AU1011983A - Water turbine - Google Patents

Description

"WATER TURBINE"

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a water turbine that may be used to produce rotary drive motion for a water pump, a generator, or other equipment. More particularly, it relates to such a water turbine having improved features of construction which reduce the cost of manufac¬ turing the turbine and increase the usefulness of such turbines under varying conditions of use.

2. Description of the Prior Art

Small scale water turbines that may be placed in streams or similar sources of flowing water to obtain rotary motion for driving pumps, generators and similar equipment are known.^" For example, such a water turbine is disclosed in U. S. Patent 3,904,323, issued September 9 , 1975. While such units have proved useful in practice, the turbine propellers in the unit there described have curved blades in a one piece casting and are therefore expensive to produce. Also, the configuration of the water turbine there disclosed requires that a plurality of turbine pro¬ pellers be provided along a rotatable shaft, with a con¬ siderable distance (e.g., about 1 ft. or 30 cm) between each blade. The result is a unit of considerable length,

OMPI which is both bulky and of considerable expense to provide. The turbine as disclosed in the above patent includes a flow restricter for preventing water flowing through the turbine from submerging more than half of each propeller in the water. As taught in the patent, such construction is necessary to maintain a reasonable efficiency in output from the turbine. Commercially availa.ble units as described in the above patent, but omitting the inlet water flow restricter are also known in the art. However, care must be utilized with such commercial units to prevent more than half of each turbine propeller from being submerged in the water flow if they 'are to operate with a high level of efficiency.

It should be recognized that such water turbines may be operated under a wide variety of conditions. Widely varying water flows and pressure heads, and differing power requirements of units driven by the water turbine mean that it would be advantageous if the turbine could be adjusted to compensate for such variations. For the above and similar reasons, further development of prior art water turbines is necessary to meet different operating conditions encountered in practice. Such. n ability would substan¬ tially increase the usefulness of such water turbines in remote locations and where the ability to provide low cost power on a small scale basis is important. As energy costs continue to climb, the provision of small water turbines able to operate efficiently under different con¬ ditions encountered in streams will assume increasing significance. SUMMARY OF THE INVENTION:

Accordingly, it is an object of this invention to provide a water turbine that is adjustable to meet dif¬ ferent operating conditions.

It is another object of the invention to provide an easily portable water turbine.

It is still another object of the invention to ^• provide a water turbine with a reduced cost of manufacture.

It is yet another object of the invention to provide a water turbine that has a high level of efficiency with closely spaced turbine propellers.

It is yet another object of the invention to provide a water turbine that maintains a high level of operating efficiency without a baffle to control the depth of water flow through the turbine.

It is still another object of the invention to provide a water turbine that is automatically adjustable for different operating conditions to provide a constant rate of rotation.

The attainment of the foregoing and related objects may be achieved through use of the novel water tur¬ bine herein disclosed. A water turbine in accordance .with this invention has a plurality of multiple bladed propellers mounted along a shaft. The shaft is rotatably mounted and axially disposed along a cylindrical housing. A plurality of flow diverters which are preferably planar in configuration are mounted on the housing and extend between adjacent ones of the propellers. The flow diverters serve to direct water flow from one of the propellers substantially normal to a next adjacent propeller in the direction of water flow through the turbine.

In another aspect of the invention, the blades of the propellers are mounted on a centrally disposed hub in a manner that allows their pitch with respect to the water flow to be adjusted. The blades are further prefer¬ ably of a planar configuration, so that they can be fabri¬ cated from conventional sheet metal stock. In one form of this aspect of the invention, the pitch of the blades is automatically controlled to maintain a constant drive rotation rate.

When constructed of conventional sheet metal stock in accordance with this invention, a water turbine weighing about 80 lbs. (36 kg) can be provided. Such a uni will provide a power output at least equal to that obtainabl with presently available prior art turbines as discussed aborv, which weigh about 300 lbs. (135 kg) and are signifi¬ cantly more expensive to fabricate than the turbine of this invention. Further, the pitch angle of the turbine pro¬ pellers may be varied in the turbine of this invention, while. the prior art water turbines have a fixed configura¬ tion.

The attainment of the foregoing and related . objects, advantages and features of the invention should be more readily apparent to those skilled in the art after review of the following more detailed description of the invention, taken together with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS:

Figure 1 is a top, sectional view of a water turbine in accordance with the invention;

Figure 2 is an end view of the water turbine shown in Figure 1;

Figure 3 is a plan view of a turbine propeller in accordance with the invention, which may be employed in the water turbine of Figures 1-2;

Figure 4 is a perspective view of a portion of the turbine propeller shown in Figure 3;

Figure 5 is an exploded perspective view of the propeller portion shown in Figure 4, showing further details of construction;

Figure 6 is a side view of a portion of another water turbine in accordance with the invention;

Figure 7 is a partial side view and a block diagram of another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVKNTTOM-

Turning now to the drawings, more particularly to Figures 1 and 2, there is shown a water turbine 10 in accordance with the invention. The turbine has a cylindrical housing 12. A shaft 14 is axially disposed along the housing 12 and is rotatably mounted to pass through supports 16, preferably by means of self-aligning pillow blocks 18 mounted on the supports 16. A plurality of propellers 20 are fixedly mounted along the shaft 14. Between adjacent ones of the propellers 20, stators or flow redirectors 22 are mounted on the housing 12 and extend between the propellers 20, as shown. A flexible coupling or universal joint 24 joins the shaft 14 to drive shaft 26 of a 12 volt alternator 28. The alternator 28 may be re¬ placed by a conventional generator, a water pump, or a refrigeration compressor. Housing 12 is composed of a lower half 30 and an upper half 32, each of semicircular cross-section, which may be joined together along their lengths by means of a flange (not shown) . Handles 36 are provided on each half 30 and 32 to facilitate carrying the water turbine 10, and also to facilitate separation of the housing halves 30 and 32 for adjustment and maintenance of the turbine. As is best shown in Figure 2, the upper half 32 of housing 12 does not have stators or flow redirectors because water flow usually takes place in only the lower half 30 of the housing in use of the turbine. Flared entrance 34 helps direct water flow into the housing 12 whe the turbine is placed in a stream or similar body of flowin water.

In operation, water flow enters inlet end 40 of the turbine 10 and impinges against blades 42 of the first propeller 20, as is indicated by arrows 44 (Figure 1). The force of water impinging against blades 42 causes the propeller 20 to rotate, and gives a diagonal direction of flow to the water, as indicated by arrows 46. ^' In order for the water flow to provide the same action against the blades 42 of the next propeller 20 in the direction of flow it is necessary that the water flow 20 once again assume a horizontal direction, as shown by arrows 48. The stators or flow redirectors 22 between adjacent propellers 20 accomplish this flow redirection with a minimum of spacing between the adjacent propellers 20. For example, the stators 22 may have a width of 2 inches (5 cm) plus sufficient clearance with respect to the propellers 20 to allow for rotation of the propellers 20. In contrast, relying on the walls of a turbine housing to accomplish flow redirection requires a spacing of about 1 ft. (30 cm) between adjacent propellers for optimum efficiency.

Figures 3, 4 and 5 show details of construction o the propellers 20 for the turbine of Figures 1 and 2. Blades 42 are preferably fabricated of flat sheet metal stock and have a channel-shaped opening 60 (Figure 5) which faces a centrally disposed hub 61, to which the blades 42 are mounted. The fan shown has four blades, so that hub 61 will have a polygonal shape, with the number of sides 62 corresponding to the number of blades 42. Blades 42 should overlap as shown in Figures 2 and 3 to provide a propeller 20 of maximum power generation efficiency. Hub 61 is in turn fixedly mounted on shaft 14 (Figure 1) .

As shown in Figures 4 and 5, each blade 42 has a sleeve 66 welded or otherwise fixedly mounted to the blade 42 within channel 60. A socket head cap screw 68 passes through the sleeve 66 and washer 70 and is threaded into mating aperture 72 in hub 61. A wrench 74 having a tip 76 for insertion into holes 78 in head 80 of screw 68 allows the mounting of blade 42 to hub 61 to be loosened for adjustment of" the pitch, as indicated by arrows 82 in Figure 4. The blade 42 is held at a desired pitch until screw 68 is tightened to restrain the blade 42 against further motion with respect to hub 61. In use, the blade 42 typically has a pitch of between about 10° and 50°_ depending on flow rate and pressure head of water moving through the housing 12, with th<a smaller pitch angles being used with smaller water flow rates in order to maintain a given shaft rotation rate.

Figure 6 is an embodiment of the invention in which constant revolutions per minute (RPM) can be obtained through the use of a flyweight governor 100 mounted on a shaft 102 to control the RPM of the shaft 102. Flyweight governor 100 includes a cam 104 biasing sleeve 106, slideabJ mounted on shaft 102^upward as weight 108 moves away from shaft 102. Sleeve 106 is fixedly connected to pitch contro rod 110, which is also pivotally connected to each of the propeller blades 112. In this embodiment, the blades 112 are pivotally mounted in hubs_.114 so that the pitch angle of the blades 112 may be varied in response to action of the flyweight governor 100. Spring 116 biases sleeve 106 against cam 104. Suitable bearings, such as indicated at 118, are provided for rotatable support of the shaft 102. A power takeoff 120 connects shaft 102 to a pump or other unit to be powered by the water turbine.

Figure 7 shows another embodiment of the inventio in which the automatic control function of the Figure 6 embodiment is accomplished electronically. An RPM sensor

202, for example, a magnetic rotor and stator assembly of the general type employed in electronic ignition applica¬ tions, senses the rotation of shaft 204 as indicated at 206. The resulting RPM information is supplied to micro¬ processor 208 as indicated at' 210. Microprocessor 208 selects operating parameters necessary to achieve a pre¬ determined RPM and supplies suitable drive commands on line 212 to interface and drive circuits 214 to drive solenoid or other suitable drive means 216 mechanically coupled to vary the pitch of turbine propeller 218 for achieving the desired RPM. An input/output device 222 can allow user selection of pitch, RPM or other operating conditions or output characteristics. Feedback through the RPM sensor allows continuous monitoring and adjustment of the pitch of turbine propeller blades 218 in a water^' turbine incorporating this embodiment to maintain the desired RPM or other operating characteristic. Suitable sensors for other operating parameters, such as water flow rate, may also be connected to provide inputs to micro¬ processor 208 for use in controlling the automatic water turbine O'f Figure 7.

Water turbines as shown in Figures 1 through 7 may be fabricated with housings 12 of different diameters, for example 12 inches, 16 inches or 20 inches (30, 41, or 51 cm) from high strength, light weight and corrosion/rust resistant materials. The shaft 14, bearings 18 and hubs 61 are all interchangeable in these different sizes;_., only the blades 42 need be changed. Bronze, stainless steel..and aluminum are used wherever possible. The number of blades 42 on the propellers 20 can be varied from, for example, three to eight .

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OMP In a specific example, a water turbine in accord¬ ance with Figures 1 through 5 embodiment and having a housing diameter of 16 inches - (41 cm) , a 48 inch (122 cm) length casing and a 45° blade pitch and a total of four propellers will drive a 3/4 horsepower pump at 100 RPM when placed in a stream at an angle to give a drop of 11 inches (28 cm) in 48 inches (122 cm) and allow water to flow with the lower half 30 of housing 12 three-quarters full to pump water a height of 40 to 50 feet (12 m to 15 m) at a rate of 56.25 gallons (214 L) per hour. Thi- water turbine will also drive a 12 volt alternator to give a constant output of ^"55 amperes under the- same water flow conditions .

In further performance tests, this water turbine and pump gave the results shown in the following table when used to deliver water to a height of 50 feet (15 m) and a depth of water flow through the turbine 2 inches (5 cm) below the center of its housing 12.

Angle of Turbine Delivery, Gal¬ in Stream RPM Pressure lons per hour

10" drop in 48" 150 35 psig 68.82

6" drop in 48" 90 35 psig 41,28

4" drop in 48" 60 35 psig 27.54

Using the first angle of the turbine in the strea shown in the table, the turbine was able to produce a water pressure of 80 - 90 psig at 25 RPM, and the pump delivered water at a rate of 11.46 gallons per hour to a height of 100 feet (30 ) .

If desired, several of the water turbines 10 may be interconnected end-to-end in order to increase the available power output. -li¬

lt should further be apparent to those skilled in the art that various changes in form and details of the invention as shown and described may be made. For example, certain of the principles of construction employed in the water turbine as shown may be incorporated in wind turbine as well. It is intended that such changes be included within the spirit and scope of the claims appended hereto.

Claims (11)

WHAT IS CLAIMED IS:

1. A water turbine, which comprises a plurality of multiple bladed propellers mounted along a shaft, said shaft being axially disposed along said housing, and a plurality of flow diverters mounted on said housing and extending between adjacent ones of said propellers, said flow diverters serving to direct water flow from one of said propellers substantially normal to a next adjacent propeller in the direction of water flow through the turbine.

2. The water turbine of Claim 1 in which said housing has a substantially unrestricted inlet end com¬ municating with a first one of said propellers in the direction of water flow through said housing.

3. The water turbine of Claim 1 in which the blades of said propellers are substantially planar.

4. The water turbine of Claim 1 in which the blades of said propellers have an adjustable pitch.

5. The water turbine of Claim 4 in which the blades of said propellers each have a sleeve through which a threaded member passes to fasten each blade to one side of a polygonal hub, said hub being fixedly mounted to said shaft. i 6. The water turbine of Claim 4 additionally comprising a shaft rotation rate sensing means coupled to sense shaft rotation and means responsive to said sensing means for varying the pitch of the blades to maintain a

5 predetermined shaft rotation rate.

1 7. The water turbine of Claim 6 in which said shaft rotation sensing means comprises a flyweight governo mounted on said shaft and said pitch varying means com¬ prises a linkage connecting the flyweight governor to the

5 turbine blades.

1 8. In a fluid driven turbine having propeller blades with a variable pitch, the improvement comprising a propeller rotation rate sensing means and a means respon¬ sive to the propeller rotation rate sensing means connecte

^•5 to change the variable pitch of the propeller blades in order to maintain a predetermined propeller rotation rate in response to changes in turbine operating conditions.

9. The fluid driven turbine of Claim 8 in which said rotation sensing means comprises a flyweight governor.

10. A propeller for a fluid driven turbine which comprises a centrally disposed hub having an axial passage¬ way therethrough for fixedly mounting said hub on a shaft, said hυ.b having a plurality of outwardly facing threaded apertures, and a plurality of blades, each blade having a sleeve through which a threaded fastener passes to attach one of the blades to said hub at each threaded aperture, said fastener when loosened allowing the blade to be pivoted for varying its pitch on said hub and when tightened serving to fix said blade at a particular pitch on said hub.

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11. The propeller of Claim 10 in which said sleeve is fixedly mounted in a channel at a base end of its associated blade, the channel extending along said blade to a sufficiently greater extent than said sleeve to receive a head of said fastener.