Abstract:
An exemplary magnetically-driven fluid pump includes a magnet housing (“cup”) that enables one or more sensors to be in indirect (“non-wetted”) contact with the pumped fluid while avoiding the static seals normally required with sensors that are mounted to a fluid conduit or chamber and extend into the fluid pathway. Sensors may be used for monitoring the fluid or for feedback control of the pump. By coupling sensors directly to electronic circuits that control the pump, the number of wires located outside the motor housing is minimized, making the assembly more rugged. This is particularly advantageous in hazardous environments or submerged applications. Pumps and hydraulic systems disclosed exhibit fewer leaks under more aggressive pumping conditions and while providing improved pump performance, compared to conventional pumps and systems.

Description:
RELATED APPLICATION 
       [0001]    This patent application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/396,715, filed on Jun. 1, 2010, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    This disclosure pertains to, inter alia, various types of pumps that are magnetically driven. More specifically it pertains to such pumps in which a rotary or rotary-reciprocating element, such as a pump gear, is connected to a driven magnet housed in a magnet housing (“magnet cup”) in which the magnet is wetted by the fluid being pumped by the pump. 
       BACKGROUND 
       [0003]    Conventional hydraulic systems often include one or more pumps for urging fluid flow. Many such systems also include sensors or indicators of any of various parameters such as pressure, temperature, conductivity, etc., of the fluid flowing in the system. Conventional indicators include Bourdon gauges, ball-flowmeters, analog thermometers, and the like that directly indicate the respective parameter. A “sensor” usually includes a transducer or the like that converts the parameter being sensed (e.g., pressure or temperature) into a corresponding signal (e.g., an electronic or optical signal). The sensor usually also includes an electronic circuit that receives data directly from the transducer and processes the data for use by other electronics as required for, e.g., providing a measure of the parameter or for use in control circuits. The measurement can be used, for example, for a display of the parameter (e.g., LED display). An example control circuit includes a controller connected and configured to perform feedback control or other control of a motor or other actuator powering a pump. 
         [0004]    In hydraulic systems including a pump, the pump is typically a discrete stand-alone component, by which is meant that the pump is manufactured and sold separately, from other components, to original equipment manufacturers (OEMs) for incorporation into the OEM&#39;s own system, along with other components, fluid conduits, and the like. Similarly, sensors and indicators are also usually discrete components, configured and sold for use by OEMs in any of various applications. This arrangement works fine for most hydraulic circuits, particularly those in which space is not a constraining factor. However, connecting a conventional discrete component into a hydraulic circuit typically requires some kind of static seal. For permanent applications, the components can be welded into place. While usually providing an effective static seal, a component welded into place is extremely difficult or impossible to remove. For many if not most applications, static seal(s) are configured to allow a component to be removed from the system from time to time. An exemplary static seal for this purpose is an elastomeric O-ring, ring seal, gasket, or the like. Unfortunately, these and analogous types of static seals exhibit an increased probability of leaks. Leakage risk can be a serious problem in submersible systems, systems handling hazardous fluids, and systems that must operate under severe conditions or that must operate trouble-free for extremely long periods of time. 
         [0005]    Certain applications of hydraulic circuits have demanded that components thereof, such as pumps, indicators, sensors, conduits, and the like, be miniaturized as much as possible. Other applications have demanded that components be ruggedized to a high degree. Sometimes both miniaturization and ruggedness must be achieved simultaneously. Unfortunately, increased miniaturization often works against achieving simultaneously better ruggedization. This is not only true for hydraulic systems in general but also for pumps and other components used in such systems. 
         [0006]    Striving to reduce size of and/or to ruggedize a hydraulic system can substantially increase the difficulty of using certain discrete components such as pumps and sensors. One challenge involves the difficulty of establishing and maintaining adequate seals, such as static seals isolating the interior of a pump housing from the exterior environment or sealing around a sensor extending from outside into the hydraulic flow path. Another challenge arises from placing and connecting the components much closer together in the system. For example, placing a conventional stand-alone pressure sensor at the inlet or outlet of a miniaturized pump can result in a contorted arrangement that occupies too much space and in which the component is essentially shoe-horned into its location. These arrangements can excessively stress the components and/or their respective housings, compromise seals, and reduce the overall reliability and/or operational life of the components. In fact, requirements of small size and critical sealing can actually preclude the use of conventional fluidic sensors in a hydraulic system. 
       SUMMARY 
       [0007]    Pump systems described herein were developed in the course of researching possible improvements in gear pumps used for specific applications requiring miniaturization and improved ruggedness. Specifically, including one or more sensors as part of the physical pressure barrier (“housing”) of the pump provides much smaller pump-sensor combinations while mitigating the effects of any additional potential leaks by eliminating additional hydraulic connections. 
         [0008]    For magnetically actuating a rotary pumping member (such as a combination of a driving gear and a driven gear in a gear pump), the rotary pumping member is coupled to a driven magnet configured to rotate on a longitudinal axis when driven by a magnet driver. The driven magnet is sealingly housed in a magnet housing (“magnet cup”) that allows the magnet to be bathed by the pumped fluid and isolated from the external environment as the magnet is being driven. This maintains the location of driven parts of the pump within the fluid path and avoids having to use a leak-prone dynamic seal. The ability to isolate the rotor environment from the stator environment is a primary advantage of magnetically-driven pumps. 
         [0009]    Adding sensors to a magnetically-driven pump generally poses a challenge regarding how to deal with electrical connections between the sensor and the electronics that either control operation of the pump (for a feedback control-type sensor), or that store and/or communicate data (for a fluid monitoring-type sensor). Some fluidic sensors that use wired electrical connections are designed so that the wires must pass through a hole (“through-hole”) in the fluid containment wall, thus requiring a seal to prevent fluid from contacting and possibly damaging the electronics. Addition of through-holes and seals tends to make a pump less robust because each wire that enters a motor housing adds a potential leak point where moisture or environmental contaminants can gain access to the motor electronics. The incorporation of one or more sensor transducers in the magnet cup eliminates the need to use discrete component(s) to provide the sensor function(s), thereby eliminating static seal(s) that otherwise would be required. Certain embodiments of magnet cups disclosed herein enable one or more sensors to be in indirect contact with the pumped fluid while avoiding the static seals normally required with sensors that are mounted to a fluid conduit or chamber and extend into the fluid pathway. 
         [0010]    In addition, the volume of space that otherwise would be occupied by housing(s) of the stand-alone component(s) is reduced, resulting in a substantially more compact assembly. By incorporating sensor electronics on a printed circuit board mounted to the outside of the distal-end wall of the magnet cup, for example (with the sensor transducer being mounted to the circuit board and sensing its respective parameter through the wall of the magnet cup), the assemblies are made more compact and more reliable. In this way, the sensor electronics can be coupled directly, with minimal or no external wiring, to motor-control electronics located, for example, on a printed circuit board situated inside a housing containing a magnet-driving stator. By incorporating the sensor(s) in the wall of the magnet cup, because fewer wires are located outside the motor housing, the entire pump assembly is more rugged than conventional pump systems. This is particularly advantageous in hazardous environments or submerged applications. 
         [0011]    Although the exemplary embodiments shown herein are gear pumps, pumping systems consistent with the disclosed sensing devices are not limited to gear pumps. Rather, they include any of various types of pumps having at least one movable pump element contained in a housing and coupled to a permanent magnet that is driven by magnetic forces that originate outside the housing and are directed at the magnet through walls of the housing. The magnet is normally contained in a portion of the housing called a magnet housing or magnet cup. In pumps in which the movable element is a rotary element, the magnet and magnet cup are configured so that the magnet, when placed in a rotating magnetic field, rotates in the magnet cup about a longitudinal magnet axis. To such end the driven magnet usually has a substantially cylindrical shape and the magnet cup has a substantially hollow cylindrical (can-like) configuration that contains the driven magnet. The driven magnet can be driven by a driving magnet coupled to the armature of a motor, or by a driving stator located outside the magnet cup. Lines of magnetic force produced by the driving magnet or by the stator pass through the wall of the magnet cup and inductively couple to the driven magnet. During running of the pump, these lines of magnetic force are directed so as to urge rotation of the driven magnet about its axis, which causes rotation of the rotary pump element. In a gear pump, the rotary pump element is termed a “driving gear” that is interdigitated with a corresponding driven gear. As the driving gear rotates, it causes corresponding contra-rotation of the driven gear. The combined gear rotations produce a pumping force. The gear pump can be, for example, what is conventionally known as a “cavity style” or can include, for example, a “suction shoe,” or can be a hybrid of these. 
         [0012]    Another type of pump involving a movable pump element coupled to a driven magnet is a piston pump. In some configurations of piston pumps, the piston undergoes both rotary and linearly reciprocating motion as driven magnetically. Other exemplary types of pumps include centrifugal pumps, lobe pumps, or pumps that have a pressure-compliant member inside the housing. 
         [0013]    As noted above, the pump housing constitutes the physical pressure barrier of the pump, i.e., the physical barrier separating the inside of the pump from its external environment (and vice versa). Escape of fluid from inside the pump housing across the physical barrier constitutes a leak. The pumps and hydraulic systems described herein exhibit fewer leaks under more aggressive pumping conditions, while providing improved pump performance over longer periods of time, compared to conventional pumps and systems. 
         [0014]    Since the magnet cup constitutes a portion of the pump housing, in many embodiments of the invention at least one sensor is integrated into a wall of the magnetic cup so as not to be wetted by the pumped fluid. Such an “integral sensor” is associated with the magnetic cup in such a way that it functions essentially as a part of the cup instead of as a separate, discrete component. The integrated sensor is any of various sensors that can quantitatively react to their respective parameters as sensed across a wall or portion of a wall of the magnet cup, or a cross a wall or other fluid barrier coupled to a wall of the magnet cup. The sensor(s) can be one or more of pressure sensors, temperature sensors, or other sensors such as, for example, conductivity sensors, resistivity sensors, turbidity sensors, flow-rate (viscosity) sensors, pH sensors, dissolved gas sensors, or sensors of other fluidic variables such as turbidity, dissolved ions, and optical absorption, or sensors that detect rotation of elements of the pump motor. A conductivity sensor can be used, for example, to shut a pump down in the event of a “running dry” condition. A rotation sensor can be used, for example, if a motor controller is sensorless, to sense rotation direction or whether rotation of a pumping element is occurring at all. An example rotation sensor is based on the Hall effect. A dissolved gas sensor can be used to control a degassing system. Exemplary sensor types include strain gauge sensors, capacitive sensors, resistive sensors, piezoelectric sensors, and electrodes such as ion-specific electrodes. The sensors can be connected to other electronics by conventional conductors (wires, pins, and the like) or, if permitted by the type and general configuration of the sensor, by wireless connections. Other Hall-effect sensors detect mechanical motion of one or more internal magnetic elements. Inductive sensors include, for example, a voice coil for measuring acoustic signals and/or fine-positioned displacements. Another exemplary inductive sensor receives and/or transmits RF signals. 
         [0015]    Although embodiments shown herein describe sensors as being mounted to a distal-end wall of the magnet cup, the location of sensors is not limited to a particular wall of the magnet cup, or even to a magnet cup at all. For example, sensor(s) can be located at either the pump-inlet region of the magnet cup (for sensing, e.g., inlet pressure) or the pump-outlet region of the magnet cup (for sensing, e.g., outlet pressure). Exemplary mounting arrangements of the sensor to a wall of the magnet cup or other region of the pump housing, thus producing an integral sensor, include direct welded, separate membrane welded, over-molded, adhesive-mounted, statically sealed in place, clamped, mechanically joined, and integrated directly into the wall by molding or casting. Many types of sensors do not actually contact the fluid in the pump. For example, a strain-gauge based pressure sensor is capable of sensing pressure through the wall of a thin-walled magnet cup or through a localized thinner region of a magnet cup. Such a sensor transducer can be coupled directly to an “unpierced” wall of the magnet cup. A desirable method for mounting a capacitive sensor is resistance welding to a wall (e.g., the distal end wall) of a non-magnetic metal or injection-molded polymeric magnet cup. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a coronal section of an embodiment of a magnetically-driven pump comprising a pump head and a housing. A sensor transducer is integrated into a wall of the magnet cup and directly connected to a circuit board. 
           [0017]      FIG. 2  is a coronal section of an embodiment of a compact magnetically-driven pump, comprising a pump head and a housing. A sensor transducer is disposed in a dry cavity within the wall of the magnet cup so as not to be wetted by the fluid being pumped. The integral sensor transducer may be wired directly to a nearby circuit board or it may communicate wirelessly with nearby electrical components. 
           [0018]      FIG. 3  is a coronal section of an embodiment of a compact magnetically-driven pump comprising a pump head and a housing. A sensor transducer is integrated into a wall of the magnet cup, and a dry sidewall portion of the sensor transducer is directly connected to a circuit board. 
           [0019]      FIG. 4  is a first perspective view of an exemplary embodiment of a magnetic cup, as used for example in the embodiment shown in  FIG. 3 , in which the integral sensor transducer is directly connected to an annular circuit board. 
           [0020]      FIG. 5  is a second perspective view of the magnetic cup shown in  FIG. 4 . 
           [0021]      FIG. 6  is a first cross-sectional view showing components at the distal end of the magnetic cup shown of  FIG. 4 . 
           [0022]      FIG. 7  is a third perspective view of the magnetic cup shown in  FIG. 4 , also showing the driven magnet in situ. 
           [0023]      FIG. 8  is a second cross-sectional view of the magnetic cup shown in  FIG. 4 , also showing the driven magnet in situ. 
           [0024]      FIG. 9  is an exploded perspective view showing coaxial components of the magnetic cup of  FIG. 4 . 
           [0025]      FIG. 10  is a first perspective view of an alternative embodiment of the magnetic cup shown in  FIG. 2 . 
           [0026]      FIG. 11  is a second perspective view of the magnetic cup shown in  FIG. 10 . 
           [0027]      FIG. 12  is a first cross-sectional view of the distal end of the magnetic cup shown in  FIG. 10 , in which a sensor transducer can be disposed within a dry cavity in the distal end wall of the magnetic cup and conveniently wired to a nearby printed circuit board. 
           [0028]      FIG. 13  is a third perspective view of the magnetic cup shown in  FIG. 10 , showing the driven magnet in situ. 
           [0029]      FIG. 14  is a second cross-sectional view of the magnetic cup shown in  FIG. 10 , including a sectional view of the driven magnet. 
           [0030]      FIG. 15  is an exploded view showing coaxial components of the magnetic cup of  FIG. 13 . 
           [0031]      FIG. 16  is a perspective view of an embodiment of the magnet cup in which sensor(s) are integrated into the side wall. 
           [0032]      FIG. 17  is a side elevation view of an embodiment of the magnet cup in which a sensor is integrated into the distal end of the magnet cup using a static seal. 
           [0033]      FIG. 18  is an exploded view of the magnet cup and sealed-sensor embodiment shown in  FIG. 17 . 
           [0034]      FIG. 19  is a block diagram showing hardware and software components of an exemplary feedback-control system that may be used to monitor and control a fluid pump. 
       
    
    
       [0035]    The foregoing and additional objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
       DETAILED DESCRIPTION 
       [0036]      FIG. 1  depicts an embodiment of a pump assembly  10  including a driver portion  12  and a pump head  14 . The pump head  14  includes an inlet port  16 , an outlet port  18 , a driving gear  20 , a shaft  22 , a driven magnet  24 , and a magnet cup  26 . The magnet cup  26  is internal to the driver portion  12 . The magnet cup  26  has side walls  26   a  and a distal-end wall  26   b  that surround and are coaxial with the driven magnet  24 . The side walls  26   a  and distal-end wall  26   b  serve to isolate the driven magnet  24  (which, along with the pump head  14 , is generally bathed in the fluid being pumped) from electrical parts of the assembly that are kept “dry,” i.e., not wetted by the fluid being pumped. The fluid-wetted interiors of the pump head  1 A and magnet cup  26  comprise a “pump housing.” Coaxially surrounding the magnet cup  26  is a stator  32 , located outside the pump housing, that is magnetically coupled to the driven magnet  24  across the side walls  26   a  of the magnet cup. The stator  32  is contained in an enclosure  34 . The enclosure  34 , being outside the pump housing, is “dry.” In the embodiment shown in  FIG. 1 , the enclosure  34  and pump head  14  are mounted end-to-end so that a large part of the pump head  14  extends from the driver portion  12 . 
         [0037]    Mounted to the distal-end wall  26   b  is a sensor transducer  28 , comprising a parameter-sensitive surface (i.e., a surface that responds in a measurable way to the parameter to which the sensor is sensitive). In this embodiment, the sensor transducer  28  is sealingly mounted with its parameter-sensitive surface facing the driven magnet  24 . The phrase “sealingly mounted” means that the sensor transducer  28  is held in a position so as to maintain contact with at least a portion of the mounting surface at one or more contact points at which a barrier prevents fluid from passing through or across the surface. The barrier may take the form of, for example, the surface itself, an o-ring, an absorbent material, an adhesive material, or the like. As a purchased component, the sensor transducer  28  may be a type capable of being operated while in contact with (wetted by) fluid. But, in the various embodiments discussed herein, the sensor transducer desirably also is capable of being operated (or is configured specifically for operation) in a dry condition, i.e., without being wetted by the pumped fluid. At least the parameter-sensitive surface can be incorporated into a wall of the magnet cup. The sensor transducer  28  in this embodiment is electrically connected directly to a printed circuit board  34  situated outside the magnet cup  28 . The printed circuit board  30  contains an electronic circuit that, for example, receives transducer signals from the sensor transducer  28  and conditions the transducer signals for use by other electronics (not shown), such as driver electronics for the stator  32 . For example, the transducer signals can be used for feedback control of the driver electronics for the stator  32 . 
         [0038]      FIG. 2  depicts another embodiment of a pump assembly  50  configured to occupy less space than the embodiment shown in  FIG. 1 . The pump assembly  50  comprises a driver  52  and a pump head  54 . The pump head  54  includes an inlet port  56 , an outlet port  58 , a driving gear  60 , a driven gear  61 , a shaft  62  to which the driving gear is axially affixed, a driven magnet  64 , and a magnet cup  66 . The magnet cup  66  has side walls  66   a  and a distal-end wall  66   b  that surround and are coaxial with the driven magnet  64 . Mounted to the distal-end wall  66   b  is a sensor transducer  68 . The sensor transducer  68  is mounted such that its parameter-sensitive surface faces the interior of the magnet cup so as to sense its respective parameter through the distal-end wall  66   b.  Other portions of the sensor transducer  68  extend from the magnet cup  66 . The sensor transducer  68  is electrically connected to a printed circuit board  70 . Coaxially surrounding the magnet cup  66  is a stator  72  that is magnetically coupled to the driven magnet  64  across the side walls  66   a  of the magnet cup. The stator  72  is contained in an enclosure  74 , which also contains the printed circuit board  70 . The sensor transducer  68  can be connected to the PCB  70  by wiring (not shown). Alternatively, the sensor transducer  68  can be coupled to the PCB  70  wirelessly using, for example, radio frequency (RF) or infrared (IR) signals for delivering data to the PCB  70 . The printed circuit board  70  desirably has not only electronics that receive and condition transducer signals from the sensor transducer  68  but also driver electronics for the stator  72 . In this embodiment, a portion of the pump housing is located inside a thick wall of the enclosure  74 , which reduces the relative volume occupied by the pump assembly  50 . 
         [0039]      FIG. 3  depicts another embodiment of a pump assembly  100  also configured to occupy reduced volume. The pump assembly  100  comprises a driver  102  and a pump head  104 . The pump head  104  includes an inlet port  106 , an outlet port  108 , a driven gear  110 , a driving gear  111 , a shaft  112  axially coupled to the driving gear  111 , a driven magnet  114 , and a magnet cup  116 . The magnet cup  116  has side walls  116   a  and a distal-end wall  116   b  that surround and are coaxial with the driven magnet  114 . Mounted to the distal-end wall  116   b  is a sensor transducer  118 . The sensor transducer  118  is mounted such that its parameter-sensitive surface faces the driven magnet  114  without being wetted by the pumped fluid normally in the magnet cup. Other portions of the sensor transducer  118  extend from the magnet cup to a first printed circuit board  120 . Coaxially surrounding the magnet cup  116  is a stator  122  that is magnetically coupled to the driven magnet  114  across the side walls  116   a  of the magnet cup. The stator  122  is situated within an enclosure  124 , which also contains the first printed circuit board  120  to which the sensor transducer  118  is mounted. The first printed circuit board  120  is connected to a second printed circuit board  126  by conductive pins  121 . The first printed circuit board  120  contains electronics that receive and condition transducer signals from the sensor transducer  118 , and the second printed circuit board  126  contains driver electronics for the stator  122 . In this embodiment the pump head  104  extends at least partially into the wall of the enclosure  124 , which reduces overall volume occupied by the pump assembly  100 . 
         [0040]    The magnet cup  116  can be made of any of various rigid materials that are not magnetic. For example, the magnet cup  116  can be made of a non-magnetic metal or metal alloy, in which event the magnet cup can be formed by machining, deep-drawing, casting, or the like. As another example, the magnet cup can be made of a polymeric or copolymeric material formed by machining or molding, for example. The polymeric or copolymeric material can be reinforced using fibers, particles, or other suitable non-magnetic material. A polymeric magnet cup may be transparent or translucent to selected wavelengths of electromagnetic radiation so as to enable a non-wetted sensor to detect, across the wall of the magnet cup, optical properties or variation in such properties of the fluid being pumped. 
         [0041]    An exemplary embodiment of a magnet cup  150  made of metal is shown in  FIG. 4 , in which the depicted cup includes a cylindrical body  152 . The body  152  includes a proximal mounting flange  154  for mounting the cup to a pump head (see  FIG. 3 ). The body  152  also includes a distal-end plate  156  to which a sensor transducer  158  is bonded such that the parameter-sensitive surface of the transducer faces the interior of the magnet cup. The opposing (outward facing) surface of the sensor transducer  158  is visible in the drawing, connected by pins  160  to an annular circuit board  162 . The circuit board  162  includes male connector pins  164  by which the circuit board is electrically connected to other electronics located on a separate circuit board (not shown). The magnet cup  150  of  FIG. 4 , also shown in a different perspective view in  FIG. 5 , is similar to the magnet cup  26  shown in  FIG. 1  and the magnet cup  116  shown in  FIG. 3 . A cross-sectional view along cut lines shown in  FIG. 5  provides some additional detail, for example purposes, as shown in  FIG. 6 . Depicted in  FIG. 6  are the cylindrical body  152 , the distal-end plate  156  of the magnet cup  150 , the sensor transducer  158 , the printed circuit board  162 , and connecting pins  164 . Also shown in the figure is a cover  166  configured to fit over the sensor transducer  158  and circuit board  162 , with provision for the pins  164  to extend through the cover  166 . Note that the cup  150  shown in  FIG. 4  is similar to the cup of  FIG. 6 , but lacks the cover  166  shown in  FIG. 6 . Similarly, the cup  26  shown in  FIG. 1  includes a cover, while the cup  116  shown in  FIG. 3  lacks the cover. 
         [0042]    In the embodiment of  FIG. 6 , the sensor transducer  158  is sealingly integrated into the distal-end plate  156 , such that the sensor transducer  158  remains in contact with, and surrounded by, the annular printed circuit board  162 . This allows electrical signals from the sensor transducer  158  to be directly connected to hardware components on the circuit board  162  via the pins  160  (see  FIG. 4 ) without the need for separate connecting wires and associated through-holes. The sensor transducer  158  is integrated with the dry side of a thin plate  156 , which forms a barrier between wet and dry environments, while still allowing the sensor transducer  158  to detect one or more fluidic parameters of interest. Placing the sensor transducer  158  adjacent a wet surface prevents direct contact with pumped fluid such that the sensor transducer  158  operates as a “non-wetted” sensor. The integration of the sensor transducer  158  with the plate  156 , and the direct connection of the sensor transducer to the circuit board  162  form a mechanically rigid unit that is more likely to ensure the integrity of electrical continuity for reliable transmission of sensor data. 
         [0043]      FIG. 7  is another perspective view of the magnet cup  150 , including the cover  166 . A cross section of the magnet cup  150  and driven magnet  122  is shown in  FIG. 8 .  FIG. 9  is an exploded view of the magnet cup  150  showing features used for making the interior of the magnet cup  150  pressure-compliant. See U.S. Patent Application Publication No. US 2009-0060728 filed on Aug. 29, 2008, incorporated herein by reference, particularly the embodiments of pressure-absorbing members shown in FIGS. 1E, 2, 3, 4A, 4B, and 5, and the accompanying discussion in paragraphs 42-48 and 53-60 of that reference. These features include a plug 168 (made of, e.g., fluorosilicone foam) and retainer 170. Also shown are the driven magnet 172 and a retainer shoe 174. 
         [0044]    An exemplary embodiment of a magnet cup  200  made of a molded rigid polymer material is shown in  FIG. 10 , in which the depicted cup includes a cylindrical body  202 . The body  202  includes a proximal mounting flange  204  for mounting the cup to a pump head (not shown). The body  202  also includes stiffening ribs  206  and a distal-end wall  208  in which a sensor transducer  210  is bonded such that a parameter-sensitive surface of the transducer faces the interior of the magnet cup. The distal-end wall  208  also includes stiffening ribs  212 . The sensor transducer  210  comprises pins  214  by which the sensor transducer is electrically connected to a circuit board (not shown). The magnet cup  200  of  FIG. 10  is otherwise similar to the magnet cup  66  shown in  FIG. 2 . 
         [0045]    Details of the magnet cup  200  are shown in  FIGS. 11 and 12 , in which a portion of the body  202  is shown along with the distal-end wall  208 . The distal-end wall  208  defines a cavity  216  in which the sensor transducer  210  is sealingly mounted (e.g., by use of adhesive) so that the sensor transducer  210  operates as a non-wetted sensor.  FIG. 13  shows another perspective view of the magnet cup  200 , and a cross section of the magnet cup  200  is shown in  FIG. 14 . Further details are provided in  FIG. 15 , including certain features used for making the interior of the magnet cup  200  pressure-compliant. These features include a plug  218  (made of, e.g., fluorosilicone foam) and retainer  220 . Also shown are the driven magnet  222  and a retainer shoe  224 . 
         [0046]      FIG. 16  shows an alternative embodiment of a magnetic cup  230  that includes a a side wall  232 , a distal-end wall  234 , a proximal mounting flange  236 , and an assembly  238  of one or more non-wetted sensors  240 . In this embodiment, the sensor assembly  238  is integrated into the side wall  232  instead of being integrated into the distal-end wall  234 . Individual sensors  240  may be disposed in a ring around the circumference of the magnetic cup  230  such that they protrude above the surface of the cup  230 . Alternatively, the sensors  240  may be configured as mini- or micro-mechanical sensors disposed within or on the surface of the body  232 . The sensor assembly  238  may be configured as a narrow ring as shown, a wide ring, or an outer cylinder that is coaxial with side wall  232 . 
         [0047]      FIGS. 17 and 18  show an alternative embodiment of a magnetic cup  250 , that includes a side wall  252 , a distal-end wall  254  that may be thicker than the side wall  252 , a proximal mounting flange  256 , and a non-wetted sensor  258 . In this embodiment, the sensor  258  may be inset into the distal-end wall  254  and held in place by a cover  260  and a seal  262 . The seal  262  may be an adhesive, a gasket, an o-ring, or the like. 
         [0048]      FIG. 19  shows an exemplary feedback control system  300  for a self-modulating pump assembly that includes one or more sensing components as described above. For example, the feedback control system  300  may be used to maintain a prescribed temperature or pressure associated with the pump assembly. As discussed above, all components of the control system can be located in the pump assembly without the need for additional housings, wiring, or seals. Shown are software and hardware portions,  302  and  304 , respectively. The exemplary software portion  302  includes an integral controller  306  and a proportional controller  308  typically used in feedback-control systems. The exemplary hardware portion  304  includes a digital-to-analog converter (DAC)  310 , an analog-to-digital converter (ADC)  312 , a motor controller (BLDC)  314  for driving the motor stator (BLDC motor)  316 , and thus the pump  318 , and at least one sensing component  320 . 
         [0049]    To provide feedback control to the pump  318  based on measurements obtained by the sensing component  320 , a measured feedback signal  322  from the sensing component  320  is converted by the ADC  312  into a first digital feedback signal  324  that can be processed by the software portion  302 . Additional data may be combined with the first digital feedback signal  324  from an external source by a second digital feedback signal  326 . A first multiplexer  328  combines the digital feedback signals  324 ,  326  for processing by the controllers  306 ,  308 . A proportional control signal  330  and an integral control signal  332  may then be combined by a second multiplexer  334  to form a composite control signal  336 . The composite control signal  336  may then be transmitted to the DAC  310  for conversion into an analog control signal  338 . The analog control signal  338  may then be processed by the BLDC controller  314 , and subsequently delivered at an appropriate time to the motor  316  for controlling the performance of the pump  318 . 
         [0050]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.