U.S. patent application number 10/510428 was filed with the patent office on 2005-05-19 for ballast weight for washing machines.
Invention is credited to Kaulbersch, Otto, Kreuziger, Ute, Wirthwein, Udo.
Application Number | 20050103062 10/510428 |
Document ID | / |
Family ID | 28051170 |
Filed Date | 2005-05-19 |
United States Patent
Application |
20050103062 |
Kind Code |
A1 |
Wirthwein, Udo ; et
al. |
May 19, 2005 |
Ballast weight for washing machines
Abstract
A washing machine includes parts that are mounted in a manner
that permits them to oscillate, particularly washing machine tubs,
on which ballast bodies are fixed. The ballast body is
approximately shaped like a ring or ring segment with a selectable
cross-sectional thickness and comprises, on at least one circular
are, a number of recesses and/or openings whose surfaces on points
of contact are complementary to corresponding outer contours of
fixing elements on the part. The ballast body is preferably made of
plastic and ferrous material, which is shaped by injection molding
a thermoplastic material, which contains significant proportions of
filling material consisting of hematite and./or magnetite, in order
to form a ballast body having a density >2.4 g/cm.sup.3.
Inventors: |
Wirthwein, Udo; (Creglingen,
DE) ; Kaulbersch, Otto; (Creglingen, DE) ;
Kreuziger, Ute; (Berlin, DE) |
Correspondence
Address: |
COHEN, PONTANI, LIEBERMAN & PAVANE
551 FIFTH AVENUE
SUITE 1210
NEW YORK
NY
10176
US
|
Family ID: |
28051170 |
Appl. No.: |
10/510428 |
Filed: |
January 7, 2005 |
PCT Filed: |
April 3, 2003 |
PCT NO: |
PCT/DE03/01221 |
Current U.S.
Class: |
68/19 ; 68/23R;
68/23.1; 68/23.3; 68/23.4 |
Current CPC
Class: |
D06F 37/262 20130101;
D06F 37/265 20130101 |
Class at
Publication: |
068/019 ;
068/023.00R; 068/023.1; 068/023.3; 068/023.4 |
International
Class: |
D06F 037/24 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2002 |
DE |
102 15 254.3 |
Claims
1-11. (canceled)
12. A washing machine comprising: a washing tub supported with
freedom to oscillate, the tub having a front loading opening
surrounded by an end surface; a plurality of fastening elements
upstanding from said end surface, said fastening elements having
external contours; and a ballast weight comprising a circular ring
section received against said end surface, said section having
openings with internal contours which are complementary to the
external contours of the fastening elements.
13. A washing machine as in claim 12 wherein the fastening elements
and the internal contours of the ballast weight consist essentially
of a thermoplastic material.
14. A washing machine as in claim 12 wherein the fastening elements
have, in a plane parallel to the end surface, one of a honeycomb
structure and a closed external surface with internal stiffening
ribs stiffening webs.
15. A washing machine as in claim 12 wherein the openings are one
of oval and kidney shaped.
16. A washing machine as in claim 12 wherein at least some of the
fastening elements have posts which are not in contact with said
external contour, said posts having respective threaded bores.
17. A washing machine as in claim 12 wherein the ballast body rests
simultaneously against the external contours of a plurality of
fastening elements.
18. A washing machine as in claim 12 wherein said ballast body has
a density of >2.4 g/cm.sup.3, said ballast body being injection
molded of a thermoplastic material containing a ferrous filler
comprising at least one of hematite and magnetite.
19. A washing machine as in claim 18 wherein said ballast body has
a density of 2.5 to 3.9 g/cm.sup.3.
20. A washing machine as in claim 19 wherein said ballast body has
a density of 2.9 to 3.5 g/cm.sup.3.
21. A washing machine as in claim 18 wherein said ballast body
comprises at least one of polyethylene and polypropylene.
22. A washing machine as in claim 18 wherein said ferrous material
constitutes 35-70% by volume of said ferrous material, said ferrous
material further comprising rolling scale.
23. A washing machine as in claim 17 wherein said thermoplastic
material forms the entire surface of said ballast body.
24. A ballast body for a washing machine, said ballast body having
a density of >2.4 g/cm.sup.3, said ballast body being injection
molded of a thermoplastic material containing a ferrous filler
comprising at least one of hematite and magnetite.
25. A ballast body as in claim 24 wherein said ballast body has a
density of 2.5 to 3.9 g/cm.sup.3.
26. A ballast body as in claim 25 wherein said ballast body has a
density of 2.9 to 3.5 g/cm.sup.3.
27. A ballast body as in claim 24 wherein said ballast body
comprises at least one of polyethylene and polypropylene.
28. A ballast body as in claim 24 wherein said ferrous material
constitutes 35-70% by volume of said ferrous material, said ferrous
material further comprising rolling scale.
29. A ballast body as in claim 24 wherein said thermoplastic
material forms the entire surface of said ballast body.
Description
[0001] The invention pertains to washing machines with components
which are mounted with the freedom to oscillate, especially washing
tubs, to which ballast bodies are attached, and also to ballast
bodies for this purpose.
[0002] Because plastic washing tubs are very light in weight, they
are not heavy enough to ensure the proper operation of the washing
machine in washing machines with modern oscillating systems. For
this reason, the washing tubs are weighted with ballast
weights.
[0003] EP 0 825 29.1 A1 describes a disk-shaped, approximately
circular weight, which is attached to the bottom of the washing
tub. The weight is made of an unspecified mixture of materials,
presumably concrete, with a density of >2 g/cm.sup.3. It rests
on three contact surfaces on a plane parallel to the main plane of
the bottom and is held by brackets, which are spaced equal
distances apart around a circle and which extend in a direction
perpendicular to the main plane. They are kept tightly pressed
against the narrow edge of the weight by a tensioning strap, which
encircles them externally.
[0004] A concrete weight which serves as a loading weight and which
is attached to the washing tub by a tensioning strap is also
described in DE 32 17 160 A1. In this case, an outer metal tire is
cast into the loading weight.
[0005] These types of tensioning rings around concrete parts suffer
from several disadvantages. Thin concrete breaks easily, especially
in the environment present here with wide temperature variations;
and under the otherwise clean conditions in which "white goods" are
manufactured, concrete weights also represent a contamination of
the production line.
[0006] The dimensional accuracy of weights of this type and of
their fastening points to washing tubs is not very high, nor is
there much freedom in designing them. Tensioning straps are
difficult to work with during the course of repairs, and their
functional reliability cannot always be guaranteed. It is difficult
to automate the fabrication of these ballast weights and the work
of fastening them to the tubs.
[0007] Loading weights of heavy, nonmetallic concrete with openings
which are complementary to frustum-shaped screw tubes attached to
the bottom of the washing tub are known from DE 42 38 686 C1 and DE
42 38 685 A1. Screws introduced from the surface of the loading
weight pull spring plates far into the openings on one side, and on
the other side they also pull the screw tubes, made of
thermoplastic material, into the openings from the bottom.
According to the recommendation in the former EP document, the
tension should be great enough that, in spite of the relaxation
natural to thermoplastic material, sufficient tensioning force will
still be present even at the end of the unit's service life. Aside
from the difficulty of applying the precise tightening torques
required in these difficult-to-access areas, the selected
thermoplastic apparently cannot be made homogeneous enough in
practice to meet the requirements imposed on these types of screw
joints in washing machines.
[0008] For other reasons, DE 38 34 112 A1 proposes that the upper
part of the plastic tub be made hollow and that it be provided with
an opening, through which a pourable bulk material, preferably
scrap iron of a sand-like or coarsely granular consistency, can be
added. These mass particles are first coated in a separate process
with a heat-insulating plastic layer, which is intended to provide
a layer of insulation against the walls of the tub, so that this
weight-equalizing mass will not remove any heat from the washing
liquor.
[0009] A process for producing a washing machine ballast weight
which consists of a hollow body of plastic, which is filled with a
special, heavy, inert material, is known from EP 0 812 946 A2. The
hollow body is designed as a ring-shaped ballast element, the shape
of which conforms to that of the washing tub. The method by which
the weight is attached to the tub is not disclosed.
[0010] A similar system is described in EP 0 969 134 A1, where the
counterweight, namely, a hollow body filled with concrete, has
openings for screws, which fasten the ring-shaped ballast weight to
the washing tub.
[0011] EP 0 798 412 A2 also describes a concrete-filled body with
openings, into which a partly nonpositive, partly positive
connector similar to an expansion anchor can be inserted. Screws
can be screwed into these anchors to fasten the ballast weight to
the washing machine.
[0012] EP 0 307 282 B1 describes a ballast weight for the end
surfaces of a washing machine tub with a washing drum which rotates
around a horizontal axis. This weight consists of concrete or an
agglomerate, especially a metal-plastic agglomerate, and has a
convex surface at least on the external side. On the internal side
facing the tub, surfaces are provided which are complementary in
form to that of the corresponding end surface of the tub, thus
making it possible for the weight to be attached stably to tub.
[0013] These are individual weights, which are attached segment by
segment to the tub and which therefore cannot be easily balanced
either with respect to each other or with respect to the tub.
Although a metal-plastic agglomerate is mentioned, it is impossible
to identify the materials out of which the agglomerate should be
made or the form which it should take.
[0014] Finally, a washing machine with components for attaching
weighting bodies and the weighting bodies themselves are known from
EP 0 417 460 A2. These weights are made out of reaction resin
concrete (concrete polymer) containing thermosetting materials. It
is also mentioned that the weight of the component can be increased
by the incorporation of denser additives such as iron scrap. Thus
various densities, that is, various weights, can be produced for
different applications. The production times and costs of
components such as this are high when they are mass produced,
because temperature-dependent pot lives and final curing times must
be taken into account.
[0015] Proceeding from this state of the art, the invention is
based on the problem of designing a ballast weight as a rigid,
fracture-resistant molded part in the shape of a ring, which can be
easily attached to a washing tub; on the problem of producing these
types of molded parts easily in a separate operation while ensuring
at the same time that they have a long service life; and on the
problem of overcoming the disadvantages, known from the state of
the art, of thermoplastic materials.
[0016] These problems are solved according to the invention by the
features of claims 1 and 7. Elaborations of the invention are
addressed in the subclaims.
[0017] For washing machines with components which are supported
with the freedom to oscillate, especially washing tubs, to which
ballast bodies, preferably those containing a certain amount of
plastic and a certain amount of ferrous material, are attached, the
solution provides, first, that the ballast body has approximately
the shape of a ring or of a section of a circular ring of optional
cross-sectional thickness, and that, in at least one circular arc,
several openings and/or holes are provided, the surfaces of which
are complementary to the corresponding external contours of
fastening elements on the component. The fastening elements on the
component and the surface of the ballast body should consist
essentially of thermoplastic material and should, in a plane
more-or-less parallel to the surface of the ballast body, have a
honeycomb structure or a closed outside contour with stiffening
webs in between.
[0018] As a result, the ballast body can rest simultaneously
against the outside contours of a plurality of fastening elements,
which minimizes the load exerted by the ballast bodies on the
component. This measure is especially effective when the outside
contours are oval or kidney-shaped. As a result, the ballast body
can rest simultaneously against the outside contours of a plurality
of fastening elements, which minimizes the load exerted by the
ballast bodies on the component. Other shapes are also possible,
however, for the external contours or for the rib structure of the
fastening elements in particular, as long as the principle of the
invention is still followed.
[0019] The inventors conducted a large number of studies and
calculations based on the finite-element method and found that some
of the openings will always be in engagement with the fastening
elements of, for example, the appropriately designed front section
of a washing tub. That is, the creep behavior typical of
thermoplastics such as polyethylene or of the preferred
polypropylene as seen in the creep test at temperatures typical for
washing machines under both static and dynamic loads has hardly any
disadvantageous effect. The fastening structures, when of the
ribbed type, are designed with an appropriate safety factor
sufficient to prevent fatigue fractures. Because the screw joints
for fastening the ballast body are operative here in addition to
the external contours of the fastening element, there is a higher
degree of security in comparison with the state of the art with
respect to the correct, permanent seating of the ballast body. In
addition, some of the fastening elements are selected to serve only
as guides for the ballast body.
[0020] According to additional aspects of the solution, a ballast
body for washing machines, especially a ballast body to be fastened
to washing tubs, is produced by injection molding from a mixture of
plastic material and ferrous material and has a density of >2.4
g/cm.sup.3. It consists, namely, of a thermoplastic filled with a
significant amount of hematite and/or magnetite.
[0021] After the plastication of the thermoplastic in an extruder,
a metal component, preferably a pure ore of hematite or magnetite
or mixtures of the two with the smallest possible grain size, i.e.,
small enough not to interfere with the extrusion or
injection-molding process, is then added to the extruder before the
extrusion or injection-molding or press-molding. In view of the
fact that the ballast bodies have relatively large cross sections,
even quite granular metal components can be used. Experiments have
shown that rolling scale, which contains certain amounts of FeO and
impurities in addition to Fe.sub.2O.sub.3 and Fe.sub.3O.sub.4, can
also be used, but the pure ores are preferred.
[0022] Whereas thermoplastics have a specific gravity or density of
0.9-1.0 g/cm.sup.3, hematite and magnetite have a density of
approximately 5.2-5.3 g/cm.sup.3. They, too, like pure washed ores,
are easy to handle and do not generate any dust and therefore can
be used directly in the injection-molding or extrusion process. The
metal components are completely surrounded by the thermoplastic
material, so that, according to this method, a completely
homogeneous body with a plastic surface is obtained. To achieve a
specific gravity or density of >2.4 g/cm.sup.3, the hematite
portion or the magnetite portion or the mixture of the two should
make up 35-70% of the volume of the body, which leads to a specific
gravity which, according to the experiments conducted by the
inventors, should be in the range of 2.5-3.9 g/cm.sup.3, and
preferably 2.9-3.5 g/cm.sup.3. In terms of the amount of added
metal component, this is a compromise to ensure good processability
in, for example, an extruder with an appropriate die, which has
been custom-made to suit the dimensions of the ballast body.
[0023] The invention is to be described in greater detail below on
the basis of a diagrammatic illustration of an exemplary
embodiment:
[0024] FIG. 1 shows an overall view of a model of a washing tub and
a ballast weight;
[0025] FIG. 2 shows the contour of a washing tub according to FIG.
1;
[0026] FIG. 3 shows the contour of a ballast weight according to
FIG. 1; and
[0027] FIG. 4 shows a cross section of a ballast weight seated on a
fastening element of the washing tub according to FIG. 1.
[0028] A washing tub 2 of a front-loading washing machine with a
front-loading opening 21 is equipped with a ballast weight 1, which
extends around this front opening. So that the weight and the
adjacent components of the washing machine can be balanced, the
weight 1 has various recesses 15. From the top surface, the weight
can be connected to the washing tub 2 by the use of appropriate
openings 13.
[0029] FIG. 2 shows a perspective view of a washing tub similar to
that of FIG. 1, except that the weight 1 has been removed. A row of
fastening elements 23, 24 is arranged around the front-loading
opening 21 on the end surface 22 of the washing tub 2. The
fastening elements 23 are also equipped with posts 233, into which
connectors passing through the weight can be inserted. In this
case, a total of eight fastening elements is shown, including four
fastening elements 23 with means for accepting connectors and four
fastening elements 24 without means for accepting connectors for
the attachment of the weight 1.
[0030] It is not necessary to use eight fastening elements in all
cases. A different number of fastening elements 23, 24 can be used
to deal with different load situations created by the ballast
weight 1 and/or by the centrifugal speed of the washing machine
and/or by other loads. The kidney-shaped or oval fastening elements
shown here could also be replaced by round or polygonal
elements.
[0031] The external contours 232, 242 of the fastening elements 23,
24 both lie on circles, that is, on an outer circle closer to the
outside surface of the washing tub and on an inner circle closer to
the front-loading opening 21. As a result, the ballast weight 1
exerts its load uniformly on the tub. The principle of the
invention is that the openings or holes in the ballast weight are
complementary to the external contours, and that the surfaces of
these openings or holes rest filly against the external contours
232 as a result of which most of the load is applied to the
external contours 232 of the fastening elements. A necessary
positive connection between the ballast weight 1 and the washing
tub 2 can then be distributed over a few threaded posts 233.
[0032] It is easy to see the ribbed or honeycomb structure of the
fastening elements. A calculation of the force vectors has shown
that a structure of this type ensures optimal conditions for the
transmission of the observed torques and loads without causing any
difficulties with respect to the injection-molding process.
[0033] The washing tub is preferably made of a plastic such as
polyethylene or polypropylene, so that both the washing tub and the
loading weight, which is shown by itself in FIG. 3, preferably have
similar surfaces.
[0034] FIG. 3 shows the bottom surface of the ballast weight
according to FIG. 1, i.e., the side facing the washing tub.
[0035] In contrast to the washing tub, the recesses in the ballast
weight are of different shapes. Common to all the recesses 11, 11',
11" is that their surface 111, which serves as a contact surface
for the external contours 232 of the fastening elements, are all of
the same design in order to ensure the most homogeneous possible
contact with the external contours 232, 242 of the fastening
elements 23, 24. Depending on how many fastening elements 23, 24
with corresponding external contours 232, 242 are present, the same
number of recesses 11, 11', 11" will be provided in the ballast
weight 1. As already mentioned, the ballast weight has recesses 15
in consideration of the center of gravity of the washing tub and of
the loading weight and in consideration of other components of the
washing machine. To compensate for the weight in the area of the
recesses 15 shown in FIG. 3, it is provided that the loading weight
also has elevations 14 inside the recesses, which can fit into the
empty spaces in the fastening elements 23, 24 and thus increase the
local weight of the ballast.
[0036] FIG. 4 shows a cross section through the ballast weight of
FIG. 1 in the area of a fastening element 23 with a threaded post
233. The weight 1, as already shown in FIG. 1, has an upper
depression 12, 13 to allow a fastening means to be inserted into
the threaded post 233. The weight 1 rests on the surface 22 of the
washing tub 2, next to the front-loading opening 21, but the
surfaces 111 of the weight are also in contact with the external
contours 232, 242 of the fastening elements 23, 24. The honeycomb
or ribbed structures 241 of the fastening elements are especially
easy to see here. In the case of fastening element 24, these
structures provide the external contour 242 with appropriate
support, whereas the structures 231 provide the external contour
232 with similar support.
[0037] As previously described, the weight also has elevations 14
in some of the fastening elements 23. These elevations are used to
adjust the position of the center of gravity. Although they fit
into the fastening elements 23, they do not make contact with them,
just as the threaded posts 233 do not make contact with the
weight.
* * * * *