US20050040153A1

US20050040153A1 - Eelectric iron

Info

Publication number: US20050040153A1
Application number: US10/956,677
Authority: US
Inventors: Carmelo Albandoz Ruiz de Ocenda; Alfred Fraunhofer
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2002-04-03
Filing date: 2004-10-01
Publication date: 2005-02-24
Also published as: CN1665977B; WO2003083202A1; CN1665977A; EP1492916A1; ES2211279A1; ES2211279B1

Abstract

An electric iron has a sole heated by a heating element and a control device for controlling the heating element. The control device includes a temperature sensor in thermal contact with the sole at a point of contact. In order to improve the thermal coupling of the point of contact to the heating element, the sole is provided with a gap that is locally defined in the area of the point of contact and a corresponding heating element segment and that reduces a heat conduction of the flow of heat emitted by the heating element in a direction away from the point of contact. The heat on the sole can thus be better controlled even if the point of contact is located either directly on or at least very close to the heating element.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuing application, under 35 U.S.C. § 120, of copending international application No. PCT/EP03/03142, filed Mar. 26, 2003, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of Spanish patent application No. 200200885, filed Apr. 3, 2002; the prior applications are herewith incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

The invention relates to an electric iron having an iron sole heated by a heating element, and having a regulating device for regulating the heating element. There is also provided a temperature sensor, which is thermally connected to the iron sole at a point of contact.
An electric iron of the generic type is known from German published patent application DE 42 12 286 A1. The electric iron comprises a metallic iron sole and a U-shaped electric resistance-heating element. The heating element is embedded in a form-fitting manner in the iron sole, which is produced by die-casting. During the operation of the iron, the heating element is supplied with electrical energy via electrical contacts at the ends of the two legs of the U-shaped heating element. The electrical energy introduced is dissipated to the iron sole in the form of heat by the heating element. A thermostat is provided in order to regulate the temperature of the iron sole, the thermostat sensing the current temperature of the iron sole and controlling a regulator, which switches the electric heating element on and off in dependence on the current temperature of the sole and on the ironing temperature preselected by the user.
For this purpose, the thermostat has a temperature sensor, which is generally formed by a bimetallic element. In order for reliable temperature regulation to take place, it has to be ensured that a change in temperature of the iron sole can be picked up directly as a change in temperature at the thermostat. The iron sole is thus usually provided with a point of contact, at which the thermostat is fastened. The point of contact generally comprises a solid dome-shaped elevation which is integrally formed directly on the iron sole.
In order that the thermostat reacts even to small temperature fluctuations in a very short period of time, and the set temperature of the iron sole is thus maintained very accurately, the above-mentioned German patent application DE 42 12 286 A1 proposes to provide a separate thermal-conduction bridge which leads from the point of contact to at least one leg of the heating element, as a result of which a greater flow of heat can be transmitted. This solution is expedient particularly in the case where the point of contact, rather than being directly adjacent to the heating element, is spaced apart from the latter by a considerable distance. The disadvantage, however, is that a separate thermal-conduction bridge which can increase the flow of heat from the heating element to the point of contact provides only insignificant improvement, if any at all, if the point of contact is arranged directly on the heating element.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an electric pressing iron, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which is further improved in terms of the thermal coupling of the point of contact with the heating element.
With the foregoing and other objects in view there is provided, in accordance with the invention, an electric iron, comprising:

- an iron sole formed with a point of contact;
- a heating element for heating the iron sole;
- a regulating device connected to the heating element and regulating the heating element, the regulating device including a temperature sensor thermally connected to the iron sole at the point of contact;
- the iron sole having a locally bounded gap formed therein in a vicinity of the point of contact and of a segment of the heat-element associated therewith, the gap reducing a thermal conduction, in a direction away from the point of contact, of a heat flow emanating from the heating element.

In other words, the objects of the invention are achieved in that the iron sole has a gap which is formed in a locally bounded manner in the region of the point of contact and of an associated heating-element section and by means of which there is at least a reduction, in a direction away from the point of contact, in the thermal conduction of the flow of heat emanating from the heating element.
By virtue of preventing, or at least reducing, the flow of heat from the heating element in a direction other than in the direction of the point of contact, an improved flow of heat in the direction of the point of contact is achieved. The flow of heat from the heating element to the point of contact is improved in that the heat generated by the heating element is preferably transported in the direction of the point of contact and transportation of heat away from the point of contact is prevented, or at least reduced. In particular during the first heating-up operation following switching on of the iron, local overheating is prevented. This most problematic instance of heating regulation is solved in a particularly effective manner by the invention in order to prevent articles for ironing from being burned. A further improvement is achieved if the outflow of heat which has already reached the point of contact is prevented, or at least reduced.
The gap is preferably arranged on a side of the heating element which is directed away from that side of the heating element which is oriented in the direction of the point of contact. The gap may thus be arranged on those sides of the heating element which are not oriented directly onto the point of contact. In a preferred embodiment of the invention, the gap is arranged on a side of the heating-element section assigned to the point of contact which is located opposite the point of contact. This position has the advantage that heat can be directed particularly effectively to the point of contact in the immediate vicinity of the heating element since the distance between this heating-element section and the point of contact is at its shortest and heat losses which would be caused by a long distance are avoided.
If the point of contact is arranged eccentrically in relation to the axis of symmetry of the U-shaped heating element in the vicinity of one of the two legs of the heating element, then the at least one opening can extend along the outer edge of this leg in the region of the point of contact. One possibility is for the gap or the at least one separate opening to be designed as a slot in the iron sole, which extends on the outside along the U-shaped heating element.
If the iron sole is constructed such that the heating element encloses the point of contact in a U-shaped manner, and a multiplicity of uniformly spaced-apart steam-outlet openings are distributed along the U-shaped heating element, the gap can be formed by at least one separate opening in the iron sole, this opening extending along an outer side of the U-shaped heating element. This has the advantage that the separate opening also performs a further function as a steam-passage opening.
By means of such a gap, in the region of the heating-element section assigned to the point of contact, the outflow of heat in the direction of the outer edge of the iron sole is prevented, or reduced. Since, despite the need for a shorter reaction time for the thermostat, as uniform heating of the iron sole as possible is necessary, a certain outflow of heat over the entire base surface of the iron sole is to be ensured. In order that the quickest possible reaction behavior of the thermostat is made possible, and uniform temperature distribution within the iron sole is also ensured, the slot can preferably extend over a length between 2 cm and 6 cm. The result is particularly advantageous and balanced if, with the conventional iron dimensions, the slot extends over a length between 3 cm and 5 cm on the outside along the U-shaped heating element. The slot essentially prevents or reduces the outflow of heat in the direction of the outer edge of the iron sole.
A second possibility by means of which the heat emanating from the heating-element section can be directed preferably in the direction of the point of contact is to define the gap as a cutout on the underside of the iron sole, the cutout extending beneath the heating-element section assigned to the point of contact. Such a gap, in the region of this heating-element section, prevents, or reduces, the outflow of heat in the direction of the base surface of the iron sole.
In order that the outflow of heat from the point of contact to the base surface of the iron sole be prevented or reduced, the gap may be formed by a cutout on the underside of the iron sole, the cutout extending beneath the point of contact. The gap here is located in the bottom of the dome-shaped point of contact.
As a result, heat which has already reached the point of contact from the heating element is not lost again by way of the base surface of the point of contact.
The heat generally transmitted laterally from the heating element to the point of contact is thus preferably directed upward in the direction of the thermostat fastened at the point of contact and the outflow of heat via the base of the point of contact into the iron sole is prevented, or reduced.
The cutout preferably has a surface area corresponding in size at least to the surface area of the point of contact. In the case of the point of contact being designed as a dome-shaped elevation, it is expedient to select the size of the surface area of the cutout to be between 4 cm²and 25 cm². In order to ensure a particularly balanced ratio between a short reaction time of the thermostat and uniform heat distribution within the iron sole, the surface area of the cutout should preferably be between 7 cm²and 17 cm².
The height of the gap should be between 0.5 mm and 5 mm. Particularly balanced results are achieved if the height of the gap is preferably between 2 mm and 4 mm. Selecting the abovementioned dimensions for the slot and cutout achieves a particularly short reaction time of the thermostat and largely uniform temperature distribution over the iron sole.
Sensitive articles for ironing can be processed without any risk of being damaged on account of non-uniform temperature distribution.
The iron sole according to the invention can have two gaps, one gap being designed as a separate opening which extends on that side of the heating-element section which is located opposite the point of contact and the other being formed as at least one cutout on the underside of the iron sole, this cutout extending beneath the heating-element section and/or the point of contact. A slot according to patent claims 3 to 5 is thus preferably combined with a cutout according to patent claims 6 to 10. These two gaps may be arranged such that they are connected to one another at at least one location, i.e. the gaps merge into one another.
The thermal-isolation action of the heating-element section is thus particularly effective since there are no crosspieces remaining between the two gaps which could dissipate heat.
The invention, rather than being restricted to electric steam iron also covers dry electric irons. It is possible for the iron soles of the electric irons according to the invention to consist of different materials, in particular of die-cast aluminum, and to be optionally provided with a separate sole. The sole here may consist preferably of stainless steel, of aluminum or be treated with enamel or ceramic material. If the iron sole has a sole which is fastened on the underside of the iron sole and is in surface contact with the latter, one side of the cutout according to the invention or of the gap is bounded by the sole.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electric iron, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective bottom view of an iron sole according to the invention;
FIG. 2 is a perspective to view of the iron sole according to FIG. 1;
FIG. 3 is a partly diagrammatic cross section through an iron according to the invention; and
FIG. 4 is a cross section through the iron sole according to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown an iron sole 1, viewed from the bottom. An electric resistance-heating element 3 is cast into the iron sole 1, which is produced by aluminum die-casting. The heating element 3 is of U-shaped configuration and extends along steam-passage openings 7 which connects a steam chamber 8 to the underside of the iron sole 1. Terminal ends 9 and 10 of the two legs of the U-shaped heating element 3 project out of the steam chamber 8 and carry the required electrical contacts.
Within the steam chamber 8, a dome-shaped point of contact 6 is cast onto the iron sole 1. The point of contact 6 forms a pedestal to which a temperature sensor 5 of a regulating device 4 is contact-connected. The dome-shaped point of contact 6 is directly adjacent to a heating-element section 14 of one leg of the U-shaped heating element 3. The dome-shaped point of contact 6 rises up on the top side of the iron sole 1. Beneath the dome-shaped point of contact 6, the gap 2 b is located on the underside of the iron sole 1. The gap 2 b is designed as a cutout on the underside of the iron sole 1. The gap 2 b is of substantially rectangular design and has a surface area measuring 4.5 cm×3 cm. The gap 2 b, as is illustrated in FIG. 1, thus has a surface area of 13.5 cm².
FIG. 2 shows the top side of the iron sole 1 according to the invention. The gap 2 a is configured as a slot in the iron sole 1. This gap 2 a extends on the outside along one leg of the U-shaped heating element 3. The slot 2 a extends along a number of the steam-outlet openings 7 in the vicinity of the dome-shaped point of contact 6. The slot 2 a is located on the opposite side of the leg of the heating-element 3 on which the dome-shaped point of contact 6 is adjacent to the heating-element section 14 of the U-shaped heating element 3. The slot 2 a extends along an outer side 15 of the U-shaped heating element 3 over a length of 4.5 cm.
FIG. 3 shows the cross section through the iron sole 1 according to the invention. The dome-shaped point of contact 6 is cast on the iron sole 1, which is produced by aluminum die-casting. At the dome-shaped point of contact 6, the temperature sensor 5, which is designed in a conventional construction as a bimetallic element, is thermally coupled to the iron sole 1. The temperature sensor 5 is connected to the regulating device 4, which is fitted in a housing 12 of the iron via a rotary knob 13. The gap 2 b is formed beneath the dome-shaped point of contact 6, as seen in the cross section of the iron sole 1. The gap 2 a, which is formed as a slot or an oblong hole, directly adjoins the gap 2 b, which is formed as a cutout.
As can be seen from FIG. 4, the gap 2 a, which is designed as a slot, is connected directly to the gap 2 b, which is designed as a cutout. The gap 2 b, which is designed as a cutout, thus extends both beneath the heating element 3 and beneath the point of contact 6.
The gaps 2 a and 2 b according to the invention can be used in principle in steam irons and also in dry irons. The gaps 2 a and 2 b are preferably used in steam irons which have the iron sole 1, as is illustrated in FIG. 3, covered by a soleplate 11. The soleplate 11 here bounds the underside of the gap 2 b, which is designed as a cutout, and is in surface contact with the underside of the iron sole 1. This results in a continuous ironing surface which rests on the article for ironing, and the thermal isolation of the dome-shaped point of contact 6 is ensured.

Claims

1. An electric iron, comprising:

an iron sole formed with a point of contact;

a heating element for heating said iron sole;

a regulating device connected to said heating element and regulating said heating element, said regulating device including a temperature sensor thermally connected to said iron sole at said point of contact;

said iron sole having a locally bounded gap formed therein in a vicinity of said point of contact and of a segment of said heat-element associated therewith, said gap reducing a thermal conduction, in a direction away from said point of contact, of a heat flow emanating from said heating element.

2. The electric iron according to claim 1, wherein said gap is formed on a side of said heating-element segment opposite from said point of contact.

3. The electric iron according to claim 2, wherein said heating element encloses said point of contact in a U-shape, and said sole is formed with a multiplicity of uniformly spaced-apart steam-outlet openings distributed along said U-shaped heating element, and said gap includes at least one separate opening formed in said iron sole, and said separate opening extends along an outer side of said U-shaped heating element.

4. The electric iron according to claim 3, wherein said point of contact is disposed eccentrically in relation to an axis of symmetry of said U-shaped heating element in a vicinity of one of two legs of said heating element, and said at least one separate opening extends along an outer edge of said one leg in a region of said point of contact.

5. The electric iron according to claim 4, wherein said at least one separate opening is a slot extending along the outer side over a length of between 2 cm and 6 cm.

6. The electric iron according to claim 4, wherein said at least one separate opening is a slot extending along the outer side over a length of between 3 cm and 5 cm.

7. The electric iron according to claim 1, wherein said gap is a cutout on an underside of the iron sole, and said cutout extends beneath said point of contact.

8. The electric iron according to claim 1, wherein said gap includes a first cutout formed in an underside of said iron sole, and extending beneath said heating-element segment.

9. The electric iron according to claim 8, wherein said gap further includes a second cutout in the underside of said iron sole, and said second cutout extends beneath said point of contact.

10. The electric iron according to claim 9, wherein said second cutout has a surface area corresponding in size at least to a surface area of said point of contact.

11. The electric iron according to claim 10, wherein the surface area of said second cutout is between 4 cm²and 25 cm².

12. The electric iron according to claim 10, wherein the surface area of said second cutout is between 7 cm²and 17 cm².

13. The electric iron according to claim 9, wherein a height of one of said first cutout and said second cutout lies between 0.5 mm and 5 mm.

14. The electric iron according to claim 13, wherein the height lies between 2 mm and 4 mm.

15. The electric iron according to claim 1, wherein said gap is one of two gaps including a first gap formed as a separate opening extending on a side of said heating-element segment opposite said point of contact, and including a second gap formed as at least one cutout on an underside of said iron sole.

16. The electric iron according to claim 15, wherein said at least one cutout extends beneath said heating-element segment and beneath one or both of said heating-element segment and said point of contact.

17. The electric iron according to claim 15, wherein said two gaps are connected to one another.