JP2003201847A - Intake device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake device for an engine which enhance the engine torque by heightening the intake filling efficiency in the intermediate rotation range, compared with any conventional arrangement. <P>SOLUTION: The intake device of the engine is furnished with a first intake passage to put a surge tank in communication with an inlet hole in the cylinder head and a second inlet passage branching at the middle part of the first passage and putting the part to the surge tank in communication through a passage length shorter than the first passage, wherein a first opening/closing valve is installed in the tank side communication part of the second passage while a second opening/closing valve is installed in the first passage side communication part, and a changeover control is conducted at four stages; at least one of the first and second valves is closed in the low rotation range in association with the rise of the engine speed, and only the second valve is opened in the intermediate, first rotation range while only the first valve is opened in the intermediate, second rotation range, and both the first and second valves are opened in the high rotation range. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an engine, and more particularly to an intake system for an engine in which an intake air charging efficiency in an intermediate rotation range is further increased as compared with a conventional system. The present invention relates to an intake device for an engine to be improved. 2. Description of the Related Art In an engine, a first intake passage communicating between a surge tank and a cylinder head is provided, and the engine branches off from an intermediate portion of the first intake passage to communicate with the surge tank. A second intake passage communicating with a passage length shorter than the first intake passage is provided, and an on-off valve provided in the second intake passage controls the flow of the intake air to improve the output by utilizing the resonance supercharging effect. There is a device. As an intake device for the engine, there is one disclosed in Japanese Patent Application Laid-Open No. 1-117919. An intake device for an engine disclosed in this publication is an engine in which a resonator having a predetermined volume communicates with an intake passage on the downstream side of a throttle valve, and is provided in a communication passage between the intake passage on the downstream side of the throttle valve and the resonator. An on-off valve for opening and closing the valve, and on-off valve control means for controlling the open state of the on-off valve. As a condition, valve closing control is performed, and it is possible to reliably prevent the occurrence of an over-rich condition of the engine air-fuel ratio. Let me. [0004] Also, there is one disclosed in JP-A-8-42349. The intake device of the multi-cylinder engine disclosed in this publication communicates with each of the independent intake passages via a branch pipe that branches from the middle of the independent intake passage separately from the first volume chamber to which the independent intake passage corresponding to each cylinder is connected. And a control valve that opens and closes in accordance with an operation state in each branch passage, and sets a cross-sectional area of the second volume chamber larger than a cross-sectional area of each independent intake passage. The output has been improved over a wide operating range without drastically changing the intake system that exerts. [0005] Furthermore, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 9-137729. An intake device for an internal combustion engine disclosed in this publication includes an air cleaner volume that accommodates an air cleaner that filters an intake air flow to the internal combustion engine, a throttle valve provided downstream of the air cleaner volume, and a throttle valve provided downstream of the throttle valve. A chamber portion provided so as to be able to communicate with the surge tank portion through a first opening to the air cleaner volume portion, and a chamber portion provided so as to be able to communicate with the surge tank portion through a second opening. A first opening / closing means for opening / closing the first opening, a second opening / closing means for opening / closing the second opening, and when the rotation speed of the internal combustion engine satisfies a predetermined condition, only one of the first and second openings is opened. Control means for controlling the driving of the first and second opening / closing means as described above, and a plurality of functions are achieved by sharing parts. [0006] Furthermore, there is a technology disclosed in Japanese Patent Application Laid-Open No. 9-287559. In the intake device for an engine disclosed in this publication, second and third passages having a larger cross-sectional area than the first passage and a shorter length are arranged adjacent to and parallel to the first passage. The first passage is communicated, the second passage is communicated in the middle rotation region, and the second,
By communicating with the third passage and performing intake by inertial supercharging by synchronizing the timing of the air column vibration of the intake system with the intake period, the output of the full-open torque is improved over the entire rotation range of the engine. [0007] In a conventional engine intake device, as shown in FIG. 7, a first intake passage communicating between a surge tank 106 and a cylinder head (not shown). (Also referred to as a “main branch”) 108 and a second intake that branches from an intermediate portion of the first intake passage 108 and communicates with the surge tank 106 with a shorter passage length than the first intake passage 108. An opening / closing valve (also referred to as a “shutter valve”) 1 for providing a passage (also referred to as a “sub-branch”) 110 and opening and closing the second intake passage 110 in accordance with the engine speed.
13 is connected, for example, to the surge tank 106 side communication portion 110-1.
The first and second intake passages 108 and 110 of the intake manifold 104 are switched by an on-off valve 113 to control the intake air flow and utilize two kinds of resonance effects. [0008] The conventional intake system for an engine as described above is a known fact and is in practical use. In the region where the engine speed is low,
As shown in FIG. 8, by closing the on-off valve 113 and using the first intake passage 108 as the main branch, the passage length becomes long and narrow, and the resonance supercharging of low frequency and the inertia effect are utilized. . In a high engine speed region, as shown in FIG. 9, by opening the on-off valve 113 and using the second intake passage 110 as a sub-branch, a passage shorter than the first intake passage 108 is provided. It is long and thick, and utilizes reduction of ventilation resistance and high-frequency resonance supercharging. As a result, good torque characteristics are obtained from a low engine speed range to a high engine speed range. However, in the conventional system of the intake system of the engine, since only one opening / closing valve is provided, the capacity of the system cannot be sufficiently brought out, and improvement has been desired. . As will be additionally described, the torque characteristic due to the opening / closing operation of the on-off valve, as shown in FIG.
In addition to the torque characteristics of the line segment C (symbol “O”),
When the on-off valve is opened, the torque characteristic of the line segment E (symbol "+") is obtained, and the on-off valve is operated from the closed state to the open state at the engine speed N4. As a result, although the torque characteristics at the engine speed N4 or higher (see T4 in FIG. 4) can be improved, the engine speed is lower than the engine speed N4 and the shape of the conventional intake device is not largely changed. There has been a demand for a method that can further improve the torque characteristics. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a first intake passage communicating between a surge tank and an intake hole of a cylinder head;
A second intake passage that branches from an intermediate portion of the intake passage and communicates with the surge tank with a shorter passage length than the first intake passage is provided, and the second intake passage is opened and closed according to the engine speed. In an intake device for an engine provided with an on-off valve, a first on-off valve is provided on a surge tank-side communication portion of the second intake passage, and a second on-off valve is provided on a first intake passage-side communication portion.
An on-off valve is provided, and at least one of the first on-off valve and the second on-off valve is closed in a low rotation range with an increase in engine speed, and only the second on-off valve is opened in an intermediate first rotation range. In the intermediate second rotation range, only the first opening / closing valve is opened, and in a high rotation range, switching control is performed in four stages in which both the first opening / closing valve and the second opening / closing valve are opened. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As the engine speed increases, the first and second on-off valves are switched and controlled in four stages. In particular, the second intake passage is made to act as a surge tank resonator in the intermediate second rotation range. In comparison, the engine charging is improved by further increasing the intake charging efficiency in the intermediate rotation range. Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 show an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes an intake device for an engine (not shown). The intake device 2 has an intake manifold 4, and a surge tank 6 is provided in the intake manifold 4. A first intake passage 8 as a plurality of main branches communicating between the surge tank 6 and a plurality of intake holes (not shown) of a cylinder head (not shown).
And a second intake passage 10 that is a sub-branch that branches off from an intermediate portion of the first intake passage 8 and communicates with the surge tank 6 with a shorter passage length than the first intake passage 8. At this time, the first opening / closing valve 12 is provided in the communication portion 10-1 of the second intake passage 10 on the surge tank 6 side, and the second opening / closing valve 14 is provided in the communication portion 10-2 of the first intake passage 8 side. And at least one of the first on-off valve 12 and the second on-off valve 14 is closed in a low rotation range with an increase in engine speed, and only the second on-off valve 14 is opened in an intermediate first rotation range. In the intermediate second rotation range, only the first on-off valve 12 is opened, and in the high rotation range, the first on-off valve 1 is opened.
The switching control is performed in four stages in which both the second and second on-off valves 14 are opened. More specifically, as shown in FIG. 1, the first on-off valve 12 is connected to a surge tank 6 side communicating portion in the second intake passage 10 at the junction of the surge tank 6 and the second intake passage 10. 10-1 and the second on-off valve 14 is provided in the first
The first intake passage 8 side communication portion 10-2 is provided in the second intake passage 10 at the junction of the intake passage 8 and the second intake passage 10. The first on-off valve 12 and the second on-off valve 14 are opened and closed by an actuator (not shown) controlled by a signal from control means (also referred to as "ECU") not shown. It is. In a low engine speed range, for example, below the engine speed N1, as the engine speed increases, at least one of the first opening / closing valve 12 and the second opening / closing valve 14 is closed, and the intermediate first speed region is closed. , For example, the engine speed N1
To N2, only the second on-off valve 14 is opened, and in the intermediate second rotation range above the intermediate first rotation range, for example, up to the engine speeds N2 to N5, the first on-off valve 1 is opened.
2 is opened, and the engine speed is high, for example, the engine speed N5.
In the above, both the first on-off valve 12 and the second on-off valve 14 are opened, and switching control is performed in four stages. Further, by opening the first on-off valve 12 and closing the second on-off valve 14 during the engine rotation speed N2 to N5, which is the intermediate second rotation range, as shown in FIG. Line segment D with respect to line segment C which is the torque characteristic of
Thus, the torque characteristics of the portion T3 indicated by the cross hatching can be improved. Further, as the engine speed increases,
Switching the opening and closing of the first on-off valve 12 and the second on-off valve 14 according to FIG. 5 makes it possible to improve the torque characteristics over the entire engine speed range. The first on-off valve 12 or the second on-off valve 12
When the on-off valve 14 is closed, only the first intake passage 8 functions as an intake passage, as shown in FIGS.
The intake passage 10 functions as a resonator.
In addition to the resonance of the intake passage 8 and the inertia supercharging effect, the resonance effect of the second intake passage 10 acts. At this time, the first on-off valve 12 and the second
Depending on which of the on-off valves 14 is closed, as shown in FIGS. 2 and 3, the mounting position of the second intake passage 10 changes, the resonance effect of the second intake passage 10 differs, and the torque curve is shown in FIG. It changes like the “O” and “□” marks. Next, the operation will be described. The first on-off valve 12 and the second on-off valve 14 are switched and controlled in four stages as the engine speed increases. First, a low engine speed range, for example, the engine speed N
1 or less, the first on-off valve 12 and the second on-off valve 1
At least one of the four is closed. At this time, when the first on-off valve 12 or the second on-off valve 14 is closed, only the first intake passage 8 functions as an intake passage, as shown in FIGS.
The second intake passage 10 functions as a resonator,
In addition to the resonance of the first intake passage 8 and the inertial supercharging effect, the resonance effect of the second intake passage 10 acts. Depending on which of the first on-off valve 12 and the second on-off valve 14 is closed, the mounting position of the second intake passage 10 changes as shown in FIGS.
The resonance effect of the second intake passage 10 is different, and the torque curve changes as indicated by “O” and “□” in FIG. Further, only the second on-off valve 14 is opened during an intermediate first rotation range, for example, between engine speeds N1 and N2. That is, during the engine speed N1 to N2, the second on-off valve 14 is opened and the first on-off valve 1 is opened.
As shown in FIG. 4, by closing line 2, line segment C, which is a conventional torque characteristic, is maintained, and the torque characteristic of a portion T2 indicated by oblique lines with respect to line segment D is improved. Further, only the first on-off valve 12 is opened in the intermediate second rotation range, for example, between engine speeds N2 and N5. That is, by opening the first on-off valve 12 and closing the second on-off valve 14 during the engine rotation speeds N2 to N5, as shown in FIG. The line segment D becomes a line segment D with respect to the segment C, and the torque characteristic of the portion T3 indicated by the cross hatching is improved. Further, in a high rotation range, for example, at an engine speed N5 or more, the first on-off valve 12 and the second on-off valve 14
And open both. That is, when the engine speed is equal to or higher than N5, by opening both the first opening / closing valve 12 and the second opening / closing valve 14, the passage length becomes short and the cross-sectional area becomes large, as shown in FIG. , A line segment E as a torque characteristic is secured. Conventionally, a first intake passage communicating between the surge tank and the intake hole of the cylinder head and a first intake passage branching from an intermediate portion of the first intake passage and communicating with the surge tank.
In an engine intake device provided with a second intake passage communicating with a passage length shorter than the intake passage and an on-off valve for opening and closing the second intake passage in accordance with the engine speed, the on-off valve is connected to the second intake passage.
Only one location is provided in the surge tank-side communication portion of the intake passage, and the on-off valve is closed in a low engine speed region to use a first intake passage having a small cross-sectional area and a long pipe length, and a high engine speed region. In the Japanese Patent Application Laid-Open No. H08-157, the on-off valve is opened, the cross-sectional area is large, and the pipe is switched to the two-stage using the second intake passage using the second intake passage having a short pipe length to increase the charging efficiency and improve the engine torque. On the other hand, according to the embodiment of the present invention, the communication portion 1 of the second intake passage 10 on the surge tank 6 side is provided.
A first opening / closing valve 12 is provided at 0-1 and a second opening / closing valve 14 is provided at the first intake passage 8 side communication portion 10-2. Then, the first on-off valve 12 and the second on-off valve 1
4, at least one of the second on-off valves 14 is opened during the intermediate first rotation range, for example, between the engine speeds N1 and N2, and the intermediate second rotation range, for example, the engine speeds N2 to N5. Up to this point, only the first on-off valve 12 is opened, and in a high rotation region, for example, at an engine speed N5 or more, switching control is performed in four stages in which both the first on-off valve 12 and the second on-off valve 14 are opened. In particular, the intermediate second
The second intake passage 10 can function as a resonator of the surge tank 6 in the rotation range, and the intake air charging efficiency in the intermediate rotation range can be further increased and the engine torque can be improved as compared with the conventional case. Things. It should be noted that the present invention is not limited to the above-described embodiment, and various application modifications are possible. For example, in the embodiment of the present invention, in the opening / closing control of the first and second on-off valves, two types of "open" and "closed" are performed. It is also possible to adopt a special configuration for finely controlling the opening and closing of the device. That is, for example, a "half open" state is added to the first and second on-off valves to open, half open, and close.
And the opening and closing control of the first and second on-off valves. The open / close states of the first and second on-off valves may be not only the above three types but also four or more types. Then, the intake flow rate is adjusted by the "half opening", and the first and second operation modes corresponding to various operation ranges are performed.
More detailed opening / closing control of the second opening / closing valve becomes possible. In the embodiment of the present invention, the first
Although an intake passage and a second intake passage branching from an intermediate portion of the first intake passage and communicating with the surge tank with a shorter passage length than the first intake passage are provided, the number of intake passages is reduced. It is also possible to adopt a special configuration of three or more. That is, for example, when the number of intake passages is three, as shown in FIG. 6, a first intake passage 8 is provided, and a surge tank is branched from an intermediate portion of the first intake passage 8. The second intake passage 10 is provided between the first and second intake passages 8 and 10 and communicates with the first intake passage 8 with a passage length shorter than the first intake passage 8. A third branch that branches off from an intermediate portion of the first intake passage 8 located upstream and communicates with the surge tank 6 with a passage length shorter than the first intake passage 8 and longer than the second intake passage 10. An intake passage 22 is provided. A third opening / closing valve 24 is provided in the communication portion 22-1 on the surge tank 6 side of the third intake passage 22, and a fourth opening / closing valve 2 is provided in the communication portion 22-2 on the first intake passage 8 side.
6 for controlling the opening and closing of the first to fourth on-off valves 12, 14, 24, 26 as the engine speed increases. Then, three first to third intake passages 8, 10, and 22 having different passage lengths are formed, and the second to third intake passages are formed.
First and second on-off valves 12 and 14 for opening and closing the intake passage 10 and third and fourth on-off valves 24 and 2 for opening and closing the third intake passage 22
6 are formed, and the first to fourth on-off valves 12,
By controlling the opening, closing, and opening of 14, 24 and 26, there are many variations in the effects that can be secured, which is practically advantageous. As described above in detail, according to the present invention, the first intake passage communicating between the surge tank and the intake hole of the cylinder head, and a branch from the intermediate portion of the first intake passage. A second intake passage communicating with the surge tank with a passage length shorter than the first intake passage, and an on-off valve for opening and closing the second intake passage in accordance with the engine speed. A first opening / closing valve is provided at a surge tank side communication portion of the second intake passage, and a second opening / closing valve is provided at the first intake passage side communication portion. At least one of the valve and the second on-off valve is closed, only the second on-off valve is opened in the intermediate first rotation range, only the first on-off valve is opened in the intermediate second rotation range, and the first is opened in the high rotation range. Open both on-off valve and second on-off valve 4 By performing the switching control in stages, the second intake passage can function as a resonator of the surge tank particularly in the intermediate second rotation range, and the intake charging efficiency in the intermediate rotation range can be further improved as compared with the conventional one. Thus, the engine torque can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an intake device for an engine showing an embodiment of the present invention. FIG. 2 is a schematic explanatory view showing an operation example when a first on-off valve is closed. FIG. 3 is a schematic explanatory view showing an operation example when a second on-off valve is closed. FIG. 4 is a diagram showing an effect of the engine speed in each rotation range. FIG. 5 shows first and second engine rotation speeds in respective rotation ranges.
It is a figure which shows the opening and closing state of an on-off valve, and the torque improvement effect. FIG. 6 is a configuration diagram of an intake device for an engine showing another first embodiment of the present invention. FIG. 7 is a configuration diagram of an intake device for an engine showing a conventional technique of the present invention. FIG. 8 is an explanatory diagram showing a flow of intake air when the on-off valve is closed. FIG. 9 is an explanatory diagram showing a flow of intake air when the on-off valve is opened. [Description of Signs] 2 Engine intake device 4 Intake manifold 6 Surge tank 8 First intake passage 10 Second intake passage 10-1 Surge tank 6 side communication portion 10-2 First intake passage 8 side communication portion 12 First opening / closing Valve 14 Second on-off valve

Claims (1)

Claims: 1. A first intake passage communicating between a surge tank and an intake hole of a cylinder head, and a branch from an intermediate portion of the first intake passage and a connection between the surge tank and the first intake passage. A second intake passage communicating with a passage length shorter than the first intake passage is provided,
In an intake system for an engine provided with an on-off valve for opening and closing the second intake passage in accordance with the engine speed, a first on-off valve is provided in a surge tank-side communication portion of the second intake passage, and the first intake passage is provided. A second on-off valve is provided in the side communication portion,
In a low rotation range with an increase in engine speed, at least one of the first on-off valve and the second on-off valve is closed,
Only the second on-off valve is opened in the intermediate first rotation region, only the first on-off valve is opened in the intermediate second rotation region, and both the first and second on-off valves are opened in the high rotation region. An intake device for an engine, wherein the intake control device performs switching control in four stages.