U.S. patent number 3,842,789 [Application Number 05/317,062] was granted by the patent office on 1974-10-22 for hydraulic trim/tilt system for outboard propulsion units.
This patent grant is currently assigned to AB Volvo Penta. Invention is credited to Karl Abdon Bergstedt.
United States Patent |
3,842,789 |
Bergstedt |
October 22, 1974 |
HYDRAULIC TRIM/TILT SYSTEM FOR OUTBOARD PROPULSION UNITS
Abstract
A hydraulic system for trimming and tilting outboard drives for
boats. The system comprises a pump adapted to deliver fluid
pressure to a double acting cylinder-piston assembly, which is
connected to the tiltable outboard drive unit and to a stationary
part of the boat. A valve selects between two modes of operation of
the cylinder. In one mode the chambers of the cylinder are
interconnected to provide rapid tilt operation. In the other mode,
one chamber is connected to the pump and the other is connected to
the fluid sump to provide relatively less rapid trimming with
greater force.
Inventors: |
Bergstedt; Karl Abdon
(Goteborg, SW) |
Assignee: |
AB Volvo Penta (Goteborg,
SW)
|
Family
ID: |
20302197 |
Appl.
No.: |
05/317,062 |
Filed: |
December 20, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Dec 21, 1971 [SW] |
|
|
16407/71 |
|
Current U.S.
Class: |
440/61R;
440/61D |
Current CPC
Class: |
F15B
11/024 (20130101); B63H 20/10 (20130101); F15B
2211/40515 (20130101); F15B 2211/50518 (20130101); F15B
2211/20561 (20130101); F15B 2211/46 (20130101); F15B
2211/41527 (20130101); F15B 2211/613 (20130101); F15B
2211/27 (20130101); F15B 2211/5157 (20130101); F15B
2211/3058 (20130101); F15B 2211/50545 (20130101); F15B
2211/329 (20130101); F15B 2211/30505 (20130101); F15B
2211/775 (20130101) |
Current International
Class: |
B63H
20/00 (20060101); B63H 20/10 (20060101); F15B
11/00 (20060101); F15B 11/024 (20060101); B63h
005/12 () |
Field of
Search: |
;115/41R,41HT,34R,34A
;91/436,437 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Blix; Trygve M.
Assistant Examiner: Frankfort; Charles E.
Attorney, Agent or Firm: Baldwin; George H. Yeager; Arthur
G.
Claims
What is claimed as new and what it is desired to secure by Letters
Patent of the United States is:
1. A hydraulic system for trimming and tilting of outboard drive
units for boats, comprising pump means adapted to deliver hydraulic
liquid from a liquid sump to a double acting cylinder-piston
assembly, said cylinder-piston assembly being arranged between said
tiltable drive unit and the boat or a stationary part of the drive,
characterized by a valve unit, said valve unit being adjustable
between a first position and a second position and comprising means
for connecting said pump means to the chamber at the piston rod end
of the cylinder and to the chamber at the piston end of the
cylinder when said valve unit is in said first position to tilt
said drive unit and for disconnecting said chamber at said piston
rod end of said cylinder from said chamber at the piston end of
said cylinder and for connecting said chamber at said piston rod
end of said cylinder with said sump when said valve unit is in said
second position to trim said drive unit, and manual control means
for adjusting said valve unit between its said positions.
2. In a hydraulic system for trimming and tilting an outboard drive
leg for boats about a horizontal tilt axis comprising a hydraulic
liquid sump, a double acting hydraulic cylinder-piston assembly
including a piston rod and having a cylinder with a piston therein
dividing the space in the cylinder into a first chamber at the
piston end and a second chamber at the piston rod end of said
cylinder, means connecting said cylinder and rod between said leg
and said boat and spanning said axis, and a reversible pressure
liquid pump connected to said first chamber, valve means connected
to said sump and to each of said chambers adjustable between a
first and a second position and comprising means for connecting
said second chamber to said first chamber when in said first
position to tilt said drive leg and for connecting said second
chamber to said sump when in said second position to trim said
drive leg, and manual control means for adjusting said valve means
between its said two positions.
3. In a drive unit for a boat including a hydraulic system for
trimming and tilting an outboard drive leg about a horizontal tilt
axis, said system comprising a hydraulic liquid sump, a double
acting hydraulic cylinder-piston assembly including a piston rod
and having a cylinder with a piston therein dividing the space in
the cylinder into a first chamber at the piston end and a second
chamber at the piston rod end of said cylinder, means connecting
said cylinder and rod between said leg and said boat and spanning
said axis, and a source of pressure liquid connected to said first
chamber, said unit comprising a forward, neutral and reverse gear
transmission and manually movable means for shifting said gears,
said system being characterized by including valve means connected
to said sump and to each of said chambers adjustable between a
first and a second position and comprising means for connecting
said second chamber to said first chamber when in said first
position to tilt said drive leg and for connecting said second
chamber to said sump when in said second position to trim said
drive leg, and means coupling said valve means to said manually
movable means for coordinate adjustment thereof between said
positions in response to gear shifting movement of said manual
means.
4. The combination according to claim 3, characterized in that said
valve means is further adjustable into a third position into which
it is adjusted in response to movement of said manually movable
means into the position to shift said gear transmission into
reverse, and said valve means further comprises means for closing
off said second chamber when in said third position.
5. The combination according to claim 3 wherein said means coupling
said valve means to said manually movable means includes a lost
motion connection.
6. The combination according to claim 3 wherein said means
connecting said valve means to said manually movable means includes
a lost motion connection, and wherein, upon movement of said
manually movable means to shift said transmission gears from
reverse into neutral, said valve means is thereby adjusted into its
said first position, and, upon further movement of said manually
movable means to shift said transmission gears from neutral into
forward gear, said valve means is adjusted thereby into its said
second position, said lost motion connection being operative, upon
return movement of said manually movable means from its forward
gear position to shift said transmission gears into neutral, to
render said connecting means inoperative to return said valve means
into its said first position.
7. The combination according to claim 6, characterized in that said
valve means is further adjustable into a third position into which
it is adjusted in response to movement of said manually movable
means into the position to shift said gear transmission into
reverse, and said valve means further comprises means for closing
off said second chamber when in said third position.
8. In a drive unit for a boat including a hydraulic system for
trimming and tilting an outboard drive leg about a horizontal tilt
axis, said system comprising a hydraulic fluid sump, a double
acting hydraulic cylinder-piston assembly including a piston rod
and having a cylinder with a piston therein dividing the space in
the cylinder into a first chamber at the piston end and a second
chamber at the piston rod end of said cylinder, means connecting
said cylinder and rod between said leg and said boat and spanning
said axis, and a selectively operable pressure fluid pump means
connected to said first chamber, said unit comprising a forward,
neutral and reverse gear transmission and manually movable gear
shift means for shifting said gears between forward, neutral and
reverse, said system being characterized by including valve means
connected to said sump and to each of said chambers adjustable
between first, second, third and fourth positions, said valve means
comprising means to open hydraulic connection between said second
chamber and said first chamber when in said first position, to open
hydraulic connection between said second chamber and said sump in
said second and third positions, and closing off hydraulic
connection to said second chamber in said fourth position, means
coupling said valve means to said manually movable means for
adjustment thereof coordinate with movement of said manually
movable means and operable to adjust said valve means into said
first position in response to movement of said manually movable
means to shift gears from reverse to neutral, to adjust said valve
means into said second position in response to movement of said
manually movable means to shift gears from neutral into forward, to
adjust said valve means into said third position in response to
movement of said manually movable means to shift gears from forward
to neutral, and to adjust said valve means into said fourth
position in response to movement of said manually movable means to
shift gears from neutral into reverse, said lost motion means being
effective, upon said movement of said manually movable means to
shift gears from forward into neutral, to not adjust said valve
means from said third to said first position and, upon said
movement to shift gears from reverse into neutral, to not adjust
said valve means from said first to said third position.
Description
Applicant claims priority based on Swedish application No.
16407/1971 filed Dec. 20, 1971.
BACKGROUND OF THE INVENTION
In tilting and trimming outboard drives, two main requirements are
to be met. In one case, the tilt movement, when the boat lies still
and when no propeller thrust acts on the drive, a wide range of
tilting is to be performed in a short time. Under this condition,
only a relatively small force is needed. In the second case, the
trimming movement, when the boat is driven and the drive is
subjected to the propeller thrust, a relatively greater force is
needed to achieve the trimming movement. On the other hand the trim
angle is small and a low speed of the trimming movement is
desirable to permit accurate setting of the trim angle.
It is known, for example from U.S. Pat. No. 3,548,777 - Bergstedt,
to fulfill the above named requirements by utilizing one hydraulic
cylinder with a relatively small piston area for tilting and a
second cylinder with a relatively large piston area for trimming.
By this arrangement it is possible to achieve both the quick
tilting movement and the slow trimming movement with one pump with
constant capacity.
It is, of course, preferred for economy, simplicity and space
considerations to use one, rather than two cylinders for trimming
and tilting.
It is an object of the present invention to provide a hydraulic
system with which it is possible to achieve the above named
trimming and tilting functions by using only one cylinder. This is
accomplished by a valve unit in the hydraulic system which is
adjustable between a first position, in which the chamber at the
piston rod end of the cylinder is connected to the chamber at the
piston end of the cylinder, and a second position, in which the
chamber at the piston rod end of the cylinder is connected to the
sump tank.
In the first position of the valve unit, in which it provides a
short circuit between the two chambers of the cylinder, the fluid
pressure delivered by the pump to the cylinder will act on the
difference between the piston areas of the two chambers of the
cylinder, i.e., on the cross-sectional area of the piston rod.
Since this area is much smaller than the total piston area exposed
to the chamber at the piston end of the cylinder, the fluid will
cause a fast movement of the piston and little force, which is
desired during tilting.
It is preferred that the cylinder-piston assembly is arranged, as
in said U.S. Pat. No. 3,548,777, so that an outward movement of the
piston rod causes an upward tilting of the drive unit.
In the second position of the valve unit the chamber at the piston
rod end of the cylinder is drained by a connection to a sump tank.
When fluid pressure is then delivered to the piston area, it causes
a slow motion of the piston rod with great force which results in a
slow upward swinging of the drive with a force which is able to
overcome the propeller thrust when trimming during forward driving
of the boat.
As the propeller thrust must be overcome when trimming underway,
the pressure delivered by the pump must be much higher than during
tilting.
According to this invention, the valve unit comprises a valve
member which is manually adjustable between the first and the
second position. In this embodiment, the manually adjustable valve
member is preferably co-ordinated to a known locking valve, which
is connected to the reverse gear of the drive and adapted to lock
the connection between the piston rod side of the cylinder and the
tank when shifting from forward to reverse drive.
Such shifting between trim and tilt is achieved, as hereinafter
seen, without using any additional control units which should
complicate the maneuvring of the boat.
The hydraulic system according to the invention will be fully
understood from the following description which refers to the
accompanying drawings.
FIG. 1 is a side view of an inboard-outboard drive unit for a boat
embodying the invention;
FIG. 2 is a schematic view of a previous known hydraulic trim/tilt
system with two cylinders;
FIG. 3 is a schematic view of a second embodiment of the invention
with a manually adjustable valve unit;
FIGS. 4a, 4b, 4c and 4d are schematic views of the different
positions of the manually adjustable valve unit; and
FIG. 5 is a schematic side view of the adjusting mechanism for the
valve unit in FIGS. 4 a-d.
This invention contemplates an outboard drive unit for a boat, such
as the inboard-outboard unit shown in FIG. 1 as comprising an
outboard leg 60 mounted for tilting on a pivot 61 to the boat
transom 62. The leg is arranged for steering, for example, as shown
in U.S. Pat. No. 3,605,677 - Bergstedt, and is provided with a
cylinder 63 rockably connected to a fixed portion 64 of the boat or
drive unit and with an extensible piston rod 36 pivotally connected
to the leg, whereby extension of the rod causes rearward trimming
or tilting movement of the leg about pivot 61. A control cable or
rod linkage 56, 58 leads from a housing 65 which may form an
integral part of the cylinder and in which control valves of the
system are contained. A pump and fluid pump schematically shown at
P is connected by means of fluid conduits schematically represented
at 66 to supply pressure fluid to and receive return fluid from the
control system. A forward, neutral and reverse gear transmission of
the unit is controlled by lever 67 linked to lever 56.
The known hydraulic system showed in FIG. 2 comprises a reversible
pump 1 which can deliver fluid in both directions, and it is
therefore connected to the sump tank 6 over two lines 2 and 3 with
back pressure valves 4 and 5. The pump is also connected to the
sump tank via lines 7 and 8 comprising safety relief valves 9 and
10. The lines 2 and 3, of which one acts as a suction line and the
other as a pressure line depending on the pump direction of the
pump 1, connect the pump to two regulating valve units 11 and 12,
of which the first one 11 communicates, via the lines 13 and 14,
with the chamber 16 at the piston end of a double acting tilt
cylinder 17 and also with a single acting trim cylinder 19 in order
to regulate the fluid flow to and from these cylinders. The other
regulating valve unit 12 communicates, via the line 15, with the
chamber 20 at the piston rod end of the double acting cylinder 17.
Both valve units 11 and 12 also communicate with the sump tank via
respective return lines 21 and 22. Units 11 and 12 comprise
respective piston means 25 and 26, which are influenced by the
pressure in lines 3 and 2 and which are spring biased by respective
compression springs 23 and 24 against the pressure in the
respective lines. The piston means 25 controls the communication
between sump return line 21 and lines 13 and 14 depending on the
pressure in line 3, while piston means 26 controls the
communication between sump return line 22 and line 15 depending on
the pressure in line 2.
The hydraulic system further comprises a lock valve 27, which is
manually adjustable and is interposed in the line 15 which
communicates with the chamber 20 in cylinder 17. The system also
comprises a safety relief valve 29 in a short circuit line 28
connecting between lines 12 and 15.
Another safety relief valve is disposed in a channel in the piston
32, said channel connecting chambers 16 and 20 of the double acting
cylinder to each other.
Finally, the system also comprises a line 33, which via a relief
valve 48 connects line 13 to the sump tank.
The described system suffers of very little, actually neglectable,
leakage and keeps the pistons 32 and 34 of the cylinders 17 and 19
in their adjusted positions. The hydraulic cylinders are adapted to
act between a stationary part of the boat and the tiltable part of
the drive unit in such a way that an outward movement of the
respective piston rods 35 and 36 causes an upward swinging movement
of the drive. This arrangement, being well known in the art, is
therefore not further shown in the drawings.
When the angular position of the drive unit is to be adjusted, for
upward or downward tilting or trimming, the pump is actuated and
connected in the desired direction until the desired position of
the drive unit is achieved.
When the drive unit is to be tilted from drive position when the
boat is lying still or is not being driven forward, the function of
the system is as follows:
The pump is actuated and connected in a direction which makes the
line 3 constitute a suction line and the line 2 a pressure line.
The pressure in line 2 opens a spring biased back pressure ball
valve 37 in the regulating valve unit 11, whereupon the fluid under
pressure is delivered to chambers 16 and 18 in the cylinders 17 and
19 via lines 13 and 14.
Simultaneously, the pressure in line 2 causes the piston 26 in the
regulating valve unit 12 to move to the right as seen in FIG. 2 and
thus to force open a back pressure valve 38 in the valve unit 12,
whereupon chamber 20 in the cylinder 17 communicates with the sump
tank 6 via the line 15 and the return line 22. The trimming
cylinder has a relatively short stroke. As the piston 32 of the
cylinder 17 has a smaller area than the piston 34 of cylinder 19
and as the same pressure prevails in the cylinder chambers 16 and
18, a fast outward movement of the piston rod 35, and thus a fast
tilting of the drive, is achieved after the piston 34 has reached
its limit. As seen in U.S. Pat. No. 3,548,777, the rod 36 is so
arranged that the outboard leg swings away therefrom beyond the
trim range.
For downward tilting of the drive the pump is actuated in the
opposite direction, so that line 3 constitutes a pressure line and
line 2 a suction line. It will be apparent that the direction of
rotation of the pump may be reversed to provide pressure to line 3
and to draw fluid from line 2 or that merely the input and output
connections to the pump may be reversed to provide this result
without reversing the actual direction of rotation of the pump
itself. Via a spring biased back pressure valve 39 in the
regulating valve unit 12 fluid is delivered to chamber 20 in the
cylinder 17. Simultaneously, the pressure in line 3 causes piston
25 in the valve unit 11 to open a spring biased back pressure valve
in the valve unit 11, whereupon the cylinder chambers 16 and 18
communicate with the tank 6 via the line 13, the back pressure
valve 40 and the return line 21. In this case an inward movement of
the piston 32 and finally of both pistons 32 and 34 and a downward
movement of the drive are achieved.
When the boat is propelled, whereby the piston rods 35 and 36 are
exposed to the force caused by the propeller thrust which tends to
press the pistons inwardly, the cylinder 17, due to its small
piston area, is not able to produce an outwardly directed force
which is enough to overcome the propeller force and accomplish a
short movement of the drive for trimming. At trimming, whereby the
fluid flow corresponds to the above described one for tilting, the
short movement of the drive is instead accomplished primarily by
the cylinder 19 with the piston 34 which has a larger piston area,
assisted to some extent by the lesser force of piston 32.
It shall be mentioned in this connection that the cylinder 19 is
preferable positioned so that a relatively long moment arm is
obtained, which is made possible by the fact that only a relatively
short swinging motion is needed for trimming compared with tilting.
The cylinder 17, however, is positioned so that a relatively short
moment arm is obtained, in order to get a fast and wide swinging
movement.
Of the other valves 27, 29 and 30 which are comprised in the
hydraulic system, the valve 27 works as a lock valve which is
manually adjustable together with the gear mechanism of the drive
in order to block the drainage from the cylinder chamber 20. In
this way it is ensured that the drive will not be tilted by the
rearwardly directed propeller force during reverse drive. The valve
29 is a safety release valve which permits drainage of the chamber
20 if the drive is exposed to an extreme rearwardly directed force,
for example upon impact with a submerged or floating object. Valve
30 has the same function when the lock valve 27 is in its locking
position.
The hydraulic system according to the invention will hereafter be
described with reference to FIGS. 3, 4a, 4b, 4c, 4d, and 5 in which
the components corresponding to those in FIG. 2 have been given the
same numbers as in FIG. 2. The system showed in FIG. 3 connects at
fluid lines 13, 15 and 33 to the system as shown in FIG. 2. The
difference between the system according to this invention as shown
in FIG. 3 and the prior art system of FIG. 2 lies, as will be seen,
in the omission of cylinder 19, in the substitution of valve 50 for
valve 27, and in the provision of short circuit line 52.
Furthermore, since in the FIG. 2 system, the cylinder 17 performs
the tilting function and the function of preventing tilting
movement of the outboard leg during operation in reverse gear,
whereas cylinder 63 according to the invention performs these
functions as well as the function of trimming the leg during
forward driving of the boat, the cylinder 63 should be of larger
dimensions, for a drive unit of the same power, than are required
for the cylinder 17. In other respects, cylinder 63 may be
identical to cylinder 17 as above described, being provided with a
throughpiston safety valve 30 for the purposes hereinabove
explained.
In accord with the system of FIG. 2, line 13 is pressurized when
the pump is actuated to trim or tilt the outboard leg, while a sump
return connection is opened to line 15. When the pump is actuated
in the reverse direction (or with reversed connections), line 15 is
pressurized and line 13 is opened to a sump return line. When the
pump is not actuated, lines 13 and 15 are blocked off although, as
described, the safety valves 48, 29 and 30 are provided to prevent
excessive build-up of destructive pressures therein.
According to the invention, the manually actuated valve 50 controls
or provides not only the reverse lock function (ascribed to valve
27 of the system of FIG. 2) but also control and selection of the
trimming and tilting operations.
The valve 50 comprises a rotatably movable valve member 51, which
is connected or coupled to the reverse gear control mechanism of
the drive over a "lost motion" mechanism (FIG. 5) so that shifting
of the gears of the drive unit between forward, reverse and neutral
also causes an adjustment of the valve member 51. The "lost motion"
mechanism is in the shown embodiment constituted by a control lever
56 with slots 55 in which pins 57 on the valve member 51 mesh. The
slots are dimensioned so that a 30.degree. lost motion of the
control lever is provided before the member 51 is engaged. The
control lever is connected to the reverse gear control mechanism
via a push-pull rod 58 or the like.
By using a "lost motion" mechanism two positions of the valve
member 51 are achieved in the neutral position of the drive gear
and the control lever 56, namely: a first neutral position is
achieved by shifting gears from forward drive to neutral, and a
second neutral position is achieved by shifting gears from reverse
drive to neutral. The different positions of the valve member 51
are shown in FIGS. 4a - 4d. In the position shown in FIG. 4a the
chamber 20 of cylinder 63 communicates with the sump tank 6 via a
channel 53 in the valve member 51 and via line 15. The drive gear
control is in position for forward drive. The system is now
adjusted for trimming. Upon actuation of pump 1 in one direction,
the outboard leg is slowly and forceably trimmed aft, or upon such
actuation in the opposite direction, it is slowly trimmed
forwardly. In FIG. 4b there is shown said first neutral position
which is obtained by a 60.degree. clockwise adjustment of the
control lever 56 from the position in which the drive gears are
engaged for forward drive into the position in which the gears are
in neutral. This position of lever 56 is that shown in solid lines
in FIG. 5. The lost motion between the lever and the valve member
51 is 30.degree.. The valve member is thus adjusted 30.degree. but
is still maintaining communciation between the chamber 20 and the
sump tank and the system, consequently, is still in position for
trimming as shown in FIG. 4b. Upon a further 60.degree. clockwise
adjustment of said lever to position the gears for reverse drive,
the valve member 51 is adjusted 60.degree. and blocks the drainage
from chamber 20 as FIG. 4c shows. This corresponds to the earlier
described locking position in which the drive is held down without
being influenced by the backwardly directed propeller force. Upon a
60.degree. readjustment in a counterclockwise direction of the
control lever from reverse gear position to the position in which
the gears are placed in neutral, a 30.degree. adjustment of the
valve member 51 is obtained to said second neutral position. In
this position, as is shown in FIGS. 3, 4d and 5, the valve
establishes communication between chambers 16 and 20 of the
cylinder 63 via a channel 54, the channel 53 and the short circuit
line 52. This constitutes a tilting connection for the cylinder,
and if, now, the pump is actuated in the tilting direction, the
effective piston area is the cross sectional area of the rod 35.
Finally, a further adjustment of the gear control linkage into the
forward drive gear position, with the accompanying 60.degree.
movement of the lever 56, returns the valve element 51 into the
position shown in FIG. 4a.
In operation, boats are more frequently operated in forward gear,
and only occasionally in reverse gear. So long as the gear shift
linkage is shifted between forward drive and neutral, the trimming
and tilting system remains in condition for trimming, with the
valve element moving between its positions of FIGS. 4a and 4b. If
the gears are thrown into reverse, the valve member moves into
reverse lock position, FIG. 4c, to prevent kicking up of the
outboard leg 60. In order to tilt the leg rapidly, the linkage is
shifted into reverse gear position and then returned to neutral,
valve member 51 then being in its FIGS. 3, 4d and 5 position and
lever 56 in the solid line position of FIG. 5. If the lever 56 is
not first moved into the reverse gear position and then into
neutral, tilting can be accomplished with the valve member in
either of its trimming positions of FIG. 4a or FIG. 4b, though at a
much slower rate than with the valve member in its FIG. 4d
position.
U.S. Patents having some pertinence in connection with the present
invention include No. 3,003,724 -- Kiekhaefer; No. 3,434,448 --
Woodfill; No. 3,653,270 -- Bergstedt; and No. 3,581,702 - Moberg,
in addition to No. 3,548,777 identified above.
While the invention has been described with respect to certain
specific embodiments, it will be appreciated that many
modifications and changes may be made by those skilled in the art
without departing from the spirit of the invention. It is intended,
therefore, by the appended claims to cover all such modifications
and changes as fall within the true spirit and scope of the
invention.
* * * * *