JPS6318755Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an intake noise prevention device for an internal combustion engine that performs resonance supercharging. In the case of this type of internal combustion engine, especially an engine with four or fewer cylinders, pressure pulsations are not smoothed out at the intake manifold junction where the intake pulses of all cylinders join, and in the intake system upstream from this. There was a problem in that the intake noise was louder than that at the open end. In addition, when performing resonant supercharging in this type of engine, the entire intake system must be designed as a resonant supercharging passage, which makes it difficult to set the matching point, and the effect of the intake throttle in the air cleaner makes resonant supercharging difficult. The supercharging effect is reduced. In order to solve these problems, by providing a surge tank in the middle of the engine intake passage, pressure pulsations within the surge tank are smoothed out, and
It would be possible to configure a resonant supercharging passage downstream of the surge tank, but in this case, the volume of the surge tank would need to be more than 10 times the volume of the cylinder, which would require a considerable amount of space. . For this reason, conventionally, as shown in FIG. 1, a Helmholtz resonator A consisting of a resonance tube 2 and a resonance container 3 is connected and merged in the middle of an engine intake passage 1, and a resonance tube 5 and a manifold container are connected downstream of this junction 4. In addition to providing a resonant supercharging passage B consisting of 6 etc., the resonant frequencies of the Helmholtz resonator A and the resonant supercharging passage B are matched to eliminate the influence of an air cleaner etc. on resonance supercharging and reduce intake noise. (Japanese Unexamined Patent Publication No. 55-87822). However, in Helmholtz resonator A of this conventional device, the resonant frequency does not change, and its vibration absorption effect is effective only in the vicinity of the resonant frequency. Therefore, in a region away from the engine rotational speed region corresponding to this resonance frequency, the intake vibration frequency deviates from the resonance frequency of the resonator A, so that the vibration absorption effect is significantly reduced. Therefore, in an automobile internal combustion engine having a wide normal engine rotation range, the effect of reducing intake noise cannot be said to be sufficient. This idea was made in view of the above circumstances.
In the middle of the engine intake passage, there is an inner cylinder and an outer cylinder that are overlapped so as to be relatively movable, and the inner cylinder and the outer cylinder are moved relative to each other by fluid pressure introduced into a sealed annular gap formed in the overlapping part. By connecting a Helmholtz resonator whose resonant frequency increases as the engine speed increases, the intake passage on the downstream side of this connection becomes a resonant supercharging passage, and the resonant frequency of the Helmholtz resonator becomes a resonant supercharging passage. The object of the present invention is to solve the conventional problems by configuring the vibration frequency to change substantially in accordance with the change in the intake vibration frequency. Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In FIG. 2 showing the first embodiment, the engine body 1
An intake duct 14 is connected to the intake manifold 12 connected to the air intake duct 14 and is opened to the atmosphere via an air cleaner 13.
Connect. A Helmholtz resonator 15 is connected between the air cleaner 13 of the intake duct 14 and the intake manifold 12, and the Helmholtz resonator 15 is configured so that its resonant frequency increases as the engine rotational speed increases. In this case, the intake duct downstream of the connection part 14a of the resonator 15 is a resonance pipe 14b, and this resonance pipe 1
4b and the intake passage downstream of the connecting portion 14a is defined as a resonant supercharging passage. 23 is an exhaust manifold. FIG. 3 shows details of the structure of the Helmholtz resonator. In the figure, this Helmholtz resonator 1
5 is composed of a resonance tube 16 and a resonance container 17. The resonance container 17 has a fixed container 17A as an outer cylinder to which the resonance tube 16 is connected, and a movable container 17B as an inner cylinder that is slidably overlapped with the fixed container 17A. A spring 18 is interposed between the fixed container 17A and the inner surface of the resonance tube connection portion of the fixed container 17A. Moreover, a seal member 20 for sealing a gap 19 formed by overlapping both containers 17A and 17B is attached to the inner peripheral edge of the opening of the fixed container 17A and the outer peripheral edge of the opening of the movable container 17B. For example, engine lubricating oil is introduced into the gap 19 through a pipe 21, the pressure of which increases as the engine rotational speed increases. Next, the action will be explained. When the oil pressure of the lubricating oil introduced into the gap 19 through the piping 21 increases as the engine rotational speed increases, the movable container 17B slides to the left in FIG. 3 against the elastic force of the spring 18. do. Therefore, the volume of the resonance container 17 becomes smaller. The resonant frequency ₁ of the Helmholtz resonator 15 is given by the following formula: If the cross-sectional area of the resonant tube is A ₁ , the length is L ₁ , and the volume of the resonant container is V ₁

It is given by [Formula] (K is a coefficient). Therefore, the resonant frequency of the Helmholtz resonator 15 increases continuously as the engine rotational speed increases. The change in resonance frequency is configured to increase while substantially matching the intake vibration frequency in the resonance supercharging passage, which increases as the engine rotational speed increases. Therefore, over a wide range of engine rotational speeds, intake vibrations are not transmitted into the intake duct 14 upstream of the connecting portion 14a, and the vibration absorption effect of the Helmholtz resonator 15 can be effectively applied, significantly reducing intake noise. can be reduced to Moreover, by applying lubricating oil pressure to the gap 19 between the fixed container 17A and the movable container 17B, the internal volume of the Helmholtz resonator 15 is varied, so that the engine rotation speed is reduced in a supercharged internal combustion engine. Even if the resonator 15 is placed on the downstream side of the supercharger where the supercharging pressure that increases as the number of resonators increases, the internal volume of the resonator 15 can be reduced by overcoming the supercharging pressure when the engine rotation increases. Therefore, it can be applied as is to a supercharged internal combustion engine. Further, the resonant frequency of the Helmholtz resonator 15 is made to match the resonant frequency of the resonant supercharging passage at the mutual engine rotation speed of the mutual supercharging. Furthermore, the resonance frequency of the Helmholtz resonator may be changed by making the length of the resonance tube variable. For example, as shown in FIGS. 4 and 5, a resonance pipe 16 of a Helmholtz resonator 15 is provided inside a merging section 25 where the intake manifold 12 connected to the engine body 11 merges. As shown in FIG. 6, a fixed tube 16A connects this resonance tube 16 to a resonance container 17, and a movable tube 1 slideably overlaps with the fixed tube 16A.
6B, and engine lubricating oil is supplied through a pipe 21 to the gap 19 formed by the polymerization. In this case, when the oil pressure in the gap 19 increases as the engine rotational speed increases, the movable tube 16B moves to the left in FIG. 6 against the spring 18, and the length of the resonance tube 16 becomes shorter. Helmholtz resonator 1
5 resonance frequency increases with increasing engine speed. As described above, according to the present invention, the resonant frequency of the Helmholtz resonator is increased in accordance with an increase in engine rotational speed, and this resonant frequency is increased while substantially matching the intake vibration frequency in the resonant supercharging passage. With this configuration, intake noise can be effectively reduced over a wide range of engine operating ranges, and the intake noise reduction effect can be greatly improved. In addition, in a Helmholtz resonator, an inner cylinder and an outer cylinder that are movable relative to each other are overlapped, fluid pressure is introduced into a sealed annular space between the overlapping parts, and the resonant frequency is made variable by using this fluid pressure to move both cylinders relative to each other. Because of this structure, even if it is installed downstream of the supercharger where supercharging pressure acts in a supercharged internal combustion engine, it can be operated normally by the action of fluid pressure. It can also be applied to

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing a conventional example, Fig. 2 is a schematic plan view showing an embodiment of the present invention, Fig. 3 is an enlarged sectional view of the main part of the same embodiment, and Fig. 4 is a schematic diagram of the present invention. the second of
A schematic plan view showing the embodiment, FIG. 5 is in FIG.
The arrow view and FIG. 6 show a sectional view of a main part of the same embodiment. 12...Intake manifold, 14a...Connection part,
14b... Resonance tube, 15... Helmholtz resonator, 16... Resonance tube, 16A... Fixed tube, 16B
...Movable tube, 17... Resonance container, 17A... Fixed container, 17B... Movable container, 19... Gap part.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine having a resonant supercharging type intake passage, an inner cylinder and an outer cylinder are arranged in the middle of the engine intake passage and overlap each other so as to be relatively movable, and the fluid pressure introduced into a sealed annular gap formed in the overlap part is provided. Therefore, a Helmholtz resonator whose resonant frequency increases as the engine speed increases due to relative movement between the inner cylinder and the outer cylinder is connected, and the intake passage downstream of this connection is made a resonant supercharging passage. In addition, an intake noise prevention device for an internal combustion engine, characterized in that the resonant frequency of the Helmholtz resonator is configured to be approximately equal to the intake vibration frequency in the resonant supercharging passage.