JPS6124685Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device for an internal combustion engine, and particularly to an exhaust gas recirculation device of a type that discharges recirculated exhaust gas into an intake passage formed by an intake manifold or the like.

Generally, in this type of exhaust gas recirculation system, when considering the distribution of recirculated exhaust gas to each cylinder, a flow control valve is provided on the throttle body side connected to the collector part of the intake manifold, and the exhaust gas is recirculated inside the collector in the vicinity. It is better to open the exhaust outlet of the passage.

However, due to layout considerations, there are cases where it is necessary to provide a flow control valve at the end of the collector opposite to the throttle body. In such a case, if the exhaust gas discharge port of the exhaust gas recirculation device is to be opened toward the throttle body side, it is necessary to form a long exhaust gas recirculation passage with a small diameter in the collector portion. However, in the conventional one-piece casting method using a sand core when casting the intake manifold, as mentioned above, the cast part has a small diameter and is long, resulting in deformation or falling off of the sand core, which reduces the yield. The problem was that it was extremely bad and costly.

Further, since the intake manifold is cooled by the intake air, the exhaust gas flowing in the exhaust gas recirculation passage is cooled, and highly corrosive condensed water adheres to the inner surface of the passage. Therefore, if the exhaust gas recirculation passage is formed long in this way, the cooling effect will be greater, and there is a risk that the conventional one will deteriorate more quickly due to corrosion (Utility Model Opening in 1983).
Publication No. 76422).

This idea was made in view of the above circumstances.
A collector part is formed to be horizontally elongated along the direction in which the cylinders are arranged, and the upstream end of the branch pipe is opened at intervals on the side wall along the longitudinal direction.A throttle body is provided on one side of the collector part, and a flow rate control valve is provided on the other side. In addition to providing an exhaust outlet in the collector section near the throttle body, the exhaust recirculation passage from the flow control valve to the exhaust outlet is integrally cast with a highly heat-resistant and corrosion-resistant pipe exposed along the inner wall of the collector section. An embodiment of the present invention will be described in detail below.

1 to 3, an intake manifold 4 is provided on the downstream side of a throttle body 3, which is provided with an intake throttle valve 2 whose opening and closing are controlled by a control lever 1, and forms an intake passage to an internal combustion engine. This intake manifold 4 includes a collector section 6 connected to the downstream end of the throttle body 3 and formed parallel to the cylinder head 5, and a branch pipe section 7 that branches independently from the collector section to each cylinder and is arranged at substantially equal lengths. Preparation, branch pipe section 7
It is fixed to the cylinder head 5 via a flange 8 at the tip with bolts or the like.

On the other hand, a flow control valve 11 screwed onto the intake manifold 4 via a gasket 10 is interposed in an exhaust gas recirculation passage 9 communicating with an exhaust passage (not shown). The flow rate control valve 11 is mounted as close as possible to the collector end opposite to the throttle body 3. At the downstream end of the exhaust gas recirculation passage 9 on the downstream side of the flow rate control valve 11, a pipe 12 made of a material with high heat resistance and corrosion resistance, such as stainless steel, is arranged along the inner wall of the collector section 6 and about half of it is exposed. It is formed by integrally casting into the collector part 6, and its tip opening, that is, the exhaust discharge port 13, is opened upstream of the branch pipe part 7 near the downstream of the throttle valve 2, and exhaust gas is discharged into the collector part 6. are doing.

The downstream end of the exhaust gas recirculation passage 9 is processed in the fourth step.
This will be described in more detail with reference to the figures. First, both ends of the pipe 12 are plugged with blind plugs 14 made of aluminum or the like to prevent cast metal from flowing in during casting. Said blind plug 1
4 may be an arm-shaped stopper, or may be closed by pressing the end of the pipe itself with a press. Next, this pipe 12
When the intake manifold 4 is cast, it is held integrally with the casting sand core forming the collector portion 6, and cast metal such as aluminum alloy is poured into a mold and cast together with the intake manifold 4. At this time, boss portions 15 and 16 are simultaneously formed at both ends and the middle portion of the pipe 12, respectively, in order to facilitate pipe holding and post-processing. In this way, the pipe 12 is attached to the collector section 6 (Fig. 4A
(see), then machined to create the exhaust recirculation passage 9.
Complete the downstream end. That is, the core hole 17 provided in the boss portion 15 is end-milled, and at the same time the blind plugs at both ends of the pipe 12 are scraped off to open both ends of the pipe 12, and the exhaust outlet 13 and flow control valve 11 protrude and communicate with the inside of the collector. A communicating hole 18 is formed by processing (see FIG. 4B). The communication hole 18
can be processed linearly by arranging the flow rate control valve 11 as close to the collector portion 6 as possible.

After these processes, a blind plug 19 is provided in the core hole 17 to complete the downstream end of the exhaust gas recirculation passage 9.

Therefore, due to the layout, the flow control valve 11 must be installed at the end of the collector section 6 on the opposite side from the throttle body 3, and the recirculated exhaust gas discharge port 13 must be installed upstream of the branch pipe section 7 near the throttle valve 2. In other words, when forming a small diameter and long exhaust gas recirculation passage in the intake manifold 4, the yield during casting is significantly improved and production costs can be reduced compared to the case where a passage hole is formed using a conventional core. . Of course, the thickness of the intake passage can be made thinner, which also leads to weight reduction. Furthermore, even if the recirculated exhaust gas is cooled through the pipe 12 and highly corrosive condensed water is generated, the pipe 12
Since the pipe 12 is made of a highly corrosion-resistant material, there is no fear that internal corrosion of the pipe 12 will increase the flow resistance to the recirculated exhaust gas. Furthermore, since the opening surface 13a of the exhaust outlet 13 is formed obliquely in the opposite direction to the throttle valve 2 in the intake air inflow direction, it is possible to prevent carbon, etc. in the exhaust gas from adhering to the throttle valve portion.

In addition, since the pipe 12 is integrally cast into the inner wall of the collector section 6, the pipe 12 can be held securely and vibrations of the pipe 12 caused by engine vibration can be prevented.

Incidentally, if an appropriate number of exhaust discharge ports are provided in the intermediate portion of the pipe 12, the distribution of the recirculated exhaust gas can be further improved.

As described above, according to the present invention, the collector part is formed to be horizontally elongated along the direction in which the cylinders are arranged, and the upstream end of the branch pipe part is opened at one side with intervals provided on the side wall along the longitudinal direction. A throttle body is provided, a flow control valve is provided on the other side, and an exhaust discharge port is provided in the collector section near the throttle body, and the exhaust gas recirculation passage from the flow control valve to the exhaust discharge port is constructed using a heat-resistant and corrosion-resistant pipe. Since the flow control valve is formed along the exposed inner wall of the collector section, even if the flow control valve must be mounted on the opposite side of the throttle body due to the layout and a long exhaust recirculation passage is required, the exhaust recirculation The passage is easy to form, and there is no need to increase the wall thickness of the intake manifold, and the intake manifold can be formed with almost no increase in weight. Furthermore, since the yield of casting is improved, productivity is improved and costs can be significantly reduced.

Furthermore, damage to the exhaust gas recirculation passage due to corrosion can be prevented, and changes in recirculation characteristics over time can be reduced.In addition, since the recirculated exhaust gas does not come into direct contact with the intake manifold, the temperature rise in the intake manifold due to exhaust heat is reduced, and the temperature of the fuel supply system is reduced. Since there is little rise, malfunctions such as vapor lock can be prevented. In addition, the pipe can be held securely, and damage to the exhaust gas recirculation passage due to vibration can be prevented, and no noise is generated.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway plan view showing one embodiment of the exhaust gas recirculation device according to the present invention, and Fig. 2 is a -
3 is a cross-sectional view taken from FIG. 1, FIG. 4 is an enlarged view of the boss portion of the collector that holds both ends of the pipe, A is a view before processing, and B is a view after processing. 4...Intake manifold, 6...Collector section, 7
... Branch pipe section, 9 ... Exhaust recirculation passage, 11 ... Flow rate control valve, 12 ... Pipe, 13 ... Exhaust discharge port.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine configured to recirculate exhaust gas to an intake passage through an exhaust gas recirculation passage equipped with a flow rate control valve, the intake passage is formed horizontally in the direction in which the cylinders are arranged, and is arranged at intervals on the side walls along the longitudinal direction of the cylinders. An intake passage collector section is provided in which the upstream end of the branch pipe section is opened, a throttle body is provided at one end of the collector section, the flow control valve is disposed at the other end, and an exhaust passage is provided near the throttle body of the collector section. A discharge port is formed, and the downstream end of the exhaust gas recirculation passage from the flow rate control valve to the exhaust discharge port is formed of a pipe with high heat resistance and corrosion resistance, and the pipe is exposed along the inner wall of the collector section. An exhaust gas recirculation device for an internal combustion engine, characterized in that the exhaust gas recirculation device is integrally cast into the internal combustion engine.