This invention relates to a system which is used to displace a fluid which varies greatly in consistency. The invention is particularly useful in loading manure into a manure wagon.
Difficulty arises in attempting to load manure from a pit in which it is contained into a manure wagon used to transport the manure due to a tendency of the solids within the manure to settle toward the bottom of the pit. Most of the more liquid portion of the manure is displaced toward the top of the pit as the solids settle toward the bottom of the pit, causing the manure to vary greatly in consistency and rendering it difficult to pump or otherwise remove the manure from the pit.
A pump type vacuum device used in combination with a vacuum power assist auger has been found to effectively withdraw manure from the pit in which it is contained. The vacuum power assist auger described may be identical to that described in my prior U.S. Pat. No. 4,661,046. The vacuum device withdraws the liquid portion of the manure from the pit easily, while the vacuum power assist auger helps to withdraw the more solid, settled portion of the manure. However, it has been found that the settled solids at the bottom of the pit, which are withdrawn by the auger, tend to clog some types of vacuum devices, that are used for top loading which in turn may cause the vacuum power assist auger to overload. Accordingly, a pump type vacuum device which is least likely to clog when used in conjunction with a vacuum power assist auger is needed.
U.S. Pat. No. 4,531,892 discloses an apparatus for pumping pulp including motors 5 and 13 for driving screw 9 and impeller 3, respectively. Impeller 3 is driven at a higher revolution rate than screw 9. The capacity of screw 9 is adjusted to exceed the capacity of the pump of the apparatus so that recirculation of pulp between the screw thread and the axle is effected. The risk that the apparatus will clog is therefore reduced. However, if the apparatus disclosed by this patent were used to displace a very thick material, impeller 13 would still tend to clog, since a thick material would freely flow between the screw thread and the axle. Additionally, since pulp recirculates between the screw thread and the axle of the apparatus, this particular pump tends to be inefficient.
U.S. Pat. No. 4,594,006 discloses a mixing and pumping apparatus including a shaft 20 and pumping screw 22. As shaft 20 is rotated, crust at the surface of the slurry contained in reservoir R will be forced downwardly by screw 22 and mixed in with the rest of the slurry, thereby allowing the slurry to be pumped from reservoir R more quickly. The apparatus also includes agitator jet nozzles for further mixing the slurry.
By utilizing a pumping system in which the tendency of the system to clog is minimized, the need for mixing devices such as that illustrated by this patent may be eliminated.