JPH0668245B2 - Exhaust gas flow accelerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for accelerating an exhaust gas flow and sucking air by a negative pressure generated at that time.

(Prior Art) Gas produced by combustion in an internal combustion engine is released into the atmosphere through an exhaust system pipe. The flow velocity of the exhaust gas flow is 650 to 800 m / sec immediately after it leaves the cylinder, which is a high speed exceeding the speed of sound, but it is immediately attenuated and stabilizes at about 200 m / sec when there is no load.

On the other hand, for example, a gasoline engine for automobiles is provided with a catalyst, a silencer and the like in order to take measures against exhaust gas and noise, whereby the exhaust gas flow is discharged at a reduced flow velocity.

(Technical problem) The exhaust gas flow that is released into the atmosphere due to such load resistance increases back pressure due to the slowing down, lowers the exhaust efficiency, and the exhaust gas temperature also rises. Although the rise in exhaust gas temperature is not remarkable at the time of idling, it is a problem when it is released in large quantities during traveling, and it is a problem because it is high in temperature, which is one of the causes for deteriorating the environment. In addition, even though it is purified by a catalyst, etc., the CO and NOx values at idle when no load is applied are used as a guideline. It significantly increases as the load increases.

The present inventor has been conducting research for many years on the influence of the flow velocity of exhaust gas on the operation of an internal combustion engine. As a result, it was found that a great variety and remarkable effects can be obtained by increasing the flow velocity of the exhaust gas flow, and some of the results have already been filed.

This invention was also made in the course of the above research, and its purpose is to accelerate the flow velocity of the exhaust gas flow, thereby realizing a smooth release of the exhaust gas to the atmosphere and sucking the outside air by the negative pressure generated by the acceleration. However, it is another object of the present invention to provide an exhaust gas flow accelerating device capable of purifying the exhaust gas by colliding and mixing the exhaust gas flow with the exhaust gas flow.

(Technical Means) In order to achieve the above object, the present invention is directed to a disconnection of an exhaust gas flow path flowing in an exhaust system pipe at a rear end portion of a straight tubular pipe line connected to a long exhaust system pipe of an internal combustion engine. At least two stages of accelerating units that reduce the area and accelerate the flow velocity of exhaust gas are installed in the flow direction, and suction ports that suck air from the outside are opened in the expansion chambers of the accelerating units, and outside each accelerating unit. A suction chamber divided by a partition is installed for each accelerating unit, and an expansion space with an enlarged flow cross-sectional area is provided at the rear end of the air suction passage that communicates with the air intake port at one end, and at least the airflow is divided. A front end portion of a diversion pipe line formed in a double cylinder shape is connected to an expansion space, and a rear end portion of each diversion pipe line is connected to each of the divided suction chambers.

It is desirable that the accelerating section can enhance the exhaust gas flow to a high-speed airflow, that is, to a stage at which the sound velocity of the portion is exceeded. For that purpose, it was confirmed by experiments that after accelerating with the throttle tube and the throat, on the contrary, it is necessary to expand the cross-sectional area by a predetermined amount, for example, about 1.7 times the minimum cross-section in order to obtain Mach number 2. .

The expansion chamber is provided for that purpose, but in the present invention, since the negative pressure generated by the high-speed air flow sucks air and introduces it into the expansion chamber, the cross-sectional area is increased by the additional amount of the air. Further, the volume of the accelerating unit in the latter stage is also set to always exceed the volume of the former stage.

Furthermore, it is preferable that the flow dividing pipe for dividing the air into each of the divided suction chambers has the same number of suction chambers as that of the multiple cylinders, and in that case, the front end portion prevents an adverse effect due to generation of a shock wave, In order to secure the amount of each divided air flow, it is advisable to arrange the inner one projecting more forward than the outer one.

(Embodiment) The present invention will be described below with reference to the drawings. In FIG. 1, 1 is an internal combustion engine, 2 is an exhaust system pipe, 3 is a load resistance of the exhaust system pipe, and actually the resistance of the pipeline itself. Also included, but here catalyst 3 ₁
The muffling section 3 ₂ is representative. 4 is an accelerating suction part in which an accelerating part and a suction chamber are integrated, 5 is an air suction path leading to an air intake 6, 7 is a muffler for intake, 8 is a diversion conduit, and 9 is a tail pipe. The exemplified intake air may be heat-exchanged with a water jacket 10 provided for cooling the internal combustion engine 1.

The specific structure of the acceleration suction unit 4 is illustrated in FIG.
It is a two-stage structure having a structure integrated with a sound deadening mechanism. At a drawing, a casing 11 covering the entire silencer unit 3 ₂ and the acceleration suction unit 4 connected downstream thereof, 12 an exhaust system pipe 2
Shows the connection to.

Reference numeral 13 denotes a pre-throttle portion which is arranged in the preceding stage of the muffler and which preliminarily accelerates the exhaust gas flow, 14 denotes a perforated muffler pipe connected to the downstream end of the throttle portion 13, and the muffler pipe 14 serves as the exhaust gas flow. It has a large number of small holes 15 through which The hole diameter of each small hole 15 can be arbitrarily selected and the size can be changed. A space between the outer periphery of the sound deadening pipe 14 and the casing 11 is filled with a filling material 16 that also serves as a heat insulating material and a sound deadening material, with an appropriate density.

The accelerating part of the accelerating suction part 4 is connected to the rear end of the central silencer pipe 14 to reduce the exhaust cross-sectional area of the first throttle pipe 17, and to the rear end of the first throttle pipe 17 to maintain the throttle diameter. And a first accelerating section 20 comprising an expanded first expansion chamber 19, and an expansion chamber 19
It has a second throat 21 connected to the rear end thereof and a second accelerating portion 23 composed of a second expansion chamber 22 connected to the rear end thereof, and is separated from the sound deadening portion by a boundary wall 24. 20, 23
The outer side of the first and second partition walls 25 and 26 are separated from each other.
The suction chambers 27 and 28 are connected to the tail pipe 9 while the expansion chamber 22 behind the second throat 21 is enlarged.
A plurality of suction ports 2 are provided on the tapered walls of the first and second expansion chambers 19 and 22.
9 and 30 are opened, and the airflows of the first and second suction chambers 27 and 28 are sucked into the expansion chamber separately.

The first accelerating section 20 is throttled so that the flow velocity of the exhaust gas flow in the expansion chamber 19 exceeds the speed of sound. Moreover, in the 2nd acceleration part 23,
Since the cross-sectional area is expanded and the outside air is allowed to flow in without resistance, the mixture of exhaust gas and air is released into the atmosphere from the tail pipe 9 while maintaining the high speed obtained in the first accelerating unit 20. be able to. Therefore, the second acceleration unit
The increase rate of the internal volume of 23 was set to be about twice that of the first accelerating section 20, and good results were obtained.

The air suction passage 5 communicates with the first and second suction chambers 27, 28 via the intake silencer 7, and the intake silencer 7 has a perforated silencer pipe 31 at the center and a tapered shape at the front end thereof. It continues to the connecting portion 33 to the air suction passage 6 via the preliminary throttle portion 32, and its rear end portion opens into the expansion space 35 defined by the boundary wall 34. 36 is a small hole of the perforated silencer tube 31, it is formed in the same manner as the muffling section 3 _second small hole 15 described above. 37 is a casing for the same purpose as above 38
The filling material filled between the silencer pipe 31 and the sound deadening pipe 31 is shown.

The diversion conduit 8 connects the expansion space 35 and the two suction chambers 27, 28, and the second diversion conduit 8 _{2 of} small diameter penetrates the center of the first diversion conduit 8 ₁ of large diameter. In the concentric double-tube arrangement, the rear part of the first branch pipe 8 ₁ is connected to the first suction chamber 27, and the rear end of the second branch pipe 8 ₂ is connected to the second suction chamber 28 by connecting pipes 39, respectively. Connected through. Front ends 4 of the first and second branch pipes 8 ₁ and 8 ₂
Although 0 and 41 project into the expansion space 35, the front end portion 40 of the inner first flow dividing pipe 8 ₁ projects slightly more than the other so as to properly divide the flow and generate shock waves. Is intended to ensure that the proportion of the split air quantity is not adversely affected. In addition, 42 is a front cap of the silencer casing 11, 43 is also a rear cap, both of which are integrally assembled by screw portions 44 and 45 formed inside the front and rear ends of the casing, and 46 and 47 are intake silencers. The front and rear caps of the container 7 are similarly assembled by the screw portions 48 and 49 formed inside the front and rear ends of the casing 38. Further, reference numeral 50 indicates a fastening portion by a screw of each portion. Although such a fastening structure is not limited, disassembling enables facilitating inspection and partial correction of abnormality of each part, and repair / replacement of a defective part.

(Operation) When the internal combustion engine is started, the exhaust gas flow discharged at high speed from the exhaust valve passes through a large exhaust system pipe and resistance to weaken the flow force, and reaches the accelerating unit with the flow velocity reduced. However, when the exhaust gas flow reaches the first acceleration unit 20, the first throttle pipe
The velocity gradually increases as it passes through 17, and finally becomes a flow that exceeds the sonic velocity of the place near the throat, and the pressure in the first expansion chamber 19 of the high-speed airflow forms a significantly negative pressure, and the second accelerating portion At 23, the same high speed and high negative pressure are maintained.

As a result, the outside air that has flowed into the first and second expansion chambers 19 and 22 from the air intake port 5 is the first and second flow dividing pipes 8 ₁ and 8 ₂ , the first and second
It is sucked at high speed through the suction chambers 27 and 28 and the respective suction ports 29 and 30, and is discharged into the atmosphere from the tail pipe 9 while being mixed with the exhaust gas flow. In this way, the suction air flow expands in the expansion space 35, and the air is separately guided to the two suction chambers 27 and 28 by the flow dividing pipes 8 ₁ and 8 _{2 from} this, so that the suction air flows interfere with each other. Does not happen. Furthermore, since the inner flow dividing pipe 40 projects forward from the outer flow dividing pipe, the flow can be smoothly divided even if the flow velocity becomes extremely high.

When the exhaust gas flow and the air flow were mixed, the exhaust gas temperature was lowered and the exhaust gas components were purified. This is the expansion chamber 19,
At 22, it is speculated that the exhaust gas flow and the suctioned air flow violently collide with each other at a supersonic speed, and a reaction at the molecular or atomic level occurs not only by mixing gases with each other.
According to the experiment, the exhaust gas temperature decreased to 60% or less as shown in the attached table in the case of a 4-cycle engine with a displacement of 750 cc while passing through the first and second accelerating parts, which were less than 10 cm, and a considerable amount. Water was observed to be produced. This The phenomenon occurs in the case of using the accelerating part where the flow velocity of the exhaust gas flow exceeds the sonic velocity, and this phenomenon was not observed in the non-high-speed airflow below that.

In addition, the air taken in from the air intake 5 is supplied to the air jacket 10
After cooling the engine through the engine, despite the fact that this air jacket is the same as the water jacket of the water-cooled engine, a very satisfactory cooling effect was obtained, and a four-wheel vehicle (displacement 1300cc) was used in the summer. No sign of overheating was found in the actual running test using only the one-stage acceleration section.

(Effect) The present invention is configured and operates as described above,
The back pressure of an internal combustion engine equipped with this device is changed to a low level to improve the exhaust efficiency and purify the exhaust gas discharged from the engine, and at the same time, the exhaust gas temperature is remarkably lowered and instantaneously when passing through the acceleration section. The effect that can be made was exhibited.

The acceleration device of the present invention is provided with at least two stages of accelerating suction portions, and when sucking air by the negative pressure generated therein,
Since the air flow is sucked into each suction chamber separately from each branch pipe, it is possible to remarkably increase the suction air flow, and the mixing of the exhaust gas flow and the air flow proceeds simultaneously in each expansion chamber. Therefore, the mixing processing action is very large, and the desired processing capacity such as purification of exhaust gas or lowering of temperature can be remarkably increased.

[Brief description of drawings]

The drawings show an exhaust gas flow accelerator according to the present invention. FIG. 1 is a conceptual side view showing an example of a state in which the exhaust gas flow is incorporated in an internal combustion engine, and FIG. 2 is a longitudinal sectional view of one embodiment. is there.

Claims (6)

[Claims] Claim: What is claimed is: 1. A cross-sectional area of an exhaust gas flow path flowing in an exhaust system pipe is narrowed at a rear end portion of a straight pipe line connected to a long exhaust system pipe of an internal combustion engine to accelerate an exhaust gas flow velocity. The accelerating unit is installed in at least two stages in the flow direction, a suction port for sucking air from the outside is opened in the expansion chamber of the accelerating unit, and the accelerating chamber is partitioned by a partition for each accelerating unit outside the accelerating unit. Each of which is provided with an expansion space having an enlarged flow cross-sectional area at the rear end of the air suction passage that communicates with the air intake port at one end, and is formed as at least a double-cylinder pipe for dividing the air flow. Is connected to the expansion space, and the rear end of each of the flow dividing pipes is connected to each of the divided suction chambers. 2. The first of the preceding stages among the at least two stages of accelerating parts
The accelerating section is composed of a throttle tube for narrowing the flow passage cross-sectional area, a throat continuing to the rear end of the throat, and an expansion chamber continuing to the rear end of the throat. An exhaust gas flow accelerator according to claim 1, comprising only an expansion chamber continuing to the end. 3. The exhaust gas flow accelerating device according to claim 1, wherein the internal volume of the accelerating section in the subsequent stage is set to always exceed the internal volume of the accelerating section in the preceding stage. 4. The exhaust gas flow accelerator according to claim 1, wherein the accelerating portion has a throat throttled to a stage where the passage speed of the exhaust gas flow exceeds the sonic velocity of the portion. 5. The diversion conduit having a front end formed in a multi-cylinder shape has an arrangement in which the front end of the inner diversion pipe projects forward of the front end of the outer diversion conduit. Exhaust gas flow accelerator as described. 6. The exhaust gas flow accelerating device according to claim 1, wherein the front accelerating section is provided at the most downstream side of the noise reduction mechanism for the exhaust gas flow.