JPS63134815A - turbo charger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a double scroll turbocharger, and particularly to a double scroll turbocharger suitable for reducing thermal stress in a partition wall that partitions a scroll portion into two flow paths. It is something.

[Conventional technology]

As described in Japanese Patent Publication No. 56-1457, a conventional double-scroll type variable displacement turbocharger has a scroll portion of a turbine casing into which high-temperature exhaust gas flows, which is partitioned left and right by an annular partition wall to form two flow paths. The structure was such that exhaust gas could be introduced into only one side of the flow path, and the exhaust gas drove a radial flow turbine wheel, and a compressor connected to this wheel provided supercharging. However, no consideration was given to the thermal stress in the partition wall that occurs when high-temperature exhaust gas is rapidly introduced into only one side of the flow path.

[Problem that the invention seeks to solve]

In the above conventional technology, when high-temperature exhaust gas is rapidly introduced into only one side of the flow path, one side of the partition wall is rapidly heated, resulting in compressive bending thermal stress on that side and tensile bending stress on the other side. Occur. When these thermal stresses exceed the yield point of the material, plastic deformation occurs, and if this is repeated, there is concern that thermal fatigue failure may occur.

Fractures occur circumferentially and can lead to missing partition walls.

The present invention was made in order to solve the problems of the prior art described above, and the present invention is made in the case where high-temperature exhaust gas flows into only one of the two flow paths partitioned by a partition wall in the scroll portion of the turbine casing. The object of the present invention is to provide a double scroll turbocharger that can reduce the bending thermal stress generated in the partition wall and suppress the plastic deformation and thermal fatigue failure of the partition wall.

[Means for solving problems]

In order to achieve the above object, the configuration of the double scroll turbocharger according to the present invention is such that the scroll portion of the turbine casing into which high-temperature exhaust gas flows is divided by a partition wall to form two flow paths, and the exhaust gas is passed through the two flow paths. In a double scroll turbocharger configured to be introduced into only one of the flow paths, the exhaust gas drives a turbine wheel, and a compressor connected to the turbine wheel performs supercharging, wherein the partition wall A concave portion is formed on the outer surface of the scroll winding start portion of the turbine casing forming the root portion thereof along the outer periphery corresponding to the partition wall.

In addition, to add to the concept behind the development of the present invention, thermal stress is generated by restraining thermal deformation. Furthermore, a concave portion is formed along the outer periphery corresponding to the partition wall to reduce the bending rigidity of the root portion of the partition wall.

[Effect]

According to the above technical means, even if one side of the partition wall is rapidly heated by the inflow of high-temperature exhaust gas, the bending deformation of the partition wall becomes more free, so the restraining thermal stress is reduced -0 [Example] Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a longitudinal sectional view of a double scroll variable displacement exhaust turbocharger according to an embodiment of the present invention, FIG. 2 is a sectional view showing thermal deformation of a partition wall in a conventional casing, and FIG. FIG. 2 is a cross-sectional view showing thermal deformation of the partition wall in the casing of FIG. 1;

The turbine casing (hereinafter simply referred to as the casing) 1 shown in FIG. The scroll portion is partitioned in the radial direction by a partition wall 4 made of an annular disk so that the first and second secondary flow paths 2 and 3 are independent on the inner surface of the scroll of the casing.

On the outer periphery of this annular partition wall 4, that is, on the outer surface of the scroll winding start part of the casing forming the root of the partition wall,
A recess 5 is formed along the outer periphery of the partition wall 4 over a longitudinal portion of the partition wall 4 within a range of 180 degrees from the start of winding of the scroll.

A radial flow turbine wheel 6 is installed in the center of the interior of the casing 1, and a compressor 7 connected to the turbine wheel 6 supercharges the engine.

The valve 8 is for opening and closing the secondary flow path 3. When the engine is running at low speed, the valve 8 is closed and the exhaust gas is guided only to the narrow primary flow path 2, increasing the supercharging performance by increasing the gas flow rate. It is something.

Next, the function of thermal deformation of the turbine casing portion of such a double scroll type variable displacement exhaust turbocharger, particularly the partition wall, will be explained in comparison with the conventional technology.

When starting the engine, close the valve 8 and
High-temperature exhaust gas is introduced only to increase the flow velocity to effectively drive the turbine wheel 6. In this state, only the primary flow path 2 side of the partition wall 4 is rapidly heated by 1,1-', and becomes higher in temperature than the secondary flow path 3 side.

The temperature difference between the left and right sides of the partition wall 4 is large near the winding start of the long scroll of the partition wall 4 into which high-temperature exhaust gas flows, and becomes smaller as it approaches the winding end.

When a temperature difference occurs between the left and right sides of the partition wall 4, in the example of the prior art shown in FIG. Therefore, if this type of partition wall installation is a structure, the partition wall 4
As a result of the bending deformation of the partition wall 4' being restrained at its attachment part (root part), the deformation of the partition wall 4' becomes small as shown by the broken line, and the partition wall 4' has compression and a A high tensile stress is generated in the 2nd flow path 3#.

In contrast, in the present embodiment shown in FIG. 3, the outer periphery of the annular partition wall 4, that is, the root of the partition wall, is fixed inside the casing. Since the recess 5 is formed along the outer periphery corresponding to the partition wall 4 over a range of 180'' from the beginning, the bending rigidity at the base of the partition wall 4 is lower than that of the conventional example, and therefore the bending deformation of the partition wall 4 is reduced. becomes free as shown by the broken line, and the restraining thermal stress decreases.

Furthermore, since the recess 5 is formed, a thin connecting portion 9 is formed between the casing 1 on the primary flow path 2 side and the partition wall 4, and the casing 1 and the partition wall 4 on the secondary flow path 3 side form a thin connecting portion 9. Thus, a thin connecting portion 10 is formed. Since the connection part 9 between the casing 1 and the partition wall 4 on the primary flow path 2 side is thin and has a small heat capacity, the temperature rise in this part is accelerated, so that the expansion deformation of the partition wall 4 is reduced compared to the conventional example. As something free, stress can be reduced.

In order to fully exhibit these effects, it is necessary to adjust the wall thickness t2 of the primary flow path side connecting portion 9 and the wall thickness tδ of the secondary flow path side connecting portion 1o between the partition wall 4 and the casing 1 as shown in FIG. Harmony with (
It is desirable that t2+ta) is smaller than the wall thickness tz of the partition wall 4, and the casing 1 due to the internal pressure of high-temperature exhaust gas
(tz+ta) so that the connecting parts 9 and 10 are not deformed due to creep deformation of the outer periphery or vibration acceleration from the engine, and also so that the temperature of that part does not become higher than that of the partition U4 and generate an excessive tensile force in the radial direction. The value of is the plate thickness t of the partition wall 4
It should be set larger than 1/2 of i.

As described above, according to this embodiment, it is possible to reduce the bending thermal stress of the partition wall when high-temperature exhaust gas is rapidly introduced into only one side of the flow path of the casing, so that the plastic deformation and thermal stress of the partition wall can be reduced. It has the effect of suppressing fatigue fracture.

〔Effect of the invention〕

As described above, according to the present invention, bending heat generated in the partition wall occurs when high-temperature exhaust gas flows into only one of the two flow paths partitioned by the partition wall in the scroll portion of the turbine casing. It is possible to provide a double scroll turbocharger that can reduce stress and suppress plastic deformation and thermal fatigue failure of partition walls.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a double scroll variable displacement exhaust turbocharger according to an embodiment of the present invention, FIG. 2 is a sectional view showing thermal deformation of a partition wall in a conventional casing, and FIG. Casing in Figure 1...Casing, 2...
Primary flow path, 3...Second flow path, 4...Partition wall, 5
... recess, 6... turbine impeller, 7... compressor.

Claims (1)

[Claims] 1. The scroll portion of the turbine casing into which high-temperature exhaust gas flows is divided by a partition wall to form two flow paths, and the exhaust gas is configured to be introduced into only one of the two flow paths, and the exhaust gas flows into the turbine. In a double-scroll turbocharger that drives a blade wheel and performs supercharging by a compressor connected to the turbine wheel, the outer surface of the scroll winding start portion of the turbine casing, which forms the base of the partition wall, is provided with the A double scroll turbocharger with a recess formed along the outer periphery corresponding to the partition wall.