VARIABLE GEOMETRY TURBINE AND CHARGER

Abstract

Turbine (10) with variable geometry, comprising: a turbine impeller (12) configured to rotate about an axis line; a turbine casing (30) configured to accommodate the turbine runner (12) and forming a constriction passage (32) and a spiral flow channel (34) on an outer circumferential side of the turbine runner (12), the spiral flow channel (34) being connected to the constriction passage (32); and a width-change mechanism (50) in which a width-change part (52), which changes a passage width of the constriction passage (32) along a circumferential direction of the turbine impeller (12), is movable in a width direction of the passage width, wherein the width-changing part (52) continuously changes the passage width of the constriction passage (32) along the circumferential direction of the turbine (10); wherein the width-changing mechanism (50) comprises the following a cylindrical element with a cylindrical shape extending in the axial direction and having a change section in which one end of the cylindrical shape is inserted into the constriction passage (32) in the axial direction and in which an edge position formed at one end changes along a circumferential direction of the cylindrical shape, and a drive unit configured to move the cylindrical element in the axis direction, where the change section is the width change part (52).

Description

[Technical field]

[0001] The present disclosure relates to a variable geometry turbine and a turbocharger. [Technical background]

[0002] A turbocharger turbine, for example one used in a motor vehicle, operates across a wide range of output levels, from low to high, depending on the engine output. Therefore, there is a need to improve performance at every output level.

[0003] To meet this need, there is, for example, a variable geometry turbine (VG) that can adjust the flow characteristics in accordance with the engine output.

[0004] As a turbine capable of adjusting its flow characteristics according to the motor output, PTL 1 discloses a turbine featuring a spiral flow channel divided into a main spiral and a sub-spiral. A cylindrical slide valve is used within the spiral flow channel to stop the sub-spiral in accordance with the motor's operating condition. [Citation list][Patent literature]

[0005] [PTL 1] DE 42 32 400 C1 relates to an adjustable flow guide apparatus for an impeller of an exhaust gas turbocharger of an internal combustion engine, wherein the flow guide apparatus comprises an annular insert between a spiral guide channel of the exhaust gas turbocharger and the impeller with radial or diagonal flow direction. DE 10 2011 120 555 A1 relates to a guide grid for a turbine of an exhaust gas turbocharger, with a plurality of guide elements arranged in a guide area of ​​the guide grid. DE 11 2011 103 362 T5 relates to an exhaust gas turbocharger with a compressor; with a turbine which has a turbine wheel with a radial flow area and a semi-axial flow area. PTL 1: Japanese Utility Model Laid-Open No. JP S61-66628 U. [Summary of the invention][Technical problem]

[0006] On the other hand, engine output has improved in recent years, and exhaust gas temperatures have tended to increase. In such a case, a variable-speed turbine with a complex linkage mechanism exhibits problems regarding the failure rate and the reliability of the components that form the linkage mechanism.

[0007] In general, the fluid inflow to a turbine impeller is large, so the flow angle near the beginning of the turn (fluid inlet) of a spiral flow channel tends to be larger. Conversely, a flow angle near the end of the turn of a spiral flow channel tends to be small because the flow velocity of an exhaust gas is reduced due to frictional losses at the wall surface forming the spiral flow channel. The same applies to the turbines described in PTL 1 and VG.

[0008] The present disclosure was made in view of such circumstances and intends to provide a variable geometry turbine which can change the flow characteristics of a turbine in accordance with the engine output with a simple structure and which can adjust the flow angle of a fluid flowing into a turbine impeller to any angle in the circumferential direction of the turbine impeller, and to provide a supercharger which incorporates the variable geometry turbine. [Solution to the problem]

[0009] The aforementioned disadvantages are at least partially solved by a turbine according to claim 1.

[0010] To solve the aforementioned problems, the variable geometry turbine and the turbocharger incorporating the variable geometry turbine of the present disclosure employ the following measures.

[0011] In particular, a variable geometry turbine according to one aspect of the present disclosure comprises a turbine impeller configured to rotate about an axis line, a turbine casing configured to accommodate the turbine impeller and forming a constriction passage and a scroll flow channel on an outer circumferential side of the turbine impeller, the scroll flow channel being connected to the constriction passage, and a width-change mechanism in which a width-change element, which changes a passage width of the constriction passage along a circumferential direction of the turbine impeller, is movable in a width direction of the passage width.

[0012] The variable geometry turbine according to the aspect comprises a turbine runner configured to rotate about an axis line, a turbine casing configured to accommodate the turbine runner and form a constriction passage and a spiral flow channel on an outer circumferential side of the turbine runner, and a width-change mechanism in which a width-change part, which changes a passage width of the constriction passage along a circumferential direction of the turbine runner, is movable in a width direction of the passage width.

[0013] Accordingly, the width of the constriction passage is modified by the width-change mechanism (i.e., the flow channel area of ​​the constriction passage is adjusted), thus making it possible to adjust the flow rate of a fluid (e.g., exhaust gas from an engine) flowing from the spiral flow channel into the turbine impeller. In this way, the flow characteristics of a turbine can be modified depending on the engine output with a simple structure, without requiring a complex structure like that of VG turbines. Compared to the VG turbine, the simplified structure allows for a reduction in the number of components, thereby decreasing the failure rate and improving reliability.

[0014] Furthermore, the passage width of the constriction passage is changed by the width change part along the circumferential direction of the turbine runner, and it is thus possible to adjust the flow angle of a fluid flowing into a turbine runner to any angle in the circumferential direction of the turbine runner.

[0015] The flow angle is larger, for example, near the beginning of the spiral winding (exhaust gas inlet side) of the spiral flow channel, due to the high fluid inflow into the turbine runner. Conversely, the flow angle is smaller near the end of the spiral flow channel because the flow velocity decreases due to friction losses at the inner wall of the turbine casing. At this point, the width of the constriction passage is modified so that it gradually increases from the beginning of the spiral winding to the end of the spiral flow channel winding, thus preventing excessive fluid inflow to the turbine runner near the beginning of the winding and a reduction in fluid flow velocity near the end of the winding.In other words, it is possible to avoid a non-uniformity of the flow angles in the circumferential direction of the turbine impeller in order to obtain a uniform distribution of the flow angles in the circumferential direction of the turbine impeller.

[0016] In the variable geometry turbine according to one aspect of the present disclosure, the width-changing part also continuously changes the passage width of the constriction passage along a circumferential direction of the turbine.

[0017] In accordance with the variable geometry turbine design, the width-changing element can continuously alter the width of the constriction passage along the circumference of the turbine runner. Consequently, the width of the constriction passage can be varied uniformly along the circumference of the turbine runner, thus preventing abrupt changes in the flow rate of the fluid entering the turbine runner along its circumference.

[0018] Furthermore, in the variable geometry turbine according to one aspect of the present disclosure, the width-changing mechanism comprises a cylindrical element with a cylindrical shape extending in the axis direction and having a changing section in which one end of the cylindrical shape is inserted into the constriction passage in the axis direction and in which an edge position formed at one end changes along a circumferential direction of the cylindrical shape, as well as a drive unit configured to move the cylindrical element in the axis direction, and the changing section is the width-changing part.

[0019] In accordance with the variable geometry turbine design, the width-change mechanism comprises a cylindrical element with a cylindrical shape extending along the axis and featuring a change section. In this section, one end of the cylindrical shape is inserted into the constriction passage along the axis, and an edge position formed at one end changes along the circumference of the cylindrical shape. A drive unit is configured to move the cylindrical element along the axis. The change section is the width-change portion. Accordingly, the cylindrical element, which includes the change section, is inserted into the constriction passage by the drive unit, thus reducing the flow channel area for the entire constriction passage.Furthermore, the passage width of the constriction passage along the circumferential direction of the turbine impeller can be changed by the modification section.

[0020] Furthermore, according to one aspect of the present disclosure, a charger comprises the variable geometry turbine described above and a compressor with a compressor wheel rotated by the turbine wheel.

[0021] A supercharger according to this aspect includes the variable geometry turbine described above and a compressor with a compressor impeller that is rotated by the turbine impeller. [Advantageous effects of the invention]

[0022] According to a variable geometry turbine and a supercharger as described in the present disclosure, it is possible to change the flow characteristics of a turbine in accordance with the engine output using a simple structure, and it is possible to adjust the flow angle of a fluid flowing into a turbine impeller to any angle in the circumferential direction of the turbine impeller. [Brief description of the drawings] [ Fig. 1] Fig. Figure 1 is a vertical sectional view of a turbine with variable geometry according to an embodiment of the present disclosure. [ Fig. 2] Fig. 2 is a cross-sectional view taken along a Fig. Section line II shown in section 1. [ Fig. 3] Fig. Figure 3 is a diagram illustrating the change in passage width through a width change section in a narrowing passage that develops in the circumferential direction. [ Fig. 4] Fig. Figure 4 is a diagram illustrating the change in passage width through a width change section in a narrowing passage running in the circumferential direction. [ Fig. 5] Fig. Figure 5 is a diagram illustrating a state in which a constricting passage developing in a circumferential direction is fully opened by the width change portion. [ Fig. 6] Fig. Figure 6 is a diagram that represents a configuration of a cylindrical element. [ Fig. 7] Fig. 7 is a diagram drawn by someone in Fig. 6. Arrow A is shown from the perspective. [ Fig. 8] Fig. Figure 8 is a developed view of the cylindrical element. [Description of the embodiments]

[0023] A variable geometry turbine and a turbocharger according to an embodiment of the present disclosure are described below with reference to the drawings.

[0024] First, a configuration of a variable geometry turbine 10 and a turbocharger is described.

[0025] As in Fig. As shown in Figure 1, the variable geometry turbine 10 has a turbine wheel 12 and a turbine housing 30 that accommodates the turbine wheel 12.

[0026] The turbine impeller 12 has a hub 14 on which a plurality of blades 16 are formed and is at one end (in Fig. 1 the right end) of a rotor shaft 18 attached.

[0027] The rotor shaft 18 is mounted on a bearing (not shown) so that it can rotate about an axis X. This allows the turbine impeller 12 to rotate about the axis X.

[0028] A compressor impeller (not shown) is located at the other end (right end in) Fig. 1) attached to the rotor shaft 18. Accordingly, the turbine impeller 12 and the compressor impeller are connected to each other via the rotor shaft 18, and the compressor impeller is rotated by the rotation of the turbine impeller 12.

[0029] The compressor impeller forms a compressor (not shown) that compresses air drawn in from the outside, and the variable geometry turbine 10 and the compressor (not shown) form the supercharger.

[0030] As in Fig. 1 and Fig. As shown in Figure 2, the turbine housing 30 is a housing that accommodates the turbine impeller 12 and is configured to form a constriction passage 32 and a spiral flow channel 34 on the outer circumferential side of the turbine impeller 12.

[0031] As in Fig. As shown in Figure 2, the spiral flow channel 34 is a spiral-shaped flow channel extending circumferentially around the turbine impeller 12, with the flow channel area gradually decreasing from an exhaust gas inlet side 36 of the turbine housing 30. In this state, the side of the exhaust gas inlet 36 is the beginning of the spiral flow channel 34, and the side in the direction of exhaust gas flow is the end of the spiral flow channel. Consequently, the flow channel area of ​​the spiral flow channel 34 gradually decreases from the beginning of the spiral flow channel to the end of the spiral flow channel.

[0032] In Fig. 2 The angle near a tongue section 31 is defined as 0 degrees for the purpose of illustration, the angle increases along an exhaust flow direction, and the angle at the end of the winding of the spiral flow channel 34 is defined as 360 degrees.

[0033] As in Fig. 1 and Fig. As shown in Figure 2, the constriction passage 32 is a flow channel formed circumferentially on the outer circumferential side of the turbine impeller 12 and connected to the spiral flow channel 34. The passage width of the constriction passage 32 formed from the turbine casing 30 is constant along the circumferential direction of the turbine impeller 12.

[0034] The constriction passage 32 connects the space of the turbine housing 30, which accommodates the turbine wheel 12, and the spiral flow channel 34.

[0035] The operation of the variable geometry turbine 10 and the turbocharger is described below.

[0036] Exhaust gas emitted by an engine (not shown) flows from the exhaust gas inlet 36 of the turbine housing 30 into the spiral flow channel 34.

[0037] The exhaust gas flowing in the spiral flow channel 34 flows through the spiral flow channel 34 and flows via the constriction passage 32 into the turbine wheel 12.

[0038] At this point, the flow velocity of the exhaust gas flowing from the spiral flow channel 34 into the turbine wheel 12 depends on the flow channel area of ​​the spiral flow channel 34 and the passage width of the constriction passage 32.

[0039] The exhaust gas flowing into the turbine runner 12 flows between the majority of blades 16 of the turbine runner 12 and expands to rotate the turbine runner 12 around the axis line X.

[0040] The exhaust gas that has passed through the turbine impeller 12 flows through an outlet flow channel 42, which is formed inside the turbine housing 30, and is discharged from an exhaust gas outlet 40 to the outside of the variable geometry turbine 10.

[0041] On the other hand, the compressor impeller (not shown) is rotated around the axis line X in response to the rotation of the turbine impeller 12.

[0042] The compressor compresses air through the rotation of its impeller. The compressed air is then supplied to the motor (not shown).

[0043] Next, a width change mechanism 50 is described, which is provided in the variable geometry turbine 10.

[0044] As in Fig. 3 to Fig. As shown in Figure 5, the width change mechanism 50 is a mechanism provided on the turbine 10 with variable geometry and can move a width change part 52 in the width direction, which continuously changes the passage width of the narrowing passage 32 along the circumferential direction of the turbine impeller 12.

[0045] It should be noted that the term "continuous", as used here, refers to a smoothly connected line shape such as a curved line, which differs from a shape with a sharp change such as a large step.

[0046] With this width-changing part 52, the exhaust gas flow rate flowing from the spiral flow channel 34 into the turbine wheel 12 can be changed along the circumferential direction of the turbine wheel 12.

[0047] For example, in Fig. 3 The passage width of the constriction passage 32 is gradually widened by the width change section 52 from the beginning of the turn to the end of the turn of the spiral flow channel 34. This allows the exhaust gas flow entering the turbine runner 12 to be reduced more significantly on the side of the beginning of the turn of the spiral flow channel 34, compared to a case in which the passage width is constant along the circumferential direction of the turbine runner 12.

[0048] It should be noted that the in Fig. 3 shown θ1 to θ3 in Fig. The θ1 to θ3 shown in 2 correspond to the winding angles of the spiral flow channel 34, which correspond to θ1 < θ2 < θ3. It should be noted that the in Fig. 2 and Fig. The 3 depicted flow channel areas are not accurately represented and θ1 to θ3 in Fig. 2 and θ1 to θ3 in Fig. 3 do not exactly match.

[0049] The change in passage width provided by the width change part 52 is not based on the one in Fig. 2 and Fig. The 3 variants shown are limited and can be changed in any way. In particular, the shape of the width-changing element 52 can be changed in any way, and it is thus possible to change the exhaust gas flow rate flowing from the spiral flow channel 34 into the turbine impeller 12 in any way along the circumferential direction of the turbine impeller 12.

[0050] As in Fig. 3 to Fig. As shown in Figure 5, the width-changing section 52 described above is movable along the width direction. This allows the flow channel area to be adjusted for the entire constriction passage 32 along the circumferential direction of the turbine impeller 12.

[0051] For example, as in Fig. Figure 5 shows a portion of the constriction passage 32 closed off by the constriction passage 32, in which a passage along the circumferential direction of the turbine runner 12 is fully open (i.e., the passage width is constant along the entire circumferential direction of the turbine runner 12), as shown in Fig. 3 and Fig. Figure 4 is shown (indicated by a hatched section within it). This makes it possible to change the flow channel area for the entire constriction passage 32. In this way, the exhaust gas flow rate flowing from the entire spiral flow channel 34 into the turbine impeller 12 can be adjusted in accordance with the engine output.

[0052] Especially when the engine is operating at high power, the narrowing passage 32 is fully open, as shown in Fig. 5 is shown, and it is thus possible to draw the exhaust gas from the engine to the variable geometry turbine 10 without any loss. Since the exhaust gas flow rate is low when the engine is operated at low power, part of the constriction passage 32 is closed, as shown in Fig. 3 and Fig. 4 shown, and it is therefore possible to increase the flow velocity of the exhaust gas flowing into the turbine wheel 12 in order to rotate the turbine wheel 12 efficiently.

[0053] As in Fig. 6 and Fig. As shown in Figure 7, such a width-changing mechanism 50 has a cylindrical element 54 and a drive unit that moves the cylindrical element 54 in the direction of the axis line X.

[0054] The cylindrical element 54 is a cylindrical shape that surrounds the turbine impeller 12 from the outer circumferential side, and has an end face (left end face in Fig. 5) The cylindrical shape can be inserted into the narrowing passage 32 along the axis line X-direction.

[0055] The cylindrical element 54 has a section (a modification section 52) in which an edge position at a insertion end face (an end face described above) changes continuously in the axis line X direction along the circumferential direction of the cylindrical shape.

[0056] The modification section 52 corresponds to the width modification section 52 described above, and the edge shape (degree of change of the edge position) of the modification section 52 can be determined as any shape, taking into account a target passage width of the narrowing passage 32.

[0057] Fig. Figure 8 shows a developed view of the cylindrical element 54. To form the width-changing section 52 as it appears, for example, in Fig. As shown in 3, it can be designed so that the in Fig. 8 Edge shape of the modification section 52 of the cylindrical element 54 shown in Fig. The form of the width change part 52 shown in 3 corresponds to this.

[0058] As in Fig. As shown in Figure 6, the cylindrical element 54 can be moved in the direction of the axis line X by the drive unit (not shown). This allows the insertion quantity of the changeover section 52 to be adjusted with respect to the constriction passage 32. This is how it is, as shown in Fig. 3 to Fig. As shown in Figure 5, it is possible to fully open or partially close the narrowing passage 32.

[0059] The advantageous effects described below are achieved in the present embodiment.

[0060] The passage width of the constriction 32 is changed by the width-change mechanism 50 (i.e., the flow channel area of ​​the constriction 32 is adjusted), thus making it possible to adjust the flow rate of an exhaust gas flowing from the spiral flow channel 34 into the turbine impeller 12. This allows the flow characteristics to be changed depending on the engine output with a simple structure, without the need for a complex structure like that used in VG turbines. Compared to a VG turbine, the simplified structure reduces the number of components, thereby lowering the failure rate and improving reliability.

[0061] Furthermore, the passage width of the constriction passage 32 is changed by the width-changing part 52 along the circumferential direction of the turbine runner 12, and it is thus possible to adjust the flow angle of the exhaust gas flowing into the turbine runner 12 to any angle in the circumferential direction of the turbine runner 12.

[0062] The flow angle is larger, for example, near the beginning of the spiral flow channel 34 because the turbine impeller 12 is subjected to a strong flow. In contrast, the flow angle is small near the end of the spiral because the flow velocity is reduced due to friction losses on an inner wall surface of the turbine casing 30 that forms the spiral flow channel 34. Consequently, uneven flow angles can occur around the circumference of the turbine impeller 12, which can lead to a degradation in the performance of the variable geometry turbine 10.The passage width of the constriction 32 is modified such that it gradually widens from the beginning of the turn to the end of the turn of the spiral flow channel 34. This prevents excessive fluid flow to the turbine runner 12 near the beginning of the turn and a reduction in fluid flow velocity near the end of the turn, thus ensuring a consistent exhaust gas flow rate. Consequently, it is possible to avoid uneven flow angles around the circumference of the turbine runner 12, thereby achieving a uniform distribution of flow angles around the circumference of the turbine runner 12 and improving the performance of the variable geometry turbine 10.

[0063] Furthermore, the width-changing element 52 continuously alters the passage width of the constriction passage 32 along the circumferential direction of the turbine runner 12. Accordingly, the passage width of the constriction passage 32 can be changed uniformly along the circumferential direction of the turbine runner 12, and it is thus possible to prevent a sharp change in the flow rate of the fluid flowing into the turbine runner 12 in the circumferential direction.

[0064] It should be noted that, as described above, the flow velocity of the exhaust gas flowing from the spiral flow channel 34 into the turbine impeller 12 depends on the flow channel area of ​​the spiral flow channel 34 and the passage width of the constriction passage 32. Accordingly, taking into account the change in the flow channel area along the winding direction of the spiral flow channel 34, the shape of the change in width section 52 is determined in order to achieve an optimal distribution of the flow angles. [List of reference symbols] 10 Variable geometry turbine 12 Turbine wheel 14 hub 16 shovels 18 Rotor shaft 30 turbine housings 31 Tongue section 32 Narrowing Passage 34 Spiral flow channel 36 Exhaust gas inlet 40 Exhaust outlet 42 Outlet flow channel 50 Width change mechanism 52 Width change section (change section) 54 cylindrical element X-axis line

Claims

[1] Turbine (10) with variable geometry, comprising: a turbine impeller (12) configured to rotate about an axis line; a turbine casing (30) configured to accommodate the turbine runner (12) and forming a constriction passage (32) and a spiral flow channel (34) on an outer circumferential side of the turbine runner (12), the spiral flow channel (34) being connected to the constriction passage (32); and a width-change mechanism (50) in which a width-change part (52), which changes a passage width of the constriction passage (32) along a circumferential direction of the turbine impeller (12), is movable in a width direction of the passage width, wherein the width-changing part (52) continuously changes the passage width of the constriction passage (32) along the circumferential direction of the turbine (10); wherein the width-changing mechanism (50) comprises the following a cylindrical element with a cylindrical shape extending in the axial direction and having a change section in which one end of the cylindrical shape is inserted into the constriction passage (32) in the axial direction and in which an edge position formed at one end changes along a circumferential direction of the cylindrical shape, and a drive unit configured to move the cylindrical element in the axis direction, where the change section is the width change part (52). [2] Charger, including: the turbine (10) with variable geometry according to claim 1; and a compressor with a compressor impeller that is rotated by the turbine impeller (12).

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