Trigger device for triggering a passive restraint device in a car

• US 5,463,260 A
• Filed: 10/20/1993
• Issued: 10/31/1995
• Est. Priority Date: 01/20/1993
• Status: Expired due to Fees

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Ono, Katsuyasu
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US08/139,104
• Time in Patent Office: 741 Days
• Field of Search: 200/61.45 R, 200/61.53, 200/61.45 M, 335/205, 335/206, 335/207, 307/116-121, 280/731-735, 180/282
• US Class Current: 307/121
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002
• CPC Class Codes: H01H 35/147 the switch being of the reed switch type

Abstract

A trigger device which, when it is used in a seat belt tightening device or in an air bag device, prevents the malfunction to enhance reliability and also which is simple in structure, is easy to assemble and is inexpensive. The trigger device includes an ignition circuit which, when an opening/closing switch 24 is closed, allows the electricity of a power supply 23 to flow to ignite a gas generator 8, a movable magnet 22 which, when a car is suddenly decelerated, can be inertially moved to a first position to close the opening/closing switch 24 to electrically energize the ignition circuit, and a fixed magnet 21 fixed to a frame 20 of a non-magnetic member so as to be able to hold the movable magnet 22 at a second position, in which the opening/closing switch 24 is opened, by a repelling magnetic force acting between the movable and fixed magnets. And, when a predetermined or greater acceleration is applied to the movable magnet 22, then the movable magnet 22 is moved to the direction of the first position against the repelling magnetic force acting between the fixed and movable magnets so as to be able to electrically energize the ignition circuit.

Claims

1. A trigger device operable in response to an acceleration exceeding a predetermined value to ignite a gas generator in a vehicle, the trigger device comprising:

a power supply;

an electric ignition device coupled to the gas generator;

switch means connected between the electric ignition device and the power supply to selectively energize the electric ignition device;

a moveable magnet moveable between a first position, wherein the switch means is operated to energize the electric ignition device, and a second position wherein the switch means is not operated; and

a fixed magnet fixedly mounted to a frame of the vehicle to bias the moveable magnet toward the second position by a magnetic force acting between a first magnetic pole of the movable magnet and a second magnet pole of the fixed magnet, the first magnetic pole of the movable magnet adjoining the second magnetic pole of the fixed magnet;

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the magnetic force when acceleration is applied to the movable magnet continuously for at least a predetermined period of time.

2. The trigger device of claim 1, wherein the movable magnet is disposed with respect to the fixed magnet so that the first magnetic pole of the movable magnet opposes the second magnetic pole of the fixed magnet, which has the same polarity as the first magnetic pole, the movable magnet being energized to the second position by a repulsive magnetic force acting between the movable magnet and the fixed magnet, and

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the repulsive magnetic force to operate the switch means if an inertial force acting on the movable magnet is greater than the repulsive magnetic force acting between the movable magnet and the fixed magnet.

3. The trigger device of claim 2, wherein the movable magnet and the fixed magnet are respectively disposed so as to mutually face to each other with the switch means disposed between the movable magnet and the fixed magnet.

4. The trigger device of claim 2, wherein the fixed magnet is formed in a ring shape, and the switch means is disposed in an internal space existing on an opening end side of the fixed magnet.

5. The trigger device of claim 1, wherein the movable magnet is disposed proximate the fixed magnet so that the first magnetic pole of the movable magnet opposes the second magnetic pole of the fixed magnet, which has the different polarity from the first magnetic pole, the movable magnet being held at the second position by an attracting magnetic force acting between the movable magnet and the fixed magnet, and

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the attracting magnetic force to operate the switch means if an inertial force acting on the movable magnet is greater than the attracting magnetic force acting between the movable magnet and the fixed magnet.

6. The trigger device of claim 1, wherein the movable magnet includes a pair of needle-shaped electrodes on a surface which opposes the fixed magnet, said electrodes being electrically connected to each other, the switch means comprises a conducting wire and in which the needle-shaped electrodes contact the conducting wire and provide a short-circuit between open ends of the conducting wire for energizing the electric ignition device wherein the moveable magnet is in the first position.

7. A trigger device operable in response to an acceleration exceeding a predetermined value to ignite a gas generator in a vehicle, the trigger device comprising:

an electric ignition device coupled to the gas generator;

a coil disposed in a recess formed in a frame of the vehicle, and the coil being electrically connected to the electric ignition device;

a moveable magnet disposed movably within the coil for generating an induced electromotive current in accordance with a movement of the moveable magnet, the movable magnet being moveable between a first position and a second position; and

a fixed magnet fixed to the frame of the vehicle, the fixed magnet being disposed proximate the movable magnet so that a first magnetic pole of the movable magnet opposes a second magnetic pole of the fixed magnet, which has the same polarity as the first magnetic pole, the movable magnet being energized to the second position by a repulsive magnetic force acting between the movable magnet and the fixed magnet;

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the repulsive magnetic force to energize the electric ignition device by the electromotive current if an inertial force acting on the movable magnet is greater than the repulsive magnetic force acting between the movable magnet and the fixed magnet the acceleration is applied continuously for at least the predetermined period of time.

8. A trigger device operable in response to an acceleration exceeding a predetermined value to ignite a gas generator, for use in a seat belt tightening device which is driven by a gas pressure to rotate a winding shaft of a retractor in a seat belt retracting direction in a vehicle collision, the trigger device comprising:

a power supply;

an ignition heater coupled to the gas generator;

an opening/closing switch connected between the ignition heater and the power supply to selectively energize the ignition heater;

a movable magnet moveable between a first position, wherein the opening/closing switch is closed to energize the ignition heater, and a second position wherein the opening/closing switch is open; and

a fixed magnet fixedly mounted to a frame of the vehicle proximate the moveable magnet to hold the movable magnet at the second position by a magnetic force acting between the movable magnet and the fixed magnet;

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the magnetic force when acceleration is applied to the movable magnet continuously for at least a predetermined period of time.

9. The trigger device of claim 8, wherein the movable magnet is disposed so that a first magnetic pole of the movable magnet opposes a second magnetic pole of the fixed magnet, which has the same polarity as the first magnetic pole, the movable magnet being biased to the second position by a repulsive magnetic force acting between the movable magnet and the fixed magnet;

and

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved towards the first position against the repulsive magnetic force to operate the opening/closing switch if an inertial force acting on the movable magnet is greater than the repulsive magnetic force acting between the movable magnet.

10. The trigger device of claim 9, wherein the movable magnet and the fixed magnet are respectively disposed to mutually oppose each other with the opening/closing switch between the movable magnet and the fixed magnet.

11. The trigger device of claim 8, wherein the movable magnet is disposed so that a first magnetic pole of the movable magnet adjoins a second magnetic pole of the fixed magnet, which has the different polarity from the first magnetic pole, the movable magnet being held at the second position by an attracting magnetic force acting between the movable magnet and the fixed magnet;

and

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the attracting magnetic force to operate the opening/closing switch if an inertial force acting on the movable magnet is greater than the attracting magnetic force acting between the movable magnet and the fixed magnet.

12. The trigger device of claim 9, wherein the fixed magnet is formed in a ring shape, and the opening/closing switch is disposed in an internal space existing on an opening end side of the fixed magnet.

13. A trigger device operable in response to an acceleration exceeding a predetermined value to ignite a gas generator, the trigger device comprising:

a power supply;

an electric ignition device coupled to the gas generator;

an inverter disposed in an ignition circuit of the electronic ignition device to output a signal when an input signal is absent;

a moveable magnet having a non-conductive blade, thereon for energizing the electric ignition device by cutting a conducting wire provided in the ignition circuit;

said movable magnet being moveable between a first position to cut the conducting wire with the non-conductive blade so as to energize the electric ignition device and a second position remote from the conducting wire so as not to energize the electric ignition device, the nonconductive blade being disposed on a surface of the movable magnet; and

a fixed magnet being fixedly mounted to a frame of the vehicle in opposition to the surface of the moveable magnet to hold the movable magnet at the second position by a magnetic force acting between the movable magnet and the fixed magnet;

wherein the movable magnet is disposed proximate the fixed magnet so that the movable magnet is inertially moved toward the first position against the magnetic force when the acceleration is applied to the movable magnet continuously for at least a predetermined period of time.