Abstract:
An apparatus for watering plants has a movable beam carrying several valves for dispersing water. At least some of the valves include a mechanism for sensing water flow and a regulator for adjusting the degree of opening of the valve until the actual flow corresponds to a selected flow value which is determined by a central control unit.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to an apparatus for watering surfaces, in particular plants, with at least one moveable beam on which are arranged several valves for dispensing water, the degree of opening of which can be adjusted continuously. 
     Such apparatuses are used in particular for watering plants, mainly on large-area flat surfaces, and the moveable beam can rotate around a central point of rotation or move in a linear manner. There are also hybrid forms in which the beam firstly moves in a linear manner, then changes to a rotary motion, and lastly moves in a linear manner again. With all these apparatuses for watering plants, it is important to apply a correctly metered amount of water to the ground. It is already known in this context to use valves whose flow is continuously adjustable (variable proportional valve) in contrast to on-off valves that can just be opened. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to improve an apparatus of the type described hereinabove to the extent that the amount of water dispensed by the individual valves can be determined in a precisely metered manner. 
     According to the invention, this is solved in that at least some of the valves are each provided with means for direct or indirect sensing of an actual flow value, and an electronic regulating means that regulates the degree of opening of the valve until the actual flow value corresponds to a reference flow value pre-determined by a central control means. 
     Thus it is not simply a case of transmitting an adjustment value for the valve member to the valves, as with decreasing pressure conditions in the water supply line for the different nozzles and the initial positioning of the valve member, this would lead to less exact flow control. Instead, the flow is regulated at the site of the valve, in that an actual flow value is detected and the valve member adjusts the degree of opening of the valve by means of an integrated electronic regulating means until the reference flow value pre-determined by the central control means is actually obtained. As with a known outlet nozzle size and with a known ambient pressure, the flow is a direct function of the pressure after the valve member or respectively in front of the outlet nozzle, there is an advantageous possibility that the flow regulation in the valve can take place by means of pressure regulation, wherein a unit converts the reference flow value, by means of further parameters such as the diameter of an outlet nozzle and/or the external air pressure, into a reference pressure value, and the regulating means adjusts the degree of opening of the valve until the actual pressure value detected by the pressure sensor corresponds to the reference pressure value calculated. 
     A sturdy valve that has no sealing problems is characterised in that it is provided with an elastic hose, wherein a valve member acting externally upon the hose compresses it and the flow is adjustable by means of the variable pinch point thus formed in the interior of the hose. 
     Further advantages of the details of the invention will be explained in more detail with reference to the following description of the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows in a schematic view from the side, an embodiment of an apparatus according to the invention for watering (sprinkling) plants. 
     FIG. 2 shows an embodiment of a valve together with regulating means according to the invention. 
     FIG. 3 shows a second embodiment of such a valve. 
     FIG. 4 shows an adjustment means for a valve according to FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The apparatus shown in FIG. 1 for watering plants is provided with a beam  3  (for example, a girder) arranged to rotate in the direction of the arrow  2  mounted on a central post  1 . Said beam is supported on rollers  4 , which may be driven in order to allow rotary motion about the central post  1 . The rollers in this case travel on the floor  5 . At the ends of a water supply system, valves  6  are provided, which are fitted with nozzles following on from them. The flow of these valves  6  can be adjusted selectively by means of a wiring system, not shown, for example a special bus system, of a central electronic control means  7 . The supply of water is via the central water connection  8  and water supply lines in the usual manner. 
     FIG. 2 shows an embodiment of a valve according to the invention together with regulating means. According to the invention, this valve  6  is provided with an apparatus  9  for direct detection of an actual flow value of the water flowing through. In the embodiment shown, this is a small impeller  9   a  and a small generator  9   b . The impeller rotates at different speeds according to the flow (volume per unit time), and provides a signal via the generator to the line  10 , which signal is proportional to or at least a function of the actual flow value Q ist . 
     According to the invention, the valve  6  further has an electronic regulating means  11 , wherein the actual regulator  12  compares the actual flow value detected with a reference flow value pre-determined by a central control unit  7  and provided via a wiring system, for example a bus system  13 . Depending on these initial values, the regulator then switches on the displacing motor  14  for the member  15  that is configured in a plate-like manner, and restricts the small diameter of the valve until the actual flow value corresponds to the pre-determined reference flow value. This is thus a sub-regulator, integrated into the valve, that ensures that the reference flow value pre-determined by the electronic control means is actually maintained and is independent of all external influences. 
     In the embodiment shown in FIG. 2, the water exits via an outlet nozzle  16  with diameter d. 
     FIG. 2 is to be understood as a schematic drawing. The electronic regulating means  11  can naturally be arranged directly on or respectively in the housing of the valve  6  to save space. The plate-like valve member  15  is to be understood as only a schematic representation. Clearly, it can be differently configured to obtain a compact design. Naturally, valve members other than plate-like valve members are perfectly conceivable and possible. It is advantageous when the electronic regulating means and the plate control are assembled with the remaining components of the valve to form a compact, replaceable valve. 
     In the embodiment shown in FIG. 3, flow regulation is done indirectly by means of pressure measurement. The valve shown in FIG. 3 is a so-called hose valve, in which a sealed, flexible hose  17  is provided internally. This hose  17  is provided between the entry point  18  with a connector  19  and the outlet nozzle body  20  with the outlet nozzle  16  (diameter d). All the previous sealing problems are avoided by means of this hose. The valve member  15  presses, at the point  21 , externally on the hose, and, as shown in broken lines, can press it inwards, whereby the flow is reduced. A preferably electric drive  22  is provided for driving the valve member  15 , which drive acts upon the valve member by means of a lever rod  23 . In order to support the movement of the valve member, there are provided a pressure equalizing line  24  and a membrane  25 , so that the valve member  15  is easily moveable. For regulation, in accordance with the invention, of the valve, a pressure sensor  9 ′ is provided, which is arranged on a point  17   a  of the hose that has a reduced wall thickness in order to make possible precise transmission of pressure of the internal water pressure to the pressure sensor  9 ′. The pressure sensor  9 ′ is connected to the adjustment means  11 . The adjustment means  11  is again directly attached to the housing of the valve. The circuitry can then be configured as represented in FIG.  4 . 
     In the regulating means shown in FIG. 4, flow regulation is done in the valve  6  indirectly by means of pressure regulation. In addition, the reference flow value Q soll  pre-determined by the central control unit  7  is firstly calculated with additional help from external parameters such as the air pressure p o  and diameter of the outlet nozzle  16  ( d ). This is done in the computer  26  which continually determines a reference pressure value p soil  from the reference flow value Q soll . The actual regulator unit  12  now adjusts the plate  15 , not shown here, by means of the motor  22  until the actual pressure value (p ist ) detected by the pressure sensor  9 ′ corresponds to the reference pressure value (p soll ). Flow regulation can be obtained in a simple and elegant manner by means of such pressure regulation. The outlet diameter of the outlet nozzle has just to be known. This is easily possible in accordance with the invention, as the outlet nozzles for all the valves, or respectively for large groups of valves can be constant and equal. 
     With the apparatus according to the invention, any water distribution quantity profile can be set up over the length of the beam, which profile can also be changed over time during operation. 
     Clearly, the invention can be employed with valves other than the valves used. The sprinkler system does not have to be a rotating sprinkler system, but instead beams that can be moved in a linear manner or in a linear and rotary manner can be provided. Moreover, it is perfectly conceivable to connect more than one outlet nozzle, that is to say a group of nozzles, to a valve, so that the outlet nozzles of one group can be controlled via one valve.