Heater assembly

Abstract

A heater assembly for a haircare appliance comprising an air duct defining an air flow path extending from an upstream end to a downstream end; a first heater element positioned in the flow path, the first heater element having a first electrical path defined between cutouts in a first sheet, the air flow path extending through the cutouts; and a second heater element positioned in the flow path downstream of the first heater element, the second heater element having a second electrical path defined between cutouts in a second sheet, the air flow path extending through the cutouts. The thickness of the first sheet is different to the thickness of the second sheet.

Description

Technical Field

[0001] A heater assembly for hair care appliances (such as hair dryers) typically uses a heater element made of a loop or spiral coil of one or more corrugated wires. Background Technology

[0002] An electric current passes through a conductor, heating it and thus heating the air flowing through it. However, this type of heater has several drawbacks. For example, the conductor is typically supported in the airflow path by mica supports, but these supports can impede airflow, leading to uneven heating. Furthermore, the conductor is of a fixed diameter, meaning that each part of a heater element, or every part of each heater element, made of conductor, has the same cross-sectional area in the direction of the current. This means that every part of the heating element experiences the same degree of electrical heating. However, parts of the heater element located downstream of other parts of the heater element (whether the same or different heater elements) experience less cooling because the air passing through them has already been heated. Similarly, parts of the heater element in “dead zones” in the airflow path (e.g., possibly caused by support structures) experience less cooling because the air flows through them at a lower speed. Parts that receive less cooling from the air may fail due to overheating, even if the conditions (e.g., the delivered electrical power and overall airflow) are satisfactory for the entire heater element. In many cases, the only practical way to mitigate this failure is to reduce the electrical power delivered to the entire heater assembly, which reduces the heater assembly’s ability to perform its function. Summary of the Invention

[0003] The object of the present invention is to mitigate or eliminate at least one of the above-mentioned disadvantages, or to provide an improved or alternative heater assembly.

[0004] According to a first aspect of the invention, a heater assembly for a hair care appliance is provided, the heater assembly comprising:

[0005] An air duct defines the airflow path extending from the upstream end to the downstream end;

[0006] A first heater element, positioned in a flow path, has a first electrical path defined between slits in a first sheet, and an airflow path extending through the slits; and

[0007] A second heater element, positioned downstream of the first heater element in a flow path, has a second electrical path defined between slits in the second sheet, through which an airflow path extends.

[0008] The thickness of the first sheet is different from the thickness of the second sheet.

[0009] The electrical path of a heater element formed from sheet material can be controlled in shape, which is not possible when the electrical path is formed from wire. For example, the electrical path can branch, turn at angles that are sharper than the angle at which a wire can bend, and / or have protrusions through which the electrical path can be supported, thereby eliminating the need for a separate support structure that would further impede airflow.

[0010] The different thicknesses of the sheets mean that, all else being equal, the first and second electrical paths have different cross-sectional areas in the direction of current flow. This, in turn, means that if the same electrical power is applied, the heating elements will heat at different rates and may reach different maximum temperatures before failing due to overheating. Therefore, the heating performance and / or resilience to failure of different heating elements can be customized (e.g., depending on the location of the different heating elements within the airflow path).

[0011] The second sheet can be thicker than the first sheet.

[0012] The second heating element, located downstream of the first heating element, will be positioned in hotter air and is therefore more likely to overheat. By making the second sheet thicker than the first sheet, the second heating element can be more resistant to overheating, all other things being equal (as mentioned above, due to the larger cross-sectional area of ​​the second electrical path in the direction of current). On the other hand, the first heater can remain thinner because it is in cooler air during use, thus maintaining its ability to heat air rapidly.

[0013] The heater assembly may also include a third heater element positioned in a flow path downstream of the second heater element, the third heater element having a third electrical path defined between slits in a third sheet, through which an airflow path extends.

[0014] A heater assembly with two or more heater elements can allow for greater heating effect and / or allow for more gradual heating of air.

[0015] The third sheet can be thicker than the second sheet.

[0016] This amplifies the advantage discussed above regarding the second sheet being thicker than the first sheet.

[0017] Each sheet is preferably no more than 2 mm thick, for example, no more than 1 mm thick or no more than 0.5 mm thick.

[0018] This relatively thin sheet can provide a relatively small cross-sectional area for the electrical path in the direction of current (all other things being equal), which can result in relatively high heating performance of the heater element.

[0019] Each sheet is preferably not less than 0.005 mm thick, for example, not less than 0.01 mm thick or not less than 0.03 mm thick.

[0020] This allows the heating element to be thick enough to withstand pre- and post-assembly processing, better resist damage from exposure to high-speed airflow during use, and / or make it easier or cheaper to manufacture.

[0021] The cutouts in each of the electrical paths can be formed by etching.

[0022] The use of etching can advantageously impose very few constraints on the shape of the heating element.

[0023] As an alternative, the cut can be formed by any other suitable manufacturing technique, such as stamping, waterjet cutting, or laser cutting.

[0024] Each of the electrical paths may have a generally dome shape.

[0025] A roughly dome-shaped electrical path ensures that the electrical path bends in a predictable direction during thermal expansion. Conversely, if the electrical path were flat, two adjacent electrical paths could bend in opposite directions during thermal expansion, potentially contacting each other and causing a short circuit. Conversely, or similarly, a dome-shaped electrical path is more resistant to deformation under the influence of high-speed airflow in the airflow path, much like how an arched bridge is more resistant to deformation under the weight of passing vehicles / pedestrians than a simply flat bridge.

[0026] Instead of a dome shape or any other shape, each of the electrical paths is generally flat.

[0027] This makes the electrical path advantageously easy to manufacture and allows the heater elements, and thus the heater assembly as a whole, to be advantageously compact.

[0028] Air ducts can be formed by stacking annular elements, each annular element defining an axial portion of the air duct.

[0029] This allows for greater customization of the heater assembly, enabling the creation of flow paths of varying lengths for different applications by utilizing different numbers of annular elements.

[0030] As an alternative, the flow path can be formed as a single piece. Alternatively, the flow path can be formed by an array of circumferential segments.

[0031] Each heater element can be embedded within a corresponding one of the annular elements.

[0032] For example, each heater element may have an annular element overlaid thereon.

[0033] Each heater element embedded in the ring element can be handled, for example, during assembly or inspection, thereby reducing the risk of damage.

[0034] As an alternative, each heater element can be sandwiched between a pair of annular elements.

[0035] One of the annular elements may form a spacer between adjacent heater elements.

[0036] This allows for more efficient mixing of the flow between adjacent heater elements, resulting in more uniform heating of the air in the airflow path.

[0037] The spacer can support a temperature sensor (e.g., a thermocouple) in the flow path. This allows for monitoring of the heating process before it is complete, which in turn allows for adjustment of the electrical power supplied to the heater element downstream of the spacer. For example, if the temperature sensor detects that the air is abnormally hot at that point in the flow path, it can signal the controller to reduce the electrical power delivered to the downstream heater element, thereby reducing its heating effect and preventing the air from leaving the flow path at excessively high temperatures.

[0038] The electrical path of each heater element can be located almost entirely within the airflow path.

[0039] This allows the heating element to be heated to temperatures higher than might be achieved if most of the electrical path were shielded from the cooling effect of air in the airflow path (e.g., by embedding it in a ring-shaped element).

[0040] At least two adjacent electrical paths may be spaced no more than 10 mm apart, for example, no more than 5 mm or no more than 3 mm apart.

[0041] This allows for a more compact heater assembly.

[0042] Each electrical path may be spaced at least 0.5 mm from its adjacent electrical path, for example, at least 1 mm or at least 1.5 mm. This reduces the risk of contact between adjacent electrical paths and the potential for short circuits or damage to each other.

[0043] The air duct can be approximately circular in cross-section, such as slightly oval, elliptical, or racetrack-shaped, or precisely circular. This makes it easier to install the heater assembly inside the handle of the hair care appliance while maintaining the largest possible cross-section for airflow path.

[0044] Each heater element can be made of metal and directly exposed to the air in the airflow path. This maximizes heat transfer between the heater element and the air in the airflow path, in contrast to arrangements where the metal is shielded from direct contact with the air (e.g., through an electrically insulating coating).

[0045] Metals that can be used to make heater elements include, for example, stainless steel, NiChrom, Inconel, tin, Hastelloy B or C and Nimonic 115.

[0046] The first electrical path may have a first width, and the second electrical path may have a corresponding second width that is different from the first width.

[0047] The first and second electrical paths having different thicknesses mean that, all other things being equal, they have different cross-sectional areas in the direction of current flow. This, in turn, means that if the same electrical power is applied, the heating elements will heat at different rates and may reach different maximum temperatures before failing due to overheating. Therefore, the heating performance and / or resilience to failure of different heating elements can be customized (e.g., depending on the location of the different heating elements within the airflow path).

[0048] The first width of the first electrical path may be narrower than the second width of the second electrical path.

[0049] The second heater element, located downstream of the first heater element, will be positioned in hotter air and is therefore more likely to overheat. By making the second electrical path wider than the first electrical path, the second heating element can be more resistant to overheating, all other things being equal (as mentioned above, due to the larger cross-sectional area of ​​the second electrical path in the direction of current). On the other hand, the first heater can remain narrower because it is in cooler air during use, thus maintaining its ability to heat air rapidly.

[0050] Each of the widths is preferably no more than 2 mm, for example no more than 1 mm or no more than 0.6 mm.

[0051] This relatively narrow electrical path can provide a relatively small cross-sectional area for the electrical path in the direction of current (all other things being equal), which can result in relatively high heating performance of the heater element.

[0052] Each of the widths may be no less than 0.05 mm, for example, no less than 0.1 mm or no less than 0.2 mm.

[0053] This allows the electrical paths to be thick enough to withstand pre- and post-assembly processing, better resist damage from exposure to high-speed airflow during use, and / or be easier or cheaper to manufacture.

[0054] Optional:

[0055] The heater assembly includes circuitry for connecting to a power source;

[0056] The first electrical path and the second electrical path are provided in the corresponding first circuit branch and second circuit branch; and

[0057] The first circuit branch and the second circuit branch are connected in parallel within the circuit.

[0058] To avoid ambiguity, the term "circuit branches connected in electrical parallel" as used herein refers to circuit branches that define separate paths for current, rather than a single electrical path passing through a series connection of two circuit branches. This term is not intended to imply that circuit branches are joined to each other at any particular electrical or spatial location.

[0059] With the first and second electrical paths connected in parallel, their influence on each other can be minimized. For example, the two electrical paths can be supplied with different voltages and / or currents, which would be impossible if they were connected in series. As another example, one or both of the first and second heating elements can be disconnected from the power source (e.g., via an electrical or mechanical switch) without having to disconnect the other.

[0060] Within the corresponding circuit branch, one of the heater elements can be connected in series with another heater element.

[0061] This increases the resistance of the circuit branch in question, thereby preventing overload of individual heating elements without requiring more complex circuitry or the power waste that would occur, for example, if resistors were used instead of other heating elements. Alternatively or similarly, connecting some heating elements in series can reduce the amount of wiring required compared to having all heating elements in parallel, which can reduce the overall cost, complexity, and / or assembly time of the heater assembly.

[0062] Alternatively or similarly, additional heater elements may be provided in other circuit branches.

[0063] Within the corresponding circuit branch, each of the heater elements can be connected in series with another corresponding heater element.

[0064] This can further enhance the benefits discussed above.

[0065] The circuit may include a power control component arranged to supply different voltages and / or currents to different circuit branches.

[0066] This allows the electrical power supplied to different heater elements to be tailored to their specific requirements. For example, a heating element with a relatively narrow electrical path can be supplied with less electrical power to combat potential overheating, or a heater element at the upstream end can be supplied with more electrical power because it will be cooled more by the air in the airflow path and is therefore less likely to overheat.

[0067] According to a second aspect of the invention, a hair care appliance is provided that includes a heater assembly according to a first aspect of the invention. Attached Figure Description

[0068] The invention will now be described with reference to the accompanying drawings, in which:

[0069] Figure 1 This is a perspective view of a portion of a heater assembly according to a first embodiment of the present invention;

[0070] Figure 2 yes Figure 1 A perspective view of a portion of the heater assembly and the heater element shown;

[0071] Figure 3 yes Figure 2 Cross-sectional views of the annular element and the heater element;

[0072] Figure 4 yes Figure 1 A perspective view of a portion of the spacer of the heater assembly shown;

[0073] Figure 5 It includes Figure 1 Electrical schematic diagram of part of the heater assembly shown;

[0074] Figure 6 This is a perspective view of a portion of a heater assembly according to a second embodiment of the present invention;

[0075] Figure 7 It includes Figure 6 An electrical schematic diagram of a portion of the heater assembly shown; and

[0076] Figure 8 This is a perspective view of a hair dryer, which may include... Figures 1 to 5 or Figure 6 and Figure 7 heater assembly.

[0077] Throughout the specification and all accompanying drawings, corresponding reference numerals denote corresponding features. Detailed Implementation

[0078] Figure 1A portion 2 of a heater assembly according to a first embodiment of the invention is shown. The heater assembly has an air duct 4 that defines an airflow path 6 extending through it from an upstream end 8 to a downstream end 10. The air duct 4 is composed of a stack of annular elements 12a, 12b, 12c, wherein each annular element defines a (relatively short) axial portion of the air duct 4.

[0079] In this specific embodiment, the air duct 4 is generally circular in cross-section, having a pair of flat edges 14, which gives it a slight racetrack shape. Each of the annular elements 12a-12c has a corresponding cross-sectional shape. In this embodiment, each of the annular elements 12a-12c, and therefore the entire air duct 4, is made of a liquid crystal polymer.

[0080] Each of the annular elements 12a supports a heater element 20, wherein any one of the heater elements can be considered a "first heater element" in the sense of the invention. In this embodiment, since the annular element 12a has been overmolded on top of its heater element 20, each annular element 12a has a heater element 20 embedded therein. Figure 2 and Figure 3 One of the annular elements 12a with its heater element 20 is shown, and each of the other heater elements 20 in the other annular elements 12a has the same shape.

[0081] In this embodiment, each heater element 20 is formed entirely from a bare metal sheet 22, wherein a set of cutouts 24 have been etched. Each heater element includes a pair of contact tabs 26 for connection to a power source via a controller as described later. An electrical path 30 is defined between the cutouts 24 such that it extends in a zigzag pattern between the two contact tabs 26.

[0082] Extending from each vertex of the sawtooth electrical path 30 is a support structure 32, which has a thin bridge 34 terminating in an hourglass-shaped support piece 36. Contact pieces 26 and support pieces 36 surround the electrical path 30 and are embedded within an annular element 12a. This allows the electrical path 30 to be fully positioned within the airflow path 6. The contact pieces 26 also protrude outward beyond the annular element 12a so that they can be connected to the circuit as described later.

[0083] To avoid ambiguity, during use, the thin bridges 34 may experience a small current flow. However, it should be understood that this current flow will be minimal and its effect on the overall heater element 20 is negligible. Therefore, they are not considered part of the electrical path 30.

[0084] As described above, in this embodiment, the sheet 22 forming the electrical path 30 (and indeed the entire heater element 20) is flat. Therefore, the electrical path 30, and indeed the entire heater element 20, is also flat. In this case, the heater element 20 (and thus the electrical path 30) is positioned perpendicular to the airflow path 6.

[0085] The heater elements 20 embedded in the annular element 12c (any one of which can constitute a "second heater element" within the sense of the invention) have substantially the same shape and construction as the annular element 12a. However, the heater elements 20 of each annular element 12a are formed from a sheet with a thickness of 0.1 mm, and the electrical path 30 of each of these heater elements is 0.3 mm wide. In contrast, the heater elements 20 of each annular element 12c are formed from a sheet with a thickness of 0.3 mm, and the electrical path 30 of each of these heater elements is 0.4 mm wide. Therefore, the electrical path 30 of the heater elements 20 of the annular element 12c has a larger cross-sectional area in the current direction than that of the heater elements 20 of the annular element 12a. Consequently, those heater elements 20 further downstream in the airflow path 6 undergo less electrical heating.

[0086] In this embodiment, the thickness (in the axial direction) of the annular element 12a is chosen such that within a group of heater elements 20 supported by these annular elements, the electrical path 30 of each heater element 20 is spaced 2 mm from its adjacent electrical path 30. Similarly, the thickness of the annular element 12c is chosen such that within a group of heater elements 20 supported by these annular elements, the electrical path 30 of each heater element 20 is spaced 2 mm from its adjacent electrical path 30. In some cases, this spacing may be the optimal trade-off, where the electrical paths 30 are packed relatively tightly together for compactness, but spaced far enough apart to prevent them from contacting each other after bending due to thermal expansion. As mentioned above, the electrical paths 30 (and indeed the entire heater element 20) of this embodiment are made of metal and are directly exposed to the airflow in the airflow path 6. Therefore, it is particularly important that the electrical paths 30 do not contact each other, as the lack of an insulating coating means that contact between them would result in a short circuit.

[0087] Although the electrical paths 30 of a group of heater elements 20 supported by annular element 12a are spaced 2 mm apart, and the same applies to the electrical paths 30 of a group of heater elements 20 supported by annular element 12c, the electrical path 30 of the downstream heater element 20 supported by annular element 12a is spaced 6 mm apart from the electrical path 30 of the upstream heater element 20 supported by annular element 12c. This is due to annular element 12b, which forms a spacer between the two heater elements 20 (and in this embodiment, between their respective annular elements 12a, 12c). In this embodiment, spacer 12b supports a temperature sensor in the form of a thermocouple 38 within the airflow path 6, the purpose of which will be discussed later.

[0088] Figure 1 The diagram shows portion 2 of the heater assembly connected to a circuit, which in turn can be connected to a power source such as a battery or a power supply. The electrical schematic of the heater assembly 50 shows circuit 52, as shown... Figure 5 As shown. Circuit 52 has a controller 54, which has a terminal 56 for connection to a power source (not shown), and a first circuit branch and a second circuit branch 58a, 58c arranged in electrical parallel, through which electrical power from the power source can be supplied to the heater element 20.

[0089] The first circuit branch 58a includes each of the heater elements 20 supported by the ring element 12a, and these heater elements 20 are connected in series with each other. Therefore, one or more of these heater elements 20 may constitute an "additional heater element" within the scope of this invention. The second circuit branch 58c includes each of the heater elements 20 supported by the ring element 12c, and these heater elements 20 are connected in series with each other. Alternatively or similarly, one or more of these heater elements 20 may constitute an "additional heater element" within the scope of this invention.

[0090] As described above, the two circuit branches 58a and 58c are connected in parallel. Each circuit branch 58a and 58c has a corresponding set of power control components 60a and 60c, which can supply electrical power to the corresponding branch. In this case, the power control component 60a is configured to supply a higher voltage to the first circuit branch 58a than the voltage supplied to the second circuit branch 58c by the power control component 60b.

[0091] The controller 54 is also connected to the thermocouple 38 and the switch 62 located in the second circuit branch 58c. In use, after air passes through the heater element 20 supported by the annular element 12a, the controller monitors its temperature, and if the temperature exceeds a threshold, the controller 54 opens the switch 62 to disconnect the heater element 20 supported by the annular element 12c and prevent any further heating from occurring.

[0092] Figure 6 and Figure 7 A heater assembly 50 according to a second embodiment of the present invention is shown. The second embodiment is similar to the first embodiment, so only the differences are described.

[0093] While the first embodiment utilizes two heater elements 20 of different sizes, namely a heater element supported by an annular element 12a and a heater element supported by an annular element 12c, the second embodiment utilizes four heater elements 20 of different sizes, namely a heater element supported by an annular element 12a, a heater element supported by an annular element 12c, a heater element supported by an annular element 12e, and a heater element supported by an annular element 12f. In this embodiment, the heater elements 20 supported by annular elements 12a, 12c, 12e, and 12f have electrical paths 30 formed from sheets of 0.05mm, 0.1mm, 0.2mm, and 0.3mm, respectively, and the widths of these electrical paths are 0.25mm, 0.35mm, 0.4mm, and 0.45mm, respectively.

[0094] According to the above convention, any one of the heater elements 20 supported by the annular element 12a can constitute a "first heater element," and any one of the heater elements 20 supported by the annular element 12c can constitute a "second heater element." Therefore, any one of the heater elements 20 supported by the annular element 12e can constitute a "third heater element" according to the invention. However, to avoid doubt, any one of the heater elements 20 supported by the annular element 12f can constitute a "third heater element." Furthermore, it is also possible that one of the heater elements 20 supported by the annular element 12c constitutes a "first heater element," one of the heater elements 20 supported by the annular element 12e constitutes a "second heater element," and the heater elements 20 supported by the annular element 12f constitute a "third heater element."

[0095] The second embodiment also differs from the first embodiment in that there are two spacers 12b supporting the thermocouples 38 and another spacer 12d, which separates the heater elements 20 (and their respective annular elements 12c, 12d) on both sides to smooth the flow, but does not support any part of the airflow path 6.

[0096] The circuit 52 of the second embodiment has four circuit branches 58a, 58c, 58e, and 58f, each with a corresponding power control unit 60a, 60c, 60e, and 60f, wherein heater elements 20, supported by ring elements 12am, 12cm, 12e, and 12f respectively, are connected in series. In this case, the power control units 60c, 60e, and 60f are configured to be actively managed by the controller to adjust the voltage supplied to the circuit branches 58c, 58e, and 58f corresponding to each power control unit based on feedback from the two thermocouples 38, so as to provide the smoothest heating along the length of the airflow path 6.

[0097] Figure 8 A hair care appliance in the form of a hair dryer 70 is shown, which may include a heater assembly 50 according to one of the above embodiments of the invention. The hair dryer 12 has a cylindrical handle 72 with an air inlet 74 at its base, above which is a motor-driven fan (not visible) for drawing air through the hair dryer. The upper portion 76 of the handle 72 may include the heater assembly 50, through which hot air is ducted and enters the head 78 of the hair dryer, then exits through an annular outlet 80 at the front of the head. A power cord (not shown) extends upward into the bottom of the handle 72 to provide mains power to the hair dryer for driving the motor-driven fan (not visible) and powering the heater assembly 50.

[0098] It will be understood that various modifications can be made to the above embodiments without departing from the scope of the invention as defined by the appended claims. For example, the electrical path of one or more heater elements may be dome-shaped rather than purely flat, due to its formation between cuts in the dome sheet. The dome-shaped electrical path may, for example, protrude slightly in the upstream direction along the flow path. As another example, the air duct (and heater element) may be square, hexagonal, or octagonal in cross-section rather than generally circular.

[0099] To avoid ambiguity, although the associated circuitry has been described as part of the heater assembly forming the first and second embodiments, in other embodiments the necessary circuitry may be provided separately.

Claims

1. A heater assembly for a hair care device, the heater assembly comprising: An air duct defines the airflow path extending from the upstream end to the downstream end; A first heater element is positioned in a flow path, the first heater element having a first electrical path defined between cuts in a first sheet, the air flow path extending through the cuts; as well as A second heater element, positioned downstream of the first heater element in a flow path, has a second electrical path defined between slits in the second sheet, the airflow path extending through the slits. The thickness of the first sheet is different from the thickness of the second sheet.

2. The heater assembly of claim 1, wherein the second sheet is thicker than the first sheet.

3. The heater assembly of claim 1, further comprising a third heater element positioned downstream of the second heater element in the flow path, the third heater element having a third electrical path defined between slits in a third sheet, the airflow path extending through the slits.

4. The heater assembly of claim 3, wherein the third sheet is thicker than the second sheet.

5. The heater assembly according to any one of the preceding claims, wherein the thickness of each of the sheets does not exceed 1 mm.

6. The heater assembly according to any one of the preceding claims, wherein the thickness of each of the sheets is not less than 0.01 mm.

7. The heater assembly according to any one of the preceding claims, wherein the cutouts in each of the electrical paths are formed by etching.

8. The heater assembly according to any one of the preceding claims, wherein each of the electrical paths has a generally dome shape.

9. The heater assembly according to any one of the preceding claims, wherein each of the electrical paths is substantially flat.

10. The heater assembly according to any one of the preceding claims, wherein the air conduit is formed by a stack of annular elements, each of the annular elements defining an axial portion of the air conduit.

11. The heater assembly of claim 10, wherein each heater element is embedded within a corresponding one of the annular elements.

12. The heater assembly of claim 10 or 11, wherein one of the annular elements forms a spacer between adjacent heater elements.

13. The heater assembly according to any one of the preceding claims, wherein the electrical path of each heater element is substantially entirely located within the airflow path.

14. The heater assembly according to any one of the preceding claims, wherein at least two adjacent electrical paths are spaced no more than 5 mm apart.

15. A hair care appliance comprising a heater assembly according to any one of the preceding claims.

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