JP2009091925A - Engine exhaust recirculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a cooling performance of recirculating exhaust gas in an engine exhaust recirculating device, in which a part of the exhaust recirculating path is formed inside a cylinder head. <P>SOLUTION: An upstream side of the exhaust recirculating path having an EGR valve 6 in the middle is formed by an EGR pipe 4 that communicates with an exhaust system and is connected with a flange portion 3b of an exhaust manifold 3 on the side of the cylinder head 11. A mid-stream side of the exhaust recirculating path is formed by an internal passage portion 11b of the cylinder head 11 and a groove portion 11a at a joining face with the flange portion 3b. The EGR valve 6 is provided in a downstream side of the exhaust recirculating path. An end portion of the EGR pipe 4 in the upstream side of the exhaust recirculating path protrudes into the cylinder head 11 beyond the flange portion 3b. The groove portion 11a in the mid-stream side of the exhaust recirculating path corresponding to the protruding portion has a recessed portion 11e having a passage space around the protruding portion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation apparatus for an engine that recirculates a part of exhaust gas to an intake system from an exhaust system attached to a liquid-cooled engine main body through an exhaust gas recirculation path having an exhaust control valve interposed therebetween.

  An exhaust gas recirculation device (also referred to as an EGR device) that reduces the NOx content in exhaust gas mainly by reducing the combustion temperature in the combustion chamber of the engine is widely known. In general, this exhaust gas recirculation device is provided with an EGR passage connecting an exhaust passage and an intake passage, and a part of the exhaust gas passing through the exhaust passage is recirculated from the intake passage to the combustion chamber via the EGR passage.

  In such an exhaust gas recirculation device, when a part of the exhaust gas is recirculated in recent years, high-temperature recirculated exhaust gas (EGR gas) has a thermal effect on the intake manifold or the temperature of the combustion chamber rises. In order to suppress this, a dedicated EGR cooler is provided to lower the temperature of the EGR gas.

  Further, as a configuration for lowering the temperature of the EGR gas, instead of providing an EGR cooler, an EGR passage is formed in the end side of the cylinder head of the engine, and cooling is performed when the EGR gas passes through the EGR passage. The thing which made it do is proposed (refer patent document 1).

  That is, in the conventional structure disclosed in Patent Document 1 below, the EGR gas passing through the EGR passage is cooled by using the action of the coolant flowing through the cylinder head.

Japanese Patent Laid-Open No. 11-210576

  As described above, the conventional structure disclosed in Patent Document 1 has an advantage that the EGR gas can be cooled without providing a special cooling means such as an EGR cooler. However, on the other hand, in recent years, there has been a strong demand for further improving the cooling performance of EGR gas.

  An object of the present invention is to provide an exhaust gas recirculation device for an engine in which a part of the exhaust gas recirculation path is formed in a cylinder head and the cooling performance of the exhaust gas recirculation gas can be further improved.

  An exhaust gas recirculation device for an engine according to the present invention recirculates part of exhaust gas to an intake system from an exhaust system attached to a liquid-cooled engine main body through an exhaust gas recirculation path having an exhaust control valve interposed therebetween. The upstream side of the exhaust gas recirculation path is formed by a pipe member communicating with the exhaust system and is connected to a flange portion on the cylinder head side of the exhaust manifold, while the midstream side of the exhaust gas recirculation path is a cylinder head The exhaust passage is provided on the downstream side of the exhaust gas recirculation path, and the end of the pipe member on the upstream side of the exhaust gas recirculation path. Projecting into the cylinder head beyond the flange, and the groove on the midstream side of the exhaust gas recirculation path corresponding to the projection is recessed with a flow path space around the projection. Those having.

  According to this configuration, since a part of the exhaust gas recirculation path can be formed effectively long in the cylinder head, it is possible to ensure a long time for the recirculated exhaust gas to pass through the exhaust gas recirculation path, and thereby the recirculation by the coolant. Exhaust gas cooling performance can be improved.

  In an embodiment of the present invention, the middle flow side of the exhaust gas recirculation path is provided on the end cylinder side of the cylinder head, the exhaust control valve is provided on an end surface portion of the engine body, and the downstream side of the exhaust gas recirculation path. At least a part of the side includes the internal passage portion of the cylinder head.

  According to this configuration, it is possible to cool the recirculated exhaust gas not only on the midstream side but also on the downstream side using the space on the end cylinder side of the cylinder head, thereby further improving the cooling performance of the recirculated exhaust gas. Can be made.

  In one embodiment of the present invention, an upstream end portion of the pipe member is connected to the flange portion so as to protrude into the cylinder head, and the cylinder head is connected to the flange portion. A second groove portion that communicates with the exhaust port of the specific cylinder is provided on the mating surface, and the second groove portion has a recess with a flow path space around the protruding portion of the pipe member.

  According to this configuration, the exhaust gas recirculation path can be secured longer by forming a recess not only in the downstream end portion of the pipe member but also in the upstream end portion. Further improvement can be achieved.

  In one embodiment of the present invention, the groove portion on the midstream side of the exhaust gas recirculation path is provided on one end cylinder side of the cylinder head, and the second groove portion is the other end cylinder of the cylinder head. The pipe member has both ends projecting into the groove portions and connected to the flange portion of the exhaust manifold.

  According to this configuration, it is possible to improve the cooling performance of the recirculated exhaust gas while further effectively using the space in the cylinder block.

  In one embodiment of the present invention, a water jacket for allowing a coolant to flow is formed in the cylinder head, and an end portion of the pipe member defines the recess and the water jacket inside the cylinder head. The cylinder block is opened so as to face the wall surface of the cylinder block.

  According to this configuration, most of the recirculated exhaust gas flowing into the recess from the pipe member can collide with the wall surface whose surface temperature has fallen the most due to the coolant in the water jacket, so that the cooling performance of the recirculated exhaust gas is further improved. Can be made.

  According to the present invention, since the exhaust gas recirculation path in the cylinder head can be formed effectively long, the cooling performance of the recirculated exhaust gas by the coolant can be enhanced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing an engine structure equipped with an exhaust gas recirculation apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged horizontal sectional view showing a portion of a cylinder head in which an EGR passage is formed. . The engine main body 1 shown in FIG. 1 is a liquid-cooled four-cylinder engine. The engine main body 1 is connected to the downstream end of an intake passage (not shown) by an intake manifold 2 constituting an intake system. The upstream end of an exhaust passage (not shown) is connected by an exhaust manifold 3 constituting the exhaust system.

  The intake manifold 2 and the exhaust manifold 3 are formed with four branch passages 2a, 2a,..., 3a, 3a,... That individually communicate with the four cylinders 1a, 1b, 1c, and 1d of the engine. The upstream side portions of the passages 2a, 2a,..., 3a, 3a,... Are gathered and communicated with the intake passage and the exhaust passage, respectively.

  The cylinder head 11 constituting the engine body 1 is provided with intake ports 12a to 12d and exhaust ports 13a to 13d corresponding to the cylinders 1a to 1d, respectively, and the branch passages 2a and 2a of the intake manifold 2 are respectively provided. ,... Are connected to the branch passages 3a, 3a,.

  Although not shown, the cylinder head 11 is provided with on-off valves that define a combustion chamber by closing, corresponding to the intake ports 12a to 12d and the exhaust ports 13a to 13d.

  In the intake ports 12a to 12d, intake air is introduced into the combustion chamber from the intake passage via the intake manifold 2 by opening the open / close valve, and in the exhaust ports 13a to 13d, the exhaust manifold is opened by opening the open / close valve. Exhaust gas is discharged from the combustion chamber via 3.

  Incidentally, the exhaust manifold 3 is formed with a flange portion 3b (see FIG. 2) as a mating surface when joined to the cylinder block 11, and this flange portion 3b communicates with the downstream end side of the exhaust manifold 3. The EGR pipe 4 is connected. One end of the EGR pipe 4 protrudes into the EGR passage 5 formed in the cylinder head 11 beyond the flange portion 3b as shown in FIG.

  The EGR passage 5 is formed by a groove portion 11a formed on a mating surface with the flange portion 3b of the cylinder head 11, and an internal passage portion 11b continuous with the groove portion 11a. The downstream side of the EGR passage 5 is an engine The main body 1 is connected to an EGR valve 6 disposed on the end surface portion.

  The EGR valve 6 is connected to an EGR passage 7 formed by an internal passage portion 11 c in the cylinder head 11, and the EGR pipe 4 is connected via the EGR valve 6 by the two EGR passages 5 and 7. It is connected to the intake manifold 2.

  In this embodiment, the above-described EGR pipe 4 and EGR passages 5 and 7 form an exhaust gas recirculation path that constitutes an upstream portion, a midstream portion, and a downstream portion, and the above-described EGR valve 6 is interposed downstream thereof. It has a structure like this.

  Therefore, a part of the exhaust gas passing through the exhaust passage can be circulated through the EGR pipe 4 as EGR gas, and the EGR gas that has circulated through the EGR pipe 4 passes through the EGR passages 5 and 7 and the intake manifold 2. Thus, it can be recirculated to a combustion chamber (not shown) of the engine body 1. The EGR valve 6 adjusts the flow rate of EGR gas flowing through the exhaust gas recirculation path by electronic control of a control unit (not shown).

  By the way, a water jacket 11d as shown in FIG. 2 is formed around a portion forming the combustion chamber of the cylinder head 11, and this water jacket 11d is a cooling liquid (for example, cooling) for cooling the portion. A coolant passage through which water is circulated.

  For this reason, the EGR gas that has passed through the EGR pipe 4 is cooled by the action of the coolant in the water jacket 11d when passing through the EGR passage 5, as indicated by the arrow A indicated by the thick broken line in FIG.

  And in this embodiment, the groove part 11a corresponding to the protrusion part of the EGR pipe 4 has the hollow part 11e in the surroundings of the said protrusion part, leaving the flow-path space recessed in the water jacket 11d side.

  Thus, when the EGR gas flows from the EGR pipe 4 into the EGR passage 5, the EGR gas behaves so as to circulate along the peripheral wall of the recessed portion 11e as shown in the drawing. In other words, the recess 11e can effectively form a part of the exhaust gas recirculation path in the cylinder head 11, thereby ensuring a long time for the EGR gas to pass through the exhaust gas recirculation path, and for special cooling such as an EGR cooler. Even if no means is used, it is possible to improve the cooling performance of the water jacket 11d only by the coolant.

  In the present embodiment, the EGR passage 5 is formed on the end cylinder 1a side of the cylinder head 11 to form the midstream portion of the exhaust gas recirculation path, and the EGR valve 6 is disposed on the end surface portion of the engine body 1. A part on the downstream side of the exhaust gas recirculation path is configured to include the EGR path 7 in the cylinder head 11. For this reason, the EGR gas can be cooled not only in the EGR passage 5 but also in the EGR passage 7 on the downstream side by utilizing the space on the end cylinder 1a side of the cylinder head 11, and the cooling performance of the EGR gas is further improved. This can be further improved.

  Moreover, in this embodiment, the EGR pipe 4 is opened in the hollow part 11e so that the wall surface of the cylinder block 11 which divides the hollow part 11e and the water jacket 11d may be opposed. For this reason, most of the EGR gas flowing from the EGR pipe 4 into the hollow portion 11e can be made to collide with the wall surface whose surface temperature has been lowered most by the coolant of the water jacket 11d, and the cooling performance of the EGR gas can be further improved. Can do.

  By the way, in embodiment shown in FIG. 1, FIG. 2, although the hollow part 11e was formed in the site | part corresponding to the downstream edge part of the EGR pipe 4, it was set as the structure which ensures the length of an exhaust gas recirculation path by this. However, the present invention is not necessarily limited to this.

  FIG. 3 is a plan view showing an engine structure equipped with an exhaust gas recirculation apparatus according to another embodiment of the present invention, and FIG. 4 is a horizontal sectional view of a cylinder head and an EGR pipe. In the present embodiment shown in FIGS. 3 and 4, the same components as those in the first embodiment described with reference to FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the embodiment shown in FIGS. 3 and 4, the downstream end portion of the EGR pipe 40 is connected to the flange portion 3b so as to protrude into the cylinder head 11 in the same manner as the EGR pipe 4 of the above-described embodiment. At the same time, the upstream end portion of the EGR pipe 40 is connected to the flange portion 3 b so as to protrude into the cylinder head 11.

  In the cylinder block 11, a second groove portion 11f communicating with the exhaust port 13d of the specific cylinder (here, the end cylinder 1d) is formed on the mating surface with the flange portion 3b, and an EGR passage 8 is formed.

  Further, the second groove portion 11f corresponding to the protruding portion of the EGR pipe 40 has a hollow portion 11g around the protruding portion with a channel space recessed toward the water jacket 11d side.

  With this configuration, in this embodiment, a part of the gas discharged from the specific exhaust port 13d circulates along the peripheral wall of the recess 11g as indicated by the arrow B indicated by the thick broken line in FIG. The EGR pipe 40 flows into the EGR pipe 40 while taking a proper behavior, and then returns to the intake manifold 2 via the EGR passages 5 and 7 as EGR gas.

  As described above, in the present embodiment, not only the downstream end portion of the EGR pipe 40 but also the upstream end portion of the EGR pipe 40 is formed with the recessed portion 11g, so that the exhaust gas recirculation path can be secured longer. Therefore, the cooling performance of the EGR gas can be further improved.

  Further, in the cylinder head 11, since the space between the intake ports 12a to 12d and the exhaust ports 13a to 13d is extremely narrow, the groove 11a is formed on the one end cylinder 1a side, Two groove portions 11f are formed on the other end cylinder 1d side.

  And both ends of the EGR pipe 40 protrude into the groove 11a and the second groove 11f, and both are connected to the flange 3b. For this reason, it is possible to improve the cooling performance of the EGR gas while further effectively using the space secured larger than between the ports.

  Incidentally, in both the first embodiment shown in FIGS. 1 and 2 and the other embodiments shown in FIGS. 3 and 4, the downstream side of the exhaust gas recirculation path is formed by the internal passage portion 11 c inside the cylinder block 11. However, the present invention is not necessarily limited to this. For example, a second EGR pipe may be provided between the EGR valve 6 and the intake manifold 2 so that they are connected outside the cylinder block 11.

  Moreover, in each embodiment mentioned above, although the engine main body 1 is set to inline 4 cylinder, inline 6 cylinder etc. may be sufficient. Moreover, not only an in-line cylinder but a V-type cylinder may be used.

In correspondence between the configuration of the present invention and the above-described embodiment,
The exhaust control valve of the present invention corresponds to the EGR valve 6,
Similarly,
The pipe member corresponds to the EGR pipes 4 and 40,
The present invention is not limited only to the configuration of the above-described embodiment, and many embodiments can be obtained.

The top view which shows the engine structure which mounts the exhaust gas recirculation apparatus which concerns on embodiment of this invention. The horizontal sectional view which expands and shows the site | part of the cylinder head in which the EGR channel | path was formed. The top view which shows the engine structure carrying the exhaust gas recirculation apparatus which concerns on other embodiment of this invention. The horizontal sectional view of a cylinder head and an EGR pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine main body 1a, 1b, 1c, 1d ... Cylinder 3 ... Exhaust manifold 3b ... Flange part 4, 40 ... EGR pipe 6 ... EGR valve 11 ... Cylinder head 11a ... Groove part 11b, 11c ... Internal passage part 11d ... Water jacket 11e , 11g ... hollow 11f ... second groove 13a, 13b, 13c, 13d ... exhaust port

Claims (5)

An exhaust gas recirculation device for an engine that recirculates a part of exhaust gas to an intake system from an exhaust system attached to a liquid-cooled engine body through an exhaust gas recirculation path having an exhaust control valve interposed therebetween,
The upstream side of the exhaust recirculation path is formed by a pipe member communicating with the exhaust system, and is connected to a flange portion on the cylinder head side of the exhaust manifold,
The midstream side of the exhaust gas recirculation path is formed by a groove portion of the mating surface of the cylinder head with the internal passage portion and the flange portion,
The exhaust control valve is provided downstream of the exhaust gas recirculation path,
The end of the pipe member on the upstream side of the exhaust gas recirculation path protrudes into the cylinder head beyond the flange,
The exhaust gas recirculation device for an engine, wherein the groove portion on the midstream side of the exhaust gas recirculation passage corresponding to the protrusion has a recess around the protrusion. A midstream side of the exhaust gas recirculation path is provided on an end cylinder side of the cylinder head;
The exhaust control valve is provided on an end surface portion of the engine body,
The exhaust gas recirculation device for an engine according to claim 1, wherein at least a part of the downstream side of the exhaust gas recirculation passage includes an internal passage portion of the cylinder head. The upstream end of the pipe member is connected to the flange portion so as to protrude into the cylinder head, and
The cylinder head is provided with a second groove portion communicating with the exhaust port of the specific cylinder on the mating surface with the flange portion,
The exhaust gas recirculation device for an engine according to claim 1 or 2, wherein the second groove portion has a recess with a flow path space around the protruding portion of the pipe member. A groove portion on the midstream side of the exhaust gas recirculation path is provided on one end cylinder side of the cylinder head,
The second groove is provided on the other end cylinder side of the cylinder head;
4. The exhaust gas recirculation device for an engine according to claim 3, wherein both ends of the pipe member project into respective groove portions and are connected to flange portions of the exhaust manifold. The cylinder head is formed with a water jacket for circulating the coolant,
5. The end of the pipe member opens in the cylinder head so as to face a wall surface of the cylinder block that partitions the depression and the water jacket. Engine exhaust gas recirculation device.

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