Co-rotating scroll compressor

Abstract

A scroll compressor includes a first scroll and a second scroll disposed within a housing. The first scroll defines a first involute extending from a first scroll base and receives a second involute extending from a second scroll base. A shaft is fixedly attached to the first scroll base and defining central shaft axis being coaxial with the first scroll and parallel to a second scroll axis. The shaft is received through a central opening defined by the second scroll base. A bearing hub includes an annular wall that is pivotally received by the central opening defined by the second scroll base. The bearing hub defines a bearing hub axis and an annular wall axis being offset from the bearing hub axis and the shaft axis. The shaft provides pivotal movement to the first scroll and to the second scroll relative to the bearing hub and the annular wall.

Description

CO-ROTATING SCROLL COMPRESSORCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to United States Provisional Patent Application No. 63 / 604,770 Filed on November 30, 2023, the contents of which are incorporated in entirety by reference.TECHNICAL FIELD

[0002] The present application relates generally to scroll compressor. More specifically, the present application relates toward an improved co-rotating scroll compressor useful for Heating, Ventilation, and Air Conditioning (“HVAC”) systems and vehicle thermal management systems.BACKGROUND OF THE INVENTION

[0003] Scroll compressors have been used to operate HVAC systems efficiently for many years. Most commercially successful scroll compressors have implemented a fixed scroll in combination with the orbiting scroll due to the simple mechanical interaction between the two scrolls. While these compressor designs have performed well since implementation, further improvements related to efficiency and vibration are desirable, particularly when implemented in, for example, HVAC systems of electric vehicles.

[0004] It has been thought that implementing co-rotating scrolls in which both scrolls are rotated by a driving shaft will provide significant efficiency and vibration improvements over more conventional scroll compressor designs. Efforts have been made to implement co-rotating scrolls in which cooperating scroll involutessimultaneously rotate along parallel but offset axes resulting in the necessary orbital motion between the individual scroll involutes. However, scroll compressors that implement co-rotating scroll technology has typically required multiple rotary bearings that can compromise reliability and efficiency in addition to adding manufacturing excessive cost. Moreover, scroll compressors have required pressure bearing to exert force on one or both of the scroll end plates to prevent axial scroll separation and tipping, however a higher force to control tipping is required in a corotating scroll compressor and co-rotating scroll compressors have required pressure bearing. This addition significantly increases the compressors power consumption and is known to considerably reduce reliability.

[0005] Scroll devices used for either compression or decompression (sometimes referred to as expansion scroll devices) of fluid requiring management of the forces resulting from the fluid that is trapped in the chambers formed between the scroll involutes continues to be a challenge. The forces generated by the trapped fluids include an axial separation force component due to fluid pressure on scroll end plates and a radial separation force on the scroll involutes themselves, vary cyclically as the scroll elements rotate. These fluctuating forces are influenced by two factors, the instantaneous location of the compression chambers formed by the scroll involutes during each revolution relative to the center of each scroll, and the actual pressure of the compressed fluid that also varies based on instantaneous location of the compression chamber in which the fluid is contained.

[0006] These factors collectively generate a torque load or moment in both axial and radial directions of each scroll. The net moment on the scroll, which is thecumulative effect of the torque loads developed in each compression chamber acts perpendicularly to the axis of rotation of the scroll causing the scroll to tip. Tipping is more pronounced at various locations on the scroll during rotation but may not occur at other locations resulting in a rocking or nutation of the scroll during rotation.

[0007] Conventionally, this issue has been addressed by applying an axial force to compress the end plates of each scroll together and by using relatively large bearings to counteract separating fluid forces adding mass and cost to the compressor. These compressive axial forces are typically induced either mechanically by implementing pressure bearings or by fluid pressure imposed on the opposite side of each scroll end plate. However, some of these methods are known to lead to considerable friction and power usage that adversely affects the efficiency of the compressor. Hence, there are often unnecessarily high pressures acting upon each scroll involute tip during a scroll cycle generating unnecessary friction and wear in addition to the excessive power consumption. The result has been a loss of overall efficiency as well as high axial loading which must be overcome during compressor startup. Each of these issues have resulted in inability to widely implement co-rotating scrolls.

[0008] Therefore, a need exists to mitigate tipping forces inherent in prior art corotating scroll compressors providing a more balanced assembly while simultaneously not requiring complexity and additional mass previously attempted.SUMMARY OF THE INVENTION

[0009] A scroll compressor assembly includes a first scroll and a second scroll disposed within a housing. The first scroll defines a first involute extending from a first scroll base and the second scroll defines a second involute extending from asecond scroll base. The second involute is received by the first involute. As used herein, involute means a spiral wall extending from a compression side of each scroll. A shaft is fixedly attached to the first scroll base and defines a central shaft axis that is coaxial with the first scroll and parallel to the central axis of the second scroll. The shaft is received through a central opening defined by the second scroll base. A bearing hub includes an annular wall that is pivotally received by the central opening defined by the second scroll base. The bearing hub defines a bearing hub axis and an annular wall axis that is offset from the bearing hub axis and the central shaft axis. The shaft provides pivotal movement to the first scroll and in cooperation with the guide pins that, pivotal movement the second scroll relative to the bearing hub and the annular wall. As such, rotation of the central shaft in cooperation with the guide mechanisms rotates the first and second scrolls on their respective axis relative to each other. This generates compression pockets between the cooperating involutes, which progressively decrease in volume and increase in pressure as the gas moves along the involutes from the inlet end of the involutes to the discharge end of the involutes.

[0010] The scroll compressor of the present invention substantially reduces the creation of net or unbalanced compression forces that result in unwanted tipping of the axis defined by the shaft as explained hereinabove. Thus, increased axial compliance forces are no longer necessary for a co-rotating scroll. The first scroll defines a first involute extending from a first scroll base and a shaft is fixedly attached to the first scroll base and defines a central shaft axis that is coaxial with the first scroll, extending from the free side of the driver scroll. The central shaftalso extending in the opposite direction through the base of the first or driver scroll compression side, beyond the scroll involutes. This arrangement allows for a bearing structure on both sides of the first scroll and for the load to be simply supported, eliminating the overturning moment.

[0011] This structure also allows for sufficient oil supply to the outboard bearing. The second scroll features a bearing structure that includes a bearing hub integral with the discharge end of its involute. The planar center of the second or idler scroll and the involute walls is coplanar with its bearing center. Rotation of the drive shaft in cooperation with the guide mechanism rotates the first scroll and the second scroll on their respective, common axis. This configuration generates compression pockets between the scroll bases and the two involutes. This progressively decreases in volume and increases in pressure as the involutes oscillate between the suction ends and the discharge ends of the scrolls.

[0012] Thus, a novel bearing and shaft structure is incorporated into both scrolls that is designed to eliminate the laterally directed tipping forces often encountered by scrolls in conventional co-rotating scroll compressors. This is achieved through implementation of a bearing hub that is integrated with the discharge end of the involutes of the second scroll and the shaft and bearing arrangement of the first scroll. The novel features of the scroll compressor of the present invention is anticipated to, for the first time, enable the benefits of co-rotating scrolls to be implemented in an economic and durable manner.BRIEF DESCRIPTION OF DRAWINGS

[0013] Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description, when considered in connection with the accompanying drawing, wherein:

[0014] Figure 1 shows a schematic of a refrigeration system of the present invention;

[0015] Figure 2 shows a side sectional side view of a co-rotating scroll;

[0016] Figure 3 shows a second sectional side view of the co-rotating scroll;

[0017] Figure 4 shows an isometric view of the upper frame;

[0018] Figure 5 shows an isometric, sectional view of the first and second scroll;

[0019] Figure 6 shows an isometric view of the free side of the second scroll;

[0020] Figure 7 shows an isometric view of the compression side of the second scroll;

[0021] Figure 8 shows an isometric view of the compression side of the first scroll;

[0022] Figure 9 shows an expanded isometric view of the compression side of the first scroll and the drive shaft;

[0023] Figure 10 shows a side sectional view of the first scroll and drive shaft;

[0024] Figure 11 shows a side sectional view of the first scroll and drive shaft rotated ninety degrees from the view shown in Figure 10; and

[0025] Figure 12 shows an exploded isometric view of the scrolls and drive shaft.DETAILED DESCRIPTION OF THE INVENTION

[0026] Referring to Figure 1, a scroll assembly of the present invention is generally shown at 10. A scroll compressor 12 includes a wall 14 having a tubularconfiguration in which components required to operate the scroll compressor 12 are enclosed and will be explained further herein below. Configurations of a housing other than tubular in which the components are disposed are also within the scope of this invention. Discharge line 16 receives fluid, i.e., refrigerant via discharge aperture 18 to transfer the fluid to a conventional condenser 20. The condenser 20 expels heat from the assembly 10 and condenses the refrigerant from vapor to liquid in a normal manner. The condenser 20 is fluidly connected to an expansion device 22 via a connecting line 24. The expansion device 22 takes the form of a thermally or electrically actuated valve controlled by an appropriate controller, a capillary tube assembly, or any other suitable device capable of expanding the refrigerant disposed within the assembly 10 in a known manner. A second connecting line 26 fluidly connects the expansion device 22 to an evaporator 28. Heat is absorbed within the evaporator 26 causing the liquid refrigerant to evaporate into a vapor form also in a conventional manner. Vapor refrigerant is returned to the scroll compressor 12 from suction line 30 via inlet 19 in which the refrigerant is subject to compression.

[0027] It should be understood by those of ordinary skill in the art that the compressor assembly of the present invention functions in a conventional manner adopting the principles of thermodynamics that are well known in the art. However, the components disposed within the scroll compressor 12 provide improvements over known systems as will be explained further hereinbelow. It should be further understood multiple scroll compressors 12 may be implemented within the assembly 10 either in parallel or in series and be interconnected with a plurality of condensers 20 and evaporators 28 to achieve desired thermodynamic results. Furtherexplanation on the thermodynamic properties of a conventional compressor assembly will not be described herein.

[0028] Referring now to Figures 2 and 3, the novel scroll compressor 12 of the present invention will now be explained. The wall 14 is enclosed by a upper portion 32 and a lower portion 34 that seal the tubular wall 14 to define a hermetic or semi- hermetic housing that provides a sealed enclosure. A frame 36 is secured within the tubular wall 14 of the scroll compressor 12 by either pressure fit, welding, or equivalent so that the frame 36 is fixedly attached to the wall 36. The frame 36 includes a frame bearing 38 that pivotably receives a drive shaft 40.

[0029] A motor 42 is disposed within the scroll compressor 12 and includes a stator 44 and a rotor 46. The drive shaft 40 is received by the rotor 46 so that the rotor provides pivotal motion to the drive shaft 40 around a shaft axis in a known manner. An annular gap 48 is defined between the stator 44 and the rotor 46 allowing friction free rotation to be imparted upon the rotor 46 by the stator 44 and allowing fluid to flow between the rotor 46 and the stator 44 within the gap 48.

[0030] A first (drive scroll) scroll 50 is fixedly attached to the drive shaft 40 orientated so that a scroll axis is coaxial with the shaft axis. Alternatively, the first scroll 50 is a monolithic construction with the drive shaft 40. Therefore, it should be understood that the first scroll 50 pivots with the drive shaft 40 when the drive shaft 40 is driven by the motor 42. The first scroll 50 includes a first scroll base 52 including a first scroll free side 54 and a first scroll compression side 56. The drive shaft 40 thusly extends away from the free side 54 toward the motor 42 in a perpendicular orientation to the free side 54. The central bearing 38 receives thedrive shaft 40 allowing the drive shaft 40 to pivot relative to the central frame 36 when driven by the motor 42.

[0031] The drive shaft 40 extends through the motor 42 and is received by lower bearing 58. It should be understood by those of skill in the art that the lower bearing 58 is an option element to the scroll compressor 12 and is not critical to eliminate tilt. The central bearing 38 and the lower bearing 58 that defines a central axis of a lower frame 59 for maintaining orientation of the drive shaft 40 so that the drive shaft axis remains at constant angle. The drive shaft 40 extends through the first scroll base 52 and is received by an upper bearing 60 that is interconnected with an upper frame 62 that is secured to the tubular wall 14 of the scroll compressor 12. The upper bearing 60 allows for low friction pivotal movement of the drive shaft 40 relative to the upper frame 62. Thus, the drive shaft 40 axis is maintained by the combination of the central bearing 38 and the upper bearing 60. This arrangement eliminates the propensity for a lateral tipping moment typically experienced by a drive scroll in a co-rotating scroll compressor.

[0032] A first scroll involute 64 extends from the first scroll compression side 56 defining a involute configuration. A second scroll (idler scroll) 66 defines a second scroll free side 68 and a second scroll compression side 70. A second scroll involute 72 extends from the second scroll compression side 70 and defines an involute configuration that is cooperably received by the within the involute configuration of the first scroll involute 64. Therefore, the first scroll involute 64 is received by the second scroll involute 72 when the first scroll 50 is mated with the second scroll 66.The first scroll 50 and the second scroll 66 define a compression chamber 74 in which the first scroll involute 64 and the second scroll involute 72 are disposed.

[0033] The drive shaft 40 defines a suction gas path 76 that opens to an upper chamber 77 of the upper portion 32 of the scroll compressor 12. The suction gas path 76 fluidly connects the upper chamber 77 to a low pressure side of the scroll involutes 64, 72 via a low pressure passage 78 defined by a shaft aperture 80 in the side of the drive shaft 40. A first scroll aperture 82, and defined by the first scroll base 52 leads the low pressure portion of the scroll involutes 64, 72 and is located at relatively outwardly of the first scroll base 52. Fluid flows from the chamber 77 through the suction gas path 76 toward the scrolls toward low pressure passage 78 via the shaft aperture 80. The fluid flows from low pressure passage 78 through the first scroll aperture 82 into the low pressure refrigerant inlet of scroll involutes 64, 72.

[0034] The second scroll 66 defines a second scroll bearing bore 90 that receives bearing 91 that eliminates the propensity for a lateral tipping moment typically experienced by the second scroll 66 in a co-rotating scroll compressor. The planar center of the second scroll involute 72 is coplaner with its center bearing 91.

[0035] As best shown in Figure 4, the upper frame or end plate 62 that is secured in a fixed position relative to the tubular wall 14 defines an endplate shaft 84 that extends toward the second scroll free side 68. The endplate shaft 84 includes an upper bearing bore 86 and an eccentric section 88 that are received by first scroll shaft bearing 60 and second scroll bearing 91.

[0036] The eccentric section 88 defines an eccentric axis that is offset from the drive shaft axis in a parallel orientation to the drive shaft axis. Aan upper bearing 60 receives the drive shaft 40 allowing the drive shaft 40 to pivot relative to the upper frame 62. As alluded to above, the second scroll base 67 defines a cylindrical bore 90 that is oriented substantially perpendicular to the second scroll compression side 70 for receiving the eccentric section 88 of the endplate shaft 84.

[0037] In order to manage the axial separation force component generated by the trapped fluids generated in the scroll involutes an annular flexible seals 96a and 96b are arranged in concentric annular grooves 97a and 97b defined by the second scroll free side 68 of the second scroll base 67. The periphery of the seal walls in combination of the free side of the second scroll base 67, and thrust plate 94, define the intermediate pressure chamber 92. An intermediate pressure fluid passage 99 allows fluid to enter the intermediate pressure chamber 92 for permitting fluid communication between the compression pockets formed by involutes of the first scroll 50 and second scroll 66. The pressurized fluid that is disposed within the intermediate pressure chamber 92 counteracts tipping forces on the scrolls 50, 66. The size and volume of the fluid passage 99 and the intermediate pressure chamber 92 are selected to provide necessary biasing force to counteract the tipping forces. A compression chamber discharge outlet 101 (Figure 6) allows discharge gas to exit the involutes 64, 72 and enter high pressure chamber 105 by way of passage 103 created by clearance between pressure plate and end plate shaft 84. It will be readily apparent to those skilled in the art that alternative means or configurations would be equally suitable for application in the subject invention.

[0038] A first scroll base 52-defines an extension member 102 that abuts and is fixedly attached to the pressure plate 94. A plurality of pins 104 are pressed into pockets 107 defined by the face of the pressure plate 94. The pins 104 extend from the face of the pressure plate in the direction of the second scroll 66. These pins 104 are positioned in a geometric circle, the centerline of which is concentric with that of the first scroll 50. Correspondingly, there are an equal number cylindrical pockets 108 defined by the second scroll free side 68 that receive the pins 104. These pockets 108 are placed on a geometric circle that is concentric with the centerline of the second scroll 66 and include a diameter that is greater than the diameter of the pins 104. This arrangement synchronizes the rotation of the first scroll 50 and second scroll 66 when rotated by the drive shaft 40. However, because the pins 104 float within the larger diameter pockets 108, the second scroll 66 is allowed to “float” relative to the pressure plate 94 to establish relative eccentric movement relative to the first scroll 50 all while being pivoted by the shaft 40. While in this embodiment, pins 104 are fixed in the pressure plate 94 and the holes or pockets 108 are in the second scroll 66, this configuration could be reversed. The holes or pockets 108 could be placed in face of the pressure plate 94 and the pins 104 could be placed in the free side of the second scroll 34.

[0039] An Oldham coupling could also be used to transmit toque and synchronize the first and second scroll. The Oldham coupling is positioned in between the free side of the second scroll 66 and the pressure plate 94 and includes a first pair of keys slidingly engaging slots in the second scroll and a second pair of keys slidingly engaging slots in the pressure plate. It is believed that the general principles of usingan Oldham coupling in a scroll compressor are well understood in the art, and that detailed explanation or embodiments of the mechanism and requirements for adapting an Oldham coupling does not need to be discussed further.

[0040] The rotation of the first scroll 50, in conjunction with the guide pins 104 engaged in the back of the idler scroll 66, allows both scrolls to rotate about their respective axes relative to each other. This generates compression pockets between their bases and involutes. These pockets progressively increase in pressure as they move along the involutes from their inlet ends to their discharge ends. Extension member 102 may be secured to the pressure plate 94 in any manner including, but not limited to welding. Therefore, it should be understood that the involutes 64, 72 are disposed between the pressure plate 94 and the first scroll end base 52.

[0041] Therefore, a fixed rotational relationship and is established between the first scroll 50 and the second scroll 66 so that the axial rotation of the drive shaft 40 corotates the first scroll 50 and the second scroll 66 in unison. However, the eccentric section 88 on the end plate 62 provides an eccentric axis of rotation to the second scroll 66 relative to the first scroll 50. Thus, the relative motion between the first scroll involute 64 and the second scroll involute 72 generate pressure pockets progressively increasing in pressure as the fluid disposed between the first scroll involute 64 and the second scroll involute 72 is forced radially inwardly until the high pressure fluid is discharged through the aperture 101 defined in the base 67 of second scroll 66.

[0042] As best represented in Figure 11, the shaft includes an oil bore 110 that distributes oil from an oil pick up 112. The oil bore 110 extends in a longitudinaldirection of the shaft 40 and is parallel to the suction gas path 76. The oil pick up 112 is bored into the lower distal end 114 of the shaft 40 that receives lubricating oil from an oil reservoir for distribution to the bearings 38, 58, 60.

[0043] Oil / lubricant is supplied to various scroll compressor components, including guide pins, bearings and other compressor parts through the oil bore 110. Oil / lubricant is conveyed from a sump 116 in the lower portion of the compressor through oil pick up 112. Rotation of the shaft 40, which includes hole 114 machined to receive an oil pickup tube (not shown) and oil bore 110, creates centrifugal oil pumping action that causes oil to be drawn from the sump 116 and delivered upwardly through the drive shaft 40 and thereafter to locations where lubricant is needed. Other oil pump configurations are also within the scope of this application.

[0044] The invention has been described is in an illustrative manner; many modifications and variations of the present invention are possible. It is therefore to be understood that within the specification, the reference numerals are merely for convenience, and are not to be in any way limiting, and that the invention may be practiced otherwise than is specifically described. Therefore, the invention can be practiced otherwise than is specifically described within the scope of the stated claims following this first disclosed embodiment.

Claims

CLAIMSWhat is claimed is:

1. A scroll compressor assembly, comprising: a housing; a first scroll defining a first involute extending from a first scroll base; a second scroll defining a second involute being received by said second involute and extending from a second scroll base; a shaft being fixedly attached to said first scroll base defining a central shaft axis and being received through a central opening defined by said second scroll base; a bearing hub including an annular wall being pivotally received by said central opening defined by said second scroll base, said bearing hub defining a bearing hub axis and an annular wall axis being offset from said bearing hub axis and said central shaft axis; and said shaft providing pivotal movement to said first scroll and said second scroll relative to said bearing hub and said annular wall providing relative orbital movement to said second involute_relative to said first involute when said first scroll and said second scroll are subject to pivotal movement.

2. The assembly set forth in claim 1, wherein said bearing hub is fixedly attached to an upper frame is stationary relative to said shaft when said shaft provides pivotal movement to said first scroll and said second scroll.

3. The assembly set forth in claim 1, wherein said first scroll and said second scroll are disposed between said upper frame and a central frame, said central frame being stationaryrelative to said shaft when said shaft provides pivotal movement to said first scroll and said second scroll.

4. The assembly set forth in claim 3, wherein said central frame includes a central bearing that receives said shaft for pivotally supporting said shaft with said upper bearing.

5. The assembly set forth in claim 4, wherein said first scroll includes a scroll base with an extension member disposed radially outwardly from said first involute.

6. The assembly set forth in claim 5, wherein said extension member circumscribes said first involute extending to a thrust plate thereby enclosing said first involute and said second involute therebetween.

7. The assembly set forth in claim 5, wherein said second scroll base is aligned to said thrust plate by pins being received by pockets for enabling pivotable movement generated by said shaft to be transferred to said second scroll.

8. The assembly set forth in claim 1, wherein said shaft defines a suction gas path for conveying low pressure gas to a compression chamber via a first scroll aperture.

9. The assembly set forth in claim 8, wherein said first involute and said second involute pressurize the gas received in the compression chamber while moving said pressurized gas radially inwardly toward said shaft.

10. The assembly set forth in claim 9, wherein said compression chamber discharge gas is fluidly connected to a pressure chamber via a fluid passage defined by clearance between said thrust plate and end plate shaft for transferring pressurized gas from said compression chamber to said pressure chamber.11 . The assembly set forth in claim 7, wherein a plurality of pins interconnect said second scroll to said thrust plate said second scroll and said first scroll to rotate about their respective axis while maintaining relative alignment.

12. The assembly set forth in claim 1, wherein said shaft defines an oil bore defined by said shaft and extending in an axial direction of said shaft being parallel to suction gas path.

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