JPS6319537Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in the structure of an on-off valve in an automobile exhaust system.

[Conventional technology]

Automobile exhaust systems generally generate low-frequency muffled noise inside the vehicle when rotating at low speeds, that is, when the temperature of the exhaust gas is low, and generate pipe end jet noise when rotating at high speeds, that is, when the temperature of the exhaust gas is high. do. As is clear from FIG. 8, which shows the relationship between the pipe diameter and the muffled sound, the muffled sound at low frequencies becomes smaller as the diameter of the exhaust pipe is narrowed down. However, as is clear from FIG. 9, which shows the relationship between the pipe diameter and the jet noise, the jet noise actually increases during high-speed rotation. Therefore, it is possible to conversely increase the diameter of the exhaust pipe.The larger the diameter is, the more the jet noise at high speed rotation becomes extremely small, but in this case, the problem arises that low-frequency muffled noise becomes louder. .

In this way, the relationship between low-frequency muffled noise and the generation of jet noise during high-speed rotation is the opposite.
With current technology, it is impossible to eliminate muffled sound and jet noise all at once. However, in order to eliminate the muffled sound, the diameter of the pipe had to be reduced, which inevitably resulted in a large pressure loss during medium and high speed rotation.

Furthermore, even if a catalytic converter is installed in the exhaust system, when the exhaust gas temperature is low due to low engine speed, it takes time for the catalytic converter to warm up (reach activation temperature), and during that time the exhaust gas There was also a drawback that purification was not carried out sufficiently.

Therefore, in order to reduce the muffle noise and the jet noise, for example, Japanese Utility Model Application No. 54-90522 discloses that a large diameter part with a large cross-sectional area of the exhaust gas flow path is installed at the base of the tail tube. A flow path switching system that connects a branch pipe having a small diameter part with a small area, and connects the branch pipe with the base and the large diameter part of the engine when the engine rotates at high speed, and communicates the base and the small diameter part when the engine rotates at low speed. A mechanism is disclosed.

The flow path switching mechanism in this known example is
For example, a valve is fixed to a shaft rotatably supported on a fixed part such as a vehicle body, a link is attached to this shaft, and this link is connected to an accelerator pedal via a steel wire.
The flow path is switched as the accelerator pedal moves.

[Problem that the invention attempts to solve]

However, since this flow path switching mechanism is configured to switch when the accelerator pedal is depressed, a rotating shaft is protruded from the outside of the tail tube, a link is attached to this, and a steel wire is attached to the accelerator pedal. It is necessary to adopt a complicated structure of connection and a mechanism that is difficult to install. In particular, having the rotating shaft protrude from the tail tube may cause abnormal noises when the shaft rotates, and the bearing part and its surroundings, where the shaft rotates, may be easily corroded by rainwater, condensed water, etc. However, there are problems such as the risk of damage due to obstacles on the road surface when driving, parking, or stopping.

Furthermore, since this known example has a branch pipe provided at the end of the tail tube, it could hardly contribute to reducing muffled noise during low speed rotation and jet noise during high speed rotation. However, since the on-off valve is installed almost at the end of the exhaust system, it has not been possible to reduce the pressure loss at the muffler and immediately after it.

Furthermore, Japanese Patent Publication No. 32-9256 discloses a method for driving an on-off valve by attaching a spiral bimetal to the outside of the exhaust pipe and rotating the on-off valve by the expansion and contraction of this spiral bimetal. ing.

However, if the spiral bimetal is installed outside, the exhaust gas temperature cannot be accurately sensed, and the intended switching operation cannot be performed reliably. However, like the flow path switching mechanism described above, since the shaft also protrudes to the outside, it may cause abnormal noise when the shaft rotates, or the shaft may rotate due to rainwater, condensed water, etc. There are problems such as corrosion of the parts and the vicinity thereof.

Incidentally, Japanese Patent Laid-Open No. 54-145813 discloses a system in which an on-off valve is provided between the collecting part of the exhaust manifold and the catalytic converter. This known example is
Since the on-off valve is installed in the middle of the branch pipe,
It was not possible to reduce the jet noise generated at the tube end by opening and closing the tube. Further, the on-off valve in this known example requires a complicated device mechanism outside the exhaust pipe, which not only requires installation space but also has the disadvantage of being expensive.

[Purpose of invention]

The present invention was devised to solve these conventional problems, and the purpose is to provide a structure for an on-off valve in an exhaust system that has a simple structure and mechanism and can be installed inside a branch. be.

[Means for solving problems]

The structure of the on-off valve in the exhaust system according to the present invention is such that the exhaust pipe is branched into two parts, and the on-off valve installed at the branch part also serves as a flow divider plate, and is placed in the central part inside the branch part. It consists of a rotatably pivoted plate and a bimetal or shape memory alloy, one end of which is slidably attached to a slit provided in the plate, and the other end is fixed to the inner central part of the branch. When the exhaust gas temperature is below the set value, the drive unit operates to close one of the branched exhaust pipes with a plate, and when the exhaust gas temperature is above the set value, the drive unit operates to close one of the branched exhaust pipes with a plate. The plate is configured to be driven to stand up approximately at the center of the branch.

[Effect of invention]

In this invention, when the ambient temperature inside the branch is below the set value, the driving part of the on-off valve drives the plate to close one of the branched exhaust pipes, and conversely, the exhaust pipe inside the branch is closed. When the ambient temperature is higher than the set value, the drive section of the on-off valve drives the plate to stand up approximately at the center of the branch, opening both of the branched exhaust pipes.

Therefore, when the engine rotates at low speed, that is, when the exhaust gas temperature is below the set value, the drive section of the on-off valve is activated to close one exhaust pipe with a plate to reduce the pipe diameter, and the engine It applies a load to eliminate low-frequency muffled noise, and quickly raises the temperature inside the exhaust pipe to quickly warm up the catalytic converter and increase catalytic activity.

On the other hand, when the engine is rotating at high speeds, that is, when the exhaust gas temperature is higher than the set value, the drive section of the on-off valve is activated to open the exhaust pipe by raising the plate that was closed during low speed rotations. However, the pipe diameter is doubled and the exhaust gas is divided into two exhaust pipes to reduce jet noise and pressure loss.

[Example of idea]

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 to 4 show an example of an on-off valve in an exhaust system according to the present invention, and in the figures, 1 indicates an exhaust pipe.

This exhaust pipe 1 has two exhaust pipes 2 and 3 on the downstream side.
An opening/closing valve 5 is disposed at the inner center of the branching portion 4, which closes the inlet of one of the branched exhaust pipes 2 when the exhaust gas temperature is low and opens it when the exhaust gas temperature is high.

This on-off valve 5 includes a valve body 6 that also serves as a flow divider plate,
It consists of a drive part 7 for driving this valve body 6, one end of which is rotatably supported in a support groove 11 provided at the center inside the branch part 4, and the other end of which is connected to an exhaust pipe in the branch part 4. It is arranged so that it can rotate to the position of a stopper 10 formed on the wall surface of 2.

The drive section 7 is made of bimetal or shape memory alloy, and has one end fixed to the wall surface of the branch section 4 and the other end slidably attached to the valve body 6 via a slider 9 . This drive part 7 senses the exhaust gas temperature in the branch part 4, and when the exhaust gas temperature is below a set value,
In other words, at the exhaust gas temperature when the engine rotates at low speed,
One of the driven and branched exhaust pipes 2 is closed by the valve body 6, and when the exhaust gas temperature is higher than the set value, that is, when the engine is rotating at high speed, the driven valve body 6 is closed by the valve body 6. It is configured to stand up in the center. A slit 8 is provided in the valve body 6, and a slider 9 at the tip of the drive section 7 is slidably attached to the slit 8, and the valve is opened and closed by contracting and bending the entire drive section 7. There is.

Next, the operation of this embodiment configured in this manner will be explained.

When the engine rotates at low speed, the temperature of the exhaust gas is low, so the atmospheric temperature within the branch section 4 is also low. Therefore, the driving part 7 of the on-off valve 5 closes the exhaust pipe 2 by bending the valve body 6 and bringing the end of the valve body 6 into contact with the stopper 10 as shown in FIG. Only the exhaust pipe 3 is made to flow.

In this way, when the engine rotates at low speed, the on-off valve 5 closes one exhaust pipe 2 and throttles the open pipe system of the entire exhaust system, so when the engine is under load, low-frequency muffled noise is eliminated. Ru.

On the other hand, when the engine rotates at high speed, that is, when the exhaust gas temperature becomes high, as shown in Figure 1,
The drive unit 7 of the on-off valve 5 senses this and positions the valve body 6 of the on-off valve 5 in the middle of the branch part 4 to open the exhaust pipe 2.
is opened, so the exhaust gas flows through the two exhaust pipes 2 and 3.
As a result, the exhaust gas flow rate is reduced and the pipe end jet noise is reduced, and the open pipe diameter of the entire exhaust system is widened, so the pressure loss is also reduced.

In other words, by flowing exhaust gas in parallel through two exhaust pipes with the same diameter, the pressure loss is reduced to 1/4 according to the equation below, which shows the relationship between pressure loss ΔP and exhaust gas flow velocity V, and the pressure loss is extremely low. becomes less.

ΔP=γ/2g×αV ^2If the pipe diameters of the exhaust pipes 2 and 3 are approximately the same, the pipe end jet noise will be approximately 1/2 that of a single exhaust pipe.

Furthermore, since the valve body 6 is located inside the branch portion 4, Karman vortices are less likely to be formed, and the vortex noise caused by the Karman vortices can be reliably eliminated.

According to the present embodiment configured as described above, the valve body 6 is made of a bimetal or a shape memory alloy and is made of a bimetal or a shape memory alloy, and a valve body 6 which also serves as a flow divider plate and is rotatably pivotally attached to the inner central part of the branch part 4. A slider 9 provided at one end is slidably attached to a slit 8 provided in 6,
It has a driving part 7 whose other end is fixed to the inner central part of the branch part 4, and when the exhaust gas temperature is below a set value, the driving part 7 drives and directs one of the branched exhaust pipes 2 to the valve body 6. When the exhaust gas temperature exceeds a set value, the drive section 7 is driven to raise the valve body 6 approximately at the center of the branch section 4. The opening and closing of one of the exhaust pipes 2 is controlled via a drive section 7 that is driven by the atmospheric temperature within the branch section 4, without being operated by an external command based on force or engine speed. can be done.

Therefore, the on-off valve 5 has a simple structure that is simply installed within the branch portion 4, and does not require any complicated operation form.

Therefore, in the part where the on-off valve 5 is provided,
For example, Utility Model Application Publication No. 54-90522 and Special Publication No. 32-
Unlike the conventional system disclosed in Japanese Patent No. 9256, there is no need for the rotation shaft to protrude from the tube. Therefore, this conventional method caused
Abnormal noises caused when the shaft rotates, corrosion of the bearing and its vicinity due to rainwater, condensed water, etc., damage caused by obstacles on the road surface when driving, parking, or stopping, etc. The problem will be resolved.

5 to 7 show various examples of arrangement of the on-off valve 5 which also serves as a flow divider plate.

In the arrangement example shown in FIG. 5, the rear side of an exhaust pipe 1 in which a converter C and a muffler M are arranged from the front side is branched into two to provide two exhaust pipes 2 and 3, and the inner center of the branch part 4 is On-off valve 5 that also serves as a flow divider plate
It has been established.

According to this arrangement example, the on-off valve 5 is the first one mentioned above.
In addition to producing similar effects by operating as shown in Figures 4 to 4, when the engine is running at low speed, the load is applied to the engine, so the temperature of the exhaust gas discharged from the engine rises rapidly. As a result, the catalytic converter C warms up quickly.

In the example arrangement shown in FIG. 6, the rear side of an exhaust pipe 1, which has a converter C disposed on the front side, is branched into two exhaust pipes 2, 3, and mufflers _M1 , _M2 are disposed in the branched exhaust pipes 2, 3, respectively. An opening/closing valve 5 which also serves as a flow divider is provided in the center of the inside of the branched portion 4.

According to this arrangement example, the on-off valve 5 is the converter C
Since the converter C is provided at the rear of the converter C, the warm-up performance of the converter C during low-speed rotation is improved compared to the arrangement example shown in FIG. Furthermore, since the mufflers M ₁ and M ₂ are separately provided in the two branching exhaust pipes 2 and 3, the pressure loss due to the mufflers is reduced compared to the arrangement example shown in FIG. That is, since the flow rate of mufflers M ₁ and M ₂ is always 1/2 of muffler M during high-speed rotation, it is approximately 1/2 of muffler M, as is clear from the above formula for pressure loss ΔP.
become. Furthermore, the noise reduction effect during medium and high speed rotation becomes more reliable.

In the arrangement example shown in FIG. 7, the front side exhaust pipe 1 is branched into two, and two exhaust pipes 2 and 3 are provided.
Converters C ₁ and C ₂ are arranged in exhaust pipes 2 and 3, respectively,
An on-off valve 5 that also serves as a flow divider plate is provided at the center inside the branch part 4, the rear parts of the exhaust pipes 2 and 3 are gathered together to form a common exhaust pipe 1, and a muffler M is arranged in the part of this exhaust pipe 1. This is an example of an exhaust system.

According to this arrangement example, purification of exhaust gas becomes more reliable.

[Effect of idea]

As described above, according to the present invention, the exhaust pipe is branched into two parts, and the on-off valve disposed at the branch part is rotatably pivoted at the center inside the branch part, which also serves as a flow divider plate. a plate body to be attached, and a drive unit made of bimetal or shape memory alloy, one end of which is slidably attached to a slit provided in the plate body, and the other end of which is fixed to the inner central part of the branch part. When the exhaust gas temperature is below a set value, the drive section is driven to close one of the branched exhaust pipes with a plate, and when the exhaust gas temperature is above the set value, the drive section is driven to close one of the branched exhaust pipes with a plate. Since the valve is configured to stand up approximately at the center of the branch, the on-off valve can be placed within the branch, and there is no need to perform special processing on the exhaust pipe or prepare any special accessory equipment. Moreover, interference with other parts and equipment in the exhaust system can be avoided. In addition, the structure is simple, as only the plate and drive unit are required.
It has advantages such as easy installation and assembly work.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a state in which an on-off valve according to an embodiment of the present invention opens two exhaust pipes. FIG. 2 is an enlarged sectional view of the on-off valve in FIG. 1. FIG. 3 is a sectional view showing a state in which an on-off valve according to an embodiment of the present invention closes one exhaust pipe. FIG. 4 is an enlarged sectional view of the on-off valve in FIG. 3. FIG. 5 is a conceptual diagram showing an arrangement example in which the on-off valve shown in FIG. 1 is applied to an exhaust pipe where the rear side of the muffler branches into two. FIG. 6 is a conceptual diagram showing an example of an arrangement in which the on-off valve shown in FIG. 1 is applied to an exhaust pipe in which the rear side of the converter is branched into two parts and a muffler is attached to each part. Figure 7 shows the on-off valve shown in Figure 1 with two converters installed separately.
It is a conceptual diagram which shows the example of arrangement|positioning applied to the exhaust pipe in which the rear side becomes one. FIG. 8 is a diagram showing the relationship between pipe diameter and muffled sound. FIG. 9 is a diagram showing the relationship between pipe diameter and jet noise. Explanation of symbols of main parts, 1, 2, 3...exhaust pipe, 4...branch section, 5...on/off valve, 6...valve body, 7...driver, 8...slit, 9... Slider, 10...Stopper, 11...Support groove, C,
C ₁ , C ₂ ... converter, M, M ₁ , M ₂ ... muffler.

Claims (1)

[Scope of utility model registration request] In an on-off valve that branches an exhaust pipe into two parts and is arranged at the branch part, there is a plate body that also serves as a flow divider plate and is rotatably pivoted to the inner central part of the branch part, and a bimetallic or shaped plate body. It is made of a memory alloy, and has one end slidably attached to a slit provided in the plate body, and a drive part whose other end is fixed to the inner central part of the branch part, and the exhaust gas temperature is below a set value. Then, the drive unit drives to close one of the branched exhaust pipes with a plate, and when the exhaust gas temperature exceeds a set value, the drive unit drives to raise the plate at approximately the center of the branch. A structure of an on-off valve in an exhaust system characterized by being configured as follows.