Vacuum cleaner

Abstract

A vacuum cleaner comprises a cleaner head defining a suction chamber and having an agitator arranged to be rotated by an agitator motor, a dirt separator, a vacuum motor arranged to draw air into the suction chamber and then into the dirt separator, and a controller. The controller is configured to monitor the electrical load of the agitator motor, compare the magnitude of the electrical load to a threshold, and selectively adjust the electrical power delivered to the vacuum motor. The controller is configured either to increase the electrical power delivered to the vacuum motor to a predetermined upper power level if the electrical load is greater than the threshold, or to decrease the electrical power delivered to the vacuum motor to a predetermined lower power level if the electrical load is smaller than the threshold.

1 . A vacuum cleaner comprising:
 a cleaner head defining a suction chamber and having an agitator arranged to be rotated by an agitator motor;   a dirt separator;   a vacuum motor arranged to draw air into the suction chamber and then into the dirt separator; and   a controller configured to:
 monitor an electrical load of the agitator motor; 
 compare the magnitude of the electrical load to a spike threshold; and 
 provide a rapid step decrease in electrical power delivered to the vacuum motor in response to determining that the electrical load is larger than the spike threshold, initiate a time delay, and following expiration of the time delay, compare the magnitude of the electrical load to the spike threshold to determine whether the electrical load remains larger than the spike threshold. 
   
     
     
         2 . The vacuum cleaner according to  claim 1 , wherein the controller is further configured to:
 compare the magnitude of the electrical load to a first threshold, and selectively adjust the electrical power delivered to the vacuum motor by at least one of increasing the electrical power delivered to the vacuum motor to a predetermined upper power level when the electrical load is greater than the first threshold, or decreasing the electrical power delivered to the vacuum motor to a predetermined lower power level when the electrical load is smaller than the first threshold,   wherein the spike threshold is higher than the first threshold.   
     
     
         3 . The vacuum cleaner according to  claim 2 , wherein the first threshold is a threshold range having an upper limit and a lower limit, and the controller is configured both to increase the power delivered to the vacuum motor to the upper power level when the electrical load is greater than the upper limit of the threshold range, and to decrease the power delivered to the vacuum motor to the lower power level when the electrical load is smaller than the lower limit of the threshold range. 
     
     
         4 . The vacuum cleaner according to  claim 3 , wherein the controller is configured to continue monitoring the electrical load of the agitator after making an adjustment to the power delivered to the vacuum motor, and to make a further adjustment upon detecting that the electrical load of the agitator motor has crossed over one of the upper or lower limit of the threshold range. 
     
     
         5 . The vacuum cleaner according to  claim 2 , wherein the controller can be configured to supply to the vacuum motor no other power level except the upper power level and the lower power level. 
     
     
         6 . The vacuum cleaner according to  claim 2 , wherein the controller is configured to deliver a predetermined initial power level, which does not correspond to the upper power level or the lower power level, to the vacuum motor when the vacuum cleaner is turned off and then on again. 
     
     
         7 . The vacuum cleaner according to  claim 2 , wherein the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level gradually. 
     
     
         8 . The vacuum cleaner according to  claim 7 , wherein the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level over a time of at least 0.5 seconds. 
     
     
         9 . The vacuum cleaner according to  claim 7 , wherein the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level over a time of no more than 6 seconds. 
     
     
         10 . The vacuum cleaner according to  claim 2 , wherein the first threshold is a discrete value. 
     
     
         11 . The vacuum cleaner according to  claim 2 , wherein the controller is configured to adjust the power delivered to the vacuum motor in said manner when the controller is in a first mode, and wherein the controller has a second mode. 
     
     
         12 . The vacuum cleaner according to  claim 11 , wherein the controller is configured to supply a single predetermined power level to the vacuum motor when the controller is in the second mode. 
     
     
         13 . The vacuum cleaner according to  claim 1 , wherein the controller is configured to monitor the agitator motor electrical load in terms of current draw of the electrical motor, and compare the current draw detected to a current spike threshold. 
     
     
         14 . The vacuum cleaner according to  claim 1 , wherein the controller is configured to retain a record of the power level that was being delivered to the vacuum motor when the vacuum cleaner was last turned off, and is configured to resume delivery of that power level to the vacuum motor when the vacuum cleaner is next turned on. 
     
     
         15 . A method of controlling power to a vacuum cleaner, comprising:
 monitoring an electrical load of an agitator motor;   comparing a magnitude of the electrical load to a spike threshold; and   providing a rapid step decrease in electrical power delivered to a vacuum motor in response to determining that the electrical load is larger than the spike threshold, initiating a time delay, and following expiration of the time delay, comparing the magnitude of the electrical load to the spike threshold to determine whether the electrical load remains larger than the spike threshold.   
     
     
         16 . The method of  claim 15 , further comprising comparing the magnitude of the electrical load to a first threshold, and selectively adjusting the electrical power delivered to the vacuum motor by at least one of increasing the electrical power delivered to the vacuum motor to a predetermined upper power level when the electrical load is greater than the first threshold, or decreasing the electrical power delivered to the vacuum motor to a predetermined lower power level when the electrical load is smaller than the first threshold,
 wherein the spike threshold is higher than the first threshold.   
     
     
         17 . The method of  claim 16 , wherein the first threshold is a threshold range having an upper limit and a lower limit, and wherein the power delivered to the vacuum motor is increased to the upper power level when the electrical load is greater than the upper limit of the threshold range, and the power delivered to the vacuum motor is decreased to the lower power level when the electrical load is smaller than the lower limit of the threshold range. 
     
     
         18 . The method of  claim 16 , wherein the power delivered to the vacuum motor is adjusted to the upper or lower power level gradually. 
     
     
         19 . The method of  claim 18 , wherein the power delivered to the vacuum motor is adjusted to the upper or lower power level over a time of at least 0.5 seconds. 
     
     
         20 . The method of  claim 15 , further comprising retaining a record of the power level that was being delivered to the vacuum motor when the vacuum cleaner was last turned off, and resuming delivery of that power level to the vacuum motor when the vacuum cleaner is next turned on.