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    Moisture responsive apparatus for controlling moisture content of soil
    3.
    发明授权
    Moisture responsive apparatus for controlling moisture content of soil 失效
    用于控制土壤水分含量的水分响应装置

    公开(公告)号：US3874590A

    公开(公告)日：1975-04-01

    申请号：US40792873

    申请日：1973-10-19

    申请人： GIBSON WILLIAM H

    发明人： GIBSON WILLIAM H

    IPC分类号： A01G25/16 ,  A01G27/00

    CPC分类号： A01G25/167 ,  Y10T137/189

    摘要： A moisture responsive apparatus is disclosed for automatically controlling the operation of a soil irrigation system. The apparatus includes a moisture sensor having a perforated tubular sensing element adapted to be placed in contact with or in proximity to the soil and made of a material, such as nylon, that absorbs moisture and thereupon expands in accordance with the amount of moisture absorbed. The expansion and contraction of the sensing element relative to a member whose dimensions are unaffected by moisture are used to operate a pilot valve which in turn supplies a small control flow that actuates an irrigation system valve means. The sensing element and related member may have substantially the same coefficient of thermal expansion to compensate for dimensional changes due to temperature variations, and further may be adjustably coupled to permit setting the moisture content operating limits of the pilot valve. The sensing element may comprise a plurality of concentric, serially connected sensing tubes to increase the sensitivity of the sensing element for a given overall length. The sensing element may furthermore include reinforcing ribs projecting from the exterior surface thereof and may further be isolated from direct contact with the soil by means of a moisture-permeable screen disposed about the element but out of contact therewith.

    摘要翻译： 公开了一种用于自动控制土壤灌溉系统的操作的湿度响应装置。 该装置包括一个湿度传感器，其具有穿孔的管状感测元件，该多孔管状感测元件适于放置成与土壤接触或接近土壤并由诸如尼龙的材料制成，其吸收水分，随后根据所吸收的水分量而膨胀。 感测元件相对于尺寸不受潮湿影响的构件的膨胀和收缩被用于操作先导阀，导阀又提供致动冲洗系统阀装置的小的控制流。 感测元件和相关构件可以具有基本上相同的热膨胀系数以补偿由于温度变化引起的尺寸变化，并且还可以可调节地联接以允许设定先导阀的水分含量操作极限。 感测元件可以包括多个同心的，串联连接的传感管，以在给定的总长度上增加感测元件的灵敏度。 感测元件还可以包括从其外表面突出的加强肋，并且可以通过围绕元件设置但不与其接触的透湿屏蔽进一步与土壤直接接触隔离。