Shaking device for regeneration of filters
Publication Date: 2005-Dec-14
The IP.com Prior Art Database
A project called "filter shaking" has been started to investigate the mechanisms to release dust from a dust filter used in a bag-less vacuum cleaner. Normally these dust filters are pleated to increase the effective surface of filter. In figure 1 some typical dust filters are given.
Figure 1: Typical dust filters
Known methods to release dust from a filter are:
- Rattling, hand operated - Shaking, whole filter inclusive the housing - Blowing, reverse blowing - Washing
This invention uses high vibration levels, generated in the pleats of the filter, to release the dust.
Problems or disadvantages
To release the dust from a filter by shaking the filter, high acceleration level are needed. In previous tests an acceleration level of approximately 4000 m/s2 is determined at with dust started to get loose from the filter. In a domestic appliance it is very hard to realise these high vibration levels without using large shaking devices. The invention however overcome this problem by making use of resonance of the filter pleats to magnify the vibration, and generating force at the pleat
The essential feature(s)
The invention is based on two principles:
1) Resonance of the filter pleats. This has the advantage that the input vibration energy will be magnified in the pleat. The magnification of the input vibration level is depending on the following items: - The transfer of the input vibration towards the pleats
- The damping of the filter material - The amount of non-linearity of the filter material - The mode shape of the excited natural frequency
In case of the filters used in the prototype a magnification of 40 - 60 times the input signal is established. Figure 2 shows a filter sample used for dynamic testing.
Figure 2: filter sample used for dynamic tests
2) Excitation forces generated on one or more pleats of the filter, in this case Lorenz forces are used. Leading an AC current through one or more copper wires in a magnetic field generates these forces, as illustrated in figure 3. The copper wires are attached to the pleats with glue or tape. A horseshoe magnet is used to generate the magnetic field.
Figure 3: Filter sample with wires (red) attached to the pleats.
The amplitude of these forces is depending on the amplitude of the current through the wires, the intensi...