CA2271034C - Dual propeller propulsion system for a water craft - Google Patents
Dual propeller propulsion system for a water craft Download PDFInfo
- Publication number
- CA2271034C CA2271034C CA002271034A CA2271034A CA2271034C CA 2271034 C CA2271034 C CA 2271034C CA 002271034 A CA002271034 A CA 002271034A CA 2271034 A CA2271034 A CA 2271034A CA 2271034 C CA2271034 C CA 2271034C
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- CA
- Canada
- Prior art keywords
- propeller
- drive
- accordance
- watercraft
- shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H21/00—Use of propulsion power plant or units on vessels
- B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
- B63H21/17—Use of propulsion power plant or units on vessels the vessels being motor-driven by electric motor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H23/00—Transmitting power from propulsion power plant to propulsive elements
- B63H23/22—Transmitting power from propulsion power plant to propulsive elements with non-mechanical gearing
- B63H23/24—Transmitting power from propulsion power plant to propulsive elements with non-mechanical gearing electric
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H25/00—Steering; Slowing-down otherwise than by use of propulsive elements; Dynamic anchoring, i.e. positioning vessels by means of main or auxiliary propulsive elements
- B63H25/42—Steering or dynamic anchoring by propulsive elements; Steering or dynamic anchoring by propellers used therefor only; Steering or dynamic anchoring by rudders carrying propellers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
- B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
- B63H5/08—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
- B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
- B63H5/08—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller
- B63H5/10—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
- B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
- B63H5/125—Arrangements on vessels of propulsion elements directly acting on water of propellers movably mounted with respect to hull, e.g. adjustable in direction, e.g. podded azimuthing thrusters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
- B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
- B63H5/08—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller
- B63H5/10—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type
- B63H2005/103—Arrangements on vessels of propulsion elements directly acting on water of propellers of more than one propeller of coaxial type, e.g. of counter-rotative type of co-rotative type, i.e. rotating in the same direction, e.g. twin propellers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H5/00—Arrangements on vessels of propulsion elements directly acting on water
- B63H5/07—Arrangements on vessels of propulsion elements directly acting on water of propellers
- B63H5/125—Arrangements on vessels of propulsion elements directly acting on water of propellers movably mounted with respect to hull, e.g. adjustable in direction, e.g. podded azimuthing thrusters
- B63H2005/1254—Podded azimuthing thrusters, i.e. podded thruster units arranged inboard for rotation about vertical axis
- B63H2005/1258—Podded azimuthing thrusters, i.e. podded thruster units arranged inboard for rotation about vertical axis with electric power transmission to propellers, i.e. with integrated electric propeller motors
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- High-Pressure Fuel Injection Pump Control (AREA)
- Fluid-Pressure Circuits (AREA)
- Auxiliary Drives, Propulsion Controls, And Safety Devices (AREA)
- Laying Of Electric Cables Or Lines Outside (AREA)
Abstract
A watercraft drive for a watercraft having front and rear propellers respectively mounted on a drive shaft in coaxial longitudinally-displaced relationship, each of the propellers having at least two blades; the front and rear propellers having equal diameters and being driven at like rotational velocities. The central portion of the rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross-section, is designed to optimize the jet energy exiting the front propeller. The rear propeller has an annular area extending from the central portion to its outer circumference, designed with the same design as characterizes the front propeller. The annular area of the rear propeller receives a flow of surrounding ambient water.
Description
DUEL PROPELLER PROPULSION SYSTEM FOR A WATERCRAFT
The present invention pertains to a hydrojet with a drive unit and novel twin propellers, driven by the drive unit.
Such drives are known with a design wherein the drive unit proper, for example a diesel engine, is arranged within the hull and a transmission, being another part of the drive unit, is located in a gondola under the hull. From the hull shafts are led out at mutually opposite ends; the shafts being connected to the transmission and, at their outer ends, to one of two propellers shown as identical propellers, rotating in unison with them. Such a solution is described in DE 44 40 738 A1, in which an essential feature is a control device, which is arranged between the two propellers and eliminates the twist in the water after it leaves the propeller that is the front propeller in the direction of travel, so that this water flows to the propeller that is the rear propeller in the direction of travel with a higher energy, but likewise without twist, as it does to the front propeller. The control device is formed by guide blades and a shaft, which connects the gondola or the underwater housing to the hull. Such a drive is also described with some additional information in the publicaton "The Motorship", October 1996, pages 47 and 48:
"Double The Prons: Half The Problem." This additional information includes the comment that the gondola is optimized to facilitate flow, however, no further details are given as to what is meant thereby. In any event, from the entire context it can be seen that the gondola supports the control device in its flow-facilitating design not, however, a part of the control device, which means that no comments are made from which one could come to the conclusion that the gondola does not act so as to functionally support the control device. Furthermore, despite the relatively detailed description of the propulsion system, no particulars are given about the design of the blades of the second propeller in direction of flow. The additional particulars merely include that the same propeller size of another one to improve effectiveness is possible due to a special geometry that was developed for the back propeller without any indication about what distinguishes this special geometry. Propulsion systems of this type are also known in another form, i.e.
the entire propulsion system is located in the aforementioned gondola. In this solution, an electromotor for the propellers is given as a driving motor at both ends of the gondola, to which electric energy is conveyed. Such a solution is described in EP 0 590 867 A1.
The art further recognizes that although the propellers are of equal diameter, the geometry required for the rear propeller is different for the geometry required for the first propeller because of the water flowing to the propellers, regarding pressure, flow rate, and other parameters. These geometrical requirements are well known to marine engineers and naval architects, persons skilled in the art. To design the front propeller and the different rear propeller for a particular application is readily accomplished according to known principles of marine engineering and naval architecture, and poses no problem or difficulty to those of skill in the art.
Notwithstanding the foregoing, for watercraft of this type with two propellers, coaxially driven in the same sense, cavitation and other deleterious effects still may occur.
The present invention pertains to a hydrojet with a drive unit and novel twin propellers, driven by the drive unit.
Such drives are known with a design wherein the drive unit proper, for example a diesel engine, is arranged within the hull and a transmission, being another part of the drive unit, is located in a gondola under the hull. From the hull shafts are led out at mutually opposite ends; the shafts being connected to the transmission and, at their outer ends, to one of two propellers shown as identical propellers, rotating in unison with them. Such a solution is described in DE 44 40 738 A1, in which an essential feature is a control device, which is arranged between the two propellers and eliminates the twist in the water after it leaves the propeller that is the front propeller in the direction of travel, so that this water flows to the propeller that is the rear propeller in the direction of travel with a higher energy, but likewise without twist, as it does to the front propeller. The control device is formed by guide blades and a shaft, which connects the gondola or the underwater housing to the hull. Such a drive is also described with some additional information in the publicaton "The Motorship", October 1996, pages 47 and 48:
"Double The Prons: Half The Problem." This additional information includes the comment that the gondola is optimized to facilitate flow, however, no further details are given as to what is meant thereby. In any event, from the entire context it can be seen that the gondola supports the control device in its flow-facilitating design not, however, a part of the control device, which means that no comments are made from which one could come to the conclusion that the gondola does not act so as to functionally support the control device. Furthermore, despite the relatively detailed description of the propulsion system, no particulars are given about the design of the blades of the second propeller in direction of flow. The additional particulars merely include that the same propeller size of another one to improve effectiveness is possible due to a special geometry that was developed for the back propeller without any indication about what distinguishes this special geometry. Propulsion systems of this type are also known in another form, i.e.
the entire propulsion system is located in the aforementioned gondola. In this solution, an electromotor for the propellers is given as a driving motor at both ends of the gondola, to which electric energy is conveyed. Such a solution is described in EP 0 590 867 A1.
The art further recognizes that although the propellers are of equal diameter, the geometry required for the rear propeller is different for the geometry required for the first propeller because of the water flowing to the propellers, regarding pressure, flow rate, and other parameters. These geometrical requirements are well known to marine engineers and naval architects, persons skilled in the art. To design the front propeller and the different rear propeller for a particular application is readily accomplished according to known principles of marine engineering and naval architecture, and poses no problem or difficulty to those of skill in the art.
Notwithstanding the foregoing, for watercraft of this type with two propellers, coaxially driven in the same sense, cavitation and other deleterious effects still may occur.
Accordingly, an object of the .present invention is to optimize a ship drive employing two propellers such that cavitation and other deleterious effects are substantially eliminated, and its operation is more efficient.
According to the invention, a solution lies in providing a design for the first propeller in a conventional manner, and creating a hybrid design for the second propeller.
This hybrid design consists of designing the central portion of the propeller, having a diameter substantially equal to the contraction in flow generated by the first propeller, with the conventional design for a second propeller, and peripherally outward thereof, that is from the diameter equal to the contraction in flow up to the tips of the blades, designing the second propeller in the conventional manner as the first propeller. The result is that only the central portion of the second propeller is designed differently from the first propeller to meet the constraints of the water flow, pressure, etc. coming out of the first propeller, and the outer, annular or peripheral portion beyond the diameter of water-flow contraction produced by the wake of the first propeller ~t its arrival at the second propeller, being designed the same as the first propeller.
In the drive mechanism according to the invention, both propellers have essentially the same diameter. The propeller that is the front propeller (in the direction of travel of the watercraft) has blade configurations as determined by known principles of marine engineering and naval architecture, and the propeller that is the rear propeller (in the direction of travel of the watercraft) has different blade configurations in the diameter range that is determined by the contraction of the water jet leaving the front propeller and arriving at the second propeller. These parameters are readily discernible from the principles of marine engineering and naval architecture, and readily accomplished by those of skill in the art . The rear propeller in the direction of travel of the watercraft has the same blade configuration as the first propeller in an annular area located outside the diameter range determined by the water jet contraction.
Thus, the invention relates to a watercraft drive for a watercraft having a hull, the watercraft drive having drive means including a motor having a drive shaft, front and rear propellers respectively mounted on the drive shaft in coaxial longitudinally-displaced relationship, each of the propellers having at least two blades, and the front and rear propellers having equal diameters and being driven at like rotational velocities. Control means are disposed between the front and rear propellers, for increasing the energy of a jet of water exiting the front propeller as said jet is transmitted to the rear propeller, the control means causing the water jet leaving the front propeller with both circular and axial flow components to reach the rear propeller substantially without circular components.
The control means comprises a hollow shaft having an upper end connected to the hull and a lower end, a gondola-shaped underwater housing mounted on the lower end of the hollow shaft and containing the drive means (the drive shaft extending from opposite ends of the housing), and a plurality of guide blades connected to at least one of the hollow shaft and gondola-shaped underwater housing. Power means mounted in the hull transmits power through the hollow shaft to the drive means, for rotating the front and rear propellers, the motor has a rotor covered by a motor housing, and the motor housing is connected, in heat-conducting relationship to the inside wall of the underwater housing, whereby heat from the motor is transferred to water surrounding the shaft and the underwater housing. The central portion of the rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross-section, is designed to optimize the jet energy exiting the front propeller. The rear propeller further has an annular area extending from the central portion to its outer circumference and designed with the same design as characterizes the front propeller, that annular area of the rear propeller receiving a flow of surrounding ambient water.
Preferably, the pitch of the blades in the core area of the rear propeller is 1.04 to 1.52 times the pitch of the blades in the core area of the front propeller, and the pitch of the blades in the annular area of the front propeller is between 95 percent and 105 percent of the pitch of the blades in the annular area of the rear propeller. The pitches of the blades of each of the front and rear propellers usually is in the range of 0.9 to 1.6.
The blades of the front and rear propellers may have different degrees of arcing. Preferably, the guide blades have an arc length ratio in the range of 0.0 to 0.2 and an angle of incidence in the range of -7° to +7°.
In one embodiment the control device has two guide blades which are angularly symmetrically disposed about the common axis of rotation of the front and rear propellers.
The drive means may comprise a transmission, the drive shafts extending from opposite ends thereof, and a connection shaft extending from the transmission through the hollow shaft into the hull for connection to an engine disposed therein. Alternatively, a plurality of electrical conductors can extend from the motor through the hollow shaft into the hull for connection to a source of electrical power therein. The motor also can comprise a hydraulic engine operatively connected to hydraulic fluid lines extending through the hollow shaft into the hull for connection to ~a source of hydraulic power.
The watercraft drive further may comprise an accelerating nozzle jacketing the front propeller, the accelerating nozzle having a cross-section that tapers from an inlet end upstream of the front propeller to a plane of rotation of the front propeller. Each of said front and rear propellers may be jacketed by a decelerating nozzle having a cross-section which increases from a respective nozzle inlet to a plane of rotation of the respective propeller.
In another embodiment the upper end of the hollow shaft can be rotatably mounted on the hull for enabling rotation of the underwater housing relative to the hull. The hollow shaft is rotatable about its longitudinal axis relative to the hull by as much as 360 degrees.
The watercraft drive may further comprise a front hub for fastening the front propeller to its respective drive shaft and a rear hub for fastening the rear propeller to its respective drive shaft, the front hub and rear hub being contoured for enhancing flow from the front propeller to the rear propeller.
Advantageously, the motor may be a permanently excited synchronous electric motor.
Clutch means can be provided for connecting the drive shaft to the rotor, the drive shaft passing concentrically through the rotor and extending from both ends of.the rotor for receiving the propellers which rotate in unison with it. Bearing means can be operatively mounted between the housing and the rotor. Rotor support tube means can be used to couple the drive shaft and the rotor.
In one embodiment the axis of the hollow shaft intersects and is orthogonal to the axis of the drive shaft, and the watercraft drive further comprises a carrier cone to which the upper end of the hollow shaft is connected; the housing being continuously pivotable by 360 degrees around the longitudinal axis of the hollow shaft.
Preferably, the hollow shaft and the carrier cone are mutually detachably connected in a plane of the hull.
Typically, the carrier cone has a large end and a small end having a smaller cross-section than the large end; the hollow shaft -being connected to the small end of the carrier cone and the large end of the carrier cone being connected to the watercraft within the hull. The hollow shaft can comprise one of the guide blades that are rotationally symmetrical disposed about the common axis of rotation of the front and rear propellers.
The front propeller of the watercraft drive may be jacketed by a decelerating nozzle having an inlet and a cross-section which. increases from the inlet to the plane of rotation of the propeller.
Each of the front and rear propellers can be jacketed by one of an accelerating nozzle having an inlet and a cross-section that decreases with distance from its inlet to the plane of rotation of its respective propeller, and a decelerating nozzle having an inlet and a cross-section that increases from its inlet to the plane of rotation of its respective propeller.
By another aspect each of the front and rear propellers is surrounded by either one of an accelerating nozzle having an inlet and a cross-section decreasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller, and a decelerating nozzle having a cross-section increasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller.
In a preferred embodiment the motor is an electric motor having a rotor and a stator and further comprises a first support tube connected in heat conducting relationship to the rotor, a second support tube having an inner surface connected in heat-conducting relationship to the stator and an outer surface connected in heat-conducting relationship to the underwater housing, means for connecting the shafts to the first support tube, a plurality of flanges connected in heat-conducting relationship to the underwater housing, and bearing means operatively connected between the first support tube and the flanges, whereby heat from the rotor and stator is conducted to ambient water surrounding the underwater housing and shaft for cooling the motor.
These and other features of the present invention can be better appreciated from the following description of several exemplary embodiments of the invention, and the exemplary embodiments of the invention shown in the drawings.
The drawings show:
Figure 1 shows a first embodiment of a hydrojet according to the invention, with one propeller each at the ends of a shaft led out of an underwater housing configured as a gondola so as to facilitate flow, that is arranged by means of a housing shaft or foot on the underside of a ship and accommodates an electric motor, on the shaft or ends of which a propeller each is located;
Figure 2 shows a second embodiment of another design that is advantageous compared with that of Figure 1;
Figure 3 shows a third embodiment, in which a right-angle gear drive, into which drive energy is supplied via a shafting accommodated in a jacket tube or housing shaft from an inboard drive motor, which is not shown but may be a conventional internal combustion engine, an electric motor or the like, is arranged in the underwater housing;
Figures 4, 5 and 6 each show, in representations which correspond to be above representations, a variant of an additional embodiment having an electric motor in the underwater housing, to which energy is supplied from an inboard power generator via cables that are led through the housing shaft; and 1~
Figure 7 shows a dual-propeller design which is particularly advantageous and is a twin-propeller arrangement that is especially the subject of the present invention and may be used in all the aforementioned embodiments.
Description of the embodiment according to Figure 1.
The drive comprises essentially an electric motor 1 in a housing 2 outside and especially under the hull, and two propellers, 3,4, which are driven by the electric motor 1.
The two propellers are of different designs, even though they may have tip circles 5 of equal diameter as well as a similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to arrow A. By reference to Fig. 7, it will be apparent that the stream leaving the first propeller 3, designed in conventional terms, is contracted due to known phenomenon to a diameter as shown in dotted lines, thereby arriving at the second propeller 4 in a wake or stream having a smaller diameter than the propeller 4. In the invention, the central portion of the propeller 4 is given its conventional design for a two-propeller system. However, the annular portion of propeller 4 is given the conventional design of propeller 3, and thus, is a hybrid, the central core or portion corresponding to the diameter of the contracted stream being designed conventionally as a second propeller in a two-propeller system and the annular part being conventionally designed like propeller 3. The propeller 3 that is the front propeller in the direction A
of the incoming flow has an optimal blading for increasing the energy of the flow medium. The propeller 4 that is the rear propeller in the direction A of the incoming flow has the same blading in this respect but only in the peripheral area. This peripheral area surrounds a central area, in which the blading differs from that of the front propeller 3 as described above, i.e., it once again increases the energy increased in the first propeller from this energy level after the flow medium leaving the first propeller 3 has been untwisted in a conventional control device 19 and the energy loss caused by the twist has been compensated.
The core area and the peripheral area are separated from one another by the contraction surface or interface 100.
It is possible that a jacket surface be fixed in position, which surrounds the flowing fluid after it has left the first propeller 3 and circumscribes a cross section that is markedly smaller than the whole incoming flow cross section to propeller 4. The flow medium B consequently flows to the second propeller 4 in the peripheral area in the same manner as the flow medium that is characterized by the arrows A flows to the first propeller 3.
Referring back to Figure 1, the electric motor 1 is arranged in the underwater housing 2 in a watertight manner. The driven shaft 7 is led out of it on both sides and the shaft is mounted on the side of the motor in one of two bearings 8,9 of the housing 2. Seals 10,11 to the side of the bearings 8,9 between the shaft and the front housing walls 2a,2b are used for sealing in conjunction with the front surfaces being designed as parts of labyrinth seals.
Shaft ends 12,13, each of which carries one of the two propellers 3,4, rotating in unison, are flanged on the shaft 7 outside the housing 2. On the front end, the housing 2 is joined by hub caps 14,15, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4. The front walls l4a,l5a of the boss caps 14,15 facing the housing 2 are second parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a,2b. The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot whose outer contour is part of the control device 19 between the propellers 3,4, and which has additional blades associated with the housing 2, of which a blade diametrically opposite the foot 18 is designated by reference numeral 20. On the whole, the blades of the control device 19 are affixed to the housing 2 and distributed uniformly about the longitudinal axis of the shaft 7.
The propellers 3,4 are designed such that the output energy level of the second propeller,4 is approximately equal to the final energy level of the first propeller 3 and, in conjunction with the control device 19, the output torque of the first propeller 3 as well as the input torque of the second propeller 4 are appropriately affected in a way such that only slight energy losses occur when water passes from the first to the second propeller.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in housing 2, and the inner spaces of the foot 18 and of the housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft) but also to help steer the ship, the entire drive can swivel in a known manner around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees, by appropriate reference to the ship by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
Description of the embodiment of Figure 2.
The drive essentially consists of an electric motor 1 in a housing 2 outside and below the ship's hull, and two propellers 3,4, which are driven by the electric motor 1.
The two propellers have different designs as discussed above, even though they may have tip circles 5 of equal diameter as well as similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to the arrow A.
The electric motor 1 is arranged in the underwater housing 2 in a watertight manner. The driven shaft 7 is led out of it on both sides and is mounted rotatably in one of two bearings 8, 9. Seals 10, 11 on the side of the bearings 8, 9 between the shaft 7 and the front housing walls 2a,2b are used for sealing, in conjunction with the front surfaces being designed as parts of labyrinth seals. Shaft ends 12,13, each of which carries one of the two propellers 3,4 rotating in unison, are flanged to the shaft 7 outside the housing 2. At the front end, adjoin boss caps 14,15 the housing 2, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4.
The front walls 14a,15a of the boss caps 14,15 facing the housing 2 are two parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a,2b.
The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot, whose outer contour is part of the control device 19 between the propellers 3, 4 which has additional blades associated with the housing 2, of which a blade diametrically opposite the foot 18 is designated by reference numeral 20. On the whole, the blades of the control device 19, distributed uniformly around the longitudinal axis of the shaft 7, are affixed to the housing 2.
The propellers 3,4 are designed such that the output energy level of the second propeller 4 is approximately equal to the final energy level of the first propeller 3 and, in conjunction with the control device 19, the output torque of the first propeller 3 as well as the input torque of the second propeller 4 are appropriately affected in such a way that only slight energy losses occur when liquid passes from the first to the second propeller.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in housing 2, and the inner spaces of the foot 18 and of the of housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft) but also to steer the ship, the entire drive can swivel in a known manner around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees, by appropriate reference to the ship and by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
The motor 1 is a permanent synchronous motor and thus is an electric motor with very high power capacity. Due to the technology of such a motor, it is possible to hydrodynamically configure the housing 2 between the two propellers in such a way that a very high efficiency is obtained.
With this technology it is possible for the foot 18 to be designed in the form of a shaft, so that it also will have an optimal hydrodynamic shape.
In the lower area located in the proximity of the housing 2, the shaft 18 is designed such that it forms together with a second, diametrically-opposite guide fin 20 a guide fin pair and thus a control device, so that an optimal flow of water to the propeller 4 (which is the second propeller when viewed in the direction of flow A, is possible. The guide fins end in the tip circles 5 of equal diameter of the two propellers 3,4.
By combining the permanent synchronous motor of high power density on a small diameter with optimal guide means (guide fin pair or control device 20), as well as with the two propellers 3,4 designed as described above, a drive unit is obtained which is characterized by improvement in efficiency both electrically and hydrodynamically.
The design of the motor 1 as a permanent synchronous motor makes it possible to reduce the diameter of the housing 2 by up to 20o compared with other known motors. The advantages are obvious; only more favorable flow conditions and lower flow resistance are mentioned.
Another design concerns the mounting of the rotor bearing of the permanent motor, which also contains the propeller shaft bearing. To reduce or eliminate displacements and deformations as well as the dynamic loads from the propellers, the rotor, i.e, the drive shaft 7, is connected to the propeller shafts 12,13 via disk clutches 23,24. As a result, it is possible to obtain a minimal air gap between the stator and the rotor, which means a considerable, additional improvement in efficiency.
Description of the embodiment of Figure 3.
Figure 3 shows a ship drive in the form of a rudder dual propeller having a drive motor located in the hull, with vertical drive shaft 1 and drive propellers outside the hull.
A drive unit, consisting of a motor and transmission, acts on the top end of the vertical drive shaft 1' in a conventional manner (and therefore not shown in Figure 3) in order to set the drive shaft 1 into rotation around the longitudinal axis 2 with variable speed of rotation. Input bevel gear 3 of a right-angle gear drive 3,4, which bevel gear 3 is in functional connection with the output bevel gear 4 of the right-angle gear drive 3,4, is associated with the lower end of the drive shaft 1. Output bevel gear 4 carries a horizontal output shaft 5 extending in both directions, rotating in unison with it, with the propellers 6,7 arranged at the free ends of the output shaft. The propellers usually have different designs, even though tip circles 14 of equal diameter as well as similar blade geometries are possible. Due to the joint association with the output shaft 5, they have the same direction of rotation and the same speed of rotation, and flow is directed toward them in the same direction, e.g., according to arrow A.
The right-angle gear drive 3,4 is surrounded by a housing 9 in which the output shaft 5 is mounted rotatably by means of two bearings 10,11. This housing 9 is carried by a housing tube 9a, which concentrically surrounds the vertical drive axis 1 and is pivotable around its longitudinal axis for the rudder function.
The underwater part of the drive system may be arranged within a nozzle 12.
In its wake, the front propeller 6 generates a residual or secondary twist, which represents lost energy. The wake of the front propeller is acted upon by the downstream propeller 7, rotating in the same direction. Without a guide means between the two propellers, 6,7, the above-mentioned unfavorable flow would lead to . increased cavitation and greater energy losses.
To counteract this energy loss, a guide means 8, is provided between the two propellers 6,7 with which the secondary twist of the front propeller 6 is directed. Lost energy is regained by a propulsive force being generated during the flow around the guide means. Furthermore, an initial twist is produced for the downstream propeller 7 so that the latter can realize a greater energy gradient.
Taking this into account, the second propeller 7 in its central region or diameter preferably will have a design different from that of the first propeller 6, as described above.
According to Figure 3, the guide means 8 comprises two guide blades 8a and 8b, whereby one guide blade 8a is formed by the housing tube 9a surrounding the vertical drive shaft 1. The second guide blade 8b is located on the underside 9b of the housing 9 surrounding the horizontal output shaft 5, i.e., offset by 180° from the first guide blade. The two guide blades 6,7 form a structural unit with the overall housing 9.
Description of the embodiments of Figures 4 to 6.
The drive essentially consists of an electric motor 1 in a housing 2 outside of and below the ship's hull and two propellers 3,4, which are driven by the electric motor 1.
The two propellers are of different design as explained above, even though they may have tip circles 5 of equal diameter as well as a similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to arrow A.
The electric motor is arranged in the underwater housing 2 in a watertight manner. The output end of shaft 7 is led out of it on both sides and is pivotally mounted in one of two bearings 8,9 of the housing 2 to the side of the motor.
Seals 10,11 to the side of the bearings 8,9 between the shaft 7 and the front housing walls 2a,2b are used for sealing in conjunction with the front surfaces being designed as parts of labyrinth seals. Shaft ends 12,13, each of which carries one of the two propellers 3,4, rotating in unison, are flanged on the shaft 7 outside the hour ing 2 . On the f ront end, boss caps 14 , 15 , adj oin the housing 2, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4.
The front walls 14a,15a of the boss caps 14,15 facing the housing 2 are second parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a, 2b. The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot, whose outer contour is part of the control device 19 between the propellers 3,4, which has additional blades associated with the housing 2, of which a blade located diametrically opposite the foot 18, is . designated by numeral 20 . On the whole, the blades of the control device 19 are distributed uniformly around the longitudinal axis of the shaft 7, and affixed to the housing 2.
The propellers 3,4 are designed in such a way that the output energy level of the second propeller 4 is approximately equal to the final energy level of the first propeller 3, and in association with the control device 19, the output torque of the first propeller 3 as well as the input torque to the second propeller 4, are appropriately affected in such a way that only slight energy losses occur when the liquid passes from the first to the second propeller.
When leaving the first propeller 3 the water flow has an axial component and a circumferential component. The latter component, in the circumferential direction, is deflected by guide blade 19 into the axial direction, so that the water flow entering the second propeller 4 has only components in the axial direction, similar to the water flow entering the first propeller 3, except that the flow stream has been contracted due to the increased flow rate reduced pressure, and other parameters well known in the art.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in the housing 2, and the inner spaces of the foot 18 and of the housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft), but also to help steer the ship, the entire drive is pivotable around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees by appropriate reference to the ship and by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
An especially advantageous embodiment of the propulsion system according to the invention is described below with reference to Figures 5 and 6. The electric motor 1 is advantageously, but not essentially, a permanently excited synchronous motor with permanent magnet rotor 25 and stator laminations 26. Such motors have are known, so that the electric motor, which is advantageously a permanently excited synchronous motor, as well as other suitable types of electric motors, are not described in greater detail herein.
The use of such a motor in the housing 2, which has a gondola-like design and is arranged under the hull of the ship 24, beneath the water surface, for driving the two co-rotating propellers 3,4, which face the same direction A, has various application-specific advantages, in particular in terms of electric efficiency, and it enables the omission of cooling systems. In addition, a small structural size is made possible, which in turn makes possible an optimal shape of the underwater housing with respect to resistance, especially a housing with a small maximum diameter. The gondola-shape of the housing 2 can perform a guiding function whereby the gondola-shaped housing 2 serves as part of the control device in addition to the guide fins 20 and hollow shaft or foot 18.
In order to be able to avoid forced cooling, the outer stator 26 is constructed as a laminated yoke of the electric motor 1, and is connected tightly and in direct heat contact to the underwater housing 2. The inner rotor 25 of the motor 1 is rigidly connected via support tube 27 to the rotatable shafts 12,13. In a similar way, the stator 26 is rigidly supported in the housing 2 via support tube 26' which is made of heat-conducting material, and which is firmly connected to the motor 26, as well as to the housing 2. In this arrangement there is direct heat transfer from the stator 26 of the motor (motor housing) to the support tube 26' and finally to the underwater housing 2, from which the heat is dissipated into the surrounding water flow. The underwater housing 2, the support tube 26' and the motor housing 26 are, thereby, sufficiently cooled.
The tight connection between support tube 26' and underwater housing 2, and between stator 26 and support tube 26', respectively, can be accomplished, e.g., by pressing each inner part held at lower temperature into the respective outer part held at a higher temperature. In use, at running temperature, the two parts will then be tightly connected.
For cooling the bearings 8,9 correspondingly, the bearings 8,9, which support the shafts 12,13, are in turn supported by flanges 8a,9a that are made of heat-conducting material.
The outer flange surfaces 8b,9b are tightly connected to the inner surface of the underwater housing 2 and to the motor housing 26.
In another design, such a permanently excited synchronous motor is arranged in the gondola-like housing 2 in such a way that the continuous propeller shaft 12,13 and the rotor 25 have a common mounting with the two bearings 8, 9. This is specifically realized as follows:
the permanent rotor 25 is seated on a support tube 27, which is concentrically surrounded by it and is rigidly attached to the propeller shaft 12,13, rotating in unison with it, in the vicinity of its two ends via one of two annular disk clutches 28,29 each, whereby the disk clutches 28 or 29 as well as the corresponding bearing 8 or 9 are located close to one another on both shaft ends. Due to the propeller shaft and the electric motor tube having a common mounting, the number of components is minimized and the reliability of the drive unit is increased. By using disk clutches located in close proximity to the respective radial bearing, an accurate centering of the rotor, which is to a great extent independent of propeller shaft deflection, is obtained. This results in considerable advantages with respect to the dynamic behavior of the rotor within the motor (e.g., structure-borne noise is minimized).
Likewise as a consequence of the electric motor being designed as a permanently excited synchronous motor 1 (Figures 2,3), integration of the underwater housing shaft 18 (called a "foot" in connection with Figure 1) in the propulsion system is possible in an especially advantageous manner. This housing shaft may be quite slender; as a result of which the flow resistance of the unit is considerably reduced. This slender underwater housing shaft 18 has such a cross-sectional profile that an additional untwisting of the wake of the front propeller 3 is achieved in conjunction with a lateral guide fin pair (not shown) offset by 90 degrees each, the geometry of the housing 2, and the opposite guide fin 20, which is offset by 180 degrees. This results in an improvement in efficiency of the propulsion system with two co-rotating propellers which are essentially the same and rotate the same (in terms of speed of rotation and direction of rotation) otherwise designed to the criteria specified above.
A locking brake for fixing the propeller shaft 12,13 and thus the assembly unit, whose parts include the propeller shaft, is arranged within the underwater gondola 2 and is designated by reference numeral 33.
Finally, the design according to Figures 5,6 leads to a substantial simplification of the underwater assembly.
Rudder propellers that can be assembled/disassembled with the ship floating are offered by various rudder propeller manufacturers. The corresponding assembly effort is still considerable. The present invention makes possible, especially in the embodiment according to Figures 5 and 6, a simplified underwater assembly/dismantling at the underwater housing shaft/carrier cone separation point.
The underwater housing shaft is also designated by the reference number 18 in Figure 6; its upper end lies in the plane 24 of the ship's shell and is connected to the carrier cone 30. At the upper end, the carrier cone is mounted in a control bearing 31 in the supporting structure of a ship. This control bearing 31 has an inner ring 31a with an internal gear 31b, and this bearing inner ring 31a is rigidly fixed to the outer periphery of the carrier cone 30. Outer ring 31c cooperates with the inner ring via the rolling bodies and it is rigidly integrated into the support structure of the ship. The pinion (not shown) of a driving mechanism (not shown) engages the internal gear of the inner ring of the control bearing, so that the entire driving mechanism can be rotated by 360 degrees around the longitudinal axis 22 to steer the ship.
The detachable connection between the housing shaft 18 and the carrier cone 30 is symbolized by a flange connection 32.
Common to all embodiments is the combination of the features claimed, according to which the propulsion system is a hydrojet for watercraft, especially ships, which has a driving motor and two propellers driven by same, which propellers are arranged at the two ends of a gondola-like, streamlined underwater housing outside and are driven by a driving mechanism which is situated inside the underwater housing and acts on a drive shaft common to both propellers, whereby the first propeller markedly increases the flow energy of the flow medium and this flow medium is conveyed with a high energy content, after eliminating the inevitable aftertwist in a guide means, to the second propeller, which differs from the first propeller in terms of its blading such that the relatively low flow energy in the first propeller is optimally increased, while the relatively high flow energy is increased further in the second propeller. In a special embodiment, described below on the basis of Figure 7, the second propeller is a hybrid design that has a central part which differs from the first propeller in the manner described, and a peripheral part which is similar to the first propeller to this extent and to which the medium flows in the same manner as to the first propeller.
Description of the embodiment of Figure 7.
As previously mentioned, the front propeller 3 in the direction A of the incoming flow has an optimal blading for increasing the energy of the flow medium. The back propeller 4 in the direction A of the incoming flow has a similar blading in this respect in a peripheral area. This peripheral area surrounds a central area in which the blading differs from that of the front propeller 3 as described above, i.e., it increases the energy increased in the first propeller from this level after the flow medium leaving the first propeller 3 has been untwisted in the control device 19 and the energy loss caused by the twist has been compensated. The core area and the peripheral area are separated from one another by the contraction surface 100, of the flowing contracted stream, i.e. by the jacket surface or casing that surrounds the flowing liquid after it has left the first propeller 3 and circumscribes a cross section that is markedly smaller, substantially contracted, than the incoming flow cross-section.
Consequently, in the peripheral area, the flow medium B
flows to the second propeller in the same manner as the flow medium that is characterized by the arrow A flows to the first propeller.
According to the invention, a solution lies in providing a design for the first propeller in a conventional manner, and creating a hybrid design for the second propeller.
This hybrid design consists of designing the central portion of the propeller, having a diameter substantially equal to the contraction in flow generated by the first propeller, with the conventional design for a second propeller, and peripherally outward thereof, that is from the diameter equal to the contraction in flow up to the tips of the blades, designing the second propeller in the conventional manner as the first propeller. The result is that only the central portion of the second propeller is designed differently from the first propeller to meet the constraints of the water flow, pressure, etc. coming out of the first propeller, and the outer, annular or peripheral portion beyond the diameter of water-flow contraction produced by the wake of the first propeller ~t its arrival at the second propeller, being designed the same as the first propeller.
In the drive mechanism according to the invention, both propellers have essentially the same diameter. The propeller that is the front propeller (in the direction of travel of the watercraft) has blade configurations as determined by known principles of marine engineering and naval architecture, and the propeller that is the rear propeller (in the direction of travel of the watercraft) has different blade configurations in the diameter range that is determined by the contraction of the water jet leaving the front propeller and arriving at the second propeller. These parameters are readily discernible from the principles of marine engineering and naval architecture, and readily accomplished by those of skill in the art . The rear propeller in the direction of travel of the watercraft has the same blade configuration as the first propeller in an annular area located outside the diameter range determined by the water jet contraction.
Thus, the invention relates to a watercraft drive for a watercraft having a hull, the watercraft drive having drive means including a motor having a drive shaft, front and rear propellers respectively mounted on the drive shaft in coaxial longitudinally-displaced relationship, each of the propellers having at least two blades, and the front and rear propellers having equal diameters and being driven at like rotational velocities. Control means are disposed between the front and rear propellers, for increasing the energy of a jet of water exiting the front propeller as said jet is transmitted to the rear propeller, the control means causing the water jet leaving the front propeller with both circular and axial flow components to reach the rear propeller substantially without circular components.
The control means comprises a hollow shaft having an upper end connected to the hull and a lower end, a gondola-shaped underwater housing mounted on the lower end of the hollow shaft and containing the drive means (the drive shaft extending from opposite ends of the housing), and a plurality of guide blades connected to at least one of the hollow shaft and gondola-shaped underwater housing. Power means mounted in the hull transmits power through the hollow shaft to the drive means, for rotating the front and rear propellers, the motor has a rotor covered by a motor housing, and the motor housing is connected, in heat-conducting relationship to the inside wall of the underwater housing, whereby heat from the motor is transferred to water surrounding the shaft and the underwater housing. The central portion of the rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross-section, is designed to optimize the jet energy exiting the front propeller. The rear propeller further has an annular area extending from the central portion to its outer circumference and designed with the same design as characterizes the front propeller, that annular area of the rear propeller receiving a flow of surrounding ambient water.
Preferably, the pitch of the blades in the core area of the rear propeller is 1.04 to 1.52 times the pitch of the blades in the core area of the front propeller, and the pitch of the blades in the annular area of the front propeller is between 95 percent and 105 percent of the pitch of the blades in the annular area of the rear propeller. The pitches of the blades of each of the front and rear propellers usually is in the range of 0.9 to 1.6.
The blades of the front and rear propellers may have different degrees of arcing. Preferably, the guide blades have an arc length ratio in the range of 0.0 to 0.2 and an angle of incidence in the range of -7° to +7°.
In one embodiment the control device has two guide blades which are angularly symmetrically disposed about the common axis of rotation of the front and rear propellers.
The drive means may comprise a transmission, the drive shafts extending from opposite ends thereof, and a connection shaft extending from the transmission through the hollow shaft into the hull for connection to an engine disposed therein. Alternatively, a plurality of electrical conductors can extend from the motor through the hollow shaft into the hull for connection to a source of electrical power therein. The motor also can comprise a hydraulic engine operatively connected to hydraulic fluid lines extending through the hollow shaft into the hull for connection to ~a source of hydraulic power.
The watercraft drive further may comprise an accelerating nozzle jacketing the front propeller, the accelerating nozzle having a cross-section that tapers from an inlet end upstream of the front propeller to a plane of rotation of the front propeller. Each of said front and rear propellers may be jacketed by a decelerating nozzle having a cross-section which increases from a respective nozzle inlet to a plane of rotation of the respective propeller.
In another embodiment the upper end of the hollow shaft can be rotatably mounted on the hull for enabling rotation of the underwater housing relative to the hull. The hollow shaft is rotatable about its longitudinal axis relative to the hull by as much as 360 degrees.
The watercraft drive may further comprise a front hub for fastening the front propeller to its respective drive shaft and a rear hub for fastening the rear propeller to its respective drive shaft, the front hub and rear hub being contoured for enhancing flow from the front propeller to the rear propeller.
Advantageously, the motor may be a permanently excited synchronous electric motor.
Clutch means can be provided for connecting the drive shaft to the rotor, the drive shaft passing concentrically through the rotor and extending from both ends of.the rotor for receiving the propellers which rotate in unison with it. Bearing means can be operatively mounted between the housing and the rotor. Rotor support tube means can be used to couple the drive shaft and the rotor.
In one embodiment the axis of the hollow shaft intersects and is orthogonal to the axis of the drive shaft, and the watercraft drive further comprises a carrier cone to which the upper end of the hollow shaft is connected; the housing being continuously pivotable by 360 degrees around the longitudinal axis of the hollow shaft.
Preferably, the hollow shaft and the carrier cone are mutually detachably connected in a plane of the hull.
Typically, the carrier cone has a large end and a small end having a smaller cross-section than the large end; the hollow shaft -being connected to the small end of the carrier cone and the large end of the carrier cone being connected to the watercraft within the hull. The hollow shaft can comprise one of the guide blades that are rotationally symmetrical disposed about the common axis of rotation of the front and rear propellers.
The front propeller of the watercraft drive may be jacketed by a decelerating nozzle having an inlet and a cross-section which. increases from the inlet to the plane of rotation of the propeller.
Each of the front and rear propellers can be jacketed by one of an accelerating nozzle having an inlet and a cross-section that decreases with distance from its inlet to the plane of rotation of its respective propeller, and a decelerating nozzle having an inlet and a cross-section that increases from its inlet to the plane of rotation of its respective propeller.
By another aspect each of the front and rear propellers is surrounded by either one of an accelerating nozzle having an inlet and a cross-section decreasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller, and a decelerating nozzle having a cross-section increasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller.
In a preferred embodiment the motor is an electric motor having a rotor and a stator and further comprises a first support tube connected in heat conducting relationship to the rotor, a second support tube having an inner surface connected in heat-conducting relationship to the stator and an outer surface connected in heat-conducting relationship to the underwater housing, means for connecting the shafts to the first support tube, a plurality of flanges connected in heat-conducting relationship to the underwater housing, and bearing means operatively connected between the first support tube and the flanges, whereby heat from the rotor and stator is conducted to ambient water surrounding the underwater housing and shaft for cooling the motor.
These and other features of the present invention can be better appreciated from the following description of several exemplary embodiments of the invention, and the exemplary embodiments of the invention shown in the drawings.
The drawings show:
Figure 1 shows a first embodiment of a hydrojet according to the invention, with one propeller each at the ends of a shaft led out of an underwater housing configured as a gondola so as to facilitate flow, that is arranged by means of a housing shaft or foot on the underside of a ship and accommodates an electric motor, on the shaft or ends of which a propeller each is located;
Figure 2 shows a second embodiment of another design that is advantageous compared with that of Figure 1;
Figure 3 shows a third embodiment, in which a right-angle gear drive, into which drive energy is supplied via a shafting accommodated in a jacket tube or housing shaft from an inboard drive motor, which is not shown but may be a conventional internal combustion engine, an electric motor or the like, is arranged in the underwater housing;
Figures 4, 5 and 6 each show, in representations which correspond to be above representations, a variant of an additional embodiment having an electric motor in the underwater housing, to which energy is supplied from an inboard power generator via cables that are led through the housing shaft; and 1~
Figure 7 shows a dual-propeller design which is particularly advantageous and is a twin-propeller arrangement that is especially the subject of the present invention and may be used in all the aforementioned embodiments.
Description of the embodiment according to Figure 1.
The drive comprises essentially an electric motor 1 in a housing 2 outside and especially under the hull, and two propellers, 3,4, which are driven by the electric motor 1.
The two propellers are of different designs, even though they may have tip circles 5 of equal diameter as well as a similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to arrow A. By reference to Fig. 7, it will be apparent that the stream leaving the first propeller 3, designed in conventional terms, is contracted due to known phenomenon to a diameter as shown in dotted lines, thereby arriving at the second propeller 4 in a wake or stream having a smaller diameter than the propeller 4. In the invention, the central portion of the propeller 4 is given its conventional design for a two-propeller system. However, the annular portion of propeller 4 is given the conventional design of propeller 3, and thus, is a hybrid, the central core or portion corresponding to the diameter of the contracted stream being designed conventionally as a second propeller in a two-propeller system and the annular part being conventionally designed like propeller 3. The propeller 3 that is the front propeller in the direction A
of the incoming flow has an optimal blading for increasing the energy of the flow medium. The propeller 4 that is the rear propeller in the direction A of the incoming flow has the same blading in this respect but only in the peripheral area. This peripheral area surrounds a central area, in which the blading differs from that of the front propeller 3 as described above, i.e., it once again increases the energy increased in the first propeller from this energy level after the flow medium leaving the first propeller 3 has been untwisted in a conventional control device 19 and the energy loss caused by the twist has been compensated.
The core area and the peripheral area are separated from one another by the contraction surface or interface 100.
It is possible that a jacket surface be fixed in position, which surrounds the flowing fluid after it has left the first propeller 3 and circumscribes a cross section that is markedly smaller than the whole incoming flow cross section to propeller 4. The flow medium B consequently flows to the second propeller 4 in the peripheral area in the same manner as the flow medium that is characterized by the arrows A flows to the first propeller 3.
Referring back to Figure 1, the electric motor 1 is arranged in the underwater housing 2 in a watertight manner. The driven shaft 7 is led out of it on both sides and the shaft is mounted on the side of the motor in one of two bearings 8,9 of the housing 2. Seals 10,11 to the side of the bearings 8,9 between the shaft and the front housing walls 2a,2b are used for sealing in conjunction with the front surfaces being designed as parts of labyrinth seals.
Shaft ends 12,13, each of which carries one of the two propellers 3,4, rotating in unison, are flanged on the shaft 7 outside the housing 2. On the front end, the housing 2 is joined by hub caps 14,15, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4. The front walls l4a,l5a of the boss caps 14,15 facing the housing 2 are second parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a,2b. The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot whose outer contour is part of the control device 19 between the propellers 3,4, and which has additional blades associated with the housing 2, of which a blade diametrically opposite the foot 18 is designated by reference numeral 20. On the whole, the blades of the control device 19 are affixed to the housing 2 and distributed uniformly about the longitudinal axis of the shaft 7.
The propellers 3,4 are designed such that the output energy level of the second propeller,4 is approximately equal to the final energy level of the first propeller 3 and, in conjunction with the control device 19, the output torque of the first propeller 3 as well as the input torque of the second propeller 4 are appropriately affected in a way such that only slight energy losses occur when water passes from the first to the second propeller.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in housing 2, and the inner spaces of the foot 18 and of the housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft) but also to help steer the ship, the entire drive can swivel in a known manner around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees, by appropriate reference to the ship by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
Description of the embodiment of Figure 2.
The drive essentially consists of an electric motor 1 in a housing 2 outside and below the ship's hull, and two propellers 3,4, which are driven by the electric motor 1.
The two propellers have different designs as discussed above, even though they may have tip circles 5 of equal diameter as well as similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to the arrow A.
The electric motor 1 is arranged in the underwater housing 2 in a watertight manner. The driven shaft 7 is led out of it on both sides and is mounted rotatably in one of two bearings 8, 9. Seals 10, 11 on the side of the bearings 8, 9 between the shaft 7 and the front housing walls 2a,2b are used for sealing, in conjunction with the front surfaces being designed as parts of labyrinth seals. Shaft ends 12,13, each of which carries one of the two propellers 3,4 rotating in unison, are flanged to the shaft 7 outside the housing 2. At the front end, adjoin boss caps 14,15 the housing 2, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4.
The front walls 14a,15a of the boss caps 14,15 facing the housing 2 are two parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a,2b.
The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot, whose outer contour is part of the control device 19 between the propellers 3, 4 which has additional blades associated with the housing 2, of which a blade diametrically opposite the foot 18 is designated by reference numeral 20. On the whole, the blades of the control device 19, distributed uniformly around the longitudinal axis of the shaft 7, are affixed to the housing 2.
The propellers 3,4 are designed such that the output energy level of the second propeller 4 is approximately equal to the final energy level of the first propeller 3 and, in conjunction with the control device 19, the output torque of the first propeller 3 as well as the input torque of the second propeller 4 are appropriately affected in such a way that only slight energy losses occur when liquid passes from the first to the second propeller.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in housing 2, and the inner spaces of the foot 18 and of the of housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft) but also to steer the ship, the entire drive can swivel in a known manner around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees, by appropriate reference to the ship and by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
The motor 1 is a permanent synchronous motor and thus is an electric motor with very high power capacity. Due to the technology of such a motor, it is possible to hydrodynamically configure the housing 2 between the two propellers in such a way that a very high efficiency is obtained.
With this technology it is possible for the foot 18 to be designed in the form of a shaft, so that it also will have an optimal hydrodynamic shape.
In the lower area located in the proximity of the housing 2, the shaft 18 is designed such that it forms together with a second, diametrically-opposite guide fin 20 a guide fin pair and thus a control device, so that an optimal flow of water to the propeller 4 (which is the second propeller when viewed in the direction of flow A, is possible. The guide fins end in the tip circles 5 of equal diameter of the two propellers 3,4.
By combining the permanent synchronous motor of high power density on a small diameter with optimal guide means (guide fin pair or control device 20), as well as with the two propellers 3,4 designed as described above, a drive unit is obtained which is characterized by improvement in efficiency both electrically and hydrodynamically.
The design of the motor 1 as a permanent synchronous motor makes it possible to reduce the diameter of the housing 2 by up to 20o compared with other known motors. The advantages are obvious; only more favorable flow conditions and lower flow resistance are mentioned.
Another design concerns the mounting of the rotor bearing of the permanent motor, which also contains the propeller shaft bearing. To reduce or eliminate displacements and deformations as well as the dynamic loads from the propellers, the rotor, i.e, the drive shaft 7, is connected to the propeller shafts 12,13 via disk clutches 23,24. As a result, it is possible to obtain a minimal air gap between the stator and the rotor, which means a considerable, additional improvement in efficiency.
Description of the embodiment of Figure 3.
Figure 3 shows a ship drive in the form of a rudder dual propeller having a drive motor located in the hull, with vertical drive shaft 1 and drive propellers outside the hull.
A drive unit, consisting of a motor and transmission, acts on the top end of the vertical drive shaft 1' in a conventional manner (and therefore not shown in Figure 3) in order to set the drive shaft 1 into rotation around the longitudinal axis 2 with variable speed of rotation. Input bevel gear 3 of a right-angle gear drive 3,4, which bevel gear 3 is in functional connection with the output bevel gear 4 of the right-angle gear drive 3,4, is associated with the lower end of the drive shaft 1. Output bevel gear 4 carries a horizontal output shaft 5 extending in both directions, rotating in unison with it, with the propellers 6,7 arranged at the free ends of the output shaft. The propellers usually have different designs, even though tip circles 14 of equal diameter as well as similar blade geometries are possible. Due to the joint association with the output shaft 5, they have the same direction of rotation and the same speed of rotation, and flow is directed toward them in the same direction, e.g., according to arrow A.
The right-angle gear drive 3,4 is surrounded by a housing 9 in which the output shaft 5 is mounted rotatably by means of two bearings 10,11. This housing 9 is carried by a housing tube 9a, which concentrically surrounds the vertical drive axis 1 and is pivotable around its longitudinal axis for the rudder function.
The underwater part of the drive system may be arranged within a nozzle 12.
In its wake, the front propeller 6 generates a residual or secondary twist, which represents lost energy. The wake of the front propeller is acted upon by the downstream propeller 7, rotating in the same direction. Without a guide means between the two propellers, 6,7, the above-mentioned unfavorable flow would lead to . increased cavitation and greater energy losses.
To counteract this energy loss, a guide means 8, is provided between the two propellers 6,7 with which the secondary twist of the front propeller 6 is directed. Lost energy is regained by a propulsive force being generated during the flow around the guide means. Furthermore, an initial twist is produced for the downstream propeller 7 so that the latter can realize a greater energy gradient.
Taking this into account, the second propeller 7 in its central region or diameter preferably will have a design different from that of the first propeller 6, as described above.
According to Figure 3, the guide means 8 comprises two guide blades 8a and 8b, whereby one guide blade 8a is formed by the housing tube 9a surrounding the vertical drive shaft 1. The second guide blade 8b is located on the underside 9b of the housing 9 surrounding the horizontal output shaft 5, i.e., offset by 180° from the first guide blade. The two guide blades 6,7 form a structural unit with the overall housing 9.
Description of the embodiments of Figures 4 to 6.
The drive essentially consists of an electric motor 1 in a housing 2 outside of and below the ship's hull and two propellers 3,4, which are driven by the electric motor 1.
The two propellers are of different design as explained above, even though they may have tip circles 5 of equal diameter as well as a similar blade geometry. They have the same direction of rotation and the same speed of rotation, and the flow is directed toward them in the same direction, e.g., according to arrow A.
The electric motor is arranged in the underwater housing 2 in a watertight manner. The output end of shaft 7 is led out of it on both sides and is pivotally mounted in one of two bearings 8,9 of the housing 2 to the side of the motor.
Seals 10,11 to the side of the bearings 8,9 between the shaft 7 and the front housing walls 2a,2b are used for sealing in conjunction with the front surfaces being designed as parts of labyrinth seals. Shaft ends 12,13, each of which carries one of the two propellers 3,4, rotating in unison, are flanged on the shaft 7 outside the hour ing 2 . On the f ront end, boss caps 14 , 15 , adj oin the housing 2, whereby a continuous flow-facilitating outer contour with head 14 is formed in the area of the front propeller 3, the middle part in the form of the housing 2 and the end part 15 in the area of the rear propeller 4.
The front walls 14a,15a of the boss caps 14,15 facing the housing 2 are second parts of the labyrinth seals 16,17, whose first parts are the aforementioned front surfaces 2a, 2b. The housing 2 is held at the hull with a foot 18, which is designed as a hollow foot, whose outer contour is part of the control device 19 between the propellers 3,4, which has additional blades associated with the housing 2, of which a blade located diametrically opposite the foot 18, is . designated by numeral 20 . On the whole, the blades of the control device 19 are distributed uniformly around the longitudinal axis of the shaft 7, and affixed to the housing 2.
The propellers 3,4 are designed in such a way that the output energy level of the second propeller 4 is approximately equal to the final energy level of the first propeller 3, and in association with the control device 19, the output torque of the first propeller 3 as well as the input torque to the second propeller 4, are appropriately affected in such a way that only slight energy losses occur when the liquid passes from the first to the second propeller.
When leaving the first propeller 3 the water flow has an axial component and a circumferential component. The latter component, in the circumferential direction, is deflected by guide blade 19 into the axial direction, so that the water flow entering the second propeller 4 has only components in the axial direction, similar to the water flow entering the first propeller 3, except that the flow stream has been contracted due to the increased flow rate reduced pressure, and other parameters well known in the art.
Energy is supplied to the electric motor by lines 21, which are led to the motor in the foot 18 and in the housing 2, and the inner spaces of the foot 18 and of the housing 2 are connected to one another.
To make it possible to use the drive not only to generate a thrust in the longitudinal direction of the ship (longitudinal axis of the drive shaft), but also to help steer the ship, the entire drive is pivotable around the vertical longitudinal axis 22 in the middle between the two propellers, optionally all around by 360 degrees by appropriate reference to the ship and by means of an appropriate pivoting mechanism, the axis 22 being directed at right angles to the axis of rotation of the longitudinal axis 23 of the shaft.
An especially advantageous embodiment of the propulsion system according to the invention is described below with reference to Figures 5 and 6. The electric motor 1 is advantageously, but not essentially, a permanently excited synchronous motor with permanent magnet rotor 25 and stator laminations 26. Such motors have are known, so that the electric motor, which is advantageously a permanently excited synchronous motor, as well as other suitable types of electric motors, are not described in greater detail herein.
The use of such a motor in the housing 2, which has a gondola-like design and is arranged under the hull of the ship 24, beneath the water surface, for driving the two co-rotating propellers 3,4, which face the same direction A, has various application-specific advantages, in particular in terms of electric efficiency, and it enables the omission of cooling systems. In addition, a small structural size is made possible, which in turn makes possible an optimal shape of the underwater housing with respect to resistance, especially a housing with a small maximum diameter. The gondola-shape of the housing 2 can perform a guiding function whereby the gondola-shaped housing 2 serves as part of the control device in addition to the guide fins 20 and hollow shaft or foot 18.
In order to be able to avoid forced cooling, the outer stator 26 is constructed as a laminated yoke of the electric motor 1, and is connected tightly and in direct heat contact to the underwater housing 2. The inner rotor 25 of the motor 1 is rigidly connected via support tube 27 to the rotatable shafts 12,13. In a similar way, the stator 26 is rigidly supported in the housing 2 via support tube 26' which is made of heat-conducting material, and which is firmly connected to the motor 26, as well as to the housing 2. In this arrangement there is direct heat transfer from the stator 26 of the motor (motor housing) to the support tube 26' and finally to the underwater housing 2, from which the heat is dissipated into the surrounding water flow. The underwater housing 2, the support tube 26' and the motor housing 26 are, thereby, sufficiently cooled.
The tight connection between support tube 26' and underwater housing 2, and between stator 26 and support tube 26', respectively, can be accomplished, e.g., by pressing each inner part held at lower temperature into the respective outer part held at a higher temperature. In use, at running temperature, the two parts will then be tightly connected.
For cooling the bearings 8,9 correspondingly, the bearings 8,9, which support the shafts 12,13, are in turn supported by flanges 8a,9a that are made of heat-conducting material.
The outer flange surfaces 8b,9b are tightly connected to the inner surface of the underwater housing 2 and to the motor housing 26.
In another design, such a permanently excited synchronous motor is arranged in the gondola-like housing 2 in such a way that the continuous propeller shaft 12,13 and the rotor 25 have a common mounting with the two bearings 8, 9. This is specifically realized as follows:
the permanent rotor 25 is seated on a support tube 27, which is concentrically surrounded by it and is rigidly attached to the propeller shaft 12,13, rotating in unison with it, in the vicinity of its two ends via one of two annular disk clutches 28,29 each, whereby the disk clutches 28 or 29 as well as the corresponding bearing 8 or 9 are located close to one another on both shaft ends. Due to the propeller shaft and the electric motor tube having a common mounting, the number of components is minimized and the reliability of the drive unit is increased. By using disk clutches located in close proximity to the respective radial bearing, an accurate centering of the rotor, which is to a great extent independent of propeller shaft deflection, is obtained. This results in considerable advantages with respect to the dynamic behavior of the rotor within the motor (e.g., structure-borne noise is minimized).
Likewise as a consequence of the electric motor being designed as a permanently excited synchronous motor 1 (Figures 2,3), integration of the underwater housing shaft 18 (called a "foot" in connection with Figure 1) in the propulsion system is possible in an especially advantageous manner. This housing shaft may be quite slender; as a result of which the flow resistance of the unit is considerably reduced. This slender underwater housing shaft 18 has such a cross-sectional profile that an additional untwisting of the wake of the front propeller 3 is achieved in conjunction with a lateral guide fin pair (not shown) offset by 90 degrees each, the geometry of the housing 2, and the opposite guide fin 20, which is offset by 180 degrees. This results in an improvement in efficiency of the propulsion system with two co-rotating propellers which are essentially the same and rotate the same (in terms of speed of rotation and direction of rotation) otherwise designed to the criteria specified above.
A locking brake for fixing the propeller shaft 12,13 and thus the assembly unit, whose parts include the propeller shaft, is arranged within the underwater gondola 2 and is designated by reference numeral 33.
Finally, the design according to Figures 5,6 leads to a substantial simplification of the underwater assembly.
Rudder propellers that can be assembled/disassembled with the ship floating are offered by various rudder propeller manufacturers. The corresponding assembly effort is still considerable. The present invention makes possible, especially in the embodiment according to Figures 5 and 6, a simplified underwater assembly/dismantling at the underwater housing shaft/carrier cone separation point.
The underwater housing shaft is also designated by the reference number 18 in Figure 6; its upper end lies in the plane 24 of the ship's shell and is connected to the carrier cone 30. At the upper end, the carrier cone is mounted in a control bearing 31 in the supporting structure of a ship. This control bearing 31 has an inner ring 31a with an internal gear 31b, and this bearing inner ring 31a is rigidly fixed to the outer periphery of the carrier cone 30. Outer ring 31c cooperates with the inner ring via the rolling bodies and it is rigidly integrated into the support structure of the ship. The pinion (not shown) of a driving mechanism (not shown) engages the internal gear of the inner ring of the control bearing, so that the entire driving mechanism can be rotated by 360 degrees around the longitudinal axis 22 to steer the ship.
The detachable connection between the housing shaft 18 and the carrier cone 30 is symbolized by a flange connection 32.
Common to all embodiments is the combination of the features claimed, according to which the propulsion system is a hydrojet for watercraft, especially ships, which has a driving motor and two propellers driven by same, which propellers are arranged at the two ends of a gondola-like, streamlined underwater housing outside and are driven by a driving mechanism which is situated inside the underwater housing and acts on a drive shaft common to both propellers, whereby the first propeller markedly increases the flow energy of the flow medium and this flow medium is conveyed with a high energy content, after eliminating the inevitable aftertwist in a guide means, to the second propeller, which differs from the first propeller in terms of its blading such that the relatively low flow energy in the first propeller is optimally increased, while the relatively high flow energy is increased further in the second propeller. In a special embodiment, described below on the basis of Figure 7, the second propeller is a hybrid design that has a central part which differs from the first propeller in the manner described, and a peripheral part which is similar to the first propeller to this extent and to which the medium flows in the same manner as to the first propeller.
Description of the embodiment of Figure 7.
As previously mentioned, the front propeller 3 in the direction A of the incoming flow has an optimal blading for increasing the energy of the flow medium. The back propeller 4 in the direction A of the incoming flow has a similar blading in this respect in a peripheral area. This peripheral area surrounds a central area in which the blading differs from that of the front propeller 3 as described above, i.e., it increases the energy increased in the first propeller from this level after the flow medium leaving the first propeller 3 has been untwisted in the control device 19 and the energy loss caused by the twist has been compensated. The core area and the peripheral area are separated from one another by the contraction surface 100, of the flowing contracted stream, i.e. by the jacket surface or casing that surrounds the flowing liquid after it has left the first propeller 3 and circumscribes a cross section that is markedly smaller, substantially contracted, than the incoming flow cross-section.
Consequently, in the peripheral area, the flow medium B
flows to the second propeller in the same manner as the flow medium that is characterized by the arrow A flows to the first propeller.
Claims (27)
1. A watercraft drive for a watercraft having a hull, the watercraft drive having:
drive means including a motor having a drive shaft, front and rear propellers respectively mounted on the drive shaft in coaxial longitudinally-displaced relationship, each of the propellers having at least two blades, said front and rear propellers having equal diameters and being driven at like rotational velocities;
control means disposed between said front and rear propellers, for increasing the energy of a jet of water exiting the front propeller as said jet is transmitted to the rear propeller, said control means causing the water jet leaving the front propeller with both circular and axial flow components to reach the rear propeller substantially without circular components, said control means comprising a hollow shaft having an upper end connected to said hull and a lower end, a gondola-shaped underwater housing mounted on the lower end of said hollow shaft and containing said drive means, said drive shaft extending from opposite ends of said housing, and a plurality of guide blades connected to at least one of said hollow shaft and gondola-shaped underwater housing;
power means mounted in said hull for transmitting power through said hollow shaft to said drive means for rotating said front and rear propellers, said motor having a rotor covered by a motor housing, and said motor housing being connected in heat-conducting relationship to the inside wall of said underwater housing whereby heat from said motor is transferred to water surrounding said shaft and said underwater housing;
and wherein the central portion of said rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross-section, is designed to optimize the jet energy exiting the front propeller, said rear propeller further having an annular area extending from said central portion to its outer circumference designed with the same design as characterizes the front propeller, said annular area of the rear propeller receiving a flow of surrounding ambient water.
drive means including a motor having a drive shaft, front and rear propellers respectively mounted on the drive shaft in coaxial longitudinally-displaced relationship, each of the propellers having at least two blades, said front and rear propellers having equal diameters and being driven at like rotational velocities;
control means disposed between said front and rear propellers, for increasing the energy of a jet of water exiting the front propeller as said jet is transmitted to the rear propeller, said control means causing the water jet leaving the front propeller with both circular and axial flow components to reach the rear propeller substantially without circular components, said control means comprising a hollow shaft having an upper end connected to said hull and a lower end, a gondola-shaped underwater housing mounted on the lower end of said hollow shaft and containing said drive means, said drive shaft extending from opposite ends of said housing, and a plurality of guide blades connected to at least one of said hollow shaft and gondola-shaped underwater housing;
power means mounted in said hull for transmitting power through said hollow shaft to said drive means for rotating said front and rear propellers, said motor having a rotor covered by a motor housing, and said motor housing being connected in heat-conducting relationship to the inside wall of said underwater housing whereby heat from said motor is transferred to water surrounding said shaft and said underwater housing;
and wherein the central portion of said rear propeller up to a diameter equal to the diameter of the water jet arriving at the rear propeller, which due to the action of the front propeller has a contracted cross-section, is designed to optimize the jet energy exiting the front propeller, said rear propeller further having an annular area extending from said central portion to its outer circumference designed with the same design as characterizes the front propeller, said annular area of the rear propeller receiving a flow of surrounding ambient water.
2. A watercraft drive in accordance with claim 1, wherein the pitch of the blades in the core area of the rear propeller is 1.04 to 1.52 times the pitch of the blades in the core area of the front propeller.
3. A watercraft drive in accordance with claim 2, wherein the pitch of the blades in the annular area of the front propeller is between 95 percent and 105 percent of the pitch of the blades in the annular area of the rear propeller.
4. A watercraft drive in accordance with claim 2, wherein the pitches of the blades of each of the front and rear propellers is in the range of 0.9 to 1.6.
5. A watercraft drive in accordance with claim 2, wherein the blades of the front and rear propellers have different degrees of arcing.
6. A watercraft drive in accordance with any one of claims 1 to 5, wherein said guide blades which have an arc length ratio in the range of 0.0 to 0.2 and an angle of incidence in the range of -7° to +7°.
7. A watercraft drive in accordance with claim 6, wherein the control device has two guide blades which are angularly symmetrically disposed about the common axis of rotation of the front and rear propellers.
8. A watercraft drive in accordance with any one of claims 1 to 7, wherein the drive means further comprises a transmission, said drive shaft extends from opposite ends thereof, and a connection shaft extends from said transmission through said hollow shaft into said hull for connection to an engine disposed therein.
9. A watercraft drive in accordance with any one of claims 1 to 7, further comprising a plurality of electrical conductors extending from said motor through said hollow shaft into said hull for connection to a source of electrical power therein.
10. A watercraft drive in accordance with any one of claims 1 to 7, wherein said motor comprises a hydraulic engine operatively connected to hydraulic fluid lines extending through said hollow shaft into said hull for connection to a source of hydraulic power.
11. A watercraft drive in accordance with any one of claims 1 to 10, further comprising an accelerating nozzle jacketing the front propeller, said accelerating nozzle having a cross-section which tapers from an inlet end upstream of the front propeller to a plane of rotation of the front propeller.
12. A watercraft drive in accordance with any one of claims 1 to 10, wherein each of said front and rear propellers is jacketed by a decelerating nozzle having a cross-section which increases from a respective nozzle inlet to a plane of rotation of the respective propeller.
13. A watercraft drive in accordance with any one of claims 1 to 12, wherein the upper end of the hollow shaft is rotatably mounted on the hull for enabling rotation of the underwater housing relative to the hull.
14. A watercraft drive in accordance with claim 13, wherein the hollow shaft is rotatable about its longitudinal axis relative to the hull by 360 degrees.
15. A watercraft drive in accordance with any one of claims 1 to 14, further comprising a front hub for fastening the front propeller to its respective drive shaft and a rear hub for fastening the rear propeller to its respective drive shaft, the front hub and rear hub being contoured for enhancing flow from the front propeller to the rear propeller.
16. A watercraft drive in accordance with any one of claims 1 to 9, wherein the motor is a permanently excited synchronous electric motor.
17. A watercraft drive in accordance with claim 16, further comprising clutch means for connecting said drive shaft to said rotor, said drive shaft passing concentrically through the rotor and extending from both ends of the rotor for receiving the propellers which rotate in unison with said drive shaft.
18. A watercraft drive in accordance with claim 17, further comprising bearing means operatively mounted between said housing and said rotor.
19. A watercraft drive in accordance with claim 15, further comprising rotor support tube means for coupling said drive shaft and said rotor.
20. A watercraft drive in accordance with claim 14, wherein the axis of the hollow shaft intersects and is orthogonal to the axis of the drive shaft, and further comprising a carrier cone to which the upper end of the hollow shaft is connected, the housing being continuously pivotable by 360 degrees around the longitudinal axis of the hollow shaft.
21. A watercraft drive in accordance with claim 20, wherein the hollow shaft and the carrier cone are mutually detachably connected in a plane of the hull.
22. A watercraft drive in accordance with claim 20 or 21, wherein the carrier cone has a large end and a small end having a smaller cross-section than said large end, the hollow shaft being connected to the small end of the carrier cone and the large. end of the carrier cone being connected to the watercraft within the hull.
23 A watercraft drive in accordance with claim 7, wherein the hollow shaft comprises one of said guide blades that are rotationally symmetrical disposed about the common axis of rotation of the front and rear propellers.
24. A watercraft drive in accordance with any one of claims 1 to 10, wherein the front propeller is jacketed by a decelerating nozzle having an inlet and a cross-section which increases from the inlet to the plane of rotation of the propeller.
25. A watercraft drive in accordance with any one of claims 1 to 10, wherein each of the font and rear propellers is jacketed by one of an accelerating nozzle having an inlet and a cross-section that decreases with distance from its inlet to the plane of rotation of its respective propeller, and a decelerating nozzle having an inlet and a cross-section that increases from its inlet to the plane of rotation of its respective propeller.
26. A watercraft drive in accordance with any one of claims 1 to 10, wherein each of the front and rear propellers is surrounded by either one of an accelerating nozzle having an inlet and a cross-section decreasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller, and a decelerating nozzle having a cross-section increasing with distance from the inlet of the nozzle toward the plane of rotation of the first propeller.
27. A watercraft drive in accordance with any one of claims 1 to 10, wherein said motor is an electric motor having a rotor and a stator, and further comprising a first support tube connected in heat-conducting relationship to said rotor, a second support tube having an inner surface connected in heat-conducting relationship to said stator and an outer surface connected in heat-conducting relationship to said underwater housing, means for connecting said shafts to said first support tube, a plurality of flanges connected in heat-conducting relationship to said underwater housing, and bearing means operatively connected between said first support tube and said flanges, whereby heat from said rotor and stator is conducted to ambient water surrounding said underwater housing and shaft for cooling said motor.
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE29619385.2 | 1996-11-07 | ||
| DE29619385U DE29619385U1 (en) | 1996-11-07 | 1996-11-07 | Ship propulsion with a rudder propeller |
| DE19648417.0 | 1996-11-22 | ||
| DE1996148417 DE19648417A1 (en) | 1996-11-22 | 1996-11-22 | Double-propeller drive for water vessel |
| DE29707028.2 | 1997-04-18 | ||
| DE29707028U DE29707028U1 (en) | 1996-11-07 | 1997-04-18 | Ship propulsion with a rudder propeller |
| PCT/EP1997/006207 WO1998019907A1 (en) | 1996-11-07 | 1997-11-07 | Dual propeller propulsion system for a water craft |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2271034A1 CA2271034A1 (en) | 1998-05-14 |
| CA2271034C true CA2271034C (en) | 2004-06-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002271034A Expired - Fee Related CA2271034C (en) | 1996-11-07 | 1997-11-07 | Dual propeller propulsion system for a water craft |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0935553B1 (en) |
| JP (1) | JP3214568B2 (en) |
| KR (1) | KR100306261B1 (en) |
| CN (1) | CN1080677C (en) |
| CA (1) | CA2271034C (en) |
| DK (1) | DK0935553T3 (en) |
| ES (1) | ES2163204T3 (en) |
| HK (1) | HK1023971A1 (en) |
| NO (1) | NO324212B1 (en) |
| PT (1) | PT935553E (en) |
| WO (1) | WO1998019907A1 (en) |
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| FI96590B (en) | 1992-09-28 | 1996-04-15 | Kvaerner Masa Yards Oy | Ship's propulsion device |
| JPH07132469A (en) | 1993-11-08 | 1995-05-23 | Kaijirushi Hamono Kaihatsu Center:Kk | Handle for various tools and manufacture thereof |
| DE4440138C1 (en) * | 1994-11-10 | 1996-01-25 | Volker Wagner | Mounting for holding candles, e.g. during mfr., transport or storage |
| DE4440738A1 (en) * | 1994-11-15 | 1996-05-23 | Schottel Werft | Ship propulsion with a prime mover in the hull and a propeller driven by the prime mover outside the hull |
| JPH08207895A (en) * | 1995-02-06 | 1996-08-13 | Ishikawajima Harima Heavy Ind Co Ltd | Steering device for ship |
| DE19618247A1 (en) * | 1996-05-07 | 1997-11-13 | Blohm & Voss Int | Propeller drive for marine vessel |
| DE29619385U1 (en) * | 1996-11-07 | 1997-03-13 | Schottel-Werft Josef Becker GmbH & Co KG, 56322 Spay | Ship propulsion with a rudder propeller |
-
1997
- 1997-11-07 DK DK97950145T patent/DK0935553T3/en active
- 1997-11-07 PT PT97950145T patent/PT935553E/en unknown
- 1997-11-07 EP EP97950145A patent/EP0935553B1/en not_active Expired - Lifetime
- 1997-11-07 ES ES97950145T patent/ES2163204T3/en not_active Expired - Lifetime
- 1997-11-07 JP JP52107598A patent/JP3214568B2/en not_active Expired - Fee Related
- 1997-11-07 WO PCT/EP1997/006207 patent/WO1998019907A1/en active IP Right Grant
- 1997-11-07 CA CA002271034A patent/CA2271034C/en not_active Expired - Fee Related
- 1997-11-07 CN CN97199553A patent/CN1080677C/en not_active Expired - Fee Related
-
1999
- 1999-05-04 KR KR1019997003942A patent/KR100306261B1/en not_active IP Right Cessation
- 1999-05-06 NO NO19992215A patent/NO324212B1/en not_active IP Right Cessation
-
2000
- 2000-05-24 HK HK00103085A patent/HK1023971A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JP3214568B2 (en) | 2001-10-02 |
| WO1998019907A1 (en) | 1998-05-14 |
| JP2000515095A (en) | 2000-11-14 |
| DK0935553T3 (en) | 2002-01-28 |
| EP0935553A1 (en) | 1999-08-18 |
| PT935553E (en) | 2002-03-28 |
| NO324212B1 (en) | 2007-09-10 |
| CA2271034A1 (en) | 1998-05-14 |
| CN1080677C (en) | 2002-03-13 |
| ES2163204T3 (en) | 2002-01-16 |
| KR100306261B1 (en) | 2001-09-24 |
| CN1236347A (en) | 1999-11-24 |
| HK1023971A1 (en) | 2000-09-29 |
| EP0935553B1 (en) | 2001-09-19 |
| NO992215L (en) | 1999-05-06 |
| NO992215D0 (en) | 1999-05-06 |
| KR20000053042A (en) | 2000-08-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20141107 |