This invention relates generally to a combination weighing machine and, more particularly, to a product feeding and weighing structure for such a machine.
It is a common practice to increase the number of weigh hoppers for improving the accuracy of combination weights in a combination weighing machine. However, it is not always necessary to provide each weigh hopper with a feed hopper for feeding product to the weigh hopper since each weigh hopper is not emptied every combination cycle. Therefore, it has been proposed to associate a single feed hopper with a plurality of weigh hoppers. Japanese utility model opening gazette Nos. 60-17419 and 60-17420 disclose such product feeding and weighing structures. In the disclosed structures, each of the weighing heads includes a pair of weigh hoppers arranged side-by-side and a common feed hopper disposed above these weigh hoppers. The feed hopper is arranged to move between the pair of weigh hoppers to feed product selectively to either one which has been unloaded and is thus empty.
However, the disclosed structures have disadvantages. For example the increased number of weigh hoppers also increases the number of expensive delicate weighing units. Also the distance between the weigh hoppers of each pair requires a substantial travel time for the feed hopper, which results in undesirable reduction in the machine operation speed.