JP4037115B2 - Multiple communication device and vehicle occupant protection device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multiplex communication apparatus that performs multiplex communication between a plurality of slave units and a master unit, and a vehicle occupant protection apparatus using the same.
[0002]
[Prior art]
Conventionally, as an airbag control apparatus (generally referred to as a side airbag system) capable of handling a side collision, for example, there is a configuration as shown in FIG. 10 and FIG. explain.
That is, the airbag control device includes a center unit (master unit) 3 serving as a master station mounted on the tunnel floor of the vehicle 1 and a satellite sensor (slave serving as a slave station mounted below the left and right center pillars. Unit) 5a, 5b, side airbag 9a accommodated in the backrest side of the driver's seat 7a, side airbag 9b accommodated in the backrest side of the passenger seat 7b, and the meter unit 2 of the instrument panel The airbag warning light 4 is provided.
The center unit 3 shown in FIG. 11A includes a CPU 3a, a safing sensor 3b, and output circuits 3c and 3d. The CPU 3a controls the entire system according to a control program stored in an internal ROM. Further, an airbag warning light 4 provided in the meter unit 2 of the instrument panel is connected to the CPU 3a.
[0003]
The output circuits 3c and 3d supply power to the side airbags 9a and 9b connected thereto in response to a deployment signal from the CPU 3a to deploy the side airbags 9a and 9b individually.
[0004]
Next, the satellite sensors 5a and 5b have a CPU 5aa and a G (acceleration) sensor 5bb as shown in FIG. 11B, and the CPU 5aa communicates with the master unit 3 according to a control program stored in the internal ROM. In addition to controlling communication, it is determined whether or not the side airbag should be deployed at the time of a vehicle collision based on an acceleration signal indicating deceleration from the G sensor 5bb, and the determination result is transmitted to the CPU 3a of the center unit 3. Instructing the output of the development signal from the CPU 3a.
[0005]
However, in recent years, there has been a strong demand for weight reduction of vehicles from the viewpoint of environmental protection, in contrast to the configuration described above. Against this background of the times, there has been a strong demand for a system with a further multiplex communication configuration for the harness wiring structure.
[0006]
Therefore, in general, there can be considered a multiplex communication configuration in which the center unit 3 and the plurality of satellite sensors 5a and 5b have a ring connection configuration disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-217754, “Communication System”. .
[0007]
[Problems to be solved by the invention]
However, in the prior art shown in the prior art, the annular communication line is doubled, and normally the signal is transmitted to one of the communication lines in one direction and the other communication line. That is, when monitoring data is sent to the monitoring information transmission line and a failure occurring on the downstream side of each node is detected, a circuit configuration that bypasses the node is constructed so that communication is always possible.
Therefore, there is a problem that the structure is complicated and the cost is increased.
[0008]
Therefore, the present invention has been made to solve the above-described problems. When a failure occurs, the ring communication line is single, and when a failure occurs, the left and right directions, that is, clockwise ( It is an object of the present invention to provide a unit that can transmit signals to all slave units in the clockwise direction or counterclockwise direction (counterclockwise).
[0009]
[Means for Solving the Problems]
The present invention provides a multiplex communication apparatus comprising a master unit and a plurality of slave units, wherein the master unit and the plurality of slave units are connected in a ring shape by signal lines, and each unit is provided with a microcomputer.
When the microcomputer of the master unit determines that any communication failure has occurred in either the signal line or the plurality of slave units, it is transmitted clockwise or counterclockwise on the signal line. With a signal transmission direction switching function that switches and supplies output signals, Each of the plurality of slave units includes first switch means interposed in series with the signal line, and second and third switch means whose one ends are separately connected to both terminals of the first switch means. In addition, an input / output port of each microcomputer of the plurality of slave units is connected to the other end of each of the second and third switch means, and each of the microcomputers has a first switch means in its initial setting. And any one of the second or third switch means can be switched to an on state. In this way, a multiplex communication circuit can be formed in a short time and surely by switching the first switch to the ON state after switching either the second or third switch means to the ON state.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
This embodiment relates to an embodiment of the present invention as shown in FIG. 1, and is a diagram showing a system configuration of an airbag control device (vehicle occupant protection device).
[0013]
That is, 10 is a master unit, 11 is a first satellite unit (for example, a driver's seat side acceleration sensor unit), 12 is a second satellite unit (for example, a driver side airbag deployment drive circuit), and 13 is a third satellite unit (for example, (Passenger seat side acceleration sensor unit), 14 is a fourth satellite unit (for example, side airbag deployment drive circuit for passenger seat), 16 is a switching control function section (this switching control function section 16 is a separate circuit from the master unit 10 in the figure) Although it is described as a block, it actually constitutes a part of the master unit 10), and the first to fourth satellite units 11 to 14 and the switching control function unit 16 are connected by a single communication line 15. It is electrically connected in a ring to form a voltage multiplex communication configuration. This communication line 15 (connected in series) And a signal line 15a to 15e.) Is supplying from said master unit 10 includes various kinds of signals (data to the first to fourth satellite units) and power by. That is, the communication line 15 serves as a signal line as a power line.
The first to fourth satellite units 11 to 14 form a slave unit.
[0014]
Next, the detailed configuration will be described in the order of the master unit 10, the switching control function unit 16, and the first to fourth satellite units 11-14.
First, the master unit 10 is slightly different from the center unit 3 in the conventional example, but is substantially the same function, that is, a microcomputer having a collision determination function unit 10a, a diagnosis function unit 10b, and a multiplex communication function unit 10c, a power circuit 10d, The diagnostic function unit 10b and the multiplex communication function unit 10c are connected to the communication line 15a via the first line switching function unit 16a of the switching control function unit 16, and are also configured as a second line. It is connected to the communication line 15e via the switching function part 16b.
[0015]
Next, the switching control function unit 16 includes a microcomputer provided with a first line switching function unit 16a, a second line switching function unit 16b, a command issuing function unit 16c, and the like, and a DC power supply 16d that supplies power to the microcomputer. The command issuing function unit 16c is configured to select the first line switching function unit 16a or the second line switching function unit 16b based on instructions from the collision determination function unit 10a and the diagnosis function unit 10b of the master unit 10. When the power is turned on based on an instruction from the master unit 10 via the activated first line switching function unit 16a or the second line switching function unit 16b, the first line switching function unit 16a or the second line switching function unit 16b to the DC output from the power supply circuit 10d to the activated one of the first to fourth satellites. Allowed to superimpose a signal for supplying the address and various request signals to the respective site units 11-14.
[0016]
Further, after activating the first line switching function unit 16a, the command issuing function unit 16c executes the initial setting process A in the flowchart shown in FIG. The normal communication process C is advanced.
[0017]
Further, the command issuing function unit 16c determines that, in the initial setting process A, if there is a communication failure in the communication line 15 or any of the first to fourth satellite units 11-14, the master unit 10 If the diagnosis function unit 10b determines, the first line switching function unit 16a is deactivated based on an instruction from the diagnosis function unit 10b of the master unit 10 and at the same time the second line switching function unit 16b is activated, and the flowchart shown in FIG. Then, the initial setting process A, the communication failure detection process B, the normal communication process C, the communication abnormality occurrence part detection D, the communication abnormality occurrence part disconnection, and the communication reconstruction E are advanced.
[0018]
Furthermore, when it is determined that a communication failure has occurred in the communication line 15 or any of the first to fourth satellite units 11 to 14 during normal communication, the command issuing function unit 16c Based on the instruction of the diagnostic function unit 10b, for example, the first line switching function unit 16a is deactivated and the second line switching function unit 16b is activated at the same time, and the initial setting process A and the communication failure detection process B are performed according to the flowchart shown in FIG. The normal communication process C, the communication abnormality occurrence part detection D, the communication abnormality occurrence part disconnection, and the communication reconstruction E are advanced.
Conversely, when the second line switching function unit 16b is deactivated, the first line switching function unit 16a is activated at the same time.
[0019]
Next, the first satellite unit 11 includes a first bus switch (first switch means) 11a, a first control switch (second switch means) 11b, a second control switch (third control switch means) 11c, A line voltage monitoring circuit 11d, a second line voltage monitoring circuit 11e, a first interface 11h, a command decoding circuit (consisting of a microcomputer) 11f, a first DC power supply 11g, etc., and the first bus switch 11a Are inserted between the communication lines 15a and 15b connected in series. The first control switch 11b and the second control switch 11c are connected in series and are connected in parallel to the first bus switch 11a in the state of being connected in series.
[0020]
The first line voltage monitoring circuit 11d monitors the voltage of the signal line 15a connected to one of the two input / output terminals of the first satellite unit 11, and The first control switch 11b is turned on by detecting the fall of the voltage of the first address signal output from the command issuing unit 16c and voltage-multiplexed to a constant voltage after the operation of the power supply circuit 10d is started.
[0021]
The second line voltage monitoring circuit 11e is connected to the other input / output terminal of the first satellite unit 11, and the communication line 15 generated after the operation of the power supply circuit 10d of the master unit 10 is started. When the communication failure occurs in any of the fourth satellite units 11 to 14, the voltage of the signal line 15b after the reset of the first to fourth satellite units 11 to 14 is monitored, and the instruction of the switching control function unit 16 Thus, the falling of the voltage of the first address signal voltage-multiplexed on the signal line 15b is detected, and the second control switch 11c is turned on.
[0022]
The first interface 11h has an input / output terminal connected to a connection point of the first and second control switches 11b and 11c connected in series, receives an address signal and a request signal from the communication line 15, and receives them. A response signal and an airbag deployment request signal output from the first command decoding circuit 11f are output to the communication line 15 while being supplied to the first command decoding circuit 11f.
[0023]
When the address signal is supplied, the first command decoding circuit 11f sends its own unit and the other second to fourth satellite units 12 to 14 to the master unit 10 and the switching control function unit 16. As a unique address signal to distinguish memory 11i is stored and initialized, and the first bus switch 11a is turned on.
[0024]
The first command decoding circuit 11f always performs self-diagnosis of its unit, and when a request signal is supplied, outputs the result of the self-diagnosis to the first interface 11h. If the diagnosis result is a self-circuit, that is, in this case, it is determined that a communication failure has occurred in the first satellite unit 11, the first bus switch 11a, the first control switch 11b, and the second control switch 11c are turned on. The address stored in the memory 11i is discarded, and the second DC power supply 11g is forcibly disabled, and the electric charge accumulated in the capacitor constituting the second DC power supply 11g is discharged. Disable restart and completely eliminate the possibility of malfunctions. That is, initial setting is performed.
[0025]
The third satellite unit 13 has the same configuration as the first satellite unit 11, and each first bus switch (first switch means) 13 a corresponds to the first bus switch 11 a of the first satellite unit 11. The first control switch (second control switch means) 13 b corresponds to the first control switch 11 b of the first satellite unit 11, and the second control switch (third switch means) 13 c is the first satellite unit 11 of the first satellite unit 11. The first line voltage monitoring circuit 13d corresponds to the second control switch 11c, the first line voltage monitoring circuit 11d corresponds to the first satellite unit 11, and the second line voltage monitoring circuit 13e corresponds to the first satellite unit 11. The first interface 13f corresponds to the second line voltage monitoring circuit 11e and the first satellite unit 11 has a first interface. The command decoding circuit 13g corresponds to the first command decoding circuit 11f of the first satellite unit 11, and the second DC power supply 13h corresponds to the second DC power supply 11h of the first satellite unit 11. .
[0026]
The second and fourth satellite units 12 and 14 also have basically the same configuration as the first satellite unit 11, and each of the first bus switches (first switch means) 12a and 14a has a first configuration. Each of the first control switches (second switch control) 12b and 14b corresponds to the first control switch 11b of the first satellite unit 11, and corresponds to the second control switch (second switch control). (Third switch means) 12c, 14c corresponds to the second control switch 11c of the first satellite unit 11, and each of the first line voltage monitoring circuits 12d, 14d is the first line voltage of the first satellite unit 11. The second line voltage monitoring circuits 12e and 14e correspond to the monitoring circuit 11d, and the first satellite unit 11 Each of the first interfaces 12f and 14f corresponds to the first interface 11f of the first satellite unit 11, and each of the command decoding circuits 12g and 14g corresponds to the first satellite unit 11. And the second DC power supplies 12h and 14h correspond to the second DC power supply 11h of the first satellite unit 11, respectively.
[0027]
However, the difference between the first and third satellite units 11 and 13 and the second and fourth satellite units 12 and 14 is that acceleration sensors 11j and 13j are connected to the first and third satellite units 11 and 13, respectively. In the second and fourth satellite units 12 and 14, squibs 12j and 14j are connected in place of the acceleration sensors 11j and 13j.
[0028]
Next, an outline of control of the master unit 10 with respect to the switching control function unit 16 is shown in a flowchart of FIG. 4, and detailed flowcharts of respective blocks in the flowchart are shown in FIGS.
[0029]
First, an overview of the communication function of the master unit 10 will be described based on the flowchart shown in FIG.
First, after performing the initial setting process step A when the power is turned on, the process proceeds to the next step B.
First, in step B, communication failure detection processing is performed to detect whether a communication failure has occurred. If it is determined that no communication failure has occurred, normal communication processing is performed in next step C. If it is determined in step B that a communication failure has occurred, a communication failure part detection process is performed in the next step D, an abnormal part is determined, and in step E, the communication failure part, that is, A communication failure site disconnection process and a communication network reconfiguration process for disconnecting the abnormal part from the multiplex communication link are performed, and the process proceeds to the normal communication process of Step C. When step C ends, the process returns to step B again, and the above steps C, D, and E are repeatedly executed.
[0030]
Hereinafter, each of these steps will be described.
(Initial setting process)
Next, detection of communication failure occurrence in the initial setting process in step A of FIG. 4 will be described.
When the process proceeds to step A of the initial setting process, the first line switching function unit 16a is activated by the command issuing function unit 16c, while the second line switching function unit 16b is deactivated and the signal line 15a is activated. The address and request signal of the first satellite unit 11 are output, and a response signal indicating that the communication circuit is normal from the first satellite unit 11 for the request signal is confirmed. The same operation as the confirmation operation is performed in order for each of the second to fourth satellite units 12 to 14 in order to diagnose whether or not there is a communication failure, and the process proceeds to the next step B.
[0031]
That is, for communication between the master unit 10 and the first to fourth satellite units 11 to 14, a predetermined time T per frame is given as a set value as shown in FIGS. The one frame basically includes an address signal portion, a request signal portion, a response signal portion, and first to fourth satellite emergency communication area portions.
[0032]
Next, a specific description will be given based on the flowchart shown in FIG.
First, when the power is turned on, in step A, the command issuing function unit 16c outputs an output signal (address signal, request signal) from the command issuing function unit 16c in a clockwise direction (A direction shown in FIG. 1), for example. For transmission, only the first line switching function unit 16a is activated based on an instruction from the command issuing function unit 16c (step ST210), and when the first line switching function unit 16a is normally activated, The address signal and the request signal are output in order from the first satellite unit 11 to the fourth satellite unit 14, but here, the initial setting process of the same contents is performed from the first to the fourth satellites 11 to 14, so the first satellite unit 11 This will be described below as a representative. First, a response signal indicating that the communication circuit from the first satellite unit 11 is normal with respect to the request signal output in step ST220 is confirmed. When it is determined that the communication is normally possible, a signal indicating that is supplied to the diagnostic function unit 10b of the master unit 10, and the process proceeds to step ST230 of step B.
[0033]
On the other hand, when the diagnostic function unit 10b determines that a signal indicating that communication is not normally performed is not confirmed even after waiting for a predetermined time (steps ST220 and 240), an output signal (address) from the command issuing function unit 16c. For example, the diagnostic function 10b inactivates the first line switching function unit 16a with respect to the command issuing function unit 19 in order to transmit the signal (request signal) in the counterclockwise direction (direction B shown in FIG. 1). And instructing to activate the second line switching function unit 16b instead (step ST260). Then, the diagnosis similar to that in the case of the first line switching function unit 16a is performed in the reverse order as shown in FIG. 5B, that is, the fourth satellite unit 14, the third satellite unit 13, the second satellite unit 12, The second line switching function unit 16b is also performed in the order of the first satellite unit 11.
[0034]
Next, in step ST230, the command issuing function unit 16c causes the first line switching function unit 16a to superimpose an address signal and a request signal for communicating with the first satellite unit 11 on the power supply voltage. In step ST270, it is determined whether the first line voltage monitoring circuit 11d of the first satellite unit 11 has received an address and a request signal from the communication line 15a, and the address signal and the request signal are received. If it is determined based on the response signal, the process proceeds to step ST280.
[0035]
On the other hand, if it is determined in step ST270 that the address signal and the request signal have not been received, steps ST270 and ST290 are repeatedly executed and waited until a predetermined time elapses. If it is determined that it has not been received even after the predetermined time has elapsed, the process proceeds to step ST300. In step ST300, the command issuing function unit 16c instructs the diagnostic function unit 10b to inactivate the first line switching function unit 16a (step ST300), and proceeds to step ST260. An instruction for activating the unit 16b is given.
[0036]
When the first circuit voltage monitoring circuit 11d receives the first voltage change of the signal indicating the address in step ST270, the first control switch 11b is turned on in step ST280, and the address signal and the request signal are sent to the first command decoding circuit 11f. Supplied.
[0037]
If the address signal and the request signal supplied to the first command decoding circuit 11f are normally decoded and the address signal is stored in the memory 11i, the process proceeds to step ST310 to confirm that the decoding and storage are normally performed. The response signal shown is output from the first command decoding circuit 11f to the communication line 15a via the first interface 11h, returned to the diagnosis function unit 10b of the master unit 10, and the response signal is received by the diagnosis function unit 10b. If it is determined, the process proceeds from step ST310 to step ST320.
[0038]
However, if there is no response signal, it waits for a predetermined time in step ST330. If it still does not come, a signal indicating the occurrence of communication failure is supplied to the diagnostic function unit 10b (step ST340), and the command issuing function unit 16c The diagnostic function unit 10b instructs the first line switching function unit 16a to be deactivated (step ST350), and all the switches 11a to 14a, 11b to 14b, 11c to the first to fourth satellite units 11 to 14 are instructed. An instruction to turn off 14c, 11d to 14d is issued (step ST380), and the process proceeds to step ST260.
[0039]
If the address signal is stored in the memory 11i in step ST310 and the process proceeds from step ST310 to step ST320, a signal for turning on the first bus switch 11a of the first satellite unit 11 is sent to the command generation circuit in step ST320. By instructing the first line switching function unit 16a from 16, it is required that an address signal and a request signal indicating it are output from the first line switching function unit 16a to the communication line 15, but the first satellite unit 11 The first command monitoring unit 26 recognizes this, turns on the first bus switch 11a, and when the diagnostic function unit 10b confirms that the first bus switch 11a is turned on (step ST390), The second satellite indicated by step A ′ block C shown in FIG. Proceed to the flowchart of the initial setting process of the unit 12.
[0040]
The flowchart of step A ′ performs the same operation as step A performed for the first satellite unit 11.
On the other hand, in step ST390, a response signal is output from the first command decoding circuit 11f to the communication line 15a via the first interface 11h, returned to the diagnostic function unit 10b of the master unit 10, and is transmitted by the diagnostic function unit 10b. If there is no response signal after waiting for a predetermined time in step ST400 and still does not come, it is determined that a communication failure has occurred (step ST410), and the command issuing function unit 19 performs the first line switching function by the diagnostic function unit 10b. The unit 16a is inactivated (step ST420), and in the next step ST430, all the switches 11a to 11e, 12a to 12e, 13a to 13e, and 14a to 14e of the first to fourth satellite units 11 to 14 are used. Outputs an instruction to turn off, and then proceeds to step ST260
[0041]
Thereafter, as described above, the process proceeds to step A ′ in FIG. 8 to perform the initial setting process of the second satellite unit 12. When this is completed, the process proceeds to step A ″ block D in FIG. 8 to initialize the third satellite unit 13. Similar steps are performed when the process proceeds to the setting process, or when the initial setting process of the third satellite unit 14 is completed and the process proceeds from the third satellite unit 13 to the step A ′ ″ of the initial setting process of the fourth satellite unit 14. Are executed in order, and when they are completed normally, the communication failure detection process of step B in FIG. 4 is entered.
[0042]
However, as described above, if the initial setting process for performing communication in the order of the first, second, third, and fourth satellite units 11 to 14 could not be performed, the reverse direction, that is, the first line switching function unit. 16a is deactivated and the second line switching function unit 16b is activated, and communication is performed in the order of the fourth, third, second, and first satellite units 14 to 11 as shown in FIG. 5B. Setting is performed and normal communication is started, but when both the first and fourth satellite units 11 and 14 have communication failures, initial setting is not performed and communication is disabled.
The communication failure detection process is performed by recognizing a part that is determined to be unable to communicate by performing the same process as that performed in the initial setting process (step A in FIG. 4).
[0043]
(Normal communication processing)
Next, when it is determined that the communication is normally performed as a result of the initial setting process, the normal communication process (step C in FIG. 4) described below is performed according to the flowchart based on FIG.
This is the same communication method as the communication at the time of star connection in multiplex communication, and the details will be described below.
[0044]
Normally, the master unit 10 starts operating in a state where the first line switching function unit 16a is activated and the second line switching function unit 16b is deactivated as the power is turned on by turning on the ignition switch. Then, the process proceeds to step ST500, in which the multiplex communication function unit 10C is arranged in the order of the first, second, third, and fourth satellite units 11 to 14 with respect to the communication line 15a. The address signal, the request signal, the response signal, and the development request address writing area shown in FIG. 1 are communicated in one frame. The satellite unit to be subjected to this communication is designated by the address supplied to the communication line 15a this time.
[0045]
That is, if the supplied address signal matches the address signal stored in the memory 11i of the first satellite unit 11 in the initial setting (step ST510), the multiplex communication function unit 10C 11, and if it matches the address signal stored in the memory 12 i of the second satellite unit 12 (step ST 510), the multiplex communication function unit 10 C communicates with the second satellite unit 12.
The same applies to the third and fourth satellite units 13 and 14.
[0046]
Next, as a representative example, communication between the diagnostic function unit 10b and the first and second satellite units 11 and 12 will be described.
First, in the first satellite unit 11, for example, the request signal of the first frame shown in FIG. 5A, that is, the request signal shown in FIG. 5C is supplied to the first satellite unit 11, and the first command decoding circuit 11f decodes the request signal and sends a response signal (see FIG. 5C) to the request signal from the first satellite unit 11 to the diagnostic function unit 10b via the communication line 15a and the multiplex communication function unit 10C. When supplied, the diagnosis function unit 10b diagnoses whether there is a communication failure in the first satellite unit 11 and its communication line 15a.
[0047]
This diagnosis is also performed on the second satellite unit 12 in the same manner, and is supplied from the multiplex communication function unit 10C to the diagnosis function unit 10b to diagnose whether there is a communication failure.
In addition, in the initial setting process shown in step A of FIG. 7, when the predetermined time has not been taken with the first line switching function unit 16a (step ST520), the process proceeds to step ST530. The two-line switching function unit 16b is activated and the first line switching function unit 16a is deactivated. When the master unit 10 starts operating in this state, communication is performed in the order of the fourth, third, second, and first satellite units 14 to 11 (step ST540).
[0048]
(Communication at the time of collision in the above normal communication)
Next, the description proceeds to the communication with the second satellite unit 12.
For example, when communication is being performed between the diagnostic function unit 10b and the first satellite unit 11 in the (normal communication processing), for example, the third satellite unit 13 is located on the side of the vehicle at time X in FIG. A case where it is detected that a collision has occurred from the (left and right) direction will be described below as an example.
[0049]
That is, for example, the third satellite unit 13 collides from the lateral direction of the vehicle at time X within the time when the request signal and the response signal are being communicated between the diagnostic function unit 10b and the first satellite unit 11. Is detected by the lateral acceleration sensor 13j, the third command decoding circuit 13f of the third satellite unit 13 enters the specific third satellite emergency communication area designated from the lateral direction as shown in FIG. Collision data for notifying that a collision has occurred has been written (shaded area in FIG. 5D).
[0050]
When the collision determination function unit 10a of the master unit 10 receives the collision data written in the specific area, the collision determination function unit 10a subsequently communicates with the second satellite unit 12 in the YY ′ section. In order to start the multiplex communication with the third satellite unit 13 that has transmitted the data indicating the occurrence of the collision without jumping, the address shown in the first section T ′ of FIG. A signal and a request signal are supplied through the communication lines 15c to 15a.
[0051]
As a result, the command decoding function unit of the third satellite unit 13 13f Supplies a response signal indicating the occurrence of a collision to the collision determination function unit 10a via the communication lines 15c to 15a and the first line switching function unit 16a. The collision determination function unit 10a is connected to the third satellite unit 13. When a collision is determined as a result of comparing the fact that the collision has been detected with other deployment conditions, a fourth satellite unit for deploying a side airbag provided in a pair with the third satellite unit 13 14, a request signal for attaching the address of the fourth satellite unit 14 and instructing squib ignition (corresponding to an address signal and a request signal shown in the second section T ′ from the left in FIG. 5D) Is supplied via the signal lines 15a to 15d, the fourth satellite unit 14 supplies an ignition signal to a squeeze (not shown), After the expansion, the expansion end data is returned to the multiplex communication function unit 10C as a response signal.
[0052]
As a result, the fourth command decoding circuit 14f of the fourth satellite unit 14 reads the request signal instructing the squib ignition via the communication lines 15a to 15d, and when the request is decoded, supplies the ignition current to the squib. Then deploy the side airbag.
[0053]
When it is determined in the above (normal communication processing) that a communication failure has occurred during communication between the multiplex communication function unit 10C of the master unit 10 and the first to fourth satellite units 11 to 14, FIG. Proceed to the flowchart (the communication failure detection process in step D, the communication failure part disconnection process and the reconstruction process in step E).
[0054]
(Communication failure detection processing, communication failure site disconnection processing, and reconstruction processing)
These functions are performed in order for each of the first satellite unit 11, the second satellite unit 12, the third satellite unit 13, and the fourth satellite unit 14, and the contents to be performed are the same. The following is representatively performed for only one satellite unit 11. This process is for steps D and E in FIG.
[0055]
First, the entire flowchart will be described, and then a specific example thereof will be described.
In FIG. 9, in step ST500, the command issuing function unit 16c causes the first line switching function unit 16a to output the address signal and request signal of the first satellite unit 11 to the communication line 15, and a response signal for the request signal. Is returned during a predetermined time (steps ST510 and 520). If it is determined in step ST520 that the predetermined time has elapsed, in step ST530, the diagnostic function unit 10b determines that a communication failure has occurred with the first satellite unit 11, and issues the command. The diagnostic function unit 10b outputs an instruction signal for turning off the first bus switch 11a to the function unit 16c, the first bus switch 11a is turned off, and the first satellite unit 11 is reset in subsequent step ST540. By turning off the other control switches 11b and 11c. In FIG. Step E Proceed to the disconnection and reconstruction process of the communication failure occurrence site.
[0056]
If it is determined that the diagnostic function unit 10b has received the response signal, the process proceeds to the next block, and the second satellite unit 12 performs the same signal processing as described above, and further performs the third satellite unit 13 and the fourth satellite unit 4. Proceed to satellite unit 14.
[0057]
Next, a specific example will be described with reference to FIG.
That is, the diagnostic function unit 10b performs normal normal communication with the first satellite unit 11 (part of FIG. 6A), and then the address of the second satellite unit 12 with respect to the second satellite unit 12. A signal and a request signal are output, and a response signal cannot be received (the shaded area in FIG. 6B), and a communication failure occurs in the second satellite unit 12 by the diagnostic function unit 10b of the master unit 10. If it is determined, the second satellite unit 12 is supplied with a request signal for turning off the second bus switch 12a, the third control switch 12b, and the third control switch 12c (FIG. 6 ( c), the second bus switch 12a, the third control switch 12b, and the third control switch 12c are turned off.
[0058]
Thereafter, the command issuing function unit 16c deactivates the first line switching function unit 16a, activates the second line switching function unit 16a, and performs the initial setting process (FIG. 6D). ) (S section)), normal communication processing is performed (U section in FIG. 6 (e)).
That is, in order to start communication with the other first satellite unit 11, the third satellite unit 13, and the fourth satellite unit 14 excluding the second satellite unit 12, the switching control function unit 16 has been The second line switching function unit 16b, which has not been activated, is activated instead of the first line switching function unit 16a, and the fourth satellite unit 14, the third satellite unit 13, the second satellite unit 12, and the first satellite unit are activated. The initial setting process as described above is performed in the order of 11, but before that, all of the first to fourth satellite units 11 to 14 are reset, the address signals stored in the memories 11i to 14i are discarded, and the first By outputting a request signal for turning off all the first to fourth bus switches 20 and the first to eighth control switches 21 to 28. Te, the entire circuit system is reconstructed, first, performs processing according to the flowchart shown in FIG. 4 with respect to the third and fourth satellite units 11, 12, 14, to rebuild.
[0059]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
(1) Even one annular communication line has substantially two communication circuits against communication failure, and reliability can be improved.
(2) Further, when a communication failure occurs, “abnormal part detection → abnormal part disconnection → normal recovery” can be performed for all abnormalities (disconnection, ground fault, power supply short circuit), and reliability can be improved.
(3) A special dedicated line for strengthening the communication line abnormality is not necessary and does not increase the cost.
(4) Further, when this is applied to a vehicle occupant protection device, the vehicle occupant protection device can be obtained at a low cost, so that the vehicle occupant protection device can be mounted on a low-price vehicle.
[Brief description of the drawings]
FIG. 1 shows one part of an overall circuit block of a vehicle occupant protection device using a multiplex communication circuit, that is, a master unit 10, a switching control function unit 16, and a first satellite according to an embodiment of the present invention. It is explanatory drawing which shows the connection state of the unit.
FIG. 2 is an explanatory view showing a connection state of second and third satellite units 12 and 13 connected to the portion shown in FIG.
FIG. 3 is an explanatory diagram showing a connection state of a fourth satellite unit 14 connected to the portion shown in FIG. 2;
FIG. 4 is a flowchart for explaining the general operation of the apparatus shown in FIGS.
FIG. 5 is a time chart for explaining the operation of FIGS. 1 to 3;
6 is a flowchart at the time of initial setting of the apparatus shown in FIGS. 1 to 3 based on FIG. 5;
FIG. 7 is a normal flowchart of the apparatus shown in FIG. 1;
FIG. 8 is a flowchart following FIG. 7;
FIG. 9 is a flowchart in a normal state of the apparatus shown in FIGS.
FIG. 10 is an overall schematic explanatory view of a conventional driver's seat side airbag unit.
11 is a circuit block diagram of the center unit 3 and the Sate light unit of FIG.
[Explanation of symbols]
10 Master unit
10a Collision judgment function part
10b Diagnostic function section
10c Multiplex communication function part
10d power circuit
11-14 Satellite unit
11a, 12a, 13a, 14a Bus switch
11b, 11c, 12b, 12c, 13b, 13c, 14b, 14c Control switch
11d, 11e, 12d, 12e, 13d, 13e, 14d, 14e Line voltage monitoring circuit
11f, 12f, 13f, 14f Command decoding circuit
11g, 12g, 13g, 14g DC power supply
11h, 12h, 13h, 14h interface
11i, 12i, 13i, 14i memory
10e, 11j, 13j Acceleration sensor
12j, 14j squib
15, 15a-15d Communication line
16 Switching control function part
16a, 16b Line switching function section
16c Command issuing function
16d DC power supply

Claims (2)

In a multiplex communication apparatus comprising a master unit and a plurality of slave units, wherein the master unit and the plurality of slave units are connected in a ring shape by signal lines, and each unit is provided with a microcomputer.
When the microcomputer of the master unit determines that any communication failure has occurred in either the signal line or the plurality of slave units, it is transmitted clockwise or counterclockwise on the signal line. A signal transmission direction switching function for switching and supplying an output signal is provided, and each of the plurality of slave units is separately provided at a first switch means inserted in series with the signal line and at both terminals of the first switch means. Second and third switch means connected at one end, and input / output ports of the microcomputers of the plurality of slave units are connected to the other ends of the second and third switch means, Each of the microcomputers has a first switch means and the second or third switch in its initial setting. Multiplex communication system according to this and the features which are switched one of means to the ON state. In the initial setting, the microcomputer switches to the on state of the first to third switch means after switching either the second or third switch means to the on state and then turning on the first switch. 2. The multiplex communication apparatus according to claim 1 , wherein the multiplex communication apparatus is switched to.

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