Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
2000-11-09
2002-06-04
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S055600, C418S057000, C418S094000
Reexamination Certificate
active
06398530
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a compressor comprising a scroll compressor with a first compressor member and a second compressor member, first and second scroll ribs, respectively, of which are designed in the form of a circular involute and engage in one another such that the second compressor member can be moved in relation to the first compressor member on an orbital path about a central axis, a drive for the scroll compressor with a drive motor and an entraining unit which has an entraining member driven by the drive motor and moving on an entraining path about the central axis and an entraining member receiving means arranged on the second compressor member, wherein the entraining member receiving means can be moved in a radial direction in relation to the central axis with a radial degree of freedom in relation to the entraining member such that the second compressor member can be moved so as to abut sealingly with the second scroll rib on the first scroll rib of the first compressor member on account of the radial degree of freedom and the centrifugal forces acting on the second compressor member.
A scroll compressor of this type is known, for example, from U.S. Pat. No. 5,295,813.
The problem with these scroll compressors is that this solution is complicated to produce and, on the other hand, undesired, high, local area pressures can occur due to the flat entraining member surfaces.
SUMMARY OF THE INVENTION
The object underlying the invention is therefore to improve a compressor of the generic type in such a manner that this can be produced as simply as possible and operates as reliably as possible.
This object is accomplished in accordance with the invention, in a compressor of the type described at the outset, in that the entraining member has an entraining member surface curved convexly in a direction transverse to the central axis in a direction of rotation, that the entraining member receiving means is non-rotatably arranged in relation to the second compressor member and has an entraining surface which surrounds the entraining member in a ring shape and on which the entraining member surface bears by always acting upon it with a force only in a subsection, that during movement of the second compressor member on the orbital path the subsection acted upon with a force likewise moves on the entraining surface and that a space allowing the radial degree of freedom of the entraining member receiving means in relation to the entraining member exists between the entraining member and the entraining surface outside the subsection acted upon with a force.
The advantage of the inventive solution lies in its constructional simplicity which allows the entraining member receiving means, on the one hand, to be arranged on the second compressor member so as to no longer be rotatable but rather non-rotatable so that the rotary bearing required for this can be omitted since in the inventive solution the relative rotation is accomplished by the movement of the subsection on the entraining surface.
In addition, the inventive solution has the great advantage that it requires less parts and, in particular, only parts which are easy to machine.
A particularly simple solution from a constructional point of view provides for the entraining member receiving means to be securely arranged on the second compressor member.
In the constructionally simplest case, this is a bushing which is preferably integrally formed on the compressor member, the entraining member engaging in its inner recess.
With respect to the dimensioning of the possible radial degree of freedom it would also be conceivable to design this to be smaller than the maximum possible movements of the compressor member in a radial direction. It is, however, particularly favorable when the possible radial degree of freedom corresponds at least to the maximum deviation of the orbital path of the second compressor member from a geometrical circular path around the central axis. In this respect, the geometrical circular path around the central axis represents the ideal case of the orbital path which cannot, however, either be achieved from time to time or be maintained over a longer period on account of the manufacturing inaccuracies in the area of the scroll ribs, on account of thermal changes during operation, for example, varying temperature expansion or also on account of wear and tear and so it is to be assumed that the actual orbital path of the second compressor member deviates from the ideal geometrical circular path.
With respect to the dimensioning of the space it is particularly favorable when the space has in a radial direction an extension which corresponds at least to the maximum deviation of the orbital path from the geometrical circular path since, as a result, the space is in a position to allow the radial movements which are necessary so that the second compressor member always extends with its second scroll rib so as to lie along the first scroll rib of the first compressor member.
In a preferred embodiment the space has a dimension which is in the range of approximately 1.5‰ to approximately 15‰ of an extension of the entraining surface in a respective radial direction. Values of approximately 2‰ to approximately 10‰ are preferred.
With respect to the design of the space the most varied of solutions are conceivable. It would, for example, be conceivable for the space to become suddenly wider following the entraining member surface.
However, in order to provide for the fact that during a radial movement of the entraining member receiving means relative to the entraining member the radial movement is subject to a certain attenuation, it is preferably provided for the distance between them proceeding from the subsection acted upon with a force to become increasingly larger with increasing distance from the subsection, i.e. due to the continuous increase in the distance between the entraining member surface and the entraining surface a lubricant cushion forms close to the subsection acted upon with a force and this has to be expelled from the space during a sudden radial movement and thus a certain attenuation effect begins.
In this respect it is particularly favorable when the distance between the entraining member surface and the entraining surface on both sides of the subsection acted upon with a force increases with increasing distance from it so that a movement in a radial direction and also in the opposite direction thereto experiences a respective attenuation.
A particularly favorable solution with respect to the production of the entraining surface provides for the entraining surface to extend in a circular shape, preferably as a cylinder surface of a circular cylinder, so that during the movement of the second compressor member on the orbital path the entraining member surface moves along the entraining surface extending in a circular or cylindrical manner.
In this respect, the center point of the circle or cylinder formed by the entraining surface is preferably located on the circular path around the central axis which underlies the orbital path.
With respect to the design of the entraining unit, no further details have been given in conjunction with the preceding explanations concerning the invention. A most simple embodiment of an inventive entraining unit provides for this to have a single entraining member surface and an entraining surface associated with it. The space is preferably located between the entraining member and the entraining surface.
Another advantageous solution provides for the entraining surface associated with the entraining member surface to be arranged on an intermediate ring which, for its part, bears with an additional entraining member surface on an additional subsection of an additional entraining surface by acting upon it with a force and for an additional space contributing to the radial degree of freedom of the entraining member receiving means in relation to the entraining member to likewise exist between the intermediate ri
Bitzer Kuehlmaschinenbau GmbH
Lipsitz Barry R.
Vrablik John J.
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