Abstract:
Noise control systems and methods for brakes and clutches are disclosed, in which voltage profiles comprise at least one or two step profiles and at least one ramp profile. The voltage profiles are selectively applied to at least one of a stationary member or rotary member of the brake or clutch in order to decrease noise during operation thereof. Such systems and methods can be adapted for use in medical imaging equipment, particularly to decrease the noise of brakes and clutches commonly associated therewith.

Description:
FIELD OF INVENTION  
       [0001]     In general, the inventive arrangements relate to brakes and clutches, and more specifically, to systems and methods for reducing or eliminating audible noise in brakes and clutches during brake and clutch operations, such as, by way of illustrative, exemplary, representative, and non-limiting example, the types of brake and clutch operations provided in driving or controlling medical imaging equipment and the like.  
       BACKGROUND OF INVENTION  
       [0002]     For illustrative, exemplary, representative, and non-limiting purposes, a preferred embodiment of the inventive arrangements will be described in terms of medical imaging equipment. However, the inventive arrangements are not limited in this regard.  
         [0003]     For example, common medical imaging equipment includes radiology, vascular imaging, fluoroscopy, mammography, X-ray, computed tomography (CT), nuclear medicine (NM), positron emission tomography (PET), magnetic resonance imaging (MRI), and ultrasound apparatuses, and the like. Such equipment commonly includes an electromechanical device for driving or controlling movement of a patient positioner, such as a patient table, gantry comprising a pivot arm or c-arm, or the like. Such devices may also include an electromechanical brake or electromechanical clutch, which permit equipment operators to control movement of such patient positioners.  
         [0004]     For example, and referring now to  FIG. 1 , a common electromechanical brake or brake system  10  comprises at least one stationary member  20  coupled to at least one rotary member  30 . Commonly, the stationary member  20  is further coupled to an electromagnet  22 , which is coupled to a brake coil  24 , which can be selectively energized or de-energized by a power supply  26 . The electromagnet  22  applies an electromagnetic force B to the stationary member  20 . Likewise, the rotary member  30  is releasably coupled to a base plate  32 , which is coupled to a brake spring  34 . The brake spring  34  applies a spring force F to the rotary member  30 .  
         [0005]     Commonly, when the brakes  10  are applied, the power supply  26  de-energizes the brake coil  24 , which allows the brake coil  24  to magnetize the electromagnet  22 . In this condition, the magnetic force B overcomes or is allowed to overcome the spring force F, causing the stationary member  20  and rotary member  30  to draw or be drawn together. This allows the stationary member  20  and rotary member  30  to be brought together, thereby preventing the rotary member  30  from moving freely or rotating relative to the stationary member  20 . Not surprisingly, a significant amount of noise is generated as the stationary member  20  and rotary member  30  draw or are drawn together and strike. Likewise, when the brakes  10  are released or not being applied, the power supply  26  energizes the brake coil  24 , which allows the brake coil  24  to demagnetize the electromagnet  22 . In this condition, the spring force F overcomes or is allowed to overcome the electromagnetic force B, causing the rotary member  30  and base plate  32  to draw or be drawn together. This allows the stationary member  20  and rotary member  30  to separate or move apart, thereby allowing the rotary member  30  to move freely or rotate relative to the stationary member  20 . Not surprisingly, a significant amount of noise is generated as the rotary member  30  and base plate  32  draw or are drawn together and strike.  
         [0006]     As described, a voltage, such as a DC supply voltage from the power supply  26 , preferably energizes or de-energizes the brake coil  24 . Also as described, since each of the stationary member  20 , rotary member  30 , and base plate  32  are made of traditionally metal or metallic materials, the metal-to-metal contact generates the described noise, which can cause a disturbance or inconvenience to applicable parties, including, for example, equipment operators utilizing the medical imaging equipment or a patient being examined. And in an emergency brake operation, noise levels can climb even disturbingly higher.  
         [0007]     One traditional solution to decreasing unwanted brake noise in conventional brake or brake systems  10  includes placing a ring damper around a brake drum, such that relative motion and controlled slippage are permitted between the ring damper and the brake drum whenever the ring damper vibrates during brake apply or release operations. However, this solution requires adding additional hardware to the brake or brake system  10 , which can be expensive and bulky.  
         [0008]     Another traditional solution includes utilizing a soft start controller, which the power supply  26  can use to implement a voltage ramp profile to energize the brake coil  24 . However, for a typical ramp of 0 to 24 volts with a slope of IV/500 mS, a typical latency time can exceed approximately 12 seconds.  
         [0009]     Moreover, none of the traditional solutions appear to control noise generated during brake and clutch operations within medical imaging equipment, wherein applicable systems and methods substantially decrease metal-to-metal contact between stationary members  20 , rotary members  32 , and base plates  34 , or work independently of supply voltage variations, or provide for silent and smooth brake and clutch operations over wide ranges of power applied from power supplies  26 .  
         [0010]     And similar to the described brake and brake operations, similar operational characteristics also occur with clutch and clutch operations and the like.  
       SUMMARY OF INVENTION  
       [0011]     In one embodiment, a noise control method for a brake or clutch comprises coupling a stationary member to a rotary member of a brake or clutch, wherein attraction or repulsion between the stationary member and rotary member results from an apply or release operation of the brake or clutch, and applying a voltage profile to at least one of the stationary member or rotary member during operation of the brake or clutch in order to move the stationary member and rotating member relative to one another at one or more desired speeds in order to decrease noise during operation of the brake or clutch.  
         [0012]     In another embodiment, a noise control method for a brake or clutch comprises generating a voltage profile having at least one step profile and at least one ramp profile; and applying the voltage profile to at least one of a stationary member or rotary member of a brake or clutch in order to decrease noise during operation of the brake or clutch.  
         [0013]     In yet another embodiment, a noise controller for a brake or clutch comprises a stationary member coupled to a rotary member of a brake or clutch, wherein attraction or repulsion between the stationary member and rotary member results from an apply or release operation of the brake or clutch, and a voltage generator operatively coupled to at least one of the stationary member or rotary member, wherein the voltage generator generates a voltage profile comprising at least one step profile and at least one ramp profile that are selectively applied to at least one of the stationary member and rotating member in order to reduce noise during operation of the brake or clutch.  
         [0014]     And in yet another embodiment, medical equipment comprises a stationary member coupled to a rotary member of a brake or clutch of the medical equipment, wherein attraction or repulsion between the stationary member and rotary member results from an apply or release operation of the brake or clutch, and a voltage generator operatively coupled to at least one of the stationary member or rotary member, wherein the voltage generator generates a voltage profile comprising at least one step profile and at least one ramp profile that are selectively applied to at least one of the stationary member and rotating member in order to reduce noise during operation of the brake or clutch. 
     
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0015]     A clear conception of the advantages and features constituting inventive arrangements, and of various construction and operational aspects of typical mechanisms provided by such arrangements, are readily apparent by referring to the following illustrative, exemplary, representative, and non-limiting figures, which form an integral part of this specification, in which like numerals generally designate the same elements in the several views, and in which:  
         [0016]      FIG. 1  depicts a high-level block diagram of an electromechanical brake or brake system;  
         [0017]      FIG. 2  depicts a high-level block implementation diagram of systems and methods for reducing or eliminating audible noise in brakes and clutches during brake and clutch operations; and  
         [0018]      FIG. 3  depicts a voltage profile for controlling a brake or clutch. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]     Various embodiments of the inventive arrangements provide systems and methods for reducing or eliminating audible noise in brakes and clutches during brake and clutch operations. However, the inventive arrangements are not limited in this regard, and they may also be implemented in connection with other applications as well.  
         [0020]     Referring now to  FIG. 2 , a voltage controller  40  for a brake or clutch  42  is depicted. More specifically, the voltage controller  40  includes a power supply  26  that is operatively connected to i) a drive unit  44 , and ii) a voltage profile generator  46  through a voltage supply measurement circuit  48 .  
         [0021]     Preferably, the voltage profile generator  46  is also operatively coupled to a Pulse Width Modulation (“PWM”) generator  50 , which drives the brake or clutch  42  through the drive unit  44 , which is operatively coupled between the PWM generator  50  and brake or clutch  42 . Alternatively, the voltage profile generator  46  may also include a servo controller (not shown), perhaps instead of the PWM generator  50 , for driving the brake or clutch  42  through the drive unit  44 . Regardless, the drive unit  44  preferably drives the brake or clutch  42  according to a gradually varying voltage profile, such as that depicted in  FIG. 3 .  
         [0022]     Preferably, the voltage profile generator  46  generates a dc voltage pulse of desired magnitude for a desired period of time. The PWM generator  50  is, in turn, configured for modulating the dc voltage pulse from the voltage profile generator  46 , and, in turn, generating the varying voltage profile depicted in  FIG. 3 , ultimately supplying desired supply voltage signals that drive the brake or clutch  42  through the drive unit  44 . And preferably, the voltage supply measurement circuit  48  measures the voltage from the power supply  26  that is ultimately supplied to the brake or clutch  42  through the drive unit  44 , and the drive unit  44  preferably includes (although not shown) i) a switching device, such as a MOSFET, relay, transistor, etc., and ii) a switching driver for driving the brake or clutch  42  as desired.  
         [0023]     As previously described, release and apply operations of the brake or clutch  42  cause the magnetic attraction or repulsion of the stationary member  20  and rotary member  30 . As will be further described, the voltage of a gradually varying profile, according to the inventive arrangements, reduces or substantially reduces the magnetic attraction and repulsion speed between the stationary member  20  and rotary member  30 . This, in turn, substantially decreases the metal-to-metal contact, and noise, between the stationary member  20 , rotary member  30 , and base plate  32 . Since the energy of the rotating member  30  can be substantially reduced and controlled, noise generated during the attraction and repulsion of the stationary member  20 , rotary member  30 , and base plate  32  can also be reduced or substantially reduced.  
         [0024]     Referring now to  FIG. 3 , a voltage profile  52  for controlling the brake or clutch  42  is depicted. More specifically, time is plotted on an x-axis against a DC voltage plotted on a y-axis, yielding a desired voltage profile  52  for energizing the brake or clutch  42 . Alternatively, another current profile  52 ′ (not shown) could also be readily substituted for the voltage profile  52  with equal or substantially equal effect. Regardless, the voltage profile  52  is depicted for convenience, ultimately controlling operation of the brake or clutch  42 .  
         [0025]     More specifically,  FIG. 3  depicts a preferred voltage profile  52  for time-varying the voltage supplied to the brake or clutch  42 . Accordingly, the voltage profile  52 , as depicted, comprises at least one step profile  54 , 58  and at least one ramp profile  56  for both a brake release operation  60  and a brake apply operation  62 , both of which can reduce or substantially reduce noise during operation of the brake or clutch  42 , as will now be illustrated by the following example:  
         [0026]     In the illustrative, exemplary, representative, and non-limiting example shown in  FIG. 3 , during a brake release operation  60 , for example, for a dc pulse of 0-24 volts, a first step profile  54   a  is generated from 0 volts up to approximately 18 volts upstream. Then, a ramp-up (or first ramp) profile  56   a  is initiated at the approximate 18 volts and terminated at approximately 19 volts. And finally, a second step profile  58   a  is then applied from the approximate 19 volts up to approximately 24 volts upstream. Likewise, during a brake apply operation  62 , for example, again for the same dc pulse of 0-24 volts, a first step profile  54   b  is generated from 24 volts down to approximately 8 volts downstream. Then, a ramp-down (or second ramp) profile  56   b  is initiated at the approximate 8 volts and terminated at approximately 7 volts. And finally, a second step profile  58   b  is then applied from the approximate 7 volts down to 0 volts downstream.  
         [0027]     It should be noted that the magnitudes of the dc voltages and the duration of the ramp  54 ,  58  and step profiles  56  can be appropriately varied depending upon the force required or desired to operate the brake or clutch  42 . For example, in the example shown in  FIG. 3 , the duration of each of the ramp profiles  56  is about 500 mS.  
         [0028]     Accordingly, by implementing varying voltage profiles  52  according to the inventive arrangements via the voltage controller  40 , noise during operation of the brake or clutch  42  can be reduced or substantially reduced. In addition, decreasing the metal-to-metal contact between the stationary member  20 , rotary member  30 , and base plate  32  can also reduce or substantially reduce the wear-and-tear on these components, thereby advantageously extending the life of the brake or clutch  42 .  
         [0029]     Regardless, in a preferred embodiment, the voltage supplied to the drive unit  44  is measured continuously, and the start and stop of the ramp profiles  56  within a specified voltage range can be adjusted in response to variations in supply voltages. Thus, noise generated during operation of the brake or clutch  42  can be significantly controlled even in the face of widely fluctuating supply voltages from a given power source  26 .  
         [0030]     It should be readily apparent that this specification describes exemplary, representative, and non-limiting embodiments of the inventive arrangements. Accordingly, the scope of the inventive arrangements are not limited to any of these embodiments. Rather, various details and features of the embodiments were disclosed as required. Thus, many changes and modifications-as readily apparent to those skilled in the art—are within the scope of the inventive arrangements without departing from the spirit hereof, and the inventive arrangements include the same. Accordingly, to apprise the public of the scope and spirit of the inventive arrangements, the following claims are made: