Fluid jetting device

Abstract

A fluid jetting device for a dental cleaning appliance comprising a helix assembly having a housing, a helix ramp with a cliff bottom and a cliff edge housed within the housing, a fluid chamber; a piston head coupled to the fluid chamber; a shaft extending through a through opening of the housing, the shaft is driven by a motor; a resilient means enveloping the housing adapted to urge apart from opposing ends of the shaft; and a cam follower coupled to the shaft adapted to move along the helix ramp such that rotation of the shaft causes the bearing to move from the cliff bottom towards the cliff edge where the fluid chamber is decompressed, and continuous rotation of the shaft causes the cam follower to move back to the cliff bottom where the fluid chamber is compressed.

Description

[0001] FLUID JETTING DEVICE

[0002] This relates to a dental treatment appliance with a fluid jetting device.

[0003] 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.

[0004] 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.

[0005] 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 recouple the pump to the drive.

[0006] SUMMARY

[0007] A first aspect of the disclosure describes a fluid jetting device comprising: a helix assembly having a housing, a helix ramp with a cliff edge and a cliff bottom housed within the housing, a fluid chamber; a piston head coupled to the fluid chamber; a shaft extending through a through opening of the housing, the shaft is driven by a motor; a resilient means enveloping the housing adapted to urge apart from opposing ends of the shaft; and a cam follower coupled to the shaft adapted to move along the helix ramp such that rotation of the shaft causes the cam follower to move from the cliff bottom towards the cliff edge where the fluid chamber is decompressed, and continuous rotation of the shaft causes the cam follower to move back to the cliff bottom where the fluid chamber is compressed.

[0008] In an embodiment of the first aspect of the disclosure, the fluid chamber comprises a diaphragm, an inlet and an outlet. The fluid chamber further comprises a diaphragm pin wherein a base on the diaphragm pin is overmould to the diaphragm. The diaphragm pin comprises an anti-movement mechanism. The anti-movement mechanism is at least two through openings defined on the base on the diaphragm pin and a portion of the diaphragm extends through the at least two through openings.

[0009] In an embodiment of the first aspect of the disclosure, the inlet comprises a first disc valve configured to prevent fluid from flowing out of the diaphragm, and the outlet comprises a second disc valve configured to prevent fluid from flowing into the diaphragm. The fluid chamber further comprises an upper pump head and a lower pump head, wherein the first and second disc valves are provided between the upper pump head and lower pump head. The lower pump head is arranged between the diaphragm and the upper pump head, and the lower pump head, upper pump head and diaphragm are secured by a pair of screws.

[0010] Alternatively, the inlet may comprise a first umbrella valve configured to prevent fluid from flowing out of the diaphragm, and the outlet comprises a second umbrella valve configured to prevent fluid from flowing into the diaphragm. The fluid chamber may further comprise an upper pump head and a lower pump head, wherein the first and second umbrella valves are provided between the upper pump head and lower pump head. The use of umbrella valves may provide improved sealing performance, particularly at high pressure.

[0011] In an embodiment of the first aspect of the disclosure, the fluid jetting device further comprising a lower chassis and an upper chassis arranged to house the fluid jetting device. The fluid jetting device further comprising a pump motor configured to drive the shaft. The opposing ends of the resilient means are in contact with the piston head and the pump motor. The resilient means is a helical spring.

[0012] In an embodiment of the first aspect of the disclosure, the motor comprises a disk having a cutout with the shaft inserted through the cutout and rotatable together with the shaft. The cutout is shaped of two vertically opposing V shaped cutout with vertically opposing angle X where the angle A is selected from a range of 5 to 60 degrees. In one embodiment, the angle X is approximately 40 degrees.

[0013] In an embodiment of the first aspect of the disclosure, the fluid jetting device further comprises a control circuit configured to control the rotation of the shaft such that the cam follower stops at a start point. In one embodiment of this embodiment, the start point is either the cliff top or the cliff bottom. A second aspect of the disclosure describes a dental treatment appliance comprising a handle, a fluid reservoir for storing a working fluid, a nozzle, a fluid jetting device according to the first aspect of the disclosure, and a control circuit configured to control the fluid jetting device to draw working fluid from the fluid reservoir and eject the working fluid out of the nozzle for delivering a burst of working fluid to the teeth of a user.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0016] Figure l is a perspective view, from the front, of a dental treatment appliance;

[0017] Figure 2 is a perspective view, from the rear, of the dental treatment appliance;

[0018] Figure 3 is an exploded view of the dental treatment appliance;

[0019] Figure 4 is an exploded front view of the fluid chamber;

[0020] Figure 5 is an exploded perspective view of the fluid chamber;

[0021] Figure 6 is an exploded perspective top view of the fluid chamber;

[0022] Figure 7 is an exploded perspective bottom view of the fluid chamber;

[0023] Figure 8 is a perspective view of the diaphragm;

[0024] Figure 9.1 is a top view of the diaphragm;

[0025] Figure 9.2 is a cross-sectional view along the line A-A of figure 9.1;

[0026] Figure 10.1 is a side view of the diaphragm;

[0027] Figure 10.2 is a cross-sectional view along the line B-B of figure 10.1;

[0028] Figure 11 is an exploded front view of the helix assembly and drive mechanism;

[0029] Figure 12 is an exploded perspective view of the helix assembly and drive mechanism;

[0030] Figure 13 is a perspective bottom view of the shaft and disk of the motor;

[0031] Figure 14.1 is a bottom view of a cutout of the disk and the shaft when the shaft is engaged with the disk;

[0032] Figure 14.2 is a bottom view of a cutout of the disk and the shaft when the shaft is disengaged with the disk; Figure 14.3 is a bottom view of a cutout of the disk illustrating the angle of the free play;

[0033] Figure 15 is a cross section view of the helix assembly;

[0034] Figure 16.1 is a part cut out of the housing of the helix assembly;

[0035] Figure 16.2 is a perspective view of the fluid jetting device;

[0036] Figure 17 is a cross section view of the fluid jetting device when the diaphragm is in an uncompressed state;

[0037] Figure 18 is a cross section view of the fluid jetting device when the diaphragm is in a compressed state;

[0038] Figure 19 is an exploded front view of an alternative fluid chamber; and

[0039] Figure 20 is an exploded perspective view of the alternative fluid chamber.

[0040] DETAILED DESCRIPTION OF THE INVENTION

[0041] Figures 1 and 2 illustrate external views of an embodiment of a dental treatment appliance 10. In this embodiment, the dental treatment 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 interproximal cleaning, gum treatment or tooth whitening.

[0042] The dental treatment 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 dental treatment 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 dental treatment 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 dental treatment 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 oral cavity.

[0043] The dental treatment 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 dental treatment 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 or above the nozzle 32.

[0044] The nozzle 32 forms part of a fluid jetting device 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, and in this embodiment is preferably in the range from 0.04 to 0.2 ml.

[0045] The fluid jetting device 34 is illustrated in Figures 3 - 18. In overview, the tip of the nozzle comprises a fluid outlet through which a burst of working fluid is delivered to the oral cavity of the user. The fluid jetting device 34 comprises a fluid inlet 46 for receiving working fluid from the fluid reservoir 30. In this embodiment, the working fluid is a liquid working fluid, which may be water, mouthwash or any fluid suitable for dental treatment. 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.

[0046] A lower chassis 45 and an upper chassis 47 form a housing for the fluid jetting device 34. The lower chassis 45 has a first portion defining a space to accommodate the fluid jetting device 34 and a second portion defining a space to accommodate the battery 42. The lower chassis 45 and upper chassis 47 are secured together by screws or other coupling means. When lower chassis 45 and upper chassis 47 are coupled together, the first portion of the lower chassis 45 and the upper chassis 47 houses the fluid jetting device 34. The first portion of the lower chassis 45 comprises a flat portion 451 to receive a flat portion 401 of the pump motor 40. This arrangement inhibits the pump motor 40 from moving rotationally with respect to the housing. This may be referred to as an anti-rotation mechanism. A battery 42 for supplying power to the pump motor 40 is also located in the second portion of the lower chassis 45. The battery 42 is preferably a rechargeable battery.

[0047] The fluid jetting device 34 comprises a fluid chamber 60, a helix assembly 70 and a drive mechanism 80.

[0048] Figures 4 to 10.2 illustrates the fluid chamber 60 comprising an upper pump head 61, a lower pump head 62, an inlet disc valve 48, an outlet disc valve 54, fluid inlet 46, fluid outlet 52, a diaphragm 67, a first conduit 44 and a second conduit 50.

[0049] The first conduit 44 connects the fluid inlet 46 of the fluid chamber 60 to a fluid inlet 36 of the fluid reservoir 30. The inlet disc valve 48 is coupled to the fluid inlet 46. The inlet disc valve 48 is one-way valve to prevent water from returning to the fluid reservoir 30 from the fluid chamber 60. A second conduit 50 connects the fluid outlet 52 of the fluid chamber 60 to the nozzle. The outlet disc valve 54 is coupled to the fluid outlet 52. The outlet disc valve 54 is a one-way valve to prevent water from returning to the fluid chamber 60. The valves are retained within a valve housing by a valve retainer, which is in the form of a circular plate. The inlet disc valve 48 and outlet disc valve 54 are provided between the upper pump head 61 and lower pump head 62.

[0050] The diaphragm 67 is located below the lower pump head 62, such that the lower pump head 62 is between the diaphragm 67 and the upper pump head 61. The lower pump head 62, upper pump head 61 and diaphragm 67 are secured by a pair of screws 68 which thread into a flange 452 of the lower chassis 45. This means that the fluid chamber 60 is fixedly secured to the lower chassis 45 and is non-movable. One skilled in the art will recognize that securing means other than screws may be implemented without departing from the disclosure.

[0051] The fluid chamber 60 further comprises a diaphragm pin 69 having a flat base 691 and a pin 692 extending from a center of the flat base 691. The flat base 691 is being overmould to the diaphragm. The diaphragm pin 69 comprises an anti-movement mechanism. Specifically, 6 through openings are defined around the circumference of the flat base 691 and a portion of the diaphragm extends through the 6 through openings 693. While figures 6, 7 and 10.2 illustrates 6 through openings, one skilled in the art will recognize that only 2 through openings spaced apart from each other would be sufficient to prevent relative movement between the diaphragm pin 69 and the diaphragm 67. The pin 692 may be a press fit pin. This means that the diaphragm 69 is retained to the piston head 77 via the press fit pin 692 which slides through a hole 774 in the piston 772. The press fit pin 692 has a hole 692 that aligns with a corresponding hole 775 provided on the piston 772 when the press fit pin 692 is inserted into the hole 774 in the piston 772. A securing means is inserted through both the holes 692 and 775 to secure the diaphragm 69 to the piston head 77. The securing means may be a pin, rod, screw or any means for securing the diaphragm 69 to the piston head 77. In another embodiment as shown in figures 8, 9.2 and 10.1, the diaphragm pin 69 has a threaded pin 692 and the piston 772 has complementary threaded line to receive the threaded pin 692. This means that the diaphragm pin 69 screwed into the piston 772. One skilled in the art will recognize that other forms of securing means can be implemented without departing from the disclosure.

[0052] The volume of the fluid chamber 60 is varied through elastic deformation of the diaphragm 67 by the diaphragm pin 69. The diaphragm pin 69 is reciprocally moveable in a linear direction relative to the housing of the fluid jetting device 34, and thus relative to the fluid chamber 90, to draw fluid into the fluid chamber 84, and subsequently to eject fluid from the fluid chamber 84 towards the nozzle 32.

[0053] Figures 11-16.2 illustrates the helix assembly 70 and the drive mechanism 80.

[0054] The drive mechanism 80 comprises a shaft 41 and a pump motor 40 for rotating the shaft 41. The pump motor 40 comprises a flat portion 401 to receive a flat portion 451 of the lower chassis 45. This arrangement inhibits the pump motor 40 from moving rotationally with respect to the housing. This may be referred to as an anti-rotation mechanism.

[0055] A through opening 411 is defined at a location along a length of the shaft 41. The through opening 411 is dimensioned accordingly to receive a cam follower 76. The through opening 411 is approximate the center of the exposed portion of the shaft 41. The pump motor 40 has a top end 412 and a bottom end 413. The top end 412 has a flat surface where one end of the resilient means 75 abuts onto. A disk 415 is provided at the top end 415. The disk 415 is rotatable together with the shaft 41. Figure 13 illustrates a perspective bottom view of the arrangement between the disk 415 and the shaft 41. The disk 415 defines a cutout 4151. The cutout 4151 is shaped of two vertically opposing V shaped cutout with vertically opposing angles X. Angle A is selected from a range of 5 to 60 degrees. In one embodiment, angle X is selected to be approximately 40 degrees. The cutout 4151 provides a certain degree of free play in the motor 40 to reduce gearbox backlash which can increase wear and also ensures that jet performance is maintained. Specifically, as the cam follower 76 the motor shaft 41 rolls over the “cliff edge” of the helix ramp 73, component forces generated by the potential energy in the resilient means 75 and transmitted to the piston head 77 accelerate the cam follower

[0056] 76. Hence, the cam follower 76 will cause the shaft 41 to rotate faster than the motor 40 immediately after cam follower 76 the motor shaft 41 rolls over the “cliff edge”. Figures 14.1 and 14.2 illustrate the engagement and disengagement between the shaft 41 and the disk 415. As shown in figure 14.1, the shaft 41 and the cutout 4151 are engaged and rotate uniformly in an anti-clockwise direction 4152. As the cam follower 76 the motor shaft 41 rolls over the “cliff edge” of the helix ramp 73, the shaft 41 and the cutout 4151 are disengaged and rotate in different speed in the anti-clockwise direction 4152, where the shaft 41 rotates at a speed that is faster than the motor. Consequently, the shaft 42 bounces away from the contact surface 4154 of the cutout 4151 and disengages from the contact surface 4154 of the cutout 4151 as shown in arrow 4153 in figure 14.2. Shortly after, the shaft 41 and the cutout 4151 will re-engage again and rotate uniformly in the anti-clockwise direction 4152 at least until the cam follower 76 the motor shaft 41 rolls over the “cliff edge” of the helix ramp 73. Without this free play, the time it takes the cam follower 76 to reach the end of its stroke length is increased due to dragging of the cam follower 76 on the cliff wall which in turns reduces the jet pressure generated.

[0057] The helix assembly 70 comprises a housing 71, a resilient means 75 and a piston head

[0058] 77. Housed within the housing 71 includes the cam follower 76, an upper bush 712 and a lower bush 713. The resilient means 75 is a helical spring enveloping the housing 71 adapted to urge apart from opposing ends of the housing 71. Opposing ends of the helical spring are in contact with the piston head 77 and the flat surface of the top end 412 of the pump motor 41. The flat surface of the top end 412 of the pump motor 41 has a diameter bigger than the diameter of the resilient means 75.

[0059] The upper bush 712 is loosely coupled to an open end 414 of the shaft 41. The upper bush 712 is inserted into a cavity of the protrusion 773. The lower bush 713 is loosely coupled to shaft 41 proximate the disk 415. The lower bush 713 is inserted into a cavity at the base 72 of the housing 71. The upper bush 712 and lower bush 713 ensure that the mating faces between the cam follower 76 and the helix ramp 73 are parallel. They also provide lubrication between the shaft 41 and housing and piston head to minimize wear in that area as the assembly slides up and down the shaft.

[0060] The piston head 77 has a base 771, piston 772 extending from a top surface of the base 771 and a circular protrusion 773 extending from a bottom surface of the base 771. The base 771 has similar diameter as the flat surface of the top end 412 of the pump motor 41

[0061] The piston 772 is shaped accordingly to receive the diaphragm pin 69. In one embodiment as shown in figures 6 and 7, the pin 692 is a press fit pin. Specifically, the diaphragm 69 is retained to the piston head 77 via the press fit pin 692 which slides through the hole 774 in the piston 772. The press fit pin 692 has a hole 692 that aligns with a corresponding hole 775 provided on the piston 772 when the press fit pin 692 is inserted into the hole 774 in the piston 772. A securing means is inserted through both the holes 692 and 775 to secure the diaphragm 69 to the piston head 77. The securing means may be a pin, rod, screw or any means for securing the diaphragm 69 to the piston head 77. In another embodiment as shown in figures 8, 9.2 and 10.1, the diaphragm pin 69 has a threaded pin 692 and the piston 772 has complementary threaded line to receive the threaded pin 692. This means that the diaphragm pin 69 screwed into the piston 772. One skilled in the art will recognize that other forms of securing means can be implemented without departing from the disclosure.

[0062] The protrusion 773 is shaped to fit into a receiving end of the housing 71. Particularly, the protrusion 773 has thread lines so that the piston head 77 is screwed into the receiving end of the housing 71. In short, the protrusion 773 of the piston head 77 threads into the threaded lines 711 of the housing 71. This means that the piston head 77 is secured to the housing with a thread between the two. The protrusion 773 defines a cavity 776. The cavity 776 extends from the bottom surface to the base 771. The cavity 776 has a first part and a second part where the first part extends from the bottom surface has a larger diameter than the second part. The first part is adapted to accommodate and receive the upper bush 712 while the second part is adapted to receive open end 414 of the shaft 41. The open end 414 of the shaft is adapted to freely move linearly along the length of the cavity 776. The cavity 776 provides a linear bearing surface constrain the piston head 77 to linear motion.

[0063] The motor shaft 41 only has a connection to the motor 40. It pulls down the piston head 77 using the cam follower 76 as the shaft rotates and in turn compresses the resilient means.

[0064] The cam follower 76 has a mounting portion 761 and a bearing portion 762. The mounting portion 761 has thread lines adapted to be fixedly screwed into the through opening 411. The bearing portion 762 is adapted to move around the helix ramp 73.

[0065] The housing 71 is circular in shape. The housing 71 has a base 72 at a bottom part of the housing 71. The base 72 has a helix ramp 73 with a cliff edge 74. The base 72 has a through opening 716 to receive the shaft 41. The through opening 716 extends through base 72 and is aligned with the longitudinal axis of the cavity 776. The through opening 716 has a first part and a second part where the first part extends from a bottom surface and has a larger diameter than the second part. The first part is adapted to accommodate and receive the upper bush 713 while the second part is adapted to receive the shaft 41. The shaft 41 extends through the through opening 716 and into the cavity 776. When the shaft 41 is inserted through the through opening 716, the helix ramp 73 spirals about the circumference of the shaft 41. Top part of the housing 71 defines an opening. The opening acts as the receiving end of the housing 71 to receive the protrusion 773 of the piston head 77. The opening has threaded lines 711 so that the piston head 77 can be fixedly secured to the housing 71. A side wall of the housing 71 defines a through hole 715 for assembly of the cam follower 76 into through opening 411. The dimension of the through hole 715 is larger than the dimension of the bearing portion 762 in order for the cam follower 76 to be inserted into the housing 71 and subsequently be coupled into the through opening 411.

[0066] A space is defined between the helix ramp 73 and the bottom of the protrusion 773 to accommodate movement of the cam follower 76. The helix ramp 73 has a start point and an end point. The movement of the cam follower 76 from the start point to the end point forms a stroke length which is also the distance the diaphragm is actuated to pull fluid in from the fluid inlet 46 and push fluid out of fluid outlet 52. As shown in figure 16.1, the helix ramp 73 includes a cliff edge 74, a cliff top 744, cliff bottom 741 and cliff wall 743. The cliff wall 743 is a vertical wall defined between the cliff edge and cliff bottom 741. The cliff top 744 is a flat region at the top end of the helix ramp 73. In one embodiment, the start and end points of the cam follower 76 is at the cliff top 744. In another embodiment, the start and end points of the cam follower 76 is at the cliff bottom 741. In yet another embodiment, the start and end points of the cam follower 76 is at a location of the helix ramp 73 between the cliff bottom 741 and cliff top 744. As shown in figure 16, the helix ramp 73 begins with a gentle upward slope from the cliff bottom 741 and transit to a steeper slope after a short distance away from the cliff bottom 741. The steeper section of the slope preferably extends at least 180° about the rotational axis of the cam follower 76, more preferably at least 270° about the rotational axis of the cam follower 76. When the drive mechanism 80 is arranged to stop the rotation of the cam follower 76, the cam follower 76 would be resting at the start point. If the start point is at the cliff bottom 741, the cam follower 76 would be resting on the relatively gentle section of the helix ramp 73. This can reduce the initial torque required to restart the rotation of the cam follower 76 when the drive mechanism 80 is actuated to initiate fluid ejection from the fluid chamber 60. If the start point is at the cliff top 744, the cam follower 76 would be resting on the flat region at the top end of the helix ramp 73 and this facilitates rapid reaction to trigger.

[0067] The cliff bottom 741 is preferably almost flat, that is, arranged substantially perpendicular to the rotational axis of the cam follower 76. The relatively steep section of the helix ramp 73 preferably extends at no more than 90° about the rotational axis of the cam follower 76, preferably between 45 and 90° about the rotational axis of the cam follower 76.

[0068] In one embodiment, the helix ramp 73 may have a substantially uniform gradient along its length from the bottom of the cliff 741 to the cliff edge 74. Alternatively, the gradient may vary along the length of any part of the helix ramp 73. The choice of the gradient is dependent on the design consideration of torque required to move the bearing 76 around the helix ramp 73.

[0069] The helix ramp 73 may comprise a single ramp extending no more than 360° about the rotational axis of the cam follower 76. However, the helix ramp 73 may comprise a plurality of ramps each extending partially about the rotational axis of the cam follower 76. Each ramp may have substantially the same shape, and so extend about the rotational axis of the cam follower 76 by the same amount. For example, the helix ramp 73 may comprise two ramps which each extend no more than 180° about the rotational axis of the cam follower 76, with the start of one ramp being located angularly adjacent, but axially spaced from, the end of the other ramp. In this case, providing two ramps can allow a burst of fluid to be ejected from the pump assembly following a 180° rotation of the cam follower 76, or two bursts of fluid to be ejected in rapid succession following a 360° rotation of the cam. Depending on the gradients of the ramp, the volume of the fluid ejected from the fluid chamber 60 as the cam follower 76 moves beyond the end of each ramp may be the same or less than that ejected when the helix ramp 73 comprises a single ramp extending substantially fully about the rotational axis of the ramp. For example, multiple, relatively small bursts of fluid may be ejected during a single 360° rotation of the cam. Alternatively, the fluid chamber 60 may be returned more rapidly to a primed configuration following ejection of a single burst of fluid.

[0070] Figure 17 illustrates the fluid chamber in decompressed state while figure 18 illustrates the fluid chamber in compressed state.

[0071] Position sensing and control circuitry are provided to operate the movement of the cam follower 76 from the start to the end points.

[0072] In the embodiment where the start and end points of the cam follower 76 is at the cliff top 744. At rest state, the fluid chamber 60 is in decompressed state as shown in figure 17. In this decompressed state, the fluid chamber 60 is loaded with fluid from previous use. Once the control circuitry activates the drive mechanism 80 to initiate fluid ejection from the fluid chamber 60, the cam follower 76 travels along the helix ramp 73 from the start point to the end point. As the cam follower 76 moves beyond the cliff edge 74, the cam follower 76 drops to the cliff bottom 741 and the potential energy from the resilient means 75 is released, causing the piston head 77 to move back to its original position as shown in arrow 1703 as shown in figure 18, ejecting fluid in the diaphragm 67 out of the fluid chamber 60 via the fluid outlet 52. In other words, the stored potential energy is used to actuate the piston head 77 to urge fluid out of the fluid chamber once the cam follower 76 moves beyond the cliff edge 74. The fluid chamber 60 is now in a compressed state where the cam follower 76 is at the cliff bottom 741 as shown in figure 18. The cam follower 76 now travels along the helix ramp 73 from the cliff bottom 741 and back to the end point at the cliff top 744 to complete one stroke length. During this transition, the piston head 77 moves towards the pump motor 40 as shown in arrow 1701. Consequently, the piston head 77 also pulls the diaphragm pin 69 towards the pump motor 40 causing the diaphragm 67 to transit from a compressed state to an uncompressed state as shown in figure 17. As the diaphragm 67 transits from the compressed state to the uncompressed state, fluid is drawn from the fluid reservoir 30 via the fluid inlet 46 and collected in the diaphragm 67 priming the fluid jetting device for the next jet of fluid. In the first stroke, fluid from previous use would be ejected and subsequently the diaphragm 67 would draw fluid from the fluid reservoir 30 via the fluid inlet 46. Essentially, the priming and purging of the fluid jetting device uses fluid from previous use to immediate purge and flush the fluid jetting device. Subsequent strokes would repeat the process of filling up the diaphragm 67 from the fluid reservoir 30 via the fluid inlet 46 and ejecting the fluid out of the fluid chamber.

[0073] In the embodiment where the start and end points of the cam follower 76 is at the cliff bottom 741, the first stroke will begin with draw fluid from the fluid reservoir 30 via the fluid inlet 46 and subsequently eject the fluid to prime and purge the fluid jetting device. Subsequent strokes would repeat the process of filling up the diaphragm 67 from the fluid reservoir 30 via the fluid inlet 46 and ejecting the fluid out of the fluid chamber.

[0074] When cam follower 76 travels along the helix ramp 73 from the cliff bottom 741 to the cliff top 744, the resilient means 75 is compressed, translating the kinetic energy to stored potential energy. Once the cam follower 76 moves beyond the cliff edge 74, the potential energy is released, i.e. the resilient means 75 is uncompressed, where the cam follower 76 drops back to the cliff bottom 741 causing the piston head 77 to move back to its original position as shown in arrow 1703 as shown in figure 18, ejecting fluid in the diaphragm 67 out of the fluid chamber 60 via the fluid outlet 52. In other words, the stored potential energy is used to actuate the piston head 77 to urge fluid out of the fluid chamber once the cam follower 76 moves beyond the cliff edge 74.

[0075] The fluid jetting device essentially requires the helix assembly 70 and drive mechanism 80 to provide linear movement of the piston head 77, and in turn, causing the fluid chamber 60 to draw fluid from the fluid reservoir 30 via the fluid inlet 46 and subsequently eject the fluid out of the fluid outlet 52. Furthermore, the stored potential energy from the resilient means provides a sudden thrust to the piston head allowing this continuous drawing and ejecting of fluid to deliver a burst of working fluid to the nozzle.

[0076] For clarity, piston head 77 is fixedly secured to the housing 71. This means that the housing 71 moves linearly together with the piston head 77.

[0077] A control circuit is provided to control the actuation of the pump motor 40. The pump motor 40 and the control circuit provide a drive for driving the driving mechanism 80. The battery 42 supplies power to the control circuit. The control circuit includes a motor controller which supplies power to the pump motor 40 and a position sensor to determine the position of the cam follower 76. In this embodiment, the control circuit receives signals generated when the user depresses the button 18 on the handle 12 of the dental treatment appliance 10. Alternatively, or additionally, the control circuit may receive signals which are generated by a sensor located within the dental treatment 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 receives signals which are generated when the user operates the button 18.

[0078] The control circuit may be arranged to stop the rotation of the cam follower 76 immediately after a burst of fluid has been ejected from the fluid chamber, and so with the cam follower 76 positioned at or adjacent the start of the ramp. In this case, when a burst of fluid is required, the cam follower 76 requires rotation to first move the cam follower 76 along the helix ramp 73 to draw fluid into the fluid chamber, and then move the cam follower 76 beyond the cliff edge 744 so that a burst of fluid is urged from the fluid chamber. This positioning of the cam follower 76 at the cliff bottom 741 results in the fluid jetting device being held in an “unprimed” or empty, configuration following the ejection of fluid from the fluid chamber. As this results in a relatively long time delay between the start of the rotation of the cam follower 76 and the delivery of a burst of fluid from the fluid chamber, the control circuit may be configured to control the drive mechanism to stop the shaft such that the cam follower 76 stops at the cliff top 744, and thus following the movement of the cam follower 76 along the helix ramp to fill the fluid chamber. This can allow the fluid jetting device to be held in a “primed” or full, configuration so that a burst of fluid can be output from the fluid chamber relatively rapidly, for example, within less than 0.5-30 seconds from user demand.

[0079] The control circuit comprises a position sensor for detecting the position of a moving component of the fluid jetting device. For example, the position sensor may be arranged to detect the location of the cam follower 76. Alternatively, the position sensor may be arranged to detect the linear position of the piston head 77. The position sensor may be an optical sensor for detecting the position of a moving component such as the cam follower 76, piston head 77, or shaft 41. Alternatively, the position sensor may be a magnetic sensor, such as a Hall Effect sensor, for detecting the position of a magnet mounted on the moving component. In one embodiment, a magnet is located on the cam follower 76, and the position sensor is located on the housing 71, which is positioned adjacent to, or mounted on, the housing 71 such that the position sensor is at proximate the start point.

[0080] The control circuit is any circuitry to receive signals from the position sensor and button 18 and control the drive mechanism to drive the shaft. The control circuit is powered by the battery and may also act as a power regulator of the drive mechanism to drive the shaft as and when required. The control circuit is well known and hence omitted for brevity.

[0081] Figures 19 and 20 illustrate an alternative example of a fluid chamber 160 which can be used in the fluid jetting device 34. The alternative fluid chamber 160 has substantially the same structure and function as the fluid chamber 60 described with reference to Figures 4 to 10.2, and common features will not be described again for brevity. Common features have the same reference number, but increased by 100. Only differences in structure and operation are described herein.

[0082] The fluid chamber 160 comprises an upper pump head 161, a lower pump head 162, an inlet valve 155, an outlet valve 156, a sealing element 163, fluid inlet 146, fluid outlet 152, a diaphragm 167, a first conduit 144, and a second conduit 150.

[0083] The first conduit 144 connects the fluid inlet 146 of the fluid chamber 160 to a fluid inlet 36 of the fluid reservoir 30. The inlet valve 155 is coupled to the fluid inlet 146. The inlet valve 155 is a one-way valve to prevent water from returning to the fluid reservoir 30 from the fluid chamber 160. A second conduit 150 connects the fluid outlet 152 of the fluid chamber 160 to the nozzle. The outlet valve 156 is coupled to the fluid outlet 152. The outlet valve 156 is a one-way valve to prevent water from returning to the fluid chamber 160. Both the inlet valve 155 and the outlet valve 156 are umbrella valves. Umbrella valves can provide improved sealing performance, particularly at higher fluid pressures, thereby reducing leakages. The valves are retained within a valve housing by a valve retainer. The inlet valve 155 and outlet valve 156 are provided between the upper pump head 161 and lower pump head 162.

[0084] The lower pump head 162 comprises an inlet chamber 157 and an outlet chamber 159. The inlet chamber 157 is configured to be coupled to the fluid inlet 146, when the inlet valve 155 is open. The outlet chamber 159 is configured to be coupled to the fluid outlet 152 when the outlet valve 156 is open. A sealing element or gasket 163 is provided on the lower pump head 163. The sealing element 163 is configured to seal the inlet chamber 157 and the outlet chamber 159, such that water does not leak between the inlet chamber 157 and the outlet chamber 159.

[0085] Both the upper pump head 161 and the lower pump head 162 comprise fixing points 158 which are coupled to fasteners (e.g., screws), which can be used to secure the upper pump head 161 and the lower pump head 162 to the lower chassis 45. This ensures that the fluid chamber 160 is fixedly connected to the lower chassis 45 and is non-movable. One skilled in the art will recognize that securing means other than screws may be implemented without departing from the disclosure.

[0086] It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the accompanying claims.

Claims

CLAIMS1. A fluid jetting device comprising: a helix assembly having a housing, a helix ramp defining a cliff edge and a cliff bottom housed within the housing, a fluid chamber; a piston head coupled to the fluid chamber; a shaft extending through a through opening of the housing, the shaft is driven by a motor; a resilient means enveloping the housing adapted to urge apart from opposing ends of the shaft; a cam follower coupled to the shaft adapted to move along the helix ramp such that rotation of the shaft causes the cam follower to move from the cliff bottom towards the cliff edge where the fluid chamber is decompressed, and continuous rotation of the shaft causes the cam follower to move back to the cliff bottom where the fluid chamber is compressed.

2. The fluid jetting device according to claim 1, wherein the fluid chamber comprises a diaphragm, an inlet and an outlet.

3. The fluid jetting device according to claim 2, wherein the fluid chamber further comprises a diaphragm pin wherein a base on the diaphragm pin is overmould to the diaphragm.

4. The fluid jetting device according to claim 3, wherein the diaphragm pin comprises an anti-movement mechanism.

5. The fluid jetting device according to claim 4, wherein the anti-movement mechanism is at least two through openings defined on the base on the diaphragm pin and a portion of the diaphragm extends through the at least two through openings.

6. The fluid jetting device according to claim 2, wherein the inlet comprises a first disc valve configured to prevent fluid from flowing out of the diaphragm, and the outlet comprises a second disc valve configured to prevent fluid from flowing into the diaphragm.

7. The fluid jetting device according to claim 6, wherein the fluid chamber further comprises an upper pump head and a lower pump head, wherein the first and second disc valves are provided between the upper pump head and lower pump head.

8. The fluid jetting device according to claim 7, wherein the lower pump head is arranged between the diaphragm and the upper pump head, and the lower pump head, upper pump head and diaphragm are secured by a pair of screws.

9. The fluid jetting device according to claim 2, wherein the inlet comprises a first umbrella valve configured to prevent fluid from flowing out of the diaphragm, and the outlet comprises a second umbrella valve configured to prevent fluid from flowing into the diaphragm.

10. The fluid jetting device according to claim 8, wherein the fluid chamber further comprises an upper pump head and a lower pump head, wherein the first and second umbrella valves are provided between the upper pump head and lower pump head.

11. The fluid jetting device according to claim 1, further comprising a lower chassis and an upper chassis arranged to house the fluid jetting device.

12. The fluid jetting device according to claim 9, further comprising a pump motor configured to drive the shaft.

13. The fluid jetting device according to claim 10, wherein opposing ends of the resilient means are in contact with the piston head and the pump motor.

14. The fluid jetting device according to claim 11, wherein the resilient means is a helical spring.

15. The fluid jetting device according to any one of claims 10-12, wherein the motor comprises a disk having a cutout with the shaft inserted through the cutout and rotatable together with the shaft.

16. The fluid jetting device according to claim 13 wherein the cutout is shaped of two vertically opposing V shaped cutout with vertically opposing angle X.

17. The fluid jetting device according to claim 14 wherein the angle A is selected from a range of 5 to 60 degrees.

18. The fluid jetting device according to claim 15 wherein the angle X is approximately 40 degrees.

19. The fluid jetting device according to any preceding claim further comprising: a control circuit configured to control the rotation of the shaft such that the cam follower stops at a start point.

20. The fluid jetting device according to claim 17 wherein the start point is a cliff top proximate the cliff edge.

21. The fluid jetting device according to claim 17 wherein the start point is the cliff bottom.

22. A dental treatment appliance comprising: a handle; a fluid reservoir for storing a working fluid; a nozzle; a fluid jetting device according to any preceding claim; anda control circuit configured to control the fluid jetting device to draw working fluid from the fluid reservoir and eject the working fluid out of the nozzle for delivering a burst of working fluid to the teeth of a user.

Images