depicts a partial zoom-in cross-sectional view of the hammer; and

FIG. 18 depicts a partial exploded view of the motor 500 relative to the main housing 602.

Throughout this specification and figures like reference numbers identify like elements.

DETAILED DESCRIPTION

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide an explanation of various embodiments of the present teachings.

FIG. 1 depicts a perspective view of an electric mower 10, according to an embodiment. FIG. 2 depicts a side view of an electric mower 10 with a translucent main body 12, according to an embodiment. As shown in FIGS. 1 and 2, the electric mower 10 includes a main body 12 having a main deck 52 and a motor housing 50. The electric mower 10 further includes one or more blades 14 rotatably supported in a cavity 16 defined below the main deck 52, a pair of front wheels 18 supported by the main body 12, a pair of rear wheels 20 supported by the main body 12, and a handle 22 extending rearwardly from the main body 12. A grass collection bag 54 is supported on a rear side of the main body 12 below the handle 22.

In an embodiment, an outer-rotor brushless DC (BLDC) motor 500 coupled to a rotor shaft 340 is mounted in the motor housing 50 of the main body 12 above the main deck 52 for rotatably driving the one or more blades 14. The motor 500 may be arranged to drive the blades 14 by a direct drive mechanism (i.e., connecting the blade 14 directly to the rotor shaft 340). Alternatively, motor 400 may drive the blades 14 via a transmission mechanism including transfer gears, a transfer belt, and/or other speed and/or torque reduction and transmission components.

The handle 22 is provided with a pair of side rods 24 extending from either side end of the rear part of the main body 12 on two sides of the grass collection bag 54, and a cross rod 26 extending between the rear ends of the side rods 24. The cross rod 26 of the handle 22 is provided with a lever 28 for operating the BLDC motor 500.

In an embodiment, a battery cage 30 is disposed above the motor housing 50 for receiving a removable tool battery pack 32 therein. In an embodiment, the battery pack 32 may be a sliding power tool type battery pack having a 60V, 80V, 100V, or 120V maximum voltage. U.S. Pat. No. 8,573,324, which is hereby incorporated by reference in its entirety, provides an example of a sliding power tool battery pack that slidingly couples to a power tool. The battery cage 30 includes an angular opening sized to receive the battery pack 32 therein at an angle of, for example, 15 to 45 degrees relative to a plane of the main deck 52. In an embodiment, the battery pack 32 is positioned so as to intersect an axis of the rotor shaft 340.

In an embodiment, a power module 40 is disposed in the main body 12 within or adjacent the motor housing 50. The power module 40 includes a series of power switches configured as a three-phase inverter circuit for regulating supply of power from the battery pack to the motor 500. In an embodiment, a controller (not shown) is also disposed within the main body, as a part of the power module 40 or separately thereof, for controlling the switching operation of the power switches. Controller controls the power switches based on the position of the lever 28 to control the average voltage supplied from the battery pack to the motor 500.

In an embodiment, the motor 500 is supported within the motor housing 50 in a way that all components of the motor 500 are positioned above the plane of the main deck 52. Additionally, motor housing 50 is provided with two oppositely arranged exhaust vents 56 disposed above the main deck 52 arranged to expel air away from the motor 500 in a direction radial to the motor shaft 340 above the main deck 52.

The motor 500 features are described here in detail.

FIGS. 3A and 3B depict front and back perspective views of the BLDC motor 500, according to an embodiment. In an embodiment, motor 500 includes a first end cap 100, also referred to herein as a deck plate or a motor plate, and a second end cap 200, also referred to herein as a motor cup or stator mount. In an embodiment, the first end cap 100 is secured to the main deck 52 of the main body 12 by any method known to one skilled in the art. Similarly, the first end cap 100 and the second end cap 200 are coupled to one another by any method known to one skilled in the art. Such known methods include, but are not limited to, fasteners, adhesive, a tongue and groove assembly, friction-fitting, press-fitting, etc.

In an embodiment, the first end cap 100 includes a center opening 126 through which the rotor shaft 340 extends outwardly and one or more radial exhaust ports 124A and 124B arranged circumferentially on opposite sides of the first end cap 100. The second end cap 200 similarly includes a center opening 210 through which one or more control signal cables (not shown) are received, and a series of openings 220 and 222 disposed at a distance around the center opening 210. In an embodiment, stator terminals 440 to the power module 40 pass through one or more of the openings 220. These features will be described later in detail.

In an embodiment, inlet openings 222 are air inlets align with one or more air inlets (not shown) of the motor housing 50 that receive incoming cooling air from the outside environment. In an embodiment, radial exhaust ports 124A and 124B align with exhaust vents 56 of the motor housing 50 to allow expulsion of hot air away from the motor 500 above the main deck 52 and in a radial direction parallel to the plane of the main deck 52. This arrangement substantially isolates airflow for cooling the motor 500 components from the cavity 16 below the main deck 52. This reduces ingress of contaminated air including dust and grass into the motor 500. This also ensures that the airflow generates by the blade 14 within the cavity 16 is unimpeded by the airflow for cooling the motor 400.

FIGS. 4A and 4B depict front and back exploded views showing the components of BLDC motor 500, according to an embodiment. FIG. 5 depicts a cross-sectional view of the outer-rotor brushless motor 500, according to an embodiment. As shown in these figures, in addition to the first end cap 100 and the second end cap 200, the BLDC motor 500 includes a rotor assembly 300, a stator assembly 400, and the rotor shaft 340. In an embodiment, the first and second end caps 100 and 200 are secured to one another via fasteners 110 or other means to substantially contain and encapsulate the rotor assembly 300 and stator assembly 400 components. These features are described herein in detail.

In an embodiment, stator assembly 400 is provided as an inner stator including a stator lamination stack 410 having a ring-shaped stator core 402 and a plurality of stator teeth radially projecting outwardly from the stator core with slots formed therebetween. Stator windings 420 are wound around the stator teeth defining the phases of the BLDC motor 500. In an embodiment, where the BLDC motor 500 is a three-phase motor includes 12 stator windings 420, the stator will constitute three groups of four stator windings 420 connected together on or around the stator core. The stator windings 420 within each group of stator windings 420 may be electrically coupled together in a series of a parallel connection, and the three groups of windings may be electrically wired together in a wye or a delta configuration. In an embodiment, stator assembly 400 can further include one or more end insulators covering end surfaces of the stator lamination stack 410 to electrically insulate the stator windings 420 from the stator lamination stack 410.

In an embodiment, stator lamination stack 410 has a thickness of approximately 8-14 mm, preferably approximately 10-12 mm, and a diameter of approximately 100-130 mm, preferably approximately 110-115 mm. Thus, in an embodiment, the stator lamination stack has a diameter to thickness ratio of approximately 8-12, preferably approximately 9-11, in an example approximately 10. In an embodiment, this ratio optimizes the motor for high power/high torque applications such as a lawn mower. In an exemplary embodiment, the motor 500 has a maximum output speed of approximately 3,000 rpm, but a maximum power output of at least 1,100 watts, more preferably at least 1,200 watts, in an example approximately 1300 watts, suitable for high power/high torque applications.

In an embodiment, stator assembly 400 is secured, axially and radially, to the second end cap 200. The second end cap 200 is thus also referred to in this disclose as a stator mount. In an embodiment, ring-shaped stator core 402 of the stator assembly 400 is mounted and secured to an inner annular portion of the second end cap 200, as discussed later in detail.

In an embodiment, rotor assembly 300 is provided as an outer rotor including an inner annular member 322 and an outer annular core 320. Inner annular member 322 includes an inner through-hole that is securely mounted over the rotor shaft 340 by press-fitting or other known means. Outer annular core 320 is provided with a larger diameter than the stator assembly 400 so as to circumferentially surround the stator assembly 400 with a small airgap therebetween. Outer annular core 320 supports one or more permeant magnets (discussed below) that magnetically interact with the stator windings 420, causing rotation of the rotor assembly 300 around the stator assembly 400 when the stator windings are sequentially energized. Extending substantially radially or angularly between the inner annular member 322 and the outer annular core 320 are a series of radial blades 326 that form a fan arranged to generate airflow for cooling the motor 500 components, particularly the stator windings 440, as the rotor assembly 300 rotates. In particular, radial blades 326 are contained on their outer periphery by the annular core 320, thus forming an axial fan that directs air parallel to the axis of the rotor shaft 340. As will be described later in detail, first end cap 100 is provided with features to redirect the air generated by the axial fan in a radial direction.

In an embodiment, rotation of the rotor assembly 300 causes rotation of the rotor shaft 340 around its center longitudinal axis. In an embodiment, rotor shaft 340 is axially secured to the first and second end caps 100 and 200 via front and rear bearings 130 and 230, respectively. Front and rear bearing 130 and 230 provide axial and radial support for the rotor shaft 340, and subsequently for the entire rotor assembly 300, with respect to the first and second end caps 100 and 200, and subsequently with respect to the stator assembly 400. This arrangement ensures that the rotor outer annular core 320 is securely positioned around the stator assembly 400 with an airgap in between.

Referring now to FIGS. 6A-6E, and with continued reference to FIGS. 4A-5, details of the outer rotor assembly 300 and its assembly process are described herein, according to an embodiment.

FIG. 6A depicts a partial perspective view of the rotor assembly 300 including inner annular member 322, outer annular core 320, and radial blades 326. In an embodiment, between approximately four to sixteen radial blades 32, more preferably between six to fourteen radial blades, and even more preferably between eight to twelve radial blades, are provided. Each radial blade 326 can extend from an exterior portion of the inner annular member 322 to an interior portion 324 of the outer annular core 320. Interior portion 324 of the outer annular core 320 may include an inwardly-projecting rim having curved portions that mate with radial ends of the radial blades 326. The radial blades 326 can be placed at angles relative to a plane defined by the outer annular core 320 and the inner annular member 322. The angular arrangement of the radial blades 326 forms openings 328 between adjacent radial blades 326, through which airflow is generated and passed towards the first end cap 100. The geometry of the radial blades 326 can be in an airfoil shape to improve an overall efficiency of the moving air.

FIG. 6B depicts a perspective view of a laminated back iron ring 310, according to an embodiment. FIG. 6C depicts a perspective view of the laminated back iron ring 310, with permanent magnets 314 mounted on an inner surface thereof. In an embodiment, laminated back iron ring 310 is a ring-shaped lamination stack made of steel or other conductive material mounted within the outer annular core 320 of the rotor assembly 300 to support permanent magnets 314. The laminated back iron ring 310 can include magnet pockets 312 for holding the permanent magnets 314. In an embodiment, the number of the magnet pockets 312 can correspond to the number of the permanent magnets 314. In an embodiment, there may be between four to sixteen permanent magnets 314, more preferably between six to twelve permanent magnets 314, and even more preferably between eight to ten permanent magnets 314. The number of permanent magnets 314 is determined as number of poles and slots of the motor 500.

In an embodiment, each magnet pocket 312 can be formed into a peripherally elongated rectangular shape. In an example, each magnet pocket 312 may also be curved to match the curvature of the laminated back iron ring 310. Each of the permanent magnets 314 inserted into the corresponding magnet pocket 312 can be a sintered neodymium magnet, which is formed into a shape corresponding to the magnet pocket 312. Furthermore, the permanent magnets 314 are magnetized so that the magnets adjacent to each other have poles reverse to each other.

As shown in FIGS. 6A-6C, the inner surface of the outer circular member 324 can include a design to receive the laminated back iron ring 310. To this end, in an embodiment, the inner surface of the outer circular member 324 can include protrusions 332 that can correspond to grooves 319 on the laminated back iron ring 310. The interior portion 324 of the outer annular core 320 provides a platform for mounting and placement of the lamination back iron ring 310.

In an embodiment, as shown in FIG. 6D, the laminated back iron ring 310 and the permanent magnets 314 are at least partially encapsulated by an overmold layer 316 including resin or plastic material via an overmold or insert-mold process. In an embodiment, the overmold layer 316 substantially covers the permanent magnets 314 and forms molded-in airflow reliefs 318 between the respective magnets 314.

FIG. 6E depicts a perspective view of the outer rotor assembly 300 including the overmolded laminated back iron ring 310 of FIG. 6D, according to an embodiment. In an embodiment, the laminated back iron ring 310 having the permanent magnets 314 and being, at least, partially encapsulated by overmold layer 316 is slip-fitted to the outer annular core 320. In an embodiment, the protrusions 332 of the outer annular core 320 are aligned with the grooves 319 of the laminated back iron ring 310 and the laminated back iron ring 310 is received into the outer annular core 320.

In an embodiment, the laminated back iron ring 310 is secured to the outer annular core 320 by any known methods, such as by an adhesive to form the rotor assembly 300. In an embodiment, the laminated back iron ring 310 is first inserted into the outer annular core 320 and then the permanent magnets 314 are secured into the magnet pockets 312 by any known methods, such as by an adhesive. The overmold layer 316 may then be applied to the laminated back iron ring 310 having the permanent magnets 314 to form the rotor assembly 300.

FIG. 6F depicts a perspective view of the rotor assembly 300 mounted on the rotor shaft 340, according to an embodiment. As previously discussed, in an embodiment, inner through-hole 330 formed within the inner annular member 322 of the rotor assembly 300 is press-fitted on the rotor shaft 340. The rotor shaft 340 is thus axially, radially, and rotationally secured to the rotor assembly 300. As also previously discussed, rotor shaft 340 is further secured, axially and radially but not rotationally, to first end cap 100 and the second end cap 200 via front and rear bearings 130 and 230, respectively.

This arrangement provides an outer-rotor assembly having permanent magnets disposed around the outer circumference of a stator assembly, but also coupled to a central rotor shaft rotatably received within the stator assembly. This arrangement also integrates fan blades forming an axial fan for cooling the motor into the outer rotor assembly structure, ridding the motor of a separate fan structure.

In an embodiment, the rotor laminated back iron ring 310 has a diameter of approximately 120-150 mm, preferably approximately 130-140 mm, in an example approximately 136 mm. The entire rotor assembly 300 including the outer annular core 320 has a diameter of approximately 130-160 mm, preferably approximately 140-150 mm, in an example approximately 145 mm. In an embodiment, the rotor laminated back iron ring 310 has approximately the same thickness as the stator lamination stack 410.

Referring now to FIGS. 7A, 7B and 7C, and with continued reference to FIGS. 4A-5, the second end cap 200 is described herein in detail.

FIGS. 7A and 7B depict front and back perspective views of second end cap 200, according to an embodiment. FIG. 7C depicts a zoom-in cross-sectional view of the second end cap 200.

In an embodiment, second end cap 200 includes an outer annular body 202, an inner annular body 206 forming the center opening 210, and a conical or dome shaped main body 204 extending between the inner annular body 206 and the outer annular body 202. In an embodiment, front peripheral edge 208 of the outer annular body 202 is disposed to mate with the first end cap 200, as discussed later.

In an embodiment, center opening 210 of the inner annular body 206 forms a pocket 240 facing the first end cap 200 that securely supports the rear bearing 230 of the rotor shaft 340 therein to axially and radially support the rotor shaft 340 with respect to the second end cap 200. Additionally, pocket 240 houses a sense magnet ring 250 including a series of magnets is mounted on a distal end of the rotor shaft 340 rearwardly of the rear bearing 230. Moreover, pocket 240 houses and supports a positional sensor board 260 including a series of positional sensors (e.g., Hall sensors) in close proximity to and facing the sense magnet ring 250. The positional sensor board 260 is oriented on a plane substantially parallel to the longitudinal axis of the rotor shaft 340.

In an embodiment, pocket 240 includes a bearing pocket 242 at an end of the pocket 240 closest to the second end cap 200. The bearing pocket 242 (i.e., first portion of the inner annular body 206) has a first diameter sized to form-fittingly receive the rear bearing 230 of the rotor shaft 340 therein.

In an embodiment, the pocket 240 further includes a sense magnet pocket 244 disposed rearward of the bearing pocket 242 with respect to the second end cap 200. The sense magnet pocket 244 (i.e., third portion of the inner annular body 206) has a second diameter smaller than the first diameter, sized to freely receive and house the sense magnet ring 250 therein. In an embodiment, radial rim 246 formed between the bearing pocket 242 and the sense magnet pocket 244 forms as an axial stop for the rear bearing 230.

In an embodiment, the pocket 240 further includes a positional sensor board pocket 248 (i.e., second portion of the inner annular body 206) disposed rearward of the sense magnet pocket 244 with a third diameter smaller than the first and second diameters. In an embodiment, positional sensor board pocket 248 is sized to form-fittingly receive the positional sensor board 260 therein, with magnetic (hall) sensors 262 in close proximity to the sense magnet ring 250 at a distance of, for example, 0.5 to 3 mm, preferably 0.2-2 mm, and approximately 1 mm. The magnetic sensors 262 detect a magnetic field generated by the sense magnet ring 250 magnets to detect a rotatory position of the rotor shaft 340. In an embodiment, a radial rim 247 formed between the positional sensor board pocket 248 and an inner wall 249 of center opening 210 forms an axial stop for the positional sensor board 260. In an embodiment, positional sensor board 260 may be fastened to the radial rim 247 or the side walls of the positional sensor board pocket 248 via, for example, screws or other fastening means. Communication signals from the positional sensor board 260 may be passed through the center opening 210 for communication with the controller (not shown).

In an embodiment, the bearing pocket 240 protrudes inwardly towards the stator assembly 400 from the second end cap 200, with at least the bearing pocket 242 protruding axially into the inner opening of the ring-shaped stator core 402 of the stator assembly 400. This arrangement allows the rear bearing 230 to sit within the inner opening of the ring-shaped stator core 402 in-line with the stator lamination stack 410 along the same radial plane. Further, the sense magnet ring 250 is in-line with at least a portion of the stator windings 420 along the same radial plane. The arrangement according to this embodiment reduces the axial length of the BLDC motor 500 and flattens the overall envelope.

In an embodiment, one or more openings 220 are disposed in the main body 204 at a first radius around the center opening 210 through which the stator terminals 440 (i.e., for receiving U, V, W phase power lines from the power module 40) are received. In an embodiment, the stator terminals 440 project slightly out of the openings 220 to ease wrapping or fusing of power lines to the terminals 440. In an embodiment, air inlets 222 are disposed in the main body 204 along a second radius greater than the first radius around the center opening 210 for receiving incoming cooling air into the second end cap 200 for airflow generated by the motor fan.

In an embodiment, as briefly discussed above, the inner annular portion 206 of the second end cap 200 structurally, i.e., radially and axially, supports the stator assembly 400. In an embodiment, the ring-shaped stator core 402 is sized to be mounted around the inner annular portion 206 of the second end cap 200, with the stator lamination stack 410 being disposed circumferentially around the bearing pocket 242. This structure ensures that the stator assembly 400 is securely piloted within the second end cap 200 with high precision.

In power appliances such electric mower 10 utilizing the motor 500 described herein, the rotor assembly 300 can be seen deflecting drastically upon high impact resulting from contact between the mower blades 14 and a hard object such as a rock or metal object, particularly ingress of such hard object within the blades 14. In some instances, rotor assembly 300 can be seen pivoting around an axis that is perpendicular to the general axis of the motor 500 to deflect upwardly in the direction of the second end cap 200. In an embodiment, the deviation of the rotor shaft 340 from the longitudinal axis of the motor 500 causes the rotor assembly 300 to pivot around an axis perpendicular to the axis of the motor 500, one side of the rotor assembly 300 making contact with the stator assembly 400 and the second end cap 200. Any contact between the rotor assembly 300 in its rotating state and the non-rotating parts of the motor 500 including the stator assembly 400 and the second end cap 200 can cause severe damage to the motor 500 components.

To limit the deflection of the rotor assembly 300 in the event of such contact or ingress of hard objects with or into the mower blades 14, according to an embodiment of the invention, the second end cap 200 is provided with one or more deflection limiting members 270, as shown in the perspective view of FIG. 8A. In an embodiment, deflection limiting members 270 may be made of flexible and/or elastically resilient material such as plastic, rubber, etc. In an embodiment, deflection limiting members 270 may be secured to an inner surface of the main body 204 of the second end cap 200 bordering the outer annular body 202. In an embodiment, deflection limiting members 270 may be provided as a series of discrete segments provided at a distance from one another, as shown in FIG. 8A, or as a one-piece ring sized to be received within the outer annular body 202. In an embodiment, deflection limiting members 270 may be provided as integral ribs projecting from the main body 204 and/or the outer annular body 202 of the second end cap 200, or as separate pieces assembled into the second end cap 200.

In an embodiment, deflection limiting members 270 are provided with a height 272 (in the axis direction of the motor 500) that is smaller than the distance between the rotor assembly 300 and the main body 204 of the second end cap 200. In an embodiment, the height 272 of deflection limiting members 270 is sized so that the rotor assembly 300 does not contact the deflection limiting members 270 during normal operation and with a normal level of vibration and movement, but is prevented by deflection limiting members 270 from pivoting drastically so as to come into contact with the stator assembly 400.

In an embodiment, a thickness 272 (in the radial direction of the motor 500) of the deflection limiting members 270 is sized to come into contact with the rotor assembly 300, i.e., peripheral end of the laminated back iron ring 310 or the overmold layer 316, but not with the stator assembly 400. In an embodiment, deflection limiting members 270 are disposed along a ring having a diameter that is greater than the diameter of the stator assembly 400 but approximately corresponds to the diameter of the laminated back iron ring 310 of the rotor assembly 300.

In the event of high impact resulting from contact or ingress of hard objects described above, the upward deflection of the rotor assembly 300 may also at times make contact with and damage the positional sensor board 260. This is particularly due to the small air gap that is maintained between the positional sensor board 260 and the sense magnet ring 250 for accurate sensing of the angular position of the rotor assembly 300.

To absorb this impact and protect the positional sensor board 260 from damage, according to embodiment, an impact absorbing member 280 is provided, as depicted in the partial cross-sectional view of FIG. 8B. In an embodiment, impact absorbing member 280 is received within sensor board pocket 248. Impact absorbing member 280 may be fastened to the radial rim 247 or the side walls of the positional sensor board pocket 248 via, for example, adhesive, screws or other fastening mechanism. In an embodiment, positional sensor board 260 is in turn secured to the impact absorbing member 280 via, for example, an adhesive, screws, or other fastening mechanism. In an embodiment, impact absorbing member 280 may be made of flexible or resiliently elastic material such as dense foam, rubber, etc. In an embodiment, impact absorbing member 280 may be provided with the sufficient thickness to effectively absorb the force of an impact upon the positional sensor board 260 by the rotor shaft 340 and/or the sense magnet ring 250, while maintaining proper airgap between the sense magnet ring 250 and the positional sensor board 260. In an embodiment, impact absorbing member 280 may be 1-3 mm in thickness. In an embodiment, impact absorbing member 280 may be disc-shaped or ring-shaped with an outer diameter that is substantially equivalent to or greater than the positional sensor board 260.

In an embodiment, the impact absorbing member may be a spring element 282 provided to absorb the impact on the positional sensor board 260, as depicted in the partial cross-sectional view of FIG. 8C. In an embodiment, spring member 282 may be a wave spring, though other types of spring such as a Belleville washer, disc spring, compression spring, torsion spring, etc. may alternatively be utilized. In an embodiment, spring member 282 is sized to be received within the sensor board pocket 248 and secured to the radial rim 247 or the side walls of the positional sensor board pocket 248 via, for example, adhesive, screws or other fastening mechanism. In an embodiment, positional sensor board 260 is in turn secured to the impact absorbing member 280 via, for example, an adhesive, screws, or other fastening mechanism. In an embodiment, spring member 282 may be provided with the sufficient thickness to effectively absorb the force of an impact upon the positional sensor board 260 by the rotor shaft 340 and/or the sense magnet ring 250, while maintaining proper airgap between the sense magnet ring 250 and the positional sensor board 260. In an embodiment, spring member 280 may have a thickness of 1-3 mm.

FIG. 8D depicts a perspective view of a wave spring used as the spring member 282, according to an embodiment.

The first end cap 100 is described herein in detail with reference to FIGS. 9A-11B, and with continued reference to FIGS. 4A-5, according to an embodiment.

FIGS. 9A and 9B depict front and back perspective views of the first end cap 100, according to an embodiment. FIG. 10A respectively depict a top perspective view and a top horizontal cross-sectional view of the first end cap 100 along the y-z plane, according to an embodiment. FIGS. 11A and 11B respectively depict a side perspective view and a side vertical cross-sectional view of the first end cap 100, according to an embodiment.

In an embodiment, as previously discussed, rotor shaft 340 passes through central opening 126 of the first end cap 100 to protrude into the main deck 52 of the electric mower 10 for driving the blades 14. Moreover, the central opening 126 includes a bearing pocket 128 sized to form-fittingly and securely receive the front bearing 130 of the rotor shaft 340. The front bearing 130 secures the rotor assembly 300 with respect to the first end cap 100 axially and radially, while allowing free rotation of the rotor assembly 300 within the first end cap 100.

Additionally, the first end cap 100 includes a radial back plate 120 facing the rotor assembly 300, an annular body 118 formed around the radial back plate 120, and a donut-shaped side plate 116 projecting outwardly around the annular body 118 along substantially the same plate as the radial back plate 120. A rear peripheral edge 117 of the annular body 118 comes to contact with front peripheral edge 208 of the second end cap 200 to substantially circumferentially enclose the rotor and stator assemblies 300 and 400.

In an embodiment, radial back plate 120 is disposed adjacent radial blades 326 that form the fan of the rotor assembly 300. The back plate 120 acts as a baffle for the fan, redirecting airflow generated by the fan to be expelled out of the exhaust ports 124A and 124B in a direction radial to the rotor shaft 340. In an embodiment, back plate 120 includes at least one sloped surface, for example, two sloped surfaces 120A and 120B, as shown in FIGS. 9B, 10B, and 11B. The two sloped surfaces 120A and 120B of the back plate 120 are each sloped with respect to a radial plane of the back plate 120 such that adjacent ends of the two slopes surfaces 120A and 120B are axially offset with respect to one another, forming two air gaps 123A and 123B therebetween. Each of the air gaps 123A and 123B extends from approximately the outer portion of the bearing pocket 128 to approximately an inner portion of the rear peripheral edge 117 of the annular body 118. The air gaps 123A and 123B are formed parallel to the x-y plane in FIG. 9B, where the x axis designates the longitudinal axis of the motor shaft 340. The air gaps 123A and 123B extend laterally into the annular body 118, forming air channels that are in fluid communication with the radial exhaust ports 124A and 124B. Radial exhaust ports 124A and 12B are formed over the side plate 116. As airflow generated by the fan comes into contact with the back plate 120, the sloped surfaces 120A and 120B cause centrifugal circulation of the airflow within the first end cap 100. Air gaps 123A and 123B intercept the centrifugal circulation path of the airflow within the first end cap 100, causing the air to exit the first end cap 100 in a radial and/or lateral direction through the exhaust ports 124A and 124B. Arrangement of the exhaust ports 124A and 124B above the main deck 52 of the electric mower 10 ensures that hot air existing the motor 500 does not enter the cavity 16 of the mower 10. The two sloped surfaces 120A and 120B of the back plate 120 can form baffles that can provide a cyclonic path for the airflow generated by the radial blades 326 to be directed towards the two radial exhaust ports 124A and 124B.

In an embodiment, each of the sloped surfaces 120A and 120B is an inclined surface, which has a starting end adjacent to the radial blades 326 of the rotor assembly 300 and a terminal end adjacent to the each of the corresponding exhaust ports 124A and 124B.

In an embodiment, each of the sloped surfaces 120A and 120B extend from the starting end to the terminating end along the circumferential direction with a substantially constant width from the starting end to the terminal end. Two connecting walls 122A and 122B connect the outer edge of each of the sloped surfaces 120A and 120B to the first end cap body. Each of the connecting walls 122A and 122B can extend from the starting end of its corresponding sloped surfaces 120A and 120B and to the terminating end of each of its corresponding sloped surfaces 120A and 120B.

In an embodiment, main deck 52 includes a corresponding through-hole that aligns with the central opening 126 for receiving the rotor shaft 340. In an embodiment, a series of screws are received through the cavity 16 of the main deck 52 through corresponding through-holes of the main deck 52 (not shown) and peripheral receptacles 125 of the first end cap 100. A series of slugs or threaded nuts 112 are provided on the side plate 116 of the first end cap 100 to securely receive the screws and fasten the first end cap 100 on top of the main deck 52. For this reason, the first end cap 100 is also referred to as the deck mount in this disclosure.

In an embodiment, the overall motor assembly 500 includes an envelope of approximately 140-180 mm, preferably approximately 150-170 mm, in an example approximately 160 mm, as defined by the diameter of the annular body 118 of the first end cap 110 and the diameter of the second end cap 200. Furthermore, the length of the more, as defined between the lower end of the first end cap 100 and the upper end of the second end cap 200, is approximately 60-100 mm, preferably approximately 70-90 mm, in an example approximately 80 mm. This approximately 2:1 ratio of the motor diameter to height provides for a high torque, high power, planar-shaped motor that can be flatly mounted on top of the main deck 52 of the mower 10.

Aspects of the stator assembly 400 are described herein in detail with reference to FIGS. 12A-14B, and with continued reference to FIGS. 4A-5, according to an embodiment.

FIGS. 12A and 12B depict perspective views stator assembly 400 with a stator collar 430 prior and after assembly onto the ring-shaped stator core 402 of the stator assembly 400, according to an embodiment. FIG. 13A depicts a perspective view of the stator assembly 400 including the stator windings 420, with the stator collar 430 mounted thereon, according to an embodiment. FIG. 13B depicts a perspective zoomed-in view of the stator assembly 400 showing a single stator terminal 440 of the stator collar 430, according to an embodiment. Additionally, FIGS. 14A and 14B depict side and top views of the stator assembly 400, respectively, according to an embodiment.

In an embodiment, stator teeth 406 extend radially from the stator core 402. Each of the stator teeth 406 is wound by a stator coil to form the stator windings 420. The stator coils can be separately wound on the stator teeth 406 or continuous wound on the stator teeth 406, in a series or parallel and delta or wye configuration, as discussed above. In an embodiment, each of the stator teeth 406 is substantially T-shaped.

In order to electrically isolate the stator coils from the stator lamination stack 410, the end insulators 412 may be provided. In an embodiment, end insulators are discrete components mounted on the ends of the stator lamination stack 410, or at least partially encapsulate the stator lamination stack 410 by a process, such as an overmold process. The end insulators 412 can be made from a material such as plastic or resin.

In an embodiment, stator collar 430 can include a substantially-cylindrical insulation carrier 432, which may be formed from plastic material. Additionally, the stator collar 430 can include a series of stator terminals 440, such as three stator terminals 440, mounted on the insulation carrier 432 and electrically insulated from each other by the insulation carrier 432. In an embodiment, each of the stator terminals 440 can be pressed into the stator collar 430. In an embodiment, the stator collar 430 includes a series of side openings with railings or channels 444 arranged parallel to the center axis of the stator collar 430 (and center axis of the motor 500) along the side openings. The stator terminals 440 include two side guides 446 that are slidingly received within the railings or channels 444 to affix the stator terminals 440 within the side openings of the stator collar 430.

In an embodiment, at least one of the end insulators 412 of the stator assembly 400 includes an inner annular rim 404 that supports mounting the stator collar 430 on the stator assembly 300. The insulating carrier 432 of the stator collar 430 is annular and can be fixed to or be placed inside or on the inner annular rim 404 of the end insulator 412. In an embodiment, end insulator 412 includes a central opening formed within the annular rim 404 with a larger diameter than central opening 411 of the stator lamination stack 410. This arrangement exposes a donut-shaped mounting platform 414 of the end surface of the stator lamination stack 410 facing the stator collar 430. A lower portion 434 of the insulating carrier 432 includes an outer diameter that is smaller than the outer diameter of the insulating carrier 432, sized to fit within the annular rim 404 and rest on top of the mounting platform 414 of the end surface of the stator lamination stack 410.

In an embodiment, end insulator 412 can also be provided with a series of tabs 416 projecting axially (in parallel to the longitudinal axis of the motor 500) from or adjacent to the annular rim 404. Stator collar 430 similarly includes recessed surfaces 448 that removably receive the tabs 416 for positioning and retention of the stator collar 430 over the end insulator 412. In an embodiment, the tabs 416 or the recessed surfaces 448 may include snaps 449 for improved retention of the stator collar 430 over the end insulator 412.

In an embodiment, end insulator 412 further includes a series of recessed surfaces 417 that extend radially through the annular rim 404 into the outer surface of the teeth of the end insulator 412. Stator collar 430 is similarly provided with a series of radial protrusions 447 that are removably received within the recessed surfaces 417. The recessed surfaces 417 and radial protrusions 447 may be provided with snaps or other known retention features for securing the stator collar 430 over the end insulator 412.

In an embodiment, this configuration of the stator assembly 300 and stator collar 430 allows the stator collar 430 to be interchangeable with another one that has different types and/or quantities of stator terminals. The stator collar 430 may include different solder points for the terminals, different junctions for the terminals, different weld connections for the terminals, or a different number of terminals (e.g., for a 6-phase controlled motor v. a 3-phase controlled motor). Different stator collars 430 may be chosen by a motor designer based on, for example, the thickness of stator winding wires and/or the number of turns of windings around each stator tooth, the series or parallel connections between stator windings in the same phase, the delta or wye connections between stator windings of different phases, etc. For example, the dual-tang configuration described above may be more suited for a motor design with relatively thick stator windings. Interchangeability of the stator collar