EP2377986A2

EP2377986A2 - Laundry treating appliance with force damping feet

Info

Publication number: EP2377986A2
Application number: EP11155872A
Authority: EP
Inventors: Donald R Miller; Brenner M Sharp
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 2010-04-13
Filing date: 2011-02-24
Publication date: 2011-10-19
Also published as: EP2377985A2; US20110247374A1; EP2377985A3; EP2377986A3; BRPI1101319A2

Abstract

A laundry treating appliance having a cabinet, a rotatable drum, and at least one foot extending from and supporting the cabinet, with the foot being configured to dampen the vibrations of the laundry treating appliance.

Description

A laundry treating appliance may be used to treat laundry according to a predetermined cycle of operation. In one implementation, a laundry treating appliance may include a drum defining a treating chamber and mounted for rotation inside a cabinet. The drum of the laundry treating appliance may generate vibrations during rotation, especially when the laundry creates an imbalance within the drum, which may be caused by unevenly distributed laundry inside the drum.
Feet are provided on the cabinet to provide for leveling the cabinet relative to the surface on which the cabinet rests. The feet provide a path for the vibrations to pass from the laundry treating appliance to the surface. A foot is normally placed at each corner of the cabinet.
In one aspect, the invention, relates to a laundry treating appliance having a cabinet; a rotatable drum that may be suspended within the interior defining the laundry treating chamber; a first pair of relatively non-compliant feet extending from the cabinet and supporting the cabinet on the floor; and a second pair of relatively compliant feet extending from the cabinet and supporting the cabinet on the floor.
The invention will be further described by way of example with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of a laundry treating appliance in the form of a laundry washing machine according to a first embodiment of the invention.
Figure 2 is a bottom partial perspective view of the laundry treating appliance of Figure 1.
Figure 3 is a front perspective view of the laundry treating appliance of Figure 1 and illustrating an alternative position showing one possible motion of the laundry treating appliance in response to the vibrations generated from an out-of-balance condition during the operation of the laundry treating appliance having laundry inside the drum.
Figure 4 is a front view of a representative foot of Figure 1.
Figure 5 is front view of a first pair of relatively non-compliant feet of Figure 1 according to one embodiment of the invention.
Figure 6 is a front view of a second pair of relatively compliant feet of Figure 1 according to one embodiment of the invention
Figure 7 is a plot of the acceleration forces in g's versus spin speed of the laundry treating appliance incorporating the feet of Figures 5 and 6, with a comparison of a laundry treating appliance with two pairs of non-compliant feet.
Figure 8 is a schematic view of a laundry treating appliance according to a second embodiment of the invention.
Figure 1 is a perspective view of a laundry treating appliance 10 according to a first embodiment of the invention. As illustrated, the laundry treating appliance 10 may be a vertical axis laundry washing machine 12, although the laundry treating appliance 10 may be other machines, non-limiting examples of which include a horizontal axis laundry washing machine, a laundry dryer, a fabric freshener, and a non-aqueous laundry system.
As used herein, the "vertical axis" washing machine refers to a laundry washing machine having a rotatable drum that rotates about a generally vertical axis relative to a surface that supports the washing machine. However, the rotational axis need not be perfectly vertical to the surface. The drum may rotate about an axis inclined relative to the vertical axis, with fifteen degrees of inclination being one example of the inclination. Similar to the vertical axis laundry washing machine, the horizontal axis washing machine refers to a washing machine having a rotatable drum that rotates about a generally horizontal axis relative to a surface that supports the washing machine. The drum may rotate about the axis inclined relative to the horizontal axis, with fifteen degrees of inclination being one example of the inclination. The washing machine described herein may share many features of a traditional automatic laundry washing machine, which will not be described in detail except as necessary for a complete understanding of the invention.
As illustrated, the laundry treating appliance 10 in the form of a vertical axis washing machine 12 may include a cabinet 14, a door 16, a first pair of relatively non-compliant feet 18, a second pair of relatively compliant feet 20, a suspension system 22, and a user interface 24. The cabinet 14 may define an interior 26 and may include a top wall 28, a front wall 30, a pair of side walls 32, and a rear wall 34. A chassis 38 or frame may be provided on which the various walls may be mounted to define four corners of the machine 40. The front wall 30 may help define a front 29 of the laundry treating appliance 10. The front 29 is the side where a user may be typically positioned to operate the laundry treating appliance 10. The rear wall 34 may help define a back 35 of the laundry treating appliance 10. The back 33 is the side where tubing for a water inlet and a drain (not shown) are located. The door 16 may be hingedly mounted to the top wall 28 and may be configured to be selectively movable to provide access to the interior 26.
A tub 35 may be located within the interior 26 and a rotatable drum 36 may be mounted within and rotatable relative to the tub 35. The suspension system 22 may operably couple the tub 35 and the cabinet 14 such that some of the vibrations generated from the rotatable drum 36 are dampened. The drum 36 may define a treating chamber 42 for receiving laundry items to be treated. The drum 36 may include a plurality of perforations (not shown), such that liquid may flow between the tub 35 and the drum 36 through the perforations.
An agitator 43 may be mounted within and rotatable relative to and/or with the drum 36. The agitator 43 may have a lower circular base or skirt portion 44, a central shaft 45 extending upwardly from the base 44, and at least one vane or blade 48 spaced around and extending radially from the central shaft 45. The central shaft 45 may be operably coupled with a bottom 46 of the drum 36. A variety of other designs for the agitator 43 may also be used without affecting the scope of the invention. The drum 36 and/or the agitator 43 may be driven by an electrical motor 47 operably connected to the drum 36 and/or the agitator 43.
The user interface 24 may include a parameter selector 54 that may be one or more knobs, switches, displays, and the like, which a user may select to operate the laundry treating appliance 10. A controller 56 may be operably coupled with the parameter selector 54 to selectively operate a pre-determined cycle of operations set by the user through the parameter selector 54.
The first pair of relatively non-compliant feet 18 and the second pair of relatively compliant feet 20 may be extended from the cabinet 14 to support the cabinet 14 on a floor 50. Figure 2 illustrates that a first pair of corners 58 may be located near the front 60 of the cabinet 14 and that a second pair of corners 62 may be located near the back 64 of the cabinet 14. The first pair of relatively non-compliant feet 18 and the second pair of relatively compliant feet 20 may be coupled with the first pair of corners 58 and the second pair of corners 62 of the cabinet 14 respectively. That is, the first pair of relatively non-compliant feet 18 may be extended from the first pair of corners 58 and the second pair of relatively compliant feet 20 may be extended from the second pair of corners 62 to support the cabinet 14 on the floor 50.
Figure 3 illustrates the laundry treating appliance of Figure 1 and as well as an alternative position (shown in phantom) showing one possible motion of the laundry treating appliance in response to the vibrations generated from an out-of-balance condition during an operation of the laundry treating appliance, such as during a spin or extraction phase of the cycle of operation, having laundry inside the drum.
In a typical cycle of operation, multiple fabric items 68, which collectively form a laundry load, are placed in the drum 36. Some of the fabric items 68 will be in direct contact with the agitator 43 and some will not. A washing fluid 66 may also be introduced into the drum 36. As the agitator 43 moves, the individual fabric items 68 will be moved directly or indirectly by the agitator 43 to impart mechanical energy to the items, which will move the fabric items 68 about the treating chamber 42. More specifically, during a pre-programmed cycle of operation, the central shaft 45 inside drum 36 may continuously oscillate about its own vertical axis in clockwise and counterclockwise directions for a pre-determined time to impart mechanical energy to the laundry 68 to wash out soil and stain on the laundry 68.
During the cycle of operation, the laundry 68 may become unevenly distributed within the drum 36 and may pile up in some regions inside the drum 36. Particularly, in the spinning phase where the drum 36 is being rotated at very high speeds, the effect of an unevenly distributed load may be noticeable, and may generate severe vibrations. The unevenly distributed load may cause an out of balanced condition so great that the drum 36 may bottom out its suspension and/or contact a portion of the cabinet 14, which may be very undesirable as the severe vibrations may from time to time make a loud noise.
The out-of balanced load or unevenly distributed load in the drum 36 may generate an oscillating force in the form of vibrations, which act on the cabinet 14, the first and the second pairs of feet 18 and 20 (Figure 2), and ultimately the floor 50. If the magnitude of the oscillating force is great enough, the cabinet 14 may pivot about a pivot line 70 in the laundry treating appliance 10. This may result in a side-to-side rocking motion as illustrated in phantom in Figure 3. The higher the rotational speed of the drum 36 inside the cabinet 14, the greater the magnitude of the oscillating force may result. Thus, the higher rotational speed of the drum 36 results is an increased likelihood that the laundry treating appliance 10 will begin a side-to-side rocking motion. The cabinet vibrations (A) may be measured using an accelerometer that may be attached to the upper part of the laundry treating appliance 10 while the drum 36 rotates at a pre-determined spin speed for a pre-determined time, and may be represented by g's of acceleration.
Both the first pair of relatively non-compliant feet 18 and the second pair of relatively compliant feet 20 may include a representative foot 72 as illustrated in Figure 4. As illustrated, the foot 72 may comprise a stem 74 and a pad 76. The stem 74 may be coupled with the cabinet 14 by connecting members 78. The pad 76 may be operably coupled with the stem 74 to support the cabinet 14 on the floor 50. The connecting members 78 may include at least one of a washer 80 and a nut 82. The stem 74 may be threaded such that when it is coupled with one of the mating connecting members 78 the levelness and the height of the laundry treating appliance 10 may be adjusted relative to the floor 50 on which the laundry treating appliance 10 is positioned.
When the laundry treating appliance 10 weighing M (Kg) is supported by N number of feet extending from the corners of the cabinet 14, a weight-per-foot-normalized stiffness NK (1/mm) of each foot comprising material with a stiffness K (N/mm) may be represented according to equation (1): $NK (1 / mm) = \frac{K (N / mm)}{\frac{M (Kg) \times g (m / s^{2})}{N}}$
The acceleration due to gravity g (m/s²) in equation (1) is defined to be 9.807 m/². The stiffness K (N/mm) is an inherent mechanical property of the foot that measures the resistance offered by an elastic body to any deformation such as bending, stretching or compression. The physical meaning of the weight-per-foot-normalized stiffness NK (1/mm) is the reciprocal of the amount of deformation that each foot would experience if the total weight M (Kg) of the laundry treating appliance 10 is supported by the foot. For instance, the weight-per-foot-normalized stiffness of 0.2 (1/mm) may be construed to mean that one foot may deform by 5 mm if one foot supports the entire weight of the laundry treating appliance 10. In case the laundry treating appliance 10 has four feet on which the weight of laundry treating appliance 10 is evenly distributed, the foot may deflect by 1.25 mm. Therefore, the weight-per-foot-normalized stiffness would be the value that is normalized with respect to the weight and the number of feet of the laundry treating appliance 10.
The pad 76 may be formed of a resilient material such as rubber, polymer, or a rubber-polymer composite. Further, the pad 76 may be made of two or more resilient materials in the form of a stacked or a randomly mixed composite. Depending on the weight-per-foot-normalized foot stiffness required for the foot 72, materials other than a resilient material may be used for pad 76.
Figure 5 illustrates the first pair of relatively non-compliant feet 18 including non-compliant feet 84. The first pair of relatively non-compliant feet 18 may be defined as feet having a weigh-per-foot-normalized stiffness value greater than or equal to 1.04 (1/mm). More specifically, the relatively non-compliant feet 84 may be defined as feet having the weight-per-foot-normalized stiffness values ranging from 1.04 to 1.56 (1/mm). Figure 5 includes arrows 85; the length of the arrow 85 represents the magnitude of the deformation of non-compliant feet 84 in the vertical direction.
It should be noted that for purposes of this description, while the weight-per-foot-normalized stiffness values are being described in terms relative to the second decimal place, that this should not be construed as indicating that there is substantive relevance at the second decimal place. For purposes of the invention, the range of 1.04 to 1.56 (1/mm) could be rounded to the range 1.0 to 1.60 without impacting the practical results of the range. The similar is true of the other values in this description.
Figure 6 illustrates the second pair of relatively compliant feet 20 including compliant feet 86. The second pair of relatively compliant feet 20 may be defined as feet having a weight-per-foot-normalized stiffness value less than or equal to 0.71 (1/mm). More specifically, the relatively compliant feet 86 may be defined as feet having the weight-per-foot-normalized stiffness values ranging from 0.16 to 0.71 (1/mm), with a round range of 0.10 to 0.70. Figure 6 includes arrows 87; the length of the arrow 87 represents the magnitude of the deformation of the compliant feet 86 in the vertical direction. Thus, as illustrated, the magnitude of the deformation in the vertical direction for the non-compliant foot 84 is smaller than the vertical deformation for the compliant foot 86. The first pair of relatively non-compliant feet 18 located near front 60 of the cabinet 14 may have a weight-per-foot-normalized stiffness at least 2.0 times greater than the weight-per-foot-normalized stiffness of the second pair of relatively compliant feet 20 located near back 64 of the cabinet 14. This may effectively suppress the vibrations and possible corresponding side-to-side rocking movement of the laundry treating appliance 10.
In operation, when oscillating forces in the form of the vibrations are ultimately transferred to the stem 74 and the pad 76 of each of the first pair of relatively non-compliant feet 18 and the second pair of relatively compliant feet 20, the second pair of relatively compliant feet 20 located near the back 64 of the cabinet 14 may isolate the laundry treating appliance 10 from the floor 50 to suppress the vibrations during high speed spinning phase (for example, above 700 rpm). At the same time, the first pair of relatively non-compliant feet 18 located near the front 60 of the cabinet 14 may control the side-to-side rocking movement of the laundry treating appliance 10 during any intermediate rinse spins speeds (for example, 350-550 rpm).
Figure 7 is a plot of the acceleration forces in g's versus spin speed of the laundry treating appliance 10 incorporating the first pair of relatively non-compliant feet 18 and the second pair of relatively compliant feet 20 during a spinning cycle in the laundry treating appliance 10. Further, a comparison of a laundry treating appliance with two pairs of non-compliant feet is also presented for comparison purposes. In the plot, the spin speed (i.e., the x-axis) may be the spin speed of the drum during a water extraction phase. The g's of acceleration (i.e., the y-axis) may be the amount of the vibration in the side-to-side rocking motion (such as that shown in phantom in Figure 3).
In the graph, it is shown that the g's of acceleration for the laundry treating appliance 10 having the first pair of relatively non-compliant feet and the second pair of relatively compliant feet is substantially suppressed compared to the laundry treating appliance having two first pairs of relatively non-compliant feet at a full spin speed region (approximately > 700 rpm). The g's of acceleration for the laundry treating appliance 10 having the first pair and the second pair of feet at the intermediate spin phase range was further suppressed by adapting a newly proposed intermediate spin speed around 400 rpm, instead of using a previous intermediate spin speed of 450 rpm. Figure 7 clearly illustrates that the first pair of relatively non-compliant feet near the front of the cabinet and the second pair of relatively compliant feet near the back of the cabinet may significantly suppress the vibrations and the side-to-side rocking movements.
Figure 8 is a schematic view of a laundry treating appliance 90 according to a second embodiment of the invention. While the first embodiment was described in terms of compliant feet, the embodiment of Figure 8 illustrates that this concept may be thought of in terms as the feet having a damping system that provides the compliance.
As illustrated in Figure 8, first and second pairs of feet 94, 96 extend from a cabinet 92 of an appliance 90. Each of the first and second pairs of feet 94, 96 comprise a first and second damping systems 95, 97, respectively, on which are provided pads 99.
The feet 94, 96 may have different degrees of damping, which may be quantified by a damping coefficient and a spring coefficient, to achieve the desired functionality. Therefore, the feet are illustrated as a damper and spring supporting the pad 99 to the cabinet 92. More specifically, each foot 94 of the first damping system 95 may include a first damper 100 having a damping coefficient C_f and a first spring 102 having a stiffness K_f, where the first damper 100 and the first spring 102 may be arranged in parallel to each other. The first pair of feet 94 may be provided along a front side 104 of the laundry treating appliance 90 at opposite corners of the cabinet 92. Likewise, each foot 96 of the second damping system 97 may include a second damper 106 having a damping coefficient C_r and a second spring 108 having a stiffness K_r, where the second damper 106 and the second spring 108 may be arranged in parallel to each other. The second pair of feet 96 may be provided along a rear side 110 of the laundry treating appliance 90 at opposite corners of the cabinet 92.
In order to provide the desired stiffness to effectively suppress the vibrations from the laundry treating appliance 90 to the floor 98, the relationship of the damping coefficients C_f and C_r (N·sec/mm) of the dampers 100, 106 and the stiffnesses K_f and K_r (N/mm) of the springs 102, 108 may be expressed as follows: $\frac{C_{f}}{C_{r}} = \sqrt{\frac{K_{f}}{K_{r}}}$
The second embodiment of the invention may be thought of as a broader or more generalized form of the first embodiment of the invention, in which the non-compliant and compliant feet of the first embodiment are modeled as the first and second damping systems, respectively. As such, the first dampening system may have similar properties as those disclosed above the non-compliant feet and the second dampening system may have similar properties as those disclosed above for the compliant feet.
It is noted that other configurations in terms of the number, location of damping systems are possible. For example, instead of having pairs of feet forming the first and second dampening systems, the dampening systems may be formed by single elongated feet that extend, partially or fully, along opposite sides of the cabinet 92 of the laundry treating appliance 90. In such a configuration, the relationship of the dampening coefficients and stiffnesses of each dampening system may follow equation (2).
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. For example, the number of relatively non-compliant feet may not be two, non-limiting examples may include one, three, or any number. Similarly the number of relatively compliant feet may vary. Reasonable variation and modification are possible within the scope of the invention which is defined in the appended claims.

PARTS LIST

10: laundry treating appliance
12: washing machine
14: cabinet
16: door
18: first pair of relatively non-compliant feet
20: second pair of relatively compliant feet
22: suspension system
24: user interface
26: interior
28: top wall
29: front
30: front wall
32: side wall
33: back
34: rear wall
35: tub
36: drum
38: chassis
40: corner
42: laundry treating chamber
43: agitator
44: base
45: central shaft
46: bottom
47: motor

48: blade
50: floor
54: parameter selector
56: controller
58: first pair of corners
62: second pair of corners
66: washing fluid
68: laundry
70: pivot line
72: foot
74: stem
76: pad
78: connecting member
80: washer
82: nut
84: non-compliant foot
85: magnitude of the deformation of the non-compliant feet
86: compliant foot
87: magnitude of deformation of the compliant feet
90: laundry treating appliance
92: cabinet
94: first pair of feet
95: first damping system
96: second pair of feet
97: second damping system
98: floor
99: pad
100: first damper
102: first spring
104: front side
106: second damper
108: second spring
110: rear side
A: cabinet vibrations

C_f: damping coefficient of first damper
C_r: damping coefficient of second damper
K_f: stiffness of first spring
K_r: stiffness of second springt

Claims

A laundry treating appliance comprising:
a cabinet defining an interior;

a rotatable drum suspended within the interior defining a laundry treating chamber;

at least one relatively non-compliant foot extending from the cabinet and supporting the cabinet on the floor;

at least one relatively compliant foot extending from the cabinet and supporting the cabinet on the floor;

wherein the at least one relatively non-compliant foot has a weight-per-foot-normalized stiffness at least about 2.0 times greater than the stiffness of the relatively compliant feet.
The laundry treating appliance according to claim 1 wherein the cabinet defines a front portion and a rear portion and the at least one relatively non-compliant foot is located at the front portion of the cabinet and the at least one relatively compliant foot is located at the rear portion of the cabinet.
The laundry treating appliance according to claim 1 wherein the at least one relatively non-compliant foot comprises a first pair of relatively non-compliant feet and the at least one relatively compliant foot comprises a second pair of relatively compliant feet.
The laundry treating appliance according to claim 3 wherein the cabinet defines a front portion and a rear portion and the first pair of feet are located at the front portion of the cabinet and the second pair of feet are located at the rear portion of the cabinet.
The laundry treating appliance according to claim 4 wherein the cabinet further defines four corners, with a first pair of the corners located at the front portion and a second pair of the corners located at the rear portion, and the first pair of feet being mounted to the first pair of corners and the second pair of feet being mounted to the second pair of corners.
The laundry treating appliance according to any one of the preceding claims wherein each foot comprises a resilient pad having a predetermined stiffness.
The laundry treating appliance according to any one of the preceding claims wherein the cabinet comprises a frame and the feet are mounted to the frame.
The laundry treating appliance according to any one of the preceding claims wherein at least one of the feet comprises a damping system providing the corresponding stiffness.
The laundry treating appliance according to claim 8 wherein the damping system comprises a damper and a spring.
The laundry treating appliance according to claim 8 or 9 wherein the at least one of the feet comprises a pad coupled to the cabinet by the damping system.