JP4394991B2 - EGR device for internal combustion engine - Google Patents

Description

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

  In an internal combustion engine such as an automobile engine, as shown in Patent Document 1, an engine equipped with an EGR device that allows a part of exhaust gas to flow into an intake system in order to reduce combustion temperature and reduce NOx generation amount is put into practical use. Has been. A specific configuration of such an EGR apparatus is shown in FIGS. FIG. 11 is a schematic view of the periphery of the cylinder head of the internal combustion engine as viewed from the side, and FIG. 12 is a schematic view of the periphery of the cylinder head as viewed from above.

  In the internal combustion engine shown in these drawings, air is taken in from an intake manifold 51 that constitutes an intake system, and exhaust gas after fuel combustion is discharged through an exhaust manifold 52 that constitutes an exhaust system.

The EGR device includes an EGR passage 53 that allows exhaust gas passing through the exhaust manifold 52 to flow into the intake system as EGR gas, and a valve unit 56 that adjusts the amount of EGR gas that flows to the intake system through the EGR passage 53. The EGR passage 53 is formed in a cylinder head 54 of the internal combustion engine, a distribution plate 55 sandwiched between the cylinder head 54 and the intake manifold 51, and the like. The distribution plate 55 is for distributing EGR gas to each cylinder of the internal combustion engine. Further, the valve unit 56 receives the inflow of EGR gas from the EGR passage 53 a of the cylinder head 54 and flows the same gas into the EGR passage 53 b of the distribution plate 55, and the flow rate of EGR gas flowing through the gas passage 57. And an EGR valve (not shown) whose opening is adjusted to adjust the angle. The amount of EGR gas flowing from the gas passage 57 to the EGR passage 53b of the distribution plate 55, that is, the amount of EGR gas flowing to each cylinder is adjusted through the adjustment of the opening degree of the EGR valve.
Japanese Patent Laid-Open No. 2002-339809

  Incidentally, in Patent Document 1, the valve unit 56 is attached to the side surface of the distribution plate 55 on the intake manifold 51 side as shown in FIG. 11, and the EGR passage 53a of the cylinder head 54 is connected to the connection passage 58 formed in the distribution plate 55. To the gas passage 57 of the valve unit 56. The valve unit 56 is attached to the distribution plate 55 by adjusting the flow rate of the EGR gas in the EGR passage 53 as close as possible to the intake system and adjusting the inflow amount of the EGR gas to the intake system with high responsiveness. Because.

  However, when the valve unit 56 is attached to the distribution plate 55 as described above, the unit 56 has a left-right dimension of the cylinder head 54 (a portion between the end on the intake manifold 51 side and the end on the exhaust manifold 52 side), It will be in the state which protruded to the intake manifold 51 side. For this reason, it is inevitable that the overall size of the internal combustion engine is increased, and this leads to a lower degree of freedom when the engine is mounted on an automobile or the like.

  The present invention has been made in view of such circumstances, and an object of the present invention is to prevent the valve unit from being mounted outside the dimensions of the cylinder head and increasing the size of the internal combustion engine. It is an object to provide an EGR device for an internal combustion engine.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, there is provided an EGR passage through which the exhaust gas of the engine flows into the intake system in the cylinder head of the internal combustion engine and the distribution plate sandwiched between the cylinder head and the intake manifold. An internal combustion engine comprising a valve unit provided with a gas passage for receiving exhaust gas from the EGR passage of the cylinder head and flowing the exhaust gas to the EGR passage of the distribution plate and an EGR valve for adjusting the amount of exhaust gas flowing through the gas passage. In the engine EGR device, a recess is provided in a portion of the cylinder head facing the distribution plate, and the recess and the distribution plate are spaced apart from each other by a space where the valve unit can be sandwiched between the surfaces facing each other . Forming fixed surfaces and disposing the valve unit between the fixed surfaces to both the fixed surfaces. Constant to, it matches the valve unit in the right and left dimension of the cylinder head.

According to the above configuration, the valve unit is housed between the recess of the cylinder head and the distribution plate and fixed to the fixed surface. For this reason, the valve unit is mounted in a state where it fits within the left and right dimensions of the cylinder head (the part from the end on the intake manifold side to the end on the exhaust manifold side) . The valve unit is mounted outside the dimensions. Accordingly, it is possible to avoid an increase in the overall size of the internal combustion engine.

  According to a second aspect of the present invention, in the first aspect of the present invention, the distribution plate is formed long along the arrangement direction of each cylinder of the internal combustion engine, and is sandwiched between the cylinder head and the intake manifold. Part, a unit mounting part that is positioned on the end side in the longitudinal direction of the sandwiching part and the fixing surface is formed, and is located between the sandwiching part and the unit mounting part so as to bend more easily than the clamping part. The gist is to include a flexible portion.

  The distance between the fixed surfaces of the cylinder head (recess) and the distribution plate varies slightly depending on the dimensional error of the cylinder head and the distribution plate. Further, the width of the portion of the valve unit that is sandwiched between the two fixed surfaces also varies slightly due to the dimensional error of the valve unit. When the width of the portion sandwiched between the two fixed surfaces of the valve unit becomes shorter than the distance between the two fixed surfaces, the unit mounting portion of the distribution plate is pulled toward the cylinder head side with the mounting of the valve unit. When the width of the portion sandwiched between the two fixed surfaces of the valve unit is longer than the distance between the two fixed surfaces, the unit mounting portion of the distribution plate is pushed away from the cylinder head as the valve unit is mounted. Thus, when a force toward the cylinder head side or a force away from the cylinder head acts on the unit mounting portion, if the clamping portion of the distribution plate is bent by the force, the space between the clamping portion and the cylinder head Alternatively, gas may leak from between the clamping portion and the intake manifold. However, according to the above configuration, when the force as described above is applied to the unit mounting portion, the flexible portion positioned between the unit mounting portion and the sandwiching portion bends, thereby preventing the valve from being bent. The difference between the width of the portion sandwiched between the two fixed surfaces of the unit and the distance between the two fixed surfaces is absorbed. For this reason, it can suppress that gas leak arises with the bending of a clamping part.

  According to a third aspect of the present invention, in the second aspect of the present invention, the flexible portion may be bent in a direction in which the fixing surface of the unit mounting portion approaches or separates from the fixing surface of the cylinder head. The gist is that it is more likely to occur.

  Due to the difference between the width of the portion sandwiched between the two fixed surfaces of the valve unit and the distance between the two fixed surfaces, the force acting on the unit mounting portion of the distribution plate during mounting of the valve unit causes the fixing surface of the unit mounting portion to This works in a direction to approach and separate from the fixed surface of the cylinder head (recess). According to the above configuration, since the bending in the direction is more likely to occur in the flexible portion than in the holding portion, the flexible portion is reliably bent in the above direction when the force is applied, and the holding portion is bent. Can be suppressed.

Hereinafter, an embodiment in which the present invention is embodied in an EGR device for an automobile engine will be described with reference to FIGS.
FIG. 1 is a schematic view of the periphery of a cylinder head of an engine to which the EGR device of this embodiment is applied as viewed from the side, and FIG. 2 is a schematic view of the periphery of the cylinder head as viewed from above. In this engine, an intake manifold 1 constituting an intake system and an exhaust manifold 2 constituting an exhaust system are attached to a cylinder head 3. The engine EGR device also includes an EGR passage 4 for flowing exhaust gas passing through the exhaust manifold 2 as EGR gas to the intake system, and a valve unit 5 for adjusting the amount of EGR gas flowing to the intake system through the EGR passage 4. ing.

  The EGR passage 4 is formed in the cylinder head 3 and a distribution plate 6 sandwiched between the cylinder head 3 and the flange 1 a of the intake manifold 1. This distribution plate 6 is for distributing EGR gas to each cylinder of the engine, and is formed long along the cylinder arrangement direction (vertical direction in FIG. 2) of the engine, and is flanged by a plurality of bolts 7. It is attached to the cylinder head 3 together with 1a (intake manifold 1). These bolts 7 pass through the flange 1 a and the distribution plate 6 and are screwed into the cylinder head 3. Then, by tightening each bolt 7, the distribution plate 6 is fixed to the cylinder head 3 while being sandwiched between the cylinder head 3 and the flange 1 a.

  The valve unit 5 accepts inflow of EGR gas from the EGR passage 4 a of the cylinder head 3, adjusts the flow rate of the EGR gas flowing through the gas passage 8 flowing through the EGR passage 4 b of the distribution plate 6 and the gas passage 8. An EGR valve 9 whose opening is adjusted as appropriate is provided. The amount of EGR gas that flows from the gas passage 8 to the EGR passage 4b of the distribution plate 6, that is, the amount of EGR gas that flows to each cylinder is adjusted by adjusting the opening degree of the EGR valve 9.

Next, the mounting structure of the valve unit 5 will be described.
A recess 12 that is recessed in a direction away from the one end (left direction in the figure) is provided in a portion of the cylinder head 3 that faces the one end in the longitudinal direction of the distribution plate 6. Then, fixed surfaces 10 and 11 are formed on the mutually opposing surfaces of the recess 12 and one end of the distribution plate 6 with a space where the valve unit 5 can be sandwiched, respectively. Of these fixed surfaces 10 and 11, an EGR passage 4a of the cylinder head 3 is opened in the fixed surface 10 on the recess 12 side, and an EGR passage 4b on the distribution plate 6 side is formed on the fixed surface 11 on the one end side. Is open.

  The valve unit 5 is housed between the fixed surfaces 10 and 11 and fixed to the fixed surfaces 10 and 11 by a plurality of bolts 13 (only two are shown in FIG. 2). That is, these bolts 13 penetrate the distribution plate 6 (one end portion) and the valve unit 5 and are screwed into the cylinder head 3 (the fixing surface 10 of the recess 12). By tightening each bolt 13, the valve unit 5 is fixed to both the fixing surfaces 10 and 11 while being sandwiched between the cylinder head 3 and the distribution plate 6. When the valve unit 5 is attached, the EGR passage 4 a of the cylinder head 3 and the EGR passage 4 b of the distribution plate 6 are connected to the gas passage 8 of the valve unit 5.

  By attaching the valve unit 5 in this way, the valve unit 5 can be accommodated in the left and right dimensions of the cylinder head 3 (the portion between the end on the intake manifold 1 side and the end on the exhaust manifold 2 side). Therefore, it can be avoided that the physique of the engine increases as the valve unit 5 protrudes from the dimensions and is mounted on the engine, and the degree of freedom when the engine is mounted on the automobile is reduced.

Next, a specific structure of the distribution plate 6 will be described with reference to FIG.
FIG. 3 is a side view of the distribution plate 6. The distribution plate 6 includes various parts such as a clamping part 6a, a unit attaching part 6b, and a flexible part 6c, which will be described in detail below.

[Holding part 6a]
The clamping portion 6 a is fixed to the cylinder head 3 with bolts 7 while being sandwiched between the cylinder head 3 and the flange 1 a of the intake manifold 1. A plurality of through holes 14 through which the bolts 7 pass, a plurality of air holes 15 for allowing air taken into each cylinder of the engine to pass through, and an EGR passage 4b are formed in the clamping portion 6a. The EGR passage 4 b communicates with each air hole 15, and EGR gas flows through each cylinder through the supply of EGR gas from the EGR passage 4 b to the air hole 15.

[Unit mounting portion 6b]
The unit mounting portion 6b is located at one end in the longitudinal direction of the distribution plate 6 and at the end in the longitudinal direction relative to the sandwiching portion 6a, and the fixing surface 11 for fixing the valve unit 5 is formed thereon. The unit mounting portion 6b is formed with a plurality of through holes 16 through which the bolts 13 pass, and an EGR passage 4b and an opening 17 thereof. The opening 17 of the EGR passage 4b is for connecting the gas passage 8 of the unit 5 and the EGR passage 4a on the cylinder head 3 side when the valve unit 5 is attached.

[Flexible part 6c]
The flexible portion 6c is located between the sandwiching portion 6a and the unit mounting portion 6b and is more easily bent than the sandwiching portion 6a. The flexible portion 6c is formed in a cylindrical shape that can pass through the EGR passage 4b and has a minimum necessary thickness for ensuring strength, and thus has a smaller diameter than the sandwiching portion 6a. It has a shape. By forming the flexible portion 6c in such a shape, the flexible portion 6c is bent more easily than the sandwiching portion 6a.

Here, the effect by providing the flexible part 6c in the distribution plate 6 is demonstrated based on the comparison with the case where the flexible part 6c is not provided.
As shown in FIG. 4, the valve unit 5 is housed between the fixed surface 10 of the cylinder head 3 and the fixed surface 11 of the distribution plate 6. The width W of the portion sandwiched between the two fixed surfaces 10 and 11 of the valve unit 5 varies depending on the dimensional error. That is, the distance X is slightly changed by the dimensional error of the cylinder head 3 (recess 12) and the distribution plate 6 (unit mounting portion 6b), and the width W is slightly changed by the dimensional error of the valve unit 5. It will change.

  When the width W becomes shorter than the distance X due to a dimensional error, the unit mounting portion 6b is drawn toward the cylinder head 3 with the tightening of the bolt 13 for mounting the valve unit 5. On the other hand, when the width W is longer than the distance X, the unit mounting portion 6b is pushed away from the cylinder head 3 as the unit 5 is accommodated between the fixed surfaces 10 and 11 for mounting the valve unit 5. It is. When a force toward the cylinder head 3 (hereinafter referred to as force F1) or a force away from the cylinder head 3 (hereinafter referred to as force F2) acts on the unit mounting portion 6b in this manner, If the bending part 6c is not provided, the clamping part 6a may bend and gas leakage may occur.

  FIG. 5 shows that when the flexible portion 6c is not provided, the force F1 to the cylinder head 3 side acts on the unit mounting portion 6b due to the mounting of the valve unit 5 in a state where the width W is shorter than the distance X. This shows how the distribution plate 6 bends. The force F1 acts in the direction in which the fixed surface 11 of the unit mounting portion 6b is brought closer to the fixed surface 10 of the cylinder head 3. In this case, the bending due to the force F1 acting on the unit mounting portion 6b extends to the clamping portion 6a as indicated by a two-dot chain line, and the clamping portion 6a and the cylinder head 3 are caused by the bending of the clamping portion 6a. There is a risk that gas will leak from between the two or between the clamping portion 6a and the flange 1a of the intake manifold 1.

  On the other hand, when the flexible part 6c is provided in the distribution plate 6, when the force F1 acts on the unit attaching part 6b, the flexible part 6c located between the unit attaching part 6b and the clamping part 6a. Will bend as shown by a two-dot chain line in FIG. This is because the flexible portion 6c has a smaller diameter than the sandwiching portion 6a and is more easily bent than the sandwiching portion 6a in the direction in which the force F1 acts. Thus, by bending the flexible part 6c, the difference between the width W and the distance X can be absorbed without bending the clamping part 6a. Accordingly, it is possible to suppress the occurrence of gas leakage with the bending of the sandwiching portion 6a.

  FIG. 7 shows that when the flexible portion 6c is not provided, the force F2 in the direction away from the cylinder head 3 to the unit mounting portion 6b due to the mounting of the valve unit 5 in a state where the width W is longer than the distance X. This shows how the distribution plate 6 bends when is acted upon. Note that the force F2 acts in a direction in which the fixed surface 11 of the unit mounting portion 6b is separated from the fixed surface 10 of the cylinder head 3. In this case, the bending due to the force F2 acting on the unit mounting portion 6b extends to the clamping portion 6a as indicated by a two-dot chain line, and the clamping portion 6a and the cylinder head 3 are caused by the bending of the clamping portion 6a. There is a risk that gas will leak from between the two or between the clamping portion 6a and the flange 1a of the intake manifold 1.

  However, in this case as well, by providing the flexible portion 6c on the distribution plate 6, when the force F2 acts on the unit mounting portion 6b, the flexible portion 6c is indicated by a two-dot chain line in FIG. 8 for the same reason as described above. Therefore, the difference between the width W and the distance X can be absorbed without bending the clamping portion 6a. Accordingly, it is possible to suppress the occurrence of gas leakage with the bending of the sandwiching portion 6a.

According to the embodiment described in detail above, the following effects can be obtained.
(1) Avoiding a reduction in the degree of freedom when mounting the engine in a car as the valve unit 5 protrudes from the left and right dimensions of the cylinder head 3 and is mounted on the engine. Can do.

  (2) When the forces F1 and F2 are applied, the flexible portion 6c of the distribution plate 6 can be bent so that the holding portion 6a does not bend. Therefore, the holding portion is bent along with the bending of the holding portion 6a. Gas can be prevented from leaking between 6a and the cylinder head 3 or between the sandwiching portion 6a and the flange 1a.

  (3) The flexible portion 6c has a smaller diameter than the clamping portion 6a, and the direction in which the forces F1 and F2 act, that is, the fixing surface 11 of the unit mounting portion 6b is fixed to the cylinder head 3. It is easy to bend in the direction of approaching / separating from the surface 10. For this reason, when said F1, F2 acts, the flexible part 6c can be reliably bent in said direction, and it can suppress that the clamping part 6a bends.

  (4) The distribution plate 6 does not need to be provided with the conventional connection passage 58 (see FIGS. 11 and 12). For this reason, it is not necessary to ensure the sealing performance at both ends of the connection passage 58, and the cost can be reduced accordingly.

In addition, the said embodiment can also be changed as follows, for example.
-You may change the flexible part 6c into the other shape which is more flexible than the clamping part 6a. In this case, the flexible part 6c is shaped to be more easily bent than the clamping part 6a in at least the direction in which the forces F1 and F2 are applied. Examples of such shapes are shown in FIGS. 9 is a side view of the distribution plate 6, and FIG. 10 is a cross-sectional view of the distribution plate 6 of FIG. 9 viewed from the direction of the arrow AA. In the examples shown in these drawings, the width of the flexible portion 6c in the above direction is the clamping portion 6a so that the flexible portion 6c can be easily bent in the direction in which the forces F1 and F2 are applied (vertical direction in FIG. 10). The flexible portion 6c is formed so as to be smaller than that.

  -The difference between the distance X between the fixed surfaces 10 and 11 and the width W of the valve unit 5 is suppressed to such an extent that the above-described gas leakage does not occur, for example, the cylinder head 3 and the valve unit 5 are formed with high accuracy with respect to their dimensions. If possible, the distribution plate 6 is not necessarily provided with the flexible portion 6c.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic which looked around the cylinder head of the engine to which the EGR apparatus of this embodiment is applied from the side. Schematic view of the cylinder head and its surroundings as viewed from above. The side view which shows the detailed structure of the distribution plate in an EGR apparatus. The schematic diagram which shows the attachment state of the valve unit in an EGR apparatus. The schematic diagram which shows the bending of the distribution plate accompanying the valve unit attachment in case the flexible part is not provided in the distribution plate. The schematic diagram which shows the bending of the distribution plate accompanying valve unit attachment at the time of providing a flexible part in a distribution plate. The schematic diagram which shows the bending of the distribution plate accompanying the valve unit attachment in case the flexible part is not provided in the distribution plate. The schematic diagram which shows the bending of the distribution plate accompanying valve unit attachment at the time of providing a flexible part in a distribution plate. The side view of the distribution plate which shows the other example of a flexible part. Sectional drawing which looked at the distribution plate of FIG. 9 from the arrow AA direction. Schematic view of the surroundings of the cylinder head of an engine employing a conventional valve unit mounting structure as seen from the side. Schematic view of the cylinder head as viewed from above.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Intake manifold, 1a ... Flange, 2 ... Exhaust manifold, 3 ... Cylinder head, 4 (4a, 4b) ... EGR passage, 5 ... Valve unit, 6 ... Distribution plate, 6a ... Nipping part, 6b ... Unit attaching part, 6c ... flexible part, 7 ... bolt, 8 ... gas passage, 9 ... EGR valve, 10, 11 ... fixed surface, 12 ... recess, 13 ... bolt, 14 ... through hole, 15 ... air hole, 16 ... through hole , 17 ... opening.

Claims (3)

An EGR passage is formed in the cylinder head of the internal combustion engine and a distribution plate sandwiched between the cylinder head and the intake manifold to flow the exhaust of the engine to the intake system, and the exhaust is received from the EGR passage of the cylinder head. In an EGR device for an internal combustion engine comprising a gas passage through which exhaust gas flows through an EGR passage of the distribution plate and a valve unit provided with an EGR valve for adjusting the amount of exhaust gas flowing through the gas passage.
A recess is provided in a portion of the cylinder head facing the distribution plate, and a fixing surface is formed on the surface where the recess and the distribution plate are opposed to each other with an interval between which the valve unit can be sandwiched. An EGR device for an internal combustion engine, wherein the valve unit is disposed between the fixed surfaces and fixed to both the fixed surfaces , and the valve unit is accommodated within the left and right dimensions of the cylinder head . The distribution plate is formed long along the arrangement direction of the cylinders of the internal combustion engine, and is located between the cylinder head and the intake manifold, and on the end side in the longitudinal direction from the clamping portion. The EGR device for an internal combustion engine according to claim 1, further comprising: a unit mounting portion on which the fixing surface is formed; and a flexible portion that is located between the clamping portion and the unit mounting portion and is more flexible than the clamping portion. . 3. The EGR of the internal combustion engine according to claim 2, wherein the flexible portion is more likely to bend in a direction in which the fixing surface of the unit mounting portion approaches and separates from the fixing surface of the cylinder head than the clamping portion. apparatus.

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