JPH05955U - Resonator in intake device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a resonator capable of producing an excellent effect of reducing intake noise over a wide operating range of an engine. In a resonator in which a resonance chamber is connected to an intake pipe of an engine via a communication pipe having a small diameter, an inner pipe is fitted into the communication pipe so as to be slidable in an axial direction,
The intake pipe and the resonance chamber are configured to change the length of the inlet passage by displacing the inner pipe in the axial direction according to the engine speed. With this configuration, the resonance frequency can be changed over a wide operating range of the engine, and the intake noise can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a resonator in an intake system of an engine.

[0002]

[Prior Art]

 A resonator having a common chamber having a constant volume, which is connected to an intake pipe of an engine through a communication pipe having a small diameter, is known. Now, a typical configuration of a resonator mounted on a conventional intake system for a truck engine will be described with reference to FIG. 1 showing an embodiment of the present invention for the sake of convenience. A lower intake pipe made of resin mounted on a chassis frame (not shown), the lower intake pipe being an upper intake pipe attached to a rear wall of a cabin (not shown) mounted on the chassis frame. An intake inlet 16 connected to the pipe 12 through a flexible bellows pipe 14 and an intake outlet 18 connected to an air cleaner (not shown) are provided, and the bellows pipe 14 is properly connected to the intake inlet 16. A guide 20 is provided for this purpose. A resonance chamber 24 is connected to the lower intake pipe 10 via a communication pipe 22 having a small diameter. The communication pipe 22 does not include an inner pipe 26 (details of which will be described later) shown by a dotted line in the drawing, and is a simple circular pipe having a constant length in the past. Reference numeral 24 is an integrally molded container having a constant volume.

As is well known in the art, the resonance frequency f of the resonator 28 including the communication pipe 22 having the small diameter and the resonance chamber 24 as described above is represented by the following formula 1.

[0004]

[Equation 1]

In the above formula 1, C is the speed of sound, d is the inner diameter of the communication pipe 22, l is the length of the small-diameter inlet passage in the communication pipe 22, and V is the volume of the resonance chamber 24. This resonator 28 can exert an excellent sound deadening effect only in an extremely narrow region near the resonance frequency f 1 expressed by the equation 1, and like the engine for a truck, it has a wide rotation speed from the idle speed to the maximum speed. For an engine operating within the range, the effect of reducing intake noise can be expected only near a predetermined rotational speed that is adjusted in advance. Further, the resonator 28 is often made of a resin material like the intake pipe 10 described below. In this case, in order to manufacture a plurality of types of resonators which are suitable for a plurality of engines having different specifications, Since a large number of molding dies that are essentially expensive must be prepared, the manufacturing cost of the resonator increases.

[0006]

[Problems to be solved by the device]

 The present invention was devised in view of the above circumstances, and is capable of reducing intake noise in a wide range of engine revolution speeds, and is inexpensive as a resonator that can be widely applied to engines of various specifications. It is intended to be provided to.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a resonance chamber that is connected to an intake pipe of an engine through a communication pipe having a small diameter.In the communication pipe, an inner pipe slidable in the axial direction of the pipe is installed. A resonator in an intake system characterized in that a variable-length inlet passage connecting the intake pipe and the resonance chamber is formed by sliding the inner pipe in accordance with the engine speed. It is a proposal.

[0008]

【Example】

 Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. (It should be noted that the description of the matters already described with reference to FIG. 1 regarding the conventional resonator will be omitted.) According to the present invention, the resonator 28 is slidable in the communicating tube 22 in the axial direction. An inner tube 26 is inserted so that it can be obtained. Protrusions 30 that extend in the axial direction are provided above and below the outer peripheral portion of the inner pipe 26, and the protrusions 30 are fitted in grooves 32 that are recessed above and below the inner peripheral surface of the communication pipe 22, respectively. 26 can be freely displaced in the axial direction, but is held so as not to rotate about the axis. Further, a nut portion 34 is provided at the end of the inner pipe 26 on the side of the common chamber 24, and a screw shaft 36 is screwed into the nut portion 34. An end portion of the screw shaft 36 on the side far from the nut portion 34 penetrates a lid member 38 of the resonance chamber 24 and projects to the outside, and is connected to a motor shaft of a reversible motor 40. The reversible motor 40 is controlled by a controller 42 that receives a signal related to the engine speed Ne and outputs a drive output.

According to the above configuration, the reversible motor 40 is driven by the drive output supplied from the controller 42 according to the operating state of the engine for a time commanded in either the forward or reverse direction. Rotation of the reversible motor 40 causes the screw shaft 36 to rotate, and the nut portion 34 and the inner tube 26 are displaced in either the left or right direction in FIG. 1 according to the rotation time of the motor. FIG. 1 shows a state in which the inner pipe 26 is substantially completely contained in the small-diameter communication pipe 22, and at this time, the effective length of the inlet passage connecting the lower intake pipe 10 and the resonance chamber 24 is the minimum It is l ₁ . The inner tube 26 in FIG. 1 can be displaced to a position right up shown by a chain line, the effective length of the small diameter of the inlet passage consisting of the time communicating tube 22 and the inner tube 26. The longest l ₂ Therefore, the length of the inlet passage changes between l ₁ and l ₂ depending on the engine speed. As the length l of the inlet passage is increased or decreased, the resonance frequency f is increased or decreased as shown in Formula 1 above, and the intake noise is effectively reduced over a wide rotational speed range in accordance with the operating state of the engine. be able to. Further, since the resonance frequency f can be increased / decreased by increasing / decreasing the length 1 of the inlet passage as described above, it is possible to easily cope with a plurality of types of engines having different specifications, and There is an advantage that the manufacturing cost can be reduced by sharing the above.

In the above embodiment, as the actuator for driving the inner pipe 26 in the axial direction, a screw / nut type actuator composed of the reversible motor 40, the screw shaft 36 and the nut member 34 is exemplified, but of course. Any other actuator such as an air cylinder can be appropriately adopted.

As described above, the resonator in the intake device according to the present invention has a resonance chamber connected to the intake pipe of the engine through a communication pipe having a small diameter. A slidable inner pipe is inserted in the inner pipe, and a variable-length inlet passage connecting the intake pipe and the resonance chamber is formed by sliding the inner pipe according to the engine speed. It is possible to provide at low cost a resonator capable of effectively reducing intake noise over a wide operating range of the engine, which is practically useful.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of the present invention, partially shown in section.

FIG. 2 is an enlarged front view of an inner pipe mounting portion in FIG.

[Explanation of symbols]

 10 Lower intake pipe 22 Communication pipe 24 Resonance chamber 26 Inner pipe 28 Resonator

Claims (1)

Claims for utility model registration: Claim: 1. An engine having a resonance chamber connected to an intake pipe of an engine through a communication pipe having a small diameter, the inner pipe slidable in the pipe axial direction in the communication pipe. And a variable length inlet passage connecting the intake pipe and the resonance chamber is formed by sliding the inner pipe in accordance with the number of revolutions of the engine.