Abstract:
The purpose of the present invention is to provide a scroll fluid machine, the reliability of which is ensured and which can be manufactured with high productivity. The present invention provides a scroll fluid machine comprising: a stationary scroll having a spiral wrap upstanding therefrom; an orbiting scroll provided facing the stationary scroll and orbiting; a casing provided outside the orbiting scroll; a drive shaft for causing the orbiting scroll to orbit; an orbiting bearing for transmitting the rotational movement of the drive shaft to the orbiting scroll; and a plurality of rotation prevention mechanisms for preventing the orbiting scroll from rotating. The scroll fluid machine is characterized in that: the rotation prevention mechanisms have crankshafts and also have crank bearings for supporting the crankshafts; and the gap between each of the crankshafts and the corresponding one of the crank bearings is set to be greater than the gap between the drive shaft and the orbiting bearing.

Description:
TECHNICAL FIELD 
       [0001]    Technical Field 
         [0002]    The present invention relates to a scroll fluid machine. 
         [0003]    Background Art 
         [0004]    Patent Literature 1 discloses a background art of this technical field. Patent Literature 1 describes a scroll fluid machine using a pin crank as a rotation prevention mechanism, in which the pin crank is fitted into a bearing housing with a gap larger than normal gap therebetween, and is supported with an elastic body having a large frictional force, such as rubber, interposed therebetween. 
       CITATION LIST 
     Patent Literature 
       [0005]    PATENT LITERATURE 1: JP-A-61-182401 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    Since the scroll fluid machine described in Patent Literature 1 keeps the bearing in a movable state, the bearing is moved during operation. Hence, reliability and life of the bearing cannot be improved. On the other hand, if the bearing is fixed, an orbiting scroll needs to be located with high accuracy to improve reliability and life of the bearing. Hence, productivity of the parts is lowered. 
         [0007]    The present invention has been made in view of the above problem of the conventional technique, and an object of the invention is to provide a scroll fluid machine that ensures reliability, and also improves productivity. 
       Solution To Problem 
       [0008]    To solve the above problem, the present invention provides a scroll fluid machine including: a stationary scroll in which a spiral lap part is installed; an orbiting scroll that is provided opposite to the stationary scroll and orbits; a casing that is provided outside the orbiting scroll; a drive shaft that makes the orbiting scroll orbit; an orbiting bearing that transmits a rotational movement of the drive shaft to the orbiting scroll; and multiple rotation prevention mechanisms that prevent rotation of the orbiting scroll, characterized in that: the rotation prevention mechanism has a crankshaft and a crank bearing that supports the crankshaft; and a gap between the crankshaft and the crank bearing is made larger than a gap between the drive shaft and the orbiting bearing. 
       Advantageous Effects of Invention 
       [0009]    The present invention can provide a scroll fluid machine that ensures reliability, and also improves productivity. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a cross-sectional view of a scroll fluid machine of Embodiment 1 of the present invention. 
           [0011]      FIG. 2  is a schematic drawing of related parts of the scroll fluid machine of Embodiment 1 of the present invention. 
           [0012]      FIG. 3  is a schematic drawing of related parts of a scroll fluid machine of Embodiment 2 of the present invention. 
           [0013]      FIG. 4  is a schematic drawing of related parts of a scroll fluid machine of Embodiment 3 of the present invention. 
           [0014]      FIG. 5  is a schematic drawing of related parts of a scroll fluid machine of Embodiment 4 of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
       Embodiment 1 
       [0016]      FIG. 1  is a cross-sectional view of an overall structure of a scroll fluid machine of Embodiment 1. A casing  1  holds bearings, and is provided outside an orbiting scroll  3 . A stationary scroll  2  is provided in the casing  1 , and has a spiral lap part installed. The orbiting scroll  3  is driven through a drive shaft  4 , and has a spiral lap part, which forms multiple compression chambers  6  with the lap part of the stationary scroll  2 , installed manner opposite to the stationary scroll  2 . 
         [0017]    The orbiting scroll  3  orbits by receiving, through an orbiting bearing  5  held by the orbiting scroll  3 , rotational movement from the drive shaft  4  having an eccentric part on its tip end side. The orbital movement allows fluid to flow from the compression chamber  6  formed on the outside toward the compression chamber  6  formed on the center side, and compresses the fluid by reducing its volume. 
         [0018]    The orbiting scroll  3  has multiple rotation prevention mechanisms (rotation prevention cranks) for preventing rotation of the orbiting scroll  3  during its orbital movement. The rotation prevention mechanism includes a rotation prevention crankshaft  7 , a casing side-rotation prevention crank bearing  8  attached to the casing  1 , and an orbiting scroll side-rotation prevention crank bearing  9  attached to the orbiting scroll  3 . 
         [0019]    The rotation prevention crankshaft  7  and the orbiting scroll side-rotation prevention crank bearing  9  are fixed to the orbiting scroll  3 . Hence, the rotation prevention crankshaft  7  does not move inside the orbiting scroll side-rotation prevention crank bearing  9  after assembly, and reliability can be ensured. The rotation prevention crankshaft  7  is fastened by a fastening member  10  to the casing side-rotation prevention crank bearing  8  provided in the casing  1 , with a gap therebetween, from the casing  1  side opposite to the orbiting scroll  3 . At this time, of the orbiting bearing  5 , an orbiting bearing outer race  5   a  and orbiting bearing rolling elements  5   b  are fixed to the orbiting scroll  3 , an orbiting bearing inner race  5   c  is fixed to the drive shaft  4 , and the parts are combined when fastening the rotation prevention crankshaft  7 . 
         [0020]    Note that although the rotation prevention crankshaft  7  is fixed by the orbiting scroll side-rotation prevention crank bearing  9  and fastened to the casing side-rotation prevention crank bearing  8  with a gap therebetween in the embodiment, instead, the rotation prevention crankshaft  7  may be fixed to the casing side-rotation prevention crank bearing  8  and fastened to the orbiting scroll side-rotation prevention crank bearing  9  with a gap therebetween. That is, the rotation prevention crankshaft  7  is fixed by one crank bearing, and fastened to the other crank bearing with a gap therebetween. 
         [0021]    Also, although the rotation prevention crankshaft  7  is fastened by the fastening member  10  to the casing side-rotation prevention crank bearing  8  from the casing  1  side in the embodiment, it may be fastened to the orbiting scroll side-rotation prevention crank bearing  9  from the orbiting scroll  3  side. 
         [0022]    The gap between the rotation prevention crankshaft  7  and the casing side-rotation prevention crank bearing  8  will be described with reference to  FIG. 2 . 
         [0023]      FIG. 2  is a schematic assembly drawing of parts related to Embodiment 1. In  FIG. 2 , ε 1  is the amount of eccentricity of the drive shaft  4  required to make the orbiting scroll  3  orbit. Meanwhile, ε 2  is the amount of eccentricity of the rotation prevention crankshaft  7 . L is the distance between the drive shaft  4  and the center of the casing side-rotation prevention crank bearing  8 , and is equivalent to a distance  1  between the center of the orbiting bearing  5  and the center of the orbiting scroll side-rotation prevention crank bearing  9 . Additionally, as indicated by Expression 1, the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7  is made larger than a gap between the orbiting bearing inner race  5   c  and the orbiting bearing rolling elements  5   b.    
         [0000]      (φ D   2   −φd   2 )&gt;(φ D   1   −φd   1 )   (Expression 1)
 
         [0024]    At this time, an orbiting radius ε 2 ′ of the rotation prevention crank is the distance from a center A-A′ of the casing side-rotation prevention crank bearing  8  to a center B-B′ of the orbiting scroll side-rotation prevention crank bearing  9 , and is therefore expressed by the following Expression 2. 
         [0000]      ε 2 ′=ε 1 ±(φ D   1   −φd   1 )/2+( L− 1)=ε 1 ±(φ D   1   −φd   1 )/2   (Expression 2)
 
         [0025]    According to Expression 2, the orbiting radius ε 2 ′ of the rotation prevention crankshaft  7  is not influenced by the amount of eccentricity ε 2  of the rotation prevention crankshaft  7 . 
         [0026]    Here, if the orbiting radius ε 2 ′ of the rotation prevention crankshaft  7  is influenced by the amount of eccentricity ε 2  of the rotation prevention crankshaft  7 , an excessive load is applied on the rotation prevention crankshaft  7  unless the amount of eccentricity ε 2  of the rotation prevention crankshaft  7  is designed with high accuracy. Accordingly, in order to improve reliability and life of the rotation prevention crankshaft  7 , accuracy of the amount of eccentricity ε 2  of the rotation prevention crankshaft  7  needs to be increased, and therefore productivity is lowered. 
         [0027]    Meanwhile, in the embodiment, the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7 , and the gap between the orbiting bearing inner race  5   c  and the orbiting bearing rolling elements  5   b  are designed to satisfy Expressions 1 and 2. Hence, both productivity, and reliability and life of the rotation prevention crankshaft  7  can be achieved. 
         [0028]    According to (Expression 1) and (Expression 2), the following (Expression 3) is true. 
         [0000]      |φ D   2   −φd   2 |/2&gt;|ε 2 ′−ε 1 |  (Expression 3)
 
         [0029]    Specifically, the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7  is larger than the difference between the amount of eccentricity of the drive shaft  4  and the orbiting radius of the rotation prevention crankshaft  7 . 
         [0030]    As has been described, in the embodiment, since the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7  is set to satisfy Expressions 1 and 3, the orbiting radius ε 2 ′ of the rotation prevention crankshaft  7  is not influenced by the amount of eccentricity ε 2  of the rotation prevention crankshaft  7 . Hence, reliability of the scroll fluid machine can be ensured even if the amount of eccentricity ε 2  of the rotation prevention crankshaft  7  is not highly accurate. 
         [0031]    Also, since this relaxes the tolerance of a size φd 2  and amount of eccentricity ε 2  of the rotation prevention crankshaft  7 , the rotation prevention crankshaft  7  need not be machined with high accuracy. Hence, productivity can be improved. Additionally, since the gap is wide, assembly can be facilitated. 
         [0032]    Also, unlike Patent Literature 1, the rotation prevention crankshaft  7  is fixed by the orbiting scroll side-rotation prevention crank bearing  9 , and the rotation prevention crankshaft  7  is fastened by the fastening member  10  to the casing side-rotation prevention crank bearing  8  from the casing  1  side in the embodiment. Hence, the whole bearing is not movable even after assembly, whereby reliability can be maintained. 
       Embodiment 2 
       [0033]    Embodiment 2 of the present invention will be described with reference to  FIG. 3 . The same configurations as Embodiment 1 are assigned the same reference signs, and descriptions thereof will be omitted. 
         [0034]    This embodiment is characterized in that in a scroll fluid machine similar to Embodiment 1, not only the dimensional relation of the aforementioned Expression 1 is satisfied, but also locating holes for locating an orbiting scroll  3  with respect to a casing  1  are provided. To be specific, the embodiment is characterized in that a locating hole  11  is provided in the casing  1 , and a locating hole  12  is provided in the orbiting scroll  3  as shown in  FIG. 3 . 
         [0035]    This makes it easy to locate the orbiting scroll  3  with respect to the casing  1  by using a locating pin  13 , for example, when fastening a rotation prevention crankshaft  7 . Accordingly, as compared to a case of not locating the orbiting scroll  3  by use of this structure, it is possible to prevent movement of the orbiting scroll  3  within a gap between an orbiting bearing inner race  5   c  and orbiting bearing rolling elements  5   b,  and a gap between a casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7 . 
         [0036]    In other words, in the embodiment, the orbiting scroll  3  is located with respect to the casing  1  by use of the locating holes  11 ,  12  and the locating pin  13 , instead of the rotation prevention crankshaft  7 . That is, the locating function is assigned not to the rotation prevention crankshaft  7 , but to the locating holes  11 ,  12  and the locating pin  13 . 
         [0037]    To be specific, a clearance between the centers (radial or circumferential) of the locating holes  11 ,  12  after assembly is made smaller than the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7 . 
         [0038]    This can ensure accuracy of locating, even if an amount of eccentricity ε 2  of the rotation prevention crankshaft  7  is not highly accurate. Hence, as in the case of Embodiment 1, the rotation prevention crankshaft  7  need not be machined with high accuracy, and productivity can be improved. Additionally, since the gap is wide, assembly can be facilitated. 
         [0039]    Here, if the locating holes are provided on the radially inner side of a sliding surface between the casing I and the orbiting scroll  3 , the locating hole  11  on the orbiting scroll  3  side needs to be closed to seal a compression chamber  6  after alignment This hinders productivity improvement. In the embodiment, the locating holes  11 ,  12  are provided on the radially outer side of the sliding surface between the casing  1  and the orbiting scroll  3 , to improve productivity. 
         [0040]    As has been described, according to the embodiment, the orbiting scroll  3  can be located by use of the locating holes  11 ,  12  and the locating pin  13 , and the amount of eccentricity of the orbiting scroll  3  can be defined regardless of the gap between the casing side-rotation prevention crank bearing  8  and the rotation prevention crankshaft  7 . Hence, in addition to the effects described in Embodiment 1, the gap that may cause leakage of compressed air can be minimized while preventing contact between the stationary scroll  2  and the spiral lap part of the orbiting scroll  3 , so that reliability and performance can be improved. 
         [0041]    Note that although the locating pin  13  is inserted from the casing  1  side in the embodiment, the configuration is not limited to this, and the locating pin  13  may be inserted from the orbiting scroll  3  side for assembly. 
       Embodiment 3 
       [0042]    Embodiment 3 of the present invention will be described with reference to  FIG. 4 . The same configurations as Embodiments 1 and 2 are assigned the same reference signs, and descriptions thereof will be omitted. 
         [0043]    This embodiment is characterized in that in a scroll fluid machine similar to Embodiment 2, multiple pairs of the aforementioned locating hole  11  and locating hole  12  are provided. To be specific, the embodiment is characterized in that multiple locating holes  11  are provided in a casing  1 , and multiple locating holes  12  are provided in an orbiting scroll  3  as shown in  FIG. 4 . 
         [0044]    Here, if there was only one each of the locating holes  11 ,  12 , the orbiting scroll  3  may he shifted about the locating holes in the rotation direction. Meanwhile, since there are at least two of the locating holes in the embodiment, shifting in the rotation direction can be prevented, and the orbiting scroll  3  can be located with even higher accuracy than Embodiment 2. Hence, it is possible to suppress deviation of the orbiting radius of the multiple rotation prevention mechanisms, so that load applied on the rotation prevention mechanisms can be reduced, and also reliability can be improved. 
         [0045]    As has been described, in the embodiment, not only can the orbiting scroll  3  be located, but also the position thereof in the rotation direction can he determined easily. Hence, as compared to Embodiment 2, reliability and performance can be improved even more. 
         [0046]    Note that although a locating pin  13  is inserted from the casing  1  side in the embodiment, the configuration is not limited to this, and the locating pin  13  may he inserted from the orbiting scroll  3  side for assembly. 
       Embodiment 4 
       [0047]    Embodiment 4 of the present invention will be described with reference to  FIG. 5 . The same configurations as Embodiments 1 to 3 are assigned the same reference signs, and descriptions thereof will be omitted. 
         [0048]    This embodiment is characterized in that in a scroll fluid machine similar to Embodiment 3, one of the aforementioned locating holes  12  provided in a casing  1  is formed in an end surface of a drive shaft  4 . To be specific, the embodiment is characterized in that the locating hole  12  is provided in the end surface of the drive shaft  4 , and a locating hole  11  is provided in an end surface of an orbiting scroll  3  as shown in  FIG. 5 . 
         [0049]    To improve reliability and performance of a scroll fluid machine, it is necessary to increase accuracy not only when aligning lap parts of a stationary scroll  2  and the orbiting scroll  3 , but also when aligning the drive shaft  4  and an orbiting bearing  5 . In particular, the drive shaft  4  and the orbiting bearing  5  need to be aligned within an area where an eccentric part of the drive shaft  4  orbits. 
         [0050]    Against this background, in the embodiment, the locating hole  12  is provided in the end surface of the eccentric part of the drive shaft  4 . This facilitates alignment of a shaft center of an inner race  5   c  and the center of an outer race  5   a  of the orbiting bearing  5 , regardless of an amount of eccentricity ε 1  of the drive shaft  4 . 
         [0051]    As has been described, according to the embodiment, the drive shaft  4  and the orbiting bearing  5  can be easily aligned with high accuracy, and load applied on the orbiting bearing  5  can be reduced. Hence, as compared to Embodiment 3, reliability of the orbiting bearing can be improved even more. 
         [0052]    Although embodiments have been described above, the present invention is not limited to the above embodiments, and includes various modifications. For example, while the above embodiments are described in detail for the sake of a better understanding of the invention, the invention does not necessarily have to include all of the above-described configurations. The configuration of an embodiment may be partially replaced with the configuration of another embodiment, or the configuration of an embodiment may be added to the configuration of another embodiment. A different configuration may be added to, deleted from, or replaced with a part of the configuration of each embodiment. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  casing 
           2  stationary scroll 
           3  orbiting scroll 
           4  drive shaft 
           5  orbiting bearing 
           5   a  orbiting bearing outer race 
           5   b  orbiting bearing rolling elements 
           5   c  orbiting bearing inner race 
           6  compression chamber 
           7  rotation prevention crankshaft 
           8  casing side-rotation prevention crank bearing 
           9  orbiting scroll side-rotation prevention crank bearing 
           10  fastening member 
           11  locating hole 
           12  locating hole 
           13  locating pin