Abstract:
A system for supplying heated milk or other liquids to individual drinkers from which animals, particularly baby pigs, can drink on a need basis by actuating a valve in the drinker that allows the milk to flow into the drinker. The system has a plurality of drinkers within a closed system in which the milk is supplied from a reservoir, heated to a minimum predetermined temperature range and pumped to each drinker which is positioned so that milk is continuously circulated through the drinker any time the circulating pump is running. This not only keeps the heated milk from spoiling, but it also prevents the drinkers from becoming clogged and permits the entire system to be cleaned in place.

Description:
BACKGROUND OF INVENTION 
   Livestock producers frequently utilize automatic feeding systems to assure that the animals, especially small animals, are always supplied with adequate feed for healthy and rapid growth. In the case of baby pigs, the feed is frequently supplied in a liquid form, usually milk or a milk replacer. The liquid feeding systems that are presently in use provide the liquid to individual drinker units from a supply tank, the drinker units permitting the animals to drink on a need basis by actuating a valve that allows the milk to flow into the unit. In presently known systems, each drinker unit is connected by a vertical line to an overhead trunk or supply line, the milk being supplied to each drinker unit. An example of such a system is shown in my U.S. Pat. No. 5,115,764. Although systems of this type assure a constant supply of the liquid feed to the animals, when the ambient air temperature is low and remains low for an extended period of time, the temperature of the liquid will also be lowered and may not be as palatable to small, baby animals who prefer warm, liquid feed. The baby animals may therefore not consume the amount of liquid feed desired for proper growth. 
   Therefore, there is a need for an improved system for supplying heated liquid feed to individual drinker units from a supply source, which system will provide the heated liquid feed to the drinker units at a temperature desired by the baby animals. 
   Because the liquid feed is circulated under pressure through all of the lines to prevent the liquid feed from remaining in any portion of the lines and thus becoming stale or clogging the lines, there is a need for a system in which the liquid feed is heated without creating a hazard if the controls should fail and the heating means fail to shut down at the proper time. 
   Because systems of this type must be regularly cleaned, and if difficult to clean may be neglected by the livestock producer, there is also a need for a heated system which can be easily cleaned in place. 
   SUMMARY OF INVENTION 
   The milk supply system of the invention is a closed, pressurized system in which each individual drinker is positioned in the system so that the liquid feed can be continuously circulated through the drinkers at all times when the circulating pump is running. The individual drinkers are serially connected in the closed, pressurized system and are supplied with fresh liquid feed from a supply source. A heating unit is included in the milk supply to the drinkers, and the pump and heating unit are interconnected so that heating unit is operable only when the pump is operating. Thus, heated liquid feed is always supplied in the closed system containing the drinker units. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a schematic view in perspective of the system of the invention; 
       FIG. 2  is an elevational view, partially in section, of the supply tank showing the position of the supply and return lines; and 
       FIG. 3  is a sectional view of an individual drinker unit. 
   

   DETAILED DESCRIPTION 
   Referring first to  FIG. 1 , the system of the invention provides for delivery of the liquid feed, such as milk, from a source contained in a supply tank  10 . The milk in tank  10  is circulated throughout the system by a circulating pump  12  through a supply line  14 . In  FIG. 1 , pump  12  is shown as a submersible pump and also as being located outside of tank  10 . Location of the pump  12  is preferably outside the tank  10  in supply line  14  for reasons explained more fully hereinafter. Supply line  14  follows a pattern consisting of a plurality of vertical loops as shown in  FIG. 1 . In other words, the supply line  14  carries the milk out of the tank  10  usually upwardly to an upper level several feet above the floor level of the building in which the system is installed, and then around the building at this upper level while dropping downwardly to the drinker units  16  positioned at or near the bottom of each of the vertical loops. The number and location of the vertical loops will depend in large part on the particular layout of the building in which the system is installed. The upper portions of the vertical loops have been termed the trunk lines  17 , and they are usually located near the ceiling of the building so as to be out of the way. As shown in  FIG. 1 , each vertical loop of the supply line  14  has a downwardly extending line  18  and an upwardly extending line  20  which are connected at their lower ends by a bottom line  22  in which is connected one or more animal actuated drinker units  16 . Although for purposes of description I have broken the supply line  14  into segments and applied descriptive terminology to each segment, it will be evident from  FIG. 1  that the supply line  14  is a continuous supply conduit through which the milk flows in the direction indicated by the arrows until the supply line  14  passes through the last drinker unit  16  from where the milk then flows through a return line  26  that extends to the bottom of the supply tank  10  ( FIG. 2 ). It is essential the portion of return line  26  following the last drinker unit  16  be at a level above the level of the discharge opening  37  from valve unit  32 . Also, as indicated in  FIG. 1 , there are a plurality of vertical loops in the supply line  14 , usually with one or more drinker units  16  in the bottom line  22  of each loop. The drinker units  16  normally are located at or near the floor level at a convenient height for the animals for which the system is installed. The drinker units  16  may be of any suitable type in which the animal actuates a valve to open the valve and allow the liquid to be released so that the animal can drink it. In  FIG. 3 , there is shown a preferred drinker unit  16  which is installed in the vertical leg  28  of a tee  24  in the bottom line  22  of the supply line  14 . Each drinker unit  16  has a cup  30  to contain the milk and a valve unit indicated generally by the reference numeral  32  The valve unit consists of a retainer  34  threaded into the leg  28 , the retainer  34  having a vertical passageway  36  with a discharge opening  37  at its upper end and an O-ring  38  at its lower end. Extending through the vertical passageway  36  is an actuator  40  which has a seat  42  that is engaged normally with the O-ring  38 , the seat  42  being normally held against the O-ring  38  by a spring  44  seated in a spring retainer  46  that is threaded into the lower end of the retainer  34 . Thus, when the animal moves the actuator  40 , the seal between the seat  42  and O-ring  38  will be broken, and the milk flowing through the supply line  14  will be allowed to flow into the cup  30 , since the milk is constantly under pressure. In this regard, the lowest level of the milk in the supply tank  10  is preferably above the discharge opening  37  from the vertical passageway  36 , and tank  10  therefore may be elevated on legs  39 . Referring now to  FIGS. 1 and 2 , it will be seen that the return line  26  terminates near the bottom wall  48  of the tank  10  so that the discharge end of the return line  26  should always be below the liquid level in the supply tank  10 . A pressure operated switch  50  is also provided to stop the pump  12  when the tank  10  is empty. This prevents the pump  12  from operating when there is insufficient liquid in the tank  10  thereby preventing damage to the pump. 
   When the system is used to feed baby pigs, it is important to have the liquid feed, such as milk, at a temperature greater than about 70° F. If the milk is too cool, the baby pigs won&#39;t drink as much as they should. Therefore, there is provided in the system a means to heat the milk to the desired temperature. In one embodiment, the pump  12  is located outside the tank  10  rather than in the tank  10 , and an immersion heater  70  is positioned in the tank  10  or in the supply line  14  upstream from the pump  12  and downstream from the tank  10 . The immersion heater  70  is of any suitable type well know to those skilled in the art in which the heating element is submerged in the liquid flowing through the supply line  14 . Such heaters are typically thermostatically controlled. In another embodiment, a heater  72  is positioned along the supply line  14 . In the embodiment shown in the drawings, heater  72  is positioned downstream from the pump  12  and ahead of the first drinking unit  16 , but it will be understood that heater  72  can be positioned anywhere in the supply line  14  and that there may be more than one heater  72 . Heater  72  is preferably of the resistance-heating cable type that can be wrapped around the outside of the portion  17  of the supply line  14  close to the first drinking unit  16 . With this type of heater  72  the heating cable can be wrapped around the supply line  14  at a spacing that will provide the desired means to heat the milk flowing through the supply line  14  to the desired temperature. Moreover, the rope type heater  72  provides flexibility because this type of heater can easily be located in more than one place along the supply line  14  of the system. In large systems with numerous drinker units  16 , more than one heater  72  may be necessary to maintain the desired milk feeding temperature to all the units  16 . However, it is also important not to overheat the milk or it can burn, affecting the taste and possibly injuring the baby pigs. 
   It will also be understood that the tank  10  can be externally heated or the milk can be preheated and supplied to the system. It is important only that the milk be at the proper temperature when it reaches the drinking units  16  and heated at a rate that does not damage the milk. 
   With the addition of a heater  70  or  72  into the system, the heaters preferably are connected so as to be energized only if the pump  12  is operating, since it is important to heat milk only if it is flowing through the system for feeding, unless the heater  70  is immersed in the tank  10  and is thermostatically controlled. If the heaters are on and not thermostatically controlled, and the milk is not circulating, the milk can be damaged and may plug the lines. 
   Also, with reference to  FIGS. 1 and 2 , there is illustrated as a part of the schematic of  FIG. 1  a valve arrangement which permits the system to operate efficiently with a smaller less expensive pump, and which also provides the means for conducting a thorough cleaning and rinsing of the entire system in a simple, efficient and easy-to-operate manner. In  FIG. 1 , there is shown a valve  52  in the supply line  14 , the valve  52  being upstream from all of the drinker units  16  Similarly, a valve  54  is located in the return line  26  just upstream from where the return line  26  discharges into the tank  10 . In order to provide for cleaning the system and for purging air from the system, a water supply line  56  is connected to a pressurized external water source, the line  56  being connected to the milk supply line  14  downstream from valve  52 . Water supply line  56  also contains a valve  58  so that the supply of water through line  56  can be controlled. Similarly, a drain line  60  is connected to the return line  26  just upstream from the valve  54 , the drain line  60  also containing a valve  62 , with the drain line  60  discharging into a suitable drain. The various valves just described can be manually operated, or if desired, the various valves can be automatically operated according to a predetermined program dictated by a control system (not shown). Such a control system does not form a part of the invention, since such a system is within the skill of a person ordinarily skilled in the art knowing the desired sequence of operation. If the system is not in use, normally all four valves  52 ,  54 ,  58  and  62  will be closed. Before placing the system in operation, it is important that the supply line  14  and return line  26  be free from any air pockets Therefore, the drain valve  62  and water supply valve  58  are opened while keeping the valves  52  and  54  closed. Valve  52  is momentarily opened to allow a small amount of water to flow back through pump  12  and purge any air in the portion of supply line  14  between the valve  52  and supply tank  10 . Valve  52  is then closed to allow the water from the external water supply source to flow through the entire system and be discharged through the drain line  60  into the drain. Flow of the water should be continued until no air bubbles are visible at the drain. At this time, the water supply valve  58  is closed. The tank  10  is then filled with the desired liquid feed, such as milk, and the circulating pump  12  started. Simultaneously with the starting of the pump  12 , the valve  52  in the supply line  14  is opened. This allows milk to start flowing through the supply line  14 , and since the valve  54  is still closed, the liquid in the supply line  14  will be discharged from the drain line  60 . Of course, when the pump  12  was started, the supply line  14  was filled with the water used to purge the system, and therefore the operator should observe the liquid being discharged from the drain line  60  until all of the water has been discharged and milk is being discharged into the drain. At this time, valve  62  is closed and valve  54  opened. As long as there is sufficient milk in the tank  10 , the milk will continue to be circulated throughout the system through supply line  14  and return line  26 . Unless the level of milk in the tank  10  falls below the level controlled by the pressure controlled switch  50 , the circulating pump will continue to run. Thus, the milk will be continuously pumped through the system and through each of the drinker units  16 , thereby preventing any of the milk from sitting at any point and becoming stale. 
   Periodically, it is necessary to clean the system. This is done in the following manner. With the valves  52  and  62  open and valves  54  and  58  closed, and with the pressure controlled switch  50  activated, all of the milk is pumped from the system and from the tank  10  through the drain line  60 . If desired, this milk could be discharged from the drain line  60  into a container for future use. In any event, the pump  12  is operated until such time as milk is no longer being discharged from the system. At this time, the pump  12  is shut off. If desired, the tank  10  can be rinsed in any suitable manner using, for example, a hose connected to a water source, after which the rinsing liquid is either manually drained from the tank  10  or drained using the circulating pump  12 . The valve  52  is then closed and the water supply valve  58  opened. With valve  54  still closed and valve  62  and the drain line  60  open, the system is flushed by allowing the water from the pressurized water supply to flow to flow into the system through water supply line  56 . Flushing with water should continue until the operator determines that the system has been adequately flushed. Then, the water supply valve  58  is closed and the valve  52  in the supply line  14  opened. In order to remove all residue of the liquid feed from the system, a liquid cleaning solution may be added to the tank  10 , the pump  12  started and valve  54  opened and drain valve  62  closed. This cleaning solution is circulated throughout the system for the desired amount of time. To discharge the cleaning solution from the system, valve  54  is closed and drain valve  62  opened. While the cleaning solution is being discharged into the drain, the tank  10  may be rinsed in any suitable manner, such as by using a hose connected to an external water supply. After the tank  10  is rinsed and emptied by pump  12 , the pump  12  is stopped, valve  52  closed and water supply valve  58  opened to flush the entire system with fresh clean water. As soon as the water being discharged from the drain line  60  is clear, drain valve  62  is closed and valve  54  opened momentarily to flush that portion of return line  26  downstream from valve  54 . Then, all the valves are closed and the system is again ready for use. 
   Periodically, the drinker units  16  may be cleaned by either removing them and cleaning them or by manually moving the actuator  40  in each drinker unit  16  during the cleaning cycle. If the drinker units  16  are left in place for cleaning, the cups  30  can be manually flushed in any suitable manner, such as by pressure washing at the time the facility is cleaned. 
   It will be evident from the foregoing description that the system of the invention provides for continuous circulation of the liquid feed or milk throughout the system thereby preventing the milk from ever becoming stale. Usually, the room temperature in a building where a system like this is installed is around 72 degrees, but if needed because the liquid feed temperature drops, the heater  70  or heater  72  may be turned on while the pump  12  is operating. As long as an adequate amount of milk is maintained in the tank  10 , the supply line  14  will always be full, and since the milk in the line is always under a slight pressure, there is no place in the system where the milk can become at rest and become stale. Also, the system lends itself to easy and thorough cleaning in place with the valve arrangement described. 
   Although the system of the invention has been described in connection with preferred embodiments thereof, it will be evident to those skilled in the art that various revisions and modifications can be made to the preferred embodiments without departing from the spirit and scope of the invention. It is my intention, however, that all such revisions and modifications as are obvious to those skilled in the art will be included within the scope of the following claims.