Patent Grant
11143199
The present disclosure relates to a compressor impeller, a compressor, and a turbocharger.
Conventionally, a compressor and a rotating machine including the compressor have been known. The compressor flows fluid such as air or a gas in a radial direction of a rotating compressor impeller and compresses the fluid by utilizing a centrifugal force generated at this time.
For example, Patent Document 1 and Patent Document 2 each disclose a turbocharger which rotates a turbine impeller by utilizing an exhaust gas and rotates a compressor impeller disposed coaxially with the turbine impeller, thereby increasing a suction pressure of an internal combustion engine.
Patent Document 1: JP2009-209867A
Patent Document 2: U.S. Pat. No. 7,568,883B
Recently, however, demand for downsizing and larger capacity of a compressor is increasing, and thus it is desirable to ensure the capacity of the compressor while suppressing upsizing of the compressor.
Thus, in view of the above, an object of at least some embodiments of the present invention is to provide a compressor impeller, a compressor, and a turbocharger capable of increasing the capacity of the compressor while suppressing upsizing thereof.
(1) A compressor impeller according to some embodiments of the present invention includes an impeller body which includes a boss portion and a plurality of compressor blades disposed on an outer peripheral surface of the boss portion, and a connection portion which is disposed on a side of a back surface of the impeller body and is configured to be connectable to one end of a rotational shaft. A ratio D1/D2 satisfies 0.18 or less, where D1 is a diameter of the boss portion on leading edges of the compressor blades, and D2 is a maximum outer diameter of the compressor blades.
With the above configuration (1), since the connection portion disposed on the side of the back surface of the impeller body is configured to be connectable to the one end of the rotational shaft, it is possible to configure the compressor impeller to be rotatable without providing a through hole for letting through the rotational shaft in the boss portion. Thus, it is possible to decrease the diameter of the boss portion on the leading edges of the compressor blades as compared with the structure of the impeller where the through hole is provided in the boss portion (through-bore structure). As a result, it is possible to increase the flow passage area of fluid guided to the compressor impeller, and thus it is possible to increase the capacity of the compressor while promoting downsizing thereof.
(2) In some embodiments, in the above configuration (1), the connection portion includes a fastening portion configured to fasten and fix the one end of the rotational shaft.
With the above configuration (2), since the connection portion disposed on the side of the back surface of the impeller body includes the fastening portion, it is possible to fix the one end of the rotational shaft to the connection portion by the fastening portion. Thus, it is possible to couple the rotational shaft and the compressor impeller to each other without providing an additional fastening member on the side of the leading edges of the compressor blades. Therefore, it is possible to promote the decrease in the diameter of the boss portion on the side of the leading edges of the compressor blades and to increase the flow passage area, as also described in the above configuration (1).
(3) In some embodiments, in the above configuration (1) or (2), the boss portion has a solid structure at least between the connection portion and the leading edges.
With the above configuration (3), as compared with the through-bore structure in which a centrifugal stress is likely to be generated with concentration in the through hole, it is possible to disperse the centrifugal stress by adopting the solid structure. Accordingly, it is possible to effectively reduce a maximum centrifugal stress, and thus to increase the flow rate and improve durability of the compressor impeller at the same time.
(4) In some embodiments, in any one of the above configurations (1) to (3), the compressor blades include fillet portions in blade root parts thereof, the fillet portions each being disposed on a connection part with the boss portion, and a ratio Σt/L has a maximum value in at least a partial region, where t is blade thicknesses of the compressor blades including the fillet portions in the blade root parts, Σt is a total of the blade thicknesses t of the compressor blades in a circumferential direction, and L is a perimeter of the boss portion, and the maximum value satisfies 0.5 or more.
In order to increase the flow rate, it is desirable to decrease the diameter of the boss portion and to increase the flow passage area. In this regard, with the above configuration (4), Σt/L has the maximum value in at least the partial region, and the maximum value satisfies 0.5 or more. Thus, it is possible to effectively reduce the perimeter L of the boss portion and to increase the flow passage area in a region where Σt/L reaches the maximum value. Therefore, it is possible to increase the capacity of the compressor.
(5) In some embodiments, in the above configuration (4), a pair of compressor blades adjacent to each other in the circumferential direction are configured such that the fillet portions contact each other at a position where the ratio Σt/L reaches the maximum value, and a tangent direction of each of the fillet portions at a contact point between the fillet portions matches a tangent direction of a virtual arc defined by a diameter of the boss portion at the position.
Since the fillet portions for reducing a stress concentration are typically provided in the blade root parts, the ends of the fillet portions of the adjacent blades become close to each other as the diameter of the boss portion is reduced and eventually contact each other. If the diameter of the boss portion is further reduced from a state in which the ends of the fillet portions contact each other, the fillet portions contact each other via a discontinuous point, and the stress may be likely to concentrate in the vicinity of the discontinuous point. Therefore, while it is desirable to decrease the diameter of the boss portion with the object of increasing the flow rate, it is desirable to increase the diameter of the boss portion to some extent so the ends of the fillet portions of the adjacent blades do not contact each other via the discontinuous point from the perspective of durability of the blade root parts.
In this regard, with the above configuration (5), since the boss diameter is set which allows the fillet portions to be smoothly connected to each other at the position where the ratio Σt/L, reaches the maximum value, it is possible to improve durability of the compressor impeller by relaxing the stress concentration in blade roots while ensuring the large flow passage area.
(6) In some embodiments, in the above configuration (4) or (5), the ratio Σt/L of the total Σt of the blade thicknesses t to the perimeter L of the boss portion has the maximum value within a range where a meridional length ratio is not less than 0 and not greater than 0.5.
In the typical compressor impeller, the blade thicknesses t tend to relatively increase between the leading edges and a position where the meridional length ratio is 0.5, and the diameter of the boss portion tends to increase from the leading edges toward the trailing edges. Thus, with the above configuration (6), it is possible to reduce the diameter of the boss portion such that Σt/L has the maximum value between the leading edges and the position where the meridional length ratio is 0.5. At the position, the blade thicknesses t relatively increase, and the diameter of the boss portion relatively decreases. Thus, it is possible to effectively increase the flow passage area and to increase the capacity of the compressor.
(7) In some embodiments, in any one of the above configurations (1) to (6), the boss portion includes an inclined surface extending radially inward from an axial position of blade root parts on the leading edges of the compressor blades toward an upstream side and having an inclination angle θ of a tangent direction with respect to an axial direction in an axial cross-section, the inclination angle θ satisfying 0<θ[deg]≤30, and a ratio D3/D1 satisfies 0.5 or less, where D3 is a diameter of the boss portion at an upstream end of the inclined surface, and D1 is the diameter of the boss portion on the leading edges of the compressor blades.
With the object of improving efficiency of the compressor by smoothly guiding a flow on an inlet side of the impeller, it is desirable to suppress a disturbance in the flow on the upstream side of the leading edges of the compressor blades.
In this regard, with the above configuration (7), it is possible to form the shape of the boss portion from an upstream end of the inclined surface to the leading edges of the compressor blades to be continuous and smooth. It is also possible to form the shape of the boss portion to be suitable for obtaining a rectifying effect by adopting a configuration in which the inclination angle θ of the inclined surface satisfies 0<θ[deg]≤30, and the diameter ratio D3/D1 of the boss portion satisfies 0.5 or less. As a result, it is possible to suppress the disturbance in the flow and to smoothly guide the flow on the inlet side of the impeller, making it possible to improve efficiency of the compressor.
(8) In some embodiments, in the above configuration (7), the boss portion includes a tip part of a semi-elliptical shape having a major axis in the axial direction.
With the above configuration (8), it is possible to reduce a collision loss when the axial flow collides with the tip part of the boss portion and to improve efficiency of the compressor.
(9) A compressor according to some embodiments of the present invention includes the compressor impeller according to any one of the above configurations (1) to (8) and a compressor housing disposed so as to cover the compressor impeller.
With the above configuration (9), since the connection portion disposed on the side of the back surface of the impeller body is configured to be connectable to the one end of the rotational shaft as described in the above configuration (1), it is possible to configure the compressor impeller to be rotatable without providing the through hole for letting through the rotational shaft in the boss portion. Thus, it is possible to decrease the diameter of the boss portion on the leading edges of the compressor blades as compared with the structure of the impeller where the through hole is provided in the boss portion (through-bore structure). As a result, it is possible to increase the flow passage area of fluid guided to the compressor impeller, and thus it is possible to increase the capacity of the compressor while promoting downsizing thereof.
(10) A turbocharger according to some embodiments of the present invention includes the compressor according to the above configuration (9) and a turbine including a turbine impeller and configured to drive the compressor by an exhaust gas.
With the above configuration (10), since it is possible to increase the capacity of the compressor by increasing the flow passage area of air introduced into the compressor, it is possible to improve efficiency of the turbocharger.
According to at least one embodiment of the present invention, it is possible to provide a compressor impeller, a compressor, and a turbocharger capable of achieving a beneficial effect of increasing allow rate while promoting downsizing of the compressor.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
First, the overall configuration of a turbocharger to which a compressor impeller is applied according to some embodiments will be described with reference to
As shown in
In the compressor housing 20, an air inlet portion 24 for introducing air into the compressor housing 20 is formed. Air compressed by the rotation of the compressor impeller 22 passes through a diffuser flow passage 26 and a compressor scroll flow passage 28, and is discharged to the outside of the compressor housing 20 via an air outlet portion (not shown).
In the turbine housing 30, a gas inlet portion (not shown) for introducing an exhaust gas from an engine (not shown) into the turbine housing 30 is formed. The gas inlet portion can be connected to an exhaust manifold (not shown) of the engine. In addition, in an outer circumferential part of the turbine impeller 32 in the turbine housing 30, a scroll flow passage 36 is disposed so as to cover the turbine impeller 32. The scroll flow passage 36 communicates with the gas inlet portion and is formed so as to internally introduce the exhaust gas. The exhaust gas is guided from the scroll flow passage 36 to the turbine impeller 32, and is discharged to the outside of the turbine housing 30 via a gas outlet portion 39 after passing through the turbine impeller 32.
As described above, the turbocharger 1 can transmit a rotational force to the compressor impeller 22 via the rotational shaft 12 by rotary driving the turbine impeller 32 with the exhaust gas of the engine, centrifugally compress air entering the compressor housing 20, and supply the compressed air to the engine.
Next, an example of the shape of a boss portion of the compressor impeller 22 according to some embodiments will be described.
As a general structure of the compressor impeller 22, a through-bore structure in which the boss portion 41 has a through hole is known. In the through-bore structure, the rotational shaft 12 is typically fastened by a nut disposed on an inlet side of the impeller in order to fix the impeller body 45 and the rotational shaft 12 passing through the through hole. However, the through-bore structure in which the nut is disposed on the inlet side limits a reduction in the boss diameter D1 on the leading edges 51 even though it is desirable to reduce the boss diameter D1 on the leading edges 51 in order to ensure the capacity of the compressor 21 upon downsizing thereof.
Thus, in the present embodiment, a structure is adopted in which the rotational shaft 12 is connected to the connection portion 48 on the side of the back surface 46 of the impeller body 45, making it possible to configure the compressor impeller 22 to be rotatable without providing the through hole in the boss portion 41 (boreless structure). Unlike the through-bore structure, in the boreless structure, the boss portion 41 positioned on the leading edges 51 is not involved in fastening the compressor impeller 22 and the rotational shaft 12. Therefore, in the boreless structure, the boss diameter D1 on the leading edges 51 is set more flexibly, and it is possible to decrease the boss diameter D1 on the leading edges 51 of the compressor blades 43 as compared with the through-bore structure. Thus, it is possible to achieve the boss ratio D1/D2 not greater than 0.18 by adopting the boreless structure as in the present embodiment. As a result, as shown in the graph of
In some embodiments, as shown likewise in
According to the present embodiment, since the connection portion 48 disposed on the side of the back surface 46 of the impeller body 45 includes the fastening portion 49, it is possible to fix the one end of the rotational shaft 12 to the connection portion 48 by the fastening portion 49. Thus, it is possible to couple the rotational shaft 12 and the compressor impeller 22 to each other without providing a fastening member such as a nut on the side of the leading edges 51 of the compressor blades 43. Therefore, it is possible to promote the decrease in the diameter of the boss portion 41 on the side of the leading edges 51 of the compressor blades 43 and to increase the flow passage area, as also described in the above embodiment.
Further, in some embodiments, the boss portion 41 has a solid structure at least between the connection portion 48 and the leading edges 51. The solid structure refers to a state in which the interior is buried without having any through hole, groove, or the like.
According to the present embodiment, as compared with the through-bore structure in which a centrifugal stress is likely to be generated with concentration in the through hole, it is possible to disperse the centrifugal stress by adopting the solid structure. Accordingly, it is possible to effectively reduce a maximum centrifugal stress, and thus to increase the flow rate and improve durability of the compressor impeller 22 at the same time.
In the exemplary embodiment of
In the through-bore structure, the centrifugal stress generated in the through hole becomes maximum in the vicinity of the axial position where the impeller body 45 has the maximum outer diameter. Thus, according to the present embodiment, it is possible to improve durability of the compressor impeller 22 and to achieve the higher pressure ratio of the compressor 21 by adopting the solid structure at least in the range of the axial position where the maximum centrifugal stress can be generated to effectively disperse the centrifugal stress.
In the above description, “front” and “behind” are defined as follows. That is, in the axial direction, the side of the air inlet portion 24 as viewed from the compressor impeller 22 is referred to as “front”, and the side opposite to the air inlet portion 24 as viewed from the compressor impeller 22 will be referred to as “behind”.
Moreover, as shown in
The inclined surface 58 continuously exists in the axial direction from the axial position of the blade root parts 56 on the leading edges 51 toward the upstream side of the outer peripheral surface of the boss portion 41, and refers to an entire region satisfying 0<θ[deg]≤30. For example, if 0<θ[deg]<30 is satisfied at the axial position of the blade root parts 56 on the leading edges 51, the angle θ gradually increases toward the upstream side until the angle reaches 30 degrees at a particular axial position, and the angle θ exceeds 30 degrees on a further upstream side (the tip side of the boss portion 41), the axial position where the angle θ reaches 30 degrees is the upstream end 59 of the inclined surface 58. On the other hand, if the relation of 0<θ[deg]≤30 is satisfied over an entire range from the axial position of the blade root parts 56 on the leading edges 51 to an axial position at the tip of the boss portion 41, the tip of the boss portion 41 is the upstream end 59 of the inclined surface 58.
In the exemplary embodiment of
The advantageous effect of the present embodiment will be described as contrasted with the through-bore structure.
As shown in
In this regard, according to the present embodiment, it is possible to form the shape of the boss portion 41 from the upstream end 59 of the inclined surface 58 to the leading edge 51 of the compressor blade 43 to be continuous and smooth. It is also possible to form the shape of the boss portion 41 to be suitable for obtaining a rectifying effect by adopting a configuration in which the inclination angle θ of the inclined surface 58 satisfies 0<θ[deg]<30, and the diameter ratio D3/D1 of the boss portion 41 satisfies 0.5 or less. As a result, as shown in
According to the present embodiment, it is possible to prevent the tip part 61 from broadening in the radial direction by setting the major axis “a” of the ellipse in the axial direction of the compressor impeller 22. Thus, it is possible to reduce a collision loss when the axial flow collides with the tip part 61 of the boss portion 41 and to improve efficiency of the compressor 21.
Regarding the diameter of the boss portion 41 in an axial range from the leading edges 51 to the trailing edges 53 of the compressor blades 43, some embodiments will be described below with reference to
As shown in each of
If the boss diameter is further reduced from the state in which the ends of the fillet portions (63, 64) contact each other as shown in
Thus, in some embodiments, as indicated by a curve 100 of
The abscissa of the graph in
The blade thickness t denotes the blade thickness in the blade root part 56 of the compressor blade 43 including the fillet portion 63. As shown in
According to the present embodiment, the ratio Σt/I has the maximum value in at least the partial region, and the maximum value satisfies 0.5 or more. Thus, it is possible to effectively reduce the perimeter L of the boss portion 41 and to increase the flow passage area at a position where Σt/L reaches the maximum value. Therefore, it is possible to increase the capacity of the compressor 21.
Moreover, in some embodiments, as shown in
At this time, adding the blade thicknesses t of the compressor blades 43 in the circumferential direction, Σt becomes the same value as the perimeter L of the boss portion 41, and thus Σt/L becomes 1. In
According to the present embodiment, since the boss diameter is set which allows the fillet portions (63, 64) to be smoothly connected to each other at the axial position where the ratio Σt/L reaches the maximum value, it is possible to improve durability od the compressor impeller 22 by relaxing the stress concentration in the blade root parts 56 while ensuring the large flow passage area by decreasing the perimeter L relative to the total Σt of the blade thicknesses t.
In some embodiments, the ratio Σt/L of the total Σt of the blade thicknesses t to the perimeter L of the boss portion has the maximum value in a positional range where the meridional length ratio is not less than 0 and not greater than 0.5.
In the typical compressor impeller 22, the blade thicknesses t tend to relatively increase between the leading edges 51 and a position where the meridional length ratio is 0.5, and the diameter of the boss portion 41 tends to increase from the leading edges 51 toward the trailing edges 53. Thus, according to the present embodiment, it is possible to reduce the diameter of the boss portion 41 such that Σt/L has the maximum value between the leading edges 51 and the position where the meridional length ratio is 0.5. At the position, the blade thicknesses t relatively increase, and the diameter of the boss portion 41 relatively decreases. Thus, it is possible to effectively increase the flow passage area and to increase the capacity of the compressor 21.
Embodiments of the present invention were described in detail above, but the present invention is not limited thereto, and various amendments and modifications may be implemented.
Further, in the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
As used herein, the expressions “comprising”, “containing” or “having” one constitutional element is not an exclusive expression that excludes the presence of other constitutional elements.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/041128 | 11/15/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2019/097611 | 5/23/2019 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3961867 | Woollenweber | Jun 1976 | A |
| 7568883 | Arnold et al. | Aug 2009 | B2 |
| 20100202875 | Schlienger et al. | Aug 2010 | A1 |
| 20140314590 | Ising | Oct 2014 | A1 |
| 20150275921 | Pinkney et al. | Oct 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 103362557 | Apr 2016 | CN |
| 2 141 262 | Feb 1973 | DE |
| 50-30110 | Mar 1975 | JP |
| 57-167295 | Oct 1982 | JP |
| 63-79495 | May 1988 | JP |
| 8-326689 | Dec 1996 | JP |
| 2006-226199 | Aug 2006 | JP |
| 2009-209867 | Sep 2009 | JP |
| 2011-122539 | Jun 2011 | JP |
| 2013-185543 | Sep 2013 | JP |
| 2013-224614 | Oct 2013 | JP |
| Entry |
|---|
| Taburri et al., A model-based methodology to predict the compressor behaviour for the simulation of turbocharged engines, Jul. 29, 2011, pp. 560-574 (Year: 2011). |
| Turbo Rebuild Limited Woldwide Turbocharger Supplies, Billet Alloy Turbo Compressor Wheels, accessed 2020 (Year: 2020). |
| Office Action dated Jul. 13, 2020 issued in counterpart Chinese Application No. 201780092276.9 with Machine Translation. |
| International Preliminary Report on Patentability and the English translation of the Written Opinion of the International Searching Authority for International Application No. PCT/JP2017/041128, dated May 28, 2020. |
| International Search Report for International Application No. PCT/JP2017/041128, dated Feb. 20, 2018. |
| Extended European Search Reoprt dated Mar. 18, 2021 issued to the corresponding European Application No. 17931949.6. |
| Number | Date | Country | |
|---|---|---|---|
| 20200116158 A1 | Apr 2020 | US |
