Patent Description:
Many solutions for cooling a stator of a rotary electric motor already exist.

<CIT>, for example, discloses a cylindrical frame for enclosing and cooling an iron core of a rotary electrical motor. The cylindrical frame comprises two bundles of cooling ducts arranged on an outer lateral surface of the cylindrical frame. One of the bundles of cooling ducts guides cooling fluid from a coolant intake around circumference of the cylindrical frame. Coolant ducts, a reversal region and an outlet region are sealed by a cylindrical jacket that rests against an outer lateral surface of the frame. The jacket includes a slot arranged between the bundles of cooling ducts and between an intake region and the outlet region and is welded to the frame along the slot.

<FIG> of <CIT>, which is a <NUM>(<NUM>) EPC prior art document, show portions of a cylindrical frame for cooling an iron core of a stator of a rotary electric motor. Grooves are provided on an outer surface of a cylindrical frame to form fluid cooling channels A with a cylindrical jacket B press-fitted around the cylindrical frame. The jacket B must however be thick enough to be sufficiently resistant to avoid any bulging of the jacket due to the high pressure prevailing in the fluid cooling channels when the rotary electric motor is operating.

The thickness of the jacket has however a negative impact on the overall footprint of the rotary electric motor.

<CIT> discloses a cooling jacket for an electric motor or driven machine with an inner shell and an outer shell, which enclose between them an annular gap. A plurality of flow guide elements are arranged over the circumference of the annular gap to form a plurality of annular chambers through which a coolant may flow.

<CIT> discloses a housing for an electric motor and/or a generator, having an inner and an outer jacket. The inner jacket is made of metal and the outer jacket is made of plastic. Integrated sealing elements are arranged on around the circumference of the inner jacket to form therebetween channels along which a coolant may flow.

An aim of the present invention is to provide a stator cooling housing with an improved ratio between its overall magnetic performance and its footprint.

Another aim of the present invention is to provide a stator cooling housing that is easy to manufacture and therefore cost-effective.

These aims are achieved by a stator cooling housing for a stator of a rotary electric motor. The stator cooling housing comprises a cylindrical frame adapted to be mounted around an iron core and a cylindrical jacket. The cylindrical frame comprises inlet and outlet channels and an outer lateral surface against and around which the cylindrical jacket is mounted, for example by a press-fit operation. The cylindrical jacket comprises an inner side provided with a plurality of cylindrical grooves forming, with the outer lateral surface of the cylindrical frame, adjacent fluid cooling channels arranged around the cylindrical frame from a frame upper portion to a frame lower portion, with respect to the height of the cylindrical frame. The stator cooling housing further comprises fluid communication portions arranged such that a cooling fluid may run from the inlet channel, through the fluid cooling channels, from the frame upper portion to the frame lower portion, and through the outlet channel to form a cooling circuit, wherein said fluid communication portions comprise flat surfaces machined on the outer lateral surface of the cylindrical frame, said flat surfaces being disposed opposite to the inner side of the cylindrical jacket.

In an embodiment, the fluid communication portions are arranged such that the cooling fluid may run from an upper to a lower cooling channel of any adjacent cooling channels.

In an embodiment, the stator cooling housing comprises a first and a second set of fluid communication portions arranged to bring adjacent cooling channels in fluid communications. The respective median height of each fluid communication portion of the first set is offset with respect to the respective median height of the corresponding fluid communication portion of the second set.

In an embodiment, the offset corresponds substantially to the height of one cooling channel plus the height of one jacket cylindrical resting surface.

In an embodiment, the first and second sets of fluid communication portions are aligned one under the other along the height of the cylindrical frame respectively at a first and at a second angle position.

In an embodiment, the first and second sets of fluid communication portions are diametrically opposed.

According to the invention, each fluid communication portion of the first and second sets comprises a flat surface machined on the outer lateral surface of the cylindrical frame, said flat surface being disposed opposite to the inner side of the cylindrical jacket.

In an embodiment, the cylindrical jacket comprises cylindrical extensions forming therebetween the plurality of grooves. The outer lateral surface of the cylindrical frame comprises jacket cylindrical resting surfaces against which rest respective cylindrical extensions of the cylindrical jacket.

In an embodiment, the total thickness of the jacket comprises a functionalized portion having the plurality of grooves, and a non-functionalized portion having a thickness which is less than half of the total thickness of the jacket.

In an embodiment, several sets of adjacent fins are arranged between the jacket cylindrical resting surfaces so that each set of adjacent fins is positioned inside respective fluid cooling channels.

In an embodiment, upper and lower sealing rings are mounted on an upper, respectively a lower portion of the stator cooling housing. One of the first and second sealing rings is mounted inside a cylindrical groove located on the outer surface of the cylindrical frame while the other of the first and second sealing rings is mounted inside a cylindrical groove of the cylindrical jacket.

Another aspect of the invention relates to a stator for a rotary electric motor comprising the stator cooling housing as described above.

A further aspect of the invention relates to a rotary electric motor comprising the above stator.

In yet a further aspect of the invention relates to a method of manufacturing a stator cooling housing. The method comprises:.

wherein said flat surfaces form fluid communication portions between fluid cooling channels, the flat surfaces being disposed opposite to the inner side of the cylindrical jacket.

In an embodiment, before the step of mounting the cylindrical jacket, a first sealing ring is mounted inside an upper groove of the cylindrical jacket and a second sealing ring is mounted inside a cylindrical groove located on a lower portion of the outer surface of the cylindrical frame.

The invention will be better understood with the aid of the description of several embodiments given by way of examples and illustrated by the figures, in which:.

<FIG> shows a cylindrical frame <NUM> according to an embodiment of the invention. The cylindrical frame <NUM> is in metal, preferably in steel, and is adapted to be mounted around an iron core of a stator. The cylindrical frame <NUM> comprises an outer lateral surface <NUM> which has been machined by means of a lathe to form a plurality of sets of adjacent cylindrical fins <NUM> disposed between corresponding jacket cylindrical resting surfaces <NUM>. A cylindrical jacket <NUM> is mounted around the frame outer lateral surface, for example by a press-fit operation, to obtain the stator cooling housing <NUM>. In this embodiment, there are eight sets of adjacent cylindrical fins <NUM> separated by seven jacket cylindrical resting surfaces <NUM> although the number of sets of adjacent fins and resting surfaces may vary according to other embodiments.

Referring to <FIG> and <FIG>, a first and a second set of flat surfaces 30a, 30b have been milled on the outer surface <NUM> of the cylindrical frame <NUM> such that flat surfaces 30a, 30b of each set are aligned one under the other along the height of the cylindrical frame <NUM>. The first set of flat surfaces 30a is preferably arranged in a diametrically opposed fashion on the frame lateral outer surface <NUM> with respect to the second set of flat surfaces 30b.

A blank of a cylindrical jacket is machined by means of a lathe to form adjacent cylindrical grooves <NUM> on its inner side, as shown in <FIG>, to obtain the cylindrical jacket <NUM>. This cylindrical jacket <NUM> is mounted around and against the frame outer lateral surface <NUM> to form fluid cooling channels <NUM> as illustrated in <FIG> and <FIG> in fluid communication by respective fluid communication portions <NUM> to form a cooling circuit. To this effect, the respective median height of each flat surfaces 30a of the first set is offset with respect to the respective median height of each flat surface 30b of the second set to bring in fluid communication adjacent fluid cooling channels <NUM> through corresponding fluid communication portion <NUM> such that a cooling fluid may run from the uppermost to the lowermost cooling channel as described in detail subsequently. The offset corresponds for example to the height of a cooling channel <NUM> plus the width of an adjacent jacket cylindrical resting surface <NUM>.

Referring particularly to <FIG>, the inner side of the cylindrical jacket <NUM> comprises cylindrical extensions <NUM> mounted against corresponding cylindrical resting surfaces <NUM> of the cylindrical frame <NUM> such that each set of adjacent cylindrical fins <NUM> are positioned inside a corresponding fluid cooling channel <NUM> to increase thermal exchange with the cooling fluid for an efficient reduction of the heat generated by the stator coils.

As shown in <FIG>, the cylindrical frame <NUM> comprises an inlet channel <NUM> extending from an upper cylindrical surface <NUM> (<FIG>) of the frame <NUM>, through a frame upper portion 12a and leading into an inlet recess 22a located between an uppermost set of adjacent fins <NUM> extending from both sides of the inlet recess 22a through approximately between <NUM>° to <NUM>° to respective opposite sides of the uppermost flat surface 30b which is diametrically opposed to the inlet recess 22a as it can be seen in <FIG>.

Referring to <FIG>, the cylindrical frame <NUM> comprises an outlet channel 16b extending from the upper cylindrical surface <NUM> of the frame <NUM>, through most of the height of the frame <NUM> and leading into an outlet recess 22b located between a lowermost set of adjacent fins <NUM> extending from both sides of the outlet recess 22b through approximately between <NUM>° to <NUM>° to respective opposite sides of the lowermost flat surface 30b (<FIG>) which is preferably diametrically opposed to the outlet recess 22b.

Under cooling operation, a cooling fluid runs through the inlet channel 16a, into the first inlet recess 22a, whereupon the cooling fluid separates to run through the uppermost cooling channel <NUM> in clockwise and counterclockwise directions spanning approximately <NUM>°. The cooling fluid then runs through a fluid communication portion 50b of the second set of fluid communication portions 50a, 50b, into a lower cooling channel <NUM> in clockwise and counterclockwise directions spanning approximately <NUM>° until it reaches another fluid communication portion 50a of the first set of fluid communication portions 50a, 50b. The cooling fluid then runs into a lower cooling channel <NUM> and so on until it reaches the outlet recess 22b, whereupon the cooling fluid is sucked in an upward direction along the outlet channel 16b. The cooling fluid therefore runs along clockwise and counterclockwise circular paths around the outer lateral surface <NUM> of the cylindrical frame <NUM>.

With reference to <FIG>, the total thickness d1 of the cylindrical jacket comprises a functionalized portion of a first thickness d2 and a non-functionalized portion of a second thickness d3 forming together the total thickness of the jacket d1. The functionalized portion comprises the adjacent grooves <NUM> forming the fluid cooling channels <NUM> with the corresponding sets of adjacent cylindrical fins <NUM>, and the cylindrical extensions <NUM> which bring rigidity of the cylindrical jacket <NUM> which permits the non-functionalized portion to withstand the pressure exerted outwardly by the cooling fluid, thereby avoiding any bulging on the jacket.

Integrating the adjacent grooves <NUM> in the inner side of the cylindrical jacket <NUM> rather than on the frame outer lateral surface <NUM>, as shown in <FIG>, allows to reduce the thickness of the non-functionalized portion, thereby reducing the external diameter of the stator cooling housing <NUM> in comparison with a stator cooling housing using the cooling arrangement of <FIG>.

The jacket <NUM> is heated and press-fitted and sealed around the cylindrical frame <NUM>. To that effect, an upper sealing ring 60a is fitted inside an uppermost sealing groove <NUM> of the cylindrical jacket <NUM> and presses against the frame upper portion 12a. The frame lower portion 12a comprises a cylindrical groove <NUM> inside which is fitted a lower sealing ring 60b which presses against a lower portion of the cylindrical jacket. The upper and lower sealing rings may be for example O-rings.

The upper sealing ring 60a is arranged on the uppermost sealing groove <NUM> of the jacket rather than around the frame upper portion 12a because of the lack of space in the frame upper portion 12a to accommodate a cylindrical groove due to the presence of the inlet and outlet channels 16a, 16b. The lower sealing ring 60b is arranged on the frame lower portion 12b rather than inside the lowermost groove of the cylindrical jacket to protect the lower sealing ring 60b during the press-fit operation. More particularly, the lower sealing arrangement advantageously avoids the sealing ring 60b to rub against the outer surface <NUM> of the frame <NUM> when the lower edge of the cylindrical jacket <NUM> is brought from the frame upper portion 12a to the frame lower portion 12b during the press-fit operation.

Claim 1:
Stator cooling housing (<NUM>) for a stator of a rotary electric motor, comprising:
a cylindrical frame (<NUM>) adapted to be mounted around an iron core and having an outer lateral surface (<NUM>),
a cylindrical jacket (<NUM>) arranged against the outer lateral surface (<NUM>) of the cylindrical frame (<NUM>), wherein the cylindrical jacket (<NUM>) comprises an inner side provided with a plurality of cylindrical grooves (<NUM>) forming with the outer lateral surface (<NUM>) of the cylindrical frame (<NUM>) adjacent fluid cooling channels (<NUM>) arranged around the cylindrical frame (<NUM>) from a frame upper portion (12a) to a frame lower portion (12b) with respect to height of the cylindrical frame (<NUM>),
wherein the stator cooling housing (<NUM>) comprises fluid communication portions (50a, 50b) arranged such that a cooling fluid may run from an inlet channel (16a), through the fluid cooling channels (<NUM>), from the frame upper portion (12a) to the frame lower portion (12b), and through an outlet channel (16b) to form a cooling circuit
characterized in that the cylindrical frame (<NUM>) comprises the inlet and outlet channels (16a, 16b) and in that said fluid communication portions (50a, 50b) comprise flat surfaces (30a, 30b) machined on the outer lateral surface (<NUM>) of the cylindrical frame (<NUM>), said flat surfaces (30a, 30b) being disposed opposite to the inner side of the cylindrical jacket (<NUM>).