JPH033068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resonator whose resonance frequency is varied in synchronization with the rotational speed of an internal combustion engine.

A conventional resonator was constructed as shown in FIG.
That is, the conventional resonator 18 is installed in the middle of the intake duct 13 and is connected to the inner intake passage 14 of the intake duct 13.
It consisted of a tubular member 15' that communicates with the resonator chamber 17, and a resonance chamber 17 that is open at the end surface of the tubular member 15'. The resonant frequency p of this resonator 18 is determined by p=C/2π·√ ₂ 4 (+0.8) (1).

Here, D is the inner diameter of the communicating tubular member 15', l is the length of the communicating tubular member 15', and V is the internal volume of the resonance chamber 17. Therefore, in a conventional resonator, the resonant frequency p is uniformly determined due to its structure.
The damping effect is obtained only at that specific resonance frequency p.

In contrast to conventional resonators that can obtain only a specific single resonant frequency, the present invention allows the resonant frequency to be varied by simultaneously changing the length l of the communicating tubular member expressed by equation (1) and the cross-sectional area of its opening. The aim is to expand the controllable frequency range.

That is, in order to change the resonant frequency p of the resonator in equation (1), it is sufficient to change the shape of the communicating tubular member, that is, the inner diameter D and length l of the tubular member, or the resonance chamber volume V. However, the volume of the resonance chamber is usually set as large as possible, and it is technically difficult to control the volume of the resonance chamber by making it variable. A configuration was adopted in which the area S (S=π/4D ₂ ) was changed.

An embodiment in which a resonator according to the present invention is used as an intake noise muffling device in an internal combustion engine intake system will be described below with reference to FIG. 1 in the figure is piston 2
The upper part of the cylinder head 3 is covered with a cylinder head 3, and the cylinder head 3 has an intake valve 4, an intake port 6 which is periodically opened and closed by an exhaust valve 5, and an exhaust valve. A mouth 7 is formed. The exhaust port 7 communicates with an exhaust pipe via an exhaust passage 8, and this exhaust pipe is provided with a muffler (not shown) for muffling exhaust noise.

On the other hand, the intake port 6 is connected to an air cleaner 11 that purifies intake air via an intake passage 9 and a carburetor 10 (the carburetor 10 does not exist in the case of a diesel vehicle). A suction pipe 12 is attached to the upstream end of the air cleaner 11, and an intake duct 13 is attached to the tip of this suction pipe 12.
is connected to the tip opening 13a of the intake duct 13.
is open to the atmosphere.

A tubular member 15 branches off in the middle of the suction pipe 12 or the suction duct 13 (intake duct 13 in this embodiment). One end of the tubular member 15 communicates with the suction passage 14 in the intake duct 13, and the other end opens into a resonance chamber 17 which is a closed space. The tubular member 15 has a tapered shape in which the opening area increases from one end to the other end. and,
The resonator 1 is formed by this tubular member 15 and the resonance chamber 17.
8 is formed. A movable member 16 having an outer wall having the same taper angle as the inner wall of the fixed tapered tubular member 15 is attached to the shaft of a linear actuator 19 fixed to the side of the resonator 18 facing the fixed tapered tubular member 15. It is fixed at 20. In addition, the intake duct 13, the fixed tapered tubular member 1
5, the movable member 16, and the resonance chamber 17 are resin molded products. Therefore, the intake duct 13, fixed tapered tubular member 15, and resonance chamber 17 are fixed by appropriate means such as adhesion, screwing, caulking, and welding.

The linear actuator 19 uses an actuator that can electrically easily and accurately control the position in the axial direction, such as a step motor. and an internal combustion engine rotation detector (not shown)
The control computer 21 calculates a resonance frequency synchronized with the engine rotation based on the rotation signal from the engine, and an electric signal based on the calculation is applied to the linear actuator 19. Therefore, the movable member 16 fixed to the shaft 20 of the actuator 19 moves up and down in the figure by an amount corresponding to the electrical signal from the computer 21.
Along with this movement, the cross-sectional area of the gap 22 surrounded by the inner wall of the fixed tapered tubular member 15 and the outer wall of the movable member 16 is variably controlled.

Next, a method of varying the resonance frequency using the resonator 18 will be explained.

Figure 3 shows the response of the resonance frequency to the change in the length l of the communicating tubular member when the resonance chamber volume V = 2000 c.c. and the opening cross-sectional area of the communicating tubular member S = 310 mm ² (1)
It is obtained from the formula, and Figure 4 shows the resonance chamber volume V
= 2000 c.c., and the length l of the communicating tubular member was 46 mm.

As is clear from FIGS. 3 and 4, in order to increase the resonance frequency, the communication tubular member 15
It is sufficient to shorten the length l and increase the opening cross-sectional area S.

Therefore, in the resonator 18 having the above configuration, as shown in FIG. 2, the communicating tubular member is formed into a fixed tapered tubular member 15, and a movable member 16 having the same tapered shape is disposed within this tubular member 15. By moving the movable member 16 up and down by the linear actuator 19, the substantial length l and the substantial opening cross-sectional area S of the communicating tubular member are simultaneously variably controlled.

This variable control will be explained in more detail using FIGS. 5 and 6. FIG. 5 shows the initial setting positions of the fixed tapered tubular member ₁₅ and the movable member 16 of the communicating tubular member. It is formed by a gap 22 in the outer wall. Therefore, the resonance frequency l at this time is the fixed taper tubular member 1.
5. Let the length l ₀ of the overlapping movable member 16 be the communicating pipe length l, and the average opening cross-sectional area of the gap between both tapered pipes S ₀
It is determined by setting S to the cross-sectional area of the communicating tube opening.
FIG. 6 shows the movable member 16 connected to the linear actuator 1.
9 shows the case where the moving member 16 is moved by X mm. In this case, the actual communication tube length l is the length l ₁ where the movable member 16 overlaps, and the actual communication tube opening cross-sectional area S is the gap S ₁ on the outer periphery of the movable member 16. becomes. Therefore, in this case, compared to the initial setting position, l ₁ < l ₀ and S ₁ > S ₀ ,
The resonant frequency will be higher than l obtained at the initial setting position.

In this way, the variable range of the resonant frequency is determined by the linear actuator 19 that moves the movable tapered tubular member from the lower limit resonant frequency l determined by the initial setting position.
Upper resonant frequency defined by stroke change amount
It can be changed up to h.

Figure 7 shows the volume V of the resonance chamber 17 = 2000 c.c., and the diameter of one end of the fixed tapered tubular member 15 (as shown in Figure 8).
Dp=20mm, length lp of fixed tapered tubular member 15=
40 mm, and the taper angle θ of the fixed tapered tubular member 15 is 40° and 60°,
These are the results of an experiment in which the resonance frequency was measured while varying the stroke X of the movable member 16. As is clear from this experimental result, the larger the taper angle θ, the larger the change in resonance frequency with respect to the moving stroke X.
The one with a taper angle of 60° has a resonance frequency of 50Hz at 20mm.
It can be changed from 180Hz to 180Hz. That is,
In this example, since the actual length l and the actual opening cross-sectional area S of the communicating tubular member are simultaneously variably controlled in the displacement range of the required resonance frequency, the amount of change in the stroke X of the movable member 16 can be made small. Can be done.

As is clear from the above description, the variable range of the resonant frequency of the resonator 18 of this example is determined by the movement stroke X of the movable member 16, but it is also determined by the specifications shown in FIG. By appropriately selecting the height lp of the fixed tapered tubular member, its opening diameter Dp, and the resonance chamber volume V, it is possible to tune the variable range of the resonance frequency to a desired range even with the same moving stroke amount X.

Next, an example will be described in which the resonator 18 that performs the above operation is actually used in synchronization with the rotational speed of the internal combustion engine.
As shown in FIG. 2, a rotation signal of the internal combustion engine (obtained from a distributor or a crank pulley, for example) is input to a control computer 21 using a microcomputer, and the engine rotation speed is read within the computer 21. and,
A drive signal is sent to the actuator and the movable member 16 is slid through the shaft 20 to change the resonance frequency so that a resonance frequency corresponding to the frequency component is obtained. The above control flowchart is shown in FIG.

In order to control in this way, the linear actuator 19
can be moved in the forward and reverse directions so that the resonant frequency can be varied in synchronization with the rotational speed. In addition, as a synchronization signal for the engine speed, the first
As shown in Figure 0, the resonant frequency variable range from l to h can be linearly and continuously synchronized with respect to the engine speed, or can be synchronized stepwise, or synchronized freely by the control computer.

FIG. 11 shows the effect of reducing intake noise by using the resonator 18 in an internal combustion engine (4-cycle, 4-cylinder). The thin line A in the figure represents intake noise when the resonator 18 is not installed, and there is a large noise peak around 4000 to 4800 rotations, which is a problem. This noise peak is the second-order component of the engine speed, i.e.
133Hz to 160Hz is dominant. Therefore, resonator 1
The resonant frequency variable range of 8 was selected to be variable from 100Hz to 160Hz with the taper angle θ = 60° and the stroke amount of the linear actuator 19 = 10mm as shown in Fig. 7, and the engine speed was 3000. 4800 from rotation
By synchronously varying up to the rotation, intake noise can be significantly reduced in the rotation range, as shown by the bold line C in the figure, compared to the conventional resonator installation (dotted chain line B in the figure).

Note that the resonator 18 of this example can also provide the following effects.

In other words, it is well known that if the natural resonance frequency of the intake air intake passage pipe with the intake diameter matches the opening/closing frequency of the intake valve, a large amount of mixed gas (fuel and intake air) will be sucked into the cylinder. Therefore, conventionally, the length of the intake pipe is selected so as to obtain resonance at a certain rotation speed of the internal combustion engine, thereby increasing the engine output at that rotation speed. Therefore, by installing a resonator 18 in the middle of the suction pipe and making the resonant frequency variable, the natural resonance frequency of the entire suction pipe can be changed and synchronized with the opening/closing timing of the intake valve 4. It can also be used as a means to increase output in the rotation range.

Note that, although the above-mentioned examples are desirable embodiments of the present invention, the present invention has various embodiments other than the above-mentioned examples.

That is, in the above example, the linear actuator 19
is attached to the resonator, but it may also be attached to the intake duct 13 side as shown in FIG. Furthermore, the 13th
As shown in the figure, it is also possible to separate the resonator mounting part 23 from the intake duct 13 in consideration of the ease of mounting, so that its mounting position can be changed freely.

Further, in the above example, only one resonator 18 was provided, but as shown in FIG. 14, a plurality of resonators 18 may be provided. When a plurality of resonators 18 are provided in this way, the resonance chamber volume V, the opening area S of the communicating tubular member, or the length l of the communicating tubular member (volume U in the example shown in FIG. 14) of each resonator 18 are different from each other. By doing so, the resonant frequency range that can be controlled can be expanded.

Furthermore, in the above embodiment, the resonator 18 was arranged in the intake system and used as an intake noise reduction means, but a resonator with the same configuration could also be arranged in the exhaust system and implemented as an exhaust noise reduction device. A similar effect can be achieved.

As explained above, the resonator of the present invention has a double structure of a fixed tapered tubular member and a movable member, in contrast to the conventional communicating tubular member, so that the gap between the two members is used as a communication passage. and the movable member is moved in conjunction with the actuator to simultaneously change the substantial length and the substantial opening cross-sectional area of the communication passage (shorten the substantial length and increase the substantial opening cross-sectional area at the same time); The resonance frequency can be greatly variably controlled with a small amount of stroke change of the actuator. Furthermore, since the actuator is controlled by a control computer so that it can be driven in synchronization with the internal combustion engine speed, it is possible to synchronize the resonance frequency with the engine speed and significantly widen the engine speed range in which a damping effect can be obtained. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional resonator, Fig. 2 is a sectional view showing an embodiment of the resonator of the present invention installed in an internal combustion engine, and Fig. 3 is a resonator communication tubular member length and resonance. Figure 4 is an explanatory diagram showing the relationship between resonator communication tubular member opening cross-sectional area and resonance frequency. Figures 5 and 6 are diagrams showing changes in resonance frequency of the resonator shown in Figure 2. Sectional view showing the state, No. 7
The figures are explanatory diagrams showing the relationship between the movement stroke of the movable member of the resonator shown in Figure 2 and the variable frequency, Figure 8 is a sectional view showing the specifications of the resonator shown in Figure 2, and Figure 9 is the diagram shown in Figure 2. Illustrated resonator control flowchart, 1st
Figure 0 is an explanatory diagram showing a method of synchronizing the engine speed and resonance frequency, Figure 11 is an explanatory diagram showing the effect of reducing intake noise of the resonator shown in Figure 2, Figures 12, 13,
FIG. 14 is a sectional view showing other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1...Internal combustion engine cylinder, 3...Cylinder head, 4...Intake valve, 5...Exhaust valve, 6...Intake port, 9...Intake passage, 12...Intake pipe, 13...
Intake duct, 14... Suction path, 15... Fixed taper tubular member, 16... Movable member, 17... Resonance chamber, 18... Resonator, 19... Linear actuator, 20... Linear actuator shaft,
21...Control computer.

Claims (1)

[Scope of Claims] 1. A fixed tapered tubular member having one end open to a passage communicating with a cylinder of an internal combustion engine, a resonance chamber consisting of a sealed space communicating with the other end of the fixed tapered tubular member, and a resonance chamber formed within the fixed tapered tubular member. a tapered movable member slidably disposed on the movable member; an actuator that displaces the movable member based on an electric signal; and an actuator that detects the rotational speed of the internal combustion engine and controls an electric signal output to the actuator. A resonator comprising a control computer. 2. The device according to claim 1, wherein one end of the fixed tapered tubular member opens into an intake duct, and the control computer outputs an electric signal to the actuator to obtain a resonance frequency corresponding to the rotation speed of the internal combustion engine. resonator. 3. One end of the fixed tapered tubular member opens into an intake pipe, and the control computer outputs an electrical signal to the actuator to obtain a resonant frequency corresponding to an opening/closing frequency of an intake valve of the internal combustion engine. Resonator according to item 1.