WO2008066418A1

WO2008066418A1 - Heating device

Info

Publication number: WO2008066418A1
Application number: PCT/SE2006/001360
Authority: WO
Inventors: Simon Pierre
Original assignee: Aktiebolaget Electrolux
Priority date: 2006-11-29
Filing date: 2006-11-29
Publication date: 2008-06-05
Also published as: ATE532896T1; EP2092105A4; EP2092105A1; DK2092105T3; EP2092105B1

Abstract

The present invention relates to a heating device for laundry washing machines, comprising a tubular heating body, and a cover plate. The tubular heating body comprises a loop portion having a breadth, a length and a height. The cover plate comprises a main surface having a longitudinal and transverse delimitation, and two side surfaces located at and along one longitudinal delimitation of the main surface respectively. The cover plate is attached to the tubular heating body, the main surface of the cover plate extends over the breadth of the loop portion and at least along a major length of the loop portion, and the side surfaces of the cover plate extend over the height of the loop portion, whereby the cover plate partially embraces the loop portion of the tubular heating body along the at least major length thereof. The present also relates to a laundry washing machine including such a heating device .

Description

HEATING DEVICE

Technical Field of the Invention

The present invention relates to a heating device for a laundry washing machine and to a laundry washing machine including such a heating device.

Background Art

In most laundry washing machines, the washing liquid is heated for obtaining the desired washing temperature. For this purpose, it is known to use electric resistor heating elements, which are flooded by the washing liquid when the washing machine is running. A conventional resistor heater normally has a tubular heating body, which is laid out in one or several loops at the bottom of the washing machine. A problem associated with such electric heaters is that filamentary material, such as threads, lint, fluff and the like, that come loose from the laundry can get caught on the tubular body of the heaters. This will cause even more filamentary material to entangle and gather around the resistor heaters at the bottom of the washing machine. Since the outlet for discharging the washing liquid is located at the bottom of the machine, the accumulated filamentary material may eventually block the outlet. This problem is especially experienced with professional washing machines for washing cleaning mops.

DE 197 49 958 B4 discloses a washing machine heater comprising a tubular resistor heater that is embedded in a block of an aluminium alloy. A problem with this known heater is that aluminium cannot satisfactory withstand the tough conditions in the washing liquid.

Summary of the Invention

It is therefore an object of the present invention to provide a heating device for laundry washing machines that alleviates the above-mentioned problems. According to the invention this object is achieved by a heating device according to claim 1.

A heating device for laundry washing machines according to the invention comprises a tubular heating body and a cover plate. The tubular heating body comprises a loop portion that has a breadth, a length and a height. The cover plate comprises a main surface that has a longitudinal and transverse delimitation, and two side surfaces located at and along one longitudinal delimitation of the main surface respectively. The cover plate is attached to the tubular heating body, the main surface of the cover plate extends over the breadth of the loop portion and at least along a major length of the loop portion, and the side surfaces extend over the height of the loop portion, whereby the cover plate partially embraces the loop portion of the tubular heating body along the at least major length thereof.

When the heating device according to the invention is properly positioned in a washing machine, loose filamentary material in the washing liqμid flowing passed the heating device will, due to the configuration of the cover plate according to the invention, slip over the cover plate and not entangle with the tubular heating body. At the same time, the tubular heating body will be in direct contact with the washing liquid below the cover plate such that the heat of the tubular heating body is directly transferred to the washing liquid. Thus the choice of material for the cover plate is not limited to materials having good heat conductivity, whereby a material suitable with regard to the conditions in the washing liquid and to the manufacturing process can be used for the cover plate.

The heating device according to the invention is suitable for being used in a washing machine for washing textiles that are likely to lose filamentary material such as threads, lint, fluff and the like, and especially in professional machines for washing cleaning mops . The washing machine can be of any conventional type, for example a front-loaded washing machine having an inner tub that is rotatably supported in a stationary outer tub. According to the invention, the heating device is of a kind including a tubular heating body, for example an electric resistor heater.

According to the invention, the tubular heating body can have a circular, rectangular or any other suitable cross section.

According to the invention, the tubular heating body is configured in one or several loop at a loop portion. By loop is meant that the tubular heating body forms a closed or partly open curve within itself. Normally, the respective end portion of the tubular heating body that enters respectively exits the loop portion are substantially pointing in the same direction such that the end portions can be connected to a suitable power source at one side of the loop portion. According to the invention, the cover plate can be attached to the tubular heating body in any suitable manner, for example by using a fastener such as a clip, a nail or a screw, by welding or by using interlocking shapes of or friction between the cover plate and the tubular heating body.

At the loop portion, the tubular heating body forms a package having a breadth, a length and a height.

According to the invention, the cover plate has a main surface and two side surfaces and is arranged on the tubular heating body such that the cover plate partly embraces the loop portion while leaving an opening for the washing liquid between the edges of the side surfaces. The cover plate partially embraces the loop portion along a major length of the loop portion. According to the invention, the main surface and the two side surfaces can be one integral curved surface. It is also possible that the side surfaces protrude in an angle from the main surface. The main surface has a longitudinal and a transversal extension in order to cover at least one side of the loop portion along at least a major portion of the length thereof. The side surfaces are located along a longitudinal delimitation of the main surface and extend in the longitudinal direction of the main surface and cover the height of the loop portion. Thereby it is ensured that any filamentary material in the washing liquid will slip over the cover plate of the heating device when it is immersed in the washing liquid.

According to one embodiment of the invention the side surfaces are provided with one flange respectively, which flanges prolongs the side surfaces to reach in under the loop portion on the side thereof that is opposite to the main surface. However, the cover plate with the main surface, the side surfaces and the flanges do not completely surround the loop portion, such that washing liquid is able to flow in between the flanges and contact the tubular heating body.

According to the invention, it is not necessary that the cover plate covers the loop portion along the entire length thereof, it is sufficient if the loop portion is covered to an extent that a gathering of filamentary material large enough to block the outlet or damage the washing machine in other ways is prevented.

According to one embodiment of the invention, the cover plate is made of stainless steel, which is a material suitable for withstanding the corrosive conditions in the washing liquid. It has not been possible to use stainless steel for the moulded covers of the prior art, since the high temperatures needed for moulding stainless steel would damage the tubular heater. According to one embodiment of the invention, the tubular heating body is arranged in at least one U-shaped loop at the loop portion. Several loops can be arranged helically on top of each other or in a curve side by side.

According to one embodiment of the invention, the heating device is included in a washing machine. The heating device is inserted through an opening at the bottom of the washing machine and subsequently the proximal end of the loop portion is fastened at the opening. A watertight seal is provided at the opening such that electrical connection terminals of the tubular heating body are separated from the washing liquid.

According to one embodiment, the loop portion and the cover plate are configured to fit the geometrical restrictions of the opening and at the bottom of the washing machine such that the heating device can be removed and replaced in case of repairs or failure.

According to one embodiment, the washing machine is provided with a securing plate under which a distal, not covered end of the loop portion is inserted. The cover plate according to this embodiment extends from the proximal end of the loop portion to the edge of the securing plate when the heating device in mounted in the washing machine. Consequently, substantially the entire length and height of the loop portion are covered.

Brief Description of the Drawings

The invention may be performed in many different ways, and by way of example only, embodiments thereof will now be described in detail with reference being made to the accompanying drawings, in which: Fig. 1 is an exploded view of interior parts of a washing machine including a heating device according to a first embodiment of the invention;

Fig. 2 is a perspective view from above of the heating device according to the first embodiment of the invention; Fig. 3 is a perspective view from below of the heating device according to the first embodiment of the invention;

Fig. 4 is a perspective view from below of a heating device according to a second embodiment of the invention; Fig. 5 is a perspective view from below of a heating device according to a third embodiment of the invention;

Fig. 6 is a sectional view of the heating device according to the third embodiment of the invention; Fig. 7 is a sectional view of a heating device according to a fourth embodiment of the invention;

. ^' Fig. 8 is a sectional view of a heating device according to a fifth embodiment of the invention;

Fig. 9 is a perspective view of a bottom of a washing machine including three heating devices according to the first ^■ embodiment of the invention.

Detailed Description of Preferred Embodiments of the Invention . With reference to Figs. 2 and 3, a first embodiment of the heating device according to the invention is shown. The heating device includes an electric resistor heater element comprising a tubular heating body 1. The tubular heating body 1 has a circular cross section and is arranged in one U-shaped loop forming a loop portion. Thus, the tubular heating body 1 forms a partly open curve within itself.

The heating device further comprises a cover plate 2, which is attached to the tubular heating body 1. The cover plate 2 comprises a main surface 3, which has a breadth corresponding to the breadth of the loop portion and a length leaving the interconnecting curve of the U- shaped loop uncovered. Two side surfaces 4 extend substantially perpendicular from the main surface at one longitudinal side thereof respectively and cover the height of the loop portion, i.e. in this embodiment, the thickness of the tubular heating body 1. The transitional area 17, where the side surfaces 4 meet the main surface 3, has a curved shape. Each of the two side surfaces 4 is provided with one flange 5 extending a small distance on the side of the loop portion that is opposite to the main surface 3. Thus, the cover plate 2 including the main surface 3, the side surfaces 4 and the flanges 5 partially embrace the two legs of the U-shaped tubular heating body 1 of the loop portion along a major length thereof. The cover plate is attached to the tubular heating body 1 by a fastener in the form of a clip 14, which is welded to the cover plate 2. The clip 14 includes two semicircular end portions for engagement with the tubular heating body 1. Consequently, the cover plate can be manufactured by bending and cutting a metal sheet of for example stainless steel. Thereafter, a fastener can be welded to the cover plate for enabling attachment to the tubular heating body. At the ends of the legs of the U-shaped portion of the tubular heating body, a sealing 6 is arranged. On the side of the sealing 6 that is opposite to the loop portion, the leg ends are provided with electrical connection terminals 7 for connection to a power source via electric wires 11.

With reference to Figs 1 and 9, the heating device according to the first embodiment of the invention is shown in connection with a laundry washing machine, wherein only an interior part of the washing machine is shown. The laundry machine according to the described embodiment comprises an outer tub 8 and an inner tub 9, which is rotatably mounted in the outer tub 8. The outer tub 8 is provided with a bottom trough 10, which has an outlet opening 12 for discharging the washing liquid. At a rear portion, the bottom trough 10 of the outer tub 8 is equipped with a securing device in the form of a corrugated plate 13. The corrugated plate 13 is provided with guide flanges 16. At the front wall of the bottom through 10, there are three holes 15 for three heating devices respectively.

The first embodiment of the heating device according to the invention functions in the following way.

The cover plate 2 is attached to the tubular heating body 1 by snapping the clips around the leg portions of the U-shaped loop, wherein the interconnecting curved portion of the U-shaped loop protrudes out of the cover plate 2. Thereafter, the heating device is inserted between the inner tub 9 and the outer tub 8 of the washing machine through one of the holes 15. When the heating device reaches the corrugated plate 13, it is guided by the guide flanges 16 into a casing formed by the corrugated plate 13 and the bottom of the through 10. Then the heating device is positioned with the sealing 6 in the hole 15 and locked in this position by for example a locking screw (not shown) . Finally, the electric terminals 7 are connected to a power source (not shown) via the electric wires 11.

Due to the corrugated plate, the heating device is prevented from contacting the rotating inner tub when the washing machine is running. Furthermore, the corrugate plate covers the uncovered, protruding portion of the loop portion, such that substantially the entire length of the loop portion is covered when the heating device is positioned in the washing machine.

When the washing machine is running, the heating device is flooded under the washing liquid such the tubular heating body 1 is able to directly transfer heat to the washing liquid. If any filamentary material is present in the washing liquid, it will flow against the cover plate, which will force the filamentary material to slip pass the heating device either above or under the loop portion. This property of the cover plate is enhanced by the curved transitional area 17 and by the flanges 5. If necessary, for example for repairs, the heating device can easily be removed by disconnecting the heating device from the power source, unlocking the locking screw an pulling the heating device out of the hole 15. In Fig. 4 and 5 alternative embodiments of the heating device according to invention are shown. The embodiment according to Fig. 4 differs from the first embodiment described above substantially only in that the loop portion of the tubular heating body 1 comprises two loops arranged side by side. The embodiment according to Fig. 5 differs from the first embodiment described above substantially only in that the ^' loop portion of the tubular heating body 1 comprises two loops, which are arranged helically on top of each other. Both these alternative embodiments can be included in a washing machine in the same manner as the first embodiment described above.

In Fig. 6 a sectional view of the heating device according to Fig. 5 is shown. The cover plate 2 partially embraces the tubular heating body 1 at the loop portion by means of the main surface 3, the side surfaces 4, the curved transitional areas 17 and the flanges 5. In addition, the cross section of the clip 14 can be seen in Fig. 6. The clip 14 is welded to the main surfaces 3 and reaches around two opposed leg portions of the U-shaped loop from within the U-shaped loop to hold the tubular heating body 1.

In figs. 7 and 8 further alternative embodiments of the heating device according to invention are shown. In Figs .7 and 8, a cross section- of the respective heating device is shown, wherein the fastener is not visible although present in these embodiments too. The embodiment according to Fig. 7 has a loop portion with the same configuration as the embodiment according to Fig. 5 and 6. The embodiment according to Fig. 7 differs from the embodiment described above with reference to Figs . 5 and 6 substantially only in that the cover plate 2 has a curved cross section. The embodiment according to Fig. 8 differs from the first embodiment described above substantially only in that the loop portion of the tubular heating body 1 comprises two loops, which are arranged in two levels, and in that the cover plate 2 has a different cross section. The main surface according to this embodiment includes two angled parts 3a, 3b. Also these alternative embodiments can be included in a washing machine in the same manner as the first embodiment described above.

Claims

1. A heating device for laundry washing machines, comprising a tubular heating body, which comprises a loop portion having a breadth, a length and a height, and a cover plate, which comprises a main surface having a longitudinal and transverse delimitation, and two side surfaces located at and along one longitudinal delimitation of the main surface respectively, wherein the cover plate is attached to the tubular heating body, the main surface of the cover plate extends over the breadth of the loop portion and at least along a major length of the loop portion, and wherein the side surfaces of the cover plate extend over the height of the loop portion, whereby the cover plate partially embraces the loop portion of the tubular heating body along the at least major length thereof.

2. The heating device according to claim 1, wherein the side surfaces include one longitudinal flange respectively, which flanges are angled towards each other such that the cover plate embraces the loop portion of the tubular heating body more than 180° while leaving a gap between the flanges .

3. The heating device according to claim 1 or 2, wherein side surfaces of the cover plate are substantially perpendicular to the main surface of the cover plate.

4. The heating device according to any of the claims 1 - 3, wherein the cover plate closely fits over the loop portion and follows the geometry of the loop portion.

5. The heating device according to claim 4, wherein, in suitable positions, the main surface has bent portions and the side surfaces have cuts.

6. The heating device according to any of the claims 1 - 5, wherein the loop portion has the form of at least one U-shaped loop.

7. The heating device according to claims 6, wherein a fastener is affixed to the cover plate, wherein the fastener comprises a clip having two end portions, which end portions are arranged to hold two opposed leg portions of the at least one U-shaped loop.

8. The heating device according to any of the claims 1 - 7, wherein the cover plate is made of stainless steel .

9. The heating device according to any of the claims 1 - 7, wherein the tubular heating body comprises an electric resistor heater element and wherein the tubular heating body, at the two ends thereof, is provided with one electrical connection terminal respectively for power supply of the electric resistor heater element

10. A laundry washing machine, comprising at least one heating device according to any of the claims 1 - 9.

11. The laundry washing machine according to claim

10, further comprising an inner tub for receiving laundry and an outer tub for holding a washing liquid, wherein the inner tub is rotatably supported in the outer tub, and wherein the heating device is removably arranged between the inner tub and the outer tub at the bottom of the outer tub.

12. The laundry washing machine according to claim

11, wherein the outer tub is provided with a securing device for preventing the heating device to contact the outer tub.

13. The laundry washing machine according to claim

12, wherein the securing device includes a casing for receiving a distal, not covered end of the loop portion, such that the cover plate and the casing together covers the entire length of the loop portion.

14. The laundry washing machine according to claim

13, wherein the securing device includes a corrugated plate, which in cooperation with the bottom of the outer tub, forms several casings for receiving the distal end of several heating devices respectively.

15. The laundry washing machine according to any of the claims 11 - 14, wherein the heating device is arranged at the bottom of the outer tub such that washing liquid, when circulating pass the loop portion, is able to directly contact the tubular heating body.