Patent Application
20100288375
The present invention relates to the field of water conservation and more particularly devices and methods for irrigating plants and outdoor water use. More particularly it relates to devices and methods for storing and optimizing spray irrigation regardless of water levels in the system by maintaining a constant pressure via gravity to a sprayer connected to a hose and used for outdoor washing, or irrigation of landscapes or gardens.
Many areas of the United States experience frequent shortages of fresh water. Degradation of water supplies are also becoming increasingly prevalent and are often difficult and expensive to remedy. Such degradations are often related to the proliferation of impervious (paved or constructed) surfaces by both preventing the natural recharge of groundwater resources while exacerbating flooding problems, in-stream erosion, storm water runoff, and increasing frequency of Combined Sewer Overflow (CSO) discharges.
For the watering of plants around a dwelling or other structure, several systems and/or methods are commonly used. These include dedicated watering lines (e.g., drip irrigation), area distribution devices (e.g., sprinklers), moveable hoses, and watering cans.
Because sprinklers, drip systems and water cans have limitations and are designed for specific uses, most gardeners utilize portable hoses to water plants in the garden. The hose can be moved from plant to plant to provide an optimal amount of water. However, many hose systems are connected to the house water supply and therefore deplete potable water resources. It is well recognized in the art that there are numerous stresses on fresh water supplies including greater demand, quality degradation, and lack of conservation. Because of concerns over conservation of potable water resources, the use of rain water runoff for uses such as irrigation, car washing and outdoor use, often referred to as “rainwater harvesting,” has become increasingly popular. Through rainwater harvesting devices and systems, the demand on other sources of water is reduced.
One method of rainwater harvesting is through the use of a rain barrel storage and irrigation system. The use of rain barrels and cisterns are known in the prior art. U.S. Pat. No. 7,025,076 describes a rain barrel used for the collecting and dispensing rainwater and a rain water cistern. It is understood by those skilled in the art that a rain barrel is used as the water source. And it will be understood by those skilled in the art that rain barrels include large barrels or other containers. Throughout this application rain barrel, water storage vessel, and cistern may be used interchangeably. Such rain barrels can be located, for example, in proximity to a house's gutter downspout to collect rain water for later use. In other examples, the rain barrel can be located further from the down spout. For example, there is a flow control mechanism described in U.S. Pat. No. 6,619,312 that enables a rain barrel to be positioned at a distance from the downspout.
In addition to the foregoing, the rain barrel may have a drain valve which those of skill in the art will generally understand as a spout/spigot that is attached generally to the lower portion of the rain barrel to allow the collected water to flow out for use. Optionally, a hose can be connected to the spout/spigot so that the water can be used for irrigation and other outdoor household uses to provide a rain water harvesting device. There are, however, limitations to using a rain barrel for irrigation. One such limitation is that without replenishment through rainfall, water level declines and results in lower water pressure thereby causing a lower and slower flow rate from the drain valve. In such a circumstance, more time is required to allow a desired volume of water to be discharged.
In cases where the water is to be used for spray application such as for a lawn sprinkler, garden watering tool (e.g. U.S. Pat. No. 5,782,412), or vehicle or other outdoor washing device (e.g. U.S. Pat. No. 1,097,410), the water is commonly dispensed through hoses with pressure provided either by gravity from a stationary rain barrel or an active pump. For such applications, certain minimum pressures are necessary. A rain barrel equipped with a mechanical pump such as the one disclosed in U.S. Pat. No. 7,025,879 is capable of providing such a consistent pressure, but requires an external power source and additional maintenance for operation.
When provided by gravity from a conventional stationary rain barrel, the pressure at the spray head varies with the volume contained in the vessel, and consistently declines as the water is drawn off through the sprayer. The pressure in such a system at any particular time is a function of the total head in the system which is the sum of the pressure head, elevation head and velocity head at given point within the system. The relationship is represented by Bernoulli's Equation, below.
In a rain barrel resting on or near the ground (z˜0), the total head or energy consists exclusively or nearly exclusively of the pressure head term, . At the spray head, the total head is equal to that in the barrel but consists predominantly of the velocity head,
manifested as spray “pressure” from the device.
Following draw off of a given water volume, a new equilibrium energy state is achieved across the system, with the total head less than that in the system originally. In this new state, the pressure head in the barrel is lower, and the velocity head realized at the spray head or hose end is reduced.
Although lower in the second emptier system containing less water, it can be shown by Bernoulli's Equation that the total head in the system can be made equal to the previous system containing more water by increasing the elevation head or z term.
While the aforementioned prior art rain water harvesting devices fulfill certain objectives and requirements, a need exists for a rain water harvesting device that can provide water under a constant, desired pressure for spray applications, without the use of a pump or other similar externally-powered mechanical device, regardless of the volume collected or previously dispensed. The current invention solves this problem with a device and system designed to maintain an optimal water pressure regardless of the water level in the rain barrel. The invention meets the needs presented above by providing water at constant pressure via gravity to a sprayer system.
To this end, an optimal embodiment of the invention comprises a rain storage vessel, optionally contained in a rack, and connected to a spring that assists with vertical migration of the rain storage vessel. In one embodiment, the vessel rests on at least one compression spring, supported in turn by the ground or a base that sits at the bottom of the rack. When the vessel is at or near capacity and the pressure head represented by the static water level is adequate, the vessel represents a maximum opposing force on the spring, compressing the spring to a point where the pressure head and nominal elevation head represented by the top of the fully compressed spring are equivalent to the desired head at the sprayer consistent with Bernoulli's Equation. During periods, however, when the water supply in the rain barrel has been depleted or during periods when less water has been collected, the lesser opposing force of gravity acting on the lighter vessel results in the mechanical force of the spring raising (or in the case of a tension spring lifting) the vessel and thereby increasing the elevation head and maintaining pressure to irrigation spray head. In one example,
Rearranging Bernoulli's Equation above, and keeping velocity head term
constant, the equation becomes:
Referring generally to ) declines along with the decreasing static water level in the storage vessel to maintain the constant velocity head (i.e. water velocity or flow at the drain valve).
In the various figures, exemplary features of the invention are demonstrated so that the detailed description that follows may be better understood, and that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto and in no way should the following figures and examples limit the scope of the invention as would be understood and appreciated by those skilled in the art. Finally it will be understood that the aforementioned references are incorporated by reference.
Referring back to the exemplary embodiment of
In one embodiment of the invention, the use of a pulley and counterweight system is envisioned that would act in the same manner as either of the spring configurations discussed above to raise the vessel during periods of low capacity. In such a pulley system the invention contemplates the use of a two-vessel and pulley system whereby the vessel containing more water acts as a counterweight to lift the vessel containing the lesser volume to the necessary height. Water would be alternately distributed to and from the vessels. In an another embodiment, it is envisioned that the base could have a mechanical hand operated apparatus that could be used to manually raise the storage vessel and that such operation could operate independently or be part of a spring system.
Other embodiments of the irrigations system are contemplated to include a backup water supply to the vessel which would act to fill the vessel during periods when the capacity is no longer sufficient for its intended use; the backup could be automatically triggered when capacity falls below a desired threshold volume. It will also be understood by those of skill in the art, that for certain uses, fertilizer or other chemicals may be added to the water supply contained in the water storage vessel for use in certain applications. In yet another contemplated embodiment, a water purifier could be hooked up to the irrigation system. In another envisioned embodiment, insulation or heat supply such as solar and/or electric to allow use when outdoor ambient temperatures are below freezing. An overflow port from the vessel to allow spillover during periods of excess inflow from precipitation is also envisioned in the context of the current invention. In another embodiment, the rain barrel in the irrigation system can be positioned at a distance from the downspout as is described in U.S. Pat. No. 6,619,312. Another envisioned embodiment of the invention would include a system where the base (11) shown in
Since certain changes (including those listed above) may be made in the above described embodiments, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.
