JP2552478B2 - V-type 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 a scavenging action by utilizing a resonance phenomenon of exhaust gas.

[Prior art]

Conventionally, in an engine exhaust system, various technologies have been proposed in which the resonance vibration of exhaust gas caused by exhaust pulsation is utilized to enhance the scavenging action.

For example, in Japanese Utility Model Laid-Open No. 59-73535, cylinders of an in-line engine are divided into a plurality of cylinder groups, an exhaust manifold is provided for each cylinder group, and a resonance pipe is connected to each exhaust manifold. Communication with at least one communication pipe,
An exhaust device is described in which an opening / closing valve is provided in each communication pipe, and the opening / closing valve is controlled based on the engine speed and load.

On the other hand, in the case of a normal exhaust system for a V-type engine, an exhaust manifold is provided for each bank, and the exhaust passage is extended downward from approximately the central portion of both exhaust manifolds in order to maximize the passage length of the exhaust passage and prevent exhaust interference. Is generally extended to join both exhaust passages below the engine and connect them to the main exhaust passage.

[Problems to be solved by the invention]

In the case of an in-line engine, since the exhaust manifold is arranged on one side of the engine, it can be configured like the exhaust device of the above publication.

However, in the case of the V-type engine, since the intake manifold is arranged between both banks and the exhaust manifold is arranged outside each bank, the resonance tubes connected to both exhaust manifolds are arranged close to each other. It has been considered difficult to apply the technique of the above publication because not only is it impossible to provide a communication pipe, but it is also difficult to dispose a communication pipe in terms of the outer shape and space of the engine.

On the other hand, Japanese Utility Model Laid-Open No. 60-19729 discloses an exhaust system in which the exhaust passages of the exhaust manifolds of the left and right banks of a V-type engine are joined to the combined exhaust passages, and a communication passage is provided to connect the exhaust manifolds of both banks. Has been done.

However, in this exhaust system, the structure of both sides of the engine is unknown, and there is no idea to lay out compactly in the engine room, and further improvement is necessary to lay out compactly in the engine room. Therefore, it is difficult to secure performance while achieving a compact layout.

[Means for solving problems]

In the exhaust system for a V-type engine according to the present invention, a mission case is connected to one end of the V-type engine, an exhaust manifold connected to an exhaust port is provided for each bank, and the exhaust passages of both exhaust manifolds are joined. Is connected to the combined exhaust passage, and a communication passage that communicates the exhaust manifolds of both banks is provided laterally to the ends of both banks and above the mission case.

If necessary, the confluence part of the exhaust passages of both exhaust manifolds is arranged below the engine, and the exhaust passages extending from both exhaust manifolds to the confluence part are formed to have the same length. An on-off valve that opens in the rotation range may be provided.

[Action]

In the exhaust system for the V-type engine according to the present invention, the communication passage that connects the exhaust manifolds of both banks is provided, and the communication passage is disposed on the lateral side of the end portions of both banks. Are communicated with each other through a communication passage shorter than the exhaust passage.

Therefore, the exhaust gas alternately discharged from the cylinders of the left and right banks in the high rotation range resonates in the communication passage, and the positive pressure wave of the exhaust gas from the cylinder in the exhaust stroke becomes an inverted negative pressure wave due to the resonance action. The reverse negative pressure wave propagates to the exhaust port at the end of the exhaust stroke of the cylinder to promote the scavenging action.

When the exhaust passages of both the exhaust manifolds are joined under the engine and the exhaust passages are formed to have the same length, and an opening / closing valve that opens in the high rotation range is provided in the communication passage, the above-mentioned operation is performed in the high rotation range. As described above, the scavenging action is promoted by the exhaust resonance through the communication passage, and the scavenging action is promoted by the exhaust resonance through the exhaust passage in the middle rotation range.

〔The invention's effect〕

According to the exhaust system for a V-type engine of the present invention, as described above, a simple structure is provided in which a communication passage is provided by utilizing the dead spaces on the sides of both banks of the V-type engine and above the mission case. Thus, the exhaust resonance can be utilized to promote the scavenging action in the high rotation range, reduce pumping loss, reduce fuel consumption rate, and improve output.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, a V-type 6-cylinder engine E
Above the crankcase of the left and right sides with an opening angle of about 60 °
A pair of banks 1A and 1B are provided, and three cylinders 3 are formed in the cylinder block 2 of each bank 1A and 1B.
-The 1B cylinders 3 are arranged alternately in the crankshaft direction.

An intake surge tank 4 is installed between both banks 1A and 1B, and the surge tank 4 is a cylinder 3 of the left and right banks 1A and 1B.
Each of the intake ports 5 is connected with a branch intake pipe 5a, an intake pipe 6 extending from an air cleaner is connected to the surge tank 4, and an injector 7 for injecting fuel into the intake port is attached to each branch intake pipe 5a. ing. In the figure, reference numeral 8 is a mission case, and 9 is a distributor.

Exhaust manifold 10 near the outside of each bank 1A / 1B
A and 10B are provided, and the exhaust port 11 of the cylinder 3 of each bank 1A and 1B is the branch exhaust pipe of the corresponding exhaust manifold 10A and 10B.
Connected to 12.

An exhaust pipe 13a extends downward from a substantially central portion in the crankshaft direction of the exhaust manifold 10A of the left bank 1A, is curved in an L shape, and extends to a position in the widthwise center of the lower portion of the engine E, which is slightly rightward.

The exhaust pipe 13b extends downward from a substantially central portion in the crankshaft direction of the exhaust manifold 10B of the right van 1B, and is bent in a V shape on the way to reach the lower side of the engine E.
A merging exhaust pipe 15 extends from the merging portion 14. Then, the passage length of the exhaust pipe 13a from the exhaust manifold 10A to the confluence section 14 and the confluence section 14 from the exhaust manifold 10B.
Further, it is formed to have the same length as the passage length of the exhaust pipe 13b.

A communication pipe 16 that connects the front end of the merging pipe 12a of the exhaust manifold 10A and the front end of the merging pipe 12a of the exhaust manifold 10B is provided in front of the front end of both banks 1A and 1B.

Since the communication pipe 16 is disposed by utilizing the dead space above the mating surface of the transmission case 8 and the cylinder block 2, the central portion of about 1/3 length thereof is horizontally above the mating surface. The left side approximately 1/3 part is inclined to the left downward and is curved backward to be connected to the confluent pipe 12a of the exhaust manifold 10A, and the right side approximately 1/3 part is inclined to the right downward and rearward. It is curved and is connected to the merging pipe 12a of the exhaust manifold 10B. This communication pipe 16 is for promoting scavenging by exhaust resonance in a high rotation range as described later, and in the center portion of the communication pipe 16 in the left-right direction for promoting exhaust resonance, that is, inversion of the exhaust gas positive pressure wave is ensured. A large-diameter volume part 16a is provided for this purpose, and an opening / closing valve 17 for opening and closing the communication passage 16 is provided in the center part of the volume part 16a.
The opening / closing valve 17 is opened / closed by a solenoid type actuator 18 or a negative pressure type actuator controlled by a control unit, and the opening / closing valve 17 is, for example, 5000 rpm or more when operating in a high rotation range where exhaust resistance increases. The valve is opened at the rotation speed and closed at the low rotation speed range.

The passage length from the end of the communication pipe 16 to the volume 16a is
After the exhaust valve of the exhaust cylinder 3 is opened in the high rotational speed range, the positive pressure wave of the exhaust pulsation is inverted in the volume portion 16a and the inverted negative pressure wave is propagated to the exhaust port 11 at the end of the exhaust stroke of the cylinder 3. It is set to such a length. The passage length from the exhaust manifolds 10A and 10B to the merging portion 14 is the above-mentioned communication passage.
It is set to a sufficient length of about 1.5 to 2.0 times half the length of 16.

However, the opening / closing valve 17 may be omitted for the purpose of only promoting the scavenging action in the high rotation range,
The on-off valve 17 may be omitted and the large-diameter volume section 16a may be omitted.

Next, the operation of the exhaust system for the V-type engine will be described.

When the engine is in the low / medium speed range (for example, about 3000 rpm or less), the on-off valve 17 is closed, and the exhaust gas discharged from the left and right exhaust manifolds 10A and 10B via the exhaust pipes 13a and 13b joins. It merges in the section 14 and is discharged to the merged exhaust pipe 15. In this case, since the passage lengths of the exhaust pipes 13a and 13b are set to be relatively long, the exhaust gas from one exhaust cylinder 3 does not interfere with the exhaust gas from the next exhaust cylinder 3. Then, during the exhaust stroke of a certain exhaust cylinder 3, the positive pressure wave of the exhaust pulsation of the exhaust gas is inverted by the exhaust resonance phenomenon at the merging portion 14 to become a negative pressure wave, and the inverted negative pressure wave is generated at the end of the exhaust stroke of the cylinder 3 at the exhaust port. Propagate to 11 to accelerate the scavenging action.

When the engine is in the high speed rotation range, the on-off valve 17 is opened, but in this case also, the exhaust gas discharged from the left and right exhaust manifolds 10A and 10B via the exhaust pipes 13a and 13b joins.
They are merged at 14 and discharged to the merged exhaust pipe 15. On the other hand, the pressure vibration of the exhaust gas in the exhaust manifolds 10A and 10B is
Since the positive pressure wave of the exhaust pulsation of the exhaust gas in the exhaust stroke of a certain exhaust cylinder 3 is inverted by the exhaust resonance phenomenon in the volume portion 16a to become a negative pressure wave, the inverted negative pressure wave is the inverted negative pressure wave. At the end of the period, the scavenging action is promoted by propagating to the exhaust port 11. Even when the volume portion 16a is omitted, the scavenging action is promoted in substantially the same manner as above.

As described above, according to the exhaust device of the above-described embodiment, the communication pipe 16 that connects the exhaust manifolds 10A and 10B of the left and right banks 1A and 1B to each other and that is significantly shorter than the passage length of the exhaust pipes 13a and 13b is used. With the simple structure of providing the pipe 16, it is possible to promote the scavenging action in the high-speed rotation region where the exhaust resistance becomes large, reduce pumping loss, reduce the fuel consumption rate, and improve the output.

In the above embodiment, the on-off valve 17 is controlled based on the engine speed and is configured to open when the engine speed is higher than the predetermined engine speed.However, the on-off valve 17 is opened even when the engine speed is low and the load is low. As a result, the exhaust gas pressure can be reduced to reduce pumping loss.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a plan view of a V-type engine, FIG. 2 is a front view of the same, and FIG. 3 is a sectional view of a volume portion of a communicating pipe. E ... Engine, 1A / 1B ... Bank, 10A / 10B ... Exhaust manifold, 11 ... Exhaust port, 13a / 13b ... Exhaust pipe, 14 ... Merge part, 15 ... Merge exhaust pipe, 16 ... Communication pipe,
17 …… Open / close valve, 18 …… Actuator.

Claims (2)

(57) [Claims] 1. A transmission case is connected to one end of a V-type engine, an exhaust manifold connected to an exhaust port is provided for each bank, and exhaust passages of both exhaust manifolds are joined to connect to a combined exhaust passage. An exhaust device for a V-type engine, characterized in that a communication passage that connects the exhaust manifolds of both banks is provided laterally of the ends of both banks and above the mission case. 2. The merging portion of the exhaust passages of the two exhaust manifolds is arranged below the engine, the exhaust passages extending from the both exhaust manifolds to the merging portion are formed to have the same length, and a high rotation speed is provided in the middle portion of the communication passage. The exhaust system for a V-type engine according to claim 1, wherein an on-off valve that opens in the region is provided.