JP2017180334A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an EGR passage from backflowing due to condensation of oil floating in a surge tank, with a simple structure.SOLUTION: Inside a surge tank 2, an end pipe 9 constituting a terminal part of an EGR passage 8 is inserted. The end pipe 9 is inclined so as to become higher toward its tip, and an oil pitfall 19 is drilled at its middle part. Even when oil droplets flow into the end pipe 9, in the middle of flowing through an inner surface of the end pipe 9, the oil droplets drop from the oil pitfall 19 to the inside of the surge tank 2. Consequently, flow of EGR gas is not obstructed, and also miscibility of EGR gas and suctioned air is not deteriorated.SELECTED DRAWING: Figure 2

Description

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

  In an internal combustion engine such as a gasoline engine, in order to purify exhaust gas and improve fuel efficiency, it is widely performed to recirculate a part of exhaust gas to an intake system. The passage through which the EGR gas flows is called an EGR passage, and an EGR valve for controlling the flow rate is inserted in the middle of the passage.

  The EGR valve is, for example, a needle type. However, if oil adheres to the valve body or the rod, the movement becomes worse, and if it is severe, control becomes impossible. On the other hand, the end portion of the EGR passage viewed from the flow direction of the EGR gas often faces the surge tank, and the EGR gas is often diffused into the surge tank. In this case, blow-by gas is often dissipated in the surge tank, so that oil may be floating inside the surge tank. If this happens, the oil will condense into oil droplets and flow back through the EGR passage. Therefore, the movement of the EGR valve may be inhibited.

  With respect to this point, in Patent Document 1, when the EGR valve is already installed in the surge tank, a bowl-shaped partition wall covering the outlet of the EGR valve is provided so as to face the flow direction of the intake air. It is disclosed that EGR gas is ejected in the same direction as the flow of intake air.

Actual opening and closing No. 5-17148

  Patent Document 1 is a type in which an EGR gas injection port is provided on the wall of a surge tank, and it can be said that the reverse flow of oil into the EGR valve can be blocked by a bowl-shaped partition. However, in Patent Document 1, since the EGR gas is suddenly redirected by the partition wall and flows along the inner surface of the surge tank, not only the pressure loss is large, but it is unavoidable that the mixing property of the EGR gas and the intake air is deteriorated. I can't say that.

  This invention makes it a subject to improve such a present condition.

The present invention is
The end portion of the EGR passage having the EGR valve is composed of an end pipe that enters the inside of the surge tank, and the end pipe is inclined at least partially in the direction of the EGR gas flow. An oil pit that opens downward is provided in the inclined portion of the end pipe.
It is the composition.

  In the present invention, it is only necessary to make an oil drop hole with a downward opening in the pipe, and an inclined tongue piece covering the hole can be formed so as to protrude in the flow direction of the EGR gas. .

  In this invention, since the end pipe which comprises the termination | terminus part of an EGR channel | path has entered the inside of a surge tank, it can dissipate EGR gas to the strong flow of intake air. For this reason, the mixing property of intake air and EGR gas is remarkably improved. As a result, EGR gas can be distributed to each cylinder, which can contribute to the stability of combustion.

  Even if the oil component floating inside the surge tank aggregates and penetrates into the end pipe and flows as oil droplets along the inner surface of the end pipe, the oil droplets face down on the inclined portion of the end pipe. It drops into the inside of the surge tank from the hole or flows through the outer surface of the pipe after exiting the end pipe, and does not flow to the EGR valve.

  Furthermore, even if a hole is made in the pipe, the flow of EGR gas is not hindered, so there is no problem that the pressure loss is increased. Eventually, according to the present invention, it is possible to prevent a malfunction such that oil droplets flow backward through the EGR passage and cause malfunction of the EGR valve while ensuring a proper flow of EGR gas and high mixing with intake air.

It is a partially broken top view of 1st Embodiment. (A) is a sectional view taken along the line II-II in FIG. 1 taken along the EGR passage, and (B) is a bottom view of the pipe. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. It is a principal part enlarged view. It is a figure which shows other embodiment.

(1). First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic partial plan view of an internal combustion engine. An intake manifold 3 integrally provided with a surge tank 2 is fixed to an intake side surface 1 a of a cylinder head 1. The intake manifold 3 is a resin product and has a hollow structure formed by joining a plurality of members.

  The internal combustion engine of the present embodiment has three cylinders, and therefore, three branch pipes 4 are integrally connected to the surge tank 2 of the intake manifold 3. Each branch pipe 4 is connected to two flanges 5, and the flanges 5 are fixed to the intake side surface 1 a of the cylinder head 1. The branch pipe 4 extends from the lower surface of the surge tank 2 and is curved toward the cylinder head 1 after being largely curved. An intake intake 6 is provided on the upper surface of the surge tank 2, and a throttle valve (not shown) is fixed to the intake intake 6.

  The surge tank 2 has a relief hole 7 that overlaps the intake side surface 1 a of the cylinder head 1, and an end pipe 9 that constitutes the EGR passage 8 enters the inside of the surge tank 2 from the relief hole 7. The end of the end pipe 9 is slightly closer to the group of branch pipes 4 than the central part of the surge tank 2 and opens sideways. Since the intake air flows downward into the bottom of the surge tank 2, the EGR gas is exposed to a strong intake air flow. As a result, the intake air and the EGR gas are mixed evenly.

  In the vicinity of the rear end surface 1 c of the cylinder head 1, as a component of the EGR passage 8, the rear end surface is in communication with the first EGR hole 10 opened to the exhaust side 1 b of the cylinder head 1 and the first EGR hole 10. A valve mounting hole 11 opened in 1c and a second EGR hole 12 opened toward the intake side surface 1a are formed. The first EGR hole 10 and the valve mounting hole 11 have the same height, and the second EGR hole 12 is located below the first EGR hole 10 and the valve mounting hole 11, and the valve mounting hole 11 and the second EGR hole 12. Are communicated with each other through the vertically communicating hole 13.

  As shown in FIG. 3, the casing 15 of the EGR valve 14 is fitted in the valve mounting hole 11. The EGR valve 14 is a type that opens and closes the inside of the casing 15 with a needle valve 16, and the needle valve 16 is controlled by a motor 17. An intermediate portion of the casing 15 communicates with the second EGR hole 12 through the communication hole 13, and the amount of EGR gas passing is controlled by the back and forth movement of the needle valve 16. The EGR gas is guided to the first EGR hole 10 by another pipe.

  The second EGR hole 12 opens in a portion corresponding to the escape hole 7 of the intake manifold 3 on the intake side surface 1 a of the cylinder head 1. As shown in FIG. 2B, a substantially small bracket plate 18 is welded to the base end portion of the end pipe 9, and the bracket plate 18 is fixed to the intake side surface 1a with screws (not shown). ing.

  As shown in FIG. 2, the end pipe 9 as a whole is inclined so that its height gradually increases toward the tip when viewed from the crank axis direction. The tip is open sideways.

  An oil drop hole 19 opened downward is formed in an intermediate portion between the tip of the end pipe 9 and the bracket plate 18. In the example of FIG. 4B, a tongue piece 20 that covers the oil dropping hole 19 from above is formed.

  In the above configuration, when the oil component floating inside the surge tank 2 aggregates and enters the end pipe 9, the oil droplets flow downward along the bottom surface inside the end pipe 9. Since the oil drop hole 19 is opened, the oil droplet flows down from the oil drop hole 19 and drops into the surge tank 2 or flows along the lower surface of the outer periphery of the end pipe 9 toward the cylinder head 1. . In any case, the oil droplet does not move from the end pipe 9 to the location of the EGR valve 14 via the second EGR hole 12. For this reason, malfunction of the EGR valve 14 is not caused.

(2). Other Embodiments FIG. 4 shows another embodiment. Among these, in the example shown to (A), the tongue piece 20 is provided under the flow path. In this example, since the discharge of the oil droplet is guided by the tongue piece 20, the oil droplet is surely discharged. There is no action at all, and the branching of the EGR gas to the oil pit 19 is also suppressed.

  In the example shown in (B), a stepped portion 21 is bent in the middle of the end pipe 9 and an oil dropping hole 19 is formed in the stepped portion. In this example, the oil drop is more reliably discharged because the drop of the oil drop is stopped by the stepped portion 21. Since the end pipe 9 is slightly bent, the flow of the EGR gas is not hindered.

  In the example shown in (C), an enlarged diameter portion 22 is formed in the middle of the end pipe 9, and an oil dropping hole 19 is formed in the enlarged diameter portion 22. Also in this example, since the oil droplets are reliably prevented from flowing down by the enlarged diameter portion 22, the oil droplets are completely discharged. Further, since the inner diameter is not restricted, the flow of EGR gas is not hindered at all.

  As mentioned above, although several examples of embodiment of this invention were demonstrated, this invention can be variously embodied besides the above. For example, the present invention can be applied to a structure in which the entire EGR passage 8 is constituted by a pipe without providing an EGR hole in the cylinder head 1 and the end portion (downstream end portion) of the end pipe 9 is inserted into the surge tank.

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

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Surge tank 3 Intake manifold 6 Intake inlet 7 Escape hole 8 EGR passage 9 End pipe which comprises the terminal part of EGR passage 10 1st EGR hole 12 2nd EGR hole 14 EGR valve 19 Oil drop hole

Claims (1)

The end portion of the EGR passage having the EGR valve is composed of an end pipe that enters the inside of the surge tank, and the end pipe is inclined at least partially in the direction of the EGR gas flow. An oil pit that opens downward is provided in the inclined portion of the end pipe.
Internal combustion engine.

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