U.S. patent application number 17/591802 was filed with the patent office on 2022-08-11 for folding propeller for a water vehicle.
The applicant listed for this patent is Torqeedo GmbH. Invention is credited to Frank Despineux, Lars Glatzer.
Application Number | 20220250727 17/591802 |
Document ID | / |
Family ID | 1000006289861 |
Filed Date | 2022-08-11 |
United States Patent
Application |
20220250727 |
Kind Code |
A1 |
Despineux; Frank ; et
al. |
August 11, 2022 |
Folding Propeller for a Water Vehicle
Abstract
The present disclosure relates to a folding propeller (10) for a
water vehicle, comprising a hub (12) which is drivable about a
rotation axis (D) via a drive shaft, and a propeller blade (14)
which is arranged on the hub (12) to be pivotable about a pivot
axis (S) between a maximum closed position (P1) and a maximum open
position (P2), wherein the pivot axis (S) defines, together with a
normal (N.sub.D) to the rotation axis (D) which intersects the
pivot axis (S), a maximum opening plane (E.sub.Max), wherein in the
driven state and a pivot position of the propeller blade (14) in
the region of the maximum open position (P2), at least one opening
force acts upon the propeller blade (14) which results from
rotation of the folding propeller (10) and in relation to the
rotation axis (D) is directed substantially radially outwardly,
wherein an effective force application point (EAP) of the opening
force is arranged spaced from the maximum opening plane (E.sub.Max)
and is substantially arranged in the closing direction (SR) of the
propeller blade (14). The present disclosure further relates to a
folding propeller (10) comprising a propeller blade (14) which has
a reversal element (143) which is configured such that during
rearward drive a reversed thrust (F.sub.reverse) acts upon the
reversal element (143) and is directed substantially
perpendicularly to the propeller blade longitudinal axis (L.sub.P)
in the opening direction (OR) of the propeller blade (14).
Inventors: |
Despineux; Frank; (Wessling,
DE) ; Glatzer; Lars; (Rostock, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Torqeedo GmbH |
Gilching |
|
DE |
|
|
Family ID: |
1000006289861 |
Appl. No.: |
17/591802 |
Filed: |
February 3, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B63H 1/24 20130101 |
International
Class: |
B63H 1/24 20060101
B63H001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2021 |
DE |
10 2021 102 842.6 |
Claims
1. A folding propeller for a water vehicle, the folding propeller
comprising: a hub drivable about a rotation axis via a drive shaft,
and a propeller blade arranged on the hub to be pivotable about a
pivot axis between a maximum closed position and a maximum open
position, wherein the pivot axis defines, together with a normal to
the rotation axis which intersects the pivot axis, a maximum
opening plane, wherein in a driven state and a pivot position of
the propeller blade in a region of the maximum open position, an
opening force acts upon the propeller blade which results from
rotation of the folding propeller and in relation to the rotation
axis is directed substantially radially outwardly, wherein an
effective force application point of the opening force is arranged
spaced from the maximum opening plane and is substantially arranged
in a closing direction of the propeller blade.
2. The folding propeller according to claim 1, wherein the
effective force application point of the opening force corresponds
to a center of mass of the propeller blade, wherein one or both of
the opening force is a centrifugal force or the effective force
application point of the opening force corresponds to the center of
pressure of an uplift body arranged on the propeller blade, wherein
the opening force is an uplift force.
3. The folding propeller according to claim 1, wherein the folding
propeller has a stop apparatus which defines the maximum open
position of the propeller blade and the effective force application
point of the opening force is arranged outside the maximum opening
plane in the closing direction such that in the maximum open
position of the propeller blade, an opening moment acts which
presses the propeller blade against the stop apparatus.
4. The folding propeller according to claim 1, wherein the
propeller blade has an additional body that is one or both of
configured as an uplift body or configured as a mass body, wherein
the uplift body is configured as a winglet and the mass body has a
curved cylinder.
5. The folding propeller according to claim 1, wherein the
propeller blade has a first propeller blade portion that is
distally arranged, and a second propeller blade portion that is
proximally arranged, wherein the first propeller blade portion is
offset relative to the second propeller blade portion substantially
in the closing direction.
6. The folding propeller according to claim 1, wherein the
propeller blade has a propeller blade tip portion, a propeller
blade shaft portion and a propeller blade root portion, wherein the
propeller blade shaft portion is arranged between the propeller
blade tip portion and the propeller blade root portion, and wherein
one or both of the propeller blade shaft portion or the propeller
blade tip portion is offset relative to the propeller blade root
portion substantially in the closing direction of the propeller
blade.
7. The folding propeller according to claim 6, wherein the
propeller blade is configured such that a center of mass of the
propeller blade is arranged distally in relation to a centroid of
the propeller blade, wherein the center of mass of the propeller
blade is arranged either in the propeller blade tip portion or in
the propeller blade shaft portion.
8. The folding propeller according to claim 1, wherein the
propeller blade has a propeller root, wherein the propeller root
has a mounting apparatus for attaching the propeller blade to the
hub and the mounting apparatus defines the pivot axis.
9. The folding propeller according to claim 6, wherein the
propeller blade has an additional body that is configured as one or
more of an uplift body or as a mass body, wherein one or both of
the propeller blade tip portion or the additional body is formed of
metal.
10. The folding propeller according to claim 9, wherein the
propeller blade or the propeller blade tip portion is configured
integrally with the additional body.
11. The folding propeller according to claim 6, wherein one or both
of the propeller blade shaft portion or the hub is formed at least
partially of plastics.
12. The folding propeller according to claim 6, wherein the
propeller blade tip portion is one or both of connected
form-fittingly or frictionally to the propeller blade shaft
portion.
13. The folding propeller according to claim 6, wherein the
propeller blade tip portion has a tongue which is one or both of
cast into the propeller blade shaft portion or is connected to the
propeller blade shaft portion via a releasable connection, in
particular a screw connection.
14. The folding propeller according to claim 1, wherein a metal
insert is embedded in the propeller blade.
15. A folding propeller for a water vehicle, the folding propeller
comprising: a hub drivable about a rotation axis via a drive shaft,
and a propeller blade arranged on the hub to be pivotable about a
pivot axis, wherein the propeller blade has a reversal element,
which is configured such that during rearward drive, a reversed
force acts upon the reversal element and is directed substantially
perpendicularly to a propeller blade longitudinal axis in an
opening direction of the propeller blade.
16. The folding propeller according to claim 15, wherein the
reversal element is arranged in a propeller blade tip portion.
17. The folding propeller according to claim 15, wherein the
reversal element is arranged on the propeller blade to be pivotable
about the pivot axis which is substantially parallel to the
propeller blade longitudinal axis.
18. The folding propeller according to claim 15, wherein the
reversal element is pivotable between a maximum folded-in position
and a maximum folded-out position, wherein the reversal element
assumes a maximum folded-in position when the folding propeller is
in forward drive, wherein in the maximum folded-in position, the
reversal element is oriented substantially aligned with the
propeller blade, wherein the reversal element assumes the maximum
folded-out position when the folding propeller is in rearward
drive, wherein in the maximum folded-out position, the reversal
element experiences the reversed force.
19. The folding propeller according to claim 15, wherein the
reversed force generates an opening moment on the propeller blade
via a lever to the pivot axis.
20. A drive for a water vehicle having a folding propeller
comprising: a hub which is drivable about a rotation axis via a
drive shaft, and a propeller blade which is arranged on the hub to
be pivotable about a pivot axis between a maximum closed position
and a maximum open position, wherein the pivot axis defines,
together with a normal to the rotation axis which intersects the
pivot axis, a maximum opening plane, wherein in a driven state and
a pivot position of the propeller blade in a region of the maximum
open position, an opening force acts upon the propeller blade which
results from rotation of the folding propeller and in relation to
the rotation axis is directed substantially radially outwardly,
wherein an effective force application point of the opening force
is arranged spaced from the maximum opening plane and is
substantially arranged in a closing direction of the propeller
blade.
21. A drive for a water vehicle having a folding propeller
comprising: a hub drivable about a rotation axis via a drive shaft,
and a propeller blade arranged on the hub to be pivotable about a
pivot axis, wherein the propeller blade has a reversal element,
which is configured such that during rearward drive, a reversed
force-acts upon the reversal element and is directed substantially
perpendicularly to a propeller blade longitudinal axis in an
opening direction of the propeller blade.
Description
RELATED APPLICATION(S)
[0001] This application claims priority to and the benefit of
German Patent Application No. DE 10 2021 102 842.6, filed on Feb.
8, 2021, the contents of which is incorporated herein by reference
in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a folding propeller for a
water vehicle, in particular, for a sailing boat, and a drive for a
water vehicle with such a folding propeller.
BACKGROUND
[0003] Folding propellers for use in water vehicles, for example,
as a drive in sailing boats, are known. Boats can have a drive that
is equipped with a folding propeller in order, in certain
situations with an opened, driven folding propeller to generate a
desired forward propulsion, whereas in other situations, with a
closed non-driven folding propeller, these boats benefit from a
relatively low water resistance.
[0004] In the case of a folding propeller, the possibility exists
of opening and closing the propeller blades, particularly by means
of its design configuration: typically, two or more propeller
blades are mounted to be pivotable about respective pivot axes
arranged in a propeller hub and are thereby connected to said hub.
The propeller hub is driven by means of a drive shaft and the pivot
axes lie perpendicularly to the rotation axis of the propeller hub.
By means of this arrangement, during rotation of the propeller hub,
centrifugal forces act upon the propeller blades. These centrifugal
forces cause an opening of the propeller blades.
[0005] Typically, a folding propeller is configured as a pusher
propeller and is arranged in the central region or at the stern of
the boat.
[0006] In general, a driven propeller accelerates the surrounding
water against the direction of travel, so that its propeller blades
undergo a thrust in the direction of travel. This thrust in the
direction of travel is transmitted by the propeller blades to the
propeller hub and thus via the drive to the boat.
[0007] In the case of a folding propeller, such a thrust of the
accelerated surrounding water on the propeller blades during
forward travel supports the pivoting motion of the propeller blades
in the opening direction. During rearward travel, by contrast, such
a thrust acts closingly upon the propeller blades, i.e. it possibly
causes a pivot movement of the propeller blades in the closing
direction. In other words, during rearward travel, the propeller
blades accelerate the surrounding water substantially in the
direction of the bow of the boat, so that the resulting thrust is
applied to the propeller blades and is directed in a rearward
travel direction. This promotes a possible pivot movement of the
propeller blades in the closing direction, although the centrifugal
forces applied to the propeller blades counteract this closing
pivot movement. In practice it is observed that during rearward
travel, a middle open position of the propeller blades in which the
openingly acting centrifugal forces and the closingly acting
thrust-related forces substantially cancel each other out. The
resulting middle open position of the propeller blades leads to
significant losses in relation to forward propulsion and the
maneuverability of the boat.
[0008] For braking during forward travel, the disadvantages of
rearward travel described above apply correspondingly. A
complicating factor is the prevailing movement flow which
additionally presses the propeller blades in the closing
direction.
[0009] In order to counteract the problems described, for
conventional folding propellers, it is known in the case of
rearward travel to increase the centrifugal force by increasing the
rotary speed in order to open the propeller blades further from a
middle open position. With regard to the structural design, it is
known to increase the mass of the propeller blades of folding
propellers in order to increase the desired centrifugal force.
[0010] Propeller blades of folding propellers are typically made of
metal having high density values. Standard materials are, for
example, brass alloys or stainless cast steel with typical
densities of 7800 to 8900 kg/m.sup.3. The propeller blades are
typically made by casting and spur gear toothing responsible for
the synchronization of the propeller blades is made by machining.
With this material selection, the complete folding propeller
becomes very heavy and the forces arising during operation become
very large. This can, in turn, negatively affect the rest of the
drive system. For example, the heavy propeller blades can generate
unwanted vibrations and sounds. In addition, severe jolts can be
caused during opening of the propeller blades, due to the large
masses being moved. Furthermore, the production is complex and the
total weight of the boat is increased. It is also disadvantageous
that the alloys used either themselves corrode or have a corrosive
effect on other metal components of the boat. For this reason,
galvanic anodes which are to be regarded as expendable parts are
needed, so that the servicing costs increase.
SUMMARY
[0011] Proceeding from the known prior art, it is an object of the
present disclosure to provide an improved folding propeller for a
water vehicle, for example a boat, in particular a sailing
boat.
[0012] The object is achieved with a folding propeller having the
features of the independent claims. Advantageous developments are
disclosed in the subclaims, the description and the drawings.
[0013] Accordingly, a folding propeller for a water vehicle is
proposed which comprises a hub that is drivable about a rotation
axis by means of a drive shaft. The folding propeller also
comprises at least one propeller blade which is arranged on the hub
to be pivotable about a pivot axis between a maximum closed
position and a maximum open position. The pivot axis therein
defines, together with a normal to the rotation axis that
intersects the pivot axis, a maximum opening plane. If, in the
driven state, the propeller blade is in the maximum open position,
then an opening force acts upon the propeller blade, said force
resulting from the rotation of the folding propeller and being
directed substantially radially outwardly in relation to the
rotation axis. The folding propeller is configured in such a way
that an effective force application point of the opening force is
spaced from the maximum opening plane and is arranged substantially
in the closing direction of the propeller blade.
[0014] In other words, the effective force application point is
always arranged, relative to the bow of the boat, behind the
maximum opening plane, so that particularly in a pivot position of
the propeller blade in the region of the maximum open position, an
opening force can be constantly applied to the effective force
application point, said force generating via a lever to the pivot
axis, a moment acting with an opening effect on the propeller
blade.
[0015] An effective force application point should be understood in
the context of the present disclosure to be an imaginary or actual
application point or application region of a physical and/or
mechanical force that is suitable for representing the
corresponding force application and for making it usable for other
considerations. This is helpful, in particular, if for example a
local force variation (for example, in the case of uplift) or a
volume force (for example, in the case of centrifugal force) exists
and is to be used for defining a moment.
[0016] Furthermore, in the context of this disclosure, it is the
case that where reference is made to a propeller blade or a
propeller blade is described, this can apply to a plurality of, and
in particular all, propeller blades, which includes the folding
propeller. The folding propeller can comprise two, three, four or
more propeller blades.
[0017] The maximum closed position results when the propeller blade
is pivoted such that its longitudinal axis extends substantially
parallel to the rotation axis. Alternatively, this pivot position
can also be referred to as a folded-in position of the propeller
blade. This occurs, in particular, if the folding propeller is not
powered, that is, if the hub is not driven by the drive, for
example if the boat is operated in sail mode and accordingly a
water flow acts in the closing direction of the propeller
blade.
[0018] Accordingly, a pivot movement of the propeller blade about
the pivot axis toward the maximum closed position is herein
described as "closing" or "in the closing direction", whereas a
pivot movement directly contrary thereto is described as "opening"
or "in the opening direction". This applies accordingly for forces
and moments that can act upon the propeller blade.
[0019] The maximum open position results when the propeller blade
is pivoted so that, due to its arrangement in the folding
propeller, it can no longer carry out any further pivot movement in
the opening direction. Alternatively, this can be referred to as an
unfolded position of the propeller blade or the folding
propeller.
[0020] The paired terms open/closed position, open/close, maximum
open/closed position relate to the propeller blade but can relate
with equal validity to the entire folding propeller. This applies,
in particular, if the propeller blades arranged in the folding
propeller are pivot-synchronized, which can take place via a
synchronizing apparatus in the root region of the respective
propeller blades.
[0021] The effective force application point of the opening force
may correspond to the center of mass of the propeller blade. In
this case, the at least one opening force is a centrifugal
force.
[0022] Additionally, or alternatively, the effective force
application point of the opening force may correspond to the center
of pressure of an additional body arranged on the propeller blade.
This additional body can be configured as an uplift body generating
uplift, for example, in the form of a winglet generating an uplift.
In this case, the at least one opening force is an uplift
force.
[0023] The centrifugal force and the uplift force have in common
that they each are applied to an effective force application point
which is arranged on the propeller blade and is spaced in the
closing direction relative to the maximum opening plane, and that
they can generate, via a lever, an opening moment about the pivot
axis. This opening moment is suitable for pivoting the propeller
blade in the opening direction or for counteracting forces or
moments acting closingly on the propeller blade.
[0024] For this purpose, firstly the centrifugal force and later
the uplift force are considered below.
[0025] In the driven state, a centrifugal force acting upon the
center of mass can be applied to the propeller blade which can
essentially be dependent upon:
[0026] the current rotary speed, that is, the current angular speed
of the hub; and/or
[0027] the mass and mass distribution of the propeller blade, in
other words, the absolute value of mass and the position of the
center of mass within the propeller blade; and/or
[0028] the current relevant radius, in other words, the current
radial spacing of the center of mass of the propeller blade from
the rotation axis.
[0029] The propeller blade may have a center of mass which is
arranged such that in the maximum open position of the propeller
blade, it is spaced in the closing direction from an imaginary
maximum opening plane. In other words, the center of mass of the
propeller blade (referred to hereinafter simply as "center of
mass") in the maximum open position of the propeller blade has an
offset in the closing direction relative to the maximum opening
plane.
[0030] The maximum opening plane is imagined to be defined by the
pivot axis and that normal to the rotation axis which crosses the
pivot axis. Alternatively, the maximum opening plane can be
imagined as being the plane in which the pivot axis lies and the
normal of which is directed parallel to the rotation axis.
[0031] The offset of the center of mass as described above can have
the effect in the arrangement described that the centrifugal force
acting on the propeller blade due to the rotation of the folding
propeller which is applied, in a simplified consideration, to the
center of mass always has a centrifugal force component that is
directed perpendicularly to a lever about the pivot axis and thus
causes an opening moment. This applies, in particular, in the
maximum open position of the propeller blade.
[0032] In the arrangement of the center of mass, account can be
taken thereof that in the maximum closed position, it may also have
a further offset, specifically an offset in relation to the
rotation axis in the opening direction. In other words, in the
maximum closed position, the center of mass does not pass beyond
the rotation axis that is of decisive importance for the
centrifugal force. This further offset can ensure that with the
start of a rotary movement of the hub even from a standstill, an
opening centrifugal force can operate upon the propeller blade,
that is it can be applied over the current centrifugal force radius
to the center of mass and can act in the opening direction.
[0033] In one embodiment, the maximum open position may be defined
by means of a stop apparatus of the folding propeller. In other
words, in the maximum open position, a first element of the stop
apparatus, which may be arranged on the propeller blade, is in
contact with a second element of the stop apparatus, which may be
arranged on the hub. Thus, the stop apparatus can ensure that the
propeller blade can carry out no further pivot movement in the
opening direction, so that the center of mass can remain always
offset in the closing direction from the maximum opening plane.
Furthermore, the stop apparatus may comprise further means which
enables, for example, an adjustment thereof and/or by means of
which a damping may be set up. Damping elements can be used therein
to damp the impulse of the impact of the propeller blade against
the hub and/or to hold the propeller blade better in the maximum
open position in a possibly prevailing dynamic equilibrium.
[0034] In a further embodiment, the propeller blade may have a
first propeller blade portion and a second propeller blade portion,
wherein the first propeller blade portion is arranged distally and
the second propeller blade portion is arranged proximally in
relation to the pivot axis along the propeller blade longitudinal
axis. In other words, the first, distal propeller blade portion
along the propeller blade longitudinal axis has a greater spacing
from the rotation axis than the second, proximal propeller blade
portion.
[0035] In this regard, proximal herein characterizes a direction or
arrangement that faces or lies along the propeller blade
longitudinal axis substantially toward the pivot axis. Similarly
henceforth, distally characterizes a direction or arrangement that
faces or lies along the propeller blade longitudinal axis
substantially toward the propeller blade tip.
[0036] According to one embodiment, the first propeller portion may
be offset relative to the second propeller blade portion
substantially in the closing direction. This arrangement can enable
or favor the offset of the center of mass in the maximum open
position of the propeller blade relative to the maximum opening
plane in the closing direction and can positively influence it in
the context of the opening moment.
[0037] In a further embodiment, the propeller blade may have a
propeller blade tip portion, a propeller blade shaft portion and a
propeller root portion, wherein the propeller blade tip portion is
arranged distally, the propeller blade root portion is arranged
proximally and the propeller blade shaft portion is arranged
therebetween. The propeller blade shaft portion and/or the
propeller blade tip portion may be offset substantially in the
closing direction in relation to the propeller blade longitudinal
axis relative to the propeller blade root portion. In other words,
the propeller blade tip portion alone or the propeller blade tip
portion together with the propeller blade shaft portion may form
the first, distal propeller blade portion. Accordingly, the
propeller blade root portion alone or the propeller blade root
portion together with the propeller blade shaft portion may form
the second, proximal propeller blade portion.
[0038] According to a further embodiment, different propeller blade
portions may have different geometries and material densities. By
means of the arrangement of the different propeller blade portions
relative to one another, the arrangement of the center of
mass--and, in general, the effective force application points--can
thus be influenced to affect the opening moment.
[0039] In addition, such a multi-part embodiment of the propeller
blade is advantageous since different propeller blade
configurations can be produced by simple means in that, for
example, different embodiments of propeller blade tip portions and
propeller blade shaft portions can be assembled with regard to
significant parameters such as geometry, mass or material, in a
modular manner. Thus, by simple means, different propeller blades
can be produced with differently arranged centers of mass or
effective force application points for different folding
propellers.
[0040] Furthermore, the propeller blade may be designed such that
the center of mass is arranged distally in relation to the centroid
of the propeller blade and is located, for example, in the
propeller blade tip portion or in the propeller blade shaft
portion. In other words, the first, distal propeller blade portion
may have a greater material density than the second, proximal
propeller blade portion. In this way, a particularly advantageous
centrifugal force acting upon the propeller blade can be enabled,
in particular if this centrifugal force is considered in relation
to the mass of the propeller blade and thus to the inertia of the
folding propeller. This means that through the possibilities for
the arrangement of the center of mass, firstly the centrifugal
force behavior of the propeller blade can be optimized while,
simultaneously, secondly the mass and thus the inertia of the
propeller blade can be improved in the design configuration.
[0041] In some embodiments, the propeller blade may have a
propeller root, whereby the propeller root has a mounting apparatus
for attaching the propeller blade to the hub and the mounting
apparatus defines the pivot axis which in some embodiments extends
perpendicularly to the rotation axis.
[0042] In a further embodiment, the propeller blade tip portion can
be formed of metal. This enables an advantageous mass distribution
within the propeller blade and, in particular, the center of mass
can be influenced and the inertia of the propeller blade can be
optimized.
[0043] In a further embodiment, the propeller blade tip portion may
have an additional body which can form a propeller blade tip. The
additional body may be configured as an uplift body and/or as a
mass body. The uplift body is in some embodiments configured as a
winglet generating an uplift, whereas the mass body in some
embodiments has a mass element, for example, in the form of a
curved cylinder. The configuration of the additional body as a mass
body advantageously enables further influencing of the arrangement
of the center of mass. The advantages of an embodiment of the
additional body as an uplift body is described further below. In
addition, an advantageous embodiment of the additional body is
possible wherein the additional body is designed both as an uplift
body and also as a mass body and therefore has the respective
advantages together.
[0044] Therein, the propeller blade or the propeller blade tip
portion may be configured integrally with the additional body. This
can enable a stiff and/or flow-optimized attachment of the
additional body.
[0045] In a further embodiment, the propeller blade tip portion may
be connected form-fittingly or frictionally to the propeller blade
shaft portion. For example, the propeller blade tip portion may
have a tongue which may be cast into the propeller blade shaft
portion and/or is connected to the propeller blade shaft portion
via a releasable connection, in particular, a screw connection.
Alternatively, the propeller blade shaft portion may be connected
via a rivet connection or a bonded connection to the propeller
blade shaft portion.
[0046] This advantageously enables both a modular construction and
also a composite construction of the propeller blade, since the
components of the propeller blade portion can be formed differently
and can have different materials. In the case of a releasable
connection or a rivet connection, there are further advantages with
regard to repair, servicing or replacement of the propeller blade
tip portion.
[0047] In a further embodiment, a metal inlay may be embedded in
the propeller blade. Therein, the propeller blade or propeller
blade portions can be made of plastics. In some embodiments, the
metal inlay is molded in with a plastics injection molding method.
In other words, the propeller blade can be enclosed in plastics.
With a composite design of this type, the folding propeller can be
configured to be resistant to corrosion and at the same time, the
propeller blade can be improved with regard to the arrangement of
the center of mass with regard to the offset described above to
affect the opening moment and its inertia.
[0048] According to a further embodiment, the hub may be formed of
plastics. This reduces the moment of inertia of the hub and the hub
can be formed with a larger diameter. Thus, the spacing of the
mounting apparatus, and thus of the pivot axis, from the rotation
axis can be increased as compared with conventional folding
propellers. In this way, the radial spacing of the center of mass
from the rotation axis can be increased, which can have an
advantageous effect on the opening centrifugal force component. In
addition, said spacing increase enables more degrees of freedom for
the design of the propeller blade, in particular, with regard to
the additional body and/or the propeller blade tip portion. This
enables an improved geometrical integration within the folding
propeller arrangement, in particular, with regard to the maximum
closed position, where undesirable interference of the propeller
blades and, in particular, their propeller blade tip portions or
additional bodies shall not occur.
[0049] The uplift force, as mentioned elsewhere, which can act as
an opening force and can contribute to the creation of the opening
moment is considered below.
[0050] As described above, the uplift body may be configured in the
form of a winglet. In this regard, a winglet is to be understood as
an element which, due to its profile of, for example, an airfoil
profile and/or due to its arrangement, for example, an inclination,
pitch or torsion relative to the remainder of the propeller blade,
experiences a dynamic uplift when surrounding water flows over it.
This can be referred to as a "functional winglet".
[0051] In particular, the uplift force acting upon the uplift body
may include an openingly acting uplift force component, which acts
on the propeller blade to provide the opening moment. For
simplification and improved legibility of the description, the
winglet is primarily described below, although the description
equally applies, in general, for the uplift body according to the
present disclosure.
[0052] The openingly acting uplift force component acts upon the
center of pressure of the winglet and is oriented perpendicularly
to a lever which corresponds to the radial distance from the pivot
axis to the center of pressure of the winglet taking account of the
angle of action of the uplift force vector of the winglet. In the
context of this disclosure, the center of pressure is to be
understood to be the effective force application point of the
uplift force on the winglet. The position of the center of pressure
and the direction of the uplift force vector depends, inter alia,
on the profile and arrangement of the winglet. For example, the
center of pressure may be arranged at the intersection point of a
winglet uplift force vector and the winglet chord.
[0053] According to one embodiment, the winglet may be configured
so that in the driven state of the folding propeller, such an
openingly acting uplift force component engages upon the winglet in
each pivot position of the propeller blade, said force component
acting via a lever in the rotary direction of the opening moment.
In particular, this is the case when the propeller blade lies in
the maximum open position or in a position which lies in the region
of, or close to, the maximum open position.
[0054] According to one embodiment, the dynamic uplift force that
acts upon the winglet may be generated and/or favored in the
following way: The winglet may have a cross-section which
substantially corresponds to an airfoil which generates uplift when
a suitable medium flows round it. The flow required for the uplift
can take place through the relative movement of the winglet with
respect to the surrounding water. In particular, the aforementioned
flow can be caused by the rotation of the folding propeller, in
other words, by the circular movement of the winglet about the
rotation axis.
[0055] Therefore, in the driven state a dynamic uplift force can
act upon the winglet, said force being substantially dependent,
with regard to endogenous parameters, upon:
[0056] the rotary speed of the folding propeller, that is a current
velocity of travel of the winglet about the rotation axis;
and/or
[0057] a longitudinal inclination of the winglet, that is for
example, an inclination angle between the winglet longitudinal axis
and the propeller longitudinal axis or the longitudinal axis of the
second propeller blade portion; and/or
[0058] the winglet cross-section, for example, an airfoil profile
of the winglet, designated the winglet profile below; and/or
[0059] an angle of incidence between a winglet chord and that flow
against the winglet which is substantially directed tangentially to
the propeller blade periphery.
[0060] The winglet chord should be understood, similarly to an
airfoil chord, to be the imaginary connecting line between a
winglet front edge and a winglet rear edge. The winglet profile may
be configured so that the openingly acting uplift force component
is generated for both possible rotary directions of the folding
propeller. Accordingly, during forward drive, the winglet front
edge corresponds to a leading edge and during rearward drive, the
winglet rear edge corresponds to the leading edge.
[0061] A person skilled in the art will appreciate that in the
case, for example, of a required design trade-off, the embodiment
of the winglet profile in which a greater dynamic uplift is
generated during rearward travel than during forward travel (with
otherwise comparable parameters) can be advantageous. It can be
required, in particular, that the openingly acting uplift force
component during rearward travel advantageously contributes to the
opening moment since particularly during rearward drive, a closing
moment can act upon the propeller blade.
[0062] Furthermore, the winglet may be configured, for example, by
means of the winglet shape, the winglet inclination and/or the
attachment to the propeller blade such that in an opened position,
the movement flow of the surrounding water exerts an opening force
on the winglet.
[0063] In particular, a person skilled in the art will recognize
that the desired openingly acting uplift force component of the
winglet cannot be favorably influenced exclusively by means of one
of the embodiments described above. For example, the winglet must
not necessarily have an airfoil profile, but rather may also be
formed, for example, via obliquely positioned plate elements which
may have a planar, curved or other suitable shape.
[0064] Furthermore, advantageous embodiments may be included in
which the propeller blade portions are arranged adjustable among
one another or in which the additional body is arranged adjustable
relative to a propeller blade portion. In such configurations, the
opening moment can be adapted by optimizing the corresponding
centrifugal force and/or the uplift force and, in particular, with
respect to different operating parameters such as, for example,
rotary speed, propeller blade pivot position, surrounding water
flow. This optimization applies, in particular, with regard to the
respectively resultant closing moment, which a person skilled in
the art can ascertain during the designing of the folding propeller
for different operating scenarios and parameters.
[0065] In some embodiments, the propeller blade has on an end side
of the propeller blade root portion or the propeller blade root, a
spur gear toothing, by means of which the propeller blade can mesh
with other propeller blades of the folding propeller in order to
synchronize the pivot movement of the propeller blades with one
another. Therein the propeller blades may be arranged at even
angular spacings surrounding the hub.
[0066] The object defined above is further achieved by means of a
folding propeller having the features of independent claim 15.
Advantageous developments are disclosed in the subclaims, the
following description and the drawings.
[0067] Features of the folding propeller according to claim 15 can
be used, in particular, in combination and/or additionally with the
embodiments described above. Such combinations and/or additions can
therefore be regarded as being disclosed.
[0068] Accordingly, a folding propeller for a water vehicle is
proposed which comprises a hub that is drivable about a rotation
axis by means of a drive shaft. The folding propeller also
comprises a propeller blade which is arranged on the hub to be
pivotable about a pivot axis. The propeller blade has a reversal
element which is configured such that during rearward drive, a
reversed force acts upon the reversal element which is oriented
substantially perpendicularly to the propeller blade longitude axis
in the opening direction of the propeller blade.
[0069] The attribute "reversed" in the expression "reversed force"
denotes, in the context of the present disclosure, a direction
which can be directed substantially contrary to the propeller blade
uplift force primarily striven for to generate a resulting drive
thrust. According to one embodiment, the reversal element is
arranged in a propeller blade tip portion. This enables the
advantageous elongation of a desired lever for the reversed force.
This is relevant, in particular, with regard to an observation of
moments acting openingly or closingly on the propeller blade during
rearward drive.
[0070] According to a further embodiment, the reversal element is
arranged on the propeller blade pivotable about a pivot axis which
is substantially parallel to the propeller longitudinal axis. This
can take place by means of a corresponding mounting apparatus.
[0071] In a development, the reversal element may be arranged on
the propeller blade pivotable between a maximum folded-in position
and a maximum folded-out position. The reversal element assumes the
maximum folded-in position when the folding propeller is in forward
drive. This can take place substantially automatically through the
flow present during forward drive. Therein, the reversal element
can be oriented, in the maximum folded-in position, substantially
aligned with the propeller blade. This minimizes or reduces
undesirable flow resistance in forward drive.
[0072] Furthermore, in this development, the reversal element
assumes the maximum folded-out position when the folding propeller
is in rearward drive. The reversal element may, in particular, be
configured and arranged on the propeller blade so that the pivoting
of the reversal element takes place in the direction of the maximum
folded-out position substantially automatically due to the flow
against the propeller blade edge accordingly present during
rearward drive. The maximum folded-out position may be defined by
design means or a suitable arrangement. For example, suitable stop
elements may be arranged on the reversal element and/or on the
propeller blade. In other words, the stop elements are configured
to prevent the reversal element being pivoted beyond the maximum
folded-out position. Furthermore, the stop elements and/or the
mounting apparatus may be configured to transfer the flow forces
acting upon the reversal element in rearward drive as reversed
force from the reversal element to the propeller blade.
[0073] Furthermore, the reversed force can generate an openingly
acting moment on the propeller blade via a lever to the pivot axis
of the propeller blade.
[0074] Naturally, in the case of folding propellers during rearward
drive, forces or moments acting openingly and closingly upon the
propeller blade act against one another. Accordingly, the reversal
element may be configured and connected to the propeller blade such
that during rearward drive, the flow forces of the flow can be
converted at the reversal element into the reversed force which
engages upon an effective force application point and via the lever
to the pivot axis of the propeller blade, generates an opening
moment. In particular, this opening moment is suitable for
preventing a pivot movement of the propeller blade in the closing
direction or for holding the propeller blade in a region between a
middle open position and a maximum open position.
[0075] Further advantages and features of the present disclosure
are disclosed in the description below of exemplary embodiments.
The features described therein can be implemented alone or in
combination with one or more of the aforementioned features,
provided the features do not contradict one another. The following
description of preferred exemplary embodiments makes reference to
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0076] Exemplary embodiments of the present disclosure are
explained in detail below with the following description of the
drawings. In the drawings:
[0077] FIG. 1 is a schematic partially sectional plan view of a
folding propeller according to one embodiment;
[0078] FIG. 2a is a partially sectional plan view of a propeller
blade of the folding propeller shown in FIG. 1 in a maximum closed
position and in a middle open position;
[0079] FIG. 2b is a continuation of the view of FIG. 2a;
[0080] FIG. 3a is a schematic front view of a folding propeller
according to a further embodiment;
[0081] FIG. 3b is a schematic side view of a propeller blade tip
portion of a propeller blade;
[0082] FIG. 3c is a schematic side view of a propeller blade tip
portion of a propeller blade;
[0083] FIG. 3d is a schematic front view of a tongue of a propeller
blade tip portion of the propeller blade shown in FIG. 3a according
to one embodiment;
[0084] FIG. 3e is a schematic front view of a tongue of a propeller
blade tip portion of the propeller blade shown in FIG. 3a according
to a further embodiment;
[0085] FIG. 4 is a schematic front view of a folding propeller with
a propeller blade having a metal inlay according to a further
embodiment;
[0086] FIG. 5 is a schematic partially sectional plan view of a
folding propeller with a winglet according to a further
embodiment;
[0087] FIG. 6 is a schematic cross-sectional view of an embodiment
of the winglet shown in FIG. 5;
[0088] FIG. 7 is a perspective view of an embodiment of the winglet
shown in FIG. 5;
[0089] FIG. 8 is a perspective schematic view of a water vehicle
during rearward drive with a folding propeller according to a
further embodiment;
[0090] FIG. 9a is a schematic front view of the propeller blade
shown in FIG. 8;
[0091] FIG. 9b is a schematic side view of the propeller blade
shown in FIG. 9a;
[0092] FIG. 10a is a schematic front view of the propeller blade
shown in FIG. 8 during forward drive; and
[0093] FIG. 10b is a schematic side view of the propeller blade
shown in FIG. 10a during forward drive.
DETAILED DESCRIPTION
[0094] Exemplary embodiments are described below making reference
to the drawings. Herein, identical, similar or similarly acting
elements are provided with the same reference signs in the
different drawings, and repeated description of these elements is
in part dispensed with for the avoidance of redundancy.
[0095] FIG. 1 shows a schematic partially sectional plan view of a
folding propeller 10 according to a first embodiment. The folding
propeller 10 comprises a hub 12 and two identical propeller blades
14.
[0096] In the text below, the present embodiments are illustrated
for simplification on the basis of an individual propeller blade
14. For greater clarity, the reference signs in FIG. 1 are shown
distributed over both propeller blades 14, although the two
propeller blades 14 do not differ functionally or structurally.
[0097] The propeller blade 14 has a propeller root 15 which has a
mounting apparatus 16 for attaching the propeller blade 14 to the
hub 12. The hub 12 is rotatable about a rotation axis D and
drivable via a boat drive shaft (not shown) to which it is
connected for conjoint rotation. The mounting apparatus 16 defines
a pivot axis S which is arranged perpendicularly to the rotation
axis D. The propeller blade 14 is pivotable about the pivot axis S
between a maximum closed position (P1, not shown) and a maximum
open position P2. In the contact region of the propeller root 15
and the hub 12, the folding propeller 10 has a stop apparatus 18
which limits the opening of the propeller blade 14 and thus defines
the maximum open position P2.
[0098] A normal N.sub.D to the rotation axis D crossing the pivot
axis S defines, together with the rotation axis D, a maximum
opening plane E.sub.Max of the propeller blade 14 or of the folding
propeller 10. The maximum opening plane E.sub.Max can arbitrarily
but does not necessarily correspond to the maximum open position
P2, since the latter is defined by the stop apparatus 18, whereas
the maximum opening plane E.sub.Max substantially depends upon the
pivot axis. Rather, the maximum opening plane E.sub.Max serves to
define the arrangement of effective force application points, for
example, the center of mass MSP of the propeller blade 14. The
center of mass MSP is spaced from the maximum opening plane
E.sub.Max and is substantially arranged and/or displaced in the
closing direction SR of the propeller blade 14. The opening
direction OR and the closing direction SR correspond substantially
to arc-shaped pivot movements of the propeller blade 14 when it is
pivoted about the pivot axis S. The stop apparatus 18 is configured
so that the center of mass MSP in the maximum open position P2 is
spaced, in the closing direction SR, from the maximum opening plane
E.sub.Max.
[0099] The propeller blade 14 has a first, distally arranged
propeller blade portion 14a and a second, proximally arranged
propeller blade portion 14b wherein the first propeller blade
portion 14a is offset relative to the second propeller blade
portion 14b substantially in the closing direction SR.
[0100] Accordingly, an advantageous spacing of the center of mass
MSP in the closing direction SR in relation to the maximum opening
plane E.sub.Max is achieved or increased. The center of mass MSP
represents an effective force application point EAP of a
centrifugal force that is suitable for generating an opening moment
(see FIG. 2a, b).
[0101] Furthermore, the propeller blade 14 has a propeller blade
tip portion 144, a propeller blade shaft portion 146 and a
propeller blade root portion 148. In the embodiment shown in FIG.
1, the propeller blade tip portion 144 is connected to the
propeller blade shaft portion 146 form-fittingly and frictionally
and together they form the first propeller blade portion 14a,
whereas the propeller blade root portion 148 forms the second
propeller blade portion 14b. The first and second propeller blade
portions 14a and 14b are firmly connected to one another so that a
transmission of the propeller thrust forces is assured.
[0102] The propeller blade tip portion 144 has an additional body
142 which forms a propeller blade tip 19. In the present example,
the additional body 142 is formed integrally with the propeller
blade tip portion 144. The additional body 142 can be present in
the form of an uplift body 142a, for example, in the form of a
winglet 13 (see FIG. 5). The uplift body 142a can be configured
such that, when the folding propeller 10 is driven, it experiences
a dynamic uplift which is applied to the center of pressure DP of
the uplift body 142a. The center of pressure DP thus represents an
effective force application point EAP of the dynamic uplift that is
suitable for generating an opening moment (see FIG. 5).
[0103] In the embodiment shown, due to the offset described above
of the first propeller blade portion 14a relative to the second
propeller blade portion 14b in the closing direction SR, an
advantageous spacing of the center of pressure DP in the closing
direction SR relative to the maximum opening plane E.sub.Max is
also achieved or increased.
[0104] In the regions in which different propeller roots 15 can
make contact with one another or can overlap one another, the
propeller roots 15 of the two propeller blades 14 have spur gear
toothing (not shown). This enables an interlocking of the propeller
blades 14 and thus a synchronization of the pivot movements of the
propeller blades 14.
[0105] Furthermore, in the embodiment shown, the propeller blade 14
is configured such that the center of mass MSP is arranged distally
in relation to the centroid VSP of the propeller blade 14. In other
words, the material density in the distal region of the propeller
blade 14 is greater than in the proximal region. This is achieved,
for example, in that the additional body 142 is present in the form
of a mass body 142b (see FIGS. 3a and 3c). For example, the mass
body 142b and/or the propeller blade tip portion 144 may thus be
formed of metal. In general, the additional body 142 and/or the
propeller blade tip portion 144 can be made of a material of higher
density than the remainder of the propeller blade portions (for
example, the propeller blade shaft portion 146 and propeller blade
root portion 148). In the embodiment shown, the propeller blade
shaft portion 146 consists of plastics.
[0106] The embodiment described above has the advantage that the
folding propeller can be configured particularly weight-optimized,
whereas the desired centrifugal force can be influenced by an
arrangement of the center of mass as far distally as possible.
[0107] Additionally, the hub 12 is formed of plastics. This reduces
the moment of inertia of the hub 12 and the hub 12 can be
constructed with a larger diameter. By this means, the pivot axis S
defined by the mounting apparatus 16 can be arranged with a greater
spacing h (see FIG. 2) from the rotation axis D. This has the
result that, in an opened pivot position of the propeller blade 14,
the center of mass MSP and the center of pressure DP have a greater
spacing from the rotation axis D, which in turn leads to an
increase in the desired opening forces.
[0108] In the description of the following drawings, the relevant
forces and moments will be considered, inter alia.
[0109] FIG. 2a shows a schematic plan view of the folding propeller
10 of FIG. 1, wherein a single propeller blade 14 is shown in two
different pivot positions, specifically the maximum closed position
P1 and a middle open position Pm. Starting from the maximum closed
position P1, due to the rotation of the hub 12 about its rotation
axis D, a centrifugal force F.sub.centrifugal,1 acts upon the
center of mass MSP which is spaced at a distance
r.sub.centrifugal,1 (not shown) from the rotation axis D, wherein
the centrifugal force F.sub.centrifugal,1 is directed radially
outwardly, i.e. in the direction of a normal (not shown) extending
through the center of mass MSP to the rotation axis D. The
centrifugal force F.sub.centrifugal,1 has an opening force
component F.sub.centrifugal,lever,1 which is applied to the center
of mass MSP and is directed perpendicularly to a lever with the
length of the spacing a.sub.MSP-S from the center of mass MSP to
the pivot axis S. The opening force component
F.sub.centrifugal,lever,1 thus generates, via said lever, an
opening moment M.sub.opening,1 (not shown). By this means, the
center of mass MSP, disregarding the translational travel motion of
the boat, is accelerated tangentially relative to the pivot axis S
and is thus pivoted out of the maximum closed position P1.
[0110] The relationship just described applies for both possible
rotations DR of the hub 12, that is, for forward travel and
rearward travel of the boat.
[0111] As a result, the propeller blade 14 pivots in the opening
direction OR, wherein the representation of the middle open
position Pm in FIG. 2a makes clear that with increasing spacing
r.sub.centrifugal,m of the center of mass MSP from the rotation
axis D, the centrifugal force F.sub.centrifugal,m has also
increased in relation to F.sub.centrifugal,1. F.sub.centrifugal,m
can be determined as follows:
F.sub.centrifugal,m=m*.omega..sup.2*r.sub.centrifugal,m,
[0112] where m=mass of the propeller blade 14, .omega.=angular
velocity of the hub rotation and
r.sub.centrifugal,m=pivot axis spacing
h+a.sub.MSP-S*cos(.alpha..sub.m);
wherein h=spacing of pivot axis S from rotation axis D, and
.alpha..sub.m=opening angle in the middle pivot position.
[0113] In general, the opening angle .alpha. represents the angle
between the maximum opening plane E.sub.Max and the lever, i.e. the
distance from the center of mass MSP to the pivot axis S.
[0114] FIG. 2b shows a continuation of the pivot movement of FIG.
2a, wherein the propeller blade 14 is pivoted into the maximum open
position P2.
[0115] In particular, in this maximum open position P2, an opening
force component F.sub.centrifugal,lever,2 acts upon the center of
mass MSP and generates an opening moment M.sub.opening,2 as
described above. Therein, M.sub.opening,2 and
F.sub.centrifugal,lever,2 can be determined as follows:
M.sub.opening,2=F.sub.centrifugal,lever1,2*a.sub.MSP-S
where
F.sub.centrifugal,lever,2=F.sub.centrifugal,2*sin(.alpha..sub.2)
[0116] The opening force F.sub.centrifugal,lever,2 thereby presses
the propeller blade 14 against the stop apparatus 18. In addition,
the opening moment M.sub.opening is greater than a closing moment
M.sub.close (not shown) acting overall simultaneously. This
applies, in particular, for the rearward drive and the braking.
[0117] FIG. 3a shows a schematic front view of a folding propeller
blade 14 of a folding propeller 10 according to a further
embodiment. The additional body 142 can be configured as a mass
body 142b, for example, as a cylinder (see FIG. 3c), in some
embodiments as a curved cylinder or as an uplift body 142a (see
FIG. 3b) or in another suitable form. The propeller blade tip
portion 144 is therein in some embodiments formed integrally with
the additional body 142. Furthermore, the propeller blade tip
portion 144 may be formed of metal.
[0118] In some embodiments, the propeller blade tip portion 144 is
connected form-fittingly or frictionally to the propeller blade
shaft portion 146. As shown dashed in FIG. 3a, the propeller blade
tip portion 144 has a tongue 1440 which is cast into the propeller
blade shaft portion 146 and/or is connected to the propeller blade
shaft portion 146 via a screw connection or a rivet connection or
another suitable connection. Furthermore, the propeller blade shaft
portion 146 is in some embodiments formed of plastics.
[0119] The tongue 1440 is in some embodiments formed integrally
with the propeller blade tip portion 144. The tongue 1440 can be
configured such that the propeller blade tip portion 144 has a
stepped form from a separation edge 145 in the proximal direction
(see FIG. 3b, 3c), in order to be received in a corresponding
distally oriented recess in the propeller blade shaft portion
146.
[0120] In order to configure the possible connection interfaces of
additional bodies 142 to the propeller blade 14 or from the
propeller blade tip portion 144 to the propeller blade shaft
portion 146, a person skilled in the art would accordingly take
account of the radii R1 and R2 shown in FIG. 3a.
[0121] FIGS. 3b and 3c show, in a schematic side view, a further
embodiment of the propeller blade tip portion 144. It has an
additional body 142 which in FIG. 3b is present in the form of a
uplift body 142a and is inclined in the rearward travel direction.
Such an inclination of the uplift body 142a can be used to generate
dynamic uplift (see FIG. 5). In FIG. 3c, the additional body 142 is
present as a mass body 142b, in this case in the form of a curved
cylinder with the curvature of radius R2 (see FIG. 3a). The mass
body 142b can be used for increasing the centrifugal force. The
tongue 1440 serves for the aforementioned connection of the
propeller blade tip portion 144 to the propeller blade shaft
portion 146.
[0122] The separation edge 145 can be used for the design or for
improving the connection of the aforementioned propeller blade
portions.
[0123] FIG. 3d, 3e show schematic frontal views and cross-sections
of the tongue 1440 of the propeller blade tip portion 144 which
serves for the form-fitting and/or frictional connection to the
propeller blade shaft portion 146. In FIG. 3d, the tongue 1440 has
bores 1442 which can serve in the aforementioned connection, for
example, as through holes or threaded holes for a screw connection,
bolt connection or rivet connection. In FIG. 3e, by contrast, the
tongue 1440 has webs 1444 which can advantageously be used in the
aforementioned connection, for example, for the aforementioned
injection molding or casting connection.
[0124] As shown in FIGS. 3a, 3d and 3e, the tongue 1440 can be
trapezoid or rectangular, but can also have any other shape
suitable for the connection described.
[0125] FIG. 4 shows a schematic front view of a plastics propeller
blade 14 with a metal inlay 20 according to a further embodiment of
the folding propeller 10. Herein, the metal inlay 20 is embedded in
the plastics propeller blade 14. For example, the metal inlay 20
can be cast into the plastics propeller blade 14. In this way,
advantages are achieved with regard to corrosion and servicing,
while due to the metal inlay 20, the arrangement of the center of
mass MSP and a sufficient stiffness of the plastics propeller blade
14 can be ensured. The embodiment shown in FIG. 4 can have, in
particular, the previously and subsequently described features, for
example, an additional body 142, even if this is not explicitly
shown in FIG. 4.
[0126] FIG. 5 shows a schematic plan view of a further embodiment
of a propeller blade 14 of the folding propeller 10 in the maximum
closed position P2. In this example, the propeller blade 14 has an
uplift body 142a in the form of a winglet 13. The winglet 13 has,
in its cross-section (see FIG. 6), an airfoil profile with a
correspondingly formed winglet upper side 13a and winglet underside
13b. Furthermore, the winglet 13 has a first, distal portion 131
and a second, proximal portion 132 wherein the latter is suitably
equipped, in particular, for connecting to the remainder of the
propeller blade 14. The winglet longitudinal axis L.sub.W is
inclined relative to the remainder of the propeller blade 14 in the
closing direction SR, in particular, inclined by the angle .beta.
relative to the longitudinal axis L.sub.shaft of the propeller
blade shaft portion 146. The winglet 13 is configured (see FIG. 6)
such that, in particular, when surrounding water flows over the
winglet 13, a dynamic uplift force F.sub.uplift acts upon the
winglet and, associated therewith, an openingly acting uplift force
component F.sub.uplift,lever acts upon the propeller blade 14.
F.sub.uplift,lever is the component of the uplift force
F.sub.uplift which generates an opening moment M.sub.uplift,opening
that acts perpendicularly via a lever to the pivot axis on the
propeller blade 14.
[0127] Shown schematically in FIG. 5 is an effective application
point EAP of the uplift force F.sub.uplift acting overall upon the
winglet 13 in the form of a projection of the center of pressure DP
of the winglet profile. Accordingly, the relevant lever results
from the spacing of the center of pressure DP from the pivot axis
S, that is the distance app-s. In the design of the folding
propeller 10, a person skilled in the art can thus easily create a
model to describe the moment M.sub.uplift,opening which acts
openingly due to the uplift and which comprises the parameters
shown in FIG. 5. A person skilled in the art can thus determine,
for a given configuration, an advantageous winglet inclination
angle .beta.. The winglet 13 is configured such that the effective
force application point EAP of the uplift force F.sub.uplift is
clearly spaced from the maximum opening plane E.sub.Max and is
offset in the closing direction SR.
[0128] The arrangement shown in FIG. 5 of the winglet 13 in
relation to the propeller blade shaft portion 146 is geometrically
simple and here is substantially described by means of the two
longitudinal axes L.sub.W and L.sub.shaft and their inclination
angle .beta. to one another. However, the winglet arrangement can
deviate therefrom substantially. Alternatively, the winglet 13 can
be configured elliptical or annular, for example, as a spiroid or a
split-wing loop. Furthermore, the winglet 13 can have a plurality
of portions and therefore a plurality of portion longitudinal axes
(for example, a T-shape or a Y-shape) and can accordingly be
arranged on the propeller blade shaft portion 146 or on the
propeller blade 14.
[0129] FIG. 6 shows schematically an exemplary profile in a section
A-A of the winglet 13 of FIG. 5. In some embodiments, the winglet
profile is configured as a normal profile, wherein the winglet
upper side 13a is configured convex and the winglet underside 13b
is configured s-shaped. If a normal profile is used, this can in
some embodiments be oriented toward the folding propeller 10 such
that during rearward drive, the flow of the surrounding water,
represented here as the flow AS, and thus the dynamic uplift, is
particularly advantageously used. A reinforcement of the opening
moment M.sub.opening is particularly preferred for rearward drive.
Alternatively, the winglet profile can be configured as a
symmetrical profile or can have any further advantageous,
uplift-generating profile shape. As shown by way of example in FIG.
6, the surrounding water flows faster on the upper side 13a than on
the underside 13b, so that the dynamic uplift force F.sub.uplift
acts upon the winglet 13, is applied to the center of pressure DP
or the effective force application point EAP and is directed
perpendicularly to the flow AS and away from the winglet upper side
13a.
[0130] FIG. 7 shows a schematic perspective view of the winglet 13
according to one embodiment. In this example, the winglet 13 is
formed integrally. In this way, by simple design means, a
hydrodynamically optimized propeller blade can be provided.
[0131] FIG. 8 shows a perspective schematic view of a water vehicle
100 during rearward drive with a folding propeller 10 according to
a further embodiment. The folding propeller 10 comprises a hub 12
and two identical propeller blades 14. The propeller blade 14 is
attached in the region of its propeller root (not shown) via a
mounting apparatus (not shown) to the hub 12. The hub 12 is
rotatable about a rotation axis D and is drivable via a boat drive
shaft (not shown) to which it is connected for conjoint rotation.
The mounting apparatus (not shown) defines a propeller blade pivot
axis S which is arranged perpendicularly to the rotation axis D.
The propeller blade 14 is pivotable about the propeller blade pivot
axis S between a maximum closed position (not shown) and a maximum
open position P2. In a contact region of the propeller root (not
shown) and the hub 12, the folding propeller 10 has a propeller
blade stop apparatus (not shown) which limits the opening of the
propeller blade 14 and thus defines the maximum open position
P2.
[0132] The propeller blade 14 is configured as an airfoil which
means that, on rotation of the hub 12 in the rotation direction DR
or contrary to the rotation direction DR, it undergoes uplift
forces through the displacement of the surrounding water and
transmits said forces in the form of a resultant thrust via the hub
12 to the drive.
[0133] In the propeller blade tip portion 144, a reversal element
143 is arranged to be pivotable about a reversal element pivot axis
S.sub.U which is substantially parallel to the propeller blade
longitudinal axis L.sub.P. The propeller blade 14 has a front edge
150 and a rear edge 151.
[0134] In FIG. 8, the hub 12 is rotated in the rotation direction
DR which corresponds to a rearward drive, so that due to the linear
velocity v.sub.linear, a flow AS impacts upon the propeller blade
rear edge 151. The flow AS presses against the reversal element
143, which pivots or is pivoted accordingly in the direction of the
maximum folded-out position U2. The stream AS henceforth impinging
upon the reversal element 143 brings about the reversed force
F.sub.reverse which acts via an effective force application point
EAP on the propeller blade 14 and via a lever of length a.sub.U-S
to the propeller blade pivot axis S, generates an opening moment
M.sub.opening,reverse.
[0135] By means of the rotation of the hub 12 in the rotation
direction DR, the propeller blade 14 experiences uplift forces
F.sub.uplift,rearward directed in the rearward direction of travel,
the sum of which results in a thrust F.sub.thrust,rearward directed
in the rearward direction of travel. In addition, the uplift forces
F.sub.uplift,rearward cause a moment (not shown) having a closing
effect on the propeller blade 14, the lever of which is
significantly smaller, substantially half as great as the lever
a.sub.U-S of the previously described openingly acting moment
M.sub.opening,reverse.
[0136] In the design of the folding propeller 10, on the basis of
the arrangement disclosed, a person skilled in the art can thus
easily create a model to quantify the openingly and closingly
acting moments, comprising the elements and parameters shown in
FIG. 8. A skilled person can therefore, for example, configure the
propeller blade 14 and the reversal element 143 such that a desired
opening moment for particular parameter configurations results.
[0137] FIG. 9a shows a schematic front view and FIG. 9b the
corresponding side view of the propeller blade 14 shown in FIG. 8
during rearward drive of the folding propeller 10. In the example
shown, the reversal element 143 is arranged in the propeller blade
tip region, that is, at the distal end of the propeller blade 14.
Through the rotation of the propeller blade 14, the reversal
element 143 moves with the linear velocity about the rotation axis.
Thereby, a flow AS lies continuously against the reversal element
143. Thereby, an uplift results which generates the reversed force
F.sub.reverse which acts upon the reversal element 143 and pivots
the reversal element 143 about its pivot axis S.sub.U into its
maximum folded-out position U2. This pivoting is limited by a stop
apparatus (not shown) which therefore defines the maximum
folded-out position U2. Furthermore, a transmission apparatus (not
shown) is provided on the propeller blade 14 in the region of the
reversal element 143, which is configured to transmit the reversed
force F.sub.reverse engaging upon the reversal element 143 to the
propeller blade 14, so that F.sub.reverse--as described in relation
to FIG. 8--generates via the lever a.sub.U-S to the propeller blade
pivot axis S, the opening moment M.sub.opening,reverse. The stop
apparatus can therein be configured integrally with the
transmission apparatus. In particular, the transmission apparatus
can be configured to transmit the reversed force F.sub.reverse
applied to the reversal element 143 via suitable elements to the
propeller blade 14 by means of compression forces and/or tensile
forces.
[0138] As FIG. 9b shows, the reversal element 143 can have a form
in its distal end region which is suitable to catch the flow AS
during rearward drive such that the reversal element 143 is pivoted
out of a maximum folded-in position (see FIG. 10a, b) automatically
or autonomously in the direction of its maximum folded-out position
143.
[0139] FIG. 10a shows a schematic front view and FIG. 10b the
corresponding side view of the propeller blade 14 shown in FIG. 8
during forward drive of the folding propeller 10. Due to the flow
AS against the propeller blade front edge 150, the reversal element
143 remains substantially in its maximum folded-in position U1. If
braking is carried out during forward travel, the vector of the
linear velocity V.sub.linear,forward rotates accordingly into the
opposite direction and consequently also the flow AS. By this
means, the reversal element 143 is pivoted into the maximum
folded-out position U2, so that, as described above, the reversal
element 143 can provide a moment acting closingly on the propeller
blade 14.
[0140] As far as practicable, all the individual features which are
described in the exemplary embodiments can be combined with one
another and/or exchanged without departing from the scope of the
present disclosure.
REFERENCE SIGNS
[0141] 10 Folding propeller [0142] 12 Hub [0143] 13 Winglet [0144]
13a Winglet upper side [0145] 13b Winglet underside [0146] 14
Propeller blade [0147] 14a First, distal propeller blade portion
[0148] 14b Second, proximal propeller blade portion [0149] 15
Propeller root [0150] 16 Mounting apparatus [0151] 18 Stop
apparatus [0152] 19 Propeller blade tip [0153] 20 Metal inlay
[0154] 100 Water vehicle [0155] 131 First, distal winglet portion
[0156] 132 Second, proximal winglet portion [0157] 142 Additional
body [0158] 142a Uplift body [0159] 142b Mass body [0160] 143
Reversal element [0161] 144 Propeller blade tip portion [0162] 145
Separation edge [0163] 146 Propeller blade shaft portion [0164] 148
Propeller blade root portion [0165] 150 Propeller blade front edge
[0166] 151 Propeller blade rear edge [0167] 1440 Tongue [0168] 1442
Bore [0169] 1444 Web [0170] a.sub.MSP-S Spacing/distance center of
mass MSP to pivot axis S [0171] a.sub.DP-S Spacing/distance center
of pressure DP to pivot axis S [0172] AS Flow [0173] D Rotation
axis [0174] DP Center of pressure [0175] EAP Effective force
application point [0176] E.sub.Max Maximum opening plane [0177]
F.sub.uplift Uplift force [0178] F.sub.centrifugal Centrifugal
force [0179] F.sub.reverse Reversed force on the reversal element
[0180] h Spacing rotation axis D to pivot axis S [0181] L.sub.P
Propeller blade longitudinal axis [0182] L.sub.shaft Longitudinal
axis of propeller blade shaft portion [0183] L.sub.W Winglet
longitudinal axis [0184] M.sub.opening Opening moment [0185]
M.sub.closing Closing moment [0186] MSP Center of mass of propeller
blade [0187] N.sub.D Normal to the rotation axis D [0188] OR
Opening direction [0189] P1 Maximum closed position of the
propeller blade/folding propeller [0190] Pm Middle open position of
the propeller blade/folding propeller [0191] P2 Maximum open
position of the propeller blade/folding propeller [0192]
r.sub.centrifugal Spacing rotation axis D to center of mass MSP
(radius of centrifugal force) [0193] R1 Outer radius of propeller
blade shaft portion [0194] R2 Outer radius of folding propeller or
curvature of cylinder [0195] S Pivot axis [0196] S.sub.U Pivot axis
of reversal element [0197] SR Closing direction [0198] U1 Maximum
folded-in position of reversal element [0199] U2 Maximum folded-out
position of reversal element [0200] .alpha. Opening angle of
propeller blade/angle between a.sub.MSP-S and E.sub.max [0201]
.beta. Inclination angle of winglet/angle between L.sub.w and
L.sub.shaft
* * * * *