JPH02204616A - Exhaust silencer - Google Patents

Abstract

PURPOSE:To maintain high output of an engine during high speed operation by setting a resonance chamber installed in the vicinity of a downstream side extended chamber and provided with an opening/closing valve, toward an outside space, in a first silencer to which a second silencer is connected on its downstream side. CONSTITUTION:The exhaust silencer of an engine 1 is provided with a first silencer 4 in which an resonance chamber 4a is provided in the vicinity of a downstream side extended chamber 4b, a second silencer 6 connected to the downstream side of the first silencer 4, and an opening/closing valve 9 provided between the first silencer 4 and an outside space. The resonance chamber 4a is operated as an intrinsic resonance chamber by closing the opening/closing valve 9 at the time of low speed operation. On the other hand, the resonance chamber 4a is operated as an extended chamber by opening the opening/closing valve 9 at the time of high speed operation, and a passage leading from the first silencer 4 directly to the outside space is formed. Thereby, it is possible to respond to output enhancement of the engine 1 while maintaining silencer effect to some degree in cooperation with the passages of the silencers 4, 6 arranged in two steps in series.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust silencing device provided in an exhaust system of a vehicle.

When a LIL vehicle is running at low speed, there may be wind noise caused by the movement of the vehicle body, noise from the road surface and tires, etc. ! The running noise caused by friction is low, so only the exhaust sound is particularly loud and feels harsh to the ears.

On the other hand, when driving at high speeds, various noises such as wind noise, running noise, and the intake noise of the engine intake system are loud.
The exhaust sound is also buried in the sound.

Therefore, reducing the exhaust noise as much as possible when driving at low speeds is effective in reducing the overall noise, while reducing the exhaust noise when driving at high speeds is not as effective in reducing the overall noise; Increasing the exhaust resistance in order to reduce exhaust noise is not preferable because it actually hinders the engine from increasing its output.

Therefore, in the past, a two-stage series muffler was used when the engine was running at low speeds, and when the engine was running at high speeds, the exhaust gas could be drawn out from the front-stage muffler via an on-off valve (Utility Model No. 61-1848).
No. 10) has been proposed.

Rotation is illustrated in FIG.

Two exhaust outlet pipes 05°06 behind the first muffler 01
A second muffler 08 is provided in one of the exhaust outlet pipes 05, and an on-off valve 07 is provided in the other exhaust outlet pipe O6.

The first silencer 01 has two partition plates 02a and 02b.
They are divided into resonance chamber 03a, expansion chamber 03b, and expansion chamber 0.
Three chambers 3c are formed, and the exhaust outlet pipe 06 extends from the expansion chamber 03c.

The second muffler 08 also has two partition plates 09a.

Expansion chamber 010a, expansion chamber 010b, resonance chamber 01 in 09b
It is divided into 0C.

When the engine speed is low, the on-off valve 07 is closed, and the first and second mufflers 01 and 08 become a muffling device connected in series, reducing exhaust noise through the muffling effect of resonance and expansion.

In addition, when the engine rotates at high speed, the on-off valve 07 opens and a passage is formed to lead the exhaust gas directly from the first muffler 01, reducing exhaust resistance and connecting the first muffler 01 and the first and second mufflers. The silencing effect of 01.02 also reduces exhaust noise.

However, a resonance chamber attempts to consume the energy of sound waves through resonance, and is effective when you want to eliminate sound at a certain frequency, so it depends on the engine speed. However, even if the same resonance chamber 03a is used, it is not always effective, and it hardly works effectively in a certain frequency range.

The present invention by Ruta was made in view of this point, and its purpose is to use a resonance chamber to effectively muffle exhaust noise with a two-stage muffler during low-speed operation, and to use the resonance chamber to effectively eliminate exhaust noise during high-speed operation. An object of the present invention is to provide an exhaust silencing device which maintains the silencing effect to some extent by replacing it with an expansion chamber, lowers the exhaust resistance, and maintains high output of the engine.

That is, the present invention includes: a first muffler in which a resonance chamber is provided adjacent to a downstream expansion chamber; a second muffler connected downstream of the first muffler; This is an exhaust muffler equipped with an on-off valve provided between a resonance chamber of the muffler and an external space.

By closing the on-off valve provided between the resonance chamber of the first muffler and the external space during low-speed operation, the resonance chamber functions as an original resonance chamber, and the resonance chamber is used to generate exhaust noise mainly in the constant frequency range. By setting the engine to mute the exhaust noise, the two-stage series silencer can more effectively eliminate exhaust noise.

During high-speed operation, by listening to the opening/closing valve, the resonance chamber acts as an expansion chamber, and a passage leading directly from the first muffler to the outside space is formed, which together with the passage of the two silencers in series produces a silencing effect. It is possible to respond to higher engine output by lowering exhaust resistance while maintaining a certain degree of exhaust resistance.

Furthermore, in a vehicle equipped with an engine capable of switching engine output characteristics according to driving conditions, by providing a control means for driving and controlling the on-off valve based on switching of the engine output characteristics, when the engine output characteristics are on the low speed side, The on-off valve is closed to effectively muffle exhaust noise, and when the engine output characteristics are on the high speed side, the on-off valve is opened to reduce exhaust resistance while eliminating exhaust noise.

Furthermore, the control means is provided with a timer for measuring the elapse of a predetermined time from the time when the engine output characteristic is switched from the low output characteristic to the high output characteristic, The on-off valve operates from the open state to the open state when a predetermined period of time has elapsed by the timing means, and conversely, when switching from high output characteristics to low output characteristics, the on-off valve operates from the open state to the open state at the start of the switching. By performing such control, it is possible to suppress the rise in exhaust noise that occurs particularly when the engine output characteristics are switched.

The control means also includes a detection means for detecting when the switching of engine output characteristics is completed, and when switching from low output characteristics to high output characteristics, the control means changes the on-off valve from the closed state to the open state when the switching is completed as detected by the detection means. When switching from high output characteristics to low output characteristics, conversely, the on-off valve may be controlled to operate from the open state to the closed state at the start of the change. It is possible to suppress the rise in exhaust noise.

Support - 1 An embodiment according to the present invention illustrated in FIGS. 2 to 13 will be described below.

FIG. 2 is a configuration diagram of the exhaust system of this embodiment.

Exhaust pipes 3 extending from each cylinder of the engine 1 are collected into one pipe and pass through a catalytic converter 2 on the way to an exhaust introduction pipe 3a.
and is connected to the first muffler 4.

The first muffler 4 is connected to a second muffler 6 via a communication pipe 5, and an exhaust outlet pipe 7 extends from the second muffler 6 and is open to the outside space.

The first muffler 4 is divided into three rooms by two partition plates 10, each including a resonance room 4a and an extension W 4b.

An expansion chamber 4C is formed.

Each room is communicated with each other by a pipe 11.

The exhaust gas introduction pipe 3a passes through the resonance chamber 4a and the expansion chamber 4b and has an outlet in the expansion chamber 4C, and an exhaust gas discharge pipe 8 extends from the resonance chamber 4a, and an on-off valve 9 is provided in the middle thereof. There is.

Further, the second silencer 6 is also partitioned by two partition plates 12 to form three expansion chambers 6a, 6b, and 6c, and each chamber is communicated by a vibrator 13.

The communication pipe 5 connected to the first muffler 4 communicates the expansion chamber 4b of the first muffler 4 with the expansion chamber 6a of the second muffler 6, and the exhaust outlet pipe 7 is expanded. It extends from chamber 6C.

Since the exhaust system of this embodiment is configured as described above,
When the on-off valve 9 is closed, the exhaust gas exhausted from the engine 1 flows through the exhaust pipe 3. It is introduced into the expansion chamber 4C of the first muffler 4 through the exhaust gas introduction pipe 3a, and then guided from the expansion chamber 4b through the communication pipe 5 to the expansion chamber 6a of the second muffler B6, and sequentially expands into the expansion chambers 6b, t3c. It passes through the exhaust outlet pipe 7 and is discharged to the outside.

At this time, the resonance chamber 4a functions as an original resonance chamber and is designed in advance to remove exhaust noise in the low frequency range.

On the other hand, when the on-off valve 9 is open, the exhaust gas outlet pipe 8 is
A passage for exhausting the gas to the outside is formed to reduce exhaust resistance.

At this time, the resonance chamber 4a functions as an expansion chamber! function.

The engine 1 according to this embodiment is an electronic 1111 type fuel injection OOT-+C inline 4-cylinder engine, which has a variable valve timing function that automatically switches valve timing depending on the operating condition, and is suitable for low speed operation. It is equipped with two-stage valve timing for 2 and 2 speeds.

Switching of the valve timing and the 1mrJ1 valve 9
Both drive controls are performed by an electronic control circuit (hereinafter abbreviated as ECtJ) 18, and a diagram of this control system is shown in FIG.

Valve timing is switched by a connection switching mechanism 19 provided in the valve train, as described later.
A valve timing switching signal is input from the E CtJ 18 to the solenoid valve 15 that drives the connection switching mechanism 19 .

The valve timing state is detected by the valve timing detection means 100, and the valve timing detection circuit 11
0 through the valve timing status signal V/T to ECIJ
18 is input.

The ECU 18 outputs a control signal to the valve unit 14 based on the valve timing status signal V/T, and the valve unit 14 drives the on-off valve 9.

E CtJ 18 inputs the engine speed Ne, intake pipe negative pressure Pa, speed V, other shift lever positions, throttle valve opening of the intake passage, oxygen concentration of the exhaust passage, etc. in order to grasp the operating condition. engine speed Ne
Valve timing switching control is performed based on the following.

The valve timing switching control is performed by the above-mentioned control system, and the valve operating mechanism including the connection switching mechanism 19 will be explained below with reference to FIGS. 4 to 7.

This engine has two intake valves and two exhaust valves for each cylinder, and Figure 4 is a perspective view of one of the cylinders with the cylinder block, cylinder head, etc. omitted and the cam transparent. It is.

A combustion chamber 21 is defined between a cylinder head coupled to the upper end of the cylinder block and a piston 20 slidably fitted into the cylinder.

A pair of intake ports 22 and a pair of exhaust ports 23 are provided in the portion forming the ceiling surface of the cylinder head, each intake port 22 is connected to an intake passage 22a, and each exhaust port 23 is connected to a passage ff13b of the exhaust pipe 3. Continuing.

The cylinder head is slidably equipped with a pair of intake valves 24 that can open and close each intake port 22 and a pair of exhaust valves 25 that can open and close each exhaust port 23, and a spark plug 26 is fixed in the center. There is.

Valve springs 27 and 28 are compressed between the cylinder head and flanges 24a and 25a provided at the upper ends of the intake valves 24 and exhaust valves 25 that protrude upward, respectively. Valve 24. The exhaust valve 25 is urged upward, that is, in the valve closing direction.

Such an intake valve 24. Each valve train is provided above the exhaust valve 25, and both have basically the same configuration.The valve train on the intake valve side will be explained below, and the valve train on the exhaust side will be designated by the same reference numerals. It is only shown with .

Referring to FIGS. 5 and 6 together, a camshaft 30 that is rotationally driven from the engine's crankshaft (not shown) at a reduction ratio of 172 has a pair of low-speed cams 31 and 32 and the same pair of low-speed cams. A high-speed cam 33 is integrally formed between the cams 31 and 32.

Further, a rocker shaft 34 is fixedly arranged parallel to the camshaft 30, and the low-speed cams 31, 32, . In contact with the high-speed cam 33, the first
0 Tsuka-arm 35. A 20th lock arm 36 and a free rocker arm 37 are pivotally supported.

This Trotzker arm 35 and the 20th Trotzker arm 36
tappet screws 38 are screwed together to be able to move forward and backward, respectively, and the tappet screws 38 abut on the upper ends of the corresponding intake valves 24, and the tenth lever arms 35. The swinging motion of the 20th lever arm 36 is transmitted to the sliding motion of the intake valve 24.

Furthermore, the free rocker arm 37 is resiliently biased in the direction of sliding contact with the high-speed cam 33 by a lost motion spring 39 interposed between the cylinder heads.

Here, the high-speed cam 33 has a higher cam crest than the low-speed cams 31 and 32, has a wider central angle wi, and has a larger valve lift and valve opening time. This enables valve timing suitable for high-speed operation.

Note that either the valve lift amount or the valve opening time may be changed.

This switching of the valve timing is performed by moving the free rocker arm 37 to the 10th rocker arm 35 and the 20th rocker arm 35 on both sides.
This is done by either swinging freely with respect to the rocker arm 36 or swinging it together with the rocker arm 36. When the rocker arm 36 is rocked freely, the high-speed cam 33 merely swings the free rocker arm 37; The intake valve 24 is driven by the tenth lever arm 35. which is transmitted from the low speed cam 31.32. The low-speed valve timing is caused by the swinging of the 20th lever arm 36.

The other free rocker arm 37 is connected to the tenth lock arm 35.
．． When it is swung together with the 20th lever arm 36,
High-speed cam 33 with large cam crest height and center angle range
The rotation of the tenth lever arm 35. is transmitted to the free rocker arm 37, and the tenth lever arm 35. is integrally connected to the free rocker arm 37. The 20th lever arm 36 is swung exclusively by the high-speed cam 33, and the intake valve 24 is driven at high-speed valve timing.

Therefore, below is the seventh section regarding the valve timing switching mechanism.
This will be explained based on FIGS. 1 to 10.

Figure 7 shows the rocker arm 35°3 with the connection switching mechanism 19.
6, 37 and the rocker shaft 34, each rocker arm 35, 36, 37 is provided with a guide hole of the same diameter parallel to the rocker shaft 34 and equidistant from the rocker shaft 34, A first switching bin 40°, a second switching bin 411, and a disc-shaped regulation bin 42 are slidably fitted into the guide holes, respectively.

In the tenth lever arm 35, a hydraulic chamber 43 is defined between one end of the first switching bin 40 fitted in the guide hole and the closed end of the guide hole, and roughly communicates with the hydraulic chamber 43. A passage 44 is bored, and the passage 44 and the rocker shaft 4
The hydraulic passage 45 formed inside the rocker shaft 34 through the horizontal hole 45a of No. 5 and the hydraulic chamber 43 are always in communication regardless of the swinging state of the tenth lever arm 35.

The second switching pin 41 fitted into the guide hole of the free rocker arm 37 is slidable with one end abutting the first switching pin 40.

In the 20th lock arm 36, a disc-shaped regulation bin 42 is slidably fitted into a bottomed guide hole with the free rocker arm 37 side open, and the regulation bin 42 and the bottom of the guide hole are connected to each other. A return spring 46 is compressed between the sixth bins 4 and 4, which are brought into contact with each other by the spring force of the return spring 46.
0.41.42 is biased toward the hydraulic chamber 43 side.

In addition, a hole 47 is provided at the bottom of the guide hole on which the regulation bottle 42 slides.
A shaft portion 48 coaxially provided with the regulating bottle 42 is inserted into the eye hole 47 .

Since the connection switching mechanism is configured as described above, when the oil pressure in the hydraulic chamber 43 is low, the spring force of the return spring 46 causes the regulation bin 42 to switch between the second switching bin 41 and the second switching bin 41.
sequentially pushes the first switching bin 40 toward the hydraulic chamber 43 side, and
The contact surface between the switching bin 40 and the second switching bin 41 is located between the tenth locking arm 35 and the free rocker arm 31, and the contact surface between the second switching bin 41 and the regulation bin 42 is located at the second switching bin 41.
It is located between the zero lock arm 36 and the free rocker arm 37 and stops, allowing relative rocking between each rocker arm 35, 36, 37, and the connected state is released.

Therefore, in this state, the low speed cams 31 and 32 are in the 10th position.
Tsuka arm 35. The 20th lever arm 36 is swung to drive the intake valve 24, resulting in a low-speed valve timing state.

Further, when the hydraulic pressure in the hydraulic chamber 43 increases through the hydraulic path 452 passage 44, the first switching bin 40 switches to the second switching bin 41, the second switching bin 41 switches to the standard if, and the second switching bin 42, as shown in FIG. is pushed against the return spring 46, and when the guide holes of each rocker arm 35, 36, 37 become coaxial, the first switching pin 40 fits into the guide hole of the free rocker arm 37, and the second switching pin 41 is fitted into the guide hole of the 20th rocker arm 36, and each rocker arm 35° 36, 37
are connected and swing together.

Therefore, in this state, the high speed cam 33 moves the free rocker arm 37 to the tenth lock arm 35. It is caused to swing together with the 20th lever arm 36, and this swing is transmitted to the intake valve 24, resulting in a high-speed valve timing state.

Note that the free rocker arm 37 is provided with recesses 49.49 on the sides facing the first and 20th lever arms 35, 36, respectively, by cutting out the weight for weight reduction. - On the sides of the arms 35, 36 facing the holes 47, spring pins 50, which fit into the holes 47, are press-fitted and fixed.

The spring pin 50 and the hole 47 allow the free date locking arm 37 and the first. The relative swing m between the 20th hook arm 35.3 (3) is regulated, and the contact between the bins 40, 41, and 42 is maintained at all times even in the disconnected state.

This connection switching mechanism includes a detection means 1 for detecting the connection state.
00 is provided.

This detection means 100 includes a shaft portion 48 that is integrated with the regulation bottle 42.
a detection bin 101 disposed coaxially facing the tip of the detection bin 101;
Support member 102 fixed to the side surface of the arm 36
and a spring 103 compressed between the detection bottle 101 and the support member 102 to bias the detection bottle 101 toward the shaft portion 48.
Equipped with.

Furthermore, the end of the detection pin 101 protruding from the support member 102 is provided with a restriction collar 101a that comes into contact with the support member 102 to restrict movement of the detection bottle 101 toward the shaft portion 48. In the disconnected state, the shaft portion 48
When the detection bottle 101 is in the position where it is retracted into the hole 47, the detection bottle 101 does not come into contact with the shaft portion 48, nor does it come into contact with the 20th hook arm 36.

In this detection means 100, the detection bottle 101 is made of a conductive material, and the support member 102 is made of a non-conductive material such as synthetic resin.

On the other hand, at least the regulating pin 42 and the 20th lever arm 36 are made of a conductive material, and the 20th lever arm 36 is made of a conductive material.
is grounded, and the detection bin 101 is connected to the voltage I 104 and serves as an output terminal for the detection signal.

Therefore, the first switching bin 40. Second switching pin 41. When the regulation pin 42 moves and the rocker arms 35, 36, 37 are connected and a high-speed valve timing state is achieved,
When the shaft portion 48 comes into contact with the detection bottle 101 (the state shown in FIG. 7), the output end of the detection means 100 shows a low level voltage.

Conversely, when the rocker arms 35, 36, 37 are disconnected, the shaft portion 48 is separated from the detection bin 101 and the output end of the detection means 100 shows a high level voltage.

Therefore, the detection means 100 can directly detect the valve timing state of the connection switching mechanism, and the detection means 100
When the output terminal is at a low level, it indicates a high-speed valve timing state, and when it is at a high level, it indicates a low-speed valve timing state.

Next, a hydraulic system mechanism for switching the connection switching mechanism will be explained with reference to FIGS. 8 to 10.

The hydraulic chamber 43 in each rocker arm in the valve train of each cylinder is connected to the hydraulic path 4 in each rocker shaft 34 for intake and exhaust through the passage 44 as described above.
5, and the hydraulic passages 45 in the rocker shaft 34 on the intake side and the fJ1 air side are collected into one and connected to the switching valve 60.
It leads to the exit boat 63.

The switching valve 16 is formed in a housing 61 attached to one end surface of the cylinder head, and has an inlet boat 62 below an outlet boat 63, and the inlet boat 62 is connected to an oil pump (not shown).

The housing 61 is provided with a cylinder hole 64 that allows communication between the upper and lower outlet boats 63 and the inlet boats 62 and into which the spool valve body 65 is fitted vertically and slidably.

The spool valve body 65 includes an inlet boat 62 and an outlet boat 6.
An annular four part 66 that can communicate between the two is formed in the upper half, and a similarly shaped annular recess 67 is formed in the lower half, and a cylindrical spring chamber 68 is bored inside with the lower end open. has been done.

The spool valve body 65 is freely fitted into the cylinder hole 64, the spring 69 is housed inside the spring chamber 68, and the lower end of the spring 69 is in contact with the bottom surface of the cylinder hole 64.
The spool valve body G5 is always urged upward.

Note that the space below the spool valve body 65 communicates with the outside so that air can escape.

A hydraulic pressure chamber 70 is formed above the spool valve body 65 between the ceiling surface of the cylinder hole 64 and the hydraulic pressure chamber 70 .
0 is connected to a throttle (not shown) via a passage 71 and reaches an operating valve 74 of the solenoid valve 15 located above via a passage 72.

On the other hand, a passage 75 bored from the center of the cylinder hole 64 also communicates with the operating valve 74 of the solenoid valve 15 (
(See FIGS. 9 and 10), the passage 75 and the passage 72 are brought into communication with each other by the operation of the operating valve 74.

Further, the oil pressure switch 17 for detecting the oil pressure in the outlet boat 63 is attached to the housing G1, and the oil pressure switch 17 can detect whether or not the switching valve 16 is operating normally.

Note that the solenoid valve 15 is connected to the ECU 7 as described above.
The drive is controlled by.

Now, when the solenoid valve 15 is in the OFF state, the operating valve 74 moves between the passages 15 and 72, and the spool valve body 65 is pushed upward by the spring force of the spring 69, as schematically shown in FIG. Therefore, the hydraulic pressure supplied from the input robot 62 is transmitted to the annular recess 61 and the passage 75 on the lower side of the spool valve body 65,
The operating hydraulic chamber 70 above the spool valve body 65
Since no hydraulic pressure is applied to the spool valve body 65, the spool valve body 65 is held in the upper position.

Therefore, the outlet boat 63 is in a closed state, and no hydraulic pressure is applied to the hydraulic path 45 in the rocker shaft 34, thereby maintaining the low-speed valve timing state as described above.

On the other hand, when the solenoid valve 15 is turned on by an instruction signal from the ECU 7, the operating valve 74 opens to communicate the passage 75 and the passage 72, as shown in FIG. the spool valve body 65 is moved downward.

By moving the spool valve body 65 downward, the spool valve body 65
Since the annular recess 66 in the upper half of the valve communicates the inlet boat 62 and the outlet boat 63, the hydraulic pressure of the outlet boat 63 is set to a high pressure, thereby switching the connection switching mechanism to the high-speed valve timing state as described above.

Note that since the inlet boat 62 communicates with the passage 15 through the annular recess 66 of the spool valve body 65, the hydraulic pressure in the hydraulic pressure chamber 70 is maintained at a high pressure through the passage 12, and the spool valve body 65 is also maintained in the downward position. has been done.

As described above, when the solenoid valve 15 is controlled to drive v1 by the instruction signal from the ECU 7, the switching valve 16 is operated to control the oil pressure and switch the valve timing.

This valve timing state can be detected by the detection means 100, and a detection circuit for detecting the valve timing states of all the connection switching mechanisms is shown in FIG.

Since each cylinder is provided with one connection switching mechanism on the intake side and one on the exhaust side, eight connection switching mechanisms are provided for four cylinders, and therefore a total of eight detection means 100 are attached to each connection switching mechanism. be.

In order to detect that all the connection switching mechanisms have completed switching, a valve timing detection circuit 110 shown in FIG. 11 is configured.

Each output terminal of the eight detection means 100 is an ANI) circuit 111.
It is connected to the input terminal of the AND circuit 112 via the NOT circuit 113.

The output end of the 680 circuit 111 shows a high level only when the outputs of all the detection means 100 are at a high level, that is, all the connection switching mechanisms are in the low speed valve timing state, and the output end of the AND circuit 112 shows a high level only when the outputs of all the detection means 100 are in the low speed valve timing state. The output of 100 indicates a low level, that is, a high level only when all coupling switching mechanisms are in a high-speed valve timing state.

This 680 circuit 111. The output of 112 is input to the ECU 18 and is used to control the amount of fuel injection as well as the control valve 9.

In the case of an engine with multiple cylinders, valve timing switching is performed for each cylinder individually, so after a switching signal is sent and one of the cylinders is switched first, the valve timing is changed until switching is completed for all cylinders. During the switching operation, the valve timings of each cylinder are sequentially switched, and the valve timing states are different for each cylinder.

Therefore, during this switching operation, some cylinders are in a low-speed valve timing state and have low exhaust efficiency, while other cylinders are in a high-speed valve timing state and have high exhaust efficiency.

Normally, when the valve timing is not changed, all cylinders are in the same valve timing state and the exhaust efficiency is also equal, and the exhaust pressure of each cylinder with the same pulsation width is generated with a predetermined phase shift from each other, and finally one Since it communicates with the exhaust pipe and exhibits a steady state, the exhaust does not produce particularly loud noise.

However, when changing the valve timing, as mentioned above, the exhaust efficiency differs depending on the cylinder and the pulsation width of the exhaust pressure also differs, so the exhaust pressure is disturbed and sometimes overlaps, resulting in a loud exhaust sound that stands out.

When the valve timing switching of all cylinders is completed, the steady state returns again.

In an engine that has two valve timing states, low speed and high speed, and switches the valve timing based on the engine speed, FIG. 12 shows changes in the sound pressure of the exhaust sound due to engine speed.

Note that the curve in the figure shows the envelope of the sound pressure wave.

When in the low-speed valve timing state A, the sound pressure of the exhaust sound rises at a constant gradient corresponding to the engine speed, and when in the high-speed valve timing state g3C, the sound pressure increases at a higher sound pressure level position as well. The sound pressure of the exhaust sound increases with a certain slope.

At 8 during valve timing switching when the engine speed is between N1 and N2, the sound pressure of the exhaust sound is extremely loud.

In this embodiment, the on-off valve 9 is controlled so as to suppress as much as possible the prominent exhaust noise at the time of switching the valve timing as described above.

That is, the on-off valve 9 is opened and closed based on the engine speed N2, and the on-off valve 9 is always kept closed during valve timing switching to suppress exhaust noise.

The control of this on-off valve 9 is shown in a flowchart in FIG.

First, in step (2), the output level of the AND circuit 111 is determined, and if the level is high, the process jumps to step (2) and the on-off valve 9 is opened.

If the output level of the AND circuit 111 is low level, proceed to the next step (2) to determine the output level of the AND circuit 112, and if it is low level, proceed to step (2) to close the on-off valve 9.
The valve is opened, and if the level is high, proceed to step (3), and the on-off valve 9 is opened.

Since it is controlled as described above, all the connection switching mechanisms 19
When is in low speed valve timing state, step ■,
In route (3), the on-off valve 9 is closed, and the resonance chamber 4a operates as a resonance chamber mainly corresponding to the low frequency region, and the two silencers 4
．． 6, the exhaust sound is resonated and expanded and effectively suppressed.

In addition, when all the connection cutting lines a19 are in the high-speed valve timing state, the open/close valve 9 is opened according to the route of steps ■, ■, and ■, and the exhaust gas passes directly through the first muffler 4. is newly formed to lower the exhaust resistance and cope with the higher output of the engine, and at the same time, the resonance chamber 4
A acts as an expansion chamber and can suppress exhaust noise based on the expansion of the silencers 4 and 6.

During the valve timing switching operation of the connection switching mechanism 19, the on-off valve 9 is opened according to the route of steps (2), (2), and (3), so that the prominent exhaust noise at the time of switching the valve timing is also suppressed.

Therefore, when switching from low-speed valve timing to high-speed valve timing, the on-off valve 9 is maintained in a closed state during the switching operation to suppress the prominent exhaust noise, and when the switching is completely completed (see Fig. 12) Rotation speed N
2) The valve is opened.

Conversely, when switching from high-speed valve timing to low-speed valve timing, the on-off valve 9 changes from open to closed when any one of the connection switching mechanisms 19 is switched (at engine speed N2 in FIG. 12). It can be changed to a valve and can also suppress the protrusion of exhaust noise.

As described above, in this embodiment, during low-speed operation (low-speed valve timing), the on-off valve 9 closes and the resonance chamber 4a effectively acts to effectively reduce exhaust noise.
By suppressing exhaust noise, which is the main noise source during low-speed operation, overall noise can be reduced.

During high-speed operation (during high-speed valve timing), the opening/closing valve 9 opens, and the resonance chamber 4a acts as an expansion chamber to form a passage for exhaust gas to escape directly from the first muffler 4, reducing exhaust resistance. By significantly increasing the flow rate, it is possible to respond to higher engine output.

Further, since the functions of the silencers 4 and 6 are maintained, there is also a noise effect.

By effectively utilizing the resonance chamber in this way, it is possible to reduce the size of an effective muffling device.

Furthermore, by controlling the on-off valve 9 to close during valve timing switching, it is possible to suppress the protrusion of exhaust noise that occurs particularly during valve timing switching.

In the above embodiment, the control of the open m valve 9 was performed based on the output signal of the valve timing detection circuit 110.
E CU 18 is equipped with a timer as a timing means, and when switching from low speed to high speed valve timing, E CL
l Measure the elapse of a predetermined time (sufficient time for all connection switching mechanisms 19 to complete switching) from the transmission of the valve timing switching signal from 1B, and open the on-off valve 9 at that point. You can do it like this.

Note that when switching from high speed to low speed valve timing, the on-off valve 9 is opened when the valve timing switching signal is issued.

By doing so, the on-off valve 9 is always closed during the valve timing switching operation, and it is possible to suppress the protrusion of the exhaust noise that occurs particularly when the valve timing is switched.

Further, in the embodiment described above, the drive of the on-off valve 9 was controlled based on switching the valve timing, but it may also be controlled directly based on the engine rotation speed Ne, and further based on the intake pipe negative pressure P8, etc. It is also conceivable to perform continuous control.

By controlling iti based on the engine rotational speed Ne, etc., it is possible to apply it to an engine that does not have a variable valve timing function.

The present invention provides an on-off valve between the common I@ chamber of the first muffler and the outside space, so that the m valve is closed during low-speed operation to effectively reduce exhaust noise. Can effectively reduce noise.

On the other hand, during high-speed operation, the on-off valve is opened to reduce exhaust resistance.
The exhaust gas flow rate can be significantly increased to accommodate higher engine output, and the resonance chamber has been changed to an expansion chamber, allowing the silencing effect to be maintained.

Further, in a vehicle equipped with an engine having a function of switching the output characteristics according to the driving state, the above effect can be obtained by driving and controlling the opening/closing valve according to the switching of the output characteristics of the engine.

Furthermore, when the engine output characteristics are switched from low output characteristics to high output characteristics, the on-off valve is opened after a predetermined time has elapsed from the time of switching by the timing means, and when the engine output characteristics are switched from high output characteristics to low output characteristics, That cut! ! ! By closing the valve at the start, it is possible to suppress the protrusion of exhaust noise that occurs when switching output characteristics.

In addition, it is equipped with a detection means for detecting when the switching of engine output characteristics is completed, and when the engine output characteristics are switched from low output characteristics to high output characteristics, the on-off valve is opened when the switching is completed as detected by the detection means, and the high output When switching from the characteristic to the low output characteristic, by closing the on-off valve at the start of the change, it is possible to suppress the protrusion of the exhaust noise that occurs when the output characteristic is changed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional silencing device, Fig. 2 is a block diagram of an exhaust system according to an embodiment of the present invention, Fig. 3 is a block diagram of a control system of this embodiment, and Fig. 4 is a block diagram of an exhaust system according to an embodiment of the present invention. A partially omitted perspective view of the cylinder, FIG. 5 is a perspective view of the first valve train, and FIG. 6 is a sectional view of the same.
Figure 7 is a sectional view showing the connection switching mechanism, Figure 8 is a partially sectional side view of the hydraulic system mechanism that switches valve timing, and Figure 9 is the hydraulic system with the solenoid valve open. A schematic diagram of the mechanism. Figure 10 is a schematic diagram of the hydraulic system mechanism when the solenoid valve is open. Figure 11 is a diagram showing the valve timing state detection circuit. Figure 12 is a diagram showing the exhaust noise versus engine speed. FIG. 13, which is a diagram showing changes in sound pressure, is a flowchart 1 showing control of the on-off valve. 1...Engine, 2...Catalyzer, 3...
Exhaust pipe, 4... first muffler, 5... communicating pipe, 6...
...Second silencer, 7...Exhaust outlet pipe, 8...Exhaust outlet pipe, 9...Opening/opening valve, 10...Partition plate, 11...
・Vibe, 12... Partition plate, 13... Pipe, 14
... Valve unit, 15... Solenoid valve,
16...Switching valve, 17...Oil pressure switch, 18...
・E CLl, 19...concatenation 'J) exchange am, 20
...Piston, 21...Combustion chamber, 22...Intake port, 23...Exhaust port, 24...Intake valve, 25...Exhaust valve, 26...Spark plug, 27.28 ...Valve spring, 30...Camshaft, 31.32...Low speed cam, 33...High speed cam, 34...Rocker shaft, 35...10th lever arm, 36... ...20th rocker arm, 37...Free rocker arm, 38...
- Tappet screw, 39... Lost motion spring, 40... First switching pin, 41... Second switching pin, 42... Regulation pin, 43... Hydraulic chamber, 44...
Passage, 45... Hydraulic path, 46... Return spring, 47.
...hole, 48...shaft, 49...recess, 50...
Spring pin, 61... Housing, 62... Inlet boat, 63... Outlet boat, 64... Cylinder hole, 65... Spool valve body, 66° 67... Annular recess, 68...・Spring chamber, 69... Spring, 70... Operating hydraulic chamber, 71.72... Passage, 74... Operating valve,
75... Passageway, 100... Detection means, 101...
Detection pin, 102... Support member, 103... Spring,
104... Power supply, 110... Valve timing detection circuit, 111. 112...AND circuit, 113...
・NOT circuit.

Claims (1)

[Scope of Claims] 1. A first muffler in which a resonance chamber is provided adjacent to the downstream expansion chamber; a second muffler connected to the downstream side of the first muffler; A silencer comprising an on-off valve provided between a resonance chamber of a first silencer and an external space. 2. A vehicle equipped with an engine having a function of switching output characteristics according to driving conditions, further comprising a control means for driving and controlling the opening/closing valve based on switching of the output characteristics of the engine. Exhaust silencer. 3. A clock means is provided for timing the elapse of a predetermined time from the time of switching the engine output characteristic from the low output characteristic to the high output characteristic, and the control means is configured to: The on-off valve is operated from the closed state to the open state when a predetermined time by the timer has elapsed, and conversely, when switching from high output characteristics to low output characteristics, the on-off valve is activated from the open state to the closed state at the start of the switching. 3. The exhaust silencer according to claim 2, wherein the exhaust silencer is controlled to 4. A detection means for detecting when the switching of engine output characteristics is completed, and the control means controls the on-off valve from the closed state to the open state when the switching is completed as detected by the detection means when switching from low output characteristics to high output characteristics. 3. The exhaust silencing device according to claim 2, wherein when switching from a high output characteristic to a low output characteristic, the on-off valve is controlled to operate from an open state to a closed state at the start of the switching. .