WO2004032696A2

WO2004032696A2 - Method and apparatus to control the power delivery to an appliance

Info

Publication number: WO2004032696A2
Application number: PCT/CA2003/001511
Authority: WO
Inventors: Wayne E. Conrad
Original assignee: Polar Light Ltd
Current assignee: Polar Light Ltd
Priority date: 2002-10-10
Filing date: 2003-10-09
Publication date: 2004-04-22
Anticipated expiration: 2005-04-10
Also published as: WO2004032696A3

Abstract

An appliance comprises an electrically operated member; and, a power control system electrically connectable to a power source and the electrically operated member, the power control system reducing the voltage delivered to the electrically operated member to an essentially constant level less than the voltage delivered by the power source when the appliance is actuated. Methods of using the power control system are also provided.

Description

Title: Method and Apparatus to Control the Power Delivery to an

Appliance

FIELD OF THE INVENTION

[0001] This invention relates to a power control system for an appliance and, in one embodiment, a battery-operated appliance. In one particular embodiment this invention relates to vacuum cleaner and a vacuum cleaner having such a power control system.

BACKGROUND OF THE INVENTION

[0002] Electrically operated appliances have become widespread since the advent of electricity. From power tools, such as hand drills, sanders and jig saws, to cleaning tools, such as vacuum cleaners and electric toothbrushes, to electronic devices, such as computers and PDAs, power tools are commonplace in the home and office. More recently, battery operated versions of many of these appliances have bee developed.

[0003] For example, historically, vacuum cleaners have been designed to operate using electricity that is obtained from an electrical wall outlet. When the vacuum cleaner is operated, the electricity is provided to a suction motor to produce suction. More recently, battery operated vacuum cleaners have been developed. Typically, these products have been designed to have a single level of suction provided by the suction motor

[0004] More recently, developments have been directed towards providing variable speed control for vacuum motors. U.S. Patent No. 6,008,608, which issued to Holstein et al., discloses a switch and speed control assembly for an electronically controlled vacuum cleaner motor. Holstein et al. '608 provides a control member coupled to a voltage varying device that regulates the amount of power supplied to the vacuum cleaner motor control circuit. The control member includes a thumb wheel, which is operated by the user to manually adjust the voltage varying device to selectively vary the speed of the vacuum cleaner motor. Holstein et al. '608 teaches that a spring may apply a counterforce to the control member to return the motor speed to a normal operating condition after momentarily engaging a "high on" mode. Thus, in Holstein et al. '608, the user must manually operate the control member.

[0005] In U.S. Patent No. 4,969,229, which issued to Svanberg et al., a battery operated surface treatment apparatus having a booster function is disclosed in which a separate battery is connected in series with the batteries in the main power supply unit in order to temporarily boost the power. A knob is manually operated to activate the booster function. A timing control is optionally provided to limit the period of operation of the booster function in order to prevent overheating. Svanberg et al. '229 indicates at column 1 , lines 27-31 , that the invention is directed to vacuum cleaners not provided with any electronic speed control.

[0006] In U.S. Patent No. 4,811 ,450, which issued to Readings, a vacuum cleaner having an auxiliary cleaning means is disclosed. The auxiliary cleaning means of Readings '450 includes a flanged portion, which is used to divert the suction force in a main suction air channel into an auxiliary cleaning hose. According to Readings '450, during auxiliary cleaning, an increased suction force may be created in the auxiliary hose by closing off the air flow in the main suction air channel, thereby relieving part of the load on the common suction motor. Readings '450 explains that such relief results in increased rotational speed of the motor, which in turn correspondingly increases the suction air flow in the auxiliary hose. However, Readings '450 makes it clear, at column 1 , lines 54-60, that in the auxiliary mode, the increase in the operational speed of the suction motor is obtained without requiring any electronic motor control or regulation.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to improving the performance and/or efficiency of appliances and preferably battery- operated appliances and, in a particularly preferred embodiment, vacuum cleaners. For example, the instant invention may be used to maintain the efficiency of a battery operated vacuum cleaner and, more preferably, a battery operated vacuum cleaner, which has various operating modes. The invention may be applied to any known design for battery operated vacuum cleaners. Preferably, the vacuum cleaner has a suction motor and fan assembly for creating suction and a rotating brush, which is driven by a brush motor.

[0008] Typically, the power (current or voltage) delivered by batteries will decrease over the cycle of a battery (i.e. as the charge stored in a battery is expended, then the current or voltage provided by the battery will drop). At some point, the charge stored in a battery will be expended and the battery will no longer supply power until the battery is recharged. While the rate of power drop off varies between different types of batteries (NiCad compared to NiMH), the same phenomenon is encountered to some degree. Therefore, as the charge of a battery is used, the suction provided by the suction motor and the speed of rotation of the brush will decrease. Accordingly, the cleaning efficiency of the vacuum cleaner will decrease.

[0009] In accordance with the instant invention a power control system is provided for a vacuum cleaner wherein the level of power delivered to the suction motor of the vacuum cleaner will not decrease, or at least essentially not decrease, over a cycle of the battery (i.e. a single use of the stored charge of a battery).

[0010] As the line voltage delivered to a vacuum cleaner operated from a electrical outlet (e.g. AC house current) will vary, the power control system of the instant invention may also be used to monitor the power delivered to an appliance and preferably to the suction motor and/or brush motor of a vacuum cleaner to ensure that a user obtains constant performance (e.g. constant vacuuming performance) even when the line voltage varies or their is a variation of the load seen by the brush motor as the vacuum cleaner is used to clean different surfaces (e.g. carpet having different piles). [0011] In order to achieve this result, in the case of a vacuum cleaner, at least one motor, preferably every motor and, more preferably, every electrically operated component of the vacuum cleaner which produces an effect that the user can perceive (e.g. motors and lights) is selected so as to operate at a level below a predetermined total maximum wattage which is to be drawn from the power source. If there is more than one electrically operated component, then the total maximum wattage is divided between each component and each component has a total maximum wattage that is can draw. Optionally, if one electrically operated component draws less than its permitted maximum wattage, the extra power may be diverted to one or more of the other electrically operated components.

[0012] Optionally, the vacuum cleaner may be operable in one of a plurality of possible operating modes, depending on the cleaning task, e.g. "floor cleaning" mode (i.e. when the cleaning head of the vacuum cleaner is used to clean a floor), a "high flow" or "above floor" mode for auxiliary cleaning (e.g. when a hose or wand is used to clean curtains or furniture) and a "standby"' mode for reduced speed (e.g. the suction motor may be de-energized) during interruptions in vacuuming. In such a case, the power control system is preferably designed to operate the suction motor of the vacuum cleaner at a predetermined maximum wattage in at least one of the modes and preferably in each mode incorporated in the vacuum cleaner.

[0013] In accordance with one aspect of the instant invention, a battery operated vacuum cleaner has one or both, and preferably both, a suction motor and a brush motor. The power control system reduces the power delivered to at least one, and preferably both, the suction and brush motors at the commencement of operation of the vacuum cleaner when the battery is fully charged to a level above that delivered at the end of the duty cycle of the battery so that the power delivered to the suction and brush motors remains constant as the voltage delivered by the battery drops over the cycle life of the battery. The end of the duty cycle may be when the battery drops below a preset voltage or no further power can be withdrawn from the battery without damaging the battery.

[0014] In accordance with another aspect of the instant invention, a vacuum cleaner operated on line voltage has one or both, and preferably both, a suction motor and a brush motor. The power control system reduces the power delivered to at least one, and preferably both, the suction and brush motors at the commencement of operation of the vacuum cleaner to a level above that delivered at lowest line voltage anticipated so that the power delivered to the suction and brush motors remains constant as the line voltage varies during operation of the vacuum cleaner.

[0015] In accordance with another aspect of the instant invention, the power control system for a vacuum cleaner supports communications between a micro-controller mounted in the vacuum cleaner or carpet extractor and a means for individually adjusting the voltage applied to each of the suction motor and the brush motor of said vacuum cleaner and a means for monitoring said voltage and the resulting current drawn by each of the suction motor and the brush motor. In this way, if one of the motors does not draw the total maximum wattage, then the wattage which is not drawn may be diverted to the other motor or motors.

[0016] Optionally, a user operable switch is provided to allow the user to send a signal to the microcontroller to select whether the brush motor is turned on or turned off.

[0017] Optionally, a sensing means is provided to signal the microcontroller as to the configuration of the vacuum cleaner. For example, a sensing means may be provided to signal the microcontroller when the vacuum is in the upright or storage position and a another sensing means is provided to signal the microprocessor when the above floor cleaning wand is removed from its holder for use. In response to these configuration sensors, the microcontroller will set the power levels of the suction motor and brush motor to predetermined levels to provide the user with predictable power levels for above floor cleaning, for bare floor cleaning, and for carpet cleaning.

[0018] In the case of a line voltage powered vacuum cleaner, the continual adjustment of the microcontroller to ensure that constant power is delivered to each of the brush motor and suction motor ensures the user of consistent vacuuming performance even with fluctuations in the line voltage or variations in the load seen by the brush motor as the vacuum cleaner is operated on different types of carpet.

[0019] In the case of a battery operated product, the continual adjustment of the microcontroller will ensure that the power delivered to each of the brush motor and suction motor remains constant to provide the user with consistent vacuuming performance even as the battery voltage drops during operation.

[0020] In accordance with another aspect of the instant invention, the power to the brush motor is monitored to permit the micro-controller to determine a brush jam condition when the current rapidly increases without a change in current at which time the microcontroller sets the brush voltage to zero unit the brush on/off switch is cycled indicating that the user has removed the foreign object which had jammed the brush.

[0021] In accordance with another aspect of the instant invention, means of sensing the battery voltage under load and displaying the battery status to the user is provided. Preferably, the display means comprises a single bicolor LED. The bicolor LED may be used to provide a signal to the user when the battery or battery pack is fully charged (e.g., 90 to 100% of battery capacity), when the battery or battery pack is in a useable operating rage (e.g., 20% and 90% of battery capacity) and when the battery or battery pack is approaching an end of charge state (e.g. the battery capacity is below, for example, 20%). Thus, for example, the LED may be solid green between 90 to 100% of battery capacity, flashes green between 20% and 90% of battery capacity, and, flashes yellow when the battery capacity is below 20%.

[0022] It will be understood by those skilled in the art that the power management techniques described herein may be applied to all vacuum cleaners including upright vacuum cleaners, canister vacuum cleaners, carper extractors, stick vacuums, hand vacuums, and carpet sweepers. It will be understood by those skilled in the art that the power management techniques described herein may also be applied to power tools, radios, lawn mowers, leaf blowers, computer and electronic devices or any other application where constant total power delivery is required and the voltage source may fluctuate due to brown outs on AC power grids or due to batteries being discharged.

[0023] In accordance with another aspect of the instant invention, there is provided an appliance comprising:

(a) an electrically operated member; and,

(b) a power control system electrically connectable to a power source and the electrically operated member, the power control system reducing the voltage delivered to the electrically operated member to an essentially constant level less than the voltage delivered by the power source when the appliance is actuated.

[0024] In one embodiment, the voltage is equal to or below a predetermined minimum anticipated voltage.

[0025] In another embodiment, the electrically operated member comprises a motor.

[0026] In another embodiment, the power source comprises a source of line voltage. The power source may comprise an AC source or a DC source. Preferably, the predetermined voltage is selected based on a minimum anticipated line voltage. More preferably, the electrically operated member comprises a motor and the motor is selected to operate at the minimum anticipated line voltage. [0027] In another embodiment, the power source comprises a battery having a battery voltage. Preferably, the predetermined voltage is selected based on an end of cycle voltage. More preferably, the electrically operated member comprises a motor and the motor is selected to operate at the end of cycle voltage.

[0028] In another embodiment, the power control system reduces the voltage delivered to the electrically operated, member to a level that is within 25%, more preferably within 15% of a pre-selected level (i.e. -15% to + 15% of the desired constant level).

[0029] In accordance with another aspect of the instant invention, there is provided an n appliance comprising:

(a) an electrically operated member; and,

(b) a power control system electrically connectable to a power source and the electrically operated member, the power control system reducing the voltage delivered to the electrically operated member to a level less than the voltage delivered by the power source when the appliance is actuated.

[0030] In one embodiment, the voltage is equal to or below a predetermined minimum anticipated line voltage. Preferably, the electrically operated member comprises a motor and the motor is selected to operate at the minimum anticipated line voltage.

[0031] In another embodiment the power source comprises a battery having a battery voltage and the voltage is equal to or below a predetermined minimum end of cycle voltage. Preferably, the motor is selected to operate at the end of cycle voltage.

[0032] In another embodiment the appliance is a vacuum cleaner.

[0033] In accordance with another aspect of the instant invention, there is provided a vacuum cleaner comprising:

(a) an air flow passage; (b) a suction motor positioned to draw air through the air flow passage;

(c) a battery having a battery voltage; and,

(d) a power control system electrically connected to the battery and the suction motor, the power control system reducing the voltage delivered to the suction motor to a level below the battery voltage wherein the suction motor is selected to operate at the reduced voltage.

[0034] In one embodiment, the battery has an end of life voltage and the reduced voltage delivered to the suction motor is approximately equal to or less than the end of battery life voltage.

[0035] In another embodiment, the vacuum cleaner further comprises a brush motor for moving a brush, the brush motor being powered by the battery, the power control system electrically connected to the battery and the brush motor, the power control system reducing the voltage delivered to the brush motor to a level below the battery voltage.

[0036] In accordance with another aspect of the instant invention, there is provided power control system for a battery powered apparatus, the power control system electrically connected to the battery and an electrically driven element in the apparatus, the power control system reducing the voltage delivered to the electrically driven element to a level below the battery voltage.

[0037] In another embodiment, the battery has an end of life voltage and the reduced voltage delivered to the electrically driven element is approximately equal to or less than the end of battery life voltage.

[0038] In accordance with another aspect of the instant invention, there is provided a method of vacuuming, the method comprising: (a) providing an air flow passage;

(b) coupling a suction motor to the air flow passage;

(c) connecting a battery having a battery voltage to the suction motor; and

(d) reducing the battery voltage to supply the suction motor with a reduced voltage that depends on an end of battery life voltage.

[0039] In one embodiment, the reduced voltage is approximately equal to or less than the end of battery life voltage.

[0040] In another embodiment, the method further comprises connecting the battery to a brush motor for moving a brush, and reducing the battery voltage to supply the brush motor with a second reduced voltage that depends on an end of battery life voltage.

[0041] In accordance with another aspect of the instant invention, there is provided a vacuum cleaner comprising

(a) an air flow passage;

(b) a suction motor;

(c) a brush motor for moving a brush for loosening particles to vacuum;

(d) at least one battery having a battery voltage; and,

(e) a power control system electrically connected to the battery and to the suction motor and the brush motor and having a total maximum power level, a total maximum brush motor power level and a total maximum suction motor power level, the power control system having sensors to monitor the power drawn by each of the suction motor and the brush motor and configured to deliver additional power to one of the brush motor and the suction motor if the other of the brush motor and the suction motor draws less than its respective total maximum power.

[0042] In accordance with another aspect of the instant invention, there is provided a vacuum cleaner comprising: (a) an air flow passage having an air inlet and an air outlet, the air flow passage having a suction motor and at least one filtration member provided therein;

(b) a power source for the vacuum cleaner selected from the group consisting of at least one battery and line voltage; and,

(c) a power control system electrically connected to the suction motor, the power control system limiting the power delivered to the suction motor to a level no greater than a preset power level, the preset power level selected from the group consisting of a power level corresponding to an end of life of the at least one battery and a minimum line voltage to be delivered from an electrical grid.

[0043] In one embodiment, the vacuum cleaner further comprises a cleaning head having a brush motor operatively connected to a rotatable brush and the power control system limits the power delivered to the brush motor and the suction motor to a level no greater than the preset power level.

[0044] In another embodiment, the power source for the vacuum cleaner is at least one battery and the preset power level is preset based on the end of life of the at least one battery.

[0045] In another embodiment, the vacuum cleaner further comprises a voltage sensor, a current sensor and a power regulator, the power regulator altering at least one of the voltage and the current delivered to the suction motor to maintain a constant power level delivered to the suction motor during operation of the vacuum cleaner.

[0046] In another embodiment, the vacuum cleaner has a normal operating mode, an above floor cleaning mode, a normal operating power level and an above floor power level which is different to the normal operating power level, and the power regulator alters at least one of the voltage and the current delivered to the suction motor to maintain the respective one of the normal operating power level and the above floor power level during operation of the vacuum cleaner in the normal operating mode and the above floor cleaning mode.

[0047] In another embodiment, the vacuum cleaner further comprises a voltage sensor, a current sensor and a power regulator, the power regulator altering at least one of the voltage and the current delivered to the brush motor to maintain a constant power level delivered to the during motor during operation of the vacuum cleaner when the rotatable brush is in use.

[0048] In another embodiment, the vacuum cleaner further comprises:

(a) a suction motor voltage sensor, a suction motor current sensor and a suction motor power regulator, the suction motor power regulator altering at least one of the voltage and the current delivered to the suction motor to maintain a constant power level delivered to the suction motor during operation of the vacuum cleaner; and,

(b) a brush motor voltage sensor, a brush motor current sensor and a brush motor power regulator, the power regulator altering at least one of the voltage and the current delivered to the brush motor to maintain a constant power level delivered to the brush motor during operation of the vacuum cleaner.

[0049] In another embodiment, the vacuum cleaner has a normal operating mode, an above floor cleaning mode, a normal operating power level and an above floor power level which is different to the normal operating power level, and the power regulator alters at least one of the voltage and the current delivered to the suction motor to maintain the respective one of the normal operating power level and the above floor power level during operation of the vacuum cleaner in the normal operating mode and the above floor cleaning mode.

[0050] In another embodiment, the vacuum cleaner further comprises a sensor to determine if the vacuum cleaner is in an above floor cleaning mode wherein the power control system provides at least a portion of the power which is used by the brush motor to the suction motor when the vacuum cleaner is in the above floor cleaning mode.

[0051] In accordance with another aspect of the instant invention, there is provided a programmable battery operated vacuum cleaner having a battery pack wherein at least one of performance characteristic of the vacuum cleaner is variable by changing one or both of the battery pack and the programming of the vacuum cleaner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] These and other advantages of the instant invention will be more fully and particularly understood in connection with the following description of the preferred embodiments of the invention in which:

[0053] Figure 1 is a schematic of a circuit which may be used in a power control system for a vacuum cleaner according to an embodiment of the present invention;

[0054] Figure 2 is a cross-section of a vacuum cleaner including the circuit of Figure 1 , shown operating in floor cleaning mode;

[0055] Figure 3 is a cross-section of the vacuum cleaner of

Figure 2 shown operating in standby mode;

[0056] Figure 4 is a cross-section of the vacuum cleaner of

Figure 2 operating in above floor mode with an auxiliary cleaning hose detached from the main casing;

[0057] Figure 5 is a rear view of the vacuum cleaner of Figure 2 shown operating in standby mode; and,

[0058] Figure 6a is a graph of voltage against time and Figures

6b and C are graphs of wattage against time for the duty cycle of a battery pack.

DETAILED DESCRIPTION OF THE INVENTION [0059] Referring to Figure 1 , a power control circuit 10 is shown which may be used in a vacuum cleaner in accordance with the instant invention. The vacuum cleaner may be a canister vacuum cleaner, an upright vacuum cleaner, a carpet extractor, a backpack vacuum cleaner or the like. For the purpose of this description, the invention will be described in relation to its use in an upright vacuum cleaner. It will be appreciated that the power control system of this invention is not limited to an upright vacuum cleaner and may be incorporated into another type of vacuum cleaner, a power tool or other battery operated equipment by a person skilled in the vacuum cleaner art.

[0060] Figures 2, 3 and 4 exemplify an upright vacuum cleaner that may include the circuit of Figure 1. It will be appreciated that the vacuum cleaner may be of any construction known in the art.

[0061] As shown in Figure 2, a vacuum cleaner 20 has vacuum cleaner head 22 and main casing 24. Figure 2 shows the vacuum cleaner 20 operating in the floor cleaning mode referred to earlier (i.e. cleaning head 22 is being used to clean the surface over which cleaner head 22 travels). Cleaning head 22 has rear wheels 26 and front wheels 28 to enable movement of cleaning head 22 across a surface. Cleaning head 22 is preferably provided with a rotatably mounted brush 30, which is positioned above air inlet 32 and is driven by a brush motor 31. Cleaning head 22 has an air outlet 34 positioned at the end of airflow path 36. Main casing 24 contains the filtration means, which preferably comprises a cyclone housing 40 defining a cyclone chamber 42. Cyclone chamber 92 is provided with an air inlet 44 that is in airflow communication with air outlet 46 by means of airflow path 50.

[0062] Suction is provided by a suction motor 48, which is optionally positioned above and downstream from air outlet 46. Outlet 58 from vacuum cleaner 20 is provided downstream from suction motor 48. Additional filtration means may be provided, if desired, in one or both of chambers 54 and 56. Handle 60 is provided so as to enable the vacuum cleaner to be pushed by a user. It will be appreciated that the motor may be provided at other locations in vacuum cleaner 20 and the air flow paths maybe of a different configuration.

[0063] Now referring to Figure 3, the vacuum cleaner 20 of

Figure 2 is shown in the standby mode referred to earlier. In the standby mode, the vacuum cleaner is not used to clean a surface. Instead, it is configuration in which it may be left unattended (e.g. a storage position). For example, as shown in Figure 3, rotatable valve 38 is provided in the cleaning head 22 so as to isolate the filtration means in main casing 24 from air flow path 36 when the vacuum cleaner 20 is in the upright position (i.e. the main casing 24 is positioned generally vertically over the cleaning head 22). In the case of a canister vacuum cleaner, the standby mode may be enabled by a motion sensor positioned in the cleaning head not detecting motion for a preset time of the head and handle being moved into a preset configuration (e.g. a storage position similar to the configuration of Figure 3).

[0064] A first sensing means 62 is preferably provided for sensing when the vacuum cleaner 20 is in the upright position and sends a signal to a microcontroller 64 (Figure 1) to vary the power signal to cause the motor to operate on standby, as will be explained further below. Sensing means 62 may be a micro-switch. However, any means that can be used to signal the orientation of main casing 24 or the position of main casing 24 with respect to vacuum cleaner head 22 may be used. Such means could include a mercury switch to close or open a circuit when main casing 24 is horizontal or a proximity sensor (e.g. a magnet and reed switch) mounted on cleaning head 22 to send a signal when main casing 24 is positioned proximate cleaning head 22. Preferably, a level sensor, such as a mercury switch, is utilized. More preferably, the level sensor is mounted proximate the board that houses the power control circuit 10 so as to reduce the length of wiring which must be included in the vacuum cleaner casing, thereby simplifying the wiring. More preferably, the level sensor is positioned directly on the board (such as on an I/O port of a micro-controller). One advantage of such a construction is that a wire need not be run to a sensor provided in the bottom of main casing 24 or in cleaning head 22. This facilitates the construction of the vacuum cleaner. It will be appreciated that airflow paths 36 and 50 need not be isolated to utilize the standby mode.

[0065] Now referring to Figure 4, as shown, vacuum cleaner 20 may also be adapted for above floor cleaning by means of an auxiliary cleaning hose 52, which is releasably connectable to main casing 24 by any means known in the art. Optionally, hose 52 is detachable from main casing 24, e.g., in the direction of arrow B so as to enable above the floor cleaning. Hose 52 may have a crevice cleaning tool or other attachment 53 slidably received therein in the direction of arrow C. In such a case, vacuum cleaner 20 preferably also includes a second sensing means 66 for switching motor and fan blade assembly 48 to an above floor mode when wand 52 is in use.

[0066] The higher flow is desirable for enhanced cleaning using the accessory tools 53. Alternately, as the use of a length of hose causes additional pressure losses, increasing the power provided to motor and fan blade assembly 48 may result in the same flow rate through the filtration means when hose 52 is used.

[0067] Preferably, second sensing means 66 detects that the hose 52 has been removed from its receptacle and sends a signal to the micro-controller 64 to cause the motor to operate in the above floor mode. Accordingly, second sensing means 66 may be provided in the receptacle in which hose 52 is received and actuated when hose 52 is released from the receptacle (in the direction of arrow B). Sensing means 66 may be the same or different from sensing means 62, e.g. a micro-switch, a level sensor, a proximity sensor, a pressure actuated switch (i.e. the switch may have a button which is pressed inwardly) or the like.

[0068] In the embodiment of the vacuum cleaner 20 shown in

Figure 4, it is preferable that the vacuum cleaner 20 be put into the standby mode as shown in Figure 3 for above floor cleaning so that all of the air travels through hose 52. Consequently, a vacuum cleaner 20 may go through an intermediate standby mode when switching between the floor cleaning mode and the above floor mode described above. However, it will be appreciated that this need not be the case in another vacuum cleaner configuration. In fact, it will be appreciated by those skilled in the art that power control circuit 10 of the instant application may be utilized with virtually any vacuum cleaner, such as with a vacuum cleaner using any filtration means known in the art, as well as any type of vacuum cleaner, e.g. upright, canister, back-pack and central vacuum systems.

[0069] Referring to Figure 5, in the preferred embodiment, vacuum cleaner 20 is provided with a main on/off switch 70. In addition, if the vacuum cleaner includes a brush motor 31 , then a separate brush motor on/off switch 72 is preferably provided. Brush motor on/off switch 72 permits a user to selectively energize or de- energize brush motor 31 depending upon the cleaning requirements (e.g., if vacuum cleaner 20 is to be used to clean a carpeted surface or a wood floor). Alternately, or in addition, brush motor 31 may be selectively de-energized automatically upon main casing 24 being moved into the standby mode position shown in Figure 3.

[0070] The vacuum cleaner is preferably operated by at least one battery and, more preferably, by a plurality of batteries, which may be provided in battery pack 74. Preferably the batteries are rechargeable. Battery pack 74 may be provided at any position on vacuum cleaner 20. For example, as shown in Figure 5, battery pack 74 may be mounted at the rear of main casing 24. However, it will be appreciated by those skilled in the art that, for the purpose of this invention, battery pack 74 may be provided at any location on the vacuum cleaner and may be removably mounted (so that it is removed for charging) or may be fixedly mounted (i.e. it is charged in situ). In an alternate embodiment, the vacuum cleaner may be powered by line voltage e.g., it may be plugged into an electrical outlet in the user's house).

[0071] In accordance with one embodiment of this invention, suction motor 48 is selected to operate on a wattage which is the same as or less than a preset maximum power level (or maximum total wattage) which the vacuum cleaner may draw during operation. If vacuum cleaner 20 has more than one electrical component (e.g. a motor or a light), then each electrical component is selected so as to operate on a maximum total wattage that, when combined, is the same as or less than a preset maximum power level which the vacuum cleaner may draw during operation. If one embodiment, the vacuum cleaner has a suction motor 48 and a brush motor 31 and an optional headlight and at least the motors 31 and 48 are selected so as to operate on a maximum total wattage that, when combined, is the same as or less than a preset maximum power level which the vacuum cleaner may draw during operation. Thus, the brush motor 31 is selected to operate at a brush motor maximum wattage and suction motor 48 is selected to operate at a suction motor maximum wattage wherein the brush motor maximum wattage and the suction motor maximum wattage is the same as or less than the total maximum wattage.

[0072] Accordingly, the electricity, which is delivered to suction motor 48 is regulated by a power control system that is electrically connected to suction motor 48. The power control system limits the power delivered to the suction motor to a level no greater than a preset power level (the suction motor maximum wattage). If vacuum cleaner 20 is powered by at least one battery, then the preset power level corresponds to an end of life (or end of charge state) of the at least one battery. If vacuum cleaner 20 is powered by line voltage, then the preset power level corresponds to a minimum line voltage to be delivered from an electrical grid.

[0073] By limiting the power delivered to suction motor to the lowest power level that suction motor will experience during its operation, the cleaning performance of the vacuum cleaner will not decrease during its operation. Dirt is entrained in the air stream at the dirty air inlet to vacuum cleaner 20. As the rate of travel of the air stream decreases, then the amount of dirt that is entrained in the air stream decreases and the cleaning efficiency decreases. If vacuum cleaner is battery operated, then by operating vacuum cleaner 20 in accordance with this aspect of the invention, the airflow rate at the dirty air inlet (and therefore the cleaning efficiency) will not decrease over the duty cycle of the batteries, provided that there is no increase in air flow restrictions in the air flow path through vacuum cleaner 20 (e.g., the air passage is not clogged). As the pressure drop across a cyclone remains relatively constant as the cyclone accumulates separated dirt, the power control system is preferably used with a vacuum cleaner that includes cyclonic filtration (i.e. at least one cyclone).

[0074] Another advantage of the instant invention is that by limiting the total maximum wattage that the vacuum cleaner may draw from a battery pack, the run time of vacuum cleaner 20 may be predicted. Once the capacity of the battery pack is known, then assuming that vacuum cleaner 20 will draw essentially the maximum total wattage at all times when it is operated, the operating life of vacuum cleaner 20 on a single charge of the battery pack may be calculated and the vacuum cleaner will provide such an operating life until the batteries in the battery pack exceed their usable recharge cycles.

[0075] In accordance with another embodiment of this invention, vacuum cleaner 20 also includes a brush motor 31 and a brush 30. In such a case, the power control system preferably also limits the power delivered to brush motor 31 to a level no greater than a brush motor preset power level or total maximum wattage. If vacuum cleaner 20 is battery operated, then by operating brush motor 31 in accordance with this aspect of the invention, the rate of rotation of brush 30 will remain constant over a cycle of the batteries, provided brush 30 is not jammed. As the rate of rotation of brush 30 affects the ability of the air stream to entrain dirt, maintaining a constant rate of rotation of brush 30 will prevent a drop off in cleaning efficiency during periods of operation when the power delivered from the power source decreases within expected operating limits.

[0076] Accordingly, if the power control system is used to control both the suction motor and the brush motor, then the power control system may be programmed to have both a suction motor preset total maximum wattage and a brush motor preset total maximum wattage which may total an overall preset power level (total maximum wattage) which corresponds to an end of life (or end of charge state) of the at least one battery or a minimum line voltage to be delivered from an electrical grid. It will be appreciated that if vacuum cleaner includes lights, the power control system may also incorporate a light preset total maximum wattage to provide an even level of illumination during the operation of the vacuum cleaner.

[0077] If the vacuum cleaner has a plurality of preset total maximum wattages (one for each electrically powered element), then the power control system is configured to power in parallel each electrically powered element. In the embodiment of Figure 1 , the vacuum cleaner has a brush motor 31 and a suction motor 48. Accordingly the following discussion is premised on such a configuration of a vacuum cleaner. It will be appreciated by those skilled in the art that the power control system of Figure 1 may be varied to produce a power control system for each variant discussed herein.

[0078] In the embodiment of Figure 1 , circuit 10 which delivers power to brush motor 31 is provided with brush motor line current sensor 80 and brush motor line voltage sensor 82 so as to monitor the current and voltage provided to brush motor 31. Similarly, the current and voltage delivered to suction motor 48 is monitored by suction motor line current sensor 84 and suction motor line voltage sensor 86. Voltage sensors 82, 86 may be a comparator. Current sensors 80, 84 may operate by converting the current to a voltage signal, which is then be measured by a comparator. The conversion of current to voltage may be achieved by means of a low value resistor across which a voltage drop proportional to the current occurs. Alternately, a magnetic sensor such as a hall effect sensor may be used to measure the magnetic field created when the current alternates due to pulse width modulation control wherein the field is proportional to the current.

[0079] Preferably, the power control system adjusts the operation of the motors so as to draw essentially the total maximum wattage at all times. In this way, vacuum cleaner 20 will always operate for the same amount of time between recharges. For example, if the load on brush motor 31 is reduced (e.g. vacuum cleaner 20 is moved from cleaning a high pile carpet to a low pile carpet or a bare floor), then the rate of rotation of brush 30 will increase. To prevent brush motor 31 from rotating too fast, a maximum voltage level is preferably preset. Thus, when, for example, vacuum cleaner 20 is used to clean a bare floor and brush 30 is allowed to rotate, brush motor 31 will not draw the total maximum wattage since the voltage which is can draw is also limited. In such cases, the extra available wattage is preferably provided to suction motor 48. Thus suction motor 48 will cause an increase flow rate of air into inlet 32 which will enhance cleaning of bare floors.

[0080] Accordingly, a maximum total wattage for the system is predetermined. In addition, a maximum wattage for each motor is predetermined. Circuit 10 determines the wattage drawn by the brush motor 31 (up to the maximum brush motor total maximum wattage) and sets the voltage which brush motor 31 may draw so as to produce the brush motor maximum total wattage or the brush motor maximum total voltage if the brush motor maximum total wattage does not occur at a voltage below the brush motor maximum total voltage. Circuit 10 then preferably calculates the power available for suction motor 48 by subtracting the actual wattage drawn by brush motor 31 from the maximum total wattage to derive a calculated permissible wattage for suction motor 48. Circuit 10 then sets the actual voltage drawn by suction motor 48 to a level, which produces the calculated permissible wattage for the suction motor 48. Thus the system always provides a maximum wattage, which ensures that the battery life predicted for the device is maintained and that the maximum possible power available is distributed between the brush motor 31 and suction motor 48 so as to provide the maximum possible cleaning power for cleaning.

[0081] In order to individually vary the power delivered to suction motor 48 and brush motor 31 , a suction motor power regulator 76 and a brush motor power regulator 78 are provided. Preferably the voltage is varied, such as by the use of pulse width modulation (such as that taught in United States Patent 6,307,358, the disclosure of which is incorporated herein by reference). Alternately, the voltage may be varied by use of a DC chopping circuit combined with a variable inductor, the use of a chopping circuit and a variable transformer, by control of separate phases of a multiphase motor or by the electrical connection to separate windings on a motor designed to produce a preset power level.

[0082] Preferably, circuit 10 includes a micro-controller 64, which receives an input from each of the sensors on a periodic basis (e.g., every 10 ms) and sends an output to one or both of power regulator 76 and 78 to maintain the predetermined wattage or the calculated wattage as the load produced by the motor varies. Microcontroller 64 may not be programmable and may be hard wired with the predetermined wattages. Preferably, micro-controller 64 is programmable so that different predetermined wattages for each of the electrically powered elements may be programmed into microcontroller 64. It will be understood by those skilled in the art that this logic may be accomplished by discrete logic elements such as transistors rather than by a micro-controller.

[0083] By varying the rate at which power is drawn from battery pack 74, one or more performance characteristics of vacuum cleaner 20 may be varied. For example, by increasing one or all of the preset power levels, the cleaning efficiency of vacuum cleaner 20 may be improved (e.g., the rate of rotation of suction motor 48 may be increased to produce a higher air flow and/or the rate of rotation of brush 30 may be increased to enhance the rate at which dirt is dislodged from carpet). By drawing additional current from battery pack 74, the duty cycle of battery pack is shortened (e.g., the life of battery pack 74 may decrease from 30 minutes to 20 minutes). Alternately, the operating time of a vacuum cleaner on a single charge may be extended by reducing one or all of the preset power levels. Accordingly, in accordance with another embodiment of this invention, a vacuum cleaner having different characteristics may be developed merely by changing the programming of a micro-controller or merely by changing a circuit board. The change in programming may be used to create a different model of vacuum cleaner using the identical (or similar) manufactured components. Thus the change in programming can be used to produce a family of vacuum cleaners from a single set of molds.

[0084] Alternately, or in addition, the number of type of batteries in battery pack 74 may be varied. For example, to produce a lower cost machine for cleaning smaller areas, fewer batteries may be included in a battery pack 74. To produce a vacuum cleaner having a longer operating life on a single charge, batteries having a higher amperage may be used (e.g. 5 amp hour batteries instead of 4.3 amp hour batteries). Accordingly, in accordance with another embodiment of this invention, a vacuum cleaner having different characteristics may be developed merely by changing the battery pack for a vacuum cleaner. The change in battery pack may be used to create a different model of vacuum cleaner using the identical (or similar) manufactured components. Thus the change in battery pack can be used to produce a family of vacuum cleaners from a single set of molds.

[0085] Alternately, both the battery pack and the programming may be altered to enhance the number of different vacuum cleaners that may be manufactured from a single set of molded parts. [0086] In order to provide information to the user about the status of the battery and/or other operating feature of the vacuum cleaner, one or more lights may be provided. Preferably, the lights are LEDs. For example, as shown in Figure 1 , power control circuit 10 may include power level LED 88 to advise a user as to the status of battery pack 74. A brush roll LED 90 may also be provided to advise a user if brush 30 ceases to rotate because, for example, it is jammed.

[0087] In operation, micro-controller 64 is preferably programmed with a preset power level for each motor. If the vacuum cleaner is powered by battery pack 74, then the power level is preferably selected based upon an end of cycle power level (i.e. the power level at about which battery pack 10 will cause vacuum cleaner 20 to turn off and, preferably, at a level below which circuit 10 will cause vacuum cleaner 20 to turn off).

[0088] For example, if vacuum cleaner 20 only has one electrically operated element (i.e. suction motor 48), then battery pack 74 may comprise twelve 1.2 volts sub-C battery. Accordingly, when battery pack 74 is fully charged, it is fully capable of delivering 14.4 volts. At the end of a cycle of the batteries, the voltage which battery pack 74 is capable of providing may have decreased to, for example 12 volts. In such a case, the preset power level may be set to approximately 12 volts and, preferably, slightly less than 12 volts (e.g., 11.9 volts). In the case of a vacuum cleaner that is operated by line voltage, in the case of North American AC voltage, the line voltage that is actually delivered by an electrical grid may in the range 98 - 140 volts. In such a case, the preset power level may be set at about the minimum power level that is reasonably anticipated to be delivered by the electrical grid.

[0089] Alternately, in this example, if vacuum cleaner 20 has two electrically operated elements (e.g., suction motor 48 and brush motor 31) then the suction motor preset power level may be set to approximately 10 volts and, preferably, slightly less than 10 volts (e.g., 9.9 volts) and the brush motor preset power level may be set to approximately 2 volts and, preferably, slightly less than 2 volts (e.g. 1.9 volts).

[0090] Current sensor 80 and voltage sensor 82 are monitored by micro-controller 64. By combining the signals from sensor 80 and 82, the wattage that is drawn by brush motor 31 may be monitored. Similarly, the wattage drawn by suction motor 48 may be monitored by sensors 84 and 86. Micro-controller 64 is programmed with a preset total maximum wattage to be delivered to brush motor 31 and a second pre-set total maximum wattage desired to be delivered to suction motor 48.

[0091] Thus, an advantage of circuit 10 is that by limiting the total wattage delivered to suction motor 48 and brush motor 31 when battery pack 74 is at the beginning of an operation cycle, the user will not detect an decrease in the performance of the vacuum cleaner over the life of a cycle of battery pack 74 as the voltage which battery pack 74 is capable of delivering decreases.

[0092] In addition, a further advantage of circuit 10 is that the power delivered to suction motor 48 and brush motor 31 are independently controlled. If brush 30 becomes jammed, brush motor 31 will not draw an excess of power thereby reducing the power available to suction motor 48 and, consequently decreasing the suction produced by suction motor 48. Similarly, if a blockage occurs in suction motor 48, suction motor 48 will not draw an excess of power thereby reducing the power drawn by brush motor 31 and, accordingly, the rate of rotation of brush 30.

[0093] If a blockage occurs in an airflow path, then the mass flow rate will drop and this will drop the current drawn by suction motor 48. For example, suction motor 48 may be a 10 volt motor and may draw about 20 amps when wand 52 is used for cleaning and the airflow passage through the vacuum cleaner is not blocked (i.e. about 200 watts). If the airflow passage is blocked, e.g. the wand becomes clogged or a user covers the open end of wand 52, then the mass flow rate will drop and the current drawn by motor 48 will decrease (e.g. to about 12 amps). In order to maintain the wattage at the pre-set power level for suction motor 48, micro-controller 64 automatically increases the voltage delivered to suction motor 48 so as to maintain the wattage at the preset power level (200 watts). The increased voltage will increase the suction produced by suction motor 48 in this sealed suction state.

[0094] Similarly, if brush 31 becomes entangled in the carper or the like, then its rate of rotation will decrease or, it may completely stop turning. In such a case, the current drawn by brush motor 31 will rapidly increase. In order to maintain the wattage at the preset level, micro-controller 64 may reduce the voltage delivered to brush motor 31. In the case of a complete jam, then the voltage is preferably reduced to 0 whereby this would prevent brush motor 31 trying to rotate the jammed brush thereby preventing damage to brush motor 31. At the same time, micro-controller 64 could use these current and/or voltage conditions to energize brush roll LED 90 to advise a user of the brush jam condition.

[0095] Preferably, circuit 10 is constructed to prevent vacuum cleaner 20 from operating if battery pack 74 is below a predetermined charge state. More preferably, a signal is provided to the user to advise the user of the charge state of battery pack 74.

[0096] Figure 6a shows two voltage versus time plots of a typical battery for a single duty cycle. Figure 6b shows several wattage versus time plots for a suction motor for a vacuum cleaner for a single duty cycle for a battery. Figure 6c shows several wattage versus time plots for a brush motor for a vacuum cleaner for a single duty cycle for a battery.

[0097] Referring to Figure 6a, for the first time plot 92, two time intervals are shown. The first time interval corresponds to the lifetime 96 of the battery, and the second time interval to the decay interval 98 of the battery. The lifetime 96 of the battery is typically longer than the decay interval of the battery, the exact times depending on the type of battery, the frequency that power is drawn from the battery, and the like as is known in the art. Additionally, the first time interval 96 is also characterized by a smaller rate of voltage decrease than the second time interval 98.

[0098] Time plot 92 assumes that the battery powers a vacuum cleaner having a rotating brush 30 and a suction motor 48 but which does not have the power control system of the instant invention. In time plot 92, the vacuum cleaner is used to clean a low pile carpet. The wattage drawn by the suction motor is shown in Figure 6b (line 100) and the wattage drawn by the brush motor is shown in Figure 6c (line 102).

[0099] In time plot 94, the vacuum cleaner is used to clean a high pile carpet. The high pile carpet produces a greater load on brush motor 31 resulting in a shorter duty cycle for the battery. The wattage drawn by the suction motor is shown in Figure 6b (line 104) and the wattage drawn by the brush motor is shown in Figure 6c (line 106).

[00100] In accordance with the instant invention, the power control system limits the total wattage that may be drawn from the battery and distributes it to suction motor 48 and brash motor 31 so as to produce a constant run time regardless of the surface to be cleaned. For example, when the vacuum cleaner is used to clean a low pile carpet, the wattage drawn by the suction motor may be represented by line 108 in Figure 6b and the wattage drawn by the brush motor may be represented by line 110 in Figure 6c. When the vacuum cleaner is used to clean a high pile carpet, then the brush is required to do more work to assist in dislodging dirt to be entrained in the air stream entering inlet 32. Thus the power that is delivered to brush motor 31 is increased (line 114) and the power delivered to suction motor 48 is decreased (line 112). When cleaning low pile carpet or bare increased efficiency is achieved by increasing the air flow rate at inlet 32. As the brush encounter less resistance to rotation on these surfaces, additional power may be applied to suction motor 48 to enhance cleaning efficiency on these surfaces. In either case, the total maximum wattage is pre-selected. The voltage profile may be that set out in line 92 to provide a 20 minute run time regardless of the surface to be cleaned.

[00101] One mode of operating circuit 10 will now be discussed by reference to Figure 1. Initially, a user will turn on the vacuum cleaner by pressing main on/off switch 70. Controller 64 will check the charge state (e.g., voltage) of battery 74. If the voltage of battery pack 74 is greater than a first pre-set charge state, then power level LED 88 issues a first signal to the user (e.g. it may be energized to provide a solid colour). If LED 88 is a bi-colour LED (e.g. a yellow/green LED), then LED 88 may be energized to a first solid colour (e.g. green). The first pre-set charge state level indicates that the battery pack is fully charged or essentially fully charged. The first pre-set charge state level may be set based upon battery pack 74 being charged to, for example, 90 percent or more of a full charge. Accordingly, when a user turns on the vacuum cleaner, LED 88 will, for example, turn green if a battery pack is essentially fully charged.

[00102] Micro-controller 64 is preferably also programmed with a second preset charge state. This charge state corresponds with a usable operating range for the batteries (e.g. the battery contains, for example, 20% to 90% of a full charge). At such a charge state, LED 88 preferably emits a different signal (e.g. it may flash green).

[00103] If the charge state of battery pack 74 is less than the bottom range of the second preset charge state, then a different signal may be sent to a user. For example, the bottom range of the second preset charge state may be a level which requires battery pack 74 to be recharged or which will not provide the user with much operating time (e.g. battery pack 74 contains about 20% or less of a standard charge). In such a case, LED 88 may emit a third visual signal and/or an audible signal (e.g. a buzzer) may be actuated. In such a case, micro-controller 64 is preferably programmed to turn vacuum cleaner 20 off, thereby requiring the user to recharge battery pack 74. [00104] If battery pack 74 contains sufficient voltage to permit the operation of a vacuum cleaner, then micro-controller 64 preferably then determines the configuration of the vacuum if the vacuum cleaner includes one or both of sensors 62 and 66. For example, microcontroller 64 preferably checks to determine if vacuum cleaner 20 is in an upright position as shown in Figure 3 by means of first sensor 62. If vacuum cleaner 20 is in the upright position, then micro-controller 64 preferably turns off brush motor 31 and, also, in addition suction motor 48. Thus, micro-controller 64 automatically switches vacuum cleaner 20 to the standby mode.

[00105] If micro-controller 64 switches the vacuum cleaner to the standby mode, then micro-controller 64 preferably checks to determine if the vacuum cleaner is in the above floor cleaning mode. To do this, micro-controller 64 uses second sensor 66 to determine whether wand 52 has been removed from its storage position in vacuum cleaner 20. If the wand is still in its storage position, then the vacuum cleaner is maintained in the standby mode and micro-controller 64 cyclically checks the configuration of the vacuum cleaner via sensors 62 and 66 to determine when the vacuum cleaner is placed in one of the operating modes.

[00106] When the vacuum cleaner is moved into the floor cleaning operating position as shown in Figure 2, a signal is detected via sensor 62 which causes micro-controller 64 to engage brush motor 31 and suction motor 48. At this time, suction motor 48 is preferably energized to a suction motor preset power level. If the vacuum cleaner is to be used to clean a bare floor, or the rotation of brush 30 is not desired, a user may manually disengage the brush by pressing brush on/off switch 72. Alternately, if a user disengages the hose, then microcontroller 64 detects this via sensor 66. At that time, micro-controller 64 energizes suction motor 48 to a suction motor preset power level. In order to provide enhanced suction when wand 52 is used, microcontroller may be preprogrammed with two suction motor preset power levels - a first (floor cleaning) lower level when the vacuum cleaner is used in the floor cleaning mode (i.e. a brush is available to assist in the cleaning) and a second (above floor) higher level for use with a wand.

[00107] In accordance with one aspect of the instant invention, regardless of the configuration of the vacuum cleaner, power control circuit 10 is used to adjust the voltage delivered to the suction motor (either up or down) to achieve the preset total maximum wattage which is programmed into micro-controller 64.

[00108] If the vacuum cleaner is moved from standby position into the floor cleaning operating mode position as shown in Figure 2, then micro-controller preferably checks to determine whether brush on/off switch 72 is actuated. If switch 72 is set to the "on" position, then micro-controller 64 energizes brush motor 31 to a brush motor preset power level. At this time, brush roll LED 90 may be actuated to provide a first visual signal to a user (e.g. it may be turned to a solid colour). If it is a bi-colour LED, then it may be set to a first colour (e.g. green).

[00109] In accordance with one preferred embodiment of the instant invention, micro-controller 64 monitors the wattage delivered to brush motor 31 and adjusts the voltage (up or down) to achieve the predetermined brush motor total maximum wattage (brush motor preset power level). If the brush motor wattage is greater than the preset brush t otor total maximum wattage, then the brush voltage may be set to 0 and a second visual signal may be provided, for example, LED 90 flashing or changing colour (or both) to indicate a brush jam. When the brush jam is cleared, then the current drawn by brush motor 31 will decrease. Upon detecting this, micro-controller 64 may increase the voltage delivered to brush motor 31 permitting brush motor 31 to re-commence driving brush 30.

[00110] In accordance with another aspect of this invention, the preset power level for suction motor 48 and brush motor 31 may vary depending upon the configuration of a vacuum cleaner. For example, if the vacuum cleaner is in the standby mode, the preset wattage is preferably 0 (e.g., the voltage is reduced to 0 when the vacuum cleaner is in the standby mode). This minimizes the power that is drawn from battery pack 74 when the vacuum cleaner is not being used to clean and maximizes the operating time that is available to a user from battery pack 74. Preferably, brush motor 31 is not energized when the vacuum cleaner is in the above the floor cleaning mode.

[00111] In one embodiment, preferably some or all of the power that is utilized to operate brush motor 31 in the floor cleaning mode shown in Figure 2 is diverted to suction motor 48 in the above floor cleaning mode. This may be achieved by presetting a higher total maximum wattage (an above floor total maximum wattage), which is monitored by micro-controller 64 via sensor 84 and 86 when the vacuum cleaner is in the above floor cleaning mode. Thus, the suction which is available through wand 52 in the above floor cleaning mode may be enhanced by providing additional power to suction motor 48. Alternately, it will be appreciated by those skilled in the art that suction motor 48 may continue to operate at the "floor cleaning" operating mode (i.e. at the floor cleaning total maximum wattage) in the above floor cleaning mode thereby extending the operating time of the vacuum cleaner.

[00112] According to one aspect of the instant invention, the motor control circuit may be utilized with a vacuum cleaner that is to be plugged into a standard electrical outlet in a house. In such a case, the power control system may be designed to provide full power to the suction motor in the above floor cleaning mode and to reduce the power provided to the motor in the floor cleaning mode.

Claims

Claims:

I . An appliance comprising:

(a) an electrically operated member; and, (b) a power control system electrically connectable to a power source and the electrically operated member, the power control system reducing the voltage delivered to the electrically operated member to an essentially constant level less than the voltage delivered by the power source when the appliance is actuated. 2. The appliance as claimed in claim 1 wherein the voltage is equal to or below a predetermined minimum anticipated voltage.

3. The appliance as claimed in claim 1 wherein the electrically operated member comprises a motor.

4. The appliance as claimed in claim 2 wherein the power source comprises a source of line voltage.

5. The appliance as claimed in claim 4 wherein the power source comprises an AC source.

6. The appliance as claimed in claim 4 wherein the power source comprises a DC source. 7. The appliance as claimed in claim 4 wherein the predetermined voltage is selected based on a minimum anticipated line voltage. 8. The appliance as claimed in claim 7 wherein the electrically operated member comprises a motor and the motor is selected to operate at the minimum anticipated line voltage. 9. The appliance as claimed in claim 2 wherein the power source comprises a battery having a battery voltage. 10. The appliance as claimed in claim 9 wherein the predetermined voltage is selected based on an end of cycle voltage.

I I . The appliance as claimed in claim 10 wherein the electrically operated member comprises a motor and the motor is selected to operate at the end of cycle voltage.

12. The appliance as claimed in claim 9 wherein the power control system reduces the voltage delivered to the electrically operated member to a level that is within 15% of a pre-selected level.

13. An appliance comprising: (a) an electrically operated member; and,

14. The appliance as claimed in claim 13 wherein the voltage is equal to or below a predetermined minimum anticipated line voltage.

15. The appliance as claimed in claim 14 wherein the electrically operated member comprises a motor and the motor is selected to operate at the minimum anticipated line voltage.

16. The appliance as claimed in claim 13 wherein the power source comprises a battery having a battery voltage and the voltage is equal to or below a predetermined minimum end of cycle voltage.

17. The appliance as claimed in claim 16 wherein the motor is selected to operate at the end of cycle voltage.

18. The appliance as claimed in claim 13 wherein the appliance is a vacuum cleaner.

19. A vacuum cleaner comprising: (a) an air flow passage; (b) a suction motor positioned to draw air through the air flow passage;

(c) a battery having a battery voltage; and,

20. The vacuum cleaner of claim 19, wherein the battery has an end of life voltage and the reduced voltage delivered to the suction motor is approximately equal to or less than the end of battery life voltage.

21. The vacuum cleaner of claim 19, further comprising a brush motor for moving a brush, the brush motor being powered by the battery, the power control system electrically connected to the battery and the brush motor, the power control system reducing the voltage delivered to the brush motor to a level below the battery voltage.

22. A power control system for a battery powered apparatus, the power control system electrically connected to the battery and an electrically driven element in the apparatus, the power control system reducing the voltage delivered to the electrically driven element to a level below the battery voltage.

23. The apparatus of claim 22, wherein the battery has an end of life voltage and the reduced voltage delivered to the electrically driven element is approximately equal to or less than the end of battery life voltage.

24. A method of vacuuming, the method comprising:

(a) providing an air flow passage;

(b) coupling a suction motor to the air flow passage; (c) connecting a battery having a battery voltage to the suction motor; and

25. The method of claim 24, wherein the reduced voltage is approximately equal to or less than the end of battery life voltage.

26. The method of claim 6, further comprising connecting the battery to a brush motor for moving a brush, and reducing the battery voltage to supply the brush motor with a second reduced voltage that depends on an end of battery life voltage.

27. A vacuum cleaner comprising (a) an air flow passage;

(b) a suction motor;

(c) a brush motor for moving a brush for loosening particles to vacuum;

(d) at least one battery having a battery voltage;

28. A vacuum cleaner comprising:

(a) an air flow passage having an air inlet and an air outlet, the air flow passage having a suction motor and at least one filtration member provided therein;

29. The vacuum cleaner as claimed in claim 28 further comprising a cleaning head having a brush motor operatively connected to a rotatable brush and the power control system limits the power delivered to the brush motor and the suction motor to a level no greater than the preset power level.

30. The vacuum cleaner as claimed in claim 28 wherein the power source for the vacuum cleaner is at least one battery and the preset power level is preset based on the end of life of the at least one battery.

31. The vacuum cleaner as claimed in claim 28 further comprising a voltage sensor, a current sensor and a power regulator, the power regulator altering at least one of the voltage and the current delivered to the suction motor to maintain a constant power level delivered to the suction motor during operation of the vacuum cleaner.

32. The vacuum cleaner as claimed in claim 31 wherein the vacuum cleaner has a normal operating mode, an above floor cleaning mode, a normal operating power level and an above floor power level which is different to the normal operating power level, and the power regulator alters at least one of the voltage and the current delivered to the suction motor to maintain the respective one of the normal operating power level and the above floor power level during operation of the vacuum cleaner in the normal operating mode and the above floor cleaning mode.

33. The vacuum cleaner as claimed in claim 30 further comprising a voltage sensor, a current sensor and a power regulator, the power regulator altering at least one of the voltage and the current delivered to the brush motor to maintain a constant power level delivered to the during motor during operation of the vacuum cleaner when the rotatable brush is in use.

34. The vacuum cleaner as claimed in claim 30 further comprising: (a) a suction motor voltage sensor, a suction motor current sensor and a suction motor power regulator, the suction motor power regulator altering at least one of the voltage and the current delivered to the suction motor to maintain a constant power level delivered to the suction motor during operation of the vacuum cleaner; and,

35. The vacuum cleaner as claimed in claim 34 wherein the vacuum cleaner has a normal operating mode, an above floor cleaning mode, a normal operating power level and an above floor power level which is different to the normal operating power level, and the power regulator alters at least one of the voltage and the current delivered to the suction motor to maintain the respective one of the normal operating power level and the above floor power level during operation of the vacuum cleaner in the normal operating mode and the above floor cleaning mode.

36. The vacuum cleaner as claimed in claim 30 further comprising a sensor to determine if the vacuum cleaner is in an above floor cleaning mode wherein the power control system provides at least a portion of the power which is used by the brush motor to the suction motor when the vacuum cleaner is in the above floor cleaning mode.

37. A programmable battery operated vacuum cleaner having a battery pack wherein at least one of performance characteristic of the vacuum cleaner is variable by changing one or both of the battery pack and the programming of the vacuum cleaner.