Patent Application
20130009403
NONE
No Federal research or development funds were used in the development of this concept/product.
N/A
N/A
The current generation of wind powered electrical generators is completely dependent upon a sufficient velocity of wind driving their massive propellers, thereby rotating the main throughput shaft which is connected to an electrical generator, spinning the generator which in turn produces electricity for consumer use. The uncertainty of achieving consistent wind velocity and direction has been the historical and primary limiting factor inhibiting large-scale adaption of wind power to augment the national electrical grid and provide a reliable and renewable energy source.
One proposed solution to provide a more consistent wind power supply is to incorporate an efficient natural gas powered engine, driving a hydraulic power unit mounted behind the power generation assembly (on the aft or non-wind end of the power cab) as an alternate locomotive source to turn the electrical generator. The entire auxiliary propulsion system would consist of: 1) a natural gas engine; 2) a high pressure hydraulic pump driven by the natural gas powered engine; 3) a pressure accumulation (storage) tank with associated check and release valves calibrated to the pressure range required to power the propulsion unit; 4) a particulate filter to remove foreign matter from the fluid as it flows through the closed-loop hydraulic system to the reservoir for use by the hydraulic pump; 5) a control panel linked to the sensors mounted on the main generator shaft, and; 6) a hydraulic propulsion system connected to the hydraulic pump via high-pressure lines (hydraulic fluid supply and return). Items 1 through 4 would be mounted at the base of the wind turbine assembly. Item 5 would be mounted inside the base unit. Item 6 (the natural gas engine driven hydraulic pump/hydraulic propulsion system) is mounted inside the power generation cab on top of the elevation mast.
The natural gas engine drives the hydraulic pump which propels hydraulic fluid through a high-pressure connecting line. The hydraulic fluid goes directly to the hydraulic drive motor on the generator. The hydraulic accumulator (which is located in the ground-level building) has a membrane or piston separating the air and oil side, and acts as a pressure pre-load system, and overflow outlet for fluid and back-up supply source. A variable-displacement hydraulic motor mounted inside the power cab (atop the mast) employs a swashplate control and return valves to increase inherent system control and in some applications, may obviate the need for a separate viscous coupling. Another advantage of using swashplate control and return valves is that these control mechanisms would allow the mainshaft to “freewheel” in the depressurized (0 swashplate angle) mode, reducing hydraulic fluid cooling requirements and overall drag on the system when under wind power. Similar control schemes are used in hydraulic systems and hydraulic-driven electrical generators (the constant-speed generators) employed on many aircraft engines.
A water to oil heat exchanger assembly will be integrated into the hydraulic fluid return line to maintain hydraulic fluid temperatures within specified limits. The heat exchanger will be mounted alongside the radiator, which cools the natural gas engine. A one-way check valve is calibrated to the highest specific pressure needed by the propulsion unit will act as a safety override mechanism that shuts off hydraulic fluid flow from the pump. If maximum pressure thresholds are exceeded, the check valve and incorporated pressure sensor simultaneously sends a cut-off signal to the natural gas engine to prevent damage to the accumulator tank and hydraulic lines from over-pressurization. The check valve will be incorporated on the high-pressure supply line.
The combination of the following components: a constant-pressure, variable-displacement hydraulic pump on the gas engine; constant-speed, variable-displacement hydraulic drive motor; individual controllers on each, would take care of all but the most excessive load/speed transients. The clutch/controller on the planetary gear set will act as a secondary mechanism to compensate for engagement load/speed transients above 150% of design load capacity (when the hydraulic motor engages/disengages). Sudden, high-pressure shocks to the various connection joints and propulsion system could cause instantaneous component failure (metal fatigue or shearing) and certainly would reduce the service life of critical components. To ensure that hydraulic fluid used in the closed-loop system remains free of contaminants, an inline filter will be mounted on the return (low-pressure) line as part of the base unit assembly—for ease of maintenance.
The hydraulic propulsion system will consist of a ring and pinion gear assembly, planetary gearbox to increase torque, viscous coupling and harmonic damping flywheel to absorb start/stop engine shock and sensors to monitor shaft speed. The ring gear is impelled by the rotation of the pinion assembly, which translates hydraulic pressure into (right angle) rotational force. The pinion translates right angle motion into torque which spins the ring gear which, in turn, spins the planetary gear assembly. The ratios for the planetary gear set may be varied as required to provide sufficient torque to spin the main generator shaft at specified RPM to meet specified output demand (rated power or peak usage demand). The entire hydraulic propulsion system, including the natural gas engine, is controlled by a series of speed sensors and auto start/stop actuators synchronized, programmed and controlled by the Master Control Panel to work in unison.
The hydraulic propulsion system would automatically send power via a viscous coupling and planetary gear set that engage and turn the electrical generator shaft when wind velocity isn't sufficient to ensure that main shaft revolutions per minute (RPM) remain within generator manufacturer's recommended speed range (minimum speed necessary to generate rated electrical output). The most likely condition causing the auxiliary propulsion system to engage would be insufficient wind velocity (calm days) or gusting velocities that exceed rated rotational speed of the propeller assembly (unpredictable weather/storm conditions), which would fail to turn the main generator shaft at the required RPM to assure specified/rated electrical output. A propeller feathering mechanism could also be incorporated to prevent damage to the large propeller assembly during extremely high winds (storm conditions).
The auxiliary propulsion system would be controlled by employing the latest technology available (sensors, controllers and actuators) that have accrued hundreds of thousands of hours of all-weather use in automotive and aircraft industry applications. Symmetrical sets of sensors, controllers and actuators would be mounted within a control box co-located with the natural gas engine and the hydraulic propulsion unit at the power generator base. The other set of sensors will be mounted on the hydraulic propulsion unit and generator main shaft in the power generation cab atop the mast assembly. All sensors will be capable of calibration to specific generator/applications, as needed and form an integral components comprising the redundant system for shaft speed monitoring and control. The matched (paired) shaft-mounted components sense decreases in speed and provide commands to the natural gas engine/high-pressure hydraulic pump to engage, begin spinning the pinion gear and thusly rotate the ring gear, which is connected to the planetary gear assembly, which in-turn, turns the main shaft axially in absence of wind.
This apparatus ensures instantaneous “on demand” power augmentation to maintain generator shaft RPM in the optimal electricity generating range (peak demand satisfaction or rated output) specified by the generator manufacturer. The sensors and actuators used are extremely rugged, small and have the added benefit of drawing very low voltage when in operation (12v DC).
If the generator shaft RPM drops below the lowest acceptable RPM for demand/rated power generation (250 RPM, for example), a series of redundant electro-magnetic induction (shaft) speed sensors mounted on the generator main shaft (FIG. #2, page 31) would immediately sense a reduction in shaft speed to below the calibrated rotational speed range and transmit an electrical signal to the main hydraulic propulsion system control unit, thereby triggering the natural gas powered aux engine to start-up, come on line and spin the hydraulic pump unit which would then provide a pre-specified volume of high-pressure hydraulic fluid via a delivery line to the hydraulic power unit mounted on center-line axis behind the electrical power generator.
The hydraulic pressure supplied to the power unit via the hydraulic pump would be translated into rotational force via a pinion and ring gear set or via a vaned turbine unit mounted on the generator mainshaft that is turned directly by hydraulic pressure from the hydraulic pump line. The vaned turbine unit would be a more compact and economical approach for low to medium power generation (10 kW to 100 kW range), while the ring and pinion application would be more suitable to megawatt range power generation requirements, because the gearset can be stepped as needed to match torque requirements to spin the electrical generator at the specified revolutions per minute (RPM) to produce rated electrical output.
The pinion gear would engage and turn the axially mounted ring gear which provides rotational force (torque) to the planetary gear system, viscous coupling box and damping flywheel. The aux engine and generator mainshaft will be fitted with electromagnetic (induction) rotational speed sensors and auto-start/stop technology (FIG. #2, page 31), that is very similar to the sensors and controller mechanisms currently employed in hybrid electric-gas automobiles to instantly start-up, engage and then cut-off when not needed, as well as activate and deactivate natural gas engine cylinders for optimum economy of operation during periods of light power demand by the electric generator.
This patent submission represents a proposed solution to this national problem.
318 ELECTRICITY: MOTIVE POWER SYSTEMS
DISCLOSED UNDER 37 CFR 1.97 AND CFR1.98
ART UNIT: 2834
Incorporate (mount) a natural gas powered engine and hydraulic propulsion pump (built from aluminum and cast iron components) equipped with auto start/stop switching and monitored/controlled by primary and secondary control panels mounted at the base of a wind-power generation unit and the power generation cab, respectively. The base unit and primary control panel would be housed in an all-weather utility building, while the secondary control panel would be integrated/installed inside the power generation cab—located atop the generator support mast. Sensors for monitoring main shaft revolutions per minute (RPM) would be adapted from those that have been widely utilized within the automobile industry. The hydraulic power unit would be connected via one of two secondary propulsion mechanisms: 1) a two-stage drive system to the main turbine shaft of the wind powered electrical generator. The two-stage drive system consists of a ring and pinion gearset and a torque multiplying planetary gearbox; 2) via a vaned turbine unit mounted on the generator mainshaft that is turned directly by hydraulic pressure from the hydraulic pump line. The vaned turbine unit would be a more compact and economical approach for low to medium power generation (10 kW to 100 kW range), while the ring and pinion application would be more suitable to megawatt range power generation requirements, because the gearset can be stepped as needed to match torque requirements to spin the electrical generator at the specified revolutions per minute (RPM) to produce rated electrical output.
The auxiliary engine will burn natural gas (NG) supplied by pipeline or compressed natural gas (CNG) via a high pressure storage tank scaled to monthly fuel burn rates as the secondary fuel for wind powered electrical generators (wind being the primary locomotive force), but other fuel sources (propane, diesel, gasoline, kerosene, etc.) would work just as well, though overall cost per hour of generator operation would increase as would pollutant emissions, depending upon fuel choice and availability.
The output range (horsepower) for the engine (FIG. #1, page 30), can be specifically calibrated to the output requirement of the electrical generator and need to maintain desired/specified shaft revolutions per minute (RPM) to obtain optimal electric power output from the generator. The CNG engine will be equipped with all necessary environmental and system related sensors, monitors and switches configured for this application (FIG. #2, page 31), and installed on the auxiliary unit to detect insufficient wind (based upon main shaft—RPM) to turn the main shaft and generate electricity, providing sustaining power to maintain minimum RPM necessary to generate electricity at the rated output level specified by the generator manufacturer.
The engine is connected to a variable-displacement hydraulic pump where applicable/desirable via a direct, viscous coupling designed to absorb engine start-up/shut-down forces (FIG. #2, page 31). This engineering approach allows the engine to run at a single speed (or an array of pre-specified speeds, depending on load) so it could be tuned to the most optimum speed range. Two hydraulic fluid lines (supply and return) connect to the hydraulic propulsion unit, which spins the generator mainshaft through a ring and pinion assembly connected to a planetary gear system which multiplies engine torque, allowing a smaller more efficient engine to provide locomotive power (the design is very similar to those used on state-of-the-art, full-time all wheel drive and hybrid vehicles).
This approach allows power to be efficiently applied to the main generator shaft as needed and also to freewheel when not in use, eliminating drag or resistance on the main shaft when the hydraulic power/propulsion system (auxiliary engine and hydraulic pump assembly) isn't engaged. Matching the variable-displacement pump operating at the base unit is a similar (variable-displacement) hydraulic motor (propulsion unit) mounted inside the power cab (up top) will have enough inherent control via the swashplate control and return valves to obviate a separate viscous coupling. The swashplate valves would also “freewheel” in the depressurized (0 swashplate angle) mode, reducing cooling requirements. This approach is modeled after the scheme used in the constant-speed generators on aircraft engines. The design weight for the aux/dual power unit is approximately 1000 pounds, though weight can vary depending upon rated horsepower specified/required for individual generator applications. More than 80% of the unit's weight will be in the base unit (engine and hydraulic pump). The auxiliary engine will be located at the base of the main power generation cab of the wind powered electrical generator and supply locomotive force to the main generator shaft via a hydraulic pressure to a viscous planetary (reduction gear) system (FIG. #2, page 31), by way of a ring and pinion gearset commonly used in automotive applications. One other method of supplying torque to turn the mainshaft will be through a scaled hydraulic turbine, connected directly to the mainshaft. The planetary gearing system and a viscous coupling system, very much like the power distribution system on a full-time all-wheel drive set-up employed on some sports utility vehicles, allows the auxiliary engine to engage and maintain generator shaft speed when needed and disengage when wind velocity is sufficient to turn the generator shaft. This approach will save fuel and engine wear when the auxiliary power supply isn't needed to turn the main shaft and generate a constant supply of electricity. Inclusion of the planetary gear system is important to the overall design, because the planetary gear assembly multiplies the torque generated by the hydraulic power unit (power head) by a factor of six to ten (6× to 25×), permitting a much smaller aux power assembly to be used in very broad applications, lowering initial and sustained operating costs.
(FIG. #1, page 30), depicts a cross section of the entire device, showing the propeller on the front of the wind turbine and the secondary hydraulic propulsion unit mounted on the rear of the generator.
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Design will incorporate an efficient natural gas powered engine, driving a hydraulic power unit mounted behind the power generation assembly (on the aft or non-wind end of the power cab) as an alternate locomotive source to turn the wind-powered electrical generator. The entire auxiliary propulsion system would consist of: 1) a natural gas engine; 2) a high pressure hydraulic pump driven by the natural gas powered engine; 3) a pressure accumulation (storage) tank with associated check and release valves calibrated to the pressure range required to power the propulsion unit; 4) a particulate filter to remove foreign matter from the fluid as it flows through the closed-loop hydraulic system to the reservoir for use by the hydraulic pump; 5) a control panel linked to the sensors mounted on the main generator shaft, and; 6) a hydraulic propulsion system connected to the hydraulic pump via high-pressure lines (hydraulic fluid supply and return). Items 1 through 4 would be mounted at the base of the wind turbine assembly. Item 5 would be mounted inside the base unit. Item 6 (the natural gas engine driven hydraulic pump/hydraulic propulsion system) is mounted inside the power generation cab on top of the elevation mast.
The natural gas engine drives the hydraulic pump which propels hydraulic fluid through a high-pressure connecting line. The hydraulic fluid goes directly to the hydraulic drive motor on the generator. The hydraulic accumulator (which is located in the ground-level building) has a membrane or piston separating the air and oil side, and acts as a pressure pre-load system, and overflow outlet for fluid and back-up supply source. A variable-displacement hydraulic motor mounted inside the power cab (atop the mast) employs a swashplate control and return valves to increase inherent system control and in some applications, may obviate the need for a separate viscous coupling. A water to oil heat exchanger assembly will be integrated into the hydraulic fluid return line to maintain hydraulic fluid temperatures within specified limits. The heat exchanger will be mounted alongside the radiator, which cools the natural gas engine.
Another advantage of using swashplate control and return valves is that these control mechanisms would allow the mainshaft to “freewheel” in the depressurized (0 swashplate angle) mode, reducing hydraulic fluid cooling requirements and overall drag on the system when under wind power. Similar control schemes are used in hydraulic systems and hydraulic-driven electrical generators in used in the constant-speed generators employed on many aircraft engines. A one-way check valve calibrated to the specific pressure needed by the propulsion unit will act as a safety override mechanism that shuts off hydraulic fluid flow from the pump if maximum pressure thresholds are exceeded. The check valve and incorporated pressure sensor simultaneously sends a cut-off signal to the natural gas engine to prevent damage to the accumulator tank and hydraulic lines from over-pressurization. The check valve will be incorporated on the pressure supply line.
The combination of the constant-pressure, variable-displacement hydraulic pump on the gas engine, with the constant-speed, variable-displacement hydraulic drive motor, each with individual controllers, would take care of all but the most excessive load/speed transients. The clutch/controller on the planetary gear set will act as a secondary mechanism to compensate for engagement load/speed transients above 150% of design load capacity (when the hydraulic motor is engaging and disengaging). Sudden, high-pressure shocks to the various connection joints and propulsion system could cause instantaneous component failure (metal fatigue or shearing) and certainly would reduce the service life of critical components. To ensure that hydraulic fluid used in the closed-loop system remains free of contaminants, an inline filter will be mounted on the return line as part of the base unit assembly—for ease of maintenance.
The hydraulic propulsion system will consist of a ring and pinion gear assembly, planetary gearbox to increase torque, viscous coupling and harmonic damping flywheel to absorb start/stop engine shock and sensors to monitor shaft speed. The ring gear is impelled by the rotation of the pinion assembly, which translates hydraulic pressure into (right angle) rotational force. The pinion translates right angle motion into torque which spins the ring gear which, in turn, spins the planetary gear assembly. The ratios for the planetary gear set may be varied as required to provide sufficient torque to spin the main generator shaft at specified RPM to meet specified output demand (rated power or peak usage demand). The entire hydraulic propulsion system, including the natural gas engine, is controlled by a series of speed sensors and auto start/stop actuators synchronized, programmed and controlled by the Master Control Panel to work in unison.
The hydraulic propulsion system would automatically send power via a viscous coupling and planetary gear set that engage and turn the electrical generator shaft when wind velocity isn't sufficient to ensure that main shaft revolutions per minute (RPM) remain within generator manufacturer's recommended speed range (minimum speed necessary to generate rated electrical output). The most likely condition causing the auxiliary propulsion system to engage would be insufficient wind velocity (calm days) or gusting velocities that exceed rated rotational speed of the propeller assembly (unpredictable weather/storm conditions), which would fail to turn the main generator shaft at the required RPM to assure specified/rated electrical output. A propeller feathering mechanism could also be incorporated to prevent damage to the large propeller assembly during extremely high winds (storm conditions).
The auxiliary propulsion system would be controlled by employing the latest technology available (sensors, controllers and actuators) that have accrued hundreds of thousands of hours of all-weather use in automotive and aircraft industry applications. Symmetrical sets of sensors, controllers and actuators would be mounted within a control box co-located with the natural gas engine and the hydraulic propulsion unit at the power generator base. The other set of sensors will be mounted on the hydraulic propulsion unit and generator main shaft in the power generation cab atop the mast assembly. All sensors will be capable of calibration to specific generator/applications, as needed and form integral components of the redundant system for shaft speed monitoring and control. The matched (paired) shaft-mounted components sense decreases in speed and provide commands to the natural gas engine/high-pressure hydraulic pump to engage, begin spinning the pinion gear and thusly rotate the ring gear, which is connected to the planetary gear assembly, which in-turn, propels the main shaft axially in absence of wind. This apparatus ensures instantaneous “on demand” power augmentation to maintain generator shaft RPM in the optimal electricity generating range (peak demand satisfaction or rated output) specified by the generator manufacturer. The sensors and actuators used are extremely rugged, small and have the added benefit of drawing very low voltage when in operation (12v DC).
If the generator shaft RPM drops below the lowest acceptable RPM for demand/rated power generation (250 RPM, for example), a series of redundant electro-magnetic induction (shaft) speed sensors mounted on the generator main shaft (FIG. #2, page 31) would immediately sense a reduction in shaft speed to below the calibrated rotational speed range and transmit an electrical signal to the main hydraulic propulsion system control unit, thereby triggering the natural gas powered aux engine to start-up, come on line and spin the hydraulic pump unit which would then provide a pre-specified volume of high-pressure hydraulic fluid via a delivery line to the hydraulic power unit mounted on center-line axis behind the electrical power generator.
The hydraulic pressure supplied to the power unit via the hydraulic pump would be translated into rotational force via a pinion and ring gear set or via a vaned turbine unit mounted on the generator mainshaft that is turned directly by hydraulic pressure from the hydraulic pump line. The vaned turbine unit would be a more compact and economical approach for low to medium power generation (10 kW to 100 kW range), while the ring and pinion application would be more suitable to megawatt range power generation requirements, because the gearset can be stepped as needed to match torque requirements to spin the electrical generator at the specified revolutions per minute (RPM) to produce rated electrical output.
The pinion gear would engage and turn the axially mounted ring gear which provides rotational force (torque) to the planetary gear system, viscous coupling box and damping flywheel. The aux engine and generator mainshaft will be fitted with electromagnetic (induction) rotational speed sensors and auto-start/stop technology (FIG. #2, page 31), that is very similar to the sensors and controller mechanisms currently employed in hybrid electric-gas automobiles to instantly start-up, engage and then cut-off when not needed, as well as activate and deactivate natural gas engine cylinders for optimum economy of operation during periods of light power demand by the electric generator.
This apparatus ensures instantaneous “on demand” power augmentation to maintain generator shaft RPM in the optimal electricity generating range (peak demand satisfaction or rated output) specified by the generator manufacturer. The sensors and actuators used are extremely rugged, small and have the added benefit of drawing very low voltage when in operation (12v DC).
Other key design features:
IV. Uses an aircraft style suspension mount (
V. Uses an automotive or industrial “on-demand” auto-start/cut-off switch), (FIG. #2, page 31), permitting the engine to instantaneously engage and supply hydraulic pressure when needed and also rapidly cut-off as wind conditions warrant;
VI. Employs a shaft speed sensing switch (FIG. #2, page 31), triggering the auto-start mechanism and engaging the engine/hydraulic fluid pump assembly to maintain adequate main shaft RPM when wind velocity isn't adequate to turn the generator;
VII. Uses a planetary drive and start-stop shock mitigating viscous clutch (FIG. #2, page 31), allowing the engine power supply shaft to freewheel without creating shaft drag when not needed;
VIII. Engine horsepower will be matched to the application and will depend upon size of the hydraulic pump and pressure/fluid velocity necessary to propel the wind generator and region of the country where deployed.
Typical electro-magnetic sensors calibrated to preset shaft speeds as described in Section 7 on page 15 and in (FIG. #2 on page 31), as attached to this submission.
Sensors detect shaft speed and send signals to control unit which then starts or stops the auxiliary engine as required.
