Lift and hold differential lift PDU utilizing a permanent magnet rotor

Patent metadata

Field	Value
Publication number	US-9878789-B2
Application number	US-201514937562-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 10, 2015
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

A power drive unit (PDU) for moving cargo relative to a cargo bay of an aircraft includes a cam shaft. The PDU also includes a lift cam coupled to the cam shaft and configured to cause the PDU to be in at least one of a raised position or a lowered position based on rotation of the cam shaft. The PDU also includes a permanent magnet motor configured to generate a cogging torque sufficient to resist rotation of the cam shaft such that the PDU remains in the raised position in response to power being removed from the permanent magnet motor.

First claim

What is claimed is:

1. A power drive unit (PDU) for moving cargo relative to a cargo bay of an aircraft, comprising:
a cam shaft;
a lift cam coupled to the cam shaft and configured to cause the PDU to be in at least one of a raised position or a lowered position based on rotation of the cam shaft;
a permanent magnet motor configured to generate a cogging torque sufficient to resist rotation of the cam shaft such that the PDU remains in the raised position in response to power being removed from the permanent magnet motor; and
a planetary gear set configured to be coupled to the permanent magnet motor and to the cam shaft such that mechanical power can transfer from the permanent magnet motor to the cam shaft via the planetary gear set and such that a gear ratio of the planetary gear set multiplies the cogging torque of the permanent magnet motor to generate reflected inertia.

2. The PDU of claim 1 , wherein the permanent magnet motor includes at least one of an interior permanent magnet motor, a surface permanent magnet motor or a brushless direct current (DC) motor.

3. The PDU of claim 1 , wherein the permanent magnet motor is configured to generate about 18 ounce-inches of cogging torque.

4. The PDU of claim 1 , further comprising an output shaft coupled to the permanent magnet motor and to the planetary gear set such that mechanical power can transfer from the permanent magnet motor to the output shaft via the planetary gear set.

5. The PDU of claim 4 , further comprising a drag clutch coupled to the planetary gear set and configured to control the coupling between the cam shaft and the planetary gear set and between the output shaft and the planetary gear set.

6. The PDU of claim 5 , further comprising a controller coupled to the permanent magnet motor and configured to control rotation of a rotor of the permanent magnet motor.

7. The PDU of claim 1 , wherein an entire gear set of the PDU has a gear ratio between 60 to 1 (60:1) and 85:1.

8. The PDU of claim 7 , further comprising a controller configured to determine an angular position of the PDU relative to a conveyor plane based on data detected by the rotary encoder.

9. The PDU of claim 1 , further comprising a rotary encoder and wherein the permanent magnet motor includes a rotor and a stator and the rotary encoder is configured to detect an angular position of the rotor relative to the stator.

10. A power drive unit (PDU) for moving cargo relative to a cargo bay of an aircraft, comprising:
a cam shaft;
a lift cam coupled to the cam shaft and configured to cause the PDU to be in at least one of a raised position or a lowered position based on rotation of the cam shaft;
a permanent magnet motor configured to generate a cogging torque sufficient to resist rotation of the cam shaft such that the PDU remains in the raised position in response to power being removed from the permanent magnet motor, the permanent magnet motor including a rotor and a stator;
a rotary encoder configured to detect an angular position of the rotor relative to the stator; and
a controller configured to determine an angular position of the PDU relative to a conveyor plane based on data detected by the rotary encoder.

11. The PDU of claim 10 further comprising a planetary gear set configured to be coupled to the permanent magnet motor and to the cam shaft such that mechanical power can transfer from the permanent magnet motor to the cam shaft via the planetary gear set and such that a gear ratio of the planetary gear set multiplies the cogging torque of the permanent magnet motor to generate reflected inertia.

12. The PDU of claim 11 further comprising an output shaft coupled to the permanent magnet motor and to the planetary gear set such that mechanical power can transfer from the permanent magnet motor to the output shaft via the planetary gear set.

13. The PDU of claim 12 further comprising a drag clutch coupled to the planetary gear set and configured to control the coupling between the cam shaft and the planetary gear set and between the output shaft and the planetary gear set.

14. The PDU of claim 10 wherein the controller is coupled to the permanent magnet motor and configured to control rotation of a rotor of the permanent magnet motor.

15. The PDU of claim 10 further comprising an optional encoder configured to detect an angular position of the cam shaft relative to the conveyor plane.

16. A method for controlling operation of a power drive unit (PDU) of an aircraft, comprising
receiving, by a controller, a request for the PDU to be in a raised position or in a lowered position;
detecting, by a rotary encoder, an angular position of a rotor of a permanent magnet motor of the PDU relative to a stator of the permanent magnet motor;
determining, by the controller, a current angular position of the PDU relative to a conveyor plane based on the detected current angular position of the rotor relative to the stator; and
controlling, by the controller, the permanent magnet motor such that the PDU is in the raised position or the lowered position based on the determined current angular position of the PDU.

17. The method of claim 16 , wherein the permanent magnet motor is configured to generate a cogging torque sufficient to cause the PDU to remain in the raised position in response to power being removed from the permanent magnet motor.

Assignees

• Goodrich Corp

Inventors

• Roberts Aaron
• Harms Scott
• Stegmiller Wesley K
• Scheer Dustin P

Classifications

• F16H37/124

  for interconverting rotary motion and reciprocating motion · CPC title

• H02K7/116

  with gears · CPC title

• H02K1/27

  Rotor cores with permanent magnets · CPC title

• B64D2009/006

  Rollers or drives for pallets of freight containers, e.g. PDU · CPC title

• B65G13/065

  with displacement of the roller · CPC title