Patent ID: 12261510

DETAILED DESCRIPTION OF THE DISCLOSURE

Disclosed herein is a vehicle electric drive assembly having first and second axial flux motors and four driveshafts, namely a main driveshaft, a hollow assist driveshaft, an intermediate driveshaft and an output driveshaft. The main driveshaft is coaxial with the hollow assist driveshaft and extends through the hollow assist driveshaft. The intermediate driveshaft is spaced apart from the main driveshaft and hollow assist driveshaft. The output driveshaft is spaced apart from the intermediate driveshaft. In some embodiments, the output driveshaft may be colinear with the main driveshaft and hollow assist driveshaft. Mounted along the intermediate driveshaft are three gears, namely a first intermediate gear, a second intermediate gear, and a third intermediate gear. A main gear is mounted on the main driveshaft, and the first axial flux motor is coupled to the main driveshaft to drive the main gear. An assist gear is mounted along the hollow assist driveshaft and rotatable relative to the hollow assist driveshaft whereby the assist gear can be engaged and disengaged with the hollow assist driveshaft. The second axial flux motor is coupled to the hollow assist driveshaft and drives the hollow assist driveshaft. Finally, an output gear is mounted on the output driveshaft. The assist gear is permanently meshed with the first intermediate gear of the intermediate driveshaft, the main gear is permanently meshed with the second intermediate gear of the intermediate driveshaft, and the output gear is permanently meshed with the third intermediate gear of the intermediate driveshaft. In one or more embodiments, the electric drive assembly may also include a shift mechanism mounted adjacent the hollow assist driveshaft and actuatable to engage and disengage the assist gear with the hollow assist driveshaft. In a first power mode, the first axial flux motor may drive the main gear, transferring power to the output gear via the second and third intermediate gears. In a second power mode, the first axial flux motor operates as in the first power mode but the assist gear is engaged with the hollow assist driveshaft and driven by the second axial flux motor, thereby transferring power to the output gear via each of the first, second and third intermediate gears. In a third power mode, the first axial flux motor may be allowed to freewheel, utilizing only the second axial flux motor to transfer power to the output gear via the first and third intermediate gears.

With reference toFIG.1a, an electric drive assembly100is provided that that employs two axial flux motors102a,102band a gearing arrangement to mitigate torque interrupt arising. A first axial flux motor102ais coupled to and drives a main or first driveshaft104aextending along a first axis110. A main gear114is disposed along the main driveshaft104a. The main gear114may be integrally formed with the main driveshaft104a, or alternatively, the main gear114may be attached to the main driveshaft104aso as to rotate with the main driveshaft104a. In one or more embodiments, the main gear114is fixed to the main driveshaft104a. In any event, the main driveshaft104ahas a first end106aand a second end106b. In one or more embodiments, main gear114is mounted at the second end106bof the main driveshaft104a, and the first axial flux motor102aengages the first end106aof the main driveshaft104a. As used herein, an axial flux motor refers to an electric device with at least one rotor and corresponding stator spaced apart from one another axially along a driveshaft axis. Such motors typically incorporate magnets that are positioned in planes parallel to the coils. Moreover, as used herein, two-speed refers to a gearbox or transmission with 2 different ratios.

A second axial flux motor102bdrives an assist or second driveshaft104b. In one or more embodiments, the second axial flux motor102bis adjacent the first axial flux motor102a. In any event, assist driveshaft104bhas a first end108aand a second end108bwith an inner bore113passing therethrough between the first end108aand the second end108bsuch that assist driveshaft104bis hollow along the length of assist driveshaft104b. Assist driveshaft104balso has an outer driveshaft surface112. An assist gear116is disposed along the outer driveshaft surface112of the assist driveshaft104b. The assist driveshaft104bis coupled to the second axial flux motor102bat the first end108aof the assist driveshaft104b. The main driveshaft104aextends axially through the assist driveshaft104bso as to be coaxial therewith along first axis110. In one or more embodiments, the assist gear116is mounted along the assist driveshaft104badjacent the outer driveshaft surface112and rotatable relative to the assist driveshaft104b. As such, the assist gear116may freewheel relative to the assist driveshaft104bwhen not coupled to the assist driveshaft104b. In other words, the assist gear116is mounted along the assist driveshaft104bbut rotatable independently of the assist driveshaft104bwhen not coupled thereto by shift mechanism132described below.

In one embodiment, assist gear116may be supported on outer driveshaft surface112of assist driveshaft104bby bearings121that allow assist gear116to freewheel, i.e. rotate independently of assist driveshaft104b. Likewise, bearings121may be affixed within inner bore113of assist driveshaft104bto support main driveshaft104aand allow main driveshaft104ato rotate independently of assist driveshaft104b.

Because the main driveshaft104aand the assist driveshaft104bare coaxial, with the assist driveshaft104bbeing a hollow driveshaft having a through-bore through which the main driveshaft104aextends, the first and second axial flux motors102a,102b, respectively, can be positioned adjacent one another while the two driveshafts104a,104b, respectively, can rotate independently of one another.

Spaced apart from main driveshaft104aand assist driveshaft104bis an intermediate or third driveshaft118that extends along a second axis120. In one or more embodiments, second axis120is parallel with but spaced apart from the first axis110such that intermediate driveshaft118is parallel with main driveshaft104aand assist driveshaft104b. Intermediate driveshaft118has a first end119aand a second end119b.

Positioned along the intermediate driveshaft118is a first intermediate gear122, a second intermediate gear124, and a third intermediate gear126. As shown, in one or more embodiments, first intermediate gear122is mounted adjacent the first end119aof intermediate driveshaft118, third intermediate gear126is mounted adjacent the second end119bof intermediate driveshaft118and second intermediate gear124is mounted on intermediate driveshaft118between first intermediate gear122and third intermediate gear126. In other embodiments, the first intermediate gear122, second intermediate gear124, and third intermediate gear126may be mounted on the intermediate shaft118in another order. For example, in one or more embodiments, the third intermediate gear126may be positioned between the first intermediate gear122and the second intermediate gear124, in which case, output driveshaft128may be spaced apart from each of the first axis110and the second axis120in order to accommodate an output gear130that is permanently meshed with the third intermediate gear126.

As shown inFIG.1a, first intermediate gear122is permanently meshed with the assist gear116so that the first intermediate gear122and the assist gear116are in constant engagement with one another. Likewise, second intermediate gear124is permanently meshed with main gear114so that the second intermediate gear124and the main gear114are in constant engagement with one another.

Electric drive assembly100also includes an output or fourth driveshaft128. As shown inFIG.1a, output driveshaft128is radially spaced apart from intermediate driveshaft118. In one or more embodiments, output driveshaft128may extend along first axis110so as to be colinear with main driveshaft104aand assist driveshaft104b, but in such case, output driveshaft128is axially spaced apart from main driveshaft104aand assist driveshaft104b. In other embodiments, output driveshaft128may extend along a third axis (not shown) separate from first axis110and second axis120. In any event, output driveshaft128has a first end129aand a second end129bwith an output gear130mounted on the output driveshaft128between the two ends129a,129b, and coupled to the third intermediate gear126carried by intermediate driveshaft118. More specifically, output gear130is permanently meshed with third intermediate gear126so that the third intermediate gear126and the output gear130are in constant engagement with one another. In one embodiment, output gear130is mounted adjacent the first end129aof output driveshaft128and a drive flange135is mounted adjacent the second end129bof output driveshaft128.

As used herein, “permanently meshed” means that two gears are in constant engagement or continuously meshed with one another during operation of electric drive assembly100. In this regard, all intermediate gears described herein, namely first intermediate gear122, second intermediate gear124and third intermediate gear126are permanently meshed with their respective gears simultaneously during operation of electric drive assembly100. It should be noted that because the various gears are in constant engagement as described herein, the axial and radial spacing between the various driveshafts, namely the first driveshaft104a, the second driveshaft104b, the third driveshaft118and the fourth driveshaft128, may be fixed. In other words, all of the driveshafts may be axially and radially fixed relative to one another, thereby minimizing the size of a gearbox housing133disposed to encase the gears and driveshafts. Specifically shown inFIG.1ais first driveshaft104aand second driveshaft104bextending through gearbox housing133so that first and second axial flux motors102a,102bare external of gearbox housing133. Likewise, fourth driveshaft128extends through gearbox housing133so that drive flange135is also external of gearbox housing133.

In the illustrated embodiment, main gear114has a first radius R1; assist gear116has a second radius R2; first intermediate gear122has a third radius R3; second intermediate gear124has a fourth radius R4; third intermediate gear126has a fifth radius R5; and output gear130has a sixth radius R6. It will be appreciated that the various radii of the gears may be selected to achieve a particular gearing ratio, and the disclosure in not limited to particular gearing ratios. However, in some embodiments, R3 is greater than R4, which is greater than R5 and R6 is greater than R1 which is greater than R2.

In the embodiment ofFIG.1a, gears114,116,122,124,126and130are generally depicted as spur gears, but may be other types of gears as well, such as, but not limited to helical gears. In one or more embodiments, output gear130, main gear114and first intermediate gear122are bull gears, being larger in diameter than the gears to which each is continuously meshed.

It will be appreciated that so long as the various gears are permanently meshed and transfer power as described herein, the specific physical arrangement of the gears and driveshafts relative to one another is not limited by this disclosure. For example, the output driveshaft128may be positioned along a different axis than the first axis110. Moreover, the output driveshaft128may be adjacent the axial flux motors102, in which case, the third intermediate gear126may be positioned at the first end119aof intermediate driveshaft118with second intermediate gear124positioned at the second end119bof intermediate driveshaft118. Similarly, while the gears depicted herein are shown as spur gears and the various driveshafts are parallel to one another, in other embodiments, the gears may be other types of gears so that the driveshafts may be angled relative to one another. For example, third intermediate gear126may be a bevel gear and output gear130may be bevel gear such that output driveshaft128is perpendicular to intermediate driveshaft118. Finally, unlike the prior art, with these fixed components, neither gears nor driveshaft are “shifted” in the sense of being physically moved to change gears. Rather, the electric drive assembly100experiences a gear transition between torque mode and power mode utilizing the described gearing arrangement.

Electric drive assembly100also includes a shift mechanism132disposed to at least couple and decouple assist gear116with assist driveshaft104b. Although not limited to a particular mechanism or device, in one or more embodiments, shift mechanism132may include cooperating elements137that engage with cooperating elements on assist gear116. In some embodiments, shift mechanism132may include an axially slidable dog ring or shift sleeve132b(seeFIG.4). In one or more embodiments, shift mechanism132is adjacent assist gear116. In this regard, shift mechanism132may be disposed along first axis110and positioned between the main gear114and the assist gear116in order to at least couple the assist gear116to the assist driveshaft104bas desired. For example, shift mechanism132may be mounted on assist driveshaft104band coupled thereto so that rotation of the assist driveshaft104brotates the shift mechanism132. In any event, shift mechanism132may be disposed to engage and disengage the assist gear116in order to couple and decouple the assist gear116and the assist driveshaft104b, respectively. In other embodiments, shift mechanism132may be disposed to alternately engage either the assist gear116or the main gear114. Where shift mechanism132is disposed to engage either assist gear116or main gear114, the shift mechanism132can be moved to work together with the main gear114for increased speed or with assist gear116for increased torque from electric drive assembly100.

As shown inFIG.1a, an actuator142may be utilized to move shift mechanism132to engage and disengage gears as desired. In some embodiments, shift mechanism132may include a linkage140that urges shift mechanism132between engaged and disengaged positions. In one or more embodiments, actuator142is an electric actuator mechanism.

Shift mechanism132may be utilized to allow second axial flux motor102bto be utilized in conjunction with first axial flux motor102a, or vice versa, without resulting in torque interrupt. In one illustrative example, first axial flux motor102adrives main gear114, which in turn rotates intermediate second driveshaft118via second intermediate gear124with which main gear114is continuously meshed. The rotating intermediate second driveshaft118drives first intermediate gear122which is continuously meshed with assist gear116mounted about assist driveshaft104b. Notably, assist gear116is mounted about assist driveshaft104bso as to spin freely or independently thereof when not coupled to assist driveshaft104bby shift mechanism132. For example, first axial flux motor102amay operate at a select first speed RPM1that results in rotation of assist gear116at an assist gear speed RMPa. Second axial flux motor102bneed not be in operation while first axial flux motor102ais in operation. In order to allow second axial flux motor102bto be utilized in conjunction with first axial flux motor102a, second axial flux motor102bis utilized to rotate assist driveshaft104band thereby rotate shift mechanism132affixed to assist driveshaft104b. The second motor102bis operated at a second speed RPM2selected so that shift mechanism132rotates at the same speed as assist gear speed RMPa. In other words, first and second axial flux motors102a,102bare operated at speeds that allow the rotational speed of the shift mechanism132to match or otherwise be synchronized with the rotation speed RMPaof the assist gear116, at which point, the shift mechanism132may be actuated so that shift mechanism132engages assist gear116, thereby coupling assist gear116to assist driveshaft104b. Thereafter, second axial flux motor102bcan be utilized to provide additional torque to output driveshaft128, or alternatively, first and second axial flux motors102a,102bcan be adjusted to achieve a desired torque-speed output for electric drive assembly100. This arrangement allows second axial flux motor102bto be engaged to assist in driving output driveshaft128without any torque interrupt, and specifically, without the need to disengage any gears. Thus, power can be maintained during the entire process.

To assist in matching speeds as described above, one or more speed sensors146may be disposed adjacent at least one of the driveshafts or gears to monitor the rotational speed of the driveshaft and/or gears. In the illustrated embodiment, a speed sensor146ais shown adjacent assist driveshaft104b, a speed sensor146bis shown adjacent intermediate driveshaft118, a speed sensor146cis shown adjacent output driveshaft128and a speed sensor146dis shown adjacent main driveshaft104a. Persons of skill in the art will appreciate that such speed sensors146may be positioned to measure the rotational speed of a driveshaft or of a gear mounted on the driveshaft. Moreover, while four speed sensors146are shown for some embodiments, in other embodiments, only two sensors146need be utilized to measure the relative RPMs resulting from the first and second axial flux motors102a,102b. Alternatively, without the need for speed sensors146at all, the speed of the second axial flux motor102bmay be adjusted based on the known speed of the first axial flux motor102aand the known geometry of the various shafts and gears.

In one or more other embodiments as shown inFIG.1B, rather than utilizing assist gear116on assist driveshaft104bas the “freewheel” gear, and continuously engaging fixed first intermediate gear122mounted on the intermediate driveshaft118, the relative positions of these two meshed gears may be reversed. Specifically, assist gear116may be a fixed gear mounted on assist driveshaft104band first intermediate gear122may be a freewheel gear disposed about intermediate driveshaft118. In such case, first intermediate gear122rotates about second axis120independently of intermediate driveshaft118. It will be appreciated that in this embodiment, shift mechanism132is positioned adjacent first intermediate gear122in order to couple and decouple first intermediate gear122with intermediate driveshaft118. In this regard, shift mechanism132may move axially along second axis120. Bearings121may be utilized between first intermediate gear122and intermediate driveshaft118to allow independent rotation of first intermediate gear122relative to intermediate driveshaft118.

In one or more other embodiments as shown inFIG.1c, rather than utilizing assist gear116on assist driveshaft104bas the “freewheel” gear, assist gear116may be a fixed gear mounted on assist driveshaft104band main gear114disposed about main driveshaft104amay be utilized as the freewheel gear. In such case, main gear114rotates about first axis110independently of main driveshaft104a. It will be appreciated that in this embodiment, shift mechanism132is positioned adjacent main gear114in order to couple and decouple main gear114with main driveshaft104a. Bearings121may be utilized between main gear114and main driveshaft104ato allow independent rotation of main gear114relative to main driveshaft104a.

In one or more other embodiments as shown inFIG.1d, rather than utilizing main gear114on main driveshaft104aas the “freewheel” gear that continuously meshes with a fixed gear124mounted on intermediate driveshaft118, the relative positions of these two meshed gears may be reversed. Specifically, main gear114may be a fixed gear mounted on main driveshaft104aand second intermediate gear124may be a freewheel gear disposed about intermediate driveshaft118. In such case, second intermediate gear124rotates about second axis120independently of intermediate driveshaft118. It will be appreciated that in this embodiment, shift mechanism132is positioned adjacent second intermediate gear124in order to couple and decouple second intermediate gear124with intermediate driveshaft118. In this regard, shift mechanism132may move axially along second axis120. Bearings121may be utilized between second intermediate gear124and intermediate driveshaft118to allow independent rotation of second intermediate gear124relative to intermediate driveshaft118.

Thus, based on the foregoing, the various embodiments generally include four optional positions for the freewheel gear and two optional positions for the shift mechanism132. In this regard, the electric drive assembly100can be said to include a main driveshaft104a, an assist driveshaft104b, an intermediate driveshaft118and an output driveshaft128. A main gear114is disposed along the main driveshaft104a; an assist gear116is disposed along the assist driveshaft104b; first, second and third intermediate gears122,124,126, respectively, are disposed along the intermediate driveshaft118and spaced apart from one another; and an output gear130is affixed to the output driveshaft128. The main gear114is continuously meshed with the second intermediate gear124; the assist gear116is continuously meshed with the first intermediate gear122; and the output gear130is continuously meshed with the third intermediate gear126which third intermediate gear is fixed to the intermediate driveshaft118. One of the main gear114, assist gear116, first intermediate gear122or second intermediate gear124is a freewheel gear disposed to be rotatable independently from the driveshaft about which it is mounted. A shift mechanism is disposed adjacent this freewheel gear and axially movable to couple and decouple the freewheel gear and the driveshaft about which it is mounted.

Turning toFIG.2, another embodiment of electric drive assembly100is shown. In the illustrated embodiment, an assist gear116is disposed around assist driveshaft104b. Although axially constrained along assist driveshaft104b, assist gear116is not affixed to assist driveshaft104b, but rather is disposed to rotated independently of assist driveshaft104b. Assist driveshaft104bmay be supported by bearings121mounted on a first side115of the gearbox housing133and a first support plate131amounted within the gearbox housing133and spaced apart from first side115. Assist driveshaft104bextends through the gearbox housing133and is driven my second axial flux motor102b. Shift mechanism132is shown adjacent assist gear116so as to permit selective engagement of shift mechanism132with assist gear116upon actuation of shift mechanism132.

A main driveshaft104ais shown extending through second axial flux motor102band assist driveshaft104b. First axial flux motor102adrives main driveshaft104a. Affixed to main driveshaft104a(or integrally formed therewith) is a main gear114such that rotation of main driveshaft104aby first axial flux motor102ain turn drives main gear114. In the illustrated embodiment, main driveshaft104aextends fully through assist driveshaft104band protrudes therefrom so that main driveshaft104acan be supported by bearings121carried on a second support plate131bmounted within the gearbox housing133and positioned between first support plate131aand a second side117of gearbox housing133. Although main gear114is shown mounted on main driveshaft104aso that main gear114is positioned between second support plate131band second side117, main gear114may be mounted on main driveshaft104aon the opposite side of second support plat131bso that main gear114is positioned between the first support plate131aand the second support plate131b.

In the illustrated embodiment, second intermediate gear124is carried on intermediate driveshaft118and is continuously meshed with main gear114. Intermediate driveshaft118may be mounted on bearings121carried by first side115of gearbox housing133, second side117of gearbox housing133, and in some embodiments, by one or both support plates131a,131b, or any combination thereof.

Also mounted on intermediate driveshaft118is a first intermediate gear122that is continuously meshed with the assist gear116disposed around assist driveshaft104b.

Finally, an output driveshaft128is shown supported between the second side117of gearbox housing133and the second support plate131b. While output driveshaft128may also be supported by bearings121on second support plate131b, it should be noted that output driveshaft128is spaced apart and separate from main driveshaft104a. In any event, an output gear130is mounted on output driveshaft128and continuously meshed with third intermediate gear126carried on intermediate driveshaft118.

A shift mechanism132is shown mounted adjacent assist gear116. Shift mechanism132may be actuatable to selectively engage and disengage assist gear116with assist driveshaft104b. When assist gear116is engaged with assist driveshaft104bby shift mechanism132, power from second axial flux motor102bmay be transferred to intermediate driveshaft118to assist with power from first axial flux motor102atransferred to intermediate driveshaft118by main gear114. It will be appreciated that in one or more embodiments where R3>R4>R5 and R6>R1>R2 the power from second axil flux motor102bmay be utilized to increase output torque by output driveshaft128. Moreover, when speed of output driveshaft130is desired over torque, shift mechanism132may be actuatable to disengage assist gear116from assist driveshaft104bso that only first axial flux motor102ais driving output driveshaft128.

One or more speed sensors146may be utilized to measure the timing of the driveshafts and or gears to so that the RPMs of one or both axial flux motors may be adjusted in order to facilitate engagement of assist gear116with assist driveshaft104bby shift mechanism132. AlthoughFIG.2illustrates speed sensors146b,146cand146d, the disclosure is not limited to a particular number of speed sensors146or their placement unless otherwise specifically noted.

FIG.3is similar toFIG.2, but with axial flux motors102a,102band gearbox housing133removed in order to better illustrate additional components of embodiment of electric drive assembly100. For example, although not required, in some embodiments, shift mechanism132may be driven by an actuator142(also shown inFIG.1a). In some embodiments, actuator142may be an electric actuator142to urge shift mechanism132between positions, which positions include at least a first “neutral” position in which shift mechanism132is not engaged with a gear, and a second position in which shift mechanism132engages a freewheel gear, such as assist gear116, in order to couple the freewheel gear to a driveshaft, such as assist driveshaft104b. Some embodiments may include a third position in which shift mechanism140engages the main gear114in order to couple main gear114to assist driveshaft104bin an alternative arrangement for utilizing both first and second axial flux motors102a,102bas a source of power for output driveshaft128.

InFIG.3, a speed sensor146bis mounted adjacent the intermediate driveshaft118to monitor rotation of the intermediate driveshaft118and a speed sensor146cis positioned adjacent the output driveshaft128to monitor rotation of the output driveshaft128.

In the embodiments show inFIGS.2and3, gears114,116,122,124,126and130are shown as helical gears, but may in other embodiments, different types of gears may be utilized.

With reference back toFIG.1aand reference toFIG.4, while shift mechanism132is not limited to a particular configuration, one embodiments of shift mechanism132is shown in theFIG.4. In this embodiment, shift mechanism132utilizes cooperating elements, such as cooperating elements136aand137shown inFIG.4, to engage one another. In particular, shift mechanism132includes a fixed hub134that is attached to assist driveshaft104b(seeFIG.1a) so as to rotate with assist driveshaft104b. The illustrated shift mechanism132also includes with a dog ring or shift sleeve136that is slidingly engaged with fixed hub134. Shift sleeve136is axially movable relative to fixed hub134. In one or more embodiments, shift sleeve136includes one or more cooperating elements136athat engage with one or more cooperating elements134aof fixed hub134in order to constrain shift sleeve136to axial movement along first axis110. In some embodiments, these cooperating elements may be teeth. In the illustrated embodiment, cooperating elements134aare formed about an exterior perimeter of fixed hub134and cooperating elements136aare formed about an interior perimeter of shift sleeve136.

In addition, the cooperating elements136aof shift sleeve136may function as engagement mechanisms to allow shift sleeve136to couple with an adjacent gear, such as assist gear116described inFIG.1aand illustrated inFIG.4. To facilitate such coupling, the adjacent gear may also include one or more cooperating elements137that can be engaged by the cooperating elements136aof shift sleeve136. In such case, cooperating elements136amay engage both the cooperating elements134aof fixed hub134as well as the cooperating elements137of assist gear116. In some embodiments, cooperating elements136amay allow shift sleeve136to couple to main gear114when disengaged from assist gear116. In such case, main gear114would likewise include cooperating elements137formed thereon. Similarly, rather than utilizing cooperating elements136aformed about an interior perimeter of shift sleeve136, cooperating elements137may be formed on one or both end faces136bof shift sleeve136for engagement with cooperating elements137of a gear.

In other embodiments, shift sleeve136may include one or more first cooperating elements136adisposed to engage and disengaged with assist gear116and one or more second cooperating elements136adisposed to engage and disengaged with a main gear114. In such case, cooperating elements136amay be provided on each opposing end face136bof shift sleeve136. In any event, cooperating elements as described herein may include extensions, teeth, knobs, recesses, protrusions or the like so long as the cooperating elements engage one another. For example, teeth may engage teeth or protrusion may engage a recess. In one or more embodiments, the cooperating elements137on a gear may be disposed about a periphery or face of a gear, such as is shown on the end face116aof assist gear116inFIG.4. In the illustrated embodiment, cooperating elements137extend axially away from end face116aof assist gear116towards shift mechanism132. Rather than or in addition to cooperating elements around an interior perimeter of shift sleeve136to engage an adjacent gear, cooperating elements136amay be formed on one or both opposing end face136bof shift sleeve136.

Notably, in the above-described configuration of electric drive assembly100, the first and second axial flux motors102a,102bcan be utilized to synchronize the rotational speeds of the assist gear116with the assist driveshaft104b, eliminating the need for a traditional synchronizer ring or blocker ring of the prior art, as well as the need for a friction cone on the gear as is commonly utilized in the prior art for coupling. In the electric drive assembly100, once the rotational speed of freewheel gear, such as the assist gear116, and driveshaft about which it is disposed, such as the assist driveshaft104b, have been synchronized through control of the axial flux motors102a,102b, shift sleeve136may be engaged with assist gear116via cooperating elements136aand cooperating elements137, respectively. Additionally, in some embodiments, main gear114may also include one or more cooperating elements137formed on the main gear114for engagement by the cooperating elements136aof shift sleeve136when disengaged with assist gear116, thereby allowing second axial flux motor102bto assist in driving main gear114. The foregoing eliminates the need for friction cones as is common in the prior art. It will be appreciated that by eliminating the need for traditional synchronizer rings and friction cones, the axial length and the relative weight of electric drive assembly100may also be reduced.

In one or more embodiments, the shift mechanism132is axially movable along assist driveshaft104ballowing the output from the second axial flux motor102bto be directed to the output driveshaft128through the main gear114and through the assist gear116. In some embodiments, a linkage140, such as a shift fork, may be utilized by shift mechanism132to move the shift mechanism132between a first position in which the shift mechanism132is engaged with one gear, a second position in which the shift mechanism132is disengaged from any gears and a third position in which the shift mechanism132is engaged with another gear. In such embodiments, at least one of the gears is a freewheel gear as described and generally depicted by assist gear116inFIG.1a.

To optimize engagement of the coopering elements136aof shift mechanism132with the cooperating elements137of assist gear116, one or more speed sensors146may be disposed adjacent at least one of the shafts or gears to monitor the rotational speed of the driveshaft and/or gears. Because the position of the speed sensor146relative to an engagement mechanism can be fixed, the shift mechanism can be shifted into full engagement without utilizing synchronizer systems of the prior art.

Referring back toFIG.1a, in one or more embodiments, a single inverter144may be electrically coupled to each of the first and second axial flux motors102a,102band the electric actuator142to reduce latency. In such case, the speed sensor(s)146may operate in collaboration with a single controller148controlling each of the first and second axial flux motors102a,102band the electric actuator142. Because a single inverter144can be utilized for both axial flux motors102a,102b, the need for a telematic control unit (“TCU”), which would otherwise be required to communicate with separate electrical components such as multiple inverters, as is common in the prior art, can be eliminated, thereby improving latency in the operation of the electric drive assembly100.

It will be appreciated that the gearing ratios are flexible and may be selected for each of the gears to achieve desired results. In any event, since the main gear114is always engaged and driven by the first axial flux motor102a, there is not a drop off or torque interrupt as the shift mechanism132is shifted to utilize output from the second axial flux motor102b, whether through the main gear114or through the assist gear116. It is the two separate axial flux motors102a,102b, along with the described constantly engaged gearing mechanisms, that permit torque interrupt to be mitigated as described. In any event, because the main gear114is always engaged and driving when first axial flux motor102ais in operation, there is no drop-off in speed of the main gear114as the shift mechanism132is shifted to engage or disengage the assist gear116.

In one or more embodiments, a speed sensor146bis mounted adjacent the intermediate driveshaft118to monitor rotation of the intermediate driveshaft118. It will be appreciated that the shift mechanism132, and in particular, shift sleeve136, may include one or more engagement mechanisms or cooperating elements, such as teeth, extensions, knobs, recesses, protrusions or the like, that are disposed to couple with corresponding cooperating elements on the assist gear116and, in some embodiments, also on the main gear114. By knowing the rotational speed of intermediate driveshaft118, the gears116,114can be fully engaged without torque interrupt or the need for any intermediate friction coupling utilizing friction cones. This synchronization is derived from the one or more of the speed sensors146. Once the overall electric drive assembly100is assembled, the relative relationship or positions between main gear, the assist gear, the intermediate gears, and the output gear are fixed and do not change over time. Knowing the rotational speed of the intermediate driveshaft (or another component of the main, intermediate or output systems), therefore, permits the speed of the second axial flux motor102bto be adjusted accordingly to synchronize engagement of the shift mechanism132with either of the main gear114or the assist gear116.

Turning to another novel aspect of above-described electric drive assembly100, the presence of two axial flux motors102a,102bpermits one of the axial flux motors102to be utilized for electricity generation when the electric drive assembly100is switches from a speed mode to a torque mode. Specifically, it will be appreciated that at times, a particular gearing ratio may be desired only utilizing the assist gear116. In such case, because main gear114is always engaged with second intermediate gear124such that main driveshaft104ais always in motion, first axial flux motor102adriven by main driveshaft104acan be utilized in a regeneration mode to generate electricity as an alternator, much in the same way rotational speed/torque bled off through either driveshaft104could be used to drive an axial flux motor102to generate electricity. In one or more embodiments where electricity is generated from one of the axial flux motors102a,102b, inverter144may also be utilized to manage the generated electricity. It will be appreciated that the larger the electrical pulse resulting from regeneration (which may occur when transitioning from high-speed mode utilizing first axial flux motor102ato high torque mode utilizing second axial flux motor102b), the longer period of time that is required in order to dampen or bleed off the electricity generated from axial flux motor102a. Moreover, the larger the pulse, the greater the amount of heat that may be managed by the inverter144, which may be necessary to avoid overheating of various electrical components. Thus, there is a desire to minimize the regeneration mode of the axial flux motors during a gear transition between torque and power modes of electric drive assembly100.

Turning toFIG.5, to minimize regeneration from axial flux motors102during a gear transition between torque and power modes, in one or more embodiments, one or both axial flux motors102include rotor assemblies with non-magnetic components that are constructed primarily of non-conducting materials, such as composite or polymers in order to reduce weight of the rotor assemblies. Such construction minimizes the energy pulse dampening of the motors before synchronization as described above. Thus, for example, referring toFIG.5, there is shown an axial flux type electric motor assembly200. Electric motor assembly200includes at least one rotor assembly210and at least one stator assembly212disposed axially from one another along a motor axis214. In the illustrated embodiment, a rotor spindle or driveshaft216extends along axis214and supports rotor assembly210. Rotor driveshaft216may include a spindle flange217that attaches to rotor assembly210. Rotor driveshaft216may in turn be supported by one or more bearings218.

Although only a single stator assembly212may be utilized, in the illustrated embodiment, two stator assemblies212a,212bare shown and positioned on opposing sides of single rotor assembly210along axis214. It will be appreciated that by minimizing the number of rotor assemblies, the overall weight of axial flux motor200, particularly as used in electric drive assembly100, may be minimized to minimizes the need for energy pulse dampening when alternating between speed mode and torque mode as described above. In this regard, the gearing arrangement of electric drive assembly100as described herein is particularly suited for a pair of single rotor axial flux motors as described in some embodiments because each of the axial flux motors may be utilized as needed to achieve a desired output without while limiting the potential energy pulse that could result from rotors with larger mass and inertia.

A motor housing220and opposing stator support or end plates222enclose rotor assembly210and the one or more stator assemblies212. In one or more embodiments, at least one end plate222supports a stator assembly212on an interior surface223of the end plate222. In the illustrated embodiment, end plate222asupports stator assembly212aand end plate222bsupports stator assembly212b.

To the extent an end plate222supports a stator assembly212, the end plate222may include cooling a cooling mechanism224positioned along the exterior surface226of the end plate222.

In one or more embodiments, cooling mechanism224may form one or more coolant flow paths228along the exterior surface226of end plate222. Coolant flow path228may be one or more cooling channels230formed in the exterior surface226of end plate222.

In the illustrated embodiment, a plurality of fluidically connected cooling channels230are illustrated and are generally positioned to extend around the end plate222opposite the stator assembly212mounted on the interior surface223of end plate222. Although not limited to a particular configuration, in one embodiment, cooling channels230may form star shape along the exterior surface226to maximize cooling while allowing fasteners227to secure various motor components to end plate222from the interior surface223without extending through end plate222to the exterior surface226of end plate222. In other words, threaded bores for engagement by fasteners227may be formed on the interior surface223of end plate222, but the bores do not extend all the way through end plate222. It will be appreciated that such an arrangement minimizes the likelihood that fluid within the interior of motor assembly200could leak or migrate out or that vice-versa. In other embodiments, coolant flow path228may be formed of tubing (not shown) positioned on the exterior surface226. In yet other embodiments, coolant flow path228may be formed of ribs or fins (now shown) extending from exterior surface228, while in other embodiments, coolant flow path228may simply be a coolant chamber formed between end plate222and an outer plate234. Notwithstanding the foregoing, it will be appreciated that cooling channels230formed in the exterior surface226of end plate222may be particularly desirable to minimize the overall axial length of electric motor assembly200. In any event, one or more ports225in fluid communication with flow path228may be utilized to introduce and extracted coolant from the from cooling mechanism224.

Each stator assembly212is generally formed of a stator core238and stator windings240as may be known to persons of skill in the art. In this regard, stator windings240may be formed of electric wire. The disclosure is not limited to a particular configuration for stator assembly212.

With reference toFIGS.6and7and ongoing reference toFIG.5, rotor assembly210is generally formed of a rotor core or yoke242disposed to carry a plurality of magnets244. In one or more embodiments, rotor core242is spider shaped and formed of a hub246from which fingers248radially extend. Fingers248are spaced apart from one another around the perimeter of hub246so as to form magnet pockets250between adjacent fingers248. In one or more embodiments, rotor assembly210further includes a rotor ring252disposed radially outward from fingers248. In one or more embodiments, rotor ring252and rotor core242may be separate components, such as is shown inFIGS.1,2A and2B, while in other embodiments, rotor ring252and rotor core242may be integrally formed.

In one or more embodiments, rotor core242is formed of a non-conducting composite material. Similarly, in one or more embodiments, rotor ring252is formed of a non-conducting composite material.

Turning toFIGS.6-7, embodiments of a rotor assembly210are shown and generally described as rotor assembly310. Rotor assembly310generally includes a rotor core or yoke342disposed to carry a plurality of magnets344. In one or more embodiments, rotor core342is spider shaped and formed of a hub346from which fingers348radially extend. Fingers348are spaced apart from one another around the perimeter of hub346so as to form magnet pockets350between adjacent fingers348. Rotor assembly further includes a rotor ring352disposed radially outward from fingers348. Although not limited to a particular number of fingers348and pockets350, in the illustrated embodiment, rotor core342includes ten fingers348and ten magnet pockets350.

In the illustrated embodiment of rotor assembly310, fingers348are generally rectangular in shape so that magnet pockets350are generally wedge shaped.

As such, in this illustrated embodiment, magnets344are generally wedge shaped, where each magnet344has a radially outer edge360of a greater length than a radially inner edge362which edges360,362are joined by side edges364. In one or more embodiments, as best seen inFIG.8B, at least one and preferably each side edge364of a magnet344includes a groove or slot366extending along at least a portion of the length of side edge364between radially outer edge360and radially inner edge362. In one or more embodiments, each groove366fully extends between radially outer edge360and radially inner edge362, while in other embodiments groove366extends from radially outer edge360and is spaced apart from radially inner edge362. In yet other embodiments, groove366is spaced apart from radially outer edge360and extends from radially inner edge362. Finally in other embodiments, groove366is formed alongside edge364to be spaced apart from both radially outer edge360and radially inner edge362.

Similarly, each finger348of hub346has a side edge368that extends from a proximal end369aadjacent the hub346to a distal end369bat the periphery of the rotor core342. In one or more embodiments, the side edges368of each finger may be generally smooth without any feature formed therealong. In one or more other embodiments, each side edge368of a finger348includes a groove or slot370extending along at least a portion of the length of side edge368between the proximal end369aand the distal end369bof finger348.

In one or more embodiments, each groove370fully extends between the proximal end369aand the distal end369bof finger348, while in other embodiments groove370extends from distal end369band is spaced apart from proximal end369a. In yet other embodiments, groove370is spaced apart from distal end369band extends from proximal end369a. Finally in other embodiments, groove370is formed alongside edge368to be spaced apart from both the distal end369band the proximal end369aof finger348.

In one or more embodiments, rotor ring352is a pre-formed ring that is positioned around rotor core342. In some embodiments, rotor ring352is a continuous, solid ring. In this regard, rotor ring352may be formed of a composite material, such as a fiber material. Rotor ring352has a radially inner edge376and a radially outer edge378, where radially inner edge376may abut fingers348when positioned around rotor core342. In one or more embodiments, the radially inner edge376of solid, pre-formed rotor ring352is formed. As will be appreciated, each of the carbon fiber material and glass fiber material may be formed of a substrate on which the fibers are carried.

Turning toFIG.8, in one or more embodiments, rotor core or yoke342may be formed of a multiplicity of layers380of fiber material arranged in a stack382or “book” as shown. Each fiber layer380may be a material having a set of primary fibers. Individual layers280are formed into the stack282.

Thus, an electric drive assembly has been described. In one or more embodiments, the electric drive assembly includes a first axial flux motor; a main driveshaft with a first end and a second end, the main driveshaft disposed along a first axis and coupled to the first axial flux motor; a second axial flux motor positioned adjacent the first axial flux motor; an assist driveshaft with a first end and a second end, wherein the assist driveshaft is hollow with an outer driveshaft surface and an inner bore passing therethrough between the first and second ends of the assist driveshaft, the assist driveshaft coupled to the second axial flux motor, wherein the main driveshaft passes through the assist driveshaft so as to be coaxial therewith; a main gear fixed to the main driveshaft; an assist gear mounted along the assist driveshaft and rotatable relative to the assist driveshaft; an intermediate driveshaft extending along a second axis, the intermediate driveshaft parallel with but spaced apart from the first axis; a first intermediate gear mounted on the intermediate driveshaft and continuously meshed with the assist gear; a second intermediate gear mounted on the intermediate driveshaft and continuously meshed with the main gear; a third intermediate gear mounted on the intermediate driveshaft; an output driveshaft disposed along the first axis but spaced apart from the first and second drive shafts; an output gear fixed to the output driveshaft and continuously meshed with the third intermediate gear; and a shift mechanism mounted along the assist driveshaft and axially movable along the assist driveshaft between the main gear and the assist gear. In one or more other embodiments, the electric drive assembly may include a first axial flux motor; a main driveshaft with a first end and a second end, the main driveshaft disposed along a first axis and coupled to the first axial flux motor; a second axial flux motor positioned adjacent the first axial flux motor; an assist driveshaft with a first end and a second end, wherein the assist driveshaft has an inner bore passing therethrough between the first and second ends of the assist driveshaft and an outer driveshaft surface on which a guide mechanism150is formed, the assist driveshaft coupled to the second axial flux motor, wherein the main driveshaft passes through the assist driveshaft so as to be coaxial therewith; a main gear fixed to the main driveshaft, the main gear including a first face and an opposing second face and an outer peripheral surface along which radially extending teeth are formed, with a first axial engagement mechanism formed on the first face adjacent the outer peripheral surface of the main gear; an assist gear mounted along the assist driveshaft and rotatable relative to the outer driveshaft surface of the assist driveshaft, the assist gear including a first face and an opposing second face and an outer peripheral surface along which radially extending teeth are formed, with a second axial engagement mechanism formed on the second face adjacent the outer peripheral surface of the assist gear; an intermediate driveshaft extending along a second axis, the intermediate driveshaft parallel with but spaced apart from the first axis; a first intermediate gear mounted on the intermediate driveshaft and continuously meshed with the assist gear; a second intermediate gear mounted on the intermediate driveshaft and continuously meshed with the main gear; a third intermediate gear mounted on the intermediate driveshaft; an output driveshaft disposed along the first axis but spaced apart from the first and second drive shafts; an output gear fixed to the output driveshaft and continuously meshed with the third intermediate gear; and a dog ring coupled to the assist driveshaft and axially movable along the assist driveshaft between the main gear and the assist gear, wherein the dog ring has a central aperture with a radially extending notch that engages the guide mechanism of the assist driveshaft, and an engagement mechanism disposed to couple with one of the first axial engagement mechanism or the second axial engagement mechanism. In one or more other embodiments, the electric drive assembly may include a first axial flux motor comprising a single, non-metallic rotor; a main driveshaft with a first end and a second end, the main driveshaft disposed along a first axis and coupled to the first axial flux motor; a second axial flux motor positioned adjacent the first axial flux motor, the second axial flux motor comprising a single, non-metallic rotor; an assist driveshaft with a first end and a second end, wherein the assist driveshaft has an inner bore passing therethrough between the first and second ends of the assist driveshaft and an outer driveshaft surface, the assist driveshaft coupled to the second axial flux motor, wherein the main driveshaft passes through the assist driveshaft so as to be coaxial therewith; a main gear fixed to the main driveshaft, the main gear including a first face and an opposing second face and an outer peripheral surface along which radially extending teeth are formed, with a first axial engagement mechanism formed on the first face adjacent the outer peripheral surface of the main gear; an assist gear mounted along the assist driveshaft and rotatable relative to the outer driveshaft surface of the assist driveshaft, the assist gear including a first face and an opposing second face and an outer peripheral surface along which radially extending teeth are formed, with a second axial engagement mechanism formed on the second face adjacent the outer peripheral surface of the assist gear; an intermediate driveshaft extending along a second axis, the intermediate driveshaft parallel with but spaced apart from the first axis; a first intermediate gear mounted on the intermediate driveshaft and continuously meshed with the assist gear; a second intermediate gear mounted on the intermediate driveshaft and continuously meshed with the main gear; a third intermediate gear mounted on the intermediate driveshaft; an output driveshaft disposed along the first axis but spaced apart from the first and second drive shafts; an output gear fixed to the output driveshaft and continuously meshed with the third intermediate gear; a dog ring slidingly coupled to the assist driveshaft and axially movable along the assist driveshaft between the main gear and the assist gear, and an engagement mechanism disposed to couple with one of the first axial engagement mechanism or the second axial engagement mechanism; a shift mechanism disposed to move the dog ring axially along the outer surface of the assist driveshaft, the shift mechanism including an electric actuator; a first speed sensor disposed adjacent one of the shafts to monitor the rotational speed of the shafts; a single inverter electrically coupled to each of the first and second axial flux motors and the electric actuator; and a single controller controlling each of the first and second axial flux motors and the electric actuator. In one or more other embodiments, the electric drive assembly is a two-speed electric drive assembly that includes a main driveshaft with a main gear disposed along the main driveshaft; a first axial flux motor coupled to the main driveshaft and disposed to rotate the main driveshaft; an assist driveshaft with an assist gear disposed along the assist driveshaft; a second axial flux motor coupled to the assist driveshaft and disposed to rotate the assist driveshaft; an intermediate driveshaft with first, second and third intermediate gears each disposed along the intermediate driveshaft, wherein the third intermediate gear is fixed to the intermediate driveshaft; and an output driveshaft with an output gear affixed to the output driveshaft; wherein the main gear is continuously meshed with the second intermediate gear; wherein the assist gear is continuously meshed with the first intermediate gear; wherein the output gear is continuously meshed with the third intermediate gear; and wherein one of the main gear, assist gear, first intermediate gear or second intermediate gear is a freewheel gear disposed to be rotatable independently from the driveshaft about which it is mounted.

For any of the foregoing embodiments, the rotor assembly may include any one of the following elements, alone or in combination with each other:The first axial flux motor is adjacent the second axial flux motor.The main driveshaft extends through and is coaxial with the assist driveshaft.A first axial flux motor coupled to the main driveshaft.A second axial flux motor coupled to the assist driveshaft.A shift mechanism disposed adjacent the freewheel gear and axially movable to couple and decouple the freewheel gear and the driveshaft about which the freewheel gear is mounted.The shift mechanism comprises a hub affixed to a driveshaft and a shift sleeve slidingly engaged with the fixed hub.The output driveshaft is colinear with the main driveshaft and hollow assist driveshaft.The assist driveshaft is hollow and the main driveshaft coaxially extends through the assist driveshaft.The intermediate driveshaft is parallel with the main driveshaft and the assist driveshaft.The main driveshaft extends along a first axis and the intermediate driveshaft extends along a second axis spaced apart from the main first axis.The assist gear is the freewheel gear.The main gear is the freewheel gear.The first intermediate gear is the freewheel gear.The second intermediate gear is the freewheel gear.One or more bearings disposed between the assist gear and the assist driveshaft to permit the assist gear to rotated about the first axis independently of the assist driveshaft.The assist gear is the freewheel gear, the electric drive assembly further comprising a plurality of cooperating elements disposed on the assist gear and a plurality of cooperating elements disposed on the shift mechanism disposed to engage the plurality of cooperating elements disposed on the assist gear.A first speed sensor disposed adjacent the intermediate driveshaft to monitor the rotational speed of the intermediate driveshaft.A first speed sensor disposed adjacent one of the shafts to monitor the rotational speed of the shafts.A first speed sensor disposed adjacent the assist driveshaft to monitor the rotational speed of the assist driveshaft.The first speed sensor is electrically coupled to the actuator.A second speed sensor disposed adjacent the dog ring.A first speed sensor disposed adjacent the assist driveshaft to monitor the rotational speed of the assist driveshaft and a second speed sensor disposed adjacent the one of the main driveshaft or the first main gear.A single inverter electrically coupled to each of the first and second axial flux motors and the electric actuator.A single controller controlling each of the first and second axial flux motors and the electric actuator.The first axial flux motor comprises only a single rotor.The second axial flux motor comprises only a single rotor.The first and second axial flux motors each comprise only a single rotor.The first axial flux motor comprises a non-metal rotor.The second axial flux motor comprises a non-metal rotor.The first and second axial flux motors each comprise a non-metal rotor.The first and second axial flux motors each comprise a single rotor positioned between two stators.The output driveshaft is parallel with the intermediate driveshaft.The main driveshaft, the hollow assist driveshaft, the intermediate driveshaft and the output driveshaft are all spatially fixed relative to one another within the gearbox housing.A gearbox housing within which the gears and driveshafts are mounted, wherein the axial flux motors are external of the of the gearbox housing.Two or more first axial flux motors coupled to the main driveshaft.Two or more second axial flux motors coupled to the assist driveshaft.A first support plate and a second support plate disposed within the gearbox housing, wherein the assist driveshaft is supported by the gearbox housing and the first support plate, wherein the output driveshaft is supported by the gearbox housing and the second support plate, and wherein the main driveshaft extends from the assist driveshaft and is supported by the second support plate.The intermediate driveshaft is supported by the first and second support plates.The intermediate driveshaft is supported by the gearbox housing.Main gear has a first radius R1; assist gear has a second radius R2; first intermediate gear has a third radius R3; second intermediate gear has a fourth radius R4; third intermediate gear has a fifth radius R5; and output gear has a sixth radius R6.R3 is greater than R4, which is greater than R5 and R6 is greater than R1 which is greater than R2.

Although various embodiments have been shown and described, the disclosure is not limited to such embodiments and will be understood to include all modifications and variations as would be apparent to one skilled in the art. Therefore, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed; rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.