Surface cleaning appliance

• US 9,801,516 B2
• Filed: 06/13/2014
• Issued: 10/31/2017
• Est. Priority Date: 06/13/2013
• Status: Active Grant

• Current Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Original Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Inventors: Zheng, Libo, Zhou, Yongji, Chisholm, James Douglas, Hawker, David John
• Primary Examiner(s): SCRUGGS, ROBERT J
• Application Number:
  US14/304,619
• Publication Number:
  US 20140366286A1
• Time in Patent Office: 1,236 Days
• CPC Class Codes: A47L 11/4008 Arrangements of switches, indicators or the like
• CPC Class Codes: A47L 11/4011 Regulation of the cleaning machine by electric means; Control systems and remote control systems therefor
• CPC Class Codes: A47L 11/4069 Driving or transmission means for the cleaning tools
• CPC Class Codes: A47L 9/2831 Motor parameters, e.g. motor load or speed
• CPC Class Codes: A47L 9/2847 Surface treating elements
• CPC Class Codes: A47L 9/2857 User input or output elements for control, e.g. buttons, switches or displays

Abstract

A surface cleaning appliance having a cleaner head that includes an agitator and a motor for driving the agitator. The appliance includes a switch coupling the motor to a supply voltage, a voltage sensor for measuring the magnitude of the supply voltage, a current sensor for measuring the magnitude of current through the motor, and a controller configured to output a PWM signal for controlling the switch. The controller then adjusts the duty cycle of the PWM signal in response to changes in the supply voltage and in response to changes in the current through the motor.

Claims

1. A surface cleaning appliance comprising:

a cleaner head comprising an agitator and a motor for driving the agitator;

a switch coupling the motor to a supply voltage;

a voltage sensor for measuring the magnitude of the supply voltage;

a current sensor for measuring the magnitude of current through the motor; and

a controller configured to output a PWM signal for controlling the switch,

wherein the controller adjusts the duty cycle of the PWM signal in response to changes in the supply voltage and in response to changes in the current through the motor.

2. The appliance of claim 1, wherein the controller adjusts the duty cycle so as to maintain a constant input voltage to the motor.

3. The appliance of claim 1, wherein the controller increases the duty cycle in response to a decrease in the supply voltage and in response to an increase in the motor current.

4. The appliance of claim 1, wherein in response to a given change in the motor current the controller adjusts the duty cycle by a larger amount when the supply voltage is lower.

5. The appliance of claim 1, wherein the controller stores a voltage lookup table and a current lookup table, the controller indexes the voltage lookup table using the measured supply voltage to select a first value, the controller indexes the current lookup table using the measured motor current to select a second value, and the duty cycle is defined by the sum of the first value and the second value.

6. The appliance of claim 5, wherein the controller indexes the current lookup table using the measured motor current and the measured supply voltage to select the second value.

7. The appliance of claim 1, wherein the controller employs a predefined duty cycle when the motor is stationary, the controller determines a target duty cycle using the measured supply voltage and the measured motor current, and the controller periodically increases the duty cycle by a fixed amount until the duty cycle is equal to or greater than the target duty cycle.

8. The appliance of claim 1, wherein the appliance comprises a battery pack that provides the supply voltage.

9. A surface cleaning appliance comprising:

a cleaner head comprising an agitator and a motor for driving the agitator;

a switch coupling the motor to a supply voltage;

a voltage sensor for measuring the magnitude of the supply voltage;

a current sensor for measuring the magnitude of current through the motor; and

a controller configured to output a PWM signal for controlling the switch,

wherein the controller increases the duty cycle of the PWM signal in response to a decrease in the supply voltage and in response to an increase in the motor current.

10. The appliance of claim 9, wherein in response to a given change in the motor current the controller adjusts the duty cycle by a larger amount when the supply voltage is lower.

11. A surface cleaning appliance comprising:

a cleaner head comprising an agitator and a motor for driving the agitator;

a switch coupling the motor to a supply voltage;

a voltage sensor for measuring the magnitude of the supply voltage;

a current sensor for measuring the magnitude of current through the motor; and

a controller configured to output a PWM signal for controlling the switch,

wherein the controller increases the duty cycle of the PWM signal in response to a decrease in the supply voltage and in response to an increase in the motor current so as to maintain a constant input voltage to the motor.

12. The appliance of claim 11, wherein in response to a given change in the motor current the controller adjusts the duty cycle by a larger amount when the supply voltage is lower.