JPS61218734A - Exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To prevent the generation of crack in the vicitity of a tongue part by forming a slit or a thin part which extends in the radial direction of a turbine in the vicinity of the tongue part at the swirl starting part of an exhaust- gas introducing passage on a partitioning wall. CONSTITUTION:A turbine casing 21 is divided into the first exhaust gas passage 27 and the second exhaust gas passage 28 by a partitioning wall 26. When the engine is in low-speed revolution, the second exhaust gas passage 28 is closed, and only the first exhaust gas passage 27 is opened. When the engine is in high-speed revolution, the both exhaust gas passages 27 and 28 are opened. At least at the swirl start part of the exhaust gas passages 27 and 28 on the partitioning wall 16 in the turbine casing 21, a tongue part 29 if formed, and in the vicinity of the tongue part 29, a thin part 31 extending in the radial direction of a turbine is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) 7. The present invention relates to an exhaust turbocharger having a plurality of exhaust gas passages in a turbine casing of the exhaust turbocharger.

(Prior art) Generally, in an exhaust turbo supercharger, a single exhaust gas passage is formed inside the turbine casing, and the passage area of the exhaust gas passage is fixedly set, and the exhaust gas passage is fixedly set throughout the entire operating range of the engine. The A/R value determines the turbine efficiency from the viewpoint of obtaining the highest possible level of turbine efficiency (A: passage area of the exhaust gas passage of the turbine casing, R: the passage area of the scroll portion of the turbine casing). radius of curvature) is set according to the amount of exhaust gas when the engine is operated at medium speed.

However, if the A/R value is set in accordance with the medium-speed operation of the engine, the amount of exhaust gas will be higher than the standard exhaust gas amount in the high-speed operation region of the engine. This increases the flow resistance of the exhaust gas, making it impossible to fully utilize the exhaust energy of the exhaust gas.Furthermore, on the engine side, the exhaust pressure increases, causing problems such as deterioration of combustibility and the inability to obtain sufficient engine output. On the other hand, in the low-speed operating range of the engine, the flow rate of exhaust gas decreases as the amount of exhaust gas becomes less than the above-mentioned standard exhaust gas amount, and the turbine wheel cannot rotate sufficiently, resulting in lower turbine efficiency. This will cause the problem of a decline.

Therefore, in order to improve the disadvantages peculiar to an exhaust turbocharger equipped with a turbine casing having a single exhaust gas passage, the exhaust gas passage in the turbine casing is divided into a plurality of sections by partition walls, and the exhaust gas passage is divided into a plurality of sections. By controlling the opening and closing of the exhaust gas passage with a valve device, the passage area of the exhaust gas passage can be made variable according to the operating condition of the engine, thereby ensuring a high level of supercharging performance throughout the entire engine operating range. It is being said.

Alternatively, apart from the above-mentioned point of view, partition walls are formed in the exhaust gas passage to rectify the flow of exhaust gas, and the exhaust gas passage is divided into a plurality of sections.

In a supercharging device in which partition walls are constructed from various viewpoints as described above, as shown in FIG. (hereinafter simply referred to as a tongue) 2, but there is a relatively large temperature difference before and after the tongue 2 (temperature Ta at point A on the upstream side of the exhaust gas and temperature Ta on the downstream side of the exhaust gas). T between the temperature Tb of point B at
(a > Tb), and since the rigidity of this part is significantly different from that of the surrounding casing wall surface, thermal stress is intensively generated in the tongue part 2 and cracks occur in the tongue part 2 or its vicinity. In some cases, the cracks could even reach the outer wall of the turbine casing.

On the other hand, conventionally, as a countermeasure against cracks caused by the temperature difference between the inner and outer circumferential sides of the partition wall, a parting line (slit) of a predetermined length extending in the exhaust gas introduction direction has been installed in a part of the partition wall (exhaust gas inlet part). ) is formed as shown by the symbol S in FIG. 6 above to prevent cracks caused by the temperature difference from extending to the outer wall of the turbine casing (
For example, see Utility Model Application Publication No. 52-133809).

However, in this prior art, as shown in FIG. 6, the dividing line S itself is only formed at the position of the exhaust gas inlet of the turbine casing 3 and facing the flow direction of the exhaust gas. Therefore, it cannot be a measure to prevent cracks occurring at or near the tongue of the turbine casing due to the large temperature difference before and after the tongue as described above.

(Object of the Invention) The present invention has been made in order to improve the above-mentioned drawbacks, and the portion where cracks are likely to occur near the tongue portion is intentionally formed into a slit or a thin wall portion in the radial direction of the turbine. The purpose of this is to relieve the stress at the relevant portion and prevent the occurrence of unexpected cracks that would extend to the outer wall of the turbine casing as described above.

(Means for achieving the object) In order to achieve the above object, the present invention divides the exhaust gas introduction passage in the turbine casing into a plurality of exhaust gas passages by partition walls along the flow direction of the exhaust gas. In the exhaust turbocharging device, the partition wall is provided with a slit or a thin wall portion extending in the radial direction of the turbine at least in the vicinity of the winding start tongue of the exhaust gas introduction passage.

(Function) According to the above means, since the slit or thin walled portion extending in the turbine radial direction is provided near the winding start tongue of the common exhaust gas introduction passage with few partition walls, thermal stress is reduced in the slit or thin walled portion. This prevents stress from accumulating at or near the tongue, thereby avoiding the occurrence of unexpected cracks that extend to the outer wall of the turbine casing.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 4.

1 to 4 show an exhaust turbo supercharging device according to an embodiment of the present invention, and in each of these figures, reference numeral 1O is an engine body, 20 is an exhaust turbo supercharger, The exhaust turbo supercharger 20 is fixed to the exhaust pipe 30 of the engine via a gasket. and,
The exhaust turbo supercharger 20 includes a turbine casing 21 containing a turbine wheel 50 and a compressor casing 2 containing a compressor wheel (not shown).
2 are connected to each other via a center housing 23.

As shown in FIGS. 1 to 3, the turbine casing 21 has a scroll-shaped exhaust gas introduction passage formed therein, and a partition wall 2 extending in the direction of the scroll.
2 aligned in the axial direction of the turbine casing 2I by 6.
A first exhaust gas passage 27 located on one side of the partition 26 and a second exhaust gas passage 27 located on the other side of the partition 26 and having a smaller passage area than the first exhaust gas passage 27. The exhaust gas passage 28 is divided into two left and right exhaust gas passages. These two exhaust gas passages 27 and 28 are
Exhaust gas inlet ports 27a and 28a, both of which are formed of open ends on the upstream side of the exhaust gas, are opened on the end surface of the turbine casing 21 on the upstream side of the exhaust gas, which acts as an abutment surface toward the exhaust pipe 4 side. There is. Of these two exhaust gas introduction ports 27a and 28a, the first exhaust gas introduction port 27a
is kept open throughout the entire operating range of the engine, but the second exhaust gas inlet 28a is closed by a predetermined valve device 38 when the engine is running at low speeds, and is opened when the engine is running at high speeds. There is.

This valve device 38 includes the actuating device 36 as well as the link lever 3.
7 to the first actuator 35;
It is driven by the actuator 35 according to the operating state of the engine. That is, when the engine is operating at low speed, only the first exhaust gas inlet is opened and the exhaust gas from the engine is introduced into the scroll portion side of the turbine casing 2I through the first exhaust gas passage 27.
On the other hand, when the engine is operating at high speed, both the first exhaust gas inlet 27a and the second exhaust gas inlet 28a are opened, and the exhaust gas flows through the first exhaust gas passage 27 and the second exhaust gas passage. 28 from both turbine casings 2
It will be introduced to the scroll section side of No. 1.

The partition wall 26 in the turbine casing 2I
A tongue portion 29 is formed at least at the winding start portion of the exhaust gas passages 27 and 28, as shown in FIG.
A thin wall portion 3 extending in the radial direction of the turbine near the tongue portion 29
1 (see FIG. 4) is formed.

Therefore, during operation of the exhaust turbocharger, even if a large temperature difference occurs before and after the tongue portion 29 in the scroll direction, and thereby excessive thermal stress is generated, the strength of the thin wall portion 31 is the lowest. Thermal stress acting on the tongue portion 29 is absorbed and relaxed by the thin wall portion 31, and as a result, even if a crack occurs in the thin wall portion 31, the crack is limited to the thin wall portion 31. This extends to the outer wall of the turbine casing 21, so that no rack is formed.

The reference numeral 51 indicates a turbine shaft rotatably supporting the turbine rotor within the turbine casing 21, and 52 indicates an exhaust port of the turbine casing 21.

On the other hand, the exhaust pipe 30 is connected to the engine body 1 as shown in FIG.
Four branch pipes 41A, 41B, 41C, 41 are connected to the port 17 facing toward the car at each value open port of 0.
A branch pipe section 41 consisting of D, and each branch pipe 41A, 41B
... are integrally formed with a collecting pipe part 42 extending from the branch pipe part 41 in a direction orthogonal to the branch pipe part 41, while collecting the exhaust gas at the downstream end of the exhaust gas. It is fastened and fixed to the side of the engine main body IO with the end face on the branch pipe side abutting against the engine main body 10 side, and the end face on the collecting pipe part 42 side (i.e., the collecting pipe part 42
The turbine casing 21 of the exhaust turbo supercharger 20 is abutted and fixed to the upper end surface of the exhaust turbo supercharger 20 via a gasket.

Further, in FIG. 3, reference numeral 33 is a wastegate valve having a known structure provided on the side of the turbine casing 21, and the wastegate valve 33 is activated in response to intake pressure (supercharging pressure) of the engine. The opening/closing is controlled by a second actuator 34.

In the above embodiment, the thin wall portion 31 is formed in the vicinity of the tongue portion of the partition wall 26, but it is also possible to form a slit 32 as shown in FIG. 5 in place of the thin wall portion 31. Similar objectives can be achieved. That is, in this case as well, the slit 32 has the effect of absorbing and relaxing the thermal stress in the vicinity of the tongue portion 29, as in the case of forming the thin wall portion 31, so that the generation of a large rack that extends to the outer wall of the turbine casing is prevented. can.

(Effects of the Invention) As explained above, the present invention provides an exhaust turbo supercharging device in which an exhaust gas introduction passage in a turbine casing is divided into a plurality of exhaust gas passages by a partition wall along the flow direction of exhaust gas. A slit or a thin wall portion extending in the radial direction of the turbine is provided in the partition wall at least in the vicinity of the winding start tongue of the exhaust gas introduction passage.

Therefore, according to the present invention, even if a large temperature difference occurs in the vicinity of the tongue portion during operation of the exhaust turbocharger, and thereby excessive thermal stress is generated, the slit or thin wall portion receives the heat. Stress is absorbed and relaxed, and as a result, cracks that are likely to occur near the tongue are prevented from occurring, and even if such a rack occurs, the crack is limited to the slit or thin section. This prevents unexpected cracks from reaching the outer wall of the turbine casing.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of a turbine casing portion of an exhaust turbo supercharging device according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along line ■-n of the turbine casing portion in FIG. Figure 3 is an overall front view of the device, and Figure 4 is
-IV line sectional view, FIG. 5 is a sectional view corresponding to the part shown in FIG. 4 in another embodiment of the present invention, and FIG. 6 is a longitudinal sectional view of the turbine casing part of a conventional exhaust turbocharger. be. 20... Exhaust turbo supercharger 21... Turbine casing 22... Compressor casing 26...
Partition wall 27...First exhaust gas passage 28...Second exhaust gas passage 29...Tongue 30...Exhaust pipe 31...Thin wall portion 32 ...Slit figure 3

Claims (1)

[Claims] 1. In an exhaust turbo supercharging device in which an exhaust gas introduction passage in a turbine casing is divided into a plurality of exhaust gas passages by a partition wall along the flow direction of exhaust gas, at least the winding start of the exhaust gas introduction passage of the partition wall is An exhaust turbo supercharging device characterized in that a slit or a thin wall portion extending in the radial direction of the turbine is provided near the tongue portion.