JP2008008269A - Reciprocating compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reciprocating compressor capable of reducing vibration, weight and size. <P>SOLUTION: At an axially middle part of a crank shaft 3, two eccentric shaft parts 3A, 3B are provided so as to be positioned a predetermined dimension apart radially from an axis line 01-01 as a rotation center. At the eccentric shaft parts 3A, 3B, pistons 10, 15, 20, 25 are connected via connection rods 12, 17, 22, 27. A hollow part 4 positioned in the eccentric shaft part 3A is provided for the crank shaft 3. Thus, a center of gravity of the crank shaft 3 can be positioned at a radially opposite side of the eccentric shaft part 3A across the axis 01-01. Hence, inertial couple F3 is canceled by a centrifugal force F4 of the crank shaft 3 and vibration can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reciprocating compressor suitable for use, for example, for compressing air, refrigerant and the like.

  In general, a reciprocating compressor has a crankshaft that is rotationally driven by a drive source, a cylinder on which a cylinder head having a suction port and a discharge port is mounted, and suction from the suction port by reciprocating in the cylinder. It is set as the structure provided with the piston which compresses gas and discharges compressed gas from a discharge port, and the connecting rod which connects this piston and a crankshaft (for example, refer patent document 1).

  The reciprocating compressor rotates and drives the eccentric crankshaft using a drive source such as an electric motor. At this time, the piston connected to the crankshaft via the connecting rod reciprocates in the cylinder. Thus, the reciprocating compressor is configured to compress the gas sucked from the suction port in the cylinder and discharge the compressed gas from the discharge port.

JP 2005-315251 A

  By the way, in the above-described reciprocating compressor according to the prior art, the centrifugal force of the piston or the like and the reciprocating inertial force act as the crankshaft rotates, and the entire compressor vibrates. Therefore, a balance weight is added to the crankshaft in order to cancel the centrifugal force of the piston and the reciprocating inertial force. As a result, the conventional reciprocating compressor has a problem that the weight of the crankshaft increases and the size thereof increases.

  Further, when a reciprocating inertial force such as a piston acts on the crankshaft, the crankshaft may be deformed. For this reason, in order to increase the strength of the crankshaft, it is necessary to increase the diameter of the crankshaft or to increase the number of locations for rotating and supporting the crankshaft in order to compensate for the lack of strength of the crankshaft. However, when the diameter of the crankshaft is increased, the weight of the crankshaft further increases. In addition, when the crankshaft is rotationally supported at many locations, the structure for rotationally supporting the crankshaft is complicated, and there are problems that the number of components such as a bearing for rotational support increases and the manufacturing cost increases. .

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a reciprocating compressor capable of reducing vibration and reducing the weight and size.

  In order to solve the above-described problems, the invention of claim 1 is directed to a crankshaft that is rotationally driven by a drive source, a cylinder on which a cylinder head having a suction port and a discharge port is mounted, and reciprocating motion in the cylinder. In the reciprocating compressor comprising: a piston that compresses the gas sucked from the suction port and discharges the compressed gas from the discharge port; and a connecting rod that connects the piston and the crankshaft. Is characterized in that a hollow part, which is partially hollow, is provided to suppress vibration during rotation of the crankshaft.

  According to a second aspect of the present invention, there is provided a crankshaft that is rotationally driven by a drive source, a cylinder on which a cylinder head having a suction port and a discharge port is mounted, and a reciprocating motion in the cylinder so as to move from the suction port. In a reciprocating compressor comprising a piston that compresses sucked gas and discharges compressed gas from a discharge port, and a connecting rod that connects the piston and the crankshaft, a part of the crankshaft is included in the reciprocating compressor. Different density portions having different densities are provided to suppress vibration during rotation of the crankshaft.

  According to a third aspect of the present invention, the crankshaft is configured to be provided with support portions for rotationally supporting both ends thereof.

  According to the first aspect of the present invention, the crankshaft is provided with a hollow portion that is partially hollow, so that the weight balance of the crankshaft can be displaced from the center of rotation by the hollow portion. At this time, the hollow portion is disposed at a position on the crankshaft opposite to the position where the balance weight is provided in the related art with respect to the rotation center. As a result, the center of gravity of the crankshaft can be arranged at a position that is substantially the same as when the balance weight is provided, so that vibrations caused by the centrifugal force of the piston and the reciprocating inertial force act on the crankshaft. It can be canceled out by centrifugal force, and vibration of the entire compressor can be suppressed.

  Further, since the hollow portion is provided in the crankshaft instead of the balance weight, the crankshaft can be reduced in size and weight. Further, since the vibration is suppressed by providing a hollow portion on the crankshaft, the crankshaft may be supported by rotation as in the case of providing a balance weight as in the prior art, and a support portion for rotatingly supporting the crankshaft. There is no need to increase. For this reason, the support structure of a crankshaft can be simplified and manufacturing cost can be suppressed.

  According to the second aspect of the present invention, since the crankshaft is provided with the different density portion, part of which has a different density, the weight balance of the crankshaft can be displaced from the center of rotation by the different density portion. At this time, for example, the density of the different density portion is made lower than that of the crankshaft, and the crankshaft is arranged at a position opposite to the position where the balance weight is provided in the related art with respect to the rotation center. As a result, the center of gravity of the crankshaft can be arranged at a position that is substantially the same as when the balance weight is provided, so that vibrations caused by the centrifugal force of the piston and the reciprocating inertial force act on the crankshaft. It can be canceled out by centrifugal force, and vibration of the entire compressor can be suppressed.

  The different density portion may be formed by providing a hole in the crankshaft and enclosing a member having a density different from that of the crankshaft in the hole. In this case, the position of the center of gravity of the crankshaft can be adjusted by adjusting the density and amount of the members sealed in the holes. For this reason, after assembling the compressor, the center of gravity of the crankshaft can be adjusted while confirming the actual vibration state of the compressor.

  Further, since the crankshaft is provided with the different density portion instead of the balance weight, the crankshaft can be reduced in size and weight. Furthermore, since vibrations are suppressed by providing different density portions on the crankshaft, the crankshaft may be supported by rotation as in the case of providing a balance weight as in the prior art, and support for rotating support of the crankshaft. There is no need to increase the number of parts. For this reason, the support structure of a crankshaft can be simplified and manufacturing cost can be suppressed.

  According to the invention of claim 3, since the support portions for rotating and supporting are provided at both ends of the crankshaft, only two support portions are provided even when a plurality of pistons are coupled to the crankshaft. The crankshaft can be supported by rotation. For this reason, the support structure of a crankshaft can be simplified and manufacturing cost can be reduced.

  Hereinafter, a horizontally opposed four-cylinder air compressor will be described as an example of a reciprocating compressor according to an embodiment of the present invention, and will be described in detail with reference to the accompanying drawings.

  First, FIGS. 1 to 3 show a first embodiment of the present invention. In the figure, reference numeral 1 denotes a horizontally opposed four-cylinder type air compressor as a reciprocating compressor. The air compressor 1 is composed of a left cylinder 8, 18 and a right cylinder 13, 23 which will be described later. It is arranged at a horizontally opposed position that faces in the horizontal direction across the case 2.

  Reference numeral 2 denotes a crankcase of the air compressor 1, and the crankcase 2 is formed, for example, as a hollow rectangular metal case. That is, the crankcase 2 includes front and rear wall surfaces 2A and 2B that are spaced apart in the front and rear directions (length direction) so as to face each other in the axial direction of the crankshaft 3 described later, and the crankshaft 3 Is provided between the wall surfaces 2A and 2B so as to be sandwiched from above and below, and between the wall surfaces 2A and 2B so that the crankshaft 3 is sandwiched from the left and right sides. The outer shape is constituted by the left and right wall surfaces 2E and 2F provided over the entire surface.

  Here, inside the front wall surface 2A, a bottomed bearing boss portion 2G is provided substantially at the center, and the rear wall surface 2B passes through a position coaxial with the bearing boss portion 2G. A bearing boss 2H is provided. Further, the left and right wall surfaces 2E and 2F are provided with two insertion holes 2J through which connecting rods 12, 17, 22, and 27, which will be described later, are inserted so as to be able to swing, at intervals in the front and rear directions. .

  Reference numeral 3 denotes a crankshaft rotatably attached to the crankcase 2. The crankshaft 3 has axially opposite sides on the front wall surface 2A and the rear wall surface 2B of the crankcase 2 via main bearings 6 and 7, which will be described later. It is supported. As a result, the crankshaft 3 can rotate around the axis O1-O1. Further, for example, two eccentric shaft portions 3A and 3B are provided at the axial intermediate portion of the crankshaft 3 so as to be separated from the axis O1-O1 serving as the rotation center by a predetermined dimension in the radial direction. The eccentric shaft portions 3A and 3B are eccentric to the opposite sides in the diametrical direction with respect to the axis O1-O1. Further, one end of the crankshaft 3 protrudes outward from the rear wall surface 2B of the crankcase 2 to form a protruding end 3C.

  A hollow portion 4 is provided in the crankshaft 3, and the hollow portion 4 extends from the other end portion of the crankshaft 3 by bending along the length direction of the crankshaft 3. Moreover, the hollow part 4 is provided in the inside of eccentric shaft part 3A among two eccentric shaft parts 3A and 3B, for example. As a result, the hollow portion 4 is disposed on the opposite side of the hollow portion 4 with the center of gravity of the crankshaft 3 sandwiching the axis O1-O1 serving as the rotation center. As a result, the position of the center of gravity of the crankshaft 3 is arranged at substantially the same position as when a balance weight according to the prior art is provided, as will be described later.

  A pulley 5 is attached to the protruding end 3C of the crankshaft 3. The pulley 5 is connected to a drive source (not shown) such as a motor via a belt or the like. The pulley 5 rotates the crankshaft 3 together with the drive source. A cooling fan 5 </ b> A that supplies cooling air toward the compressor 1 is formed on the inner peripheral side of the pulley 5.

  Reference numerals 6 and 7 denote main bearings as support parts inserted into the bearing boss parts 2G and 2H of the crankcase 2, respectively. These main bearings 6 and 7 are formed as ball bearings or the like, for example, and include eccentric shaft parts 3A, 3A, The crankshaft 3 is disposed on both ends in the axial direction with 3B interposed therebetween. The main bearings 6 and 7 support the crankshaft 3 in the crankcase 2 so as to be rotatable.

  Next, the four cylinders 8, 13, 18, and 23 constituting the compression unit that performs the air compression operation will be described. Out of the four cylinders 8, 13, 18, 23, the left front cylinder 8 and the right front cylinder 13 located on the front side make a pair, opposed to each other in the horizontal direction with an opening angle of about 180 °, and the left rear cylinder located on the rear side. The cylinder 18 and the right rear cylinder 23 are paired and opposed in the horizontal direction with an opening angle of approximately 180 °.

  First, reference numeral 8 denotes a left front cylinder provided near the front side of the left wall surface 2E of the crankcase 2. The cylinder 8 compresses and discharges the sucked air, and is roughly constituted by a cylinder 9, a piston 10, a connecting rod 12, and the like which will be described later.

  Reference numeral 9 denotes a left front cylinder constituting the left front cylinder 8. The cylinder 9 is erected on the left wall surface 2E of the crankcase 2 so as to correspond to the left front insertion hole 2J.

  A piston 10 is fitted in the cylinder 9 so as to be able to reciprocate. The piston 10 is connected to a crankshaft 3 via a connecting rod 12 which will be described later. To reciprocate.

  Reference numeral 11 denotes a cylinder head provided on the tip side of the cylinder 9, and the cylinder head 11 is formed with a suction port 11A and a discharge port 11B. In addition, the cylinder head 11 is provided with a suction valve 11C that opens when the outside air is sucked and a discharge valve 11D that opens when the compressed air is discharged.

  A connecting rod 12 connects the crankshaft 3 and the piston 10, and the connecting rod 12 converts the rotation of the crankshaft 3 into a reciprocating motion of the piston 10. Here, the large end portion 12A located on the proximal end side of the connecting rod 12 is rotatably attached to the eccentric shaft portion 3A via a large end bearing 12C made of, for example, a ball bearing. Further, the small end portion 12B positioned on the distal end side of the connecting rod 12 is swingably attached to the piston 10 via a small end portion bearing 12D made of, for example, a sleeve bearing and a piston pin 12E.

  When the crankshaft 3 is rotationally driven and the piston 10 enters the suction stroke, the left front cylinder 8 opens the suction valve 11C of the cylinder head 11 and sucks outside air into the cylinder 9 through the suction port 11A. . Further, in the compression stroke, the suction valve 11C is closed to compress the air in the cylinder 9, and the discharge valve 11D is opened near the top dead center, whereby the compressed air in the cylinder 9 is discharged to the discharge port 11B. And discharged toward an external air tank (not shown) or the like.

  Next, reference numeral 13 denotes a front right cylinder provided on the front side of the right wall surface 2F of the crankcase 2 so as to face the front left cylinder 8. This cylinder 13 is roughly constituted by a cylinder 14, a piston 15, a cylinder head 16, a connecting rod 17, and the like, similar to the left front cylinder 8. The connecting rod 17 connects the eccentric shaft portion 3 </ b> A of the crankshaft 3 and the piston 15. Here, since the right front cylinder 13 has substantially the same configuration as the left front cylinder 8, the detailed configuration is denoted by the reference numerals corresponding to the cylinder 8 and description thereof is omitted.

  Reference numeral 18 denotes a left rear cylinder provided on the rear side of the left wall surface 2E of the crankcase 2 so as to be located on the rear side of the left front cylinder 8. The cylinder 18 is roughly configured by a cylinder 19, a piston 20, a cylinder head 21, a connecting rod 22, and the like, almost like the left front cylinder 8. The connecting rod 22 connects the eccentric shaft portion 3 </ b> B of the crankshaft 3 and the piston 20. Here, since the left rear cylinder 18 has substantially the same configuration as the left front cylinder 8, the detailed configuration will be denoted by the reference numerals corresponding to the cylinder 8 and description thereof will be omitted.

  Further, reference numeral 23 denotes a right rear cylinder provided on the rear side of the right wall surface 2F of the crankcase 2 so as to face the left rear cylinder 18. The cylinder 23 is roughly composed of a cylinder 24, a piston 25, a cylinder head 26, a connecting rod 27, and the like, similar to the left front cylinder 8. The connecting rod 27 connects the eccentric shaft portion 3 </ b> B of the crankshaft 3 and the piston 25. Here, since the right rear cylinder 23 has substantially the same configuration as the left front cylinder 8, the detailed configuration is denoted by the reference numerals corresponding to the cylinder 8 and the description thereof is omitted.

  The four cylinders 8, 13, 18, and 23 have a phase difference of 180 ° between the piston 10 of the left front cylinder 8 and the piston 15 of the right front cylinder 13 that form a pair as the crankshaft 3 rotates. Reciprocates. On the other hand, the piston 20 of the left rear cylinder 18 and the piston 25 of the right rear cylinder 23 reciprocate with a phase difference of 180 °. At this time, the front cylinders 8 and 13 and the rear cylinders 18 and 23 reciprocate in opposite phases, so that the air compressor 1 reciprocates the pistons 10, 15, 20, and 25. The inertial force (moment of inertia) generated by the above can be canceled in a well-balanced manner, and vibration, noise, and the like can be reduced.

  The air compressor 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the crankshaft 3 is rotationally driven by a drive source such as a motor, in the cylinders 8, 13, 18, and 23, for example, in the cylinder 8, the rotation of the crankshaft 3 is converted into the reciprocating motion of the piston 10 by the connecting rod 12. The piston 10 is reciprocated in the cylinder 9.

  Thereby, in the suction stroke of the piston 10, the suction valve 11 </ b> C is opened to suck the outside air into the cylinder 9. Further, in the compression stroke, the suction valve 11C is closed to compress the air in the cylinder 9, and the discharge valve 11D is opened in the vicinity of the top dead center. It discharges toward (not shown) etc. Since this operation is the same for the other cylinders 13, 18, and 23, the description thereof will be omitted.

  Next, the vibration suppressing action of the air compressor 1 according to this embodiment will be described with reference to FIGS.

  First, considering the comparative example shown in FIG. 4, this comparative example shows a case where a balance weight 32 is provided on a solid crankshaft 31 in the same manner as in the prior art in order to suppress vibration. Here, for example, two eccentric shaft portions 31A and 31B are provided in the axial direction intermediate portion of the crankshaft 31 in substantially the same manner as the crankshaft 3 according to the present embodiment, and these eccentric shaft portions 31A and 31B are , They are eccentric to the opposite sides in the diametrical direction with respect to the axis O1-O1.

  At this time, the pistons 10, 15, 20, and 25 are connected to the eccentric shaft portions 31A and 31B of the crankshaft 31 via the connecting rods 12, 17, 22, and 27, respectively. For this reason, as the pistons 10, 15, 20, 25 reciprocate, reciprocating inertia forces F1, F2 directed radially outwardly act on the eccentric shaft portions 31A, 31B, respectively. Here, the reciprocating inertia forces F1 and F2 are opposite to each other across the axis O1-O1. Thereby, the inertia couple F3 which rotates centering on the rotation reference point P used as the intermediate point of eccentric shaft part 31A, 31B acts on the crankshaft 31, for example.

  On the other hand, the balance weight 32 is disposed between the eccentric shaft portions 31A and 31B of the crankshaft 31, for example. Further, the center of gravity of the balance weight 32 is disposed on the eccentric shaft portion 31A side with respect to the axial direction of the crankshaft 31 from the rotation reference point P, and the axis O1-O1 is sandwiched with respect to the radial direction of the crankshaft 31. And is arranged on the side opposite to the eccentric shaft portion 31A.

  As a result, centrifugal force F4 acts on the balance weight 32 as the crankshaft 31 rotates, and this centrifugal force F4 acts in a direction to cancel the reciprocating inertial force F1 of the eccentric shaft portion 31A. For this reason, in the comparative example, the inertia couple F3 generated in the crankshaft 31 is reduced by the centrifugal force F4 of the balance weight 32.

  On the other hand, in the present embodiment, as shown in FIG. 3, the hollow portion 4 is provided in the crankshaft 3 instead of the balance weight 32 according to the comparative example. At this time, the hollow portion 4 is located in the eccentric shaft portion 3A of the crankshaft 3 as a position opposite to the position where the balance weight 32 of the comparative example is provided across the axis O1-O1 in the radial direction. Is provided. As a result, the center of gravity of the crankshaft 3 can be disposed on the opposite side of the eccentric shaft portion 3A across the axis O1-O1 with respect to the radial direction. The crankshaft 31 can be disposed at substantially the same position. As a result, although the inertia couple F3 due to the reciprocating inertia forces F1 and F2 also acts on the crankshaft 3, the inertia couple F3 can be canceled by the centrifugal force F4 acting on the crankshaft 3, and the compressor 1 as a whole. Can be suppressed.

  Thus, according to the present embodiment, the crankshaft 3 is provided with the hollow portion 4 that is partially hollow, so that the weight balance of the crankshaft 3 is displaced from the axis O1-O1 by the hollow portion 4. be able to. As a result, the centrifugal force F4 of the crankshaft 3 can be generated in the direction to cancel the inertia couple F3 due to the reciprocating inertia forces F1, F2 of the pistons 10, 15, 20, 25, etc. Can be suppressed.

  Further, since vibration is suppressed by providing the hollow portion 4 in the crankshaft 3, there is no need to provide a balance weight as in the prior art, and the crankshaft 3 can be reduced in size and weight. Furthermore, since the inertia couple F3 due to the reciprocating inertia forces F1 and F2 is canceled by providing a hollow portion in the crankshaft 3, the crankshaft 3 is provided at both ends as in the case of providing a balance weight as in the prior art. What is necessary is just to carry out rotation support in two places, and it is not necessary to increase the support part (main bearing) for carrying out rotation support of the crankshaft 3. FIG.

  For this reason, the crankshaft 3 may be rotationally supported by the two main bearings 6 and 7 provided at both ends thereof. As a result, even when a plurality of (for example, four) pistons 10, 15, 20, 25 are connected to the crankshaft 3, the two pistons 10, 15, 20, 25 are positioned on both ends in the axial direction across the pistons 10, 15, 20, 25. The crankshaft 3 can be rotationally supported only by the main bearings 6 and 7. As a result, the support structure of the crankshaft 3 can be simplified and the manufacturing cost can be reduced.

  Next, FIG. 5 shows a second embodiment of the present invention. The feature of the present embodiment is that the crankshaft is provided with a low density portion, a part of which has a low density. is there. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  Reference numeral 41 denotes a crankshaft according to the present embodiment. The crankshaft 41 is formed by using, for example, a metal material, and substantially the same as the crankshaft 3 according to the first embodiment, both ends thereof are main bearings (not shown). ) To be rotatably supported. As a result, the crankshaft 41 can rotate around the axis O1-O1. Further, for example, two eccentric shaft portions 41A and 41B are provided in the axial direction intermediate portion of the crankshaft 41 so as to be separated from the axis O1-O1 serving as the rotation center by a predetermined dimension in the radial direction. The eccentric shaft portions 41A and 41B are eccentric to the opposite sides in the diametric direction with respect to the axis O1-O1. One end of the crankshaft 41 serves as a projecting end 41C, and the projecting end 41C is connected to a drive source (both not shown) via a pulley.

  Reference numeral 42 denotes a low density portion as a different density portion provided on the crankshaft 41. The low density portion 42 is substantially the same as the hollow portion 4 according to the first embodiment from the other end portion of the crankshaft 41. The hollow portion 42A is bent and extended along the length direction of the crankshaft 41, and the sealing member 42B is sealed in the hollow portion 42A. At this time, the enclosing member 42 </ b> B is formed of a resin material or a resin material mixed with a metal or the like as a material having a lower density than the crankshaft 41.

  Moreover, the low density part 42 is provided in the inside of eccentric shaft part 41A among the eccentric shaft parts 41A and 41B of two places, for example. Thereby, the low density part 42 is arrange | positioned on the opposite side of the low density part 42 on both sides of axis line O1-O1 used as the rotation center about the gravity center position of the crankshaft 41. FIG. As a result, the position of the center of gravity of the crankshaft 41 is arranged at substantially the same position as when the balance weight according to the prior art is provided.

  Thus, also in this embodiment, it is possible to obtain substantially the same operational effects as those in the first embodiment. In particular, in the present embodiment, since the crankshaft 41 is provided with the low density portion 42, the weight balance of the crankshaft 41 can be displaced from the axis O1-O1 by the low density portion 42. As a result, as in the first embodiment, the centrifugal force F4 of the crankshaft 41 is set in the direction to cancel the inertia couple F3 due to the reciprocating inertia forces F1, F2 of the pistons 10, 15, 20, 25, etc. The vibration of the compressor 1 whole can be suppressed.

  Further, since the low density portion 42 is configured by sealing the sealing member 42B in the hollow portion 42A provided in the crankshaft 41, the center of gravity position of the crankshaft 41 is adjusted by adjusting the density and amount of the sealing member 42B. Can be adjusted. For this reason, after the compressor 1 is assembled, the center of gravity of the crankshaft 41 can be adjusted while confirming the actual vibration state of the compressor 1.

  Further, since the crankshaft 41 is provided with the low density portion 42 instead of the balance weight, the crankshaft 41 can be reduced in size and weight. Furthermore, since the vibration is suppressed by providing the low-density portion 42 on the crankshaft 41, the crankshaft 41 can be rotated and supported at two locations on both ends thereof as in the case of providing a balance weight as in the prior art. Well, it is not necessary to increase the support for rotating and supporting the crankshaft 41. For this reason, the support structure of the crankshaft 41 can be simplified, and the manufacturing cost can be suppressed.

  In the present embodiment, the crankshaft 41 is provided with a low density portion 42 having a lower density than the crankshaft 41. However, the present invention is not limited to this. For example, as in the first modification shown in FIG. 6, the crankshaft 41 may be provided with a high-density portion 43 having a higher density than the crankshaft 41. In this case, the high density portion 43 is positioned between the eccentric shaft portions 41A and 41B of the crankshaft 41, for example, on the opposite side of the eccentric shaft portion 41A from the axis O1-O1 with respect to the radial direction. On the other hand, it is provided at a position closer to the eccentric shaft portion 41A than the rotation reference point P.

  Next, FIG. 7 shows a third embodiment of the present invention. The feature of this embodiment is that a crankshaft is provided with a hollow portion and an adjustment balance weight for finely adjusting the weight balance is provided. It is in the configuration. In the present embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  Reference numeral 51 denotes a crankshaft according to the present embodiment. The crankshaft 51 is configured in substantially the same manner as the crankshaft 3 according to the first embodiment, and both end sides thereof can be rotated using a main bearing (not shown). It is supported. As a result, the crankshaft 51 is rotatable around the axis O1-O1. In addition, for example, two eccentric shaft portions 51A and 51B are provided in the intermediate portion in the axial direction of the crankshaft 51 so as to be separated from the axis O1-O1 serving as the rotation center by a predetermined dimension in the radial direction. The eccentric shaft portions 51A and 51B are eccentric to the opposite sides in the diametrical direction with respect to the axis O1-O1. One end of the crankshaft 51 is a protruding end 51C, and the protruding end 51C is connected to a drive source (none of which is shown) via a pulley.

  Reference numeral 52 denotes a hollow portion provided in the crankshaft 51. The hollow portion 52 is formed in substantially the same manner as the hollow portion 4 according to the first embodiment, and extends from the other end of the crankshaft 51 to the length of the crankshaft 51. It bends and extends along the vertical direction. And the hollow part 52 is provided in the inside of eccentric shaft part 51A among the eccentric shaft parts 51A and 51B of two places, for example. Thereby, the hollow part 52 is arrange | positioned on the opposite side of the hollow part 52 on both sides of axis line O1-O1 used as the rotation center about the gravity center position of the crankshaft 51. As shown in FIG.

  53 is an adjustment balance weight for finely adjusting the weight balance provided on the crankshaft 51. The adjustment balance weight 53 is located between, for example, the eccentric shaft portions 51A and 51B of the crankshaft 51, It is provided on the opposite side to the eccentric shaft portion 51A from the axis O1-O1 with respect to the radial direction and at a position closer to the eccentric shaft portion 51A than to the rotation reference point P with respect to the axial direction.

  Thus, also in this embodiment, it is possible to obtain substantially the same operational effects as those in the first embodiment. In particular, in the present embodiment, since the crankshaft 51 is provided with the hollow portion 52 and the adjustment balance weight 53 is provided, the center of gravity of the crankshaft 51 can be shifted by the hollow portion 52, and the adjustment balance weight 53 is adjusted. The size and weight are smaller than the balance weight of the prior art, and the weight can be reduced. Further, since the adjusting balance weight 53 is provided on the crankshaft 51, the position of the center of gravity of the crankshaft 51 can be adjusted by adjusting the size, shape, etc. of the adjusting balance weight 53. For this reason, after the compressor 1 is assembled, the center of gravity of the crankshaft 51 can be adjusted while confirming the actual vibration state of the compressor 1.

  In the third embodiment, the adjustment balance weight 53 is provided between the eccentric shaft portions 51A and 51B of the crankshaft 51. However, the present invention is not limited to this. For example, an adjustment balance weight 53 ′ may be provided on both ends of the crankshaft 51 as in a second modification shown in FIG. 8. In this case, the adjustment balance weight 53 ′ may be provided only at one of both ends of the crankshaft 51, or may be provided at both ends.

  In each of the above embodiments, the crankshafts 3, 41, 51 are provided with the hollow portions 4, 42A, 52 that bend and extend from the other end. However, the present invention is not limited to this, and as in the third modification shown in FIG. 9, the crankshaft 3 has a hollow extending from the intermediate position between the eccentric shaft portions 3A and 3B toward the inside of the eccentric shaft portion 3A. It is good also as a structure which provides part 4 '.

  In each of the above embodiments, the pistons 10, 15, 20, and 25 and the connecting rods 12, 17, 22, and 27 that constitute the cylinders 8, 13, 18, and 23 are exemplified as separate parts. I gave it as an explanation. However, the present invention is not limited to this, and the present invention may be applied to a compressor having a swinging piston (locking piston) in which a piston and a connecting rod are integrally formed or fixedly connected to each other. Good.

  In each of the above embodiments, the horizontally opposed four-cylinder type air compressor 1 is described as an example of the reciprocating compressor. However, the present invention is not limited to this, and may be applied to horizontally opposed compressors such as 2-cylinder and 6-cylinder. In addition, an in-line type compressor in which each cylinder is arranged in series on one side in the diameter direction of the crankshaft, a V-type compressor in which each cylinder is arranged in a V shape across the crankshaft, or three cylinders You may apply to the compressor etc. which became the structure which hardly produces the volume fluctuation | variation in a crankcase by arrange | positioning at intervals of 120 degrees. Furthermore, the present invention can be applied to various compressors that compress a gas other than air including a refrigerant.

1 is a cross-sectional view showing a horizontally opposed four-cylinder air compressor according to a first embodiment of the present invention. It is sectional drawing which looked at the air compressor from the arrow II-II direction in FIG. It is a front view which shows the crankshaft in FIG. It is a front view which shows the crankshaft by a comparative example. It is a front view which shows the crankshaft by 2nd Embodiment. It is a front view which shows the crankshaft by a 1st modification. It is a front view which shows the crankshaft by 3rd Embodiment. It is a front view which shows the crankshaft by a 2nd modification. It is a front view which shows the crankshaft by a 3rd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air compressor 3,41,51 Crankshaft 4,42A, 52,4 'Hollow part 6,7 Main bearing 8,13,18,23 Cylinder 9,14,19,24 Cylinder 10,15,20,25 Piston 12, 17, 22, 27 Connecting rod 42 Low density part (different density part)
42B Encapsulating member 43 High density part (different density part)
53,53 'Balance weight for adjustment

Claims (3)

A crankshaft that is rotationally driven by a drive source, a cylinder on which a cylinder head having a suction port and a discharge port is mounted, and a gas that is sucked from the suction port by reciprocating in the cylinder, In a reciprocating compressor comprising a piston that discharges compressed gas from a connecting rod that connects the piston and a crankshaft,
A reciprocating compressor, wherein the crankshaft is provided with a hollow portion that is partially hollow to suppress vibration during rotation of the crankshaft. A crankshaft that is rotationally driven by a drive source, a cylinder on which a cylinder head having a suction port and a discharge port is mounted, and a gas that is sucked from the suction port by reciprocating in the cylinder, In a reciprocating compressor comprising a piston that discharges compressed gas from a connecting rod that connects the piston and a crankshaft,
A reciprocating compressor characterized in that the crankshaft is provided with a different density part, part of which has a different density, to suppress vibration during rotation of the crankshaft.   The reciprocating compressor according to claim 1 or 2, wherein the crankshaft is configured to be provided with support portions for rotationally supporting at both ends thereof.

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