Patent Publication Number: US-6663363-B2

Title: Driving pin structure for scroll compressor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a scroll compressor, and in particular to a structure of a driving pin for a scroll compressor which is capable of transmitting a rotational force by being combined with a rotating scroll. 
     2. Description of the Background Art 
     Generally, a compressor is for compressing a compressible fluid by using mechanical energy and can be divided into a reciprocating type, a scroll type, centrifugal type and a vane type, etc. 
     Unlike a reciprocating type compressor using a linear motion of a piston, a scroll type compressor (hereinafter, it is referred to as a scroll compressor) sucks, compresses and discharges gas by using a rotational body similar to a centrifugal type compressor and a vane type compressor. 
     FIG. 1 is a longitudinal sectional view illustrating the conventional scroll compressor. 
     As depicted in FIG. 1, the conventional scroll compressor includes a casing  1  filled with oil up to a certain height, a main frame  2  and a sub frame  3  respectively fixed to the upper and the lower portions of the inner circumference of the casing  1 , a driving motor  4  installed between the main frame  2  and the sub frame  3  and having a stator  4 A and a rotor  4 B, a rotational axis  5  placed so as to fit for the center of the rotor  4 B of the driving motor  4  and penetrating through the main frame  2 , a rotating scroll  6  combined with the rotational axis  5  and installed to the upper surface of the main frame  2 , a fixed scroll  7  fixed to the upper surface of the main frame  2  so as to form a plurality of compressing chambers by being coupled to the rotating scroll  6 , a high/low pressure division plate  8  installed to the upper portion of the fixed scroll  7  and dividing the inner space of the casing  1  into a suction pressure region and a discharge pressure region, and a counterflow prevention valve assembly  9  combined with the upper surface of the high/low pressure division plate  8  and preventing a counterflow of discharged gas. 
     FIG. 2 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of the conventional scroll compressor. 
     As depicted in FIG. 2, in the rotational axis  5 , a driving pin  5   a  eccentrically projects from the upper end of the rotational axis  5  in order to rotate the rotating scroll  6 , and a slide bush  10  inserted into the boss  6   b  of the rotating scroll  6  is slides over the driving pin  5   a  inserted therein. 
     In addition, a sliding hole  10   a  having a guide surface (not shown) is formed at the inner circumference of the slide bush  10 . The sliding hole  10   a  is a relatively deep hole in order to permit a sliding-contact between a sliding surface (not shown) of the driving pin  5   a  and the sliding hole  10   a.    
     In FIGS. 1 and 2, reference numeral  6   a  is a wrap of the rotating scroll  6 , reference numeral  7   a  is a wrap of the fixed scroll  7 , and reference numeral DP is a discharge pipe. 
     The operation of the conventional scroll compressor will be described hereinafter. 
     When power is applied, the rotor  4 B rotates beside the stator  4 A together with the rotational axis  5 , and the driving pin  5   a  formed at the upper portion of the rotational axis  5  eccentrically rotates together. The rotating scroll  6  connected to the driving pin  5   a  rotates by the eccentric rotation of the driving pin  5   a  over an eccentric distance. A body capacity of the plurality of compressing chambers formed by the wraps  6   a ,  7   a  of the rotating scroll  6  and the fixed scroll  7  is decreased while being moved to the center portion by the continuous rotational motion of the rotating scroll  6  Accordingly, refrigerant gas is sucked, compressed and discharged by the compressor. 
     FIG. 3 is a perspective view illustrating a load distribution of the driving pin of the conventional scroll compressor. 
     However, in the conventional scroll compressor, the rotational force of the driving motor  4  is transmitted to the rotating scroll  6  by the driving pin  5   a  engaging the slide bush  10 . As depicted in FIG. 3, because the side surface of the driving pin  5   a  contacting the slide bush  10  receives a reactive force, a bending moment M 1  according to this contact acts on the driving pin  5   a . Particularly, by the force and the moment acting on the side surface of the driving pin  5   a , a stress acts on each surface of the driving pin  5   a . The stress is especially concentrated on the start portion of the driving pin  5   a , accordingly the driving pin  5   a  may be damaged due to the stress concentration when the scroll compressor is used for a long time. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-mentioned problem, it is an object of the present invention to provide a driving pin structure for a scroll compressor which is capable of preventing a damage of a driving pin due to a stress concentration from happening by reducing a bending moment acted on the driving pin of a rotational axis. 
     In order to achieve the object of the present invention, in a scroll compressor comprising a fixed scroll having a wrap, a rotating scroll having a wrap engaged with the wrap of the fixed scroll and performing a rotational motion in a radial direction of the rotational axis of a driving device, a driving pin eccentrically formed at the rotational axis of the driving device and inserted into a boss of the rotating scroll and a bush member interposed between the boss of the rotating scroll and the driving pin, the driving pin has a length shorter than a length of the bush member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
     FIG. 1 is a longitudinal sectional view illustrating the conventional scroll compressor; 
     FIG. 2 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of the conventional scroll compressor; 
     FIG. 3 is a perspective view illustrating a load distribution of the driving pin of the conventional scroll compressor; 
     FIG. 4 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a first embodiment of the present invention; 
     FIG. 4A is a detail of the portion within the circle of FIG. 4; 
     FIG. 5 is a perspective view illustrating a load distribution of the driving pin of the scroll compressor in accordance with the first embodiment of the present invention; 
     FIG. 6 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a second embodiment of the present invention; 
     FIG. 6A is a detail of the portion within the circle of FIG. 6; 
     FIG. 7 is a longitudinal sectional view illustrating variation of a driving pin structure of the scroll compressor in accordance with the second embodiment of the present invention; 
     FIG. 7A is a detail of the portion within the circle of FIG. 7; 
     FIG. 8 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a third embodiment of the present invention; and 
     FIG. 8A is a detail of the portion within the circle of FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a driving pin structure for a scroll compressor in accordance with the present invention will be described in detail with reference to accompanying drawings. 
     FIG. 4 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a first embodiment of the present invention, and FIG. 5 is a perspective view illustrating a load distribution of the driving pin of the scroll compressor in accordance with the first embodiment of the present. 
     As depicted in FIG. 4, in a driving pin structure for a scroll compressor in accordance with a first embodiment of the present invention, a slide bush  120  is interposed in a boss  6   b  of a rotating scroll  6  forming a compressing chamber by being coupled to a fixed scroll (not shown), a driving pin  110  along a rotational axis  100  is inserted into the boss  6   b  of the rotating scroll  6 . However, a length of the driving pin  110  is shorter than a length of the slide bush (or an eccentric bush)  120 . 
     In more detail, the driving pin  110  eccentrically formed at the upper end of the rotational axis  100  is inserted into the boss  6   b  of the rotating scroll  6  in order to rotate the rotating scroll  6 . The outer circumference  111  of the driving pin  110  is operatively engaged in sliding contact with the inner circumference  121  of the slide bush  120 . 
     A sliding hole  122  is formed at the slide bush  120  so as to permit the driving pin  110  to be inserted therein. The inner circumference of the sliding hole  122  is slide-contacted with the outer circumference of the driving pin  110 . 
     The same reference numerals will be given to the same parts as the conventional art. 
     The operation effect of the driving pin structure for the scroll compressor in accordance with the first embodiment of the present invention will be described. 
     When the rotational axis  100  is rotated by the operation of a driving motor (not shown), the rotating scroll  6  eccentrically combined with the rotational axis  100  performs a rotational motion in a certain orbit. A body capacity of the plurality of compressing chambers (not shown) formed between the rotating scroll  6  and a fixed scroll (not shown) is decreased while moving consecutively to the center of the rotational motion, accordingly a refrigerant is sucked, compressed and discharged by the compressor. 
     Herein, the rotational force of the driving motor (not shown) is transmitted to the slide bush  120  through the driving pin  110  of the rotational axis  100 , the rotational force transmitted to the slide bush  120  is transmitted to the boss  6   b  of the rotating scroll  6 , accordingly the rotating scroll  6  turns centering around the driving pin  110 . 
     Herein, as depicted in FIG. 5, because a length (l 2 ) of the driving pin  110  is shorter than a length (L) of the slide bush  120 , a length of a contact portion (Sc) at which the slide bush  120  is contacted is shorter. Therefore, bending moment (M) occurred by a force (F) acting on the driving pin  110  is decreased and a stress concentration on the driving pin  110  can be effectively reduced. In more detail, the force acting on the driving pin  110  is equal, but a length (l 2 ) of the contact portion (Sc) of the driving pin  110  is relatively short and a bending moment (M 2 ) is decreased. Accordingly, the stress acting on the section of the driving pin  110  is reduced. 
     FIG. 6 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a second embodiment of the present invention, FIG. 7 is a longitudinal sectional view illustrating variation of a driving pin structure of the scroll compressor in accordance with the second embodiment of the present invention, and FIG. 8 is a longitudinal sectional view illustrating a shape and an assembly state of a slide bush and a driving pin of a scroll compressor in accordance with a third embodiment of the present invention. 
     In the meantime, similar to the driving pin structure for the scroll compressor in accordance with the first embodiment of the present invention, by reducing a contact portion of a slide bush  220  and a driving pin  210  in a driving pin structure for a scroll compressor in accordance with a second embodiment of the present invention, a stress on the driving pin  210  can be reduced. Accordingly, a damage of the driving pin  210  due to the stress concentration can be reduced. 
     In more detail, as depicted in FIG. 6, in the driving pin structure for the scroll compressor in accordance with the second embodiment of the present invention, an extended portion  212  having a diameter (D 2 ) smaller than a diameter (D 1 ) of the driving pin  210  is formed extending from the upper end portion of the driving pin  210 . Unlike the driving pin structure in accordance with the first embodiment of the present invention, driving pin  210  is provided with the extended portion  212 . However, a length (l 3 ) of a contact portion (Sc) at which the driving pin  210  and the slide bush  220  are contacted is shorter, a bending moment acting on the driving pin  210  is decreased, and a stress concentration on the driving pin  210  can be effectively reduced. 
     In addition, as depicted in FIG. 7, as a variation of the driving pin structure for the scroll compressor in accordance with the second embodiment of the present invention, the inner diameter D 4  of the inner circumference  322  of a slide bush  320  corresponding to an extended portion  312  formed at the upper end of the driving pin  310  is larger than the inner diameter D 3  of the slide bush  320  corresponding to the driving pin  310 . In that case, a length of a contact portion (Sc) of the driving pin  310  and the slide bush  320  is shorter, a bending moment acting on the driving pin  310  is decreased, and a stress concentration on the driving pin  310  can be effectively reduced. 
     In FIG. 8, in a driving pin structure for a scroll compressor in accordance with a third embodiment of the present invention, a non-contact portion (Sc), e.g., not contacting a slide bush  420  is formed at the end of the driving pin  410 . Since a contact portion (Sc) of the driving pin  410  and the slide bush  420  is decreased, a bending moment acting on the driving pin  410  is reduced and a stress concentration on the driving pin  410  can be effectively reduced.