Vacuum cleaning device

1 . A vacuum cleaning device comprising:

a housing having a dirty air inlet and a clean air outlet and an airflow path between the dirty air inlet and the clean air outlet;

a dust container mounted to the housing, wherein the airflow path goes through the dust container;

a motor fan assembly mounted in the housing configured to create a negative pressure airflow along the airflow path in a suction mode and a positive pressure airflow along the airflow path in a blow mode; and

a filter assembly mounted to the housing in the airflow path between the dust container and the motor-fan assembly, the filter assembly having a frame, a coarse filter element mounted to the frame and configured to stop relatively large dirt particles entrained in the negative pressure airflow during the suction mode, a fine filter element configured to stop relatively fine dirt particles entrained in the negative pressure airflow, and an airflow bypass directly attached to the frame and operated during the blow mode to enable the positive pressure airflow to flow through the airflow bypass and bypass the coarse filter element, wherein the relatively large dirt particles are larger than the fine dirt particles, and

wherein, during the blow mode, the positive pressure airflow flows from the motor fan assembly, through the fine filter element, then through the airflow bypass, into the dust container, and out of the dirty air inlet, causing the fine dirt particles that are in a space between the fine filter element and the coarse filter element to bypass the coarse filter element and flow through the airflow bypass into the dust container and out of the dirty air inlet.

2 . The vacuum cleaning device according to claim 1 , wherein the airflow bypass is a one-way valve configured to allow the positive pressure airflow to flow through the airflow bypass during the blow mode and configured to prevent the negative pressure airflow from flowing through the airflow bypass during the suction mode.

3 . The vacuum cleaning device according to claim 1 , wherein the frame includes an opening, and wherein the airflow bypass comprises a door directly attached to the opening of the frame and configured to be open during the blow mode to allow the positive pressure airflow to flow through the opening of the frame.

4 . The vacuum cleaning device according to claim 3 , wherein the door is configured to be closed during the suction mode to prevent the negative pressure airflow from flowing through the opening of the frame.

5 . The vacuum cleaning device according to claim 1 , wherein the airflow bypass comprises a door moveable between an open position during the blow mode and a closed position during the suction mode.

6 . The vacuum cleaning device according to claim 5 , wherein the door is hinged to the frame via a hinge mechanism along an edge of the door.

7 . The vacuum cleaning device according to claim 5 , wherein the door is placed on a front surface of the frame that faces the dust container and the dirty air inlet.

8 . The vacuum cleaning device according to claim 5 , wherein the door is configured to be biased to the closed position under the force of gravity when the vacuum cleaning device is in an upright position.

9 . The vacuum cleaning device according to claim 5 , wherein the door is spring biased to the closed position.

10 . The vacuum cleaning device according to claim 5 , wherein the door is configured to seal against a lip on the frame in the closed position.

11 . The vacuum cleaning device according to claim 1 , wherein the fine filter element is a pleated fabric filter.

12 . The vacuum cleaning device according to claim 1 , wherein the coarse filter element comprises a plastic sheath having a plurality of holes or perforations to stop the large dirt particles entrained in the negative pressure airflow from passing through and allow the fine dirt particles entrained in the negative pressure airflow to pass through during the suction mode.