JPH04209961A - Intake device for internal combustion engine - Google Patents

Abstract

PURPOSE:To effectively eliminate an impure feeling of an intake air noise by providing an expansion chamber, whose sectional area is spread, in an intake pipe between a throttle valve and a surge tank. CONSTITUTION:In an intake system of an internal combustion engine, an air cleaner 2, intake pipe 4, surge tank 6 and intake manifolds 8 are successively arranged by this order in a flow direction of intake air, and the intake manifolds 8 are connected to an intake air port of the internal combustion engine 10 to provide a throttle valve 12 in the intake pipe 4. Here, an expansion chamber 14, whose sectional area is spread larger than the sectional area of the intake pipe, is provided in the intake pipe 4 between the throttle valve 12 and the surge tank 6. A diameter D of this expansion chamber is larger than a diameter (d) of the intake pipe, and the diameter D is preferably set to 4 times or more the diameter (d). In this way, impurity of an intake air noise is eliminated to improve a quality of in-car noise.

Description

[Detailed description of the invention]

[00011

[Industrial Field of Application] The present invention relates to an intake system for an internal combustion engine that can eliminate the muddy feeling of intake noise. [0002] Conventionally, the intake system configuration of an internal combustion engine has been designed primarily to improve output, and the configuration aimed at increasing output often causes noise aggravation. The demands for countermeasures against this noise are changing from "reducing the level" to "improving the sound quality" as automobiles are required to have higher quality. It is said that one of the causes of the so-called intake rumbling noise, which muddies the sound inside the car and deteriorates the sound quality, is that the length from the port of each cylinder to the throttle valve varies greatly between cylinders. . It is technically and productively possible to match the length from the port portion of each cylinder to the throttle valve for each cylinder. For example, this can be achieved by extending branch pipes of the intake manifold from one location of the surge tank and matching the lengths of the branch pipes. However, such a configuration causes a decrease in the output of the internal combustion engine and has limitations on vehicle mounting space, so it has not been put into practice. From the above, in the example of a mass-produced internal combustion engine, the poor sound quality can be compensated for by increasing the volume of the air cleaner, installing a resonator, or installing a resonant diaphragm as in Japanese Utility Model Application Publication No. 2-80710. This is countered by reducing the amplitude of air column pulsations. [0003]

[Problem to be Solved by the Invention] However, with conventional countermeasures, although the level of intake air turbidity sound (intake rumbling sound) can be reduced by reducing the amplitude of air column resonance, air column pulsation still exists. Therefore, it is impossible to essentially eliminate the muddiness of the intake sound. [00041] An object of the present invention is to provide an intake system for an internal combustion engine that can essentially eliminate the muddy feeling of intake noise. [0005]

[Means for Solving the Problems] An intake system for an internal combustion engine according to the present invention for achieving the above object comprises the following device. In other words, in an internal combustion engine intake system that includes an air cleaner, an intake pipe with a throttle valve in the middle, a surge tank, and an intake manifold, the cross-sectional area of the intake pipe between the throttle valve and the surge tank is expanded. An internal combustion engine intake system with an expansion chamber. [0006]

[Operation] It is thought that the provision of the expansion chamber prevents the standing waves inside the surge tank, which are the main cause of the generation of intake air muddy sound, so that the air intake sound's muddy feeling essentially disappears. [0007] Embodiment 1 Below, a preferred embodiment of the intake system for an internal combustion engine according to the present invention will be described with reference to the drawings. Figure 2 shows the overall configuration of the intake system. The intake system of an internal combustion engine includes an air cleaner 2, an intake pipe 4, and a surge tank 6 in the direction of intake air flow.
, the intake manifold 8, and the intake manifold 8.
is connected to the intake port of the internal combustion engine 10. A throttle valve 12 is provided in the intake pipe 4. Intake manifold branch pipes connected to each cylinder are connected to the surge tank 6 in a line in the axial direction, with the tip end serving as the first cylinder. The surge tank 6 is parallel to the internal combustion engine 10 and therefore the lengths of each branch of the intake manifold 8 are equal or approximately equal. As shown in FIG. 1, the intake pipe 4 between the throttle valve 12 and the surge tank 6 is provided with an expansion chamber 14 whose cross-sectional area is larger than the cross-sectional area of the intake pipe. The diameter of the expansion chamber is larger than the diameter d of the intake pipe, and D is desirably set to four times or more of d. If D is smaller than 4d, the effect of the expansion chamber 14, which will be described later, will be weakened. Also,
The diameter of the surge tank 6 is larger than the diameter of the intake pipe 4 but much smaller than the diameter of the expansion chamber 14. [00081 Next, the operation will be explained. When we analyzed the intake air turbidity noise that deteriorates the sound quality inside a car, we found that the amplitude of the envelope of the time-sound pressure level curve fluctuates, and a wave whose wavelength is 2922 revolutions above is generated, as shown in Figure 3. It turned out that this is true. Even at the same sound pressure level, when the envelope is almost constant as shown in FIG. 4, there is no muddy feeling. In order to elucidate the mechanism by which the intake air muddy noise shown in Figure 3 occurs in the intake pipe, we actually measured the pressure inside the intake pipe, and found that the surge tank and the intake pipe (air cleaner hose) act as a single pipe, as shown in Figure 5. Then, a standing wave with a total length of 3/4 wavelength is generated in the internal air column,
The antinode of the mode was at the tip of the closed end of the surge tank, and it was discovered that this standing wave was the cause of the intake air muddy noise. For more details, see the first section on the closed end side of the surge tank.
When the No. 1 cylinder is in its intake stroke, it emits an intake sound with the highest sound pressure level, and the other cylinders emit sounds with a lower sound pressure level, and once every 2922 revolutions, the No. 1 cylinder emits an intake sound with the highest sound pressure level. An intake stroke occurs and a muddy sound as shown in Fig. 3 is generated. This finding is also consistent with the fact that the cause of intake rumbling noise is that the length from the port of each cylinder to the throttle valve differs between cylinders. In order to prevent this air intake noise,
Conventionally, as shown in Figure 6, the sound pressure level was lowered by installing a resonator, etc., but since standing waves still exist, this only reduces the strength of the intake air turbidity sound, and solves the fundamental problem. It didn't solve the problem. [0009] However, in the present invention, by providing the expansion chamber 14 in the intake pipe 4 between the throttle valve 12 and the surge tank 6, the air column pulsation in the intake pipe becomes as shown in FIG. 7, and a standing wave is generated. Disappear. From engine speed, 200
Although the sound in the frequency range of ~800Hz is a problem, expansion room 1
4, the intake pipe of the actual size has a substantially open end on the expansion chamber 14 side and a closed end on the closed end of the surge tank. Only pulsation occurs, and in the mode of air column pulsation as shown in FIG. 7, the sound inside the car becomes a sound wave whose envelope does not have waves as shown in FIG. 4, and there is no muddy feeling. Further, on the path where the intake noise travels from the surge tank 6 to the air cleaner 2, the intake noise is attenuated in the expansion chamber 14, and even if some turbidity remains, it is significantly reduced. in this case,
If the diameter of the expansion chamber 14 is four times or more the diameter d of the intake sensation 4, the expansion chamber 14 has an opening effect. A test was conducted to determine whether or not the engine output would be reduced by providing the expansion chamber 14 as described above, and the results shown in FIG. 1 were obtained. As seen in Fig. 8, the engine rotation speed is in the normal use range,
For example, it has been found that at rotational speeds below about 3200 rpm, the shaft torque of the shaft with the expansion chamber is improved compared to the shaft torque of the shaft without the expansion chamber, and at rotational speeds higher than that, the shaft torque only slightly deteriorates. Therefore, no problem arises in terms of output. [00101] [Effects of the Invention] According to the intake system for an internal combustion engine according to the present invention, since an expansion chamber with an enlarged cross-sectional area is provided in the intake pipe between the throttle valve and the surge tank, the muddy intake sound can be reduced. It is possible to eliminate the feeling of noise and improve the sound quality of the sound inside the car.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an intake system for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a perspective view of an intake system for an internal combustion engine according to an embodiment of the present invention.

FIG. 3 is a time-sound pressure level diagram of intake sound with a muddy feeling.

FIG. 4 is a time-sound pressure level diagram of intake sound without muddiness.

FIG. 5 is a standing wave mode diagram in the intake pipe of a muddy intake sound.

FIG. 6 is an air column pulsation distribution diagram in the intake pipe when a resonator is installed.

FIG. 7 is an air column pulsation distribution diagram in the intake pipe according to the present invention.

FIG. 8 is an engine rotation speed-shaft torque characteristic diagram in the present invention.

[Explanation of symbols]

2 Air cleaner 4 Intake pipe 6 Surge tank 8 Intake manifold 10 Internal combustion engine 12 Throttle valve 14 Expansion room

[Figure 6]

Claims (1)

[Claims] Claim 1: In an intake system for an internal combustion engine comprising an air cleaner, an intake pipe with a throttle valve disposed in the middle, a surge tank, and an intake manifold, the intake pipe between the throttle valve and the surge tank has a cross-sectional area. An intake system for an internal combustion engine, characterized by having an enlarged expansion chamber.