Note: Descriptions are shown in the official language in which they were submitted.
CA 02444320 2003-10-06
TITLE: DISHWASHER DOOR BALANCING SYSTEM
BACKGROUND OF THE II~IENTION
This invention relates to household appliances, including, but not limited to
dishwashers. More specifically, this invention relates to a s~~stem for
balancing the door of
the household appliance.
In household or kitchen appliances, such as dishwashers, it is desirable to
have
proper door balance. When there is proper door balance, the door can open in a
smooth,
controlled motion. It is desirable for an operator to open the door to the
desired level with
no sudden fall of the door or tendency for the door to spring back up from an
open position.
Manufacturers have attempted to provide proper door balance by manually
adjusting the
'balance of dishwasher doors.
Adjustment of a dishwasher door is a burden to dishwasher manufacturers. Based
on different model features (such as, but not limited to the control type, the
presence of
sound dampers, the material weight, or other variations) the weight of the
dishwasher doors
will vary. Therefore, in order to provide for proper balancing, each door
assembly requires
a specific counterbalance force to provide proper adjustment. If there is
improper
adjustment, a front-loading door can fall hard to a noisy and abrupt stop in
the horizontal
position, or the door may not sit horizontal without the operator having to
physically push
the door down to the fully open position. Thus, improper adjustment is a
nuisance to the
consumer. In particular, improper adjustment of a dishwasher door is believed
to result in
a poor quality perception by consumers of the dishwasher.
In dishwashers, a set of extension springs are typically used for providing
proper
door balance. Then, each extension spring can be manually adjusted for each
dishwasher
model in order to provide for proper balancing. One problem is that this
adjustment
process is labor-intensive, and thus can be cost prohibitive.
Another attempt is a system wherein a stranded rope runs through a groove in a
fixed plastic part to generate friction for restricting door motion. One
problem with such
an approach is that the stranded rope can wear and break during normal use due
to the wear
resulting from friction. A broken rope can result in a service call.
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Therefore, a primary object of the present invention is the provision of an
improved
household or kitchen appliance, such as a dishwasher.
A further object of the present invention is the provision of a dishwasher
door that
provides for proper adjustment without requiring a manual adjustment process.
A further object of the present invention is the provision of a dishwasher
having a
door balancing system that provides for smooth, controlled motion of the door.
Yet another object of the present invention is the provision of a dishwasher
door
balancing system that provides consumers with a high quality perception of the
dishwasher.
A further object of the present invention is the provision of a dishwasher
door
balancing system that allows for variance in the weight of the dishwasher
door.
Yet another object of the present invention is the provision of a dishwasher
door
balancing system that uses frictional force without causing undue wear on the
dishwasher.
These and/or other objects, features, or advantages of the present invention
will
become apparent from the specification and the claims that follow.
SUMMARY OF THE INVENTION
The present invention relates to a kitchen or household appliance having a
door,
such as, but not limited to a dishwasher. The present invention provides for
proper
balancing of a dishwasher door without requiring manual adjustment of springs
or other
manual adjustments to compensate for the weight of the particular dishwasher
door.
According to one embodiment of the present invention, a kitchen appliance
includes a base portion, a door hingably connected to the base portion, a cord
operatively
connected to the door, an extension spring operatively connected to the cord
and the base
portion to partially balance opening of the door by exerting a. force on the
cord and the
door, and a damping pulley is positioned along the cord between the extension
spring and
the door to further balance opening of the door by providing resistance to
motion of
opening the door without manual adjustment, The extension spring
counterbalances most
of the door weight. Then, to account fox variance in door weight for different
models, the
damping pulley system resists motion of the opened dishwasher doer. In the
damping
pulley system, friction is applied 'to resist rotation at the pulley. The
present invention
provides for applying the friction in various ways. Also, the ;pulley can
include teeth to
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prevent the slippage of the cord. For example, a flange in operative contact
with the
damping pulley can provide resistance to motion of opening the door. The
flange can be a
piece of spring steel that engages a perimeter surface of the damping pulley.
The flange
can engage a side-wall of the pulley to provide resistance to motion of
opening the door.
According to another aspect of the present invention., the present invention
provides
for a door balancing system for a dishwasher having a cabinet and a door. The
door
balancing system includes an extension spring operatively connected to the
cabinet; a cord
operatively connected to the extension spring and the door, and a pulley
engaging the cord
between the extension spring and the door such that the extension spring
provides a first
force to balance opening of the door and the pulley resists motion of opening
the door to
further balance opening of the door.
According to another aspect of the present invention, a front-loading
dishwasher is
provided. The front-loading dishwasher has a cabinet and a door operatively
connected to
the cabinet and includes an extension spring operatively corn~ected ro the
cabinet to provide
a force for partially counterbalancing weight of the door, a cord operatively
connected
between the extension spring and the door, a damping pulley positioned along
the cord to
provide resistance to motion of opening of the dishwasher door such that the
door opens in
a controlled manner without a manual adjustment to alter the force provided by
the
extension spring. The dishwasher can include a tlange in operative contact
with the
damping pulley to increase resistance to the motion of opening the door.
BRIEF DESCRIPTION OF THE DRA~JVINGS
Figure 1 is a perspective view of a dishwasher.
Figure 2 is a side view of the bottom portion of a dishwasher with the door
closed
and having a door balancing system with a toothed pulley according t~ one
embodiment of
the present invention.
Figure 2A is a view similar to Figure 2, except with the door open.
Figure 3 is a side view of a dishwasher door balancing system according to
another
embodiment of the present invention.
Figure 4 is a side view of a dishwasher door balancing system according to
another
embodiment of the present invention.
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Figure 5 is a side view of a dishwasher balancing system according to another
embodiment of the present invention.
Figure 6 is a front view of the pulley of the door balancing system taken
along lines
6-6 of Figure 5.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for balancing the weight of doors of a kitchen
or
household appliance such as a dishwasher. Figure i illustrates a dishwasher
10. The
dishwasher 10 includes a dishwasher door 12 and a dishwaslher base portion 14.
The
dishwasher door 12 is hingably connected to the dishwasher base portion 14,
such as along
a bottom portion of the dishwasher base portion 14. The dishwasher 10 shown is
a front-
loading dishwasher with the door 12 opening outwardly and downwardly.
Figure 2 provides a side view of the bottom portion of the dishwasher 10. In
Figure
2, the dishwasher door 12 is hingably connected to the dishwasher base portion
14 at the
1 S door hinge 16. A stranded rope, cable or other type of cord 18 is also
operatively
connected to the dishwasher door 12 in any convenient manner. For example, as
shown in
the drawings, the forward end of the cord 18 includes a bead or loop, which is
received in a
notch 32 of an inwardly extending arm 30 of the door 12. The rearward end of
the cord 18
is connected to an extension spring 26 that is connected to the dishwasher
base portion 14.
A pulley 20 is located between the extension spring 26 and the dishwasher door
12. The
cord 18 is in operative contact with the pulley 20. The pulley 20 rotates in
the direction
indicated by arrow 28. The pulley 20 can include a plurality of teeth 22 that
may be
molded into the pulley 20. The pulley 20 is pivotal about a pivot 36, which
can be a
shoulder bolt. The cord 18 can include catch members such as over molded beads
or
swaged ferrules 24 that matingly contact between the teeth 22 of the pulley
20. This
restricts the motion of the cord 18 in order to reduce or elimi,~ate slippage.
Other types of
catch members can be used so that the cord 18 can matingly contact with the
teeth 22 of the
pulley 20 in order to allow smooth opening of the dishwasher door 12.
The positioning of the cord 18 as shown allows the extensiorq spring 26 to
exert an
inwardly directed force on the cord 18 to provide resistance to the motion of
opening the
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dishwasher door 12. Figure 2A illustrates the dishwasher door 12 in an open
position with
the extension spring 26 expanded.
Figure 3 shows another embodiment of the present invention. In Figure 3, the
cord
18A is wrapped around the pulley 20. Wrapping the cord 18A completely around
an outer
S flange 27 of the pulley 20 reduces or eliminates slippage, since there are
no beads on the
cord 18A.
The damping system for the pulley 20 can be provided in different manners: For
example, in Figure 4, a steel spring flange 34 is in operative contact with
the pulley 20 in
order to exert a friction force on the perimeter edge 27 of the pulley 20. The
steel spring
flange 34 can be operatively connected to the dishwasher base portion 14 with
a support
member 38. The steel spring flange 34 provides friction such that the pulley
resists the
motion of opening the door to further balance opening of the door.
Another embodiment of the present invention is shown in Figures 5 and 6. In
Figures 5 and 6, a spider-like steel compression spring 44 is mounted behind
pulley 20 at
the pivot 36. The spring 44 has multiple legs 48, each having a substantially
flat flange 42
in operative contact with a flat surface 46 of the pulley 20. This contact
exerts a frictional
force on the pulley 20 to smooth the motion of opening the door. In Figure 6,
the pivot 36
consists of a shoulder bolt to pivotally connect the pulley to the dishwasher
tub support 40
of the dishwasher base portion 14. Although the present invention contemplates
other
manners of providing frictional force for providing balancing, preferably
friction is not
applied in a manner that will create undue wear and increase the need for
servicing.
Thus, a kitchen or household appliance, such as a dishwasher, has been
disclosed
that has an extension spring to baiance weight of the kitchen appliance door
and is adapted
for balancing without manual adjustment of the extension spring. The present
invention
contemplates that one or more extension springs andJor damping pulleys can be
used. For
example, the present invention contemplates that two sets of damping pulleys
and
extension sprzngs can be used on opposite sides of a dishwasher. The present
invention
also contemplates variations and equivalents in the manner in which the pulley
is
dampened. These and other variations and equivalents are within the spirit and
scope of
the present invention.
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