JPH10339152A - Centrifugal compressor for turbo charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently actuate a guide vane to provide rotation to an air current flowing into a runner. SOLUTION: In a centrifugal compressor to be used in a turbo charger to supply high pressure air to a cylinder in an engine, plural guide wanes 13 are provided around an air entrance concentric to a runner 2 at a front side position of the entrance around the runner 2 in such a way that an inclination angle from an axial center direction of the runner 2 is adjustable, where a flow regulator 21 is provided at a front side position of a hub part at a center part of the runner 2 in the axial center direction of the runner 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor used for a turbocharger for supplying high-pressure air to an engine cylinder.

[0002]

2. Description of the Related Art A turbocharger has been invented in which the pressure ratio of a centrifugal compressor can be increased even in the low-speed range of an engine, thereby improving acceleration performance by supercharging and reducing exhaust emissions.

[0003] In this turbocharger, as disclosed in Japanese Patent Application No. 8-180512, a centrifugal compressor is provided with air for turning air flowing into a rotating impeller in the same direction as the impeller. A flow swirl mechanism is provided so that the swirl amount can be adjusted.

In the low-speed region of the engine, the swirl applied to the airflow flowing into the impeller is increased, and in the high-speed region of the engine, the swirl applied to the airflow flowing into the impeller is reduced or made zero.

[0005] The air flow swirling mechanism has a shaft in the radial direction of the impeller at a plurality of positions sandwiching the center of the air inlet concentric with the impeller, and a guide blade is fixed to each shaft. The guide vanes are respectively arranged in front of the entrance of the impeller, and the guide vanes for turning the airflow flowing into the impeller are provided so as to adjust the inclination angle of the impeller from the axial direction.

[0006] The shaft of the guide blade is connected to a rotary drive device for rotating the shaft by a desired angle, and a control device for controlling the rotary drive device according to the rotation speed of the engine is provided.

[0007]

However, in the centrifugal compressor for a turbocharger as described above, the air flow swirling mechanism arranges a plurality of guide vanes around the air inlet, and the center of the air inlet Since nothing is arranged in the section, when the inclination angle of the guide vanes from the axial center direction of the impeller, that is, the angle of attack of the guide vanes with respect to the air flow is increased in the low speed range of the engine, the guide around the air inlet is guided. The flow resistance due to the blades increases, the proportion of the air flow passing around the air inlet with the guide vanes decreases, and the proportion of the air flow passing through the center of the air inlet without the flow path resistance with the guide vanes decreases. To increase.

Therefore, in the low-speed range of the engine, the guide vanes for turning the air flow flowing into the impeller do not sufficiently act, and even if the guide vanes are greatly inclined from the axial center of the impeller, they are still relatively small. Does not give a large swirl to the airflow.

Further, since the air flow passing through the center of the air inlet collides with the hub at the center of the impeller, the loss increases as the proportion of the air flow increases.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a centrifugal compressor used for a turbocharger for supplying high-pressure air to an engine cylinder, wherein a plurality of guide blades are provided around an air inlet concentric with an impeller. Is provided at the front side of the entrance of the periphery of the impeller so that the inclination angle of the impeller from the axial center direction can be adjusted, and the air flow flowing into the rotating impeller is turned in the same direction as the impeller, A straightening body is provided at the center of the air inlet at a position in front of the hub at the center of the impeller in the axial direction of the impeller.

[0011]

According to the present invention, since the guide vanes are arranged at the periphery of the air inlet and the rectifier is arranged at the center of the air inlet, the guide vane inclination angle from the axial center direction of the impeller is provided. That is, even if the angle of attack of the guide vanes with respect to the air flow is increased, the air flow passes through the periphery of the air inlet with the guide vanes and does not pass through the center of the air inlet with the rectifier.

Therefore, the guide vanes for imparting swirl to the airflow flowing into the impeller function sufficiently.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Example (see FIGS. 1 to 4)> This example is a centrifugal compressor used for a turbocharger of an automobile engine.

In this centrifugal compressor, as shown in FIG. 1, an impeller 2 is placed in the center of a casing 1 and a shaft 3 of the impeller 2
Is provided at the rear of the casing 1, and an air inlet pipe 4 is provided at the front of the casing 1 so as to be concentric with the impeller 2.
A diffuser 5 and a swirl chamber 6 are provided concentrically inside and outside on the outer peripheral portion. Although not shown, an air outlet pipe is connected to the large diameter portion of the spiral chamber 6.

As shown in FIG. 1, the impeller 2 has a shaft 3 concentrically penetrating the center of a disk-shaped main plate 7 and a screw of the shaft 3 protruding forward of a hub at the center of the main plate 7. A nut 8 is screwed into the tooth end and tightened, the main plate 7 is fixed to the shaft 3, and curved plate-shaped blades 9 are fixed to the front surface of the peripheral portion of the main plate 7 at substantially equal intervals along a substantially radial direction. I have.

The air flowing through the intake passage of the engine flows from the air inlet pipe 4 of the centrifugal compressor to the inlet at the front peripheral portion of the impeller 2, passes through the curved passage between the blades 9 of the impeller 2,
From the outlet on the outer periphery of the impeller 2, the air flows into the swirl chamber 6 via the diffuser 5, and the high-pressure air flows into the cylinder of the engine from the air outlet pipe of the swirl chamber 6. The exhaust gas flowing through the exhaust passage of the engine rotates the gas turbine, and the gas turbine rotates the centrifugal compressor.

As shown in FIG. 1, the centrifugal compressor has an air inlet concentric with the impeller 2, which gives an airflow flowing into the rotating impeller 2 a turn in the same direction as the impeller 2. The flow swirl mechanism 11 is provided so that the swirl amount can be adjusted.

As shown in FIGS. 1 and 2, the air flow swirling mechanism 11 penetrates the shaft 12 in the radial direction of the air inlet pipe 4 at equal intervals in the circumferential direction of the cylindrical air inlet pipe 4. Each of the shafts 12 projecting into the air inlet pipe 4 is fixed to the base end of a substantially fan-shaped guide blade 13 along the axial direction of the shaft 12 at the inner end of each shaft 12. The guide blades 13 whose width in the axial direction of the air inlet pipe 4 becomes narrower as approaching the axis of the pipe 4 are arranged at equal intervals at the front side of the inlet on the front surface of the periphery of the impeller 2.

As shown in FIG. 1, the outer end of each shaft 12 projecting out of the air inlet pipe 4 is connected to a rotary drive device 14 for rotating the shaft 12 by a desired angle. Each guide blade 13
Respectively, the rear side of the guide blade 13 is turned in the direction of movement of the blade 9 of the impeller 2 facing the guide blade 13 so as to be tiltable, and as shown in FIG. And the angle α inclined from the axis of the impeller 2 can be adjusted.

Further, there is provided a control device 15 for controlling the rotation drive device 14 of the guide blade 13 according to the rotation speed of the engine. In the low-speed region of the engine, the inclination angle α of the guide blade 13 is increased to increase the turning given to the airflow flowing into the impeller 2, and in the high-speed region of the engine, the guide blade 1
3 is made small or zero, and the rotation given to the airflow flowing into the impeller 2 is made small or zero.

At the center of the air inlet, which is concentric with the impeller 2, a rectifier 21 is provided in the axial direction of the impeller 2 at a position in front of the hub at the center of the impeller 2.

The rectifier 21 is, as shown in FIGS. 1 and 2,
It has a round shaft shape with the front end smoothly pointed, and the air inlet pipe 4
The center end of the straightening body 21 is located close to the leading end of the guide blade 13 at the center of the impeller 2 and immediately before the hub. A plurality of wing-shaped support plates 22 are fixed at equal intervals between the front side of the rectifier 21 protruding forward of the guide blades 13 and the inner peripheral surface of the air inlet pipe 4. ing.

In the centrifugal compressor of this embodiment, the guide vanes 13 are arranged around the air inlet, which is concentric with the impeller 2, while the rectifier 21 is arranged at the center of the air inlet. The air flow f flowing through the air inlet pipe 4 does not flow through the central portion of the rectifier 21 when it reaches the rectifier 21 as shown in FIG. It flows around the guide blade 13 and passes through the space between the guide blades 13 and flows into the entrance on the front surface of the peripheral portion of the impeller 2.

Therefore, even if the inclination angle α of the guide blade 13 is large, the guide blade 13 that turns the air flow f flowing into the impeller 2 works sufficiently.

In the centrifugal compressor of this embodiment, the case where the straightening body 21 is provided and the case where the straightening body 21 is not provided are respectively described below.
The turning angle of the airflow f at the inlet position of the impeller 2 was determined. As is clear from FIG. 4, the inclination angle α of the guide blade 13 is set to 3
Whether you set it to 0 degrees or 60 degrees,
When the rectifier 21 is provided, the turning angle of the airflow f at the entrance position of the impeller 2 becomes larger.

<Second Example (See FIG. 5)> The centrifugal compressor of the present example differs from the previous example in the support structure of the rectifier 21.

As shown in FIG. 5, a support shaft 31 is provided at the tip of each guide blade 13 coaxially with the shaft 12 at the base end of the guide blade 13 without providing the support plate 22 in the previous example. Rectifier 2 sandwiched close to the tip of guide vane 13
The same number of support holes 32 as the number of support shafts 31 are provided at the center of the support shaft 1, and the support shafts 31 at the tips of the guide blades 13 are rotatably fitted into the respective support holes 32, and the straightening body 21 is connected to the shaft of the impeller 2. It is provided at the front side of the hub in the center of the impeller 2 in the core direction.

In the previous example, there is no loss caused by the air flow f flowing through the air inlet pipe 4 hitting or contacting the support plate 22.

The other points are the same as in the previous example.

<Third example (see FIG. 6)> The centrifugal compressor of the present example is different from the previous two examples in the support structure of the rectifier 21.

The support plate 22 in the first example and the support shaft 31 in the second example are not provided, and a screw hole 41 is provided concentrically at the rear end of the rectifier 21 as shown in FIG. Screw hole 41
Instead of the nut 8 in the previous two examples, the attached rear end is screwed into the threaded end of the shaft 3 protruding to the front side of the impeller 2 and tightened, and the front side is pinched close to the tip of the guide blade 13. Rectifier 2
1 is provided concentrically connected to the front of the hub portion at the center of the impeller 2.

The structure for supporting the flow regulating member 21 is simpler than the structure for supporting the straightening body 21 in the previous two examples.

The other points are the same as in the previous example.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a centrifugal compressor for a turbocharger according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged cross-sectional view taken along line BB of FIG. 1;

FIG. 4 is a diagram showing the relationship between the swirling angle of the airflow at the impeller inlet and the dimensionless distance from the shaft center in the centrifugal compressor of the first example and the centrifugal compressor without a rectifier.

FIG. 5 is a longitudinal sectional view of a centrifugal compressor for a turbocharger according to a second example of the embodiment.

FIG. 6 is a longitudinal sectional view of a centrifugal compressor for a turbocharger according to a third example of the embodiment.

[Explanation of symbols]

 2 impeller 13 guide blade 21 commutator

Claims (1)

[Claims] 1. A centrifugal compressor used for a turbocharger for supplying high-pressure air to a cylinder of an engine, wherein a plurality of guide blades are arranged around an air inlet concentric with the impeller from an axial direction of the impeller. Is provided at a position in front of the entrance around the impeller so that the inclination angle of the impeller can be adjusted so that the air flowing into the rotating impeller is turned in the same direction as the impeller. A centrifugal compressor for a turbocharger, wherein a fluid is provided at a position in front of a hub portion at a center portion of the impeller in the axial direction of the impeller.