Co-axial motors for dual drive planetary drive system

Abstract

A drive system, a vehicle incorporating the drive system, and a method for operating the drive system are disclosed herein. The drive system can include a planetary drive, a first motor, and a second motor. The planetary drive set can have a sun member, a ring member, planet members positioned operably between the sun and ring members, and a planet carrier engaged with each of the planet members. The first motor can have a first stator and a first rotor and centered on a longitudinal axis. The second motor can have a second stator and a second rotor and centered on the longitudinal axis. The second motor can be nested within the first motor. The first rotor can be fixed for rotation with the ring member and the second rotor can be fixed for rotation with the sun member.

Description

CO-AXIAL MOTORS FOR DUAL DRIVE PLANETARY DRIVE SYSTEMBACKGROUND1. Field

[0001] The present disclosure relates to drive systems, especially systems in which an input is directed into a planetary gear set and produces an output from the planetary gear set.2. Description of Related Prior Art

[0002] U.S. Pub. No. 2012 / 0035014 discloses TRANSMISSION SYSTEMS. The transmission systems includes an input (22), an output (34) and an epicyclic geartrain comprising first and second gearsets. The first gearset comprises a first sun gear (2) in mesh with a set of first planet gears (4), which are rotatably carried by a first planet carrier (6) and are in mesh with a first annulus gear (8). The second gearset comprises a second sun gear (10), which is connected to rotate with the first sun gear (2) and is in mesh with a set of second planet gears (12), which are rotatably carried by a second planet carrier (14) and are in mesh with a second annulus gear (18). One of the planet carriers (6) of one of the gearsets is connected to rotate with the annulus gear ( 18) of the other gearset. The two connected sun gears (2), (10) and the input (22) are connected to the rotors (24, 20) of respective electric motor generators (E2, El), the electrical stator connections of which are connected together via a controller (30) arranged to control the flow of electrical power between them. The input (22) is selectably connectable to the other (14) of the planet carriers and to the other (8) of the annulus gears by first (C2) and second (Cl) selectably operable clutches, respectively, whereby the transmission system has two regimes. FIG. 2 of the ‘014 publication discloses an embodiment in which two motor / generators are nested within one another and the rotor 20 of El is situated outside the stator 26 and not inside it.

[0003] The background description provided herein is for the purpose of generally presenting background context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] This section provides a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview and is not intended toAtty Ref: 112540-0009.W01 - 1 -identify “key” or “critical” elements of the present disclosure or to delineate the scope of the various aspects described herein. The purpose of this portion of the document is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0005] A drive system can include a first planetary drive, a first motor, and a second motor. The first planetary drive set can have a first sun member, a first ring member, a first plurality of planet members positioned operably between the first sun member and the first ring member, and a first planet carrier engaged with each of the first plurality of planet members. The first motor can have a first stator and a first rotor and centered on a first longitudinal axis. The second motor can have a second stator and a second rotor and centered on the first longitudinal axis. The second motor can be nested within the first motor. The first rotor can be fixed for rotation with the first ring member and the second rotor can be fixed for rotation with the first sun member.

[0006] According to other features, the first ring member can extend along the first longitudinal axis between a first side and a second side. The first side of the first ring member can be directed toward the first stator along the first longitudinal axis. The first side can be closer to the first stator than the second side along the first longitudinal axis. A mechanical interconnection between the first rotor and the first ring member may not extend past the second side of the first ring member. The first rotor can be connected to the first side of the first ring member.

[0007] In other features, the first ring member can extend along the first longitudinal axis between a first side and a second side. The second side of the first ring member can be directed away from the first stator along the first longitudinal axis. The first side can be closer to the first stator than the second side along the first longitudinal axis. The first ring member can be positioned between the first planet carrier and the first stator along the first longitudinal axis. A mechanical interconnection between the first rotor and the first ring member may not extend past or overlap the first planet carrier along the first longitudinal axis. The drive system can also include an output shaft that can be engaged with the first planet carrier for concurrent rotation, wherein the output shaft can be positioned only on the second side of the first ring member along the first longitudinal axis.

[0008] According to additional features, the first ring member can extend normal to the first longitudinal axis between a radially-inner surface and a radially-outer surface. The first rotor and the first ring member can be non-selectively fixed for rotation together. The drive system can also include a heat transfer member positioned radially between the first stator and the second stator. The first stator and second stator can share a plurality of stator laminations. Each of the plurality of stator laminations can have a first set of stator teeth facing radially outwards and supporting a first windingAtty Ref: 112540-0009.W01 - 2 -for driving the first rotor and can also have a second set of stator teeth facing radially inwards and supporting a second winding for driving the second rotor.

[0009] According to other features, the drive system can also include at least one brake selectively engageable with one of the first rotor and the second rotor to selectively inhibit rotation of the one of the first rotor and the second rotor. The first motor and the second motor can be positioned between the first planetary drive set and the at least one brake. The at least one brake can be further defined as a first brake selectively engageable with the first rotor to selectively inhibit rotation of the first rotor and a second brake selectively engageable with the second rotor to selectively inhibit rotation of the second rotor.

[0010] In other features, the drive system can also include a second planetary drive set having a second sun member, a second ring member, a second plurality of planet members positioned operably between the second sun member and the second ring member, and a second planet carrier engaged with each of the second plurality of planet members. The drive system can also further include a third motor having a third stator and a third rotor and centered on the first longitudinal axis. The drive system can also further include a fourth motor having a fourth stator and a fourth rotor and can be centered on the first longitudinal axis and nested within the third motor. The third rotor can be fixed for rotation with the second ring member. The fourth rotor can be fixed for rotation with the second sun member. The second rotor and the fourth rotor can be engaged with one another for concurrent rotation.

[0011] A vehicle can include a chassis, a first wheel, and a first drive system. The first drive system can be positioned on the chassis. The first drive system can have a first planetary drive set having a first sun member, a first ring member, a first plurality of planet members positioned operably between the first sun member and the first ring member, and a first planet carrier engaged with each of the first plurality of planet members. The first drive system can also have a first motor having a first stator and a first rotor and centered on a first longitudinal axis. The first drive system can also have a second motor having a second stator and a second rotor and centered on the first longitudinal axis and nested within the first motor. The first rotor can be fixed for rotation with the first ring member. The second rotor can be fixed for rotation with the first sun member. The first wheel can be engaged with the first planet carrier for concurrent rotation.

[0012] According to additional features, the vehicle can also include a second wheel and a second drive system. The second drive system can be positioned on the chassis. The second drive system can include a second planetary drive set having a second sun member, a second ring member, a second plurality of planet members positioned operably between the second sun member and theAtty Ref: 112540-0009.W01 - 3 -second ring member, and a second planet carrier engaged with each of the second plurality of planet members. The second drive system can also include a third motor having a third stator and a third rotor and can be centered on the first longitudinal axis. The second drive system can also include a fourth motor having a fourth stator and a fourth rotor and can be centered on the first longitudinal axis and can be nested within the third motor. The third rotor can be fixed for rotation with the second ring member. The fourth rotor can be fixed for rotation with the second sun member. The second wheel can be engaged with the second planet carrier for concurrent rotation. The second rotor and the fourth rotor can be engaged with one another for concurrent rotation.

[0013] A method of operating a vehicle having a chassis can include driving a first wheel upon which the chassis is supported to thereby move the chassis. The driving includes controlling, with a controller, a first motor, positioned on the chassis and centered on a first longitudinal axis, to rotate a first rotor of the first motor in a first direction at a first speed of rotation. The driving also includes controlling, with the controller, a second motor, nested in the first motor and positioned on the chassis and centered on the first longitudinal axis, to rotate a second rotor of the second motor in a second direction at a second speed of rotation. The first rotor can be mechanically coupled to the first wheel through a first ring member of a first planetary drive set positioned on the chassis. The second rotor can be mechanically coupled to the first wheel through a first sun member of the first planetary drive set.

[0014] According to other features, the driving can be further defined as driving the wheel at a third speed by the controlling the first motor and the controlling the second motor being further defined such that the first direction and the second direction are the same.

[0015] In other features, the driving can be further defined as driving the wheel at a fourth speed less than the third speed by the controlling of the first motor being further defined such that the first speed is zero revolutions per minute and also by the controlling of the second motor being further defined such that the second speed is greater than zero revolutions per minute.

[0016] According to additional features, the driving can be further defined as driving the wheel at a fifth speed less than the fourth speed by one of the controlling of the first motor being further defined such that the first speed is greater than zero revolutions per minute and the controlling of the second motor being further defined such that the second speed is zero revolutions per minute or the controlling of the first motor and the controlling the second motor being further defined such that the first direction and the second direction are opposite to one another.

[0017] According to other features, the method can also include driving a second wheel upon which the chassis is supported to thereby move the chassis. The driving of the second wheel canAtty Ref: 112540-0009.W01 - 4 -include controlling, with the controller, a third motor, positioned on the chassis and centered on the first longitudinal axis, to rotate a third rotor of the third motor in a third direction at a third speed of rotation. The driving of the second wheel can also include controlling, with the controller, a fourth motor, nested in the third motor and positioned on the chassis and centered on the first longitudinal axis, to rotate a fourth rotor of the fourth motor in a fourth direction at a fourth speed of rotation. The third rotor can be mechanically coupled to the second wheel through a second ring member of a second planetary drive set positioned on the chassis and the second rotor can be mechanically coupled to the second wheel through a second sun member of the second planetary drive set. The controlling of the second motor and the controlling of the fourth motor can be further defined wherein the second speed and the fourth speed are the same and the second direction and the fourth direction are the same. The controlling of the first motor and the controlling of the third motor can be further defined wherein the first speed and the third speed are different and the first direction and the third direction are the same.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The detailed description set forth below references the following drawings:

[0019] Figure 1 is a schematic cross-section of a drive system according to an exemplary embodiment of the present disclosure;

[0020] Figure 2 is a schematic cross-section of a drive system according to another exemplary embodiment of the present disclosure; and

[0021] Figure 3 is a schematic view of a vehicle incorporating drive systems as disclosed in Figure 1.DETAILED DESCRIPTION

[0022] A plurality of different embodiments of the present disclosure is shown in the Figures of the application. Similar features are shown in the various embodiments of the present disclosure. Similar features across different embodiments have been numbered with a common reference numeral and have been differentiated by an alphabetic suffix. Also, to enhance consistency, the structures in any particular drawing share the same alphabetic suffix even if a particular feature is shown in less than all embodiments. Similar features are structured similarly, operate similarly, and / or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.Atty Ref: 112540-0009.W01 - 5 -

[0023] The present disclosure, as demonstrated by the exemplary embodiments, described below, can provide a drive system, vehicle incorporating the drive system, and method for operating the drive system. The drive system can provide a continuously variable motion transmission ratio. The exemplary embodiments include a planetary drive set in the form of a gear set. The drive system can efficiently achieve either high torque at low speeds or low torque at high speeds.

[0024] The exemplary drive system applies a co-axial motor approach wherein a first motor can be an outer rotor BLDC (brushless direct current) motor coupled to a ring member of a planetary drive set and a second motor can be an inner rotor BLDC motor coupled to the sun gear of the planetary drive set. The first and second motors can be in a co-axial and nested relationship with one another wherein the stator of the sun motor occupies an inside diameter of the stator of the ring motor. It should be noted that the ring motor could instead be coupled to the carrier, wherein the ring is the output. In various embodiments, such as those exemplary embodiments disclosed herein, the carrier can be the output. In another embodiment, the sun motor could instead be coupled to the carrier and the sun gear configured as the output.

[0025] Referring now to Figure 1, an exemplary drive system 10 can include an exemplary first planetary drive set 12. The exemplary first planetary drive set 12 includes an exemplary first sun member 14. The exemplary first planetary drive set 12 also includes an exemplary first ring member 16. The exemplary first planetary drive set 12 also includes a first plurality of planet members, such as planet members 18, 20. The exemplary planet members 18, 20 are positioned operably between the exemplary first sun member 14 and the exemplary first ring member 16. The exemplary first planetary drive set 12 also includes an exemplary first planet carrier 22 engaged with each of the first plurality of exemplary planet members 18, 20. The exemplary first planetary drive set 12 is a gear set, wherein exemplary first ring member 16 is a gear, the planet members 18, 20 are gears, and the sun member 14 is a gear. But a friction drive set could be applied in other embodiments of the present disclosure, such as disclosed in US11002345, which is hereby incorporated by reference in its entirety.

[0026] The exemplary drive system 10 also includes an exemplary first motor 24. The exemplary first motor 24 has an exemplary first stator 26. The exemplary first motor 24 also has an exemplary first rotor 28. The exemplary first motor 24 is centered on an exemplary first longitudinal axis 30.

[0027] The exemplary drive system 10 also includes an exemplary second motor 32. The exemplary second motor 32 has an exemplary second stator 34. The exemplary second motor 32 alsoAtty Ref: 112540-0009.W01 - 6 -has an exemplary second rotor 36. The exemplary second motor 32 is centered on the exemplary first longitudinal axis 30. The exemplary second motor 32 is nested within the exemplary first motor 24.

[0028] The exemplary first rotor 28 is fixed for rotation with the exemplary first ring member 16. The exemplary second rotor 36 is fixed for rotation with the exemplary first sun member 14.

[0029] Figure 1 also shows the exemplary first planetary drive set 12, the exemplary first motor 24, and the exemplary second motor 32 are contained in an interior of an exemplary housing 38. The interior of the exemplary housing 38 can be closed at opposite ends by exemplary covers 40, 42. The exemplary drive system 10 also includes various bearings, which are illustrated in Figure 1 as blocks, such as referenced at 44 and 46. Figure 1 also shows an exemplary output shaft 48 fixed for concurrent rotation with the exemplary first planet carrier 22. Figure 1 also shows an exemplary shaft 50 fixed for concurrent rotation with the exemplary second rotor 36.

[0030] As is also shown in Figure 1, the exemplary first ring member 16 extends along the exemplary first longitudinal axis 30 between an exemplary first side 52 and an exemplary second side 54. The exemplary first side 52 of the exemplary first ring member 16 is directed toward the exemplary first stator 26 along the exemplary first longitudinal axis 30. The exemplary first side 52 is closer to the exemplary first stator 26 than the exemplary second side 54 along the exemplary first longitudinal axis 30.

[0031] As is also shown in Figure 1, a mechanical interconnection between the exemplary first rotor 28 and the exemplary first ring member 16 does not extend past the exemplary second side 54 of the exemplary first ring member 16. A mechanical interconnection can include a direct connection in various embodiments of the present disclosure. The exemplary first rotor 28 is directly connected to the exemplary first ring member 16. In the exemplary embodiment shown in Figure 1, the mechanical interconnection is a direct connection between the exemplary first rotor 28 and the exemplary first side 52 of the exemplary first ring member 16. In other embodiments, a direct mechanical interconnection can be defined by the exemplary first rotor 28 directly connected to a radially top side 56 of the exemplary first ring member 16. A mechanical interconnection of the present disclosure can also include an indirect connection. For example, there could be a mechanical member such as, by way of example and not limitation, a cylinder or a ring or one or more struts interposed between the exemplary first rotor 28 the exemplary first ring member 16. Arranging the mechanical interconnection between the exemplary first rotor 28 and the exemplary first ring member 16 such that it does not extend past the exemplary second side 54 of the exemplary first ring member 16 makes embodiments of the present disclosure more compact, which in turn increases the torque density of the system.Atty Ref: 112540-0009.W01 - 7 -

[0032] The exemplary first ring member 16 is positioned between the exemplary first planet carrier 22 and the exemplary first stator 26 along the exemplary first longitudinal axis 30. The exemplary mechanical interconnection between the exemplary first rotor 28 and the exemplary first ring member 16 does not extend past or overlap the exemplary first planet carrier 22 along the exemplary first longitudinal axis 30. Arranging the mechanical interconnection between the exemplary first rotor 28 and the exemplary first ring member 16 such that it does not extend past or overlap the planet carrier makes embodiments of the present disclosure more compact, which in turn increases the torque density of the system.

[0033] The exemplary output shaft 48 is engaged with the exemplary first planet carrier 22 for concurrent rotation. In other words, the two components rotate together. The exemplary output shaft 48 is positioned only on the exemplary second side 54 of the exemplary first ring member 16 along the exemplary first longitudinal axis 30. The exemplary output shaft 48 and the exemplary first planet carrier 22 are engaged to one another by being separately-formed and subsequently joined together. In other embodiments, the exemplary output shaft 48 and the exemplary first planet carrier 22 can be engaged to one another by being integrally-formed.

[0034] The exemplary first ring member 16 extends normal to the exemplary first longitudinal axis 30 between a radially-inner surface 58 and the radially-outer surface 56. The exemplary first rotor 28 and the exemplary first ring member 16 are non-selectively fixed for rotation together. In other words, the exemplary first ring member 16 rotates whenever the exemplary first rotor 28 rotates. The exemplary first rotor 28 and the exemplary first ring member 16 can be non-selectively fixed, directly or indirectly, for rotation together.

[0035] The exemplary drive system 10 also includes an exemplary heat transfer member 60. The exemplary heat transfer member 60 is positioned radially between the exemplary first stator 26 and the exemplary second stator 34. The exemplary heat transfer member 60 is tube-shaped, having a radially-inner side 62 and a radially-outer side 64 and extending along the exemplary first longitudinal axis 30 between a first end 66 and a second end 68. The exemplary heat transfer member 60 is configured to redirect heat flow from a radial direction from the laminations of the exemplary first stator 26 and the exemplary second stator 34 into an axial direction along the exemplary first longitudinal axis 30, to direct heat axially to an exemplary heat sink 70.

[0036] A heat transfer member included in one or more embodiments of the present disclosure could be solid or fully or partially hollow, with one or more input ports and one or more output ports, to allow for the passage of a flowable liquid or gas heat exchange medium. The exemplary heat transfer member 60 is solid. A heat transfer member included in one or more embodiments of theAtty Ref: 112540-0009.W01 - 8 -present disclosure could be formed from one or more various materials, including copper, aluminum, or a thermally conductive epoxy. A heat transfer member included in one or more embodiments of the present disclosure could be some combination of materials, such as by way of example and not limitation, a copper ring with some flowable thermally conductive material on both the outer diameter and inner diameter of the copper ring to ensure optimal heat transfer from the lamination into the copper and subsequently into the heat sink.

[0037] In one or more embodiments of the present disclosure, the first stator and second stator could share a plurality of stator laminations. Each of such stator laminations would have a first set of stator teeth facing radially outwards and supporting a first winding for driving the exemplary first rotor 28. Each of such stator laminations would also have a second set of stator teeth facing radially inwards and supporting a second winding for driving the exemplary second rotor 36. In such embodiments, a heat transfer member could include a plurality of discrete tubes positioned equidistantly about the longitudinal axis 30 and extending through apertures defined in the shared stator laminations.

[0038] The exemplary drive system 10 also includes at least one brake selectively engageable with one of the exemplary first rotor 28 and the exemplary second rotor 36 to selectively inhibit rotation of the one of the exemplary first rotor 28 and the exemplary second rotor 36. In the exemplary embodiment, the exemplary drive system 10 includes a first brake 72 selectively engageable with the exemplary first rotor 28 to selectively inhibit rotation of the exemplary first rotor 28. In the exemplary embodiment, the exemplary drive system 10 also includes a second brake 74 selectively engageable with the exemplary second rotor 36 to selectively inhibit rotation of the exemplary second rotor 36. The exemplary first motor 24 and the exemplary second motor 32 are positioned between the exemplary first planetary drive set 12 set and the brake 74. The exemplary drive system 10 also includes a third brake 76 selectively engageable with the exemplary output shaft 48 to selectively inhibit rotation of the exemplary output shaft 48. Any one or all of the exemplary brakes 72, 74, 76 can be an inductive brake, a pin-style brake wherein a linear motion enabled by a solenoid, or similar, brings a pin coupled to the chassis into engagement with the moving members, or an electrostatic brake as detailed in US 10355624 and US2024 / 0213892, which are hereby incorporated by reference. It is noted that if the brakes 72 and 74 have sufficient braking torque for a particular application then the brake 76 can be eliminated.

[0039] As is also shown in Figure 1, exemplary drive system 10 also includes a support structure 78 that supports the exemplary brake 72. The exemplary support structure 78 also supports an exemplary encoder 80 of the exemplary drive system 10. The exemplary encoder 80 is configuredAtty Ref: 112540-0009.W01 - 9 -to sense the rotational position and velocity of the exemplary first rotor 28. The exemplary drive system 10 also includes an exemplary encoder 82 configured to sense the rotational position and velocity of the exemplary second rotor 36. The exemplary drive system 10 also includes an exemplary encoder 84 configured to sense the rotational position and velocity of the exemplary output shaft 48. One or all of the encoders 80, 82, 84 can be one of many commonly available technologies used in the art. One example is a capacitive encoder that is disclosed in US6492911 which is hereby incorporated by reference. In addition, optical, magnetic, and inductive encoders are possible options as well.

[0040] The exemplary drive system 10 also includes an exemplary controller 86. The exemplary controller 86 is configured to receive signals from the exemplary encoders 80, 82, 84. The exemplary controller is also configured to control the operation of the first motor 24, the second motor 32, and the brakes 72, 74, 76. The operation of the exemplary drive system 10 will be described in greater detail below.

[0041] Figure 2 shows an alternative embodiment of the present disclosure. An exemplary drive system 10a can include an exemplary first planetary drive set 12a. The exemplary first planetary drive set 12a includes an exemplary first sun member 14a. The exemplary first planetary drive set 12a also includes an exemplary first ring member 16a. The exemplary first planetary drive set 12a also includes a first plurality of planet members, such as planet members 18a, 20a. The exemplary planet members 18a, 20a are positioned operably between the exemplary first sun member 14a and the exemplary first ring member 16a. The exemplary first planetary drive set 12a also includes an exemplary first planet carrier 22a engaged with each of the first plurality of exemplary planet members 18a, 20a. The exemplary first planetary drive set 12a is a gear set, wherein exemplary first ring member 16a is a gear, the planet members 18a, 20a are gears, and the sun member 14a is a gear. But a friction drive set could be applied in other embodiments of the present disclosure.

[0042] The exemplary drive system 10a also includes an exemplary first motor 24a. The exemplary first motor 24a has an exemplary first stator 26a. The exemplary first motor 24a also has an exemplary first rotor 28a. The exemplary first motor 24a is centered on an exemplary first longitudinal axis 30a.

[0043] The exemplary drive system 10a also includes an exemplary second motor 32a. The exemplary second motor 32a has an exemplary second stator 34a. The exemplary second motor 32a also has an exemplary second rotor 36a. The exemplary second motor 32a is centered on the exemplary first longitudinal axis 30a. The exemplary second motor 32a is nested within the exemplary first motor 24a.Atty Ref: 112540-0009.W01 - 10 -

[0044] The exemplary first rotor 28a is fixed for rotation with the exemplary first ring member 16a. The exemplary second rotor 36a is fixed for rotation with the exemplary first sun member 14a.

[0045] The exemplary drive system 10a also includes a controller 86a. A distinction between the first embodiment shown in Figure 1 and the second embodiment shown in Figure 2 is that the controller 86a is positioned differently, outside of a portion of a housing the holds the first and second motors 24a and 32a. An exemplary controller that can be utilized in the exemplary embodiments disclosed herein can be Texas Instruments F2800137PT, but other commercially available microcontrollers could be selected.

[0046] Figure 3 discloses an exemplary vehicle 88 having an exemplary chassis 90, an exemplary first wheel 92, and the first exemplary drive system 10. The first exemplary drive system 10 is positioned on the exemplary chassis 90. The exemplary first wheel 92 is engaged with the exemplary first planet carrier 22 for concurrent rotation.

[0047] Figure 3 also discloses that the exemplary vehicle 88 has further wheels 94, 96, and 98. Figure 3 also discloses that exemplary drive systems 110, 210, and 310 are also positioned in the exemplary chassis 90 of the exemplary vehicle 88. The exemplary drive systems 10, 110, 210, 310 are identical. The exemplary drive systems 10, 110, 210, 310 are respectively coupled to the wheels 92, 94, 96, 98 and respectively drive the wheels 92, 94, 96, 98 in rotation. The exemplary second rotor 36 of the exemplary drive system 10 and the second rotor of the exemplary drive system 110 are engaged with one another for concurrent rotation. The exemplary second rotor of the exemplary drive system 210 and the second rotor of the exemplary drive system 310 are engaged with one another for concurrent rotation, through an exemplary connecting shaft 102. Figure 3 discloses two sun motors each within their own nested positions coupled by a shaft; they can be understood as one motor and driven by one drive. It is noted that the present disclosure also contemplates an arrangement in which the sun motors can be combined into one larger motor outside of the nested position in between the two ring drives.

[0048] Figure 3 also discloses an exemplary controller 100 of the exemplary vehicle 88. The exemplary controller 100 can be configured to execute control over the exemplary drive systems 10, 110, 210, 310 and the respective controller of each of the exemplary drive systems 10, 110, 210, 310. The Texas Instruments F2800137PT or another commercially available microcontroller could be utilized as the exemplary controller 100. The exemplary controller 100 can be separate from exemplary controllers 86, wherein each exemplary drive system 10, 110, 210, 310 can have a controller 86 that communicates to controller 100 or controller 100 can include the elements ofAtty Ref: 112540-0009. W01 - 11 -controller 86 within it wherein controller 100 has direct access to each motor, brake, and controller for two or more drives.

[0049] Figure 3 also schematically shows a power source, referenced at 104. The exemplary power source 104 can be configured to provide power to the motors of the exemplary drive systems 10, 110, 210, 310. In one or more embodiments of the present disclosure, the power source 104 can be a battery or a plurality of batteries. The flow of power from and to the power source can be controlled by the exemplary controller 100.

[0050] A method of operating the exemplary vehicle 88 can include driving the exemplary first wheel 92 upon which the exemplary chassis 90 is supported to thereby move the exemplary chassis 90. It is noted that the following description for driving the exemplary first wheel 92 is applicable for driving any of the other wheels 94, 96, 98 as well. The step / operation of the driving can include controlling, with the controller 86 or the controller 100, the exemplary first motor 24 to rotate the exemplary first rotor 28 in a first direction at a first speed of rotation. The step / operation of the driving can include controlling, with the controller 86 or the controller 100, the exemplary second motor 32 to rotate the exemplary second rotor 36 in a second direction at a second speed of rotation.

[0051] The exemplary first motor 24 can be designed to run optimally within a first speed range and the exemplary second motor 32 can be designed to run optimally within a second speed range. The first and second speed ranges can be independent of one another.

[0052] The exemplary wheel 92 can be driven at a relatively high speed by controlling the exemplary first motor 24 and the controlling the exemplary second motor 32 such that the first direction and the second direction are the same. In other words, the exemplary sun member 14 and exemplary ring member 16 are rotated in the same direction. The exemplary sun member 14 and exemplary ring member 16 are additive with respect to one another and working together. This permits a high-speed range by permitting both motors 24, 32 to supply torque to the output at a smaller gear ratio resulting in higher speeds (herein referenced as support mode).

[0053] The exemplary wheel 92 can be driven at a relatively medium speed (less than high speed) by controlling the exemplary first motor 24 such that the first speed is zero revolutions per minute controlling the exemplary second motor 32 such that the second speed is greater than zero revolutions per minute. Thus, the first rotor 28 can be held stationary while the second rotor 36 can be rotated. For medium speed, the first rotor 28 can be stopped with the brake 72. The second rotor 36 would thus carry the load and supply all of the torque to the output shaft 48. This “medium” speed range can end when the second motor 32 reaches its top efficient speed.Atty Ref: 112540-0009. W01 - 12 -

[0054] The exemplary wheel 92 can be driven at a relatively low speed (less than medium speed) by alternative approaches. In one approach, the first motor 24 can be controlled such that the first speed is greater than zero revolutions per minute and the second motor 32 can be controlled such that the second speed is zero revolutions per minute. Thus, the first rotor 28 can be rotated while the second rotor 36 can be held stationary (herein referenced as ring mode). The second rotor 36 can be held stationary by engaging the brake 74.

[0055] In a second approach for “low” speed, the first motor 24 and the second motor 32 can be controlled such that the rotors 28 and 36 are rotated in opposite directions (herein referenced as ring subtract mode). This effectively increases the gear ratio and permits both motors to run in their more efficient speed range.

[0056] The present disclosure also contemplates that any of the motors can operate as a generator in response to various conditions in an operating environment. By way of example and not limitation, in the ring subtract mode or a sun subtract mode, one motor is operating in a direction that is opposite to the direction of the other motor and one of the motors is thus removing energy from the rotating system. This energy can flow through the controller and back into a power source to achieve good efficiency. To practice this mode of operation, both motors can be configured to be capable of operating as a generator and, in addition, the controller can be configured to be capable of passing energy from the motors to the power source. In addition, there are modes of operation contemplated by the present disclosure wherein both motors can be operated as a generator to actively apply braking force to the vehicle. In such a case, both motors are generators and supply energy through the controller to the power source.

[0057] Pairs of the exemplary drive systems 10, 110, 210, 310 can be controlled to operate as a differential between the respective wheels. For example, the exemplary drive systems 10 and 110 are interconnected via the shaft 102 and the exemplary drive systems 210 and 310 are interconnected via a shaft 202. The respective second / sun motors and coupled shaft 102 move at the same speed. But the respective first / ring motors can operate at different speeds. This would allow the wheels 92 and 94 to rotate at different speeds when the vehicle 88 is turning.

[0058] In various embodiments of the present disclosure, the two motors can operate in all modes, dynamically switching from one to another based on many factors in the system including torque, speed, remaining battery life, predicted possible failures in one of the two motors or their associated drives, supply voltage level, and thermal state of the motors and drives, to name a few.

[0059] What has been described above includes examples of the subject innovation. It is, of course, not possible to describe every conceivable combination of components or methodologies forAtty Ref: 112540-0009. W01 - 13 -purposes of describing the disclosed subject matter, but many further combinations and permutations of the subject innovation are possible. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to be illustrative and does not pose a limitation on the scope of any innovation disclosed herein unless otherwise claimed. The word “exemplary” is used to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word “exemplary” is intended to present concepts in a concrete fashion. Further, any statements set forth within the Detailed Description of this document and addressing a prior art device(s) are the observations of the inventor and such statements themselves are not prior art or admissions as to what is prior art.

[0060] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Unless indicated otherwise by context, the term “or” is to be understood as an inclusive “or.” Terms such as “first”, “second”, “third”, etc. when used to describe multiple devices or elements, are so used only to convey the relative actions, positioning and / or functions of the separate devices, and do not necessitate either a specific order for such devices or elements, or any specific quantity or ranking of such devices or elements. Use of the terms “about” or “approximately” are intended to cover values that are above and / or below a stated value or range, or within manufacturing tolerances, as would be understood by one having ordinary skill in the art in the respective context. In some instances, this may encompass values in a range of approx. + / -10%; in other instances there may be encompassed values in a range of approx. + / -5%; in yet other instances values in a range of approx. + / -2% may be encompassed; and in yet further instances, this may encompass values in a range of approx. + / -!%.

[0061] It will be 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, unless indicated herein or otherwise clearly contradicted by context. Recitations of a value range herein, unless indicated otherwise, serves as a shorthand for referring individually to each separate value falling within the stated range, including the endpoints of the range, each separate value within the range, and all intermediate ranges subsumed by the overall range, with each incorporated into the specification as if individually recited herein. Unless indicated otherwise, or clearly contradicted by context, methods described herein can be performed with the individual steps executed in any suitable order, including: the precise order disclosed, without any intermediate steps or with one or more further steps interposed between theAtty Ref: 112540-0009. W01 - 14 -disclosed steps; with the disclosed steps performed in an order other than the exact order disclosed; with one or more steps performed simultaneously; and with one or more disclosed steps omitted, unless expressly contradicted by the text herein or context.

[0062] While the present disclosure has been described with reference to one or more exemplary embodiments, it is to be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to a particular embodiment disclosed herein as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will be viewed as covering any embodiment falling within the scope of the appended claims. Various aspects or features described herein may be implemented as a method, apparatus, or article of manufacture using standard programming and / or engineering techniques.

[0063] Also, the right to claim for patent coverage a particular sub-feature, a sub-component, or a sub-element of any disclosed embodiment, singularly or in one or more sub-combinations with any other sub-feature(s), sub-component(s), or sub-el ement(s), is hereby unconditionally reserved by the Applicant. Also, particular sub-feature(s), sub-component(s), and sub-element(s) of one embodiment that is disclosed herein can replace particular sub-features, sub-components, and subelements of another embodiment disclosed herein or can supplement and be added to another embodiment unless expressly indicated otherwise by the drawings or this specification. The inventor also asserts that any of the claims set forth after this detailed description can be combined with any other claim or claims regardless of whether or not there is a direct line of dependency, unless there is an express indication in this text or the drawings unambiguously indicating that such a combination is not possible. The order of the claims and the lines of dependency are irrelevant to the various ways that the features, elements, sub-elements, components, sub-components, etc. of the present disclosure can be combined and thus claimed. Further, the doctrine of claim differentiation is to be applied in construing the appended claims. Further, the use of the word “can” in this document is not an assertion that the subject preceding the word “can” is unimportant or unnecessary or “not critical” relative to anything else in this document. The word “can” is used herein in a positive and affirming sense and no other motive should be presumed. More than one patentable “invention” may be disclosed in the present disclosure and it is noted that an “invention” is defined by the content of a patent claim and not by the content of descriptive text or drawings.Atty Ref: 112540-0009. W01 - 15 -

Claims

CLAIMSWhat is claimed is:

1. A drive system comprising: a first planetary drive set having a first sun member, a first ring member, a first plurality of planet members positioned operably between said first sun member and said first ring member, and a first planet carrier engaged with each of said first plurality of planet members; a first motor having a first stator and a first rotor and centered on a first longitudinal axis; and a second motor having a second stator and a second rotor and centered on said first longitudinal axis and nested within said first motor, wherein said first rotor is fixed for rotation with said first ring member and wherein said second rotor is fixed for rotation with said first sun member.

2. The drive system of claim 1 wherein said first ring member extends along said first longitudinal axis between a first side and a second side, wherein said first side of said first ring member is directed toward said first stator along said first longitudinal axis, wherein said first side is closer to said first stator than said second side along said first longitudinal axis, and wherein a mechanical interconnection between said first rotor and said first ring member does not extend past said second side of said first ring member.

3. The drive system of claim 2 wherein said first rotor is connected to said first side of said first ring member.

4. The drive system of claim 1 wherein said first ring member extends along said first longitudinal axis between a first side and a second side, wherein said second side of said first ring member is directed away from said first stator along said first longitudinal axis, wherein said first side is closer to said first stator than said second side along said first longitudinal axis, wherein said first ring member is positioned between said first planet carrier and said first stator along said first longitudinal axis, and wherein a mechanical interconnection between said first rotor and said firstAtty Ref: 112540-0009. W01 - 16 -ring member does not extend past or overlap said first planet carrier along said first longitudinal axis.

5. The drive system of claim 4 further comprising: an output shaft engaged with said first planet carrier for concurrent rotation, wherein said output shaft is positioned only on said second side of said first ring member along said first longitudinal axis.

6. The drive system of claim 1 wherein said first ring member extends normal to said first longitudinal axis between a radially-inner surface and a radially-outer surface and wherein said first rotor and said first ring member are non-selectively fixed for rotation together.

7. The drive system of claim 1 further comprising: a heat transfer member positioned radially between said first stator and said second stator.

8. The drive system of claim 1 wherein said first stator and said second stator share a plurality of stator laminations, each of said plurality of stator laminations having a first set of stator teeth facing radially outwards and supporting a first winding for driving said first rotor and also having a second set of stator teeth facing radially inwards and supporting a second winding for driving said second rotor.

9. The drive system of claim 1 further comprising: at least one brake selectively engageable with one of said first rotor and said second rotor to selectively inhibit rotation of said one of said first rotor and said second rotor.

10. The drive system of claim 9 wherein said first motor and said second motor are positioned between said first planetary drive set and said at least one brake.Atty Ref: 112540-0009. W01 - 17 -11. The drive system of claim 9 wherein said at least one brake is further defined as: a first brake selectively engageable with said first rotor to selectively inhibit rotation of said first rotor; and a second brake selectively engageable with said second rotor to selectively inhibit rotation of said second rotor.

12. The drive system of claim 1 further comprising: a second planetary drive set having a second sun member, a second ring member, a second plurality of planet members positioned operably between said second sun member and said second ring member, and a second planet carrier engaged with each of said second plurality of planet members; a third motor having a third stator and a third rotor and centered on said first longitudinal axis; and a fourth motor having a fourth stator and a fourth rotor and centered on said first longitudinal axis and nested within said third motor, wherein said third rotor is fixed for rotation with said second ring member and wherein said fourth rotor is fixed for rotation with said second sun member and wherein said second rotor and said fourth rotor are engaged with one another for concurrent rotation.

13. A vehicle comprising: a chassis; a first wheel; and a first drive system positioned on said chassis and having: a first planetary drive set having a first sun member, a first ring member, a first plurality of planet members positioned operably between said first sun member and said first ring member, and a first planet carrier engaged with each of said first plurality of planet members, a first motor having a first stator and a first rotor and centered on a first longitudinal axis, and a second motor having a second stator and a second rotor and centered on said first longitudinal axis and nested within said first motor, wherein said first rotor is fixedAtty Ref: 112540-0009. W01 - 18 -for rotation with said first ring member and wherein said second rotor is fixed for rotation with said first sun member and wherein said first wheel is engaged with said first planet carrier for concurrent rotation.

14. The vehicle of claim 13 further comprising: a second wheel; and a second drive system positioned on said chassis and having: a second planetary drive set having a second sun member, a second ring member, a second plurality of planet members positioned operably between said second sun member and said second ring member, and a second planet carrier engaged with each of said second plurality of planet members; a third motor having a third stator and a third rotor and centered on said first longitudinal axis; and a fourth motor having a fourth stator and a fourth rotor and centered on said first longitudinal axis and nested within said third motor, wherein said third rotor is fixed for rotation with said second ring member and wherein said fourth rotor is fixed for rotation with said second sun member, and wherein said second wheel is engaged with said second planet carrier for concurrent rotation.

15. The drive system of claim 14 wherein said second rotor and said fourth rotor are engaged with one another for concurrent rotation.

16. A method of operating a vehicle having a chassis comprising: driving a first wheel upon which the chassis is supported to thereby move the chassis, said driving including: controlling, with a controller, a first motor, positioned on the chassis and centered on a first longitudinal axis, to rotate a first rotor of the first motor in a first direction at a first speed of rotation, and controlling, with the controller, a second motor, nested in the first motor and positioned on the chassis and centered on the first longitudinal axis, to rotate a second rotor of the second motor in a second direction at a second speed of rotation, wherein the firstAtty Ref: 112540-0009. W01 - 19 -rotor is mechanically coupled to the first wheel through a first ring member of a first planetary drive set positioned on the chassis and the second rotor is mechanically coupled to the first wheel through a first sun member of the first planetary drive set.

17. The method of claim 16 wherein said driving is further defined as driving the wheel at a third speed by said controlling the first motor and said controlling the second motor being further defined such that the first direction and the second direction are the same.

18. The method of claim 17 wherein said driving is further defined as driving the wheel at a fourth speed less than the third speed by: said controlling the first motor is further defined such that the first speed is zero revolutions per minute; and said controlling the second motor is further defined such that the second speed is greater than zero revolutions per minute.

19. The method of claim 16 wherein said driving is further defined as driving the wheel at a fifth speed less than the fourth speed by one of said controlling the first motor is further defined such that the first speed is greater than zero revolutions per minute and said controlling the second motor is further defined such that the second speed is zero revolutions per minute; or said controlling the first motor and said controlling the second motor are further defined such that the first direction and the second direction are opposite to one another.Atty Ref: 112540-0009. W01 - 20 -20. The method of claim 16 further comprising: driving a second wheel upon which the chassis is supported to thereby move the chassis, said driving the second wheel including: controlling, with the controller, a third motor, positioned on the chassis and centered on the first longitudinal axis, to rotate a third rotor of the third motor in a third direction at a third speed of rotation, and controlling, with the controller, a fourth motor, nested in the third motor and positioned on the chassis and centered on the first longitudinal axis, to rotate a fourth rotor of the fourth motor in a fourth direction at a fourth speed of rotation, wherein the third rotor is mechanically coupled to the second wheel through a second ring member of a second planetary drive set positioned on the chassis and the fourth rotor is mechanically coupled to the second wheel through a second sun member of the second planetary drive set; and wherein: said controlling the second motor and said controlling the fourth motor are further defined wherein the second speed and the fourth speed are the same and the second direction and the fourth direction are the same; and said controlling the first motor and said controlling the third motor are further defined wherein the first speed and the third speed are different and the first direction and the third direction are the same.Atty Ref: 112540-0009. W01 - 21 -

Images