MASTER CYLINDER FLUID LEVEL INDICATOR

• US 3,603,926 A
• Filed: 06/20/1968
• Issued: 09/07/1971
• Est. Priority Date: 06/20/1968
• Status: Expired due to Term

• Current Assignee: Jack A. Kimura
• Original Assignee: Jack A. Kimura
• Inventors: Kimura, Jack A.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Cohen, Howard S.
• Application Number:
  US04/738,644
• Time in Patent Office: 1,174 Days
• Field of Search: 340/59,60,244,282 200/84 60/54.6
• US Class Current: 340/450.1
• CPC Class Codes: B60T 17/225 brake fluid level indicators level indication in general G01F; H01H
• CPC Class Codes: G01F 23/74 for sensing changes in level only at discrete points
• CPC Class Codes: H01H 36/02 actuated by movement of a float carrying a magnet

Abstract

A fluid indicator for closing an electrical circuit upon the approach of a low liquid level in a brake master cylinder reservoir employing a pair of resilient contacts within a switch housing with one of the contacts in electrical connection with the housing and another of the contacts in electrical connection with a connector terminal which are activated by a magnet within a float means which is positioned by the liquid level in the reservoir and including provisions to eliminate the effect of liquid motion in the reservoir on the operation of the switch.

Claims

1. In a master cylinder for use in a vehicle hydraulic braking system:

an electrically conductive housing connected to an electrical ground, said housing defining a bore therewithin and having an annular wall defining a fluid reservoir having an open upper end;

said reservoir being in fluid communication with said bore;

piston means slidably mounted in said bore for pressurizing fluid communicated from the reservoir to the bore when a brake application is effected;

an electrically conductive removable closure member for closing the open upper end of said reservoir;

a releasable retaining device for releasably securing said closure member to said housing;

an electrically conductive, tubular member carried by said cover member and electrically connected therewith, said tubular member extending vertically with respect to the cover member, one end of said tubular member extending downwardly with respect to the cover member into said fluid reservoir;

said tubular member and said cover member being removable as a unit from said housing when said releasable retaining device is released;

an electrical terminal carried by the other end of said tubular member and insulated electrically from the latter, said terminal being connected to a warning device, a source of electrical energy, and an electrical ground;

magnetically operated switch means housed within said tubular member and having a pair of contact elements;

one of said elements being connected to said terminal, the other element being connected to said tubular housing;

an annular float circumscribing said tubular member within said reservoir and adapted to move vertically within the latter in response to variations in the level of the fluid content of the reservoir;

stop means on said one end of said tubular member to prevent said float from falling off of said tubular member when the tubular member is removed from the reservoir; and

a magnet mounted on said float;

said magnet closing said switch means when the level of the fluid content of the reservoir falls to a level disposing the magnet in a position wherein the magnetic field of the latter envelopes said contacts.