Multi-step range cam for two-speed transfer case

Patent metadata

Field	Value
Publication number	US-10464415-B2
Application number	US-201715823670-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Nov 29, 2016
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

A two-speed transfer case for a four-wheel drive vehicle is provided. The transfer case has a two-speed gear reduction unit, a range clutch, and a range shift mechanism. The range shift mechanism is operably disposed between an input shaft and a rear output shaft and includes a range cam defining a guide slot having a unique profile for converting rotation thereof into linear movement of the range clutch. The guide slot includes low-range dwell segment and a high-range dwell segment interconnected by a range shift segment. The range shift segment defines a plurality of interconnected cam portions, wherein each cam portion is associated with a different load required to move the range clutch between a high-range and low-range position. The transfer case further includes a mode shift mechanism for establishing a high-range drive connection and a low-range drive connection associated with the dwells of the range cam.

First claim

What is claimed is:

1. A two-speed transfer case for a four-wheel drive vehicle having a powertrain and front and rear drivelines, the two-speed transfer case comprising:
an input shaft adapted to be driven by the powertrain;
a rear output shaft adapted to be coupled to the rear driveline;
a front output shaft adapted to be coupled to the front driveline;
a gear reduction unit having an input component driven by said input shaft and an output component driven at a reduced speed relative to said input component;
a range clutch rotationally fixed to said rear output shaft and movable between a first range position whereat said range clutch is drivingly connected to said input component for establishing a high-range driving position, a second range position whereat said range clutch is drivingly connected to said output component for establishing a low-range driving position; and
a range shift mechanism including a range fork coupled to the range clutch and having a follower, a range cam defining a guide slot within which said follower is disposed, said guide slot having a high-range dwell segment associated with locating said range clutch in said first range position, a low-range dwell segment associated with locating said range clutch in said second range position, and a range shift segment interconnecting said dwell segments; and
wherein said range shift segment defines a plurality of cam portions extending at distinct slopes relative to said dwell segments, each of said slopes associated with a different load requirement for moving said range clutch between said high-range and said low-range positions.

2. The two-speed transfer case according to claim 1 wherein said plurality of cam portions includes three distinct cam portions each extending at one of said distinct slopes.

3. The two-speed transfer case according to claim 1 wherein said cam portions extend at distinct lengths.

4. The two-speed transfer case according to claim 1 further comprising a range actuator for controlling rotation of said range cam for moving said range clutch between said high-range position and said low-range position.

5. The two-speed transfer case according to claim 1 wherein said follower is disposed in said guide slot such that rotational movement of said range cam moves said range fork axially for moving said range clutch between said first and second range positions relative to said gear reduction unit.

6. A two-speed transfer case for a four-wheel drive vehicle having a powertrain and front and rear drivelines, the two-speed transfer case comprising:
an input shaft adapted to be driven by the powertrain;
a rear output shaft adapted to be coupled to the rear driveline;
a front output shaft adapted to be coupled to the front driveline;
a gear reduction unit having an input component driven by said input shaft and an output component driven at a reduced speed relative to said input component;
a range mechanism including a range clutch operable in a first range position to drivingly connect said rear output shaft for rotation with said output component to establish a high-range drive connection, and further operable in a second range position to drivingly connect said rear output shaft for rotation with said input component to establish a low-range drive connection;
a transfer mechanism driven by one of said front and rear output shafts;
a mode mechanism including a mode clutch operable in a first mode position to disconnect said transfer mechanism from the other one of said front and rear output shafts to establish a two-wheel drive mode, and further operable in a second mode position to connect said transfer mechanism to the other one of said front and rear output shafts to establish a four-wheel drive mode;
a range shift mechanism having a range fork connected to said range clutch and a rotary-to-linear conversion device operable to convert an input torque into a shift force used for moving said range clutch via said range fork between its first and second range positions; and
a mode shift mechanism operable for moving said mode clutch between its first and second mode positions;
wherein said rotary-to-linear conversion device includes a guide slot defining a first dwell segment, a second dwell segment, and a range shift segment interconnecting said first and second dwell segments, wherein a range follower coupled to said range fork is disposed within said guide slot, and wherein said range shift segment of said guide slot is defined by a plurality of at least two distinct cam portions each having a different camming profile selected to generate different shift forces in response to the same input torque.

7. The two-speed transfer case according to claim 6 wherein said rotary-to-linear conversion device is a rotary cam, and wherein said guide slot formed in said rotary cam includes three distinct cam portions.

8. A two-speed transfer case for a four-wheel drive vehicle having a powertrain and front and rear drivelines, the two-speed transfer case comprising:
an input shaft adapted to be driven by the powertrain;
a rear output shaft adapted to be coupled to the rear driveline;
a front output shaft adapted to be coupled to the front driveline;
a gear reduction unit having an input component driven by said input shaft and an output component driven at a reduced speed relative to said input component;
a range clutch rotationally fixed to said rear output shaft and movable between a first range position whereat said range clutch is drivingly connected to said input component for establishing a high-range driving position, a second range position whereat said range clutch is drivingly connected to said output component for establishing a low-range driving position; and
a range shift mechanism including a range fork coupled to said range clutch, a rotary-to-linear conversion device defining a guide slot within which said range fork is in communication with, said guide slot having a high-range dwell segment associated with locating said range clutch in said first range position, a low-range dwell segment associated with locating said range clutch in said second range position, and a range shift segment having a profile defining at least two load requirements interconnecting said dwell segments.

9. The two-speed transfer case according to claim 8 wherein said range shift segment includes three distinctly sloped cam portions including a first cam portion interconnected to said high-dwell segment, a second cam portion interconnected to said low-dwell segment and a third cam portion interconnecting said first and second cam portions.

10. The two-speed transfer case according to claim 8 wherein range shift mechanism further includes a shift rail and said range fork is slideably coupled thereto and said rotary-to-linear conversion device includes a sector plate.

11. The two-speed transfer case according to claim 10 wherein said range fork includes a hub segment having a range pin extending in said guide slot such that rotation of said sector plate causes linear movement of range fork due to said range pin moving within said range guide slot.

12. The two-speed transfer case according to claim 11 wherein said range clutch includes a range collar having external clutch teeth and internal clutch teeth and being axially moveable along said rear output shaft between said first and second range positions.

13. The two-speed transfer case according to claim 12 wherein said range collar establishes a high-range position wherein said internal clutch teeth engage said output shaft, a low-range position wherein said external teeth engage said input component of said gear red

Assignees

• Magna Powertrain America Inc

Inventors

• Sharma Anupam
• Jarzyna Pete
• Harmon Dan
• Drill Daniel M

Classifications

• B60K23/0808

  for varying torque distribution between driven axles, e.g. by transfer clutch · CPC title

• B60K17/3467 Primary

  combined with a change speed gearing, e.g. range gear · CPC title