Patent Application
20120186611
1. Field of the Invention
The present invention pertains to the art of dishwashers and, more particularly, to a dampened pump assembly for a dishwasher.
2. Description of the Related Art
Certainly, it is desirable to produce a dishwasher which is quiet in operation. To this end, it is known in the art of dishwashers to utilize insulation and other barriers to reduce low frequency noises generated during the operation of motors for fluid recirculation and drain pumps. It is also known to attach freely oscillating mass components to a motor via elastic linkage components for damping the vibrations of the motor, such as discussed in U.S. Patent Application Publication No. 2004/0055410. Such oscillating mass components need to be tuned to a specific resonant frequency corresponding to specific motor vibrations. Initially, such an arrangement is quite effective but, in addition to being rather complicated and expensive to produce, generally requires re-tuning over time to remain effective. There also exist other solutions to noise reduction, with these solutions having varying levels of success in the reduction of noises emanating from dishwashers due to the operation of fluid pumps and drain motors. Regardless, there is still seen to be a need for an extremely cost effective, robust and efficient noise reduction arrangement for a dishwasher.
The present invention is directed to the inclusion of a mass damper on a pump assembly of a dishwasher in order to reduce vibrations, generated by the dishwasher pump, in a broad frequency range. More specifically, a dishwasher in accordance with the invention incorporates a dampened pump assembly including a housing having a base to which is mounted a pump and motor unit configured to develop a flow of washing fluid during operation of the dishwasher. A mass damper is mounted to the housing, with the mass damper substantially conforming to the shape and being rigidly fixed to a portion of the housing at a position offset from the pump and motor unit. The mass damper provides added weight to the pump assembly which reduces vibrations throughout the dishwasher caused by operation of the pump and motor unit.
In accordance with preferred embodiments of the invention, the base of the pump assembly also forms part of a sump unit, including a sump enclosure. The mass damper takes the form of a housing which extends over and about the sump enclosure. Exposed to the sump enclosure are ports which are fluidly connected to a recirculation pump unit and a drain pump unit respectively. With this arrangement, the mass damper housing adds a significant amount of weight at the sump enclosure where vibrations can be generated due to turbulent fluid flow there through, while also being effectively offset from the recirculation and drain pump units in order to provide a more stable center of gravity.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.
With initial reference to
Disposed within an opening (not labeled) of tub 5 is a pump and filtration assembly generally indicated at 30. In the preferred embodiment, pump and filtration assembly 30 includes a central main strainer or filter screen 36 and a secondary, fine strainer 39. Extending about a substantial portion of pump and filtration assembly 30, at a position raised above bottom wall 8, is a heating element 44. In a manner known in the art, heating element 44 preferably takes the form of a sheath, electric resistance-type heating element.
Dishwasher 2 further includes a water distribution manifold indicated at 53. In a manner known in the art, water distribution manifold 53 supplies washing fluid to at least a lower wash arm 55 and a conduit 57 leading to an upper spray arm (not shown). Additionally, water distribution manifold 53 may be in fluid communication with a spray manifold assembly 59 including a plurality of spray discs 62. The manner in which wash arm 54 and spray manifold assembly 59 are utilized is known in the art, such that this structure will not be described further herein. Certainly, during operation of pump and filtration assembly 30, vibrations will be generated. The present invention is specifically directed to dampening these vibrations as will be detailed below.
With reference to
As also shown in this figure, pump and filtration assembly 30 also includes a drain pump unit 106 including a pump portion 108 having an inlet conduit 111 connected to an outlet 114 or second mounting port of sump enclosure 80. Pump portion 108 of drain pump unit 106 also includes an outlet conduit or drain 117. Finally, drain pump unit 106 also includes an electric motor 120 for driving pump portion 108.
In a manner known in the art, dishwasher 2 can operate to wash dishware by activating a washing cycle wherein water will be directed into main intake 81 in order to fill sump enclosure 80 and a lower portion of tub 5. At the same time, the water will flow into circulation pump unit 88 and water distribution manifold 53. During a normal washing operation, circulation pump unit 88 is activated to draw washing fluid from sump enclosure 80 through outlet 84 and inlet conduit 86, while directing the washing fluid through outlet conduit 95, water distribution manifold 53 and then to wash arm 55, conduit 57 and manifold assembly 59. When the overall washing cycle calls for a drain operation, circulation pump unit 88 is deactivated and drain pump unit 106 is operated to cause fluid to be drawn from sump enclosure 80 through secondary outlet 114 and inlet conduit 111, with the water being discharged through drain 117. Again, this overall operation of dishwasher 2 is known in the art and is presented for the sake of completeness. Most importantly, in connection with the present invention is the fact that operation of circulation pump unit 88 and/or drain pump unit 106 during an overall washing cycle will generate vibrations which attenuate into tub 5 and result in undesirable noises emanating from dishwasher 2. To minimize these vibrations and counter the potential noise generation, pump and filtration assembly 30 in accordance with the present invention is provided with a mass damper housing 130 mounted about sump enclosure 80.
As shown in these figures, mass damper housing 130 includes a base 135 and a peripheral side wall 138. Arranged in base 135 is a pair of spaced bores 141 and 142. As illustrated, each of bores 141 and 142 is preferably formed with a first, uniform diametric portion 145 which leads to a second, enlarged and tapering diametric portion 146. In addition, the portion of peripheral side wall 138 remote from base 135 is provided with a beveled edge 149 leading to a terminal edge 153. Along a portion of peripheral side wall 138 is formed an arcuate cut-out portion 158 for reasons which will be discussed more fully below. Finally, in the embodiment depicted, base 135 is actually formed with various, varying thickness portions including a first thickness portion 161, a second thickness portion 162 and a third, varying thickness portion 163. As best illustrated in
As clearly shown in
The concept of conforming to the structure in which it is mounted and providing the mass damping effect desired in accordance with the invention will also become more fully evident in considering the remaining disclosure, starting with a second embodiment shown in
As clearly illustrated, mass damper housing 180 is mounted upon and about sump enclosure 80′ and adjacent structure. More specifically, posts 197 and 198 are received within cavities 193 and 194 and fasteners 223 and 224 are extended through bores 190 and 191 and threaded into posts 197 and 198. Upon mounting, arcuate cut-out portion 203 extends closely adjacent and conforms to outlet 84 of the sump unit 76, while arcuate cut-out portion 207 closely conforms to secondary outlet 114. At the same time, notch 211 accommodates a post 225 which is molded in order to establish an alignment and mounting aid. At this point, as with the discussion set forth above, it should be readily recognized that mass damper housing 180 is specifically constructed to conform closely to the structure of sump enclosure 80′ and about additional portions thereof including associated outlets.
As in the case of mass damper housing 130, mass damper housing 180 is also formed of a heavy material, such as concrete, steel, iron or the like, so as to have a significant weight in the range of 1-6 lbs. The inclusion of this additional weighted structure in accordance with the present invention performs a significant mass dampening effect which minimizes the development of vibrations, particularly during certain operational phases of circulation pump unit 88 and drain pump unit 106. The significant reduction of noise is represented in
Although described with reference to preferred embodiments of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, although shown in connection with a conventional dishwasher having a pivoted front door, it should be readily apparent that the invention can also be applied to other types of dishwashers, including drawer-type dishwashers. In addition, although the material used to make the mass damper and the mounting thereof can vary, it is important that the main body portion of the mass damper substantially conform and be rigidly fixed to a portion of a pump housing which is at a position offset from the pump and motor unit, with the mass damper being weighted to reduce vibrations throughout the dishwasher caused by the operation of the pumping motor unit. Finally, it should be noted that although the preferred embodiments provide separate recirculation and drain pumps, it is widely known in the art to utilize a reversible pump assembly which performs both functions. Still, the mass damper housing would conform to and be mounted offset from that pump and motor unit in accordance with the invention. In general, the invention is only intended to be limited by the scope of the following claims.
