Patent Application
20130251577
The present invention generally relates to scroll compressors for compressing refrigerant, and more particularly to an apparatus to reduce edge loading of the drive bearing in a scroll compressor.
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. U.S. Pat. No. 6,398,530 to Hasemann; U.S. Pat. No. 6,814,551, to Kammhoff et al.; 6,960,070 to Kammhoff et al.; and U.S. Pat. No. 7,112,046 to Kammhoff 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 entire disclosures of U.S. Pat. Nos. 6,398,530; 7,112,046; 6,814,551; and 6,960,070 are hereby incorporated by reference in their entireties.
As is exemplified by these patents, scroll compressors assemblies 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 movable 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 movable scroll compressor member is driven about an orbital path about a central axis for the purposes of compressing refrigerant. An appropriate drive unit, typically an electric motor, is provided usually within the same housing to drive the movable scroll member.
Embodiments of the invention described hereinbelow represent an advancement over the state of the art with respect to 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.
Typically, scroll compressors using “slider block radial compliance” rely on an eccentric bearing (the slider block) which is separate from the eccentric drive shaft. The bearing fits over an eccentric pin on the end of the shaft and is engaged through a drive surface which allows the bearing to move radially while being driven rotationally by the shaft. In some instances, due to the cantilevered nature of the drive bearing, shaft deflections under load can result in misalignment of the drive bearing causing edge loading. The deflection of the shaft is transferred to the slider block through the drive surface.
In one aspect, embodiments of the invention provide a scroll compressor that includes a housing and scroll compressor bodies disposed in the housing. The scroll bodies include a first scroll body and a second scroll body. The first and second scroll bodies have respective bases and respective scroll ribs that project from the respective bases. Further, the scroll ribs mutually engage, wherein the second scroll body is movable relative to the first scroll body to compress fluid. A drive unit is configured to rotate a drive shaft to drive the second scroll body in an orbital path. The drive shaft has an eccentric drive pin configured to engage a drive hub on the second scroll body. The scroll compressor further includes a slider block that fits over the drive pin and provides radial compliance of the first scroll body. The slider block has a first drive surface configured to engage a second drive surface of the drive pin. In particular embodiments of the invention, the second drive surface is shorter than the overall length of the drive pin, such that the slider block can tilt about one or more edges of the second drive surface when the drive shaft is deflected under load.
In alternate embodiments of the invention, the first drive surface of the slider block, rather than the second drive surface, is a raised surface that is shorter than the overall length of the drive pin. In this embodiment, the slider block is able to tilt about one or more edges of the first drive surface when the drive shaft is deflected under load to provide improved radial compliance for the movable scroll body.
In a particular embodiment, the second drive surface is raised with respect to an exterior surface portion of the drive pin. In a more particular embodiment, the second drive surface is generally rectangular with a substantially flat outer surface. In an even more particular embodiment, the length of the second drive surface is 25% to 50% of the overall drive pin length. In an alternate embodiment in which the first drive surface is the raised, surface, the length of the first drive surface is 25% to 75% of the overall drive pin length.
In a further embodiment, the slider block includes a cylindrical exterior surface and an opening defined by an interior surface, the interior being having two rounded portions and two flat portions. In a certain embodiment, the two flat portions comprise a first flat portion and a second flat portion, the first flat portion being longer than the second flat portion. In a more particular embodiment, the first flat portion abuts a flat portion of the drive pin. In an even more particular embodiment, the second flat portion functions to keep the slider block in the correct position with respect to the drive pin.
In another aspect, embodiments of the invention provide a method of providing radial compliance for the first scroll body in a scroll compressor. The method includes configuring a slider block to assemble onto a drive pin eccentrically located at one end of a drive shaft. The drive pin has an exterior raised drive surface to engage a drive surface of the slider block. In a particular embodiment, the raised drive surface has a shorter length than the overall length of the drive pin, such that the slider block can tilt back and forth on respective edges of the raised drive surface where these edges engage the slider block. The method also includes assembling the slider block onto the drive pin, and assembling a movable scroll member onto the slider block. In certain embodiments, the movable scroll member has a cylindrical hub configured to receiver the slider block.
In a particular embodiment of the method, assembling the slider block to the drive pin comprises assembling a first flat portion of an interior surface of the slider block to a corresponding flat portion of the drive pin. In a more particular embodiment, assembling the slider block to the drive pin further comprises assembling a slider block having a second flat portion configured to keep the slider block in the correct position with respect to the drive pin.
In a particular embodiment, the method further includes assembling a sleeve between the slider block and the cylindrical hub of the movable scroll member. In a further embodiment, the slider block includes a chamfered surface that extends axially from one end of the slider block, the chamfered surface having one or more notched openings to prevent the trapping of gas beneath the slider block.
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 figures as a scroll compressor assembly 10 generally including an outer housing 12 in which a scroll compressor 14 can be driven by a drive unit 16. The scroll compressor assembly 10 may be arranged in a refrigerant circuit for refrigeration, industrial cooling, freezing, air conditioning or other appropriate applications where compressed fluid is desired. Appropriate connection ports provide for connection to a refrigeration circuit and include a refrigerant inlet port 18 and a refrigerant outlet port 20 extending through the outer housing 12. The scroll compressor assembly 10 is operable through operation of the drive unit 16 to operate the scroll compressor 14 and thereby compress an appropriate refrigerant or other fluid that enters the refrigerant inlet port 18 and exits the refrigerant outlet port 20 in a compressed high-pressure state.
The outer housing 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
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. As can also be seen from
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 a stator 50 comprising electrical coils and a rotor 52 that is coupled to the drive shaft 46 for rotation together. The stator 50 is supported by the outer housing 12, either directly or via a spacer, or adapter. The stator 50 may be press-fit directly into outer housing 12, or may be fitted with an adapter (not shown) and press-fit into the outer housing 12. In a particular embodiment, the rotor 52 is mounted on the drive shaft 46, which is supported by upper and lower bearings 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 parallel to the central axis 54, while the terms “radial’ or “radially-extending” indicates a feature that projects or extends in a direction perpendicular to the central axis 54.
With reference to
In the embodiment of
The drive shaft 46 further includes an offset eccentric drive section 74 that has a cylindrical drive surface 75 (shown in
As shown in
In certain embodiments such as the one shown in
The upper bearing member or crankcase 42 also provides axial thrust support to the movable scroll compressor body 112 through a bearing support via an axial thrust surface 96 of the thrust bearing 84. While, as shown
Turning in greater detail to the scroll compressor 14, the scroll compressor includes first and second scroll compressor bodies which preferably include a stationary fixed scroll compressor body 110 and a movable scroll compressor body 112. 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 movable scroll compressor body 112 is arranged for orbital movement relative to the fixed scroll compressor body 110 for the purpose of compressing refrigerant. The fixed scroll compressor body includes a first rib 114 projecting axially from a plate-like base 116 and is designed in the form of a spiral. Similarly, the movable scroll compressor body 112 includes a second scroll rib 118 projecting axially from a plate-like base 120 and is in the shape 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 other respective scroll 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 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 (see e.g.
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 the 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 bushing drive hub 128 in order to move the movable scroll compressor body 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 typically includes a counterweight 130 that is mounted at a fixed angular orientation to the drive shaft 46. The counterweight 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. The counterweight 130 includes an attachment collar 132 and an offset weight region 134 (see counterweight 130 shown best in
With reference to
In a particular embodiment of the invention, a central region of the floating seal 170 includes a plurality of openings 175. In the embodiment shown, one of the plurality of openings 175 is centered on the central axis 54. That central opening 177 is adapted to receive a rod 181 which is affixed to the floating seal 170. As shown in
In certain embodiments, when the floating seal 170 is installed in the space between the inner hub region 172 and the peripheral rim 174, the space beneath the floating seal 170 is pressurized by a vent hole (not shown) drilled through the fixed scroll compressor body 110 to chamber 122 (shown in
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.
During operation, the scroll compressor assembly 10 is operable to receive low-pressure refrigerant at the housing inlet port 18 and compress the refrigerant for delivery to the high-pressure chamber 180 where it can be output through the housing outlet port 20. This allows the low-pressure refrigerant to flow across the electrical motor assembly 40 and thereby cool and carry away from the electrical motor assembly 40 heat which can be generated by operation of the motor. Low-pressure refrigerant can then pass longitudinally through the electrical motor assembly 40, around and through void spaces therein toward the scroll compressor 14. The low-pressure refrigerant fills the chamber 31 formed between the electrical motor assembly 40 and the outer housing 12. From the chamber 31, the low-pressure refrigerant can pass through the upper bearing member or crankcase 42 through the plurality of spaces 244 that are defined by recesses around the circumference of the crankcase 42 in order to create gaps between the crankcase 42 and the outer housing 12. The plurality of spaces 244 may be angularly spaced relative to the circumference of the crankcase 42.
After passing through the plurality of spaces 244 in the crankcase 42, the low-pressure refrigerant then enters the intake area 124 between the fixed and movable scroll compressor bodies 110, 112. From the intake area 124, the low-pressure refrigerant enters between the scroll ribs 114, 118 on opposite sides (one intake on each side of the fixed scroll compressor body 110) and is progressively compressed through chambers 122 until the refrigerant reaches its maximum compressed state at the compression outlet 126 from which it subsequently passes through the floating seal 170 via the plurality of openings 175 and into the high-pressure chamber 180. From this high-pressure chamber 180, high-pressure compressed refrigerant then flows from the scroll compressor assembly 10 through the housing outlet port 20.
As is evident from the exploded view of
Further, the chamfered end portion 162 includes at least one notched opening 163. In the embodiment shown, the slider block 150 has two notched openings 163, but, in alternate embodiments, may have fewer or greater than two such openings. The notched openings 163 act as vents that allow refrigerant gas that is trapped in the compressor oil to escape. Trapped refrigerant gas can dilute the oil degrading the quality of the oil that is lubricating the bearing surfaces. It is also possible that, during operation of the scroll compressor assembly 10, a volume of the trapped refrigerant gas can become pressurized, and, in this case, move the slider block 150 upward within the movable scroll body cylindrical bushing drive hub 128.
In the embodiment of
As can be seen from the end view in
One of ordinary skill in the art will recognize that, in alternate embodiments of the invention, the shorter raised plateau-like drive surface could be located on a drive surface on the inner periphery of the slider block 150 to perform the same function, i.e., to provide radial compliance for the movable scroll body 122. For the sake of expediency, additional drawings showing this raised plateau-like surface on the slider block 150 have not been added. However, one skilled in the art will recognize that the drawings provided herewith are sufficient to demonstrate that the concept of a raised drive surface to provide improved radial compliance can be applied to the slider block 150 as well as the drive pin 74.
We now refer to
In the operation of a conventional scroll compressor, if the drive pin is deflected or bowed under load so that the drive surface is at an angle to a longitudinal axis of the scroll compressor assembly, the drive bearing or slider block is also tilted and the load is transferred to a lower edge of the drive pin (i.e., to the right in the side view of
However, embodiments of the present invention address this problem by limiting the drive surface 158 to a shorter length. As shown in
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.
