JP2567447Y2 - Engine exhaust system - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an engine, and more particularly to an exhaust system in which an exhaust manifold is formed of a steel pipe.

[0002]

2. Description of the Related Art Conventionally, as an exhaust device of an engine,
For example, as disclosed in Japanese Utility Model Laid-Open Publication No. 2-94319, there is known an exhaust passage arranged so as to extend from the side of the engine to the rear of the vehicle body across the lower part of the engine. Further, as disclosed in Japanese Utility Model Laid-Open Publication No. 2-94317, there is also known an exhaust passage in which an exhaust passage extends from the side of the engine to the rear of the vehicle body across below the engine, and a catalyst is disposed downstream of the exhaust passage. .

[0003] By the way, in an engine mounted horizontally on a vehicle body, an exhaust passage is usually provided to prevent heat from the exhaust passage from being trapped in the engine room and affecting the engine room by heat damage. It extends from the side of the engine on the front side of the vehicle body to the rear of the vehicle body across the lower part of the engine. Also, regarding the catalyst provided in the exhaust passage, in order to effectively use the space in the engine room and to prevent heat damage to the engine room, the exhaust passage below the floor of the crew compartment behind the engine room. Some are arranged on the downstream side. Some exhaust manifolds are formed of steel pipes in order to reduce the weight of the exhaust passage.

[0004]

However, as described above, the exhaust passage is arranged so as to extend from the side of the engine to the rear of the vehicle body from below the engine to the rear of the vehicle body, and the catalyst is disposed under the floor of the crew room behind the engine room. In the layout in which the catalyst is disposed on the downstream side of the exhaust passage, the catalyst is considerably separated from the engine, so that the exhaust gas may be cooled in the exhaust passage on the way and the catalyst may not be sufficiently activated. In particular, when the exhaust manifold is formed of a steel pipe, the heat dissipation is higher than in the case of a cast exhaust manifold, and the tendency is increased. For this purpose, the exhaust manifold is surrounded by an insulator or the like to keep the temperature warm.However, a flange provided for connecting the exhaust manifold and the exhaust pipe on the downstream side of the exhaust manifold with good assemblability is usually an obstacle. And the insulation effect of the insulator cannot be sufficiently exhibited, and
Heat is also considerably dissipated from this flange, which hinders the promotion of catalyst activation.

[0005] The present invention has been made in view of such a point, and an object of the present invention is to effectively use an exhaust system of an engine mounted horizontally on a vehicle body in an engine room. In addition, it is necessary to arrange them appropriately so as not to impair the assemblability and the promotion of catalyst activation.

[0006]

Means for Solving the Problems In order to achieve the above object, a solution taken by the invention of claim 1 is that the engine is mounted laterally on the vehicle body with the crankshaft arranged in the vehicle width direction. The exhaust passage extends from the front side of the body of the engine to the rear of the vehicle across the lower side of the engine, and a catalyst is arranged in the exhaust passage on the rear side of the engine of the engine. The exhaust port for each cylinder of the engine is provided. It is assumed that the exhaust manifold upstream of the exhaust passage connected to the exhaust passage is formed of a steel pipe. A collecting portion for connecting the exhaust manifold and an exhaust pipe forming a common passage downstream of the exhaust passage is formed of a steel pipe, and the collecting portion is arranged on a front side of the vehicle body of the engine, and a pipe wall of the collecting portion is formed. Are directly connected to the pipe wall of the exhaust manifold and the pipe wall of the exhaust pipe, respectively, and are connected to the exhaust pipe of the common passage upstream of the catalyst and the collecting section by a support portion fixed to the engine body side. The exhaust pipe downstream of the position is supported so as to be movable in the axial direction of the exhaust pipe passage.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, an insulator surrounding the exhaust passage upstream to the collecting portion is provided. Further, in the invention of claim 3, in addition to the structure of claim 2, the outer circumference of the exhaust pipe on the downstream side of the exhaust passage is covered with a heat insulating material.

[0008]

With the above arrangement, in the invention of the first aspect, the collecting portion formed of the steel pipe connecting the exhaust manifold and the exhaust pipe is disposed on the front side of the vehicle body of the engine.
The length of the exhaust manifold from each exhaust port to the upstream of the exhaust passage, which has the largest heat radiation area, can be reduced as much as possible to reduce the amount of heat radiation. Since these three members are connected directly to the pipe wall of the exhaust pipe, the flange for connecting the exhaust manifold and the exhaust pipe is eliminated, and heat radiation from the flange is eliminated. Can be minimized. Further, when an insulator for keeping the exhaust manifold warm is provided, the insulator can be arranged close to the exhaust manifold and the gap with the exhaust manifold can be minimized, so that the warming effect can be increased by positively utilizing the insulator. The support portion fixed to the engine body allows the exhaust pipe of the common passage upstream of the catalyst and the exhaust pipe downstream of the connection position with the collecting portion to move in the axial direction of the exhaust pipe passage. Because it is supported, when the exhaust manifold and exhaust pipe are assembled to the engine, the axial displacement due to product variation and assembly error is adjusted by the support part, and the assembly accompanying the removal of the flange It does not cause deterioration of sex. Further, axial expansion due to thermal displacement of the exhaust manifold and the exhaust pipe and axial displacement due to the roll of the engine are also absorbed by the support portion.

Further, according to the invention of claim 2, the insulator from the upstream side of the exhaust passage to the collecting portion is surrounded by an insulator.
In addition, in the device of the invention, since the exhaust pipe on the downstream side of the exhaust passage is covered with a heat insulating material, in addition to the function and effect of the device of the present invention, an effective insulation of the exhaust manifold by the insulator, and furthermore, a heat insulating material The exhaust pipe is kept warm by
A decrease in the temperature of the exhaust gas in the exhaust passage is prevented, and the activation of the catalyst is promoted.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an exhaust system according to an embodiment in which the present invention is applied to an in-line four-cylinder engine. In these figures, reference numeral 1 denotes an in-line four-cylinder engine in which a crankshaft extends in a vehicle width direction with respect to a vehicle body, 2 denotes a cylinder block of the engine 1, and 3 denotes a cylinder block 2.
A cylinder head 5 connected to the upper surface of the cylinder head 3 is connected to an exhaust port (not shown) of each cylinder, which is open to the front side of the cylinder head 3 (left side in FIG. 1), and constitutes an upstream side of the exhaust passage 4. Exhaust manifold. The exhaust manifold 5 is attached to a first to fourth cylinder heads 3 of the cylinder head 3 by a mounting flange 10 provided at an upstream end thereof.
And first to fourth branch pipes 6 to 9 which are independent exhaust passages connected to the exhaust ports of the first to fourth cylinders and are respectively connected to the exhaust ports of the first to fourth cylinders. . The first to fourth branch pipes 6 to 9 are made of stainless steel pipes, the upstream ends of which are connected and fixed to the mounting flange 10 by welding, respectively, and the downstream sides are formed so as to be curved downward so as to face the engine. At the downstream end thereof, they are bundled together and connected to the upstream side of a stainless steel joint pipe 11 as a collecting portion arranged on the front side of the vehicle body of the engine. As shown in FIGS. 3 and 4, the downstream end portions of the first to fourth branch pipes 6 to 9 are arranged and bundled in a substantially square shape when viewed from the axial direction, and each cross-sectional shape is From the circular shape, it is gradually transformed into a fan shape occupying a quarter of the circle, and the bundled outer peripheries of the first to fourth branch pipes 6 to 9 are superimposed into a circular shape. The parts are fitted and connected and fixed by welding. Then, in the joint pipe 11, the exhaust passages of the respective cylinders are gathered and joined into one common passage.

The downstream end of the joint pipe 11 is connected to an exhaust pipe 12 forming a common passage downstream of the exhaust passage 4.
And is connected and fixed by welding. The exhaust pipe 12 is piped such that its downstream side extends below the engine 1 and extends rearward of the vehicle body, and its downstream end is connected to a catalyst 14 disposed on the vehicle body rear side of the engine. Further, as shown in FIG. 5, the exhaust pipe 12 has a double structure formed of an outer pipe 12a made of stainless steel and an inner pipe 12b made of stainless steel. Glass wool 13 as a heat insulating material is packed between them. On the upstream side of the exhaust pipe 12,
A boss 12c for mounting an O ₂ sensor for detecting the oxygen concentration of the exhaust gas is provided. Further, the exhaust pipe 12 has a mounting portion 1 formed at the center thereof with a slightly smaller diameter.
In 2d, the support is supported by a bracket 15 as a support fixed to the boss 2a on the rear side wall of the cylinder block 2, which is the engine 1 body side. The bracket 15 supports the exhaust pipe 12 by tightening and connecting and fixing the outer circumference of the mounting portion 12d of the exhaust pipe 12, and the bracket 15 slides on the outer circumference of the mounting portion 12d to move in the axial direction of the exhaust pipe 12. Allows movement. The catalyst 14 is disposed behind a toeboard line L indicating a toeboard that separates an engine room and a crew compartment of a vehicle body, and below a floor line M indicating a lower surface of the floor of the crew room.

In addition, the exhaust manifold 5 extends from a portion immediately downstream of the upstream end to a joint pipe 11 connected to the downstream end thereof by two insulators 16 and 17 from the vehicle front-rear direction (left-right direction in FIG. 1). It is covered with a minimal gap.

With the above configuration, in the above embodiment, since the catalyst 14 having a relatively large volume is arranged on the underfloor behind the engine room, the space in the engine room can be effectively used. Further, since the stainless steel joint pipe 11 for connecting the exhaust manifold 5 and the exhaust pipe 12 is disposed on the front side of the vehicle body of the engine, the length of the exhaust manifold 5 having the largest heat radiation area is made as short as possible. The exhaust manifold 5 and the exhaust pipe are fitted with the upstream end opening and the downstream end opening of the joint pipe 11 and are directly connected by welding. The connection between the manifold 5 and the exhaust pipe 12 does not require a flange, so that heat radiation from the flange can be eliminated, thereby minimizing the amount of heat radiation. Further, since the insulators 16 and 17 surrounding the exhaust manifold 5 as a whole are not obstructed by the flange, the gap between the exhaust manifold 5 and the exhaust manifold can be reduced to a minimum. The insulator 1
It can be used in the inner space of 6, 17 to sufficiently exhibit its heat retaining effect. Further, since the exhaust pipe 12 is formed in a double structure and the outer space is filled with glass wool 13 as a heat insulating material, the exhaust pipe can be sufficiently kept warm. From these facts, even though the catalyst 14 is arranged away from the engine 1, the activation of the catalyst 14 can be further promoted without impairing the activation. Further, when vibration generated from the engine 1 or the like is transmitted to the exhaust pipe 12, the vibration is absorbed by the glass wool 13 filled in the outer peripheral space of the exhaust pipe 12, and the vibration of the exhaust pipe 12 can be reduced. it can.

The exhaust pipe 12 is supported by the main body of the engine 1 by a bracket 15 so that the exhaust pipe 12 can be moved in the axial direction. Therefore, the exhaust manifold 5 and the exhaust pipe 12 are joined together. When assembled to the engine 1 in a state of being welded together by the pipe 11, the displacement in the axial direction due to variations and assembly errors can be adjusted by sliding between the bracket 15 and the mounting portion 12d of the exhaust pipe. It is possible to prevent the exhaust manifold 5 and the exhaust pipe 12 from being attached to the engine 1 easily. Further, the exhaust manifold 5 and the exhaust pipe 1
2, the axial elongation due to the thermal displacement and the axial displacement due to the roll of the engine can also be absorbed by the sliding between the bracket 15 and the mounting portion 12d of the exhaust pipe, so that the exhaust manifold 5 and the joint pipe 11 The thermal stress and the like at the welded portion and the welded portion between the exhaust pipe 12 and the joint pipe 11 can be reduced, and the reliability and sealability of the welded portion can be improved.

[0016]

As described above, according to the engine exhaust system of the first aspect of the present invention, the steel collecting part for directly connecting the exhaust manifold and the exhaust pipe is arranged on the front side of the vehicle body. The length of the exhaust manifold with a large heat dissipation area is shortened to reduce the amount of heat dissipation, and the flange for connection between the exhaust manifold and the exhaust pipe can be eliminated, eliminating heat dissipation from the flange and minimizing the amount of heat dissipation In addition, when the insulator for keeping the temperature of the exhaust manifold is provided, the gap between the insulator and the exhaust manifold can be minimized, so that the heat retaining effect can be sufficiently exhibited. In addition, the support portion fixed to the engine body side supports the exhaust pipe of the common passage upstream of the catalyst and the exhaust pipe downstream of the connection position with the collecting portion so as to be movable in the axial direction of the exhaust pipe passage. Since the catalyst is arranged downstream of the support, when the exhaust manifold and the exhaust pipe are assembled to the engine, displacement in the axial direction due to product variation or assembly error is caused by the support. It can be adjusted, and does not cause deterioration of the assemblability due to the elimination of the flange. Further, the axial expansion due to the thermal displacement of the exhaust manifold and the exhaust pipe and the axial displacement due to the roll of the engine are also absorbed by the support portion, so that the reliability of the connection between the exhaust manifold and the exhaust pipe and the sealing are improved. Performance can be improved. Further, in the invention of claim 2,
In addition to the function and effect of the invention of claim 1, effective insulation of the exhaust manifold by the insulator and, in the invention of claim 3, insulation of the exhaust pipe by heat insulating material are performed, so that the exhaust gas in the exhaust passage is exhausted. It is possible to prevent the temperature from lowering and promote the activation of the catalyst.

[Brief description of the drawings]

FIG. 1 is a side view of an exhaust device of an engine according to an embodiment of the present invention.

FIG. 2 is a front view of the exhaust device of the engine according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line AA of FIG.

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a sectional view taken along line CC of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 4 Exhaust passage 5 Exhaust manifold 11 Joint pipe (collection part) 12 Exhaust pipe 13 Glass wool (insulation material) 14 Catalyst 15 Bracket (support part) 16 Insulator 17 Insulator

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuhiro Okasako 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-60-26116 (JP, A) 59-79515 (JP, U) Japanese Utility Model 2-24029 (JP, U) Japanese Utility Model 2-22620 (JP, U) Japanese Utility Model 1-227813 (JP, U)

Claims (3)

(57) [Scope of request for utility model registration] An engine is mounted laterally with a crankshaft arranged in a vehicle width direction with respect to a vehicle body, and an exhaust passage extends rearward from the vehicle body front side of the engine across the engine lower side. In an exhaust system for an engine, a catalyst is disposed in an exhaust passage on a rear side of a vehicle body of the engine, and an exhaust manifold on an upstream side of the exhaust passage connected to an exhaust port of each cylinder of the engine is formed of a steel pipe. An assembly that connects the exhaust manifold and an exhaust pipe that forms a common passage downstream of the exhaust passage is formed of a steel pipe, and the assembly is disposed on the front side of the vehicle body of the engine. together they are respectively directly connected to the pipe wall of the exhaust pipe and the pipe wall of the exhaust manifold, by a support portion fixed to the engine body, the Catalyst upstream co
Exhaust pipe of the passage and downstream from the connection position with the above-mentioned collecting part
The exhaust pipe on the side is supported so as to be movable in the axial direction of a passage of the exhaust pipe. 2. The engine exhaust system according to claim 1, further comprising an insulator surrounding the exhaust passage from the upstream side to the collecting portion. 3. The exhaust system for an engine according to claim 2, wherein the outer periphery of the exhaust pipe on the downstream side of the exhaust passage is covered with a heat insulating material.