Patent Application
20160047365
Various embodiments relate generally to pneumatic pumps with low-acoustic output.
Pneumatic pumps are compressors of air. Pneumatics are a branch of fluid power, which includes both pneumatics and hydraulics. Pneumatics may be used in many industries, factories, and applications. Pneumatic instruments are powered by compressed air. For example, many dental tools are powered by compressed air. Auto mechanics may use air tools when repairing or replacing parts on vehicles. Pneumatic pumps may inflate inflatable devices, such as tires or air mattresses.
Apparatus and associated methods relate to nutating a piston drive linkage oriented around a longitudinal axis in response to the rotation of a drive shaft about a drive axis of rotation, said longitudinal axis being offset and canted with respect to said drive axis of rotation. In an illustrative example, the piston drive linkage may be formed as an umbrella shape with multiple arm members extending radially from the longitudinal axis. The distal ends of each of the radial arm members may attach to a stationary piston crank. In some examples, the piston crank may be flexible. The nutating motion of the piston drive linkage may impart a substantially linear motion profile to each piston crank. The motion profile may be, in some examples, substantially parallel to the drive axis of rotation. A shaft extending along the longitudinal axis from the piston linkage may advantageously freely insert into and rotate within a receptacle of a spinner body being rotated around the drive axis of rotation.
Various embodiments may relate to a pneumatic pump having a canted off-axis drive to reciprocate a number of pliable pistons operably connected to an equal number of radially arranged piston cranks, with an optimized Moment-Insertion Ratio (MIR) between (i) a radial moment arm of any one of the piston cranks and (ii) a shaft insertion depth into a canted off-axis driver bearing. In an illustrative example, the optimal MIR may yield substantially reduced wear and improved service life when the forces that the canted off-axis driver bearing imparts radially onto the shaft are substantially equal and opposite in magnitude. The radial moment arm may extend from an axis of the shaft to, for example, any of at least two linearly actuatable pliable-pistons. In some embodiments, each of the radially arranged piston cranks may be coupled to the shaft at a common point along the shaft.
In some embodiments, the pliable-piston driver may provide active drive in both an up-stroke and a down-stroke direction to each of a plurality of pliable pistons. Each of the plurality of pliable pistons may be diaphragm pistons, for example. In some embodiments, the pliable-piston driver may have a drive axle coupled to a drive motor in an off-axis canted fashion. In some embodiments, a drive axle of the canted off-axis pliable-piston driver may traverse a conic surface while maintaining a static rotational orientation of the drive axle. A vertex of the conic surface may be collinear with a central axis of the drive motor, for example. In some embodiments, the pneumatic pump may advantageously provide continuous flow while simultaneously minimizing pump noise.
Various embodiments may achieve one or more advantages. For example, some embodiments may provide long-life, maintenance free and substantially continuous flow of air to a device. Such continuous air flow may advantageously improve comfort of patients wearing pneumatic compression boots, for example. Continuous flow may improve linear ramping of pressures in certain applications. Reduced pulsating of instruments may result from the use of phased piston pumping of air. In some embodiments, the flow rate may be increased by the use of two or more pistons. The cost of driving two or more pistons may be minimized by driving all pistons with a single unitary piston driving element.
Some embodiments may, for example, exhibit substantially improved durability and service life. For instance, certain failure modes associated with wear in the rotating canted off-axis spinner and/or on the shaft of the piston driver may be substantially reduced. In various examples, some embodiments may exhibit substantially reduced failures due to relative motion between the non-rotating shaft and the rotating spinner. In some implementations, component costs may be reduced, less costly materials may be selected to achieve a predetermined service life, and/or reduced maintenance may be achieved.
The details of various embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
To aid understanding, this document is organized as follows. First, some advantages of a phased soft-piston pneumatic pump are briefly introduced using an exemplary scenario of use with reference to
Each of the N deformable pistons may receive air from an input port 145 and deliver the air to a distribution module 150 via the exhaust manifold 140. In an exemplary embodiment, the distribution module 150 may have one or more flow controllers 155. Each flow controller may receive one or more control signals from a system controller 160. Each of the flow controllers 155 may have an exit port 180. Each of the exit ports 180 may be configured to provide connection to an output pneumatic line and/or device.
While controlling and/or monitoring the operation of the motor 120 and/or distribution module 150, the system controller 160 may further be operatively coupled to an input/output module 170. The input/output module 170 includes a user input/output interface 175. The input/output module 170 may communicate, for example, system status information or global commands with a communications network. For example, the input/output module 170 may report system status information to a logging center. In some embodiments the system controller 160 may receive local operating command signals via the user input/output interface 175. The input/output module 170 may communicate by transmitting and/or receiving digital and/or analog signals using wired and/or wireless communications protocols and/or networks. For example, the system controller 160 may receive operating command signals from a mobile device, and/or transmit status information to the mobile device.
In the depicted embodiment, as the drive axle 250 of the drive motor 205 rotates, the drive cam 245 may rotate. As the drive cam 245 rotates, the central axle 240 of the umbrella piston driver 235 may be driven about a central axis 255 of the drive motor 205. The central axle 240 of the umbrella piston driver 235 may define a surface of a cone (not depicted). The canted off-axis central axle 240 orients the umbrella piston driver 235 so that a diaphragm piston connected to a first side 260 may be at an upstroke position and a diaphragm piston 225 connected to a second side 265 may be at a down stroke position.
The cranks 340 may securely couple to an umbrella piston driver 345. The piston cranks 340 may be elastic so as to allow angular deformation of the piston cranks 340. An umbrella drive axle 350 may couple to a central hub 355 of the umbrella piston driver 345. The umbrella drive axle 350 may couple to a motor coupling cam 360. The umbrella drive axle 350 may be coupled to the motor coupling cam 360 in a receiving aperture. The receiving aperture may receive first a ball bearing 365 and then the umbrella drive axle 350. The motor drive cam 360 may be configured to couple to a motor axle 370. When the motor drive cam 360 is coupled to both the motor axle 370 and the umbrella drive axle 350, the umbrella drive axle 350 may be canted with respect to a longitudinal axis of the motor drive axle. In some embodiments, the umbrella drive axle 350 may freely rotate within the receiving aperture of the motor drive cam 360. In some embodiments the umbrella drive axle 350 may freely rotate within an aperture in the central hub 355 of the umbrella piston driver. In an exemplary embodiment, the umbrella drive axle 350 may freely rotate within both the aperture in the central hub 355 and within the receiving aperture of the motor drive cam 370.
An exhaust cavity may be defined by an internal cavity created by a front housing 375 and a valve plate 380. Exhaust valves 385 may be configured to provide unidirectional fluid transport from the pneumatic pistons 335 and the exhaust cavity. Exhaust holes in the valve plate 380 may be aligned to the pneumatic pistons 335. The exhaust valves may permit fluid flow through the aligned holes into the exhaust cavity. The fluid in the exhaust cavity may exit the cavity through an exit port 390.
In various embodiments, the motor drive cam 405 may have an umbrella end 435 and a motor end 440 opposite the umbrella end 435. The motor drive cam 405 may be configured to couple to a motor axle on the motor end 440 of the motor drive cam 405. The motor drive cam 405 may be configured to couple to the piston drive axle 420 on the umbrella end 435 of the motor drive cam 405. The piston drive axle 420, when coupled to the motor drive cam 405, may project from the motor drive cam 405 from a radial distance, r, from the central axis 415. The piston drive axle 420 may be canted at an angle, α, with respect to the central axis 415. The vertex 430 may be at a vertical distance, h, from the umbrella end 435 of the motor drive cam 405. The angle, α, may relate the radial distance, r, and the vertical distance h as:
The umbrella piston driver 410 may have a plurality of piston arms 445 radially extending from the canted axis 425. Each piston arm 445 may be configured to securely attach to a piston crank. In some embodiments, a piston interface member may extend radially from the canted axis 425 to provide piston interfaces for pneumatic pistons. In the depicted embodiment, a top surface 450 of the piston arms 445 may not be in a plane perpendicular to the canted axis 425, but instead may be deflected below a plane perpendicular to the canted axis 425, toward the motor drive cam 405. In some embodiments, an angle of deflection, β, may be substantially equal to the angle, α. In such an embodiment, the top surface 450 of the piston arm 445 may transition from being coplanar to a plane perpendicular to the central axis 415 and being at an angle of 2α with a plane perpendicular to the central axis 415, as the motor drive cam 405 rotates.
In
In
In the depicted figure, some components defining an air flow path through the pump include a valve plate 905, a diaphragm body 910, and a piston block 915. When assembled, the diaphragm body 910 is sealed on top by the valve plate 905, and from the bottom by the piston block 915.
On its top side, the valve plate 905 includes a number of apertures forming collectively an outlet port 920. On an upstroke, air is forced out of a piston chamber 925 in fluid communication with the ambient atmosphere, for example, through the apertures of the outlet port 920. The upstroke is effected by the wobble plate (not shown) driving the flexible diaphragm piston 930 upward, collapsing the volume of the chamber 925. The wobble plate effects this upstroke motion by its connection to a piston crank 935 extending from an exterior of the piston 930.
The diaphragm body 910 includes a flexible web of material that extends between each of the pistons 935. The flexible web of material provides sealing to isolate and separate the air flow paths used by each of the pistons. To support the diaphragm body 910 in the regions between the pistons, the piston block 915 provides substantially rigid structural support from below. The piston block 915 includes an aperture 940 through which the piston 930 and piston crank 935 are inserted during assembly.
To explain the air flow path on a down stroke of the piston 930,
The piston block 915 includes a pair of inlet apertures 950 associated with the piston 930. During a down stroke, air is drawn into the piston via the inlet apertures 950. In the depicted embodiment, the inlet apertures 950 are divided by a bridge.
The flexible diaphragm body 910 is formed with a cut out configured to create a flap valve 955 aligned with the inlet apertures 950. During a down stroke, a pressure drop in the chamber 940 causes the flap valve 955 to lift as air is drawn in. During an upstroke, pressure increases in the chamber 940 causes the flap valve to seal the inlet apertures 950. The bridge between the apertures may support the flap valve 955, which may advantageously resist fouling the flap valve 955 and not allowing it to get sucked into the apertures 950.
A lip around the top of the piston 930 forms a seal with the bottom of the valve plate 905. In the depicted figure, the bottom surface of the valve plate 905 includes a shallow trench that provides fluid communication from the flap valve 955 into chamber 925. The trench by itself does not provide fluid communication to the top of the valve plate 905. In the depicted example, the trench includes a U-shape with a vertex aligned above the flap valve 955, and two ends 965 that terminate aligned above the chamber 925. During the down stroke, the chamber is sealed from fluid communication through the outlet ports 920 by a flap valve 975.
An input pressure may correspond to an envelope 1045 representative of the maximum pressure of the four membrane pistons. The periodic frequency of the envelope 1045 is four times the period of each of the relations 1015, 1020, 1025, 1030. The peak-to-peak amplitude of the envelope 1045 is much smaller than the peak-to-peak envelope of any of the four relations 1015, 1020, 1025, 1030. The amplitude of the peak-to-peak envelope of the input pressure may correspond to a noise level associated with the input port, for example. In some embodiments, the input port may present an input pressure that is lower than the ambient pressure. In some embodiments, an exemplary pneumatic pump may be configured as a vacuum pump, for example. As the number of membrane pistons increases, the periodic frequencies of both input and exhaust pressures may increase. As the number of membrane pistons increases, the peak-to-peak amplitude of the input and exhaust port pressures may decrease. In some embodiments, the noise behavior of the pump may correlate to the number of membrane pistons.
The measured noise spectrum 1120 represents a background ambient noise of the testing chamber. The measured noise spectrum 1125 corresponds to a pneumatic pump operating with nine volts applied to a pump motor. The measured noise spectrum 1130 corresponds to a pneumatic pump operating with twelve volts applied to a pump motor. Note that the twelve volt operating pump produces a noise spectrum that is less than or equal to the noise reference level NC-25 1135 at nearly every frequency measured. Also note that the noise spectrum corresponding to a nine volt operating pneumatic pump is less than or equal to the noise reference level NC-20 1140 at nearly every frequency measured. The tested pumps operating at both nine volts and twelve volts each have a series of pump membranes that are driven by an oscillating umbrella linkage. The oscillating umbrella linkage may be coupled to a drive motor in an off-axis canted fashion. This off-axis canted coupling may produce a transitive wave motion in the oscillating umbrella linkage. The transitive wave motion may produce a series of phased drive motions to a corresponding series of pump membranes.
In various embodiments, the spinner 1300 may provide a nutating motion profile for an umbrella linkage or wobble plate, such as the wobble plate 1215, for example. When coupled to a drive shaft on a proximal face, with the wobble plate shaft (e.g., shaft 1220) inserted into the eccentric shaft receptacle, the spinner 300 may impart a nutating motion to the wobble plate in response to rotation of the drive shaft about a drive axis of rotation. In various implementations, the longitudinal axis of the wobble plate shaft may be substantially offset and canted with respect to the drive axis of rotation.
In some embodiments, the ball bearing 1310 may be a steel bearing ball in the bottom of the eccentric hole. The ball may reduce wear between shaft end and a bottom of the eccentric hole.
In some embodiments, assembly may include inserting the piston coupling member 1510 of the rubber diaphragm forming chamber walls 1515 into the corresponding attachment aperture 1230 at each end of wobble plate radial arms. For example, the wobble plate 1205 may be pressed onto the shaft 1220 that rests on the ball 1310 in the eccentric hole 1305.
In an illustrative example, the spinner 1300 is a small piece that may be coupled to an electric motor. The shaft receptacle 1305 may be an eccentric hole going down from the top surface of the spinner 1300, and piercing the surface off center. In some embodiments, the shaft receptacle 1305 receives a steel shaft that is fixed rotationally by its attachment to the piston coupling members 1510 of the pumping diaphragm via a plastic wobble plate 1205. In various examples, as the spinner 1300 rotates with the motor shaft 1220, the eccentric shaft 1220 and attached wobble plate 1205 tilt back and forth, moving the wobble plate radial arm members 1225 and/or their corresponding attachment apertures 1230 in a roughly vertical motion.
Some failure modes may be described in terms of forces. One exemplary force is the force of the shaft pressing on the ball at the bottom of the hole. This force includes a component directed along the central axis of the eccentric hole. A second force is a torsional force, pressing the bottom of the shaft into the eccentric hole wall on the side nearest the motor shaft. At the same time, it presses the shaft where it exits the spinner into the eccentric hole wall on the side away from the motor shaft. It is believed that the friction-induced heat may soften the spinner's material and allows the shaft to dig into the hole sidewalls and allows the ball to migrate through the softened material until it is out of position and no longer supporting the shaft.
In an experiment, pumps on test are measured periodically to track performance. Tests are run under standard operating conditions as well as under accelerated life testing conditions. A failure may be determined as the pump's output falling below a flow rate threshold, or a specified drop in pump efficiency.
It is believed that some spinners may experience one or the other of these wear patterns, while some may experience both. Both cases result in the eccentric shaft shifting to a position that provides an attenuated pumping motion and thus attenuated output. In some embodiments, one exemplary objective may include optimization to manage excess heat and wear created during operation to allow the pump to operate for longer periods before failing.
An exemplary optimization criteria is to substantially equalize the magnitudes of the forces F3 and F4, at the respective proximal and distal ends of the portion of the shaft 1220 inserted into the spinner shaft receptacle 1305.
Certain wear failure modes are a function of the moment arm applied to the shaft 1220 in the spinner shaft receptacle 1305. An exemplary optimization method involves calculating the sum of the moments about point D, which lies along the axis of the shaft and in a plane that is tangent to a top surface of the spinner at the aperture of the shaft receptacle 1305. The moment sum about point D is directly proportional to the dimensionless ratio of L1/L3. As such, the moment sum about point D may be minimized by minimizing L1 and/or maximizing L3 within available practical limitations.
In some implementations, assembly of the wobble plate 2210 to the bearing 2220 may be advantageously simplified by a substantially low friction coupling between the wobble plate 2210 and the bearing 2220. In various embodiments, the inner diameter of the aperture 2230 may be slightly larger than the outer diameter of the bearing 2220, such that the two do not have a tight interference fit. Accordingly, some wobble plates may be easily assembled or removed by hand, thereby yielding the ability to assemble, service or replace wobble plates or spinner/bearing components without the need for tools, adhesives, or other supplements. In some implementations, the interface between the wobble plate 2210 and the bearing 2220 may provide a freely releasable coupling along a longitudinal axis of the cylindrically shaped shaft 2215. In some implementations, the interface between the bearing 2220 and the shaft 2215 may provide a freely releasable coupling along a longitudinal axis of the cylindrically shaped shaft 2215.
Some embodiments may include a chamfer on the aperture 2230 to promote self-alignment of the aperture 2230 to the bearing 2220. Some embodiments may include a chamfer on a distal end of the shaft 2215 to promote alignment when assembling the bearing 2220 to the shaft 2215.
The shaft 2315 includes a disc forming a shoulder having a top surface 2325 and a perimeter 2330. Extending down from the disc along a longitudinal axis of the shaft 2315 is a spinner shaft 2335. Extending up from the disc along the longitudinal axis of the shaft 2315 is a bearing shaft 2340. In the depicted figure, a radius of the disc perimeter 2330 is greater than a radius of either the spinner shaft 2335 or the bearing shaft 2340.
When assembled, the umbrella linkage 2305 is substantially supported by an outer race 2345 of a bearing, and the bearing shaft 2340 substantially supports an inner race of the bearing. In the depicted figure, material of the umbrella linkage is formed (e.g., removed) so as not to make contact with the inner race 2350. Shoulders are formed in a top annular ring, for example, inside the aperture of the umbrella linkage; these shoulders make contact with the outer race 2345. The inner race 2350 is separated from the outer race 2345 by an annular gap.
The diameter of the disc perimeter 2330 is less than an inner diameter of the outer race 2350, such that the disc does not make contact with the outer race 2345. In operation, the umbrella linkage 2305 is substantially free to rotate about a longitudinal axis 2360 of the shaft 2315 and relative to the inner race 2350-connected shaft 2315.
The spinner 2310 includes a receptacle to couple to a rotating drive shaft configured to rotate about an axis of drive rotation 2365. With respect to the drive rotation axis 2365, the longitudinal axis of the shaft 2315 is off-axis and canted at an angle 2370 determined by the receptacle in the spinner 2310.
In some embodiments, the spinner shaft 2335 may be keyed (e.g., D-shaped or with a flat) to a corresponding D-shaped receptacle in the spinner 2310. In some embodiments, the spinner shaft 2335 may be cylindrical and configured to freely spin in the receptacle in the spinner 2310.
In some implementations, assembly of the umbrella linkage 2305 to the bearing outer race 2345 may be advantageously simplified by a substantially low friction coupling between the umbrella linkage 2305 and the bearing outer race 2345. In various embodiments, the inner diameter of an aperture that receives the outer race 2345 may be slightly larger than the outer diameter of the bearing outer race 2345, such that the two do not have a tight interference fit. Accordingly, some umbrella linkage 2305 may be easily assembled or removed by hand, thereby yielding the ability to assemble, service or replace umbrella linkage 2305 or the bearing components without the need for tools, adhesives, or other supplements. In some implementations, the interface between the umbrella linkage 2305 and the bearing may provide a freely releasable coupling along a longitudinal axis of the cylindrically shaped shaft 2340. In some implementations, the interface between the bearing inner race 2350 and the bearing shaft 2325 may provide a freely releasable coupling along a longitudinal axis of the cylindrically shaped shaft 2340.
Some embodiments may include a chamfer on the aperture in the umbrella linkage 2305 to promote self-alignment of the aperture to the bearing outer race 2345. Some embodiments may include a chamfer on a distal end of the bearing shaft 2325 to promote alignment when assembling the bearing to the bearing shaft 2325.
For purposes of illustration and not limitation, various exemplary embodiments may include a diaphragm formed of rubbers (e.g., EPDM (ethylene propylene diene monomer) rubber, HNBR (hydrogenated nitrile butadiene rubber)). A spinner may include thermoplastics (e.g., POM (polyoxymethylene), PPS (polyphenylene sulfide)), PEI (polyethylenimine), Bronze 510, Oilite, POM with a wear additive, or a combination thereof. For lubrication, some embodiments may incorporate EM50L, petroleum lubricant, or no lubricant. In various embodiments, by way of example and not limitation, some implementations may include any of a hardened shaft, two or more ball bearings, and/or an extended length spinner.
In one illustrative example, an exemplary pump may include EPDM diaphragm, a POM spinner, and EM50L lubricant.
In another illustrative example, an exemplary pump may include an eccentric shaft fixed in the spinner and rotatably coupled to the wobble plate with a bearing at the top of the wobble plate's hole for the shaft. In an illustrative example, an exemplary pump may include EPDM or HNBR diaphragm, a POM spinner, a POM or POM with wear additive wobble plate, and EM50L lubricant.
In another illustrative example, an exemplary pump may include EPDM diaphragm, a POM with wear additive spinner, and EM50L lubricant.
In another illustrative example, an exemplary pump may include an EPDM or HNBR diaphragm, a Bronze spinner, and EM50L or petroleum lubricant.
In another illustrative example, an exemplary pump may include an extended height spinner, EPDM diaphragm, a POM, oil-impregnated POM, of PTFE (polytetrafluoroethylene)-impregnated POM spinner, and EM50L lubricant.
Some implementations may provide automatic self-lubrication and/or ejection of wear material.
In another illustrative example, an exemplary pump may include non-metal spinners with EM50L or petroleum lubricant and both diaphragm materials. Some embodiments may include a second ball bearing in the spinner hole or a hardened shaft. Various embodiments may include, for example, EPDM or HNBR diaphragm, a POM, PPS, or PE (polyethylene) spinner, and EM50L or petroleum lubricant, with a hardened shaft and two bearings.
In another illustrative example, an exemplary pump may include an oil-impregnated metal, such as Oilite. Some embodiments may include, for example, EPDM or HNBR diaphragm, Oilite spinner, and EM50L lubricant.
In another illustrative example, an exemplary pump may include an EPDM diaphragm, a POM spinner, and EM50L lubricant, with increased load surface achieved by increased eccentric hole, shaft and bearing diameter.
Although various embodiments have been described with reference to the Figures, other embodiments are possible. For example, in some embodiments noise may be reduced in systems that are designed for a maximum throughput greater than a predetermined specification corresponding to a specific application. The pneumatic pump may then be operated at a sub-maximal flow rate.
In some embodiments, the angle difference between the motor drive axle and the piston drive axle may affect operating parameters of the pump. For example, if the angle difference is small, the flow rate may be reduced and/or the lifetime may be increased. In some embodiments, if the angle difference is large, the flow rate may be increased, but at the possible expense of noise being increased and greater wear resulting in attenuated life. In some embodiments the angle difference may be between ten and fourteen degrees, for example.
The angle of the radial arm members relative to the shaft 1220 may also be varied. In some embodiments, an exemplary angle may generally approximate the angle between the motor drive axle and the piston drive axle. This angle generally allows for the arm 260 to reach a state perpendicular to the axis of the pump 255 that positions the piston so that the face of the piston 226 is in a parallel plane to the face of the cylinder head 227 at top dead center giving greater efficiency by evacuating a maximum amount of air from the cylinder in a compression stroke.
Various embodiments may use various materials for each of the pump components. For example, the piston drive member may be made of metal. For example, the piston drive member may be made of steel. In an exemplary embodiment, the piston drive member may be made of aluminum. In some embodiments, the piston drive member may be made of plastic. For example, the piston drive member may include Polyphenylene Sulfide (PPS) plastic. In an exemplary embodiment, the piston drive member may include Polyether Imide (PEI) plastic. In some embodiments, the piston drive member may include Polyoxymethylene (PEM) plastic. Some embodiments may include nylon plastic in one or more pump members, including the piston drive member.
In some embodiments, the intake manifold may be split into separate intake lines, each corresponding to a piston. This split intake manifold may minimize noise associated with intake of fluid.
Various embodiments may exhibit improved durability and service life when a canted off-axis drive is configured to reciprocate a number of pliable pistons operably connected to an equal number of radially arranged piston cranks, with an optimized Moment-Insertion Ratio (MIR) between (i) a radial moment arm of any one of the piston cranks and (ii) a shaft insertion depth into a canted off-axis driver bearing. In an illustrative example, the optimal MIR may yield substantially reduced wear and improved service life when the forces that the canted off-axis driver bearing imparts radially onto the shaft are substantially equal and opposite in magnitude. The radial moment arm may extend from an axis of the shaft to, for example, any of at least two linearly actuatable pliable-pistons. In some embodiments, each of the radially arranged piston cranks may be coupled to the shaft at a common point along the shaft.
In some embodiments, the drive shaft receptacle may be configured to prevent relative rotation between the spinner body and the drive shaft. The drive shaft receptacle may be keyed to correspond to and receive a non-cylindrical drive shaft with a corresponding key feature such that the spinner body rotates synchronously with the drive shaft. The drive shaft receptacle may have at least one flat side corresponding to each of at least one flat side of the drive shaft, for example. The drive shaft receptacle may rigidly couple to the drive shaft, such as by integral molding (e.g., dip molding or the like) to form the spinner to a drive shaft. In some examples, the drive shaft may provide a non-cylindrical surface, such as positive and negative surface features, to increase the torque capability of the molded spinner to the drive shaft. Some embodiments may employ a pin or set screw, for example, to secure the spinner body against rotation with respect to the drive shaft.
In various embodiments, a spinner, such as the spinners 2205 or 2310, for example, may nutate the wobble plate in response to the rotation of a drive shaft about a drive axis of rotation. In various examples, the longitudinal axis may be offset and canted with respect to a drive axis of rotation
A number of implementations have been described. Nevertheless, it will be understood that various modification may be made. For example, advantageous results may be achieved if the steps of the disclosed techniques were performed in a different sequence, or if components of the disclosed systems were combined in a different manner, or if the components were supplemented with other components. Accordingly, other implementations are contemplated to be within the scope of the following claims.
This application claims the benefit of U.S. Provisional Patent Applications Ser. No. 62/036,959, filed by Douglas, et al., on Aug. 13, 2014 and entitled “Canted Off-Axis Driver For Quiet Pneumatic Pumping,” and Ser. No. 62/171,725, filed by Douglas, et al., on Jun. 5, 2015 and entitled “Durable Canted Off-Axis Driver For Quiet Pneumatic Pumping.” The entire disclosures of each of the foregoing documents are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62036959 | Aug 2014 | US | |
| 62171725 | Jun 2015 | US |
