摘要 |
A filter assembly including a continuous resilient cylindrical helical filter coil having flat top and bottom surfaces with each coil including a regular sinusoidal shape having multiple peaks and troughs with the flat top and bottom surfaces of adjacent coils in contact and a drive engaging the helical coil moving adjacent coils relative to each other to modify the volume of the loop-shaped filter pores and control the pore size. In one embodiment, the drive rotates a coil relative to the remaining coils to bring the sinusoidal waves of adjacent coils into and out of registry to decrease or increase the size of the filter pores. In another embodiment, the drive compresses the filter coil to change the size of the filter pores.
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