| 摘要 |
The specification discloses waterflow-controlling apparatus for an automatic irrigation system of a simple type including a single moisture-sensing means and one or more automatic sprinklers or other watering means controlled thereby or a plurality of such units together comprising a substantially larger automatic irrigation system. The waterflow-controlling apparatus includes one or more of the moisture-sensing means referred to above operatively controlling one or more waterflow-controlling means, such as valve means, in a water supply line feeding water to one or more sprinklers or other irrigating outlets, with each such moisture-sensing means comprising a hollow cell having a water-permeable wall in water-transmissive relationship with an adjacent porous medium which, in one form, includes a main medium such as a body of earth and in another form includes such a main medium and intermediate medium such as diatomaceous earth or other porous, water-holding and water-transmissive medium, which in one form is disclosed as having its water permeability controllably adjustable. The transmission of water in or out of the cell of the mositure-sensing means produces a corresponding interior pressure variation which effectively operates the water-flow-controlling valve means in a waterflow-producing direction either directly, through water pressure operated servo means, electrical servo means, or otherwise, when the moisture content of the earth adjacent to the moisture-sensing means falls below a predetermined value and, conversely operates said waterflow-controlling means in a waterflow-reducing direction when the moisture content in the earth adjacent to the moisture-sensing means rises above a predetermined value. In one form of the invention, the inverse feedback nature of the moisture-sensing and waterflow-controlling operations is of a continuous, inversely proportional nature rather than of an on-off nature.
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