JP2011127439A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an engine from becoming inoperable by abnormality of an idle stop control system, in a control system mounting both functions of a fuel injection control system and the idle stop control system on one MPU. <P>SOLUTION: The MPU 12 is mounted with both functions of the fuel injection control system 17 and the idle stop control system 18 of expanding an idle stop area up to a speed reduction area before stopping a vehicle, and the idle stop control system 18 is provided with a brake negative pressure monitoring part 26 for monitoring brake negative pressure, and when the brake negative pressure is insufficient, output of an idle stop command is prohibited. A monitoring IC 13 is arranged for monitoring the existence of the abnormality of the brake negative pressure monitoring part 26 of the idle stop control system 18, and when detecting the abnormality of the brake negative pressure monitoring part 26, a signal of an injection pulse from the fuel injection control system 17 is preferentially selected to a signal of the idle stop command from the idle stop control system 18. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine having an idle stop function for automatically stopping the internal combustion engine when a predetermined automatic stop condition is satisfied during operation of the internal combustion engine (engine).

  A vehicle equipped with a conventional idle stop function is, for example, for engine control as described in Patent Document 1 (Japanese Patent Laid-Open No. 2007-331533) and Patent Document 2 (Japanese Patent Laid-Open No. 2009-121250). In many cases, an ECU and an ECU for idle stop control are provided separately. However, with this configuration, there is a problem that the number of ECUs (MPUs) mounted on the vehicle increases and costs increase.

  Therefore, there is one in which functions of both the fuel injection control system and the idle stop control system are implemented in one MPU.

JP 2007-331533 A JP 2009-121250 A

  By the way, the ECU mounted on the vehicle includes, in addition to the MPU, peripheral circuits such as an abnormality monitoring IC that monitors whether there is an abnormality of the MPU, a driver that drives the actuator, and the like. It is necessary to monitor the operation of the MPU having both the fuel injection control system function and the idle stop control system function with the abnormality monitoring IC, but if all the functions of this MPU are monitored with the abnormality monitoring IC, As a result, the processing load for abnormality monitoring needs to be increased, and the processing capability of the abnormality monitoring IC and MPU must be increased, resulting in an increase in cost.

  Therefore, in order to reduce the cost, only the main functions (for example, functions related to driving safety) of the MPU are monitored by the abnormality monitoring IC, and when an abnormality of the MPU is detected, the fuel injection valve is immediately switched to. It is considered that the engine is stopped by cutting the output of the injection pulse.

  However, in this configuration, once the abnormality monitoring IC detects an abnormality of the MPU and the engine is stopped, the engine cannot be restarted, and the vehicle cannot restart or retreat. .

  Further, in recent years, in order to expand the idle stop region to the deceleration region before stopping the vehicle and increase the fuel saving effect, the fuel is reduced when the vehicle enters a predetermined deceleration state during which the vehicle is decelerated. It is considered that the engine is automatically stopped by starting cutting.

  However, the brake negative pressure introduced into the brake booster from the engine intake system during vehicle deceleration may be insufficient, so if idle stop is executed during vehicle deceleration, the brake negative pressure is insufficient. The brakes may not work well. Further, when the MPU idle stop control system function is monitored by the abnormality monitoring IC, once the abnormality monitoring IC detects an abnormality in the idle stop control system and the engine is stopped, the vehicle is restarted. There arises a problem that starting and evacuation are impossible.

  Therefore, the present invention is an invention aimed at solving at least one of the above-mentioned problems.

  In order to solve the above problem, the invention according to claim 1 outputs an injection command for driving the fuel injection valve during operation of the internal combustion engine and outputs an injection command when a predetermined fuel cut condition is satisfied. A fuel injection control system function that stops the engine and a fuel cut command (hereinafter referred to as an “idle stop command”) for automatically stopping the internal combustion engine when a predetermined automatic stop condition is satisfied during operation of the internal combustion engine In the control device for an internal combustion engine in which the function of the idle stop control system is implemented in one MPU, either one command based on the combination of the command from the fuel injection control system and the command from the idle stop control system A command selection unit that selects and outputs the error is provided between the MPU and the fuel injection valve, and an abnormality is monitored for the presence or absence of an abnormality in the idle stop control system. The command selection unit is (1) when an abnormality of the idle stop control system is not detected by the abnormality monitoring unit, rather than an injection command from the fuel injection control system. (2) When an abnormality of the idle stop control system is detected by the abnormality monitoring unit, the idle stop command is selected from the fuel injection control system rather than the idle stop command from the idle stop control system. The injection command is selected with priority.

  In this configuration, the functions of both the fuel injection control system and the idle stop control system are implemented in one MPU, and furthermore, the monitoring target of the abnormality monitoring unit is limited to the idle stop control system, thereby reducing the cost. When the abnormality monitoring unit detects an abnormality in the idle stop control system while satisfying the condition, the injection stop command from the fuel injection control system is selected in preference to the idle stop command from the idle stop control system. When the system is abnormal, idle stop is prohibited, and the operation (fuel injection) of the internal combustion engine can be continued by an injection command from the fuel injection control system, so that the vehicle can be restarted or retreated.

  In this case, the idle stop control system may output an idle stop command by satisfying a predetermined automatic stop condition only when the vehicle is stopped. An idle stop command may be output when a predetermined automatic stop condition is satisfied even during vehicle deceleration. In this way, the idle stop area can be expanded to the deceleration area before the vehicle stops, and the fuel saving effect can be increased.

  However, there is a possibility that the brake negative pressure introduced into the brake booster from the intake system of the internal combustion engine during vehicle deceleration may be insufficient, so if idle stop is executed during vehicle deceleration, There is a possibility that the braking will become worse due to the lack.

  As a countermeasure against this, as in claim 3, there is provided brake negative pressure detecting means for detecting a brake negative pressure introduced into the brake booster from the intake system of the internal combustion engine, and the idle stop control system is configured to detect the brake negative pressure. A brake negative pressure monitoring unit that monitors whether or not a predetermined range of brake negative pressure is secured based on the detected value of the means, and the brake negative pressure of the predetermined range is not secured by the brake negative pressure monitoring unit It may be configured to include an idle stop permission / prohibition determination unit that prohibits the output of the idle stop command when it is determined.

  In this configuration, when the brake negative pressure monitoring unit determines that the predetermined range of brake negative pressure is not secured, the output of the idle stop command can be prohibited by the idle stop permission / prohibition determination means. It is possible to prevent the idling stop from being executed in a state where the negative pressure is insufficient, and to prioritize the securing of the brake negative pressure over the idling stop, so that it is possible to prevent the braking from becoming worse.

  In this case, as in claim 4, the abnormality monitoring unit may monitor the presence or absence of abnormality only in the brake negative pressure monitoring unit in the idle stop control system. In this configuration, the monitoring target of the abnormality monitoring unit can be limited to the brake negative pressure monitoring unit, which is an important part for avoiding the badness of the brake, reducing the processing load for abnormality monitoring. If the brake negative pressure monitoring unit becomes abnormal, it is erroneously determined that the brake negative pressure has been secured and the idle stop has occurred. Can be prevented in advance, and it can be avoided that the braking becomes poor.

FIG. 1 is a block diagram showing the configuration of an engine control system in one embodiment of the present invention. FIG. 2 is a circuit diagram showing the configuration of the signal selection circuit. FIG. 3 is a time chart for explaining the relationship between input and output signals of the signal selection circuit. FIG. 4 is a flowchart for explaining the contents of the abnormality monitoring process.

Hereinafter, an embodiment embodying a mode for carrying out the present invention will be described.
First, the configuration of an engine (internal combustion engine) control device will be described with reference to FIG.
The ECU 11 that is an engine control device includes an MPU 12, a monitoring IC 13 (abnormality monitoring unit), a signal selection circuit 14 (command selection unit), and peripheral circuits such as a driver 16 that drives the fuel injection valve 15. Yes.

  The functions of both the fuel injection control system 17 and the idle stop control system 18 are mounted on the MPU 12. Here, the fuel injection control system 17 includes an injection amount calculation unit 19, a normal fuel cut command unit 20, and an injection pulse generation unit 21, and the injection amount calculation unit 19 determines the engine operating state (intake air amount, intake air amount). An injection pulse generator that calculates the fuel injection amount so that the actual air-fuel ratio matches the target air-fuel ratio based on the outputs of various sensors that detect the pipe pressure, engine speed, cooling water temperature, exhaust gas air-fuel ratio, etc. To 21.

  The normal time fuel cut command unit 20 outputs a fuel cut command (high speed fuel cut command) to the injection pulse generation unit 21 when the engine rotational speed exceeds the allowable upper limit rotational speed, and the engine rotational speed is predetermined. A fuel cut command (deceleration fuel cut command) is output to the injection pulse generator 21 when the throttle is fully closed (accelerator fully closed) in the region of the rotational speed or higher.

  When the fuel cut command is not input from the normal fuel cut command unit 20, the injection pulse generation unit 21 generates an injection pulse having a pulse width corresponding to the fuel injection amount calculated by the injection amount calculation unit 19 to generate a signal selection circuit 14. No injection pulse is generated during a period in which the fuel cut command is input from the normal fuel cut command unit 20 (the injection pulse to the signal selection circuit 14 is cut).

  On the other hand, the idle stop control system 18 includes a vehicle-side system abnormality diagnosis unit 22, a driver intention determination unit 23, an idle stop system request calculation unit (hereinafter referred to as “ISS request calculation unit”) 24, an engine stop / The restart determination unit 25, the brake negative pressure monitoring unit 26, and an idle stop permission / prohibition determination unit 27 (idle stop permission / prohibition determination means) are configured.

  Here, the vehicle-side system abnormality diagnosis unit 22 includes a brake negative pressure sensor (brake negative pressure detecting means) that detects a brake negative pressure introduced from the engine intake system into the brake booster, a cooling water temperature sensor, a battery voltage sensor, Abnormal diagnosis of each system on the vehicle side is executed based on outputs of various sensors mounted on the vehicle such as a hydraulic sensor, a crank angle sensor, an intake air amount sensor, an intake pipe pressure sensor, a throttle sensor, and the like.

  The driver intention determination unit 23 is a driver's intention to stop the vehicle based on outputs from an accelerator sensor that detects an accelerator opening, a brake sensor that detects whether a brake is activated or deactivated, a vehicle speed sensor that detects a vehicle speed, and the like. It is determined whether or not there is an intention to restart / re-accelerate the vehicle that has been idle-stopped. For example, even when the vehicle is running, it is determined that the driver has an intention to stop the vehicle if the accelerator is fully closed and the brake is activated to enter a predetermined deceleration state in which it is determined that the vehicle will stop. Further, if the accelerator is fully closed and the brake is operated while the vehicle is stopped, it is determined that the driver intends to continue the vehicle stop. Further, when the accelerator is depressed from the state where the accelerator is fully closed and the brake is operated during the idle stop, or when the brake is released, it is determined that the driver intends to start and reaccelerate the vehicle.

  The ISS request calculation unit 24 calculates whether or not there is an idle stop request and a restart request based on information input from the vehicle-side system abnormality diagnosis unit 22 and the driver intention determination unit 23, and an engine stop / restart determination unit 25. When the idle stop request is input from the idle stop request calculation unit 24, the engine is determined to be stopped and an idle stop command (fuel cut command) is output to the idle stop permission / prohibition determination unit 27. Thereafter, when a restart request is input from the idle stop request calculation unit 24, the engine stop / restart determination unit 25 determines that the engine is restarted and cancels the idle stop command (engine stop / restart determination unit). The output of the idle stop command to 25 is stopped).

  The brake negative pressure monitoring unit 26 determines whether or not the brake negative pressure detected by the brake negative pressure sensor is within a predetermined range in which the brake can be secured, and permits / inhibits a signal corresponding to the determination result. It outputs to the determination part 27.

  The idle stop permission / prohibition determination unit 27 is input from the engine stop / restart determination unit 25 when the brake negative pressure monitoring unit 26 determines that the brake negative pressure within a predetermined range is secured. The idle stop command (high level signal) is output to the signal selection circuit 14 as it is. On the other hand, when it is determined by the brake negative pressure monitoring unit 26 that the brake negative pressure within the predetermined range is not secured (that is, the brake negative pressure is insufficient), the engine stop / restart determination unit 25 issues an idle stop command. However, even if the idle stop permission / prohibition determination unit 27 is input, the output of the idle stop command to the signal selection circuit 14 is prohibited. As a result, when the brake negative pressure within the predetermined range is not secured, the engine operation (fuel injection) is continued without executing the idle stop even if the predetermined automatic stop condition (idle stop condition) is satisfied. It has come to be.

  The monitoring IC 13 monitors whether the idle stop control system 18 of the MPU 12 is abnormal. In this case, the monitoring IC 13 may monitor the operation of at least the brake negative pressure monitoring unit 26 and the idle stop permission / prohibition determination unit 27 in the idle stop control system 18, but in this embodiment, By limiting the monitoring target of the monitoring IC 13 to only the brake negative pressure monitoring unit 26, which is an important part for avoiding the deterioration of the braking effectiveness, the processing load for monitoring the abnormality is reduced and the cost is reduced. To make it possible.

  In the present embodiment, the monitoring IC 13 monitors whether or not only the brake negative pressure monitoring unit 26 of the MPU 12 has an abnormality by repeatedly executing the abnormality monitoring process of FIG. . In this abnormality monitoring process, first, in step 101, it is determined whether or not an idle stop command is output from the engine stop / restart determination unit 25 of the idle stop control system 18, and the idle stop command must be output. If so, this routine is terminated.

  If it is determined in step 101 that an idle stop command is output from the engine stop / restart determination unit 25 of the idle stop control system 18, the process proceeds to step 102 to check whether there is an abnormality in the brake negative pressure monitoring unit 26. A test input value and a test threshold value used for determination are generated by the monitoring IC 13.

  Thereafter, the process proceeds to step 103a, where the monitoring IC 13 compares the test input value generated by the monitoring IC 13 with the test threshold value, and stores the comparison result (which is larger or smaller). . In parallel with this processing, the process proceeds to step 103b, where the test input value and the test threshold value generated by the monitoring IC 13 are transmitted to the brake negative pressure monitoring unit 26 of the MPU 12, and the brake negative pressure monitoring unit 26 The test input value is compared with the test threshold value, and the comparison result (which is larger or smaller) is returned to the monitoring IC 13.

  Thereafter, the process proceeds to step 104, where the two comparison results are collated by the monitoring IC 13, and in the next step 105, it is determined whether or not the two comparison results match, and the two comparison results are determined. If there is a match, it is determined that there is no abnormality (normal) in the brake negative pressure monitoring unit 26, the process proceeds to step 106, and an MPU abnormality non-existence signal (high level signal) is output to the signal selection circuit 14, and the above two comparison results If they do not match, it is determined that there is an abnormality in the brake negative pressure monitoring unit 26, the process proceeds to step 107, and an MPU abnormality presence signal (low level signal) is output to the signal selection circuit 14.

  As shown in FIG. 2, the signal selection circuit 14 has three input terminals and one output terminal, and each input terminal has an injection pulse signal from the injection pulse generation unit 21 of the fuel injection control system 17. Then, an idle stop command signal from the idle stop permission / prohibition determination unit 27 of the idle stop control system 18 and an MPU abnormality monitoring result signal from the monitoring IC 13 are input, and based on a combination of these three input signals The final injection pulse is determined and output to the driver 16 to operate the engine, or the final injection pulse is cut, and one of fuel cut at high revolution, fuel cut at deceleration, and idle stop is executed.

  The signal selection circuit 14 is configured by a logic circuit including a NAND circuit 31 and an AND circuit 32, and two input terminals of the NAND circuit 31 are connected to an idle stop from the idle stop permission / prohibition determination unit 27 of the idle stop control system 18. A stop command signal and an MPU abnormality monitoring result signal from the monitoring IC 13 are input, and a signal output from the output terminal of the NAND circuit 31 is input to one input terminal of the AND circuit 32. The other input terminal of the AND circuit 32 receives an injection pulse signal from the injection pulse generation unit 21 of the fuel injection control system 17, and the final injection pulse is output or cut from the output terminal of the AND circuit 32.

  Thereby, the relationship between the input and output signals of the signal selection circuit 14 is as shown in FIG. In other words, the signal selection circuit 14 performs fuel injection when the MPU abnormality monitoring result signal from the monitoring IC 13 is a high-level signal that means “no MPU abnormality” (when there is no abnormality in the brake negative pressure monitoring unit 26). The idle stop command signal from the idle stop control system 18 is selected with priority over the injection pulse signal from the control system 17. Therefore, when there is no abnormality in the brake negative pressure monitoring unit 26, if an idle stop command (high level signal) is output from the idle stop control system 18, the final injection pulse is cut and idle stop is executed. If an idle stop command (high level signal) is not output from the stop control system 18, the injection pulse from the fuel injection control system 17 is output as it is as the final injection pulse, and the engine operation (fuel injection) is continued. In the case of fuel cut at high rotation and fuel cut at deceleration, the injection pulse from the fuel injection control system 17 is cut, so that the final injection pulse is also cut, and fuel cut at high rotation and fuel cut at deceleration Is executed.

  On the other hand, when the signal of the MPU abnormality monitoring result from the monitoring IC 13 is a low level signal meaning “MPU abnormality present” (when the brake negative pressure monitoring unit 26 is abnormal), the signal selection circuit 14 The injection pulse signal from the fuel injection control system 17 is selected in preference to the idle stop command signal from the idle stop control system 18. Therefore, when there is an abnormality in the brake negative pressure monitoring unit 26, even when an idle stop command (high level signal) is output from the idle stop control system 18, the injection pulse from the fuel injection control system 17 is used as the final injection as it is. Output as pulses to continue engine operation (fuel injection). However, in the case of fuel cut at high revolution or fuel cut at deceleration, the injection pulse from the fuel injection control system 17 is cut, so that the final injection pulse is also cut, and fuel cut at high revolution or at deceleration Fuel cut is executed.

  According to the present embodiment described above, the functions of both the fuel injection control system 17 and the idle stop control system 18 are implemented in one MPU 12, and the monitoring target of the monitoring IC 13 is limited to the idle stop control system 18. Thus, when an abnormality in the idle stop control system 18 is detected by the monitoring IC 13 while satisfying the cost reduction requirement, the injection command from the fuel injection control system 17 is more effective than the idle stop command from the idle stop control system 18. Priority is selected so that idling stop can be prohibited when the idling stop control system 18 is abnormal, and the operation of the engine can be continued by the injection command from the fuel injection control system 17, so that the vehicle is restarted or retreated. Driving is possible.

  Moreover, as in this embodiment, the idle stop control system 18 is configured to output an idle stop command when a predetermined automatic stop condition is satisfied even during deceleration of the vehicle in addition to when the vehicle is stopped. There is an advantage that the area can be expanded to the deceleration area before the vehicle stops, and the fuel saving effect can be increased.

  In this case, the brake negative pressure introduced into the brake booster from the engine intake system during vehicle deceleration may be insufficient. There is a possibility that the braking will become worse due to the lack.

  As a countermeasure, in this embodiment, the idle stop control system 18 includes a brake negative pressure monitoring unit 26 that monitors whether or not a predetermined range of brake negative pressure is secured based on a detection value of the brake negative pressure sensor, Since the brake negative pressure monitoring unit 26 includes an idle stop permission / prohibition determination unit 27 that prohibits output of an idle stop command when it is determined that a predetermined range of brake negative pressure is not secured. Since the output of the idle stop command can be prohibited by the idle stop permission / prohibition determination unit 27 when the brake negative pressure monitoring unit 26 determines that the brake negative pressure within a predetermined range is not secured, the brake negative pressure is detected during vehicle deceleration. It is possible to prevent the idle stop from being executed when there is a shortage of brakes, and the brake negative pressure is higher than the idle stop. To be able to prioritize ensured, it can be avoided handed brake is deteriorated.

  In addition, in this embodiment, the monitoring target of the monitoring IC 13 is configured to be limited to the brake negative pressure monitoring unit 26 which is an important part for avoiding the badness of the brake. The processing load can be reduced and the cost can be reduced, and when the brake negative pressure monitoring unit 26 becomes abnormal, the brake negative pressure is secured in a state where the brake negative pressure within a predetermined range is not secured. It is possible to prevent the idling stop from being erroneously determined and to prevent the braking from becoming worse.

  However, according to the present invention, the monitoring target of the monitoring IC 13 may be both the brake negative pressure monitoring unit 26 and the idle stop permission / prohibition determination unit 27, and the other parts of the idle stop control system 18 are connected to the monitoring IC 13. It may be added to the monitoring target.

Further, the idle stop control system 18 may execute idle stop only while the vehicle is stopped.
In addition, the present invention reverses the relationship between the high level / low level of the MPU abnormality monitoring result signal from the monitoring IC 13 and the relationship between the high level / low level of the idle stop command signal from the idle stop control system 18. (In this case, the logic circuit configuration of the signal selection circuit 14 may be changed in accordance with the change of the high level / low level of the signal). Various modifications can be made without departing from the gist, such as addition of system functions.

  DESCRIPTION OF SYMBOLS 11 ... ECU, 12 ... MPU, 13 ... Monitoring IC (abnormality monitoring part), 14 ... Signal selection circuit (command selection part), 15 ... Fuel injection valve, 17 ... Fuel injection control system, 18 ... Idle stop control system, DESCRIPTION OF SYMBOLS 19 ... Injection amount calculating part, 20 ... Normal fuel cut command part, 21 ... Injection pulse production | generation part, 22 ... Vehicle side system diagnostic part, 23 ... Driver intention determination part, 24 ... Idle stop system request | requirement calculating part (ISS request | requirement) Calculation unit), 25 ... Engine stop / restart determination unit, 26 ... Brake negative pressure monitoring unit, 27 ... Idle stop permission / prohibition determination unit (idle stop permission / prohibition determination means)

Claims (4)

A function of a fuel injection control system for outputting an injection command for driving the fuel injection valve during operation of the internal combustion engine and stopping the output of the injection command when a predetermined fuel cut condition is satisfied; and during operation of the internal combustion engine An internal combustion engine in which a function of an idle stop control system for outputting a fuel cut command (hereinafter referred to as an “idle stop command”) for automatically stopping the internal combustion engine when a predetermined automatic stop condition is satisfied is implemented in one MPU In the engine control device,
Command selection that is provided between the MPU and the fuel injection valve and selects and outputs one of the commands based on a combination of a command from the fuel injection control system and a command from the idle stop control system And
An abnormality monitoring unit that monitors whether there is an abnormality in the idle stop control system,
The command selector (1) prioritizes the idle stop command from the idle stop control system over the injection command from the fuel injection control system when no abnormality of the idle stop control system is detected by the abnormality monitoring unit. (2) When an abnormality of the idle stop control system is detected by the abnormality monitoring unit, the injection command from the fuel injection control system is prioritized over the idle stop command from the idle stop control system. A control device for an internal combustion engine, wherein   The idle stop control system outputs an idle stop command when a predetermined automatic stop condition is satisfied while the vehicle is stopped, and further outputs an idle stop command when the predetermined automatic stop condition is satisfied even during vehicle deceleration. The control device for an internal combustion engine according to claim 1. Brake negative pressure detecting means for detecting the brake negative pressure introduced into the brake booster from the intake system of the internal combustion engine,
The idle stop control system includes a brake negative pressure monitoring unit that monitors whether a predetermined range of brake negative pressure is secured based on a detection value of the brake negative pressure detection unit, and the brake negative pressure monitoring unit 3. An internal combustion engine according to claim 1, further comprising idle stop permission / prohibition determination means for prohibiting output of an idle stop command when it is determined that a predetermined range of brake negative pressure is not secured. Control device.   The control apparatus for an internal combustion engine according to claim 3, wherein the abnormality monitoring unit monitors whether or not only the brake negative pressure monitoring unit in the idle stop control system is abnormal.

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