Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention is particularly adapted for
use in a water jet propulsion system for seacraft, particu-
larly hydrofoil ships. In a propulsion system of this type,
water is scooped up from a body of water traversed by the
ship, energy is added to the water by means of a pumping
element driven by an engine, the water is discharged in the
form of a driving jet to propel the skip, and reverser buc-
ket means is provided to selectively and controllably move
into the path of travel of the driving jet to reverse the
lQ thrust of the ship. The jet is normally discharged above
the water line so as to reduce back pressure.
In a propulsion system of this type, it is neces-
sary to provide a throttle control which, among other things, -
has a neutral setting which positions the reverser bucket
in the jet stream to give a zero net thrust. Additionally,
an engine idle region should be provided which will allow
bucket modulation of the jet stream to give forward and re-
verse boat speed control at the engine idle setting, this
being normally for docking and the like purposes. However,
it is also desirable to provide a neutral hold feature which
will allow throttle advance without bucket deployment for
the purpose of engine testing and start-up procedures. A
control of the type described above can be implemented with
solid-state electronic systems; however these are complex
and excessively costly.
In accordance with the present invention, there i9
provided control means for the driving engine and reverser
bucket means of a water jet ship propulsion system which,
in~tead of using expensive solid-state electronic controls,
utilizes special potentiometers with shorted sections, along
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with a minimum of circuit components to achieve the
requirements set out above.
Specifically, there is provided in a ship
propulsion system of the type in which water is scooped
from a body of water traversed by the ship, energy is
added to the water by means of a pumping element driven by
an engine, the water is discharged in the form of a driving
jet to propel the ship, and reverser bucket means is
provided to selectively and controllably move into the path
of travel of the driving jet to reverse the thrust of the
ship; the improvement in control means for said driving
engine and reverser bucket means comprising: first means
including electrically-operated valve means for controlling
the speed of said engine and the amount of energy added to
the water by said pumping element; second means including
electrically-operated valve means for controlling movement
of said reverser bucket means into the path of travel of
said driving jet; a throttle having neutral, forward and
reverse positions; first potentiometer means having a
wiper element operatively connected to said throttle and
having a pair of resistive contact; sections spaced apart
by a non-resistive contact section at the neutral position
of said wiper and connected to the first means for
controlling the speed of said engine whereby the engine
will idle at the neutral position and in regions on either ` :
side of neutral~ and second potentiometer means having a
wiper element operatively connected to said throttle for `
controlling the position of said reverser bucket means and
having shorted sections on either side of a central
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resistive section whereby, as said throttle moves through
said regions on either side of neutral, the reverser
bucket means will move from a fully-retracted position for
forward thrust to a fully-extended position for reverse
thrust.
The above and other objects and features of the
invention will become apparent from the following detailed
description taken in connection with the accompanying - ~ -
drawings which form a part of this specification, and in
which:
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Figure 1 is a perspective aft view of the ctern
portion of a hydrofoil craft incorporating a water jet pro-
pulsion system and with which the control system of the
present invention may be used;
Figs. 2, 3 and 4 are side views showing the manner
in which the reverser bucket means of the propulsion system
may be moved from a fully-retracted position to a fully-
extended position wherein the entirety of a jet stream i
deflected backwardly;
Fig. 5 is a schematic circuit diagram of the con-
trol system of the invention; and
Fig. 6 schematically illustrates the operation of
the invention.
With reference now to the drawings, and particular-
ly to Fig. 1, there is shown the aft portion of a hydrofoil
10 having downwardly-depending struts 12 and 14 intercon-
nected at their lower ends by means of foils 16 and 18. The
foils have control surfaces 20 and 22, respectively, at
their trailing edges. At the bow of the craft, not shown,
is a third downwardly-depending strut which acts as a rudder
and which carries at its lower end a foil. The struts 12
and 14 and the foils carried thereby can be rotated upwardly
into a retracted position about a pivot point 24.
The present invention is concerned with the propul-
s~on means for the hydrofoil craft. Propulsion i8 obtained
by means of jet streams of water passing out of nozzles 26
and 28 on either side of the craft. Water is scooped from
the sea through an opening 30 at the forward end of a foil
section 32 and is then directed upwardly through a center
column 34 to port and starboard pumps, not shown, driven by
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port and starboard prime movers such as jet engin~. From
the pumps, the water is then discharged through tho nozzles
26 and 28 which propel the craft forwardly. In order to ob-
tain reverse motion of the craft, reverser bucket devices
36 and 38 are provided for each of the nozzles 26 and 28.
For forward motion of the craft, the bucket assembles 36
and 38 are rotated into positions where they do not inter-
sect the issuing jet stream. However, by rotating the buc-
ket assemblies 36 and 38 into the jet stream, the jet is
deflected backwardly to thereby obtain reverse thrust.
The operation of the reverser bucket assembliss is
perhaps best shown in Figs. 2, 3 and 4. The water jet, in-
dicated by the reference numeral 40, issues from a nozzle
42 and passes through a cylindrical member 44 which can be
lS tilted upwardly or downwardly to deflect the jet stream.
However, the manner in which this is accomplished will not
be described herein. The reverser bucket means itself com-
prises a dished or curved member 46 pivotally connected to
a support member, not shown, by means of side arms 48 which
are, in turn, connected through a linkage 50 to the piston
; of a pneumatic or hydraulic cylinder 52. Provided in one
side of the dished portion 46 is an opening 54, the arrange-
ment being such that as the dished portion 46 is moved down-
wardly by pressurization of cylinder 52, more and more of
the dished portion 46 will intersect the jet stream as shown
in Figs. 3 and 4. As it does intersect the jet stream, the
water is propelled to the side and backwardly out through
the opening 54, thereby creating a reverse thrust for the
craft.
The propulsion control system of the invention is
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shown in Fig. 5 wherein elements oorresponding to those of
Figs. 1-4 are identified by like reference numerals. As
was explained above, water is scooped through opening 30
(also identified in Fig. 1) and then passes upwardly through
~he center column 34 to a pump 56 driven by a prime mover
58, such as a jet engine. From the pump 56, the water is
driven through the nozzle 42, thereby creating the jet stream
40 which can be intersected by the dish-shaped reverser
member 46 to deflect the stream backwardly. Member 46, in
turn, is carried on side members 48 connected through the
linkage 50 to the piston rod of cylinder 52. It will be
understood, of course, that in an actual installation, there
are two jets and accompanying propulsion means, only one
being shown in Fig. 5.
Opposite ends of the cylinder 52, in turn, are con-
nected through valve 60 to a source 62 of fluid under pros-
sure. The valve 60 is adapted to connect the source of ~-
fluid under pressure to either end of the cvlinder 52 such
that rotation of the dished member 46 can be in either dir- ~ -
ection, depending upon the position of the valve. The valve
60, in turn, is controlled by means of an electrical actuator
64 provided with a control winding 66. The actuator 64 is
such that when the voltage at the opposite ends of the wind-
ing 66 is the same, then the actuator 64 will stop. However, ~ ;when the voltage becomes unbalanced, the actuator will turnin one direction or the other to move the valve 60 until
the voltages are again equal.
Manual control for the craft is by way of a throttle
68 which may be moved in one direction for forward movement
of the craft and in the reversç direction for astern movement
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The throttle 68 is connected through a mechanical linkage
70 to the wiper elements 72 and 74 of potentiometers 76 and
78, respectively. The potentiometer 76 is included in the
throttle circuit 80~ while the potentiometer 78 is part of
a reverser circuit 82.
Both ends of the potentiometer 76 are connected to
the positive terminal 84 of a source of direct current volt-
age, not shown; while opposi~e ends of the potentiometer 78
are connected to the opposite terminals 84 and 86 of the
same source of direct current potential. The potentiometer
76 includes a central shorted section 88 whose center point
is connected through a resister 90 and an idle trimming pot -
92 to the terminal 86. On one side of the shorted section
88 of potentiometer 76 is a reverse resistive section 94;
and on the other side of the shorted section 88 is a for- -
ward resistive section 96, this being shorted by means of
resi~tors 98 and 100 for a purpose which will be hereinafter
described. The upper end of the forward resistive section
96 is connected through a forward trim pot 102 to the termi-
nal 84; while the lower end of the reverse resistive section
94 is connected through a reverse trim pot 104 and resistor
106 to the same terminal 84. ~ -
With the wiper element 72 in the shorted sector or
ldle position shown, the resistance of the potentiometer
and resistances 90 and 92 make a voltage divider. As a
result, with the throttle 68 in its shorted sector or idle
position, current will flow from the wiper element 72 to an
electropneumatic valve 108 back to the terminal 86 to estab-
lish an idle speed for the prime mover 58 which can be set
by resistor 92. Furthermore, as the throttle is moved in
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ei~her the astern or forward direction from its dead center
or null position, its idle speed will persist for a period
by virtue of the shorted section 88. However, as the wiper
element 72 moves beyond the shorted section 88 in either
direction, the voltage across the electropneumatic valve
108 will be increased to increase the speed of the prime
mover 58 and, hence, the thrust imparted by the water jet
40.
Since the wiper element 74 on potentiometer 78 is
also connected to the mechanical linkage 70, the two wiper
elements 72 and 74 will move in unison. However, when the
wiper element 74 is at the central or idle region, it con-
tacts a resistive section 110 which is bounded on either
side by ~horted sections 112 and 114. The sections 112 and ~ .:
114 are connected through trimming pots 116, 118, respec- -
tively, to the positive and negative terminals 84 and 86 of .~ ~ :
the direct current voltage source.
In shunt with the potentiometer 78 is a second vol-
tage divider comprising equal resistors 120 and 122 in series
with a trimming pot 124. The midpoint between resistors
120 and 122 is adapted to be connected through contacts 126
of relay 128 and resistor 130 to one side of the control
~inding 66 for the servo dev~ce 64. Ordinarily, however,
the relay 128 will be deenergized such that the vable tap
74 of potentiometer 7% is connected through resistor 130 to
the winding 66. The other side of the winding 66 is con-
nected to a movable tap 132 on potentiometer 134 connected .
between the positive and negative terminals 84 and 86. It
- can be seen, therefore, that as the tap moves back and forth
30 on the resistive section 110, ~ne servo device 84 will move
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the valve 60 while the tap 132, mechanically connected to
the linkage 50, moves ;n a like amount until the bridge
circuit is again balanced and the servo device 64 stops.
The system includes a neutral hold feature compris-
ing a manually-operable switch 136 and a switch 138 con-
nected to the throttle 68 and which is closed when the throt-
tle is in its neutral position. Assuming that switches 136
and 138 are closed, relay 12~ will become energized and will
remain energized until manual switch 136 is opened by vir-
tue of holding contacts 140. At the same time, energization
of relay 128 acts to connect the midpoint of resistors 120
and 122 to the control winding 66 such that the position of
the servo 64 is maintained at the neutral setting by the
position of the tap on pot 124.
The operation of the invention can perhaps best be
understood by reference to Fig. 6 which shows the throttle
travel limits and the relation of the two throttle-coupled ~ -
potentiometers and their signal output requirements as a
function of throttle lever position. Waveform A in Fig. 6
illustrates the signal appearing on the tap 74 of the rever-
ser potentiometer 78; whereas waveform B represents the sig-
nal on the tap 72 of potentiometer 76. The taps 74 and 72
are shown in their neutral positions in Fig. 6.
As tap 72 moves to the right or let of its central
or neutral position, and assuming that it still contacts the
shorted section 88, the output signal from the tap shown by
waveform ~ remains constant with the prime mover rotating
the pump 56 at a speed of 6000 revolutions per minute. How-
ever, as the tap 72 moves beyond the shorted section 88 in
either the reverse or forward direction, the resistive
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section 96 or 94 is contacted whereby the output signal
(waveform B) increases. In the case of reverse thrust, the
output signal increases to the point where the engine or
prime mover 58 rotates at a speed of 7600 revolutions per
minute; whereas in the forward direction, it advances until
the prime mover rotates at a speed of 13,250 revolutions per
minute. The shunts 98 and 100 are utilized to linearize the ~ - -
throttle relationship as the tap 72 moves along the resis~
tive section 96. ~ -
At the same time that tap 72 is moving back and
forth, the tap 74 is also moving as explained above. However,
in contrast to the throttle signal, the reverser signal in-
creases from a negative value on the forward side of neutral
to a positive value. In this process, the reverser bucket
means is moved from a fully-retracted position such as that
shown in Fig. 2 to a fully-extended position such as that
shown in Fig. 4 wherein the ~et stream is fully deflected
for reverse thrust. In-between the fully-retracted and
fully-extended positions, the engine is idling at a speed
of 6000 revolutions per minute; while the position of the
bucket can be adjusted to give forward and reverse boat
speed control. When switch 136 is closed and the throttle
68 is at its neutral position, relay 128 will be energized
whereby the position of the reverser bucket will be fixed
as determined by the pot 124. Under these circumstances,
the throttle can be advanced in either the forward or re-
; verse direction without altering the position of the rever-
ser bucket which allows for engine testing and start-up.
Although the invention has been shown in connec-
tion with a certain specific embodiment, it will be readily
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apparent to those skilled in the art that various changes
in form and arrangement of parts may be made to suit re-
quirements without departing from the scope of the appended
claims.
