JP7608751B2 - Centrifugal Compressor - Google Patents

Description

This disclosure relates to a centrifugal compressor.

Conventionally, a centrifugal compressor includes a compressor housing. Patent Document 1 discloses a compressor housing in which a main flow path and a sub-flow path are formed. A compressor impeller is disposed in the main flow path. The sub-flow path is disposed radially outward from the main flow path. The main flow path and the sub-flow path communicate with each other via an upstream slit and a downstream slit. The sub-flow path is provided with ribs for holding a partition wall that separates the main flow path from the sub-flow path.

Japanese Patent Application Publication No. 5-180198

Depending on the flow rate of the fluid (e.g., air) flowing into the compressor impeller, the compressed fluid compressed by the compressor impeller flows in and out of the main flow passage and the secondary flow passage via the downstream slit. If ribs are provided in the secondary flow passage, the compressed fluid and the ribs will interfere with each other, and areas of high and low pressure will be formed in the circumferential direction at the connection between the downstream slit and the main flow passage. Such a flow field with a difference in pressure in the circumferential direction will generate an exciting force that excites the compressor impeller. The compressor impeller will resonate, and vibration stress that may lead to damage may be generated.

The objective of this disclosure is to provide a centrifugal compressor that can reduce the vibration stress generated in the compressor impeller.

In order to solve the above problems, a centrifugal compressor according to one embodiment of the present disclosure includes a main flow path in which an impeller is disposed, a secondary flow path formed radially outward of the impeller than the main flow path, an upstream communication passage connecting the main flow path and the secondary flow path, a downstream communication passage that is closer to the impeller than the upstream communication passage and disposed radially opposite the impeller, connecting the main flow path and the secondary flow path, a partition wall located between the main flow path and the secondary flow path in the radial direction of the impeller and located between the upstream communication passage and the downstream communication passage in the direction of the rotation axis of the impeller, a first support part that is disposed in the secondary flow path and connects an outer circumferential surface of the secondary flow path and the partition wall, and a second support part that is disposed in the secondary flow path at the same position as the first support part in the direction of the rotation axis but at a different position in the direction of the rotation of the impeller with respect to the first support part, connects the outer circumferential surface of the secondary flow path and the partition wall , and has at least one of a shape and a size different from that of the first support part.

Either or both of the first support portion and the second support portion may have an inclined portion that is spaced further away from the downstream communication passage as it moves radially inward.

Either or both of the first support portion and the second support portion may be disposed closer to the upstream communication passage than to the downstream communication passage in the direction of the rotation axis.

This disclosure makes it possible to reduce the vibration stresses that occur in the compressor impeller.

FIG. 1 is a schematic cross-sectional view of a turbocharger. FIG. 2 is an extract of the portion enclosed by the dashed line in FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view of the first support portion shown in FIG. 2 taken along the line IV-IV. 5 is a cross-sectional view of the second support portion shown in FIG. 3 taken along the line VV. 6 is a cross-sectional view of the third support portion shown in FIG. 3 taken along the line VI-VI.

The embodiments of the present disclosure will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not illustrated.

Figure 1 is a schematic cross-sectional view of the turbocharger TC. The direction of the arrow L shown in Figure 1 will be described as the left side of the turbocharger TC. The direction of the arrow R shown in Figure 1 will be described as the right side of the turbocharger TC. As shown in Figure 1, the turbocharger TC includes a turbocharger main body 1.

The turbocharger body 1 comprises a bearing housing 3, a turbine housing 5, and a compressor housing (housing) 7. The turbine housing 5 is connected to the left side of the bearing housing 3 by a fastening bolt 9. The compressor housing 7 is connected to the right side of the bearing housing 3 by a fastening bolt 11.

The turbocharger TC of this embodiment includes a turbine T and a centrifugal compressor C. The turbine T includes a bearing housing 3 and a turbine housing 5. The centrifugal compressor C includes a bearing housing 3 and a compressor housing 7. Below, the turbocharger TC will be described as an example of the centrifugal compressor C. However, the centrifugal compressor C is not limited to the turbocharger TC. The centrifugal compressor C may be incorporated in a device other than the turbocharger TC, or may be a standalone device.

A bearing hole 3a is formed in the bearing housing 3. The bearing hole 3a penetrates the turbocharger TC in the left-right direction. A bearing 13 is provided in the bearing hole 3a. In FIG. 1, a full-floating bearing is shown as an example of the bearing 13. However, the bearing 13 may be another radial bearing such as a semi-floating bearing or a rolling bearing. A shaft 15 is rotatably supported by the bearing 13. A turbine impeller 17 is provided at the left end of the shaft 15. The turbine impeller 17 is rotatably housed in the turbine housing 5. A compressor impeller (impeller) 19 is provided at the right end of the shaft 15. The compressor impeller 19 is rotatably housed in the compressor housing 7.

A housing hole 7a is formed in the compressor housing 7. The housing hole 7a opens to the right side of the turbocharger TC. An attachment member 21 is connected to the housing hole 7a. A main flow path 23 is formed inside the compressor housing 7 and the attachment member 21. The main flow path 23 opens to the right side of the turbocharger TC. The main flow path 23 extends in the direction of the rotation axis of the compressor impeller 19 (hereinafter simply referred to as the rotation axis direction). The main flow path 23 is connected to an air cleaner (not shown). The compressor impeller 19 is disposed in the main flow path 23.

A diffuser passage 25 is formed between the bearing housing 3 and the compressor housing 7. The diffuser passage 25 is formed by the opposing surfaces of the bearing housing 3 and the compressor housing 7 in the direction of the rotation axis. The diffuser passage 25 is formed in an annular shape from the radial inside to the outside of the shaft 15. The diffuser passage 25 is connected to the main passage 23 on the radial inside of the shaft 15. The diffuser passage 25 pressurizes the air that has flowed through the compressor impeller 19.

The compressor housing 7 is formed with a compressor scroll passage 27. The compressor scroll passage 27 is formed in an annular shape. The compressor scroll passage 27 is located, for example, radially outward of the shaft 15 than the diffuser passage 25. The compressor scroll passage 27 is connected to the intake port and the diffuser passage 25 of the engine (not shown). When the compressor impeller 19 rotates, a fluid (e.g., air) is sucked into the compressor housing 7 from the main passage 23. The sucked fluid is pressurized and accelerated in the process of flowing between the blades of the compressor impeller 19. The pressurized and accelerated fluid is pressurized in the diffuser passage 25 and the compressor scroll passage 27. The pressurized fluid (compressed fluid) is led to the intake port of the engine.

The turbine housing 5 is formed with a discharge port 29. The discharge port 29 opens to the left side of the turbocharger TC. The discharge port 29 is connected to an exhaust gas purification device (not shown). The turbine housing 5 is also formed with a communication passage 31 and a turbine scroll passage 33. The communication passage 31 is located radially outward of the turbine impeller 17. The communication passage 31 connects the turbine scroll passage 33 to the discharge port 29 via the turbine impeller 17.

The turbine scroll passage 33 is formed in an annular shape. The turbine scroll passage 33 is located, for example, radially outward of the turbine impeller 17 relative to the communication passage 31. The turbine scroll passage 33 communicates with a gas inlet (not shown). Exhaust gas discharged from an exhaust manifold of an engine (not shown) is introduced to the gas inlet. The exhaust gas introduced from the gas inlet to the turbine scroll passage 33 is introduced to the discharge port 29 via the communication passage 31 and between the blades of the turbine impeller 17. The exhaust gas introduced to the discharge port 29 rotates the turbine impeller 17 during its flow process.

The rotational force of the turbine impeller 17 is transmitted to the compressor impeller 19 via the shaft 15. As described above, the air is pressurized by the rotational force of the compressor impeller 19 and is guided to the intake port of the engine.

Figure 2 is an extracted view of the dashed line portion of Figure 1. As shown in Figure 2, a circulation flow path 100 is formed in the compressor housing 7. The circulation flow path 100 includes a sub-flow path 110, an upstream connecting path 120, and a downstream connecting path 130. In the following, the direction of arrow R shown in Figure 2 will be described as the upstream side of the intake air of the main flow path 23. The direction of arrow L shown in Figure 2 will be described as the downstream side of the intake air of the main flow path 23.

The sub-flow passage 110 is formed radially outward of the compressor impeller 19 than the main flow passage 23. The sub-flow passage 110 is formed away from the main flow passage 23 in the radial direction of the compressor impeller 19 (hereinafter also simply referred to as the radial direction). The sub-flow passage 110 extends in the circumferential direction of the compressor impeller 19 (hereinafter also simply referred to as the circumferential direction or rotational direction) and is formed in a roughly cylindrical shape.

The upstream communication passage 120 and the downstream communication passage 130 are formed between the secondary passage 110 and the main passage 23. The upstream communication passage 120 and the downstream communication passage 130 connect the main passage 23 and the secondary passage 110. The upstream communication passage 120 is located upstream of the intake air of the main passage 23 (on the right side in FIG. 2 ) from the leading edge LE, which is the front edge of the compressor impeller 19. The upstream communication passage 120 is formed in an approximately circular ring shape.

The downstream communication passage 130 is located closer to the compressor impeller 19 than the upstream communication passage 120. The downstream communication passage 130 is located downstream of the intake air (left side in FIG. 2) from the leading edge LE of the compressor impeller 19. The downstream communication passage 130 is arranged radially opposite the compressor impeller 19.

A partition wall 140 is formed between the main flow path 23, the sub-flow path 110, the upstream communication path 120, and the downstream communication path 130. The partition wall 140 is provided between the main flow path 23 and the sub-flow path 110 in the radial direction. The partition wall 140 separates the main flow path 23 and the sub-flow path 110. The partition wall 140 is provided between the upstream communication path 120 and the downstream communication path 130 in the rotation axis direction. The partition wall 140 separates the upstream communication path 120 and the downstream communication path 130.

A plurality of support parts 150 are provided in the secondary flow passage 110. One end of the support part 150 is connected to the outer peripheral surface of the secondary flow passage 110 (the wall part on the outer peripheral side of the secondary flow passage 110), and the other end is connected to the inner peripheral surface of the secondary flow passage 110 (the partition wall 140 on the inner peripheral side of the secondary flow passage 110). The support part 150 supports the partition wall 140. The support part 150 is located at least upstream of the downstream communication passage 130 in the intake air. The support part 150 is located upstream of the leading edge LE of the compressor impeller 19 in the intake air. The support part 150 is arranged closer to the upstream communication passage 120 than the downstream communication passage 130 in the rotation axis direction. In other words, the support part 150 is arranged on the upstream communication passage 120 side than the intermediate position between the downstream communication passage 130 and the upstream communication passage 120.

The support portion 150 includes a first support portion 150a, a second support portion 150b, and a third support portion 150c (see FIG. 3). The first support portion 150a, the second support portion 150b, and the third support portion 150c are arranged at the same position in the rotation axis direction. However, this is not limited thereto, and the first support portion 150a, the second support portion 150b, and the third support portion 150c may be arranged at different positions in the rotation axis direction.

Figure 3 is a cross-sectional view taken along the line III-III in Figure 1. In Figure 3, the cross-sectional view taken along the line II-II corresponds to the cross-sectional view shown in Figure 2. As shown in Figure 3, the first support portion 150a, the second support portion 150b, and the third support portion 150c are arranged at different positions spaced apart from one another in the circumferential direction. In this embodiment, the first support portion 150a, the second support portion 150b, and the third support portion 150c are arranged at equal intervals in the circumferential direction. However, this is not limited thereto, and the first support portion 150a, the second support portion 150b, and the third support portion 150c may be arranged at unequal intervals in the circumferential direction.

Figure 4 is a cross-sectional view of the first support portion 150a shown in Figure 2 taken along the line IV-IV. As shown in Figures 2 and 4, the first support portion 150a is cylindrical. As shown in Figure 4, the cross section of the first support portion 150a perpendicular to the central axis is circular. However, this is not limited thereto, and the first support portion 150a may be an elliptical cylindrical shape in which the cross section perpendicular to the central axis is elliptical. The surfaces of the first support portion 150a facing in the rotation axis direction and the circumferential direction have curved shapes.

The first support portion 150a has an end portion 150a1 (i.e., downstream of the intake air) close to the downstream communication passage 130 (see FIG. 2). The position P1 of the inner diameter end of the end portion 150a1 is the same position as the position P2 of the outer diameter end of the end portion 150a1 in the rotational axis direction. However, this is not limited to this, and the position P1 of the end portion 150a1 may be a position different from the position P2 in the rotational axis direction. For example, the position P1 of the end portion 150a1 may be located on the side away from the downstream communication passage 130 (upstream of the intake air) with respect to the position P2. The position of the end portion 150a1 in the rotational axis direction may be gradually away from the downstream communication passage 130 from the position P2 toward the position P1. In this case, the first support portion 150a has a truncated cone shape.

Figure 5 is a cross-sectional view of the second support portion 150b shown in Figure 3 taken along the line V-V. As shown in Figures 3 and 5, the second support portion 150b is spherical. The surfaces of the second support portion 150b that face each other in the rotation axis direction and the circumferential direction have spherical shapes.

The second support portion 150b has an end portion 150b1 that is close to the downstream communication passage 130 (i.e., downstream of the intake air). The end portion 150b1 includes an inner diameter end position P1, an outer diameter end position P2, and an intermediate position P3 between positions P1 and P2. The inner diameter end position P1 of the end portion 150b1 is located on the side away from the downstream communication passage 130 (upstream of the intake air) with respect to the intermediate position P3 of the end portion 150b1. The position of the end portion 150b1 in the rotation axis direction gradually moves away from the downstream communication passage 130 from the intermediate position P3 toward position P1. In other words, the end portion 150b1 has an inclined portion 150b2 that moves away from the downstream communication passage 130 as it moves radially inward with respect to the intermediate position P3.

Figure 6 is a cross-sectional view of the third support part 150c shown in Figure 3 taken along the line VI-VI. As shown in Figures 3 and 6, the third support part 150c has a quadrangular prism shape with a trapezoidal cross section including the central axis of rotation of the compressor impeller 19. In Figure 3, the cross section of the third support part 150c perpendicular to the central axis of rotation of the compressor impeller 19 is also trapezoidal. However, this is not limited thereto, and the cross section of the third support part 150c perpendicular to the central axis of rotation of the compressor impeller 19 may also be rectangular.

The third support portion 150c has an end portion 150c1 close to the downstream communication passage 130 (i.e., downstream of the intake air). The position P1 of the inner diameter end of the end portion 150c1 is located on the side away from the downstream communication passage 130 (upstream of the intake air) with respect to the position P2 of the outer diameter end of the end portion 150c1. The position of the end portion 150c1 in the rotation axis direction gradually moves away from the downstream communication passage 130 from position P2 toward position P1. In other words, the end portion 150c1 has an inclined portion 150c2 that moves away from the downstream communication passage 130 as it moves radially inward. Note that when the first support portion 150a has a truncated cone shape, it may have an inclined portion 150c2 that moves away from the downstream communication passage 130 as it moves radially inward, as shown in FIG. 6.

In this embodiment, six support parts 150 are provided in the circumferential direction in the sub-channel 110. However, the number of support parts 150 is not limited to this, and may be five or less, or seven or more. In this embodiment, the first support part 150a is arranged at the vertically uppermost position of the sub-channel 110. The multiple support parts 150 are arranged in the following order, clockwise from the first support part 150a on the vertical upper side: second support part 150b, third support part 150c, first support part 150a, third support part 150c, second support part 150b. However, the arrangement order of the multiple support parts 150 is not limited to this. For example, the second support part 150b, third support part 150c, first support part 150a, second support part 150b, third support part 150c, may be arranged in the following order, clockwise from the first support part 150a on the vertical upper side. Additionally, two circumferentially adjacent support portions 150 may have the same shape.

Next, the operation of the circulation flow path 100 of this embodiment will be described with reference to Figures 2 and 3. When the flow rate of the fluid (air) flowing into the compressor impeller 19 decreases, the compressed fluid compressed by the compressor impeller 19 flows into the secondary flow path 110 via the downstream communication path 130 and returns to the main flow path 23 from the upstream communication path 120. In this way, the apparent flow rate flowing into the compressor impeller 19 increases, and the operating range of the centrifugal compressor C on the small flow rate side is expanded.

If ribs for supporting the partition wall 140 are provided in the secondary flow passage 110, the compressed fluid will interfere with the ribs, and high and low pressure areas will be formed in the circumferential direction at the connection between the downstream communication passage 130 and the primary flow passage 23. Such a flow field with a circumferential pressure difference will generate an excitation force that excites the compressor impeller 19. The compressor impeller 19 will resonate, and vibration stress that may lead to damage may be generated.

Therefore, in this embodiment, multiple types of support parts 150 (first support part 150a, second support part 150b, third support part 150c) are provided in the sub-flow passage 110. As shown in FIG. 3, two support parts 150 adjacent to each other in the circumferential direction have different shapes.

For example, the second support portion 150b is adjacent to the first support portion 150a in the circumferential direction. Here, the second support portion 150b is spherical, and the first support portion 150a is cylindrical. In this way, the second support portion 150b and the first support portion 150a, which are adjacent to each other in the circumferential direction, have different shapes.

The second support portion 150b is adjacent to the third support portion 150c in the circumferential direction. Here, the second support portion 150b is spherical, and the third support portion 150c is rectangular prism-shaped. In this way, the second support portion 150b and the third support portion 150c, which are adjacent to each other in the circumferential direction, have different shapes.

However, this is not limited thereto, and two support parts 150 adjacent in the circumferential direction may have the same shape. In this case, at least one support part 150 among the multiple support parts 150 arranged in the circumferential direction has a shape different from the other support parts 150.

In this manner, in this embodiment, at least one of the multiple support parts 150 has a different shape. As described above, when the compressed fluid compressed by the compressor impeller 19 flows into the sub-flow passage 110 through the downstream communication passage 130, it interferes with the multiple support parts 150 (first support part 150a, second support part 150b, third support part 150c). At this time, a high pressure region and a low pressure region are formed in the circumferential direction in the communication part between the downstream communication passage 130 and the main flow passage 23. Here, for example, the first support part 150a and the second support part 150b have different shapes. Therefore, the pressure difference caused by the first support part 150a and the pressure difference caused by the second support part 150b can be made different from each other. By breaking the periodic symmetry of the pressure difference caused by each support part in the circumferential direction, the excitation force exciting the compressor impeller 19 can be reduced. As a result, the vibration stress generated in the compressor impeller 19 can be reduced.

In addition, when the shapes of two circumferentially adjacent support parts 150 are different from each other, the vibration stress generated in the compressor impeller 19 can be reduced more than when the shapes of two circumferentially adjacent support parts 150 are the same.

In addition, the first support portion 150a and the second support portion 150b have a curved surface (spherical surface) on the outer circumferential surface. This makes it possible to reduce the pressure (excitation force) that occurs when the compressed fluid interferes with the first support portion 150a and the second support portion 150b. As a result, the vibration stress generated in the compressor impeller 19 is reduced.

The second support portion 150b and the third support portion 150c have ends 150b1 and 150c1 on the downstream side of the intake air. The ends 150b1 and 150c1 have inclined portions 150b2 and 150c2 that are farther away from the downstream communication passage 130 as they move radially inward. The energy of the compressed fluid when it collides with the support portion 150 decreases as it moves farther away from the downstream communication passage 130. This makes it possible to reduce the pressure (excitation force) generated when the compressed fluid interferes with the second support portion 150b and the third support portion 150c compared to when the inclined portions 150b2 and 150c2 are not formed. As a result, it is possible to reduce the vibration stress generated in the compressor impeller 19.

The support portion 150 is disposed upstream of the leading edge LE of the compressor impeller 19 in the direction of the rotation axis. The support portion 150 is disposed closer to the upstream communication passage 120 than the downstream communication passage 130 in the direction of the rotation axis. The further the support portion 150 is from the downstream communication passage 130, the more the pressure (excitation force) generated when the compressed fluid interferes with the support portion 150 can be reduced. As a result, the vibration stress generated in the compressor impeller 19 can be reduced.

In this embodiment, an example in which at least one of the multiple support parts 150 has a different shape has been described. However, this is not limited to this, and at least one of the multiple support parts 150 may have a size different from the other support parts 150. For example, the multiple support parts 150 may include a cylindrical first support part 150a having a different size from each other. In other words, at least one of the multiple support parts 150 may have a projected area (size) in the rotation axis direction, circumferential direction, or in the inflow direction of the compressed fluid that has flowed back from the other support parts 150. Even if at least one of the multiple support parts 150 has a different size, the same action and effect as the above embodiment can be obtained. In other words, at least one of the multiple support parts 150 may have a different shape and size (projected area) from the other support parts 150.

Although the embodiments of the present disclosure have been described above with reference to the attached drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can conceive of various modified or revised examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

In the above embodiment, an example was described in which the support portion 150 includes three types of support portions (first support portion 150a, second support portion 150b, and third support portion 150c). However, this is not limited, and the support portion 150 may include at least two types of support portions. For example, the support portion 150 may include the first support portion 150a and the second support portion 150b, but may not include the third support portion 150c.

In the above embodiment, an example has been described in which the third support portion 150c has a trapezoidal rectangular prism shape in cross section including the central axis of rotation of the compressor impeller 19. However, this is not limited thereto, and the third support portion 150c may have, for example, a rectangular parallelepiped shape.

In the above embodiment, an example has been described in which the multiple support parts 150 are arranged closer to the upstream communication passage 120 than the downstream communication passage 130 in the rotational axis direction. However, this is not limited to this, and one of the multiple support parts 150 may be arranged closer to the downstream communication passage 130 than the upstream communication passage 120 in the rotational axis direction. In other words, one or both of the multiple support parts 150 may be arranged closer to the upstream communication passage 120 than the downstream communication passage 130 in the rotational axis direction.

This disclosure can be used in centrifugal compressor C.

C Centrifugal compressor 19 Compressor impeller (impeller)
23 Main flow path 100 Circulation flow path 110 Sub-flow path 120 Upstream communication path 130 Downstream communication path 140 Partition wall 150 Support portion 150a First support portion 150b Second support portion 150b1 End portion 150b2 Inclined portion 150c Third support portion 150c1 End portion 150c2 Inclined portion

Claims (3)

a main flow path in which an impeller is disposed;
A sub-flow passage formed radially outward of the impeller from the main flow passage;
an upstream communication passage that communicates the main flow passage and the sub flow passage;
a downstream communication passage disposed closer to the impeller than the upstream communication passage and facing the impeller in a radial direction, the downstream communication passage communicating the main flow passage with the sub flow passage;
a partition wall located between the main passage and the sub passage in a radial direction of the impeller and between the upstream communication passage and the downstream communication passage in a rotational axis direction of the impeller;
a first support portion disposed in the sub-flow passage and connecting an outer circumferential surface of the sub-flow passage and the partition wall;
a second support portion that is disposed in the sub-flow passage at the same position as the first support portion in the rotation axis direction and at a different position in the rotation direction of the impeller with respect to the first support portion, connects an outer circumferential surface of the sub-flow passage and the partition wall , and has at least one of a shape and a size different from that of the first support portion;
A centrifugal compressor comprising: The centrifugal compressor according to claim 1, wherein either or both of the first support portion and the second support portion have an inclined portion that is spaced farther from the downstream communication passage in the radially inner direction. The centrifugal compressor according to claim 1 or 2, wherein either or both of the first support portion and the second support portion are disposed closer to the upstream communication passage than the downstream communication passage in the direction of the rotation axis.

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