JPS5912867B2 - Inspection device for electronic fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection device for diagnosing whether an electronic fuel injection device installed in an automobile is operating normally or not in a short period of time while the device is installed.

Conventionally, functional diagnosis of an electronic fuel injection device installed in a car is performed by separating the main circuit of the electronic fuel injection device and the connection line including the sensor by removing the inlet connector of the electronic fuel injection device. Diagnosis of the main body circuit is performed by applying a pseudo load or pseudo signal from the outside and diagnosing the circuit based on the input/output relationship, and conducting a continuity test or voltage test from the outside through the connector on the connection wire to determine pass/fail. Ta.

However, the conventional method as described above has the following disadvantages.

In other words, (1) the main connector cannot be inspected unless the main circuit and the connection wire are separated, (2) it is impossible to test for poor contact in the main connector between the main circuit and the connection wire, and (3) the main connector must be connected twice for inspection. (4) Since the test connector must be connected and disconnected from the outside, one of the times is the connection and disconnection of the test connector from the outside, which accelerates the deterioration of the main connector. There were some inconveniences, such as not being able to clearly see the effects of other parts.

The present invention has been made with attention to these points, and eliminates the above-mentioned disadvantages by providing an inspection device that can determine the quality of the electronic fuel injection device in a short time (without disconnecting the line of the electronic fuel injection device installed). The purpose is to provide

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

In FIG. 1, the electronic fuel injection device 1 inputs information such as the intake air amount and water temperature corresponding to the throttle opening from the status sensors 2 to the main body circuit 4 via the connector A, and Information on operating conditions such as running and acceleration is also input from the operation command sensors 3 through the connector A, and the main body circuit 4 calculates the optimum injection amount at that time from this input information, and pulses the calculation result. The width is outputted via the connector B to drive the injection valve 5.

The fuel injection amount is proportional to the pulse width for driving the injection valve 5, and the pulse width tg can be expressed as follows.

However, K1 is a constant specific to the type of engine, 2 is a value given by the operating state (for example, warm-up), and takes a value of 1 to 2, n is the engine rotation speed, U is the intake air amount, and K3
is a constant.

Here, if the engine speed n and the intake air amount U are constant, it can be expressed as proviso, and the value of K2 will be a moderate value of 10 to 2.0.

For example, when the accelerator pedal is idling with little pressure or when driving at a constant speed, it becomes 2-1, when the accelerator pedal is depressed slightly, it becomes 2 = 1.5, and when the accelerator pedal is slightly depressed, it becomes 2 = 1.5, and when the accelerator pedal is slightly depressed, it becomes 2 = 1.5. Take 2=2.

That is, K2 takes an appropriate value between K2-1 and K2-2, and the pulse width tg changes depending on the value of K2, that is, the injection amount is generally increased.

The inspection device 6 of the present invention is for inspecting whether the above-described functions of the electronic fuel injection device 1 are operating normally. At the time of inspection, the inspection device 6 is connected to the electronic fuel injection device 1 through a check connector C. .

The detection circuit 8 monitors the input/output relationship of the main circuit 4 of the electronic fuel injection device 1, and the detection result is input to the judgment circuit 9, which determines the fuel injection amount calculated from the input information and the main circuit 4. It determines whether the difference with the actual injection valve drive signal that is being output is within the specified range or not, and also determines what state the electronic fuel injection device 1 is currently in and what operation should be performed next. The judgment is made and displayed to the inspector by the display circuit 10, which will be described later.

For example, in the case of an accelerated increase test, when the judgment circuit 9 judges through the detection circuit 8 that the warm-up has been sufficient and preparations for the test are complete, the judgment circuit 9 sends a message to the variable fixing circuit 7 to determine whether there is a possibility of a sudden change during measurement. A command is given to make the output of a certain intake air amount U constant, and the variable fixing circuit 7 fixes the output of the intake air amount U to a constant value.At the same time, the judgment circuit 9 displays, for example, a lamp display.
The character display requests the inspector to perform accelerator work during acceleration via the display circuit 10.

As a result, when the inspector depresses the accelerator, the main body circuit 4 increases the acceleration amount, eg, takes a value of 1.5 as 2 due to the operation of the operation command sensors 3, for example, a throttle valve switch to be described later.

During this time, the detection circuit 8 is observing the change, and the judgment circuit 9 calculates the difference in the injector drive pulse width before and after the inspector performed the accelerator work, and judges whether or not the fuel increase operation was performed normally. do.

That is, when the engine speed n and the intake air amount U are fixed by the command from the judgment circuit 9, the pulse width immediately before acceleration increase and the pulse width immediately after acceleration increase from equation (2) calculate 4 to ti = 0.5. , performs pass/fail judgment.

For example, it varies depending on the rotation speed and intake air amount.
-1, the acceleration increase ti becomes 0.5, but if the output from the main circuit 4 is not 0.5, either the pulse width immediately before the acceleration increase or the pulse width immediately after the acceleration increase is inappropriate. I understand.

Now, what has been described so far does not include the condition that the engine speed n is constant.

Even if the output of the intake air amount sensor is set to 1-, the engine speed will increase when the accelerator is depressed and the throttle valve switch (described later) is switched, but the change will be slight in the short period of time. can be,
In comparison, the increase in the injector drive pulse width responds quickly.

From this, it can be assumed that the engine speed n is constant during the period in which the difference is being detected.

Further, the intake air amount U is fixed constant as described above.

FIG. 2 is a flowchart showing the operation of the block diagram shown in FIG. 1, and FIG. 3 is a circuit diagram of an embodiment of the block diagram shown in FIG.

In FIG. 3, the main circuit 4 is the ignition coil 1.
1 negative terminal, water temperature sensor 12. ignition key 13
．． Throttle valve switch 14, intake air amount sensor 1
From the input signal of 5, determine the optimal pulse width (
injection amount) and outputs it.

The water temperature sensor 12 is a thermistor, and the throttle valve switch 14 is linked to the throttle valve.

As shown in the diagram, when the accelerator pedal is not depressed, it is connected to the idle state, and when it is depressed to a certain range, it is turned off, and when it is further depressed a certain amount (acceleration or high-speed driving).
fully connected.

The intake air amount sensor 15 is located between the air cleaner and the throttle valve, and is designed to extract a voltage that is inversely proportional to the amount of air passing through it.

Now, start the engine and move the ignition key 13 to the IG terminal position.

The judgment circuit 9 knows from the water temperature sensor 12 and the detection circuit 8-2 that the engine has warmed up.

That is, since the resistance value of the water temperature sensor 12 changes depending on the water temperature and the voltage across the resistor also changes depending on the water temperature, the detection circuit 8-2 compares this voltage with a voltage that is equally constrained to the temperature after completion of warm-up. The result is manually input to the judgment circuit 9.

Similarly, the ignition coil 11 controls the engine rotation, the throttle valve switch 14 controls the throttle valve position, the ignition key 13 controls the ignition key position, and the output of the main circuit 4 controls the injector drive pulse width, which are controlled by the respective detection circuits 8- 1.8-4.
It is input to the judgment circuit 9 through 8-3.8-5.

When determining that the engine has been sufficiently warmed up from this information, the judgment circuit 9 connects the output terminal a, which outputs an output corresponding to the maximum air amount of the intake air amount sensor 15, which may change suddenly during measurement, to the intake air amount sensor 15. The variable fixing circuit 7 connected to the output terminal A which outputs an output corresponding to the amount of intake air is operated to keep the outputs of the output terminals a and b of the intake air amount sensor 15 constant.

That is, this variable fixing circuit 7 has a constant voltage diode Z
D and the transistor Tr 1 are connected in series, and when operated, the voltage between a and b becomes a constant voltage equal to the sum of the Zener voltage of the constant voltage diode ZD and the saturation voltage of the transistor Tr1.

At the same time, the inspector is requested to "accelerate" through the display circuit 10.

When the inspector depresses the accelerator pedal in response to this display and performs an acceleration operation, the throttle valve switch 14 changes from idle to off to full.

During this process, the difference in the injector drive pulse width immediately before and after the throttle valve switch 14 changes from off to full is calculated by the judgment circuit 9 through the detection circuit 8-5, and compared with a pre-stored reference value. be done.

The result as to whether the reference value is satisfied is outputted from the judgment circuit 9 as a result output to a display device such as a printer or a lamp (not shown).

Further, when the throttle valve switch 14 is turned from off to on, the inspection can be performed in the same manner.

FIG. 4 is a block diagram of another embodiment of the present invention, FIG. 5 is a circuit diagram of another embodiment, and FIG. 6 is a flowchart for explaining its operation.

The difference between FIG. 1 and FIG. 4 is that in FIG. 1, a sensor output signal that needs to be constant during inspection, such as an intake air amount sensor output signal, is forced to be constant in advance.
While measurements were taken immediately before and after the injection amount increase, the fourth
In the figure, a circuit for fixing variables is not provided, and measurements and calculations are performed only after the injection amount is increased to determine whether or not the injection quantity is good or bad.

In FIG. 4, reference numeral 2 denotes sensors that input information such as the intake air amount, engine speed, and water temperature to the main body circuit 4, and the main body circuit 4 determines the basic fuel injection amount X from these input information via the connector A.

is calculated and a drive signal with a pulse width is output to the injection valve 5 via the connector B.

Reference numeral 3 denotes sensors that input information on the ignition key, throttle valve switch, etc. to the main body circuit, and the main body circuit 4 calculates the corrected fuel injection amount Y from this input information.

is calculated and an injector drive signal corresponding to the correction amount is output as the same pulse width.

The test circuit 6' is connected to the main circuit 4 through the connector C during the test.
The basic fuel injection amount X is calculated from the output X of the sensors 2 that determine the basic fuel injection amount, and the actual injection valve drive signal X is output from the main body circuit 4.

Also enter these X and X. It is determined which difference is within the specified range or not and output as a result output.

Furthermore, when the inspection circuit C receives a signal y from the sensors 3 that determine the corrected fuel injection amount indicating that the correction has been made, it calculates the corrected fuel injection amount Y, and thereby calculates the actual injection amount output from the main circuit 4. Valve drive signal X.

The value obtained by subtracting the previously calculated basic fuel injection amount Output to display.

FIG. 5 is a circuit diagram of one embodiment, in which the sensors 2 correspond to the intake air amount sensor 21 and the negative terminal of the ignition coil 22, and the trigger input signal from the sensors 3 to the test circuit 6' is sent to the ignition key. , is the throttle valve switch.

When the ignition key is set to 5 TART, the starting amount increases Yl, and when the ignition key is set to ON or IG, the idling amount increases Yl.
2. When the throttle valve switch goes from IDLE to OFF, the start increase Y3 is the same (when the throttle valve switch goes to Full, it increases FULL Y4) When the ignition key is on and the throttle valve switch is OFF.
In the steady state, X, which corresponds to the basic fuel injection amount, is inspected.

The characteristics of the embodiment shown in FIG. 4 are that, compared to the embodiment shown in FIG. The reason is that the measurement operation can be simplified and speeded up since the measurement and calculation are performed later.

To further express this mathematically, the injector drive pulse width tg in the embodiment of FIG. 4 is 1, K2, K3, where the water temperature and intake air temperature signals are t; t); Function of water temperature, f (n); Function of engine speed, f (u): Function of intake air amount, which can be transformed and expressed as.

The left side f (s) of equation (4) corresponds to the increase in the pulse width tg, and the first term on the right side is the output Xo + Y of the main circuit 4.

, and the second term on the right side is Y. The subtracted value corresponds to the basic fuel injection amount X.

K1, K2, and K3 are constants, and t g , f (
n), f(u) should be measured immediately after the increase trigger signal is applied, and f(t) should be stored in the test circuit in advance because it becomes thick in a short time (it will not change). You can stay there.

Therefore, the right side of equation (4) is a value that can be calculated by the test circuit, and the quality of the device is diagnosed based on whether f (s) as a result of this calculation is within a preset reference value.

A specific example will be explained with reference to the circuit of FIG. 5 and the flowchart of FIG. 6.

First, when testing a full increase in the test circuit, for example, 3
If the throttle valve switch 14 turns on at around 1,000 rpm, the inspector should say, ``When you step on the accelerator, the speed is 300 rpm.''
The display device 10 instructs the driver to increase the engine speed to approximately 0 rpm (no load).

Then, the full contact of the throttle valve switch, which is one of the correction sensors, is turned on.

Based on this signal, the main circuit 4 of the electronic fuel injection device generates an amount of increase, and as a result outputs the injector drive pulse width tg.

In the test circuit 6', the throttle valve switch Ful
f(n), f(u) immediately after detecting l contact ON
.

It detects f(t) and also receives the signal tg from the main circuit 4, and calculates f(s) by calculating the right side of equation (4) with the already stored values 1, K2, and K3.

Depending on whether this value is within the reference value or not, the display device 10 displays OK or NG as a result.

As described above, according to the present invention, comprehensive diagnosis is possible without disconnecting the connection wire of the electronic fuel injection device that is mounted.
Tests can be performed in a manner similar to actual usage conditions, making it easy to perform functional diagnosis in a short period of time.

Particularly on the lines of automobile manufacturing plants, each main circuit of the electronic fuel injection system and the connection wires including each sensor are tested before being installed, but even if each unit is in good condition, mistakes may occur during the assembly process. It is necessary to inspect the assembly in the assembled state in consideration of the above, and if the present invention is used to confirm the operation in such a final line, comprehensive inspection can be performed without disconnecting the connecting wires, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a flowchart for explaining its operation, FIG. 3 is a circuit diagram of one embodiment of FIG. 1, and FIG. 4 is a block diagram of another embodiment of the present invention. ,
FIG. 5 is a circuit diagram of one embodiment, and FIG. 6 is a flowchart for explaining its operation. Explanation of symbols, 1...Electronic fuel injection device, 2...
... Status sensors, 3... Operation command sensors, 4... Body circuit, 5... Injection valve,
6... Inspection device, T... Variable fixing circuit, 8... Detection circuit, 9... Judgment circuit,
10...Display circuit, 11...Ignition coil, 12...Water temperature sensor, 13...
...Ignition key, 14...Throttle valve switch, 15...Intake air amount sensor.

Claims (1)

[Claims] 1. In an inspection device that diagnoses the functionality of an electronic fuel injection device that operates a fuel injection valve by calculating a basic fuel injection amount and a corrected fuel injection amount from signals detected by various sensors,
The basic fuel injection amount and the actual fuel output by the electronic fuel injection device are calculated by receiving signals branched from the connection line connecting the sensors that determine the basic fuel injection amount and the electronic fuel injection device. When the fuel injection amount is corrected by a sensor that determines whether the fuel injection amount is equal to the injection valve drive signal and determines the corrected fuel injection amount, the basic fuel injection calculated from the actual fuel injection valve drive signal is 1. A testing device for an electronic fuel injection device, comprising a testing circuit that determines whether or not correction has been performed normally by subtracting a quantity.