JPH08284766A - Failure diagnosis device for port heater - Google Patents

Abstract

PURPOSE: To accurately detect the failure of a port heater by, in a fuel injection engine provided with the port heater which is arranged at a position where the fuel jetted from an injector can attain, and heatedly atomizes the fuel, comparing electrical characteristic at the start with actual electrical value. CONSTITUTION: At the time of starting an engine, specified fuel is jetted into an intake path 12 by an injector 13, and sucked into each cylinder together with air to produce fuel-air mixture, which is ignited and burned. In addition, heater current is supplied to a port heater 21 provided at a position attained by the jetted fuel through an electric supply means C2, and the jetted fuel is heated by the heater heat to quicken its atomization. In this case, at the time of starting the engine, the electrical value of the port heater circuit is detected by an electrical value detecting means C4, and the electrical characteristic at the normal time when the current is supplied to the port heator is compared with actual electrical value by a failure judging means C5 to judge the existence of the failure of the portheater 21, and when the failure is judged, an alarm is issued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a port heater failure diagnosing device for heating and atomizing fuel injected from an injector in a vehicle fuel injection engine. More specifically, the invention relates to port heater failure detection and port heater failure detection. The present invention relates to fuel injection correction control.

[0002]

2. Description of the Related Art In a multi-point type fuel injection engine, an injector is attached to each intake port of each cylinder of the engine. The electronic control system calculates the fuel injection amount by taking into consideration various factors such as the engine operating state, and the injector injects appropriate fuel into the intake port, and air is taken into the cylinder during the intake stroke by opening the intake valve. At the same time, the injected fuel is introduced together to generate an air-fuel mixture, which ensures good engine operation and reduces fuel consumption and exhaust emissions. By the way, even in this type of engine, when the engine body is cold at the time of starting the engine and the outside air temperature is low, the fuel injected by the injector becomes droplets and the atomization thereof deteriorates. Therefore, as a countermeasure for this, generally, the fuel is increased and corrected at the time of starting to secure the startability, but it is pointed out that the fuel consumption and exhaust emission at the time of starting are bad due to a rich mixture due to the increased correction. There is.

Therefore, as a measure for promoting fuel atomization at the time of engine start, for example, Japanese Patent Laid-Open No. 3-23364 proposes to use a port heater. In the intake port of the engine body, the port heater is arranged at a position where the fuel injected from the injector reaches. This port heater has a characteristic that its resistance is low when the temperature is low and that it increases when the temperature is high.The pill of the heating element is covered with an aluminum heat sink, and it is integrally bonded with an adhesive with good heat conduction. Configured. When the engine is cold started, the port heater is energized by the battery power, and a large amount of current flows through the port heater initially to generate heat. The heater heat directly heats the fuel that is injected from the injector and collides with the port heater. It is designed to promote

Since the port heater is heated by the battery power source each time the engine is started, there is a possibility that the port heater may be broken, peeled, deteriorated, or otherwise damaged when used for a long period of time. For this reason, it is desirable to detect the presence or absence of a failure appropriately and urge the user to perform repair, replacement, or the like. Further, in the fuel injection control system using the port heater, it is possible to reduce the increase correction at the start according to the promotion of fuel atomization, but it is necessary to take measures to ensure the startability when the port heater fails. is there. In this case, although it cannot generate heat due to disconnection, it can be used as a heater although the temperature rise characteristics deteriorate due to peeling or deterioration. Therefore, as a countermeasure against failure, it is desirable to detect disconnection and peeling separately and to take countermeasures suitable for the failure state.

Conventionally, regarding the above-mentioned heater failure detection of the engine, there is a prior art of Japanese Utility Model Laid-Open No. 62-12741, for example, in the preheating means for preheating intake air, the battery voltage when the engine key is turned on, and the relay for preheating means. It is shown that the disconnection alarm is issued by comparing with the battery voltage after a predetermined time from the excitation of. Further, as a countermeasure at the time of detecting a failure, there is a prior art disclosed in, for example, Japanese Patent Laid-Open No. 59-82563. It has been shown to ensure startability.

[0006]

By the way, the former of the prior art relating to the detection of a heater failure (Actual No. 62-1274).
No. 1) compares the battery voltage after a certain time, it is difficult to distinguish between disconnection and peeling in the case of a heater failure. The latter (Japanese Unexamined Patent Publication No. 59-82563) has a problem that the fuel injection amount of the injector cannot be corrected because the heater applied voltage is controlled when a failure occurs.

In view of the above points, the present invention aims to accurately detect a failure of a port heater that heats and atomizes the fuel injected from an injector, and to appropriately perform fuel injection correction according to the failure state. And

[0008]

In order to achieve this object, a port heater failure diagnosing device according to claim 1 of the present invention, as shown in FIG. 1, is an injector mounted in an engine intake passage 12 for injecting fuel. 13, a port heater 21 arranged at a position where the fuel injected from the injector 13 reaches to heat and atomize the fuel, a start detection means C1 for detecting engine start by an ignition switch signal, and a port by a battery power supply at the time of start. In the fuel injection engine provided with the energizing means C2 for supplying the heater current to the heater 21, the characteristic storing means C3 for preliminarily storing the normal electrical characteristics when the port heater is energized.
And an electric value detecting means C4 for detecting an actual electric value of the circuit of the port heater 21 at the time of starting, and an electric characteristic stored in the characteristic storing means at the time of starting and an actual electric value are compared to compare the port heater 21. And a failure determination means C5 for issuing an alarm when the failure is determined.

As shown in FIG. 2, the port heater failure diagnosing device according to a second aspect of the present invention calculates an injector 13 mounted in an engine intake passage 12 for injecting fuel and a fuel injection amount according to an engine state and an operating state. Then, the fuel injection control means C6 for outputting the injection signal to the injector 13
And a port heater 21 arranged at a position where the fuel injected from the injector 13 reaches to heat and atomize the fuel.
In the fuel injection engine including the start detection means C1 for detecting the engine start by the ignition switch signal and the energization means C2 for supplying the heater current to the port heater 21 by the battery power at the time of starting, when the port heater is energized, Characteristic storage means C3 for preliminarily storing electric characteristics at the time of normal operation, electric value detection means C4 for detecting an actual electric value of the circuit of the port heater 21 at the time of starting, and electric values stored in the characteristic storage means at the time of starting. The characteristics and the actual electrical value are compared to determine the presence / absence of a failure of the port heater 21, the failure state of peeling, deterioration, and disconnection, and a failure determination means C5 that issues an alarm when the failure determination is made, and a normal determination of the port heater 21. In this case, the fuel injection amount increase correction is reduced, and in the case of a failure, the fuel injection amount is increased successively according to the judgment of separation, deterioration, or disconnection. Characterized in that it comprises a correction means C7 corrected.

A port heater failure diagnosis apparatus according to a third aspect of the present invention, as shown in FIG. 3, has a multi-cylinder intake passage 1 for an engine.
, And a plurality of injectors 13a, 13b, ..., which are respectively attached to the fuel injectors 2a, 12b ,. , 13b, ...
, And a plurality of port heaters 21a, 21b, ... Which are arranged at positions where the injected fuel from the injectors 13a, 13b ,. And a start detection means C1 for detecting engine start by an ignition switch signal.
In a multi-cylinder fuel injection engine including a power supply means C2 for supplying a heater current to a plurality of port heaters 21a, 21b, ... Characteristic storage means C3 for storing electric characteristics in advance, electric value detection means C4 for detecting an actual electric value of the circuit of the port heaters 21a, 21b, ... At the time of starting, and characteristic storage means C3 at the time of starting. Failure determination means C5 that compares the electrical characteristics with the actual electrical values to determine the presence / absence of a failure in the port heaters 21a, 21b, ...
And a defective cylinder discriminating means C8 for discriminating the cylinder of the defective port heater, and a correcting means C7 for increasing and correcting the fuel injection amount of the defective cylinder.

In the port heater failure diagnosing device according to a fourth aspect, the electrical characteristic stored in the characteristic storing means C3 and the actual electrical value of the port heater circuit are a current value or a battery voltage. .

[0012]

Therefore, according to the first aspect of the present invention, the predetermined fuel is injected into the intake passage 12 by the injector 13 when the engine is started, and this fuel is sucked into each cylinder together with the air to generate the air-fuel mixture. At this time, a heater current flows from the battery power source to the port heater 21 by the energizing means C2, and when the port heater 21 is normal, the fuel that heats rapidly and collides with the port heater 21 is heated to promote atomization. To be done. Therefore, the fuel and the air are mixed well, and the engine operates smoothly and smoothly even at the cold start.

When the engine is started, the electrical value detecting means C4 detects the actual electrical value of the circuit of the port heater 21, and the failure determining means C5 energizes the port heater. Electrical values are compared,
As a result, the presence / absence of a failure in the port heater 21 is accurately determined. Then, when a failure is determined, an alarm is issued to appropriately notify the user.

In the second aspect, a predetermined fuel is injected into the intake passage 12 by the injector 13 when the engine is started, and this fuel is sucked into each cylinder together with the air to generate the air-fuel mixture. At this time, a heater current flows from the battery power source to the port heater 21 by the energizing means C2, and when the port heater 21 is normal, the fuel that heats rapidly and collides with the port heater 21 is heated to promote atomization. To be done. Therefore, the fuel and the air are mixed well, and the engine operates smoothly and smoothly even at the cold start.

When the engine is started, the electric value detecting means C4 detects the actual electric value of the circuit of the port heater 21, and the failure judging means C5 supplies the port heater 21 with electricity. Are compared with each other, and the presence / absence of a failure of the port heater 21 and the failure state of peeling, deterioration, and disconnection are accurately determined. In the normal determination of the port heater 21, the correction means C7 corrects the increase in the fuel injection amount of the injector 13 to a small amount in accordance with the promotion of atomization of the fuel, thereby improving the fuel consumption and the exhaust emission. In addition, the user is appropriately notified by issuing an alarm when it is determined that the port heater has failed. At this time, when it can be used as a heater due to peeling or deterioration, the fuel injection amount is slightly increased by the correction means C7 as compared with the normal state, so that the fuel consumption is reduced and the startability is secured. In the case of disconnection, as in the case where the port heater is not used, the amount of fuel injection is corrected by the correction unit C7 to be increased more than when it is separated or deteriorated, whereby ignition and combustion with a rich air-fuel mixture is performed to ensure startability. .

According to the third aspect of the present invention, when the engine is started, a plurality of injectors 13a, 13b, ... Inject predetermined fuel into the intake passages 12a, 12b ,. It is sucked into each cylinder to generate a mixture. At this time, a plurality of port heaters 21a, 2 of the multi-cylinder are supplied from the battery power source by the energizing means C2.
The heater current flows to 1b, ..., The port heater 21a,
.. are normal, the heat generated by the heaters rapidly heats the fuel colliding with the port heaters 21a, 21b ,. Therefore, the fuel and the air are mixed well, and the engine operates smoothly and smoothly even at the cold start.

When the engine is started, the electric value detecting means C4 detects the actual electric value of the circuit of the port heaters 21a, 21b, ... And failure determination means C5
Then, for example, the electrical characteristics in a normal state when the port heater is energized and the actual electrical value are respectively compared, and thereby the presence or absence of the failure of the port heaters 21a, 21b, ... Is accurately determined. At this time, the user is appropriately notified by issuing an alarm when a failure determination is made. Also, the failure determination means C
In step 8, the cylinder of the failed port heater is determined based on the failure determination result, and the correction unit C7 increases and corrects only the fuel injection amount of the failed cylinder. For this reason, the cylinder with the failed port heater has a rich air-fuel mixture, and the ignition and combustion properties are secured, so that the fuel efficiency and the startability are improved.

In the fourth aspect, the port heater 21 has a characteristic that the resistance is small and a large amount of current flows when the temperature is low, and the resistance is large and the current decreases when the temperature is high. Based on the current characteristics and the actual current value of the port heater 21, whether or not there is a failure in the port heater 21 is directly determined. Further, since the battery voltage drops according to the change in the current of the port heater 21, the presence or absence of a failure of the port heater 21 is determined by the battery voltage characteristic and the actual battery voltage.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The overall configuration of the multi-point fuel injection engine will be described with reference to FIG. Reference numeral 1 denotes an engine body, a piston 3 is inserted into a cylinder 2 of each cylinder of the engine body 1, an intake port 6 having an intake valve 5 is provided in a combustion chamber 4 at the top of the cylinder 2, and an exhaust gas having an exhaust valve 7 is provided. A port 8 is provided. As an intake system, air cleaner 9
Is communicated with a surge tank 11 via a throttle valve 10, the surge tank 11 is communicated with an intake port 6 of each cylinder via an intake passage 12, and an injector 13 for injecting fuel is attached to an inlet of the intake port 6, and A fuel atomizer 20 is provided. Further, a catalyst 15 is provided in the exhaust passage 14 from the exhaust port 8.

In the fuel atomizer 20, the port heater 21 is arranged at the position where the fuel of the injector 13 reaches the intake port 6. The port heater 21 has a characteristic that the resistance is low when the temperature is low and increases when the temperature is high. The pill of the heating element is covered with an aluminum heat sink and integrally bonded with an adhesive having good heat conduction. Configured. An electronic control unit (ECU) 40 is connected to control the heater current supplied to the port heater 21. Further, as the failure diagnosis device 22 for the port heater 21,
An ammeter 24 for detecting the heater current I is connected to the circuit 23 of the port heater 21.

Explaining the electronic control system, a crank angle sensor 30 for detecting the engine speed N, an air flow meter 31 for detecting the intake air amount Q, an O2 sensor 32 for judging the air-fuel ratio, and a water temperature sensor 33 for detecting the water temperature Tw. And so on. As shown in FIG. 5, the electronic control unit 40 has a ROM 41, a RAM 42, a CPU 43, a timer 44, an input port 45, and an output port 46, and the battery 34 is connected to the electronic control unit 40 via an ignition switch 35.
Connect to. When the engine is started, the ignition switch 35 is turned on to operate the electronic control unit 40, and the heater current I of the ammeter 24 and the signals of the sensors 30 to 33 are A / D converted by the converter 47, and the crank angle sensor 30 is operated. The signal from is input after being waveform-shaped by the waveform shaping circuit 48, and the injection signal is injected by the drive circuit 49 into the injector 13.
The heater current I is supplied to the port heater 21. Further, when the failure of the port heater 21 is determined, the alarm device 25 is configured to issue an alarm.

The electronic control unit 40 has a fuel injection system, a failure diagnosis system, and a fuel injection correction system as functions related to the present invention. The fuel injection system has an engine speed N and an intake air amount Q.
, The basic injection amount Tp, the air-fuel ratio feedback coefficient α,
The fuel injection amount Ti is calculated as follows based on the cold start coefficient Kst of the correction coefficient K at the start, the water temperature increase coefficient Ktw, the post-start increase coefficient Kas, the cylinder correction coefficient Kc, and the like. Ti = Tp · α {Kst (1 + Ktw + Kas + ・
.)} Kc Then, this injection signal is output to the injector 13 so that the fuel injected from the injector 13 is supplied to the engine state,
Properly control according to operating conditions. Further, when the engine is started, the correction coefficient K (Kst, Ktw, Kas) is changed according to the warm-up state, so that the fuel injection amount Ti of the injector 13 can be arbitrarily increased and corrected.

The failure diagnosis system obtains the current characteristic at the time of engine starting in advance by experiments or the like. This current characteristic is, for example, as shown in FIG. That is, when the port heater 21 is normal, the resistance is small at the initial low temperature and the current rapidly increases with the passage of time. When the peak current reaches a high temperature of 140 degrees, for example, the resistance increases and the current increases. Is a characteristic Is that gradually changes. On the other hand, when the port heater 21 is disconnected, the characteristic Io is shown in which the current becomes substantially zero. When the pill is separated from the heat sink by the port heater 21, current easily flows through the pill and its temperature rises quickly, so that the peak current becomes high and the time to reach the peak current is very short, which is characteristic Ih.

Even in the normal case, the difference in the individual heaters,
Since there are some variations in the actual current characteristics due to aging and the like, the current characteristic Is is provided with an upper limit value Im and a lower limit value In to set a predetermined determination width. The current characteristic Is in the normal case and the lower limit values Im and In are stored in the ROM, and the presence or absence of a failure and the failure state can be detected by comparing with the actual state of the heater current I. It will be possible.

Next, whether or not there is a failure in the port heater 21,
A fuel injection correction system for a failure state will be described. In a normal case, the fuel injection amount can be reduced by promoting the fuel atomization by the port heater 21. Therefore, in the above formula of the fuel injection amount Ti, the correction coefficient K (K
st, Ktw, Kas) is set to a small value. Further, in the case of disconnection at the time of failure, the correction coefficient K is set to a large value as in the case where the port heater is not used, and in the case of peeling or deterioration, the correction coefficient K can be used as a heater although the temperature rise characteristic deteriorates. Correct K to a value with a smaller increase rate than in the case of disconnection. As a result, it is possible to improve fuel efficiency and exhaust emission when the heater is normal, and to secure startability when the heater fails.

Further, a fault diagnosis for a plurality of cylinders and a plurality of port heaters arranged in each cylinder will be described.
For example, a case of four cylinders will be described. As shown in FIG. 7A, four port heaters 21a of the first to fourth cylinders are provided.
To 21d are connected in parallel and each port heater 21a to 21d is connected.
Ammeters 24a to 24d are connected to the four ammeters 24a
The heater currents Ia to Id of .about.24d are input to the electronic control unit 40, and the failure is detected for each of the port heaters 21a to 21d in the same manner as described above. In this case, the failed cylinder can be easily discriminated, and therefore, only the fuel injection from the injector of the failed cylinder among the four injectors 13a to 13d is corrected by, for example, the cylinder correction coefficient Kc.

Further, as shown in FIG. 4B, four port heaters 21a to 21d are connected in parallel and the heater current I is detected by one ammeter 24. Therefore, the heater current I of one ammeter 24 is input to the electronic control unit 40, and the failure diagnosis is performed based on the state of the entire heater current I. In this case, since it is difficult to determine the failed cylinder, all the injectors 13a to 13 of the four cylinders, for example, in order to ensure startability at the time of failure, are difficult to determine.
It is configured to correct the fuel injection of d.

Next, as a first embodiment of the present invention, basic fault detection and fuel injection correction control will be described with reference to the flow chart of FIG. First, in step S1, the operation state of the ignition switch 35 is checked, and when the engine is started from OFF to ON, the process proceeds to step S2 to initialize the fuel injection amount Ti. Further, in step S3, the heater current I is supplied to the port heater 21 from the battery power source,
A timer is set in step S4. Then step S5
In step S6, the heater current I (t) detected by the ammeter 24 at every predetermined time is input.
(T) is compared with the upper and lower limit values Im and In of the normal current characteristic Is stored in advance.

Therefore, the heater current I (t) becomes the current characteristic Is.
If the value of the fuel injection amount changes normally along with the upper limit value and falls between the lower limit values Im and In, the process proceeds to step S7 to make a normal determination, and in step S8, the correction coefficient K for the fuel injection amount at the start is set to a small value. Then, in step S9, the fuel injection amount Ti is calculated based on the correction coefficient K. Thereafter, in step S10, the heater preheating completion time Ts is checked, and the process is repeated until the completion time Ts is reached. When the completion time Ts is reached, the process proceeds to step S11, the timer is reset, the energization to the port heater 21 is cut off, and the process ends.

Therefore, when the engine is started, the port heater 2
When 1 is normal, when the initial temperature is low, the resistance of the port heater 21 is small, so that a large amount of current flows and heat is quickly generated, and the heater heat causes the injector 13 to inject the fuel and collide with the port heater 21. The fuel is directly heated to promote atomization. Therefore, in the intake stroke, the fuel that has been atomized together with the air is sucked into the cylinder 2, and the air-fuel mixture that is well mixed with the air is generated in the cylinder 2 to start the engine smoothly and smoothly even when the engine is cold. To do. In this case, the fuel injection amount Ti is increased according to the promotion of fuel atomization.
However, a small correction coefficient K is used for the small amount increase correction, so that a good air-fuel mixture is obtained and fuel consumption and exhaust emission are improved.

On the other hand, if the detected heater current I (t) deviates from the upper limit value Im and the lower limit value In of the normal current characteristic Is not only at the beginning but also in the middle thereof, the process proceeds from step S6 to step S12 to determine a failure. , An alarm is issued in step S13. Accordingly, the failure of the port heater 21 is accurately detected, and the user is notified by the alarm. In this case, the correction coefficient K is corrected to a large value in step S14,
In step S9, the fuel injection amount T is calculated based on the correction coefficient K.
i is calculated. Therefore, when the amount of fuel injected from the injector 13 is corrected when the engine is started and the fuel heating cannot be expected due to the disconnection, the startability is ensured.

As a second embodiment of the present invention, control of failure determination and fuel injection correction will be described with reference to the flowchart of FIG. In this embodiment, the difference from FIG. 8 will be described. In step S6, the heater current I (t) changes with the current characteristic Is.
If it is determined that the port heater 21 is out of the upper and lower limit values Im and In, the process proceeds to step S21, where the heater current I (t) is compared with the high peak current Imax in the case of separation, and I (t)> Imax. If it is even once, the peeling determination is made in step S22. Also, the heater current I (t)
Is I (t) ≦ Imax, it is determined whether or not there is zero when the wire breaks in step S23. If I (t) = 0, the wire break is determined in step S24, and I (t) ≠ 0. In any of the current reduction states, the deterioration is determined in step S25.
Thus, when the port heater 21 fails, the heater current I
According to the state of (t), the failure state of peeling, disconnection, and deterioration can be distinguished and accurately determined.

Although the temperature rising characteristic is deteriorated due to peeling or deterioration, in a state where the heater can be used as a heater, step S26 is performed.
Then, the correction coefficient K is set to an intermediate value between the normal state and the disconnection state, an alarm is issued in step S28, and the fuel injection amount Ti is calculated based on this in step S9. Therefore, when the engine is started, the fuel injected from the injector 13 is
The port heater 21 is atomized according to the lowered temperature rising characteristic. In addition, the amount of fuel is increased according to the deterioration of atomization performance,
As a result, startability is ensured while suppressing deterioration of fuel efficiency and the like.

If heat cannot be generated due to the disconnection, step S
27, the correction coefficient K is set to a large value, and step S
Similarly, at 28, an alarm is issued, and at step S9, the fuel injection amount Ti is calculated based on this. Therefore, the fuel injected from the injector 13 when the engine is started is sufficiently increased and corrected in the same manner as in the case where the port heater is not used, and the rich air-fuel mixture is reliably ignited and burned to ensure startability.

As a third embodiment of the present invention, control of failure detection and fuel injection correction in the case of individually detecting the heater currents of four port heaters in four cylinders will be described with reference to the flowchart of FIG. Explaining the points different from FIG. 8, the four port heaters 21a to 21a
The heater current I is made to flow to 21d by the battery power source, and four heater currents Ia detected in step S5 are obtained.
Input (t) to Id (t). After that, in step S31, the heater current Ia of the first cylinder is set every predetermined time.
It is determined whether or not the upper limit of the lower limit values Im and In is within the upper limit of the normal current characteristic Is in which (t) is stored in advance. If it is normal within the lower limit, the process proceeds to step S32 and the second cylinder Similarly, the heater current Ib (t) is determined. Hereinafter, the heater current Ic (t) of the third cylinder is determined in step S33, and the heater current Id (t) of the fourth cylinder is determined in step S34.
If all are normal, a normal judgment is made in step S7.

On the other hand, if the heater current I (t) deviates from the judgment range in any of steps S31 to S34, the process proceeds to step S12, a failure judgment is made, and an alarm is issued in step S13. As a result, when the engine is started, it is possible to accurately detect whether or not the four port heaters 21a to 21d of the four cylinders are out of order. In this case, in step S14, the correction coefficient K is set to medium or large similarly to FIG. 9 depending on the failure state, and the fuel injection amount Ti is calculated based on this in step S9, whereby the startability is ensured.

As a fourth embodiment of the present invention, the control in which the defective cylinder is further discriminated in the embodiment of FIG. 10 will be described with reference to the flowchart of FIG. Explaining the points different from FIG. 10, the four heater currents Ia (t) are calculated in step S5.
To Id (t), and then step S41
Check the first cylinder detection flag F1 with F1 =
0, the process proceeds to step S31, and the heater current Ia (t) of the first cylinder is set to the upper and lower limit values Im, I of the normal current characteristic Is.
If the port heater 21a is normal compared to n, step S
In step 45, the correction coefficient K is set to a small value, and in the case of a failure, the process proceeds to step S46 to issue an alarm, and as shown in FIG. 9, the failure is determined and the correction coefficient K is set according to the failure state. Then, in step S47, the fuel injection amount Tai of the first cylinder when the port heater 21 is normal or malfunctions is calculated, and then the flag F1 is set to F1 = 1 in step S48.

For the second time, step S is performed by the flag F1 = 1.
In step 42, the second cylinder detection flag is checked for F2. First, in step S32 with F2 = 0, the heater current Ib (t) of the second cylinder is set to the upper and lower limit values Im, In of the normal current characteristic Is. In comparison, the correction coefficient K is determined in step S49 or 50 depending on whether the port heater 21b is normal or faulty. Then, in step S51, the fuel injection amount Tbi of the second cylinder in the case of normal or failure is calculated, and then the flag F2 is set to F2 = 1 in step S52.

For the third time, step S is performed by the flag F2 = 1.
In step S43, the third cylinder detection flag F3 is checked. First, in step S33, when F3 = 0, the heater current Ic (t) of the third cylinder is set to the upper and lower limit values Im, In of the normal current characteristic Is. In comparison, the correction coefficient K is determined in step S53 or 54 depending on whether the port heater 21c is normal or faulty. Thereafter, in step S55, the fuel injection amount Tci of the second cylinder in the case of normal or failure is calculated, and then the flag F3 is set to F3 = 1 in step S56.

The fourth time is step S with the flag F3 = 1.
In step 44, the fourth cylinder detection flag F4 is checked. First, when F4 = 0, the process proceeds to step S34 in which the heater current Id (t) of the fourth cylinder is set to the upper and lower limit values Im and In of the normal current characteristic Is. In comparison, the correction coefficient K is determined in step S57 or 58 depending on whether the port heater 21d is normal or faulty. Thereafter, in step S59, the fuel injection amount Tdi of the fourth cylinder in the case of normal or failure is calculated, and then the flag F4 is set to F4 = 1 in step S60. After that, the process proceeds to step S61 with the flag F4 = 1, all the flags F1 to F4 are cleared, and the above control is repeated until the heater preheating completion time Ts is reached.

Therefore, when the engine is started, a failure and a failed cylinder in any of the four port heaters 21a to 21d are accurately detected by the four heater currents Ia (t) to Id (t) of the first to fourth cylinders. It Therefore, for example, when the port heaters 21a and 21c of the first cylinder and the third cylinder have a failure, it becomes possible to immediately know the failure location by the alarm of the cylinder. Further, only the fuel injection amounts Tai and Tci of the failed first and third cylinders are increased and corrected in accordance with the failed state, and ignition combustion is secured by the rich air-fuel mixture. Therefore, the startability is optimally secured while suppressing the deterioration of fuel efficiency and the like.

As a fifth embodiment of the present invention, for example, four port heaters are connected in parallel in four cylinders and one ammeter 2 is provided.
Control of failure detection and fuel injection correction when the entire heater current is detected in 4 will be described with reference to the flowchart of FIG. In this embodiment, four port heaters 21a-2
The sum of the heater currents Ia (t) to Id (t) flowing in 1d is the heater current I (t) detected by the ammeter 24. The heater current I (t) is equal to that of the four port heaters 21a to 2a.
In 1d, the flow varies according to the total resistance obtained by adding the resistance that changes momentarily, and there are many detection patterns when normal, peeled, and deteriorated ones are mixed. For this reason, the map of FIG. 6 when all the port heaters 21a to 21d are normal is synthesized, and there is nothing but detection of the presence or absence of a failure.

Explaining the points different from FIG. 8, the entire heater current I (t) is input in step S5, and then the process proceeds to step S71 to generate the heater current I (t).
Is zero, and if I (t) = 0, step S72 is performed.
At, the disconnection of all port heaters is judged and an alarm is issued, and at step S73, the correction coefficient K is set to a large value. I
When (t) ≠ 0, the process proceeds to step S74 and the heater current I
(T) is the combined value I of the upper and lower limits of the current characteristic Is under normal conditions.
If the heater current I (t) is within the judgment range as compared with m and In, the four port heaters 21a to
21d, it is determined that all of the normality is satisfied, and the correction coefficient K is set to a small value in step S76. If the heater current I (t) deviates from the judgment width, it is judged in step S77 that the four port heaters 21a to 21d have a failure in which normal, peeling, and deterioration are mixed, and an alarm is issued, and in step S78. The correction coefficient K is set to an intermediate value. Then, in step S9, 4
The fuel injection amount Ti of the first to fourth cylinders is uniformly calculated according to the presence / absence of a failure in each of the port heaters 21a to 21d.

Therefore, when the engine is started, the four port heaters 21a to 21d of the first to fourth cylinders are collectively detected to be in failure, and when all the port heaters 21a to 21d are normal, the fuel is reduced and the fuel consumption is improved. . In the case of a failure, it is detected whether all four port heaters 21a to 21d are in a failure state due to disconnection or a failure state in which normal, peeling, and deterioration are mixed, and the fuel amount is increased according to the two failure states. It is corrected, which ensures at least startability.

Referring to FIG. 13, as a sixth embodiment of the present invention, a case where voltage is used as the electrical characteristic of the port heater will be described. In this embodiment, the electronic control unit 4
The heater current I is connected to the port heater 21 from 0, the voltmeter 26 is connected to the battery 34 so as to detect the battery voltage V, and otherwise the configuration is the same as that of FIG. Then, the electronic control unit 40 sets the battery voltage V
To detect whether the port heater 21 is out of order,
When a failure is detected, the alarm device 25 gives an alarm.

Here, the battery voltage characteristic when the engine is started is as shown in FIG. That is, the port heater 2
When 1 is normal, the voltage drop is large due to the small resistance in the initial stage, and then the voltage Vs changes so that the voltage recovers as the resistance increases. On the other hand, when the port heater 21 is disconnected, the characteristic Vo has no voltage drop, and when peeling or deterioration occurs, the characteristic Vh has a small voltage drop. Therefore, also in this case, the predetermined determination range is set by providing the upper limit value Vm and the lower limit value Vn for the normal voltage characteristic Vs. Then, the voltage characteristic Vs in the normal case and the upper and lower limits Vm and Vn are stored in the ROM and compared with the actual state of the battery voltage V by the same control as that of the above-described embodiment, thereby determining the failure. It becomes possible to detect the presence / absence and the failure state. Further, by correcting the fuel of the injector 13 according to the presence / absence of a failure and the failure state as in the above-described embodiment, it is possible to improve fuel efficiency and ensure the startability.

Although the embodiment of the present invention has been described above, the fuel correction when the port heater fails is not limited to the embodiment.

[0048]

As described above, in the port heater failure diagnosis apparatus according to the first aspect of the present invention, in the fuel injection engine, the characteristic that prestores the normal electrical characteristic when the port heater is energized. The storage means, the electric value detection means for detecting the actual electric value of the circuit of the port heater at the time of starting, and the electric characteristic stored in the characteristic storage means at the time of starting are compared with the actual electric value to compare the electric value of the port heater. Since the configuration includes a failure determination unit that determines whether or not there is a failure and issues an alarm when the failure is determined, the failure of the port heater can be accurately detected. Further, in the case of a failure, an alarm can be appropriately notified to the user to prompt repair or replacement.

In the port heater failure diagnosing device according to the second aspect, in the fuel injection engine, the characteristic storing means for storing in advance the electric characteristics of the port heater when the port heater is energized, and the actual circuit of the port heater circuit at the time of starting. Of the port heater by comparing the electric value stored in the characteristic storing means at the time of start-up with the electric value detecting means for detecting the electric value of Failure determination means that determines the state and issues an alarm when a failure is determined, and increases the correction amount of the fuel injection amount in the normal determination of the port heater, and in the case of a failure, determines the fuel injection amount according to the determination of separation, deterioration, or disconnection. Therefore, the fuel consumption and the exhaust emission can be improved by the good mixture when the port heater is normal. Further, in the case of the failure of the port heater, the fuel mixture and the like can be improved and the startability can be secured by the air-fuel mixture whose amount is increased and corrected according to the failure state.

In the port heater failure diagnosis device according to the third aspect of the present invention, in a multi-cylinder fuel injection engine, characteristic storing means for storing in advance electric characteristics in a normal state when the port heater is energized, and a plurality of characteristic storing means at start-up are stored. The electrical value detecting means for detecting the actual electrical value of the circuit of the port heater is compared with the electrical characteristic stored in the characteristic storing means at the time of starting and the actual electrical value to determine whether the port heater has a failure. A plurality of failure determination means for issuing a warning when a failure is determined, a failure cylinder determination means for determining the cylinder of the failed port heater, and a correction means for increasing the fuel injection amount of the failure cylinder are provided. The failure of the port heater can be detected accurately. Further, by correcting the increase in the fuel injection amount of the defective cylinder, it is possible to secure the ignition and combustibility of the cylinder and suppress the fuel consumption.

In the port heater failure diagnosis apparatus according to the fourth aspect, the electric characteristic stored in the characteristic storage means and the actual electric value of the port heater circuit are current value or battery voltage. Failure can be accurately detected. In particular, in the case of the current value, it remarkably changes according to the resistance of the port heater, so that the detection accuracy becomes high, and it is advantageous that the failure of a plurality of port heaters can be determined.

[Brief description of drawings]

FIG. 1 is a first diagram of a port heater failure diagnosis device according to the present invention.
It is a claim correspondence diagram showing the configuration of the invention.

FIG. 2 is a second part of the port heater failure diagnosis device according to the present invention.
It is a claim correspondence diagram showing the configuration of the invention.

FIG. 3 is a third part of the port heater failure diagnosis device according to the present invention.
It is a claim correspondence diagram showing the configuration of the invention.

FIG. 4 is an explanatory diagram showing a configuration of an example of a fuel injection engine to which the present invention is applied and a failure detection control system by current.

FIG. 5 is a block diagram showing an electronic control unit.

FIG. 6 is a time chart showing an electric characteristic at a normal time and an actual electric value depending on an electric current.

FIG. 7 is a circuit diagram showing current detection states of a plurality of port heaters in the case of multiple cylinders.

FIG. 8 is a flowchart of port heater failure detection and fuel injection correction control according to the first embodiment.

FIG. 9 is a flowchart of port heater failure detection and fuel injection correction control according to the second embodiment.

FIG. 10 is a flowchart of port heater failure detection and fuel injection correction control according to the third embodiment.

FIG. 11 is a flowchart of port heater failure detection and fuel injection correction control according to the fourth embodiment.

FIG. 12 is a flowchart of port heater failure detection and fuel injection correction control according to the fifth embodiment.

FIG. 13 is an explanatory diagram showing a voltage failure detection control system.

FIG. 14 is a time chart showing electrical characteristics and actual electrical values under normal conditions depending on voltage.

[Explanation of symbols]

 12, 12a, 12b Intake passage 13, 13a, 13b Injector 21, 21a, 21b Port heater 23 Circuit C1 Starting detection means C2 Energization means C3 Characteristic storage means C4 Electric value detection means C5 Failure determination means C6 Fuel injection control means C7 Correction means C8 Defective cylinder identification means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 69/00 310 F02M 69/00 310T F02N 17/08 F02N 17/08 D F02M 31/12 301T

Claims (4)

[Claims] 1. An injector attached to an engine intake passage for injecting fuel, a port heater arranged at a position where fuel injected from the injector reaches to heat and atomize the fuel, and an engine start detected by an ignition switch signal. In a fuel injection engine having a start detection means for operating the port heater and an energization means for supplying a heater current to the port heater by a battery power source at the time of starting, a characteristic storage means for pre-storing the normal electrical characteristics when the port heater is energized And an electric value detecting means for detecting an actual electric value of the circuit of the port heater at the time of starting, and an electric characteristic stored in the characteristic storing means at the time of starting, and the actual electric value are compared to detect a failure of the port heater. A port heater failure diagnosis, comprising: a failure determination unit that determines presence / absence and issues an alarm when a failure determination is made. Apparatus. 2. An injector mounted in an engine intake passage for injecting fuel, fuel injection control means for calculating a fuel injection amount according to an engine state and an operating state and outputting an injection signal to the injector, and an injector from the injector. A port heater arranged at a position where the injected fuel reaches and heating and atomizing the fuel, a start detecting means for detecting engine start by an ignition switch signal, and an energizing means for supplying heater current to the port heater by a battery power at the time of start In a fuel injection engine including: a characteristic storage means for storing in advance electric characteristics when the port heater is energized, and an electric value detection means for detecting an actual electric value of a circuit of the port heater at the time of starting. And the electrical characteristics stored in the characteristic storage means at the time of starting and the actual electrical values are compared, Whether there is a failure, and the failure state of peeling, deterioration, and disconnection, and that issues a warning when the failure is determined, and the normal determination of the port heater reduces the fuel injection amount increase correction, and if there is a failure, A port heater failure diagnosis device comprising: a correction unit that sequentially corrects an increase in the fuel injection amount in accordance with a determination of separation, deterioration, or disconnection. 3. A plurality of injectors, each of which is attached to an intake passage of a multi-cylinder of an engine and injects fuel, and a fuel injection amount according to an engine state and an operating state is calculated to output injection signals to the plurality of injectors. Fuel injection control means for outputting, a plurality of port heaters arranged in a position where the fuel injected from the injector reaches each cylinder to heat and atomize the fuel, and start detection means for detecting engine start by an ignition switch signal In a multi-cylinder fuel injection engine having a power supply means for supplying a heater current to each of a plurality of port heaters by a battery power source at the time of starting, a normal electrical characteristic when the port heater is energized is stored in advance. Characteristic storage means, electric value detection means for detecting the actual electric value of the circuit of the port heater at the time of starting, and starting The electrical characteristic stored in the characteristic storage means is compared with the actual electrical value to determine whether or not there is a failure in the port heater, and when the failure is determined, the failure determination means that issues an alarm and the cylinder of the failed port heater are determined. A failure diagnosis device for a port heater, comprising: a malfunctioning cylinder determining unit that performs the above-described malfunctioning; and a correction unit that corrects an increase in the fuel injection amount of the malfunctioning cylinder. 4. The port heater failure diagnosis according to claim 1, wherein the electric characteristic stored in the characteristic storage means and the actual electric value of the port heater circuit are a current value or a battery voltage. apparatus.