Patent Description:
A supercharger (e.g., turbocharger) may include a turbine for converting energy of exhaust gas discharged from an internal combustion engine (e.g., engine) into power (rotational force), and a compressor for compressing air supplied to the internal combustion engine by the power output from the turbine. The turbine of the supercharger includes a turbine wheel and a turbine housing accommodating the turbine wheel, and the compressor of the supercharger includes a compressor wheel mechanically coupled to the turbine wheel via a rotational shaft and a compressor housing accommodating the compressor wheel.

The housings (compressor housing, turbine housing) of the supercharger may be assembles obtained by fastening multiple components with fastening bolts (fastening members). The housing composed of multiple components has a risk that the fastening bolts are broken by wheel fragments flying when the wheel (compressor wheel, turbine wheel) is damaged and bursts during rotation, causing the wheel fragments to fly outside the housing. Therefore, the housing composed of multiple components is required to prevent wheel fragments from flying outside the housing, that is, to improve the containment.

<CIT> discloses a compressor housing that includes an outer compressor housing surrounding the outer periphery of a compressor wheel, and an inner compressor housing accommodated in the outer compressor housing and defining a scroll passage between the outer and inner compressor housings. The inner compressor housing disclosed in <CIT> includes a diffuser passage portion defining a diffuser passage for supplying air from the compressor wheel to the scroll passage between the diffuser passage portion and a bearing housing, a fastening portion fastened to the outer compressor housing by a fastening bolt, and an annular bellows portion disposed between the diffuser passage portion and the fastening portion.

Other examples of the prior art can be seen in documents <CIT>, <CIT>, <CIT> and <CIT>.

If the compressor wheel breaks during rotation of the compressor wheel, wheel fragments fly outward in the radial direction and enter the diffuser passage. At this time, the fastening bolt that fastens the outer compressor housing and the inner compressor housing is subjected to an impact load along the axial direction of the fastening bolt due to the wheel fragments such that the outer casing and the inner casing are spread apart. If the fastening bolt is broken by the impact load, the outer casing and the inner casing open, causing the wheel fragments to fly outside the housing.

The inner compressor housing disclosed in <CIT> is adapted to absorb an axial force by elastically and plastically deforming the annular bellows portion. By absorbing the axial force with the annular bellows portion, the load on the fastening portion is reduced, preventing the fastening bolt from breaking and the wheel fragments from flying outside the housing. However, the housing disclosed in <CIT> including the annular bellows portion is structurally complicated and may lead to an increase in cost.

In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide a turbine housing that has a simple structure and can effectively prevent wheel fragments from flying outside the turbine housing at the time of burst.

A turbine housing according to the present disclosure includes an inlet-side casing including a scroll portion having therein a scroll passage; an outlet-side casing fastened to the inlet-side casing by a first fastening member; and a passage forming member including a passage wall surface that defines an exhaust gas passage for guiding an exhaust gas from the scroll passage to a turbine wheel and fastened to the outlet-side casing by a second fastening member. The outlet-side casing includes: a cylindrical portion having therein an outlet passage through which the exhaust gas having being guided from the scroll passage to the turbine wheel and passed through the turbine wheel flows; a flange portion protruding radially outward from a downstream end portion of the cylindrical portion and configured to be fastened to the scroll portion by the first fastening member; and an annular plate portion protruding radially outward from an upstream end portion of the cylindrical portion and configured to be fastened to the passage forming member by the second fastening member. The annular plate portion has at least one recess that is recessed radially inward from an outer peripheral end of the annular plate portion. The annular plate portion abuts on a back surface of the passage forming member on an opposite side in an axial direction from the passage wall surface.

A supercharger according to the present disclosure includes a turbine wheel, and the turbine housing.

At least one embodiment of the present disclosure provides a turbine housing that has a simple structure and can effectively prevent wheel fragments from flying outside the turbine housing at the time of burst.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present disclosure.

The same features can be indicated by the same reference numerals and not described in detail.

<FIG> is a schematic cross-sectional view of a turbine side of a supercharger equipped with a turbine housing according to an embodiment of the present disclosure, in a cross-section including the axis of the turbine housing. <FIG> is a schematic configuration diagram for describing an overall configuration of the supercharger equipped with the turbine housing according to an embodiment of the present disclosure.

As shown in <FIG>, a turbine housing <NUM> according to some embodiments is mounted on a supercharger <NUM>.

As shown in <FIG> and <FIG>, the supercharger <NUM> (e.g., turbocharger) according to some embodiments includes at least a turbine wheel <NUM> and a turbine housing <NUM> accommodating the turbine wheel <NUM>. As shown in <FIG>, the supercharger <NUM> further includes a rotational shaft <NUM>, a bearing <NUM> rotatably supporting the rotational shaft <NUM>, a bearing housing <NUM> accommodating the bearing <NUM>, a compressor wheel <NUM>, and a compressor housing <NUM> accommodating the compressor wheel <NUM>.

Hereinafter, for example as shown in <FIG>, an extension direction of the axis LA of the turbine housing <NUM> will be referred to as an axial direction X, and a direction perpendicular to the axis LA will be referred to as a radial direction Y. Of the axial direction X, a side (the right side in the drawing) on which the turbine housing <NUM> is located with respect to the bearing housing <NUM> will be referred to as one side X1, and a side (the left side in the drawing) on which the compressor housing <NUM> is located with respect to the bearing housing <NUM> will be referred to as the other side X2.

As shown in <FIG>, the compressor housing <NUM> is disposed opposite to the turbine housing <NUM> across the bearing housing <NUM> in the axial direction X. Each of the turbine housing <NUM> and the compressor housing <NUM> is mechanically coupled to the bearing housing <NUM> by a fastening member such as a fastening bolt or a V clamp.

As shown in <FIG>, the rotational shaft <NUM> has a longitudinal direction along the axial direction X. The rotational shaft <NUM> is mechanically coupled to the turbine wheel <NUM> at one end portion <NUM> (an end portion on one side X1) in the longitudinal direction, and is mechanically coupled to the compressor wheel <NUM> at the other end portion <NUM> (an end portion on the other side X2) in the longitudinal direction. The turbine wheel <NUM> is disposed coaxially with the compressor wheel <NUM>.

As shown in <FIG>, the compressor wheel <NUM> is disposed on a supply line <NUM> for supplying air (combustion gas) to an engine <NUM> (combustion device). The turbine wheel <NUM> is disposed on a discharge line <NUM> for discharging the exhaust gas from the engine <NUM>.

The supercharger <NUM> rotates the turbine wheel <NUM> by the exhaust gas introduced from the engine <NUM> into the turbine housing <NUM> through the discharge line <NUM>. Since the compressor wheel <NUM> is mechanically coupled to the turbine wheel <NUM> via the rotational shaft <NUM>, the compressor wheel <NUM> rotates in conjunction with the rotation of the turbine wheel <NUM>. Rotating the compressor wheel <NUM>, the supercharger <NUM> compresses the air (combustion gas) introduced into the compressor housing <NUM> through the supply line <NUM> and sends the compressed air to the engine <NUM>.

In the illustrated embodiment, as shown in <FIG>, the compressor housing <NUM> has an air intake port <NUM> for introducing air from the outside of the compressor housing <NUM> along the axial direction X, and an air supply port <NUM> for discharging the air having passed through the compressor wheel <NUM> to the outside of the compressor housing <NUM> along the radial direction Y and sending the discharged air to the engine <NUM>.

In the illustrated embodiment, as shown in <FIG>, the turbine housing <NUM> has an exhaust gas introduction port <NUM> for introducing the exhaust gas into the turbine housing <NUM> from the outer side in the radial direction Y, and an exhaust gas discharge port <NUM> for discharging the exhaust gas having rotated the turbine wheel <NUM> to the outside of the turbine housing <NUM> along the axial direction X.

<FIG> is a partial enlarged cross-sectional view of the main portion shown in <FIG>.

As shown in <FIG> and <FIG>, the turbine housing <NUM> has a scroll passage <NUM> through which the exhaust gas before passing through the turbine wheel <NUM> flows, an exhaust gas passage <NUM> disposed between the scroll passage <NUM> and the turbine wheel <NUM> for guiding the exhaust gas from the scroll passage <NUM> to the turbine wheel <NUM>, and an outlet passage <NUM> through which the exhaust gas having being guided from the scroll passage <NUM> to the turbine wheel <NUM> and passed through the turbine wheel <NUM> flows.

The exhaust gas discharged from the engine <NUM> passes through the exhaust gas introduction port <NUM>, the scroll passage <NUM>, and the exhaust gas passage <NUM> of the turbine housing <NUM> in this order, and is then sent to the turbine wheel <NUM>. The exhaust gas sent to the turbine wheel <NUM> flows through the outlet passage <NUM> to one side X1 along the axial direction X, and is then discharged from the exhaust gas discharge port <NUM> to the outside of the turbine housing <NUM>.

As shown in <FIG> and <FIG>, the turbine housing <NUM> includes an inlet-side casing <NUM>, an outlet-side casing <NUM> fastened to the inlet-side casing <NUM> by a first fastening member <NUM>, and a passage forming member <NUM> fastened to the outlet-side casing <NUM> by a second fastening member <NUM>.

As shown in <FIG> and <FIG>, the inlet-side casing <NUM> includes a scroll portion <NUM> having therein the scroll passage <NUM>. The scroll passage <NUM> is defined by an inner wall surface <NUM> of the scroll portion <NUM>. Further, the inlet-side casing <NUM> has the exhaust gas introduction port <NUM>.

The scroll passage <NUM> is a passage for guiding the exhaust gas introduced into the turbine housing <NUM> through the exhaust gas introduction port <NUM> to the turbine wheel <NUM>. The scroll passage <NUM> has a scroll shape surrounding the periphery (the outer side in the radial direction Y) of the turbine wheel <NUM>. The scroll passage <NUM> communicates with the exhaust gas introduction port <NUM> disposed upstream in the exhaust gas flow direction.

As shown in <FIG>, the passage forming member <NUM> includes a passage wall surface <NUM> defining the exhaust gas passage <NUM>. The passage wall surface <NUM> extends along a direction intersecting (perpendicular to) the axis LA.

In the illustrated embodiment, the passage forming member <NUM> is formed separately from the inlet-side casing <NUM>. The passage forming member <NUM> includes an annular plate portion <NUM>. The plate portion <NUM> includes a fastened portion <NUM> to which the second fastening member <NUM> is fastened, and the above-described passage wall surface <NUM> formed on the other side X2. In the illustrated embodiment, the plate portion <NUM> is formed in an annular shape, but in other embodiments, the plate portion <NUM> may be formed in an arc shape extending along the circumferential direction about the axis LA.

In the illustrated embodiment, the inlet-side casing <NUM> further includes an exhaust gas passage portion <NUM> extending radially inward from an inner end portion <NUM> (other-side inner end portion) of the scroll portion <NUM> on the other side X2. The exhaust gas passage portion <NUM> includes a bearing-side passage wall surface <NUM> defining the exhaust gas passage <NUM> between the bearing-side passage wall surface <NUM> and the passage wall surface <NUM>. The bearing-side passage wall surface <NUM> extends along a direction intersecting (perpendicular to) the axis LA on the other side X2 of the passage wall surface <NUM> and faces the passage wall surface <NUM> located on one side X1.

The exhaust gas passage <NUM> is a passage for guiding the exhaust gas from the scroll passage <NUM> to the turbine wheel <NUM>. The exhaust gas passage <NUM> is disposed between the scroll passage <NUM> and the turbine wheel <NUM> and extends along a direction intersecting (perpendicular to) the axis LA. The exhaust gas passage <NUM> communicates with the scroll passage <NUM> disposed upstream in the exhaust gas flow direction.

As shown in <FIG> and <FIG>, the outlet-side casing <NUM> includes a cylindrical portion <NUM> having therein the outlet passage <NUM>, a flange portion <NUM> protruding radially outward from a downstream end portion <NUM> of the cylindrical portion <NUM>, and an annular plate portion <NUM> protruding radially outward from an upstream end portion <NUM> of the cylindrical portion <NUM>.

As shown in <FIG> and <FIG>, the cylindrical portion <NUM> has an inner wall surface <NUM> extending along the axis LA and defining the outlet passage <NUM>. The downstream end portion <NUM> of the cylindrical portion <NUM> is located downstream (one side X1) of the upstream end portion <NUM> in the exhaust gas flow direction and has the exhaust gas discharge port <NUM>.

The outlet passage <NUM> is a passage for guiding the exhaust gas having passed through the turbine wheel <NUM> to the exhaust gas discharge port <NUM>. The outlet passage <NUM> is disposed on one side X1 of the turbine wheel <NUM>, extends along the axial direction X, and communicates with each of the exhaust gas passage <NUM> located upstream in the exhaust gas flow direction and the exhaust gas discharge port <NUM> located downstream in the exhaust gas flow direction.

As shown in <FIG>, the flange portion <NUM> is configured to be fastened to the scroll portion <NUM> of the inlet-side casing <NUM> by the first fastening member <NUM>.

In the embodiment shown in <FIG>, the scroll portion <NUM> includes a protruding portion <NUM> protruding to one side X1 from the end portion on one side X1, and an end surface <NUM> of the protruding portion <NUM> abuts on an outer peripheral edge surface <NUM> formed on the outer peripheral edge of the flange portion <NUM> on the other side X2. The outer peripheral edge surface <NUM> of the flange portion <NUM> is located on one side X1 with respect to the inner peripheral edge surface <NUM>. The first fastening member <NUM> has a fastening portion <NUM> having a male-threaded outer periphery. The first fastening member <NUM> connects and fixes the scroll portion <NUM> of the inlet-side casing <NUM> and the flange portion <NUM> of the outlet-side casing <NUM> by inserting the fastening portion <NUM> into a flange-side insertion hole <NUM> formed in the flange portion <NUM>, and screwing (fastening) it into a fastened portion <NUM> of the protruding portion <NUM> having a female-threaded inner periphery.

As shown in <FIG>, the annular plate portion <NUM> is configured to be fastened to the passage forming member <NUM> by the second fastening member <NUM>.

In the embodiment shown in <FIG>, a surface <NUM> of the annular plate portion <NUM> on the other side X2 abuts on a back surface <NUM> of the plate portion <NUM> on the opposite side (the other side X2) in the axial direction X from the passage wall surface <NUM>. The back surface <NUM> has the fastened portion <NUM>. The second fastening member <NUM> has a fastening portion <NUM> having a male-threaded outer periphery. The second fastening member <NUM> connects and fixes the passage forming member <NUM> and the annular plate portion <NUM> of the outlet-side casing <NUM> by inserting the fastening portion <NUM> into an insertion hole <NUM> formed in the annular plate portion <NUM>, and screwing (fastening) it into the fastened portion <NUM> of the passage forming member <NUM> having a female-threaded inner periphery. The insertion hole <NUM> is formed at a position inward of the flange-side insertion hole <NUM> and the fastened portion <NUM> of the protruding portion <NUM> in the radial direction Y.

In the illustrated embodiment, as shown in <FIG>, the bearing housing <NUM> includes a cylindrical portion <NUM> extending along the axial direction X, and a flange portion <NUM> protruding outward in the radial direction Y from the outer periphery of an end portion of the cylindrical portion <NUM> on one side X1. The inlet-side casing <NUM> has a back surface <NUM> on the opposite side (the other side X2) in the axial direction X from the bearing-side passage wall surface <NUM> of the exhaust gas passage portion <NUM>, and the back surface <NUM> abuts on a surface <NUM> of the flange portion <NUM> of the bearing housing <NUM> on one side X1. In the illustrated embodiment, the inlet-side casing <NUM> is connected and fixed to the bearing housing <NUM> by securing the back surface <NUM> to the surface <NUM> with a fastening member (not shown).

In the illustrated embodiment, the turbine wheel <NUM> is accommodated in a space defined by the inner wall surface <NUM> of the cylindrical portion <NUM> and an end surface <NUM> of the bearing housing <NUM>.

<FIG> is a diagram showing an example of the annular plate portion of the turbine housing according to an embodiment of the present disclosure. <FIG> is a diagram showing another example of the annular plate portion of the turbine housing according to an embodiment of the present disclosure.

As shown in <FIG>, the turbine housing <NUM> according to some embodiments includes the above-described inlet-side casing <NUM>, the above-described outlet-side casing <NUM>, and the above-described passage forming member <NUM>. The outlet-side casing <NUM> includes the above-described cylindrical portion <NUM>, the above-described flange portion <NUM>, and the above-described annular plate portion <NUM>. As shown in <FIG> and <FIG>, the annular plate portion <NUM> has at least one recess <NUM> that is recessed inward in the radial direction Y from an outer peripheral end <NUM>.

In the illustrated embodiments, as shown in <FIG> and <FIG>, the recess <NUM> (9A, 9B) includes a pair of side wall portions <NUM> and <NUM> extending along a direction intersecting (perpendicular to) the circumferential direction, and a bottom wall portion <NUM> connecting the radially inner ends of the pair of side wall portions <NUM> and <NUM>.

In the embodiment shown in <FIG>, the annular plate portion <NUM> has one recess <NUM> (9A). In the embodiment shown in <FIG>, the annular plate portion <NUM> has a plurality of recesses <NUM> (9B).

When the turbine wheel <NUM> breaks during rotation of the turbine wheel <NUM>, wheel fragments fly outward in the radial direction Y and enter the exhaust gas passage <NUM>, so that the wheel fragments may apply the impact load F (axial load, see <FIG>) to the turbine housing <NUM> such that the inlet-side casing <NUM> and the outlet-side casing <NUM> are spread apart. If the annular plate portion <NUM> of the outlet-side casing <NUM> is of disk shape having no recess <NUM>, the impact load F transmitted from the passage forming member <NUM> to the annular plate portion <NUM> can be transmitted over the entire circumference along the circumferential direction, and the impact load F can be distributed over the entire circumference. The annular plate portion <NUM> of disk shape having no recess <NUM> is so rigid that the first fastening member <NUM>, which fastens the inlet-side casing <NUM> to the outlet-side casing <NUM>, is broken by the impact load F before the annular plate portion <NUM> is deformed by the impact load F.

With the above configuration, the annular plate portion <NUM> of the outlet-side casing <NUM> has at least one recess <NUM> that is recessed radially inward from the outer peripheral end <NUM>. That is, the turbine housing <NUM> has a simple structure in which the annular plate portion <NUM> of the outlet-side casing <NUM> has at least one recess <NUM>. The annular plate portion <NUM> having at least one recess <NUM> can effectively reduce the rigidity compared to the case where the annular plate portion <NUM> is of disk shape having no recess <NUM>, because the recess <NUM> prevents the transmission of the impact load F along the circumferential direction while the recess <NUM> creates a stress concentration zone which becomes the starting point of deformation.

When the rigidity of the annular plate portion <NUM> is reduced, the amount of deformation of the annular plate portion <NUM> upon receiving the impact load F increases, and the amount of impact energy that can be absorbed when the annular plate portion <NUM> deforms under the impact load F increases. By deforming the annular plate portion <NUM> with reduced rigidity to absorb impact energy before the first fastening member <NUM>, which fastens the inlet-side casing <NUM> and the outlet-side casing <NUM>, is broken by the impact load F, the turbine housing <NUM> can reduce the impact load F applied to the first fastening member <NUM> and prevent the first fastening member <NUM> from breaking. Further, by preventing the first fastening member <NUM> from breaking, the turbine housing <NUM> can effectively prevent the wheel fragments from flying outside the turbine housing <NUM> at the time of burst.

In some embodiments, as shown in <FIG> and <FIG>, the annular plate portion <NUM> has at least one insertion hole <NUM>, as described above, formed at a circumferential position different from the circumferential position corresponding to the at least one recess <NUM> to allow the second fastening member <NUM> to pass through. The at least one recess <NUM> is configured such that a deepest portion <NUM> of the recess <NUM> in the radial direction (radially innermost portion) is located inward of the at least one insertion hole <NUM> in the radial direction Y.

In the illustrated embodiments, as shown in <FIG> and <FIG>, the deepest portion <NUM> is provided at the bottom wall portion <NUM>. In the embodiments shown in <FIG> and <FIG>, the bottom wall portion <NUM> is at the same position in the radial direction Y as the outer wall surface <NUM> of the cylindrical portion <NUM>.

With the above configuration, the annular plate portion <NUM> is fastened to the passage forming member <NUM> by inserting the second fastening member <NUM> into the insertion hole <NUM> formed at a circumferential position different from the circumferential position corresponding to the recess <NUM>. In the annular plate portion <NUM>, since the deepest portion <NUM> of the recess <NUM> in the radial direction (radially innermost portion) is located radially inward of the insertion hole <NUM>, the recess <NUM> prevents the impact load F transmitted from the passage forming member <NUM> through the insertion hole <NUM> from being transmitted along the circumferential direction. By preventing the transmission of the impact load F along the circumferential direction to narrow the range where the impact load F is borne, the annular plate portion <NUM> can reduce the rigidity in this range and more effectively absorb the impact energy in this range.

In some embodiments, as shown in <FIG>, the at least one insertion hole <NUM> includes a plurality of insertion holes <NUM>, and the at least one recess <NUM> includes a plurality of recesses <NUM>. Each of the plurality of recesses <NUM> is disposed between two adjacent insertion holes <NUM> of the plurality of insertion holes <NUM> in the circumferential direction.

With the above configuration, since each of the plurality of recesses <NUM> is disposed between two adjacent insertion holes <NUM> of the plurality of insertion holes <NUM> in the circumferential direction, the recess <NUM> prevents the impact load F transmitted from the passage forming member <NUM> through one insertion hole <NUM> from being transmitted along the circumferential direction to a portion with the other insertion hole <NUM>. By preventing the transmission of the impact load F along the circumferential direction to the portion with the other insertion hole <NUM> to make each portion with the insertion hole <NUM> bear the impact load F, the annular plate portion <NUM> can reduce the rigidity in each portion with the insertion hole <NUM> and more effectively absorb the impact energy in each portion.

In some embodiments, as shown in <FIG>, the annular plate portion <NUM> has a plurality of protrusions <NUM> each of which is defined by two adjacent recesses <NUM> of the plurality of recesses <NUM> in the circumferential direction. Each of the plurality of protrusions <NUM> is provided with one of the plurality of insertion holes <NUM>.

In the illustrated embodiment, each of the plurality of protrusions <NUM> includes a pair of side wall portions <NUM>, <NUM> which sandwich the insertion hole <NUM> provided in the protrusion <NUM>, and an outer wall portion (outer peripheral end <NUM>) connecting the radially outer ends of the pair of side wall portions <NUM>, <NUM>. The insertion hole <NUM> is preferably formed in the center of the protrusion <NUM> in the circumferential direction.

With the above configuration, since each protrusion <NUM> provided with one of the plurality of insertion holes <NUM> has a small angular range θ in the circumferential direction, the annular plate portion <NUM> limits the transmission along the circumferential direction of the impact load F transmitted from the passage forming member <NUM> through the insertion hole <NUM> to the angular range θ of the protrusion <NUM>. By preventing the transmission of the impact load F along the circumferential direction to limit the range where the impact load F is borne to the angular range θ, the annular plate portion <NUM> can reduce the rigidity in the angular range θ and more effectively absorb the impact energy in the angular range θ.

In some embodiments, as shown in <FIG>, the flange portion <NUM> includes at least one flange-side insertion hole <NUM>, as described above, into which the first fastening member <NUM> is inserted. The at least one insertion hole <NUM> is configured to have a smaller hole diameter than the at least one flange-side insertion hole <NUM>. That is, the hole diameter D1 of the insertion hole <NUM> is smaller than the hole diameter D2 of the flange-side insertion hole <NUM>.

With the above configuration, since the insertion hole <NUM>, into which the second fastening member <NUM> is inserted, has a smaller hole diameter than the flange-side insertion hole <NUM>, into which the first fastening member <NUM> is inserted, the impact load F input from the second fastening member <NUM> to the insertion hole <NUM> can be increased. More specifically, when the passage forming member <NUM> or the inlet-side casing <NUM> slips with respect to the outlet-side casing <NUM> upon collision of wheel fragments with the turbine housing <NUM>, the second fastening member <NUM> and the insertion hole <NUM>, where the gap between members is small, can be brought into closer contact earlier than the first fastening member <NUM> and the flange-side insertion hole <NUM>, where the gap between members is large, so that the impact load F input from the second fastening member <NUM> to the insertion hole <NUM> can be increased. By increasing the impact load F input from the second fastening member <NUM> to the insertion hole <NUM>, the turbine housing <NUM> can mitigate the impact load F input from the first fastening member <NUM> to the flange-side insertion hole <NUM> and thus prevent the first fastening member <NUM> from breaking more effectively.

As described above, in some embodiments, for example as shown in <FIG>, the passage forming member <NUM> is formed separately from the inlet-side casing <NUM>.

If the passage forming member <NUM> and the inlet-side casing <NUM> are integrally formed, the annular plate portion <NUM> fastened to the passage forming member <NUM> (inlet-side casing <NUM>) via the second fastening member <NUM> is supported by the inlet-side casing <NUM>, which suppresses the deformation due to the impact load F. With the above configuration, since the passage forming member <NUM> is formed separately from the inlet-side casing <NUM>, the annular plate portion <NUM> can easily deform without limitation when the inlet-side casing <NUM> is subjected to the impact load F, so that the first fastening member <NUM> can be prevented from breaking more effectively.

In some embodiments, as shown in <FIG> and <FIG>, the passage forming member <NUM> includes the plate portion <NUM> including the fastened portion <NUM> to which the second fastening member <NUM> is fastened and the passage wall surface <NUM>, and at least one fixation nozzle <NUM> protruding from the passage wall surface <NUM> of the plate portion <NUM>.

In the illustrated embodiment, as shown in <FIG>, the at least one fixation nozzle <NUM> includes a plurality of fixation nozzles <NUM> arranged at intervals along the circumferential direction. Each of the plurality of fixation nozzles <NUM> extends along a direction intersecting the radial direction Y. The fixation nozzle <NUM> may be configured such that the circumferential positions of leading and trailing edges are different from each other.

With the above configuration, the passage forming member <NUM> includes the plate portion <NUM> including the fastened portion <NUM> to which the second fastening member <NUM> is fastened and the passage wall surface <NUM>, and at least one fixation nozzle <NUM> protruding from the passage wall surface <NUM>. Even in such a case, by deforming the annular plate portion <NUM> by the impact load F transmitted from the plate portion <NUM> of the passage forming member <NUM> to the annular plate portion <NUM> of the outlet-side casing <NUM>, the first fastening member <NUM> can be prevented from breaking.

<FIG> is a schematic cross-sectional view of the supercharger equipped with the turbine housing according to another embodiment of the present disclosure, in a cross-section including the axis.

In some embodiments, as shown in <FIG>, the passage forming member <NUM> is formed integrally with the inlet-side casing <NUM>. In the illustrated embodiment, an outer peripheral end <NUM> of the passage forming member <NUM> is integrally formed with an inner end portion <NUM> (one-side inner end portion) of the scroll portion <NUM> on one side X1.

With the above configuration, since the passage forming member <NUM> is formed integrally with the inlet-side casing <NUM>, when the impact load F that spreads the inlet-side casing <NUM> and the outlet-side casing <NUM> is applied to the passage forming member <NUM>, part of the impact load F can be transmitted to the inlet-side casing <NUM> (inner end portion <NUM>). When the passage forming member <NUM> transmits part of the impact load F to the inlet-side casing <NUM> (inner end portion <NUM>), the impact load F transmitted from the passage forming member <NUM> to the outlet-side casing <NUM> can be migrated, and the first fastening member <NUM> can be prevented from breaking more effectively.

The supercharger <NUM> according to some embodiments includes the above-described turbine wheel <NUM>, and the above-described turbine housing <NUM>. With the above configuration, since the turbine housing <NUM> prevents the first fastening member <NUM> from breaking, the supercharger <NUM> can effectively prevent wheel fragments from flying outside the turbine housing <NUM> at the time of burst.

The contents described in the above embodiments would be understood as follows, for instance.

When the turbine wheel breaks during rotation of the turbine wheel, wheel fragments fly outward in the radial direction and enter the exhaust gas passage, so that the wheel fragments may apply the impact load to the turbine housing such that the inlet-side casing and the outlet-side casing are spread apart. If the annular plate portion is of disk shape having no recess, the impact load transmitted from the passage forming member to the annular plate portion can be transmitted over the entire circumference along the circumferential direction, and the impact load can be distributed over the entire circumference. The annular plate portion of disk shape having no recess is so rigid that the first fastening member, which fastens the inlet-side casing and the outlet-side casing, is broken by the impact load before the annular plate portion is deformed by the impact load.

With the above configuration (<NUM>), the annular plate portion of the outlet-side casing has at least one recess that is recessed radially inward from the outer peripheral end. That is, the turbine housing has a simple structure in which the annular plate portion of the outlet-side casing has at least one recess. The annular plate portion having at least one recess can effectively reduce the rigidity compared to the case where the annular plate portion is of disk shape having no recess, because the recess prevents the transmission of the impact load along the circumferential direction while the recess creates a stress concentration zone which becomes the starting point of deformation.

When the rigidity of the annular plate portion is reduced, the amount of deformation of the annular plate portion upon receiving the impact load increases, and the amount of impact energy that can be absorbed when the annular plate portion deforms under the impact load increases. By deforming the annular plate portion with reduced rigidity to absorb impact energy before the first fastening member, which fastens the inlet-side casing and the outlet-side casing, is broken by the impact load, the turbine housing can reduce the impact load applied to the first fastening member and prevent the first fastening member from breaking. Further, by preventing the first fastening member from breaking, the turbine housing can effectively prevent the wheel fragments from flying outside the turbine housing at the time of burst.

(<NUM>) In some embodiments, in the turbine housing described in the above (<NUM>), the annular plate portion has at least one insertion hole formed at a circumferential position different from a circumferential position corresponding to the at least one recess to allow the second fastening member to pass through. The at least one recess is configured such that a deepest portion of the at least one recess in the radial direction is located radially inward of the at least one insertion hole.

With the above configuration (<NUM>), the annular plate portion is fastened to the passage forming member by inserting the second fastening member into the insertion hole formed at a circumferential position different from the circumferential position corresponding to the recess. In the annular plate portion, since the deepest portion of the recess in the radial direction (radially innermost portion) is located radially inward of the insertion hole, the recess prevents the impact load transmitted from the passage forming member through the insertion hole from being transmitted along the circumferential direction. By preventing the transmission of the impact load along the circumferential direction to narrow the range where the impact load is borne, the annular plate portion can reduce the rigidity in this range and more effectively absorb the impact energy in this range.

(<NUM>) In some embodiments, in the turbine housing described in the above (<NUM>), the at least one insertion hole includes a plurality of insertion holes. The at least one recess includes a plurality of recesses. Each of the plurality of recesses is disposed between two adjacent insertion holes of the plurality of insertion holes in a circumferential direction.

With the above configuration (<NUM>), since each of the plurality of recesses is disposed between two adjacent insertion holes of the plurality of insertion holes in the circumferential direction, the recess prevents the impact load transmitted from the passage forming member through one insertion hole from being transmitted along the circumferential direction to a portion with the other insertion hole. By preventing the transmission of the impact load along the circumferential direction to the portion with the other insertion hole to make each portion with the insertion hole bear the impact load, the annular plate portion can reduce the rigidity in each portion with the insertion hole and more effectively absorb the impact energy in each portion.

(<NUM>) In some embodiments, in the turbine housing described in the above (<NUM>), the annular plate portion has a plurality of protrusions each of which is defined by two adjacent recesses of the plurality of recesses in the circumferential direction. Each of the plurality of protrusions is provided with one of the plurality of insertion holes.

With the above configuration (<NUM>), since each protrusion provided with one of the plurality of insertion holes has a small angular range in the circumferential direction, the annular plate portion limits the transmission along the circumferential direction of the impact load transmitted from the passage forming member through the insertion hole to the angular range of the protrusion. By preventing the transmission of the impact load along the circumferential direction to limit the range where the impact load is borne to the angular range, the annular plate portion can reduce the rigidity in the angular range and more effectively absorb the impact energy in the angular range.

(<NUM>) In some embodiments, in the turbine housing described in any one of the above (<NUM>) to (<NUM>), the flange portion has at least one flange-side insertion hole into which the first fastening member is inserted. The at least one insertion hole is configured to have a smaller hole diameter than the at least one flange-side insertion hole.

With the above configuration (<NUM>), since the insertion hole, into which the second fastening member is inserted, has a smaller hole diameter than the flange-side insertion hole, into which the first fastening member is inserted, the impact load input from the second fastening member to the insertion hole can be increased. More specifically, when the passage forming member or the inlet-side casing slips with respect to the outlet-side casing upon collision of wheel fragments with the turbine housing, the second fastening member and the insertion hole, where the gap between members is small, can be brought into closer contact earlier than the first fastening member and the flange-side insertion hole, where the gap between members is large, so that the impact load input from the second fastening member to the insertion hole can be increased. By increasing the impact load input from the second fastening member to the insertion hole, the turbine housing can mitigate the impact load input from the first fastening member to the flange-side insertion hole and thus prevent the first fastening member from breaking more effectively.

(<NUM>) In some embodiments, in the turbine housing described in any one of the above (<NUM>) to (<NUM>), the passage forming member is formed integrally with the inlet-side casing.

With the above configuration (<NUM>), since the passage forming member is formed integrally with the inlet-side casing, when the impact load that spreads the inlet-side casing and the outlet-side casing is applied to the passage forming member, part of the impact load can be transmitted to the inlet-side casing. When the passage forming member transmits part of the impact load to the inlet-side casing, the impact load transmitted from the passage forming member to the outlet-side casing can be migrated, and the first fastening member can be prevented from breaking more effectively.

(<NUM>) In some embodiments, in the turbine housing described in any one of the above (<NUM>) to (<NUM>), the passage forming member is formed separately from the inlet-side casing.

If the passage forming member and the inlet-side casing are integrally formed, the annular plate portion fastened to the passage forming member (inlet-side casing) via the second fastening member is supported by the inlet-side casing, which suppresses the deformation due to the impact load. With the above configuration (<NUM>), since the passage forming member is formed separately from the inlet-side casing, the annular plate portion can easily deform without limitation when the inlet-side casing is subjected to the impact load, so that the first fastening member can be prevented from breaking more effectively.

(<NUM>) In some embodiments, in the turbine housing described in the above (<NUM>), the passage forming member includes: a plate portion including a fastened portion to which the second fastening member is fastened and the passage wall surface; and at least one fixation nozzle protruding from the passage wall surface of the plate portion.

With the above configuration (<NUM>), the passage forming member includes the plate portion including the fastened portion to which the second fastening member is fastened and the passage wall surface, and at least one fixation nozzle protruding from the passage wall surface. In this case, by deforming the annular plate portion by the impact load transmitted from the plate portion of the passage forming member to the annular plate portion of the outlet-side casing, the first fastening member can be prevented from breaking.

(<NUM>) A supercharger according to at least one embodiment of the present disclosure includes a turbine wheel and the turbine housing described in any one of the above (<NUM>) to (<NUM>).

Claim 1:
A turbine housing (<NUM>), comprising:
an inlet-side casing (<NUM>) including a scroll portion (<NUM>) having therein a scroll passage (<NUM>);
an outlet-side casing (<NUM>) fastened to the inlet-side casing (<NUM>) by a first fastening member(<NUM>); and
a passage forming member (<NUM>) including a passage wall surface (<NUM>) that defines an exhaust gas passage (<NUM>) for guiding an exhaust gas from the scroll passage (<NUM>) to a turbine wheel (<NUM>),
wherein the outlet-side casing (<NUM>) includes:
a cylindrical portion (<NUM>) having therein an outlet passage (<NUM>) through which the exhaust gas having being guided from the scroll passage (<NUM>) to the turbine wheel (<NUM>) and passed through the turbine wheel (<NUM>) flows;
a flange portion (<NUM>) protruding radially outward from a downstream end portion of the cylindrical portion (<NUM>)
wherein the flange portion (<NUM>) is fastened to the scroll portion (<NUM>) by the first fastening member (<NUM>), and
characterized in that
the passage forming member (<NUM>) is fastened to the outlet-side casing (<NUM>) by a second fastening member (<NUM>);
wherein the outlet-side casing (<NUM>) further includes an annular plate portion (<NUM>) protruding radially outward from an upstream end portion of the cylindrical portion (<NUM>) and fastened to the passage forming member (<NUM>) by the second fastening member (<NUM>), wherein the annular plate portion (<NUM>) abuts on a back surface (<NUM>) of the passage forming member (<NUM>) on an opposite side in an axial direction from the passage wall surface (<NUM>);
wherein the annular plate portion (<NUM>) has at least one recess (<NUM>) that is recessed radially inward from an outer peripheral end of the annular plate portion (<NUM>).