NZ754539A - Waterjet Propulsion Apparatus - Google Patents
Waterjet Propulsion ApparatusInfo
- Publication number
- NZ754539A NZ754539A NZ754539A NZ75453919A NZ754539A NZ 754539 A NZ754539 A NZ 754539A NZ 754539 A NZ754539 A NZ 754539A NZ 75453919 A NZ75453919 A NZ 75453919A NZ 754539 A NZ754539 A NZ 754539A
- Authority
- NZ
- New Zealand
- Prior art keywords
- propulsion
- motor
- path
- passages
- flow
- Prior art date
Links
- 239000012530 fluid Substances 0.000 claims abstract description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000000919 ceramic Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 3
- 239000004593 Epoxy Substances 0.000 claims description 2
- 238000000149 argon plasma sintering Methods 0.000 claims description 2
- 125000003700 epoxy group Chemical group 0.000 claims description 2
- 238000010276 construction Methods 0.000 abstract description 5
- 238000001816 cooling Methods 0.000 description 4
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 210000001138 Tears Anatomy 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000000789 fastener Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000010146 3D printing Methods 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
Abstract
A waterjet propulsion apparatus comprising a motor (7), an impeller (6) driven by the motor (7) via a drive shaft (8), and a power source. A fluid flow-path (10) is formed through the apparatus, the flow-path (10) extending from at least one fluid inlet (9), through two propulsion passages (3), each propulsion passage (3) extending from a propulsion inlet to an outlet (4) located at a rear end of the apparatus. The impeller (6) is located within the flow-path (10), after the at least one fluid inlet (9), and before the propulsion inlet of the each of the propulsion passages (3). The motor (7) is located outside of the flow-path (10), between the two propulsion passages (3), and behind the impeller (6). The apparatus is advantageous in that it provides a compact and lightweight construction that can, for example, be used as part of a personal marine propulsion device (1) that can be used by an individual. propulsion passage (3) extending from a propulsion inlet to an outlet (4) located at a rear end of the apparatus. The impeller (6) is located within the flow-path (10), after the at least one fluid inlet (9), and before the propulsion inlet of the each of the propulsion passages (3). The motor (7) is located outside of the flow-path (10), between the two propulsion passages (3), and behind the impeller (6). The apparatus is advantageous in that it provides a compact and lightweight construction that can, for example, be used as part of a personal marine propulsion device (1) that can be used by an individual.
Description
TITLE
Waterjet Propulsion Apparatus
DESCRIPTION
Field of the Invention
The present invention relates to a waterjet propulsion apparatus. The apparatus is
particularly suitable for use in a personal marine propulsion device (sometimes known
as dive propulsion vehicles) that can be held by an individual or otherwise attached to
an individual to aid their propulsion through and under water. Such devices are
generally used for leisure purposes but also have applications in any other situation in
which it might be desirable to propel an individual through water without the use of a
larger vehicle.
Background
Various personal marine propulsion devices are currently known. Typically, such
devices consist of a propeller driven by a motor and a power supply contained within a
watertight housing. The propeller is generally external to the housing but contained
within a casing that allows water to be drawn through the propeller but protects the user
from coming into contact with the propeller. The devices generally have handles formed
on an outer surface of the housing to allow a user to hold onto the device during use.
When in use, a user will hold the device out in front of them or between their legs in
order to propel themselves through the water. These devices are relatively inefficient
and provide only weak propulsion.
More recently personal marine propulsion devices using waterjet, rather than propeller,
propulsion have become available. Waterjet propulsion is the method of propulsion
utilised in jetskis. In waterjet propulsion, water is drawn through a flow-path formed
through a device by means of an impeller located within the flow-path. Typically the
flow-path consists of a passage having a single intake and a single outlet and the
impeller is located centrally within the passage. Steering is achieved by changing the
direction in which water leaving the outlet is directed using one or movable steering
flaps or other equivalent means located in or at the outlet. The intake is generally
positioned ahead of the impeller and is, for example, positioned on the lower side of a
jetski. In a typical waterjet propulsion system the motor is positioned directly in front
of the impeller outside of the flow-path and drives the impeller by means of a drive
shaft that extends into the flow-path. In order to allow this construction the flow-path
will typically deviate beneath or to the side the motor and the intake will be positioned
beneath or to the side of the motor.
Personal marine propulsion devices having waterjet propulsion are desirable as the
propulsion is generally more powerful and safer than propeller propulsion. However,
the length of flow-path required to achieve efficient waterjet propulsion has been
considered to make waterjet propulsion generally unsuitable for personal marine
propulsion devices. In particular, currently available devices are excessively large
and/or heavy.
Summary of the Invention
The present invention provides a waterjet propulsion apparatus for a propulsion device
comprising a motor, an impeller driven by the motor via a drive shaft, and a power
source; wherein:
a fluid flow-path is formed through and contained within the apparatus, the
flow-path extending from at least one fluid inlet located at a front end of the apparatus
through two propulsion passages, each propulsion passage extending from a propulsion
inlet to an outlet located at a rear end of the apparatus;
the impeller is located within the flow-path, after the at least one fluid inlet, and
before the propulsion inlet of the each of the propulsion passages; and
the motor is located outside of the flow-path, within a rear portion of the
apparatus, between the two propulsion passages, and behind the impeller.
The present invention is advantageous in that it provides a waterjet propulsion
apparatus that has a construction that allows it to be made to be very lightweight and
compact, or it at least provides a consumer with a useful choice. For example, the
waterjet apparatus is suitable for use in a personal marine propulsion device and would
allow such a device to be constructed to be lightweight and compact enough for it to be
used by an individual without difficulty. The positioning of the motor at the rear of the
apparatus the two propulsion passages results in a compact construction that can be
significantly shorter in length than waterjet propulsion devices according to the prior
art. Further, the flow-path having two propulsion passages after the impeller, rather than
a single passage, allows the flow-path after the impeller to be provided in a more
compact manner as compared to the prior art without reducing the outlet area, whilst
still providing stable and directed propulsion.
The structure of the apparatus of the present invention also ensures that the fluid inlets
can be substantially unobstructed by any other part of the apparatus. In particular, there
is no need for any fluid inlet to deviate around the motor and/or the drive shaft as both
the drive shaft and impeller are located behind, rather than in front of, the impeller.
The apparatus of the present invention comprises a suitable power source for driving
the motor. In embodiments of the invention the power source may be a compact battery,
such as used in similar existing apparatus.
In order to achieve a strong and directed thrust from the outlets of the propulsion
passages, each propulsion passage may progressively reduce in cross-section from its
propulsion inlet to its outlet. Forming the propulsion passages in this manner is
advantageous in that results in a controlled decrease in pressure along each passage,
and an increased velocity of the water exiting the propulsion passages, which can
provide improved thrust at the outlets of the propulsion passage.
In order to achieve well directed thrust from the outlets of the propulsion passages said
outlets may be substantially cylindrical, rectangular or any other suitable shape. If the
apparatus of the present invention is used in a personal marine propulsion device there
is no requirement for the apparatus or device to comprise means to change the direction
of the water leaving the outlets of the propulsion passages. If no such means are present
then a device comprising the apparatus of the present invention can be steered by the
user directing the device appropriately. However, embodiments of the invention may
comprise steering means located at or adjacent the outlets of the propulsion passages in
order to vary the direction of the water exiting the outlets and thereby steer a device
comprising the apparatus. Any such steering means can be formed in any manner
apparent to the person skilled in the art, for example in the manner in which steering
means of conventional jetskis are formed.
The propulsion passages may be formed in any manner apparent to the person skilled
in the art. In embodiments of the invention both propulsion passages may be defined
by a unitary splitter component that is mounted within the housing. For example, the
unitary splitter may be a moulded component. In such embodiments the motor may be
directly mounted to the splitter and the drive shaft will extend through the splitter into
the flow-path.
In order to provide sufficient cooling to the motor when the apparatus is in use the
apparatus may further comprise a heat-sink such as a heat conductive casing or heat
exchanger that is in direct or indirect thermal connection with the motor and is arranged
such that an outer surface of the heat sink is in direct contact with water when the
apparatus is in use and submerged. In particular, it is advantageous that any such heat
sink is not completely enclosed within any housing of the apparatus but includes a heat
exchanger surface that is directly in contact with water when the apparatus is in use and
submerged. As will be readily appreciated any such heat exchanger surface is
advantageously arranged such that a user will not easily come into contact with the heat
exchanger surface when a device comprising the apparatus is in use.
In order to minimise radial flow of water exiting the outlets of the propulsion passages
it is advantageous that radially extending fins are located within the propulsion
passages. In embodiments of the invention each propulsion passage may have one or
more, preferably at least four, equally circumferentially spaced radially extending fins.
The apparatus may further comprise a housing substantially containing the components
of the apparatus and wherein the at least one fluid inlet is formed at a front end of the
housing and the outlets of the propulsion passages are formed at a rear end of the
housing.
A housing of an apparatus of the present invention may be formed in any suitable
manner. If the apparatus forms part of a personal marine propulsion device the housing
may be formed such that it can be used by an individual in a simple manner. For
example, the housing may have one or more handles located on an outer surface to
allow a user to hold on to the device when in use. Alternatively or additionally the
housing may be formed as a back-pack and comprise one or more straps to allow a user
to wear the device as a back-pack.
The components of the invention may be mounted to a housing in any suitable manner.
In embodiments of the invention one or more of the components may be mounted to
the housing by vibration mounts to reduce noise of the apparatus during operation and
to reduce wear and tear of the components during operation of the apparatus. In
embodiments of the invention the propulsion passages may be mounted to a housing by
means of vibration mounts, this may be particularly advantageous if the propulsion
passages are defined within a splitter formed as a unitary component.
The impeller of the present invention may be formed in any suitable manner. In
embodiments of the invention the impeller may be formed by 3D printing using solid
laser sintering.
The drive shaft of the apparatus of the present invention may be mounted within the
apparatus in any manner apparent to the skilled person. Typically, the drive shaft will
be mounted within one or more bearings. Such bearings may be of any suitable type
including, but not limited to, waterproof bearings or ceramic bearings. Ceramic
bearings may be preferred as waterproof sealing is not required thereby reducing the
cost and complexity of the apparatus. The drive shaft may be mounted within the
apparatus by means of one or more thrust bearings that act to transfer thrust from the
drive shaft to the apparatus. Alternatively or additionally, the drive shaft may be
mounted within the apparatus within one or more brass bushes.
The motor of the apparatus may be a waterproof motor that can be operated in direct
contact with water. This may be preferred as it is not necessary to mount such motors
in waterproof casing and waterproof motors can be operated in direct contact with water
to provide cooling to the water, thereby reducing the need for complex and/or heavy
heat sinks.
In order to prevent solid objects entering the fluid flow-path embodiments of the
invention comprise a rigid mesh provided completely across the at least one fluid Inlet.
A rigid mesh may be formed of any suitable material. In embodiments of the invention
a rigid mesh formed of plastic coated metal is provided. This may be preferred as it can
provide a sufficiently rigid and strong structure whilst also providing good corrosion
resistance. A rigid mesh may have a hexagonal mesh. If formed of appropriate material
a rigid mesh may be heat-staked to the at least one fluid inlet in order to avoid gaps or
protruding edges around edges of the mesh, which could affect flow efficiency through
the fluid flow-path.
In order to provide strength to the at least one fluid inlet and/or to help direct fluid flow
through the fluid flow-path an intake grate may be provided in the at least one fluid
inlet. An intake grate may comprise one or more support members extending across the
at least one fluid inlet and arranged to extend in a direction of fluid flow through the at
least one fluid inlet. Providing a suitably formed intake grate can increase laminar flow
through the at least one fluid inlet. An intake grate can extend across a height of the at
least one fluid inlet to transfer force to the intake grate and thereby prevent damage to
the at least one fluid inlet during operation of the apparatus. An intake grate can be
mounted within an at least one fluid inlet in any appropriate manner including, but not
limited to, fastening bolts at or near a periphery of the intake grate.
Further features and advantages of the present invention will be apparent from the
preferred embodiment that is shown in the Figures and described below.
Drawings
Figure 1 is an image of a device according to an embodiment of the present invention;
Figure 2 is a partial cross-section of components of the embodiment of Figure 1;
Figure 3 is a three-dimensional view of a splitter of the embodiment of Figures 1; and
Figure 4 is a side view of components of the embodiment of the previous Figures.
A personal marine propulsion device 1 substantially consisting of a waterjet propulsion
apparatus according to an embodiment of the present invention is shown in the Figures.
An upper side of the complete device 1 is shown in Figure 1. The housing 2 encloses
most of the components of the device 1 such that all that is visible in Figure 1 are outlets
4 of propulsion passages 3, a fluid inlet 9, and a top part 26 of the fluid inlet 9. Internal
components of the device are illustrated in the other Figures and described further
below. The housing 2 is formed of plastic and is moulded to substantially enclose the
internal components. The device 1 is formed as a backpack and comprises shoulder
straps (not shown) attached to a lower side of the housing 2 to allow the device to be
worn by a user. A battery pack (not shown) is mounted within the housing to power a
motor 7.
A partial cross-section through components of the device 1 of Figure 1 is shown in
Figure 2. In particular, this Figure illustrates the relative positioning of an impeller 6, a
motor 7, a drive shaft 8, the propulsion passages 3, and the fluid inlet 9. A pre-mesh
part 9.1 of the fluid inlet and a post-mesh part of the fluid inlet are shown. A flow path
of fluid passing through the device 1 when it is in use is also shown.
An intake mesh 21 is position in the fluid inlet 9 and acts to prevent solid objects
entering the flow path 10. The intake mesh 21 is a hexagonal mesh formed of epoxy
coated metal that is heat staked to the fluid inlet 9 for strength and to minimise any gaps
or protruding edges that could affect flow efficiency through the flow path 10. The
intake mesh extends completely across the fluid inlet 9.
An intake grate 22 is also provided within the fluid inlet. The intake grate 22 comprises
three vertically oriented plates that extend along the flow path 10 from a rear side of
the intake mesh 21. The intake grate 22 is formed of a thin corrosion resistant material
and each plate is bolted within the fluid inlet 9 at a bottom end and are fixed in position
at an upper end by means of a fastening bolt 27 that extends through each plate. The
intake grate 22 provides support to the top part 26 of the fluid inlet by transferring
vertical force away from said top part 26. The intake grate 22 also acts to improve
laminar flow through the flow path 10, thereby increasing the efficiency of the
apparatus.
The flow path 10 through the device is defined by the fluid inlet 9, the impeller 6 and a
splitter 11, which itself defines the propulsion passages 3. Details of the splitter 11 are
best seen in Figure 3. Both the fluid inlet 9 and the splitter 11 are unitary moulded
components and the fluid inlet 9 and the splitter 11 are connected together around the
impeller 6. The splitter 11 and the fluid inlet 9 may be 3D printed components. The
unitary moulding of the splitter 11 allows a bearing seat 24 to be formed in which
ceramic bearings 13.1, 13.2 of the drive shaft 8 are slotting into position. A radial
groove in the splitter 11 also allows a securing ring 23 to be positioned around an outer
end of the drive shaft 8.
The impeller 6 is located directly in front of the motor 7 and is driven by the motor 7
by means of the drive shaft 8, which extends from the motor, to the impeller. The
impeller 6 is connected to the drive shaft 8 by means of a shaft fastener 19. The drive
shaft 8 is mounted in the splitter 11 by means of two ceramic bearings 13.1, 13.2 that
allow the drive shaft to freely rotate. In particular, the drive shaft 8 is mounted within
a radial bearing 13.1 and an angular bearing 13.2. Ceramic bearings are used as they do
not require watertight sealing. The motor 7 is fixed to the splitter 11 at a front end of
the motor. The motor 7 is located between the propulsion passages 3 of the splitter 11.
The motor 7 is a waterproof motor that is used in direct contact with water when the
apparatus 1 is in use. Contact with water acts to cool the motor 7 such that no heat sink
or other cooling means is required.
The propulsion passages 3 of the splitter 11 are positioned either side of the motor 7
and each extend from a propulsion input immediately behind the impeller 6 to an output
4 at a rear end of the device 1. The propulsion passages 3 are substantially
symmetrically positioned within the splitter 11 and are mirror images of one another.
The propulsion passages 3 are substantially circular in cross-section and gradually
reduce in diameter from their propulsion input to their output 4. This reduction in
diameter helps increase and direct thrust generated by the device 1. Each propulsion
passage 3 has six radially extending fins 14 located therein in order to reduce the radial
flow of water exiting the passages and to thereby preserve the thrust generated by the
impeller 6. As the device 1 is intended for use as a backpack the device 1 does not
include steering means. Instead the device 1 can be steered by the user orienting their
body appropriately.
Further details of the device 1 can be seen in Figure 4. In particular Figure 4 shows the
relative position of the splitter 11, the motor 7, the mesh 21, and an intake grate 22. As
can be clearly seen, the motor 7 is positioned between the propulsion passages 3 of the
splitter 11. The motor 7 is positioned and the housing 2 are formed such that an outer
surface of the motor 7 is in direct contact with water when the device 1 is in use and
submerged and thereby provide cooling to the motor. The motor 7 is fixed to a motor
mount 20 at a front end. The motor mount 20 is in turn fixed to the splitter 11 to thereby
hold the motor 20 in an appropriate position. The motor 20 is connected to the drive
shaft 8 by means of a shaft coupler 15. A shoulder 25 is provided on the drive shaft 8
adjacent the shaft coupler 15 to locate the drive shaft 8 in position within the angular
bearing 13.2.
The splitter 11 is connected to the housing 2 by means of four joint profiles 17 provided
on each lateral side of the splitter 11. The joint profiles 17 have eyelets 18 through
which the splitter 11 can be mounted to the housing 2 by vibration mounts (not shown)
that act to reduce noise and to reduce wear and tear.
When in use the impeller 6 is driven by the motor 7 to rotate via the drive shaft 8. The
motion of the impeller 6 creates a reaction force from water, which is transferred axially
into the drive shaft 8 via the shaft fastener 19. The shaft shoulder 25 transfers the thrust
into the angular bearing 13.2. The thrust transferred into the angular bearing 13.2, from
there the reaction force is transferred via the bearing seat 24 into the splitter 11 and then
into the housing 2 via the joint profiles 17.
In use the device 1 is strapped to a user’s back and when the user is submerged in water
it is turned on. The impeller 6 is then driven by the motor 7 via the drive shaft 8 to draw
water through the flow-path 10. In particular, water is drawn in the fluid inlet 9, through
the impeller 6 and out of the device via the propulsion passages 3. This provides a
waterjet propulsion system that acts to propel the user forward. By controlling the
Speedof the motor 7 the propulsion provided can be controlled appropriately. The user
can then steer themselves by moving their body appropriately. In order that a user can
control the speed of the motor and can turn the motor on and off control means (not
shown) are provided as a handheld controller.
Unless the context requires otherwise the word ‘comprise’, and variations including
‘comprises’ and ‘comprising’ are intended to be inclusive rather than exclusive. In
other words, comprise (and variations) is to be taken to mean include and not ‘consists
only of’ unless the context specifically precludes this interpretation.
Claims (20)
1. A waterjet propulsion apparatus for a propulsion device comprising a motor, an impeller driven by the motor via a drive shaft, and a power source; wherein: a fluid flow-path is formed through and contained within the apparatus, the flow-path extending from at least one fluid inlet located at a front end of the apparatus through two propulsion passages, each propulsion passage extending from a propulsion inlet to an outlet located at a rear end of the apparatus; the impeller is located within the flow-path, after the at least one fluid inlet, and before the propulsion inlet of the each of the propulsion passages; and the motor is located outside of the flow-path, within a rear portion of the apparatus, between the two propulsion passages, and behind the impeller.
2. An apparatus according to claim 1, wherein each propulsion passage reduces in cross-section from its propulsion inlet to its outlet.
3. An apparatus according to claim 1 or claim 2, wherein the outlets of the propulsion passages are substantially cylindrical or rectangular.
4. An apparatus according to any one of the preceding claims, wherein the propulsion passages are defined within a splitter formed as a unitary component.
5. An apparatus according to claim 4, wherein the motor is mounted to the splitter and the drive shaft extends through the splitter into the flow-path.
6. An apparatus according to any one of the preceding claims, further comprising a heat-sink that is in thermal connection with motor and is arranged such that the heat sink is in direct contact with water when the device is in use.
7. An apparatus according to any preceding claim, wherein radially extending fins are located within the propulsion passages to direct water expelled from the device.
8. An apparatus comprising a housing substantially containing the components of the apparatus and wherein the at least one fluid inlet is formed at a front end of the housing and the outlets of the propulsion passages are formed at a rear end of the housing.
9. An apparatus according to claim 8, wherein the housing has one or more handles located on an outer surface to allow a user to hold on to the device when in use.
10. An apparatus according to claim 8 or 9 wherein the housing is formed as a back- pack and comprises one or more straps to allow a user to wear the device.
11. An apparatus according to any one of claims 8 to 10, wherein one or more components of the apparatus are mounted to the housing by means of vibration mounts.
12. An apparatus according to any one of the preceding claims, wherein the impeller is formed by solid laser sintering.
13. An apparatus according to any one of the preceding claims, wherein the drive shaft is mounted within the apparatus on ceramic bearings.
14. An apparatus according to any one of the preceding claims, wherein the drive shaft is mounted within the apparatus by means of at least one thrust bearing.
15. An apparatus according to any one of the preceding claims, wherein the motor is water-proof and can be operated when in direct contact with water.
16. An apparatus according to any one of the preceding claims, wherein a rigid mesh is provided across the at least one fluid inlet to prevent solid objects entering the fluid flow-path.
17. An apparatus according to claim 16, wherein the mesh is heat-staked to the fluid inlet.
18. An apparatus according to claim 15 or claim 16, wherein the mesh is formed of epoxy coated metal.
19. An apparatus according to any one of the preceding claims, wherein a grating is provided in the at least one fluid inlet.
20. A personal marine propulsion device comprising a waterjet propulsion apparatus according to any one of the preceding claims.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB1809698.2 | 2018-06-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
NZ754539A true NZ754539A (en) |
Family
ID=
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