JPS59108815A - Exhauster for two-cycle engine - Google Patents

Abstract

PURPOSE:To reduce size while maintaining exhaust inertia effect by forming an exhaust tube section at the lower side of partition wall for splitting a box casing into two while communicating through an opening in the partition wall to the expanded section at the upper side and arranging expansion section, restriction section and muffler section below. CONSTITUTION:A box casing 2 is split up and down into two by a partition wall 4 where an exhaust tube section 6 communicating with the exhaust port of engine is formed on the lower member 3 by a partition wall 5 crossing perpendicularly with said wall 4. Exhaust gas passed through the exhaust tube section 6 will enter through an opening 4a into an expanded section 7 formed on the upper side of partition wall 4 then discharged through expansion section 8, restriction section 9 and muffler section 10 formed at the lower side of partition wall 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is mainly applicable to small-sized agricultural machines and the like. This invention relates to an exhaust system for a cycle engine.

Generally, in a two-cycle engine, in order to improve engine output, it is known that the exhaust inertia effect in the exhaust pipe is used to scavenge the burned gas in the cylinder chamber and to suck in fresh air. Immediately after the exhaust is opened, the high-pressure burnt gas is rapidly expanded in the expansion section of the exhaust passage,
This increases the pressure difference between the expansion section and the cylinder chamber, thereby actively sucking out the burnt gas in the cylinder chamber and sucking in fresh air.

However, conventionally, in an exhaust system for a two-stroke engine that utilizes the exhaust inertia effect, a certain length of the exhaust pipe section, expansion section, expansion section, throttle section, and muffling section are linearly arranged in order from the exhaust port side of the engine. Because of this arrangement, it can be applied to engines in light vehicles and motorcycles where there is sufficient mounting space, but it is difficult to apply it to general-purpose small engines such as agricultural machines. There was a problem with the weight and size.

Incidentally, as prior art, Utility Model No. 6, No. 773/G, No. 362, No. 362, Tokko Sho, No. 361, No. 7! In view of these points, the present invention provides an exhaust system for a two-stroke engine that can be made smaller and lighter while maintaining the exhaust inertia effect, and can be applied to general-purpose small engines such as agricultural machinery. The purpose is to provide

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to embodiments with reference to the drawings.

In Figure 1 and Figure 3, 1 is a box-shaped casing, and upper member 2 and lower member 6 are gaskets (not shown).
It is connected and fixed via. A partition wall 4 that divides the interior of the casing 1 into upper and lower halves is integrally formed on the upper member 2. Further, the lower member 6 is directly connected to the partition wall 4.

The partition walls 5 that are to intersect are integrally formed in a predetermined shape.

In the cage jig 1 in which the upper and lower side members 2 and 6 are connected and fixed, there is an exhaust pipe section 6 on one side (lower side) of the partition wall 4, one end of which communicates with the exhaust port of the engine (not shown). is formed in a spiral shape from the outside to the inside. The central end, which is the other end of the exhaust pipe section 6, communicates with an expanded section 7 formed on the other side of the partition wall 4 through an oblong opening 4a formed in the partition wall 4. Note that the expanded portion 7 extends from an upstream end 7a with which the central end of the exhaust pipe portion 6 is communicated.
The cross-sectional area of the passage gradually increases to form an expanded downstream end 7b.

The expanded downstream end 7b of the expanded portion 7 communicates through a semicircular opening 4d formed in the partition wall 4 to the expanded portion 8 formed on one side of the partition wall 4, which has a substantially semicircular cross section. There is.

The expansion section 8 is connected to the throttle section 9 and the muffling section 1° in this order between the expansion section 8 and the vicinity of the upstream end of the exhaust pipe section 6.

With the above configuration, the high-pressure burnt gas immediately after the exhaust is opened is rapidly expanded, and the expansion section 8. ! : Increases the pressure difference between the cylinder chamber and the engine, thereby actively sucking out the burnt gas in the cylinder chamber and sucking in fresh air, resulting in an exhaust inertia effect, resulting in a dramatic increase in engine output. It will be possible to achieve this goal.

Although the embodiment shown in FIGS. 1 and 2 can be manufactured from sheet metal or aluminum casting, the upper member constituting the casing 1 is shown in FIGS. As shown, an outer wall member 11 and a partition wall member 12 are separate members.
If configured by combining the above, all members 6.1
1.12 can be manufactured using aluminum die-casting, allowing for mass production and cost reduction.

Since the present invention is configured as described above, it can be made smaller and lighter while maintaining the exhaust inertia effect, and can be applied to general-purpose small engines such as agricultural machines.
Has excellent effects.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention, and FIG.
A vertical cross-sectional view of the exhaust system of a cycle engine, Figure 2 is the first
A sectional view of the lower member taken along the line ■-■ in the figure, FIG. 3 is a plan view of the upper member, FIG. 7(a) is a plan view of the outer wall member, and FIG.
Figure (C) is a sectional view taken along the line 8-A in Figure 7(a), and Figure 61 is a plan view of the partition wall member. 1...Casing, 4...Partition wall, 4a
, 4b hole, 6...exhaust pipe section, 7...
...Expansion part, 7d... Upstream end, 7b...
- Expansion downstream end, 8...Inflated part, 9...
Diaphragm part, 10... Sound deadening part 1 Mouth 20th 30th 50th

Claims (2)

[Claims] (1) A box-shaped casing is divided into two by a partition wall, and an exhaust pipe portion is formed on one side of the partition wall, one end of which communicates with the exhaust port of the engine, and the other end of the exhaust pipe portion is formed with the partition wall. is communicated with the expansion part on the other side of the partition wall through the opening, and an expansion part, a constriction part, and a muffling part formed on one side of the partition wall are sequentially connected to the expansion downstream end of the expansion part. An exhaust system for a two-stroke engine that is characterized by: (2) The exhaust system for a two-stroke engine according to claim 1, wherein the exhaust pipe portion is formed in a spiral shape.