With conventional sieve cleaners, the cleaning devices are not constantly in contact with the sieve covering, but the cleaning effect is created essentially by the cleaning devices hitting against the sieve covering. This is facilitated, for example, by the fact that the sieve cleaner rests with one foot on an ondular grid arranged in parallel to the sieve cleaner, which is set vibrating as it moves across the ondular grid.
A conventional sieve frame has a sieve cleaner tiltingly supported with its foot on the bottom of the frame such that, at any given time, only a part of the cleaning brushes engage the sieve covering. Another sieve cleaner is known which has the form of a three-armed star whose cleaning devices are arranged in the area of the free ends of the three cantilever arms arranged in an angular distance of some 120 degrees. This sieve cleaner rests on the level sieve bottom with one foot so that, with the shaking motion of the sieve, the sieve cleaner executes a wobbling movement and hits the sieve covering. The foot can engage in a bottom-clearing device that supports the clearing of the sieve-throughs toward a slot opening provided at the edge of the sieve frame.
The advantage of this known sieve cleaner is that it allows a small overall height of the sieve frame, and that it can easily reach into the corners of the sieve frame with its cantilever arms so that the sieve covering is thoroughly cleaned, including in the corner zones.
When the sieve cleaner bumps against the edge of the sieve frame, the free ends of two arms are in contact with the edge of the sieve frame while the third arm points to the center of the sieve. This results in the fact that cleaning devices treat the central area of the sieve statistically more often than the peripheral areas. This can cause an uneven cleaning effect and lead to an increased wear of the sieve covering in the center of the sieve.
The problem to be solved by the invention is to provide a sieve frame and a sieve cleaner that allow an intensive as well as gentle cleaning of the sieve covering.
