FIELD OF THU INVENTION

The present invention relates to a pump assembly, and to a treatment appliance which includes a pump assembly. The treatment appliance is preferably a handheld treatment appliance, and is preferably a surface treating appliance. In preferred embodiments of the invention, the appliance is a dental treatment appliance. In a preferred embodiment, the appliance is an electric toothbrush having a fluid delivery system for delivering a fluid to the oral cavity of the user. This fluid may be toothpaste, or a fluid for improved interproximal cleaning. Alternatively, the appliance may not include any bristles or other elements for brushing teeth, and may be in the form of a dedicated interproximal treatment appliance.

BACKGROUND OF THE INVENTION

Electric toothbrushes generally comprise a tool which is connected to a handle. The tool comprises a stem and a brush head bearing bristles for brushing teeth. The brush head comprises a static section which is connected to the stem, and at least one moveable section which is moveable relative to the static section, for example with one of a reciprocating, oscillating, vibrating, pivoting or rotating motion, to impart a brushing movement to bristles mounted thereon. The stem houses a drive shaft which couples with a transmission unit within the handle. The transmission unit is in turn connected to a motor, which is driven by a battery housed within the handle. The drive shaft and the transmission unit convert rotary or vibratory motion of the motor into the desired movement of the moveable section of the brush head relative to the static section of the brush head.

It is known to incorporate into an electric toothbrush a fluid delivery system for generating a burst of working fluid for interproximal cleaning. For example, WO2018/055329 describes a toothbrush having a handle and a brush head which includes a nozzle from which working fluid is delivered to the oral cavity of the user. A pump assembly draws fluid from a fluid reservoir, and urges working fluid towards the nozzle to deliver a burst of working fluid to the teeth of the user. The pump assembly comprises a positive displacement pump and a drive for actuating the pump. The pump comprises a piston which is moveable relative to a pump housing to draw fluid into a fluid chamber of the pump, and to subsequently eject fluid from the fluid chamber.

Coupling members connect the pump to the drive. A first coupling member is in the form of a drum which is rotated by a motor of the drive. The drum comprises a pair of diametrically opposed pins. A second coupling member comprises an arm which is connected to the piston, and which comprises a seat for receiving one of the pins of the drum. When a first pin is received by the seat, the pump is connected to the drive so that with rotation of the drum the piston moves backwards to draw fluid into the fluid chamber. As fluid is drawn into the fluid chamber, a spring is compressed by the moving piston. The pump is held in a“primed” configuration until the user presses a button, which initiates further rotation of the drum. As the drum rotates, the second pin engages the arm to release the first pin from the seat, and so decouple the pump from the drive. Upon decoupling of the pump from the drive, the spring expands and pushes the piston forwards to urge a burst of working fluid from the pump. As the piston moves forwards, the arm moves with the piston so that the second pin enters the seat to re- couple the pump to the drive.

SUMMARY OF THU INVENTION

In a first aspect, the present invention provides a pump assembly for a dental treatment appliance, the pump assembly comprising:

a positive displacement pump comprising a fluid chamber having a fluid inlet connectable to a source of fluid, and a fluid outlet;

a drive for actuating the pump to draw fluid into the fluid chamber through the fluid inlet;

an energy storage device for converting kinetic energy generated during actuation of the pump by the drive into potential energy, and storing the potential energy; and a freewheel clutch comprising a rotatable input section which is connected to the drive, and a rotatable output section which is connected to the pump;

wherein, with rotation of the input section by the drive, the clutch sequentially adopts a coupled state, in which the output section rotates with the input section so that the pump is actuated by the drive to draw fluid into the fluid chamber, and a freewheeling state, in which the output section becomes rotatable relative to the input section to enable the energy storage device to use stored potential energy to actuate the pump to urge fluid from the fluid chamber through the fluid outlet.

The use of a freewheel clutch which can switch between coupled and freewheeling states to sequentially drawn fluid into the fluid chamber and expel fluid from that chamber can provide a compact pump assembly which can reliably switch between the different states of the clutch.

Preferably, the pump comprises a fluid displacement member which is moveable relative to the fluid chamber to draw fluid into the fluid chamber. This fluid displacement member is connected to the output section of the clutch. The fluid displacement member is preferably moveable along a linear path relative to the fluid chamber. In a preferred embodiment, the positive displacement pump is in the form of a piston pump, in which the fluid displacement member is a piston which is reciprocally movable within the fluid chamber to draw fluid into the fluid chamber and to subsequently urge that fluid from the fluid chamber.

The energy storage device is preferably in the form of a spring, but alternatively it may be in the form of an accumulator. The energy storage device is preferably arranged to engage the fluid displacement member. When the energy storage device is in the form of a spring, the spring becomes compressed as the fluid displacement member moves relative to the fluid chamber to draw fluid into the chamber. When the clutch adopts its freewheeling state, the spring rapidly expands and urges movement of the fluid displacement member in a reverse direction to urge fluid from the fluid chamber. The clutch preferably adopts sequentially the coupled state and the freewheeling state under the action of the energy storage device. The energy storage device is preferably in the form of a compression spring which is compressed as fluid is drawn into the fluid chamber to store potential energy. Under the force of the compressed spring, the output section is first urged to rotate in a first angular direction. The input section is rotated by the drive in a second angular direction opposite to the first angular direction, and so the clutch is first placed in its coupled state so that the output section rotates with the input section, under the action of the drive, in the second angular direction. The clutch remains in its coupled state until the output section reaches an angular position from which the force of the compressed spring urges the output section to rotate in the second angular direction. This places the clutch in its freewheeling state, in which the output section becomes rotatable, in the second angular direction, relative to the input section to enable the energy storage device to use stored potential energy to actuate the pump to urge fluid from the fluid chamber through the fluid outlet.

The output section preferably rotates about an axis which is orthogonal to the linear path. Preferably, the input member comprises an outer ring of the clutch, and the output member comprises an inner member of the clutch, the outer ring and the inner member being rotatable about a common axis. The drive preferably comprises a motor and a gear, preferably a worm gear, for engaging the output section to connect the output section to the motor. The motor preferably comprises a drive shaft which is connected to the gear, and is rotatable about an axis which is orthogonal to the rotational axis of the output section. The drive is preferably arranged so that the axis of the drive shaft is parallel to the linear path of the fluid displacement member. This can provide a compact arrangement of the pump assembly.

As mentioned above, the energy storage member preferably applies a force to the fluid displacement member which, during the coupled state of the clutch, urges the output section to rotate in a first angular direction and, during the freewheeling state of the clutch, urges the output section to rotate in a second angular direction opposite to the first angular direction. In the coupled state, the output section is rotatable from a first angular position to a second angular position, and, in the freewheeling state, the output section moves from the second angular position back to the first angular position. The second angular position is preferably 180° from the first angular position.

The output section is preferably connected to the fluid displacement member by a flexible tether. The pump assembly preferably comprises a pulley for guiding movement of the tether as the fluid displacement member moves relative to the fluid chamber.

In a second aspect the present invention provides a dental treatment appliance comprising:

a handle;

a fluid reservoir for storing a working fluid; and

a fluid delivery system for receiving working fluid from the fluid reservoir, and for delivering working fluid to the oral cavity of a user;

wherein the fluid delivery system comprises a pump assembly as aforementioned.

Features described above in connection with the first aspect of the invention are equally applicable to the second aspect of the invention, and vice versa.

BRIEF DE SCRIPTT ON OF THE DRAWINGS

Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1(a) is a perspective view, from the front, of a dental treatment appliance, and Figure 1(b) is a perspective view, from the rear, of the appliance;

Figure 2 is a schematic illustration of a fluid delivery system of the appliance; Figure 3 is an exploded view of a pump assembly of the fluid delivery system;

Figure 4(a) is a perspective view of the pump assembly as a clutch transitions from a freewheeling state to a coupled state, Figure 4(b) is a side view of the pump assembly of Figure 4(a), and Figure 4(c) is a sectional view taken along line A-A in Figure 4(b);

Figure 5(a) is a perspective view of the pump assembly during the coupled state of the clutch, Figure 5(b) is a side view of the pump assembly of Figure 5(a), and Figure 5(c) is a sectional view taken along line A-A in Figure 5(b);

Figure 6(a) is a perspective view of the pump assembly as the clutch transitions from the coupled state to the freewheeling state, Figure 6(b) is a side view of the pump assembly of Figure 6(a), and Figure 6(c) is a sectional view taken along line A-A in Figure 6(b); and

Figure 7(a) is a perspective view of the pump assembly during the freewheeling state of the clutch, Figure 7(b) is a side view of the pump assembly of Figure 7(a), and Figure 7(c) is a sectional view taken along line A-A in Figure 7(b).

DFTATT ED DESCRIPTION OF THE IW M I

Figures 1(a) and 1(b) illustrate external views of an embodiment of a dental treatment appliance 10. In this embodiment, the appliance is in the form of a handheld appliance, which is in the form of an electric toothbrush having an integrated assembly for dispensing a working fluid for improved interproximal cleaning.

The appliance 10 comprises a handle 12 and a cleaning tool 14. The handle 12 comprises an external body 16 which is preferably formed from plastics material. The body 16 is generally cylindrical in shape. The handle 12 comprises a user interface. The user interface comprises a user operable button 18 which is located within an aperture formed in the body 16 so as to be depressible by the thumb of a hand which is gripping the body 16 of the handle 12. Optionally, the handle 12 may comprise a display which is positioned so as to be visible to a user during use of the appliance. The appliance 10 may be connectable to a remote display, such as a display of a personal device or mobile telephone, to enable the user to select operating modes or parameters for the appliance 10 using the button 18 and/or the remote display, as described in more detail below.

The cleaning tool 14 comprises a stem 20 and a head 22. The stem 20 is elongate in shape, which serves to space the head 22 from the handle 12 to facilitate user operability of the appliance 10. In this embodiment, the head 22 of the cleaning tool 14 comprises a brush unit 24, which comprises a bristle carrier 26 and a plurality of sets of bristles 28 mounted on the bristle carrier 26. In this embodiment, the brush unit 24 is rigidly connected to the stem 20. However, in other embodiments the cleaning tool 14 may be provided without a brush unit 24 so that the appliance is in the form of a dedicated oral treatment appliance, for example for cleaning between the gaps in the user’s teeth, or for delivering a cleaning or whitening fluid to the teeth of the user.

With reference also to Figure 2, the appliance 10 also comprises a fluid reservoir 30 for storing a working fluid, and a nozzle 32 for delivering working fluid to the oral cavity of the user during use of the appliance 10. The working fluid is preferably a liquid working fluid, and in this embodiment is water. The fluid reservoir 30 is mounted on the handle 12 so as to extend about an end of the handle 12. The nozzle 32 is mounted on the head 22 of the cleaning tool 14. In this embodiment which includes a brush unit 24, the bristles 28 are arranged around the nozzle 32.

The nozzle 32 forms part of a fluid delivery system 34 for receiving working fluid from the fluid reservoir 30 and for delivering bursts of working fluid to the oral cavity of a user during use of the appliance 10. Each burst of working fluid preferably has a volume which is less than 1 ml, more preferably less than 0.5 ml. The fluid delivery system 34 is illustrated schematically in Figure 3. In overview, the tip of the nozzle 32 comprises a fluid outlet 35 through which a burst of working fluid is delivered to the oral cavity of the user. The fluid delivery system 34 comprises a fluid inlet 36 for receiving working fluid from the fluid reservoir 30. In this embodiment, the working fluid is a liquid working fluid, which is preferably water. The fluid inlet 36 is positioned on the handle 12, preferably on the end of the body 16 of the handle 12, and is arranged to connect to a fluid port of the fluid reservoir 30 when the fluid reservoir 30 is connected to the handle 12. The cleaning tool 14 is detachable from the handle 12, and the fluid reservoir 30 can be pulled away from the handle 12 for replenishment once the cleaning tool 14 has been detached from the handle 12.

The fluid delivery system 34 comprises a pump assembly for drawing working fluid from the fluid reservoir 30 through the fluid inlet 36, and for delivering a burst of working fluid to the nozzle 32. The pump assembly is located within the body 16 of the handle 12, and comprises a positive displacement pump 38 and a drive for driving the pump 38. The drive preferably comprises a pump motor 40. A battery 42 for supplying power to the pump motor 40 is also located in the handle 12. The battery 42 is preferably a rechargeable battery.

A first conduit 44 connects the fluid inlet 36 of the fluid delivery system 34 to a fluid inlet 46 of the pump 38. A first one-way valve 48 is located between the fluid inlet 36 and the pump 38 to prevent water from returning to the fluid reservoir 30 from the pump 38. A second conduit 50 connects a fluid outlet 52 of the pump 38 to the nozzle 32. A second one-way valve 54 is located between the pump 38 and the nozzle 32 to prevent water from returning to the pump 38. A control circuit 56 controls the actuation of the pump motor 40, and so the pump motor 40 and the control circuit 56 provide a drive for driving the pump 38. The battery 42 supplies power to the control circuit 56. The control circuit 56 includes a motor controller which supplies power to the pump motor 40.

In this embodiment, the control circuit 56 receives signals generated when the user depresses the button on the handle 12 of the appliance 10. Alternatively, or additionally, the control circuit 56 may receive signals which are generated by a sensor located within the appliance 10, or which are received from a remote device, such as a display or a personal device. For brevity, in the following description the control circuit 56 receives signals which are generated when the user operates the button 18.

The appliance 10 comprises a drive mechanism for driving the movement of the stem 20, and thus the bristle carrier 26, relative to the handle 12. The drive mechanism comprises a transmission unit and a drive unit for driving the transmission unit to move the stem 20 relative to the handle 12. The drive unit comprises a drive motor 72 which is located within the body 16 of the handle 12. The control circuit 56 includes a motor controller which supplies power to the drive motor 72. The button 18 may also be used to activate and deactivate the drive motor 72, for example by depressing the button 18 a predefined number of times within a preset time period, to start, and subsequently stop, a cleaning session. Alternatively, a separate button (not shown) may be provided for activating and deactivating the drive motor 72. The transmission unit comprises a shaft which is driven by the drive unit to oscillate relative to the handle 12. The drive unit is preferably arranged to oscillate the shaft so that it oscillates about the longitudinal axis of the handle 12, preferably at a frequency in the range from 200 to 300Hz. The stem 20 of the cleaning tool 14 is mounted on the end of the shaft.

Figure 3 illustrates an exploded view of the pump assembly. The pump 38 comprises a pump housing, which in this embodiment comprises a plurality of sections. The pump housing comprises a lower housing section 80 in which the fluid inlet 46 and the fluid outlet 52 are formed, and an upper housing section 82. The lower housing section 80 of the pump housing defines a fluid chamber 84 for receiving fluid through the fluid inlet 46, and from which fluid is ejected through the fluid outlet 52.

The pump 38 further comprises a fluid displacement member which is moveable relative to the fluid chamber 84 to draw fluid into the fluid chamber 84, and subsequently to urge fluid from the fluid chamber 84 towards the nozzle 32. The fluid displacement member is preferably reciprocally moveable relative to the fluid chamber 84. In this embodiment, the pump 38 is in the form of a piston pump, in which the fluid displacement member is a piston 86 which is moveable within the fluid chamber 84. The piston 86 is moveable in a first direction to draw fluid into the fluid chamber 84 from the fluid reservoir 30, and in a second direction, opposite to the first direction, to subsequently urge fluid from the fluid chamber 84 towards the nozzle 32. In this example, the piston 86 is a relatively rigid member which is moveable within the fluid chamber 84 along a linear path between linearly spaced positions. A piston seal (not shown), which may be an O-ring, extends about the piston 86 to form a fluid-tight seal between the fluid chamber 84 and the piston 86. Alternatively, the pump may be in the form of a diaphragm pump, in which the fluid displacement member is a diaphragm bounding one side of the fluid chamber 84. In such a pump, the diaphragm is moveable, through flexing thereof, between different configurations to pump fluid.

The piston 86 forms part of a driven assembly that is driven by the drive of the pump assembly. The driven assembly also comprises a coupling member for coupling the piston 86 to the drive. In this embodiment, the coupling member comprises a flexible tether 88 which is connected at one end thereof to the piston 86. The pump housing supports a pulley 90 which guides the movement of the tether 88 as the piston 86 moves reciprocally relative to the fluid chamber 84.

The pump 38 also comprises an energy storage device which converts kinetic energy generated during the actuation of the pump 38 by the drive into potential energy which is stored by the energy storage device. In this embodiment, the energy storage device is in the form of a spring 92 provided within the pump housing. The spring 92 is a compression spring. As shown in Figure 4(c), the spring 92 has a first end which engages internal walls 96 of the lower housing section 80, and a second end which engages a radially enlarged section 94 of the piston 86 to urge the piston 86 in the second direction towards the fluid outlet 52.

As mentioned above, the drive comprises a pump motor 40. The pump motor 40 comprises a drive shaft 98 which is rotated by the pump motor 40. The drive shaft 98 is arranged so that it lies substantially parallel to the direction in which the piston 86 moves reciprocally within the pump housing. A worm gear 100 is connected to the end of the drive shaft 98 which is remote from the pump motor 40. The worm gear 100 protrudes through an aperture 102 formed in the lower housing section 84 to enter the pump housing.

The drive is connected to the driven assembly by a freewheel, or unidirectional, clutch 104 located within the pump housing and supported for rotation relative to the pump housing by bearings 106. The clutch 104 comprises a rotatable input section in the form of an outer ring 108 which has teeth which mesh with the worm gear 100 so that, with rotation of the worm gear 100 by the pump motor 40, the outer ring 108 rotates relative to the pump housing about an axis which is orthogonal to the drive shaft. In this embodiment, the outer ring 108 is rotated by the drive in an anti-clockwise direction, as viewed in Figure 4(c).

The clutch 104 further comprises a rotatable output section in the form of an inner member 110, and a cage 112 which houses a set of rollers and springs which engage the cage 112 and the inner member 110 so as to inhibit rotation of the inner member 110 in a clockwise direction, as viewed in Figure 4(c), relative to the outer ring 108, and to allow rotation of the inner member 110 in an anticlockwise direction in each of two different states of the clutch 104. In a first, coupled state of the clutch 104, the inner member 110 rotates with the outer ring 108 in an anticlockwise direction relative to the pump housing, and in a second, freewheeling state of the clutch 104, the inner member 110 rotates relative to the outer ring 108 in an anticlockwise direction.

A crankshaft 114 is connected to the inner member 110 so as to rotate with the inner member 110. The crankshaft 114 comprises a pin 116 which is arranged parallel to, but offset from, the rotational axis of the outer ring 108 and the inner member 110. A bearing 118 extends about the pin 116, and a looped free end 120 of the tether 88 is attached to the bearing 118.

Through the connection of the piston 86 to the inner member 110 of the clutch 104, the spring 92 applies a force to the inner member 110 which urges it to rotate relative to the pump housing. The state adopted by the clutch 104 is dependent on the direction in which the inner member 110 is urged to rotate relative to the pump housing by the force applied to it by the spring 92. As viewed in Figure 4(c), when the inner member 110 is urged to rotate in a clockwise direction by the spring 92, the clutch 104 adopts its coupled state and so the inner member 110 rotates with the outer ring 108 in an anticlockwise direction. When the inner member 110 is urged to rotate in anti -clockwise direction by the spring 92, the clutch 104 adopts its freewheeling state and so the inner member 110 rotates relative to the outer ring 108 in the anticlockwise direction.

In Figures 4(a) to 4(c), the pump assembly is illustrated at the start of a coupled state of the cutch 104 following the ejection of a burst of fluid from the fluid chamber 84. The piston 86 is located in a first position relative to the pump housing, in which the radially enlarged section 94 of the piston 86 is urged against an internal wall of the pump housing. The inner member 110 is in a first angular position relative to the pump housing, in which the inner member 110 is urged to rotate in a clockwise direction by the force of the spring 92.

To draw a volume of fluid into the fluid chamber 84, the control circuit 56 operates the pump motor 40 to rotate the worm gear 100 and drive rotation of the outer ring 108 of the clutch 104. As illustrated in Figures 5(a) to 5(c), with rotation of the worm gear 100 the inner member 110 rotates with the outer ring 108 to move the piston 86 away from its first position and towards a second position, shown in Figure 6(a) to 6(c). As the piston 86 moves towards its second position, the spring 92 becomes compressed, converting kinetic energy into potential energy which is stored by the compressed spring 92. The compressed spring 92 thus acts on the piston 86 so as to urge the piston 86 back towards the first position.

The clutch 104 remains in its coupled state until the inner member 110 is in a second angular position relative to the pump housing, as shown in Figures 6(a) to 6(c), and the piston 86 is in its second position. The second angular position of the inner member 110 is spaced from the first angular position by an angle of 180°. When the piston 86 has reached the second position, the pump assembly is in a primed configuration. The control circuit 56 stops the operation of the pump motor 40 to maintain the pump assembly in this primed configuration until the user operates the button 18 of the handle 12 to actuate the delivery of a burst of working fluid from the nozzle 32. During the coupled state of the clutch 104, the volume of fluid drawn into the fluid chamber 84 of the pump 38 is preferably in the range from 0.05 to 0.20 ml.

When the user operates the button 18, the control circuit 56 operates the pump motor 40 to rotate the outer ring 108 through a further 180° rotational movement. As soon as the outer ring 108 rotates from the position shown in Figure 6(c), the inner member 110 becomes urged to rotate in an anti -clockwise direction by the force of the spring 92, and so the clutch 104 transitions to a freewheeling state in which the inner member 110 can rotate relative to the outer ring 108. This enables the compressed spring 92 to use its stored potential energy to expand and actuate the pump 38 in reverse. The piston 86 moves rapidly back towards its first position under the action of the spring 92 to urge a burst of working fluid through the fluid outlet 52 towards the nozzle 32. Figures 7(a) to 7(c) illustrate the pump assembly as the piston 86 moves back towards its first position; in this configuration of the pump assembly there has been very little rotation of the outer ring 108 relative to the pump housing from the configuration shown in Figures 6(a) to 6(c).

Following the return of the piston 86 to its first position, as illustrated in Figures 4(a) to 4(c), the drive is operated to return the pump assembly to a primed configuration. The time taken for the pump assembly to return to a primed configuration to eject a second burst of fluid after the user has operated the button 18 to eject the first burst of fluid is preferably in the range from 0.4 to 0.6 seconds, and is preferably around 0.5 seconds. This allows the pump assembly to be operated to eject bursts of fluid at a frequency of around 2 Hz.