Abstract:
Contact noise occurring continuously in a hermetic electrically driven compressor is reduced.  
     A stopper  106  has a protrusion  106 A projecting along the vertical direction at the inner circumferential side formed by draw forming. If vibration or impact is applied to a electrically driven compressor body  107  from outside during operation of the electrically driven compressor body  107 , the upper end portion of a crankshaft  105  prevents continuous rotary motion along the inner circumferential side of the stopper  106 . As a result, occurrence of noise can be reduced.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a hermetic electrically driven compressor used in refrigerator, freezer, air conditioner, dehumidifier, etc.  
         BACKGROUND OF THE INVENTION  
         [0002]    A conventional hermetic electrically driven compressor comprises an enclosed container, and motor elements and compressor elements included in this enclosed container. Such conventional hermetic electrically driven compressor (hereinafter called compressor) is disclosed, for example, in Japanese Laid-open Patent No. H11-303740 or U.S. Pat. No. 5,118, 263.  
           [0003]    A conventional compressor is described below while referring to the drawing.  
           [0004]    [0004]FIG. 4 shows a compressor  10 , in which an enclosed container  20  is formed of an upper case  20 A and a lower case  20 B joined by welding or the like at mutual open edges.  
           [0005]    A electrically driven compressor body (hereinafter called compressor body)  30  is elastically supported and contained in this enclosed container  20  by way of a plurality of elastic support devices  40 . A motor element  50  is disposed in the upper part in the enclosed container  20 , and includes a stator  60  and a rotator  70 . A compressor element  80  is disposed in the lower part in the enclosed container  20 . A crankshaft  90  for coupling the compressor element  80  and motor element  50  is provided on the rotator  70 .  
           [0006]    A stopper  100  for inserting the upper end portion of the crankshaft  90  is disposed in the upper part in the enclosed container  20 .  
           [0007]    In the compressor configured in this manner, its operation is described below. The upper end portion of the crankshaft  90  is inserted into the center of the inside of the stopper  100  fitted to the upper part in the enclosed container  20 .  
           [0008]    Thus, when transporting the compressor  10 , the compressor body  30  is prevented from swinging to contact with the inside of the enclosed container  20 . As a result, the compressor body  30  is protected.  
           [0009]    In the conventional structure, the condition of mounting and fixing the compressor  10  to the refrigerator includes the following. In addition to the hardness and mounting condition of the vibration absorbing rubber prevent transmission of vibration of the compressor  10 , the rigidity of piping connection is involved. When these mounting and fixing conditions are stronger, the enclosed container  20  is fixed more firmly.  
           [0010]    In these mounting conditions, when impact or vibration is applied from outside during operation of the compressor body  30 , the following phenomenon occurs. By the motion of the elastically supported compressor body  30 , the upper end portion of the crankshaft  90  hits against the inner circumferential side of the stopper  100 .  
           [0011]    By the rotating force of the crankshaft  90  and the friction of the inner circumferential side of the stopper  100 , the crankshaft  90  repulses, and hits against the inner circumferential side of the stopper  100  by this repulsive reaction. This state occurs repeatedly, and noise is generated due to contact by rotary motion along the inner circumference of the stopper  100 .  
           [0012]    The invention is intended to solve these conventional problems, and present a compressor capable of suppressing occurrence of noise.  
         SUMMARY OF THE INVENTION  
         [0013]    The invention presents a hermetic electrically driven compressor comprising a compressor element elastically supported in an enclosed container, a crankshaft provided with said compressor element, a motor element for driving said compressor element, and a cup-shaped stopper fixed to the inside upper part of said enclosed container and having a protrusion at its inner circumferential side, wherein the upper end portion of said crankshaft extends into said stopper. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a longitudinal sectional view of a compressor in accordance with a first exemplary embodiment of the present invention.  
         [0015]    [0015]FIG. 2 is a perspective view of a stopper of the compressor in accordance with a first exemplary embodiment of the present invention.  
         [0016]    [0016]FIG. 3 is a perspective view of upper part of enclosed container of a compressor in accordance with a second exemplary embodiment of the present invention.  
         [0017]    [0017]FIG. 4 is a horizontal sectional view of upper part of enclosed container of a compressor in accordance with a second exemplary embodiment of the present invention.  
         [0018]    [0018]FIG. 5 is a longitudinal sectional view of a conventional compressor.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Preferred embodiments of the compressor of the present invention are described below while referring to the accompanying drawings. Same parts as in the prior art are identified with same reference numerals, and detailed description is omitted. The drawings are schematic ones and they do not indicate dimensional relations of the elements.  
         [0020]    (Exemplary embodiment 1)  
         [0021]    As shown in FIG. 1, inside an enclosed container  101 , a compressor element  103  elastically supported by a spring  102 , and a motor element  104  fixed at the upper side of the compressor element  103  for driving it are provided.  
         [0022]    The compressor element  103  includes a compressor chamber  109 , and a piston  108  reciprocating in the compressor chamber  109 .  
         [0023]    A cup-shaped stopper  106  is fixed to the inside upper part of the enclosed container  101 . The upper end portion of a crankshaft  105  extends into the stopper  106 . The stopper  106  is fitted with a space to the upper end portion of the crankshaft  105  composing the compressor element  103 . The space is approximately 2-10 mm. As shown in FIG. 2, a protrusion  106 A is formed at the inner circumferential side of the stopper  106 . The protrusion  106 A projects to the inside by draw forming of the stopper  106 . The protrusion  106 A is formed in a shape of a groove along the vertical direction, and the leading end of the protrusion  106 A is formed in a curvature. Thus, the protrusion  106 A is formed integrally with the stopper  106  by draw forming. It is easy to form the protrusion, without an extra cost. In this structure, the operation is described.  
         [0024]    During operation of the compressor, due to fluctuation of compressor load or an external force appling to the enclosed container  101 , the compressor element  103  elastically supported by the spring  102  oscillates. As a result, the upper end portion of the crankshaft  105  may contact with the inner circumference of the stopper  106 . At this time, by the own rotation of the crankshaft  105 , its contact portion with the stopper  106  is moved, and continuously rotates by rubbing against the inner circumference of the stopper  106 . According to the present invention, however, the upper end portion of the crankshaft  105  collides against the protrusion  106 A, and by the reaction of this collision, it further collides against the inner circumference of the stopper  106 . As a result, occurrence of continuous rotary motion is prevented. Thus, generation of noise due to collision can be prevented, and the refrigerator or the like using the compressor of present exemplary embodiment does not give any unpleasant feeling to its user.  
         [0025]    The protrusion  106 A has a vertical groove shape. Therefore, if the compressor element  103  elastically supported by the spring  102  is moved vertically, the protrusion  106 A and the upper end side of the crankshaft  105  collide against each other securely. Further, the leading end of the protrusion is a curved surface instead of an edge, and the rigidity of the protrusion is enhanced. As a result, if the protrusion  106 A collides against the leading end of the crankshaft  105 , it is not deformed.  
         [0026]    (Exemplary embodiment 2)  
         [0027]    Exemplary embodiment 2 is described while referring to FIG. 1 and FIG. 4.  
         [0028]    A compressor element  103  is elastically supported by springs  102  provided in supporting parts  110 A,  110 B,  110 C, and  110 D. Line segment A-A′ shown in FIG. 4 shows the direction of reciprocal motion of the piston. Line segment B-B′ shows nearly the center between the supporting parts  110 A and  110 B, and  110 C and  110 D. Line segment C-C′ indicates a line vertical to line segment A-A′ through the nearly central axis of the crankshaft  105  and stopper  106 .  
         [0029]    In the present exemplary embodiment, as compared with the compressor of exemplary embodiment 1, protrusion  106 A is formed as shown in FIG. 3 and FIG. 4. The protrusion  106 A is provided in a direction nearly vertical to the direction of reciprocal motion of the piston  108  indicated by line segment A-A′.  
         [0030]    The compressor of the present exemplary embodiment having such configuration has a cup-shaped stopper  106  fitted with a space to the upper end portion of the crankshaft  105  composing the compressor element  103 . The space is approximately 2-10 mm. The protrusion  106 A is formed at the inner circumferential side of the stopper  106 . Accordingly, by the repulsion of rotating force of the crankshaft  105 , when the upper end portion of the crankshaft  105  starts rotary motion along the inner circumference of the stopper  106 , the upper end portion of the crankshaft  105  collides against the protrusion  106 A. By the reaction of this collision, the upper end portion of the crankshaft  105  returns to the normal position of the stopper  106  fitted with a space, so that rotary motion can be prevented.  
         [0031]    The specific effect of the present exemplary embodiment is more specifically described by referring to FIG. 4. The compressor element  103  has its center of gravity near the compressor chamber  109 , and a greater load is applied to the spring  102  at the compressor chamber  109  side corresponding to the left side from line segment B-B′.  
         [0032]    On the other hand, the center of gravity of the motor element  104  is positioned near the axis of the crankshaft  105 , and a greater load is applied to the spring  102  at the anti-compressor chamber  109  side corresponding to the right side from the line segment B-B′.  
         [0033]    In particular, when starting or stopping the compressor, the vicinity of center of gravity of the compressor element  103  disposed in the lower part of the enclosed container  101  and the vicinity of center of gravity of the motor element  104  disposed in the upper part of the enclosed container  101  oscillate in turn. Consequently, a large vibration may occur, and a large vibration occurs in the direction of line segment A-A′ nearly coinciding with the linking the centers of gravity of the compressor element  103  and motor element  104 . As a result, when starting or stopping the compressor, if the spacing between the crankshaft  105  and stopper  106  is narrow, they collide against each other, and a loud impulse sound is generated. In the present exemplary embodiment, by contrast, the protrusion  106 A is provided in a direction vertical to the direction of line segment A-A′ as shown in FIG. 3. There is a relative wide space between the crankshaft  105  and stopper  106 , therefore it can lower the possibility of collision of them. That is, the present exemplary embodiment has an original effect of reducing the noise at the time of start and stop of the compressor, in particular.  
         [0034]    As explained herein, according to the present invention, continuous rotary motion occurring between the crankshaft  105  and stopper  106  can be prevented, and occurrence of noise can be reduced.  
         [0035]    The compressor of the present invention can be used widely in refrigerator, freezer, air conditioner, dehumidifier, etc.