[0001] The present invention relates to an electrical power transmission system between
one ore more pairs of conductors, particularly for electricity transmission to a propulsion
and steering module for naval ships of the POD type.
[0002] In commonly used propulsion and steering modules for naval ships, the electrical
power transmission between a power supply housed in the ship hull and a motor housed
inside the pod of the propulsion and steering module, is performed by means of a series
of brushes integral to the ship frame, and therefore always fixed, and a series of
conductive rings mounted on the propulsion and steering module stem, solidly rotating
with it.
[0003] Alternatively, electrical power transmission can also be performed by means of brushes
solidly rotating with the propulsion and steering module stem, and conductive rings
integral to the ship frame, and therefore fixed.
[0004] In both cases, since ships generally navigate at cruising speed for long periods,
the propulsion and steering module stays fixed in relation to the ship hull, and consequently
the position of brushes is fixed in relation to the conductive rings. In this way,
current flows always through the same points from the power supply to the electric
motor. This causes serious problems because the brush-ring surfaces do not perfectly
match and so electrical current can not uniformly distribute but passes through preferred
contact points.
[0005] This causes local temperature increase, consequently causing micro-craters. The contact
resistance grows causing a self-feeding phenomenon. Besides, on the ring parts normally
not in contact with the brushes, can occur superficial coats due to oxidation phenomena
facilitated by the marine environment.
[0006] During operating manoeuvre, the brushes come in contact with these surfaces. This
causes bad conduction and local temperature increase, due to the high contact resistance;
besides, brushes deterioration occurs because of their own foul.
[0007] The main task of the present invention is therefore to realize an electrical power
transmission system between one or more pairs of conductors, which allows to obtain
an optimal conduction, avoiding wear between brushes and contacts.
[0008] As part of this task, one object of the present invention is to provide an electrical
power transmission system between one or more pairs of conductors which allows to
avoid the forming of a coat due to oxidation phenomena facilitated by the marine environment.
[0009] Another object of the present invention is to provide an electrical power transmission
system between one or more pairs of conductors, which can be used in propulsion and
steering module naval ships.
[0010] This task, together with these and other objects that shall emerge more clearly hereinafter
are achieved by an electrical power transmission system between one or more pairs
of conductors characterised by the fact that it comprises a first sliding contact
means connected to a first conductor of said one or more pairs of conductors, a second
sliding contact means, connected to a second conductor of said one or more pairs of
conductors, and a third sliding contact means in continuous relative motion in relation
to said first and second sliding contact means.
[0011] In this way the electric contact between the sliding contact means occurs along mobile
contact surfaces, thus avoiding the cited problems in that all the surface is involved
in current flow. A further advantage is due to the fact that the continuous relative
motion between the sliding means prevent the occurring of the surface coat.
[0012] Further advantages and characteristics of the present invention, will emerge from
the description of a number of preferred but not exclusive embodiments of the electrical
power transmission system according to the invention, illustrated purely by way of
example and without limitation with the aid of the attached drawings in which:
figure 1 shows a naval ship with a propulsion and steering module;
figure 2 shows a longitudinal section of the electrical power transmission system
according to the invention;
figure 3 shows a cross section taken along the plan III-III of figure 2.
[0013] In particular figure 1 shows a naval ship 1 on the hull of which a propulsion and
steering module 2 of the POD type is mounted, comprising a pod 40 and a support 50,
electrically fed by means of the electrical power transmission system 3.
[0014] Figure 2 and 3 show a preferred embodiment of the electrical power transmission system.
In this embodiment, a pair of conductive cables 6 and 14 are connected to, respectively,
a first sliding contact means 7 and a second sliding contact means 25 of the electrical
power transmission system according to the invention.
[0015] In the illustrated embodiment the first sliding contact means 7 are made of brushes
coupled to the ship frame 1 and therefore fixed; the second sliding contact means
25 is made of graphite rings 12 and of conductive rings 11 coupled each other and
to the stem 5 of the propulsion and steering naval ship 2.
[0016] The second sliding contact means are electrically insulated from the stem 5 by insulating
means 13. Between the brushes 7 and the graphite rings 12, a third sliding contact
means 8 are provided, fixed on the support means 10 and electrically insulated by
insulating means 9.
[0017] In the embodiment illustrated, the sliding contact means 8 are made of rotating conductive
rings and the support means 10 are made of a rotating roll holding rings.
[0018] Alternatively, the first sliding contact means 7 can be made of graphite rings, and
the graphite rings 12 can be made of brushes. The rotating roll 10 can be realised
with metallic material or plastic-composite material thus making the insulating means
9 useless.
[0019] Alternatively, the supporting means 10 can be made of a set of rotating stems holding
the rings or the brushes.
[0020] Driving and guiding means 17 directly operate on said rotating roll 10, comprising
in the illustrated embodiment, a motor 16 driving a gear 18-pinion 15 system and a
sliding guide 20. The guide 20 can be made of a circular rail, or anyway of sliding
means facilitating the rotation of the roll 10.
[0021] The electric motor 16 acts on the gear 18-pinion 15 system which operates on the
rotating roll 10, making it rotate inside the guide 20. In this way, being the rotating
rings 8 constrained to said roll 10, they also rotate generating a continuous sliding
contact, both with the brushes 7 and the graphite rings 12, along all the surface
of the rotating ring 8 itself, even when the ship navigates at cruise speed, and the
propulsion and steering module is fixed in relation to the ship hull.
[0022] A particular application of the electrical power transmission system according to
the invention, occurs when a propulsion and steering module for naval ships comprising
a submerged watertight pod, inside which an electric motor is housed, and a substantially
vertical support, the bottom part of which is joined to the pod and the top part of
which is connected to the hull of said naval ship in such a way as to be able to rotate
in relation to the longitudinal axis of the hull and inside which electronic power
and control modules are housed.
[0023] In this case the power supply between the fixed part (hull) and the mobile part (pod
and support) conveniently occurs by means of two direct current conductors only, and,
as a consequence, the electrical power transmission system according to the invention
comprises two rotating conductive rings only. With this solution contacts wear is
not uniformly distributed for both the polarities, but this phenomenon can be easily
compensated employing known techniques.
[0024] When the power and control electronic modules are housed inside the ship hull, the
power supply between the fixed part (hull) and the mobile part (pod and support) occurs
by means of alternate current, and the number of conductors ranges accordingly from
3 to 8, in case of synchronous motor, asynchronous motor, three-phase motor, or hexa
phase motor; as a consequence, the electrical power transmission system also comprises
a number of rotating conductive rings ranging from 3 to 8.
[0025] The electrical power transmission system as conceived is capable of numerous modifications
and variants that are all within the inventive concept; moreover all the details may
be substituted by other technically equivalent elements. In practice the dimensions
and materials used can be of any kind to suit the requirements of the state of technology,
providing they are compatible with the specific use.
1. Electrical power transmission system between one ore more pairs of conductors characterised
by the fact that it comprises:
- a first sliding contact means, connected to a first conductor of one or more pairs
of conductors;
- a second sliding contact means, connected to a second conductor of said one or more
pairs of conductors;
- a third sliding contact means in continuous relative motion in relation to said
first and second sliding contact means.
2. Electrical power transmission system according to claim 1, characterised by the fact
that said third sliding contact means comprise:
- a rotating conductive ring for each pair of conductors;
- electric insulating means for said rotating conductive rings;
- supporting means of said rotating conductive rings;
- operating and guiding means of said supporting means.
3. Electrical power transmission system according to one or more of the previous claims,
characterised by the fact that said supporting means are constituded of a rotating
roll.
4. Electrical power transmission system according to one or more of the previous claims,
characterised by the fact that said supporting means are constituted of a series of
rotating stems.
5. Electrical power transmission system according to one or more of the previous claims,
characterised by the fact that said operating and guiding means comprise a gear-pinion
system.
6. Electrical power transmission system according to one or more of the previous claims,
characterised by the fact that said operating and guiding means comprise a circular
rail for the guide of said supporting means.
7. Electrical power transmission system according to one or more of the previous claims,
characterised by the fact that it comprises:
- brushes connected to the conductors, said conductors being connected to an electrical
power source;
- graphite rings and conductive rings coupled each other and fixed to a rings-holder
stem, said conductive rings being connected to the supply cables of a consumer electric
device and electrically insulated from said stem by insulating means;
- rotating conductive rings interposed between said brushes and said graphite rings,
said rotating conductive rings being in continuous relative motion in relation to
said brushes and to said graphite rings, realising a continuous sliding contact with
both them;
- electrical insulating means for said rotating conductive rings;
- a rotating roll for supporting said rotating conductive rings; and
- an electric motor, a gear-pinion system, and a slipping circular rail, for the handling
and guiding of said rotating roll.
8. Propulsion and steering module for naval ship comprising a submerged watertight pod
containing an electric motor, and a cooling circuit comprising a pump and a heat exchanger;
- a substantially vertical support, the bottom part of which is fixed to said pod
and the top part of which is connected to the hull of said naval ship in such a way
as to be able to rotate in relation to the longitudinal axis of the hull;
characterised by the fact that it comprises an electrical power transmission system
according to one or more of the previous claims.
9. Propulsion and steering module for naval ship according to claim 8, characterised
by the fact that the power and control electronic modules of the electric motor are
housed inside the support and the supply of said electric motor occurs by means of
two direct current conductors.
10. Propulsion and steering module naval ship according to claim 8, characterised by the
fact that the power and control electronic modules of the electric motor are housed
inside the hull of a naval ship, and the power of said motor occurs by means of at
least three alternate current conductors.
11. Propulsion and steering module naval ship comprising:
- a submerged watertight pod, containing a cooling circuit comprising a pump and a
heat exchanger; and a permanent magnet multielectronic rotating motor or a variable
reluctance motor;
- a substantially vertical support, the bottom part of which is fixed to said pod
and the top part of which is connected to the hull of said naval ship in such a way
as to be able to rotate in relation to the longitudinal axis of the hull, said support
comprising power electronic modules and access means to said support characterised
by the fact that it comprises an electrical power transmission system, from a supply
system housed in the hull to said multielectronic motor housed in the pod, according
to claims from 1 to 7.