JPH0629558B2 - Air intake device for engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake system, and more particularly, to a valve operating system noise at a relatively low rotational speed in a variable intake pipe length engine, The present invention relates to an improved intake device capable of attenuating impact noise caused by intake valve seating.

<Prior Art> An intake manifold that constitutes an intake device of an engine is generally connected between an intake port of a cylinder head and a carburetor or throttle body having a throttle valve for adjusting the intake air amount, and is used for combustion of the engine. It has a role of distributing and supplying necessary air into the intake port, and usually has the same number of branch passage pipes as the intake ports. With the increasing output of engines in recent years, the effective pipe length of the intake manifold is shortened at high rotation speed or high load to improve the intake charging efficiency over the entire operating range, thereby improving the output performance. A pipe length method has been proposed.

That is, in the intake port of the engine, the long pipe intake passage,
A short pipe intake passage provided in parallel with the long pipe intake passage and having a built-in bypass valve is connected, and the bypass valve is opened at a high load or a high rotation speed of the engine so that the low rotation speed or In the low load region, intake is performed in the long pipe intake passage, which has a relatively long pipe length, and in the high rotation or high load operating region, intake is performed in the short pipe intake passage, which has a relatively short pipe length. By utilizing the intake inertia effect at the time of load and by reducing the intake resistance at the time of high rotation speed or at the time of high load, the charging efficiency of the intake air is increased in any case, and it is intended to improve the output accordingly.

However, in such a variable intake pipe length type intake manifold, in the idling state, the long pipe intake passage is selected, and the reflected wave due to the impact sound of the intake valve seating generated in the idling state is the long pipe. Wave resonance occurs in the intake passage, which becomes one of the main noises in the idling state, and there is an inconvenience that it is not suitable for noise reduction in recent engines, especially passenger car engines.

<Problems to be Solved by the Invention In view of the above-mentioned problems of the prior art, a main object of the present invention is to cause a reflected wave of an intake valve seating impact sound in an idling state to cause wave resonance in the intake passage. An object of the present invention is to provide an engine intake device having an intake manifold of a variable intake pipe length system that is improved so as not to be a noise generation source.

<Means for Solving Problems> According to the present invention, such a purpose is to provide a throttle valve for controlling an intake air amount supplied to an intake port of an engine,
An enlarging chamber connected to the downstream side of the throttle valve, a long pipe intake passage and a short pipe intake passage connected in parallel between the enlarging chamber and the intake port of the engine, and an intermediate portion of the short pipe intake passage. In an engine intake device having an on-off valve provided, the on-off valve opens at a high load or a high rotation speed of the engine, and also opens near an idle rotation speed of the engine. It is achieved by providing an intake system for an engine. In particular, it is preferable to provide a hysteresis between the opening / closing operation of the open / close valve and the rotation speed of the engine.

<Operation> As described above, in a predetermined idling state, by opening the on-off valve to connect the short pipe intake passage, the pipe length of the intake passage can be shortened, so that the intake valve seating in the idling state can be shortened. It is possible to prevent the reflected wave due to the impact sound from causing wave resonance in the intake passage, and to prevent the generation of noise.

In addition, the resonance frequency can be adjusted by the volume of the huge chamber, and the frequency component which is offensive to the ears can be reduced. In addition to this, by providing a hysteresis in the operating speed of the bypass valve, it is possible to prevent the bypass valve from hunting.

<Embodiment> Hereinafter, the present invention will be described in detail with reference to a specific embodiment with reference to the accompanying drawings.

FIGS. 1 and 2 show an intake system having a variable pipe length intake manifold 1 in an intake passage of a multi-cylinder engine. In this intake manifold, a mounting flange 2 connected to a throttle body is shown. The inlet 3 is opened at the same time, and the mounting flange 4 is connected to the cylinder head.
The outflow portions 5a, 5 communicating with the intake ports are provided at a and 4b.
b, 5c, 5d, 5e and 5f are opened respectively. Further, a branch pipe 6 that defines an intake passage that connects the inflow port 3 and the outflow portions 5a to 5f is connected between the mounting flanges 2, 4a, and 4b.

In the branch pipe 6, an intake chamber 7 as an enlarged chamber having a relatively large predetermined volume and having a diameter larger than that of the inflow port 3 is defined in a portion adjacent to the downstream side of the inflow port 3. The intake chamber 7 and the inflow port 3 form an inflow portion.

In addition, bifurcated branch ports 9a to 9f are formed in communication with the upstream sides of the outflow portions 5a to 5f, respectively, and each of the branch ports is directed to the inflow port, and has a substantially straight tubular short pipe intake passage. 10a to 10f and bending long pipe intake passages 11a to 11
f are communicated in parallel. In FIG. 2, the branch port 9f is shown.
One of the short pipe intake passages 1 provided in parallel with each other.
A set of intake passages extending from 0f and the long pipe intake passage 11f to the intake chamber 7 is shown.

A butterfly valve 15 supported by a common valve shaft 14 is provided at a relatively downstream portion of the short pipe intake passages 10a to 10f.
On-off valves 12a to 12f composed of a to 15f are provided,
The valve shaft 14 can be driven by the valve drive device 13 via a link 16.

Next, the outline of the operation of this embodiment will be described.

According to the above-described intake device, the open / close valves 12a to 12f are opened at the time of high engine load or high rotation speed so that intake is performed in the short pipe intake passages 10a to 10f having a relatively short pipe length. In addition, the open / close valves 12a to 12f are closed in the medium rotation speed or low load region so that the long pipe intake passage 11 having a relatively long pipe length is obtained.
By inhaling at a to 11f and utilizing the intake inertia effect, in any case, it is intended to increase the charging efficiency of the intake and to improve the output accordingly. Further, according to the present invention, the on-off valves 12a to 12f are opened even when the rotation speed is reduced to near the low idle speed or lower. This is done by opening the bypass valves 12a to 12f so that the reflected wave of the impact noise of the intake valve seating in the idling state does not cause wave noise resonance in the long pipe intake passages 11a to 11f and become a noise generation source. By reducing the length, it is intended to avoid the resonance phenomenon.

That is, as shown in FIG. 3, when the engine speed is rising, the open / close valves 12a to 12f are set when the engine speed (Ne) is in a substantially idling state, that is, less than 850 rpm.
Is in a valve open state, and intake air is short pipe intake passages 10a to 10f.
Therefore, the resonance phenomenon described above is avoided. In the medium speed operation range of 850 rpm ≦ Ne <3500 rpm, the on-off valves 12a to 12f are closed, the intake air flows through the long pipe intake passages 11a to 11f, the intake inertia effect is obtained, and the high speed operation range Ne> At 3500 rpm, the on-off valves 12a to 12f are opened again, and the intake is short pipe intake passage 1
Intake resistance is reduced by passing through 0a to 10f.

Also, when the engine rotation speed is decreasing, Ne = 3
The on-off valves 12a to 12f are closed at 300 rpm, and N
The opening / closing valves 12a to 12f are opened at e = 1300 rpm, and a rotational speed hysteresis is provided at the operating point of opening / closing of the opening / closing valves 12a to 12f when the engine speed increases to stabilize the valve opening / closing operation. It is trying to make it.

In this case, if the rotational speed hysteresis is set too large, it will be unfavorable from the standpoint of charging efficiency of the intake air, so in consideration of both, the rotational speed hysteresis of the valve opening / closing operation in the high load region is set to 200 rpm.

In the above description, the open / close valve is opened / closed based only on the engine speed, but it is advisable to determine the open / close condition of the open / close valve in consideration of the load of the engine or the throttle valve opening. For example, the above idling state is N
It may be determined that this is the case where the conditions of e <1300 rpm, throttle valve opening <1.4 °, and cooling water temperature> 30 ° C. are satisfied.

As described above, in the idling state, the on-off valve 12a
To 12f open the valve so that the short pipe intake passage 10a
Since 10f to 10f are opened, the reflected wave due to the impact sound of the intake valve seat is prevented from causing wave resonance in the intake passage, and the generation of noise can be prevented. Therefore, for example, at a peak of 60 cm above the engine with the bonnet opened, a noise attenuation effect of -1.9 dB was obtained at the peak.

Moreover, in the present invention, the resonance frequency is adjusted by appropriately setting the volume of the intake chamber 7 so as to reduce the offensive frequency component. This can alleviate the unpleasantness in hearing.

<Effects of the Invention> As described above, according to the present invention, noise during idling of a variable intake pipe length type engine can be reduced by an extremely simple configuration, and therefore the effect is extremely large. In addition to this, by providing an appropriate hysteresis in the operating rotational speed of the on-off valve, the on-off valve can be stably opened and closed without causing hunting, so that no beating due to intermittent changes in sound pressure can be avoided. Therefore, it is effective in alleviating the discomfort of noise.

[Brief description of drawings]

FIG. 1 is a plan view of an intake system for an engine which is an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a graph showing the operation of the bypass valve. 1 ... Intake manifold, 2 ... Mounting flange 3 ... Inlet, 4a, 4b ... Mounting flange 5a-5f ... Inflow part, 6 ... Branch pipe 7 ... Intake chamber, 9a-9f ... Branch port 10a to 10f ... short pipe intake passage 11a to 11f ... long pipe intake passage 12a to 12f ... open / close valve 13 ... valve drive device, 14 ... valve shaft 15a to 15f ... valve body, 16 ... link

Claims (2)

[Claims] 1. A throttle valve for controlling the amount of intake air supplied to an intake port of an engine, an expansion chamber connected downstream of the throttle valve, and a parallel connection between the expansion chamber and the intake port of the engine. In an intake device for an engine having a long pipe intake passage and a short pipe intake passage, and an opening / closing valve provided in an intermediate portion of the short pipe intake passage, the opening / closing valve is a high load or a high load of the engine. An intake device for an engine, wherein the intake device for an engine is configured to open at a rotation speed and also open near an idle rotation speed of the engine. 2. The intake system for an engine according to claim 1, wherein a hysteresis is provided between the opening / closing operation of the opening / closing valve and the rotational speed of the engine.