Vacuum cleaner head for vacuum cleaner

Abstract

A cleaner head for a vacuum cleaner is provided. The vacuum cleaner head is connectable to a suction airflow to clean a surface. The vacuum cleaner head includes an electrode for generating an electrostatic field between the electrode and the surface to be cleaned to apply a force to move dust particles toward the electrode and into a flow path of the airflow to promote entrainment of the dust particles within the airflow. The invention also provides a vacuum cleaner comprising a cleaner head and a vacuum motor for driving a suction airflow, the cleaner head being connected to the suction airflow.

Description

Technical Field

[0001] The present invention relates to a vacuum cleaner head for a vacuum cleaner and a vacuum cleaner including the vacuum cleaner head. Specifically, although not exclusively, the present invention relates to a vacuum cleaner head that uses an electrostatic field to facilitate the entrainment of dust particles within an intake air stream, and to a vacuum cleaner including the vacuum cleaner head. Background Art

[0002] Dusting carpets is one of the key performance factors of vacuum cleaners. The ASTM F608 standard is used to measure the efficacy of vacuum cleaners and is calculated as the geometric mean of the pick-up fractions achieved on four types of carpets: shag carpets, multi-level carpets, plush carpets, and level loop carpets. Traditional floor care techniques have lower scores on shag carpets and multi-level carpets. This can have a disproportionately negative impact on the overall pick-up fraction. Therefore, it is desirable to improve the ability of the vacuum cleaner head and / or the vacuum cleaner to draw dust (i.e., dust particles) from deep within the carpet in order to increase the final geometric mean ASTM F608 score of the vacuum cleaner head / vacuum cleaner.

[0003] Furthermore, there is a continuing drive to reduce the energy required to pick up dust particles from the floor surface, i.e., from carpets and hard floors. It may be helpful to use a mechanism other than mechanical agitation and / or a strong intake air stream to agitate or move dust particles from the surface to be cleaned, which can be energy-intensive.

[0004] It is well known that as particles become smaller, the balance of different physical forces acting on them changes. For example, as the particle size decreases from 1 mm to 1 µm, dust particles become less susceptible to gravity, mechanical agitation, and air flow, and instead become more susceptible to electrostatic forces, capillary forces, and van der Waals forces. Therefore, the behavior of ultrafine dust (e.g., consisting of dust particles < 1 µm) is governed by electrostatic forces, capillary forces, and van der Waals forces, rather than by gravity, mechanical agitation, and air flow.

[0005] Due to these properties of small particles, dust particles up to 1 mm can be processed within a distance of up to 1 cm by using an electrostatic field. In addition, it is known that approximately 99% of the mass of the dust particle mixture used in the ASTM pick-up test is provided by particles smaller than 425 µm (ASTM F608 A1). Therefore, by using electrostatic agitation instead of / in addition to mechanical agitation and / or an intake air stream, the pick-up performance of the vacuum cleaner, particularly on carpets, and / or its energy efficiency can be improved.

[0006] In view of the above considerations, the present invention has been designed. Summary of the Invention

[0007] In a first aspect, the present invention provides a vacuum cleaner head for a vacuum cleaner, the vacuum cleaner head being connectable to an intake airflow to clean a surface;

[0008] wherein the vacuum cleaner head includes an electrode for generating an electrostatic field between the electrode and the surface to be cleaned, to apply a force to move dust particles towards the electrode and into the flow path of the airflow, thereby facilitating the entrainment of the dust particles within the airflow.

[0009] Advantageously, providing an electrode for generating an electrostatic field for the vacuum cleaner head can enhance the pick-up ability of the vacuum cleaner head. That is, the electrostatic field generated by the electrode causes dust particles from the surface to be cleaned (such as a carpet / hard floor) to be subjected to a force directed towards the electrode.

[0010] Preferably, in addition to mechanical agitation, the dust particles are also electrostatically agitated, for example, by brush bars mounted on the surface engaging portion of the vacuum cleaner head. The electrode can extend along / around the entire length of the brush bar. When the brush bar is circular, the electrode can, for example, extend around it to form a helical electrode surface. The electrode can be exposed to air (i.e., uncovered) or can be covered, for example, embedded in a part of the vacuum cleaner, such as a brush bar, in order to benefit from electrical insulation. Alternatively, the vacuum cleaner head can be used as a solid powder atomization device, which does not use mechanical agitation but only electrostatic agitation to generate a continuous stream of atomized solid particles, which are fed into the intake airflow.

[0011] Depending on the size of the dust particles and the type of the surface to be cleaned, the dust particles are affected differently in the generated electrostatic field. For example, small dust particles (such as <10 μm) are accelerated towards the electrode, causing them to rise from the surface to be cleaned and possibly be completely atomized. Larger dust particles (such as 10 μm - 500 μm) cannot be completely atomized but can be temporarily lifted from the surface to be cleaned, which is sufficient to facilitate their entrainment within the intake airflow. Regardless of size, most of the dust particles in the generated electrostatic field are subjected to a force that moves them towards the electrode and into the flow path of the intake airflow. Thus, dust particles can be more easily picked up from a hard floor or a carpet, for example, by sucking them from within the carpet to the carpet surface. Then, the dust particles can be guided into the flow path of the intake airflow and be entrained therein, thereby enhancing the efficacy of the vacuum cleaner head. Here, entrainment means that the dust particles are captured within the intake airflow, for example, such that they can be guided to a filter element within a vacuum cleaner including the vacuum cleaner head.

[0012] Optional features of the present invention are outlined below. The present invention includes combinations of the said aspects and optional features, unless such combinations are clearly impermissible or explicitly avoided.

[0013] Optionally, the electrode can be a mesh electrode, which includes a conductive frame defining a plurality of openings configured to allow dust particles to pass therethrough into the air stream. Here, conductive means electrically conductive. The plurality of openings can together form the opening area of the mesh electrode, while the conductive frame can form the enclosed area of the mesh electrode. It may be desirable to maximize the opening area of the mesh electrode so as to maximize the proportion of dust particles passing through the mesh electrode into the suction air stream. For example, the opening area of the mesh electrode can be at least 35% to 99% of the total area of the mesh electrode, such as 35% to 95%. Generally, the opening area of the mesh electrode can be maximized by implementing the mesh electrode as a single-wire electrode.

[0014] Optionally, each of the plurality of openings of the mesh electrode can have an area of at least 0.28 mm 2 or at least 0.79 mm 2 . It has been found that such an area allows a sufficient proportion of the accelerated dust particles to pass through the mesh electrode (and not contact the conductive frame, which may cause the dust particles to stick to the conductive frame and / or fall back onto the surface to be cleaned). Specifically, the lower limit of 0.28 mm 2 corresponds to a circular opening with a diameter of 600 μm, which is equal to the maximum diameter of the silica particles used in the ASTM F608 test. Thus, by ensuring that each of the plurality of openings of the mesh electrode has an area of at least 0.28 mm 2 , it can be ensured that the mesh electrode does not act as a sieve preventing the pickup of particles smaller than 600 μm. The lower limit of 0.79 mm 2 can improve the safety of operation.

[0015] Optionally, the conductive frame of the mesh electrode is composed of multiple strands defining the openings, and the maximum thickness of each strand is 1 mm or less. This maximum thickness can correspond to the thickness of the strand along the plane of the mesh; or the thickness of the strand of the mesh in a direction transverse to the plane of the mesh, or both. The plane of the mesh is here considered to be the plane in which all the strands lie. This is usually a flat plane, but can also be curved. For example, the maximum thickness of each strand can be about 0.7 mm. Varying the thickness of the strands can allow the resulting electrostatic field and / or the enclosed area of the mesh electrode to vary as needed.

[0016] Optionally, each of the plurality of openings of the mesh electrode can be polygonal. Preferably, each of the plurality of openings of the mesh electrode can be hexagonal. Alternatively, if not polygonal, each of the plurality of openings can be circular.

[0017] Typically, the electrode can be connected to a power source to create a potential difference and / or a voltage gradient between the electrode and the surface to be cleaned, thereby generating an electrostatic field. The potential difference can be constant or oscillating. In practice, the surface to be cleaned can be considered to be at zero potential, and the electrode can be connected to the power source such that it is at a positive or negative non-zero potential, thereby providing a potential difference and / or a voltage gradient with positive or negative polarity, respectively, therebetween.

[0018] Optionally, the polarity of the generated potential difference can vary over time. For example, the polarity can switch periodically, such as cyclically, from positive to negative and vice versa. Additionally or alternatively, the magnitude of the potential difference can vary over time, such as by switching periodically. This can be done, for example, at regular time intervals. Conveniently, changing the polarity and / or magnitude of the potential difference can mitigate the risk of dust particles being polarized by the electrostatic field, which polarization can impede the pick-up performance of the vacuum head.

[0019] Optionally, the ratio of the generated potential difference to the distance between the electrode and the surface to be cleaned can be 3 MV / m or less. This value corresponds to the breakdown voltage of air. Thus, by not exceeding this value, it can be ensured that the air between the electrode and the surface to be cleaned does not break down into ozone and plasma, which can impede the pick-up performance of the vacuum head and / or pose a safety hazard. Additionally, experiments have shown that dust particles with a size < 425 µm are most susceptible to a field strength approaching 3 MV / m.

[0020] Optionally, the generated potential difference can be in the range of 1 kV to 10 kV. Preferably, the generated potential difference can be 6 kV or less, 4 kV or less, 2.6 kV or less, and / or 2.5 kV or less.

[0021] Optionally, the electrode can be mounted near the surface engagement portion of the vacuum head such that, in use, the distance between the electrode plane and the surface to be cleaned is 5 cm or less.

[0022] For example, the potential difference generated between the electrode and the surface to be cleaned can be 6 kV at a distance of 5 mm, 4 kV at a distance of 3 mm, 2.5 kV at a distance of 2 mm, and / or 1 kV at a distance of 1 mm. A suitable configuration can be selected based on the type of surface to be cleaned (e.g., hard floor or carpet) and / or the size of the dust particles. Generally, it has been observed that, due to the relatively low settling velocity of smaller dust particles, compared to larger dust particles, smaller dust particles (e.g., < 10 µm) can be more easily lifted from the surface to be cleaned under the influence of the electrostatic field and are more easily entrained into the suction airflow.

[0023] Optionally, the electrode plane may be angled with respect to the surface to be cleaned to create a gradient in the electrostatic field. Preferably, the plane is angled such that the region of maximum field strength is positioned closest to the flow path of the suction airflow. Thus, the accelerated dust particles can be directed to the location where the suction airflow is strongest to facilitate their entrainment therein. For example, the acute angle between the electrode plane and the surface to be cleaned may be in the range of 0 to 45 degrees.

[0024] Optionally, the vacuum cleaner head may have a geometric mean ASTM F608 score of 25% or higher, preferably 30% or higher.

[0025] In a second aspect, the present invention provides a vacuum cleaner comprising:

[0026] a vacuum motor for driving a suction airflow; and

[0027] a vacuum cleaner head according to the first aspect, which is connected to the suction airflow.

[0028] Advantageously, compared to conventional vacuum cleaners, a vacuum cleaner comprising the vacuum cleaner head of the first aspect can simultaneously have reduced energy consumption and improved pickup efficiency. This is because enhancing the vacuum cleaner head with electrodes that generate an electrostatic field can be a more energy-efficient way to improve pickup efficiency compared to alternative solutions such as increasing the mechanical agitation provided by the vacuum cleaner head and / or the suction airflow intensity provided by the vacuum motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments and experiments illustrating the principles of the present invention will now be discussed with reference to the accompanying drawings, in which:

[0030] Figure 1 a vacuum cleaner head according to an embodiment of the present invention is schematically shown;

[0031] Figure 2 an experimental setup simulating the pickup performance of a vacuum cleaner head according to an embodiment of the present invention is schematically shown;

[0032] Figure 3A and 3B respectively show Figure 2 a schematic view and a magnified photograph of a part of the experimental setup;

[0033] Figure 4 schematically shows Figure 2 the mesh structure of the electrodes of the experimental setup;

[0034] Figures 5A to 5C shows Figure 4 three different configurations of the electrodes of FIGS. 4A and 4B relative to the surface to be cleaned containing dust particles;

[0035] Figure 6Shows the percentage breakdown of the different types of dust particles present in the dust particle mixture used in the ASTM F608 pick-up test; and

[0036] Figure 7 Is a graph showing the proportion of dust particles picked up from different types of surfaces to be cleaned by the Figure 2 experimental apparatus. DETAILED DESCRIPTION

[0037] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art. All documents mentioned herein are incorporated herein by reference.

[0038] Referring to Figure 1 the vacuum cleaner head 100 for a vacuum cleaner according to an embodiment of the present invention will be discussed. The vacuum cleaner head 100 can be connected to an intake air flow provided, for example, by a vacuum cleaner. The vacuum cleaner head 100 can include means for mechanically agitating dust particles on the surface to be cleaned. In Figure 1 an example, the vacuum cleaner head includes a rotatable brush bar 11 which forms the surface engaging portion of the vacuum cleaner head and provides mechanical agitation. The vacuum cleaner head 100 includes an electrode 4 for generating an electrostatic field between the electrode and the surface to be cleaned 2 to apply a force to move the dust particles 3 towards the electrode 4 and into the flow path of the intake air flow, thereby facilitating the entrainment of the dust particles within the air flow. The intake air flow can transport the entrained dust particles to, for example, a filter element and / or a bin of the vacuum cleaner including the vacuum cleaner head 100.

[0039] The electrode 4 is preferably a mesh electrode which includes a conductive frame defining a plurality of openings (see Figure 4 ), the plurality of openings being configured to allow the dust particles 3 to pass therethrough to enter the intake air flow. The electrode 4 is preferably mounted near the surface engaging portion of the vacuum cleaner head such that, in use, the distance between the electrode plane and the surface to be cleaned is 5 cm or less. In Figure 1 an example, the surface engaging portion is provided by the rotatable brush bar 11 and the electrode 4 is wound around an inner portion of the rotatable brush bar. The electrode extends along the entire length of the brush bar to form a helical electrode surface. Thus, the plane of the electrode 4 is curved, which allows the electrode to rotate together with the rotatable brush bar 11. Thus, at all times during use, a portion of the surface to be cleaned 2 is opposite a portion of the electrode in the depth direction such that the region between the electrode and the surface to be cleaned in the depth direction is always within the generated electrostatic field. Thus, the surface to be cleaned 2 can be simultaneously subjected to electrostatic agitation provided by the electrode and mechanical agitation provided by the rotatable brush bar. The electrode can be exposed to air (i.e., uncovered) or can be covered, for example, embedded in the brush bar, in order to benefit from electrical insulation.

[0040] To generate an electrostatic field, electrode 4 is connected to a power supply (not shown) to create a potential difference (i.e., voltage) and / or voltage gradient between electrode 4 and the surface 2 to be cleaned. The potential difference can be constant or oscillating. In practice, the surface to be cleaned is at 0 potential, and when electrode 4 is connected to the power supply, it is at a positive or negative non-zero potential, thereby providing a potential difference and / or voltage gradient with positive or negative polarity, respectively, therebetween. Preferably, the generated potential difference is in the range of 1 kV to 10 kV. For example, it can be 6 kV or less, 4 kV or less, 2.6 kV or less, and / or 2.5 kV or less. For example, the potential difference generated between electrode 4 and the surface 2 to be cleaned can be 6 kV at a distance of 5 mm, 4 kV at a distance of 3 mm, 2.5 kV at a distance of 2 mm, and / or 1 kV at a distance of 1 mm. A suitable configuration can be selected based on the type of surface to be cleaned (e.g., hard floor or carpet) and / or the size of the dust particles. Generally, it has been observed that due to the relatively low settling velocity of smaller dust particles, smaller dust particles (e.g., <10 μm) can be more easily lifted from the surface 2 to be cleaned under the influence of the electrostatic field and are more easily entrained into the suction airflow compared to larger dust particles.

[0041] In Figure 1 the example of Figure 1 the left-hand side arc in Figure 1 ), the first half 12a of electrode 4 is held at a positive potential to create a positive polarity between the electrode and the surface 2 to be cleaned, and the second half 12b of the electrode ( Figure 1 the right-hand side arc in Figure 1 ) is held at a negative potential to create a negative polarity between the electrode and the surface to be cleaned. The two parts 12a, 12b of electrode 4 are electrically insulated from each other so that they can maintain opposite polarities. In Figure 1 the example of Figure 1 , this is achieved by a pair of electrical insulators 13a, 13b interposed between the two parts 12a, 12b of electrode 4. As the brush bar 11 rotates (as shown by the clockwise arrow in Figure 1 ), the two parts 12a, 12b of electrode 4 also rotate relative to the surface to be cleaned, such that the polarity of the generated potential difference switches periodically, e.g., at regular time intervals. Conveniently, this can reduce the risk of the dust particles 3 being polarized by the electrostatic field, which would otherwise impede the pickup performance of the vacuum head. It is conceivable that, in addition to or instead of changing the polarity, the magnitude of the potential difference can vary over time to achieve the same effect. For example, this can be achieved using Figure 1 the configuration of

[0042] Next, referring to Figure 2 an experimental apparatus 1 for simulating the pick-up performance of a vacuum cleaner head according to an embodiment of the present invention will be discussed. In fact, the experimental apparatus 1 acts as a solid powder atomization device that generates a continuous stream of atomized solid particles using only electrostatic agitation, without using mechanical agitation, which is fed into an inhalation airflow.

[0043] The experimental apparatus 1 includes a surface to be cleaned 2 provided by a substrate. The substrate 2 is provided with dust particles 3 deposited thereon. A mesh electrode 4 is disposed above the substrate 2 such that it covers the substrate 2 in the vertical direction. A suction hose 5 containing an inhalation airflow is disposed above the mesh electrode such that the mesh electrode is interposed between the substrate 2 and the inhalation opening 5a of the suction hose 5. The inhalation opening 5a of the suction hose 5 is spaced apart from the surface to be cleaned 2 such that the dust particles cannot be lifted and picked up solely by the inhalation airflow, i.e., without the assistance of the electrostatic field generated by the electrode 4.

[0044] The non-inhalation opening (not shown) of the suction hose 5 is connected to an externally controlled pump (not shown) that provides the inhalation airflow. The flow path of the inhalation airflow is from the mesh electrode towards vac, and is indicated by the arrow inside the suction hose 5 in Figure 2 A part of the substrate 2, the mesh electrode 4, and the extraction hose 5 including the inhalation opening 5a are all enclosed within an isolation box 6 containing a safety interlock device 10. The safety interlock device is used to prevent the electrode 4 from being turned on when the door (not shown) of the isolation box 6 is opened, thus ensuring operational safety. The electrode is electrically connected to a power supply 8 such that, in use, it is at a non-zero electric potential relative to the zero-potential substrate to generate a potential difference therebetween, which generates an electrostatic field. The potential difference can be monitored on an oscilloscope 7 connected to the power supply and a voltmeter connected to the electrode by using a high-voltage probe. The potential difference and / or its polarity (positive / negative) can be switched using a user-operable switch 9 on the power supply 8. For example, the potential difference can be constant or can oscillate. Conveniently, the polarity of the generated potential difference can vary with time, for example as discussed with respect to Figure 1 discussion.

[0045] Preferably, the ratio of the generated potential difference to the distance between the electrode 4 and the substrate 2 is 3 MV / m or less. By not exceeding this value, it can be ensured that the air between the electrode and the surface to be cleaned does not decompose into ozone and plasma, which would impede the pick-up performance of the vacuum cleaner head and / or pose a safety hazard. In addition, experiments have shown that dust particles with a size <425 µm are most susceptible to a field strength approaching 3 MV / m.

[0046] Figure 3A and 3B respectively show Figure 2 a schematic diagram and a magnified photograph of a part of the experimental apparatus. Figure 3A The schematic diagram of Figure 3BThe photographic illustrations are partial perspective views from the top and side. In both views, the substrate 2, the dust particles 3, the mesh electrode 4, and the suction opening 5a of the suction hose 5 are shown. The direction of the suction airflow is indicated by Figure 3A the arrows in Figure 1 . The electrode 4 is mounted at a distance d of 5 cm or less from the substrate 2 for optimized electrostatic field generation. In this example, the potential difference generated at a distance d = 10 mm is 16 kV. However, in a vacuum cleaner head configuration 100 such as

[0047] shown, for safety reasons, it is preferred that the potential difference does not exceed 10 kV. Figure 4 The structure of the mesh electrode 4 is discussed in more detail with respect to

[0048] . As described above, the mesh electrode 4 includes a plurality of openings 4b provided by a conductive frame 4a. The plurality of openings 4b together form the opening area of the mesh electrode 4, while the conductive frame 4a forms the enclosed area of the mesh electrode. It is generally desirable to maximize the opening area of the mesh electrode so as to maximize the proportion of dust particles 3 passing through the mesh electrode and into the suction airflow. For example, the opening area of the mesh electrode can be at least 35% to 99% of the total area of the mesh electrode. Figure 1 The conductive frame 4a of the mesh electrode 4 is composed of multiple strands that define the openings 4b, and the maximum thickness of each strand is 1 mm or less. In this example, the maximum thickness of each strand is approximately 0.7 mm. Varying the thickness of the strands can allow the generated electrostatic field and / or the enclosed area of the mesh electrode to vary as needed. Additionally, in this example, the maximum thickness corresponds to the thickness of the strands along the plane of the mesh and the thickness of the strands of the mesh in a direction transverse to the plane of the mesh. Here, the plane of the mesh is considered to be the plane in which all the strands lie. In this example, it is a flat plane, but it can also be curved (as discussed with reference to 2 to 2 ). In this example, each of the plurality of openings 4b of the mesh electrode 4 is polygonal, specifically hexagonal. It is contemplated that the openings can be non-polygonal, such as circular for example. For instance, the hexagons can each have a side length of 5 mm or 6 mm. Thus, in a preferred embodiment, the area of each of the plurality of openings 4b of the mesh electrode 4 is in the range of 65 mm

[0049] The conductive frame 4a can be formed by braiding multiple strands, overlapping them, or forming them integrally to provide the frame. Generally, the conductive frame can be formed in any way as long as it can act as an electrode and provide openings to achieve the mesh structure.

[0050] Next, with reference to Figures 5A to 5C three different configurations of the electrode 4 with respect to the surface 2 to be cleaned containing the dust particles 3 are discussed. Figure 4 .

[0051] In a first configuration (see Figure 5A ), the plane of the electrode 4 is flat and angled with respect to the surface 2 to be cleaned (the substrate on which dust particles 3 are deposited), so as to create a voltage gradient therebetween when the electrode is connected to the power supply 8. The voltage gradient in turn creates a gradient in the electrostatic field generated. Thus, at the place where the distance between the electrode 4 and the surface 2 to be cleaned is the smallest (i.e., at the Figure 5A rightmost corner of the substrate 2 in ), the electrostatic field generated is the strongest. Therefore, the dust particles in the generated electrostatic field are subject to a force having components towards the electrode 4 and towards the right end of the substrate 2 (i.e., the place where the electrostatic field is the strongest). The dust particles used in this example are coarse dust particles (i.e., their size is in the range of 10 μm - 500 μm). Thus, under the action of the generated electrostatic field, the dust particles are "swept" in piles to the right corner of the substrate and partially protrude from the openings 4b of the mesh electrode 4. Conveniently, by changing the orientation and relative angle of the electrode plane with respect to the surface 2 to be cleaned, the dust particles can be swept into, for example, the area closest to the flow path of the suction air stream and / or the area where the suction air stream is the strongest. Thus, the entrainment of the dust particles 3 in the suction air stream can be improved. Specifically, it has been found that it is beneficial to configure the electrode 4 with respect to the surface 2 to be cleaned such that the acute angle α therebetween is in the range of 0 to 45 degrees.

[0052] Next, refer to Figure 5B to discuss the second configuration. In this example, the mesh electrode 4 is parallel to the surface 2 to be cleaned, as shown in Figure 2 and 3. The size of the dust particles is selected to be smaller, i.e., < 20 μm. Thus, under the action of the electrostatic field generated by the electrode, the fine dust particles are accelerated towards the electrode and completely atomized, as shown by the atomization cloud 3' on the Figure 5B right side. Therefore, due to their relatively small size with respect to the opening area of the electrode 4, most of the dust particles pass through the mesh. In addition, it has been observed that the atomization cloud 3' does not settle but remains suspended above the mesh electrode 4 for a relatively long time, ready to be picked up by the suction air stream. This relatively long settling time is due to the low settling velocity of the small particles.

[0053] Finally, refer to Figure 5C to discuss the third configuration. In this example, the electrode 4 is arranged with respect to the surface 2 to be cleaned in the same way as in Figure 5B , i.e., parallel to it. However, dust particles of different sizes are used. Specifically, the dust particles in this example are dust microparticles, i.e., coarse dust particles larger than Figure 5A and > 425 μm. Thus, under the action of the electrostatic field generated by the electrode 4, the dust microparticles 3 are accelerated towards the electrode 4 in a short time, then lose momentum and fall back to the surface 2 to be cleaned. Different from the Figure 5B fine dust particles, Figure 5CThe dust particles therein are temporarily lifted away from the surface 2 to be cleaned, rather than being suspended thereon indefinitely. However, it has been observed that this also has a beneficial effect on the pickup efficiency, since the particles are lifted near the suction airflow, allowing them to be entrained therein and carried away by it.

[0054] The ASTM F608 performance of the experimental apparatus 1 has been tested on different types of surfaces to be cleaned, each surface to be cleaned being provided with a mixture of dust particles, and the results are summarized in Figure 2 the figure of Figure 7 . Referring to Figure 6 the mass fraction breakdown of the ASTM F608 silica particle mixture shown, the appropriate type of dust particle mixture has been determined.

[0055] Figure 6 The figure of

[0056] Figure 2 shows the percentage breakdown of the different types of dust particles present in the dust particle mixture used in the ASTM F608 pickup test. The mixture is obtained by mixing silica sands of different size grades defined in the table. It has been found that 96% of the mixture mass is provided by dust particles with a size x in the range of 150 μm to 425 μm, more specifically, this corresponds to the middle 3 bins (150 - 212, 212 - 300, and 300 - 425 μm) of the ASTM F608 standard. Figure 7 is a figure showing the proportion of dust particles picked up from each type of surface. The types of surfaces to be cleaned include acrylic, PTFE, polycarbonate, stainless steel, polyethylene, shag carpet, Wilton carpet, and wood. The dust particle mixture includes the following types of dust particles classified by size: 150 μm, 212 μm, 300 μm, dolomite up to 500 μm in size, and silica powder with a size of 10 μm or less (e.g., commercially available R10 TM ). The sliding scale on the right side of the figure shows the color gradient corresponding to different proportions of dust particles picked up from the surface to be cleaned - ranging from 0 to 1 (i.e., 100%). The areas behind in the figure represent values for which the performance of the experimental apparatus 1 has not been tested.

[0057] Overall, the performance of the experimental apparatus 1 shows that setting a mesh electrode between the surface to be cleaned and the suction airflow can pick up most of the dust particles of different sizes for various surfaces without mechanical agitation or the help of the suction airflow (as described above, in the experimental apparatus, in order to verify the concept, the separate suction airflow cannot pick up any dust particles from the surface).

[0058] For example, it has been found that electrostatic agitation alone can pick up more than 83% (and up to 94%) of 212 μm and 300 μm dust particles from stainless steel and wood, allowing them to be subsequently transported away from the surface to be cleaned by an inhalation airflow. In terms of performance on carpet surfaces, such as shag and Wilton, significant pickup has also been observed. Approximately 12% of the 300 μm dust particles (which constitute nearly 32% of the mixture of dust particles) are picked up from the shag carpet by electrostatic agitation alone. In the case of Wilton carpets, under the action of the electrostatic field generated by the electrodes, Figure 6 more than 53% of the dust particles of each of the three sizes shown in Figure 7 are picked up.

[0059] Therefore, combining Figure 2 the electrostatic pickup technique of the experimental device with a device for mechanically agitating dust particles (such as Figure 1 the brush bar 11) can provide an energy-saving vacuum cleaner head with significantly improved pickup performance compared to existing floor care techniques. For example, it is estimated that such a vacuum cleaner head can have an improved geometric mean ASTM F608 score of at least 25% or at least 32%. In such a vacuum cleaner head, the separate inhalation airflow can pick up dust from the surface, but the presence of the electrodes allows for the removal or reduction of suction from the surface, thereby reducing energy consumption and increasing pickup.

[0060] The features disclosed in the foregoing description, or in the following claims, or in the drawings, expressed in their specific forms or in terms of means for performing the disclosed functions, or methods or processes for obtaining the disclosed results, may, where appropriate, be used alone or in any combination of these features to implement the invention in its different forms.

[0061] Although the invention has been described in connection with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art when the present disclosure is given. Therefore, the above exemplary embodiments of the invention are considered illustrative and not restrictive. Various changes can be made to the described embodiments without departing from the spirit and scope of the invention.

[0062] To avoid any doubt, any theoretical explanations provided herein are for enhancing the reader's understanding. The inventors do not wish to be bound by any of these theoretical explanations.

[0063] Any section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0064] Throughout the specification, including the claims which follow, unless the context requires otherwise, the words "comprise" and "include" and variations thereof will be understood to imply the inclusion of stated integers or steps or groups of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0065] 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 one particular value and / or to another particular value. Similarly, when values are expressed as approximations by use of the antecedent "about", it will be understood that the particular value forms another embodiment. The term "about" associated with a numerical value is optional and means, for example, + / - 10%.

Claims

1. A vacuum cleaner head for a vacuum cleaner, the vacuum cleaner head being connectable to an intake air flow to clean a surface; wherein, the vacuum cleaner head includes an electrode for generating an electrostatic field between the electrode and the surface to be cleaned to apply a force to move dust particles towards the electrode and into a flow path of the air flow, thereby facilitating entrainment of the dust particles within the air flow.

2. The vacuum cleaner head according to claim 1, wherein, the electrode is a mesh electrode including a conductive frame defining a plurality of openings configured to allow dust particles to pass therethrough to enter the air flow.

3. The vacuum cleaner head according to claim 2, wherein, Each of the plurality of openings of the mesh electrode has an area of at least 0.28 mm 2 or at least 0.79 mm 2 .

4. The vacuum cleaner head according to claim 2 or 3, wherein, the conductive frame of the mesh electrode is composed of multiple strands defining the openings, and the maximum thickness of each strand is 1 mm or less.

5. The vacuum cleaner head according to any one of claims 2 to 4, wherein, each of the plurality of openings of the mesh electrode is polygonal.

6. The vacuum cleaner head according to any one of the preceding claims, wherein, the electrode is connectable to a power source to generate a potential difference and / or a voltage gradient between the electrode and the surface to be cleaned, thereby generating an electrostatic field.

7. The vacuum cleaner head according to claim 6, wherein, the polarity and / or the magnitude of the generated potential difference varies with time.

8. The vacuum cleaner head according to claim 6 or 7, wherein, the ratio of the generated potential difference to the distance between the electrode and the surface to be cleaned is 3 MV / m or less.

9. The vacuum cleaner head according to any one of claims 6 to 8, wherein, the generated potential difference is in the range of 1 kV to 10 kV.

10. The vacuum cleaner head according to claim 9, wherein, the generated potential difference is 6 kV or less, 4 kV or less, 2.6 kV or less, and / or 2.5 kV or less.

11. The vacuum cleaner head according to any one of the preceding claims, wherein, the electrode is mounted near a surface engaging portion of the vacuum cleaner head such that, in use, the distance between the electrode plane and the surface to be cleaned is 5 cm or less.

12. The vacuum cleaner head according to any one of the preceding claims, wherein, the electrode plane is angled relative to the surface to be cleaned to create a gradient within the electrostatic field.

13. A vacuum cleaner, comprising: a vacuum motor for driving an intake air flow; and a vacuum cleaner head according to any one of the preceding claims, which is connected to the intake air flow.

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