JPH0536987Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of an exhaust manifold for a V-type engine installed in a vehicle, and is particularly designed to be easy to cast and improve durability under high temperatures. Regarding the structure of the exhaust manifold.

[Prior art] As a prior art related to the present invention, Japanese Patent Application Laid-open No. 1983-
Publication No. 104317 and Japanese Utility Model Application No. 61-9520 are known.

The exhaust path of the V-type engine disclosed in the above-mentioned Japanese Patent Application Laid-open No. 58-104317 is 2
The exhaust manifold has first and second exhaust manifolds that collect exhaust gas from each of the cylinders arranged in a row through a plurality of branch pipes communicating with the cylinders, and the exhaust gas from the first and second exhaust manifolds is combined and discharged. In the exhaust passage of a V-type engine, the first exhaust manifold has a merging branch pipe that merges exhaust gas from the second exhaust manifold, and the second exhaust manifold and the combined flow branch pipe are approximately L-shaped. Connected by a connecting pipe. The connecting pipe is mounted so as to be movable relative to the first and second exhaust manifolds in two substantially orthogonal axial directions of the connecting pipe.

The connection structure between the exhaust manifolds of a V-type engine disclosed in Japanese Utility Model Application Publication No. 1983-9520 consists of a first exhaust manifold and a second exhaust manifold attached to the first bank and the second bank, respectively. The exhaust manifold is connected to the exhaust manifold by a U-shaped exhaust pipe, and the bent portion of the exhaust pipe is formed into a bellows pipe.

Both of the above two publications disclose a connection structure for each exhaust manifold, and are intended to prevent deformation of the exhaust manifold etc. due to heat.

In a transverse V-type engine in which the axis of the crankshaft is arranged at right angles to the longitudinal direction of the vehicle, most of the exhaust manifolds are arranged separated in the longitudinal direction. Cast iron is generally used as a material for the exhaust manifold, as it is relatively easy to cast, is suitable for complex shapes, and is inexpensive, but cast steel may be used depending on the conditions.

[Problems to be solved by the invention] In Europe, there is a demand for a leaner air-fuel ratio than before in order to improve fuel efficiency when driving at high speeds of 150 km/h or more. To achieve this, an exhaust manifold that can withstand exhaust gas temperatures of 900°C or higher is required. This is because, as a result of bringing the air-fuel ratio closer to the stoichiometric air-fuel ratio in order to increase combustion efficiency, the exhaust gas temperature rises more than before.

As mentioned above, cast iron is generally used as a material for exhaust manifolds because it is easy to cast, suitable for complex shapes, and is low cost.
At high temperatures of 850°C or higher, the formation of oxide scale becomes significant, and the disadvantage is that cracks are more likely to occur when the temperature exceeds the reciprocal transformation point.

On the other hand, cast steel has the advantage of being resistant to oxidation even at high temperatures of 900°C, and having a co-reciprocal transformation temperature of 900°C or higher, making it less prone to cracking. It has the disadvantage of being stored away. Therefore, the casting technology is more difficult than that for cast iron, such as the need to flow hot water quickly, and it is difficult to realize it unless the shape is simple.

In this way, when the exhaust manifold is made of cast iron, a problem arises in that it is not possible to simultaneously improve fuel consumption efficiency during high-speed running and improve the durability of the exhaust manifold. Additionally, when cast steel is used as the material for the exhaust manifold, multiple mounting parts are formed on the exhaust manifold, such as the connection with the other bank, the _O2 sensor mounting part, and the turbocharger mounting part, making the exhaust manifold complicated. If the shape is desired, there is a problem in that casting is difficult.

It has been confirmed that under driving conditions of vehicle speeds of 150 km/h or more, if the exhaust manifold is exposed to sufficient wind, the temperature rise in the exhaust manifold can be significantly suppressed due to the cooling effect of the wind.

This invention focuses on the cooling effect of running air when vehicles are running at high speeds, and can improve both castability and durability under high-speed running conditions where the exhaust gas temperature exceeds 900℃. Specifically, it is an object of the present invention to provide an exhaust manifold for a V-type engine that can improve fuel efficiency during high-speed running.

[Means for Solving the Problems] The exhaust manifold for the V-type engine of the present invention that meets this purpose has a first exhaust manifold that is attached to one bank and is easily cooled by the running wind, and is made of cast iron. The first exhaust manifold is formed with a plurality of attachment parts to which various devices are attached, and the second exhaust manifold, which is attached to the other bank and is not easily cooled by the running wind, is made of cast steel.

[Function] In the exhaust manifold of the V-type engine configured as described above, the first exhaust manifold made of cast iron is sufficiently cooled by the running wind while the vehicle is running at high speed, so that the exhaust gas is the temperature of
Even at high temperatures exceeding 900° C., the temperature of the first exhaust manifold can be kept below the co-fractional transformation point temperature.
Therefore, the generation of oxide scale and cracks are prevented, and durability is improved. In addition, cast iron is easy to cast and suitable for complex shapes.
Even if a plurality of attachment parts to which various devices are connected to the first exhaust manifold are formed, there is no problem that manufacturing is difficult as in the case of cast steel.

On the other hand, even if the second exhaust manifold, which is made of cast steel, is placed in a location where it is difficult to cool, the material properties are that the temperature of the co-reciprocal transformation is 900°C or higher, so there is very little oxidation scale formation and no cracking occurs. . Since the second exhaust manifold does not have multiple attachment parts like the first exhaust manifold, it can have a simple shape, making casting extremely difficult even if the flow of hot metal during casting is somewhat poor. It will never become.

[Embodiments] Hereinafter, preferred embodiments of the exhaust manifold for a V-type engine according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention, and show an example in which it is applied to, for example, a six-cylinder V-type engine. In the figure, reference numeral 1 indicates a transverse V-type engine mounted on a vehicle 2, and the V-type engine 1 has a crankshaft (not shown) whose axis is disposed at right angles to the longitudinal direction of the vehicle. V
A first exhaust manifold 4 and a second exhaust manifold 5 are attached to each bank 3a, 3b of the engine 1. The first exhaust manifold 4 and the second
The first exhaust manifold 2 is located in front of the second exhaust manifold 5 so as to be easily cooled by the traveling wind A. ing.

As shown in FIG. 1, openings 6 for exhaust gas passages communicating with each cylinder are formed on the surface of the second exhaust manifold 5 facing the cylinder head 3, and each opening 6 is formed on the side. An outflow portion 7 is formed to collectively exhaust the exhaust gases that have flowed in from the exhaust gas. A plurality of bolt insertion portions 8 for fixing the second exhaust manifold 5 to the cylinder head 3 are formed on the outer circumference of the second exhaust manifold 5 .

Openings 9 for exhaust gas passages communicating with each cylinder are formed on the surface of the first exhaust manifold 4 facing the cylinder head 3, and one exhaust gas passage flowing through each opening 9 is formed in the lower part of the first exhaust manifold 4. An outflow portion 10 is formed to collectively exhaust the air. A plurality of bolt insertion portions 11 for fixing the first exhaust manifold 4 to the cylinder head 3 are formed on the outer circumference of the first exhaust manifold. Immediately upstream of the outflow section 10 of the first exhaust manifold 4, an inflow section 12 is formed that allows exhaust gas flowing out from the second exhaust manifold 5 to flow into the first exhaust manifold 4. That is, the outflow section 7 of the second exhaust manifold 5 and the inflow section 12 of the first exhaust manifold 4 are as follows.
The first exhaust manifold 4 and the second exhaust manifold 5 are connected via a connecting pipe 13 . An O ₂ sensor attachment portion 15 to which an O ₂ sensor 14 is attached is formed near the inflow portion 12 of the first exhaust manifold 4 .

An outflow portion 10 of the first exhaust manifold 4 is connected to an exhaust pipe 16 extending rearward. exhaust pipe 16
A catalyst 17 for purifying exhaust gas is interposed in the middle, and a muffler 18 is disposed downstream of the catalyst 17. Note that the first exhaust manifold 4 is
For example, it may be configured to form a flange for attaching a supercharger.

The first exhaust manifold 4 is made of cast iron (for example, JIS G5501), which is easy to cast and has temperature characteristics such that the temperature at the co-fractional transformation point is 850°C. In other words, the first exhaust manifold 4, which is sufficiently exposed to the running wind and has complex shape factors such as the outflow section 10, inflow section 12, and _O2 sensor mounting section 15, is made of cast iron, which has low thermal strain and is easy to cast. It is used.

The second exhaust manifold 5 is made of cast steel (for example, JIS G5101) that is resistant to oxidation and does not cause cracks at high temperatures exceeding 900°C. In other words, the material for the second exhaust manifold 5, which is less likely to be cooled by the running wind and has a simpler shape than the first exhaust manifold 4, has a reciprocal transformation point temperature of 900°C.
Cast steel is used, which has the above temperature characteristics and is inferior in castability to cast iron.

Next, the operation in the first embodiment will be explained.

When the vehicle travels at a high speed of 150 km/h or more, the temperature of the first exhaust manifold 4 is lowered by nearly 100° C. than the temperature of the exhaust gas discharged from each cylinder due to the cooling effect of the traveling wind A. In other words, the exhaust gas temperature when combustion efficiency is ensured during high-speed driving is
The surface temperature of the first exhaust manifold 4 on the front side, which is sufficiently exposed to the running wind A, reaches 900℃.
It can only reach temperatures of 800 degrees Celsius, making it less likely to oxidize even cast iron, which is inferior in terms of heat, making it more durable.

On the other hand, the second exhaust manifold 5 is hardly exposed to the traveling wind and has almost no cooling effect, but since the second exhaust manifold 5 is made of cast steel, it is less susceptible to oxidation and cracking. In other words, the heat resistance of the second exhaust manifold 5 is ensured by the characteristics of the material itself, regardless of the running wind A. Unlike the first exhaust manifold 4, the second exhaust manifold 5 does not have an inflow part 12 or an O ₂ sensor mounting part 15, so the overall shape is simplified and the flow of hot water is lower than that of cast steel. However, casting is relatively easy.

In this way, by effectively utilizing the cooling effect of running air and the advantages of cast iron and cast steel, various problems can be compensated for and an exhaust manifold that can withstand high temperatures of over 900°C can be obtained. .

Second Embodiment FIG. 3 shows a second embodiment of the present invention.
The second embodiment differs from the first embodiment in the arrangement direction of the V-type engine, and the other configurations differ from the first embodiment.
Since this embodiment is similar to the first embodiment, the same reference numerals as in the first embodiment are given to the corresponding parts, and the explanation of the corresponding parts will be omitted, and only the different parts will be explained.

In FIG. 3, reference numeral 21 indicates a vertically installed V-type engine mounted on the vehicle 2, and the vertically installed V-type engine 21 is arranged such that the axis of a crankshaft (not shown) is along the longitudinal direction of the vehicle. There is. A first exhaust manifold 24 and a second exhaust manifold 25 are attached to the V-type engine 21.
The first exhaust manifold 24 and the second exhaust manifold 25 are arranged to be separated from each other in the left-right direction of the vehicle. Among these, the first exhaust manifold 24 is arranged at a position where it is sufficiently cooled by the traveling wind A. In front of the second exhaust manifold 25,
Due to storage space, air conditioner pump 26,
A power steering pump 27, a supercharger 28, etc. are arranged, and the second exhaust manifold 24 is prevented from being hit by the traveling wind A.

First exhaust manifold 2 that is well exposed to the driving wind A
4 is made of cast iron, and the second exhaust manifold 25, which is not easily exposed to the traveling wind A, is made of cast steel. The first exhaust manifold 24 is formed with a plurality of attachment parts (not shown) to which various devices are connected, as in the first embodiment, and the second exhaust manifold 24 is provided with a plurality of attachment parts (not shown) to which various devices are connected.
5 is simplified compared to the shape of the first exhaust manifold 24.

In the second embodiment configured in this way,
When the vehicle is running at high speed, the first exhaust manifold 2
Since No. 4 is cooled by the wind while running, cracks do not occur beyond the point of reciprocal transformation, and durability is improved even in cast iron. Furthermore, due to the arrangement of the supercharger, etc., the second exhaust manifold 25 is less likely to be exposed to running air, reducing the cooling effect; however, since the second exhaust manifold 25 is made of cast steel, the temperature of the exhaust gas Its durability is fully guaranteed even when the temperature exceeds 900℃. Other operations are similar to those in the first embodiment.

[Effect of the invention] As explained above, when using the exhaust manifold of the V-type engine of the invention, the first exhaust manifold that is easily cooled by the running wind is made of cast iron, and the first exhaust manifold is made of cast iron. The second exhaust manifold, which has multiple mounting parts to which various devices can be attached, and is difficult to be cooled by the running wind, is made of cast steel, so that the cooling effect of the running wind and the advantages of cast iron and cast steel are achieved. By making effective use of this, it is possible to both improve the castability of the exhaust manifold in a V-type engine and improve its durability under high temperatures.

In addition, by adopting an exhaust manifold that is resistant to high temperatures, it is possible to raise the exhaust gas temperature to the 150 km/h required in the European market.
The fuel efficiency during high-speed driving can be improved as described above.

Furthermore, since the first exhaust manifold, which has a plurality of attachment parts to which each device is attached, is made of inexpensive cast iron, the cost is lower than when both exhaust manifolds are made of cast steel. As the first exhaust manifold has become more complex, the shape of the second exhaust manifold made of cast steel has been simplified, making it possible to improve the marketability of the second exhaust manifold, which was difficult to cast. can.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the vicinity of the exhaust manifold of a V-type engine according to the first embodiment of the present invention, and FIG.
FIG. 3 is a schematic plan view of the vicinity of the exhaust manifold of a V-type engine according to a second embodiment of the present invention. 1...Horizontal V-type engine, 2...Vehicle, 4,2
4...First exhaust manifold, 5,25...Second
Exhaust manifold, 10...outflow section, 12...inflow section, 13...connection pipe, 15... _O2 sensor mounting section, 21...vertical V-type engine, A...driving wind.

Claims (1)

[Scope of utility model registration request] A first exhaust manifold that is attached to one bank and is easily cooled by the running wind is made of cast iron, and a plurality of attachment parts to which various devices are attached are formed on the first exhaust manifold, and the first exhaust manifold is attached to the other bank. An exhaust manifold for a V-type engine, characterized in that a second exhaust manifold, which is not easily cooled by running wind, is made of cast steel.