Abstract:
The invention aims to provide a scroll fluid machine which has auxiliary cranks divided into two separate crank members connected by pressure fitting in the process of assembling of the scroll machine. Each of the auxiliary cranks for regulating the motion of the revolving scroll is divided into a revolving scroll side crank member and a stationary scroll side crank member, the crank members are configured such that one of the crank members can be pressed into the other crank member, and both of the crank members are connected to compose a one-piece auxiliary crank when both of the scrolls are assembled.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a scroll fluid machine for compressing, expanding, or pressure feeding fluid and an assembling method thereof.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    In a scroll fluid machine, three sets of mechanism for preventing rotation of the revolving scroll comprising auxiliary crank are placed near the periphery of the scrolls at equal circumferential spacing in order to prevent rotation of the revolving scroll and allow it to revolve.  
           [0003]    It is necessary that the mirror-surfaces of both of the revolving and stationary scrolls are parallel to each other, since if they are not parallel to each other, hermeticity of the closed compression pocket formed by the wraps of the scrolls as the revolving scroll revolves is damaged due to the deflection of the mirror-surfaces. Therefore, each scroll should be supported by means of the auxiliary cranks of the rotation preventing mechanisms so that both of the mirror-surfaces are parallel.  
           [0004]    In Japanese Patent No. 2562581 is disclosed a scroll compressor which has three sets of mechanism for preventing rotation of the revolving scroll capable of adjusting the gap between the top surface of wrap and the mating mirror-surface by rotating the double nuts which determine the position of the auxiliary crank of each of the rotation preventing mechanisms relative to the bearing provided in the bearing housing of the stationary scroll.  
           [0005]    Therefore, the gap between the top surface of wrap and the mating mirror surface is adjusted after the stationary scroll and revolving scroll are assembled, and the adjusting must be performed for three auxiliary cranks. which means the adjusting is intricate and time-consuming.  
           [0006]    If each of the auxiliary cranks is divided into two parts, a stationary scroll side crank member and a revolving scroll side crank member, one of the crank members being able to be pressed into the other crank member to connect them to be compose a one-piece auxiliary crank, and both of the crank members installed respectively in the both of the scrolls are pressed into one-piece when both of the scrolls are assembled, said adjustment procedure of the gap after assembling both of the scrolls is eliminated. In this case, if both of the crank members are so configured that the distance between the mirror-surfaces of both of the scrolls can be adjusted by press-in depth of one of the crank member into the other crank member, dimensional deviation of component parts can be cancelled by the press-in depth.  
           [0007]    When the dimensions of the component parts are accurate, the scrolls are assembled without undue deflection of the scroll plate by preparing a standard auxiliary crank having the length corresponding to the distance between the mirror-surfaces of both of the scrolls. But, when there is dimensional deviation of the component parts, the scroll plates may be deflected when both of the scrolls are assembled if said length of the standard auxiliary crank does not correspond to the distance between the mirror-surfaces at all of the rotation prevention mechanisms.  
           [0008]    The dimensional deviation varies depending on production lots, so that many auxiliary cranks of different size (tolerance) must be prepared, resulting in complicated production control.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention was made in light of the problem mentioned above, and an object of the invention is to provide an auxiliary crank composed of a pair of crank members capable of being connected by pressing-in one of the crank members to the other crank member to compose a one-piece auxiliary crank and a scroll fluid machine having said auxiliary crank.  
           [0010]    Another object of the present invention is to provide a scroll fluid machine which does not need the adjustment of the distance between the mirror-surfaces after the revolving scroll and stationary scroll are assembled.  
           [0011]    The present invention proposes a scroll fluid machine having a revolving scroll side connected to a stationary scroll side by means of auxiliary cranks for regulating the motion of the revolving scroll, wherein each of said auxiliary crank comprises a revolving scroll side crank member and a stationary scroll side crank member, and both of the crank members are connected by pressing one of the crank members into the other crank member to compose a one-piece auxiliary crank.  
           [0012]    Here, “revolving scroll side” and “stationary scroll side” refer not only to the revolving scroll and stationary scroll respectively. Referring to FIG. 1, said revolving scroll side includes, for example, the scroll  12  having a revolving scroll wrap  12   a  and a mirror-surface  12   c , and moving components attached to and revolving together with the revolving scroll  12 .  
           [0013]    Said stationary scroll side includes, for example, the stationary scroll  11  having a stationary scroll wrap  11   a  and a mirror-surface  11   c,  and the scroll housing  13  surrounding the revolving scroll  12  and fixed to the stationary scroll  11 .  
           [0014]    According to the present invention, the auxiliary crank is divided into two crank members of the revolving scroll side and stationary scroll side, and both of the crank members are connected to compose a one-piece crank by pressing one of the crank members into the other crank member.  
           [0015]    Therefore, even if there is dimensional deviation of component parts, the length of the auxiliary crank can be adjusted by adjusting the press-in depth of one of the crank members into the other crank member in accordance with the distance between the mirror-surfaces of both of the scrolls, that is, in accordance with the scroll wrap height.  
           [0016]    To be more specific, when auxiliary cranks having different length are needed for maintaining the even distance between the mirror-surfaces of both of the scrolls at all of the three rotation preventing mechanisms, if the auxiliary cranks having the same length is used, deflection occurs in the scroll plates.  
           [0017]    By adjusting the press-in depth of one of the crank members to connect both of the crank members, dimensional deviation of the component part can be absorbed or cancelled. Therefore, it is not necessary to prepare auxiliary cranks of different dimension (tolerance), and dimensional deviation of component parts can be circumvented by adjusting the press-in depth.  
           [0018]    In this way, auxiliary cranks each having the length capable of canceling dimensional deviation of component parts which differ depending on rotation preventing mechanisms and production lots are composed, resulting in a reduction of costs.  
           [0019]    When scrolls with another scroll wrap height is to be assembled, the auxiliary cranks having the length corresponding to the wrap height are needed. This is also acieved by adjusting press-in depth of one of the crank member into the other crank member to compose a one-piece auxiliary crank.  
           [0020]    It is an effective means of the present invention that pairs of crank members are selected in accordance with scroll wrap height and one of each pair of crank members is pressed into the other crank member to compose an auxiliary crank corresponding to the wrap height.  
           [0021]    With the technical means like this, by preparing one or both of the crank members of various length and selecting the crank members, an auxiliary crank having the length corresponding to scroll wrap height can be composed.  
           [0022]    It is also an effective means of the present invention that both of the crank members are pressed into both side of a connector piece(spacer) to compose a one-piece auxiliary crank having the length corresponding with scroll wrap height.  
           [0023]    With the technical art like this, the length of the auxiliary crank can be changed largely by changing the thickness of the spacer.  
           [0024]    It is also an effective means of the present invention that press-in depth of at least one of the crank members into said connector piece(spacer) is varied to compose a one-piece auxiliary crank having the length corresponding with scroll wrap height.  
           [0025]    With the technical art like this, it is not necessary to prepare a variety of pair of crank members. It is enough to prepare at least one of the crank members of various lengths and change said one of the crank members to correspond to scroll wrap height.  
           [0026]    It is also an effective means of the present invention that a bolt for fixing one of the crank members with the other crank member is provided, and both of the crank members are fixed by said bolt to compose auxiliary crank having the length corresponding with scroll wrap height.  
           [0027]    With the technical art like this, by preparing one of the crank members of various length and selecting the one which corresponds to the height of the scroll wrap, it becomes unnecessary to prepare many auxiliary cranks of various length and cost reduction is achieved.  
           [0028]    The auxiliary crank according to the present invention is characterized in that it is composed of a pair of crank members capable of being connected by pressing in one of the pair of crank members, and a plurality of at least one of the crank members of different height are prepared so that said one of the crank members can be selected.  
           [0029]    By preparing a plurality of one of the crank members of different length and selecting one of the crank members in order to correspond to the height of the scroll wrap, it is not necessary to prepare many auxiliary crank of different length, resulting in a reduction of costs.  
           [0030]    Further, the method of assembling a scroll fluid machine is characterized in that each of the auxiliary cranks is divided in two crank members, each crank member is mounted on the revolving side and stationary scroll side respectively, and both of the scrolls are assembled by shifting one of the scroll side in the direction of the axis of the crank member so that one of the crank members is pressed into the other crank member to be connected to compose a one-piece auxiliary crank.  
           [0031]    According to the invention, each of the auxiliary cranks is divided into a revolving scroll side crank member and a stationary scroll side crank member, and both of the crank members are connected in the assembling process of the scroll machine by shifting the revolving or stationary scroll side in the direction of the axis of the crank members. Thus a one-piece auxiliary crank is composed in the scroll machine when both of the scrolls are assembled. Therefore, it is not necessary to adjust the gap between the tip of the scroll wrap and mirror-surface after both of the scrolls are assembled. Said gap is already adjusted when both of the scrolls are assembled, as the press-in depth is adjusted in the process of assembling. In this way, a plurality(three)of auxiliary crank are composed in the scroll machine by pressing one of the crank members into the other crank member in the process of assembling the scroll machine.  
           [0032]    Therefore, according to the present invention, as the auxiliary crank is divided into a revolving scroll side crank member and a stationary scroll side crank member and both of the crank members are connected by press fitting, dimensional deviation of components parts can be cancelled by the adjustment of the depth of insertion when assembling the revolving and stationary scroll side. As a result, preparation of auxiliary cranks of various dimension is not necessary, auxiliary cranks can be composed in assembling process in accordance with dimensional deviation of component parts which differs according to production lots, and cost reduction is achieved.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 is a sectional view of an embodiment of the scroll fluid machine of the present invention.  
         [0034]    [0034]FIG. 2 is an illustration for explaining the method of assembling the revolving scroll side with stationary scroll side mounted with revolving scroll side crank members and stationary scroll side crank members respectively.  
         [0035]    [0035]FIG. 3 is another illustration for explaining the method of assembling the revolving scroll side with stationary scroll side mounted with revolving scroll side crank members and stationary scroll side crank members respectively.  
         [0036]    [0036]FIG. 4 is a side view of an embodiment of the auxiliary crank consisting of three component parts to be connected to compose an auxiliary crank including a partially sectional view.  
         [0037]    [0037]FIG. 5 shows sectional views of two embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank.  
         [0038]    [0038]FIG. 6 shows sectional views of another three embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank.  
         [0039]    [0039]FIG. 7 shows sectional views of still another three embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank.  
         [0040]    [0040]FIG. 8 shows an embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt.  
         [0041]    [0041]FIG. 9 shows another embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt.  
         [0042]    [0042]FIG. 10 shows still another embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]    A preferred embodiment of the present invention will now be detailed with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, relative positions and so forth of the constituent parts in the embodiments shall be interpreted as illustrative only not as limitative of the scope of the present invention.  
         [0044]    [0044]FIG. 1 is a sectional view of an embodiment of the scroll fluid machine of the present invention. In the drawing, a scroll fluid machine  1  is composed of a revolving scroll  12  having a wrap  12   a , a stationary scroll  11  having a wrap  11   a  meshing with said wrap  12   a , a scroll housing  13  surrounding said revolving scroll  12  and fixed to said stationary scroll  11 , and a motor housing  14  incorporating a motor  2  to drive said revolving scroll  12 .  
         [0045]    The circular stationary scroll  11  is provided with a discharge hole  11   d  in the center of the mirror-surface  11   c  thereof, the hole  11   d  communicating with a outlet port  16 . The stationary scroll  11  have a stationary scroll wrap  11   a  extending spirally outwardly from the vicinity of said discharge hole  11   d . A tip seal  34  made of fluorine contained resin having self-lubricating property is received in the groove defined in the tip of the wrap  11   a.    
         [0046]    Three bearing housing bosses  11   b  are formed equally spaced with a central angle of 120° near the periphery of the stationary scroll. Each bearing housing boss  11   b  has an opening  11   g,  in which ball bearings  8 ,  9  are received. The lower part  22   a  of a crank member  22  is fit in the inner races of the bearing  8  and  9  and a bolt  38  is screwed in the female screw  22   b  of the crank member  22  to fix the inner races thereto via a washer  20 .  
         [0047]    The revolving scroll  12  has a revolving scroll wrap  12   a  extending spirally to mesh with the stationary scroll wrap  11   a.  A tip seal  35  made of fluorine contained resin having self-lubricating property is received in the groove defined in the tip of the wrap  12   a.    
         [0048]    Three bearing housing bosses  12   b  are formed near the periphery of the revolving scroll corresponding to those of the stationary scroll. Each bearing housing bosses  12   b  has an opening  12   g,  in which ball bearings  6 ,  7  are received.  
         [0049]    The upper part  21   a  of a crank member  21  is fit in the inner races of the bearing  6  and  7  and a bolt  37  is screwed in the female screw  21   b  of the crank member  21  to fix the inner races thereto via a washer  19 .  
         [0050]    The end part  21   c  of the crank member  21  of the revolving scroll  12  side is pressed into the hole  22   c  of the crank member  22  of the stationary scroll  11  side to form an auxiliary crank with the center axis of the crank member  22  and that of the crank member  21  offset to compose a rotation preventing mechanism  10 .  
         [0051]    The revolving scroll  11  has a wall surrounding the stationary scroll wrap  11   a  and a dust seal  36  is received in the groove defined in the tip of the wall, the tip surface facing the mirror-surface  11   a  of the stationary scroll.  
         [0052]    A bearing housing boss  12   d  is formed on the other side of the mirror-surface  12   c  of the revolving scroll  12  in the housing hole of which is fitted a ball bearing  25 .  
         [0053]    The scroll housing  13  having a inlet port of fluid is provided with a bearing housing boss  13   d  which is fitted a ball bearing  15 . In side the scroll housing  13  and the motor housing  14  is mounted a rotation shaft  3  having a rotor  18 , and a stator  17  surrounding the rotor  18  is attached to the motor housing  14  which is fixed to the scroll housing  13  by means of bolts  23 . The stationary scroll  11  is fixed to the scroll housing  13  by means of bolts  24 .  
         [0054]    An end side of the rotation shaft  3  is supported for rotation by the motor housing  14  via a ball bearing  26  and the other end side  3   a  is supported for rotation by a ball bearing  5  in the housing hole  13   d  of the scroll housing  13 .  
         [0055]    An offset crank member part projecting from the end surface of said end side  3   a  of the rotation shaft  3  is fit in the inner race of the ball bearing  25 .  
         [0056]    In the scroll fluid machine  1  composed as described above, the revolving scroll  12  revolves as the rotation shaft  3  rotates, fluid is sucked from the inlet port  15  of the scroll housing  13  to be taken into the closed pocket formed by the wraps of the revolving and stationary scrolls. The closed pocket is transferred toward center reducing in its volume as the revolving scroll revolves and the fluid in the pocket is compressed to be discharged from the discharge hole  11   d  and then let out from the outlet port  16 .  
         [0057]    Next, the method of pressing the revolving scroll side crank member  21  into the stationary scroll side crank member  22  will be explained with reference to FIG. 2.  
         [0058]    Referring to FIG. 2, three bearing housing bosses  12   b  are provided near the periphery of the revolving scroll  12  equally spaced with center angle of 120° as mentioned before. Similarly, the stationary scroll is provided with three bearing housing bosses  11   b  corresponding to the three bearing housing bosses  12   b  of the revolving scroll  12 .  
         [0059]    Marks  11   e  are inscribed on the stationary scroll to show the position of the openings of the bearing housing bosses  11   b.  One of the marks  11   e  is on the straight line passing the centers of the stationary scroll and the opening of one of the nearing housing bosses  11   b,  other two marks are on the lines parallel to said straight line passing the centers of the openings of the other bearing housing bosses  11   b.    
         [0060]    The stationary scroll side crank member  22  has on its top the hole  22   c , the center axis of which is offset from the center axis of the lower part  22   a . A mark  22   e  is inscribed on the stationary scroll side crank member  22  on the straight line extending from the center of the lower part  22   a  (see FIG. 1) passing the center of the hole  22   c . The stationary scroll side crank members  22  are rotated so that the marks  22   e  coincide with the marks  11   e  respectively. In this state, the revolving scroll is positioned so that the end part  21   c  (see FIG. 1) of each crank member  21  matches to the opening  22   c  of the crank member  22 , then the revolving scroll  11  is pressed down so that the lower end part of each crank member  21  is pressed into the opening  22   c  of each crank member  22 .  
         [0061]    The existence of the hole  21   d  in the crank member  22  favors the pressing-in of lower end part of the crank member  21  into the opening  22   c  of the crank member  22 .  
         [0062]    Next, the method of pressing the revolving scroll side crank member  21  into the stationary scroll side crank member  22  will be explained with reference to FIG. 3. The point of difference from FIG. 2 is that assembling is performed with the motor  2  accommodated in the motor housing  14  and scroll housing  13 , and with the revolving scroll attached to the rotation shaft  3  of the motor.  
         [0063]    In this case also each of the marks  22   e  are brought to coincide with each of the marks  11   e  respectively. Then the rotation shaft  3  is set to its maximum offset position toward right in the drawing.  
         [0064]    The revolving scroll is positioned so that the lower end part  21   c  of each crank member  21  matches to the opening  22   c  of each crank member  22 , then pressing force is applied on the motor housing  14  near the periphery so that the lower end part  21   c  of each crank member  21  is pressed into the opening  22   c  of each crank member  22 . The pressing force applied on the motor housing is transmitted to the scroll housing  13 , and the wall of the scroll housing deflects to contact the top of each bolt  37  which fixes the crank member  21  to the bearing  6 ,  7 , and the revolving scroll side crank member  21  are pressed into the openings  22   c  of the stationary scroll side crank member  22 .  
         [0065]    The press-in depth of each of the crank members  21  into the hole  22   c  of each of the crank members  22  can be determined by the push-down distance of the motor housing  14 . Since the distance between the mirror-surface of the revolving scroll and that of the stationary scroll can be adjusted by controlling said press-in depth, the adjusting is simple compared with the prior art of adjusting by means of the double nuts at three places, and accurate adjusting is possible.  
         [0066]    It is preferable that the pressing force is applied on the top near the periphery  14   a  immediately above the circumferential wall  14   b  of the motor housing  14 , and that the bolt  37  are located immediately below the circumferential wall  13   b  of the scroll housing  13  with a gap of about 0.5˜1 mm between the top of the bolt  37  and the inner upper surface  13   b  of the scroll housing  13 . Further, it is preferable that the clearance between the top face  3   e  of the rotation shaft  3  and the bottom surface  12   h  of the bearing housing  12   d  of the revolving scroll  12  is larger than the press-in depth of the crank member  21  into the opening  22   c  of the crank member  22 .  
         [0067]    As a result, the top face  3   e  of the rotation shaft  3  does not contact with said bottom surface  12   h  when pressing force is applied on the periphery part  14   a  of the motor housing  14 . The pressing force is transmitted through the circumferential wall  14   b  of the motor housing  14  to the circumferential wall  13   b  of the scroll housing  13 , then to the bolt  37  of the crank member  21 , so that undue stress which induces damage of the motor does not act on the motor.  
         [0068]    According to the embodiment, each of the auxiliary cranks is divided into a revolving scroll side crank member and a stationary scroll side crank member, and both of the scrolls can be assembled so that the mirror-surface of the revolving scroll is parallel to that of the stationary scroll without the necessity of adjusting the three auxiliary cranks by means of double nuts after the assembling of the scrolls by pressing the revolving scroll side crank member into the stationary side crank member with the press-in depth adjusted.  
         [0069]    Another embodiment which is effective likewise will be explained hereunder.  
         [0070]    [0070]FIG. 4 is a side view of an embodiment of the auxiliary crank consisting of three component parts to be connected to compose an auxiliary crank including a partially sectional view. A revolving scroll side crank member  31  and a stationary scroll side crank member  32  are pressed into a connecting ring  28  to be assembled into an auxiliary crank. The shaft part  31   a  of the crank member  31  is inserted into the bearings of the revolving scroll and the shaft part  32   a  of the crank member  32  is inserted into the bearing of the stationary scroll. The shaft part  31   c  of the crank member  31  is pressed into the opening  28   c  of the connecting ring  28  and the shaft part  32   d  of the crank member  32  is pressed into the opening  28   d  of the connecting ring  28  when both of the scrolls are assembled.  
         [0071]    The length of the auxiliary crank cab be adjusted by preparing the connecting rings  28  of various height.  
         [0072]    The opening  28   c  and  28   d  may be communicated to form a through hole and the press-in depth of the crank member  31 ,  32  can be adjusted to adjust the length of the auxiliary crank.  
         [0073]    A female screw thread may be provided in the center of each of the crank member  31  and crank member  32  for fastening bearings by means of a bolt.  
         [0074]    The edge  28   a  and  28   b  of the opening  28   c  and  28   d  respectively of the connecting ring  28  are preferable to be rounded or taper-chamfered. The edge  31   b  and  32   d  of the shaft part  31   c  and  32   d  of the crank member  31  and  32  respectively are preferable to be tapered or rounded. By tapering or rounding like this, the crank members can be easily pressed-in even when the center axis of the shaft part to be pressed-in does not coincide accurately with that of the opening for receiving the shaft part.  
         [0075]    [0075]FIG. 5 shows sectional views of two embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank. FIG. 5( a ) shows the case the top edge  39 Ad of the shaft part  39 Ac to be pressed-in of the revolving scroll side crank member  39 A is rounded so that the shaft part  39 Ac can be easily pressed into the opening  40 Ac of the stationary scroll side crank member  40 A. The shaft part  39 Aa of the crank member  39 A is inserted into the bearings of the revolving scroll, and the shaft part  40 Aa of the crank member  40 A is inserted into the bearings of the stationary scroll. Female screw thread  39 Ab and  40 Ab is cut in the center of the shaft part  39 Aa and  40 Aa respectively for fastening the bearings by means of a bolt.  
         [0076]    [0076]FIG. 5( b ) shows the case the top edge  39 Bd of the shaft part  39 Bc to be pressed-in of the revolving scroll side crank member  39 B is taper-chamfered instead of being rounded as is the case with FIG. 5( a ).  
         [0077]    By tapering or rounding the top edge of the shaft part of the revolving scroll side crank member like this, the crank member can be easily pressed into the opening  40 Ac of the stationary scroll side crank member even when the center axis of the shaft part  39 Bc does not coincide accurately with that of the opening  40 Ac.  
         [0078]    [0078]FIG. 6 shows sectional views of another three embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank. In all of FIG. 6( a ), ( b ), ( c ), the edge of the opening  40 Bc of the stationary scroll side crank member  40 B is chamfered in a tapered shape ( 40 Bd), and the configuration of the crank member  40 B is the same as that of the crank member  40 A of FIG. 5 in other than that point.  
         [0079]    Concerning the revolving scroll side crank member, the top edge of the shaft part  39 Cc to be pressed-in is not rounded or taper-chamfered in the case of FIG. 6( a ), but as the edge of the opening  40 Bc of the crank member  40 B is taper-chamfered, the shaft part  39 Cc can be pressed into the opening  40 Bc with relative ease. The configuration of the crank member  39 C is the same as that of the crank member  39 A of FIG. 5.  
         [0080]    In the case of FIG. 6( b ), the crank member  39 B is used and the top edge  39 Bd of the shaft part  39 Bc to be pressed-in is taper-chamfered, so the shaft part  39 Bc can be easily pressed into the opening  40 Bc.  
         [0081]    In the case of FIG. 6( c ), the crank member  39 B is used and the top edge  39 Ad of the shaft part  39 Ac to be pressed-in is rounded, so the shaft part  39 Ac can be easily pressed into the opening  40 Bc.  
         [0082]    [0082]FIG. 7 shows sectional views of still another three embodiments of the auxiliary crank consisting of a pair of crank members to be connected to compose an auxiliary crank. In all of FIG. 7( a ), ( b ), ( c ), the edge of the opening  40 Cc of the stationary scroll side crank member  40 C is rounded( 40 Cd). and the configuration of the crank member  40 C is the same as that of the crank member  40 A of FIG. 5 in other than that point.  
         [0083]    Concerning the revolving scroll side crank member, the crank member  39 C of FIG. 6 is used as revolving scroll side crank member and top edge of the shaft part  39 Cc to be pressed-in is not rounded or tapered in the case of FIG. 7( a ), but as the edge of the opening  40 Bc of the crank member  40 B is rounded ( 40 Cd), the shaft part  39 Cc can be easily pressed into the opening  40 Bc.  
         [0084]    In the case of FIG. 7( b ), the crank member  39 B is used and the top edge  39 Bd of the shaft part  39 Bc to be pressed-in is taper-chamfered, so the shaft part  39 Bc can be easily pressed into the opening  40 Bc.  
         [0085]    In the case of FIG. 7( c ), the crank member  39 A is used and the top edge  39 Ad of the shaft part  39 Ac to be pressed-in is rounded, so the shaft part  39 Ac can be easily pressed into the opening  40 Bc.  
         [0086]    By taper-chamfering or rounding the top edge of the shaft part to be pressed-in or the edge of the opening to receive the shaft part as shown in FIGS. 5,6, and  7 , the shaft part to be pressed-in can be easily pressed into the opening to receive the shaft part even if the center axis of the shaft part does not coincide accurately with that of the opening.  
         [0087]    [0087]FIG. 8 shows an embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt. FIG. 8( a ) shows one of the crank member in a side view and the other crank member in a sectional view.  
         [0088]    The stationary scroll side crank member having the shaft part  42 Aa to be inserted into the bearings of the stationary scroll is formed into a mushroom-like shape having a cap and a stem, a hole  42 Ac is formed in the cap, the center axis of the hole being offset from that of the stem. A slit  42 Ag is cut in the cap along the center line passing the centers of the stem  42 Aa and hole  42 Ac. A screw hole  42 Ae with spot facing  42 Af is provided perpendicular to the slit  42 Ag in order to firmly clasp the shaft part  41 Ac of the revolving scroll side crank member  41 A by tightening the bolt  33  after it is inserted into the hole  42 Ac.  
         [0089]    [0089]FIG. 9 shows another embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt.  
         [0090]    The point different from FIG. 8 is that a slit  42 Bg is cut beyond the center axis of the shaft part  42 Ba through the cap and the stem(shaft part  42 Ba), although in the case of FIG. 8 the slit  42 Ag is cut only in the cap.  
         [0091]    Therefore, when the material and geometry are the same as those of FIG. 8, weaker tightening of the bolt  33  than the case of FIG. 9 is allowed for firmly clasping the shaft part  41 Ac of the revolving scroll side crank member  41 A after it is inserted into the hole  42 Ac.  
         [0092]    [0092]FIG. 10 shows still another embodiment of the auxiliary crank consisting of a pair of crank members provided with a tightening bolt.  
         [0093]    In this case, a lateral slit  42 Ch reaching near the center axis of the stem(shaft part  42 Ca) is cut in the cap of the crank member  42 C in addition to a longitudinal slit  42 Cg.  
         [0094]    Therefore, when the material and geometry are the same as those of FIG. 8 and FIG. 9, still weaker tightening of the bolt  33  than the case of FIG. 8 and FIG. 9 is allowed for firmly clasping the shaft part  41 Ac of the revolving scroll side crank member  41 A after it is inserted into the hole  42 Ac.  
         [0095]    It is allowable that the revolving scroll side crank member is pressed into the hole of the stationary scroll side crank member with the bolt  33  tightened beforehand.  
         [0096]    A female screw thread may be provided in both of the crank members in the center of the shaft part to be inserted into the bearings for fastening the bearings by means of a bolt.  
         [0097]    It is possible in the embodiments of FIGS.  4 ˜ 10  that a spacer(connector piece) is provided between both of the crank members which are pressed into both side of the spacer and the length of the auxiliary crank can be adjusted in accordance with the distance between the mirror-surfaces of both of the scrolls.  
         [0098]    It is also suitable to apply an adhesive agent at least to the shaft part to be pressed-in or to the hole to receive the shaft part in order to reinforce the connection between the crank members.  
         [0099]    Although the bearing housings bosses  12   b  are formed integral with the revolving scroll  12  as shown in FIG. 1, it is possible to prepare the bearing housing bosses separately and attach to the revolving scroll, for example, by means of bolts. In this specification, “revolving scroll side crank member” includes the crank member in both of the above cases.  
         [0100]    Further, although the bearing housing bosses  11   b  are formed integral with the stationary scroll as shown in FIG. 1, it is possible to form the bearing housing bosses in the scroll housing  13  which surrounds the revolving scroll and is fixed to the stationary scroll. In this specification, “stationary scroll side crank member” includes the crank member in both of the above cases.