JPH0673329U - Vertical exhaust pipe lid structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a lid structure of a simple structure that significantly reduces exhaust noise emitted from the opening of a vertical exhaust pipe. [Structure] Disc member 2 for closing opening 9 of exhaust pipe 8
The lid 1 including the spherical portion 3 formed on the lower surface and the hinge 4 fixed to the outer peripheral edge of the spherical portion 3 is pin-coupled to the bracket 5 fixed to the outer periphery of the exhaust pipe 8 through the support pin 6. The lid 1 is formed so that it is opened to a position where the stopper 7 comes into contact with the outer circumference of the exhaust pipe by the gas pressure of the exhaust gas and falls in the closing direction by its own weight. Due to the spherical surface portion 3, the reflected sound waves are dispersed and mutually interfere with each other, and the noise can be greatly reduced. [Effect] Overall noise can be reduced. Further, by specifying the opening direction of the lid, noise in that direction can be particularly reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lid structure for a vertical exhaust pipe that is connected to an engine and has its opening facing upward, and more particularly to a vertical exhaust pipe lid structure that is suitable for reducing exhaust noise when the lid is opened.

[0002]

[Prior art]

 As shown in FIG. 7, an exhaust pipe 8 of an engine 12 mounted on a vehicle 11 is of a vertical type that discharges exhaust gas with an opening 9 directed upward. In the case of this exhaust pipe 8, a lid 1a is arranged to open and close the opening 9 to prevent rainwater and the like from entering through the opening 9. While the engine 12 is operating, the lid 1a is released by the gas pressure of the exhaust gas, but since the exhaust gas is at a high temperature, even if rainwater enters the exhaust pipe 8, it vaporizes and does not affect the engine side. On the other hand, when the engine 12 does not operate, the lid 1a falls in the closing direction by its own weight and closes the opening 9 to prevent rainwater from entering. As shown in FIG. 8, the conventional lid 1a is composed of a flat disc member 2a having one end hinged to the vicinity of the opening 9 of the exhaust pipe 8 and is opened to an angle θ at which it can fall by its own weight when opened. The one with the structure is adopted. The angle θ is set to about 65 °, for example. On the other hand, Japanese Utility Model Laid-Open No. 52-170120 is known as a known technique in which an opening / closing device is provided at the exhaust port of a vertical type exhaust pipe. This "opening / closing device of the exhaust port in an internal combustion machine" is provided with a cover that can be opened and closed at the exhaust port of the exhaust pipe protruding like a chimney, and a solenoid rod is connected to the cover via a link mechanism to stop the engine. Sometimes, the cover is closed by energizing solenoid, and the cover is opened by the pressure of exhaust gas to discharge the exhaust gas to the atmosphere side while the engine is operating. This has the effect of preventing the entry of rainwater and the like when the engine is stopped.

[0003]

[Problems to be solved by the device]

 When the lid 1a is not present, the exhaust gas escapes in the vertical direction, so the exhaust noise around the vehicle is low, but in the case of the lid 1a which opens at an angle θ, the exhaust gas flow sound wave is generated as shown in FIG. The noise is reflected by the lid 1a, and the noise in the lateral direction of the vehicle becomes high, for example. That is, in FIG. 8, the airflow sound waves are not propagated to the A position hidden by the shadow of the lid 1a, but the reflected airflow sound waves are propagated to the B position on the open side to become noise. Therefore, in consideration of the arrangement of the lid 1a, it is necessary to set the direction of the position A to the direction that requires noise reduction, but it is not possible to reduce the overall noise. On the other hand, in the opening / closing device disclosed in Japanese Utility Model Laid-Open No. 52-170120, as shown in FIG. 2, the cover 4 is opened by 90 ° or more when it is opened. There is no. Therefore, although the exhaust noise around the vehicle is low, the solenoid, its switching circuit, and the link mechanism are required as described above, the structure of the device is complicated, and maintenance of them is required, and the durability is also low. There is a point.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a lid structure for a vertical exhaust pipe having a simple structure capable of significantly reducing the overall noise on the opening side of the lid. To do.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a lid structure which is provided at an opening of an exhaust pipe which rises vertically, and which is opened by exhaust gas pressure and held at an appropriate opening angle so as to be closed by its own weight. , Which constitutes a lid structure for a vertical exhaust pipe with a curved portion formed on the lower side. Furthermore, by opening and closing the lid along the lateral direction of the vehicle, a large noise reduction in the lateral direction can be achieved. It features a vertical exhaust pipe lid structure designed to reduce overall noise.

[0006]

[Action]

 The lid has a curved portion on the lower side thereof. With the lid open by the angle θ, the air flow sound waves of exhaust gas come into contact with the curved surface and are reflected, but the reflected sound waves travel in different directions and interfere with each other and are attenuated. Therefore, exhaust noise is reduced at all locations on the open side of the lid. Of course, the exhaust noise is low in the shadow of the lid. As a result, overall noise can be reduced.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a plan view of the lid of the present embodiment, FIG. 2 is a side view of FIG. 1, FIG. 3 is a side view of the lid of the present embodiment opened by an angle θ, and FIG. 4 is a plan view of FIG. FIG. 5 is a side view for explaining the reflected sound wave of the exhaust gas of this embodiment, and FIG. 6 is a diagram comparing the noise of this embodiment with the noise of the prior art.

First, the lid 1 of this embodiment will be described with reference to FIGS. 1 and 2. In this embodiment, a case where a spherical surface is used as the curved surface shape portion will be described. The lid 1 includes a disc member 2, a spherical portion 3 integrally formed below the disc member 2, and a hinge 4 fixed to the outer peripheral edge of the disc member 2. The disc member 2 has an area that closes the opening 9 of the exhaust pipe 8, and the spherical portion 3 has a shape obtained by cutting a part of a spherical surface having a radius of curvature R. It is formed of a size that can be loosely inserted into the opening 9. A bracket 5 is fixed to the outer circumference of the exhaust pipe 8, and the bracket 5 and the hinge 4 are pin-joined via a support pin 6. A stopper 7 is formed on the hinge 4 to regulate the open position of the lid 1. In this embodiment, a radius of curvature R of 100 mm to 200 mm is adopted as an example.

3 and 4 show the lid 1 in an open state. The lid 1 can be opened until the stopper 7 of the hinge 4 comes into contact with the outer circumference of the exhaust pipe 8, and the opening angle is indicated by an angle θ. In this embodiment, the angle θ is about 65 °. The angle θ corresponds to the angle at which the lid 1 that has been opened to the state shown in FIGS. 3 and 4 can drop in the closing direction by its own weight when the influence of the exhaust gas pressure disappears, and is limited to 65 °. is not. As shown in FIGS. 3 and 4, the portion of the lid 1 hidden in the shadow corresponds to the position A, and the open side corresponds to the position B. More specifically, in FIG. 4, between the center O of the exhaust pipe 8 and the tangent line OC and OD connecting the outer peripheral edge of the lid 1 corresponds to the A position, and the other portions correspond to the B position.

Next, the operation of this embodiment will be described. When the engine is operating, the lid 1 is opened by an angle θ as shown in FIGS. 3, 4 and 5 due to the gas pressure of the exhaust gas. As shown in FIG. 5, the airflow sound waves 10a, 10b, 10c, etc. of the exhaust gas hit the spherical surface of the spherical surface portion 3 of the lid 1 and become reflected sound waves 11a, 11b, 11c, etc. As shown in the figure, the reflected sound waves 11a, 11b, 11c, etc. are reflected in each direction depending on the contact position with the spherical surface. That is, the light is dispersed in a certain direction without being reflected. The reflected sound waves 11a, 11b, 11c and the like interfere with each other. Due to this interference and dispersion effect, the reflected sound wave is attenuated and the noise at position B is reduced.

FIG. 6 shows the noise reduction effect of this embodiment, where the horizontal axis represents frequency [Hz] and the vertical axis represents noise [dB]. The solid line indicates the measured value in the central axis direction of the inner surface of the opened lid 1, and the measured value in the tangential line OC and OD directions. The dotted line indicates the measured value of noise at the same position when the lid 1 of the conventional technique shown in FIG. 8 is adopted. In the frequency range shown by E, there is almost no difference between the present embodiment and the prior art, and the diagram is omitted. As is clear from the figure, it can be seen that in both of these cases, the noise is lower, and in particular, a large noise reduction effect can be obtained.

As described above, since noise is originally low at the position A hidden in the shadow of the lid 1, if the direction is aligned with the lateral direction of the vehicle, the lateral noise of the vehicle becomes particularly low. Of course, the B position also has low noise by adopting this embodiment. If the opening direction of the lid 1 of the exhaust pipes 8, 8 arranged on the left and right of the vehicle is arranged laterally and the noise in the lateral direction is particularly reduced, the noise at position B of the exhaust pipe 8 on the left side is transmitted to the right side, The noise at position B on the right is transmitted to the left. However, generally, the sound source emitted from the cylindrical end face such as the opening 9 of the exhaust pipe 8 becomes a point sound source and is attenuated in proportion to the distance. Therefore, the noise is considerably attenuated while traveling the distance corresponding to the vehicle width, and the noise at the B position on the opposite side has almost no effect. As described above, by setting the opening direction of the lid 1 to the lateral direction of the vehicle, the most disturbing lateral noise can be reduced.

In the above embodiments, the lid 1 has the lower surface with the spherical portion 3 formed, but may have a curved surface. Further, the opening direction of the lid 1 does not have to be arranged in the lateral direction of the vehicle, but may be arranged in accordance with the direction in which noise reduction is most needed. Further, the angle θ and the radius of curvature of the spherical portion 3 are not limited to the values in the embodiment. Further, the curved surface-shaped portion such as the spherical surface portion 1 may be formed integrally with the disc member 2 or may be a separate member fixed thereto.

[0014]

[Effect of device]

 According to the present invention, the following remarkable effects are obtained. (1) By providing a lid with a curved surface portion provided at the bottom at the opening of the exhaust pipe, the reflected sound waves of the exhaust gas disperse and interfere with each other, and noise can be greatly reduced. (2) By specifying the opening direction of the lid, the noise in that direction can be particularly reduced, and the reduction of the overall noise eliminates the influence of the noise of the left and right sides of the vehicle, reducing the overall noise around the vehicle. Can be done. (3) Since the lid falls by its own weight, it has a simple structure and can be implemented at low cost. (4) By forming the curved portion from a separate body, it can be applied to the existing exhaust pipe lid.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a side view showing a state in which the lid of this embodiment is opened to an opening position at an angle θ.

FIG. 4 is a plan view of FIG.

FIG. 5 is an explanatory side view showing a dispersed state of reflected sound waves of the present embodiment.

FIG. 6 is a diagram showing the noise reduction effect of this embodiment.

FIG. 7 is a side view showing an outline of a mounting structure of a vertical exhaust pipe arranged in a vehicle.

FIG. 8 is a side view showing a conventional exhaust pipe lid structure.

[Explanation of symbols]

 1 Lid 2 Disc Member 3 Spherical Part 4 Hinge 5 Bracket 6 Support Pin 7 Stopper 8 Exhaust Pipe 9 Opening

Claims (2)

[Scope of utility model registration request] 1. A lid structure which is provided in an opening portion of an exhaust pipe which rises vertically, is opened by exhaust gas pressure, and is held at an appropriate opening angle so as to be closed by its own weight. A vertical exhaust pipe lid structure characterized by being formed. 2. The lid structure for a vertical exhaust pipe according to claim 1, wherein the opening / closing direction of the lid is along the lateral direction of the vehicle.