Patent Description:
When the topology of an electric machine uses permanent magnets, the magnet temperature should be controlled. Cooler magnets can lead to improved machine performance. In addition, maintaining magnets at cooler temperatures can reduce their risk of demagnetization. Because, in some conventional electric machines, the permanent magnets are positioned in the rotor assembly, cooling the magnets can be difficult. Some conventional methods of cooling electric machines can include circulating a coolant around a portion of an outer perimeter of the electric machine. Because the rotor assembly can be positioned radially inward from the outer perimeter of the machine, transmission of heat energy produced by the rotor assembly to the coolant can be difficult. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> each discloses a rotary electric machine provided with a cooling system.

<CIT> teaches a motor with an oil pump. The oil pump pumps up cooling oil collected at the bottom of a case, and jets the cooling oil from a jet nozzle provided in an outlet via a passage. The cooling oil splashes on a coil end, thereby cooling the coil end.

An example of an electrical machine module includes a housing defining a machine cavity. In some examples, an electric machine can be positioned within the machine cavity and can include a rotor hub coupled to rotor laminations. In some examples, the rotor hub can include opposing first and second axial ends and the rotor laminations can include at least one recess. In some examples, the recesses can be substantially aligned to define at least a portion of a plurality of coolant channels that can be in fluid communication with the machine cavity. In some examples, the rotor hub can include at least first and second rotor hub inlets in fluid communication with at least a portion of the coolant channels. In some examples, the first and the second rotor hub inlets can be located adjacent to the first and the second axial ends of the rotor hub, respectively. In some examples, the coolant channels in fluid communication with the first and the second rotor hub inlets are not the same coolant channels.

An electrical machine module according to the present invention is defined by claim <NUM>. The electrical machine module includes a housing at least partially defining a machine cavity. An electric machine is positioned substantially within the machine cavity, and it at least partially enclosed by the housing, and includes a rotor assembly including a rotor hub. The rotor assembly is operatively coupled to an output shaft, which includes at least one output shaft coolant channel and at least one output shaft coolant outlet in fluid communication with the output shaft coolant channel. The rotor assembly includes at least one magnet, a first axial end, and a second axial end. The first axial end opposes the second axial end. The rotor assembly includes a plurality of coolant channels extending from the first axial end to the second axial end, and the plurality of coolant channels in fluid communication with the machine cavity. At least one rotor hub channel is positioned through a portion of the rotor assembly so that the rotor hub channel is in fluid communication with the output shaft coolant outlet and the plurality of coolant channels. The rotor assembly includes a plurality of rotor laminations, wherein the plurality of coolant channels are defined between an inner diameter of the rotor laminations and an outer diameter of the rotor hub. The plurality of coolant channels are at least partially defined by recesses formed in the inner diameter of the rotor laminations. The recesses are arranged so that the coolant channels are in fluid communication with the cavity.

In some embodiments, at least a first rotor hub inlet can be positioned through a portion of the rotor assembly substantially adjacent to the first axial end and at least a second rotor hub inlet can be positioned through a portion of the rotor assembly substantially adjacent to the second axial end. In some embodiments, the first rotor hub inlet can be in fluid communication with at least a portion of the plurality of coolant channels and the second rotor hub inlet can be in fluid communication with at least a portion of the plurality of coolant channels. In some embodiments, the portion of the coolant channels that is in fluid communication with the first rotor hub inlet, the portion of the coolant channels that is in fluid communication with the second rotor hub inlet, and the portion of the coolant channels that is in fluid communication with the rotor hub channel are not the same coolant channels.

The invention is capable of other embodiments and of being practiced or of being carried out in various ways, as far as said embodiments or ways do not depart form the scope of the invention, which is defined by the appended claims.

The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications as far as they do not depart from the scope of the invention, which is defined by the appended claims. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the appended claims. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives as far as they fall within the scope of embodiments of the invention.

<FIG> illustrates an electric machine module <NUM>. The module <NUM> can include a module housing <NUM> comprising a sleeve member <NUM>, a first end cap <NUM>, and a second end cap <NUM>. An electric machine <NUM> can be housed within a machine cavity <NUM> at least partially defined by the sleeve member <NUM> and the end caps <NUM>, <NUM>. For example, the sleeve member <NUM> and the end caps <NUM>, <NUM> can be coupled via conventional fasteners (not shown), or another suitable coupling method, to enclose at least a portion of the electric machine <NUM> within the machine cavity <NUM>. The housing <NUM> can comprise a substantially cylindrical canister and a single end cap (not shown). Further, the module housing <NUM>, including the sleeve member <NUM> and the end caps <NUM>, <NUM>, can be fabricated from materials that can generally include thermally conductive properties, such as, but not limited to aluminum or other metals and materials capable of generally withstanding operating temperatures of the electric machine. The housing <NUM> can be fabricated using different methods including casting, molding, extruding, and other similar manufacturing methods.

The electric machine <NUM> can include a rotor <NUM>, a stator assembly <NUM>, including stator end turns <NUM>, and bearings <NUM>, and can be disposed about an output shaft <NUM>. As shown in <FIG>, the stator assembly <NUM> can substantially circumscribe the rotor <NUM>. The rotor assembly <NUM> also includes a rotor hub <NUM>.

The rotor assembly <NUM> is operatively coupled to the output shaft <NUM> so that the two elements can substantially synchronously move together. The output shaft <NUM> can comprise a plurality of splines (not shown) configured and arranged to engage a plurality of splines <NUM> on the rotor hub <NUM>. The engagement of the splines can at least partially lead to coupling of the rotor assembly <NUM> and the output shaft <NUM>. During operation of the electric machine <NUM>, when the output shaft splines are engaged with the rotor hub splines <NUM>, torque generated by the electric machine <NUM> can be transferred from the rotor assembly <NUM> to the output shaft <NUM>. The output shaft <NUM> can be operatively coupled to a positive stop (not shown) on the rotor hub <NUM> to transfer torque. The output shaft <NUM> can be operatively coupled to the positive stop on the rotor hub <NUM> using a bolt (not shown) or any other conventional fastener. The output shaft <NUM> can comprise a male-configured spline set or alternatively, the output shaft <NUM> can comprise a female-configured spline set.

The electric machine <NUM> can be, without limitation, an electric motor, such as a hybrid electric motor, an electric generator, or a vehicle alternator. The electric machine <NUM> can be a High Voltage Hairpin (HVH) electric motor or an interior permanent magnet electric motor for hybrid vehicle applications.

Components of the electric machine <NUM> such as, but not limited to, the rotor <NUM>, the stator assembly <NUM>, and the stator end turns <NUM> can generate heat during operation of the electric machine <NUM>. These components can be cooled to increase the performance and the lifespan of the electric machine <NUM>.

As shown in <FIG>, the sleeve member <NUM> can comprise a coolant jacket <NUM>. For example, the sleeve member <NUM> can include an inner wall <NUM> and an outer wall <NUM> and the coolant jacket <NUM> can be positioned substantially between the walls <NUM>, <NUM>. The coolant jacket <NUM> can substantially circumscribe at least a portion of the electric machine <NUM>. More specifically, the coolant jacket <NUM> can substantially circumscribe at least a portion of an outer diameter of the stator assembly <NUM>, including the stator end turns <NUM>.

The coolant jacket <NUM> can contain a coolant that can comprise transmission fluid, ethylene glycol, an ethylene glycol / water mixture, water, oil, motor oil, a mist, a gas, or another substance capable of receiving heat energy produced by the electric machine module <NUM>. The coolant jacket <NUM> can be in fluid communication with a coolant source (not shown) which can pressurize the coolant prior to or as it is being dispersed into the coolant jacket <NUM>, so that the pressurized coolant can circulate through the coolant jacket <NUM>.

The inner wall <NUM> can include coolant apertures <NUM> so that the coolant jacket <NUM> can be in fluid communication with the machine cavity <NUM>. The coolant apertures <NUM> can be positioned substantially adjacent to the stator end turns <NUM>. As the pressurized coolant circulates through the coolant jacket <NUM>, at least a portion of the coolant can exit the coolant jacket <NUM> through the coolant apertures <NUM> and enter the machine cavity <NUM>. The coolant can contact the stator end turns <NUM>, which can lead to at least partial cooling. After exiting the coolant apertures <NUM>, at least a portion of the coolant can flow through portions of the machine cavity <NUM> and can contact various module <NUM> elements, which can lead to at least partial cooling of the module <NUM>.

As shown in <FIG>, the rotor assembly <NUM> comprises a plurality of rotor laminations <NUM>. The rotor laminations <NUM> can comprise a plurality of generally annular-shaped structures configured and arranged to be coupled to at least a portion of the rotor hub <NUM>. The rotor laminations <NUM> can comprise other shapes that are capable of engaging the rotor hub <NUM> (e.g., so that the shapes of the two elements are substantially similar). Each of the rotor laminations comprise an inner diameter <NUM> and an outer diameter <NUM> and can be coupled together to form at least a portion of the rotor assembly <NUM>.

As shown in <FIG>, the rotor laminations <NUM> can comprise multiple elements. At least a portion of the laminations <NUM> can include a plurality of apertures <NUM> that are configured and arranged to support at least a portion of a plurality of magnets <NUM>. After assembling the laminations <NUM>, the apertures <NUM> can substantially align in a generally axial direction so that the magnets <NUM> can be positioned within the rotor assembly <NUM> in a substantially axial direction. Moreover, the magnets <NUM> can be disposed of within the rotor assembly so that at least a portion of the magnets are not substantially axially aligned. For example, the magnets <NUM> can be positioned so that some of the magnets <NUM> are positioned approximately two degrees apart (e.g., skewed).

The laminations <NUM> comprise a plurality of recesses <NUM>. The recesses <NUM> can be formed during rotor lamination <NUM> fabrication (e.g., stamping, molding, casting, etc.) and in other examples, the recesses <NUM> can be machined into the laminations <NUM> after fabrication to suit end user and/or manufacturer requirements. Referring to <FIG>, the recesses <NUM> are positioned along the inner diameter <NUM> of the laminations <NUM>. For example, the recesses can be arranged in a substantially regular pattern along the circumference of the inner diameter <NUM>. The recesses <NUM> can be arranged at substantially irregular intervals.

Additionally, at least a portion of the laminations <NUM> of the rotor assembly <NUM> can each comprise recesses <NUM> in substantially similar positions so that after assembly, the recesses <NUM> can substantially align to form at least a portion of at least one coolant channel <NUM>, as shown in <FIG>. With laminations <NUM> including a plurality of recesses <NUM>, more than one coolant channel <NUM> can be formed. For example, the rotor assembly <NUM> can be substantially assembled so that the inner diameter <NUM> of the laminations <NUM> is immediately adjacent to an outer diameter <NUM> of the rotor hub <NUM>. As a result, the coolant channels <NUM> can be substantially defined by the recesses <NUM> and the outer diameter <NUM> of the rotor hub <NUM>. After assembly of the rotor assembly <NUM>, the recesses <NUM> are configured and arranged so that the coolant channels <NUM> are in fluid communication with the machine cavity <NUM>. As described in more detail below, the coolant channels <NUM> can be configured and arranged to guide the coolant through the rotor assembly <NUM> and into the machine cavity <NUM> to aid in cooling some elements of the rotor assembly <NUM>, including the magnets <NUM>. Additionally, the coolant channels <NUM> can be substantially linear, or the rotor hub <NUM> and/or the laminations <NUM> can be configured and arranged so that at least a portion of the coolant channels <NUM> are substantially non-linear (i.e., skewed, helical, curved, etc.).

In addition to the coolant jacket <NUM> and the coolant apertures <NUM>, the coolant can be dispersed from a point generally radially central with respect to the electric machine module <NUM>. A coolant source (not shown) can be located either internal or adjacent to a output shaft <NUM> so that the coolant can flow either inside of or adjacent to the output shaft <NUM>. For example, the output shaft <NUM> can include at least one output shaft channel <NUM> and at least one output shaft coolant outlet <NUM> so that the coolant can flow through the channel <NUM> and at least a portion of the coolant can exit the output shaft channel <NUM> through the output shaft coolant outlet <NUM>. The output shaft coolant outlet <NUM> can comprise a plurality of output shaft coolant outlets <NUM>. Also, output shaft coolant outlets <NUM> can be positioned along the axial length of the output shaft <NUM> so that the coolant can be dispersed to different areas of the module <NUM>, including the bearings <NUM>.

As shown in <FIG>, an example is shown of at least one rotor hub channel <NUM>. The rotor hub <NUM> can include a plurality of rotor hub channels <NUM>. For example, the rotor hub channels <NUM> can be positioned within the rotor hub <NUM> and can be generally perpendicular to a horizontal axis of the output shaft <NUM>. For example, the rotor hub channel <NUM> can comprise a passageway which can extend from the outer diameter <NUM> of the rotor hub <NUM> to an inner diameter <NUM> of the rotor hub <NUM>, although the rotor hub channel <NUM> need not extend the entire radial length of the rotor hub <NUM>. The rotor hub channels <NUM> are in fluid communication with at least a portion of the output shaft coolant outlets <NUM>. Centrifugal force created by the movement of the operating rotor assembly <NUM> can cause at least some of the coolant to flow from the output shaft coolant outlets <NUM> radially outward through at least a portion of the rotor hub channels <NUM>.

At least a portion of the rotor hub channels <NUM> are in fluid communication with at least a portion of the coolant channels <NUM>. For example, as shown by the arrows in <FIG>, at least partially due to the centrifugal force, the coolant can flow radially outward through the rotor hub channels <NUM> and can enter at least a portion of the coolant channels <NUM>. After entering the coolant channels <NUM>, at least a portion of the coolant can flow in one of or both axial directions of the coolant channels <NUM>, as shown in <FIG>. For example, after entering at least a portion of the coolant channels <NUM>, the coolant can flow in the direction of both axial ends of the rotor assembly <NUM> and can then enter the machine cavity <NUM>. At least one of the axial ends of a portion of the coolant channels <NUM> can be substantially sealed so that coolant flows into the machine cavity <NUM> through only one axial end of the coolant channels <NUM>. An end ring <NUM> can be coupled to at least one of or both one of or both axial faces of the rotor assembly <NUM>. The end ring <NUM> can at least partially function to guide, urge, and/or direct coolant toward other elements of the module <NUM>, such as the stator end turns <NUM>. In some embodiments, the end ring <NUM> can comprise a balance ring, an agitator ring, a coolant guide, or other similar structure.

Moreover, after entering the machine cavity <NUM>, the coolant can circulate through portions of the machine cavity <NUM> where it can contact different elements of the module <NUM> to receive at least a portion of the heat energy produced, which can aid in cooling. Additionally, while flowing through the coolant channels <NUM>, the coolant can receive at least a portion of the heat energy produced by the magnets <NUM> and other elements of the rotor assembly <NUM>, which can lead to cooling of at least a portion of the rotor assembly <NUM>. For example, as the temperature around the magnets <NUM> is at least partially reduced, the electric machine <NUM> can operate at higher levels of performance. In addition, by extracting the heat from the magnets <NUM>, the propensity of demagnetization of the magnets <NUM> is at least partially reduced.

The rotor assembly <NUM>, including the coolant channels <NUM> can comprise different configurations. At least a portion of the coolant channels <NUM> can be fluidly connected to the machine cavity <NUM> via at least one rotor hub inlet <NUM>. By way of example only, as shown in <FIG> and <FIG>, the rotor hub inlet <NUM> can be positioned through a portion of the rotor hub <NUM> so that the at least a portion of the coolant in the machine cavity <NUM> that is proximal to the rotor hub <NUM> can enter at least a portion of the coolant channels <NUM> via the rotor hub inlets <NUM>.

The rotor hub inlets <NUM> can be positioned near the axial edges of the rotor hub <NUM>, as shown in <FIG> and <FIG>. Moreover, the rotor assembly <NUM> can be configured and arranged so that portions of the coolant can flow in substantially both axial directions. For example, the rotor hub <NUM> can comprise a plurality of rotor hub inlets <NUM> adjacent to axial sides of the rotor hub <NUM>. The rotor hub inlets <NUM> on the axial sides can be offset so that at least a portion of the rotor hub inlets <NUM> are in fluid communication with only one coolant channel <NUM> (e.g., one rotor hub inlet <NUM> per coolant channel <NUM>). Additionally, at least a portion of the coolant channels <NUM> can be substantially unidirectional. For example, at least one axial end of at least a portion of the coolant channels <NUM> can be substantially sealed so that any coolant entering the coolant channel <NUM> would only flow out of the channel <NUM> at the axial end opposite the sealed end. By way of example only, the end lamination <NUM> can be differently configured so that the coolant channel <NUM> does not extend through that lamination <NUM>. The balance ring <NUM> on the substantially sealed end can extend a radial distance to substantially seal the coolant channel <NUM>, as shown in <FIG>.

As a result, the coolant can circulate in at least two different axial directions. For example, a first portion of the coolant can enter at least one rotor hub inlet <NUM> on a first axial side (e.g., either the left side or the right side of the rotor hub <NUM>) adjacent to where the coolant channel <NUM> is sealed. As a result, due at least in part to centrifugal force, the coolant can circulate through the coolant channel <NUM> toward a second side of the rotor hub <NUM> (i.e., the opposite side of the rotor hub <NUM>) and then enter the machine cavity <NUM>, as shown by the arrows in <FIG>. Moreover, another portion of coolant can enter at least one rotor hub inlet <NUM> on the second axial side, which is in fluid communication with at least one different coolant channel <NUM> adjacent to where the coolant channel <NUM> is sealed. As a result, due at least in part to centrifugal force, the coolant can circulate through the coolant channel <NUM> toward the first side of the rotor hub <NUM> and then enter the machine cavity <NUM>, as shown by the arrows in <FIG>. Accordingly, at least a portion of the coolant can flow through different coolant channels <NUM> in substantially opposite directions. This bidirectional flow can at least partially increase heat energy transfer from the magnets <NUM> and other portions of the rotor assembly <NUM>. By passing the coolant in both directions, the average magnet temperature on each end of the rotor assembly <NUM> can be maintained at a generally comparable level.

The rotor hub <NUM> and/or the rotor assembly <NUM> can be configured and arranged to permit and/or enhance coolant flow through the rotor hub inlets <NUM>. For example, an annular flange <NUM> can be positioned substantially at or adjacent to the axial edges of the rotor hub <NUM>. The flange <NUM> can be machined into the rotor hub <NUM> and in other embodiments the flange <NUM> can be coupled to the rotor hub <NUM>, or the rotor hub <NUM> can be formed so that the flange <NUM> is substantially integral with the rotor hub <NUM>.

The flange <NUM> can be configured and arranged to guide coolant toward the rotor hub inlets <NUM>. For example, a portion of the coolant in the machine cavity <NUM> that originates from the coolant apertures <NUM>, the coolant channels <NUM>, and/or any other source, can be forced to flow along an interior surface of the rotor hub <NUM>, due to centrifugal force. As a result, at least a portion of the coolant can flow through the rotor hub inlets <NUM>, as previously mentioned. However, the flange <NUM> can retain at least a portion of the remaining coolant that does not readily flow through the rotor hub inlets <NUM> so that more coolant can be directed through the rotor hub inlets <NUM> relative to examples functioning without the flange <NUM>.

Also, the rotor hub <NUM> and/or the rotor assembly <NUM> can comprise other configurations to at least partially enhance coolant entry into the rotor hub inlets <NUM>. At least a portion of rotor hub <NUM> immediately adjacent to the rotor hub inlet <NUM> can be configured and arranged to guide, urge, and/or direct coolant through the rotor hub inlet <NUM> and into the coolant channels <NUM>. For example, a portion of the rotor hub <NUM> immediately adjacent to the rotor hub inlet <NUM> can comprise a substantially tapered, angled, and or funnel-shaped configuration so that a combination of centrifugal forces and the configuration can at least partially direct coolant into the coolant channels <NUM> via the rotor hub inlets <NUM>. Additionally, a portion of the rotor hub <NUM> adjacent to the rotor hub inlets <NUM> can comprise structures, such as, but not limited to grooves, slots, guides, etc. that are configured and arranged to direct coolant toward the rotor hub inlets <NUM>. For example, a region of the rotor hub <NUM> can comprise at least one feeder groove (not shown) that can receive coolant and, in combination with the centrifugal force due the movement of the rotor hub <NUM>, direct coolant toward the rotor hub inlets <NUM>.

Different rotor assembly <NUM> cooling configurations can be employed to at least partially optimize magnet <NUM> and rotor assembly <NUM> cooling. By way of example only, coolant can enter the rotor assembly <NUM> via multiple avenues. For example, an electric machine module <NUM> can include the coolant flow path originating with the output shaft coolant channel <NUM> and outlet <NUM> and flowing through the rotor hub channel <NUM> before entering the coolant channel <NUM>. Additionally, the same module <NUM> can also comprise the rotor hub inlets <NUM> and substantially unidirectional coolant channels <NUM> previously mentioned. As a result, a single module <NUM> can comprise coolant flowing through the rotor assembly <NUM> in both directions through coolant channels <NUM> in fluid communication with the rotor hub channel <NUM> and in two different axial directions through coolant channels <NUM> in fluid communication with the rotor hub inlets <NUM> at adjacent to the axial edges of the rotor hub <NUM>.

In addition, the rotor assembly <NUM> can comprise multiple coolant channels <NUM> including the previously mentioned configurations. By way of example only, and in no way limiting the scope of the disclosure, the rotor assembly <NUM> can comprise coolant channels <NUM> in fluid communication with rotor hub channels <NUM> at various points around the circumference of the rotor hub <NUM> (e.g., <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, etc.) and coolant channels <NUM> in fluid communication with rotor hub inlets <NUM> at regular or irregular intervals between the other coolant channels <NUM>. As a result, coolant can flow through multiple coolant channels <NUM> in axial directions to enhance rotor assembly <NUM> cooling, including cooling of the magnets <NUM>.

Claim 1:
An electric machine module (<NUM>) comprising:
a housing (<NUM>) at least partially defining a machine cavity (<NUM>); and
an electric machine positioned substantially within the machine cavity (<NUM>) and at least partially enclosed by the housing (<NUM>), the electric machine including a rotor assembly (<NUM>), including a rotor hub (<NUM>),
the rotor assembly (<NUM>) operatively coupled to an output shaft (<NUM>), the output shaft including at least one output shaft coolant channel (<NUM>) and at least one output shaft coolant outlet (<NUM>) in fluid communication with the output shaft coolant channel (<NUM>),
the rotor assembly (<NUM>) including at least one magnet (<NUM>), a first axial end, and a second axial end, the first axial end opposing the second axial end,
the rotor assembly (<NUM>) including a plurality of coolant channels (<NUM>) extending from the first axial end to the second axial end, the plurality of coolant channels (<NUM>) in fluid communication with the machine cavity (<NUM>),
at least one rotor hub channel (<NUM>) positioned through a portion of the rotor assembly (<NUM>), the at least one rotor hub channel (<NUM>) comprising at least one passageway which extends from at least a portion of the at least one output shaft coolant outlet (<NUM>) to at least a portion of the plurality of coolant channels (<NUM>),
the rotor assembly (<NUM>) including a plurality of rotor laminations (<NUM>), wherein the plurality of coolant channels (<NUM>) is defined between an inner diameter (<NUM>) of the rotor laminations (<NUM>) and an outer diameter (<NUM>) of the rotor hub (<NUM>), wherein the plurality of coolant channels (<NUM>) is at least partially defined by recesses (<NUM>) formed in the inner diameter (<NUM>) of the rotor laminations (<NUM>), and wherein the recesses (<NUM>) are arranged so that the coolant channels (<NUM>) are in fluid communication with the machine cavity (<NUM>).