Electrical release circuit for a passenger protection system

• US 20030189325A1
• Filed: 05/27/2003
• Published: 10/09/2003
• Est. Priority Date: 06/08/2000
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Swart, Marten
• Granted Patent: US 7,048,302 B2
• Time in Patent Office: Days
• US Class Current: 280/735
• CPC Class Codes: B60R 2021/01027 Safing sensors
• 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

Abstract

The invention relates to a passenger protection system which is provided with a safing switch (20). If only one ignition stage (2) of a passenger protection airbag which can be ignited in two stages is ignited by a control device (6), the safing switch being closed, a circuit module (16) output (46) that is parallel to the safing switch is switched to a signal mode corresponding to the closed safing switch. In this way, the second ignition stage (4) can then be ignited by the control device (6) even when the safing switch is no longer closed.

Claims

1. A method for releasing the firing capability of at least two firing stages (2;

4) which can be fired separately in a vehicle occupant protection system, in which method a safing signal which is used to release the firing capability of the firing stages (2;

4) is prolonged if only one firing stage is fired in order to protect the vehicle occupant when there is an accident.

2. An electric release circuit for a vehicle occupant protection system having at least two firing stages, containing a safing switch (20), at least one accident sensor (8) and a controller (6) which, as a function of the output signal of the accident sensor, generates control signals for firing only one firing stage (2, 4) or both firing stages (2, 4) simultaneously or with a delay, the safing switch (20) responding to a physical parameter and closing when a threshold value at which it is not yet necessary to provide vehicle occupant protection by means of the protection system is exceeded, and the firing stages (2, 4) being connected in such a way that they can be fired only when a signal which corresponds to the closed safing switch is present at a safing signal output (39) and a firing signal which is assigned to them is present, characterized in that a switching device (14, 16) which is connected to the safing signal output (39) and to the controller (6) is provided which brings about a signal state corresponding to the closed safing switch when the safing switch (20) is closed and when there is a controller (6) and when a controller (6) which brings about the firing of only one firing stage is present at the safing signal output.

3. The circuit as claimed in claim 2, characterized in that the switching device (14, 16) has a circuit component (16) with a control input (40), a signal input (19) and an output (46), the control input (40) being connected to the safing signal output (39), the signal input (19) being connected to the controller (6), the output (46) being located in parallel with the safing switch (20) and the output (40) assuming a signal stage which corresponds to the closed safing switch after a safing signal which appears at the safing signal output (39) when the safing switch closes is applied to the control input (40) and a clock signal which is generated by the controller (6) when it is necessary to fire only one firing stage is applied to the clock input (19).

4. The circuit as claimed in claim 3, characterized in that a timing element (36) which is triggered by closing the safing switch (20) is connected downstream of the safing switch (20), in that an output of the timing element is connected to an input of an OR element (38) whose other input is connected to the safing switch (20) and whose output forms the safing signal output (39).

5. The circuit as claimed in claim 4, characterized in that the safing switching (20) is contained in a branch of a bridge circuit (22), and in that a comparator (32) is provided, the one input of which comparator (32) is connected to the safing switch (32) and to the output (46) of the circuit module (16), and the other input of which comparator (32) is connected to the other branch of the bridge circuit, and the output of which circuit module (16) is connected to the input of the timing element (36) and to the one input of the OR element (38).

6. The circuit as claimed in one of claims 2 to 5, characterized in that the switching device (14, 16) has a reset input (15).

7. The circuit as claimed in claim 6, characterized in that the reset input is connected to the output of a NAND element (14) whose inputs are connected to resetting outputs (10, 12) of the controller (6).

8. The circuit as claimed in claim 3 and 5, characterized in that a diode (48) is provided between the output of the circuit module (16) and the bridge circuit (20).

9. The circuit as claimed in claim 3, characterized in that the circuit module (16) is formed by a D-flipflop.