Abstract:
A marine propulsion system comprising an engine, hydraulic pump, torque motor and propeller combination. The system is currently adaptable to diesel fuel operated engines. The hydraulic pump is a pressure compensating pump. The hydraulic pump a pressure relief value incorporated to minimize damage to the system due to propeller strikes. Engine and hydraulic pump operating controls/valves are included. Preferably, synthetic grade hydraulic fluid is used. The system is configured for use in any one of an inboard shaft drive configuration, an inboard/outboard motor configuration, an outboard motor configuration and a multi-propeller drive configuration.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/783,611 filed Mar. 16, 2006. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention related to marine propulsion system utilizing hydraulic power to drive the propellers. 
       BACKGROUND OF THE INVENTION 
       [0003]    Even from the early days, propeller drive marine systems had always used the revolutions per minute (rpm) of an engine as a direct relationship to the rpm of the propeller. Increasing the engine rpm would directly increase the rpm of the propeller. This relationship continues even today with the use of transmissions incorporated into the drive train, that is, the rpm of the propeller is still directly proportional to the engine rpm. 
         [0004]    This relationship of the engine producing high rpm to increase the propeller rpm tends to utilize the engine horsepower rather than the engine&#39;s torque aspects. The draw back to this propulsion system is inefficiency in fuel usage. 
         [0005]    The higher an engine&#39;s rpm, which directly causes an increase in fuel consumption, is a problematic issue that causes the need for large fuel storage capacity, which consequently decreases the use full load and further contributes to the fuel consumption inefficiency of this type of propulsion system. 
         [0006]    The need for our inventive marine propulsion system disclosed herein is driven by the rise in fuel cost for both commercial and pleasure boating. These costs continue to rise, out pacing all other economic inflation indices. In addition global warming from fossil fuels need to be dramatically reduced in order to help stabiles the environment, the boating industry accounts for a substantial percentage of these emissions. 
         [0007]    Other environmental issues are also addressed by our marine propulsion system such as noise decimal reduction which directly affects the operator, passengers and wild life. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention is a marine propulsion system that utilized hydraulic power. Typically it would comprise the vessel engine, a self-compensating or pressure compensating hydraulic pump and a torque motor with appropriate controls systems to drive the propellers of the vessel. The system operation is accomplished by utilizing the engine supplying power directly to the self-compensating hydraulic pump that will power and control the drive torque motor, which in turn drives the propeller. The drive torque motor can be configured and adapted to a shaft drive system, an inboard/outboard configuration, or to an outboard configuration, and also single or dual drive operation as needed. In addition, the operational control of the system will be conventional, so there is no special training concerns for the operator. 
         [0009]    The preferred hydraulic fluid selected to be used in the inventive propulsion system is synthetic hydraulic fluid, which is bio-degradable and non-toxic to people, wild life or the environment and is self-extinguishing in the event of a fire. Also in keeping the operation range equal to the previous boat specification dramatically decreases the fuel requirements, which in the event of a mishap again reduces environment impact. 
         [0010]    The advantages of the invention marine propulsion system are many. Fuel consumption is perhaps the most advantageous and the driving force for this invention, but there are other advantages that also translate into economic enhancements. First of which is the reduction of weight of the drive system, which again translates into additional fuel savings. Secondly, the drive system is simplified in that it has less moving parts, which consequently directly reduces maintenance cost and increases reliability. The engine rpm operating range is dramatically lower thereby increasing the operating life expediency of the engine and again lower maintenance cost. Furthermore, since the engine rpm operating range is decreased, this will produce lower noise decimal output. 
         [0011]    There are additional considerations to be made. If the operating range of these boating specifications were unchanged from the original drive system, then a reduction in fuel storage space would prevail and decrease the original drive system, then a reduction in fuel storage space would prevail and decrease the operating weight and increase the use full load which could translate to more cabin space or storage, etc. 
         [0012]    the inventive drive system has yet another advantage in that there is reduced damage to the propeller and drive train from propeller strikes or sudden stoppage, reducing maintenance cost further. Additionally the drive system has the ability to select forward or reverse at full throttle operation. 
         [0013]    Finally, the installation of the invention can be configured to existing drive configurations such as shaft drive system or an inboard/outboard and outboard configuration, single or dual drive operations. 
         [0014]    Again, in summary, the invention is a marine propulsion system comprising: an engine; a hydraulic pump; a torque motor; and a propeller, wherein the engine being in mechanical communication with the hydraulic pump, which is in hydraulic fluid communication with the torque motor, which in turn is in mechanical communication with the propeller. 
         [0015]    The hydraulic pump further comprises means for relieving sudden increases in hydraulic system pressure, thereby reducing possible damage to the marine propulsion system, control means for operating the engine, control means for operating the hydraulic pump, and a hydraulic pump control valve in fluid communication with hydraulic fluid conduit lines communicating with the torque motor. Preferably, the hydraulic fluid is a synthetic grade hydraulic fluid. 
         [0016]    The invention may be configured for use in any one of an inboard shaft drive configuration, an inboard/outboard motor configuration, an outboard motor configuration and a multi-propeller drive configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    In the accompanying drawings, 
           [0018]      FIG. 1  is a conceptual schematic depiction of the invention being used in a shaft drive configuration; 
           [0019]      FIG. 2  is a conceptual schematic depiction of the invention representing its use in an inboard/outboard motor configuration; 
           [0020]      FIG. 3  is a conceptual schematic depiction of the invention representing its use in an outboard motor configuration; and 
           [0021]      FIG. 4  is an example of conceptual schematic depiction of the invention representing its use in a multi-drive configuration, in this case, a dual-drive configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Referring to  FIGS. 1-4 , the invention is a marine propulsion system  10  that utilized hydraulic power. The system comprises an engine  12  in mechanical communication with a pressure compensating hydraulic pump  14 , which is in fluid communication with a torque motor  16 , which in turn is in mechanical communication with a propeller  18 . In a multi-propeller system, pump  14  would be in fluid communication with one or more torque motor/propeller combinations  16 ,  18 , and it is understood that a single or multi-pump control  20  lever system could be incorporated.  FIG. 4  representationally depicts a dual propeller system. 
         [0023]    The engine  12  is contemplated to be a diesel engine, given today&#39;s technology; however, it is contemplated that as new engine technology is developed, engines powered by gas and alternative fuels may become compatible for the hydraulic component necessary to make the invention. 
         [0024]    This system  10  operation is accomplished by utilizing an engine  12  supplying power directly to the power pressure compensating hydraulic pump  14  that will power and control the drive torque motor  16  which in turn drives the propeller  18 . The drive torque motor  16  can be configured to a shaft drive system as depicted conceptually in  FIG. 1 , an inboard/outboard configuration as depicted conceptually in  FIG. 2 , an outboard configuration as depicted conceptually in  FIG. 3 , and also a single or dual drive operation as depicted conceptually in  FIG. 4 . 
         [0025]    In addition the operational control of this inventive system  10  will be conventional, so there will be no training concerns for the operator. 
         [0026]    The engine  12  supplying power to the marine propulsion system  10  will have low rpm high torque specification requirement in order to fully utilize the design advantages of the invention. The engine  12  will have two modes of operation, idle for non-operation running and on-speed condition for operational running using control means, typically an engine control lever  22 . 
         [0027]    This engine  12  will be coupled to a hydraulic pump  14 , by a drive adapter  24 . The adapter  24  will maintain a one to one rpm relationship with the engine  12  and hydraulic pump  14 . 
         [0028]    the preferred hydraulic pump  14  for use in the invention is a pressure compensating vane type pump with operational control valves  26  in fluid communication with the pump  14 . The outlet and inlet hydraulic fluid lines  28 , of the pump control valve  26  will be directed to a torque motor  16 . This torque motor  16  incorporates a splined output shaft  30  that is mated to a propeller  18 . 
         [0029]    The location of the torque motor  16  can utilized with any of the existing drive configurations of the current production boat hulls being produced, such those configuration shown in the drawings,  FIGS. 1-4 . The pump  14  selected also incorporates a pressure relief valve  32 , which in the event of a propeller  18  strike will bypass the system pressure thereby reducing possible damage. 
         [0030]    It is preferable that the hydraulic fluid selected for use in the invention by a synthetic fluid that is bio-degradable and non-toxic to people, wild life or the environment and is self-extinguishing in the event of a fire. Typically, this type of fluid would dissipate heat at a high rate eliminating the need for a reservoir, typically associated with hydraulic fluid systems. 
         [0031]    When the controls  20 ,  26  are selected by the operator for forward or reverse the engine speed will be accelerated to a predetermined constant operational speed that will optimize the hydraulic pump  14  performance, the control lever  20  will also control the pump&#39;s directional output, forward, aft or stationary. In addition, increasing or decreasing control movement in forward or aft conditions will directly increase or decrease pump operational output, thereby directly increasing or decreasing the torque motor speed and direction. 
         [0032]      FIG. 2  also representationally depicts the outboard portion outboard of the hull  36  and the outboard mounting plate  34 .  FIG. 3  also representationally depicts the outboard engine housing  38 . 
         [0033]    There are many advantages to the inventive hydra-marine propulsion system as compared to the marine industry standard systems in place today, first and foremost is dramatically reduced fuel consumption, other advantages are as followed: 
         [0034]    The invention is a simplified drive system, which has “less moving parts,” which increases reliability and reduces maintenance cost. There are reduced exhaust emissions and a noise level reduction. Engine life span is increased by reduced and constant RPM operation. There is reduced damage to propeller and drive train from propeller strikes. Synthetic hydraulic oil, which in non-toxic to the environment “bio-degradable,” also dissipates heat five times faster than conventional oil thereby eliminates the need for a reservoir and is fire resistant. There is no drive train banging or grinding when selecting forward or reverse and there is smooth instant acceleration with the ability to select forward or reverse at full throttle operation. 
         [0035]    As noted above, the system utilizes the unique characteristics of standard components manufactured in both the hydraulic and diesel industries. The diesel engine with high torque and low rpm capabilities, coupled with a variable displacement hydraulic drive system, results in a substantially lower fuel consumption rate, with increases speed and performance. 
       EXAMPLE 
       [0036]    A 220 hp (horsepower) diesel engine at 1500 rpm will develop 650 ft -lbs (foot-pounds) of torque with a fuel burn rate of about 3.4 gallons (12.87 liters) per hour under load. Note: Driven by the engine at this rate, the hydraulic pump reduces (max flow) from 0 to 7,500 psi (pounds/inch 2 ). Note 1 psi equals 0.07103 kilogram.force per square centimeters (kgf/cm 2 ). With the propeller attached directly to a variable displacement torque drive, shaft speeds from 1 rpm to 5,000 rpm can be achieved through the 12 v DC hand operated flow control, mounted at the helm. 
         [0037]    Hull speeds will vary depending on the type, length, width, weight, draft, wetted surface area and prop configuration. 
         [0038]    In direct comparison, a conventional system will burn about 12-20 gallons (45.42-75.71 liters) of fuel per hour at full throttle. This system will burn 3.4 gallons (12.87 liters) per hour or less to achieve the same performance. 
       System Advantages 
       [0039]    In addition to the lower fuel consumption rate, there are other advantages which directly affect the boating industry.
   A. The sound level of the system is drastically reduced compared to a conventional drive, due to the reduced engine rpm (under 40 decibels).   B. The engine can be located strategically in the hull with longer or shorter hose assemblies (critical for center of gravity “CG” installation).   C. The hydraulic oil is biodegrabable and self extinguishing (environmentally approved).   D. Maximum heat dissipation with this type of oil reduces the reservoir to less than 10 gallons (38.85 liters).   E. No smoke when accelerating with the engine at a constant rpm.   F. Propeller rpm range from 1 revolution per minute allows better docking maneuverability and eliminates the need for a trolling motor.   G. No alignment difficulties, or excessive shaft angles resulting from engine placement.   H. Fewer parts such as U-joints, transmissions or gears, results in reduced maintenance costs and higher percentage of efficiency.   
 
         [0048]    The invention can be readily adapted to any conventional hull type including twin out drives or through hull shafts with one or two engines. Each installation is based on size, load, and performance of the vessel to determine various component requirements (engine, pump and torque drive). In development use, the system was found to perform well within the parameters of the equipment and functional capacity of these components. Due to recent advancements in technology, both in the hydraulic components and diesel engines, we have reached a point where this type of propulsion system can effectively reduce the cost of operating a vessel by 60%. 
         [0049]    It should be understood that the preceding is merely a detailed description of one or more embodiments of this invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit and scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.