JPH0218260Y2 - - Google Patents

Description

[Detailed explanation of the idea] B Industrial application field The present invention relates to a silencer for internal combustion engines.

B. Prior Art Conventionally, in a muffler for an internal combustion engine, in which a tailpipe for discharging exhaust gas from the muffler is simply protruded outside the muffler, the tailpipe itself generates air column resonance, causing low-frequency noise. There is a problem in that the components cause muffled noise inside the vehicle.

Therefore, a silencer equipped with a resonant silencing element that muted low frequency components without increasing back pressure was developed in 1978.
- Although it is proposed in Publication No. 193007, it has the disadvantage that the exhaust gas hits one end edge on the inlet side of the outlet pipe (tail pipe), disrupting the flow and generating secondary airflow noise. In order to reduce such secondary air flow noise, a problem arises in that a complicated structure is required to connect the inlet pipe from the small diameter part to the large diameter cervical pipe via the widened part.

C. Purpose of the invention In view of the above, the present invention eliminates the air column resonance of the tailpipe itself without increasing back pressure and without generating airflow noise in the engine of the tailpipe, and eliminates low frequency components in the passenger compartment. An object of the present invention is to provide a muffler for an internal combustion engine that eliminates muffled noise.

D. Structure of the Invention In order to achieve the above object, the muffler for an internal combustion engine of the present invention has an exhaust inlet 6a that opens into the high frequency resonance chamber 4 in the muffler, and an exhaust outlet 6b that opens into the low frequency resonance chamber 5. A straight inner tail pipe 6 that penetrates and projects outward from the muffler body 2 and has no small holes in its pipe wall; An outer tail pipe 7 is provided, one end of which is opened to the low frequency resonance chamber 5, and the other end of which is opened to protrude downstream and outward from the exhaust outlet 6b of the inner tail pipe 6. An annular gap is formed between the pipes 6 and 7 to provide a communication path 8 to the low frequency resonance chamber 5, and the exhaust outlet 6b goes around the outlet edge of the inner tail pipe 6 to connect to the communication path 8. It was configured as follows.

E. Example In the example shown in FIG. 1, the tail pipe is formed of a double pipe. In this embodiment, 1 is an exhaust pipe from the engine, 2 is a silencer body, 3 is a partition wall, 4 is a high frequency resonance chamber, 5 is a low frequency resonance chamber, and 6 is a so-called so-called pipe provided through the partition wall 3. It is a straight inner tailpipe and does not have any small holes in its wall as shown. Then, the exhaust inlet 6a opens into the high frequency resonance chamber 4,
The exhaust outlet 6b is fixedly provided so as to penetrate the low frequency resonance chamber 5 and protrude from the vessel body 2 to the outside. Reference numeral 7 denotes an outer tail pipe, which is formed to have a larger diameter than the inner tail pipe 6 and is installed approximately concentrically with the inner tail pipe 6 so as to fit on the outer periphery of the inner tail pipe 6. 6,
A communication path 8 to the low frequency resonance chamber 5 is provided by forming an annular gap between the two. The exhaust outlet 6b goes around the outlet edge of the inner tail pipe 6 and connects to the communication path 8. One end of the outer tail pipe 7 is opened to the low frequency resonance chamber 5, and the other end is opened to protrude downstream and outward from the exhaust outlet 6b of the inner tail pipe 6.

F. Effect Since the exhaust gas introduced into the inner tail pipe 6 passes straight through the straight inner tail pipe 6 and is discharged to the outside, the exhaust resistance at the tail pipe does not become large. Therefore, back pressure is not increased. Further, the air column resonance of the tail pipe itself is eliminated by communicating with the low frequency resonance chamber 5 through the communication passage 8, and muffled noise in the vehicle interior due to low frequency components can be eliminated. Further, since the exhaust gas flowing out from the inner tail pipe 6 does not hit the left end edge of the outer tail pipe 7, the flow is not disturbed and no secondary air flow noise is generated.

G. Effects of the invention As described above, according to the invention, it is possible to remove the muffled sound in the passenger compartment due to low frequency components by excluding the air column resonance of the tail pipe itself without increasing the back pressure, and furthermore, It has the advantage of realizing a muffler with a simple structure that does not generate secondary airflow noise from the edge of the tailpipe.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a muffler section showing an embodiment of the present invention. 1... Exhaust pipe, 2... Silencer body, 3... Partition wall, 4... High frequency resonance chamber, 5... Low frequency resonance chamber, 6... Inner tail pipe, 6a... Exhaust inlet, 6b...Exhaust outlet, 7...Outer tail pipe, 8...Communication passage.

Claims (1)

[Scope of utility model registration request] The exhaust inlet 6a opens into the high frequency resonance chamber 4 in the silencer, and the exhaust outlet 6b penetrates the low frequency resonance chamber 5 and projects outward from the silencer body 2. A straight inner tail pipe 6 with no small holes, and a diameter larger than the inner tail pipe 6, one end of which opens into the low frequency resonance chamber 5, and the other end of which is connected to the exhaust flow of the inner tail pipe 6. Exit 6b
An outer tail pipe 7 is provided which projects outward from the downstream side and is opened, and an annular gap is formed between these double tail pipes 6 and 7 to form a communication path 8 to the low frequency resonance chamber 5. In addition to providing the exhaust outlet 6b
A silencer for an internal combustion engine configured such that the tail pipe extends around the outlet edge of an inner tail pipe 6 and is connected to a communication passage 8.