JP2634598B2 - Electronic control unit for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a failure diagnosis system used by connecting data stored in a memory in an electronic control unit of an internal combustion engine to the electronic control unit. The present invention relates to an electronic control unit for an internal combustion engine that can be initialized or erased by using a tester.

[Conventional technology]

FIG. 1 is a diagram showing a configuration of an electronic control unit of the present invention and a conventional internal combustion engine, which will be described later. In FIG. 1, 1 is an engine, 2 is a piston, 3 is a cylinder, 4 is a cylinder head, An exhaust manifold 6 is provided at an exhaust port 5 of each cylinder of the cylinder head 4, and an intake manifold 8 is provided at an intake port 7 of each cylinder of the cylinder head 4.
Are connected to each other.

The intake manifold 8 is provided with a surge tank 9 for preventing pulsation of intake air.
Is provided with an intake pressure sensor 10 for detecting the pressure in the intake manifold 8, that is, the intake pipe pressure Pm.

Next, 11 is a throttle valve for controlling the amount of intake air sent to each cylinder via the surge tank 9, and 12 is an idle speed control valve (IS) for controlling the amount of intake air flowing through a bypass passage 12A bypassing the throttle valve 11.
CV) and 13 are intake air temperature sensors that detect the intake air temperature. The throttle valve 11 has a throttle valve opening sensor that outputs a signal corresponding to the opening of the throttle valve 11 and an ON state when the engine 1 is idling. A throttle position sensor 14 having an idle switch to be operated is directly connected.

An oxygen concentration sensor 15 is attached to the exhaust manifold 6 and detects the oxygen concentration in the exhaust gas. A water temperature sensor 16 detects the cooling water temperature of the engine 1. A igniter 19 is connected to a spark plug 18 of the engine 1 at a predetermined timing. The distributor 20 for applying the high voltage output from the engine 1 is attached to the distributor 17, and the rotation speed of the engine 1
A rotation speed sensor that generates a pulse signal corresponding to Ne, 21 is a starter sensor that detects the operation state of a starter motor (not shown) that starts the engine, and 22 is an air conditioner switch (hereinafter, referred to as Reference numeral 23 denotes a vehicle speed sensor provided on driven wheels for detecting the running state of the vehicle, and detecting the number of revolutions of the driven wheels.

Various detection signals of the intake pressure sensor 10, the intake temperature sensor 13, the throttle position sensor 14, the oxygen concentration sensor 15, the water temperature sensor 16 and the rotation speed sensor 20 are output to a control circuit 25. Various control processes such as fuel injection amount control of the fuel injection valve 26 and ignition timing control of the spark plug 18 are executed based on

27 receives power from a battery 28 shown in FIG.
The control circuit 25 is connected by input / output signal lines and has communication means capable of transmitting and receiving signals, and is mainly used for reading data generated by a self-diagnosis function built in the control circuit 25, such as a car data reader. And a self-diagnosis result display device (hereinafter referred to as a tester) used for services.

Next, the control circuit 25 will be described in detail with reference to FIG. Reference numeral 50 denotes a central processing unit (hereinafter referred to as CPU) for performing arithmetic processing and logical processing of fuel injection amount control, idle speed control or ignition timing control, 51 denotes an address data bus from the CPU 50, and 52 stores a control program and control constants. A read-only memory (hereinafter referred to as ROM), 53 is a random access memory (hereinafter referred to as RAM) for temporarily storing control calculation data and input / output data, and 54 is a digital device which responds to a switching signal from the engine speed sensor 20 or the vehicle speed sensor 23. Input port, 55 is throttle position sensor 1
4.Analog input port that responds to analog signals from oxygen concentration sensor 15, etc., 56 to fuel injector 26 and igniter 19
This is an output port for outputting the calculation processing result of the CPU 50.

The CPU 50 and the ROM 52, the RAM 53, the digital input port 54, the analog input port 55, and the output port 56 are connected by an address data bus 51, respectively.

28 is an on-board battery, 29 is an ignition switch, 57 is a battery backup power supply that is directly connected to the battery 28 and supplies power to the RAM 53 even when the ignition switch 29 is opened, and 58 is a control circuit 25 when the ignition switch 29 is closed. 1 shows a circuit constant-voltage power supply that supplies power to the whole.

Note that, in the figure, indicates that each other is connected.

Next, the operation of the conventional electronic control unit for an internal combustion engine will be described. The control circuit 25 in FIG. 1 performs fuel injection control, idle speed control, ignition timing control, and the like.

The fuel injection control calculates a basic injection fuel amount from input signals of the intake pressure sensor 10 and the engine speed sensor 20, performs a predetermined correction according to an engine cooling water temperature, and then performs a final injection fuel amount. Is calculated and converted to the valve opening time of the fuel injection valve 26, and then the fuel injection valve 26 is driven.

These calculations are executed by a program stored in the ROM 52 of FIG. 2, and the calculation data is temporarily stored in the RAM 53. Input signal required for calculation is digital input port
Read from 54 or analog input port 55.

On the other hand, the calculation result is output from the output port 56, and the fuel injection valve 26 is driven. In addition, as an exhaust gas purification measure, the amount of injected fuel is controlled in response to an input signal of the oxygen concentration sensor 15 shown in FIG. 1 to achieve a target air-fuel ratio.

The idle speed control stabilizes the engine speed during idling, and the engine load increases when the air conditioner switch 22 is turned on or when the power steering, electric load (not shown) is turned on, or the like. In order to prevent the rotation speed from decreasing, the intake air amount is controlled by driving the idle speed control valve 12.

The ignition timing control is determined by the engine speed and the intake pressure in the manifold, and determines the final ignition timing by correcting the ignition timing map stored in the ROM 52 as a basic ignition timing by the cooling water temperature or the like. An output signal is sent to the igniter 19 through the output port 56 shown.

In the above control, the RAM 53 of FIG. 2 stores not only the operation data of the CPU 50, but also the ignition switch 29 including learning values for absorbing aging and variations of each system component, or failure diagnosis history of sensors and actuators.
Is stored and held by the backup of the battery.

The tester 27 is for detecting a defective portion with a dera in case of a malfunction of the internal combustion engine of the automobile, etc., and can read out the failure diagnosis history of the above-mentioned sensors and actuators. It is an effective device in that it can be repaired and the defect can be found quickly and accurately.

The tester 27 sends transmission data to the digital input port 54 in the control circuit 25 and receives data from the output port 56.

In this case, the transmission data is command data indicating which data in the RAM 53 of the control circuit 25, while the reception data is
The data itself in the RAM 53.

For example, when checking whether the oxygen concentration sensor 15 is normal or abnormal, a command “1” is transmitted from the tester 27 to the control circuit 25. The control circuit 25 receives the command “1”, extracts the data of the RAM 53 storing whether the oxygen concentration sensor 15 is normal or abnormal, and transmits the data to the tester 27.

The tester 27 has a display unit, and displays whether the oxygen concentration sensor 15 is normal or abnormal. The tester 27 has a keyboard switch. The above-described command is generated by operating the keyboard switch, and transmitted from the tester 27. With the above procedure, the failure diagnosis is also performed on other sensors and actuators.

[Problems to be solved by the invention]

Since the conventional electronic control unit for an internal combustion engine is configured as described above, the learning value or the failure diagnosis history stored in the RAM 53 is returned to the initial value when parts are replaced or erased using a dealer or the like. When necessary, the connection is opened by opening the connection terminal of the battery 28 and shutting off the power supply to the RAM 53.

However, when the connection terminal of the battery 28 is opened, the power supply of other electronic devices such as a clock and a radio is also cut off, so that there is a problem that all the stored data of these electronic devices are erased.

The present invention has been made in order to solve such a problem, and it is possible to return the storage data of only the electronic control unit of the internal combustion engine to the initial value or delete the storage data without deleting the storage data of other electronic devices. It is another object of the present invention to provide an electronic control unit for an internal combustion engine which has a simple structure and is inexpensive.

[Means for Solving the Problems] An electronic control unit for an internal combustion engine according to the present invention is a storage unit for storing a diagnosis result obtained by diagnosing a state of each internal combustion engine operating state detection unit (various sensors, etc.) as a diagnosis target. (RA
M53) and codes (codes 1 to 30) are assigned correspondingly so that identification of various diagnosis targets and requests for initialization of the storage means can be distinguished from each other, and request signals of the codes corresponding to the requests are assigned. A request is received from a separate diagnosis result display device (tester 27) connected to the electronic control unit via the same transmission path (27d), and a request is determined based on the code of the request signal. Means for outputting the diagnosis result of the object to the diagnosis result display device, and for initializing or erasing the data stored in the storage means when the request signal includes a code corresponding to the initialization request (steps 100 to 107) ).

[Operation] In the electronic control device of the present invention, when a request signal transmitted from the diagnosis result display device via the same transmission path is received, the code assigned to the request signal is determined, and the request is detected. Thereby, the diagnosis result of the requested diagnosis target is output to the diagnosis result display device, and the data stored in the storage means is initialized or erased.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. The overall configuration of the present invention is as shown in FIG. 1, and the internal configuration of the control circuit 25 is as shown in FIG. FIG. 3 is a flowchart illustrating an embodiment of the present invention. The flowchart of FIG. 3 relates to transmission and reception of signals with the tester 27 by a control program stored in the ROM 52 of the control circuit 25.

First, the code of the requested device to be diagnosed is transmitted from the tester 27. In step 100 of FIG. 3, the control circuit 25 receives the code from the tester 27. Therefore, it is determined which code has been received according to the target table of the codes and the devices to be diagnosed shown in FIG.

In step 101, it is determined whether or not the code is 1, and "YES"
If so, in step 101A, the oxygen concentration sensor 15 outputs the diagnosis result to the tester 27 with the device to be diagnosed.

Similarly, in step 102, it is determined whether or not the throttle position sensor 14 is a device to be diagnosed in step 104, and if the codes match, the diagnostic results of the device in steps 103 and 105 are sent to the tester 27, respectively. Is output.

In addition to the original functions of the tester 27, functions according to the present invention are executed in step.

That is, in FIG. 4, the code 30 is a function for executing the initialization of the RAM 53. It is determined in step 106 whether or not the code is 30, and if "YES", the RAM 53 is initialized in step 107. The contents of this initialization are executed by the CPU 50 in accordance with the control program in the ROM 52, and for example, learning values of control parameters for absorbing aging and variations of each system component, and failure diagnosis histories of sensors and actuators are initialized. Or erase it. That is, in the present invention, a code for specifying a target and requesting a diagnosis result of the target or a code for instructing initialization or erasure of the RAM 53 is transmitted from the tester 27 to the control circuit 25 via the same transmission line 27d.
And the control circuit 25 performs processing according to the code.

In the above embodiment, the tester 27 has a code and a device to be diagnosed as shown in FIG. 4, but has a failure diagnosis function of this kind together with the control circuit 25, and has a function like the code 30 in FIG. If it has, the same effect as the above embodiment can be obtained.

[Effects of the Invention] An electronic control unit for an internal combustion engine according to the present invention includes a storage unit that stores a diagnosis result obtained by diagnosing the state of each internal combustion engine operating state detection unit as a diagnosis target, and specifies the various diagnosis targets and the storage unit. Codes are assigned correspondingly so that the initialization requests can be distinguished from each other, and a request signal of the code corresponding to the request is transmitted from the separate diagnostic result display device connected to the electronic control unit in the same manner. Received through the path, determines the request based on the code of the request signal, outputs a diagnosis result of the requested diagnosis target to the diagnostic result display device, and outputs a code corresponding to the initialization signal to the request signal. Is included, means for initializing or erasing the storage data in the storage means is provided, so that a request for a diagnosis result of each diagnosis target and an instruction to initialize or delete the storage data are provided. In this case, it is only necessary to transmit the same type of code signal from the diagnosis result display device to the control means via the same transmission path, and further, a dedicated transmission path is provided for an initialization request signal, or a dedicated control circuit is provided. Since there is no need to provide an input terminal, an inexpensive device having a simple configuration can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electronic control unit for an internal combustion engine of the present invention, FIG. 2 is a block diagram showing a detailed configuration of a control circuit in the electronic control unit of the internal combustion engine of FIG. 1, and FIG. FIG. 4 is a flow chart for explaining the operation of the electronic control unit for an internal combustion engine according to the present invention. FIG. 4 is a diagram showing the relationship between the code of a tester and the device to be diagnosed in the electronic control unit for an internal combustion engine according to the present invention. 1 ... engine, 10 ... intake pressure sensor, 13 ... intake temperature sensor, 14 ... throttle position sensor, 20 ... rotation speed sensor, 21 ... starter sensor, 22 ... air conditioner switch, 23 ... vehicle speed sensor , 25 ... control circuit, 27 ... tester. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] An electronic control unit for an internal combustion engine that determines at least a fuel amount and controls an output of the internal combustion engine according to detection results of a plurality of internal combustion engine operation state detection means for detecting an operation state of the internal combustion engine of the vehicle. Storage means for storing a diagnosis result obtained by diagnosing the state of each of the internal combustion engine operating state detection means as a diagnosis object, and a request for identification of various diagnosis objects and a request for initialization of the storage means. A code is assigned to each of them, and a request signal of the code corresponding to the request is received from a separate diagnosis result display device connected to the electronic control unit via the same transmission path, and the code of the request signal is received. The request is discriminated based on the request, and the diagnosis result of the requested diagnosis target is output to the diagnosis result display device, and the request signal includes a code corresponding to the initialization request. Electronic control device for an internal combustion engine, characterized in that it comprises means for initializing or erase data stored in said storage means to.