JPH0746735Y2 - Exhaust system for four cylinder four cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exhaust system for a four-cylinder, four-cycle engine mounted as power for a vehicle such as a motorcycle.

[Conventional technology and its problems]

While an engine for a vehicle is required to have a high output and high performance, it is used in the entire range of rotation, so an engine with a smooth output curve and good usability is required. The engine output is not only the performance of the combustion chamber etc., but also by effectively utilizing the exhaust pulsation by the exhaust pipe,
The efficiency of filling the combustion chamber may be increased to increase the output.
One way to do this is, for example, Shoukai 57-1672.
As shown in Japanese Patent No. 23, some exhaust pipes communicate with each other through a connecting pipe.

FIG. 5 is a diagram in which a part of an example of a four-cylinder, four-cycle engine c in which the exhaust pipes a are communicated with each other by a connecting pipe b is omitted. According to this example, # 2 and # 3
The exhaust pipes of FIG. 6 are communicated with each other by a connecting pipe b, and the charging efficiency is increased by utilizing each pulsation at the time of valve overlap in the cylinders # 2 and # 3, and the output line A shown in FIG. As indicated by (solid line), the output in the high speed range is higher than that of the output line B (broken line) of the four-cylinder, four-cycle engine in the case where communication is not established by the connecting pipe. However, in the medium and low speed range, this pulsation acts in the opposite direction to form an output valley A '.

As a means for preventing an output valley in the medium to low speed range, for example, as in the single cylinder engine disclosed in Japanese Utility Model Publication No. 58-27053, a muffler associated with the engine is provided with a resonance chamber, that is, a chamber. There is something.

It is conceivable to prevent the generation of the output valley in the medium and low speed range by simply combining with the exhaust pipes of # 2 and # 3 of the chamber multi-cylinder engine to prevent the generation of the output valley in the middle and low speed range. However, in actuality, there is no # 2 and # 3 exhaust pipe provided with a chamber, which is thus connected by a connecting pipe. This is because the connecting pipe and the chamber have opposite actions. That is,
The connecting pipe is, for example, as described in Japanese Utility Model Application Laid-Open No. 57-167223, which makes the exhaust pulsation effectively act on other cylinders by shortening the substantial exhaust pipe length, while the chamber is The above-mentioned JP-B-59-41290 and JP-B-62-316.
Since it has the effect of eliminating the exhaust pulsation as described in Japanese Patent No. 18, it is impossible to install both of them on the same exhaust pipes # 2 and # 3.

Therefore, in order to effectively prevent the generation of the output valley in the medium and low speed regions, it has been desired to provide a new technique that is not simply a combination of the conventional techniques.

[Purpose of device]

This invention is a new four-cylinder, four-cycle engine that can obtain a high output with a smooth output curve regardless of whether it is a multi-cylinder engine or not, in a high-medium-low speed range, and can also make the vehicle lighter and smaller. It is an object of the present invention to provide an exhaust device of.

[Means for achieving the purpose]

The present invention is intended to achieve the above object and is as follows. That is, the exhaust system of the four-cylinder four-cycle engine of the present invention is a four-cylinder four-cycle engine in which the ignition order is the cylinder order of # 1 # 2 # 4 # 3, and the rear end of the exhaust pipe connected to the exhaust hole end of each cylinder. In which the muffler is connected to one collecting pipe by connecting the exhaust pipes of # 2 and # 3 with a connecting pipe, and connecting them to the exhaust pipes of # 1 and # 4. The chamber was connected to a portion of the engine downstream of the bent portion near the exhaust hole, upstream of the connecting pipe, and near the bent portion.

[Function of device]

Since the exhaust pipes of # 2 and # 3 are connected by the connecting pipe, the output in the high speed range becomes high. Also,
Since 1 and # 4 are connected by the chamber, the output valley cannot be formed in the medium and low speed range. In the exhaust pipes # 1 and # 4, the chamber is arranged at a portion between the bent portion near the exhaust hole of the engine and the connecting pipe in the exhaust pipes and near the bent portion. The volume is as small as possible.

〔Example〕

 Hereinafter, the present invention will be described based on an embodiment shown in the drawings.

The engine 1 is a four-cylinder, four-cycle engine, and the ignition order is # 1- # 2- # 4- # 3. The tip of the exhaust pipe 2 is connected to the exhaust hole of each cylinder. The exhaust pipe 2 connected to the four cylinders is piped up to the lower side of the engine 1, and at the front end of one collecting pipe 3, the above #
1- # 2- # 4- # 3 are arranged in the circumferential direction in an order corresponding to the ignition order and are inserted and connected.

A muffler 4 is connected to the rear end of the collecting pipe 3.

As can be seen from FIG. 2, the exhaust pipes 2 of # 1 and # 4 are located at a position downstream of the bent portion near the exhaust hole of the engine 1 and upstream of the connecting pipe 6 as seen from the side. The chamber 5 is connected to a portion near the bent portion.

Exhaust pipe 2 of # 2 and # 3 is # 1 and # 4
The exhaust pipe 2 is communicated with the connecting pipe 6 at a position distant from the position where the chamber 5 is provided on the downstream side.

The connecting pipe 6 in which the exhaust pipes 2 of # 2 and # 3 are communicated with each other, when the valves of the cylinders of # 2 and # 3 overlap,
By utilizing each pulsation, the filling efficiency can be enhanced and the output curve in the high speed range can be enhanced.

Further, the chamber 5 of the exhaust pipe 2 of # 1 and # 4 can prevent the generation of the output valley in the medium and low speed range.

It should be noted that the pulsation is controlled by the capacity of the chamber 5 so as to match the rotation range so as to increase the output of the valley portion. In this way, a smooth high output can be obtained regardless of the high, medium, and low speed regions.

By the way, according to an experiment conducted by the present inventor, the chamber 5
In obtaining the effect of preventing the generation of the output valley in the medium and low speed range, it was found through repeated experiments that the mounting location becomes larger in proportion to the distance L from the exhaust hole of the engine 1. It was Therefore, in order to reduce the volume of the chamber 5, it is desirable to set the mounting location of the chamber 5 as close to the exhaust hole of the engine 1 as possible. Especially, since the exhaust pipe 2 to which the chamber 5 is attached is located in a narrow portion between the engine body and the front wheels, it is easier to attach the chamber 5 to the exhaust pipe if the volume of the chamber 5 is as small as possible. Further, if the chamber 5 is small, it is possible to suppress an increase in vehicle weight and an increase in size of the vehicle.

[Effect of device]

Regardless of the high, medium and low speed range, a high output can always be obtained with a smooth output curve, and the vehicle can be made light and small.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a perspective view, FIG. 2 is a partially longitudinal side view, and FIG. 3 is a graph showing the relationship between the position and volume of a chamber, and FIG. 6 is an output-rotation diagram of the present invention, FIG. 5 is a diagram for explaining the prior art, and FIG.
FIG. 6 is a prior art output-rotation diagram according to FIG. 1 ... Engine, 2 ... Exhaust pipe, 3 ... Collecting pipe,
4 ... muffler, 5 ... chamber, 6 ... connecting pipe.

Claims (1)

[Scope of utility model registration request] 1. A four-cylinder four-cycle engine in which the ignition sequence is the cylinder order of # 1 # 2 # 4 # 3, wherein the rear end of the exhaust pipe connected to the exhaust hole end of each cylinder is connected to one collecting pipe. When connecting a muffler to a collecting pipe, only the exhaust pipes of # 2 and # 3 are connected by a connecting pipe, and only the exhaust pipes of # 1 and # 4 are connected to the exhaust holes of the engine. An exhaust system for a four-cylinder, four-cycle engine, characterized in that a chamber is connected to a portion downstream of a bent portion closer to the bent portion and upstream of the connecting pipe and closer to the bent portion.