FILTER CONDITION INDICATOR SYSTEM

• US 3,611,337 A
• Filed: 04/03/1969
• Issued: 10/05/1971
• Est. Priority Date: 04/03/1969
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: David J. Balzer, Lloyd L. Phelps Jr
• Inventors: Balzer, David J., Phelps, Lloyd L. Jr.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US04/813,159
• Time in Patent Office: 915 Days
• Field of Search: 340/239,213.1 55/DIG.34,274 200/78,83.6
• US Class Current: 340/607
• CPC Class Codes: B60R 16/0232 for measuring vehicle parameters and indicating critical, abnormal or dangerous conditions

Abstract

An indicator system suitable for indicating a defective fluid filter providing excess blockage to fluid flow, including an electrical switch assembly responsive to the defective operating condition, an indicator responsive to the switch for providing a warning signal and an electrically responsive lockout mechanism for maintaining the indicator in its warning condition.

Claims

1. An indicator system suitable for indicating a defective fluid filter providing excessive blockage of fluid flow, comprising a switch assembly capable of sensing a defective operating condition, the switch assembly having a normal operating position and being capable of shifting to another operating position upon sensing the faulty condition;

an electrically responsive indicator responsive to electrical current flow for providing a safe operating signal and otherwise providing a warning signal in the absence of current flow;

an electrically responsive lockout device comprising a thermal trip device including a heating element coupled in electric series circuit relation with the switch assembly and indicator and a stressed bimetallic member tending to remain in either an electrically closed position completing the circuit for the heating element, switch assembly and indicator or an electrically open position, thermal energy from the heating element causing the bimetallic member to assume its electrically open position;

means for selectively returning the bimetallic member to its electrically closed position; and

an electrical source for powering the circuit.

2. The invention of claim 1 wherein the circuit breaker is associated with the switch by parallel electrical paths, one path including the indicator, the other path providing a closed circuit with the switch effective to operate the circuit breaker when the switch is in its other operating position.

3. An indicator system suitable for indicating a defective fluid filter providing excessive blockage to fluid flow, comprising a switch assembly capable of sensing a defective operating condition, the switch assembly having a normal operating position and being capable of shifting to another operating position while sensing the faulty condition, an electrically responsive indicator associated with the switch, the indicator being conditioned to provide a warning signal in response to the switch being placed in its other operating position, an electrically responsive lockout device associated with the indicator and switch, the lockout device being effective to maintain the indicator in its condition providing a warning signal upon shifting of the switch to its other operating position. and

4. The inventiOn of claim 1 wherein the switch assembly includes pressure-sensitive means arranged in communication with a fluid filter line and switch means responsive to the pressure sensitive means.

5. The invention of claim 1 wherein the switch assembly includes a differential pressure-sensitive piston in a bore formed by a housing, portions of the housing being in respective communication with an inlet conduit and an outlet conduit for a fluid filter.

6. The invention of claim 5 further comprising a magnet supported by the piston, magnetically responsive switch means arranged outside of the housing for operation by the magnet, the housing being nonmagnetic.

7. The invention of claim 5 further comprising a spring arranged to resist movement of the piston by fluid pressure from the inlet conduit, strength of the spring being generally equivalent to a maximum safe operating pressure differential across the filter.