JP2007224832A - Diagnostic equipment of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive means for diagnosing the starting performance of an internal combustion engine and estimating the factor of starting deterioration, to reduce the cost of check/maintenance, and to prevent a starting malfunction. <P>SOLUTION: The diagnostic equipment of an internal combustion engine equipped with a generator, a battery and a starter comprises a sensor input means for processing a crank rotational number of the internal combustion engine, and a battery voltage; a control means for controlling the starting state of the internal combustion engine; a switch signal means for processing a key switch signal for controlling at least either an electrical system of a vehicle or the starter; and a diagnostic means for diagnosing the electrical system based on an output from the switch signal means by using the output signal outputted from the sensor input means, the control means and the SW signal means, and also diagnosing the starting performance or startability of the internal combustion engine based on the correlation of the output signal from the sensor input signal with the output signal from the control means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a diagnostic apparatus for an internal combustion engine that diagnoses the starting performance of the internal combustion engine and detects a factor of deterioration in starting performance.

  An internal combustion engine such as gasoline or diesel is started by cranking by a starter such as a starter motor. At this time, it is known that the higher the water temperature and the battery voltage, the better the startability (Patent Document 1). As a technique for preventing the startability from deteriorating, for example, the deterioration of combustion due to insufficient compression is determined from the battery voltage and the engine speed. There are proposed a method of detecting and preventing deterioration of startability by fuel injection or throttle operation (Patent Documents 2 and 3) and a method of switching the starter drive circuit when the battery voltage is low (Patent Document 4).

JP-A-6-249021 JP 2000-80953 A JP 2000-356152 A Japanese Patent Laid-Open No. 2005-20795

  However, in the conventional invention, when startability deteriorates in the market, no means for specifying the cause of start deterioration is provided. For example, in Reference 1-4, only limited deterioration factors of startability such as battery deterioration and insufficient compression are provided. Only consider. Also, since the start performance has not been diagnosed, the only way to get the dealer to investigate the factors after feeling dissatisfied or uneasy about the startability is that it takes time and inspection costs, and the user starts If the performance is not noticed, the engine may start to fail.

  The present invention has been made in view of such circumstances, and its object is to provide a diagnostic device that evaluates the starting performance of an internal combustion engine and detects the cause of deterioration in starting performance, thereby reducing costs and preventing starting failures. Is to realize.

The above object is provided in an internal combustion engine diagnostic apparatus including a generator, a battery, and a starting device.
Sensor input means for processing the crank speed and battery voltage of the internal combustion engine;
Control means for controlling the starting state of the internal combustion engine;
Switch signal means for processing a key switch signal for controlling at least one of an electric system of a vehicle and the starter; and
The output signal output from the sensor input means, the control means, and the switch signal means is used, and the electrical system diagnosis is performed based on the output from the switch signal means, and the output signal from the sensor input means and the It is achieved by an internal combustion engine diagnostic device comprising diagnostic means for diagnosing the starting performance or startability of the internal combustion engine based on the correlation of output signals from the control means.

  In the present invention, since the degree of correlation between the output signals obtained from the existing sensor input means, control means and switch signal means is compared with the normal state assumed in advance, the starting performance is diagnosed to evaluate the low performance. Cost-effective startability diagnosis can be realized.

The above object is also provided in a diagnostic apparatus for an internal combustion engine including a generator, a battery, and a starting device.
Means for detecting the rotational speed of the internal combustion engine; means for detecting the battery voltage;
Switch signal means for processing a key switch signal for controlling an energization state of at least one of an electric system of the vehicle and a starter; and
Means for detecting the control state of the internal combustion engine or the drive state or drive signal of the actuator, and the change characteristic of the battery voltage from the key switch signal ON state to the complete explosion to the first idle of the internal combustion engine or the internal combustion engine And a diagnostic means for diagnosing a part corresponding to the detecting means at a predetermined timing for each diagnostic item after the key switch is turned on (startability). This is achieved by a diagnostic device for an internal combustion engine characterized by the following. By using the output of the switch signal processing in the present invention, it is possible to easily perform a complicated state determination that changes instantaneously at start-up, such as energization start, cranking, combustion start, and idling, and diagnosis is divided into each state. By doing so, the startability deterioration factor becomes easy.

  The above object is characterized in that at least one of a generator, a starting device, a battery, an internal combustion engine, and a relay is diagnosed based on the output of the switch signal means in order to diagnose the starting performance of the internal combustion engine. Achieved by institutional diagnostic equipment. In the present invention, it is possible to easily carry out diagnosis according to the cause of deterioration of startability.

  Further, the above object is achieved by an internal combustion engine diagnosis device that diagnoses an abnormality of the battery based on the battery voltage or a terminal voltage of the battery and a crank rotational speed of the internal combustion engine.

  In order to achieve the above object, an internal combustion engine diagnostic device is characterized in that an abnormality of the starting device is diagnosed based on the battery voltage and the crank rotational speed when the starting device is operating. Is done.

  In order to achieve the above object, an abnormality of the generator is diagnosed based on the battery voltage and the crank speed after the starter is activated and stopped, and is achieved by an internal combustion engine diagnostic device. Is done.

  In order to achieve the above object, the combustion abnormality of the internal combustion engine is diagnosed on the basis of the battery voltage, the crank rotation speed, and the parameters of the control processing unit while the starter operates and stops. This is achieved by a diagnostic device for an internal combustion engine.

  In order to achieve the above object, an internal combustion engine diagnostic apparatus is characterized in that an abnormality of a relay driven by the key switch is diagnosed based on a battery voltage immediately before the starter operates.

  In the present invention, diagnosis of a relay, a starter, an internal combustion engine, an alternator, and a battery, which cause startability deterioration, is performed at an appropriate timing by the output of the switch output means, using information such as battery voltage and crank rotational speed that can be easily detected. be able to.

  By implementing the present invention, startability diagnosis can be realized at low cost, and start-up failure can be prevented. In addition, since the cause of the starting failure can be estimated, the cost of inspection and repair can be reduced. Further, by implementing the present invention, it is possible to evaluate the starting performance and detect a sign of the deterioration of the starting, and it is possible to implement an appropriate measure before falling into the starting impossible.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an embodiment of the present invention. The diagnostic device of the present invention is implemented as a program of the ECU 1 and is obtained from a sensor input means 102 for processing the voltage of the battery 2 storing the electric power generated by the alternator 5, the crank rotational speed of the internal combustion engine 3, the water temperature, the air temperature, the atmospheric pressure or the like. Start performance based on sensor information obtained, switch information obtained from the SW input means 103 that processes the key switch signal and controls the starter 4, and control state information obtained from the control means 104 that controls the internal combustion engine 3. The engine has a startability diagnosis means 101 that detects deterioration and identifies an abnormality factor. When the startability diagnosing means 101 detects the deterioration of the starting performance, it turns on the warning lamp 7, displays an abnormal message, or communicates outside the ECU.

  FIG. 22 shows an example of a correlation (correlation between battery voltage and engine speed) used for diagnosing start-up performance. The voltage is low because the starter is driven near the cranking speed, and the generated voltage of the alternator is near the standard voltage of the battery near the idle speed. Since this correlation varies somewhat depending on the temperature and the vehicle, there is a certain distribution even under normal conditions. In this distribution, if the starting performance is good, the correlation between the voltage and the rotational speed is located near the center of the distribution, but the correlation moves toward the end of the distribution as the startability deteriorates. The starting performance can be evaluated simply by comparing the voltage at the cranking speed and the idling speed at the normal time, but preferably the correlation between the battery voltage at the starting time and the speed is used to determine the normal performance. It is preferable to evaluate the starting performance in comparison with the correlation. Although a method using two sensor information of the engine speed and the battery voltage has been described here for simplicity, a control signal for the internal combustion engine may be added thereto. Specific methods for comparing correlations include methods used for pattern matching, such as MT method (evaluation based on Mahalanobis distance with normal state as reference space) and neural network (evaluation using neural network with normal state as teacher signal). it can.

  FIG. 2 shows an example of possible startability diagnosis based on the battery voltage at the start. In the relay diagnosis, an abnormality is detected based on a voltage drop caused by the key switch (SW) operation before the starter switch (SW) is turned on. In the battery diagnosis, the voltage drop waveform after the starter SW is turned on. In the starter diagnosis, the voltage fluctuation during cranking when the starter SW is in the ON state. In the internal combustion engine diagnosis, the voltage fluctuation before and after the starter SW is turned off. Then, the abnormality is detected based on the voltage fluctuation after a predetermined time after the starter SW is turned off.

  FIG. 3 shows an example of a diagnosis that is possible depending on the number of revolutions at the time of start. In the starter diagnosis, an abnormality is detected based on the rotation speed during cranking when the starter SW is ON. Further, in the internal combustion engine diagnosis, an abnormality is detected based on the behavior of the rotational speed before and after the starter SW is turned off or the peak rotational speed, and in the alternator diagnosis, based on the rotational speed a predetermined time after the starter SW is turned off. Hereinafter, each abnormality diagnosis method will be described in more detail.

  Since the alternator is not driven before the engine starts in this way, relay diagnosis based on voltage changes can be realized, and battery diagnosis can be realized using the increase in internal resistance of the battery that increases when an abnormality occurs because a large current flows when the starter starts. The starter diagnosis can be realized by estimating the rotational load during cranking from the voltage, and the diagnosis of the internal combustion engine can be realized from the rotation fluctuation until idling and the correlation of the control state or control signal, and from the rotation speed and voltage at idling Alternator diagnosis can be realized. Further, since the state of the engine can be determined by the starter SW, it is possible to detect the startability deterioration factor as described below.

  An embodiment of relay diagnosis using the present invention will be described with reference to FIGS. According to the present embodiment, the abnormality of the relay (short circuit or always open) can be diagnosed only by the switch information and the battery voltage, so that the cause of the starting failure can be easily identified at a low cost. Further, if this embodiment is executed when the engine is stopped, overdischarge of the battery due to a relay short circuit can be prevented.

FIG. 4 is an example of a flowchart of relay diagnosis in the present invention, which is executed at an interval of 10 ms in the ECU, for example. In step S401, sensor input processing is performed. In the sensor input process, the battery voltage is acquired by AD conversion and stored in the variable VB. Next, in step S402, SW input processing is performed. In the SW input process, the state of each SW is stored in each SW based on the signal input from the key SW. In this example, the accessory switch is stored in ACC SW, the ignition switch is stored in IGN SW, and the starter switch is stored in ST SW. In step S403, it is compared whether or not each SW state is different from the previous SW state. If not, the diagnosis process is terminated. If not, the process proceeds to step S404. In step S404, it is evaluated whether or not the absolute value (auxiliary load potential) of the difference between the previous battery voltage, which is the battery voltage before the switch state is changed, and the battery voltage after the switch state is changed is greater than the reference voltage displacement. . The reference voltage displacement here is an amount generated by the electric load of the auxiliary machine activated by the switch state, and may be a predetermined amount, or may be a learning of the displacement when the engine is first started with the battery attached. When the auxiliary machine load potential is larger than the reference voltage displacement in step S404, the process proceeds to step S405, where it is determined that the relay is normal, and a diagnosis end process (for example, a diagnosis completion flag is set) regarding the changed SW is performed. If the auxiliary machine load potential is smaller than the reference voltage displacement in step S404, it is determined that the catcher has not been turned on, and relay abnormality processing (for example, a relay abnormality flag corresponding to the corresponding SW is set and a warning lamp blinks) is performed. .

FIG. 5 is an example of a time chart when the relay is normal. When the accessory switch (ACC SW) is turned on, the voltage drops due to an electrical load such as audio, and when the ignition (IGN SW) is turned on, power is turned on to various electric devices (for example, fuel pumps), and the voltage further drops. To do. When the starter switch (ST SW) is turned on, a large current flows through the starter device, causing a voltage drop due to the internal resistance of the battery. When the starter switch is turned off, the electric load of the starter device is lost and the voltage rapidly increases.

FIG. 6 is an example of a time chart when the relay of the ignition switch is abnormal. IGN when ignition relay breaks and stops energizing or is left energized
Even if SW is changed, the voltage VB does not change. Therefore, in such a state, it is determined that the relay is abnormal and a relay abnormality flag is set.

  Next, an embodiment of battery diagnosis according to the present invention will be described with reference to FIGS. According to the present embodiment, it is possible to easily detect an abnormality of the battery only with the switch information, the rotation speed, and the voltage, and it is also possible to detect a caution state due to insufficient charging by using the history of the minimum voltage.

  FIG. 7 is an example of a flowchart of battery diagnosis according to the present invention, and is executed at intervals of 10 ms in the ECU, for example. In step S701, sensor input processing is performed, and the battery voltage is stored in VB and the rotation speed is stored in NE. In step S702, switch input processing is performed. For example, the starter SW signal is stored in the ST SW.

In step S703, it is compared whether or not the rotational speed NE is smaller than a reference rotational speed (for example, 500 rpm). If smaller, the process proceeds to step S704, and if not, the process ends. In step S704, whether the key state is the starter ON state is determined based on the value of ST SW. If the starter is ON, the process proceeds to step S705. Otherwise, the process proceeds to step S706. In step S705, a minimum voltage recording process is performed. Here, for example, the current voltage VB and the recorded minimum voltage VBmin are compared. If VB is smaller than VBmin, VB is stored in VBmin, so that the voltage drop based on the internal resistance of the battery can be recorded. In step S706, it is compared whether the minimum voltage VBmin is larger than the reference minimum voltage. If it is larger, the process proceeds to step S707. If not, the process proceeds to step S708. In step S707, battery normal processing is performed. Here, for example, a battery diagnosis end flag indicating that battery diagnosis has been performed may be set. In step S708, battery abnormality processing is performed. Here, a battery abnormality flag is set and a warning lamp is turned on or a warning message is presented by voice or image.

FIG. 8 is an example of a time chart when the battery is normal. Starter switch (ST
While SW) is on, the voltage drops significantly, but this initial voltage drop is greatest and this value is recorded as the lowest voltage VBmin.

  FIG. 9 is an example of a time chart when the battery is abnormal. When the starter switch is turned on, the voltage drop increases, VBmin becomes smaller than the reference minimum voltage, and it is determined that the battery is abnormal, and the battery abnormality flag is set.

  According to the flowchart shown in FIG. 7, VBmin holds the lowest voltage in the past, but it is possible to make a diagnosis using history by clearing VBmin and storing the value in a buffer each time the engine is started. .

  A diagnosis method using the history of the minimum voltage VBmin will be described with reference to FIG. In the case of a lead storage battery, lead sulfate adheres to the electrode due to deterioration or overdischarge, and the internal resistance increases. Therefore, as described above, the abnormality of the battery can be diagnosed by the magnitude of the minimum voltage when the starter is in operation. Further, when the state of charging is further insufficient, the amount of lead sulfate adhering to the electrode varies with a minimum voltage that is not constant. Since this variation becomes large when the amount of charge is insufficient, as shown in FIG. 10, it is possible to diagnose a battery requiring attention that is insufficiently charged based on the dispersion of the minimum voltage.

  Next, an embodiment of the starter diagnosis according to the present invention will be described with reference to FIGS. According to the present embodiment, an abnormality of the starter can be easily detected based on the switch information, the rotation speed, and the voltage.

  FIG. 11 is an example of a flowchart of starter diagnosis according to the present invention, which is executed, for example, at intervals of 10 ms in the ECU. In step S1101, sensor input processing is performed, and the battery voltage is stored in VB and the rotation speed is stored in NE. In step S1102, switch input processing is performed. For example, the starter SW signal is stored in the ST SW. In step S1103, it is compared whether or not the rotational speed NE is smaller than a reference rotational speed (for example, 500 rpm). If smaller, the process proceeds to step S1104. If not, the process is terminated. In step S1104, whether the key state is the starter ON state is determined based on the value of ST SW. If the starter is ON, the process proceeds to step S1105. Otherwise, the process proceeds to step S1106. In step S1105, voltage waveform processing is performed. Here, voltage fluctuations (cycle, amplitude) due to load fluctuations caused by the compression process cylinder during cranking, average voltage during cranking, and the like are extracted. In step S1106, it is determined whether the voltage waveform pattern at the time of cranking is a predetermined pattern. If it is the predetermined pattern, the process proceeds to step S1107, and if not, the process proceeds to step S1108. In step S1107, the starter normal process is performed, and for example, a flag that the starter diagnosis is completed is set. In step S1108, starter abnormality processing is performed. For example, a starter abnormality flag is set, and a warning lamp is turned on and a warning message is presented by sound or image.

  FIG. 12 is an example of a time chart when the starter is normal. While the starter is turned on and cranked, the load fluctuates due to the influence of the cylinder in the compression process, and voltage fluctuations according to the cranking speed and the cranking load occur.

  FIG. 13 is an example of a time chart when the starter is abnormal. When the starter is abnormal, heat is generated and the internal resistance is increased, so that the rotational speed is decreased and the period of voltage fluctuation is also increased. Therefore, the average voltage and period are monitored, and when the average voltage decreases or the period becomes longer, it is determined that the starter is abnormal, and a starter abnormality flag is set.

  FIG. 14 shows the relationship between the average voltage and the starter abnormality in the period or amplitude. If normal, the average voltage, period, and amplitude during cranking are in a predetermined range. For example, if the gear is not engaged, the average voltage is larger than the predetermined range and the period is shortened. Or, conversely, when the average voltage is small, there is a possibility of battery abnormality, but this can be separated from battery abnormality and starter abnormality by carrying out the battery diagnosis shown in the second embodiment.

  Next, an embodiment of alternator diagnosis according to the present invention will be described with reference to FIGS. According to the present embodiment, the abnormality of the alternator can be easily detected based on the switch information, the rotation speed, and the voltage.

  FIG. 15 is an example of a flowchart of starter diagnosis according to the present invention, which is executed, for example, at an interval of 10 ms in the ECU. In step S1501, sensor input processing is performed, and the battery voltage is stored in VB and the rotation speed is stored in NE. In step S1502, switch input processing is performed. For example, the starter SW signal is stored in the ST SW. In step S1503, it is compared whether or not the rotational speed NE is larger than a reference rotational speed (for example, 500 rpm). If larger, the process proceeds to step S1504, and if not, the process ends. In step S1504, whether the key state is the starter OFF state is determined based on the value of STSW. If the starter is OFF, the process proceeds to step S1505, and if not, the process ends. In step S1505, voltage waveform processing is performed. Here, the average and variance of the voltage during the alternator operation are calculated. In step S1506, it is determined whether or not the voltage waveform during the alternator operation is a predetermined pattern. If the voltage waveform is a predetermined pattern, the process proceeds to step S1507; otherwise, the process proceeds to step S1508. In step S1507, alternator normal processing is performed, for example, a flag is set that the alternator diagnosis has been completed. In step S1108, alternator abnormality processing is performed. For example, an alternator abnormality flag is set, and a warning lamp is turned on and a warning message is presented by sound or image.

  FIG. 16 is an example of a time chart when the alternator is normal. After the starter SW is turned off, the rotational speed is increased by the combustion energy of the internal combustion engine, and power generation by the alternator starts. The average voltage when the alternator is in operation is higher than the battery voltage at the start, and power is supplied to each device and the battery is charged.

  FIG. 17 is an example of a time chart when the alternator is abnormal. If the power generation efficiency of the alternator decreases, the voltage will not increase even if the rotational speed increases, or the voltage fluctuation will increase. Therefore, when the average voltage is not substantially different from the starting voltage, it is determined that the alternator is abnormal, and the alternator abnormality flag is set.

  FIG. 18 shows the relationship between the average voltage and the alternator abnormality in dispersion. When the average voltage is high compared to the normal state, it is an abnormality of the regulator attached to the alternator. When the dispersion is large or the average voltage is low, there is a possibility of an electric load abnormality. If there is no correlation, it can be determined that the electrical load is abnormal.

  Next, an embodiment of the internal combustion engine diagnosis according to the present invention will be described with reference to FIGS. According to this embodiment, an abnormality of the internal combustion engine can be easily detected based on the switch information, the rotational speed, the voltage, and the control parameter.

FIG. 19 is an example of a flowchart of the internal combustion engine diagnosis in the present invention. For example, the ECU is executed at intervals of 10 ms in the ECU. In step S1901, sensor input processing is performed, and the battery voltage is stored in VB and the rotation speed is stored in NE. In step S1902, switch input processing is performed. For example, the starter SW signal is stored in the ST SW. In step S1903, combustion at start-up is controlled by control processing by ignition (ADV), injection pulse width (TIM), throttle opening (TVO), and the like. In step S1904, it is compared whether or not the rotational speed NE is larger than a reference rotational speed (for example, 500 rpm). If larger, the process proceeds to step S1905. If not, the process is terminated. In step S1905, whether the key state is the starter OFF state is determined based on the value of STSW. If the starter is OFF, the process proceeds to step S1906, and if not, the process ends. In step S1906, control waveform processing is performed. Here, pattern matching of control parameters at engine start is performed. As a pattern matching method, a threshold value may be simply provided, or matching using a plurality of parameters may be performed by a neural network, an MT method, or the like. In step S1907, it is determined whether or not the control waveform at the start is a predetermined pattern. If it is a predetermined pattern, the process proceeds to step S1908; otherwise, the process proceeds to step S1909. In step S1908, normal processing of the internal combustion engine is performed, for example, a flag is set that the internal combustion engine diagnosis has ended. In step S1909, an internal combustion engine abnormality process is performed. For example, an internal combustion engine abnormality flag is set, and a warning lamp is turned on and a warning message is presented by sound or image.

  FIG. 20 is an example of a time chart when the internal combustion engine is normal. After the starter SW is turned off, the engine is operated in a predetermined start mode for a predetermined time, and then the FB control of the idle speed is started.

  FIG. 21 is an example of a time chart when the internal combustion engine is abnormal. If the combustion of the internal combustion engine is abnormal while the idling engine speed FB control is operating, the fuel quantity is increased or the throttle is opened to prevent the engine speed from decreasing. An abnormality of the internal combustion engine is detected by a control parameter pattern different from that in the normal state, and an abnormality flag of the internal combustion engine is set.

Schematic showing one Embodiment of this invention. An example of startability diagnosis by battery voltage. An example of startability diagnosis based on crank rotation speed. The flowchart example of a relay diagnosis. A time chart example when the relay is normal. A time chart example when the relay is abnormal. The flowchart example of a battery diagnosis. The time chart example when a battery is normal. An example of a time chart when the battery is abnormal. An example of determination MAP for battery diagnosis using history. The example of a flowchart of starter diagnosis. A time chart example when the starter is normal. A time chart example when the starter is abnormal. Example of determination MAP of starter abnormality. The flowchart example of an alternator diagnosis. An example of a time chart when the alternator is normal. Time chart example when the alternator is abnormal. Alternator abnormality determination MAP example. The flowchart example of an internal combustion engine diagnosis. The time chart example when an internal combustion engine is normal. An example of a time chart when the internal combustion engine is abnormal. An example of a correlation used to evaluate starting performance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... ECU, 2 ... Battery, 3 ... Internal combustion engine, 4 ... Starter, 5 ... Alternator, 101 ... Startability diagnostic means, 102 ... Sensor input means, 103 ... SW input means, 104 ... Control means.

Claims (8)

In an internal combustion engine diagnostic apparatus comprising a generator, a battery, and a starting device,
Sensor input means for processing the crank speed and battery voltage of the internal combustion engine;
Control means for controlling the starting state of the internal combustion engine;
Switch signal means for processing a key switch signal for controlling at least one of an electric system of a vehicle and the starter; and
The output signal output from the sensor input means, the control means, and the switch signal means is used, and the electrical system diagnosis is performed based on the output from the switch signal means, and the output signal from the sensor input means and the A diagnostic device for an internal combustion engine, comprising: diagnostic means for diagnosing start performance or startability of the internal combustion engine based on correlation of output signals from the control means. In an internal combustion engine diagnostic apparatus comprising a generator, a battery, and a starting device,
Means for detecting the rotational speed of the internal combustion engine; means for detecting the battery voltage;
Switch signal means for processing a key switch signal for controlling an energization state of at least one of an electric system of the vehicle and a starter; and
Means for detecting the control state of the internal combustion engine or the drive state or drive signal of the actuator, and the change characteristic of the battery voltage from the key switch signal ON state to the complete explosion to the first idle of the internal combustion engine or the internal combustion engine And a diagnostic means for diagnosing a part corresponding to the detection means at a predetermined timing for each diagnostic item after the key switch is turned on. A diagnostic device for an internal combustion engine.   2. The internal combustion engine according to claim 1, wherein at least one of a generator, a starter, a battery, an internal combustion engine, and a relay is diagnosed based on the output of the switch signal means in order to diagnose the starting performance of the internal combustion engine. Institutional diagnostic equipment.   4. The diagnostic apparatus for an internal combustion engine according to claim 3, wherein abnormality of the battery is diagnosed based on the battery voltage and a crank rotational speed of the internal combustion engine.   4. The diagnostic apparatus for an internal combustion engine according to claim 3, wherein an abnormality of the starter is diagnosed based on the battery voltage and the crank rotation speed when the starter is operating.   4. The diagnostic apparatus for an internal combustion engine according to claim 3, wherein an abnormality of the generator is diagnosed based on the battery voltage and the crank rotational speed after the starter is activated and stopped.   4. The internal combustion engine according to claim 3, wherein an abnormality of the internal combustion engine is diagnosed based on the battery voltage, the crank rotation speed, and the parameters of the control processing unit while the starter operates and stops. Diagnostic device. 4. The diagnostic apparatus for an internal combustion engine according to claim 3, wherein an abnormality of a relay driven by the key switch is diagnosed based on a battery voltage immediately before the starter operates.

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