Low tire pressure indicating device

• US 3,938,078 A
• Filed: 01/08/1975
• Issued: 02/10/1976
• Est. Priority Date: 01/08/1975
• Status: Expired due to Term

• Current Assignee: Plant; Z. Y., R Davis, W Tribbey
• Original Assignee: Plant; Z. Y., R Davis, W Tribbey
• Inventors: Davis, Raymond D., Plant, Z. Y. Jr.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/539,388
• Time in Patent Office: 398 Days
• Field of Search: 340/58, 200/61.22, 200/61.25
• US Class Current: 340/442
• CPC Class Codes: B60C 23/04 mounted on the wheel or tyre
• CPC Class Codes: B60C 23/0496 Valve stem attachments positioned outside of the tyre chamber

Abstract

A device adapted to be directly connected to the valve stem of automobile tires to indicate a low pressure condition. The device comprises a light, a battery, and a compressionable spring switch assembly uniquely responsive to a low pressure condition in the tires for operating the switch assembly thereby connecting an electrical circuit to energize the bulb. A fail-safe feature immediately prevents the loss of fluid pressure from the tire being measured should the device be damaged either maliciously or by road hazards. The low pressure signals indicated by an energized light are adapted to be seen by the driver through suitably placed mirrors located on the vehicle.

Claims

1. A low fluid presssure indicating system comprising:

a plunger adapted to fit into and open a pressure valve assembly for releasing fluid pressure,

a first moveable piston attached to said plunger and moveable by said releasing fluid pressure,

a light assembly comprising a battery, a bulb, and a compressionable spring switch assembly electrically connected in series with each other,

said compressionable spring switch assembly providing a closed electrical path for energizing said bulb in the normal position and an open electrical path for extinguishing said bulb in the compressed position,

a second moveable piston contacting said compressionable spring switch assembly for compressing said spring switch assembly to close said electrical circuit and extinguish said bulb, and

a flexible liquid filled tube connected at one end to said first moveable piston and at the other end to said second moveable piston whereby escaping fluid pressure moves said first piston causing pressure on said liquid in said tube to move against said second piston for operating said compressionable spring switch assembly.

2. A system according to claim 1 in which said first moveable piston is located in a first cylinder for accepting said releasing fluid pressure and in which maximum travel of said piston is limited by the length of said plunger.

3. A system according to claim 2 in which said first cylinder is sealed, completely entrapping and holding all of said releasing fluid pressure.

4. A system according to claim 1 in which said light assembly holds said bulb, said battery, and said compressionable spring switch assembly in a coaxial relationship.

5. A system according to claim 1 which includes a second cylinder located in said light assembly and consists of a first portion that is electrically non-conducting and a second portion that is electrically conductive.

6. A system according to claim 5 in which said compressionable spring switch assembly is located in said second cylinder and includes a compression spring circular at one end for contacting said second piston and in which the opposite end of said compression spring terminates in a point penetrating said first portion of said second cylinder for contacting a terminal of said battery.

7. A system according to claim 6 in which said compression spring electrically contacts the walls of said second cylinder and in which compression of said spring by said second cylinder causes said spring to alternately contact said second portion and said first portion of said cylinder wall.

8. A system according to claim 5 in which said first portion is the base portion and part wall portion of said second cylinder and said second portion is all wall portion of said second cylinder.

9. A system according to claim 1 in which said flexible tube is a rubber tube filled with hydraulic fluid.

10. A system according to claim 1 in which said light assembly comprises

a chamber for holding said battery and said bulb in coaxial contacting alignment,

a cylinder located immediately below and separated from said battery by an electrically non-conducting insert formed at the base portion of said cylinder,

the remaining wall portion of said cylinder formed from an electrically conductive material.

11. A system according to claim 10 in which said compressionable spring switch assembly consists of a spring located within said cylinder and adapted to electrically contact said electrically conductive wall material of said cylinder as said spring is moved.