WO1989012730A1

WO1989012730A1 - Scroll fluid device using flexible toothed ring synchronizer

Info

Publication number: WO1989012730A1
Application number: PCT/US1989/002573
Authority: WO
Inventors: John E. Mccullough; Niels O. Young
Original assignee: Arthur D. Little, Inc.
Priority date: 1988-06-20
Filing date: 1989-06-13
Publication date: 1989-12-28
Also published as: EP0377730B1; EP0377730A1; US4911621A; CA1304260C; JPH03500912A

Abstract

A scroll fluid device is provided with a toothed ring synchronizer coupled to sprocket teeth provided on each scroll wrap back plate. The coupling between the teeth does not restrict relative axial motion between the scroll wraps and evenly distributes torque loads resulting from forces tending to rotate one wrap relative to the other between the back plates. The ring synchronizer may include internal or external teeth cooperating with adjoining sprocket teeth provided on the scroll back plates.

Description

SCROLL FLUID DEVICE USING FLEXIBLE TOOTHED RING SYNCHRONIZE

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

This invention is in the field of scroll fluid devices wherein mesh involute scroll wraps move in orbital fashion relative to each other to effe energy transfer by positive fluid displacement in chambers generated betwe the scroll wraps during operation of the device

DESCRIPTION OF PRIOR ART

The generic term "scroll fluid device" is applied to the well-kno arrangement of meshed, involute spiral wraps that are moved along curviline translation paths in orbiting fashion relative to each other to produce o or more fluid transporting or working chambers that move radially betwe entrance and exit zones of the device. The scroll devices may functi as pumps, compressors, expanders, or motors, depending upon the configuration, the drive system, and the nature of energy transfer betwe the scroll wraps and the fluid moving through the device.

Scroll devices, including their principle of operation, are fully describ by way of example in the following U.S. patents: No. 3,874,827 to Ni

O. Young; No. 3,560,119 to \V. Busch et al.; and No 4,141,677 to Weav et al. The descriptions contained in the aforementioned patents, to t extent that they generally describe the theory of operation and typic structural arrrangements of scroll fluid devices is herein incorporated reference. In scroll fluid devices, it is usually imperative that the scroll wrap be maintained in an established phase relationship in respect of their angula orientation relative to each other. Essentially, once the wraps are meshe in an established or desired position in which the involute wraps are dispose in a certain relative angular position relative to each other, this positio must be maintained during the operation of the scroll device to maintai sealing contact between wrap flanks (sidewalls) and to maintain the desig configuration of the fluid chamber that effects positive displacement o fluid moving through the scroll device (if a pump) or that constitutes th working chamber of the device (if a motor). While minor excursions fro the design set point may be tolerated in some designs, generally, the relativ angular position of the scroll wraps must be maintained during the operatio of typical scroll fluid devices.

In the prior art, the relative angular orientation of the scroll wrap is maintained typically by Oldham couplings that maintain the meshed scro wraps in torsionally coupled relationship that permits relative orbit movement while restricting relative rotation between the wraps. Th aforementioned patents describe typical Oldham couplings.

A problem encountered in prior art devices is that typical Oldha couplings are often imprecise, require lubrication under higher loads an speeds of operation, and they are subject to rotational imbalances whe the scroll wraps are co-rotated together as a spinning unit.

While some approaches have been taken in the prior art to elimina such disadvantages, typically the solution leads to other disadvantage including complexity, structurally weaker designs, or restrictions again certain degrees of movement of the scroll wraps that might be desired necessary for optimized performance of the device.

BRIEF SUMMARY OF THE INVENTION

The present invention contemplates using a flexible synchroniz in the form of a ring, belt or hoop element coupled by teeth or the equivale to the scroll wrap back plates, with the latter being provided with sprock teeth or the equivalent coupled to the synchronizer teeth.

The coupled synchronizer and sprocket teeth are periodically engag as one scroll orbits relative to the other scroll so that teeth wear is distribut fully around the synchronizer ring. Moreover, numerous teeth can be coup at any one time to distribute the torque load between scroll wraps eve along the length of the synchronizer ring.

Essentially, the scroll wraps are provided with sprocket teeth spa about a locus of symmetry about the base center of the involute wrap each scroll half. Generally, the sprocket teeth will be located in a cir around the periphery of a circular back plate of each scroll wrap. The num of teeth, their pitch, size and shape all are selected in accordance w those design parameters that will optimize the coupling between synchronizer and the scroll wraps, as well as effect the smooth trans of torque loads between the wraps.

The synchronizer ring, configured as a belt or flexible ring, is provid with ring teeth that engage and cooperate in coupling relationship w sprocket teeth associated with the back plates of the scroll wraps. Depend on design objectives, the synchronizer may be located inside of the sproc teeth and include external ring teeth, or may be located on the exter of the sprocket teeth with internal ring teeth engaging the sprocket teeth.

Forces tending to cause rotation of one wrap relative to the ot are reacted through the ring teeth and sprocket teeth so as to be transferr between the wraps via the synchronizer to thereby prevent relative rotati between the wraps.

Various other details of the invention and specific embodiments same will be evident from reading the ensuing detailed description and viewi the appended illustrations. DESCRIPTION OF THE DRAWINGS

Figure 1 is an elevational cross-section schematic view of a co-rotat scroll fluid device in cross-section incorporating the ring synchroni according to the invention, with the synchronizer having internal te coupling elements; Figure 2 is a bottom plan view of Figure 1 ;

Figure 3 is a detailed view of an area 3 of Figure 2;

Figure 4 is an end view of Figure 1 taken along line 4-4;

Figure 5 is similar to Figure 1 and shows the synchronizer ring appl to a single orbiting scroll device with an alternate configuration of te coupling elements; Figure 6 is a detailed view taken along line 6-6 of Figure 5;

Figure 7 is similar to Figure 1 showing an alternate synchronize arrangement used with a single orbiting scroll device;

Figure 8 shows a scroll device using a ring synchronizer with externa teeth coupling elements; and Figure 9 is a view taken along line 9-9 of Figure 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference to the drawings, and in particular with referenc to Figures 1, 2, 3 and 4, a scroll fluid device 10 is illustrated schematicall and includes co- rotating scroll wraps 12, 14 mounted for rotation abou axes of rotation 16, 18, the axes intersecting the base centers 20, 22 o involute wraps 12, 14, in accordance with known principles as describe in the aforementioned patent literature. The scroll wraps 12, 14 are supporte by back plates 24, 26 which in turn are driven in rotation about axes, 1 18, by motor 28 or other appropriate driving means. This is a typic arrangement for a co-rotating scroll compressor, with energy input bein supplied by a motor 28. Typically, upon rotation of motor 8 being imparte to an input drive shaft 30, fluid admitted at intake area 32 is radiall transported by at least a single pocket or chamber defined by the cooperatin meshed involute wraps 12, 14 and discharged through outlet 32 which i in communication with the central area 34 of the meshed, axially extendin wraps 12, 14. Since the wraps are supported for co-rotation about space parallel axes 16, 18, the wraps will also move relative to each other (i. orbit) along curvilinear translation paths about an orbit center, all as describe in the various patent literature previously mentioned.

The illustration of Figure 1 is exemplary only for a typical scro compressor, and it will be understood that various driving arrangemen could be utilized so that the scroll device operates as a pump, compresso expander or motor, depending upon the effect to be obtained by the transf of energy between the scroll wraps and the fluid moving through the devic For example, the motor 28 could be eliminated if pressurized fluid we admitted through the outlet duct 32 in a reverse direction and exhaust through the area 32, whereby the system would operate as a motor by t transfer of energy from the compressed fluid to the scroll wraps. The present invention is concerned with a synchronizer for maintain the scroll wraps 12, 14 in a predetermined geometric relationship where once an angular relationship is established between the wraps, it does substantially change while the system is operating. In the prior art, Oldh couplings are typically used for this function although other synchroni arrangements have been utilized.

In accordance with the present invention, sychronization betwe the wraps 12, 14 is maintained by a flexible synchronizer ring 36 that coupled, in accordance with the preferred embodiment, with the wrap suppo 24, 26 by coupling elements that are broadly termed "teeth" for reas that will become more evident in the ensuing discussion. In its simpl form, the synchronizer ring 36 is flexible, substantially inextensible, a extends in a belt or hoop-like fashion so as to span cooperating coupli "teeth" provided around the peripheries of the back plates 24, 26 (see Figu 2-3). As best illustrated in Figure 3, ring 36 is provided with teeth-li indentations 38 around its inner periphery, the indentations 38 cooperati with similar "teeth" 40 that axially project from the back plates 24, in interdigited relationship in accordance with this embodiment. The te 40 include male protrusions or ridges 42 that directly cooperate with t teeth 38 of ring 36 so as to form a direct driving relationship between t back plates 24, 26 and ring 36. Since the teeth 40 will typically drive t ring 36, for convenience the teeth 40 are termed "sprocket" teeth so t the driving relationship can be readily envisioned from the descriptive te "sprocket". However, it should be understood that the invention is not limit to a situation where the sprocket teeth perform the driving function betwe the wraps, since energy input to the scroll device could be applied throu the ring 36 by a suitable power or gear arrangement (not illustrated).

The synchronizer ring teeth elements 38 cooperate with the sproc teeth 40 to maintain the back plates 24, 26 in alignment with each ot in a rotational sense. Any forces tending to rotationally displace one b plate with respect to the other is reacted through the sprocket and r teeth elements from one back plate to the other to prevent relative rotat between the back plates. The flexibility of the synchronizer ring 36 perm it to be bent out of round sufficiently to accommodate the relative orbi movement between the back plates, while the inextensible characteris of the synchronizer ring prevents displacement of the sprocket teeth o one back plate in a rotational sense with respect to the sprocket teeth o the other back plate.

The arrangement of ring and sprocket teeth is usually selected s that there are more ring teeth than sprocket teeth. However, the synchronize ring theoretically could have the same number of teeth couplings as provide by the sprocket.

Generally, it is preferred to avoid overturning moments on the rin synchronizer 36 by locating the synchronizer in the same plane as the wrap 12, 14, with the sprocket teeth 40 interdigited or overlapping in an axi sense. However, and this will be described later, the sprocket teeth 4 conceivably could be axially spaced apart without changing the principl of operation of the invention. Preferably, the number of ring teeth element 38 is greater than the number of sprocket teeth means 40-42, with th difference in the number being equal to or greater than unity. Howeve it will be understood that any conceivable arrangement of a coupling syste that would function in the same manner as the illustrated teeth elemen would function to obtain the objective of the invention. Essentially, th critical requirement is that the ring synchronizer 36 must not interfer with the axial influences between the back plates 24, 26 so as not to distur the axial setting or freedom of movement of the wraps 12, 14. Thus, is desirable to have axially extending teeth such as illustrated, whereb the ring synchronizer 36 is free to float somewhat axially without limiti axial travel between the scroll wraps. Of course, any suitable motion limit can be provided to prevent the synchronizer ring 36 from traveling beyo the teeth 40 or the back plates 24, 26. A suitable snap ring (not illustrate or pin (not illustrated) could be provided in each back plate to limit t degree of axial movement of the synchronizer ring 36. However, duri operation, the ring 36 does not interfere with axial displacement or positio of the wraps 12, 14. Moreover, it will be noted that the synchronizer ri arrangement does not require reaction of torque loads into a housing other fixed structure to prevent relative rotation between the wraps 1 14. Rather, all influences tending to rotate one wrap relative to the oth are reacted between the back plates through the synchronizer so as maintain the same relative angular orientation between the wraps in a simp yet precise manner. It will also be observed that centrifugal forces are inherently balanc using a synchronizer such as the synchronizer ring 36. Unlike complex Oldha couplings constructed in accordance with the prior art, the system inherently balanced in rotation due to its symmetrical construction. addition, lubrication is essentially unnecessary, since synchronizer a sprocket ring teeth materials can be selected to be self-lubricating. Sin there is little relative movement between the sprocket and ring teet lubrication generally is not considered to be problematic.

In accordance with an alternate embodiment of the invention, seen in Figures 5 and 6, a synchronizer ring 50 having cylindrical tee elements 52 is arranged to cooperate with cylindrical, pin-like teeth 5

56 which respectively axially project towards each other from back plat

58, 60 in a scroll device including an orbiting wrap 62, a fixed wrap 64, a their associated back plates 58, 60. The orbital movement of scroll 6 of course, as in typical scroll devices, is about an orbit axis "0" that intersec the base center of the orbiting scroll wrap 62 to produce a fluid transf chamber or pocket between the wrap that moves radially between an inl zone 70 and an outlet zone 71 when the orbiting wrap is moved relati to the fixed wrap about orbit radius R₀. In accordance with this embodiment, the sprocket teeth are configur as circular pins 54, 56 extending axially from the fixed and orbiting ba plates 58, 60 in interdigited or overlapping relationship.

As seen in Figure 6, the synchronizer ring teeth elements compri recesses and projections upon the inner periphery of the ring. The recess 52 are likewise circular in configuration to match the external configurati of the pins 54, 56.

In all embodiments of the ring synchronizer, the spacing or pit of the ring synchronizer teeth is selected to cooperate with the relati orbital movement between the scroll wraps and the scroll back plates. In the embodiment of Figure 5, the orbiting scroll back plate 60 m be driven by a motor 28 through a drive shaft 66 provided with an eccentr crank 68 which drives the orbiting back plate 60 about an orbit radius R Upon actuation of motor 28 and rotation of drive shaft 66, orbiting scr wraps 62 are driven relative to fixed scroll wraps 64 to cause fluid admitt through intake zone 70 to be radially transported to outlet 72 in accordan with known principles governing the operation of scroll fluid devices. In accordance with an alternate embodiment as illustrated in Figur 7, the synchronizer element is shown in the form of a flexible belt or hoo 74 that is substantially inextensible along its length yet free to fle transversely of its circumferential length. In this instance, the synchronize 74 extends axially for a sufficient length to engage both back plates 76 78 of a co-rotating scroll fluid device having an input drive shaft 80 drive by motor 82 and a fluid outlet 84 receiving compressed or transported flui from intake zone 86. The same synchronizer 74 could just as well be utilize in a single orbiting scroll device wherein back plate 76 would be fixed agains rotation and input shaft 80 would be provided with crank means to caus orbital motion of back plate 78 relative to back plate 76. In the embodimen of Figure 7, the sprocket teeth extend around the periphery of the bac plates and axially between the plates without overlap. The number o synchronizer and sprocket teeth may be selected to achieve the desire coupling between the synchronizer 74 and the back plate 76, 78. Another alternate embodiment of the synchronizer is illustrated i

Figures 8 and 9, wherein the synchronizer is in the form of a ring gear hoop element 88 having external synchronizer teeth as illustrated best i Figure 9. In this embodiment, co-rotating scroll wrap back plates 90 an 92 are provided with axially extending, interdigited sprocket teeth 94, 9 that engage synchronizer teeth 98 in cooperating, coupling relationshi

In this embodiment, the fluid device is configured as a co-rotating compress with back plates 90, 92 supporting scroll wraps (not illustrated) that transf fluid from a radially outer zone 100 to a central area outlet 102.

The synchronizer ring element 88 with external teeth has the advanta that centrifugal forces keep the teeth 98 of the synchronizer clear contamination that otherwise might gather in the recess between t projections forming the synchronizer teeth. In addition, centrifugal loa can be taken up in this embodiment by the sprocket teeth 94, 96 whi generally will be made of metal or other rigid material while the synchroniz 88 can be made of a more yieldable material, for example a suitable plast resin. The resin may be selected from appropriate plastic compounds, f example, a thermoplastic such as nylon, which will tend to creep radial outwardly under the centrifugal loading of operation of the co-rotating fl device to compensate for wear in the external teeth area. In all of the embodiments illustrated, it is assumed that the scr wraps are based upon an involute generated from a base circle, althou conceivably other involute configurations could be accommodated by th synchronizer of the present invention. Essentially, the sprocket teeth nee to be spaced appropriately about a locus of symmetry about the base cente of each wrap to permit proper engagement between the sprocket teeth an the synchronizer teeth. The circumferential spacing between the sprocke teeth may be selected to accommodate the various loads transmitted throug the synchronizer coupling and the configuration of the teeth themselve may take virtually any form that will result in transfer of forces and couplin between the scroll wraps that would otherwise tend to cause relative angula displacement between the wraps. The teeth could be configured in the shap of gear teeth, wedges, circular pins, etc. Moreover, the teeth could be fin or coarse, depending on expected loads and other design consideration However, the coupling between the synchronizer and the scroll wraps wi always permit minor axial excursions between the scroll wraps and th synchronizer itself without rigid constraints and the number o sprocket/synchronizer teeth can be selected to evenly distribute the we on all the synchronizer teeth.

The synchronizer element may be formed of a single material possessin the appropriate characteristics of radial flexibility across its thickness an inextensibility along its circumferential length, or a composite materia for example metal/elastomer, and preferably the teeth are formed of material that is relatively more yieldable than the sprocket teeth with whic they are coupled. For example, the sprocket teeth could be formed of met while the synchronizer teeth could be formed of an elastically yieldabl plastic resin that permits good coupling between the teeth while still resistin relative angular deflection between the scroll back plates. The yieldabl synchronizer teeth accommodate wear, run more quietly than unyieldin teeth and do not require lubrication.

For a typical scroll device including a pair of scroll wraps spinnin on parallel axes separated by an orbit radius, the spacing t between be teeth centers can be calculated as follows: t = 2R₀/(N₂-N ₁) = 2 ₀/M (1) where: t = teeth pitch R_Q = orbit radius N2 = numbers of synchronizer ring teeth N = number of sprocket teeth m = N2-N1 The ring tooth pitch or spacing t is also related to the diametral pitch P as follows:

P =J#t (2)

The sprocket diameter D may be calculated from its diametral pitch P and the number of teeth N as follows:

D = N/P (3) In general, n can be any small integer, either positive or negative in sign. When external sprockets are synchronized by an encircling synchronizer having N2 teeth meshing with sprocket teeth of N , m is positive.

It is to be understood that various other physical embodiments o the invention can be formulated in accordance with principles that are wel known to those skilled in the art without departing from the spirit and scop of the invention as defined in the claims that follow.

Claims

WHAT IS CLAIMED IS:

1. A scroll fluid device comprising:

At least one pair of meshed axially extending involute spiral wraps defining at least one chamber between them that moves radially between an inlet zone and an outlet zone when one wrap is orbited by translation along a curvilinear path about an orbit center relative to the other wrap; wrap support means secured to and supporting each wrap; means for mounting the wrap support means for relative orbital motion relative to each other; synchronizer means for preventing relative rotation of one wrap relative to the other notwithstanding the orbital motion of one relative to the other; said synchronizer means including a plurality of sprocket teeth means affixed to each wrap support means said sprocket teeth means spaced about a locus of symmetry about the base center of each wrap; and a flexible, ring synchronizer element spanning said sprocket teeth means and including a plurality of ring teeth elements in coupled relationship with said sprocket teeth means; whereby forces tending to cause rotation of one wrap support means relative to the other are reacted through the ring teeth elements and the sprocket teeth means and transmitted between the wrap support means to thereby prevent relative rotation between the wraps.

2. A scroll fluid device as claimed in claim 1, wherein one of said wraps is fixed and said means for mounting the wrap support means includes means for enabling the other wrap to orbit relative to the fixed wrap about said orbit center.

3. A scroll fluid device as claimed in claim 1 , wherein said means for mounting the wrap support means includes means for enabling both wraps to co-rotate about parallel axes separated by a distance corres¬ ponding to an orbit radius centered about said orbit center.

4. A scroll fluid device according to any one of claims 1, 2 or 3 wherein said ring synchronizer element comprises a hoop element with ring teeth elements spaced circumferentially around the inner periphery of the hoop element.

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5. A scroll fluid device as claimed in any one of claims 1, 2 or 3, wherein said ring synchronizer element comprises a hoop element with ring teeth elements spaced circumferentially around the outer periphery of the hoop element.

6. A scroll fluid device as claimed in claim 5, wherein said sprocket 0 teeth means comprise pin elements each having a circular profile.

7. A scroll fluid device as claimed in claim 6, wherein said hoop element includes sprocket teeth engaging notches having circular profiles for receiving said sprocket teeth means, said notches disposed between the ring teeth elements.

5 8. A scroll fluid device as claimed in any one of claims 1, 2 or 3, wherein said wrap support means comprises circular back plates, said wraps being disposed between the back plates, and said sprocket teeth means being disposed along the outer periphery of the back plates.

9. A scroll fluid device as claimed in any one of claims 1, 2 or 3, 0 wherein said wrap support means comprise back plates, said wraps being disposed between the back plates, and said sprocket teeth means extending axially towards each other between the back plates in interdigited relationship.

10. A scroll fluid device as claimed in any one of claims 1, 2 or 3, 25 said synchronizing element comprising a belt member.

11. A scroll fluid device as claimed in claim 10, said belt member including integrally molded ring teeth elements.

12. A scroll fluid device as claimed in claim 1 , said synchronizer element comprising a hoop element, with at least said ring teeth elements being formed from an elastically yieldable plastic resin.

13. A scroll fluid device as claimed in claim 5, wherein said synchronizer element comprises a hoop element and wherein said ring teeth elements are formed from unfilled molded thermoplastic resin.

14. A scroll fluid device as claimed in claim 1, wherein the number of ring teeth elements is greater than the number of sprocket teeth means, with the difference in the number being equal to or greater than unity.