Actuator with a non-contact position sensor

• US 20070245890A1
• Filed: 04/05/2007
• Published: 10/25/2007
• Est. Priority Date: 04/06/2006
• Status: Active Grant

• Current Assignee: Magneti Marelli Powertrain S.p.A. (Magneti Marelli S.p.A.)
• Original Assignee: Magneti Marelli Powertrain S.p.A. (Magneti Marelli S.p.A.)
• Inventors: Baldassari, Andrea, Dragoni, Eugenio, Bellato, Nazario, Colli, Marcello
• Granted Patent: US 7,759,930 B2
• Time in Patent Office: Days
• US Class Current: 92/5.R
• CPC Class Codes: F15B 15/063 Actuator having both linear and rotary output, i.e. dual action actuator
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F16H 59/70 dependent on the ratio established
• CPC Class Codes: F16H 61/28 with at least one movement of the final actuating mechanism being caused by a non-mechanical force, e.g. power-assisted

Abstract

An actuator having a fixed part, a movable part movable with respect to the fixed part in a travelling direction, and a non-contact position sensor connected to the movable part to read the position of the movable part. The position sensor has a reading device connected to the fixed part and having a ferromagnetic core; and a magnetic cursor, which is integrated in the movable part, is defined by a magnetized portion of the movable part, and is so magnetized as to locally saturate the ferromagnetic core at the magnetic cursor.

Claims

1. An actuator comprising:

a fixed part;

a movable part movable with respect to the fixed part in a travelling direction; and

a non-contact position sensor connected to the movable part to read the position of the movable part, the non-contact position sensor comprising a reading device and a magnetic cursor, the reading device being connected to the fixed part and to a ferromagnetic core, the magnetic cursor being connected to the movable part and magnetized so as to locally saturate the ferromagnetic core at the magnetic cursor,

wherein the magnetic cursor is integrated in the movable part and is defined by a magnetized portion of the movable part.

2. The actuator as claimed in claim 1, wherein the reading device comprises a primary coil and two identical secondary coils, the primary coil being wound along the whole of the ferromagnetic core, and the two identical secondary coils being wound about the two ends of the ferromagnetic core and being connected to each other in series so that the magnetic fluxes generated by the two identical secondary coils are in phase opposition.

3. The actuator as claimed in claim 2, wherein the reading device comprises:

an alternating voltage generator connected to terminals of the primary coil; and

a voltmeter connected to terminals of the two identical secondary coils.

4. The actuator as claimed in claim 2, wherein the reading device comprises:

an alternating voltage generator connected to terminals of the two identical secondary coils; and

a voltmeter connected to terminals of the primary coil.

5. The actuator as claimed in claim 1, wherein the movable part comprises a control shaft of a transmission, and wherein the moveable part moves axially along a central axis of the control shaft.

6. The actuator as claimed in claim 5, further comprising two chambers that are configured to be alternately filled with a pressurized fluid to move the control shaft axially in both directions along the central axis, wherein the two chambers are fitted through with the control shaft, located in series along the control shaft, are separated by a flange integral with the control shaft, and define a piston of the actuator.

7. A servocontrol for a transmission, comprising:

an actuator having a fixed part, a movable part, and a non-contact position sensor,

wherein the movable part is movable with respect to the fixed part in a travelling direction and the non-contact position sensor is connected to the movable part to read the position of the movable part, the non-contact position sensor comprising a reading device and a magnetic cursor, the reading device being connected to the fixed part and to a ferromagnetic core, the magnetic cursor being connected to the movable part and magnetized so as to locally saturate the ferromagnetic core at the magnetic cursor, and

wherein the magnetic cursor is integrated in the movable part and is defined by a magnetized portion of the movable part.