Inertia switch

• US 4,902,861 A
• Filed: 03/20/1989
• Issued: 02/20/1990
• Est. Priority Date: 03/20/1989
• Status: Expired due to Fees

• Current Assignee: Siemens-Bendix Automotive Electronics LP
• Original Assignee: Siemens-Bendix Automotive Electronics LP
• Inventors: Cook, John E.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US07/326,825
• Time in Patent Office: 337 Days
• Field of Search: 200/61.25, 200/61.45 R, 200/61.53, 200/83 N
• US Class Current: 200/61.48
• CPC Class Codes: H01H 35/142 Damping means to avoid unwanted response

Abstract

An inertia switch for a supplemental inflatable restraint system. The switch comprises a casing that is divided into two chambers by an axially movable diaphragm. The diaphragm carries an electrical contact on one face and an inertial mass on the other. A pair of terminals are disposed in the path of travel of the electrical contact so that when the switch is subjected to axial deceleration force the contact is urged toward the terminals. Actual contact is made when the deceleration force equals or exceeds a predetermined deceleration characteristic. The deceleration characteristic is a function not only of the diaphragm, the electrical contact, and the mass, but also of a control orifice located in an orifice that communicates the two chambers with each other. The chambers are constructed such that air is forced from one chamber into another through the control orifice when deceleration occurs and this imparts a dampening to the motion of the diaphragm.

Claims

1. An inertia switch comprising:

a casing that is divided into two chambers by an axially movable diaphragm;

an electrical contact carried by said diaphragm on a face thereof that bounds one of said chambers, said electrical contact being disposed centrally on said face;

a pair of spaced apart terminals disposed in said one chamber in the path of said electrical contact as said diaphragm moves toward said one chamber, a circuit being completed between said pair of terminals when said pair of terminals is contacted by said electrical contact;

orifice means passing through said electrical contact and said diaphragm to communicate said two chambers with each other, said orifice means comprising a control orifice, said control orifice being in said electrical contact;

said inertia switch occupying an off state, when subjected to axial force below a predetermined magnitude and duration characteristic in a sense urging said electrical contact and said diaphragm toward said pair of terminals, said off state being defined by said electrical contact being spaced from said pair of terminals; and

said inertia switch assuming an on state, when subjected to axial force in said sense equaling or exceeding said predetermined magnitude and duration characteristic, said on state being defined by said electrical contact being placed in contact with said pair of terminals;

said orifice means functioning to conduct a gas from said one chamber to the other of said chambers in response to displacement of said electrical contact and said diaphragm toward said pair of terminals, said control orifice restricting the flow of gas through said orifice means to impart dampening to the motion of said diaphragm and said electrical contact toward said pair of terminals.

2. An inertia switch as set forth in claim 1 in which said diaphragm is constructed so as to be inherently biased in the axial direction away from said pair of terminals.

3. An inertia switch as set forth in claim 2 in which said diaphragm includes a mass that is carried centrally by said diaphragm on the face thereof that is toward said other chamber, said orifice means also passing through said mass.

4. An inertia switch comprising:

a casing that is divided into two chambers by an axially movable diaphragm;

an electrical contact carried by said diaphragm on a face thereof that bounds one of said chambers, said electrical contact being disposed centrally on said face;

a pair of spaced apart terminals disposed in said one chamber in the path of said electrical contact as said diaphragm moves toward said one chamber, a circuit being completed between said pair of terminals when said pair of terminals is contacted by said electrical contact;

orifice means passing through said electrical contact and said diaphragm to communicate said two chambers with each other, said orifice means comprising a control orifice;

said inertia switch occupying an off state, when subjected to axial force below a predetermined magnitude and duration characteristic in a sense urging said electrical contact and said diaphragm toward said pair of terminals, said off state being defined by said electrical contact being spaced from said pair of terminals; and

said inertia switch assuming an on state, when subjected to axial force in said sense equaling or exceeding said predetermined magnitude and duration characteristic, said on state being defined by said electrical contact being placed in contact with said pair of terminals;

in which said diaphragm is constructed and arranged so as to be inherently biased in the axial direction away from said pair of terminals;

in which said diaphragm includes a mass that is carried central by said diaphragm on the face thereof that is toward the other of said chambers, said orifice means also passing through said mass; and

including a stop for engaging said mass to set a limit for the extent to which said diaphragm is biased away from said pair of terminals.

5. An inertia switch as set forth in claim 4 in which said stop is adjustable on said casing.

6. In an inertia switch, the combination of a casing having a diaphragm portion dividing the casing into two chambers, orifice means passing through said diaphragm portion for communicating said two chambers with each other, said two chambers being constructed and arranged such that in response to an axial force of predetermined magnitude and duration applied to said switch, said diaphragm portion is urged axially toward a terminal means in one of said chambers so that an electrical contact portion of said diaphragm portion can make contact therewith and thereby cause the switch to give a switch signal via said terminal means, said orifice means comprising a control orifice through which air is forced from said one chamber to the other to impart dampening to the motion of said diaphragm portion as said diaphragm portion and electrical contact portion are displaced toward said terminal means.

7. The combination set forth in claim 6 wherein said control orifice is in said electrical contact portion.

8. Inertia switch structure comprising:

a casing;

a diaphragm that divides said casing into two chambers and is axially displaceable within said casing;

orifice means in said structure through which a gas in one of said two chambers can be driven from said one chamber;

electrical terminal means disposed in said one chamber in the path of axial displacement of said diaphragm;

said two chambers, said diaphragm, and said terminal means being constructed and arranged such that in response to an axial force of predetermined magnitude and duration applied to said inertia switch structure, said diaphragm is displaced axially within said casing toward said one chamber to cause a switch signal representative of the occurrence of said axial force to be given at said terminal means; and

said orifice means comprising control orifice means through which gas is driven from said one chamber as said diaphragm is being displace toward said one chamber, said control orifice means serving to impart dampening to the motion of said diaphragm toward said terminal means.

9. An inertia switch structure as set forth in claim 8 in which said diaphragm is constructed so as to be inherently biased in the axial direction away from said terminal means.

10. An inertia switch structure as set forth in claim 9 in which said diaphragm includes a mass that is carried centrally by said diaphragm on the face thereof that is toward said other chamber, said orifice means also passing through said mass.

11. An inertia switch structure as set forth in claim 10 including a stop for engaging said mass to set a limit for the extent to which said diaphragm is biased away from said terminal means.

12. An inertia switch structure as set forth in claim 9 including means acting between said casing and said diaphragm to form a stop that limits the extent to which said diaphragm is biased away from said terminal means.

13. An inertia switch structure as set forth in claim 8 in which said orifice means is arranged to communicate said one chamber to said other chamber so that gas from said one chamber is forced through said orifice means into said other chamber as said diaphragm is axially displaced toward said terminal means.