JP2002021574A - Compressor impeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance compression efficiency while reducing a stress applied to an impeller blade. SOLUTION: Long blades 18 and short blades 19 are arranged alternatively in a compressor impeller 16. An end edge 18a in an intake inlet side of the long blade 18 is formed linearly in the each blade 18, and an end edge 18b in an intake outlet side thereof is formed curvedly to be recessed with respect to a rotational direction (an arrow mark direction A1) of the impeller 16. An intake inlet side end edge 19a of the short blade 19 is formed curvedly to be protruded with respect to the rotational direction (arrow mark directalion A1) in the each blade 19, and an end edge 19b in an intake outlet thereof is formed curvedly to be recessed with respect to the rotational direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor impeller used for a compressor of a turbocharger for supercharging an internal combustion engine to compress intake air.

[0002]

2. Description of the Related Art As is well known, for example, from Japanese Utility Model Laid-Open Publication No. 3-52398, a turbocharger includes a turbine provided in an exhaust system of an internal combustion engine and a compressor provided in an intake system of the engine. It is configured. And
The impellers provided in the turbine and the compressor, that is, the turbine impeller and the compressor impeller are connected by one shaft so as to be able to rotate integrally. That is, when the turbine impeller is driven to rotate by the exhaust of the internal combustion engine, the rotation is transmitted to the compressor impeller through the shaft.
By rotating the compressor impeller in this way, the intake air to the internal combustion engine is compressed by the impeller blades (blades) of the compressor impeller, and the compressed intake air is forcibly pumped to the combustion chamber of the engine. . In the turbocharger, the output of the internal combustion engine is improved by performing supercharging using the energy of the exhaust gas.

In such a turbocharger, the compressor impeller is usually mounted radially from the inlet to the outlet of the air so as to maximize the air intake and increase the compression efficiency. The long blades (long wings) and the short blades (short wings) which are also radially attached only to the air outlet side are alternately arranged. And while taking a radiation structure by such a blade structure,
This ensures that both the securing of the intake air amount and the enhancement of the compression efficiency are suitably compatible.

[0004]

As described above, in the compressor impeller, by using the two types of impeller blades of the long wing and the short wing, a sufficient intake air amount is secured and the compression efficiency is also improved. Will be kept high. However, these two types of impeller blades are slightly different in the compressive action and the stress they receive. Therefore, it is desired to suitably match them, but no solution has been made yet.

[0005] Not only the compressor impeller of the turbocharger described above but also the compressor impeller having the two types of impeller blades of the long wing and the short wing for compressing the intake air, such a situation is generally common. It has become.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a compressor impeller capable of further improving the compression efficiency while reducing the stress applied to each impeller blade. It is in.

[0007]

The means for achieving the above object and the effects thereof will be described below. According to the first aspect of the present invention, long blades radially attached from the air inlet to the air outlet and short blades radially mounted only on the air outlet side are alternately arranged. In the compressor impeller which compresses the air sucked in from the inlet with the rotation and discharges the air to the outlet, at least one of the long blade and the short blade has the end on the outlet side having the compressor impeller. The gist has a shape curved in the circumferential direction.

[0008] According to the above structure, whether the blade is long or short, the stress applied to the end on the outlet side is smaller than that in the case where the end on the outlet side is a straight line generally used in the past. In addition, the compression efficiency is increased.

According to a second aspect of the present invention, in the compressor impeller according to the first aspect, at least one of the long blade and the short blade has an end on the outlet side in a rotational direction of the compressor impeller. The point is that it is curved in a concave shape.

According to the first aspect of the present invention, at least one end of the long blade and the short blade on the outlet side is curved in the circumferential direction of the impeller to reduce stress and reduce compression. Efficiency can be enhanced,
In particular, as in the configuration described above, by forming the curved direction concave with respect to the rotation direction of the impeller, the function and effect are further enhanced.

According to a third aspect of the present invention, in the compressor impeller according to the first or second aspect, the long blade is formed such that an end side on the inlet side is formed in a straight line. .

Particularly on the inlet side of the long blade,
Rather than compression efficiency, there is a strong demand for reducing the stress applied thereto. In this regard, according to the above configuration, the stress applied to the inlet side edge of the long blade can be suitably reduced.

According to a fourth aspect of the present invention, in the compressor impeller of the third aspect, the short blade has an inlet-side end curved in a convex shape with respect to a rotation direction of the compressor impeller. The gist is to become

According to the above construction, in the cross section perpendicular to the air flow direction at the end of the short blade at the inlet side, the rotation direction side surface of the long blade and the rotation direction of the short blade are The cross-sectional area (cross-sectional area of the air passage) with the opposite side surface is enlarged. Therefore, the resistance between the air and the side surfaces of the respective blades is reduced, and the compression efficiency is further improved.

According to a fifth aspect of the present invention, long blades radially attached from the air inlet to the air outlet and short blades radially mounted only on the air outlet side are alternately arranged. And with its rotation,
In the compressor impeller for compressing the air sucked in from the inlet and discharging the compressed air to the outlet, the elongated blade has a straight edge on the inlet side and a straight edge on the outlet side. Is formed in a concave shape with respect to the rotation direction of the compressor impeller, and the short blade is formed such that the end side on the inlet side is curved in a convex shape with respect to the rotation direction of the compressor impeller. The gist is that the end side on the outlet side is formed so as to be curved in a concave shape with respect to the rotation direction of the compressor impeller.

The function and effect of the edge shape of each blade are as described above. In particular, according to the above configuration, the best characteristics as a compressor impeller having these two types of blades are obtained in both the stress and the compression efficiency. Will be able to gain.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which a compressor impeller according to the present invention is applied to an impeller of a compressor of a turbocharger for supercharging an internal combustion engine will be described below with reference to FIGS. .

As shown in FIG. 1, a turbocharger 11 includes a turbine section 12 disposed in an exhaust passage of an internal combustion engine (not shown), a compressor section 13 disposed in an intake passage of the engine, And a connecting section 14 for connecting the section 12 and the compressor section 13.

The turbine section 12 includes a turbine impeller 1 rotated by exhaust gas discharged from a combustion chamber of the engine.
5 are provided. On the other hand, the compressor unit 13 includes:
A compressor impeller 16 that compresses intake air flowing through the intake passage and sends the compressed air to the combustion chamber is provided. These impellers 15 and 16 are integrally rotatably connected by a shaft 17 provided in the connecting portion 14.

The turbocharger 1 constructed as described above
At 1, the supercharging of the internal combustion engine is performed as follows.
That is, the exhaust gas discharged from the combustion chamber is
When the exhaust gas flows from the inlet 12a to the outlet 12b, the energy of the exhaust gas causes the turbine impeller 15
Is driven to rotate. Then, the rotation of the turbine impeller 15 is transmitted to the compressor impeller 16 of the compressor section 13 through the shaft 17, and the compressor impeller 16 is rotated. In the compressor section 13, the intake air flows into the inlet section 13a, and the introduced intake air is compressed by the rotation of the impeller 16, and the compressed intake air is forced from the outlet section 13b to the combustion chamber. To be pumped.

Here, as shown in FIGS. 2 and 3,
The compressor impeller 16 includes a long blade (long wing) 18 radially attached from the inlet 13 a to the outlet 13 b of the compressor 13,
Short blades (short wings) 19, which are also radially mounted only on the outlet 13b side, are alternately arranged.
FIG. 2 shows a perspective structure of the compressor impeller 16 viewed obliquely from its inlet, and FIG. 3 shows a front structure of the compressor impeller 16 viewed from the front of the inlet.

In the present embodiment, the long wing 18 and the short wing 19 have the following shapes as shown in FIGS. 2 and 3, respectively. That is, the long wing 18 has an inlet-side end 18a formed linearly and an outlet-side end 18b curved in a concave shape with respect to the rotation direction of the compressor impeller 16 (the direction of the arrow A1). Is formed. On the other hand, the short wing 19 has an end 19a curved in a convex shape with respect to the same rotational direction (the direction of the arrow A1), and an end 19b on the outlet side has a concave shape with respect to the same direction. Is formed.

Hereinafter, the reason why the long wing 18 and the short wing 19 are formed in such a shape will be described. FIG. 4 is a view showing the end sides 18a and 19a of the long wing 18 and the short wing 19 on the inlet side.
And shows the measurement results of the compression efficiency (compressor efficiency) ηc of the compressor section 13 when the compressor impeller 16 is rotated while the shapes of the end sides 18b and 19b on the outlet side are changed to linear and curved shapes, respectively. is there. This measurement was performed at the outlet 1 of the compressor unit 13.
The compressor efficiency ηc with respect to the corrected air flow rate Q is obtained by setting the pressure of 3b constant (106.4 kPa). Here, the corrected air flow rate Q is obtained by correcting the air flow rate flowing into the inlet portion 13a of the compressor section 13 by using the temperature and the pressure. In FIG. 4, the characteristic L1 indicated by a dashed line indicates the end sides 18a, 19a on the inlet side and the end side 18a on the outlet side of both the long wing 18 and the short wing 19.
b and 19b indicate the compressor efficiency characteristics of the linearly formed impeller, and the solid line characteristic L2 indicates the inlet-side edges 18a, 19a and the outlet-side edges 18b, 19b of both the long blade 18 and the short blade 19. Shows the compressor efficiency characteristics of the impeller curved in a concave shape with respect to the rotation direction.

As is apparent from the graph of FIG. 4, the respective ends 18a, 18b, 19a, 1
Compared with an impeller in which 9b is formed linearly, the compressor efficiency ηc can be improved by an impeller in which each of the end sides 18a, 18b, 19a, and 19b is formed in a concave shape with respect to the rotation direction. I understand. Although not shown in FIG. 4, the curved shape is not limited to a concave shape with respect to the rotation direction of the impeller, and may be a curved shape that is convex with respect to the rotation direction of the impeller. It has been confirmed by the inventor that the tendency is almost the same as the characteristic L2 indicated by the solid line.

FIGS. 5A and 5B show the long blades 18 each having a straight end, a concavely curved shape with respect to the rotational direction of the compressor impeller, and a curved shape with respect to the rotational direction of the impeller. When the compressor impeller is rotated, the same length wing 18 is formed.
3 shows the measurement results of the stress generated in the test. In this measurement, the peripheral speed of the impeller was kept constant (50
0 m / s), the FEM (Finite Element Method) calculated value of the von Mises stress at the root near the inlet and outlet sides 18a and 18b on the side surface of the long blade 18 is shown. In FIG. 5, the side surface of the long blade 18 on the rotation direction side of the impeller is defined as P (pressure) side, while the side surface of the long blade 18 opposite to the rotation direction of the impeller is defined as S (suction) side. Notation.

First, on the outlet side of the long blade 18, the end side 18b is formed to be curved in a convex shape with respect to the rotation direction of the compressor impeller with respect to the stress value when the end side 18b is formed linearly. In this case, the stress value on the S side surface is low, but the stress value on the P side surface is high. On the other hand, when the end side 18b is curved in a concave shape with respect to the rotation direction of the impeller, the stress values on the S and P side surfaces are both low (see the numerical value surrounded by the circle a).

Thus, it can be seen that the effect of reducing the stress on the outlet side of the long blade 18 is further enhanced when the end 18b is curved in a concave shape with respect to the rotation direction of the impeller. On the other hand, with respect to the inlet side of the same length wing 18, the same side 18 a is set in the rotation direction of the compressor impeller with respect to the stress value when the end 18 a is formed in a straight line (see the numerical value surrounded by a circle b). On the other hand, in the case of forming a curve in a convex shape, the stress value on the P side surface is low, but the stress value on the S side surface is large (see the numerical value surrounded by a circle c). On the other hand, when the end side 18a is formed in a concave shape with respect to the rotation direction of the impeller, the stress values of the S and P side surfaces are both large.

As a result, it can be seen that, on the inlet side of the long blade 18, the stress is suitably reduced by forming the end 18 a straight. Here, although illustration is omitted in FIG. 5, regarding the value of the stress generated in the short wing 19,
The outlet side shows almost the same tendency as the stress value generated in the case of each shape of the end side 18b of the long wing 18, and the inlet side shows the same tendency as the stress value generated in the case of each shape of the end side 18a of the long wing 18. It has been confirmed by the inventors that the value is slightly lower.

As a result, the short wing 19 can also be used for the long wing 18
In the same manner as in the case of
It can be seen that the stress is reduced by forming the end side 19a of the inlet side of the compressor into a concave shape with respect to the rotation direction of the compressor impeller, while forming the end side 19a straight.

On the other hand, as shown in FIG.
In the case where the inlet sides 18a, 19a of the short wing 8 and the short wing 19 are both formed in a straight line, the end 19 of the short wing 19 is usually formed.
a, a section parallel to the end face 16a of the impeller (a-a
Passage A through which the intake air passes (line section)
And the passage cross-sectional area B1 of the passage B through which the intake air passes also becomes equal. In addition, the long wing 18
The blade angle in the vicinity of the end side 18 a is formed to be larger on the minus side than the blade angle in the vicinity of the end side 19 a of the short wing 19. That is, the long blade 18 is formed such that the bb line portion is inclined more toward the rotation direction of the impeller 16 than the aa line portion. Therefore, the edge 1 of the short wing 19
The cross-sectional area A2 of the passage A in the cross section (cross-section taken along the line cc) perpendicular to the flow direction of the intake air passing through the passage 9a is smaller than the cross-sectional area B2 of the passage B. As a result,
The flow rate of the intake air passing through the passage A becomes smaller than the flow rate of the intake air passing through the passage B. Accordingly, a difference occurs in the manner of deceleration between the passage A and the passage B, which causes a reduction in compressor efficiency.

In this regard, as in the above-described structure of the present embodiment, the end 19a of the short wing 19 is connected to the compressor impeller 1
By curving the passage A in a convex shape with respect to the rotation direction, the passage A has a larger cross-sectional area, and the entrance areas of the passage A and the passage B can be made substantially equal. As a result, the compressor efficiency ηc is improved. In this case, the edge 19a of the short wing 19 may be curved so that the deceleration of the relative speed of the intake air passing through the passage A and the deceleration of the relative speed of the intake air passing through the passage B are substantially equal. It is considered that this is desirable for further improving the compressor efficiency ηc.

Based on the above measurement results and the principle shown in FIG. 6, the long blade 18 forming the compressor impeller 16 is formed.
And the short wings 19 include (a) the end sides 18b, 1
9b is formed in a concave shape with respect to the rotation direction of the impeller 16;

(B) The edge 18a on the inlet side of the long blade 18 is formed linearly. (C) The edge 19a on the inlet side of the short wing 19 is formed to be curved in a convex shape with respect to the rotation direction of the impeller 16. However, while reducing the stress, the compression efficiency (compressor efficiency) η
It turns out that it is effective in increasing c.

As described in detail above, according to the compressor impeller of this embodiment, the following excellent effects can be obtained. (1) The end sides 18b, 1 on the exit side of the long wing 18 and the short wing 19
9b is curved in a concave shape with respect to the rotation direction of the compressor impeller 16, so that the effect of reducing the stress generated on the outlet side edges 18b, 19b of the long blade 18 and the short blade 19 is further enhanced. .

(2) Since the end 18a on the inlet side of the long blade 18 is formed in a straight line, the stress applied to the end 18a can be reduced appropriately. (3) Since the end 19a on the inlet side of the short blade 19 is curved in a convex shape with respect to the rotation direction of the compressor impeller 16, the compressor efficiency ηc is further improved.

(4) The long wing 18 has an end 18 on the inlet side.
a is formed in a straight line, and the outlet side 1
8b is curved in a concave shape with respect to the rotation direction of the impeller 16, and the short wing 19 has an end side 19a on the inlet side thereof.
6, and the end 19b on the outlet side is curved in a concave shape with respect to the rotation direction of the impeller 16, so that both sides of the stress and the compressor efficiency ηc The best characteristics as the impeller 16 including the two types of long wings 18 and short wings 19 can be obtained.

The configuration of the above embodiment can be appropriately changed as follows, for example. In the above embodiment, the edge 18a on the inlet side of the long wing 18
Are formed in a straight line, and the end side 19a on the inlet side of the short wing 19 is formed to be curved in a convex shape with respect to the rotation direction of the compressor impeller 16. However, long wing 1
The end 18a of the short wing 8 may be formed in a concave shape with respect to the rotation direction of the impeller 16, and the end 19a of the short wing 19 may be formed in a straight line. Further, both the long sides 18a and 19a of the long wing 18 and the short wing 19 may be formed to be curved in a convex shape or a concave shape with respect to the rotation direction of the impeller 16.

In the above embodiment, both the end 18b on the outlet side of the long blade 18 and the end 19b on the outlet side of the short blade 19 are formed to be curved in a concave shape with respect to the rotation direction of the compressor impeller 16. Although the configuration has been described, these edge sides 18b, 1
9b may be configured to be curved in a concave shape in the same direction.

In the above embodiment, the edge 1 of the long wing 18
8b and both ends 19b of the short wings 19 are configured to be curved in a concave shape with respect to the rotation direction of the compressor impeller 16, but at least one of these ends 18b, 19b is formed in the circumferential direction of the compressor impeller 16. It may be configured to be curved.

In addition, technical ideas that can be grasped from the above embodiment and the above description will be described below. (B) The compressor impeller according to any one of claims 1 to 5, wherein the compressor impeller is an impeller provided in a compressor of a turbocharger that supercharges an internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a turbocharger to which an embodiment of a compressor impeller of the present invention is applied.

FIG. 2 is a perspective view of the compressor impeller of the embodiment.

FIG. 3 is a front view of the compressor impeller.

FIG. 4 is a graph showing a compressor efficiency with respect to a corrected air flow rate.

FIG. 5 is a diagram showing values of stress generated in a long wing.

FIG. 6 is a partial cross-sectional view showing a cross section of a part of a long wing and a short wing.

[Explanation of symbols]

11 Turbocharger 12 Turbine section 13 Compressor section 12a 13a Inlet section 12b 13
b ... outlet part, 14 ... connecting part, 15 ... turbine impeller,
16 ... Compressor impeller, 17 ... Shaft, 18 ...
Impeller blades (long wing), 19 ... Impeller blades (short wing), 18a, 18b, 19a, 19b ... end sides.

Claims (5)

[Claims] 1. Long blades radially attached from an air inlet to an air outlet and short blades also radially mounted only on an air outlet side are alternately arranged, and with rotation thereof, In a compressor impeller for compressing air sucked from the inlet and discharging the compressed air to the outlet, at least one of the long blade and the short blade has an end on the outlet side in a circumferential direction of the compressor impeller. A compressor impeller characterized by having a curved shape. 2. The compressor according to claim 1, wherein at least one of the long blade and the short blade has an end on the outlet side curved in a concave shape with respect to a rotation direction of the compressor impeller. Impeller. 3. The compressor impeller according to claim 1, wherein the elongated blade has a straight end on the inlet side. 4. The compressor impeller according to claim 3, wherein said short blade has an inlet-side end curved in a convex shape with respect to a rotation direction of said compressor impeller. 5. A long blade radially attached from an air inlet to an air outlet and a short blade radially attached only to an air outlet side are alternately arranged, and with rotation thereof, In the compressor impeller for compressing the air taken in from the inlet and discharging the compressed air to the outlet, the long blade has a straight edge on the inlet side and a straight edge on the outlet side. Is formed in a concave shape with respect to the rotation direction of the compressor impeller, and the short blade is formed such that the end side on the inlet side is curved in a convex shape with respect to the rotation direction of the compressor impeller. The compressor impeller is characterized in that the end side on the outlet side is curved in a concave shape with respect to the rotation direction of the compressor impeller.