Abstract:
A drive arrangement includes a housing having two chambers and a partition defining an annular space within the housing. A disk is mounted on a shaft of the drive arrangement and includes an annular portion disposed within the annular space. A face of the annular portion is axially spaced from the partition by a gap clearance. An axial dimension of the gap clearance is such that rotation of the disk generates a negative pressure gradient for drawing fluid from the first chamber through the gap clearance in a radial direction toward the rotation axis. The fluid then moves along the face of the disk in a radial direction away from the rotation axis under centrifugal action of the rotating disk. The outer periphery of the disk is spaced from the housing to permit fluid to pass, by centrifugal action, from the outer periphery toward a second chamber.

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 a rotating fluid transport arrangement, which may be used in various assemblies (e.g., power transfer drives) to transport fluid from one area to another. 
     BACKGROUND OF THE DISCLOSURE 
     Various work vehicles are driven (e.g., by rotation of ground engaging wheels or tracks) using various drive arrangements (e.g., drive axles, final drives, etc.) that include driven components (e.g., brakes, clutches, gears and so on). Liquid lubricating and cooling fluid may be delivered to these components, or these components may be submerged in fluid. The drive arrangements may also include drive components (e.g., electric motors or hydraulic motors) mounted within the same housing as the driven components. The close proximity of the motor and gears, for example, may lead to fluid pooling or otherwise migrating from the driven components into the chamber housing the drive component. In the case of an electric motor, accumulation of fluid into the small gap between the rotor and stator may cause power inefficiencies resulting from the drag induced by the presence of the fluid, especially when the housing and fluid are pressurized. 
     SUMMARY OF THE DISCLOSURE 
     This disclosure provides a system for evacuating liquid such as a lubricating and cooling fluid from an internal chamber, such as a drive motor chamber, using a rotating member spinning in a controlled gap clearance to carry liquid away from the drive motor chamber. 
     In one aspect the disclosure provides a drive arrangement having a housing with first and second chambers. A shaft may be mounted within the housing for rotation about a rotation axis extending between the first and second chambers. A partition within the housing between the first and second chambers may allow fluid communication there between. A disk mounted to the shaft for co-rotation about the rotation axis may have an outer periphery and an annular portion with a face having entraining surface features to stimulate fluid transport of the rotating disk. The face of the disk is spaced apart from the partition by a gap clearance. The gap clearance may have an axial dimension (in an axial direction of the drive arrangement) selected such that rotation of the disk creates a negative pressure gradient, which draws fluid from the first chamber into the second chamber. Initially fluid may be drawn in the axial direction from the first chamber through a passage into the gap clearance. From there fluid is drawn in a radially inward direction toward the rotation axis until the centrifugal action of the rotating disk thereafter moves the fluid along the face of the disk in a radially outward direction away from the rotation axis. The outer periphery of the disk may be spaced from the housing to permit fluid to pass, by centrifugal action, from the outer periphery of the disk into the second chamber. 
     In another aspect the disclosure provides a drive arrangement having housing with first and second chambers. A shaft may be mounted within the housing for rotation about a rotation axis extending between the first and second chambers. An annular wall fixed within the housing and positioned axially with respect to the rotation axis between the first and second chambers may allow fluid communication between the first and second chambers. The annular wall may have an inner diameter between the first and second chambers radially inward of a passage extending between the first and second chambers. A disk mounted to the shaft for co-rotation about the rotation axis may have an outer periphery and an annular portion having a face with entraining surface features for stimulating fluid transport of the rotating disk. The face of the disk may be spaced along the rotation axis from the annular wall by a gap clearance. The gap clearance may have an axial dimension selected such that rotation of the disk creates a pressure gradient drawing fluid from a direction of the first chamber through the gap clearance in a radial direction toward the rotation axis to an inner diameter of the annular portion of the disk. Rotation of the disk thereafter may move the fluid, under centrifugal action, along the face of the disk in a radial direction away from the rotation axis. The outer periphery of the disk may be spaced from the housing to permit fluid to pass, by centrifugal action, from the outer periphery of the disk toward the second chamber. 
     In yet another aspect the disclosure provides a drive arrangement having a housing having a motor casing and a gear train casing. A motor is contained in a motor chamber of the motor casing and a gear train contained in a gear chamber of the gear train casing. The motor may have a shaft rotatable about a rotation axis. A partition within the housing between the motor casing and gear train casing may allow fluid communication between the motor and gear chambers. A disk mounted to the shaft for co-rotation about the rotation axis may have an outer periphery and an annular portion having a face with entraining surface features for stimulating fluid transport of the rotating disk. The face of the disk may be spaced along the rotation axis from the partition by a gap clearance. The gap clearance may have an axial dimension selected such that rotation of the disk creates a pressure gradient drawing fluid from a direction of the motor chamber through the gap clearance in a radial direction toward the rotation axis to an inner diameter of the annular portion of the disk. Rotation of the disk thereafter may move the fluid, under centrifugal action, along the face of the disk in a radial direction away from the rotation axis. The outer periphery of the disk may be spaced from the housing to permit fluid to pass, by centrifugal action, from the outer periphery of the disk toward the gear chamber. 
     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 perspective view of an example work vehicle in the form of a self-propelled agricultural sprayer having an example drive arrangement according to this disclosure; 
         FIG. 2  is a schematic cross-sectional view of the example drive arrangement of  FIG. 1 ; 
         FIG. 3  is a simplified partial view of the schematic shown in  FIG. 2 ; and 
         FIGS. 4-6  are plan views of example disk configurations for use in the example drive arrangements, showing example annular friction areas having waffle, sunburst and spiral patterns, respectively. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     The following describes one or more example embodiments of a drive arrangement having a fluid transport arrangement with a rotating disk, 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. 
     In-line or axial drive arrangements may be used for propelling various agricultural and off-road vehicles. Such drive arrangements may include a motor assembly and a gear train assembly to provide gear reduction and increased torque. Design requirements may mandate that the space envelope for the drive arrangement be minimized resulting in components being closely configured, oftentimes within an integral casing or common housing. It may also be necessary to cool and lubricate the components of the drive arrangement with a liquid lubricating fluid. However, in systems having an electric motor assembly it is desirable to limit the amount of lubricating fluid in the motor casing, and thereby reduce windage and parasitic drag caused when the fluid is present in the annular gap between the rotor and the stator of the electric motor. 
     Conventional drives may have used air pressure within the motor chamber for displacing the lubricating fluid. This approach has known disadvantages including aeration of the lubricating fluid, increased costs associated with compressing and routing the air through the motor assembly, cold performance issues and introduction of dirt and water from the compressed air into the drive assembly. 
     The drive arrangement proposed in this disclosure includes a simple mechanical fluid transport mechanism in the form of a rotating disk, which may be readily packaged on the drive shaft between the motor assembly and the gear train assembly. An annular portion of the rotating disk may be proximate to a partition in the housing by a controlled gap distance and configured to produce a negative pressure gradient, which draws lubricating fluid out from the motor casing towards the gear train casing. The rotating disk may be a clutch plate or friction brake element with a splined shaft positioned on the drive shaft of the motor assembly. A loose clearance may be provided between the disk and the housing to minimize windage and optimize lubricating fluid transport. 
     In certain embodiments, the disclosed drive arrangement, and in particular the location of the rotating disk and the partition, define various passageways from the motor chamber to gear train chamber. As such, a single partition or multiple partitions may be provided in the drive arrangement housing. Similarly, a single disk or multiple disks may be provided, each having single-sided or double-sided fluid transport surface. Likewise, the configuration of the rotating disk may include certain features of the fluid transport surface(s) are formed on the face of the annular portion that may be improve the adhesion to, or carrying volume of, the disk, the negative pressure gradient, and/or the centrifugal force by entraining the lubricating fluid on the disk. Thus, the rotation disk provides a low cost and robust method of moving lubricating fluid from the motor assembly to other components of the drive arrangement. 
     With reference now to the drawings, example drive arrangements will be described in the context of a work vehicle in the form of a self-propelled agricultural sprayer in which the drive arrangement rotates a wheel assembly having a single wheel. While such a motorized sprayer is illustrated as an example work vehicle herein, one skilled in the art will recognize that the configuration of the drive arrangement disclosed herein may be readily adapted for use on other types work vehicles and/or wheel assemblies having multiple wheels (e.g., two wheels) for a given drive arrangement. As such, the present disclosure should not be limited to applications associated with drive arrangements for single wheel assemblies or self-propelled agricultural sprayers. 
     Referring now to  FIG. 1 , a high clearance, self-propelled agricultural sprayer  20  is shown having a main frame  22  supported for forward movement over the ground by a suspension  24  having a pair of front wheel assemblies  26  and a pair of rear wheel assemblies  28 . A body structure  30  includes a cab  32  supported on the frame  22  between the wheel assemblies  26 ,  28  and ahead of a stowable spraying assembly  34 . The spraying assembly  34  includes a pair of articulated spray booms  36 ,  38  positionable from a stowed configuration such that each boom  36 ,  38  is folded and extends generally parallel to the main frame  12  as shown in  FIG. 1  to a use position (not shown) such that each boom  36 ,  38  is unfolded and extends generally perpendicular to the main frame  12 . A drive arrangement  40  coupled to each of the wheel assemblies  26 ,  28  is operable to rotate the wheel assemblies  26 ,  28  for propelling the sprayer  12 . The drive arrangement  40  will be further described herein with reference to a front wheel assembly  26 ; however, one skilled in the art will appreciate that the rear wheel assembly  28  may also be powered by a drive arrangement  40  in a like manner. 
     With reference to  FIG. 2 , the drive arrangement  40  may include a motor assembly  42  having a motor casing  44  housing an electric motor  46  in a motor chamber  48  and a gear train casing  50  housing a gear train assembly  52  in a gear train chamber  54 . A drive shaft  56  of the motor assembly  42  is rotatably coupled to the gear train assembly  52 . An output shaft  58  from the gear train assembly  52  is coupled to a wheel hub  60  associated with the wheel assembly  26 . A torque generated by the electric motor  46  is transmitted through the gear train assembly  52 , which provides gear reduction and torque amplification, is delivered to the wheel assembly  26  for propelling the sprayer  20 . In this way, the drive arrangement  40  may be referred to as an in-line or coaxial drive arrangement in which the motor assembly  42  and the drivetrain or gear train assembly  52  are aligned on a common axis, and the drive shaft  56  and the output shaft  58  would have a common axis of rotation A. 
     The drive shaft  56  may be supported in the motor casing  44  on bearings  62  for rotation about the axis of rotation A. By way of example, the electric motor  46  may include a rotor  64  formed on the drive shaft  56  and a stator  66  fixed in the motor casing  44 . The drive shaft  56  extends through a first partition defined by an end wall  68  of the motor casing  44  and a second partition defined by an end wall  70  of the gear train casing  50 . 
     As illustrated in  FIG. 2 , by way of example, the gear train assembly  52  may include a first planetary gear set  72 , a clutch mechanism  74 , a brake mechanism  76  and a second gear set  78 . The first planetary gear set  72  may include a sun gear  80  fixed for rotation on the drive shaft  56 , a set of planetary gears  82  rotatably supported on a carrier plate  84  and engaging the sun gear  80 , and a ring gear  86  rotatably supported on the drive shaft  56  and engaging the planetary gears  82 . The clutch mechanism  74 , situated between the ring gear  86  and the gear train casing  50 , selectively couples the ring gear  86  and the gear train casing  50 . 
     An intermediate shaft  88  may extend from the carrier plate  84  to rotatably couple the first gear set  72  with an input side of the second gear set  78 . The braking mechanism  76 , situated between the intermediate shaft  88  and the gear train casing  50 , may provide frictional braking between the first and second gear sets  72 ,  78 . An output side of the second gear set  78  is rotatably coupled to the output shaft  58 . While the second gear set  78  may include a planetary gear set (not shown), one skilled in the art will recognize that alternate or additional gear assemblies may be used to achieve the desired torque and speed characteristics of the drive arrangement  40 . A set of bearings  90  may rotatably support the drive shaft  56  on the motor casing  44 . 
     With particular reference to  FIGS. 2 and 3 , an annular wall  92  may extend radially inward from a sidewall  94  of the motor casing  44 , generally parallel to the end walls  68 ,  70 . The annular wall  92  forms a partition within the motor casing  44  between the motor chamber  48  and the gear train chamber  54 , while allowing fluid communication there between (e.g., via various holes, slots, gaps or other openings). As illustrated in the figures, the annular wall  92  may be formed as part of the motor casing  44 . However, one skilled in the art should appreciate that the annular wall  92  may be a separate component fixedly secured to the motor casing  44 . 
     An annular space  96  is defined axially between the annular wall  92  and the end wall  70  of the gear train casing  50  along a rotation axis A. A disk  98  is located in the annular space  96  and fixed for rotation on the drive shaft  56  (with a splined shaft or similar configuration) between the end walls  68 ,  70 . The disk  98  includes an annular portion  100  terminating at an outer periphery  102  that is spaced radially inward from the sidewall  94 . A face  104  of the disk  98  is spaced along the rotational axis A from the annular wall  92  by a gap clearance G. 
     The face  104  of the annular portion  100  may include frictional or entraining surface features  106  (e.g., as shown in  FIG. 5 ) for stimulating and improving the fluid transport capabilities of the disk  98 . However, the features  106  may not be included or required in various applications. Furthermore, it should be understood that the radial extent of the annular portion  100  might vary for a given application. For example, the annular portion  100  may extend radially inward only as far as the annular wall  92  or alternately to an inner portion of the disk  98 . In this regard, the disk  98  may be a clutch disk or brake friction element typically used in the drive arrangement  40 . 
     Referring also to  FIGS. 4-6 , the disk  98 ,  98 ′,  98 ″ may be monolithic structure of a uniform material with surface treatment in any of various forms (e.g., etching, scoring, laser cutting, printing, etc.) providing the surface features  106 ,  106 ′,  106 ″, or it may be a composite structure, for example, having a metal substrate with a paper or composite material laminated thereon to form the annular portion  100 . As mentioned, the surface features  106  formed in the face  104  of the disk  98  may stimulate fluid transport to the disk  98  and/or aid in carrying fluid on the disk  98 . These features may be in any arrangement or take any form. They may be raised from, or recessed into, the nominal radial surface of the disk  98 . For example, the surface features  106  may include a grid of channels or grooves ( FIG. 4 ) in the face  104  to form a waffle pattern. Alternately, the surface features  106 . 1  may include a series of angular channels arranged in a crossing manner ( FIG. 5 ) to form a sunburst pattern, or the surface features  106 . 2  may include series of channels arranged in a parallel manner ( FIG. 6 ) to form a spiral pattern. Other surface features for the face  104  may be devised that promote a radially outward spiral, slinging action of fluid entrained on the face  104  as the disk  98  is rotated. 
     One or more ports  108  formed through the end wall  68  of motor casing  44  and one or more ports  110  formed through the end wall  70  of gear train casing  50  provide fluid communication, such as a fluid passageway  112  ( FIG. 3 ), between the motor chamber  48  and the gear train chamber  54 . While ports  108 ,  110  are shown in the drawings as a single opening through the bottom of end walls  68 ,  70 , one skilled in the art will appreciate that ports  108 ,  110  may include multiple openings angularly spaced in the end wall  68 ,  70  to move fluid there through. The fluid passageway  112  includes a first section  112   a  extending from port  108  radially inward between the end wall  68  and the annular wall  92 , a second section  112   b  extending radially outward between the annular wall  92  and the face  106  of the disk  98 , and a third section  112   c  extending axially between the outer periphery  102  of the disk  98  and the side wall  94  to the port  110 . 
     As noted above, the drive arrangement  40  generally has liquid lubricating and cooling fluid circulating through the gear train assembly  52 . During operation, liquid fluid F may migrate from the gear train chamber  54  into the motor chamber  48 . Once in the motor chamber  48 , the fluid F may be trapped in the gap between the rotating rotor  64  and the fixed stator  66  increasing windage and parasitic drag on the electric motor  46 . 
     The rotating disk  98  addresses this situation by creating a pressure differential in the passageway  112  to draw the fluid F out of the motor chamber  48  and into the gear train chamber  54 . In particular, the fluid F in the annular space  96  creates a pressure gradient resulting from increasing angular velocity from the inner edge to the outer edge of the annular portion  100  of the disk  98  (i.e., a negative pressure gradient) to draw the fluid F through the first section  112   a  of the passageway  112 . Once in contact with the annular portion  100  of the disk  98 , the fluid F is moved through the second and third passageway  112   b ,  112   c  by a centrifugal force generated by the rotating disk  98 . 
     With this understanding of the fluid transport arrangement, it should be appreciated that the configuration and spacing of certain elements in the drive arrangement are important to provide an efficient and effective fluid transport mechanism. For example, the axial dimension of gap clearance G is effective for adjusting the pressure differential created. A gap clearance G that is too large may not create an adequate pressure gradient to draw fluid from the motor casing  44  through the first passageway  112   a . Conversely, a gap clearance G that is too small may increase the drag on the fluid F flowing through the first passageway. The length of the second passageway  112   b  as defined by the height H of the annular wall  92  relative to the locations of ports  108 ,  110  may also impact the pressure differential. If the annular wall is too short the pressure gradient may be too small. Conversely, if the annular wall is too long, the fluid F will stall in the second passageway  112   b . The specific dimensions for the gap clearance and the wall height will be dictated by the specific application including the rotational velocity of the disk  98  and the viscosity of the fluid F. Example gap clearance dimensions may range from 0.1 mm to 0.5 mm for example disk diameter dimensions ranging from 40 mm to 200 mm. The larger the diameter of disk  98 , the larger the gap clearance distance should be as well as the larger the annular gap at the outer periphery (i.e., the outer diameter) of the disk  98  to reduce windage losses. 
     Referring again to  FIG. 3 , the port  110  may formed anywhere in the end wall  70  within an annular radial band coextensive with the annular wall  92 . However, locating the port  110  through the end wall  70  at a radially outermost location in the gear train casing  50  may have the advantage of requiring less energy to overcome gravity. For example, locating the port  110  radially inward along the end wall  70  may unnecessarily create a pressure head due to a height difference between the third passageway  112   c  and the port  110  leading to less efficient fluid transport. 
     In some instances, it may be beneficial to form holes through the rotating disk  98  for transporting lubricating fluid to the back  114  thereof. Lubricating fluid F flowing on both sides  104 ,  114  of the annular portion  100  may increase the pressure gradient and/or decrease the fluid drag in the second passageway  112   b . In this case, the back of the annular portion  100  may include frictional or entraining surface features, similar to those shown in  FIGS. 4-6  for the face  104 , for stimulating and effecting fluid transport. 
     Having explained the fundamental concepts of the disclosure in terms of an example embodiment for the drive arrangement  40 , certain additions and/or modifications to these concepts will be understood. One skilled in the art will appreciate that the number, configuration and arrangement of the ports, walls and rotating disk, as well as the design of any surface features can be varied according to the particular application and packaging associated with the drive arrangement. For example, a second, opposite face of the rotating disk may be provided with second annular portion having entraining surface features to carry fluid in the manner described above. Also, one or more additional rotating disks, and corresponding annular walls as needed, may be provided to entrain and move fluid, thereby increasing the fluid carrying capacity of the system. Such combinations and/or modifications are fully contemplated by the spirit and scope of the disclosure provided herein. 
     Moreover, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. Thus, it will be appreciated that the term “axial” as used herein refers to a direction that is generally parallel to an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder with a centerline and opposite, circular ends, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally in parallel with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending perpendicularly outward from a shared centerline, axis, or similar reference. For example, two concentric and axially overlapping cylindrical components may be viewed as “radially” aligned over the portions of the components that axially overlap, but not “radially” aligned over the portions of the components that do not axially overlap. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). 
     Similarly, 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 any use of the terms “comprises” and/or “comprising” in this specification specifies 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 implementations other than those explicitly described are within the scope of the claims.