Electro-hydraulic actuator for brake

An electro-hydraulic actuator for actuating a brake with a hydraulic thrust unit, the actuator comprising:

• an electric motor with a drive shaft,
• a converting mechanism connected with the drive shaft and adapted to convert a rotational motion of the drive shaft into a translational motion of a translatable portion,
• a cylinder and a piston received in the cylinder and constrained to the translatable portion so as to translate together with respect to the cylinder along a piston stroke extending from a rear end of stroke to a front end of stroke, wherein the piston stroke has a length and comprises:
• a front length including the front end of stroke and having a length less than or equal to half the length of the piston stroke, and
• a rear length including the rear end of stroke and having a length less than or equal to half the length of the piston stroke,
• a pressure chamber defined by the cylinder and the piston and having a volume that varies as a function of the piston position, from a maximum volume when the piston is at the rear end of stroke position to a minimum volume when the piston is at the front end of stroke position,
• a supply duct in communication with said pressure chamber and adapted to be connected with the hydraulic thrust unit of the brake, wherein the converting mechanism is configured so that, for a given angular speed of the drive shaft, a translation speed of the piston decreases from a maximum value in a position of the piston in the rear length to a minimum value in a position of the piston in the front length,
• wherein the converting mechanism comprises a crank and connecting rod mechanism having:
• a crank rotatable around a crank axis transversal to a translation axis of the piston, and
• a connecting rod having a first end hinged to the crank about a hinge axis in an eccentric point relative to the crank axis, a second end forming the translatable portion and permanently engaging a rear portion of the piston, and a length comprising a distance between the first end and the second end,
• wherein the crank axis is arranged at a perpendicular distance from the translation axis of the piston,
• wherein
• said crank has a radius defined as a distance between the crank axis and the hinge axis of the first end of the connecting rod, and said perpendicular distance is less than the radius of the crank, and
• said perpendicular distance ranges from 0.4L to 0.6L, where L is the length of the connecting rod.