Power transfer assembly with planetary gearset having carrier with crack arresting features

Patent metadata

Field	Value
Publication number	US-10851886-B2
Application number	US-201916548283-A
Country	US
Kind code	B2
Filing date	Aug 22, 2019
Priority date	Aug 24, 2018
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A two-speed transfer case for a four-wheel drive vehicle is provided. The transfer case has a two-speed planetary gearset, a range clutch, and a range shift mechanism. The planetary gearset includes a carrier unit having at least one crack arresting feature configured to limit propagation of a stress crack. The carrier unit includes a plurality of mounting holes for securing planet gears for rotation relative to the carrier unit. The gearset includes a sun gear configured for and a ring gear, with the planet gears in meshed engagement with the sun gear and the ring gear. The crack arresting feature extends at least partially through a portion of the carrier unit and is configured to receive a crack propagating from a central aperture of the carrier unit. The crack arresting feature is disposed radially between the central aperture and the mounting holes.

First claim

What is claimed is:

1. A planetary gearset comprising:
a sun gear;
a ring gear;
a carrier unit;
a planet gear rotatably supported by said carrier unit and in meshed engagement with said sun gear and said ring gear,
wherein said carrier unit is formed to include at least one crack arresting feature configured to inhibit propagation of a stress crack.

2. The planetary gearset of claim 1 , wherein the carrier unit includes clutch teeth adapted to be selectively engaged with a clutch, wherein said at least one crack arresting feature is located in proximity to said clutch teeth to inhibit propagation of the stress crack originating at one of said clutch teeth.

3. The planetary gearset of claim 2 , wherein said crack arresting feature includes a plurality of crack mitigating apertures formed in said carrier unit adjacent to said clutch teeth.

4. The planetary gearset of claim 3 , wherein said apertures are aligned along a common diameter and are circumferentially-oriented with respect to said clutch teeth.

5. The planetary gearset of claim 4 , wherein said apertures are throughbores.

6. The planetary gearset of claim 4 , wherein said apertures are partial depth bores.

7. The planetary gearset of claim 4 , wherein said apertures are lobe-shaped.

8. The planetary gearset of claim 4 , wherein said apertures are arc-shaped.

9. The planter gearset of claim 8 , wherein said apertures include a radially inner end and a radially outer end and define a curvature therebetween.

10. The planetary gearset of claim 2 , wherein said crack arresting feature includes a plurality of first crack mitigating apertures and a plurality of second crack mitigating apertures, wherein said first and second apertures are formed in said carrier unit adjacent to said teeth, and wherein said first apertures are aligned along a first diameter and said second apertures are aligned along a second diameter.

11. The planetary gearset of claim 10 , wherein said first apertures are staggered with respect to said second apertures.

12. The planetary gearset of claim 3 , wherein said carrier unit is a powdered metal component, and wherein said crack arresting feature is a crack mitigating aperture formed in the carrier unit during powdered metal fabrication.

13. The planetary gearset of claim 1 , wherein said carrier unit includes a central aperture, and wherein said crack arresting feature is oriented in proximity to said central aperture, wherein said feature includes a plurality of crack mitigating bores surrounding said central aperture.

14. A transfer case for a vehicle, the transfer case comprising:
a rotary input shaft operational at a first speed;
a rotary output shaft;
a sun gear configured for concurrent rotation with the rotary input shaft;
a ring gear;
a carrier unit;
a planet gear rotatably supported by said carrier unit and in meshed engagement with said sun gear and said ring gear;
a range mechanism configured to shift between meshed engagement with the rotary input shaft to drive the rotary output shaft at the first speed and meshed engagement with the carrier unit to drive the rotary output shaft at a second speed;
wherein said carrier unit is formed to include at least one crack arresting feature configured to inhibit propagation of a stress crack.

15. The transfer case of claim 14 , wherein the crack arresting feature comprises a plurality of apertures extending at least partially through a carrier ring of the carrier unit, wherein the carrier ring includes a plurality of teeth configured for meshed engagement with the range mechanism and a plurality of mounting holes for supporting the planet gears for rotation, wherein the plurality of apertures are disposed radially between the plurality of teeth and the mounting holes.

16. The transfer case of claim 15 , wherein all of the plurality of apertures are arranged at approximately the same diameter from a diametrical center of the carrier unit.

17. The transfer case of claim 15 , wherein the plurality of apertures are arranged at different diameters from a diametrical center of the carrier unit.

18. The transfer case of claim 15 , wherein the apertures have an arc shape with a radially inner end and radially outer end, wherein the arc shape is concave in a radially outer direction.

19. The transfer case of claim 18 , wherein the number of apertures corresponds to the number of mounting holes.

20. The transfer case of claim 19 , wherein the apertures are disposed along a load path extending between the teeth and the mounting holes to intercept a crack originating at the teeth and propagating toward the mounting holes.

Assignees

• Magna Powertrain America Inc

Inventors

• Bujold Michael
• Larson Ralph

Classifications

• F16H2200/2005

  with one sets of orbital gears · CPC title

• B60Y2400/421

  Dog type clutches or brakes · CPC title

• F16H2200/0034

  the gear ratios comprising two forward speeds · CPC title

• F16H1/28

  with gears having orbital motion · CPC title

• B60K2023/0825

  for adding torque to the front wheels · CPC title