JP2002285915A - Exhaust gas recirculation passage of cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully cool recalculating exhaust gas, by elongating an exhaust gas recirculation passage in a cylinder head, without enlarging the cylinder head. SOLUTION: The exhaust gas recirculation(EGR) passage 20 is disposed in a cylinder head 11, having a plurality of cylinders #1, #2, #3, #4, for recirculating a part of exhaust gas to an intake passage as EGR gas. A second passage portion 22, constituting at least a part of the EGR passage 20, is formed to extend in the longitudinal direction (horizontal direction in Figure) of a direction arranging the cylinders of the cylinder head. Therefore, the EGR passage 20 is set to be long in the cylinder head 11, as compared with the case where the EGR passage 20 passes merely in a lateral direction (vertical direction in the figure).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation passage provided in a cylinder head of an internal combustion engine having a plurality of cylinders and configured to recirculate a part of exhaust gas to an intake passage as exhaust gas recirculation gas.

[0002]

2. Description of the Related Art For example, in an internal combustion engine such as an in-vehicle engine, an EGR device is used in which part of exhaust gas is used as exhaust gas recirculation (EGR) gas and is returned to an intake passage for the purpose of improving exhaust emission. What is provided is known. This EGR device includes an EGR passage communicating between an exhaust passage and an intake passage of an internal combustion engine, and an EG provided in the passage.
And an R valve. By adjusting the opening of the EGR valve, the amount of EGR gas (EGR amount) recirculated from the exhaust passage to the intake passage through the EGR passage is adjusted. When a part of the exhaust gas is returned to the intake passage by such an EGR device, the combustion temperature is reduced by the EGR gas, the generation of nitrogen oxides (NOx) in the combustion chamber is suppressed, and the exhaust emission is improved. .

As one form of the EGR device, for example, Japanese Utility Model Laid-Open Publication No. Sho 60-73865 proposes a technique in which a part of the EGR passage is formed inside a cylinder head. The EGR passage extends from a predetermined cylinder in the short direction of the cylinder head, and opens to the outer surface of the cylinder head. This technique attempts to cool the hot EGR gas by passing it through the inside of a cylinder head having a lower temperature.

[0004]

However, in the technology described in the above publication, if the length of the EGR passage is increased in order to increase the heat exchange efficiency, the cylinder head becomes larger.

The present invention has been made in view of such circumstances, and has as its object to secure a long passage length in the cylinder head without increasing the size of the cylinder head and to supply EGR gas. An object of the present invention is to provide an exhaust gas recirculation passage for a cylinder head that can be sufficiently cooled.

[0006]

The means for achieving the above object and the effects thereof will be described below. In the exhaust gas recirculation passage of the cylinder head provided in the cylinder head of the internal combustion engine having a plurality of cylinders and configured to recirculate a part of the exhaust gas from the cylinder to the intake passage as the exhaust gas, At least in part,
It is assumed that it is constituted by a passage portion extending in the longitudinal direction which is the cylinder arrangement direction of the cylinder head.

According to the above configuration, a part of the exhaust gas generated in each cylinder is returned to the intake passage as the exhaust gas through the exhaust gas recirculation passage in the cylinder head. The temperature of the cylinder head is usually lower than the temperature of the exhaust gas recirculation gas. For this reason, heat exchange is performed between the exhaust gas recirculation gas and the cylinder head while the exhaust gas recirculation gas flows through the exhaust gas recirculation passage, and the temperature of the exhaust gas recirculation gas decreases.

By the way, at least a part of the exhaust gas recirculation passage is constituted by a passage portion extending in the longitudinal direction which is the cylinder arrangement direction of the cylinder head. It is possible to set the passage length of the exhaust gas recirculation passage in the cylinder head longer than in the case of the above. Further, by increasing the length of the exhaust gas recirculation passage, the portion of the cylinder head involved in heat exchange with the exhaust gas recirculated gas is widened. Therefore, heat exchange between the exhaust gas recirculation gas and the cylinder head can be sufficiently performed, and the exhaust gas recirculation gas can be sufficiently cooled without increasing the size of the cylinder head.

According to a second aspect of the present invention, in the first aspect of the invention, a portion of the cylinder head different from the passage portion forms a part of the intake passage,
It is assumed that an air chamber extending in the longitudinal direction and communicating the outer surface of the cylinder head and each of the cylinders is formed.

According to the above configuration, the intake air flowing through the intake passage enters the air chamber inside the cylinder head from the opening on the outer surface of the cylinder head, and is then guided to each cylinder. On the other hand, in the process of flowing through the exhaust gas recirculation passage, the exhaust gas recirculated gas is guided in the longitudinal direction of the cylinder head by a passage portion located away from the air chamber.

According to a third aspect of the present invention, in the second aspect of the invention, the cylinder located at one end of the plurality of cylinders is a cylinder from which the exhaust gas recirculation gas is taken out,
It is assumed that an air intake of the air chamber is formed on a cylinder side opposite to a cylinder from which the exhaust gas recirculation gas is extracted, and the passage extends to a vicinity of the air intake.

According to the above configuration, part of the exhaust gas discharged from the cylinder located at one end of the plurality of cylinders is taken out to the exhaust gas recirculation passage as the exhaust gas recirculated gas. The exhaust gas recirculates through the passage in the longitudinal direction of the cylinder head and is guided to the vicinity of the air intake of the air chamber.
This air intake port is located on the side of the cylinder opposite to the cylinder (one end cylinder) from which the exhaust gas recirculation gas is taken out.
That is, the air intake port is located farthest from the cylinder from which the exhaust gas recirculation gas is extracted in the cylinder head. Therefore, a sufficient amount of heat exchange is performed between the exhaust gas recirculation gas and the cylinder head by flowing the exhaust gas recirculation gas through the exhaust gas recirculation passage set as the longest.

According to a fourth aspect of the present invention, in the first aspect of the present invention, an air chamber which forms a part of the intake passage in the cylinder head and communicates an outer surface of the cylinder head and each of the cylinders. Is formed, and the air chamber and the passage portion extend substantially parallel in the cylinder head.

According to the above configuration, the intake air flowing through the intake passage enters the air chamber inside the cylinder head from the opening on the outer surface of the cylinder head, and is then guided to each cylinder. On the other hand, the exhaust gas recirculation gas is guided in the longitudinal direction of the cylinder head by the passage portion while flowing through the exhaust gas recirculation passage. At this time, it is considered that heat exchange is also performed between the exhaust gas recirculation gas and the air chamber, and the temperature of the exhaust gas recirculation gas decreases. Here, since the air chamber and the passage extend substantially in parallel in the cylinder head, the exhaust gas recirculation gas flows along the air chamber while maintaining a substantially constant distance from the air chamber. Therefore, heat exchange between the exhaust gas recirculation gas and the cylinder head can be efficiently performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a vehicle internal combustion engine having a plurality of cylinders will be described below with reference to the drawings.

FIG. 1 shows a four-cylinder gasoline engine (hereinafter referred to as a "gasoline engine").
In the cylinder head 11 of the engine).
3 schematically illustrates passages for air, exhaust gas, and the like. In FIG. 1, the cylinders # 1, # 2, # 3, and # 4 are indicated by broken lines. The direction in which the cylinders # 1 to # 4 are arranged (the horizontal direction in FIG. 1) is referred to as the longitudinal direction, and the direction substantially perpendicular to the longitudinal direction (the vertical direction in FIG. 1) is referred to as the lateral direction.

The cylinder head 11 is connected to an intake passage for guiding air outside the engine to the combustion chambers of the cylinders # 1 to # 4. A part of the intake passage is constituted by an air chamber 13 provided in the cylinder head 11. The air chamber 13 corresponds to an intake manifold used in a general engine, and is formed of a long and narrow space extending in the longitudinal direction between the cylinders # 1 and # 4 at both ends in the cylinder head 11. Air chamber 13 and each cylinder # 1
The # 4 is communicated with the intake port 14 provided in the cylinder head 11.

The air intake port 15 of the air chamber 13 is connected to the cylinders # 1 to # 1 of the cylinder head 11 with the air chamber 13 interposed therebetween.
It is open on the outer surface 11a on the opposite side (lower side in FIG. 1) of # 4. In the present embodiment, the air intake 15 is
1a, a cylinder # 4 from which EGR gas to be described later is extracted
The cylinder # 1 is open to the opposite side. And outer surface 1
In 1a, a throttle body 16 is attached to a location corresponding to the air intake port 15. The throttle body 16 is a mechanism for adjusting the amount of intake air flowing through the intake passage, and includes a throttle valve 17 and the like.

An exhaust passage for discharging exhaust gas generated in the combustion chambers to the outside of the engine is connected to the combustion chambers of the cylinders # 1 to # 4. A part of the exhaust passage is constituted by exhaust ports 18 provided for the cylinders # 1 to # 4 provided in the cylinder head 11. Each exhaust port 18
Regarding the cylinder head 11, an outer surface 11b opposite to the outer surface 11a where the air intake port 15 is opened, and each cylinder # 1
~ $ 4.

The cylinder head 11 is provided with an EGR device 19 for returning a part of the exhaust gas to the intake passage as exhaust gas recirculation (EGR) gas. EGR device 1
Reference numeral 9 includes an EGR passage 20 for communicating between the exhaust passage and the intake passage. Most of the EGR passage 20 is constituted by a first passage 21 and a second passage 22 provided in the cylinder head 11.

The first passage portion 21 has cylinders # 1 and # 4 at both ends.
Of these, the cylinder # 4 extends in the short direction of the cylinder head 11 from the cylinder # 4 on the opposite side of the air intake port 15 in the air chamber 13, and is connected to an EGR valve 23 attached to the outer surface 11a. The EGR valve 23 is a valve for adjusting the amount of EGR gas flowing through the EGR passage 20. Also,
The second passage portion 22 is provided between the cylinders # 1 to # 4 with the air chamber 13 interposed therebetween.
(Lower side in FIG. 1). The second passage portion 22 extends in the longitudinal direction of the cylinder head 11 from the EGR valve 23 to the vicinity of the air intake port 15, and is connected to a position downstream of the throttle valve 17 in the throttle body 16. Substantially the entire second passage portion 22 is
It is located at approximately the same height as the air chamber 13. Thus, the second passage portion 22 and the air chamber 13 are connected to the cylinder head 1.
1 extend substantially in parallel.

A water jacket (not shown) is formed in the cylinder head 11. The water jacket is a cooling water passage through which the cooling water flows, thereby cooling the combustion chamber, the EGR passage 20, and the like. The air chamber 13, the intake port 14, the exhaust port 18, the first passage 21, the second passage 22, the water jacket, and the like are formed integrally with the body of the cylinder head 11 at the time of casting. It is.

According to the present embodiment configured as described above, the intake air flowing through the intake passage outside the cylinder head 11 flows into the air chamber 13 from the air intake port 15 and then from each intake port 14 Guided to cylinders # 1 to # 4. On the other hand, in the intake stroke of the engine,
# 4 pressure and throttle valve 1 in intake passage
7 is lower than the outside air (atmospheric pressure). This intake pressure acts on the EGR passage 20, and the cylinder # 4
Of the exhaust gas discharged from the
As shown by an arrow in FIG. 1, the first passage portion 21, the EGR
The gas is returned to the intake passage through the valve 23, the second passage portion 22, and the like.

More specifically, the EGR gas is supplied to the first passage 21
Thereby, it is guided in the short direction of the cylinder head 11.
After passing through the first passage portion 21, the EGR gas once goes out of the cylinder head 11, but passes through the EGR valve 23 and flows into the second passage portion 22 in the cylinder head 11 again. The EGR gas is guided in the longitudinal direction of the cylinder head 11 by the second passage portion 22, and once reaching the vicinity of the air intake port 15, once exits the cylinder head 11 and enters the throttle valve 1 of the throttle body 16 in the intake passage.
7 flows downstream. Thereafter, the EGR gas is released to the air chamber 13 through the air intake port 15 and is guided to each of the cylinders # 1 to # 4 through each of the intake ports 14. This E
The GR gas lowers the combustion temperature, suppresses the generation of nitrogen oxides (NOx) in the combustion chamber, and improves exhaust emissions.

After the engine is warmed up, the temperature of the cylinder head 11 is lower than the temperature of the EGR gas. E
While the temperature of the GR gas is usually 200 to 300 ° C., the temperature of the cylinder head 11 is about 100 ° C.
The reason why the temperature of the cylinder head 11 is low is mainly that cooling water or the like flows through a water jacket provided in the cylinder head 11. Therefore, EG
In the process of the R gas flowing through the first passage portion 21 and the second passage portion 22, heat exchange is performed between the EGR gas and the cylinder head 11, and the temperature of the EGR gas decreases. By lowering the temperature of the EGR gas in this way, the intake air temperature during operation of the EGR device 19 decreases, and the effect of suppressing the emission of nitrogen oxides (NOx) is large.

According to the above-described embodiment, the following effects can be obtained. (1) The second part which forms at least a part of the EGR passage 20
Since the passage portion 22 extends in the longitudinal direction of the cylinder head 11, the passage length of the EGR passage 20 in the cylinder head 11 is longer than that of the related art in which the EGR passage is simply passed in the short direction of the cylinder head. Can be set. Accordingly, in the cylinder head 11, E
A portion related to heat exchange with the GR gas is widened. Therefore,
The heat exchange between the EGR gas and the cylinder head 11 is sufficiently performed without increasing the size of the cylinder head 11, so that the EGR gas can be sufficiently cooled. Generally, in a vehicle engine, an EGR cooler is used to cool EGR gas. However, in the present embodiment, the same effect can be obtained without using the EGR cooler.

(2) By providing the air intake port 15 on the side of the cylinder # 1 opposite to the cylinder # 4 from which the EGR gas is taken out, the two 15 and # 4 are largely separated from each other, so that the EGR in the cylinder head 11 The length of the passage 20 is substantially the longest. Therefore, the amount of heat exchange between the EGR gas and the cylinder head 11 is increased by flowing the EGR gas through the EGR passage 20 which is set to be the longest.
The temperature of the GR gas can be lowered. And
As the number of cylinders increases, the length of the second passage portion 22 can be increased, and a large cooling effect can be expected.

(3) First passage portion 21 and second passage portion 22
Constitutes most of the EGR passage 20. Therefore, only the first passage portion 21 or the second passage portion 22
Compared with the case where the EGR passage 20 is constituted only by the EGR passage 20.
By setting the passage length of the passage 20 to be long, the cooling performance of the EGR gas can be further enhanced.

(4) In the cylinder head 11, an air chamber 13 is formed between the cylinders # 1 to # 4 and the outer surface 11a. The length of the cylinder head 11 in the short direction is increased by the amount of the air chamber 13. Accordingly, the first passage portion 21 becomes longer than in the case where the air chamber 13 is not provided. This is also effective in elongating the EGR passage 20 to enhance the cooling performance.

(5) Connect the EGR valve 23 to the cylinder head 1
1 is attached to the outer surface 11a. Also, the first passage portion 21
And the second passage portion 22 is constituted by a space, and their ends are connected to the EGR valve 23. That is, the EG connecting the cylinder # 4 from which the EGR gas is extracted and the EGR valve 23
An R pipe is integrally taken into the cylinder head 11, and an EGR pipe connecting the EGR valve 23 and the air chamber 13 is integrally taken into the cylinder head 11. For this reason, these two EGR pipes become unnecessary. In addition, among components of a general EGR device, a gasket, a cooling water hose, an EGR cooler, and the like can be omitted, and the number of components can be reduced.

(6) The EGR passage 20 is formed by casting together with the main body of the cylinder head 11 in the step of casting the cylinder head 11. Thus, in the casting process originally performed for the formation of the main body portion,
The EGR passage 20 is also formed together. For this reason, EGR
No special process for forming the passage is required.

(7) Although the temperature of the cylinder head 11 is lower immediately after starting the engine than after warming up, the EGR passage 20
Heat is exchanged between the EGR gas flowing through the cylinder head 11 and the cylinder head 11. As described above, since the EGR passage 20 is long, the amount of heat exchange is large. For this reason, the temperature of the cylinder head 11 can be raised at an early stage, and the warm-up property can be improved.

(8) The second passage section 22 is formed on the opposite side of each of the cylinders # 1 to # 4 with the air chamber 13 interposed therebetween. That is, the second position is set as far as possible from each of the cylinders # 1 to # 4.
A passage portion 22 is formed. For this reason, in the cylinder head 11, the temperature of the combustion chambers of the cylinders # 1 to # 4 and the vicinity thereof is particularly higher than the temperature of other places. Thereby, the influence of the temperature of the combustion chamber is reduced, and the EGR gas can be efficiently cooled.

(9) When the EGR gas flows through the second passage portion 22, heat exchange is also performed between the EGR gas and the air chamber 13, and it is considered that the temperature of the EGR gas decreases. Here, in the present embodiment, the air chamber 13 and the second passage portion 22 extend substantially in parallel in the cylinder head 11. Therefore, the EGR gas flows along the air chamber 13 while maintaining a substantially constant distance from the air chamber 13. Therefore,
Heat exchange between the EGR gas and the cylinder head 11 can be performed efficiently.

The present invention can be embodied in another embodiment described below. -In the said embodiment, the 1st passage part 21 and the 2nd passage part 22
2, the two passages 21 and 22 are connected to each other in the cylinder head 11, and the EGR valve 23 is connected to the second passage 22 and the air chamber 13 as shown in FIG.
May be arranged between the air intake port 15 and the air intake port 15. Therefore,
In this case, the downstream end of the first passage portion 21 and the upstream end of the second passage portion 22 do not open to the outer surface 11a of the cylinder head 11. Even in this case, the same operation and effect as in the above embodiment can be obtained. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals.

In the above case, the EGR valve 23 may be disposed in the throttle body 16 as shown in FIG. 2, or may be disposed at a location different from the throttle body 16.

In the above embodiment, the second passage portion 22 is
The other side of each cylinder # 1 to # 4 across the air chamber 13 (the outer surface 1
1a), but may be formed at a different location, for example, above or below the air chamber 13.

In the above embodiment, the air intake port 15 of the air chamber 13 is provided on the side opposite to the cylinder # 4 from which the EGR gas is taken out and in the vicinity of the cylinder # 1 located at the end.
It may be provided near a different cylinder, for example, the cylinder # 2. However, from the viewpoint of enhancing the cooling performance by lengthening the second passage portion 22, it is preferable to provide the air intake port 15 near the cylinder # 1 which is the farthest from the cylinder # 4.

The air chamber 13 in the above embodiment may be omitted, and the intake manifold may be provided outside the cylinder head 11. The first passage portion 21 may be omitted, and the EGR passage 20 in the cylinder head 11 may be constituted by only the second passage portion 22.

In addition, technical ideas that can be grasped from the above embodiments will be described together with their effects. (A) In the exhaust gas recirculation passage of the cylinder head according to any one of claims 1 to 4, a first passage portion extending in a short direction of the cylinder head is further provided, and extends in a longitudinal direction of the cylinder head. The passage portion is connected to the first passage portion as a second passage portion, and a predetermined cylinder communicates with the intake passage through the first passage portion and the second passage portion.

According to the above configuration, as compared with the case where the exhaust gas recirculation passage is constituted only by the first passage portion, the length of the exhaust gas recirculation passage in the cylinder head is increased by the increase of the second passage portion. Therefore, heat exchange between the exhaust gas recirculation gas and the cylinder head is sufficiently performed, and the cooling performance of the exhaust gas recirculation gas can be enhanced.

(B) In the exhaust gas recirculation passage of the cylinder head described in (2), (3), or (4), the passage is provided on the opposite side of each of the cylinders with the air chamber interposed therebetween. .

According to the above construction, in the cylinder head, the temperature of the combustion chamber of the cylinder and its vicinity becomes particularly high as compared with the temperature of other parts, but the exhaust gas recirculation passage is provided at a place as far as possible from the cylinder. This makes it less likely to be affected by the temperature of the combustion chamber, so that the exhaust gas recirculation gas can be efficiently cooled.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the concept of an embodiment of an exhaust gas recirculation passage of a cylinder head according to the present invention.

FIG. 2 is a schematic diagram showing the concept of another embodiment of the exhaust gas recirculation passage of the cylinder head of the present invention.

[Explanation of symbols]

11: cylinder head, 11a: outer surface, 13: air chamber,
15 ... Air intake port, 20 ... EGR passage, 22 ... Second passage portion, # 1, # 2, # 3, # 4 ... Cylinder.

Claims (4)

[Claims] 1. An exhaust gas recirculation passage of a cylinder head provided in a cylinder head of an internal combustion engine having a plurality of cylinders and recirculating a part of exhaust gas from the cylinder to an intake passage as exhaust gas recirculation gas. Are constituted by a passage portion extending in a longitudinal direction which is a cylinder arrangement direction of the cylinder head. 2. A portion of the cylinder head, which is different from the passage portion, forms a part of the intake passage, extends in the longitudinal direction, and communicates the outer surface of the cylinder head and each of the cylinders. The exhaust gas recirculation passage of the cylinder head according to claim 1, wherein a chamber is formed. 3. A cylinder located at one end of the plurality of cylinders is a cylinder from which the exhaust recirculation gas is taken out, and an air intake of the air chamber is a cylinder from which the exhaust recirculation gas is taken out. 3. The exhaust gas recirculation passage of the cylinder head according to claim 2, wherein the passage portion is formed on a side of the cylinder opposite to the cylinder, and the passage extends to a vicinity of the air intake port. 4. An air chamber, which forms a part of the intake passage and communicates with an outer surface of the cylinder head and each of the cylinders, is formed in the cylinder head. 2. The exhaust gas recirculation passage for a cylinder head according to claim 1, wherein the exhaust gas recirculation passage extends substantially in parallel in the head.