JPH0726540B2 - Engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention mainly relates to an intake system for a multi-cylinder engine for automobiles, which increases maximum output and maintains high output over a relatively wide operating speed range. The present invention relates to an intake device that can be used.

[Conventional technology]

Conventionally, in a multi-cylinder engine for automobiles, as a means for obtaining a high output, the intake pipe length is set to an optimum length, and the intake pipe length can be switched between long and short to obtain a high output over a wide operating speed range. Is being done.

In recent years, the demand has increased more and more, and since a high output is required from the low speed range close to the idling speed of the engine to the maximum rotation range, the intake pipe tends to be further lengthened. That is, the thick intake pipe corresponding to the high output is required to be set longer for adapting to the low speed, but it is difficult to accommodate it in a narrow engine compartment.

Further, although it has been practiced to provide two types of intake pipes for high speed and low speed (for example, Japanese Patent Laid-Open No. 58-10130), since each requires an air cleaner, they are housed in a similarly narrow engine compartment. Not only is it difficult, but it also hinders the ease of maintenance.

[Objects of the Invention, Means for Solving Problems]

The present invention has been made to alleviate the above-mentioned difficulties, and an object of the present invention is to make a small-sized intake device that is compatible with high-speed operation while using a relatively thick and long intake pipe. That is, the intake passage for each cylinder is drawn out from one side of the multi-cylinder type cylinder head to the side, inverted upward on the upstream side of the throttle valve and extended forward, and into the intake box provided near the cylinder head. In addition to opening the high-speed passages that are opened and closed by the secondary valve that opens in the high-speed region downstream of the reversal portion of the intake passage, the high-speed passages are opened, and the upstream ends of these high-speed passages are opened to a common intake chamber. The chamber is characterized in that it is connected to a portion on the downstream side of the throttle valve in each of the intake passages via an on-off valve that closes when the engine has a high output.

[Action]

Since the intake air is introduced into the combustion chamber through the thick and long intake pipe, a high output is obtained in the low speed operation range. Also, in the high-speed operating range, a high-speed passage that is connected almost linearly to the cylinder head is opened, and the reflected wave acts well on the intake pipe, so high high-speed output can be achieved without opening and closing a long intake pipe. Can be obtained together.

〔Example〕

The present invention will be described below with reference to the illustrated embodiment. In the drawing, reference numeral 1 denotes an engine body, which is composed of several cylinders arranged in parallel along a crankshaft (not shown).
The cylinder has a combustion chamber 5 formed by a cylinder 2, a cylinder head 3 and a piston 4. Reference numeral 6 denotes an intake passage, which communicates with the combustion chamber 5 via an intake valve 6a, and 7 denotes an exhaust passage, which communicates with the combustion chamber 5 via an exhaust valve 7a.

The intake passage 6 extends from the intake port 6b to the intake box 9 accommodating the intake pipe 8 and the air cleaner 9a for each cylinder formed in the cylinder head 3, and is gathered there to open to the atmosphere. 9b is an inlet for communicating the inside of the intake box 9 with the atmosphere, 10
Is a manually controlled throttle valve provided in the intake passage 6.

The intake pipe 8 is drawn out horizontally from one side of the cylinder head 3 in a substantially horizontal direction, is inverted upward to the upstream side of the throttle valve 10 and extends forward, into an intake box 9 provided in the vicinity of the cylinder head 3. It is open. 10a is a valve body of a butterfly-shaped throttle valve 10, 8b is a branch pipe for branching a high-speed passage 14 described later, and 8c is a branch pipe.
8b is an extension pipe that connects the intake box 9 with each other, and both form a part of the intake pipe 8 together with the intake box 9.

The intake boxes 9 are arranged side by side on the cylinder head 3 in the engine compartment of the automobile, but depending on the case, they may be arranged on the upper part or the front part of the cylinder head 3. As described above, the intake pipes 8 for each cylinder are assembled together. A high-speed intake box 12 to which the intake pipe 8 of each cylinder is connected is arranged ahead of the reversal portion of the intake pipe 8, and a high-speed passage 14 that linearly extends ahead of the reversal portion is branched. A secondary valve 16 is provided at the entrance of the high speed passage 14 and is closed in the low speed range.

Reference numeral 18 is a communication passage for communicating the space in the high-speed intake box 12 to a portion of each intake passage 6 which is on the downstream side of the throttle valve 10. By providing the communication passage 18, the respective intake passages 6 are communicated with each other through the communication passage 18 and the high-speed intake box 12. That is, the communication passage 18 and the high-speed intake box 12 form a so-called balance pipe to eliminate the instability of the intake negative pressure that occurs when the throttle valve 10 has a relatively low opening. Reference numeral 20 denotes an on-off valve provided in the communication passage 18, which is configured to be closed when the engine having no malfunction has a high output.

Next, the operation of this engine will be described. During low power operation in which the opening degree of the throttle valve 10 of the engine is low, the secondary valve 16 is also closed and the intake negative pressure generated in the combustion chamber 5 traces back through the intake passage 6. When it goes up and spreads to the intake box 9, the atmosphere is sucked into the intake box from the intake port 9b, passes through the air cleaner 9a, is distributed to the intake pipes 8 of each cylinder, and is introduced into the combustion chamber 5. The intake pipe 8 is set thick and long in advance, and at this time, the secondary valve 16
Since it is also closed, the intake inertia at low speed can be effectively used and a high low speed output can be obtained. Further, at this time, the on-off valve 20 is opened, so that the throttle valve 10 in each intake passage 6 is opened.
The parts on the downstream side of are communicated with each other via the communication passage 18 and the high-speed intake box 12. That is, the opening degree of the throttle valve 10 may vary among the intake passages 6 due to manufacturing error or the like. The intake air comes and goes through the balance pipe composed of 18 and the high-speed intake box 12, and the above-mentioned variation is offset. Therefore, the combustion is similarly performed in each cylinder during the low speed operation, and the operation is stabilized.

When the throttle valve 10 is greatly opened to increase the engine output, intake air is continuously introduced through the intake pipe 8. At this time, the secondary valve 16 is also opened, so that one of the reflected waves that accompanies the opening and closing of the intake valve 6a. The part returns to the intake box 9 via a long intake pipe 8. The rest is a high-speed passage 14 that extends linearly from the intake port 6b to the side.
Is obtained and propagates to the high-speed intake box 12. The length of the high-speed passage 14 is very short, but the volume of the high-speed intake box 12 also contributes to the resonance frequency, so it is set to obtain high output in the desired high-speed range including both (this calculation Since the law is a well-known design technology), a high output can be obtained even in a high output range, and as a result, a high engine output can be obtained over a wide operating speed range.

Further, although the high-speed intake box 12 is provided in the high-speed passage 14, it does not require an air cleaner, so that the structure is simple and downsizing is possible, and there is an advantage that maintenance is not required. is there.

〔The invention's effect〕

As described above, the intake system according to the present invention draws out the intake passage for each cylinder from one side of the multi-cylinder type cylinder head to the side, reverses it upward on the upstream side of the throttle valve, and extends it forward. Of the high-speed passage opened in the vicinity of the intake passage, and the high-speed passage opened and closed by a secondary valve that opens in the high-speed region downstream from the reversal part of the intake passage is branched, and the upstream ends of these high-speed passages are shared The intake chamber is opened to the downstream side of the throttle valve in each of the intake passages, and is communicated with each of the intake passages through an on-off valve that closes at high engine output. High pressure can be obtained by propagating the pressure wave from the high-speed passage to the intake chamber, and during low-speed operation, the balance pipe is composed of the communication passage and the intake chamber, and the negative pressure on the downstream side of the throttle valve for each intake passage is reduced. The variation of cancellation operated comes to stabilize.

Therefore, the same high output as that of the conventional engine having two kinds of intake passages for high speed and low speed can be obtained. Moreover,
The portion of the intake pipe connected to the engine body can be one for each cylinder, and the structure around the cylinder head and the intake pipe connection structure does not become complicated.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a cross-sectional view showing an outline of an engine, and FIG. 2 is a partially cutaway plan view thereof. 1 ... Engine body, 2 ... Cylinder, 3 ... Cylinder head, 4 ... Piston, 5 ... Combustion chamber, 6 ... Intake passage, 6a ... Intake valve, 6b ... Intake port, 7 ... Exhaust Passage, 7a ... Exhaust valve, 8 ... Intake pipe, 8b ... Branch pipe, 8c ...
… Extension pipe, 9 …… Intake box, 9a …… Air cleaner, 10 ……
Throttle valve, 10a …… Valve trunk, 12 …… High speed intake box, 14 …… High speed passage, 16 …… Secondary valve, 18 …… Communication passage, 20 …… Opening / closing valve.

Claims (3)

[Claims] 1. An intake passage provided in the vicinity of a cylinder head by drawing out an intake passage for each cylinder from one side of a multi-cylinder type cylinder head to a side, reversing upward to an upstream side of a throttle valve and extending forward. While opening into the box, the high-speed passages opened and closed by the secondary valve that opens in the high-speed region downstream from the reversal portion of the intake passage are branched, and the upstream ends of these high-speed passages are opened to the common intake chamber. An intake device for an engine, wherein the intake chamber is communicated with a portion of each of the intake passages on the downstream side of the throttle valve via an on-off valve that closes when the engine has a high output. 2. The intake system for an engine according to claim 1, wherein the intake box is arranged laterally above the cylinder head. 3. The intake system for an engine according to claim 1, wherein the intake box is arranged directly above the cylinder head.