US3392696A

US3392696A - Ship

Info

Publication number: US3392696A
Application number: US493517A
Authority: US
Inventors: Jr Leo P Buckley; Randolph L Houlton
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-10-06
Filing date: 1965-10-06
Publication date: 1968-07-16
Anticipated expiration: 1985-07-16
Also published as: GB1137691A

Description

July 16, 1968 p, BUCKLE-Y, JR ET AL 3,392,696

SHIP

Filed Oct. 6, 1965 12 Sheets-Sheet 1 FIG.

INVENTORS LEO P. BUCKLEY, JR.

RANDOLPH L. HOULTON July 16, 1968 E JR ET AL 3,392,696

SHIP

12 Sheets-Sheet 2 Filed Oct. 6, 1965 y 1 1968 L. P. BUCKLEY, JR.. ET AL 3,392,696

SHIP

l2 Sheets-Sheet 5 Filed Oct. 6, 1965 SHIP l2 Sheets-Sheet 4 Filed Oct.

FUNCT'ON AHEAD SUMMING AMPLIFIER GENERATOR CONTROL LOCATION RELAY R E W I L w 3 A 4 1 1 G a m M M M w E R MR E N TU F R T G S ORI A LPSA S L B V l D llll'llll'lllll'll \r H A t K M c A 9 B m D E E F D E E P S BRIDGE THROTTLE SPEED FEEDBACK AST.

F l G. 3

July 16, 1968 Filed Oct. 6,

DIRECT CONTROL L. P. BUCKLEY, JR., ET AL SHIP 12 Sheets-Sheet 5 POSITION SENSOR VALVE TRAVEL um'r SWITCHES TURBINE GEARS ACTUATOR & VALVE LIN KAGES VALVE POSITION AHD STEAM VALVE PROPELLER LOW STEAM A 131 PRESSURE SIGNAL I STEAM (L I VALVE TACHOMETER T SPEED f DIRECT 1279 FEEDBACK CONTROL GEARS ACTUATOR (i-VALVE LINKAGES 109 RATE ASTERN ADJ.

"3 SCR CONTROL VALVE 105 VALVE POSITION VALVE TRAVEL LIMIT SWITCHES FIG. 3A

July 16, 1968 p, Uc JR" ET AL 3,392,696

SHIP

12 SheetsSheet 11 Filed Oct.

.PDnTFDO ZMEO OI o HTSQWBJJBQ WWW.

July 16, 1968 L. P. BUCKLEY, JR. ET AL 'SHIP Filed Oct. 6, 1965 12 Sheets-Sheet 12 VOLT INPUT 703 702 O ASTERN INPUT 701 AHEAD -VOLT FIG.9

United States Patent 3,392,696 SHIP Leo P. Buckley, Jr., and Randolph L. Houlton, Roanoke,

Va., assignors to General Electric Company, a corporation of New York Filed Oct. 6, 1965, Ser. No. 493,517 2 Claims. (Cl. 115-34) ABSTRACT OF THE DISCLOSURE A ship is shown with a propulsion unit. The power response reference for the propulsion unit of the ship is set at predetermined level. The power response of the propulsion unit is measured, and then the measured power response is compared with the power response reference. The difference between the measured power response and the reference power response controls the propulsion unit to bring the power response of the propulsion unit towards the reference power response.

This invention is directed to a ship, and more particularly to a ship wherein the power response from the propulsion unit is controlled automatically.

Since the age of sail, ships have been powered by several types of propulsion units. In recent years steam turbines and diesel engines have been the two principal types of conventional propulsion units. These propulsion units transform the power delivered by the propulsion units to thrust by means of one or more screw propellers at the stern of the ship. The propellers may be connected with the propulsion unit by direct lines of shafting, by mechanical gearing, or by electrical transformation. The power from the propulsion unit determines the speed at which the ship travels through the water.

The desired speed of the ship is normally determined by the officer in command on the bridge of the ship. Most merchant ships normally operate at or near full power, while naval ships normally cruise at only a fraction of full power. The instructions of the ofiicer on the bridge are normally telegraphed from the bridge to the engineering officer in the engine room, and the engineering ofiicer in the engine room acknowledges the instructions. The engine room crew then proceeds to execute the instructions.

The manner in which the engine room crew executes the bridge instructions may vary according to the propulsion unit powering the ship. The instructions may call for an increase or decrease in power response or a change in direction of the output of the propulsion unit to change the direction of travel of the ship in the water. In steam turbines steam valves must be opened and closed to increaseor decrease the amount of steam applied to the turbine. Steam may have to be removed from the ahead turbine and applied to the astern turbine to reverse the ship or to bring the ship to a stop. In diesel engines, the engine room crew takes other steps to increase or decrease the speed or reverse the direction of the ship in the water. The power response time of the propulsion unit is necessarily slow due to the communication between the commanding officer on the bridge and the engine room officer, then the subsequent communication to the engine room crew, and the time required for the engine room crew to change the valves and other controls to execute the original instructions of the commanding oflicer on the bridge. The engine room crew must then closely monitor the propulsion unit output to maintain the propulsion unit output called for by the commanding ofiicer on the bridge. The commanding oflicer on the 3,392,696 Patented July 16, 1968 bridge has no direct control over the propulsion unit output and must rely on the cooperation of the engine room officer and the engine room crew.

It is accordingly diflicult to obtain close regulation of the power response from the propulsion unit. During maneuvering with frequent speed changes required, it is especially difiicult to obtain close regulation of the power response from the propulsion unit.

It is therefore an object of this invention to provide a new and improved ship with a propulsion unit controlled automatically.

It is another object of this invention to provide a new and improved ship wherein the power response from the propulsion unit may be directly controlled from the bridge.

It is another object of this invention to provide a new and improved ship having a close regulation of the power response of the propulsion unit.

Another object of this invention is to provide a new and improved ship with a steam turbine propulsion unit wherein boiler transients are minimized in slowing down the ship.

It is an object of this invention to provide a new and improved ship with a steam turbine propulsion unit which may be easily slowed down.

Still another object of this invention is to provide a new and improved ship with a steam turbine propulsion unit where the power response of the propulsion unit is limited when the pressure to the propulsion unit falls below a safe level.

Another object of this invention is to provide a new and improved ship wherein the power response of the propulsion unit is dependent on a plurality of predetermined conditions.

According to this invention, therefore, the power response of the propulsion unit of a ship is closely controlled. A predetermined power response reference for the propulsion unit is preset. The power response of the propulsion unit is measured, and then the measured power response is compared with the power response reference. The difference between measured power response and the reference power response controls the propulsion unit to bring the power response of the propulsion unit towards the reference power response.

When a steam turbine is used as the propulsion plant, the turbine has ahead and astern sections, each turning the propeller in opposite directions. When the steam turbine is driving the ship in one direction and the decision is made to stop the ship, the predetermined power response reference is reduced to a stop power response reference. The power response is measured and compared with the stop power response reference. The difference between the measured power response and the stop power response reference is applied to the steam turbine for a predetermined period of time to turn the propeller in the opposite direction from which it has been turning to bring the ship to a faster controlled stop.

The invention is set forth with particularity in the appended claims. The principles and characteristics of the invention, as well as other objects and advantages are revealed and discussed through the medium of the illustrative embodiments appearing in the specification and drawings which follow.

In the drawings:

FIGURES 1 and 1a comprise a diagrammatic view of a ship with the propulsion unit controlled automatically according to this invention.

FIGURE 2 is a view of the bridge showing the throttle control on the bridge.

FIGURES 3 and 3a comprise a block diagram of the control for the propulsion unit.

FIGURES 4, 4a and 5 are schematics of the throttle control. v

FIGURE 6 is a schematic of the Zero shaft speed detector.

FIGURE 7 is a schematic of the speed feedback control.

FIGURE 8 is a schematic of the function generator.

FIGURE 9 is a representation of the output of the function generator.

Referring now to FIGURE 1, a ship 13 is provided with a steam turbine 14 as a propulsion plant connected through a reduction gear 15 to a propeller 16. The opening and closing of the steam valves for the steam turbine 14 are controlled at the engine room console 17. The engine room console 17 is electrically connected to the bridge console 18 on the bridge 19 of the ship. The bridge console 18 shown in the environment bridge 19 is shown in more detail in FIGURE 2. The bridge 19 is shown with a watchstander 20 at the wheel 21 controlling the direction of the ship through the water. A gyro 22 is available for reference by the watchstander 20. The bridge console 18 has a throttle lever 23 for controlling the propeller speed and the propeller direction. An engine order telegraph 24 and sound powered

phones

25 and 26 are available for communication with the engine room.

Gages

27 and 28 indicate propeller revolutions per minute and turbine throttle power response for the benefit of the crew member operating the bridge console.

The watchstander 20 on the bridge 19 positions the throttle lever 23 to call for a desired propeller and ship speed. The reference speed signal from the throttle lever 23 is applied to the valves controlling the steam flow to the turbine 14 to position the steam valves establishing a new steam flow rate. The steam flow rate in the turbine 14 produces a power response from the steam turbine 14. The power response from the steam turbine 14 is measured and compared with the reference speed signal from the throttle lever 23. If the power response from the steam turbine 14 is different from the established reference, the difference acts to open or close the proper steam valves to reduce the error and bring the power response towards the established reference.

In this particular embodiment the power response from the steam turbine 14 is measured in two different ways. The first way is to measure the actual position of the steam valve establishing the steam flow rate. This actual position of the steam valve is compared with the reference power response signal from the throttle lever 13 and the difference is applied to a valve pilot motor to move the steam valve in the proper direction to establish the proper steam flow rate. The actual speed of rotation of the propeller 16 is also measured by a tachometer to provide another measurement of the power response of the steam turbine 14. The speed of rotation of the propeller 16 is compared with the reference from the throttle lever 23 and the difference is applied to the proper steam valve to change the steam flow rate to bring the speed of rotation of the propeller 16 towards the reference.

The throttle lever 23 may be moved rapidly from the full ahead to the stop position so that the reference signal from the throttle lever becomes zero, but the propeller rotation continues so that the tachometer indicates a propeller rotation. This difference between the zero throttle reference and the forward propeller rotation activates circuits to open the astern steam valve for a short period of time to provide steam to the astern section of the turbine 14. This application of steam in the astern section may be termed bursting. The turbine 14 then actually turns the propeller in the astern direction to bring the ship to a stop position. If momentum carries the ship forward, the propeller is rotated by the water pressure in a forward direction so that there is a signal from the 4 tachometer causing another short period of steam application to the astern section of the turbine 14.

The control operates in a similar manner to bring the ship to a stop when the ship is traveling in the astern direction by applying bursts of steam to the forward section of the turbine.

In other types of propulsion units the power response may be taken at other points from the propulsion unit. For instance, in a diesel engine the fuel rack position may be used. The torque may be used also. The first stage turbine pressure may be used in a steam turbine. The power response might also be measured from thrust meter, from electrical energy on an electrical drive, or from a log (ships speed through the water) measurement.

Refer now to FIGURE 3 for a description of the block diagram of a steam turbine and its control as a propulsion unit for a ship. The throttle lever 23 shown in FIGURE 2 is connected to a potentiometer 73 in FIGURE 3 so that the potentiometer 73 produces a linear signal indicating the desired power response of the steam turbine 93. The linear signal from potentiometer 73 is applied to function generator 79 which turns the linear signal into a signal which is approximately a cubic function of the reference signal from the throttle potentiometer 73. The cubic function characteristic is required in the specific valve because the turbine power, which is linearly proportional to the steam valve position, is approximately proportional to the cubic function of the speed of the ship. It is therefore necessary that the valve position in the specific valve used be approximately the cubic function of the selected speed in terms of throttle lever position.

The reference power response signal from the function generator 79 is amplified by the ahead summing amplifier 81 and applied to the ahead SCR motor control 83 to cause the pilot motor 87 through gears actuator and valve linkages 91 to move the ahead steam valve 89 in the direction indicated by the reference power response to establish a corresponding steam fiow rate to produce the desired power response from the steam turbine 93. Potentiometer 85 is connected to sense the position of the ahead steam valve 89 and applies a signal to the ahead summing amplifier 81 indicating the position of the ahead steam valve 89. The summing amplifier 81 compares the reference power response signal from the function generator 79 and the feedback signal from the valve position sensor 85 and applies the difference as an error signal to the ahead SCR motor control 83 causing the pilot motor 87 to move the valve in the proper direction. When the valve has moved to the position called for by the reference from the function generator 79, the pilot valve motor 87 is stopped because the feedback signal from the valve position sensor 85 cancels the reference signal from the function generator 79.

If the throttle lever 23 in FIGURE 2 is moved to a new position, the control circuit described will act to move the steam valve 89 to a new corresponding position with a resultant change in turbine power response and the ships speed.

The ahead rate adjust circuit controls the maximum amount of current which may flow through the armature of the ahead pilot motor 87 and may be adjusted to provide the desired rate adjustment.

There is also a throttle lever in the engine room which may be used to control the power response of the steam turbine 93 corresponding to the throttle lever 23 on the bridge console. An engine room throttle potentiometer 71 in FIGURE 3 produces a corresponding reference to con trol the power response in the same manner described for the bridge throttle.

A corresponding control circuit is provided to control the astern power response of the steam turbine 93. The power response signal from the engine room throttle potentiometer 71 or from the bridge throttle potentiometer 73 is applied to the function generator 79. The ahead signal from the

potentiometers

71 or 73 was negative for the ahead direction and is positive for the astern direction.

The positive reference signal from the function generator 79 is amplified by the astern summing amplifier 101 and applied to the astern SCR motor control 105 causing pilot motor 107 to move the astern steam valve 111 in the direction indicated by the reference to establish a corresponding steam flow rate in the astern section of the steam turbine 93. Potentiometer 103 is connected to sense the position of the astern steam valve 111 and applies a signal to the astern summing amplifier 101 indicating the position of the astern steam valve 111. The summing amplifier 101 compares the reference power response signal from the function generator 79 and the feedback signal from the valve position sensor 103 and applies the difference as an error signal to the astern SCR motor control 105 causing the pilot motor 107 to move the astern valve 111 in the proper direction to establish the proper steam flow. When the valve has moved to the position called for by the reference from the function generator 79, the pilot motor 107 is stopped because the feedback signal from the valve position sensor 103 cancels the reference signal from the function generator 79.

In this particular embodiment the propeller speed may be used as a feedback by closing the selector switch 135, energizing coil 137, closing normally

open contacts

139 and 141. This may be termed the maneuvering mode of operation in this particular embodiment. When the throttle lever 23 is moved to the stop or astern position from the ahead position, the relay coil 137 is automatically energized to apply the speed feedback from the propeller. The speed feedback provides a faster and more accurate indication of the propeller speed including cavitation effects.

When the ship is to be slowed down or stopped, the throttle lever 23 on the bridge console 18 in FIGURE 2 is moved rapidly from the ahead position to the stop position, reducing the reference signal from the bridge throttle 73 in FIGURE 3 to zero. The feedback signal from the propeller shaft feedback tachometer 127 indicates that the propeller 131 is still rotating due to inertia. The ahead steam valve 89 is closed and the astern steam valve 111 is opened, allowing steam to enter the astern section of the steam turbine 93 to turn the propeller in the astern direction. The application of steam to the astern section of the turbine in this manner is termed bursting. The astern steam valve 111 is then closed. Momentum will continue to carry the ship forward in the water, causing the propeller 131 to rotate in a forward direction due to the drag of the water. The speed feedback tachometer 127 applies a signal back causing the astern steam valve 111 to open again for a short period of time rotating the propeller in the astern direction. The throttle lever 73 remains in the stop position and an error signal from the comparison of the speed feedback signal from the tachometer 127 and the function generator 79 closes the astern steam valve 111. This continues until the ships momentum in the water is reduced so that the propeller 131 will not rotate due to drag.

' The control of the steam valves 89 and 111 may be removed from automatic control by closing

contacts

97 and 115 and opening

contacts

99 and 117. The pilot motors may be directly operated then by signals applied directly to the

pilot motors

87 and 107.

The automatic control of the throttles may be transferred between the bridge and engine room by closing the appropriate contacts 75 and 77.

A pressure transducer is used to measure the steam pressure of the steam turbine. If the pressure in the steam turbine 93 falls below a safe level, the low pressure amplifier 143 applies a signal to the ahead summing amplifier 81 and the astern summing amplifier 101 to limit the signal from these amplifiers and thus limit how far the ahead steam valve 89 and the astern steam valve 111 opened. It the steam pressure continues to fall, the low pressure signal amplifier 143 overrides the signals from the function generator 79 and the feedback signals to close the ahead steam valve 89 and the astern steam valve 111.

Throttle transfer control Refer now to FIGURE 4 for a description of the throttle transfer control. Assume that the engine room is transferring the control of the turbine to the bridge. To accomplish this,

transfer switch contact

201 and 203 must be closed. An alarm bell 205 is energized through normally closed contact 207A of the bridge control auxiliary relay. To stop the alarm the bridge operator must depress the acknowledge pushbutton 209, which allows current to flow from the common bus 211 through transfer switch contact 201, through normally closed contact 213A of the throttle match relay, through coil 207 of the bridge control auxiliary relay, and through coil 215 of the bridge control relay, into negative bus 212. The bridge control relay and the bridge control auxiliary relays now pick up and normally closed contact 207A now opens and disconnects the alarm bell from the circuit. Normally open contact 207B of the bridge control auxiliary relay closes as the relay picks up and allows current to continue to pass through bridge-control auxiliary relay coil 207 after acknowledge pushbutton 209 has been released, thus sealing the relay in. Normally open contact 207C of the bridge control auxiliary relay is now closed and allows the alarm bell to be energized when one of the following conditions exists: (1) when normally open contact 439A of the shaftstop relay 439 is closed due to the propeller shaft NOT having been rotated for three minutes, and (2) when the bridge engine order telegraph is moved from its standby or bridge control position, which causes contact 219A to close.

Throttle malfunction of the bridge throttle assembly causes normally open contact 221A of the throttle failure relay to close, thus completing the circuit to the alarm bell 205, energizing the bell.

The transfer from the engine room to the bridge cannot take place when the engine room throttle position and the bridge throttle position do not match. Indicating meters may be used instead of the described interlocking. In FIGURE 5 potentiometer 301, which is mounted on the engine room throttle lever assembly, is connected at one side to negative 50 volt bus 303 and on the other side to positive 50 volt bus 305. Point A which is a center tap of the potentiometer is connected to the common bus 211, thereby stabilizing point A at zero volt potential with respect to the 50 volt positive and

negative busses

305 and 303 respectively.

The potentiometer wiper connection 307 is connected to one side of potentiometer 309.

The bridge potentiometer 311 is connected in a similar manner as described above with the positive and

negative busses

305 and 303 respectively connected to either side of the potentiometer and a center tap, point B, connected to the common bus 211 to stabilize point B at zero volt potential with respect to the positive and negative busses 205 and 303 respectively. The bridge potentiometer wiper connection 313 is connected to the other side of potentiometer 309. Potentiometer 309 acts as a voltage divider, balancing a voltage from potentiometer 301 against an equal voltage from potentiometer 311.

During installation the wiper of potentiometer 309 is adjusted so that the potential of the wiper connection 313 is at zero volts with respect to the positive and

negative busses

305 and 303 respectively, and throttle match relay coils 223 and 225 remain dropped out in their normal positions. If, however, the engine room throttle position is different from the bridge throttle position at the time when the transfer is to be made, the voltages from

potentiometers

301 and 311, as applied to potentiometer 309, are different. This causes a current to flow from the wiper connection 313 of potentiometer 309, through adjustable resistor 315, and energize one of the throttle match relay coils 223 or 225, depending on the polarity of the current which is applied. If, for example, the current is positive with respect to the common bus 211, relay coil 225 will be energized and normally open contact 225A, in FIGURE 4, will close, energizing coil 213 of the throttle match auxiliary relay, and opening normally closed contact 213A. This prevents the transfer from being made. Similarly, if the current from potentiometer 309 is negative, the throttle match relay coil 223 is energized and normally open contact 223A of the throttle match relay will close, causing coil 213 of the throttle match auxiliary relay to be energized and open normally closed contact 213A, and thereby preventing the transfer from being made.

With the engine room in control of the turbine, the bridge throttle control lever assembly must be oriented in the OFF position and cam switch contact 227 is then open. However, if the bridge throttle lever is moved away from the OFF position, either in the ahead or in the astern direction, cam switch contact 227 closes and allows current to flow through normally closed contact 207A and energize the alarm bell 205.

Normal and maneuvering mode control The mode selector switch, located on the engine room console, is used to select the normal or maneuvering .modes of operation. As the name implies, the normal mode usually will be used when steaming at sea. In the normal mode, the sea scoop is open, the circulating pump is stopped, the astern guard valve is closed and there is no speed feedback error signal applied to the throttle control regulator. The maneuvering mode is used for slow, stop or astern operations, or where speed feedback error signals are necessary.

In going to maneuvering mode the mode selector switch is turned to the maneuvering mode position, closing contact 235 in FIGURE 4 and energizing the closing coil 239 of the maneuvering mode relay. This closes normally open contact 239A, which energizes coil 241 of the auxiliary maneuvering mode time delay relay and coil 243 of the auxiliary maneuvering mode relay through normally closed contact 249B of the automatic maneuvering mode relay. Normally

open contacts

243A, 243B, and 243C now close for a period of one second to start the main circulating pump (not shown), to open the sea water inlet valve (not shown), to open the astern guard valve (not shown). The auxiliary maneuvering mode time delay relay times out after one second, which causes contact 241A to open and de-energize auxiliary maneuvering relay coil 243, opening

contacts

243A, 243B, and 243C.

When closing, coil 239 of the maneuvering mode relay is energized, normally open contact 239B is closed and energizes the coil 245 of the speed feedback relay.

Automatic switching to the maneuvering mode occurs when the throttle lever is moved to the stop or astern position while the mode selector switch is in the normal position. Cam switch 247 closes in these positions and closing coil 249 of the automatic maneuvering mode relay is energized. This closes normally open contact 249A and energizes coil 239 of the maneuvering relay, which results in an operation in a similar manner as described previously. When cam switch 247 closes, coil 251 of the auxiliary automatic maneuvering relay is energized and closes normally open contact 251A, allowing

coils

241 and 243 to be energized while normally closed con-tact 2493 of the automatic maneuvering mode relay is open.

When automatic switching occurs and coil 249 of the automatic maneuvering mode relay is energized, the relay is latched in the energized position by mechanical means and can not be reset until the mode selector switch contact 233 is closed by selection of the maneuvering mode of the mode selector switch. When this selection is made and contact 233 closes, current will pass from the common bus 211 through contact 233 and through normally open contact 249C of the automatic maneuvering mode relay and energize trip coil 250, thus resetting the automatic maneuvering relay.

Cam switch 248 on the bridge throttle lever operates in a similar manner as described above and is placed in the circuit by energizing the bridge control relay coil 207 which then opens contact 207D and closes contact 207E, as described in the throttle transfer control portion of this description.

Direction relays Normally open contact 207F and normally closed contact 2076 of the bridge control auxiliary relay in FIG- URE 4 change state when the responsibility of the turbine is transferred from the engine room to the bridge. With normally closed contact 207G closed, the engine room throttle is in command; and when the throttle lever is moved in the ahead direction, contact 263 closes and allows current to pass from the common bus 211 through normally closed contact 207G of the bridge control auxiliary relay through normally closed contact 255D of the astern direction relay and energize the coil 259 of the ahead direction relay which then picks up and opens normally closed contact 259D, preventing the accidental completion of the astern direction relay coil 255.

Similar action results from moving the throttle in the astern direction, in which case throttle lever contact 265 closes and permits current to pass from the common bus 211 through normally closed contact 2076, through normally closed contact 259D and energize astern direction coil 255, which picks up and opens normally closed contact 255D, thus preventing accidental pickup of the ahead direction relay coil 259.

Both the astern and ahead direction relays have additional normally closed contacts in the speed feedback circuit, where their functions are described under Speed Feedback Control.

Zero shaft speed detector In FIGURE 6, terminal B of static limit switch 401 is connected to the negative 18 volt bus 18N and to the one side of timer relay contact 403, having motor 405 close contact 403 once during each one minute cycle. Terminal R of static limit switch 401 is connected to the positive 6 volt bus GP and to terminal F of AND/NOT circuit 409. This positive voltage as applied to the AND/ NOT circuit 409 is equivalent to a ZERO signal.

Terminal W of static limit switch 401 is connected through resistor 407 to negative voltage bus 18N and to terminal K of AND/NOT circuit 409. The static limit switch operates in such a manner that when a metal object passes within its proximity its terminal W is temporarily connected to terminal B, which thus acquires a negative polarity of 18 volts, changing the signal applied to terminal K of the AND/ NOT circuit 409 from a ZERO to a ONE.

The ZERO signal, which is produced from output terminal E of AND/ NOT circuit 409, changes to a ONE signal when ZERO signals are applied to both input terminals K and F. The change, however, may not be abrupt enough to be applied to the counter circuit 413 and is therefore first applied to trigger circuit 411, terminal Y. When the ONE signal is applied to terminal Y of trigger circuit 411, a ZERO signal is produced from its output terminal W and applied to the PUL terminal of counter bit 413. This positive going pulse causes the counter bit 413 to change its state so that a ZERO signal is now produced from terminal E. As the output from terminal E of counter 413 changes from a ONE signal to a ZERO signal and is applied to the PUL terminal of counter bit 415 as a positive going pulse, the state of counter bit 415 also changes and now produces a ONE signal from terminal W which is applied to terminal X of AND/ NOT circuit 417.

The next operation of static limit switch 401 again causes the output terminal E of AND/NOT circuit 409 to produce a positive going pulse which is applied to the PUL terminal of counter bit 413, again changing its state. Terminal L now produces a ZERO signal which is applied to terminal Y of AND/NOT circuit 417. With the next pulse, counter bit 413 again changes its state, which causes a positive going pulse to be applied to the PUL terminal of counter bit 415, causing it to change its state and produce a ZERO signal from its output terminal W which is applied to terminal X of AND/ NOT circuit 417. When counter bit 413 changed state, its ZERO signal from output terminal L changed to a ONE signal, which again changes to a ZERO signal with the next pulse from the static limit switch. AND/NOT circuit 417 now has two ZERO signals applied to its input terminals X and Y, which causes AND/NOT circuit 417 to produce a ONE signal from its output terminal Z. This negative going pulse is applied to terminal R of ONE SHOT circuit 419, which produces a momentary ONE signal from its output terminal P.

The above shows that three pulses produced by the static limit switch will produce one pulse from the ONE SHOT 419. This is to accommodate the gear ratio between the ships propeller shaft and the tachometer which supports the actuator for the static limit switch and produces three pulses for each revolution of the propeller shaft.

Timer motor 405 causes contact 405 to close momentarily once per minute, thus applying a ONE signal to input terminal H of trigger circuit 421, which produces a positive going pulse from its output terminal L and applies this to terminal M of ONE SHOT circuit 423. ONE SHOT circuit 423 then produces a ONE pulse from terminal E and applies this to terminal M of AND/ NOT circuit 425.

Assuming now that counter bit 427 and counter bit 429 have been reset, then the output from terminals L and W of

counter bits

427 and 429 are both ONE and applied to input terminals X and Y of AND/NOT circuit 431, causing AND/NOT circuit 431 to produce a ZERO signal, which is applied to terminal N of AND/NOT circuit 425.

When the output of terminal E of ONE SHOT 423 momentarily changes from a ZERO to a ONE and back, it causes AND/NOT circuit to change its output from terminal L from a One to a ZERO. This positive going pulse is applied to the PUL terminal of counter bit 427, changing its state, so that the output from terminal E is now a ONE and the output from terminal L changes to a ZERO, which is applied to terminal Y of AND/NOT circuit 431.

The next pulse from trigger 421, as caused by the closing of contact 403, again causes the ONE SHOT 423 to fire and AND/NOT circuit 425 to produce a positive going pulse, which is applied to counter bit 427 causing it to change state. When the output of terminal E changes from a ONE to a ZERO and applies this positive going pulse to the PUL terminal of counter bit 429, counter bit 429 changes state and applies a ONE signal from terminal P to the input terminal L of amplifier 432. This causes alarm relay 435 to pick upand close contact 435A in FIGURE 4, which then allows power to be supplied to shaft stop indicating light 229.

In FIGURE 6, contact 403 closes again one minute later and causes through the trigger 421, ONE SHOT 423, and AND/NOT circuit 425, a positive pulse to be applied to counter bit 427 which changes state and causes the output of terminal L to change from a ONE to a ZERO, which is applied to terminal Y of AND/ NOT circuit 431. With two ZERO signals applied to input terminals X and Y, AND/ NOT circuit 431 produces a ONE signal from its output terminal W which is applied to amplifier 437, causing shaft stop relay 439 to pick up and 10 close contact 439A in FIGURE 4, causing the alarm bell 205 to ring.

The ONE signal is also applied to terminal N of AND/NOT circuit 425, and thus prevents future pulses to be applied to counter 427, and thus prevents counter 427 from changing its state.

However, if the propeller shaft is rotated at least one revolution per minute, the positive going pulses from ONE SHOT 419 applied to terminals RST of

counter bits

427 and 429 will reset the counters once each minute, and thus counteract the pulses applied to the PUL terminals of the

counters

427 and 429 and prevent them from changing state, and consequently preventing the

relays

435 and 439 from picking up.

Speed-feedback control Throttle lever potentiometers 501 and 503 (in FIG- URE 7) located in the engine room and on the bridge respectively, are connected on either end to the positive and negative 50 volt busses 305 and 303, respectively. A center tap C and D of each of the potentiometers is connected to the common bus 211, thereby stabilizing points C and D at zero volt potential with respect to the 50 volt positive and negative busses. The potentiometer wiper connection of the engine room potentiometer 7501 is connected to normally closed contact 215A of the bridge control relay while the wiper connection of the bridge throttle potentiometer 503 is connected to the normally closed contact 215B of the bridge control relay.

The bridge control relay, which is energized when control responsibility of the turbine is transferred from the engine room to the bridge, connects either the engine room throttle 501 or the bridge throttle potentiometer 503 in the circuit. Normally closed contact 215A of the bridge control relay is connected to the input terminal R of the function generator 502 and through resistor 504 to rheostat 525, applying the reference signal to the speed feedback amplifier 511. Tachometer 505 is connected to one side of each of

potentiometers

507 and 509 of which the other sides are connected to the common bus 211. Each of the potentiometers 507 and 509' acts as a voltage divider and provides an adjustable voltage input to the ahead and astern

speed feedback amplifiers

511 and 513, respectively.

The slider connection of potentiometer 507 is connected to normally closed contact 259A of the ahead direction relay and is connected through resistor 521 to rheostat 523. Normally closed contact 259A of the ahead direction relay is connected through normally closed contact 255A of the astern direction relay to one side of resistor 519.

Rheostats

525 and 523 and resistor 519 are on one side connected together, and to terminal R of speed-feedback amplifier 511, and through resistor 527 to one side of rheostat 529. Terminals A, E and C of speed feedback amplifier 511 are connected to the 50 volt positive bus 305,

common bus

211 and 50 volt negative bus 303, respectively.

The speed feedback amplifier 511 is an operational amplifier and operates in a manner which is well-known to those skilled in the art. In the operation involved here, the output of throttle potentiometer 501, through resistor 504, and rheostat 525, is applied to the input of the operational amplifier 511 as a reference signal, where it is compared to the signal produced by the feedback output of the tachometer 505. The resultant of this comparison is fed through resistor 527 and then through rheostat 529 as an output of the operational amplifier. The signal is applied tonormally open contact 245A of the speed feedback relay which is energized when the maneuvering relay coil 239 (FIGURE 4) is energized. Normally open contact 245A of the speed feedback relay is connected to normally closed contact 255B of the astern direction relay and to normally open contact 535 of the astern valve closed limit relay.

The astern valve closed limit relay is energized when the astern valve is closed, and consequently normally open contact 535 of the astern valve closed limit relay closes when the astern valve is closed, and thus provides for completion of the circuit between the ahead speed feedback amplifier 511 and the ahead summing amplifier (operation shown later).

The astern direction relay contact 255B closes when the throttle lever is moved to the stop position, as described above.

The astern speed feedback amplifier circuit operates in a similar manner to the ahead speed feedback circuit with throttle lever potentiometer 501, establishing the reference signal, which is applied through resistor 551 to rheostat 553, and with tachometer 505 applying the feedback signal to one side of potentiometer 509, which is on the other side connected to the common bus 211. The slider connection of potentiometer is connected through resistor 547 to rheostat 549 and to normally closed contact 259C of the ahead direction relay which is connected to normally closed contact 255C of the astern direction relay, which in turn is connected to resistor 545. The other side of

rheostats

553 and 549 and of resistor 545 are connected together and to the input terminal R of the astern speed feedback amplifier 513 and through resistor 555 to rheostat 557.

Terminals A, E, and C of speed feedback amplifier are connected to the 50 volt positive bus 305, the common bus 211 and the 50 volt negative bus 303, respectively. The output of the operational amplifier from terminal I is applied to the normally open contact 245B of the speed feedback relay and to resistor 559, which are connected together and to the common bus 211.

Normally open contact 561 of the ahead valve closed limit relay is closed when the ahead steam valve is closed and completes the circuit between the astern speed feedback amplifier and the astern summing amplifier. The ahead direction relay contact 259B closes when the throttle lever is moved to the stop position, allowing the signal from the speed feedback amplifier to be applied to the summing amplifier.

' Sensitivity of the speed feedback amplifier is greatly increased when the throttle lever is moved to the stop position. Under this condition the ahead and astern direction relays are de-energized and nor-mally

closed contacts

259A and 255A of the ahead and astern direction relays, respectively, are closed and pass current through resistor 519, thus setting up a parallel resistance path, which has a ratio of approximately 30:1 with the resistance path consisting of resistor 521 and rheostat 523.

The reference input to the speed feedback amplifier is at ZERO due to the position of the throttle, and a large current from the speed feedback tachometer is now applied to the speed feedback amplifier as a positive feedback signal. The speed feedback amplifier compares these signals and produces a negative error signal which is applied to the summing amplifier and which causes the ahead steam valve to close.

When the ahead steam valve is closed normally open contact 561 of the ahead valve closed limit relay is also closed and allows a signal from the astern speed feedback amplifier to be applied to the astern summing amplifier. This signal is caused by the propeller which is still rotating in the ahead direction due to drag in the water caused by the momentum of the ship. As the propeller rotates, so does the speed feedback tachometer 505 which then produces a positive signal through rheostat 509, normally closed

contacts

259C and 255C of the ahead and astern direction relays, respectively, and through resistor 545, and applies this signal to astern speed feedback amplifier, which in turn produces a negative signal which is applied to the astern summing amplifier, causing the astern steam valve to open. This causes the propeller to stop, at which point the tachometer signal is reduced to zero; and consequently the signal from the speed feedback amplifier is reduced to Zero. The circuitry of the summing amplifier is so that a zero signal from the speed feedback amplifier will cause the astern steam valve to close, as is discussed later.

If the momentum of the ship is such that the propeller will again begin to rotate, an error signal is again produced by the speed feedback tachometer which will cause the astern steam valve to open and repeat the process until the ship has come to a complete standstill.

Summing amplifiers In FIGURE 1, the ahead summing amplifiers 81 and the astern summing amplifier 101 accept signals from the function generator 179, the ahead and astern speed feedback amplifiers 129 and 130, the ahead and astern steam valve position sensors 35 and 103, and the low steam pressure amplifier 143. The sum of these signals, considering positive and negative values, determines the output voltage of the summing

amplifiers

81 and 101. The summing amplifiers invert the sum of the applied signals; and therefore if the sum of the applied signals is positive, the output of the amplifier will be negative.

A negative output of the ahead summing amplifier tends to open the ahead steam valve while a positive output tends to close it. The opposite is true of the astern amplifier where a positive output from the amplifier tends to open the astern steam valve while a negative output tends to close it.

The zero adjust function positions the steam valves near the crack point, which is that position of the steam valve where all the mechanical tolerances have been taken up; and if the valve is opened a fraction farther, steam will be allowed to flow into the turbine. Zero adjust occurs when the throttle lever is off the stop position, producing either a positive or negative signal which is summed with the valve position feedback voltage.

The steam valve close adjustment positions the steam valve well into the closed position, when the throttle lever is in the stop position or in the position calling for the opposite valve to open.

The low steam pressure signal applied to the ahead summing amplifier is a negative signal supplied by the low steam pressure amplifier (not shown) which must cancel out the positive voltage of the function generator which causes the negative signal from the valve position sensor to be the only effective input to the ahead summing amplifier. This negative signal is inverted and is applied to the steam valve circuitry as a positive signal, causing the ahead steam valve to close.

If the low steam pressure signal does not call for a complete valve closing, its negative voltage will cancel only part of the function generators positive signal While the remainder of the function generator signal is canceled out by the negative signal from the valve position sensor, which means that the steam valve will position itself somewhere between fully open and totally closed, depending on the relative magnitude of the low steam pressure signal.

The low pressure signal which is applied to the astern summing amplifier operates in a similar manner except that the signal from the low steam pressure amplifier is now a positive signal so that it may cancel out the negative voltage signal produced by the function generator, which causes the positive symbol of the astern steam valve position sensor to be the only effective input to the astern summing amplifier. This positive symbol is inverted by the summing amplifier and applied to the astern steam valve circuitry (not shown) and causes the astern steam valve to close.

If the low steam pressure signal is not calling for a complete valve closing, its positive voltage will cancel only part of the function generators negative signal while the remainder of the function generator signal is canceled out by the positive signal from the astern valve position sensor, which means that the valve will position itself somewhere between fully open and totally closed, depending on the relative magnitude of the low steam pressure signal.

Function generator In FIGURE 8, the throttle lever potentiometer 603 represents both the engine room and the bridge throttle potentiometers.

The wiper connection 601 of throttle potentiometer 603 is connected to point B, which in turn is the junction point of the cathodes of

diodes

605 and 607 and the anode of diode 609.

The cathode of diode 609 is connected through rheostat 611 to the negative 50 volt bus 50N and to resistor 613 and the cathode of diode 615. The anode of diode 615 is connected through rheostat 617 to junction point F, which is the junction point for the connections to rheostats 618- 627 and connects to the input terminal R of operational amplifier 629.

This high gain operational amplifier is used for signal amplification. When analyzing the electrical characteristics of operational amplifier 629, it is sufiiciently accurate to assume that the input signal voltage (the voltage at point F and terminal R) of the operational amplifier never deviates from zero volts with respect to common bus 211. Thus, the gain of the amplifier is determined directly by the ratio of the feedback resistance to the input resistance.

The operational characteristics of the function generator for the ahead direction is described as follows. Assume that the throttle lever is initially in the STOP position so that no voltage signal is applied to the function generator. When the throttle lever is moved slightly in the ahead direction, the reference output voltage of the throttle lever potentiometer which is applied to point E becomes negative with respect to common bus 211. Current now flows from the operation 1 amplifier input terminal R, through junction point P, rheostat 617 and diode 615 to point G, and the negative 50 volt bus 50N. This current produces a positive voltage output from the operational amplifier 629, which in magnitude is directly proportional to the increasing negative reference voltage from the throttle lever potentiometer, thus establishing the first slope of the function generator characteristic.

The constant current circuit consists of resistor 613 connected in series with series connected potentiometers 631-637. Potentiometer 637 is connected through resistor 641 to the collector of transistor 643 of which the emitter is connected to rheostat 645, which is connected to the positive 50 volt bus 50P.

Zener diode 647 connected to the anode of diode 649 has its cathode connected to the positive 50 volt bus 50P. The cathode of diode 649 is connected to the base of transistor 643 and through resistor 651 to the common bus 211, thus forming the firing circuit for transistor 643, which then passes one milliamp constant current through potentiometers 631-637 and resistor 613, and in doing so establishes a fixed voltage drop across each of the potentiometers 631637.

As the reference voltage increases, due to repositioning of the throttle lever potentiometer, in the negative direction, a point is reached where the voltage level of point H goes negative with respect to the input terminal R of the operational amplifier 629, causing additional cur rent to flow through point H in the second path, consisting of rheostat 618 connected in series with diode 653, the cathode of which is connected to the wiper connection of potentiometer 631. There are now two parallel paths for the input current, causing a change in the ratio of feedback resistance to input resistance and thus establishing a new slope in the function generator output.

As the reference voltage increases farther in the negative direction, a third parallel path through rheostat 619 and diode 655 which has its cathode connected to the wiper connection of potentiometer 632, allowing additional current to pass through points I and H which again change the ratio of the feedback resistance to the input resistance thus establishing a third slope for the characteristics of the function generator. FIGURE 9 is a graphic representation of these characteristics of the function generator showing the slopes represented by the odd numbers and the breakover points represented by the even numbers. Thus, slope 701 is established by the ratio of the feedback resistance of rheostat 617 (in FIGURE 18) when at point 702 (in FIGURE 9) the second cunrent path is established through rheostat 618 and diode 653 (in FIGURE 8) which changes the slope of curve to 703 (in FIGURE 9).

As the throttle lever is moved farther in the ahead direction, causing the reference voltage to constantly increase in the negative direction, the slope changes with each consecutive breakover point until the throttle lever is in the full ahead position, at which point all the rest of the parallel circuits consisting of rheostat 620 connected to the anode of diode 657 'which has its cathode connected to the wiper connection of potentiometer 633, parallel circuit with rheostat 621 connected to the anode of diode 659 which has its cathode connected to the wiper connection of potentiometer 634, parallel circuit with rheostat 622 connected to the anode of diode 661 which has its cathode connected to the wiper connection of potentiometer 635, parallel circuit with rheostat 623 connected to the anode of diode 663 which has its cathode connected to the wiper connection of potentiometer 636, and parallel circuit with rheostat 624 connected to the anode of diode 665 which has its cathode connected to the wiper connection of potentiometer 637, are connected in the feedback circuit.

In FIGURE 9, point 704 is the breakover point when the fourth parallel circuit establishes slope 705, until at point 706 the fifth parallel circuit establishes slope 707, and at point 708 the sixth parallel circuit establishes slope 709, and at point 710 slope 711 is established by the seventh parallel circuit, when finally at point 712 slope 713 is established by the eighth parallel circuit. Thus, the breakover points are determined by the setting of potentiometers 631-637 and the slope of gain of the function generator beyond each breakover point is determined by the setting of the associated rheostats 617-624.

The astern characteristic is established whenever the throttle lever is moved in the astern direction, thus producing a positive reference signal which is similar to those of the ahead characteristics, and as in the ahead direction slopes and breakover points are established by the various parallel paths of the feedback circuits. Thus, the parallel circuit consisting of potentiometer 638 which has its wiper connection connected to the anode of diode 667 of which the cathode is connected to rheostat 62-5 (in FIGURE 8.) produces slopes 721 (in FIGURE 9) when the throttle lever is slightly moved in the astern direction. As the throttle is continued to be moved in the astern direction, point P becomes positive with respect to the positive voltage of the input terminal R of the operational amplifiers 629, causing a second parallel circuit to be established. The new circuit consists of potentiometer 639 with its wiper connected to the anode of diode 669, which has its cathode connected to rheostat 626.

In FIGURE 9, the breakover to the second parallel circuit is represented by point 722, at which time slope 723 is established. Breakover point 724 indicates the establishment of slope 725 which is caused by the third parallel circuit consisting of potentiometer 640 with its wiper connection connected to the anode of diode 671 which has its cathode connected to rheostat 627 in FIG- URE 8. The astern constant current circuit consists of rheostat 673, which on one side is connected to the positive 50 volt bus 50F and on the other side is connected to the anode of diode 605 and the anode of diode 607 and through resistor 675 to the series connected

potentiometer

638, 639 and 640, which are connected to one side of resistor 677. The other side of resistor 677 is connected to the collector of transistor 679- of which 15 the emitter is connected through resistor 681 to the negative 50 volt bus SON. The common bus 211 is connected through resistor 68 7 to thebase of transistor:679 and to the anode of diode 685 of which the cathode is connected to the cathode of the Zener diode 683. The negative 50 volt bus is connected to the anode of Zener diode 683.

Rheostat 681 is set so that a consant current of one m-illiamp passes through the constant current circuit. The slopes or gain of the function generator can be changed so that the function need not be a cube, which is the case with the astern direction.

While the invention has been explained and described with the aid of particular embodiments thereof, it will be understood that the invention is not limited thereby and that many modifications restaining and utilizing the spirit thereof without departing essentially therefrom will occur to those skilled in the art in applying the invent-ion to specific operating environments and conditions. It is therefore contemplated by the appended claims to cover all such modifications as fall Within the scope and spirit of the invention.

What is claimed is:

1. A ship comprising a propeller, a propulsion unit connected to said propeller for rotating said propeller and providing power for said ship, means for presetting a reference power response for said propulsion unit, means for measuring the speed of rotation of said propeller to indicate the power response of said propulsion unit, means for comparing the measured and reference power response of said propulsion unit, means responsive to a predetermined power response reference'and said measuring means for reversing the power response of said propulsion unit for a predetermined period of time to reverse the direction of rotation of said propeller.

2. A ship having a steam turbine as a propulsion unit for said ship, a propeller connected to said steamiturbine, means for presetting a reference propeller speed for said steam turbine, means for measuring the speed of rotation of said propeller, means for comparing the speed of rotation of said propeller and the reference propeller speed, means responsive to said comparing means for controlling said steam turbine to bring the speed of rotation of said propeller towards the reference power response, means for removing said reference propeller speed, and means responsive to the removal of said reference propeller speed and said speed of rotation of said propeller to apply reverse torque to said propeller.

References Cited UNITED STATES PATENTS 2,827,910 3/1958 Wells et al. l37-30 3,233,412 2/1966 Wagner 60-105 X 3,295,320 1/1967 Takeda et al. 60-102 X ANDREW H. FARRELL, Primary Examiner.