AUTOMOTIVE INERTIA SWITCH WITH DASHPOT TYPE ACTUATOR

• US 3,793,498 A
• Filed: 04/27/1972
• Issued: 02/19/1974
• Est. Priority Date: 04/27/1971
• Status: Expired due to Term

• Current Assignee: Kenzo Hirashima, Shunji Matsui, Yoshikazu Hayakawa
• Original Assignee: Kenzo Hirashima, Shunji Matsui, Yoshikazu Hayakawa
• Inventors: Matsui, Shunji, Hayakawa, Yoshikazu, Hirashima, Kenzo
• Primary Examiner(s): Scott, James R.
• Application Number:
  US05/248,241
• Time in Patent Office: 663 Days
• Field of Search: 200/34,61.08,61.45R,61.53,81.9R,81.9M,82R,86.5 335/59,61
• US Class Current: 200/61.45R
• 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 35/142 Damping means to avoid unwanted response

Abstract

Herein disclosed is a mechanical pressure switch device which serves not only as a support mechanism for a bumper of a motor vehicle but as a combination impact detector and switch which is actuated in response to a frontal or rear-end collision encountered by the motor vehicle, comprising in one preferred form a cylinder, a piston axially slidable in the cylinder bore and dividing the cylinder bore into two chambers which are in communication with each other through an orifice formed in the piston, pressure absorptive means such as liquid filling the chambers in the cylinder, and switch means which is actuated in response to the axial movement of the plunger relative to the cylinder through a predetermined distance. The pressure absorptive means may include an incompressible or compressible fluid or an elastic or resilient material in the chamber or chambers in the cylinder. The switch device is connected at one end to the bumper and at the other to a suitable structural member of the vehicle body.

Claims

1. A switch device responsive to impact forces, comprising:

a cylinder closed at one end by an end wall and having an annular plug at the opposite end;

a piston slidable in said cylinder to divide the cylinder bore into a first compartment adjacent said end plug and a second compartment adjacent said end wall;

a plunger fixed to said piston and extending through said second compartment and slidably mounted in said annular end plug and terminating at the exterior of said cylinder;

a liquid filling said first and second compartments;

orifice means in said piston for regulating the flow of liquid from said first compartment to said second compartment to regulate the speed at which said plunger may be moved inwardly into the cylinder bore when subjected to impact forces; and

a switch means responsive to a predetermined inward movement of said plunger into said cylinder by impact forces thereon.

2. A switch device as claimed in claim 1, wherein said switch means comprises:

a first electrical contact mounted on the exterior portion of said plunger adjacent to and exteriorly of the end of said cylinder opposed to said end wall and substantially stationary with respect to said cylinder; and

a second electrical contact attached to the exterior portion of said plunger and spaced axially away from the end of said cylinder opposed to said end wall and substantially in axial alignment with said first contact for contact therewith when said plunger is subjected to impact forces.

3. A switch device as claimed in claim 1, wherein said plunger has an axial cavity closed at the end adjacent to said piston by an annular sealing member, said switch device further comprising a contact support member in the form of a rod extending axially from said end wall through said first compartment and said annular sealing member a first electrical contact attached to the leading end portion of said rod adjacent to said annular sealing member within said cavity and a second electrical contact attached to the inner wall of said cavity in said plunger and normally spaced axially apart from said first contact and said annular sealing member.

4. A switch device as claimed in claim 1, wherein said switch means comprises an annular electrically insulative deformable member surrounding the outer peripheral wall of the exterior portion of said plunger and spaced apart from the end of said cylinder opposed to said end wall, said annular material having a cavity therein, two electrical contacts disposed within said cavity normally spaced axially apart from each other with respect to the axis of said plunger.

5. A switch device as claimed in claim 1, wherein said switch means comprises a rupturable, electrically conductive means which is rupturable when subjected to impact forces greater than a predetermined magnitude, said rupturable electrically conductive means being securely mounted on an outwardly projecting portion of said plunger for being ruptured against the opposite end of said cylinder when said plunger is moved inwardly into said cylinder through a predetermined distance by impact forces.

6. A switch device as claimed in claim 5, wherein said rupturable electrically conductive means includes a rupturable piece of glass coated with an electrically conductive film.

7. A switch device as claimed in claim 1, wherein said switch means comprises a rupturable, electrically conductive means which is rupturable when subjected to impact forces greater than a predetermined magnitude, a presser member mounted on the outer periphery of an outwardly projecting portion of said plunger, said rupturable, electrically conductive means being mounted at the end of said cylinder opposed to said end wall and normally spaced from and substantially in axial alignment with said presser member for being struck and ruptured by said presser member when said plunger is moved inwardly by impact forces into said cylinder toward the closed end wall thereof through a predetermined distance.

8. A switch device as claimed in claim 1, wherein said switch means comprises a receptacle having a cavity formed therein and mounted in the wall of said first compartment of said cylinder, a plug member slidable in said cavity in the receptacle and having an outer face in contact with said liquid in said first compartment, said receptacle and said plug member having electric contacts on their inner facing walls, and biasing means urging said plug member outwardly from said receptacle against the pressure of said liquid acting on the outer face of said plug member for biasing said electric contacts away from each other, said plug member being moved against the force of said biasing means for allowing said electric contacts to be forced against each other when said liquid is subjected to a pressure in response to the axial movement of said plunger by impact forces toward said closed end wall of said cylinder through a predetermined distance.

9. A switch device as claimed in claim 8, wherein said receptacle and said plug member are formed of an electrically conductive material and in which said electric contacts are formed integrally with said receptacle and said plug member and are aligned with each other within said cavity of said receptacle and further comprising means for electrically insulating said receptacle and said plug means from each other when in the normal inoperative position.

10. A switch device as claimed in claim 11, and further comprising a free piston sealingly slidable within the first compartment of said cylinder to define a third compartment cooperating with said closed end wall;

and a compressible gas filling said third compartment.

11. A switch device as claimed in claim 10, wherein said switch means comprises a receptacle having a cavity formed therein and mounted in the wall of said third compartment of said cylinder, a plug member slidable in said cavity in said receptacle and having an outer face in contact with the gas in said third compartment, said receptacle and said plug member having electric contacts on their inner facing walls, and biasing means urging said plug member outwardly from said receptacle against the pressure of the gas acting on the outer face of said plug member for biasing said electric contacts away from each other, said plug member being moved against the force of Said biasing means for allowing said electric contacts to be forced against each other when said gas is subjected to a pressure in response to the axial movement of said plunger by impact forces toward said closed end wall of said cylinder through a predetermined distance.

12. A switch device as claimed in claim 11, wherein said receptacle and said plug member are formed of an electrically conductive material and in which said electric contacts are formed integrally with said receptacle and said plug member and are aligned with each other within said cavity of said receptacle and further comprising means for electrically insulating said receptacle and said plug from each other when in the normal inoperative position.

13. A switch device as claimed in claim 10, wherein said switch means comprises a magnet attached to the end of said cylinder opposed to said end wall to surround said plunger;

and a solenoid coil attached to the exterior of said plunger in substantial axial alignment with said magnet and axially spaced apart from the end of said cylinder.

14. A switch device as claimed in claim 1, wherein said cylinder includes a tapered rod secured to the end wall of said cylinder and extending axially within said cylinder through said piston, and said switch means comprises a magnet mounted on said piston and a solenoid coil wound on said rod within said first compartment and normally spaced axially from said piston.

15. A switch device as claimed in claim 14, wherein said orifice regulating means comprises an aperture in said piston through which said tapered rod extends in spaced relation, said tapered rod and said aperture forming the flow regulating orifice.