JPH0380971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake system for a multi-cylinder engine having a timing valve in an intake passage.

[Conventional technology]

2. Description of the Related Art Conventionally, an intake system is known in which a timing valve is provided in an intake passage of an engine, and the timing valve adjusts intake air supply to each cylinder of the engine according to the operating state. For example, Tokukai Akira
Japanese Patent No. 55-96313 discloses an intake device in which a timing valve is provided in an intake passage in order to reduce pumping loss due to negative work caused by intake negative pressure acting on a piston during the intake stroke. 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 in the intake passage upstream of the intake valve, and the intake port 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 air-fuel 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 up the piston during the compression stroke, thereby reducing pumping loss.

[Problem to be solved by the invention]

By the way, in conventional intake systems equipped with such timing valves, each cylinder is provided with the above-mentioned timing valves individually, so it is necessary to provide the same number of timing valves as the number of cylinders and to synchronize these timing valves with the engine. An interlocking mechanism must be provided to rotate the device, which has the disadvantage of complicating the structure and increasing cost.

In view of these circumstances, the present invention, when adjusting the intake air supply to each cylinder using a timing valve, allows the timing valve to be shared by a plurality of cylinders, and effectively controls each cylinder by using a timing valve smaller than the number of cylinders. The present invention provides an intake system for a multi-cylinder engine that can greatly simplify the structure while maintaining equivalent functionality compared to a case where a timing valve is provided individually for each cylinder. be.

[Means to solve the problem]

In order to achieve the above objects, the present invention includes an intake port that opens into a working chamber of an engine, and a timing valve that is provided in an intake passage communicating with the intake port and opens and closes the intake passage in synchronization with engine rotation. In this multi-cylinder engine, the intake passages of the cylinders whose opening timings of intake ports do not overlap with each other are grouped together to form a common intake passage, and the timing valve is disposed in the common intake passage.

[Effect]

According to the above configuration, the timing valve is shared by a plurality of cylinders, and it is possible to adjust the intake air supply to each cylinder while avoiding interference between the intake operations of each cylinder.

〔Example〕

Embodiments of the present invention will be described based on 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 port 2 and an exhaust port 3 opened in its working chamber.
Each of the above-mentioned intake ports 2 communicates with individual intake passages 4a to 4d. Among these intake passages 4a to 4d, those whose opening timings of the intake ports do not overlap with each other are grouped together to form common intake passages 5a and 5d. 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 FIG. 1, the first cylinder 1a and the fourth cylinder The intake passages 4a and 4d for the cylinder 1d are gathered together, and the intake passages 4b for the second cylinder 1b and the third cylinder 1c,
4c to form two common intake passages 5a and 5b.
is formed. These common intake passages 5a, 5b
are equipped with rotary timing valves 6a and 6, respectively.
b is provided. These timing valves 6a,
6b is interlocked and connected to the crankshaft 7 of the engine via timing pulleys 8, 9 and a timing belt 10 so as to rotate synchronously at a predetermined rotation ratio, which will be described later. (not shown), the valve opening/closing phase is adjusted in response to accelerator operation or the like. Also,
Both the common intake passages 5a and 5b communicate with the intake passage gathering portion 11 upstream from the timing valve arrangement location,
An air cleaner 12 and a carburetor 13 are provided in this intake passage gathering portion 11 .

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 the top surface of the piston 15 and the inner surface of the cylinder A working chamber 16 is formed between the two. An intake valve 17 and an exhaust valve 18 are provided in the intake port 2 and exhaust port 3 that open into the working chamber 16. Further, each of the timing valves 6a and 6b is formed in a cylindrical shape having a valve hole 19 penetrating in the diametrical direction, and as the timing valves 6a and 6b rotate, the valve hole 19
9 gradually changes between a state in which it communicates with the common intake passages 5a and 5b and a state in which it does not communicate with the common intake passages 5a and 5b, thereby opening and closing the common intake passages 5a and 5b.

The common intake passages 5a, 5b and timing valves 6a, 6b are constructed in accordance with the following conditions.

In this embodiment, a timing valve is used to reduce pumping loss, and in this case, the timing valve is used as shown in Fig. 3, which shows the relationship between the timing valve and the opening timings of the intake valve and exhaust valve. The timing valve is opened before the intake valve of the corresponding cylinder is opened, and closed before the intake valve is closed during the intake stroke, and the opening and closing timing of the timing valve is adjusted according to accelerator operation, etc. within the range of these conditions. do. That is, 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 a light load than when the engine is under a high load.

In addition, as a condition for forming a common intake passage in which the timing valve is arranged, if the intake passages of cylinders whose intake valve opening timings (intake port opening timings) overlap are grouped together, the intake action of these cylinders will be affected. interfere with each other, making intake control difficult.
To gather together intake passages of cylinders whose opening timings of intake valves do not overlap. In other words, in the engine shown in FIG. 1, ignition occurs in the first cylinder 1a and the third cylinder 1a.
c, the fourth cylinder 1d, and the second cylinder 1b, and 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 is placed just before the intake stroke. The intake valves begin to open from then on, and do not close completely even at the end of the intake stroke, but close immediately thereafter, so the opening timing of the intake valves will partially overlap in cylinders whose strokes are 180 degrees apart. Therefore, the first cylinder 1a
and each intake passage 4a, 4d of the fourth cylinder 1d, and each intake passage 4b of the second cylinder 1b and third cylinder 1c,
4c are gathered together to form a common intake passage 5a, 5.
b is formed.

Furthermore, 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 should be opened every time the crankshaft rotates 360 degrees, corresponding to two cylinders whose strokes differ by 360 degrees in crank angle. The timing valves 6a and 6b are
Since the valve opens every time the timing valve rotates 180 degrees, the rotational speed of each timing valve 6a, 6b may be set to 180/360, or 1/2, of the rotational speed of the crankshaft.

In this device, the timing valve 6a,
6b opens the common intake passages 5a and 5b at the timing shown in FIG. 3 relative to the intake valve opening timing of each cylinder 1a to 1d.
In each case, the required amount of air-fuel mixture is sucked in at a small negative pressure (a pressure close to atmospheric pressure) only during the lap period between the timing valve and the intake valve, which are indicated by diagonal lines in FIG. Therefore, compared to the case where intake air is throttled using a throttle valve, suction loss due to intake negative pressure is reduced, and pumping loss is reduced.

In particular, since both of the timing valves 6a and 6b are shared by a plurality of cylinders whose intake port opening timings do not overlap, the timing valve The structure is simplified by reducing the number of , and there is no problem with the intake action and 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, the intake passages of a plurality of cylinders are grouped together to form a common intake passage, and the rotational speed of the timing valve relative to the crankshaft is determined according to predetermined conditions similar to those of the 4-cycle 4-cylinder engine. be done. These configurations are as follows when a timing valve having the same shape as the timing valve shown in FIG. 2 is used.

In other words, in the case of the four-stroke two-cylinder engine shown in FIG. 5, the strokes of both cylinders 21a and 21b are the sixth stroke.
As shown in the figure, there is a 360° shift in crank angle, and both cylinders 2
The opening timings of the intake ports 1a and 21b do not overlap. Therefore, the intake passages 24a and 24b of these two cylinders 21a and 21b are combined into a common intake passage 25.
, and a timing valve 26 may be provided in the common intake passage 25. Also, the rotational speed of the timing valve 26 is 1/2 of the crankshaft rotational speed, as in the case of a 4-stroke, 4-cylinder engine.
is set to

In the case of the 4-stroke, 3-cylinder engine shown in FIG. 7, the strokes of each cylinder 31a to 31c are shifted by 240 degrees in the order of the first cylinder 31a, the third cylinder 31c, and the second cylinder 31b, as shown in FIG. Again each cylinder 31
The intake port opening timings of a to 31c do not wrap. Therefore, the intake passages 34a to 34c of these cylinders 31a to 31c are combined to form a common intake passage 35.
A timing valve 36 is provided. The rotational speed of the timing valve 36 is equal to the rotational speed of the crankshaft.
It is set to 180/240 or 3/4.

In the case of the 4-stroke, 6-cylinder engine shown in FIG. 9, the ignition order and stroke deviations of the first to sixth cylinders 41a to 41f are as shown in FIG. 10. Therefore, the intake passages 44a to 44c of the first to third cylinders 41a to 41c and the fourth to sixth cylinders 4
The intake passages 44d to 44f of 1d to 41f are assembled into two common intake passages 45a and 45.
b is formed, and these common intake passages 45a, 45
Timing valves 46a and 46b are provided at b.
The rotational speed of the timing valves 46a, 46b is set to 3/4 of the rotational speed of the crankshaft, as in the case of a 4-stroke, 3-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 illustration, but may also have a cross-shaped through hole and open every time it rotates 90 degrees. If the number of openings of the timing valve per rotation changes due to 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.

[Effects of the Invention] As described above, the device of the present invention adjusts the intake air supply to each cylinder using the timing valve provided in the intake passage. Since the timing valves are shared, it is possible to effectively adjust the intake air supply to 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 each cylinder 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. 1a-1d, 21a, 21b, 31a-31
c, 41a to 41f...Cylinder, 4a to 4d, 24
a, 24b, 34a-34c, 44a-44f...
...Intake passage, 5a, 5b, 25, 35, 45a,
45b...Common intake passage, 6a, 6b, 26, 3
6, 46a, 46b...timing valve.

Claims (1)

[Claims] 1 An intake port that opens into the working chamber of the engine,
In a multi-cylinder engine equipped with a timing valve that is provided in an intake passage communicating with the intake port and opens and closes the intake passage in synchronization with engine rotation, the intake passages of cylinders whose opening timings of the intake ports do not overlap each other are grouped together. An intake system for a multi-cylinder engine, characterized in that a common intake passage is formed, and the timing valve is disposed in the common intake passage.