JP6500448B2 - Turbocharger - Google Patents

Description

  The present invention relates to a turbocharger.

  Conventionally, as a technology in this field, a turbine described in Patent Document 1 below is known. The scroll portion of the turbine includes a large scroll, a middle scroll, and a small scroll arranged in the radial direction of the turbine wheel. There is known a turbine whose capacity is variable by providing a plurality of scrolls arranged radially in this manner.

Patent 3876185 gazette

  However, in the case where the scroll portion is configured by a plurality of scrolls, the flow state of the fluid flowing into the turbine wheel is different from the flow angle when the fluid flows into the turbine wheel because the fluid flow state toward the turbine wheel differs for each scroll through which the fluid passes. Tend to be uneven. As a result, a loss may occur when the fluid flows into the turbine wheel, which may hinder the improvement of the efficiency of the turbine. On the other hand, the present invention aims to improve the efficiency of a turbocharger when the turbine has a plurality of scrolls.

  The turbocharger according to the present invention comprises a turbine having a turbine wheel, a scroll portion provided around the turbine wheel and serving as a flow path for fluid to be fed to the turbine wheel, and the turbine wheel via a rotation shaft. And a compressor having a compressor wheel connected in series, wherein the scroll portion has a plurality of scrolls juxtaposed in the radial direction of the turbine wheel, and for each scroll, the scroll at the winding start position of the scroll The cross-sectional area of the flow path cross section is A, the distance from the axis of rotation of the turbine wheel to the center of the flow path cross is R, and the height of the flow path at the inflow to the turbine wheel from the scroll is b. Sometimes, the value of A / (R · b) is approximately equal in all scrolls.

  The flow angle when fluid flows into the turbine wheel via the scroll depends on A / (R · b). Here, according to the above-described supercharger, since A / (R · b) becomes substantially equal in all the scrolls, all the flow angles of the fluid passing through the scrolls of the scroll portion become substantially equal. Such uniform flow angle reduces the loss that occurs when fluid flows into the turbine wheel, and improves the efficiency of the turbine and the turbocharger.

  Also, the value of A may be substantially equal in all scrolls. In this case, the amount of fluid to be introduced into each scroll can be equalized, for example, it is easy to apply a turbocharger to an internal combustion engine.

  The position in the circumferential direction of the turbine wheel of the winding start position of the scroll may be the same in all the scrolls. In this case, the fluid inlets of the scrolls can be arranged at a close position, and the turbocharger can be made compact.

  According to the present invention, the efficiency of the turbocharger can be improved when the turbine has a plurality of scrolls.

It is a sectional view showing a supercharger concerning an embodiment. It is sectional drawing which shows the scroll part vicinity of the supercharger of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  Hereinafter, an embodiment of a turbocharger according to the present invention will be described with reference to the drawings.

  The supercharger 1 shown in FIG. 1 is applied to, for example, an internal combustion engine of a ship or a vehicle. As shown in FIG. 1, the turbocharger 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 portion 16 that extends circumferentially at the inner peripheral edge. 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 portion 17 extending in the circumferential direction at the inner peripheral edge.

  The turbine wheel 6 is provided at one end of the rotating shaft 14, and the compressor wheel 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 a bearing 15, and the rotating shaft 14, the turbine wheel 6 and the compressor wheel 7 rotate around the rotation axis H as an integral rotating body 12.

  The turbine housing 4 is provided with an exhaust gas inlet 8 and an exhaust gas outlet 10. Exhaust gas (fluid) discharged from an internal combustion engine (not shown) flows into the turbine housing 4 through the exhaust gas inlet 8, flows into the turbine wheel 6 through the scroll portion 16, and rotates the turbine wheel 6. Let Thereafter, the exhaust gas flows out of the turbine housing 4 through the exhaust gas outlet 10.

  The compressor housing 5 is provided with a suction port 9 and a discharge port 11. As described above, when the turbine wheel 6 rotates, the compressor wheel 7 rotates via the rotation shaft 14. The rotating compressor wheel 7 sucks in external air through the suction port 9, compresses it, and discharges it from the discharge port 11 through the scroll portion 17. The compressed air discharged from the discharge port 11 is supplied to the aforementioned internal combustion engine.

  Subsequently, the scroll portion 16 of the turbine 2 will be described in more detail with reference to FIGS. 1 to 4. 2 is a cross-sectional view of the scroll portion 16 taken along a cross section orthogonal to the rotation axis H, FIG. 3 is a III-III cross-sectional view including the rotation axis H, and FIG. It is IV sectional drawing. In the following description, the terms “axial direction”, “radial direction”, and “circumferential direction” mean the axial direction, radial direction, and circumferential direction of the turbine wheel 6, respectively. Moreover, when saying "upstream", "downstream" etc., the upstream and downstream of the exhaust gas in the scroll part 16 shall be meant. In addition, in the case of indicating the position (θ position coordinate) in the circumferential direction of each part centering on the rotation axis H, the right of the rotation axis H in FIG. The lower part is called a 270 degree position.

  The scroll portion 16 is provided around the turbine wheel and constitutes a flow path of exhaust gas to be fed to the turbine wheel 6. The scroll unit 16 has a so-called “double scroll” structure, and includes two scrolls arranged in parallel in the radial direction. Of these two scrolls, one located radially outward is referred to as a first scroll 21 and one located radially inward is referred to as a second scroll 22. The first scroll 21 has an inlet 21a, and the second scroll 22 has an inlet 22a. For example, exhaust gases from different cylinders of the internal combustion engine are introduced into the inlets 21a and 22a, respectively.

  The winding start position 21c of the first scroll 21 and the winding start position 22c of the second scroll 22 are both at 0 degrees. The winding start positions 21c and 22c refer to positions where bending of the shapes of the first scroll 21 and the second scroll 22 starts when viewed in the axial direction (viewed from the direction of FIG. 2).

  The region of the first scroll 21 from the inlet 21 a to the winding start position 21 c extends linearly. On the downstream side of the winding start position 21c, the first scroll 21 is curved by 360 degrees to a 0 degree position while reducing the radius of curvature and the flow path width so as to wind around the turbine wheel 6 . The first scroll 21 is connected to the inflow portion 21 b in a region from the 180 degree position to the 0 degree position. The inflow portion 21 b is a portion where the flow path height (flow path height in the axial direction) is narrowed immediately upstream of the turbine wheel 6 and is 0 degrees from the 180 degree position along the outer peripheral edge of the turbine wheel 6. It extends in a band to the position. The flow path height of the inflow portion 21 b is constant in the circumferential direction from the 180 degree position to the 0 degree position. In addition, the nozzle vane which guides exhaust gas is not provided in the inflow part 21b. After passing through the winding start position 21c, the exhaust gas introduced from the introduction port 21a turns the first scroll 21 180 degrees and further turns 180 degrees and flows into the turbine wheel 6 at a predetermined flow angle through the inflow portion 21b. Do. The “flow angle” refers to the direction of flow when exhaust gas flows into the turbine wheel 6 when viewed in the axial direction (as viewed in the direction of FIG. 2), and the rotation of the turbine wheel 6 at the inflow position. It refers to the angle formed by the direction (the tangential direction of the outer peripheral edge of the turbine wheel 6).

  The area of the second scroll 22 from the inlet 22 a to the winding start position 22 c extends linearly in parallel to the first scroll 21. On the downstream side of the winding start position 22c, the second scroll 22 is positioned 180 degrees while rolling the circumference of the turbine impeller 6 at a position inside the first scroll 21 while reducing the radius of curvature and the flow path width. It is curved and extends up to. The second scroll 22 is connected to the inflow portion 22 b in a region from the 0 degree position to the 180 degree position. The inflow portion 22 b is a portion where the flow path height (flow path height in the axial direction) is narrowed immediately upstream of the turbine wheel 6 and is 180 degrees from the 0 degree position along the outer peripheral edge of the turbine wheel 6. It extends in a band to the position. The flow path height of the inflow portion 22 b is constant in the circumferential direction from the 0 degree position to the 180 degree position. In addition, the nozzle vane which guides exhaust gas is not provided in inflow part 22b. After passing through the winding start position 22c, the exhaust gas introduced from the introduction port 22a flows into the turbine wheel 6 through the inflow portion 22b at a predetermined flow angle while turning the second scroll 22 180 degrees.

  Here, as a parameter for each scroll, the cross-sectional area of the flow path cross section of the scroll at the winding start position is represented by A, and the distance from the rotation axis H of the centroid of the flow path cross section of the scroll at the winding start position is R The height of the flow path at the inflow portion of the exhaust gas from the scroll to the turbine wheel 6 is represented by b. At this time, the scroll unit 16 is designed such that the value of A / (R · b) becomes substantially equal in the first scroll 21 and the second scroll 22.

That is, the above-mentioned parameter relating to the first scroll 21 is suffixed with “1”, and the above parameter relating to the second scroll 22 is suffixed with “2”,
A1: Cross-sectional area of the flow passage cross section of the first scroll 21 at the winding start position 21c R1: Distance from the rotation axis H of the centroid 21d of the flow passage cross section b1: Inflow to the turbine wheel 6 from the first scroll 21 Flow path height A2 in the portion 21b: Cross-sectional area of the flow path cross section of the second scroll 22 at the winding start position 22c R2: Distance from the rotation axis H of the centroid 22d of the flow path cross section b2: From the second scroll 22 If it is set as the flow path height in inflow part 22b to turbine impeller 6,
A1 / (R1 · b1) ≒ A2 / (R2 · b2) (1)
Is established.

  The cross section of the flow passage at the winding start position of the scroll may be connected with the cross section of the inflow portion and not be in a closed shape. In this case, for example, the portion where the flow path height changes discontinuously in the cross section may be defined as the boundary with the cross section of the inflow portion to define the flow path cross section of the scroll. Also, for example, the cross-sectional area A may be defined on the flow passage cross-section at the winding start position, assuming a shape (for example, similar shape) corresponding to the closed flow passage cross-section upstream of the winding start position. . In addition, in the supercharger 1, the flow-path cross section in the winding start position 21c of the 1st scroll 21 has comprised the closed shape. In the second scroll 22, the flow passage cross-section of the downstream side of the winding start position 22c is not a closed shape, but the flow passage cross-section on the upstream side is a closed shape bordering the winding start position 22c There is. Therefore, the closed cross section of the flow path appearing on the boundary can be defined as the flow cross section at the winding start position 22c. In FIG. 3, the boundary between the flow passage cross section at the winding start position 22 c of the second scroll 22 and the cross section of the inflow portion 22 b is indicated by a broken line.

  Also, A1 and A2 may be made substantially equal. That is, A1 ≒ A2 may be further satisfied. If the positions in the circumferential direction of the winding start position 21c and the winding start position 22c are the same, R1> R2, and therefore, if A1 ≒ A2 holds, b1 <b2 from equation (1). That is, as illustrated in FIGS. 3 and 4, the flow channel height b1 of the inflow portion 21b is smaller than the flow channel height b2 of the inflow portion 22b. In this case, a step appears at the boundary between the inflow portion 21 b and the inflow portion 22 b at the 0 ° position and the 180 ° position.

Then, the effect of the supercharger 1 mentioned above is demonstrated. In the turbocharger turbine of this type, the flow velocity of the exhaust gas at the winding start position of the scroll is v0, the radius of the turbine wheel 6 is r, and the circumferential component of the flow velocity v1 of the exhaust gas flowing into the turbine wheel 6 is vu1 If the radial component is vm1 and the compressibility of the exhaust gas is neglected,
From the mass conservation law, v0 · A = vm1 · 2π · r · b,
According to the angular momentum conservation law, v0 · R = vu1 · r.
From these relationships, the flow angle α of the exhaust gas to the turbine wheel is
tan α = vm1 / vu1 = A / (2π · b · R)
Therefore, the flow angle α is determined by A / (R · b).

Here, according to the above-described turbocharger 1,
A1 / (R1 · b1) ≒ A2 / (R2 · b2) (1)
Accordingly, the flow angle α1 of the exhaust gas passing through the first scroll and the flow angle α2 of the exhaust gas passing through the second scroll become substantially equal. If the flow angle α1 and the flow angle α2 are different from each other, a loss occurs because the exhaust gas that collides and mixes immediately before entering the turbine wheel 6 is present. Therefore, by equalizing the flow angle in the circumferential direction, the loss generated when the exhaust gas flows into the turbine impeller 6 is reduced, and the efficiency of the turbine 2 and the turbocharger 1 can be improved.

In equation (1), the left side ≒ the right side instead of the left side 右 辺 right side means that the efficiency improvement of the turbine 2 may be sufficiently improved even if the flow angles α1 and α2 are not completely the same. It is considered that the difference between the flow angles α1 and α2 in such a range is allowed. As a range in which the difference between the flow angles α1 and α2 is allowed, for example, the left side of the equation (1) may be set to a range of 0.85 to 1.15 times the right side. If the left side of Equation (1) is less than 0.85 on the right side or greater than 1.15 on the right side, the difference between the flow angles α1 and α2 becomes large, and the efficiency improvement of the turbine 2 can not be sufficiently achieved. Further, it is more preferable that the left side of the equation (1) is 0.95 to 1.05 times as large as the right side among the above ranges. Also, as a matter of course, in order to achieve the above-mentioned effects more reliably,
A1 / (R1 · b1) = A2 / (R2 · b2) (2)
It may be

  In order to equalize the flow angle in the circumferential direction, it is conceivable to provide a nozzle vane at the inflow portions 21b and 22b, but according to the above-described supercharger 1, it is not necessary to provide a nozzle vane and the number of parts can be reduced. Cost reduction is possible.

  Furthermore, when A1 ≒ A2 holds, the amounts of exhaust gas to be introduced to the first scroll 21 and the second scroll 22 can be made substantially equal. Then, for example, the supercharger 1 can be easily applied to an internal combustion engine such that the same number of cylinders are connected to the first scroll 21 and the second scroll 22, respectively. The reason why A1 ≒ A2 instead of A1 = A2 is considered that the above-mentioned effects can be achieved even if the cross-sectional area A1 and the cross-sectional area A2 are not completely the same. This means that the difference between the cross sectional area A1 and the cross sectional area A2 within the range is allowed. As a matter of course, in order to more reliably achieve the above-described effects, it is possible to set A1 = A2.

  Further, as illustrated in FIG. 2, when the winding start position 21 c of the first scroll 21 and the winding start position 22 c of the second scroll 22 are at the same position in the circumferential direction, the inlet 21 a and the inlet 22a can be arranged at a close position, and the turbocharger 1 can be made compact.

  Although the above describes the turbocharger 1 having two scrolls as an example, all the configurations of the turbocharger 1 described above are generally applicable to a turbine having a plurality of arbitrary numbers of scrolls and a turbocharger. It is obvious that it can be applied in

That is, when the scroll portion has n first to n-th scrolls (n = 2, 3, ...) arranged in parallel in the radial direction of the turbine wheel, according to the configuration of the turbocharger 1, A The value of / (R · b) may be made substantially equal in all the scrolls (first to nth scrolls). In other words,
A1 / (R1 · b1) ≒ A2 / (R2 · b2) ≒ ... ≒ An / (Rn · bn)
Should be established. With this configuration, the flow angles of the exhaust gas passing through the first to n-th scrolls can be made substantially uniform, and the same operation and effect as the aforementioned turbocharger 1 can be achieved. Also,
A1 / (R1 · b1) = A2 / (R2 · b2) =... = An / (Rn · bn)
It may be

  Further, the value of A may be substantially equal in all the scrolls (first to nth scrolls). That is, A1 ≒ A2 ≒ ... ≒ An may be set. Alternatively, A1 = A2 =... = An may be set. In addition, the position in the circumferential direction of the winding start position of the scroll may be the same in all the scrolls (first to nth scrolls). In other words, the winding start positions of all the scrolls (first to nth scrolls) may be in the same plane including the rotation axis H. These configurations also exhibit the same effects as those of the turbocharger 1. The configuration of the turbocharger 1 described above corresponds to the case of n = 2.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, You may deform | transform in the range which does not change the summary described in each claim. You may use combining the structure of each embodiment suitably.

Reference Signs List 1 turbocharger 2 turbine 3 compressor 4 turbine housing 5 compressor housing 6 turbine impeller 7 compressor impeller 8 exhaust gas inlet 9 inlet 10 exhaust gas outlet 11 outlet 12 rotary body 13 bearing housing 14 rotating shaft 15 bearing 16 Scroll part 17 scroll part 21 first scroll 21a inlet 21b inlet 21c winding start position 21d center 22 second scroll 22a inlet 22b inlet 22c winding start position 22d center H rotation axis

Claims (2)

A turbine wheel, wherein provided around the turbine wheel have a, and a scroll portion that forms a fluid flow path is fed to the turbine wheel, the inflow of the fluid to the turbine wheel from the scroll part And a turbine not provided with nozzle vanes for guiding the fluid .
A compressor having a compressor wheel connected to the turbine wheel via a rotation shaft,
The scroll unit includes a plurality of scrolls provided around the turbine wheel and arranged in the radial direction .
For each said scroll,
Let A be the cross-sectional area of the flow passage cross section of the scroll at the winding start position of the scroll,
Let R be the distance from the rotation axis of the turbine wheel, and
The height of the flow path when the b in the inlet to the turbine wheel from the scroll,
The value of A / (R · b) is approximately equal in all the scrolls,
A supercharger, wherein the value of A is approximately equal in all the scrolls.   The turbocharger according to claim 1, wherein a circumferential position of the winding start position of the scroll in the circumferential direction of the turbine wheel is the same in all the scrolls.

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