Patent Publication Number: US-9845794-B2

Title: Hydraulically actuated diaphragm pumps

Description:
TECHNICAL FIELD 
     The present disclosure relates, generally, to diaphragm pumps and, more particularly, to hydraulically actuated diaphragm pumps. 
     BACKGROUND 
     Pneumatic diaphragm pumps have been used for pumping one or more fluids. Pneumatic diaphragm pumps generally include at least one pumping chamber having a diaphragm separating a motive fluid chamber for moving a motive fluid and a pump chamber for pumping a working fluid. Compressed air is fed into the motive fluid chamber to expand the diaphragm, which, in turn, causes the working fluid to be pumped through an outlet of the pump chamber. While pneumatic diaphragm pumps utilizing compressed air are effective, they may also be very inefficient and, thus, very costly. 
     SUMMARY 
     According to one aspect, a diaphragm pump may comprise a housing defining a first pumping chamber, a second pumping chamber, and a hydraulic fluid chamber, a first flexible diaphragm separating the first pumping chamber from the hydraulic fluid chamber, a second flexible diaphragm separating the second pumping chamber from the hydraulic fluid chamber, a rod mechanically linking the first flexible diaphragm and the second flexible diaphragm such that an expansion of one of the first and second flexible diaphragms exerts a contraction force on the other of the first and second flexible diaphragms, and a piston disposed within the hydraulic fluid chamber and configured to reciprocate to cause a hydraulic fluid contained within the hydraulic fluid chamber to alternately exert an expansion force on the first and second flexible diaphragms. 
     In some embodiments, the diaphragm pump may further comprise a motor operatively connected to the piston to cause reciprocal movement of the piston. The motor may comprise a rotatable output shaft, an arm having a first end attached to the output shaft, and a roller bearing attached to a second end of the arm opposite the first end. The piston may comprise a cavity receiving the roller bearing, such that rotation of the output shaft causes movement of the roller bearing within the cavity, thereby causing reciprocal movement of the piston. 
     In some embodiments, the diaphragm pump may further comprise a mechanism configured to deactivate the motor upon detection of a stall in the pump. The mechanism may comprise one or more motion sensors configured to sense ends of a stroke of the piston. The mechanism may comprise a motor overcurrent detection circuit configured to measure a current drawn by the motor and to deactivate the motor when the current is greater than a pre-determined level. The mechanism may comprise a clutch disposed between the output shaft of the motor and the piston, the clutch being configured to disengage when a torque between the output shaft and the piston exceeds a mechanically-set threshold. 
     According to another aspect, a diaphragm pump may comprise a housing defining a first working chamber and a second working chamber, a first flexible diaphragm separating the first working chamber into a first pump chamber and a first motive fluid chamber, a second flexible diaphragm separating the second working chamber into a second pump chamber and a second motive fluid chamber, a channel in fluid communication with the first and second motive fluid chambers, a rod mechanically linking the first and second flexible diaphragms, a piston disposed within the channel and configured to reciprocate to cause a hydraulic fluid contained within the channel and the first and second motive fluid chambers to alternately exert an expansion force on the first and second flexible diaphragms, a motor operatively connected to the piston and configured to drive reciprocal movement of the piston, and a clutch operatively connected between an output shaft of the motor and the piston, the clutch being configured to deactivate the motor upon detection of an overload condition. 
     In some embodiments, the rod may be configured to simultaneously contract one of the first and second flexible diaphragms as the other of the first and second flexible diaphragms expands. The motor may further comprise an arm having a first end attached to the output shaft and a roller bearing attached to a second end of the arm opposite the first end. The piston may comprise a cavity receiving the roller bearing, such that rotation of the output shaft causes movement of the roller bearing within the cavity, thereby causing reciprocal movement of the piston. The clutch may be configured to be engaged when a torque between the output shaft and the piston is below a mechanically-set threshold and to be disengaged when the torque between the output shaft and the piston exceeds the mechanically-set threshold. 
     According to yet another aspect, a method of operating a diaphragm pump comprising a housing defining first and second pumping chambers and a hydraulic fluid chamber, a first flexible diaphragm separating the first pumping chamber from the hydraulic fluid chamber, a second flexible diaphragm separating the second pumping chamber from the hydraulic fluid chamber, a rod mechanically linking the first and second diaphragms, a piston disposed within the hydraulic fluid chamber, and a motor operatively connected to the piston is disclosed. The method may comprise activating the motor to drive reciprocal movement of the piston, the reciprocal movement of the piston causing alternating expansion of the first and second flexible diaphragms, the rod causing alternating contraction of the first and second flexible diaphragms, and deactivating the motor upon detection of a stall condition within the pump. 
     In some embodiments, deactivating the motor may comprise disengaging a clutch operatively connected between an output shaft of the motor and the piston when a torque between the output shaft and the piston exceeds a mechanically-set threshold. Deactivating the motor may comprise measuring a current drawn by the motor and deactivating the motor if the measured current is greater than a pre-determined level. Deactivating the motor may comprise sensing motion of the piston near an end of a stroke of the piston and deactivating the motor if motion of the piston has not been detected for a pre-determined period of time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The concepts described in the present disclosure are illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements. 
         FIG. 1  is a front perspective view of at least one embodiment of a double diaphragm pump; 
         FIG. 2  is a schematic cross-sectional view of a prior art pump that may be embodied within the pump housing of  FIG. 1 ; 
         FIG. 3  is a schematic cross-sectional view of an embodiment of a hydraulically actuated pump that may be embodied within the pump housing of  FIG. 1 ; 
         FIG. 4  is a schematic view of an exemplary hydraulic drive mechanism in the form of a motor-piston drive mechanism that may be used with the pump of  FIG. 3 ; 
         FIG. 5  is an elevational view of an exemplary hydraulic drive mechanism that may be used with the pump of  FIG. 3 , wherein an overload clutch is depicted in an engaged condition; 
         FIG. 6  is an elevational view of the hydraulic drive mechanism of  FIG. 5  with the overload clutch depicted in a disengaged or separated condition; and 
         FIG. 7  is a schematic cross-sectional view of an additional embodiment of a hydraulically actuated pump that may be embodied within the pump housing of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. 
     Referring now to  FIG. 1 , a diaphragm pump  10  is shown. The pump  10  of  FIG. 1  is illustratively embodied in  FIG. 2  as a pneumatically actuated double-diaphragm pump. It is contemplated that, in other embodiments, the pump  10  may be embodied as any other type of diaphragm pump. In the illustrative embodiment, the pump  10  has a housing  12  that defines a first working or pumping chamber  14  and a second working or pumping chamber  16 . 
     In an illustrative prior art embodiment, as seen in  FIG. 2 , the housing  12  is comprised of three sections coupled together by fasteners. The first and second working chambers  14 ,  16  of the pump  10  are each divided by respective first and second flexible diaphragms  18 ,  20  into respective first and second pump chambers  22 ,  24  and first and second motive fluid chambers  26 ,  28 . The diaphragms  18 ,  20  are interconnected by a rod or shaft  30 , such that when the diaphragm  18  is moved to increase the volume of the associated pump chamber  22 , the other diaphragm  20  is simultaneously moved to decrease the volume of the associated pump chamber  24 , and vice versa. 
     The shaft  30  illustrated in  FIG. 2  is a reciprocating diaphragm link rod having a fixed length, such that the position of the shaft  30  in the pump  10  is indicative of the position of the diaphragms  18 ,  20 . The shaft  30  and diaphragms  18 ,  20  move back and forth a fixed distance that defines a stroke. The fixed distance is determined by the geometry of the pump  10 , the shaft  30 , the diaphragms  18 ,  20 , and other components of the pump  10  (e.g., the diaphragm washers). A stroke is defined as the travel path of the shaft  30  between first and second end-of-stroke positions. Movement of the shaft  30  from one end-of-stroke position to the other end-of-stroke position and back defines a cycle of operation of the shaft  30  (i.e., a cycle includes two consecutive strokes). 
     The pump  10  includes one or more inlets  32  for the supply of a motive fluid (e.g., compressed air, or another pressurized gas) to the first and second motive fluid chambers  26 ,  28  to drive reciprocation of the diaphragms  18 ,  20  and the shaft  30 . The pump  10  may be alternately connected to the inlets  32 . Alternatively, one or more valves  34  may be connected to one or more inlets for alternately supplying the motive fluid to the first and second motive fluid chambers  26 ,  28 . When the valve  34  supplies motive fluid to the motive fluid chamber  26 , the valve  34  places an exhaust assembly  36  in communication with the other motive fluid chamber  28  to permit motive fluid to be expelled therefrom. Conversely, when the valve  34  supplies motive fluid to the motive fluid chamber  28 , the valve  34  places the motive fluid chamber  26  in communication with the exhaust assembly  36 . In the illustrative embodiment of the pump  10 , movement of the valve  34  between these positions is controlled by a solenoid valve. As such, by controlling movement of the valve  34 , the solenoid valve of the pump  10  controls the supply of the motive fluid to the first and second motive fluid chambers  26 ,  28 . 
     During operation of the pump  10 , as the shaft  30  and the diaphragms  18 ,  20  reciprocate, the first and second pump chambers  22 ,  24  alternately expand and contract to create respective low and high pressure within the respective first and second pump chambers  22 ,  24 . The pump chambers  22 ,  24  each communicate with an inlet manifold  38 ,  40  that may be connected to a source of fluid  41 ,  43 , respectively, to be pumped and also each communicate with an outlet manifold, or fluid outlet,  42 ,  44  that may be connected to a receptacle for the fluid  41 ,  43  being pumped. Check valves  46 ,  48  ensure that the fluid  41 ,  43  being pumped moves only from the inlet manifold  38 ,  40  toward the outlet manifold  42 ,  44  when an appropriate amount of vacuum pressure is stored within the respective motive fluid chamber  26 ,  28 . Referring to  FIG. 2 , the check valves  46 ,  48  are shown in an upper position when fluid  41 ,  43  within the pump chambers  22 ,  24  is to be pumped from the respective chamber and in a lower position when fluid  41 ,  43  within the pump chambers is to remain within the respective chamber. When the pump chamber  22  expands, the resulting negative pressure draws fluid  41  from the inlet manifold  38  into the pump chamber  22 . Simultaneously, the other pump chamber  24  contracts, which creates positive pressure to force fluid  43  contained therein into the outlet manifold  44 . Subsequently, as the shaft  30  and the diaphragms  18 ,  20  move in the opposite direction, the pump chamber  22  will contract and the pump chamber  24  will expand (forcing fluid  41  contained in the pump chamber  22  into the outlet manifold  42  and drawing fluid  43  from the inlet manifold  40  into the pump chamber  24 ). 
     Referring now to  FIG. 3 , an illustrative embodiment of a hydraulically actuated pump  100  is depicted. In the illustrative embodiment, the pump  100  has a housing, for example, similar to the housing  12  seen in  FIG. 1 . The housing of the pump  100  defines a first working or pumping chamber  114  and a second working or pumping chamber  116 . The first and second working chambers  114 ,  116  of the pump  100  are each divided by respective first and second flexible diaphragms  118 ,  120  into respective first and second pump chambers  122 ,  124  and first and second motive fluid chambers  126 ,  128 . The diaphragms  118 ,  120  are interconnected by a rod or shaft  130 , such that when the diaphragm  118  is moved to increase the volume of the associated pump chamber  122 , the other diaphragm  120  is simultaneously moved to decrease the volume of the associated pump chamber  124 , and vice versa. 
     The shaft  130  illustrated in  FIG. 3  is a reciprocating diaphragm link rod having a fixed length, such that the position of the shaft  30  in the pump  10  is indicative of the position of the diaphragms  118 ,  120 . The shaft  130  may be attached to the diaphragms  118 ,  120  by plastic washers or in any other suitable manner. The shaft  130  and diaphragms  118 ,  120  move back and forth a fixed distance that defines a stroke. The fixed distance is determined by the geometry of the pump  100 , the shaft  130 , the diaphragms  118 ,  120 , and other components of the pump  100  (e.g., the diaphragm washers). A stroke is defined as the travel path of the shaft  130  between first and second end-of-stroke positions. Movement of the shaft  130  from one end-of-stroke position to the other end-of-stroke position and back defines a cycle of operation of the shaft  130  (i.e., a cycle includes two consecutive strokes). 
     Referring to  FIG. 3 , the shaft  130  extends through the first and second motive fluid chambers  126 ,  128  and through a channel  160 , for example a cylindrical channel, extending between and in fluid communication with the motive fluid chambers  126 ,  128 . An electric motor  162 , for example an alternating current or direct current motor, is operatively connected to the shaft  130  to move the shaft  130  back and forth (i.e., left and right, as seen in  FIG. 3 ). As seen in  FIG. 4 , the electric motor  162  may include an output shaft  164  that may be rotated, for example, in a counterclockwise direction. An arm  166  extends outwardly from the output shaft  164  and includes a roller bearing  168  on an end thereof. The roller bearing  168  is accepted and rides within a cavity  170  of a piston  172 , wherein the cavity  170  has a longitudinal extent that may be generally perpendicular to movement of the piston  172 . 
     Prior to operation of the pump  100 , an amount of motive fluid F 1  in the motive fluid chamber  126  and a portion of the channel  160  in fluid communication with the motive fluid chamber  126  may be generally the same as an amount of motive fluid F 2  in the motive fluid chamber  128  and a portion of the channel  160  in fluid communication with the motive fluid chamber  128 . 
     As the electric motor  162  rotates an output shaft  164 , the arm  166  and the roller bearing  168  rotate with the output shaft  164 . The roller bearing  168  moves back and forth along the cavity  170  of a piston  172  to accommodate the rotation of the arm  166 . When the roller bearing  168  reaches a first edge  180  of the cavity  170 , and the arm  166  continues to rotate, the piston  172  is moved along the channel  160  toward the chamber  114 . Likewise, as the roller bearing  168  reaches a second edge  182  of the cavity  170 , and the arm  166  continues to rotate, the piston  172  is moved along the channel  160  toward the chamber  116 . The piston  172  may be positioned within the channel  160  such that the motive fluids F 1 , F 2  may be prevented from passing the piston  172 . In an illustrative embodiment, a seal may be formed around one or more portions of the piston  172  to prevent movement of motive fluid F 1 , F 2  past the piston  172 , while still allowing movement of the piston  172 . As the piston moves, the overall space in which the motive fluids F 1 , F 2  are held increases and decreases, thereby causing alternating low and high pressure against the flexible diaphragms  118 ,  120 , which, in turn, causes the flexible diaphragms  118 ,  120  to contract and expand. 
     As seen in  FIG. 3 , each of the pump chambers  122 ,  124  communicates with an inlet manifold  200 ,  202  that may be connected to a source of fluid  204 ,  206  to be pumped. Each of the pump chambers  122 ,  124  also communicates with an outlet manifold, or fluid outlet  208 ,  210 . Check valves  212 ,  214  ensure that the fluid  204 ,  206  being pumped moves only from the inlet manifold  200 ,  202  toward the outlet manifold  208 ,  210  when an appropriate amount of vacuum pressure is stored within the respective motive fluid chamber  126 ,  128 . Referring to  FIG. 3 , the check valves  212 ,  214  are shown in an upper position when fluid  204 ,  206  within the pump chambers  122 ,  124  is to be pumped from the respective chamber and in a lower position when fluid  204 ,  206  within the pump chambers  122 ,  124  is to remain within the respective chamber. When the pump chamber  122  expands, the resulting negative pressure draws fluid  204  from the inlet manifold  200  into the pump chamber  122 . Simultaneously, the other pump chamber  124  contracts, which creates positive pressure to force fluid  206  contained therein into the outlet manifold  210 . Subsequently, as the shaft  130  and the diaphragms  118 ,  120  move in the opposite direction, the pump chamber  122  will contract and the pump chamber  124  will expand (forcing fluid  204  contained in the pump chamber  122  into the outlet manifold  208  and drawing fluid  206  from the respective inlet manifold  202  into the pump chamber  124 ). 
     A mechanism for overload or stall protection may be implemented within the pump  100  of  FIG. 3  to protect the electric motor  162  from a potentially damaging condition wherein a main hydraulic pump output is blocked or does not permit free operation. In an illustrative embodiment, for example should the piston  172  get stuck and stop reciprocating, the motor  162  would generally continue providing rotational energy to the output shaft  164 , thereby creating the potential for damage to the motor  162 . The methods of stall protection disclosed herein may halt operation of the motor  162  in the presence of potentially damaging conditions. 
     In an illustrative embodiment of stall protection, as seen in  FIGS. 5 and 6 , an overload clutch  220  may be positioned between the output shaft  164  of the electric motor  162  and the piston  172 . The overload clutch  220  may generally include first and second discs  222 ,  224  attached to the rotatable output shaft  164  of the motor  162  and a shaft  225  extending between the second disc  224  and the arm  166 , respectively. First and second clutch gears  226 ,  228  are attached to the output shaft  164  and the shaft  225 , respectively, and are biased into engagement by springs  230 ,  232  disposed between the clutch gears  226 ,  228  and the discs  222 ,  224 . When the clutch gears  226 ,  228  are engaged, as described in detail above, the output shaft  164  rotates the gears  226 ,  228 , as seen in  FIG. 5 , which transfer rotational energy to the shaft  225 , the arm  166  and the roller bearing  168 , which causes reciprocating movement of the piston  172 . If the piston  172  is not moving freely (or other issues are present with the pump  100  and/or piston  172 ), the second clutch gear  228  remains stationary, as seen in  FIG. 6 . When a torque between the output shaft  164  of the motor  162  and the piston  172  is below a mechanically-set threshold of the overload clutch  220 , no relative movement between the clutch gears  226 ,  228  occurs. If the torque between the output shaft  164  and the piston  172  exceeds the mechanically-set threshold of the overload clutch  220 , relative movement between the clutch gears  226 ,  228  occurs, thereby causing the clutch gears  226 ,  228  to separate. Separation of the clutch gears  226 ,  228  may be used to trigger a switch  234  to deactivate the motor  162  and/or other components of the pump  100 . Alternatively, separation of the clutch gears  226 ,  228  may trigger any other suitable event, condition, or alarm. 
     In a further illustrative embodiment, as shown in  FIG. 7 , the stall protection may be implanted within circuitry as a motor overcurrent detection circuit  400  that may deactivate the motor  162  when a measured current drawn by the electric motor  162  is greater than a pre-determined safe level. 
     In a still further illustrative embodiment of stall protection, a position of the piston  172  may be monitored by motion sensors  402 ,  404  (e.g., Hall effect sensors) mounted at or near an end of each piston stroke. If no signal is received from a sensor within a particular time interval (e.g., due to a blockage in the system, breakage of the connection between the motor  162  and the piston  172 , etc.), the motor  162  may be deactivated. 
     In illustrative embodiments, the pump  100  may include one or more mechanisms for compensating for leakage within the pump  100 , for example, from the motive fluid chambers  126 ,  128 . At times, motive fluid F 1  or F 2  may escape from the pump  100 , which can create issues with operation of the pump  100 . It is therefore desirable to replace lost motive fluid F 1 , F 2 . Referring to  FIG. 3 , an illustrative embodiment of a leakage compensation mechanism is depicted as having two ports  300 ,  302  within an upper wall  304  of the channel  160 . Each port  300 ,  302  may be in fluid communication with a respective motive fluid reservoir  306 ,  308  containing motive fluid. The motive fluid reservoirs  306 ,  308  may be positioned adjacent the upper wall  304  of the channel  160  and may be of any size and/or shape. As the piston  172  moves back and forth along the channel  160 , the piston  172  may alternatingly block and unblock the ports  300 ,  302 . More specifically, as the piston  172  reaches the end of a stroke, for example in its right-most position in which no pressure is exerted on the motive fluid F 1 , as seen in  FIG. 3 , the piston  172  would no longer block the port  300  (and would block the port  302 ). Similarly, as the piston  172  reaches its left-most position in which no pressure is exerted on the motive fluid F 2 , the piston  172  would no longer block the port  302  (and would block the port  300 ). In this manner, the ports  300 ,  302  would only be unblocked at the end of a stroke. When the ports  300 ,  302  are unblocked, if bubbles or open space are present within the respective motive fluid chamber  126 ,  128 , the motive fluid within the respective motive fluid reservoir would be pumped into the respective motive fluid chamber  126 ,  128  to replace the empty space or bubbles (until the respective motive fluid chamber  126 ,  128  is full). 
     While a single portion  300 ,  302  is shown in conjunction with each motive fluid chamber  126 ,  128 , multiple fluid ports may alternatively be used. Still further, while two motive fluid reservoirs  306 ,  308  are depicted, a single reservoir may alternatively communicate with both (or all, if more than two total) ports  300 ,  302 . In any of the embodiments described herein, the rod  130  may be positioned toward the inlet manifolds  200 ,  202  or toward the outlet manifolds  208 ,  210 . In alternative embodiments, any other suitable mechanism or method for compensating for leakage may be additionally or alternatively used within the pump  100 . 
     While certain illustrative embodiments have been described in detail in the figures and the foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. There are a plurality of advantages of the present disclosure arising from the various features of the apparatus, systems, and methods described herein. It will be noted that alternative embodiments of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the apparatus, systems, and methods that incorporate one or more of the features of the present disclosure.