Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1998-03-10
2001-03-20
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S057000
Reexamination Certificate
active
06203300
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a unique slider block for use in a scroll compressor to prevent reverse rotation at shutdown.
Scroll compressors generally include two scroll members each having a base with a generally spiral wrap extending from the base. The two wraps interfit and move into contact to define a plurality of compression chambers. One of the wraps is moved through an orbital movement relative to the other. During the orbital movement, the wraps of the orbiting scroll move along the wraps of the fixed scroll and the compression chambers are compressed towards a discharge point. Scroll compressors are becoming widely utilized as they efficiently compress refrigerant. However, there are many challenges in the design of a scroll compressor.
One challenge is to eliminate noise that occurs at shutdown of the scroll compressor. At shut down there will typically be a quantity of compressed fluid between the orbiting and fixed scroll wraps. Since the motor is no longer driving the orbiting scroll, the compressed fluid may sometimes to drive the orbiting scroll in a reverse rotational direction relative to the fixed scroll member. This reverse rotation is undesirable and causes noise at shutdown. This noise may be interpreted by a consumer as a design or unit flaw. Thus, it is desirable to eliminate reverse rotation at shutdown.
SUMMARY OF THE INVENTION
In the disclosed embodiment of the present invention, a slider block is placed between an eccentric and the orbiting scroll member. The slider block is effective to change the offset in the rotational axis between the eccentric and the orbiting scroll. This allows change in the orbit radius which in turn allows the orbiting scroll to move into and maintain engagement with the fixed scroll.
During rotation in a forward direction, forces cause the slider block to move in a first direction which allows the orbiting scroll to move into engagement with the fixed scroll. Once the orbiting scroll is in sealing engagement with the fixed scroll, the compression chambers are defined and compression occurs with further forward movement.
At shutdown, as the orbiting scroll slows and begins to move in a reverse direction due to the storage of compressed fluid, the slider block moves in a second direction. Interfitting structure between the eccentric and the slider block contact to provide a stop. This interfitting structure blocks further relative movement of the eccentric and slider block. The slider block then prevents any further movement of orbiting scroll axis relative to fixed scroll axis, and such that the scroll wraps are held out of contact with each other. There are thus gaps between the wraps of the orbiting and fixed scrolls and the discharge pressure is dissipated at shutdown.
In the preferred embodiment of this invention, the slider block and eccentric are designed such that the predominant force moving the slider block in the first direction to its forward position is centrifugal force. The centrifugal force is relatively great when compared to the frictional forces encountered by the slider block between both the orbiting scroll and eccentric, and overcomes these frictional forces during normal operation. As the scroll slows from full forward speed to zero, and then the entrapped gas driven reverses at low speed, centrifugal force drops. During entrapped gas caused reverse rotation, the rotational speed of the orbiting scroll is much less than encountered during powered rotation. Thus, the centrifugal force component is much smaller. The frictional forces may overcome the centrifugal force, and move the slider block to the stop position, as described above.
In a preferred embodiment of this invention, the interfitting stop structure incorporates a relatively flat surface formed in an inner bore in the slider block. The eccentric is formed with a mating surface which selectively contacts the flat surface on the slider block to define the stop position. The eccentric is preferably formed with an arc surface which selectively contacts the slider block stop surface. Thus, there is line contact between the eccentric and the slider block at the stop position.
In a preferred embodiment, the stop structure on the slider block and the eccentric is formed over a small portion of the axial length of the members. Beyond this small portion, the members have generally cylindrical shapes, and function as in the prior art.
With the present invention, when the scroll compressor is driven in a forward direction, the slider block is driven by centrifugal force such that its stop portion is maintained out of engagement with the mating stop portion on the eccentric. The orbiting scroll wrap is allowed to move into contact with the fixed scroll wrap and compression can occur. However, at shutdown, should the compressed gas begin to drive the orbiting scroll in a reverse direction relative to the fixed scroll, the slider block will roll to the stop position due to the relatively great frictional forces. The stop surface on the eccentric now abuts the stop surface on the slider block. The orbiting scroll is pulled away from the fixed scroll, creating a gap between the respective wraps. The previously compressed gas is thus dissipated and reverse rotation does not occur.
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.
REFERENCES:
patent: 5165879 (1992-11-01), Kondo et al.
patent: 5174738 (1992-12-01), Baumann
patent: 5199862 (1993-04-01), Kondo et al.
patent: 5201645 (1993-04-01), Steele
patent: 5433589 (1995-07-01), Wada et al.
patent: 5452995 (1995-09-01), Izumi et al.
patent: 5496157 (1996-03-01), Shoulders
patent: 5496158 (1996-03-01), Barito et al.
patent: 5582513 (1996-12-01), Shigeoka et al.
patent: 5-248371 (1993-09-01), None
PCT Search Report.
Hill Joe T.
Hunnicutt John M.
Williams John R.
Denion Thomas
Trieu Thai-Ba
LandOfFree
Scroll compressor with structure for preventing reverse... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Scroll compressor with structure for preventing reverse..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Scroll compressor with structure for preventing reverse... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2496680