Coupling device for connecting a brake input element to a main brake cylinder and method for operating such a coupling device

A coupling apparatus for connecting a braking input element to a brake master cylinder of a vehicle, comprising:

• an input piston disposed on the braking input element in such a way that upon actuation of the braking input element, the input piston is displaced out of an initial position over a brake application distance;
• and
• an output piston to which a driver braking force exerted onto the braking input element is transferred via the input piston displaced out of the initial position over at least one predefined first minimum brake application distance, the output piston being disposed on the brake master cylinder in such a way that an internal pressure in the brake master cylinder is increased by way of the driver braking force transferred via the input piston to the output piston;
• wherein, at least in a first operating mode of the coupling apparatus, the input piston displaced out of the initial position over a brake application distance less than the predefined first minimum brake application distance is spaced apart from the output piston in such a way that a force transfer from the input piston to the output piston is suppressed;
• wherein, at least in a second operating mode of the coupling apparatus having a predefined second minimum brake application distance less than the predefined first minimum brake application distance, the input piston displaced out of the initial position over a brake application distance less than the predefined second minimum brake application distance is spaced apart from the output piston in such a way that a force transfer from the input piston to the output piston is suppressed, and the driver braking force is transferred via the input piston displaced out of the initial position over a brake application distance between the predefined second minimum brake application distance and the predefined first minimum brake application distance, to the output piston.

A method for operating a coupling apparatus with which a braking input element is connected to a brake master cylinder of a vehicle, the coupling apparatus having (i) an input piston disposed on the braking input element in such a way that upon actuation of the braking input element, the input piston is displaced out of an initial position over a brake application distance, and (ii) an output piston to which a driver braking force exerted onto the braking input element is transferred via the input piston displaced out of the initial position over at least one predefined first minimum brake application distance, the output piston being disposed on the brake master cylinder in such a way that an internal pressure in the brake master cylinder is increased by way of the driver braking force transferred via the input piston to the output piston, the method comprising:

• operating the coupling apparatus in a first operating mode in which the input piston displaced out of the initial position over a brake application distance less than the predefined first minimum brake application distance is spaced apart from the output piston in such a way that a force transfer from the input piston to the output piston is suppressed;
• and
• selectively switching the coupling apparatus into at least a second operating mode having a second minimum brake application distance less than the first minimum brake application distance, wherein in the second operating mode the input piston displaced out of the initial position over a brake application distance less than the predefined second minimum brake application distance is spaced apart from the output piston in such a way that a force transfer from the input piston to the output piston is suppressed, and the driver braking force is transferred via the input piston displaced out of the initial position over a brake application distance between the predefined second minimum brake application distance and the predefined first minimum brake application distance, to the output piston.