JP7063679B2 - EGR device for internal combustion engine - Google Patents

Description

The present invention relates to an EGR device for an internal combustion engine.

In internal combustion engines for automobiles and the like, it is widely practiced to provide an EGR device that recirculates a part of exhaust gas to an intake system in order to promote purification of exhaust gas. The EGR device is often equipped with an EGR cooler such as a water-cooled type for cooling the EGR gas.

As an example of an EGR apparatus provided with an EGR cooler, in Patent Document 1, the lower end of an EGR take-out pipe (upstream EGR pipe) is connected to the downstream end of a catalyst case, and the upper and lower EGRs are vertically elongated at the upper end of the EGR take-out pipe. In a configuration in which a cooler is connected and the upper end of the EGR cooler is connected to the EGR valve, the EGR take-out pipe is formed in a substantially inverted L-shaped posture when viewed from the direction facing the exhaust side of the engine body, so that the catalyst case can be used. It is disclosed that the thermal expansion is absorbed by the bending deformation of the EGR take-out pipe.

Japanese Patent No. 5805206

In Patent Document 1, the lower end of the EGR take-out pipe is connected to the front surface of the catalyst case when viewed from a direction orthogonal to the exhaust side surface of the engine body. Therefore, the EGR take-out pipe greatly overhangs the outside of the exhaust side surface of the engine body, but in this configuration, when other members are arranged outside the exhaust side surface of the engine body, the other members hit the EGR take-out pipe. Since it is necessary to select the placement position so that it does not exist, there is a concern that the freedom of design of the engine will be impaired and the size of the engine will increase.

The invention of the present application has been made to improve such a situation.

The EGR apparatus of the present invention is
"A vertically long catalyst case in which a catalyst for purifying exhaust gas is built in the exhaust side surface of the engine body, an EGR take-out pipe branched from a portion of the catalyst case downstream of the catalyst, and the EGR take-out. We have placed an EGR cooler connected to the end of the pipe. "
It is a basic configuration.

The invention of claim 1 is based on the above basic configuration.
"The EGR cooler is arranged in one of two areas divided into front and rear across the catalyst case when viewed from the side facing the exhaust side surface of the engine body with the crank axis direction as the front-rear direction. Being done
The EGR take-out pipe is connected to the surface of the catalyst case facing the one area, and a part of the EGR take-out pipe meanders toward the EGR cooler so as to pass between the catalyst case and the engine body. ,
Moreover, the outlet of the EGR cooler is connected to the engine body via an intermediate pipe in the one area. "
It is configured as.

Further, the invention of claim 2 is based on the above basic configuration.
" With the crank axis direction as the front-rear direction, the EGR take-out pipe is placed in one of two areas divided into front and rear across the catalyst case when viewed from the side facing the exhaust side surface of the engine body. After being exposed, it is bent in an S shape in the side view so that it once enters between the catalyst case and the engine body and then is exposed to the one area.
Moreover, the portion of the EGR take-out pipe that has entered between the catalyst case and the engine body is arranged on the side of the one area of the axis of the catalyst case in the side view. "
It is configured as.

The invention of the present application further has various configurations. As an example, in the invention of claim 3, in claim 1 or 2,
"The EGR take-out pipe is three-dimensionally bent so as to have a plurality of bent portions separated in the vertical direction and the front-rear direction in the side view."
It is configured as.

As an example of development of any one of claims 1 to 3 , claim 4
"The EGR cooler has a vertically elongated shape in which an exhaust gas inlet to which the EGR take-out pipe is connected is opened at the lower end and an exhaust gas outlet is opened at the upper end, and the exhaust gas inlet is the catalyst case. Is open toward the main body of the engine. "
It is configured as.

The invention of claim 1 does not contradict the invention of claim 2. It is suitable to combine them with each other.

In the present invention, the EGR take-out pipe has a meandering shape and is easily bent and deformed, so that even if the exhaust passage is thermally expanded, the elongation can be accurately absorbed. Therefore, the EGR cooler is not strongly pulled due to the thermal expansion of the exhaust passage, and the EGR cooler can be stably held.

A part of the EGR take-out pipe is located behind the catalyst case (the space between the catalyst case and the engine body), and the entire EGR take-out pipe is on the outside of the catalyst case (on the opposite side of the cylinder block). It can be placed in a state where it does not protrude. That is, the space between the catalyst case and the engine body is a dead space, and this dead space can be used to form the EGR take-out pipe in a meandering form.

Therefore, when the other members are arranged outside the exhaust passage (catalyst case) of the engine body, the EGR take-out pipe does not get in the way, the design freedom can be improved, and the internal combustion engine can be made compact. I can contribute.

In the present invention, when the exhaust passage is thermally expanded and expanded and deformed, the EGR cooler is subjected to an action of rotating with the attachment portion to the engine body as a fulcrum. Therefore, the tensile force hardly acts on the EGR cooler, and it is possible to prevent the joint with the engine body from being damaged or deformed.

Therefore, in this aspect as well, the invention of the present application does not require the EGR take-out pipe protruding to the outside of the exhaust passage as in Patent Document 1, and as a result, the freedom of design can be improved and the internal combustion engine can be made compact. Can also contribute.

A catalyst case is generally arranged in the exhaust passage, but since the catalyst case has a considerable outer diameter, a large space is vacant on the side of the catalyst case in terms of side view. In the present invention, the EGR cooler can be arranged by effectively utilizing the space (one area) on the side of the catalyst case, but as in the embodiment , the EGR is viewed from the direction facing the exhaust side surface of the engine body. If the cooler is formed so that its cross-sectional shape is long in the depth direction (long in the direction orthogonal to the crank axis and cylinder axis ), the placement area (projected area) of the EGR cooler in the side view of the engine can be reduced. In arranging the members of the above, it is possible to suppress the trouble of designing so as to avoid interference with the EGR cooler, and to contribute to the improvement of design freedom.

When the EGR take-out pipe is three-dimensionally bent as in claim 3, the EGR take-out pipe can be used in any of the vertical direction, the front-rear direction (crank axis direction) , and the left-right direction (the direction facing the exhaust side surface of the engine body) . Since the catalyst case bends and deforms easily, even if the catalyst case thermally expands or swings in the front-back direction or the left-right direction, the thermal expansion and swinging movement can be easily absorbed by the bending deformation.
When the bracket is used for mounting the EGR cooler as in the embodiment, the mounting of the EGR cooler is reinforced by the bracket, so that the stability of the EGR cooler can be further improved.

It is a schematic side view of an internal combustion engine. It is a view (rear view) of II-II of FIG. It is a partially enlarged view of FIG. (A) is a rear view of IVA-IVA in FIG. 3, and (B) is a partially broken plan view of IVA-IVA in FIG.

(1). Overview Next, embodiments of the present invention will be described with reference to the drawings. In the following, words such as front-back and side view are used to specify the direction, but the front-back direction is the crank axis direction as claimed , and the side where the timing chain and the crank pulley (neither are shown) are provided. Is in front. The vertical direction is the vertical direction, and the left-right direction is the direction orthogonal to the vertical direction and the crank axis direction (the direction facing the exhaust side surface of the engine body) . Just in case, the direction is clearly shown in the drawing.

The basic configuration of the internal combustion engine is the same as the conventional one, and as shown in FIGS. 1 and 2, the cylinder block 1 in which a plurality of cylinder bores (not shown) are formed as the core member of the engine body and the cylinder block 1 are fixed to the top surface thereof. It also has a cylinder head 2. The parallel diagonal lines drawn in FIG. 1 indicate the rear end surface of the cylinder block 1, not the cross section.

An oil pan 3 is fixed to the lower surface of the cylinder block 1, and a head cover 4 is fixed to the upper surface of the cylinder head 2. Further, a cooling water distribution unit 5 is arranged on the rear surface of the cylinder head 2. A front cover 6 that covers the timing chain is fixed to the front surfaces of the cylinder block 1 and the cylinder head 2, and the front end portion of the head cover 4 overlaps the front cover 6 from the bore axis direction. The mission case 7 is fixed to the rear surfaces of the cylinder block 1 and the oil pan 3 with a large number of bolts.

The cylinder head 2 of the present embodiment is a type having a built-in exhaust collecting portion, and one exhaust outlet is opened on the exhaust side surface, and a catalyst is provided at this exhaust outlet via an elbow pipe 8 as a part of an exhaust passage. Case 9 is connected. The elbow pipe 8 includes a flange plate 10, and the flange plate 10 is fixed to the cylinder head 2 with bolts (and nuts).

The catalyst case 9 has a vertically elongated shape, and has a straight portion 9a containing a catalyst, an upper cone portion 9b having an upper constriction integrally provided at the upper end thereof, and a lower constriction integrally provided at the lower end of the straight portion 9a. It has a lower cone portion 9c, and an exhaust joint pipe 12 provided with a flange plate 11 is integrally provided at the lower end of the lower cone portion 9c.

As shown in FIGS. 1 and 3, the catalyst case 9 is tilted at a slight angle with respect to the vertical line so as to shift backward as it goes down in the side view. Further, as shown in FIG. 2, in the rear view (and front view), the cylinder block 1 is tilted slightly away from the cylinder block 1 as it goes down (the tilt in the rear view is slight, and the exhaust side surface of the cylinder block 1 is tilted). It can be said that they are almost parallel.)

(2). EGR device Next, the EGR device will be described. In the lower cone portion 9c of the catalyst case 9, the upper portion and the rear surface portion thereof (that is, toward the rear side area (one area) of the two areas divided into front and rear across the catalyst case 9 in the side view of the engine). The lower end (upstream end) of the EGR take-out pipe 13 for taking out the EGR gas is connected to the surface of the pipe by welding or the like. In the display of FIG. 4B, the receiving member 9d into which the lower end of the EGR take-out pipe 13 is fitted is fixed to the lower cone portion 9c of the catalyst case 9 by welding, but the lower end of the EGR take-out pipe 13 is fixed to the lower cone portion 9c. The tubular portion into which the is fitted may be formed by burring.

The EGR take-out pipe 13 meanders and extends upward, the lower end of the EGR cooler 14 is connected to the upper end (downstream end), and the upper end of the EGR cooler 14 is via an L-shaped intermediate pipe 15 and a flange plate 16. It is fixed to the rear side surface of the cylinder head 2. The EGR cooler 14 is arranged on the side (lateral direction) of the catalyst case 9 in the side view of the engine, and is arranged in the area behind the catalyst case 9 in the direction of the engine.

As shown in FIG. 2, an EGR internal passage 17 opened to the exhaust side surface and the intake side surface is formed at the rear portion of the cylinder head 2, and the intermediate pipe 15 is connected to the start end of the EGR internal passage 17.

As shown in FIGS. 1 and 3, the EGR take-out pipe 13 meanders in a substantially S shape in a side view, and is bent in an inverted L shape in a rear view as shown in FIG. 4 (A). To be precise, the EGR take-out pipe 13 has a first portion 13a connected to the catalyst case 9, a third portion 13c connected to the EGR cooler 14, and a second portion 13b connecting the two. The first portion 13a and the second portion 13b are connected via the first bent portion 18, and the second portion 13b and the third portion 13c are connected via the second bent portion 19.

The lower end of the first portion 13a is connected to a portion substantially directly behind the lower cone portion 9c in the catalyst case 9, and as shown in FIG. 4A, the lower end thereof approaches the cylinder head 2 as it goes upward in the rear view. While tilting, it is tilted diagonally backward in the side view.

The first portion 13a and the second portion 13b are bent on almost the same plane. Therefore, as shown in FIG. 4A, the second portion 13b is inclined so as to approach the cylinder block 1 as it goes upward in the rear view, and is inclined forward as shown in FIG. 3 in the side view. There is. That is, the first portion 13a and the second portion 13b are in opposite postures when viewed from the side. As shown in FIG. 4B, the first portion 13a and the second portion 13b have an overall shape of a glyph as shown in FIG. 4B.

In the side view, the third portion 13c is inclined diagonally upward so as to go backward as it goes up, and in the front view and the rear view of the engine, as shown in FIG. 4 (A), the cylinder increases as it goes up. It is tilted away from block 1. Therefore, the second portion 13b and the third portion 13c are gently curved in a dogleg shape as a whole. The second portion 13b and the third portion 13c are in the form of making a U-turn as shown in FIG. 4B in a plan view.

After all, the EGR take-out pipe 13 meanders in an S-shape or a state close to it in the side view and the plan view, and is bent in the L shape in the rear view . That is, the EGR take-out pipe 13 has two bent portions 18 and 19 separated in the vertical direction and the left-right direction of the engine (front-back direction in the side view of the engine), and is three-dimensionally meandering. It is designed to easily bend and deform in either the direction or the left-right direction. Therefore, even if the catalyst case 9 thermally expands or swings in the front-rear direction or the left-right direction, the thermal expansion and the swinging movement can be easily absorbed by bending and deformation.

The EGR cooler 14 has a box shape having an elongated rectangular cross-sectional shape and is vertically elongated, and has an exhaust gas inlet at the lower end and an exhaust gas outlet at the upper end. Then, as shown in FIG. 3, in the side view, it is inclined so as to go backward as it goes up. Therefore, from the side view, the catalyst case 9 and the EGR cooler 14 are in an inverted C-shaped posture (or a V-shaped posture) in which the distance between the catalyst case 9 and the EGR cooler 14 is widened upward.

Of the EGR take-out pipe 13, the entire third portion 13c and about half of the second portion 13b are hidden behind the catalyst case 9 in a side view (to be exact, between the catalyst case 9 and the cylinder block 1). It is in the space of.). Then, in the rear view of the engine, for example, as shown in FIG. 4A, the EGR cooler 14 and the catalyst case 9 overlap each other, but since the EGR cooler 14 is arranged behind the catalyst case 9, EGR The cooler 14 and the catalyst case 9 do not hit each other.

Further, the EGR cooler 14 has a rectangular cross-sectional shape having a width direction X and a longitudinal direction Y when viewed from the axial direction thereof, but as shown in FIG. 4, the longitudinal direction Y is the lateral view of the engine. It is arranged in a posture that is in the depth direction (horizontal direction) . Therefore, the area (projected area) in the side view is much smaller than that in the case where the width direction X is the posture in the depth direction in the side view.
As described above, the third portion 13c of the EGR take-out pipe 13 is inclined diagonally upward so as to go backward as it goes up in the side view, and the cylinder block as it goes up in the front view and the rear view of the engine. It is tilted away from 1 and, as shown in FIG. 4, the third portion 13c faces between the catalyst case 9 and the cylinder block 1 when viewed from the EGR cooler 14. Therefore, the exhaust gas inlet of the EGR cooler 14 is also open toward the space between the catalyst case 9 and the cylinder block 1.

The EGR cooler 14 is a water-cooled type, and a cooling water introduction port 20 is provided in the lower part and a cooling water discharge port 21 is provided in the upper part. The cooling water discharge port 21 and the cooling water introduction port 20 are arranged separately on the left and right in the side view of FIGS. 1 and 3.

The flange plate 16 fixed to the cylinder head 2 has a substantially longitudinal shape in the front-rear direction, and its front end portion and rear end portion are fixed to the cylinder head 2 with bolts. Then, as shown in FIG. 4, the upper end portion of the EGR cooler 14 and the flange plate 16 are fixed by the bracket 22. The upper end of the bracket 22 is welded to the flange plate 16, the lower end is welded to the side surface of the EGR cooler 14 (the surface facing the cylinder head 2), and the upper end and the lower end are connected by an inclined portion. There is.

The bracket 22 is in a posture that overlaps with the intermediate pipe 15 in a side view (for this reason, the bracket 22 does not appear in FIGS. 1 and 3). The bracket 22 can also be fixed to the exhaust side surface of the cylinder head 2. However, if it is fixed to the flange plate 16 as in the present embodiment, the entire EGR device can be unitized, so that there is an advantage that the mounting work becomes easy.

(3). Summary As already mentioned, the catalyst case 9 stretches due to thermal expansion and swings due to the vibration of the engine, but these stretches and swings are absorbed by the deformation of the EGR take-out pipe 13 and are intermediate. A strong external force does not act on the joint between the pipe 15 and the flange plate 16. Therefore, the phenomenon that the intermediate pipe 15 is detached from the flange plate 16 does not occur, and high durability can be maintained.

Further, since the catalyst case 9 and the EGR cooler 14 are in an inverted C-shaped (or V-shaped) posture, when the catalyst case 9 thermally expands, the EGR take-out pipe 13 and the EGR cooler 14 are at the upper ends of the intermediate pipe 15. It receives an external force that rotates with the EGR cooler 14 as a fulcrum, and the external force that pulls the EGR cooler 14 in the longitudinal direction is small.

Then, the external force that rotates the EGR take-out pipe 13 and the EGR cooler 14 is mainly absorbed by the deformation of the EGR take-out pipe 13. Also in this aspect, it is possible to prevent an excessive load from being applied to the joint portion between the intermediate pipe 15 and the flange plate 16 and ensure high durability.

In the present embodiment, the EGR take-out pipe 13 is three-dimensionally bent and is in a state close to a spiral. Therefore, the EGR gas smoothly flows through the EGR take-out pipe 13. Therefore, it is possible to prevent the EGR gas from hitting the bent portion strongly and accelerating the deterioration while forming the EGR take-out pipe 13 in a meandering form.

Since the EGR cooler 14 is longer in the depth direction in the side view of the engine, the area occupied by the EGR cooler 14 in the side view is smaller. Therefore, in arranging other members behind the catalyst case 9, design freedom can be improved.

The invention of the present application can be variously embodied in addition to the above-described embodiments. For example, the upper end portion of the EGR cooler 14 may be directly overlapped and fixed to the exhaust side surface of the cylinder head 2 without using the intermediate pipe 15. In the embodiment, the EGR take-out pipe 13 is provided with two bends and meandered, but may be formed into a form having one or three or more bends, or may be formed in a spiral shape in which the bends are not clear. It is also possible.

The present invention can be embodied in an EGR device for an internal combustion engine. Therefore, it can be used industrially.

1 Cylinder block 2 Cylinder head 8 Elbow pipe that constitutes the exhaust passage 9 Catalyst case that constitutes the exhaust passage 13 EGR take-out pipe 13a 1st part 13b 2nd part 13c 3rd part 14 EGR cooler 1
15 Intermediate pipe 16 Flange plate 18, 19 Bent part 22 Bracket

Claims (4)

An vertically long catalyst case having a catalyst for purifying exhaust gas built in the exhaust side surface of the engine body, an EGR take-out pipe branched from a portion of the catalyst case downstream of the catalyst, and the EGR take-out pipe. It is a configuration in which the EGR cooler connected to the end of is placed.
With the crank axis direction as the front-rear direction, the EGR cooler is arranged in one of two areas divided into front and rear across the catalyst case in a side view seen from the direction facing the exhaust side surface of the engine body. hand,
The EGR take-out pipe is connected to the surface of the catalyst case facing the one area, and a part of the EGR take-out pipe meanders toward the EGR cooler so as to pass between the catalyst case and the engine body. ,
Moreover, the outlet of the EGR cooler is connected to the engine body via an intermediate pipe in the one area.
EGR device for internal combustion engine. An vertically long catalyst case having a catalyst for purifying exhaust gas built in the exhaust side surface of the engine body, an EGR take-out pipe branched from a portion of the catalyst case downstream of the catalyst, and the EGR take-out pipe. It is a configuration in which the EGR cooler connected to the end of is placed.
With the crank axis direction as the front-rear direction, the EGR take-out pipe is exposed to one of two areas divided into front and rear across the catalyst case when viewed from the side facing the exhaust side surface of the engine body. Then, it is bent in an S shape in the side view so that it once enters between the catalyst case and the engine body and then is exposed to the one area.
Further, the portion of the EGR take-out pipe that has entered between the catalyst case and the engine body is arranged on the side of one of the areas of the catalyst case with respect to the axial center in the side view.
EGR device for internal combustion engine. The EGR take-out pipe is three-dimensionally bent so as to have a plurality of bent portions separated in the vertical direction and the front-rear direction in the side view.
The EGR device for an internal combustion engine according to claim 1 or 2. The EGR cooler has a vertically elongated shape in which an exhaust gas inlet to which the EGR take-out pipe is connected is opened at the lower end and an exhaust gas outlet is opened at the upper end, and the exhaust gas inlet is the catalyst case. It is open toward the main body of the engine,
The EGR device for an internal combustion engine according to any one of claims 1 to 3.

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