Vacuum cleaner

Abstract

The invention relates to a vacuum cleaner with a dirt collection tank which has a suction inlet and is in flow connection with at least one suction unit via at least one filter and at least one extraction line, and with at least one external air inlet which opens into the extraction line downstream of the at least one filter and can be closed by means of at least one closing valve, wherein the at least one closing valve has a valve member which can be moved back and forth between a closing position and an open position, wherein it is acted upon permanently by a closing spring with a closing force and in the closing position, in addition, by a magnetic holding device with a magnetic holding force. In order to develop the vacuum cleaner further in such a manner that it makes a particularly effective cleaning of the at least one filter possible, it is suggested in accordance with the invention that the magnetic holding device comprise an electromagnet with a magnetic core and a coil which can be acted upon with current for the purpose of closing the closing valve, wherein at least one electrical component, which takes up at least some of the energy stored in the coil when the current acting on the coil ceases, is connected in parallel to the coil.

1 . Vacuum cleaner with a dirt collection tank having a suction inlet and being in flow connection with at least one suction unit via at least one filter and at least one extraction line, and with at least one external air inlet opening into the extraction line downstream of the at least one filter, said external air inlet being closable by means of at least one closing valve, wherein the at least one closing valve has a valve member movable back and forth between a closing position, said valve member abutting on a valve seat in said closing position, and an open position, said valve member being spaced from the valve seat in said open position, wherein said valve member is acted upon permanently by a closing spring with a closing force and in the closing position, in addition, by a magnetic holding device with a magnetic holding force, wherein the magnetic holding device comprises an electromagnet with a magnetic core and a coil adapted to be acted upon with current for the purpose of closing the closing valve, wherein at least one electrical component is connected in parallel to the coil, said component taking up at least some of the energy stored in the coil when the current acting on the coil ceases. 
   
   
       2 . Vacuum cleaner as defined in  claim 1 , wherein a freewheeling diode and at least one electrical component taking up energy and being connected in series thereto are connected in parallel to the coil. 
   
   
       3 . Vacuum cleaner as defined in  claim 1 , wherein a freewheeling diode and a Zener diode connected in-series thereto are connected in parallel to the coil, said Zener diode being polarized in an opposite direction to the freewheeling diode. 
   
   
       4 . Vacuum cleaner as defined in  claim 3 , wherein the Zener diode has a breakdown voltage of approximately 50 V. 
   
   
       5 . Vacuum cleaner as defined in  claim 1 , wherein the coil and the at least one component connected in parallel to the coil are adapted to be connected to a source of AC voltage via an electrical switching unit and a rectifier unit. 
   
   
       6 . Vacuum cleaner as defined in  claim 1 , wherein the magnetic core is connected via a potential equalization line to a reference potential predetermined externally. 
   
   
       7 . Vacuum cleaner as defined in  claim 6 , wherein the potential equalization line connects the magnetic core to a mains voltage supply connection, wherein at least one ohmic resistor is connected into the potential equalization line. 
   
   
       8 . Vacuum cleaner as defined in  claim 7 , wherein two ohmic resistors with different resistance values are connected into the potential equalization line in series to one another. 
   
   
       9 . Vacuum cleaner as defined in  claim 1 , wherein the electromagnet is arranged on a valve holding device forming the valve seat and wherein the valve member has a magnetizable element associated with the electromagnet, said element forming a magnetic circuit with the electromagnet in the closing position of the valve member. 
   
   
       10 . Vacuum cleaner as defined in  claim 9 , wherein in the closing position of the valve member the magnetizable element abuts on the end side of the electromagnet, thereby forming a gap of air. 
   
   
       11 . Vacuum cleaner as defined in  claim 10 , wherein the gap of air is narrower than 1 mm. 
   
   
       12 . Vacuum cleaner as defined in  claim 1 , wherein the supply of current to the coil is adapted to be interrupted several times one after the other for a period of time of at the most 0.2 seconds at time intervals of less than one second. 
   
   
       13 . Vacuum cleaner as defined in  claim 1 , wherein the supply of current to the coil is adapted to be interrupted several times one after the other for less than 0.2 seconds at time intervals of 10 to 30 seconds. 
   
   
       14 . Vacuum cleaner as defined in  claim 1 , wherein a flexible stop element is associated with the valve member, said stop element acting on the valve member with a repulsion force in a position spaced from the valve seat. 
   
   
       15 . Vacuum cleaner as defined in  claim 14 , wherein the flexible stop element is designed as a stop spring. 
   
   
       16 . Vacuum cleaner as defined in  claim 15 , wherein the spring constant of the stop spring is greater than the spring constant of the closing spring. 
   
   
       17 . Vacuum cleaner as defined in  claim 15 , wherein the closing spring and the stop spring are designed as helical springs with different diameters, wherein one of the two helical springs surrounds the other helical spring in circumferential direction. 
   
   
       18 . Vacuum cleaner as defined in  claim 1 , wherein the vacuum cleaner has a single filter. 
   
   
       19 . Vacuum cleaner as defined in  claim 18 , wherein the filter is adapted to be acted upon with external air over its entire surface area as a result of the closing valve being opened. 
   
   
       20 . Vacuum cleaner as defined in  claim 1 , wherein the valve member is movable continuously back into its closing position via its open position, proceeding from its closing position. 
   
   
       21 . Vacuum cleaner as defined in  claim 1 , wherein the at least one filter is adapted to be acted upon with external air by means of the at least one closing valve whilst a vacuum is maintained in the opening area of a suction hose opening into the suction inlet.