DOMESTIC APPLIANCE

Abstract

A household appliance includes a receiving region, and an insulating element attached to the receiving region and is set up to acoustically insulate the receiving region. The insulating element includes a foamed matrix material and particles embedded in the matrix material.

Claims

1-15. (canceled)

16. A household appliance, comprising: a receiving region; and an insulating element attached to the receiving region and is set up to acoustically insulate the receiving region, said insulating element including a foamed matrix material and particles embedded in the matrix material.

17. The household appliance of claim 16, constructed in a form of a water-guiding household appliance.

18. The household appliance of claim 16, wherein the insulating element at 40° C. and at a frequency of 100 to 800 Hz has a loss factor (VLF) of greater than 0.2, preferably of greater than 0.35, further preferably of greater than 0.5.

19. The household appliance of claim 16, wherein the insulating element has a thermal conductivity of between 20 and 80 mW/(m*K), preferably of between 40 and 60 mW/(m*K), further preferably of between 50 and 60 mW/(m*K).

20. The household appliance of claim 16, wherein the insulating element has a density of less than 300 kg/m.sup.3, preferably of less than 250 kg/m.sup.3, further preferably of less than 200 kg/m.sup.3.

21. The household appliance of claim 16, wherein the particles have a density which is greater than a density of the foamed matrix material.

22. The household appliance of claim 16, wherein the particles have a density of between 500 and 8000 kg/m.sup.3, in particular of 2200 kg/m.sup.3.

23. The household appliance of claim 16, wherein the particles have a density of 2200 kg/m.sup.3.

24. The household appliance of claim 16, wherein the particles are graphite particles.

25. The household appliance of claim 16, wherein the particles are expanded graphite particles.

26. The household appliance of claim 16, wherein the particles have intumescent properties.

27. The household appliance of claim 16, wherein the matrix material is a polyurethane.

28. The household appliance of claim 16, wherein the matrix material has viscoelastic properties.

29. The household appliance of claim 16, wherein the particles are arranged so as to be evenly distributed in the matrix material.

30. The household appliance of claim 16, wherein the insulating element is directly foamed onto the receiving region.

31. The household appliance of claim 16, wherein the particles have a modulus of elasticity which is greater than a modulus of elasticity of the matrix material.

32. The household appliance of claim 16, wherein the particles have a particle size ranging from 200 to 1500 μm.

33. The household appliance of claim 16, wherein the particles have a particle size smaller than 750 μm.

34. The household appliance of claim 16, wherein the particles have a particle size smaller than 500 μm.

35. The household appliance of claim 16, wherein the particles added to the matrix material and include particles which differ from one another in particle size, in shape, in material and/or in quantity thereof.

Description

[0043] FIG. 1 shows a schematic perspective view of an embodiment of a household appliance;

[0044] FIG. 2 shows a highly enlarged schematic sectional view of an embodiment of a receiving region of the household appliance according to FIG. 1;

[0045] FIG. 3 shows a highly schematic view of an embodiment of an insulating element for the receiving region according to FIG. 2;

[0046] FIG. 4 shows a diagram in which the loss factor of the insulating element according to FIG. 3 is plotted against the frequency;

[0047] FIG. 5 shows a further diagram in which the loss factor of the insulating element according to FIG. 3 is plotted against the frequency; and

[0048] FIG. 6 shows a further diagram in which the loss factor of the insulating element according to FIG. 3 is plotted against the frequency.

[0049] In the figures, elements which are the same or functionally the same are provided with the same reference characters unless specified otherwise.

[0050] FIG. 1 shows a schematic perspective view of an embodiment of a household appliance 1. The household appliance 1 is, in particular, a water-guiding household appliance, such as for example a household dishwasher or a household washing machine. The household appliance 1, however, may also be a refrigerator, a stove, an oven or the like. Hereinafter, however, it is assumed that the household appliance 1 is a household dishwasher.

[0051] The household appliance 1 has a receiving region 2 which is able to be closed by a door 3, in particular in a water-tight manner. To this end, a sealing device may be provided between the door 3 and the receiving region 2. The receiving region 2 is preferably cuboidal. The receiving region 2 may be a washing container. The receiving region 2 may be arranged in a housing of the household appliance 1. The receiving region 2 and the door 3 may form a washing chamber 4 for washing items to be washed.

[0052] The door 3 is shown in FIG. 1 in the open position thereof. The door 3 may be closed or opened by pivoting about a pivot axis 5 provided at a lower end of the door 3. A loading opening 6 of the receiving region 2 may be closed or opened by means of the door 3. The receiving region 2 has a bottom 7, a ceiling 8 arranged opposite the bottom 7, a rear wall 9 arranged opposite the closed door 3 and two side walls 10, 11 arranged opposite one another. The bottom 7, the ceiling 8, the rear wall 9 and the side walls 10, 11 may be produced, for example, from a stainless steel sheet. The bottom 7 may be produced alternatively from a plastic material, for example.

[0053] The household appliance 1 also has at least one receptacle for items to be washed 12 to 14. Preferably, a plurality of receptacles for items to be washed 12 to 14, for example three thereof, may be provided, wherein the receptacle for items to be washed 12 may be a lower receptacle for items to be washed or a lower basket, the receptacle for items to be washed 13 may be an upper receptacle for items to be washed or an upper basket, and the receptacle for items to be washed 14 may be a cutlery drawer. As FIG. 1 also shows, the receptacles for items to be washed 12 to 14 are arranged one above the other in the receiving region 2. Each receptacle for items to be washed 12 to 14 is able to be displaced selectively into or out of the receiving region 2. In particular, each receptacle for items to be washed 12 to 14 is able to be pushed or moved in a push-in direction E (arrow) into the receiving region 2 and pulled or moved out of the receiving region 2 in a pull-out direction A (arrow) counter to the push-in direction E (arrow).

[0054] FIG. 2 shows a highly enlarged schematic sectional view of an embodiment of the receiving region 2. In particular, only a detail of the side wall 11 is shown in FIG. 2. The side wall 11 may be produced, as mentioned above, for example, from a stainless steel sheet. The side wall 11 comprises an inner face 15 facing the washing chamber 4 and an outer face 16 facing away from the washing chamber 4. The inner face 15 and the outer face 16 are positioned parallel to one another. The side wall 11 has a thickness d11. The thickness d11 may be, for example, 0.2 to 1 mm.

[0055] The household appliance 1 comprises an insulating element 17 which is attached to the receiving region 2 for the acoustic insulation of the receiving region 2, or acoustically insulating said receiving region. The insulating element 17 may also be denoted as an insulation element. The insulating element 17 may encase the receiving region 2. In other words, the insulating element 17 may be provided on the bottom 7, on the ceiling 8, on the rear wall 9, on the side walls 10, 11 and/or on the door 3. Alternatively, the insulating element 17 may also be provided, for example, only on the side walls 10, 11 or only on the side walls 10, 11 and on the rear wall 9. A plurality of insulating elements 17 may be provided. For example, in each case such an insulating element 17 may be assigned to each side wall 10, 11.

[0056] The insulating element 17 is provided on the outer face on the receiving region 2 facing away from the washing chamber 4. In particular, as FIG. 2 shows, the insulating element 17 is attached to the outer face 16 of the side wall 11. The insulating element 17 may be fused or adhesively bonded to the outer face 16, for example. The insulating element 17 may also be positioned only on the outer face 16. The insulating element 17 has a thickness d17 of preferably more than 2 mm, further preferably of more than 10 mm, further preferably of more than 15 mm. Thus the thickness d17 is preferably greater than the thickness d11 by a multiple thereof.

[0057] The insulating element 17 comprises a foamed matrix material 18 in which particles 19 are embedded. “Foamed” in the present case means that a plurality of cells or pores 20 are enclosed in the matrix material 18. The pores 20 may be filled, for example, with air. The pores 20 may have any geometry. For example, the pores 20 are spherical or ellipsoidal. The matrix material 18 and the pores 20 form together a polyurethane foam 21 (PUR foam). A polyurethane may be manufactured by a mixture consisting of a plurality of basic components, namely an isocyanate and a polyol. Moreover, the mixture may also contain a propellant. The isocyanate and the polyol are in each case liquids. If the propellant is present in the mixture of the isocyanate and the polyol, which leads to a degassing during the reaction of the isocyanate with the polyol, the matrix material 18 is foamed during the course of the chemical reaction, whereby the pores 20 are produced in the matrix material 18 and the polyurethane foam 21 is formed.

[0058] The pores 20 are preferably closed. In other words, the pores 20 are not connected together. The pores 20, however, may also be open or open-pored. In this case, the pores 20 are connected together. The matrix material 18 and thus the polyurethane foam 21 may be provided with very different material properties. The material properties substantially depend on the chemical ingredients of the basic components. Preferably, the polyurethane foam 21 has viscoelastic properties. “Viscoelasticity” in the present case is denoted as a partially elastic and partially viscous material behavior. Viscoelastic materials, therefore, combine all of the features of solids and liquids therein.

[0059] The polyurethane foam 21 or the insulating element 17 has a thermal conductivity of between 20 and 80 mW/(m*K), preferably of between 40 and 60 mW/(m*K), further preferably of between 50 and 60 mW/(m*K). The polyurethane foam 21 may have a density of less than 300 kg/m.sup.3, preferably of less than 250 kg/m.sup.3, further preferably of less than 200 kg/m.sup.3.

[0060] The insulating element 17 is preferably directly foamed onto the receiving region 2, in particular onto the side wall 11. To this end, chemical additives, which prevent the insulating element 17 from being released from the receiving region 2, may be admixed into the matrix material 18. Moreover, the outer face 16 of the side wall 11 may be alternatively or additionally pretreated, for example roughened, such that the connection between the insulating element 17 and the side wall 11 is not able to be released. Alternatively, the insulating element 17 may also be adhesively bonded onto the receiving region 2, fused thereon or even simply positioned thereon.

[0061] By the application of the insulating element 17 over the entire surface of the receiving region 2, an effective acoustic insulation of the receiving region 2 is ensured. An advantage of completely foaming around the receiving region 2 with the insulating element 17 is that gaps which are present may be sealed without spaces, whereby an improved acoustic insulation is further ensured.

[0062] The particles 19 are arranged so as to be evenly distributed in the matrix material 18. Moreover, the particles 19 may function as nucleation sites for the pores 20. The particles 19 are preferably mixed into the basic components of the matrix material 18 to be mixed. For example metal, stone or other inorganic materials are relevant as particles 19. Organic materials, such as for example plastic, are also relevant if the density and the modulus of elasticity of the particles 19 is greater than that of the matrix material 18.

[0063] Particularly preferably, the particles 19 are graphite particles, in particular expanded graphite particles. The use of expanded graphite particles has the advantage that in this case the particles 19 have intumescent properties. “Intumescence” in the present case is to be understood as an expansion or swelling, i.e. an increase in the volume of the particles 19 by the action of heat, without a chemical conversion thereof. In other words, the matrix material 18 may decompose by the action of heat on the insulating element 17, whilst the particles 19 configured as expanded graphite particles expand or swell and thus form a carbon foam functioning as a heat brake on or adjacent to the receiving region 2.

[0064] As mentioned above, the particles 19 have a greater density than the polyurethane foam 21 and than the matrix material 18. The particles 19 may have a density of between 500 and 8000 kg/m.sup.3, in particular of 2200 kg/m.sup.3. As mentioned above, the modulus of elasticity of the particles 19 is also greater than the modulus of elasticity of the matrix material 18. The particles 19 preferably have a particle size which is smaller than 500 μm. The particles 19 are present as powder and, due to the size thereof, are sufficiently small to be evenly distributed in the matrix material 18. The size of the particles 19 is substantially smaller than 500 μm. In other words, particles 19 which are larger than 500 μm are also permitted, but it is advantageous if 60% of the particles 19 are smaller than 500 μm. Preferably 80%, in particular 90%, of the particles 19 are smaller than 500 μm. By mixing the particles 19 into the matrix material 18, the pore structure of the polyurethane foam 21 changes. In other words, this means the size, the number and/or the geometry of the pores 20 in the insulating element 17.

[0065] For manufacturing the insulating element 17, the particles 19 are added to one or more of the liquid basic components of the matrix material 18 and evenly distributed in the mixture of the basic components. It is also possible to add the particles 19 to the already mixed basic components whilst they are still liquid. Moreover, different types of particles 19 may be combined from different substances. These particles 19 may also have differences in their size distribution and physical properties. If particles 19 which are similar or even different in terms of size, type and quantity are added, a large range of differently optimized insulating elements 17 may be manufactured with the same basic components. This may be used in order to manufacture insulating elements 17 for different applications on a production line.

[0066] The insulating element has at 40° C. and at a frequency of 100 to 800 Hz a loss factor of greater than 0.2, preferably of greater than 0.35, further preferably of greater than 0.5. The “loss factor” in the present case, with different types of physical vibrations, is to be understood as the relationship between the imaginary part, which is subject to loss, and the loss-free real part of a complex variable. The loss factor of the insulating element 17 may be influenced by adding the particles 19 to the matrix material 18. Advantageously, this relationship may be used if the loss factor is thereby increased over the entire frequency and temperature range or if an increase is also possible in the frequency and temperature range relevant for the individual case.

[0067] FIG. 3 shows a highly schematic view of the insulating element 17. The insulating element 17 comprises a plurality of mass points or masses m which are formed by the particles 19. Thus the particles 19 result in masses m in the polyurethane foam 21. The matrix material 18 with the pores 20, i.e. the polyurethane foam 21, forms spring stiffnesses s and damping members d. The insulating element 17 is thus shown as a spring-mass oscillator. The particles 19 significantly differ in the density thereof from the density of the filling gas of the pores 20 and ideally, but not necessarily, from the density of the matrix material 18. In other words, the density of the particles 19 is greater than the density of the matrix material 18 without the particles 19. This leads to a change in the structure of the mass distribution in comparison with a foam material without particles 19.

[0068] Moreover, as mentioned above, it is advantageous if the modulus of elasticity of the particles 19 is greater than the modulus of elasticity of the polyurethane foam 21 and also greater than the modulus of elasticity of the unfoamed matrix material 18. As a result, the matrix material 18 acts as a spring/damper element and the particles 19 act merely as masses m. The stiffness or the spring action of the particles 19 may be ignored in this case. This leads to an advantageous use of the properties of the damping members d in the insulating element 17 and thus to an increase in the loss factor.

[0069] If different resonance frequencies of the spring-mass oscillators are generated by the different masses m of the particles 19 and the variable spring stiffnesses s between the particles 19, a broad resonance peak may be generated. Within this resonance peak, the loss factor is increased by the efficient use of the damping members d. The viscous properties of the polyurethane foam 21 and the formation thereof as viscoelastic foam are advantageously used. Thus either the loss factor may be increased as a whole or improved in the relevant frequency and temperature range.

[0070] FIGS. 4 to 6 show in each case a diagram in which the loss factor VLF is plotted against the frequency F. In this case the solid line represents an insulating element, not shown, without particles 19 and the dashed line represents the above-described insulating element 17 with the particles 19. FIGS. 4 to 6 differ from one another by the variable output level of the loss factor VLF. According to FIG. 4, the output level of the loss factor VLF is 0.2. According to FIG. 5 the output level of the loss factor VLF is 0.4. According to FIG. 6 the output level of the loss factor VLF is 0.6. In other words, the increase in the loss factor VLF may start from any output level.

[0071] As may be clearly derived from FIGS. 4 to 6, the loss factor VLF in the insulating element 17 increases significantly relative to the insulating element without particles 19, not shown. Adding the particles 19 into the matrix material 18 changes the loss factor VLF. In particular, the loss factor VLF is increased.

[0072] An increase in the loss factor VLF by up to 30%, in particular by at least 20%, may be achieved. The loss factor VLF may be adapted and optimized to the application, i.e. to the actual frequency and temperature range, by the addition of the particles 19, for example by means of different materials, particle sizes or the like. The increased loss factor VLF leads to a reduced radiation of sound power. By controlling the quantity and type of the added particles 19, the loss factor VLF may be influenced over a wide range by one and the same matrix material 18.

[0073] Whilst the present invention has been described by way of exemplary embodiments, it may be modified in many different ways.

REFERENCE CHARACTERS USED

[0074] 1 Household appliance [0075] 2 Receiving region [0076] 3 Door [0077] 4 Washing chamber [0078] 5 Pivot axis [0079] 6 Loading opening [0080] 7 Bottom [0081] 8 Ceiling [0082] 9 Rear wall [0083] 10 Side wall [0084] 11 Side wall [0085] 12 Receptacle for items to be washed [0086] 13 Receptacle for items to be washed [0087] 14 Receptacle for items to be washed [0088] 15 Inner face [0089] 16 Outer face [0090] 17 Insulating element [0091] 18 Matrix material [0092] 19 Particle [0093] 20 Pore [0094] 21 Polyurethane foam [0095] A Pull-out direction (arrow) [0096] d Damping member [0097] d11 Thickness [0098] d17 Thickness [0099] E Push-in direction (arrow) [0100] F Frequency [0101] m Mass [0102] s Spring stiffness [0103] VLF Loss factor