Arrangement for adjusting the pitch angle of a propeller in an electric propulsion system
The system optimally adjusts propeller pitch using two electric motors and a claw clutch for efficient kinetic energy recovery and accumulator charging, addressing inefficiencies in existing systems.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- OCEANVOLT
- Filing Date
- 2026-01-14
- Publication Date
- 2026-07-23
AI Technical Summary
Existing electric propulsion systems in sailing vessels with fixed-blade propellers inefficiently recover kinetic energy, leading to insufficient charging of accumulators, and existing adjustable propeller systems either hinder vessel movement or have suboptimal efficiency ratios, especially when reversing or generating electricity.
A system using two concentric electric motors with an angle gearbox and a claw clutch to adjust the propeller pitch angle optimally for forward drive, reverse, and generating electricity, allowing for efficient kinetic energy recovery and accumulator charging.
Enables self-sufficiency of sailing vessels during normal sailing trips by fully charging accumulators with kinetic energy, providing optimal thrust, minimal resistance, and efficient energy generation.
Smart Images
Figure FI2026050014_23072026_PF_FP_ABST
Abstract
Description
[0001] ARRANGEMENT FOR ADJUSTING THE PITCH ANGLE OF A PROPELLER IN AN ELECTRIC PROPULSION SYSTEM
[0002] The object of the invention is an arrangement as defined in the independent claim for adjusting the pitch angle of a propeller in an electric propulsion system . The arrangement is particularly, but not exclusively, suited for use in sailing vessels .
[0003] The arrangement according to the invention for adjusting the pitch angle of a propeller in an electric propulsion system, i . e . the solution according to the invention, is particularly well suited for use e . g . as a solution charging the accumulators of a sailing vessel in a kinetic energy recovery arrangement for sailing vessels or sailing ships , hereinafter jointly referred to as sailing vessels , when the sailing vessel moves by means of sails . In this case the electric motor of the traction device of a sailing vessel is used as a generator recovering kinetic energy via a propeller . When suitably regulated, a sailing vessel can function for long periods of time fully self-sufficiently, receiving the electrical energy it needs for recharging accumulators via the electric motor of the traction device when moving by means of the sails .
[0004] Known in the art are electric propulsion arrangements for a sailing vessel , in which the kinetic energy obtained by means of the sails of the sailing vessel is utilized by means of the electric motor of the traction device by using the electric motor as a generator when the propeller is rotating from the force of the movement of the sailing vessel to charge the accumulators of the electric motor . One problem is , however, that in those types of tractiondevices in which fixed-blade propellers are used, the kinetic energy of the sailing vessel is not sufficiently well recovered, and the accumulators of the sailing vessel are thus not charged sufficiently fully during a sailing journey of normal duration . The reason for this is that fixed-blade propellers certainly convey a vessel forwards with an adequately high efficiency ratio, but in a charging situation with the flow coming to the propeller from the other side than the intended one, the geometry of the blades of a fixed-blade propeller is such that the efficiency ratio from the viewpoint of recovered kinetic energy is extremely bad . In this case, separate additional generators or solar panels must be used to safeguard the electric drive of the sailing vessel , or the accumulators must be charged at quays , which must perhaps be visited more often than normal just for charging the accumulators . In addition, this type of fixed-blade propeller brakes the passage of the sailing vessel when under sail , so that in practice the use of fixed-blade propellers in the traction devices of sailing vessels is not recommended .
[0005] Also known in the art are electrical propulsion arrangements for sailing vessels wherein the propeller blades of the traction device are folded backwards when the sailing vessel is traveling under the force of the sails . In this case the propeller hinders the forward movement of the sailing vessel as little as possible . A consequence of this , however, is that the propeller is not then very capable of gathering kinetic energy from the force of the movement of the sailing vessel when using the electric motor of the traction device as a generator . A type of propeller arrangement has , however, been developed as a solution to this , wherein the propeller blades are foldedbackwards during quite slow travel speeds , but the more the travel speed increases , the more the blades turn open from the effect of the centrifugal force produced by a faster speed of rotation, in which case the recovery of kinetic energy improves . This type of solution is used particularly in fast multi-hull sailing vessels because the sailing speed of single-hull vessels is too low for this type of solution .
[0006] Also known in the art are electrical propulsion arrangements for a sailing vessel wherein the propeller blades of the traction device turn from the force of the flow into the direction of the flow . In this case the propeller hinders the travel motion of the sailing vessel when sailing as little as possible . When driving forwards the propeller blades settle into a predetermined position that enables reaching a sufficiently good efficiency ratio when driving forwards . Correspondingly, when driving in reverse the propeller blades settle, when changing the direction of rotation of the propeller shaft , approx . 180 degrees forwards from the drive position into a position that enables reaching an efficiency ratio that is essentially equal to when driving forwards . From the viewpoint of the functionality of the system, however, the shape of the propeller blades cannot be optimal in this solution . A consequence of this is that although this is , in practice, a functional and widely-used solution and kinetic energy recovery for charging the accumulators of a vessel is associated with it , the kinetic energy recovery is not so good in terms of its efficiency ratio that a sailing vessel could be fully self-sufficient with the accumulators charged by means of kinetic energy recoveredduring sailing journeys that are just the normal daily sailing trips in length .
[0007] In order to recover energy from the kinetic energy achieved by means of the sails at a sufficiently high efficiency ratio, the efficiency ratio of the propeller blades would have to be as good as possible also in the direction opposite to the normal drive direction . This requires a controllable pitch angle for the propeller blades . A controllable pitch angle for the propeller blades is known in the art from, inter alia, ship propellers in which the pitch angles of the blades are adjusted, e . g . between 0-60 degrees , for improving the efficiency ratio of forward movement . This type of adjusting movement is not , however, sufficient for using the propeller to rotate a generator, because the efficiency ratio of the propeller does not improve sufficiently in motion in a direction that is opposite to the normal movement direction . For this , a propeller solution would be needed in which the adjustment angle of the blades would be at least 180 degrees , preferably even more than that . These types of effective propeller solutions that recover the kinetic energy of a sailing vessel in the traction devices of sailing vessels are not known in the art to exist .
[0008] A solution is , however, known from United States patent no . US5554003A wherein an adjustment angle of the blades is revealed that is at its maximum approx . 180 degrees . In this solution, however, the same shaft with which the propeller is rotated is used for adjusting the angle of the propeller blades . In the propeller hub is a stop mechanism, which limits the extreme positions of pitch angles between forward and reverse movement and also generator use to atleast 120 degrees and preferably to approx . 180 degrees . When the direction is changed, the propeller shaft first rotates a part of a revolution without the propeller rotating . In this case the propeller shaft rotates from the first limit to the second limit of the stop mechanism, or vice versa . On this rotation the propeller shaft changes the pitch angle . When the detent of the propeller shaft reaches either extreme position limit , the pitch angle is correct for the next working motion and the propeller starts to operate in the opposite direction . These extreme positions function sufficiently well , but one problem is that the propeller blades do not remain in their correct attitude between the extreme positions , for example when it is desired to drive with free sailing and minimum friction without the propeller blades receiving resistance . Since the position of the pitch angles is not adjustable, but instead they adjust themselves between the extreme positions , the solution cannot be optimized e . g . from the viewpoint of the recovery of kinetic energy . In addition, from the viewpoint of the functionality of the system, the shape of the propeller blades cannot be optimal , so the solution of the aforementioned patent is not sufficiently good in terms of its efficiency ratio for adequately efficient charging of the accumulators of sailing vessels .
[0009] A solution is known from international patent publication no . WO2005012078A1 wherein the propeller is rotated on a hollow shaft , inside which is a push rod rotating along with the hollow shaft , which rod is moved axially either forwards or backwards for adjusting the pitch angles of the propeller . Inside the propeller hub is a lever mechanism for changing the axial movement of the push rod for adjusting the pitch angles into rotary movement . It is not ,however, possible with the axial movement of the push rod to bring about such a large adjustment movement of the pitch angles that the propeller could be used at a sufficient efficiency ratio for rotating the motor as a generator . The magnitude of the adjustment of the pitch angles is not even mentioned in the publication . The purpose in the solution according to the WO publication is , in fact , only to adjust the pitch angles in such a way that forward travel is achieved as efficiently as possible .
[0010] Yet another solution is known from United States patent no . US3795463A, in which is a control for propeller blades intended for ships , wherein a separate multipart shaft controlling the blades is inside a hollow shaft that rotates the propeller . The controlling shaft is rotated with a servomotor from the end of the controlling shaft , the servomotor being fixed to the housing of a separate angular gearing unit , which gearing unit is connected to the second end of the propeller shaft to transmit rotational movement of the drive motor of the traction device to the propeller shaft . The drive shaft of the servomotor is connected via a complex gearing arrangement to a first extension of the controlling shaft extending from the second end of the propeller shaft , by rotating which extension a coupling means in the propeller hub on the second extension of the controlling shaft is moved in the axial direction for adjusting the pitch angles of the propeller blades . The problem here also is the axial movement of the controlling shaft ; the axial movement not bringing about a pitch angle control movement that is large enough for forward travel , reverse travel and, particularly, rotation of the motor as a generator to be sufficiently efficient . For this reason the structure isunusable in electrical propulsion . One further problem is the complex structure of the gearing arrangement on the second end of the propeller shaft , that is made complex by, inter alia, the fact that the gearing structure must enable use of the servomotor fixed rigidly into position on the gearing housing without the servomotor rotating along with the propeller shaft during drive or reversing . Most of the gear wheels of the reduction gear always rotate, increasing the friction, reducing the efficiency ratio of charging, and requiring splash lubrication . In addition, the structure has many parts that require servicing . This solution is not economically viable in leisure craft .
[0011] Known in the art from Russian patent publication no . RU2236986C2 is a solution for controlling the pitch angles of propeller blades wherein inside the hollow propeller shaft is a pitch angle control rod, a servomotor and reduction gearing functioning as a reduction gear . The servomotor rotates the control rod in relation to the propeller shaft and the adjustment position of the blades is monitored with an electromechanical sensor suited to the purpose . The publication mentions that the servomotor is rigidly fixed inside the hollow propeller shaft , but the fixing solution is not described in more detail . The publication also does not describe the connection of the control shaft to the mechanism in the propeller hub for adjusting the propeller blades , nor the connection of the drive motor rotating the propeller shaft to the propeller shaft . In solutions known in the art the drive motor is generally at one of the two ends of the propeller shaft , which solution is not actually presented in this publication . It is to be assumed that in this solution also the drive motor is at the second end of the propeller shaftbecause there was no space there for the servomotor, which had to be disposed inside the propeller shaft . A problem is , inter alia, that gaining access to the servomotor that is inside the propeller shaft , e . g . when servicing or repair is needed, is difficult . In addition, installing the servomotor inside the propeller shaft is awkward and timeconsuming . One further problem is that , owing to the servomotor, the propeller shaft must always be made disadvantageously large in diameter at least at the point of the servomotor and gearing . Another problem is the unfavourably long structure, particularly in an angular gearing application, because the motor, reduction gear and blade control are consecutive and in a straight line, i . e . in practice one on top of the other .
[0012] The aim of this invention is to eliminate the aforementioned drawbacks and to provide an arrangement for adjusting the pitch angle of a propeller in an electric propulsion system, i . e . more briefly a solution, in which it is possible to control the pitch angle of the propeller in such a way that the position of the blades is optimal in forward drive, in reverse and also in free sailing, as well as when using the electric motor of the traction device as a generator for charging the accumulators of the sailing vessel . Another aim is to provide a solution in which it is possible to recover as much energy as possible from the kinetic energy of the travel motion achieved by means of the sails for charging the accumulators of the sailing vessel at a good efficiency ratio . Another aim is to make the recovery of the kinetic energy of travel motion obtained by means of the sails so effective that a sailing vessel can be self-sufficient in relation to charging the accumulators also when only resorting to the chargingenergy collected during sailing sessions of normal duration . The solution according to the invention for adjusting the pitch angle of a propeller in an electric propulsion system is characterized by what is disclosed in the characterization part of the independent claim . Other embodiments of the invention are characterized by what is disclosed in the other claims .
[0013] One advantage of the solution according to the invention is the capability of recovering the kinetic energy of the travel motion of a sailing vessel achieved by means of the sails with such a good efficiency ratio that with sailing sessions of normal duration the sailing vessel can be self-sufficient in terms of electricity usage, because the accumulators of sailing vessels can be fully charged with even short sailing sessions when the sailing vessel travels by means of the sails . A further advantage is the easy and flexible, and also optimal , adjustment of the propeller blades also for other purposes than just charging the accumulators , i . e . as a result of the solution according to the invention, optimal thrust is enabled in forward drive and in reversing, optimal free running is achieved, and also optimal generation of charging current is achieved when using the electric motor of the traction device as a generator during sailing . Another advantage is also the easy installation and service-friendliness of the servomotor that is at the end of the propeller shaft on the outside of the shaft . One advantage is also a simple and operationally reliable structure that is advantageous in terms of costs . The solution according to the invention is very advantageously suitable in conjunction with sailing vessels , although not limited to these but instead is also suited for adjusting the pitch angle of a propeller inmotor vessels . The solution is suited for use in both the underwater parts of vessels , such as in various pods , as well as in structures above the waterline, such as in conventional motor vessels .
[0014] In the following, the invention will be described in greater detail by the aid of some embodiments and by referring to the attached simplified drawings , wherein
[0015] Fig . 1 presents a simplified drawing of a preferred embodiment of the arrangement for adjusting the pitch angle of a propeller,
[0016] Fig . 2 presents a preferred embodiment of a clutch arrangement between the electric motors , Fig . 3 presents a second preferred embodiment of a claw clutch arranged between the electric motors , and Fig . 4 presents a simplified schematic drawing of the settling of the claw clutch into its feathering position .
[0017] Fig . 1 presents a simplified drawing of a preferred embodiment of the adjustment of the pitch angle of a propeller 1 . The propeller 1 comprises the hub of the propeller (not presented in Fig . 1 for the sake of clarity) and blades 2 adjustably fastened to the hub . In this embodiment the propeller 1 has three adjustable blades 2 (all visible) . The arrangement for adjusting the pitch angle of the propeller 1 comprises two electric motors 3 and 4 disposed consecutively . The first electric motor 3 is disposed closer to the propeller 1 and it is connected to the propeller blades 2 with an angle gearbox 10 on the first shaft 5 . The angle gearbox 10 connects the first electric motor 3 to the corresponding bevel gears 7 of thepropeller blades 2 of the first shaft via the bevel gear 6 fastened to the outer end of the first shaft 5 in such a way that it is possible by means of the first electric motor 3 to adjust the pitch angle of the propeller by changing the phase difference of the first electric motor 3 and the second electric motor 4 .
[0018] The first shaft 5 is hollow . A second shaft 8 is disposed inside the hollow first shaft 5 , which second shaft connects the second electric motor 4 , situated farther from the propeller to the hub of the propeller 1 . In this embodiment , this second electric motor 4 is only used to rotate the propeller 1 via the second shaft 8 . The electric motors 3 and 4 are therefore situated concentrically one after the other .
[0019] The angle gearbox 10 thus preferably comprises bevel gears 7 fastened to each blade 2 of the propeller 1 as well as a corresponding bevel gear 6 fastened to the first shaft 5 of the first electric motor 3 . The electric motors 3 and 4 are driven with motor controllers (not presented in the figures ) and are kept in the same phase, in which case the pitch angle of the propeller 1 does not change . The position of the shafts 5 and 8 of the electric motors 3 and 4 in relation to each other is monitored with position sensors (not presented in the figures ) , which measure the position ratio of the electric motors , i . e . the angular difference or phase difference . When changing the phase difference between electric motors 3 and 4 , the pitch angle of the propeller 1 is adjusted at the same time by means of the angular gear 10 . The adjustment can be made in either direction whatsoever, steplessly and without any restrictions on the amount of change in the adjustablepitch angle . The sensitivity of the adjustment of the pitch angle of the propeller 1 occurring with a phase difference can be changed by placing a reduction gear on one or both electric motors 3 and 4 . Alternatively, it is also possible to implement the solution with different electric motors , in which case the rotation speed of the second electric motor can be e . g . 10 times that of the first motor . Also the power outputs of the electric motors may be of different magnitudes .
[0020] The advantage of two consecutive electric motors is that their physical dimensions fit better, especially when placed in the underwater pod of a sailing vessel , which makes the long and narrow solution hydrodynamically advantageous . In practice, the manufacture of one long electric motor is not advantageous , because the currents in the windings of the electric motor rise too high and may cause the windings to burn out . When the solution is implemented with two consecutive electric motors , the power outputs of the motors can be combined and at the same time the pitch angle of the propeller can be adjusted . The solution presented above can be implemented e . g . in a 48V system in such a way that the solution has two 25 kW electric motors , in which case their current is 600A and the combined power output is 2 x 25 kW = 50 kW . If the 50kW power outputs were taken with one electric motor, the current would rise to over 1000A . This kind of solution is difficult to implement also because of , inter alia, the availability of motor controllers .
[0021] In Figure 1 , an angle gearbox 10 adjusting the pitch angle of the propeller 1 is disposed between the propeller and the first shaft 5 of the first electric motor 3 . Accordingto another preferred embodiment , the second shaft 8 of the second electric motor 4 , said shaft fastened to the hub of the propeller 1 and only rotating the propeller, can alternatively be brought through the propeller hub to the other side of the propeller and the corresponding second angle gearbox can also be disposed on the opposite side of the propeller than that presented in Fig . 1 . This second angle gearbox therefore comprises a bevel gear fastened to the shaft 8 passing through the hub of the propeller 1 , which gear engages with the bevel gears 7 of the propeller blades in the direction of the shafts 5 and 8 of the electric motors 3 and 4 from the opposite side than that of the bevel gear 6 of the first shaft 4 . In this case, both the shafts 5 and 8 of the electric motors 3 and 4 can be combined by means of angle gearboxes for the adjustment of the pitch angle of the propeller 1 and for bringing about a differential gear for the adjustment of the pitch angle of the propeller by changing the phase difference of the electric motors .
[0022] The solution according to Fig . 1 can also be used to produce electricity by hydrogenerating when e . g . a sailing vessel is running with sails . In such a case, a braking torque is applied to the second electric motor 4 , which allows the energy produced by the propeller 1 to be recovered . By adjusting the pitch angle the hydrogeneration yield can be maximized . The electricity generated is at its maximum, 25 kW, in the case of the previous example, in which there are two 25kW motors .
[0023] Fig . 2 presents a preferred embodiment of the claw clutch 11 arranged between the electric motors 3 and 4 . Thus a clutch arrangement 30 is disposed between the firstelectric motor 3 and the second electric motor 4 . The clutch arrangement 30 comprises a freely rotating clutch piece with protrusions 12 (claws ) parallel to the shafts 5 and 8 of the electric motors 3 and 4 on both sides of the clutch piece, i . e . it is a claw clutch 11 . The protrusions 12 have been adapted to move between the limiters formed by the counterparts 13 and 14 located on the electric motors 3 and 4 in such a way that the small difference in rotational speed between the electric motors 3 and 4 allows the claw clutch 11 to rotate around the shaft 8 of the electric motor 4 from the first extreme position to the second extreme position or vice versa . Thanks to the rotational movement of the claw clutch 11 , the pitch angle of the propeller 1 can be precisely adjusted between two predefined pitch angles and the pitch angle can be kept precisely in this adjusted position . The resulting pitch angles can be selected e . g . for efficient forward drive and efficient reverse drive . When the claw clutch 11 has been driven to either one of its extreme positions due to a change in the rotation speed between the electric motors 3 and 4 , both electric motors 3 and 4 can participate in the rotation of the propeller 1 , thus obtaining the full output powers of both electric motors to rotate the propeller . With a claw clutch 11 between the electric motors 3 and 4 , the adjustment of the pitch angle can be over a wider range, the range being advantageously over 180 degrees . Without a claw clutch 11 , the adjustment range implemented with limiters is well below 180 degrees due to the physical limitations of the limiters . Thanks to such an adjustment of the pitch angle with a claw clutch 11 , the propeller 1 becomes efficient when moving forward or backward .Fig . 3 presents a second preferred embodiment of the claw clutch 11 arranged between the electric motors 3 and 4 . In this embodiment there are stepped protrusions 12 , i . e . claws , on the claw clutch that is between the electric motors 3 and 4 . In this embodiment , there are two steps 15 on each protrusion 12 of the claw clutch 11 , but the number of steps is not limited to two . Steppings 15 can also be made only on the one side of the claw / protrusion 12 of the claw clutch 11 , in which case the other extreme position of the claw clutch (= pitch angle) may be kept unchanged . Thanks to the stepping 15 , the adjustments based on the extreme positions occurring by means of the claw clutch 11 may be increased from two to more than two . This enables precise adjustment and optimization of the pitch angle of the propeller 1 for many different intended uses . The selection of the stepping 15 in use is done by moving the claw clutch 11 in the direction of the shafts 5 and 8 of the electric motors 3 and 4 in accordance with the arrow 16 in such a way that the protrusion 12 engages the counterpart 13 of the electric motor 3 at the point of the first step 15 or at the point of the second step . At the same time as the claw clutch 11 has been driven to its extreme position as shown in Fig . 3 , the counterpart 14 of the electric motor 4 is pressed against the second step 15 of the opposite protrusion 12 of the claw clutch . If there are a number of steps 15 , a number of adjustments can also be made as the claw clutch 11 moves from the first extreme position to the second extreme position around the shaft 8 by moving the claw clutch in the direction of the shaft of the electric motors to the desired step . With such steppings e . g . limited hydrogeneration efficiency is achieved at high speeds .With the embodiments described above, the pitch angle of the propeller can be adjusted to be optimal for different intended uses . Such intended uses are e . g . reversing or the production of electricity by hydrogeneration . With some of the embodiments , a steplessly optimized pitch angle of the propeller for different run speeds is obtained, which improves the efficiency ratio of the propeller . Adjustment of the pitch angle makes the propeller operate more quietly than a propeller without adjustment . A fixed-angle propeller generates noise from cavitation when the propeller is outside the designed operating range . Cavitation also mechanically wears the propeller blades , and so must be avoided .
[0024] Fig . 4 shows a situation ( from the direction of the shafts of electric motors ) wherein the propeller is in a sailing vessel in a so-called feathering position, in which case the propeller produces as little resistance as possible when rotating in the water . When entering feathering mode, the propeller typically remains oscillating around the minimum drag position for a short period of time . Over time the oscillation decreases and the propeller settles at the point of minimum resistance . This oscillation can be eliminated by adding an arrangement 40 to the propeller shaft for improving centering . Such an arrangement 40 comprises e . g . a wheel 41 disposed on the protrusion 12 of the claw clutch 11 , i . e . on the claw, which wheel is pressed by a spring 42 against the base of the counterpart 13 of the claw clutch . Correspondingly, the arrangement can be made using the second protrusion 12 of the claw clutch 11 and its counterpart 14 seen in Fig . 3 (not presented in Fig . 4 ) . The spring 42 presses the wheel 41 into the recess 43 at the base of the counterpart 13 of the claw clutch 11 ,in which case the oscillation quickly dampens . Conversely, the wheel 41 does not prevent the claw clutch 11 moving from the first extreme position to the second extreme position over the recess 43 . The properties of the spring 42 can be used to influence the settling of the claw clutch 11 into its feathering position .
[0025] With the solution according to the invention it is therefore possible to adjust the pitch angle of the blades 2 of a propeller 1 more than in solutions that are known in the art . For achieving a sufficiently good efficiency ratio in the recovery of kinetic energy, the pitch angles of the propeller blades 2 are adjusted in the solution according to the invention freely without constraints or within the permitted limits of the limiters 13 and 14 of the claw clutch 11 . The adjustment angles of the blades 2 are thus optimized with the solution according to the invention separately and, if necessary, for forward drive and reverse drive as well as for free sailing, in which case the propeller resistance is as small as possible, and finally for recovery of the kinetic energy of the sailing vessel , in which case the pitch angles of the blades 2 of the propeller 1 are adjusted in such a way that the efficiency ratio of kinetic energy recovery is as high as possible .
[0026] In this case the kinetic energy of the sailing vessel is recovered with the recovery arrangement according to the invention with an efficiency ratio whereby the amount of energy being charged into the accumulators of the sailing vessel during a sailing journey of normal duration is at least equal to, or greater than, the amount of electrical energy needed by the sailing vessel during a sailing journey of normal duration . The accumulators of the sailingvessel can thus be fully charged during a sailing journey of normal duration . In this way a sailing vessel can function also for long periods of time fully self-sufficiently when receiving the electrical energy it needs for recharging accumulators via the electric motor of the traction device when moving by means of the sails .
[0027] It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the examples described above, but that they may be varied within the scope of the claims presented below . Thus , for example, the adjustment mechanism for the pitch angle of a propeller can also be different to what is presented in the preceding . In this case, instead of a bevel gear transmission, there can be some other type of gear transmission mechanism or a completely other type of mechanism, which transfers the phase difference of the rotational movement of the shaft of the electric motors into an adjustment movement of the pitch angle of the propeller blades .
[0028] It is also further obvious to the person skilled in the art that the propeller can also, instead of the three blades presented, have two or more controllable blades , e . g . 4 , 5 , 6 or even more .
Claims
CLAIMS1 . An arrangement for adjust ing the pitch angle of a propel ler ( 1 ) in an electric propul s ion system, the system compri s ing two e lectric motors ( 3 , 4 ) , which motors are connected to a propel ler ( 1 ) that i s used for forward drive , reverse drive and al so , i f neces sary , as a generator for recharging accumulators , whereby the propel ler ( 1 ) compri ses a propel ler hub and at least two blades ( 2 ) fastened to the hub of the propel ler ( 1 ) , in which case the first shaft ( 5 ) of the f irst electric motor ( 3 ) i s hol low and it s end i s connected to the bl ades ( 2 ) of the propel ler ( 1 ) by means of the bevel gear ( 6 ) of the end of the f irst shaft ( 5 ) of the f irst electric motor ( 3 ) and the bevel gears ( 7 ) of the blades ( 2 ) of the propel ler ( 1 ) , characterized in that the electric motors ( 3 , 4 ) are situated concentrical ly one after the other , in which case the second shaft ( 8 ) of the second electric motor ( 4 ) pas ses through the hol low f irst shaft ( 5 ) of the f irst electric motor ( 3 ) and i s connected to the propel ler ( 1 ) for rotat ing the propel ler , and in that the arrangement al so compri ses motor control lers for driving and adjust ing the electric mot ors ( 3 , 4 ) as we l l as pos it ion sensors for monitoring the pos it ion rat io , i . e . the angular di f ference or phase di f ference , of the electric motors ( 3 , 4 ) .2 . Arrangement according to claim 1 , characterized in that the second shaft ( 8 ) of the second electric mot or ( 4 ) i s connected direct ly to the hub of the propel ler ( 1 ) for rotat ing the propel ler ( 1 ) .3 . Arrangement according to claim 1 , characterized in that the second shaft ( 8 ) of the second electric motor ( 4 )pas ses through the hub of the propel ler ( 1 ) and a bevel gear i s fastened to the end of it , which bevel gear i s connected to the bevel gears ( 7 ) of the blades of the propel ler ( 1 ) for rotat ing the propel ler ( 1 ) together with the f irst electric motor ( 3 ) .4 . Arrangement according to any of the preceding claims 1 -3 , characterized in that between the f irst electric motor ( 3 ) and the second electric motor ( 4 ) i s a clutch arrangement ( 30 ) .5 . Arrangement according to claim 4 , characterized in that the clutch arrangement ( 30 ) compri ses a claw clutch ( 11 ) compri s ing two protrus ions ( 12 ) in the direct ion of the second shaft ( 8 ) of the second e lectric motor ( 4 ) on both sides of the claw clutch ( 11 ) and a counterpart ( 13 , 14 ) to the claw clutch ( 11 ) on both elect ric motors ( 3 , 4 ) in such a way that the counterpart s ( 13 , 14 ) l imit the magnitude of the phase di f ference between the electric motors ( 3 , 4 ) when the claw clutch ( 11 ) moves around the second shaft ( 8 ) of the second electric motor ( 4 ) from the f irst extreme pos it ion to the second extreme pos it ion as the phase di f ference changes .6 . Arrangement according to claim 5 , characterized in that at least one of the protrus ions ( 12 ) of the cl aw clutch ( 11 ) has at least one step ( 15 ) in the direct ion of the second shaft ( 8 ) of the second e lectric motor ( 4 ) , and in that the claw clutch ( 11 ) i s movable in the direct ion of said shaft ( 8 ) for changing the step ( 15 ) to be engaged .7 . Arrangement according to any of the preceding claims 4 -6 , characterized in that on the protrus ion ( 12 ) of the clawclutch ( 11 ) i s a wheel ( 41 ) and a spring ( 42 ) , with which spring the wheel ( 41 ) i s pres sed against the reces s ( 43 ) of the counterpart ( 13 , 14 ) on the f irst or second electric motor ( 3 , 4 ) for stopping the osci l lat ion in the feathering pos it ion of the propel ler ( 1 ) .8 . Arrangement according to any of the preceding claims , characterized in that one or both of the electric motors ( 3 , 4 ) has a reduct ion gear .9 . Arrangement according to any of the preceding claims , characterized in that the electric motors ( 3 , 4 ) rotate at es sent ial ly the same speed of rotat ion .10 . Arrangement according to claim 8 , characterized in that the electric mot ors ( 3 , 4 ) rotate at es sent ial ly rotat ion speeds of es sent ial ly di f ferent magnitudes .11 . Arrangement according to any of the preceding claims , characterized in that the electric motors ( 3 , 4 ) have power output s of es sent ial ly the same magnitude .12 . Arrangement according to any of the preceding claims , characterized in that the electric motors ( 3 , 4 ) have power output s of es sent ial ly di f ferent magnitudes .