JP6865604B2 - Centrifugal compressor and exhaust turbine supercharger - Google Patents

Description

The present invention relates to a centrifugal compressor and an exhaust turbine supercharger.

For example, a centrifugal compressor of a turbocharger for power generation and marine engines is required to have a wide operating range in a high pressure ratio region due to an increase in engine output in recent years. As one of the devices for expanding the operating range, a casing treatment that provides a circulation flow path is known (see, for example, Patent Document 1). The circulation flow path can suppress the stall of the impeller and expand the operating range by recirculating the air in the operating state where the flow rate is small. By improving the shape like this, the effect of expanding the operating range is improved. Patent Document 1 discloses a configuration in which the width of the extraction groove (suction ring groove) of the recirculation path is changed in the circumferential direction as a non-axisymmetric casing treatment.

Japanese Patent No. 5430684

In general casing treatments, there are many configurations in which a circulation flow path is provided in an axisymmetric shape in the circumferential direction. However, since the scroll passage of the casing is configured to be non-axisymmetric with respect to the rotation axis of the impeller, the flow is distorted due to the non-axis symmetry of the scroll passage at a small flow rate outside the design range, and the scroll tongue portion. Although the reverse pressure gradient increases in the vicinity, the above strain of the pressure gradient is not taken into consideration in the casing treatment provided with the axisymmetric circulation flow path in the circumferential direction. When the conventional casing treatment is applied, the pressure ratio of the impeller increases and stall is suppressed, but the radial dynamic pressure at the impeller outlet decreases, so the vicinity of the tongue where the reverse pressure gradient becomes steep as described above. In this case, local stall and backflow are likely to occur, and as a result, there is a risk that the effect of expanding the operating range cannot be obtained.

An object of the present invention is to solve the above-mentioned problems, and to provide a centrifugal compressor and an exhaust turbine supercharger capable of suppressing local stall and backflow in the vicinity of the tongue of a scroll passage. ..

The centrifugal compressor according to one aspect of the present invention is provided with a rotating shaft, an impeller attached to the rotating shaft and having a plurality of blades radially, and air intake along the extending axial direction of the rotating shaft. An air supply passage from the inlet to the impeller, a compression passage formed in a ring shape along the outer peripheral portion of the impeller, a spiral-shaped scroll passage communicating with the outer circumference of the compression passage, and a part of the scroll passage. A housing having an exhaust passage branching in a tangential direction from the rotating shaft and accommodating the impeller, and a space formed in a ring shape outside the air supply passage in the housing and supplying the impeller on the impeller side. A recirculation passage having an annular bleeding groove that opens in the air passage and an annular recirculation groove that opens in the air supply passage on the air intake side, and a space inside the recirculation passage in the annular direction. A plurality of struts extending along the axial direction so as to be partitioned by the above, and the struts at an angle position about the rotation axis of the tongue portion where the exhaust passage branches from the scroll passage. The cross-sectional area of the space partitioned by is reduced from the bleeding groove toward the recirculation groove.

Further, in the centrifugal compressor according to one aspect of the present invention, the radial width in the space formed by the cross-sectional area decreasing from the bleed groove toward the recirculation groove is increased from the bleed groove to the recirculation groove. It is preferable that it is formed so as to shrink toward it.

Further, in the centrifugal compressor according to one aspect of the present invention, a part of the groove width of the bleeding groove is formed narrow in the space formed by the cross-sectional area decreasing from the bleeding groove toward the recirculation groove. It is preferable to have.

Further, in the centrifugal compressor according to one aspect of the present invention, a shutter that opens and closes a part of the groove width of the bleeding groove in the space formed by the cross-sectional area decreasing from the bleeding groove toward the recirculation groove. It is preferable to provide an operating mechanism that closes the shutter when the pressure rises and opens the shutter when the pressure drops based on the pressure in the exhaust passage.

The exhaust turbine turbocharger according to one aspect of the present invention has the centrifugal compressor according to any one of the above.

In a general casing treatment, a part of the compressed air pressurized by the impeller is drawn from the bleed groove into the recirculation passage and returned from the recirculation groove to the air supply passage to be recirculated. Therefore, when the flow rate of the sucked air is small, the operating flow rate is increased by recirculation to suppress stall, and the pressure ratio of the impeller is increased, so that the operating range of the compressor can be expanded. In addition to the above effects, according to the centrifugal compressor of the present invention, the cross-sectional area of the space of the recirculation passage partitioned by the strut is set at an angle position about the rotation axis of the tongue where the exhaust passage branches from the scroll passage. It is formed by decreasing from the bleeding groove toward the recirculation groove. Therefore, the air recirculated in the recirculation passage is collected at the angular position of the tongue and becomes a large flow rate, and the air compressed by the impeller and discharged to the scroll passage increases the flow rate at the position of the tongue. Increases dynamic pressure. As a result, local stall and backflow near the tongue of the scroll passage can be suppressed. Moreover, according to the present invention, since the circumferential distribution of the air flow rate recirculated and discharged is changed by the area distribution of the recirculation passage instead of the extracted air flow rate, the flow rate extracted by the impeller is the circumferential direction. It is possible to prevent the bleeding flow rate from being extremely increased at a specific circumferential position and the radial dynamic pressure at the impeller outlet at that position from becoming too small. As a result, according to the exhaust turbine supercharger of the present invention, in the centrifugal compressor, it is possible to suppress the local stall and backflow in the vicinity of the tongue of the scroll passage while expanding the stall limit of the impeller. The operating range can be expanded more than the typical casing treatment.

FIG. 1 is an overall configuration diagram of an exhaust turbine turbocharger to which a centrifugal compressor according to an embodiment of the present invention is applied. FIG. 2 is a cross-sectional view of a centrifugal compressor of an exhaust turbine turbocharger to which the centrifugal compressor according to the embodiment of the present invention is applied. FIG. 3 is an axial sectional view of the centrifugal compressor according to the embodiment of the present invention. FIG. 4 is a circumferential cross-sectional development view of the centrifugal compressor according to the embodiment of the present invention. FIG. 5 is a diagram showing a flow rate distribution of a centrifugal compressor according to an embodiment of the present invention. FIG. 6 is an axial sectional view of another example of the centrifugal compressor according to the embodiment of the present invention. FIG. 7 is a circumferential cross-sectional development view of another example of the centrifugal compressor according to the embodiment of the present invention. FIG. 8 is a circumferential cross-sectional development view of another example of the centrifugal compressor according to the embodiment of the present invention. FIG. 9 is an axial sectional view of another example of the centrifugal compressor according to the embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same.

FIG. 1 is an overall configuration diagram of an exhaust turbine turbocharger to which the centrifugal compressor according to the present embodiment is applied. FIG. 2 is a cross-sectional view of a centrifugal compressor of an exhaust turbine supercharger to which the centrifugal compressor according to the present embodiment is applied. FIG. 3 is an axial sectional view of the centrifugal compressor according to the present embodiment. FIG. 4 is a circumferential cross-sectional development view of the centrifugal compressor according to the present embodiment. FIG. 5 is a diagram showing a flow rate distribution of a centrifugal compressor according to an embodiment of the present invention.

The exhaust turbine supercharger 11 shown in FIG. 1 is mainly composed of a turbine 12, a compressor (centrifugal compressor) 13, and a rotating shaft 14, and these are housed in a housing 15.

The housing 15 is formed to be hollow, and has a turbine housing 15A forming a first space portion S1 accommodating the configuration of the turbine 12 and a compressor housing 15B forming a second space portion S2 accommodating the configuration of the compressor 13. It has a bearing housing 15C forming a third space portion S3 for accommodating the shaft 14. The third space portion S3 of the bearing housing 15C is located between the first space portion S1 of the turbine housing 15A and the second space portion S2 of the compressor housing 15B.

The end of the rotary shaft 14 on the turbine 12 side is rotatably supported by the journal bearing 21 which is the turbine side bearing, and the end on the compressor 13 side is rotatably supported by the journal bearing 22 which is the compressor side bearing. The thrust bearing 23 regulates the axial movement of the rotating shaft 14 extending. The center line C of the rotation of the rotation shaft 14 is shown by a chain line in the figure. Further, the turbine wheel 24 of the turbine 12 is fixed to one end of the rotating shaft 14 in the axial direction. The turbine wheel 24 is provided with a plurality of turbine blades 25 having an axial flow type on the outer peripheral portion at intervals in the circumferential direction (the circumferential direction of the rotating shaft 14 about the center line C). The turbine wheel 24 is housed in the first space portion S1 of the turbine housing 15A in the housing 15. Further, the impeller 31 of the compressor 13 is fixed to the other end of the rotating shaft 14 in the axial direction. The impeller 31 is provided with a plurality of blades 32 radially spaced around the center line C of the rotating shaft 14 at intervals in the circumferential direction. The impeller 31 is housed in the second space S2 of the compressor housing 15B in the housing 15.

Further, the turbine housing 15A is provided with an exhaust gas intake port 26 for taking in exhaust gas and an exhaust gas discharge port 27 for discharging exhaust gas to the turbine wheel 24. The turbine housing 15A is provided with a turbine nozzle 28 between the exhaust gas intake port 26 and the turbine wheel 24, and the turbines have a plurality of axial exhaust gas flows that are statically expanded by the turbine nozzle 28. By being guided by the turbine blade 25 of the wheel 24, the turbine 12 can be driven and rotated.

Further, the compressor housing 15B is provided with an air intake port 33 for taking in the compression gas and a compressed air discharge port 34 for discharging the compressed air to the impeller 31. The compressor housing 15B is provided with a diffuser 35 between the impeller 31 and the compressed air discharge port 34. The air compressed by the impeller 31 is discharged through the diffuser 35.

In the compressor housing 15B, the air intake port 33 is formed at the end of the air supply passage 15Ba provided along the extending axial direction of the rotating shaft 14. The air supply passage 15Ba is provided from the air intake port 33 to the impeller 31. Further, in the compressor housing 15B, a compression passage 15Bb formed in a ring shape along the outer peripheral portion of the impeller 31 while communicating with the air supply passage 15Ba is provided. Further, in the compressor housing 15B, as shown in FIGS. 1 and 2, a scroll passage formed in a spiral shape on the outside of the diffuser 35 on the outlet side of the compressed air in the impeller 31 and communicating with the outer periphery of the compression passage 15Bb. 15 Bc is provided. Further, in the compressor housing 15B, an exhaust passage 15Bd that branches in the tangential direction from a part of the scroll passage 15Bc is provided. A compressed air discharge port 34 is formed at the open end of the exhaust passage 15Bd. The scroll passage 15Bc is formed by gradually expanding the inner diameter in the circumferential direction from the winding start having the smallest inner diameter, and is connected to the winding end having one round in the circumferential direction. An exhaust passage 15Bd is branched and provided at the end of winding in which the inner shape is most expanded. In the scroll passage 15Bc, the portion where the exhaust passage 15Bd branches is a portion where the winding start and the winding end are connected as described above, and the tongue portion 15Be protruding inward of the passage is formed. In the compressor 13 having such a configuration, the air taken into the air supply passage 15Ba from the air intake port 33 is compressed by the impeller 31 and is radially from the compression passage 15Bb by the diffuser 35 (perpendicular to the central axis C). The air is diffused to the outside, swirls around the scroll passage 15Bc, and is discharged from the compressed air discharge port 34 of the exhaust passage 15Bd.

Further, in the compressor housing 15B, as shown in FIGS. 1 to 3, a recirculation passage 15Bf is formed in the air supply passage 15Ba. The recirculation passage 15Bf is a space formed in a ring shape on the outside of the air supply passage 15Ba. The recirculation passage 15Bf is a space provided between the inner wall surface of the air supply passage 15Ba and the annular passage wall 36 provided along the inner wall surface of the air supply passage 15Ba, and is provided in the axial direction. The impeller 31 has an annular bleeding groove 36a that opens in the air supply passage 15Ba on the air supply inlet side and an annular recirculation groove 36b that opens in the air supply passage 15Ba on the air intake port 33 side. It is formed on the outside of the passage 15Ba so as to communicate with the impeller 31 side and the air intake port 33 side. Then, in order to secure a space between the inner wall surface of the air supply passage 15Ba and the passage wall 36 to form the recirculation passage 15Bf, the space extends in the axial direction between the inner wall surface of the air supply passage 15Ba and the passage wall 36. A plurality of struts 36c existing and partitioning the space of the recirculation passage 15Bf are provided in the circumferential direction.

In the exhaust turbine supercharger 11 configured in this way, the turbine 12 is driven by the exhaust gas discharged from the engine (not shown), the rotation of the turbine 12 is transmitted to the rotating shaft 14, and the compressor 13 is driven. , The compressor 13 compresses the combustion gas and supplies it to the engine. Specifically, the exhaust gas from the engine passes through the exhaust gas inlet passage 26, is statically expanded by the turbine nozzle 28, and the exhaust gas flow in the axial direction is guided to the plurality of turbine blades 25, whereby a plurality of turbines are used. The turbine 12 is driven and rotated by the turbine wheel 24 to which the blade 25 is fixed. Then, the exhaust gas that drives the plurality of turbine blades 25 is discharged to the outside from the outlet passage 27. On the other hand, when the rotating shaft 14 is rotated by the turbine 12, the impeller 31 of the compressor 13 integrated with the rotating shaft 14 rotates, and air is sucked from the air intake port 33 through the air supply passage 15Ba. The sucked air is pressurized by the impeller 31 to become compressed air, and this compressed air is supplied to the engine from the compressed air discharge port 34 through the diffuser 35 and the scroll passage 15Bc. Further, in the compressor 13, a part of the compressed air pressurized by the impeller 31 is drawn from the bleed air groove 36a into the recirculation passage 15Bf, returned from the recirculation groove 36b to the air supply passage 15Ba, and recirculated. By recirculating the air in the recirculation passage 15Bf in this way, for example, the pressure ratio of the impeller 31 is increased at a small flow rate when the air flow rate sucked at a low speed of the engine is small, and the operating range of the compressor 13 is increased. Expanding.

In the compressor (centrifugal compressor) 13 described above, as shown in FIG. 2, the recirculation passages 15Bf are provided with three struts 36c every 120 deg in the circumferential direction. Then, as shown in FIG. 4, the strut 36c has an angular position (position of 30 deg in FIG. 4) about the rotation axis 14 (center line C) of the tongue portion 15 Be formed in the scroll passage 15 Bc and the tongue. It is provided every 120 deg from the angular position of the portion 15 Be. Then, at least one strut 36c is formed by reducing the cross-sectional area of the space of the recirculation passage 15Bf partitioned by the strut 36c from the bleeding groove 36a toward the recirculation groove 36b at the angular position of the tongue portion 15Be. It is arranged so as to. Specifically, as shown in FIG. 4, in the strut 36c at the angular position of 150 deg adjacent to the strut 36c at the angular position of the tongue portion 15 Be in the circumferential direction, the recirculation groove 36b side is the angular position of the tongue portion 15 Be. It is arranged at an angle toward (30 deg position).

Further, although not explicitly shown in the drawing, the strut 36c at an angular position of 150 deg may be formed by bending the recirculation groove 36b side toward the angular position of the tongue portion 15Be (position of 30 deg). Further, although not clearly shown in the figure, in the strut 36c at the angular position of 150 deg, only the side surface of the tongue portion 15 Be on the angular position side tilts or curves the recirculation groove 36 b side toward the angular position of the tongue portion 15 Be. May be formed. Further, although not explicitly shown in the drawing, the strut 36c may be formed by being tilted or curved toward the recirculation groove 36b from the middle of the strut 36c in the axial direction. Further, although not clearly shown in the figure, in the strut 36c at the angular position of −90 deg adjacent to the strut 36c at the angular position of the tongue 15Be in the circumferential direction, the recirculation groove is similar to the strut 36c at the angular position of 150 deg. The 36b side may be arranged or formed so as to face the angular position of the tongue portion 15Be. Further, although not clearly shown in the figure, the recirculation groove 36b side is the tongue portion of each strut 36c at the angular position of 150 deg and the angular position of −90 deg adjacent to the strut 36c at the angular position of the tongue portion 15 Be in the circumferential direction. It may be arranged or formed toward an angular position of 15 Be. Further, the strut 36c does not have to be provided so as to coincide with the angular position of the tongue portion 15Be. In this case, the strut 36c located at the angular position closest to the angular position of the tongue portion 15Be has the tongue on the recirculation groove 36b side. It may be arranged or formed toward the angular position of the portion 15Be.

By the way, in the compressor 13, as described above, the scroll passage 15Bc is formed by gradually expanding the inner diameter in the circumferential direction from the winding start having the smallest inner diameter, and is connected to the winding end having one round in the circumferential direction. , It is configured to be non-axially symmetric with respect to the rotation axis 14. Therefore, at a small flow rate, the flow of air at the outlet of the diffuser 35 is distorted, and a pressure distribution in which the static pressure increases in the vicinity of the tongue portion 15Be is formed. Therefore, the reverse pressure gradient from the outlet of the diffuser 35 to the tongue portion 15Be increases. Therefore, when the outlet pressure of the impeller 31 increases due to the casing treatment, the dynamic pressure at the outlet of the impeller 31 decreases. Local stall or backflow occurs in the vicinity of the tongue portion 15Be where the reverse pressure gradient is steep. When the recirculation passage is axisymmetric with respect to the rotation axis as in the conventional casing treatment, the dynamic pressure at the impeller outlet decreases uniformly in the circumferential direction, so that the dynamic pressure moves in the radial direction near the tongue. It is difficult to locally increase the pressure and suppress backflow.

In this regard, according to the compressor 13 of the present embodiment, the space of the recirculation passage 15Bf partitioned by the struts 36c at an angle position about the rotation axis 14 of the tongue portion 15Be where the exhaust passage 15Bd branches from the scroll passage 15Bc. The cross-sectional area of the above is reduced from the bleeding groove 36a toward the recirculation groove 36b. Therefore, as in the distribution of the recirculation flow rate m shown in FIG. 5A, the air recirculated in the recirculation passage 15Bf is collected at the angular position of the tongue portion 15Be to obtain a large flow rate. Then, as shown in the distribution of the flow rate m at the outlet of the impeller 31 shown in FIG. 5B, the air flow compressed by the impeller 31 and discharged to the scroll passage 15Bc through the diffuser 35 has a flow rate at the position of the tongue portion 15Be. By increasing, the dynamic pressure increases. As a result, local stall and backflow in the vicinity of the tongue portion 15Be of the scroll passage 15Bc can be suppressed. Moreover, according to the compressor 13 of the present embodiment, since the flow rate of the air recirculated and discharged in the recirculation passage 15Bf is changed, the distribution of the flow rate m of the bleed air groove 36a shown in FIG. As described above, the flow rate of bleeding air to the recirculation passage 15Bf on the inlet side of the air supply in the impeller 31 can be made uniform in the circumferential direction, and the increase in the pressure ratio of the impeller 31 due to the bleeding can be made uniform in the circumferential direction. Therefore, it is possible to suppress the occurrence of backflow as a result of an extremely increase in the pressure ratio and a decrease in the radial dynamic pressure at a specific position.

FIG. 6 is an axial sectional view of another example of the centrifugal compressor according to the present embodiment. FIG. 7 is a circumferential cross-sectional development view of another example of the centrifugal compressor according to the present embodiment. FIG. 8 is a circumferential cross-sectional development view of another example of the centrifugal compressor according to the present embodiment. FIG. 9 is an axial sectional view of another example of the centrifugal compressor according to the present embodiment.

As another example of the compressor 13 of the present embodiment, as shown in FIG. 6, the cross-sectional area is regenerated from the bleed groove 36a at the angular position (the position of 30 deg in FIG. 4) about the rotation axis 14 of the tongue portion 15 Be. It is preferable that the radial width is reduced from the bleeding groove 36a toward the recirculation groove 36b in the space formed by decreasing toward the circulation groove 36b.

In the form shown in FIG. 6, an inclined surface 36d is formed at the position of the recirculation groove 36b so that the peripheral wall (the inner wall surface of the compressor housing 15B of the housing 15) on the outer side in the radial direction of the recirculation passage 15Bf is narrowed in the radial direction. There is. Although not explicitly shown in the drawing, the inclined surface 36d may be provided on the passage wall 36 side of the recirculation passage 15Bf. Further, although not explicitly shown in the drawing, the inclined surface 36d may be provided over the entire area from the bleeding groove 36a to the recirculation groove 36b.

According to such a configuration, the radial width of the space partitioned by the struts 36c is reduced from the bleeding groove 36a toward the recirculation groove 36b, so that the scroll passage 15Bc and the exhaust passage 15Bd are formed. The cross-sectional area of the space of the recirculation passage 15Bf partitioned by the struts 36c decreases from the bleeding groove 36a toward the recirculation groove 36b at an angular position centered on the rotation axis 14 of the branched tongue portion 15Be. There is. Therefore, the flow velocity can be increased on the discharge side of the recirculation flow, and the flow rate distribution of the recirculation can be increased at the angular position of the tongue portion 15Be, so that the above-mentioned effect can be remarkably obtained.

Further, as another example of the compressor 13 of the present embodiment, as shown in FIG. 7, the cross-sectional area is the bleeding groove 36a at the angular position (the position of 30 deg in FIG. 6) about the rotation axis 14 of the tongue portion 15 Be. It is preferable that a part of the groove width of the bleeding groove 36a is narrowly formed in the space formed by decreasing from the to the recirculation groove 36b.

In the form shown in FIG. 7, a protrusion 36e is formed on the groove edge of the bleeding groove 36a on the impeller 31 side so that a part of the groove width of the bleeding groove 36a is narrowed. Although not explicitly shown in the drawing, the protrusion 36e may be formed on the groove edge of the bleed air groove 36a on the air intake port 33 side. Further, although not explicitly shown in the drawing, a plurality of protrusions 36e may be provided.

In a situation where the pressure in the exhaust passage 15Bd rises to become a surge region, the bleeding flow rate of the recirculation flow increases and the work load of the impeller 31 increases, so that the deceleration tends to be strong. In this regard, if a part of the groove width of the bleeding groove 36a in the space partitioned by the strut 36c is formed narrow as in the present embodiment, the pressure of the exhaust passage 15Bd rises and becomes a surge region. In the situation, since the bleed flow rate of the recirculation flow can be suppressed, the increase in the workload of the impeller 31 can be suppressed and the deceleration can be weakened. Therefore, the bleed flow rate of the recirculation flow and the circumferential distribution of the recirculation flow rate to the impeller 31 can be controlled individually.

Further, as another example of the compressor 13 of the present embodiment, as shown in FIGS. 8 and 9, the cross-sectional area is at an angular position (the position of 30 deg in FIG. 8) about the rotation axis 14 of the tongue portion 15 Be. A shutter 36f that opens and closes a part of the groove width of the bleeding groove 36a in a space formed by decreasing from the bleeding groove 36a toward the recirculation groove 36b, and the shutter 36f is closed when the pressure rises based on the pressure of the exhaust passage 15Bd. It is preferable to include an operating mechanism 37 that opens and operates the shutter 36f when the pressure drops while operating.

An empty actuator that operates under the pressure of the diffuser 35 is applied to the operating mechanism 37. Specifically, the operating mechanism 37 includes an operating member 37a that opens and closes the shutter 36f, a pneumatic cylinder 37b that drives the operating member 37a, and a communication pipe 37c that communicates the compression passage 15Bb and the pneumatic cylinder 37b. doing. When the pressure in the exhaust passage 15Bd rises, the pneumatic cylinder 37b drives the operating member 37a to close the shutter 36f. On the other hand, the operating mechanism 37 opens and operates the shutter 36f without driving the operating member 37a of the pneumatic cylinder 37b when the pressure in the exhaust passage 15Bd drops.

As described above, in a situation where the pressure in the exhaust passage 15Bd rises to become a surge region, the bleed flow rate of the recirculation flow increases and the work load of the impeller 31 increases, so that the deceleration tends to be strong. In this regard, in the present embodiment, by closing the shutter 36f when the pressure of the exhaust passage 15Bd rises, the bleed air flow rate of the recirculation flow can be suppressed, so that the increase in the workload of the impeller 31 is suppressed and deceleration is performed. Can be weakened. On the other hand, by opening the shutter 36f when the pressure of the exhaust passage 15Bd drops at the time of a small flow rate, the flow rate of bleeding into the recirculation passage 15Bf becomes peripheral as shown in the flow rate distribution of the bleeding groove 36a shown in FIG. It can be made uniform in the direction, and the amount of work of the impeller 31 due to bleeding can be made uniform in the circumferential direction. Therefore, the bleed flow rate of the recirculation flow and the circumferential distribution of the recirculation flow rate to the impeller 31 can be individually controlled, and the bleed flow rate of the recirculation flow can be controlled according to the pressure of the exhaust passage 15Bd.

Further, according to the exhaust turbine supercharger 11 having the compressor 13 described above, in the compressor 13, local stall and backflow in the vicinity of the tongue portion 15Be of the scroll passage 15Bc can be suppressed while expanding the operating range. Since the efficiency of air supply to the engine is improved, the efficiency of the supercharger can be improved.

Although the present embodiment has described the configuration applied to the compressor 13 of the exhaust turbine supercharger 11 as a centrifugal compressor, the present invention is not limited to this. It can be suitably used for a centrifugal compressor in which an impeller is attached to a rotating shaft and compressed in a housing.

11 Exhaust turbine supercharger 13 Compressor (centrifugal compressor)
14 Rotating shaft 15 Housing 15B Compressor housing 15Ba Air supply passage 15Bb Compression passage 15Bc Scroll passage 15Bd Exhaust passage 15Bf Recirculation passage 15Be Tongue 31 Impeller 32 Blade 33 Air intake 34 Compressed air outlet 35 Diffuser 36 Pass 36b Recirculation groove 36c Strut 36d Inclined surface 36e Protrusion 36f Shutter 37 Acting mechanism 37a Acting member 37b Pneumatic cylinder 37c Communication pipe

Claims (4)

Rotation axis and
An impeller attached to the rotating shaft and having a plurality of blades radially
An air supply passage provided along the extending axial direction of the rotating shaft from the air intake port to the impeller, a compression passage formed in a ring shape along the outer peripheral portion of the impeller, and the compression passage of the compression passage. A spiral-shaped scroll passage communicating with the outer periphery, and a housing having an exhaust passage tangentially branching from a part of the scroll passage and accommodating the rotating shaft and the impeller.
In the housing, an air extraction groove formed in a ring shape along the inner wall surface of the air supply passage and opening to the air supply passage on the impeller side and a recirculation groove opening to the air supply passage on the air intake side. A passage wall that has and forms a recirculation passage,
A plurality of struts provided so as to extend in the axial direction between the inner wall surface of the air supply passage and the passage wall so as to partition the space inside the recirculation passage in the annular direction.
With
At an angle position about the rotation axis of the tongue portion where the exhaust passage branches from the scroll passage, the cross-sectional area of the space partitioned by the struts decreases from the bleeding groove toward the recirculation groove. It is,
The air supply passage facing the passage wall or the passage wall so that the radial width between the inner wall surface of the air supply passage and the passage wall narrows from the bleed groove to the recirculation groove. A centrifugal compressor formed by reducing the cross-sectional area from the bleeding groove toward the recirculation groove due to an inclined surface formed on the inner wall surface of the compressor. Rotation axis and
An impeller attached to the rotating shaft and having a plurality of blades radially
An air supply passage provided along the extending axial direction of the rotating shaft from the air intake port to the impeller, a compression passage formed in a ring shape along the outer peripheral portion of the impeller, and the compression passage of the compression passage. A spiral-shaped scroll passage communicating with the outer periphery, and a housing having an exhaust passage tangentially branching from a part of the scroll passage and accommodating the rotating shaft and the impeller.
In the housing, an air extraction groove formed in a ring shape along the inner wall surface of the air supply passage and opening to the air supply passage on the impeller side and a recirculation groove opening to the air supply passage on the air intake side. A passage wall that has and forms a recirculation passage,
A plurality of struts provided so as to extend in the axial direction between the inner wall surface of the air supply passage and the passage wall so as to partition the space inside the recirculation passage in the annular direction.
With
At an angle position about the rotation axis of the tongue portion where the exhaust passage branches from the scroll passage, the cross-sectional area of the space partitioned by the struts decreases from the bleeding groove toward the recirculation groove. It is,
In the portion formed by reducing the cross-sectional area from the bleeding groove toward the recirculation groove, a part of the groove width of the bleeding groove is formed narrow by the protrusion formed on the groove edge of the bleeding groove. Centrifugal compressor. A shutter that opens and closes a part of the groove width of the bleeding groove in a portion formed by reducing the cross-sectional area from the bleeding groove toward the recirculation groove.
An operating mechanism that closes the shutter when the pressure rises and opens the shutter when the pressure drops based on the pressure in the exhaust passage.
The centrifugal compressor according to claim 1. An exhaust turbine supercharger having a centrifugal compressor according to any one of claims 1 to 3.

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