JPS58148227A - Intake device of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To effectively decreases a pumping loss of each cylinder, by using a timing valve, controlled to close before an intake port is closed at an intake stroke, to avoid the cylinders from interfering with each other. CONSTITUTION:Each intake passage 4a, 4d of the first cylinder 1a and the fourth cylinder 1d and each intake passage 4b, 4c of the second cylinder 1b and the third cylinder 1c are collected respectively to form common intake passages 5a, 5b. Thiming valves 6a, 6b are overlapped for intake valve open timing of each cylinder 1a-1d. Only in an overlapped period, a mixture of required amount is sucked by small negative pressure (approximate to the atmospheric pressure). In consequence, as compared with a case when intake air is throttled by using a throttle valve, a suction loss by intake negative pressure is decreased to reduce a pumping loss. Close timing of the timing valve for close timing of an intake valve is arranged earlier at a low load of an engine than at its high load.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a multi-cylinder engine.

In general, an Otto cycle engine has a problem in that when the thermal energy generated in the cylinders is extracted as output, a part of it is lost through so-called pumping loss, which reduces thermal efficiency and impedes improvement in fuel efficiency. This pumping loss is a suction loss due to the negative work that the intake negative pressure acts on the piston during the intake stroke, and the pumping loss due to the suction loss becomes large especially at low load when the intake negative pressure increases.

To address this problem, various means have been developed to reduce the pumping loss, one of which is the Japanese Patent Application Laid-Open No.
As seen in Japanese Patent No. 9<5313, an intake device is known in which a timing valve is provided in an intake passage. That is,
This intake system eliminates the throttle valve or increases the opening of the throttle valve in advance.Instead, a timing valve (rotary valve) is installed on the intake boat upstream of the intake valve, and the intake boat is closed by the intake valve during the intake stroke. The timing valve is closed before the intake valve is opened, and the air-fuel mixture is sucked in while both the timing valve and the intake valve are open. According to this, the intake negative pressure during the mixture suction period is reduced, and the loss due to the negative pressure after the timing valve is closed is offset by the action of pulling the piston up in the compression stroke, thereby reducing the pumping loss.

By the way, conventionally, when applying a pumping loss reduction means using such a timing valve to a multi-cylinder engine,
Since each cylinder was provided with the above-mentioned timing valve individually, it was necessary to provide the same number of timing valves as the number of cylinders and an interlocking mechanism that rotates each timing valve in synchronization with the engine, resulting in a structurally It has the drawbacks of complication and high cost.

In view of these circumstances, the present invention, when applying a pumping loss reduction means using a timing valve to a multi-cylinder engine, allows the timing valve to be shared by a plurality of cylinders, so that each cylinder can be effectively reduced by using fewer timing valves than the number of cylinders. To provide an intake system for a multi-cylinder engine that can reduce cylinder pumping loss and greatly simplify the structure while maintaining the same functionality as when compared to a case where each cylinder is provided with an individual timing valve. That is.

That is, the intake system of the present invention is based on the premise that the timing valve is closed before the intake boat is closed during the intake stroke, and the intake passages of the cylinders in which the opening timings of the intake boats do not overlap each other in a multi-cylinder engine are grouped together. The common intake passage formed in this manner is provided with a timing valve that opens the common intake passage at a predetermined time corresponding to the opening timing of the intake boat of each cylinder.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the device of the present invention is applied to a four-stroke, four-cylinder engine. In the figure, 1a to 1d are cylinders, each of which has an intake boat 2... and an exhaust boat 3-.
* are connected to individual intake passages 4a to 4d, respectively. Among these intake passages 4a to 4d, those whose opening timings of the intake boats do not overlap with each other are grouped together to form common intake passages 5a and 5b. That is, in this embodiment, if the cylinders 1a to 1d are called the first to fourth cylinders in order from the left side of the first cylinder, the first cylinder 1a and the fourth cylinder The intake passages 4 a e 4 d of the cylinder 1 d are assembled, and the intake passages 4 b and 4 c of the second cylinder 1 b and the sixth cylinder 1 C are assembled to form two common intake passages 5 a and 5 b. ing. Each common intake passage 5a #5b is provided with a rotary timing valve 6a, 6b, respectively. These timing valves 6 a m 6 b are connected to timing pulleys 8 and 9 and a timing belt 1 so that they rotate synchronously with respect to the engine crankshaft 7 at a predetermined rotation ratio, which will be described later.
0, and the valve opening/closing phase is adjusted by an appropriate opening/closing timing adjusting means (not shown) in response to accelerator operation or the like. Further, both the common intake passages 5a and 5b communicate with the pumping passage gathering portion 11 upstream from the timing valve arrangement location, and this intake passage gathering portion 11F
An air cleaner 12 and a carburetor 13 are provided.

The specific structure of the cylinders and timing valves will be explained with reference to FIG. 2. Each of the cylinders 1a to 1d is equipped with a piston 15 connected to the crankshaft 7, and there is a gap between the top surface of the piston 15 and the inner surface of the cylinder. A working chamber 16 is formed therebetween. An intake valve 17 and an exhaust valve 18 are provided in the intake boat 2 and the exhaust port 6 that open into the working chamber 16. The timing valves 6a and 6b are each formed into a cylindrical shape having a pulp hole 19 penetrating in the diametrical direction, and as they rotate, the pulp hole 19 is in a state in which it communicates with the common intake passages 5a and 5b and a state in which it is not in communication. By gradually changing, the common intake passages 5a and 5b are opened and closed.

The common intake passages 5a, 5b and the timing valves 6a, 6b are constructed according to the following conditions.

That is, first of all, as a basic condition for reducing the pumping loss using a timing valve, as shown in FIG. It opens before the intake valve of the corresponding cylinder is opened, and closes before the intake valve closes during the intake stroke, and within this condition, the opening and closing timing of the timing valve is adjusted according to accelerator operation, etc. In other words, the timing at which the timing valve closes relative to the timing at which the intake valve closes is set to be earlier when the engine is under light load than when the engine is under high load.

In addition, as a condition for forming a common intake passage where the timing valve is placed, if the intake passages of cylinders whose intake valve opening timings (intake boat opening timings) overlap are grouped together, the intake actions of these cylinders will interfere with each other. This makes intake control difficult, so the intake passages of cylinders whose intake valve opening times do not overlap are grouped together. That is, in the engine shown in FIG. 1, ignition occurs in the first cylinder IW1a, the third cylinder 1C1, the fourth cylinder 16. The strokes of each cylinder are shifted by 180 degrees in crank angle according to the ignition order as shown in Fig. 4, but the intake valve starts opening just before the intake stroke, and at the end of the intake stroke. However, because the valves do not close completely and then close immediately after that, the opening period of the intake valves is partially delayed in cylinders whose strokes differ by 180 degrees. Therefore, each intake passage 4a, 4 of the first cylinder 1a and the fourth cylinder 1d
d, and each intake passage 4 of the second cylinder 1b and the sixth cylinder 1C.
b.

4C are gathered together to form common intake passages 5a and 5b.

Further, the timing valves 6a and 6b provided in the respective common intake passages 5a and 5b are configured to open the common intake passage for each of the cylinders in which the intake passages are assembled at the timing shown in FIG. do. In order to satisfy this condition, the timing valves may be opened every time the crankshaft rotates by 360 degrees, corresponding to two cylinders whose strokes differ by 660 degrees in terms of crank angle. Each of the timing valves 6a
, 6b open every time the timing valves 6a and 6b rotate by 180 degrees, so the speed is adjusted to 180 degrees when the crankshaft rotates.
1 It is sufficient to set the rotation speed to 360, that is, /2.

In this device, the timing valve 6a.

6b is the sixth valve opening timing for each cylinder 1a to 1d.
The common intake passages 5a, 5b are opened at the timing shown in the figure.
By opening the cylinders 1a to 1d, the required amount of air-fuel mixture is sucked in at a small negative pressure (pressure close to atmospheric pressure) during the wrap period of the timing valve and intake valve shown by diagonal lines in FIG. .

Therefore, compared to the case where the intake air is throttled using a throttle valve, the suction loss due to the intake negative pressure is reduced, and the pumping loss is reduced. In particular, both the timing valves 6a and 6b are
Since the intake boat opening timing is shared by multiple cylinders that do not overlap, the number of timing valves is reduced and the structure is simplified compared to a case where a timing valve is installed individually for each cylinder. Moreover, there is no problem with the intake action and the pumping loss reduction action.

FIG. 5, FIG. 7, and FIG. 9 show respective embodiments in which the device of the present invention is applied to a four-stroke two-cylinder, three-cylinder, and six-cylinder engine. In these cases as well, the above 4
According to predetermined conditions similar to those of a four-cylinder cycle engine, the intake passages of a plurality of cylinders are assembled to form a common intake passage, and the rotational speed of the timing valve with respect to the crankshaft is determined. These configurations are as follows when a timing valve having the same shape as the timing valve shown in FIG. 2 is used.

That is, in the case of the 4-cycle two-cylinder engine shown in FIG. 5, the strokes of the leg cylinders 21a and 21b are shifted by 360 degrees in terms of crank angle as shown in FIG. 6, and the opening timings of the intake boats of the leg cylinders 21a and 21b do not overlap. . Therefore, the intake passages 24a and 24b of the leg cylinders 21a and 21b may be assembled to form a common intake passage 25, and the common intake passage 25 may be provided with a timing valve 26. Further, the rotational speed of the timing valve 26 is set to 1/2 of the crankshaft rotational speed as in the case of a 4-stroke, 4-cylinder engine.

In the case of the 4-cycle 3-cylinder engine shown in FIG. 7, the strokes of each cylinder 31a-31c are as shown in FIG.
1a1 3rd cylinder 31c, 240° in the order of 2nd cylinder 31b
The opening timings of the intake boats for each cylinder 31a to 31c do not overlap. Therefore, these cylinders 31a~
The intake passages 34a to 34c of 31c are assembled to form a common intake passage 35, and a timing valve 36 is provided. The timing valve 66 is set to 6/4.

In the case of the 4-cycle 6-cylinder engine shown in FIG.
The ignition order and stroke deviations of the sixth cylinders 41a to 41f are as shown in FIG. Therefore, when the intake boat is opened, the cylinders 1 to 6, 41
Each of the intake passages 44a to 44c of a to 41c and each of the intake passages 44d to 44 of the fourth to sixth cylinders 41d to 41f
f are gathered together to form two common intake passages 45a, 4
A timing valve 46a, 46b is provided in each common intake passage 45a, 45b. The rotational speed of the timing valves 46a, 46b is set to 374 degrees of the rotational speed of the crankshaft, as in the case of a 4-stroke, 6-cylinder engine.

Note that the shape of the timing valve used in the device of the present invention is not limited to the one shown in the figure, but has a through hole in the shape of a cross.
It is also possible to adopt a shape that opens the valve each time it rotates.
If the number of openings of the timing valve per revolution changes due to such a design change, the rotational speed ratio between the timing valve and the crankshaft may be changed accordingly. Furthermore, the device of the present invention can be applied to various multi-cylinder engines such as two-stroke multi-cylinder engines, in addition to the engines shown in the above embodiments.

As described above, the device of the present invention reduces pumping loss by using a timing valve that closes before the intake port is closed during the intake stroke, and in particular, the timing valve is applied to multiple cylinders where the opening timing of the intake boat does not overlap. Since the timing valves are shared, it is possible to effectively reduce the pumping loss of each cylinder by avoiding interference between the intake actions of each cylinder. In comparison, the structure can be significantly simplified.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the device of the present invention, FIG. 2 is a sectional view of the main part, and FIG. 3 is an explanatory diagram showing the relationship between the opening timings of the timing valve and the intake and exhaust valves. FIG. 4 is an explanatory diagram showing the stroke correspondence of each cylinder of the engine shown in FIG. 1, FIG. 5 is a schematic diagram showing the second embodiment, and FIG. 6 is a diagram showing the stroke correspondence of each cylinder in the same example. FIG. 7 is a schematic diagram showing the third embodiment; FIG. 8 is an explanatory diagram showing the stroke correspondence of multiple cylinders in the same example; FIG. 9 is a schematic diagram showing the fourth embodiment; The figure is an explanatory diagram showing the stroke correspondence of each cylinder in the same example.
41 a ~ 41 f-... Cylinder, 4a ~ 4d, 24
a. 24b, 34a to 34c, 44a to 44f"
-Intake passage, 5a, 5b, 25, 35
, 45 a 45 b --- common intake passage, 6a, 6
b, 26, 36, 46a, 46b...timing valve. Patent Applicant: Toyo Kogyo Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 77-71'llL - Figure 5 Figure 6 Figure 7 Figure 8 IA or Figure 9 Figure 10, etc. ′! nourishment

Claims (1)

[Claims] 1. An intake boat that opens into the working chamber of the engine, and a timing valve that is provided in an intake passage communicating with the intake boat and opens and closes the intake passage in synchronization with engine rotation,
In a multi-cylinder engine in which the timing valve is closed before the intake boat is closed during the intake stroke to reduce engine pumping loss, the above-mentioned intake passages of the cylinders whose opening timings of the intake boats do not overlap with each other are collected and shared. An intake system for a multi-cylinder engine, characterized in that an intake passage is formed, and the timing valve for opening the common intake passage when the intake boat of each cylinder is opened is provided in the common intake passage.