Dual resistance switch for buckle confirmation

• US 5,590,904 A
• Filed: 08/15/1995
• Issued: 01/07/1997
• Est. Priority Date: 08/15/1995
• Status: Expired due to Term

• Current Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Vehicle Safety Systems Incorporated (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Nill, Robert E., Niedzwiecki, Leon P., Ellis, Robert P.
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): English, Peter C.
• Application Number:
  US08/515,131
• Time in Patent Office: 511 Days
• Field of Search: 180/268, 180/269, 180/270, 280/735, 280/734, 280/728.1, 280/806, 280/801.1, 200/61.58 B, 340/457.1, 340/438
• US Class Current: 280/735
• CPC Class Codes: B60R 2022/4816 for sensing locking of buckle
• CPC Class Codes: B60R 21/01546 using belt buckle sensors
• CPC Class Codes: B60R 22/48 Control systems, alarms, or interlock systems, for the correct application of the belt or harness

Abstract

A vehicle occupant restraint system (20) includes an inflatable air bag (41) and an actuatable inflator (40) for, upon actuation, providing inflation fluid for inflating the air bag. A seat belt (105) extends across the vehicle occupant to restrain the occupant. A tongue (110) is connected with the seat belt (105), and a buckle (57) receives and latches the tongue (110) in the buckle (57). A pretensioner (44) is operatively connected to the belt (105). An indicator (59) indicates to the occupant if the tongue (110) is not received in the buckle (57). A seat belt buckle switch (66) is operatively connected to the buckle (57). The seat belt buckle switch (66) has electrically conductive normally closed contacts (74, 76) which open upon insertion of the tongue (110) into the buckle (57). A resistor network is electrically connected to the normally closed contacts (74, 76). The resistor network provides a first electrical signal having a first characteristic when the normally closed contacts (74, 76) are closed and a second electrical signal having a second characteristic when the normally closed contacts (74, 76) are open. A controller (24) is operatively connected to the inflator (40), the pretensioner (44), the resistor network (60, 72) and the indicator (59). The controller (24) controls actuation of the inflator (40), the pretensioner (44) and the indicator (59) in accordance with the first and second electrical signals.

Claims

1. An apparatus for restraining a vehicle occupant, said apparatus comprising:

a seat belt for extending across the vehicle occupant;

a tongue associated with said seat belt;

a buckle for receiving and latching said tongue in said buckle;

a seat belt buckle switch operatively connected to said buckle, said seat belt buckle switch having electrically conductive normally closed contacts;

a resistor network electrically connected to said normally closed contacts, said resistor network comprising a first resistor in series with said contacts and a second resistor in parallel with said contacts, said resistor network providing a first electrical signal having a first characteristic dependent upon the resistance value of said first resistor when said seat belt buckle switch is closed and a second electrical signal having a second characteristic dependent upon the resistance values of said first resistor and said second resistor when said seat belt buckle switch is open; and

a controller operatively connected to said resistor network for monitoring said first and second signals.

2. The apparatus of claim 1 wherein said apparatus further includes a pretensioner operatively connected to said seat belt.

3. The apparatus of claim 1 further including indicator means for indicating if the tongue is received in said buckle.

4. The apparatus of claim 1 wherein the resistance value of said first resistor is about 100 ohms.

5. The apparatus of claim 1 wherein the resistance value of said second resistor is about 300 ohms.

6. The apparatus of claim 1 wherein said apparatus further comprises an inflatable air bag, and an actuatable inflator for providing a source of inflation fluid for inflating said air bag, said inflator is operatively connected to said controller, said controller controls actuation of said inflator.

7. The apparatus of claim 1 further including a memory for storing a value indicative of whether said tongue is received in said buckle, said memory being connected to said controller, said controller accesses the value.

8. A vehicle occupant restraint apparatus comprising:

an inflatable air bag;

an actuatable inflator for, upon actuation, providing inflation fluid for inflating said air bag;

a seat belt for extending across the vehicle occupant;

a tongue connected with said seat belt;

a buckle for receiving and latching said tongue in the buckle;

a pretensioner operatively connected to said seat belt;

an indicator for indicating if the tongue is received in said buckle;

a seat belt buckle switch operatively connected to said buckle, said seat belt buckle switch having electrically conductive normally closed contacts which open upon insertion of said tongue into said buckle;

a resistor network electrically connected to said normally closed contacts, said resistor network providing a first electrical signal having a first characteristic when said normally closed contacts are closed and a second electrical signal having a second characteristic when said normally closed contacts are open; and

a controller operatively connected to said resistor network, said inflator, said pretensioner, and said indicator, said controller controlling actuation of said inflator, said pretensioner, and said indicator in accordance with said first and second electrical signals;

said resistor network comprising a first resistor in series with said contacts and a second resistor in parallel with said contacts, said resistor network providing the first electrical signal, when said normally closed contacts are closed, the first characteristic of the first electrical signal being dependent upon the resistance value of said first resistor, said resistor network providing the second electrical signal, when said normally closed contacts are open, the second characteristic of the second electrical signal being dependent upon the resistance values of said first resistor and said second resistor.