Contra-rotating propeller propulsion system for ships

Abstract

 Applicable to ships or ships of all kinds, having a main propeller (2) actuated by an internal combustion engine (10), and a second propeller (2') that rotates contrary to the first, having a secondary shaft associated to the secondary propeller (2') and coaxially assembled on the primary shaft, forming a shaft line (4), the secondary shaft being related to the primary shaft through a set of conveniently lubricated conical transmission crown wheels housed within a case (5), which cause the movement transmitted by said internal combustion engine (10) to be transmitted to both shafts and with different directions of rotation. Additionally, an electric engine (6) acts on the aforementioned transmission, which may be inoperative, operate jointly with the internal combustion engine (10) or operate in an isolated manner while said combustion engine is stopped, in order to increase the power of the ship, reduce its speed and/or reduce the acoustic contamination of the ship's power unit.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a propulsion system for boats or ships of all kinds wherein, in addition to a main propeller, a secondary propeller rotates contrary to the main propeller, in order to optimize the propulsion and eliminate cavitations.

[0002] The object of the invention is to ensure, on one hand, that the main engine of the ship can move both contra-rotating propellers simultaneously, which in determined circumstances can be supported by an electric engine and, on the other, that even the propulsion can be carried out exclusively by said electric engine, when for different reasons and as we will see later on, it is necessary or advisable to reduce the ship's acoustic contamination to a maximum.

BACKGROUND OF THE INVENTION

[0003] The benefits of having a second propeller positioned at the stern of the main propeller, on the same plane, as close as possible and rotating contrary thereto, have been known for many years.

[0004] The use of a contra-rotating double propeller is known to offset rotational losses, optimising the propulsion of any kind of ship, increasing its performance, reducing the consumption of fuel and therefore greenhouse gas emissions. Similarly and on increasing the contact surface of water with the propeller, the pressure on its blades is considerably reduced, thereby eliminating cavitations (noise and vibration).

[0005] The methods used to date to achieve the improvement described are based on the additional installation of POD-type azimuthal systems positioned at the stern of the main propeller. Said azimuthal mechanisms are normally actuated by electric engines, due to which the installation of a diesel power generator to supply the necessary electrical energy for its operation is essential. It is a complex and very expensive system that can only be amortised in ships of considerable length, wherein fuel consumption represents a significant part of its operating costs.

[0006] Even in the water sports sector and for the same reasons, the use of propelling tails equipped with contra-rotating double propellers has recently been popularised. For this reason, leading market brands such as Volve Penta, MerCruiser and other manufacturers have launched products with these characteristics on the market.

[0007] For this reason, one of the objectives of this invention is to resolve all the aforementioned disadvantages by providing a mechanism or mechanical device that allows the installation of a conventional in-line contra-rotating double propeller, and which can also be assembled in pre-existing ships without the need for complex mechanical or structural transformations.

DESCRIPTION OF THE INVENTION

[0008] This and other objectives of the invention are achieved by means of a hybrid propulsion system for in-line contra-rotating propellers for ships, according to independent Claim 1. The specific embodiments of the system that is the object of the invention are defined in the dependent claims.

[0009] To this end and more specifically, the main shaft of the ship, which in turn bears the main propeller and is associated to the main engine thereof, normally an internal combustion engine, is divided into two in its terminal sector in a secondary, tubular shaft, coaxially assembled on the main shaft and solidly joined to the corresponding secondary or contra-rotating propeller with respect to the primary, main propeller, both shafts being inter-related through a set of gear wheels, that not only transmits the movement of the main shaft to the secondary shaft but also reverses the direction of rotation to achieve the contra-rotation of the propellers.

[0010] Specifically, the insertion of a bevel gear wheel on the main shaft, at an appropriate distance from its propeller and with the collaboration of conical tightening rings, has been envisaged, the geometrical axis whereof logically coincides with the main shaft of the aforementioned engine and which, through a second bevel gear wheel, the geometrical axis whereof is perpendicular to the former, transmits a rotating movement contrary to that of a third bevel gear wheel, which in turn is conveniently flanged to the secondary shaft, the elements that participate in this transmission being duly assisted by bearings, in addition to a pressure oiling circuit.

[0011] In accordance with a preferred variant of a practical embodiment of the invention, the intermediate bevel gear wheel, that of the geometrical axis perpendicular to the primary and secondary shafts, is associated through a clutch to an electric propulsion engine, that transmits the movement of both shafts, i.e. both the primary and secondary shafts, through the other two bevel gear wheels, in such a manner that said electric engine can be inoperative when deemed convenient, can support the internal combustion engine when necessary, or can act in an isolated manner, i.e. with the internal combustion engine stopped and isolated from the transmission system by means of the corresponding clutch when a very slow movement of the ship is required, such as for example one or two knots, which cannot be obtained with a conventional internal combustion engine and/or when the noise level must be substantially reduced, such as for example during biological inspections of certain marine areas.

[0012] The aforementioned conical tightening rings of the first gear wheel with respect to the primary or secondary shaft, allow the distance between the two propellers to be adjusted.

[0013] The electric engine will also be assisted by a clutch, and said engine shall be controlled by a frequency variator governed from the ship's bridge.

[0014] Finally, it must be pointed out that, not only can the hybrid propulsion system be installed in a new ship, but also easily applied to a pre-existing ship.

DESCRIPTION OF THE DRAWINGS

[0015] For the purpose of complementing this description and to further explain the characteristics of the invention, a set of drawings has been included in accordance with a preferred embodiment thereof as an integral part of this specification, wherein the following figures have been represented in an illustrative and unlimitative manner:

Fig. 1

shows, according to a schematic representation, the power unit of a ship equipped with the hybrid propulsion system for contra-rotating propellers that comprises the object of the present invention;

Fig. 2

shows an enlarged detail, of an elevational side and sectional view, of the part of the assembly of the preceding figure corresponding to the transmission between the primary shaft and secondary shaft, including the electric engine;

Fig. 3

shows a representation similar to that of Figure 2, where the elements corresponding to the pressure oiling circuit have been highlighted; and

Fig. 4

shows, finally and also in a representation similar to that of figures 2 and 3, an example of practical embodiment wherein two electric engines participate.

PREFERRED EMBODIMENT OF THE INVENTION

[0016] Within the foregoing figures, a general diagram of the whole power unit of the ship has been represented in Figure 1, specifically the rudder (1), the main propeller (2) and the contra-propeller (2'), the coil (3) by means of which the shaft line (4) rotates over the hull of the ship, the case (5) that houses the transmission means corresponding to the hybrid propulsion system of the invention in its interior, the secondary engine (6) that participates in said system with its corresponding clutch and reducer (7), and the elastic coupling (8) and reducer (9) corresponding to the main engine (10).

[0017] In an embodiment of the invention, the main engine (10) is of the internal combustion type and the secondary engine (6) is electric.

[0018] The case (5) is crossed by the primary shaft (11) corresponding to the main propeller (2) and stemming from the main engine (10), and the secondary shaft (12), that corresponding to the secondary propeller or contra-propeller (2'), is established coaxially on the primary shaft (11) approximately halfway down said case.

[0019] A first bevel gear wheel (14) is joined by a series of tightening conical rings (13) to the primary shaft (11), conveniently watertighted with respect to the case (5) in the penetration area of the latter, which rotates jointly with said primary shaft (11) and is coaxial thereto. A second bevel gear wheel (15) is engaged with this bevel gear wheel (14), having a perpendicular axis to the primary shaft (11) which, as in the case of the bevel wheel (14), is assembled on the case (5) by means of bearings (16), said second bevel gear wheel (15) being engaged with a third bevel gear wheel (17), also assembled on the ball bearing (16) and conveniently fixed to the secondary shaft (12) by a flange (18).

[0020] This transmission causes the secondary shaft (12) to rotate contrary to that of the primary shaft (11), consequently causing the main propeller (2) to rotate in turn contrary to that of the secondary propeller (2').

[0021] The intermediate bevel gear wheel (15), more specifically the shaft thereof, is conveniently associated through said clutch and reducer (7) to the secondary engine (6), which by means of the transmission of the aforementioned bevel gear wheels (14, 15 and 17), is capable of transmitting movement to both the primary shaft (11) and secondary shaft (12).

[0022] When the availability of space makes it possible, the secondary engine (6) can be substituted for two smaller and opposing secondary engines (6-6'), as shown in Figure 4, in which case the shafts of said engines (6-6') end in respective bevel gear wheels (19-19'), which engage with an intermediate crown wheel (20) opposed and coaxially associated to the bevel gear wheel (15) pertaining to the main, previously described transmission.

[0023] In an embodiment of the invention, the secondary engines (6, 6') are electric.

[0024] In order to achieve optimal operation and a long useful life of the system, it is assisted by an oiling circuit comprised of an oil tank (21) established in the lower part of the case (5), from which a pressure pump, not represented, draws oil, through an intake filter (22) and injects it in a point (23) located on the inlet of the primary shaft (11) in the case (5), and complementarily at the inlets (24) located in the upper part of the case corresponding to the clutch-reducer unit (7) established between the electric engine (6) and the main transmission, the oil returning to the tank (21) by gravity, via a return (25). Additionally, and in compliance with the legislation detailed below, the system has a second intake filter (26), using the first filter (22) for oiling under normal conditions, and the second filter (26) for oiling with an emergency unit.

[0025] Pursuant to the applicable legislation, this oiling circuit shall be double, a circumstance that explains the presence of the two aforementioned intake filters (22, 26).

[0026] It is also worth noting that an external pressure regulating valve is installed at the pressure outlet of said pump which has an inlet and two outlets, in such a manner that said pressure firstly reaches the inlet (23) and, on exceeding a predetermined pressure, an external regulating valve diverts the flow toward the inlets (24).

[0027] For the purpose of cooling the previously described hydraulic circuit, a coolant is inserted, specifically between the filter and the upper oiling inlet. Said coolant can be water-oil, or air-oil, necessarily including, in the latter case, an electric fan.

[0028] The system considerably facilitates the maintenance tasks without the need for skilled labour, only requiring the periodic replacement of the filters (22 and 26) and lubricating oil.

Claims

1. A ship hybrid propulsion system for in-line contra-rotating propellers, shaft lines wherein a main propeller that rotates in a determined direction and a secondary propeller that rotates in the opposite direction are established, characterised in that it comprises

- a primary transmission shaft (11) corresponding to the main propeller (2), actuated by the main engine (10), and

- a secondary tubular shaft (12), corresponding to the secondary propeller (2'), coaxially assembled on the primary shaft (11) of the transmission,

both shafts (11, 12) being inter-related by means of a transmission (14-15-17) which causes said secondary shaft (12) to rotate contrary to the primary shaft (11).

2. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 1, characterised in that the transmission that relates the primary shaft (11) with the secondary shaft (12) comprises

- a first bevel gear wheel (14), coaxially assembled on the primary shaft (11),

- said first bevel gear wheel (14) being engaged with a second bevel gear wheel (15), its axis being perpendicular to the primary shaft (11),

- which is in turn engaged with a third bevel gear wheel (17), its axis being parallel to both the primary shaft (11) and secondary shaft (12),

said bevel gear wheels being assembled with freedom of rotation on the case (5) that contains them.

3. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 1, characterised in that the main engine (10) is an internal combustion engine.

4. Ship hybrid propulsion system for in-line contra-rotating propellers, according to claims 1 and 3, characterised in that the main engine (10) actuates the main shaft (11), and consequently the main propeller (2), through an elastic coupler (8) and a reducer (9).

5. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 2, characterised in that the bevel gear wheel (14) is solidly joined to the primary shaft (11) by means of tightening conical rings (13).

6. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 2, characterised in that the bevel gear wheel (17) is fixed to the secondary shaft (12) by means of a flange (18).

7. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 2, characterised in that the bevel gear wheels (14, 15, 17) are free to rotate on the case (5) by means of bearings (16).

8. Ship hybrid propulsion system for in-line contra-rotating propellers, according to any of the preceding claims, characterised in that, in addition to the main engine (10), the transmission (14, 15, 17) receives the movement of at least one secondary engine (6) susceptible to being inoperative, of acting jointly with the main engine (10) or acting in an isolated manner with said main engine (10) stopped.

9. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 8, characterised in that the secondary engine (6) is electric.

10. Ship hybrid propulsion system for in-line contra-rotating propellers, according to claims 2 and 8, characterised in that the axle of the intermediate bevel gear wheel (15) is associated to the secondary engine (6) shaft.

11. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 10, characterised in that the secondary engine (6) shaft is associated to the intermediate bevel gear wheel (15) by means of a clutch-reducer unit (7).

12. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 8, characterised in that, in the event of lack of space for installing the secondary engine (6), two smaller secondary engines (6-6') participate in the system, with their shafts associated to respective bevel gear wheels (19-19'), inter-related by an intermediate bevel gear wheel (20) associated in turn to the intermediate bevel gear wheel (15) that relates the bevel gear wheels associated to the primary shaft (11) and the secondary shaft (12).

13. Ship hybrid propulsion system for in-line contra-rotating propellers for ships, according to Claim 12, characterised in that the secondary engines (6, 6') are disposed in opposition, and the bevel gear wheels (19, 19') face each other.

14. Ship hybrid propulsion system for in-line contra-rotating propellers, according to Claim 12, characterised in that the secondary engines (6, 6') are electric.

Drawing