System and method for sensing pedal rod to piston rod gap in a brake boost assist system of a master cylinder

A brake boost assist system for use with a master cylinder of a motor vehicle braking system, the brake boost assist system comprising:

• an inductive sensing system for detecting an axial pedal gap between faces of an input rod and an output rod of the brake boost assist system, the inductive sensing system including:
• an AC input signal source for generating an AC input signal;
• a first fixedly mounted coil disposed within the brake boost assist system;
• a second fixedly mounted coil disposed within the brake boost assist system and circumscribed by the first fixedly mounted coil, one of the first and second fixedly mounted coils receiving the AC input signal;
• an axially movable input member operably associated with the input rod, which is in turn associated with a brake pedal of the vehicle, and wherein the input member is movable in response to movement of the input rod and further being movable in proximity to the first and second fixedly mounted coils, the axially movable input member including an input member coil;
• an output member generally axially aligned with the input member and adapted to be moved axially by the input member, the output member being operably associated with the output rod of the brake boost assist system and including an input member coil;
• the input and output member coils further being arranged to at least partially overlap one another during movement of the input and output rods;
• a degree of overlap of the input and output member coils during movement of at least one of the input and output rods influencing an inductive coupling between the first fixedly mounted coil and the second fixedly mounted coil;
• and
• the one of the first and second fixedly mounted coils that is not receiving the AC input signal providing an output signal representing the axial pedal gap during brake pedal travel.

A brake boost assist system for use with a master cylinder of a motor vehicle braking system, the brake boost assist system comprising:

• an inductive sensing system for detecting an axial pedal gap between faces of an input rod and an output rod of the brake boost assist system, the inductive sensing system including:
• an LC oscillator circuit;
• a coil fixedly disposed within the brake boost assist system which receives an AC signal from the LC oscillator circuit;
• an axially movable input member operably associated with the input rod, which is in turn associated with a brake pedal of the vehicle, and wherein the input member is movable in response to movement of the input rod and further being movable in proximity to the coil;
• an output member generally axially aligned with the input member and adapted to be moved axially by the input member, the output member being operably associated with an output rod of the brake boost assist system;
• one of the input and output members including a metallic sensing member and the other including spaced apart, fixed metallic sensing elements;
• the metallic sensing member and the metallic sensing elements further being arranged to simulate the axial pedal gap separating the faces of the input and output rods;
• and
• the inductive sensing system being responsive to movement of at least one of the input member and the output member relative to the other, which changes a degree of overlap of the metallic sensing member relative to the metallic sensing elements, which causes a change in frequency of an output signal from the LC oscillator circuit, the output signal being indicative of a distance representing the axial pedal gap during brake pedal travel.

A method for sensing a pedal gap within a brake boost assist system associated with a master cylinder of a braking system of a motor vehicle, the method comprising:

• arranging a fixedly mounted sensing component within the brake boost assist system;
• coupling an axially movable input member to an input rod of the brake boost assist system, the input rod in turn being associated with a brake pedal of the vehicle, and wherein the input member is movable in response to movement of the input rod and further being movable in proximity to the fixedly mounted sensing component, the axially movable input member including a first sensing device;
• coupling an output member to an output rod of the brake boost assist system, the output member further being generally axially aligned with the input member and moveable axially by the input member, and carrying a second sensing device;
• forming an inductive circuit with the first and second sensing devices and the fixedly mounted sensing component;
• and
• generating a signal with the inductive circuit indicative of a distance representing an axial pedal gap separating faces of the input member and the output member during brake pedal travel in response to movement of at least one of the first sensing device, the second sensing device and the fixedly mounted sensing component.