Abstract:
A food waste disposer system ( 300 ) has active noise control of food waste disposer noise that is generated by the food waste disposer ( 302 ) when a motor of the food waste disposer ( 302 ) is running. The food waste disposer ( 302 ) has a food conveying section that conveys food waste to a grinding section. The grinding section has a rotatable shredder plate that is rotated by a motor of a motor section. Active noise sound waves ( 310 ) are radiated into an area ( 313 ) where the food waste disposer noise is to be controlled at an amplitude and frequency to at least cancel or mask the food waste disposer noise.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/074,257 filed Nov. 3, 2015. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to food waste disposers, and more particularly, to food waste disposer noise reduction using active noise control. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure, which is not necessarily prior art. 
         [0004]    A food waste disposer of the type that is disposed underneath a sink and is mounted to a drain opening of the sink typically includes a food conveying section, a motor section and a grind section. The grind section is disposed between the food conveying section and the motor section. The food conveying section conveys food waste and water to the grind section. The grind section receives and grinds the food waste and the ground food waste is discharged through a discharge opening to a tailpipe. 
         [0005]    The grind section typically includes a grind mechanism with a rotating shredder plate assembly and a stationary grind ring. The shredder plate assembly is connected to a shaft of an electric motor of the motor section and includes a shredder plate with one or more lugs, typically one or more pairs of lugs. The lugs may include fixed lugs that are fixed to the shredder plate, rotatable lugs (also called swivel lugs) that are rotatably fastened to the shredder plate and are free to rotate thereon, or both. The shredder plate is rotated relative to the grind ring via the electric motor. The grind ring is typically mounted in a housing and includes multiple spaced teeth. 
         [0006]    The operational noise of a food waste disposer is a combination of grinding noise, water spectrum, and motor noise. Grinding noise arises from the interaction of the food waste with the grind mechanism components and the container body. It is characterized by random impulsive noise events from impacts and it changes over time as the food waste is broken up and discharged to the drain line. The water spectrum noise arises from the running water exiting the faucet, impinging upon the sink, and being moved about within the food waste disposer. Motor noise is typically a steady state noise with a consistent frequency content but it can vary from unit to unit as the characteristics of motor noise are highly affected by bearing alignment and variations in rotor/stator air gap. 
         [0007]    Passive noise control is currently used to reduce the operational noise levels of food waste disposers. Passive methods include the use of (1) absorbent and barrier materials to absorb and/or block sound energy traveling through the container body or motor housing, (2) vibration isolation mounts at the sink and plumbing interfaces to reduce structure borne noise from the sink and plumbing, and (3) use of baffling at the throat opening to attenuate air borne noise from the grind chamber. Passive methods have been effective in reducing the noise levels perceived by the user during operation of the food waste disposer. However, there are practical constraints to how much noise reduction can be achieved by these means, especially in frequency ranges 1 kHz and lower. 
         [0008]      FIG. 1  depicts a prior art food waste disposer  100  which is similar to the prior art food waste disposer described in U.S. Pat. No. 7,360,729 the entire disclosure of which is incorporated herein by reference. The disposer includes an upper food conveying section  102 , a central grinding section  104  and a motor section  106 , which may include a variable speed motor. It should be understood that motor section  106  could also include a fixed speed motor, such as an induction motor. The grinding section  104  is disposed between the food conveying section  102  and the motor section  106 . 
         [0009]    The food conveying section  102  conveys the food waste to the grinding section  104 . The food conveying section  102  includes an inlet housing  108  and a conveying housing  110 . The inlet housing  108  has an inlet  109  at the upper end of the food waste disposer  100  for receiving food waste and water. Inlet  109  is surrounded by a gasket  111 . The inlet housing  108  is attached to the conveying housing  110 , such as by an antivibration mount  113 . 
         [0010]    The conveying housing  110  has an opening  142  to receive a dishwasher inlet  144 . The dishwasher inlet is used to pass water from a dishwasher (not shown). The inlet housing  108  and conveying housing  110  may be made of metal or molded plastic. Alternatively, inlet housing  108  and conveying housing  110  may be one unitary piece. 
         [0011]    The grinding section  104  includes a housing  112  surrounding a grinding mechanism  114  having a rotating shredder plate assembly  116  and a stationary grind ring  118 . Housing  112  is formed as a clamp ring and clamps conveying housing  110  to an upper end bell  136  of motor section  106 . Stationary grind ring  118 , which includes a plurality of spaced teeth  120  (only two of which are indicated by reference number  120  in  FIG. 1 ), may be received in an adaptor ring  122  disposed between housing  112  and stationary grind ring  118 . A gasket  123  is disposed between adaptor ring  122  and an upper portion  125  of housing  112 . A bottom flange  127  of conveying housing  110  is received in gasket  123  and gasket  123  seals conveying housing  110  to adaptor ring  122 . 
         [0012]    The rotating shredder plate assembly  116  may include a rotating shredder plate  124  mounted to a rotatable shaft  126  of a motor  128  of motor section  106 , such as by a bolt  130 . Motor  128  also includes a rotor  129  to which rotatable shaft  126  is affixed and a stator  131 . A plurality of fixed lugs  132  (only one of which is shown in  FIG. 1 ) are mounted on rotating shredder plate  124  as are a plurality of swivel lugs  134  (only one of which is shown in  FIG. 1 ). It should be understood that in this regard, rotating shredder plate assembly  116  could include only fixed lugs  132  or only swivel lugs  134 . 
         [0013]    An upper end bell  136  is disposed beneath a bottom of rotating shredder plate  124 . Upper end bell  136  includes a discharge chamber  140  having a discharge outlet  141  for coupling to a tailpipe or drainpipe (not shown). 
         [0014]    In an aspect, food waste disposer  100  may include a trim shell  146  that surrounds food conveying section  102 , grinding section  104  and motor section  106 . A layer of sound insulation  148  may be disposed between trim shell  146  and conveying housing  110  of food conveying section  102  and housing  112  of grinding section  104 . 
         [0015]    Food waste disposers such as food waste disposer  100  are often generally installed to a sink in a two-step procedure using a mounting assembly  200  of the type described in U.S. Pat. No. 9,139,990. With reference to  FIG. 2 , first, a sink flange assembly  202 , consisting of a sink flange  204 , sink gasket  206 , back-up flange  208 , upper mounting flange  210 , bolts  212 , and retaining ring  214  are installed to the sink (not shown). Second, a disposer assembly consisting of a disposer such as disposer  100  ( FIG. 1 ), a mounting gasket  216  (which is mounting gasket  111  in  FIG. 1 ), and a lower mounting flange  218  are attached to the sink flange assembly. Lower mounting flange  218  is placed around inlet housing  108  of food conveying section  102  so that it is beneath inlet  109 . Mounting gasket  216  is then placed around inlet  109 . Inlet housing  108  of food conveying section  102  includes circumferential lip  188  extending around the circumference of inlet  109 . Lip  188  is received in a corresponding recess (not shown) in mounting gasket  216  to secure mounting gasket  216  to food waste disposer at inlet  109 . The attachment method, as described in U.S. Pat. No. 9,139,990, consists of engaging the mounting tabs  220  of the lower mounting flange  218  with the inclined mounting ramps  222  of the upper mounting flange  210  then rotating the lower mounting flange  218  until secure. The typical installation method involves raising the disposer  100  and mounting components to the sink flange assembly  202  with one hand then with the other hand lifting the lower mounting flange  218  and rotating to engage its mounting tabs  220  to the mounting ramps  222  of upper mounting flange  210 . Rotating the lower mounting flange  218  brings it and upper mounting flange  210  securely together, compressing the mounting gasket  216  therebetween, and secures the disposer  100  to the sink flange assembly  202 . 
         [0016]    In the operation of the food waste disposer  100 , the food waste delivered by the food conveying section  102  to the grinding section  104  is forced by lugs  132 ,  134  of the rotating shredder plate assembly  116  against teeth  120  of the stationary grind ring  118 . The sharp edges of the teeth  120  grind or comminute the food waste into particulate matter that combines with water, such as water that entered the food waste disposer through inlet  109 , to form a slurry that drops into discharge chamber  140 . This slurry is then discharged through the discharge outlet  141  into the tailpipe or drainpipe (not shown). 
       SUMMARY 
       [0017]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0018]    A food waste disposer system has active noise control of food waste disposer noise that is generated by the food waste disposer when a motor of the food waste disposer is running. The food waste disposer has a food conveying section that conveys food waste to a grinding section. The grinding section has a rotatable shredder plate that is rotated by a motor of a motor section. Active noise sound waves are radiated into an area where the food waste disposer noise is to be controlled at an amplitude and frequency to at least cancel or mask the food waste disposer noise. 
         [0019]    In an aspect, the active noise sound waves are radiated at an amplitude and a frequency to both cancel and mask the food waste disposer noise. 
         [0020]    In an aspect, the active noise sound waves are radiated into an interior of the food conveying section of the food waste disposer. In an aspect, the active noise sound waves are radiated from a portion of an active noise source that extends through a wall of a housing of the food conveying section. In an aspect, the active noise sound waves are radiated from an active noise source disposed in a stopper received in a sink drain outlet of a sink to which the food waste disposer is mounted. 
         [0021]    In an aspect, the active noise sound waves are radiated into an interior of a tubular body portion of a sink flange to which the food waste disposer is mounted. In an aspect, the active noise sound waves are radiated from a portion of an active noise source that extends through a wall of the tubular body portion of the sink flange. 
         [0022]    In an aspect, the area is above an inlet at an upper end of the food waste disposer and the active noise sound waves are radiated to the area above the inlet at the upper end of the food waste disposer from an active noise source disposed in a stopper received in a sink drain outlet of a sink to which the food waste disposer is mounted. 
         [0023]    In an aspect, the active noise sound waves are radiated in an interior of a cabinet in which the food waste disposer is disposed. In an aspect, the active noise sound waves are radiated by an active noise source disposed in the cabinet. 
         [0024]    In an aspect, the active noise sound waves are generated by vibrating a wall of a sink to which the food waste disposer is mounted. 
         [0025]    In an aspect, the active noise sound waves are generated by vibrating a wall of the cabinet in which the food waste disposer is disposed 
         [0026]    In an aspect, the active noise are generated by vibrating a wall of a conveying housing of a food conveying section of the food waste disposer or vibrating a wall of a tubular body portion of a sink flange to which the food waste disposer is mounted. 
         [0027]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0028]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0029]      FIG. 1  is a sectional view of a prior art food waste disposer; 
           [0030]      FIG. 2  is an exploded view of a prior art mounting assembly for mounting a food waste disposer to a sink; 
           [0031]      FIG. 3  is a sectional view of an upper portion of a food waste disposer system having active noise control with an active noise source disposed in a wall of a conveying housing of a food conveying section of the food waste disposer in accordance with an aspect the present disclosure; 
           [0032]      FIG. 4  is a sectional view of an upper portion of a food waste disposer system having the active noise source disposed in a wall of a tubular body of a sink flange to which the food waste disposer is attached accordance with another aspect the present disclosure; 
           [0033]      FIG. 5  is a sectional view of an upper portion of a food waste disposer system having the active noise source disposed in a stopper received in a drain opening of a sink to which the food waste disposer is mounted in accordance with another aspect the present disclosure; 
           [0034]      FIG. 6  is a sectional view of an upper portion of a variation of the food waste disposer system of  FIG. 5  in which the active noise source is disposed to radiate active noise sound waves to an area above an inlet at an upper end of the food waste disposer in accordance with another aspect of the present disclosure; 
           [0035]      FIG. 7  is a perspective view of a food waste disposer system having an active noise source disposed in a housing attached to the motor section of the food waste disposer in accordance with another aspect of the present disclosure; 
           [0036]      FIG. 8  is a perspective view of a food waste disposer system having an active noise source disposed in a cabinet in which the food waste disposer is disposed; 
           [0037]      FIG. 9  is a perspective view of a food waste disposer system having active noise control in which active noise sound waves are generated by a vibration transducer in contact with a wall of a sink to which the food waste disposer is mounted in accordance with another aspect of the present disclosure; and 
           [0038]      FIG. 10  is a perspective view of a food waste disposer system having active noise control in which active noise sound waves are generated by a vibration transducer in contact with a wall of a cabinet in which the food waste disposer is disposed in accordance with another aspect of the present disclosure 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0040]    In accordance with an aspect of the present disclosure, active noise control is used to reduce noise of a food waste disposer. Active noise control can include noise masking and/or noise cancellation. Noise masking involves generating a broad spectrum noise field with a frequency content and amplitude that effectively “masks” or covers up annoying noises emanating from the food waste disposer. Noise masking does not actually reduce the amount of noise, but instead distracts the operator from being annoyed by the sound of the food waste disposer. Noise cancellation is the superposition of a canceling sound wave with the sound wave emanating from the disposer. The canceling sound wave is essentially the negative of the propagating sound wave (opposite phase) so that when the propagating sound wave and the canceling sound wave are superimposed, the result is a zero to low level sound. 
         [0041]    Applying active noise control to the food waste disposer involves measuring the sound to be cancelled or masked, generating the appropriate cancelling or masking signal, and then playing that signal through a speaker located in or near the food waste disposer. In the case of effective global noise cancelling the noise is cancelled at the source (disposer) and this reduces the overall loudness at any location in the household. In the case of noise masking, it is preferable to minimize the amount of dynamics in the masking signal in order to reduce likelihood that the operator will notice its presence. The amounts of active noise canceling and sound masking can both be manipulated with a high degree of accuracy. 
         [0042]    Referring to  FIG. 3 , a food waste disposer system  300  having active noise control is shown. Food waste disposer system  300  includes a food waste disposer  302  having an active noise source  304  that radiates active noise sound waves into an area where food waste disposer noise generated when a motor of the food waste disposer is running is to be controlled. Illustratively, food waste disposer  302  is the same as food waste disposer  100  except for the addition of active noise source  304  and the following discussion will focus on the differences. In the example of  FIG. 3 , a portion  306  of active noise source  304  extends through a wall  308  of conveying housing  110  of food conveying section  102  and radiates active noise sound waves  310  into an interior  312  of food conveying section  102  with the interior  312  constituting an area  313  in which the food waste disposer noise is to be controlled. Portion  306  is illustratively an end portion of active noise source  304  and will hereafter be referred to as end portion  306 . Active noise source  304  is disposed in a protective housing  314  with a protective membrane  316  at end portion  306  of active noise source  304 . Active noise source  304  is coupled to an active noise drive circuit  318  that drives active noise source  304 . Active noise source  304  is illustratively an audio transducer and may for an example be an audio speaker but can be other types of audio transducers such as piezoelectric audio transducers. Active noise drive circuit  318  is for an example a circuit including a signal generator and audio amplifier that amplifies an output of the signal generator. In an aspect, active noise drive circuit is programmable as to frequency, amplitude, or both. 
         [0043]    In an aspect, active noise circuit  318  adaptively programs itself to function in frequency ranges which are prevalent in the system. In an aspect, active noise circuit  318  utilizes feedback control, in an aspect, active noise circuit uses feed forward control, and in an aspect, active noise circuit utilizes a combination of feedback and feed forward control. 
         [0044]    As an example and not by way of limitation, active noise circuit  318  is configured, such as by programming, to implement a control methodology commonly known to those of skill of the art as Filtered-X least means squared feedforward control. The Filtered-X indicates that a source signal is passed through an adaptive finite impulse response signal to form the control signal. Initially, the filter coefficients are set to zeros, and then the control algorithm adapts the filter to minimize the error signal at each step, which is how control of impulsive signals is achieved. The filter is illustratively designed to function in a certain frequency range, such as a 120 Hz peak or less than 1000 Hz. 
         [0045]    With reference to  FIG. 4 , in an aspect, a food waste disposer system  400  has end portion  306  of active noise source  304  extending through a wall  402  of a tubular body portion  404  of sink flange  204  to which food waste disposer  100  is mounted. Active noise source  304  radiates active noise sound waves  310  into an interior  406  of tubular body portion  404  as shown in  FIG. 4  with the interior  406  being an area  407  in which the food waste disposer noise is to be controlled. 
         [0046]    With reference to  FIGS. 5 , in an aspect, a food waste disposer system  500  has an active noise source  502  disposed in a stopper  504  that is received in a sink drain outlet  506  of a sink  508  in which sink flange  204  to which food waste disposer  100  is mounted is received. It should be understood that stopper  504  is received in sink drain outlet  506  by being received in sink flange  204  which is received in sink drain outlet  506 . In an aspect, active noise source  502  is disposed between protective membranes  512  that are also disposed in stopper  504 . Active noise source  502  is illustratively also an audio transducer and is coupled to active noise drive circuit  318 . In the aspect shown in  FIG. 5 , the active noise source  502  is disposed in stopper  504  to radiate active noise sound waves  310  into interior  312  of the food conveying section  102  of food waste disposer  100 . In an aspect, stopper  504  is a stopper of the type described in U.S. Pat. No. 9,145,666 the entire disclosure of which is incorporated herein by reference. 
         [0047]    In a variation of the food waste disposer system of  FIG. 5 , active noise source  502  disposed in stopper  504  radiates active noise sound waves  310  to an area  602  ( FIG. 6 ) external to food waste disposer  100 . In an aspect, area  602  is an area  604  above an inlet  109  at the upper end of food waste disposer  100  and the active noise source is disposed in stopper  504  to radiate active noise sound waves  310  into the area  604  above inlet  109 . 
         [0048]    With reference to  FIG. 7 , in an aspect, a food waste disposer system  700  includes a food waste disposer  702  having an active noise source  704  and active noise drive circuit  318  disposed in a housing  706  attached to motor section  106 . It should be understood that housing  706  could be attached to other sections of food waste disposer  702 , such as upper food conveying section  102  or central grinding section  104 . 
         [0049]    With reference to  FIG. 8 , a food waste disposer system  800  includes food waste disposer  100  mounted to a sink  804  with food waste disposer  802  disposed in a cabinet  806  with sink  804  received in a top of cabinet  806 . An active noise source  808  is spaced from the food waste disposer  802  in cabinet  806  and radiates active noise sound waves  310  into an interior  810  of cabinet  806  with interior  810  being an area  811  in which the food waste disposer noise is to be controlled. 
         [0050]    In each of the foregoing aspects, it should be understood that more than one active noise source can be used with the different active noise sources located at different ones of the above described locations. 
         [0051]    In an aspect, vibration excitation could also be used to generate the cancelling or masking noise. Vibrational excitation of either the cabinet or sink can cause the cabinet or sink to radiate noise. Stainless steel kitchen sinks which are used in the majority of US households are effective radiators of sound. The sink itself acts as a speaker and when excited by a vibration signal, will radiate sound. Thus, in an aspect, an alternative means of creating a masking or cancelling signal for the operational noise of the food waste disposer is to use the structural response of the sink to a vibrational source as the source to generate the needed signal, use the structural response of the cabinet to a vibrational source as the source to generate the needed signal, or both. A drawback of this approach is that sink and cabinet characteristics are variable from installation to installation so the effectiveness of these alternatives may be site dependent. In this approach, an adaptive control method would be used and the adaptive nature of the control method will try to achieve noise cancellation within the means of the vibration source but there will be some range of system parameters (stiffness, damping) where the system would not be able to perform, but it will try to adapt to the site conditions as much as possible.  FIGS. 9 and 10  show examples of the foregoing aspects. 
         [0052]    With reference to  FIG. 9 , a food waste disposer system  900  has food waste disposer  100  mounted to a sink  902 . Food waste disposer  100  is illustratively disposed in a cabinet  904  with sink  902  received in a top of cabinet  904 . A vibration transducer  906  is in contact with a wall  908  of sink  902 . Vibration transducer  906  is coupled to a vibration drive circuit  910 . Vibration transducer  906 , driven by vibration drive circuit  910 , vibrates wall  908  of sink  902  at an applicable frequency to generate the active noise sound waves. Vibration transducer  906  is for example a piezoelectric transducer, but can be other types of transducers that vibrate in response to an electrical drive signal. 
         [0053]    With reference to  FIG. 10 , a food waste disposer system  1000  has food waste disposer  100  mounted to a sink  902 . Food waste disposer  100  is illustratively disposed in cabinet  904  with sink  902  received in the top of cabinet  904 . A vibration transducer  906  is in contact with a wall  912  of cabinet  904 . Vibration transducer  906  is coupled to vibration drive circuit  910 . Vibration transducer  906 , driven by vibration drive circuit  910 , vibrates cabinet wall  912  at an applicable frequency to generate the active noise sound waves. 
         [0054]    It should be understood that the vibration transducer could be located at locations other than wall  908  of sink  902  or cabinet wall  912 . For example, vibration transducer  906  could be disposed in wall  308  of conveying housing  110  instead of active noise source  318  or in wall  402  of tubular body portion  404  of sink flange  204  (shown in phantom in  FIG. 4 ). In these examples, wall  308  of conveying housing  110  or wall  402  of tubular body portion  404  of sink flange  204  are vibrated to generate the active noise sound waves. 
         [0055]    It should be understood that in each of the above described aspects, the food waste disposer can have a layer of sound insulation such as sound insulation  148  ( FIG. 1 ) or not have it. 
         [0056]    It should be understood that active noise drive circuit  318  or vibration drive circuit  910  may be, be part of, or include an Application Specific Integrated Circuit (ASIC); an electronic circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; a programmable logic controller, a programmable control system such as a processor based control system including a computer based control system, a process controller such as a PID controller, a digital signal processor, or other suitable hardware components that provide the described functionality or provide the above functionality when programmed with software implementing the logic described herein; or a combination of some or all of the above, such as in a system-on-chip. The term software, as used herein, may refer to computer programs, routines, functions, classes, and/or objects and may include firmware, and/or microcode. When it is stated that active noise drive circuit  318  or vibration drive circuit  910  performs a function, it should be understood that active noise drive circuit  318  or vibration drive circuit  910  is configured to do so such as by appropriate software, electronic circuit(s) including discrete and integrated logic, or combination thereof. 
         [0057]    Applying active noise cancellation to the operational noise of a food waste disposer may make it feasible for either the manufacturer or the user themselves to select how loud they would like to the food waste disposer to be when operating. It is possible that the user may want to hear some low level noise from the disposer during operation so that they know it is working. Being able to customize the degree of active noise cancellation, particularly for the user, would make it possible to adjust the noise as activity in the home warrants. On the other hand, the manufacturer could tune the active noise cancellation so that the effectiveness is differentiated by model similar to current product differentiation in the disposer line. Further, masking noise could be introduced along with the active cancellation to mask higher frequency sounds which tend to be more difficult to actively attenuate. Similar to the active noise cancelling effectiveness, the spectral and temporal characteristics of masking noise could be manipulated by the manufacturer to further influence the operator&#39;s perception of the sound. Similarly, an operator selectable option to play music or some other type of sound over the noise of the disposer could be included to enhance the operator&#39;s awareness that the disposer was running and/or to mask the noise of the disposer. 
         [0058]    Characteristics of the food waste disposer operational noise that make it suitable for active noise control are (1) on average the noise is tonal with dominating peaks less than 1000 Hz which is the most physically suitable frequency range for active noise cancellation, (2) the noise is time varying at a rate which is well within the active noise control controller adaptation rate and so can be tracked and cancelled in real time as the food waste disposer operates, and (3) an acoustic or vibration reference signal is available at the noise source which is coherent to the acoustic signal experienced or measured in the desired area of active noise cancellations. 
         [0059]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.