AU611970B2

AU611970B2 - Scroll machine

Info

Publication number: AU611970B2
Application number: AU25743/88A
Authority: AU
Inventors: James William Bush
Original assignee: Copeland Corp LLC
Current assignee: Copeland LP
Priority date: 1987-11-23
Filing date: 1988-11-21
Publication date: 1991-06-27
Anticipated expiration: 2008-11-21
Also published as: KR970001456B1; KR890008478A; DE3879887T2; BR8806152A; EP0318189B1; ES2034944T1; EP0318189A2; IN170806B; DE3879887D1; JPH0656081B2; CN1034413A; EP0318189A3; ES2034944T3; CN1012200B; AU2574388A; JPH01163401A; MX169843B

Description

611 970 COMMONWEA4LTH OF AUSTRALIA PATENTS ACT 1952 COWMP SPECOAMAlQ NAME ADDRESS OF APPLICANT: 0* 44 4 4 4 0440 4 .444 *4 44 400 40 40 4

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0 44 0~4 0 0 0 0 0 0 44 04 00 4 4 0 4*4000 0 0 0 4~44 40 0 4 0 400444 4 4 4 4 4 4 41 Copeland Corporation Campbell Road Sidney Ohio 45365 United States of America NAME(S) OF INVENTOR(S): James William BUSH ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Scroll Machine The following statement is a full description of this invention, including the best method of performing it known to me/us:-.

This invention relates to scroll-type ma~chines and more particularly to a scroll wrap configuration which reduces scrol-wrap noise and wear during operation of the machine.

Scroll machiLnes generally comprise mated first and second scroll mem'bers each having an end plate on which is provided an upstanding spiral wrap interleaved with the wrTap on the other scroll member; the w-aaps engaging 0 each other at substantially line contacts so as to define traveling pockets 0:0of varying volume as one scroll member is caused to orbit relative to the *0 other. The machine may be a pump coqpressor or expander.

0 00 0 ~oeain Some scroll machines have been found to have undesirable noise in 0 0 oprto.in trying to identify the noise it has been found that during manufacture, machinin~g forces can cause the outer free-end of one or both of Sthe spiral wraps to be deflected slightly radially outwardly. After 00 machining, the free end springs back to its original position thus presenting 0.0:a slightly misaligned projection which can cause undesirable engagement 0:0:between the respective scroll wraps during relative orbital movement.

Alternatively, when scroll wraps are machined into a solid surface with no 00free end on the wrap, tool deflection, rather than wrap deflection, can occur which has the same end result. This engaging contact not only can result in a banging noise but can contribute to wear of the scroll assembly, and possibly places additional loads on the crankshaft. Even if there is no distortion of the wrap end it is believed that this my be a relatively noisy area in the machine. Noise also can result from the sudden dynamic change in conditions at the point where the inner ends of the scroll wraps first lA communicate with the discharge port and/or separate from one another during operation.

The primary object of this invention therefore resides in the provision of a scroll-type machine which overcomes the aforementioned noise and wear problems in a simple and inexpensive manner which does not result in any significant loss of efficiency.

According to the present invention, there is provided a scroll type machine including :Oo ,first and second scroll members, each of said scroll members including 0 6 o 10 an end plate having an outwardly projecting spiral wrap thereon, each of said **goo So wraps having active flank surfaces and radially inner tip end portions, and s oouter and centre ports for receiving and discharging fluid, said wraps being a o interleaved with each other such that said active flank surfaces of said wraps interengage each other at a plurality of spaced locations so as to define a plurality of chambers therebetween such that when one of said scroll members is caused to orbit with respect to the other said scroll member said chambers will be caused to travel between said ports, whereby fluid received in one of said chambers through one of said ports is discharged through the other of said ports, characterised in the provision of means defining a first relieved surface in the outer flank surface of one of said wraps, said relieved surface extending circumferentially inwardly along said flank surface from a point which is just circumferentially outwardly of the outer end of said flank surface on the other 6 .of said wraps which except for said relieved surface would be an active flank surface and a ramp surface extending radially outwardly between the circumferentially inner end of said relieved surface and the adjacent active ,flank surface on said one wrap, said ramp surface extending circumferentially a distance substantially greater than the radial depth of said relieved surface.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: FIGURE 1 is a fragmentary vertical section view of the scroll assembly of a hermetic scroll-type compressor embodying the principles of the present invention; t ,'9 L,,90807,c sdaL004,copelanddspe, -i i i I i-i -2a- FIGURE 2 is a rotated section view taken generally along line 2-2 of Figure 1; and FIGURES 3 and 4 are enlarged fragmentary portions of Figure 2 showing in an exaggerated form the outer ends of the functional portions of the wraps.

Although the principles of the present invention may be applied to many different types of scroll-type machines, the discussion herein relates to a hermetic scroll-type machine including a pair of interfitting spiral vanes of equal shape (involutes of a circle) with one being non-orbiting and the other 10 being orbitally driven by a crankshaft, which machine has specific utility in the compression of refrigerant for air conditioning and 49 9, 9* 9 a 9too e9s a 0 6 .9 9 99

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I 4I 44 *4 9 9c 9 949 so 9 A'17i 990807,csdat.04,copeand.spe,2 refrigeration. A machine of the present type is disclosed in -assignee's our pcetf applicf'ioA No. 7733f/?7 7 Scroll-Type Machine, the disclosure-s expressly incorporated herein An exemplary embodiment of a scroll compressor 10 according to the present invention comprises a scroll assembly 12 for compressing gases, a motor (not shown), a vertically disposed crankshaft including at one end thereof a crank pin 14 for drivingly interconnecting the scroll assembly to the motor via a drive bushing 15, a compressor body 16, and a shell 18 o enclosing all of the above elements. The scroll assembly 12 includes an a 0 a°q orbiting scroll member 20 including a scroll end plate 22 and a scroll wrap "o 24 of desired flank profile an involute of a circle) upstanding o therefrom, and a non-orbiting scroll member 26 including a scroll end plate 00 0 °o o 28 and a scroll wrap 30 of similar flank profile upstanding therefrom, compressor body 16 supporting orbiting end plate 22 via the usual thrust o. surface 31. The scroll assembly also includes a central discharge port 32 in 0 00 S" non-orbiting end plate 28, a similarly shaped fluid transfer recess 33 in S orbiting scroll end plate 22 and a suction inlet port area 34.

S a .The effective ends of wraps 24 and 30 are disposed on diametrically opposed axes and respectively, with the end of wrap 24 indicated at 36 and the end of wrap 30 at 38 (this wrap is continued outwardly and circumferentially to define a suction passage but this continued portion does not act as a wrap because it never engages the orbiting wrap). The inner end of non-orbiting wrap 30 is indicated at 40 and the inner end of orbiting wrap 24 is indicated at 42.

dtermitied In accordance with this invention it has been diseevered that the benefits sought can be obtained if the outer surface of each wrap is relieved i'*

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f 3 7" 00 $,0 4 09 0 0 0 0 0~ 0 0 9900 00 00 0 009 O 00 op 0 090 0 00 0 0 00 0 00 in the area thereof where it would otherwise be engaged by the outer end of the other wrap. As shown, orbiting wrap 24 has a portion of its radially outwardly facing surface adjacent its radially outer free end 36 cut away or relieved to define a mo~dified offset surface 50 staring at point at the free end of the wrap and extending approximtely 1800 to 1900 toe point "B" (just past axis arnd then a ramp surface 52 tapering at a constant rate radially outwardly (approximately 200 from point to a point "C" whereupon the wrap surface assumes its normal involute shape. Phantom line (Figure 4) represents the outer flank surface of orbiting wrap 24 without being relieved in accordance with the present invention.

Similarly, non-orbiting wrap 30 has a mocdified offset surface extending approximately 8 0to 9 0between points and and a ramp surface 62 tapering at a constant rate radially outwardly approximately 20 0 to 21 0 from point to a point the latter representing the point where wrap 30 is back to its original profile and thickness. Phantom line "H" (Figure 3) represents the outer involute flank surface of nonorbiting wrap without being relieved in accordance with this invention.

Moified surfaces 50 and 60 are easily formed by merely offsetting the wrap-machining cutter very slightly radially inwardly 0.04 rmm in a scroll having an orbiting wrap roughly 85 mmr in overall outside diameter) to generate an offset surface parallel to the normal involute surface. Leakage is minimal because the offset is so small and because this is a relatively low pressure zone in the machine.

it has been learned that additional benefits can be obtained by also relieving the wraps near the inner ends thereof. Thus, orbiting wrap 24 has a portion of its radially inwardly facing flank surface adjacent its radially inner free end 42 cut away or relieved to reduce wrap thickness.

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0 0* 00 0 0 90 0 00 0 000040 0 0 000000 0 0 440900 9 0 00 0 0 90

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The removed portion defines a mo~dified surface 64 which tapers at constant rate radially outwardly from a point "ill to a point Similarly, non-orbiting wrap 30 has a portion of its radially inwardly facing flanik surface adjacent its radially inner free end 40 cut away to reduce wrap thickness, the removed portion defining a modxified Surface 66 wiich tapers at constant rate radially outwardly from a point to a point Points "J" and "Lm are located at a point disposed on the wrap flank surfaces slightly radially outwardly of the point of normal separation of the wraps, preferably at the point that discharge port 32 and recess 33 are opened. The :1 0 configuration of the discharge port 32 (and corresponding recess 33) is Sdisclosed in detail in assignee's application entitled Scroll Machine Center Por t filed of even date in the name of Gary J. Anderson, the disclosure of Swhich is expressly incorporated herein by reference. Points and "mN" are.

0:located slightly radially inwardly of the normal separation point of wraps if they had true involute flank surfaces. The resulting ramps, which are shown 0 iW in greatly exaggerated form, smooth the transition from loading to unloading of the wrap ends. Leakage is not a problem in the ramped area because the ~:discharge port is already opened.

Mod if ying the flank surfaces in the manner described has been found to reduce noise and wear, and it is believed that it will also allow the manufacturing process to be less precise and/or faster, and thus less expensive.

Miile it will be apparent that the preferred emnbodiments of the invention disclosed are well calculated to provide the advantages above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

Claims

1. A scroll type machine including first and second scroll members, each of said scroll members including an end plate having an outwardly projecting spiral wrap thereon, each of said wraps having active flank surfaces and radially inner tip end portions, and outer and centre ports for receiving and discharging fluid, said wraps being interleaved with each other such that said active flank surfaces of said wraps interengage each other at a plurality of spaced locations so as to define a plurality of chambers therebetween such that when one of said scroll members 9 r fis caused to orbit with respect to the other said scroll member said chambers N will be caused to travel between said ports, whereby fluid received in one of SO said chambers through one of said ports is discharged through the other of said 09 o o ports, characterised in the provision of means defining a first relieved surface in the outer flank surface of one of said wraps, said relieved surface extending circumferentially inwardly along said flank surface from a point which is just circumferentially outwardly of the outer end of said flank surface on the other of said wraps which except for said relieved surface would be an active flank o surface and a ramp surface extending radially outwardly between the circumferentially inner end of said relieved surface and the adjacent active flank surface on said one wrap, said ramp surface extending circumferentially a distance substantially greater than the radial depth of said relieved surface.

2. A machine as claimed in claim 1, wherein said active flank surfaces have complimentary profiles, said relieved surface being radially inwardly offset and parallel to said profile.

3. A machine as claimed in claim 2, wherein said profile is the involute of geometric shape.

4. A machine as claimed in claim 3 wherein said shape is a circle.

5' 90007,csdat.004,copeland.spe,6 -2 -7- A machine as claimed in claim 2, wherein said active flank surfaces have identical profiles.

6. A machine as claimed in claim 1, wherein said ramp surface extends radially outwardly at a constant rate of change.

7. A machine as claimed in claim 1, wherein both of said wraps have said relieved surface.

8. A machine as claimed in claim 1 further comprising means defining a second relieved surface, said second relieved surface being disposed on the inner flank surface of one of said wraps adjacent the inner tip end thereof at O the point of theoretical tip separation for the wrap active flank profile, said 0 .0 second relieved surface hav;.ig a portion extending radially outwardly from said wrap surface. 0o

9. A machine as claimed in claim 8, wherein said surface portion extends radially outwardly at a constant rate of change.

10. A machine as claimed in claim 1 further comprising means defining a 0o°r^ second relieved surface, said second relieved surface being disposed on the inner flank surface of one of said wraps adjacent the inner tip end thereof at i the point at which the outer surface thereof first becomes exposed to the pressure of fluid in said centre port during operation of said machine.

11. A machine as claimed in claim I further comprising means defining a second relieved surface, said second relieved surface being disposed on the inner flank surface of one of said wraps adjacent the inner tip end thereof and extending approximately from the point of theoretical tip separation for the wrap active flank profile to the point at which the outer surface thereof first becomes exposed to the pressure of fluid in said centre port during operation R'.1 -n ft T 910320,csdat137,copeland.let,7 !i of said m 1 iI-I--~ achine. I

12. A machine as claimed in claim 8, wherein both of said wraps have said second relieved surface.

13. A machine as claimed in claim 1, wherein said relieved surface extends through an arc of between 28 and 30 from said point.

14. A scroll type machine substantially as hereinbefore described with reference to the accompanying drawings. 0 #0e0 *00 boo 0 40 0 00a 0 00 DATED this 20th day of March, 1991. COPELAND CORPORATION By its Patent Attorneys: DAVIES COLLISON i I i 0 o a D 0 a 0 0 0 0 0 #4 0 0 0 4 4 tt a 4 4 t. 4 4 41 t .i 910320,csdat.137,copelanle 8