Patent Application
20140271242
1. Field of the Invention
The present invention relates to a scroll pump having a pump head/motor assembly that includes a stationary plate scroll having a stationary scroll blade, an orbiting plate scroll having a scroll blade nested with the stationary scroll blade, and a pump motor having a rotary output coupled to the orbiting plate scroll so as to drive the orbiting scroll blade relative to the stationary scroll blade. In particular, the present invention relates to a scroll pump having a system that reduces the noise and vibration produced by the pump head/motor assembly.
2. Description of the Related Art
A scroll pump is a type of pump that includes a stationary plate scroll having a stationary plate and a spiral stationary scroll blade projecting axially therefrom, and an orbiting plate scroll having an orbiting plate and a spiral orbiting scroll blade projecting axially therefrom. The stationary and orbiting scroll blades are nested with a clearance and predetermined relative angular positioning such that a pocket (or pockets) is delimited by and between the stationary and orbiting scroll blades. The stationary plate scroll is fixed in the pump. The orbiting scroll plate and hence, the orbiting scroll blade, is coupled to an eccentric driving mechanism. The stationary and orbiting plate scrolls and the eccentric drive mechanism may make up what is referred to as a pump head.
The eccentric drive mechanism is, in turn, connected to and driven by a motor of the pump such that the orbiting scroll plate orbits about a longitudinal axis of the pump passing through an axially central portion of the stationary scroll blade. The volume of the pocket(s) delimited by the scroll blades of the pump is varied as the orbiting scroll blade moves relative to the stationary scroll blade. The orbiting motion of the orbiting scroll blade also causes the pocket(s) to move within the pump head assembly such that the pocket(s) is selectively placed in open communication with an inlet and outlet of the scroll pump.
In an example of such a scroll pump, the motion of the orbiting scroll blade relative to the stationary scroll blade causes a pocket sealed off from the outlet of the pump and in open communication with the inlet of the pump to expand. Accordingly, fluid is drawn into the pocket through the inlet. Then the pocket is moved to a position at which it is sealed off from the inlet of the pump and is in open communication with the outlet of the pump, and at the same time the pocket is collapsed. Thus, the fluid in the pocket is compressed and thereby discharged through the outlet of the pump.
In the case of a vacuum-type of scroll pump, the inlet of the pump is connected to a chamber that is to be evacuated. Conversely, in the case of a compressor-type of scroll pump, the outlet of the pump is connected to a chamber that is to be supplied with pressurized fluid by the pump.
In any case, the rotary components of the pump head and motor produce vibrations. These vibrations, in turn, can generate sound waves, i.e., the rotary components can create a significant amount of noise. The vibrations can also be transmitted to other nearby equipment, resulting in reduced performance of that equipment.
It is a general object of the present invention to provide a scroll pump in which vibrations of a pump head/motor assembly of the pump are isolated from the exterior of the pump including the supportive base which the pump is resting on.
It is a more specific object of the present invention to provide a scroll pump that runs quietly.
It is another object of the present invention to provide a scroll pump which has a pump head/motor assembly supported by a vibration isolation system and yet which can be transported without the pump head/motor assembly being allowed to move relative to other components of the pump and potentially damage the components.
It is likewise another object of the present invention to provide a method by which a scroll pump, having a pump head/motor assembly supported by a vibration isolation system, can be transported without being damaged.
It is still another object of the present invention to provide a scroll pump having a system that can isolate vibrations of the pump head/motor assembly, and in which the movement of the pump head/motor assembly is restricted independently of the vibration isolation system so that adverse shocks will not damage components of the pump during operation.
According to one aspect of the invention, there is provided a scroll pump having a pump head/motor assembly, a sound-muffling enclosure in which the pump head/motor assembly is housed, feet that support the sound-muffling enclosure and which have bottom surfaces constituting the bottom of the pump, and a vibration isolation system comprising a set of elastic vibration isolators each having top and bottom ends, and in which the pump head/motor assembly is fixed to the vibration isolators at the top ends thereof so as to be integrated with the vibration isolators, the sound-muffling enclosure is fixed to the vibration isolators at the bottom ends thereof, and the pump head/motor assembly is attached in the pump to the sound-muffling enclosure via the vibration isolators. Therefore, the pump head/motor assembly is movable under the elasticity of the vibration isolators relative to the sound-muffling enclosure. Accordingly, the vibration isolation system isolates the sound-muffling enclosure from vibrations transmitted from the pump head/motor assembly.
According to another aspect of the invention, there is provided a scroll pump having a pump head/motor assembly, feet having bottom surfaces that constitute the bottom of the pump, a vibration isolation system to which the pump head/motor assembly is mounted, a sound-muffling enclosure interposed between the vibration isolation system and the feet such that the sound-muffling enclosure is also interposed between the pump head/motor assembly and the feet, and a selective locking system by which the motion of the pump head/motor assembly can be locked independently of the vibration isolation system to the sound-muffling enclosure, and by which the sound-muffling enclosure can be locked to the same support surface that the feet are resting on independently of the feet and without the pump head/assembly being locked to the sound-muffling enclosure such that the pump head/motor assembly is supported by the support surface only via the vibration isolation system.
Therefore, the pump can be placed in a first mode, in which the feet are resting against the support surface while the pump head/motor assembly is hard mounted to the sound-muffling enclosure such that it can not move relative to the sound-muffling enclosure.
The first mode may be a shipping mode. In the shipping mode the sound-muffling enclosure is also rigidly mounted to the support surface. If the pump is shipped as a self contained product, the support surface is typically a plywood base that forms the bottom of a shipping container. Alternatively the support surface may be a structural component of a larger piece of equipment when the pump is integrated and shipped, as an integrated component, with the larger piece of equipment.
In addition, the pump can be placed in a second mode in which the feet are resting against a support surface while the pump head/motor assembly is not locked to the sound-muffling enclosure and the sound-muffling enclosure is locked to the support surface independently of the feet. Accordingly, the sound-muffling enclosure can be hard mounted to the support surface such that it can not move relative to the support surface while the pump head/motor assembly is free mounted to the sound-muffling enclosure via the vibration isolation system such that the pump head/motor assembly can vibrate relative to the sound-muffling enclosure and support surface.
This second mode may be the operational configuration of the pump when it is an integrated component of a larger piece of machinery, i.e., the second mode may be what is referred to as an integrated component in operational mode. In this case, the support surface would typically be a structural surface within the larger piece of machinery. This mode allows the pump head/motor assembly to vibrate within the sound-muffling enclosure without transmitting vibrations to the equipment or noise to the operator of the equipment, while the pump is nonetheless securely fastened to the support surface in the equipment.
In addition, the pump can be placed in a third mode, i.e. bench top operational mode, in which the feet are resting against a support surface while the pump head/motor assembly is not locked to the sound-muffling enclosure. Accordingly, the sound-muffling enclosure is not hard mounted to the support surface and can be located and moved as required while the pump head/motor assembly is free mounted to the sound-muffling enclosure via the vibration isolation system such that the pump head/motor assembly can vibrate relative to the sound-muffling enclosure and supportive surface. This third mode would be the operational configuration of the pump when it is used as a stand-alone component not integrated as a component within a large piece of equipment. The supportive surface would typically be a table or bench top. This mode allows the pump head/motor assembly to vibrate within the sound-muffling enclosure without transmitting vibrations to the support surface or to the operator of the equipment, while allowing the pump to be easily portable. In this mode, the sound muffling enclosure would be supported via elastic feet by the support surface, i.e. table, further reducing transmitted vibrations.
According to still another aspect of the present invention, there is provided a vibration management method for a scroll pump having a pump head/motor assembly supported by a vibration isolation system within an enclosure. The method includes setting feet at the bottom of an enclosure of the pump atop a support surface such that a pump head/motor assembly of the pump housed within the enclosure is supported by the support surface only via the vibration isolation system, and either subsequently locking the pump head/motor assembly to the support surface independently of the vibration isolation system so that the pump can be transported along with the support surface in a state in which the pump head/motor assembly is prevented from moving relative to the support surface, or fastening the enclosure independently of the feet to the support surface while operating the pump in a state in which the pump head/motor assembly is supported by the support surface only via the vibration isolation system.
These and other objects, features and advantages of the present invention will be better understood from the detailed description of the preferred embodiments thereof that follows with reference to the accompanying drawings, in which:
Various embodiments and examples of embodiments of the inventive concept will be described more fully hereinafter with reference to the accompanying drawings. In the drawings, the sizes and relative sizes of elements may be exaggerated for clarity. Likewise, the shapes of elements may be exaggerated and/or simplified for clarity and ease of understanding. Also, like numerals and reference characters are used to designate like elements throughout the drawings.
Furthermore, terminology used herein for the purpose of describing particular examples or embodiments of the inventive concept is to be taken in context. For example, the terms “comprises” or “comprising” when used in this specification indicates the presence of stated features or processes but does not preclude the presence of additional features or processes. The term “pump” may refer to apparatus that drives, or raises or decreases the pressure of a fluid, etc. The term “fixed” may be used to describe a direct connection of two parts to one another in such a way that the parts can/do not move relative to one another or a connection of the parts through the intermediary of one or more additional parts in such a way that the parts can/do not move relative to each other.
Referring now to
The pump head 200 includes a frame 210, a stationary plate scroll 220, an orbiting plate scroll 230, an eccentric drive mechanism 240, an annular metallic bellows 250 and fasteners fixing the stationary plate scroll 220 to the frame 210 and the annular metallic bellows 250 to both the frame 210 and the orbiting plate scroll 230.
The stationary plate scroll 220 comprises a stationary scroll blade 221, and the orbiting plate scroll 230 comprises an orbiting scroll blade 231. The stationary scroll blade 221 and the orbiting scroll blade 231 are nested with a clearance and predetermined relative angular positioning such that a pocket or pockets is/are delimited by and between the stationary and orbiting scroll blades. In this respect, side surfaces of the stationary scroll blade 221 and the orbiting scroll blade 231 need not contact each other to seal the pocket(s). Rather, minute clearances between side surfaces of the stationary scroll blade 221 and the orbiting scroll blade 231 may create a seal sufficient for forming a satisfactory pocket(s).
The eccentric drive mechanism 240 includes a drive shaft and bearings 246. In this example, the drive shaft is a crank shaft having a main portion 242 coupled to the pump motor 300 so as to be rotated by the motor about a longitudinal axis L of the scroll pump 1, and a crank 243 whose central longitudinal axis is offset in a radial direction from the longitudinal axis. The bearings 246 comprise a plurality of sets of bearings having rolling elements.
Also, in this example, the main portion 242 of the crank shaft is supported by the frame 210 via one or more sets of the bearings 246 so as to be rotatable relative to the frame 210. The orbiting plate scroll 230 is mounted to the crank 243 via another set or sets of the bearings 246. Thus, the orbiting plate scroll 230 is carried by crank 243 so as to orbit about the longitudinal axis of the pump when the main portion 242 is rotated by the pump motor 300, and the orbiting plate scroll 230 is supported by the crank so as to be rotatable about the central longitudinal axis of the crank 243. The pump head 200 and the pump motor 300 connected to the main portion 242 of the eccentric drive mechanism 240 of the pump head 200 together constitute a pump head/motor assembly housed in the sound muffling enclosure 100.
Furthermore, the annular metallic bellows 250 has a first end at which the annular metallic bellows 250 is fixed to the back side of the orbiting plate scroll 230 and a second end at which the annular metallic bellows 250 is fixed to the frame 210. In this respect, the annular metallic bellows 250 is radially flexible enough to allow the first end thereof to follow along with the orbiting plate scroll 230 while the second end of the annular metallic bellows 250 remains fixed to the frame 210. On the other hand, the annular metallic bellows 250 has a torsional stiffness that prevents the first end of the annular metallic bellows 250 from rotating significantly about the central longitudinal axis of the annular metallic bellows 250, i.e. from rotating significantly hr its circumferential direction, while the second end of the annular metallic bellows 250 remains fixed to the frame 210.
The annular metallic bellows 250 may be essentially the only means of providing the angular synchronization of the stationary scroll blade 221 and the orbiting scroll blade 231 during the operation of the scroll pump 1. Moreover, not only does the annular metallic bellows 250 extend between the frame 210 and the orbiting plate scroll 230, but the annular metallic bellows 250 also extends around a portion of the crank 243 and the bearings 246 of the eccentric drive mechanism 240. In this way, the annular metallic bellows 250 may also seal the bearings 246 and bearing surfaces from a space defined between the annular metallic bellows 250 and the frame 210 in the radial direction and which space may constitute the working chamber C, e.g., a vacuum chamber of the pump, through which fluid worked by the pump passes. Accordingly, lubricant employed by the bearings 246 and/or particulate matter generated by the bearing surfaces can be prevented from passing into the chamber C by the annular metallic bellows 250.
Referring to
Moreover, the feet 510 are configured so as to be essentially rigid, especially in comparison to the elastic vibration isolators 500A. Furthermore, the pump head/motor assembly 200/300 is attached in the pump to the sound muffling enclosure 100 only through the elastic vibration isolators 500A so as to be movable (due to the elasticity of the vibration isolators) relative to the sound muffling enclosure 100. Therefore, the vibration isolation system 500 isolates the sound muffling enclosure 100 from vibrations transmitted from the pump head/motor assembly 200/300. Because the sound muffling enclosure 100 constitutes the exterior of the scroll pump 1, these vibrations are not imparted to the exterior of the scroll pump or the support surface. Hence, the transmitted noise and vibration produced by the rotary components of the pump head/motor assembly 200/300 is substantially reduced.
To increase this effect, the sound muffling enclosure 100 may be formed in part or in whole of a known type of sound-absorbing material (101 in
A more detailed explanation of the sound-muffling effect provided by the present invention will be described with reference to
The pump head/motor assembly 200/300, as a mass, is supported on the elastic vibration isolators 500A as springs. Thus, in this respect, the elastic vibration isolators 500A should be designed to damp the vibration of the mass. Specifically, the spring constant k of the elastic vibration isolators 500A should be such that the natural frequency measured in hertz of the mass supported by the springs (½ pi√k/m) is substantially less than lowest frequency of the vibrations that are expected to be produced by the apparatus. In the case of apparatus such as a scroll pump, the components that produce vibrations of the lowest frequency are the rotary components, i.e., the lowest frequency of vibrations typically corresponds to the lowest frequency of rotation ω of the rotary components, which in this case is the frequency of rotation of the pump motor 300. Thus, the vibration isolation system is configured such that the natural frequency of the mass (pump head/motor assembly 200/300) mounted on the isolators of spring constant k is less than the rotational frequency of the pump motor 300.
In this case, the elastic vibration isolators 500A will be effective in reducing the transmission of vibrations produced by the mass. However, although the lowest frequency of vibrations (e.g., ˜10-60 Hz) produced by the rotary components during normal operation of the pump produce falls below or near the range of audible frequencies, the operation gives rise to harmonics within the range of audible frequencies. Therefore, the elastic vibration isolators 500A may do little to prevent airborne noise produced by the vibrating mass (pump head/motor assembly 200/300) at the rotation rate. However, they can substantially reduce the transmitted noise at the higher harmonics.
As is clear from the description above, the sound muffling enclosure 100 is a surround for the vibrating mass. Furthermore, the sound muffling enclosure 100 remains stationary or will at most vibrate to a much lower degree than the mass because the sound muffling enclosure 100 is attached to the elastic vibration isolators 500A at what amounts to the stationary end of the springs constituted by the elastic vibration isolators 500A. Thus, the sound muffling enclosure 100 will not vibrate to produce any airborne sound itself, and will block or cause the sound waves produced by the mass (pump head/motor assembly 200/300) to attenuate, thereby muffling the sound produced by the mass.
In this embodiment, the sound muffling enclosure 100 comprises a cowling 110 and a tray 120. The tray 120 has a top and a bottom, and the elastic vibration isolators 500A are mounted to the tray 120 at the top thereof. The pump head/motor assembly 200/300 is supported by the tray 120 atop the elastic vibration isolators 500A, and the cowling 110 is detachably connected to the tray 120 at locations spaced from the elastic vibration isolators 500A. The cowling 110 may be made up of several parts to facilitate its ability to be secured to and removed from the tray 120.
A scroll pump according to the present invention not only includes the above-described means for suppressing noise that would otherwise be produced by the vibrating of components of the scroll pump 1, but may also include means for suppressing noise otherwise produced by the flow of the fluid worked by the pump and discharged through the outlet 100B.
Specifically, the scroll pump 1 may also include an internal muffler, in the version of the scroll pump 1 shown in
Next, a locking system for use in managing the vibrations and/or facilitating the transport of the pump in a safe way will now be described in detail.
Referring first to
Each locking fastener 540 includes a screw threaded to the pump head/motor assembly 200/300, and a motion arresting bracket 120B (referred to hereinafter as a “motion arrester”) integral with the sound muffling enclosure 100. More specifically, the screw has a head 546 having a polygonal opening therein, e.g., a square or hexagonal recess, a shaft 542 comprising a screw thread, and a stopper 544 molded to the shaft 542 adjacent the head 546 so as to be integral with the shaft 542. The head 546 and stopper 544 may, as shown in the drawings, be unitary, formed of plastic and molded to the shaft 542 such that the shaft extends from the head 546/stopper 544.
In addition, the pump head/motor assembly 200/300 has threaded openings 200/300T therein which receive the shafts 542 of the screws, respectively, such that the screws are threadingly engaged with and hence, carried by the pump head/motor assembly 200/300. Both the sound muffling enclosure 100 and the motion arrester 120B have openings therethrough axially aligned with a threaded opening 200/300T in the pump head/motor assembly 200/300, i.e., with the head 546 of the screw carried by the pump head/motor assembly 200/300.
Therefore, the screw can be rotated with a tool 525 (
In addition, in this embodiment, the motion arrester 120B has a recess in a side thereof facing the stopper 544. The recess in the stopper 544 and a side of the motion arrester 120B facing the recess have complementary shapes. In this example, at least part of the recess and part of the stopper 544 have complementary frusto-conical shapes.
Referring to
The operation and use of the locking system of the scroll pump according to the present invention will now be described with reference to
Basically, the pump head/motor assembly 200/300 can be locked independently of the vibration isolation system 500 to the sound muffling enclosure 100. In addition, the sound muffling enclosure 100 can be locked to the same support surface that the feet 510 are resting on independently of the feet and without the pump head/assembly 200/300 being locked to the sound muffling enclosure 100 such that the pump head/motor assembly 200/300 is supported by the support surface only via the elastic vibration isolators 500A of the vibration isolation system 500.
Accordingly, the scroll pump 1 can be placed using the locking system in a first mode in which the feet 510 are set against the support surface, the locking brackets 560 are set in the lowered position (phantom line position) shown in
Furthermore, the locking brackets 560 may be fastened to the support surface. The support surface may be a packing base, such as a sheet of plywood. In this case, the first mode is a shipping mode in which the pump can be transported, along with the packing base, in such a state that there is virtually no relative movement between the packing base, the sound muffling enclosure 100 and the pump head/motor assembly 200/300 despite the presence of the vibration isolation system 500 between the pump head/motor assembly and the sound-muffling enclosure. Alternatively the support surface may be a structural component of a larger piece of equipment when the pump is integrated and shipped, as an integrated component, with the larger piece of equipment.
In either case, the pump head/motor assembly will not contact and damage other components of the scroll pump 1 which are mounted to the sound-muffling enclosure, such as a cooling fan and/or a circuit board.
The scroll pump 1 can also be placed using the locking system in a second mode in which the feet 510 are set against a support surface, the locking brackets 560 are set in the lowered position (phantom line position) shown in
Furthermore, the locking brackets 560 are fastened to the support surface in the second mode. The support surface may be a working surface on which the pump is to be operated. The working surface may be the base of some larger machine. In this case, the second mode is a mode in which the scroll pump 1 can be operated while the sound muffling enclosure 100 is hard mounted to the support surface (i.e., can not move relative to the support surface) and the pump head/motor assembly 200/300 is free mounted to the sound muffling enclosure 100 via the vibration isolation system 500 (i.e., such that the pump head/motor assembly 200/300 can vibrate relative to the sound muffling enclosure 100).
Still further, the scroll pump 1 can be operated in a third mode in which the feet 510 are set against a support surface, the locking brackets 560 are set in the raised position (solid line position) shown in
Note, to place the pump in either of the second and third modes, the set screws may be turned (clockwise) until the stoppers 544 are disengaged from the motion arresters 120B, respectively, and abut the pump head/motor assembly 200/300). Despite the fact that the stoppers 544 are disengaged from the motion arresters 120B, the locking system may limit the range over which the pump head/motor assembly 200/300 can move (vibrate) relative to sound muffling enclosure 100 due to the fact that portions of the screws remain within the recesses of the motion arresters 120B. In this respect, the radial clearance between the screw and motion arrester 120B is set to allow for the pump head/motor assembly to vibrate up to its maximum amplitude (e.g., 0.5 mm) during normal operation of the scroll pump 1. Thus, the locking fasteners 540 may also constitute motion limiters that prevent the pump head/motor assembly 200/300 from vibrating abnormally relative to the sound-muffling enclosure, which could otherwise result in damage to the pump.
Finally, embodiments of the inventive concept and examples thereof have been described above in detail. The inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the embodiments described above. Rather, these embodiments were described so that this disclosure is thorough and complete, and fully conveys the inventive concept to those skilled in the art. Thus, the true spirit and scope of the inventive concept is not limited by the embodiment and examples described above but by the following claims.
