The field of the invention is irrigation systems.
Underground irrigation systems are used to water lawns and gardens at homes and businesses, as well as larger areas such as parks and golf courses. Systems known in the prior art use a controller which is wired with low-voltage multi-strand wire or multiple single-strand wires which runs through the ground to a series of valve boxes. Each valve box contains valves that are activated by a solenoid. For golf course applications, each solenoid is built into its corresponding valve instead of having several valves in a valve box activated by one solenoid. When the valves are opened, water flows through irrigation pipes to the area (called a zone) of the lawn or garden that is to be irrigated.
The biggest type of multi-strand wire has thirteen strands, and only one of these strands is used as the common input wire in the controller. This limits the number of zones that can be watered. For example, with thirteen-strand wire, one wire is the common wire, leaving twelve wires to each service a zone. Thus the maximum number of zones that can be irrigated using one controller is twelve.
In the prior art, controllers use a separate wire for each zone and have one common wire. Expandable controllers have a base with one common wire and three zone wires, and are expanded by adding as many modules of these zone wires as are needed.
Examples of prior art irrigation systems are disclosed in the following U.S. Patents: U.S. Pat. No. 4,985,638 to Brock, U.S. Pat. No. 5,048,755 to Dodds, and U.S. Pat. No. 5,662,135 to Oppman et al. No known prior art discloses the type of system used in the present invention.
The invention is an irrigation system that has more than one common wire (therefore multiple inputs to the controller). A simple example is a controller having five-strand wire. Two of the wires are common wires, while the other three wires are zone wires (also known as field wires), each serving two zones, for a total of six zones. Adding more common wires increases the number of zones; for example, six strands of wire for nine zones, seven strands of wire for twelve zones; this pattern can continue indefinitely.
An advantage of this system is that more zones can be served with fewer wires and connections, since the zone numbers are set with multiple common wires instead of one common wire with multiple zone wires. Especially with a large lawn, this greatly reduces the expense and labor involved in laying the wires for the system.