| 摘要 |
<p>In a hydraulic brake system, a housing includes a brake master cylinder and a reservoir formed therein for containing a supply of brake fluid. A sensor piston in contact with the pressure in the brake master cylinder is connected to an indicator piston. The indicator piston is coaxial with a blind cylindrical indicator bore. The blind bore and indicator piston are in communication with the reservoir at a level below which the brake fluid should not be allowed to recede. When the brake is operated, brake master cylinder pressure urges the sensor piston outward. The connected indicator piston is urged toward the blind bore. If the reservoir contains fluid, the blind bore is filled with the fluid. Fluid lock of the indicator piston therefore occurs before any appreciable indicator piston motion into the blind indicator bore. On the other hand, if the reservoir, and the communicating indicator bore, are empty, the indicator piston is enabled to enter the indicator bore by compressing air therein. Motion of the indicator piston into the indicator bore actuates an electrical switch which energizes a warning indicator. Once fully actuated, the electrical switch is mechanically latched in the on position to provide a continued warning indication until it is manually reset after replenishing the brake fluid. In one embodiment of the invention, intermediate brake fluid levels cause the generation of momentary warning signals.</p> |
