Patent Description:
Steam irons are known that include a steam generator and an ironing plate coupled to the steam generator and which contacts the garments to be ironed. Steam generated in the steam generator is expelled onto the garments through holes in the ironing plate. Such irons contain control electronics to control the operation of the steam generator within an optimum temperature range. The ironing plate is passively heated by conduction of heat from the steam generator at the areas of contact between the steam generator and the ironing plate. The control electronics maintain the operation of the steam generator and the thermally coupled ironing plate, within an optimum temperature range.

Steam generators in such known steam irons include a high power heating element which can cause a relatively large temperature overshoot in the steam generator. In certain circumstances, where a temperature overshoot occurs and the iron is left unused for a period of time, the thermal energy in the steam generator can cause the ironing plate to heat up to a temperature towards or even over the upper limit of the optimum temperature range. Such overheating can also create hot spots in the ironing plate proximate the areas where the steam generator is coupled to the ironing plate.

<CIT> discloses an iron having a thermally insulating structure between a heating element and a sole plate, which allows steam to pass. <CIT> discloses an iron with an insert between a heating element and a sole plate.

It is an object of the invention to provide a steam iron which substantially alleviates or overcomes the problems mentioned above.

According to the present invention, there is provided a steam iron comprising a steam generator comprising a main body portion including an electrical heating element to heat the steam generator, an ironing plate coupled via a thermal coupling to the steam generator and configured to be passively heated by conduction of heat from the steam generator via the thermal coupling, wherein the thermal coupling between the steam generator and the ironing plate comprises an indirect thermal path formed by a flange of the steam generator, the flange being in contact with the ironing plate and being spaced from the main body portion of the steam generator, the flange also being configured to space the main body portion of the steam generator from the ironing plate to restrict the conduction of heat from the main body portion of the steam generator to the ironing plate.

This advantageously avoids excessive heating of the steam generator from causing corresponding heat spikes on the ironing plate. The configuration also means that heat from the main body of the steam generator has to be conducted through a convoluted path to reach the ironing plate.

The flange may comprises a first portion extending in a first direction from the main body portion of the steam generator, and a second portion extending from the first portion such that a gap is defined between the main body portion of the steam generator and the second portion of the flange.

This configuration flange aids the restriction of the thermal path, and also helps separate the main body of the steam generator from the flange/thermal path, and the ironing plate. The flange may be between <NUM> - <NUM> thick. This provides a preferred thermal restriction performance.

The width of the flange at the contact point between the flange and the ironing plate may be between <NUM> - <NUM> over at least <NUM>% of the contact area. The exact width of the flange may be different at different points around the steam generator, and the average width of the flange may be between <NUM> - <NUM>. In particular, the average width of the flange at the contact point at the ironing plate may be between <NUM> - <NUM>.

The steam generator may be exclusively coupled to the ironing plate by the flange and the remainder of the steam generator may be spaced from the ironing plate. Alternatively, the steam generator may be primarily coupled to the ironing plate by the flange and the remainder of the steam generator may be spaced from the ironing plate over at least <NUM>% of the adjacent surface of the steam generator. This advantageously ensures the primary heat transfer path between the steam generator and the ironing plate is via the flange and little can be transmitted to the ironing plate via any other path.

The ratio of the mass of the steam generator to the mass of the ironing plate may be between <NUM>:<NUM> and <NUM>:<NUM>. This is a preferred optimum ratio for thermal inertia between the steam generator and the ironing plate, to ensure quicker heating of the steam generator, and less temperature fluctuations of the ironing plate.

The ironing plate may comprise an area of increased thickness in the region where the flange contacts the ironing plate to enhance thermal distribution of conducted heat from the flange through the ironing plate. This advantageously avoids hot spots on the ironing plate adjacent contact points with the steam generator.

The steam iron may further comprise a controller to control operation of the steam iron, wherein the controller is configured to perform a first heating operation upon initial heating of the steam iron, and perform a second heating operation during subsequent operation of the steam iron, wherein the first heating operation comprises heating the steam generator to a higher temperature range than with the second heating operation. This enables the ironing plate to reach operational temperature quicker despite the restricted thermal path between the steam generator and the ironing plate.

The first heating operation may comprise heating the steam generator to remain above a first minimum predetermined temperature, and the second heating operation comprises heating the steam generator to remain above a second minimum predetermined temperature, wherein the first minimum temperature is higher than the second minimum temperature.

During the second heating operation the steam generator may be maintained at a temperature between <NUM> and <NUM> degrees Celsius. The temperature is preferably maintained at or around <NUM> degrees Celsius.

The controller may be configured to perform the first heating operation until the ironing plate reaches a predetermined minimum operating temperature. The minimum operating temperature may be <NUM> degrees Celsius. This minimum temperature helps avoid performance problems arising from condensation of steam generated.

The controller may be configured to control the temperature of the steam generator such that the temperature of the ironing plate is maintained between <NUM> degrees Celsius and <NUM> degrees Celsius.

The steam iron may further comprise at least one of a motion sensor and an orientation sensor connected to the controller, and the controller is configured to control the heating of the steam generator in dependence upon at least one parameter of ironing direction, speed and iron orientation as detected by the at least one sensor. This enables the steam iron to be controlled appropriately according to use of the iron, to avoid overheating when not used and/or under-heating during sustained use.

The controller may be configured to control operation of the steam generator such that if the temperature of the steam generator falls below a first predetermined value, then the controller sets a steam generator heater switch OFF value for an initial heating cycle of the steam iron to a second predetermined value, whereas during subsequent ironing operation the steam generator is operated at a third predetermined temperature value, the third predetermined temperature value being higher than the first predetermined temperature value and lower than the second predetermined temperature value. This advantageously enables the ironing plate to be brought rapidly back to an operational temperature in the event the steam generator falls below a minimum temperature threshold, for example if the iron is turned off and restarted shortly thereafter. The temperature of the steam generator may be measured as the temperature of the main body portion of the steam generator.

In various embodiments, the flange of the steam generator may be integral with both steam generator and ironing plate to form a single piece, e.g. in the case of one casting.

It may be envisioned that the flange is part of the ironing plate instead of the steam generator. In other words, the flange extends from the ironing plate. The thermal coupling between the steam generator and the ironing plate may include an indirect thermal path formed by the flange of the ironing plate, the flange being in contact with the steam generator and being spaced from the main body portion of the steam generator, the flange being configured to space the main body portion of the steam generator from the ironing plate to restrict the conduction of heat from the main body portion of the steam generator to the ironing plate.

Referring now to <FIG>, a steam iron <NUM> according to a first embodiment of the invention is shown and comprises a housing <NUM> including a handle <NUM> and a heated ironing plate <NUM> which, in use, contacts garments being ironed. The ironing plate <NUM> includes a plurality of steam holes <NUM> through which steam can be expelled onto a garment being ironed.

The steam iron <NUM> comprises a steam generator <NUM> within the housing <NUM> which has an internal electrical heating element <NUM> that heats the body of the steam generator <NUM>. The steam iron <NUM> also includes a water reservoir (not shown) with a water supply pipe (not shown) configured to provide water to the steam generator <NUM> to be converted to steam. The steam iron <NUM> is configured such that steam generated by the steam generator <NUM> can be expelled through the steam holes <NUM> in the ironing plate <NUM>.

The steam iron <NUM> includes a water transfer mechanism to supply water from the reservoir to the steam generator. In the exemplary embodiment the water transfer mechanism comprises an electrical pump (not shown) controlled by a user. However, this may alternatively comprise a manually operated mechanical pumping mechanism without an electrical pump.

A controller <NUM> is connected to the heating element <NUM> and to a number of sensors on the steam iron to enable it to control the operation of the steam iron. The steam iron includes a motion/orientation sensor <NUM>, which may comprise a ball sensor or accelerometer, connected to the controller <NUM>. This can be used to determine whether the steam iron <NUM> is in use or not, by detecting whether the steam iron <NUM> is moving or is stationary, and/or the tilt angle of the steam iron <NUM> to determine whether the steam iron <NUM> is in the upright rest position or horizontal operative position. Signals from these sensor(s) can then be used to control operation of the heating element <NUM> of the steam generator <NUM>. For example, the heating element <NUM> may be controlled to a set temperature of the steam generator if the steam iron <NUM> is in use or in the operative position, and the heating element <NUM> may be controlled to a different set temperature of the steam generator or switched off when, or a pre-determined time period after, it is detected that the steam iron <NUM> is not in use or is in the upright rest position.

The steam generator <NUM> also includes a thermistor <NUM> which is connected to the controller <NUM> and is configured to detect a temperature of the steam generator <NUM> and provide a signal dependent on the detected temperature to the controller <NUM>. Optionally, the ironing plate <NUM> may include an additional thermistor <NUM> connected to the controller <NUM> to detect the temperature of the ironing plate <NUM> and provide a signal dependent on the ironing plate temperature to the controller <NUM>.

The ironing plate <NUM> is passively heated by heat transfer from the steam generator <NUM>. The steam generator <NUM> comprises a main body portion 15a and a contact flange <NUM> which extends from a peripheral edge of the main body portion 15a. The heating elements <NUM> are provided within the main body portion 15a. The steam generator <NUM> is disposed on the ironing plate <NUM> and is in contact with the ironing plate <NUM> by means of the contact flange <NUM> around the perimeter of the main body 15a of the steam generator <NUM> and which sits in a recess <NUM> formed around the ironing plate <NUM>. A sealing means (not shown) may be provided in or around the recess <NUM> to prevent steam leakage. The main body of the steam generator <NUM> is spaced from the ironing plate <NUM> almost at all points except the contact flange <NUM>, and is thereby a substantially suspended thermal mass configuration. In particular, across the central portion of the main body portion 15a of the steam generator <NUM>, an air gap <NUM> is provided between the steam generator <NUM> and the ironing plate <NUM>. The heat from the main body portion 15a of the steam generator <NUM> is primarily transferred to the ironing plate <NUM> by conduction through the contact flange <NUM>, with only a small proportion transferring to the ironing plate <NUM> by radiation or conduction/convection across the air gap <NUM> in areas other than the contact flange <NUM>. That is, the primary thermal coupling between the steam generator <NUM> and the ironing plate <NUM> is the contact flange <NUM>. The steam holes <NUM> in the ironing plate <NUM> are in fluid communication with the air gap <NUM> and, in use, the steam generator <NUM> provides steam into the air gap <NUM> which is then expelled out of the steam iron <NUM> through the steam holes <NUM>.

It can be seen from the cross-sectional views of <FIG>, and in particular <FIG>, that the contact flange <NUM> around the edge of the steam generator <NUM> is narrow with a narrow contact foot <NUM> where it contacts the ironing plate <NUM>, as shown by dimension "d". The contact flange <NUM> also provides a relatively long and narrow heat path between the main body portion 15a of the steam generator <NUM> and the ironing plate <NUM>. This heat path comprises a first fin <NUM> extending horizontally from the main body portion 15a of the steam generator <NUM>, and a second fin <NUM> extending vertically from the first fin <NUM>, the contact foot <NUM> being disposed at the remote end of the second fin <NUM>. This configuration provides an air space <NUM> between the main thermal mass of the steam generator <NUM>, namely the main body portion 15a, and the contact foot <NUM>. The contact flange <NUM> includes a vertical portion, namely the second fin <NUM>, which is spaced from the horizontally adjacent portion of the main body portion 15a of the steam generator <NUM>. The first and second fins <NUM>, <NUM> thereby provide a restricted thermal path between the main thermal mass of the steam generator <NUM>, that is, the main body portion 15a comprising the heating elements <NUM> and majority of the material mass of the steam generator <NUM>, and the ironing plate <NUM>. This configuration is such that the thermal path between the main body portion 15a of the steam generator <NUM> and the ironing plate <NUM> via the contact flange <NUM> is indirect, that is, the thermal path is non-linear and requires the transferred heat to follow the angled path through the contact flange <NUM> in a "goose-neck" type of shape. A non-linear thermal path may refer to a thermal path including a first thermal path component joined to a second thermal path component at an angle less than <NUM> °. The first thermal path component and/or second thermal path component may for instance be linear, curved or angled. This restricted heat path configuration acts to prevent any large fluctuations in the temperature of the main body portion 15a steam generator <NUM> from causing large fluctuations in the ironing plate temperature, thereby acting as a thermal "damper" and allowing the ironing plate temperature to remain more consistent.

<FIG> also illustrate that the recess <NUM> of the ironing plate <NUM> upon which the contact flange <NUM> sits is wider than the contact flange <NUM>, shown by dimension "r" indicated in <FIG> being wider than dimensions "d". Also, the ironing plate <NUM> includes a large thermal distribution area <NUM> having a relatively large mass of material between the recess <NUM> and the base surface <NUM> of the ironing plate <NUM>. The ironing plate <NUM> is thicker in the region of the thermal distribution area <NUM> than over the rest of the width of the ironing plate <NUM>. As such, the point at which the steam generator <NUM> contacts the ironing plate <NUM> is spaced further from the ironing surface <NUM> of the ironing plate <NUM> than the majority of the remainder of the opposite side of the ironing plate <NUM> is spaced from the ironing surface <NUM>. The large thermal distribution area <NUM> acts to allow heat from the steam generator <NUM> via the contact flange <NUM> to dissipate evenly across the surface area of the ironing plate <NUM>, as shown by arrows "a" in <FIG>, and to avoid localised "hot spots" on the surface of the ironing plate <NUM> proximate the contact foot <NUM> of the contact flange <NUM> of the steam generator <NUM>. Also, the width "r" of the recess <NUM> on which the contact flange <NUM> sits being greater than the width "d" of the contact foot <NUM>/contact flange <NUM> means that heat transmitted from the steam generator is quickly and readily conducted away from the contact flange <NUM>/contact foot <NUM>, enhancing the uniform heat distribution across the ironing plate <NUM>.

For comparison, a configuration of a known steam iron <NUM> is shown in <FIG>, and comprises a steam generator <NUM> coupled to an ironing plate <NUM>. The base of the steam generator <NUM> includes a contact foot <NUM> that sits directly on the ironing plate <NUM>. It can be seen that the contact foot <NUM> is formed closely with the main thermal mass of the steam generator <NUM> such that there is a substantially unrestricted and direct thermal path between the main thermal mass of the steam generator <NUM> and the contact foot <NUM>. Furthermore, the contact foot <NUM> is relatively wide, as shown by width "D" in <FIG>. In addition, the point at which the contact foot <NUM> is in contact with the ironing plate <NUM> is of substantially the same thickness as the majority of the width of the ironing plate <NUM>. Therefore, there is no region of increased mass or thickness of material around the contact foot <NUM> to act as a thermal distribution area, as in the steam iron <NUM> of the present invention. As such, heat is readily transferred from the steam generator <NUM> to the ironing plate <NUM>, and localised hot spots <NUM> are created at surface <NUM> of the ironing plate <NUM> corresponding to the position of the contact feet <NUM> of the steam generator <NUM>. Also, the substantially unrestricted thermal path from the steam generator <NUM> to the ironing plate <NUM> means that large temperature fluctuations of the steam generator <NUM> quickly and significantly affect the ironing plate <NUM>, and cause corresponding large temperature fluctuations in the ironing plate <NUM>.

The above-described differences between the steam iron <NUM> of the invention and known steam iron <NUM> configuration of the effects of steam generator temperature fluctuations and localised hot spots, is also affected by the relative thermal masses of the steam generators <NUM>, <NUM> and ironing plates <NUM>, <NUM>. Here, the "thermal mass" means the mass of material from which the component is formed that is subject to temperature changes during operation of the steam iron. That is, known steam irons <NUM> comprise a steam generator <NUM> with a significantly larger thermal mass than that of the ironing plate <NUM>. Typically, the ratio of the steam generator thermal mass to the ironing plate thermal mass is around <NUM>:<NUM> to <NUM>:<NUM>. This means that temperature changes in the steam generator <NUM> quickly and significantly affect the temperature of the ironing plate <NUM>. In the steam iron <NUM> of the present invention however, the steam generator <NUM> and the ironing plate <NUM> are configured such that the ratio of the steam generator thermal mass to the ironing plate thermal mass is around <NUM>:<NUM> to <NUM>:<NUM>. This further aids the thermal "damping" between the temperature fluctuations of the steam generator <NUM> (the active thermal mass) affecting the temperature of the ironing plate <NUM> (the passive thermal mass), meaning the temperature of the ironing plate <NUM> remains more stable during use. Also, the lower thermal mass of the steam generator <NUM> means that less thermal energy is stored in the steam generator <NUM> and so when the steam iron <NUM> is left static, the ironing plate <NUM> is not heated up as much as in known steam irons <NUM>, avoiding excessive ironing plate temperatures towards or above the optimal temperature range.

An advantage of the configuration of steam iron <NUM> of the invention over known steam irons is that the improved heat distribution throughout the ironing plate <NUM> from heat received directly from the steam generator <NUM> avoids the need for an intermediate plate to be provided between the steam generator (i.e. the active source of the heat) and the ironing plate (i.e. the portion that comes into contact with the garments being ironed). In some known steam irons, an intermediate plate is required to help even out the heat distribution between the steam generator and the ironing plate to avoid hot spots. In such arrangements, the heat is initially spread out across the intermediate plate from the discrete contact points of the steam generator, and the more evenly distributed heat is then transferred to the ironing plate. Avoiding the need for an intermediate plate makes the construction of the steam iron of the invention simpler, making the construction process shorter and thereby reducing manufacturing and parts cost.

In the steam iron <NUM> of the invention, a user does not need to adjust the temperature of the iron to allow for different types of fabrics of garments being ironed. The steam generated and expelled by the iron performs the majority of the garment de-wrinkling function. As such, the ironing plate <NUM> can be maintained at a relatively constant temperature, such as below <NUM> degrees Celsius. The above-described features of the steam iron <NUM> of the invention thereby act to allow a relatively constant temperature ironing plate <NUM> regardless of the use of the steam iron <NUM>. It also allows a more robust temperature control system to be used instead of the complex control algorithms required in known steam irons for adjusting the temperature of the steam generator <NUM> and ironing plate <NUM> to maintain the ironing plate <NUM> within optimal temperature limits, for the reasons explained below.

In the exemplary steam iron <NUM> of the invention, the steam generator temperature may be set to around <NUM> degrees Celsius for optimum functioning. Also, although the ironing plate <NUM> may be maintained at an optimum temperature of between <NUM> - <NUM> degrees Celsius, the ironing plate <NUM> needs to heat up to above <NUM> degrees Celsius because below this temperature, condensation of the steam generated can be detrimental to the steam iron performance. Therefore, a control scheme of the steam iron only allows steam activation to be enabled above an ironing plate temperature of <NUM> degrees Celsius.

An "iron ready time" is the time taken for the ironing plate <NUM> and steam generator <NUM> to reach an operational temperature when the steam iron <NUM> is first turned on. Usually this is the time for the ironing plate <NUM> and steam generator <NUM> to reach an operational temperature starting from room temperature. However, due to the configuration of the steam iron <NUM> of the invention described above, the iron ready time would be longer than for known steam irons <NUM> if a conventional control scheme or algorithm was to be used. In a conventional steam iron, the steam generator <NUM> is generally controlled to heat up until it reaches a maximum temperature as detected by the thermistor, at which point power is then cut so that the steam generator <NUM> cools down until it reaches a minimum threshold temperature. Normally, when starting up from cold, as thermal delays are more pronounced especially when the heating power is high, the initial temperature overshoot is high which results in the steam generator being raised to a much higher temperature than that in normal operation. When reaching the minimum temperature threshold, power is turned on again to heat the steam generator <NUM> to a lower maximum temperature, at which point the power is cut again and the steam generator <NUM> is heated until it reaches a further reduced maximum threshold temperature. The power is cut again and the steam generator <NUM> cools until it reaches the minimum threshold temperature, at which point power is supplied again. This cycle is repeated with the steam generator <NUM> being turned on again each time the steam generator <NUM> reaches the same minimum threshold temperature and the reducing maximum threshold temperatures aims to settle the steam generator <NUM> around an optimum operating temperature.

<FIG> shows a graph of various temperature readings during an initial heat-up process, taken at points on a steam iron <NUM> configured according to that of the present invention, but being operated using a conventional control algorithm from a known steam iron <NUM>. Line (i) represents the thermistor <NUM> reading representing the temperature of the steam generator <NUM>. Line (ii) is the temperature at the thermal fuse. Lines (iii) to (xii) represent temperature readings at various points across the surface of the ironing plate <NUM> as the ironing plate <NUM> is passively heated by the steam generator <NUM>. Such ironing plate temperature readings may optionally be detected by a thermistor <NUM> in or on the ironing plate. When the steam iron <NUM> is turned on, the steam generator <NUM> heats up from around <NUM> degrees Celsius to a first maximum temperature threshold, shown as around <NUM> degrees Celsius. The power is then cut and the steam generator <NUM> cools until it reaches its minimum temperature threshold, which it can be seen from <FIG> is around <NUM> degrees Celsius. The steam generator <NUM> is then powered again and heats up to a lower maximum threshold temperature of around <NUM> degrees Celsius before cooling to the lower threshold temperature. During this cycle, the temperature of the ironing plate <NUM> steadily increases until it reaches its minimum operating temperature of <NUM> degrees Celsius. In the process shown in <FIG>, this takes nearly <NUM> seconds, an iron ready time of well over <NUM> minutes, as indicated by the vertical dashed line intersecting the x-axis at the point all ironing plate temperate plot lines pass above the <NUM> degrees Celsius line of the graph.

In order to make a significantly quicker iron ready time than that when using a conventional control algorithm, embodiments may include a control scheme or algorithm for operating the steam iron <NUM> of the present invention. <FIG> shows a graph similar to that of <FIG>, showing various temperature readings during an initial heat-up process, taken at points on a steam iron <NUM> configured according to that of the present invention. However, the graph of <FIG> shows the steam iron <NUM> being operated using a control algorithm of the present invention. Line (i) represents the thermistor <NUM> reading representing the temperature of the steam generator <NUM>. Line (ii) is the temperature at the thermal fuse. Lines (iii) to (xv) represent temperature readings at various points across the surface of the ironing plate <NUM> as the ironing plate <NUM> is passively heated by the steam generator <NUM>.

The control algorithm according to various embodiments may comprise heating the steam generator <NUM> to a higher temperature for the first one or more cycles upon initial power on of the steam iron <NUM> before the steam generator <NUM> is controlled to remain around a reduced temperature level. This is achieved by having a higher minimum temperature threshold during the initial heating cycles of the steam generator <NUM> than during the later operational cycles of the control algorithm. Referring to <FIG>, the steam generator <NUM> is initially heated to a maximum temperature threshold of around <NUM> degrees Celsius at which point the heating is stopped and the steam generator <NUM> begins to cool. However, the initial minimum temperature threshold is set relatively high, at around <NUM> degrees Celsius, at which point the steam generator <NUM> is powered again. In the exemplary control algorithm represented by the graph of <FIG>, the maximum temperature threshold remains the same for the second cycle and so the steam generator heats again to around <NUM> degrees Celsius before the power to the steam generator <NUM> is stopped again. By the time the steam generator <NUM> cools to the initial minimum temperature threshold, the ironing plate <NUM> has already reached the minimum operating temperature of <NUM> degrees Celsius. In the process shown in <FIG>, as indicated by the vertical dashed line intersecting the x-axis at the point all ironing plate temperate plot lines pass above the <NUM> degrees Celsius line of the graph, this takes about <NUM> seconds, around <NUM> seconds quicker than if a conventional control algorithm was used. Therefore, maintaining the steam generator <NUM> at the elevated temperature for the initial one or more heating cycles during start up ensures quicker heat transfer to the ironing plate <NUM> and so a quicker iron ready time. Once the ironing plate has <NUM> reached the minimum operating temperature, the control algorithm uses a reduced minimum temperature threshold, and the maximum temperature threshold may also be correspondingly reduced so that the steam generator <NUM> is then maintained around an optimum operating temperature. Such optimum operating temperature may be around <NUM> degrees Celsius.

The exemplary control scheme described above allows the steam generator <NUM> to heat up to an elevated maximum temperature threshold for the first two heating cycles upon initial heating of the steam iron <NUM>. However, the control scheme according to various embodiments is not intended to be limited to this number of initial heat cycles and the elevated maximum temperature threshold may be one or more than two cycles within the scope of the invention. Similarly, the initially elevated minimum temperature threshold of the steam generator <NUM> during the initial heating of the steam iron <NUM> may be present for more than one heat cycle within the scope of the invention. Furthermore, the control unit <NUM> of the steam iron <NUM> maybe configured to only reduce the initial maximum and/or minimum temperature thresholds of the initial heat cycles once a temperature of the ironing plate <NUM> reaches a pre-determined minimum operating temperature, which may be <NUM> degrees Celsius or may be another temperature value within the scope of the invention.

The control scheme according to various embodiments is not intended to be restricted to the specific temperature values given in the exemplary embodiment described above and other operating temperature ranges and threshold values are intended to be encompassed within the scope of the invention. In one exemplary embodiment, during the initial heat cycle(s), the steam generator <NUM> may be controlled to remain around <NUM> degrees Celsius, for example within <NUM> to <NUM> degrees either side of <NUM> degrees Celsius.

The control scheme according to various embodiments may optionally include a further function to provide an increased heating cycle of the steam generator <NUM> to an elevated heating temperature for one or more cycles before reverting to a lower operational temperature setting for the steam generator <NUM>, if it is detected that the temperature of the steam generator <NUM> falls below a lower threshold value. For example, if the steam iron <NUM> is turned off and subsequently restarted, and in the off period the steam generator <NUM> falls below a (first) predetermined temperature, then a control algorithm may be activated to set the temperature at which the steam generator <NUM> is switched off in heating cycles to an elevated (second) predetermined temperature. The steam generator <NUM> may continue to be heated to this elevated (second) predetermined temperature for a predetermined number of cycles, or until the ironing plate reaches a threshold temperature, or for a set time period. Subsequently, the control algorithm may then set the temperature at which the steam generator <NUM> is switched off in heating cycles to a reduced (third) predetermined temperature for ongoing operation of the steam iron <NUM>. In such an algorithm, the third predetermined temperature would be lower then the second predetermined temperature but higher than the first predetermined temperature. As an example, the first predetermined temperature may be <NUM> degrees Celsius. Yet further, the second predetermined temperature may be around <NUM> degrees Celsius, and/or the third predetermined temperature may be around <NUM> degrees Celsius.

In the exemplary embodiment of the steam iron <NUM> of the invention, the contact foot dimension "d" may be around <NUM> - <NUM>. Also, the thickness of the first and/or second fins <NUM>, <NUM> of the contact flange <NUM> may be around <NUM> - <NUM>. However, the invention is not intended to be limited to these dimensions and other dimensions are intended to fall within the scope of the invention.

An overall control system of the steam iron <NUM> of the invention is shown schematically in <FIG>. The controller <NUM> comprises a processor <NUM> and a memory unit <NUM>. The memory unit <NUM> may store a number of control parameters for controlling the operation of the steam iron <NUM>, such as various threshold temperatures for the steam generator <NUM> and optimum operating temperatures for the ironing plate <NUM> and/or the steam generator <NUM>. The controller <NUM> is connected to the thermistor <NUM> of the steam generator <NUM> so as to receive signals relating to the temperature of the steam generator <NUM>. Optionally, the controller <NUM> may receive signals relating to the temperature of the ironing plate <NUM>. The controller is also connected to the motion/position sensor <NUM> in the body of the steam iron <NUM> to receive a signal dependent on the position or status (i.e. in use or not) of the steam iron <NUM>. The controller <NUM> is connected to the heating element <NUM> of the steam generator <NUM> in order to be able to control operation of the heating element <NUM> in accordance with the control scheme described above.

The steam iron <NUM> of the invention, with the "damping" between heat fluctuations of the steam generator <NUM> and the passively heated ironing plate <NUM>, is more tolerant of less stable water dosing rates from the water reservoir to the steam generator <NUM>. That is, if a large amount of water is supplied to the steam generator <NUM>, a large amount of steam is produced and the body of the steam generator <NUM> cools down significantly. However, the main thermal mass of the steam generator <NUM> is lower than in known steam irons <NUM> and so the steam generator <NUM> is more quickly able to be heated up according to the set operating temperature. Also, the restricted thermal path between the steam generator <NUM> and the ironing plate <NUM> means the briefly lowered temperature of the steam generator <NUM> does not cause such a drop in the temperature of the ironing plate <NUM>. By reducing the mass of the steam generator <NUM>, the power on time of the heating element <NUM> of the steam generator <NUM> is reduced to reach a pre-determined temperature. Also, less heat is stored in the steam generator <NUM>. By also increasing the relative mass of the ironing plate <NUM>, the heat energy transferred to the ironing plate <NUM> results in lower temperature increases of the ironing plate <NUM>.

Although the steam iron <NUM> of the invention is described as having an integral water reservoir within the body <NUM> of the steam iron <NUM>, the invention is not intended to be limited to such a configuration and is intended to also encompass embodiments of steam iron which have a remote water reservoir. Such a steam iron (not shown) may comprise the steam generator within the body of the iron which is supplied with water via a water hose from a separate reservoir contained in a static base portion. The water transfer mechanism may comprise an electric pump in the body of the steam iron or in the base portion. In use, the base remains fixed and only the steam iron portion is moved across the garments by a user. Although such an alternative embodiment has a more complicated construction and occupies more space, it has the advantage that the user-moveable portion of the steam iron is lighter and easier to manipulate since it does not contain the weight of the water supply.

Although the steam iron <NUM> of the invention is described as having one thermistor <NUM> on the ironing plate <NUM>, the invention is not limited to this number and the ironing plate <NUM> may comprise a plurality of thermistors <NUM> connected to the controller <NUM>, to detect temperatures at different points on the ironing plate <NUM>.

Although the exemplary steam iron <NUM> of the invention includes a contact flange <NUM> comprising a substantially horizontal first fin <NUM> and a substantially vertical second fin <NUM>, the invention is not intended to be limited to this configuration. In particular, the second fin <NUM> may extend downwards from the first fin <NUM> at an angle to the vertical. Yet further, the invention is not intended to be limited to a contact flange <NUM> comprising an angled configuration between two separate flange portions such as the fins <NUM>, <NUM> shown and described. In an alternative embodiment within the scope of the invention, the contact flange may comprise a continuous curved shape, or a straight section transitioning into a curved shape, whilst still providing the thermal restriction between the steam generator <NUM> and the ironing plate <NUM>.

In the exemplary embodiment of steam iron <NUM> shown, the main body portion 15a of the steam generator <NUM> comprises the majority of the mass of the steam generator <NUM>, with the peripheral flange <NUM> portion of the steam generator <NUM> accounting for a much smaller proportion of the total mass of the steam generator <NUM>. In the exemplary embodiment, the mass of the main body portion 15a of the steam generator may comprise between <NUM>% to <NUM>% of the total mass of the steam generator <NUM>, and may be greater than <NUM>% of the of the total mass of the steam generator <NUM>, and yet further may be greater than <NUM>% of the total mass of the steam generator <NUM>.

The ironing plate <NUM> of the steam iron <NUM> of the invention shown and described is thicker in the region of the thermal distribution area <NUM> than over the rest of the width of the ironing plate <NUM>. This helps provide optimum heat transfer from the contact flange <NUM> across the ironing plate <NUM>. Also, the recess <NUM> of the ironing plate <NUM> upon which the contact flange <NUM> sits shown as described as being wider than the contact flange <NUM>, shown by dimension "r" indicated in <FIG> being wider than dimensions "d". Advantageously, the dimension "r" is at least <NUM> greater than the dimension "d". In particular, as the exact widths "r" and "d" may vary across the length and cross-section of the steam iron <NUM>, the average width "r" of the recess <NUM> over the whole of the ironing plate <NUM> is preferably at least <NUM> greater than the average width "d" across the whole of the steam generator contact flange <NUM>.

It will be appreciated that the term "comprising" does not exclude other elements or steps and that the indefinite article "a" or "an" does not exclude a plurality. A single processor may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to an advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Claim 1:
A steam iron (<NUM>) comprising a steam generator (<NUM>) comprising a main body portion (15a) including an electrical heating element (<NUM>) to heat the steam generator (<NUM>) and an ironing plate (<NUM>); wherein the ironing plate (<NUM>) is coupled to the steam generator (<NUM>) via a thermal coupling which comprises an indirect thermal path formed by a flange (<NUM>) which extends from a peripheral edge of the main body portion (15a) of the steam generator (<NUM>), the flange (<NUM>) being in contact with the ironing plate (<NUM>) and being spaced from the main body portion (15a) of the steam generator (<NUM>), the flange (<NUM>) also being configured to space the main body portion (15a) of the steam generator (<NUM>) from the ironing plate (<NUM>) to restrict the conduction of heat from the main body portion (15a) of the steam generator (<NUM>) to the ironing plate (<NUM>), so that the ironing plate (<NUM>) is passively heated by conduction of heat from the steam generator (<NUM>) via the thermal coupling.