Shaft support for a drive device

A drive device having a shaft support structure located within its housing, such as an axle support structure for providing additional support to a pair of output axles under load. The axle support structure comprises at least one aperture sized to receive a bushing that may have a non-rotation feature. The housing may also include a shaft support structure for other shafts, such as a jackshaft of a gear reduction system disposed between a transmission and the driven output axles.

BACKGROUND OF THE INVENTION

This application is related to drive devices for a variety of vehicles, including walk-behind vehicles such as snow throwers, including support structure for axles and other shafts. Depending on the vehicle application, axle loading in these drive devices can be severe. There exists opportunities for improvement to the housings of drive devices to accommodate such axle loading and to provide support for other shafts.

SUMMARY OF THE INVENTION

The present invention provides an improved shaft support in a housing for a drive device, which may be used in a variety of vehicle or other applications to support axles and other shafts such as a jackshaft. The term jackshaft is used herein to generically refer to an intermediate support shaft, such as a shaft to support gears in a gear reduction system.

A better understanding of the properties of the invention will be obtained from the following detailed description and accompanying drawings which set forth one or more illustrative embodiments and are indicative of the various ways in which the invention may be employed.

DETAILED DESCRIPTION OF THE DRAWINGS

It should be noted that in the description and drawings, like or substantially similar elements may be labeled with the same reference numerals. However, sometimes these elements may be labeled with differing or serial numbers, such as, for example, in cases where such labeling facilitates a more clear description. Additionally, the drawings set forth herein are not necessarily drawn to scale, and in some instances proportions may have been exaggerated to more clearly depict certain features. Such labeling and drawing practices do not necessarily implicate an underlying substantive purpose. As stated above, the present specification is intended to be taken as a whole and interpreted in accordance with the principles of the present invention as taught herein and understood by one of ordinary skill in the art.

The embodiments of the drive devices disclosed herein may be used in a variety of vehicles such as a walk-behind snow thrower or other such vehicles. However, the embodiments disclosed herein are not limited to use in this type of vehicle. The transmission disclosed herein is similar in many respects to that shown in U.S. Pat. No. 8,464,610, the terms of which are incorporated herein by reference in their entirety.

Exemplary drive devices16and616are depicted in detail inFIGS. 1-8 and 9-14, respectively. Drive devices16and616are shown as a type of continuously variable hydraulic or hydrostatic transmission of a type known as an integrated hydrostatic transmission. Such transmissions are well known in the art and will only generally be described herein. Moreover, it will be appreciated by those in the art that the scope of the present invention is not limited to hydraulic transmissions, but may include any type of continuously variable transmission, all of which are referred to generically as a transmission herein. Certain aspects of drive device16are described in detail, with the understanding that operation of drive device616will be substantially the same except as noted.

Drive device16is powered by a prime mover (not shown) that, in the depicted embodiment, drives input shaft34by way of a belt and pulley system. For convenience, only pulley32of the belt and pulley system is shown. Input shaft34is engaged to and drives hydraulic pump36, which is rotatably disposed on pump running surface163of center section38. Motor40is rotatably disposed on motor running surface164, formed on motor mounting portion174. Hydraulic pump36is hydraulically connected to motor40through internal porting165, which is formed in center section38and connects pump running surface163, formed on pump mounting portion175, with motor running surface164.

Center section38may have a plurality of other components installed therein or thereon to aid in the operation of drive device16. Other elements located on or in center section38may include filter44and fasteners50. As seen, for example, inFIG. 3, fasteners50extend parallel to input shaft34and output shaft48to support center section38in a sump such as sump620formed by first housing652and second housing654inFIGS. 9 and 10.

A swash plate such as swash plate56is provided to control the displacement of hydraulic pump36. Thus, as swash plate56is moved by trunnion arm58, the displacement of pump pistons35in hydraulic pump36changes, causing fluid to flow through the internal porting165of center section38to motor40, causing motor40to rotate. Trunnion arm58may be moved manually by a control arm59or by an electronic or hydraulic control, as is known in the art. Examples of electronic controls that could be used in connection with the present invention may be found in U.S. Pat. Nos. 7,073,330 and 8,844,658, both of which are commonly owned with this invention and incorporated herein by reference in their entireties.

Motor40drives output shaft48, which has a pinion bevel gear60mounted thereon. Output shaft48passes through and is supported by opening144in center section38. The end of output shaft48opposite pinion gear60is supported by housing52and may include a thrust washer or disc (not shown) installed in shaft support53of housing52to prevent excessive wear to housing52. Pinion gear60may rotate on wear washer65to prevent excessive wear to center section38.

As output shaft48rotates, pinion gear60drives clutch gear62. Located on either side of clutch gear62are rings86, which are part of clutch assembly61, the operation of which is described in detail below. As a preliminary matter, both rings86are biased by springs80to the engaged position, and an arm72, in conjunction with a fork106, is positioned proximate to each ring86, and may rotate to move rings86to the disengaged position, independent of one another. Each ring86is associated with one of shafts68or70through a separate gear train. By allowing for individual engagement and disengagement of the rings86, individual control of shafts68and70may be provided, allowing drive device16to both steer and propel a vehicle comprising drive device16.

Steering of a vehicle is accomplished by use of clutch assembly61, which is shown in detail in the previously incorporated U.S. Pat. No. 8,464,610. InFIGS. 4 and 5, both rings86of clutch assembly61are shown in the engaged position. In this position, clutch gear62provides motive power to rotate both flange gears90. Each flange gear90is, in turn, engaged to a reduction gear set100. In the depicted embodiment, each reduction gear set100includes a reduction spur gear101and a spur gear104. Each spur gear104is connected to one of axle shaft68or70by splines110.

Jackshaft102supports the pair of reduction spur gears101. Cupped washers103are used near each end of jackshaft102to prevent the hubs of gears101from cutting into housing54. Jackshaft102is retained by plugs57installed in each side of housing54.

Pump input shaft34, motor output shaft48and clutch actuator arms72are all partially supported by center section38. Opening146supports one end of input shaft34, while opening144supports one end of output shaft48. Openings142support ends143of arms72which, in turn, support actuator forks106. Clutch assembly61is entirely supported on shaft67which is installed through openings140in clutch support arms161of center section38.

In order to provide a strong and rigid center section, a diamond-shaped mounting pattern is utilized in conjunction with a diamond-shaped reinforcement rib pattern. Four fasteners50are inserted through openings148to secure center section38to housing52, providing a rigid subassembly of these components. A central strengthening rib162and four additional ribs166form a double triangular pattern within an overall diamond pattern. Specifically, as seen inFIG. 11, two ribs166extend from proximate an opening148to motor mounting portion174, and two ribs166extend from proximate an opening148to pump mounting portion175. Fluid passage structures167and168, in combination with central rib162and buttressing ribs176and178, form a sturdy H-shaped central structure to further strengthen, stiffen, and help maintain flatness of center section38.

Easily accessible valve openings154are provided for installation of valves42in center section38. Filter44is easily installed over valves42. Central strengthening rib162forms one side of pockets150so that minimal material is used to form pockets150. Installation of valves170in pockets150is also very simple.

A hydraulic drive device616having a modified housing comprising a first housing652and a second housing654is disclosed inFIGS. 9-14. As noted, hydraulic drive device616is substantially similar to hydraulic drive device16, and its second housing654comprises many features that are substantially similar to those of housing54. Features which are substantially similar or identical to those previously described, e.g. engagement structure613, will not be detailed herein.

Second housing654includes an axle support structure655centrally located within second housing654to receive the inner journals668b,670bof the collinear axles668,670. In wheeled vehicle applications or other applications employing relatively large axle loads, the axles668,670may require an additional axle support structure655within second housing654to prevent unwanted flexion and/or radial or axial movement of the axles668,670. Such movement can affect not only the integrity of axles668,670, but also the alignment of the axle-driving spur gears604relative to corresponding elements of reduction gear set600, increasing wear and reducing their useful life. Thus, axle support structure655provides increased strength and rigidity to the drive train. It should be noted that depending upon the anticipated loading of the axles668,670, hydraulic drive device616may be used in applications with or without axle support housings (e.g. as shown without inFIG. 9). The required length of the axles668,670and the presence or absence of additional bearings external to second housing654(e.g. a bearing associated with a vehicle frame or a pillow block bearing) will affect that determination.

As best shown inFIGS. 10-14, a sump620is formed by first housing652and second housing654. Second housing654comprises two generally parallel sides or side walls654bthrough which axles668and670extend. These side walls654bare joined by a third side, or rear wall,654cthat is generally perpendicular thereto. Axle support structure655is fixedly attached to second housing654. In the disclosed embodiment, axle support structure655is formed integral to second housing654and extends from rear wall654cin a direction generally parallel to the side walls654band also generally parallel to the rotational axes of pump input shaft634and motor output shaft648. The support may alternatively be formed from a separate piece of material and attached to second housing654with fasteners such as bolts, machine screws, rivets, or the like, or attached by means of adhesives, welding, or other joining methods known in the art.

The axle support structure655is depicted as having a pair of bosses655acontaining a plurality of collinear, bushing support apertures655b. The bushing support apertures655bare sized to accept one or more bushings. The bushing support apertures655bmay be alternatively configured as journal bearings or adapted to receive one or more bearings, such as needle or ball bearings, depending upon the desired performance and load carrying characteristics. Axle support structure655could likewise incorporate only a single boss similar to boss655aand a single bushing support aperture.

In the embodiment depicted herein, a single bushing681having a first end681xand a second end681yis inserted through the bushing support apertures655b. The first end681xof bushing681comprises a bushing flange681d. The bushing flange681dserves as a stop to limit the depth of insertion of bushing681into the bushing support apertures655b. The bushing flange681dfurther comprises a plurality of anti-rotation features or, as illustrated by way of example only, slots681a. A single anti-rotation slot681aengages a support rib655cof the axle support structure655and prevents unwanted rotation of bushing681within the axle support structure655. The use of the two anti-rotation slots681adepicted speeds assembly. It should be noted that the anti-rotation feature, whether a slot or some other suitable shape, could be formed on the support rib655cto retain a corresponding feature on the bushing flange681d. After insertion and location, bushing681is retained in axle support structure655by insertion of a retaining ring683into an annular retaining ring groove681cformed on the second end681yof bushing681. With reference toFIG. 13, bushing681may be inserted into axle support structure655from the left or right side as support rib655cextends from both the left and right sides of axle support structure655. Alternatively (not shown), the first end681xand second end681yof bushing681may have substantially similar forms, with each end formed with a retaining ring groove for retention by a retaining ring.

The bore681bof bushing681is sized to accept the inner journals668b,670bof the axles668,670. The bushing681, in conjunction with axle support structure655, provides additional support for the axles and provides a suitable surface for rotation of the axles668,670within second housing654. The outer journals668a,670aof axles668,670, respectively, are rotationally supported by second housing apertures654a. Alternatively (not shown), second housing apertures654acan be sized to accommodate bearings, such as ball bearings, depending upon the desired performance and load carrying characteristics. Axles668,670, via splines668c,670c, engage the corresponding splines610of final spur gears604, and are thus driven by reduction gear set600.

As compared to the reduction gear set100of hydraulic drive device16, reduction gear set600has been modified to accommodate axle support structure655. As shown inFIGS. 10 and 14, the final spur gears604have been spaced apart and reduced in width to eliminate interference with axle support structure655. In addition, lightening features604ahave been added to the final spur gears604to reduce material use. Other modifications to reduction gear set600include the addition of a spacer624on jackshaft602to separate the reduction spur gears or combination gears601, whose width is also reduced. The function of both the dual clutch assembly661and reduction gear set600is substantially identical to that of dual clutch assembly61and reduction gear set100and will not further be described herein. As with the prior embodiments, clutch support shaft667is supported on center section638, and jackshaft602is supported by second housing654. Center section638is similar in many respects to center section38, with minor modifications not material to the present invention.

In a further embodiment, as depicted inFIGS. 15 and 16, an additional support structure is disclosed for supporting the jackshaft702used to support reduction spur gears701, in addition to supporting the axle shafts768and770as in prior embodiments. Reduction spur gears701are combination gears engaged to final spur gears704to drive axles768and770. As shown most clearly inFIG. 16, internal wall754cof second housing754has a unitary support structure755formed thereon.

Unitary support structure755has two lobes755a, each having an aperture755bto provide support for bushing781, and lobes755aare connected by a bridge structure755d. A pair of structural support ribs755cis also extended outwardly from each lobe755a. Bushing781is similar to previously described bushing681and comprises anti-rotation slots781athat are similar to anti-rotation slots681a. A retaining ring783secures bushing781in position to ensure proper engagement of an anti-rotation slot781awith a rib755c. To provide proper spacing of the gears, a pair of gear spacers786is provided. A spacer786is disposed between each spur gear704and its respective side wall754b. A pair of washers785and retaining rings784are also used to provide wear surfaces and properly locate spur gears704. Retaining rings784engage axles768and770to secure them in second housing754.

Jackshaft support rib755eextends from bridge755dand has aperture755fformed therein to support jackshaft702. A pair of spacers724is disposed one on either side of support rib755e. Each spacer724is disposed between the support rib755eand one of the combination reduction spur gears701. It will be noted that the use of the two spacers724may accommodate the use of narrower reduction spur gears701than in the prior embodiment. Thus, a simple means for supporting the jackshaft702is provided. While the two support structures disclosed herein are depicted as a unitary structure, it will be understood that these two supports could also be separate structures, and support structure755or the separate structures could also be fastened to the wall as discussed above, as opposed to being integrally formed therewith. It should also be understood that jackshaft702may be allowed to rotate and that aperture755fcan be adapted to further support a bushing, a journal bearing or other type of bearing, such as a needle bearing or a ball bearing, to support a rotating jackshaft702, depending upon desired performance and load carrying characteristics.