阅读说明：本技术 一种采用磁性行星转子轴系增速的多级压缩机 (Multistage compressor adopting magnetic planetary rotor shafting for speed increase ) 是由 袁军 钟仁志 于 2021-09-09 设计创作，主要内容包括：本发明涉及多级压缩机领域,尤其涉及一种采用磁性行星转子轴系增速的多级压缩机。该压缩机包括驱动轴系和多个从动轴系；驱动轴系包括驱动主轴、主轴轴承、电机转子和驱动磁钢,多个驱动磁钢沿着圆周方向固定设置在驱动主轴上；从动轴系包括从动主轴、从动轴承、从动磁钢和叶轮,多个从动轴系的从动主轴沿着圆周方向分布在驱动主轴外侧；多个从动磁钢沿着圆周方向固定设置在从动主轴上,并且相邻从动磁钢的N极和S极在径向反方向设置；多个从动磁钢的位置与驱动磁钢的位置相对应,并且驱动磁钢的数量与不同从动轴系的从动磁钢的数量之比与驱动主轴与相应从动轴系的增速比相同；该压缩机减小了整个设备的体积,同时提高了整个设备压缩比。(The invention relates to the field of multistage compressors, in particular to a multistage compressor adopting a magnetic planetary rotor shaft system for increasing speed. The compressor comprises a driving shaft system and a plurality of driven shaft systems; the driving shaft system comprises a driving main shaft, a main shaft bearing, a motor rotor and a plurality of driving magnetic steels, wherein the plurality of driving magnetic steels are fixedly arranged on the driving main shaft along the circumferential direction; the driven shaft system comprises driven main shafts, driven bearings, driven magnetic steel and impellers, and the driven main shafts of the driven shaft systems are distributed on the outer side of the driving main shaft along the circumferential direction; the plurality of driven magnetic steels are fixedly arranged on the driven main shaft along the circumferential direction, and the N poles and the S poles of the adjacent driven magnetic steels are arranged in opposite directions in the radial direction; the positions of the driven magnetic steels correspond to the positions of the driving magnetic steels, and the ratio of the number of the driving magnetic steels to the number of the driven magnetic steels of different driven shafts is the same as the speed increasing ratio of the driving main shaft to the corresponding driven shaft; the compressor reduces the volume of the whole equipment and simultaneously improves the compression ratio of the whole equipment.)

1. A multi-stage compressor adopting a magnetic planetary rotor shaft system for increasing speed is characterized by comprising a shell (1), a driving shaft system (2), a plurality of driven shaft systems (3) and a volute (4), wherein a motor stator (11) is fixedly embedded in an inner hole of the shell (1); the driving shaft system (2) comprises a driving main shaft (21), a main shaft bearing (22), a motor rotor (23) and driving magnetic steel (24), wherein the position of the motor rotor (23) corresponds to that of the motor stator (11); a plurality of driving magnetic steels (24) are fixedly arranged on the driving main shaft (21) along the circumferential direction, and the N poles and the S poles of the adjacent driving magnetic steels (24) are arranged in the opposite directions in the radial direction; the driven shaft systems (3) comprise driven main shafts (31), driven bearings (32), driven magnetic steel (33) and impellers (34), and the driven main shafts (31) of the driven shaft systems (3) are distributed on the outer side of the driving main shaft (21) along the circumferential direction; a plurality of driven magnetic steels (33) are fixedly arranged on the driven main shaft (31) along the circumferential direction, and the N pole and the S pole of the adjacent driven magnetic steels (33) are arranged in the opposite direction of the radial direction; the positions of the driven magnetic steels (33) correspond to the positions of the driving magnetic steels (24), and the ratio of the number of the driving magnetic steels (24) to the number of the driven magnetic steels (33) of different driven shafts (3) is the same as the speed increasing ratio of the driving main shaft (21) to the corresponding driven shafts (3); the impellers (34) are fixed at one end of the driven main shaft (31), and the impellers (34) of the driven shaft systems (3) are respectively positioned in corresponding compression passages of the volute (4).

2. The multistage compressor adopting the magnetic planetary rotor shaft system for increasing the speed is characterized in that the casing (1) comprises a motor barrel (12), a front bearing seat (13) and a rear bearing seat (14), the front bearing seat (13) and the rear bearing seat (14) are respectively fixed at two ends of the motor barrel (12), and the motor stator (11) is fixedly embedded in a corresponding inner hole of the motor barrel (12).

3. The multistage compressor for increasing the speed by using the magnetic planetary rotor shaft system as claimed in claim 2, wherein the front bearing seat (13) is provided with a plurality of driven bearing holes (131), and the rear bearing seat (14) is provided with a driving bearing hole (141); the main shaft bearing (22) is positioned in the main shaft bearing hole (141) and sleeved at one end of the driving main shaft (21), and the driven bearing (32) comprises a first driven bearing (321) and a second driven bearing (322); the first driven bearing (321) is positioned in the driven bearing hole (131) and sleeved at one end of the driven main shaft (31), the inner ring of the second driven bearing (322) is sleeved at the other end of the driven main shaft (31), and the outer ring of the second driven bearing (322) is attached to the outer wall of the other end of the driving main shaft (21).

4. The multistage compressor adopting the magnetic planetary rotor shafting for speed increase according to the claim 2, characterized in that a wave spring (221) is arranged between the main shaft bearing (22) and the rear bearing seat (14), and two ends of the wave spring (221) are respectively attached to the outer end surface of the main shaft bearing (22) and the corresponding end surface of the inner side of the rear bearing seat (14); the wave spring (221) is used for pre-tightening the main shaft bearing (22) to prevent the axial movement of the main shaft bearing.

5. The multistage compressor adopting the magnetic planetary rotor shafting for speed increase according to the claim 2, characterized in that the front bearing seat (13) is provided with heat dissipation ribs (132) on the inner end surface, and the heat dissipation ribs (132) are used for dissipating heat inside the casing (1).

6. The multistage compressor adopting the magnetic planetary rotor shafting for speed increase is characterized in that the carbon fiber sheath (331) is fixedly sleeved on the outer wall of the driven magnetic steel (33) of the driven main shaft (31), and the carbon fiber sheath (331) is used for preventing the driven magnetic steel (33) from being damaged.

7. The multistage compressor adopting the magnetic planetary rotor shafting for speed increase according to the claim 2, characterized in that the outside of the rear bearing seat (14) is fixedly provided with a heat dissipation base (5), the inner side end surface of the heat dissipation base (5) is fixedly provided with a heat dissipation fan (51), and the heat dissipation fan (51) is used for dissipating heat inside the casing (1).

8. The multistage compressor for increasing the speed by adopting the magnetic planetary rotor shafting according to the claim 1 is characterized in that the casing (1) is provided with a wind guide part (15), the wind guide part (15) is provided with an upper wind guide surface (151) on the radial outer side surface, and the wind guide part (15) is provided with a lower wind guide surface (152) on the radial inner side surface; the upper air guide surface (151) and the lower air guide surface (152) are used for guiding cooling air in the shell (1) and improving the flowing efficiency of the cooling air.

9. The multistage compressor adopting the magnetic planetary rotor shafting for speed increase according to any one of the claims 2, 7 or 8, characterized in that the heat dissipation base (5) is provided with a first channel (61) which axially penetrates and is communicated with the outside, and the rear bearing seat (14) is provided with a plurality of second channels (62) which axially penetrate; the driving main shaft (21) is provided with an axial third channel (63) and a radial through fourth channel (64), and the motor barrel (12) is provided with a radial through fifth channel (65) and a radial through sixth channel (66); the first channel (61), the second channel (62), the gap between the motor rotor (23) and the motor stator (11) and the fifth channel (65) are communicated with each other to form a first heat dissipation channel, and the upper air guide surface (151) is located between the gap between the motor rotor (23) and the motor stator (11) and the fifth channel (65); the first channel (61), the second channel (62), a gap between the motor rotor (23) and the motor stator (11), a gap between the driven shaft system (3) and the lower air guide surface (152) and the sixth channel (66) are communicated with each other to form a second heat dissipation channel; the first channel (61), the third channel (63), the fourth channel (64) and the sixth channel (66) are communicated with each other to form a third heat dissipation channel.

10. A multistage compressor using magnetic planetary rotor shafting for speed increase according to claim 9, characterized in that the plurality of second passages (62) are distributed along the circumferential direction.

Technical Field

The invention relates to the field of multistage compressors, in particular to a multistage compressor adopting a magnetic planetary rotor shaft system for increasing speed.

Background

The multistage compressor refers to a compressor which increases the gas pressure step by step. Industrial gases sometimes require higher pressures and require multi-stage compression to increase the pressure of the gas in stages. As the required pressure increases, the number of stages of the compressor increases. The multistage compressor is widely applied to the aspects of petrochemical industry, synthetic ammonia, urea, air separation, refrigeration engineering and the like.

The Chinese invention patent application (publication No. CN104421188A, published: 20150318) discloses a multistage centrifugal compressor and an air conditioning unit, wherein the multistage centrifugal compressor comprises a power part and an impeller part, the power part comprises a motor, and a shaft of the motor comprises a first end of the shaft and a second end of the shaft; the impeller part comprises N impellers, and N is more than or equal to 2 and less than 10; when N is a double number, the number of the impellers on the first end of the shaft is equal to that of the impellers on the second end of the shaft; when N is singular, the number of impellers on the first end of the shaft is one more than that on the second end of the shaft; the first-stage impeller is arranged on the first end of the shaft and is farthest away from the motor; the other impellers on the first end of the shaft are sequentially arranged in an ascending order; the Nth-stage impeller is arranged at the second end of the shaft and is closest to the motor; the other impellers on the second end of the shaft are sequentially arranged in a descending order; the air outlet of the first end impeller of the shaft is communicated with the air inlet of the second end impeller of the shaft through a connecting pipeline, so that the purposes of improving the pressure ratio and the energy efficiency are achieved.

The prior art has the following defects: the traditional multistage compressor adopts two methods of increasing speed by a gear box or directly driving a high-speed motor to simultaneously drive multistage impellers; when the gearbox is adopted for increasing speed, the gearbox device is required to be added to the compressor, so that the volume of the whole equipment is increased; meanwhile, oil is used for lubricating and cooling the gear box regularly, and the process of maintaining equipment is increased. When the high-speed motor is adopted for direct drive, the high-speed motor drives the motor shaft to rotate so as to drive the impellers at the two ends of the motor shaft to rotate; in the mode, the distance between the impellers at the two ends of the motor shaft is longer, and the structure is unstable and easy to generate resonance when the motor shaft rotates at a high speed, so that the critical rotating speed of the motor shaft is reduced; meanwhile, when the high-speed motor is directly driven, a plurality of impellers with larger total weight need to be driven at the same time, namely, the load which needs to be driven by the high-speed motor is larger, resonance is easier to generate, and the critical rotating speed of a motor shaft is further reduced; therefore, when the high-speed motor is directly driven, the critical rotating speed of the motor shaft is low, the size of the compressed part of the impeller is large, and the compression ratio of the whole equipment is reduced.

Disclosure of Invention

The purpose of the invention is: aiming at the problems, the driving magnetic steel and the driven magnetic steel are respectively arranged on the driving main shaft and the driven main shaft, and the driving main shaft is used for driving a plurality of driven main shafts simultaneously, so that a gear box device is not required to be arranged, and the volume of the whole equipment is reduced; meanwhile, only one impeller with light weight is arranged on each driven main shaft, and only one impeller is fixed by the shorter driven main shaft; therefore, the critical rotating speed of the driven main shaft is improved, the volume of the compression part of the impeller is reduced, and the compression ratio of the whole device is improved.

In order to achieve the purpose, the invention adopts the following technical scheme:

a multi-stage compressor adopting a magnetic planetary rotor shaft system for increasing speed comprises a shell, a driving shaft system, a plurality of driven shaft systems and a volute, wherein a motor stator is fixedly embedded in an inner hole of the shell; the driving shaft system comprises a driving main shaft, a main shaft bearing, a motor rotor and driving magnetic steel, wherein the motor rotor corresponds to the motor stator in position; the plurality of driving magnetic steels are fixedly arranged on the driving main shaft along the circumferential direction, and the N poles and the S poles of the adjacent driving magnetic steels are arranged in opposite directions in the radial direction; the driven shaft system comprises driven main shafts, driven bearings, driven magnetic steel and impellers, and the driven main shafts of the driven shaft systems are distributed on the outer side of the driving main shaft along the circumferential direction; the plurality of driven magnetic steels are fixedly arranged on the driven main shaft along the circumferential direction, and the N poles and the S poles of the adjacent driven magnetic steels are arranged in opposite directions in the radial direction; the positions of the driven magnetic steels correspond to the positions of the driving magnetic steels, and the ratio of the number of the driving magnetic steels to the number of the driven magnetic steels of different driven shafts is the same as the speed increasing ratio of the driving main shaft to the corresponding driven shaft; the impeller is fixed at one end of the driven main shaft, and the impellers of the plurality of driven shaft systems are respectively positioned in the corresponding compression passages of the volute.

Preferably, the casing comprises a motor barrel, a front bearing seat and a rear bearing seat, the front bearing seat and the rear bearing seat are respectively fixed at two ends of the motor barrel, and the motor stator is fixedly embedded in a corresponding inner hole of the motor barrel.

Preferably, the front bearing seat is provided with a plurality of driven bearing holes, and the rear bearing seat is provided with a driving bearing hole; the main shaft bearing is positioned in the driving shaft bearing hole and sleeved at one end of the driving main shaft, and the driven shaft bearing comprises a first driven bearing and a second driven bearing; the first driven bearing is positioned in the driven bearing hole and sleeved at one end of the driven main shaft, the inner ring of the second driven bearing is sleeved at the other end of the driven main shaft, and the outer ring of the second driven bearing is attached to the outer wall of the other end of the driving main shaft.

Preferably, a wave spring is arranged between the main shaft bearing and the rear bearing seat, and two ends of the wave spring are respectively attached to the end surface of the outer side of the main shaft bearing and the corresponding end surface of the inner side of the rear bearing seat; the wave spring is used for pre-tightening the main shaft bearing to prevent the main shaft bearing from axially moving.

Preferably, the front bearing seat is provided with a heat dissipation rib on the inner side end face, and the heat dissipation rib is used for dissipating heat inside the casing.

Preferably, the fixed cover of driven magnet steel outer wall of driven main shaft is equipped with the carbon fiber sheath, and the carbon fiber sheath is used for preventing that driven magnet steel from receiving the damage.

Preferably, a heat dissipation base is fixedly arranged on the outer side of the rear bearing seat, a heat dissipation fan is fixedly arranged on the end face of the inner side of the heat dissipation base, and the heat dissipation fan is used for dissipating heat inside the casing.

Preferably, the casing is provided with an air guide part, an upper air guide surface is arranged on the radial outer side surface of the air guide part, and a lower air guide surface is arranged on the radial inner side surface of the air guide part; the upper air guide surface and the lower air guide surface are used for guiding the cooling air in the shell, so that the flowing efficiency of the cooling air is improved.

Preferably, the heat dissipation base is provided with a first channel which axially penetrates through the heat dissipation base and is communicated with the outside, and the rear bearing seat is provided with a plurality of second channels which axially penetrate through the rear bearing seat; the driving main shaft is provided with an axial third channel and a radial through fourth channel, and the motor cylinder is provided with a radial through fifth channel and a radial through sixth channel; the first channel, the second channel, the gap between the motor rotor and the motor stator and the fifth channel are communicated with each other to form a first heat dissipation channel, and the upper air guide surface is positioned between the gap between the motor rotor and the motor stator and the fifth channel; the first channel, the second channel, a gap between the motor rotor and the motor stator, a gap between the driven shaft system and the lower air guide surface and the sixth channel are communicated with each other to form a second heat dissipation channel; the first channel, the third channel, the fourth channel and the sixth channel are communicated with each other to form a third heat dissipation channel.

Preferably, the plurality of second passages are distributed along the circumferential direction.

The multistage compressor adopting the technical scheme has the advantages that:

when the motor works, the motor stator is electrified to drive the motor rotor to rotate so as to drive the driving main shaft to rotate; the driving magnetic steel rotates along with the driving main shaft and drives the driven main shafts of the driven shaft systems to rotate simultaneously by driving the driven magnetic steel of the driven shaft systems; the impellers of the driven shafting rotate simultaneously to perform multi-stage compression on the fluid to be compressed to complete the working process. In this way, compared with the gear box speed increasing: the driving magnetic steel on the driving main shaft drives the driven main shafts of the driven shaft systems simultaneously through magnetic force, namely, the driven shaft systems can be driven without arranging a gear box, and the size of the whole equipment is reduced; and when the magnetic drive is adopted, oil is not needed to lubricate the magnetic drive, so that the process of maintaining equipment is reduced. Compared with direct drive of a high-speed motor: only one impeller needs to be fixed on each driven main shaft, namely the driven main shaft only needs a short length to drive the impeller to rotate; the driven main shaft with a short length is stable in structure and is not easy to resonate when rotating at a high speed, so that the critical rotating speed of the driven main shaft is improved; moreover, when each driven spindle only drives one impeller with light total weight, the load is small, and the driven spindle is not easy to generate resonance when rotating at high speed; therefore, the critical rotating speed of the driven main shaft is further improved, the volume of the compression part of the impeller is further reduced, and the compression ratio of the whole equipment is improved.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 and 3 are schematic structural views of the front bearing seat.

Fig. 4 is a schematic structural view of a multi-stage compressor rotor system.

Fig. 5 and fig. 6 are schematic structural diagrams of a section a-a and a section B-B of the rotor system, respectively.

Fig. 7 is a schematic structural view of the impeller.

Fig. 8 is a schematic structural view of a motor cartridge.

Fig. 9 and 10 are schematic structural views of the rear bearing.

Fig. 11 and 12 are schematic structural diagrams of a volute.

Fig. 13 is a schematic structural diagram of the first heat dissipation channel, the second heat dissipation channel, and the third heat dissipation channel.

Detailed Description

The following describes in detail embodiments of the present invention with reference to the drawings.

Example 1

As shown in fig. 1, the multistage compressor adopting the magnetic planetary rotor shafting for speed increase comprises a casing 1, a driving shafting 2, a plurality of driven shafting 3 and a volute 4, wherein a motor stator 11 is fixedly embedded in an inner hole of the casing 1; the driving shaft system 2 comprises a driving main shaft 21, a main shaft bearing 22, a motor rotor 23 and driving magnetic steel 24, wherein the position of the motor rotor 23 corresponds to that of the motor stator 11; the plurality of driving magnetic steels 24 are fixedly arranged on the driving spindle 21 along the circumferential direction, and the N poles and the S poles of the adjacent driving magnetic steels 24 are arranged in opposite directions in the radial direction; the driven shaft system 3 comprises a driven main shaft 31, a driven bearing 32, driven magnetic steel 33 and an impeller 34, and the driven main shafts 31 of the driven shaft systems 3 are distributed outside the driving main shaft 21 along the circumferential direction; a plurality of driven magnetic steels 33 are fixedly arranged on the driven main shaft 31 along the circumferential direction, and the N pole and the S pole of the adjacent driven magnetic steels 33 are arranged in the opposite directions in the radial direction; the positions of the driven magnetic steels 33 correspond to the positions of the driving magnetic steels 24, and the ratio of the number of the driving magnetic steels 24 to the number of the driven magnetic steels 33 of different driven shafts 3 is the same as the speed increasing ratio of the driving main shaft 21 to the corresponding driven shaft 3; the impellers 34 are fixed at one end of the driven main shaft 31, and the impellers 34 of the plurality of driven shaft systems 3 are respectively positioned in the corresponding compression passages of the volute 4. When the electric vehicle works, the motor stator 11 is electrified to drive the motor rotor 23 to rotate so as to drive the driving main shaft 21 to rotate; the driving magnetic steel 24 rotates along with the driving main shaft 21 and drives the driven main shafts 31 of the driven shaft systems 3 to rotate simultaneously through the driven magnetic steel 33 driving the driven shaft systems 3; the impellers 34 of the driven shafting 3 rotate simultaneously to perform multi-stage compression on the fluid to be compressed, and the working process is completed. In this way, compared with the gear box speed increasing: the driving magnetic steel 24 on the driving main shaft 21 drives the driven main shafts 31 of the plurality of driven shaft systems 3 simultaneously through magnetic force, namely, the plurality of driven shaft systems 3 can be driven without arranging a gear box, and the size of the whole equipment is reduced; and when the magnetic drive is adopted, oil is not needed to lubricate the magnetic drive, so that the process of maintaining equipment is reduced. Compared with direct drive of a high-speed motor: only one impeller 34 needs to be fixed on each driven main shaft 31, namely, the driven main shaft 31 only needs a short length to drive the impeller 34 to rotate; the driven main shaft 31 with a short length is stable in structure and is not easy to resonate when rotating at a high speed, so that the critical rotating speed of the driven main shaft 31 is improved; moreover, when each driven main shaft 31 only drives one impeller 34 with light total weight, the load is small, and resonance is not easy to generate when the driven main shaft 31 rotates at high speed; therefore, the critical rotating speed of the driven main shaft 31 is further improved, the volume of the compression part of the impeller is further reduced, and the compression ratio of the whole equipment is improved.

The casing 1 comprises a motor barrel 12, a front bearing seat 13 and a rear bearing seat 14, wherein the front bearing seat 13 and the rear bearing seat 14 are respectively fixed at two ends of the motor barrel 12, and the motor stator 11 is fixedly embedded in a corresponding inner hole of the motor barrel 12.

The front bearing block 13 is provided with a plurality of driven bearing holes 131, and the rear bearing block 14 is provided with a driving bearing hole 141; the main shaft bearing 22 is positioned in the main shaft bearing hole 141 and is sleeved at one end of the driving main shaft 21, and the driven bearing 32 comprises a first driven bearing 321 and a second driven bearing 322; the first driven bearing 321 is located in the driven bearing hole 131 and is sleeved at one end of the driven main shaft 31, the inner ring of the second driven bearing 322 is sleeved at the other end of the driven main shaft 31, and the outer ring of the second driven bearing 322 is attached to the outer wall of the other end of the driving main shaft 21. The main shaft bearing 22 and the first driven bearing 321 respectively support the outside of the driving main shaft 21 and the outside of the driven main shaft 31 in a hard manner, and the second driven bearing 322 supports the inside of the driving main shaft 21 and the inside of the driven main shaft 31 in a soft manner so as to support the driving main shaft 21 and the driven main shaft 31 at the same time.

A wave spring 221 is arranged between the main shaft bearing 22 and the rear bearing seat 14, and two ends of the wave spring 221 are respectively attached to the end surface of the outer side of the main shaft bearing 22 and the corresponding end surface of the inner side of the rear bearing seat 14; the wave spring 221 is used to pre-tension the main shaft bearing 22 to prevent axial play.

As shown in fig. 3, the front bearing housing 13 is provided with a heat dissipating rib 132 on an inner end surface, and the heat dissipating rib 132 is used for dissipating heat inside the casing 1.

As shown in fig. 1, a carbon fiber sheath 331 is fixedly sleeved on an outer wall of the driven magnetic steel 33 of the driven spindle 31, and the carbon fiber sheath 331 is used for preventing the driven magnetic steel 33 from being damaged.

The outer side of the rear bearing seat 14 is fixedly provided with a heat dissipation base 5, the inner side end face of the heat dissipation base 5 is fixedly provided with a heat dissipation fan 51, and the heat dissipation fan 51 is used for dissipating heat inside the casing 1.

As shown in fig. 8, the casing 1 is provided with an air guiding portion 15, the air guiding portion 15 is provided with an upper air guiding surface 151 on the radial outer side surface, and the air guiding portion 15 is provided with a lower air guiding surface 152 on the radial inner side surface; the upper and lower air guide surfaces 151 and 152 guide the cooling air inside the cabinet 1, thereby improving the flow efficiency.

As shown in fig. 13, the heat-dissipating base 5 is provided with a first passage 61 that axially penetrates and communicates with the outside, and the rear bearing housing 14 is provided with a plurality of second passages 62 that axially penetrate; the driving main shaft 21 is provided with an axial third channel 63 and a radial through fourth channel 64, and the motor barrel 12 is provided with a radial through fifth channel 65 and a radial through sixth channel 66; the first channel 61, the second channel 62, the gap between the motor rotor 23 and the motor stator 11, and the fifth channel 65 are communicated with each other to form a first heat dissipation channel, and the upper wind guide surface 151 is located between the gap between the motor rotor 23 and the motor stator 11 and the fifth channel 65; the first channel 61, the second channel 62, the gap between the motor rotor 23 and the motor stator 11, the gap between the driven shaft system 3 and the lower air guide surface 152 and the sixth channel 66 are communicated with each other to form a second heat dissipation channel; the first channel 61, the third channel 63, the fourth channel 64 and the sixth channel 66 are communicated with each other to form a third heat dissipation channel. The plurality of second passages 62 are distributed along the circumferential direction.