JPH0230926A - Exhaust gas bypass device for exhaust gas turbine type turbocharger - Google Patents

Abstract

PURPOSE:To absorb heat deformation among respective constructive ports so as to aim at the prevention of sticking among the respective constructive parts, and so on by setting a predetermined initial gap between a bearing member for holding the rotary motion of a stay member and the inserting hole of the bearing member in a housing. CONSTITUTION:A bearing member 3 is housed in the inserting hole 2 of a turbine housing 1 and the flange portion 31 of its one end is fixed to a boss portion 11 with partial welding 4. The rotary shaft portion 61 of a stay member 6 for holding a valve member 5 for exhaust bypass is housed in the inner diameter portion 32 of the bearing member 3. Further, a link member 7 for transmitting the motion of pressure device is arranged at the outer wall 62 of the end of the stay member 6. In this construction, a predetermined initial gap d4-d3 is set between the inserting hole 2 and the outer diameter portion 33 of the bearing member 3. And heat deformation among respective constructive parts 1, 3 is absorbed by the initial gap. d4-d3.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an exhaust turbine type supercharger that is rotationally driven by receiving exhaust gas from an internal combustion engine, and in particular, the stay member is used in an internal combustion engine with high-temperature exhaust gas specification. The present invention relates to an exhaust bypass device that is suitable for obtaining high reliability without sticking or the like.

[Conventional technology]

Even in the conventional device, the basic structure of the exhaust bypass device is the same as described in Utility Application No. 1987-1.94469, but the bearing member that supports the rotational movement of the stay member is an insert provided in the turbine housing. The flange was fixed by press-fitting into the hole, or by welding after press-fitting.

Furthermore, conventional bearing members have generally been made of sintered material.

[Problem to be solved by the invention]

In the above conventional technology, the bearing member is press-fitted into the turbine housing, so no consideration is given to maintaining the shape of the bearing member against thermal deformation caused by high-temperature exhaust gas flowing through the internal passage of the turbine housing. Thermal deformation of the insertion hole provided in the turbine housing is directly transmitted to the bearing member, the bearing member is tightened and the inner diameter is reduced, and the rotating shaft of the stay member supported by the inner diameter of the bearing member is fixed, and the exhaust bypass function is activated. There was a problem of losing it.

An object of the present invention is to significantly reduce the reduction in the inner diameter of the bearing member by preventing the thermal deformation of the bearing member insertion hole provided in the turbine housing from being transmitted to the bearing member. The purpose is to prevent members from sticking together.

[Means to solve the problem]

In order to achieve the above object, in the present invention, after providing an appropriate initial gap between the bearing member insertion hole provided in the turbine housing and the outer diameter of the bearing member to be inserted, the pressure device is actuated on the stay member of the bearing member. The link member side flange portion, which transmits rotational motion, is welded and fixed to the outer wall of the turbine housing.

In other words, this initial gap absorbs thermal deformation of the insertion hole provided in the turbine housing.

In addition to the sintered material used in conventional technology, the bearing member of the present invention is made of cut steel or cast material, thereby improving the deformation prevention effect of the bearing member itself and achieving the above objective. It is more effective against

[Effect]

A turbine housing, which has a high-temperature exhaust gas passage inside, causes local temperature differences due to differences in the wall thickness of each part and differences in cooling conditions from the outside, causing thermal strain, and each part repeatedly undergoes minute deformation. Therefore, the bearing member insertion hole provided in the turbine housing also begins to deform in a direction in which the inner diameter thereof is reduced. Further, the bearing member disposed in the insertion hole is also deformed due to the similar influence of the high-temperature exhaust gas.

The magnitude of these deformations is determined by the materials used for the turbine housing and bearing members, and further by the exhaust gas temperature given as the environmental temperature.

Here, bearing members are generally made of a material with better heat resistance than the turbine housing, and the parts that most affect the fixation of the rotating shaft of the stay member mentioned above, that is,
The part that undergoes the largest thermal deformation is the bearing member insertion hole of the turbine housing. Furthermore, this thermal deformation tends to become saturated over time. Therefore, in contrast to the conventional press-fitting method, where the reduction of the insertion hole directly leads to tightening of the bearing member,
In the present invention, an initial gap is provided between the insertion hole and the outer diameter of the bearing member, so that the bearing member is not tightened.

Further, depending on the material of the bearing member, thermal deformation of the bearing member itself varies greatly. For example, in the case of a sintered material having a relatively coarse structure, the thermal deformation of the bearing member itself is extremely large compared to a steel material made of the same material or a member made by cutting a cast material.

Therefore, the selection of materials based on the usage environmental conditions can also be an important effect.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.4 Figure 1(a) shows an exhaust bypass device showing one embodiment of the present invention, and shows a partial cross-section centered around the bearing member. 1. A bearing member; 3 is housed in the insertion hole 2 of the turbine housing 1, and a flange portion 318 at one end of the bearing member;
is fixed to the outer wall of the turbine housing boss portion 11 by partial welding 4. A rotary shaft portion 61 of a stay member 6 that integrally supports a valve member 5 for performing exhaust bypass is housed in the inner diameter portion 32 of the bearing member ’3, and the outer wall side 62 of the end portion is provided with a pressure The turbine housing 1 is located below the valve member 5, which is integrally supported by the stem member 6, in which a link member 7 for applying the operation of the device 21 to the stay member 6 as a rotational motion is provided.
As shown in FIG. 2B, a bypass hole 13 is provided to communicate with the gas passage 12 in the turbine housing 1 and to allow gas to flow to the outside bypassing the turbine impeller.

In other words, the operation of the pressure device 21, which will be described later, is performed by the rod member 22.
The signal is transmitted to the link member 7 by the link member 7. The link member 7 rotates around the rotating shaft portion 61 of the stem member 6 housed in the bearing member 3.

The valve member 5 integrally supported by the stay member 6 opens and closes the bypass hole 13 described above.

Such an exhaust bypass device is often constructed integrally with a turbine housing 1 of an exhaust turbine supercharger, the side view of which is shown in FIG. Exhaust gas discharged from the internal combustion engine is guided into a gas passage formed inside the turbine housing 1, and rotationally drives a turbine impeller disposed at the center thereof. A compressor impeller is disposed at the other end of the shaft that is integrated with the turbine impeller, and compressed air is generated in the scroll passage of the compressor housing 23 formed on the outer periphery of the compressor impeller and pumped into the engine cylinder. are doing.

On the other hand, a pressure device 21 having a rod member 22 that responds to the pressure of the intake system of the internal combustion engine from the compressor housing 23 is disposed on the outside of both housings.
When the pressure exceeds the required pressure value, the rod member 22 operates in the lower right direction in FIG. 2, and the stay member 6 rotates in the direction in which the valve member 5 opens the bypass hole 13 in FIG. 1(b).

In the structure and operation described above, high temperature gas at a maximum temperature of around 1000° C. is introduced into the gas passage 12 within the turbine housing 1. Therefore, each member constituting the 5 exhaust bypass device is in a high temperature state close to the gas temperature. In general, these components, such as a turbine housing 1, a bearing member 3,
Among the stay members 6 (the same applies to the rotating shaft portion 61), the turbine housing 1 is made of the material with the lowest heat resistance. Thermal deformation of each member will be considered under these conditions.

FIG. 3 shows the amount of deformation of each member in three cases as an example when using environmental conditions and time are variables.

- The symbols for each of the three examples a, b, and c surrounded by a dotted chain line are
- The mark is the bearing member inner diameter dz, the square mark is the bearing member outer diameter d3, and the mark is the rotating shaft outer diameter d1. The O mark indicates the amount of deformation of the insertion hole inner diameter d4.・The deformation of the inner diameter d+ of the turbine housing insertion hole indicated by the O symbol is several times larger than that of the 1m mark.

(The operating environment temperature or time is severe in the order of c, b, and a) In other words, the fixation problem of the rotating shaft that occurred between the rotating shaft portion 61 of the stay member 6 and the inner diameter portion 32 of the bearing member 3 is caused by
In the conventional structure, the outer diameter part 33 of the bearing member 3 is press-fitted into the insertion hole 2 of the turbine housing 1, so the insertion hole 2 shrinks due to thermal deformation of the housing part, and the bearing member 3 is tightened, causing the inner diameter part 32 to shrink. Eventually, a sticking phenomenon occurred between the rotary shaft portion 61 and the rotary shaft portion 61.

In the present invention, we grasp the thermal deformation of each component phase over time under various temperature conditions, focus on the insertion hole 2 with the largest amount of deformation, and as shown in FIG. Focusing on the fact that deformation saturates to a certain amount over time, in order to prevent this amount of deformation from being transmitted to the bearing member 3, an initial gap d< d3 was considered between the insertion hole 2 and the outer diameter portion 33 of the bearing member 3. It is something. By employing this structure, it is possible to prevent the rotating shaft portion 61 of the stay member 6 from sticking to the bearing member 3.

In addition, setting the initial gaps d4 to d3 to be larger than necessary causes a large amount of exhaust gas to flow into the gap, which promotes the formation of oxide scale on the surfaces of the two members. Since there is a concern that gas may leak from the gap 34, it is necessary to select an appropriate value.

FIG. 4 shows, as an example, variations of the inner diameter d4 of the turbine housing bearing member insertion hole depending on three types of materials. Characteristic 41 is general spheroidal graphitized cast iron, characteristic 42 is 20
Spheroidal graphitized cast iron with ~35% Ni added, property 43 is 2
Experimental results using ONi-25Cr% cast steel are shown. All of them were left at a high temperature around 1000°C, but the amount of deformation varies greatly depending on the material. Generally, the selection of such materials depends on the maximum temperature of the exhaust gas discharged from the internal combustion engine, but considering the tightening of the outer diameter portion 33 of the bearing member 3 due to the deformation of the insertion hole 2,
In characteristic 41, the above-mentioned initial gap d4-da is 50
While approximately 0μ is required, for characteristic 43, the equivalent value only needs to be approximately 50μ. Therefore, it is important to select an appropriate value for the initial gap d4-da depending on the environmental conditions and the material used.

FIG. 5 shows five examples of deformation of the bearing member 3 by material. In the above, prevention of sticking has been discussed while ignoring the deformation of the bearing member 3. However, thermal deformation (including high-temperature oxidation) of the bearing member 3 itself is not uncommon, and depending on the material, deformation to the extent that promotes the sticking phenomenon is highly conceivable. Characteristics 51 and 52 represent variations of sintered materials commonly used under the prior art. Characteristics 53 and 54 are deformations of cut products machined from steel whose material composition is almost the same as the sintered material, and characteristic 55 is 6ON.
It shows the deformation of the cut product machined from the heat-resistant cast steel of i. Therefore, even if the components are the same, their deformation state will vary greatly depending on the manufacturing method, so the initial gap d4-d
When setting a, it is necessary to give sufficient consideration to the material of the bearing member 3, and it is more advantageous to use a machined product made of general steel or cast steel than a sintered material with a relatively coarse structure. It can be said that there is.

Although the exhaust bypass device has been described above, it is also applicable to a flow path switching device for a supercharger that controls the rotation of a turbine by arbitrarily switching a plurality of gas flow paths.

FIG. 6 shows an embodiment of a flow path switching type variable displacement turbo. The turbine housing 1 is provided with a primary gas passage 71 and a secondary gas passage 72, and has a function of opening and closing the secondary gas passage 72 by a flow path switching device 73. With this function, when the amount of exhaust gas discharged from the engine is small, the flow path switching device 73 is closed and the exhaust gas is introduced only into the primary gas passage.
The exhaust gas flows into the turbine impeller at a high gas flow rate to enhance the supercharging effect, and when the amount of exhaust gas is large, the flow path switching device 7
3 is opened to introduce exhaust gas into the secondary gas passage to lower exhaust pressure and increase turbine efficiency.

A swing valve type is mainly used for the flow path switching device 73, which has a valve body 74, a stay member 75, and a rotating shaft 76 like the exhaust bypass device, and the rotating shaft 61 of the exhaust bypass device is located at the turbine outlet. In contrast, the rotating shaft 76 of the flow path switching valve is installed at the turbine inlet, and the operating environment is lower than the exhaust bypass device because the exhaust gas temperature is high at the turbine inlet. It's even more severe than before. Therefore, by applying the present invention to this flow path switching valve device 73, the rotating shaft 7
6 can be prevented from sticking.

〔Effect of the invention〕

As described above, according to the present invention, there is an appropriate initial gap d between the insertion hole diameter of the housing member that undergoes the largest thermal deformation and which leads to the tightening of the outer diameter of the bearing member to be inserted and the outer diameter of the bearing member.
By providing 4-d3, thermal deformation over time can be absorbed into this initial gap, and the stay member rotating shaft portion is fixed to the inner diameter of the bearing member for opening and closing the exhaust bypass valve. This makes it possible to prevent malfunctions such as engine damage due to an abnormal increase in boost pressure.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are partial sectional views of an exhaust bypass device showing an embodiment of the present invention, and FIG. 2 is a partial sectional view of an exhaust turbine supercharger to which the prior art and the embodiment of the present invention are applied. The external view, Figure 3 shows the deformation of each member by various experiments, Figure 4 shows the deformation of the turbine housing insertion hole by material, and Figure 5 shows the deformation of the bearing member by material. FIG. 6 shows a configuration diagram of a flow path switching device according to another embodiment. 1... Turbine housing, 2... Insertion hole, 3...
・Bearing member, 31...Flange part, 32...Inner diameter part, 33...Outer diameter part, 4...Partial welding, 6...Stay member, 61...Rotating shaft part, 12...・・Gas passage, 1
3... Bypass hole, 5... Valve member, dl... Rotating shaft outer diameter, dl... Bearing member inner diameter, da... Bearing member outer diameter, da... Insertion hole inner diameter, 71. ...Secondary gas passage, 72...Secondary gas passage, 73 Funeral map Figure 4 (H) Figure Nazutan Haruma (Hr) Figure 6

Claims (1)

[Scope of Claims] 1. A bypass hole that communicates with the turbine housing gas passage and is provided to allow gas to flow to the outside bypassing the turbine impeller, and a valve member for opening and closing the hole, holding the valve member;
In an exhaust bypass device for an exhaust turbine type supercharger, the stay member includes a stay member that rotates the inner diameter portion of the bearing member fixed to the housing, and a link member that applies the operation of the pressure device to the stay member as a rotational motion. An exhaust bypass device for an exhaust turbine supercharger, characterized in that a bearing member that supports rotational movement of the member is supported and fixed with an initial gap provided to an insertion hole of a housing provided for inserting the bearing member. . 2. An exhaust turbine type according to claim 1, characterized in that the gap formed by the inner diameter of the insertion hole of the turbine housing and the outer diameter of the bearing member is in the range of 0.05 mm to 0.50 mm. Turbocharger exhaust bypass device. 3. An exhaust turbine supercharger comprising a bearing member having a relatively thin cylindrical portion configured by providing an initial gap between the inner diameter of an insertion hole provided in the turbine housing and the outer diameter of the bearing member. Exhaust bypass device. 4. An exhaust bypass device for an exhaust turbine supercharger according to claim 1, characterized in that the bearing member and the turbine housing are supported and fixed by partial welding. 5. An exhaust gas flow switching device characterized by having a bearing member supported and fixed with an initial gap provided between the insertion hole diameter of the bearing member and the outer diameter of the bearing member. 6. An exhaust bypass device for an exhaust turbine supercharger, comprising a bearing member having a relatively thin cylindrical portion formed by cutting a steel material. 7. An exhaust bypass device for an exhaust turbine supercharger, comprising a bearing member having a relatively thin cylindrical portion formed by cutting a cast material.