A number of dispensers have been proposed to distribute particulate material such as fertiliser as the device containing the dispenser is moved. Usually a wheel of the device causes relative rotation of plates at the outlet of the hopper for the material, the plates having orifices which are in and out of register as rotation occurs, thereby allowing a controlled amount of the material to be dropped.
German Pat. No. 2 444 285 (WOLLNER) relates to a silo outlet having a plate having orifices in direct communication with the material in the hopper. The material drops through the orifices on to a second plate spaced away from the first plate and a wiper blade causes the material deposited on the lower plate to be transferred to a central opening through which it drops by gravity. In this way a predetermined measured amount of the material can be delivered.
In German Pat. No. 2 731 798 (CHAMBON) a series of three plates is provided. These are movable relatively to one another, the arrangement being such that the orifices of the first plate register with those of the second plate when the latter are out of register with the orifices of the third (or lowermost) plate. Thus, the orifices in the second plate become full and further relative movement brings the orifice of the second plate into register with those of the third plate, the material falling through the latter orifices. Thus, an intermittent discharge of the material is obtained and while this may be satisfactory for certain purposes, it is not entirely satisfactory for all purposes.
Another patent which describes a dispenser which dispenses fluent material in an intermittent fashion is U.S. Pat. No. 2,207,822 (ROONEY et al). In this patent, there is an upper plate, an intermediate plate and a lower plate which is fixed with reference to the upper plate. The intermediate plate is rotatable relative to the upper and lower plates. Both the upper and lower plates have a single orifice while the intermediate plate has a plurality of orifices. During rotation of the intermediate plate, its orifices receive material in turn from the single orifice of the upper plate and then subsequently discharge that material in intermittent fashion as each of its orifices in turn registers with the single orifice in the lower plate. The material dropping through the lower plate falls into a vertical pipe feeding into a horizontal chute along which air is forced by a fan. The action of the fan is to spread the material.
In the case of a dispenser intended to dispense granular material such as fertilizer it is clearly undesirable to have an intermittent flow as would result from the Rooney apparatus in the absence of its fan. By the same token, the provision of a fan involves extra complications and expense.
It is the object of the present invention to provide a dispenser for granular and other fluent materials which has an assembly of upper and lower plates and a rotatable intermediate member, the dispenser operating in such a manner that there is a continuous, and not intermittent, dispensing of material through the lower plate.