JP5533412B2 - Compressor - Google Patents

Description

  The present invention relates to a compressor provided with a casing treatment.

  As means for expanding the operating range on the small flow rate side of the compressor, a circulation type casing treatment has been proposed and already used (for example, Patent Documents 1 to 4).

Patent Documents 5 and 6 are disclosed as means for controlling the circulation amount in the bypass recirculation path.
Furthermore, Patent Document 7 is disclosed as a turbocharger flow rate control means.

Patent Documents 1 and 2 relate to a centrifugal compressor, and extract gas from a slit installed in a casing where the impeller is located, and circulate the gas upstream of the impeller.
Patent Document 3 relates to an axial compressor, and is provided with a slit extending in a circumferential direction in a casing where an impeller is positioned, and gas is circulated in the slit.
Patent Document 4 relates to an axial compressor, which extracts gas from a slit installed in a casing where the impeller is located and circulates the gas upstream of the impeller.

In Patent Document 5, a bypass control valve is provided in a bypass recirculation path of a centrifugal compressor to control a circulation amount.
In Patent Document 6, a circulation member is controlled by providing a guide member for controlling a circumferential speed component in a bypass reflux path of a centrifugal compressor.
Patent Document 7 includes a variable nozzle that controls the amount of gas flowing into the turbocharger.

JP 2009-209858 A, “Centrifuge compressor” US Pat. No. 4,743,161, “COMPRESSORS” US Pat. No. 5,707,206, “TURBOMACHINE” US Pat. No. 5,607,284, “BAFFLED PASSAGE CASING TREATMENT FOR COMPRESOR BLADES” Japanese Patent Application Laid-Open No. 2006-2650, “Centrifuge Compressor by Linking Inlet Vane and Bypass Control Valve” Japanese Patent Application Laid-Open No. 2006-342682, “Method and apparatus for expanding the operating range of a centrifugal compressor” Japanese Unexamined Patent Publication No. 2000-120442, “Variable Capacity Turbocharger”

  In the compressor, when the above-described conventional casing treatment is applied, there are the following problems.

In the conventional casing treatment, the bleed flow rate may be small, and as a result, it is difficult to expand to the small flow rate side operation region, and the efficiency at the small flow rate deteriorates.
Moreover, in the conventional casing treatment described above, since bleed is always performed, the efficiency may be deteriorated on the maximum flow rate side.

  In addition, when the flow rate control means of Patent Documents 5 and 6 are applied, the conventional casing treatment (or bypass reflux path) has a problem that the efficiency is greatly reduced because the flow path area is small and the pressure loss is large. .

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a compressor capable of expanding the operating range to a small flow rate side without deteriorating the efficiency while maintaining the maximum flow rate that can be compressed, and thereby operating in a wide flow range. .

According to the present invention, an impeller that rotates about an axis and compresses gas;
A casing that surrounds the impeller and forms a gas main flow path on the inside thereof;
Circulation channels that open to the inner surface of the casing on the upstream side and the downstream side of the main channel,
A circulation amount control device capable of continuously controlling the flow rate of the gas flowing through the circulation channel,
The circulation channel has an upstream end and a downstream end that respectively open on the casing inner surface on the upstream side and the downstream side of the main channel, and an intermediate portion that connects the upstream end and the downstream end, and the upstream side of the circulation channel The end is located downstream of the upstream end of the impeller in the main flow path,
At least a part of the intermediate portion has a spherical shape whose outer surface and inner surface are centered on a point on the axis,
The circulation amount control device includes a plurality of vanes extending in an arc shape along the spherical outer surface and the inner surface, and an actuator for swinging the plurality of vanes around a swing shaft passing through a point on the axis. A compressor characterized by comprising: is provided.

According to the first embodiment of the present invention, a moving blade row and a stationary blade row for pressurizing the gas in the direction of the axial center are arranged in the main flow path, and the impeller is the moving blade row. ,
A centrifugal impeller is disposed in the main flow path and located on the downstream side of the moving blade row and the stationary blade row.

  According to a second embodiment of the present invention, the impeller is a centrifugal impeller that pressurizes the gas by sending the gas radially outward with respect to the shaft center.

According to the configuration of the present invention, at least a part of the intermediate portion of the circulation flow path has a spherical shape whose outer surface and inner surface are centered on a point on the axis. It can be taken greatly.
Further, the circulation amount control device includes a plurality of vanes extending in an arc shape along the spherical outer surface and the inner surface, so that the adjustment range of the opening degree of the circulation flow path is increased by the swinging of the plurality of vanes. be able to.
As a result, if the flow rate of the circulation channel is increased, the operating range can be expanded to the small flow rate side as described above, and if the flow rate of the circulation channel is decreased to zero, there is no bleed. The maximum flow rate that can be compressed can be maintained. Therefore, by controlling the flow rate of the circulation flow path with the circulation amount control device, the operating range can be expanded to the small flow rate side without deteriorating the efficiency while maintaining the maximum flow rate that can be compressed.

1 is an overall configuration diagram of a compressor (composite turbo compressor) according to a first embodiment of the present invention. It is AA sectional drawing of FIG. It is a static pressure distribution map of the compressor by a 1st embodiment of the present invention. It is a related figure of the flow volume, pressure ratio, and efficiency in the conventional composite turbo compressor. It is a related figure of the flow, pressure ratio, and efficiency in the compressor by a 1st embodiment of the present invention. It is a whole block diagram of the compressor (centrifugal compressor) by 2nd Embodiment of this invention. It is a whole block diagram of the compressor (axial flow compressor) by 3rd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is an overall configuration diagram of a compressor according to a first embodiment of the present invention.
In this figure, the compressor 10 according to the first embodiment of the present invention is a composite turbo compressor including an axial flow compression unit 12, a centrifugal compression unit 14, a casing 16, a circulation flow path 18, and a circulation amount control device 20. .
Although the compressor 10 by 1st Embodiment of this invention is a compressor for superchargers which compresses air, for example, this invention is not limited to this, Other compressors may be sufficient.

  The axial flow compression unit 12 includes a moving blade row 12a that rotates about the axis ZZ, and a stationary blade row 12b that does not rotate on the downstream side (right side in the drawing) of the moving blade row 12a. In this example, the axial flow compression unit 12 is a single-stage axial flow compression unit including one row of moving blade rows 12a and one row of stationary blade rows 12b, but the present invention is not limited to this, and a plurality of It may be a multi-stage axial flow compression section comprising a moving blade row 12a and a stationary blade row 12b. The moving blade row 12a and the stationary blade row 12b pressurize the gas in the direction of the axis ZZ.

The centrifugal compression unit 14 is disposed coaxially with the axial flow compression unit 12 on the downstream side (right side in the drawing) of the axial flow compression unit 12, and has a centrifugal impeller 14a that rotates about the same axis ZZ. . The centrifugal impeller 14 pressurizes the gas by sending the gas radially outward with respect to the axis ZZ.
The axis of rotation (not shown) of the axial flow compression unit 12 and the centrifugal compression unit 14 may be the same or different. In the case of different shafts, the respective rotation speeds may be the same or different.

The casing 16 surrounds the moving blade row 12a and the stationary blade row 12b of the axial flow compression unit 12 and the centrifugal impeller 14a of the centrifugal compression unit 14, and constitutes the main flow path 15 for gas 1 inside thereof.
The gas 1 is, for example, air, but may be other gases (exhaust gas, nitrogen gas, etc.).
The main flow path 15 is a space between the inner surface 16a of the casing 16 and the rotor 13 to which the rotor blade row 12a is attached, and between the inner surface 16a of the casing 16 and the cone portion 17 to which the wing portion of the centrifugal impeller 14a is attached. It is. The cross-sectional shape of the main channel 15 is a donut shape (hollow circle).

  With the configuration described above, the compressor 10 according to the first embodiment of the present invention compresses the low-pressure gas 1 sucked from the front into the medium-pressure gas 2 by the axial flow compression unit 12, and again converts this to the centrifugal compression unit 14. The gas 3 is compressed and then sent to the outside as a high-pressure gas 3 having a higher pressure. Therefore, a high compression ratio can be achieved by the axial flow compression unit 12 and the centrifugal compression unit 14.

In FIG. 1, a circulation flow path 18 is a flow path that directly communicates the casing inner surface 16a on the upstream side (left side in the figure) and the downstream side (right side in the figure) of the rotor blade row 12a.
The upstream end 18a of the circulation flow path 18 is open to the casing inner surface 16a located on the downstream side of the moving blade row 12a, and the downstream end 18b of the circulation flow path 18 is the casing located on the upstream side of the moving blade row 12a. Open on the inner surface. An intermediate portion 18 c of the circulation flow path 18 connecting the upstream end 18 a and the downstream end 18 b is provided outside the inner surface 16 a of the casing 16.

  The opening shape of the upstream end 18a and the downstream end 18b of the circulation flow path 18 to the inner surface 16a of the casing 16 is preferably one or a plurality of slit shapes extending continuously or intermittently in the circumferential direction.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.
As shown in FIGS. 1 and 2, at least a part of the intermediate portion 18 c of the circulation channel 18 has a spherical shape whose outer surface 19 a and inner surface 19 b are centered on a point O on the axis ZZ. . In this example, the outer surface 19a is a part of a spherical surface with a radius R1 centered on the point O, and the inner surface 19b is a part of a spherical surface with a radius R2 centered on the point O.

  Therefore, in this portion, the cross-sectional shape in a plane passing through the point O of the circulation flow path 18 is a hollow circle centered on the point O. However, the present invention is not limited to the hollow circular cross-sectional shape, and may be an arc shape in which a part thereof is divided.

The circulation amount control device 20 is configured to continuously control the flow rate of the gas flowing through the circulation flow path 18.
In this example, the circulation amount control device 20 includes a plurality of vanes 20a extending in an arc shape along the spherical outer surface 19a and inner surface 19b, and a plurality of swinging shafts 21 passing through a point O on ZZ. Actuator 20b for swinging the vane 20a.
The swinging of the plurality of vanes 20a is preferably synchronized. In order to achieve this synchronization, it is preferable to use a synchronization mechanism that synchronizes the plurality of swing shafts 21. Further, the respective swing shafts 21 may be synchronized by separate actuators 20b.

  The cross-sectional shape along the gas flow of the vane 20a is a flat plate in this example, but is preferably an airfoil, and may have other shapes.

In FIG. 2, twelve vanes 20 a are provided at a pitch of 30 degrees in the circumferential direction, and each of the vanes 20 a swings around the swing shaft 21 to fully close the hollow circular flow path of the circulation flow path 18. It is like that. Further, the circulation channel 18 can be fully opened by swinging the swing shaft 21 by 90 degrees from the fully closed position.
Therefore, with this configuration, the flow rate of the circulation channel 18 can be controlled from fully closed to fully open.

Further, the plurality of vanes 20a described above oscillate about the oscillating shaft 21 to continuously control the flow rate, so that the gas passing through the vane 20a is centered on the axis ZZ depending on the direction of the vane. A swirl is added.
The direction of this swirl may be the same forward swirl as the rotation direction of the compressor or a reverse swirl opposite to the rotation direction of the compressor. In addition, the swirl of the entire gas flowing into the rotor blade row 12a may be controlled by this swirl to increase efficiency.

  The flow rate of the gas flowing through the circulation flow path 18 can be continuously controlled by swinging the plurality of vanes 20a synchronously by the circulation amount control device 20 described above.

FIG. 3 is a static pressure distribution diagram of the compressor according to the first embodiment of the present invention.
In this figure, the horizontal axis is the axial position (mm) relative to the downstream end of the centrifugal impeller 14a, and the vertical axis is the radial distance (mm) from the rotation center (ZZ axis) and the inlet side pressure. This is the static pressure ratio.
The compressor 10 in the figure shows the upper half of the rotation center (Z-Z axis).
Moreover, the curve shown in the upper part of the composite turbocompressor 10 is a static pressure ratio corresponding to each part of the compressor 10 when the circulation flow path 18 is not provided.
Further, A1, A2, A3, and A4 in the figure indicate the static pressure on the upstream side of the moving blade row 12a, the position of the moving blade row 12a, the position of the stationary blade row 12b, and the upstream side of the centrifugal impeller 14a, respectively. Yes. This static pressure distribution diagram is a simulation result under a predetermined condition.

According to the first embodiment of the present invention, the upstream end 18a of the circulation flow path 18 is upstream of the centrifugal impeller 14a of the centrifugal compressor 14, and the static pressure is higher than the position of the moving blade row 12a and the centrifugal impeller 14a. It is set to a high position.
That is, in the example of FIG. 3, the upstream end 18a of the circulation flow path 18 is set at the position of the stationary blade row 12b corresponding to A3.

  With this configuration, the gas in the first embodiment of the present invention is compared with the conventional casing treatment in which the gas extraction position is the intermediate position (A4) of the centrifugal impeller 14a or the intermediate position (A2) of the moving blade row 12a. Since the static pressure at the extraction position (A3) is high and the differential pressure with the upstream side (A1) of the moving blade row 12a is large, a large amount of gas can be extracted.

FIG. 4 is a relationship diagram of flow rate, pressure ratio, and efficiency in a conventional composite turbo compressor.
In this figure, the horizontal axis represents the flow rate, and the vertical axis represents the pressure ratio and efficiency. Moreover, the solid line in the figure indicates the case where there is no circulation channel (that is, casing treatment), and the broken line indicates the case where there is a circulation channel.
Further, in the figure, B1 is a characteristic at the maximum rotational speed, B2 is a characteristic at the minimum rotational speed, B3 is a characteristic at the intermediate speed, and B4 is a surge line. That is, when there is no circulation channel, the conventional composite turbo compressor schematically shows that the region surrounded by B1, B2, and B4 is the operation region.

In FIG. 4, when there is a circulation flow path, even if the actual gas flow rate decreases, the apparent flow rate flowing into the compressor impeller is increased or maintained by the amount corresponding to the extraction flow rate. As shown by broken lines in FIG. 5, the lines B1, B2, and B4 move to the small flow rate side.
However, as described above, the conventional extraction position has a low differential pressure with respect to the upstream side of the axial flow compression section, so that the extraction flow rate is small and the movement to the small flow rate side operation region is small.
Moreover, in the conventional casing treatment, since the bleed is always performed, the maximum flow rate that can be compressed may be reduced by an amount corresponding to the bleed flow rate.

FIG. 5 is a relationship diagram of the flow rate, pressure ratio, and efficiency in the compressor according to the first embodiment of the present invention.
In this figure, the thick solid line in the figure is when the circulation channel 18 is fully closed, and the broken line is when the circulation channel 18 is fully open. When fully closed, this corresponds to the case where there is no circulation channel (that is, casing treatment) in the conventional example of FIG. The thin solid line is the intermediate position between fully closed and fully opened, that is, the case where the flow rate flowing through the circulation flow path 18 is the maximum and minimum intermediate flow rate.

  As in FIG. 4, B1 in the figure indicates the characteristic at the maximum rotational speed, B2 indicates the characteristic at the minimum rotational speed, B3 indicates the characteristic at the intermediate speed, and B4 indicates the surge line. That is, when there is no circulation flow path, the compressor 10 according to the first embodiment of the present invention schematically shows that the region surrounded by B1, B2, and B4 is the operation region.

In FIG. 5, when the circulation flow path is fully open, even if the actual gas flow rate decreases, the apparent flow rate flowing into the compressor impeller is increased or maintained by the amount corresponding to the extraction flow rate. As indicated by broken lines inside, the lines B1, B2, and B4 move to the small flow rate side.
In this case, in the first embodiment of the present invention, as shown in FIG. 3, the upstream end 18a (bleeding position) of the circulation flow path 18 is a position where the static pressure is higher than the positions of the moving blade row 12a and the centrifugal impeller 14a. Since it is set to (A3), since a differential pressure with the upstream (A1) of the axial flow compression part 12 is large, a large amount of gas can be extracted.
As a result, in the first embodiment of the present invention, the operating range can be expanded to the small flow rate side.

In the first embodiment of the present invention, since the circulation amount control device 20 capable of continuously controlling the flow rate of the gas flowing through the circulation channel 18 is provided, if the flow rate of the circulation channel 18 is increased, As described above, the operating range can be expanded to the small flow rate side, and if the flow rate of the circulation flow path 18 is reduced to zero, the maximum flow rate that can be compressed without extraction is maintained. Furthermore, as shown by a thin solid line in FIG. 5, the flow rate of the circulation flow path 18 can be operated at an intermediate flow rate.
Therefore, by controlling the flow rate of the circulation flow path 18 with the circulation amount control device 20, the operating range can be expanded to the small flow rate side without deteriorating the efficiency while maintaining the maximum flow rate that can be compressed.

4 and 5, a broken line C (thick solid line) in the figure schematically shows the relationship between the flow rate and the pressure ratio under engine operating conditions.
From the comparison between FIG. 4 and FIG. 5, it can be seen that the efficiency in FIG. 5 is higher at the folding position C1 of the broken line C.

The reason for this is that in conventional casing treatments, the flow rate of gas flowing through the circulation channel is small, and the apparent increase in flow rate flowing into the compressor impeller is limited, so that the efficiency cannot be maintained and the flow rate is reduced to the low flow rate side. It is considered that the operating range has been expanded.
On the other hand, in the present invention, the flow rate of the gas flowing through the circulation channel is large, the apparent flow rate flowing into the compressor impeller can be increased, and it is considered that the efficiency hardly decreases.

As described above, in the first embodiment of the present invention, the axial flow compression unit 12 is combined with the centrifugal compression unit 14 and the air is extracted from the axial flow stage stationary blade unit having a higher static pressure. The circulation flow rate can be increased.
As a result, the apparent flow rate increases and the entire operating range of the compressor shifts to the small flow rate side. Furthermore, by continuously controlling the flow rate of the circulation flow path 18 with the circulation amount control device 20, the compressor 10 operable in a wide range can be realized.

(Second Embodiment)
FIG. 6 is an overall configuration diagram of a compressor according to the second embodiment of the present invention.
The compressor according to the second embodiment is obtained by omitting the axial flow compression unit 12 in the first embodiment. That is, the compressor 10 according to the second embodiment is a centrifugal compressor including the centrifugal compressor 14.
In this case, as shown in FIG. 6, the upstream end 18a of the circulation flow path 18 is located downstream of the upstream end of the centrifugal impeller 14a in the main flow path 15, and the downstream end 18b of the circulation flow path 18 is the main flow path. In FIG. 15, it is located upstream from the upstream end of the centrifugal impeller 14a. Other configurations in the second embodiment may be the same as those in the first embodiment described above, or may be changed as appropriate.

(Third embodiment)
FIG. 7 is an overall configuration diagram of a compressor according to the third embodiment of the present invention.
The compressor according to the third embodiment is obtained by omitting the centrifugal compression unit 14 in the first embodiment. That is, the compressor 10 according to the third embodiment is an axial flow compressor including the axial flow compression unit 12.
In this case, as shown in FIG. 7, the upstream end 18a of the circulation flow path 18 is located downstream of the upstream end of the moving blade row 12a in the main flow path 15, and the downstream end 18b of the circulation flow path 18 is In the path 15, it is located upstream from the upstream end of the moving blade row 12a. Other configurations in the third embodiment may be the same as those in the first embodiment described above, or may be changed as appropriate.

  In addition, this invention is not limited to embodiment mentioned above, is shown by description of a claim, and also includes all the changes within the meaning and range equivalent to description of a claim.

1 low pressure gas, 2 medium pressure gas, 3 high pressure gas,
10 compressor, 12 axial flow compression section,
12a impeller (moving blade row), 12b stationary blade row, 13 rotor,
14 Centrifugal compression part, 14a impeller (centrifugal impeller),
15 main flow path, 16 casing, 16a inner surface,
17 cone part, 18 circulation flow path,
18a upstream end, 18b downstream end, 18c middle part,
19a outer surface, 19b inner surface,
20 Circulation amount control device, 20a Vane,
20b Actuator, 21 Oscillating shaft

Claims (4)

An impeller that rotates about an axis and compresses gas;
A casing that surrounds the impeller and forms a gas main flow path on the inside thereof;
Circulation channels that open to the inner surface of the casing on the upstream side and the downstream side of the main channel,
A circulation amount control device capable of continuously controlling the flow rate of the gas flowing through the circulation channel,
The circulation channel has an upstream end and a downstream end that respectively open on the casing inner surface on the upstream side and the downstream side of the main channel, and an intermediate portion that connects the upstream end and the downstream end, and the upstream side of the circulation channel The end is located downstream of the upstream end of the impeller in the main flow path,
At least a part of the intermediate portion has a spherical shape whose outer surface and inner surface are centered on a point on the axis,
The circulation amount control device includes a plurality of vanes extending in an arc shape along the spherical outer surface and the inner surface, and an actuator for swinging the plurality of vanes around a swing shaft passing through a point on the axis. The compressor characterized by comprising. In the main flow path, a moving blade row and a stationary blade row that pressurize the gas in the direction of the axial center are arranged, and the impeller is the moving blade row,
2. The compressor according to claim 1, further comprising a centrifugal impeller disposed in the main flow path and positioned downstream of the moving blade row and the stationary blade row.   The compressor according to claim 1, wherein the impeller is a centrifugal impeller that pressurizes the gas by sending the gas radially outward with respect to the shaft center. 2. The main flow path includes a moving blade row and a stationary blade row that pressurize the gas in the direction of the axis, and the impeller is the moving blade row. Compressor.