WO2022102329A1

WO2022102329A1 - Supercharger

Info

Publication number: WO2022102329A1
Application number: PCT/JP2021/037942
Authority: WO
Inventors: 勇樹郡司; 亮太崎坂
Original assignee: 株式会社Ihi
Priority date: 2020-11-13
Filing date: 2021-10-13
Publication date: 2022-05-19
Also published as: JP2023182873A

Abstract

This supercharger comprises: a turbine housing; a variable nozzle unit that adjusts the gas flow path area inside the turbine housing; and a sealing member for sealing a gap between the turbine housing and the variable nozzle unit. The sealing member, when viewed from the direction of the rotation axis of a turbine, abuts a cylindrical surface of the turbine housing, on the inner peripheral side thereof, over the entire length thereof, and extends in a C-shape around the cylindrical surface.

Description

Supercharger

This disclosure relates to a turbocharger.

Conventionally, the turbocharger described in Patent Document 1 below is known as a technique in such a field. The turbocharger includes a turbine housing that houses the turbine impeller and a variable nozzle unit that is located inside the turbine housing. The variable nozzle unit drives the nozzle vanes to adjust the flow path area of the gas flowing into the turbine impeller. The gap is sealed by sandwiching a sealing member forming an annular shape when viewed from the rotation axis direction of the turbine impeller in the gap between the turbine housing and the variable nozzle unit.

International Publication No. 2016/159004

In the above turbocharger, the seal member is inserted without a gap between the variable nozzle unit and the turbine housing. When the turbocharger is cooled after the operation is stopped, the temperature of the seal member, which is a component having a large specific surface area, drops faster than that of the turbine housing. Therefore, the seal member shrinks heat faster than the portion of the turbine housing with which the seal member is in contact, and the difference in heat shrinkage from the turbine housing causes thermal stress to be generated in the seal member.

For example, FIG. 8 is an image diagram of a simulation result performed for an example of this type of turbocharger, graph 201 shows a change in temperature of a seal member, and graph 202 shows a change in circumferential stress of a seal member. As shown in FIG. 8, when the turbocharger is stopped at t = t1, the temperature of the seal member decreases. As the temperature decreases, the circumferential stress of the sealing member increases and reaches a peak. In recent years, it has been required to operate the turbocharger in a higher temperature environment than before. In this case, the thermal stress acting on the sealing member as described above becomes large, which may cause damage to the sealing member. Further, in order to prevent such damage to the seal member, it is necessary to select a material having a high breaking strength as the material of the seal member, so that there is also a problem that the range of material selection of the seal member is narrowed.

In view of such a problem, the present disclosure describes a turbocharger that reduces the thermal stress of the sealing member generated during cooling.

The turbocharger according to one aspect of the present disclosure is for sealing the gap between the turbine housing, the variable nozzle unit for driving the nozzle vanes arranged in the gas flow path in the turbine housing, and the turbine housing and the variable nozzle unit. The sealing member is provided with a sealing member, and the sealing member covers the entire inner peripheral side with respect to a predetermined portion which is one of the turbine housing and the variable nozzle unit when viewed from the rotation axis direction of the turbine. It is brought into contact with each other and extends in a C shape around a predetermined portion.

According to the supercharger of the present disclosure, it is possible to reduce the thermal stress of the seal member generated during cooling.

It is sectional drawing of the supercharger of embodiment. It is sectional drawing which enlarges and shows the vicinity of the seal member of the supercharger of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. (A) is a plan view of the seal member, (b) is a sectional view thereof IVb-IVb, and (c) is a sectional view showing elastic deformation in the sectional view of the seal member. It is an image diagram of the simulation result by the present inventors. (A) to (d) are sectional views which show the modification of the seal member. It is sectional drawing which shows the modification of the supercharger. It is an image diagram of the simulation result by the present inventors.

The outer peripheral side of the seal member may be in contact with the other of the turbine housing or the variable nozzle unit over the entire length. Further, the high pressure part and the low pressure part of the turbine are connected by a gap, the gap is divided into the high pressure part side and the low pressure part side by the seal member, and the cross section of the seal member has a shape having an opening open to the high pressure part side. You may do it.

The seal member may have a shape in which the curvature is the minimum at the center of the extending direction and the curvature increases as it approaches both ends in the extending direction when it is removed from the turbine housing and the variable nozzle unit.

Hereinafter, embodiments of the variable capacity turbocharger of the present disclosure will be described with reference to the drawings. In each drawing, the characteristics of the components may be exaggerated and depicted, so the dimensional ratio of each part on the drawing does not necessarily match the actual one.

The variable capacity turbocharger 1 shown in FIG. 1 is applied to, for example, an internal combustion engine of a ship or a vehicle. As shown in FIG. 1, the variable capacity turbocharger 1 includes a turbine 2 and a compressor 3. The turbine 2 includes a turbine housing 4 and a turbine impeller 6 housed in the turbine housing 4. The turbine housing 4 has a scroll flow path 16 extending in the circumferential direction around the turbine impeller 6. The compressor 3 includes a compressor housing 5 and a compressor impeller 7 housed in the compressor housing 5. The compressor housing 5 has a scroll flow path 17 extending in the circumferential direction around the compressor impeller 7.

The turbine impeller 6 is provided at one end of the rotating shaft 14, and the compressor impeller 7 is provided at the other end of the rotating shaft 14. A bearing housing 13 is provided between the turbine housing 4 and the compressor housing 5. The rotating shaft 14 is rotatably supported by the bearing housing 13 via the bearing 15, and the rotating shaft 14, the turbine impeller 6 and the compressor impeller 7 rotate around the rotating axis H as an integral rotating body 12.

The turbine housing 4 is provided with an exhaust gas inlet (not shown) and an exhaust gas outlet 10. Exhaust gas (fluid) discharged from an internal combustion engine (not shown) flows into the turbine housing 4 through the exhaust gas inlet, flows into the turbine impeller 6 through the scroll flow path 16, and rotates the turbine impeller 6. Let me. After that, the exhaust gas flows out of the turbine housing 4 through the exhaust gas outlet 10.

The compressor housing 5 is provided with a suction port 9 and a discharge port (not shown). When the turbine impeller 6 rotates as described above, the compressor impeller 7 rotates via the rotating shaft 14. The rotating compressor impeller 7 sucks in external air through the suction port 9. This air passes through the compressor impeller 7 and the scroll flow path 17, is compressed, and is discharged from the discharge port. The compressed air discharged from the discharge port is supplied to the above-mentioned internal combustion engine.

In the following description, when the terms "axial direction", "radial direction", "circumferential direction", etc. are simply used, they mean the rotation axis direction, the rotation radial direction, and the rotation circumferential direction of the turbine impeller 6, respectively. Further, when the terms "upstream" and "downstream" are used, they mean the upstream and downstream of the exhaust gas in the scroll flow path 16.

The turbine 2 will be further described with reference to FIGS. 1 to 4. The turbine 2 is a variable displacement turbine, and a movable nozzle vane 23 is provided in the gas inflow path 21 connecting the scroll flow path 16 and the turbine impeller 6. A plurality of nozzle vanes 23 are arranged on the circumference centered on the rotation axis H, and each nozzle vane 23 rotates around an axis parallel to the rotation axis H. By rotating the nozzle vane 23 as described above, the cross-sectional area of the gas flow path is optimally adjusted according to the flow rate of the exhaust gas introduced into the turbine 2.

Therefore, the turbine 2 is provided with a variable nozzle unit 25 for driving the nozzle vane 23. The variable nozzle unit 25 is fitted inside the turbine housing 4, and is sandwiched and fixed between the turbine housing 4 and the bearing housing 13. The variable nozzle unit 25 has the nozzle vane 23, and a first nozzle ring 31 and a second nozzle ring 32 that sandwich the nozzle vane 23 in the axial direction. The first nozzle ring 31 and the second nozzle ring 32 each form a ring shape surrounding the turbine impeller 6 in the circumferential direction.

The region sandwiched between the first nozzle ring 31 and the second nozzle ring 32 constitutes the gas inflow path 21 described above. The rotation shaft 23a of each nozzle vane 23 is rotatably inserted into the first nozzle ring 31, and the first nozzle ring 31 supports each nozzle vane 23 in a cantilever manner. The first nozzle ring 31 and the second nozzle ring 32 are connected by a plurality of connecting pins 35 extending in the axial direction. By manufacturing the connecting pin 35 with high-precision dimensions, the axial dimensional accuracy of the gas inflow path 21 is ensured.

The variable nozzle unit 25 has a driving force transmission unit 27, and the driving force from the outside of the turbine 2 is transmitted to the nozzle vane 23 by the driving force transmission unit 27. The driving force transmission unit 27 is housed in a space between the first nozzle ring 31 and the bearing housing 13. When the driving force from the outside of the turbine 2 is input to the driving force transmission unit 27, the rotation shaft 23a of each nozzle vane 23 is synchronously rotated by a predetermined mechanism, and each nozzle vane 23 is synchronously rotated. ..

Next, the arrangement of the variable nozzle unit 25 in the turbine housing 4 will be described. The shroud 41 covers the turbine impeller 6 in the circumferential direction and is formed as a part of the inner peripheral surface of the turbine housing 4. The second nozzle ring 32 of the variable nozzle unit 25 is fitted at a position radially outside the shroud 41. The second nozzle ring 32 faces the scroll flow path 16, and the second nozzle ring 32 forms a part of the inner wall of the scroll flow path 16.

There is a gap G between the second nozzle ring 32 and the turbine housing 4. The gap G connects the scroll flow path 16 and the downstream portion 21a of the gas inflow path 21 (near the inlet of the turbine impeller 6). Since the scroll flow path 16 (high pressure portion) has a higher pressure than the downstream portion 21a (low pressure portion) of the gas inflow path 21, the exhaust gas of the scroll flow path 16 may leak to the downstream portion of the gas inflow path 21 through the gap G. There is. An annular seal member 45 is installed in order to suppress such an exhaust gas leak, and the seal member 45 seals the gap G as a gasket.

A step portion 47 is formed on the inner peripheral edge of the second nozzle ring 32 in order to install the seal member 45. The step portion 47 has a step side surface 49 and a step bottom surface 51, the step side surface 49 forms a cylindrical surface having the rotation axis H as a cylindrical axis, and the step bottom surface 51 is located in a plane orthogonal to the rotation axis H. do. On the turbine housing 4 side, a cylindrical surface 53 is formed at a position on the back surface side of the shroud 41. The cylindrical surface 53 is a cylindrical surface facing the step side surface 49 and having the rotation axis H as the cylindrical axis. The seal member 45 is radially sandwiched between the step side surface 49 and the cylindrical surface 53. Further, the seal member 45 is abutted against the step bottom surface 51 and is supported in the axial direction.

With reference to FIG. 3, the seal member 45 in a state of being assembled to the turbine 2 will be described. When the seal member 45 in this state is viewed from the axial direction (viewed from the line of sight in the rotation axis H direction), the seal member 45 has the inner peripheral side in contact with the cylindrical surface 53 of the turbine housing 4 over the entire length. The seal member 45 extends in a C shape around the cylindrical surface 53 along a virtual circumference centered on the rotation axis H. That is, when viewed from the axial direction, the seal member 45 has a shape in which a discontinuous portion 45s in the circumferential direction is provided at one place with respect to the annulus. In other words, the seal member 45 has a shape in which a long member is curved so that both end faces 45t face each other. When viewed from the axial direction, the seal member 45 has a C-shape in which one part of the annulus is separated in the circumferential direction, and the end faces 45t in the circumferential direction of the seal member 45 have a slight gap (non-existence). The continuous portion 45s) is opened to face each other. Further, the seal member 45 has the outer peripheral side in contact with the step side surface 49 of the variable nozzle unit 25 over the entire length. In order to make it easier to understand the characteristics, the size of the discontinuous portion 45s drawn in the drawing in the circumferential direction is relatively large, but the size of the discontinuous portion 45s in the circumferential direction may be extremely small.

The single seal member 45 in a state of being removed from the turbine 2 will be described. FIG. 4A shows a state in which the single seal member 45 removed from the turbine 2 is viewed from the axial direction by a solid line. For comparison, the seal member 45 in the state of being assembled to the turbine 2 is shown by a two-dot chain line in the figure. The seal member 45 (solid line) removed from the turbine 2 has a slightly wider discontinuous portion 45s between the end faces 45t than the state attached to the turbine 2 (dashed-dotted line). .. In this state, the angle (angle α in the figure) at which both end faces 45t are open about the rotation axis H is, for example, 20 ° or less. Further, the seal member 45 removed from the turbine 2 has the smallest curvature at the center 45p in the extending direction, and the curvature gradually increases as it approaches the both end faces 45t in the extending direction.

As shown in FIGS. 4 (b) and 4 (c), the cross section of the seal member 45 is V-shaped. The seal member 45 exerts an elastic force in a direction in which the

ends

45a and 45a of the V-shaped cross section are spaced apart from each other. Then, the seal member 45 assembled to the turbine 2 exerts an urging force in the direction of expanding the radial distance between the step side surface 49 and the columnar surface 53 with the above elastic force. Due to this urging force, the seal member 45 comes into close contact with the step side surface 49 and the cylindrical surface 53. Since the sealing member 45 exists so as to partition the high pressure portion side (scroll flow path 16 side) and the low pressure portion side (downstream portion 21a side of the gas inflow path 21) of the gap G, the gap G is sealed and the exhaust gas is exhausted. Leakage is suppressed.

Further, in the turbocharger 1, where the dimension of the gap G fluctuates according to the temperature of the turbine 2, the sealing member 45 elastically deforms as described above to follow the dimensional fluctuation of the gap G, and the sealing property of the gap G is improved. Be maintained. According to the seal member 45, the sealing property is slightly sacrificed due to the discontinuous portion 45s as compared with the annular sealing member as described in Patent Document 1, for example.

When such a sealing member 45 is assembled to the turbine 2, it is inserted into the gap G in a state of being elastically deformed into a shape along the virtual circumference when viewed from the axial direction, and the state shown in FIG. 3 described above is obtained. When the seal member 45 is assembled to the turbine 2, the seal member 45 is press-fitted into the step side surface 49 of the variable nozzle unit 25, and the seal member 45 is further press-fitted into the cylindrical surface 53 to form the variable nozzle unit 25 and the turbine housing 4. And are assembled.

As described above, the gap G connects the high pressure portion (scroll flow path 16) and the low pressure portion (downstream portion 21a of the gas inflow path 21) of the turbine 2. The seal member 45 is arranged so as to cross the connection path between the high pressure portion side and the low pressure portion side, thereby partitioning the gap G into the high pressure portion side and the low pressure portion side. The cross-sectional shape of the seal member 45 is a V-shape having an opening 45b opened on the high pressure portion side (scroll flow path 16 side). According to this cross-sectional shape, the seal member 45 receives a force in the direction in which the opening width of the opening 45b is further opened by the pressure from the high pressure portion side. That is, it receives a force in a direction in which the distance between both ends 45a and 45a of the seal member 45 increases. Then, since both

end portions

45a and 45a are pressed more strongly against the step side surface 49 and the columnar surface 53, the effect of suppressing the leakage of the exhaust gas is further enhanced.

The action and effect of the supercharger 1 provided with the above-mentioned sealing member 45 will be described. When the turbocharger 1 is cooled after the operation is stopped, the temperature of the seal member 45, which is a component having a large specific surface area, drops faster than that of the turbine housing 4. Therefore, the seal member 45 heat-shrinks faster than the turbine housing 4, and thermal stress is generated in the seal member 45 due to the difference in heat shrinkage from the turbine housing 4. Here, since the seal member 45 is not an annular shape but has a shape having a discontinuous portion 45s as described above, a part of the heat shrinkage difference between the seal member 45 and the turbine housing 4 is the expansion / contraction of the discontinuous portion 45s. Is absorbed by. As a result, the thermal stress generated in the seal member 45 when the turbocharger 1 is cooled is reduced.

FIG. 5 is an image diagram of the result of simulating the distribution of the circumferential stress of the seal member 45 generated when the temperature of the turbocharger 1 is raised by using the turbocharger model equivalent to the simulation of FIG. Graph 101 in the figure shows the distribution of the circumferential stress of the seal member 45 generated when the temperature of the supercharger 1 rises, and graph 102 in the figure shows the circumferential stress of the seal member 45 generated when the temperature of the supercharger 1 drops. Is the distribution of. The horizontal axis of the graph indicates the circumferential position of the seal member 45, and the position of the discontinuous portion 45s is the 0 ° position. Comparing the result of FIG. 8 with the graph 102, it was confirmed that the circumferential stress of the seal member 45 during cooling of the turbocharger 1 was lower than that of the result of FIG.

Further, when the seal member 45 is assembled to the turbine 2, the seal member 45 not only brings the inner peripheral side into contact with the cylindrical surface 53 of the turbine housing 4 over the entire length, but also brings the outer peripheral side over the entire length. The variable nozzle unit 25 is brought into contact with the step side surface 49 and inserted into the gap G. As a result, the seal member 45 is fitted into the gap G in a state in which the discontinuous portion 45s is deformed so as to be reduced in the circumferential direction. Then, by reducing the discontinuous portion 45s in this way, the reduction in the sealing property of the sealing member 45 can be suppressed.

Further, as described with reference to FIG. 4A, the sealing member 45 in a state of being removed from the turbine 2 has the smallest curvature at the center 45p in the extending direction when viewed from the axial direction, and both end faces in the extending direction. It has a shape in which the curvature gradually increases as it approaches 45t. When the seal member 45 having this shape is assembled to the turbine 2, the change in curvature at the center 45p is the largest, and the change in curvature becomes smaller as the both end faces 45t are approached, so that the seal member 45 approaches a perfect circle along the gap G. be able to.

This disclosure can be carried out in various forms with various changes and improvements based on the knowledge of those skilled in the art, including the above-mentioned embodiment. Further, it is also possible to configure the following modification by utilizing the technical matters described in the above-described embodiment. The configurations of the embodiment and the following modifications may be appropriately combined and used.

The cross-sectional shape of the seal member 45 is not limited to that of FIG. That is, instead of the seal member 45, the seal member 55 having a cross-sectional shape as shown in FIGS. 6A to 6D may be adopted. In any of the cross-sectional shapes of FIGS. 6A to 6D, the seal member 55 has an opening 55e open to the high pressure portion side.

In order to bring the seal member 55 into close contact with both the step side surface 49 and the cylindrical surface 53, the seal member 55 is press-fitted into the columnar surface 53 of the turbine housing 4 and also press-fitted into the step side surface 49 of the second nozzle ring 32. There is a need. In view of this assembly method, the cross-sectional shape of the seal member 55 may be as shown in FIG. 6A. That is, of the

ends

55a and 55b in the cross section of the seal member 55, the radial inner end 55b may be curved toward the radial outer side. According to this configuration, when the seal member 55 is press-fitted into the cylindrical surface 53 of the turbine housing 4, the end portion 55b of the seal member 55 smoothly slides on the cylindrical surface 53, and the seal member 55 is smoothly inserted. To.

Further, for the same reason, the cross-sectional shape of the seal member 55 may be as shown in FIG. 6 (b). That is, the cross section of the seal member 55 in FIG. 6B has an S shape as a whole, and the radial inner portion 55c is curved so as to be convex toward the turbine housing 4 side, and the radial outer portion. At 55d, it is curved so as to be convex toward the variable nozzle unit 25 side. According to this configuration, the seal member 55 is smoothly press-fitted into both the cylindrical surface 53 of the turbine housing 4 and the step side surface 49 of the second nozzle ring 32.

Further, the cross-sectional shape of the seal member 55 may be as shown in FIG. 6 (c). That is, the cross section of the seal member 55 in FIG. 6C has a portion extending in the axial direction along the step side surface 49 and the columnar surface 53 and a portion extending in the radial direction along the step bottom surface 51. It has a U-shape with. Further, for example, as shown in FIG. 6D, the cross-sectional shape may be a shape in which a plurality of V-shaped portions (two steps in the example of the figure) are arranged in the radial direction.

Further, as shown in FIG. 7, the inner peripheral edge of the second nozzle ring 32 may extend toward the exhaust gas outlet 10 side to form the shroud 41. In this case, the gap G connects the scroll flow path 16 (high pressure portion) and the exhaust gas outlet 10 (low pressure portion). A seal member 45 is installed in the gap G, and the seal member 45 partitions the gap G between the scroll flow path 16 side and the exhaust gas outlet 10 side. The seal member 45 is installed so that the opening 45b faces the high pressure side. Further, the seal member 45 is attached in a direction in which the inner peripheral side is brought into contact with the second nozzle ring 32 over the entire length, the outer peripheral side is brought into contact with the turbine housing 4 over the entire length, and the gap G is expanded in the radial direction. Demonstrate power. Even in such a sealing member 45, the presence of the discontinuous portion 45s reduces the thermal stress generated during cooling.

1 Supercharger 2 Turbine 4 Turbine housing 25

Variable nozzle unit

45, 55 Seal member 45t End face 45p Center 45b, 55e Opening 49 Step side 53 Cylindrical surface G Gap H Rotation axis

Claims

Turbine housing and
A variable nozzle unit that drives a nozzle vane arranged in the gas flow path in the turbine housing, and
A sealing member for sealing the gap between the turbine housing and the variable nozzle unit is provided.
The seal member is brought into contact with a predetermined portion, which is one of the turbine housing and the variable nozzle unit, when viewed from the direction of the rotation axis of the turbine, with the inner peripheral side in contact with the predetermined portion over the entire length. A turbocharger that extends in a C shape around the site.
The supercharger according to claim 1, wherein the outer peripheral side of the seal member is in contact with the other of the turbine housing or the variable nozzle unit over the entire length.
The high pressure part and the low pressure part of the turbine are connected by the gap, and the high pressure part and the low pressure part are connected by the gap.
The gap is divided into a high pressure portion side and a low pressure portion side by the seal member, and the gap is divided into a high pressure portion side and a low pressure portion side.
The supercharger according to claim 1 or 2, wherein the cross section of the seal member has a shape having an opening opened on the high pressure portion side.
The seal member is
Any one of claims 1 to 3, which has a shape in which the curvature is the minimum at the center of the extending direction and the curvature increases as it approaches both ends of the extending direction when it is removed from the turbine housing and the variable nozzle unit. The supercharger described in item 1.