Piston pump assembly comprising piston with variable stroke and vehicle braking system comprising the same

A piston pump assembly comprising a piston with a variable stroke for use in a hydraulic braking system, comprising:

• a rotatable drive shaft defining an axis of rotation of the rotatable drive shaft;
• a cam disposed on the drive shaft;
• and
• a piston biased toward the cam and configured to reciprocate along a piston axis for displacing a hydraulic fluid,
• wherein the cam is configured to transform a rotating movement of the drive shaft into a linear movement of the piston,
• wherein the cam is movable relative to the piston axis and configured to be selectively placed in a first position at a first distance from the piston axis or a second position at a second distance from the piston axis,
• wherein the cam comprises at least two portions each of which has, at a given position of the cam relative to the piston axis, at least one of a different non-circular cross section in a plane perpendicular to the axis of rotation or a different eccentricity with respect to the axis of rotation,
• wherein the at least two portions of the cam comprises at least a first cam portion having a first non-circular cross section and/or a first eccentricity, and a second cam portion having a second non-circular cross section and/or a second eccentricity,
• wherein the cam and the piston are configured such that, when the cam is placed in the first position at the first distance from the piston axis, the cam drives the piston through the first cam portion, resulting in a piston movement having a first stroke,
• wherein the cam and the piston are configured such that, when the cam is placed in the second position at the second distance from the piston axis, the cam drives the piston through the second cam portion, resulting in a piston movement having a second stroke different from the first stroke,
• wherein the first stroke associated with the first cam portion is smaller than the second stroke associated with the second cam portion, and
• wherein the piston pump assembly further comprises a biasing member, the biasing member comprising an elastic member including a spring, and the biasing member biasing the cam toward the first position relative to the piston axis in which the cam is configured to drive the piston through the first cam portion associated with the first stroke.