Patent Application
20200195084
Internal permanent magnet (IPM) motors are synchronous motors with rotating magnetic fields that have magnets embedded in the rotors of the motor. These motors can use both the torque due to the magnet magnetization and the reluctance torque due to the rotor magnetization. Since the magnets are typically embedded in rotors made from robust materials, such as silicon steel plates, the centrifugal force during the motor rotation typically does not dislodge the magnets from their positions, which results in high mechanical stability. Some IPM motors allow for control of the current phase to run with high torque over a wide range of speeds. This makes these motors very energy-efficient, while still allowing for a high torque output. Recently, the use of IPM motors has been expanding rapidly in electric vehicles, hybrid vehicles, and/or other transportation applications.
One of the challenges that arises during the use of IPM motors is that the use at high speeds found in many motor vehicle applications often involves difficulties in cooling the motor consistently and evenly. During normal operation, waste heat may be produced by the IPM motor through the relative motion of the stator and/or rotor. Therefore, most motors are equipped with an appropriate cooling system that circulates coolant in, around, or through channels in the motor. Without optimized cooling, excessive temperatures can affect the efficiency of the motor and lead to dangerous operating conditions. Therefore, improvements are needed in the art for designing cooling channels that are both effective at circulating coolant and easy to manufacture and assemble.
In some embodiments, a housing for cooling an electric motor in an electric vehicle may include a tubular frame that may include a first end and a second end. The first end may include a first plurality of openings. The second end may include a second plurality of openings. The tubular frame may include a first plurality of channels encased in the tubular frame running between the first plurality of openings and the second plurality of openings. The housing may also include a first cover configured to mate with the first end of the tubular frame. The first cover may include a third plurality of openings positioned to mate with the first plurality of openings of the tubular frame, and a second plurality of channels that connect ones of the first plurality of openings to others of the first plurality of openings. The housing may also include a second cover configured to mate with the second end of the tubular frame. The second cover may include a fourth plurality of openings positioned to mate with the second plurality of openings of the tubular frame, and a third plurality of channels that connects ones of the second plurality of openings to others of the second plurality of openings. The first plurality of channels, the second plurality of channels, and the third plurality of channels may form pathways through which coolant can flow.
In some embodiments, an interior permanent magnet (IPM) motor may include a stator having a plurality of conductors, where the stator is disposed concentrically around an axis. The motor may also include a plurality of rotors disposed concentrically around the axis inside of the stator. The motor may also include a housing disposed concentrically around the axis. The housing may include a tubular frame that may include a first end and a second end. The first end may include a first plurality of openings. The second end may include a second plurality of openings. The tubular frame may include a first plurality of channels encased in the tubular frame running between the first plurality of openings and the second plurality of openings. The housing may also include a first cover configured to mate with the first end of the tubular frame. The first cover may include a third plurality of openings positioned to mate with the first plurality of openings of the tubular frame, and a second plurality of channels that connect ones of the first plurality of openings to others of the first plurality of openings. The housing may also include a second cover configured to mate with the second end of the tubular frame. The second cover may include a fourth plurality of openings positioned to mate with the second plurality of openings of the tubular frame, and a third plurality of channels that connects ones of the second plurality of openings to others of the second plurality of openings. The first plurality of channels, the second plurality of channels, and the third plurality of channels may form pathways through which coolant can flow.
In any embodiments, any of the following features may be included in any combination and without limitation. The first plurality of channels may be narrower than the second plurality of channels. The first plurality of channels may include alternating pairs of channels, where coolant may flow in same directions in each of the pairs of channels. Each of the pairs of channels in the tubular frame may include a space between the pairs of channels, where the space may be less than 25% of a width of one of the first plurality of channels. The third plurality of openings in the first cover comprises pairs of openings, wherein each of the pairs of openings receive coolant flowing in same directions. Each of the second plurality of channels in the first cover may connect ones of the pairs of openings in the first cover to others of the pairs of openings in the first cover. Each of the second plurality of channels may include a first section, a second section, and the third section, where the second section may connect the first section to the third section, and where the second section may be narrower than the first section and the third section. The second plurality of channels may extend to cover a portion of the first and of the tubular frame. The second cover may include an inlet valve and an outlet valve. The coolant may flow in through the inlet valve, through the first plurality of channels, the second plurality of channels, and the third plurality of channels, and out through the outlet valve.
A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, wherein like reference numerals are used throughout the several drawings to refer to similar components. In some instances, a sub-label is associated with a reference numeral to denote one of multiple similar components. When reference is made to a reference numeral without specification to an existing sub-label, it is intended to refer to all such multiple similar components.
Described herein, are embodiments for a motor housing with integrated cooling channels that provide a thorough and efficient pathway for liquid coolant to flow around an electric motor. According to some embodiments, the housing may include a plurality of sections, including a hollow tubular frame and first and second covers that can be mated with the tubular frame. Because the tubular frame is hollow, the stator and rotors of the engine can be inserted inside the hollow tubular frame. Encased within the wall of the tubular frame, some embodiments may include a plurality of channels that run parallel to a central axis of the tubular frame. Each of these channels may include an opening at each end of the tubular frame. A front, or first cover may include a plurality of openings that mate with the openings on the tubular frame formed by the frame's channels. The first cover may include another (second) plurality of channels that connects sets of its openings in the tubular frame together. The channels in the first cover may extend in a plane that is perpendicular to the axis of the tubular frame, allowing the channels to cool the motor along the front side and in a direction that is different from the channels in the tubular frame. Additionally, the housing may include a second, or back cover that also includes openings that mate with the channel openings in the tubular frame. The second cover may also include another (third) plurality of channels that connect sets of openings in the tubular frame together in the second cover. When assembled, the first and second covers and the tubular frame connect the various channels embedded within each component together to form a continuous pathway through which liquid coolant can flow in alternating directions up and down the length of the housing, as well as along the front cover of the housing to efficiently and effectively cool the motor. Some portions of this continuous pathway may be narrower than other portions, which may create a pressure differential and help move the coolant through the pathway.
In
The electric vehicle 100 may also include a drive shaft 110 that may include one or more differential units 104, 106, axles, and/or steering mechanisms. The drive shaft 110 may be rotated by virtue of its connection to the rotors of the motor 114. The differential units 104, 106 can translate the axial rotation of the drive shaft 110 into a corresponding rotation of the wheels 102.
The housing may include a plurality of individual sections or components. For example, the housing may include a tubular frame 206. The tubular frame 206 may include a first end and a second and that are open such that the tubular frame 206 forms a tube with a hollow center in which the rotor assembly 204 and stator 208 can reside. The tubular frame 206 may generally be shaped as an open cylinder. It may have a cross-sectional area that forms in approximately circular ring. “Approximately circular” means that minimum and maximum axes of the interior of the cross-sectional area are within 10% of each other. Note that the tubular frame 206 may include irregular protrusions and/or other features that can be used in the assembly and/or mounting process. For example, the tubular frame 206 may include a plurality of ridges 604 that can be used to mount the housing and/or connect the tubular frame 206 to other components of the housing as described in greater detail below. The tubular frame 206 may include a substantially smooth and circular interior that is sized and configured to accept the stator 208 in a secure position.
The housing may also include a front cover referred to herein as a “first cover” 304. The first cover may be configured to mate with the tubular frame 206 such that the first cover 304 substantially covers the front open end of the tubular frame 206. The first cover 304 may include an opening through which the axis of the rotor assembly 204 may protrude. A front bearing cover 302 can be secured to the axle of the rotor assembly 204 to hold the rotor assembly 204 in place relative to the first cover 304. As described in detail below, the first cover 304 may include openings and internal channels through which coolant may be received from corresponding channels in the tubular frame 206.
The housing may also include a rear or “second cover” 306. The second cover may be configured to mate with the tubular frame 206 such that the second cover 306 substantially and/or completely covers the rear end of the tubular frame 206. As with the first cover 304, the second cover 306 may also include openings and internal channels through which coolant may be received from corresponding channels in the tubular frame 206. Additionally, the second cover 306 may include electrical and/or mechanical interfaces to interact with other systems on the electric vehicle 100. For example, the second cover 306 may include an outlet valve 402 and/or an inlet valve 404 through which coolant may flow into its internal channels. The second cover 306 may also be coupled with a rear cover or resolver 308 to cover a central hole in the second cover 306. The second cover 306 may also be coupled with a power box 310 that receives electrical energy from the rechargeable battery 108. Wiring from the power box 310 can pass through a gap left by the rear cover 308 into the stator 208 to power the electric motor.
This section may be configured to be fixed to a portion of the electric vehicle 100. The substantially flat portion may extend along the bottom of the tubular frame 206 and the second cover 306 although not shown explicitly in
In a similar fashion, the second cover 306 can be screwed, bolted, welded, or otherwise attached to the tubular frame 206 by virtue of corresponding mounting holes that are distributed circularly around an outer circumference of the second cover 306. The rear cover 308 can be used to seal the second cover 306 and allow for routing of wires from the power box 310 to the stator 208. The inlet valve 404 and the outlet valve 402 may also be an integrated part of the second cover 306. As described in greater detail below, these valves 402, 404 can be coupled to hoses or tubes that provide liquid coolant to the motor assembly 300. Coolant can flow in through the inlet valve 404, circulate through internal channels inside the second cover 306, pass into internal channels in the tubular frame 206, and travel through internal channels in the first cover 304. The connections of these three members of the housing combine to form a continuous channel through which coolant can flow, eventually exiting through the outlet valve 402.
Each of the first plurality of channels may be completely encased within the tubular frame 206 along the length of the first plurality of channels. However, the first plurality channels may form a first plurality of openings at the open end of the tubular frame 206 that mates with the first cover 304. Similarly, the first plurality channels may form a second plurality of openings at the second open end of the tubular frame 206 that mates with the second cover 306. These openings may have a cross-sectional area that are the same as the cross-section of the first plurality of channels. Turning back briefly to
In some embodiments, the first plurality of channels 502 in the tubular frame 206 may be arranged in alternating pairs of channels. For example,
In some embodiments, the cross-section of the first plurality of channels may be uniform throughout the length of the tubular frame 206. In other embodiments, the cross-section of the first plurality channels may change through the length of the tubular frame 206. For example, the cross-section of the first plurality of channels may gradually decrease in the direction of coolant flow to generate a pressure differential and force coolant through the tubular frame 206. In other embodiments, the cross-section of the first plurality of channels may gradually increase in the direction coolant flow.
The example of
The first cover 304 can be mated with the first open end of the tubular frame 206. A face of the first cover 304 may include a plurality of openings, referred to herein as a “third plurality of openings” that are configured to meet with the first plurality of openings on the corresponding edge of the tubular frame 206. The third plurality of openings on the first cover 304 may be sized to match the first plurality of openings on the tubular frame 206. Thus, when attaching the first cover 304 to the tubular frame 206, coolant can flow through the first plurality of openings into the third plurality of openings without restriction. Alternatively, the third plurality of openings may be substantially larger than the first plurality of openings on the tubular frame 206. This may be particularly true when the third openings expose an entire side of the channels in the first cover 304 as described below.
The third plurality of openings may be connected to additional channels in the first cover 304 referred to herein as a “second plurality of channels.” The second plurality of channels may connect ones of the first plurality of openings to others of the first plurality of openings. For example, sets of one or more openings may be connected to other sets of one or more openings. In the example of
Each of the second plurality of channels may include one or more sections, each of which has differing flow characteristics. For example,
Another feature of the second plurality of channels in the first cover 304 is the direction in which coolant flows around the motor assembly 300. In the tubular frame 206, coolant flows exclusively along an outside diameter of the tubular frame 206. This cools the motor assembly 306 along one surrounding surface. However, some embodiments also allow coolant to flow through the first cover 304 in a direction that is perpendicular to the central axis of the motor assembly 300. This allows coolant flowing through the second plurality of channels in the first cover 304 to also cool the motor assembly 300 along the front of the motor assembly 300. This results in a more uniform cooling of the motor assembly 300, rather than leaving hotter spots at the end(s) of the motor assembly 300. As depicted in
Just as the first cover 304 includes channels and openings that mate with the tubular frame 206 and complete a coolant route between the tubular frame 206 and the first cover 304, the second cover 306 may also do so in a similar fashion. The openings formed by the second cover 306 that mate with the second plurality of openings on the tubular frame 206 may be referred to herein as a “fourth plurality of openings.” Additionally, channels formed inside the second cover 306 may be referred to herein as a “third plurality of channels.” As described above for the first cover 304, the fourth plurality of openings may be configured or position to mate with the second plurality of openings of the tubular frame 206. Each of the third plurality of channels may connect ones of the second plurality of openings to others of the second plurality of openings through the fourth plurality of openings in the second cover 306.
In some embodiments, the third plurality of channels in the second cover 306 may also extend inwards towards a center axis of the motor assembly 300. The third plurality of channels may be arranged having a geometry similar to that of the channels/openings in the first cover 304. Alternatively, as illustrated in
In some embodiments, the third plurality of openings in the first cover 304 need not match the size, shape, or number of the first plurality of openings in the tubular frame 206. Instead, a single opening in the first cover 304 may be configured to accept more than one of the first plurality of openings in the tubular frame 206. The same may be true of the fourth plurality of openings in the second cover 306. In some embodiments, the entirety of the second plurality of channels in the first cover 304 may be open and exposed before the first cover 304 is mated with the tubular frame 206. Thus, the third plurality of openings may share a complete side with the second plurality of channels in the first cover 304. This configuration is visible in
Similarly, the fourth plurality of openings in the second cover 306 may also be completely open on the side adjacent to the tubular frame 206 as visible previously in
In the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of various embodiments of the present disclosure. It will be apparent, however, to one skilled in the art that embodiments of the present disclosure may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form.
The foregoing description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the foregoing description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the disclosure as set forth in the appended claims.
Specific details are given in the foregoing description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may have been shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may have been shown without unnecessary detail in order to avoid obscuring the embodiments.
In the foregoing specification, aspects of the disclosure are described with reference to specific embodiments thereof, but those skilled in the art will recognize that the disclosure is not limited thereto. Various features and aspects of the above-described disclosure may be used individually or jointly. Further, embodiments can be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of the specification. The specification and drawings are, accordingly, to be regarded as illustrative rather than restrictive.
The present application claims priority to U.S. Patent Application No. 62/778,874, filed on Dec. 12, 2018, entitled “MEANDERING COOLANT CHANNELS WITH VARYING WIDTHS IN A MULTI-SECTION MOTOR HOUSING”, which is incorporated by reference herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62778874 | Dec 2018 | US |
