Centrifugal Compressors and Turbochargers

Abstract

This centrifugal compressor is provided with: an impeller including a main body portion, and a plurality of blades provided on an outer circumferential surface of the main body portion; an intake passage (130) facing the impeller in the direction of the axis of rotation thereof; and a throttling mechanism which includes a throttling member (first throttling member (210)) provided in the intake passage (130), and in which a ratio obtained by dividing a distance (LL) between an outer circumferential edge of a leading edge (LE) of the blades and the throttling member by a maximum protrusion height (hmax) of the throttling member protruding from an inner wall surface of the intake passage (130) is at most equal to 4.

Description

[Technical field]

[0001] This disclosure relates to a centrifugal compressor and a turbocharger. This application claims the benefit of priority from Japanese Patent Application No. 2019-086357, filed on April 26, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, a turbocharger is provided with a centrifugal compressor. For example, in the centrifugal compressor provided in the turbocharger described in Patent Document 1, an intake passage is formed upstream of the compressor impeller. A throttling member is provided in the intake passage. A plurality of throttling members are arranged side by side in the circumferential direction of the compressor impeller. The throttling member is driven by an actuator and protrudes radially inward into the intake passage, thereby throttling the intake passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-173051 A Summary of the Invention [Problem to be solved by the invention]

[0004] By narrowing the intake passage with a throttling member, the decrease in adiabatic efficiency at low flow rates can be suppressed. There is a need to develop technology that can further suppress the decrease in adiabatic efficiency when the intake passage is narrowed in this way.

[0005] An object of the present disclosure is to provide a centrifugal compressor and a turbocharger capable of suppressing a decrease in adiabatic efficiency. [Means for solving the problem]

[0006] In order to solve the above problems, a centrifugal compressor according to one embodiment of the present disclosure includes: a main body, an impeller having a plurality of blades provided on an outer circumferential surface of the main body, an intake passage facing the impeller in a rotational axis direction, and a housing accommodating the impeller, the housing including a first housing member including an intake port and a second housing member including a shroud portion facing the impeller from a radially outer side of the impeller, an inner diameter of the shroud portion increasing as it is separated from the first housing member, and a throttling mechanism including a throttling member provided in the intake passage, the throttling member being movable in the radial direction of the impeller and being switched between a throttling position where it protrudes into the intake passage and a retracted position radially outward from the throttling position, and forming a circular annular hole in the intake passage at the throttling position, the throttling mechanism having a throttling member and a throttling member having a ratio of a distance between an outer circumferential end of a leading edge of the blade and the throttling member divided by a maximum protruding height of the throttling member protruding from an inner wall surface of the intake passage being 4 or less. The throttling member includes a first throttling member and a second throttling member, each of which can be moved to a throttling position and a retracted position by rotating around a predetermined rotation shaft portion, and at the throttling position, a circular annular hole is formed in the intake passage by the two members, the first throttling member and the second throttling member. .

[0007] In addition, the throttle member may have an opposing surface that faces the outer peripheral end in the axial direction of the impeller, and the opposing surface may be located between the axial position of the outer peripheral end and the axial position of the inner peripheral end of the leading edge.

[0008] In order to solve the above problem, a turbocharger according to one aspect of the present disclosure is provided with the centrifugal compressor. R . Effect of the Invention

[0009] According to the present disclosure, it is possible to suppress a decrease in insulation efficiency. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a turbocharger. [Diagram 2] FIG. 2 is an extract of the portion enclosed by the dashed line in FIG. [Diagram 3] FIG. 3 is an exploded perspective view of members that constitute the link mechanism. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a first diagram for explaining the operation of the link mechanism (throttle mechanism). [Figure 6] FIG. 6 is a second diagram for explaining the operation of the link mechanism. [Figure 7] FIG. 7 is a third diagram for explaining the operation of the link mechanism. [Figure 8] FIG. 8 is an extracted diagram of the part enclosed by the two-dot chain line in FIG. [Figure 9] FIG. 9 is a graph showing the relationship between the distance and the improvement rate of the adiabatic efficiency. [Figure 10] FIG. 10 is a diagram for explaining the range of arrangement of the protrusions of the first diaphragm member. [Figure 11] FIG. 11 is a graph showing the results of simulating the flow of separated air based on Equation 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiment 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 given the same reference numerals to avoid repeated explanation. Elements not directly related to the present disclosure are not illustrated.

[0012] FIG. 1 is a schematic cross-sectional view of a turbocharger TC. The direction of arrow L shown in FIG. 1 will be described assuming that it is the left side of the turbocharger TC. The direction of arrow R shown in FIG. 1 will be described assuming that it is the right side of the turbocharger TC. As shown in FIG. 1, the turbocharger TC includes a turbocharger body 1. The turbocharger body 1 includes a bearing housing 2. A turbine housing 4 is connected to the left side of the bearing housing 2 by a fastening bolt 3. A compressor housing 100 is connected to the right side of the bearing housing 2 by a fastening bolt 5.

[0013] An accommodation hole 2a is formed in the bearing housing 2. The accommodation hole 2a penetrates in the left-right direction of the turbocharger TC. A bearing 6 is provided in the accommodation hole 2a. In FIG. 1, a full-floating bearing is shown as an example of the bearing 6. However, the bearing 6 may be another radial bearing such as a semi-floating bearing or a rolling bearing. A shaft 7 is rotatably supported by the bearing 6. A turbine impeller 8 is provided at the left end of the shaft 7. The turbine impeller 8 is rotatably accommodated within the turbine housing 4. A compressor impeller 9 (impeller) is provided at the right end of the shaft 7.

[0014] The compressor impeller 9 has a main body 9a. An outer peripheral surface 9b of the main body 9a faces one side of the compressor impeller 9 in the rotational axis direction (hereinafter, simply referred to as the rotational axis direction. The axial direction of the shaft 7, the left-right direction of the turbocharger TC). A back surface 9c faces the other side in the rotational axis direction. A plurality of blades 9d are provided on the outer peripheral surface 9b at intervals in the circumferential direction of the outer peripheral surface 9b. The blades 9d protrude radially from the outer peripheral surface 9b. The compressor impeller 9 is rotatably accommodated in a compressor housing 100. The compressor housing 100 has a first housing member 110 and a second housing member 120. The first housing member 110 and the second housing member 120 will be described in detail later.

[0015] The compressor housing 100 is formed with an intake port 10. The intake port 10 opens to the right side of the turbocharger TC. The intake port 10 is connected to an air cleaner (not shown). When the bearing housing 2 and the compressor housing 100 are connected with the fastening bolts 5, a diffuser passage 11 is formed. The diffuser passage 11 pressurizes the air. The diffuser passage 11 is formed in an annular shape from the inside to the outside in the radial direction (hereinafter simply referred to as the radial direction) of the shaft 7 (compressor impeller 9). The diffuser passage 11 is connected to the intake port 10 via the compressor impeller 9 on the inside in the radial direction.

[0016] Further, a compressor scroll passage 12 is formed inside the compressor housing 100. The compressor scroll passage 12 is annular. The compressor scroll passage 12 is located radially outward of the compressor impeller 9. The compressor scroll passage 12 communicates with an intake port of an engine (not shown). The compressor scroll passage 12 also communicates with a diffuser passage 11. When the compressor impeller 9 rotates, air is sucked into the compressor housing 100 from the intake port 10. The sucked air is accelerated by the action of centrifugal force in the process of flowing between the multiple blades 9d of the compressor impeller 9. The accelerated air is pressurized in the diffuser passage 11 and the compressor scroll passage 12. The pressurized air flows out from a discharge port (not shown) and is led to the intake port of the engine.

[0017] Thus, the turbocharger TC includes a centrifugal compressor C. The centrifugal compressor C includes a compressor housing 100, a compressor impeller 9, and a compressor scroll passage 12.

[0018] An exhaust port 13 is formed in the turbine housing 4. The exhaust port 13 opens to the left side of the turbocharger TC. The exhaust port 13 is connected to an exhaust gas purification device (not shown). In addition, the turbine housing 4 is provided with a flow path 14 and a turbine scroll flow path 15. The turbine scroll flow path 15 is located radially outward of the turbine impeller 8. The flow path 14 is located between the turbine impeller 8 and the turbine scroll flow path 15.

[0019] The turbine scroll passage 15 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 turbine scroll passage 15 also communicates with the above-mentioned passage 14. The exhaust gas introduced from the gas inlet to the turbine scroll passage 15 is introduced to the exhaust port 13 through the passage 14 and between the blades of the turbine impeller 8. The exhaust gas introduced to the exhaust port 13 rotates the turbine impeller 8 during its flow process.

[0020] The rotational force of the turbine impeller 8 is transmitted to the compressor impeller 9 via the shaft 7. As described above, the air is pressurized by the rotational force of the compressor impeller 9 and is led to the intake port of the engine.

[0021] Fig. 2 is an extracted view of the dashed line portion in Fig. 1. Fig. 2 extracts and shows the compressor impeller 9, the compressor housing 100, and a throttle member, which will be described later. As shown in Fig. 2, the first housing member 110 of the compressor housing 100 is located to the right of the second housing member 120 in Fig. 2 (the side away from the bearing housing 2).

[0022] The first housing member 110 has a roughly cylindrical shape. The first housing member 110 has a small diameter portion 110a, a medium diameter portion 110b, and a large diameter portion 110c. The small diameter portion 110a is the furthest from the bearing housing 2. The large diameter portion 110c is the closest to the bearing housing 2. The medium diameter portion 110b is located between the small diameter portion 110a and the large diameter portion 110c. The small diameter portion 110a has a smaller outer diameter than the medium diameter portion 110b. The medium diameter portion 110b has a smaller outer diameter than the large diameter portion 110c. However, the first housing member 110 does not have to have the small diameter portion 110a, the medium diameter portion 110b, and the large diameter portion 110c. For example, the outer diameter may be roughly constant in the direction of the rotation axis.

[0023] A through hole 111 is formed in the first housing member 110. The through hole 111 passes through the first housing member 110 in the rotation axis direction. The through hole 111 passes through the small diameter portion 110a, the medium diameter portion 110b, and the large diameter portion 110c in the rotation axis direction. One end of the through hole 111 is the intake port 10 described above.

[0024] The through hole 111 has a parallel portion 111a and a reduced diameter portion 111b. The parallel portion 111a is located closer to one end of the through hole 111 than the reduced diameter portion 111b. One end of the parallel portion 111a is the intake port 10. The inner diameter of the parallel portion 111a is approximately constant along the axial direction. One end of the reduced diameter portion 111b is continuous with the parallel portion 111a. The inner diameter of the one end of the reduced diameter portion 111b is approximately equal to the inner diameter of the parallel portion 111a. The inner diameter of the reduced diameter portion 111b becomes smaller as it becomes farther away from the parallel portion 111a (as it becomes closer to the second housing member 120).

[0025] A notch 112a is formed in the outer periphery of an end face 112 of the first housing member 110 on the side of the second housing member 120. The notch 112a is, for example, annular.

[0026] An accommodating groove 112b is formed in the end surface 112 of the first housing member 110. The accommodating groove 112b is recessed toward the intake port 10 side (the side away from the second housing member 120) from the end surface 112. The accommodating groove 112b has, for example, a roughly annular shape when viewed from the axial direction. In other words, the accommodating groove 112b is recessed from the inner wall of the through hole 111 toward the outside in the radial direction.

[0027] A bearing hole 112d is formed in a wall surface 112c of the accommodation groove 112b on the intake port 10 side (the small diameter portion 110a side, the side away from the second housing member 120). The bearing hole 112d extends from the wall surface 112c toward the intake port 10 side in parallel to the rotation axis direction. Two bearing holes 112d are provided spaced apart in the rotation direction of the compressor impeller 9 (hereinafter simply referred to as the rotation direction). The two bearing holes 112d are disposed at positions offset by 180 degrees in the rotation direction.

[0028] A through hole 121 is formed in the second housing member 120. The through hole 121 penetrates the second housing member 120 in the rotation axis direction. The inner diameter of the end of the through hole 121 on the first housing member 110 side is approximately equal to the inner diameter of the end of the through hole 111 on the second housing member 120 side. A shroud portion 121a is formed on the inner wall of the through hole 121 in the second housing member 120. The shroud portion 121a faces the compressor impeller 9 from the outside in the radial direction. The inner diameter of the shroud portion 121a increases as it moves away from the first housing member 110. The end of the shroud portion 121a opposite to the first housing member 110 communicates with the diffuser passage 11 described above.

[0029] An accommodating groove 122a is formed in an end face 122 of the second housing member 120 on the first housing member 110 side. The accommodating groove 122a is recessed toward the diffuser flow passage 11 side (the side away from the first housing member 110) from the end face 122. When viewed from the axial direction, the accommodating groove 122a has, for example, a roughly annular shape. In other words, the accommodating groove 122a is recessed radially outward from the inner wall of the through hole 121. The large diameter portion 110c is inserted into the accommodating groove 122a. The end face 112 of the first housing member 110 abuts against the wall surface of the accommodating groove 122a on the diffuser flow passage 11 side.

[0030] The through hole 111 of the first housing member 110 and the through hole 121 of the second housing member 120 form an intake passage 130. The intake passage 130 communicates the intake port 10 and the diffuser passage 11. The compressor impeller 9 is provided in the intake passage 130. The cross-sectional shape of the intake passage 130 (through holes 111, 121) perpendicular to the rotation axis direction is, for example, a circle centered on the rotation axis of the compressor impeller 9. However, the cross-sectional shape of the intake passage 130 is not limited to this. In addition, a seal material (not shown) is disposed in the cutout portion 112a of the first housing member 110. The seal material suppresses the flow rate of air flowing through the gap between the first housing member 110 and the second housing member 120. However, the cutout portion 112a and the seal material are not essential components.

[0031] Fig. 3 is an exploded perspective view of members constituting the link mechanism 200 (throttle mechanism). Of the compressor housing 100, only the first housing member 110 is shown in Fig. 3. As shown in Fig. 3, the link mechanism 200 has the compressor housing 100, a first throttling member 210 (throttle member), a second throttling member 220 (throttle member), a connecting member 230, and a rod 240.

[0032] The first diaphragm member 210 has a curved portion 211. The curved portion 211 is roughly semicircular in shape. Of the curved portion 211, one end face 211a and the other end face 211b in the rotational direction extend parallel to the radial direction and the rotational axis direction. However, the one end face 211a and the other end face 211b may be inclined with respect to the radial direction and the rotational axis direction.

[0033] An arm portion 212 is provided on one end surface 211a side of the curved portion 211. The arm portion 212 extends radially outward from an outer circumferential surface 211c of the curved portion 211. The arm portion 212 also extends in a direction inclined relative to the radial direction (toward the second diaphragm member 220).

[0034] The second diaphragm member 220 has a curved portion 221. The curved portion 221 is roughly semicircular in shape. Of the curved portion 221, one end face 221a and the other end face 221b in the rotational direction extend parallel to the radial direction and the rotational axis direction. However, the one end face 221a and the other end face 221b may be inclined with respect to the radial direction and the rotational axis direction.

[0035] An arm portion 222 is provided on one end surface 221a side of the curved portion 221. The arm portion 222 extends radially outward from an outer circumferential surface 221c of the curved portion 221. The arm portion 222 also extends in a direction inclined relative to the radial direction (toward the first diaphragm member 210).

[0036] The curved portion 211 and the curved portion 221 face each other across the rotation center (intake passage 130) of the compressor impeller 9. One end surface 211a of the curved portion 211 faces the other end surface 221b of the curved portion 221. The other end surface 211b of the curved portion 211 faces one end surface 221a of the curved portion 221.

[0037] The connecting member 230 is located closer to the intake port 10 than the first throttling member 210 and the second throttling member 220. The connecting member 230 has a roughly arc shape. Bearing holes 231, 232 are formed on one end side and the other end side of the connecting member 230 in the rotational direction. The bearing holes 231, 232 open to an end face 233 of the connecting member 230 on the first throttling member 210 and second throttling member 220 side. The bearing holes 231, 232 extend in the rotational axis direction. Here, the bearing holes 231, 232 are configured as non-through holes. However, the bearing holes 231, 232 may pass through the connecting member 230 in the rotational axis direction.

[0038] A rod connecting portion 234 is provided in the connecting member 230 between the bearing holes 231, 232. The rod connecting portion 234 is provided on an end face 235 of the connecting member 230 on the opposite side to the first throttling member 210 and the second throttling member 220. The rod connecting portion 234 protrudes from the end face 235 in the rotation axis direction. The rod connecting portion 234 has, for example, a roughly cylindrical shape.

[0039] The rod 240 has a roughly cylindrical shape. A flat portion 241 is formed at one end of the rod 240. The flat portion 241 extends in a plane direction roughly perpendicular to the rotation axis direction. A bearing hole 242 opens in the flat portion 241. The bearing hole 242 extends in the rotation axis direction. A connecting portion 243 is provided at the other end of the rod 240. The connecting portion 243 has a connecting hole 243a. An actuator, which will be described later, is connected to the connecting portion 243. The bearing hole 242 may be, for example, an elongated hole that is longer than the axial direction of the rod 240 in a direction perpendicular to the rotation axis direction and the axial direction of the rod 240 (left-right direction in FIG. 5, which will be described later).

[0040] A rod large diameter portion 244 is formed in the rod 240 between the flat portion 241 and the connecting portion 243. The outer diameter of the rod large diameter portion 244 is larger than the outer diameter of the rod 240 at a portion continuing to the flat portion 241 side and the connecting portion 243 side relative to the rod large diameter portion 244.

[0041] An insertion hole 113 is formed in the first housing member 110. One end 113a of the insertion hole 113 opens to the outside of the first housing member 110. The insertion hole 113 extends, for example, in a plane perpendicular to the rotation axis direction. The insertion hole 113 is located radially outward of the through hole 111 (intake passage 130). The flat portion 241 side of the rod 240 is inserted into the insertion hole 113. The rod large diameter portion 244 is guided by the inner wall surface of the insertion hole 113 of the first housing member 110. Therefore, movement of the rod 240 is restricted in any direction other than the central axis direction of the insertion hole 113 (the central axis direction of the rod 240).

[0042] The first housing member 110 has an accommodating hole 114 formed therein. The accommodating hole 114 opens to a wall surface 112c of the accommodating groove 112b. The accommodating hole 114 is recessed from the wall surface 112c toward the intake port 10 side (the side away from the second housing member 120). When viewed from the rotation axis direction, the accommodating hole 114 has a roughly arc shape. On the wall surface 112c, the accommodating hole 114 extends in the rotation direction longer than the connecting member 230. The accommodating hole 114 is spaced apart from the bearing holes 231 and 232 in the rotation axis direction. The accommodating hole 114 is located closer to the second housing member 120 side (the first throttle member 210 side) than the insertion hole 113.

[0043] A communication hole 115 is formed in the first housing member 110. The communication hole 115 communicates between the insertion hole 113 and the accommodation hole 114. The communication hole 115 is formed in approximately the middle portion of the accommodation hole 114 in the rotation direction. The communication hole 115 extends approximately parallel to the extension direction of the insertion hole 113. The width of the communication hole 115 in a plane perpendicular to the extension direction of the insertion hole 113 and the rotation axis direction is larger than the outer diameter of the rod connection portion 234 of the coupling member 230. The communication hole 115 is an elongated hole whose width in the extension direction of the insertion hole 113 is larger than the width in a plane perpendicular to the extension direction of the insertion hole 113 and the rotation axis direction.

[0044] The connecting member 230 is accommodated in the accommodating hole 114. The accommodating hole 114 is longer in the rotational direction and has a larger radial width than the connecting member 230. Therefore, inside the accommodating hole 114, the connecting member 230 is allowed to move in a planar direction perpendicular to the rotational axis direction.

[0045] The rod connecting part 234 is inserted from the communicating hole 115 into the insertion hole 113. A bearing hole 242 of the rod 240 inserted into the insertion hole 113 faces the communicating hole 115. The rod connecting part 234 is inserted into (connected to) the bearing hole 242. The rod connecting part 234 is journaled in the bearing hole 242.

[0046] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2. As indicated by the dashed line in Fig. 4, the first throttling member 210 has a connecting shaft portion 213 and a rotating shaft portion 214. The connecting shaft portion 213 and the rotating shaft portion 214 protrude in the direction of the rotating shaft from an end face of the first throttling member 210 on the intake port 10 side (the wall surface 112c side of the accommodating groove 112b). The connecting shaft portion 213 and the rotating shaft portion 214 extend toward the rear of the page in Fig. 4. The rotating shaft portion 214 extends parallel to the connecting shaft portion 213.

[0047] The outer diameter of the connecting shaft portion 213 is smaller than the inner diameter of the bearing hole 231 of the connecting member 230. The connecting shaft portion 213 is inserted into the bearing hole 231. The connecting shaft portion 213 is journaled in the bearing hole 231. The outer diameter of the rotating shaft portion 214 is smaller than the inner diameter of the bearing hole 112d of the first housing member 110. The rotating shaft portion 214 is inserted into one of the bearing holes 112d. The rotating shaft portion 214 is journaled in the bearing hole 112d (see FIG. 2). That is, the rotating shaft portion 214 connects the first diaphragm member 210 and the wall surface 112c that faces the first diaphragm member 210 in the rotation axis direction.

[0048] The second throttling member 220 has a connecting shaft portion 223 and a rotating shaft portion 224. The connecting shaft portion 223 and the rotating shaft portion 224 protrude in the rotation axis direction from an end face of the second throttling member 220 on the intake port 10 side (the wall surface 112c side of the accommodating groove 112b). The connecting shaft portion 223 and the rotating shaft portion 224 extend toward the back of the page in FIG. 4. The rotating shaft portion 224 extends parallel to the connecting shaft portion 223.

[0049] The outer diameter of the connecting shaft portion 223 is smaller than the inner diameter of the bearing hole 232 of the connecting member 230. The connecting shaft portion 223 is inserted into the bearing hole 232. The connecting shaft portion 223 is journaled in the bearing hole 232. The outer diameter of the rotating shaft portion 224 is smaller than the inner diameter of the bearing hole 112d. The rotating shaft portion 224 is inserted into the other bearing hole 112d. The rotating shaft portion 224 is journaled in the bearing hole 112d (see FIG. 2). That is, the rotating shaft portion 224 connects the second diaphragm member 220 and the wall surface 112c that faces the second diaphragm member 220 in the rotation axis direction.

[0050] In this way, the link mechanism 200 is configured as a four-joint link mechanism. The four links (joints) are the first diaphragm member 210, the second diaphragm member 220, the first housing member 110, and the connecting member 230. Since the link mechanism 200 is configured as a four-joint link mechanism, it becomes a limited chain with one degree of freedom and is easy to control.

[0051] Fig. 5 is a first diagram for explaining the operation of link mechanism 200. The following Figs. 5, 6, and 7 show views seen from the intake port 10 side. As shown in Fig. 5, one end of drive shaft 251 of actuator 250 is connected to connecting portion 243 of rod 240.

[0052] In the arrangement shown in Fig. 5, the first throttling member 210 and the second throttling member 220 abut against each other. At this time, as shown in Figs. 2 and 4, a protruding portion 215 which is a radially inner portion of the first throttling member 210 protrudes into the intake passage 130. A protruding portion 225 which is a radially inner portion of the second throttling member 220 protrudes into the intake passage 130. The positions of the first throttling member 210 and the second throttling member 220 at this time are referred to as throttling positions.

[0053] At the throttling position, rotational direction ends 215a, 215b of protrusion 215 abut against rotational direction ends 225a, 225b of protrusion 225. Protrusions 215 and 225 form an annular hole 260. The inner diameter of annular hole 260 is smaller than the inner diameter of the portion of intake passage 130 from which protrusions 215, 225 protrude. The inner diameter of annular hole 260 is smaller than the inner diameter of any portion of intake passage 130, for example.

[0054] Fig. 6 is a second diagram for explaining the operation of link mechanism 200. Fig. 7 is a third diagram for explaining the operation of link mechanism 200. Actuator 250 linearly moves rod 240 in a direction intersecting the rotation axis direction (up and down direction in Figs. 6 and 7). Rod 240 moves upward from the state shown in Fig. 5. The amount of movement of rod 240 in the arrangement of Fig. 7 relative to the arrangement of Fig. 5 is greater than that in Fig. 6.

[0055] When the rod 240 moves, the connecting member 230 also moves upward in Figures 6 and 7 via the rod connecting part 234. At this time, the connecting member 230 is allowed to rotate around the rod connecting part 234. Also, there is a slight play in the inner diameter of the bearing hole 242 of the rod 240 with respect to the outer diameter of the rod connecting part 234. Therefore, the connecting member 230 is allowed to move slightly in a planar direction perpendicular to the rotation axis direction.

[0056] As described above, the link mechanism 200 is a four-bar link mechanism, and the connecting member 230, the first diaphragm member 210, and the second diaphragm member 220 exhibit behavior with one degree of freedom relative to the first housing member 110. Specifically, the connecting member 230 rotates slightly counterclockwise in Figures 6 and 7 while swinging slightly in the left-right direction within the above-mentioned allowable range.

[0057] Of the first diaphragm member 210, the rotating shaft portion 214 is journaled to the first housing member 110, and thus its movement in a planar direction perpendicular to the rotation axis direction is restricted. The connecting shaft portion 213 is journaled to the connecting member 230. Since movement of the connecting member 230 is permitted, the connecting shaft portion 213 is provided so as to be movable in a planar direction perpendicular to the rotation axis direction. As a result, in conjunction with the movement of the connecting member 230, the first diaphragm member 210 rotates in the clockwise direction in FIGS. 6 and 7 around the rotating shaft portion 214 as the center of rotation.

[0058] Similarly, of the second diaphragm member 220, the rotating shaft portion 224 is journaled to the first housing member 110, and thus its movement in a planar direction perpendicular to the rotation axis direction is restricted. The connecting shaft portion 223 is journaled to the connecting member 230. Since the movement of the connecting member 230 is permitted, the connecting shaft portion 223 is provided so as to be movable in a planar direction perpendicular to the rotation axis direction. As a result, in conjunction with the movement of the connecting member 230, the second diaphragm member 220 rotates in the clockwise direction in FIGS. 6 and 7 around the rotating shaft portion 224 as the center of rotation.

[0059] In this way, the first throttling member 210 and the second throttling member 220 move in a direction away from each other in the order of Figs. 6 and 7. The protrusions 215 and 225 move radially outward from the throttling position (retracted position). In the retracted position, for example, the protrusions 215 and 225 are flush with the inner wall surface of the intake passage 130 or are positioned radially outward from the inner wall surface of the intake passage 130. When moving from the retracted position to the throttling position, the first throttling member 210 and the second throttling member 220 approach each other and come into contact with each other in the order of Figs. 7, 6, and 5. In this way, the first throttling member 210 and the second throttling member 220 switch between the throttling position and the retracted position depending on the rotation angle about the rotation shafts 214 and 224 as the rotation center.

[0060] Fig. 8 is an extracted view of the part enclosed by the two-dot chain line in Fig. 2. The following description will be given taking the first throttling member 210 as an example, but the second throttling member 220 has the same configuration (arrangement) as the first throttling member 210. In Fig. 8, the first throttling member 210 is in the throttling position. In the throttling position, the protruding portion 215 of the first throttling member 210 and the protruding portion 225 of the second throttling member 220 protrude most radially inward in the intake passage 130.

[0061] The protrusion 215 of the first throttling member 210 has an opposing surface 215c. The opposing surface 215c faces the leading edge LE of the blade 9d of the compressor impeller 9. The leading edge LE is the upstream end of the blade 9d in the air flow direction. Here, the leading edge LE is inclined relative to the radial direction. The leading edge LE is located on the left side (the side away from the intake port 10, the bearing 6 side) in FIG. 8 as it moves radially outward. However, the leading edge LE may be parallel to the radial direction.

[0062] The outer peripheral end 9e of the leading edge LE is the radially outermost portion of the leading edge LE. Here, the outer peripheral end 9e is located on the leftmost side (the side farthest from the intake port 10, the side of the bearing 6) of the leading edge LE in FIG.

[0063] The inner circumferential end 9f of the leading edge LE is the radially innermost portion of the leading edge LE. Here, the inner circumferential end 9f is located on the right side (the side closest to the intake port 10, the side farther away from the bearing 6) of the leading edge LE in FIG.

[0064] The axial position of the outer circumferential end 9e is to the left of the opposing surface 215c of the protrusion 215 in FIG. 8. The axial position of the inner circumferential end 9f is to the right of the opposing surface 215c of the protrusion 215 in FIG. 8. In other words, the opposing surface 215c is provided between the axial position of the outer circumferential end 9e of the leading edge LE and the axial position of the inner circumferential end 9f of the leading edge LE. This allows the outer circumferential end 9e to be closer to the protrusion 215 even if the leading edge LE has a shape that is inclined with respect to a direction perpendicular to the axial direction.

[0065] 8, the distance (shortest distance, axial distance) between the opposing surface 215c of the protruding portion 215 of the first throttling member 210 and the outer circumferential end 9e of the leading edge LE is defined as a distance LL. The maximum protruding height (height at the throttling position) of the protruding portion 215 protruding from the inner wall surface of the intake passage 130 is defined as a height h max Let us assume that.

[0066] Fig. 9 is a graph showing the relationship between the distance LL and the improvement rate of the adiabatic efficiency. In Fig. 9, the vertical axis indicates the distance LL. The horizontal axis indicates the improvement rate of the adiabatic efficiency. Here, the improvement rate of the adiabatic efficiency indicates the rate at which the adiabatic efficiency is improved (increased) by moving the first throttling member 210 and the second throttling member 220 to their throttling positions, relative to the adiabatic efficiency at the fully open position. At the fully open position, the protruding portion 215 of the first throttling member 210 and the protruding portion 225 of the second throttling member 220 are positioned at the radially outermost position (for example, radially outer than the intake passage 130).

[0067] In addition, in Fig. 9, the air compression ratios of the legends AA, AB, and AC are different from one another. The compression ratio of the legend AA is the lowest, and the compression ratio of the legend AC is the highest. As shown in Fig. 9, the improvement rate of the adiabatic efficiency is higher when the distance LL is smaller, regardless of the compression ratio. In other words, the closer the first throttling member 210 is to the leading edge LE, the higher the improvement rate of the adiabatic efficiency.

[0068] FIG. 10 is a diagram for explaining the range of arrangement of the protruding portion 215 of the first throttle member 210. In FIG. 10, the view is inverted from FIG. 8 in order to make it easier to understand the correspondence with FIG. 11. The air that is throttled by the protruding portion 215 and separated from the inner wall surface of the intake passage 130 flows in the direction of the rotation axis while gradually spreading radially outward as shown by the arrow FL in FIG. 10. At this time, it is known that the relationship of the following mathematical formula 1 holds for the flow of the separated air. Here, the distance X indicates the distance between the opposing surface 215c of the protruding portion 215 and the position where the separated air reattaches to the inner wall surface of the intake passage 130. Re indicates the Reynolds number.

number

[0069] 11 is a graph showing the results of simulating the flow of separated air based on Equation 1. In FIG. 11, the horizontal axis represents the distance x toward the downstream side, with the opposing surface 215c being set at 0, and the height h of the protrusion 215. max The vertical axis represents the ratio r of the height h of the protrusion 215 to the radially inward direction from the inner wall surface of the intake passage 130. max This is the ratio divided by .

[0070] The air flow velocities of the legends BA, BB, and BC are different from one another. The flow velocity of the legend BA is the highest, and the flow velocity of the legend BC is the lowest. As shown in FIG. 11, regardless of the flow velocity, when the x ratio exceeds 4, the air rapidly expands radially outward and flows. On the other hand, when the x ratio is in the range of 4 or less, the height h of the protrusion 215 max The air only spreads radially outward to a range of 10% or less of the

[0071] Therefore, in the link mechanism 200, as shown in FIG. 10, the distance LL between the opposing surface 215c of the protruding portion 215 of the first diaphragm member 210 and the outer circumferential end 9e of the leading edge LE is set to be equal to the height h of the protruding portion 215. max That is, with respect to the opposing surface 215c of the protrusion 215, the leading edge LE is located in a range where the x ratio is 4 or less.

[0072] As a result, the air that has passed through the protruding portion 215 reaches the leading edge LE before it spreads outward in the radial direction. In other words, the air can be compressed by the compressor impeller 9 while the throttling effect of the first throttling member 210 is still sufficient. In addition, since the protruding portion 215 and the leading edge LE have the above-mentioned positional relationship, the flow velocity increases from the radial inner side to the vicinity of the middle position of the leading edge LE, and the inflow angle is improved. As a result, the workload of the compressor impeller 9 that cannot be obtained in the vicinity of the shroud portion 121a can be compensated for by the workload from the radial inner side to the vicinity of the middle position of the leading edge LE.

[0073] Although one embodiment of the present disclosure has been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such an embodiment. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0074] For example, in the above-described embodiment, the diaphragm members include the first diaphragm member 210 and the second diaphragm member 220. However, it is sufficient that at least one of the first diaphragm member 210 and the second diaphragm member 220 is provided. Also, three or more diaphragm members may be provided.

[0075] Moreover, the link mechanism 200 described in the above embodiment is merely one example of the throttling mechanism. The throttling mechanism may be any mechanism as long as it can change the radial position of the throttling member and move it to the throttling position or the retracted position (fully open position).

[0076] In the above-described embodiment, the facing surface 215c is provided between the axial position of the outer circumferential end 9e at the leading edge LE and the axial position of the inner circumferential end 9f at the leading edge LE. In other words, the outer circumferential end 9e and the inner circumferential end 9f are located on opposite sides in the axial direction with the facing surface 215c as the boundary. However, the inner circumferential end 9f may be located on a radial extension of the facing surface 215c. Also, the inner circumferential end 9f may be located closer to the outer circumferential end 9e than the facing surface 215c. [Industrial Applicability]

[0077] The present disclosure can be utilized in centrifugal compressors and superchargers. [Explanation of symbols]

[0078] 9: Compressor impeller (impeller) 9a: Main body 9b: Outer peripheral surface 9d: Blade 9e: Outer peripheral end 9f: Inner peripheral end 130: Intake passage 200: Link mechanism (throttle mechanism) 210: First throttle member (throttle member) 215c: Opposing surface 220: Second throttle member (throttle member) C: Centrifugal compressor LE: Leading edge LL: Distance TC: Turbocharger

Claims

1. An impeller having a main body and a plurality of blades provided on an outer circumferential surface of the main body; an intake passage facing the impeller in a rotational axis direction; a housing that accommodates the impeller, the housing including a first housing member including an intake port, and a second housing member including a shroud portion that faces the impeller from an outer side in a radial direction of the impeller, the inner diameter of the shroud portion increasing as it is separated from the first housing member; a throttling mechanism having a throttling member provided in the intake passage, the throttling member being movable in a radial direction of the impeller and being switchable between a throttling position where it protrudes into the intake passage and a retracted position that is radially outward of the throttling position, the throttling member forming a circular annular hole in the intake passage at the throttling position, wherein a ratio of a distance between an outer circumferential end of a leading edge of the blade and the throttling member divided by a maximum protruding height of the throttling member protruding from an inner wall surface of the intake passage is 4 or less; Equipped with the throttling member includes a first throttling member and a second throttling member, each of the first throttling member and the second throttling member being movable to the throttling position and the retracted position by rotating about a predetermined rotation shaft portion, and at the throttling position, the circular annular hole is formed in the intake passage by the two members, the first throttling member and the second throttling member; Centrifugal compressor.

2. The throttle member has an opposing surface that faces the outer circumferential end and the impeller in the axial direction, The centrifugal compressor according to claim 1 , wherein the opposing surface is provided between a position in the axial direction of the outer circumferential end and a position in the axial direction of an inner circumferential end of the leading edge.

3. The centrifugal compressor according to claim 1 or 2 is provided. Supercharger.

Images