JP2005257304A - Diagnostic method for acceleration detection unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnostic method for acceleration detection units, capable of accurately performing even failure decision of an acceleration detection unit which is not equipped with an external input terminal for diagnostic signals, by performing its diagnosis a plurality number of times. <P>SOLUTION: When power supply is started, the diagnostic portion 12 of the acceleration detecting unit 10 makes an acceleration sensor 11 perform misoperations for diagnosing, and transmits a malfunction code via a communication portion 13 if its operation is not normal. When the failure diagnostic portion 27 of a center unit 20 receives the malfunction code via a communication portion 22, it counts the number of times of the reception of the malfunction code by a malfunction counter 25, and resumes power supply to the detection unit 10, after making a power supply switch portion 21, in a nonconducting state for a predetermined period of time via a power supply control portion 24. A failure discriminating portion 26 discriminates that the detection unit 10 has failure, if the number of times of the reception of the malfunction code reaches three, makes a warning light blink, and makes the control operation for expansion of an air bag corresponding to the detection unit 10 discriminated as in failure stop. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an acceleration detection unit diagnosis method for detecting a collision with an occupant protection device such as an airbag system.

  In the airbag system, it is diagnosed whether the acceleration detection unit that detects an impact at the time of a collision is operating normally. For this reason, the conventional acceleration detection unit is provided with an external terminal for inputting a diagnosis request signal. By supplying a diagnosis request signal to this external terminal, the acceleration sensor in the acceleration detection unit is operated in a pseudo manner, and an acceleration is detected. And whether it is outputting normally. In addition, in order to prevent erroneous diagnosis in the vehicle environment, it is determined that the acceleration detection unit is out of order when an output abnormality due to a pseudo operation is detected, for example, three times.

In addition, an airbag device (airbag system) that detects a vehicle collision and deploys an airbag for protecting an occupant includes a center unit and a plurality of satellite units (acceleration detection units). This airbag device connects a center unit and a satellite unit with two signal lines, supplies power from the center unit to the satellite unit, and also transmits acceleration signals and failure diagnosis result signals from the satellite unit to the center unit. To supply. The satellite unit performs failure diagnosis of the acceleration sensor at the timing when the power supply is started, and outputs a failure diagnosis result signal when an abnormality of the acceleration sensor is detected.
Japanese Patent Laid-Open No. 2001-4653

  Since the conventional acceleration detection unit can perform pseudo operation control by external terminal input, it is possible to make a diagnosis multiple times when the output is abnormal. On the other hand, in the case of an acceleration detection unit configured not to have an external input terminal for a diagnostic signal and to perform a self-diagnosis when power supply is started, a diagnosis cannot be performed a plurality of times.

  The present invention has been made to solve such a problem, and is an acceleration that can be diagnosed multiple times for an acceleration detection unit that does not have an external input terminal for a diagnostic signal so that a failure can be accurately determined. An object of the present invention is to provide a detection unit diagnostic method.

In order to solve the above problems, the acceleration detection unit diagnosis method according to the present invention comprises an acceleration sensor, its diagnosis circuit, and output means, and performs self-diagnosis of the acceleration sensor by the diagnosis circuit at the start of power supply. A method for diagnosing an acceleration detection unit that outputs the diagnosis result information via the output means,
When abnormality information is output from the acceleration detection unit, the power supply to the acceleration detection unit is temporarily stopped and then repeated to start power supply, and the number of times abnormality information is output is counted. When the predetermined number of times is reached, it is determined that the acceleration detection unit is out of order.

  According to the acceleration detection unit diagnosis method of the present invention, abnormality information is output as a diagnosis result to an acceleration detection unit that does not have an external input terminal for a diagnosis signal but is configured to perform self-diagnosis at the start of power supply. In doing so, it is possible to execute a plurality of self-diagnosis, and determine a failure of the acceleration detection unit based on the results of the plurality of diagnosis.

  Hereinafter, the best mode for carrying out the invention will be described based on examples.

  FIG. 1 is a block diagram of a main part relating to diagnosis of an airbag system to which the diagnostic method for an acceleration detection unit according to the present invention is applied, FIG. 2 is a diagram showing the arrangement of the acceleration detection unit in the airbag system, and FIG. It is a flowchart which shows the diagnostic method of the acceleration detection unit in a system.

  As shown in FIG. 2, the airbag system includes a first acceleration detection unit (front satellite unit) 10F arranged in front of the vehicle and a second acceleration detection unit (left satellite unit) arranged on the left side of the vehicle. ) 10L, a third acceleration detection unit (right satellite unit) 10R disposed on the right side of the vehicle, and a center unit 20.

  As shown in FIG. 1, each acceleration detection unit (each satellite unit) 10F, 10L, 10R and the center unit 20 are connected by two signal lines 51, 52, respectively. One of the two signal lines is a power supply and signal line 51, and the other is a ground line 52. In FIG. 1, only the connection between one satellite unit and the center unit 20 is shown.

  Each satellite unit 10 </ b> F, 10 </ b> L, 10 </ b> R includes an acceleration detection unit 10. The acceleration detection unit 10 includes an acceleration sensor 11 for detecting acceleration, a diagnosis unit 12 for diagnosing the operation of the acceleration sensor 11 when power is supplied to the acceleration detection unit 10, and a preset collision determination acceleration. A communication unit 13 is provided as output means for outputting collision detection information when an acceleration exceeding it is detected and outputting diagnosis result information of the acceleration sensor. The communication unit 13 transmits the collision detection information and the diagnosis result information superimposed on the power source and the power source supplied via the signal line 51. Reference sign Vdd is a positive-side power supply terminal of the acceleration detection unit 10.

  The center unit 20 is composed of, for example, a PNP transistor or the like, and is transmitted from the power supply switch unit 21 for supplying the ignition power source Vign to the acceleration detection unit 10 in each of the satellite units 10F, 10L, 10R, and the acceleration detection unit 10 side. The communication unit 22 that receives the collision detection information and the diagnosis result information, the control of power supply to the acceleration detection unit 10 and the failure diagnosis of the acceleration detection unit 10, the airbag deployment control (not shown) and the warning light (not shown) CPU 23 for controlling lighting of the warning lamp W / L). Reference numeral Vcc is a stabilized power source and a power source terminal of the CPU 23.

  The CPU 23 is controlled by a control program stored in a ROM (not shown), a power supply control unit 24, a failure diagnosis unit 27 including an abnormality counter 25 and a failure determination unit 26, a W / L control unit 28, and a deployment determination unit 29. And make up.

  In FIG. 1, the center unit 20 shows only the configuration for one satellite unit. Actually, the power supply switch unit 21, the communication unit 22, the power supply control unit 24, the failure, and the like corresponding to each satellite unit. A diagnosis unit 27, a W / L control unit 28, and a deployment determination unit 29 are provided.

  Next, the diagnostic operation of the acceleration detection unit (satellite unit) will be described with reference to FIGS. When the stabilized power supply Vcc is supplied to the center unit 20 (step S1), the power supply control unit 24 drives the power supply switch unit 21 to a conductive state. Thereby, the ignition power source Vign is supplied to the acceleration detection unit (satellite unit) 10 (step S2). When the power is supplied, the acceleration detection unit 10 diagnoses the acceleration sensor 11 by the diagnosis unit 12 (step S3). This diagnosis is made by simulating the acceleration sensor 11 and monitoring its output. The diagnosis unit 12 determines whether the acceleration sensor 11 is operating normally (OK) or not (NG) based on the pseudo-motion output (step S4).

  The diagnosis unit 12 transmits a normal code via the communication unit 13 when the acceleration sensor 11 is operating normally. When the CPU 23 in the center unit 20 receives the normal code via the communication unit 22, the CPU 23 shifts to a normal process assuming that the diagnosis result of the acceleration detection unit 10 is normal (step S6). Here, the normal process is a process of deploying an airbag (not shown) when an impact due to a collision is detected.

  If the diagnosis unit 12 of the acceleration detection unit (satellite unit) 10 determines in step S4 that the acceleration sensor 11 is not operating normally (NG), an error code (abnormal information) is transmitted via the communication unit 13. ) Is transmitted (step S7). When the center unit 20 receives the abnormal code via the communication unit 22, the center unit 20 counts the number of times the abnormal code is received by the abnormal counter 25 in the failure diagnosis unit 27, and the power supply switch unit 21 is connected via the power control unit 24. After controlling to a non-conduction state for a preset time, the power supply switch unit 21 is controlled to a conduction state (step S8).

  Thereby, for example, when an abnormal code is received for the first time, the value of the abnormal counter becomes 1. In addition, after the power supply to the acceleration detection unit (satellite unit) 10 is stopped for a predetermined time, the power supply is started again. Therefore, the diagnosis of the acceleration sensor 11 is performed by the diagnosis unit 12 in the acceleration detection unit (satellite unit) 10, and the diagnosis result is output. Thereby, when an abnormal code is output from the acceleration detection unit (satellite unit) 10, the diagnosis of the acceleration sensor 11 can be repeatedly performed. Further, when the diagnosis result of the acceleration sensor 11 is abnormal, the value of the abnormality counter 25 in the failure diagnosis unit 27 is incremented (+1).

  The failure determination unit 26 determines that the acceleration detection unit (satellite unit) 10 has failed when the value of the abnormality counter 25 is 3 (that is, the number of times of reception of the abnormality code is 3) (step S1). S9). If it is determined that there is a failure, an abnormality of the acceleration detection unit (satellite unit) 10 is displayed visually by flashing a warning lamp (warning lamp) (not shown) via the W / L control unit 28. Information of the acceleration detection unit (satellite unit) 10 determined to be faulty is supplied to the determination unit 29, and the deployment control operation of an airbag (not shown) corresponding to the acceleration detection unit (satellite unit) 10 is stopped. (Step S10). This notifies the occupant of the failure of the acceleration detection unit (satellite unit) 10 and prohibits the airbag deployment operation based on the acceleration detection unit (satellite unit) 10 determined to be a failure.

  If it is determined in step S9 that the acceleration detection unit (satellite unit) 10 is out of order, the failure diagnosis unit 27 controls the power supply switch unit 21 to be in a non-conduction state via the power control unit 24, and the acceleration detection unit ( The power supply to the satellite unit 10 may be stopped.

  In addition, although this Embodiment demonstrated the airbag system, this invention is applicable also to passenger | crew protection apparatuses, such as an automatic seatbelt system.

It is a principal part block diagram regarding the diagnosis of the airbag system to which the diagnostic method of the acceleration detection unit which concerns on this invention is applied. It is a figure which shows arrangement | positioning of the acceleration detection unit in the airbag system. It is a flowchart which shows the diagnostic method of the acceleration detection unit in the airbag system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Acceleration detection unit 10F, 10L, 10R Satellite unit 11 Acceleration sensor 12 Diagnosis part 13 Communication part 20 Center unit 21 Power supply switch part 22 Communication part 23 CPU
24 Power Control Unit 25 Abnormal Counter 26 Failure Determination Unit 27 Failure Diagnosis Unit 28 W / L (Warning Lamp) Control Unit 29 Deployment Determination Unit

Claims (1)

Acceleration sensor, diagnosis circuit thereof, and output means, and diagnosis of an acceleration detection unit that performs self-diagnosis of the acceleration sensor by the diagnosis circuit at the start of power supply and outputs the diagnosis result information through the output means A method,
When abnormality information is output from the acceleration detection unit, the power supply to the acceleration detection unit is temporarily stopped and then repeated to start power supply, and the number of times abnormality information is output is counted. A method for diagnosing an acceleration detection unit, comprising: determining that the acceleration detection unit is out of order when the number of times reaches a preset number.

Images