Dust collector

1. A dust collector comprising:

a tank including a suction opening;

a main body fixed to an upper portion of the tank;

a suction fan disposed at the main body, the suction fan being rotated by a motor;

a flexible pre-filter housed in the tank at a lower side of the main body, the pre-filter being positioned at an upstream side of external air suctioned from the suction opening;

a main filter positioned at a downstream side of the pre-filter;

a damper disposed between the pre-filter and the main filter, wherein the damper contracts due to contraction of the pre-filter when the external air is suctioned from the suction opening; and

a damper restricting unit that restricts at least a partial close contact of the damper with the main filter when the damper elastically deforms, wherein

the main filter has an overall plate shape that is disposed laterally,

the damper restricting unit is disposed on a holder, the holder supporting the main filter,

the damper restricting unit is a tubular filter holder, the tubular filter holder being formed on the holder to hold the main filter, the tubular filter holder projecting downward below a lower filter surface of the main filter, and

the damper restricting unit further includes a plurality of restricting bosses, the plurality of restricting bosses projecting downward below a lower filter surface of the main filter from a lower surface of the holder at positions surrounding the main filter.

2. The dust collector according to claim 1 , wherein

the main filter is held by the holder which is supported inside the tank such that the entire main filter has a plate shape in a state of being folded multiple times in a predetermined direction.

3. The dust collector according to claim 1 , wherein

the damper has a plate shape disposed laterally.

4. A dust collector comprising:

a tank including a suction opening;

a main body fixed to an upper portion of the tank;

a suction fan disposed at the main body, the suction fan being rotated by a motor;

a flexible pre-filter housed in the tank at a lower side of the main body, the pre-filter being positioned at an upstream side of external air suctioned from the suction opening;

a main filter positioned at a downstream side of the pre-filter,

a pre-filter restricting unit that restricts a close contact of the pre-filter with the main filter when the external air is suctioned from the suction opening, and

a damper between the pre-filter and the main filter, wherein

the damper contracts due to contraction of the pre-filter,

the main filter has an overall plate shape that is disposed laterally,

the pre-filter restricting unit is disposed on a holder, the holder supporting the main filter,

the pre-filter restricting unit is a plurality of restricting bosses in an array outside a periphery of the main filter, in a plan view facing the lower filter surface, with each of the restricting bosses projecting downward below a lower filter surface of the main filter from a lower surface of the holder.

5. The dust collector according to claim 1 , wherein:

the main filter has a plate shape disposed laterally, and

the pre-filter is made of fiber where pleat portions are formed into a plurality of tiers in a vertical direction on an outer circumference, the respective pleat portions are partially fixed so that the pre-filter is suspended and supported in a state of being folded so that adjacent layers of material extend in the vertical direction.

6. The dust collector according to claim 5 , wherein

the pleat portions are each sewn in the vertical direction at a plurality of positions at a predetermined interval in a circumferential direction.

7. The dust collector according to claim 5 , wherein

the pre-filter is a bag whose opening is fixed to a frame, the frame configured to lock to an opening at a top surface of the tank.

8. The dust collector according to claim 2 , wherein

the main filter is made of a paper.

9. The dust collector according to claim 1 , wherein the damper is made from a compressible material.

10. The dust collector according to claim 1 , wherein the damper is configured to capture dust.

11. The dust collector according to claim 1 , wherein the damper extends continuously across an area corresponding to the lower filter surface.