JP4298314B2 - Airbag device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an airbag device for protecting an occupant at the time of a car collision or the like.
[0002]
[Prior art]
Conventionally, an air bag system has been used to protect an occupant in the event of a car collision. In the airbag system, when a large impact acceleration is detected, for example, the airbag is rapidly inflated between the steering wheel and the driver and deployed to mitigate the impact. In order to rapidly inflate an air bag, gas is explosively generated by an ignition device called a squib. However, if the airbag inflates during normal operation, it will hinder the operation, so the ignition of the squib is surely performed using both mechanical impact detection and electronic impact detection. (For example, see Patent Document 1 and Patent Document 2).
[0003]
FIG. 5 shows a schematic electrical configuration of an airbag apparatus basically equivalent to that disclosed in Patent Document 1. Ignition for deploying the airbag is performed by energizing the squib 1.
[0004]
A mechanical condition for energizing the squib 1 is detected by the trigger GSW2. The trigger GSW2 is a switch (SW) that mechanically detects an impact using the acceleration G of gravity as a unit and conducts the contact while exceeding a predetermined acceleration G. The trigger GSW2 has a weight and a spring inside, and when the weight is displaced according to the acceleration of the impact, the electrical contact is closed and becomes conductive. G represents acceleration.
[0005]
Electronic condition detection is performed by the G sensor 3. The G sensor 3 also has a weight inside, and when the weight is displaced according to the acceleration of impact, it is converted into an electric signal by various principles such as a strain gauge type, a capacity type, a piezoelectric type, an electrodynamic type, and a servo type ( For example, refer nonpatent literature 1).
[0006]
The squib 1 is electrically driven by an ASIC (Application Specific Integrated Circuit) 4. However, the determination of the electronic shock detection result by the G sensor 3 is performed by a CPU (processing circuit) 5. The CPU 5 processes the detection output from the G sensor 3 according to a preset program, and gives a control signal indicating condition detection to the ASIC 4 when a predetermined impact is detected. The ASIC 4 is a semiconductor integrated circuit for a specific application, and the same configuration can be realized by combining individual semiconductor elements and electronic components. However, once the ASIC 4 is made into a semiconductor integrated circuit, it can be downsized and highly reliable. In addition, a mass production effect can be expected.
[0007]
The ASIC 4 includes a determination circuit 10, transistors 11 and 12 that control energization of the squib 1, and a transistor 13. A transistor 11 shown as Q1 is, for example, an N-channel MOS (metal oxide film field effect) transistor, and has a drain connected to the positive side of the ignition power source and a source connected to one end side of the squib 1. That is, the transistor 11 is connected to the high side of the squib 1. The transistor 12 shown as Q2 is also an N-channel MOS transistor, with the drain connected to the other end of the squib 1 and the source connected to the ignition power source. That is, the transistor 12 is connected to the low side of the squib 1. An output from the CPU 5 is given to the low-side transistor 12. The gate of the transistor 11 on the high side is connected to the collector of a transistor 13, which is a PNP bipolar transistor, for example, indicated as Q3. The emitter of the transistor 13 is connected to the positive side of the ignition power source together with the drain of the transistor 11. The determination result of the determination circuit 10 is input to the base of the transistor 13. In the determination circuit 10, a time holding circuit for holding the detection state of the trigger GSW2 is provided for multistage deployment of the airbag.
[0008]
[Patent Document 1]
JP-A-9-20205
[Patent Document 2]
JP 2001-239916 A
[Non-Patent Document 1]
By Hiroo Yamazaki, “The Story of Sensors”, Nikkan Kogyo Shimbun, January 10, 1991, p. 87-89
[0009]
[Problems to be solved by the invention]
In the airbag apparatus as shown in FIG. 5, electronic shock detection by the G sensor 3 and mechanical shock detection by the trigger GSW2 are used in combination to prevent malfunction. However, the conventional circuit configuration as shown in FIG. 5 has insufficient points as a safing function as described below.
[0010]
(1) Since the high-side transistor 11 is driven via a logic circuit such as a determination circuit 10 (including a time holding circuit) in the ASIC 4, a failure of the ASIC 4 causes the trigger GSW2 to be turned on / off. There is a risk of malfunction (false ignition).
[0011]
(2) Since the ON detection of the trigger GSW2 is performed by an electronic circuit in the ASIC 4, there is a risk of malfunction due to external noise (such as electromagnetic waves).
[0012]
Since the trigger GSW2 is merely a mechanical switch, the original operation is not affected by external noise or the like. However, the electronic circuit portion such as the determination circuit 10 may be affected by external noise. When there is a possibility of malfunction due to the influence of external noise, the determination circuit 10 and the CPU 5 need countermeasures against malfunction, and increase the manufacturing cost of the airbag device.
[0013]
An object of the present invention is to provide an airbag device capable of preventing malfunctions with a simple configuration and improving the determination function.
[0027]
[Means for Solving the Problems]
  BookThe inventionMechanical detection means that mechanically conducts contacts when an acceleration exceeding a predetermined level is applied, and an electrical signal corresponding to the applied acceleration is output.In the airbag device for energizing the squib for deploying the airbag, based on the detection result with the electronic detection means,
  First and second capacitors charged by power from a power source;
  When an acceleration of a predetermined level or more is applied, the mechanical detection means conducts a contact for changing the first capacitor and the second capacitor connected in parallel to a series connection, whereby the first A third capacitor charged by a voltage when the capacitor and the second capacitor are connected in series;
  The drive signal supplied from the third capacitor is supplied until the charge charged in the third capacitor is discharged and the voltage of the third capacitor drops below a predetermined value,And switching means that operates when it is determined that the vehicle is in a collision state based on the detection result of the electronic detection means,
  In the airbag device, the squib is energized when the switching means is in an operating state.
[0028]
  According to the present invention, the airbag device isWhen the acceleration exceeds a predetermined level, the contacts are mechanically connected.Mechanical detection means;Outputs electrical signals according to the applied accelerationIn order to energize the squib for deploying the airbag based on the detection result with the electronic detection means,1st to 3rdWith capacitor, SuSwitching means.When the first capacitor and the second capacitor are connected in series by conducting the contact that changes the first capacitor and the second capacitor that are connected in parallel to the serial connection.By power supply from the power sourceThe third capacitorCharged, Switching meansIs detected when the mechanical detection means detects a predetermined acceleration or more,ThirdA drive signal can be generated by discharging the capacitor.
  The switching means operates when a drive signal is supplied and it is determined that the vehicle is in a collision state based on the detection result of the electronic detection means, and energization of the squib is performed. By mechanical detectionThirdSince the squib is energized when the discharge of the capacitor and the electronic detection are performed simultaneously, the malfunction can be prevented with a simple configuration and the determination function can be improved. Further, since the drive signal is generated by discharging the capacitor, the airbag can be deployed for a longer period than the detection period of the mechanical detection means.
  Further, the present invention is based on the detection results of the mechanical detection means that mechanically conducts the contact when an acceleration of a predetermined level or more is applied, and the electronic detection means that outputs an electrical signal corresponding to the applied acceleration. In an airbag device that energizes a squib for deploying an airbag,
  First and second capacitors charged by power from a power source;
  When an acceleration of a predetermined level or more is applied, the mechanical detection means conducts a contact for changing the first capacitor and the second capacitor connected in parallel to a series connection, whereby the first A third capacitor charged by a voltage when the capacitor and the second capacitor are connected in series;
  The drive signal supplied from the third capacitor is supplied until the charge charged in the third capacitor is discharged and the voltage of the third capacitor drops below a predetermined value, and First switching means that operates when it is determined that the vehicle is in a collision state based on a detection result of the electronic detection means;
  A second switching means provided for each of the squibs in order to control energization for each of the plurality of squibs,
  When the first switching means is in an operating state and the second switching means is in an operating state, the squib corresponding to the second switching means in the operating state is energized. This is an airbag device.
  According to the present invention, the airbag device includes mechanical detection means for mechanically conducting contact when a predetermined acceleration or more is applied, and electronic detection means for outputting an electrical signal corresponding to the applied acceleration. In order to energize the squib for deploying the airbag based on the detection result, the first to third capacitors and the first and second switching means are provided. By conducting a contact for changing the first capacitor and the second capacitor connected in parallel to the series connection, when the first capacitor and the second capacitor are connected in series, power is supplied from the power source. The third capacitor is charged.
  The first switching means supplies the drive signal supplied from the third capacitor until the charge charged in the third capacitor is discharged and the voltage of the third capacitor drops below a predetermined value. It is activated when it is determined that the vehicle is in a collision state based on the detection result of the electronic detection means. The second switching means is provided for each of the squibs to control energization for each of the plurality of squibs, the first switching means is in an operating state, and the second switching means is in an operating state. If it is, the squib corresponding to the second switching means in the operating state is energized.
  As described above, when the discharge of the third capacitor by the mechanical detection and the electronic detection are simultaneously performed, energization to the plurality of squibs is performed simultaneously or individually, so that malfunction is prevented with a simple configuration. The determination function can be improved. Further, since the drive signal is generated by the discharge of the third capacitor, the airbag can be deployed for longer than the detection period of the mechanical detection means.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic electrical configuration of an airbag apparatus 20 according to an embodiment of the present invention. The air bag device 20 energizes and ignites a squib for deploying the air bag based on mechanical condition detection and electronic condition detection in order to protect a vehicle occupant under predetermined conditions. Although the illustration of the airbag itself is omitted, the airbag device 20 of the present embodiment can deploy one airbag in multiple stages. That is, when a plurality of, for example, two squibs 21a and 21b are provided and rapid deployment of the airbag is necessary, currents Ia and Ib necessary for ignition are simultaneously supplied to the two squibs 21a and 21b, and the squib is slow. When the deployment is better, the two squibs 21a and 21b are energized with a time difference. Hereinafter, when referring collectively to the plurality of squibs 21a and 21b, the reference number “21” is used.
[0036]
The trigger GSW22 functions as mechanical detection means that closes the contact point when the acceleration G of impact acting on the built-in weight is large, detects the mechanical condition, and conducts only when the condition is satisfied. The G sensor 23 outputs an electrical signal according to the acceleration of the impact acting on the built-in weight. The ASIC 24 functions as an ignition drive unit that drives the squib 21 to energize for ignition only when an electronic condition is satisfied and a drive signal is generated. The CPU 25 responds to the output from the G sensor 23, determines whether or not the electronic condition is satisfied, and performs control to enable the squib 21 to be driven from the ASIC 24 when determining that the electronic condition is satisfied. .
[0037]
  As drive signal generation means for generating an electrical drive signal in accordance with the conduction of the trigger GSW 22 that is mechanical detection means, a voltage doubler circuit that boosts the power supply voltage VS supplied from the DC power supply 30 by about twice is provided. The voltage doubler circuit includes three capacitors 31, 32 and 33, two resistors 34 and 35, and two diodes 36 and 37. If the trigger GSW22 is in the cut-off state, the first capacitor 31 indicated as C1 is charged from the DC power source 30 to the vicinity of the power supply voltage VS via the first diode 36 indicated by D1 and the first resistor 34 indicated by R1. Then, the second capacitor 32 shown as C2 is charged from the DC power supply 30 to the vicinity of the power supply voltage VS through the second resistor 35 shown as R2.
  If the trigger GSW 22 becomes conductive due to the detection of the impact, the first capacitor 31 and the second capacitor 32 are connected in series, and the connection portion between the first capacitor 31 and the cathode of the first diode 36 is connected. Generates a voltage about twice the power supply voltage VS. This voltage charges a third capacitor 33, denoted C3, through a second diode 37, denoted D2.
  If the resistance value of the first resistor 34 is small, the boosting time is shortened, so that the resistance value is relatively large. If the resistance value of the first resistor 34 is large, the time required for the first capacitor 31 to be charged to the power supply voltage VS becomes longer, but the vehicle starts running after the engine is started.DoCharging may be completed in the time until.
[0038]
  The trigger GSW 22 is in a conductive state only while a predetermined impact is generated, and then returns to a cutoff state. When the trigger GSW22 returns to the cutoff state, the voltage booster operation as the voltage doubler circuit stops, and the voltage at the connection portion between the cathode of the first diode 36 and the first capacitor 31 returns to the power supply voltage VS or lower. Second diode37Then, the terminal voltage of the third capacitor 33 on the cathode side is higher than the terminal voltage of the first capacitor 31 on the anode side, and the second diode37Is biased in the reverse direction, and the terminal voltage of the third capacitor 33 is on the ASIC 24 side.InOnly as a drive signal.
[0039]
In the ASIC 24, an N-channel MOS transistor 41a, indicated by Q2, is indicated by Q1, and is indicated by Q2 as a switching element whose source and drain are connected in series to the high side of the first squib 21a. As switching elements whose source and drain are connected in series on the low side, an N-channel MOS transistor 42a and a PNP bipolar transistor 43, indicated by Q3, for driving the gate of the transistor 41 are included. Further, the high-side and low-side sides of second squib 21b include N-channel MOS type transistors 41b and 42b as switching elements indicated by Q4 and Q5, respectively. The collector of the transistor 43 is commonly connected to the gates of the transistors 41a and 41b. The drains of the transistors 41a and 41b are commonly connected to the positive side of the ignition power source. The sources of the transistors 41a and 41b are connected to one ends of the squibs 21a and 21b, respectively. The drains of the transistors 42a and 42b are connected to the other ends of the squibs 21a and 21b, respectively. The sources of the transistors 42a and 42b are grounded in common. The negative side of the ignition power source and the negative side of the DC power source 30 are commonly grounded. Hereinafter, the transistors 41a and 41b; 42a and 42b serving as switching elements are collectively indicated by reference numbers “41” and “42”.
[0040]
The terminal voltage of the third capacitor 33 is applied to the emitter of the transistor 43. The base of the transistor 43 is connected to the emitter via a third resistor 44 indicated by R3. One end of a fourth resistor 45 indicated by R4 is connected to a connection portion between the base of the transistor 43 and the third resistor 44. A control signal S1 is given from the CPU 25 to the other end of the fourth resistor 45. The CPU 25 gives control signals S2 and S3 to the gates of the transistors 42a and 42b, respectively. A detection output is given to the CPU 25 from the G sensor 23.
[0041]
FIG. 2 shows an outline of normal operation of the airbag device 20 of FIG. When the DC power supply 30 is turned on at time t0, the trigger GSW22 is turned off and the terminal voltage of the capacitors 31, 32, 33 rises to almost the power supply voltage VS. If the vehicle starts running and an accident or the like occurs at time t1 and a large impact acceleration G occurs, the trigger GSW22 is turned on when the impact acceleration G exceeds G1. When the trigger GSW 22 is turned on, the first capacitor 31 and the second capacitor 32 are connected in series. Since each of the capacitors 31 and 32 is charged to the power supply voltage VS, a voltage nearly twice the power supply voltage VS is applied to the third capacitor 33 via the second diode 37. It is charged with this voltage. Even when the trigger GSW22 returns to OFF at time t4, the second diode 37 is biased in the reverse direction, and the high voltage generated in the third capacitor 33 does not return to the first capacitor 31 side.
[0042]
When the impact acceleration G exceeds the CPU determination level G2 at time t3, the CPU 25 shifts the control signal S1 serving as an ignition signal from OFF to ON. The time for which the control signal S1 is ON is a time sufficient for operating the squib 21. When the control signal S1 is turned ON, the emitter and collector of the transistor 43 become conductive, and the terminal voltage of the third capacitor 33 is connected between the emitter and collector of the transistor 43 by the transistors 41a and 41b (Q1, Q4). ) Is applied as the gate voltage VG. The gate voltage VG becomes higher than the ON possible voltage Vt, and the transistors 41a and 41b on the high side with respect to the squibs 21a and 21b are turned on and become conductive. Since the CPU 25 turns on the control signal S2 when the control signal S1 is ON and shifts the low-side transistor 42a to the ON state, the squib 21a is energized and the current Ia flows.
[0043]
In the present embodiment, as described above, even after the trigger GSW22 is turned off at time t4, for example, at time t5, the CPU 25 turns on the control signals S1 and S3 until the charge of the third capacitor 33 is discharged. Then, the transistors 41b and 42b (Q4 and Q5) on the squib 21b side can be turned on to energize and ignite the squib 21b. In this way, by providing a time difference in the ignition of the plurality of squibs 21a and 21b, the airbag can be deployed slowly. When the impact acceleration G detected by the G sensor 23 is large, the CPU 25 energizes both the squibs 21a and 21b simultaneously to rapidly deploy the airbag, or when the impact acceleration G is small, the CPU 25 moves to one squib 21a. It is also possible to keep only energization.
[0044]
In the present embodiment, the airbag device 20 is provided with a squib 21 for deploying an airbag based on mechanical condition detection and electronic condition detection in order to protect a vehicle occupant under predetermined conditions. In order to energize and ignite, a trigger GSW22 as mechanical detection means, a voltage doubler circuit as drive signal generation means, and an ASIC 24 as ignition drive means are included. The ignition drive means drives the squib 21 to energize for ignition only when the electronic condition is satisfied and a drive signal is generated. The ASIC 24 is energized for ignition if the electronic condition is satisfied only when a drive signal generated by the trigger GSW22 being conducted is supplied from the voltage doubler circuit, so that the trigger GSW22 is conducted. In the case of external noise that does not occur, even if it is erroneously determined that the electronic condition is satisfied, energization for ignition is not performed, and malfunction can be prevented. When the trigger GSW 22 is turned on, a drive signal is generated by the voltage doubler circuit, so that a reliable ignition can be performed with a simple configuration.
[0045]
Further, the power supply voltage of the ignition power supply and the power supply voltage of the DC power supply 30 applied to the drain of the transistor 41 are the same, that is, the ignition power supply and the DC power supply 30 can be shared. Note that the types and circuit configurations of the transistors 41, 42, and 43 can be changed to other types within a range that performs the same function.
[0046]
FIG. 3 shows a case where the transistor 42 (Q2, Q5) on the low side of the squib 21 is turned ON if the CPU 25 fails. That is, during the period from time t10 to t11, the CPU 25 turns on the control signals S1 and S2. Since the voltage doubler circuit does not operate, the terminal voltage of the third transistor 33 (Q3) cannot be higher than the power supply voltage VS, and the gate voltage VG of the transistor 41a (Q1) is at the level of the voltage Vt at which the transistor 41a conducts. Not reach. For this reason, the squib 21a maintains a non-energized state between the time t10 and the time t11, as indicated by the dashed ellipse. When the CPU 25 turns on the control signals S1 and S3 between time t20 and t21, the transistor 41b is not turned on even if the transistor 42b (Q5) is turned on. The gate voltage Vt at which the transistor 43 is turned on is set to a voltage higher than the power supply voltage VS, and the voltage doubler circuit does not operate normally, so that the high-side transistors 41a and 41b are not turned on. Can do. Only when the acceleration G of the impact exceeds a predetermined value and the trigger GSW22 is turned on and a voltage exceeding the voltage Vt is applied to the base of the transistor 43, the squibs 21a and 21b are energized according to the control signals S2 and S3 from the CPU 25. If it is possible to reliably determine whether or not to do so, the reliability can be improved.
[0047]
FIG. 4 shows a schematic electrical configuration of an airbag apparatus 50 according to another embodiment of the present invention. In this embodiment, parts corresponding to those in the embodiment of FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the ASIC 54 further includes an NPN bipolar transistor and a fifth resistor 57 indicated by R5 as the fourth transistor 56 indicated by Q4. If the CPU 55 turns on the collector-emitter of the transistor 56 with the control signal S3 to make it conductive, the terminal voltage of the third capacitor 33 is passed through the fifth resistor 57 and the collector-emitter of the transistor 56. Discharges and drops rapidly. For example, the terminal voltage of the third capacitor 33 can be reduced by discharging when the acceleration G of impact generated by a collision or the like in FIG. 2 does not exceed the level of G2 even if it exceeds the level of G1. In addition, when the aspect of inflating the airbag is changed according to the magnitude of the impact acceleration G detected by the G sensor 23 and the impact acceleration G is not so great, a plurality of squibs 21a as shown in FIG. , 21b, only one squib 21a is energized and ignited, and the discharge can be used when performing control so as not to inflate the airbag to the maximum extent.
[0048]
In the above embodiment, the power supply voltage VS supplied from the DC power supply 30 is boosted by the two capacitors 31 and 32, but a storage battery or the like can be used in place of the capacitors 31 and 32. Further, for example, boosting can be performed using a transformer or a coil based on the same principle as that of an ignition coil for igniting a spark plug of a vehicle engine.
[0049]
Further, the squib 21 is driven by the ASICs 24 and 54 and the CPUs 25 and 55 are separately provided. However, the ASICs 24 and 54 may include the CPUs 25 and 55. Even if the second diode 37 and the third capacitor 33 are not provided, the voltage can be boosted during the period when the trigger GSW 22 is in a conductive state, so that the squib 21 can be sufficiently ignited during this time. The diode 37 and the capacitor 33 can be omitted. The second resistor 35 may be omitted, and the second capacitor 32 may be directly connected between the positive side and the negative side of the DC power supply 30.
[0050]
Furthermore, the control signals S1 and S2 or S1 and S3 of the ignition instruction from the CPU 25 do not necessarily have to be output synchronously, and may be output under different determination conditions or output at different timings. . The transistor 43 is provided in order to further improve the reliability of airbag deployment. However, the transistor 43 may be omitted and the airbag may be deployed without the control signal S1 from the CPU 25.
[0051]
  The configuration of the embodiment described above is based on the detection results of the mechanical detection means that mechanically detects acceleration as the trigger GSW22 and the electronic detection means that electronically detects acceleration as the G sensor 23. Based on the above, in the airbag devices 20 and 50 that energize the squib 21 for deploying the airbag, the capacitors 31, 32, and 33 that are charged by power supply from the power source and the trigger GSW 22 detect an acceleration greater than a predetermined value. In this case, a transistor serving as a switching means that operates when a drive signal is supplied by discharging the capacitors 31, 32, and 33 and it is determined that there is a collision based on the detection result of the electronic detection means. 43, and when the transistor 43 serving as switching means is in an operating state, the squibTo 21It can also be thought of as energizing.
[0052]
That is, the airbag devices 20 and 50 are configured to squib 21 for deploying the airbag based on the detection results of the mechanical detection means that mechanically detects acceleration and the electronic detection means that electronically detects acceleration. Are provided with capacitors 31, 32, 33, drive signal generating means, and switching means. When the capacitor is charged by the power supply from the power source, the drive signal generation means generates the drive signal by discharging the capacitors 31, 32, 33 when the mechanical detection means detects an acceleration of a predetermined value or more. Can do. The switching means operates when a drive signal is supplied and it is determined that the vehicle is in a collision state based on the detection result of the electronic detection means, and the squib 21 is energized. Since the squib 21 is energized when the discharge of the capacitors 31, 32, 33 by mechanical detection and the electronic detection are performed simultaneously, the malfunction is prevented with a simple configuration and the determination function is improved. be able to.
[0053]
Furthermore, the airbag devices 20 and 50 are based on the detection results of the trigger GSW22 which is mechanical detection means for mechanically detecting acceleration and the G sensor 23 which is electronic detection means for electronically detecting acceleration. The squib 21 for deploying the airbag is energized, and the transistor 42, which is the first switching means that operates based on the detection result of the electronic detection means, and the capacitors 31, 32, 32, 33, and a transistor 41 that is a second switching means that is activated by a drive signal generated by discharging the capacitors 31, 32, and 33 when the mechanical detection means detects an acceleration that is greater than or equal to a predetermined value. It can also be considered that the squib 21 is energized when both the first switching means and the second switching means are in operation.
[0054]
That is, in the airbag devices 20 and 50, the squib 21 is energized when the transistors 41 and 42, which are the first switching means and the second switching means, are both in the operating state. Since the squib 21 is energized when the generation of the drive signal by the discharge of the capacitors 31, 32, 33 based on the mechanical detection and the electronic detection are performed simultaneously, the malfunction is prevented with a simple configuration. The determination function can be improved.
[0055]
Furthermore, the airbag devices 20 and 50 are based on the detection results of the trigger GSW22 which is mechanical detection means for mechanically detecting acceleration and the G sensor 23 which is electronic detection means for electronically detecting acceleration. When the squib 21 for deploying the airbag is energized and the mechanical detection means detects an acceleration greater than or equal to a predetermined value, the first drive signal is generated and the capacitor 33 is charged by the drive signal. The second drive signal is generated by discharging the capacitor 33, the first drive signal or the second drive signal is supplied, and the collision state is set based on the detection result of the electronic detection means. Transistors 41 and 42 which are switching means that operate when it is determined that there is a squib when the switching means is in an activated state. It can also be considered to perform the power supply to the 1.
[0056]
That is, the airbag devices 20 and 50 are squibs for deploying the airbag based on the detection results of the mechanical detection means that mechanically detects acceleration and the electronic detection means that electronically detects acceleration. In order to energize 21, first drive signal generation means, second drive signal generation means, and switching means are provided. The first drive signal generation means generates a first drive signal when the mechanical detection means detects an acceleration greater than or equal to a predetermined value, and charges the capacitor 33 with the first drive signal. The second drive signal generating means generates the second drive signal by discharging the capacitor 33. The switching means operates when the first drive signal or the second drive signal is supplied and when it is determined that the vehicle is in a collision state based on the detection result of the electronic detection means, to the squib 21. Is energized. Since the squib 21 is energized when the generation of the second drive signal by the discharge of the capacitor 33 based on the mechanical detection and the electronic detection are performed at the same time, the malfunction is prevented and the determination is made with a simple configuration. The function can be improved.
[0057]
Furthermore, the airbag devices 20 and 50 are based on the detection results of the trigger GSW22 which is mechanical detection means for mechanically detecting acceleration and the G sensor 23 which is electronic detection means for electronically detecting acceleration. When the squib 21 for deploying the airbag is energized, and the transistor 42, which is the first switching means that operates based on the detection result of the electronic detection means, and the mechanical detection means detect a predetermined acceleration or more In addition, the first drive signal is generated, the capacitor 33 is charged by the drive signal, and the second drive signal generated by discharging the capacitor 33 or the first drive signal is operated. A first switching means and the second switching means. There when in both operating conditions, can be considered as performing the energization of the squib 21.
[0058]
That is, the airbag devices 20 and 50 are squibs for deploying the airbag based on the detection results of the mechanical detection means that mechanically detects acceleration and the electronic detection means that electronically detects acceleration. In order to energize 21, first switching means, first drive signal generation means, second drive signal generation means, and second switching means are provided. The first switching means operates when the electronic detection means detects a predetermined acceleration or higher. The first drive signal generation unit generates a first drive signal when the mechanical detection unit detects an acceleration equal to or higher than a predetermined value, and charges the capacitor with the first drive signal. The second drive signal generating means generates the second drive signal by discharging the capacitor 33. The second switching means operates when the first drive signal or the second drive signal is supplied. When both the first switching means and the second switching means are in operation, the squib 21 is energized. Since the squib 21 is energized when the generation of the second drive signal by the discharge of the capacitor 33 based on the mechanical detection and the electronic detection are performed at the same time, the malfunction is prevented and the determination is made with a simple configuration. The function can be improved.
[0059]
【The invention's effect】
  As described above, according to the present invention, the squib isSwitching meansIn addition, only when a drive signal generated by conduction of the mechanical detection means is given, if the electronic condition is satisfied, energization for ignition is performed, so that the mechanical detection means does not conduct. Even if it is erroneously determined that the electronic condition is satisfied due to extraneous noise or the like, energization for ignition is not performed, and malfunction can be prevented. When the mechanical detection means becomes conductiveThird capacitorSince the drive signal is generated by this, reliable ignition can be performed with a simple configuration. Also,Since the third capacitor is charged by the voltage when the first and second capacitors are connected in series, the third capacitor does not derive a drive signal unless the first and second capacitors are connected in series.Therefore, it is possible to prevent malfunction and improve reliability.
[0060]
Further, according to the present invention, since the drive signal is generated by boosting, if the mechanical detection means is not conducted, the original voltage level for generating the drive signal is lowered and the possibility of malfunction is reduced. Can do.
[0061]
Further, according to the present invention, when the mechanical detection means is in the cut-off state, a DC power supply voltage is applied in parallel to the two capacitors and charged to the respective power supply voltages, and the mechanical detection means detects the impact and conducts. When in a state, the two capacitors are connected in series, and can generate a drive signal with a boosted level voltage.
[0062]
Further, according to the present invention, when the first and second capacitors are respectively charged with the DC power supply voltage and the mechanical detection means detects that the shock condition is satisfied and becomes conductive, both ends of the two capacitors are connected. Thus, the voltage at the level obtained by boosting the power supply voltage can be taken out.
[0063]
Further, according to the present invention, even when the mechanical detection means is turned on after being turned on, the third capacitor can hold a voltage at a level required as a drive signal.
[0065]
Furthermore, according to the present invention, the squib is energized when the discharge of the capacitor by the mechanical detection and the electronic detection are performed at the same time, so that the malfunction is prevented with a simple configuration and the determination function is improved. Can be planned. In addition, since the state in which the mechanical detection is performed by discharging the capacitor is maintained, the mechanical detection state can be maintained without malfunction.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic electrical configuration of an airbag apparatus 20 according to an embodiment of the present invention.
FIG. 2 is a waveform diagram showing an operation of the airbag device 20 of FIG. 1 in a normal state.
3 is a waveform diagram showing an operation of the airbag device 20 of FIG. 1 when a CPU 25 is in a failure state.
FIG. 4 is a block diagram showing a schematic electrical configuration of an airbag apparatus 50 according to another embodiment of the present invention.
FIG. 5 is a block diagram showing a schematic electrical configuration of a conventional airbag apparatus.
[Explanation of symbols]
20, 50 Airbag device
21, 21a, 21b squib
22 Trigger GSW
23 G sensor
24, 54 ASIC
25,55 CPU
30 DC power supply
31, 32, 33 capacitors
34, 35, 44, 45, 57 Resistance
36, 37 diode
41, 41a, 41b, 42, 42a, 42b, 43, 56 transistors

Claims (4)

The airbag is deployed based on the detection results of the mechanical detection means that mechanically conducts the contact when the acceleration exceeds a predetermined level and the electronic detection means that outputs an electrical signal corresponding to the applied acceleration. In the airbag device that energizes the squib for
First and second capacitors charged by power from a power source;
When an acceleration of a predetermined level or more is applied, the mechanical detection means causes the first capacitor and the second capacitor, which are connected in parallel, to conduct in contact with each other, thereby connecting the first capacitor to the first capacitor. A third capacitor charged by a voltage when the capacitor and the second capacitor are connected in series;
The drive signal supplied from the third capacitor is supplied until the charge charged in the third capacitor is discharged and the voltage of the third capacitor drops below a predetermined value, and Switching means that operates when it is determined that there is a collision based on the detection result of the electronic detection means,
An airbag apparatus characterized in that energization of the squib is performed when the switching means is in an operating state. The airbag is deployed based on the detection results of the mechanical detection means that mechanically conducts the contact when the acceleration exceeds a predetermined level and the electronic detection means that outputs an electrical signal corresponding to the applied acceleration. In an airbag apparatus that energizes a plurality of squibs for causing
First and second capacitors charged by power from a power source;
When an acceleration of a predetermined level or more is applied, the mechanical detection means causes the first capacitor and the second capacitor, which are connected in parallel, to conduct in contact with each other, thereby connecting the first capacitor to the first capacitor. A third capacitor charged by a voltage when the capacitor and the second capacitor are connected in series;
The drive signal supplied from the third capacitor is supplied until the charge charged in the third capacitor is discharged and the voltage of the third capacitor drops below a predetermined value, and First switching means that operates when it is determined that the vehicle is in a collision state based on a detection result of the electronic detection means;
A second switching means provided for each of the squibs in order to control energization for each of the plurality of squibs,
When the first switching means is in an operating state and the second switching means is in an operating state, the squib corresponding to the second switching means in the operating state is energized. An airbag device. The first capacitor has one terminal connected to one side of the DC power supply voltage via a diode that is in the forward direction during charging, and the other terminal connected to the other side of the DC power supply voltage. It is connected via a,
The second capacitor has one terminal connected to one side of the DC power supply voltage via a second resistor, the other terminal connected to the other side of the DC power supply voltage ,
The mechanical detection means conducts the connection between the first capacitor and the first resistor and the connection between the second capacitor and the second resistor in the conductive state. Item 3. The airbag device according to Item 1 or 2 . A connection portion between the before and Symbol diode first capacitor, between the input portion of the drive signal of the switching means driving signal from the third capacitor is supplied, as a forward direction when the discharge The airbag device according to claim 3 , further comprising a second diode connected thereto.

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