Patent Publication Number: US-7708532-B2

Title: Electric compressor

Description:
TECHNICAL FIELD 
     The present invention relates to an electric compressor in which a compressing mechanism which sucks, compresses and discharge fluid and a motor which drives the compressing mechanism are accommodated in a container, and the motor is driven by a motor drive circuit. 
     BACKGROUND TECHNIQUE 
     In a conventional compressor of this kind, there is a conventional technique to lead out a lead wire of a motor toward a sealed terminal by cutting an outer periphery of a compressing mechanism to form a notch, and then, using a communication passage for refrigerant provided between the notch and a container as a wire passage for leading out a lead wire (e.g., see patent document 1). 
       FIG. 3  is a sectional view of a conventional vertical type electric compressor.  FIG. 4  is a plan view of the electric compressor shown in  FIG. 3 . 
     In  FIG. 3 , compressed refrigerant discharged to a discharge chamber  103  from a discharge hole  102  of a compressing mechanism  101  passes through a descending communication passage  104  formed in the compressing mechanism  101  and enters into a lower motor space  105 , passes through an ascending communication passage  107  provided between a hermetic container  106  and a notch formed by notching the compressing mechanism  101 , enters into an upper sealed terminal-side space  108 , and is discharged from a discharge tube  109 . 
     In  FIG. 4 , a sealed terminal  110  and a motor  111  are electrically connected to each other through a lead wire  112  passing through the ascending communication passage  107 . That is, the ascending communication passage  107  for refrigerant is also used as a wire passage. 
     [Patent Document 1] Japanese Patent Application Laid-open No. 2001-020865 
     SUMMARY OF THE INVENTION 
     According to the conventional structure, however, since the same member is used as both the wire passage of the lead wire and the communication passage for refrigerant, gas refrigerant discharged from the compressing mechanism flows around the lead wire, the lead wire is vibrated by pulsating flow, the vibrating lead wire rubs with a casting surface forming a notch of the compressing mechanism or an inner surface of the container, and there is an adverse possibility that the lead wire is damaged. 
     To prevent such a case, there are methods for protecting the lead wire using a tube, fixing the lead wire in a special manner, and improving the surface roughness of the notch by cutting the notch, but there is a problem that such methods increase the cost. 
     The present invention has been accomplished to solve the conventional problems, and it is an object of the invention to provide an electric compressor in which a lead wire leading-out connection of a motor and a communication passage for refrigerant are separated from each other, thereby preventing the lead wire from being damaged and enhancing the reliability. 
     According to the electric compressor of the present invention, it is possible to prevent a lead wire of a motor from being damaged, and to enhance the reliability. 
     DISCLOSURE OF THE INVENTION 
     A first aspect of the present invention provides an electric compressor in which a motor and a compressing mechanism are accommodated in a container, the compressing mechanism is connected to the motor through a drive shaft, the container is divided into a first space and a second space by the compressing mechanism, and the motor is disposed in the first space, wherein the second space is divided into a discharge chamber and a connection space by a division wall, a discharge hole of the compressing mechanism is in communication with the discharge chamber, a sealed terminal is disposed in the connection space, a wire passage for bringing the first space and the connection space into communication with each other is formed in an outer periphery of the compressing mechanism, and a lead wire for connecting the motor and the sealed terminal with each other is disposed in the wire passage. With this aspect, vibration of the lead wire caused by gas pulse can be suppressed, the lead wire is prevented from being damaged, and the reliability of the electric compressor can be enhanced. 
     According to a second aspect of the invention, in the electric compressor of the first aspect, a discharge port which is in communication with the first space is formed, and a communication passage for bringing the first space and the discharge chamber into communication with each other is formed in an outer periphery of the compressing mechanism. With this aspect, refrigerant discharged into the discharge chamber is introduced to the peripheries of the motor by the communication passage, the refrigerant is allowed to flow out from the container through the discharge port, and the lubricating oil can be separated from the refrigerant. Thus, it is possible to prevent the lubricating oil from flowing out from the container. 
     According to a third aspect of the invention, in the electric compressor of the first aspect, the division wall and the container are integrally formed together. With this aspect, the structure is simplified, and the cost can be reduced. 
     According to a fourth aspect of the invention, in the electric compressor of the first aspect, the drive shaft is used in a horizontal direction, and the connection space and the wire passage are formed at positions higher than an oil level of lubricating oil stored in the container. With this aspect, it is possible to prevent lubricating oil from flowing into the connection between the sealed terminal and the lead wire, and to prevent the insulation resistance from being lowered. 
     According to a fifth aspect of the invention, in the electric compressor of the fourth aspect, the connection space and the wire passage are formed at positions higher than rotation centers of the motor and the compressing mechanism. With this aspect, especially when the compressor is operated at low speed at which the lubricating oil is prone to stay, the oil level does not reach the wire passage and the connection space. With this structure, deterioration in reliability of the electric compressor caused by deterioration of insulation resistance can be prevented. 
     According to a sixth aspect of the invention, in the electric compressor of the fourth aspect, the division wall is inclined, and the wire passage is formed at position lower than the sealed terminal. With this aspect, even when lubricating oil in a mist-state enters the connection space, the lubricating oil flows out from the wire passage and thus, the lubricating oil does not stay in the connection space. With this, the deterioration of the insulation resistance can be prevented. 
     A seventh aspect of the invention provides an electric compressor in which a motor and a compressing mechanism are accommodated in a container, the compressing mechanism is connected to the motor through a drive shaft, the container is divided into a first space and a second space by the compressing mechanism, the motor is disposed in the first space, a discharge port which is in communication with the first space is formed and, a communication passage for bringing the first space and a discharge chamber into communication with each other is formed in an outer periphery of the compressing mechanism, wherein the second space is divided into the discharge chamber and a connection space by a division wall, a discharge hole of the compressing mechanism is in communication with the discharge chamber, a sealed terminal is disposed in the connection space, a wire passage for bringing the first space and the connection space into communication with each other is formed in an outer periphery of the compressing mechanism, and a lead wire for connecting the motor and the sealed terminal with each other is disposed in the wire passage. With this aspect, the wire passage of the compressing mechanism through which the lead wire is passed is separated from the communication passage for refrigerant, vibration of the lead wire caused by gas pulse can be suppressed, the lead wire is prevented from being damaged, and the reliability of the electric compressor can be enhanced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of an electric compressor of a first embodiment of the present invention; 
         FIG. 2  is a side view of the electric compressor shown in  FIG. 1 ; 
         FIG. 3  is a sectional view of a conventional vertical type electric compressor; and 
         FIG. 4  is a plan view of the electric compressor shown in  FIG. 3 . 
     
    
    
     PREFERRED EMBODIMENT OF THE INVENTION 
     An embodiment of the present invention will be explained with reference to  FIGS. 1 and 2 . The invention is not limited to the embodiment. 
       FIG. 1  is a sectional view of an electric compressor of a first embodiment of the present invention.  FIG. 2  is a side view of the electric compressor shown in  FIG. 1 . 
     The electric compressor of the embodiment shown in  FIGS. 1 and 2  will be explained below. 
     The electric compressor  1  includes a container comprising a main container  3  and an auxiliary container  80 , a compressing mechanism  4  which sucks, compresses and discharges working fluid, a motor  5  which drives a compressing mechanism  4 , a liquid reservoir  6  accommodating therein lubricating oil  7  for lubricating sliding portions including the compressing mechanism  4 , an oil supply device  19  and a sealed terminal  90 . 
     The compressing mechanism  4  and the motor  5  are accommodated in the container. The compressing mechanism  4  and the motor  5  are connected to each other through a drive shaft  14 . The container is divided into a first space and a second space by the compressing mechanism  4 . The motor  5  is disposed in the first space. 
     The second space is located in the compressing mechanism  4  on the opposite side from the motor  5 . The second space is divided into a discharge chamber  62  and a connection space  65  by a division wall  80   b  which is integrally formed with the auxiliary container  80 . A discharge hole  31  of the compressing mechanism  4  is in communication with the discharge chamber  62 , and the sealed terminal  90  is disposed in the connection space  65 . A wire passage  63  which brings the first space and the connection space  65  into communication with each other is formed in an outer periphery of the compressing mechanism  4 . A lead wire  5   c  which connects the motor  5  and the sealed terminal  90  with each other is formed in a wire passage  64 . 
     That is, in this embodiment, the second space is located in the compressing mechanism  4  on the opposite side from the motor  5 , and is occupied by discharged gas. The second space is divided by the division wall  80   b  into the discharge chamber  62  and the connection space  65  in which the sealed terminal  90  and the lead wire  5   c  are connected to each other. 
     The main container  3  is formed with a discharge port  9  which is in communication with the first space. A communication passage  63  which brings the first space and the discharge chamber  62  into communication with each other is formed in an outer periphery of the compressing mechanism  4 . 
     In the embodiment, as the electric compressor  1 , a horizontal type compressor which is set up horizontally using mounting legs  2  located around a body of the electric compressor  1  is used. A scroll type compressing mechanism is used as the compressing mechanism  4 . The motor  5  is driven by a motor drive circuit (not shown). Working fluid which is used in the embodiment is a refrigerant. Lubricating oil  7  is used for lubricating sliding portions and for sealing the sliding portions of the compressing mechanism  4 . The lubricating oil  7  has compatibleness with respect to the refrigerant. 
     A positive-displacement pump  13 , an auxiliary bearing  41 , the motor  5  and a main bearing member  51  having a main bearing  42  are disposed in the main container  3  from the side of one end wall  3   a  in the axial direction. 
     A lid body  52  is fitted to the positive-displacement pump  13  from an outer surface of the end wall  3   a . A pump chamber  53  is formed between the lid body  52  and the end wall  3   a . The pump chamber  53  is in communication with the liquid reservoir  6  through a suction passage  54 . 
     The auxiliary bearing  41  is supported by the end wall  3   a . The end wall  3   a  is pivotally supports the drive shaft  14  on a side connected to the positive-displacement pump  13  through the auxiliary bearing  41 . 
     The motor  5  rotates the drive shaft  14  by a stator  5   a  which is fixed to an inner periphery of the main container  3  by shrink fit and by a rotor  5   b  fixed to the drive shaft  14 . 
     An eccentric shaft  14   a  is integrally formed on an end surface of the drive shaft  14  on the side of the compressing mechanism  4 . A bush  30  is fitted over the eccentric shaft  14   a . The bush  30  makes it possible to smoothly turn an orbiting scroll  12  which is opposed to a fixed scroll  11  through an eccentric bearing  43 . 
     A cylindrical portion  12   b  projects from a back surface of an orbiting scroll end plate  12   a  of the orbiting scroll  12 . An eccentric bearing  43  is accommodated in the cylindrical portion  12   b . In inner ring of the eccentric bearing  43  is fitted over the bush  30 , and an outer ring of the eccentric bearing  43  is fitted to into the cylindrical portion  12   b.    
     The fixed scroll  11  is provided with a suction hole (not shown). A valve device (not shown) is provided for interrupting the communication between the suction hole and the back pressure chamber  20 . 
     The main bearing member  51  is fixed to an inner periphery of the auxiliary container  80  through a bolt (not shown) or the like, and the main bearing member  51  pivotally supports the drive shaft  14  on the side of the compressing mechanism  4  through the main bearing  42 . An outer peripheral surface of the fixed scroll  11  is mounted on an outer peripheral surface of the main bearing member  51 , the orbiting scroll  12  is sandwiched between the main bearing member  51  and the fixed scroll  11 , and an Oldham ring  26  which prevents the orbiting scroll  12  from rotating and turns the orbiting scroll  12  is provided between the main bearing member  51  and the orbiting scroll  12 . With this, the compressing mechanism  4  is configured. 
     A portion (e.g., the main bearing member  51 ) of the compressing mechanism  4  which protrudes and is exposed from the auxiliary container  80  is covered with the main container  3  by fixing the main container  3  and the auxiliary container  80  to each other through a bolt  18  such that openings of the main container  3  and the auxiliary container  80  butts against each other. With this, the end wall  3   a  of the main container  3  is formed on the auxiliary container  80  on the opposite side from an end wall  80   a  in the axial direction. 
     The compressing mechanism  4  is located between a suction port  8  provided in the auxiliary container  80  and a discharge port  9  formed in the main container  3 . A suction hole (not shown) formed in the fixed scroll  11  of the compressing mechanism  4  is in direct communication with the suction port  8 . 
     The discharge hole  31  is opened at the discharge chamber  62  formed in the auxiliary container  80  through a reed valve  32 . 
     The discharge chamber  62  is in communication with the first space located between the compressing mechanism  4  and the end wall  3   a , that is, located on the side of the motor  5  which is in communication with the discharge port  9 , through the communication passage  63  formed between the main container  3  and the fixed scroll  11 , and between the main container  3  and the main bearing member  51 . The communication passage  63  may be formed so as to penetrate through the fixed scroll  11  and the main bearing member  51 . 
     The lead wire  5   c  of the motor  5  is led out through the wire passage  64  formed between the main container  3  and the fixed scroll  11 , and between the main container  3  and the main bearing member  51 . The lead wire  5   c  is connected to the sealed terminal  90  which penetrates the auxiliary container  80 . The sealed terminal  90  is connected to a drive circuit. The wire passage  64  may be formed so as to penetrate through the fixed scroll  11  and the main bearing member  51 . 
     Next, the operation of the electric compressor of the embodiment will be explained. 
     When the orbiting scroll  12  is turned with respect to the fixed scroll  11  by the drive shaft  14  of the motor  5 , a compression space  10  formed by meshing the fixed scroll  11  and the orbiting scroll  12  of the compressing mechanism  4  with each other is varied in capacity and moved. With this capacity variation, refrigerant returning from an external cycle is introduced into the suction hole of the fixed scroll  11  from the suction port  8  of the auxiliary container  80 , and is sucked into the compression space  10 . The sucked refrigerant is compressed in the compression space  10  and is discharged into the discharge chamber  62  from the discharge hole  31 . 
     Refrigerant discharged into the discharge chamber  62  enters the first space on the side of the motor  5  from the second space on the opposite side from the motor  5  through the communication passage  63 , the refrigerant cools the motor  5  and flows out into the external cycle through the discharge port  9  of the main container  3 . In the suction, compression and discharge processes, the refrigerant separates the lubricating oil  7  by gas/liquid separation effect of collision or choke, and a portion of the lubricating oil  7  attached to the refrigerant lubricates the auxiliary bearing  41 . 
     On the other hand, lubricating oil  7  stored in the liquid reservoir  6  of the main container  3  is supplied by the positive-displacement pump  13  driven by the drive shaft  14  to a liquid reservoir  21  formed in a back surface of the orbiting scroll  12  through an oil supply passage  15  of the drive shaft  14 . The lubricating oil  7  can be supplied utilizing a pressure difference in the main container  3 . 
     A portion of the lubricating oil  7  supplied to the liquid reservoir  21  passes through the back surface of the orbiting scroll end plate  12   a , is limited to a predetermined pressure by a drawing  23  (pressure reducing means), and is supplied to the back pressure chamber  20  located on a surface opposite from a lap of the outer periphery of the orbiting scroll  12 . The back pressure in the back pressure chamber  20  is adjusted to a predetermined value by a valve device provided in the fixed scroll  11 , the orbiting scroll  12  is pressed by this predetermined pressure, and the lubricating oil  7  is led to the compression space  10 , thereby sealing and lubricating between the fixed scroll  11  and the orbiting scroll  12 . 
     The lubricating oil  7  is supplied to a tip end of a scroll lap of the orbiting scroll  12  through the interior of the orbiting scroll  12 . That is, the lubricating oil  7  is supplied to a holding groove  25  which holds a chip seal  24  which seals between the fixed scroll  11  and the orbiting scroll  12 , thereby sealing and lubricating between the fixed scroll  11  and the orbiting scroll  12 . 
     Another portion of the lubricating oil  7  supplied to the liquid reservoir  21  lubricates the main bearing  42  and the eccentric bearing  43  through the eccentric bearing  43 , the liquid reservoir  22  and the main bearing  42 , and then, the lubricating oil  7  flows out into the first space on the side of the motor  5  and is collected into the liquid reservoir  6 . 
     According to the configuration, the electric compressor of the embodiment can prevent gas discharged from the compressing mechanism  4  from directly flowing into the connection space  65  connecting the sealed terminal  90  and the lead wire  5   c  of the motor  5 . That is, the discharged gas fills the wire passage  64  through which the lead wire  5   c  is passed, but does not flow into the wire passage  64 . 
     In other words, the wire passage  64  of the compressing mechanism  4  through which the lead wire  5   c  passes can be separated from the refrigerant communication passage  63 . 
     With the above effect, vibration of lead wire  5   c  caused by gas pulse can be suppressed, the lead wire can be prevented from being damaged and the reliability can be enhanced. 
     As a result, it is possible to eliminate unnecessary expensive operations such as operation for protecting the lead wire  5   c  using a tube, operation for fixing the lead wire  5   c , and operation for cutting the casting surface of the wire passage  64  to enhance the surface roughness. 
     According to the electric compressor of the embodiment, the discharge port  9  which is in communication with the first space is formed, and a communication passage  63  which brings the first space and the discharge chamber  62  into communication with each other is formed in the outer periphery of the compressing mechanism  4 . With this configuration, refrigerant discharged into the discharge chamber  62  can be introduced to the peripheries of the motor  5  by the communication passage  63 , and is allowed to flow out from the main container  3  through the discharge port  9 . Therefore, the lubricating oil  7  can be separated from the refrigerant so that the lubricating oil  7  is prevented from flowing out from the main container  3 . 
     According to the electric compressor of the embodiment, since the division wall  80   b  and the auxiliary container  80  are integrally formed together, the structure is simple, and the cost of the electric compressor can be reduced. 
     According to the electric compressor of the embodiment in which the drive shaft  14  is used in the horizontal direction, the connection space  65  and the wire passage  64  are formed higher than the oil level of the lubricating oil  7  stored in the main container  3 . With this structure, it is possible to prevent the lubricating oil  7  from flowing into the connection space  65  connecting the sealed terminal  90  and the lead wire  5   c , and to prevent the insulation resistance from being deteriorated by the lubricating oil  7 . 
     According to the electric compressor of the embodiment, as shown in  FIG. 2 , the connection space  65  and the wire passage  64  are formed above the oil level of the lubricating oil  7 , and are formed above the rotation centers of the motor  5  and the compressing mechanism  4 . With this configuration, especially when the compressor is operated at low speed at which the lubricating oil  7  is prone to stay, even though the oil level rises and the lubricating oil  7  is stirred by the rotor  5   b  of the motor  5 , the lubricating oil  7  does not reach the wire passage  64  and the connection space  65 . With this structure, deterioration in reliability of the electric compressor caused by deterioration of insulation resistance can be prevented. 
     According to the electric compressor of the embodiment, as shown in  FIG. 2 , the division wall  80   b  is inclined in the horizontal direction or downward toward the outer periphery, and the wire passage  64  is formed at a position including the lowermost portion of the connection space  65 , e.g., at a location lower than the sealed terminal  90 . With this configuration, even though lubricating oil  7  in a mist-state enters the connection space  65 , the lubricating oil  7  flows out from the inclined wire passage  64  and thus, the lubricating oil  7  does not stay in the connection space  65 . With this, the deterioration of the insulation resistance caused by the lubricating oil  7  can be prevented, and it is possible to provide a reliable electric compressor. 
     The electric compressor of the present invention can prevent a lead wire of a motor from being damaged, can enhance the reliability, and can be applied to an electric compressor which accommodates a compressing mechanism which sucks, compresses and discharges fluid, and the motor which drives the compressing mechanism in a container, and in which the motor is driven by a motor drive circuit.