Patent Grant
7793525
1. Field of the Invention
The invention relates generally to an agitator assembly for a washing machine and more particularly to an agitator assembly comprising an agitator with vanes that can flex in multiple directions.
2. Description of the Related Art
Automatic washing machines are widely known and commonly used to wash a load of clothes comprising one or more clothing articles in accordance with a programmed wash cycle. Clothes washers of this type typically comprise a perforated basket located within an imperforate tub, with the basket being rotatable relative to the tub. The clothing is placed in the basket where the wash liquid is free to flow between the basket and the tub through the perforations. Vertical axis immersion-type washing machines typically comprise a single- or dual-action agitator assembly within the basket, and the agitator assembly rotates relative to the basket about a vertical axis to impart mechanical energy to the submerged clothing. Single-action agitator assemblies comprise a reciprocating agitator having an agitator barrel and a skirt portion with circumferentially spaced vanes. The agitator vanes extend radially outward from the agitator barrel, and the lower edge thereof can be completely integral with the skirt or spaced from the skirt. The agitator vanes, along with the agitator barrel and the skirt, are typically injection molded polypropylene. Consequently, the vanes are relatively stiff and are substantially inflexible when they are integral with the skirt or flex only about an axis parallel with the vertical axis when the lower edge is spaced from the skirt.
Dual-action agitators incorporate an auger for driving the clothes down to the agitator. A traditional auger surrounds the agitator barrel and is coupled to the agitator by a unidirectional clutch. The auger typically comprises a tubular body and a continuous helical vane having a constant cross section. The helical vane is integral with and extends outwardly from the body and comprises a root portion where it meets the body and tapers outward to a tip. The helical vane can be perpendicular to the central axis of the body or, more preferably for better wash performance, undercut or inclined relative to the central axis, as shown in the above mentioned Pinkowski patent. Augers are preferably produced with an injection molding process. To accommodate the undercut of the helical vane, the injection molding process uses multiple radially-moveable mold sections surrounding a core, wherein after the material is injected into the core and sufficiently solidified, the molds are retracted radially while the core is simultaneously axially pulled from the molds.
The combination of the method of making the auger and the physical characteristics (continuous spiral, undercut vane, and constant radial cross section) creates a limit on the radial extent or width (the radial distance from the tubular body to the tip) of the helical vane and causes the helical vane to have a relatively thick root. The actual width of the vane is limited to a value less than the maximum vane width, which is the largest possible width for the vane. The thickness of the vane at the root and the maximum vane width depends on the degree of vane taper, which also referred to as the draft angle, from the root to the tip. The draft angle is a function of the undercut angle, which is the angle between the lower surface of the vane and the outer wall of the body, and the vane pitch, which is the distance between adjacent turns of the vane and is indicative of the slope of the vane. Assuming all other variables are constant, a larger undercut angle and a smaller pitch each individually corresponds to a smaller draft angle and, thus, a thinner root and a larger maximum vane width. However, the combination of a desired undercut angle and pitch to achieve a desired auger performance in prior art auger designs results in a relatively large draft angle and, thus, a thick root and a shorter width. As an example, some prior art auger vanes have a root that are on the order of 12-16 mm and a maximum vane width of about 33-35 mm. Corresponding ratios of vane width to root thickness for these values range from about 2.2-2.8, which means that the vane width is less than about 3 times the root thickness.
Unfortunately, a thick root can lead to several problems associated with the injection molding process and with the auger itself. For example, not only do such vanes require a large volume of material, but also the root must sufficiently solidify before the auger can be removed from the molds. As a result, the cycle times can be undesirably long, and the life of the mold is relatively short. Additionally, when the root is thick, the cylindrical body warps into an oblong, egg-like shape, and a depression or sink forms on the inside wall of the body at the vane because the root of the vane tends to pull the body outward while cooling. Because the auger fits over and rotates relative to the agitator barrel, the auger must be adapted to accommodate for warpage and sinks so that it is concentric with the agitator barrel.
To avoid the problems associated with thick roots, the undercut angle can be increased, and the pitch can be decreased to thereby decrease the root thickness. Such a solution would also increase the maximum vane width, which can increase the effectiveness of the auger. However, the undercut angle and the pitch are selected based at least partly upon the washing performance and efficiency of the washing machine, and it is undesirable to change the undercut angle and the pitch to the extent needed to achieve a large maximum vane width and a relatively thin root.
During use of the washing machine, the auger vane imparts a downward motion to the clothing articles and the wash liquid, and the agitator vanes impart a centrifugal motion to the clothing articles and the wash liquid. Hence, as the auger rotates in one direction and the agitator rotates reciprocally, the auger pushes the clothing articles from the surface of the wash liquid down towards the agitator, and the agitator pushes the clothing articles outward toward the basket. As the clothing articles approach the inner wall of the basket, the basket functions as a barrier to further centrifugal outward movement, and centrifugal pressure from the moving wash liquid and from other clothing articles is converted to higher static pressure. Increased static pressure pushes the wash liquid and clothing articles, and some wash liquid and clothing articles move downward while the majority moves upward along the basket towards the surface of the wash liquid where they are pushed downward again by the auger. As a result, the clothing articles are washed as they move along a toroidal path, and one full cycle along this path is commonly referred to as a rollover.
Because the agitator relies on the interactions between the wash liquid, the clothing articles, and the basket to move the clothing articles upward, the agitator has to impart a large amount of mechanical energy to the clothing articles to maintain the movement thereof along the toroidal path and to achieve a desired number of rollovers. Friction losses during flow transmission from the outward movement to the upward movement require additional energy to transform flow from outward direction to upward direction. A motor drives reciprocal rotation of the agitator, and the rotational energy of the agitator is converted to the mechanical energy applied to the clothing articles. Larger mechanical energy requirements, therefore, can strain the motor and result in high electrical energy consumption. Additionally, clothing articles can collect at the bottom of the basket and impede movement of the clothes load along the toroidal path, which can lead to reduced washing performance and effectiveness of the washing machine.
A washing machine according to one embodiment of the invention comprises a basket defining a wash chamber and a clothes mover mounted in the wash chamber. The clothes mover comprises a body mounted for reciprocal rotational movement about a generally vertical axis and at least one vane. The at least one vane comprises a base mounted to the body and a tail extending from the base and having an upper edge that transitions into a tip, the tail being free of the body for side-to-side flexing and configured such that a portion of the tail extending between the upper edge and the tip can flex from a generally vertical position toward the body.
The tail can further comprise a strengthening region having a thickness greater than the rest of the tail. The strengthening region can extend in a direction defined between the base and the tip. The thickness of the strengthening region can increases toward the base.
A height of the tail can increase from the base of the at least one vane to the tip of the tail.
The tip can extend radially beyond the body.
The body can comprise a depression that at least partially receives the tail and accommodates the side-to-side flexing of the tail.
The body can be made of a first material, and at least the tail of the at least one vane can be made of a second material different from the first material. The entire vane can be made of the second material. The second material can be more flexible than the first material. The second material can comprise an elastomer. The first material can comprise polypropylene. The at least one vane can be integrally molded with the body.
The clothes mover can be an agitator.
The clothes mover can comprise a plurality of the vanes. The plurality of the vanes can be equally spaced. The vanes can be oriented radially relative to the vertical axis.
A washing machine according to another embodiment of the invention comprises a basket defining a wash chamber and a clothes mover located in the wash chamber. The clothes mover comprises a body made of a first material and at least one vane mounted to the body made of a second material different from the first material.
A flexural modulus of the second material can be greater than a flexural modulus of the first material. The second material can comprise an elastomer. The first material can comprise polypropylene.
The at least one vane can be integrally molded with body.
The at least one vane can extend radially beyond the body.
The at least one vane can comprise a base and a tail that is free of the body for flexing in a first direction. The first direction can be side-to-side. The at least one vane can be configured to flex in a second direction different from the first direction.
The clothes mover can be an agitator.
The clothes mover can comprise a plurality of the vanes. The plurality of the vanes can be equally spaced. The vanes can be oriented radially relative to the vertical axis.
In the drawings:
Referring now to the drawings and particular to
Each of the tub 20 and basket 22 comprises a closed bottom 20a, 22a and a peripheral wall 20b, 22b extending upwardly from the corresponding bottom 20a, 22a and terminating in an upper edge 20c, 22c, which defines an open top. The peripheral walls 20b and 22b are preferably cylindrical resulting in the open top having a circular shape.
A wash liquid system (not shown) is commonly used to introduce wash liquid onto clothing placed in the basket 22. The wash liquid can comprise water or a mixture of water with wash aid, such as detergent. The wash liquid system normally comprises a wash aid dispenser and a water inlet along with a pump coupled to the tub for draining or recirculating the wash liquid from the tub. The type of wash system is not germane to the invention. There are many well-known wash systems. One common type of wash system is the immersion type, which at least partially fills the basket 22 and tub 20 with wash liquid to clean the clothes while they are immersed in the wash liquid. Another common wash system is a reciprocating wash liquid system that reciprocates wash liquid through the clothing. Some systems are capable of both immersion and reciprocation, with the selection of a particular method being dependent on a particular wash cycle.
An agitator assembly 30 according to one embodiment of the invention is mounted within the basket 22 and rotates relative to the basket 22 to aid in cleaning the clothing. The agitator assembly 30 comprises an auger 32 and an agitator 34, which can rotate relative to one another about a common, vertical axis. The auger 32 couples with the agitator 34 through a drive mechanism, such as a unidirectional clutch (not shown). Rotation of the auger 32 moves the clothing downwardly from the surface of the wash liquid and towards the agitator 34. A motorized drive mechanism reciprocally rotates the agitator 34 clockwise and counterclockwise about the common axis such that the agitator 34 oscillates and simultaneously moves the clothing outward towards the basket 22 and upward towards the surface of the wash liquid where it is pushed downward again by the auger 32. Hence, the agitator assembly 30 moves the clothing along a toroidal path defined between the agitator assembly 30 and the basket 22. One full cycle along the toroidal path is commonly referred to as a rollover.
Both the auger 32 and agitator 34 will be described in further detail.
While the auger vane 50 can have any suitable length, the auger vane 50 in the illustrated embodiment spirals from near the upper end 42a of the body 40 to near the lower end 44a of the body 40. The auger vane 50 is formed by multiple ledges 52, wherein adjacent ledges 52 are joined by a step 54. Each ledge 52 is bounded by a trailing first end 56 and a leading second end 58, and, similarly, each step 54 is bounded by a trailing first end 60 and a leading second end 62. The ledges 52 and steps 54 are arranged such that the first ends 60 of the steps 54 coincide with the second ends 58 of the ledges 52, and the second ends 62 of the steps 54 coincide with the first ends 56 of the ledges 52. In other words, one step 54 connects the second end 58 of one ledge 52 with the first end 56 of an adjacent ledge 52. Further, each ledge 52 has an upper surface 55 and a lower surface 57, and each step 54 has an upper surface 61 and a lower surface 63.
The ledges 52 are attached to the body 40 at a root 64 and extend outwardly to a tip 66. According to the illustrated embodiment of the invention, the tip 66 forms a helix around the tubular body 40. The ledges 52 taper slightly from the root 64 to the tip 66, and, as seen in
The ledges 52 are preferably undercut and oriented at an angle α relative to the body 40 to provide a recess 68 between the tip 66 and the outer surface 44 of the body 40. The undercut angle α, which is measured between the peripheral surface 48 of the body 40 and the lower surface 57 of the ledge 52, can gradually increase from the first end 56 of the ledge 52 to the second end 58 of the ledge 52.
Referring again to
To achieve a helical configuration, the auger vane 50 extends along the body 40 at a predetermined slope. The slope determines a pitch P, as shown in
As discussed above, the performance of the auger 32 depends on several geometric characteristics of the auger vane 50. Specifically, the performance is a function of the undercut angle α, the pitch P, and the auger vane width W. Further, it is preferred that the root 64 has a small thickness T to alleviate problems related to the shape of the body 40 and production of the auger 32. In prior art augers, wherein the auger vane lacks the steps 54, the desired undercut angle α and the desired pitch P necessarily correspond to a thick root 64 and a limited auger vane width W. However, because the auger vane 50 of the present invention includes the steps 54, the draft angle θ is not restricted by the undercut angle α or the pitch P. The steps 54 vertically space adjacent ledges 52 by a distance equal to the height H of the step 54, and, thus, the steps 54 enable the auger vane 50 to achieve the desired pitch P that corresponds to the predetermined slope with the individual ledges 52 having a slope less than the predetermined slope. Consequently, the draft angle θ of the ledges 52 and the resulting root thickness T and maximum vane width Wmax can be selected independent of the undercut angle α and the pitch P in order to improve rollover and cleaning performance and to avoid the aforementioned problems, such as warpage of the body 40 and sinks on the inner surface 46 of the body 24, commonly encountered when the root 64 is thick. The number of the steps 54 in one turn of the auger vane 50 and the height H of each step 54 can be adjusted to achieve the desired pitch P and the desired slope of each individual ledge 52.
Referring now to
The skirt portion 90 comprises a skirt 96 that flares outward from a sloped inner perimeter ring 92 to a circular outer perimeter 94 having a depending flange 98. The skirt 96 includes multiple vents 100 near the inner perimeter ring 92 for filtering the wash liquid as it passes therethrough. The skirt 96 further comprises several circumferentially spaced depressions 102 near the outer perimeter 94. Each depression 102 is formed by a right wall 104 and an opposing left wall 106 that abut at a corner 108 and an inclined, substantially triangular bottom wall 110 that joins the right and left walls 104, 106 along their bottom edges.
To facilitate movement of the clothing along the toroidal path, the skirt portion 90 further comprises multiple fins 112 and agitator vanes 120. The fins 112 are circumferentially spaced and extend radially outward from the intermediate ring 88 to the skirt 96. Preferably, the fins 112 are relatively short and terminate at a location on the skirt 96 near the outermost vents 100; however, it is within the scope of the invention for the fins 112 to terminate ahead of or beyond the outermost vents 100.
Referring additionally to
As seen in
The agitator vane 120 is preferably integral with the skirt 96 and connected to the skirt 96 from the upper connection point 148 to the lower connection point 146, as best viewed in
As shown in
The combination of the shape of the agitator vane 120, the variable thickness of the tail 128, and, primarily, the material of the agitator vane 120 enables the agitator vane 120 to flex in multiple directions and about multiple axes, and, as a result, the agitator vane 120, unlike the prior art agitators, applies an upward force directly to the clothing in addition to an outward force as the agitator 34 moves the clothing from the auger 32 to the peripheral wall 22b of the basket 22. The flexed positions of the tail 128 are shown in phantom lines in
It should be understood that while for ease of description the flexing of the vane along the directions of arrows A and B are described independently, the two types of flexing can and will occur simultaneously and form a compound flexing during the operation of the agitator.
Because the agitator 34 moves the clothing upward in addition to outward, the washing machine 10 is more effective and more efficient than washing machines having prior art agitators that only move the clothing outward. For example, the upward movement of the clothing prevents clothing from collecting at the bottom of the basket 22 and helps the move clothing along the toroidal path to improve the cleaning performance. Additionally, the mechanical energy requirements of the agitator 34 are reduced, which corresponds to lower electrical energy consumption, lower maximum motor torque, and lower motor temperature.
As indicated above, the performance of the agitator 34 depends on several factors, and a primary factor is the agitator vane material. Performance tests involving agitators 34 having agitator vanes 90 constructed of materials with differing flexural moduli yielded the results listed in Table I. Table I includes the following performance parameters:
Electrical Energy=average consumption of electrical energy during agitation
Mechanical Energy=average mechanical energy applied to the clothing by the agitator during agitation
Effectivness=Mechanical Energy/Electrical Energy
Motor Temperature=average temperature increase of the motor during agitation
Maximum Speed=maximum rotational speed of the agitator during agitation
Maximum Torque=maximum torque of the motor during agitation Cycle Time=average time of a full reciprocating agitation cycle
When the agitator vanes 120 are made of Santoprene 203-50 compared to polypropylene, the motor that drives the agitator 34 consumes less electrical energy, and the conversion of the electrical energy into mechanical energy applied to the clothing is more efficient. Further, the increase in the motor temperature and the maximum torque of the motor are both significantly reduced. Consequently, the agitator 34 with the Santoprene 203-50 agitator vanes 120 is more energy efficient and less demanding on the motor compared to the agitator 34 with the polypropylene agitator vanes 120. Further improvements can be achieved with Santoprene 101-55; however, the Santoprene 101-55 is extremely flexible and not preferred for use in the agitator vanes 120. The agitator vanes 120 must be strong enough to at least partially support the weight of the clothing as it moves across the agitator 34.
When the agitator assembly 30 is assembled, the agitator barrel 80 is disposed within the lower portion 44 of the auger body 40, and the lower end 44a of the auger body 40 abuts the intermediate ring 88 of the auger 32. As discussed previously, the agitator 34 couples to the motorized drive mechanism through the drive connection 86, and the auger 32 couples with the agitator 34 through the drive mechanism.
During operation of the agitator assembly 30, the motorized drive mechanism reciprocally rotates the agitator 34 clockwise and counterclockwise, and the auger 32 rotates with the agitator 34 in one of the directions and is stationary while the agitator 34 rotates in the other direction. As the agitator assembly 30 rotates, the auger 32 moves the clothes downward from the surface of the wash liquid towards the agitator 34, and the agitator fins 112 move the clothing radially outward while the agitator vanes 120 move the clothing radially outward and upward along the peripheral wall 22a of the basket 22. The clothing continues along the toroidal path towards the surface of the wash liquid and back to the auger 32.
Although the agitator assembly 30 has been shown and described as comprising the auger 32 and the agitator 34, it will be apparent to one of skill in the washing machine art that the agitator 34 can be used without the auger 32 or with a different auger. Similarly, the auger 32 can be utilized in combination with an agitator other than the agitator 34 described herein or other clothes and/or wash liquid mover, such as an impeller or a nutator. Furthermore, the agitator vanes 120 have been described thus far as being integral with the skirt portion 90. However, it is within the scope of the invention for the agitator vanes 120 to be separate from the skirt portion 90 and attached thereto with, for example, mechanical fasteners, adhesives, or joining processes, such as heat staking. Additionally, the vanes 120 can be incorporated into another type of clothes mover other than an agitator, such as an impeller or nutator.
A second embodiment agitator 34′ is illustrated in
A third embodiment agitator 34″ is shown in
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, and the scope of the appended claims should be construed as broadly as the prior art will permit.
This application claims the benefit of U.S. Patent Application No. 60/521,746, filed Jun. 29, 2004.
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| Number | Date | Country | |
|---|---|---|---|
| 20050284196 A1 | Dec 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60521746 | Jun 2004 | US |
