JP6476093B2 - Screw compressor - Google Patents

Description

  The present invention relates to a screw compressor, and more particularly to a screw compressor having a connection structure between a motor shaft and a rotor shaft.

  In the screw compressor, a pair of male and female screw rotors are rotationally driven by a motor. The rotational driving force of the motor is transmitted to the screw rotor in various modes. For example, there is a configuration in which the motor shaft of the motor is connected to the rotor shaft of the screw rotor via a connecting means (Patent Literature). 1).

Special table 2015-508858 gazette

  In the screw compressor disclosed in Patent Document 1, the motor shaft and the rotor shaft are configured separately, and the motor shaft includes a recess for inserting the end of the rotor shaft and a bolt formed with a male screw. A passage for inserting the shaft portion, and a female screw is formed at the end of the rotor shaft. With the end of the rotor shaft inserted into the recess of the motor shaft, the male shaft of the bolt is screwed into the end of the rotor shaft and the bolt is tightened to connect the motor shaft to the rotor shaft.

  In such a connection structure, the end surface of the end of the rotor shaft and the hole bottom surface of the recess of the motor shaft abut, and the motor shaft and the rotor are caused by the frictional force acting on the contact surface where the end surface and the hole bottom surface abut. Torque is transmitted to and from the shaft. In order to insert the end of the rotor shaft into the recess of the motor shaft, a minute shaft gap is provided between the end of the rotor shaft and the recess of the motor shaft.

  In the screw compressor disclosed in Patent Document 1, since the motor is of a vertical type in which the motor is disposed above the screw rotor, oil from the bearing is difficult to enter the shaft gap. However, if the horizontal shaft type in which the shafts of the motor and the screw rotor extend in the horizontal direction is used, the lubricating oil that lubricates the bearings travels along the rotor shaft and enters the shaft clearance.

  The lubricating oil that has entered the shaft clearance turns around the contact surface between the end of the rotor shaft and the recess of the motor shaft, so that the frictional force acting on the contact surface decreases, and the motor shaft and the rotor shaft Torque transmitted between the two is reduced.

  Therefore, a technical problem to be solved by the present invention is to provide a screw compressor that reliably transmits torque between a motor shaft and a rotor shaft even if the lubricating oil travels along a shaft extending in the horizontal direction. It is to be.

  In order to solve the above technical problem, according to the present invention, the following screw compressor is provided.

That is, a pair of male and female screw rotors, which are housed in the rotor chamber of the compressor body, and mesh with each other;
A motor that drives the rotor shaft of one of the male and female screw rotors;
The rotor shaft and the motor shaft of the motor are separate and disposed coaxially in the horizontal direction,
In the rotor shaft and the motor shaft, the shaft diameter of one of the shafts is larger than the shaft diameter of the other shaft,
The one shaft having a large diameter is formed with a connecting hole for inserting the other shaft,
With the other shaft inserted into the connecting hole formed in the one shaft, the rotor shaft is supported at both ends by an intermediate bearing portion that is lubricated by circulating the rotor side bearing portion and lubricating oil. And the motor shaft is supported by a motor side bearing portion,
A coupling member that integrally connects the one shaft and the other shaft is disposed between the inner peripheral surface of the one shaft and the outer peripheral surface of the other shaft, and is formed on the rotor shaft. The one shaft and the other shaft are fastened by a fastening member screwed into the screw hole.

  According to the above configuration, one shaft and the other shaft are integrally connected by the coupling member, and one shaft and the other shaft are fastened by the fastening member, so that the lubricating oil is in the horizontal direction (sideways). Even if the shaft extending to the shaft is transmitted, torque can be reliably transmitted between the motor shaft and the rotor shaft. Further, by loosening or tightening the fastening member, the motor shaft and the rotor shaft can be easily separated or assembled, respectively.

The cross-sectional view of the screw compressor which concerns on 1st Embodiment of this invention. The longitudinal cross-sectional view of the screw compressor shown in FIG. The fragmentary sectional view of the motor shaft in the screw compressor shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. The principal part expanded sectional view concerning the modification of 1st Embodiment. The cross-sectional view of the screw compressor which concerns on 2nd Embodiment of this invention. The longitudinal cross-sectional view of the screw compressor shown in FIG. The fragmentary sectional view of the motor shaft in the screw compressor shown in FIG. The principal part expanded sectional view of the screw compressor shown in FIG.

  First, a screw compressor 1 according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4A.

  FIG. 1 is a cross-sectional view of a screw compressor 1 according to the first embodiment. This screw compressor 1 is an oil-free screw compressor. A screw rotor 3 composed of a pair of male rotor 3a and female rotor 3b meshing with each other in an oil-free state is accommodated in a rotor chamber 17 formed in the rotor casing 4 of the oil-free compressor body 2. A bearing casing 7 is attached to one end of the rotor casing 4, and a motor casing 5 is attached to the other end of the rotor casing 4. The motor casing 5 of the motor 6 includes a motor casing main body 5a, a cooling jacket 8, and a cover 9. A rotor (rotor) 6a and a stator (stator) 6b are accommodated in the motor casing body 5a. The end of the motor casing 5 is closed with a cover 9.

  A gas discharge port (not shown) is formed on the motor 6 side of the rotor casing 4, and a gas suction port (not shown) is formed on the rotor casing 4 on the opposite side of the motor 6. Timing gears that mesh with each other are attached to shaft ends of the male rotor 3a and the female rotor 3b opposite to the motor 6. Normally, the male rotor 3 a is driven to rotate by the motor 6. The rotation of the motor shaft 31 of the motor 6 causes the male rotor shaft 21 of the male rotor 3a to rotate, and the female rotor shaft 22 of the female rotor 3b rotates so as to synchronize with the male rotor shaft 21 via the timing gear. .

  The motor 6 is a drive source for rotating the rotor shaft (usually the male rotor shaft 21) of the screw rotor 3. The rotation speed of the motor 6 is controlled by an inverter (not shown), and the motor 6 is operated at a high speed rotation exceeding 20000 rpm, for example. The rotor 6a of the motor 6 is fixed to the outer peripheral portion of the motor shaft 31, and the stator 6b is disposed apart from the rotor 6a. In the motor casing 5, the cooling jacket 8 is disposed between the stator 6b and the motor casing body 5a.

  The motor shaft 31 has a plurality of different-diameter shaft portions that reduce the diameter from the screw rotor 3 side toward the motor-side bearing portion 13 side. The motor shaft 31 includes, for example, a first shaft portion 44 and a second shaft portion 45. The large-diameter first shaft portion 44 is locked to the side end surface of the rotor 6a. The rotor 6a is attached to the second shaft portion 45 having a small diameter. The connection hole 32 extends in the axial direction over the entire first shaft portion 44 and a part of the second shaft portion 45. The center hole 33 extends in the axial direction over the remaining portion of the second shaft portion 45. The rotor 6 a is fixed to the motor shaft 31 by tightening with the mounting bolts 38 in a state where the flange portion of the bearing support 37 is in contact with each of the second shaft portion 45 and the side end surface of the rotor 6 a.

  The cooling jacket 8 is mounted along the inner side surface of the motor casing main body 5a, and the cooling jacket 8 is fixed to the motor casing main body 5a by tightening with a bolt while the flange portions are in contact with each other. In the cooling jacket portion 8 a of the cooling jacket 8, a cooling passage 8 b for flowing a liquid refrigerant such as cooling water or cooling oil is formed. Leakage of the liquid refrigerant flowing in the cooling passage 8b is prevented by packing provided on both sides in the axial direction of the cooling passage 8b.

  The male rotor shaft 21 of the screw rotor 3 and the motor shaft 31 of the motor 6 are configured separately, and a key to be described later is provided so that both the shafts 21 and 31 extend coaxially in the horizontal direction (lateral direction). 41 (coupling member) is integrally connected. The opposite side of the motor 6 in the male rotor shaft 21 is supported on the bearing casing 7 by the rotor-side bearing portion 11. The motor 6 side of the male rotor shaft 21 is supported on the rotor casing 4 by the intermediate bearing portion 12. That is, the male rotor shaft 21 is supported by the rotor-side bearing portion 11 and the intermediate bearing portion 12 in both ends. The bearing support 37 fixed to the motor side end of the motor shaft 31 is supported by the cover 9 by the motor side bearing 13. Therefore, the integrally connected male rotor shaft 21 and the motor shaft 31 extend coaxially in the horizontal direction (lateral direction), and at three locations of the rotor side bearing portion 11, the intermediate bearing portion 12, and the motor side bearing portion 13. Supported (that is, supported at three points). On the other hand, the female rotor shaft 22 of the female rotor 3 b is supported by both the bearing casing 7 and the rotor casing 4 by the rotor-side bearing portion 15 and the intermediate bearing portion 16.

  The rotor-side bearing portion 11 includes, for example, a thrust bearing (4-point contact ball bearing) 11a and a radial bearing (roller bearing) 11b. The intermediate bearing portion 12 includes, for example, a radial bearing (roller bearing) 12a and a thrust bearing (four-point contact ball bearing) 12b. The motor side bearing portion 13 is constituted by, for example, a radial bearing (deep groove ball bearing). Moreover, the rotor side bearing part 15 is comprised from the thrust bearing (4-point contact ball bearing) 15a and the radial bearing (roller bearing) 15b, for example. The intermediate bearing portion 16 includes, for example, a radial bearing (roller bearing) 16a and a thrust bearing (four-point contact ball bearing) 16b. Each bearing uses an open-type bearing so as to be lubricated by circulating lubricating oil.

  The male rotor shaft 21 between the rotor-side bearing portion 11 and the male rotor 3a is provided with a shaft seal portion 14a. The male rotor shaft 21 between the male rotor 3a and the intermediate bearing portion 12 is provided with a shaft sealing portion 14c. A shaft sealing portion 14b is provided on the female rotor shaft 22 between the rotor-side bearing portion 15 and the female rotor 3b. A shaft sealing portion 14 d is provided on the female rotor shaft 22 between the female rotor 3 b and the intermediate bearing portion 16. Each shaft seal part 14a, 14b, 14c, 14d is provided with the mechanical seal as a visco seal and an air seal, for example as an oil seal. The visco seal provided on the bearing side prevents the lubricating oil from flowing into the rotor chamber 17. The mechanical seal provided on the screw rotor 3 side prevents inflow of lubricating oil into the rotor chamber 17 and excessive leakage of compressed gas from the rotor chamber 17.

  The protruding end portion of the bearing support 37 is inserted into the center hole 33 of the motor shaft 31 and is tightened with the mounting bolt 38 in a state where the flange portion of the bearing support 37 is in contact with the side end surface of the motor shaft 31. . Thus, the bearing support 37 is fixed to the motor shaft 31 and one end of the center hole 33 on the motor side bearing portion 13 side is closed. As shown in FIG. 3, the inner ring of the motor side bearing portion 13 is positioned so as not to move in the axial direction by a stop ring 61 disposed on the bearing support 37. On the other hand, since the motor-side bearing portion 13 is attached to the bearing mounting hole 9a of the cover 9 with a clearance fit, the outer ring of the motor-side bearing portion 13 can move in the axial direction. That is, the motor side bearing portion 13 is assembled to the motor 6 so as to allow sliding in the axial direction on the outer ring. According to this configuration, even if the motor shaft 31 expands and contracts due to thermal expansion, it is possible to prevent an unreasonable load from being applied to the motor-side bearing portion 13.

  The cover 9 is attached to the cooling jacket 8 so as to close the opening of the motor casing 5. The cover 9 is fixed to the cooling jacket 8 by tightening with a bolt while the flange portion of the cover 9 is in contact with the side end surface of the cooling jacket 8. The bearing casing 7 is formed with an oil supply port (not shown) for supplying lubricating oil to the rotor side bearing portions 11 and 15. In the rotor casing 4, an intermediate oil supply port 64 and an oil supply hole 82 a for supplying lubricating oil to the intermediate bearing portions 12 and 16 are formed. The cover 9 is formed with a motor-side oil supply port 9 c for supplying lubricating oil to the motor-side bearing portion 13. One end of the oil supply hole 82a communicates with the intermediate oil supply port 64, and the other end communicates with a space formed between the radial bearing 12a (16a) and the thrust bearing 12b (16a). Further, the rotor casing 4 includes an intermediate communication portion 54 having one end communicating with a gap formed between the radial bearing 12 a and the intermediate shaft sealing portion 14 a and the other end communicating with the motor chamber 20. The lubricating oil that is about to flow from the radial bearing 12 a to the screw rotor 3 side flows into the motor chamber 20 through the intermediate communication portion 54. An intermediate oil discharge port 66 is formed at the bottom of the motor chamber 20 on the intermediate bearing portion 12 side, and a motor side bearing oil discharge port 78 is formed at the bottom of the motor chamber 20 on the motor side bearing portion 13 side. The lubricating oil collected at the bottom of the motor chamber 20 is discharged out of the motor chamber 20 through an intermediate oil outlet 66 and a motor side bearing oil outlet 78 as an oil outlet, and is collected in an oil tank (not shown). Is done.

  The shaft diameter of the motor shaft 31 of the motor 6 is larger than the shaft diameter of the male rotor shaft 21 of the screw rotor 3. A connecting hole 32 for inserting the connecting end 24 on the motor 6 side of the male rotor shaft 21 is formed in the motor shaft 31 having a large diameter. The motor shaft 31 is formed with a center hole 33 having a diameter larger than that of the connection hole 32. By the center hole 33 and the connecting hole 32, a through-hole penetrating the inside of the motor shaft 31 in the axial direction is formed in the motor shaft 31, and the motor shaft 31 has a hollow structure. A step is formed at the boundary between the large diameter center hole 33 and the small diameter connection hole 32. The fastening flange 27 can be freely inserted through the center hole 33 due to the level difference of the through-hole penetrating the motor shaft 31, but it is a dead end with respect to the connection hole 32.

  On the inner peripheral surface 31b of the connecting hole 32 provided in the motor shaft 31, for example, a second key groove 31a having a rectangular cross section and a concave shape is formed. On the outer peripheral surface 21b of the connecting end 24 provided on the male rotor shaft 21, for example, a first key groove 24a having a rectangular cross section and a concave shape is formed. A key groove 42 having a rectangular cross section is formed in the axial direction by the first key groove 24a and the second key groove 31a. With the connecting end 24 inserted into the connecting hole 32, the key 41 having a rectangular cross-section has an inner peripheral surface 31 b of the connecting hole 32 of the motor shaft 31 and an outer peripheral surface 21 b of the connecting end 24 of the male rotor shaft 21. Is interposed between the two. At this time, the key 41 is fitted in the key groove 42, and the key 41 is fitted in the key groove 42. Therefore, the key 41 functions as a coupling member that integrally connects the motor shaft 31 and the male rotor shaft 21.

  On the side of the motor-side bearing portion 13 of the connecting end portion 24, a fastening end portion 25 in which a screw hole 26 is formed is provided on the shaft end surface side. The screw portion 28 b of the fastening bolt 28 is screwed into the screw hole 26 of the fastening end portion 25. A fastening bolt 28 as a fastening member is inserted through the screw insertion hole of the fastening flange 27. When the fastening bolt 28 is tightened in a state where the fastening flange 27 is inserted into the center hole 33 and engaged with the step of the through hole, the connecting end portion 24 of the male rotor shaft 21 is drawn toward the motor side bearing portion 13. The head 28 a of the fastening bolt 28 is engaged with the fastening flange 27. As a result, the motor shaft 31 and the male rotor shaft 21 are fastened by the fastening bolt 28. Thus, the motor shaft 31 and the male rotor shaft 21 are fastened by the fastening bolts 28 in a state where the motor shaft 31 and the male rotor shaft 21 are integrally connected by the key 41.

  The motor shaft 31 and the male rotor shaft 21 are integrally connected by a key 41 as a coupling member, and the motor shaft 31 and the male rotor shaft 21 fastened by a fastening bolt 28 as a fastening member are a single shaft body. Work as. Since the fitting structure using the key 41 is not affected by the lubricating oil, even if the lubricating oil enters the connecting hole 32 through the male rotor shaft 21 extending in the horizontal direction, the motor shaft Torque can be reliably transmitted between 31 and the male rotor shaft 21.

  At this time, the head portion 28a of the fastening bolt 28 is positioned in a center hole 33 formed so as to penetrate the motor shaft 31 in the axial direction. Specifically, the head portion 28 a is immersed in the center hole 33 of the motor shaft 31 so as to be positioned near the shaft end surface of the fastening end portion 25 of the male rotor shaft 21. That is, the axial length of the fastening bolt 28 is configured to be short. According to the said structure, the influence of the thermal expansion of the fastening bolt 28 decreases, and it can clamp | tighten reliably. The connection end 24 and the fastening end 25 of the male rotor shaft 21 and the connection hole 32 and the center hole 33 of the motor shaft 31 extend coaxially.

  A radial bearing 12 a of the intermediate bearing portion 12 is attached to the motor casing 6 side of the rotor casing 4. The position of the inner ring of the radial bearing 12a is fixed with respect to the male rotor shaft 21, and the position of the outer ring of the radial bearing 12a is fixed with respect to the rotor casing 4 by a retaining ring. A bearing support member 19 is attached to the rotor 6 on the motor 6 side via the spacer 18. By tightening with bolts, the bearing support member 19 and the spacer 18 are fixed to the motor 6 side of the rotor casing 4. The position of the inner ring of the thrust bearing 12b is fixed to the male rotor shaft 21 by a locking nut 23a.

  Similarly, a radial bearing 16 a of the intermediate bearing portion 16 is attached to the motor casing 6 of the rotor casing 4. The position of the inner ring of the radial bearing 16a is fixed with respect to the female rotor shaft 22, and the position of the outer ring of the radial bearing 16a is fixed with respect to the rotor casing 4 by a retaining ring. The position of the inner ring of the thrust bearing 16b is fixed to the female rotor shaft 22 by a locking nut 23b.

  In addition, the inner ring, outer ring, and rolling elements constituting the bearing are usually made of steel and have conductivity. Therefore, the high frequency current from the inverter circuit of the motor 6 flows to the intermediate bearing portion 12 and the motor side bearing portion 13 that support the motor shaft 31 of the motor 6, and the outer ring and the inner ring of the intermediate bearing portion 12 and the motor side bearing portion 13. A shaft voltage is generated in the meantime, which causes an electrolytic corrosion phenomenon that damages the bearing. Therefore, the intermediate bearing portion 12 and the motor side bearing portion 13 are electrically insulated. The bearing is electrically insulated because, for example, the rolling element of the bearing is made of an inorganic insulating material such as ceramics, and the outer surface of at least one of the inner ring and outer ring of the bearing is epoxy resin, unsaturated polyester resin, etc. It is covered with an organic insulating material. Moreover, in the support member and casing which support a bearing, the part contact | abutted to a bearing may be covered with the insulating material. Since the intermediate bearing portion 12 and the motor-side bearing portion 13 are electrically insulated in this way, the electric corrosion phenomenon that the bearings 12 and 13 are damaged by the high-frequency current from the inverter circuit of the motor 6 hardly occurs. it can.

  In the above embodiment, in the male rotor shaft 21 and the motor shaft 31, the shaft diameter of the motor shaft 31 acting as one shaft is larger than the shaft diameter of the male rotor shaft 21 serving as the other shaft, and is formed in the motor shaft 31. The motor shaft 31 is connected to the male rotor shaft 21 by inserting the connecting end portion 24 of the male rotor shaft 21 into the connecting hole 32 formed.

  On the other hand, as shown in FIG. 4B, the shaft diameter of the male rotor shaft 21 is larger than the shaft diameter of the motor shaft 31, the male rotor shaft 21 serves as one shaft, and the motor shaft 31 serves as the other shaft. Can be configured to work. In the modification shown in FIG. 4B, a second key groove 31a having a rectangular cross section and a concave shape is formed on the outer peripheral surface 34b of the connecting end 34 provided on the motor shaft 31, for example. On the inner peripheral surface 24b of the connection hole 23 provided in the male rotor shaft 21, for example, a first key groove 24a having a rectangular cross section and a concave shape is formed. A key groove 42 having a rectangular cross section is formed in the axial direction by the first key groove 24a and the second key groove 31a.

  In a state where the connecting end 34 of the motor shaft 31 is inserted into the connecting hole 23 of the male rotor shaft 21, the key 41 having a rectangular cross section is formed between the outer peripheral surface 34 b of the connecting end 34 of the motor shaft 31 and the male rotor shaft 21. It is interposed between the inner peripheral surface 24 b of the connecting hole 23. At this time, the key 41 is fitted in the key groove 42, and the key 41 is fitted in the key groove 42. Therefore, the key 41 functions as a coupling member that integrally connects the motor shaft 31 and the male rotor shaft 21.

  Next, a second embodiment of the present invention will be described in detail with reference to FIGS. In the second embodiment, components having the same functions as the components in the first embodiment are given the same reference numerals, and redundant descriptions are omitted.

  In the screw compressor 1 according to the second embodiment, the motor shaft 31 and the male rotor shaft 21 are integrally connected by a tapered ring 52 as a coupling member.

  The taper ring 52 is also referred to as a spun ring, and connects the motor shaft 31 and the male rotor shaft 21 using frictional force generated on the peripheral surface of the ring arranged in the mounting space. The taper ring 52 is configured by combining a wedge-shaped inner ring 52a having one inclined surface and a wedge-shaped outer ring 52b having the other inclined surface engaged with the one inclined surface.

  A coupling hole 35 is formed between the outer peripheral surface 21 b of the connecting end 24 of the male rotor shaft 21 and the inner peripheral surface 31 b of the connecting hole 32 of the motor shaft 31. The coupling hole 35 is an annular mounting space in which the diameter of the end of the communication hole 32 is increased, and opens to the screw rotor 3 side. The taper ring 52 is disposed in the coupling hole 35. A sleeve 53 is provided on the taper ring 52 on the screw rotor 3 side. The sleeve 53 abuts on the pressing step portion 29 having a diameter larger than that of the connecting end portion 24. By the sleeve 53, the axis orthogonal surface of the inner ring 52 a is pressed in the direction of the motor side bearing portion 13. At this time, the outer peripheral surface of the outer ring 52 b is pressed radially outward and is in close frictional engagement with the inner peripheral surface 31 b of the coupling hole 35. At the same time, the inner peripheral surface of the inner ring 52a is pressed radially inward and is in close frictional engagement with the outer peripheral surface 21b of the connecting end 24. Therefore, the motor shaft 31 and the male rotor shaft 21 are integrally connected by a frictional force on the inner peripheral surface and the outer peripheral surface of the taper ring 52.

  The outer peripheral surface of the outer ring 52 b is in close contact with the inner peripheral surface 31 b of the coupling hole 35, and the inner peripheral surface of the inner ring 52 a is in close contact with the outer peripheral surface 21 b of the connecting end portion 24. As a result, there is substantially no gap between the outer peripheral surface 21b of the connecting end portion 24 and the inner peripheral surface 31b of the coupling hole 35. For this reason, even if the lubricating oil from the intermediate bearing portion 12 travels along the male rotor shaft 21 extending in the horizontal direction, it is between the outer peripheral surface 21b of the coupling end portion 24 and the inner peripheral surface 31b of the coupling hole 35. There is virtually no entry. Therefore, torque can be reliably transmitted between the motor shaft 31 and the male rotor shaft 21. Further, the magnitude of the transmission torque is adjusted by increasing / decreasing the number of taper rings 52 arranged in the axial direction between the outer peripheral surface 21b of the coupling end portion 24 and the inner peripheral surface 31b of the coupling hole 35. be able to.

  In the second embodiment, the fastening structure using the fastening bolt 58 generates a pressing force of the pressing step portion 29 in the direction of the motor side bearing portion 13 and fastens the motor shaft 31 and the male rotor shaft 21. . As a fastening structure using fastening bolts, the head 28 a of the fastening bolt 28 may be located inside the center hole 33 of the motor shaft 31 as in the first embodiment described above. Specifically, the head portion 28 a may be immersed in the center hole 33 of the motor shaft 31 so that the head portion 28 a is positioned in the vicinity of the shaft end surface of the fastening end portion 25 of the male rotor shaft 21. However, in the second embodiment, a fastening structure different from that in the first embodiment is used.

  In the fastening structure of the second embodiment, the head 58a of the fastening bolt 58 is located outside the motor shaft 31, and the fastening structure will be described.

  The motor shaft 31 is formed with a connection hole 32 for inserting the connection end 24 on the motor 6 side of the male rotor shaft 21. The motor shaft 31 is formed with a bolt hole 55 having a smaller diameter than the connection hole 32. The shaft portion of the fastening bolt 58 is inserted into the bolt hole 55. A through hole that penetrates the motor shaft 31 in the axial direction is formed in the motor shaft 31 by the small-diameter bolt hole 55 and the large-diameter connection hole 32, and the motor shaft 31 has a hollow structure.

  The motor shaft 31 has a plurality of different-diameter shaft portions that reduce the diameter from the screw rotor 3 side toward the motor-side bearing portion 13 side. The motor shaft 31 includes, for example, a first shaft portion 44, a second shaft portion 45, a third shaft portion 46, and a fourth shaft portion 47. The connecting hole 32 extends over the entire first shaft portion 44 and a part of the second shaft portion 45. The bolt hole 55 extends over the remaining portion of the second shaft portion 45, all of the third shaft portion 46, and all of the fourth shaft portion 47. The rotor 6 a attached to the second shaft portion 45 is fixed to the motor shaft 31 by the first shaft portion 44 on the screw rotor 3 side and the stopper 63 attached to the third shaft portion 46. . The fourth shaft portion 47 on the motor side bearing portion 13 side functions as a bearing support portion 47. The bearing support portion 47 is supported by the cover 9 by the motor side bearing portion 13.

  The inner ring of the motor side bearing portion 13 is positioned so as not to move in the axial direction by a retaining ring 61 disposed on the bearing support 37. On the other hand, the outer ring of the motor side bearing portion 13 can move in the axial direction because the motor side bearing portion 13 is attached to the bearing mounting hole 9a with a clearance fit. That is, the motor side bearing portion 13 is assembled to the motor 6 so as to allow sliding in the axial direction on the outer ring.

  A spring member 62 is disposed between the outer ring of the motor side bearing portion 13 and the cover 9. The spring member 62 is, for example, a wave spring, and the outer ring of the motor side bearing portion 13. It is biased in the axial direction on the screw rotor 3 side. According to this configuration, even if the motor shaft 31 expands and contracts due to thermal expansion, the outer ring of the motor side bearing portion 13 moves while being urged in the axial direction. It is less affected and can maintain bearing pressure.

  A screw hole 56 is formed on the shaft end surface of the connecting end portion 24 on the motor side bearing portion 13 side. The screw portion 58 b of the fastening bolt 58 is screwed into the screw hole 56 of the connecting end portion 24. When the fastening bolt 58 is tightened, the connecting end portion 24 of the male rotor shaft 21 is drawn toward the motor side bearing portion 13, and the head 58 a of the fastening bolt 58 is locked to the side end surface of the bearing support portion 47. As a result, the motor shaft 31 and the male rotor shaft 21 are fastened by the fastening bolt 58. By configuring the head 58 a of the fastening bolt 58 to be located outside the motor shaft 31, it is possible to reduce the number of processing steps and the number of parts of the motor shaft 31 and simplify the fastening work using the fastening bolt 58.

  Therefore, in the screw compressor 1 of the second embodiment, the motor shaft 31 and the male rotor shaft 21 are fastened by the fastening bolt 58 in a state where the motor shaft 31 and the male rotor shaft 21 are integrally connected by the taper ring 52. Has been. According to this configuration, even if the lubricating oil from the intermediate bearing portion 12 is transmitted through the male rotor shaft 21 extending in the horizontal direction (lateral direction), the torque is reliably transmitted between the motor shaft 31 and the male rotor shaft 21. Can communicate. Moreover, the male rotor shaft 21 and the motor shaft 31 can be easily separated or assembled by loosening or tightening the fastening bolt 58, respectively.

  In the present invention, in the rotor shaft 21 (22) of the screw rotor 3 and the motor shaft 31 of the motor 6, the shaft diameter of one of the shafts 31 is larger than the shaft diameter of the other shaft 21. One shaft 31 having a diameter is formed with a connection hole 32 for inserting the other shaft 21. In this regard, in each of the above-described embodiments, the shaft diameter of the motor shaft 31 of the motor 6 is larger than the shaft diameter of the male rotor shaft 21 of the screw rotor 3, and with respect to the motor shaft 31 having a large diameter, A connection hole 32 for inserting the connection end 24 on the motor 6 side of the male rotor shaft 21 is formed. However, as in the modification shown in FIG. 4A, the male rotor shaft 21 of the screw rotor 3 is larger than the shaft diameter of the motor shaft 31 of the motor 6 and has a large diameter. On the other hand, the connection hole 23 for inserting the connection end 34 of the motor shaft 31 may be formed.

  In the embodiment described above, of the pair of male and female screw rotors 3, the rotor shaft of one screw rotor is connected to the male rotor shaft 21, and the motor shaft 31 of the motor 6 is connected to the male rotor shaft 21 of the screw rotor 3. ing. However, the rotor shaft of one screw rotor may be the female rotor shaft 22 and the motor shaft 31 may be coupled to the female rotor shaft 22.

  Further, the configurations of the rotor-side bearing portion 11, the intermediate bearing portion 12, and the motor-side bearing portion 13 and the configurations of the shaft seal portions 16a, 16b, 17a, and 17b are not limited to the above embodiment. The screw compressor 1 to which the above-described coupling members 41 and 52 are applied is rotationally driven at a low speed of about 3000 rpm by introducing cooling oil in addition to an oil-free one that is rotationally driven at a high speed of about 20000 rpm. An oil-cooled type may be used.

  As is clear from the above description, in the screw compressor 1 according to the present invention, a pair of male and female screw rotors 3 housed in the rotor chamber 17 of the compressor body 2 and the pair of male and female screw rotors. 3, the motor 6 that drives the rotor shaft 21 of one screw rotor, and the rotor shaft 21 and the motor shaft 31 of the motor 6 are separate and disposed coaxially in the horizontal direction. In the rotor shaft 21 and the motor shaft 31, the shaft diameter of one of the shafts 31 is larger than the shaft diameter of the other shaft 21. A connecting hole 32 for inserting the shaft 21 is formed, and the rotor shaft 21 is connected to the rotor-side bearing portion 11 in a state where the other shaft 21 is inserted into the connecting hole 32 formed in the one shaft 31. And lubricating oil The motor shaft 31 is supported by the motor-side bearing portion 13 and is integrally connected to the one shaft 31 and the other shaft 21. Coupling members 41, 52 are disposed between the inner peripheral surface 31 b of the one shaft 31 and the outer peripheral surface 21 b of the other shaft 21, and are inserted into screw holes 26, 56 formed in the rotor shaft 21. The one shaft 31 and the other shaft 21 are fastened by fastening members 28 and 58 that are screwed together.

  According to the above configuration, the one shaft 31 and the other shaft 21 are integrally connected by the coupling members 41 and 52, and the one shaft 31 and the other shaft 21 are fastened by the fastening members 28 and 58. Therefore, even if the lubricating oil from the intermediate bearing portion 12 is transmitted through the shafts 21 and 31 extending in the horizontal direction (lateral direction), the torque can be reliably transmitted between the motor shaft 31 and the rotor shaft 21. . Further, by loosening or tightening the fastening members 28 and 58, the motor shaft 31 and the rotor shaft 21 can be easily separated or assembled, respectively.

  The present invention can have the following features in addition to the above features.

  That is, the coupling member 41 is a key 41 that is fitted into a key groove 42 provided on the inner peripheral surface 31 b of the one shaft 31 and the outer peripheral surface 21 b of the other shaft 21. According to this configuration, since the fitting structure using the key 41 is not affected by the lubricating oil, the lubricating oil enters the connecting hole 32 through the shafts 21 and 31 extending in the horizontal direction. In addition, torque can be reliably transmitted between the motor shaft 31 and the male rotor shaft 21.

  The coupling member 52 is a tapered ring 52 composed of an inner ring 52a and an outer ring 52b with which the inclined surfaces engage with each other. According to this configuration, the processing of the one shaft 31 and the other shaft 21 is easy, and the motor shaft 31 and the rotor shaft 21 can be easily separated or assembled.

  The screw hole 26 is formed in the fastening end portion 25 of the rotor shaft 21, and the motor shaft 31 so that the head portion 28 a of the fastening member 28 is located near the shaft end surface of the fastening end portion 25. Is immersive inside. According to the said structure, the axial direction length of the fastening member 28 becomes short, the influence of the thermal expansion of the fastening member 28 decreases, and it can clamp | tighten reliably.

  The motor-side bearing portion 13 is assembled to the motor 6 so as to allow axial sliding on the outer ring. According to this configuration, the outer ring of the motor side bearing portion 13 can move in the axial direction, and even if the motor shaft 31 expands and contracts due to thermal expansion, an unreasonable load is applied to the motor side bearing portion 13. Can be prevented.

  The outer ring of the motor side bearing portion 13 is urged in the axial direction by a spring member 62. According to this configuration, even if the motor shaft 31 expands and contracts due to thermal expansion, the outer ring of the motor side bearing portion 13 moves while being urged in the axial direction. It is less affected and can maintain bearing pressure.

  The intermediate bearing portion 12 and the motor side bearing portion 13 are electrically insulated. According to the said structure, the electric corrosion phenomenon that the said bearings 12 and 13 are damaged by the high frequency current from the inverter circuit of the motor 6 can be made hard to produce.

  The compressor body 2 is an oil-free type provided with a pair of male and female screw rotors 3 that mesh with each other in an oil-free state, and the intermediate bearing portion 12 is located on the discharge side of the compressor body 2; The motor 6 includes an oil discharge port 66 for discharging the lubricating oil flowing through the intermediate bearing portion 12 and flowing into the motor chamber 20 of the motor 6 to the outside of the motor chamber 20. According to this configuration, since the lubricating oil can be actively flowed to the motor chamber 20 side where the coupling members 41 and 52 are located, the flow of the lubricating oil to the rotor chamber 17 side is suppressed as much as possible. be able to.

1: Screw compressor (oil-free screw compressor)
2: Compressor body 3: Screw rotor 3a: Male rotor 3b: Female rotor 4: Rotor casing 5: Motor casing 5a: Motor casing body 6: Motor 6a: Rotor (rotor)
6b: Stator (stator)
7: Bearing casing 8: Cooling jacket 9: Cover 9a: Bearing mounting hole 11: Rotor side bearing portion 12: Intermediate bearing portion 13: Motor side bearing portion 17: Rotor chamber 20: Motor chamber 21: Male rotor shaft (rotor shaft; The other axis)
21b: outer peripheral surface 22: female rotor shaft (rotor shaft)
24: Connection end 24a: First key groove (key groove)
25: Fastening end portion 26: Screw hole 27: Fastening flange 28: Fastening bolt (fastening member)
28a: head portion 28b: screw portion 29: pressing step portion 31: motor shaft (one shaft)
31a: Second keyway (keyway)
31b: Inner peripheral surface 32: Connection hole (through hole)
33: Center hole (through hole)
35: Coupling hole 36: Screw hole 37: Bearing support 41: Key (coupling member)
42: Keyway 47: Bearing support 52: Taper ring (coupling member)
53: Sleeve 55: Bolt hole (through hole)
56: Screw hole 58: Fastening bolt (fastening member)
61: Stop ring 62: Spring member

Claims (8)

A pair of male and female screw rotors, which are housed in the rotor chamber of the compressor body and mesh with each other;
A motor that drives the rotor shaft of one of the male and female screw rotors;
The rotor shaft and the motor shaft of the motor are separate and disposed coaxially in the horizontal direction,
In the rotor shaft and the motor shaft, the shaft diameter of one of the shafts is larger than the shaft diameter of the other shaft,
The one shaft having a large diameter is formed with a connecting hole for inserting the other shaft,
With the other shaft inserted into the connecting hole formed in the one shaft, the rotor shaft is lubricated by circulating a lubricant and a rotor side bearing provided on the opposite side of the motor. The motor shaft is supported by a motor side bearing portion provided on the opposite side of the rotor shaft, and is supported by both ends of the intermediate bearing portion.
A coupling member that integrally connects the one shaft and the other shaft is disposed between the inner peripheral surface of the one shaft and the outer peripheral surface of the other shaft, and is formed on the rotor shaft. A screw compressor in which the one shaft and the other shaft are fastened by a fastening member screwed into the screw hole. The screw compressor according to claim 1,
A screw compressor, wherein the coupling member is a key fitted in a key groove provided on the inner peripheral surface of the one shaft and the outer peripheral surface of the other shaft. The screw compressor according to claim 1,
A screw compressor, wherein the coupling member is a tapered ring including an outer ring and an inner ring with which the inclined surfaces are engaged with each other. In the screw compressor according to any one of claims 1 to 3,
The screw hole is formed in the fastening end of the rotor shaft;
A screw compressor, wherein the head of the fastening member is immersed in the motor shaft such that the head of the fastening member is located near the shaft end surface of the fastening end. The screw compressor according to any one of claims 1 to 4,
A screw compressor in which the motor side bearing portion is assembled to the motor so as to allow sliding in the axial direction on the outer ring. The screw compressor according to claim 5, wherein
A screw compressor in which an outer ring of the motor side bearing portion is urged in an axial direction by a spring member. The screw compressor according to any one of claims 1 to 6,
A screw compressor in which the intermediate bearing portion and the motor side bearing portion are electrically insulated. In the screw compressor according to any one of claims 1 to 7,
The compressor body is an oil-free type including a pair of male and female screw rotors that mesh with each other in an oil-free state,
The intermediate bearing portion is located on the discharge side of the compressor body;
A screw compressor, wherein the motor includes an oil discharge port for discharging the lubricating oil flowing through the intermediate bearing portion and flowing into the motor chamber of the motor to the outside of the motor chamber.

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