JPH0625630Y2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a silencer.

[Prior art]

Conventionally, in a muffler used for an internal combustion engine, as shown in FIG. 4, the rear part of the inlet pipe 100 is branched into two pipes, and the exhaust ports of both branch pipes 101 and 102 are opened to different chambers in the muffler. There is a communication valve in which the switching valve 103 is provided at the branch portion.

[Problems to be solved by the present invention] By the way, in a muffler for an internal combustion engine, at a low engine speed and a low load, it is required to improve the muffling effect rather than the back pressure reducing effect. At high load, it is required to improve the engine output by improving the back pressure reducing effect rather than the muffling effect.

Therefore, in the above-mentioned conventional structure, the switching valve 4
However, when switching from the muffling mode to the low back pressure mode, the exhaust noise suddenly increases, and there is a audible problem in terms of the feeling of riding in the actual vehicle.

Then, this invention aims at proposing the silencer which can eliminate the said problem.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention divides the rear part of the inlet pipe into three parts, and opens the rear end of each branch pipe into a plurality of chambers defined in the container so as to communicate with different chambers. However, a switching valve is provided at the branch portion.

〔Example〕

Next, a first embodiment of the present invention shown in FIGS. 1 and 2 will be described.

1 is a silencer, the outer shell of which is composed of a peripheral wall 1a and front and rear walls 1b, 1c. In addition, the inside of the vessel is divided into 4 by the partition walls 2, 3 and 4.
It is divided into chambers 5, 6, 7, and 8. Reference numeral 9 is an inlet pipe, which is branched into three at the front part of the front wall 1b of the muffler 1. The rear end 10a of the first branch pipe 10 is in open communication with the second chamber 6 in the vessel, and the rear end 11a of the second branch pipe 11 is in open communication with the third chamber 7 in the vessel, and further the third branch. The rear end 12a of the pipe 12 is opened and communicated with the fourth chamber 8 inside the vessel. Reference numeral 13 is a butterfly-type switching valve provided in the pipe of the branch portion, and is adapted to rotate about its supporting shaft 13a to open and close the branch pipes 10, 11 and 12. The switching valve 13 is switch-controlled according to the rotation state of the engine, and is located in the A state at low engine speed and low load, and in the B state at medium speed and medium load. It is positioned in the state C at high rotation and high load. 14a, 14b, 14c are inner pipes that connect the respective chambers. Reference numeral 15 denotes an outlet pipe, the exhaust introduction port 15a of which is in open communication with the fourth chamber 8 inside the vessel, and the rear end 15b is open to the outside of the vessel.

In the present embodiment, when the switching valve 13 is operated to the position A in FIG. 2 when the engine is running at low speed and under low load, exhaust gas from the engine passes through the inlet pipe 9 and the first branch pipe 10 only, It flows into the second chamber 6. Then, a part of the exhaust gas flows through the inner pipe 14a into the first chamber 5 which is the resonance chamber, and the other exhaust gas from the second chamber 6 to the inner pipe 14b, the third chamber 7, the inner pipe 14c and the inner pipe 14c. Fourth
It is discharged to the outside of the device through the outlet pipe 15 through the chamber 8. Therefore, the sound is silenced in all the rooms, and the silencing effect is enhanced.

Further, when the switching valve 13 is switched to the position B in FIG. 2 when the engine is rotating at medium speed and medium load, the exhaust gas from the inlet pipe 9 flows into only the second branch pipe 11. Then, the main flow of the exhaust gas passes through the third chamber 7, the inner pipe 14c and the fourth chamber 8 and flows out of the device through the outlet pipe 15. As a result, the back pressure becomes lower, although the sound deadening effect is less than that described above.

Further, when the switching valve 13 is switched to the position C in FIG. 2 when the engine is rotating at high speed and under high load, the exhaust gas from the inlet pipe 9 is diverted into the three branch pipes 10, 11, 12 and the first branch is performed. Exhaust gas from the pipe 10 and the second branch pipe 11 flows through the above-mentioned path, and the exhaust gas in the third branch pipe 12 flows into the fourth chamber 8 and opens in the fourth chamber 8. It flows out from the outlet pipe 15. Therefore, the outflow path from the third branch pipe 12 is short-circuited and shorter than the outflow path from the first and second branch pipes 10 and 11. Therefore, the muffling effect is reduced, but the back pressure reducing effect is higher than in the low, medium rotation, low, and medium loads.

FIG. 3 shows a second embodiment of the present invention, in which the first branch pipe 10 is branched to a position upstream from the branch portions of the second branch pipe 11 and the third branch pipe 12 in the above embodiment, ，
A switching valve 13 is provided at a branch portion of the third branch pipes 11 and 12. In this embodiment, when the switching valve 13 is operated to the A position in FIG. 3, the exhaust gas from the inlet pipe 9 passes only through the first branch pipe 10, and when it is operated to the B position, the exhaust gas is discharged to the first and second positions. Branch pipe 10,11
When further operated to position C, the exhaust gas flows in through all branch pipes 10, 11 and 12. Therefore, also in this embodiment, the same effect as that of the above embodiment can be exhibited.

[Effect of device]

As described above, according to the present invention, the noise reduction effect can be enhanced at low engine speed and low load, and the back pressure reducing effect can be enhanced at high engine speed and high load. Low rotation, low load to high rotation,
When shifting to a high load state, the sound deadening effect can be temporarily mitigated in the middle rotation and medium load states, so that the exhaust noise suddenly increases and the audibility in the actual vehicle is improved as in the conventional case. You can prevent it from getting worse.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention, FIG. 2 is an enlarged side sectional view of an essential part, and FIG. 3 is a side sectional view of an essential part showing a second embodiment of the present invention. FIG. 4 is a side sectional view showing a conventional structure. 5,6,7,8 …… Room, 9 …… Inlet pipe, 10,1
1, 12 …… Branch pipe, 13 …… Switching valve

Claims (1)

[Scope of utility model registration request] 1. The rear part of the inlet pipe is branched into three,
The rear ends of the respective branch pipes are opened and communicated with different chambers from each other with respect to a plurality of chambers defined inside the vessel, and the branching portion has:
A muffler equipped with a switching valve.