Patent Application
20170022989
This invention generally relates to scroll compressors for compressing refrigerant.
A scroll compressor is a certain type of compressor that is used to compress refrigerant for such applications as refrigeration, air conditioning, industrial cooling and freezer applications, and/or other applications where compressed fluid may be used. Such prior scroll compressors are known, for example, as exemplified in U.S. Pat. No. 6,398,530 to Hasemann; U.S. Pat. No. 6,814,551, to Kammhoff et al.; U.S. Pat. No. 6,960,070 to Kammhoff et al.; U.S. Pat. No. 7,112,046 to Kammhoff et al.; and U.S. Pat. No. 7,997,877, to Beagle et al., all of which are assigned to a Bitzer entity closely related to the present assignee. As the present disclosure pertains to improvements that can be implemented in these or other scroll compressor designs, the disclosures of U.S. Pat. Nos. 6,398,530, 7,112,046, 6,814,551, 7,997,877 and 6,960,070 are hereby incorporated by reference in their entireties.
Additionally, particular embodiments of scroll compressors are disclosed in U.S. Pat. No. 6,582,211 to Wallis et al., U.S. Pat. No. 6,428,292 to Wallis et al., and U.S. Pat. No. 6,171,084 to Wallis et al., the teachings and disclosures of which are hereby incorporated by reference in their entireties.
As is exemplified by these patents, scroll compressors conventionally include an outer housing having a scroll compressor contained therein. A scroll compressor includes first and second scroll compressor members. A first compressor member is typically arranged stationary and fixed in the outer housing. A second scroll compressor member is moveable relative to the first scroll compressor member in order to compress refrigerant between respective scroll ribs which rise above the respective bases and engage in one another. Conventionally the moveable scroll compressor member is driven about an orbital path about a central axis for the purpose of compressing refrigerant. An appropriate drive unit, typically an electric motor, is usually provided within the same housing to drive the movable scroll member.
Embodiments of the present invention represent an advancement of the state of the art for scroll compressors. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
In one aspect, embodiments of the invention provide a scroll compressor with unfastened thrust plate includes a compressor housing and scroll compressor bodies disposed in the compressor housing. The scroll bodies include a fixed scroll body and a moveable scroll body. The fixed and moveable scroll bodies have respective bases and respective scroll ribs that project from the respective bases. The scroll ribs mutually engage. The moveable scroll body is movable relative to the fixed scroll body for compressing fluid. An upper bearing member provides axial thrust support to the moveable scroll compressor body through a bearing support via an unfastened thrust plate that is located between the upper bearing member and the moveable scroll body. The unfastened thrust plate has no means of attachment to the upper bearing member or to the moveable scroll body.
In a particular embodiment, the unfastened thrust plate is rotationally unconstrained. In some embodiments, the unfastened thrust plate is constrained radially by an upper bearing member. The unfastened thrust plate may be concentrically located within a cylindrical portion of the upper bearing member. Furthermore, the unfastened thrust plate may be constrained axially by the upper bearing member and the moveable scroll body. In certain embodiments, the unfastened thrust plate has a central opening to accommodate a drive shaft of the compressor. Also, the unfastened thrust plate may include a central hub that defines the central opening. In a further embodiment, the unfastened thrust plate has a plate-like perimeter region, and wherein the central hub is raised above the plate-like region.
In a certain embodiment of the invention, the unfastened thrust plate nests within a cylindrical recess in a top of the upper bearing member. In this embodiment, a radial clearance between the unfastened thrust plate and the upper bearing member ranges from RC 3 to RC 8 based on the ANSI B4.1 tolerance fit limits, but more preferably ranges from RC 3 to RC 5. In this case, the radial clearance may be defined as the average distance between an outer diameter of the unfastened thrust plate and an inner diameter of the upper bearing member.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
An embodiment of the present invention is illustrated in
The outer housing 12 for the scroll compressor assembly 10 may take many forms. In particular embodiments of the invention, the outer housing 12 includes multiple shell sections. In the embodiment of
As can be seen in the embodiment of
During assembly, these components may be assembled such that when the top end housing section 26 is joined to the central cylindrical housing section 24, a single weld around the circumference of the outer housing 12 joins the top end housing section 26, the separator plate 30, and the central cylindrical housing section 24. In particular embodiments, the central cylindrical housing section 24 is welded to the bottom shell 28, though, as stated above, alternate embodiments would include other methods of joining (e.g., fasteners) these sections of the outer housing 12.
While the separator plate 30 could be a stamped steel component, it could also be constructed as a cast and/or machined member (and may be made from steel or aluminum) to provide the ability and structural features necessary to operate in proximity to the high-pressure refrigerant gases output by the scroll compressor 14. By casting or machining the separator plate 30 in this manner, heavy stamping of such components can be avoided.
Assembly of the outer housing 12 results in the formation of an enclosed chamber 31 that surrounds the drive unit 16, and partially surrounds the scroll compressor 14. In particular embodiments, the top end housing section 26 is generally dome-shaped and includes a respective cylindrical side wall region 32 that abuts the top of the central cylindrical housing section 24, and provides for closing off the top end of the outer housing 12.
In a particular embodiment, the drive unit 16 in is the form of an electrical motor assembly 40. The electrical motor assembly 40 operably rotates and drives a shaft 46. Further, the electrical motor assembly 40 generally includes an outer annular motor housing 48, a stator 50 comprising electrical coils and a rotor 52 that is coupled to the drive shaft 46 for rotation together. In a particular embodiment, the rotor 52 is mounted on the drive shaft 46, which is supported by upper and lower bearing members 42, 44. Energizing the stator 50 is operative to rotatably drive the rotor 52 and thereby rotate the drive shaft 46 about a central axis 54.
Applicant notes that when the terms “axial” and “radial” are used herein to describe features of components or assemblies, they are defined with respect to the central axis 54. Specifically, the term “axial” or “axially-extending” refers to a feature that projects or extends in a direction generally parallel to the central axis 54, while the terms “radial” or “radially-extending” indicates a feature that projects or extends in a direction generally perpendicular to the central axis 54. Some minor variation from parallel and perpendicular is permissible.
With reference to
Referring to
The drive shaft 46 further includes an offset eccentric drive section 74 that has a cylindrical drive surface 75 about an offset axis that is offset relative to the central axis 54. This offset drive section 74 is journaled within a cavity of the movable scroll member 112 of the scroll compressor 14 to drive the movable scroll member 112 of the scroll compressor 14 about an orbital path when the drive shaft 46 is rotated about the central axis 54. To provide for lubrication of all of these bearing surfaces, the outer housing 12 provides an oil lubricant sump 76 at the bottom end in which suitable oil lubricant is provided. The drive shaft 46 has an impeller tube 47 that acts as an oil pump when the drive shaft 46 is spun and thereby pumps oil out of the lubricant sump 76 into an internal lubricant passageway 80 within the drive shaft 46. During rotation of the drive shaft 46, centrifugal force acts to drive lubricant oil up through the lubricant passageway 80 against the action of gravity. In are particular embodiment, the lubricant passageway 80 include various radial passages to feed oil through centrifugal force to appropriate bearing surfaces and thereby lubricate sliding surfaces as may be desired.
As shown in
In conventional scroll compressors, the location of the thrust plate is typically fixed axially, radially, and rotationally by a plurality of fasteners, such as threaded bolts. In the unfastened thrust plate 84 of the current invention, as shown in
Positional error after machining can cause deformation of the thrust plate surface 96 if the bolts fasten these parts together. Deformation of the thrust plate surface 96 against a flat movable scroll compressor member thrust plate surface 96 can cause “hot spots” where increased pressure at the high spots on the warped thrust plate 84 meets the movable scroll compressor member 112.
Embodiments of the present invention also serve to reduce manufacturing costs by eliminating the machining necessary to create the bolt holes in the thrust plate 84, and the threaded holes in the crankcase 42. Further, multiple fasteners are eliminated, thus removing their cost from the compressor assembly cost, and removing the labor cost of assembling these fasteners, reducing the compressor assembly time, and reducing the potential for deformation of the thrust plate surface due to bolt tightening.
In the event that unbalanced sliding friction causes the unfastened thrust plate 84 to rotate in position, the plate 84 will wear in evenly, “seeking” an ideal worn surface complementary of the mating surface on the movable scroll compressor member 112. Lastly, if either part has a minor surface flatness error, the floating, or unfastened, configuration of the thrust plate 84 will allow the for thrust plate 84 to “seek” a low resistance orientation and operate in that orientation, thus reducing the power needed to movable scroll compressor member 112, thus increasing overall compressor efficiency.
As the movable scroll compressor member 112 orbits, frictional forces transmitted through its thrust plate surface 96 to the thrust plate 84 act to carry the thrust plate 84 along that orbit with it. The thrust plate 84 contacts a crankcase pilot inner diameter 104 which restrains the thrust plate 84 rotationally such that locally, the thrust plate 84 outer diameter 106 does not slide relative to the crankcase 42 pilot inner diameter 104. Locally, the thrust plate 84 rolls on its outer diameter 106, along the surface of the pilot diameter 104 of the crankcase 42. In a particular embodiment, the crankcase 42 pilot inner diameter 104 is defined by a cylindrical recess in a top portion of the crankcase 42, such that the thrust plate 84 nests within the cylindrical recess. The cylindrical recess is bounded by a top surface 109 of the crankcase 42 and by the crankcase pilot inner diameter 104. Further, by allowing the thrust plate 84 to move, the total relative sliding motion is reduced between the movable scroll compressor member 112 and the thrust plate 84, and some motion is transferred to a bottom face 108 of the thrust plate 84. This extends the life of the thrust plate 84 and movable scroll compressor member 112 by reducing wear on their respective surfaces.
To reduce any noise associated with the unfastened thrust plate 84 during compressor operation, a relatively small radial clearance between the thrust plate outer diameter 106 and the crankcase pilot inner diameter 104. Maintaining such a small radial clearance reduces the hertzian stress, reduces the possibility of thrust plate 84/crankcase 42 impact, and thus reduces the possibility of noise. The radial gap must be optimized for reduction is noise, reduction in hertzian stress, balance of relative motion between the an interface of the movable scroll compressor member 112 and the thrust plate surface 96, and the interface of the thrust plate bottom surface 108 and the mating top surface 109 of the crankcase 42, while maintaining sufficient surface overlap between the thrust plate 84 and it's mating members to maintain an oil film all around.
In a particular embodiment, the hertzian stresses and accompanying noise are reduced by maintaining the radial clearance between the thrust plate outer diameter 106 and crankcase pilot inner diameter 104 within a range of RC 3 through RC 8 based on standard ANSI B4.1 engineering and manufacturing tolerance fit limits. Running and sliding fits (RC) are intended to provide a similar running performance, with lubrication allowance, throughout a range of sizes. Thus, RC fits are scalable measures in which the allowable clearances change with the size of the parts being considered. But, as stated above, the range of clearances associated with a particular RC fit number is intended to provide similar running performance RC 3 indicates precision running fits, which are the closest fits that can be expected to run freely, and are intended for precision work at slow speeds and light journal pressures, but are not suitable where appreciable temperature differences are likely to be encountered. At the other end of the range, RC 8 indicates loose running fits intended for use where wide commercial tolerances may be necessary, together with an allowance, on the external member.
As stated above, the allowable range of fits for radial clearance between the thrust plate 84 and crankcase 42 is RC 3 to RC 8, but preferably from RC 5 to RC 8. This relatively looser range of running clearances allows for the high speeds and high temperatures likely to occur at the interfaces between the movable scroll member 112 and thrust plate 84, as well as between the thrust plate 84 and the crankcase 42 under normal operating conditions.
Turning in greater detail to the scroll compressor 14, the scroll compressor body is provided by first and second scroll compressor bodies which preferably include a relatively stationary fixed scroll compressor member 110 and a second scroll compressor member 112 movable relative to the fixed scroll compressor member 110. While the term “fixed” generally means stationary or immovable in the context of this application, more specifically “fixed” refers to the non-orbiting, non-driven scroll member, as it is acknowledged that some limited range of axial, radial, and rotational movement is possible due to thermal expansion and/or design tolerances.
The second scroll compressor member 112 is arranged for orbital movement relative to the fixed scroll compressor member 110 for the purpose of compressing refrigerant. The fixed scroll compressor member 110 includes a first rib 114 projecting axially from a plate-like base 116 and is designed in the form of a spiral. Similarly, the second movable scroll compressor body 112 includes a second scroll rib 118 projecting axially from a plate-like base 120 and is in the design form of a similar spiral.
The scroll ribs 114, 118 engage in one another and abut sealingly on the respective base surfaces 120, 116 of the respectively other compressor body 112, 110. As a result, multiple compression chambers 122 are formed between the scroll ribs 114, 118 and the bases 120, 116 of the respective compressor bodies 112, 110. Within the chambers 122, progressive compression of refrigerant takes place. Refrigerant flows with an initial low pressure via an intake area 124 surrounding the scroll ribs 114, 118 in the outer radial region. Following the progressive compression in the chambers 122 (as the chambers progressively are defined radially inward), the refrigerant exits via a discharge port 126 which is defined centrally within the base 116 of the fixed scroll compressor member 110. Refrigerant that has been compressed to a high pressure can exit the chambers 122 via the discharge port 126 during operation of the scroll compressor.
The movable scroll compressor body 112 engages the eccentric offset drive section 74 of the drive shaft 46. More specifically, the receiving portion of the movable scroll compressor body 112 includes a cylindrical bushing drive hub 128 which slideably receives the eccentric offset drive section 74 with a slideable bearing surface provided therein. In detail, the eccentric offset drive section 74 engages the cylindrical drive hub 128 in order to move the second scroll compressor member 112 about an orbital path about the central axis 54 during rotation of the drive shaft 46 about the central axis 54. Considering that this offset relationship causes a weight imbalance relative to the central axis 54, the assembly preferably includes a counter weight 130 that is mounted at a fixed angular orientation to the drive shaft 46.
The counter weight 130 acts to offset the weight imbalance caused by the eccentric offset drive section 74 and the movable scroll compressor body 112 that is driven about an orbital path (e.g. among other things, the scroll rib is not equally balanced). The counter weight 130 includes an attachment collar 132 and an offset weight region 134 (see counter weight 130 shown in
With reference to
Additionally, the key coupling includes four second keys 152 in which opposed pairs of the second keys 152 are linearly aligned substantially parallel relative to a second traverse lateral axis 154 that is perpendicular to the first lateral axis 146. There are two sets of the second keys 152 that act cooperatively to receive projecting sliding guide portions 156 that project from the base 120 on opposite sides of the movable scroll compressor body 112. The guide portions 156 linearly engage and are guided for linear movement along the second traverse lateral axis 154 by virtue of sliding linear guiding movement of the guide portions 156 along sets of the second keys 152.
By virtue of the key coupling 140, the second scroll compressor member 112 has movement restrained relative to the fixed scroll compressor member 110 along the first lateral axis 146 and second traverse lateral axis 154. This results in the prevention of any relative rotation of the moveable scroll body as it allows only translational motion. More particularly, the fixed scroll compressor member 110 limits motion of the key coupling 140 to linear movement along the first lateral axis 146; and in turn, the key coupling 140 when moving along the first lateral axis 146 carries the moveable scroll 112 along the first lateral axis 146 therewith. Additionally, the movable scroll compressor body 112 can independently move relative to the key coupling 140 along the second traverse lateral axis 154 by virtue of relative sliding movement afforded by the guide portions 156 which are received and slide between the second keys 152. By allowing for simultaneous movement in two mutually perpendicular axes 146, 154, the eccentric motion that is afforded by the eccentric offset drive section 74 of the drive shaft 46 upon the cylindrical drive hub 128 of the movable scroll compressor body 112 is translated into an orbital path movement of the movable scroll compressor body 112 relative to the fixed scroll compressor member 110.
Referring in greater detail to the fixed scroll compressor member 110, this body 110 is fixed to the upper bearing member 42, capturing the second scroll compressor member 112 between the fixed scroll member 110 and the upper bearing member 42. In a particular embodiment, the fixed scroll compressor body 110, together with the separator plate 30, separates a high pressure chamber 180 from the relatively lower pressure region of the compressor 14 contained within the outer housing 12. The central hub 178 of the fixed scroll compressor 110 body includes a circumferential O-ring groove 177, and when assembled with an O-ring 179, seals against the central cylindrical bore of the separator plate 30, preventing the return of high pressure compressed refrigerant to the relatively lower pressure region of the compressor assembly 14. At the interface between the separator plate 30 and the top end housing section 26, a fillet weld joins the end face of the outer cylindrical wall section of the separator plate 30 with the inside surface of the top end housing section 26, thus preventing the return of high pressure compressed refrigerant to the relatively lower pressure region of the compressor assembly 14.
The fillet weld allows for the separator plate 30 to be assembled to the top end housing section 26 prior to final assembly and weld of the compressor housing 12. This allows for inspection and confirmation of positional alignment between the central axis 54 of the top end housing section 26 and the central cylindrical bore of the separator plate 30.
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context
