JPH0642360A - Compressor for turbocharger - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a revolving stall throughout a whole operation area. CONSTITUTION:An inner housing 2 mainly composing a diffuser part 12 and an outer housing 3 mainly composing an inlet part 11 and a scroll part 13 are formed separately from each other. A scroll part 13 and a communicating passage 5 with which an inlet part 11 is communicated are formed between the inner and outer housings 2 and 3. The width of the communicating passage 5 is set to a value approximately equal to a tip clearance between an impeller 4 and the inner housing 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a compressor of a turbocharger which supercharges intake air by utilizing exhaust energy of an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional turbocharger compressor, for example, there is one shown in FIG. 4 (Japanese Patent Laid-Open No. 63-20541).
No. 9, gazette).

To explain this, the compressor housing 31 has an inlet portion 33 for introducing air from the axial direction of the impeller 32, a diffuser portion 34 for decelerating and pressurizing the air accelerated by the centrifugal force of the impeller 32, and this diffuser portion. A scroll-shaped scroll portion 35 that collects the pressurized air decelerated by 34 is integrally formed.

Communication holes 37 and 38 connecting the scroll portion 35 and the inlet portion 33 are formed in the compressor housing 31, and an electromagnetic valve 39 is provided in the middle of each of the communication holes 37 and 38.

When the throttle valve is fully closed during deceleration or the like, surging occurs due to a decrease in the air flow rate passing through the compressor when the impeller 32 rotates at high speed. Therefore, the solenoid valve 39 is opened when the throttle valve is fully closed, and the pressurized air of the scroll portion 35 is blown out to the inlet portion 33 through the communication holes 37 and 38 to prevent surging.

[0006]

However, when the intake air amount is small with respect to the increase in the rotational speed of the turbocharger even during acceleration of the engine, a turning stall similar to surging may occur temporarily.

However, in such a conventional device, when the solenoid valve 39 is opened, a large amount of flow flows back into the inlet portion 33 through the communication holes 37 and 38, and the solenoid valve 3 is accelerated during acceleration.
When 9 is opened, supercharging is not performed and the acceleration performance is extremely deteriorated. Therefore, the solenoid valve 39 cannot be opened during acceleration,
There is a problem that the operating range in which the solenoid valve 39 opens is limited.

The present invention focuses on the above problems and aims to solve them.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to an impeller for accelerating air by centrifugal force, an inlet for introducing air from the axial direction of the impeller, and a diffuser for decelerating and pressurizing the air accelerated by the centrifugal force of the impeller. In a compressor of a turbocharger, the inner housing mainly forming a diffuser part, and the outer housing mainly forming an inlet part and a scroll part, in a compressor of a turbocharger including a spiral part and a scroll-shaped scroll part for collecting pressurized air decelerated by the diffuser part. Are formed separately from each other, a communication passage that connects the scroll portion and the inlet portion is formed between the inner housing and the outer housing, and the passage width of the communication passage is formed to be substantially equal to the tip clearance between the impeller and the inner housing. .

[0010]

The air sucked from the inlet portion is accelerated by the centrifugal force of the impeller, decelerated and pressurized by the diffuser portion surrounding the impeller, and then collected in the spiral scroll portion, and connected to the outlet of the scroll portion. Is pumped to the body of the engine.

Due to the pressure difference between the scroll portion and the inlet portion, the pressurized air is ejected to the inlet portion through the communication passage. This jet of air activates the inlet of the impeller, making separation of the boundary layer less likely to occur, and moving the flow rate range in which turning stall occurs to outside the normal range, thus preventing vibration and noise due to surging. .

By forming the passage width of the communication passage to be substantially equal to the tip clearance between the impeller and the inner housing, the amount of intake air flowing back through each of the communication passages can be suppressed to a sufficiently small ratio with respect to the engine intake air amount. , It becomes possible to prevent the turning stall by opening the communication passage over the entire operating range.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 4 denotes an impeller which constitutes a compressor of a turbocharger provided in the engine, which rotates integrally with a turbine (not shown) driven by the energy of exhaust gas when the engine is operating, and sucks intake air by centrifugal force. It is designed to accelerate.

The compressor housing 1 includes an inlet portion 11 for introducing air from the axial direction of the impeller 4, a diffuser portion 12 for decelerating and pressurizing the air accelerated by the centrifugal force of the impeller 4, and a decelerating member for depressurizing the diffuser portion 12. And a scroll-shaped scroll portion 13 that collects compressed air.

The compressor housing 1 for accommodating the impeller 4 includes an inner housing 2 and an outer housing 3.
It is formed by dividing into. The inner housing 2 mainly forms the diffuser portion 12, and the outer housing 3
Mainly forms the inlet portion 11 and the scroll portion 13.

The outer peripheral portion of the inner housing 2 is a partition wall portion 2 which defines a diffuser portion 12 and a scroll portion 13.
1 is formed. The inner housing 2 and the outer housing 3 are each molded by die casting, and the partition wall portion 21 is separated from the outer housing 3 to facilitate the molding of the outer housing 3.

Between the inner housing 2 and the outer housing 3, four communication passages 5 that connect the scroll portion 13 and the inlet portion 11 are formed.

As shown in FIG. 2, the inner housing 2 has a joint surface 22 for the outer housing 3,
Four grooves 23 that define each communication path 5 are radially engraved on the joint surface 22.

An inner peripheral end 24 of the inner housing 22 is formed in an annular shape orthogonal to the rotation axis of the impeller 4. Since each groove 23 is carved at the inner peripheral end 24, the outlet 5a of each communication passage 5 is radially orthogonal to the rotation axis of the impeller 4.

The outlet 5a of each communication passage 5 is located at the inlet 11 of the compressor housing 1 and is located upstream from the upstream end 4a of the impeller 4 by a short distance. Therefore, the inner peripheral end 24 of the inner housing 22 is formed at a predetermined distance upstream from the upstream end 4A of the impeller 4 in the rotation axis direction of the impeller 4.

The width and depth of each groove 23, that is, the passage width of each communication passage 5 is formed to be substantially equal to the tip clearance which is the gap between the impeller 4 and the inner housing 2.

Next, the operation will be described.

The air sucked from the inlet portion 11 of the compressor housing 1 is accelerated by the centrifugal force of the impeller 4, decelerated and pressurized by the diffuser portion 12 surrounding the impeller 4, and then collected in the spiral scroll portion 13. It is pressure-fed to the engine body through an intake pipe connected to the outlet of the scroll portion 13.

Due to the pressure difference between the scroll portion 13 and the inlet portion 11 in the compressor housing 1, the pressurized air passes through each communication passage 5 and enters the inlet portion 11 at the center of rotation immediately upstream of the impeller 4 as indicated by the arrow in the figure. Ejects in the direction.
This jet of air activates the inlet portion of the impeller 4 and makes it difficult for the boundary layer to separate, thereby preventing a rotating stall. As a result, as shown in FIG. 3, in the conventional device, there was a flow rate region where the rotating stall was generated in the vicinity of the surge line, whereas in the present invention, the generation of the rotating stall was suppressed,
It is possible to prevent vibration and abnormal noise due to turning stall.

By forming the passage width of each communication passage 5 to be substantially equal to the tip clearance which is the gap between the impeller 4 and the inner housing 2, with respect to the engine intake air amount of the intake air flowing back through each communication passage 5. It can be suppressed to a sufficiently small ratio. This eliminates the need for a solenoid valve or the like that opens and closes each communication passage 5, and prevents a stall during turning over the entire operating range from the time of acceleration to the time of fully closing the throttle.

In addition, each communication passage 5 is connected to the inner housing 2
Since it is defined between the outer housing 3 and the outer housing 3, drilling or the like for the compressor housing 1 is not necessary when forming each communication passage 5, and the productivity is improved.

[0028]

As described above, according to the present invention, in the compressor of the turbocharger, the inner housing mainly forming the diffuser portion and the outer housing mainly forming the inlet portion and the scroll portion are formed separately from each other. , A communication passage that connects the scroll portion and the inlet portion is formed between the inner housing and the outer housing, and the passage width of the communication passage is formed to be approximately equal to the tip clearance between the impeller and the inner housing, so that the gas is ejected through the communication passage. The airflow can activate the inlet of the impeller to prevent vibration and abnormal noise due to stall during turning over the entire operating range.

[Brief description of drawings]

FIG. 1 is a sectional view of a compressor showing an embodiment of the present invention.

FIG. 2 is a front view of an inner housing of the same.

FIG. 3 is a characteristic diagram of an air amount and a pressure ratio of the compressor.

FIG. 4 is a sectional view of a conventional compressor.

[Explanation of symbols]

 1 Compressor Housing 2 Inner Housing 3 Outer Housing 4 Impeller 5 Communication Passage 11 Inlet 12 Diffuser 13 Scroll

Claims (1)

[Claims] 1. An impeller for accelerating air by centrifugal force, an inlet part for introducing air from the axial direction of the impeller, a diffuser part for decelerating and pressurizing the air accelerated by the centrifugal force of the impeller, and a decelerating part by the diffuser part. In a compressor of a turbocharger including a spiral scroll portion that collects pressurized air, an inner housing that mainly forms a diffuser portion and an outer housing that mainly forms an inlet portion and a scroll portion are formed by being divided from each other. In the turbocharger, a communication passage that connects the scroll portion and the inlet portion is formed between the inner housing and the outer housing, and the passage width of the communication passage is formed to be substantially equal to the tip clearance between the impeller and the inner housing. Compressor.