Patent ID: 12191726

In order not to crowd the drawings, some equal elements are not all marked with a number.

FIG.1shows a stator10of an axial-flow electric motor, where there are visible windings12arranged circularly around an axis X and surrounded by a cooling component20, isolated inFIGS.2and3.

The component20consists of an outer circular ring30, an inner circular ring40concentric to the outer ring30, and rectilinear segments or spokes50(in example seven) which join together radially the two rings30,40.

The outer ring30and the inner ring40are centered on the X axis.

Two adjacent segments50and the arcs of ring30,40comprised by them delimit pass-through cavities36of perimeter complementary to three windings12set side by side. The number of segments or spokes50may vary, then varying the number of windings12placed side by side between two adjacent segments50. To minimizing the empty spaces between the pack of windings12and the rings30,40, the latter comprise—respectively on the inner and outer edge—cusps38which occupy the empty space around the rounded profiles of the windings12.

The rings30,40and the segments50are hollow shells and generally form a continuous channel within them to transport a cooling fluid, which enters the component20from an inlet32and exits from a drain34. To lengthen the path of the channel the inlet32and the drain34are e.g. arranged on the ring30in diametrically opposite points.

The circulation of the fluid inside the component20takes place along a path that involves at least once the two rings30,40and at least two segments50. That is, the fluid circulates inside the component20passing from the ring30to the ring40through a segment50and then passing from the ring40to the ring30through a different segment50. During its flowing the fluid licks the windings12and subtracts heat from them.

The number of channels for the cooling fluid inside the component may vary, in particular the number of independent channels. Two or more separate channels can better remove heat from the windings12, guaranteeing a more uniform operating temperature to the motor.

FIG.4shows an example with two channels running through the interior of a component18all around its center.

The component18comprises two parts50,70superimposed and isolated from each other. Each part50,70realizes a circuit for the fluid isolated from the other.

The part50(70) comprises three angular fractions52a,52b,52c(72a,72b,72c) of outer ring and three angular fractions54a,54b,54c(74a,74b,74c) of inner ring, joined together by six equal radial segments56-1,56-2,56-3,56-4,56-5,56-6(76-1,76-2,76-3,76-4,76-5,76-6).

The three angular fractions52a,52b,52c(72a,72b,72c) and the three angular fractions54a,54b,54c(74a,74b,74c) are arcs of circumference subtended by angles of 60 degrees, and are angularly separated from one another by 60 degrees. The six radial segments56-1,56-2,56-3,56-4,56-5,56-6(76-1,76-2,76-3,76-4,76-5,76-6) are arranged along the diagonals of an imaginary hexagon with center on the X axis.

The three angular fractions52a,52b,52c(72a,72b,72c), the three angular fractions54a,54b,54c(74a,74b,74c) and the six radial segments56-1,56-2,56-3,56-4,56-5,56-6(76-1,76-2,76-3,76-4,76-5,76-6) are internally hollow and their juxtaposition creates an overall channel for the cooling fluid.

The channel in component50(70) starts from an inlet58(78), runs through all the hollow elements of the component50(70), and ends with a drain60(80), placed next to the inlet58(78) on the fraction52c(72c).

The inlets58(78) and the outlets60(80) may also be arranged in a radial direction on the outer surface of the outer ring30.

Thus, in the component50(70) the fluid enters the inlet58(78) and runs in sequence: half of fraction52c(72a), the segment56-5(76-1), the fraction54c(74a), the segment56-6(76-2), the fraction52a(72b), the segment56-1(76-3), the fraction54a(74b), the segment56-2(76-4), the fraction52b(72c), the segment56-3(76-5), the fraction54b(74c), the segment56-4(76-6), half of fraction52c(72a), and finally comes out from the drain60(80). The arrows indicate the direction of flow of the fluid.

By way of example, in the component50the fluid may flow in a clockwise direction around the X axis, and in the component70in a clockwise direction around the X axis. However, the flow directions of the fluid in the components50,70can be varied to improve thermal transfer, e.g. with countercurrent flows.

The components50,70can interpenetrate one another, because where one has a void the other has a solid portion. 3D printing allows them to have a structure otherwise impossible to mechanically couple. That's why the radial segments56-1,56-2,56-3,56-4,56-5,56-6(76-1,76-2,76-3,76-4,76-5,76-6) connect the end of the angular fractions52a,52b,52c,54a,54b,54c(74a,74b,74c,72a,72b,72c) with an alternating pattern, that is, the radial segments56-1,56-2,56-3,56-4,56-5,56-6(76-1,76-2,76-3,76-4,76-5,76-6) are attached to each angular fraction52a,52b,52c,54a,54b,54c(74a,74b,74c,72a,72b,72c) in correspondence of opposite angles and relative to the diagonals of that angular fraction52a,52b,52c,54a,54b,54c(74a,74b,74c,72a,72b,72c).

FIG.5shows another cooling component100of an electric motor (windings around the X axis not shown).

The component100consists of an outer circular ring102, an inner circular ring104concentric to the outer ring102, and by rectilinear segments or spokes108which join radially the two rings102,104, which are centered on the X axis.

The adjacent segments or spokes108and the arches of ring102,104comprising them delimit pass-through cavities106of perimeter complementary to a single winding. The number of segments or spokes108can vary, then varying the number of windings that are on the component100.

The rings102,104and the segments or spokes108are hollow shells and altogether form inside a continuous channel to transport a cooling fluid, which enters the component100from an inlet132and exits from a drain134, placed on the ring102at the same point.

The circulation of the fluid inside the component100takes place along a path that starts from the inlet132, runs circularly over the whole ring102to reach all the spokes108, reaches the ring104, runs circularly over the whole ring104to reach all the spokes108and then returns to the ring102through all the spokes108. That is, the fluid circulates inside the component100by passing from the ring102to the ring104through all the spokes108and then by passing from the ring104to the ring102through all the same spokes108. During the flow the fluid licks all the windings and removes heat from them.

FIG.5indicates with160a circular channel inside the ring102through which the fluid can reach all the spokes108. A circular channel inside the ring104, through which the return fluid can reach all the spokes108, is also indicated with150

Unlike the variant ofFIG.4, each winding is now individually cooled on each side thereof. This construction, which sees an increase in the number of spokes108, is possible by reducing the impact of eddy currents circulating in the casing of the component100around the windings, i.e. by building the component100out of electrically insulating material, e.g. in plastic or technopolymer.

In the zoom ofFIG.5a preferred internal structure for the spokes108is shown. A or each spoke108internally comprises radial channels110, parallel to each other, which pass through it radially to connect the channels150,160. The advantage is thus that the whole surface of the spoke108is capable of removing heat.

The zoom ofFIG.5also illustrates a preferred internal structure for the channel160. Since the cooling fluid could flow difficultly in the spokes which are more distant from the inlet132, it is advantageous to compensate the load losses by distributing in a different way the flow of the fluid among the spokes108. To this aim, in the channel160there is a dividing septum140which divides the channel160into two channels:

a flow channel164and a return channel162for the fluid.

The septum140, for each spoke108, separates and isolates some inlets of the channels110from the remaining inlets. Thus the septum140establishes, for each spoke108, how many and which inlets of the channels110form part of the channel162or of the channel164, in effect thereby establishing how many and which channels110in use will bring fluid to the ring104and how many and which channels110in use will return fluid from the ring104to the ring102.

The septum140is configured so that

there are more channels110carrying fluid to the ring104for the spokes108that are more distant from the point132, and instead

there are fewer channels110carrying fluid to the ring104for the spokes108which are closer to the point132.

Thus the load loss is corrected and the fluid flow is uniform in each section inside the rings102,104.

Preferably the component100is constructed as a single piece.

The component100may be fed from the inner ring104by inverting the structure of the rings102,104.

FIGS.6and7show a preferred form of construction200for an inner ring such as the ring104.

The inner ring200comprises on the outer side surface two equal circular series of grooves202which run parallel to the ring200. The recesses202are arranged so that in front of each outlet from the spokes108of a channel110there is on the ring200a recess202.

A recess202of a series is joined by a channel204with the nearest recess202of the adjacent circular series. The channel204extends parallel to the axis X.

The recesses200serve to decrease the dynamic resistance for the outgoing and incoming circulating fluid from/to the channels110.

The channels204put two adjacent recesses202in communication, transferring from one to the other the cooling fluid that exits a channel110and re-enters the adjacent channel110.

To improve the distribution of the fluid in all the channels110, the section of the channel204(seeFIG.7) has a dimension that depends on the angular position with respect to the X axis. In particular, the cross-section of a channel204is greater as one moves away from the entrance of the fluid into the stator and as one approaches the fluid's exit from the stator.

FIGS.8and9show another preferred form of construction for a stator300. Here the outer ring302, the inner ring304and the spokes306are separate pieces, then assembled together. Or two among the outer ring302, the inner ring304and the spokes306are integral pieces, then assembled to the third piece.

In any case, the problem arises of mounting the separated pieces together in a watertight and resistant manner.

A first solution is to apply O-rings along the peripheral circumference of the inner ring304and/or the outer ring302to seal the cooling fluid inside them.

A second solution is to provide the inner ring304and/or the outer ring302with peripheral circular grooves308. A sealant can then be poured into the circular grooves308. The sealant can be e.g. a resin or a solidifying fluid, or a polymeric foam or an adhesive. E.g. the sealant can be polyurethane.

In particular, the solution is practically more effective if after the grooves circular308are filled with the sealant two circular lids, which at the same time adhere to the sealant deposited on the two rings302,304, are applied on the opposite sides of the stator300

The lid may also be used e.g. to stop-up open channels of the spokes.

Circular grooves like the grooves308may be made also on the spokes, to pour the sealant therein and increase the sealing effect.

Circular grooves like the grooves308may be made on one or both sides of the stator.