JPH0537428A - Multiple transmitter for vehicle - Google Patents

Abstract

PURPOSE:To realize the precise fault diagnosis of a sensor at low cost. CONSTITUTION:A sensor node 10 equipped with a car speed sensor 11, engine node 20 equipped with a tarbin sensor 21 and total managing system (TMS) node 30 to monitor a multiple transmission line 1 and the operating states of all the node are connected to the multiple transmission line 1. The TMS node 30 receives the communication data of the tarbin sensor 21 transmitted from the engine node 20 through the multiple transmission line 1 and calculates the approximate value of the car speed from the received communication data. By comparing the car speed measured value of the car speed sensor 11 similarly received from the sensor node 10 through the multiple transmission line 1 with the approximate value calculated in advance, it is decided whether there is any fault at the car speed sensor 11 or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle multiplex transmission device equipped with a node having a sensor such as a vehicle speed sensor.

[0002]

2. Description of the Related Art Recently, in the field of automobiles, the number of electrical components such as switches, sensors, actuators, etc. has increased with the progress of electronics, and the wire harness connecting the electrical components has become bloated and complicated. Has become a problem. Therefore, a multiplex transmission system in which one transmission line is shared by a large number of electrical components has been receiving attention. In particular,
Nodes for the various electrical components and nodes for antilock brake control (ABS), automatic gear shift control (EAT), four-wheel steering control (4WS), engine control (EGI), etc. are connected to the multiplex transmission line, respectively. A time division multiplex transmission network is constructed. Each node transmits / receives communication data to / from another node through the multiplex transmission path. In particular, a node having a sensor for converting a physical quantity indicating the behavior of a vehicle such as a vehicle speed sensor into a measurement signal, that is, a sensor node is important to transmit the measured value of the physical quantity as communication data to a multiplex transmission line based on the measurement signal. Have a function.

By the way, if a failure such as a disconnection or a short circuit occurs in a multiplex transmission line composed of twisted pair lines, communication between nodes becomes impossible. The failure of the multiplex transmission line itself can be detected by, for example, the circuit disclosed in Japanese Patent Laid-Open No. 61-224596. On the other hand, if an abnormality occurs in the sensor in the sensor node,
Since it hinders the control function of the node that has executed the control based on the communication data transmitted from the sensor node, it is necessary to perform some kind of fail-safe processing.
Therefore, it is not enough to detect the failure of the multiplex transmission line itself as described above, and it is also necessary to constantly diagnose whether or not the sensor has an abnormality. Conventionally, two sensors for measuring the same physical quantity are provided in one sensor node, and the failure of the sensor is diagnosed by comparing the outputs of both sensors in the sensor node.

[0004]

As described above, the conventional vehicle multiplex transmission device has a problem that the cost is high because the sensor is duplicated for the purpose of the failure diagnosis of the sensor.

By the way, a configuration is adopted in which a monitoring node called a total managing system (TMS) (hereinafter referred to as TMS node) is connected to a multiplex transmission line, and the operating states of all other nodes are monitored by the TMS node. There were cases. This TMS node has a failure diagnostic function for diagnosing failures of multiple transmission lines, communication chips of each node, sensors, actuators, etc., a failsafe shutoff command to the failed node, and a warning lamp for failure notification. With a processing function when a failure is found, such as turning on,
It had an alternative function to substitute the function of the failed node. However, since the conventional TMS node determines whether or not there is a failure in the sensor based on only the communication data received from the sensor node having the sensor to be diagnosed, the physical quantity to be measured is correctly converted by the sensor. It was not possible to make a detailed diagnosis of whether or not

An object of the present invention is to realize detailed failure diagnosis of a sensor at low cost.

[0007]

In order to achieve the above object, the solution means of the present invention uses an output of a second sensor for measuring a physical quantity different from that of a first sensor which is a target of failure diagnosis. Based on this, failure diagnosis of the first sensor is performed. Specifically, the present invention relates to a first aspect of vehicle behavior.
And a sensor node for transmitting the measured value of the first physical quantity as communication data to the multiplex transmission line based on the first measurement signal. The second sensor for converting a second physical quantity indicating a vehicle behavior different from the first physical quantity into a second measurement signal, and the second measurement signal based on the second measurement signal. The presence or absence of the failure of the first sensor is determined by comparing the calculation value for calculating the approximate value corresponding to the physical quantity of 1 with the measurement value obtained by the sensor node and the approximate value calculated by the calculation means. Therefore, a configuration including a failure determination means for the purpose is adopted.

[0008]

According to the present invention, the first sensor, which is the object of failure diagnosis, converts the first physical quantity into the first measurement signal. The sensor node having the first sensor transmits the measurement value of the first physical quantity as communication data to the multiplex transmission line based on the first measurement signal. On the other hand, the second sensor converts a second physical quantity which is a physical quantity in the same vehicle but different from the first physical quantity into a second measurement signal. An approximate value corresponding to the first physical quantity is calculated from the second measurement signal by the calculating means, and the first sensor malfunctions by comparing the measured value obtained by the sensor node with the approximate value calculated by the calculating means. The presence or absence of is determined.

[0009]

1 is a block diagram showing an embodiment of a vehicle multiplex transmission apparatus of the present invention. As shown in the figure, a number of nodes are connected to the multiplex transmission line 1 formed of, for example, a twisted pair line to form a time division multiplex transmission network. Sensor node 10, engine node 20
And three nodes, TMS node 30, are shown. In addition to this, the automatic transmission control (EA
Although an EAT node that controls T), a node that has a switch, a node that has an actuator, etc. are connected, they are not shown. Communication between nodes via the multiplex transmission line 1 proceeds in units of signals called frames. One frame is, for example, SD (StartDelimiter
) Code, priority code, frame ID code, data length, data 1 to data N, and check code fields. The node that intends to perform transmission transmits a frame to which a frame ID code indicating that it is the transmission source is attached. At this time, the fields of data 1 to data N whose length is displayed in the data length field include data related to a plurality of nodes. Each of the other nodes recognizes the start of the frame by receiving the SD code, knows whether or not the frame is addressed to itself based on the frame ID code, and starts reception if the frame is addressed to itself. Further, the end of the frame is recognized by receiving the check code.
As described above, the communication between the nodes is advanced.

The sensor node 10 has one vehicle speed sensor 11. This vehicle speed sensor 11 is attached to, for example, a transmission unit and operates a sensor element such as a built-in reed switch, Hall IC or magnetoresistive element by a rotating magnetic field to output a pulse signal of a number proportional to the vehicle speed as a measurement signal. It is a thing. That is, if the vehicle speed is V and the number of pulses of the output of the vehicle speed sensor 11 per unit time is P1, then V = K1 × P1 (K1 is a proportional constant). The sensor node 10 is a vehicle speed sensor 11
It has a function of transmitting to the multiplex transmission line 1 a frame including, as data, the measured value V of the vehicle speed obtained from the output of 1.

The engine node 20 includes a turbine sensor 2
Has 1. The turbine sensor 21 outputs a number of pulse signals proportional to the turbine rotation speed as a measurement signal. That is, the turbine rotation speed is A, and the number of pulses per unit time of the output of the turbine sensor 21 is P2.
Then, A = K2 × P2 (K2 is a proportional constant) holds. In addition to the function of controlling the engine (EGI), the engine node 20 also has a function of transmitting to the multiplex transmission line 1 a frame including, as data, the measured value A of the turbine rotation speed obtained from the output of the turbine sensor 21.

In addition to the conventional functions, the TMS node 30 has a vehicle speed measurement value V transmitted from the sensor node 10.
Is received as a data, and a frame containing the measured value A of the turbine speed transmitted from the engine node 20 as data is received, and the approximate value of the vehicle speed is obtained from the data of the measured value A of the turbine speed in the latter frame. The vehicle speed sensor 1 is calculated by calculating V ′ and comparing the measured value V of the vehicle speed in the former frame with the calculated approximate value V ′ of the vehicle speed.
It also has a function of determining the presence / absence of the failure of 1. That is, the TMS node 30 of the present embodiment has the functions of the calculation means and the failure determination means.

Next, the operation of the above vehicle multiplex transmission device will be described. The EAT node (not shown) receives an input of a frame including data of the vehicle speed sensor 11 and a frame including data of the throttle position switch from the sensor node 10 through the multiplex transmission line 1, executes an operation based on the input, and then performs the operation. The frame including the resultant data is transmitted to the multiplex transmission line 1 as an actuator drive signal. This actuator drive signal drives the solenoid of the shift valve, which is the target actuator. However, if an abnormality occurs in the vehicle speed sensor 11,
Since the control function of the EAT node that has executed the control based on the communication data transmitted from the sensor node 10 is hindered, it is necessary to perform some kind of fail-safe processing. Therefore, the TMS node 30 constantly diagnoses whether or not the vehicle speed sensor 11 is normal.

FIG. 2 is a flow chart showing the procedure for executing the failure diagnosis of the vehicle speed sensor 11 in the TMS node 30. As shown in the figure, the TMS node 30 first inputs the measured value A of the turbine speed by the turbine sensor 21 transmitted from the engine node 20 in step S1. In step S2, an approximate value V'of the vehicle speed is calculated from the measured value A based on the formula V '= kxnxA. Here, n is a gear ratio obtained from the range position (P, R, N, D, S, L), and k is a proportional constant determined by the tire radius and the like. Then, in step S3, the sensor node 1
It waits for the input of the vehicle speed measurement value V by the vehicle speed sensor 11 transmitted from 0. While the vehicle speed measurement value V is not input, the process returns to step S1 and step S2 to update the vehicle speed approximate value V '. When the sensor node 10 transmits a frame including the vehicle speed measurement value V as data, the vehicle speed measurement value V is input and the process proceeds to step S4. In step S4, the vehicle speed measurement value V is compared with the vehicle speed approximate value V'calculated in step S2. At this time, if the deviation between the measured vehicle speed V and the approximate vehicle speed V'is within a predetermined threshold value, the vehicle speed sensor 1
1 is determined to be sound, and the process returns to step S1. on the other hand,
If the deviation exceeds the threshold value, it is determined in step S5 that a failure has occurred in the vehicle speed sensor 11, and fail-safe processing such as system down of the sensor node 10 is executed.

As described above, according to the present embodiment, the turbine sensor 21 of the conventional engine node 20 is used even if two vehicle speed sensors are not provided in the sensor node 10 for failure diagnosis unlike the conventional case. Therefore, the failure diagnosis of the vehicle speed sensor 11 of the sensor node 10 can be realized at low cost. Further, since the vehicle speed measurement value V obtained by the vehicle speed sensor 11 and the vehicle speed approximate value V ′ based on the turbine sensor 21 are compared, whether the vehicle speed sensor 11 has converted the vehicle speed into an output pulse almost accurately. Can be diagnosed.

Although the turbine sensor 21 is used for the failure diagnosis of the vehicle speed sensor 11 in the above description, a wheel speed sensor may be used instead of the turbine sensor 21. However, the present invention is applicable not only to the vehicle speed sensor 11 but also to failure diagnosis of other sensors. A plurality of other sensors may be used for failure diagnosis of one sensor. It is also possible to adopt a configuration in which the TMS node 30 is provided with a verification sensor that can be used for failure diagnosis of a plurality of sensors. Also, T
The calculation function for calculating the approximate value and the function for determining the failure, which the MS node 30 has, may be provided in the sensor node itself having the sensor that is the target of the failure diagnosis.

[0017]

As described above, according to the present invention, the same vehicle behavior is exhibited in order to realize the failure diagnosis of the first sensor for measuring the first physical quantity indicating the vehicle behavior. A second physical quantity that is different from the first physical quantity
A second sensor for measuring the physical quantity of the first sensor is used, an approximate value corresponding to the first physical quantity is calculated based on the output of the second sensor, and the measured value obtained by the first sensor is calculated. Since the configuration for determining the presence / absence of the failure of the first sensor is adopted by comparing with the calculated approximate value, unlike the conventional method, two sensors for measuring the same physical quantity are not provided in one sensor node. The failure diagnosis of can be realized. Moreover, since a conventional sensor can be used as the second sensor that serves as a verification reference for the first sensor, failure diagnosis of the sensor can be realized at low cost. Further, since the measured value obtained by the first sensor is compared with the approximate value obtained by the second sensor, it is necessary to make a detailed diagnosis as to whether or not the correct measured value is obtained by the first sensor. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle multiplex transmission device of the present invention.

FIG. 2 is a flowchart showing an execution procedure of a vehicle speed sensor failure diagnosis in the TMS node in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Multiplex transmission line 10 ... Sensor node 11 ... Vehicle speed sensor (1st sensor) 20 ... Engine node 21 ... Turbine sensor (2nd sensor) 30 ... TMS node (arithmetic means, failure determination means)

Claims (1)

Claim: What is claimed is: 1. A first sensor for converting a first physical quantity indicating a behavior of a vehicle into a first measurement signal, wherein the first sensor is provided based on the first measurement signal. A multiplex device for a vehicle, comprising a sensor node for transmitting a measured value of one physical quantity as communication data to a multiplex transmission path, wherein a second physical quantity showing a behavior of a vehicle different from the first physical quantity is a second physical quantity. Second sensor for converting into the measurement signal, calculation means for calculating an approximate value corresponding to the first physical quantity based on the second measurement signal, the measured value and the approximate value And a failure determination means for determining whether or not there is a failure in the first sensor by comparing the above.