STEPPER MOTOR DRIVING ASSEMBLY WITH POSITIVE BRAKE

• US 20030184177A1
• Filed: 04/02/2002
• Published: 10/02/2003
• Est. Priority Date: 04/02/2002
• Status: Active Grant

• Current Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Enzinna, Donald John
• Granted Patent: US 6,642,636 B2
• Time in Patent Office: Days
• US Class Current: 310/93
• CPC Class Codes: H02K 7/102 with friction brakes
• CPC Class Codes: H02K 7/116 with gears
• CPC Class Codes: H02K 7/125 magnetically influenced

Abstract

An automatically acting braking system for a stepper motor (10) of the type having a rotor (18) that is radially centered within a stationary stator (12) and which rotates about the central axis of a central shaft (30). The rotor (18) is allowed to axially slide back and forth, biased in one direction continually by a resilient means (40). When the stator (12) is energized, it pulls the rotor (18) to an axially centered position within stator (12), but when it is de energized, the resilient means (40) pushes the rotor (18) to one side, lockingly engaging its teeth (24) with the teeth (44) of a fixed locking ring (42).

Claims

1. An automatically acting braking system for a stepper motor (10) of the type having a rotor (18) that is located within a stationary stator (12) and which rotates about the central axis of a central shaft (30) when the stator is energized, and which is forcibly held in an axially centered position within the stator (12) when the stator (12) is energized, and which takes on a substantially stable, pre determined angular alignment relative the stator (12) when the stator (12) is energized, said braking system characterized by,

a sliding means (32) allowing toothed rotor (18) to move axially back and forth along the central axis of central shaft (30) while remaining radially centered within stator (12),

a resilient means (40) sufficiently strong to bias the rotor (18) in one axial direction along the central axis of central shaft (3) and away from its axially centered position when the stator (12) is not energized, but sufficiently weak to be overcome by the axial centering force acting on the toothed rotor (18) when the stator (12) is energized.

and a locking member (42) fixed relative to the stator (12) in a position that allows it to register with and automatically lockingly engage with the rotor (18) when the stator (12) is de energized and the rotor (18) is pushed in one axial direction by the resilient means (40).

2. An automatically acting braking system for a stepper motor (10) according to claim 1, further characterized in that:

the sliding means (32) is a plain bearing that allows central shaft (30) to slide back and forth along its central axis.

3. An automatically acting braking system for a stepper motor (10) according to claim 1, further characterized in that:

the locking member (42) is a ring that has teeth (44) located so as to register with and engage complementary teeth (24) on rotor (18) when the stator (12) is de energized.

4. An automatically acting braking system for a stepper motor (10) according to claim 1, further characterized in that:

the resilient means (40) is a coil spring that acts in tension to continually bias the rotor (18) and the shaft (30) in one axial direction.