JP2010138752A - Compressor and turbocharger for internal combustion engine equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compressor having a simple structure and inhibiting drop of efficiency at low flow rate and high flow rate, and a turbocharger for an internal combustion engine equipped with the same. <P>SOLUTION: The compressor 1 provided with a scroll part 2A extending in a scroll shape while gradually expanding channel area is disposed at a start part 7 which is a start of scroll of the scroll part 2A, and includes an elastic film 11 covering a part of an inner wall 10 of the scroll part 2A, and a communication path 15 connecting a space 12 formed between the elastic film 11 and the inner wall 10, and an outlet passage 8 which is an end of scroll of the scroll part 2A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a compressor provided with a scroll portion extending spirally while gradually increasing a flow path area, and a turbocharger of an internal combustion engine including the compressor.

  There is known a compressor in which a movable block is provided in an upstream portion of a scroll and the flow path area of the scroll is changed by moving the movable block in accordance with a flow rate (Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

Japanese Patent Laid-Open No. Sho 62-145946 JP 63-108524 A Japanese Patent Laid-Open No. 62-159732

  If the flow path cross-sectional area of the scroll part is made relatively small corresponding to a small flow rate, the efficiency at a large flow rate will decrease, and if formed relatively large corresponding to a large flow rate, the efficiency at a small flow rate will decrease. End up. In the compressor of Patent Document 1, the movable block is moved according to the flow rate to change the flow path cross-sectional area of the scroll portion. However, in this case, movement control of the movable block is required according to the mechanism for moving the movable block and the flow rate, so that the structure becomes complicated and the compressor becomes large. In addition, since the step is formed in the flow path by the movement of the movable block, the efficiency may be lowered depending on the operation region as compared with the housing without the movable block.

  Accordingly, an object of the present invention is to provide a compressor capable of suppressing a decrease in efficiency at a small flow rate and a large flow rate while having a simple structure, and a turbocharger of an internal combustion engine including the compressor.

The compressor according to the present invention is a compressor provided with a scroll portion extending in a spiral shape while gradually increasing the flow path area, and is provided at a start portion at the start of the spiral of the scroll portion. And a communication passage connecting a space formed between the elastic film and the inner wall and an outlet passage which is the end of the scroll of the scroll portion (Claim 1).

  According to this compressor, the space formed between the inner wall of the elastic film and the outlet passage of the scroll portion is connected by the communication passage. As a result, the pressure in the space formed between the elastic membrane and the inner wall, that is, the pressure inside the elastic membrane is the same as that in the outlet passage, so that it corresponds to the pressure difference between the outside and inside of the elastic membrane. Thus, the space inside the elastic membrane expands or contracts to change the flow path area of the start portion. The pressure difference that occurs between the outside and inside of the elastic membrane increases at low flow rates and decreases at high flow rates, so the space inside the elastic membrane is large at low flow rates and large at high flow rates. Get smaller. That is, the flow path area of the start portion is small when the flow rate is small and large when the flow rate is large. Therefore, the flow area of the start portion can be reduced when the flow rate is small and large when the flow rate is large by utilizing the pressure difference between the outside and the inside of the elastic membrane. However, a decrease in efficiency at a small flow rate and a large flow rate can be suppressed.

  A turbocharger for an internal combustion engine according to the present invention incorporates the above-described compressor, and drives a compressor wheel provided in the compressor by a turbine provided in an exhaust passage of the internal combustion engine. Since the turbine is driven by exhaust gas, the flow rate of the turbocharger compressor changes according to the amount of exhaust gas, that is, the operating state of the internal combustion engine. According to this turbocharger, since the compressor is incorporated, it is possible to suppress a decrease in compressor efficiency at a small flow rate and a large flow rate by changing the flow path area in response to a change in the flow rate. Therefore, efficient supercharging to the internal combustion engine can be realized.

  As described above, according to the present invention, the flow area of the start portion is reduced when the flow rate is small and increased when the flow rate is large using the pressure difference between the outside and the inside of the elastic membrane. Therefore, it is possible to suppress a decrease in efficiency at a small flow rate and a large flow rate while having a simple structure.

  FIG. 1 is an explanatory view schematically showing a scroll portion 2A of a compressor 1 according to an embodiment of the present invention. The compressor 1 is incorporated in a turbocharger mounted on the internal combustion engine, and supplies intake air to the engine body via the scroll portion 2A. Although not shown in detail, the turbocharger includes a compressor wheel provided at the center 4 of the compressor 1 and a turbine connected coaxially with the compressor wheel, and the turbine is provided in an exhaust passage of the internal combustion engine. Driven by exhaust. Then, the compressor wheel connected coaxially is driven by the turbine driven by the exhaust, and the air as the outside air is introduced into the scroll portion 2A by the rotation of the compressor wheel. An arrow 5 in FIG. 1 indicates the flow of air introduced into the scroll portion 2A.

  The scroll portion 2A extends in a spiral shape while gradually increasing the flow channel area from the start portion 7 having a small flow channel area toward the outlet passage 8 having a large flow channel area. And the edge part of the start part 7 is connected to the exit channel | path 8, and it is comprised so that the air introduce | transduced into the scroll part 2A can flow from the exit channel | path 8 to the start part 7, and can circulate. A compressor wheel (not shown) is provided at the center 4 of the compressor 1, and air is introduced from the center 4 as the compressor wheel rotates. An elastic film 11 covering a part of the inner wall 10 is provided on the start portion 7 of the scroll portion 2A. A space 12 sealed by the elastic film 11 and the inner wall 10 is formed inside the elastic film 11. The space 12 and the outlet passage 8 are connected via a communication passage 15.

  The elastic membrane 11 is configured to stick to the inner wall 10 in a state where no force is applied and to maximize the flow path area of the start portion 7. On the other hand, since the space 12 is connected by the outlet passage 8 and the communication passage 15, a pressure difference can be generated between the space 12 inside the elastic membrane 11 and the outside flow path. Due to this pressure difference, the volume of the space 12 changes and the elastic membrane 11 is expanded and contracted. FIG. 1 shows a state in which the force for expanding the space 12 inside the elastic film 11 and the elastic force for returning the elastic film 11 to the original inner wall 10 are balanced.

  FIG. 2 is an explanatory view schematically showing a scroll portion 2B provided in a conventional compressor. Components common to those in FIG. 1 are denoted by the same reference numerals in FIG. When the flow rate of the air flowing through the scroll portion 2B is a small flow rate, the pressure of the start portion 7 becomes lower than the pressure of the outlet passage 8. For this reason, in the compressor of FIG. 2, when the flow rate of the internal air is small, the air flows from the outlet passage 8 to the start portion 7 and the circulation indicated by the thick arrow 16 is promoted.

  FIG. 3 is a diagram showing the relationship between the flow rate of air introduced into the compressor and the pressure ratio in the compressor shown in FIG. The straight line 17 in FIG. 3 indicates a surge line, the curves 18 and 19 extending from the straight line 17 both indicate a uniform rotation line, and the broken line 20 indicates an operation line. In the operating area AR1 near the surge line where the flow rate is low, the compressor efficiency decreases due to the circulation of the introduced air. Therefore, the compressor efficiency becomes higher when there is no circulation of the introduced air. On the other hand, in the operating area AR2 near the choke flow rate where the flow rate is high, the compressor efficiency is increased due to the circulation of the introduced air. Therefore, if there is no circulation of the introduced air, the compressor efficiency is lowered. In the conventional compressor shown in FIG. 2, since circulation is promoted when the flow rate is small, the relationship between the surge line and the operating line is as shown in FIG. 3, and the compressor efficiency decreases in the operating area AR1 near the surge line. Will be invited.

  According to the embodiment shown in FIG. 1, the space 12 formed between the elastic membrane 11 and the inner wall 10 and the outlet passage 8 are connected by the communication passage 15, and the pressure in the space 12 formed inside the elastic membrane 11 is achieved. And the pressure in the outlet passage 8 become the same pressure. The space 12 inside the elastic membrane 11 expands according to the pressure difference between the space 12 inside the elastic membrane 11 and the flow path outside, and the volume changes. For this reason, in the small flow area AR1 in which the pressure difference between the pressure of the flow path outside the elastic membrane 11 and the pressure of the outlet passage 8 becomes large, the volume of the space 12 becomes large and the flow area of the start portion 7 becomes small. . As a result, the surge line shown in FIG. 3 moves in the upper left direction of FIG. In other words, the reduction of efficiency in the small flow rate region can be prevented by suppressing the circulation of air in the compressor 1 in the small flow rate region AR1.

  On the other hand, the pressure of the flow path formed outside the elastic film 11 in the start portion 7 is equal to the pressure in the outlet passage 8 or the elastic force of the elastic film 11 is greater than the force of the space 12 expanding due to the pressure difference. When it is large, the elastic film 11 sticks to the inner wall 10. As the flow rate of air flowing through the scroll portion 2A becomes larger, the difference between the pressure of the start portion 7 and the pressure of the outlet passage 8 becomes smaller. Therefore, in the region AR2 where the flow rate of air is large, the elastic film 11 in the start portion 7 The pressure difference between the outside and the inside becomes small, and the flow path area of the start portion 7 becomes the maximum. Thereby, the relationship between the surge line and the operating line shown in FIG. 3 is established, and the circulation of air in the compressor 1 is promoted. That is, the reduction of efficiency in the high flow rate region can be prevented by promoting the circulation of air in the compressor 1 in the high flow rate region AR2. That is, according to this embodiment, the circulation of the intake air is suppressed in the area AR1 where the flow rate of the intake air is small, while the circulation of the intake air is promoted in the area AR2 where the flow rate of the intake air is large. Accordingly, it is possible to suppress a decrease in efficiency in the small flow rate region and the large flow rate region while having a simple structure. Moreover, since it is a simple structure, the enlargement of the compressor 1 can be suppressed.

  However, this invention is not limited to the above-mentioned form, It can implement with a various form within the range of the summary of this invention. In the above-described embodiment, the compressor 1 is incorporated in the turbocharger mounted on the internal combustion engine, but is not limited to such a configuration. For example, the compressor 1 may be incorporated in a supercharger.

Explanatory drawing which showed typically the scroll part of the compressor which concerns on one form of this invention. Explanatory drawing which showed typically the scroll part provided in the conventional compressor. The figure which shows the relationship between the flow volume of the air introduced in the compressor of FIG. 2, and a pressure ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2A Scroll part 7 Start part 8 Outlet path 10 Inner wall 11 Elastic film 12 Space 15 Communication path

Claims (2)

In a compressor provided with a scroll portion extending spirally while gradually increasing the flow path area,
An elastic film that covers a part of the inner wall of the scroll part, and a space formed between the inner wall of the scroll part and the end of the spiral of the scroll part. A compressor comprising: a communication passage that connects a certain outlet passage.   A turbocharger for an internal combustion engine in which the compressor according to claim 1 is incorporated and a compressor wheel provided in the compressor is driven by a turbine provided in an exhaust passage of the internal combustion engine.

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