Suction device and method for its operation

17:

• The suction device as recited in claim 16 wherein the first duct is disposed between the motor and the filter, wherein the first duct is formed as a suction duct and runs at least in portions through a piston chamber of the suction device.

18:

• The suction device as recited in claim 17 further comprising a second duct formed as a bypass duct, the second duct being specified to bypass the piston or the piston chamber.

19:

• The suction device as recited in claim 17 wherein the suction operation is maintained by the second duct during filter cleaning.

20:

• The suction device as recited in claim 18 wherein a size of a cross-sectional area of the second duct is in a range of 1-25% of a cross-sectional area of a motor inlet.

21:

• The suction device as recited in claim 18 wherein a size of a cross-sectional area of the second duct is in a range 2-15% of a cross-sectional area of a motor inlet.

22:

• The suction device as recited in claim 18 wherein a size of a cross-sectional area of the second duct is in a range of 3-10% of a cross-sectional area of a motor inlet.

23:

• The suction device as recited in claim 20 wherein the motor inlet delimits the first duct on a turbine side.

24:

• The suction device as recited in claim 16 wherein at least one contact face delimiting movement of the piston from the suction operation position to the filter cleaning position is provided in the piston chamber.

25:

• The suction device as recited in claim 24 wherein the piston chamber has a compression zone extending between the at least one contact face and a motor opening of the piston chamber.

26:

• The suction device as recited in claim 25 wherein a height of the compression zone is less than 1/1500 mm multiplied by a cross-sectional area of the piston in mm2.

27:

• The suction device as recited in claim 16 wherein a length of movement of the piston is greater than or equal to a sum of the height of the compression zone and a diameter of the motor opening.

28:

• The suction device as recited in claim 16 further comprising an intermediate portion disposed between the motor and the piston chamber, the intermediate portion forming a sub-portion of the first duct.

29:

• A method for operating a suction device as recited in claim 16, the method comprising the following steps:
• a) providing the suction device and operating the suction device in a suction operation;
• b) carrying out a filter cleaning procedure by moving a piston from a suction operation position to a filter cleaning position, by this movement closing a first duct so that air between the piston and the filter is compressed in such a way that a surge of compressed air is forced through the filter and the filter is cleaned in this way.

30:

• The method as recited in claim 29 wherein in the suction operation a larger proportion of a suction flow flows through the first duct and a smaller proportion of the suction flow flows through a second duct.

31:

• The method as claimed in claim 30 wherein the suction operation is maintained by the second duct during the filter cleaning procedure.

32:

• The method as recited in claim 30 wherein the piston is returned pneumatically or mechanically to an initial position.