JPH07119476A - Turbocharger waist gate structure - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to reduce the pressure at the turbine rotor inlet to improve supercharging performance and to make the structure simple. A scroll chamber (17) provided in a flange portion (16) of a turbine housing (10) and communicating with a bypass passage (22), and a scroll chamber (1
7) and the exhaust outlet pipe (18) are communicated with each other, and the exhaust outlet (1) is formed by the flange portion (16) and the exhaust outlet pipe (18).
4) a nozzle portion (19) formed on the outer peripheral portion,
A wastegate structure for a turbocharger, characterized in that the cross-sectional area of the scroll chamber (17) gradually decreases as it approaches the exhaust outlet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger wastegate structure, and is used, for example, for supercharging pressure control of an automobile engine turbocharger.

[0002]

2. Description of the Related Art As a conventional technique for a wastegate structure of a turbocharger of this type, there is disclosed in Japanese Utility Model Laid-Open No. 63-17054.
There is one as shown in Japanese Patent Publication No. As shown in FIG. 4, a turbine housing 31 that houses the turbine rotor 30, an exhaust manifold 32 and an exhaust outlet pipe 33 that are respectively connected to the turbine housing 31, a bypass passage 34 that is branched from the exhaust manifold 32, and a bypass. A wastegate structure of a turbocharger having a wastegate valve 35 for bypassing exhaust gas from the passage 34 has a nozzle portion 36 provided immediately after the turbine rotor 30. The rotation of the turbine rotor 30 rises, the supercharging pressure of the compressor rotor 37 rises, and a prescribed amount or more of the air-fuel mixture is sucked into the combustion chamber, resulting in a severe temperature rise. As a result, the waste gate valve 35 is provided to control the supercharging pressure in order to prevent problems such as deterioration of the lubricating oil and deterioration of the strength of the material. However, the exhaust gas bypassed from the waste gate valve 35 flows out to the same exhaust outlet pipe 33 as the exhaust gas flowing out from the turbine rotor 30 side. Therefore, the turbine inlet pressure rises as the turbine outlet pressure rises,
The efficiency of supercharging performance will decrease. In order to solve this problem, a nozzle portion 36 is provided, and the nozzle portion 36 causes a flow velocity difference with the exhaust gas flowing out from the turbine rotor 30 side, and the exhaust gas flowing out from the turbine rotor 30 due to this ejector effect. Was sucked out to reduce the turbine inlet pressure.

[0003]

In the above-mentioned conventional technique, the nozzle portion is provided as a separate component in order to reduce the turbine inlet pressure. However, as shown in FIG. 4, the nozzle portion includes the exhaust outlet pipe 33. One end of the turbine rotor 30 is fixed to the central portion of the turbine rotor 30. However, since the fixed fixing portion blocks the flow of exhaust gas flowing out from the turbine rotor, the effect of supercharging performance is small. .
Moreover, the number of parts is increased and the cost is increased. Further, the structure is complicated, and therefore it is not suitable for miniaturization.

An object of the present invention is to reduce the pressure at the inlet of a turbine rotor to improve supercharging performance and to have a simple structure.

[0005]

Means for Solving the Problems The measures taken in the present invention in order to solve the above-mentioned problems include a turbine housing for accommodating a turbine rotor, an exhaust inlet and an exhaust outlet respectively provided in the turbine housing, and an exhaust inlet. In the wastegate structure of the turbocharger, which has a bypass passage branched from the bypass passage and a wastegate valve that controls the supercharging pressure by bypassing the exhaust gas from the bypass passage, the bypass passage is provided in the flange portion of the turbine housing. It has a scroll chamber that communicates with each other, and has a nozzle portion that communicates the scroll chamber and the exhaust outlet pipe and that is formed on the outer peripheral portion of the exhaust outlet by the flange portion and the exhaust outlet pipe, and the cross-sectional area of the scroll chamber is the exhaust outlet. It gradually decreases as it approaches.

[0006]

According to the above-mentioned means, the exhaust gas flowing from the bypass passage into the scroll chamber from the inlet is gradually accelerated because the cross-sectional area of the scroll chamber becomes smaller as it approaches the exhaust outlet. It is discharged to the exhaust outlet pipe. At this time, since the exhaust gas flows out at high pressure and high speed, there is a flow velocity difference with the exhaust gas from the turbine rotor side, and the exhaust gas on the turbine rotor side is sucked out by the ejector effect. As a result, the outflow of exhaust gas from the turbine rotor outlet is promoted, so the outlet pressure is reduced, and therefore the inlet pressure is also reduced, so that supercharging performance is improved. or,
By forming the scroll chamber in the flange part and forming the nozzle part in the outer peripheral part of the exhaust outlet by the flange part and the exhaust outlet pipe, the exhaust gas outlet passage is not narrowed, so resistance does not occur, and the number of parts is reduced. It can be reduced, leading to cost reduction. In addition, the above makes it possible to simplify the wastegate structure and reduce the size thereof.

[0007]

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

As shown in FIG. 1, the shaft 11 is
It is rotatably supported by a bearing 23,
An oil seal 24 is inserted through the shaft 11. The bearing 23 and the oil seal 24 are fixed to the bearing housing 25. An oil hole 26 for supplying oil to the bearing 23 is formed in the bearing housing 25. Further, a cooling water passage 27 for cooling the bearing housing 25 is formed. A turbine rotor 12 fixed to one end of a shaft 11 is housed in the turbine housing 10. Further, an exhaust inlet 13 and an exhaust outlet 14 are formed in the turbine housing 10. The exhaust inlet 13 is connected to an exhaust manifold (not shown), and the exhaust outlet 14 has an exhaust outlet pipe connected to the flange portion 16.

A compressor rotor 20 is housed in a compressor housing 21 on the left side of the shaft 11 in the figure, and is fixed to the shaft 11 which is rotationally driven by the turbine rotor 12.

As shown in FIG. 3, the exhaust inlet 13 is provided with a branched bypass passage 22.
Further, a waste gate valve 15 for controlling the supercharging pressure of the turbine rotor 12 is provided in the bypass passage 22 so that the exhaust inlet 13 and the bypass passage 22 can communicate with each other. This is because when the rotation of the turbine rotor 12 continues to rise, the supercharging pressure of the compressor rotor 21 also rises, and the air-fuel mixture exceeding the specified volume is sucked into the combustion chamber (not shown).
As a result, the temperature in the combustion chamber continues to rise, resulting in overheating. When overheated, problems such as deterioration of material strength, deterioration of lubricating oil, seizure or abnormal wear of pistons and valves, and occurrence of combustion such as knocking occur. To prevent this, the waste gate valve 15 is provided. Flange portion 1 of turbine housing 10
A scroll chamber 17 is formed in 6, and the outlet of the bypass passage 22 communicates with the scroll chamber 17.
Further, the inner peripheral side of the scroll chamber 17 is communicated with the inside of the exhaust outlet pipe 18 by a nozzle portion 19 formed by the exhaust outlet pipe 18 and the turbine housing 10.

As shown in FIG. 2, the scroll chamber 17 provided in the flange portion 16 can be formed with a simple structure and is gradually narrowed. The narrowed scroll chamber 17 allows the exhaust gas to be efficiently accelerated, and flows out uniformly from the entire circumference of the nozzle portion 19 to the exhaust outlet pipe 18. Further, since the nozzle portion 19 is formed by the turbine housing 10 and the exhaust outlet pipe 18, it is not necessary to separately provide a component, and the outlet of the exhaust outlet pipe 18 is not narrowed, so that exhaust gas resistance does not occur.

Next, the operation of this embodiment will be described.

When an engine (not shown) is started, supercharging by the turbocharger is started. That is, the exhaust gas of the engine (arrow A in FIG. 3) rotationally drives the turbine rotor 12, and together with the shaft 11, the compressor rotor 2
0 is rotated. The waste gate valve 15 provided for adjusting the intake pressure of the turbine rotor 12 in the high speed range is opened and closed by an actuator (not shown) provided on the compressor rotor 20 side. At this time, if the supercharging pressure exceeds a predetermined value. The actuator opens the waste gate valve 15 to connect the bypass passage 22 and the exhaust inlet 13. As a result, the boost pressure is kept below a certain value. The exhaust gas flowing out to the bypass passage 22 passes through the scroll chamber 17 and the exhaust outlet pipe 1
It is leaked to 8. At this time, the high-pressure exhaust gas in the scroll chamber 17 is flown out with its flow velocity increased by the nozzle portion 19. The exhaust gas flowing out from the turbine rotor 12 side has a slower flow velocity than the exhaust gas flowing out from the nozzle portion 19 into the exhaust outlet pipe 18, and a flow velocity difference is generated. Due to the ejector effect at this time, the exhaust gas flowing out from the turbine rotor 12 side is sucked out and discharged from the exhaust outlet pipe 18 (arrow B in FIG. 3). The smooth flow of the exhaust gas through the exhaust outlet pipe 18 reduces the pressure at the outlet of the turbine rotor 12. When the pressure at the outlet of the turbine rotor 12 is reduced, the pressure at the inlet of the turbine rotor 12 is also reduced, and the supercharging performance can be improved.

[0014]

According to the above-described invention, the exhaust gas flowing from the bypass passage into the scroll chamber from the inlet is gradually accelerated because the cross-sectional area of the scroll chamber becomes smaller as it approaches the exhaust outlet. Flow out into the exhaust outlet pipe. At this time, since the exhaust gas flows out at high pressure and high speed, there is a flow velocity difference with the exhaust gas from the turbine rotor side, and the exhaust gas on the turbine rotor side is sucked out by the ejector effect. As a result, the outflow of exhaust gas from the turbine rotor outlet is promoted, so the outlet pressure is reduced, and therefore the inlet pressure is also reduced, so that supercharging performance is improved.
Further, since the scroll chamber is formed in the flange portion and the nozzle portion is formed on the outer peripheral portion of the exhaust outlet by the flange portion and the exhaust outlet pipe, the exhaust gas outlet passage is not narrowed, so that resistance does not occur and the parts are The number of points can be reduced, leading to cost reduction. In addition, the above makes it possible to simplify the wastegate structure and reduce the size thereof.

[Brief description of drawings]

1 is a cross-sectional view of an embodiment according to the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a sectional view taken along line YY of FIG.

FIG. 4 is a cross-sectional view of a conventional turbocharger wastegate structure.

[Explanation of symbols]

 10 ... Turbine housing 12 ... Turbine rotor 13 ... Exhaust inlet 14 ... Exhaust outlet 15 ... Waste gate valve 16 ... Flange portion 17 ... Scroll chamber 18 ... Exhaust outlet pipe 19 ... Nozzle part 22 ... Bypass passage

Claims (1)

[Claims] 1. A turbine housing for accommodating a turbine rotor, an exhaust inlet and an exhaust outlet respectively provided in the turbine housing, a bypass passage branched from the exhaust inlet, and a flange portion of the turbine housing. In a wastegate structure of a turbocharger having an exhaust outlet pipe and a wastegate valve for controlling supercharging pressure by bypassing exhaust gas from the bypass passage, the bypass passage is provided in the flange portion of the turbine housing. A scroll chamber that communicates with each other, the scroll chamber and the exhaust outlet pipe are connected to each other, and the nozzle has a nozzle portion formed on the outer peripheral portion of the exhaust outlet by the flange portion and the exhaust outlet pipe. Characterized by the cross-sectional area gradually decreasing as it approaches the exhaust outlet Turbocharger waist gate structure.