JP3605398B2 - Variable capacity turbocharger - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable capacity turbocharger such as a supercharger, a small gas turbine, an expander turbine, and the like.
[0002]
[Prior art]
A conventional variable capacity turbocharger will be described with reference to FIGS. FIG. 6 is a longitudinal sectional view of a general variable capacity turbocharger, FIG. 7 is an explanatory view of the operation of the nozzle vane as viewed from the direction of arrows AA in FIG. 6, and FIG. 8 is a pressure action in the nozzle vane showing the same surface as FIG. FIG. 9 is a sectional view of a nozzle vane of a conventional hydrodynamic design showing the same surface as that of FIG. 7, (a) is a state in which the nozzle vane is closed, and (b) is an enlarged view of a sectional shape of the nozzle vane. It is. FIG. 10A is an explanatory view of the position of the pivot in the nozzle vane, and FIG. 10B is an explanatory view of a moment around the pivot acting on the nozzle vane of the conventional hydrodynamic design.
[0003]
As shown in FIG. 6, generally, the variable-capacity turbocharger 30 surrounds a compressor wheel 34 attached to one end of the turbine rotor 33 by inserting a turbine rotor 33 rotationally supported by a bearing 32 into a bearing housing 31. A compressor casing 35 is attached to the bearing housing 31 so as to cover it. On the other hand, a turbine wheel 36 is attached to the other end of the turbine rotor 33, and a turbine casing 37 is attached to the bearing housing 31 so as to surround and cover the turbine wheel 36.
[0004]
A scroll passage 40 is formed inside the turbine casing 37 so as to surround the outer periphery of the turbine wheel 36 around the rotation axis 41 of the turbine rotor 33. On the outer peripheral side of the scroll passage 40, an exhaust gas inlet 38 is provided substantially along a tangential direction of the scroll passage 40, and an exhaust gas outlet 39 is provided along a rotation axis 41 of the turbine rotor 33.
[0005]
Exhaust gas g as a driving fluid of the variable capacity turbocharger 30 enters the scroll passage 40 from the exhaust gas inlet 38, passes through the scroll passage 40, and is provided on the inner peripheral side of the scroll passage 40 at equal pitches in the circumferential direction at the same pitch. The flow rate is variably adjusted by 1 and flows into the turbine wheel 36, drives the turbine wheel 36 to rotate, and is discharged from the exhaust gas outlet 39. On the other hand, the compressor wheel 34 is driven to rotate by a turbine wheel 36 and is used for pumping air a and the like.
[0006]
The nozzle vane 1 is attached to the nozzle mount 2 by a pivot 3 so as to be freely rotatable, and is rotatably controlled by a variable nozzle mechanism 4. A nozzle throat 5 into which g flows is formed, and the opening degree of the flow path of the nozzle throat 5 is controlled by the rotation of the nozzle vane 1 around the pivot 3.
[0007]
6, the pivots 3 of the nozzle vane 1 are located at equal intervals on a pivot pitch circle 6 around the rotation axis 41, and the nozzle vane 1 is connected to the pivot 3 as shown in FIG. When the exhaust gas g is at a small flow rate, the nozzle throat 5 is closed in a direction shown in (a) at a small flow rate, and when the exhaust gas g is at a large flow rate, the nozzle throat 5 is opened in a direction shown in (b). Is controlled to rotate.
[0008]
As shown in FIG. 8, with the nozzle vane 1 and the nozzle throat 5 formed therebetween, the scroll passage 40 on the outer peripheral side becomes the high-pressure side Zp by the exhaust gas g sent as the driving fluid, and the turbine on the inner peripheral side. The wheel 36 becomes the low-pressure side Zn, and generates a static pressure distribution around the nozzle vane 1 as exemplified by the isobar 7 in the drawing.
[0009]
Therefore, due to the pressure difference between the static pressure applied to the pressure surface 1p of the nozzle vane 1 in contact with the high pressure side Zp and the static pressure applied to the negative pressure surface 1n in contact with the low pressure side Zn, the nozzle at the front edge 1a side of the pivot 3 of the nozzle vane 1 A moment M (-) in the closing direction of the throat 5 is generated, and a moment M (+) in the opening direction is generated on the trailing edge 1b side.
[0010]
On the other hand, as shown in FIG. 9A, the nozzle vane 1 closes the nozzle throat 5 so that the front edge 1 a side and the rear edge 1 b side of the adjacent nozzle vane 1 overlap to some extent with the overall length L of the nozzle vane 1. The overlap length Lo in the cross section differs depending on the length L of the nozzle vanes 1, the number of nozzle vanes 1, the radius of the pivot pitch circle 6, the model, and the like.
[0011]
For example, when the nozzle vane length L = 16 mm, the number of nozzle vanes N = 12, and the pivot pitch circle radius R = 26.26 mm, the overlapping length Lo = (L−2πR / N) ≒ 0.14L.
[0012]
In addition, as shown in FIG. 9 (b), the leading edge 1a of the conventional nozzle vane 1 has a relatively large radius so that fluid separation does not occur so that the pressure loss is as small as possible and the efficiency is high. The pressure surface is formed smoothly from the leading edge 1a to the trailing edge 1b along the warp center line 8 of the airfoil of the nozzle vane 1. 1p And suction surface 1n Is designed to be formed.
[0013]
The nozzle vane 1 shown in FIG. 9 (b) is a curved back vane in which the center line 8 of the airfoil is a curved line. The vane surface shape of the standard design nozzle vane is such that the leading edge is formed with a relatively large radius to avoid fluid separation so that the hydrodynamic pressure drop is as small as possible and the efficiency is high. It is designed so that the pressure surface and the suction surface are formed smoothly along the centerline of the airfoil toward the trailing edge. In the present specification, such a conventional nozzle vane designed to minimize the pressure loss in terms of hydrodynamics and increase the efficiency is referred to as a "hydrodynamically designed nozzle vane".
[0014]
In determining the position of the pivot 3, in order to preferably maintain the fluid characteristics of the flow of the exhaust gas g with the downstream turbine wheel 36, it is necessary to reduce the moving distance of the trailing edge 1b due to the rotation around the pivot 3. Preferably, usually, the distance Lp from the trailing edge 1b to the pivot 3 is often set to about 0.5L or less than 0.5L.
[0015]
However, in the conventional nozzle vane 1 of hydrodynamic design at such a position of the pivot 3, the closing moment M (-) due to the static pressure acting on the leading edge 1a side and the opening moment M acting on the trailing edge 1b side. In the balance with (+), the closing moment M (-) is set to be superior or hand However, the balance varies due to the static pressure distribution and the variation thereof due to the opening degree of the nozzle vane 1, and the direction of the total moment M is changed.
[0016]
When the direction of the moment M acting on the nozzle vane 1 is switched, the control position and control characteristics are not constant due to the mechanical and control hysteresis of the variable nozzle mechanism 4 for controlling the rotation of the nozzle vane 1, and the nozzle control of the variable capacity turbocharger is not performed. There was a risk of causing a problem in accuracy. If the closing moment M (−) is set to be superior, and if a drive system such as an actuator of the variable nozzle mechanism 4 fails, the nozzle flow path is closed and the function of the variable capacity turbocharger stops. There was also the possibility that the problem that it might occur.
[0017]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the problem in the variable displacement turbocharger having the nozzle vane 1 of the conventional hydrodynamic design as described above, and has been made by the present inventor for the present invention. The result of studying the state of the moment M acting on the nozzle vane 1 will be described with reference to FIG.
[0018]
FIG. 10A shows the shape of the nozzle vane 1 of the conventional hydrodynamic design and the positions P1 to P5 of the pivot 3 set experimentally. When the total length of the nozzle vane 1 is L, the pivot 3 Of the positions P1 to P5 from the trailing edge 1b are Lp５0.17L at P1, Lp ≒ 0.37L at P2, Lp ≒ 0.5L at P3, Lp ≒ 0.63L at P4, and Lp ≒ 0.63L at P4. Lp ≒ 0.75L.
[0019]
Because of the overlapping length Lo of the front edge 1a and the rear edge 1b of the nozzle vane 1, the position of the pivot 3 is not provided much at the front edge 1a side or the rear edge 1b side. The range of P5 is conceivable.
[0020]
FIG. 10B is a graph of a test result of a moment around the pivot 3 (positions P1 to P5) acting on the nozzle vane 1 at the medium opening degree of the conventional nozzle vane 1 described above.
[0021]
As shown in FIG. 10B, if the pivot 3 is located on the leading edge 1a side from P4 (Lp ≒ 0.63L), the moment M becomes positive (opening direction), and the moment in the opening direction is applied to the nozzle vane 1. In the vicinity of P4 (Lp ≒ 0.63L), the moment M may be unstable due to the positive / negative equilibrium. When Lp is less than, for example, P3 (Lp ≒ 0.50L), the moment M becomes It was always negative (close direction), and it was found that each had the above-mentioned problems.
[0022]
Thus, the pivot 3 may be positioned closer to the leading edge 1a than P4 (Lp ≒ 0.63L). On the other hand, if the pivot 3 is too far from the trailing edge 1b, the pivot 3 is connected to the downstream turbine wheel 36 as described above. Is not preferable in terms of fluid characteristics of the flow of the exhaust gas g.
[0023]
Therefore, even if the pivot 3 is installed at a position closer to the trailing edge 1b, at least at P3 (Lp ≒ 0.50L), the moment M is always positive (opening direction), and the opening direction moment acts on the nozzle vane 1, and the moment It is desirable to have a variable capacity turbocharger 30 having a nozzle vane 1 such that M always acts in the direction of rotating the leading edge 1a of the nozzle vane 1 toward the scroll passage 40 side.
[0024]
The present invention has been made based on such knowledge, and maintains the moment acting on the nozzle vane in the positive direction (opening direction) while acting in the direction of rotating the front edge of the nozzle vane toward the scroll passage. An object of the present invention is to provide a variable displacement turbocharger in which the pivot position can be closer to the trailing edge, the operability and controllability of the nozzle vanes are good, and the fluid characteristics of the flow of exhaust gas from the nozzle vanes to the turbine wheel are good. Is what you do.
[0025]
[Means for Solving the Problems]
(1) The present invention has been made to solve the above-described problems, and as a first means, a scroll passage surrounding a turbine wheel and introducing a driving fluid, and an inner periphery of the scroll passage. A plurality of nozzle vanes are arranged at equal pitches in the circumferential direction on the side and are mounted so as to be rotatable around a pivot, and the driving fluid flows into the turbine wheel from the scroll passage between the nozzle vanes and the adjacent nozzle vanes. In a variable capacity turbocharger forming a nozzle throat, the nozzle vane includes: The position of the pivot in the nozzle vane, the moment around the pivot acting on the nozzle vane by the static pressure of the drive fluid when the driving fluid is introduced into the scroll passage, the front edge of the nozzle vane toward the scroll passage side Set to a position that works in the direction of rotation A variable-capacity turbocharger is provided.
[0034]
No. 1 According to the variable capacity turbocharger of the means of , Even if the distance from the trailing edge of the bot is smaller than before, the direction of the moment due to the static pressure of the driving fluid can be prevented from being switched, in which case the control position and control characteristics in the rotation control of the nozzle vane are stabilized, and Should the drive system such as the actuator of the variable nozzle mechanism fail, the nozzle flow path is closed and the function of the variable capacity turbocharger does not stop, and the trailing edge of the nozzle vane moves. And the fluid characteristics of the flow of the driving fluid with the turbine wheel can be preferably maintained.
[0035]
( 2 ) 2 As means of 1 In the variable capacity turbocharger according to the above means, the position of the pivot is set so that a distance from a trailing edge of the nozzle vane is in a range of 50% to 75% of a total length of an airfoil cross section of the nozzle vane. I will provide a.
[0036]
No. 2 According to the variable capacity turbocharger of the means of 1 In addition to the operation of the means, a moment in the opening direction can always be stably applied to the nozzle vane, so that the operability and controllability of the nozzle vane are improved, and the accuracy of nozzle control of the variable displacement turbocharger is improved.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
A variable capacity turbocharger according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a nozzle vane provided in the variable capacity turbocharger according to the present embodiment. The variable-capacity turbocharger according to the present embodiment has a nozzle vane having a cross-sectional shape different from that of the conventional variable-capacity turbocharger nozzle vane described with reference to FIGS. 6 to 10. As a result, the pivot position of the nozzle vane is shifted. The other components are configured in the same manner. In the present embodiment, the same components as those shown in FIGS. 6 to 10 are omitted from the drawings and the description is omitted, and different points are mainly described.
[0038]
Accordingly, regarding the same points as above, FIGS. 6 to 10 are referred to by the same names and the same reference numerals in the description of the present embodiment.
[0039]
This is the same in other embodiments described later.
[0040]
As shown in FIG. 1, the nozzle vane 101 of the variable displacement turbocharger according to the present embodiment is configured such that a region extending over a distance from the front edge 101 a to a rear L1 from the front edge 101 a in the cross section is provided on the front edge 101 a side of the suction surface 101 n. The mechanically designed nozzle vane 1 has a modified shape portion 101c in which the maximum T1 depth is cut to reduce the blade thickness to the pre-change shape 1c of the cross section of the nozzle vane 1. This enlarges the nozzle throat 5a facing the modified shape portion 101c. Note that 101p is a pressure surface, and 101b is a trailing edge.
[0041]
The length L1 of the modified shape portion 101c varies depending on the overlapping length Lo of the leading edge and the trailing edge. However, from the possible range of the overlapping length Lo, the length L1 of the nozzle vane 101 is set to L1１0.1 ０．３0.3 L. The cutting depth T1 is about T1Ｔ0.1 to 0.5T with respect to the blade thickness T.
[0042]
In the variable capacity turbocharger according to the present embodiment as described above, the nozzle throat 5a facing the changed shape portion 101c on the front edge 101a side of the negative pressure surface 101n of the nozzle vane 101 is different from the case of the conventional shape 1c before change. Is increased, the flow velocity of the exhaust gas g in the nozzle throat 5a becomes slow, and the static pressure p1 rises by the decrease in the flow velocity.
[0043]
Therefore, the force for pushing up the leading edge 101a increases, and the generated positive moment ΔM reduces the closing moment M (−) acting on the leading edge 101a side, and the total moment M around the pivot 3 of the nozzle vane 101. Moves in the positive direction, the position of the pivot 3 at which the moment M becomes positive can be closer to the trailing edge 101b side, the operability and controllability of the nozzle vane 101 are good, and the exhaust from the nozzle vane 101 to the turbine wheel 36 is improved. A variable capacity turbocharger having good flow characteristics of the flow of the gas g is obtained.
[0044]
Referring to FIG. 2, a variable capacity turbocharger according to a second embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of a main part of a nozzle vane provided in the variable capacity turbocharger according to the present embodiment.
[0045]
As shown in FIG. 2, the nozzle vane 201 of the variable-capacity turbocharger according to the present embodiment is configured such that a region extending over a distance from the rear edge 201b to the front L2 in the cross section on the rear edge 201b side of the pressure surface 201p is a conventional fluid The mechanically designed nozzle vane 1 has a modified shape portion 201c in which a maximum T2 depth is cut to reduce the blade thickness with respect to the pre-change shape 1c of the cross section of the nozzle vane 1. This enlarges the nozzle throat 5b facing the modified shape portion 201c. In addition, 201n is a negative pressure surface. The leading edge and the pivot are the same as in FIG.
[0046]
The length L2 of the modified shape portion 201c differs depending on the overlapping length Lo of the leading edge and the trailing edge, but the trailing edge 201b side has a smaller blade thickness, and the length L2 of the nozzle vane 201 is smaller than the length L2. L2 ≒ 0.05 to 0.15 L.
[0047]
Further, the cutting depth T2 is about 0.1 to 0.5 T with respect to the blade thickness T.
[0048]
In the variable capacity turbocharger according to the present embodiment as described above, the nozzle throat 5b facing the changed shape portion 201c on the trailing edge 201b side of the pressure surface 201p of the nozzle vane 201 is different from the conventional shape 1c before change. Is increased, the flow velocity of the exhaust gas g in the nozzle throat 5b is reduced, and the static pressure p2 is increased by the reduced flow velocity.
[0049]
Therefore, the force for pushing down the trailing edge 201b increases, and the generated positive moment ΔM increases the moment M (+) in the opening direction acting on the trailing edge 201b side, and the total moment of the nozzle vane 201 around the pivot 3 Since M shifts in the positive direction, the position of the pivot 3 at which the moment M becomes positive can be closer to the trailing edge 201b side, the operability and controllability of the nozzle vane 201 are good, and the movement of the nozzle vane 201 to the turbine wheel 36 is improved. A variable capacity turbocharger having good flow characteristics of the flow of the exhaust gas g is obtained.
[0050]
A variable capacity turbocharger according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of a nozzle vane provided in the variable displacement turbocharger according to the present embodiment.
[0051]
As shown in FIG. 3, the nozzle vane 301 of the variable-capacity turbocharger according to the present embodiment is configured such that a region extending over the distance from the front edge 301a to the rear L3 in the cross section on the front edge 301a side of the pressure surface 301p is a conventional fluid. The nozzle vane 1 of the mechanical design has a modified shape portion 301c in which a maximum T3 depth is cut and the blade thickness is reduced so as to bend and form a surface connected to the front and rear surfaces with respect to the shape 1c before the cross section of the nozzle vane 1 is changed. It is assumed. As a result, the nozzle throat 5c facing the modified shape portion 301c is discontinuously and rapidly enlarged. Note that 301n is a negative pressure surface, and 301b is a trailing edge.
[0052]
The length L3 of the modified shape portion 301c is determined by the overlapping length Lo of the leading edge and the trailing edge described above and the separation behavior of the effective flow of the exhaust gas g at the nozzle throat 5c facing the modified shape portion 301c described later. Is L3 ≒ 0.1-0.3 L with respect to the total length L of the nozzle vane 301.
[0053]
The cutting depth T3 is about T3Ｔ0.1 to 0.5T with respect to the blade thickness T.
[0054]
In the variable capacity turbocharger of the present embodiment as described above, the nozzle throat 5c facing the changed shape portion 301c on the front edge 301a side of the pressure surface 301p of the nozzle vane 301 is different from the case of the conventional shape 1c before change. When the flow rate of the exhaust gas g is high, the inertia of the fluid is high, and when the flow is turned by the rapid flow path expansion, separation occurs, and the static pressure of the nozzle throat 5c is increased. p3 will decrease.
[0055]
According to an example of the analysis result, the static pressure drop due to the separation is that when the exhaust gas g has a large flow rate (nozzle vane opening is large), the separation causes the nozzle throat 5 outlet to reach a distance of 0.345 L from the leading edge 301a. A static pressure of 130 kPa, the same as the static pressure of the part, was formed. Therefore, the length L3 of the modified shape portion 301c is set to about L3３0.1 to 0.3 L with respect to the entire length L of the nozzle vane 301 in consideration of the effective static pressure drop region due to peeling.
[0056]
For this reason, the force for pushing up the leading edge 301a increases, and the generated positive moment ΔM decreases the closing moment M (−) acting on the leading edge 301a side, and the total moment of the nozzle vane 301 around the pivot 3 M moves in the forward direction.
[0057]
Referring to FIG. 4, a variable capacity turbocharger according to a fourth embodiment of the present invention will be described. FIG. 4 is a cross-sectional view of a main part of a nozzle vane provided in the variable capacity turbocharger according to the present embodiment.
[0058]
As shown in FIG. 4, the nozzle vane 401 of the variable displacement turbocharger according to the present embodiment is configured such that a region extending over the distance from the rear edge 401 b to the front L4 in the cross section is located on the rear edge 401 b side of the suction surface 401 n in the conventional fluid. The nozzle vane 1 having the mechanical design has a modified shape portion 401c in which a maximum T4 depth is cut and a blade thickness is reduced so as to bend and form a surface connected to the front and rear surfaces with respect to the shape 1c before the cross section of the nozzle vane 1 is changed. It is assumed. As a result, the nozzle throat 5d facing the modified shape portion 401c is discontinuously and rapidly enlarged. In addition, 401p is a pressure surface. The leading edge and the pivot are the same as in FIG. 3 and are not shown.
[0059]
The length L4 of the modified shape portion 401c depends on the overlapping length Lo of the leading edge and the trailing edge, and the separation behavior of the effective flow of the exhaust gas g at the nozzle throat 5d facing the similar modified shape portion 401c. However, in consideration of the thin blade thickness on the trailing edge 401b side, L4 is about 0.05 to 0.15L with respect to the total length L of the nozzle vane 401. Further, the cutting depth T4 is about 0.1 to 0.5 T with respect to the blade thickness T.
[0060]
In the variable capacity turbocharger according to the present embodiment as described above, the nozzle throat 5d facing the changed shape portion 401c on the trailing edge 401b side of the negative pressure surface 401n of the nozzle vane 401 is different from the case of the conventional shape 1c before change. When the flow rate of the exhaust gas g is high, the inertia of the fluid is high. When the flow is turned by the rapid flow expansion, separation occurs, and the static pressure of the nozzle throat 5d is increased. p4 will decrease.
[0061]
Therefore, the force for pushing down the trailing edge 401b increases, and the generated positive moment ΔM increases the moment M (+) in the opening direction acting on the trailing edge 401b side, and the total moment of the nozzle vane 401 around the pivot 3 M moves in the forward direction.
[0062]
As described above, in any of the first to fourth embodiments, since the total moment M of the nozzle vanes 101 to 401 around the pivot 3 shifts in the positive direction, the same pivot as shown in FIG. The moments M at the positions P1 to P5 of No. 3 shift in the positive direction.
[0063]
FIG. 5 is an explanatory view of the moment around the pivot acting on the nozzle vane as shown in FIG. 10 (a). The black square points indicate the nozzle vane 1 of the conventional hydrodynamic design, and the white square points indicate the head. The analysis result in the case of the nozzle vane 101 of the first embodiment of the present invention is shown. Note that the same result is obtained in any of the second to fourth embodiments.
[0064]
As shown in FIG. 5, since the total moment M around the pivot 3 in the first embodiment shifts by ΔM in the positive direction, the position of the pivot 3 at which the moment M becomes 0 (the moment in the opening direction and the moment in the closing direction are balanced) On the leading edge 101a side from that position, a positive (opening) moment M is applied to the nozzle vane 101) from the position of P01 near the conventional P4 in the figure between P3 and P2 in the figure. Move to the position of P02.
[0065]
Therefore, in the variable capacity turbocharger according to the first embodiment, the moment M becomes positive (opening direction), and the trailing edge 101b of the pivot 3 acts on the leading edge 101a of the nozzle vane 101 in the direction in which the scroll passage 40 rotates. Can be set to 0.5 L or less, and if the pivot 3 is positioned in the range of Lp = 0.5 to 0.75 L, the nozzle vane 101 is always stably provided with a moment in the opening direction. In the event that a failure occurs in the drive system such as the actuator of the variable nozzle mechanism 4, the accident that the nozzle flow path is closed and the function of the variable capacity turbocharger is stopped can be avoided, and the nozzle vane can be prevented. Operability and controllability can be improved, and the accuracy of nozzle control of the variable capacity turbocharger can be improved.
[0066]
Further, even in a case where a state in which a moment in the opening direction is always applied to the nozzle vane 101 is obtained, the pivot 3 is farther away from the trailing edge 101b than in the nozzle vane 1 of the conventional hydrodynamic design, for example, Lp = 0. 5 (P3). As a result, the fluid characteristics of the flow of the exhaust gas g from the nozzle vanes 101 to the turbine wheel 36 can be maintained well, and the efficiency of the variable displacement turbocharger can be maintained high.
[0067]
Although the first embodiment has been described as an example, the above is the same in any of the second to fourth embodiments.
[0068]
As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and it goes without saying that various changes may be made to the specific structure within the scope of the present invention. Nor.
[0069]
For example, both the conventional example and the embodiment have been described by showing the center line 8 of the airfoil of the nozzle vane as a curved back vane, but the same applies to the case where the centerline of the airfoil (not shown) is a straight straight vane. Action and effect can be obtained.
[0070]
【The invention's effect】
(1) According to the first aspect of the present invention, the variable-capacity turbocharger is disposed at a constant pitch in the circumferential direction on the inner circumferential side of the scroll passage in which the driving fluid is introduced surrounding the turbine wheel, A variable-capacity turbocharger comprising a plurality of nozzle vanes rotatably controlled around a pivot, the nozzle vane forming a nozzle throat between the adjacent nozzle vanes and a nozzle passage through which the driving fluid flows from the scroll passage to the turbine wheel. , The nozzle vane The position of the pivot in the nozzle vane, the moment around the pivot acting on the nozzle vane by the static pressure of the drive fluid when the driving fluid is introduced into the scroll passage, the front edge of the nozzle vane toward the scroll passage side Since it is configured to be set to a position that acts in the direction of rotation, even if the distance from the trailing edge of the pivot is smaller than in the past, the direction of the moment due to the static pressure of the driving fluid can be prevented from being switched. In this case, the control position and control characteristics in the rotation control of the nozzle vanes are made constant, and the accuracy of the nozzle control of the variable displacement turbocharger is improved. Also, in the unlikely event that a drive system such as an actuator of the variable nozzle mechanism fails, the nozzle flow path is closed and the function of the variable capacity turbocharger stops functioning, and the trailing edge of the nozzle vane is eliminated. If the moving distance can be reduced, the fluid characteristics of the flow of the driving fluid with the turbine wheel can be preferably maintained, and the efficiency of the variable capacity turbocharger can be maintained high. .
[0075]
( 2 ) Claims 2 According to the invention of claim 1 In the variable displacement turbocharger described in the above, the position of the pivot is set so that the distance from the trailing edge of the nozzle vane is in the range of 50% to 75% of the total length of the airfoil section of the nozzle vane. 1 In addition to the effects of the invention described above, a moment in the opening direction can always be stably applied to the nozzle vane, the operability and controllability of the nozzle vane are improved, and a variable displacement turbocharger with high nozzle control accuracy is obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a nozzle vane provided in a variable capacity turbocharger according to a first embodiment of the present invention.
FIG. 2 is a sectional view of a main part of a nozzle vane provided in a variable capacity turbocharger according to a second embodiment of the present invention.
FIG. 3 is a sectional view of a nozzle vane provided in a variable capacity turbocharger according to a third embodiment of the present invention.
FIG. 4 is a sectional view of a main part of a nozzle vane provided in a variable capacity turbocharger according to a fourth embodiment of the present invention.
FIG. 5 is an explanatory view of a moment around a pivot acting on a nozzle vane, similar to that shown in FIG. 10 (b).
FIG. 6 is a longitudinal sectional view of a general variable capacity turbocharger.
FIG. 7 is an operation explanatory view of the nozzle vane as viewed from the direction of arrows AA in FIG. 6;
FIG. 8 is an explanatory diagram of a pressure action in a nozzle vane showing the same surface as FIG. 7;
9A and 9B are cross-sectional explanatory views of a conventional nozzle vane showing the same surface as FIG. 7, wherein FIG. 9A is a state in which the nozzle vane is closed, and FIG. 9B is an enlarged view of the cross-sectional shape of the nozzle vane.
10A is an explanatory diagram of a position of a pivot in a nozzle vane, and FIG. 10B is an explanatory diagram of a moment around the pivot acting on a nozzle vane of a conventional hydrodynamic design.
[Explanation of symbols]
1 nozzle vane
1c Shape before change
2 Nozzle mount
3 pivot
4 Variable nozzle mechanism
5 Nozzle throat
5a, 5b, 5c, 5d Nozzle throat
6 pivot pitch circle
30 Variable capacity turbocharger
33 Turbine rotor
36 Turbine wheel
37 Turbine casing
38 Exhaust gas inlet
39 Exhaust gas outlet
40 scroll passage
41 axis of rotation
101, 201, 301, 401 Nozzle vane
101a, 301a Leading edge
101b, 201b, 301b, 401b Trailing edge
101c, 201c, 301c, 401c Modified shape part
101p, 201p, 301p, 401p Pressure surface
101n, 201n, 301n, 401n Suction surface

Claims (2)

A scroll passage surrounding the turbine wheel, into which a drive fluid is introduced, and a plurality of nozzle vanes disposed at an equal pitch in a circumferential direction on an inner peripheral side of the scroll passage and attached so as to be rotatable around a pivot. In a variable capacity turbocharger in which a nozzle vane forms a nozzle throat through which a driving fluid flows from the scroll passage to the turbine wheel between adjacent nozzle vanes, the nozzle vane has a pivot position in the nozzle vane, and the driving fluid has The moment around the pivot acting on the nozzle vane due to the static pressure of the driving fluid when introduced into the scroll passage is set to a position acting in a direction for rotating the front edge of the nozzle vane toward the scroll passage. Variable capacity turbocharger characterized by the following. In the variable geometry turbocharger according to claim 1, the position of the pivot, and wherein the distance from the rear edge of the nozzle vane is in the range of 50% of the total length of the airfoil cross section of the nozzle vane 75% variable capacity turbocharger to be.

Images