JPH0577874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an automotive multiplex signal transmission system having a function of multiplexing signal outputs from each sensor group and transmitting the signal output to the computer when controlling the running of the vehicle using an on-vehicle computer. Regarding equipment.

Specifically, in a computer control system that comprehensively performs engine control such as fuel injection control, ignition control, and idle speed control, and transmission control, etc., using an on-vehicle microcomputer, each The present invention relates to a transmission device that transmits signals detected from a group of sensors to a computer using a time division multiplexing method.

Conventionally, engine control systems rely on various sensors in the engine room, such as the amount of air flowing into the engine, the temperature of the air flowing in, the temperature of the cooling water, the throttle opening, the engine cylinder discrimination signal, the top dead center position signal, and the rotation speed. , crank angle, oxygen sensor, battery voltage sensor, etc., signals are obtained by connecting multiple individual conductors, each identified by each sensor, to an electronic control unit (ECU) installed in the passenger compartment. , is transmitted and processed to the ECU. This method of connecting multiple long-distance wires from the engine room to the ECU in the passenger compartment has the following drawbacks. Firstly, multiple wiring lines require a large space for wiring; secondly, the weight of the wirings and therefore manufacturing costs increase; and thirdly, the output impedance of the sensor is high, which reduces the output signal level. However, there are drawbacks such as being susceptible to noise, which can cause malfunctions, and fourth, requiring a multi-pole connector for wiring between the engine room and the passenger compartment, which poses a problem with the reliability of the connector. did. In computer-based control systems, the number of sensors tends to increase, and the number of multiple signal lines increases, making the above drawbacks an increasingly serious problem.

The present invention has been made to improve the above-mentioned drawbacks, and when transmitting multiple signals detected by multiple sensor groups from the engine room to the ECU in the passenger compartment, the signal groups are time-division multiplexed. At the same time, one data frame of the above-mentioned time division multiplexed signal is transmitted in synchronization with the timing signal representing the rotation angle of the rotating mechanism, which is one output of the sensor group. ECU
One object of the present invention is to provide a multiplex signal transmission device for an automobile that can be connected with a single signal line.

However, since the generation timing of the timing signal fluctuates as the engine speed changes, it is not easy to time-division multiplex and transmit this timing signal and the other signals.

In other words, when time-division multiplexing both a timing signal whose generation timing fluctuates synchronously with changes in engine speed and other signals, each frame of the time-division multiplexed signal is When transmitting at regular intervals (when transmitting the timing signal and other signals periodically), the generation time value of the timing signal must be serially encoded.

In this way, serially encoding a timing signal (a time value that corresponds to a predetermined engine rotation angle) and incorporating it into a time division multiplexed signal causes a delay in processing time, making it impossible to transmit the timing signal in real time. Can not.

On the other hand, the timing signal whose generation time is undefined is transmitted at the same time as the timing signal is generated (or after a certain time delay from the generation time), and each frame of a time division multiplexed signal consisting of other engine status signals is transmitted at fixed time intervals. (when the timing signal is sent irregularly and the sensor output is sent regularly), of course,
There is a possibility that the two overlap in time, and further signal processing is required to avoid this.

Another object of the present invention is to solve the above-mentioned problems, and it is desirable to avoid transmission delays as much as possible by transmitting a timing signal (a signal representing the time at which a predetermined engine rotation angle value is reached). An object of the present invention is to provide a multiplex signal transmission device for an automobile that is capable of time-division multiplex transmission of many types of signals while suppressing delays.

In order to achieve such an object, in the present invention, a plurality of outputs from a rotation angle sensor for detecting the engine rotation angle in the engine room and other various sensors are collected from each sensor excluding the rotation angle sensor among the sensor outputs. a data converter that periodically receives the output and converts it into serial encoded data, and a transmission controller provided in the engine room that converts the serial encoded data into a time division multiplexed signal and sends it to the transmission path. A multiplex signal transmitting device for an automobile, comprising: a transmitting section comprising: a receiving section provided in a vehicle interior to receive and decode the time division multiplexed signal via the transmission path, the transmitting control section The present invention is characterized in that the output from the rotation angle sensor is used as a timing signal, and in synchronization with the timing signal, frame unit data in which the time division multiplexed signal is added to the start bit is sent to the transmission path.

Next, one embodiment of the present invention will be described.

FIG. 1 is a block diagram showing the inventive concept of the present invention.

The rotation mechanism 20 and the rotation angle sensor 12 are electromechanically coupled, and the rotation angle sensor 12 sends a rotation angle electrical signal proportional to the mechanical rotation position to the data input unit 1.
Output to 4. A group of multiple sensors 2 installed in the engine system for the vehicle's driving control system.
2 outputs an electrical signal proportional to each detected physical quantity to the data input section 14. Data input section 1
4 inputs these electrical signals and encodes the analog signals into digital signals. The output signal of the data input section 14 is arranged into a predetermined format by a data conversion section 16 and converted into encoded serial data. A plurality of serial data output from the data converter 16 are input to the transmission controller 18 . The transmission control unit 18 transmits each plurality of serial data to the buffer register 24 in a time division multiplexing manner in synchronization with a timing signal representing the rotation angle of the rotation mechanism output from the rotation angle sensor 12.
The encoded data set in the buffer register 24 is transmitted through a single signal line 25 to a receiving buffer register 26 provided on the receiving side.
The data received by buffer register 26 on the receiving side is decoded and processed by receiving device 28.
The receiving device 28 sends a signal to the CPU 30,
The CPU 30 processes the received signal and outputs a predetermined control signal, and each actuator group 32 operates based on the control signal.

In summary, the feature of the present invention is that each plurality of data is encoded and time-division multiplexed, and this multiplexed signal is sent out in synchronization with a timing signal proportional to the rotation angle of the rotating mechanism. Therefore, data detected from various sensor groups can be transmitted to the receiving device side together with a timing signal requesting real-time response information. Since the time division multiplexing method is used, a single transmission line can be used as the transmission line.

Hereinafter, the present invention will be explained in detail based on more specific examples.

FIG. 2 is a block diagram showing the structure of an embodiment of the automobile multiplex signal transmission apparatus of the present invention realized by a software-controlled microcomputer system. An electronic control unit (hereinafter referred to as "ECU") 40 is provided in the engine compartment along with a group of various sensors.
ECU1 (40) functions as a transmitter in the present invention,
The signal is transmitted via the transmission line 25a to the ECU 2 (70) provided in the vehicle interior, which corresponds to the receiving section in the present invention. ECU1 (40) includes a microcomputer system 41 having a CPU, memory, etc.
Convert various analog signals to digital signals
It consists of an AD converter 42, an input interface 44 for inputting and connecting various digital signals to a microcomputer system, and an electro-optical conversion circuit 46 for converting output signals from electrical to optical signals. The various sensor groups 22 specifically include an air flow meter 51 that measures the amount of intake air, a water temperature sensor 52 that measures the radiator water temperature, a battery voltage sensor 53 that measures the battery voltage, and a throttle position that measures the throttle opening. The rotation angle sensor 12a outputs a synchronization signal synchronized with the rotation angle from the distributor, and the oxygen sensor 55 measures the oxygen gas concentration. Among these, sensors 51 to 53 that output analog signals
is connected to the AD converter 42, and its output signal is
It is input into the microcomputer system 41. On the other hand, a sensor 54 that outputs a digital signal,
12a, 55 are connected to the input/output interface 44, and their signals are input to the microcomputer system. Further, the distributor outputs a top dead center position signal G1 and a cylinder discrimination signal G2 as shown in FIG. A rotation angle signal N corresponding to the rotation angle of the crankshaft synchronized with the rotation of the engine is outputted from the rotation angle sensor 12a in a waveform as shown in FIG. 3c.

The present invention transmits time division multiplexed data in synchronization with this rotation angle signal N. The rotation angle sensor 12a consists of a signal rotor and a pickup coil installed in the distributor. The signal rotor is a rotor with 24 gear-like peaks, and the pickup coil electromagnetically coupled to the signal rotor outputs a signal as shown in Figure 3c. On the other hand, the receiving side provided inside the vehicle has an ECU 2. The ECU 2 (70) includes a photoelectric conversion circuit 74 that photoelectrically converts serial data received from the transmission line 25a, and a microcomputer system 71 that inputs the signal. The microcomputer system 71 performs numerical calculations for engine control according to a predetermined program based on predetermined received data, and then outputs the output interface 7.
A signal is outputted to an injector 61 and an igniter 62, which are the actuator group 32, through the actuator 8 to control the ignition timing or idling.

Next, the data transmission method of the device of the present invention will be explained.

FIG. 4 shows a timing signal output from the rotation angle sensor and a multiplexed signal transmitted in synchronization with this timing signal. FIG. 5 is a block diagram showing the structure of a data frame of a multiplexed signal. FIG. 6 similarly shows an example of the structure of a data frame. As shown in FIG. 5, the data frame of the multiplexed signal is composed of 16 bits from start bit b0 to parity bit b15, the last bit. The b0 bit is a start bit representing a low level, and is a falling pulse that comes after the data of the stop bit group B0 that maintains a constant high level. This start bit is used to obtain a synchronization signal when receiving data, and detects the falling time of the start bit.
Each bit of the following data is sampled. Each data frame is transmitted in synchronization with the point in time when the rotation angle signal N output from the rotation angle sensor shown in FIG. 4 passes through a constant voltage level V from a high level to a low level. As a result, as shown in FIG. 4d, data such as D1 to D6 are synchronized with the timing signals, and time division multiplexing is performed within data such as D1 to D6.

The structure of each data frame is specifically explained as follows. Data block B2 is a block containing information for transmitting in synchronization with rotation angle signal N that the crank position is at top dead center (G1 signal). For example, if the timing signal of the rotation angle signal also represents the top dead center signal (G1), set it to "10".
data is transmitted. Also, if the timing signal N is synchronized with the cylinder discrimination signal G2, it will send data of "01", and if it is not synchronized, it will send data of "11".
shall be. That is, the above data takes the formats shown in FIGS. 6a, b, and c, respectively. Therefore, in FIG. 4, the start bit of data frame D1 is also synchronized with the top dead center signal, and has the data structure shown in FIG. 6a.

The start bit of data frame D5 is also synchronized with the cylinder discrimination signal, and has the data structure shown in FIG. 6b. The start bits of data frames D2, D3, D4, and D6 are synchronized only with the rotation angle signal N, and have the data structure shown in FIG. 6c.

Data block B3 is a data block containing information indicating the type of numerical content of data block B4. For example, the amount of incoming air is coded as "1000," the incoming air temperature as "0100," and the oxygen sensor data as "0010." Data block B4
is encoded numerical data consisting of 8 bits. In the case of an analog signal, it is digitized and represented as numerical data divided into 8 bits, that is, 256 classes. Further, in cases such as on/off signals, any one bit is used. For example, the oxygen sensor output is set to b7, and the throttle position sensor output is set to "1" when b8 is set to "1". data block B5,
That is, bit b15 is a parity bit that adjusts the parity of the data frame. The next block B0 is a stop bit. Such data frames are sent out in synchronization with the timing signal N, as shown in FIG. Upon reception, the start bit of this data frame is detected to detect the real time of the timing signal, and a synchronization signal for bit sampling of the data included thereafter is obtained. Here, it is desirable that the bit rate of this multiplexed signal satisfies the following equation.

Tr＞(2×Ne×Np×Bf/60)...(1sce) Here, Tr is the bit rate, Ne is the maximum number of rotations per minute, and Np is the output of the rotation sensor per rotation of the rotating mechanism. The number of pulses, Bf is −
This is the number of bits in the data frame.

As an example, the maximum rotation speed Ne of a rotating machine is
9000rpm, rotation angle sensor output pulse number Np is 12,
If the number of bits of a data frame is 16 bits, the bit rate will be 57.6 Kbit/sec or more.

Here, when the above equation is expanded, the number of bits Bf in one data frame becomes Bf<Tr×60/Ne×Np×1/2. In other words, the number of bits in one data frame
Bf can only be used up to half or less of the maximum number of bits defined by the bit rate Tr of the multiplexed signal, the maximum rotation speed Ne of the rotating machine, and the number of output pulses Np of the rotation angle sensor. This is to prevent synchronization errors when receiving multiplexed signals.

In other words, in order to prevent synchronization errors when receiving multiplexed signals, it is necessary to accurately detect stop bits, but if the bit length of the stop bits is shortened, the receiving side cannot determine whether it is data or stop bits. may be unclear.

Therefore, the bit length that does not exist as data,
In other words, stop bits can be detected accurately by making the length longer than one data frame. Therefore, the number of bits that can be used as data is less than half the maximum number of bits defined by the formula shown above.

Next, the software for controlling the microcomputer will be explained with reference to FIGS. 7 and 8.
FIG. 7 is a flowchart of the processing software of ECU1. The microcomputer 41 is activated by the application of the stabilizing voltage and executes the arithmetic processing of the control program. step
Execution starts from step 100, and the initial state is set in the next step 101. Next, the process moves to step 102, where it is determined whether the timing signal of the rotation angle sensor has been detected. If the rotation angle signal is not detected, the loop will stop until it is detected. When the timing signal is detected, the process moves to the next step 103 and outputs one data frame of serial data prepared in advance. do. As a result, one data frame synchronized with the timing signal is transmitted to the electro-optical conversion circuit 46 and the transmission line 2.
5a on the receiving side. In the next step 104, the analog signals output from the various sensor groups are converted into digital signals and stored. In the next step 105, digital signals from various sensor groups are input and stored in a predetermined area. In the next step 106, the various data described above are converted into the predetermined data structure described above. In this way, the output of the serial data is prepared, and the process returns to step 102 to output the data when detected by the timing signal.

By repeating the above routine, various data can be time-division multiplexed in synchronization with the timing signal.

Figure 8 shows the receiving side, that is, the one installed inside the vehicle.
This is a flowchart of a method controlled by the microcomputer 71 of the ECU 2. The microcomputer 71 is also applied with a stabilized power supply, and becomes operational, and proceeds to step 200.
Start execution from. In step 201, the initial state is set in the same manner as described above. Step 202
receives the serial signal. Analyze the data according to the predetermined format described above. That is,
It detects one bit from the start bit, analyzes the data, and stores it in a predetermined memory. Also, in the next step 203, the analog signal inside the vehicle,
For example, the air temperature of an air conditioner is input into the computer via an AD converter. Further, in step 204, a digital signal inside the vehicle, such as a signal from a vehicle speed sensor, is input and stored in the data area. Step 205 when all kinds of data are collected
Step 206 determines the fuel injection amount, or step 206 calculates the ignition advance angle and outputs a signal for starting a predetermined injector and igniter. The computer repeats such a routine.

The sensors described in the above embodiments are merely examples, and any sensor for signals other than the synchronization signal may be used. or,
Although a signal proportional to the rotation angle of the engine is used as the synchronization signal, for example, in a transmission control system, the synchronization signal may be transmitted in synchronization with a timing signal that is a vehicle speed signal. Further, the transmission line may be an electric wire or an optical fiber. Further, in this embodiment, a system using a computer in which the present invention can be implemented most easily has been described, but it is also possible to assemble individual digital circuits having the functions shown in FIG. This allows synchronization and multiplexing. Furthermore, the type of actuator that processes and activates the received signal is arbitrary.

In summary, the present invention encodes signals detected from various sensors and transmits them as serial data by time division multiplexing and at the same time transmitting them in synchronization with a timing signal proportional to the rotation angle of a rotating mechanism. This is what I did. Therefore, it is possible to simultaneously transmit various signals and timing signals that require real-time information over a single transmission line. Therefore, the disadvantages of individually transmitting data using multiple wires are improved. Specifically, there is no need to take up a large wiring space. No weight increase. Therefore, cost reduction can be achieved. Furthermore, the use of optical fibers can prevent the influence of noise.

Furthermore, according to the present invention, the following effects can be achieved.

(a) Even though the timing signal and other sensor outputs are time-division multiplexed, there is no delay in transmission of the timing signal. Furthermore, the configuration of a circuit or program related to processing of timing signals in time division multiplexed signals is simplified.

(b) Since the transmission timing (transmission time) of the time division multiplexed signal itself is the timing at which the predetermined engine rotation angle value represented by the timing signal is reached, there is no need to transmit the timing signal itself. For example, the edge of the start pulse of the time division multiplexed signal of the sensor output can be directly used as the timing signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the inventive concept of a multiple signal transmission device for an automobile according to the present invention. FIG. 2 is a configuration diagram showing a specific configuration of an automobile multiplex signal transmission device according to an embodiment of the present invention. FIG. 3 shows the distributor signal and the timing signal output from the rotation angle sensor of the same embodiment. FIG. 4 shows how the signals of the same embodiment are time-division multiplexed,
FIG. 2 is an explanatory diagram illustrating a method of synchronizing with a timing signal. FIG. 5 is a data configuration diagram showing the configuration of one data frame of the same embodiment. FIG. 6 is also a data configuration diagram. FIGS. 7 and 8 are flowcharts showing the processing method of the microcomputer used in the same embodiment. 10...Multiple signal transmission device, 12... Rotation angle sensor, 14... Data input section, 16... Data conversion section, 18... Transmission control section.

Claims (1)

[Scope of Claims] 1. Periodically receiving sensor outputs other than the rotation angle sensor among a plurality of sensor outputs output from a rotation angle sensor for detecting engine rotation angle and other various sensors in the engine room; a data conversion unit that converts each into serial encoded data;
a transmitting unit including a transmission control unit provided in an engine room that converts the serial encoded data into a time division multiplexed signal and sends it to a transmission path; and a transmission unit that receives the time division multiplexed signal via the transmission path. An automotive multiplex signal device comprising: a receiving section installed in a vehicle interior for decoding; the transmission control section uses an output from the rotation angle sensor as a timing signal; A multiplexed signal transmission device for an automobile, characterized in that frame-by-frame data with the time division multiplexed signal added to a start bit is sent to the transmission path.