High-power linear electric motor

A high-power linear electric motor comprises an inductor constituted by annular coils surrounding a magnetic core of square or rectangular section, and an armature having an omega section enveloping this inductor on three sides, so as to ensure the passage both of the magnetic flux and of the induced currents. The armature comprises, outside, a magnetic layer extending upon the whole conductive layer, that is to say as well upon the upturned U central part as upon the two side horizontal flanges of the armature.

BACKGROUND OF THE INVENTION 
The present invention relates to a high-power linear electric motor. 
So-called "U-form" linear motors are already known, which comprise (i) an 
inductor constituted by square or rectangular coils wound around a 
likewise square or rectangular core and held by a generally U-sectioned 
support, and (ii) an armature having the form of a U or an omega 
encompassing the prismatic bar constituted by the inductor and its 
support. 
These motors, of which certain are described in U.S. Pat. No. 4,172,229 
have the drawback of the height of the U being large dimensioned. This is 
a particular hindrance when it is desired to adapt these motors to railway 
bogie trucks, to magnetic life or air-cushion systems. In addition, the 
U-support which characterizes them is both difficult to make and to cool. 
SUMMARY OF THE INVENTION 
It is essentially an object of the present invention to remedy these 
drawbacks by a particularly simple design of the armature and of the 
inductor, enabling high yield and good cooling to be obtained. 
To this end, this high-power linear electric motor, comprising an inductor 
constituted by annular coils surrounding a magnetic core of square or 
rectangular section, and an armature having an omega section enveloping 
this inductor on three sides, so as to ensure the passage both of the 
magnetic flux and of the induced currents, is characterized in that the 
armature comprises, outside, a magnetic layer extending upon the whole 
conductive layer, that is to say as well upon the upturned U central part 
as upon the two side horizontal flanges of the armature. 
The motor according to the invention offers the advantages that its 
dimensions in height are reduced by the whole width of the parts bend back 
by 90.degree. and, in addition, the omega-sectioned armature may be 
arranged with its opening downwards, this eliminating any danger of 
blocking by the presence of snow, hail or stones. 
In addition, with such an embodiment, the motor is easier both to make and 
to cool. As it is less awkward to widen the flanges where the longitudinal 
currents circulate, it is possible to obtain a motor furnishing a greater 
thrust for a given weight. 
Particular arrangements for the joins between the sections of armature, the 
lamination of the core, the slabs which constitute the winding and the 
magnetic teeth which separate these slabs, as well as for the support, 
make it possible to obtain a motor of which the technological simplicity 
and cooling capacity are much greater than those of all heretofore known 
motors. 
A casing extending along the support and containing a multiple contact 
switch connected to all the coils enables a multi-speed motor to be 
obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, the linear electric motor according to the 
invention comprises a fixed armature 1 extending along the whole of the 
railway line and having an omega-shaped transverse section. This armature 
1 comprises a central part 2 forming a section in the form of an upturned 
U, this central part being extended, at the ends of its two vertical 
downwardly extending sides, by two horizontal flanges 3 and 4, coplanar 
and symmetrical with respect to the vertical and longitudinal plane of 
symmetry xx' of the motor. The armature 1 is constituted by two adjacent, 
separate parts, namely an inner conducting part 5 and an outer magnetic 
part 6. These two parts are constituted by layers of metals which are 
respectively conducting and magnetic and they are mounted along the 
railway line by successive sections in the longitudinal direction. As 
shown in FIG. 2, each conducting section 5 is fixed to the immediately 
superposed magnetic section 6 solely at its centre, at point 7. This 
allows differences in expansion between the conducting sections 5 and 
magnetic sections 6. 
The passage of the magnetic flux from one magnetic section 6 to a following 
section is improved due to vertical, transverse magnetic plates 8 fixed at 
the ends of the two successive magnetic sections 6. FIG. 2 shows that the 
two transverse plates 8 are advantageously welded to transverse edges 6a 
of the magnetic sections 6, these edges being bent upwardly. The two 
transverse plates 8 are fixed so as to form therbetween a gap just 
sufficient to allow expansions. 
To ensure continuity of the currents in the armature 1 in the longitudinal 
direction, the join between two successive conducting sections 5 is made 
by means of a connecting plate 9 of upturned U section, of which the edges 
of the lower sides are welded to the opposite ends 5a of the two 
conducting sections 5. These ends 5a are advantageously bent upwardly to 
form curved edges to which the connecting plate 9 of upturned U section is 
welded. This plate 9 is housed in the space between the two upwardly 
curved edges 6a of the upper ile inductor 11 of the linear electric motor 
according to the invention comprises a longitudinal core 12 which must 
send magnetic flux in the whole central part 2 of the omega shaped 
armature 1 and which should be laminated in all directions where it sends 
this flux. As this is not possible, the core 12 is laminated horizontally 
in the zones 13 located mainly along the vertical sides of the central 
upturned U-shaped part 2 of the armature 1, and vertically in the zone 14 
located mainly at the end of this hollow central part, i.e. the upper web 
of the upturned U cross section. These laminated parts are subdivided into 
strips which are sufficiently thin to lend themselves, without causing 
excessive losses, to the circulation of a flux slightly oblique with 
respect to the direction of lamination. 
The magnetic core 12 is surrounded by an insulating mandrel 15 about which 
the winding 16 of the inductor 11 is disposed. This inductor winding 16 is 
subdivided into coils, being shown in horizontal and longitudinal section 
in FIG. 3. This Figure shows that the coil comprises, in addition to the 
inner insulating mandrel 15, insulating frontal sides 17 at the two 
longitudinal ends of the coil and an outer insulating envelope 18. 
Each coil of the winding 16 is constituted by flat slabs each formed by 
flat strips 16a and 16b, or groups of flat strips, which are disposed so 
that, from one turn to the other or from one group of turns to the other, 
they are offset alternately on one side and the other. FIG. 3 in fact 
shows that all the strips 16b or groups of strips 16b are offset towards 
the left with respect to the strips or groups of strips 16a disposed 
between the preceding ones. This alternate offset enables cooling channels 
19 of rectangular section, disposed in quincunx to be formed between the 
strips, which offer a much larger cooling surface then the flat annular 
channels usually provided. In this way, a much better cooling is obtained. 
Notched spacers 21 maintain the offset relationship between the strips 16a 
and 16b. These spacers are located in the longitudinal and vertical plane 
of symmetry xx', respectively below and above the central core 13, at the 
location of the lower air intake 22 and the upper air outlet 23. These 
spacers 21 are thus disposed so as not to hinder the flow of cooling air 
through the channels 19 defined between the strips 16a and 16b of the 
winding 16. 
Between the different slabs of turns are placed transverse laminated 
magnetic plates 24 which conduct the magnetic flux. As these plates 24 
must conduct the flux in three directions, they are in the form of an 
upturned U, i.e. the opening of the U is at the bottom, towards the 
opening of the omega-shaped inductor 1. The connections 25 connecting the 
different slabs to one another pass in this opening. 
In their top part, the magnetic plates 24 present a triangular, or, better, 
trapezoidal cut-out as shown in FIG. 1, at the level of the spacers 21 and 
the air outlet 23. In other words, each magnetic plate 24 terminates in an 
edge which is inclined upwardly and outwardly, i.e. moving away from the 
longitudinal plane of symmetry xx'. 
The magnetic plates 24 are placed inside the insulating protecting envelope 
18 of the coil so that the expensive positioning, which consists in 
insulating each slab separately, is avoided. 
Other transverse magnetic plates 26 are placed between the various coils. 
The lower part of these plates 26 is bent so as to form a short fold 27 at 
right angle This short fold 27 is fixed, by means of fixing members 28, to 
a horizontal conducting plate 29 extending in width beneath the whole of 
the armature 1 and projecting slightly with respect thereto as may be seen 
in FIG. 1. This conducting plate 29 replaces the U-support of the U-shaped 
motor and it may take this very simple form by bending the ends of this U, 
leading to the omega shape. The assembly constituted by the magnetic core 
12, the coils constituting the winding 16 and the magnetic plates 24, is 
thus firmly fixed to the lower conducting plate 29 via the transverse 
plates 26. 
The horizontal conducting plate 29 also forms, like the U-support of the 
U-shaped motor, a screen with respect to the leakage fluxes, in that it is 
the seat of induced currents which compensate the parts of the induced and 
inductor currents which cannot be compensated mutually. To this end, it is 
a good electrical conductor. 
The motor according to the invention further comprises a cooling system 
comprising a lateral descending conduit 31 which extends vertically and 
which is disposed to the side of the armature 1. The upper part of this 
descending conduit 31 is connected to a source of cooling air. Its lower 
end is extended by a horizontal casing 32 disposed beneath the lower 
conducting plated 29 in the central part of which is located the air 
intake 22. This cooling air circulates, as indicated by the arrows in FIG. 
1, penetrating through the inductor through the air intake 22 and then 
passing on either side of the central core 12, in the cooling channels 19 
made between the strips 16a, 16b, and this cooling air escapes to the 
outside, passing through the air outlet 23. The lower conducting plate 29 
is also provided with cooling conduits 33 which are pierced horizontally 
in width. These conduits 33 open on the one hand in the two outer vertical 
sides of the lower conducting plate 29 and on the other hand in the casing 
32 through vertical holes made near the air intake 22. The lower 
conducting plate 29 is thus perfectly cooled. 
The various coils of the winding 16 are connected to connections which 
terminate in contact studs 35 of which certain are connected to rotating 
knives 36. These knives 36 together constitute a multiple contact switch 
and they may ensure closure of a plurality of lines of contact (four in 
number in FIG. 1). The fixed studs 37 of these lines of contact are 
connected to studs 35 and to the phases of the electrical supply so that 
as many different couplings are obtained as there are lines of contact. 
Several different synchronism speeds may thus be obtained, for example 80 
and 160 km/hr. (maximum speed 140 km/hr.) for a normal railway motor, 80, 
160, 240 and 320 km/hr. (maximum speed 260 km/hr.) for a very high speed 
train motor. The same motor may be suitable for both applications: it 
suffices to simplify its multiple contact switch for the 140 km/hr. 
version. 
FIG. 5 shows a variant embodiment which reduces the dimensions in width. In 
this case, the magnetic part 6 of the flange 4 of the omega-shaped 
armature 1 is much less wide than the conducting part 5. This conducting 
part is bent around the magnetic part 6 so as to cover its lower and upper 
faces. The sides of the conducting part 5 have a horizontally extending 
U-shaped section, whose width corresponds to the thickness of the flanges 
of the magnetic part 6 taken between the two sides of the U and opening 
towards the longitudinal plane of symmetry xx'. Correlatively, the lower 
plate 29 forming support for the inductor is bent above the flange 4 of 
the armature 1 so as to present a vertical side 29a which is extended by a 
horizontal flange 29b extending towards the plane of symmetry xx'. The 
flange 4 of the armature 1 is thus housed between the lower support plate 
29 proper and the upper flange 29b forming an integral part of the support 
plate 29. The cooling channels 23 made in the plate 29 are naturally 
extended in the vertical side 29 a and in the upper horizontal flange 29b. 
FIG. 6 illustrates the adaptation of a motor according to the invention to 
a railway bogie truck. The opening of the omega shaped armature 1 is 
directed downwardly so that no blocking due to snow, hail or foul play is 
to be feared. The flanges 3, 4 present a slight, outwardly descending 
slope to promote flow of the rainwater and avoid the latter penetrating 
between the magnetic part and the conducting part. 
The parts of the armature 1 are fixed on the railway by means of support 
plates 39 with which are integral the transverse magnetic plates 8 
terminating the sections of the magnetic parts of the armature. These 
support plates 39 are themselves screwed on the ties 41 of the line via 
footings 42. 
The inductor 11 of the motor is borne by its air intake conduit 31 which is 
itself borne by crosspieces 43 connected to longitudinal elements 44 
directly borne by the axle boxes. Consequently, these longitudinal 
elements are not subjected to the displacements connected with the 
existence of the suspension. As to increase in the non-suspended weight, 
this is without drawback due to the extreme lightness of the motors 
designed according to the invention: their total weight is much less than 
that of the fraction of the speed reducer which is fast with the axles on 
the conventional motorised bogie trucks. 
The circulation of cooling air in the inductor of the motor according to 
the invention is ensured by one or more fan 46 and air filter 45 
assemblies mounted at the top end of the air intake conduit 31.