WO2017182936A1

WO2017182936A1 - Household appliance with an electric component of electromagnetic radiation

Info

Publication number: WO2017182936A1
Application number: PCT/IB2017/052198
Authority: WO
Inventors: Simon BREZOVNIK
Original assignee: Gorenje Gospodinjski Aparati, D.D.
Priority date: 2016-04-20
Filing date: 2017-04-18
Publication date: 2017-10-26
Also published as: SI25187A

Abstract

A household appliance including at least one electric component that produces electromagnetic radiation, and at least one structural element with such material- geometrical properties that make it move in response to electromagnetic radiation, especially in a frequency of electromagnetic radiation, wherein a shielding element is arranged between said electric component, which is a source of electromagnetic radiation, and said structural element.

Description

Household appliance with an electric component of electromagnetic radiation

The present invention relates to a household appliance including at least one electric component that produces electromagnetic radiation, preferably a built-in oven with at least one fan and an AC motor.

Household appliances are known to include electric components that, when in use, produce and emit relatively powerful electromagnetic radiation into the environment. Such components are for instance transformers and AC motors. These components may be used in household appliances as stand-alone units or as constituent parts of vital components of a household appliance, such as a built-in oven fan driven by an AC motor. Moreover, it is known that the intensity of electromagnetic radiation (hereinafter EM radiation) depends in a certain spatial point on transmission intensity of the source or source power and a distance from the source. The longer the distance from the source, the more rapid the reduction in the density of electromagnetic radiation. If a metallic element having such material-geometric properties that make it responsive to EM radiation is located in an area of increased density of EM radiation, i. e. close to the source, undesired oscillations of this metallic element may occur resulting in the production of undesired vibrations and noise that propagate in the environment. This is especially the case when an electric component producing EM radiation is arranged close to an external wall of an appliance due to spatial design- conditioned requirements, and this wall is made of a metallic material such as a ferromagnetic material with a relatively large surface and relatively small thickness. This poses huge problems in those devices, particularly household appliances, where low vibrations and the related noise are rather disturbing, for instance in built-in ovens.

The currently known solutions tackle to reduce the influence of EM radiation on vibrations of adjacent metallic structural elements, particularly ferromagnetic elements, by placing EM radiation sources, such as electric motors or transformers, sufficiently far away from such structural elements or by geometrically shaping and fastening them to adjacent elements in a way to reduce their responsivity to the excitation frequency of EM radiation. This may be achieved for instance on walls of a housing by indentations into a surface, with which stiffness is modified/increased and the range of own frequencies transferred outside of the excitation frequency of EM radiation; further by increasing the thickness of the basic material of a wall, etc. However, such measures have their limits particularly when household appliances are in question due to spatial requirements, since reduction in the active operating space is not desired, and also due to economic requirements which do not allow any increase in the production cost.

The task of the invention is to eliminate the above-identified drawbacks, particularly to prevent or at least considerably reduce propagation of EM radiation emitted by electric components integrated in a household appliance to adjacent structural elements, thus preventing vibrations of these structural elements, wherein the solution should be simple and preserve the basic structure of a household appliance unmodified while meeting all safety requirements. The solution must also comply with economical requirements.

The technical problem is solved by the invention, the main characteristic of which lies in the fact that a metallic shielding element is arranged between an electric component which is a source of EM radiation and a structural element possessing such material- geometrical properties to be responsive to EM radiation.

A metallic shielding element is a structural element whose material-geometrical properties prevent propagation of EM radiation by drain or absorption, by transformation to heat and/or by reflection. The shielding element can be made from a metallic material, particularly a magnetic material such as a ferromagnetic material. The shielding element is arranged between an electric component that is a source of EM radiation and a structural element, wherein it is particularly favourable if a distance from the electric component is smaller than the distance from the structural element in order to cover the greatest portion of EM radiation possible. The metallic shielding element can be fastened to an electric component which is the source of EM radiation. The shielding element should have such geometry and be fastened in such a way that the element is stiff enough not to respond to EM radiation by oscillation that would propagate into the environment with a disturbing noise. The stiffness can be achieved by design, for instance a sheet metal with indentations, perforated sheet metal, by an adequate ratio between the main dimensions of a surface/surfaces and the thickness of the sheet metal.

Importantly, the shielding element has such shape and is arranged in a way to considerably prevent propagation of EM radiation in at least one direction, i. e. in a direction, in which the propagation of EM radiation has the greatest impact on adjacent structural elements, for instance in a direction from the source towards the closest wall of the housing. Here, the shielding element is arranged in one plane lying between the source of EM radiation and the closest wall of the housing. It is even more favourable for the shielding element to be arranged in several planes that intersect or are parallel to each other in order to prevent propagation of EM radiation in several directions from the source, i. e. the source of EM radiation is predominantly covered. It is even more favourable if the shielding element is arranged in a laminar manner, for instance in the shape of a continuous plate, a plate with openings in the form of slots, holes, said openings being arranged all over the place, or in the shape of a lamella-like or grid-like plate. A further advantage of a shielding element in the form of a plate with openings is air circulation, for instance for cooling an electric component during its operation. Here, not only EM radiation is limited; the geometry of the element which redirects radiation and transforms air molecules into heat and kinetic energy partly contributes to suppression of noise produced by the electric component. The shielding element may be fastened to an electric component that causes EM radiation by known fastening elements such as pins, screws, rivets etc.

If the shielding element is fastened to a structural element inside a household appliance, the fastening should allow the metallic shielding element to move. Damping elements for vibration damping are favourably arranged in fastening connections, such as rubber parts, parts from thermoplastic elastomers, fabrics, etc.

Due to usual requirements for a minimal distance required between an electric component that generates increased EM radiation and a structural element, such as a wall of a housing of a household appliance, the impact of EM radiation on a wall of a housing is considerably increased. An increased distance between a structural element, i. e. a wall of a housing of a household appliance, and a source of EM radiation, which would considerably reduce vibrations, is usually not possible without simultaneously reducing the applicable space of a household appliance and by increasing the outer dimension of a household appliance.

The invention will be described in more detail by way of embodiments. It goes without saying that a person skilled in the art can find solutions in other fields on the basis of being acquainted with the present invention without circumventing the essence of the invention.

A household appliance, a built-in oven in this embodiment, includes a housing, in which an oven compartment intended for thermal treatment of food is arranged. The oven compartment is defined by a casing and a door that closes the front opening of the oven compartment. An electric motor of a fan is arranged within the built-in oven in a known way between the housing and a rear wall of the casing of the oven compartment. The rear wall of the casing of the oven compartment is provided with a through hole, through which a shaft of the electric motor of the fan projects into the oven compartment. The fan propeller is mounted on the shaft and covered by a cover. A cooling fan is arranged directly adjacent to the electric motor fan on the shaft for cooling the electric motor. There is a minimal distance between the electric motor of the fan or its housing and the rear wall of the housing of the built-in oven, said distance not being smaller than the required minimal safety distance. While the fan is operating to achieve forced air convection during a cooking procedure in said oven, EM radiation is propagating from the AC motor of the fan. To eliminate oscillations/vibrations of the rear wall of the housing made from a ferromagnetic material and responsive to EM radiation, a shielding element of the invention is arranged between the rear wall of the housing and the electric motor of the fan. The shielding element is formed as a plate with equally sized and equidistantly arranged holes. The size of the shielding plate-like element is identical to or larger than the perpendicular projection of external dimensions of the electric motor of the fan onto the rear wall of the housing of a household appliance. The shielding element is fastened directly to the housing of the electric motor of the fan by fastening elements in the form of screws.

In a second embodiment, the shielding element is a component part of an electric motor assembly. A plate-like shielding element having a size that is substantially identical to or larger than the projection of the electric motor onto the shielding element is fastened to the electric motor assembly by fastening elements of a known type. Such ready-made assembly of an electric motor and a shielding element is installable into a household appliance or any other appliance/device, in which vibration problems occur due to EM radiation of built-in electric components.

Claims

1. A household appliance including at least one electric component that produces electromagnetic radiation, and at least one structural element with such material- geometrical properties that make it move in response to electromagnetic radiation, especially in a frequency of electromagnetic radiation, characterized in that a shielding element is arranged between said electric component, which is a source of electromagnetic radiation, and said structural element, said shielding element preventing propagation of electromagnetic radiation.

2. The household appliance according to claim 1, characterized in that the size of the shielding element is substantially identical to or larger than the perpendicular projection of external dimensions of the electric component onto the rear wall of the housing of a household appliance.

3. The household appliance according to claim 2, characterized in that the shielding element is arranged in at least one plane.

4. The household appliance according to claim 3, characterized in that the shielding element is arranged in several planes that intersect or a parallel to each other.

5. The household appliance according to claim 3, characterized in that the shielding element is conceived as a plate.

6. The household appliance according to claim 5, characterized in that the shielding element includes openings.

7. The household appliance according to claim 6, characterized in that the openings are in the shape of slots and/or holes equidistantly arranged all over the shielding element.

8. The household appliance according to any preceding claim, characterized in that the shielding element is fastened to an electric component producing electromagnetic radiation.

9. The household appliance according to any preceding claim, characterized in that the shielding element is fastened to a structural element in the interior of the household appliance via flexible connection that allows the shielding element to move.

10. The household appliance according to any preceding claim, characterized in that the shielding element is fastened to a structural element in the interior of the household appliance via damping element.

11. The household appliance according to any preceding claim, characterized in that the shielding element is made from a metallic material.

12. The household appliance according to claim 11, characterized in that the shielding material is made from a magnetic material.

13. The household appliance according to any preceding claim, characterized in that the household appliance is a built-in oven.

14. A household appliance comprising at least one electric component that produces electromagnetic radiation, and at least one structural element with such material- geometrical properties that make it move in response to electromagnetic radiation, especially in a frequency of electromagnetic radiation, characterized in that the electric component is provided with a shielding element.