Abstract:
A power train apparatus and motor grader are described. The apparatus or motor grader includes a power source for providing rotational mechanical power. A first output interface of the power source is driven by the rotational mechanical power from the power source and rotates around a first axis A differential includes at least one output shaft rotating around a second axis offset from and parallel to the first axis. A first gear is included in the differential, the first gear rotating around the second axis and providing rotational mechanical power to the at least one output shaft of the differential. A second gear rotates around the first axis, the second gear receiving rotational mechanical power from the output interface to the power source and providing rotational mechanical power to the first gear.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     Not applicable. 
     STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE DISCLOSURE 
     This disclosure relates to power trains, including power trains for vehicles. 
     BACKGROUND OF THE DISCLOSURE 
     In various applications, and with respect to various vehicles, there may be considerable advantages to reducing the envelope required to house power train components. For example, in outfitting older vehicle bodies with updated power train systems, it may be useful to design the updated power train systems (or components thereof) to fit within existing power train envelopes of the older vehicles. In this way, for example, potentially costly redesign of aspects of the older vehicles (e.g., aspects of existing power train envelopes) may be avoided. 
     SUMMARY OF THE DISCLOSURE 
     A power train apparatus and motor grader including a power train are disclosed. 
     According to one aspect of the disclosure, the power train apparatus (or motor grader) includes a power source for providing rotational mechanical power. The power source includes a first output interface driven by the rotational power from the power source and rotating around a first axis. The apparatus (or motor grader) includes a differential with at least one output shaft rotating around a second axis that is offset from and parallel to the first axis. The differential includes a first gear rotating around the second axis and providing rotational mechanical power to the at least one output shaft of the differential. The apparatus (or motor grader) further includes a second gear rotating around the first axis, the second gear receiving rotational mechanical from the output interface and providing mechanical power to the first gear. 
     One or more of the following features may also be included in the disclosed power train apparatus (or motor grader). The power source, the differential and the first and the second gears may be included in a vehicle (such as a motor grader) having one or more sets of bogie wheels, which may receive rotational mechanical power from the at least one output shaft of the differential. A primary rotational axis of the power source may be oriented transversely to a primary front-to-back axis of the motor grader. The power source may include an electric machine. 
     The power train apparatus (or motor grader) may include a transmission having an input interface and a second output interface. The input interface may receive rotational mechanical power from the first output interface, and the second output interface may receive rotational mechanical power from the input interface in order to provide rotational mechanical power to the second gear. The second gear may be located between the transmission and the power source. A first shaft may transmit rotational mechanical power between the first output interface and the input interface. A second shaft, coaxial with the first shaft, may transmit rotational mechanical power between the second output interface and the second gear. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an example motor grader in which the disclosed power train apparatus may be implemented; 
         FIG. 2  is a schematic view of an implementation of the disclosed power train apparatus in the motor grader of  FIG. 1 ; 
         FIGS. 3A and 3B  are schematic views of gearing configurations that may be utilized in the disclosed power train apparatus; and 
         FIG. 4  is a schematic view of another implementation of the disclosed power train apparatus in the motor grader of  FIG. 1 . 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The following describes one or more example embodiments of the disclosed lubrication apparatus, as shown in the accompanying figures of the drawings described briefly above. Various modifications to the example embodiments may be contemplated by one of skill in the art. 
     As also noted above, it may be useful to provide for compact configurations for various power train components. This may be particularly useful, for example, in retrofitting existing vehicles (and vehicle platforms) with updated power train systems. For example, in replacing a traditional internal combustion engine with an electric drive system, it may be useful to provide for an electric drive system that fits within an existing power train envelope in the relevant vehicle. Among other benefits, the disclosed power train apparatus may address this issue by providing for relatively compact arrangement of power train components. For example, the disclosed apparatus may provide a power source and transmission oriented transverse to the front-to-back axis of a vehicle. In certain embodiments, such a configuration may allow for an alignment of power output shafts of the power source and transmission that is parallel to an alignment of output shafts of an associated differential. Various gearing and shaft arrangements may be utilized with respect to this parallel alignment. In certain embodiments, the power source may include an internal combustion engine. In certain embodiments, the power source may include an electrical machine, a hydrostatic machine, or another type of power source. 
     Referring now to  FIG. 1 , motor grader  10  is depicted, with a primary front-to-back axis extending from left to right. In various embodiments, the disclosed power train apparatus may be employed in motor grader  10 , as well as various other vehicle types. With respect to motor grader  10 , for example, it may be difficult to package all of the necessary (or desired) components of a more conventional power train into the existing power train envelope(s) of the grader, which may be represented schematically as power train  12 . This difficulty may be further complicated, in certain instances, by the use of bogie wheels  14  in grader  10  (or other vehicle types). In this regard, a transverse power train arrangement may be of some benefit to motor grader  10  (or other vehicle types), including in configurations utilizing bogie wheels (as in  FIG. 1 ). As used herein, “transverse” may generally refer to an orientation that is generally perpendicular to a reference axis. With respect to motor grader  10 , for example, a transverse transaxle (or other apparatus) may be configured to provide (and transmit) rotational power along axes that are generally perpendicular to the primary front-to-back axis of grader  10  (i.e., along axes that are generally perpendicular to the plane of  FIG. 1 ). 
     Referring also to  FIG. 2 , the disclosed power train apparatus is depicted as a transaxle assembly including a power source  20 , which may be an internal combustion (or other) engine, an electrical machine (e.g., as powered by a separate generator (not shown) attached to a separate internal combustion engine (not shown)), a hydrostatic machine (e.g., as powered by a separate pump (not shown) attached to a separate internal combustion engine). As depicted in  FIG. 2 , the various axes of rotation (e.g., the axis of rotation of the output of power source  20 , extending left-to-right in  FIG. 2 ) may be oriented transverse to the front-to-back axis of grader  10  (i.e., an axis extending left-to-right in  FIG. 1 ). 
     Power source  20  may provide rotational mechanical power to transmission  22 . For example, stub shaft  44  may engage with an output interface of power source  20  (e.g., splined connection  16 , or a bolted connection, an integrally formed shaft connection, and so on (not shown), at power source  20 ) and may extend to also engage with an input interface of transmission  22  (e.g., splined connection  18 , or a bolted connection, integrally formed shaft connection, and so on (not shown), at transmission  22 ), thereby allowing transfer of rotational power from power source  20  to transmission  22 . Transmission  22  may include any variety of arrangements and gearings, including range gear sets, speed gear sets, clutches and brakes of various types, various internal shafts, and so on. 
     Transmission  22  (or power source  20 , if transmission  22  is not utilized) may provide rotational power to parallel axis gear set  26 . For example, rotational power may be transmitted from transmission  22 , via shaft  24 , to gear  28  (e.g., a conventional spur gear). Gear  28  may be meshed with bull gear  30 , with each of gears  28  and  30  rotating around an axis that is parallel to the rotational axis of the other gear  30  or  28 . Bull gear  30  may be included in differential  32  (or another power train apparatus). 
     Differential  32  may include various other components, such as gearing  34  (e.g., various spider and side gears), and output shafts  36  and  38 . With respect to motor grader  10 , for example, output shafts  36  and  38  may provide drive power to bogie wheels  14 , on respective sides of grader  10 . 
     In certain embodiments, bull gear  30  may take the place of a traditional ring gear within differential  32  (e.g., a traditional spiral bevel ring gear) and gear  28  may take the place of a traditional pinion gear for transmission of power to differential  32  (e.g., a conventional spiral bevel pinion gear). For example, in a traditional transaxle (or other) assembly, an output shaft of a power source or transmission may be oriented at a right (or other) angle to one or more output shafts of a differential. A pinion gear (e.g., a spiral bevel gear) at the end of the output shaft of the power source or transmission may accordingly mesh at a right (or other) angle with a ring gear of the differential, in order to transform the rotation from the power source/transmission into a perpendicular (or otherwise re-oriented) rotation at the output of the differential. Use of a transverse transaxle assembly, such as that depicted in  FIG. 2 , may allow for transmission of rotational power from power source  20  to the wheels of grader  10  (via output shafts  36  and  38 ) without requiring a right-angle (or otherwise angled) gear set, such as in the traditional configuration described above. This may represent another significant advantage of the contemplated power train apparatus, as eliminating angled gear sets and/or beveled gears from a power train design may significantly reduce the cost of manufacturing the power train. 
     It will be understood, as also noted above, that a variety of input and output interfaces may be utilized in the contemplated power train apparatus (and related vehicles). For example, an output interface may include an interface such as a splined connection, bolted connection, or integrally formed component that allows transmission of rotational power from a source (e.g., power source  20  or transmission  22 ) to an associated shaft (e.g., shaft  24 ) or component (e.g., transmission  22  or gear  28 ). Likewise, an input interface may be an interface such as a splined connection, bolted connection, or integrally formed component that facilitates reception of rotational power at a particular component or assembly (e.g., transmission  22  or gear  28 ) from a particular source (e.g., power source  20  or transmission  22 ) or associated component (e.g., shaft  24 ). In certain embodiments, a shaft (e.g., shaft  24 ) or gear (e.g., gear  28 ), or some portion thereof (e.g., an integral splined interface) may itself be considered an input or output interface. For example, if gear  28  is directly connected to (or integrally formed with, and so on) a component of transmission  22 , gear  28  (or the component of transmission  22  to which it is connected) may be viewed as an output interface of transmission  22 . Likewise, in the case of direct connection between components (e.g., as depicted between power source  20  and transmission  22  in  FIG. 2 ), the final relevant force-transmitting component of the upstream component (e.g., power source  20 ) may be viewed as an output interface, and the initial relevant force-transmitting component of the downstream component (e.g., transmission  22 ) may be viewed as an input interface. 
     Referring also to  FIGS. 3A and 3B , parallel axis gear set  26  may be configured in a variety of ways (e.g., as gear set  26   a  or gear set  26   b ). In certain embodiments, gear  28  (e.g., configured as gear  28   a ) may mesh directly with gear  30  (e.g., configured as gear  30   a ) in order to transmit rotational power from power source  20  (and transmission  22 ) to differential  32 . In certain embodiments, gear  28  (e.g., configured as gear  28   b ) may transmit power to gear  30  (e.g., configured as gear  30   b ) via one or more interposed idler gears (e.g., idler gear  40 ). As depicted in  FIG. 3B , for example, such idler gear(s) may also rotate around an axis parallel to the axes of gears  28  and  30 . 
     Referring also to  FIG. 4 , in certain embodiments various components of the disclosed power train apparatus may be arranged in various ways. For example, gear  28  may be located between power source  20   a  and transmission  22   a , which may provide additional space savings (or other benefits) with respect to a desired power train envelope. As depicted in  FIG. 4 , for example, coaxial shafts  24   a  and  42  may allow transmission of power from power source  20   a  to transmission  22   a  and then from transmission  22   a  to gear  28 , which may be aligned coaxially between power source  20   a  and transmission  22   a . For example, power may be transmitted from power source  20   a  to transmission  22   a  via internal coaxial shaft  24   a . Power may then be transmitted from transmission  22   a  to gear  28  via external (hollow) coaxial shaft  42 . As also described above, in such a configuration various types of power sources (e.g., internal combustion engines, electrical machines, and so on) and various types of transmissions may be utilized. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. Explicitly referenced embodiments herein were chosen and described in order to best explain the principles of the disclosure and their practical application, and to enable others of ordinary skill in the art to understand the disclosure and recognize many alternatives, modifications, and variations on the described example(s). Accordingly, various embodiments and implementations other than those explicitly described are within the scope of the following claims.