Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
  • F04C28/28—Safety arrangements; Monitoring
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
  • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
  • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
  • F04C18/0246—Details concerning the involute wraps or their base, e.g. geometry
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
  • F04C27/005—Axial sealings for working fluid

Definitions

• This invention relates in general to a fluid displacement device. More particularly, it relates to an improved scroll-type fluid displacement device which achieves a high built-in volume ratio without compromising other optimum design parameters. This invention also relates to a "semi-compliant" mechanism for maintaining the desired operative relationship between the scroll members of a scroll-type fluid displacement device.
• Scroll-type fluid displacement devices are well-known in the art.
• U.S. Pat. No. 801,182 to Creux discloses a scroll device including two scroll members each having a circular end plate and a spiroidal or involute scroll element.
• These scroll elements have identical spiral geometries and are interfit at an angular and radial offset to create a plurality of line contacts between their spiral curved surfaces.
• the interfit scroll elements seal off and define at least one pair of fluid pockets.
• the line contacts are shifted along the spiral curved surfaces, thereby changing the volume of the fluid pockets. This volume increases or decreases depending upon the direction of the scroll elements' relative orbital motion, and thus, the device may be used to compress or expand fluids.
• FIGS. la-Id schematically illustrate the relative movement of interfitting spiral-shaped scroll elements, 1 and 2, to compress a fluid.
• the scroll elements, 1 and 2 are angularly and radially offset and interfit with one another.
• FIG. la shows that the outer terminal end of each scroll element is in contact with the other scroll element, i.e., suction has just been completed, and a symmetrical pair of fluid pockets Al and A2 have just been formed.
• FIGS. lb-Id shows the position of the scroll elements at a particular drive shaft crank angle which is advanced from the angle shown in the preceding figure.
• the fluid pockets, Al and A2 shift angularly and radially towards the center of the interfitting scroll elements with the volume of each fluid pocket Al and A2 being gradually reduced.
• Fluid pockets Al and A2 merge together at the center portion A as the crank angle passes from the state shown in FIG. lc to the state shown in FIG. Id.
• the volume of the connected single pocket is further reduced by an additional drive shaft revolution.
• outer spaces which are shown as open in FIGS, lb and Id, change to form new sealed off fluid pockets in which the next volume of fluid to be compressed is enclosed (FIGS, lc and la show these states) .
• FIG. 2 diagrammatically illustrates the compression cycle that takes place in one of the fluid pockets, Al or A2, as it converges toward the center portion A.
• FIG. 2 also illustrates the relationship between fluid pressure and volume in the fluid pocket.
• the compression cycle begins (FIG. la) when the fluid pockets are sealed.
• FIG. la the suction phase has just finished.
• the fluid pressure in one of the fluid pockets in the suction phase is shown at point H in FIG. 2.
• the volume of the pocket at point H is the displacement, V H .
• the volume of the fluid pocket is continuously reduced and the fluid is continuously compressed as the scroll element is rotated to a certain crank angle. This state is shown by point L in FIG. 2.
• the volume (V L ) of the pocket at state L is defined as the final compression pocket volume.
• the fluid pockets, Al and A2 are connected to one another and simultaneously connected to the central volume A which is filled with undischarged high pressure fluid.
• the ratio of the suction pocket volume, V H to the final compression pocket volume, V L is defined as the built-in volume ratio, R v .
• the ratio of the pressure (P L ) at state L to the pressure (P H ) at state H is defined as the pressure ratio.
• the built-in volume ratio be designed as close to the ideal compression process as possible.
• Different applications require different built-in volume ratios to realize their respective ideal compression process.
• a heat pump would require a ratio of about 4
• an air compressor would require a ratio of about 5
• a low temperature refrigeration system would require a high ratio of about 10 or even higher.
• most conventional scroll devices cannot achieve these ratios.
• the spiral elements of the scroll members span more than two but less than three full turns.
• the built-in volume ratio for this type of design is only about 2.5.
• U.S. Patent No. 4,477,238 discloses one method for achieving a high pressure ratio in a scroll- type displacement device by leaving the built-in volume ratio unchanged and placing a discharge valve, for instance, a reed valve, at the discharge port.
• a discharge valve for instance, a reed valve
• FIGS. 15 and 16 of U.S. Pat. No. 801,182 disclose one example of this approach.
• the scroll elements span approximately four full turns, and the built-in volume ratio can reach higher than three. Further increase in the number of turns, however, will increase machining costs and machining precision requirements. Increasing the number of turns may also be extremely impractical due to displacement requirements or space limitations.
• the optimum number of turns for a scroll element is greater than two but less than three. With the optimum number of turns, the suction and discharge areas are always separated by at least one sealed off pocket. This is important in order to reduce the undesired leakage flow of both mass and heat between the two areas.
• U.S. Patent No. 3,989,422 discloses a method of constructing spiral-shaped scroll elements having a high built-in volume ratio and the optimum number of turns. According to this method, the first turn of the scroll element is designed in a conventional manner. In order to reduce the volume of the final compression pocket, and thus increase the built-in volume ratio, the scroll element suddenly and dramatically reduces its radius of curvature by moving the center of its generating circle toward one side. This method has serious shortcomings. As the central portion of the scroll element moves towards one side of its end plate, greater forces and moments are created due to the increased distance between the location where the compression forces act and the center of the end plate during its orbiting motion.
• the '422 patent provides a structure with multiple pairs of scroll elements in which the forces and moments cancel each other out.
• this structure increases machining time, machining precision requirements and material costs due to the complex structure and increased number of the scroll elements.
• the larger space requirements of the complex multiple scroll structure make it geometrically impractical to implement.
• the tip-seal scheme is shown in FIG. 10, and a further example is disclosed in U.S. Patent No. 3,994,636 to McCullough et al.
• a groove 501 is made in the middle of the tips of two scroll members, 502 and 503.
• a seal element 504 is loosely fitted in the groove 501 and urged by mechanical and/or hydraulic forces (not shown) into contact with the base 505 of the other scroll member, thus keeping fluid from leaking across the spiral scroll elements, 502 and 503, in the radial direction.
• the tip seal method inherently includes tangential leakage passages, as shown by lines A-A and B-B in FIG. 10, which reduce the compression efficiency.
• Other shortcomings of the tip seal method include friction power loss and the gradual deterioration of sealing effectiveness due to the seal elements wearing out.
• the fully axially compliant schemes have several shortcomings.
• the gas pressure used in these schemes is often derived from the compression pockets and/or the discharge chamber, and thus, may vary in accordance with changes in the operating conditions, i.e., the suction and discharge pressure.
• these changes are not always proportional to the separating forces acting on the tips and bases of the scroll members.
• the bias force is sufficient for a range of operating conditions about a particular point, it would not be enough to maintain stable operation at low suction pressure and low discharge pressure.
• the same bias force would be excessive for operating conditions at high suction pressure and high discharge pressure.
• U.S. Patent No. 4,958,993 to Fujio discloses a third approach to maintaining gaps between scroll members. This approach may be referred to as "semi- compliant" since the gaps between the scroll members in the axial direction may be enlarged by moving one scroll member away from the other.
• the ⁇ 993 patent teaches that the orbiting scroll member should be made movable in the axial direction, rather than the non-orbiting scroll member. This is done to keep the number of moving parts to a minimum since the orbiting scroll member is already movable and the non-orbiting scroll member is already stationary. Moving parts are a source of unwanted vibration and noise. Also, the orbiting scroll member is typically lighter than the non-orbiting scroll member, and thus the response time of the orbiting scroll member is quicker due to its smaller inertia.
• the potential for tipping the orbiting scroll member is greatly increased by making it movable in the axial direction.
• the orbiting scroll member is subject to a driving force, F d , acting on the middle of driving pin boss 53, and to a reaction force, F g , from the compressed gas acting on the middle of the vane 51.
• F d driving force
• F g reaction force
• the ⁇ 993 patent teaches a range of movements (orbiting and axial) for the orbiting scroll member which makes it extremely difficult to balance the forces and moments acting on the scroll member and thereby prevent it from tipping. If the x 993 patent's orbiting scroll member tips, it creates the same unwanted noise vibration and leakage that the x 993 design was intended to avoid.
• the present invention provides a new method of designing the scroll elements of a scroll-type fluid displacement device. Under the present invention, the design requirements for displacement, high built-in volume ratio and optimum number of turns are all satisfied.
• the present invention also provides an improved semi-compliant biasing scheme in which the potential for tipping is eliminated, thereby significantly reducing the amount of unwanted noise, vibration and leakage.
• the present invention eliminates the detrimental effects of friction power loss, vibration, noise and wear caused by frictional contact between the tips and bases of the scroll members.
• Another and more specific object of the present invention is to provide a novel construction for the scroll elements of a scroll-type displacement device wherein the scroll elements have the desired built-in volume ratio, displacement and number of turns, without causing significant unbalanced forces and moments or dramatically increasing of the complexity of the scroll elements.
• Still another object of the present invention is to provide a novel construction for a scroll-type displacement device wherein the scroll elements may have either identical or non-identical basic geometric configurations.
• the disclosed embodiment of the present invention provides a scroll-type fluid displacement device, which includes a housing having a fluid inlet port and a fluid outlet port.
• a first scroll member has an end plate from which a first scroll element extends axially into the interior of the housing.
• a second scroll member also has an end plate from which a second scroll element extends axially. The second scroll member is movably disposed for non-rotative orbital movement relative to the first scroll member.
• the first and second scroll elements interfit at an angular and radial offset to create a plurality of line contacts which define at least one pair of sealed fluid pockets.
• Drive means is operatively connected to the scroll members to effect their relative orbiting motion while preventing their relative rotation, thus causing the fluid pockets to change volume.
• the disclosed embodiments of the present invention provide a novel method for designing the geometric configurations of the internal and external surfaces of both scroll elements to achieve the desired displacement, built-in volume ratio and number of turns.
• the principles of the method are described as follows:
• the curvature of the inner portion of the first scroll element is also designed in any conventional manner such that the desired built-in volume ratio is satisfied;
• a second scroll element is designed by deriving the mathematical conjugate of the first scroll element.
• the second scroll element is interfit with the first scroll element at an angular and radial offset.
• the present invention is disclosed in connection with an air compressor in which the vane thickness and involute generating circle of both the outer and inner portions of the scroll elements are the same.
• the outer and inner portions of the scroll elements are constructed in a conventional manner to satisfy a given displacement and built-in volume ratio. They are then linked by an intermediate portion which has derivatives of zeroth and first order that are equal to the derivatives of the outer and inner portions at the junctions.
• the geometric configuration of the intermediate portion is chosen so that the optimum number of turns is achieved.
• continuous and smooth walls of spiral-shaped scroll elements are formed by respective outer, intermediate and inner portions, which provide the desired displacement, the desired built-in volume ratio and the optimum number of turns.
• the scroll elements are made of involute curves.
• the involute curves are geometrically identical and are developed from the same generating circle.
• each scroll element includes several portions of involute curves which are developed from different generating circles, and yet, the two scroll elements remain identical in terms of geometric configurations and substantially convergent to the center of the end plate.
• the two scroll elements are geometrically different from each other.
• the first and the second embodiments are identified below as “identical” and “non-identical. "
• the scroll-type fluid displacement device includes means for providing mechanical forces for urging two scroll members together in an axial operative relationship. At the same time, the potential for tipping the scroll members is eliminated and constant gaps are maintained between the extreme ends or tips of one scroll member and the base of the other scroll member.
• a scroll-type fluid displacement device in another aspect of the present invention, includes means for providing hydraulic forces for urging two scroll members together in an axial operative relationship. At the same time, the potential for tipping the scroll members is eliminated and constant gaps are maintained between the tips of one scroll member and the base of the other scroll member.
• a scroll-type fluid displacement device in another aspect of the present invention, includes a first non-orbiting scroll member which is movable in the axial direction.
• a second scroll member orbits about an axis, but is fixed linearly along this axis.
• the first and second scroll members are interfit, and the first scroll member is movably biased against the second scroll member such that the first scroll member will yield axially under sufficient force.
• the above-described scroll-type fluid displacement device includes a stabilizing mechanism for maintaining the first scroll member perpendicular to the axis of its scroll element, but movable along this axis in the rearward direction. At the same time, constant gaps are maintained between the extreme ends or tips of one scroll member and the base of the other scroll member.
• FIGS. la-Id are schematic views illustrating the relative orbital movement of the scroll elements in a conventional scroll compressor
• FIG. 2 is a pressure-volume diagram illustrating the compression cycle, including ideal compression, undercompression and overcompression;
• FIG. 3 illustrates the forces and moments acting on the orbiting scroll element
• FIG. 4 illustrates a cross section of a scroll-type air compressor constructed in accord with the present invention
• FIG. 5 illustrates a top cross-section view of a first embodiment of the present invention in which the scroll elements are substantially identical
• FIGS. 6a and 6b illustrate top cross-section views of a second embodiment of the present invention in which the scroll elements are substantially non-identical;
• FIG. 7 illustrates a conventional scroll element from which the first and second embodiments of the invention are developed;
• FIG. 8 illustrates the interfitting scroll elements of the first embodiment
• FIG. 9 illustrates the interfitting scroll elements of the second embodiment.
• FIG. 10 illustrates a typical structure for a conventional tip seal
• FIGS. 11a and lib illustrate cross section and top views of a first embodiment of the axial semi-compliant mechanism of the present invention
• FIGS. 12a and 12b illustrate cross section and top views of a second embodiment of the axial semi-compliant mechanism of the present invention
• FIGS. 13a and 13b illustrate cross section and top views of a third embodiment of the axial semi-compliant mechanism of the present invention.
• FIG. 14 illustrates a cross section and top view of a scroll-type air compressor with a semi-compliant scheme in which a gas, at discharge pressure, acts on the rear side of the first scroll member to provide an axial biasing force.
• the compressor unit 10 includes a main housing 20 and a compressor shell 21 having a front end plate 22 and a cup-shaped casing 23.
• the front plate 22 is attached to the compressor shell 21 in a known manner (e.g. welding) .
• the shell 21 and casing 23 are attached to the main housing 20, also in a conventional manner (e.g. welding or bolting) .
• the main housing 20 holds a main journal bearing 30.
• a main shaft 40 is rotatably supported by bearing 30 and rotates along its axis Sl-Sl when driven by an electric motor or engine (not shown) .
• a sealing element 41 seals the shaft 40 to prevent lubricant and air inside the shell from escaping.
• a drive pin 42 extrudes from the rear end of main shaft 40, and the central axis of drive pin, S2-S2, is offset from the main shaft axis, Sl-Sl, by a distance equal to the orbiting radius R or of the second scroll element.
• the orbiting radius is the radius of the orbiting circle which is traversed by the second scroll member 50 as it orbits relative to the first scroll member 60.
• the first scroll member 60 has an end plate 61 from which a scroll element 62 extends.
• the first scroll member 60 is attached to the main housing 20 in a manner which may be referred to as "semi-compliant." Using this method of attachment, the first scroll member 60 is perpendicular to the axis Sl-Sl and spring biased (by spring 70) against a surface 24 of the main housing 20. This assures that appropriate gaps, 65, are maintained between the tips of the scroll elements of one scroll member and the base of the end plate of the other scroll member.
• gaps should be wide enough to prevent the tips and bases of the scroll members from contacting each other after taking into consideration the manufacturing tolerances and thermal growth of the scroll elements during normal operation. On the other hand, the gaps must also be small enough to be sealed off hydrodynamically by a film of lubricant during normal operation.
• the first scroll member yields axially (as measured linearly along the center axes of the scroll elements) against the urging force of the spring bias 70 to prevent damage. This arrangement is referred to as "semi-compliant" and is more fully described later in this application.
• the first scroll member 60 includes a reinforcing sleeve 63 and ribs 64.
• the first scroll member 60 is capable of making an excursion rearward in the axial direction.
• the scroll element 62 is affixed to and extends from the front end surface of the end plate 61, and the reinforcing sleeve 63 and ribs 64 extend from the rear surface of the end plate 61.
• the second scroll member 50 includes a circular end plate 51, a scroll element 52 affixed to and extending from the rear surface of the end plate 51, and an orbiting bearing boss 53 affixed to and extending from the front surface of the end plate 51.
• Scroll elements 52 and 62 are interfit at a 180 degree angular offset, and at a radial offset having an orbiting radius R or . At least one pair of sealed off fluid pockets is thereby defined between scroll elements 52 and 62, and end plates 51 and 61.
• the second scroll member 50 is connected to a driving pin 42 (through a driving pin bearing 43) and a rotation preventing oldham ring 80.
• the second scroll member 50 is driven in an orbital motion at the orbiting radius R or by rotation of the drive shaft 40 to thereby compress fluid.
• the working fluid enters the compressor 10 from the inlet port 91, and is then compressed by the scroll members and discharged through discharge hole 92, passage way 93, chamber 94 and discharge port 95.
• the discharge gas is sealed off from chamber 96 by the bearing surface 54 between the pin bearing 43 and the pin bearing boss 53, and by a seal element 44.
• the discharge gas acts on the bottom surface 45 of the boss 53 to reduce the axial thrust force from the compressed fluid in the compression pockets during operation.
• Counterweights 97 and 98 balance the centrifugal force acting on the second scroll member 50 due to its orbiting motion.
• the scroll elements of the two scroll members have substantially identical configurations.
• An example of one such scroll element is shown in FIG. 5.
• the selected external surface spans less than a complete turn. Consequently, the volume of final sealed compression pocket, and thus, the built-in volume ratio of the first embodiment, will be slightly different from the base design shown in Figure 7. This will be taken care of later.
• An intermediate involute arcade surface spans 360 degree of involute angle from E 2 to E 3 with the radius of the generating circle calculated as follows: wherein R g and R gl are the radii of generating circles centered at O and 0 lf respectively as shown in FIG. 5. The generating circles O and 0- ⁇ share the same tangents at end points E 2 and E 3 of the external surfaces, respectively.
• an intermediate involute arcade surface spans 360 degree of involute angle from I- L to I 2 with the radius of the generating circle calculated as follows:
• R and R 2 are the radii of generating circles centered at O and 0 2 , respectively as shown in FIG. 5.
• the generating circles O and 0 2 share the same tangents at end points I ⁇ and I 2 of the internal surfaces, respectively.
• the second embodiment of the present invention is described herein as “non-identical” and shown in FIGS. 6a and 6b.
• the general design specifications are the same as the first embodiment.
• the second scroll element has uniform wall thickness, as shown in FIG. 6a. In comparison to the first embodiment, it is lighter in weight, and therefore causes less centrifugal force during its orbiting motion.
• the scroll element shown in FIG. 6a consists of three spiral portions. Both inner and outer portions are approximately a full turn of spiral wall - r> ⁇ - taken directly from the conventional scroll element shown in FIG 7. More specifically, in FIG. 6a, the external surface of the inner portion, K 2 L 2 K 3 , spans from a starting involute angle of 224 degrees to an ending angle of 583 degrees with a generating circle radius of 0.14324 inch. The external surface of the outer portion, KLK ⁇ , spans from a starting involute angle of 1303 degrees to the ending angle of 1663 degrees, with the same generating circle radius. The external surface of the intermediate portion, the involute surface K 2 L 1 K 1 , whose generating circle radius is
• the internal surface of the scroll element shown in FIG. 6a is parallel to its external surface, and the wall thickness (t) is approximately 0.2 inch.
• the scroll element shown in FIG. 6b is the mating conjugate of the scroll element shown in FIG. 6a, but they are not identical.
• the external surface of the second scroll element shown in FIG. 6b consists of three portions of spiral curves, i.e., MPM 2 , M 2 P 2 M 3 and M 3 P 2 M 4 .
• the intermediate portion 2 P*-_M 3 is an involute of the generating circle radius
• the internal surface of the scroll element shown in FIG. 6b also consists of three portions, NQN ⁇ N- ⁇ - ⁇ and N 2 Q 2 N 4 .
• the inner and outer portions span from a starting involute angle of 224 degrees to an ending angle of 763 degrees for the inner portion, and from a starting involute angle of 1483 degrees to an ending angle of 1663 degrees for the outer portion, respectively.
• the intermediate portion of the internal surface continuously and smoothly links the inner and the outer portions and shares the same generating circle with the intermediate portion of the external surface.
• FIG. 9 shows the two non-identical scroll elements interfit with each other during operation. Because of the intermediate portion, the volumes of the suction pockets and the final sealed compression pockets are slightly different from the specifications. It is easy to adjust this by slightly changing the spanning involute angle of the outer and/or inner portions of the internal and the external surfaces of the scroll elements. Due to the non-identical nature of the two scroll elements, the volumes of the pair of compression pockets, Al and A2, as shown in FIG. 9, differ from each other by a small amount which is not significant in most applications. The same situation happens to the volumes of the final compression pockets and the built-in volume ratios. To compensate for these differences, one can adjust the starting involute angle of the inner portion of the scroll element. Often, the deviation of the built-in volume ratio from the original specifications is not significant, and an adjustment is unnecessary.
• FIGS. 11-13 three embodiments of a semi-compliant mechanism made according to the present invention will now be described.
• the outer peripheral surface 160 of the end plate 61 of the first scroll member 60 has three equally spaced flat edges 161.
• Three positioning blocks 162 form a stabilizing mechanism which prevents the first scroll member from "tipping.”
• the blocks 162 are affixed to the main housing 20 by bolts 163.
• the blocks 162 fit tightly against the flat edges 161 of the end plate 61 such that the scroll member 60 remains perpendicular to the axis Sl-Sl, but can make axial excursions rearward under the guidance of blocks 162.
• the term "axial” is used herein to refer to linear movement along a particular axis, as opposed to rotational movement around a particular axis.
• the first scroll member 60 is urged by springs 70 towards the second scroll member 50 until it is stopped by the surface 24 of the main housing 20. This assures appropriate gaps 165 between the tip of one scroll member and the base of the other scroll member.
• the second scroll member 50 is also stabilized to prevent it from tipping.
• the stabilization mechanism for the second scroll member 50 is provided by the housing 20 which acts as a thrust bearing on one side of the end plate, and by the large gas pressure in the space between the scroll members, 50, 60.
• the gaps 165 must be sufficiently large to insure that there is no tip-base contact during normal operation.
• the gaps 165 must be sufficiently small that the leakage flow of the working fluid through the gaps is either insignificant in comparison to the fluid displaced or can be totally sealed off by lubricant film formed between the tips and bases of the scroll members during normal operation.
• a cast iron scroll compressor having a height in the axial direction of 2 inches would, under the disclosed design, call for a gap 165 of .0030 inches under cold conditions.
• the first scroll member 60 makes an axial excursion rearward until it is stopped by the limiting lip 164 of the positioning blocks 162.
• FIG. 12a and 12b illustrate a second embodiment of the present invention.
• the first scroll member 60 is stabilized and affixed to the main housing 20 by three stabilizing pins 261, which prevent the • first scroll member 60 from rotating or “tipping.”
• the first scroll member 60 is urged by springs 70 towards the second scroll member 50 until it is stopped by the surface 24 of the main housing 20. This assures appropriate gaps 265 between the tip of one scroll member and the base of the other scroll member.
• the first scroll member 60 will make an axial excursion rearward until it is stopped by the limiting lip 264 of the positioning blocks 262.
• the blocks 262 are secured to the main housing 20 by bolts 263.
• FIGS. 13a and 13b illustrate a third embodiment of the present invention.
• Three elastic positioning plates 361 are affixed to stabilizing blocks 362 by bolts 363.
• the blocks 362 are affixed to the main housing 20 by bolts 366.
• the plates 361 have slots 367, which tightly hold the ribs 64 of the first scroll member 60 to stabilize the first scroll member 60 and prevent it from rotating or tipping in a plane perpendicular to the axis Sl-Sl, but allowing it to make an axial excursion rearward due to the elasticity of the plates 361.
• the stabilizing blocks 362 tightly hold the first scroll member 60 at the edge 367 to prevent the first scroll member 60 from “tipping.”
• the first scroll member 60 is urged by springs 70 towards the second scroll member 50 until it is stopped by the surface 24 of the main housing 20. This assures appropriate gaps 365 between the tip of one scroll member and the base of the other scroll member.
• the first scroll member 60 makes an axial excursion rearward until it is stopped by the limiting lip 364 of the stabilizing blocks 362.
• FIG. 14 shows a cross section of a fourth embodiment of the present invention.
• the basic operating principles of this embodiment are the same as the device shown in FIG. 4.
• a discharge gas is employed to provide the axial biasing force.
• FIG. 14 illustrates a modified version of the compressor shown in FIG. 4, and these modifications are discussed below.
• Discharge gas is sealed off in a discharge chamber 496 by O-ring 497, and by providing close tolerance between sleeve 63 and lid 498.
• the sleeve 63 and lid 498 also provide an additional stabilization mechanism for the scroll members, 50, 60.
• Discharge port 495 is welded to lid 498 which is bolted to casing 23. Discharge gas exerts bias force on the rear surface 499 of sleeve 63. The area of surface 499 is chosen so that the bias force slightly exceeds the separating force acting on the front surface of the first scroll member 60 during normal operation.
• the first scroll member 60 is thus urged towards the second scroll member 50 and is stopped by surface 24 of the main housing 20 to ensure appropriate gaps 465 between the tips and bases of the two scroll members 50, 60.
• the stabilizing pins 466 prevent the first scroll member 60 from rotating in the plane perpendicular to the axis S i -S i and also prevent it from "tipping.”
• the first scroll member 60 yields rearward in the axial direction against the bias force until it is stopped by lip 464.

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• Engineering & Computer Science (AREA)
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• General Engineering & Computer Science (AREA)
• Rotary Pumps (AREA)

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• 1994
  • 1994-01-26 AU AU65320/94A patent/AU6532094A/en not_active Abandoned
  • 1994-01-26 WO PCT/US1994/001031 patent/WO1995020719A1/en active IP Right Grant
  • 1994-01-26 EP EP94912735A patent/EP0742869B1/de not_active Expired - Lifetime
  • 1994-01-26 DE DE69424803T patent/DE69424803T2/de not_active Expired - Lifetime
  • 1994-01-26 JP JP51105995A patent/JP3445794B2/ja not_active Expired - Fee Related

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