ensuring of brake performance is realized.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is an overall schematic diagram of an internal combustion engine (engine) provided with a control device according to the present invention. The engine 10 is an in-line multi-cylinder four-stroke cycle reciprocating gasoline engine mounted on a vehicle. An intake passage 12 is connected to the intake port of the engine 10, and an air cleaner 14, a throttle valve 16, a surge tank 18, an intake manifold 20, and the like are provided in the intake passage 12. The throttle valve 16 in the present embodiment is a so-called electronic throttle, and is driven by the throttle motor 17 without being mechanically coupled directly to the accelerator pedal of the driver's seat.

  Air outside the engine 10 (outside air) sequentially passes through the portions 14, 16, 18, and 20 of the intake passage 12 toward the combustion chamber in the cylinder. An injector 22 that injects fuel toward each intake port is attached to the intake manifold 20. In order to ignite the air-fuel mixture in the cylinder, a spark plug 24 is attached to the cylinder head. The combusted air-fuel mixture is discharged from the exhaust port to the atmosphere through the exhaust passage 26 including the exhaust manifold 28, the catalytic converter 30, and the like.

  The brake booster 32 is a device for reducing the force required to operate the brake pedal 34, and obtains the boost source from the suction negative pressure in the surge tank 18. When the brake pedal 34 is operated, the brake switch (stop switch) 36 is closed and the stop lamp 38 is lit.

  Various sensors are attached to the vehicle. Of these, sensors related to each embodiment will be described. First, a crank angle sensor 40 that generates a rotation speed detection pulse for detecting the rotation speed (rotation speed) of the crankshaft is provided. Further, a vehicle speed sensor 44 that generates a number of output pulses per unit time in proportion to the rotational speed of the output shaft of the transmission 42, that is, the vehicle speed SPD is attached.

  An intake pressure sensor 46 for detecting the pressure inside the surge tank 18 is attached. In the intake passage 12, in the vicinity of the throttle valve 16, a throttle opening sensor 48 for detecting the rotation angle of the shaft and an accelerator opening sensor 50 for detecting an accelerator depression amount (accelerator opening) are provided. .

  The brake booster 32 is provided with a brake booster pressure sensor 52 that detects the pressure of the portion communicating with the surge tank 18. Further, in some embodiments described later, it is assumed that a brake sensor 54 that detects the brake depression amount is provided in the vicinity of the brake pedal 34.

  Some embodiments described later are based on a vehicle on which an air conditioner (air conditioner) 56 as an electric load of the internal combustion engine is mounted. The air conditioner is provided with a compressor for compressing the refrigerant gas, and the compressor is connected to the crankshaft pulley of the engine via a belt. Therefore, if the air conditioner is turned on, the engine load increases. In another embodiment, an engine provided with a variable valve timing (VVT) mechanism 58 for changing the opening / closing timing of the intake valve is assumed. In yet another embodiment, it is assumed that the transmission (transmission) 42 is an electronically controlled automatic transmission.

  The control device 60 is a microcomputer system that performs fuel injection control, ignition timing control, etc., receives signals from various sensors, performs arithmetic processing based on the input signals, and performs the injector 22 based on the calculation results. The control signal for the spark plug 24 and the like is output. Further, the control device 60 controls other control parameters that change the operation state of the internal combustion engine.

  Hereinafter, each embodiment related to control by the control device 60 that achieves a balance between improvement in catalyst warm-up property and ensuring of brake performance will be described. FIG. 2 is a flowchart showing a processing procedure of a brake control execution condition flag operation routine according to the first embodiment of the present invention, and FIG. 3 is a processing procedure of a catalyst warm-up delay amount calculation routine according to the first embodiment. It is a flowchart which shows. Both routines are executed in the control device 60 at predetermined time intervals.

  In the brake control execution condition flag operation routine of FIG. 2, first, at step 102, ignition timing retarding control for improving the warm-up property of the catalytic converter 30 provided in the exhaust passage 26 to purify the exhaust gas is performed. It is determined whether or not it is being executed. As described above, the catalyst warm-up delay angle control retards the ignition timing in order to improve the warm-up performance of the catalyst in the cold state, and increases the retard amount in order to maintain the idling speed. Accordingly, since the control for increasing the intake air amount is simultaneously performed, the absolute value of the negative pressure of the brake booster 32 may be lowered. If the retard control is being executed, the process proceeds to step 104. If not, the process proceeds to step 114.

In Step 104, the negative pressure PBK detected by the brake booster pressure sensor 52 is compared with a reference value P ₀ (for example, −26.6 kPa (= −200 mmHg)), and when PBK> P ₀ , that is, the negative pressure is insufficient. If it is determined that the negative pressure is sufficient, the process proceeds to step 106. If PBK ≦ P ₀ , that is, if it is determined that the negative pressure is sufficient, the process proceeds to step 114.

In step 106, it is determined whether or not the signal BKSW from the brake switch 36 is ON. When it is ON, the process proceeds to step 108, and when it is OFF, the process proceeds to step 114. In step 108, the vehicle speed SPD calculated based on the output of the vehicle speed sensor 44 is compared with a reference value S ₀ (for example, 40 km / h). When SPD> S ₀ , the process proceeds to step 110, while SPD ≦ S ₀ . Sometimes go to step 114.

  In step 110, it is determined whether or not the idle ON flag EXIDL (set to ON when it is determined that the engine is in an idle state based on the output of the accelerator opening sensor 50) is ON. On the other hand, the process proceeds to step 112. If it is OFF, the process proceeds to step 114.

  In step 112, which is executed when the determination results of steps 102, 104, 106, 108 and 110 are all YES, a brake control execution condition flag EXBK indicating that engine control in consideration of brake performance is to be executed is set. 1 is set. On the other hand, in step 114, which is executed when the determination result of any of steps 102, 104, 106, 108 or 110 is NO, it is determined that it is not necessary to execute engine control in consideration of brake performance. Therefore, 0 is set to the brake control execution condition flag EXBK.

  In the catalyst warm-up retard amount calculation routine shown in FIG. 3, first, it is determined in step 152 whether or not the brake control execution condition flag EXBK is 1. When EXBK = 1, the process proceeds to step 154, while EXBK = When it is 0, this routine is terminated.

  In step 154, the throttle opening degree that achieves the required negative pressure (for example, −39.9 kPa (= −300 mmHg)) under the current engine speed is calculated. For this calculation, a map for obtaining the throttle opening from the engine speed and the required negative pressure is stored in advance in a memory in the control device 60. Then, the throttle motor 17 is controlled by another control routine so that the opening degree of the throttle valve 16 detected by the throttle opening degree sensor 48 becomes the calculated throttle opening degree.

  Next, at step 156, the intake air amount is estimated from the throttle opening calculated at step 154. For this estimation, a map for obtaining the intake air amount from the throttle opening degree is stored in advance in a memory in the control device 60.

  In the final step 158, the catalyst warm-up retardation amount is calculated from the intake air amount estimated in step 156 and the idle rotation maintenance torque (torque required to maintain idle rotation) that is separately obtained. The For this calculation, a map in which the catalyst warm-up delay amount is determined according to the intake air amount and the idle rotation maintenance torque is stored in advance in the memory in the control device 60. The catalyst warm-up delay amount is determined by the basic ignition timing (crank angle from the compression top dead center to the advance angle) determined from the engine speed and the engine load (for example, the intake pipe pressure detected by the intake pressure sensor 46). Used as a subtraction amount for the counted value (ignition advance value)).

  With the above-described control, it is possible to sufficiently ensure the performance of the booster using the intake pipe negative pressure while suppressing a decrease in the engine torque for warming up the catalyst. In addition, in order to enable torque control at the time of transient operation by ignition timing, control for temporarily setting the ignition timing in the idle state (transient correction idle retardation control) may be performed. Since the control for increasing the intake air amount according to the retard amount is simultaneously performed in order to maintain the idling speed, the negative pressure of the brake booster 32 may be reduced. The same control as the brake control for the catalyst warm-up delay angle control described above can be applied to the transient correction idle delay angle control. The same applies to the embodiments described below.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the same routine as the brake control execution condition flag operation routine (FIG. 2) in the first embodiment is executed, and the catalyst warm-up retardation amount calculation routine shown in FIG. 4 is executed. . The contents of steps 252, 256, 258 and 260 in FIG. 4 are the same as the contents of steps 152, 154, 156 and 158 in the catalyst warm-up retard amount calculation routine (FIG. 3) according to the first embodiment, respectively.

  In the first embodiment, the required negative pressure is a constant value. In the second embodiment, the ON time of the signal BKSW from the brake switch 36 is obtained, and the required negative pressure corresponding to the ON time is obtained. Is calculated (step 254). For this calculation, a map as shown in FIG. 5A or 5B is stored in advance in a memory in the control device 60. Since the negative pressure in the booster is consumed more as the BKSW ON time is longer, in these maps, the required negative pressure is set lower as the BKSW ON time is longer. Thus, in the second embodiment, it is possible to suppress a decrease in engine torque to a smaller extent than in the first embodiment.

  Next, a third embodiment of the present invention will be described. FIG. 6 is a flowchart showing a processing procedure of a brake control execution condition flag operation routine according to the third embodiment, and FIG. 7 is a flowchart showing a processing procedure of a throttle opening degree calculation routine according to the third embodiment. The contents of steps 302, 304, 308, 310, 312 and 314 in FIG. 6 are the same as the steps 102, 104, 108, 110, 112 and 114 of the brake control execution condition flag operation routine (FIG. 2) according to the first embodiment. Each content is the same.

  On the other hand, in step 106 in FIG. 2, it is determined whether or not the signal BKSW from the brake switch 36 is ON, whereas in the corresponding step 306 in FIG. 6, the signal BKSW from the brake switch 36 is ON. It is determined whether or not a certain period of time (ie, booster operating time) has elapsed. Therefore, according to the brake control execution condition flag operation routine of FIG. 6, the brake control execution condition flag EXBK is set to 1 only when a reliable brake operation is performed.

  In the throttle opening calculation routine of FIG. 7, first, it is determined in step 352 whether or not the brake control execution condition flag EXBK is 1. When EXBK = 1, the process proceeds to step 354, while when EXBK = 0. This routine ends. In step 354, the execution of the catalyst warm-up delay angle control is stopped, and the normal required ignition timing in a state where the catalyst warm-up delay angle control is not performed is calculated. Next, at step 356, the throttle valve 16 is controlled by setting a throttle opening that can realize the idle rotation maintaining torque. Thus, when a reliable brake operation is performed, ensuring the brake performance is emphasized, the catalyst warm-up delay angle control is stopped, and the idle rotation is maintained.

  Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the same routine as the brake control execution condition flag operation routine (FIG. 2) in the first embodiment is executed, and the air conditioner operation routine shown in FIG. 8 is executed. In the state where the electric load of the internal combustion engine such as the air conditioner 56 is turned on, the intake air amount is increased as compared with the off state. Therefore, in the fourth embodiment, the shortage of negative pressure is solved by temporarily stopping the operation of the air conditioner 56.

  That is, in the air conditioner operation routine of FIG. 8, first, in step 452, it is determined whether or not the flag EXAC that is ON when the air conditioner 56 is operating is ON. When EXAC = ON, the process proceeds to step 454. This routine ends when EXAC = OFF. In step 454, it is determined whether or not the brake control execution condition flag EXBK is 1. When EXBK = 1, the process proceeds to step 456. When EXBK = 0, the process proceeds to step 458. In step 456, the air conditioner is cut. In step 458, the operation of the air conditioner is restored. The same control can be performed for electric loads other than the air conditioner.

  Next, a fifth embodiment obtained by modifying the above-described fourth embodiment will be described. In the fifth embodiment, when the shortage of negative pressure is not resolved even when the operation of the air conditioner is stopped, the same control as that of the first embodiment is performed as further negative pressure recovery control. In the fifth embodiment, the brake control execution condition flag operation routine of FIG. 2 is executed, and the catalyst warm-up retardation amount calculation routine shown in FIG. 9 is executed.

The contents of steps 552, 554, 556 and 558 in FIG. 9 are the same as the contents of steps 452, 454, 456 and 458 of the air conditioner operation routine (FIG. 8) according to the fourth embodiment, respectively. In step 560 executed after the air conditioner is cut in step 556, the negative pressure PBK detected by the brake booster pressure sensor 52 is compared with the reference value P _0. When PBK> P ₀ , that is, the negative pressure is still insufficient. If it is determined that the negative pressure is restored, the routine proceeds to step 562 and thereafter. On the other hand, if PBK ≦ P ₀ , that is, if it is determined that the negative pressure has been recovered, this routine is terminated. The contents of steps 562, 564, and 566 are the same as the contents of steps 154, 156, and 158 of the catalyst warm-up retard amount calculation routine (FIG. 3) according to the first embodiment, respectively.

  Next, a sixth embodiment of the present invention will be described. In the sixth embodiment, a variable valve timing (VVT) mechanism 58 is used. FIG. 10 is a valve timing diagram in which the opening / closing timings of the intake valve and the exhaust valve are represented by crank angles. As shown in this figure, the exhaust valve is opened at a fixed valve opening timing EVO and closed at a fixed valve closing timing EVC. On the other hand, the intake valve has a constant valve opening period, but its valve opening timing IVO and valve closing timing IVC are variable, and the most retarded opening / closing timing (IVOr and IVCr in the figure) is set as a reference position. Both can be set to timings displaced by an arbitrary amount in the advance direction. The valve timing displacement amount VTD from this reference position is set as a control amount.

  In the sixth embodiment, the same routine as the brake control execution condition flag operation routine (FIG. 2) in the first embodiment is executed, and the VVT mechanism operation routine shown in FIG. 11 is executed. In general, when the intake valve timing is advanced, air is easily taken into the cylinder, and as a result, the absolute value of the intake pipe negative pressure increases. Therefore, in this sixth embodiment, the shortage of negative pressure is resolved by advancing the intake valve timing.

  That is, in the VVT mechanism operation routine of FIG. 11, first, at step 652, it is determined whether or not the intake valve timing displacement amount VTD is 0. When VTD = 0, the routine proceeds to step 654, while when VTD ≠ 0, End the routine. In step 654, it is determined whether or not the brake control execution condition flag EXBK is 1. When EXBK = 1, the process proceeds to step 656, and when EXBK = 0, the process proceeds to step 658. In step 656, the intake valve timing is advanced by a predetermined angle. In step 658, the intake valve timing is returned to the most retarded position.

  Next, a seventh embodiment obtained by modifying the above-described sixth embodiment will be described. In the seventh embodiment, when the shortage of negative pressure is not resolved even if the intake valve timing is advanced, the same control as that of the first embodiment is performed as further negative pressure recovery control. In the seventh embodiment, the brake control execution condition flag operation routine of FIG. 2 is executed, and the catalyst warm-up retardation amount calculation routine shown in FIG. 12 is executed.

The contents of steps 752, 754, 756, and 758 in FIG. 12 are the same as the contents of steps 652, 654, 656, and 658 of the VVT mechanism operation routine (FIG. 11) according to the sixth embodiment. In step 760 is performed after the advance operation of the intake valve timing in step 756, the pressure PBK detected by the brake booster pressure sensor 52 is compared with a reference value P _0, PBK> i.e. negative pressure when the P ₀ When it is determined that the pressure is still insufficient, the routine proceeds to step 762 and thereafter. On the other hand, when PBK ≦ P ₀ , that is, when it is determined that the negative pressure has been recovered, this routine is terminated. The contents of Steps 762, 764, and 766 are the same as the contents of Steps 154, 156, and 158 of the catalyst warm-up retardation amount calculation routine (FIG. 3) according to the first embodiment, respectively.

  Next, an eighth embodiment of the present invention will be described. In the eighth embodiment, the same routine as the brake control execution condition flag operation routine (FIG. 2) in the first embodiment is executed, and the transmission operation routine shown in FIG. 13 is executed. Generally, the absolute value of the negative pressure can be increased by switching the transmission to the low speed side (shifting down) to increase the rotational speed. Therefore, in the eighth embodiment, the transmission 42 is used, and the lack of negative pressure is resolved by downshifting.

  That is, in the transmission operation routine of FIG. 13, first, in step 852, it is determined whether or not the transmission is in a gear stage other than the first speed. End the routine. In step 854, it is determined whether or not the brake control execution condition flag EXBK is 1. When EXBK = 1, the process proceeds to step 856, and when EXBK = 0, the process proceeds to step 858. In step 856, downshifting is performed, and in step 858, the transmission is returned to the normal state.

  Next, a ninth embodiment obtained by modifying the above-described eighth embodiment will be described. In the eighth embodiment, when the shortage of the negative pressure is not eliminated even after the shift down, the same control as that of the first embodiment is performed as a further negative pressure recovery control. In the ninth embodiment, the brake control execution condition flag operation routine of FIG. 2 is executed, and the catalyst warm-up retardation amount calculation routine shown in FIG. 14 is executed.

The contents of steps 952, 954, 956, and 958 in FIG. 14 are the same as the contents of steps 852, 854, 856, and 858 of the transmission operation routine (FIG. 13) according to the eighth embodiment, respectively. Then, in step 960 are performed after performing the shift-down in step 856, compares the pressure PBK detected by the brake booster pressure sensor 52 with a reference value P _0, PBK> Contact lack such or negative pressure when the P ₀ When it is determined that the pressure has been reached, the routine proceeds to step 962 and after. On the other hand, when PBK ≦ P ₀ , that is, when it is determined that the negative pressure has been recovered, this routine is terminated. The contents of Steps 962, 964, and 966 are the same as the contents of Steps 152, 154, 156, and 158 of the catalyst warm-up retardation amount calculation routine (FIG. 3) according to the first embodiment, respectively.

  Next, a tenth embodiment of the present invention will be described. FIG. 15 is a flowchart showing a processing procedure of a brake control execution condition flag operation routine according to the tenth embodiment, and FIG. 16 is a flowchart showing a processing procedure of a catalyst warm-up delay amount calculation routine according to the tenth embodiment. It is. The contents of steps 1002, 1004, 1006, 1008, 1010 and 1012 in FIG. 15 are the same as the steps 102, 104, 108, 110, 112 and 114 of the brake control execution condition flag operation routine (FIG. 2) according to the first embodiment. Each content is the same. Further, the contents of steps 1052, 1056, 1058, and 1060 in FIG. 16 are the same as the contents of steps 152, 154, 156, and 158 of the catalyst warm-up delay amount calculation routine (FIG. 3) according to the first embodiment, respectively. is there.

  That is, compared with the first embodiment, the step (step 106 in FIG. 2) for determining whether or not the signal BKSW from the brake switch 36 is ON is deleted, while the step 1054 (FIG. 16) is added. Has been. In this step 1054, the brake sensor 54 detects the brake depression amount (that is, the booster operation amount), and calculates the depression speed (that is, the booster operation speed) from the temporal change of the depression amount. Then, the required negative pressure corresponding to the brake depression amount and the depression speed is calculated by referring to a map as shown in FIG. 17 stored in advance in the memory in the control device 60. Thus, in the tenth embodiment, the calculation accuracy of the required negative pressure is improved.

  Next, an eleventh embodiment of the present invention will be described. In the eleventh embodiment, the target braking force and the realizable braking force are obtained, and when the realizable braking force is lower than the target braking force, the catalyst warm-up delay amount is decreased and the idle rotation maintaining torque at that time is realized. In order to improve the braking force, the absolute value of the negative pressure is increased by reducing the throttle opening. FIG. 18 is a flowchart showing a processing procedure of a target braking force calculation and realizable braking force estimation routine according to the eleventh embodiment. FIG. 19 is a map referred to in the processing of FIG. FIG. 20 is a flowchart showing the processing procedure of the catalyst warm-up retarding amount calculation routine according to the eleventh embodiment.

In the target braking force calculation and feasible braking force estimation routine of FIG. 18, first, in step 1102, the vehicle speed SPD calculated based on the output of the vehicle speed sensor 44 is compared with the reference value S _0, and when SPD> S _0. While proceeding to step 1104, when SPD ≦ S ₀ , this routine is terminated. In step 1104, it is determined whether or not the idle ON flag EXIDL is ON. If it is ON, the process proceeds to step 1106. If it is OFF, this routine is ended.

  In step 1106, the brake depression amount is detected by the brake sensor 54, the depression speed is calculated from the temporal change of the depression amount, and is stored in the memory in the control device 60 in advance as shown in FIG. By referring to the map, the target braking force TTBKP corresponding to the brake depression amount and the depression speed is calculated. Next, at step 1108, a realizable braking force TBKP is calculated based on the negative pressure PBK detected by the brake booster pressure sensor 52. For this calculation, a map for obtaining the realizable braking force TBKP from the negative pressure PBK is stored in advance in a memory in the control device 60.

  Next, in the catalyst warm-up retarding amount calculation routine of FIG. 20, first, at step 1152, the target braking force TBKP and the realizable braking force TBKP are compared. In this case, this routine is terminated. In step 1154, the required negative pressure is calculated from the deviation between TTBKP and TBKP. For this calculation, a map for obtaining the required negative pressure from the deviation is stored in the memory in the control device 60 in advance. The contents of subsequent steps 1156, 1158, and 1160 are the same as the contents of steps 154, 156, and 158 of the catalyst warm-up retard amount calculation routine (FIG. 3) according to the first embodiment, respectively.

  Instead of the routine of FIG. 20, a catalyst warm-up retarding amount calculation routine as shown in FIG. 21 may be used. In this routine, a deviation DTBKP between the target braking force TTBKP and the realizable braking force TBKP is calculated (step 1184), and the catalyst warm-up delay amount is directly calculated from the deviation DTBKP (step 1186). For this calculation, a map for obtaining the catalyst warm-up retardation amount from the deviation DTBKP is stored in advance in the memory in the control device 60.

  Next, a twelfth embodiment of the present invention will be described. In the twelfth embodiment, the target braking force and the actual braking force are obtained, and when the actual braking force is lower than the target braking force, the catalyst warm-up delay amount is decreased, and the idle rotation maintaining torque at that time is realized. The absolute value of the negative pressure is increased and the braking force is improved by reducing the throttle opening. FIG. 22 is a flowchart showing the processing procedure of the target braking force calculation and actual braking force estimation routine according to the twelfth embodiment. FIG. 23 is a map referred to in the processing of FIG. FIG. 24 shows a map for obtaining, and a flowchart showing a processing procedure of a catalyst warm-up retardation amount calculation routine according to the twelfth embodiment.

  The contents of steps 1202, 1204, and 1206 in the target braking force calculation and actual braking force estimation routine of FIG. 22 are the same as the contents of steps 1102, 1104, and 1106 in FIG. In step 1208, the deceleration is calculated from the temporal change in the vehicle speed detected by the vehicle speed sensor 44, and by referring to a map as shown in FIG. 23 stored in the memory in the control device 60 in advance. An actual braking force TBKPN corresponding to the deceleration is calculated. Further, the catalyst warm-up retardation amount calculation routine of FIG. 24 is obtained by replacing the realizable braking force TBKP with the actual braking force TBKPN in the routine of FIG.

  Instead of the routine of FIG. 24, a catalyst warm-up retardation amount calculation routine as shown in FIG. 25 may be used. In this routine, a deviation DTBKPN between the target braking force TTBKP and the actual braking force TBKPN is calculated (step 1284), and the catalyst warm-up delay amount is directly calculated from the deviation DTBKPN (step 1286). For this calculation, a map for obtaining the catalyst warm-up retardation amount from the deviation DTBKPN is stored in advance in the memory in the control device 60.

  Next, a thirteenth embodiment of the present invention is described. This thirteenth embodiment is a modification of the eleventh embodiment described above, and step 1108 of the target braking force calculation and realizable braking force estimation routine (FIG. 18) according to the eleventh embodiment is shown in FIG. Step 1308 is changed. That is, in step 1308, the realizable braking force TBKP is calculated based on the driving torque in addition to the negative pressure PBK detected by the brake booster pressure sensor 52.

  A processing routine for calculating the driving torque is shown in the flowchart of FIG. In this routine, first, in step 1302, the engine indicated torque is calculated from the actual air amount, the ignition timing, and the air-fuel ratio (A / F). Next, at step 1304, the engine output shaft torque is calculated by subtracting the auxiliary machine loss, the pump loss, and the mechanical loss from the engine indicated torque. In the final step 1306, the drive torque is calculated from the engine output shaft torque, the torque ratio, the gear ratio, and the drive system transmission efficiency. The calculation accuracy of the realizable braking force TBKP can be improved by calculating the realizable braking force TBKP in consideration of the driving torque thus calculated.

  By the way, when the brake booster pressure sensor 52 and the brake sensor 54 are out of order, even if the above-described control is performed, a desired effect cannot be obtained, and there is a possibility of adverse effects. Therefore, it is preferable that a failure of such a sensor system can be detected. Therefore, for example, the sensor system abnormality processing routine shown in FIG. 28 is periodically executed.

  First, in step 1402, the intake pipe pressure PM indicated by the output of the intake pressure sensor 46 and the pressure PBK indicated by the output of the brake booster pressure sensor 52 are monitored for a certain period of time. In step 1404, if the PBK has an abnormal value that is difficult to assume in view of the PM value, the brake booster pressure sensor 52 is considered abnormal and the process proceeds to step 1410. On the other hand, no abnormality is recognized. If yes, go to Step 1406.

  In step 1406, a change in PBK and a change in the brake depression amount indicated by the output of the brake sensor 54 are monitored for a certain period of time. In step 1408, if it is recognized that the change in the depression amount does not correspond to the change in PBK, it is considered that the brake sensor 54 is abnormal, and the process proceeds to step 1410. On the other hand, when no abnormality is particularly recognized. Ends this routine. In step 1410, a measure for prohibiting the execution of the catalyst warm-up delay angle control is taken, and the control of the intake air amount and the ignition timing is returned to the normal control.

  The embodiment described above relates to a port injection type engine. However, in a direct combustion type lean combustion engine, lean control may be performed to improve catalyst warm-up performance. Even in such a case, the absolute value of the intake pipe negative pressure is lowered, and there is a possibility that the braking performance is lowered. Therefore, in the lean combustion engine, the negative pressure can be recovered by stopping the lean control.

1 is an overall schematic diagram of an internal combustion engine including a control device according to the present invention. It is a flowchart which shows the process sequence of the brake control execution condition flag operation routine which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 1st Embodiment. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 2nd Embodiment of this invention. (A) And (B) is a figure which shows the map for calculating | requiring a request | requirement negative pressure from brake switch ON time. It is a flowchart which shows the process sequence of the brake control execution condition flag operation routine which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of the throttle opening calculation routine which concerns on 3rd Embodiment. It is a flowchart which shows the process sequence of the air-conditioner operation routine which concerns on 4th Embodiment of this invention. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 5th Embodiment of this invention. FIG. 6 is a valve timing diagram in which opening / closing timings of an intake valve and an exhaust valve are represented by crank angles. It is a flowchart which shows the process sequence of the VVT mechanism operation routine which concerns on 6th Embodiment of this invention. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 7th Embodiment of this invention. It is a flowchart which shows the process sequence of the transmission operation routine which concerns on 8th Embodiment of this invention. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 9th Embodiment of this invention. It is a flowchart which shows the process sequence of the brake control execution condition flag operation routine which concerns on 10th Embodiment of this invention. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 10th Embodiment. It is a figure which shows the map for calculating a request | requirement negative pressure from brake depression amount and depression speed. It is a flowchart which shows the process sequence of the target braking force calculation and realizable braking force estimation routine which concern on 11th Embodiment of this invention. It is a figure which shows the map for calculating | requiring a target braking force from the brake depression amount and depression speed. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 11th Embodiment. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on the modification of 11th Embodiment. It is a flowchart which shows the process sequence of the target braking force calculation and actual braking force estimation routine which concern on 12th Embodiment of this invention. It is a figure which shows the map for calculating | requiring actual braking force from deceleration. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on 12th Embodiment. It is a flowchart which shows the process sequence of the catalyst warm-up retard amount calculation routine which concerns on the modification of 12th Embodiment. It is a flowchart which shows the process sequence of the target braking force calculation and realizable braking force estimation routine which concern on 13th Embodiment of this invention. It is a flowchart which shows the process sequence of a drive torque calculation routine. It is a flowchart which shows the process sequence of a sensor system abnormal process routine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Intake passage 14 Air cleaner 16 Throttle valve 17 Throttle motor 18 Surge tank 20 Intake manifold 22 Injector 24 Spark plug 26 Exhaust passage 28 Exhaust manifold 30 Catalytic converter 32 Brake booster 34 Brake pedal 36 Brake switch 38 Stop lamp 40 Crank angle sensor 42 Transmission
44 Vehicle speed sensor 46 Intake pressure sensor 48 Throttle opening sensor 50 Accelerator opening sensor 52 Brake booster pressure sensor 54 Brake sensor 56 Air conditioner
58 Variable Valve Timing (VVT) Mechanism 60 Controller

Claims (4)

A control device that is mounted on a vehicle including a brake booster that uses a suction negative pressure of an internal combustion engine as a boost source, and that executes retarded control of the ignition timing of the internal combustion engine when in a predetermined operating state,
Booster state monitoring means for monitoring the state of the brake booster during ignition timing retard control,
Negative pressure recovery control means for controlling a control parameter for changing the operating state of the internal combustion engine to eliminate the shortage of negative pressure when the booster state monitoring means detects a shortage of negative pressure;
And the negative pressure recovery control means temporarily stops the operation of the electric load of the internal combustion engine.   The negative pressure recovery control means performs at least one of the intake air amount or the ignition timing of the internal combustion engine as further negative pressure recovery control when the shortage of negative pressure is not resolved even by stopping the operation of the electric load. The control device for an internal combustion engine according to claim 1, wherein the control device is controlled.   The further negative pressure recovery control calculates the throttle opening degree to achieve the required negative pressure, estimates the intake air amount from the throttle opening degree, and the torque necessary to maintain the intake air amount and idle rotation. 3. The control device for an internal combustion engine according to claim 2, wherein an ignition timing retardation amount is calculated from the intake air amount to control the intake air amount and the ignition timing.   An abnormality processing means for detecting an abnormality of the sensor system and returning the control of the intake air amount and / or ignition timing to normal control when the abnormality is detected is further provided. The control device for an internal combustion engine according to any one of the preceding claims.

Images