Check valve stop and ports

Details Check valve stop and ports Check valve stop and ports

2000-01-05

2001-05-01

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

Helical working member, e.g., scroll

C418S270000, C137S084000

Reexamination Certificate

active

06224356

ABSTRACT:

BACKGROUND OF THE INVENTION
This application relates to an improvement in discharge valve structure for a scroll compressor wherein return passages to force a valve to a closed position upon reverse rotation of the scroll compressor are optimized.
Scroll compressors are becoming widely utilized in refrigerant compression applications. As is known, a scroll compressor includes a first scroll member having a base and a generally spiral wrap extending from the base. A second scroll member has a base and a generally spiral wrap extending from its base. The two wraps interfit to define compression chambers. The second scroll member orbits relative to the first scroll member. As the orbiting occurs the size of the compression chamber decreases, and gas is compressed and forced towards a central portion of the two wraps. A discharge port extends through the base of the first scroll member at a central location.
Scroll compressors may sometimes experience reverse rotation at shutdown. At shutdown, compressed fluid which has recently been compressed by the scroll members may sometimes move back through the discharge port and into the compression chambers between the two scroll wraps. When this occurs, the orbiting scroll member can be forced to orbit in a reverse direction to that which is normally proper for operation of the scroll compressor. This so-called reverse rotation creates undesirable noise.
Attempts have been made to reduce the occurrence of this reverse rotation at shutdown. One specific attempt involves the use of a discharge check valve which seals the discharge port.
To this end, the check valve is allowed to float within a valve chamber. Gas is communicated to discharge passages radially outward of this valve. The valve sits against the valve seat, and is held upwardly against the valve seat during normal operation. Discharge pressure fluid is communicated to a rear face of the valve; however, during forward operation the flow from the compressed gas holds the valve against the valve seat.
However, when the compressor is stopped, the discharge pressure gas passes through the passages to the rear face of the floating valve. The floating valve is then forced back to close the discharge port.
The known return passages have not been operational as quickly as would be desired. In general, the passages have included straight passages which are parallel to the axis of the orbiting scroll member. Other proposed valves have used the discharge passages to provide the return passage function. This has resulted in some restriction in flow, and thus a delay in the valve moving to the closed position at shutdown.
Other structures have the valve extending outwardly radially beyond the surface of the valve stop. This, however, results in undesirable valve flutter noises during normal operation.
In general, the return passage structure which has been utilized in the prior art has some undesirable characteristics. The present invention improves upon the return passage structure.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, a floating valve selectively abuts a valve stop body in a scroll compressor discharge valve chamber. The floating valve has an outer diameter which is preferably less than or equal to an outer diameter of a valve stop body. The valve stop body is surrounded by discharge passages which extend radially outwardly of the valve stop body. During forward operation of the scroll compressor discharge gas passes through a discharge port and into the discharge passages. The floating valve is held against the valve stop body by discharge gas flow.
Return gas passages are angled non-parallel relative to the orbiting axis of the scroll. In this way, the gas is communicated to a rear face of the valve quickly and without restriction. In one embodiment, the return passages are also non-perpendicular to the axis. For other embodiments, the return passages are perpendicular to the axis.
Further, the angled passages preferably communicate with a central return chamber which communicates to the rear face of the floating valve. The passages are thus able to take advantage of a component of the returning discharge gas flow at shutdown. As the discharge gas begins to move back downwardly into the discharge port, the passages catch that gas and force it against the rear surface of the floating valve such that the floating valve is quickly closed.
Also, during normal operation the discharge gas passes by the return passages and may create a venturi effect holding the valve against the stop.
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.


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patent: 5173042 (1992-12-01), Chambers
patent: 5494422 (1996-02-01), Ukai et al.
patent: 6065948 (2000-05-01), Brown
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patent: 3-267591 (1991-11-01), None
patent: 4-072487 (1992-03-01), None
patent: 4-279782 (1992-10-01), None
patent: 5-149269 (1993-06-01), None
patent: 5-231351 (1993-09-01), None
patent: 6-010868 (1994-01-01), None
patent: 6-173864 (1994-06-01), None

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