JPH0224947Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an intake system for an engine.

(Prior Art) Conventionally, in order to facilitate fine adjustment of the idle speed of an engine, an intake passage equipped with a throttle valve is provided with a bypass passage that bypasses the throttle valve. An adjusting screw for adjusting the flow rate is arranged, and the adjusting screw adjusts the flow rate of the intake air introduced into the engine side through the bypass passage, thereby finely adjusting the idle speed of the engine. (For example, see Japanese Utility Model Application Publication No. 58-86448).

However, the idle speed of the engine can be finely adjusted by providing a bypass passage in the intake passage that bypasses the throttle valve and adjusting the flow rate of intake air flowing through the bypass passage using an adjuster screw. However, due to the following reasons, during long-term use, the idling speed gradually decreases from the initial set value, making the engine more likely to stall.

In other words, when the air-fuel mixture burns in the intake passage due to backfire during engine operation, or when part of the exhaust gas is recirculated (EGR) into the intake passage for the purpose of exhaust gas purification (NOx countermeasures). In this case, the combustion gas containing carbon also flows into the bypass passage, but in this case, the passage area of the bypass passage, especially the adjusting screw portion, is very narrow. Carbon in the combustion gas gradually adheres to and accumulates on the parts, and the passage area gradually decreases, resulting in the engine's idle speed gradually decreasing from the set speed originally set by the adjuster screw. It is.

(Purpose of the invention) The present invention is an attempt to improve the problems pointed out in the above-mentioned section of the prior art. The purpose of this is to maintain the rotational speed at a set rotational speed over a long period of time.

(Means for Achieving the Object) The present invention provides, as a means for achieving the above object, an intake passage provided with a throttle valve, which bypasses the throttle valve and directs intake air to the intake downstream side of the throttle valve. In the engine intake system, which is provided with a bypass passage for introducing the intake air and an intake air flow rate adjusting means in the bypass passage, the air intake passage is connected to the intake downstream opening of the bypass passage from the intake downstream end of the opening. A buff-full plate is attached that protrudes inward and bends from the downstream side of the intake air to the upstream side of the intake air.

(Function) In the present invention, by using the above-mentioned means, the inflow of combustion gas that flows back into the intake passage into the bypass passage is suppressed by the flow blocking action of the baffle plate, so that the amount of carbon deposited on the intake flow rate adjusting means is reduced. As much as possible, the decrease in the passage area of the bypass passage (i.e., the bypass intake air flow rate) due to the carbon adhesion is prevented for a long period of time.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 3.

(: Structure) FIG. 1 shows the main parts of the intake system of an automobile engine equipped with an intake device according to an embodiment of the present invention. This is the engine body. An intake manifold 5 is connected to the intake port 4 of the cylinder head 3, and a surge tank 6 is connected to the intake upstream end of the intake manifold 5.

Furthermore, the intake inlet side end surface 6a of the surge tank 6
A throttle body 10 having an intake passage 12 extending therethrough is connected to the throttle body 10 . A throttle valve 11 is installed in an intake passage 12 of the throttle body 10. The throttle body 10 also includes a bypass passage 1 having a small passage area that bypasses the throttle valve 11 and allows the upstream and downstream sides of the throttle valve 11 to communicate with each other.
3 is formed. This bypass passage 13 is
As shown in an enlarged view in FIG. 2, an upstream opening 1 opens at a position upstream of the throttle valve 11 of the intake passage 12.
3A, a downstream opening 13B that opens downstream of the throttle valve 11, and an intermediate passage 13C that connects the upstream opening 13A and the downstream opening 13B. Further, the intermediate passage section 13C is connected to the first passage section 14A which is continuous with the upstream opening section 13A and has a relatively small passage area.
and a second passage section 1 that is continuous with the first passage section 14A and has a larger passage area than the first passage section 14A.
4B, and the second passage portion 14B and the second passage portion 14B.
a third passage part 14C having a smaller passage area than the passage part 14B; and a third passage part 14 located between the third passage part 14C and the downstream opening 13B;
The fourth passage section 14D, which has a passage area larger than C, is composed of four parts having sequentially different passage areas.

Further, the upstream opening 13A of the bypass passage 13 is provided with a needle valve-shaped adjustment screw 15 (intake flow rate adjustment within the scope of the claims for utility model registration) for variably adjusting the passage area of the upstream opening 13A. ) is screwed on. In addition, bypass passage 1
The intake downstream end 1 of the intake downstream opening 13B of No. 3
3Ba faces the intake downstream end surface 10a of the throttle body 10.

Throttle body 10 having the configuration as described above
is bolted to the surge tank 6 with its intake downstream end face 10a abutting the intake inlet end face 6a of the surge tank 6. In order to apply this, a pair of gaskets 25, 25 are interposed between the sandwiching plate 2 and the intake inlet end face 6a of the surge tank 6 and the intake downstream end face 10a of the throttle body 10.
0 is installed. As shown in FIG.
The notch hole 22 has a notch hole 22 that can overlap and communicate with the intake passage 12 of No. and a bent tongue-shaped buttful plate 21 consisting of a tip portion 21b extending from the base portion 21a in a direction substantially perpendicular to the plane direction of the clamping plate 20.
is formed.

As shown in FIG. 2, the clamping plate 20 is installed with the tip 21a of the buffle plate 21 facing upstream of the intake air, and with the buffle plate 21 facing the downstream opening 13B of the bypass passage 13. It is being Therefore, the upper part and the part facing the intake downstream side of the downstream opening 13B of the bypass passage 13 are surrounded by the baffle plate 21, so that the intake passage of the throttle body 10 can be opened from the surge tank 6 side. A series of passages leading to the intake downstream opening 13B via the passage 12 are curved passages with high flow resistance. That is, the baffle plate 21 suppresses the combustion gas G flowing back from the surge tank 6 side to the throttle body 10 side from flowing into the bypass passage 13 side.

In addition, in FIG. 1, numeral 7 is an injector, and 8
is an air hose that connects the throttle cylinder 10 and an air cleaner (not shown).

(: Operation and its effect) When the engine is operated, intake air A is taken into the intake manifold 5 side through the throttle valve 11, mixed with fuel injected from the injector 7 side, and then stored in the working chamber 1a of the engine. be burned.

Further, fine adjustment of the idle speed of the engine is performed by adjusting the bypass passage 13 using the adjustment screw 15.
This is done by adjusting the flow rate of intake air introduced into the engine by adjusting the area of the passage.

On the other hand, when the air-fuel mixture concentration becomes diluted or the ignition timing is delayed, a so-called backfire occurs in which the air-fuel mixture burns in the intake passage 12, and the combustion gas G flows from the intake manifold 5 through the surge tank 6. Throttle body 1
0 (the same applies to the EGR gas).

In this case, when the combustion gas G flowing back to the intake passage 12 side flows from the intake passage 12 into the bypass passage 13, the carbon contained in the combustion gas G is transferred by the adjusting screw 15 to the bypass passage 13. A large amount is deposited on the upstream opening 13A of the bypass passage 13, which has a narrowed area, or on the valve head 15a of the adjusting screw 15, and the effective passage area of the bypass passage 13 is reduced by the adjusting screw 1.
5, the idle speed of the engine decreases from the preset value, and as a result, the idle speed of the engine decreases from the initially set value, making it more likely that the engine will stall, as described above (see the section on prior art). It is.

However, in this embodiment, since the present invention is applied and the buffle plate 21 is attached to the downstream opening 13B of the bypass passage 13, the flow inhibiting effect of the buffle plate 21 causes the throttle body to be removed from the surge tank 6 side. A part of the combustion gas G flowing back to the bypass passage 13 is prevented from flowing into the bypass passage 13 as much as possible. For this reason, the bypass passage 13
The adhesion of carbon to the vicinity of the upstream opening 13A of the adjusting screw 15 or to the valve head 15a of the adjusting screw 15 is suppressed as much as possible.
The passage area of the bypass passage 13 set by is maintained at the initially set value for a long period of time. Therefore, the idle speed of the engine is maintained at the initially set value for a long period of time, and the occurrence of engine stalling due to a decrease in the idle speed is prevented.

Furthermore, in this embodiment, the intermediate passage section 13C of the bypass passage 13 is divided into four sections having sequentially different passage areas, namely, a first passage section 14A having a small passage area and a second passage section 14B having a large passage area. Since the third passage section 14C has a small passage area and the fourth passage section 14D has a large passage area, a part of the combustion gas G flows through the bypass passage 13 despite the backflow prevention effect of the buff-full plate 21. Even when the combustion gas G flows into the downstream opening 13B, the flow energy is absorbed as the combustion gas G is repeatedly expanded and compressed while flowing from the fourth passage part 14D to the first passage part 14A. The backflow toward the adjuster screw 15 is suppressed as much as possible. Therefore, in this embodiment, a higher level of prevention of combustion gas backflow is achieved due to the synergistic effect of the backflow prevention action of the combustion gas G by the buff-full plate 21 and the absorption and relaxation action of gas flow energy in the intermediate passage portion 13C. It is effective.

(Effects of the invention) The engine intake system of the invention includes a bypass passage in the intake passage provided with the throttle valve for bypassing the throttle valve and introducing intake air to the intake downstream side of the throttle valve. , in an engine intake system in which an intake flow rate adjusting means is provided in the bypass passage, the intake downstream opening of the bypass passage is provided with an intake downstream end that protrudes into the intake passage from an intake downstream end of the opening; This device is characterized by being equipped with a buttful plate that bends toward the upstream side of the intake air.

Therefore, according to the engine intake system of the present invention, since the combustion gas that flows back into the intake passage is suppressed from flowing into the bypass passage, the amount of carbon adhering to the intake flow rate adjusting means can be reduced. The decrease in the passage area of the bypass passage (i.e., the bypass intake flow rate) due to the adhesion of carbon is prevented over a long period of time, and as a result,
The effect is that the idle speed of the engine is maintained at the set speed for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an intake system of an automobile engine equipped with an intake device according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion of FIG. 1, and FIG. It is an arrow view. 1...Engine body, 2...Cylinder block, 3...Cylinder head, 4...Intake port,
5... Intake manifold, 6... Surge tank, 7... Injector, 10... Throttle body, 11... Throttle valve, 12... Intake passage, 13... Bypass passage, 15... Adjustment screw, 20... ...pinching plate, 21...buttful board, 25...patchkin.

Claims (1)

[Scope of utility model registration request] An engine in which a bypass passage for bypassing the throttle valve and introducing intake air to the intake downstream side of the throttle valve is provided in an intake passage provided with a throttle valve, and an intake flow rate adjusting means is provided in the bypass passage. In the intake device, a bent full plate is provided at the intake downstream opening of the bypass passage, protruding from the intake downstream end of the opening into the intake passage, and bent from the intake downstream to the intake upstream. An engine intake system characterized in that the engine is equipped with a.