Planet brake differential

This invention relates to the use of a planet gear system to brake and drive a vehicle.

A planet brake differential is described herein. The details of the invention are set forth below in connection with the detailed description of the embodiments.

FIG. 1 depicts a schematic of an exemplary vehicle comprising an embodiment of the present invention.

FIG. 2 depicts a perspective view of an embodiment of the present invention.

FIG. 3 depicts the perspective view as seen in FIG. 2 with several elements omitted for clarity.

FIG. 4 depicts a front-end view of an embodiment of the present invention in the brake position, as more fully described below.

FIG. 5 depicts a front-end view of an embodiment of the present invention in the neutral position, as more fully described below.

FIG. 6 depicts a front-end view of an embodiment of the present invention in the drive position, as more fully described below.

FIG. 1 depicts a schematic of an exemplary vehicle 10 comprising an embodiment of the present invention. Vehicle 10 has a frame 11 on which planet brake differential 12 is mounted. As the configuration of vehicle 10 is well known in the art, it will only generally be described herein. Prime mover 13 is mounted on frame 11 and drives hydraulic pump 14 which is hydraulically connected to and drives hydraulic motor 15 . Motor 15 is in turn drivingly engaged to planet brake differential 12 . Planet brake differential 12 is drivingly engaged to wheels 16 through a pair of axles 25 . Control handles 17 are also mounted to frame 11 . It will be understood by one in the art that FIG. 1 depicts a schematic of an exemplary embodiment rather than a limiting one. Planet brake differential 12 has many applications and is not limited to applications such as vehicle 10 , nor is it limited to use with vehicles, as there are industrial applications for such units. Neither is planet brake differential 12 limited to applications in hydraulic or hydrostatic devices as other drive systems may be used, such as one using a clutch to select a gear or a variable speed transmission (“VST”).

FIG. 2 depicts a perspective view of an exemplary embodiment of the present invention. As shown in FIG. 2 , and in more detail in FIGS. 3–6 , the depicted embodiment of the present invention involves two brake-clutch assemblies 20 and 22 . For convenience, only the elements of assembly 22 are described herein in detail. It will be appreciated by those in the art that the same descriptions will apply to the corresponding elements in assembly 20 . It will likewise be understood that the embodiment depicted in FIG. 2 is merely exemplary and is not meant to be limiting. By way of example, axle 25 , as set forth in detail below, may be engaged at each end to a separate output device, such as wheels 16 , in which case assembly 20 would not be needed.

Ring gear 30 is located within and rotatable with respect to differential housing 35 . As shown more clearly in FIG. 3 , ring gear 30 has an input gear form 32 and support structures 34 extending from either side of input gear form 32 . Ring gear 30 is supported by housing 35 at support structures 34 . It will be appreciated that this is an exemplary embodiment, and ring gear 30 may be supported by other known means.

Axle 25 , which has a first end 26 , a second end 27 and a splined segment 28 therebetween, is located within and rotatable with respect to housing 35 . Axle 25 extends through housing 35 , and is drivingly engaged at first end 26 to an output device, such as wheels 16 or any other known output device. Axle 25 may be retained in housing 35 by a variety of techniques. For example, one or more washers may be positioned between the shoulder of spline 28 and an interior portion of housing 35 . Alternatively, a snap ring may be used to locate and retain axle 25 within housing 35 . As there are a number of retention methods, and those methods are unrelated to the present invention, they are not detailed herein.

Brake-clutch assembly 22 is disposed about axle 25 within housing 35 . Brake-clutch assembly 22 comprises drive plate 50 , brake plate 52 , engagement assembly 54 , which is located proximate to drive plate 50 and brake plate 52 , and planetary gear arrangement 42 , which is disposed about second end 27 of axle 25 .

Planetary gear arrangements are generally well known in the art, and will only briefly be described herein. For a more detailed description of a known planetary gear design, see commonly assigned U.S. Pat. No. 5,782,717, which is incorporated herein by reference. As shown most clearly in FIGS. 1 and 3 , planetary gear arrangement 42 comprises sun gear 43 and a plurality of planet gears 44 symmetrically disposed about sun gear 43 . Planet gears 44 are mated to and driven by interior gear form 31 of ring gear 30 . Four planet gears 44 are shown in the embodiment depicted in FIG. 3 , but any number of planet gears may be utilized so long as the number and arrangement of such gears is sufficient to meet the loading requirements of brake-clutch assembly 22 . Gear arrangement 42 also comprises a spur gear 45 , which is engaged to sun gear 43 . In the embodiment depicted, spur gear 45 and sun gear 43 are formed as a unitary component, as both gears are formed on opposite ends of sleeve 41 . Other constructions may be used within the spirit of this invention.

Each planet gear 44 is rotatably mounted on a corresponding pin 46 extending from planet gear carrier 47 . Planet gear carrier 47 is splined to and supported by axle 25 , such that planet gear carrier 47 and axle 25 rotate at the same rate.

Drive plate 50 is mounted on and driven by spur gear 45 and drive plate 50 is axially slidable with respect to spur gear 45 .

Brake plate 52 is mounted on and driven by splined portion 28 of axle 25 so that brake plate 52 is axially slidable with respect to splined portion 28 .

Engagement assembly 54 is disposed about drive plate 50 and brake plate 52 . In the depicted embodiment, engagement assembly 54 comprises engagement block 55 , slider block 58 and control arm 60 . Engagement block 55 is mounted to housing 35 through fasteners (not shown) and has a top side 56 and two side walls 57 extending therefrom, and at least one rail 59 positioned between the two side walls 57 . Engagement block 55 is positioned such that portions of drive plate 50 and brake plate 52 are disposed between respective interior portions of side walls 57 and a portion of slider block 58 . Slider block 58 is disposed on rail 59 and is slidable between any one of three positions; neutral, drive and brake. Each of the three positions will be described in more detail below.

Control arm 60 comprises handle member 61 integrally formed with shaft 62 , and shaft 62 extends through top side 56 of engagement assembly 54 to engage slider block 58 . Handle member 61 of control arm 60 may be coupled with control handle 17 through a known means, such as a cable. Therefore, the position of slider block 58 may be actuated by manipulating the corresponding control handle 17 . The engagement of shaft 62 with slider block 58 is by way of a cam (not shown) formed on the end of shaft 62 that engages slider block 58 . As cams and cable connections are known in the art, the details of these items are not shown.

Ring gear 30 is driven by gear train 23 , which is powered by motor output shaft 24 . As hydraulic motors are generally well known in the art, the details of motor 15 are not disclosed herein. For an example of a hydraulic motor, see commonly owned U.S. Pat. No. 5,201,692, which is incorporated herein by reference. As ring gear 30 rotates, it will drive each of planet gears 44 . When slider block 58 is in the neutral position, the resistance of the axle shaft to movement by contact with the ground causes rotation of gear 30 to be freely communicated through planets 44 into sun gear 43 , which freely rotates with respect to axle shaft 25 and housing 35 .

When slider block 58 is not engaged with either drive plate 50 or brake plate 52 , it is in the neutral position, as depicted in FIG. 5 . In this position, both drive plate 50 and brake plate 52 are free to rotate with respect to housing 35 . Moving slider block 58 from the neutral position toward drive plate 50 moves slider block 58 into the drive position, as depicted in FIG. 6 . In the drive position, frictional forces acting between engagement block 55 and slider block 58 will prevent rotation of drive plate 50 . Because drive plate 50 is splined to spur gear 45 , spur gear 45 , which is connected to sun gear 43 , will likewise be prevented from rotating with respect to housing 35 . With slider block 58 in the drive position, ring gear 30 will drive each of planet gears 44 . Because sun gear 43 is not free to rotate, planet gears 44 will now be forced to rotate about stationary sun gear 43 . The rotation of planet gears 44 about stationary sun gear 43 will in turn cause planet gear carrier 47 to rotate, thereby driving axle 25 .

Moving slider block 58 from the drive position toward brake plate 52 moves slider block into the brake position as depicted in FIG. 4 . When slider block 58 is in the brake position, frictional forces acting between engagement block 55 and slider block 58 will prevent brake plate 52 from rotating with respect to housing 35 . Because brake plate 52 and planet gear carrier 47 rotate at the same rate, due to both being splined to axle 25 , planet gear carrier 47 will not be able to rotate with respect to housing 35 . Because of this, with rotation of gear 30 planet gears 44 will rotate in place, driving sun gear 43 about stationary axle shaft 25 .

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed herein are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalents thereof.