JPS6248935A - Trouble discriminator for internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To aim at the protection of an engine, by installing a supercharger trouble detecting device detecting anything unusual in a supercharging state, and also a trouble signal generating device generating a trouble signal at the time of detecting an unusual state in a supercharger. CONSTITUTION:A supercharging state detecting device 3 generating a signal conformable to a factor showing a supercharging state, a first setting device 4 setting a first setting value to judge an unusual state in a supercharger 2 and a supercharger trouble detecting device 5 detecting anything unusual in the supercharging state are all installed in this device. A second setting device 6 setting such a supercharging state as being lighter than that of the first setting device 4 is installed as well. Also there is provided with a trouble signal generating device 7 which compares a signal out of the supercharging state detecting device 3 with a second setting value and generates a trouble signal when the unusual state of the supercharger is detected by the supercharger trouble detecting device 5. A signal conformable to the supercharging state is compared with the first setting value, and when it is judged as trouble, this fact is stored in memory in advance, then in comparison with the second setting value, trouble discrimination takes place. Therefore, until necessary measures are taken since the trouble has happened, such a fear that severe load is imposed on an engine is thus avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an abnormality determination device for a supercharged internal combustion engine.

[Conventional technology]

In an internal combustion engine with a supercharger such as a turbocharger, a bypass control valve is provided in a bypass passage that bypasses the supercharger, and the bypass control valve is driven to open and close depending on whether the boost pressure exceeds a predetermined value. The boost pressure is controlled so as not to exceed a predetermined value.

Therefore, if the bypass control valve becomes inoperable due to a failure, the boost pressure may become abnormally high.

Therefore, for fail-safe purposes, a sensor means is installed to detect abnormalities in the supercharging state, and when an abnormality in the supercharging state is detected, fuel is cut to prevent the supercharging pressure from increasing abnormally. It is being In this case, as a means for detecting an abnormality, the intake air amount-to-rotation speed ratio and supercharging pressure are detected, and when these exceed a predetermined level, it is determined that there is an abnormality and a fuel cut signal is generated. (For example, JP-A-57-2
See No. 006385. ) [Problems to be Solved by the Invention] In the conventional system, due to unavoidable tolerances of the sensor, the determination level for determining that the supercharging state is abnormal must be set quite high. That is, due to tolerances, the signal levels from sensors such as pressure sensors and air flow meters vary somewhat between products. Assuming that the output deviates to the higher level within the tolerance range, if the abnormality determination level is not relatively high, the normal state will be incorrectly determined as abnormal. In this way, the abnormality detection level is set to a high level (this means that if there is an abnormality, the driver can recognize the abnormality and immediately take measures such as repair. The time will be relatively extended, which is unfavorable for the engine.

Furthermore, if the abnormality determination level is set high, the abnormality determination level may not be exceeded in a high rotation range where the boost pressure or the intake air amount-supercharging pressure ratio decreases, making it impossible to detect the abnormality. That is, if the load shifts to high in the low rotation range and the rotation speed gradually increases, the abnormality can be detected in the middle rotation range because it exceeds the abnormality determination level.

However, when a high load occurs in a high rotation state, the abnormality determination level is not exceeded, so even though it is abnormal, it cannot be detected, which is undesirable for the engine.

The present invention has been made in order to eliminate such drawbacks of the prior art, and its purpose is to reliably detect engine abnormalities even if there are tolerances of sensors for determining abnormal conditions.

[Means and effects for solving the problem] FIG. 1A shows the first invention. In FIG. 1A, 1 is an internal combustion engine, and 2 is a supercharger.

The abnormality determination device of the present invention includes a supercharging state detection means 3 that generates a signal according to a factor representing a supercharging state, and a first setting that sets a first set value for determining an abnormal state of the supercharger 2. means 4, supercharger abnormality detection means 5 for detecting an abnormality in the supercharging state by comparing the signal from the supercharging state detection means 3 with a first setting value, and supercharging lighter than the first setting means 4. When an abnormal state of the supercharger is detected by the second setting means 6 for setting the state and the supercharger abnormality detecting means 5, the signal from the supercharging state detecting means 3 is compared with the second setting value. It consists of an abnormal signal generating means 7 that generates an abnormal signal.

As an embodiment, the supercharger abnormality detection means 5 is composed of a comparator 5a and a launch means 5b such as a flip-flop. Further, the abnormal signal generating means 7 can be configured by an AND circuit 7a and a comparator 7b.

The operation of this first invention is as follows. The supercharging state detection means 3 generates a signal according to the supercharging state, and an abnormal state is detected by comparing the signal with the level set by the first setting means 4. When the sensor level exceeds the first set value, comparator 5
A signal is output from a, and the latch 5b maintains this state. In this way, once an abnormality is detected, the second
The set level is compared by a comparison circuit 7b via an AND circuit 7a, and when this level is exceeded, an abnormality signal is generated by the abnormality signal generating means 7.

The second invention is shown in FIG. 1B. In Figure 1B, 1
is an internal combustion engine, and 2 is a supercharger. The fuel cut control device of the present invention includes a supercharging state detection means 3 that generates a signal according to a factor representing the supercharging state, and a first set value that sets a first set value for determining an abnormal state of the supercharger 2. a setting means 4; a supercharger abnormality detection means 5 for detecting an abnormality in the supercharging state by comparing the signal from the supercharging state detection means 3 with a first setting value; When an abnormal state of the supercharger is detected by the second setting means 6 for setting the charging state and the supercharger abnormality detecting means 5, the signal from the supercharging state detecting means 3 is compared with the second setting value. The fuel cut signal generating means 7 includes a fuel cut signal generating means 7 which generates a fuel cut signal according to the fuel cut signal generating means 7, and a fuel supply stopping means 8 which stops the fuel supply to the internal combustion engine in response to a signal from the fuel cut signal generating means 7.

As an embodiment, the supercharger abnormality detection means 5 is composed of a comparator 5a and a launch means 5b such as a flip-flop. Further, the fuel cut signal generating means 7 is an AND circuit 7a.
and a comparator 7b.

The operation of this second invention is as follows. The supercharging state detection means 3 generates a signal according to the supercharging state, and an abnormal state is detected by comparing the signal with the level set by the first setting means 4. When the sensor level exceeds the first set value, comparator 5
A signal is output from a, and the latch 5b maintains this state. In this way, once an abnormality is detected, the second
The set level is compared by a comparison circuit 7b via an AND circuit 7a, and when this level is exceeded, the fuel supply stop means 8 is driven and fuel cut is executed.

〔Example〕

In FIG. 2, 10 is a cylinder block, 12 is a piston, 14 is a connecting rod, 16 is a cylinder head, 18 is a combustion chamber, 20 is a spark plug, 22 is an intake valve, 2
4 is an intake port, 26 is an exhaust valve, and 28 is an exhaust boat. The intake boat 24 is connected to a surge tank 30, and a throttle valve 32 is located upstream thereof. Throttle valve 3
2 is connected to an air flow meter 40 via an intake pipe 34, 36 and an intake hose 38. A fuel injector 42 is located adjacent to the intake port 24 . exhaust boat 2
8 is connected to exhaust pipes 44 and 46. 48 is a distributor.

The turbocharger 50 consists of a compressor wheel 52 between the intake pipes 34 and 36 and a turbine wheel 54 between the exhaust pipes 44 and 46. The turbine wheel 54 is driven by exhaust gas and rotates the compressor wheel 52. There is a bypass passage 56 that bypasses the turbine wheel 54 and a bypass control valve (wastegate pulp) 58 is located. Bypass control valve 58 is connected to the diaphragm of diaphragm actuator 62 by linkage 60 . The diaphragm chamber is connected to the intake pipe 34 downstream of the compressor wheel 52 via the door pressure vibro 4 . When the boost pressure has not reached a predetermined value, the bypass control valve 58 is closed. The supercharging pressure is introduced into the actuator 62, and when it reaches a predetermined value, the bypass control valve 58 is opened via the link mechanism 60, opening the bypass passage 56 and controlling the supercharging pressure.

A control circuit 66 is provided for controlling the fuel injector 42 and is configured as a microcomputer system. The control circuit 66 includes a microprocessing unit (M
PU) 68, memory 70, input port door 2, output port door 4, and bus 76 connecting these.

Signals from each sensor are input to the input port door 2. Air flow meter 40 is connected to input port door 2,
A signal corresponding to the intake air IQ is input. The intake air temperature sensor 74 is provided near the air flow meter 40, is connected to the input port door 2, and inputs a signal THA corresponding to the temperature of intake air from the outside. Water temperature sensor 78
is installed at the water jacket of the cylinder block 10, connected to the input port door 2, and inputs a signal THW corresponding to the temperature of the engine cooling water. Crank angle sensors 80 and 82 are provided on the distributor 48 and connected to the input port door 2. The first crank angle sensor 80 cooperates with a first magnetic member 84 on the distributor shaft 48a, and generates a pulse signal G, for example, every 720° C., which becomes a reference signal. On the other hand, the second crank angle sensor 82 cooperates with a second magnetic member on the distributor shaft 84 and generates a pulse signal N every 30° C., for example, which is useful for determining the engine speed.

3 to 5 are flowcharts illustrating the operation of the first embodiment of the control circuit 66. Of course, the program that implements this flowchart is stored in the nonvolatile area of the memory 70. The contents of this flowchart will be explained below. FIG. 3 shows the main routine, and this routine is started when the power is turned on (the ignition switch is turned on). In step 90, the bypass control valve abnormality detection flag f1 is reset. This flag is normally "011", but becomes "111" when a supercharging state corresponding to an abnormality of the bypass control valve 58 occurs.

Step 92 typically shows other initialization processing that is executed when the power is turned on. Step 94 shows each process executed within the main routine, and is executed repeatedly.

FIG. 4 shows a fuel injection routine, and this routine begins execution when the crank angle sensors 80 and 82 detect a predetermined crank angle before the fuel injection timing.

In step 96, it is determined whether the fuel cut flag f=1. This flag f is set to 1° when the fuel is cut off, and is set to 0° when the fuel is supplied.

When the fuel supply condition is met, r=0, and the flow proceeds from step 96 to step 98, where basic injection ff1Tp is calculated as follows: Tp=(Q/N)xK. Here, K is a constant.

In step 100, the final injection amount TAU is determined as TAU=Tp
It is executed by Xα(1+β)+r. Here, α, β, and γ represent various correction coefficients and correction amounts, such as feedback correction, temperature correction, and acceleration correction.

In step 101, this calculated injection amount of 1 TAU is set to the output port door 4, and the fuel injector 42 is driven to inject that amount of fuel.

When the fuel cut condition is ``=1'', the flow proceeds from step 96 to step 102, where TAU is set to O.Therefore, fuel is cut.

FIG. 5 shows a fuel cut flag control routine, which is a time interrupt routine executed at predetermined time intervals (for example, every 50 msec). In step 110, it is determined whether the bypass control valve abnormality detection flag f1=1. As explained in FIG. 3, this flag is initialized so that r=0 when the power is turned on. Therefore, initially, the determination is NO, and the process proceeds to step 112, where it is determined whether the intake air amount to revolution speed ratio Q/N, which is the load equivalent value, exceeds the first abnormality determination level A1.

This level A1 is a value that can only be taken in abnormal situations (for example, Q/N = 1.8N/rev), including variations between products.
is set to That is, FIG. 6 shows the relationship between the engine speed and Q/N when the throttle valve 32 is fully open. Curve a shows the change characteristic (median value) of Q/N with respect to engine speed N when the bypass control valve 58 operates normally, and curve b shows the change characteristic of Q/N of the upper limit allowed as variation between products. . Curve C shows the change characteristic of Q/N during an abnormality when the bypass control valve 58 does not operate normally.

The first abnormality determination level A1 is the upper limit of variation (curve b)
The pressure is set to be higher than the pressure when the bypass control valve is abnormal, and lower than the pressure when the bypass control valve is abnormal (curve C) in most of the rotation speed range.

When the bypass control valve 58 is operating normally, Q/
Since N<Al, the determination is No, and the flag f1 is set to O.
maintain. The process flows from step 112 to step 114, and nl (for example, 6) is entered into the counter C1.

This counter C1 measures the number of times this routine is executed after the value of Q/N exceeds the first set value A1, as will be described later.

When the bypass control valve 58 becomes abnormal, the Q/N exceeds the first set value A1, so step 112 is changed to step 11.
6, the counter C1 is decremented.

Next, the process proceeds to step 118, where it is determined whether the value of the counter C1 is O or not. If C1 has not fallen to O, the branch is No, and therefore the flag r1 is still maintained at 0. This is to prevent a fuel cut immediately after the Q/N exceeds the abnormal setting value A1, and as a result, a fuel cut is not performed when the Q/N exceeds the abnormal value A1 due to noise. There is no such thing.

Even if this routine is executed for the n1th time after Q/N exceeds A1, this state still exists! ! (for example, n1
= 6 (if (6-1) x 50 msec - 0.25 seconds have elapsed), it is determined Yes in step 118,
Proceeding to step 120, the abnormality determination flag f1 is set to 1, and in step 122, the counter C2 is set to n2 (
For example, 6) can be entered. This counter C2 measures the number of times this routine is executed after Q/N exceeds the second set value.

When an abnormality in the bypass control valve 58 is detected in this way, r1=1, so the next time this routine is executed, the process proceeds from step 110 to step 124, and Q/N is greater than the second abnormality determination level A2. It is determined whether or not.

This second judgment level A2 is smaller than the first rubel A1, and is equivalent to the Q/
The value is set to H. If Q/N>A2, step 1
26, the counter C2 is decremented. In step 128, it is determined whether c2=o. Q/N>A2
If the routine has not been executed n2 times since , (that is, if C2 has not fallen to O), the process proceeds to step 130 and the fuel cut flag is reset. Therefore, in the routine of FIG. No fuel cuts will be made.

Therefore, even if Q/N is larger than the second set value A2,
After entering this state, fuel cut is not executed for a certain short period of time (0.25 seconds as described above if nz=6).

After that time has passed, C2=0, so step 1
The process proceeds from step 28 to step 130, where a fuel cut flag f is set. Therefore, fuel cut is performed by executing the routine shown in FIG.

In this way, when Q/N falls below the second set value A2 as a result of the fuel cut being executed, the determination at step 124 becomes Yes, and the process proceeds to step 132 where the counter C2
n3 (for example, 6) is inserted into the field. Therefore, Q/N=
Fuel supply and fuel cut will be repeated after A2.

The value n2 placed in counter C2 in step 122 may be less than the value n3 placed in counter C2 in step 134. For example, n2=1, n3=6°. In this case, when an abnormal state is entered, the abnormality flag f1 is set after a short waiting time (delay) and a fuel cut is executed, which is favorable for engine protection. However, once the abnormality flag r1 is set, the fuel cut is performed after a sufficient period of time (n3) has elapsed, thereby preventing frequent fuel cuts due to noise.

FIG. 7 shows a fuel cut flag control routine in the second embodiment. This routine differs from FIG. 5 in that steps 136-142 are added.

Since the other steps are the same, the same numbers are given to the same processes, and the explanation thereof will be omitted. In step 136, the water temperature T
It is determined whether W is greater than or equal to a predetermined value T1 (for example, 50°C), and in step 138, the air temperature THA is set to a predetermined value T2.
(for example, 0° C.) or higher. During low-temperature operation where the water temperature and intake air temperature do not satisfy the requirements, the air density becomes high and the Q/N becomes large, so fuel cut control is not performed to prevent erroneous determination. Further, in step 140, the engine rotation speed N is set to a predetermined value N1 (for example, 5000r
It is judged whether it is smaller than pm, and if it is larger, the judgment level is set to A11 (<A1, for example 1.61/r
ev) to keep the judgment level low. This is because the Q/N decreases as the rotation speed increases even when the bypass control valve is abnormal (see curve C in FIG. 6), so the criteria for determination is lowered accordingly.

According to this embodiment, once an abnormality is detected and the flag f1 is set, this is maintained as long as the power is turned on, and fuel is cut every time the Q/N exceeds the setting. Therefore, the driver can immediately notice the abnormality and take appropriate action.

Further, in the embodiment, abnormality is determined by detecting Q/N, but abnormality can also be detected by determining the supercharging state based on factors such as supercharging pressure.

The invention of this application does not necessarily need to be combined with a fuel cut (and can also be used independently as an abnormality determination device. In other words, after the predetermined load value exceeds the first large level once, this is considered to be an abnormal state. The most extensive concept of this invention is to memorize the abnormality signal and then determine the abnormality at a small second level.The abnormality signal stored in this way is not limited to fuel cut, but can also be used for example in the alarm system. It will be used for driving.

〔Effect of the invention〕

According to this invention, the factor of the supercharging state is detected at the first determination level, and if it is determined that the engine is abnormal, this is stored and abnormality determination is performed at the second determination level lower than the first determination level. Therefore, a severe load is not applied to the engine until necessary measures are taken after an abnormality occurs, and the engine can be protected.

Moreover, once a high load at low to medium speeds is experienced, even if the load changes from light to high at high rotation, an abnormality is detected because the load exceeds the second determination level. Therefore, engine protection can be achieved.

By combining this with fuel cut, once an abnormality exceeds the first judgment value, the fuel will be cut at the second judgment value, which is lower, and the engine will no longer produce output, so the driver will notice the engine abnormality quickly. This can prompt the patient to take necessary measures immediately.

[Brief explanation of the drawing]

FIG. 1A and FIG. 1B are diagrams showing the configuration of the present invention. FIG. 2 is an overall configuration diagram of the embodiment. 3 to 5 are flowcharts showing the operation of the control circuit. FIG. 6 is a graph explaining the invention in detail. FIG. 7 is a flowchart similar to FIG. 5 for explaining the fuel cut flag control routine in the second embodiment. 40... Air flow meter, 42... Fuel injector, 50... Turbocharger, 58... Bypass control valve, 62... Actuator, 66... Control circuit, 80.82... Crank angle sensor.

Claims (1)

[Scope of Claims] 1. Abnormality determination device for an internal combustion engine with a supercharger comprising the following components: A supercharging state detection means that generates a signal according to a factor representing the supercharging state; Abnormality of the supercharger a first setting means for setting a first set value for determining the state; a supercharger abnormality detection means for detecting an abnormality in the supercharging state by comparing a signal from the supercharging state detection means with the first set value; , a second setting means for setting a lighter supercharging state than the first setting means, and when an abnormal state of the supercharger is detected by the supercharger abnormality detecting means, the signal from the supercharging state detecting means and the second setting means are set. Abnormal signal generation means that compares set values and generates an abnormal signal. 2. A fuel cut control device for a supercharged internal combustion engine consisting of the following components: a supercharging state detection means that generates a signal according to a factor representing the supercharging state; a first setting means for setting the first setting value; a supercharger abnormality detection means for detecting an abnormality in the supercharging state by comparing a signal from the supercharging state detection means with the first setting value; a first setting means a second setting means for setting a lighter supercharging state; when the supercharger abnormality detection means detects an abnormal state of the supercharger, the signal from the supercharging state detection means is compared with the second set value; Fuel cut signal generation means for generating a fuel cut signal; and fuel supply stop means for stopping fuel supply to the internal combustion engine in response to a signal from the fuel cut signal generation means.