JP3006215B2 - Centrifugal compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor for use in an exhaust gas turbocharger for generating a supercharging pressure for an engine.

[0002]

2. Description of the Related Art An exhaust gas turbine supercharger for supercharging an engine has, for example, an integral structure of a turbine having an impeller and a centrifugal compressor having an impeller through a bearing casing. And the impeller are connected by a shaft rotatably supported in the bearing compartment, the impeller is rotated by the exhaust of the engine, and the impeller is rotated through the shaft by the rotation of the impeller, The intake air is compressed by a centrifugal compressor and supplied to the engine.

In the centrifugal compressor used in the above-mentioned supercharger, as shown in FIG.
There is a characteristic that the compressor characteristic curve I enters the surging area A beyond the surge line S. Therefore, if the surge line S can be moved to the position of S 'toward the low flow rate, it can be adapted to a wider range of the operating range of the engine.

For this reason, conventionally, as shown in FIG. 3, a scroll-shaped compression flow path c is provided on an outer peripheral portion of an impeller a via a diffuser portion b, and projects forward from the impeller a from the diffuser portion b. And a housing d having a shroud wall that connects the impeller a to a turbine impeller (not shown) by an axle so that the impeller can be rotated via the axle by rotation of the impeller. In a certain centrifugal compressor, the shroud wall has a double wall structure of an outer wall f having an inlet e formed at a front end thereof and an inner wall h having an inlet g formed at a front end downstream of the inlet e. An annular chamber i is formed between the outer wall f and the inner wall h, and a slot (or hole) j for communicating between the chamber i and the impeller a is provided in the inner wall h. (Special Sho 62-178799).

According to the centrifugal compressor, the pressure in the region near the inlet g of the impeller a becomes lower than that in the chamber i during the high flow rate operation, so that the air flowing from the inlet g toward the impeller a is Separately, air also flows from chamber i through slot j toward impeller a, thereby increasing the amount of air reaching impeller a to increase its maximum flow capacity, while during low flow operation. Since the pressure in the region near the inlet g in the impeller a becomes higher than that in the chamber i, an air flow is generated from the portion of the impeller a through the slot j toward the chamber i, and the air is introduced from the inlet e into the inlet e. g to reduce flow capacity,
Thereby, the surge line S shown in FIG. 2 can be moved to the position of S ′.

[0006]

However, in the case of the centrifugal compressor, the slot j is provided in the inner wall h,
Although the maximum flow capacity at the time of high flow rate operation can be increased, the air discharge side of the chamber i is opened in the axial direction toward the intake port e side, so that it is easily affected by the suction drift and the dynamic pressure acts. Therefore, during the low flow rate operation, it is difficult for air to circulate from the impeller a side through the slot j, and as a result, the ability to move the surge line S in FIG. 2 to the low flow rate side is small.

Therefore, the present invention is to make it possible to move the surge line to a lower flow rate so that the operating range of the centrifugal compressor can be adapted to the operating range of the engine. .

[0008]

According to the present invention, an annular chamber is formed in a shroud wall extending forward from an outer peripheral portion of an impeller to form an air inlet. In addition, an opening that opens from the chamber in the direction of the impeller is provided, and a concave portion is formed in the outer peripheral portion on the intake port side of the shroud wall, and a penetrating portion that penetrates from the chamber toward the concave portion is provided. And a housing having a housing.

[0009]

When the suction pipe is connected to the suction port of the housing with a rubber band or the like, if the required gap is formed between the end face of the suction pipe and the edge of the suction port, the rotation speed of the impeller decreases. Then, a part of the air sucked by the impeller enters the chamber through the opening, and is further circulated to the impeller through the through portion, the concave portion, and the gap. Since the air discharge side of the chamber is not open toward the intake port side and is not easily affected by the inflow of suction, etc., a stable circulating flow can be obtained, so that the surge line can be moved to the low flow rate side. Become like

[0010]

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

FIG. 1 shows an embodiment of the present invention. An exhaust gas turbine having a housing 4 having a shroud wall 3 extending forward from an outer peripheral portion of an impeller 1 to form an intake port 2 is shown. In the centrifugal compressor for a turbocharger, an annular chamber 5 is formed in the shroud wall 3 of the housing 4 and an opening such as a slit or a hole opening from the chamber 5 toward the impeller 1. 6 and on the outer peripheral portion of the shroud wall 3 on the side of the intake port 2,
An annular concave portion 7 is formed with a step, and a penetrating portion 8 such as a hole or a slit penetrating from the chamber 5 toward the concave portion 7 is provided.

When the exhaust gas turbine turbocharger is installed in the engine room of the vehicle, normally, a suction pipe 10 is connected to the intake port 2 using a rubber band 11, and the rubber band 11 is fastened by a fastening fitting 12. However, in the present invention, at this time, the shroud wall 3 is installed such that a required gap 9 is formed between the edge of the intake port 2 and the end face of the suction pipe 10.

When the operation is performed in such a state, the air sucked from the intake port 2 by the rotation of the impeller 1 is sucked into a suction area by the impeller 1, compressed and supplied to a target place. During low flow rate operation, the pressure in a region near the inlet of the impeller 1 becomes higher than the pressure in the chamber 5.
Therefore, an airflow is generated such that a part of the air passing through the portion of the impeller 1 flows from the opening 6 into the chamber 5. On the other hand, the chamber 5 is connected to the intake port 2 through the through portion 8.
The air entering the intake port 2 through the suction pipe 10 because it communicates with the recess 7 on the outer peripheral side of the side and the gap 9 between the end edge of the intake port 2 and the end face of the suction pipe 10. The flow is above the gap 9
, The air in the chamber 5 is sucked through the penetrating portion 8, the concave portion 7, and the gap 9, and as a result, the negative pressure in the chamber 5 is increased, A part of the air passing through the part of the vehicle 1 is discharged from the gap 9 through the opening 6 through the chamber 5, and a circulating flow can be generated such that the air flows again toward the impeller 1.

As described above, by increasing the negative pressure in the chamber 5, the suction effect from the opening 6 can be increased. It can be kept out of the area. That is, the surge line S shown in FIG. 2 can be moved to the position of S ′ on the low flow rate side.

In the above, the penetrating part 8 on the air discharge side of the chamber 5 is provided with the concave part 7
And the concave portion 7 can also be opened radially through a gap formed between the end edge of the intake port 2 and the end surface of the suction pipe 10, so that the suction It is hardly affected, so that the air circulation can be obtained in a stable state. Further, since the penetrating portion 8 and the concave portion 7 are located on the outer peripheral side of the housing 4, the processing is easy.

The present invention is not limited to the above embodiment. The recess 7 formed in the outer peripheral portion of the shroud wall 3 on the side of the intake port 2 may not be annular.
Of course, slits may be provided at appropriate intervals in the circumferential direction, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0017]

As described above, according to the centrifugal compressor of the present invention, an annular chamber is formed in the shroud wall of the housing, and an opening is provided from the chamber to the position of the impeller. In addition, since a recess is formed in the outer peripheral portion of the shroud wall on the intake port side, and a penetrating portion communicating with the concave portion is provided from the chamber, the intake pipe is connected to the intake port using a rubber band or the like. At this time, by forming a gap between the end of the suction port and the end face of the suction pipe, a part of the air passing through the impeller portion during the low flow rate operation is reduced from the opening to the inside of the chamber. Circulating flow from the inside of the chamber to the direction of the impeller again through the penetrating portion, the concave portion, and the gap, and at this time, since the discharge side of the chamber does not directly face the air suction direction, the above The recirculation flow can be obtained in a stable state, so that the surge line can be shifted to the low flow rate side even under an operation condition of a low flow capacity that originally enters the surging region, and a wide range can be provided for the operating range of the engine. It can be adapted over a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of a centrifugal compressor of the present invention.

FIG. 2 is an example diagram showing a relationship between a flow rate and a pressure of a centrifugal compressor.

FIG. 3 is a schematic diagram illustrating an example of an exhaust gas turbine supercharger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impeller 2 Inlet 3 Shroud wall 4 Housing 5 Chamber 6 Opening 7 Depression 8 Penetration

Continuation of the front page (56) References JP-A-60-50298 (JP, A) JP-A-62-178799 (JP, A) JP-A-3-68599 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) F04D 29/40-29/56

Claims (1)

(57) [Claims] 1. An annular chamber is formed in a shroud wall extending forward from an outer peripheral portion of an impeller to form an air inlet, and an opening is opened from the chamber toward the impeller. A centrifugal compressor comprising: a housing provided with a recess, a recess formed in an outer peripheral portion of the shroud wall on the intake port side, and a penetrating portion penetrating from the chamber toward the recess.