JP3255957B2 - Automotive electronic control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control unit for a vehicle which controls output devices such as an internal combustion engine for a vehicle and other vehicle equipment by using three or more central processing units (hereinafter referred to as CPU).

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No. 61-212,651 has a CPU for controlling an injection valve and a CPU for controlling an ignition circuit in order to accurately control an internal combustion engine at high speed in an automobile with much noise. There is disclosed an electronic control unit for an internal combustion engine in which two CPUs are mutually connected by communication means to transfer data mutually. However, according to the prior art, when the number of CPUs becomes three, these three CPUs are connected in a ring shape,
Since all CPUs are interconnected, in this case, six sets of communication means are required, and the amount of hardware required for communication increases. In particular, if the number of CPUs increases, the effect is great.
If four are used, twelve sets of communication means for interconnecting all CPUs are required.

[0003] Japanese Patent Application Laid-Open No. 2-62601 discloses that
The two CPUs are mutually connected by two sets of communication means to transmit and receive frame-structured data, and when a frame error of the received data is detected, transmission of the next data is prohibited for more than one frame time. Although an electronic control unit for an internal combustion engine for a vehicle having means for performing the above-described operation is disclosed, the prior art also requires a large number of communication means and interrupts the transmission of data in a running vehicle in a fail-safe manner. It is not preferable because it cannot be achieved.

[0004]

The problems to be solved are:
Even when data communication is performed over more than one CPU, the third CPU inputs data to the second CPU via the first communication means for performing communication from the first CPU to the second CPU.
The detected data can be detected as abnormal, and the 3C
Fail-safe processing can be performed in PU, and C
It is an object of the present invention to provide an electronic control unit for a vehicle which requires a small increase in hardware for communication even when the number of PUs increases to three or more.

[0005]

SUMMARY OF THE INVENTION Accordingly, in order to solve the above-mentioned problems, the present invention provides an automotive vehicle including at least three central processing means for controlling output devices such as an automotive internal combustion engine and other automotive devices. an electronic control unit, first, second and third central processing means Ri Contact <br/> given to the output device the control output is introduced to the sensor input required, and the first central processing unit A first communication unit for transferring data from the second central processing unit to the second central processing unit; and a second communication unit for transferring data from the second central processing unit to the third central processing unit. Is before
The first and second communication means from the first central processing means
To the output device based on the data input through
Performing an operation for a given control output,
Processing means for transmitting the first communication data from the first central processing means;
Communication with the second central processing means via the communication means.
When the normal state is detected, the abnormal data indicating this abnormality is stored in the second
Transferring to the third central processing means via communication means;
The third central processing means receives the input of the abnormal data.
Control, the control of the output device
And an electronic control unit for a vehicle, characterized in that the electronic control unit is switched to the electronic control unit. Further, according to the present invention, the third central processing unit can fail-safe the data from the first central processing unit. That is, the first
A second central processing unit from the central processing unit via the first communication unit;
If the data input to the arithmetic processing means is abnormal, the second
The central processing means sends the abnormal data to the second communication means.
The third central processing means transfers the data to the third central processing means.
Switches to fail-safe control based on this abnormal data.
Can be replaced. In addition, since at least the first and second communication means perform communication only in one direction between the three central processing means, the communication means and the amount of hardware for communication are relatively small, and the central processing means ( Even if the number of CPUs increases to three or more, the increase in the amount of hardware related to communication may be small.

[0006]

FIG. 1 is a block diagram showing an embodiment of the present invention. The electronic control unit for a vehicle according to the present embodiment includes a CPU 1 that mainly controls the fuel injection valve 28, a CPU 2 that mainly controls the automatic transmission 32, and a CPU 3 that mainly controls the ignition timing of the ignition plug 30. Te Each of the CPUs 1 to 3 is connected by the following communication means. CPU1 and CPU
2, the data line 4 for transferring the data obtained by the CPU 1 and the fact that the CPU 2 can receive
They are connected by a transmission permission signal line 7 for transmitting to PU1. Similarly, the CPU 2 and the CPU 3 are connected by the data line 5 and the transmission permission signal line 8. Similarly, the CPU 3 and the CPU 1 are connected by the data line 6 and the transmission permission signal line 9. Further, reference numeral 10 denotes a synchronization signal line for synchronizing communication, which is output from the CPU 1 and input to the CPU 2 and the CPU 3.

The CPU 1 stores various arithmetic programs executed by the CPU 1 and the fuel injection amount (fuel injection valve 28).
A read-only memory (hereinafter, referred to as ROM) 33 for storing various tables used for calculating the valve opening time of the engine, and a random access memory (hereinafter, referred to as RAM) 34 for temporarily storing the operation result. ing. The fuel injection valve 28 may be provided for each cylinder.

The CPU 2 also has a ROM 37 for storing various calculation programs executed by the CPU 2 and shift patterns (various tables used for calculating the energization timing of various shift solenoids of the automatic transmission 32) and the like. A RAM 38 for temporarily storing results is provided. The automatic transmission 32 includes a plurality of transmission solenoids, but is illustrated as one for simplicity.

The CPU 3 similarly stores various arithmetic programs executed by the CPU 3 and ignition timing patterns (various tables used for calculating the ignition timing of an ignition circuit for applying a high voltage to the ignition plug 30). RO
An M35 and a RAM 36 for temporarily storing the operation result are provided. The number of spark plugs 30 is, for example, 4 in accordance with the number of cylinders.
Four simple internal combustion engines are required.

The input side of the CPU 1 has a waveform shaping circuit 1
1. Input circuit 12 and analog-to-digital converter (A /
D converter) 13 is connected. The waveform shaping circuit 11 includes cylinder discrimination signals G1 and G2 from the cylinder discrimination sensors 16 and 17.
The rotation signal NE of the rotation sensor 18 is input. The input circuit 12 includes an idle signal IDL of an idle switch 19, a neutral signal NSW of a neutral switch, and a starter signal S of a starter switch 21.
TA is input. On the input side of the A / D converter 13, the air flow signal AFM of the air flow meter 22, the cooling water temperature signal THW of the water temperature sensor 23, the intake temperature signal THA of the intake temperature sensor 24, the throttle opening signal TA of the throttle sensor 25, and the battery voltage are provided on the input side. A battery voltage signal BAT for the sensor 26 has been introduced.

A waveform shaping circuit 15 is connected to an input side of the CPU 2, and a vehicle speed sensor 27 is connected to an input side of the waveform shaping circuit 15 to receive a vehicle speed signal SPD. On the input side of the CPU, a waveform shaping circuit 11
It is connected in the same way as U1.

An example of data transferred by communication between the CPUs 1, 2, and 3 is shown below.

The CPU 1 and the CPU 2 determine the shift timing and the ignition timing of the load amount data QN indicating the amount of load, the cooling water temperature data THW, the intake air temperature data THA, the throttle opening data TA, the battery voltage data BAT, and the like. And data indicating whether the communication from the CPU 3 to the CPU 1 is abnormal.

The vehicle speed data SP is transmitted from the CPU 2 to the CPU 3.
D, among the data received from the CPU 1, the load amount data QN, the cooling water temperature data THW, and the intake air temperature data TH.
A and data necessary for determining the ignition timing, such as battery voltage data BAT, and data indicating whether communication from the CPU 1 to the CPU 2 is abnormal are transferred.

From CPU3 to CPU1, ignition timing data AOP indicating the ignition timing, data required to determine the fuel injection amount and injection timing such as vehicle speed data SPD among the data received from CPU2, and CPU2 from CPU2 to CPU3. The data indicating whether the communication is abnormal is transferred.

FIG. 2 is an explanatory diagram showing a method for detecting a communication abnormality. The communication data has a start bit 39, a data bit 40, a parity bit 41, and a stop bit 42. A parity bit 41 is added after the data bit 40, and a parity bit is set on the transmission side so that the data bit 40 and a bit indicating the parity bit “1” are odd. When the bit is an even number, a communication error can be detected as a parity error. When the receiving side knows the data bit length in advance, the receiving side detects the stop bit before the reception of the data bit length is completed, or when the stop bit cannot be detected despite the completion of the reception. And detects a communication error as a synchronization error.

A communication abnormality is detected when the abnormality is detected by the abnormality detecting means or when data is to be received (4 m
s) for which data cannot be received. A specific cause may be a ground short of the data line and / or the synchronization signal line.

Next, a fail-safe method in the event of a communication error in the CPU 3 will be described. FIG. 3 shows a flowchart of the fail-safe processing in the CPU 3. CPU
1 and the CPU 2 perform the same processing. CPU
2 to the interrupt routine generated at the end of communication (S43)
When a communication error from the CPU 2 to the CPU 3 is detected due to the parity error or the synchronization error described above (S
In 44), since all the received data are considered abnormal, the fail-safe value is stored in the vehicle speed data SPD (S45), information for communicating the communication abnormality to the CPU 1 is stored (S46), and the load amount data is stored. The fail safe value is stored in QN, cooling water temperature data THW, intake air temperature data THA, throttle opening degree data TA, battery voltage data BAT, and the like (S47). Further, the ignition timing is fixed (S49). If the communication is normal in step S44, when the CPU 2 controlling the automatic transmission 32 detects an abnormality in communication from the CPU 1 to the CPU 2 based on the received data (S48), the CPU among the received data
1 is considered to be abnormal, the load amount data QN, the cooling water temperature data THW, and the intake air temperature data TH
A, throttle opening degree data TA, battery voltage data B
The fail safe value is stored in the AT or the like (S47), and the ignition timing is further fixed (S49).

In the case of a communication error, there is a case where no reception interrupt occurs. Therefore, as shown in FIG. 4, in the timer interrupt (S50) every 4 ms, there is no reception interrupt for 16 ms continuously. In the case (S51), the fail safe value is stored in the vehicle speed data SPD or the like (S52), and the load amount data Q is stored.
N, cooling water temperature data THW, intake air temperature data THA, throttle opening degree data TA, and battery voltage data BA
The fail safe values such as T are stored (S53), and the ignition timing is fixed (S54). After the above processing is performed, the transmission processing to the CPU 1 is performed (S55), whereby the CP
Even if the communication from U2 to CPU3 is abnormal, the failsafe value is transmitted to CPU1.

[0020]

[Other Embodiments] The communication abnormality information need not be transferred by the same means as other communication data, but may be transmitted by another means (for example, by using another port). The number of CPUs is not limited to three, and may be four or more.

As described above, the electronic control unit for a vehicle according to the present invention comprises an electronic control unit for a vehicle including at least three central processing means for controlling output devices such as an internal combustion engine for a vehicle and other automotive devices. A first central processing unit, a first central processing unit, a second central processing unit, and a second central processing unit. And a second communication unit for transferring data from the second central processing unit to the third central processing unit, wherein the second communication unit has an abnormality in the first central processing unit. Is provided, the third central processing means can fail-safe the data from the first central processing means, Amount of hardware of the communication from communicating only there are excellent effects such as extremely small.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electronic control unit for a vehicle according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a communication abnormality detection method.

FIG. 3 is a flowchart showing a fail-safe process in a central processing unit (CPU 3).

FIG. 4 is a flowchart showing a fail-safe process in the central processing unit (CPU 3) in the case of a communication error that does not generate a reception interrupt.

[Explanation of symbols]

1, 2, 3, ... central processing unit (CPU), 4,
5, 6 ... data line, 7, 8, 9 ... transmission permission signal line, 10 ... synchronization signal line, 11 ... waveform shaping circuit,
12 ... Input circuit, 13 ... Analog digital (A /
D) Converter, 15 ... waveform shaping circuit, 16,17 ...
Cylinder discrimination sensor, 18 ... rotation sensor, 19 ... idle switch, 20 ... neutral switch, 2
1. Starter switch 22. Air flow meter
23 ... water temperature sensor, 24 ... intake air temperature sensor, 2
5 ... Throttle sensor, 26 ... Battery sensor,
27 ... vehicle speed sensor, 28 ... fuel injection valve, 30 ...
Spark plug, 32 ... automatic transmission, 39 ... start bit, 40 ... data bit, 41 ... parity bit, 42 ... stop bit, S43-S55 ... step.

Claims (2)

(57) [Claims] 1. An electronic control unit for a vehicle including at least three central processing means for controlling output devices such as an internal combustion engine for a vehicle and other automotive devices, comprising: a first, a second and a third electronic control unit; the central processing means is applied to the output device the control output is introduced to the sensor input needed,
A first communication unit for transferring data from the first central processing unit to the second central processing unit; and a second communication unit for transferring data from the second central processing unit to the third central processing unit.
Communication means, wherein the third central processing means comprises a first central processing means.
The data input from the stage via the first and second communication means.
Control output to the output device based on the data
And the second central processing means performs the first central processing.
The second central processing from a stage via the first communication means
If an error in communication with the means is detected, an error indicating this error is detected.
The data is transferred to the third central processing unit via the second communication means.
Transfer sense means, said third central processing means, said abnormal data is input
Control, the control of the output device
An electronic control unit for a vehicle, characterized in that the electronic control unit is switched to a control. 2. Internal combustion engines for automobiles and other automobiles
At least three central controls for controlling output devices such as devices
An electronic control unit for a vehicle including arithmetic processing means, The first, second and third central processing means are provided with necessary sensor inputs.
Power and control output to the output device.
And from the first central processing means to the second central processing means
First communication means for transferring data, and second central processing
Means for transferring data from the means to the third central processing means.
Communication means, The third central processing means is a first central processing means.
The data input from the stage via the first and second communication means.
Control output to the output device based on the data
And calculate The second central processing means is a first central processing means.
From the first communication hand The second central processing through a stage
When an abnormality in the data input to the means is detected, the abnormality is detected.
The abnormal data indicating the normal state is transmitted to the second
3 Transfer to central processing means, The third central processing means receives the input of the abnormal data.
Control, the control of the output device
Electronic control equipment for vehicles characterized by switching to control
Place.