U.S. patent number RE38,851 [Application Number 10/227,439] was granted by the patent office on 2005-10-25 for shock absorbing arrangement for marine outboard drive.
This patent grant is currently assigned to Yamaha Marine Kabushiki Kaisha. Invention is credited to Daisuke Nakamura.
United States Patent |
RE38,851 |
Nakamura |
October 25, 2005 |
**Please see images for:
( Certificate of Correction ) ** |
Shock absorbing arrangement for marine outboard drive
Abstract
A shock absorbing arrangement integrates in a compact manner
into a fluid motor of a tilt cylinder, and consequently is
particularly well suited for a small outboard drive that may only
have a slimed tilt cylinder. The shock absorbing arrangement is
provided in a piston for permitting flow from the first chamber to
the second chamber upon the application of a predetermined force
tending to cause the outboard drive to tilt-up. The shock-absorbing
mechanism comprises a check valve assembly accommodated in a hollow
space that is formed in the piston and is closed by a plug attached
to the piston. A piston rod extends through the first chamber from
the piston and is separately formed with the piston. The piston rod
includes a passage that communicates with the hollow formed in the
piston. A diameter of the passage provided in the piston rod is
larger than the diameter of a valve seat for the check valve
assembly in order to reduce fluid friction loss across the
shock-absorbing valve assembly.
Inventors: |
Nakamura; Daisuke (Hamamatsu,
JP) |
Assignee: |
Yamaha Marine Kabushiki Kaisha
(Shizuoka, JP)
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Family
ID: |
12665306 |
Appl.
No.: |
10/227,439 |
Filed: |
August 22, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
257613 |
Feb 25, 1999 |
06106343 |
Aug 22, 2000 |
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Foreign Application Priority Data
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Feb 25, 1998 [JP] |
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10-043495 |
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Current U.S.
Class: |
440/61R;
440/53 |
Current CPC
Class: |
B63H
20/10 (20130101); F15B 15/1447 (20130101); F15B
15/149 (20130101); F05C 2251/042 (20130101) |
Current International
Class: |
B63H
20/10 (20060101); B63H 20/00 (20060101); B63H
020/10 () |
Field of
Search: |
;440/61R,61T,56,53 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sotelo; Jesus D.
Attorney, Agent or Firm: Knobbe, Martens, Olson & Bear,
LLP
Claims
What is claimed is:
1. A positioning mechanism for an outboard drive supported for
tilting movement relative to a hull of an associated watercraft
about a substantially horizontally disposed tilt axis, the
positioning mechanism comprising a fluid motor assembly having a
cylinder, a piston slidably supported in the cylinder and defining
first and second chambers, a piston rod extending from the piston
through one of the chambers, and a shock-absorbing mechanism
arranged to permit fluid .Iadd.to .Iaddend.flow from the first
chamber to the second chamber upon the application of a preset
force tending to cause the outboard drive to tilt up about the tilt
axis, the shock-absorbing mechanism including a check valve
assembly principally accommodated in a hollow that is formed in the
piston and is closed with a plug attached to the piston.
2. The positioning mechanism as set forth in claim 1, wherein the
check valve assembly is substantially aligned with the axis of the
piston rod.
3. The positioning mechanism as set forth in claim 1, wherein the
.[.damping.]. .Iadd.shock-absorbing .Iaddend.mechanism further
comprises a passage connecting the first chamber and the hollow,
and the check valve assembly comprises a valve seat located between
the passage and the hollow.
4. The positioning mechanism as set forth in claim 3, wherein the
passage has a larger diameter than the diameter of the valve
seat.
5. The positioning mechanism as set forth in claim 4, wherein the
piston rod and the piston are formed separately, and at least a
part of the passage passes through a portion of the piston rod.
6. The positioning mechanism as set forth in claim 3, wherein the
check valve assembly comprises a ball disposed within the hollow
and a retainer for retaining the ball, and a spring for urging the
retainer toward the valve seat, the spring being arranged between
the retainer and the plug.
7. The positioning mechanism as set forth in claim 1, wherein the
.[.damping.]. .Iadd.shock-absorbing .Iaddend.mechanism further
comprises a passage passing through the piston rod and opening to
the first chamber.
8. The positioning mechanism as set forth in claim 1, wherein the
.[.damping.]. .Iadd.shock-absorbing .Iaddend.mechanism further
comprises a passage passing through the piston and opening to the
first chamber.
9. The positioning mechanism as set forth in claim 1, wherein the
.[.damping.]. .Iadd.shock-absorbing .Iaddend.mechanism further
comprises a passage passing through the piston and opening to the
second chamber.
10. The positioning mechanism as set forth in claim 1, wherein the
piston rod is formed separately with the piston and the piston has
a recess mating with an end portion of the piston rod, and the
piston rod and the piston being jointed with each other so that the
piston rod is affixed to the piston.
11. The positioning mechanism as set forth in claim 9, wherein the
piston rod has a male threaded end and the piston has a female
threaded recess.
12. The positioning mechanism as set forth in claim 1, wherein the
second chamber has a free piston.
13. The positioning mechanism as set forth in claim 1, wherein the
piston includes at least one return check valve for returning fluid
from the first chamber to the second chamber after pop-up.
14. A positioning mechanism for an outboard drive supported for
tilting movement relative to a hull of an associated watercraft
about a substantially horizontally disposed tilt axis, the
positioning mechanism comprising a fluid motor assembly having a
cylinder, a piston slidably supported in the cylinder and defining
first and second chambers, a piston rod .[.being formed separately
from the piston and affixed to the piston, the piston rod.].
extending from the piston through one of the chambers, and a shock
absorbing mechanism that permits fluid flow from the first chamber
to the second chamber upon the application of a preset force
tending to cause the outboard drive to tilt up about the tilt axis,
the shock-absorbing mechanism including a passage connecting the
first chamber and to a hollow formed in the piston, and a check
valve assembly principally accommodated in the hollow, the check
valve assembly including a valve seat that is located between the
hollow and the passage and that has a smaller cross-sectional flow
area than a cross-sectional flow area of the passage.
15. The positioning mechanism as set forth in claim 14, wherein at
least a part of the passage passes through the piston rod.
16. A positioning mechanism as set forth in claim 14, wherein the
valve assembly additionally comprises a ball disposed in the hollow
and is positioned against the valve seat, a retainer, and a spring
arranged to urge the retainer toward the valve seat with the
retainer acting against the valve.
17. In an outboard drive supported for tilting movement relative to
a hull of an associated watercraft about a substantially
horizontally disposed tilt axis, a positioning mechanism comprising
a fluid motor including a cylinder, a piston slidably supported in
the cylinder and defining first and second chambers, a piston rod
extending from the piston through one of the chambers, and means
for allowing the drive unit to pop-up when an underwater obstacle
is struck by the outboard drive, the pop-up allowing means
including a check valve assembly accommodated in a hollow being
formed in the piston and closed with a plug attached to the
piston..Iadd.
18. The positioning mechanism as set forth in claim 1, wherein the
piston rod extends generally vertically through the first chamber,
a portion of the piston rod extends out of the first chamber larger
when the fluid flows to the second chamber from the first chamber
than when the fluid flows to the first chamber from the second
chamber..Iaddend..Iadd.
19. The positioning mechanism as set forth in claim 14, wherein the
piston rod extends generally vertically through the first chamber,
a portion of the piston rod extends out of the first chamber larger
when the fluid flows to the second chamber from the first chamber
than when the fluid flows to the first chamber from the second
chamber..Iaddend..Iadd.
20. The positioning mechanism as set forth in claim 19 additionally
comprising a return valve arranged at the piston, the return valve
allowing the fluid in the second chamber to return to the first
chamber..Iaddend..Iadd.
21. The positioning mechanism as set forth in claim 20, wherein a
size of the return valve is smaller than a size of the check valve
assembly..Iaddend..Iadd.
22. The positioning mechanism as set forth in claim 14, wherein the
piston rod is formed separately from the piston and is affixed to
the piston..Iaddend..Iadd.
23. The positioning mechanism as set forth in claim 17, wherein the
piston rod extends generally vertically through the first chamber,
a portion of the piston rod extends out of the first chamber larger
when the fluid flows to the second chamber from the first chamber
than when the fluid flows to the first chamber from the second
chamber..Iaddend..Iadd.
24. An outboard drive for a watercraft comprising a housing unit, a
bracket assembly arranged to support the housing unit to the
watercraft for pivotal movement about a generally horizontally
extending tilt axis, and a fluid motor arranged to pivotally move
the housing unit relative to the watercraft about the tilt axis,
the fluid motor comprising a cylinder defining an internal cavity,
a piston slidably supported within the cavity, the piston dividing
the cavity into first and second chambers, a piston rod extending
from the piston generally vertically through the first chamber, and
a damping mechanism configured to allow fluid in the first chamber
to flow toward the second chamber upon the application of a preset
force tending to cause the housing unit to pivot about the tilt
axis, the damping mechanism comprising a shock absorbing valve
disposed in a hollow defined at the piston, the hollow being closed
by a plug..Iaddend..Iadd.
25. The outboard drive as set forth in claim 24, wherein the hollow
communicates with the second chamber..Iaddend..Iadd.
26. The outboard drive as set forth in claim 25, wherein the piston
additionally defining a flow path communicating with the first
chamber and the hollow..Iaddend..Iadd.
27. The outboard drive as set forth in claim 24 additionally
comprising a return valve arranged at the piston, the return valve
allowing the fluid in the second chamber to return to the first
chamber..Iaddend..Iadd.
28. The outboard drive as set forth in claim 27, wherein a size of
the return valve is smaller than a size of the shock absorbing
valve..Iaddend..Iadd.
29. The outboard drive as set forth in claim 28, wherein the size
of the return valve is less than a third of the size of the shock
absorbing valve..Iaddend..Iadd.
30. The outboard drive as set forth in claim 28 additionally
comprising a second piston slidably supported within the second
chamber..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a shock absorbing arrangement for a
marine outboard drive and more particularly to a shock absorbing
arrangement for a compact tilt adjustment system that is
particularly well suited for small outboard drive.
2. Description of Related Art
In a wide variety of outboard drives, both outboard motors and the
outboard drive section of and inboard/outboard drive, a hydraulic
tilt adjustment mechanism supports the outboard drive for tilting
movement relative to a hull of an associated watercraft about a
substantially horizontally disposed tilt axis. The tilt adjustment
mechanism generally has a shock absorbing arrangement in case the
outboard drive strikes an underwater obstacle so as to protect the
drive from being seriously damaged.
FIGS. 1 and 2 illustrate an exemplary fluid motor assembly with a
shock absorbing arrangement of a conventional tilt adjustment
mechanism. FIG. 2 is a cross-sectional view taken along the line
2--2 in FIG. 1.
The fluid motor assembly, indicated generally by the reference
numeral 1 in FIGS. 1 and 2, has a cylinder 2. The lower end 3 of
the cylinder 2 is connected to a clamping bracket (not shown) that
is affixed to an associated watercraft. The clamping bracket
supports a swivel bracket (not shown) for pivotal movement about a
horizontally disposed axis. A plug 4 is provided for closing the
upper end of the cylinder 2. The cylinder 2 slidably supports a
piston 5 that defines an upper chamber 6 and a lower chamber 7. A
piston rod 8 is affixed to the piston 5 with a bolt 9 and the rod 8
extends through the upper chamber 6 outwardly through the plug 4. A
washer 10 is interposed between the piston 5 and the bolt 9. The
washer has a flange portion 11 that acts as a seat for a check
valve assembly described later.
An upper end 12 of the piston rod 8 is connected to a swivel
bracket that supports a drive unit (not shown) for pivotal movement
about a vertically disposed axis. An opening 13 is provided at the
upper portion of the cylinder 2 that is immediately below the plug
4, and then through the upper chamber 6 is connected to a fluid
supply and control system (not shown). Meanwhile, another opening
14 is provided at the lower portion of the cylinder 2 that is
immediately above the lower end 3 and thereby the lower chamber 7
is connected to the fluid supply and control system also. In other
words, the upper chamber 6 and the lower chamber 7 are connected
with each other through the fluid supply and control system. The
hydraulic assembly 1 is filled with a hydraulic fluid. This
hydraulic fluid is moved from the upper chamber 6 to the lower
chamber 7 or vice versa by the fluid supply and control system and
hence the piston rod 8 may extend until the piston 5 contacts the
plug 4 and retract until the piston 5 contacts the lower end 4. By
these movements, the outboard drive is tilted up or tilted
down.
The piston 5 has a plurality of hollows 15 that are disposed at the
periphery of the piston 5 at even intervals. These hollows 15 open
to the lower chamber 7. The individual hollows 15 are also
connected to the upper chamber 6 through apertures or passages 16.
The arrangement of these apertures 16 is best seen in FIG. 2. A
plurality of check valve assembly assemblies 17 are accommodated in
the individual hollows 15. The check valve assembly 17 consists of
a ball 18, a retainer 19 and a spring 20. The ball 18 is seated at
a valve seat 21 formed at an upper end of the respective hollow 15.
The diameter of the ball 15 is larger than the diameter of the
valve seat 21. The spring 20 is placed between the retainer 19 that
retains the ball 15 and the flange portion 11 of the washer 10 so
that the ball 18 is urged against the valve seat 21 to close off
fluid flow through the respective check valve assembly between the
upper chamber 6 and the lower chamber 7.
When an underwater obstacle, such as a drift wood or a rock, is
struck by the drive unit with sufficient force, the piston rod 8
will exert sufficient force on the piston 5 so as to overcome the
action of the check valve assemblies 17. That is, the sufficient
force on the piston 5 moves each ball 18 to an open position
against the bias of the corresponding spring 20. Thus, the fluid in
the upper chamber 6 can flow into the lower chamber 7 through the
aperture 16 and the hollow 15. The flow of the fluid from the upper
chamber 6 to the lower chamber 7 permits the piston 5 to move
upwardly as indicated with the arrow 22 and, thus, allows the drive
unit to pop up.
As described above and seen in FIGS. 1 and 2, the plurality of
check valve assemblies 17 are provided at the periphery of the
piston 5 so as to surround the connecting bolt 9. A relatively
small outboard drive, however, can accommodate only a slim
cylinder. Such a slim cylinder has a smaller diameter piston that
often does not have enough space to accommodate the check valve
assemblies around a connecting bolt. Because a piston rod should
have almost the same thickness as that in a larger outboard drive
for keeping its stiffness, little space exists to accommodate such
value assemblies on a smaller diameter piston.
One shock absorbing arrangement that may resolve the problem noted
above is disclosed in the U.S. Pat. No. 5,262,843. The construction
of this cylinder, however, is complicated and thus costly to
produce.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide a shock absorbing
arrangement that is particularly suitable to a slimed cylinder for
a relatively small outboard drive. Another aspect of the invention
involves a shock absorbing arrangement that allows easy machining
and assembling of members. In a preferred form, the invention is
adapted to be embodied in an outboard drive that is supported for
tilting movement relative to a hull of an associated watercraft
about a substantially horizontally disposed tilt axis.
In accordance with one mode of this invention, a shock absorbing
arrangement is provided for a tilt adjustment mechanism. The tilt
adjustment mechanism comprises a fluid motor assembly that includes
a cylinder. A piston is slidably supported in the cylinder and the
piston defines first and second chambers. A piston rod extends from
the piston through one of the chambers. The shock absorbing
mechanism is provided for permitting fluid flow from the first
chamber to the second chamber upon the application of a preset
force tending to cause the drive unit to tilt up about a tilt axis.
The shock-absorbing mechanism includes a check valve assembly
accommodated in a hollow that is formed at least in part in the
piston and is closed by a plug attached to the piston.
In accordance with anther aspect of this invention, a trim
adjustment mechanism comprises a fluid motor assembly that includes
a cylinder. A piston is slidably supported in the cylinder and
defines first and second chambers. A piston rod is formed
separately from the piston and is affixed to the piston in a manner
extending through one of the chambers. A shock-absorbing mechanism
is provided to permit fluid flow from the first chamber to the
second chamber upon the application of a preset force tending to
cause the drive unit to tilt up about a tilt axis. The shock
absorbing mechanism includes a passage connecting the first chamber
and to a hollow or another passage formed in the piston, and a
check valve assembly that is principally accommodated in the
hollow. The check valve assembly includes a valve seat that is
located between the hollow and the passage and that has a smaller
cross-sectional flow area than a cross-sectional flow area of the
passage.
Further aspects, features and advantages of this invention will
become apparent from the detailed description of the preferred
embodiments which follow.
BRIEF DESCRIPTION OF THE DRAWINGS
As noted above, FIGS. 1 and 2 illustrate an exemplary shock
absorbing arrangement employed with a conventional tilt adjustment
mechanism. FIG. 2 is a cross-sectional view taken along the line
2--2 in FIG. 1. These figures are provided in order to assist the
reader's understanding of the conventional shock absorbing
arrangement and for the reader to better appreciate the aspects,
features and advantages associated with the present invention.
FIGS. 3 and 4 illustrate a relatively large outboard motor and a
tilt and trim adjustment mechanism in which a present shock
absorbing arrangement can be provided. FIGS. 5 and 6, however,
illustrate a smaller outboard motor and a tilt adjustment mechanism
in which the present shock absorbing arrangement is particularly
well suited. FIG. 7 to 11 illustrate preferred embodiments of the
present shock absorbing arrangement in detail. These figures of
preferred embodiments are intended only to illustrate the
invention, and not to limit it. The following further describes
these figures of the embodiments.
FIG. 3 is a partial side elevational view showing an outboard motor
attached to the transom of a watercraft (shown partially and in
section) including a tilt and trim adjustment system.
FIG. 4 is an enlarged rear elevational view of the tilt and trim
adjustment mechanism of FIG. 3.
FIG. 5 is a side elevational view showing a simplified tilt
adjustment mechanism that is particularly suitable for a small
outboard drive, with portions of a swivel bracket assembly shown in
section.
FIG. 6 is a front elevational view of the tilt adjustment mechanism
of FIG. 5.
FIG. 7 is a cross sectional view showing a cylinder of either the
tilt and trim adjustment mechanism of FIGS. 3 and 4, or the tilt
adjustment system of FIGS. 5 and 6, with the cylinder including a
shock absorbing arrangement configured in accordance with a
preferred embodiment of the present invention.
FIG. 8 is an enlarged partial cross sectional view showing the
shock absorbing arrangement of FIG. 7.
FIG. 9 is a schematic diagram showing a fluid circuit for a
hydraulic system that can be used with the tilt adjustment system
of FIGS. 5 and 6 or the tilt and trim adjustment mechanism of FIGS.
3 and 4.
FIG. 10 is an enlarged partial cross sectional view showing a shock
absorbing arrangement configured in accordance with another
embodiment of the present invention.
FIG. 11 is a schematic diagram showing another fluid circuit for
the hydraulic system that can be used with the tilt and trim
adjustment system of FIGS. 3 and 4, as well as the tilt adjustment
system of FIGS. 5 and 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
With reference initially to FIGS. 3 and 4, the general environment
in which the invention may be practiced is illustrated. An outboard
motor, indicated generally by the reference numeral 31, comprises
the outboard drive in this embodiment. The term "outboard drive" is
utilized to describe either an outboard motor or the outboard drive
portion of an inboard/outboard drive. In addition, as further
appreciated from the description below, the present shock-absorbing
arrangement can be used with a tilt and trim adjustment system,
such as that depicted in FIGS. 3 and 4, which include both trim
cylinders and a tilt cylinder, with a tilt adjustment system, such
as that depicted in FIGS. 5 and 6, which includes a single cylinder
to effect both tilt and trim movement of the outboard drive, and
with other types of outboard drive positioning system utilizing one
or more fluid motor.
The outboard motor 31 includes a power head 32 and a drive shaft
housing 33 that depends from the power head 32. A lower unit 34 is
provided at the lower end of the drive shaft housing 33 and
supports the propeller 35. The power head 32 accommodates a
combustion engine 36 therein and the drive shaft housing 33
contains a drive shaft 37 that extends from the engine 36 to a
bevel gear 38 in the lower unit 34. The bevel gear 38 transmits
power from the engine 36 to the propeller 35 through a propeller
shaft 39. In this manner, the engine 36 drives the propeller 35 (or
another type of propulsion device).
A steering shaft (not shown) is fixed in a known manner to the
drive shaft housing 33 and is journaled for steering movement about
a generally vertically extending axis within a swivel bracket 40.
The swivel bracket 40, in turn, is pivotally connected by means of
a pivot pin 41 to a clamping bracket 42. The pivot pin 41 permits
tilting movement of the outboard drive 31 about the horizontally
disposed axis defined by the pivot pin 41 for either trim
adjustment or for tilt-up and pop-up of the outboard drive 31. The
clamping bracket 42 is affixed to a transom 43 of a watercraft 44
in a known manner.
A tilt and trim adjustment mechanism operates generally between the
outboard motor 31 and the transom 43 to effect tilt and trim
movement. The tilt and trim adjustment mechanism more specifically
operates between the clamping bracket 42 and the swivel bracket 40.
In the illustrated embodiment, the tilt and trim adjustment
mechanism includes a tilt cylinder assembly 45 and a trim cylinder
assembly 46. Tilting movement of the outboard drive 31 is
controlled primarily by means of the tilt cylinder assembly 45
while the trim condition of the outboard drive 31 is controlled
primarily by means of the trim cylinder assembly 46. The tilt and
trim adjustment mechanism, however, can include a cylinder assembly
that effects movement of the outboard motor both through a trim
range of movement and to a fully tilted up position, as illustrated
in FIGS. 5 and 6.
The tilt cylinder assembly 45 and trim cylinder assembly 46 are
both fluid motors that are powered by pressurized working fluid
delivered by a fluid pump 47 (see FIG. 4). The pump 47 is driven by
a reversible electric motor (not shown) in a known manner. A fluid
reservoir 48 communicates with the fluid pump 47. The structure of
the outboard drive 31 and its tilt and trim arrangement as thus far
described may be considered to be conventional.
The tilt cylinder assembly 45 includes a cylinder housing 49 that
is formed with a trunnion 50. The trunnion 50 is pivotally
connected to the clamping bracket 42 by means of a pivot pin 51.
The cylinder housing 49 is divided into a pair of fluid chambers by
a piston to which a piston rod 52 is connected. The piston rod 52
extends through the upper end of the cylinder housing 49 and has,
affixed to it, a connecting member 53. The connecting member 53 is
pivotally connected to the swivel bracket 40 by means of a pivot
pin 54. It should be readily apparent, therefore, that extension
and retraction of the piston rod 52 will effect pivotal movement of
the swivel bracket 40 relative to the clamping bracket 42 for
pivoting the outboard drive 31 about the pivot pin 41. The tilt
cylinder assembly 45 is a high speed, low force fluid motor and is
normally employed for pivoting the outboard drive 31 from a trim up
condition to a tilted up out of the water condition.
A shock absorbing arrangement is incorporated in the tilt cylinder
assembly 45 for a pup-up movement of the outboard drive 31. The
shock absorbing arrangement will be described later in detail.
The trim cylinder assembly 46 is affixed to a clamping bracket 42.
The trim cylinder assembly 46 includes a pair of cylinder housings
56 that are disposed on either side of the tilt cylinder assembly
55. Like the tilt cylinder 49, the trim cylinder housing 56 is
divided into an upper and lower section by a piston. The trim
cylinder housing 56, however, is rigidly affixed to the clamping
bracket 42. A piston rod 57 is rigidly affixed to the piston of the
trim cylinder assembly 55. This trim piston rod 57 normally bears
directly against the swivel bracket 40 for effecting its pivotal
movement. The piston rod 57 reciprocates along a fixed axis while
the swivel bracket 40 pivots about the pivot pin 41. The swivel
bracket has a thrust taking member 58. The top end of the piston
rod 57 contacts the thrust taking member 58. Accordingly, extension
and retraction of the piston rod 57 will effect pivotal movement of
the swivel bracket 40 also relative to the clamping bracket 42 for
pivoting the outboard drive 31 about the pivot pin 41 within a trim
range of movement.
Another outboard drive 61 is shown in FIGS. 5 and 6 and includes a
tilt adjustment mechanism. This outboard drive 61 is smaller than
the outboard drive 31 described above, has no trim adjustment
device, and includes a single slim cylinder to effect tilt and trim
movement of the outboard drive 61. The present shock absorbing
arrangement is particularly well suited for this type of outboard
drive 61, but not limited to it.
A steering shaft 62 is fixed to the drive shaft housing 63 with an
upper mount assembly 64 and a lower mount assembly 65, and is
journaled for steering movement about a generally vertically
extending axis within a swivel bracket 66. The swivel bracket 66,
in turn, is pivotally connected by means of a pivot pin 67 to a
clamping bracket 68. The pivot pin 67 permits tilting movement of
the outboard drive 61 about the horizontally axis defined by the
pivot pin 67 for tilt-up and pop-up operation of the outboard drive
61. The clamping bracket 68 is affixed to the transom 43 of the
watercraft 44, in a fashion similar to that noted above in
connection with the outboard drive 31.
A tilt cylinder assembly 70 is a fluid motor and is provided for
tilt adjustment operation and also for the pop-up movement of the
outboard drive 61. The tilt cylinder assembly 70 includes a
cylinder housing 71. The lower end of the cylinder housing 71 is
pivotally connected to the clamping bracket 68 by means of a pivot
pin 72. The cylinder housing 71 is divided into a pair of chambers
by a piston to which a piston rod 73 is connected. The piston rod
73 extends through the upper end of the cylinder housing 71 and is
pivotally connected to the swivel bracket 66 by means of a pivot
pin 74.
The tilt cylinder assembly 70 is powered by pressurized working
fluid delivered by a fluid pump 75. The pump 75 is driven by a
reversible electric motor 76. A switch valve 77 is provided for
switching flows of the working fluid between the chambers in tilt
operations.
Because the tilt operation of this cylinder assembly 70 is
essentially similar to that of the tilt cylinder assembly 45, no
further description is believed necessary for an understanding and
appreciation of the invention. It therefore should be apparent that
the present shock-absorbing mechanism can be used with, but not
limited solely to, both types of outboard drive positioning systems
described above. The following description thus uses the
corresponding reference numerals to illustrate further this aspect
of the invention; the first reference numeral relates to the
corresponding component of the tilt and trim adjustment mechanism
of FIGS. 3 and 4, while the second reference numeral, which is
placed in parentheses, relates to the corresponding component of
the tilt adjustment mechanism of FIGS. 5 and 6.
With reference now to FIGS. 7, 8 and 9, a preferred embodiment of
the present shock absorbing arrangement will be described in
detail.
The hydraulic tilt assembly 45 (70), the cylinder 49 (71) and the
piston rod 52 (73) have been described above. Also, the lower end
80 (trunnion 50 in FIG. 3) of the cylinder 49 (71) is connected to
the clamping bracket 42 (68), while the upper end 81 (connecting
member 53 in FIG. 3) is connected to the swivel bracket 40 (66) as
described above. It is understood, however, that the orientation of
the cylinder 49 (71) can be reversed so as to be fixed to the
swivel bracket 40 (71) with the piston rod 52 (73) connected to the
clamping bracket 42 (68), in which case, the following
descriptional terms related to orientation, such as, for example,
"upper" and "lower," would be reversed.
The cylinder 49 (71) slidably supports a piston 82 that defines an
upper chamber 83 and a lower chamber 84. The piston rod 52 (73) is
affixed to the piston 82, but preferably these components are
separately formed and coupled together. In the illustrated
embodiment, the piston rod 52 (73) has a male threaded end 85 and
the piston 82 has a female threaded recess 86, and both of the male
threaded end 85 and the female threaded recess 86 are jointed by
screwing the male end 85 into the female recess 86. A periphery
about the recess 86 in the piston 82 forms a bulge 87 so that the
threaded area is elongated.
A plug 88 closes the top end of the cylinder 49. The piston rod 52
(73) extends through the upper chamber 83 and outwardly through the
plug 88.
An opening 89 is provided at the upper portion of the cylinder 49
(71) at a position immediately below the plug 88. The opening 89
connects the upper chamber 83 to a fluid supply and control system
which, as understood from FIG. 9, includes the fluid pump 47 (75),
the fluid reservoir 48 and the switch valve 77. Meanwhile, another
opening 90 is provided at the lower portion of the cylinder 49 (71)
at a position immediately above the lower end 80 and thereby the
lower chamber 84 is connected to the fluid supply and control
system also. In other words, the upper chamber 83 and the lower
chamber 84 are connected with each other through the fluid supply
and control system. The hydraulic assembly 45 (70) is filled with a
hydraulic fluid. This hydraulic fluid is moved from the upper
chamber 83 to the lower chamber 84 or vice versa by the fluid
supply and control system and hence the piston rod 52 (73) can
extend until the piston 82 contacts the plug 88 and retract until
the piston 82 contacts the lower end 80. By these movements, the
outboard drive is tilted up or tilted down.
The piston 82 has a hollow 91 immediately under the lower end 85 of
the piston rod 52 (73). In the illustrated embodiment, the hollow
91 has a generally cylindrical shape, is aligned with the axis of
the piston rod 52 (73), and is placed within a projected area of
the piston rod 52 (73); that is, within a cylindrical space in the
piston 82 directly below the piston rod 52 (73) defined by
imaginably continuing the piston rod 52 (73) through the piston 82.
The hollow 91 is connected to the upper side of the piston 82
through a passage 92. An inner end of the hollow 91, i.e., the
portion where passage 92 opens to the hollow 91, forms a valve seat
93 for a check valve assembly described later. The lower end 85 of
the piston rod 52 (73), in turn, includes a passage 94 that is
aligned with the axis of the piston rod 52 (73). The passage 94
opens to the upper chamber 83 through a pair of apertures (branch
passages) 95, 96. The other end of the passage 94 opens to the end
of the piston rod 52 (73) and hence into the passage 92 in the
piston 82 such that the passage 94 in the piston rod 52 (73) and
the passage 92 in the piston together form a passageway between the
valve seat 93 and the upper chamber 83. The diameter of the passage
94 is larger than the passage 92, i.e., valve seat 93. And while
the passage 92 has generally a uniform diameter in the illustrated
embodiment, it is understood that the smallest diameter or
cross-sectional flow area of the passage 92 desirably is larger
than the diameter of the valve seat 93. A larger diameter passage
94 can be formed in the piston rod 52 (73) because the rod 52 (73)
is not unitary with the piston. The larger diameter passage 94
reduces fluid friction loss through the passage 94, and
consequently across the valve assembly.
A seal ring 97, in addition, is provided around the piston 82 for
preventing the fluid in the upper chamber 83 or the lower chamber
84 from moving to the other chamber by passing through the gap
between the outer surface of the piston 82 and inner surface of the
cylinder 49 (71).
A check valve assembly 100 is principally accommodated in the
hollow 91; all of the components of the valve assembly 100 are
arranged within the hollow 91 with the valve seat 93 formed on the
upper end of the hollow 91. The check valve assembly 100 consists
of a ball 101, a retainer 102 and a spring 103. The diameter of the
ball 101 is larger than the diameter of the passage 92 so that the
ball 101 is seated at the valve seat 93. The retainer 102 retains
the ball 101. A plug 104 is provided for closing the hollow 91. The
plug 104 is a bolt-like member and is screwed into the hollow 91
which has a female threaded surface 105. The spring 103 is placed
between the retainer 102 and the plug 104 so that the ball 101 is
urged against the valve seat 93 to block fluid flow between the
upper chamber 83 and the lower chamber 84. Another passage 106 is
provided in the piston 82 for connecting the hollow 91 and the
lower chamber 84. The check valve assembly 100, the hollow 91,
passages 92, 93, 94, 95, 96 and 106 all form the shock-absorbing
mechanism (i.e., a damping mechanism). Thus arranged, fluid flow
from the upper chamber 83 is permitted to the lower chamber 84 upon
the application of a preset force tending to cause the outboard
drive 31 (61) to tilt-up about the tilt axis 41 (67). The amount of
the force required to open the valve 100 is established by the
stiffness of the spring 103, and thus such force is preset by
selecting the stiffness of the spring 103.
Like the action with the conventional arrangement, when an
underwater obstacle 106 (see FIG. 3) such as a drift wood or a rock
is struck by the outboard drive 31 (61) with sufficient force, the
piston rod 52 (73) will exert sufficient force on the piston 82 so
as to overcome the action of the check valve assembly 100. That is,
the sufficient force on the piston 82 moves the ball 101 to an open
position against the bias of the spring 103. Thus, the fluid in the
upper chamber 83 can flow into the lower chamber 84 through the
passages 94, 95 and 96 in the piston, and through the upper passage
92, the valve seat 93 the hollow 91, and the lower passage 105 in
the piston 52 (73). The flow of the fluid from the upper chamber 83
to the lower chamber 84 allows the piston 82 to move upwardly as
indicated with the arrow 107 and permits the outboard drive 31 (61)
to pop-up as indicated by the arrow 108 in FIG. 3. After striking
the underwater obstacle, the fluid in the lower chamber 84 must
return to the upper chamber 83 in order to lower the outboard drive
31 (61) down. For this purpose, a manual valve 109 (see FIG. 9) is
provided between the upper opening 89 and the lower opening 90 of
the cylinder 49 (71). Thus, when an operator opens the manual valve
109, the fluid in the lower chamber 84 immediately returns to the
upper chamber 83 and then the outboard drive 31 (61) can be
lowered.
In this first embodiment as described above, in addition to the
compact nature, the check valve assembly 100 can be easily inserted
into and removed from the hollow 91 and then closed by the plug
104. Further, since the piston rod 52 (73) is formed separately
with the piston 82, the passage 94 as well as the branch passages
95 and 96 may have a diameter larger than that of the valve seat
93. Accordingly, machining of these apertures 94, 95 and 96 with
such a relatively long and slim rod member can be easily done also.
Furthermore, the piston rod 52 (73) can be jointed with the piston
82 by screw connection. Thus, durable connection of the both
members is ensured.
Another preferred embodiment is shown in FIG. 10. The same members
or components as described in connection with the arrangement shown
in FIGS. 7 and 8 have the same reference numerals so as to avoid
repetitions and to indicate common components between the two
embodiments. Accordingly, unless indicated otherwise, the foregoing
description of such common components should be understood to apply
equally to the corresponding components of the present
embodiment.
The piston 110 is somewhat longer than the piston 82 and the
passage 111 is also longer than the upper passage 92 in the first
arrangement. The opening of the passage 111 is closed with a small
plug 112 and another passage 113 is pierced between a middle
portion of the passage 111 and the upper chamber 83 so that the
hollow 91 can be connected with the upper chamber 83. The diameter
of the branch aperture 113 is slightly larger than that of the
passage 111.
A bulge 114 is formed at the top of the piston 82 and a recess 115
is made at the bulge 114. The lower end of a piston rod 116 is
forced into the recess 115. Thus, the piston 82 and the piston rod
116 are connected by press fitting. The other structure is the same
as described with the first embodiment.
In this embodiment, when an underwater obstacle is struck, the same
action occurs in the shock absorbing arrangement and the fluid in
the upper chamber 83 may flow into the lower chamber 84 through the
passages 113 and 111, the hollow 91 and the passage 106. The flow
of the fluid from the upper chamber 83 to the lower chamber 84
allows the piston 82 to move upwardly and the drive unit to pop-up.
After the strike of the underwater obstacle, the fluid in the lower
chamber 84 will return to the upper chamber 83 from the lower
chamber 84 by opening the manual valve 109 (FIG. 9) as described
with the first embodiment. Thus, the outboard drive 31 (61) may be
lowered.
Because of the arrangement above noted, in addition to the compact
nature and the advantage of the easy assembling, no machining of
the piston rod 116 is necessary. Thus, manufacturing cost can be
saved.
It should be noted that in either of the embodiments described
above, the plug 104 might have an aperture (passage) that
penetrates its body so that the hollow 91 is connected with the
lower chamber 84 through this passage. This passage could be in
place of or in addition to the lower passage 106. It also is
understood that the piston could include a plurality of upper
passages 113 and lower passages 106.
It should be also noted that another arrangement is applicable for
returning the fluid in the lower chamber to the upper chamber after
pop-up. FIG. 11 shows this arrangement schematically. For the
purpose, a return check valve 120 is provided in the piston 121 as
well as a shock absorber valve 122 that is described above in
detail. This return check valve 120 is much smaller than the shock
absorber valve 122. Because the return valve 120 has no spring. In
addition, a diameter of its ball is smaller that the diameter of
the ball 101 of the shock absorber valve 122. In an exemplary
embodiment, the diameter of the return check valve ball is around 3
mm or 4 mm and a diameter of the ball of the shock absorber valve
122, in turn, is around 13 mm or 15 mm. A free piston 123 is
provided in the lower chamber 84 for memorizing a tilt up angle by
well known principle.
When an underwater obstacle is struck, the same action occurs in
the shock absorbing arrangement and the fluid in the upper chamber
83 may flow into the space between the piston 121 and the free
piston 128 in the lower chamber 84 through the shock absorber valve
122. The flow of the fluid from the upper chamber 83 to the lower
chamber 84 allows the piston 121 to move upwardly and the drive
unit to pop-up. After the strike of the underwater obstacle, the
fluid in the space of the lower chamber 84 will return to the upper
chamber 84 from the lower chamber 83 through the return valve 120
and then the outboard drive 31 (61) may be lowered immediately
without operating the manual valve 109.
The manual valve 109, therefore, in this arrangement is only used
for urgent release of fluid for tilt down in case of malfunction.
In addition, the return valve 120 can be provided in a tilt
cylinder 45 (70) that incorporates no free piston. However, if the
free piston 123 is applied, the return valve 120 is indispensable.
Although the return valve 120 is placed in the periphery of the
piston 121, the valve 120 is quite small as described above. Thus,
the tilt cylinder 45 (70) may still keep a slimed body.
Although this invention has been described in terms of certain
embodiments, other embodiments apparent to those of ordinary skill
in the art are also within the scope of this invention.
Accordingly, the scope of the invention is intended to be defined
only by the claims that follow.
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