JP2007255300A - Idle stabilization controlling device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize an idle state got unstable in an engine. <P>SOLUTION: When rotation speed of the engine varies periodically and largely and an idle instability detecting section 41 detects idle instability, an instability cause determining section 42 determines an instability cause from whether the instability of the idle state varies in a direction of improvement or worse when changing generated torque of the engine, and a cause countermeasure section 43 corrects the instability cause in a direction that the idle instability is improved. The instability caused by unsuitableness of a correction amount for idle stabilization can be thus inhibited in idle stabilization control and idle stabilization can be made even to a plurality of idle instability causes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine idling stabilization control apparatus, and more particularly to an engine idling stabilization control apparatus that prevents the idling speed from becoming unstable when the vehicle is stopped and the engine is in an idling state.

  When the engine is in an idling state (idling state) where the accelerator pedal is not depressed, generally, the engine speed is controlled by controlling the intake air amount by a throttle valve, ISCV (idle speed control valve), or the like. Control is performed so as to achieve a target rotational speed corresponding to the state of the vehicle at the time. At this time, if the electrical load of the battery increases, for example, by turning on the headlight, control is performed to increase the amount of power generated by the alternator to compensate for this, but the power generated by the alternator is a load for the engine. Therefore, the engine speed falls below the target speed, and the idle state becomes unstable. Therefore, by changing the opening of the ISCV according to the engine speed and the power generation request value for the alternator, and generating the torque corresponding to the increase in the engine load corresponding to the power generation increase amount of the alternator, the engine Recovery of the drop in the rotational speed to the target rotational speed is performed (for example, refer to Patent Document 1).

  In addition, the engine speed in the idling state is preferably as low as possible from the viewpoint of fuel consumption, but the torque generated when the engine speed during idling is reduced is small, so the fluctuation of the engine speed with respect to the load fluctuation is large, So-called hunting is likely to occur and the risk of engine stall increases. Therefore, it is also known that the ignition timing of each cylinder is changed in accordance with the cylinder output during idling to suppress fluctuations in the engine speed and stabilize the idling state (see, for example, Patent Document 2). ).

In this way, the required torque of the engine in the idle state varies depending on the load of auxiliary equipment such as an alternator, so the intake air amount and ignition timing necessary to generate torque corresponding to the change are expected. By obtaining the correction amount and reflecting the correction amount in the control of the intake air amount and the ignition timing, the idling state is stabilized.
Japanese Patent No. 2635483 JP 2000-240545 A

  However, the idling state becomes unstable due to hunting, not only the fluctuation of the auxiliary load, but also the intake air amount and the ignition timing that are corrected to generate the torque corresponding to the fluctuation load. As a result, the correction of the intake air amount and the ignition timing is actually irrelevant to the fluctuation of the engine speed, or the intention to converge the fluctuation is to promote the fluctuation because the correction amount becomes excessive. There was a problem that sometimes. Also, when the idle state becomes unstable at all times, even if the vehicle is brought to a dealer or the like, there is no reference information for inspection and adjustment, so it takes a lot of time to investigate the cause of instability. It was.

  The present invention has been made in view of the above points, and provides an engine idling stabilization control device that can reliably stabilize an idling state even if the cause of idling instability is complicatedly affected. The purpose is to provide.

  In the present invention, in order to solve the above problems, idle instability detection means for detecting idling instability by monitoring fluctuations in idling speed during idling based on a signal representing engine speed, An instability cause determining means for determining the cause of instability according to whether or not the instability of the idle state changes by changing the torque generated by the engine in the idle state when the instability of the idle state is detected by the idle instability detection means; And a cause countermeasure means for correcting the unstable cause determined by the unstable cause determination means in a direction in which the instability of the idle state is improved. A control device is provided.

  According to such an engine idling stabilization control device, when the engine speed fluctuates periodically and hunts, the instability of the idling state is improved or worsened by changing the torque generated by the engine. The cause of instability is determined based on whether or not the direction has changed, and the instability is corrected in a direction that improves instability in the idle state. Thereby, it is possible to suppress instability due to an inappropriate correction amount for idling stabilization during idling stabilization control, and it is possible to achieve idling stabilization even for a plurality of idling instability causes. .

  The engine idling stabilization control apparatus according to the present invention does not correct for specific fluctuation factors such as the intake air amount and the ignition timing but stabilizes idling, when idling is unstable. If the engine control torque is changed, the idle control is temporarily changed, and if the fluctuation of the idle speed changes, it is determined that the idle is unstable, and the idle state is detected for the unstable cause. Since the correction is made in such a direction as to improve the instability, there is an advantage that a plurality of idle instability causes can be dealt with. In addition, by storing information on corrections that are performed in a direction that improves the instability of the idle state with respect to instability causes, it is reflected in the next idle control, or in the case of inspection at a dealer or the like. It can be used as a reference when adjusting the control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing the configuration around the engine of the present embodiment.
An intake pipe 2 is connected to the upstream side of the intake and exhaust system of the engine 1 of the vehicle, and an exhaust pipe 3 is connected to the downstream side. An air cleaner 4 is provided at the upstream end portion of the intake pipe 2, and an intake manifold 5 that divides the intake passage for each cylinder is provided at the downstream end portion. The air introduced into the intake pipe 2 via the air cleaner 4 is sucked into each cylinder through the intake manifold 5.

  A surge tank 6 is provided at an intermediate portion of the intake pipe 2, and a bypass passage 8 is formed so as to bypass the throttle valve 7 disposed on the upstream side thereof. A linear solenoid type ISCV 9 that adjusts the flow rate of air to be bypassed is disposed in the bypass passage 8. The ISCV 9 has a valve mechanism that opens and closes the bypass passage 8 and an ISC control solenoid that drives the valve mechanism, and is adjusted to a predetermined valve opening degree by controlling the duty ratio of the supplied current. . During idling, the engine speed is controlled by adjusting the intake air amount by controlling the opening of the ISCV 9.

  Intake manifolds 5 are each provided with an intake port provided for each cylinder in intake manifold 5. The injector 10 is supplied with fuel that has been pumped from a fuel tank (not shown) and pressure-regulated, and is opened by energization control to inject fuel into the intake port. The fuel injected at this time is mixed with intake air introduced from the upstream side to become an air-fuel mixture, and is supplied to the combustion chamber 12 of each cylinder via the intake valve 11.

  A spark plug 13 is disposed in the combustion chamber 12 of each cylinder. The spark plug 13 is applied with a high voltage generated by an ignition coil integrated igniter 14 to generate a spark for ignition. By this ignition, the air-fuel mixture in the combustion chamber 12 is combusted, and a rotational driving force is applied to the crankshaft 16 through the piston 15.

  An exhaust manifold 17 that joins exhaust passages for each cylinder and connects to the exhaust pipe 3 is provided at the upstream end of the exhaust pipe 3. Further, a catalytic converter (not shown) for purifying exhaust gas is disposed inside the exhaust pipe 3. This catalytic converter contains a three-way catalyst that simultaneously promotes oxidation of unburned components in exhaust gas and reduction of nitrogen oxides. Exhaust gas discharged from the combustion chamber 12 through the exhaust valve 18 is led to the exhaust pipe 3 through the exhaust manifold 17 and purified by a catalytic converter (not shown).

  An air flow meter 19 integrated with an intake air temperature sensor is provided at the most upstream portion of the intake pipe 2 so that the intake air amount and the intake air temperature can be detected. A throttle opening sensor 20 that detects the opening of the throttle valve 7 is provided in the vicinity of the throttle valve 7 of the intake pipe 2. Further, a crank angle sensor 21 that generates a crank angle signal at every predetermined crank angle accompanying the rotation of the crankshaft 16 is disposed in the vicinity of the crankshaft 16 in order to calculate the engine speed.

  An air conditioner 22 and an alternator 23 are connected to the crankshaft 16 of the engine 1 via a predetermined pulley. The air conditioner 22 includes a compressor (not shown) that is rotationally driven by the crankshaft 16, a control unit that controls the refrigerant discharge capacity of the compressor to a desired value regardless of the rotational speed of the engine 1, a condenser, an expansion valve, an evaporator, It consists of a heater core and adjusts the air temperature in the passenger compartment. The alternator 23 includes a rotor, a stator, a rectifier, and the like (not shown), and rotates with the rotation of the engine 1 to generate an AC voltage. The electric power generated by the alternator 23 is supplied to electrical equipment (not shown) mounted on the vehicle, and when surplus power is generated, it is supplied to a battery (not shown) and charged.

  Further, various controls of the engine 1 including intake air amount control, fuel injection control, ignition timing control, idle speed control, power generation control of the alternator 23, and the like are performed by an electronic control device (hereinafter referred to as an ECU) that is configured by a microcomputer. : Electronic Control Unit). In the present embodiment, a part of the ECU 30 constitutes an engine idle stabilization control device.

FIG. 2 is a block diagram illustrating a hardware configuration of the ECU.
The ECU 30 includes a microcomputer 31 and an input / output interface (I / F) 32, and the microcomputer 31 and the input / output interface 32 are connected to each other by a bus 33. The input / output interface 32 is connected to the bus 34 of the in-vehicle network. Other ECUs are also connected to the bus 34, and the ECU 30 can perform cooperative control by communicating with the other ECUs.

  The microcomputer 31 includes a CPU (Central Processing Unit) 35, a ROM (Read Only Memory) 36, and a RAM (Random Access Memory) 37, which are connected to each other via an internal bus 38. The ROM 36 is composed of, for example, an EEPROM (Electronically Erasable and Programmable Read Only Memory), and the RAM 37 is composed of, for example, an SRAM (Static RAM).

  The CPU 35 of the microcomputer 31 controls the entire ECU 30. The ROM 36 stores various data such as an OS (Operating System), various programs, and parameters. The RAM 37 temporarily stores at least a part of the OS and application programs executed by the CPU 35, various data necessary for processing by the CPU 35, and learning values during engine control. The program stored in the ROM 36 realizes the function of the engine idling stabilization control device in addition to the program necessary for engine control, and includes at least a program for executing idling stabilization processing.

Next, the function of the idle stabilization control device in the ECU 30 realized by the hardware as described above will be described.
FIG. 3 is a block diagram showing functions of the idle stabilization control device in the ECU.

  The idle stabilization control device in the ECU 30 includes an idle instability detection unit 41, an instability cause determination unit 42, and a cause countermeasure unit 43. The idle instability detection unit 41 inputs a signal detected by the crank angle sensor 21 as a signal representing the engine speed, and monitors the fluctuation of the engine speed during idling and the idling state becomes unstable. Is detected. When the idle instability detection unit 41 detects idle instability, the instability cause determination unit 42 determines the cause of instability by changing the generated torque of the engine in the idle state. The cause countermeasure unit 43 corrects the instability cause determined by the instability cause determination unit 42 in a direction in which instability in the idle state is improved.

Next, the operation of the idle stabilization control device having the above functions will be described.
4 is a flowchart showing the flow of the entire process of the idle stabilization control device, FIG. 5 is an explanatory diagram showing an example of the idle instability detection method, and FIG. 6 is a flowchart showing the flow of the cause determination process.

  In the idle stabilization process, first, it is determined whether or not a start condition for this process is satisfied (step S1). That is, as a start condition of the idle stabilization process, for example, when the engine is being driven (the vehicle may or may not be stopped) and the accelerator pedal is not depressed for a predetermined time, or In the first place, it can be set at the time of low water temperature, low oil temperature, and when the idling is unstable, not within a predetermined time after starting.

  When the start condition for the idle stabilization process is established, the idle instability detector 41 monitors the fluctuation of the engine speed (step S2), and determines whether or not the idling is unstable (step S3). That is, when the engine is in idle operation, the output torque of the engine is controlled so as to obtain the necessary torque necessary to drive the engine depending on the state of the auxiliary load. As shown in FIG. 5, the engine speed is in the vicinity of the target speed. However, when the engine speed fluctuates greatly and constantly, the engine speed fluctuates beyond the normal range and enters a hunting state. Therefore, the determination of idle instability in step S3 measures the time during which the engine speed fluctuates outside the normal range, and determines that it is idle instability when that time becomes longer than a predetermined value. If the idle is not unstable, the process returns to step S1. However, if the idling speed determined to be unstable is in the vicinity of a low predetermined value, there is a risk that the engine will stall due to the execution of the next cause determination process. In this case, the process returns to step S1. It is good to.

  If the idle is unstable, a process for determining what is causing the idle instability is performed (step S4). In the cause determination process, as shown in FIG. 6, first, the output torque of the engine is varied (step S11), and as a result, it is determined whether or not the idle state changes (step S12).

  Here, the engine output torque can be varied by changing the intake air amount by the ISCV 9, changing the fuel injection amount by the injector 10, and changing the ignition timing by the igniter 14. In the preferred embodiment, first, it is determined whether or not the idle instability changes by changing the intake air amount. When the instability does not change due to the change of the intake air amount, the fuel injection amount is changed. Thus, the change in idle instability is determined, and if it still does not change, the ignition timing is changed to determine the change in idle instability. In addition, changes in the intake air amount, fuel injection amount, and ignition timing are usually controlled by adding correction terms to the reference values set as idle control, rather than directly changing their control target values. Although the target value is set, here, the engine output torque is varied by applying a predetermined coefficient to the correction term. Specifically, in changing the intake air amount, the control target value is changed by a method of multiplying the correction term at the time of idle control by, for example, 0.5.

  The intake air amount, the fuel injection amount, and the ignition timing are sequentially changed, and when the idle instability is first changed or improved, it can be identified as the cause of idle instability (step) S13). That is, assuming that the intake air amount, the fuel injection amount, and the ignition timing are changed in this order, for example, if the hunting is settled or worsens after the fuel injection amount is changed, the cause of the hunting is the fuel injection amount. It can be determined that it is not properly controlled.

  In the present embodiment, the intake air amount, the fuel injection amount, and the ignition timing are changed in this order, but this is changed in order from the parameters that are likely to cause idle instability. It is not necessary to limit to changing in order. In addition, when the control value is changed, if idle instability does not change even if a certain control value (for example, the intake air amount) is changed, the control value is returned to the original value and then the next control value (for example, the fuel injection amount) is changed. Even a method of changing may be a method of changing the next control value while maintaining the changed control value.

  If the intake air amount, the fuel injection amount, and the ignition timing are changed in this order, and the idle unstable state does not change, it is next determined whether or not the idle rotational speed is low (step S14), and the idle rotational speed is determined. If the number is lower than the predetermined value, the idle stabilization control is prohibited to avoid engine stall (step S15).

  If the idling speed is higher than the predetermined value, the engine load, that is, the torque required by the engine is varied (step S16), and as a result, it is determined whether or not the idling state changes (step S17). This identifies the cause of idle instability (step S18).

  Here, for example, the required torque of the engine increases the load on the auxiliary engine of the engine by setting the power generation requirement value of the alternator to the maximum or setting the refrigeration capacity to the maximum if the air conditioner is in operation. That is variable. Of course, if the alternator is generating electricity and the battery has a sufficient charge rate, this change in the required torque is when the power generation is prohibited or the refrigeration load of the current air conditioner is not very large. Alternatively, the operation of the air conditioner may be stopped or changed so as to reduce the auxiliary load on the engine. Thus, by changing the required torque of the engine, the ECU 30 performs cooperative control so as to vary the output torque of the engine in accordance with the changed required torque. As a result, the output torque of the engine is reduced. Has the same effect as making it variable.

  It should be noted that the process of changing the required torque of the engine, that is, the auxiliary load, is not performed when the idling speed is low, but is changed to increase the output torque so as to increase the idling speed. The necessary torque variable processing may be executed in cooperation with the above.

  Next, returning to FIG. 4, it is determined whether or not the idle stabilization control is prohibited during the cause determination process (step S5). If it is prohibited, the process returns to step S1. If the idle stabilization control is not prohibited, the cause-specific stabilization control is executed (step S6), and the cause / measure data regarding the stabilization control at that time is stored in the RAM 37 as a learning value (step S7). This is substantially the same as the cause determination process. For example, if it is determined that the cause of the idle instability is the intake air amount as a result of changing the correction term for the intake air amount in the cause determination process and the idling instability is changed or improved. In this cause stabilization control, the intake air amount is changed by applying a coefficient acting in a direction in which the idle unstable state is improved to the correction term of the intake air amount.

  The idle stabilization control is performed while the idle state continues. When the idle state is terminated, for example, when the accelerator pedal is depressed, the process returns to step S1.

  In order to cope with the case where the idle unstable state is temporary, after returning to the state before the cause determining process after the cause determining process in step S4, it is determined again whether or not the idle state is stabilized. If stable, return to step S1, or after executing the stabilization control in step S6, determine whether the idle state is stable, and if stable, execute the correction term being executed. A process for gradually returning to the previous value may be added.

  In step S7, the cause / countermeasure learning value is stored in the RAM 37 in the above-described stabilization process. This learning value is reflected in the next idle control of the ECU 30 as necessary, or in a dealer or the like. At the time of inspection, the learning value can be read from the RAM 37 and used as a reference when adjusting the idle control.

  As mentioned above, although this invention was explained in full detail about the preferable embodiment, this invention is not limited to this specific embodiment. For example, in the above-described embodiment, detection of idle instability is determined on the basis of fluctuations in engine speed. However, a vehicle vibration sensor is provided in a vehicle, for example, an engine block to monitor the vibration of the vehicle. When the vibration becomes larger than a predetermined level, it may be determined that the idle is unstable, or the determination based on the vibration of the vehicle and the determination based on the engine speed may be used in combination.

It is a schematic block diagram showing the structure around the engine of this Embodiment. It is a block diagram which illustrates the hardware constitutions of ECU. It is a block diagram which shows the function of the idle stabilization control apparatus in ECU. It is a flowchart which shows the flow of the whole process of an idle stabilization control apparatus. It is explanatory drawing which shows an example of an idle unstable detection method. It is a flowchart which shows the flow of a cause determination process.

Explanation of symbols

30 ECU
41 Idle Instability Detection Unit 42 Instability Cause Determination Unit 43 Cause Countermeasure Unit

Claims (6)

Idle instability detecting means for detecting fluctuations in the idling speed during idling based on a signal representing the engine speed and detecting instability in the idling state;
When the idle instability is detected by the idle instability detecting means, the instability cause determining means for determining the cause of instability by changing the torque generated by the engine in the idle state and changing the instability of the idle state. When,
Cause countermeasure means for correcting the instability cause determined by the instability cause determination means in a direction in which instability of the idle state is improved;
An idle stabilization control device for an engine characterized by comprising:   The instability cause determining means changes the generated torque of the engine by changing at least one of the intake air amount, the fuel injection amount, and the ignition timing, and as a result of the change in the generated torque, the instability of the idle state is improved or 2. The engine idling stabilization control apparatus according to claim 1, wherein when the engine is deteriorated, the control object that changes the generated torque is determined as the cause of instability.   The instability cause determining means changes the generated torque by changing an auxiliary load of the engine, and changes the generated torque when the instability of the idle state is improved or deteriorated as a result of the change in the generated torque. 3. The engine idle stabilization control device according to claim 2, wherein it is determined that the cause is instability.   The instability cause determination means prohibits the instability cause determination when the engine speed when the idle instability detection means determines that the idling instability is in the vicinity of a low predetermined value. 2. The engine idle stabilization control device according to claim 1, wherein   The instability cause determining means increases the generated torque by the instability cause determining means when the engine speed when the idle instability detecting means is determined to be idle unstable is near a low predetermined value. The engine idling stabilization control apparatus according to claim 1, wherein the cause of instability is determined by changing an auxiliary load in cooperation with the control to be performed. The engine idle stabilization control device according to claim 1, wherein the cause countermeasure means gradually restores the state before the correction execution when the idle state is stabilized after the correction for the cause of instability is performed. .

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