Title of Invention	"COMPRESSOR WITH REDUCED DISCHARGE CLEARENCE"
Abstract	A compressor piston has protrusions which extend upwardly into discharge ports to minimize clearance at the end of the compression stroke. The protrusions fit into circumferentially isolated discharge ports, and each of the ports are associated with reed valves. Preferably a cutout portion is formed into the piston head to allow clearance for movement of the suction valve. The suction valve is positioned on an inner face of a valve plate and the discharge reed valves are positioned on an outer face. The protrusions are preferably frustro-conical.

Title of Invention

"COMPRESSOR WITH REDUCED DISCHARGE CLEARENCE"

Abstract

A compressor piston has protrusions which extend upwardly into discharge ports to minimize clearance at the end of the compression stroke. The protrusions fit into circumferentially isolated discharge ports, and each of the ports are associated with reed valves. Preferably a cutout portion is formed into the piston head to allow clearance for movement of the suction valve. The suction valve is positioned on an inner face of a valve plate and the discharge reed valves are positioned on an outer face. The protrusions are preferably frustro-conical.

Full Text	Background of the Invention This invention relates to a compressor piston with reduced discharge clearance wherein projections extend upwardly from an end face of the piston head from plural circumferentially spaced locations, and into a discharge port to reduce clearance volume. Compressor are utilized to compress gases such as refrigerant. One standard type of compressor is a reciprocating compressor wherein a piston head is given between a lower position at which a fluid to be compressed enters the compression cylinder, and an upper or "top" position at which the compressed fluid is driven outwardly of the cylinder. A valve plate is typically placed at the top of the cylinder. The term "top" and "bottom" do not refer to any vertical orientation, but instead only to a position in the cylinder. The valve plate caries both inlet and outlet valves for allowing the flow of fluid into the cylinder, and out of the cylinder at appropriate points in the reciprocating movement of the piston. Various types of the valves are known, an various types of valves plates have been utilized. One type of valve plate has a central concentric discharge valve extending around the center of the cylinder. A suction valve is placed at a location further outwardly. The discharge valve is typically on an outer face of the valve plate, and there is a discharge port volume between the top of the cylinder and the discharge valve through the valve plate. In the prior art it is known to form a concentric ring on the compressor piston to fit upwardly into this volume and to reduce clearance volume. One other type of compressor valving structure uses reed valves. A reed valve would typically cover a plurality of circumferentially spaced ports. In the past, there has been modified in various ways. However, these modifications have for the most part potentially weakened the valve plate, and thus have some drawbacks. Summary of the Invention In the disclosed embodiment of this invention, a piston for a compressor has a plurality of circumferentially spaced protrusions extending above a nominal surface face of the piston. The protrusions fit into circumferentially isolated discharge ports in the valve plate. The discharge ports are associated with reed valves, and the protrusion ensure that the clearance volume is minimized. In a preferred embodiment the piston has at least two protrusion which are non-concentric and preferably each within the same semicircle. Further, the piston has a cutout portion extending into the nominal face of the piston for receiving the suction valve. The suction valve is preferably also a reed valve located to cover circumferentially spaced suction ports. In this manner, die present invention provides a piston for a compressor which minimizes the clearance space in the discharge ports of valve plates utilizing reed valves, which have circumferentially spaced discharge ports. Most preferably die protrusion have frustro-conical outer peripheries to minimize or limit the restriction of gas flow during the final portion of the discharge stroke. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. To meet the aforementioned objectives the invention provides for a compressor with reduced discharge clearance comprising: a cylinder extending along an axis; a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile characterized by; a valve plate closing said cylinder at said top, said valve plate having a plurality of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of circumferentially spaced suction ports within the opposed semi-circle, and reed valves closing said discharge ports, and reed valves being mounted on an outer face of said valve plate; and said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions associated with each of said discharge ports, and said plurality of protrusions being formed to be non-concentric relative to the center of said piston. Brief description of the drawings Figure 1 is a cross-sectional view through a compressor incorporating the present invention. Figure 2 is a top view of the valve plate. Figure 3 is a top view of an inventive piston. Figure 4 is a cross-sectional view through the piston. Detailed description of a preferred embodiment A piston and cylinder combination 20 is illustrated in Figure 1 having a cylinder housing 22 receiving a cylinder liner 24. A piston 26 reciprocates within the cylinder liner 24. A valve plate 28 includes circumferentially spaced discharge ports 30 and 32. A reed valve 34 is placed over the ports 30 and 32. Protrusions 36 extend upwardly from a nominal top surface face 42 of the piston. The outer periphery 38 of the protrusions 36 is frustro-conical. A suction valve 39 is formed on an inner face of the valve plate 28 and aligned with a cutout portion 40 within the piston 26. [14] As shown in Figure 2, the valve plate 28 incorporates suction ports 42 which are circumferentially spaced and both disposed to be in with one semi-circle of the outline of the piston as shown in phantom at 26. As mentioned, the discharge ports 30 and 32 are also in a semi-circle portion. A suction valve 39 covers ports 42. As can be seen, the size of the valve 39 is smaller than cutout 40. [15] As shown in Figure 3, the protrusions 38 extends upwardly from the nominal face 42 and the cutout portion 40 is positioned between the protrusions 38. [16] As shown in Figure 4, the top space of the piston 26 includes a pair of protrusions 36 each having frustro-conical outer periphery 38. The nominal top surface 42 and the cutout portion 40 are also shown. [17] The present invention thus provides a compressor piston which will minimize clearance in compressor discharge ports. The use of the circumferentially spaced plural protrusions provides a modified piston which will minimize clearance in a valve plate utilizing reed valves. Said in another way, the protrusions are non-concentric, and distinct from the prior art. [18] Although a preferred embodiment of this invention has been disclosed, a worker in this art would recognize that certain modifications would come within the scope of this invention. For that reason the following claims should be studied to determine the true scope and content of this invention. We claim: 1. A compressor with reduced discharge clearance comprising: a cylinder extending along an axis; a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile characterized by; a valve plate closing said cylinder at said top, said valve plate having a plurality .of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of circumferentially spaced suction ports within the opposed semicircle, and reed valves closing said discharge ports, and reed valves being mounted on an outer face of said valve plate; and said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions associated with each of said discharge ports, and said plurality of protrusions being formed to be non-concentric relative to the center of said piston. 2. A compressor as claimed in claim 1, wherein a suction valve is positioned on an inner face of said valve plate and covering said suction ports. 3. A compressor as claimed in claim 2, wherein said piston has a suction valve cutout portion extending into said piston and aligned with said suction valve to allow movement of said suction valve within said cutout portion. 4. A compressor as claimed in claim 1, wherein said protrusions have frustroconical outer peripheries to minimize flow resistance between said protrusion and said discharge port. 5. A compressor as claimed in claim 3, wherein said cutout portion has two curved sides and extends across the entire diameter of said piston, with said nominal surfaces being formed on each of said sides, and one of said protrusions being positioned within each of said nominal surface areas. 6. A compressor comprising: a cylinder extending along an axis; a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile: a valve plate closing said cylinder at said top, said valve plate having a plurality of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of suction ports within the opposed semi-cylinder, and reed valves closing said discharge ports and said suction ports, said discharge reed valves being mounted on an outer face of said valve plate and said suction reed valve being mounted on an inner face of said valve plate; and said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions assorted with each of said discharge ports, and said plurality of protrusions being formed within one semi-circle of said piston profile. 7. A compressor as claimed in claim 6, wherein said piston has suction valve cutout portion extending into said piston and aligned with said suction valve to allow movement of said suction valve within said cutout portion. 8. A compressor as claimed in claim 6, wherein said protrusions have frustroconical outer peripheries to minimize flow resistance between said protrusion and said discharge port. 9. A compressor as claimed in claim 8, wherein said cutout portion has two curved sides and extends across the entire diameter of said piston, with said nominal surfaces being formed on each of said sides, and one of said protrusions being positioned within each of said nominal surface areas. 10. A compressor substantially as herein described with reference to the accompanying drawings.

Full Text

Background of the Invention
This invention relates to a compressor piston with reduced discharge clearance wherein projections extend upwardly from an end face of the piston head from plural circumferentially spaced locations, and into a discharge port to reduce clearance volume.
Compressor are utilized to compress gases such as refrigerant. One standard type of compressor is a reciprocating compressor wherein a piston head is given between a lower position at which a fluid to be compressed enters the compression cylinder, and an upper or "top" position at which the compressed fluid is driven outwardly of the cylinder. A valve plate is typically placed at the top of the cylinder. The term "top" and "bottom" do not refer to any vertical orientation, but instead only to a position in the cylinder. The valve plate caries both inlet and outlet valves for allowing the flow of fluid into the cylinder, and out of the cylinder at appropriate points in the reciprocating movement of the piston.
Various types of the valves are known, an various types of valves plates have been utilized. One type of valve plate has a central concentric discharge valve extending around the center of the cylinder. A suction valve is placed at a location further outwardly.
The discharge valve is typically on an outer face of the valve plate, and there is a discharge port volume between the top of the cylinder and the discharge valve through the valve plate. In the prior art it is known to form a concentric ring on the compressor piston to fit upwardly into this volume and to reduce clearance volume.
One other type of compressor valving structure uses reed valves. A reed valve would typically cover a plurality of circumferentially spaced ports. In the past, there has been modified in various ways. However, these modifications have for the most part potentially weakened the valve plate, and thus have some drawbacks.
Summary of the Invention
In the disclosed embodiment of this invention, a piston for a compressor has a plurality of circumferentially spaced protrusions extending above a nominal surface face of the piston. The protrusions fit into circumferentially isolated discharge ports in the valve plate. The discharge ports are associated with reed valves, and the protrusion ensure that the clearance volume is minimized. In a preferred embodiment the piston has at least two protrusion which are non-concentric and preferably each within the same semicircle. Further, the piston has a cutout portion extending into the nominal face of the piston for receiving the suction valve. The suction valve is preferably also a reed valve located to cover circumferentially spaced suction ports.
In this manner, die present invention provides a piston for a compressor which minimizes the clearance space in the discharge ports of valve plates utilizing reed valves, which have circumferentially spaced discharge ports. Most preferably die protrusion have
frustro-conical outer peripheries to minimize or limit the restriction of gas flow during the final portion of the discharge stroke.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
To meet the aforementioned objectives the invention provides for a compressor with reduced discharge clearance comprising:
a cylinder extending along an axis;
a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile characterized by;
a valve plate closing said cylinder at said top, said valve plate having a plurality of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of circumferentially spaced suction ports within the opposed semi-circle, and reed valves closing said discharge ports, and reed valves being mounted on an outer face of said valve plate; and
said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions associated with each of said discharge ports, and said plurality of protrusions being formed to be non-concentric relative to the center of said piston.
Brief description of the drawings
Figure 1 is a cross-sectional view through a compressor incorporating the present
invention.
Figure 2 is a top view of the valve plate.
Figure 3 is a top view of an inventive piston.
Figure 4 is a cross-sectional view through the piston.
Detailed description of a preferred embodiment
A piston and cylinder combination 20 is illustrated in Figure 1 having a cylinder housing 22 receiving a cylinder liner 24. A piston 26 reciprocates within the cylinder liner 24. A valve plate 28 includes circumferentially spaced discharge ports 30 and 32. A reed valve 34 is placed over the ports 30 and 32. Protrusions 36 extend upwardly from a nominal top surface face 42 of the piston. The outer periphery 38 of
the protrusions 36 is frustro-conical. A suction valve 39 is formed on an inner face of the valve plate 28 and aligned with a cutout portion 40 within the piston 26.
[14] As shown in Figure 2, the valve plate 28 incorporates suction ports 42 which
are circumferentially spaced and both disposed to be in with one semi-circle of the outline of the piston as shown in phantom at 26. As mentioned, the discharge ports 30 and 32 are also in a semi-circle portion. A suction valve 39 covers ports 42. As can be seen, the size of the valve 39 is smaller than cutout 40.
[15] As shown in Figure 3, the protrusions 38 extends upwardly from the nominal
face 42 and the cutout portion 40 is positioned between the protrusions 38.
[16] As shown in Figure 4, the top space of the piston 26 includes a pair of
protrusions 36 each having frustro-conical outer periphery 38. The nominal top surface 42 and the cutout portion 40 are also shown.
[17] The present invention thus provides a compressor piston which will minimize
clearance in compressor discharge ports. The use of the circumferentially spaced plural protrusions provides a modified piston which will minimize clearance in a valve plate utilizing reed valves. Said in another way, the protrusions are non-concentric, and distinct from the prior art.
[18] Although a preferred embodiment of this invention has been disclosed, a
worker in this art would recognize that certain modifications would come within the scope of this invention. For that reason the following claims should be studied to determine the true scope and content of this invention.

We claim:
1. A compressor with reduced discharge clearance comprising: a cylinder extending along an axis;
a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile characterized by;
a valve plate closing said cylinder at said top, said valve plate having a plurality .of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of circumferentially spaced suction ports within the opposed semicircle, and reed valves closing said discharge ports, and reed valves being mounted on an outer face of said valve plate; and
said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions associated with each of said discharge ports, and said plurality of protrusions being formed to be non-concentric relative to the center of said piston.
2. A compressor as claimed in claim 1, wherein a suction valve is
positioned on an inner face of said valve plate and covering said
suction ports.
3. A compressor as claimed in claim 2, wherein said piston has a
suction valve cutout portion extending into said piston and aligned
with said suction valve to allow movement of said suction valve
within said cutout portion.
4. A compressor as claimed in claim 1, wherein said protrusions have
frustroconical outer peripheries to minimize flow resistance
between said protrusion and said discharge port.
5. A compressor as claimed in claim 3, wherein said cutout portion has
two curved sides and extends across the entire diameter of said
piston, with said nominal surfaces being formed on each of said
sides, and one of said protrusions being positioned within each of said nominal surface areas.
6. A compressor comprising:
a cylinder extending along an axis;
a piston reciprocating along said axis between a bottom portion and a top portion and having an upper face defining a circular piston profile:
a valve plate closing said cylinder at said top, said valve plate having a plurality of circumferentially spaced discharge ports aligned within one semi-circle of said piston profile and a plurality of suction ports within the opposed semi-cylinder, and reed valves closing said discharge ports and said suction ports, said discharge reed valves being mounted on an outer face of said valve plate and said suction reed valve being mounted on an inner face of said valve plate; and
said piston having a top surface including a plurality of circumferentially spaced protrusions with one of said protrusions assorted with each of said discharge ports, and said plurality of protrusions being formed within one semi-circle of said piston profile.
7. A compressor as claimed in claim 6, wherein said piston has suction
valve cutout portion extending into said piston and aligned with
said suction valve to allow movement of said suction valve within
said cutout portion.
8. A compressor as claimed in claim 6, wherein said protrusions have
frustroconical outer peripheries to minimize flow resistance
between said protrusion and said discharge port.
9. A compressor as claimed in claim 8, wherein said cutout portion has
two curved sides and extends across the entire diameter of said
piston, with said nominal surfaces being formed on each of said
sides, and one of said protrusions being positioned within each of
said nominal surface areas.
10. A compressor substantially as herein described with reference to the accompanying drawings.

Documents:

246-del-2002-abstract.pdf

246-del-2002-claims.pdf

246-del-2002-correspondence-others.pdf

246-del-2002-correspondence-po.pdf

246-del-2002-description (complete).pdf

246-del-2002-drawings.pdf

246-del-2002-form-1.pdf

246-del-2002-form-19.pdf

246-del-2002-form-2.pdf

246-del-2002-form-3.pdf

246-del-2002-form-5.pdf

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Patent Number

220807

Indian Patent Application Number

246/DEL/2002

PG Journal Number

30/2008

Publication Date

25-Jul-2008

Grant Date

05-Jun-2008

Date of Filing

18-Mar-2002

Name of Patentee

CARRIER CORPORATION

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	DUPPERT RONALD
2	KAIDO PETER
3	MACBAIN SCOTT

PCT International Classification Number

F04B 39/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	09/829,075	2001-04-09	U.S.A.