JP2017002910A - Turbine and vehicular supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sufficiently a turbine efficiency not only in the case that a working point of a turbine 29 is set in a high rotation region but also in the case that the working point of the turbine is set in a low rotation region.SOLUTION: A swirl turbine scroll flow passage 41 capable of taking in discharged gas is formed at an inlet side of a turbine impeller 33 inside a turbine housing 31, a gas discharging port 43 for discharging the discharged gas is formed at an outlet side of the turbine impeller 33 at the turbine housing 31, and an orifice part 45 of which inner diameter is gradually reduced toward a downstream direction is formed just downstream side of the turbine impeller 33 at a shroud 31s of the turbine housing 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a turbine that generates a rotational force using pressure energy of a gas such as exhaust gas.

  Conventionally, various developments have been made on turbines used in vehicle superchargers. A typical turbine configuration will be described with reference to FIG. Here, FIG. 4 is a side sectional view showing a general turbine. In the drawings, “FF” indicates the forward direction, and “FR” indicates the backward direction.

  As shown in FIG. 4, a general turbine 101 includes a turbine housing 103, and the turbine housing 103 has a shroud (inner wall) 103 s inside. A turbine impeller 105 is rotatably provided in the turbine housing 103. The turbine impeller 105 is configured to rotate around an axis (an axis of the turbine impeller 105) SC and a turbine wheel 107. A plurality of turbine blades 109 (only one is shown) are provided on the outer peripheral surface 107h at intervals. Here, the outer peripheral surface 107 h of the turbine wheel 107 extends radially outward from the axial direction of the turbine impeller 105 (in other words, the axial direction of the turbine wheel 107), and the tip edge (outer edge) 109 t of each turbine blade 109. Extends along the shroud 103 s of the turbine housing 103.

  On the inlet side of the turbine impeller 105 inside the turbine housing 103, a spiral (annular) turbine scroll passage 111 capable of taking in exhaust gas (an example of gas) is formed. The exhaust gas can be taken in. Further, a gas discharge port 113 for discharging exhaust gas is formed on the outlet side of the turbine impeller 105 in the turbine housing 103.

  In addition, there exists a thing shown to patent document 1 as a prior art relevant to this invention.

JP 09-264106 A

  By the way, when a three-dimensional steady viscosity CFD (Computational Fluid Dynamics) analysis is performed on a gas flow line (stream line distribution) from the inlet side to the outlet side of the turbine impeller 105 during operation of the turbine 101, FIG. As shown in FIG. 4B and FIG. 4, when the operating point (operating state) of the turbine 101 is in a high rotation range (high rotation state), a reverse flow region (back flow) from the inlet side to the outlet side of the turbine impeller 105. However, when the operating point of the turbine 101 is in a low rotation range (low rotation state), a backflow region may be generated near the shroud 103s of the turbine housing 103 from the middle of the turbine impeller 105 to the outlet side. found. This is considered to be because the centrifugal force due to the rotation of the turbine impeller 105 is smaller than the centrifugal force due to the curvature (meridional curvature) of the shroud 103 s of the turbine housing 103. Moreover, if the backflow area | region from the middle of the turbine impeller 105 to an exit side increases, the turbine efficiency of the turbine 101 will fall. Here, FIG. 5A is a diagram showing an analysis result of gas flow lines from the inlet side to the outlet side of the turbine impeller when the operating point of a general turbine is in a high rotation region, and FIG. (A) is a figure which shows the analysis result of the streamline of the gas from the inlet side of a turbine impeller to the outlet side in case the operating point of a general turbine exists in a low rotation area.

  On the other hand, in recent years, vehicles having a so-called idling stop function in consideration of environmental conservation and fuel efficiency have become widespread, and accordingly, it has become an urgent task to improve turbine efficiency in a low rotation range after engine start. Yes.

  Accordingly, an object of the present invention is to provide a turbine or the like having a novel configuration that can improve turbine efficiency not only when the operating point is in the high rotation range but also in the low rotation range.

  As a result of repeating trial and error in order to solve the above-described problems, the inventor of the present invention has reduced the inner diameter gradually toward the downstream side of the turbine impeller in the shroud of the turbine housing. By forming the phantom line portion in FIG. 4, as shown in FIGS. 6 (a) and 6 (b), when the operating point is in the high rotation range, the reverse flow region is formed from the inlet side to the outlet side of the turbine impeller. When the operating point is in the low rotation range after being prevented from being generated, it is in the middle of the turbine impeller compared to a general turbine (see FIGS. 4 and 5B) that does not have a throttle portion. The present inventors have been able to obtain a new finding that the backflow region generated from the outlet to the outlet side can be sufficiently reduced, thereby completing the present invention. Here, FIG. 6A is an analysis of gas flow lines from the inlet side to the outlet side of the turbine impeller when the operating point of the turbine according to the invention (turbine having a throttle portion) is in a high rotation range. FIG. 6B is a diagram showing the results (results of three-dimensional steady viscosity CFD), and FIG. 6B shows the gas flow from the inlet side to the outlet side of the turbine impeller when the operating point of the turbine according to the example of the invention is in the low rotation range. It is a figure which shows the analysis result (result of three-dimensional steady viscosity CFD) of a line.

  Note that, in the turbine according to the invention example that is the object of the three-dimensional steady viscosity CFD, an expansion portion whose inner diameter is gradually increased in the downstream direction is formed immediately downstream of the throttle portion in the shroud of the turbine housing. It is.

According to a first aspect of the present invention, there is provided a turbine for generating a rotational force using pressure energy of a gas, a turbine housing having a shroud (inner wall) on the inner side, a turbine housing rotatably provided in the turbine housing, And a turbine wheel having a plurality of turbine blades provided at intervals on the outer circumferential surface of the turbine wheel, and a turbine wheel having an outer circumferential surface extending radially outward from the axial direction. In addition, a spiral turbine scroll passage capable of taking in gas is formed on the inlet side (upstream side) of the turbine impeller inside the turbine housing, and on the outlet side (downstream side) of the turbine impeller in the turbine housing. A gas outlet for discharging gas is formed and the shroud of the turbine housing A throttle portion having an inner diameter gradually reduced in the downstream direction is formed immediately downstream (immediately downstream) of the turbine impeller in the downstream of the throttle portion with respect to the rotational radius of the tip end of the trailing edge of the turbine blade. The ratio of the inner radius of the end is set to 0.90 to 0.95, and the turbine blade leading edge hub to the axial length from the turbine blade leading edge hub end to the trailing edge tip end The ratio of the length in the axial direction from the end to the downstream end of the throttle portion is set to 1.20 to 1.35.
A second aspect of the present invention includes a turbine housing including a shroud, and a turbine impeller provided in the turbine housing and having turbine blades, and the turbine housing has a downstream side of the turbine impeller in the shroud. A throttle portion having an inner diameter gradually reduced in the downstream direction is provided, and the ratio of the inner radius of the downstream end of the throttle portion to the radius of rotation of the tip end of the trailing edge of the turbine blade is 0.90-0. .95, and the axial length from the hub end of the turbine blade leading edge to the downstream end of the throttle relative to the axial length from the hub edge of the leading edge of the turbine blade to the tip end of the trailing edge The ratio is 1.20 to 1.35.
A third aspect of the present invention includes a turbine housing including a shroud, and a turbine impeller provided in the turbine housing, and the turbine housing has a downstream side downstream of the turbine impeller in the shroud. A throttle part with a gradually reduced inner diameter is provided, and an expansion part with a gradually increased inner diameter is provided immediately downstream of the throttle part.

  In the specification and claims of the present application, “upstream” means upstream when viewed from the mainstream flow direction, and “downstream” means downstream when viewed from the mainstream flow direction. .

  According to the configuration of the present invention, the gas taken into the turbine scroll passage is circulated from the inlet side to the outlet side of the turbine impeller. Thereby, a rotational force (rotational torque) can be generated using the pressure energy of the gas.

  And since the said throttle part which reduced the internal diameter gradually toward the downstream direction is formed in the immediately downstream side of the said turbine impeller in the said shroud of the said turbine housing, when the above-mentioned novel knowledge is applied, the said turbine When the operating point of the turbine is in the low rotation range, the counter flow region is not generated from the inlet side to the outlet side of the turbine impeller. Compared with a general turbine that does not have a section, the backflow region generated from the middle of the turbine impeller to the outlet side can be sufficiently reduced.

  The fourth aspect of the present invention includes a turbine having any one of the first to third aspects of the present invention.

  According to the configuration of the fourth aspect of the present invention, the same effect as the effect of any one of the configurations of the first to third aspects of the present invention is achieved.

  According to the present invention, when the operating point of the turbine is in a high rotation region, a backflow region is not generated from the inlet side to the outlet side of the turbine impeller, and then the operating point of the turbine is set in a low rotation region. In this case, since the backflow region generated from the middle of the turbine impeller to the outlet side can be sufficiently reduced, not only when the operating point of the turbine is in the high rotation region but also in the low rotation region In addition, the turbine efficiency of the turbine can be sufficiently improved.

FIG. 1 is a side sectional view showing a turbine according to an embodiment of the present invention. FIG. 2 is a side cross-sectional view of the vehicle supercharger according to the embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the turbine rotational speed and the turbine efficiency in the turbine according to the invention example and the comparative example. FIG. 4 is a side cross-sectional view showing a general turbine, and also shows the characteristics of the turbine according to the invention example in phantom lines. FIG. 5 (a) is a diagram showing the analysis result of gas flow lines from the inlet side to the outlet side of the turbine impeller when the operating point of a general turbine is in a high rotation range, and FIG. It is a figure which shows the analysis result of the streamline of the gas from the entrance side of a turbine impeller in the case of the operating point of a general turbine in a low rotation area to the exit side. FIG. 6A is a diagram showing an analysis result of gas flow lines from the inlet side to the outlet side of the turbine impeller when the operating point of the turbine according to the invention is in a high rotation range, and FIG. FIG. 5 is a diagram showing an analysis result of gas flow lines from the inlet side to the outlet side of the turbine impeller when the operating point of the turbine according to the invention example is in a low rotation range.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the drawings, “FF” indicates the forward direction, and “FR” indicates the backward direction.

  As shown in FIG. 2, the vehicle supercharger 1 according to the embodiment of the present invention uses the energy of exhaust gas (an example of gas) from an engine (not shown) to supply air supplied to the engine. Supercharge (compress). And the specific structure of the supercharger 1 for vehicles is as follows.

  The vehicle supercharger 1 includes a bearing housing 3, and a pair of radial bearings 5 and a pair of thrust bearings 7 are provided in the bearing housing 3. Further, the plurality of bearings 5 and 7 are provided with a rotor shaft (turbine shaft) 9 extending in the front-rear direction so as to be rotatable. In other words, the rotor shaft 9 is provided in the bearing housing 3 with the plurality of bearings 5. , 7 are rotatably provided.

  A compressor 11 that compresses air using centrifugal force is disposed on the front side of the bearing housing 3, and the specific configuration of the compressor 11 is as follows.

  A compressor housing 13 is provided on the front side of the bearing housing 3, and a compressor impeller 15 is rotatably provided in the compressor housing 13. The components of the compressor impeller 15 will be described. A compressor wheel 17 is provided in the compressor housing 13. The compressor wheel 17 is connected to the front end of the rotor shaft 9. (In other words, the axis of the rotor shaft 9) SC. A plurality of compressor blades 19 are provided on the outer peripheral surface 17 h of the compressor wheel 17 at intervals in the circumferential direction.

  An air intake 21 for taking in air is formed on the inlet side of the compressor impeller 15 in the compressor housing 13 (the front side of the compressor housing 13). This air intake 21 is an air cleaner (not shown) for purifying air. ) Can be connected. An annular diffuser flow path 23 that pressurizes the compressed air is formed on the outlet side of the compressor impeller 15 between the bearing housing 3 and the compressor housing 13. It communicates with the inlet 21. Further, a compressor scroll passage 25 is formed inside the compressor housing 13 so as to surround the compressor impeller 15, and the compressor scroll passage 25 communicates with the diffuser passage 23. An air discharge port 27 for discharging the compressed air is formed at an appropriate position of the compressor housing 13, and this air discharge port 27 communicates with the compressor scroll flow path 25 to supply the engine. It can be connected to an air manifold (not shown).

  A turbine 29 that generates rotational force (rotational torque) using the pressure energy of the exhaust gas is disposed on the rear side of the bearing housing 3. The specific configuration of the turbine 29 is as follows. Become.

  As shown in FIGS. 1 and 2, a turbine housing 31 is provided on the rear side of the bearing housing 3, and the turbine housing 31 has a shroud 31 s on the inner side. The turbine impeller 33 is rotatably provided. The components of the turbine impeller 33 will be described. A turbine wheel 35 is provided in the turbine housing 31, and the turbine wheel 35 is integrally connected to the rear end portion of the rotor shaft 9. The turbine impeller 33 is rotatable about the axis SC (in other words, the axis of the rotor shaft 9) SC. Further, the outer peripheral surface 35 h of the turbine wheel 35 extends radially outward from the axial direction of the turbine impeller 33. Further, a plurality of turbine blades 37 are provided on the outer peripheral surface 35 h of the turbine wheel 35 at intervals in the circumferential direction, and a tip edge (outer edge) 37 t of each turbine blade 37 is a shroud 31 s of the turbine housing 31. It extends so that.

  A gas intake port 39 for taking in exhaust gas is formed at an appropriate position of the turbine housing 31, and this gas intake port 39 can be connected to an exhaust manifold (not shown) of the engine. Further, a spiral (annular) turbine scroll passage 41 is formed on the inlet side of the turbine impeller 33 inside the turbine housing 31, and the turbine scroll passage 41 communicates with the gas inlet 39. Therefore, exhaust gas can be taken in. Further, a gas discharge port 43 for discharging exhaust gas is formed at the outlet side of the turbine impeller 33 in the turbine housing 31 (the rear side of the turbine housing 31). The gas discharge port 43 is connected to the turbine scroll passage 41. And can be connected to an exhaust gas purification device (not shown) via a connecting pipe (not shown).

  In the shroud 31 s of the turbine housing 31, a throttle portion 45 having an inner diameter gradually reduced in the downstream direction is formed immediately downstream (immediately after the downstream side) of the turbine impeller 33. In addition, an expansion portion 47 having an inner diameter that gradually increases in the downstream direction is formed continuously on the downstream side of the throttle portion 45 in the shroud 31 s of the turbine housing 31.

  Here, the ratio (R2 / R1) of the inner radius R2 of the downstream end of the throttle portion 45 to the rotation radius R1 of the tip end of the trailing edge 37p of the turbine blade 37 is set to 0.90 to 0.95. Further, the axial length from the hub end of the front edge 37f of the turbine blade 37 to the downstream end of the throttle portion 45 with respect to the axial length L1 from the hub end of the front edge 37f of the turbine blade 37 to the tip end of the rear edge 37p. The ratio of the length L2 (L2 / L1) is set to 1.20 to 1.35. Here, the ratio (R2 / R1) is set to 0.90 or more and the ratio (L2 / L1) is set to 1.35 or less because the ratio (R2 / R1) is less than 0.90. If the ratio (L2 / L1) is set to exceed 1.35, the effect of reducing the backflow region when the operating point of the turbine 29 described later is in the low rotation range is not sufficiently exhibited. . On the other hand, when the ratio (R2 / R1) is set to 0.95 or less and the ratio (L2 / L1) is set to 1.20 or more, the ratio (L2 / L1) exceeds 1.35. If the ratio is set or the ratio (L2 / L1) is set to less than 1.20, the throttle ratio of the throttle unit 45 increases, and a new backflow region is generated when the operating point is outside the low rotation range. This is because there is a concern about this.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  By causing the exhaust gas taken in from the gas intake port 39 to flow from the inlet side to the outlet side of the turbine impeller 33 via the turbine scroll flow path 41, a rotational force (rotational torque) is generated using the pressure energy of the exhaust gas. Thus, the rotor shaft 9 and the compressor impeller 15 can be rotated integrally with the turbine impeller 33. Thereby, the air taken in from the air intake 21 can be compressed and discharged from the air outlet 27 via the diffuser passage 23 and the compressor scroll passage 25, and the air supplied to the engine is supercharged. can do.

  Since the throttle portion 45 having an inner diameter gradually reduced in the downstream direction is formed immediately downstream of the turbine impeller 33 in the shroud 31 s of the turbine housing 31, the operation of the turbine 29 is performed by applying the above-described new knowledge. When the point is in the high rotation range, the counter flow region is not generated from the inlet side to the outlet side of the turbine impeller 33, and when the operating point of the turbine 29 is in the low rotation range, the throttle unit 45 is Compared to a general turbine 101 that does not have (see FIG. 4), the backflow region generated from the middle of the turbine impeller 33 to the outlet side can be sufficiently reduced.

  Therefore, according to the embodiment of the present invention, the turbine efficiency of the turbine 29 can be sufficiently improved not only when the operating point of the turbine 29 is in the high rotation range but also in the low rotation range.

  Specifically, the turbine 29 according to the embodiment of the present invention is the turbine according to the invention example, and the general turbine 101 (see FIG. 4) that does not have the throttle portion 45 is the turbine according to the comparative example. A three-dimensional steady viscosity CFD analysis is performed on the turbine rotation speed and turbine efficiency of the turbine according to the comparative example, and the results are summarized as shown in FIG. That is, as shown in FIG. 3, the turbine efficiency of the turbine according to the invention example was sufficiently improved over the wide operation range from the low rotation range to the high rotation range than the turbine efficiency of the turbine according to the comparative example. Was confirmed.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

DESCRIPTION OF SYMBOLS 1 Vehicle supercharger 3 Bearing housing 9 Rotor shaft 11 Compressor 13 Compressor housing 15 Compressor impeller 29 Turbine 31 Turbine housing 31s Turbine housing shroud 33 Turbine impeller 35 Turbine wheel 35h Turbine wheel outer peripheral surface 37 Turbine blade 37f Front of turbine blade Edge 37p Trailing edge 39 of turbine blade Gas inlet 41 Turbine scroll passage 43 Gas outlet 45 Restriction part 47 Expansion part

Claims (2)

A turbine housing including a shroud;
A turbine impeller provided in the turbine housing,
The shroud of the turbine housing is provided with a throttle portion with a gradually reduced inner diameter in the downstream direction immediately downstream of the turbine impeller, and further in the downstream direction immediately downstream of the throttle portion. A turbine provided with an expansion portion having an inner diameter gradually enlarged.   A supercharger for a vehicle comprising the turbine according to claim 1.

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