Multi-bar linkage mechanism electric drive system

Abstract

To provide an electric motor drive assembly that is capable of producing movement of a wheel that has two degrees of freedom.SOLUTION: An electric drive system includes: a rotary motor system including a hub assembly, a first rotating assembly, a second rotating assembly, and a third rotating assembly, where the hub assembly defines a rotational axis about which the first rotating assembly, the second rotating assembly and the third rotating assembly are coaxially aligned and are capable of independent rotational movement independent of each other; a multi-bar linkage mechanism connected to each of the first and third rotating assemblies and to the hub assembly and constraining movement of the hub assembly so that the rotational axis of the hub assembly moves along a defined path that is in a transverse direction relative to the rotational axis, where the multi-bar linkage mechanism causes the rotational axis of the hub assembly to translate along the defined path in response to relative rotation of the first rotating assembly and the third rotating assembly with respect to each other.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 393,982, filed September 13, 2016, and U.S. Provisional Patent Application No. 62 / 512,469, filed May 30, 2017, the entire teachings of which are incorporated herein by reference.

[0002] Embodiments relate generally to electric motor drive assemblies, and more particularly to electric motor drive assemblies capable of generating wheel motion with two degrees of freedom, e.g., rotational movement of the wheel and translational movement of the wheel transverse to the axis of rotation of the wheel. [Background technology]

[0003] More and more companies are developing vehicles that use electric motors as a means of propelling the vehicle. Because electric motors can be designed to be very compact and efficient, especially compared to combustion engines, they can also be used as in-wheel motors or hub motors, with an electric motor mounted within or very close to each wheel of the vehicle. Some newer, more innovative designs for vehicle drive systems are not only able to rotate the wheels, but also to move the wheels transversely to the axis of rotation. That is, they can generate two degrees of freedom: rotation to propel the vehicle along the road and translational movement to provide active suspension for the vehicle.

[0004] One example of such a system is described in U.S. Pat. No. 8,519,575 and is based on the use of Lorentz force linear actuators. To achieve two degrees of freedom, a linear-to-rotary converter is used, consisting of two opposing linear actuators and an arrangement of cam followers coupled to a cam assembly that supports the wheel rim. The linear actuators are positioned on either side of the wheel's axis of rotation and face each other. When the two opposing linear actuators operate synchronously to move the cam followers toward or away from each other, the linear-to-rotary converter converts that motion into pure rotation of the wheel. When the two linear actuators operate to move the cam followers in the same direction (i.e., one toward the axis of rotation and the other away from it), they thereby translate the cam assembly and the wheel to which they are attached in a direction transverse to the wheel's axis of rotation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 8,519,575 Summary of the Invention

[0006] In general, in one aspect, the invention features an electric drive system including a rotary motor system and a multi-bar linkage. The rotary system includes a hub assembly, a first rotating assembly, a second rotating assembly, and a third rotating assembly, where the hub assembly defines a rotation axis, and the first rotating assembly, the second rotating assembly, and the third rotating assembly are each coaxially aligned with the rotation axis and are capable of rotational movement about the rotation axis independently of the other two. A multi-bar linkage is coupled to each of the first and third rotating assemblies and to the hub assembly, and is configured to restrict movement of the hub assembly such that the rotation axis of the hub assembly moves along a defined path that is transverse to the rotation axis. The multi-bar linkage is configured to couple the hub assembly to the rotation axis. The rotation axis of the article is translated along a defined path in response to relative rotation of the first rotating assembly and the third rotating assembly relative to one another.

[0007] In general, in one aspect, the invention features an electric drive system including a rotary motor system and a multi-bar linkage. The rotary motor system includes a hub assembly, a magnetic rotor assembly, a first coil stator assembly, and a second coil stator assembly, the hub assembly defining an axis of rotation, and the magnetic rotor assembly, the first coil stator assembly, and the second coil stator assembly are each coaxially aligned with the axis of rotation and are capable of rotational movement about the axis of rotation independently of one another. A multi-bar linkage is coupled to each of the first and second coil stator assemblies and to the hub assembly. The multi-bar linkage constrains movement of the hub assembly such that the axis of rotation of the hub assembly moves along a defined path transverse to the axis of rotation and such that the axis of rotation of the hub assembly moves translationally along the defined path in response to relative rotation of the first and second coil stator assemblies relative to one another.

[0008] Other embodiments may include one or more of the following features: The multi-bar linkage is a four-bar linkage, such as a Watts linkage. The multi-bar linkage includes a support structure, a crankshaft assembly, a first swing arm, and a second swing arm, the first swing arm having a first end rotatably coupled to the crankshaft assembly and a second end rotatably coupled to the support structure at a first location on the support structure, and the second swing arm having a first end rotatably coupled to the crankshaft assembly and a second end rotatably coupled to the support structure at a second location on the support structure different from the first location on the support structure. The crankshaft assembly includes a hub assembly. The crankshaft assembly includes a crankshaft, a first crank arm extending in a first radial direction away from the crankshaft, and a second crank arm extending in a second radial direction away from the crankshaft. The first crank arm and the second crank arm are located at opposite ends of the crankshaft. The first radial direction is opposite the second radial direction.

[0009] Still other embodiments may include one or more of the following features: the electric drive system further includes a first torque link connecting the first coil stator assembly to the first swing arm and a second torque link connecting the second coil stator assembly to the second swing arm; and a wheel rim surrounding the axis of rotation, the magnetic rotor assembly coupled to the wheel rim such that the wheel rim rotates together with the magnetic rotor assembly about the axis of rotation; the wheel rim also surrounding the rotary motor system. The rotary motor system includes a first electric motor including a first magnetic rotor, a first coil stator assembly, a rotor bearing assembly enabling the first magnetic rotor to rotate about the axis of rotation, and a first coil bearing assembly enabling the first coil stator assembly to rotate about the axis of rotation independent of the first magnetic rotor, and a second electric motor including a second magnetic rotor, a second coil stator assembly, and a second coil bearing assembly enabling the second coil stator assembly to rotate about the axis of rotation independent of the first magnetic rotor and independent of the first coil stator assembly, the magnetic rotor assemblies comprising the first and second magnetic rotors coupled to each other to rotate together about the axis of rotation. The first and second electric motors are axial flux motors.

[0010] In general, in yet another aspect, the invention features a vehicle that includes a chassis and a plurality of wheel assemblies, at least one of which includes a rotary motor system including a hub assembly, a magnetic rotor assembly, a first coil stator assembly, and a second coil stator assembly, the hub assembly defining an axis of rotation, and the magnetic rotor assembly, the first coil stator assembly, and the second coil stator assembly each being coaxial with the axis of rotation. and are capable of rotational movement about the axis of rotation independently of one another. It also includes a multi-bar linkage coupled to each of the first and second coil stator assemblies and coupled to a hub assembly. The multi-bar linkage constrains movement of the hub assembly such that the axis of rotation of the hub assembly moves along a defined path that is transverse to the axis of rotation and such that the axis of rotation of the hub assembly moves translationally along a defined path in response to relative rotation of the first and second coil stator assemblies relative to one another. The wheel assembly also includes a wheel rim that circumscribes the axis of rotation, and a magnetic rotor assembly coupled to the wheel rim such that the wheel rim rotates with the magnetic rotor assembly about the axis of rotation.

[0011] Other embodiments of the wheel assembly may include one or more of the following features: The multi-bar linkage is a four-bar linkage, such as a Watts linkage. The multi-bar linkage includes a support structure, a crankshaft assembly, a first swing arm, and a second swing arm, the first swing arm having a first end rotatably coupled to the crankshaft assembly and a second end rotatably coupled to the support structure at a first location on the support structure, and the second swing arm having a first end rotatably coupled to the crankshaft assembly and a second end rotatably coupled to the support structure at a second location on the support structure different from the first location on the support structure. The crankshaft assembly includes a hub assembly. The crankshaft assembly includes a crankshaft, a first crank arm extending in a first radial direction away from the crankshaft, and a second crank arm extending in a second radial direction away from the crankshaft. The first crank arm and the second crank arm are located at opposite ends of the crankshaft. The first radial direction is opposite the second radial direction. The at least one wheel assembly also includes a first torque link connecting the first coil stator assembly to the first swing arm and a second torque link connecting the second coil stator assembly to the second swing arm. The rotary motor system includes a first electric motor including a first magnetic rotor, a first coil stator assembly, a rotor bearing assembly that enables the first magnetic rotor to rotate about the axis of rotation, and a first coil bearing assembly that enables the first coil stator assembly to rotate about the axis of rotation independent of the first magnetic rotor. The rotary motor system also includes a second electric motor including a second magnetic rotor, a second coil stator assembly, and a second coil bearing assembly that enables the second coil stator assembly to rotate about the axis of rotation independent of the first magnetic rotor and independent of the first coil stator assembly, and the magnetic rotor assembly includes first and second magnetic rotors that are coupled to each other to rotate together about the axis of rotation. [Brief explanation of the drawings]

[0012] The foregoing will become apparent from the following more particular description of exemplary embodiments, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the embodiments in an illustrative manner.

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating the Watt linkage. [Figure 2] FIG. 2 is a graph illustrating an exemplary translation path of the center point of the Watt linkage of FIG. [Figure 3] FIG. 3 is a schematic diagram of one embodiment of the Watt linkage drive system. [Figure 4] 4A-4D are a series of schematic diagrams illustrating the translational movement of components of the Watt linkage drive system of FIG. [Figure 5A] FIG. 5A shows a schematic diagram of another embodiment of a multi-bar linkage drive system. [Figure 5B] FIG. 5B shows the multi-bar linkage drive system of FIG. 5A with one of the stators removed to reveal a section of the rotor and the other stator. [Figure 6] 6A-6F are a series of schematic diagrams illustrating the translational movement of the multi-bar linkage drive system shown in FIGS. 5A and 5B. [Figure 7] FIG. 7 shows the components of a two-motor axial flux drive such as may be used in the multi-bar linkage drive system shown in FIGS. 5A and 5B. [Figure 8] FIG. 8 is a perspective view of a multi-bar linkage drive system for use in a vehicle. [Figure 9] FIG. 9 is a perspective view of the multi-bar linkage drive system shown in FIG. 8 with some components removed to reveal the internal structure. [Figure 10] FIG. 10 is a perspective view of a multi-bar linkage structure used in the multi-bar linkage drive system of FIG. 8. [Figure 11] 11A and 11B are orthogonal and perspective cross-sectional views of a two-motor axial flux drive used in the multi-bar linkage drive system shown in FIG. 8 with the coil stator assembly removed. [Figure 12] 12A and 12B are orthogonal and perspective cross-sectional views of one of the axial flux motors shown in FIGS. 11A-B including a coil stator assembly. [Figure 13] FIG. 13 is a schematic diagram illustrating a vehicle using the multi-bar linkage drive system shown in FIG. [Figure 14] FIG. 14 illustrates another embodiment of an integrated wheel and suspension assembly. [Figure 15] 15 is a cross-sectional view of a schematic diagram of an axial flux motor used in the integrated wheel and suspension assembly of FIG. 14. [Figure 16] 16 is a front view of a schematic diagram of an axial flux motor used in the integrated wheel and suspension assembly of FIG. 14. [Figure 17] 17 is a cross-sectional view of the schematic diagram of the integrated wheel and suspension assembly of FIG. 14. [Figure 18] 18A and 18B are side views of a schematic representation of the integrated wheel and suspension assembly of FIG. 14 illustrating the operation of the linkage arrangement during common modes of operation. [Figure 19] 19 is a side view of the schematic of the integrated wheel and suspension assembly of FIG. 14 illustrating the operation of the linkage arrangement during different modes of operation. [Figure 20] 20A and 20B show the arrangement illustrated by FIGS. 18A and 18B from the perspective of the interconnected linkages. [Figure 21] FIG. 21 shows an alternative arrangement of the link between the coil stator assembly and the suspension arm. [Figure 22] Figure 22 shows details of the linear bearing in the suspension arm and where the spindle is connected. [Figure 23]FIG. 23 shows a vehicle using the drive system shown in FIG. [Figure 24] FIG. 24 shows an alternative bearing arrangement for the electric motor shown in FIG. [Figure 25A] 25A-C show an alternative guide mechanism employing a swing arm to define the path along which the rotational axis is allowed to move laterally. [Figure 25B] Same as above. [Figure 25C] Same as above. DETAILED DESCRIPTION OF THE INVENTION

[0014] A description of an exemplary embodiment follows.

[0015] FIG. 1 is a schematic diagram illustrating a Watt linkage 100. The Watt linkage includes: Watt's linkage is a mechanical linkage arrangement in which a center point 105 of one of the linkages is constrained by the forces of the linkage to move along a defined path, most of which is substantially straight, as shown by line 110. Watt's linkage includes three movable rods, in this particular example, two long rods 115 and 120, connected together by a short rod 125 whose midpoint is point 105. The ends of the three rods are hinged so that they can rotate about hinge points. One end of rod 115 is connected to a fixed mount 126 at hinge point 127, and the other end of rod 115 is connected to the end of the shorter rod 125 at hinge point 128. One end of rod 120 is connected to the other end of the short rod 125 at hinge point 129, and the other end of rod 120 is connected to a second fixed mount 130 at another hinge point 131. Fixed mounts 126 and 130 are fixed in position relative to one another, for example, by being coupled to a common base or common structure. Although there are only three movable rods in this example, the Watts linkage is also commonly referred to as a four-bar linkage, since the connection between the two fixed mounts is considered a fourth bar.

[0016] As is apparent from FIG. 1 , the orientation of the rods can change even when constrained by their interconnected end points. So, for example, assume the initial position of the rods is shown by the solid line elements. If rod 115 rotates counterclockwise about hinge point 127 to another position shown in the dotted diagram labeled A, rod 120 will rotate clockwise about hinge point 131, causing the short rod 125 to rotate about the center point in a clockwise direction. Alternatively, if rod 115 rotates clockwise to another position shown in the dotted diagram labeled B, rod 120 will rotate counterclockwise, causing the short rod 125 to rotate about the center point in a counterclockwise direction. A feature of the Watt linkage is that the orientation of the rods can be changed in a manner that covers all possible orientations allowed by the linkage arrangement; the center point 105 of the short rod 125 describes a defined path, and the Watt linkage arrangement constrains that center point to always lie on the defined path. As shown by FIG. 2, the shape of the defined path is a figure eight, the majority of which is approximately linear.

[0017] The embodiment shown in Figure 3 uses a Watt linkage in combination with two electric motors to create a drive system 300 that can both drive a wheel (not shown) in rotation and controllably move it transversely to the wheel's axis of rotation—in other words, a drive system with two degrees of freedom.

[0018] Drive system 300 includes two electric motors 340 and 345 (illustrated by two triangular objects) fixed in position relative to one another. It also includes a linkage arrangement consisting of two equal-length swing arms 315 and 320 and a short crank arm 325, which correspond to rods 115, 120, and 125 shown in FIG. 1 and discussed above. At one end of swing arm 315, driven by electric motor 340, is a pulley 350, and at the distal end of swing arm 320, driven by electric motor 345, is another pulley 355. At the other end of swing arm 315, opposite pulley 350, is a second pulley 358. Attached to pulley 358 is a coaxially aligned elbow gear 360. Similarly, at the other end of swing arm 320, opposite pulley 355, is another attached, coaxially aligned pulley 363 with elbow gear 365, the same size as elbow gears 360 and 365. Located at the midpoint of crank arm 325 is crank gear 370, the same size and meshing with the two elbow gears 360 and 365. In swing arm 315, drive belt 375 connects pulley 350 to pulley 358, and in swing arm 320, another drive belt 380 connects pulley 355 to pulley 363. Pulleys 350 and 358 have the same drive ratio as pulleys 355 and 363.

[0019] To understand how linkage drive system 300 of Figure 3 operates, consider the case where two motors 340 and 345 rotate their attached pulleys 350 and 355 at the same speed in some direction (e.g., clockwise). In that case, belt 375 also drives pulley 360 in the clockwise direction at a speed determined by the ratio of the sizes of the two pulleys 350 and 358. Similarly, belt 380 drives pulley 365 in the clockwise direction at a speed determined by the ratio of the sizes of the two pulleys 355 and 363. Assuming both sets of pulleys (i.e., pulleys 350 and 358 and pulleys 355 and 363) have a 1:2 ratio, when motor 340 drives pulley 350 clockwise at a rotational speed 2ω, pulley 358 rotates clockwise at half that speed, i.e., ω. Because gears 360, 365, and 370 have the same ratio, gear 370 and its attached drive shaft 373 tend to rotate counterclockwise at a speed of ω. Similarly, when motor 345 drives pulley 355 clockwise at a rotational speed of 2ω, pulley 363 rotates clockwise at half that speed, i.e., ω, and gear 370 and its attached drive shaft 373 again tend to rotate counterclockwise at a speed of ω. Note that in this operating condition, i.e., both motors operating at the same speed, both motors rotate gear 370 at a speed of ω, and zero torque is applied to crank arm 325 supporting crank gear 370. That is, operating both motors 340 and 345 at the same speed and in the same direction results in a drive system that produces pure rotational motion of the drive shafts. Because no torque is applied to either linkage, their orientation or position does not change. Thus, under these drive conditions, the swing arms 315 and 320 remain fixed and "locked" in place.

[0020] It is clear from the above discussion that a different situation occurs when the motors are operating at different speeds. In that case, a torque is applied to the crank arm, and that torque causes the linkage to change orientation. To see why, consider what happens in the above situation when motor 345 is increased in speed slightly above 2ω. In that case, gear 365 is forced to rotate at a speed higher than the speed at which crank gear 370 rotates. The only thing that can happen is that gear 365, in addition to rotating, "walks" around crank gear 370. This causes a torque to be applied to crank 325 that causes the linkages to change their orientation relative to each other and move the drive shafts along the prescribed path imposed by the Watt linkage. In other words, this causes drive shaft 372 to move, or translate, transversely to the drive shaft axis. Furthermore, as long as the speeds of the two motors differ, the linkage will continue to change orientation, and the drive shaft axis will continue to move along its prescribed path.

[0021] Assuming that the two motors are operating at the same speed to produce pure rotational motion of the drive shaft, changing the position of the drive shaft from one point to another is accomplished by changing the phase relationship of the two motors. The rate at which the phase change is achieved determines the rate at which the drive shaft translates to its new location as determined by the Watt linkage.

[0022] In the preceding discussion, it was assumed for simplicity that the pulleys were the same size and the gears were the same size and had the same ratios. This is not the case. The pulley sizes can vary, as can the gear sizes. In either case, the key operating condition for achieving pure rotational motion is for both gears 365 and 360 to rotate crank gear 370 at the same speed. A change in the speed of one motor or the other then causes translational movement of drive shaft 372. In other words, a change in the phase of either motor 340 or motor 345 causes a corresponding translational movement of drive shaft 372.

[0023] 3 is used as a drive system for the wheels of a vehicle, motors 340 and 345 are mounted, for example, to the frame or chassis of the vehicle, and the wheel rim and tire are mounted to drive shaft 372. This arrangement can have two degrees of freedom and can be used to propel the vehicle as well as to actively control the height of the chassis above the road surface (which can serve to provide active shock absorption capabilities).

[0024] Another embodiment of a multi-bar linkage drive system combines the two motors of Figure 3 into a single electric motor with the axis of rotation located at the center of the crank. A schematic diagram of this other embodiment of a multi-bar linkage drive system 500 is shown in Figures 5A and 5B.

[0025] Drive system 500 includes two swing arms 515 and 520 and a crank assembly 534 connecting the corresponding ends of the two swing arms 515 and 520. Crank assembly 534 includes a crankshaft 535c with two crank arms 535a and 535b, each extending transversely to the axis of rotation of crankshaft 535c and oriented 180° relative to each other, at each end of crankshaft 535c. One end of swing arm 520 is pivotally connected to crank arm 535a via a bearing, while the other end of swing arm 520 is pivotally connected to mounting structure 570a via another bearing. Similarly, one end of swing arm 515 is pivotally connected to crank arm 535b (not shown) via its own bearing, while the other end of swing arm 515 is pivotally connected to mounting structure 570b via yet another bearing. This combination of elements creates a four-bar linkage arrangement similar to that shown in Figure 3, restricting the axis of rotation of the crankshaft to follow a defined path as the linkage orientation changes.

[0026] The electric motor in drive system 500 includes two stator assemblies 540 and 545 and a rotor assembly 530, each mounted on a crankshaft 535c using bearings so that it can rotate independently of the other two components. Rotor assembly 530 includes a ring of bolts 550 around its periphery for mounting a wheel rim and tire (not shown) onto rotor assembly 530.

[0027] Note that bearings are not shown in FIGS. 5A and 5B to simplify the drawings. However, they are explicitly shown in FIG. 7, which will be discussed later. Furthermore, as will be clearer in connection with FIG. 7, the motor of the described embodiment is an electric axial flux motor, the stator assembly is a coil stator assembly, and the rotor assembly is a magnetic rotor assembly. Also, note that the term "stator" is not meant to be limiting in this context and may be interpreted to imply that the components being referenced are stationary and do not rotate. The stator assemblies described herein are capable of rotating about an axis of rotation that may or may not be the same as the axis of rotation of the rotor assembly. This feature is important because, at least in some embodiments, the drive system can produce two degrees of freedom: rotation and translation.

[0028] 5A and 5B, each swing arm 515 and 520 is mechanically coupled to its corresponding stator assembly 540 and 545. Swing arm 520 has two wing extensions 536a and 536b. Torque links 539a and 539b connect wing extensions 536a and 536b, respectively, to stator assembly 545. Similarly, on the other side of the drive system, swing arm 515 also has two wing extensions 537a and 537b (not shown). Torque links 539a and 539b also connect wing extensions 536a and 536b, respectively, to stator assembly 545. Similarly, on the other side of the drive system, swing arm 515 also has two wing extensions 537a and 537b (not shown). Wing extensions 537a and 537b, respectively, connect stator assembly 540. Torque links 539a and 539b are for transferring torque generated by stator assembly 545 to swing arm 520, and torque links 538a and 538b are for transferring torque generated by stator assembly 540 to swing arm 515.

[0029] Although stator assemblies 540 and 545 are each freely rotatable about the axis of crankshaft 535c by being mounted on the crankshaft with bearings, the torque links connecting them to the multi-bar linkage restrict their movement and prevent them from rotating freely without restriction. In effect, the torque links restrict the rotation of the stator assemblies to within a narrow range of allowable rotation. This limited range of rotation allows for the use of wiring harnesses to connect drive signals to the coils in the stator assemblies, rather than using commutation or some other means to provide drive signals to the coils on the coil stator assemblies.

[0030] Note that in FIG. 5A there are four points labeled A, B, C, and D. These points define four distances: AB, AC, CD, and BD. AB represents the length of the torque link, CD represents the length of the crank arm, AC represents the radial distance between the axis of the crankshaft and the attachment point of the torque link to the stator assembly, and BD represents the distance between the point where the crank arm connects to the swing arm and the point where the torque link connects to the swing arm extension wing. In the described embodiment, these lengths are designed to have the following relationship to one another: AB = CD and AC = BD, which defines a parallelogram. As a result of this arrangement, rotation of the stator assembly relative to the vertical translates into a corresponding equal rotation of the swing arm about its attachment point to the mounting structure and in the same direction. In other words, when the stator assembly 545 rotates clockwise, this causes the swing arm 520 to move in an upward direction, which also corresponds to a rotation of the swing arm 520 in a clockwise direction about the mounting structure 570a.

[0031] The multi-bar linkage drive system of Figures 5A and 5B operates in a manner similar to that of the embodiment shown in Figure 3. When a drive signal is applied to each stator assembly 540 and 545 such that both drive signals generate the same torque, rotating rotor assembly 530 clockwise, net rotational motion of rotor assembly 530 results. (Note that the direction of rotation is viewed from the perspective of one side of the motor, in this case the side where stator assembly 545 is located, and this generally applies throughout the remaining description.) The orientation of swing arms 515 and 520 remains fixed, and crankshaft 535c does not move laterally. This is because the torque imposed on crankshaft 535c by stator assembly 540 is canceled by the torque imposed on crankshaft 535c by stator assembly 545. The torques on the linkages are equal and opposite, producing no net torque on either linkage.

[0032] On the other hand, if the drive signal on one stator assembly is changed relative to the other, there is a net torque on the crank assembly, causing it to change its orientation / position. As a result, the crankshaft is rotating, but also moving along the path defined by the multi-bar linkage.

[0033] To understand how the multi-bar linkage drive system works to translate the crankshaft, consider the case where the magnetic rotor assembly is prevented from rotating by something, causing the swing arm to move. This moves (or translates) the crankshaft 535C and rotor assembly 530 (to which the wheels are attached) from an upper position (FIG. 6A) to a lower position (FIG. 6F), showing various relative positions of the drive system elements. 6A-6F. The downward arrows in each of the figures indicate the direction in which the rotor assembly and crank assembly are moved. As rotor assembly 540 moves downward from the position shown in FIG. 6A, crank assembly and swing arms 515 and 520 move downward accordingly. Simultaneously, torque links 538 and 539 rotate stator assemblies 540 and 545 in the same direction as swing arms 515 and 520 rotate about their respective mounts 570a and 570b. The downward movement of swing arm 520 represents a counterclockwise rotation about its mount 570b. Stator assembly 545 is therefore forced to rotate counterclockwise about crankshaft 535c by the same amount. On the other side of the multi-bar linkage drive system, the downward movement of swing arm 515 represents a clockwise rotation about its mount 570a. As a result, stator assembly 540 is forced to rotate clockwise about crankshaft 535c.

[0034] This relative motion of the elements continues as the axis of rotor assembly 530 moves further down the path defined by the multi-bar linkage of the axis of crankshaft 535c, as shown in Figures 6C-F. Note that stator assemblies 540 and 545 shown in the figures have reference slots to help visualize the rotation of these elements as rotor assembly 530 moves toward its down position shown in Figure 6F. Also note that there are arrows identifying the direction of rotation of the stator assemblies.

[0035] It is clear that the movements illustrated in Figures 6A-F can be produced by applying appropriate drive signals to stator assemblies 540 and 545. The drive signals must be such that they cause stator assemblies 540 and 545 to rotate in opposite directions relative to one another while simultaneously applying a net torque to rotor assembly 530 that results in no, or zero, rotation of rotor assembly 530. For example, when stator 545 applies torque (via electromagnetic forces on rotor assembly 530) to rotate itself counterclockwise (causing the rotor assembly to rotate clockwise), it also exerts a force on swing arm 520 via torque links 539a and 539b, which push up on swing arm 520. A balancing force on crank assembly 534 must then be created, pushing downward on crank assembly 534 (since the sum of the forces is zero at small accelerations). Crank assembly 534 is then pushed down on swing arm 520. As a result, swing arm 520 has forces pushing it up where it connects to crank assembly 534 and where it connects to torque links 539a and 539b. In effect, a rotational torque is applied to swing arm 520, causing it to begin to rotate counterclockwise, i.e., in the same direction as stator assembly 545. A similar differential occurs at stator assembly 540 and swing arm 515 on the other side of rotor assembly 530.

[0036] If both stator assemblies 540 and 545 rotate in a manner that rotates the corresponding swing arms 515 and 520 in an upward direction, the swing arms 515 and 520 (and rotor assembly 530) move upward. If both stator assemblies 540 and 545 rotate the swing arms 515 and 520 in a downward direction, the swing arms 515 and 520 (and rotor assembly 530) move downward. If one swing arm rotates upward while the other swing arm rotates downward, if the torques are balanced, the swing arms 515 and 520 will not move.

[0037] In summary, to rotate rotor assembly 530 without translational movement, equal torques are applied to both stator assemblies 540 and 545 in the same direction. In that case, the moments applied to each swing arm cancel and the rotor assembly rotates. To translate rotor assembly 530, equal but opposite torques are applied to both stator assemblies 540 and 545. This causes swing arms 515 and 520 to move in the same direction. Move in the direction.

[0038] Because the multi-bar linkage drive system is a linear system, rotation of rotor assembly 530 and translation of crankshaft 535c (and rotor assembly 530) can be achieved by adding the signals necessary to generate each type of motion separately. In other words, using the appropriate drive signals, the rotor assembly can be rotated and simultaneously translated upward or downward.

[0039] In the above discussion, inertial effects are ignored. When inertial effects are added, they change the magnitude of the torque and the required force, but the general principles of how a multi-bar linkage system operates remain unchanged. Furthermore, the above discussion explained that rotation occurs when the torques are equal and of the same sign, and motion (or translation) occurs when the torques are equal and of opposite sign. While this is true in some respects, it is not true at all points along the prescribed path of translation (see Figure 2). In general, there is a little "cross torque" or "non-orthogonality" elsewhere.

[0040] An example of the structure of an electric drive motor 600 that can be used in the previously described embodiments is shown in Figure 7. It includes two coaxially arranged axial-flux motors coupled along a common axis of rotation. In this case, they are mounted on crank assembly 602, which corresponds to crank assembly 534 discussed with the multi-bar linkage drive system shown in Figure 5. Crank assembly 602 includes crankshaft 603a with crank arms 603b and 603c located on either end of crankshaft 603a and oriented at 180° relative to each other. In Figure 7, the two motors are identified as Motor 1 and Motor 2.

[0041] Generally, each axial-flux motor has a coil stator assembly 606 sandwiched between two magnetic rotor assemblies 608. Each coil stator assembly 606 is a circular disk 610 rotatably mounted on a crankshaft 603a, with an array of coils 612 disposed around and within an annular region of the disk. Each magnetic rotor assembly 608 is also a circular disk rotatably mounted on the crankshaft 603a. Attached to each disk of each magnetic rotor assembly 608 is an array 614 of radially oriented bar-shaped permanent magnets distributed around the annular region of the disk. The magnets 614 on the magnetic rotor assembly 608 are aligned with the array 612 of coils on the coil stator assembly 606.

[0042] The magnetic rotor assemblies 608 of the two coaxially aligned motors are rigidly fixed to a common hub assembly 616, which rides on bearings 618 located between the hub assembly 616 and the crankshaft 603a, so that the magnetic rotor assemblies 608 are free to rotate around the crankshaft 603a as a unit.

[0043] The disks of the coil stator assemblies 606 sandwiched between the magnetic rotor assemblies 608 have a circular central opening 620 through which the hub assemblies 616 pass without contacting the disks. Thus, the coil stator assemblies 606 and hub assemblies 616 can rotate independently of one another. Each coil stator assembly 606 is supported around its periphery by a housing 622, which is rotatably mounted on and rides on the crankshaft 603a via a set of bearings 624. The bearings 624 also allow the housings 622, as well as their supporting coil stator assemblies 606, to rotate freely on the crankshaft 603a so that the magnetic rotor assemblies 608 can move. All of the magnetic stator assemblies 608 are supported around the crankshaft 603a by a housing 622. 3a, but each of the coil stator assemblies 606 rotates independently of the other coil stator assemblies and the hub assembly 616 on crankshaft 603a.

[0044] The magnets in the two arrays of permanent magnets are positioned relative to one another to generate axial magnetic fields that reverse direction at regular intervals as one moves around the annular region of the disk. These axial magnetic fields generated by the magnet arrays intersect with the radially oriented windings of the coils 612 on the coil assembly 608. When a current is passed through the coil windings, the interaction of the current with the magnetic field generates a Lorentz force on the magnetic rotor assembly 608 and the coil stator assembly 606. The tangentially directed force imparts a torque to the disks, causing them to rotate, causing the disks of the magnetic rotor assembly 608 to rotate in one direction about the crankshaft 603a and the disks of the coil stator assembly 606 to rotate in the opposite direction about the crankshaft 603a.

[0045] As previously described, when the electric motor is coupled in a linkage arrangement, the magnetic rotor assembly is free to rotate about the crankshaft, but each coil stator assembly is constrained by the linkage to operate only within a limited range of rotation. The magnetic rotor assembly 608 is primarily used to apply torque to the wheel to which it is coupled, while the coil stator assembly 606 is primarily used to apply torque to the linkage, thereby changing their orientation relative to each other, as previously described.

[0046] An embodiment incorporating a multi-bar linkage drive system into a wheel that may be used on a vehicle is shown in Figures 8-12B. Motorized wheel assembly 800 includes a tire 804 mounted on a rim 806. A dual-axis flux motor is housed within the space enclosed by rim 806 and is coupled to a multi-bar linkage system 801, which is of a similar design to those previously described.

[0047] 10, multi-bar linkage system 801 includes a support structure 807 attached to a vehicle suspension by a coupling 809. At one end of support structure 807 is a swing arm 815 attached to support structure 807 by a spring-loaded bearing mechanism 816. At the other end of support structure 807 is another swing arm 820 attached to the support structure by another spring-loaded bearing mechanism 817.

[0048] Without the springs in spring-loaded bearing structures 816 and 817, the drive system would be physically positioned closest to the ground when no power is applied to the chassis or vehicle to which the drive system is mounted (i.e., swing arms 815 and 820 are in their uppermost position). The springs in spring-loaded bearing assemblies 816 and 817 hold the drive system in the intermediate or normal position without having to constantly supply power to the drive motor to accomplish that task.

[0049] The end of each swing arm 815 and 820 faces where bearing structures 817 and 816, respectively, are rotatably coupled to crank assembly 834. Crank assembly 834 is comprised of crankshaft 803a with two crank arms 803b and 803c at each end of crankshaft 803a. Crankshaft 803a supports two sets of bearings 818 and 824. Bearing 818 rotatably supports hub assembly 810 (see FIGS. 11A and 11B) to which magnetic rotor assemblies 812 are attached, and bearing 824 rotatably supports housing 822 (see FIGS. 8 and 9) which holds coil stator assembly 814 between magnetic rotor assemblies 812. Bearing 818 rotatably supports all of magnetic rotor assemblies 812 in hub assembly 810. 2 are mounted to rotate around crankshaft 803a, while bearings 824 also allow support housings 822, together with their respective coil stator assemblies 814, to rotate independently of one another around crankshaft 803a. Each housing 822 has a cover 842 through which a cable passes to connect to and provide a drive signal to support coil stator assembly 814.

[0050] Each magnetic rotor assembly 812 consists of two mechanically linked disks 813. Each disk 813 carries an array 826 of permanent magnets arranged around an annular region of the disk 813. The magnetic moments of the permanent magnets are axially aligned and periodically move in opposite directions as one moves around the circumference of the rotor assembly. The magnets 826 on one disk 813 align with the magnets 826 on the other disk in the pair so that their magnetic moments point in the same direction, reinforcing the magnetic field seen by the coils in the coil stator assembly.

[0051] 11A and 11B, hub assembly 810 is made of three pieces: a rim support disk 809 sandwiched between a pair of rotor support assemblies 819 and secured by a ring of bolts 821. Each rotor support assembly 819 supports a pair of magnetic rotor assemblies 812. A coil stator assembly 814 (see FIGS. 12A and 12B) is positioned between each pair of magnetic rotor assemblies 812. Hub assembly 810 defines a bore 811 through which crankshaft 803a extends, along with bearings 818 and 824.

[0052] Each swing arm 815 and 820 includes a wing extension plate 830 bolted to the end of the swing arm that is coupled to crankshaft assembly 834. Wing extension plate 830 provides two points at which torque link 832 is connected to the swing arm. The other end of the torque link is connected to housing 822. As previously mentioned, torque link 832 provides a way for torque generated by coil stator assembly 814 to be transferred to swing arms 815 and 820.

[0053] FIG. 13 is a schematic diagram of a vehicle 900 including a four multi-bar linkage drive system 920, as described above, mounted on a passenger carrier or chassis 910. In this example, each drive system 920 occupies the space normally occupied by a typical vehicle wheel assembly. While this particular example is characterized as having four multi-bar linkage drive systems 920, it is possible to have only two such drives, at either the front or rear wheels. Additionally, other types of vehicles utilizing multi-bar linkage drive systems are envisioned. For example, vehicles with one, two, three, or more wheels can envision one or more of the wheels being implemented using a multi-bar linkage drive system.

[0054] Figure 14 shows another embodiment of an integrated wheel and suspension assembly 1010 that is capable of generating both rotational motion of the tire 1012, which propels the vehicle forward, and translational motion of the tire (i.e., raising and lowering), which provides part of the active suspension for the vehicle to which the wheel and suspension assembly 1010 is mounted. It includes an axial-flux electric motor assembly 1100 supported by a suspension fork having two suspension arms 1020a and 1020b to which a motor assembly 1100 is slidably mounted so that the motor assembly can slide up and down under the control of the motor assembly. A pair of crescent-shaped linkages 1030a and 1030b, only one of which is visible in Figure 14, physically connect the rotatable portion of the electric motor assembly to fixed points on the suspension arms 1020a and 1020b. A connecting bracket 1036 near the upper ends of the suspension arms 1020a and 1020b clamps each of the arms 1020a and 1020b and holds them rigidly in a fixed position relative to each other. .

[0055] 15, a motor assembly 1100 includes two coil stator assemblies 1102a and 1102b and a magnetic rotor assembly comprised of three magnetic rotors, including outer magnetic rotors 1104a and 1104b and a central magnetic rotor 1104c. One coil stator assembly 1102a is sandwiched between and spaced apart from the magnetic rotors 1104a and 1104c, while the other coil stator assembly 1102b is sandwiched between and spaced apart from the magnetic rotors 1104c and 1104b. The outer magnetic rotors 1104a and 1104b are each substantially circular annular structures disposed along a hub assembly or central cylindrical spindle 1106, with their axes aligned with the axis of the spindle 1106. The central magnetic rotor 1104c is mounted on the spindle 1106 via a bearing assembly 1108 so that it can freely rotate about an axis of rotation 1107, in this case defined by the axis of the spindle 1106. Around the periphery of the central magnetic rotor 1104c are mounted two other magnetic rotors 1104a and 1104b, a cylindrically shaped collar 1110 with one magnetic rotor 1104a on one side of the collar 1110 and the other magnetic rotor 1104b on the other side of the collar 1110. With this arrangement, the two outer magnetic rotors 1104a and 1104b rotate around the axis of rotation and the spindle 1106 together with the central magnetic rotor 1104c.

[0056] Coil stator assemblies 1102a and 1102b, which are also generally disk-shaped structures, are mounted to spindle 1106 by bearing assemblies 1109a and 1109b, respectively, so that they can rotate independently of each other and the magnetic rotor assembly about an axis of rotation defined by the axis of spindle 1106. Each coil stator assembly 1102a and 1102b has an annular region 1112 within which is an array 1114 of coils distributed around the disk. As shown in FIGS. 14 and 15 , there are also connectors 1116 that electrically connect to the coils within the array of coils and through which drive signals are delivered to those coils. The coils are fabricated or wound to create a generally radially oriented current path through which a drive current flows to operate the motor.

[0057] Each outer magnetic motor 1104a and 1104c is annular and has an annular region 1118, and the central magnetic rotor 1104c is disk-shaped and has an annular region 1120. When the three magnetic rotors are mounted on the spindle 1106, these annular regions 1118 and 1120 generally align with the annular regions 1112 of the coil stator assemblies 1102a and 1102b. Around each magnetic rotor and within the annular region is an array 1122 of permanent magnets. As will be explained in more detail shortly, the magnets 1122 are positioned to intersect with the coil windings of the coil stator assemblies and generate an axially oriented magnetic field that alternates from one axial direction to the opposite axial direction as one moves around the rotor.

[0058] The illustrated embodiment also includes a spoke assembly 1124 that surrounds and extends away from the collar 1110 and supports a rim 1126 to which a tire (not shown) can be attached. The spoke assembly is used as a weight saving measure instead of a solid ring of material. There is also a brake disc 1128 attached to the spoke assembly 1124, as well as a brake caliper 1129 attached to the suspension arm 1020b.

[0059] The motor assembly can be viewed as two coaxially arranged axial flux motors coupled along a common axis of rotation, shown in Figure 15 as Motor 1 on the left and Motor 2 on the right. Motor 1 has magnetic rotor 1104a and magnetic rotor 1104c. Motor 1 is represented by coil stator assembly 1102a sandwiched between the left half of magnetic rotor 1104c and magnetic rotor 1104b, and motor 2 is represented by coil stator assembly 1102b sandwiched between the right half of magnetic rotor 1104c and magnetic rotor 1104b. In this case, the magnetic rotors are all coupled together and thereby rotate together.

[0060] How the motor assembly 1100 is incorporated into the integrated wheel and suspension assembly 1010 and how the overall system operates to generate both rotational and translational motion will now be described with reference to Figures 16, 17, 18A, and 18B.

[0061] At the end of the spindle 1106 are two linear bearings 1140a and 1140b, held within hollow regions inside the suspension arms 1020a and 1020b, respectively. The linear bearings 1140a and 1140b can slide up and down within their respective suspension arms 1020a and 1020b, thereby allowing the spindle 1106 to move up and down as well. The linear bearing 1140b of the illustrated embodiment is shown in more detail in FIG. 22. It includes two blocks 1150a and 1150b fixed within the hollow space inside the arms 1020b. Between and rigidly connected to the two blocks 1150a and 1150b is a cylindrical guide 1152. A collar bearing 1154 surrounds the guide 1152 and allows it to be raised and lowered. The spindle 1106, which supports the motor and wheels, is connected to the collar bearings 1154.

[0062] 18A and 18B, crescent linkage 1030a connects between a fixed location on suspension arm 1020a and a fixed location on coil stator assembly 1102a. The connection to suspension arm 1020a is via bearing mount 1142a and the connection to coil stator assembly 1102a is via another bearing mount 1144a. Similarly, crescent linkage 1030b connects between a fixed location on suspension arm 1020b and a fixed location on coil stator assembly 1102b. The connection to suspension arm 1020b is via bearing mount 1142b and the connection to coil stator assembly 1102b is via another bearing mount 1144b.

[0063] The crescent-shaped linkage is attached to the suspension arm and coil stator assembly so that there is rotational symmetry between them about a longitudinal axis 1146 that intersects the axis of the spindle 1106. That is, if the wheel and suspension assembly 1010 is rotated 180° about its axis 1146, the position of the linkage and its attachment point will appear the same.

[0064] Note that the linkage causes the wheel to move as follows: If coil stator assembly 1102b rotates clockwise by a certain amount, as shown in FIG. 18A, this has two results. It causes spindle 1106 and bearings 1140a and 1140b to be pushed downward within suspension arms 1020a and 1020b, which in turn causes coil stator assembly 1102a to rotate counterclockwise by the same amount. The resulting configuration is shown in FIG. 18B.

[0065] This relates to how the system operates when drive currents are applied to coil stator assemblies 1102a and 1102b. First, assume that drive current is applied to coil stator assembly 1102a, causing it to rotate in a counterclockwise direction and generating a torque that rotates the magnetic rotor assembly (and wheel) clockwise. Also assume that drive current is applied to coil stator assembly 1102b, causing it to rotate clockwise (as indicated by the arrow identified by the letter B). Assume that the coil stator assemblies 1102a and 1102b generate a torque that rotates the magnetic rotor assembly (and wheel) counterclockwise. If the resulting torques generated by the drive currents applied to coil stator assemblies 1102a and 1102b are the same magnitude, the torque generated on the magnetic rotor assembly by coil stator assembly 1102a will be exactly balanced by the torque generated on the magnetic rotor assembly by coil stator assembly 1102b. Thus, the magnetic rotor assembly experiences zero net torque and does not rotate with the attached wheel, remaining stationary. However, coil stator assemblies 1102a and 1102b will rotate in opposite directions to each other, as indicated by the arrows. This causes linkages 1030a and 1030b to push spindle 1106 and the attached tire downward or reverse, lifting the vehicle to which the suspension arms are attached.

[0066] Now consider another mode of operation, which will be explained with the aid of FIG. 19. In this case, it is assumed that the drive currents applied to coil stator assemblies 1102a and 1102b are both such that they rotate the magnetic rotor assembly in the same direction. More specifically, the drive current applied to coil stator assembly 1102a rotates the magnetic rotor assembly in a clockwise direction while also rotating coil stator assembly 1102a clockwise (as illustrated by the arrows identified with the letter E). Also, the drive current applied to coil stator assembly 1102b rotates the magnetic rotor assembly clockwise while also rotating coil stator assembly 1102b counterclockwise (as illustrated by the arrows identified with the letter E). Linkage 1030a transfers the torque imparted by coil stator assembly 1102a to spindle 1106, causing it to move downward, while linkage 1030b transfers the torque imparted by coil stator assembly 1102b to spindle 1106, causing it to move upward. Assuming the drive currents applied to coil stator assemblies 1102a and 1102b are selected to generate torques of the same magnitude, the forces imposed on spindle 1106 will closely balance each other and spindle 1106 will remain stationary (i.e., nothing will move up or down). Meanwhile, because both coil stator assemblies 1102a and 1102b are rotating the magnetic rotor assembly in the same direction, the wheel will rotate in that direction.

[0067] In summary, there are two modes of operation, referred to as the common mode and the differential mode. In the common mode, the drive signals applied to the two coil stator assemblies generate torques on the magnetic rotor assembly that are equal and have the same sign. During common mode operation only, the wheel rotates, but there is no translational movement of the wheel (up or down). In the differential mode, the drive signals applied to the two coil stator assemblies generate torques on the magnetic rotor assembly that are equal and have opposite signs. During differential mode operation only, the wheel does not rotate, but there is translational movement of the wheel (up or down). By appropriately selecting the drive currents to the coil stator assemblies, a combination of both types of motion can be produced simultaneously.

[0068] Conceptually, the described linkage system can be viewed as two mechanical systems that work together to generate translational movement of the wheel. One system is formed by the suspension fork and internal linear bearing that constrain the spindle to move along a defined path, in this case a linear path. The other system is formed by a linkage arrangement that converts the relative rotational movement of the two coil stator assemblies with respect to each other into translational movement of the spindle (or rotating element) along the path predetermined by the suspension fork. Note that in the illustrated embodiment, the linkage arrangement corresponds to a four-bar linkage arrangement.

[0069] The two mechanical systems are illustrated by Figures 20A and 20B. The inner linear bearing 1140b constrains the axis of the spindle 1106 to move up and down along a linear path defined by guides within the linear bearing. The linkage arrangement that moves the spindle along its path in response to torque generated by the electric motor is a multi-bar linkage including four bars or links 1180a, 1180b, 1182a, and 1182b. Two of the four links are represented by elements that connect the coil stator assembly 1102b to a fixed location on the suspension arm. On one side is link 1180b between a point on the coil stator assembly 1102b (represented by bearing mount 1144b) located a fixed distance from the axis of rotation of the coil stator assembly 1102b and a fixed point 1142b on the arm 1102b. On the other side (partially hidden in the side view shown), there is link 1180a between a point on coil stator assembly 1102a (represented by bearing mount 1144a) located a fixed distance from the axis of rotation of coil stator assembly 1102a and a fixed point 1142a on arm 1020a. The remaining two links 1182a and 1182b are represented by connections between spindle 1106 and bearing mounts 1144b and 1144a on coil stator assemblies 1102b and 1102a, respectively. In Figures 20A and 20B, these two links are represented by elements 1182b and 1182a. Note that the four links effectively have their ends connected at hinge points. Coil stator assemblies 1102a and 1102b apply an appropriate torque to links 1182a and 1182b, causing them to rotate and thereby change the physical arrangement of the four links, thereby reconfiguring the links, which moves the spindle along a linear path defined by the linear bearings.

[0070] FIG. 23 illustrates a vehicle 1200 that includes four electric motor drive systems 1202, one for each wheel, driving one of the four wheels (only two drive systems are shown in side view). Each electric drive system 1202 occupies the space normally occupied by a typical wheel and suspension assembly and is mounted to the frame or body of the vehicle. While the illustrated embodiment includes four drive systems 1202, one for each wheel, a vehicle can use drive systems for only the front (or rear) wheels. Other embodiments include one-, two-, and three-wheeled vehicles or personal transport systems with one or more wheels driven by the electric drive systems described herein.

[0071] In the above-described embodiment, the linkages have a crescent shape and are secured to points on the suspension arms that are aligned with one another. However, the shape of the linkages and their securing points is not particularly important. In the described embodiment, the crescent shape was selected to meet the specific physical constraints imposed by the illustrated design. Other shapes and / or arrangements are certainly possible. For example, referring to FIG. 21 , straight bar linkages 1160a and 1160b are used, with each linkage secured to tabs 1162a and 1162b, respectively, that extend away from the fork suspension members.

[0072] It should be noted that in the described embodiment, each coil stator assembly is connected by a corresponding linkage to a fixed point on the support structure (i.e., the suspension arm) and is constrained by the wheel axle to move only along a path defined by a linear bearing that slides within the suspension arm. The linear bearing is a specific example of a sliding mechanism, although other embodiments may also be used. Other than a sliding mechanism that constrains the movement of the axle along a predetermined transverse path may be used. For example, a simple swing arm or arrangement of a swing arm between the vehicle frame and the wheel axle could be used. In that case, the up and down movement of the wheel would not follow a strictly linear path, but rather the path would be a curve with a radius defined by the length of the swing arm.

[0073] 25A-C show an example embodiment for using swing arm 1194 to define the path along which spindle 1106 can travel, i.e., the arc with a radius determined by the length of swing arms 1194a and 1194b (visually blocked by swing arm 1194a in the figures). The frame of the vehicle or support to which the drive system is coupled is represented by block 1188. The linkage arrangement that moves spindle 1106 along its path in response to torque generated by the electric motor is a multi-bar linkage including four bars or links 1190a, 1190b, 1192a, and 1192b. Two of the four links are represented by elements that connect the coil stator assembly to a fixed position on frame 1188. On one side there is a link 1190b between a point on coil stator assembly 1102b (represented by bearing mount 1194b) located a fixed distance from the axis of rotation of coil stator assembly 1102b and a fixed point 1196b on frame 1188. On the other side of the motor (partially hidden in the side view shown), there is a link 1190a between a point on coil stator assembly 1102a (represented by bearing mount 1194a) located a fixed distance from the axis of rotation of coil stator assembly 1102a and a fixed point 1196a on frame 1188. (Note that the two fixed points 1196a and 1196b on the frame 1188 are collinear and the same distance from the spindle 1106.) The remaining two links are represented by the connection between the spindle 1106 and the bearing mounts 1196b and 1196a on the coil stator assemblies 1102b and 1102a, respectively. In FIGS. 25A-C, these two links are represented by components 1192b and 1192a. Note that the four links effectively have their ends connected at hinge points. The coil stator assemblies 1102a and 1102b apply the appropriate torque to the links 1192a and 1192b, causing them to rotate, thereby changing the physical arrangement of the four links and reconfiguring the links.The reconfiguration of the link forces the spindle to move along a curved path defined by swing arms 1194a and 1194b.

[0074] 25A-C, as coil stator assembly 1102b rotates clockwise (as indicated by the solid curved arrow) and coil stator assembly 1102a rotates counterclockwise (as indicated by the dashed curved arrow), the distance between spindle 1106 and the fixed points of links 1190a and 1190b increases, pushing the wheel in a downward direction. Rotating the coil stator assembly in the opposite direction pulls the wheel up.

[0075] Other known approaches are also possible. There are also multi-bar linkages that can be used, examples of which are well known to those skilled in the art.

[0076] It is also clear from the foregoing that the use of the word "stator," for example, in the case of a coil stator assembly, is not meant to indicate that the component is stationary and unable to rotate or move. While in many cases the word may be given this more restrictive meaning, it is not intended as used herein. It is also clear from the foregoing that the coil stator assembly also rotates about the axis of rotation of the motor assembly.

[0077] It should be understood that the bearing arrangement used in the described embodiment is only one of many alternatives that can be used, and that the two coil stator assemblies and the magnetic rotor assembly can rotate about their axes of rotation independently of one another. There is no need to use a spindle as one of the bearing surfaces. Figure 24 shows an alternative arrangement in which bearings 1209a and 1209b rotatably mount the coil stator assembly on the magnetic rotor assembly. Additionally, the hub assembly, while represented by the spindle 1106, may be another arrangement that supports the two motors along their axes of rotation.

[0078] Although the described embodiments make specific reference to using the second degree of freedom available from the drive system to provide active suspension for a vehicle, that second degree of freedom may be used for other purposes depending on the application in which the drive system is used. For example, the drive system may be used as a motor for an airplane or other aircraft, in which case the second degree of freedom may be used, for example, to control the pitch of the blades. If the drive system is used in a mechanical device, the second degree of freedom may be used for other purposes requiring some linear or translational movement.

[0079] Other embodiments are within the scope of the claims. For example, while a specific four-bar linkage, i.e., a Watt linkage, is described, there are numerous other multi-bar linkages that operate similarly and can be used in place of the Watt linkage. Other examples, without intending to be limiting, include four-bar linkages, Chebyshev linkages, and multi-bar linkages with a number of link bars different from the Porcellier-Lipkin linkage. Furthermore, electric motors other than axial-flux motors can be used, including, for example, other types of electric motors with magnetic rotor and coil stator assemblies, or coil rotor and magnetic stator assemblies, or electric motors based on switching reluctance technology, or current commutators, or single-phase or multi-phase drives, or DC drives, etc.

[0080] While exemplary embodiments have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the scope of the embodiments encompassed by the appended claims.

Claims

1. A magnetic rotor assembly; a first drive signal causing a first coil stator assembly to apply a first torque to the magnetic rotor assembly; and a second drive signal causing the first coil stator assembly to apply a second torque to the magnetic rotor assembly; the first coil stator assembly configured to receive the a second coil stator assembly coupled to the first coil stator assembly such that operation of the first coil stator assembly is coupled to operation of the second coil stator assembly; a third drive signal causing the second coil stator assembly to apply a third torque to the magnetic rotor assembly; and a fourth drive signal causing the second coil stator assembly to apply a fourth torque to the magnetic rotor assembly. the second coil stator assembly configured to receive 1. An electric drive system for a vehicle, comprising: the first torque and the third torque cooperate to produce a first movement of the electric drive system relative to the vehicle chassis; the second torque and the fourth torque cooperate to produce a second movement of the electric drive system relative to the vehicle chassis; the first torque, the second torque, the third torque, and the fourth torque cooperate to produce the first motion and the second motion; The electric drive system.

2. A first operation of the electric drive system is rotation of the magnetic rotor assembly; The electric drive system of claim 1 , wherein the second movement of the electric drive system is a translational movement of the magnetic rotor assembly, the first coil stator assembly, and the second coil stator assembly.

3. An electric drive system as described in claim 1, wherein the first coil stator assembly is coupled to the second coil stator assembly such that rotation of the first coil stator assembly in a first direction causes rotation of the second coil stator assembly in a second direction opposite to the first direction.

4. An electric drive system as described in claim 1, further comprising a multi-bar linkage mechanism coupled to the first coil stator assembly and the second coil stator assembly such that operation of the first coil stator assembly is coupled to operation of the second coil stator assembly.

5. An electric drive system as described in claim 4, wherein the multi-bar link mechanism comprises a link mechanism having at least one of a crescent shape or a straight shape.

6. An electric drive system as described in claim 4, wherein the multi-bar linkage mechanism causes translational movement of the magnetic rotor assembly, the first coil stator assembly and the second coil stator assembly along a determined path.

7. An electric drive system as described in claim 6, wherein the determined path is at least one of a straight path or a curved path.

8. An electric drive system as described in claim 1, further comprising at least one of an elbow gear or pulley coupled to the first coil stator assembly and the second coil stator assembly such that operation of the first coil stator assembly is coupled to operation of the second coil stator assembly.

9. The method of claim 8, further comprising: providing a support structure coupled to the first coil stator assembly and the second coil stator assembly; The electric drive system of claim 1 , wherein the support structure is configured for attachment to a suspension of a vehicle.

10. The magnetic rotor assembly defining an axis of rotation; the electric drive system is a first torque link directly coupled to the first coil stator assembly; a second torque link directly coupled to the second coil stator assembly; a crankshaft coupled to the first torque link and the second torque link and parallel to the rotation axis; Furthermore, the crankshaft, the first torque link, and the second torque link are configured to couple operation of the first coil stator assembly to operation of the second coil stator assembly; The electric drive system of claim 1 , wherein the crankshaft is configured for translational movement relative to the vehicle chassis.

11. A torque link for coupling the operation of the first coil stator assembly to the operation of the second coil stator assembly and for limiting the range of rotation of each of the first coil stator assembly and the second coil stator assembly; a connector electrically coupled to the first coil stator assembly and the second coil stator assembly, the connector configured to deliver the first drive signal and the second drive signal to the first coil stator assembly and deliver the third drive signal and the fourth drive signal to the second coil stator assembly; The electric drive system of claim 1 further comprising:

12. A chassis; a plurality of wheel assemblies coupled to the chassis; Equipped with A vehicle, wherein at least one wheel assembly of the plurality of wheel assemblies comprises the electric drive system of claim 1 .

13. A magnetic rotor assembly configured to rotate about an axis of rotation; a first coil stator assembly; a second coil stator assembly; and a first torque link directly coupled to the first coil stator assembly; a second torque link directly coupled to the second coil stator assembly; a crankshaft coupled to the first torque link and the second torque link and parallel to the rotation axis; An electric drive system comprising: the crankshaft, the first torque link, and the second torque link couple the first coil stator assembly and the second coil stator assembly to one another so as to couple operation of the first coil stator assembly to operation of the second coil stator assembly; The electric drive system, wherein the crankshaft is configured for translational movement relative to a vehicle chassis.

14. An electric drive system as described in claim 13, wherein rotation of the first coil stator assembly in a first direction causes rotation of the second coil stator assembly in a second direction opposite to the first direction.

15. A first crank arm coupled to the first torque link and directly coupled to the crankshaft; a second crank arm coupled to the second torque link and directly coupled to the crankshaft; The electric drive system of claim 13 further comprising:

16. The method of claim 1, wherein the first torque link and the second torque link limit the range of rotation of the first coil stator assembly and the second coil stator assembly, respectively; 14. The electric drive system of claim 13, further comprising a connector electrically coupled to the first coil stator assembly and the second coil stator assembly and configured to deliver respective drive signals to the first coil stator assembly and the second coil stator assembly.

17. A chassis; a plurality of wheel assemblies coupled to the chassis; Equipped with 14. A vehicle, wherein at least one wheel assembly of the plurality of wheel assemblies comprises the electric drive system of claim 13.

18. A magnetic rotor assembly; a first coil stator assembly configured to receive a first drive signal and to impart a first torque to the magnetic rotor assembly in response to the first drive signal; a second coil stator assembly configured to receive a second drive signal and to impart a second torque to the magnetic rotor assembly in response to the second drive signal; a torque link coupled to the first coil stator assembly and the second coil stator assembly, the torque link coupling movement of the first coil stator assembly to movement of the second coil stator assembly and limiting the range of rotation of each of the first coil stator assembly and the second coil stator assembly; a connector electrically coupled to the first coil stator assembly and the second coil stator assembly for delivering the first drive signal to the first coil stator assembly and the second drive signal to the second coil stator assembly; An electric drive system comprising:

19. An electric drive system as described in claim 18, wherein rotation of the first coil stator assembly in a first direction causes rotation of the second coil stator assembly in a second direction opposite to the first direction.

20. A chassis; a plurality of wheel assemblies coupled to the chassis; Equipped with 20. A vehicle, wherein at least one wheel assembly of the plurality of wheel assemblies comprises the electric drive system of claim 18.

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