Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENT`I'ON
(1) Field of the rnv'e'nti'on
The subject Lnventlon relates to a hydraulic steering
assembly to be attached to the tiller arm of an outboard
propulsion unit for a boat so as to rotate the propulsion
unit about a steering axis.
(2~ - Description o the Prior Art
Prior art steering assemblies for outboard propulsion
units of boats have rotated the propulsion unit by means of
push-pull mechanical cables or via hydraulic actuation.
Introduction of higher horsepower engines have resulted in
a demand for more reliable hydraulic steering systems. These
systems have typically included cylinders which protrude an
undesirable amount to one side of the engine. One type of
prior art hydraulic cylinder is mounted in a manner to require
the rod of the cylinder to be secured to the tiller arm of the
engine by means of a link. This assembly is often installed
incorrectly resulting in accidents. Also, it is desirable
to keep the cylinder as short as possible. This has been
accomplished in prior art steering assemblies by including
only one piston rod in the cylinder~ The result is an
imbalance in the oil supply required by the cylinder.
Additional problems have resulted where the steering assem-
blies require specific adaptations of the propulsion unit
to accommodate the assembly. Thus, these assemblies cannot
be adapted for all engine models.
SUMMARY OF THE INVENTIOM
The instant invention provides a propulsion unit
assembly for a boat comprising: a propulsion unit having a
stee~iny axis and a tiller arm extending from said steering
axis; a support structure for removably attaching said
propulsion unit to the boat and defining a tilt axis for said
propulsion unit; and a hydraulic steering assembly for
rotating said propulsion unit about said steering axis
while allowing said propulsion unit to rotate about said tilt
axis of sa;d support structure, said hydraulic steering
assembly including a hydraulic cylinder having two ends and
a hydraulically actuated rod member extending from each of
said ends of said cylinder, securing means disposed on said
cylinder in radially spaced relationship to said rod and
securing said cylinder to said tiller arm of said propulsion
unit for allowing relative rotation therebetween upon movement
of said cylinder along said rod to rotate said propulsion unit
about said steering axis and to move about said tilt axis
with said propulsion unit and said cylinder, and first means
attached to said support structure through said tilt axis
and including a connection to said rod member which is non-
rotatable about the steering axis so that force exerted by
actuation of said hydraulic cylinder through said rod member
and against said first means moves said hydraulic cylinder
along said rod member to rotate said propulsion unit through
its complete steering sweep about said steering axis.
PRIOR ART STATEMENT
Examples of prior art steering systems are U.S. patent
3,654,889 to Bergstedt issued April 11, 1972 and 4,041,889 to
Blanchard issued August 16, 1977. Both patents disclose a
hydraulic steering system including a cylinder and piston
assembly. The assembly actuates turning and/or tilting move-
ment of an outboard propulsion unit. Both patents teach a
system including a rack and pinion steering mechanism. Neither
patent discloses a steering system which is adaptable to most
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outboard propulsion units in production, Also, neither
patent teaches the use of a balanced oil supply within the
cylinder assembly to actuate the housed piston.
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~RIEF ~ESCRIPTION OF THF.~DRAWINGS
Othex advantages of the present invention will be
readily appreciated as the same becomes better understood
by reference to ~he foll~win~ detailed description when
considered in connection with the accompanyin~ drawings
wherein:
FIGUR~ 1 is a diagrammatic plan view of the
steering as~embly of the suhject invention secured to an
outboard prnpulsion unit with the axis o~ rotation on the
tiller arm;
FIGURF. 2 is a ~ida viaw of an outboard propulsion
unit secured to the splash wall of a boat;
FIGURE 3 i~ a plan view partially broken away
and in cross section of the ste~ring assembly secured to
the tiller arm of an outboard propulsion unit with the axis
of rotation hesides the tiller arm;
FIGURE 4 is a cross-sectional view taken along
line 4-4 of FIGURE 3;
FIGURE 5 is a plan view of an alternative
embodiment of the ~ubject steering assembly as it would
be ~ecured to a boat having two outboard propulsion units;
FIGURE 6 is a cross-sectional view taken along
line 6-6 of FIGURE 5 S
FIGURE 7 is a view of the link rod of the pivot
means;
FIGURE 8 is a side view of the clamp member
securing the hydraulic cylinder therewithin;
FIGUP~ 9 is a ~chematic view illustrating
different steering positions of the steerin~ assembl~;
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FIGURE 10 is a view showing alternative attach-
ments and location relative to the tiller arm;
FIGU~ 11 is an enlarged cros~-sectional view of
a sleeve used in the disclosed assembly; and
S FIGURE 12 is an enlarged fragmentary cross-sec-
tional view illustrating an air bleed utilized in the
disclosed assembly.
DESCRIPTION OF PREFERREl~ EMBODIMENT
A hydraulic steering assembly constructed in
accordance with the in~tant invention i5 generally shown
at 10 in FIGURES 1 and 3~ The steering assembly 10 is
secured to a tiller arm 12 of an outboard propulsion unit
14.
The subject hydraulic steering assembly 10
comprises a hydraulia cylinder generally indicated at 18
having a hydraulically actuated rod member 20 extending
therefrom. The hydraulic cylin~er 18 includes securing
means generally indicated at 22 for rotatably securing
the hydraulic cylinder 18 to the tiller arm 12. The se-
curiny means 22 has an axis of rotation at 24 parallel tothe steering axis 16 of the water drive means of the pro-
pulsion unit and i5 attached directly to the tiller arm 12.
FIGURE 2 shows another view of the outboard pro-
pulsion unit 14 as it would be mounted on a boat for
rotation about a steering axis 16.
Returning to FIGURE 1, the steering assen~ly 10
also comprises a pivot means generally indicated at 26
adapted for attachment to the stationary part of the engine
bracket mounted to the boat. The pivot means 26 includes
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a pivotal connection 28 to the rod member 20 to dafine a
pivot axis generally parallel to the steering axis 16 and
nonrotatable about the steering axis 16 so that force
exerted by actuation of the hydraulic cylinder 18 against
the pivot means 26 ro~ates the outboard propulsion unit 14
about the steering axis 16. In other words, the cylinder
18 oscillates with the tiller arm, however, the rod 20 is
stationary in relation to the engine and is not performing
the steerinc3 motion.
As shown in FIGU~E 5, the hydraulic cylinder 18
includes a hydraulic piston 30 slidably supported therein.
The rocl member 20 extends from opposite sides of the piston
30 and through the opposite ends of the hydraulic cylinder
18. The piston 30 is mounted at an equal distance from
the ends of the rod 20. Because the rod extends from the
piston through both ends o~ ~he cylinder, the respective
volumes of fluid enterin~ the cylinder on one side of the
piston 30 and exiting on the other side of the piston 30
are equal during movement of the piston. Hence, there is
a balanced supply and return of hydraulic fluid used at all
times to actuate the piston 30 within the cylinder 18. As
~hown in FIGURE 1, the cylinder 18 can be mounted centrally
in relation to the tiller arm 12 and does not protrude
ex.cessively to either side of the outboard propulsion unit
14.
The cylinder includes a barrel member 32 and two
gland members 34 and 36 secured to the ends thereof. The
gland members 34 and 36 axe threaded to barrel 32 and are
sealed with an appropriate sealing compound. The gland
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members include coupling means or elbows 38 and 40 for con-
veyin~ i~ydraulic fluid. The coupling members 38 and 40
would be connected to hoses leading to a pump driven by a
steering whee] of the steering unit o the boat.
A~ shown in FIGUP~ 12, the cylinder 18 can incluAe
a bleed screw 200 disposed in gland members 34 and 36 for
allowing the release of air from within the cstlinder. rrhe
bleed screw includes a first threaded portion 204 which is
received in the ~hreaded passageway 202. The screw 200 in-
cludes a second threaded portion 206 separated from the
first portion 204 by a portion of reduced diameter 208. ~he
length of the reduced poxtion 208 is greater than the length
of the passageway 202 so that the first threaded portion
204 can be unscrewed to allow bleeding of air. The second
threaded portion 206 can enga~e the passageway 202 so as to
prevent the screw 200 from being completely forced from the
passageway 202 during bleeding. This prevents accidental
loss of the bleed screw duriny bleeding. ~o intentionally
completely remove the bleed scr~ 200, the second threaded
portion 2~6 is threaded out the passageway 202.
The travel distance of the piston 3C within the
cylinder lS is equal or greater than the swing distance of
the outboard propulsion unit 14 (as shown in FIGUl~ 1) about
the steering axis lS at either port or starboard hardover
positions. Therefore, at either hardover position the
stops of the propulsion unit 14 limits the extent of move-
ment of the piston 30 within the cylinder 3~. In other
words, at either hardover posi~ion the steering assembly
uses the stops of the propulsion unit rather than full
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extension of the steering unit at which the piston 30 would
engage an end of the cylinder. In the situation where a
propulsion unit hits an object within the water and is
forced in~o a hardover position, the force exerted is
therefore placed upon the engine stops and not upon the
stops of the ~teering unit, thllsly saving the steering unit
from excessive damage.
As shown in FIGU~S 1 and 2, the pivot means 26
includes attachment means for at~achment through an open-
ing 42 along a tilt axis in a propulsion unit supportstructure 44 which is stationarily attached to the boat
body. The propulsion unit support structure 44 secures the
outboard propulsion unit 14 to the splash wall 46 of a boat~
The opening 42 defines a tilt axis for tilting rotation of
the propulsion unit 14 about the tilt axis. The tilt axis
extend~ transversely to the steering axis defined at 16 and
to the tiller arm 12 so that the propulsion unit may be
rotated into and out of the water about the tilt axis
without changing the relative position of cylinder 18 as
illustrated in FIGURE 2.
As shown in FIGURE 7, the pivot means 2~ includes
an insertion member or link rod having a straight portion
48 for extending through the opening 42 along the tilt axis
and rotatable about the tilt axis to allow rotation of the
insertion member about the tilt axis. ~s shown in FIGURE
1, the pivotal connection 28 is spaced from and in a non-
~ntersecting relationship to the straight portion 48. The
link rod 26 is fixed in the area of the straight portion
48 at the tilt tube center 42 of the tilt tube 45 so that
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the steerin~ is not affected durin~ the trimmin~ movements
of the engine. If ~le link rod 26 with the straight portion
48 is fixed at any other position, the tiller arm 12 would
swing sideward when the engine 14 is trimmed. The insertion
member 26 includes a transverse portion 52 extendin~
batween the straight portion 48 and pivotal connection 28.
The inser~ion member is rotatably secured to the rod
member 20 by bolt 54. Spacer sleeve 56 and collar 57 secure
the propulsion unit support structure therebetweenO Washers
58 are situated between the tilt tube 45 and spacer sleeve
56 and collar 57. In the preferred embodiment the trans-
verse portion 52 of the link rod 26 is separated from the
straight portion 48 by an arcuate portion 50~ The minimum
radius 51 must be about 2.5 times the thickness of the
link rod to avoid excessive local yielding or ruptureO
As shown in ~IGURE 11, ~he spacer sleeve 56 is
a compression fitting and can be made out of nut member 59,
a bushing 57 and a sleeve 61. Member 57 threadedly engages
member 59. In doing so, sleeve 61 is compressed between
~ arcuate portions 63 and 65 and the enclosed link rod
preventin~ the link rod from shiting inside the tilt tube
45. The sleeve 61 can be made from nylon t brass, or the
like.
Preferab~y, the axis of the cylinder 18 is in
the same horizontal plane as the tilt tube axis so that the
cylinder axis remains in the same plane as the tilt axis in
the hardover positions. This is the most mechanically
efficient positioning of the hydraulic cylinder in relation
to the tilt axis.
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FIGU.~E 3 shows the hydraulic cylinder in a
neutral position of actuation. In the pre~erred emhodiMent,
the securing means 22 includes a cylinder plate 62 having
a first edye 64 extendiny in a direction away from the
tiller arm 12 and nonparallel in relation ~o the tiller
arm 12 when the cylindex 18 is in the neutral position as
shown in FIGURE 3. This positioning of the cylinder plate
62 in relation to the tiller arm 12 prevents contact of
the cylinder plate 62 with the tiller arm 12 when ~he steer-
ing assembly is in the starboard hardover position. Inother words, the cylinder plate 62 rotates clockwise about
the axis defined at 24 in steering movement toward the
hardovex starboard position. The cyLinder plate 62 rotates
clockwise about the axis 24 and approaches the tiller arm
12. The angle of the edye 64 of the cylinder plate 62
allows clearance of the tiller arm with the cylinder plate
in the hardover position. Again, this allows the use of
the engine stop in both hardover positions rather than the
steering stops. Therefore, in an overload situation where
the enqine is driven into a hardover posîtion the con-
struction of the cylinder plate 62 is adapted to prevent
damage to the steeriny assembly.
The securing means generally indicated at 22
also includes a tiller plate 66 adapted for fixed attach-
ment to the tiller arm 12. Bolt 68 interconnects thecylinder plate 62 and tiller plate 66 for rotation
relative to one another about the axis of rotation defined
~t 24.
As shown in FIGURE 3, the tiller plate 66 in-
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cludes at least two holes 70 and 72 for receiving fasten-
ing means 74 and 76 for attachment to the tiller a~n 12.
Aq shown in cross section in FIGURE 4~ the cylinder plate
62 is rotatably secured -to the tiller plate 66 by bolt
68. The cylinder plate 62 is secured on the same side
of the tiller plate 66 as the tiller arm 12 but may be
reversed as illustrated in FIGU~E 6.
As illustrated in FIGU~E 3, the hole 70 in the
tiller plate 66 is elongated, i.e., a slot or oval. The
elongated hole 70 allows the tiller plate to be secured on
either side of the tiller arm 12 to move the plate a
distance equal to the differences hetween the location of
tiller arms in relation to tilt axes of presently manufac-
tured outboard propulsion units.
As shown in FIGU~E 10, in order to maintain the
proper steering geometry, the tiller plate 66 is in position
67 when the plate is mounted above or ~elow the tiller arm
12 or the tiller plate 66 is in position 69 when it is
mounted above or below the tiller arm. The varyinq position-
ing of bolt hole 71 allows the cylinder assembly to he
mounted almost parallel to the tilt tube 45 in accordance
with the ~pecifications of all motors so that the forces
created by cylinder 18 act perpendicularly on tiller arm 12.
Also, the use of the face-to-face connection of the tiller
plate and cylinder plate as a securing means for the
cylinder 18 to the tiller arm 12 provides ma~imal support
for the steering assembly.
FIGURE S shows an additional embodiment of the
su~ject assembly including a second tiller plate 78
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adapted for attacllment to a second tiller arm 80 of a
second outboard propulsion unit. An alternative configu-
ration o the tiller plate is shown at 77. In this embod-
~lent the tiller plate 77 is shown ~o he mounted on the
tiller arm 12. This arrangement is also shown in cross
section in FIGURE 6. Again, cylinder plate 62 and tiller
ann 12 are mounted on the same side of the tiller plate 77.
Coupling means directly couples the tiller plates 77 and
78 together for coordinating steering movement between the
two outboarcl propul~sion units whereby the foxces are trans-
ferred directly ~etween the tiller arms. The coupling
means includes a tie rod 86. The tiller plates 77 and 78
have bores therein for receiving bol~ means 90 for
rotatably supporting spherical rod ends 100 o the tie
rod 86. Forces resulting from movement of the propulsion
units are therefore transferred directly between the plates
77 and 78. Therefore, these steering forces are transferred
directly between the tiller arms 12 and 80 and not to the
cylinder 18. The result is that the steering assembly only
encounters steering forces which equal the difference
between the forces exerted on each propulsion unit. In
other words, one propulsion unit may have a negative steer-
ing force while the other has a plus steering force. Thus,
the steering load exerted on the steering assembly is the
5 difference of loads between the port and starboard engines.
As shown in FIGU~E 5, the cylinder includes a
~econd edge spaced from the first edge 64 which includes
a notch 104 therein for allowing clearance of the spherical
rod end 100 which secures the tie rod 86 to the tiller plate
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77. This adaptation allows for clearance of the spherical
rod end 100 by the cylinder plate 62 when the steering
assembly is in the hardover port position. ~gain, this
increases the rotational distance of the steerin~ assembly
which allows the assembly to use the engine stops rather
than the steeriny assembly stops.
As shown in FIGURES 4 and 6, the securing means
includes a bushing 106 having a bore therethrough for
receiving the bolt 68. The bushing 106 includes a collar
portion 108 and the cylinder plate 62 receives the ou~er
diameter of the collar 108 with the cylindrical length
longer than the thickness of cylinder plate 62. Therefore,
the cylinder plate 62 is rotatably secured between the
bushing 106 and the tiller plate 77 for rotation there-
between about the axis of rota~ion.
FIGUR~ 8 shows the cylinder plate 62 secured to
the cylinder 18 via clamp member 110. The clamp member
110 is of a C-shaped construction having the irst and
second legs or clampin~ portions 112 and 114 respectively.
The legs have two bores 119 therethrough for receiving
fastening means in the form of the cl~mping bolts 116. The
bolts 116 are threaded to the clampiny portion 114 and the
bore 119 is countersunk to receive the heads of the bolts
116.
The first leg 112 of the C-shaped construction
includes a flat surface 118 having four threaded bores 120
therein. The cylinder plate 62 has hores therein corre-
sponding to the hores 120 in the first leg 112 ~or receiv~
ing bolts 124 ~7hich fixedly secure the cylinder plate 62
12
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P-5~9
to the C-shaped construction 110.
FIGURE 9 is a diagrammatic or schematic drawing
of the steering assembly 19 shown in various positions
relative to the steering axis 16 and the pivot axis 28.
Position A ~hows the hardover port steering position.
Position B is the strai~htorward position. Position C is
the hardover starboard position. For maximum eEficiency
xhe pivot axis 28 should stay as close as possible on line
X-Z which goes through the hardovex position A and C. The
Y dimension has to realize the tiller arm radius dimension
R, the clamp member dimension D and the maximum steering
travel dimension T. Dimension Y should be as long as
possible to make the deflection angle alpha as small as
possible.
The invention has been described in an illustra-
tive manner and it is to be understood that the terminology
which has been used is intended to be in the nature of
words of description rather than of limitation.
Obviously~ many modifications and variations of
the present invention are po~sible in light o the above
teachings. It is, therefore, to be understood that within
the scope of the appended claims, the invention may be
practiced otherwise than as specifically described.
