Position detecting apparatus for actuator and variable valve lift mechanism for internal combustion engine

• US 20050258823A1
• Filed: 04/01/2005
• Published: 11/24/2005
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kinoshita, Yasuo
• Granted Patent: US 7,215,113 B2
• Time in Patent Office: Days
• US Class Current: 324/207.230
• CPC Class Codes: F01L 1/34 characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
• CPC Class Codes: F01L 1/34406 the helically teethed sleeve being located in the camshaft driving pulley
• CPC Class Codes: F01L 13/00 Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
• CPC Class Codes: H02K 29/08 using magnetic effect devices, e.g. Hall-plates, magneto-resistors H02K29/12 takes precedence

Abstract

A position detecting apparatus for an actuator includes a linear movement mechanism in which a magnet is provided; a coil which is provided so as to face the magnet such that a magnetic field is formed between the coil and the magnet; and a drive shaft which is connected to the linear movement mechanism through a ball screw, and which is linearly moved in response to rotational movement of the rotor, the rotational movement being caused by energizing the coil; and a magnetic flux detection sensor which detects a change in magnetic flux of the magnet, the change being caused by the rotational movement of the rotor, and which obtains an amount of linear movement of the drive shaft based on the detected change in the magnetic flux.

Claims

1. A position detecting apparatus for an actuator, comprising:

a rotor in which a magnet is provided;

a coil which is provided so as to face the magnet such that a magnetic field is formed between the coil and the magnet;

a shaft which is connected to the rotor through a movement conversion mechanism that converts rotational movement to linear movement, and which is linearly moved in response to rotational movement of the rotor, the rotational movement being caused by energizing the coil; and

a sensor portion which detects a change in magnetic flux of the magnet, the change being caused by the rotational movement of the rotor, and which obtains an amount of linear movement of the shaft based on the detected change in the magnetic flux.

2. The position detecting apparatus according to claim 1, wherein the coil and the magnet extend in a predetermined direction from a position close to the sensor portion to a position far from the sensor portion, and the sensor portion is closer to a center position of the magnet in the predetermined direction than to a center position of the coil in the predetermined direction.

3. The position detecting apparatus according to claim 1, wherein the coil and the magnet extend in a first direction in which the shaft is moved, and the sensor portion is closer to a center position of the magnet in the first direction than to a center position of the coil in the first direction.

4. The position detecting apparatus according to claim 1, wherein the magnet is buried in the rotor so as to be exposed on a side of the rotor, the side facing the sensor portion.

5. The position detecting apparatus according to claim 1, wherein when the rotor is rotated, an amount of movement of a position where the magnet is provided per unit time is larger than an amount of movement of the shaft per unit time.

6. The position detecting apparatus according to claim 1, wherein the movement conversion mechanism is one of a ball screw and a feed screw.

7. The position detecting apparatus according to claim 1, wherein the magnet has a bar shape, the sensor portion is separated from the magnet, and the sensor portion is provided so as to face the magnet while the rotor is rotated.

8. A variable valve lift mechanism for an internal combustion engine, characterized by comprising:

the position detecting apparatus according to claim 1.