Clutched driven device and associated clutch mechanism

Patent metadata

Field	Value
Publication number	US-9267552-B2
Application number	US-201214349423-A
Country	US
Kind code	B2
Filing date	Oct 1, 2012
Priority date	Oct 6, 2011
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

A driven accessory ( 10 ) is provided that includes a first rotary clutch portion ( 50 ), a second rotary clutch portion ( 52 ), a wrap spring ( 56 ) and an actuator ( 60 ). The wrap spring ( 56 ) is configured to transmit rotary power between the first and second rotary clutch portions ( 50, 52 ). The actuator ( 60 ) is selectively operable for generating a drag force that is applied to the wrap spring ( 56 ) to control torque transmission through the wrap spring ( 56 ). The actuator ( 60 ) includes an actuator input member ( 140 ), a brake shoe ( 144 ) and a motor ( 142 ) that is configured to translate the brake shoe ( 144 ) axially along the rotary axis ( 70 ). The drag force is generated when the motor ( 142 ) is operated in a first mode so that transmission of rotary power between the first rotary clutch portion ( 50 ) and the second rotary clutch portion ( 52 ) is interrupted.

First claim

What is claimed is:

1. A driven accessory comprising:
a first rotary clutch portion that is disposed about a rotary axis and adapted to receive a rotary input, the first rotary clutch portion defining a clutch surface;
a second rotary clutch portion that is disposed about the rotary axis and adapted to be coupled to an input shaft;
a wrap spring having a first end, a second end and a plurality of helical coils between the first end and the second end, the plurality of helical coils engaging the clutch surface, the wrap spring being configured to selectively transmit rotary power between the first rotary clutch portion and the second rotary clutch portion, the rotary power being received by the helical coils from the first rotary clutch portion and being transmitted through the first end; and
an actuator that is selectively operable for generating a drag force that is applied to the second end of the wrap spring, the actuator comprising an actuator input member and a brake shoe, the actuator input member being rotatable about the rotary axis relative to the first rotary clutch portion and having a brake rotor with a plurality of first teeth that are disposed circumferentially about the brake rotor, the brake shoe comprising a plurality of second teeth that are meshingly engaged to the first teeth of the brake rotor, the brake shoe being rotatable about and axially movable along the rotary axis.

2. The driven accessory of claim 1 , further comprising a motor that is configured to translate the brake shoe.

3. The driven accessory of claim 2 , wherein the motor is a linear motor.

4. The driven accessory of claim 3 , wherein the linear motor comprises a coil of wire and an armature.

5. The driven accessory of claim 4 , wherein the brake shoe is overmolded onto at least a portion of the armature.

6. The driven accessory of claim 4 , wherein the armature is formed of a plastic material having a ferromagnetic filler material.

7. The driven accessory of claim 4 , wherein the coil of wire is mounted on a bracket and wherein the armature is received within the coil of wire.

8. The driven accessory of claim 1 , wherein at least one rolling element is received between the first teeth and the second teeth.

9. The driven accessory of claim 8 , wherein the first teeth have first axial end faces, wherein the second teeth have second axial end faces and wherein the at least one rolling element abuts the first and second axial end faces.

10. The driven accessory of claim 9 , wherein the first and second axial end faces are tapered.

11. The driven accessory of claim 1 , wherein the first teeth and the second teeth have pressure angles that are less than 90 degrees.

12. A driven accessory comprising:
a first rotary clutch portion that is disposed about a rotary axis and adapted to receive a rotary input, the first rotary clutch portion defining a clutch surface;
a second rotary clutch portion that is disposed about the rotary axis and adapted to be coupled to an input shaft;
a wrap spring having a first end, a second end and a plurality of helical coils between the first end and the second end, the plurality of helical coils engaging the clutch surface, the wrap spring being configured to selectively transmit rotary power between the first rotary clutch portion and the second rotary clutch portion, the rotary power being received by the helical coils from the first rotary clutch portion and being transmitted through the first end; and
an actuator that is selectively operable for generating a drag force that is applied to the second end of the wrap spring, the actuator comprising an actuator input member, a brake shoe and a motor, the actuator input member being rotatable about the rotary axis relative to the first rotary clutch portion and having a brake rotor, the brake shoe being rotatable about and movable axially along the rotary axis, the motor being selectively operable to translate the brake shoe axially along the rotary axis, wherein the drag force is generated when the motor is operated in a first mode so that transmission of rotary power between the first rotary clutch portion and the second rotary clutch portion is interrupted, and wherein the drag force is not generated when the motor is operated in a second mode to permit transmission of rotary power between the first rotary clutch portion and the second rotary clutch portion.

13. The driven accessory of claim 12 , wherein the motor is a linear motor.

14. The driven accessory ( 10 ) of claim 13 , wherein the linear motor comprises a coil of wire ( 212 ) and an armature ( 202 ).

15. The driven accessory of claim 12 , wherein the actuator input member comprises a plurality of first teeth and the brake shoe comprises a plurality of second teeth that are meshingly engaged to the first teeth.

16. The driven accessory of claim 15 , wherein at least one rolling element is received between the first teeth and the second teeth.

17. A driven accessory comprising:
an accessory portion having a housing, an input shaft and a shaft bearing that supports the input shaft for rotation in the housing; a bracket coupled to the housing;
a first rotary clutch portion that is disposed about a rotary axis and adapted to receive a rotary input, the first rotary clutch portion defining a clutch surface;
a second rotary clutch portion that is disposed about the rotary axis and coupled to the input shaft;
a wrap spring having a first end, a second end and a plurality of helical coils between the first end and the second end, the plurality of helical coils engaging the clutch surface, the wrap spring being configured to selectively transmit rotary power between the first rotary clutch portion and the second rotary clutch portion, the rotary power being received by the helical coils from the first rotary clutch portion and being transmitted through the first end;
an actuator that is selectively operable for generating a drag force that is applied to the second end of the wrap spring, the actuator comprising an actuator input member and a brake shoe, the actuator input member being rotatable about the rotary axis relative to the first rotary clutch portion and having a brake rotor with a plurality of first teeth that are disposed circumferentially about the brake rotor, the brake shoe comprising a plurality of second teeth that are meshingly engaged to the first teeth (T 1 ) of the brake rotor, the brake shoe being rotatable about and axially movable along the rotary axis; and
a clutch bearing that supports the first rotary clutch portion for rotation relative to the bracket, the clutch bearing being received in the bracket.

18. The driven accessory of claim 17 , wherein the clutch bearing overlaps the shaft bearing in an axial direction along a rotational axis of the input shaft.

19. The driven accessory of claim 17 , wherein the first rotary clutch portion is coupled for rotation with a pulley sheave that is configured to engage an endless power transmitting element, wherein a centerline of the endless power transmitting element is disposed less than or equal to 15 mm of the axial center of the clutch bearing.

20. The driven accessory of claim 17 , further comprising a pulley sheave coupled to the first rotary clutch portion, the pulley sheave being configured to engage an endless power transmitting element, wherein the endless power transmitting element applies a hub load to the pulley sheave, and wherein no portion of the hub load is transmitted through the shaft bearing to the housing.

Assignees

• Litens Automotive Inc

Inventors

• Boyes Andrew M
• Ferlik Ivan

Classifications

• F01P5/12

  Pump-driving arrangements · CPC title

• F02B67/06

  driven by means of chains, belts, or like endless members · CPC title

• F16D13/12 Primary

  with an expansible band or coil co-operating with the inner surface of a drum or the like (F16D13/02 takes precedence; similar brakes F16D51/02) · CPC title

• F16D27/105

  with a helical band or equivalent member co-operating with a cylindrical coupling surface · CPC title

• F16D13/58 Primary

  Details {(tools for assembling or disassembling clutches B25B27/0064)} · CPC title