JPH04265462A - Intake piping structure - Google Patents

Abstract

PURPOSE:To prevent deposit adhesion to a throttle valve and facilitate maintenance of intake piping in an intake piping structure for returning a part of exhaust gas to an air intake system. CONSTITUTION:The inside peripheral part 7a of a gasket 5 inserted between a throttle body 1 and a surge tank 2 is formed so as to protrude inward from both inner walls 1a, 2a, so that it can catch and pile up deposit.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to exhaust gas recirculation (hereinafter referred to as
Some devices, such as EGR (hereinafter referred to as "EGR") and crankcase ventilation (hereinafter referred to as "PCV") devices, return part of the exhaust gas and blow-by gas, that is, engine exhaust gas, to the intake system. The present invention relates to an intake pipe structure for a device that attempts to reduce harmful substances (NO, unburned HC, etc.) contained in exhaust gas by mixed combustion with gas (NO, unburned HC, etc.).

0002

[Prior Art] When introducing the above-mentioned exhaust gas into the intake system, generally the exhaust gas and fresh air flowing through the throttle valve are mixed uniformly. It is installed on the downstream side and as close to the throttle valve as possible, so that the exhaust gas is well mixed by the turbulence of fresh air through the throttle valve, and is evenly distributed to each cylinder.

However, the intake pipe structure in which the exhaust gas inlet and the throttle valve are close to each other is strongly affected by intake backflow phenomena such as intake pulsation, and deposits adhere to the outer edge of the valve body of the throttle valve. There is a problem in that the outer edge of the valve body of the throttle valve is stuck to the inner wall of the intake pipe through deposits, resulting in poor valve operation.

In order to solve the above-mentioned problems, the present applicant first formed a protruding wall on the inner wall of the intake pipe between the inlet of the exhaust gas into the intake passage and the throttle valve, thereby reducing the intake air flow. An application has been filed for an intake pipe structure that attempts to protect the outer edge of the valve body of a throttle valve against backflow of
issue).

[0005]

The above-mentioned intake pipe structure is sufficiently effective in preventing deposits from forming on the throttle valve. However, in order to keep the area around the throttle valve clean, it is necessary to periodically clean and remove deposits that have accumulated on the protruding wall during use. Since it is formed integrally with the body, its removal is by no means easy and poses maintenance problems.

In addition, the above-mentioned intake pipe structure has a protruding wall portion formed in the throttle body near the throttle valve, and a joint between the throttle body and the intake pipe (for example, a surge tank) in which the exhaust gas inlet is provided. Since the part is on the intake downstream side (i.e. exhaust gas inlet side) of the protruding wall part, deposits tend to accumulate at the joint part, and eventually the throttle body and surge tank become stuck together, causing the above-mentioned problem. It may be difficult to remove the intake pipe during cleaning and removal.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide an intake pipe structure that can prevent deposits from forming on the throttle valve and is easy to maintain.

[0008]

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, engine exhaust gas is guided into the intake passage downstream of the throttle valve, thereby removing the exhaust gas mixed with fresh air. In the intake pipe structure of an internal combustion engine designed to cause re-combustion, the intake pipe joint located between the inlet of the exhaust gas into the intake passage and the throttle valve is provided with an inner wall of the intake pipe on the downstream side of the intake pipe from the joint. An intake pipe structure is provided that includes a gasket having an inner peripheral portion that projects inward.

[0009]

[Operation] When exhaust gas flows backward in the intake passage, deposits are deposited on the gasket, which has an inner circumferential portion that protrudes inward from the inner wall of the intake pipe, which is located on the downstream side of the intake pipe joint. Deposits do not adhere to the intake pipes on both sides (for example, the throttle body and surge tank), preventing them from sticking together.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows the intake pipe section near the throttle valve when, for example, exhaust gas recirculation gas (hereinafter referred to as EGR gas) is introduced into the intake system of an engine. In the figure, 1 is a component of the intake pipe. A throttle body, 2 is a surge tank that also constitutes an intake pipe and is adjacent to the throttle body 1, 3 is a throttle valve installed inside the throttle body 1, and 4 is an EGR that opens into the surge tank 2 on the intake downstream side of the throttle valve 3. Gas inlets are shown respectively. Therefore, in FIG. 1, the left side of the figure shows the intake upstream side, and the right side of the figure shows the intake downstream side.

According to this embodiment, in the intake pipe 1 constructed as described above, the EGR gas inlet 4 and the throttle valve 3 are connected to each other.
A gasket 5 is installed at the joint between the throttle body 1 and the surge tank 2 to provide an airtight seal between the two.

Unlike conventional gaskets, this gasket 5 is a so-called cap-shaped gasket in which a conventional flat gasket portion 6 and a cylindrical bush portion 7 are integrated, as shown in the figure. Its bushing part 7 is closely fitted to the inner wall 2a of the surge tank 2. Therefore, the inner peripheral part of this gasket 5, that is, the inner peripheral part 7a of the bushing part 7 is located inside the inner wall 2a of the surge tank 2 located downstream of the intake air from this gasket 5, and the bushing part 7 itself Similarly, the throttle body 1 is formed such that the inner circumferential portion 7a thereof protrudes inwardly from the inner wall 1a thereof.

Further, according to the present embodiment, the bush portion 7 is formed in a tapered shape such that the inner peripheral portion 7a thereof gradually decreases in inner diameter as it approaches the throttle body 1.
A plurality of grooves 8 are formed on its surface for deposit deposition.

The function of the gasket 5 described above will be explained. Generally, in an internal combustion engine, intake pulsation occurs within the intake pipe. This pulsation moves from the right side to the left side in FIG. 1, which is opposite to the so-called normal intake flow direction. Therefore, in an internal combustion engine equipped with an EGR device in which the exhaust gas inlet 4 is provided in the surge tank 2, carbon components and the like in the exhaust gas flow toward the throttle body 1 along with the pulsating flow.

However, according to this embodiment, as described above, the gasket 5 is disposed at the joint between the throttle body 1 and the surge tank 2, and the inner circumferential portion 7a
protrudes inward from the inner walls 1a and 2a of the throttle body 1 and the surge tank 2, so the exhaust gas directed toward the periphery of the throttle valve 3 comes into contact with this inner circumferential portion 7a and is formed on the inner circumferential portion 7a. The deposit d will be collected in the groove 8. Therefore, the deposit d is less likely to adhere around the throttle valve 3, and the valve is prevented from sticking.

According to this embodiment, the gasket 5 itself, which is sandwiched between the throttle body 1 and the surge tank 2, actively collects the deposit d due to its unique shape. Therefore, the deposit d does not adhere to both the throttle body 1 and the surge tank 2, and as a result, it is possible to prevent the deposit d from adhering to both the throttle body 1 and the surge tank 2.

The above-described intake pipe structure also has advantages from the viewpoint of maintenance. That is, according to this embodiment, since most of the deposits adhere to the gasket 5, in order to remove the deposits, the throttle body 1 and the surge tank 2 are separated and the gasket 5 is replaced with a new one. Alternatively, the gasket 5 itself may be cleaned, and the deposit removal operation becomes extremely easy.

Although the operation and effects of the present invention have been explained above with reference to one embodiment, the present invention is not limited to this embodiment. That is, for example, as shown in FIG. 2, the bushing portion 17 of the gasket 15 is fitted into the throttle body 1 side, and the inner peripheral portion 17a thereof is fitted onto the surge tank inner wall 2a.
The gasket 25 may be located further inward, or as shown in FIG. However, the gasket can collect the deposits and prevent them from forming across both parts.

[0019]

As explained above, according to the present invention, the inner circumferential portion of the gasket protrudes inward from the intake pipe, so that this portion collects deposits in the exhaust gas heading toward the throttle valve. It is possible to prevent the intake pipes located on both sides from sticking to each other, and maintenance is easy because deposits can be easily removed from the inside of the intake pipe by replacing or cleaning only the gasket.

[Brief explanation of the drawing]

FIG. 1 is an intake pipe sectional view showing an intake pipe structure as an embodiment of the present invention.

FIG. 2 is a sectional view of an intake pipe as a modified embodiment different from FIG. 1;

FIG. 3 is a sectional view of an intake pipe showing yet another embodiment.

[Explanation of symbols]

1...Throttle body 2...Surge tank 3...Throttle valve 4...Exhaust gas inlet 5, 15, 25...gasket 7a, 17a, 25a...Inner peripheral part d...Deposit

Claims (1)

[Claims] Claim 1. An intake pipe structure for an internal combustion engine in which engine exhaust gas is guided into an intake passage on the downstream side of the intake air from a throttle valve, so that the exhaust gas mixed with fresh air is combusted again. A gasket having an inner circumferential portion protruding inward from the inner wall of the intake pipe on the downstream side of the joint is provided at the intake pipe joint located between the gas inlet to the intake passage and the throttle valve. An intake pipe structure featuring