Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
  • B60R21/013—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over
  • B60R21/0132—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over responsive to vehicle motion parameters, e.g. to vehicle longitudinal or transversal deceleration or speed value
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
  • B60R21/017—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including arrangements for providing electric power to safety arrangements or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves

Definitions

• the invention is based on an electronic device according to the preamble of claim 1 or an operating method according to the preamble of claim 7.
• a safety device for vehicle occupants is described, for example, in the magazine 1141 Ingenieurs de 1'Automobile (1982) No. 6, page 69 ff, in particular FIG. 19 on page 74.
• Safety device comprises so-called squibs, which are controlled by a control unit. After activation, the squibs activate a gas-generating propellant charge, which is operatively connected to a restraint for
• Reference voltage source supplied voltage compared.
• the accuracy of such a measurement depends on the accuracy of the test current which is applied to the squib during the test. With integrated circuits however, it is comparatively difficult and expensive to provide a high-precision power source.
• the device according to the invention with the features of claim 1 and the operating method for this device with the features of claim 7 offer in particular the advantage of a high overload safety of the final stage of the control device which controls the squib, even if the resistance value of the squib deviates greatly from its setpoint, in particular is significantly below this.
• a comparatively small-sized output stage can be used, which requires only a small chip area when implemented in integrated technology. This in turn leads to a cost reduction.
• the fact that a squib is triggered in cycles with a resistance value that deviates from its nominal value, with a current measurement being carried out with each cycle, allows a very flexible reaction to changes in the squib resistance.
• the minimum energy required to activate the squib can be provided even if the resistance value of the squib deviates very greatly from its target value.
• the cyclical actuation of the squib limits the maximum energy required of the control unit even in the event of a short circuit in the squib resistance. Furthermore, as a result of a sharp increase in the current amplitude and the resulting short-circuit and / or shunt firing, reliable activation of the squib can be achieved even under very difficult operating conditions.
• FIG. 1 shows a block diagram of an electronic device
• FIG. 2 shows a somewhat more detailed block diagram of the electronic device with illustration of the squib
• FIG. 3, FIG. 4, FIG. 5 and FIG. 6 show current flow diagrams as a function of time
• FIG. 7 shows a flow diagram
• FIG 8 shows a further exemplary embodiment of the electronic device with a plurality of output stages for the control of a plurality of squibs.
• FIG. 1 shows a simplified block diagram of an electronic device 1 of the generic type.
• This device comprises a sensor 2 which records acceleration values of the vehicle and whose output connection is connected to the
• control unit 3 Input connection of a control unit 3 is connected, which evaluates the output signals of the sensor 2.
• the control unit 3 is in turn connected to restraint means 4a, 4b for protecting the vehicle occupants, such as in particular the airbag, belt tensioner and / or the like. If a critical accident situation occurs, the control unit 3 controls the restraint means 4a, 4b, which then offer protection to the occupants.
• FIG. 2 shows a detailed block diagram of an electronic device of the generic type, in which the squib 5 itself is shown.
• the device 1 in turn comprises a sensor 2, which is connected to a control unit 3. Output connections of the control device 3 are connected to switching means S1, S2, which are connected in series to a squib 5. So that is further connected in series Resistor RM, which is connected to ground. At least one restraint 4a is operatively connected to the squib 5. This operative connection is indicated by the connection shown in dashed lines in FIG. 2 between the squib 5 and the retaining means 4a.
• the device 1 further comprises a comparator 7 in the form of an operational amplifier, the non-inverting input connection of which is connected to the ground connection of the resistor RM.
• the inverting input connection of the comparator 7 is one, preferably several
• Voltage values switchable reference voltage source connected is formed by a voltage divider (resistors R200, R201, R202, R203) connected to the operating voltage.
• a third switching element S3 enables the alternating series connection of the resistors R201, R202, R203 to the high-lying resistor R200, so that the center tap of the voltage divider connected to the inverting input terminal of the comparator 7 differs
• the switching element S3 can be controlled by the control unit 3.
• the output terminal of the comparator 7 is connected to an input terminal of the control device 3.
• Sensor 2 delivers output signals corresponding to vehicle acceleration, which are evaluated by control unit 3.
• the output signal of the sensor 2 is usually integrated and the integration value is compared with a predefinable threshold value. If this threshold value is exceeded, which indicates a serious accident, the switching elements S1, S2 are controlled by the control unit 3. The consequence of this is that a current is applied to the at least one squib 5 and is thereby heated.
• the squib 5 is operatively connected to a retaining means 4a, such as in particular an airbag, and in turn activates a gas-generating propellant charge that inflates the airbag.
• a resistor RM is also connected in series with the aforementioned components, through which the ignition current also flows, with which the squib 5 is acted upon. A voltage then drops across this resistor RM, which by means of the comparator 7 is comparable to at least one reference voltage.
• this ignition current is now measured when the squib 5 is actuated with an ignition current, and preferably after time intervals which can be predetermined in each case and which are defined, for example, by a clock generator 8.
• This clock generator 8 is preferably integrated in the control unit 3.
• FIG. 2 it can also be a separate assembly.
• the manner in which the current acting on the squib 5 is measured and controlled is explained below with reference to the diagrams shown in FIGS. 3 to 7.
• Current curves are plotted as a function of time in the diagrams in FIGS. 3 to 6, while the diagram in FIG. 7 represents a flow diagram.
• the at least one squib 5 (FIG. 2) is activated in the starting step 100 and current is applied in accordance with step 101.
• step 104 the current I flowing through the squib 5 is measured by the
• step 107 the current I is compared to a first setpoint II of the current. This comparison is carried out in such a way that the comparator 7 compares the voltage drop detected at the resistor RM with a first voltage reference value. As long as the current I remains below the first current limit value II, the squib 5, as can be seen from step 103 of the diagram in FIG. 7, is supplied with a current, the duty cycle of which is TV 1. In a preferred embodiment of the invention the first current limit value II is ⁇ 3 amperes.
• the duty cycle is therefore TV 1, as can be seen from the illustration in the diagram in FIG. 3.
• the ignition current flows through the squib 5 as a continuous current until it is finally activated.
• the current I flowing through the squib 5 exceeds the first current limit value II, it is checked in step 108 of FIG. 7 whether the current I flowing through the squib 5 is still below a second current limit value 12, which in a preferred exemplary embodiment of the invention is, for example is about 6 amps. If this is the case, the pulse duty factor TV of the current control is changed in accordance with step 102 of FIG.
• the current control described above results in a lower load on the output stage which acts on the squib 5.
• a small-sized output stage can be used in an advantageous manner, which only requires a comparatively small chip area when implemented in integrated technology.
• a reduction in overall size can be achieved without uncontrollable thermal problems.
• the fact that a pulsed control of the squib is provided and that a measurement process for the current I is carried out at least every cycle, can react very quickly to a change in the current I and, if necessary, the clock ratio TV can be adapted immediately.
• a clock generator 8 is used which emits a clock frequency of a few 10 kilohertz, in particular 40 kilohertz.
• the duty cycle TV is expediently represented as a quotient with the denominator 2 or a multiple thereof, for example 1.1 / 2, 1/8, 1/16.
• the fact that the squib 5 can also be actuated with relatively high current intensities I can further ensure that the actuation process can be eliminated by disturbing conditions, such as short circuits or shunts, by burning free. As a result, the squib 5 can still be activated as planned, even in unfavorable situations. In this way, it is possible to control a squib 5 even when its actual resistance deviates very greatly from its target resistance.
• the resistances of commercially available squibs are of the order of a few ohms, in particular around 2 ohms.
• the electronic device 1 particularly advantageously comprises an integrated electronic circuit 80 (FIG. 8), in which a plurality of switching elements 81a, 81b, 81c, 81d of driver circuits 82a, 82b, 82c, 82d for these switching elements and of comparators 83a, 83b, 83c , 83d are integrated.
• a plurality of squibs 5 can thus be controlled, the high level of integration can nevertheless ensure a small and space-saving design.
• the connecting lines IGHO, IGH1, IGH2, IGH3 connected to the switching elements 81a, 81b, 81c, 81d lead to those not shown here
• Primers which are arranged outside of this electronic circuit 80, in the immediate vicinity of the restraining means.
• Resistors R50, R51, R52, R53 are drawn in series with the switching elements 81a, 81b, 81c, 81d, and the current through which the squibs are applied flows through them.
• the connecting lines of the aforementioned resistors R50, R51, R52, R53 are each connected to input connections of comparators 83a, 83b, 83c, 83d, which sense the voltage drop occurring at the respective resistor and compare it with a predetermined reference value.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Air Bags (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 1995
  • 1995-08-30 DE DE19531899A patent/DE19531899B4/de not_active Expired - Fee Related
• 1996
  • 1996-08-07 EP EP96928342A patent/EP0844950A1/de not_active Withdrawn
  • 1996-08-07 KR KR1019980701440A patent/KR19990044204A/ko not_active Application Discontinuation
  • 1996-08-07 JP JP50967997A patent/JP3759619B2/ja not_active Expired - Fee Related
  • 1996-08-07 US US09/029,411 patent/US6068287A/en not_active Expired - Fee Related
  • 1996-08-07 WO PCT/DE1996/001472 patent/WO1997008022A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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