Circuit arrangement for driving an occupant protection system gas generator whose ignition process can be influenced by a magnetic field

• US 6,564,717 B2
• Filed: 12/14/2001
• Issued: 05/20/2003
• Est. Priority Date: 12/15/2000
• Status: Expired due to Fees

• Current Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Original Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Inventors: Roth, Gerhard, Wetzel, Guido, Florian, Johann, Haerle, Thomas
• Primary Examiner(s): Gregory, Bernarr E.
• Assistant Examiner(s): BLACKNER, HENRY A
• Application Number:
  US10/017,496
• Publication Number:
  US 20020073868A1
• Time in Patent Office: 522 Days
• Field of Search: 280/736, 280/737, 280/742, 102/206, 102/215, 102/218, 102/262
• US Class Current: 102/262
• CPC Class Codes: B60R 2021/2636 The volume of gas being continuously adjustable
• CPC Class Codes: B60R 21/017 including arrangements for providing electric power to safety arrangements or their actuating means, e.g. to pyrotechnic fuses or electro-mechanic valves
• CPC Class Codes: B60R 21/264 using instantaneous generation of gas, e.g. pyrotechnic B60R21/268 takes precedence

Abstract

The disclosure describes a circuit arrangement for driving an occupant protection system gas generator whose ignition process can be influenced by a magnetic field; this is based on a switching control principle, with the load coil generating the magnetic field being itself used as a component part of the switching control. For a fast reduction of the magnetic field and thus for accelerating the ignition process, a resistor may by connected into the free-wheeling branch, which is bridged in normal operation. Alternatively, it is possible to effect a return feed of the energy stored in the coil into the self-sufficiency capacitor.

Claims

1. Circuit arrangement (1) for driving an occupant protection system (3) gas generator (2) whose ignition process can be influenced by a magnetic field, comprising:

a) a coil (4) for generating an electromagnetic field,

b) a supply voltage source (U) and a parallel self-sufficient capacitor (15), which will supply the gas generator (2) for a period of self-sufficiency in the event of a failure of the supply voltage source (U),

c) a control circuit (12), which controls a circuit element (11) connected in series to the coil (4) by pulse width modulation,

d) and a free-wheeling diode (10), which is connected in between circuit element (11) and coil (4), in parallel to the coil (4) and with a polarity opposite to the polarity of the supply voltage source (U).

2. Circuit arrangement according to claim 1 wherein a load resistor (16) is arranged in series to a free-wheeling current path, and with the load resistor (16) having a switchable bridging (13).

3. Circuit arrangement according to claim 2 wherein, for building up as well as for controlling the constancy of the magnetic field in the coil (4), the load resistor (16) is bridged, and wherein for a faster reduction of the magnetic field in the coil (4), in particular for accelerating the ignition process of the vehicle occupant protection device, the bridging is opened, and wherein the coil is discharged via the load resistor (16).

4. Circuit arrangement according to claim 1 wherein

a) a first circuit element (11a) is connected between supply voltage source (U) and the coil (4), and a second circuit element (11b) is connected between the coil (4) and the ground,

b) the free-wheeling diode (10) is connected in between the first circuit element (11a) and the coil (4), in parallel to the coil (4) and with a polarity opposite to the polarity of the supply voltage source (U), and

c) a further diode (17), with a polarity opposite to the polarity of the supply voltage source (U), is also provided and connects the coil (4) orientated towards the second circuit element (11b) with the parellel self-sufficient capacitor (15), and

d) the control circuit (12) drives by pulse width modulation at least the first circuit element (11a) in order to charge the coil (4).

5. Circuit arrangement according to claim 4 wherein the discharge of the coil (4) is effected by a return feed of the energy stored therein into the parallel self-sufficient capacitor (15);

to this end both circuit elements (11a, 11b) are opened.

6. Circuit arrangement according to claim 1, wherein:

a) a measurement element (5) is provided for the detection of a current (i) flowing through the coil (4);

b) the control circuit (12) will compare the current (i) through the coil (4) with a nominal value, and drive the circuit element(s) (11, 11a, 11b) by pulse width modulation in relation to the result of the aforesaid comparison, and thus regulates the current (i) to assume the nominal value.