JPS60153422A - Air intake equipment of engine - Google Patents

Abstract

PURPOSE:To improve the power of an engine in a high rotational range by the great intake air inertia effect by enabling variation in length of an intake passage in addition to enlargint the tuning range of said inertia effect by the chang- over of intake passage area. CONSTITUTION:When a number of revolutions of an engine reaches the primary specified number of revolutions N1, a change-over means 9 is driven to open a change-over valve 8. When the number of revolutions thereof is low and below the specified number N1, the primary suction passage 3a only is opened to supply intake air while when the number of revolutions is high and exceeds the specified number of revolutions N1, the secondary suction passage 3b as well as the primary suction passage 3a is opened to supply intake air. When the primary suction passage 3a only is opened and the number of revolutions is N1, the full throttle torque reaches a peak. When the number of revolutions exceeds number N2 at which the full throttle torque reaches a peak with both primary and secondary intake passages 3a and 3b opened, a driving means 20 is driven so as to shorten the length of the intake passage in accompany of increase in speed of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system, and in particular, to improving output by utilizing inertia supercharging by synchronizing the air column vibration of the intake system with the intake period. The present invention relates to an improvement of an engine intake system.

(Prior Art) Generally, the flow in the intake pipe is a so-called pulsating flow, and when the intake valve opens and the intake stroke begins, the air column in the intake pipe is accelerated due to the negative pressure generated in the cylinder and flows into the cylinder.

During this time, the cylinder internal pressure and volume change with the downward movement of the piston, and at the same time, the intake pipe internal pressure and speed also gradually change both in time and location. The pressure waves generated in the cylinder propagate through the intake pipe, are reflected at the surge tank, and return to the cylinder, and this phenomenon is repeated in the intake system. By synchronizing the frequency of the pressure change caused by the downward movement of the piston with the natural frequency of the intake system determined by the volume of the intake pipe and cylinder, an intake inertia effect can be obtained, improving volumetric efficiency and increasing output. It is well known that this can be realized.

The natural frequency of the intake system is determined by the length and cross-sectional area of the intake passage, and the average cylinder volume during the intake period.The natural frequency of the intake system is determined by the length and cross-sectional area of the intake passage, and the average cylinder volume during the intake period. In order to expand the upper region in the direction, various techniques have been proposed in which the length of the intake passage or the area of the intake passage is varied (for example, Japanese Patent Application Laid-Open No. 4E158214, Japanese Patent Application Laid-open No. 115819-1982, Japanese Patent Laid-Open No. 115819-1982). No. 119919).

However, in these prior art techniques, the effect of enlarging the upper t5 area in the exit direction by utilizing the intake inertia effect is small and insufficient, and it is desired to obtain greater tuning over a wider range.

(Objective of the Invention) In view of the above-mentioned circumstances, the present invention has been developed to improve the filling efficiency due to the above-mentioned intake inertia effect, because it is actually easier to achieve this in the high-speed range of the engine where the required length of the passage is relatively short. The object of the present invention is to provide an engine intake system that improves output by changing the passage area and length of the intake passage so that the inertia effect is maximized at each rotation speed in this high rotation range. It is something.

(Structure of the Invention) The intake system of the present invention includes an intake passage leading to one cylinder.
The intake passage is divided into an intake passage and a second intake passage, and these are switched according to the engine speed to change the area of the intake passage, and the length of both intake passages is made variable. This is characterized in that the length of the intake passage is changed in the high rotation range where intake air is being supplied.

(Effects of the Invention) According to the present invention, in addition to expanding the tuning range of the intake inertia effect by switching the intake passage area which can be realized with a simple structure, by making the intake passage length variable in the high rotation range, Compared to a system in which only the intake passage area or length is variable, the tuning range is expanded, and the intake direction can be effectively increased due to the large intake inertia effect in the high rotation range, and the intake flow rate can be improved in the low rotation range. It has various excellent advantages, such as the ability to improve performance through improvements.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional front view of essential parts of a multi-cylinder engine equipped with an intake system, and FIG. 2 is a sectional view taken along line II--II in FIG. 1.

An intake passage 3 that communicates with the combustion chamber 2 of each cylinder of the engine 1 is provided with a surge tank 5 downstream of the throttle valve 4, and is branched downstream of the surge tank 5 and connected to each cylinder independently.

The intake passage 3 in the vicinity of the combustion chamber 2 formed in the cylinder head 6 from the outer periphery of the surge tank 5 on the downstream side of the throttle valve 4 is formed by a partition wall 7 with a relatively small passage area. The first intake passage 3 is divided into a small first intake passage 3a and a second intake passage 3b having a relatively large passage area.
a opens to the first intake port 12a of the combustion chamber 2, and the second intake passage 3b opens to the second intake port 12b.

A switching means 9 having a switching valve 8 is interposed in the middle of the second intake passage 3b, and the switching valve 8 has its rotating shaft 8a linked to an actuator 10, and the switching valve 8 is controlled by a control unit 11 of the actuator 10. The second intake passage 3b is opened and closed by an operation based on a signal, and the intake passage area is changed between when intake air is supplied only through the first intake passage 3a and when intake air is supplied through both intake passages 3a and 3b. It is configured.

A part of the partition wall 7 downstream of the switching valve 8 is removed so that the first and second intake passages 3a and 3b on both sides communicate with each other, and a fuel injection nozzle 13 is disposed facing this communication part, so that a single A fuel injection nozzle 13 allows fuel to be supplied to both intake passages 3a and 3b.

The surge tank 5 is formed by a casing 14 and a cylindrical rotating member 15 rotatably installed inside the casing 14, and the surge tank 5 includes first and second intake passages 3a.
, 3b is constructed. This casing 14 forms an intake manifold fastened to the cylinder head 6 of the engine 1,
Independent intake passages 3 corresponding to each cylinder are connected to each other,
A first section partitioned by a partition wall 7 continuous from the cylinder head 6
Extended portions of the intake passage 3a and the second intake passage 3b are formed along the circumferential direction of the casing 14. The cylindrical rotating member 15 has an internal space that constitutes an expansion chamber downstream of the throttle valve 4, or in other words, a substantial surge tank serving as an intake air holding space, and has an opening 15a at the center of one end surface. is opened, and this opening 15a communicates with the upstream intake passage 3 provided with the throttle valve 4 to serve as an intake inlet. The intake passages 3a and 3b are partitioned, and each intake passage is made independent for each cylinder by being in contact with the inner wall surface of the intake passage 3 of the casing 14 for adjacent cylinders. The circumferential surface of the rotating member 15 has a first
A rectangular communication port 15b on the outlet side communicating with the second intake passages 3a, 3b is opened, and the inner space and the first and second intake passages 3a,
3b is changed, so that the substantial length of each intake passage 3a, 3b as an independent intake passage from the surge tank 5 to each cylinder becomes variable.

A shaft portion 15c protruding outward from the casing 14 is connected to the narrow end surface of the rotating member 15, and is rotatably supported by the casing 14 around the shaft portion 15c and the opening 15a. A gear 18 fixed to the output shaft of a motor 17 is meshed with an input horn gear 16 fixed to the end, thereby forming a driving means 20 that changes the path length by rotation of the rotating member 15. The above motor 17
are also driven and controlled by control signals from the control units 1 to 11.

The above control units I to 11 have a rotation speed sensor 2.
The control units 1 to 11 are provided with a switching means 9 for changing the intake passage area and a passage length variable means for changing the length of the intake passage in response to fluctuations in the engine rotation speed. The driving means 20 of 19 is drive-controlled, and the intake passage area and the intake passage length are set to values at which the air column frequency of the intake passage 3 and the cycle of the intake period based on the engine rotation speed are synchronized and the intake inertia effect is maximized. It is to be adjusted to.

In FIG. 1, 22 is an intake valve, 23 is a cylinder block, and 24 is a piston.

FIG. 3 shows the control of the area of the intake passage by switching the intake passages 3a and 3b according to the engine speed by the controllers 1 to 11, and the control of the length of the intake passage by rotating the rotating member 15.

When the engine speed reaches the first set speed N1, the switching means 9 is driven to open the switching valve 8, and this set speed N1 is driven.
In the low rotation speed range of 1 or less, intake air is supplied by only the first intake passage 3a with a small intake passage area, while in the high rotation range exceeding the set rotation speed N1, the second intake passage is supplied in addition to the first intake passage 3a. 3b, the passage area is switched and controlled so that intake air is supplied with a large intake passage area.

On the other hand, intake passage length control basically increases the passage length when the engine speed is low, and shortens the passage length when the engine speed rises and becomes high. Then, in the high rotation range after the switching valve 8 opens, the driving means 20 is driven at a second set rotation speed N2 or more, and the passage length is shortened as the engine rotation speed increases. It is something.

According to the above control, as shown in FIG.
From the relationship with the curve (■) when air is supplied by both the intake passages 3a and 3b, the first set rotation speed N at which the two are switched is determined.
1, that is, setting the operating timing of the switching means 9,
By shortening the second set rotation speed N2 set at the time when the curve ■ exceeds the peak and the length of the intake passage, an intake inertia effect is obtained, and as shown by the chain line ■, a large decrease in output is suppressed. The purpose is to improve output.

Therefore, in the above embodiment, in addition to the passage area switching means, the passage length is varied in the high rotation range, so that the fluctuation width of the natural frequency of the intake system can be reduced in the high rotation range where the intake inertia effect is required. It can be made both large and fine, and the intake inertia effect can be obtained over a wide range to improve output.

In addition, combustion performance can be improved in the low rotation range by reducing the intake passage area and improving the intake flow velocity, and in the high rotation range, the intake passage area is increased to increase the intake air from multiple mouths. can be supplied.

Roughly speaking, in the above embodiment, the passage length variable means 19 for changing the length of the intake passage is constituted by an intake passage extension formed around the surge tank 5 and a rotating member that rotates along this extension. As a result, the entire structure can be made compact, the structure can be simplified, and reliable operation can be ensured. Furthermore, in a high rotation range, the length of the intake passage during synchronization is short, and the length of the intake passage to be changed in response to fluctuations in the engine rotation speed can also be shortened, so that further compactness can be achieved.

In the above embodiment, the passage area of the first intake passage 3a is smaller than the passage area of the second intake passage 3b.
The passage area of the second intake passage 3b may be larger than the passage area of the second intake passage 3b.

Further, since the above-mentioned inertial supercharging is necessary at times of high load, the passage length control as in the embodiment may be performed only at times of high load.

Furthermore, in the above embodiment, the first and second intake passages 3a
, 3b are removed to communicate with each other, but this communication may be eliminated to form both intake passages 3a, 3b completely independently. At that time, the natural frequency of the intake system changes slightly.

Alternatively, a single intake boat 1 may be opened in the combustion chamber 2, and the intake passage on the upstream side of this intake boat may be divided into a first intake passage and a second intake passage.

On the other hand, the switching means 9iB and the driving means 20 for changing the intake passage area and the intake passage length are operated by the controller 1 to the roll unit 11 which detect the engine speed as in the above embodiment, and also by the exhaust pressure It is possible to appropriately adopt means that operates based on a signal having a correlation with the engine rotational speed, such as drive control using an actuator that operates in response to the engine speed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of essential parts of an engine having an intake system according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the I[-IF line in FIG. 1, and FIG. 3 shows an example of control characteristics. Explanatory diagram: FIG. 4 is a characteristic diagram showing the relationship between engine speed and full-throttle torque based on the control shown in FIG. 3. 1...Engine 3...Intake passage 3a
......First intake passage 3b...Second intake passage 5...Surge tank 8...Switching valve 9...Switching means 11. ...Control unit 14...
・Casing 15...Rotating member 19...
... Passage length variable means 20 ... Drive means - Fig. 2 Fig. 3 Number of λ during engine rotation Fig. 4 Engine rotation (momme 273-

Claims (1)

[Claims] (1) The intake passage leading to the cylinder is formed at least in part by a first intake passage and a second intake passage, and includes a switching means for opening and closing the second intake passage to switch the passage area for supplying intake air. In the engine intake system, the switching means is operated so that the area of the intake passage increases in response to an increase in engine speed, wherein the intake passage lengths of the first and second intake passages are variable. A passage length variable means is provided so that the length of the intake passage is shortened in response to an increase in engine rotation speed in a high rotation range where the switching means is activated and intake air is supplied by the first and twenty-first intake passages. An intake system for an engine, characterized in that the drive means for the passage length variable means is controlled in operation.