Magneti Marelli S.p.a.

Magneti Marelli Powertrain, S.p.a.

Stefano Giorgini

Luca Bovina

Marcello Lorenzoni

Andrea Bersani

Nerio Mengoli

A hydraulic servo-control of a servo-controlled gearbox comprises hydraulic actuators defining chambers, a storing tank containing control fluid used by the actuators at room pressure, a hydraulic accumulator containing control fluid under pressure, a motor pump drawing the fluid from the tank and feeding it under pressure to the accumulator, and solenoid valves selectively connecting the chambers to the tank and accumulator. The accumulator includes an outer housing defining an inner cylindrical surface defining a first diameter, a piston arranged and axially slidable and mobile inside the housing and defining there a first variable-volume chamber for a gas and second variable-volume chamber for the fluid under pressure, and a limit stopper arranged at an open end of the housing, acting as a striker for the piston, and having an annular circlip defining an opening and overall second diameter approximating by excess the first diameter of the surface of the housing.

Hydraulic servo-control of a servo-controlled gearbox

A hydraulic servo-control of a servo-controlled gearbox provided with a hydraulic accumulator, having an outer housing and a piston that is slidable axially inside the outer housing and adapted to define a first variable-volume chamber for a gaseous material and a second variable-volume chamber for a control fluid under pressure; and at least one limit stop arranged at an open end of the outer housing which serve as a lower limit stop element; wherein the outer housing is provided with an upper limit stop element, which acts to limit the pressure value inside the first variable-volume chamber within a predetermined safety range.

A method of controlling an electro-actuated clutch in an internal combustion engine, the clutch including a clutch mechanism, an electric motor for actuating the clutch mechanism, and a mechanical transmission, which is interposed between the electric motor and the clutch mechanism. During a manufacturing phase of the system, a detachable connection is established in the mechanical transmission, wherein a first element simply rests on a second element to divide the electro-actuated clutch into a first part, arranged upstream of the detachable connection, and a second part, arranged downstream of the detachable connection. During operation, a first position signal generated by a first position sensor mechanically connected to a point of the first portion of the electro-actuated clutch is read, as is a second position signal generated by a second position sensor mechanically connected to a point of the second portion of the electro-actuated clutch. The first position signal is compared with the second position signal. A position in which the first position signal starts differing from the second position signal is recognized, and an estimate made of a closing position of the clutch mechanism coinciding with the position in which the first position signal starts differing from the second position signal.

Method of controlling an electro-actuated clutch for determining the closing position

A hydraulically servocontrolled transmission for a road vehicle provided with an internal combustion engine; the servocontrolled transmission displays: a servocontrolled mechanical gearbox operated by at least one first hydraulic actuator; a servocontrolled clutch operated by at least one second hydraulic actuator; a hydraulic circuit comprising a hydraulic accumulator, which contains pressurised control fluid which is used by the hydraulic actuators, and a pump, which is directly operated by the internal combustion engine to supply pressurised control fluid to the hydraulic accumulator; a park-lock device operatable to block the rotation of the driving wheels; and a control unit, which, when the internal combustion engine is turned off, uses the remaining pressure of the control fluid within the hydraulic accumulator to bring the servocontrolled mechanical gearbox in a neutral position.

Hydraulically servocontrolled transmission for a road vehicle provided with an internal combustion engine

Described herein is a hydraulic servo for a gear change provided with a control shaft; the servo has: a frame; a first hydraulic actuator, which is carried by the frame and has two first chambers, which are alternatively filled with a pressurized fluid for displacing the control shaft axially in the two directions; two first solenoid valves, which control filling of the two first chambers; a second hydraulic actuator, which is carried by the frame and has at least one second chamber that is filled with a pressurized fluid for rotating the control shaft about its central axis; a second solenoid valve, which controls filling of the second chamber; and a supporting body, which is fixed to the frame, houses the solenoid valves, and has inside it a series of hydraulic circuits, which connect the solenoid valves themselves both to the chambers of the actuators and to a supply of the pressurized fluid.

Hydraulic servo for a gear change

Described herein is a servo for a gear change provided with a control shaft; the servo has: a first actuator, which displaces the control shaft axially along a central axis thereof and is directly coupled to the control shaft; and a second actuator, which renders a cam engaged by a pin projecting from the control shaft angularly fixed to a fixed frame to cause rotation of the control shaft about its central axis during the axial displacement; a cylindrical tubular element is provided, which is coaxial to the control shaft, receives inside it an end portion of the control shaft, supports the cam, and is pushed axially by the second actuator against the fixed frame.

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Minerbio, Italy

Stefano Giorgini