Air cleaner

DETAILED DESCRIPTION According to the present invention there is provided an air cleaner for removing particles contained in an air stream directed through the air cleaner, comprising a charging section for charging particles in the air stream and a precipitation section for capture of charged particles, wherein the charging section comprises a first and a second array of substantially parallel wires, each array being disposed in a respective plane substantially perpendicular to the direction of air flow, the wires of the first and second arrays being held at a first potential, and a third array of substantially parallel wires sandwiched between the first and second arrays, the wires of the third array being held at a second potential.
The design of charging section according to the invention requires three wired frames which provides a simple mechanical construction.
Preferably the wires of the first and second arrays are earthed, and the wires of the third array are held at a corona discharge voltage.
The design of the charging section is independent of the precipitation section design, so that both sections of the air cleaner may be optimised independently.
Furthermore, the spacing between earthed wires and the spacing between corona wires can be selected independently to obtain the most favourable corona discharge conditions.
During operation of the filter, the arrays of earth wires in particular become gradually fouled with dust particles.
Since the first and second arrays of earth wires are arranged at the periphery of the charging section, surrounding the corona discharge wires, they can easily be manually cleaned.
Furthermore, the dust particles travelling through the filter will be charged before they reach the central array of corona discharge wires, and will therefore be repelled from the corona discharge wires.
The corona wires are therefore less susceptible to fouling.
The earth wires surrounding the corona wires also act as a partial Faraday cage, to minimise any influence of stray environmental electric fields on the corona discharge conditions