[0001] The present invention relates to a watercraft propulsion unit comprising a bracket
mountable to a hull, a motor drive unit mounted to the lower end of the bracket and
locatable in the body of water and having an electric motor provided with a motor
case for driving a propeller.
[0002] A system as shown in Fig. 7 has been commonly utilized for the afore-mentioned watercraft
propulsion unit.
[0003] The system will be described with reference to the accompanying drawings
[0004] Numeral 81 designates the watercraft propulsion unit mounted on a watercraft, and
the arrow Fr shows the running direction of the water craft.
[0005] The watercraft propulsion unit 81 is provided with a bracket 82 mounted to the hull
of the watercraft, and the bracket 82, made of a long pipe and extending vertically,
is mounted, at the upper end, to the hull. The watercraft propulsion unit 81 is also
provided with a motor drive unit 83 mounted to the lower end of the bracket 82 and
located in the body of water.
[0006] The motor drive unit 83 is comprised of a casing 85 mounted to the lower end of the
bracket 82, an electric motor 86 mounted removably to the casing 85 so as to project
forwardly from the casing 85, and a propeller 87 supported by the casing 85 and driven
by the electric motor 86.
[0007] The electric motor 86 has a cylindrical motor case 89 constituting its outer shell,
the axis 90 of which extends longitudinally, and the motor case 89 is mounted detachably,
at the rear end, to the front end of the casing 85. The electric motor 86, housed
in the motor case 89, has a rotor 91 supported by the casing 85 and the motor case
89 for rotation about the axis 90. Also provided are a commutator 92 rotatable around
the axis 90 with the rotor 91, and a brush 93 mounted on the motor case 98 for slidably
engaging the commutator 92.
[0008] A control device 95 for electronically controlling the electric motor 86, and a power
source 96, a battery for the control device 95, are provided on the hull. Also provided
is a drive means 97 for electronically controlling the rotational speed of the electric
motor 86 through control of the control device 95; and the electric motor 86, control
device 95, power source 96, and drive means 97 are connected to each other with electric
wires 98.
[0009] The drive means 97 is housed in the casing 85. If the electric motor 86 is removed
from the casing 85 so as to open the opening at the front end of the casing 85, the
drive means 97 can be inserted or removed with respect to the casing 85.
[0010] When a rider operates the control device 95, a given electric power is supplied to
the electric motor 86 through the drive means 97, so that the rotational speed of
the electric motor 86 is controlled. Then, the propeller 87 is rotated in association
with the electric motor 86, so that the watercraft is propelled at a desired speed.
[0011] However, the foregoing conventional system has a following problem.
[0012] First, for reasons described below, the electric motor 86, which has a special construction,
can not be replaced with a general purpose type, so that molding of the watercraft
propulsion unit 81 for housing the electric motor 86 as a component, is very complicated,
posing a problem of a higher production cost.
[0013] The first reason: the motor case 89 of the electric motor 86, as described above,
has a special construction for mounting to the casing 85.
[0014] The second reason: since the electric motor 86 is exposed in the body of water, there
is a possibility of the electric motor 86 striking against the bottom of the water
during propulsion of the watercraft, and the impact force is applied directly to the
electric motor 86 in case of collision, which might damage the electric motor 86 easily.
Thus the wall thickness of the motor case 89 of the electric motor 86 is increased
to provide adequate impact strength.
[0015] The third reason: the motor case 89 of the electric motor 86, which is exposed to
water, tends to be oxidized, so that materials and structures are selected to prevent
corrosion.
[0016] For reasons described above, a general purpose electric motor 86 can not be incorporated
in the conventional watercraft propulsion unit 81, thereby posing a problem of complicated
molding.
[0017] Secondly, in view of the first problem, an idea can be suggested that the electric
motor 86 is housed in the casing 85 so as to cover the same so that a general purpose
type motor can be utilized for the electric motor 86.
[0018] However, if the electric motor 86 is simply covered by the casing 85, the work of
maintenance and inspection of the electric motor 86 is hindered by the casing 85,
causing a difficulty in this work.
[0019] Further, when the electric motor 86 is operated, an electric current flows between
the commutator 92 and the brush 93 which are in sliding contact with each other, so
that the commutator 92 and the brush 93 tend to generate heat. Therefore, as described
above, if the electric motor 86 is simply covered by the casing 85, heat release into
the body of water is prevented by the casing 85, which may cause a higher temperature
of the electric motor 86.
[0020] Thirdly, the electric motor 86 is protruded from the casing 85, as a whole, and the
casing 85 is mounted to the lower end of the bracket 82, so that the electric motor
86 is protruded forwardly from the bracket 82, as a whole. In this construction, however,
at the time of, for example, "shell gathering" when a fisherman on the watercraft
2 gathers, with a fishing pole, abalones or sea urchins on the bottom of the sea,
the fishing pole may interfere with the electric motor 86, thereby raising a problem
of the electric motor 86 hindering manipulation of the fishing pole.
[0021] Accordingly, it is an objective of the present invention to provide a watercraft
propulsion unit as indicated above which always ensures with simple technical means
an always reliable use of said unit under all running conditions simultaneously enhancing
the performance of maintenance and inspection and reduces the production costs.
[0022] According to the present invention, this objective is solved for a watercraft propulsion
unit as indicated above in that said motor drive unit comprising a casing forming
an outer shell thereof and mounted to said bracket, and that said electric motor accommodated
in said casing and mounted thereto.
[0023] In order to further enhance the performance of maintenance and inspection, it is
advantageous when the motor drive unit comprises an electrical equipment case mounted
to said casing for accommodating drive means controlling the rotational speed of said
electric motor.
[0024] The reason for this will be explained with respect to Fig. 7.
[0025] That is, when the drive means 97 is to be removed from the casing 85 in case of replacement
with a new one, or for maintenance or inspection, it is necessary that the electric
motor 86 is first removed from the casing 85 beforehand, and accordingly, the opening
at the front end of the casing 85 is opened.
[0026] However, since the work of removing the electric motor 86 from the casing 85, is
complicated, the work required for maintenance or inspection of the drive means 97
is also complicated.
[0027] For this reason, a method is suggested in which an electrical equipment case for
removably housing the drive means 97, is provided in addition to the casing 85 so
as to enable maintenance or inspection of the drive means 97 regardless of the electric
motor 86 being attached or detached with respect to the casing 85.
[0028] However, a mere installation of the electrical equipment case will result in an increased
fluid resistance of the motor drive unit 83 during running, which may prevent smooth
propulsion of the watercraft.
[0029] According to an advantageous embodiment of the present invention, the casing is provided
with an opening openable and closable by a cover. In that case, it is advantageous
for a further improvement of the maintenance and inspection when said opening and
said cover are provided at a front end of said motor drive unit opposite to said propeller.
[0030] In order to further enhance the cooling effects of the present invention, it is advantageous
when said electric motor comprises a rotor housed in said motor case and supported
by said motor case for rotation, an commutator rotatable with said rotor, and a brush
mounted on said motor case for slidably engaging said commutator, said motor case
being joined to said casing in the vicinity of said brush.
[0031] In that case, it is optional to provide said commutator within the casing such that
it faces to the front or to the rear as seen in the normal driving direction.
[0032] Further advantageous embodiments are given below.
[0033] According to another embodiment of the present invention, the watercraft propulsion
unit having a bracket 6 mounted to a hull 2 and a motor drive unit 8 mounted to the
lower end of said bracket 6 and located in the body of water 7, wherein said motor
drive unit 8 comprising a casing 16 forming an outer shell thereof and mounted to
said bracket 6, an electric motor 23 housed in said casing 16 and mounted thereto,
and a propeller 24 supported by said casing 16 and driven by said electric motor 23.
[0034] A further embodiment of the present invention is given by a watercraft propulsion
unit, wherein said casing 16 is formed with an opening 19 and provided with a cover
20 for opening and closing said opening 19 so that said electric motor 23 can be inserted
removably into said casing 16 through said opening 19, and said electric motor 23
is mounted removably to said casing 16.
[0035] Moreover, a watercraft propulsion unit is possible, wherein on the hull 2 is provided
a control device 47 for controlling said electric motor 23, through said bracket 6
are provided electric wires 54 for connecting said electric motor 23 and control device
47, said wires 54 being cut at the middle portion thereof, and in said casing 16 are
provided couplers 64 for disconnectably connecting said cut ends of said wires 54,
said couplers 64 being located within said opening 19 when viewed from the front of
said opening 19.
[0036] In addition, it is possible that said electric motor 23 comprises a motor case 27
constituting its outer shell, a rotor 32 housed in said motor case 27 and supported
by said motor case 27 for rotation, an commutator 35 rotatable with said rotor 32,
and a brush 36 mounted on said motor case 27 for slidably engaging said commutator
35, said motor case 27being joined to said casing 16 in the vicinity of said brush
36.
[0037] In order to further enhance the performance of said watercraft propulsion unit, it
is advantageous when said electric motor 23 is located right under said bracket 6.
[0038] Other preferred embodiments of the present invention are laid down in further dependent
claims.
[0039] In the following, the present invention is explained in greater detail with respect
to several embodiments thereof in conjunction with the accompanying drawings, wherein:
Fig. 1 is a partial enlarged sectional view of a first embodiment of a watercraft
propulsion unit shown in Fig. 2;
Fig. 2 is a general diagrammatic view of the first embodiment of the watercraft propulsion
unit;
Fig. 3 is a partially broken away rear view of the first embodiment of the watercraft
propulsion unit;
Fig. 4 is a partially broken away plan view of the first embodiment of the watercraft
propulsion unit;
Fig. 5 is an exploded view of the first embodiment shown in Fig. 1;
Fig. 6 is a view of a second embodiment, corresponding to Fig. 1; and
Fig. 7 is a view of a conventional system, corresponding to Fig. 1.
[0040] Fig. 1 through Fig. 5 show a first embodiment of this invention.
[0041] In the figure, numeral 1 designates a watercraft, and the arrow Fr shows the running
direction of the watercraft 1.
[0042] The watercraft 1 is provided with a hull 2 and a watercraft propulsion unit 4 for
propelling the hull 2 forwardly or backwardly on the surface of water 3. The water
propulsion unit 4 is comprised of a bracket 6 mounted to the rear end of the hull
2, a motor drive unit 8 mounted to the lower end of the bracket 6 and located in the
body of water 7, and a steering handle 9 mounted to the upper end of the bracket 6.
[0043] In Fig. 2, the bracket 6 is provided with a bracket body 11 mounted detachably to
the rear end of the hull 2, and a mounting pipe 12 supported by the bracket body 11.
The mounting pipe 12 extends vertically, and supported at the lengthwise middle portion
by the bracket body 11 for rotation about its axis. The motor drive unit 8 is mounted
to the lower end of the mounting pipe 12, and the steering handle 9 to the upper end
of the same.
[0044] The steering handle 9 has a box-like handle body 13 fixed to the upper end of the
mounting pipe 12, and a handle grip 14 protruding forwardly from the handle body 13;
and the handle grip 14 is supported by the handle body 13 for rotation about the axis
extending longitudinally.
[0045] In Fig. 1 through Fig. 5, the motor drive unit 8 is provided with a casing 16 constituting
its outer shell. Since the casing 16 is located in the body of water 7, it is made
of corrosion resisting alloy such as aluminum alloy. The casing 16 has a cylindrical
casing body 17 mounted to the lower end of the mounting pipe 12 of the bracket 6,
and the axis 18 of the casing body 17 extends longitudinally. The casing body 17 has,
at the front end, an opening 19 for providing communication between the inside and
outside of the casing body 17, and the opening 19, located on the axis 18, has a substantially
circular shape when viewed from the front. Also, a semi-spherical cover 20 for openably
closing the opening 19 is provided, and fastened detachably to the front end of the
casing body 17 with a pair of right and left fist fasteners 21, while at the rear
of the casing body 17 and on the inside circumferential surface of the same is formed
integrally a partition 22 for separating the inside of the casing body 17 from the
outside.
[0046] The motor drive unit 8 is provided with an electric motor 23 housed in the casing
16 and mounted removably to the same, a propeller 24 supported by the casing 16 at
the rear and driven by the electric motor 23, and a planetary gear type reduction
gear 25 supported by the casing 16 and interposed between the electric motor 23 and
the propeller 24 for transmitting power of the electric motor 23 to the propeller
24.
[0047] The electric motor 23, of a general purpose type, has a metal motor case 27 constituting
its outer shell. The motor case 27 is comprised of a cylindrical motor case body 28
on the axis 18, a front closing plate 29 for closing the front opening of the motor
case 27 , and a rear closing plate 30 for closing the rear opening of the same.
[0048] The motor case body 28 is made of ferrous ferromagnetic material; on the inside surface
of the motor case body 28 are attached magnets 31a circumferentially at regular intervals;
and the motor case body 28 and magnets 31a constitute a stator 31.
[0049] A rotor 32 is housed in the motor case 27. The rotor 32 is supported by the front
and rear closing plates 29, 30 of the motor case 27 for rotation about the axis 18,
and is comprised of an output shaft 33 supported on the axis 18 by the motor case
27, and an armature 34 fitted on the output shaft 33. Also provided is a commutator
35 rotatable around the axis 18 with the rotor 32. The commutator 35 is mounted to
the rear of the output shaft 33, and disposed axially in serial relation with the
armature 34, while on the motor case 27 is mounted a brush 36 for slidably engaging
the commutator 35.
[0050] The electric motor 23 is inserted removably in the casing 16 through the opening
19, and fastened detachably to the casing 16 with second fasteners 39. In this case,
the commutator 35 and the brush 36 of the electric motor 23 are located at the rear
end of and inside of the motor case 27, and the rear end of the motor case, or the
rear closing plate 30, is put into surface contact with the partition 22 of the casing
16, that is, the rear end portion of the motor case 27 in the vicinity of the brush
36 is joined to the casing 16.
[0051] The second fasteners 38 is comprised of a support piece 39 formed at the front end
of the motor case 27, and a bolt 40 passing through the support piece 39 and screwed
into the partition plate 22 of the casing 16. The electric motor 23 extends on and
along the axis 18, and the bolt 40 extends substantially parallel to the axis 18,
both of the electric motor 23 and the bolt 40 being positioned within the opening
19 in front view of the same (ie, the front view of the watercraft propulsion unit
4 when viewed from the front).
[0052] As a result, insertion and taking out of the electric motor 23 with respect to the
casing 16, is performed easily through the opening 19, and mounting of the electric
motor 23 to the casing 16, is also performed easily through the opening 19 by manipulating
the bolts 40 of the second fasteners 38.
[0053] Thus, assembling of the motor drive unit 8, or dismantling of the unit as shown in
Fig. 5, can be performed easily, as well as maintenance or inspection, for example,
at the time of replacement of the electric motor 23 inside the casing 16 with a new
one.
[0054] The propeller 24 is fastened removably to the casing 16 with third fasteners 43,
and the reduction gear 25 removably to the casing with fourth fasteners 44.
[0055] Inside the handle body 13 of the steering handle 9 on the hull is provided a control
device 47 for electronically controlling the electric motor 23. The control device
47 is provided with a control unit 48, a grip angle sensor 49 for detecting the rotation
angle of the handle grip. 14, and a rotation switching device 50 for switching the
direction of rotation of the electric motor 23 to a normal or a reverse one. These
components 48, 49, 50 are electrically connected to each other.
[0056] Also, a battery for supplying power to the control unit 48 of the control device
47, or a power source 52, is provided on the hull. Also provided is a drive means
53 for electronically controlling the rotational speed of the electric motor 23 through
control of the control device 47; and the electric motor 23, control device 47, power
source 52, and drive means 53 are connected to each other with electric wires 54.
Numeral 55 designates a motor current sensor.
[0057] In the upper wall of the casing body 17 of the casing 16 is formed a communication
hole 56 for providing communication between inside spaces of the mounting pipe 12
and the casing 16. As a result, inside spaces of the bracket body 11 of the bracket
6, the mounting pipe 12 of the bracket 6, the handle body 13 of the steering handle
9, and the casing 16 of the steering handle 9, are in communication with each other,
and the electric wires 54 for connecting the electric motor 23 and the control device
47, runs through the inside space of the mounting pipe 16 of the bracket 6, and the
communication hole 56.
[0058] The motor drive unit 8 has an electrical equipment case 57 mounted to the lower end
of the mounting pipe 12 of the bracket 6, and the drive means 53 is housed detachably
in the electrical equipment casing 57. The electrical equipment case 57 is comprised
of an electrical equipment case body 58 formed integrally with the upper wall of the
casing body 17 of the casing 16, and opening 58a for opening the inside of the electrical
equipment body 58 reawardly, a cover 59 for openably closing the opening 58a, and
fifth fasteners 60 for fastening the cover 59 detachably to the electrical equipment
case 58.
[0059] In the electrical equipment case 59 houses the drive means 53, which is fastened
detachably on the inside wall of the cover 59 with sixth fasteners 61. The electrical
equipment case body 58 is formed with a communication hole 62 for providing communication
between the inside spaces of the mounting pipe 12 and the electrical equipment case
57. As described above, one ends of the electric wires 54 on the drive means side
which run down from the control device 47 through the mounting pipe 12 of the bracket
6, reach the inside of the electrical equipment case 57, where they are connected
disconnectably to the drive means 53.
[0060] As shown in Fig. 5, if the fifth fasteners 60 are loosened, the drive means 53 can
be taken out from inside the electrical equipment case 57 in one body with the cover
59 and the sixth fasteners 61. In this case, the electric wires 54 have a little slack,
which allows taking in and out of the drive means 53.
[0061] The electric wires 54 are cut at the lengthwise middle portion, and a couplers 64
are provided for coupling the cut ends disconnectably. The couplers 64 are disposed
at the Inside front portion of the casing 16 between the cover 20 of the casing 16
and the front end of the electric motor 23, and positioned within the opening 19 in
front view.
[0062] The electric motor 23 is located right under the mounting pipe 12. The electrical
equipment case 57, and the drive means 53 housed therein are located rearwardly of
the lower end of the mounting pipe 12 of the bracket 6 and upwardly of the casing
16 and the electric motor 23.
[0063] When a driver operates the handle grip 14 of the steering handle 9 so as to propel
the watercraft 1, detected signals of rotation angles from the grip angle sensor 49,
and detected signals of rotational direction from the rotation switching device 50
are input to the control unit 48, a given power is supplied to the electric motor
23 through the drive means 53 controlled by the control unit 48 according to these
signals. In this case, an electric current flows from the brush 36 to the armature
34 through the commutator 35 in sliding contact with the brush 36, and the rotor 32
is rotated about the axis 18. In this way, the electric motor 23 is controlled of
its speed, and normal and reverse rotational directions.
[0064] The propeller 24 is rotated in association with the motor 23, so that the watercraft
1 is propelled at a desired speed forwardly or backwardly on the surface of water
3.
[0065] In the construction described above, the electric motor 23 is housed in the casing
16 and protected from the outside, as a whole, so that the electric motor 23 needs
only to be of a type for simply driving the propeller 24, that is, there is no need
for a motor case 27 etc with a special structure, and thus a general purpose type
is utilized for the electric motor 23 as described above.
[0066] Further, since the electric motor 23 is covered by the casing 16 so as not to he
exposed to the body of water 7, the casing 16 will prevent the electric motor 23 from
directly striking against the bottom of water during running. Therefore, it is not
necessary for the motor case 27 of the electric motor 23 to be thick enough to withstand
the impact at the time of the collision, and thus a general purpose type is utilized
for the electric motor 23.
[0067] Furthermore, the electric motor 23 is covered by the casing 16 so as not to be exposed
to the body of water 7, thereby preventing the motor case 27 from being corroded by
the water. Therefore, it is not necessary for a motor case 27 of the electric motor
23 to be made of special corrosion resistant material or to assume a corrosion proof
structure, and thus an electric motor of a general purpose type is utilized.
[0068] Moreover, as described above, especially in Fig. 5, the electric motor 23 can be
taken out from the casing 16 through the opening 19 if only the opening 19 is opened
by loosening the first fasteners 21 and removing the cover 20.
[0069] Therefore, although the electric motor 23 is housed in the casing 16, maintenance
and inspection of the electric motor 23 can be performed easily, for example, at the
time of replacement of the motor with new one.
[0070] Further, especially as shown in Fig. 5, when maintenance or inspection is performed
of the electric motor 23 housed in the casing 16, the opening 19 is first opened by
manipulating the cover 20. Then, the couplers 64, which are located inside the opening
19 as described above, can be disconnected easily through the opening 19.
[0071] If the couplers 64 are disconnected, the electric motor 23 can be taken out from
the casing 16 through the opening 19 without any interference with electric wires
54 connecting the electric motor 23 and the control device 47.
[0072] Therefore, maintenance and inspection of the electric motor 23 can be performed easily
regardless of the existence of the electric wires 54.
[0073] Yet further, when the electric motor 23 is operated, an electric current flows between
the commutator 35 and the brush 36 which are in sliding contact with each other, so
that the commutator 35 and the brush 36 tend to generate heat, thereby causing a higher
temperature of the electric motor 23.
[0074] As described above, the motor case 27 is joined to the casing 16 in the vicinity
of the brush 36. Therefore, the heat generated between the commutator 35 and the brush
36 is transmitted smoothly to the casing 16 from the motor case 27 in the vicinity
of the brush 36, and further, released efficiently into the body of water 7 from the
casing 16.
[0075] Therefore, although the electric motor 23 is housed in the casing 16, a higher temperature
of the electric motor 23 is prevented.
[0076] Further, the electric motor 23 is located right under the bracket 6 together with
the casing 16, and the electrical equipment case 57 rearwardly of the lower end of
the bracket 6.
[0077] Therefore, the casing 16, electric motor 23, and electrical equipment case 57 are
located longitudinally at substantially the same place as the bracket 6, thereby preventing
large forward or rearward projection of the casing 16, electric motor 23, and electrical
equipment case 57 from the bracket 6.
[0078] Thus, interference of the electric motor 23 etc with the fishing pole during "shell
gathering" is prevented, providing smooth "shell gathering."
[0079] Still further, as described above, the electric motor 23 is located right under the
bracket 6, so that the length of the electric wires 54 which run from the control
unit 47 to the electric motor 23 through the bracket 6, can be kept small, thereby
effecting easy wiring.
[0080] Yet further, as described above, the motor drive unit 8 has the electrical equipment
case 57 mounted to the casing 16, and the drive means 53 is housed detachably in the
electric equipment case 57.
[0081] Therefore, when the drive means 53 is to be detached for maintenance or inspection,
conventional preparatory work of removing the electric motor 23 is not necessary.
[0082] Thus, the drive means 53 can be attached or detached whether the electric motor 23
is mounted or not, so that maintenance and inspection of the drive means 53 can be
performed easily.
[0083] Further, the electrical equipment case 57 is located rearwardly of the lower end
of the bracket 6.
[0084] Therefore, when the electrical equipment case 57 is provided, it is covered behind
the lower end of the bracket 6, thererby preventing increased fluid resistance of
the electrical equipment case 57 during propulsion of the watercraft 1.
[0085] Thus, as described above, although the drive means 53 is arranged so that its maintenance
and inspection can be performed easily, smooth propulsion of the watercraft 1 is ensured.
[0086] In addition, the electrical equipment case 57 is located upwardly of the casing 16,
so that the casing 16 prevents the electrical equipment case 57 from striking the
bottom of the water during propulsion of the watercraft 1.
[0087] Therefore, the drive means 53, which is housed in the electrical equipment case 57
and whose impact resistance is small, is protected reliably from the impact force
due to the collision.
[0088] Fig. 6 shows a second embodiment.
[0089] Referring to the figure, the commutator 35 of the electric motor 23 is mounted to
the front end of the output shaft 33, so that the commutator 35 and the brush 36 is
located at the front end portion inside the motor case 27. On the other hand, the
support piece 39 is formed integrally on the outer surface of the motor case 27 in
the vicinity of the brush 36, and joined to the front end of the casing body 17 of
the casing 16 in surface contact relation. That is, the front portion of the motor
case 27 in the vicinity of the brush 36 is joined to the casing 16.
[0090] Other structures and functions of the embodiment are the same as those of the first
embodiment, thus like parts are designated by like reference numerals, and descriptions
are omitted.
[0091] Effects of this invention are as follows:
[0092] According to one embodiment of the invention, a watercraft propulsion unit having
a bracket mounted to a hull and a motor drive unit mounted to the lower end of said
bracket and located in the body of water, is characterized in that said motor drive
unit comprising a casing forming an outer shell thereof and mounted to said bracket,
an electric motor housed in said casing and mounted thereto, and a propeller supported
by said casing and driven by said electric motor.
[0093] Therefore, the electric motor needs only to be of the type for simply driving the
propeller, that is, there is no need for a special construction, and thus a general
purpose electric motor can be utilized.
[0094] Further, since the electric motor is covered by the casing so as not to be exposed
to the body of water, the casing will prevent the electric motor from directly striking
against the bottom of water during running. Therefore, it is not necessary for the
motor case of the electric motor to be thick enough to withstand the impact at the
time of the collision, and thus a general purpose electric motor can be utilized.
[0095] Furthermore, the electric motor is covered by the casing so as not to be exposed
to the body of water, thereby preventing the motor case from being corroded by the
water. Therefore, it is not necessary for a motor case of the electric motor to be
made of special corrosion resistant material or to assume a corrosion proof structure,
and thus a general purpose electric motor can be utilized.
[0096] For reasons as described above, since a general purpose electric motor can be utilized,
easy molding can be achieved of the motor drive unit for housing the electric motor
as a component, as well as a lower production cost.
[0097] According to another embodiment of the invention, a watercraft propulsion unit is
characterized in that said casing is formed with an opening and provided with a cover
for opening and closing said opening so that said electric motor can be inserted removably
into said casing through said opening, and said electric motor is mounted removably
to said casing.
[0098] Therefore, the electric motor, which is housed in the casing, can be taken out from
the casing through the opening if only the opening is opened by removing the cover.
[0099] Thus, although the electric motor is housed in the casing, maintenance and inspection
of the electric motor can be performed easily, for example, at the time of replacement
of the motor with new one.
[0100] According to a further embodiment of the invention, a watercraft propulsion unit
is characterized in that on the hull is provided with a control device for controlling
said electric motor, through said bracket are provided electric wires for connecting
said electric motor and a control device, said wires being cut at the middle portion
thereof, and in said casing are provided couplers for disconnectably connecting said
cut ends of said wires, said couplers being located within said opening when viewed
from the front of said opening.
[0101] Therefore, when maintenance or inspection of the electric motor housed in the casing,
is to be performed, if the opening is first opened by manipulating the cover, the
couplers, which are located inside the opening as described above, can be disconnected
easily through the opening.
[0102] If the couplers are disconnected, the electric motor can be taken out easily outside
of the casing through the opening without interference with the wires connecting the
electric motor and the control device.
[0103] Therefore, maintenance and inspection of the electric motor can be performed easily
regardless of the existence of the electric wires.
[0104] According to a still further embodiment of the invention, a watercraft propulsion
unit is characterized in that said electric motor comprises a motor case constituting
its outer shell, a rotor housed in said motor case and supported by said motor case
for rotation, an commutator rotatable with said rotor, and a brush mounted on said
motor case for slidably engaging said commutator, said motor case being joined to
said casing in the vicinity of said brush.
[0105] In this case, when the electric motor is operated, an electric current flows between
the commutator and the brush which are in sliding contact with each other, so that
the commutator and the brush tend to generate heat, thereby causing a higher temperature
of the electric motor.
[0106] However, as described above, the motor case is joined to the casing in the vicinity
of the brush.
[0107] Thus, the heat generated between the commutator and the brush is transmitted smoothly
to the casing from the motor case in the vicinity of the brush, and further, released
efficiently into the body of water from the casing.
[0108] As a result, the electric motor, though housed in the casing, is cooled down effectively
without hindrance by the casing, preventing a higher temperature of the electric motor.
[0109] According to still another embodiment of the invention, a watercraft propulsion unit
is characterized in that said electric motor is located right under said bracket.
[0110] Therefore, the bracket and electric motor are located longitudinally at substantially
the same place, thereby preventing large forward projection of the electric motor
from the bracket.
[0111] Thus, interference of the electric motor with the fishing pole during "shell gathering"
is prevented, which provides smooth "shell gathering."
[0112] Still further, as described above, the electric motor is located right under the
bracket, so that the length of the electric wires which run from the control unit
to the electric motor through the bracket can be kept small, thereby effecting easy
wiring.
[0113] Effects of this invention are as follows:
[0114] According to another embodiment of the invention, a watercraft propulsion unit provided
with a bracket mounted to a hull and a motor drive unit mounted to the lower end of
said bracket and located in the body of water, said motor drive unit having a casing
mounted to said bracket, an electric motor mounted removably to said casing, a propeller
mounted to said casing and driven by said electric motor, and drive means for controlling
the rotational speed of said electric motor, is characterized in that said motor drive
unit is provided with an electrical equipment case mounted to said casing, and said
drive means is housed detachably in said electrical equipment case.
[0115] Therefore, when the drive means is to be detached for maintenance or inspection,
conventional preparatory work of removing the electric motor is not necessary.
[0116] Thus, the drive means can be attached or detached whether the electric motor is mounted
or not, so that maintenance and inspection of the drive means can be performed easily.
[0117] According to a further embodiment of the invention, a watercraft propulsion unit
is characterized in that said electrical equipment case is located rearwardly of the
lower end of said bracket and upwardly of said casing.
[0118] Therefore, when the electrical equipment case described in the invention of claim
1, is provided, it is covered behind the lower end of the bracket, thererby preventing
increased fluid resistance of the electrical equipment case during propulsion of the
watercraft.
[0119] Thus, as described above, notwithstanding the drive means being arranged so that
its maintenance and inspection can be performed easily, smooth propulsion of the watercraft
is ensured.
[0120] Further, as described above, the electrical equipment case is located upwardly of
the casing, so that the casing prevents the electrical equipment case from striking
the bottom of the water during propulsion of the watercraft.
[0121] Therefore, the drive means, which is housed in the electrical equipment case and
whose impact resistance is small, is protected reliably from the impact force due
to the collision.
1. A watercraft propulsion unit (4) comprising a bracket (6) mountable to a hull (2),
a motor drive unit (8) mounted to the lower end of the bracket (6) and locatable in
the body of water (7) and having an electric motor (23) provided with a motor case
(27) for driving a propeller (24), characterized in that said motor drive unit (8) comprising a casing (16) forming an outer shell thereof
and mounted to said bracket (6), and that said electric motor (23) accommodated in
said casing (16) and mounted thereto.
2. A watercraft propulsion unit, in particular according to claim 1, characterized in that the motor drive unit (8) comprising an electrical equipment case (57) mounted to
said casing (16) for accommodating drive means (53) controlling the rotational speed
of said electric motor (23).
3. A watercraft propulsion unit according to claim 1 or 2, characterized in that said casing (16) being provided with an opening (19) openable and closable by a cover
(20).
4. A watercraft propulsion unit according to claim 3, characterized in that said opening (19) and said cover (20) are provided at a front end of said motor drive
unit (8) opposite to said propeller (24).
5. A watercraft propulsion unit according to at least one of the preceding claims 1 to
4, characterized by a control device (47) providable on the hull (2) for controlling said electric motor
(23) via electric wires (54) arranged in said bracket (6).
6. A watercraft propulsion unit according to claim 5, characterized in that said wires (54) are detachably connectable via couplers (64) positioned within said
case (16) close to said opening (19).
7. A watercraft propulsion unit according to at least one of the preceding claims 1 to
6, characterized in that said electric motor (23) comprises a rotor (32) housed in said motor case (27) and
supported by said motor case (27) for rotation, an commutator (35) rotatable with
said rotor (32), and a brush (36) mounted on said motor case (27) for slidably engaging
said commutator (35), said motor case (27) being joined to said casing (16) in the
vicinity of said brush (36).
8. A watercraft propulsion unit according to at least one of the preceding claims 1 to
7, characterized in that said electric motor (23) is located right beneath said bracket (6).
9. A watercraft propulsion unit according to at least one of the preceding claims 2 to
8, characterized in that said electrical equipment case (57) is located between the lower end of said bracket
(6) and said propeller (24) and upwardly of said casing (16).
10. A watercraft propulsion unit according to at least one of the preceding claims 3 to
9, characterized in that said opening (19) has a substantially circular shape and that said cover (20) has
a semi-spherical shape.
11. A watercraft propulsion unit according to at least one of the preceding claims 1 to
10, characterized in that said motor case (27) comprising a cylindrical motor case body (28) having the same
longitudinal axis (18) as the motor drive unit (8), a front closing plate (29) and
a rear closing plate (30).
12. A watercraft propulsion unit according to at least one of the preceding claims 2 to
11, characterized in that said electrical equipment case (57) comprising an electrical equipment case body
(58) detachably closable by a cover (59), said drive means (53) are detachably connected
to said cover (59).
13. A watercraft propulsion unit according to claim 12, characterized in that said electrical equipment case body (58) is integrally formed with the upper wall
of a casing body (17) of said casing (16).
14. A watercraft propulsion unit according to at least one of the preceding claims 7 to
13, characterized in that said commutator (35) is located at the side of said electric motor (23) facing the
propeller (24) or at the side of the electric motor (23) opposite to said propeller
(24).
15. A watercraft propulsion unit according to at least one of the preceding claims 1 to
14, characterized in that said electric motor is a customary electric motor (23).