Fuel trim system for multiple drive propulsion systems

Description

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates generally to equipment used for monitoring the efficiency and improving the fuel consumption of marine vessels with multiple drive propulsion systems.

(2) Description of the Prior Art

Traditional systems for conserving fuel on commercial vessels require the vessel's engineer to manually measure the fuel level in the ship's tank(s) in order to determine the amount of daily fuel consumption. This information is recorded in the ship's log along with engine rpm and engine exhaust temperatures.

Accordingly, the ship's master records the vessel's course, distance traveled, weather and sea conditions. All the recorded data is then forwarded to a port engineer who determines the most efficient vessel speed and/or engine rpm for a given course under similar conditions.

Automated versions of the above method monitor the vessel's fuel consumption via flow meters and the vessel's speed via a global positioning system and utilize a computer software program for calculating and recording miles per gallon of fuel consumed. The computer program also calculates and records the most efficient running speed for the vessel and the speed required for achieving its estimated time of arrival. The information is made available to the vessel's operator via a display screen.

The present invention uses a computer program and components similar to those described above to monitor fuel and vessel speed. In addition, sensors are added to measure the thrust forces developed by each of the ship's propellers. Given that the drive systems fuel efficiencies are rarely matched for a given engine rpm, there exists an opportunity to conserve fuel by comparing the thrust produced to the gallon of fuel consumed by each system and prompting the vessel's operator to make the proper throttle adjustment for each drive system to insure that the system with the best thrust to fuel ratio makes the largest contribution to the total thrust force required to maintain vessel speed.

SUMMARY OF THE INVENTION

Accordingly, a first object of this invention is to provide a system for minimizing marine vessel fuel consumption while maintaining a predetermined steady state speed.

Another object of this invention is to monitor the fuel consumption of each of the vessel's drive systems at a steady state speed for the purpose of identifying the individual fuel consumptions relative to the total fuel being consumed by the vessel propulsion system.

Yet another object of this invention is to monitor the thrust force generated by each of the vessel's drive systems at a steady state speed for the purpose of identifying the individual thrust forces relative to the total thrust force being supplied by the vessel's propulsion system.

A further object of this invention is to monitor the engine speed of each of the vessel's drive systems for displaying the vessel steady state speed.

Another object of this invention is to calculate the fuel consumption to thrust ratio of each of the drive systems at the vessel steady state speed.

Still another object of this invention is to prompt the operator via an interactive display to adjust the vessel throttles in such a manner as to cause the drive system with the most efficient fuel to thrust ratio to provide the largest contribution to the total thrust required for maintaining the vessels steady state speed.

Another object of the invention is to display the percentage of fuel and/or the amount of fuel being saved as a result of an operator making the suggested throttle adjustments.

In view of these objects, the instant invention provides an apparatus for conserving fuel based on the overall efficiency of the vessel while it is operating at a predetermined steady state speed. The system comprises of fuel flow meters in the engine supply lines and thrust sensors attached to the driveline or propeller shaft. The system also includes tachometers to measure the rotational speed of the engines and a global positioning system for determining the vessel speed. All data is acquired by a microprocessor, which calculates the drive system efficiencies and communicates the results to an operator display. The display prompts the operator to adjust the throttles to minimize fuel consumption while maintaining vessel speed. All acquired data in recorded for further analysis by port engineers.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a plan view of a typical vessel powered by two (2) drive units with the apparatus of the present invention installed;

FIG. 2 illustrates a display for displaying the performance of the vessel and for prompting the operator to make specific throttle adjustments for the purpose of minimizing total fuel consumption;

FIG. 3 illustrates a computer program in ladder logic format for operation of the system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to drawing FIG. 1, there is generally indicated at 1 a vessel with a propulsion system consisting of drive unit 2 and drive unit 3. The drive unit 2 consists of an engine 7 that transmits power via driver shaft 11 to the driven load generally indicated at 13. The driven load 13 is further defined as a propeller, wheel or any such device that is capable of converting the torsion force of the driver shaft 11 to a thrust force for propelling the vessel 1. Similarly, drive unit 3 consists of an engine 8 that transmits power via drive shaft 12 to the driven load 14.

Thrust sensors indicated at 9 and 10 measure the thrust induced in driver shafts 11 and 12 and are in electrical communication with microprocessor 4 via lines 20 and 21.

Tachometers indicated at 16 and 17 sense the rotational speed of engines 7 and 8 and are in electrical communication with microprocessor 4 via lines 20 and 25.

Flow meters indicated at 18 and 19 measure the fuel consumption of engines 7 and 8 and are in electrical communication with microprocessor 4 via lines 21 and 24.

A global positioning system 6 track the speed, heading and instantaneous position of the vessel 1 and is in electrical communication with microprocessor 4 via line 26.

Further indicated is a display module 5 located at the operator control station of vessel 1 and is in electrical communication with microprocessor 4 via line 27.

The microprocessor 4 can be chosen from any of the well-known computers, which are designed for data acquisition, storage, display. Data acquisition software is employed to read the data, perform the mathematical calculations and execute the program.

Referring now to drawing FIG. 2, there is illustrated a frontal view of display module 5. A digital engine 7. Another indicator light 28 located on digital display 5 prompts the vessel 1 operator to indicator light 29 located on digital display 5 prompts the vessel 1 operator to increase the RPM of decrease the RPM of engine 7. Likewise, a digital indicator light 30 located on digital display 5 prompts the vessel 1 operator to increase the RPM of engine 8. An indicator light 31 located on digital display 5 prompts the vessel 1 operator to decrease the RPM of engine 8. A digital readout V located on digital display 5 indicates the vessel 1 speed over ground. Another digital readout Gt located on digital display 5 indicates total rate of fuel consumption. Yet another digital readout R2 located on the digital display 5 indicates the rpm status of engine 7. Likewise, a digital readout R3 located on the digital display 5 indicates the rpm status of engine 8. Another digital readout 63 displays the percentage of fuel being saved as a result of engine throttle adjustments.

A start trim digital pushbutton 58 and a reset digital pushbutton 59 on digital display 5 start and resets.

Referring now to drawing FIG. 3, there is illustrated a ladder logic diagram used for operating of the system in accordance with the present invention. The following abbreviations are utilized:

T2=Thrust of drive unit 2

T3=Thrust of drive unit 3

Tt=Total thrust required

R2=RPM of drive unit 2

R3=RPM of drive unit 3

Rmax=Maximum allowable RPM

Rmin=Maximum allowable RPM

G2=Fuel being consumed by drive unit 2

G3=Fuel being consumed by drive unit 3

Gt=Total fuel being consumed=G2+G3

E2=Efficiency of drive Unit 2=T2/G2

E3=Efficiency of drive Unit 3=T3/G3

V=Vessel Speed

At the onset of a passage, the vessel 1 operator sets a course and achieves a desired speed and heading. The fuel trim program is then initiated by depressing the start trim pushbutton 58 thus energizing relay 49. Two sets of normally open relay 50 contacts close to enable the digital indicator lights 28, 29, 30 and 31.

If the sum of the thrusts measured at 9 and 10 exceeds the total thrust Tt required for maintaining a predetermined vessel 1 speed and heading than statement block 37 is true and relay 38 is energized and its normally closed contacts open to disable digital indicator lights 29 and 30 thus prompting the operator to decrease either drive unit 2 or drive unit 3 dependent on the status of efficiency statement blocks 45 and 47.

If the sum of the thrusts measured at 9 and 10 is less than the total thrust Tt required for maintaining a predetermined vessel 1 speed and heading then statement block 39 is true and relay 40 is energized and its normally closed contacts open to disable digital indicator lights 28 and 31 thus prompting the operator to increase the RPM of either drive unit 2 or drive unit 3 dependent on the status of efficiency statement blocks 45 and 47.

If the RPM of drive unit 2 measured at 16 exceeds the predetermined limit Rmax by 5% then statement block 41 is true and relay 42 is energized and its normally closed contact opens to disable digital indicator light 29.

If the RPM of drive unit 3 measured at 17 exceeds the predetermined limit Rmax by 5% then statement block 43 is true and relay 44 is energized and its normally closed contact opens to disable digital indicator light 30.

If the efficiency of drive unit 2 as calculated by the software exceeds the efficiency of drive unit 3 then statement block 45 is true and relay 46 is energized and its normally open contact closes to enable digital indicator light 29 thus prompting the vessel 1 operator to increase the RPM of drive unit 2.

If the efficiency of drive unit 2 as calculated by the software is less than the efficiency of drive unit 3 then statement block 47 is true and relay 48 is energized and its normally open contact closes to enable digital indicator light 30 thus prompting the vessel 1 operator to increase the RPM of drive unit 3.

When all digital indicator lights are disabled, maximum fuel efficiency function will has been achieved. The digital indicator lights will remain disabled during vessel 1 passage provided external forces on vessel 1 such as wind, current; sea state etc. remain constant.

Reset pushbutton 59 is depressed by the vessel 1 operator prior to a new course and/or speed setting.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the particular forms herein shown and insofar as indicated by the scope of the appended claims.