EP0719886A1 - Iron with a thermal detector for measuring the fabric temperature - Google Patents

Abstract

The smoothing iron has a sole plate (11) for sliding over the fabric, a heater, and a thermal detector (13) for measuring the temp. of the fabric during ironing, and adjusting the temp. accordingly. The detector is fixed to the sole plate and insulated form it by a supple cellular plate (110) with a low level of effusion. The plate is designed to keep the detector thermally isolated form the sole plate and to press it flexibly against the fabric being ironed. It is connected to the sole plate by a rigid, thermally-insulating support (120). The cellular plate can be made from felt, low density silicon foam, a honeycomb material, or a combination of felt and honeycomb material. The support can be in two sections, made form materials with different levels of rigidity. The detector can be coated with a thin layer of polyimide or Teflon (RTM).

Description

The invention relates to an iron comprising a soleplate intended to slide on a fabric, heating means for heating the soleplate, a thermal detector for measuring a temperature of the fabric during ironing operations and for monitoring the iron. , fixing means for securing the detector to the sole by thermally insulating it.

Commercial irons measure the temperature of the soleplate, not the temperature of the fabric itself. This is due to the fact that it is indeed difficult to measure a fabric temperature without it being at least partially influenced by the temperature of the sole. However, controlling the temperature of the fabric during ironing is an important parameter for obtaining good ironing quality.

Document JP 4-5998 describes an iron comprising in particular a thermal detector for measuring the temperature of a fabric during ironing. The detector is inserted into the soleplate of the iron. So that the detector is not too strongly influenced by the temperature of the soleplate, a thermal shield is placed around the detector. The constitution of the thermal shielding is not revealed in the document.

When a thermal detector, operating in contact with the fabric, is placed on the fabric, the temperature of the thermal detector should tend to equilibrate with that of the fabric. However, this balance can be disturbed by the high temperature of the sole which brings significant thermal disturbances.

In addition, it is during the sliding of the iron on the fabric that the temperature measurement of the fabric must be carried out. The iron cannot remain stationary at the risk of burning the fabric. Therefore, for the control of the parameters of the iron, the response times of the detectors must be very short. The detector must therefore have a low thermal inertia without being vulnerable to thermal inputs from the sole. he It is therefore not permissible for the temperature of the detector to be influenced too much, in dynamic regime and in static regime, by the temperature of the soleplate.

To these problems, linked to heat exchanges, are added several types of mechanical problems. First, mechanical resistance problems of the detector which must be resolved without weakening the detector by significant and repeated bending of the substrate supporting the detector. Second, mechanical problems related to the size. On the one hand, the detector must be inserted in a sole having a few millimeters of thickness. On the other hand, the existence of the heating element, the water reserve, the steam conduits, etc, leave only little space to fix the detector and to solve the problems of heat exchanges.

It is therefore difficult to meet all these requirements at the same time and this partly explains the reasons why commercial irons are not equipped with a thermal fabric detector.

The object of the invention is therefore to meet these requirements with the aid of specific fixing means, of low cost, making it possible to subject the thermal detector to the soleplate of the iron.

For this, the fastening means comprise a flexible dimpled blade of low effusiveness, the blade being intended to keep the detector thermally isolated from the sole and to press the detector flexibly against the fabric during ironing, the dimpled blade being subject to the sole. by a rigid thermal insulating support.

The fixing means are thus rigid enough to avoid significant bending of the detector, which prevents any embrittlement, while correctly applying the detector to the fabric to ensure good thermal contact.

Low effusiveness is characterized by low thermal conductivity, low specific mass, low heat capacity.

At the end of a period during which the thermal detector, placed in the hot soleplate, has not been brought into contact with the fabric, it can be observed that the thermal detector takes an equilibrium temperature closer to the temperature of the sole (generally significantly higher than 100 ° C) than the temperature of the fabric (generally close to room temperature). When ironing starts, the temperature of the detector must drop very quickly to the temperature of the fabric. According to the invention, the time constant of the detector is around 0.1 to 0.4 seconds.

• grâce aux faibles capacités calorifiques mises en jeu et à la faible effusivité des moyens de fixation, l'ensemble dispose d'un temps de réponse rapide et d'une aptitude à fournir une mesure adéquate de la température des tissus dans la gamme utile de température pour un contrôle d'un fer à repasser à vapeur : typiquement à partir d'environ 90°C et au-dessus,
• très bonne isolation thermique entre le détecteur thermique et la semelle du fer,
• très bon comportement du détecteur thermique et de l'isolation thermique jusqu'à des températures de la semelle de l'ordre de 200°C qui sont celles qui peuvent être mesurées sur la semelle du fer. Ainsi les moyens de fixation assurent un faible temps de réponse et une faible inertie thermique au détecteur et un contact à pression souple grâce à la lame souple alvéolée. Une rigidité d'ensemble est obtenue grâce au support assurant la robustesse de l'ensemble détecteur/moyens de fixation.

According to the invention, the assembly formed by the thermal detector and by the fixing means has the following advantages:

• thanks to the low heat capacities involved and the low effusiveness of the fixing means, the assembly has a rapid response time and an ability to provide an adequate measurement of the temperature of the tissues in the useful temperature range. for checking a steam iron: typically from around 90 ° C and above,
• very good thermal insulation between the thermal detector and the soleplate of the iron,
• very good behavior of the thermal detector and thermal insulation up to soleplate temperatures of the order of 200 ° C. which are those which can be measured on the soleplate of the iron. Thus, the fixing means ensure a short response time and low thermal inertia to the detector and a contact with flexible pressure thanks to the flexible honeycomb blade. Overall rigidity is obtained thanks to the support ensuring the robustness of the detector / fixing means assembly.

These characteristics are maintained even after a long ironing session because there is only a slight accumulation of heat in the dimpled blade.

Preferably, the honeycomb blade is embedded in the support to thermally isolate it laterally from the sole and improve its mechanical strength. Thus the fixing means give good lateral insulation of the detector parallel to the plane of the sole.

To protect the detector from wear phenomena and to ensure a good seal, in particular against water vapor, the detector is coated with a thin protective layer. This layer can cover the support, at least partially, to seal between the detector and the support.

These different aspects of the invention and others will be apparent and elucidated from the embodiments described below.

The invention will be better understood using the following figures given by way of non-limiting examples which represent:

Figure 1: a diagram of an iron fitted with a thermal detector.

Figure 2: a diagram of a first embodiment of the fixing means of the thermal detector according to the invention.

Figure 3: a diagram of a second embodiment of the fastening means of the thermal detector according to the invention.

Figure 4: a diagram of a particular embodiment corresponding to the second mode.

Figure 5: a sectional view of a detector placed in fixing means which give the detector a slightly domed shape towards the outside.

FIG. 1 represents an iron 10 of known type comprising a soleplate 11, heating means 12, a thermal detector 13 and fixing means 14 which join the detector 13 to the soleplate 11 by thermally insulating them from one the other. The thermal detector is used to regulate the heating means and / or the emission of steam in the case of a steam iron.

• souplesse du contact détecteur-tissu,
• isolation thermique du détecteur,
• tenue mécanique et tenue aux températures élevées de l'ensemble,
• encombrement réduit imposé par la faible épaisseur de la semelle et par l'existence des éléments chauffants, réserve d'eau, conduits de vapeur, etc.

In FIG. 2 are shown, according to the invention, the fixing means 14 of the detector 13. By combining a dimpled blade 110 with a support 120, the invention provides an answer to the problems of:

• flexibility of the detector-tissue contact,
• thermal insulation of the detector,
• mechanical strength and resistance to high temperatures of the assembly,
• reduced overall dimensions imposed by the small thickness of the soleplate and by the existence of heating elements, water reserve, steam conduits, etc.

The honeycomb blade 110 is formed of a first flexible and thermal insulating material, such as a felt, having by its constitution a honeycomb structure therefore very ventilated providing both the required flexibility and the required thermal insulation. Felt has the advantage of being a very good thermal insulator. The temperature of the felt can rise above 100 ° C when the felt is not in contact with the fabric. Thanks to its low heat capacity involved and its low effusiveness, it allows the detector to return very quickly to a temperature close to that of the fabric. Other cellular materials can also be used, for example a very low density silicone foam (0.1 to 0.2 approximately) or materials with a honeycomb structure such as the polyaramide material called "Nomex" *. They can be used alone or preferably in combination with a felt which provides additional flexibility. In addition, the felt prevents the detector from being damaged by direct contact with the honeycomb. The felt may itself be provided with an interlayer, for example a polyimide sheet, to prevent the honeycomb material from piercing the felt. Commercial felts can be used which resist temperatures up to around 250 ° C and have a very low density of the order of about 0.1 to 0.2.
* trademark

Used alone, a felt-based support does not have sufficient mechanical properties to be mounted and held in isolation on an iron soleplate without the detector being damaged either during assembly or during use.

To overcome this difficulty, we place the blade of felt (approximately a few millimeters thick) on a support 120 which provides the required mechanical rigidity and satisfactory additional thermal insulation. This support is for example made of "Teflon" *, a material which is suitable for the range of temperatures usually encountered with an iron.
* trademark

One face of the honeycomb blade 110 receives the detector 13 which is maintained for example by pressure or by bonding. On the face directed towards the fabric, the detector 13 is covered with a protective layer 150 of small thickness, for example made of polyimide, to ensure the sealing and the mechanical protection of the detector. To avoid heat transfer in the layer 150 to the sensitive element of the detector, it is desirable that the distance between the sensitive element of the detector and the soleplate of the iron, parallel to the soleplate, is large enough to have a gradient high thermal, of the order of 50 ° C to 80 ° c for example, between the sensitive element and the sole. The other face of the blade 110 is also held by pressure on the support 120. At the interface between the detector and the felt, a thin intermediate sheet 140 can be placed to prevent the detector from rubbing against the felt. The detector being generally deposited on a substrate, the latter can constitute either the protective layer 150 or the interlayer sheet 140 depending on the mounting direction given to the detector. The support 120 is provided with a tip 130 intended to pass through the sole 11. The tip is provided with a passage for guiding and isolating electrical connections 15 connected to the detector 13.

One side B of the sole is in contact with the fabric. Another face A of the sole is in contact at least in part with a reserve of water (not shown), the water transforming into vapor on contact with the sole. The steam thus produced passes, during ironing, through the soleplate through orifices 17. The support 120 provided with its tip 130 must ensure the water vapor tightness on the side of the side A. This is obtained, for example, by forcing it slightly into the sole and / or by gluing the support. The mechanical strength of the support therefore serves both to ensure a rigid and waterproof attachment with the sole and to maintain the blade.

The honeycomb blade being quite fragile, it is therefore avoided to open it on the side of side B. Therefore, to obtain a correct lateral thermal insulation, preferably the blade is embedded in the support. The protective layer 150 is then extended to cover the junction between the blade and the support in order to prevent the passage of moisture or water vapor.

The combination of the blade and the rigid support therefore provides an optimal solution to the problems encountered in fixing a thermal detector to the soleplate of an iron. This combination combines a honeycomb blade of very low effusiveness and of low heat capacity but which does not necessarily have good mechanical qualities, with a support having very good mechanical qualities but which is not necessarily as good a thermal insulator as the felt, and which, if used alone, would not be sufficient to meet the requirements.

In order to obtain reliable measurements of the temperature of the fabric, it is desirable to reduce the heat capacity of the fixing means as much as possible. This reduction can lead to reducing the dimensions of the fixing means. It may then happen that the desirable thickness to be given to the support becomes so small that its mechanical qualities are reduced. This problem is solved by making the support in two parts: a first part having as preponderant quality its thermal insulation and a second part having as preponderant quality its mechanical rigidity. The material forming the second part is then selected for its good rigidity even at small thicknesses.

Such an embodiment is shown in Figure 3. The support 120 is then formed of two parts: an external part 124, in contact with the sole, chosen first for its qualities of insulation, but nevertheless rigid, for example Teflon, and an internal part 122, in contact with the blade 110, formed by a material chosen in the first place for its qualities of rigidity, for example Celeron *. This last material, in particular, retains a very good rigidity even for a very small thickness and this even after long periods of maintenance at high temperature. Its thermal insulation qualities are nevertheless less good than those of Teflon. It is also more suitable for receiving the protective layer 150 by bonding. The complementarity of these two materials makes it possible to obtain a support having sufficient thermal insulation and sufficient mechanical rigidity even for a very small thickness, therefore for a low capacity. calorific.
* trademark

It is also possible to reduce the heat capacity of the fixing means, to reduce the response time of the detector, and to obtain a more correct measurement of the temperature of the tissue by making recesses both in the support formed of a single part. (Figure 2) in the support formed by two parts (Figure 3) to reduce the bearing surfaces of the elements between them to reduce heat exchange.

An exemplary embodiment in the case where the support is formed of two parts is shown in FIG. 4. The external part 124 and the internal part 122 have recesses 125 which lighten each of the parts on their peripheries. The heat exchanges between the external part 124 and the internal part 122 on the one hand and the heat exchanges between the external part 124 and the sole 11 on the other hand, are thus reduced. It is also possible to make recesses inside the external part 124. Other ways of reducing the bearing surfaces can be envisaged by a person skilled in the art. In order to reduce the heating by radiation coming from the sole, the surfaces of the supports 124 and 122 can be made reflective, in particular those facing the sole. This can be achieved by depositing a reflective layer in the infrared (aluminum, gold) for example by evaporation.

Although this is not apparent in Figure 4, it should be understood that the protective layer 150 is slightly flush with the outside of the sole 11. This arrangement is provided so that during ironing the detector 13 can be applied, for example. through the protective layer 150, on the fabric to be ironed. It is possible to promote this contact with the fabric by giving the blade 110 a slightly domed shape, for example in its center. In a particular embodiment, this case is shown in the diagram in Figure 5 which shows a section of the fixing means in a perspective view. The fixing means have a general shape of cylindrical appearance with a circular base. The external part 124 of the support has the appearance of a cup (inverted in FIG. 5) filled with another cup 122 in Celeron, itself filled with a honeycomb material 123 forming the internal part. The felt 110 is positioned on the material 123. It is preferable to place a thin sheet of polyimide between the felt and the honeycomb part to avoid damaging the felt blade. This felt is slightly put in compression by the pressure exerted by the protective layer 150 bonded to the external part 124. The felt has, in its center, a domed shape giving it an elasticity effect. On this felt are fixed respectively, a thin interlayer sheet 140 (FIG. 4) (not shown in FIG. 5 but which can be the substrate of the detector), the thermal detector 13 and the protective layer 150. Thus when the iron slides on the fabric, and despite the surface irregularities of the latter, the detector remains in constant thermal contact allowing a reliable measurement of the temperature of the fabric.

To provide an adequate measurement of the fabric temperature and have a short response time, the detector must have a low heat capacity. It may be a surface temperature detector formed of a sensitive element such as a resistive layer deposited for example on a substrate formed of a thin sheet of polyimide by a thick layer or thin layer technique, or d 'a resistive layer maintained by gluing for example. It can also be sensitive elements such as surface thermocouples formed, for example, thin or thick layers deposited by appropriate techniques. The thin sheet used must be able to withstand temperatures of the order of 100 ° C. without being deformed and even above it because of the heating generated by the soleplate of the iron. The thin sheet must have a sufficiently low heat capacity so as not to disturb the temperature measurement. Thin sheets of polyimide or Teflon 20 to 100 micrometers thick are suitable for this use.

Claims (8)

Iron comprising a soleplate (11) for sliding on a fabric, heating means (12) for heating the soleplate, a thermal detector (13) for measuring a temperature of the fabric during ironing operations and for monitoring the iron, fixing means (14) for securing the detector to the soleplate by thermally insulating it characterized in that the fixing means comprise a flexible honeycomb blade (110) of low effusiveness, the blade being intended to keep the detector thermally insulated from the sole and to press the detector flexibly against the fabric during ironing, the dimpled blade being secured to the sole by a rigid thermal insulating support (120). Iron according to claim 1 characterized in that the honeycomb blade is chosen from: a felt blade, a low density silicone foam, a honeycomb blade, or a felt / honeycomb combination. Iron according to one of claims 1 or 2 characterized in that the blister blade is embedded in the support to isolate the blade thermally and laterally from the sole. Iron according to one of claims 1 to 3 characterized in that the support has limited bearing surfaces to reduce heat exchange with the soleplate. Iron according to claim 4 characterized in that the support comprises two parts (122, 124) formed of materials of different rigidity. Iron according to one of claims 1 to 5 characterized in that the detector is provided with a protective layer (150) of small thickness to ensure the sealing and the mechanical protection of the detector. Iron according to one of claims 1 to 6 characterized in that the honeycomb blade gives the detector a slightly domed shape towards the outside. Iron according to one of Claims 1 to 7, characterized in that the thermal detector has a low heat capacity, the thermal detector comprising either resistive sensitive elements on thin support, ie sensitive elements formed of surface thermocouples.

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