JPH076876B2 - Vehicle diagnostic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle diagnostic device that measures a signal output from a control device to measure the state of sensors, actuators, or the like.

[Problems to be Solved by Conventional Techniques and Inventions] In recent years, an engine mounted on a vehicle electronically controls an air-fuel ratio and the like to exhibit comfortable drivability, purify exhaust gas, and save energy. The fuel economy and engine output are being improved.

Output signals from various sensors that detect the engine state,
Alternatively, if the output signals to various actuators such as injectors are not accurate, it becomes difficult to control the engine accurately, which leads to a decrease in drivability, deterioration of exhaust mission or fuel consumption, and a decrease in output of the engine.

In recent complicated electronic control systems, it is difficult to immediately understand the cause of failure even if a failure occurs in control equipment, sensors, actuators, etc. A vehicle diagnostic device capable of easily checking output signals from sensors or signals output from the electronic control device to various actuators is indispensable.

For example, in the vehicle diagnostic device disclosed in Japanese Patent Laid-Open No. 58-12848, a case of checking idle instability will be described as an example. The fuel injection amount is calculated from the fuel injection pulse width for the injector, and compared with each of these predetermined reference values to determine whether the idle speed is normal.

However, in the vehicle diagnostic device disclosed in this prior art, the fuel injection time of the actuator is measured,
It is not possible to calculate the duty ratio from the duty signal for operating the duty solenoid of this actuator to diagnose the operating state of the actuator and the like, and it is not possible to obtain high measurement accuracy.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides a vehicle diagnostic device capable of accurately measuring a pulse width, a duty ratio, and the like, and significantly improving the measurement accuracy. It is intended to be provided.

[Means and Actions for Solving the Problem] According to the present invention, a timer for measuring a pulse width output from the control device is built in a control unit of a vehicle diagnostic device that reads an output signal of a control device mounted on a vehicle. The pulse width is measured according to this timer, and the fuel injection time from the injection or the duty ratio is measured from the duty signal to the actuator.

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

1 shows an embodiment of the present invention, FIG. 1 is an external view of a vehicle diagnostic device connected to a vehicle control device, FIG. 2 is a block diagram of a vehicle control device and a vehicle diagnostic device, FIG. Is a waveform diagram of a duty pulse, and FIG. 4 is a flowchart showing a vehicle diagnosis procedure.

In the figure, reference numeral 1 is a vehicle such as an automobile, and 2 is a control device mounted on the vehicle 1 for performing air-fuel ratio control and the like. ) 4, a read only memory (ROM) 5, an input interface 6 and an output interface 7
Connected through.

In addition, a cooling water temperature sensor 9 is connected to the input interface 6.
Water temperature signal Tw, the air-fuel ratio feedback signal λ of the O ₂ sensor 10, the intake air amount signal Q of the intake pipe negative pressure sensor 11, the air conditioner operation signal SWa of the air conditioner switch 12, the vehicle speed signal S of the vehicle speed sensor 13, and the idle switch 14 Idle operation signal SW
i, throttle opening signal Tr of throttle opening sensor 15
θ, Neutral switch 16 neutral operation signal SW
n, the rotation speed signal N of the engine rotation speed sensor 17, etc. are input.

In the control device 2, the various signals are processed according to the program stored in the ROM 5 and once stored in the RAM 4, and then the CPU 3 performs various arithmetic processing based on the stored data. A control signal based on the arithmetically processed data is sent to the output interface 7,
A control signal is output to the canister control device 19, the EGR actuator 20, the idle control actuator 21, the ignition coil 22, and the injector 23 via the drive circuit 18.

Further, the control device 2 is provided with an external connection connector 24, and the external connection connector 24 is provided with a connector 26 provided on the vehicle diagnostic device main body 25.
Connected via 27.

This vehicle diagnostic device main body 25 is provided in a dealer service station, etc., and is provided with a control unit 28, a power supply circuit 29, etc. inside, and an indicator unit outside.
30, a display 31, a keyboard 32, etc. are provided. Further, a detachable memory cartridge 34 is connected to the control unit 28 via a connector 33.

The control unit 28 includes a central processing unit (CPU) 36 connected to each other via a bus 35, a read / write memory (RAM) 37, a timer 38 including a frequency counter, and an input / output (I / I).
O) port 39 and other I / O port 40 connected to the CPU 36 above
Is provided.

Output signals of the various sensors and various switches from the output interface 7 of the control device 2 are input to the input side of the I / O port 40. The indicator unit 30 is connected to the output side of the I / O port 40.

A mode selection signal of the keyboard 32 and various control signals output from the output interface 7 of the control device 2 to the drive circuit 18 are input to the input side of the other I / O port 39. Further, the output side of the I / O port 39 is connected to the input interface 6 of the control device 2 and the display 31.

Further, the memory cartridge 34 is adapted to be selectively connectable so as to have compatibility with the programs of the control device 2 which are different for each vehicle type. A read-only memory (ROM) 41 having a program is provided.

Further, the timer 38 is provided with a clock pulse transmitting element 42 which outputs a synchronizing signal.

Further, the power supply circuit 29 connected to the control unit 28 is connected to the power supply Vcc of the vehicle 1 via the ON / OFF operation switch 43.

Next, the operation of the embodiment having the above configuration will be described.
It should be noted that this vehicle diagnosis is performed in an actual vehicle state.

First, the connector 26 of the vehicle diagnostic device body 25 is connected to the external connection connector 24 provided in the control device 2 of the vehicle 1 directly or via the adapter harness 27.

For example, when measuring the fuel injection pulse width (time) T1 output from the output interface 7 of the control device 2,
After turning on the operation switch 43 of the vehicle diagnostic device body 25 and confirming the initialization, the corresponding mode (for example, F → 1 → 2 → ENT) is input by the key of the keyboard 32.

Then, this mode is read by the control unit 28 of the vehicle diagnostic device body 25, the timer mode of the timer 38 is selected, and then the timer 38 sets the fuel injection pulse width (time).
T1 is counted, and this is temporarily stored in RAM37. Then, the CPU 36 converts the fuel injection data stored in the RAM 37 into a physical quantity (converts the count number into time) and displays, for example, 1, 3 on the display 31. To turn on the fuel injection pulse width (time) T1
Notify that it is 1,3 (msec).

Then, the operator determines whether the fuel injection pulse width (time) T1 displayed on the display 31 is within the set value range, and whether there is an abnormality in the fuel injection system or a deviation from the reference value. Diagnose width.

Further, when diagnosing the operating state of the switches, for example, the idle switch 14, after initializing the control unit 28, the corresponding mode is input by the keyboard 32.

Then, release the foot from the accelerator lever or step on it, The blinking state of is diagnosed, and whether the operation of the idle switch 14 is normal is diagnosed.

When measuring the output signal from the control device 2 to the duty solenoid (not shown) provided in the EGR actuator 20, the idle control actuator 21, etc., that is, the duty ratio D accompanying the operation of each duty solenoid, First, after initialization, the corresponding mode is entered using the keyboard 32.

As a result, the timer mode is selected, and in the control unit 28, the timer 38 counts the pulse width T1 and the pulse period T2 (see FIG. 3) and temporarily stores them in the RAM 37.
Then, the CPU 36 reads the pulse width data T1 and the pulse period data T2 stored in the RAM 37, and the duty ratio D
Is calculated (D = T1 / T2).

Then, the duty ratio D is converted into a physical quantity and displayed on the display 31. This display 31
Check whether the value displayed in
It is diagnosed whether or not the signal is normally output to the duty solenoid of each actuator such as the actuator 20 and the idle control actuator 21.

The above-mentioned diagnosis procedure will be described with reference to the flowchart of FIG.

First, in step 101, the operation switch 43 of the vehicle diagnostic device body 25 is turned on, and in step 102, the control unit 28 is initialized.

Then, in step 103, the mode input to the keyboard 32 is read, and in step 104, the control device 2 of the vehicle 1 is requested to transmit data corresponding to the mode. And
In step 105, the corresponding data is received.

Next, in step 106, it is determined whether or not the timer mode is selected. If not selected, the process proceeds to step 107. If the timer mode is selected, the step 10 is selected.
Go to 8 to read the timer and count the above data.

Then, in step 107, the data is calculated and converted into a physical quantity, the numerical value is displayed on the display 31 in step 109, and the process returns to step 103.

The present invention is not limited to the above embodiment, and for example, the vehicle diagnostic device main body 25 may have a built-in battery so that only the data signal is input from the control device 2 of the vehicle 1.

As described above, according to the present invention, the control unit for reading the output signal of the control device mounted on the vehicle has the built-in timer for measuring the pulse width output from the control device. Therefore, the pulse width, the duty ratio, and the like can be accurately measured, and the measurement accuracy can be significantly improved, which is an excellent effect.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is an external view of a vehicle diagnostic device connected to a vehicle control device, FIG. 2 is a block diagram of a vehicle control device and a vehicle diagnostic device, FIG. Is a waveform diagram of a duty pulse, and FIG. 4 is a flowchart showing a vehicle diagnosis procedure. 1 ... vehicle, 2 ... control device, 25 ... vehicle diagnostic device main body, 28 ... control unit, 38 ... timer, T1 ... pulse width, T2
…… Pulse cycle, D …… Duty ratio.

Claims (1)

[Claims] 1. A vehicle diagnostic device, wherein a control unit of a vehicle diagnostic device for reading an output signal of a control device mounted on a vehicle includes a timer for measuring a pulse width output from the control device. apparatus.