JP2009036036A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

In an engine having an electronic throttle system for controlling the opening of a throttle valve and fixing the throttle opening to an opener opening when an electronic throttle fails, an intake pipe negative pressure is secured when the accelerator is OFF when the electronic throttle fails. To do.
A determination means for determining whether or not an electronic throttle is faulty and a determination means for determining whether or not an accelerator is OFF, and when the accelerator is OFF when the electronic throttle is faulty, the intake pipe is negative. Set the ignition timing so that the pressure increases. Specifically, the intake pipe negative pressure is increased by advancing the ignition timing with respect to the conventional control when the accelerator is OFF at the time of electronic throttle failure. By such ignition timing control, it becomes possible to secure a brake booster negative pressure even when the throttle opening is fixed to the opener opening due to an electronic throttle failure, and it is possible to ensure a braking performance when the electronic throttle fails. .
[Selection] Figure 6

Description

  The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device for an internal combustion engine provided with a brake booster that uses intake pipe negative pressure.

  An engine mounted on a vehicle is provided with an actuator (throttle motor) for driving a throttle valve provided in an intake passage so that the throttle opening can be controlled independently of the driver's accelerator pedal operation. It has been known.

  In the electronic throttle system, the throttle opening is controlled so that the optimum intake air amount (target intake air amount) is obtained according to the engine operating conditions such as the engine speed and the accelerator pedal depression amount (accelerator opening amount) of the driver. Is done. Specifically, the actual throttle opening of the throttle valve is detected using a throttle opening sensor or the like, and the actual throttle opening coincides with the throttle opening (target throttle opening) at which the target intake air amount can be obtained. So that the throttle motor is feedback controlled. In the electronic throttle system, the throttle valve is also opened during idle operation. The throttle valve opening is adjusted so that the actual idle speed matches the target idle speed, and the idle speed is feedback controlled. (ISC: Idle Speed Control).

  In such an electronic throttle system (hereinafter sometimes simply referred to as “electronic throttle”), when a throttle opening sensor, throttle valve, throttle motor or control system has failed (hereinafter referred to as “electronic throttle failure”). In addition, in order to enable the vehicle to evacuate, control is performed in which the throttle opening is fixed to the opener opening (see, for example, Patent Document 1). Thus, when the throttle valve opening is fixed at the opener opening, the engine timing is controlled by setting the ignition timing at the time of electronic throttle failure to the retard side relative to the ignition timing at the normal time. The control for setting the ignition timing to the retard side when the electronic throttle fails is hereinafter sometimes simply referred to as “conventional control”.

  As an ignition timing control for an engine mounted on a vehicle, a KCS (knock control system) that suppresses the occurrence of knocking is known. Ignition timing control by KCS determines the presence or absence of knocking based on the output signal of the knock sensor, and retards the combustion timing of the air-fuel mixture by retarding the ignition timing from the base ignition timing based on the determination result This is a method of suppressing the occurrence of knocking by keeping the maximum combustion pressure low. When it is determined that knocking has not occurred, ignition timing control is performed in which the ignition timing is gradually advanced to optimize the ignition timing.

  In such ignition timing control by KCS, every time retard angle control is executed, the retard amount of the ignition timing is learned as a KCS learning value (hereinafter, this learning control is also referred to as KCS learning control). In this KCS learning control, the retard amount of the ignition timing is learned so that the ignition timing is retarded when knocking occurs, and the ignition timing is gradually advanced when knocking does not occur. Is the amount learned.

  On the other hand, in a vehicle equipped with an engine, a brake booster is installed to obtain a strong brake braking force with a light depression force (stepping force) of the brake pedal, and the brake booster negative pressure is secured by the engine intake pipe negative pressure. It is known to do. In this brake booster, when the intake pipe negative pressure decreases (that is, when the differential pressure between the intake pipe negative pressure and the atmospheric pressure decreases), the effect of amplifying the brake braking force decreases, so that a stable brake braking force can be obtained. It is necessary to ensure a moderate intake pipe negative pressure. As techniques for ensuring intake pipe negative pressure (brake booster negative pressure), there are techniques described in Patent Documents 2 to 4 below.

  In the technique described in Patent Document 2, ignition timing retardation is prohibited until the intake pipe negative pressure can secure the brake booster negative pressure when the catalyst is warmed up at the time of engine start, and the intake pipe negative pressure is reduced to the brake booster negative pressure. By starting the ignition retard control when the engine pressure is reduced to a value that can secure the value, it is possible to achieve both the reduction of exhaust emission when starting the engine and the early securing of the brake booster negative pressure.

  In the technique described in Patent Document 3, when the shortage of the brake booster negative pressure is detected during the execution of the ignition timing retarding control for improving the catalyst warm-up property, either the intake air amount or the ignition timing is selected. By controlling this, both improvement of catalyst warm-up and securing of braking performance are realized.

In the technique described in Patent Document 4, in a control device for an internal combustion engine that performs ignition timing retardation control immediately after engine startup, the brake booster negative pressure is set to the maximum engine speed at engine startup and the brake operation after engine startup. The ignition timing retardation control is temporarily stopped or suppressed in order to recover the brake booster negative pressure based on the estimated negative pressure.
JP 10-291469 A JP 2002-349407 A JP 2001-355494 A JP 2006-170083 A

  By the way, in a vehicle equipped with an electronic throttle system, as described above, the throttle opening is fixed to the opener opening when the electronic throttle is broken, so that the intake pipe negative pressure is lowered. In other words, the opener opening that is fixed when the electronic throttle is broken is a throttle opening that can be evacuated, and is larger than the throttle opening (idle opening) that is set when the accelerator is OFF. In some cases (accelerator OFF), the intake pipe negative pressure decreases and the brake booster negative pressure becomes lower than the required negative pressure. If the brake booster negative pressure is reduced in this way, there is a concern that the brake will become poorer even though the driver is stepping on the brake pedal.

  Here, when the electronic throttle is broken, that is, when the throttle opening is fixed, it is necessary to increase the engine speed in order to secure the intake pipe negative pressure. By reducing the external load or downshifting while the vehicle is running, the engine speed is increased to recover the intake pipe negative pressure when the electronic throttle fails. However, even if such measures are taken, there is a limit to recovering the intake pipe negative pressure.

  Further, if the throttle valve is closed when the electronic throttle fails, the intake pipe negative pressure can be secured. However, if the throttle valve is closed, the running performance when the electronic throttle fails is deteriorated. Therefore, it is difficult to achieve both the intake pipe negative pressure securing and the evacuation traveling when the electronic throttle fails.

  In addition, Patent Documents 2 to 4 only describe a technique for securing a brake booster negative pressure at the time of starting the engine, and no mention is made regarding control at the time of electronic throttle failure. Even when the throttle opening is fixed to the opener opening, no measures are taken into account. Therefore, the techniques described in Patent Documents 2 to 4 cannot solve the above-described problem of the intake pipe negative pressure drop when the electronic throttle fails.

  The present invention has been made in view of such circumstances, and is provided with an electronic throttle system that includes an electronic throttle system that controls the opening of a throttle valve and fixes the throttle opening to an opener opening when an electronic throttle fails. It is an object of the present invention to provide a fuel injection control device capable of ensuring intake pipe negative pressure when the accelerator is OFF at the time of failure.

-Solving principle-
The solution principle of the present invention taken to achieve the above object is that when the throttle opening is fixed to the opener opening due to an electronic throttle failure, a negative pressure (intake pipe) larger than that in the conventional control is set in the intake passage. The ignition timing of the internal combustion engine is set so that the negative pressure is generated. By such ignition timing control, it is possible to suppress the decrease in the brake booster negative pressure when the accelerator is OFF when the electronic throttle is broken, and it is possible to ensure the braking performance when the electronic throttle is broken.

-Solution-
Specifically, the present invention includes a throttle valve disposed in the intake passage, an accelerator opening detecting means for detecting an accelerator opening, a throttle control means for controlling the throttle opening of the throttle valve, and the throttle control means. An ignition timing control for an internal combustion engine that fixes the throttle opening to an opener opening when a failure of the throttle control means is determined by the failure detection means. Assume equipment. In such an ignition timing control device for an internal combustion engine, when the throttle control means is in failure (hereinafter referred to as electronic throttle failure) and the accelerator is OFF, the intake pipe negative pressure (absolute value) of the internal combustion engine. The ignition timing is set so as to be large.

  The present invention is particularly suitable for ignition timing control of an internal combustion engine provided with a brake booster that uses the intake pipe negative pressure downstream of a throttle valve disposed in the intake passage.

  According to the present invention, it is possible to ensure the intake pipe negative pressure when the accelerator is OFF, even if the throttle opening is fixed to the opener opening due to an electronic throttle failure. This point will be described.

  First, in the conventional control described above, the ignition timing is set (corrected) by calculating the retard amount from the normal ignition timing according to the engine operating state when the electronic throttle is broken. From the timing set value, it is possible to change the ignition timing to approach the normal ignition timing, that is, to advance the ignition timing by the retard amount. Here, if the ignition timing at the time of failure of the electronic throttle is advanced with respect to the ignition timing of the conventional control, the intake pipe negative pressure can be increased as shown in FIG. The intake pipe negative pressure becomes maximum. Focusing on this point, in the present invention, when the accelerator is OFF (deceleration) at the time of electronic throttle failure, the intake pipe negative pressure is prioritized and the ignition timing is advanced over the ignition timing of the conventional control. Then, by increasing the intake pipe negative pressure, the intake pipe negative pressure is secured when the electronic throttle is malfunctioning or the accelerator is off.

  Thus, according to the present invention, the intake pipe negative pressure can be ensured even when the throttle opening is fixed to the opener opening due to an electronic throttle failure. As a result, the brake booster negative pressure is not deficient when the electronic throttle is broken or the accelerator is off, and the brake performance when the electronic throttle is broken can be secured.

  Specific examples of the present invention include the following.

  First, an ignition timing can be set so that the intake pipe negative pressure of the internal combustion engine is maximized based on the operating state of the internal combustion engine when the accelerator is OFF due to a malfunction of the electronic throttle. In this case, for example, the ignition timing at which the intake pipe negative pressure is maximized when the accelerator is OFF due to an electronic throttle failure is determined and mapped for each engine operating condition. The ignition timing may be calculated and set by referring to a map based on the operating state of the internal combustion engine at that time. Examples of the operating conditions of the internal combustion engine when calculating such ignition timing include the engine speed and the load.

  As another specific configuration, when KCS learning control is set that determines whether or not knocking has occurred in the internal combustion engine and learns, as a KCS learning value, an ignition timing that suppresses the occurrence of knocking based on the determination result Further, there can be mentioned a configuration in which the KCS learning value is changed to the advance side so that the intake pipe negative pressure of the internal combustion engine becomes large when the accelerator is OFF at the time of electronic throttle failure. In this case, for example, by a simple process of initializing the KCS learning value (KCS learning value = 0), the ignition timing at the time of electronic throttle failure / accelerator OFF can be set to the advance side, and the intake pipe negative The pressure can be increased.

  In addition, when KCS learning control is set, when the accelerator is turned off at the time of electronic throttle failure, a preset learning value at the time of failure (ignition timing setting value for increasing intake pipe negative pressure) is set as KCS learning. It may be set to be a value.

  Also, when the failure timing fire timing control (the above-described conventional control) is set so that the ignition timing at the time of electronic throttle failure is retarded from the normal ignition timing, when the accelerator is OFF at the time of electronic throttle failure In addition, a configuration in which the failure-time ignition timing is corrected using the failure advance angle so that the intake pipe negative pressure becomes large can be mentioned. In this case, the intake pipe negative pressure at the time of electronic throttle failure / accelerator OFF is increased by a simple process of correcting the ignition timing of the conventional control (base ignition timing at the time of electronic throttle failure) using the advance angle amount at the time of failure. can do.

  Furthermore, as another specific configuration of the present invention, there can be mentioned a configuration in which the ignition timing is set so that the engine torque of the internal combustion engine becomes large when the accelerator is ON at the time of electronic throttle failure. This configuration will be described.

  First, as described above, in the conventional control, the ignition timing is set (corrected) by calculating the retard amount from the normal ignition timing according to the engine operating state when the electronic throttle is broken. From the ignition timing set value of the control, it is possible to change the ignition timing to approach the normal ignition timing, that is, advance the ignition timing by the retard amount. Here, if the ignition timing at the time of electronic throttle failure is advanced with respect to the ignition timing of the conventional control, the engine torque of the internal combustion engine can be increased as shown in FIG. The engine torque becomes maximum at the time. Paying attention to such points, in the present invention, when the accelerator is on (running) at the time of electronic throttle failure, traveling performance is ensured by setting an ignition timing that prioritizes increasing the engine torque. .

  According to the present invention, the ignition timing is set so that the intake pipe negative pressure of the internal combustion engine increases when the accelerator is OFF when the electronic throttle is broken. The intake pipe negative pressure can be secured even if it is fixed to. As a result, the brake booster negative pressure will not be insufficient when the electronic throttle is broken or the accelerator is OFF (deceleration), and the brake performance when the electronic throttle is broken can be secured.

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

  First, an engine (internal combustion engine) to which the present invention is applied will be described.

-Engine-
FIG. 1 is a diagram showing a schematic configuration showing an example of an engine 1 to which the present invention is applied. FIG. 1 shows only the configuration of one cylinder of the engine 1.

  The engine 1 in this example is, for example, a four-cylinder gasoline engine, and includes a piston 1b that forms a combustion chamber 1a and a crankshaft 15 that is an output shaft. The piston 1b is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1b is converted into rotation of the crankshaft 15 by the connecting rod 16.

  A signal rotor 17 having a plurality of protrusions (teeth) 17 a on the outer peripheral surface is attached to the crankshaft 15. A crank position sensor (engine speed sensor) 25 is disposed near the side of the signal rotor 17. The crank position sensor 25 is, for example, an electromagnetic pickup, and generates a pulsed signal (output pulse) corresponding to the protrusion 17a of the signal rotor 17 when the crankshaft 15 rotates.

  A water temperature sensor 21 and a knock sensor 22 that detect the coolant temperature of the engine 1 are disposed in the cylinder block 1 c of the engine 1. The knock sensor 22 is a sensor that detects engine vibration transmitted to the cylinder block 1 c of the engine 1. The knock sensor 22 used in this example is a flat sensor (non-resonant knock sensor), for example, and has a substantially flat output characteristic over a wide frequency range of engine vibration.

  A spark plug 3 is disposed in the combustion chamber 1 a of the engine 1. The ignition timing of the spark plug 3 is adjusted by the igniter 4. The igniter 4 is controlled by an ECU (Electronic Control Unit) 200.

  An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 a of the engine 1. An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1a. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1a are communicated or blocked. Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1a. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1a are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft and the exhaust camshaft to which the rotation of the crankshaft 15 is transmitted.

  In the intake passage 11, an air cleaner 7, a hot-wire air flow meter 23 that detects the intake air amount, an intake air temperature sensor 24 (built in the air flow meter 23), and an electronically controlled throttle that adjusts the intake air amount of the engine 1. A valve 5 is arranged. The throttle valve 5 is driven by a throttle motor 6. The opening degree of the throttle valve 5 is detected by a throttle opening degree sensor 26.

  A brake booster 101 is connected to the intake passage 11 of the engine 1 via a negative pressure introduction path 103. The negative pressure introduction passage 103 communicates with a surge tank 11 a provided on the downstream side of the throttle valve 5 in the intake passage 11. The brake booster 101 is operated by intake pipe negative pressure, and assists the depressing operation force (brake force) of the brake pedal 102. The assist force generated by the brake booster 101 is supplied to the wheel cylinder via the master cylinder and becomes a braking force that stops the rotation of the wheel.

A three-way catalyst 8 is disposed in the exhaust passage 12 of the engine 1. A front O ₂ sensor (main O ₂ sensor) 28 is disposed in the exhaust passage 12 upstream of the three-way catalyst 8. The front O ₂ sensor 28 is a sensor that exhibits linear characteristics with respect to the air-fuel ratio. A rear O ₂ sensor (sub O ₂ sensor) 29 is disposed in the exhaust passage 12 on the downstream side of the three-way catalyst 8. The rear O ₂ sensor 29 generates an electromotive force according to the oxygen concentration in the exhaust gas. When the output is higher than a voltage (comparison voltage) corresponding to the theoretical air-fuel ratio, the rear O ₂ sensor 29 determines that the output is rich. When the output is lower than the comparison voltage, it is determined as lean.

  A fuel injection injector 2 is disposed in the intake passage 11. Fuel of a predetermined pressure is supplied from the fuel tank to the injector 2 by a fuel pump, and the fuel is injected into the intake passage 11. This injected fuel is mixed with intake air to form an air-fuel mixture and introduced into the combustion chamber 1a of the engine 1. The air-fuel mixture (fuel + air) introduced into the combustion chamber 1a is ignited by the spark plug 3 and burns and explodes. The piston 1b reciprocates due to combustion / explosion of the air-fuel mixture in the combustion chamber 1a, and the crankshaft 15 rotates. The operation state of the engine 1 described above is controlled by the ECU 200.

-ECU-
As shown in FIG. 2, the ECU 200 includes a CPU 201, a ROM 202, a RAM 203, a backup RAM 204, and the like.

  The ROM 202 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 201 executes various arithmetic processes based on various control programs and maps stored in the ROM 202. The RAM 203 is a memory that temporarily stores calculation results of the CPU 201, data input from each sensor, and the backup RAM 204 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.

  The CPU 201, the ROM 202, the RAM 203, and the backup RAM 204 are connected to each other via the bus 207, and are connected to the input interface 205 and the output interface 206.

The input interface 205 includes a water temperature sensor 21, a knock sensor 22, an air flow meter 23, an intake air temperature sensor 24, a crank position sensor 25, a throttle opening sensor 26, and a detection signal (accelerator ON / OFF ON / OFF signal). An accelerator opening sensor 27, a front O ₂ sensor 28, a rear O ₂ sensor 29, and the like are also connected.

  The output interface 206 is connected to the injector 2, the igniter 4 of the spark plug 3, the throttle motor 6 of the throttle valve 5, and the like.

  The ignition plug 3, the igniter 4, the air flow meter 23, the crank position sensor 25, the throttle opening sensor 26, the accelerator opening sensor 27, the ECU 200, and the like realize an ignition timing control device.

  The ECU 200 executes various controls of the engine 1 based on the detection signals of the various sensors described above.

For example, the main air-fuel ratio feedback control is executed based on the output of the front O ₂ sensor 28 disposed in the exhaust passage 12 (upstream of the three-way catalyst 8) of the engine 1. Further, the sub air-fuel ratio feedback control is executed based on the output of the rear O ₂ sensor 29 arranged in the exhaust passage 12 (downstream of the three-way catalyst 8) of the engine 1.

In the main air-fuel ratio feedback control, the amount of fuel injected from the injector 2 to the intake passage 11 is controlled so that the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 8 matches the control target air-fuel ratio. Further, in the sub air-fuel ratio feedback control, more specifically, the rear disposed on the downstream side of the three-way catalyst 8 so that the air-fuel ratio of the exhaust gas flowing out downstream of the three-way catalyst 8 becomes the stoichiometric air-fuel ratio. The content of the main air-fuel ratio feedback control is corrected so that the output of the O ₂ sensor 29 becomes stoichiometric. By executing these air-fuel ratio feedback control, the air-fuel ratio on the downstream side of the three-way catalyst 8 can be accurately maintained at a value close to the stoichiometric air-fuel ratio, and excellent emission characteristics can be realized.

  Further, the ECU 200 executes ignition timing control of the engine 1 and electronic throttle failure control including the following KCS learning control.

-KCS learning control-
The KCS learning control is a control that suppresses the occurrence of knocking of the engine 1, and determines whether or not knocking has occurred based on the output signal of the knock sensor 22, and delays the ignition timing from the base ignition timing based on the determination result. In addition, the ignition timing is retarded (KCS learning value).

  Specifically, based on the engine speed obtained from the output signal of the crank position sensor 25 and the intake air amount obtained from the output signal of the air flow meter 23, the base ignition timing is calculated with reference to a preset map. At the same time, the peak value of the knock signal from knock sensor 22 is compared with the knock determination level to determine whether knock has occurred or not. When it is determined that knocking has occurred, the ignition timing is retarded from the base ignition timing, thereby reducing the combustion speed of the air-fuel mixture and keeping the maximum combustion pressure low, thereby suppressing the occurrence of knocking. Further, the retard amount of the ignition timing is learned as a KCS learning value and stored in the RAM 203 or the backup RAM 204. In this KCS learning control, the retard amount is learned so that the ignition timing is retarded when knocking occurs, and the ignition timing is gradually advanced when knocking does not occur. The amount to be learned.

  Here, the base ignition timing is the most advanced ignition timing that does not cause knocking under standard environmental conditions based on the operating state of the engine 1 such as the engine speed and load. The load of the engine 1 is a required load (requested torque) obtained from an accelerator opening, an air conditioner load, an electric load, and the like. For example, based on an intake air amount obtained from an output signal of the air flow meter 23. Calculate with reference to the map. The load of the engine 1 may be calculated based on the intake air amount and the engine speed.

-Electronic throttle failure control-
In this example, when the throttle opening sensor 26, the throttle valve 5, the throttle motor 6 or the control system or the like fails (electronic throttle failure), the throttle is secured in order to ensure vehicle forward (retreat travel) and engine stall prevention. The control of the opening degree is prohibited, and the opening degree of the throttle valve 5 is fixed to the opener opening degree by a mechanical device such as a spring.

  As a method for detecting an electronic throttle failure, for example, when the electronic throttle is normal, the non-linear throttle opening obtained from the accelerator opening and the actual throttle opening move with a certain relationship. When the difference between the nonlinear throttle opening and the actual throttle opening is larger than a predetermined value, a method is adopted in which it is determined that the electronic throttle has failed. The accelerator opening used for the electronic throttle failure determination is calculated from the output signal of the accelerator opening sensor 27, and the actual throttle opening is calculated from the output signal of the throttle opening sensor 26. In addition, as a method for determining an electronic throttle failure, a method is adopted in which the energization state of the throttle opening sensor 26 and the throttle motor 6 is monitored and an electronic throttle failure is determined when disconnection of these devices is detected. Also good.

-Ignition timing calculation process-
Next, the ignition timing calculation process executed by the ECU 200 will be described.

  First, an ignition timing calculation map used in the ignition timing calculation process of this example will be described with reference to FIGS.

  The ignition timing calculation map shown in FIG. 4 is a map used when the electronic throttle is malfunctioning and the accelerator is OFF, and is a map for calculating the ignition timing by giving priority to the intake pipe negative pressure of the engine 1. Specifically, using the engine speed and load as parameters, the ignition timing (see FIG. 6) at which the intake pipe negative pressure is maximized when the electronic throttle is faulty or the accelerator is OFF is obtained in advance through experiments, calculations, etc. Is a three-dimensional map. The ignition timing calculation map of FIG. 4 is stored in the ROM 202 of the ECU 200.

  In the ignition timing calculation map of FIG. 4, the ignition timing is set to an advance value as the engine speed increases, and the ignition timing becomes a retard value as the load increases. Is set to Note that the ignition timing in the ignition timing calculation map of FIG. 4 is set to a value that is more advanced than the ignition timing of the conventional control if the operating conditions (engine speed / load) at the time of electronic throttle failure are the same. It is set (see FIG. 6).

  Next, a map used when the electronic throttle is broken and the accelerator is ON will be described. First, it is desirable to increase the engine torque in order to ensure running performance when the electronic throttle is broken or the accelerator is on (running). Considering this point, in this example, priority is given to the engine torque, and the ignition timing (see FIG. 7) is set so that the maximum engine torque can be obtained in a situation where the throttle opening is fixed at the opener opening. This map is used (FIG. 5).

  The ignition timing calculation map shown in FIG. 5 uses an engine speed and a load as parameters, and previously obtains an ignition timing (see FIG. 7) at which the engine torque becomes maximum when the electronic throttle is broken or when the accelerator is on by experiments and calculations. This is a three-dimensional map obtained by mapping the result. This ignition timing calculation map is stored in the ROM 202 of the ECU 200.

  In the ignition timing calculation map of FIG. 5, the ignition timing is set to an advance value as the engine speed increases, and the ignition timing becomes a retard value as the load increases. Is set to Note that the ignition timing in the ignition timing calculation map of FIG. 5 is set to a value that is more advanced than the ignition timing of the conventional control if the operating conditions (engine speed / load) at the time of failure of the electronic throttle are the same. It is set (see FIG. 7).

  Next, a specific example of the ignition timing calculation process of this example will be described with reference to the flowchart shown in FIG. The control routine of FIG. 3 is repeatedly executed in the ECU 200 at predetermined time intervals.

  In step ST1, it is determined whether or not the electronic throttle has failed. If the determination result is negative (when the electronic throttle is normal), the routine is temporarily exited after calculating the normal ignition timing in step ST5. If the determination result in step ST1 is affirmative (when the electronic throttle is malfunctioning), the process proceeds to step ST2, and it is determined whether or not the accelerator is OFF based on the output signal of the accelerator opening sensor 27.

  If the determination result in step ST2 is affirmative, the ignition timing is calculated giving priority to the intake pipe negative pressure of the engine 1 because it is determined that the electronic throttle is decelerating. Specifically, in step ST3, the engine speed obtained from the crank position sensor 25 and the load calculated based on the intake air amount obtained from the output signal of the air flow meter 23 are used. Based on the above, the ignition timing calculation map shown in FIG. 4 is referred to, so that the ignition timing at which the intake pipe negative pressure of the engine 1 is maximized (ignition timing at the time of electronic throttle failure / accelerator OFF) is calculated. After this, this routine is temporarily exited.

  On the other hand, if the determination result in step ST2 is negative, it is determined that the vehicle is running continuously when the electronic throttle has failed, and the ignition timing is calculated giving priority to the engine torque. Specifically, in step ST4, the engine speed obtained from the crank position sensor 25 and the load calculated based on the intake air amount obtained from the output signal of the air flow meter 23 are used. Based on the above, the ignition timing calculation map shown in FIG. 5 is referred to, and the ignition timing that maximizes the engine torque (ignition timing at the time of electronic throttle failure / accelerator ON) is calculated. After this, this routine is temporarily exited.

  As described above, according to the control of this example, when the accelerator is OFF (deceleration) at the time of electronic throttle failure, the ignition timing is calculated and set so that the intake pipe negative pressure of the engine 1 becomes maximum. Even if the throttle opening is fixed at the opener opening when the electronic throttle fails, it is possible to secure the brake booster negative pressure when the accelerator is OFF, and the braking performance when the electronic throttle fails can be ensured.

  Also, when the accelerator is on (running continuation) at the time of electronic throttle failure, the ignition timing is calculated and set so that the engine torque becomes maximum, so the throttle opening is fixed at the opener opening at the time of electronic throttle failure. Under the circumstances, the engine torque can be maximized, which makes it possible to ensure the running performance when the electronic throttle fails.

  Here, in the above example, when the accelerator is ON (running continuation) at the time of electronic throttle failure, the ignition timing is set so that the engine torque becomes maximum regardless of the accelerator opening, but this is not limitative. Instead, the magnitude of the engine torque may be set in accordance with the magnitude of the accelerator opening (the amount of depression of the accelerator pedal by the driver) at the time of electronic throttle failure.

  For example, the accelerator pedal depression amount at the time of electronic throttle failure is divided into three steps: depression amount [large], depression amount [medium], and depression amount [small], and the engine torque at that depression amount [large] is shown in FIG. The ignition timing is set so that the engine torques when the maximum amount shown in FIG. 8, the depression amount [medium], and the depression amount [small] are respectively [medium] and [small] shown in FIG. May be. When such ignition timing control is performed, the engine torque can be set in a stepwise manner in accordance with the driver's accelerator pedal operation, so that drivability at the time of electronic throttle failure can be improved.

-Other examples of ignition timing calculation processing-
Next, another example of the ignition timing calculation process will be described.

  (1) An example of ignition timing calculation processing when KCS learning control is being executed will be described.

  First, when the KCS learning value is on the retard side before the electronic throttle failure, when the accelerator is OFF at the time of electronic throttle failure (when both steps ST1 and ST2 in the flowchart of FIG. 3 are affirmative) A calculation process of initializing the KCS learning value (KCS learning value = 0) and setting the initialized ignition timing as the ignition timing at the time of electronic throttle failure can be given. By calculating the ignition timing by initializing the KCS learning value in this way, the ignition timing can be set to the advance side when the electronic throttle is broken or the accelerator is OFF, and the intake pipe negative pressure of the engine 1 is increased. be able to. As a result, even if the throttle opening is fixed at the opener opening when the electronic throttle fails, it is possible to ensure the negative pressure of the brake booster when the accelerator is OFF, and it is possible to ensure the braking performance when the electronic throttle fails.

  In addition, when KCS learning control is executed, when the accelerator is turned off when the electronic throttle is broken, a preset learning value at the time of failure (ignition timing setting value for increasing intake pipe negative pressure) is KCS learned. You may perform the process of setting it as a value.

  (2) When failure time ignition timing control (the above-described conventional control) is set so that the ignition timing at the time of electronic throttle failure is retarded from the normal ignition timing, the accelerator is OFF at the time of electronic throttle failure. Sometimes (when both steps ST1 and ST2 in the flowchart of FIG. 3 are affirmative), the ignition timing of the conventional control (base ignition timing at the time of electronic throttle failure) is set using a preset advance amount at failure (fixed value). ) Is corrected. When such correction is performed, the ignition timing at the time of electronic throttle failure can be set to the advance side with respect to the ignition timing of the conventional control, as shown in FIG. It becomes possible to enlarge. As a result, even if the throttle opening is fixed at the opener opening when the electronic throttle fails, it is possible to ensure the brake booster negative pressure when the accelerator is OFF, and the braking performance when the electronic throttle fails.

-Other embodiments-
In the above example, the present invention is applied to the ignition timing control of the port injection type gasoline engine. However, the present invention is not limited to this, but is also applied to the ignition timing control of the in-cylinder direct injection type gasoline engine. Is possible. In addition to the in-line multi-cylinder gasoline engine, the present invention can be applied to ignition timing control of a V-type multi-cylinder gasoline engine.

It is a schematic block diagram which shows an example of the engine (internal combustion engine) to which this invention is applied. It is a block diagram which shows the structure of control systems, such as ECU. It is a flowchart which shows an example of the control routine of an ignition timing calculation process. It is a figure which shows the ignition timing calculation map used at the time of an electronic throttle failure and accelerator OFF. It is a figure which shows the ignition timing calculation map used at the time of an electronic throttle failure and accelerator ON. It is a graph which shows the relationship between the ignition timing at the time of electronic throttle failure and accelerator OFF, and intake pipe negative pressure. It is a graph which shows the relationship between the ignition timing at the time of electronic throttle failure, and accelerator ON, and torque. It is explanatory drawing of the torque set at the time of an electronic throttle failure and an accelerator ON.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 3 Spark plug 4 Igniter 5 Throttle valve 6 Throttle motor 11 Intake passage 22 Knock sensor 23 Air flow meter 25 Crank position sensor 26 Throttle opening sensor 27 Accelerator opening sensor 101 Brake booster 102 Brake pedal 103 Negative pressure introduction path 200 ECU

Claims (7)

A throttle valve disposed in the intake passage; an accelerator opening detecting means for detecting an accelerator opening; a throttle control means for controlling the throttle opening of the throttle valve; and whether or not the throttle control means is out of order. An ignition timing control device for an internal combustion engine that fixes a throttle opening to an opener opening when a failure of the throttle control means is determined by the failure detection means.
An ignition timing control device for an internal combustion engine, wherein an ignition timing is set so that an intake pipe negative pressure of the internal combustion engine becomes large when the throttle control means is in failure and the accelerator is OFF. In the internal combustion engine ignition timing control device according to claim 1,
An internal combustion engine that sets an ignition timing so that an intake pipe negative pressure of the internal combustion engine becomes maximum based on an operating state of the internal combustion engine when the throttle control means is in failure and the accelerator is OFF. Engine ignition timing control device. The internal combustion engine ignition timing control device according to claim 1 or 2,
An ignition timing control device for an internal combustion engine, wherein an ignition timing set when the throttle control means is in failure and the accelerator is OFF is calculated based on the engine speed and load of the internal combustion engine. In the internal combustion engine ignition timing control device according to claim 1,
When the KCS learning control for determining whether or not knocking of the internal combustion engine has occurred and learning the ignition timing for suppressing the occurrence of knocking as a KCS learning value based on the determination result is set, the throttle control means fails. An ignition timing control device for an internal combustion engine, wherein the KCS learning value is changed to an advance side so that the intake pipe negative pressure of the internal combustion engine increases when the accelerator is OFF at the time. In the internal combustion engine ignition timing control device according to claim 1,
When the failure timing ignition timing control is set so that the ignition timing at the time of failure of the throttle control means is retarded from the normal ignition timing, when the throttle control means is at failure and the accelerator is OFF, the intake air An ignition timing control device for an internal combustion engine, wherein the ignition timing at the time of failure is corrected using the advance amount at the time of failure so that the pipe negative pressure becomes large. The control device for an internal combustion engine according to any one of claims 1 to 5,
An ignition timing control device for an internal combustion engine, wherein the ignition timing is set so that the engine torque of the internal combustion engine increases when the throttle control means is in failure and the accelerator is ON. The control apparatus for an internal combustion engine according to any one of claims 1 to 6,
An ignition timing control device for an internal combustion engine, comprising a brake booster that uses an intake pipe negative pressure downstream of a throttle valve disposed in the intake passage.

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