Scroll type compressor

Details Scroll type compressor Scroll type compressor

1999-06-09

2001-02-27

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

Helical working member, e.g., scroll

Reexamination Certificate

active

06193488

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Applications No. H.10-165342 filed on Jun. 12, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll type compressor for sucking, compressing and discharging fluid, more particularly, the construction of the spiral elements thereof.
2. Description of Related Art
A scroll type compressor, as known well, compresses fluid in a manner that the volume of the operation chamber, which is constituted by bringing a movable scroll spiral element into contact with a fixed scroll spiral element, is reduced according to the rotation of the movable scroll spiral element. However, due to a fabrication error on manufacturing the respective spiral elements or a deformation of the spiral elements by compression reaction and thermal expansion, there may cause a problem that both spiral elements come to an insufficient contact with each other and fluid leaks to a lower pressure side between the adjacent operation chambers.
To cope with this problem, it has been proposed, as described in JP-A-57-62988 and Jp-A-58-13184, that the dimensions of the respective spiral elements are designed to ensure the accurate contact of both the spiral elements within an angle of 360 degrees from the spiral starting point and the spiral elements are provided with relief after the angle of 360 degrees to prevent the possible contact of the spiral elements.
However, when both the spiral elements come to the positive contact within the range of the center portions of the spiral elements, lubricant oil tends to be compressed at the operation chamber at the center portions where the volume is reduced and so called “liquid compression” may occur. Further, there is a fear that the spiral elements may be broken down by an excessive pressure increase of the operation chamber, because the compression reaction becomes larger as the operation chamber is located more nearly to the center portion.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above mentioned problem, and an object of the present invention is to provide a scroll type compressor in which the spiral elements are constructed not to be easily broken down without affecting the compression efficiency (capacity). To achieve the object, at least one of the spiral elements is provided with relief at the center and outer periphery portions to prevent the mutual contact of the spiral elements during the ranges thereof and the spiral elements come to contact with each other only at the intermediate portion of the spiral elements. Even if the relief is formed at the center and outer periphery portions of the spiral elements, the compression efficiency can not be largely lowered, but, if anything, the efficiency may be slightly increased. On the other hand, the possible brake down of the spiral elements can be effectively prevented, as the center portion of the spiral elements is provided with the relief and the pressure at the center portion of the operation chamber can not be excessively compressed. It is preferable that the range of the intermediate portion where the spiral elements come to contact with each other is 380°±20°. Further, the center portion covering the range defined by a winding angle (Y) according to the below equation is provided with the relief;
Y=a
(
X
−1)
Where Y is a spiral winding angle, X is a winding turn of the spiral elements, and a constant a is a given number of more than 0 (including 0), but not more than 64, more preferably a number of not less than 6, but not more than 48. Even if a=0 and, therefor, Y=0, the relief is provided within a certain amount of the range of 0 degree where both of the spiral elements come to contact with each other in case that the relief is not provided.


REFERENCES:
patent: 4579512 (1986-04-01), Shiibayashi et al.
patent: 57-62988 (1982-04-01), None
patent: 0013184 (1983-01-01), None
patent: 0012187 (1984-01-01), None
patent: 0164589 (1991-07-01), None
patent: 58-13184 (1993-01-01), None

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