Patent Application
20210242748
This disclosure relates generally to cooling jackets for electrical motors, and particularly to helical cooling jackets with a variable pitch to improve cooling performance and ensure a more uniform spatial distribution of temperature.
The performance and lifespan of permanent magnet (PM) electric motors are sensitive to operating temperatures on or within the copper coil, the magnet, and the shaft. As a result, water, because of its high heat capacity (and thus its effectiveness at carrying away heat when present even in relatively small amounts), is commonly used as a coolant for PM motors. Water cooling is thus the primary method for cooling motors in, by way of non-limiting example, electric vehicles (EVs), because weight, dimension, and efficiency are key to successful powertrain design.
To date, the most common approaches to water cooling of electrical motors employ a cooling “jacket” comprising either inline water channels or helical channels. In helical designs, coolant enters the jacket from one end of the helical channel, loops around the cylindrical face of the electric motor to carry heat away from the motor housing, and exits from the other end of the helical channel at an opposite end of the motor housing. Such designs suffer from at least two drawbacks: first, as the coolant draws heat away from the surface of the motor, the temperature of the coolant increases and the coolant effectiveness concomitantly decreases along the length of the helical channel from the entrance to the exit, and second, the ramp-in and ramp-out sections of the water inlet and outlet are generally characterized by poor coolant flow and thus a “blind spot” in the cooling jacket.
There is, thus, a need in the art for cooling jackets for electric motors that maintain the effectiveness of the coolant along the length of the cooling jacket channels and mitigate or eliminate blind spots in the cooling effectiveness.
Embodiments of the present disclosure include a cooling jacket for an electric motor, comprising a coolant inlet; a coolant outlet; a helical channel, interconnecting and providing a coolant flow path between the coolant inlet and the coolant outlet, and defining and surrounding an annular space adapted to receive the electric motor or a portion thereof; a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel; and a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above cooling jacket include cooling jackets wherein a radial width of the helical channel is substantially constant.
Aspects of the above cooling jacket include cooling jackets wherein the annular space is adapted to receive a stator of the electric motor, wherein an axial length of the cooling jacket is approximately equal to a length of the stator. When the stator is positioned within the annular space, substantially all of an outer surface of the stator may, but need not, be surrounded by the helical channel.
Aspects of the above cooling jacket include cooling jackets wherein the helical channel comprises no more than five turns.
Aspects of the above cooling jacket include cooling jackets wherein the coolant inlet and the coolant outlet are circumferentially offset by between about 0° and about 180°. The coolant inlet and the coolant outlet may, but need not, be circumferentially offset by between about 45° and about 135°.
Aspects of the above cooling jacket include cooling jackets wherein the coolant is water.
Aspects of the above cooling jacket include cooling jackets wherein a cross-sectional area of the helical channel monotonically decreases along the helical channel such that the cross-sectional area is greatest at the coolant inlet and smallest at the coolant outlet.
Embodiments of the present disclosure include a method for cooling an electric motor or a portion thereof, comprising providing a coolant into a helical channel of a cooling jacket via a coolant inlet; passing the coolant through the helical channel; and withdrawing the coolant from the helical channel via a coolant outlet, wherein the cooling jacket comprises a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel, wherein the cooling jacket further comprises a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, and wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above method include methods wherein a radial width of the helical channel is substantially constant.
Aspects of the above method include methods wherein the helical channel defines and surrounds an annular space adapted to receive the electric motor or a portion thereof, wherein a stator is at least partially disposed within the annular space and surrounded by the helical channel, wherein an axial length of the cooling jacket is approximately equal to a length of the stator. Substantially all of an outer surface of the stator may, but need not, be surrounded by the helical channel.
Aspects of the above method include methods wherein the helical channel comprises no more than five turns.
Aspects of the above method include methods wherein the cooling inlet and the cooling outlet are circumferentially offset by between about 0° and about 180°. The cooling inlet and the cooling outlet may, but need not, be circumferentially offset by between about 45° and about 135°.
Aspects of the above method include methods wherein the coolant is water.
Aspects of the above method include methods wherein a cross-sectional area of the helical channel monotonically decreases along the helical channel such that the cross-sectional area is greatest at the coolant inlet and smallest at the coolant outlet.
Embodiments of the present disclosure include an electric motor, comprising a stator; and a cooling jacket extending over at least part of the stator, comprising a coolant inlet; a coolant outlet; a helical channel, interconnecting and providing a coolant flow path between the coolant inlet and the coolant outlet; a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel; and a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above electric motor include electric motors wherein a radial width of the helical channel is substantially constant.
For purposes of further disclosure and to comply with applicable written description and enablement requirements, the following references are incorporated herein by reference in their entireties:
U.S. Pat. No. 7,745,965, entitled “Electrical machine having a cooling jacket,” issued 29 Jun. 2010 to Oestreich (“Oestreich”).
PCT Application Publication 2012/156104, entitled “Cooling jacket for electric motors,” published 22 Nov. 2012 to Schubert et al. (“Schubert”).
PCT Application Publication 2013/041047, entitled “Electrical motor water cooling device,” published 28 Mar. 2013 to Xiao et al. (“Xiao”).
As used herein, unless otherwise specified, the term “pitch” refers to the height of a complete turn of a helix, measured parallel to the axis of the helix.
The present disclosure improves the cooling capacity of a cooling jacket by varying the pitch of a helical channel of the cooling jacket along the axis of the helical channel. More specifically, the pitch of helical channels of cooling jackets of the present disclosure is greatest at or near a coolant inlet of the helical channel and monotonically decreases along the axis of the helical channel until the pitch reaches a minimum at or near a coolant outlet of the helical channel. As a result of this variable pitch of the helical channel, the cross-sectional area of the helical channel monotonically decreases, and therefore the linear and/or rotational flow rate of the coolant through the helical channel monotonically increases, from the coolant inlet to the coolant outlet. The radial dimension of the helical channel may be constant, but may also decrease, or may even increase so long as the increase in the radial dimension is proportionally less than the decrease in the pitch, thereby ensuring that the cross-sectional area of the helical channel monotonically decreases from the coolant inlet to the coolant outlet. Thus, even though the temperature of the coolant (e.g. water) increases as the coolant flows from the coolant inlet toward the coolant outlet, the increase in linear and/or rotational flow rate balances or compensates for the warming of the coolant and provides a more balanced or uniform cooling effectiveness along the entirety of the axis of the helical channel, and therefore about an entire surface of a housing (or part thereof) of an electric motor disposed within the cooling jacket. In other words, the cooling effectiveness of cooling jackets of the present disclosure is substantially uniform, both axially and radially.
The present disclosure still further improves the cooling capacity of a cooling jacket by providing flow-through loops at or near both the coolant inlet and the coolant outlet of a helical channel of the cooling jacket. In the cooling jackets of the prior art, the “ramp-in” and “ramp-out” sections of the helical channel at or near the coolant inlet and the coolant outlet are often characterized by impaired or ineffective flow, which results in cooling “blind spots” and thus “hot spots” on the surface of a housing of an electric motor, i.e. localized areas of ineffective cooling and therefore greater temperature. The flow-through loops of the present disclosure address this issue by allowing for a volume of coolant to circulate about both an inlet end and an outlet end of the cooling jacket multiple times, thus improving the cooling effectiveness of the cooling jacket in these areas and eliminating “blind spots” and/or “hot spots.” The flow-through loops generally take the form of circular loops with a substantially constant position along the axis of the helical channel. More specifically, a first turn of the helical channel is bifurcated into a main channel and a flow-through loop, such that a volume of coolant (e.g. water), upon entering the helical channel via the coolant inlet, may either flow directly along the main channel and thus through succeeding turns of the helical channel along the axis of the helical channel, or circulate through the flow-through loop one or more times before entering the main channel. In this way, at least a portion of the coolant provided to the cooling jacket circulates about an inlet end of the surface of the housing (or part thereof) of the electric motor disposed within the cooling jacket multiple times, thus compensating for any impairment or ineffectiveness of coolant flow and eliminating the “blind spot” or “hot spot.” The same feature is provided, mutatis mutandis, in association with a final turn of the helical channel, such that a volume of coolant may circulate about an outlet end of the housing (or part thereof) multiple times before exiting the cooling jacket.
Referring now to
The change in the pitch of the helical channel 13 provides an additional advantage, namely that the required hydraulic pressure or power of the coolant can be decreased relative to cooling jackets of the prior art. This advantage can be achieved because the pressure drop or loss within the helical channel 13 is minimized as a result of the change in helical pitch.
Referring now to
As illustrated in
Another advantage provided by flow-through loops 14a,b of the cooling jacket 10 of the present disclosure is that it allows the cooling jacket 10 to be constructed in a much greater variety of configurations, specifically with regard to the circumferential positions of the coolant inlet 11 and coolant outlet 12. Helical cooling jackets that have been previously known and described often require that a coolant inlet and coolant outlet be placed at the same, or very nearly the same, circumferential point on the jacket and/or motor housing, and thus that the directions of coolant flow at the inlet and outlet of the cooling jacket be substantially parallel to each other; in many cases, this is an inefficient use of space in the motor compartment and can cause the displacement of other components. The present disclosure, by contrast, allows for many different circumferential positions of the coolant inlet 11 and coolant outlet 12 relative to each other, and so can be adapted to many desired geometries; by way of non-limiting example, the coolant inlet 11 and coolant outlet 12 of the cooling jacket 10 illustrated in
The cooling jacket 10 of the present disclosure provides the foregoing advantages and benefits at a minimum of cost, materials, and complexity. Previous attempts to address the drawbacks of the prior art identified herein have, in many cases, required more complicated constructions of the cooling jacket, particularly the provision of multiple coolant channels running counter-current or cross-current to each other. Although such designs may, in some cases, mitigate or eliminate “blind spots” or “hot spots” on the surface of the motor housing, they generally extend the length of the cooling jacket beyond the length of the stator and/or require very precise positioning of the various coolant inlets and outlets. The simple design of the cooling jacket 10 of the present disclosure eliminates the need for counter-current or cross-current coolant flows; instead, it allows for uniform cooling using just a single coolant flow path, and does so with a minimum of materials and while taking up minimal space in the motor compartment.
In embodiments, when cooling jackets according to the present disclosure, such as cooling jackets as illustrated by
Any of the steps, functions, and operations discussed herein can be performed continuously and automatically.
To avoid unnecessarily obscuring the present disclosure, the preceding description omits a number of known structures and devices. This omission is not to be construed as a limitation of the scope of the claimed disclosure. Specific details are set forth to provide an understanding of the present disclosure. It should, however, be appreciated that the present disclosure may be practiced in a variety of ways beyond the specific detail set forth herein.
A number of variations and modifications of the disclosure can be used. It would be possible to provide for some features of the disclosure without providing others.
Although the present disclosure describes components and functions implemented in the embodiments with reference to particular standards and protocols, the disclosure is not limited to such standards and protocols. Other similar standards and protocols not mentioned herein are in existence and are considered to be included in the present disclosure. Moreover, the standards and protocols mentioned herein and other similar standards and protocols not mentioned herein are periodically superseded by faster or more effective equivalents having essentially the same functions. Such replacement standards and protocols having the same functions are considered equivalents included in the present disclosure.
The present disclosure, in various embodiments, configurations, and aspects, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, subcombinations, and subsets thereof. Those of skill in the art will understand how to make and use the systems and methods disclosed herein after understanding the present disclosure. The present disclosure, in various embodiments, configurations, and aspects, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments, configurations, or aspects hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease, and/or reducing cost of implementation.
The foregoing discussion of the disclosure has been presented for purposes of illustration and description. The foregoing is not intended to limit the disclosure to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the disclosure are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the embodiments, configurations, or aspects of the disclosure may be combined in alternate embodiments, configurations, or aspects other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the disclosure.
Moreover, though the description of the disclosure has included description of one or more embodiments, configurations, or aspects and certain variations and modifications, other variations, combinations, and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights, which include alternative embodiments, configurations, or aspects to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges, or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges, or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.
Embodiments of the present disclosure include a cooling jacket for an electric motor, comprising a coolant inlet; a coolant outlet; a helical channel, interconnecting and providing a coolant flow path between the coolant inlet and the coolant outlet, and defining and surrounding an annular space adapted to receive the electric motor or a portion thereof; a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel; and a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above cooling jacket include cooling jackets wherein a radial width of the helical channel is substantially constant.
Aspects of the above cooling jacket include cooling jackets wherein the annular space is adapted to receive a stator of the electric motor, wherein an axial length of the cooling jacket is approximately equal to a length of the stator. When the stator is positioned within the annular space, substantially all of an outer surface of the stator may, but need not, be surrounded by the helical channel.
Aspects of the above cooling jacket include cooling jackets wherein the helical channel comprises no more than five turns.
Aspects of the above cooling jacket include cooling jackets wherein the coolant inlet and the coolant outlet are circumferentially offset by between about 0° and about 180°. The coolant inlet and the coolant outlet may, but need not, be circumferentially offset by between about 45° and about 135°.
Aspects of the above cooling jacket including cooling jackets wherein the coolant is water.
Aspects of the above cooling jacket include cooling jackets wherein a cross-sectional area of the helical channel monotonically decreases along the helical channel such that the cross-sectional area is greatest at the coolant inlet and smallest at the coolant outlet.
Embodiments of the present disclosure include a method for cooling an electric motor or a portion thereof, comprising providing a coolant into a helical channel of a cooling jacket via a coolant inlet; passing the coolant through the helical channel; and withdrawing the coolant from the helical channel via a coolant outlet, wherein the cooling jacket comprises a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel, wherein the cooling jacket further comprises a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, and wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above method include methods wherein a radial width of the helical channel is substantially constant.
Aspects of the above method include methods wherein the helical channel defines and surrounds an annular space adapted to receive the electric motor or a portion thereof, wherein a stator is at least partially disposed within the annular space and surrounded by the helical channel, wherein an axial length of the cooling jacket is approximately equal to a length of the stator. Substantially all of an outer surface of the stator may, but need not, be surrounded by the helical channel.
Aspects of the above method include methods wherein the helical channel comprises no more than five turns.
Aspects of the above method include methods wherein the cooling inlet and the cooling outlet are circumferentially offset by between about 0° and about 180°. The cooling inlet and the cooling outlet may, but need not, be circumferentially offset by between about 45° and about 135°.
Aspects of the above method include methods wherein the coolant is water.
Aspects of the above method include methods wherein a cross-sectional area of the helical channel monotonically decreases along the helical channel such that the cross-sectional area is greatest at the coolant inlet and smallest at the coolant outlet.
Embodiments of the present disclosure include an electric motor, comprising a stator; and a cooling jacket extending over at least part of the stator, comprising a coolant inlet; a coolant outlet; a helical channel, interconnecting and providing a coolant flow path between the coolant inlet and the coolant outlet; a first flow-through loop, positioned proximate to and in fluid communication with the coolant inlet and a first turn of the helical channel, whereby coolant entering the helical channel via the coolant inlet may flow through the first flow-through loop before flowing into subsequent turns of the helical channel; and a second flow-through loop, positioned proximate to and in fluid communication with the coolant outlet and a final turn of the helical channel, whereby coolant received from preceding turns of the helical channel may flow through the second flow-through loop before exiting the helical channel via the coolant outlet, wherein a pitch of the helical channel monotonically decreases along an axis of the helical channel such that the pitch is greatest at the first turn of the helical channel and smallest at the final turn of the helical channel.
Aspects of the above electric motor include electric motors wherein a radial width of the helical channel is substantially constant.
The phrases “at least one,” “one or more,” “or,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C,” “A, B, and/or C,” and “A, B, or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together.
The term “a” or “an” entity refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more,” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising,” “including,” and “having” can be used interchangeably.
The term “automatic” and variations thereof, as used herein, refers to any process or operation, which is typically continuous or semi-continuous, done without material human input when the process or operation is performed. However, a process or operation can be automatic, even though performance of the process or operation uses material or immaterial human input, if the input is received before performance of the process or operation. Human input is deemed to be material if such input influences how the process or operation will be performed. Human input that consents to the performance of the process or operation is not deemed to be “material.”
