Liquid heating appliances

Abstract

The liquid heating appliance (1) placed on an induction cooktop includes a liquid container (2), a ferromagnetic heating plate (6) attached to the liquid container (2) by a lifting mechanism (7), and a thermal actuator (10). The lifting mechanism (7) is operable to move the ferromagnetic heating plate (6) upward within the container (2) when the thermal actuator (10) detects that the heating plate (6) has exceeded a predetermined temperature.

Description

[Technical field]

[0001] The present invention relates to a liquid heating appliance, and more particularly to a liquid heating appliance for use with an induction cooker. [Background technology]

[0002] Liquid heating appliances such as kettles are commonly used in many homes. A conventional kettle includes a power source arranged to heat an element in the base of the kettle. It is known to provide dry-boil protection to a kettle using a thermal control including one or more thermal actuators mounted in good thermal contact with the heated base. The actuator operates to automatically shut off the power supply upon detecting an overheating condition, for example due to the appliance being emptied by boiling or being turned on with no water in it. Such a protection mechanism is therefore dependent on access to a power source.

[0003] Induction cookers have become increasingly popular in home kitchens for preparing food and beverages. An induction cooker comprises a coil that generates a magnetic field when an electric current is supplied to it. A ferromagnetic material placed within the magnetic field is heated by eddy currents induced in the material by the magnetic field. A typical induction heating vessel (such as a pot or kettle) contains a ferromagnetic component that is placed in contact with a liquid and that heats up when the vessel is placed on an energized induction cooker, thereby acting to heat the liquid within the vessel. Summary of the Invention [Problem to be solved by the invention]

[0004] Induction kettles have already been proposed where the control of the heating device is provided by the cooker rather than the kettle, the kettle being primarily passive like a saucepan. This separation of the control device and the kettle presents challenges with regard to automatic temperature control and switch-off, particularly with regard to boil-dry protection. Known boil-dry protection mechanisms such as those mentioned above are not suitable for induction kettles. As the kettle does not have its own power source, an actuator arranged to sense the temperature in the kettle would be located in an inappropriate position to cut off the power supply to the induction coil in the cooker. [Means for solving the problem]

[0005] The present invention aims to provide an improved device, and from a first aspect, the present invention provides a liquid heating device to be placed on an induction cooker, the liquid heating device comprising: A liquid container; a ferromagnetic heating plate mounted within the liquid container; a thermal actuator in thermal communication with the ferromagnetic heating plate and configured to detect when a temperature of the ferromagnetic heating plate exceeds a predetermined temperature; A lifting mechanism is provided to which the heating plate is attached and which is operable to move the heating plate upwardly within the liquid container when the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature.

[0006] It will be appreciated that the present invention provides an "dry burn switch off" feature, whereby upon detection of the ferromagnetic heating plate reaching a predetermined temperature (e.g. indicating a dry burn scenario), a lifting mechanism is configured to move the heating plate upwards away from the magnetic field of the induction cooker. Thus, even if the induction cooker continues to be energized, the heating plate will not be heated any further. This means that if the heating plate overheats, the induction heating is automatically interrupted, without requiring user intervention. In the context of overheating prevention, the thermal actuator may be configured to detect when the temperature of the ferromagnetic heating plate exceeds a predetermined temperature of at least 120°C, 125°C, 130°C, 135°C, or 140°C. As used herein, the expression "thermal communication" is intended to mean direct thermal communication (i.e. including thermal conduction).

[0007] By separating the dry-burn protection of the appliance from the induction cooker, the applicant is able to maintain the independent and passive nature of the appliance, thereby avoiding the need for complex connections, whether mechanical or electrical, between the kettle and the induction cooker. This means that the appliance according to the invention is suitable for use with domestic induction cookers without requiring any modification of the cooker.

[0008] The liquid container may be of any suitable or desired shape that defines a receiving volume for the liquid to be heated. Preferably, the liquid container can safely contain liquid, particularly water, that is heated to boiling. Preferably, the liquid container is made of a non-ferromagnetic material. In some embodiments, the liquid container may be made of a non-ferromagnetic metal, such as aluminum, copper, or brass. In some embodiments, the liquid container may be made of a non-metallic material, such as plastic, plastic composite (e.g., glass-reinforced plastic), glass, ceramic, and the like. Preferably, the liquid container is transparent or translucent. In a preferred set of embodiments, the liquid container is made of glass. This allows the contents of the liquid container to be visible to the user, and it can withstand very high temperatures. Inductive heating of a ferromagnetic heating plate without immersion in the liquid can reach up to 500°C.

[0009] Preferably, the liquid container has a base configured to contact the top surface of the induction cooker. Preferably, the base (e.g., its lower surface) is generally flat to enhance the stability of the appliance. The liquid container may be cylindrical. In some embodiments, the liquid container is frustoconical. The liquid container may include a base (e.g., located at the lower end of the container relative to the induction cooker on which the appliance is placed) and an upper opening (e.g., located at the upper end of the container). In some embodiments, the width (e.g., diameter) of the base is greater than the width (e.g., diameter) of the upper opening. This allows the appliance to have an aesthetic shape, for example, the liquid container looks like a traditional glass jug. However, as described below, such a shape may make it difficult to install a ferromagnetic heating plate.

[0010] The top opening of the container may be configured to receive a removable lid. The top opening may be circular (e.g., and the lid accordingly). The lid may define an opening for introducing liquid into the container. In some embodiments, the lid is configured to be removed to introduce liquid into the container. In some embodiments, the liquid container may include a spout. Liquid may be introduced into the container via the spout in addition to, or instead of, using a top opening that is closed by the lid.

[0011] The ferromagnetic heating plate may be made of one or more selected from iron, cobalt, nickel and ferromagnetic alloys thereof, for example steel. The ferromagnetic heating plate may be made of a composite material, for example ceramic with embedded ferromagnetic particles. Preferably, the parts of the device that are placed in the liquid container are manufactured from food-safe materials so that the liquid heated in the liquid container is safe to consume.

[0012] In at least some embodiments, the lifting mechanism is configured to attach to the ferromagnetic heating plate from its top side, meaning that the lifting mechanism is configured to pull the heating plate upwards within the liquid reservoir, rather than pushing the heating plate from below up.

[0013] In some embodiments, the lifting mechanism with the ferromagnetic heating plate attached is removable from the liquid container. The lifting mechanism (and in some embodiments a plunger, described below) may be attached to a removable lid of the device, allowing for easier access to the container and easier cleaning of the device.

[0014] The ferromagnetic heating plate may be of any suitable or desired shape. For example, the heating plate may be generally square, rectangular, or polygonal. In some embodiments, the heating plate is circular. In embodiments in which the container defines a top opening, the heating plate may be inserted into the container through the top opening. In such embodiments, the dimensions of the heating plate may be limited by the maximum dimension of the top opening. This means that the surface area of ​​the plate may be limited, which may limit the effective heating power of the heating plate. The appliance may be configured to provide a heating power of between 500W and 4000W, such as between 2000W and 3000W, for example about 2200W. It will be appreciated that this depends on the power of the cooker in which the appliance is placed.

[0015] Preferably, the heating plate is substantially planar (i.e. flat). The flat shape makes the plate easier and cheaper to manufacture. Furthermore, a flat plate helps ensure that the entire plate is located within the magnetic field of the induction cooker, thereby ensuring that the entire plate is heated by the magnetic field of the induction cooker.

[0016] In a set of preferred embodiments, the heater plate has a major axis and a minor axis. It will be understood that the terms "major axis" and "minor axis" are intended to refer to axes extending across the planar portion of the plate (i.e., in a plane perpendicular to the thickness of the heater plate), and that the dimension of the heater plate along the major axis is greater than the dimension of the heater plate along the minor axis. Thus, the heater plate may be non-circular.

[0017] The heater plate may have rotational symmetry of order two rather than rotational symmetry. The major and minor axes may be defined by a heater plate profile that is curvilinear (e.g., an elliptical profile) or that includes both curved and straight portions (e.g., an oval profile). In some embodiments, the heater plate is generally elliptical or oval. An elliptical heater plate may have a larger surface area for a given length of the major axis, but an oval heater plate may be easier to manufacture, handle, or install.

[0018] A non-circular (e.g. oval) heating plate is particularly advantageous in embodiments where the liquid container includes a top opening that is smaller than the base. The heating plate may be dimensioned such that the minor axis is equal to or smaller than the width of the top opening. However, if the heating plate is inserted into the container in a direction that is approximately collinear with the major axis of the heating plate, the major axis may be wider than the width of the top opening. The heating plate may be rotated as it approaches the (wider) base of the container. In this way, a larger surface area for the heating plate may be provided for a given top opening size. The larger the surface area of ​​the heating plate, the higher the effective heating power of the device.

[0019] This is believed to be novel and inventive in itself. Thus, viewed from a second aspect, the present invention provides a liquid heating apparatus comprising: A liquid container; a ferromagnetic heating plate having a major axis and a minor axis; A lifting mechanism is provided to which the heating plate is attached and which is operable to move the heating plate within the liquid container.

[0020] This aspect of the invention therefore provides a liquid heating appliance in which a heating plate (having a major and minor axis) is movable by a lifting mechanism, the appliance being preferably for use with an induction cooker.

[0021] As noted above, the ferromagnetic heating plate may be generally elliptical or oval in shape. In at least some embodiments according to this second aspect of the invention, the liquid container comprises a base disposed at a lower end of the container and an upper opening disposed at an upper end of the container, the width of the base being greater than the width of the upper opening.

[0022] In at least some embodiments according to this second aspect of the invention, the instrument further comprises a thermal actuator in thermal communication with the ferromagnetic heating plate and configured to detect when a temperature of the ferromagnetic heating plate exceeds a predetermined temperature, and the lifting mechanism is operable to move the heating plate upwardly within the liquid vessel when the thermal actuator detects that the temperature of the heating plate exceeds the predetermined temperature. Additionally, the heating plate may comprise a heat bridge configured to conduct heat from one or more portions of the heating plate to the thermal actuator, the heat bridge extending along a minor axis of the heating plate. This configuration takes advantage of the increased heating area provided along the minor axis by the non-circular shape of the heating plate, as described in more detail below.

[0023] Various features that may be applied alone or in combination to embodiments according to either the first or second aspect of the invention will now be described.

[0024] In some embodiments, the apparatus includes one or more separators disposed between the heating plate and the base of the liquid container. The separator(s) may be configured to act as a stop between the heating plate and the base of the liquid container. The separator(s) may be disposed on the liquid container (e.g., on the top surface of its base). In some embodiments, the separator is disposed on the heating plate (e.g., on its bottom surface). For example, as described below, the heating plate may include a number of legs disposed on its bottom surface (i.e., disposed to contact the base of the container and separate the base from the heating plate). In some embodiments, the separator(s) prevents at least a portion of the heating plate from resting directly on the top surface of the base of the liquid container. This creates a gap between the heating plate and the liquid container, which means that when liquid is dispensed into the liquid container, the liquid can flow under the heating plate. This increases the total surface area of ​​the heating plate that can come into contact with the liquid in the heating container, promoting convection in the container and helping to heat the liquid evenly.

[0025] The separator(s) may be arranged to provide a gap between the heating plate and the (base of) the liquid container of 0.5mm to 3mm, for example 0.7mm to 1.2mm, for example 1mm. The applicant has found that such a distance is beneficial as it means that the heating plate is close enough to the induction cooker so that the effectiveness of induction heating is not reduced, yet far enough from the base of the liquid container that the liquid can flow over the entire surface of the heating plate.

[0026] In some embodiments, the heating plate has a non-circular shape, so that the temperature of the plate during induction heating is not uniform. That is, some parts of the heating plate may be heated to a higher temperature. Even in the embodiment of the first aspect where the heating plate may be circular, if the appliance is not placed in the center of the induction cooker, the heat distribution of the heating plate will be non-uniform. This variation makes it difficult to optimally position the thermal actuator to ensure rapid detection of the maximum temperature across the heating plate. In some embodiments, the heating plate includes a heat bridge configured to conduct heat from one or more parts of the heating plate to the thermal actuator. This helps to reduce the risk that the thermal actuator fails to detect that the temperature of the heating plate exceeds a predetermined temperature.

[0027] In some embodiments, the heat bridge extends through the center of the heating plate (across the plane of the heating plate). In some embodiments, the heat bridge may extend along the long axis of the heating plate. Preferably, the heat bridge extends along the short axis of the heating plate. In some embodiments, the heat bridge extends along the (full) width of the heating plate along the short axis of the heating plate. The inventors have realized that when the heating plate comprises a long axis and a short axis, the hottest areas of the heating plate during induction heating by a circular coil are at the ends of the heating plate along the short axis. Thus, locating the heat bridge along the short axis in this way means that the heat bridge is in direct thermal communication with the hottest areas of the heating plate. This allows the heat of the heating plate in these areas to be conducted along the length of the heat bridge.

[0028] The heat bridge may be integrated with the heating plate. In some embodiments, the heat bridge is attached to the surface of the heating plate. In some preferred embodiments, the thermal actuator is attached to the heat bridge on the upper side of the heating plate. This means that the thermal actuator and the heat bridge do not interfere with the lower side of the heating plate, which has only a small separation distance from the base of the container, as described above. The heat bridge may be attached to the heating plate, for example, by brazing, soldering or riveting. The heat bridge is preferably welded (for example laser beam welding or spot welding) to the heating plate. The heat bridge preferably has a high thermal conductivity. For example, the heat bridge may be copper or aluminum.

[0029] During heating of the liquid in the appliance, a vapor layer may become trapped in the area between the base of the container and the heating plate. The vapor layer may act to insulate the heating plate from the liquid in the liquid container. This may cause the temperature in this area to rise quickly, while the temperature of the rest of the plate and the temperature of the liquid remain relatively low. As a result, a thermal actuator may detect a temperature higher than a predetermined temperature, and a lifting mechanism may move the heating plate in response. This means that the appliance may be switched off before the liquid in the appliance boils (so-called "dry boil interference").

[0030] Thus, in some embodiments, the heating plate defines one or more openings extending through the heating plate. The opening or openings may be equally spaced around the circumference of the heating plate. The opening or openings allow vapor generated under the heating plate to dissipate in the liquid container, reducing the risk of an insulating layer. The openings may also aid in the movement of the heating plate in the liquid container, if liquid is contained in the liquid container, because as the heating plate moves through the liquid, the liquid can flow through the opening(s) and not just around the periphery of the plate. As a result, a weaker lifting mechanism may be required. Furthermore, the position of the plate may be more easily reset by a user following the movement of the plate by the lifting mechanism.

[0031] In at least some embodiments, the one or more openings are disposed around the periphery of the thermal actuator, which helps ensure that heat is conducted to the thermal actuator rather than dissipated through the heating plate.

[0032] In some embodiments, the thermal actuator is attached (e.g., directly) to the heating plate. The thermal actuator may be attached (e.g., welded) to a top surface of the heating plate. The heating plate may comprise a casing attached to the heating plate to insulate the thermal actuator from the liquid in the liquid container. In embodiments in which the heating plate comprises a heat bridge, the thermal actuator may be attached to the heat bridge (e.g., on the upper side of the heating plate). Thus, in such embodiments, the thermal actuator is in thermal communication with the heating plate via the heat bridge of the heating plate.

[0033] In such an embodiment, a heat bridge can be used to conduct heat from more heated areas of the heating plate towards the thermal actuator, thereby increasing the range of locations where the thermal actuator can be placed and providing greater freedom in the design of the instrument.

[0034] Locating the thermal actuator on the heating plate (e.g. on a heat bridge in the heating plate) rather than elsewhere in the instrument means that the thermal actuator can more reliably detect when the temperature of the heating plate exceeds a predetermined temperature.

[0035] The thermal actuator may comprise an electronic temperature sensor (e.g., a thermistor) and may be configured to send an electrical signal to the lifting mechanism to operate the lifting mechanism.

[0036] In some preferred embodiments, the thermal actuator comprises a bimetallic actuator. The thermal actuator may be configured to deflect (e.g., with a snap action) when the thermal actuator detects that the temperature of the plate exceeds a predetermined temperature. The thermal actuator may be configured to deflect when the temperature of the thermal actuator exceeds a predetermined temperature.

[0037] The lifting mechanism is configured to move the heating plate upward, i.e., away from the base of the vessel. It will be appreciated that when the base of the appliance is placed on an energized induction cooker, moving the heating plate away from the base can move the heating plate away from the magnetic field generated by the induction cooker, preventing the heating plate from being coupled to the magnetic field of the induction cooker, thereby preventing further heating of the heating plate.

[0038] In some embodiments, the lifting mechanism is arranged to move the heating plate between a heating position and a non-heating position. In the heating position, the heating plate is located adjacent to (e.g., within 1.5 mm of) the top surface (inner surface) of the base of the liquid container. In this position, when the appliance is placed on the induction cooker and the cooker is energized, the heating plate is located in the magnetic field of the induction coil and therefore begins to heat. In the non-heating position, the heating plate is separated from the base of the container (e.g., by 20 mm or more). In this position, the heating plate is sufficiently separated from the induction cooker such that when the appliance is placed on the energized induction cooker, the heating plate is not heated by the magnetic field. Thus, in at least some embodiments, the lifting mechanism is operable to move the heating plate upward in the liquid container a distance of at least 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, or 20 mm. This may be the vertical distance between the heating position and the non-heating position of the heating plate.

[0039] The lifting mechanism may be configured to move only a portion of the heating plate upwards. The lifting mechanism may be configured to tilt the heating plate such that a portion of the heating plate moves upwards and away from the base of the appliance. In this way, the tilted portion of the heating plate can be moved away from the magnetic field generated by the induction cooker, so that a smaller area of ​​the heating plate is exposed to the magnetic field. This can reduce the effective heating power of the heating plate and limit further heating of the heating plate. However, the lifting mechanism is preferably configured to move the entire heating plate upwards. This means that the heating plate is moved straight up, rather than tilted. The heating plate may remain in a generally horizontal orientation while being lifted upwards. This is a faster and more reliable way to move the heating plate away from the magnetic field of the cooker.

[0040] The lifting mechanism may be located at the base of the container. In some embodiments, the lifting mechanism is attached to the lid of the instrument. The lifting mechanism may be configured to move the heating plate relative to the lid of the instrument.

[0041] The lifting mechanism may include a plunger that mounts the heating plate within the liquid container. The heating plate may be attached (e.g., welded) to the plunger at a lower end of the plunger such that the plunger extends perpendicularly from a surface of the heating plate. When the heating plate is disposed within the liquid container, the upper end of the plunger may extend through a top opening of the liquid container (i.e., the top opening of the liquid container may be disposed to receive a lid). The lid may define an opening through which the plunger is disposed to extend.

[0042] In some embodiments, the lifting mechanism comprises a lifting biasing member configured to act on the heating plate to move it. It will be appreciated that the lifting biasing member operates independently of the thermal actuator, i.e. the biasing force generated by the lifting biasing member to lift the plate is independent of any movement generated by the thermal actuator (e.g. due to a shape change upon reaching a predetermined temperature). The lifting biasing member may be configured to bias the heating plate (e.g. a part thereof) in a direction away from the base of the instrument. The lifting biasing member may be configured to act directly or indirectly on the heating plate. In embodiments where the lifting mechanism comprises a plunger, the lifting biasing member may be configured to act on the plunger to move the heating plate. Thus, in some embodiments, the lifting mechanism comprises a plunger to which the heating plate is attached and at least one lifting biasing member configured to act on the plunger to move the heating plate. The lifting biasing member may be configured to act on the plunger at an upper end of the plunger. Of course, the lift mechanism may include multiple lift biasing members, such as a pair of lift biasing members (such as springs) configured to act on either side of the plunger, which helps to ensure that the plunger moves upwards without tipping.

[0043] In some embodiments, the lifting mechanism comprises a latch movable between a latched configuration and an unlatched configuration. In the latched configuration, the latch may be configured to limit movement of the heating plate (e.g., by limiting upward movement of the plunger). When the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature, the lifting mechanism may be configured to move the latch to the unlatched configuration to allow movement of the heating plate (e.g., by allowing movement of the plunger). The latch may be configured to prevent movement of the heating plate (e.g., via the plunger) under the biasing force of the lifting biasing member(s) when the latch is in the latched configuration. In some embodiments, the latch may be located at an upper end of the plunger.

[0044] The lifting mechanism may include an unlatching portion configured to move the latch between the latched and unlatched configurations. In some embodiments, the unlatching portion may be located at a top end of the plunger. The unlatching portion may be pivotally mounted to the instrument such that pivotal movement of the unlatching portion moves the latch to the unlatched configuration.

[0045] The lift biasing member(s) may be configured to store potential energy. The lift biasing member(s) may be configured to release the stored potential energy when the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature. The lift biasing member(s) may comprise a helical (e.g., compression) spring.

[0046] The lifting biasing member(s) may be configured to act directly on the heating plate to move the plate. In some embodiments, the lifting biasing member(s) are configured to act on a plunger to move the plunger and thereby the heating plate. Preferably, the plunger is movable by a user to manually reset the position of the heating plate. The position of the heating plate may be manually reset by moving the plunger in a direction opposite to the direction in which the plunger is configured to be moved by the lifting mechanism. The plunger may comprise a button that can move the plunger to reset the heating plate. In embodiments in which the lifting mechanism comprises a latch, manual reset of the heating plate preferably moves the latch from an unlatched configuration to a latched configuration.

[0047] In some embodiments, the plunger comprises a piston head. The piston head may extend from an outer surface of the plunger. The plunger may comprise multiple (e.g., two) piston heads. The multiple piston heads may be equally spaced around the plunger. The lifting biasing member(s) may be configured to act on the piston head(s) (e.g., each piston head). Equally spaced around the plunger helps to balance the biasing force of the lifting biasing member(s) on the plunger, making it easier for the plunger (and thus the heating plate) to be lifted by the lifting mechanism. This also makes it easier to return the heating plate(s) to its initial position against the force of the lifting biasing member(s). In some embodiments, the lifting biasing member(s) is configured to act on a first surface of the piston head(s) to provide a lifting biasing force acting to move the plunger (and thus the heating plate).

[0048] In some embodiments, the instrument includes a damping mechanism configured to slow the movement of the heating plate as it is moved upward by the lifting mechanism. The damping mechanism may be configured to slow the movement of the heating plate as it approaches a "non-heating" position. This helps to extend the life of the instrument's components by reducing impact forces caused by the movement of the heating plate. It also helps to improve the aesthetics of the instrument.

[0049] The damping mechanism may comprise a damping spring configured to act on a second surface of the piston head(s) (e.g., the face of the piston head(s) opposite the first surface). The damping spring may be a separate component from the lift biasing spring(s). In some embodiments, the lift biasing spring(s) and damping spring are different parts of a single spring. A biasing / damping spring may be disposed (e.g., threaded) around the piston head(s) such that a lower portion of the spring extends from (and acts on) the first surface of the piston head(s) (i.e., acts as a lift biasing spring). An upper portion of the spring may extend from (and acts on) the second surface of the piston head(s) (i.e., acts as a damping spring).

[0050] In various embodiments, the instrument may comprise a manual intervention for interrupting the heating of the heating plate. The manual intervention may comprise its own lifting means for moving the heating plate. Preferably, the manual intervention is configured to operate the lifting mechanism (i.e. the same lifting mechanism operable to move the heating plate when the thermal actuator detects a predetermined temperature). This allows for a reduction in the complexity of the instrument. In some embodiments, the manual intervention may be configured to operate the lifting mechanism by moving the unlatching part (e.g., thereby moving the latch to the unlatching configuration). In some embodiments, the manual intervention comprises an extension member configured to act on the unlatching part of the lifting mechanism to move the latch to the unlatching configuration.

[0051] The manual intervention portion may be disposed on the plunger. In some embodiments, the manual intervention portion is disposed on a top end of the plunger. The manual intervention portion may comprise a push button comprising an extension member attached to the plunger for movement relative to the unlatching portion. The push button and extension member may be configured such that operation of the push button causes the extension member to act on the unlatching portion to move the latch to the unlatched configuration.

[0052] In various embodiments, the appliance may include a steam sensing device configured to detect boiling of the liquid in the liquid container. The appliance may include a steam chamber for receiving steam generated by boiling of the liquid in the liquid container. The steam chamber may be defined in a lid of the appliance. The steam sensing device may be disposed within the steam chamber. In some embodiments, the steam sensing device is disposed at a top end of the plunger.

[0053] The steam sensing device may comprise a steam sensing actuator (e.g., a bimetallic actuator). The steam sensing device may be configured to independently lift the heating plate upon detecting that the liquid in the container is boiling. In some preferred embodiments, the steam sensing device (e.g., its steam sensing actuator) is configured to operate a lifting mechanism (i.e., the same lifting mechanism operable to move the heating plate upon detecting that the liquid in the container is boiling) upon detecting that the liquid in the container is boiling. This may reduce the complexity of the appliance. The steam sensing device may be configured to operate the lifting mechanism by moving the unlatching portion (e.g., moving the latch to an unlatching configuration). It will thus be appreciated that the same lifting mechanism may be used to lift the heating plate upon detecting either that the liquid in the container is boiling or that the heating plate has reached a predetermined temperature (e.g., indicative of a dry-fire scenario). However, in some embodiments, separate lifting mechanisms may be provided.

[0054] The device may comprise one or more intermediate mechanisms for operating the lifting mechanism. In some embodiments, the thermal actuator is configured to operate the lifting mechanism by acting on the intermediate mechanism. The intermediate mechanism may be configured to operate the lifting mechanism by moving the unlatching part (e.g., thereby moving the latch to the unlatching configuration). This means that the thermal actuator does not have to be configured to act (e.g., directly) on the latch (to unlatch) upon detecting that the temperature of the heating plate exceeds a predetermined temperature. The thermal actuator can therefore be located at a location remote from the latch and unlatch parts of the lifting mechanism. In some embodiments, as already mentioned above, the latch and unlatch parts are located at the upper end of the plunger. The thermal actuator is located at the lower end of the plunger to which the heating plate is attached.

[0055] The intermediate mechanism may comprise a rod configured to be moved (e.g., lifted) by a thermal actuator. The rod may comprise a first end and a second end. The first end of the rod may be disposed adjacent to the thermal actuator and the second end of the rod may be disposed adjacent to the unlatching portion. The thermal actuator may be configured to act on the first end of the rod to cause the second end of the rod to act on the unlatching portion to move the latch to the unlatched configuration. The rod may be hollow. This reduces the weight of the rod, making it easier for the thermal actuator to move the rod. The intermediate mechanism may further comprise a lever. The rod may be configured to act on the unlatching portion via the lever. The intermediate mechanism may be configured to translate vertical movement of the rod (e.g., when acted on by the thermal actuator) into horizontal movement of the unlatching portion (e.g., to move the latch to the unlatching configuration).

[0056] The use of the intermediate mechanism allows the thermal actuator and the lifting mechanism to be located in different parts of the instrument, i.e., separate from each other within the liquid container. In embodiments where the thermal actuator is located on the heating plate, the intermediate mechanism acting between the thermal actuator and the lifting mechanism allows the lifting mechanism to be located elsewhere in the instrument. This can reduce the complexity of the instrument and limit the number of parts located in close proximity to the heating plate, where the temperature changes. The intermediate mechanism can be located on or within the plunger. In some embodiments, the intermediate mechanism is located inside the plunger. This can prevent the intermediate mechanism from being affected by the liquid in the container.

[0057] In embodiments in which the thermal actuator comprises a bimetallic actuator, a flexure of the bimetallic actuator may be configured to act on an intermediate mechanism (e.g., its rod) when the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature.

[0058] In various embodiments, the appliance includes a plate biasing member configured to bias the heating plate downward (e.g., toward the base of the container). The plate biasing member may apply a biasing force to the heating plate that pushes the heating plate into engagement with the base of the liquid container. This helps to ensure that the heating plate is as close as possible to the induction cooker during heating of the heating plate. In embodiments in which the appliance includes one or more separators configured to move the heating plate away from the base of the liquid container, the plate biasing member also helps to ensure that a correct separation is maintained. In some embodiments, the plate biasing member may be configured to act on the plunger, for example at the top end of the plunger, to bias the heating plate downward.

[0059] In some embodiments, the plate biasing member is configured with respect to the plunger to bias the heating plate toward the base of the vessel. In some embodiments, the plunger comprises an inner shaft movable within an outer sleeve, the outer sleeve surrounding the inner shaft. The inner shaft may be attached (e.g., welded) to the heating plate. The plate biasing member may be configured to act on the inner shaft to bias the heating plate downward. The lifting mechanism (e.g., its lifting biasing member(s)) may be configured to act on the outer sleeve to move the heating plate upward when the lifting mechanism is operated.

[0060] The lifting mechanism latch can ensure that the plunger is held in a predetermined vertical position relative to the base of the container when the heating plate is in its heating position. However, in embodiments in which a plate biasing member is provided to bias the heating plate toward the base of the container independent of the plunger, the plate biasing member helps to ensure that the heating plate is pressed close to the base of the liquid container without interfering with the lifting mechanism. The plate biasing member can apply a biasing force to the heating plate without resisting the biasing mechanism (e.g., its lifting biasing member(s)).

[0061] In some embodiments, a plate biasing member configured to bias the heating plate downwards towards the base of the container may function to bias a push button of the manual intervention unit upwards. The push button of the manual intervention unit may be configured to be depressed against the bias of the plate biasing member to initiate manual intervention. This serves to return the manual intervention unit to its original position.

[0062] Applicant has determined that the heating plate may come into contact with one or more side walls of the container. This may occur during operation of the lifting mechanism or while inserting or removing the heating plate from the container. There is also a risk of the heating plate moving sideways unintentionally, for example during transport. For example, a lifting mechanism, such as a plunger, that mounts the heating plate within the liquid container may act as a pendulum that brings the heating plate into contact with the side walls of the container.

[0063] It may be beneficial to avoid such contact between the heating plate and the sidewall of the vessel. Collisions between the heating plate and the vessel may damage the vessel, thereby forming failure points within the vessel. Furthermore, if the heating plate is heated to a significantly higher temperature (e.g., during a dry-fire scenario), physical contact between the heating plate and the vessel may cause thermal shock to the vessel. This may lead to failure of the vessel material, which is of course a safety hazard.

[0064] Thus, in some embodiments, the apparatus comprises a protective piece disposed between the ferromagnetic heating plate and a sidewall of the liquid container. The protective piece may be attached to the heating plate and / or the lifting mechanism. The protective piece is preferably configured to prevent the liquid container from contacting the heating plate. Such a protective piece is useful for all shapes of ferromagnetic heating plate.

[0065] This is believed to be novel and inventive in itself. Thus, viewed from a further aspect, the present invention provides a liquid heating device for placement on an induction cooker, the device comprising: A liquid container; a ferromagnetic heating plate mounted within the liquid container and spaced from a sidewall of the liquid container; and a protective component disposed between the ferromagnetic heating plate and the side wall of the liquid container.

[0066] In some embodiments, the instrument comprises a lifting mechanism to which the heating plate is attached. The lifting mechanism may be operable to move the heating plate upwardly within the liquid container.

[0067] The lifting mechanism may be manually operable. In some embodiments, the instrument comprises a thermal actuator in thermal communication with the ferromagnetic heating plate and configured to detect when a temperature of the ferromagnetic heating plate exceeds a predetermined temperature. The lifting mechanism may be operable to move the heating plate upwardly within the liquid vessel when the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature, as described above.

[0068] The sidewall is preferably a glass wall, hi some embodiments, the liquid container (e.g., the entirety of the liquid container) is a glass container.

[0069] The ferromagnetic heating plate may be any suitable shape, including circular or polygonal. In some embodiments, the ferromagnetic heating plate is non-circular. In some embodiments, the ferromagnetic heating plate has a major axis and a minor axis. In some embodiments, as described above, the heating plate is not rotationally symmetric. For example, the heating plate may be two-fold rotationally symmetric. The major and minor axes may be defined by a heating plate profile that is curvilinear (e.g., an elliptical profile) or that includes both curved and straight portions (e.g., an oval profile). In some embodiments, the heating plate is generally elliptical or oval. An elliptical heating plate may have a larger surface area for a given length of the major axis, but an oval heating plate may be easier to manufacture, handle, or install.

[0070] The protective part may extend around the periphery of the ferromagnetic heating plate. Preferably, the protective part is arranged in the same plane, radially outward of the outer edge of the heating plate (e.g. towards the side wall(s) of the liquid container). This means that the protective part is configured to contact the side wall of the container before the heating plate, and preferably the protective part is configured to prevent the ferromagnetic heating plate from directly contacting the side wall of the container. This reduces the possibility of the container being damaged by contact with the heating plate (which may become very hot during and after use).

[0071] In some embodiments, additionally or alternatively, the protective component comprises a heater plate cover attached to the ferromagnetic heater plate. The heater plate cover may be attached directly or indirectly to the heater plate (e.g., to a stem supporting the heater plate or to a lifting mechanism as described above). The heater plate cover may be attached to cover at least a portion of the top surface of the heater plate.

[0072] Providing a heater plate cover as part of the protective component means that the protective component can be more securely attached to the heater plate, as the likelihood of the protective component becoming dislodged due to relative movement between the heater plate and the side wall of the container can be reduced. The heater plate cover can also provide an aesthetic advantage, as it can hide the heater plate from the view of a user of the appliance. This can be desirable as the heater plate can discolour with use.

[0073] The heater plate cover may comprise any suitable or desired material. In some embodiments, the heater plate cover comprises a polymeric material. In some embodiments, the heater plate cover comprises stainless steel.

[0074] In some embodiments, the heater plate cover is attached to the heater plate such that it is spaced apart from the heater plate (e.g., its top surface), thereby limiting thermal conduction between the heater plate and the heater plate cover, which can be particularly advantageous when the heater plate cover is made of a material that has a lower melting point than the heater plate.

[0075] The heating plate cover may include a ferromagnetic material. It will therefore be appreciated that the heating plate cover may be heated when the appliance is placed on an energized induction cooker. This may be beneficial in some embodiments. However, preferably, the heating plate cover is spaced from the heating plate such that when the appliance is placed on an energized induction cooker, the heating plate does not experience induction heating as a result of the induction cooker, or experiences (e.g. substantially) less induction heating than the heating plate.

[0076] Preferably, the heater plate cover defines one or more openings for providing fluid communication between an upper side of the heater plate cover and an underside of the heater plate cover, thereby exposing the liquid in the liquid container to the upper surface of the heater plate. By spacing the heater plate cover away from the heater plate as described above, convection in the liquid container can be improved, thereby helping to uniformly heat the liquid in the container. Providing openings in the heater plate cover (and the heater plate as described above) can also promote convection in the liquid container.

[0077] The one or more openings may be of any suitable or desired shape. The opening(s) may be circular. Preferably, the openings are (e.g., angularly spaced) slots. In some embodiments, the total area of ​​the opening(s) defined in the heater plate cover is equal to or greater than the total area of ​​the opening(s) defined in the heater plate. This can reduce the likelihood that convection in the liquid container will be inhibited by the heater plate cover.

[0078] The heater plate cover may be of any suitable or desired shape. For example, the heater plate cover may be dome-shaped to accommodate a thermal actuator in thermal communication with the ferromagnetic heater plate (as described above). In some embodiments, the heater plate is generally flat. Preferably, the heater plate cover is shaped to generally conform to the contour of the upper surface of the heater plate.

[0079] Preferably, the protective part comprises an elastic material, for example silicone. In some embodiments, the protective part comprises a bumper ring. The bumper ring may be attached directly to the heating plate. However, preferably, the bumper ring is attached to a heating plate cover of the protective part. Attaching the bumper ring to the cover helps to protect the bumper ring from high temperatures induced in the heating plate.

[0080] In some embodiments, the bumper ring includes a C-shaped cross-section defining a horizontal upper lip and a horizontal lower lip, the upper lip and the lower lip being connected by a vertical rim. The upper lip may be disposed on an upper surface of the heater plate cover. The lower lip may be disposed on a lower surface of the heater plate cover. The lower lip may be disposed to space the heater plate cover away from the heater plate. Spaced away from the heater plate may be beneficial for reasons discussed above.

[0081] Preferably, the bumper ring (e.g. its vertical rim) extends around the periphery of the heater plate cover, between the heater plate cover and the side wall of the liquid container. Preferably, the outer edge of the bumper ring (e.g. its vertical rim) is located radially outward (towards the liquid container) of the outer edge of the heater plate. This means that the bumper ring will contact the wall of the container before the heater plate, meaning that there is less chance of the container being damaged.

[0082] The protective component may include an engagement mechanism for engaging with a corresponding engagement mechanism on the heating plate. The engagement mechanism may extend downwardly from the heating plate cover or bumper ring (e.g., an underside thereof). To secure the protective component to the heating plate, the protective component may include an engagement mechanism for engaging with a corresponding opening in the heating plate. Preferably, the protective component includes a plurality of engagement mechanisms spaced circumferentially around the protective component, each engaging with a corresponding plurality of engagement mechanisms in the heating plate.

[0083] In some embodiments, the engagement feature(s) extend from the bumper ring (e.g., from its upper or lower lip). The engagement feature(s) may comprise a rivet or tab configured to be received in a corresponding opening or slot. It will be appreciated that the engagement feature(s) and corresponding engagement feature(s) may be provided on the protective component and heating plate, respectively, or vice versa.

[0084] Applicants have determined that it is desirable to prevent thermal conduction from the heating plate to the base of the liquid container for reasons similar to those discussed above with respect to the sidewalls of the container. In embodiments of the invention in which the appliance includes one or more separators (e.g., legs) disposed between the heating plate and the base of the liquid container, the separators may provide a thermal conduction path between the heating plate and the base of the container.

[0085] Thus, in a set of embodiments, the one or more separators are positioned such that when the appliance is placed on an induction cooker and the induction cooker is energized to inductively heat the ferromagnetic heating plate, the one or more separators abut an area of ​​the ferromagnetic heating plate that heats less than the inductively heated area of ​​the ferromagnetic heating plate.

[0086] This feature is believed to be novel and inventive in itself. Thus, viewed from a further aspect, the present invention provides a liquid heating device for placement on an induction cooktop, the device comprising: a liquid container having a base; a ferromagnetic heating plate mounted within the liquid vessel, the heating plate having a major axis and a minor axis; one or more separators disposed between the heating plate and the base of the liquid container; The one or more separators are positioned such that, in use, when the appliance is placed on an energized induction cooker such that the ferromagnetic heating plate is centrally located above the induction cooker and an area of ​​the ferromagnetic heating plate is inductively heated, the one or more separators are located within or in contact with an area of ​​the ferromagnetic heating plate that is heated less than the inductively heated area of ​​the ferromagnetic heating plate.

[0087] This aspect is extended to a liquid heating device including an electromagnetic cooker and a liquid heating device disposed on the electromagnetic cooker, the liquid heating device comprising: a liquid container having a base; a ferromagnetic heating plate mounted within the liquid vessel, the heating plate having a major axis and a minor axis; one or more separators disposed between the heating plate and the base of the liquid container; The one or more separators are positioned such that when the appliance is placed on the induction cooker such that the ferromagnetic heating plate is centrally located above the induction cooker and the induction cooker is energized such that an area of ​​the ferromagnetic heating plate is inductively heated, the one or more separators are located within or in contact with an area of ​​the ferromagnetic heating plate that is heated less than the inductively heated area of ​​the ferromagnetic heating plate.

[0088] It will be appreciated that by providing one or more separators such that they are located within or in contact with less heated areas of the ferromagnetic heating plate compared to the (more) inductively heated areas of the heating plate, in use the liquid container may be protected from high levels of heat conduction from the heating plate through said separator(s). This increases safety as well as the life of the instrument. The potential for reduced heat conduction between the heating plate and the base of the container may also increase the efficiency of the instrument.

[0089] As described above, the separator(s) may be configured to act as a stop between the heating plate and the base of the liquid container. The separator(s) may be configured on the liquid container (e.g., on the top surface of its base) (i.e., such that the separator(s) are positioned in contact with the less heated areas of the heating plate). Preferably, the separator(s) may be configured on the heating plate (e.g., on its underside) (i.e., such that they are positioned in the less heated areas of the heating plate). For example, as described above, the heating plate may include a number of legs positioned on its underside (i.e., positioned in contact with the base of the container to separate the base from the heating plate).

[0090] The applicant has determined that an induction cooker typically includes a circular coil. This means that the heating area of ​​a heating plate placed in the center of the induction cooker is typically annular extending around the center of the heating plate. In some non-circular (e.g., elliptical) heating plates, the area of ​​the induction heating area of ​​the plate may extend (e.g., from the outer edge of the generally annular heating area) to the periphery of the plate. This means that it may be beneficial to position the separator(s) more centrally, away from the periphery of the plate. Thus, in some embodiments, the separator(s) is located within or in contact with the inner half of the heating plate.

[0091] The placement of the separator(s) within or in contact with the inner half of the heating plate is considered to be novel and inventive in itself. Viewed from a further aspect, therefore, the present invention provides a liquid heating appliance for placement on an induction cooktop, the appliance comprising: a liquid container having a base; a ferromagnetic heating plate mounted within the liquid container; one or more separators disposed between the heating plate and the base of the liquid container; The one or more separators are positioned within or adjacent to an inner half of a ferromagnetic heater plate.

[0092] Thus, for a ferromagnetic heater plate of width w and height h, the separator or separators would be positioned within or adjacent to a region of the heater plate having a width of w / 2 and a height of h / 2, and a center that is coaxial with the center of the heater plate. Applicant has determined that positioning the separator or separators in this manner reduces the likelihood that the legs will be exposed to the induction heating region of the heater plate during use. This is a counter-arrangement since for stability the separators (e.g., legs) will typically be positioned as wide as possible.

[0093] When the induction cooker is energized and the appliance is placed on the induction cooker, the temperature rise of the less heated area of ​​the heating plate is smaller than the heated area of ​​the heating plate. As mentioned above, the induction cooker includes a coil for generating a magnetic field. The heated area of ​​the heating plate is typically directly above the coil of the induction cooker. When the appliance is placed on the center of the induction cooker, the heated area of ​​the heating plate may include a substantially annular area that is coaxial with the center of the heating plate. Preferably, the one or more separators are arranged radially inside the annular area.

[0094] This means that the separator(s) are located in or adjacent to an area of ​​the heating plate that typically experiences less inductive heating during normal use of the appliance, which can result in reduced thermal transfer between the heating plate and the base of the liquid container, which helps protect the liquid container from damage due to overheating.

[0095] Preferably, the one or more separators are equiangularly spaced about the heating plate or base of the liquid heating vessel. In some embodiments, the liquid vessel may include a glass base. The liquid vessel may include one or more glass side walls.

[0096] In some embodiments, the separator(s) are spaced apart from the heating plate. The separator(s) may be attached to the lower surface of the heating plate and / or to the upper surface of the base of the liquid container. The separator(s) may be attached to the heating plate and / or the base of the container by any suitable or desired means. In some embodiments, the separator(s) are defined in the heating plate itself. The separator(s) may be defined in the base of the liquid container (e.g., its upper surface). The separator(s) may be made of any suitable or desired material. In some embodiments, the separator(s) comprise the same material as the heating plate. In some embodiments, the separator(s) comprise the same material as the liquid container (e.g., its base).

[0097] As will be appreciated by those skilled in the art, all aspects of the present invention may, and preferably do, include any one or more or all of the preferred and optional features of the embodiments discussed herein, as appropriate. [Brief description of the drawings]

[0098] Some preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 is a perspective view showing a liquid heating device according to one embodiment of the present invention.

[0099] FIG. 2a is a cross-sectional side view of the lid and lifting mechanism of the device shown in FIG.

[0100] 2b is a perspective view of a portion of the lifting device and steam sensing device of the appliance shown in FIG.

[0101] FIG. 3a is a side view of the plunger and heating plate of the device shown in FIG.

[0102] FIG. 3b is a front view of the plunger and heating plate of the device shown in FIG.

[0103] 3c is a first cross-sectional side view of the manual push button of the device shown in FIG.

[0104] FIG. 4 shows a schematic heat map of an oval heating plate when placed in the center of an induction cooker.

[0105] FIG. 5 shows a schematic heat map of the oval heating plate of FIG. 4 when placed in an off-center position on an induction cooktop.

[0106] FIG. 6 shows a schematic heat map of the heating plate of the appliance shown in FIG. 1 when the appliance is placed in the center of an induction cooker.

[0107] FIG. 7 shows a schematic heat map of the heating plate of the appliance shown in FIG. 1 when the appliance is placed in an off-center position on an induction cooker.

[0108] 8 is a cross-sectional perspective view of the dry-burn switch-off mechanism of the appliance shown in FIG. 1. FIG.

[0109] FIG. 9a is a cross-sectional side view of the device shown in FIG. 1 with the heating plate in a non-heating position.

[0110] FIG. 9b shows a cross-sectional side view of the device shown in FIG. 1 when the heating plate is moved downwards by the plunger.

[0111] FIG. 9c is a first cross-sectional side view of the device shown in FIG. 1 with the heating plate in the heating position.

[0112] FIG. 9d is a second cross-sectional side view of the device shown in FIG. 1 with the heating plate in the heating position.

[0113] FIG. 9e is a cross-sectional front view of the device shown in FIG. 1 with the heating plate in the heating position.

[0114] FIG. 10a is a first cross-sectional side view of the appliance shown in FIG. 1 after the heating plate has been raised by operation of the steam sensing device.

[0115] FIG. 10b is a second cross-sectional side view of the appliance shown in FIG. 1 after the heating plate has been raised by operation of the steam sensing device.

[0116] FIG. 10c is a cross-sectional front view of the appliance shown in FIG. 1 after the heating plate has been raised by operation of the steam sensing device.

[0117] FIG. 11 is a cross-sectional side view of the appliance shown in FIG. 1 after the dry-burn switch-off mechanism has been activated and before the heating plate has been raised.

[0118] 12 is a second cross-sectional side view of the manual push button of the device shown in FIG. 1. FIG.

[0119] FIG. 13 is a cross-sectional side view of the instrument shown in FIG. 1 after the manual intervention device has been operated and before the heating plate has been lifted.

[0120] FIG. 14a is a first cross-sectional side view of the device shown in FIG. 1 after a manual reset of the device has occurred.

[0121] FIG. 14b is a second cross-sectional side view of the device shown in FIG. 1 after a manual reset of the device has occurred.

[0122] FIG. 15 is a bottom view of a liquid heating device according to another embodiment of the present invention.

[0123] FIG. 16 shows a schematic heat map of the heating plate of the instrument shown in FIG.

[0124] FIG. 17 is a perspective view of the liquid heating device shown in FIG.

[0125] 18 is a perspective view of the underside of the heating plate cover of the instrument shown in FIG. 15. FIG.

[0126] FIG. 19 is a cross-sectional side view of the device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0127] FIG. 1 is a perspective view of a liquid heating appliance 1 (hereinafter appliance 1) according to one embodiment of the present invention. Appliance 1 comprises a transparent glass housing defining a liquid container 2 including a spout 4. Appliance 1 may be placed directly on an induction cooktop (not shown) during use. Container 2 comprises a handle 8 for lifting the appliance. Container 2 is generally frusto-conical in shape, having a circular base 3 and a circular top. The circumference of the circular top, from which spout 4 extends, is smaller than the circumference of base 3 and defines a circular opening for receiving a circular lid 5.

[0128] The instrument 1 further comprises a lifting mechanism 7 to which a ferromagnetic (e.g. steel) heating plate 6 is attached and which is operable to move the heating plate 6 within the liquid container 2. One of the main components of the lifting mechanism 7 is a plunger 58 which extends from above the lid 5 (when the lid 5 is placed on the container 2) through a central opening 5a defined in the lid 5 and into the liquid container 2. The heating plate 6 is welded to the lower end of the plunger 58. It can be seen that the heating plate 6 is non-circular and has a generally oval outer shape defining a major axis and a minor axis (described below with reference to Figures 6 and 7). The minor axis of the heating plate 6 is approximately equal to the diameter of the circular top opening that receives the lid 5, meaning that the heating plate 6 can be attached through the circular top opening when tilted.

[0129] If the heating plate 6 is instead circular, the diameter of the plate 6 (and therefore the surface area of ​​the plate 6) will be limited by the diameter of the circular top opening, since a larger plate 6 cannot be inserted through the opening into the liquid container 2. However, it will be appreciated that in the case of an oval heating plate 6, the plate 6 can be stretched further along its major axis (and thus provide a larger surface area) and still be insertable into the container 2 by aligning the minor axis of the heating plate 6 so that it is parallel to the plane of the circular opening and then rotating the plate 6 about its minor axis while lowering it into the liquid container 2. A larger surface area of ​​the heating plate 6 corresponds to a larger heating output, since a larger area of ​​the plate 6 is exposed to the magnetic field and heated by the induction cooker.

[0130] The lifting mechanism 7 is configured to move the heating plate 6 between a heating position (see Figure 1) and a non-heating position in which the heating plate 6 is lifted away from the base 3 of the container 2 (see Figures 10a-10c) and thus away from the magnetic field of the induction cooktop on which the appliance 1 is placed and therefore does not receive further heating by induction. The plunger 58 is mounted within the opening 5a such that the plunger 58 can move vertically to lift the heating plate 6 between the heating and non-heating positions.

[0131] The appliance 1 further comprises a dry switch-off (DSO) mechanism 10 located on the heating plate 6 at the base of the plunger 58 and interacting with the lifting mechanism 7. When the liquid container 2 is filled with liquid and the heating plate 6 is heated, the temperature of the DSO mechanism 10 and the liquid is limited to approximately the boiling temperature of the liquid (e.g. 100°C if the liquid is water). However, if there is no liquid in the liquid container 2, the temperature of the heating plate 6 can rise quickly to dangerous levels if the appliance 1 is not removed from the cooker. This is called "dry boil". The glass container 2 of the appliance 1 can typically withstand temperatures of 560°C to 600°C. Without the DSO mechanism 10, some areas of the heating plate 6 may exceed these temperatures in a dry boil situation.

[0132] As will be described in more detail below, the DSO mechanism 10 is configured to detect a "dry burn" scenario before any portion of the heating plate 6 reaches a dangerous temperature, and interrupt inductive heating of the appliance 1 accordingly.

[0133] Figure 2a shows a cross-sectional side view of the lid 5 of the device 1 shown in Figure 1. For ease of illustration, other parts of the device 1 have been removed.

[0134] The circular lid 5 is shaped to be received within the circular top opening of the glass container 2 of the instrument 1. The circumference of the lid 5 is therefore approximately equal to the circumference of the opening defined by the top of the container 2. The lid 5 includes a steam chest housing 56 that extends from the underside of the lid 5 into the liquid container 2 (when the lid 5 is placed on the container 2). The steam chest housing 56 contains various components of the lifting mechanism 7, as described below.

[0135] The steam chamber 22 is defined within a steam chamber housing 56. The steam chamber housing 56 further defines a steam inlet 24 that provides fluid communication between the liquid container 2 and the steam chamber 22. The steam chamber 22 is configured to receive steam generated upon boiling of the liquid in the liquid container 2 via the steam inlet 24. The steam exits the steam chamber 22 via a central opening 5a.

[0136] The vapor sensing device 25 is disposed within the vapor chamber 22 and includes a bimetallic vapor sensor 26, a latch release (an armature in this embodiment) 28, and a latch arm 30. The bimetallic vapor sensor 26 is disposed within the vapor chamber 22 adjacent the vapor inlet 24. The bimetallic vapor sensor 26 is configured to snap (i.e., flex) when a predetermined temperature is reached due to the presence of vapor within the vapor chamber 22 indicating that the liquid within the liquid container 2 has begun to boil. In this exemplary embodiment, the predetermined temperature of the bimetallic vapor sensor 26 is approximately 85° C. since the appliance 1 is used to boil water. The bimetallic vapor sensor 26 is configured such that flexing of the bimetallic vapor sensor 26 moves a free end (the upper end shown in FIG. 2a) of the bimetallic vapor sensor 26 toward the center of the vapor chamber 22.

[0137] An armature 28 of the vapor sensing device 25 is pivotally mounted within the vapor chamber 22. The armature 28 has an upper end 28a and a lower end 28b. The armature 28 is configured to pivot about a point between the upper end 28a and the lower end 28b. The upper end 28a of the armature 28 is adjacent to the bimetallic vapor sensor 26, and is configured such that when the bimetallic vapor sensor 26 flexes, the free end of the bimetallic vapor sensor 26 urges the upper end 28a of the armature 28 toward the center of the vapor chamber 22. This causes the armature 28 to pivot, thereby moving the lower end 28b of the armature away from the center of the vapor chamber 22.

[0138] The latch arm 30 of the vapor sensing device 25 is mounted at a pivot 30a on the steam chest housing 56. The latch arm 30 abuts the lower end 28b of the armature 28 and is configured to pivot the latch arm 30 away from the center of the steam chest 22 when the armature 28 pivots as a result of deflection of the bi-metal vapor sensor 26. A wire spring 29 (shown more clearly in FIG. 2b) is provided on the steam chest housing 56 to more securely engage the pivot arm 30 with the lower end 28b of the armature 28.

[0139] When the temperature of the bimetallic vapor sensor 26 drops and the bimetallic vapor sensor 26 returns to its "undeflected" position and the armature 28 returns to its original position (as described in more detail below), the biasing force of the wire spring 29 against the latch arm 30 allows the latch arm 30 to move with the armature 28 as the armature 28 returns to its initial position (i.e., the latch arm 30 and the lower end 28b of the armature 28 both move toward the center of the steam chamber 22).

[0140] 2a and 2b, the steam chamber housing 56 further defines a lower opening 56b configured to receive a plunger 58 (not shown in FIG. 2a). Thus, the plunger 58 extends from the top of the lid 5, into the central opening 5a, through the steam chamber 22, and out the lower opening 56b (and into the liquid container 2 when the lid 5 is placed on the container 2).

[0141] The steam chamber housing 56 further defines two main spring chambers 56a in which two lifting biasing members (main springs in this embodiment) 34 are respectively disposed. The second main spring 34 and the second main spring chamber 56a are spaced 180° from the first main spring 34 and the first main spring chamber 56a about the center of the steam chamber 22. Thus, only the first of the main spring 34 and main spring chambers 56a is shown in the cross-sectional view of FIG. 2a. Both main spring chambers are more clearly shown in FIG. 2b, and both main springs 34 are more clearly shown in FIG. 9e.

[0142] FIG. 2b is a perspective view of a portion of the lifting mechanism 7 and a portion of the steam sensing device 25. FIG. 2b more clearly shows the lower opening 56b defined in the base of the steam chamber housing 56, both main spring chambers 56a, and the wire spring 29. The wire spring 29 is mounted to the spring chamber housing 56 and is configured to provide a biasing force to the latch arm 30 to ensure close engagement between the latch arm 30 and the lower end 28b of the armature 28 as the armature pivots. In essence, the wire spring 29 ensures that the latch arm 30 always moves with (in contact with) the armature 28.

[0143] 3a is a side view of plunger 58 and ferromagnetic heating plate 6. Plunger 58 includes a steel casing 52 at the lower end of plunger 58. The upper surface of heating plate 6 is welded to the lower surface of casing 52. Casing 52 houses DSO mechanism 10.

[0144] In this embodiment, the plunger 58 further comprises a hollow shaft 50 extending vertically upward from the upper surface of the casing 52 along an axis perpendicular to the plane of the heating plate 6 and intersecting the center of the plate 6. However, it is contemplated that the plunger 58 could instead be mounted in an off-center arrangement to cantilever the heating plate 6. The upper end of the shaft 50 is fixedly attached to the support member 48. The plunger 58 further comprises a shaft sleeve 51 through which the shaft 50 extends. As will be explained in more detail below, the shaft 50 is movable relative to the shaft sleeve 51. The plunger 58 further comprises a manual push button 40 at its upper end, which is shown in more detail in FIG. 3c and described below. The shaft sleeve 51 defines an inclined surface 49 configured to abut the upper end 28a of the armature 28 when the plunger 58 is moved downwardly towards the base of the liquid container 2, as will be explained in more detail below.

[0145] The plunger 58 further comprises a first latch 32a and a first piston 36a, which extend radially from the outer surface of the shaft sleeve 51 in a first direction. The second latch 32a and the second piston 36a extend radially from the outer surface of the shaft sleeve 51 in a second direction diametrically opposite the first direction. In other words, the first latch 32a and the first piston 36a are 180° apart from the second latch 32b and the second piston 36b. Only the first latch 32a and the first piston 36a are shown in FIG. 3a. The latches 32a, 32b and the pistons 36a, 36b are more clearly shown in FIG. 3b.

[0146] The lifting mechanism 7 further comprises a DSO lever 38, the operation of which is explained in more detail below. The DSO lever 38 is pivotally mounted within the shaft 50 and projects partially through an opening in the shaft sleeve 51. In use (when the plunger 58 is positioned within the liquid container 2), the DSO lever 38 projects from the shaft sleeve 51 towards the vapour sensing device 25 shown in Figure 2. The interaction of the DSO lever 38 with the vapour sensing device 25 is explained in more detail below with reference to Figures 9c and 11.

[0147] FIG 3b is a front view of plunger 58. The first latch 32a and first piston 36a are shown in FIG 3b along with the second latch 32b and second piston 36b. The first piston 36a extends radially (in a first direction) from an outer surface of the first latch 32a. The second piston 36b extends radially (in a second direction) from an outer surface of the second latch 32b.

[0148] Although not shown in Figures 2a and 2b, the first and second pistons 36a, 36b extend into the first and second main spring chambers 56a, respectively. This is shown more clearly in Figure 9e. The first main spring 34 is threaded around the first piston 36a such that a portion of the spring 34 extends above the first piston 36a toward the lid 5 of the device 1, while the remaining portion of the first main spring 34 extends between the underside of the first piston 36a and the base of the first main spring chamber 56a.

[0149] FIG. 3c is a cross-sectional side view of the manual intervention portion (in this embodiment, a push button) 40 of the instrument 1 shown in FIG.

[0150] The manual push button 40 of the plunger 58 defines a central circular groove 40a in which a circular inner button 41 is movably mounted. The base of the circular groove 40a defines a central circular opening 40b and three minor openings 40c extending around the periphery of the circular opening 40b.

[0151] The inner button 41 comprises three hook portions 41a which extend vertically from the underside of the inner button 41 and pass vertically through three minor openings 40c respectively towards the shaft 50. The lower end of each hook portion 41a projects radially outwards and is configured to engage with the underside of the base of the circular groove 40a when the inner button 41 is in the raised position (as shown in Fig. 3c). This means that a downward movement of the manual push button 40 will cause the inner button 41 to move downwards accordingly. However, the inner button 41 can be depressed independently of the manual push button 40 during manual intervention, as will be explained below in relation to Fig. 13.

[0152] A support member 48 is fixedly attached to the upper end of the shaft 50. The support member 48 includes three radially projecting lobes 48a which extend to rest on an upper surface of the shaft sleeve 51. The plunger 58 further includes a plate biasing member (a compression spring in this embodiment) 46 which extends through a central circular opening 40b between the underside of the inner button 41 and the support member 48. The compression spring 46 thus acts to bias the shaft 50 downwards and bias the inner button 41 upwards (i.e. in the opposite direction).

[0153] It will be appreciated from this configuration that when a downward force is applied to the manual push button 40, there is produced a downward force on the inner button 41 (due to engagement between the hook portion 41a and the underside of the base of the circular groove 40a), as well as a downward force on the shaft 50 (due to the force transmitted to the support member 48 via the spring 46) and a downward force on the shaft sleeve 51 (due to the force transmitted to the shaft sleeve 51 by the lobe 48a of the support member 48).

[0154] Thus, when the manual push button 40 is depressed to return the heating plate 6 to the heating position, the shaft 50 and shaft sleeve 51 move downwards together, as will be explained below with reference to Figures 14a and 14b.

[0155] It will further be appreciated from the above configuration that, due to engagement between the upper surface of the shaft sleeve 51 and the lobe 48a of the support member 48, upward movement of the shaft sleeve 51 results in corresponding upward movement of the shaft 50, with the shaft 50 being lifted by the shaft sleeve 51 via the lobe 48a of the support member 48.

[0156] Returning to FIG. 1, during use, the appliance 1 is placed on an induction cooker (not shown). When the induction cooker is energized by passing a current through the coil of the induction cooker, a magnetic field is induced through the ferromagnetic heating plate 6, causing the temperature of the heating plate 6 to increase. The shape of the magnetic field induced by the circular induction coil in the induction cooker is approximately toroidal, with the center of the magnetic field located at the center of the induction coil. Thus, the outer parts of the heating plate 6 that are exposed to the magnetic field (when the appliance 1 is placed in the center of the induction cooker) experience greater heating than the areas not exposed to the central magnetic field.

[0157] 4 shows a schematic heat map of the non-circular heating plate 6 of the appliance 1 shown in FIG. 1 when it is separated from the appliance 1 and placed in the center of an induction cooker. The heating plate 6 has a major axis 60 and a minor axis 62. Typical dimensions of the heating plate 6 are a length along the major axis 60 of about 150 mm and a width along the minor axis 62 of about 136 mm. The center C of the induction cooker is shown in FIG. 4.

[0158] The first low-heating area 6a is located at the center of the heating plate 6 (the intersection of the major axis 60 and the minor axis 62). In this configuration, the center of the heating plate 6 coincides with the center C of the induction cooker. The first low-heating area 6a is also non-circular, having major and minor axes that are coaxial with the major and minor axes 60 and 62 of the heating plate 6, respectively.

[0159] The heating area 6b of the heating plate 6 is indicated by the shaded area in FIG. 4. The heating area 6b extends radially outward from the first low heating area 6a in a generally annular shape. The heating area 6b extends from the edge of the first low heating area 6a to the outer periphery of the heating plate 6 along the minor axis 62 of the heating plate 6a. However, the heating area 6b does not extend to the outer periphery of the heating plate 6 in a direction along the major axis 60 of the heating plate 6a. Thus, a second low heating area 6c and a third low heating area 6d are defined between the heating area 6b and the outer periphery of the heating plate 6 on either side of the heating area 6b along the major axis 60 (left and right sides of FIG. 4, respectively). The heating pattern is generally symmetrical with respect to the major axis 60 and the minor axis 62 of the heating plate 6.

[0160] It will thus be seen that the edges of the heater plate 6 along the minor axis 62 of the heater plate 6 experience greater heating than the edges of the heater plate 6 along the major axis 60 of the heater plate 6. This non-uniform heating pattern results from the non-circular shape of the heater plate 6.

[0161] FIG. 5 shows a schematic heat map of the non-circular heating plate 6 of FIG. 4 when placed at an off-center position on an induction cooker. The center C of the induction cooker is shown in FIG. 5. As can be seen, the first low heating area 6a is now offset from the center of the heating plate 6 along the minor axis 62 of the heating plate 6. Correspondingly, the annular heating area 6b is also offset from the center of the heating plate 6 along the minor axis 62 of the heating plate 6, so that the heating pattern is no longer symmetrical about the major axis 60 of the plate 6, but remains symmetrical about the minor axis 62. The second low heating area 6c extends over the remaining surface of the heating plate 6.

[0162] Depending on where the heating plate 6 is placed relative to the induction cooker, the heating area 6b may be located anywhere on the heating plate 6. Because it is desirable for the DSO mechanism 10 of the appliance 1 to sense the maximum temperature of the heating plate 6 so that it can switch off the appliance 1 before any part of the plate 6 reaches a dangerous temperature, the inventors have recognized that variations in the location of the heating area 6b may lead to difficulties in providing a reliable DSO mechanism 10. It is undesirable for the DSO mechanism 10 to have different response times depending on the placement of the appliance 1 on the induction cooker.

[0163] From the point of view of manufacturing and operating the appliance 1, it is advantageous to position the DSO mechanism 10 centrally on the heating plate 6. However, when the appliance 1 is placed in the center of the induction cooker, this positioning means that the DSO mechanism 10 is not exposed to the high temperatures of the heating area 6b of the heating plate 6, due to the shape of the heat distribution as shown in Figure 4. There is therefore a risk that the centrally positioned DSO mechanism 10 will not switch off the appliance 1, even if the temperature of the heating area 6b of the heating plate 6 is dangerously high.

[0164] Thus, as shown in Figures 6-8, the DSO mechanism 10 of the instrument 1 comprises a thermally conductive heat bridge 12 in good thermal communication with the upper surface of the heating plate 6 (e.g., welded to the heating plate 6). The heat bridge 12 is configured to conduct heat uniformly along its length. In this embodiment, the heat bridge 12 is shown as a generally rectangular strip, but it could have other shapes, for example a dog bone shape that overlaps more with the heating area 6b at the end of the heating plate 6.

[0165] 6 shows a schematic heat map of the non-circular heating plate 6 of FIG. 1 with heat bridge 12 when placed approximately centrally on an induction cooker. The centre C of the induction cooker is shown in FIG.

[0166] The heat bridge 12 extends along the minor axis 62 of the heating plate 6. Thus, when the appliance 1 is placed generally in the center of the induction cooker, the heat bridge 12 is configured to extend between the most heated areas of the plate (i.e., the furthest parts of the heating areas 6b along the minor axis 62), as described above with reference to FIG. 4. As a result, a high temperature gradient exists along the heat bridge 12 between the most heated areas of the plate 6 and the center of the plate 6, which means that heat is effectively transferred to the center of the plate 6. This arrangement of the heat bridge 12 takes advantage of the non-uniform heat distribution caused by the non-circular shape of the heating plate 6, by ensuring that the edges of the heat bridge 12 are located on the heating plate 6, resulting in maximum induction heating effect.

[0167] 1, when the DSO mechanism 10 is placed in the center of the heating plate 6, the heat bridge 12 serves to transfer heat to the DSO mechanism 10. This reduces the risk that the DSO mechanism 10 will fail to interrupt the inductive heating of the instrument 1 when the temperature of the heating area 6b of the heating plate 6 exceeds an acceptable threshold.

[0168] Heating of the liquid in the liquid container 2 of the instrument 1 may cause a vapor layer to become trapped in the area between the base 3 of the container 2 and the underside of the heating plate 6. The vapor layer may act to insulate the heating plate 6 from the liquid in the liquid container 2, causing the temperature of that underside to increase rapidly while the temperature of the remainder of the plate 6 and the temperature of the liquid remain relatively low. This may cause the DSO mechanism 10 to discontinue inductive heating of the instrument 1 before the liquid in the instrument 1 reaches its boiling point.

[0169] The heating plate 6 therefore defines an array of apertures (i.e. through holes) 64 which in this embodiment extend circumferentially around the centre of the heating plate 6. The apertures 64 are arranged around a centre point C where the thermal actuator is attached to the heat bridge 12. The holes 64 allow vapour generated below the heating plate 6 to escape upwards into the main volume of the liquid container 2 above the heating plate 6, thereby reducing the risk of an insulating layer growing.

[0170] FIG. 7 shows a schematic heat map of the non-circular heating plate 6 of FIG. 1 with the heat bridge 12 when placed in an off-center position on an induction cooktop. The center C of the induction cooktop is shown in FIG. 7. In this configuration, the heating area 6b of the heating plate 6 extends through the center of the heating plate 6 and therefore under the DSO mechanism 10 of the appliance 1. Thus, the DSO mechanism 10 can sense the maximum temperature of the heating plate 6 directly and not through the heat bridge 12. However, the temperature of the heating area 6b in the center of the plate 6 may be somewhat limited by the presence of holes 64, which reduces the amount of induction heating.

[0171] 6 and 7, it will be appreciated that the heat bridge 12 is most effective when the appliance 1 is placed in the center of the induction cooktop, because in this scenario the DSO mechanism 10 of the appliance 1 cannot directly sense the maximum temperature of the heating plate 6 and must rely on the heat bridge 12 to conduct heat from the edge of the heating plate 6 towards the center. This is also likely to be the most common placement of the appliance 1 with a typical user tending to place the appliance 1 in the center on the induction cooktop.

[0172] For a heating plate with a major axis length of about 150 mm, the width of the heat bridge 12 is 16 mm to 24 mm (e.g., about 18 mm), which is wide enough to allow the heat bridge 12 to collect a large amount of heat from the heating plate 6, but not so wide that the heat is dissipated before it reaches the central DSO mechanism 10.

[0173] FIG. 8 is a cross-sectional perspective view of the dry switch off (DSO) mechanism 10 of the appliance 1 shown in FIG.

[0174] As mentioned above, the DSO mechanism 10 comprises a copper heat bridge 12 extending along the minor axis of the heating plate 6. The DSO mechanism 10 further comprises a mounting plate 18 welded to the lower end of a hollow shaft 50 and to the upper surface of the heat bridge 12. An intermediate mechanism (a rigid rod in this embodiment) 16 is movably disposed within the hollow shaft 50 and extends through an opening in the mounting plate 18. A circular polymer or ceramic bead 20 is fixedly attached around the lower end of the rod 16 and engages the upper surface of the mounting plate 18 to act as a stop for the rod 16, thereby maintaining a predetermined distance between the lower end of the rod 16 and the upper surface of the heat bridge 12. The bead 20 also acts to center the rod 16 within the shaft 50.

[0175] The DSO mechanism 10 further comprises a thermal actuator in the form of a snap-action bimetallic actuator 14. The actuator 14 is attached to the heat bridge 12 and is located above the center of the heating plate 6. The actuator 14 is thus mounted in thermal communication with the ferromagnetic heating plate 6 and is configured to detect when the temperature of the ferromagnetic heating plate 6 exceeds a predetermined temperature. The rod bead 20 acts as a seal to prevent liquid from traveling up the shaft 50 and contacting the bimetallic actuator 14. The device 1 may also comprise a similar sealing component located at the upper end of the plunger 58 to prevent liquid from entering the shaft 50. The actuator 14 and heat bridge 12 are located on the upper surface of the heating plate 6 rather than the lower surface, which allows the heating plate 6 to be located as close as possible to the base 3 of the vessel and therefore to the induction cooktop during operation of the device 1. The actuator 14 snaps when a certain predetermined temperature (typically selected between 125°C and 140°C) is reached, thereby deflecting the free end of the bimetallic actuator 14 upwards and away from the heat bridge 12.

[0176] The free end of actuator 14 is disposed below the lower end of rod 16 such that when actuator 14 snaps and the free end of actuator 14 is moved upward, the free end of actuator 14 abuts against the lower end of rod 16 and pushes rod 16 upward. This movement therefore causes the free end of actuator 14 to lift rod 16 relative to shaft 50 and mounting plate 18. The free end of actuator 14 is configured to move approximately 2.1 mm in its snap action. Thus, rod 16 is moved upward accordingly (e.g., approximately 1.1 mm to 1.5 mm).

[0177] Figure 8 shows the position of the actuator 14 and rod 16 before the actuator 14 reaches a predetermined temperature. In this configuration, the free end of the actuator 14 is approximately 0.7mm to 1mm from the base of the rod 16. This distance is maintained by the rod bead 20 engaging the top surface of the mounting plate 18, allowing for a small amount of creep of the bimetallic actuator 14. This creep occurs as the temperature of the actuator 14 increases, but is small enough that the deflection of the actuator 14 upon snapping still acts to lift the rod 16.

[0178] The casing 52 is welded to the upper surface of the heating plate 6 and the outer surface of the shaft 50 so as to cover the heat bridge 12, the mounting plate 18, the bimetallic actuator 14, and the lower end of the shaft 50. The casing 52 insulates the DSO mechanism 10 from the liquid in the liquid container 2 to ensure operation of the bimetallic actuator 14.

[0179] Figure 9a shows a cross-sectional side view of the appliance 1 shown in Figure 1 with the heating plate 6 raised away from the base 3 of the appliance 1. As can be seen, the armature 28 is in a pivoted position (with the upper end 28a of the armature 28 moved towards the centre of the steam chamber 22).

[0180] FIG. 9b shows the appliance 1 after the plunger 58 has been pressed to move the heating plate 6 downwards towards the base 3 of the appliance 1. In this position, the inclined surface 49 at the upper end of the shaft sleeve 51 contacts and presses against the upper end 28a of the armature 28, thereby moving the upper end 28a away from the centre of the steam chamber 22 and onto the bimetal steam sensor 26. Thus, pressing down the plunger 58 can prepare the steam sensing device 25 for use with the appliance 1. This causes the lifting mechanism 7 to be in a latched configuration with the heating plate 6 lowered to the heating position. The user can fill the container 2 with water, place the appliance 1 on an energised induction cooker and start heating. Of course, the heating plate 6 may be pressed down to the heating position before or after placing the appliance 1 on the cooker.

[0181] As shown in FIG. 9a, the armature 28 is initially in a pivot configuration, which means that the latch arm 30 has been moved away from the center of the steam chamber 22. This means that as the plunger 58 is moved downwards, the first and second latches 32a, 32b can move past the latch arm 30 without engaging the latch arm 30. As the plunger 58 is moved further downwards, the inclined surface 49 of the shaft sleeve 51 contacts the upper end 28a of the armature 28. The inclined surface 49 of the shaft sleeve 51 pushes the upper end 28a of the armature 28 away from the center of the steam chamber 22 and rests on the bimetal steam sensor 26. This "resets" the position of the armature 28. As described above, the latch arm 30 is moved with the lower end 28b of the armature, and thus towards the center of the steam chamber 22.

[0182] As shown in Figure 9b, in the lowest position of the plunger 58, the legs 54 of the heating plate 6 engage the base 3 of the liquid container 2. When the user releases the downward force on the manual push button 40, the plunger 58 is moved upwards (to the position shown in Figures 9c-9e) by the biasing force of the main spring 34 until the first and second latches 32a, 32b engage the latch arms 30 (as shown in Figure 9d). The device 1 is now ready to heat.

[0183] Figures 9c and 9d show first and second cross-sectional side views of the instrument shown in Figure 1 with the lifting mechanism 7 in the latched configuration and the heating plate lowered to the heating position. The cross-section shown in Figure 9c is in a plane passing through the centre of the instrument 1. The cross-section shown in Figure 9d is in a plane slightly offset from the centre of the instrument 1.

[0184] In the heating position, the heating plate 6 is adjacent to the base 3 of the appliance 1. The heating plate 6 comprises separators (feet in this embodiment) 54 which project from the underside of the heating plate 6 towards the base 3 of the container 2, providing a uniform clearance of approximately 1 mm between the underside of the heating plate 6 and the upper surface of the base 3. While it is beneficial for reasons of induction efficiency to position the heating plate 6 as close as possible to the induction cooker during heating, this 1 mm clearance allows the liquid to flow around the heating plate 6. This increases the surface area of ​​the heating plate 6 in contact with the liquid, promoting convection within the liquid in the liquid container 2.

[0185] Figure 9c shows the armature 28 of the lifting mechanism 7 in an initial "latched" position before deflection of the bimetallic steam sensor 26. The DSO lever 38 has been pivoted downwardly out of contact with the lower end 28b of the armature 28. In Figure 9d, a second cross-sectional side view shows the interaction of the armature 28 with the latch arm 30, again located within the steam chamber 22. The steam chamber housing and many other components have been removed for clarity.

[0186] The first latch 32a, previously shown in Figures 3a and 3b, is shown in Figure 9d. The latch arm 30 is configured to engage both the first latch 32a and the second latch 32b (not shown in the cross-sectional view of Figure 9d) to prevent the plunger 58 from moving vertically upwardly away from the base 3. When the latch arm 30 pivots due to movement of the armature 28 as a result of deflection of the bi-metal vapor sensor 26, the latch arm 30 disengages from the first and second latches 32a, 32b (which allows the plunger 58 to move vertically away from the base 3 of the instrument 1, as will be further described below).

[0187] FIG. 9e shows a cross-sectional front view of the device 1 shown in FIG. 1 with the lifting mechanism 7 in the latched configuration and the heating plate 6 in the heating position.

[0188] In Fig. 9e, the lifting mechanism 7 is latched such that the plunger 58 is held with the heating plate 6 lowered such that the feet 54 of the heating plate 6 abut the base 3 of the liquid container 2. In this latched configuration, the lower portions of the respective main springs 34 are compressed by the first and second pistons 36a, 36b, thereby exerting a biasing force on the first and second pistons 36a, 36b which acts to urge the pistons 36a, 36b, and thus the plunger 58, upwardly and away from the base 3. However, as will be recalled from Fig. 9d, in the latched configuration shown, the plunger 58 is prevented from moving vertically upwardly by the engagement of the first and second latches 32a, 32b with the latch arms 30.

[0189] 9e also illustrates the configuration of the DSO mechanism 10 when the instrument 1 is operating normally with the heating plate 6 in the heating position. As can be seen, in this latched configuration, the bead 20 surrounding the lower end of the rod 16 abuts against the upper surface of the mounting plate 18, indicating that the DSO bi-metallic actuator 14 is not deflected.

[0190] The operation of the device 1 during boiling will now be described with reference to Figures 9c to 9e.

[0191] When an electric current is passed through the coil of the induction cooker, a magnetic field is generated which passes through the ferromagnetic heating plate 6. The heating plate 6 is heated by exposure to the magnetic field. As a result, the temperature of the liquid in the liquid container 2 in contact with the heating plate 6 begins to rise.

[0192] When the temperature of the liquid reaches its boiling point, the liquid evaporates into vapor and enters the vapor chamber 22 via vapor inlet 24. As the vapor enters the vapor chamber 22 and passes through the bimetallic vapor sensor 26 (see FIG. 9c), heat from the vapor is transferred to the bimetallic sensor, causing the temperature of the bimetallic sensor 26 to increase.

[0193] As described above, when the temperature of the bimetallic sensor 26 reaches a predetermined temperature (e.g., 85° C.), the bimetallic sensor 26 deflects, thereby pivoting the armature 28. As a result of this movement of the armature 28, the lower end 28b of the armature 28 is pivoted radially outwardly away from the shaft sleeve 51. This causes the latch arm 30 to pivot out of engagement with the first and second latches 32a, 32b.

[0194] As a result, the plunger 58, which has been biased upward by the compressed lower force of the main spring 34, is no longer prevented from moving upward. Thus, the main spring 34 pushes the first and second pistons 36a, 36b, which causes the plunger 58 and heating plate 6 to move upwardly, away from the base 3 of the vessel 2, to a non-heating position, as shown in Figures 10a-10c. Thus, the appliance 1 operates to automatically discontinue induction heating when boiling is sensed, without the need for manual intervention, such as operating the lifting mechanism 7 or lifting the entire appliance 1 off the cooker.

[0195] Figures 10a and 10b are first and second cross-sectional side views of the appliance shown in Figure 1 after the heating plate 6 has been lifted by operation of the steam sensing device 25 of the lifting mechanism 7, as described above. The cross-section shown in Figure 10a is in a plane passing through the centre of the appliance 1 (i.e. the same plane as Figure 9c). The cross-section shown in Figure 10b is in a plane slightly offset from the centre of the appliance 1 (i.e. the same plane as Figure 9d).

[0196] As shown in Figure 10a, the heating plate 6 has been lifted away from the base 3 of the container 2 to a non-heating position by the force of the main spring 34 acting on the first and second pistons 36a, 36b. This means that the heating plate 6 is no longer fully exposed to the magnetic field generated by the induction cooker and the heating plate 6 is no longer heated by induction. This prevents the appliance 1 (i.e. the heating plate 6) from continuing to heat (i.e. boil) the liquid in the liquid container 2 after the bimetallic vapor sensor 26 detects boiling.

[0197] The armature 28 of the lifting mechanism 7 is shown in a pivoted position with the upper end 28a of the armature 28 pivoted towards the shaft sleeve 51 and the lower end 28b of the armature 28 pivoted away from the shaft sleeve 51, thereby acting on the latch arm 30 (see FIG. 10b) to pivot out of engagement with the first and second latches 32a, 32b. This allows the shaft sleeve 51 in which the first and second latches 32a, 32b are located to move upwardly to the position shown in FIGS. 10a-10c. The pivoted position of the latch arm 30 is shown in FIG. 10b. To simplify the illustration, the steam chest housing and many other components have been removed.

[0198] FIG. 10c is a cross-sectional front view of the device 1, illustrating the extension of the lower portion of the main spring 34 after the first and second latches 32a, 32b are released from engagement with the latch arm 30. The upper portion of the main spring 34, which extends above the first and second pistons 36a, 36b, is shown in a compressed state. The upper portion of the main spring 34 is configured to abut against the top wall of the steam chest housing 56 when the first and second latches 32a, 32b are released and the first and second pistons 36a, 36b are allowed to rise with the plunger 58. This provides a damping mechanism (i.e., the upper portion of the main spring 34) that reduces the impact of the first and second pistons 36a, 36b against the top wall of the steam chest housing 56 when the first and second latches 32a, 32b are released, thereby mitigating the deceleration of the plunger 58 as it reaches its maximum height. This improves the user experience, safety and helps to extend the life of the device 1 components.

[0199] 10c also shows the configuration of the DSO mechanism 10 when the heating plate 6 is lifted by operation of the vapor sensing device 25 on the lifting mechanism 7. The DSO bimetallic actuator 14 is not deflected so that the bead 20 surrounding the lower end of the rod 16 continues to abut the upper surface of the mounting plate 18.

[0200] As an alternative scenario to that described in relation to Figures 9-10, the appliance 1 is placed on an energized induction cooker with no liquid present in the container 2. Figure 11 shows a side cross-sectional view of the appliance shown in Figure 1 when the heating plate 6 is lowered into the heating position and the DSO mechanism 10 is activated.

[0201] 11, the heating plate 6 has been returned to the heating position, with the legs 54 of the heating plate 6 abutting the base 3 of the liquid container 2. Thus, when the appliance 1 is placed on the induction cooktop and the induction coil is energized, the temperature of the heating plate 6 begins to increase, as described above. The heat bridge 12 is configured to conduct heat from the end of the heating plate 6 towards the DSO bimetallic actuator 14, causing the temperature of the actuator 14 to increase.

[0202] Before the temperature of the DSO bimetallic actuator 14 reaches a predetermined temperature, the DSO mechanism 10 is configured as shown in Figure 8. That is, the free end of the DSO bimetallic actuator 14 has not yet been deflected upwardly away from the base 3 of the instrument 1, so that the bead 20 surrounding the lower end of the rod 16 abuts against the upper surface of the mounting plate 18.

[0203] When the temperature of the DSO bimetallic actuator 14 reaches a predetermined temperature, the actuator 14 deflects such that the free end of the actuator 14 moves upward and away from the base 3 of the instrument 1. As a result, the free end of the actuator 14 abuts the lower end of the rod 16, lifting the rod 16 vertically upward within the shaft 50 and away from the base 3 of the vessel 2. This is shown in Figure 11. As can be seen, the rod 16 is lifted such that the bead 20 does not rest on the upper surface of the mounting plate 18. Instead, the lower end of the rod 16 rests on the free end of the DSO bimetallic actuator 14.

[0204] Figure 11 shows how the DSO lever 38 is acted upon by the rod 16 to pivot upwards from the position shown in Figure 9c. The DSO lever 38 is generally triangular in cross section with a first lobe extending in a first direction along an axis, a second lobe extending in an opposite direction along that axis, and a third lobe extending perpendicularly from the axis along which the first and second lobes are aligned. As shown in Figure 11, the first lobe 38a projects from the shaft 50 towards the lower end 28b of the armature 28 (through an opening in the shaft sleeve 51), the second lobe 38b extends within the shaft 50 to abut the upper end of the rod 16, and the third lobe 38c projects from the shaft 50 (through an opening in the shaft sleeve 51) towards the base 3 of the liquid container 2.

[0205] The DSO lever 38 is pivotally attached (directly or indirectly) to the shaft 50 of the plunger 58. When the rod 16 is lifted by flexure of the DSO bimetallic actuator 14, the upper end of the rod 16 pushes against the underside of the second lobe 38b of the DSO lever 38, causing the DSO lever 38 to rotate counterclockwise. As a result, the first lobe 38a of the DSO lever 38 pushes against the lower end 28b of the armature 28, thereby pivoting the armature 28 away from the sleeve 51 and moving the lifting mechanism 7 from the "latched" configuration to the "unlatched" configuration. The third lobe 38c of the DSO lever 38 acts as a stop to prevent the DSO lever 38 from rotating excessively by engaging the outer surface of the shaft sleeve 51.

[0206] FIG. 11 illustrates the "unlatched" configuration of the armature 28 and DSO lever 38 in the lifting mechanism 7. As described above, pivoting of the armature 28 causes the lower end 28b of the armature 28 to move the latch arm 30 out of engagement with the first and second latches 32a, 32b. As a result, the plunger 58 becomes free to lift under the force of the compressed main spring 34 in the same manner as described above with reference to FIGS. 9a-10c. This moves the heating plate 6 away from the magnetic field of the induction cooker to a non-heating position, thereby preventing further heating of the heating plate 6 and the liquid in the liquid container 2.

[0207] It will thus be appreciated that the DSO lever 38 converts movement of the rod 16 caused by operation of the DSO mechanism 10 into a pivoting movement of the armature 28 which unlatches the first and second latches 32a, 32b. This means that the same lifting mechanism 7 (i.e., the armature 28, latch arm 30, first and second latches 32a, 32b, and main spring 34) is used to lift the heating plate 6 whether the lifting is caused by the steam sensing device 25 or the DSO mechanism 10. The use of a single lifting mechanism 7 for both the steam switch off and dry-burn switch off significantly reduces the complexity of the appliance 1 and improves safety.

[0208] Figure 12 is a cross-sectional side view of the manual push button 40 of the appliance 1 shown in Figure 1. This view is similar to that shown in Figure 3c, but the cross section is taken along a different plane. In this cross-sectional view, it can be seen that the inner button 41 further comprises an extension arm 42 that extends perpendicularly from the underside of the inner button 41, parallel to the hook portion 41a. The extension arm 42 extends through an extension opening 40d defined in the base of the circular groove 40a and passes through the support member 48. When the lifting mechanism is in the "latched" configuration, the extension arm 42 extends into the steam chamber of the appliance.

[0209] FIG. 13 is a wide-area view of the cross-sectional side view shown in FIG. 12 after the manual intervention (i.e., the inner button 41) has been operated. During heating of the heating plate 6 by the induction cooker, the appliance 1 can be manually operated by the user to interrupt induction heating by depressing the inner button 41. When the inner button 41 is moved downwards against the bias of the compression spring 46, the extension arm 42 of the inner button 41 slides along a protrusion 44 provided on the outer surface of the shaft sleeve 51. At the base of the protrusion 44, the surface of the protrusion is inclined so that the protrusion 44 protrudes toward the lower end 28b of the armature 28. Thus, when the extension arm 42 reaches the base of the protrusion 44, the extension arm 42 bends radially outward and presses against the lower end 28b of the armature 28. As a result, the armature 28 pivots, thereby disengaging the latch arm 30 from the first and second latches 32a, 32b, and the unlatched lifting mechanism 7 becomes operable such that the plunger 58 and heating plate 6 are lifted by the main spring 34.

[0210] Thus, the extension arm 42 of the inner button 41 translates movement of the inner button 41 into pivotal movement of the armature 28. It will be appreciated that the same lifting mechanism 7 (i.e., armature 28, latch arm 30, first and second latches 32a, 32b, and main spring 34) that is used to lift the heating plate 6 when lifting is triggered by the steam sensing device 25 or DSO mechanism 10 also functions to lift the heating plate 6 when manual intervention is initiated by depressing the inner button 41.

[0211] The compression spring 46 ensures that the inner button 41 returns to the position shown in FIG. 12 when the user stops applying pressure to the inner button 41 .

[0212] After the heating plate 6 has been elevated to the non-heating position shown in Figures 10a-c, either as a result of detection of boiling by the steam sensing device 25, or as a result of detection of a "dry burn" scenario by the DSO mechanism 10, or as a result of manual intervention as described above, the appliance 1 must be reset in order to further heat the liquid in the liquid container 2. The lifting mechanism 7 is reset by lowering the plunger 58, and thus the heating plate 6, so that the heating plate 6 is again adjacent the base 3 of the container 2 in the heating position. This is shown in Figure 14a.

[0213] To lower the plunger 58, the user depresses the manual push button 40. As described above, this causes the plunger 58 and associated parts to move downward as a unit towards the base 3 against the opposing biasing force of the lower portion of the main spring 34, which is compressed by this movement (see FIG. 9e).

[0214] As shown in Figures 14a and 14b, the plunger 58 is moved downwards until the legs 54 of the heating plate 6 abut the base 3 of the container 2. When the legs 54 of the heating plate 6 contact the base 3, the shaft 50 is forced upwards against the bias of the compression spring 46. This ensures that the heating plate 6 is pressed into a heating position close to the base 3 of the container 2, thereby maintaining the desired 1 mm distance between them. The spring 46 is shown in Figure 14a to be over-compressed when the user is applying downward pressure on the manual push button 40. When this pressure is released, the spring 46 relaxes to its natural length (see FIG. 9c), the push button 40 is lifted away from the lid, and the biasing force of the spring 46 acts on the shaft 50 to keep the heating plate 6 lowered in its heating position regardless of small variations in the vertical distance between the latches 32a, 32b (see FIG. 14b) and the base 3 of the container 2 (e.g. as a result of variations in the thickness of the glass base 3).

[0215] As the plunger 58 is moved downward, the lower angled surfaces of the first and second latches 32a, 32b press against corresponding upper angled surfaces of the latch arms 30, thereby pivoting the latch arms 30 radially outward as the first and second latches 32a, 32b pass (see FIG. 14b). Once the first and second latches 32a, 32b have been moved under the latch arms 30, the latch arms 30 are caused to pivot radially inward by a wire biased spring (not shown) acting on the latch arms 30. The lifting mechanism 7 is thereby returned to the latched configuration.

[0216] 14b is a second cross-sectional side view of the device 1 after the plunger 58 has been manually depressed to manually reset the device 1. This cross-sectional view shows the relative positions of the latch arm 30 and first latch 32a with the heater plate 6 in its lowest position, with the foot 54 of the heater plate 6 abutting the base 3 of the container 2.

[0217] In FIG. 14b, it can be seen that there is a gap between the first and second latches 32a, 32b (but the second latch 32b is not shown in this view) and the surface of the latch arm 30 with which the first and second latches 32a, 32b engage. When the user stops depressing the manual push button 40, the upward biasing force of the lower part of the main spring (not shown) acts on the plunger 58 through the first and second pistons (not shown), lifting the plunger 58. This closes the gap between the first and second latches 32a, 32b and the latch arm 30, bringing these parts into a "latched" engagement and preventing the plunger 58 from moving further upward. Thus, the lifting mechanism 7 is returned to the "latched" configuration as shown in FIGS. 9c-9e.

[0218] In the above embodiment, it can be seen that the lifting mechanism 7 comprises a plunger 58 which mounts the heating plate 6 within the container 2. The lifting mechanism 7 is conveniently configured to move relative to the lid 5. To facilitate cleaning of the instrument 1 and its various parts, the lid 5 can be removed leaving the lifting mechanism 7 in place, or alternatively the entire lifting mechanism 7 can be removed from the liquid container 2 (e.g. together with the lid 5).

[0219] FIG. 15 is a bottom view of a liquid heating device 101 according to another embodiment of the present invention.

[0220] The instrument 101 is substantially similar to the instrument 1 shown in Figure 1, except for the differences described below. The instrument 101 comprises a transparent glass housing defining a liquid reservoir 102. The instrument 101 further comprises a ferromagnetic heating plate 106 mounted within the liquid reservoir 102 by a lifting mechanism (not shown) in a manner substantially similar to the heating plate 6 shown in Figure 1.

[0221] The heating plate 106 includes four legs 154 (embodied as separators) that project from an underside of the heating plate 106 toward the base of the vessel 102, thereby providing a uniform clearance of approximately 1 mm between the underside of the heating plate 106 and the top surface of the base. Openings 164 defined in the heating plate 106 allow for fluid communication between the underside of the heating plate 106 and the top side of the heating plate 106, thereby helping to improve convection within the instrument 101.

[0222] In contrast to the legs 54 of the heating plate 6 of the instrument shown in FIG. 1, which are located adjacent the periphery of the heating plate 6, the legs 154 of the heating plate 106 are located more centrally within the inner half of the area of ​​the heating plate 106.

[0223] Figure 16 shows a schematic heat map of the heating plate 106 of the appliance shown in Figure 15 when centered on an induction cooktop. The location of the heat bridge 112 is shown for reference.

[0224] The heating plate 106 has a major axis 160 and a minor axis 162. The center C of the induction cooker is shown in FIG.

[0225] A first low heating area 106a, a heating area 106b, and a second low heating area 106c are disposed on the heating plate 106 in a similar manner as described above with reference to FIGS.

[0226] As can be seen, the legs 154 of the heating plate 106 are located in a first low heating area 106a that is radially inward of the heating area 106b and the second low heating area 106c. This means that when the appliance 101 is placed in the center of an energized induction cooktop, the legs 154 are not exposed to the area 106b of the heating plate 106 that is heated to the highest temperature.

[0227] The legs 154 are positioned on the underside of the heating plate 106 such that they contact the base of the glass container 102 when the heating plate 106 is lowered to its heating position. Thus, the legs provide a thermal conduction path between the heating plate 106 and the glass container 102. By positioning the legs 154 in the first low heating area 106a of the heating plate 106, the thermal energy transferred from the heating plate 106 to the glass container 102 may be reduced, thereby reducing the risk of the glass container 102 being damaged by overheating or thermal shock.

[0228] Figure 17 is a perspective view of the liquid heating tool 101 shown in Figure 15. For clarity, the lifting mechanism and the top parts of the tool 101 have been removed.

[0229] The instrument 101 includes a stainless steel heater plate cover 109 attached to an upper surface of the heater plate 106. The heater plate cover 109 extends across the entire upper surface of the heater plate 106 and includes a number of openings 111 that allow fluid communication between the upper side of the heater plate 106 (and the underside of the heater plate 106 via openings 164 in the heater plate 106) and the liquid volume defined by the glass vessel 102 above the heater plate cover 109. This helps to improve convection within the instrument 101. The provision of the heater plate cover 109 also helps to hide the heater plate 106 from view of a user of the instrument 101, which may be aesthetically beneficial as the heater plate 106 may discolour during use.

[0230] The instrument 101 further comprises a silicone bumper ring 113 that extends around the periphery of the heater plate cover 109. The bumper ring 113 helps to protect the walls of the glass vessel 102 from being scratched by the heater plate 106 as it moves through the vessel 102. This reduces the risk of the walls of the glass vessel 102 developing defects that could become failure points for the glass at high temperatures, for example in a dry-fire scenario. The bumper ring 113 is attached to the heater plate cover 109 rather than the heater plate 106. This helps to protect the bumper ring 113 from thermal damage due to high temperatures within the heater plate 106.

[0231] 18 is a perspective view of the underside of the heater plate cover 109. For clarity, the heater plate has been removed from FIG.

[0232] As can be seen, the heater plate cover 109 includes four tangs 115 extending downwardly from the underside of the heater plate cover 109 towards the heater plate 106 about the center of the heater plate cover 109. The tangs 115 are configured to engage corresponding slots 119 in the heater plate 106 (see FIG. 15 ), thereby attaching the heater plate cover 109 to the heater plate 106. The tangs 115 also serve to maintain a spacing between the underside of the heater plate cover 109 and the upper surface of the heater plate 106, which helps to reduce the conductive flow of thermal energy from the heater plate 106 to the heater plate cover 109 when the instrument 101 is in use.

[0233] The heater plate cover 109 includes six outer spacing tabs 117 that extend downward from the lower periphery of the heater plate cover 109 toward the heater plate 106. The outer spacing tabs 117 help maintain the spacing between the heater plate cover 109 and the heater plate 106. This spacing is approximately 1 mm.

[0234] The bumper ring 113 further comprises six rivets 121 that extend through each of the openings 111 in the heater plate cover 109 from the top surface of the heater plate cover 109 to the underside of the heater plate cover 109. The rivets 121 serve to secure the bumper ring 113 to the heater plate cover 109.

[0235] Figure 19 is a cross-sectional side view of the fixture 101 shown in Figure 15. It can be seen that the rivets 121 of the bumper ring 113 extend from an upper lip 113a of the bumper ring 113 which is disposed to lie on the periphery of the top surface of the heater plate cover 109. The bumper ring 113 extends around and downwardly around the side of the heater plate cover 109 to form a lower lip 113b. It will thus be seen that the bumper ring 113 has a C-shaped cross-section.

[0236] Four of the outer spaced tabs 117 extend through respective openings in the lower lip 113b of the bumper ring 113, thereby helping to secure the bumper ring 113 to the heater plate cover 109. The outer spaced tabs 117 and the rivets 121 together help to prevent the bumper ring 113 from becoming dislodged from the heater plate cover 109 during movement of the heater plate cover 109 within the container 102.

[0237] 19, the bumper ring 113 extends radially outward beyond the heater plate 106, which means that in the event of relative lateral movement between the heater plate 106 and the wall of the container 102, the bumper ring 113 will contact the wall of the glass container 102 before the heater plate 106. This helps to protect the glass wall of the container 102 from damage.

Claims

1. A liquid heating device that is placed on an electromagnetic cooker, A liquid container; a ferromagnetic heating plate mounted within the liquid vessel; a thermal actuator in thermal communication with the ferromagnetic heating plate and configured to detect when a temperature of the ferromagnetic heating plate exceeds a predetermined temperature; a lifting mechanism to which the heating plate is attached and operable to move the heating plate upwardly within the liquid container when the thermal actuator detects that the temperature of the heating plate exceeds a predetermined temperature. A liquid heating device characterized by:

2. The lifting mechanism includes a plunger having the heating plate attached to a lower end thereof, and a lifting biasing member configured to act on the plunger at an upper end thereof to move the heating plate upward when the lifting mechanism is operated.

2. The liquid heating device according to claim 1 .

3. the lifting mechanism includes a latch and an unlatch portion disposed at an upper end of the plunger; the latch is moved by the unlatching portion to a latching configuration in which the latch is configured to restrict upward movement of the plunger and an unlatching configuration in which the latch is configured to allow movement of the plunger; The liquid heating device further includes an intermediate mechanism configured to operate the lifting mechanism by moving the unlatching portion under the action of the thermal actuator.

3. A liquid heating device according to claim 2.

4. The intermediate mechanism is disposed inside the plunger.

4. A liquid heating device according to claim 3.

5. and a steam sensing device configured to detect when liquid in the liquid container has boiled and to operate the lifting mechanism accordingly. A liquid heating appliance according to any one of the preceding claims.

6. The lifting mechanism includes: A plunger having the heating plate attached to its lower end; A latch and unlatch portion is disposed at an upper end of the plunger, The vapor sensing device is disposed at the upper end of the plunger and operates the lifting mechanism by moving the latch release portion.

6. A liquid heating device as claimed in claim 5.

7. and a manual intervention unit configured to operate the lifting mechanism of the device. A liquid heating appliance according to any one of the preceding claims.

8. The lifting mechanism includes: A plunger having the heating plate attached to its lower end; A latch and unlatch portion is disposed at an upper end of the plunger, The manual intervention portion is disposed at the upper end of the plunger and operates the lifting mechanism by moving the latch release portion.

8. A liquid heating device according to claim 7.

9. a plate biasing member configured to bias the heating plate downwardly A liquid heating appliance according to any one of the preceding claims.

10. The lifting mechanism includes a plunger having the heating plate attached to a lower end thereof, and the plate biasing member is configured to act on the plunger at an upper end thereof to bias the heating plate downward.

10. A liquid heating device according to claim 9.

11. The plunger comprises an inner shaft movable within an outer sleeve, the outer sleeve surrounding the inner shaft, the plate biasing member configured to act on the inner shaft to bias the heating plate downward, and the lifting mechanism comprises a lifting biasing member configured to act on the outer sleeve to move the heating plate upward when the lifting mechanism is operated.

11. A liquid heating device as claimed in claim 10.

12. a damping mechanism configured to slow the movement of the heating plate as the heating plate is moved upward by the lifting mechanism. A liquid heating appliance according to any one of the preceding claims.

13. The heating plate includes one or more apertures extending therethrough, the one or more apertures being disposed about the thermal actuator. A liquid heating appliance according to any one of the preceding claims.

14. The heating plate includes a heat bridge configured to conduct heat from one or more portions of the heating plate to the thermal actuator. A liquid heating appliance according to any one of the preceding claims.

15. The thermal actuator is attached to the heat bridge above the heating plate.

15. A liquid heating device as claimed in claim 14.

16. The heating plate has a major axis and a minor axis, and the heat bridge extends along the minor axis of the heating plate. A liquid heating device according to claim 14 or 15.

17. The lifting mechanism with the heating plate attached thereto is removable from the liquid container. A liquid heating appliance according to any one of the preceding claims.

18. The ferromagnetic heating plate has a major axis and a minor axis. A liquid heating appliance according to any one of the preceding claims.

19. The apparatus further comprises a protective component disposed between the ferromagnetic heating plate and a side wall of the liquid container. A liquid heating appliance according to any one of the preceding claims.

20. The protective piece extends around the periphery of the ferromagnetic heating plate.

20. A liquid heating device as claimed in claim 19.

21. The protective component is disposed in the same plane and radially outward of the outer edge of the ferromagnetic heating plate.

21. A liquid heating device as claimed in claim 19 or 20.

22. The protective component comprises a heater plate cover attached to the ferromagnetic heater plate. A liquid heating device according to any one of claims 19 to 21.

23. The heating plate cover is attached to the heating plate so as to be spaced from the ferromagnetic heating plate.

23. A liquid heating apparatus as claimed in claim 22.

24. The heater plate cover defines one or more openings for providing fluid communication between an upper side of the heater plate cover and an underside of the heater plate cover. A liquid heating device as claimed in claim 22 or 23.

25. The protective component comprises a bumper ring attached to the heater plate cover and extending around an outer periphery of the heater plate cover. A liquid heating device according to any one of claims 22 to 24.

26. The outer edge of the bumper ring is disposed radially outward of the outer edge of the ferromagnetic heating plate.

26. A liquid heating device as claimed in claim 25.

27. The apparatus includes one or more separators disposed between the ferromagnetic heating plate and the base of the liquid container. A liquid heating appliance according to any one of the preceding claims.

28. The one or more separators are positioned such that when the appliance is placed on an induction cooker and the induction cooker is energized to inductively heat the heating plate, the one or more separators contact an area of ​​the ferromagnetic heating plate that is heated less than an inductively heated area of ​​the heating plate.

28. A liquid heating apparatus as claimed in claim 27.

29. The one or more separators are located within an inner half of the ferromagnetic heating plate.

29. A liquid heating apparatus as claimed in claim 28.

30. A liquid heating device that is placed on an electromagnetic cooker, a liquid container having a base; a ferromagnetic heating plate mounted within the liquid vessel; one or more separators disposed between the heating plate and the base of the liquid container; The one or more separators are located within or adjacent to an inner half of the ferromagnetic heating plate. A liquid heating device characterized by:

31. The one or more separators are disposed on the ferromagnetic heating plate.

31. A liquid heating device as claimed in claim 30.

32. a lifting mechanism to which the ferromagnetic heating plate is attached and operable to move the ferromagnetic heating plate upwardly within the liquid vessel.

32. A liquid heating device as claimed in claim 30 or claim 31.

33. The liquid container includes a base disposed at a lower end of the container and an upper opening disposed at an upper end of the container, the width of the base being greater than the width of the upper opening. A liquid heating appliance according to any one of the preceding claims.

34. A liquid heating device comprising an electromagnetic cooker and a liquid heating appliance according to any one of the preceding claims.

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