When animals are kept as domestic pets or farm animals and the like, there is a need to provide them with a supply of fresh water for drinking. The water is usually contained in a reservoir, such as a trough or a bowl, which is typically made accessible to the animal so that the animal can drink water when ever it so desires. The water level in the reservoir will fall as the water is consumed by animals and/or by evaporation until the reservoir is completely empty. As the water is consumed it may become stagnant or unsanitary if not replenished or the concentration of existing and introduced contaminants increases as the water level decreases.
Thus, concerns of ready availability and cleanliness of animal drinking water require that the water reservoir be filled or nearly filled with fresh water at all times. This may be accomplished by several methods. These methods include, for example, maintaining a constant flow or trickle type system to fill the reservoir, manual filling or employing automatic control devices for sensing the level of water in the reservoir and actuating a flow control valve to replenish the water in real time or after the level has dropped to a certain predetermined level.
The constant flow method is often wasteful due to overflow that occurs and leads to untidy and possibly unsanitary conditions around the watering reservoir. Manually filling the reservoir when necessary is effective but time consuming and inconvenient. Using automatic control devices, then, is a practical solution to the problem of maintaining a level of water in a watering reservoir.
Automatic fluid level control devices are well known in the art. Several of these devices include float and valve mechanisms that typically employ a float to sense the level of water in a reservoir and actuate the valve mechanism by mechanically transmitting the buoyancy forces exerted on the float to the valve mechanism to open and close the valve to replenish water in the reservoir. The prior art control devices include, among other elements, a beam supported at a mechanical pivot point on a pivot pin with a float mounted at one end of the beam and an operative portion of the valve apparatus at the other end. The mechanical advantage provided by the beam is utilized to enhance shut off forces applied to the valve.
These devices are effective at controlling the level of a fluid in a reservoir; however, they tend to be difficult to adjust because of the long length of the beam necessary to generate proper shut-off forces and variations in water supply pressures that exist for a given application. The long beam length also prevents these devices from being small or compact since their size is somewhat determined by the length of the beam mechanism. The float and beam designs also are particularly susceptible to perturbations or rapid changes in the water level which may occur while an animal consumes water. Since valve sealing is enhanced by the buoyancy forces acting on the float, those forces being a function of the water level, changes in water level that can result from perturbations of the water may cause the valve to unseal and allow water to overfill the reservoir. The float and beam devices also tend to be mechanically complicated due to the mechanical linkages and the many parts required by their design and thus also tend to be relatively expensive. It would be desirable to have a watering reservoir including an automatic control device to sense the level of water in a reservoir and to actuate a flow control valve to maintain the level of fresh water in the reservoir that is simple in design and low in cost, relatively insensitive to perturbations in the water level and water supply pressure levels and easily adjustable to provide a desired fluid level in reservoirs of various sizes and shapes.