Abstract:
The present invention relates to an apparatus for providing electrical energy from a flowing stream of water by capturing the flowing stream and transferring the captured energy to a rope which passes through a plurality of rotors connected to an electricity generator.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    There is a growing demand for alternative forms of energy production which utilize renewable sources of energy to produce useable electrical or other energy. Solar panels and wind turbines are in growing demand, but do not provide base power because the energy supply (sun or wind) is not constantly available. Therefore, in order to utilize energy produced from solar panels or wind turbines, the energy must be stored in some form of battery. 
         [0002]    One form of energy which is renewable and in constant supply is energy from flowing water. Flowing water provides a constant energy source with high torque and generally low speed. There have been other attempts to produce energy from this source, such as my previous U.S. Pat. No. 3,887,817. As systems such as the one described in my &#39;817 patent are scaled for greater production, however, previously unforeseen issues arise. 
         [0003]    One such issue is the high stress placed on the rope or chain. In a single rotor system, such as described in my &#39;817 patent, the rope experiences a high tension differential between entering and leaving the rotor. This results in premature wear of the rope, leading to system failure and down time. 
         [0004]    Therefore, it is a primary purpose of this invention to provide an apparatus which is able to extract useable amounts of energy from a flowing stream of water and convert it into useable energy, such as electricity. 
         [0005]    It is a further purpose of this invention to provide an apparatus which is able to scale from experimental to useful scales without significant modification. 
         [0006]    It is a still further purpose of this invention to provide an apparatus designed to gradually reduce the tension in the rope so as to eliminate premature wear. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The invention generally relates to an apparatus for producing electricity from a flowing stream of water. The apparatus is generally mounted on a boat, pontoon, or other floating platform which is secured relative to the shore such that the water flow passes by the floating platform. A rope, chain, or other flexible loop member is lowered into the water stream and a plurality of cups, parachutes, or other momentum exchange device adapted to provide linear force to the continuous loop member from the flowing stream of water. The continuous loop member is threaded through a plurality of rotors, the rotors transferring the linear force to rotational force for use by an electricity generator. 
         [0008]    A plurality of rotors is required to provide a gradual stepping off of the tension on the continuous loop member. This provides that the tension is distributed over a longer length of the continuous loop member, reducing the strain and eliminating the potential for premature wear or failure. The tension differential between any two rotors varies based on their position relative to the point where the continuous loop member picks up force. Each rotor will therefore rotate at different rates, the rotational energy will then be captured by the generator and transformed into electrical potential. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a top view of the preferred embodiment of the invention. 
           [0010]      FIG. 2  shows an enlarged top view of the preferred embodiment. 
           [0011]      FIG. 3  shows a side view of one rotor taken along line  3 - 3 . 
           [0012]      FIG. 4  shows an enlarged view of a momentum exchange device. 
           [0013]      FIG. 5  shows a schematic of the power generator. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    The invention will now be described with reference to the numerals in the attached figures. 
         [0015]    As shown in  FIG. 1 , the invention generally comprises a continuous loop rope  20  having a number of parachutes  26  positioned at points along the rope  20 . The rope  20  is positioned into a water source  32  having a current  34 . The parachutes  26  are designed to automatically open and close in order to capture the force of the current  34  and provide linear force to the rope  20 . The rope  20  passes through a number of rotors  18  positioned on a frame  12 , the rotors  18  transferring the linear motion of the rope  20  to rotary motion. The rotors  18  are connected to a generator  50  to produce electricity. The frame  12  is preferably mounted on a floating device  52 , such as a pontoon or raft. The pontoon or raft  52  is anchored relative the current  34 . 
         [0016]    As shown in  FIG. 2 , the frame  12  has a plurality of rotors  18  arranged thereon. Each rotor  18  has a tapered cleavage  54  for receiving a continuous loop rope  20 . The rope  20  passes through each rotor, and as a force is applied to the rope  20 , the rotors  18  are caused to turn. Preferably, the rotors are arranged so that the rope  20  engages each rotor  18  over half its circumference, thereby maximizing the amount of power extracted from the moving rope  20 . The plurality of rotors  18  are engaged with an electricity generator  50 . 
         [0017]    As shown in  FIG. 3 , the rotors  18  are arranged in a pair of rows. The rotors are staggered and positioned such that the rope  20  engages each rotor  18  over approximately half of its circumference. The frame  12  also features a pair of guide wheels  16  positioned adjacent the trailing edge of the frame  12 . These guide wheels ensure that the rope  20  does not drift in the current  34 . Guide wheel  8  is located near the downstream portion of frame  12  to control the lateral movement and to guide the rope  20  out of the water and into the plurality of rotors  18 . 
         [0018]    A pair of elongated horizontal rollers are located at the extreme downstream portion of frame  12  adjacent guide wheels  16  and  8 . These rollers operate on the top side and in contact with the rope  20  to control the vertical angle of entry and exit of rope  20  into guide wheels  16  and  8 . The horizontal rollers feed rope  20  directly into the cleavage of guide wheels  16  and  8  to ensure that the rope  20  does not become disengaged during operation in large ocean waves. Thus, with guide wheels  16  and  8  and the two horizontal rollers, the lateral and vertical angles of attack of the rope  20  into the rotors  18  are controlled. 
         [0019]    Shield  6  serves as a cover or shroud to prevent any portion of the rope  20  to rise above the cleavage  54  in rotors  18  or the cleavage in any guide wheel  8 ,  14 . The cleavage  54  is the only portion of rotors  18  or any guide wheel  8 ,  14  to extend through and below the shield  6  to prevent the entanglement of the rope  20  or parachutes  26  with any moving parts. Shield  6  extends throughout and immediately above any area where the rope  20  operates, the only thing below the cleavage  54  is water. 
         [0020]    A large pulley  14  is positioned at the leading edge of the frame  12  for guiding the rope  20  into the plurality of rotors  18  and to space the rope  20  away from the rotors, reverse the direction of the rope  20  from an upstream direction into a downstream direction that allows the water current  34  to begin filling the open end  28  of the parachute  26  for another power cycle of the continuous loop rope  20 . The pulley  14  provides for aligning the rope  20  vertically and ensuring it enters the rotors  18  at a proper angle. 
         [0021]      FIG. 4  shows the parachute  26 , or momentum exchange device, mounted to the rope  20 . The rope  20  features a number of attachment points  22  positioned about its length. At each of these attachment points is a parachute  26 . Each parachute  26  has an open end  28  and a closed end  30 , and a number of lines  24  extending from the parachute towards the open end  28 . The lines  24  attach to the rope  20 , and transfer force generated by the parachute  26  to the rope  20 . The lines  24  also ensure that the parachute  26  remains open when the open end  28  faces the current and closed when the closed end  30  faces the current. 
         [0022]    As can be appreciated by those skilled in the art, as the rope  20  is pulled taut by the current  34  working on the parachutes  26 , the rope  20  tends to stretch. The rope  20  is stretched by the force differential acting along the length. The rope  20  experiences a maximum tension T max  at the guide wheels  16  as the rope enters the water  32 , and a minimum tension T 0  as the rope leaves the water  32  near the pulley  8 . As viewed in  FIG. 2 , the rope  20  travels in a counterclockwise direction during operation, although the device  10  may be configured to operate in the opposing direction. Each rotor  18  reduces the amount of tension in the rope  20  as energy is extracted. For example, as the rope  20  passes rotor  18 A, the tension drops from T max  to T A . The tension differential across the rotor  18 A can be expressed as T A −T max , the “loss” of tension is caused by energy being transferred to the rotor  18 A. As the rope  20  passes the other rotors  18 B-J, the tension drops steadily to T 0 . It is further well known in the art that the rope  20  will experience a spring-like deformation, the deformation measured according to the force acting on any section of the rope  20 . The difference in tension across any of rotors  18 A-K will vary, resulting in variable deformation of the rope as it traverses rotors  18 A-K. As a consequence, each rotor  18 A-K will tend to rotate at a different rotational velocity according. 
         [0023]      FIG. 5  shows a preferred example of a generator intended to capture the energy from each of the rotors  18 . A hydraulic piston pump  42  is attached to each of the rotors  18 . Each hydraulic piston pump  42  provides a variable flow rate at a constant pressure, depending on the rotational velocity of the assigned rotor  18 . The hydraulic piston pumps  42  feed pressurized hydraulic fluid into a common pressurized reservoir tank  44  through a series of interconnecting tubes. This pressurized tank  44  is operably connected to a hydraulically driven motor  46  adapted to utilize pressurized hydraulic fluid to drive a shaft  48  on a generator  50 . The generator  50  produces electricity according to means commonly known in the art. After driving the motor  46 , unpressurized hydraulic fluid is returned to a reservoir  45 . 
         [0024]    The hydraulic system as described provides for a means of normalizing the energy output from a plurality of rotors  18  rotating at different speeds. Other means for producing electricity from the plurality of rotors may be utilized. Some examples include: a plurality of hydraulic pumps operating in series with a constant flow rate; mechanical gearing; independent generators on each rotor; or any other method commonly known in the art. 
         [0025]    The system as shown includes ten rotors  18  arranged such that the rope  20  contacts approximately half of the circumference of each rotor  18 . The number of rotors is not fixed, and may be varied according to need. The principle consideration in choosing the number of rotors is to ensure that the rope does not slip as it passes through the rotors. Rope slippage leads to wear and results in premature failure of the system. Because the rope  20  is an essential structural element, replacing the rope  20  requires power generation to be halted. 
         [0026]    Ideally, the plurality of rotors  18  are of a uniform diameter. However, rotors  18  may vary in size in order to eliminate the difference in rotational velocity between any two rotors  18 . Ideally, no rotor  18  will have a diameter of less than eight times the diameter of the rope  20 . The ratio of 8:1 between rotor diameter and rope diameter is one which is commonly used in the art. This ratio reduces energy losses due to bending the rope about the rotor and prevents slippage of the rope. 
         [0027]    The rotors additionally feature a cleavage  54  for receiving the rope  20 . This cleavage is a tapered opening which ensures that the rope  20  does not slip from the rotor  18 . The tapered cleavage  54  also allows the parachute  26  and lines  24  to pass through the rotor  18  without tearing, creasing, or becoming entangled. Additionally, because the rotors  18  are coplanar with one another and the rope  20  passes through each rotor  18  only once, the parachutes  26  and lines  24  may hang below the rotors  18  and avoid entangling with other parachutes  26  or lines  24 . Other rollers or guides may also be present, the guides lifting, directing, or raising the rope  20  out of the water source  32 . This may be necessary if the frame  12  is elevated from the water source  32 . 
         [0028]    The above description is intended to be exemplary in nature and not limit the invention. Any limitations appear in the allowed claims.