Patent Application
20060233657
The present invention relates to scroll compressors, and more particularly, to discharge valves for preventing reverse rotation of a scroll compressor at shutdown.
Scroll compressors have become widely utilized in many refrigerant compression applications. Scroll compressors are relatively efficient, and are being utilized in more and more applications. In a typical scroll compressor, the compression chambers are defined by two generally spiral wraps. The spiral wraps are formed on individual scroll members, and extend from a base plate. The spiral wraps interfit to define compression chambers. One of the spiral wraps is driven to orbit relative to the other, and the size of the compression chambers changes to compress the entrapped refrigerant.
As the compression chamber nears the end of its cycle, the entrapped gas is exposed to a discharge port. The entrapped gas leaves the discharge port and moves through a check valve to a discharge plenum. The discharge check valve is typically opened during operation of the scroll compressor. The check valve closes the discharge port and desirably prevents backflow once the compressor is stopped.
In scroll compressors, there is a phenomenon known as reverse rotation. This occurs when compressed gas moves back through the discharge port and into the compression chamber to drive the scroll compressor wraps relative to each other in a reverse direction at shutdown of the compressor. This is undesirable, and results in unwanted noise and potential harm to the compressor components.
One method of minimizing the amount of reverse rotation is to minimize the volume of compressed gas which will move between the scroll wraps at shutdown. The present invention provides a discharge valve that is designed to be fast acting in closing the discharge port upon shutdown of the compressor.
A discharge valve, according to the principles of the present invention, includes a valve seat having a seat surface facing downstream of a discharge passage of the scroll compressor. A valve member is provided having a body portion for engaging the seat surface of the valve seat for closing the discharge passage. The valve member includes a guide portion extending axially from the body portion. A retainer is slidably engaged with the guide portion of the valve member and includes at least one passage communicating with a space between the valve member and the retainer. According to one aspect of the present invention, the guide portion of the valve member includes at least one notch portion in communication with the space between the valve member and the retainer. During operation of the scroll compressor, the valve member is lifted away from the valve seat and slidably moves relative to the retainer to an open position. At shutdown, the discharge pressure in the discharge chamber acts upon the valve member through the at least one passage communicating with the space between the valve member and the retainer to cause the valve member to move to its closed position. The notched portions in the guide portion of the valve member serve a dampening effect with regard to the motion of the valve member between the open and closed positions.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
At the outset, it is noted that the herein described compressor embodiments are the subject of commonly assigned U.S. Patent No. 6,139,291 to Perezovchikov, the disclosure of which is incorporated herein by reference. Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in
A drive shaft or crank shaft 30 having an eccentric crank pin 32 at the upper end thereof is rotatably journaled in a first bearing (not shown) in main bearing housing 24 and a second bearing 36 in upper bearing housing 26. Crank shaft 30 has at the lower end a relatively large diameter eccentric bore which communicates with a radially outwardly inclined smaller diameter bore 40 extending upwardly therefrom to the top of crankshaft 30. The lower portion of the shell interior defines an oil sump which is filled with lubricating oil to a level slightly above the lower end of a rotor 46, and the eccentric bore acts as a pump to pump lubricating oil up crankshaft 30 and into bore 40 and ultimately to all the various portions of compressor 10 that require lubrication.
Crankshaft 30 is rotatably driven by an electric motor 48 including a stator 50, windings 52 passing therethrough, and rotor 46 being press fit on crankshaft 30 and having an upper counterweight and a lower counterweight (not shown). An upper surface 58 of upper bearing housing 26 is provided with a flat thrust bearing surface on which is disposed an orbiting scroll member 60 having a spiral vein or wrap 62 extending upward from an end plate 64. Projecting downwardly from a lower surface of end plate 64 of orbiting scroll member 60 is a cylindrical hub 66 having a journal bearing 68 therein, and in which is rotatably disposed a drive bushing 70 having an inner bore 72 in which crank pin 32 is drivingly disposed. Crank pin 32 has a flat on one surface that engages a flat surface (not shown) formed in a portion of bore 72 to provide a radially compliant driving arrangement, such as shown in Assignee's U.S. Pat. No. 4,877,382, the disclosure of which is hereby incorporated herein by reference.
An Oldham coupling 76 is also provided and positioned between orbiting scroll member 60 and upper bearing housing 26 and is keyed to orbiting scroll member 60 and a non-orbiting scroll member 80 to prevent rotational movement of orbiting scroll member 60. Oldham coupling 76 is preferably of the type disclosed in Assignee's U.S. Pat. No. 5,320,506, the disclosure of which is hereby incorporated herein by reference.
Non-orbiting scroll member 80 is provided with a wrap 82 extending downwardly from an end plate 84 is positioned in meshing engagement with wrap 62 of orbiting scroll member 60. Non-orbiting scroll member 80 has a centrally disposed discharge passage 86 that communicates with an upwardly open recess 88 that in turn is in fluid communication with a discharge muffler chamber 90 defined by cap 16 and the partition 22. An annular recess 92 is formed in non-orbiting scroll member 80, within which is disposed a floating seal assembly 94. Recesses 88, 92, and floating seal assembly 94 cooperate to define an axial pressure biasing chamber which receives pressurized fluid being compressed by wraps 62, 82 so as to exert an axial biasing force on the non-orbiting scroll member 80 to thereby urge tips of the respective wraps 62, 82, into sealing engagement with opposed end plate surfaces 98, 100 of end plates 64, 84, respectively. Floating seal assembly 94 is preferably of the type described in greater detail in U.S. Pat. No. 5,156,539, the disclosure of which is incorporated herein by reference. Non-orbiting scroll member 80 is designed to be mounted to main bearing housing 24 in a suitable manner such as disposed in the aforementioned U.S. Pat. Nos. 4,877,382 or 5,102,316, the disclosures of which are incorporated herein by reference.
The present invention is directed towards normally closed mechanical discharge valve assembly 12 that is disposed within recess 88 that is formed in non-orbiting scroll member 80. Discharge valve assembly 12 moves between a fully closed and a fully opened condition during steady state operation of compressor 10. Valve assembly 12 will close during the shutdown of compressor 10. When valve assembly 12 is fully closed, the recompression volume is minimized and reverse flow of discharge gas through scroll members 60, 80 is prohibited. Valve assembly 12 is normally closed as shown in
Referring now to
The valve plate 102 defines a valve seat including a seat surface 108 having a frusto conical shape and facing in a downstream direction from the discharge port 86. The valve plate 102 includes the central aperture 110 adjacent to the seat surface 108. The seat surface 108 is disposed at approximately 50-60 degrees from the axis of the valve plate. An upstream surface 112 of the valve plate 102 is also angularly disposed relative to the axis of the valve plate 102 at approximately 50-60 degrees. The outer perimeter of the valve plate 102 includes a recessed portion 114.
The valve member 104 is generally cup-shaped and includes a generally cylindrical sidewall portion 116 and a base portion 118 enclosing a forward end of the cylindrical sidewall 116. The base portion 118 includes a central nub 120 extending axially therefrom. The outer perimeter of the base portion 118 includes a frusto conical surface 122 between the inner face of the base portion 118 and cylindrical sidewall 116. The frusto conical portion 122 is disposed at approximately 50-60 degrees from the central axis of the valve member. The cylindrical sidewall 116 includes a plurality of equally spaced notches 124 (best seen in
The retainer 106 includes a cylindrical outer sidewall 130 and a retainer base portion 132 disposed on a rearward end of the cylindrical outer sidewall 130. A central stem 134 extends axially from the retainer base portion 132 and includes a through hole 136 extending axially therethrough. The valve member 104 is slidably received on the central stem 134 of the retainer 106. Through operation of the scroll compressor 10, the valve member 104 is opened by gas flow from the scroll compressor. The valve member 104 is freely sliding over the stem 134 of the retainer 106. The venting formations 124, 124′, 124″, 140 provide venting of the space 138 between the valve member 104 and stem 134 which defines a damper cavity on movement of the valve member 104. When the valve member 104 is opening, the gas in the valve cavity 138 is being compressed and leaks away through the restriction hole 136 and stem 134 radial clearance. This causes the pressure in the valve cavity to increase, therefore reducing the valve velocity and impact on the retainer 106. After gas communication through the venting formations 124, 124′, 124″, 140 have been shut off, gas flow to or from the damper cavity is restricted by the valve 104 and stem 134 radial clearance. During a fraction of a revolution, when there is a negative pressure drop across the valve which causes the valve member to go down, pressure in the valve cavity is being reduced due to its increasing volume and pressure drop across the hole 136 and stem 134 radial clearance, reducing the valve velocity and introducing a delay in valve closing.
With reference to
When the valve member 4-20 starts to close, the valve member 4-20 begins to move rapidly under pressure in the volume 4-36 and the spring 4-26. When the notches 4-20c open to allow a flow passage, the pressure in the volume 4-36 drops rapidly and reduces the force pressing down on the valve member 4-20 so that the impact of the valve member 4-20 and valve seat 4-12 is reduced.
With reference to
With reference to
With reference to
The radially extending flange portion 7-28 is received within the cylindrical extending sidewall 7-34 of the valve member so that the valve member is capable of moving axially relative to the retainer 7-22. The valve member 7-18 is optionally provided with radially inwardly extending fingers 7-38 which retain the valve member 7-18 to the retainer 7-22 during installation of the valve assembly 7-10. The retainer 7-22 has an end portion 7-40 which is received in an aperture 7-42 and is crimped radially outwardly in order to retain the retainer 7-22 to the muffler plate 7-24. The muffler plate further includes apertures 7-44, as best illustrated in
With reference to
With reference to
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
