JP5182520B2 - Centrifugal compressor - Google Patents

Description

  The present invention relates to a centrifugal compressor used in a supercharger, a gas turbine, an industrial air facility, or the like.

  In recent years, various developments have been made on centrifugal compressors used in superchargers such as a supercharger for vehicles, and Patent Literature 1 and Patent Literature as a centrifugal compressor (general centrifugal compressor) according to the prior art. There are those shown in 2 etc. The configuration of the centrifugal compressor according to the prior art will be described as follows.

  That is, the centrifugal compressor according to the prior art includes a housing, and the housing has a shroud inside. Further, an impeller is rotatably provided in the shroud of the housing, and the impeller has a hub that can rotate about an axis (an axis of the impeller, in other words, an axis of the housing), and the hub. Are provided with a plurality of blades provided on the outer peripheral surface thereof at intervals in the circumferential direction. Here, the outer edge of each blade extends along the shroud of the housing. The hub is integrally connected to one end of the rotor shaft in the supercharger.

  A suction port for sucking air (an example of gas) to the impeller side is formed at the upstream peripheral edge (impeller inlet side) of the shroud of the housing. Further, an exhaust passage for exhausting compressed high-pressure air (an example of high-pressure gas) is formed at the downstream peripheral edge (impeller outlet side) of the shroud of the housing.

  Therefore, by rotating the rotor shaft and integrally rotating the impeller, air can be sucked from the suction port toward the impeller and compressed. The compressed high-pressure air is exhausted from the exhaust passage.

JP 11-30199 A JP 2003-65298 A

  By the way, due to restrictions on mounting the centrifugal compressor, a bent duct having a curved portion (bent portion) in the housing may be disposed so as to communicate with the suction port. In recent years, the bending portion of the bent duct tends to be closer to the impeller in order to increase the degree of freedom of mounting the centrifugal compressor. On the other hand, if the curved part of the bent duct is close to the impeller, not only energy loss occurs due to separation of air flow inside the inner wall surface of the bent part of the bent duct, but turbulent flow air flows into the impeller side. Thus, the performance (compressor efficiency) of the centrifugal compressor is reduced.

  That is, there is a problem that it is difficult to improve the performance of the centrifugal compressor while increasing the degree of freedom of mounting the centrifugal compressor.

  Then, an object of this invention is to provide the centrifugal compressor of a novel structure which can solve the above-mentioned problem.

  The present invention is characterized in that, in a centrifugal compressor that compresses gas using centrifugal force, a housing having a shroud on the inside thereof, and a rotatable inside the shroud of the housing are rotatable around an axis. A hub, and an impeller provided with a plurality of blades provided on the outer peripheral surface of the hub at intervals in the circumferential direction and having an outer edge extending along the shroud of the housing. A suction port for sucking gas into the impeller side is formed at the upstream peripheral edge (the impeller inlet side) of the shroud, and the compressed high-pressure gas is exhausted to the downstream peripheral edge (the impeller outlet side) of the shroud of the housing. An exhaust passage is formed, and a bent duct having a curved portion (bent portion) is disposed in the housing so as to communicate with the suction port. Ri can be summarized as that the rectifying grooves extending toward the impeller side the the inner wall surface inside of the curved portion (the inner wall surface corner inside) of the duct is formed.

  In the claims and the description, the “upstream side” means the upstream side when viewed from the mainstream flow direction, and the “downstream side” means the downstream side when viewed from the mainstream flow direction. That is. The “inner wall surface inside” refers to a side having a small curvature radius on the inner wall surface of the curved portion of the bent duct. Further, the bent duct may be formed integrally with the housing, may be formed separately from the housing, and the number of the rectifying grooves may be one, There may be more than one.

  Therefore, by rotating the impeller integrally, gas can be sucked into the impeller side through the bent duct and compressed. The compressed high-pressure gas is exhausted from the exhaust passage.

  Here, since the rectifying groove extending toward the impeller side is formed on the inner wall surface of the curved portion of the bent duct, the rectifying groove has a pressure difference between the upstream side and the downstream side in the rectifying groove. The gas flow in the direction intersecting the main flow direction is regulated by the both side walls of the rectifying groove while promoting the gas flow of the gas flow, and the gas flow in the vicinity of the inner wall surface of the curved portion of the bent duct is controlled. The flow can be rectified.

  According to the present invention, it is possible to rectify the gas flow in the vicinity of the inner wall surface of the curved portion of the bent duct while promoting the flow of gas in the rectifying groove, so that the curved portion of the bent duct is connected to the impeller. Even if it approaches, the separation of the gas flow on the inner wall surface of the curved portion of the bent duct can be suppressed, and the gas flow on the inlet side of the impeller can be stabilized. Thereby, the improvement of the performance of the said centrifugal compressor can be aimed at, raising the mounting freedom degree of the said centrifugal compressor.

It is a sectional side view of the centrifugal compressor concerning the embodiment of the present invention, and is a sectional view which passes along the axis of the impeller in the direction along the bending direction of the bending portion of the bending duct. It is a partial expanded sectional view of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, and is a cross-sectional view orthogonal to the direction along the bending direction of the bending portion of the bending duct and passing through the impeller axis. It is sectional drawing along the IV-IV line in FIG.

  An embodiment of the present invention will be described with reference to FIGS. In the drawings, “F” indicates the forward direction, and “R” indicates the backward direction.

  As shown in FIGS. 1 and 2, a centrifugal compressor 1 according to an embodiment of the present invention is used for a supercharger such as a supercharger for a vehicle, and uses air (an example of gas) using centrifugal force. Compress. And the specific structure of the centrifugal compressor 1 which concerns on embodiment of this invention is as follows.

  The centrifugal compressor 1 includes a housing (compressor housing) 3. The housing 3 includes a housing body 5 having a shroud 5S inside, and a mounting plate (seal plate) provided on the rear side of the housing body 5. ) 7 etc. The mounting plate 7 is integrally connected to another housing (bearing housing) 9 in the supercharger.

  An impeller 11 is rotatably provided in the shroud 5S of the housing body 5. Specifically, a hub 13 is provided in the shroud 5S of the housing body 5, and the outer peripheral surface of the hub 13 is radially outward from the axial direction of the hub 13 (in other words, the shaft of the impeller 11). It extends from the central direction toward the radially outer side. The hub 13 is integrally connected to one end portion (front end portion) of a rotor shaft (turbine shaft) 15 rotatably provided in another housing 9 via a fixing nut 17. It can rotate around the axis (in other words, the axis of the impeller 11). Further, a plurality of long blades (full blades) 19 and a plurality of short blades (splitter blades) 21 are alternately provided on the outer peripheral surface of the hub 13 at intervals in the circumferential direction. Here, the front edge of the long blade 19 is located on the upstream side (front side) of the front edge of the short blade 21, and the outer edge of each long blade 19 and the outer edge of each short blade 21 are located on the housing body 5. It extends along the shroud 5S. Instead of using two types of blades 19 and 21 having different axial lengths, blades having the same axial length may be used.

  A suction port 23 for sucking air into the impeller 11 is formed in the front side portion of the housing body 5. Further, an annular diffuser passage 25 (an example of an exhaust passage) that decelerates and exhausts compressed high-pressure air (an example of high-pressure gas) at a downstream peripheral edge (an outlet side of the impeller 11) of the shroud 5S of the housing body 5. ) And a spiral scroll channel 27 (an example of an exhaust channel) is formed on the peripheral side of the diffuser channel 25 inside the housing body 5. Furthermore, a discharge port (not shown) for discharging air is formed at an appropriate position of the housing body 5, and this discharge port communicates with the diffuser flow channel 25 via the scroll flow channel 27. It can be connected to an intake manifold (not shown) of the internal combustion engine.

  Then, the principal part of embodiment of this invention is demonstrated.

  As shown in FIGS. 2, 3, 4 (a) and 4 (b), a bent duct 29 is disposed on the front side of the housing body 5 so as to communicate with the suction port 23. The bent portion 29 has a curved portion (bent portion) 31 and the distal end portion of the bent duct 29 can be connected to an air cleaner (not shown). Here, the inner wall surface inner side (inner wall surface corner inner side) 31W of the curved portion 31 of the bent duct 29 is a side having a smaller radius of curvature on the inner wall surface of the curved portion 31 of the bent duct 29, and the bending start region 31Wa. A curved intermediate region 31Wb that is continuous to the curvature start region 31Wa and has a radius of curvature smaller than the curvature radius of the curvature start region 31Wa, and a curvature radius that is continuous to the curved intermediate region 31Wb and has a curvature radius that is larger than the curvature radius of the curvature intermediate region 31Wb. And a large curve end region 31Wc. In the embodiment of the present invention, the bent duct 29 is integrally formed with the housing body 5, but may be formed separately from the housing body 5.

  A plurality of rectifying grooves 33 extending toward the impeller 11 are formed on the inner wall surface 31 </ b> W of the curved portion 31 of the housing body 5. Here, the number of the rectifying grooves 33 is not limited to five shown in FIGS. 3 and 4A, and may be ten or more or one as shown in FIG. 4B. . Further, the upstream end (upstream end) of each rectifying groove 33 is located in the vicinity of the downstream side of the upstream end of the inner wall surface 31 </ b> W (upstream end of the bending start region 31 </ b> Wa) in the curved portion 31 of the bending duct 29. Thus, the groove depth near the upstream end of each rectifying groove 33 is gradually shallower toward the upstream side. Further, the downstream end (downstream end) of each rectifying groove 33 reaches the vicinity of the inlet side of the impeller 11, and the groove depth near the downstream end of each rectifying groove 33 gradually decreases toward the downstream side. It is shallow. Even if the downstream end of each rectifying groove 33 does not reach the vicinity of the inlet side of the impeller 11, the downstream side of the inner wall surface inner side 31W (the downstream end of the bending end region 31Wc) in the curved portion 31 of the bent duct 29. It does not matter if it is located in.

  When viewed from a cross-section (predetermined cross-section) orthogonal to the direction along the bending direction (bending direction) of the bending portion 31 of the bending duct 29 and passing through the axis C of the impeller 11, each rectifying groove 33 is formed on the impeller 11. It is parallel to the axis C. Further, when viewed from the predetermined cross section, at least one of the plurality of rectifying grooves 33 among all the rectifying grooves 33 is arranged to approach the axis C side of the impeller 11. Further, when viewed from the predetermined cross section, the central rectifying groove 33 overlaps the axis C of the impeller 11. When viewed from the predetermined cross section, the state where the rectifying groove 33 overlaps the axis C of the impeller 11 is also a state parallel to the axis of the impeller 11 and close to the axis C of the impeller 11. .

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  By rotating the rotor shaft 15 and rotating the impeller 11 integrally, air can be sucked into the impeller 11 side through the bent duct 29 and compressed. The compressed high-pressure air is exhausted from the diffuser flow path 25 and the scroll flow path 27 and sent to the intake manifold of the internal combustion engine via the discharge port.

  Here, since a plurality of rectifying grooves 33 extending toward the impeller 11 are formed on the inner wall surface 31 </ b> W of the curved portion 31 of the bending duct 29, the pressure difference between the upstream side and the downstream side in each rectifying groove 33. The flow of air in each rectifying groove 33 is promoted by the above, while the flow of air in the direction intersecting the mainstream flow direction is regulated by the both side walls of each rectifying groove 33, The air flow in the vicinity of the inner wall surface 31W can be rectified. In particular, when viewed from the predetermined cross section, each rectifying groove 33 is parallel to the axis C of the impeller 11, and at least one of the rectifying grooves 33 among all the rectifying grooves 33 is the impeller. 11, the rectifying action in the vicinity of the inner wall surface 31W of the curved portion 31 of the bent duct 29 can be sufficiently exerted.

  Therefore, according to the embodiment of the present invention, the air flow in the vicinity of the inner wall surface 31 </ b> W of the curved portion 31 of the bent duct 29 can be rectified while promoting the air flow in each rectifying groove 33. Even when the curved portion 31 is brought closer to the impeller 11, separation of the air flow on the inner wall surface 31 </ b> W of the curved portion 31 of the bent duct 29 can be suppressed, and the air flow on the inlet side of the impeller 11 can be stabilized. In particular, since the downstream end of each rectifying groove 33 reaches the vicinity of the inlet side of the impeller 11, the air flow on the inlet side of the impeller 11 can be sufficiently stabilized. Therefore, it is possible to improve the performance (compressor efficiency) of the centrifugal compressor 1 while increasing the degree of freedom of mounting the centrifugal compressor 1.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

DESCRIPTION OF SYMBOLS 1 Centrifugal compressor 3 Housing 5 Housing main body 5S Shroud 7 Mounting plate 11 Impeller 13 Hub 19 Long blade 21 Short blade 23 Suction port 25 Diffuser flow path 27 Scroll flow path 29 Curved duct 31 Curved part 31W Inner wall inner surface 31Wa Curve start area 31Wb Curvature middle region 31Wc Curvature end region 33 Rectification groove

Claims (5)

In a centrifugal compressor that compresses gas using centrifugal force,
A housing having a shroud inside;
A hub rotatably provided in the shroud of the housing and rotatable about an axis, and a circumferentially spaced outer peripheral surface of the hub and having an outer edge along the shroud of the housing An impeller having a plurality of extended blades, and
An inlet for sucking gas to the impeller side is formed at the upstream peripheral edge of the shroud of the housing, and an exhaust passage for exhausting compressed high-pressure gas is formed at the downstream peripheral edge of the shroud of the housing,
A bent duct having a curved portion in the housing is disposed so as to communicate with the suction port, and a rectifying groove extending toward the impeller side is formed on the inner wall surface of the curved portion of the bent duct. Centrifugal compressor characterized by.   The centrifugal compressor according to claim 1, wherein a downstream end of the rectifying groove reaches a vicinity of an inlet side of the impeller.   The straightening groove is parallel to the axis of the impeller when viewed from a cross section orthogonal to the direction along the bending direction of the bending portion of the bending duct and passing through the axis of the impeller. The centrifugal compressor according to claim 1 or 2.   The number of the rectifying grooves is plural, and when viewed from a cross section orthogonal to the direction along the bending direction of the bending portion of the bent duct and passing through the axis of the impeller, at least one of the rectifying grooves The centrifugal compressor according to any one of claims 1 to 3, wherein is close to an axial center side of the impeller.   The upstream end of the rectifying groove is located in the vicinity of the downstream side of the upstream end on the inner wall surface of the curved portion of the bent duct, according to any one of claims 1 to 4. The centrifugal compressor described in 1.

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