WO2024121716A1

WO2024121716A1 - A cleaning appliance

Info

Publication number: WO2024121716A1
Application number: PCT/IB2023/062190
Authority: WO
Inventors: Andrew SPILLMAN; Christopher Bateman; Kevin MARTÍN DÍAZ
Original assignee: Dyson Technology Limited
Priority date: 2022-12-09
Filing date: 2023-12-04
Publication date: 2024-06-13
Also published as: GB202218524D0; GB2625146A

Abstract

The present invention relates to a cleaning appliance and particularly, although not exclusively, to a cleaning appliance which comprises an improved system for identifying a connected cleaner head. For example, the cleaning appliance comprises a main body for connecting to a cleaner head, the main body comprising a controller, and a plurality of conductors for conveying power from the main body to a cleaner head, wherein the plurality of conductors comprises a first conductor which is switchable by the controller to operate as each of: a power line for conveying power to the cleaner head, and a communications channel between the main body and the cleaner head.

Description

A CLEANING APPLIANCE

Field of the Invention

The present invention relates to a cleaning appliance and particularly, although not exclusively, to a cleaning appliance which comprises an improved system for identifying a connected cleaner head.

Background

Existing cleaning appliances have limited ways to identify a cleaner head which is attached to a main body, and are also limited in how power may be delivered from the main body to a cleaner head.

For example, in certain known appliances, two wires pass from the main body of the cleaning appliance to a cleaner head. One wire can be used as a positive direct current (DC) or pulse width modulation (PWM) power wire, and the second wire is used as a return wire. In such arrangements, brushed motors and DC loads (e.g. lights), or brushless motor drive circuits (e.g. for a brushless DC, BLDC, motor) can be powered, and the type of cleaner head can be identified based on the input impedance detected at the main body. A brushed motor, for example, may have an inductive impedance, whereas a drive circuit for a BLDC may have a large capacitive impedance.

As cleaning appliances are now supplied with a large number of cleaner heads which are adapted to perform different tasks, and which may comprise a range of different motors and may have different power requirements, for example, there is a growing need to uniquely identify different cleaner head variants. Impedance-based measurements as described above are insufficient to identify such a variety of cleaner heads. For example, impedance-based measurements may be unsuitable for differentiating different cleaner heads which comprise similar motors, or different cleaner heads which comprise no motor.

The present invention has been devised in light of the above considerations.

Summary of the Invention

According to a first aspect of the present invention, there is provided a cleaning appliance, for example a vacuum cleaner, comprising a main body for connecting to a cleaner head, the main body comprising a controller, and a plurality of conductors for conveying power from the main body to a cleaner head, wherein the plurality of conductors comprises a first conductor which is switchable by the controller to operate as each of: a power line for conveying power to the cleaner head, and a communications channel between the main body and the cleaner head. By being provided in this way, a cleaning appliance according to the first aspect is able to identify a wide range of cleaner heads which may be connected to the main body, and, where appropriate for an identified cleaner head, provide power to said cleaner heads in a manner as set out in more detail below. In particular, the first conductor may be used to help identify a connected cleaner head (for example, the controller may utilise the first conductor to identify a cleaner head according to methods described in more detail below) and, responsive to the determination, may be used to provide power to the cleaner head or to act as a communications channel between the main body and the cleaner head. The term ‘tool’ may also be used herein to refer to a cleaner head.

A cleaning appliance may be a vacuum cleaner, and, more specifically, may be a “stick-vac” type vacuum cleaner of the general type comprising a handheld vacuum cleaner which is attached to an elongate, rigid wand and which is fluidly connected to a cleaner head provided at the end of the wand. In such vacuum cleaners, a cleaner head may be connected directly to the main body or, in some arrangements, may be connected to the main body via a rigid wand. Of course, it will be appreciated that the teachings of the present invention are not limited to such “stick-vac” type vacuum cleaners, and may be applied to any suitable cleaning appliance or vacuum cleaner comprising a main body for connecting to a cleaner head. An example of such a vacuum cleaner may be found in US 8347455 B2 or US 9301665 B2.

Optionally, the main body may comprise a three-phase inverter connected to deliver three-phase alternating current (AC) power to the plurality of conductors. By being provided in this way, the cleaning appliance may be more ergonomic, as the weight of a three-phase inverter for driving a BLDC motor in a cleaner head is provided in the main body, and not in the cleaner head itself as in known arrangements. In particular, for “stick-vac” type vacuum cleaners, the main body is held by a user (e.g. with a handle), whereas the cleaner head is at a distance from the main body, and so by concentrating more weight in the main body the cleaning appliance is easier to hold and manipulate. In addition, by providing the three- phase inverter in the main body, the cleaner head itself may be simpler and less expensive to manufacture.

Optionally, the plurality of conductors may be a plurality of wires.

Optionally, the plurality of conductors may comprise three conductors, and the first conductor which is switchable by the controller may be a first conductor of the three conductors. In this way, the plurality of conductors may be used for power, using either two conductors or three conductors, and communications, using the first conductor. In particular, implementing the plurality of conductors as three conductors provides a relatively simple to engineer arrangement, for example where the three conductors are to be passed along a wand of a “stick-vac” type vacuum cleaner, and may allow a relatively cheap and simple three-pin electrical connection between the main body and the cleaner head. Using the first conductor for communications may enable half-duplex bidirectional communication between the main body and a cleaner head in a manner described in more detail below.

In certain embodiments, the cleaning appliance may be operable in each of two modes, wherein: in a first mode, three-phase AC power is delivered from the main body to a cleaner head using the three conductors, and in a second mode, communications between the main body and the cleaner head may be performed using the first conductor, and power may be delivered from the main body to a cleaner head using the remaining two conductors. In this way, the cleaning appliance is adapted to work with a variety of cleaner heads having different power requirements and communications capabilities. For example, the cleaning appliance is configured deliver three-phase power to a cleaner head having a BLDC motor, or single-phase power to a cleaner head having a brushed motor or other DC load while also allowing communications with the cleaner head, e.g. for diagnostics and/or telemetry data to be communicated to the main body.

Optionally, the plurality of conductors may comprise three wires, and the first conductor which is switchable by the controller may be a first wire of the three wires. In this way, the plurality of conductors may be used for power, using either two wires or three wires, and communications, using the first wire. In particular, implementing the plurality of conductors as three wires provides a relatively simple to engineer arrangement, for example where the three wires are to be passed along a wand of a “stick-vac” type vacuum cleaner, and may allow a relatively cheap and simple three-pin electrical connection between the main body and the cleaner head. Using the first wire for communications may enable half-duplex bidirectional communication between the main body and a cleaner head in a manner described in more detail below.

In certain embodiments, the cleaning appliance may be operable in each of two modes, wherein: in a first mode, three-phase AC power is delivered from the main body to a cleaner head using the three wires, and in a second mode, communications between the main body and the cleaner head may be performed using the first wire, and power may be delivered from the main body to a cleaner head using the remaining two wires. In this way, the cleaning appliance is adapted to work with a variety of cleaner heads having different power requirements and communications capabilities. For example, the cleaning appliance is configured deliver three-phase power to a cleaner head having a BLDC motor, or singlephase power to a cleaner head having a brushed motor or other DC load while also allowing communications with the cleaner head, e.g. for diagnostics and/or telemetry data to be communicated to the main body.

Optionally, the main body may comprise a speed controller for a direct current, DC, motor. For example, the main body may adjust an effective DC voltage applied to a DC motor through pulse-width modulation, PWM, control. This allows the cleaning appliance to be used with cleaner heads which include a DC motor. By providing the speed controller in the main body, the cleaner head itself may be simpler and less expensive to manufacture. In addition, by being provided in this way, the cleaning appliance may be more ergonomic, as the weight of the speed controller is provided in the main body, and not in the cleaner head itself as in known arrangements. In particular, for “stick- vac” type vacuum cleaners, the main body is held by a user (e.g. with a handle), whereas the cleaner head is at a distance from the main body, and so by concentrating more weight in the main body the cleaning appliance is easier to hold and manipulate. For example, the first conductor may be used to identify a nominal voltage of the DC motor. Speed control may be implemented using a sensorless control algorithm, for example, such as a ripple counting technique using the plurality of conductors.

In certain embodiments, the main body may comprise a switching circuit, for example a high side switch with bidirectional blocking capability, which is controllable by the controller to allow the first conductor to be switched between a higher voltage connection of the three-phase inverter for operating as a power line, and a separate lower voltage connection for operating as a communications channel. For example, the high voltage connection may be a voltage which is suitable to drive a BLDC motor, other motor type, or other components in a cleaner head, for example a connection between 12 V and 42 V,, such as 14 V, and the low voltage connection may be a voltage which is suitable for communications with the cleaner head, for example in a range of between 5 V and 1 .8 V or less, or a 3.3 V connection for example. In particular, the low voltage connection may be chosen to allow communications with a variety of cleaner heads. Advantageously, the controller may be configured to toggle the conductor between the low voltage connection and a ground connection to transmit data via the first conductor, for example according to a single-wire communications protocol as described in more detail below. Optionally, the main body may further comprise a memory accessible by the controller, wherein the memory stores data allowing the controller to determine a type of cleaner head connected to the main body based on at least one of a sensed voltage, a sensed current trend, and/or communications with an integrated circuit comprising an identification chip. By being provided with a memory in this way, the controller is able to identify a variety of cleaner heads according to methods described in more detail below.

Optionally, the cleaning appliance may further comprise a cleaner head, wherein the cleaner head is configured to receive power and/or communications data from the main body, and comprises at least one of: a resistor (which may be referred to herein as an identity resistor, as it allows identification of the cleaner head); an integrated circuit comprising an identification chip; and/or a motor. The cleaner head is thereby adapted to be operable with the main body as described above, and may be identifiable by the controller of the main body, for example based on a resistance of the resistor; by communicating with the integrated circuit; and/or by detecting a short circuit where the cleaner head comprises a motor such as a BLDC motor or brushed motor. This allows a variety of cleaner heads to be identified and, where appropriate, power delivered to the cleaner head from the main body. In certain embodiments the integrated circuit may be configured to transmit data to the main body via the first conductor, thereby allowing the cleaner head to send data such as telemetry and/or diagnostic data to the main body. Optionally, the integrated circuit may comprise a parasitic power supply configured to derive power from the first conductor. By being provided in this way, the cleaner head does not require its own power supply, such as a battery or the like, for powering the integrated circuit. This may make the cleaner head lighter, thereby improving the ergonomics of the cleaning appliance by making it easier for a user to operate and move in use.

According to a second aspect of the present invention, there is provided a control method for a cleaning appliance comprising a main body for connecting to a cleaner head, wherein the cleaning appliance comprises a plurality of conductors for conveying power from the main body to a cleaner head; and wherein the method comprises: enabling a first conductor of the plurality of conductors to operate as a communications channel between the main body and a cleaner head; sensing a voltage of the communications channel for identifying a cleaner head connected to the main body or detecting a fault; and responsive to said sensing, operating the first conductor as either: a power line for conveying power to the cleaner head, or a communications channel between the main body and the cleaner head. Generally, the method of the second aspect of the invention provides a more flexible means by which to identify a cleaner head which is connected to the main body, allowing cleaner heads which cannot be differentiated by known identification methods. By operating in accordance with this method, a cleaning appliance may identify a connected cleaner head (e.g., by detecting the resistance of an identity resistor or other component in the cleaner head as set out in more detail below) or identify that there is a fault if no cleaner head is connected, for example. Furthermore, the method provides that the first conductor may then be operated as a power line or as a communications channel based on the identified cleaner head. This allows the main body to be used with a variety of cleaner heads having differing requirements for power or communications as described herein.

Optionally, the cleaning appliance may comprise a three-phase inverter, and the plurality of conductors may comprise three wires such that the first conductor is a first wire of the three wires, and wherein the control method may further comprise: delivering three-phase alternating current, AC, power to the three wires, or performing communications using the first wire, and delivering power to the remaining two wires. In this way, operation of the cleaning appliance may be adjusted based on the determination of a connected cleaner head, and the method allows the cleaning appliance to work with a variety of cleaner heads having different power requirements and communications capabilities. For example, three-phase power may be delivered to a cleaner head having a BLDC motor, or single-phase power delivered to a cleaner head having a brushed motor or other DC load while also allowing communications with the cleaner head, e.g. for diagnostics and/or telemetry data to be communicated to the main body. Advantageously, the method may further comprise determining that the sensed voltage indicates a short circuit; responsive to the determination of a short circuit, operating the first conductor as a power line; and measuring a current trend through the plurality of conductors to identify a cleaner head connected to the main body. By determining that the sensed voltage indicates a short circuit, the method may identify that a connected cleaner head comprises one or more motors, and the current trend (e.g., increasing current, decreasing current, slew rate) through the plurality of conductors may be used to determine the characteristics of the one or more motors, for example.

Optionally, the method may further comprise determining that the sensed voltage indicates an open circuit; and responsive to the determination of an open circuit, operating the first conductor as a communications channel. By determining that the sensed voltage indicates an open circuit, the method may identify either that a connected cleaner head is able to identify itself via communications, or that there is no cleaner head attached. Identification of a cleaner head, or whether a cleaner head is present, may thereby be confirmed by operating the first conductor as a communications channel. For example, the communications channel may enable half-duplex bidirectional communication with a cleaner head as described herein.

Advantageously, the method may further comprise determining that the sensed voltage indicates neither of a short circuit or an open circuit; responsive to the determination of neither of a short circuit or an open circuit, operating the first conductor as a power line; and measuring a current trend through the plurality of conductors to identify a cleaner head connected to the main body. By determining that the sensed voltage indicates neither an open circuit nor a short circuit, the method may identify a connected cleaner head through a sensed voltage (e.g., indicating a resistance of an identification resistor within the cleaner head), and the method may go on to determine a cleaner head (e.g., whether the cleaner head comprises additional components, such as a PCB) by measuring a current trend through the plurality of conductors. For example, the sensed voltage may fall within a predetermined range, within which the voltage may indicate a short circuit, an open circuit, or a connected identification resistor in a cleaner head, and if the sensed voltage is outside of this predetermined range (e.g., a negative voltage) then the sensed voltage may be indicative of a fault within the cleaning appliance.

According to a third aspect of the present invention, there is provided a cleaning appliance in accordance with the first aspect of the present invention, wherein the main body comprises a memory device storing instructions which, when executed, cause the controller to perform a control method in accordance with the second aspect of the present invention.

The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. Summary of the Figures

Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

Fig. 1 is a perspective view of a cleaning appliance according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of a cleaning appliance according to an embodiment of the present invention;

Fig. 3 is a schematic diagram of a three-phase inverter circuit which may be used in a cleaning appliance according to embodiments of the present invention;

Figs. 4a-4f are schematic diagrams of cleaner heads which may be used with a cleaning appliance according to embodiments of the present invention;

Fig. 5 is a flow diagram showing a control method for a cleaning appliance according to an embodiment of the present invention; and

Fig. 6 is an example decision tree for a control method according to an embodiment of the present invention.

Detailed Description of the Invention

Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

Fig. 1 shows a perspective view of a cleaning appliance according to an embodiment of the present invention. In particular, the cleaning appliance is a vacuum cleaner 2. The vacuum cleaner 2 of this embodiment is a “stick-vac” type vacuum cleaner. That is, it has a cleaner head 4 which can be connected to a main body 6 by a generally tubular elongate wand 8. The cleaner head 4 is also connectable directly to the main body 6 to transform the vacuum cleaner 2 into a handheld vacuum cleaner.

The main body 6 comprises a dirt separator 10 which in this case is a cyclonic separator. The cyclonic separator has a first cyclone stage 12 comprising a single cyclone, and a second cyclone stage 14 comprising a plurality of cyclones 16 arranged in parallel. The main body 6 also has a removable filter assembly 18 provided with vents 20 through which air can be exhausted from the vacuum cleaner 2. In this case the main body 6 of the vacuum cleaner 2 has a pistol grip 22 positioned to be held by the user. At an upper end of the pistol grip 22 is an on/off switch in the form of a trigger (not visible) which must be held (i.e. 'pulled') in order to keep the vacuum cleaner turned on. As soon as the user releases the trigger, the vacuum cleaner is turned off. Positioned beneath a lower end of the pistol grip 22 is a battery pack 26 which comprises a plurality of rechargeable cells (not visible). A controller in the form of a PCB (not visible), and a vacuum motor (not visible) comprising a fan driven by an electric motor are provided in the main body 6 behind the dirt separator 10. It will be appreciated that a number of different cleaner heads may be connected to the main body 6, either directly or via the wand 8. Each cleaner head may comprise different components (e.g., motors, lights) and so have different power and/or communications requirements. The vacuum cleaner 2 is therefore configured to be able to identify a connected cleaner head and enable power and/or communications to the cleaner head as set out below.

Fig. 2 is a schematic diagram of a cleaning appliance 30 according to an embodiment of the present invention. For example, the cleaning appliance 30 may be a vacuum cleaner as discussed above with respect to Fig. 1 .

The cleaning appliance 30 comprises a main body 32, the main body comprising a controller 321 , and a plurality of conductors 34 for conveying power from the main body 32 to a cleaner head 36. A number of different cleaner heads may be used with the cleaning appliance 30, each cleaner head being adapted to perform a different task. For example, cleaner heads may differ by shape, configuration, or components for cleaning different areas of surfaces. There is therefore a need for the cleaning appliance 30 to be able to identify which cleaner head is connected to the main body 32.

As described above, the cleaner head 36 can be connected to the main body 32 by a generally tubular elongate wand, or can be connectable directly to the main body 32. The plurality of conductors 34 are provided as three wires, and a first wire 34a is switchable by the controller 321 to operate as each of a power line for conveying power to the cleaner head 36, and a communications channel between the main body 32 and the cleaner head 36, for example by a means set out in more detail below. The plurality of conductors 34 may pass through the elongate wand, for example, and corresponding connectors on each of the main body 32, elongate wand, and cleaner head 36 allow an electrical connection to be made via the conductors 34.

The main body 32 further comprises a three-phase inverter 322 connected to deliver three-phase AC power to the plurality of conductors 34, controlled by the controller 321 . Although not shown, the main body 32 may comprise a power supply, e.g., a battery, for delivering energy to the three-phase inverter 322. The three-phase inverter 322 may also be controlled to deliver power to two of the plurality of conductors 34, while the first wire 34a is used for communications between the main body 32 and the cleaner head 36. A switching circuit 323 is also present within the main body 32, controllable by the controller 321 to allow the first wire 34a to be switched between a higher voltage connection of the three- phase inverter 322 for operating as a power line, and a separate lower voltage connection for operating as a communications channel.

The main body 32 comprises a memory 324 accessible by the controller 321 , wherein the memory 324 stores data allowing the controller to 321 determine a type of cleaner head 36 connected to the main body 32 based on at least one of a sensed voltage, and/or communications with an integrated circuit comprising an identification chip. The memory 324 also stores instructions which, when executed, cause the controller 321 to perform a control method as described below, allowing the controller 321 to identify a cleaner head 36.

The cleaner head 36 is configured to receive power and/or communications data from the main body 32 via the plurality of conductors 34. The cleaner head 36 comprises a number of components which enable the controller 321 to identify the cleaner head 36, and it will be appreciated that different cleaner heads may comprise any one or more of these components, for example depending upon the task which the cleaner head is adapted to be used for. An identification resistor 361 is provided in the cleaner head, allowing identification of the cleaner head 36 based on a detected resistance provided by the resistor 361 . For example, the controller 321 may detect a resistance through the plurality of conductors 34 and look up a corresponding resistance value in the memory 324 to identify the cleaner head 36. In some embodiments, a cleaner head may comprise no other active components, and may be referred to as a “passive tool” or “passive cleaner head”.

The cleaner head 36 further comprises a motor 362. In some embodiments, this may be a brushless DC motor, which may be powered by three-phase AC power delivered via the plurality of conductors 34, for example. However, in the embodiments of Fig. 2, the motor 362 is a brushed motor powered by DC power delivered via two of the plurality of conductors 34, such that the first wire 34a may be used as a communications channel. It will be appreciated that, in some embodiments, the cleaner head 36 may comprise multiple motors. The motor 362 may drive a rotating agitator or brush bar within the cleaner head 36, for example, which may agitate dirt or other particles from a surface to be entrained in an air flow and delivered through the cleaner head 36 to the main body 30. Of course, it will be appreciated that the motor 362 may drive any suitable other component in the cleaner head 36. To identify the cleaner head 36, the controller 324 may detect a current trend through the plurality of conductors 34, as set out in more detail below, and look up a corresponding current trend in the memory 324 to identify the cleaner head 35.

The cleaner head 36 also comprises an integrated circuit (IC) 363 which is powered by a parasitic power supply 364 deriving power from the plurality of conductors 34, and in particular from the first wire 34a. The IC 363 comprises an identification chip which may communicate with the controller 321 via the first wire 34a and so identify the cleaner head 36 to the controller 321 . The IC 363 may also communicate with the controller 321 while the cleaning appliance 30 is in use, for example to send telemetry or other data to the controller 321 . Such data may be communicated to a user, by a screen or other display means on the main body 32, for example.

Fig. 3 shows a schematic diagram of a three-phase inverter circuit 40 which may be present in a cleaning appliance, for example within the main body 6 of the vacuum cleaner 2 as discussed above with respect to Fig. 1 , or the main body 32 described with respect to Fig. 2. The three-phase inverter circuit 40 comprises a plurality of conductors in the form of three wires W, U, V, which can be used to deliver power to and/or communicate with a cleaner head which may be connected to the main body. In particular, in a first mode, three-phase AC current may be delivered using each of the three wires W, U, V by activating the transistors S1-S6 in the appropriate sequence to deliver three-phase power to a BLDC motor of the cleaner head. In a second mode, communications between the main body and a cleaner head may be performed using a first wire W, and power may be delivered to the cleaner head using the remaining two wires U, V. For example, in embodiments where the cleaner head comprises a DC motor, wire U may be used as a power line (e.g., a DC voltage which pulse-width modulation for speed control) and wire V may be used as the return line for ground. The wire V may also be used as a ground return line for a communications signal on the first wire W (e.g., such that all components in the cleaner head may be referenced to a single electrical ground). For example, the inverter circuit 40 may be operated by a controller within the main body of the cleaning appliance. The plurality of conductors and the inverter circuit 40 are also used to identify a cleaner head by operating according to a control method set out in more detail below. To enable the first wire Wto act as each of a power line for conveying power to the cleaner head and a communications channel between the main body and the cleaner head, a switching circuit 42 is provided as part of the inverter circuit 40. The switching circuit 42 is controllable (e.g., by the controller) to allow the first wire Wto be switched between a higher voltage connection (Vdc, which may be a 12V connection, for example) and a lower voltage connection (3V3) for operating as a communications channel. Switching between the higher and lower voltage connections may be controlled by the controller, by toggling the enable signal EN off or on. When the enable signal EN is on, such that the switching circuit 42 is connected to the lower voltage connection (3V3), transistor S1 is turned off to ensure that a high current does not flow into the first wire W, which may damage components (e.g., an integrated circuit) on the cleaner head. The switching circuit 42 is also operable to toggle the first wire W between the low voltage connection (3V3) and a ground connection in order to transmit data via the first wire W, and this is done by toggling a transmission signal line Tx which selectively activates transistor S2. Since communications is carried out only on the first wire W, the first wire W must be shared for up-link and down-link, and so communications are half-duplex, initiated by the controller in the main body, with communications being received at the main body from the cleaner head on the received signal line Rx. For example, communications may take place using the 1-Wire® communications protocol, or a similar communications protocol such as Single Wire by Microchip or SDQ by Texas Instruments, with wire V grounded by transistor S6 to provide a ground return connection for communications.

The switching circuit 42 comprises a pull-up resistor (Rpu), the resistance value of which is chosen to be low enough to be able to source current into parasitic power supplies in a cleaner head (see below) electrically connected to the first wire W. For example, the pull-up resistor may have a value of 470 Q. The inverter circuit, and switching circuit 42, may also be operated to aid in identification of a connected cleaner head, according to a method set out in more detail below. In particular, a current through the plurality of conductors may be detected by Isense, and the current trend may be used to help identify a cleaner head.

Figs. 4a-4f show schematic drawings of a number of cleaner heads 50a-50f which may be used with embodiments of the present invention. Each cleaner head 50a-50f has a different arrangement of components which, as well as performing other functions (e.g., powering agitator brushes or the like), allow each cleaner head 50a-50f to be identified by a controller following a control method discussed herein. It will be appreciated that other arrangements of cleaner heads are possible, and the cleaner heads 50a-50f are described merely as possible examples. Each of the cleaner heads 50a-50f comprises a connector 51 for connecting to a main body of a cleaning appliance, for example directly or via an elongate wand as described above. Each of the cleaner heads 50a-50f also comprises three wires a, b, c which are configured to be electrically connected, via the connector 51 , to a plurality of conductors from the main body. For example, the three wires a, b, c may be electrically connected to wires W, U, V of the inverter circuit 40, respectively, as described above with respect to Fig. 3, allowing power and/or communications to be delivered from the main body to the cleaner head 50a-50f.

A first cleaner head 50a comprises an identification resistor 52, which is connected between a first wire a and a third wire c. The controller in the main body may thereby identify the cleaner head 50a by determining the resistance value of the identification resistor 52.

A second cleaner head 50b comprises a PCB 53, and is similar to the first cleaner head 50b in that the second cleaner head 50b also comprises an identification resistor 52 connected between the first wire a and the third wire c. The cleaner head 50b also comprises an RC circuit 54 which may be used to provide an additional means for cleaner head identification by a main body, the RC circuit 54 being connected between the second wire b and the third wire c. In this way, a main body may identify the cleaner head 50b using the communications channel (i.e., along the first wire a), and may deliver power on the other two wires (i.e., the second wire b and the third wire c).

In some embodiments, the first cleaner head 50a and the second cleaner head 50b may each have a unique identification resistor 52, and so they may be identified by a main body based only on the resistance value. Alternatively, in other embodiments, the first cleaner head 50a and the second cleaner head 50b may each have a similar identification resistor 52 with the same resistance, and a main body may differentiate the second cleaner head 50b by sensing the current on the second wire b and the third wire c to detect the RC circuit 54. For example, in some examples a cleaner head such as the second cleaner head 50b may comprise a motor, or in other examples may comprise a DC load (e.g., an LED), and these examples may have different RC circuits 54 to enable a main body to identify their different power requirements. By also providing an RC circuit 54 in this way, a larger number of unique cleaner heads may therefore be identifiable according to the methods set out herein.

A third cleaner head 50c also comprises an identification resistor 52 connected between the first wire a and the third wire c. The cleaner head 50c further comprises a motor 56, which may be a brushed DC motor for example. A controller in a connected main body may identify the cleaner head 50c by the resistance of the identity resistor 52, and confirm the presence and type of motor 56 by sensing a current trend through the plurality of conductors, in particular between the second wire b and the third wire c. The controller may then determine operating parameters accordingly and perform control of the motor 56. A fourth cleaner head 50d includes an integrated circuit 57 which is configured to communicate with a main body, for example using the 1-Wire® communications protocol along the first wire a. The cleaner head 50d may thereby communicate with a main body and identify itself. The cleaner head 50d also comprises a controller 58 which is configured to control various components of the cleaner head 50d, such as motor 55 and LEDs 59. The cleaner head 50d may comprise a parasitic power supply (not shown) to provide power to the integrated circuit 57 from the first wire a.

A fifth cleaner head 50e comprises a brushless DC (BLDC) motor 60 which is electrically connected to each of the three wires a, b, c so as to receive three-phase AC power from a main body. In this way, the cleaner head 50e may be lighter than known cleaner heads containing BLDC motors, as a three-phase inverter may be located within the main body, for example as described above with respect to Figs. 2 and 3. A controller within a main body may be able to determine that the cleaner head 50e is connected by sensing a current trend through the plurality of conductors connected to the three wires a, b, c, for example according to a method as described herein.

A sixth cleaner head 50f comprises two motors 61 , 62. A first motor 61 is connected between the first wire a and the second wire b. A second motor is connected between the second wire b and the third wire c. In this way, the motors 61 , 62 may be supplied with power and controlled from a main body delivering power through the plurality of conductors connected to the three wires a, b, c. A controller within a main body may be able to determine that the cleaner head 50f is connected by sensing a current trend through the plurality of conductors connected to the three wires a, b, c, for example according to a method as described herein. Fig. 5 is a flow diagram showing a control method 500 for a cleaning appliance according to an embodiment of the present invention. In particular, the controller method 500 may be applied using an inverter circuit according to Fig. 3, for example in a cleaning appliance as described above with respect to Figs. 1 and 2, e.g., to identify a cleaner head such as the cleaner heads 50a-50f described with respect to Figs. 4a-4f. It will, however, be understood that the method described may not be limited to such arrangements.

In a first step 501 , the cleaning appliance is initialized, and the communications channel is enabled 502. For example, in the inverter circuit 40, the switching circuit 42 is controlled so as to connect the first wire Wto the lower voltage connection to enable communications with a cleaner head. Initialising the cleaning appliance may include enabling the pull up resistor Rpu and recalling calibration data, such as voltage thresholds, from a memory device (e.g., memory 324).

The method then checks for a tool, with a ground reference enabled (e.g. by switching transistor S6 on), by sensing a voltage of the communications channel in step 503, for example through the received signal line Rx. This voltage check will result in one of three outcomes: either a short circuit is detected at step 504, or an open circuit is detected at step 508, or neither a short nor an open circuit is detected at step 510. These situations will be discussed below in turn.

If the sensed voltage indicates a short circuit 504, this is indicative that the cleaner head comprises a BLDC motor or two brushed motors connected between the first wire W and wire V, as their windings typically have a series resistance below 1 Q. To accurately identify the cleaner head present, the power line is enabled at step 505, e.g., by switching the first wire W from the lower voltage to the higher voltage connection via the switching circuit 42. A current trend is measured at step 506. This is done, for example, by sending current pulses along the plurality of conductors (e.g. by activating transistors S3 and S6 for a short period, then by activating transistors S2 and S3 for a short period), and measuring the sensed current flow (e.g. at Isense). The slew rate of the current between successive pulses on the plurality of conductors is compared to identify a motor type at step 507. For example, if the current trend is increasing, and the slew rate in a second pulse is slower than a first pulse then it is identified that the cleaner head comprises two brushed motors (e.g., as cleaner head 50f shown in Fig. 4f). If the current trend is increasing, and the slew rates between successive pulses are similar, then it is identified that the cleaner head comprises a BLDC as the detected motor windings are symmetrical (e.g., as the cleaner head 50e shown in Fig. 4e).

If the sensed voltage indicates an open circuit 508, then it may be determined that either than connected cleaner head can identify itself through the single-wire communications protocol (e.g., as the cleaner head 50d shown in Fig. 4d), or there is no cleaner head attached. In this situation, the cleaner head ID is checked at step 509. This may identify the connected cleaner head, or, if no communication is possible, identify that no cleaner head is connected or that the cleaner head may have a fault.

If the sensed voltage indicates neither of a short circuit nor an open circuit 510, then it is identified that the cleaner head comprises an identification resistor, and so the cleaner head may be identified based on the sensed voltage (i.e., by determining the resistance of the identification resistor) at step 511 . For example, this may identify a cleaner head as the cleaner head 50a shown in Fig. 4a or the cleaner head 50c shown in Fig. 4c. Further identification (e.g. to further identify the cleaner head type and any further components of the cleaner head) may be carried out by current measurements; for example to identify an RC circuit within the cleaner head as discussed above with respect to Fig. 4b. To do so, at step 512 the power line is enabled, and a current trend is measured at step 513. This is done, for example, by sending current pulses along the plurality of conductors (e.g. by activating transistors S3 and S6 for a short period, then by activating transistors S2 and S3 for a short period), and measuring the sensed current flow (e.g. at Isense). If the current trend is stable or goes down, the cleaner tool is identified as comprising a PCB (e.g., as the cleaner head 50b shown in Fig. 4b).

If an unexpected voltage is sensed at step 503 (e.g. a negative voltage, or a voltage higher than the low voltage of the communications channel), then it may be indicative of a fault within the cleaning appliance. It will be appreciated that the first conductor of the plurality of conductors may be operated as either a communications line or a power line in response to the identification of a connected cleaner head, in accordance with the requirements of the cleaner head.

Fig. 6 is an example decision tree 600 for a control method according to an embodiment of the present invention. In particular, the decision tree 600 may be applied using an inverter circuit according to Fig. 3, for example in a cleaning appliance as described above with respect to Figs. 1 and 2, e.g., to identify a cleaner head such as the cleaner heads 50a-50f described with respect to Figs. 4a-4f. It will, however, be understood that the method described may not be limited to such arrangements.

In a first step 601 , the cleaning appliance is initialized, and a communications channel is enabled. For example, in the inverter circuit 40, the switching circuit 42 is controlled so as to connect the first wire Wto the lower voltage connection to enable communications with a cleaner head. Initialising the cleaning appliance may include enabling the pull up resistor Rpu and recalling calibration data, such as voltage thresholds, from a memory device (e.g., memory 324).

A voltage of the communications channel is then sensed at step 602. In particular, the voltage on a first conductor of the plurality of conductors (e.g., wire W) may be sensed, as Vpu, and compared with a lower threshold voltage VthOv. If the sensed voltage, Vpu, is less than or equal to the lower threshold, VthOv, then a short circuit is detected and processing moves on to step 603. If, however, the sensed voltage, Vpu, is greater than the threshold, VthOv, then a further comparison is made with an upper threshold voltage, VpuO, at step 604.

After determining that the sensed voltage indicates a short circuit at steps 602 and 603, sequential current pulses are passed through each of the plurality of conductors at step 605 and the current trend is measured, as discussed above with respect to Fig. 5. In this way, the method may determine, for example, that the cleaner head comprises a BLDC 605a, or that the cleaner head comprises more than one motor 605b. The current pulses and the current trend may also indicate if there is an error in the cleaner head 605c, which may be confirmed to a user, for example by a display means on a main body. The upper threshold voltage, VpuO, is chosen such that if the sensed voltage, Vpu, is greater than this threshold then the voltage is indicative of an open circuit, such that it may be determined that either than connected cleaner head can identify itself through the single-wire communications protocol (e.g., as the cleaner head 50d shown in Fig. 4d), or there is no cleaner head attached. In this situation, processing moves on to steps 606 and 607. At step 607, a communications channel is enabled, and communications initiated. If a valid response is received, then it may be identified that a cleaner head is connected, and the type of cleaner head may be confirmed via the communications channel 607a. If in invalid response or no response is received then this may indicate an error or that no tool is connected 607b. This result may be confirmed to a user, for example by a display means on a main body. If the sensed voltage, Vpu, is neither an open circuit nor a short circuit, and falls between the lower threshold, VthOv, and the upper threshold, VpuO, then it is identified that the cleaner head comprises an identification resistor (step 608). The value of the sensed voltage, Vpu, may be used to identify the connected cleaner head directly, or a current pulse may be sent through the plurality of conductors to identify other components which may be present in the cleaner head, at step 609. The current pulse may, for example, determine that no other components are present in the cleaner head (such a cleaner head may be referred to as a ‘passive tool’) 609a, determine that the cleaner head comprises a single brushed motor 609b, and/or determine that the cleaner head comprises a simple PCB 609c.

If an unexpected voltage is sensed at steps 602 and/or 604 (e.g. a negative voltage, or a voltage higher than the low voltage of the communications channel, a voltage falling outside of the range set by VthOv and VpuO), then it may be indicative of a fault within the cleaning appliance.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example +/- 10%.

Claims

Claims:

1 . A cleaning appliance comprising: a main body for connecting to a cleaner head, the main body comprising a controller, and a plurality of conductors for conveying power from the main body to a cleaner head, wherein the plurality of conductors comprises a first conductor which is switchable by the controller to operate as each of: a power line for conveying power to the cleaner head, and a communications channel between the main body and the cleaner head.

2. A cleaning appliance according to claim 1 , wherein the main body comprises a three-phase inverter connected to deliver three-phase alternating current, AC, power to the plurality of conductors.

3. A cleaning appliance according to claim 2, wherein the plurality of conductors comprises three wires, and the first conductor which is switchable by the controller is a first wire of the three wires.

4. A cleaning appliance according to claim 3, wherein the cleaning appliance is operable in each of two modes, wherein: in a first mode, three-phase AC power is delivered from the main body to a cleaner head using the three wires, and in a second mode, communications between the main body and the cleaner head is performed using the first wire, and power is delivered from the main body to a cleaner head using the remaining two wires.

5. A cleaning appliance according to any one of claims 2 to 4, wherein the main body comprises a speed controller for a direct current, DC, motor.

6. A cleaning appliance according to any one of claims 2 to 5, wherein the main body comprises a switching circuit which is controllable by the controller to allow the first conductor to be switched between a higher voltage connection of the three-phase inverter for operating as a power line, and a separate lower voltage connection for operating as a communications channel.

7. A cleaning appliance according to claim 6, wherein the controller is configured to toggle the conductor between the low voltage connection and a ground connection to transmit data via the first conductor.

8. A cleaning appliance according to any one of the preceding claims, wherein the main body comprises a memory accessible by the controller, wherein the memory stores data allowing the controller to determine a type of cleaner head connected to the main body based on at least one of a sensed voltage, a sensed current trend, and/or communications with an integrated circuit comprising an identification chip.

9. A cleaning appliance according to any one of the preceding claims, further comprising a cleaner head, wherein the cleaner head is configured to receive power and/or communications data from the main body, and comprises at least one of: a resistor; an integrated circuit comprising an identification chip; and/or a motor.

10. A cleaning appliance according to claim 9, wherein the integrated circuit is configured to transmit data to the main body via the first conductor.

11 . A cleaning appliance according to claim 9 or claim 10, wherein the integrated circuit comprises a parasitic power supply configured to derive power from the first conductor.

12. A control method for a cleaning appliance comprising a main body for connecting to a cleaner head, wherein the cleaning appliance comprises a plurality of conductors for conveying power from the main body to a cleaner head; and wherein the method comprises: enabling a first conductor of the plurality of conductors to operate as a communications channel between the main body and a cleaner head; sensing a voltage of the communications channel for identifying a cleaner head connected to the main body or detecting a fault; and responsive to said sensing, operating the first conductor as either: a power line for conveying power to the cleaner head, or a communications channel between the main body and the cleaner head.

13. A control method according to claim 12, wherein the cleaning appliance comprises a three-phase inverter, and the plurality of conductors comprises three wires such that the first conductor is a first wire of the three wires, and wherein the control method further comprises: delivering three-phase alternating current, AC, power to the three wires, or performing communications using the first wire, and delivering power to the remaining two wires.

14. A control method according to claim 12 or claim 13, further comprising: determining that the sensed voltage indicates a short circuit; responsive to the determination of a short circuit, operating the first conductor as a power line; and measuring a current trend through the plurality of conductors to identify a cleaner head connected to the main body.

15. A control method according to claim 12 or claim 13, further comprising: determining that the sensed voltage indicates an open circuit; and responsive to the determination of an open circuit, operating the first conductor as a communications channel.

16. A control method according to claim 12 or claim 13, further comprising: determining that the sensed voltage indicates neither of a short circuit or an open circuit; responsive to the determination of neither of a short circuit or an open circuit, operating the first conductor as a power line; and measuring a current through the plurality of conductors to identify a cleaner head connected to the main body.

17. A cleaning appliance according to any one of claims 1 to 11 , wherein the main body comprises a memory device storing instructions which, when executed, cause the controller to perform a control method according to any one of claims 12 to 16.