GB2615141A

GB2615141A - Flow heaters and liquid heating appliances

Info

Publication number: GB2615141A
Application number: GB2201285.0A
Authority: GB
Inventors: Peter Moughton Colin; Howitt James; Robert Morris Dean
Original assignee: Strix Ltd
Current assignee: Strix Ltd
Priority date: 2022-02-01
Filing date: 2022-02-01
Publication date: 2023-08-02
Anticipated expiration: 2042-02-01
Also published as: GB2615141B; GB202201285D0; WO2023148482A1

Abstract

A flow heater 2, for heating a liquid (preferably water) comprises a heating chamber 4, liquid inlet 12 and outlet 14. A heating element 32 is positioned within the heating chamber. The heating chamber comprises a channel 40 through which liquid flows and a portion 34 of the heating element lies within the channel. The channel is shaped by the outer wall of heating chamber and a protrusion 38, which corresponds to the portion of the heating element within the channel. The heating element and the protrusion may have corresponding shapes. The protrusion may have a sloped portion 50 with liquid falling on the sloped portion. Preferably, the flow heater has an expansion space arranged above the channel. The heating chamber may comprise a steam outlet (62, Fig 9) at a level higher than the liquid outlet. An outlet 44 and inlet 42 temperature sensor may be included. Preferably a control arrangement 16 cuts a power supply to the heating element when a pre-set temperature is detected. Preferably a pump (184, Fig 11) drives the liquid into the heating chamber. A liquid heating appliance is also claimed, preferably with a liquid reservoir.

Description

Flow Heaters and Liquid Heating Appliances The present application relates to flow heaters for heating a liquid flowing therethrough, and to liquid heating appliances comprising such flow heaters.

Flow heaters can be used to heat a liquid flowing therethrough, often to a pre-set temperature. Such flow heaters can be used to deliver small quantities of heated liquid very quickly and may thus be used to heat liquid on demand. Flow heaters are often used in domestic liquid heating appliances wherein a relatively small volume of heated liquid is required. For example, flow heaters can be used in domestic water heating appliances which are used to provide a single cup of hot water for making a beverage. Users of such domestic appliances generally have an expectation that the appliance, specifically the flow heater contained therein, will heat the water to the desired temperature in a relatively short period of time. Accordingly, flow heaters typically comprise a number of purpose-built components designed specifically for use with the flow heater in order to achieve the desired heating in the required time.

The present invention aims to provide an improved flow heater and when viewed from a first aspect provides a flow heater, for heating a liquid flowing therethrough, comprising: a heating chamber which comprises a liquid inlet through which the liquid enters the heating chamber and a liquid outlet through which heated liquid exits the heating chamber; a heating element arranged within heating chamber and positioned so as to contact and heat the liquid flowing through the heating chamber during use of the flow heater; wherein the heating chamber comprises a channel through which liquid flows in use, wherein a portion of the heating element is arranged within the channel, and wherein the channel has a shape which corresponds to the portion of the heating element which is arranged within the channel.

The Applicant has recognised that by having a channel with a shape which corresponds to the portion of the heating element within the channel, may advantageously limit the volume of liquid which is contained within the heating chamber, specifically the amount of liquid which is contained and heated within the channel. Reducing the volume of liquid which is contained and heated within the heating chamber may help to ensure that all, or substantially all, of the liquid within the heating chamber is heated to the desired temperature. The channel with a shape which corresponds to the portion of the heating element arranged therein may also act to constrain the liquid which is being heated such that it is kept in relatively close proximity to the heating element. This may help to ensure that the liquid can be heated quickly and efficiently. The channel may be considered to have a shape which conforms to the portion of the heating element which is within the channel.

The portion of the heating element which is arranged within the channel will be in contact with the liquid flowing through the channel, during use of the flow heater. The heating element may comprise further portions which do not contact liquid within the chamber during typical use. For example, the further portions may extend away from the portion of the heating element contained within the chamber, to an open space within the heating chamber which does not become filled with liquid during typical operation.

The channel through which liquid flows during use of the flow heater may not necessarily be completely enclosed and may thus form an open channel. For example, the heating chamber may comprise an open space arranged above the channel. The channel may be formed at the bottom of the heating chamber, with the open space arranged above the channel. The liquid inlet may be arranged on an upper portion of the heating chamber and liquid may pass, e.g. fall, through the open space before reaching the channel through which it flows and in which it is heated. The flow heater may be configured, for example by appropriate arrangement of the liquid outlet, such that the liquid which passes into the heating chamber does not fill the open space above the channel. For example, the liquid outlet may be aligned with an upper level of the channel such that when the liquid fills the channel and passes out through the liquid outlet before it can fill the open space above the channel. In other embodiments, the channel may define the entire 3 -heating chamber such that there is no open space which is not filled by liquid during use.

During use, liquid may flow through the liquid inlet, into the heating chamber and into the channel. The liquid may then flow through the channel, whilst being heated by the portion of the heating element arranged within the channel, before passing out of the liquid outlet.

Any suitable heating element, having any shape, may be used within the flow heater. As such, the heating chamber, specifically the channel thereof, may have any suitable shape. For example, in embodiments wherein the portion of the heating element within the channel is straight, the channel may have a corresponding straight shape. Similarly, the heating element may comprise multiple portions which are arranged within the channel and each portion may have a different shape. As such, the channel may comprise corresponding portions, each of which have a corresponding shape to the respective portion of the heating element.

The Applicant has recognised that some heating elements which may be used within the flow heater, may be shaped such that they define a void, in which no portion of the heating element is present. For example, the heating element may generally extend to define a circular shape which comprises a circular-shaped void, for example at its centre. As will be appreciated by those skilled in the art, with such circular shaped heating elements, any liquid which passes within the void may be heated to a lesser amount, compared to liquid which is closer to the heating element itself. This may result in portions of liquid which are not heated to the intended temperature. Accordingly, in a set of embodiments, the heating chamber comprises a protrusion extending into the heating chamber such that the channel extends around the protrusion; the heating element comprises a void; and the heating element is arranged within the heating chamber such that the protrusion extends into the void.

The protrusion may therefore act to fill, or at least partially fill, the void, thereby substantially preventing liquid from residing within the void. As a result, the channel may have a shape which closely corresponds to the heating element, including the 4 -shape defined by its void. This may advantageously result in a reduction of cold spots, i.e. spaces within the heating chamber where the liquid is not heated. The protrusion may also act to reduce the volume of liquid which is contained within the channel within the heating chamber. This arrangement may thus improve the heating of the liquid flowing through the heating chamber. The channel may be delimited by the protrusion and a wall, e.g. an outer wall, of the heating chamber. The wall may comprise a base and side wall of the heating chamber. The channel may surround, or at least partially surround, the protrusion.

The protrusion may extend from any suitable part within the heating chamber. In some embodiments, the heating chamber may be defined by a main housing and a cover. In some embodiments, the protrusion may extend from an upper wall of the heating chamber, e.g from a cover of the heating chamber. In a set of embodiments, however, the protrusion extends from a main housing of the heating chamber. For example, the protrusion may extend from a base of the main housing.

Having a protrusion which extends from the base of the main housing may advantageously minimise the amount of material required to form the protrusion, as the protrusion may only be raised from the base of the main housing to the height of the liquid level within the heating chamber. This is compared to having the protrusion extend downwards, for example from a cover of the heating chamber, whereby at least part of the protrusion may extend through a space in which no liquid is present during use of the flow heater. Additionally, having a protrusion extend downward from a cover of the heating chamber may result in a small void, between the base of the protrusion and floor of the heating chamber, where liquid may collect and pose a risk of forming mould. As will be appreciated, having the protrusion extend from the base may remove any such void and thus reduce the likelihood of the build-up of mould within the heating chamber.

In some embodiments, the protrusion may be integrally formed with the base of the heating chamber. For example, the base of the heating chamber may be formed by injection moulding, and the protrusion may be an integral part of the injection moulded base. Integrally forming the protrusion with the base of the heating chamber may simplify manufacture of the flow heater.

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The protrusion may have any suitable shape which ads to at least partially occupy the void and reduce the volume of liquid received within the channel. In a set of embodiments, the shape of the protrusion corresponds to the shape of the void of the heating element. For example, if the heating element is shaped to define a square void, the protrusion may have a corresponding square shape. Similarly, if the heating element comprises a circular void, the protrusion may have a circular shape. However, it will be appreciated that the shape of the protrusion may not match the shape of the void exactly, but may nonetheless be considered to have a corresponding shape. For example, an elliptical protrusion may be considered to have a shape which corresponds to a circular void, as both the elliptical protrusion and the circular void are rounded shapes. By having a corresponding shape, the protrusion may occupy, i.e. fill, more of the void. The shape of the protrusion may be defined by its cross-section in a horizontal plane. The shape of the void may also be defined by its cross-section in a corresponding horizontal plane.

In a set of embodiments, the protrusion may occupy a substantial portion of the void. In a set of embodiments, the protrusion occupies at least 20 %, e.g. at least 25 %, e.g. at least 30 %, e.g. at least 40 %, e.g. at least 45 %, e.g. at least 50 % of the void within the heating element. In occupying a significant portion of the void, the formation of cold spots may be reduced. Additionally, the protrusion may occupy a maximum amount of the void whilst avoiding the heating element burning or igniting the protrusion when the flow heater is operated without any liquid therein.

As mentioned previously, the heating element may have a void with any suitable shape, and the protrusion may have a void with a corresponding shape. In a set of embodiments, the heating element comprises a void which has a closed curve shape and wherein the protrusion has a corresponding shape. The protrusion may thus have a closed curve shape, however the shape of the closed curve of the protrusion may not be identical to the closed curve shape of the void. For example, the protrusion may have a closed curve shape in the form of an ellipse, whereas the void may have a closed curve shape in the form of a circle. Nonetheless, by having two generally corresponding shapes, the volume of liquid being heated may be kept to a minimum, and the liquid may remain relatively close to the heating element and thus be heated quickly. The formation of cold spots may also be avoided. 6 -

In a set of embodiments, at least the portion of the heating element within the channel has a curved profile which defines a substantially circular-shaped void. The substantially circular-shaped void may comprise a circular-shaped void. The substantially circular-shaped void may be arranged at the centre of the heating element. In such embodiments, the protrusion may have a corresponding curved, e.g. circular or elliptical, shape. In such embodiments, the channel formed partially by the protrusion may be considered to form a ring-shaped or toroidal channel.

In another set of embodiments, at least the portion of the heating element in the channel has a spiral profile. A standard, for example off-the-shelf, spiral shaped heating element may thus be used within the flow heater. Using an off-the-shelf spiral heating element may keep the cost of the flow heater to a minimum. The spiral heating element may comprise a void, for example a circular-shaped void, for example located at its centre. In combination with the protrusion, the flow heater may have a channel which substantially corresponds to the shape of the heating element and thus heats the liquid flowing therethrough appropriately. As such, by using an off-the-shelf heating element with a channel shaped to correspond to the shape of the heating element, the cost of the flow heater may be kept to a minimum, whilst potentially achieving quick and efficient heating of the liquid flowing therethrough.

Depending on the specific form of the heating element, in some instances it may be advantageous to allow liquid to pass between the protrusion and the heating element, such that the liquid can be heated by a portion of the heating element which faces the protrusion. As such, the shape and size of the protrusion may correspond to the shape of the void whilst maintaining a spacing between the heating element and the protrusion. Such a spacing may also facilitate the insertion of the heating element into the heating chamber. Accordingly, in a set of embodiments, a minimum spacing between the protrusion and the heating element is at least 0.2 mm, e.g. at least 0.3 mm, e.g. at least 0.4 mm, e.g. 0.5 mm. The minimum spacing may also ensure that the flow heater operates safely. The Applicant has found that having a minimum spacing as set out above keeps the protrusion as close as possible to the heating element, without risk of it burning or igniting when the flow heater is operated without any liquid within it. The minimum spacing may represent the closest point of the heating element to the protrusion, 7 -and other parts of the heating element may be spaced from the protrusion by a larger amount.

As will be appreciated by those skilled in the art, the volume of the heating chamber may generally be kept as small as possible such that the flow heater occupies a relatively small space. This may advantageously mean that the flow heater occupies a relatively small amount of space within an appliance in which it is utilised, and therefore the size of appliance may also be reduced. However, the Applicant has recognised that reducing the volume of the heating chamber can create difficulties during the assembly of the flow heater. Specifically, the Applicant has recognised that having the heating chamber with a small volume, together with a channel which corresponds to the shape of the heating element and a protrusion, can make it difficult to insert the heating element into the heating chamber. Accordingly, in a set of embodiments, the heating chamber comprises a mounting portion for mounting the heating element within the heating chamber, and wherein the protrusion comprises a sloped portion which extends in a direction towards the mounting portion.

The mounting portion may, for example, comprise an opening in a wall of the heating chamber through which the heating element, or a component attached thereto, is passed into and fixed into place. The sloped portion may extend from a peak of the protrusion towards a base of the protrusion such that the protrusion comprises a peak which is narrower that its base. The sloped portion may increase the free-space within the heating chamber between the protrusion and the mounting portion and thereby provide more space for the insertion of the heating element.

This may facilitate the insertion of the heating element into the heating chamber.

The liquid inlet may introduce liquid into the heating chamber at any suitable location within the heating chamber. For example, the liquid inlet may be arranged on a base of the heating chamber. In a set of embodiments, however, the liquid inlet is arranged above the sloped portion such that liquid falls onto the sloped portion. Arranging the liquid inlet above the protrusion may advantageously mean that the liquid first contacts the sloped portion of the protrusion before reaching the channel, this may act to direct the liquid to the appropriate space of the channel.

The liquid inlet may be arranged at an opposite end of the heating chamber to the 8 -liquid outlet. As such, the liquid inlet may introduce liquid into the channel at one end or side of the channel, and the liquid outlet may be arranged at the opposite end or side of the channel.

As discussed previously, the heating element may have any suitable shape and form. The heating element may comprise a single length of heating element which extends within the channel. In another set of embodiments, the heating element comprises a first length of heating element and a second length of heating element, which is spaced from the first length of heating element, and wherein the first and second lengths of heating element extend together within the channel.

The presence of first and second lengths of heating element which extend together within the channel, i.e. multiple lengths of heating element which extend within the same channel, may advantageously increase the rate at which liquid can be heated within the channel. This may mean that the length of the channel can be reduced, which may make the overall size of the flow heater smaller. Each of the first and second lengths may be connected to one another such that they are each part of the same heating element. Each of the first and second lengths may follow any suitable profile. For example, each of the first and second lengths may be straight and may, for example, extend substantially parallel to one another. The first and second lengths may be joined by a connecting portion. The connecting portion may be curved. In this case, the first and second lengths, together with the connecting portion, may form a substantially U-shaped portion of heating element. The heating element may comprise further lengths of heating element which may extend within the channel.

In addition to the above, by having first and second lengths of heating element which are part of the same heating element, the two ends of the heating element may be proximal to one another. This may be particularly advantageous when the heating element is an electric heating element, e.g. a sheathed electrical heating element, as the electrical connections to the heating element may be proximal to one another, which may simplify the electrics within the flow heater, or indeed any appliance in which it is utilised. 9 -

Other forms of heating element may be considered to comprise first and second lengths of heating element and each of the first and second lengths of heating element may be curved, rather than straight. Taking a spiral-shaped heating element as an example, each circle of the spiral-shaped heating element may be considered to be a respective length of heating element, and thus the spiral-shaped heating element may be considered to be formed of multiple lengths of heating elements which are joined together. An arbitrary start point on the spiral may be selected, and a length may be considered to be the length of heating element from the start point until the heating element spirals back around to the start point.

The liquid outlet may be arranged in any suitable position within the heating chamber such that heated liquid can flow out of the liquid outlet. In a set of embodiments, the liquid outlet within the heating chamber is arranged at a level within the heating chamber which is higher than the portion of the heating element which extends within the channel.

The liquid outlet may be arranged such that liquid escapes when the liquid level within the heating chamber reaches the height of the liquid outlet. This liquid outlet may thus act as a weir. Arranging the liquid outlet at a level within the heating chamber which is higher than the portion of the heating element, which extends within the channel, may also advantageously mean that the entire portion of the heating element within the channel becomes immersed during operation of the flow heater. Accordingly, the entire portion of the heating element within the channel may contribute towards the heating of the liquid therein. This may help to quickly and efficiently heat the liquid in the channel. In embodiments which comprise a protrusion, the protrusion may extend within the heating chamber to a level which is higher than the liquid outlet. The liquid outlet may be arranged such that the liquid volume within the channel is at least 40 ml, e.g. at least 50 ml, e.g. at least 60 ml, e.g. 65 ml.

In some embodiments, the flow heater may be configured to heat the liquid flowing therethrough to boiling. As such, vapour, e.g. steam may be formed during heating of the liquid. Accordingly, in a set of embodiments, the flow heater further comprises an expansion space arranged above the channel. The expansion space may allow vapour, e.g. steam, to separate from the heated liquid. As discussed -10 -previously, the channel may comprise an open channel which allows steam to separate and pass into the expansion space, i.e. an open space, at any point along the channel. Alternatively, part of the channel may be enclosed, and only part of the channel may be exposed to the expansion space.

In a set of embodiments, the heating chamber further comprises a steam outlet, and wherein the steam outlet is arranged at a level which is higher than the liquid outlet. The steam outlet may allow steam to escape the heating chamber separately to the heated water. This may achieve a more laminar flow of liquid from the liquid outlet, which may be considered to be preferable by users of the flow heater. The steam outlet may also prevent the build-up of excessive pressure within the heating chamber.

The flow heater may be operated in any suitable manner to heat the liquid flowing therethrough. The flow heater may comprise a control means, e.g. a controller, configured to control operation of the flow heater. The control means may, for example, be used to control the temperature, flow rate and/or volume of liquid dispensed by the flow outer. Control of the flow heater may be based on a number of factors. In a set of embodiments, the flow heater further comprises an outlet temperature sensor positioned to measure the temperature of the liquid which flows out of the liquid outlet. The outlet temperature sensor may be arranged downstream of the liquid outlet and thus be sensitive to the temperature of the liquid which passes out through the liquid outlet. Alternatively, the outlet temperature sensor may be arranged upstream of the liquid outlet, for example just before the liquid outlet, so as to detect the temperature of the liquid flowing therethrough. The outlet temperature sensor may extend into the heating chamber and be in contact with the liquid flowing therethrough. The outlet temperature sensor may comprise a thermistor, for example a negative temperature coefficient (NTC) thermistor. Any control means provided to control operation of the flow heater may be operatively connected to the outlet temperature sensor.

In another set of embodiments, the flow heater further comprises an inlet temperature sensor positioned to measure the temperature of the liquid which flows into the heating chamber. The inlet temperature sensor may be located in any suitable position to measure the temperature of the liquid entering the heating chamber. The inlet temperature sensor may be arranged upstream of the liquid inlet, in order to measure the temperature of the liquid flowing through the liquid inlet. Alternatively, the inlet temperature sensor may be arranged downstream of the liquid inlet. For example, the inlet temperature sensor may be arranged within the heating chamber at a position at which the liquid enters the chamber. The inlet temperature sensor may comprise a thermistor, for example a negative temperature coefficient (NTC) thermistor. Similarly, any control means provided to control operation of the flow heater may be operatively connected to the inlet temperature sensor.

The flow heater may be operated based on the temperature(s) measured by the outlet temperature sensor and/or the inlet temperature sensor. For example, depending on the temperatures measured, the flow rate of liquid into the chamber and/or the operation of the heating element, e.g. its power or duty cycle, may be altered to achieve the output of liquid with a desired temperature.

In a set of embodiments, the flow heater further comprises a control arrangement mounted to the heating chamber and wherein the control arrangement is configured to cut a power supply to the heating element when a pre-set temperature is detected. The control arrangement may be a thermomechanical control arrangement. For example, the control arrangement may comprise a thermomechanical switch arranged to cut the power supply to the heating element when a pre-set temperature is detected. The control arrangement may be arranged to monitor a temperature of the heating chamber, or contents thereof, or monitor a temperature of the heating element. The thermomechanical control arrangement may be an off-the-shelf control arrangement, for example Strix's T34 control. Using an off-the-shelf control arrangement may once again keep the cost of the flow heater relatively low.

The pre-set temperature may be indicative of a 'dry-boil' operation, i.e. when the supply of liquid to the heating chamber is stopped with the heating element still receiving power. The control arrangement may comprise a temperature sensitive element, e.g. a thermomechanical switch, which is arranged in line with the liquid outlet such that when a liquid level drops below the level of the liquid outlet, and the -12 -heating element is receiving power, the temperature sensitive element will detect the pre-set temperature and cut the power supply to the heating element.

The heating element may comprise any element which is capable of heating the contents of the heating chamber. The heating element may comprise an electric heating element. The heating element may comprise a die-cast heating element. In a set of embodiments, the heating element comprises a sheathed electrical heating element. A sheathed electrical heating element may be produced at relatively low cost, and thus keep the cost of the flow heater relatively low. The sheathed electrical heating element may comprise an off-the-shelf sheathed electrical heating element. As the heating element sits within channel, which is filled with liquid during operation, the heating element may be considered to be an immersed heating element. Whilst in the embodiments above only a single heating element is described, the heating element may comprise multiple heating elements and the channel may conform to the shape of each of the multiple heating elements.

Liquid may pass into, through, and out of the heating chamber, by any suitable means. For example, liquid may flow through the heating chamber under gravitational pressure. In a set of embodiments, however, the flow heater further comprises a pump arranged to drive the liquid into the heating chamber. The use of a pump may advantageously provide more control over the flow of liquid into the heating chamber, and thus the flow of the liquid through and out of the heating chamber. This may allow for improved control over the temperature and/or flow rate of the liquid exiting the heating chamber via the liquid outlet.

The flow heater may be used to heat any suitable liquid which is capable of flowing therethrough. In a set of embodiments, the liquid comprises water.

The flow heater may also be configured to heat the liquid to any suitable temperature, which may depend on the application of the flow heater. In a set of embodiments, the flow heater is configured to heat the liquid therein such that the liquid leaving the liquid outlet is at least 80 °C, e.g. at least 90 °C, e.g. at least 95 °C, e.g. 100 °C. The flow heater may thus be capable of heating liquid to a temperature suitable for use in the preparation of hot beverages. The temperature -13 -to which the flow heater heats the liquid flowing therethrough may be adjustable. Adjustment of the temperature may be achieved, for example, by controlling the power of the heating element and/or the speed of the pump which may thereby affect the flow rate of the liquid through the flow heater.

The heating element may have any suitable heating power. Reducing the volume of liquid which is heated within the heating chamber, by having the shape of the water receiving chamber correspond to the heating element, may advantageously reduce the power of the heating element which is required to ensure appropriate operation of the flow heater. In a set of embodiments, the heating element has power of at least 1 kW, e.g. at least 1.5 kW, e.g. at least 2 kW, e.g. 2.2 kW.

In any of the embodiments described above, the heating chamber, specifically the channel thereof, may have any suitable orientation. For example, the channel may be arranged in a substantially horizontal orientation such that liquid flowing therethrough flows substantially horizontally through the channel. Alternatively, the channel may be arranged in a substantially vertical orientation such that liquid flowing therethrough flows substantially vertically through the channel. In some embodiments, the channel may comprise a first portion having a horizontal orientation and a second portion having a vertical orientation.

The flow heater according to any embodiment of the present invention may be used in any suitable application which requires liquid to be heated on demand. Therefore, according to a further aspect of the present invention there is provided a liquid heating appliance, for providing heated liquid on demand, comprising a flow heater according to any of the embodiments described above. The liquid heating appliance may be a domestic, e.g. countertop, appliance. The liquid heating appliance may be a water heating appliance.

The liquid heating appliance may be supplied with liquid in any suitable manner.

For example, the liquid heating appliance may be connected directly to a liquid, i.e. water, supply. In another set of embodiments, the liquid heating appliance comprises a liquid reservoir fluidly connected to the flow heater. As such, the liquid heating appliance may be movable, e.g. portable, and may be moved around, for example to different positions on a user's countertop.

-14 -Some preferred embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of a flow heater in accordance with an embodiment of the present invention; Fig. 2 shows a perspective view of the rear of the flow heater shown in Fig. 1; Fig. 3 shows a cut-away view of the flow heater to reveal the heating element therein; Fig. 4 shows a top-view of the flow heater with the cover removed therefrom; Fig. 5 shows an isometric view of the flow heater with the cover removed therefrom; Fig. 6 shows a side-on sectional view of the flow heater showing the protrusion extending within the heating element; Figs 7A-7C show the insertion of the heating element into the heating chamber during assembly of the flow heater; Fig. 8 shows a perspective view of the flow heater, with the cover removed, showing the liquid and steam outlets; Fig. 9 is a sectional view of the flow heater showing the steam outlet and liquid outlet; Fig. 10 is a perspective view of a liquid heating appliance in accordance with an embodiment of the present invention, whereby the appliance comprises the flow heater shown in earlier Figures; Fig. 11 is a cut-away view of the liquid heating appliance shown in Figure 10, so as to reveal the flow heater arranged therein; Fig. 12 shows a perspective view of a flow heater in accordance with another embodiment of the present invention; and Fig. 13 shows a view inside the uppermost part of the heating chamber of the flow heater shown in Fig. 12.

Figure 1 shows a perspective view of a flow heater 2 for heating a liquid flowing therethrough. The flow heater 2 comprises a heating chamber 4 in which liquid flowing therethrough is heated. The heating chamber 4 is defined by a main housing 5 which has an open top which is closed by a cover 6. The cover 6 comprises a series of holes 8 which are configured to align with corresponding holes 10 on the main housing 5. Suitable fixing means, e.g. screws, may be passed through the holes 8 and corresponding holes 10 to secure the cover 6 to the -15 -main housing 5, and thereby close the heating chamber 4. Of course any other fixing means may be used to secure the cover 6 to the main housing 5. For example, snap-fits operating between the cover 6 and main housing 5 may operate to secure the cover 6 in position. Whilst not visible in this Figure, a seal may be arranged between the cover 6 and the main housing 5 so as to seal the cover 6 to the main housing and thereby prevent the escape of liquid and/or steam from the joint between the cover 6 and main housing 5 of the heating chamber 4.

The flow heater 2 comprises a liquid inlet 12. In the embodiment depicted, the liquid inlet 12 is integrally provided with the cover 6 and provides an inlet for the heating chamber 4. The liquid inlet 12 may be integrally formed with the cover 6, for example as part of the moulding process when forming the cover 6. However, the liquid inlet 12 may be arranged in any other suitable position so as to introduce liquid into the main housing 5. A dispense outlet 14 is provided to allow the escape of both steam and heated liquid from the flow heater. This dispense outlet 14 will be described in more detail with reference to later Figures.

A control arrangement 16, is arranged on the rear of the main housing 4. As shown in later Figures, the control arrangement 16 supplies the heating element 32 (not visible in this Figure) with electrical power. The control arrangement 16 may comprise an overheat detection means arranged to detect overheating of the flow heater, for example when the heating element 32 is operated, but when the liquid volume within the heating chamber 4 is insufficient. The control arrangement 16 may, for example, comprise Strix's well known T34 series control.

Electrical leads 18 are connected to an inlet temperature sensor (not visible in this Figure) which is arranged to detect the temperature of liquid as it enters the main housing 4. Electrical leads 20 are connected to an outlet temperature sensor (not visible in this Figure) which is arranged to detect the temperature of liquid before it passes out through the liquid outlet (not shown in this Figure).

Figure 2 shows a perspective view of the rear of the flow heater 2. As depicted, the control arrangement 16 comprises a live electrical terminal 22, a neutral electrical terminal 24 and an earth terminal 26. The live electrical terminal 22, neutral electrical terminal 24 and earth terminal 26 may be connected to a suitable power -16 -supply, for example within a liquid heating appliance in which the flow heater 2 may be installed. The control arrangement 16 is attached to the heating element 32 (not visible in this Figure), thereby securing the heating element 32 and control arrangement to the main housing 5, by a plurality of fixing elements 28. In the embodiment depicted, the fixing elements 28 are in the form of screws. Of course, any other suitable fixing means may be employed.

Figure 3 shows a cutaway view of the flow heater 2, to reveal the internal space 30 within the heating chamber 4, along with the heating element 32 arranged therein.

In the embodiment depicted, at least a first portion 34 of the heating element 32 has a circular shape, i.e. a ring shape, and defines a circular void 36 which is devoid of any heating element. In the embodiment depicted, the heating element 32 is a spiral heating element, however it will be appreciated that any other form of heating element may be used. In some embodiments, as depicted, the main housing 5, of the heating chamber 4, comprises a protrusion 38 which extends into the circular void 36 of the heating element 32. In this embodiment, the protrusion 38 together with an outer wall of the main housing 5 defines a channel 40 which extends around the protrusion 38. As shown in Figure 3, the first portion 34 of the heating element 32 is arranged within the channel 40 and the channel 40 has a shape (defined by the outer wall of the heating chamber 4 and the protrusion 38) which generally matches that of the first portion 34 of the heating element 32.

As discussed previously, the channel 40 having a shape which corresponds to the first portion 34 of the heating element 32 may reduce the volume of the liquid which is heated within the heating chamber 4, which may improve the speed and efficiency at which liquid can be heated. The protrusion 38, which extends into the void 36, may also minimise the volume of liquid heated and also reduce the formation of cold-spots which may otherwise occur within the void 36.

The protrusion 38 extends from a base 46 of the main housing 5. It will be appreciated, however, that the protrusion 38 may extend from any other part of the flow heater 2, for example the protrusion may instead extend from the cover 6, or from a side wall within the heating chamber 4. In the embodiment depicted, the heating element 32 comprises a second portion 35 which is not arranged within the channel 40, and thereby does not act to heat the liquid during typical operation. In -17 -other embodiments, the heating element 32 may be arranged and/or may have a shape such that the entire heating element 32 is contained within the channel 40.

The protrusion 38 comprises a sloped portion 50 which extends from a peak 52 of the protrusion 38 towards a base of the protrusion 38, i.e. towards the base 46 of the main housing 4. The sloped portion 50 of the protrusion 38 will be discussed in more detail later below with reference to later Figures. The protrusion 38 may have any suitable form and need not necessarily comprise the sloped portion 50 as shown in the embodiments depicted.

In the cut-away view shown in Figure 3, the liquid outlet 48 of the heating chamber 4 is visible. As shown, the liquid outlet 48 may be arranged at a level within the liquid heating chamber 30 which is higher than the first portion 34 of the heating element 32. The liquid outlet 48 is raised from the base 46 of the main housing 4, such that the liquid only flows out through the liquid outlet 48 once there is a sufficient volume of liquid within the heating chamber 30. The liquid outlet 48 therefore effectively acts as a weir. The liquid outlet 48 is also arranged at a level above the first portion 34 of the heating element 32. As a result, during use, the entire of the first portion 34 will be immersed in liquid, and thus the entire first portion 34 will contribute towards the heating of the liquid within the channel 40.

An inlet temperature sensor 42, which may be in the form of a thermistor, and outlet temperature sensor 44, which may also be in the form of a thermistor, can also be seen in Figure 3. The inlet temperature sensor 42 is located at a position in the liquid heating chamber 30 below the liquid inlet 12. The outlet temperature sensor 44 is located proximal to the liquid outlet 48 so as to be sensitive to the temperature of the liquid leaving the liquid outlet 48.

The embodiment shown in Figure 3 also comprises a steam separation space 37, which is arranged above the channel 40. During use of the flow heater, any steam which forms from liquid being heated within the channel 40 may pass into the steam separation space 37. This steam may then pass out of the steam outlet 62, which is described in more detail further below with reference to Figure 8.

-18 -In the embodiment depicted, the minimum spacing between the heating element 32, specifically the first portion 34 thereof, and the protrusion 38 is 0.5 mm. Additionally, the protrusion 38 occupies around 45 To of the void 36. It will be appreciated, however, that the heating element 32 and protrusion 38 may have any other suitable spacing and the protrusion 38 may occupy any suitable portion of the void 36.

Figure 4 shows a top view of the flow heater 2 with the cover 6 removed showing the heating chamber 4 when viewed from above. As shown in this Figure, the channel 40 extends around the protrusion 38 so as to define a substantially circular channel 40 which matches the circular shape of the heating element 34. The channel 40 is delimited by the protrusion 38 and the side wall 7 of the main housing 5. The channel 40 may be considered to be ring-shaped or toroidal. Whilst in the embodiment depicted the first portion 34 of the heating element 32 is circular, and thus the channel 40 is circular, the channel 40 may have any suitable shape that matches the shape of the first portion 34 of the heating element 32 which is arranged therein.

A circle 41, indicating the point at which liquid enters the heating chamber 4, and arrows 43 indicating the flow of liquid through the channel 40, have been superimposed on to the view shown in Figure 4 to illustrate the flow of liquid through the heating chamber 4. In use, liquid enters the heating chamber 4 at the location indicated by circle 41. The liquid is then guided by the channel 40, which extends around either side of the protrusion 38, towards the liquid outlet 48. The liquid is heated by the portion of the heating element 34 which is within the channel 40, such that when it reaches the liquid outlet 48, it is heated to the desired temperature. The liquid will pass out through the liquid outlet 48 once the liquid volume within the channel 40 is sufficient to reach the level of the liquid outlet.

As is apparent in Figure 4, the channel 40 may be considered to be generally ring or toroidal shaped. Due to the arrangement of the liquid inlet 12 and the liquid outlet 48 which are at opposite ends of the heating chamber 4, in use, liquid flows through the channel 40 towards the liquid outlet 48 and despite the circular nature of the channel 40, the liquid does not flow back around the channel 40 towards the point indicated by circle 41, at which liquid first enters the channel 40. Instead, the -19 -liquid may form a small eddy behind the protrusion 38, just before the liquid outlet 48, and slow down. The liquid may then mix with the liquid from the other side of the channel 40, before escaping out of the liquid outlet 48. The channel 40 may be considered to comprise of two arc-shaped channels 40A, 40B which each extend around the protrusion 38 and together form circular channel 40.

Figure 5 shows a perspective view looking into the heating chamber 4 when viewed from above. As shown in this Figure, the heating element 32 may be attached to a mounting plate 54 which is mounted to a rear wall 56 of the main housing 5. The mounting plate 54 may extend through corresponding hole (not visible) in the rear wall 56 of the main housing 4, and be attached to the control arrangement 16 shown in Figure 2. This may secure the mounting plate 54, and thus the heating element 32, to the control arrangement 16 and secure the heating element 32 in position within the heating chamber 4.

Figure 6 shows a cross-sectional view through the flow heater 2. The rear wall 56 of the main housing 5 comprises an opening 58 through which internally threaded connection features 60 attached to the mounting plate 54 and/or the control 16 extend so as to facilitate mounting of the heating element 32 within the heating chamber 30. As shown, the mounting plate 54 comprises internally threaded connection features 60 which extend away from the mounting plate 54. Whilst only one internally threaded connection feature 60 is visible in this Figure, the mounting plate 54 may comprise two further connection features. The mounting plate 54 and control arrangement 16 are secured together, thereby securing the mounting plate 54 in position within the heating chamber 30, by fixing elements 28 which engage the internally threaded connection features. This acts to pull the mounting plate 54 against the rear wall 56 of the main housing 5 thereby securing the mounting plate 54, and thus the heating element 32, in position.

As can be seen most clearly in Figure 6, the sloped portion 50 of the protrusion 38 creates a space 51 adjacent the protrusion 38. The space 51 allows the heating element 32 to be inserted into the heating chamber 4 whilst keeping the volume of the heating chamber 4, specifically the channel 40, relatively small. Additionally, as depicted, the liquid inlet 12 may be aligned with the sloped portion 50 of the -20 -protrusion 38 such that in use liquid is appropriately directed by the sloped portion 50 into the channel 40.

Figures 7A-7B illustrate the insertion of the heating element 32, with the mounting plate 54 attached thereto, into the heating chamber 4. For clarity, only the base 46 of the heating chamber 30, including the protrusion 38, is shown. As depicted in Figure 7A, the heating element 32 and mounting plate 54 are inserted at an angle in the direction illustrated by arrow 61. The space 51, which is present due to the sloped portion 50, provides room within the internal space 30 within the heating chamber 4 to allow the heating element 32 and mounting portion 54 to be inserted into the heating chamber 4. The sloped portion 50 thus provides space to allow the assembly of the flow heater 2, whilst keeping the volume of the channel 40 as small as possible and as close in shape to the heating element 32, specifically the first portion 34 of the heating element 34 which sits in the channel 40.

As depicted in Figures 7B and 70, once the heating element 32 and mounting plate 54 have been inserted sufficiently far into the heating chamber 4, the heating element 32 and mounting plate 54 may then be levelled by moving the forward end 65 of the heating element 32 downwards in the direction shown by the arrow 63. At this point, the protrusion 38 may extend into the void 36 within the heating element 32. The mounting plate 54 may then be secured to the control arrangement 16 (shown in earlier Figures) in order to secure the mounting plate 54, and thus the heating element 32, in position.

Figure 8 shows a perspective view into the main housing 5 of the heating chamber 4, with the cover 6 removed. In the embodiment depicted, the flow heater 2 further comprises a steam outlet 62. The steam outlet 62 may be arranged within the heating chamber 4 at a level above the liquid outlet 48. During operation of the flow heater 2, steam may separate from the liquid within the heating chamber 4 and escape via the steam outlet 62. This may prevent the build-up of excessive pressure within the flow heater 2 which may otherwise cause damage to the flow heater 2.

Figure 9 shows a cross-sectional view through the flow heater 2 to show the internal structure of the dispense outlet 14. As shown, the dispense outlet 14 -21 -comprises a liquid conduit 64, which extends from the liquid outlet 48 and a steam conduit 66 which extends from the steam outlet 62. The liquid conduit 64 and steam conduit 66 are coaxial. As a result, during operation, liquid will be dispensed from the liquid conduit 64 and be surrounded by a curtain of steam from the steam conduit 66. This may advantageously indicate that the liquid being dispensed is hot, which may be desirous for a user.

Whilst in the embodiment described above the heating chamber 4 comprises a protrusion 38, it will be appreciated that such a protrusion may not be necessary in all embodiments. For example, a protrusion may not be needed when the heating element does not comprise a void or when the void is sufficiently small that it does not result in the formation of cold-spots and/or does not significantly increase the volume of liquid which is received within the channel.

Figure 10 shows a perspective view of a liquid heating appliance 168 which comprises the flow heater 2 shown in earlier Figures and described above. The liquid heating appliance 168 depicted may be a domestic countertop appliance. The liquid heating appliance 168 comprises a main body 170 which houses the flow heater 2 (not visible in this Figure). The appliance 168 also comprises a liquid reservoir 176 which supplies the flow heater 2 with liquid, e.g. water. A removable lid 174 is provided to allow access to the liquid reservoir, e.g. to permit refilling of the liquid reservoir 176. Instead of the liquid reservoir 176, the liquid heating appliance may be plumbed directly to a domestic water supply. A power plug 178 is provided for plugging the liquid heating appliance 168 into a power supply so as to supply the flow heater 2 with electrical power. Any suitable power plug 178 may be provided depending on the country in which the liquid heating appliance 168 is used.

The appliance 168 may also comprise a receptacle stand 180, on which a user may place a receptacle which they wish to fill with heated liquid. The liquid heating appliance 168 may further comprise a human-machine interface (HMI) 182 which allows a user to operate the liquid heating appliance 168. The HMI 182 may, for example, allow a user to adjust the temperature to which liquid is heated, control the rate at which liquid is dispensed and/or to control the volume of liquid which is dispensed.

-22 -Figure 11 shows a cut-away view through the liquid heating appliance 168 to reveal the internal components thereof. As depicted, the flow heater 2 is contained within the main body 170, specifically in an upper portion thereof The dispense outlet 14, of the flow heater 2, is arranged above the receptacle stand 180 such that in use liquid is dispensed in line with the receptacle stand 180, and thus into any receptacle arranged thereon. A pump 184 is provided to pump liquid from the reservoir 176 into the main housing 4 of the flow heater 2. Liquid is pumped from the liquid reservoir 176, via a liquid supply conduit 186 into the heating chamber 4.

The liquid is then heated in the heating chamber 4, before being dispensed out through the dispense outlet 14.

Figure 12 shows a perspective view of a flow heater 202 in accordance with another embodiment of the present invention. The flow heater 202 comprises a heating chamber 204 which is shown in transparent view to reveal the internal components of the flow heater 202. The heating chamber 204 is defined by a main housing 205 which has an open top which is sealed by a cover 206. The heating chamber 204 comprises a liquid inlet 212 and a dispense outlet 214. In the embodiment depicted in Figure 12, the flow heater 202 comprises a heating element 232 which comprises a first length 234A of heating element and a second length 234B of heating element. The first and second lengths 234A, 234B of the heating element are joined by a curved connecting portion 234C of heating element 232. As such, the first and second lengths 234A, 234B and curved connecting portion 234C of the heating element 232 have a U-shaped profile.

As shown, the heating chamber 204 comprises a channel 240, through which liquid passes, and which the first and second lengths 234A, 234B are present. The channel 240 has a shape which corresponds to the shape of the first and second lengths 234A, 234B and curved portion 234C of the heating element 232. The presence of multiple lengths of lengths of heating element 232 within a single channel 240, i.e. within the same channel 240, together with the shape of the channel 240 corresponding to the shape of the heating element, may advantageously allow the flow heater 202 to quickly and efficiently heat the liquid flowing therethrough.

-23 -Additionally, the corresponding shape of the channel 240 may help to reduce the number of cold spots in which the liquid is not heated. In the embodiment depicted, the channel 240 has a vertical orientation such that the liquid flows vertically within the flow heater 202. This is in contrast to the flow heater 2 described above, and shown in earlier Figures, in which the channel 40 is horizontal. Such a vertical arrangement may achieve maximum exposure of the heating element 232 to the liquid whilst keeping the footprint of the flow heater 202 to a minimum.

Similarly to the embodiment described above, a control arrangement 216 is connected to the heating element 232 and arranged to detect overheating within the heating chamber 204, for example overheating of the heating element 232 itself when there is insufficient liquid within the heating chamber 4.

The embodiment depicted in Figure 12 comprises an upper heating portion 231 which houses a further portion 235 of the heating element. In this embodiment, the liquid outlet 248 is located adjacent to the further portion 235 of the heating element 232 such that the entire heating element 232 is immersed in liquid during operation of the flow heater 202. This may improve the speed at which the flow heater 202 can heat liquid flowing therethrough.

The heating chamber 204 comprises a steam expansion space 237, similarly to the embodiment described above, which is arranged at a level above the liquid outlet 248.

Figure 13 shows a perspective view from above of the flow heater 202 with the cover 206 removed so as to show the internal components of the flow heater 202. Similarly to the embodiment described above, the flow heater 202 comprises a liquid outlet 248, and a steam outlet 262. Whilst not necessarily apparent in the view shown, the steam outlet 262 is arranged above the liquid outlet 248 such that the steam outlet 262 provides for the escape of steam from the heating chamber 204. The flow of liquid into the flow heater 202 may be controlled or set such that the liquid level within the heating chamber 204 does not rise above the level defined by the liquid outlet 248.

-24 -The flow heater 202 operates in a similar manner to the flow heater 2 described above, except that liquid flows vertically through the channel 240, as opposed to flowing horizontally, as is the case in the flow heater 2 described above.

The flow heaters 2, 202 and liquid heating appliance 168 described above may be used to heat any suitable liquid, for example water.

Claims

-25 -Claims: 1. A flow heater, for heating a liquid flowing therethrough, comprising: a heating chamber which comprises a liquid inlet through which the liquid enters the heating chamber and a liquid outlet through which heated liquid exits the heating chamber; a heating element arranged within heating chamber and positioned so as to contact and heat the liquid flowing through the heating chamber during use of the flow heater; wherein the heating chamber comprises a channel through which liquid flows in use, wherein a portion of the heating element is arranged within the channel, and wherein the channel has a shape which corresponds to the portion of the heating element which is arranged within the channel.
2. The flow heater of any preceding claim, wherein: the heating chamber comprises a protrusion extending into the heating chamber such that the channel extends around the protrusion; the heating element comprises a void; and the heating element is arranged within the heating chamber such that the protrusion extends into the void.
3. The flow heater of claim 2, wherein the protrusion extends from a main housing of the heating chamber.
4. The flow heater of claim 2 or 3, wherein the shape of the protrusion corresponds to the shape of the void of the heating element.
5. The flow heater of any of claims 2 to 4, wherein the protrusion occupies at least 20%, e.g. at least 25%, e.g. at least 30 %, e.g. at least 40 %, e.g. at least 45 %, e.g. at least 50 % of the void within the heating element.
6. The flow heater of any of claims 2 to 5, wherein the heating element comprises a void which has a closed curve shape and wherein the protrusion has a corresponding shape.
-26 - 7. The flow heater of any claims 2 to 6, wherein at least the portion of the heating element within the channel has a curved profile which defines a substantially circular-shaped void.
8. The flow heater of any preceding claim, wherein at least the portion of the heating element in the channel has a spiral profile.
9. The flow heater of any of claims 2-8, wherein a minimum spacing between the protrusion and the heating element is at least 0.2 mm, e.g. at least 0.3 mm, e.g. at least 0.4 mm, e.g. 0.5 mm.
10. The flow heater of any one of claims 2-9, wherein the heating chamber comprises a mounting portion for mounting the heating element within the heating chamber, and wherein the protrusion comprises a sloped portion which extends in a direction towards the mounting portion.
11. The flow heater of claim 10, wherein the liquid inlet is arranged above the sloped portion such that liquid falls onto the sloped portion.
12. The flow heater of any preceding claim, wherein the heating element comprises a first length of heating element and a second length of heating element, which is spaced from the first length of heating element, and wherein the first and second lengths of heating element extend together within the channel.
13. The flow heater of any preceding claim, wherein the liquid outlet within the heating chamber is arranged at a level within the heating chamber which is higher than the portion of the heating element which extends within the channel.
14. The flow heater of any preceding claim, wherein the flow heater further comprises an expansion space arranged above the channel.
15. The flow heater of any preceding claim, wherein the heating chamber further comprises a steam outlet, and wherein the steam outlet is arranged at a level which is higher than the liquid outlet.
-27 - 16. The flow heater of any preceding claim, wherein the flow heater further comprises an outlet temperature sensor positioned to measure the temperature of the liquid which flows out of the liquid outlet.
17. The flow heater of any preceding claim, wherein the flow heater further comprises an inlet temperature sensor positioned to measure the temperature of the liquid which flows into the heating chamber.
18. The flow heater of any preceding claim, wherein the flow heater further comprises a control arrangement mounted to the heating chamber and wherein the control arrangement is configured to cut a power supply to the heating element when a pre-set temperature is detected.
19. The flow heater of any preceding claim, wherein the heating element comprises a sheathed electrical heating element.
20. The flow heater of any preceding claim, further comprising a pump arranged to drive the liquid into the heating chamber.
21. The flow heater of any preceding claim, wherein the liquid comprises water.
22. The flow heater of any preceding claim, wherein the flow heater is configured to heat the liquid therein such that the liquid leaving the liquid outlet is at least 80 °C, e.g. at least 90 °C, e.g. at least 95 °C, e.g. 100 °C.
23. The flow heater of any preceding claim, wherein the heating element has power of at least 1 kW, e.g. at least 1.5 kW, e.g. at least 2 kW, e.g. 2.2 kW.
24. A liquid heating appliance, for providing heated liquid on demand, comprising a flow heater as claimed in any preceding claim.
25. The liquid heating appliance of claim 24, wherein the liquid heating appliance comprises a liquid reservoir fluidly connected to the flow heater.