JP2014043772A - Cylinder head - Google Patents

Abstract

In a cylinder head (3) in which an EGR passage (12) for cooling a part of exhaust gas (EGR gas) of an engine (1) and introducing it into an intake side (4) of the engine (1) is integrally provided, The cooling efficiency of EGR gas can be improved as much as possible.
An EGR passage 12 is installed in the vicinity of a water jacket 3d provided in a cylinder head 3. In the EGR passage 12, an intermediate region 12c from the inlet 12a side to the outlet 12b side is provided with a plurality of distribution spaces 21 to 23 partitioned by a partition wall portion 12d of the cylinder head 3 so as to be adjacent to each other. The center of the inlet 12a and the center of the outlet 12b are offset.
[Selection] Figure 4

Description

  The present invention relates to a cylinder head having a structure capable of cooling EGR gas using a coolant.

  Conventionally, exhaust gas recirculation (EGR) devices are used in internal combustion engines such as engines. In the EGR mounting, the EGR gas is cooled by the EGR cooler before returning the EGR gas to the intake side of the cylinder head because of the relationship of introducing the EGR gas to the intake side of the cylinder head.

  This EGR cooler is generally installed outside the cylinder head. For example, in Patent Document 1, an EGR gas is taken from an exhaust pipe to an EGR take-out pipe and a head passage in the cylinder head without using an EGR cooler. , The EGR valve and the passage in the second head are introduced into the intake manifold.

  The passage in the second head is along one end side of the cylinder head in the combustion chamber arrangement direction (longitudinal direction of the cylinder head) in the vicinity of the water jacket and in a direction orthogonal to the combustion chamber arrangement direction (short direction of the cylinder head). Is provided.

  For example, Patent Document 2 discloses a configuration in which an EGR passage member is inserted into a water jacket of a cylinder head.

  The EGR passage member is installed along the short direction of the cylinder head. The EGR passage member has a configuration in which a plurality of hollow tubes are combined so as to be adjacent to each other, and is formed of, for example, a metal material (for example, iron-based metal) that can be press-molded. One opening of each hollow tube serves as an EGR gas inlet, and the other opening of each hollow tube serves as an EGR gas outlet. And when EGR gas is distribute | circulated through each hollow tube, this EGR gas is heat-exchanged with the cooling fluid in a water jacket, and is cooled.

  For example, Patent Document 3 discloses a configuration in which an EGR passage portion is integrally formed in a water jacket of a cylinder head.

  The EGR passage portion is installed along the short direction of the cylinder head. The EGR passage portion is configured so that EGR passages composed of a plurality of hollow spaces are connected to be adjacent to each other in a comb-like shape. For example, the EGR passage portion is formed at the same time when the cylinder head is cast. And the same material (aluminum alloy). One opening of each hollow space is an EGR gas inlet, and the other opening of each hollow space is an EGR gas outlet. And when EGR gas is distribute | circulated through each hollow space, this EGR gas is heat-exchanged with the cooling fluid in a water jacket, and is cooled.

Japanese Patent Laying-Open No. 2004-278342 (see FIGS. 4 and 7, paragraphs 0034-0037) Japanese Patent Laying-Open No. 2011-252441 (see FIGS. 1 to 5 and paragraphs 0030-0032) JP 2011-1111938 A (refer to FIGS. 1 to 4 and paragraphs 0037-0040)

  In the above-mentioned Patent Document 1, the cylinder head is only provided with the second in-head passage composed of a single through hole having a circular cross section, and thus the cooling performance is insufficient.

  In Patent Documents 2 and 3, since a plurality of EGR passages are provided in the cylinder head, sufficient cooling performance is exhibited as compared with Patent Document 1.

  However, in the case of the above-mentioned Patent Document 2, since the EGR passage member is separated from the cylinder head, the manufacturing cost increases, such as assembling work. In the case of the above-mentioned patent document 3, since the EGR passage is integrated with the cylinder head, it does not require assembling work as in the above-mentioned patent document 2.

  Further, in the case of Patent Document 2, since the EGR passage member that forms the EGR passage is a press-moldable metal material (for example, iron-based metal), the partition portion of the EGR passage is made of an aluminum alloy as in Patent Document 3. Compared with the case where it is, the weight increases and there is a concern that the heat exchange action between the EGR gas and the coolant is inferior.

  As described above, even in Patent Document 3, which is superior to Patent Document 2, since the cross-sectional shape of the EGR passage is comb-shaped, the end of the EGR gas introduction pipe communicated with the EGR passage When the shape of the portion and the end portion of the EGR gas discharge passage are circular in cross section, the EGR gas is introduced into the comb-shaped EGR passage at the time of introduction of the EGR gas into the EGR passage. It is considered that the rate of collision with the end face is increased, and there is a concern that the flow rate of the EGR gas introduced into the EGR passage may be reduced.

  In view of such circumstances, the present invention provides a cylinder head provided integrally with an EGR passage for cooling a part of engine exhaust gas (EGR gas) and introducing it to the engine intake side. The purpose of this is to make it possible to improve the cooling efficiency of the EGR gas of the inside as much as possible.

  The present invention is a cylinder head integrally provided with an EGR passage for cooling a part of the exhaust gas of the engine and introducing it to the engine intake side, and the EGR passage is provided in the cylinder head. It is installed in the vicinity of the water jacket, and in this EGR passage, in the intermediate region excluding the exhaust gas inlet side and the exhaust port side, there are a plurality of distribution spaces partitioned by the partition wall portion of the cylinder head. They are provided adjacent to each other, and the center of the introduction port and the center of the discharge port are offset.

  In this configuration, since a plurality of circulation spaces are partitioned and provided in the EGR passage, the wall portion that divides each circulation space is made of the same material as the cylinder head, and the surface area of the wall portion is equal to the EGR passage. Compared to the case where the interior is a single space. Thereby, the heat exchange efficiency of the exhaust gas (EGR gas) circulated through the EGR passage is improved as compared with the case where the inside of the EGR passage is a single space, so that the cooling performance of the EGR gas is improved.

  Moreover, although the intermediate region of the EGR passage is widened by providing a plurality of distribution spaces in the EGR passage, the introduction port side and the discharge port side in the EGR passage are offset and arranged. When the EGR gas flows in from the inlet side, the EGR gas flows in a substantially dispersed manner without flowing in the wide intermediate region.

  Preferably, the introduction port side can be arranged at a position closer to the water jacket than the discharge port side.

  In this case, since the introduction port side of the EGR passage is brought close to the water jacket of the cylinder head, the high temperature EGR gas introduced into the introduction port is quickly cooled, thereby improving the heat exchange efficiency.

  Preferably, the intermediate region can be set wider than the introduction port side and the discharge port side, and the connecting portion from the introduction port and the discharge port to the intermediate region includes the introduction port side and It can be set so as to gradually become wider from the discharge port side toward the intermediate region.

  In this configuration, the exhaust gas flowing from the introduction port side is easily dispersed from the intermediate region toward the discharge port side.

  Preferably, the partition wall portion in the EGR passage may be provided with a communication passage for communicating adjacent circulation spaces with the partition wall portion therebetween.

  In this configuration, part of the EGR gas flowing through the plurality of distribution spaces flows into the adjacent distribution space through the communication path. As a result, after the inflowing part of the EGR gas flows in, it comes to collide with or touch the wall portion constituting the adjacent circulation space, whereby the heat of the EGR gas easily moves to the wall portion. As a result, the heat exchange efficiency is further improved.

  Preferably, the circulation space may have a long hole shape that is long in a direction orthogonal to the circulation direction of the exhaust gas.

  With this configuration, it is possible to increase the surface area of the entire inner surface of each circulation space while maintaining a large cross-sectional area of each circulation space in the EGR passage. This makes it possible to increase the heat exchange efficiency while reducing the pressure loss (flow resistance) of the EGR gas.

  Further, if the EGR passage and the plurality of flow spaces are simultaneously formed using a sand core at the time of casting the cylinder head, the molten metal into the casting mold flows relatively smoothly. The shape quality of the EGR passage and the plurality of distribution spaces is improved.

  The cylinder head according to the present invention can improve the cooling efficiency of the EGR gas in the EGR passage as much as possible.

It is a front view showing a schematic structure of an engine provided with a cylinder head concerning one embodiment of the present invention. It is an arrow view of the (2)-(2) line cross section of FIG. FIG. 3 is a cross-sectional view taken along line (3)-(3) in FIG. 2. It is an enlarged view used in order to demonstrate the distribution | circulation form of EGR gas in the EGR channel | path of FIG. It is a figure which shows the EGR channel | path of the cylinder head which concerns on other embodiment of this invention, and is a figure corresponding to FIG. It is a front view which shows schematic structure of an engine provided with the cylinder head which concerns on further another embodiment of this invention.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. In the figure, 1 indicates the entire engine.

  The engine 1 is an in-line multi-cylinder engine (in this embodiment, a four-cylinder engine). The cylinder block 2 of the engine 1 is provided with a cylinder bore 2a, and the cylinder head 3 mounted on the cylinder block 2 is provided with a recess 3a constituting a part of the combustion chamber corresponding to the cylinder bore 2a. It has been. An intake pipe 4 is attached to the intake port 3b of the cylinder head 3 so as to communicate therewith, and an exhaust pipe 5 is attached to the exhaust port 3c of the cylinder head 3 so as to communicate therewith. The exhaust pipe 5 is provided with a catalytic converter 6.

  A water jacket 3d is provided inside the cylinder head 3 as shown in FIG. The water jacket 3d is provided at a predetermined position from the front end side (one end side in the combustion chamber arrangement direction 100) to the rear end side (the other end side in the combustion chamber arrangement direction 100) of the cylinder head 3. The coolant in the water jacket 3d is flowed by a cooling pump (not shown).

  The engine 1 is provided with an exhaust gas recirculation device (reference number omitted). This exhaust gas recirculation device lowers the combustion temperature in the combustion chamber of the engine 1 by introducing a part of the exhaust gas (EGR gas) discharged into the exhaust pipe 5 into the intake pipe 4 and mixing it with the intake air. To reduce nitrogen oxides.

  Specifically, the exhaust gas recirculation device includes an extraction pipe 11, an EGR passage 12, an introduction pipe 13, an EGR valve 14, and the like.

  The extraction pipe 11 extracts a part of the exhaust gas from the downstream side of the catalytic converter 6 in the exhaust pipe 5 and introduces it into the EGR passage 12 in the cylinder head 3.

  The EGR passage 12 is provided integrally inside the cylinder head 3 and introduces the EGR gas introduced from the take-out pipe 11 into the intake pipe 4 through the introduction pipe 13 and the EGR valve 14. Can be cooled by the coolant flowing through the water jacket 3d of the cylinder head 3.

  The introduction pipe 13 introduces EGR gas discharged from the EGR passage 12 of the cylinder head 3 into the intake pipe 4.

  The EGR valve 14 is installed in a communication connection portion between the EGR passage 12 and the introduction pipe 13, and controls the amount of EGR gas discharged from the EGR passage 12 to the introduction pipe 13 and the intake pipe 4.

  Next, the EGR passage 12 will be described in detail with reference to FIGS.

  As shown in FIGS. 1 and 2, the EGR passage 12 is arranged in the cylinder head 3 at one end side in the combustion chamber arrangement direction 100 (or one end side in the longitudinal direction, specifically, the front end side of the cylinder head 3). It is provided so as to open toward both ends of the direction along a direction (or short direction) orthogonal to the direction 100.

  The EGR passage 12 is installed in a form in which the exhaust gas flow direction 200 is substantially parallel to the coupling surface between the cylinder head 3 and the cylinder block 2. In addition to this, as shown in FIG. 1, since the engine 1 is mounted on the vehicle in a state where the engine 1 is inclined at a predetermined angle, the EGR passage 12 extends in the horizontal direction from the inlet 12a side to the outlet 12b side. And tilted upward.

  As shown in FIG. 2, the EGR passage 12 is installed in the vicinity of a water jacket 3 d provided in the cylinder head 3.

  In the EGR passage 12, the dimension in the combustion chamber arrangement direction 100 of the intermediate region 12c from the inlet 12a side to the outlet 12b side is set to be larger than that of the inlet 12a side and the outlet 12b side.

  As shown in FIGS. 2 and 4, the introduction port 12 a side is offset at a position closer to the water jacket 3 d than the discharge port 12 b side.

  The dimensions in the combustion chamber arrangement direction 100 of the connecting portion from the inlet 12a and the outlet 12b to the intermediate region 12c are set to gradually increase from the inlet 12a and the outlet 12b to the intermediate region 12c.

  A plurality of partition wall portions 12d are provided in the intermediate region 12c of the EGR passage 12, and a plurality of partition wall portions 12d are adjacent to each other in the combustion chamber arrangement direction 100 in the intermediate region 12c by the partition wall portions 12d. A plurality of distribution spaces 21, 22, and 23 are provided.

  The circulation spaces 21 to 23 have a long hole shape elongated in a direction 300 (a direction along the central axis of the cylinder bore 2a) orthogonal to the exhaust gas circulation direction 200. For example, as shown in FIG. 3, the cross-sectional shape of the circulation spaces 21 to 23 is a vertically long oblong hole shape, but the shape is not particularly limited, and may be, for example, an oval shape. is there.

  As described above, when the plurality of distribution spaces 21 to 23 are partitioned in the EGR passage 12, the intermediate region 12c of the EGR passage 12 is widened, but the introduction port 12a side and the discharge port 12b side. Since the EGR gas flows in from the inlet 12a side, as shown in FIG. 4, the EGR gas flows in a distributed manner in each of the circulation spaces 21 to 23, respectively. , EGR gas does not flow in the wide intermediate region 12c.

  As shown in FIG. 3, the inlet 12a is arranged so as to overlap the circulation space 21 near the water jacket 3d in the plurality of circulation spaces 21, 22, 23 of the EGR passage 12, and the discharge port 12b is It arrange | positions so that it may overlap with the distribution space 23 furthest away from the water jacket 3d. As a result, the rate at which the EGR gas introduced from the inlet 12a collides with the outer peripheral wall of the EGR passage and the end face of the partition wall 12d is reduced, so that the flow rate of the EGR gas introduced into the EGR passage 12 is increased. Slowness is suppressed or prevented.

  As described above, in the embodiment to which the present invention is applied, the cylinder head 3 is configured to be able to cool the EGR gas. Therefore, an EGR gas cooler separate from the cylinder head 3 is installed outside the cylinder head 3. Equipment costs can be reduced by eliminating the necessity or making it possible to downsize and simplify an external EGR gas cooler.

  In addition, in this embodiment, since the plurality of circulation spaces 21 to 23 are provided in the EGR passage 12, the wall portion 12d that partitions each of the circulation spaces 21 to 23 is made of the same material as the cylinder head 3, In addition, the surface area of the partition wall 12d is larger than that in the case where the EGR passage 12 has a single space. As a result, the heat exchange efficiency of the exhaust gas (EGR gas) circulated through the EGR passage 12 is improved as compared with the case where the inside of the EGR passage 12 is a single space, so that the cooling performance of the EGR gas is improved. To do.

  Moreover, although the intermediate | middle area | region 12c of the said EGR channel | path 12 becomes wide by partitioning and providing the some distribution space 21-23 in the EGR channel | path 12, the introduction port 12a side and the discharge port 12b side are offset. Therefore, when the EGR gas flows in from the inlet 12a side, the EGR gas does not flow in the wide intermediate region 12c but flows in a substantially distributed manner. Moreover, since the introduction port 12a side of the EGR passage 12 is brought close to the water jacket 3d of the cylinder head 3, the high temperature EGR gas introduced into the introduction port 12a is quickly cooled. improves.

  Furthermore, in this embodiment, since the cross-sectional shape of the plurality of flow spaces 21 to 23 in the EGR passage 12 is, for example, a long hole shape as shown in FIG. 3, the cross-sectional area of each flow space 21 to 23 is kept large. However, the surface area of the entire inner surface of the EGR passage 12 can be increased. This makes it possible to increase the heat exchange efficiency while reducing the pressure loss (flow resistance) of the EGR gas.

  By the way, the EGR passage 12 and the plurality of circulation spaces 21 to 23 can be formed by using a sand core at the same time when the cylinder head 3 is cast. Therefore, the number of manufacturing steps can be reduced as compared with the case where the EGR passage 12 and the plurality of distribution spaces 21 to 23 are formed by separate processing, and the manufacturing cost of the cylinder head 3 can be reduced.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) In the above embodiment, the cylinder head 3 used in the in-line four-cylinder engine 1 is taken as an example, but the present invention is not limited to this, and the number of cylinders, the engine type, etc. are arbitrary. .

  (2) In the above embodiment, for example, as shown in FIG. 5, the plurality of partition wall portions 12d installed in the EGR passage 12 are connected to the circulation spaces 21 to 23 adjacent to each other with the partition wall portion 12d interposed therebetween. You may make it provide the communication path 24 for connecting.

  In this case, part of the EGR gas flowing through the plurality of distribution spaces 21 to 23 flows into the adjacent distribution spaces 21 to 23 through the communication path 24. As a result, the inflowing part of the EGR gas collides with or touches the walls (12d and the inner surface of the outer peripheral wall of the intermediate region 12c) constituting the distribution spaces 21 to 23 after the inflow. Since the heat of the EGR gas easily moves to the wall portion (12d and the inner surface of the outer peripheral wall portion of the intermediate region 12c), the heat exchange efficiency is further improved.

  (3) In the above embodiment, the EGR passage 12 is installed in such a manner that the exhaust gas flow direction is set substantially parallel to the coupling surface with the cylinder block 2 in the cylinder head 3. It is not limited. For example, as shown in FIG. 6, the EGR passage 12 can be installed in a form in which the height from the coupling surface to the discharge port 12b is set higher than the height from the coupling surface to the introduction port 12a.

  (4) In the above embodiment, an example is given in which the number of the circulation spaces 21 to 23 provided in the EGR passage 12 is three, but the present invention is not limited to this and is not illustrated. There can be two or more.

  The present invention can be suitably used for a cylinder head in which an EGR passage for cooling a part of engine exhaust gas (EGR gas) and introducing it to the engine intake side is integrally provided.

1 engine
3 Cylinder head
3a Cylinder head recess (part of combustion chamber)
3c Cylinder head exhaust port
3d cylinder head water jacket
4 Intake pipe
5 exhaust pipe 11 take-out pipe 12 EGR passage 12a EGR passage introduction port 12b EGR passage discharge port 12c middle region of EGR passage 12d partition wall portion 13 introduction pipe 14 EGR valve 21-23 distribution space

Claims (5)

A cylinder head provided integrally with an EGR passage for cooling a part of the exhaust gas of the engine and introducing it to the engine intake side;
The EGR passage is installed in the vicinity of a water jacket provided in the cylinder head,
In the EGR passage, in the intermediate region excluding the exhaust gas inlet side and the exhaust port side, a plurality of flow spaces partitioned by a partition wall portion of the cylinder head are provided adjacent to each other,
A cylinder head, wherein the center of the inlet and the center of the outlet are offset. The cylinder head according to claim 1,
The cylinder head according to claim 1, wherein the introduction port side is disposed at a position closer to the water jacket than the discharge port side. The cylinder head according to claim 1 or 2,
The intermediate region is set wider than the introduction port side and the discharge port side,
The connecting portion from the inlet and the outlet to the intermediate region is set so as to gradually increase from the inlet and the outlet to the intermediate region. . In the cylinder head according to any one of claims 1 to 3,
The cylinder head according to claim 1, wherein the partition wall portion in the EGR passage is provided with a communication passage for communicating adjacent circulation spaces with the partition wall portion therebetween. In the cylinder head according to any one of claims 1 to 4,
The cylinder head according to claim 1, wherein the circulation space has a long hole shape that is long in a direction orthogonal to the flow direction of the exhaust gas.

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