Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MARINE PROPULSION DEVICE
INCLUDING AN OVERDRIVE TRANSMISSION
BACKGROUND OF THE INVENTION
:
The in~ention relates to transmissions and,
j more particularly, to overdrive transmissions for
marine propulsion devices and the like.
' With increasing horsepower of marine
propulsions devices, such as outboard motors and stern
drive units, the use of an overdrive unit becomes more
desirable to improve fuel economy, engine life, lower
unit life, and overall performance. A lower pitch
propeller can be used for acceleration and, after the
boat is planning, an overdrive can be activated to
permit the engine speed to be lowered without
decreasing the propeller speed. Higher drive shaft
speeds made possible when operating in the overdrive
mode result in lower torque loading between the drive
gear on the drive shaft and the pinion gears on ~he
propeller shaft with an increase in the life of the
lower unit and fuel economy.
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Examples of other constructions of multi-speed
transmissions are disclosed in the following United States
patents:
PATENTS PATENT NO. ISSUE DATE
Molly 1,795,135 March 3, 1931
Pilaar 1,979,077 Oct. 30, 1934
Kohr 2,466,318 April 5, 1949
Kreidler 2,861,461 Nov. 25, 1958
Halberg et al. 3,129,602 April 21, 1964
Orcutt et al. 3,372,601 March 12, 1968
Avramidis et al. 3,884,097 May 20, 1975
Strang 4,173,939 Nov. 13, 1979
SUMMARY OF THE INVENTION
The invention provides a transmission including a
rotatably mounted input shaft, a drive shaft mounted for
rotation coaxially with and independently of the input shaft, a
first drive gear mounted for common rotation with the input
shaft, a first driven gear mounted for common rotation with the
drive shaft, clutch means drivingly connecting the input shaft
to the drive shaft for affording common rotation of the input
shaft and the drive shaft in one rotary direction and for
permitting rotation of the drive shaft relative to the input
shaft when the drive shaft is driven in the one rotary
direction at a rate of rotation higher than that of the input
shaft, a second driven gear meshing with the first drive gear,
a second drive gear mounted for rotation coaxially with and
relative to the second driven gear and meshing with the first
driven gear, the gear ratios of the gears being such that the
drive shaft is driven at a rotational speed greater than that
of the input shaft when the second driven gear and the second
drive gear are drivingly connected together, and actuating
means operably connected between the second driven gesr and the
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~.; drive gear and movable between a first position wherein the
^~ second driven gear and the second drive gear are freely
. rotatable relative to each other and a second position wherein
t a dxiving connection is establlshed between the seaond driven
~; gear and the second drive gear.
?~i: The invention also provides a marine propulsion
;~ device including a rotatably mounted input shaft drivingly
. connected to a power source, a lower unit housing a drive
shaft, a propeller shaft rotatably mounted in the lower unit
and carrying a propeller, means drivingly connecting the drive
shaft to the propeller shaft, and a transmission drivingly
connecting the input shaft to the drive shaft, which
~ transmission includes a first drive gear mounted for common
s rotation with the input shaft, a first driven gear mounted for
common rotation with the drive shaft and for rotation coaxially
with and independently of the input shaft, clutch means
drivingly connecting the input shaft to the drive shaft for
~ affording common rotation of the input and drive shafts in one
s rotary direction and for permitting rotation of the drive shaft
,r relative to the input shaft when the drive shaft is driven in
r the rotary direction at a rate of rotation higher than that of
,~ the input shaft, a second driven gear meshing with the first
s drive gear, a second drive gear mounted for rotation coaxially
~; with and relative to the second driven gear and meshing with
the first driven gear, the gear ratios of the gears being such
. that the drive shaft is driven at a rotational speed higher
. . than the input shaft when the second driven gear and the second
drive gear are drivingly connected together, and actuating
~ means operably connected between the second driven gear and the
r~ second drive gear and movable between a first position wherein
s the second driven gear and th~e second drive gear are freely
rotatable relative to each~and a second position wherein a
driving connection is established between the second driven
gear and the second drive gear.
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In one embodiment, the transmission includes a
rotatable counter shaft axially offset from the input
and drive shafts and having an axially extending bore,
the second driven shaft is mounted on the counter shaft
for common rotation therewith, and the second drive
gear is mounted on the counter shaft for rotation
relative thereto. The actuating means includes a
selector shaft carried in the counter bore and is
axially shiftable therein between the first and second
positions, means for drivingly connecting the counter
shaft with the second drive gear when the selector
shaft is shifted to the second position, and means for
selectively shifting the selector shaft between the
first and second positions.
In one embodiment, the transmission includes
an axially extending sleeve member connected to the
second drive gear for common rotation therewith and
surrounding the counter shaft, a plurality of
circumferentially~spa~ed recesses in the inner surface
of the sleeve member, a plurality of
circumferentially-spaced, radially extending passages
in the counter shaft registrable with the recesses, and
a connecting element adapted to drivingly engage a
recess disposed in each of the passages and movable
therein between a retracted position disengaged from
the recesses and an extended position in driving
engagement with recesses. In addition, the selector
shaft is arranged to move the connecting elements to
the extended position in response to movement of the
selector shaft to the second position and to permit the
connecting element to return to the retracted position
in response to movement of the selector shaft to the
first position.
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One of the principal features of the invention
is the provision of marine propulsion device including
an inexpensive, compact overdrive transmission which
can be shifted, after the boat is planing, to provide
higher propeller speed at a lower torque conditions
without increasing engine speed.
Another of the principal features of the
invention is the provision of a simply constructed
overdrive transmission which is particularly adaptable
for a marine propulsion device and can be conveniently
shifted to increase the rotational speed of the output
or drive shaft without increasing the speed of the
input shaft.
Other features, aspects and advantages of the
invention willl become apparent to those skilled in the
art upon reviewing the following detailed description,
the drawing and the appended claims.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a side elevational view of an
outboard motor incorporating various of the features of
the invention.
Fig. 2 is an enlarged, cross sectional view of
the overdrive transmission of the outboard motor shown
in Fig. 1.
Fig. 3 is a view taken generally along line
3-3 in Fig. 2.
Before explaining at least one of the
embodiments of the invention in detail, it is to be
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understood that the invention is not limited in its
application to the details of construction and the
arrangement of component~ set forth in the followlng
description or illustrated in the drawings. The
invention is capable of other embodiments and of being
practiced and carried out in various ways. Also, t is
to be understood that the phraseology and terminology
employed herein is for the purpose of description and
should not be regarded as limiting.
DESCRIPTION OF A PREFERRED El!IBODIMENT
While the invention will be described for use
in an outboard motor, it can be adapted for use in
other marine propulsion devices, such as stern drive
units, and other similar applications.
Illustrated in Fig. 1 is an outboard motor 10
including a power head 12 housing an internal
combustion engine 14 and a lower unit 16 having gear
case 18 which is normally under water. Rotatably
mounted in the gear case 18 is a propeller shaft 20
carrying, on the outer end, a propeller 22. Located
within the gear case 18 is a pair of facing,
axially-spaced bevel gears 24 and 26 which are carried
by and drivingly connectable to the propeller shaft 20.
Extending through the lower unit 16
transversely to the propeller shaft 20 is a rotatably
mounted drive shaft 28 carrying a beveled drive gear 30
which meshes with the gears 24 and 26. The drive shaft
28 is drivingly connected to the engine 14 through an
overdrive transmission designated generally by the
reference numeral 32.
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The transmission 32 includes a power or input
shaft 34 which is rotatably mounted in a housing 35,
via a bearing 36, coaxially with the drive shaft 28 and
which is drivingly connected to the engine 14. The
transmission 32 also includes a first drive gear 38
mounted for common rotation with the input shaft 34 and
a first driven gear 40 which is mounted on a spline
portion 42 of the drive shaft 28 for common rotation
therewith and also mounted for rotation coaxially with
and independently of the input shaft 34.
The input shaft 34 is drivingly connected to
the drive shaft 28 by a one-way, overrunning "sprag"
clutch 44. The clutch 44 is disposed between a clutch
hub 46 which is mounted on a spline portion 48 on the
end of the drive shaft 28 for common rotation with the
drive shaft 28 and a clutch drum 50 which surrounds the
clutch hub 46 in spaced relationship and is mounted for
common rotation with the first drive gear 38. The
clutch 44 permits the input shaft 34 to drive the
driveshaft 28 in one rotary direction and permits the
drive shaft 28 to become free wheeling relative to the
input shaft 34 when the rotational speed of the drive
shaft 28 exceeds the rotational speed of the input
shaft 34 in the same rotary direction, i.e., when the
drive shaft 28 overruns the input shaft 34.
The transmission 32 further includes a counter
shaft 52 which is axially offset from the drive shaft
28 and the input shaft 34 and which is rotatably
journaled in a pair of bearings 54 and 56. A second
driven gear 58 which meshes with the first drive gear
38 is mounted on the counter shaft 52 for common
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rotation therewith. A second drive gear 60 which
meshes with the first driven gear 40 is mounted on the
counter shaft 52 for rotation relative to the counter
` shaft 52 via bearing 62. The gear ratios of the first
drive gear 38, the second driven gear 58, the second
drive gear 60 and the first driven gear 40 are such
that the drive shaft 28 is driven at a rotational speed
greater than that of the input shaft 34 when the second
driven gear 58 and the second drive gear 60 are
drivingly connected together. In the specific
embodiment illustrated, the first drive gear 38 bas a
greater number of gear teeth than the second driven
gear 58.
.~. During normal operation, the input shaft 34
drives the driveshaft 28 at the same rotational speed
as that of the input shaft 34 via the overrunning
asprag~ clutch 44 and the first drive gear 38 rotates
the counter shaft 52 via the second driven gear 58 at a
rotational speed higher than that of the input shaft 34
because the first drive gear 38 has a greater number of
gear teeth than the second driven gear 58. At the same
time, the counter shaft 52 rotates independently of the
second drive gear 60 which is being rotated by the
first driven gear 40.
Actuation means are provided for selectively
drivingly connecting the counter shaft 52 with the
second drive gear 60 so that the drive shaft 28 can be
driven at a rotational speed higher than that of the
input sha~t 34. In the specific embodiment
illustrated, such means includes a longitudinally or
axially extending bore 64 in the counter shaft 52, a
plurality of circumferentially-spaced, radially
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extending bores or passages 66 opening into the axial
bore 64, and a connecting element in the form of a ball
68 disposed in each passage 66. Mounted for common
rotation with the second drive gear 60 and for rotation
relative to the counter shaft 52 via a bearing 69 is a
sleeve member 70 having an inner surface 72 surrounding
and spaced closely adjacent the counter shaft 52. The
inner surface 72 of the sleeve member 70 has a
plurality of circumferentially-spaced indentations or
recesses 74 which are registrable with the counter
shaft passages 66 and are adapted to receive the balls
68. The counter shaft 52 can be drivingly connected to
the second drive gear 60 by displacing the balls 68
radially outwardly into engagement with the recesses 74
of the sleeve member 70.
Means are provided for selectively displacing
the balls 68 into driving engagement with the sleeve member
recesses 74. In the specific embodiment illustrated,
such means includes a plunger or selector shaft 76
carried in the counter shaft bores 66 for relative
axial movement therein. The selectcr shaft 76 has a
reduced end portion 78 and a frusto-conical portion 80
adjacent the reduced end portion 78.
When the selector shaft 76 is in a first or
non-connecting position illustrated in Figs. 2 and 3,
the balls 68 are supported on the reduced end portion
78 of the selector shaft 76 and are retracted inside
the passages 66 out of engagement with the sleeve member
recesses 74. When the selector shaft 76 is shifted
axially (downwardly as viewed in Fig. 2) to a
second or connecting position, the frusto-conical
portion 80 engages the balls 68 and forces them
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radially outwardly into driving engagement w~th the
sleeve member recesses 74.
The selector shaft 76 is shifted between the
non-connecting and connecting positions by reciprocal
pivotal movement of a bell crank 82 pivotally connected
to a link 83 which, in turn, is pivotally connected to
the outer end 84 of the selector shaft 76. Pivotal
movement of the bell crank 82 about its pivot point 85
can be effected by various suitable electromechanical,
mechanical, or hydraulic-actuated means. Thus, the
selector shaft 76 is shifted, in response to counter
clockwise movement of the bell crank 82, from the
nonconnecting position illustrated in Fig. 2 to the
connecting position wherein the frusto-conical portion
80 forces the ball 68 into the sleeve member recesses
74. When this occurs, the drive shaft 28 is driven at a
rotational speed greater than that of the input shaft
34 via a gear train including the first drive gear 38,
the second driven gear 58, the second drive gear 60,
and the first driven gear 40. When the selector shaft
76 is shifted back to the non-connecting position, in
response to clockwise movement of the bell crank 82,
the drive shaft 28 is driven at the same rotational
speed as that of the input shaft 34 via the overrunning
sprag" clutch 44 as described above.
Alternately, the second driven gear 58 can be
mounted for rotation relative to the counter shaft 52
and include the sleeve member 70, the second drive gear
60 mounted for common rotation with the counter shaft
52 and the selector shat 56 arranged to selectively
connect the counter shaft 52 to the second driven gear
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.. Various of the features of the invention are
set forth in the following claims:
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