FR2732293A1 - Boat propulsive system used in sea going vessels - Google Patents

Abstract

The system comprises several propellers (1) distributed along the boat longitudinal axis inside a hydraulic tunnel (4). The first propeller is located at the front of the boat, set back from the bow wave formed by the prow, and the following ones are located behind in line. The last propeller is located near the stern of the boat. Device are provided for generating a first air cushion (5) above the water level in the hydraulic tunnel. A second air cushion is generated above the water flotation level, under the part of the hull (7) located either side the hydraulic tunnel. The propulsive system is combined with hydrofoils (6). The first propeller creates a flow of water at a speed greater than that of the boat and causes the boat to move forwards supported on the pressure created behind it. The second propeller repeats the same process, induction, pressurising and supporting the hydrofoil. The third propeller contributes a propulsive power to the boat whose efficiency is greater than the classical rear propeller.

Description

Improved propulsion system for boats
The present invention relates to an improved propulsion system for boats, useful for river or maritime navigation. It further relates to a boat provided with such an improved propulsion system. The invention relates more particularly to a barge, in particular a container barge, provided with such a propulsion system.

 Here we mean by 11 boats "all types of floating craft and by" river navigation "navigation either on rivers, canals or lakes.

 We know the many applications, in the field of maritime navigation, of what is commonly known as the "surface effect". In various forms, more or less sophisticated techniques have made it possible for maritime transport to make considerable progress with regard to the speed and operation of ships.

 The applications generally related to ocean-going vessels, of small or medium tonnage, and concerned the rapid transport of passengers and vehicles.

 The transport of various goods which increasingly accompanies the development of modern economies was mainly done thanks to trucks, whose traffic is growing intensely. The spectacular increase in this traffic has resulted in considerable investment and real nuisance.

 Finally, it is clear that the operation of the navigable networks is, particularly in France, largely in deficit, and that the modernization of this network would absorb a considerable mass of capital, the immediate profitability of which is poorly assured.

 The various solutions currently proposed could not satisfy these various objectives.

 Thus, with the aim of improving the speed of ocean-going vessels under suitable technical and economic conditions, solutions using advanced technology have been devised; these are based on the principle of reducing the friction resistance of the ship, obtained essentially with planing and semi-planing hulls, in particular with hydrofoils and hovercraft. The solutions adopted cannot be applied to the waters of rivers and lakes.

 For river navigation, the approach to the problem is necessarily different. In fact, a moderate increase in the speed of fluvial floating devices can only be sought within the limits imposed by the dimensions of rivers, canals, rivers and lakes.

One of the first limits is the risk of destruction of the banks and the banks by the wake caused by the waves that any object moves in the water. In addition to the difficulties inherent in this navigation are the maneuverability and safety problems.

 It has been proposed in the past to partially solve these problems by providing boats with means of production of an air layer under pressure under the hull, to perform a partial planing on air cushion, and means of propulsion. and submerged orientation, composed of at least three independent motor-propeller groups, mounted on support legs and fixed substantially vertically to the floating boat (see documents FR-A-890086, FR-A-9006748 and EP -A-0466991).

 However, there was still a need to have a fleet, mainly a river, specializing in particular in the transport of standard containers, but whose technical performance would make it possible to ensure, under competitive economic conditions, the transport of varied goods, practically on the whole European river network now open.

 We have now unexpectedly found that it is possible to further improve the navigability of floating devices, both fluvial and maritime, by providing them with an original propulsion system, which will be described later. It also appeared advantageous to combine this propulsion system with means ensuring the partial planing of the boat, this partial planing being as described in the documents mentioned above.

 The first object of the invention is an improved propulsion system for boats, comprising at least three propulsive elements arranged in line in the longitudinal axis of the boat, inside a hydraulic channel or tunnel, and combined with: - means for generating a first air cushion above the level of the water in said hydraulic channel and - means for generating a second air cushion above the level of the flotation water, under the part of the hull of the boat situated on either side of said hydraulic channel.

 The invention further relates to a boat comprising a propulsion system as above, in which are combined with the propulsive bodies hydrofoils disposed aft thereof, suitably under the hull of the boat and in a position corresponding to the air-water interface when the boat is moving. The boat thus equipped advantageously comprises side skirts, or preferably side hulls for a trimaran or catamaran type boat, and also a flexible yoke at the front and an orientable and almost waterproof panel at the stern.

 For convenience, the invention is described below most often with reference to a barge, in particular a container barge, but it also applies, subject to modifications necessary within the reach of ordinary skill in the art, to other types of boats for inland or sea transport of goods, freight or passengers.

The invention will be better understood, with reference to the description below, to the advantageous embodiments also described below and to the accompanying drawings, in which:
Fig. 1 represents a partial schematic cross-sectional view along a vertical plane of a barge-type boat comprising a propulsion system according to the invention,
Fig. 2 shows a top view of a boat according to FIG. 1 having a catamaran type hull and a modular structure;
Fig. 3 represents a partial schematic cross-sectional view along AA of the boat of FIG. 2.

 The propulsion system according to the invention, thus described according to its currently preferred variant, comprises a plurality of propulsive members 1 preferably of the naval propeller type, driven by an appropriate engine 2 and distributed along the longitudinal axis of the boat. The first of these propellers is advantageously located at the front of the boat, set back from the funnel formed by the bow or double bow, that is to say where the water will rush in and is thus sucked in. the propeller, or the flexible front yoke (not shown) for partitioning the air cushion under the shell. The following propellers 1 are arranged aft, at a certain distance from the first. The latter is located towards or preferably near the stern of the boat. These propellers are placed near the end of support legs 3, preferably substantially vertical, fixed at appropriate points in the structure of the hull.

The power units driving these propellers can be functionally interconnected or preferably independent. In the case of electric motors, these can be supplied with alternating or direct current, at medium voltage, by a Diesel group of suitable power. A storage battery of suitable power can be used as a backup for short trips and to deal with possible short-term breakdowns of the Diesel group. If you choose submerged motors coupled to propellers as described in the document
EP-A-0466991, these must be AC motors, to avoid the presence of brushes. However, we prefer motors running on direct current stowed in or housed in the hull, in practice placed in a central girder beam, in the air, above the submerged propellers. angle between each motor and the propeller it drives ensures almost complete transmission of the driving power, with a double reduction (for example ratio 1/3) at the motor level, then directly on the shaft propeller with a bevel gear, which reduces the overall volume to a minimum.

 A motor supplied with alternating current requires a frequency converter, necessarily expensive, for adjusting the speed of the propeller, while a motor supplied with direct current allows this adjustment to be carried out at a lower cost.

 According to a preferred concrete embodiment of the propulsion system according to the invention, it mainly comprises a standard diesel engine (for example an engine for trucks from 160 to 300 hp) coupled to a generator rotating at a high speed of about 3000 rpm. The generator then supplies direct current to a buffer battery, also serving as safety, and / or directly to the propeller motors placed in the dry passageway. The accumulated current also supplies electric or hydraulic cylinders which control the rudder (s) and the anchors, as well as the accessories, such as radars, searchlights and others.

 In order to be able to operate at full capacity, the propulsion system according to the invention further comprises a hydraulic channel or tunnel 4 (see FIG. 3) defined by a longitudinal liner 4 ′, 4 ″, 4 ″ ″ substantially in an U inverted by appropriate width so that it can laterally surround the propellers 1 and surmounting them so that a volume of air 5 remains above them, when they are in their submerged position. This volume of air is put under overpressure by appropriate means to constitute the first aforementioned air cushion.

 The first propeller of the propulsion system described creates, in the axis of the boat, a flow of water at a speed higher than that of the boat, thanks to its powerful suction operated at the front of the boat in place of the frontal impact normally caused on the chine, by the relative speed of the water compared to that of the boat.

 The same propeller therefore tends to move the boat forward by resting on the pressure created behind it.

 As a variant, this pressure can be further increased by the presence, near the propeller concerned and behind it, of a hydrofoil 6 advantageously inclined on the air-water interface as it is located inside said hydraulic channel 4 when the boat is partially planed. The hydrofoil contributes to partial planing even at low speeds, because it is placed permanently in contact with water on its lower face and in contact with air, under slight pressure, on its upper face. The tilt angle of the hydrofoil is not critical; it is however advantageous that it confers a maximum of force with vertical component and gives only a minimal horizontal drag.

The additional pressure then exerted behind the propeller further improves its efficiency, which tends to behave in water like a corkscrew in cork.

 A second propeller, preferably of the same type and of practically similar characteristics, placed in the hydraulic channel behind the first reproduces at a certain distance the same diagram: suction, pressure and possibly taking support on the hydrofoil. It is clear that the distance between propellers must be suitable for this and that the skilled person can determine it by routine tests within his reach. It is only necessary to specify that a propeller should not be placed at a distance which would cancel the thrust effect of the previous one, that is to say at a distance such that it draws water from the area where the previous propeller exerts its maximum thrust. The optimum seems to be that the second propeller draws water from the area where the first still exerts a significant residual pressure, in order to avoid a cavitation effect.

 For better efficiency, the second propeller is accelerated by an engine rotating at a speed higher than that of the engine of the first propeller. It is the same for the propeller of rank n vis-à-vis the propeller of rank n-i.

 A third propeller and the following possibly, once duly set in motion at controlled speed, contribute to transmitting to the boat a propulsion power whose efficiency is appreciably increased compared to the traditional scheme of rear propulsion. What has just been explained for the relative positions and the respective operating modes of the first and second propellers applies mutatis mutandis to the following.

 As for the rearward ejection of the water flow aspirated at the front, it is supported on the particular shape of the stern inherent in the hydraulic channel according to the invention and thus cancels the suction effect that the conventional hull inevitably creates. However, it is well known that this suction effect also affects the overall efficiency of the propulsion.

 The boat thus equipped advantageously comprises side skirts (not shown), or preferably side hulls 7 for a trimaran or catamaran type boat, and also a flexible yoke at the front and an orientable and almost waterproof panel at the stern. These arrangements or equivalent equipment make it possible to create a second air cushion 8 above the level of the flotation water, under the part of the hull of the boat situated on either side of said hydraulic channel.

 In Figure 3 are represented: - by I the water level at standstill, - by II the water level in operation with partial planing, and - by III the water level above the propeller in the hydraulic channel.

 In practice, we create, under a suitably equipped catamaran type hull, a first air cushion at about 1000 mm of water column inside the above-mentioned hydraulic channel or tunnel and we create, in a balancing situation with this first air cushion, a second air cushion at approximately 1700 mm water column, for example with a booster. This in practice induces a water column of approximately 70 cm in the aforementioned hydraulic channel, where the propellers are housed.

 According to the preferred embodiment, the hydraulic channel also comprises at least one hydrofoil placed behind the propellers and intended to contribute to partial planing of the boat. To this end, it is advantageous that the hydrofoils are inclined on the horizontal along an axis transverse to the main axis of the boat, so as to present a leading edge raised at an angle that the skilled person is able to to determine following tests and which may vary on a case-by-case basis. These hydrofoils can be adjustable, but they are preferably fixed. These hydrofoils should preferably be located at the air-water interface when the boat thus equipped is on the move with partial planing, in order to contribute effectively, in association with the thrust of the propeller located upstream, to the partial planing of the boat.

 The aforesaid second air cushion 8 is made almost airtight by appropriate conventional means. However, the lower part of the side skirts and / or the hulls 7 of the trimaran type boat may also be provided with vent holes as described in document EP-A-0466991.

In either case, the air cushions ensure partial planing, increase the slenderness of the boat, erase the possible planing hump and above all ensure a significant reduction in resistance to advancement, as well as reduction in wave drag and wake effect.

 The movements of the boat are controlled by means of one or more conventional rudders (not shown).

 An additional advantage of the propulsion system according to the invention and of a partial planing boat which is equipped with it is the ability to considerably reduce the duration and the constraints of crossing the locks. In fact, when going up or down, you can cancel the air cushion at the right time, before entering the airlock of the lock, then re-inflate this air cushion once the doors of the lock closed. This provides a volume of air which replaces the volume of water normally supplied by the lock keeper. This contribution makes it possible to reduce the duration of the crossing in a proportion given by the ratio between the volume of the lock and the volume of the barge or barges of this type in transit. Indeed the volume occupied by the air, such as it appears from the accompanying drawings for a barge of the Freycinet type, represents substantially half of the displacement of the boat, the emptying and filling of the air volume being carried out under the control of the pilot, before crossing the lock and during this one. However, it is known that lockage operations constitute one of the major handicaps of river navigation.

 According to another particularly preferred variant, the boat according to the invention is also provided with a device 9 for protecting the propulsive bodies against foreign bodies. A preferred embodiment of this variant consists of a fairly loose mesh net, for example in diamonds of about 5 cm × 3 cm, made of plastic or other practically rot-proof material capable of withstanding the shocks caused by floating objects of 'about 100 kg. This net preferably extends over the entire length of the aforementioned central channel or tunnel, at the base of which it is appropriately fixed by conventional means.

 Furthermore, it is advantageous, taking into account the speed of the water on the interior walls of the above-mentioned channel and on the hydrofoils, that these walls are made of treated steel, in particular steel provided with a plastic coating such as those which the he skilled in the art is able to consider as effective, that is to say for example a coating of polytetrafluoroethylene.

 The barges using the system according to the invention are advantageously specially designed for the rapid loading and unloading of 20 and 40 foot containers, which they can transport from loading centers to redistribution centers where the containers are picked up to be delivered, most often by semi-trailer trucks, to recipients.

 By way of nonlimiting example, a 300-ton barge with an air cushion and propulsion system according to the invention can carry, at a speed much higher than that allowed for this type of boat, up to 9 40-foot containers. or 18 20-foot containers, in good conditions, across the European network.

The undeniable improvement in the mechanical performance of this boat compared to existing barges makes it possible to envisage its use more specifically for a particular purpose: the rapid transport of containers. In fact, this barge can be in the form of an easily convertible tray making it possible to receive the containers on anchor pads similar to those used on trailers or large container ships
These anchoring studs, exactly positioned on the flat bottom of the barge and pneumatically controlled, allow the containers of 20 and / or 40 feet to be fixed on request on one or two levels. The shape and structure of this barge allow it to be used for the transport of vehicles or trailer trucks.

 It is also advisable, by taking advantage of the particular shape and structure of this boat, to recommend its rational layout with a view to improving its operation. For example, interchangeable control and accommodation modules (not shown) can provide mariners and their families with significant improvements, since relays and quick returns to the home port become possible.

These modules, suitably equipped and transferred whenever necessary to a return barge, make it possible to rationalize and make profitable this type of transport, reducing fatigue and downtime.

 Service and maintenance are also made easier.

 In the same way, according to a particularly preferred form of implementation, a “motor-air blower” module (not shown), placed at the rear, can be designed to be interchangeable so as to also reduce accidental immobilizations. or scheduled for maintenance. This module can thus comprise, apart from at least one diesel engine of suitable power, an alternator or a generator supplying the electrical energy intended for the electric motor-propeller assemblies whose speed and direction of rotation are in practice controlled from the "forward" cabin. The electrical control of the air boosters can be regulated, for example by frequency variation or by any other conventional means, and all of the boat's accessories are in practice under the direct control of the pilot, assisted if necessary by a programmable controller. It is expected that rudders, anchors, radars, video equipment, radios and the safety system will be powered by this electrical network assisted by a large accumulator.

 The maintenance of this assembly, including the engine-propeller assemblies, is simplified and the productivity of the barge thus equipped is considerably increased.

 The propulsion systems and the boats which are provided with them according to the present invention make it possible in summary to: profit from inland waterway navigation, even in the current state of the "Freycinet" network, rationalize the general economy of the transport of various goods and offer for the inevitable development of this traffic a solution other than transport by heavy trucks, necessarily inducing considerable investments and nuisances.

Claims (8)

 1. Improved propulsion system for boats, characterized in that it comprises at least three propulsive members (1) arranged in line in the longitudinal axis of the boat, inside a hydraulic channel or tunnel (4), and combined with: - means for generating a first air cushion (5) above the water level in said hydraulic channel and - means for generating a second air cushion (8) above the water level flotation, under the part of the hull (7) of the boat located on either side of said hydraulic channel.  2. propulsion system according to claim 1, characterized in that it comprises a plurality of propulsive members (1) preferably of the naval propeller type, driven by an appropriate engine (2) and distributed along the longitudinal axis of the boat , the first of these propellers being advantageously located at the bow of the boat, set back from the funnel formed by the bow or the double bow or from the front flexible screed for partitioning the air cushion under the hull, while the following are arranged aft, at a certain distance from it, the last being preferably located near the stern of the boat.  3. propulsion system according to one of claims 1 or 2, characterized in that the first propeller of the propulsion system creates, in the axis of the boat, a flow of water at a speed greater than that of the boat and causes the boat taking support on the pressure created behind it, a second propeller placed in the hydraulic channel behind the first reproduces at a certain distance the same diagram: suction, pressure and possibly taking support on the hydrofoil, a third propeller and the following possibly, once duly set in motion at a controlled speed, contribute to transmitting to the boat a propulsion power whose efficiency is appreciably increased compared to the conventional scheme of rear propulsion, and the ejection towards the rear of the flow of water sucked in front is supported by the particular shape of the stern inherent in the hydraulic channel.  4. propulsion system according to any one of claims 1 to 3, characterized in that it further comprises a hydraulic channel or tunnel (4) defined by a longitudinal lining (4, '4' ', 4 "') substantially in an inverted U of an appropriate width so that it can surround the propellers laterally and surmounting them so that a volume of air (5) remains above them, when they are in their submerged position.  5. propulsion system according to claim 4, characterized in that said volume of air (5) is put under overpressure by suitable means to constitute the first air cushion.  6. Boat comprising a propulsion system according to any one of claims 1 to 5, characterized in that are combined with the propulsive bodies of hydrofoils disposed aft thereof, suitably under the hull of the boat and in a position corresponding to the air-water interface when the boat is moving.  7. Boat according to claim 6, characterized in that it comprises side skirts or side hulls (7) for a trimaran or catamaran type boat, and also a flexible yoke at the front and a swiveling and almost panel waterproof in stern, thus creating a second air cushion (8) above the water level, under the part of the boat hull located on either side of said hydraulic channel.  8. Boat according to one of claims 6 or 7, characterized in that it is also provided with a device (9) for protecting the propulsive organs against foreign bodies.