JPH0281911A - Exhaust noise eliminator - Google Patents

Abstract

PURPOSE:To satisfy both of noise eliminating performance and high output performance by providing a switching means for switching between a passage leading an exhaust gas to an exhaust port through a plurality of muffling chambers and a passage sending the gas straight through a through pipe. CONSTITUTION:In an exhaust noise eliminator 1, a change-over valve 18 for switching between a first passage leading an exhaust gas sent into an exhaust inlet 3 to an exhaust outlet 4 through muffling chambers 8-10 and a second passage sending the exhaust gas straight through a through pipe 13 is provided on the through pipe 13 connecting the exhaust inlet 3 with the exhaust outlet 4. In the low output driving of an engine, the first passage is set as the exhaust pressure is relatively low, and the exhaust gas run into the exhaust inlet 3 is successively passed through the front muffling chamber 8, rear muffling chamber 10 and middle muffling chamber 9 and exhausted from the exhaust outlet 4, during which the noise is sufficiently eliminated. When the output of the engine is increased, the second passage is set in accordance with the increase in exhaust pressure to send the exhaust gas straight through the through pipe 13 to the exhaust outlet 4, so that the exhaust resistance is reduced to improve the output of the engine.

Description

Detailed Description of the Invention A1 Objective of the Invention (+1 Industrial Field of Application) The present invention relates to an exhaust muffler mainly applied to a four-stroke engine of a motorcycle, particularly an exhaust muffler having an exhaust inlet at one end and an exhaust outlet at the other end. The present invention relates to an improvement in an exhaust muffler, in which a plurality of muffler chambers are defined in a muffler box with a plurality of muffler chambers communicating between an exhaust port and an exhaust outlet.

(2) Prior Art In general, exhaust mufflers have the property of increasing exhaust resistance and reducing output performance when the engine is operated at high output.

Therefore, when using a motorcycle that runs on a boat road in a speed race, the normal exhaust pipe equipped with an exhaust muffler is replaced with a racing exhaust pipe to increase the engine's output performance. things are done.

(3) Problems to be Solved by the Invention However, replacing a normal exhaust pipe equipped with an exhaust muffler with a racing exhaust pipe as described above not only complicates the work before and after the race. , two types of exhaust pipes must always be prepared, making transportation and management troublesome.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust muffler that can satisfy both silencing performance and high output performance.

B0 Structure of the Invention (1) Means for Solving the 0 Problems In order to achieve the above object, the present invention provides a through pipe connecting an exhaust inlet and an exhaust outlet in the muffling box, and this through pipe has the following features: A switching means is provided for switching between a first flow path in which the exhaust gas flowing into the exhaust inlet passes through a plurality of silencing chambers and reaches the exhaust outlet, and a second flow path in which the exhaust gas flows straight through the through pipe. It is characterized by

Although it is desirable that the through pipe be formed in a straight line in order to reduce exhaust resistance, it may be gently curved or bent in view of the positional relationship with surrounding equipment without any problem.

(2) Effect In the above configuration, if the first flow path is set by the switching means, the exhaust gas that has flowed into the exhaust port passes through a plurality of mufflers sequentially and is discharged from the exhaust outlet, so the noise is sufficiently muted during that time. be done.

Furthermore, if the second flow path is set by the switching means, the exhaust gas that has flowed into the exhaust inlet will go straight through the through pipe and reach the exhaust outlet, so that the exhaust resistance will be significantly reduced and the output of the engine will be improved.

(3) Examples Embodiments of the present invention will be described below with reference to the drawings.

First, we will start with the first embodiment shown in FIGS. 1 to 3. In Figure 1, 1 is an exhaust silencer for motorcycles,
A cylindrical sound deadening box 2 is provided. This muffler [2 has an exhaust port 3 at the front end and an exhaust outlet 4 at the rear end, and an exhaust pipe 5 extending from a four-cycle engine (not shown) is connected to the exhaust port 3.

Moreover, the inside of the sound deadening box 2 is provided with a pair of front and rear partition plates 67.
It is divided into three chambers: a front silencing chamber 8, an intermediate silencing chamber 9, and a rear silencing chamber 10, and between the front and rear silencing chambers 8° and 10 is a front bulkhead plate 6,
The middle and rear silencing chambers 9 and 10 are communicated via a first communication pipe 11 passing through the rear partition plate 7, and a second communication pipe passing through the rear partition plate 7 communicates between the intermediate and rear silencing chambers 9 and 10.
Communication occurs via a communication pipe 12.

The exhaust pipe 5 is connected with a through pipe 13 that passes through the front partition plate 6.7 and linearly connects the exhaust port 3 and the exhaust outlet 4. This through pipe 13 extends from the exhaust port 3 to the front muffling chamber 8.
The tapered part 14 has a straight pipe part 15 with a rectangular cross section extending from the small diameter end of the tapered part 14 to the exhaust outlet 4. A large number of communicating holes 16, 16, . . . are bored.

Further, a valve hole 17 is bored in the upper wall of the straight pipe section 15, and the inside thereof communicates with the intermediate silencing chamber 9, and a switching valve serves as a switching means for alternately opening and closing the valve hole 17 and the straight pipe section 15. 18 are provided.

This switching valve 18 is attached via a pin 20 to a pair of right and left brackets 119, 19 protruding from the upper surface of the straight pipe section 15, and has a first opening that opens the valve hole 17 and blocks the straight pipe section 15 midway. position (the state shown in Fig. 1) and a second position (the state shown in Fig. 2) which brings the straight pipe portion 15 into a conductive state and closes the valve hole 17. In the first position, the switching valve 18 maintains a posture in which it is pushed toward the second position by the exhaust pressure from the exhaust pipe 5.

Further, as shown in FIG. 3, this switching valve 18 is provided with a weight 21 and a return spring 22 for biasing it toward the first position.

Next, to explain the operation of this embodiment, when the engine (not shown) is operating at low output, the flow rate of exhaust gas discharged from the engine to the exhaust pipe 5 is relatively small, and therefore the exhaust pressure that the switching valve 18 receives on the front side is relatively low. Therefore, the switching valve 18 is held at the first position shown in FIG. 1 by the action of the weight 21 and the return spring 22. That is, the switching valve 18 opens the valve hole 17 and cuts off the straight pipe section 15 midway.

Therefore, the exhaust gas flowing into the exhaust port 3 from the exhaust pipe 5 passes from the tapered portion 14 through the numerous through holes 16, 16... to the front silencing chamber 8, and then passes through the first communication pipe 11 to the rear silencing chamber The chamber lO2 then passes through the second communication pipe 12 and sequentially flows into the intermediate silencing chamber 9. The exhaust gas that has been muffled in this way is
7 through the downstream side of the straight pipe section 15 to reach the exhaust outlet 4,
released into the atmosphere.

When the exhaust flow rate increases as the engine output increases, the switching valve 18 begins to rotate toward the second position due to the exhaust pressure received at the front surface. When the switching valve 18 occupies an intermediate position between the first and second positions, the exhaust gas flowing into the exhaust port 3 reaches the exhaust outlet 4 via the silencing chamber 8°9.10 as described above. The flow is divided into those that advance through the through pipe 13 and reach the exhaust outlet 4, and the output performance is improved by sacrificing the silencing performance according to the ratio of the division.

When the engine enters a predetermined high-output operating state, the switching valve 18 is held in the first position as shown in FIG. Since it is closed, all the exhaust gas that has flowed into the exhaust port 3 passes straight through the through pipe 13 with low flow path resistance, reaches the exhaust outlet 4, and is discharged into the atmosphere. As a result, exhaust resistance is minimized and the output performance of the engine is further improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5.

The straight pipe portion 15 of the through pipe 13 is provided with a valve hole 17 that communicates the inside thereof with the front silencing chamber 8 and a plurality of through holes 16, 16 . . . that communicates the inside thereof with the intermediate silencing chamber 9. .

The switching valve 18 shuts off the straight pipe portion 15 at an intermediate position between the valve hole 17 and the through hole 16, and also has a first surface (fourth surface) that opens the valve hole 17.
It is designed to rotate between the position S) in the figure and a second position where the straight pipe portion 15 is brought into a conductive state and the valve hole 17 is closed.

As shown in FIG. 5, the valve shaft 2 that rotates this switching valve 18
Reference numeral 5 has one end protruding outward from the sound deadening box 2, and a driven pulley 26 and a servo motor 28 are fixed to the protruding end.
A drive pulley 27 fixed to the output shaft of the drive pulley 27 and an operating wire 2
Both ends of the valve 9 are connected so that the switching valve 18 can be rotated by the operation of the servo motor 28. Also, switching valve 1
A return spring 22 is attached to 8 to urge it toward the first position.

The servo motor 28 is installed at a suitable location on the vehicle body or engine (not shown). And on the second day of this servo motor,
A control circuit 3° for controlling its operation is connected, and an engine rotation speed detector 31 is connected to the control circuit 30.

The control circuit 30 operates the servo motor 28 based on the signal sent from the engine rotation speed detector 31 as the rotation speed of the engine (not shown) increases, thereby moving the switching valve 18 to the second position. It is designed to rotate to the side.

The rest of the structure is the same as that of the previous embodiment, and parts corresponding to those of the previous embodiment are given the same reference numerals.

According to this embodiment, when the engine is operating at low speed, the switching valve 18 is held in the first position shown in FIG. 4 by the return spring 22. Therefore, the exhaust gas flowing into the exhaust port 3 from the exhaust pipe 5 passes through the taper portion 14 and the valve hole 17 to the front silencing chamber 8, and then passes through the first communication pipe 11 to the rear silencing chamber 10.
Then, it sequentially flows through the second communication pipe 12 to the intermediate silencing chamber 9. The exhaust air thus muffled is vented through the hole 1616.
... through the straight pipe section 15, reaching the exhaust outlet 4, and being discharged into the atmosphere.

Furthermore, when the engine is in a high-speed operating state, the switching valve 18 is rotated to the second position by the operation of the servo motor, so that the exhaust gas flowing into the exhaust port 3 is directly transferred to the first through pipe 13, that is, the tapered portion 14 and the second position. It travels straight through the straight pipe section 15, reaches the exhaust outlet 4, and is discharged into the atmosphere. Therefore, exhaust resistance is reduced, and the output performance of the engine can be improved.

In addition, when the engine is operating at medium speed, the switching valve 18 is
and the second position, so the exhaust population is 3.
The exhaust gas flowing into the chamber is divided into two parts: one that passes through the silencing chamber 8.10.9 and the other that goes straight through the through pipe 13. As a result, both exhibit intermediate performance in terms of silencing and output. .

C1 Effects of the Invention As described above, according to the present invention, a through pipe connecting an exhaust inlet and an exhaust outlet is provided in the muffling box, and the exhaust gas flowing into the exhaust inlet passes through a plurality of muffling chambers into the through pipe. Since a switching means is provided for switching between the first flow path where the exhaust gas flows straight through the through pipe and the second flow path where the exhaust gas flows straight through the through pipe, the same exhaust muffler can be used by switching the control valve. It is possible to switch between a noise-emphasizing type and an output-emphasizing type, so even if the operating conditions of the engine change, the exhaust muffler can be changed immediately.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional side view of an exhaust silencer for a mortar cycle engine for a motorcycle (shown with emphasis on noise reduction), and FIG. 3 is a perspective view of the vicinity of the control valve in FIG. 1, FIG. 4 is a vertical sectional side view showing the second embodiment of the present invention, and FIG. The figure is a sectional view taken along the line v-V in FIG. 4. 1... Exhaust silencer, 2... Silencer box, 3... Exhaust inlet, 4... Exhaust outlet, 5... Exhaust pipe, 8... Front muffling chamber, 9... Intermediate Sound deadening room, 10... Rear sound deadening room,
13... Penetration pipe, 18... Switching valve as switching means Figure 3 Patent applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] In a sound deadening box with an exhaust inlet at one end and an exhaust outlet at the other end,
In an exhaust muffler that defines a plurality of muffling chambers communicating between an exhaust inlet and an exhaust outlet, a through pipe connecting the exhaust inlet and the exhaust outlet is provided in the muffling box, and the through pipe includes:
A switching means is provided for switching between a first flow path in which the exhaust gas flowing into the exhaust inlet passes through a plurality of silencing chambers and reaches the exhaust outlet, and a second flow path in which the exhaust gas flows straight through the through pipe. An exhaust silencer featuring: