supercharger

Abstract

The supercharger includes: a variable nozzle unit, which is arranged between the turbine housing and the bearing housing; and a disc spring, which is arranged between the variable nozzle unit and the bearing housing and applies force in a direction to expand the space between the variable nozzle unit and the bearing housing in the axial direction. The disc spring contacts the variable nozzle unit at a first contact point on the outer peripheral side and contacts the bearing housing at a second contact point on the inner peripheral side. In the axial direction, the first contact point is located closer to the bearing housing than the second contact point.

Description

Technical Field

[0001] The present disclosure relates to superchargers. Background Art

[0002] In the past, there is a known supercharger described in the following patent document 1. The supercharger has a variable nozzle unit for adjusting the opening of the nozzle flow path of the turbine. If such a variable nozzle unit is completely fixed to the housing (for example, fixed by a fastening component), it is possible that the operation of the variable nozzle unit will be negatively affected during thermal expansion. Therefore, the variable nozzle unit is appropriately pressed relative to the turbine housing to a degree that allows thermal deformation and is fixed in position. Therefore, a disc spring is provided between the variable nozzle unit and the bearing housing. Moreover, the variable nozzle unit is pressed against the turbine housing by the force of the disc spring, thereby being positioned.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-68153

[0004] During the operation of this supercharger, the disc spring's contact with the variable nozzle unit reaches a high temperature. In contrast, the bearing housing's other side, cooled by water or oil cooling, maintains a relatively low temperature. This temperature difference creates a temperature distribution in the disc spring during supercharger operation, with higher temperatures on the outer circumference and lower temperatures on the inner circumference. Furthermore, this temperature distribution causes the disc spring to thermally deform in a direction that reduces the spring load, potentially reducing the load pressing the variable nozzle unit against the turbine housing. If this pressing load is too low, abnormal noise, wear, contact between the variable nozzle unit and the impeller, performance fluctuations, and control deviations of the variable nozzle unit may occur. Summary of the Invention

[0005] Therefore, the present disclosure describes a supercharger that suppresses a decrease in the spring load of a spring member that urges a variable nozzle unit at high temperatures.

[0006] A supercharger according to one embodiment of the present disclosure includes: a variable nozzle unit disposed between a turbine housing and a bearing housing; and an annular spring member disposed between the variable nozzle unit and the bearing housing for applying a force in a direction that expands the space between the variable nozzle unit and the bearing housing in the direction of the rotation axis. The spring member contacts the variable nozzle unit at a first contact point on the outer circumference and contacts the bearing housing at a second contact point on the inner circumference. In the direction of the rotation axis, the first contact point is located closer to the bearing housing than the second contact point.

[0007] According to the supercharger of the present disclosure, it is possible to suppress a decrease in the spring load of the spring member that urges the variable nozzle unit at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional view showing a supercharger according to the embodiment.

[0009] Figure 2 It is a cross-sectional view showing an enlarged view of the variable nozzle unit and the vicinity of the supercharger.

[0010] Figure 3 This is a cross-sectional view showing a disc spring of a supercharger.

[0011] Figure 4 (a) means Figure 3 (b) is a cross-sectional view showing a deformed disc spring, and (c) is a cross-sectional view showing a deformed disc spring of a conventional disc spring for comparison. DETAILED DESCRIPTION

[0012] A supercharger according to one embodiment of the present disclosure includes: a variable nozzle unit disposed between a turbine housing and a bearing housing; and an annular spring member disposed between the variable nozzle unit and the bearing housing for applying a force in a direction that expands the space between the variable nozzle unit and the bearing housing in the direction of the rotation axis. The spring member contacts the variable nozzle unit at a first contact point on the outer circumference and contacts the bearing housing at a second contact point on the inner circumference. In the direction of the rotation axis, the first contact point is located closer to the bearing housing than the second contact point.

[0013] The spring member may be a disc spring disposed along the conical surface of an imaginary cone having the rotation axis as the conical axis. Furthermore, the supercharger of the present disclosure may further include a heat shield plate, which is sandwiched between the variable nozzle unit and the spring member in the direction of the rotation axis and shields the spring member from heat from the turbine, with the first contact point of the spring member in contact with the heat shield plate.

[0014] Alternatively, the variable nozzle unit may include two nozzle rings arranged along the rotation axis, wherein the nozzle ring located on the bearing housing side is pressed against a predetermined portion of the turbine housing along the rotation axis by the urging force of a spring member.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Figure 1 This is a cross-sectional view of the variable geometry supercharger 1 taken along a section including the rotation axis H. The supercharger 1 is suitable for use in internal combustion engines of ships and vehicles, for example.

[0016] like Figure 1 As shown, the supercharger 1 includes a turbine 2 and a compressor 3. The turbine 2 includes a turbine housing 4 and a turbine wheel 6 housed in the turbine housing 4. The turbine housing 4 has a scroll flow path 16 extending circumferentially around the turbine wheel 6. The compressor 3 includes a compressor housing 5 and a compressor wheel 7 housed in the compressor housing 5. The compressor housing 5 has a scroll flow path 17 extending circumferentially around the compressor wheel 7.

[0017] The turbine impeller 6 is provided at one end of a 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 bearings 15. The rotating shaft 14, the turbine impeller 6, and the compressor impeller 7 rotate around the rotation axis H as a single rotating body 12.

[0018] The turbine housing 4 is provided with an exhaust gas inlet (not shown) and an exhaust gas outlet 10. Exhaust gas discharged from an internal combustion engine (not shown) flows into the turbine housing 4 through the exhaust gas inlet, passes through the vortex flow path 16, and flows into the turbine impeller 6, causing the turbine impeller 6 to rotate. The exhaust gas then flows out of the turbine housing 4 through the exhaust gas outlet 10.

[0019] The compressor housing 5 is provided with an intake port 9 and an exhaust port (not shown). As the turbine impeller 6 rotates as described above, the compressor impeller 7 rotates via the rotary shaft 14. The rotating compressor impeller 7 draws in external air through the intake port 9. This air passes through the compressor impeller 7 and the vortex flow path 17, is compressed, and is discharged from the exhaust port. The compressed air discharged from the exhaust port is supplied to the internal combustion engine described above.

[0020] The turbine 2 of the supercharger 1 will be further described. In the following description, the terms "axial direction," "radial direction," and "circumferential direction" refer to the rotation axis direction (rotation axis H direction), the rotation radial direction, and the rotation circumferential direction of the turbine impeller 6, respectively.

[0021] As in Figure 2 As also shown in FIG, the turbine 2 of the supercharger 1 is provided with a nozzle flow path 19 that connects the vortex flow path 16 to the turbine impeller 6. A plurality of movable nozzle vanes 21 are provided in the nozzle flow path 19. The plurality of nozzle vanes 21 are arranged at equal intervals on a circumference centered on the rotation axis H. Each nozzle vane 21 rotates synchronously about an axis parallel to the rotation axis H. By rotating the plurality of nozzle vanes 21 in this manner, the gaps between adjacent nozzle vanes 21 expand and contract, thereby adjusting the opening of the nozzle flow path 19.

[0022] To drive the nozzle vanes 21 as described above, the turbine 2 includes a variable nozzle unit 20. The variable nozzle unit 20 is embedded inside the turbine housing 4. The variable nozzle unit 20 includes the aforementioned plurality of nozzle vanes 21 and two nozzle rings 23 and 27 that sandwich the nozzle vanes 21 axially. The two nozzle rings 23 and 27 are arranged axially, with the nozzle ring 23 positioned closer to the bearing housing 13 than the nozzle ring 27. The nozzle rings 23 and 27 each have an annular shape centered on the rotation axis H and are arranged to circumferentially surround the turbine impeller 6. The region axially sandwiched between the two nozzle rings 23 and 27 constitutes the aforementioned nozzle flow path 19. The variable nozzle unit 20 also includes a drive mechanism 29 for driving the nozzle vanes 21. The drive mechanism 29 is housed in the space between the nozzle ring 23 and the bearing housing 13 and transmits the driving force from an external actuator (not shown) to the nozzle vanes 21.

[0023] A heat shield 31 is provided between the turbine wheel 6 and the bearing housing 13. The heat shield 31 blocks radiant heat from the high-temperature turbine housing 4, thereby suppressing a temperature rise in the bearing housing 13. The heat shield 31 is annular and circumferentially surrounds the rotating shaft 14. The heat shield 31 is inserted into the central opening of the nozzle ring 23 from the bearing housing 13 side.

[0024] A disc spring 35 (spring member) is sandwiched between the heat shield plate 31 and the bearing housing 13. The disc spring 35 is arranged along a conical surface centered on the rotation axis H, with the rotating shaft 14 inserted through the central hole. One axial end of the disc spring 35 contacts the bearing housing 13, while the other axial end of the disc spring 35 contacts the heat shield plate 31. Furthermore, the disc spring 35 biases the bearing housing 13 and heat shield plate 31 in a direction that moves them axially away from each other. Details of the disc spring 35 will be discussed later.

[0025] Such a disc spring 35 axially biases the variable nozzle unit 20 and the heat shield 31 toward the turbine housing 4. Furthermore, the force of the disc spring 35 presses the variable nozzle unit 20 against the turbine housing 4 and secures its position in the axial direction. Specifically, of the two nozzle rings 23 and 27 of the variable nozzle unit 20, the nozzle ring 23 located on the bearing housing 13 side has a flange 23a formed to extend outward. Conversely, the turbine housing 4 has a ridge 4a formed to receive the flange 23a. Furthermore, the end surface of the flange 23a on the turbine housing 4 side is pressed against the end surface of the ridge 4a on the bearing housing 13 side by the force of the disc spring 35. Furthermore, the flange 23a is allowed to slide radially relative to the ridge 4a, absorbing the radial thermal expansion difference between the variable nozzle unit 20 and the turbine housing 4.

[0026] The disc spring 35 will be further described. Figure 31 is a cross-sectional view schematically showing the vicinity of the disc spring 35 in the supercharger 1. Figure 3 The left side of the middle figure is the turbine housing 4 side, and the right side is the bearing housing 13 side. The shape of the disc spring 35 is drawn more exaggerated than the actual shape.

[0027] like Figure 3 As shown, the disc spring 35 exists along the conical surface of the virtual cone T. The virtual cone T is a cone having the rotation axis H as the cone axis, and the cone bottom surface Tb of the virtual cone T is located closer to the bearing housing 13 than the cone apex Ta.

[0028] like Figure 2 As shown, the disc spring 35 contacts the heat shield 31 at a radially outer contact point (hereinafter referred to as "first contact point P1"). Furthermore, the disc spring 35 contacts the bearing housing 13 at a radially inner contact point (hereinafter referred to as "second contact point P2"). Furthermore, the first contact point P1, where the disc spring 35 contacts the heat shield 31, is located closer to the bearing housing 13 than the second contact point P2, where the disc spring 35 contacts the bearing housing 13.

[0029] Furthermore, to ensure that the heat shield plate 31 contacts the first contact point P1 of the disc spring 35, a protrusion 31a is formed on the outer peripheral edge of the heat shield plate 31 on the bearing housing 13 side. The protrusion 31a extends to a position closer to the bearing housing 13 than the second contact point P2 of the disc spring 35, and the tip of the protrusion 31a contacts the first contact point P1 of the disc spring 35.

[0030] Figure 4 (a) is a cross-sectional view showing a deformed state of the disc spring 35 . Figure 4 (b) is a cross-sectional view showing a deformed state when a conventional disc spring 85 (such as that described in Patent Document 1) is applied to the supercharger 1 for comparison. Figure 4 In (a) and (b), the left side of the figure is the turbine housing 4 side, and the right side is the bearing housing 13 side. In each figure, the shapes of the disc springs 35 and 85 are exaggerated than the actual ones.

[0031] like Figure 4 As shown in (a), the disc spring 35 receives a reaction force F1 from the heat shield 31 that pushes the first contact point P1 toward the bearing housing 13. In addition, the disc spring 35 receives a reaction force F2 from the bearing housing 13 that pushes the second contact point P2 toward the variable nozzle unit 20. Due to the reaction forces F1 and F2, the disc spring 35 is Figure 4As indicated by the double-dotted line in (a), the disc spring 35 is elastically deformed in such a manner that the first contact point P1 and the second contact point P2 are axially separated. Moreover, the disc spring 35 has a reaction force to restore the deformation, and as described above, applies force in the direction of axially expanding the space between the variable nozzle unit 20 and the bearing housing 13. That is, the disc spring 35 is used in a state in which it is elastically deformed to extend in the axial direction by being subjected to a tensile load in the axial direction. In this way, the disc spring 35 is used in a load state opposite to that of a normal disc spring that is elastically deformed to contract in the axial direction by being subjected to a compressive load in the axial direction. By the action of such a disc spring 35, the variable nozzle unit 20 is pressed against the turbine housing 4 and positioned in the axial direction, as described above.

[0032] In contrast, the assumption that Figure 4 The case where the disc spring 85 of the conventional supercharger shown in (b) is applied to the supercharger 1 will be described. In this case, Figure 4 As shown in (b), the disc spring 85 receives a reaction force F1 from the heat shield 31 that pushes the outer peripheral side 85a toward the bearing housing 13. In addition, the disc spring 85 receives a reaction force F2 from the bearing housing 13 that pushes the inner peripheral side 85b toward the variable nozzle unit 20. Due to the above reaction forces F1 and F2, the disc spring 85 is as shown in FIG. Figure 4 As indicated by the two-dot chain line in (b), the outer circumferential side 85a and the inner circumferential side 85b are elastically deformed so that the outer circumferential side 85a and the inner circumferential side 85b approach each other in the axial direction. Furthermore, the disc spring 85 exerts a reaction force intended to restore this deformation, and as described above, it applies force in a direction that increases the distance between the variable nozzle unit 20 and the bearing housing 13 in the axial direction. This force of the disc spring 85 presses the variable nozzle unit 20 against the turbine housing 4, as described above, and positions it in the axial direction.

[0033] Next, the effects of the supercharger 1 of this embodiment equipped with the disc spring 35 described above will be described. In the supercharger 1 in operation, the variable nozzle unit 20 side becomes hot due to the influence of the high-temperature gas, while the bearing housing 13 side is cooled by water cooling, oil cooling, etc. and has a relatively low temperature. For example, a cooling water flow path 13a is formed in the bearing housing 13 for cooling (see Figure 2 ).

[0034] Under this condition, assuming the use Figure 4In the case of the conventional disc spring 85 of (b), the outer peripheral side 85a of the disc spring 85 contacts the heat shield 31 on the variable nozzle unit 20 side and has a relatively high temperature. In contrast, the inner peripheral side 85b contacts the bearing housing 13 and has a relatively low temperature. As a result, a temperature distribution is generated in the disc spring 85, with the outer peripheral side being high and the inner peripheral side being low. Moreover, according to this temperature distribution, the outer peripheral side of the disc spring 85 is circumferentially elongated compared to the inner peripheral side. As a result, the disc spring 85 is deformed ( Figure 4 The spring load of the disc spring 85 urging the variable nozzle unit 20 is reduced due to the thermal deformation.

[0035] On the other hand, in the supercharger 1 of the present embodiment using the disc spring 35, as described above, the temperature of the first contact point P1 on the outer circumference side is relatively high, and the temperature of the second contact point P2 on the inner circumference side is relatively low. Therefore, as described above, a temperature distribution is generated in the disc spring 35, with the outer circumference side being high and the inner circumference side being low. In addition, due to this temperature distribution, deformation ( Figure 4 Thermal deformation occurs in the direction opposite to the double-dashed line (a) of FIG. Specifically, the thermal deformation of the disc spring 35 at this time is in the direction of the push-back reaction forces F1 and F2. Consequently, this thermal deformation further increases the spring load of the disc spring 35 urging the variable nozzle unit 20. Therefore, the supercharger 1 of this embodiment can suppress a decrease in the spring load of the disc spring 35 at high temperatures.

[0036] In addition, assuming the Figure 4 In this case, the disc spring 85 of (b) requires designing its shape by fine-tuning its shape while repeatedly performing thermal deformation analysis, taking into account the effects of thermal deformation of components surrounding the disc spring 85 and minimizing spring load reduction. Furthermore, since this design cycle must be repeated every time the supercharger 1 model is changed, the design process cannot be said to be efficient. In contrast, the disc spring 35 of this embodiment simplifies this complex design process.

[0037] Furthermore, according to the disc spring 35 of this embodiment, the radial stress generated in the disc spring 35 during deformation due to the reaction forces F1 and F2 is tensile stress, thereby also having the effect of preventing the disc spring 35 from buckling.

[0038] Furthermore, in the supercharger 1 of this embodiment, the presence of the heat shield 31 reduces heat input to the disc springs 35. This reduces the Young's modulus of the disc springs 35, which decreases due to the high temperature of the disc springs 35, and further reduces the reduction in spring load. Furthermore, the possibility of creep and a decrease in yield stress in the disc springs 35 due to the high temperature of the disc springs 35 is reduced.

[0039] Furthermore, in the supercharger 1 of this embodiment, axial positioning of the variable nozzle unit 20 is achieved by pressing the flange 23a of the nozzle ring 23 against the ridge 4a of the turbine housing 4. During operation of the supercharger 1, the ridge 4a displaces due to thermal deformation of the turbine housing 4, and deformation of the variable nozzle unit 20 occurs in conjunction with the displacement of the ridge 4a.

[0040] It is believed that during operation of the supercharger 1, the closer to the joint with the bearing housing 13, the smaller the displacement caused by thermal deformation of various parts of the turbine housing 4. The nozzle ring 23 of the variable nozzle unit 20 is located relatively close to the bearing housing 13 within the variable nozzle unit 20. Consequently, the ridges 4a of the turbine housing 4 are also located close to the joint with the bearing housing 13. Therefore, during operation of the supercharger 1, the displacement of the ridges 4a is minimized, and as a result, the deformation of the variable nozzle unit 20 caused by the displacement of the ridges 4a is also minimized.

[0041] The supercharger disclosed herein, represented by the above-described embodiment, can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. For example, in the above-described embodiment, the supercharger 1 includes a heat shield 31. However, the heat shield 31 can be omitted, and the spring member 35 can be configured to directly contact the nozzle ring 23. In this case, the shape of the nozzle ring 23 is modified so that the spring member 35 contacts the nozzle ring 23 (the variable nozzle unit side) at a first contact point P1 on its outer circumference and contacts the bearing housing 13 side at a second contact point P2 on its inner circumference. The first contact point P1 is located closer to the bearing housing than the second contact point P2 in the direction of the rotation axis. For example, in this case, instead of the above-described ridge 31a, the nozzle ring 23 can be provided with a ridge that extends closer to the bearing housing 13 than the second contact point P2 of the spring member 35, with the tip contacting the first contact point P1 of the spring member 35.

[0042] Description of reference numerals:

[0043] 1…variable capacity supercharger; H…rotation axis; 4…turbine housing; 13…bearing housing; 20…variable nozzle unit; 23…nozzle ring; 27…nozzle ring; 31…heat shield; 35…disc spring (spring component); 23a…flange; 4a…ribbed portion; T…imaginary cone; P1…first contact point; P2…second contact point.

Claims

1. A supercharger, characterized in that: have: a variable nozzle unit disposed between the turbine housing and the bearing housing; and an annular spring member disposed between the variable nozzle unit and the bearing housing and biasing the variable nozzle unit and the bearing housing in a direction that expands the space between the variable nozzle unit and the bearing housing in the direction of the rotation axis; The spring member is a disc spring that contacts the variable nozzle unit at a first contact point on the outer peripheral side and contacts the bearing housing at a second contact point on the inner peripheral side. In the direction of the rotation axis, the first contact point is located closer to the bearing housing than the second contact point. The spring member exists along a conical surface of an imaginary cone having the rotation axis as a conical axis.

2. The supercharger according to claim 1, characterized in that A heat shield is further provided, which is sandwiched between the variable nozzle unit and the spring member in the direction of the rotation axis and shields the spring member from heat from the turbine. The first contact point of the spring member is in contact with the heat shield.

3. The supercharger according to claim 1 or 2, characterized in that: The variable nozzle unit has two nozzle rings arranged along the direction of the rotation axis. Of the two nozzle rings, the nozzle ring located on the bearing housing side is pressed against a predetermined portion of the turbine housing in the direction of the rotation axis by the biasing force of the spring member.

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