JP2545086B2 - Engine exhaust system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exhaust device for a V-type engine, and more particularly to an exhaust device for enhancing intake and exhaust efficiency by utilizing a pressure wave of exhaust.

(Prior Art) Generally, the length of the exhaust passage is appropriately set so that the exhaust passage near the exhaust valve is at a lower pressure than the intake side at the time of intake / exhaust overlap by using the propagation of the pressure wave of the exhaust. It is known to increase the scavenging effect of the engine. That is, in the V-type engine disclosed in, for example, Japanese Patent Application Laid-Open No. 57-119142, the exhaust passage of the left bank and the exhaust passage of the right bank are connected by the pressure propagation passage, and the exhaust gas is exhausted through the pressure propagation passage. Propagation of the pressure wave is performed.

(Problems to be Solved by the Invention) By the way, when the pressure propagation passage branches off from the middle of the exhaust passage in this way, the angle formed by the exhaust passage and the pressure propagation passage is appropriately set to smooth the pressure wave of the exhaust gas. Propagation needs to be secured. In that case, the setting of this angle must not impair the smooth flow of exhaust in the exhaust passage.

The present invention has been made in view of the above points, and an object of the present invention is to reduce the bend from the exhaust passage corresponding to each bank to the pressure propagation passage in the V-type engine to reduce the pressure wave of the exhaust gas smoothly. This is to ensure that the transmission is performed, and the pressure transmission passage acts as an expansion passage to reduce the exhaust resistance in the exhaust passage as much as possible.

(Means for Solving the Problem) In order to achieve the above-mentioned object, a solution means of the present invention is provided corresponding to each bank, and is provided with an exhaust passage for leading the exhaust gas from the cylinder of each bank to the atmosphere. In the exhaust system of a diesel engine, the pressure that propagates the pressure wave of exhaust gas so that both exhaust passages corresponding to each bank communicate with each other at a predetermined branching portion, and a scavenging effect is obtained by a resonance effect at the time of intake and exhaust overlap of each cylinder. Propagation path is provided. The deflection angle from the exhaust passage upstream of the branch portion to the pressure propagation passage is set to be smaller than the deflection angle from the exhaust passage upstream of the branch portion to the exhaust passage downstream of the branch portion.

(Operation) With the above configuration, in the present invention, the deflection angle from the exhaust passage upstream of the branch portion to the pressure propagation passage is set smaller than the deflection angle from the exhaust passage upstream of the branch portion to the exhaust passage downstream of the branch portion. Therefore, the pressure wave of the exhaust gas smoothly propagates from the exhaust passage to the pressure propagation passage, and the pressure wave propagating in the pressure propagation passage has a resonance effect that makes the vicinity of the exhaust valve a negative pressure when the intake and exhaust gas overlaps in each cylinder. The scavenging effect of the engine can be effectively enhanced.

Further, since this pressure propagation passage acts as an expansion passage, the exhaust resistance in the exhaust passage is reduced as much as possible regardless of the setting of the deflection angle of the exhaust passage in the branch portion.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows a V-6 engine equipped with an exhaust system according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an engine body having left and right banks 2 and 3, and each bank 2.3 of the engine body 1 has three cylinders 4, 4 ...
Is provided. Reference numeral 5 is an intake passage having one end communicating with the atmosphere and the other end branching and opening corresponding to each cylinder 4. The intake passage 5 is formed in a loop between the banks 2 and 3 so as to obtain a supercharging effect by an intake resonance effect due to a pressure wave of intake air between the cylinders 4. Further, 6 and 7 are exhaust passages provided corresponding to the banks 2 and 3, respectively, one end of which is opened to each cylinder 4 of each of the banks 2 and 3 and the other end of which is connected to the atmosphere after being assembled. . The two exhaust passages 6 and 7 are communicated with each other by a pressure propagation passage 8 branched from the middle of the exhaust passages 6 and 7, and the cylinders described above are caused by a pressure wave of exhaust gas propagating through the pressure transmission passage 8. At the time of the intake / exhaust overlap of No. 4, a scavenging effect is obtained by obtaining a resonance effect that makes the vicinity of the exhaust valve relatively low.

Then, in each branch portion 9 from each of the exhaust passages 6 and 7 to the pressure propagation passage 8, the exhaust passage on the upstream side of the branch portion 9
6a, 7a and the pressure propagation passage 8 are connected so as to face each other, and the branch upstream exhaust passages 6a, 7a and the exhaust passages 6b, 7b downstream of the branch 9 form a predetermined angle. Are connected to each other, so that the exhaust passages 6a, 7a on the upstream side of the branch portion are connected.
To the pressure propagation passage 8 is set to be smaller than the deflection angle from the branch upstream exhaust passages 6a, 7a to the branch downstream exhaust passages 6b, 7b.

Therefore, in the above embodiment, both exhaust passages 6, 7
The pressure propagation passages 8 communicate with each other by
Since the pressure wave of the exhaust gas propagating through the exhaust valve causes a resonance effect that causes a negative pressure in the vicinity of the exhaust valve when the intake and exhaust gas overlap, the scavenging effect of the engine can be promoted and the intake and exhaust efficiency can be increased.

Further, in each of the branch portions 9, since the exhaust passages 6a, 7a on the upstream side of the branch portion 9 and the pressure propagating passage 8 are connected so as to face each other, the bending of this connecting portion is reduced and the exhaust gas The pressure wave smoothly propagates from the exhaust passages 6a, 7a on the upstream side of the branch portion to the pressure propagation passage 8, and the scavenging effect of the engine can be effectively enhanced.

Moreover, since this pressure propagation passage 8 acts as an expansion passage, the branch portion upstream side exhaust passages 6a, 7a and the branch portion downstream side exhaust passages 6b, 7b are not connected so as to face each other and form a predetermined angle. Even if connected, the exhaust resistance in the exhaust passages 6 and 7 can be reduced as much as possible.

(Effect of the Invention) As described above, according to the exhaust system for a V-type engine of the present invention, both exhaust passages corresponding to each bank are resonated at a predetermined branching portion at the time of intake and exhaust overlap of each cylinder. A pressure propagating passage communicates with each other to obtain a scavenging effect, and the deflection angle from the exhaust passage upstream of the branch portion to the pressure propagating passage is determined from the deflection angle from the exhaust passage upstream of the branch portion to the exhaust passage downstream of the branch portion. The pressure wave of the exhaust gas is smoothly propagated from the exhaust passage to the pressure propagation passage while reducing the exhaust resistance in the exhaust passage as much as possible by the action of the pressure propagation passage as an expansion passage. The scavenging effect of can be effectively increased.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram showing an embodiment of the present invention. 2,3 …… Bank, 4 …… Cylinder, 6,7 …… Exhaust passage, 8
...... Pressure propagation passage, 9 ...... Branch part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Yuzuru 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. -4646 (JP, Y2)

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. An exhaust system for a V-type engine, which is provided for each bank, and which has an exhaust passage for leading exhaust gas from a cylinder of each bank to the atmosphere. A pressure propagation passage communicating with each other at the branch portion and propagating an exhaust pressure wave so as to obtain a scavenging effect by a resonance effect at the time of intake / exhaust overlap of each cylinder is provided, and from the exhaust passage upstream of the branch portion to the pressure propagation passage. An exhaust system for a V-type engine, wherein a deflection angle is set smaller than a deflection angle from the exhaust passage upstream of the branch portion to the exhaust passage downstream of the branch portion.