KR20210104151A - Casing of a supercharger and a supercharger provided therewith - Google Patents

Abstract

An object of the present invention is to provide a casing of a supercharger having a bypass tube having a simple structure and applicable to a small supercharger having a limited layout, and a supercharger having the same. Casing of the supercharger 1 in which the turbine 30 driven by the exhaust gas which flows through the exhaust gas flow path 12 is formed and the exhaust gas discharged|emitted from an internal combustion engine flows, the casing of the supercharger 1 is accommodated. As (10), a bypass pipe 50 for communicating the exhaust gas flow path 12 on the exhaust gas inlet 12A side and the exhaust gas flow path 12 on the exhaust gas outlet 12B side without interposing the turbine 30 ), the bypass pipe 50 is connected to the exhaust gas inlet 12A side, and a straight pipe 52 having a straight flow path, the straight pipe 52 and the exhaust gas outlet 12B side It is composed of an elbow tube 54 having a flow path that is connected and bent.

Description

Casing of a supercharger and a supercharger provided therewith

The present disclosure relates to a casing of a supercharger and a supercharger provided therewith.

It is calculated|required by the internal combustion engine for ships, the internal combustion engine for power generation, etc. (for example, a diesel engine) to improve the performance at the time of operation|moving at a low load. In order to improve the performance when operating at a low load, it is preferable to set a high boost pressure of a supercharger mounted on the internal combustion engine. However, when the internal combustion engine operates at a high load, the boost pressure becomes too high. Therefore, when the internal combustion engine operates under a high load and the amount of exhaust gas is large, a so-called exhaust gas bypass system has been put into practical use by allowing the exhaust gas to bypass the turbocharger turbine to suppress an excessive increase in the supercharge pressure.

As a supercharger to which the exhaust gas bypass system is employ|adopted, there exists a supercharger currently disclosed by patent document 1, for example. According to this supercharger, it is comprised so that exhaust gas may bypass a turbine by the U-shaped bypass pipe in which the on-off valve was formed.

Moreover, as another example of the supercharger to which the exhaust gas bypass system is employ|adopted, there exists a supercharger currently disclosed by patent document 2, for example. According to this supercharger, by connecting pipes cut at an angle, the exhaust gas is configured to bypass the turbine by a pipe (so-called shrimp pipe) having an arc shape as a whole.

Japanese Patent No. 6165564 Japanese Patent Laid-Open No. 2013-124626

However, in the U-shaped bypass tube of the supercharger disclosed in Patent Document 1, a predetermined space must be secured in order to form a two-point bent portion, and it is difficult to apply it to a small supercharger having restrictions on the layout. Moreover, even if it is applied to a small-sized supercharger, it may be difficult to secure the flow path area between the outlet end of the bypass pipe and the connection part of the casing due to the shape of the casing and the relationship with other parts.

Moreover, in the bypass pipe of the supercharger disclosed by patent document 2, the time and cost required for manufacture may increase on the structure.

The present disclosure has been made in view of such circumstances, and can be applied to a small supercharger having a limited layout, and has a simple structure for the purpose of providing a casing of a supercharger having a bypass tube and a supercharger having the same do.

In order to solve the said subject, the casing of the supercharger of this indication, and the supercharger provided with the same employ|adopt the following means.

That is, the casing of the supercharger according to one aspect of the present disclosure forms an exhaust gas flow path through which the exhaust gas discharged from the internal combustion engine flows, and a turbine driven by the exhaust gas flowing through the exhaust gas flow path is accommodated. A casing of a supercharger used as a turbocharger, comprising: a bypass pipe for communicating the exhaust gas flow path on the exhaust gas inlet side and the exhaust gas flow path on the exhaust gas outlet side without interposing the turbine, wherein the bypass pipe includes the exhaust gas It is composed of a straight pipe connected to the inlet side and having a straight flow path, and an elbow tube connected to the straight pipe and the exhaust gas outlet side and having a curved flow path.

According to the casing of the supercharger according to the present aspect, since the bending portion formed in the bypass pipe is made at one point (only the bending portion of the elbow tube), the number of bending portions can be reduced compared to the conventional structure, and in a small supercharger with restrictions on layout can be applied.

Moreover, since the bypass pipe has a simple structure constituted by two members (a straight pipe and an elbow pipe), the time and cost required for production can be suppressed.

Further, in the casing of the supercharger according to an aspect of the present disclosure, the elbow tube has a substantially circular cross section along the axis, and the shape of the connection passage for communicating the connection portion with the elbow tube and the exhaust gas passageway is , is changing from the substantially circular shape to a flat shape while keeping the flow path area substantially constant.

According to the casing of the supercharger according to the present aspect, the connecting flow path changes from a substantially circular shape to a flat shape in conformity with the elbow shape while maintaining the flow path area substantially constant. In this way, for example, even when there is a restriction on dimensions in a predetermined direction due to the shape of the casing on the exhaust gas outlet side or relation with other components, it is possible to secure the flow path area by setting it to a flat shape that becomes thinner in the predetermined direction.

Moreover, in the casing of the supercharger which concerns on one aspect of this indication, the said connection flow path is formed by casting.

According to the casing of the supercharger according to this aspect, it is possible to easily form a connection flow path having a complicated shape.

Moreover, the casing of the supercharger which concerns on one aspect of this indication WHEREIN: The said bypass pipe is equipped with the on-off valve by which opening and closing of a valve is controlled by a signal from the outside.

According to the casing of the supercharger which concerns on this aspect, the opening/closing state of the on-off valve formed in the bypass pipe is controlled by the signal transmitted from the control part of the internal combustion engine in which the supercharger is mounted, for example. Thereby, it is possible to control the flow rate of the exhaust gas flowing through the bypass pipe in accordance with the specifications and conditions of the internal combustion engine.

Moreover, in the casing of the supercharger which concerns on one aspect of this indication, the said straight pipe is arrange|positioned so that an axial direction and the inflow direction of the said exhaust gas flowing in from the said exhaust gas inlet may substantially correspond.

According to the casing of the supercharger which concerns on this aspect, the exhaust gas which flowed in from the exhaust gas inlet is guided to the bypass pipe without being turned. For this reason, the pressure loss of the exhaust gas guide|induced to the bypass pipe can be suppressed.

Moreover, the casing of the supercharger which concerns on one aspect of this indication WHEREIN: The said straight pipe is provided with the expansion-contraction part which expands and contracts in an axial direction.

According to the casing of the supercharger according to the present aspect, since the straight pipe is expandable and contractible in the axial direction, it is possible to absorb the thermal expansion and thermal contraction generated in the bypass pipe by the circulation of the exhaust gas.

Moreover, when the on-off valve is provided in the bypass pipe, it is preferable that the expansion-contraction part is provided in the downstream side of the on-off valve in the flow direction of exhaust gas.

In addition, the casing of the supercharger according to an aspect of the present disclosure forms an exhaust gas flow path through which the exhaust gas discharged from the internal combustion engine flows, and a turbine driven by the exhaust gas flowing through the exhaust gas flow path. A casing of a supercharger accommodated, comprising a bypass pipe for communicating the exhaust gas flow path on the exhaust gas inlet side and the exhaust gas flow path on the exhaust gas outlet side without interposing the turbine, wherein the bypass pipe has an axis line The cross-sectional area along the cross-section becomes substantially circular, and the connection passage for communicating the connecting portion with the bypass pipe and the exhaust gas flow passage changes from the substantially circular shape to a flat shape while maintaining a substantially constant cross-sectional area.

According to the casing of the supercharger according to this aspect, the connection passage for communicating the connection part with the bypass pipe and the exhaust gas flow passage through which exhaust gas flows has a shape of the flow passage matching the bypass pipe while maintaining the flow passage area substantially constant. It is changing from a substantially circular shape to a flat shape. In this way, for example, even when there is a restriction on dimensions in a predetermined direction due to the shape of the casing on the exhaust gas outlet side or relation with other components, it is possible to secure the flow path area by setting it to a flat shape that becomes thinner in the predetermined direction.

Moreover, the supercharger which concerns on one aspect of this indication is equipped with the casing of the above-mentioned supercharger, and the said turbine driven by the exhaust gas discharged|emitted from the internal combustion engine.

According to the present disclosure, it is possible to provide a casing of a supercharger having a bypass tube having a simple structure, which can be applied to a small supercharger having a limited layout, and a supercharger having the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal sectional view of the casing of the supercharger which concerns on one Embodiment of this indication, and the supercharger provided with the same.
Fig. 2 is a partially enlarged view of section A shown in Fig. 1 , and is a perspective view showing the shape of an outlet-side connection passage.

Hereinafter, the casing of the supercharger which concerns on one Embodiment of this indication, and the supercharger provided with the same are demonstrated using FIG. 1 and FIG. 2 .

First, the structure of the casing 10 and the supercharger 1 provided with the casing 10 is demonstrated.

As shown in FIG. 1 , the supercharger 1 is configured to forcibly feed air with high density into the combustion chamber of the internal combustion engine by compressing combustion air supplied to an internal combustion engine mounted on a ship or the like, for example. The casing 10 which concerns on this embodiment is employ|adopted especially for a small supercharger, and it is preferable.

The supercharger 1 includes a turbine 30 driven by exhaust gas discharged from an internal combustion engine (not shown), a rotor shaft 33 rotationally driven around an axis X by the turbine 30, and housing these The casing 10 is provided to form an exhaust gas flow path (exhaust gas flow path 12) together with the exhaust gas flow path.

The turbine 30 becomes an axial flow turbine provided with the turbine disk 31 with which the rotor blade 32 was attached, and the nozzle ring 34 with which the guide vane 34a was attached.

The rotor blade 32 is arranged so as to be close to the downstream end of the guide vane 34a (to be described later) along the axis X direction in the exhaust gas flow passage 12 , and is formed at one end of the rotor shaft 33 . A plurality of sheets are attached to the periphery of the disk-shaped turbine disk 31 .

In addition, in the flow direction of the exhaust gas, the exhaust gas flow path 12 on the upstream side of the rotor blade 32 is shown by the code|symbol 12a, and the exhaust gas flow path 12 downstream of the rotor blade 32 is represented by the code|symbol 12b.

The nozzle ring 34 includes a cylindrical outer ring 34c extending in the axis X direction, an inner ring 34b having a smaller diameter than the outer ring 34c, and an outer ring 34c, A guide vane 34a mounted between the inner peripheral side rings 34b is provided.

The nozzle ring 34 is attached to the casing 10 so that the outer circumferential side ring 34c and the inner circumferential side ring 34b become a part of the wall portion forming the exhaust gas flow path 12a along the axis X direction. At this time, the casing 10 is divided|segmented back and front of the nozzle ring 34 along the axis line X direction.

A plurality of guide vanes 34a are mounted in the circumferential direction of the axis X between the inner peripheral wall of the outer peripheral side ring 34c and the outer peripheral wall of the inner peripheral side ring 34b.

The guide vane 34a is a blade shape for appropriately guiding the exhaust gas toward the rotor blade 32 by adjusting the flow rate and direction of the exhaust gas flowing toward the rotor blade 32 side in the exhaust gas flow path 12a. become absent

As for the turbine 30, the high-temperature exhaust gas which has passed through the guide vane 34a passes through the rotor blade 32 and expands, so that the turbine disk 31 and the rotor shaft 33 are rotated. In addition, an impeller (not shown) of a compressor (not shown) is formed at the other end of the rotor shaft 33, and when the rotor shaft 33 is rotationally driven, the impeller is rotationally driven and air is compressed.

The casing 10 has a gas inlet (exhaust gas inlet) 12A formed in the lower part and opened downward, and a gas outlet (exhaust gas outlet) 12B formed in the upper part and opened upward, The exhaust gas flow path 12 (12a, 12b, 12c) which communicates with the gas inlet 12A and the gas outlet 12B via the 30 is formed, and the casing 10 is the turbine 30 And it is accommodated so as to surround a part of the rotor shaft 33 .

In addition, the casing 10 is a flow path (by) for communicating the exhaust gas flow path 12a on the gas inlet 12A side and the exhaust gas flow path 12c on the gas outlet 12B side without interposing the turbine 30. The bypass pipe 50 which forms the pass flow path 51 is provided.

The bypass pipe 50 has an L-shape toward the gas outlet 12B side from the gas inlet 12A side when viewed from the side as shown in FIG. It is provided with the straight pipe|tube 52 which has and one elbow tube 54 which has the flow path (flexion flow path 55) whose axis line was bent substantially at right angles. Thereby, since the bent part formed in the bypass pipe 50 can be made into 1 point, it can apply to the small-sized supercharger 1 with a restriction|limiting in a layout. Moreover, the bypass pipe 50 can be set as the simple structure comprised by the two members (the straight pipe 52 and the elbow pipe 54).

As for the straight pipe 52 and the elbow tube 54, it is preferable that the flow path shape along an axis line becomes a substantially circular shape.

The straight pipe 52 is connected at one end to the casing 10 which forms the exhaust gas flow path 12a on the side of the gas inlet 12A.

In the casing 10 of the portion to which the straight pipe 52 is connected, an inlet-side connection flow passage 16 that communicates with the exhaust gas flow passage 12a and the outside of the casing 10 is formed. The inlet-side connection flow path 16 has an axial line in the inflow direction of the exhaust gas flowing in from the gas inlet 12A (arrow Gi in the drawing).

The straight pipe 52 is arranged with respect to the casing 10 so that the axis of the straight flow path 53 is located on the extension of the axis of the inlet-side connection flow path 16 . That is, the axial direction of the linear flow path 53 coincides with the inflow direction of the exhaust gas flowing in from the gas inlet 12A. Thereby, the exhaust gas flowing in from the gas inlet 12A is guided to the bypass flow passage 51 without being diverted.

The elbow tube 54 has one end connected to the other end of the straight pipe 52 (an end different from the end connected to the casing 10). Moreover, the elbow tube 54 is connected to the casing 10 in which the other end forms the exhaust gas flow path 12c on the side of the gas outlet 12B.

In the casing 10 of the portion to which the elbow tube 54 is connected, an outlet-side connection flow path (connection flow path) 18 that communicates with the outside of the casing 10 and the exhaust gas flow path 12c is formed.

As described above, since the elbow 54 has an axis smoothly bent at a substantially right angle, the axial direction of the outlet-side connection flow path 18 and the axial direction of the straight flow path 53 are substantially orthogonal to each other.

As shown in FIGS. 1 and 2 , the shape of the outlet-side connection flow path 18 is a substantially circular shape that matches the flow path shape of the elbow pipe 54 at the connection portion 14 with the elbow pipe 54 . have. Moreover, the shape of the outlet side connection flow path 18 is changing from the connection part 14 side toward the exhaust gas flow path 12c side to the flat shape in which the width direction was expanded and the height direction was reduced.

At this time, from the side of the connection part 14 toward the side of the exhaust gas flow path 12c, the shape is changed so that the flow path area of the outlet side connection flow path 18 may be maintained substantially constant. Thereby, for example, even if there is a restriction on the dimension in the height direction due to the shape of the casing 10 on the gas outlet 12B side or relation with other parts, the flow path area is reduced by making the shape thinner in the height direction. can be obtained

In addition, the casing 10 of the part which forms the exit side connection flow path 18 may be produced by casting. Thereby, it is possible to easily form the exit-side connection flow passage 18 having a complicated shape.

As shown in FIG. 1, the on-off valve 60 which can control an opening degree is attached to the straight pipe 52 mentioned above.

The opening degree of the on-off valve 60 is controlled by, for example, a signal from a control unit (not shown) that controls the internal combustion engine in which the supercharger 1 is mounted. Thereby, the flow volume of the exhaust gas which flows through the bypass flow path 51 can be adjusted.

In addition, the attachment position of the on-off valve 60 becomes a thing which can be changed suitably, and you may attach it to the elbow storage 54, for example.

Moreover, the straight pipe 52 mentioned above may provide the expansion (contraction part) 62 which expands and contracts in an axial direction. The expansion 62 can absorb expansion and contraction of the straight pipe 52 in the axial direction. Thereby, the thermal expansion and thermal contraction which generate|occur|produce in the bypass pipe 50 can be absorbed.

When the on/off valve 60 is attached to the straight pipe 52, the expansion 62 is attached to the straight pipe 52 on the downstream side of the on/off valve 60 (the outlet side connection flow path 18 side). it is preferable Thereby, the on-off valve 60 can be attached to the casing 10 easily. In addition, the attachment position of the expansion 62 becomes a thing which can be changed suitably, and you may attach it to the straight pipe 52 on the upstream side of the on-off valve 60 .

Next, the flow of exhaust gas is demonstrated.

[When the on/off valve is closed]

In order to improve the performance of the turbocharger even when the internal combustion engine on which the turbocharger 1 is mounted is operating at a low load, for example, a nozzle (a nozzle smaller than a normal design) that achieves a high supercharge pressure even at a low load is selected There are cases. At such a low load, if a part of the exhaust gas is bypassed by the bypass pipe 50, the output of the turbine 30 decreases by the amount of the bypassed exhaust gas, and a desired boost pressure cannot be obtained. . For this reason, at the time of a low load, the on-off valve 60 is made into the closed state so that exhaust gas may not flow through the bypass flow path 51. As shown in FIG.

When the on-off valve 60 is in the closed state, all the exhaust gases flowing in from the gas inlet 12A drive the turbine 30 while flowing through the exhaust gas flow path 12a and the exhaust gas flow path 12b, so that the exhaust gas It flows through the flow path 12c and flows out from the gas outlet 12B (arrow Go in the figure).

[When the on/off valve is open]

In order to improve the performance of the turbocharger even when the internal combustion engine on which the turbocharger 1 is mounted is operating at a low load, for example, a nozzle (a nozzle smaller than a normal design) that achieves a high supercharge pressure even at a low load is selected There are cases. However, when such an internal combustion engine operates with a high load, the supercharge pressure of the supercharger 1 will become high too much. For this reason, at the time of a high load, in order to drop the output of the turbine 30 daringly, the on-off valve 60 is made into an open state so that exhaust gas may flow in the bypass flow path 51. As shown in FIG. The "open state" as used herein includes not only the state in which the degree of opening is 100% (the total open state) but also the state in which the degree of openness is larger than 0% and smaller than 100%.

When the on-off valve 60 is in the open state, a part of the exhaust gas flowing in from the gas inlet 12A drives the turbine 30 while flowing through the exhaust gas flow path 12a and the exhaust gas flow path 12b, It flows through the gas flow path 12c and flows out from the gas outlet 12B.

On the other hand, the other exhaust gas is guided from the exhaust gas flow path 12a to the straight flow path 53 (bypass flow path 51) via the inlet-side connection flow path 16 (arrow Bi in the drawing).

The exhaust gas guided to the straight flow path 53 is guided to the outlet side connection flow path 18 after it reaches the bent flow path 55 and is deflected.

The exhaust gas guided to the outlet side connection flow path 18 passes through the space S1 formed by the outer circumferential wall of the outer circumferential side ring 34c and the casing 10, and the exhaust gas flow path ( 12c) (arrow Bo in the figure).

Then, it joins with the exhaust gas which drove the turbine 30, and flows out from the gas outlet 12B (arrow Go in the figure).

In addition, when the on-off valve 60 is operated from the open state to the closed state, if the on-off valve 60 is operated abruptly, the flow rate of the exhaust gas flowing into the turbine 30 increases rapidly, and accordingly, the turbine The output of (30) increases rapidly. At the same time, the rotation speed of the impeller (not shown) of the compressor is rapidly increased. Then, there is a possibility that surging may occur in the compressor.

For this reason, in order to avoid surging in a compressor, it is preferable to close the on-off valve 60 gradually. For example, when operating the on-off valve 60 from the fully open state to the fully closed state, it is preferable to operate over 5 seconds or more.

In addition, it cannot be overemphasized that the operating time of the on-off valve 60 can be suitably changed according to the specification of each apparatus. However, it is preferable that the time for operating the on-off valve 60 from the open state to the closed state is longer than the time for operating the on-off valve 60 from the closed state to the open state.

In addition, even if the movable parts (turbine 30, rotor shaft 33, compressor (not shown), etc.) of the supercharger 1 are out of order, the internal combustion engine needs to be operated, so it is supplied to the exhaust gas flow path 12 Exhaust gas cannot be blocked. For this reason, in order to avoid further damage to the movable part, a mechanism for locking the movable part may be provided. In the case of this embodiment, since the bypass pipe 50 is provided in the turbine 30 side, it is preferable to consider the easiness of access by a worker, and to provide a lock mechanism to the compressor side.

In this embodiment, the following effects are exhibited.

Since the bending part formed in the bypass pipe 50 with which the casing 10 is equipped becomes only one point of the elbow storage 54, it is applicable to the small-sized supercharger 1 with a restriction|limiting in a layout. Moreover, compared with the case where there exist a bending part of two points, for example, the pressure loss which arises by a bending part can be suppressed. Moreover, since the bypass pipe 50 has a simple structure comprised by the two members (straight pipe 52 and the elbow pipe 54), the time and cost required for manufacture can be suppressed.

Moreover, the shape of the flow path is changing from the substantially circular shape matched with the elbow 54 to the flat shape of the outlet side connection flow path 18 maintaining the flow path area substantially constant. Thereby, for example, even when there is a restriction on the dimension in a predetermined direction due to the shape of the casing 10 on the gas outlet 12B side or relation with other parts, the flow path area can be reduced by making the shape thinner in the predetermined direction. can be obtained

Moreover, the opening/closing state of the on-off valve 60 provided in the bypass pipe 50 is controlled by the signal transmitted from the control part of the internal combustion engine in which the supercharger 1 is mounted, for example. Thereby, it is possible to control the flow rate of the exhaust gas flowing through the bypass flow passage 51 in accordance with the specifications and conditions of the internal combustion engine.

Moreover, the axial direction of the linear flow path 53 coincides with the inflow direction of the exhaust gas which flows in from the gas inlet 12A. Thereby, the exhaust gas flowing in from the gas inlet 12A is guided to the bypass flow passage 51 without being diverted. For this reason, the pressure loss of the exhaust gas guide|induced to the bypass piping can be suppressed.

Further, the straight pipe 52 is provided with an expansion 62 that expands and contracts in the axial direction. Thereby, the thermal expansion and thermal contraction which generate|occur|produce in the bypass pipe 50 by circulation of exhaust gas can be absorbed.

In addition, the shape of the bypass pipe 50 is not limited to the thing of the above-mentioned embodiment, You may change arbitrarily according to the specification of an internal combustion engine and a supercharger, and the layout of each apparatus which is not shown in figure.

Moreover, although the above-mentioned embodiment demonstrated using the axial flow turbine, it is applicable also to rotating machines, such as a power turbine.

1: Supercharger
10: casing
12 (12a, 12b, 12c): exhaust gas flow path
12A: gas inlet
12B: gas outlet
14: connection part
16: inlet side connection flow path
18: exit side connection flow path
30: turbine
31: turbine disk
32 : Dongik
33: rotor shaft
34 : nozzle ring
34a: guide vanes
34b: inner periphery side ring
34c: outer periphery side ring
50: bypass pipe
51: Bypass Euro
52: straight pipe
53: straight euro
54: Elbow
55: bend flow path
60: on-off valve
62: expansion

Claims (8)

A casing of a supercharger that forms an exhaust gas flow path through which exhaust gas discharged from an internal combustion engine flows, and a turbine driven by the exhaust gas flowing through the exhaust gas flow path is accommodated,
a bypass pipe for communicating the exhaust gas flow path at the exhaust gas inlet side and the exhaust gas flow path at the exhaust gas outlet side without interposing the turbine;
The bypass pipe is connected to the exhaust gas inlet side and is composed of a straight pipe having a straight flow path, and an elbow pipe connected to the straight pipe and the exhaust gas outlet side and having a bent flow path. of the casing. The method of claim 1,
The elbow has a substantially circular cross-section along the axis,
The casing of the supercharger, wherein the shape of the connection passage for communicating the connection portion with the elbow and the exhaust gas flow passage is changed from the substantially circular shape to a flat shape while maintaining a substantially constant flow passage area. 3. The method of claim 2,
The said connection flow path is the casing of the supercharger which is formed by casting. The method of claim 1,
The casing of the supercharger, wherein the bypass pipe is provided with an on-off valve in which opening and closing of the valve is controlled by a signal from the outside. The method of claim 1,
The casing of the supercharger, wherein the straight pipe is arranged such that an axial direction and an inflow direction of the exhaust gas flowing in from the exhaust gas inlet substantially coincide. 6. The method according to any one of claims 1 to 5,
The said straight pipe is provided with the expansion-contraction part which expands and contracts in an axial direction, The casing of a supercharger. A casing of a supercharger that forms an exhaust gas flow path through which exhaust gas discharged from an internal combustion engine flows, and a turbine driven by the exhaust gas flowing through the exhaust gas flow path is accommodated,
a bypass pipe for communicating the exhaust gas flow path at the exhaust gas inlet side and the exhaust gas flow path at the exhaust gas outlet side without interposing the turbine;
The bypass pipe has a substantially circular cross-sectional area along the axis,
The casing of the supercharger, wherein the connection flow path for communicating the connecting portion with the bypass pipe and the exhaust gas flow path has a flow path shape changing from the substantially circular shape to a flat shape while maintaining a substantially constant cross-sectional area. A casing of the supercharger according to claim 1 or 7;
and the turbine driven by the exhaust gas.

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