JPH07139364A - Turbo-charger - Google Patents

Abstract

PURPOSE:To provide a turbo-charger with no drop in temperature of an exhaust gas on a turbine side and less heat absorption. CONSTITUTION:A turbo-charger 1 forms an outer shell 21 of a turbine housing 12 containing an exhaust gas intake passage 8, and has an inner shell 22 having a specified insulating layer 14 formed on the inner wall of the outer shell 21, formed with a thin heat-resistant steel plate 13, and for passing through an exhaust gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger mounted on an automobile or the like, and more particularly to a turbocharger aiming at early activation of a catalyst by reducing heat absorption from exhaust gas.

[0002]

2. Description of the Related Art At present, there are many examples in which a turbocharger is installed to improve the engine output of an automobile or the like.

As shown in FIG. 3, the turbocharger 1
Has a turbine wheel 4 and a compressor wheel 5 respectively attached to both ends of a turbine shaft 3 which is rotatably attached to the center housing 2, and connects a turbine housing 6 and a compressor housing 7, which accommodate them, to the center housing 2. And is mainly composed. On the turbine wheel 4, a plurality of moving blades (turbine blades) 4a are arranged in a row at equal intervals in the circumferential direction. An exhaust gas introduction passage 8 for introducing exhaust gas from the engine to the turbine wheel 4 is formed in the turbine housing 6. The exhaust gas introduction passage 8 is connected to the turbine shaft 3
Is formed in a spiral shape or a scroll shape that is perpendicular to the axial direction of and along the moving blades 4a of the turbine wheel 4, and the cross-sectional area thereof is gradually reduced along the exhaust gas flow direction. The exhaust gas that has entered from the inlet 8a of the exhaust gas introduction passage 8 is introduced into the moving blade 4a of the turbine wheel 4 from the front (on the right side in the figure), and after driving the turbine wheel 4 to rotate, it passes behind the moving blade 4a as it is. Exhausted from the exhaust gas outlet 9. A turbine of the type in which the exhaust gas passes through the moving blades 4a in the axial direction in this way is well known as an axial flow (axial) turbine. In addition, a nozzle for guiding the exhaust gas to the moving blade 4a may be provided in front of the moving blade 4a in the exhaust gas introduction passage 8.

As can be seen from the figure, the exhaust gas introducing passage 8 and the exhaust gas outlet 9 are formed by casting the turbine housing 6, and since the turbine housing 6 is directly exposed to the high temperature of the exhaust gas, thermal deformation and oxidation resistance. In consideration of the workability and the workability such as casting and cutting, for example, a special heat resistant casting is used to form a relatively thick wall.

[0005]

As described above, since the turbine housing 6 is thick and has a relatively large heat capacity, and the turbine housing 6 is in direct contact with high-temperature exhaust gas, the following problems occur.

[0006] Normally, a catalyst is provided on the turbine downstream side of the turbocharger 1. However, the catalyst does not reach the activation temperature immediately after the engine start (cold start) in the cold state, while the exhaust gas is the turbine housing. 6 is absorbed by heat and cooled, so that the period until activation of the catalyst becomes long, which causes deterioration of cold emission.

The thermal energy of the exhaust gas is taken by the turbine housing 6, and is not effectively utilized as the rotational energy of the turbine wheel 4, resulting in a reduction in performance.

Since special heat-resistant castings are often used in manufacturing the turbine housing 6, it is expensive.

Therefore, the present invention was devised to solve the above problems, and an object thereof is to provide a turbocharger that does not lower the temperature of exhaust gas on the turbine side and that absorbs less heat.

[0010]

In order to achieve the above object, a turbocharger according to the present invention forms an outer shell of a turbine housing including an exhaust gas introduction passage, and forms a predetermined heat insulating layer on the inner wall of the outer shell. It is made of a thin heat-resistant steel plate and is provided with an inner shell through which exhaust gas passes.

[0011]

According to the above construction, since the inner shell through which the exhaust gas passes has a small heat capacity, it is heated to a high temperature early by receiving heat from the exhaust gas, and on the other hand, it is insulated so that the heat is not transferred to the outer shell. Therefore, the thermal energy of the exhaust gas can be effectively used.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing such a turbocharger 1. The turbocharger 1 has an axial flow type turbine 10 as in the conventional example. The turbine 10 mainly includes a turbine housing 12 connected to the center housing 2 via an engaging member 11, a turbine wheel 4 similar to a conventional one, and an exhaust gas introduction passage 8 for introducing exhaust gas from an engine to the turbine wheel 4. Composed.

In particular, the turbine housing 12 is separated from the outside by an outer shell 21 formed of a metal material such as cast iron.
An inner shell 22 formed of the thin heat-resistant steel plate 13 is provided inside the outer shell 21. The inner shell 22 substantially defines the exhaust gas introduction passage 8.

As the thin heat-resistant steel plate 13, for example, Hastelloy, Inconel, SUS material or the like is adopted, and the plate thickness thereof is about 0.5 to 1 mm at which press working is possible. After this is molded into components described in detail later, they are joined to form the inner shell 22. The inner shell 22 receives the exhaust gas sent from the exhaust manifold 15 from the supply portion 8c via the inlet portion 8b and the moving blades 4a of the turbine wheel 4.
It is designed to be supplied to.

The inlet portion 8b is the press-formed inlet member 8
The extended end portion 8i is sandwiched between the outer shell 21 and the exhaust manifold 15. The supply unit 8c includes a rear member 8d and a front member 8e obtained by press working.
The inner peripheral side is joined by bending the end portion of the front member 8e along the flange portion 8f of the rear member 8d, and the locking pieces 8g of each other are overlapped to form the outer shell 21 and the exhaust pipe 16. By being sandwiched, the outer peripheral side is joined and supported.
Then, the inlet member 8h is inserted and joined to the rear member 8d. In the illustrated example, the space portion 1 is provided on the outer peripheral side of the supply portion 8c.
Although No. 7 is formed, a structure without this may be used. Further, the front member 8e has a nozzle 18 integrally bent on a surface along the turbine wheel 4, and the surface along the tip of the moving blade 4a is axially extended to serve as a shroud 19. Plays a function. As shown in detail in FIG. 2, the plurality of nozzles 18 are formed in the circumferential direction.

The inner shell 22 thus formed has the extending end 8i of the inlet member 8h, the rear member 8d and the front member 8e.
Is supported by being connected to the outer shell 21 only, and the other portions are separated from the center housing 2, the outer shell 21 and the turbine wheel 4 by a predetermined distance. The space is hollow to form an air layer 20 as the heat insulating layer 14.

Next, the operation of the embodiment will be described.

At the cold start of the engine,
The high-temperature exhaust gas sent from the exhaust manifold 15 is introduced into the turbine wheel 4 through the inner shell 22. Since the inner shell 22 is made of the thin heat-resistant steel plate 13 and has a small heat capacity, the inner shell 22 quickly becomes high temperature by receiving heat from the exhaust gas. Further, most of the inner shell 22 is thermally insulated by the heat insulating layer 14 or the air layer 20, so that the heat transfer to the outer shell 21 is minimized, and therefore, it is maintained in that state after the temperature becomes high. . Conversely, the outer shell 21 does not absorb heat and does not reach such a high temperature.

As a result, the heat energy of the high-temperature exhaust gas is not taken away, cooling is suppressed, the catalyst can be quickly reached the activation temperature, and cold emission can be improved. In addition, the heat energy is transferred to the turbine wheel 4
It can be effectively utilized as the rotational energy of, and the performance can be improved.

Further, since the outer shell 21 is not directly exposed to the high temperature of the exhaust gas, it is possible to replace what was conventionally manufactured by using a special heat resistant casting with cast iron or the like having poor heat resistance.
Manufacturing cost can be reduced by lowering the grade of such a material. In addition, since the temperature does not rise as compared with the conventional one, the oxidation resistance is also improved. The inner shell 22 can be easily manufactured by press working, and at that time, the nozzle 18 and the shroud 19 can be integrally molded, so that the manufacturing process can be shortened. Then, the structure is simplified by separating the inner shell 22 from the outer shell 21 and forming the heat insulating layer 14 by the air layer 20 as described above. The heat insulating layer 14 may be formed of a heat insulating material that can withstand the highest temperature, such as ceramics. The inner shell 22 is supported by sandwiching the extending end portion 8i and the locking piece 8g, so that the turbocharger 1 is supported at the same time when it is connected to the exhaust manifold 15 and the exhaust pipe 16, so that the assembly is easy. .

In the above embodiment, only the case of the axial flow turbine is shown, but the same structure can be applied to the radial turbine. Further, the shape and the supporting method of the inner shell 22 can be variously modified other than the above.

[0023]

The present invention exhibits the following excellent effects.

(1) The catalyst can be activated early and the cold emission can be improved.

(2) The thermal energy of the exhaust gas can be effectively used and the performance is improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a turbocharger according to the present invention.

FIG. 2 is a view taken along the line AA of FIG.

FIG. 3 is a side sectional view showing a conventional turbocharger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbocharger 8 Exhaust gas introduction passage 12 Turbine housing 13 Thin heat-resistant steel plate 14 Thermal insulation layer 21 Outer shell 22 Inner shell

Claims (3)

[Claims] 1. An outer shell of a turbine housing including an exhaust gas introducing passage is formed, and a predetermined heat insulating layer is formed on an inner wall of the outer shell, and the inner shell is made of a thin heat-resistant steel plate and allows exhaust gas to pass therethrough. Is a turbocharger. 2. The outer shell of the turbine housing is formed of a material such as cast iron, and the inner shell of the turbine housing is
The turbocharger according to claim 1, which is formed of a heat-resistant steel plate such as Hastelloy, Inconel, or SUS material. 3. The turbocharger according to claim 1, wherein the heat insulating layer is formed by a hollow heat insulating layer with a predetermined space between the outer shell and the inner shell.