U.S. patent application number 17/668128 was filed with the patent office on 2022-08-18 for vacuum cleaner and method of controlling a motor for a brush of the vacuum cleaner.
The applicant listed for this patent is TECHTRONIC FLOOR CARE TECHNOLOGY LIMITED. Invention is credited to Fai Zhao Hui Xie.
Application Number | 20220257076 17/668128 |
Document ID | / |
Family ID | |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220257076 |
Kind Code |
A1 |
Xie; Fai Zhao Hui |
August 18, 2022 |
VACUUM CLEANER AND METHOD OF CONTROLLING A MOTOR FOR A BRUSH OF THE
VACUUM CLEANER
Abstract
A vacuum cleaner that includes a surface cleaning head including
a dirty air inlet, a brush supported by the surface cleaning head,
a motor coupled to and operable to cause movement of the brush, a
sensor to sense a voltage associated with a current of the motor,
and a controller configured to control an amount of current
provided to the motor in response to the sensed voltage. The
controller is configured to control a first pulse width modulated
(PWM) duty cycle provided to the motor when the sensed voltage is
less than a reference voltage, control a second PWM duty cycle
provided to the motor when the sensed voltage is greater than the
reference voltage, the second PWM duty cycle being less than the
first PWM duty cycle, and turn off the motor when the sensed
voltage increases to a voltage associated with an overload current
of the motor.
Inventors: |
Xie; Fai Zhao Hui; (Suzhou
City, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TECHTRONIC FLOOR CARE TECHNOLOGY LIMITED |
Tortola |
|
VG |
|
|
Appl. No.: |
17/668128 |
Filed: |
February 9, 2022 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15878501 |
Jan 24, 2018 |
11324372 |
|
|
17668128 |
|
|
|
|
International
Class: |
A47L 9/28 20060101
A47L009/28; A47L 9/04 20060101 A47L009/04; A47L 9/30 20060101
A47L009/30 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2017 |
CN |
201710997069.X |
Claims
1. A vacuum cleaner comprising: a surface cleaning head including a
dirty air inlet; a brush supported by the surface cleaning head; a
motor coupled to and operable to cause movement of the brush; a
sensor to sense a voltage associated with a current of the motor;
and a controller configured to control an amount of current
provided to the motor in response to the sensed voltage, including
the controller configured to: control a first pulse width modulated
(PWM) duty cycle provided to the motor when the sensed voltage is
less than a reference voltage, control a second PWM duty cycle
provided to the motor when the sensed voltage is greater than the
reference voltage, the second PWM duty cycle being less than the
first PWM duty cycle, and turn off the motor when the sensed
voltage increases to a voltage associated with an overload current
of the motor.
2. The vacuum cleaner of claim 1, wherein the controller further
includes a processing unit and non-transitory memory with
instructions executable by the processing unit, the instructions
when executed by the processing unit include the processing unit
determining whether the sensed voltage is less than, greater than,
or equal to the reference voltage, and generating a signal for
controlling the motor.
3. The vacuum cleaner of claim 2, wherein the processing unit
generating the signal includes decreasing the first PWM duty cycle
to the second PWM duty cycle when the sensed voltage is greater
than the reference voltage.
4. The vacuum cleaner of claim 2, wherein the processing unit
generating the signal includes decreasing the first PWM duty cycle
to the second PWM duty cycle when the sensed voltage is equal to
the reference voltage.
5. The vacuum cleaner of claim 2, wherein the processing unit
generating the signal includes increasing the second PWM duty cycle
to the first PWM duty cycle when the sensed voltage is less than
the reference voltage.
6. The vacuum cleaner of claim 1, wherein the first PWM duty cycle
is a maximum duty cycle and the second PWM duty cycle is a minimum
duty cycle, and when the sensed voltage is greater than the
reference voltage, the maximum duty cycle is decremented by a
percentage value until the minimum duty cycle is obtained.
7. The vacuum cleaner of claim 6 further comprising a display
configured to provide a current stall indication to a user
regarding a reduction of the second PWM duty cycle to below the
minimum duty cycle, the current stall indication provided after
sensing a parameter related to the overload current.
8. The vacuum cleaner of claim 7, wherein the current stall
indication includes instructions for the user to open a mechanical
air bleed.
9. The vacuum cleaner of claim 1, wherein the first PWM duty cycle
is a 100 percent duty cycle.
10. The vacuum cleaner of claim 1, wherein the second PWM duty
cycle is a 50 percent duty cycle.
11. A method of controlling a motor for a brush of a vacuum
cleaner, the method comprising: sensing a voltage associated with a
current of the motor; controlling a first pulse width modulated
(PWM) duty cycle provided to the motor when the sensed voltage is
less than a reference voltage, controlling a second PWM duty cycle
provided to the motor when the sensed voltage is greater than the
reference voltage, the second PWM duty cycle being less than the
first PWM duty cycle, and turning off the motor when the sensed
voltage increases to a voltage associated with an overload current
of the motor.
12. The method of claim 11, further comprising: determining, by a
controller including a processing unit and non-transitory memory
with instructions executable by the processing unit, whether the
sensed voltage is less than, greater than, or equal to the
reference voltage; and generating, by the controller, a signal for
controlling the motor.
13. The method of claim 12, wherein generating the signal includes
decreasing, by the controller, the first PWM duty cycle to the
second PWM duty cycle when the sensed voltage is greater than the
reference voltage.
14. The method of claim 12, wherein generating the signal includes
decreasing, by the controller, the first PWM duty cycle to the
second PWM duty cycle when the sensed voltage is equal to the
reference voltage.
15. The method of claim 12, wherein generating the signal includes
increasing, by the controller, the second PWM duty cycle to the
first PWM duty cycle when the sensed voltage is less than the
reference voltage.
16. The method of claim 11, wherein the first PWM duty cycle is a
maximum duty cycle and the second PWM duty cycle is a minimum duty
cycle, and wherein the method further comprises decrementing the
maximum duty cycle by a percentage value until the minimum duty
cycle is obtained when the sensed voltage is greater than the
reference voltage.
17. The method of claim 16, further comprising displaying, on a
display of the vacuum cleaner, a current stall indication to a user
regarding a reduction of the second PWM duty cycle to below the
minimum duty cycle after sensing a parameter related to the
overload current.
18. The method of claim 17, wherein displaying the current stall
indication includes instructing the user to open a mechanical air
bleed.
19. The method of claim 11, wherein the first PWM duty cycle is a
100 percent duty cycle.
20. The method of claim 11, wherein the second PWM duty cycle is a
50 percent duty cycle.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/878,501, filed Jan. 24, 2018, which claims
the benefit of Chinese Patent Application No. 201710997069.XA,
filed Oct. 20, 2017, and the entire contents of each are hereby
incorporated by reference.
BACKGROUND
[0002] The invention relates to a vacuum cleaner including a
surface cleaning head having a brush and motor for operating the
brush.
[0003] Upright vacuum cleaners are typically used to clean floor
surfaces, such as carpeting. Sometimes the carpeting can have a
long pile height or other attribute providing a significant
resistance to the brush of the vacuum cleaner.
SUMMARY
[0004] A first aspect of the disclosure provides a vacuum cleaner
that includes a surface cleaning head including a dirty air inlet,
a brush supported by the surface cleaning head, a motor coupled to
and operable to cause movement of the brush, a sensor to sense a
voltage associated with a current of the motor, and a controller
configured to control an amount of current provided to the motor in
response to the sensed voltage. The controller is configured to
control a first pulse width modulated (PWM) duty cycle provided to
the motor when the sensed voltage is less than a reference voltage,
control a second PWM duty cycle provided to the motor when the
sensed voltage is greater than the reference voltage, the second
PWM duty cycle being less than the first PWM duty cycle, and turn
off the motor when the sensed voltage increases to a voltage
associated with an overload current of the motor.
[0005] Another aspect of the disclosure provides a method of
controlling a motor for a brush of a vacuum cleaner. The method
includes sensing a voltage associated with a current of the motor,
controlling a first pulse width modulated (PWM) duty cycle provided
to the motor when the sensed voltage is less than a reference
voltage, and controlling a second PWM duty cycle provided to the
motor when the sensed voltage is greater than the reference
voltage, the second PWM duty cycle being less than the first PWM
duty cycle. The method further includes turning off the motor when
the sensed voltage increases to a voltage associated with an
overload current of the motor.
[0006] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of a vacuum cleaner according
to an embodiment of the invention.
[0008] FIG. 2 is a sectional view of a portion of the vacuum
cleaner of FIG. 1.
[0009] FIG. 3 is a block diagram of a portion of the control
circuit for the vacuum cleaner of FIG. 1
[0010] FIG. 4 is a block diagram of a portion of the firmware used
to control the brush motor of the control circuit of FIG. 3.
DETAILED DESCRIPTION
[0011] Before any embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways.
[0012] FIG. 1 illustrates an exemplary vacuum cleaner 10. The
vacuum cleaner 10 includes a surface cleaning head 15, a pivot
assembly 20, and a canister assembly 25. The vacuum cleaner 10
further includes an upright handle 30. The vacuum cleaner 10 shown
in FIG. 1 is typically referred to as an upright vacuum cleaner.
However, the invention is not limited to upright vacuum cleaners,
i.e., can be used in other vacuum types for example canister
vacuums, stick vacuums, and robot vacuums, and the arrangement of
the upright vacuum cleaner can vary from the vacuum cleaner 10
shown in FIG. 1.
[0013] In the illustrated embodiment of FIG. 1, the surface
cleaning head 15 is movable along a surface 35 to be cleaned, such
as a carpeted floor. The upright handle 30 allows a user to move
the surface cleaning head 15 along the surface 35. The upright
handle 30 is also movable relative to the surface cleaning head 15
between an upright position (FIG. 1) and an inclined position.
[0014] The surface cleaning head 15 includes a dirty air inlet 40
(shown in FIG. 2). The surface cleaning head further includes a
brushroll (also referred to as a brush) 45 for agitating the
surface 35 being cleaned. The brush 45 is driven by a brush motor
50 (shown in FIG. 3).
[0015] The vacuum cleaner 10 includes other electrical components
besides the brush motor 50 that are part of an appliance control
circuit 55. With reference to FIG. 3, the control circuit 55
further includes an appliance controller 60, a suction motor 65, a
user interface, and sensors.
[0016] The appliance controller 60 includes combinations of
software and hardware that are operable to, among other things,
control the operation of the vacuum 10, receive input from the
sensors, receive input or provide output with the user interface,
and control the motors 50 and 65.
[0017] In one construction, the appliance controller 60 includes a
printed circuit board ("PCB") that is populated with a plurality of
electrical and electronic components that provide, power,
operational control, and protection to the vacuum 10. In some
constructions, the PCB includes, for example, a processing unit 70
(e.g., a microprocessor, a microcontroller, or another suitable
programmable device) and a memory 75. The memory 75 includes, for
example, a read-only memory ("ROM"), a random access memory
("RAM"), an electrically erasable programmable read-only memory
("EEPROM"), a flash memory, or another suitable magnetic, optical,
physical, or electronic memory device. The processing unit 70 is
connected to the memory 75 and executes instructions (e.g.,
software) that is capable of being stored in the RAM (e.g., during
execution), the ROM (e.g., on a generally permanent basis), or
another non-transitory computer readable medium such as another
memory or a disc. Additionally or alternatively, the memory 75 is
included in the processing unit 70 (e.g., as part of a
microcontroller).
[0018] Software included in this implementation of the vacuum
cleaner 10 is stored in the memory 75 of the appliance controller
60. The software includes, for example, firmware, program data, one
or more program modules, and other executable instructions. The
appliance controller 60 is configured to retrieve from memory and
execute, among other things, instructions related to the control
processes and methods described herein.
[0019] The PCB also includes, among other things, a plurality of
additional passive and active components such as resistors,
capacitors, inductors, integrated circuits, and amplifiers. These
components are arranged and connected to provide a plurality of
electrical functions to the PCB including, among other things,
signal conditioning or voltage regulation. For descriptive
purposes, the PCB and the electrical components populated on the
PCB are collectively referred to as the appliance controller 60. It
should also be noted that the current sensor (discussed below), for
example can be mounted on the PCB and also considered part of the
appliance controller 60. However, for ease of description, the
current sensor will be described separately.
[0020] The user interface is included to control the vacuum cleaner
10. The user interface can include a combination of digital and
analog input devices to control the vacuum cleaner 10. For example,
the user interface can include a display 80 and a switch 85, or the
like. The display 80 can be as simple as LEDs indicating operation
of the vacuum cleaner 10, and the switch 85 can be used for
activating/deactivating the vacuum cleaner 10. The display 80 can
be mounted on a PCB with other additional passive and active
components necessary for controlling the display, similar to what
was discussed for the appliance controller 60, or can be mounted on
the PCB for the appliance controller 60.
[0021] The appliance controller 60 operates the brushroll motor 50
and the suction motor 65, the operation of which may be based on a
floor type. For example, the appliance controller 60 may operate
the suction motor 65 at a lower power on a hard floor surface to
conserve energy or a higher power on a hard floor surface to
increase debris pick-up. In some embodiments, the brushroll motor
50 may be operated at a lower power on certain height carpets to
reduce the action of the brushroll 45 to the carpet and the force
applied from the carpet to the brushroll, or carpet load, so that
the vacuum cleaner 10 is less likely to stall, for example.
[0022] The current sensor 90 (also sometimes referred to as the
brushroll sensor) refers to a sensor that senses an electrical
parameter related directly or indirectly to an aspect of carpet
load restricting the brush. An exemplary parameter may be the
amount of current to or through the brushroll motor 50. The
brushroll sensor can be a tachometer for sensing a revolutions per
minute (RPM) value of the brushroll 45, a tachometer for sensing an
RPM value of the brushroll motor 50, an electrical sensor (e.g.,
the current sensor) for sensing an electrical parameter (e.g.,
current or voltage) of the brushroll motor 50, a torque sensor for
sensing a torque parameter of the brushroll motor 50, etc. It is
envisioned that the number of sensors can be greater than the
single sensor shown.
[0023] With reference to the implementation of FIG. 3, the vacuum
cleaner 10 includes a current sensor 90 and an appliance controller
60 in communication with the current sensor 90. The current sensor
90 is configured to sense a parameter indicative of the current
draw of the brushroll motor 50. The appliance controller 60
receives a signal from the current sensor 90 and compares the
signal with a corresponding predetermined threshold. In some
implementations, the appliance controller 60 includes an overload
protection that will stop the brushroll motor 50 and/or vacuum
cleaner operation after sensing a parameter related to an overload
current (e.g., 2.3 amps in one specific example). In order to
preserve the life of the brushroll motor 50 a current stall
indication may be provided to the user before the overload current,
or failure threshold is met. However, a load of this magnitude is
possible during normal use on high pile carpet height, for example.
In order to prevent the current stall from occurring, a mechanical
air bleed may be provided in the suction flow path of the vacuum
cleaner 10 to provide inflow of air to the vacuum through the air
bleed. The user is instructed to open the mechanical bleed if they
are experiencing a brushroll stall event during normal use because
the inflow of air to the vacuum reduces the amount of suction at
the nozzle, reducing the nozzle engagement to the carpet caused by
suction. Opening of the mechanical bleed reduces both the carpet
load on the brushroll 45 and also the cleaning efficiency of the
vacuum cleaner 10 itself.
[0024] An alternative, or even additive, approach is to monitor the
current being fed through the brushroll motor 50 and to
automatically adjust via pulse width modulation (PWM) the voltage
input to the brushroll motor 50. As a result of decreasing the
voltage to the brushroll motor 50, the current consumption of the
brushroll motor 50 will also decrease as well as the speed of the
brushroll 45 itself. As a result, the brushroll motor 50 can be
automatically protected without user intervention.
[0025] In FIG. 3, a control signal 95 is a PWM signal from the
controller 60. When the PWM signal is high, current flows through
the switch 100 to the brushroll motor 50. When the PWM signal is
low, current is restricted by the switch 100. The actual average
motor input voltage can be varied by adjusting the PWM signal from
a maximum to a minimum duty cycle.
[0026] The current through the brushroll 50 is monitored with the
current sensor 90. In one embodiment, a voltage indicative of the
brushroll current is acquired from a secondary side of a
transformer in a current path from the switch 85 to the brushroll
motor 50. In an alternative embodiment, a voltage indicative of the
brushroll current is acquired from a resistor network in a current
path between the switch 85 and the brushroll motor 50. Firmware of
the appliance controller 60 uses information gained from the
current sensor signal to make adjustments to the control signal 95
to decrease the voltage at the motor as a result of increased
current due to loading as a result of high pile carpet.
[0027] An exemplary firmware logic is shown in FIG. 4. A reference
voltage 105 is set in the firmware. The reference voltage is less
than the voltage associated with the overload current and selected
to extend the brushroll motor run time in desired user conditions.
The reference voltage may be a voltage providing a corresponding
current that is a function of the overload current, such as 80% or
85% or 90% or other function of the overload current of the
brushroll motor. Alternatively or additionally, the reference
voltage is empirically determined to extend the brushroll motor run
time a desired amount in the user condition. In one specific
example, a reference voltage associated with 2.1 Amps is the
maximum voltage that an implementation allows the PWM signal to
operate with 100 percent duty.
[0028] The vacuum cleaner 10 is turned on by the user with switch
85 and information is acquired via the current sensor 90. The
firmware determines a difference between the current signal and the
set point reference (at 110). The firmware uses a filter, such as a
proportional, integral, and derivative (PID) filter 115, to filter
the peaks and valleys out of the signal. If the current measurement
is smaller than the reference voltage (at 120), the PWM duty cycle
is increased to a PWM value. In some implementations, the PWM value
is set to maximum voltage (e.g., 100 percent duty cycle). In other
implementations, the PWM value is incremented by a value amount
(e.g., 10 percent) until the maximum duty cycle is obtained. The
PWM duty cycle typically remains at the maximum duty cycle until
the voltage at the brushroll motor is equal to or larger than the
reference voltage.
[0029] If the voltage associated with the brushroll current
measurement is larger than the reference voltage, the PWM value is
decreased to extend the brushroll motor run time before reaching
the overload current. In some implementations, the PWM value is
decremented by a value amount (e.g., 10 percent) until a minimum
duty cycle is obtained. For example, the minimum duty cycle value
may be 50 percent. In an alternative implementation, the PWM value
is decremented as a function of the reference voltage until the
minimum duty cycle is obtained. In yet another implementation, the
duty cycle is set to a first PWM duty cycle when the voltage is
smaller than the reference voltage and a second, non-zero, PWM duty
cycle when the voltage is larger than the reference voltage. For
example, the duty cycle may be 100% when the voltage associated
with the brushroll current measurement is below the reference
voltage and the duty cycle may be 50% when the voltage is above the
reference voltage. If the firmware wants to reduce the PWM value to
be less than the minimum duty cycle value, then a current stall
indication may be displayed to the user. The brushroll motor
continues to operate at the reduced PWM duty cycle value until the
current sensor signal of the brushroll motor either increases to
the predetermined voltage associated with the overload current or
decreases to below the reference voltage. When the brushroll motor
current reaches the overload current, the controller turns off the
brushroll motor. When the voltage of the current sensor drops below
the reference voltage, the controller increases the PWM duty cycle
value. In one embodiment, when the measured voltage drops below the
reference voltage, the controller determines whether the PWM duty
cycle value is less than an upper limit. The upper duty cycle limit
may be 100%, or may be a lower limit such as 95% or 90% or any
other desired predetermined limit. If the PWM duty cycle value is
less than an upper limit and the measured voltage is less than the
reference voltage, the controller increases the PWM duty cycle
value. The controller may increase the PWM duty cycle to the upper
limit or may increase the PWM duty cycle a predetermined
amount.
[0030] Accordingly, the invention provides a new and useful vacuum
cleaner and method of controlling a motor for a brush of the vacuum
cleaner. Various features and advantages of the invention are set
forth in the following claims.
* * * * *