CN202628293U - Two-stroke gasoline engine cylinder block - Google Patents

Abstract

The utility model discloses a two-stroke gasoline engine cylinder block and relates to the technical field of gasoline engines. The two-stroke gasoline engine cylinder block consists of a cylinder block basal body. The cylinder block basal body is symmetrically provided with double scavenging air ducts; each scavenging air duct is provided with a guide rib and a partition; the corresponding scavenging air duct is divided into a first scavenging air duct and a second scavenging air duct by the guide rib; the partition is arranged in every air inlet; a reinforcing rib is arranged between joint surfaces of air outlets and a tank body; and blades at the top part of the cylinder block basal body are vertical. As such a structure is adopted, compared with the prior art, the two-stroke gasoline engine cylinder block disclosed by the utility model has the advantage that the exhaust emission is greatly reduced.

Description

A cylinder block of a two-stroke gasoline engine

technical field

The utility model relates to the technical field of gasoline engines, in particular to a cylinder body for a two-stroke gasoline engine.

Background technique

In view of the fact that European and American countries are increasingly strict on engine exhaust emissions, gasoline engines entering the European and American markets in the future must comply with environmental protection emissions. The scavenging process of a two-stroke gasoline engine is divided into three stages: free exhaust, scavenging, and additional exhaust. Free exhaust stage: the exhaust port is opened until the fresh charge enters the cylinder, and the exhaust port is generally opened 60o ~ 75o (CA ) before the bottom dead center. When the exhaust port is just opened, the cylinder pressure is relatively high, about 300-600 kPa, and the pressure ratio p/pr exceeds 1.9, which is supercritical exhaust. At this stage, the exhaust flow has nothing to do with the state of the gas in the exhaust pipe, but only depends on the state of the gas in the cylinder and the size of the flow section of the exhaust port. The free exhaust stage is the most important stage in the ventilation process of the two-stroke internal combustion engine, and it also includes supercritical exhaust and subcritical exhaust, and about 70% to 80% of the exhaust gas is discharged. Scavenging stage: With the downward movement of the piston and the rapid outflow of exhaust gas, the gas pressure in the cylinder drops sharply, which can form a higher vacuum. Subsequently, the openings of the scavenging port and the exhaust port are large, and the scavenging air flow enters the cylinder through the scavenging port, and the exhaust gas in the cylinder is pressed from the exhaust port to the exhaust pipe to realize scavenging. Extra exhaust stage: from the closing of the scavenging port to the closing of the exhaust port, it is the additional exhaust stage. Due to structural reasons, the closing time of the scavenging port of the two-stroke engine is earlier than that of the exhaust port. At this stage, due to the upward displacement of the piston and the inertia of the exhaust gas flow, part of the mixture of exhaust gas and fresh charge continues to be discharged until the exhaust port is closed. For engines where the scavenging port closes later than the exhaust port, this phase is called the post-charge phase because of the additional addition of fresh charge.

The scavenging characteristics of the two-stroke gasoline engine cylinder block in the prior art:

The air exchange time is short and the air exchange quality is poor; during the scavenging period, more fresh charge will flow directly into the exhaust pipe through the exhaust port, which increases the consumption of fresh charge.

The process of intake and exhaust is carried out at the same time, the fresh charge and exhaust gas are easy to mix, and the coefficient of residual exhaust gas is relatively large.

High emissions, for carburetor-type two-stroke gasoline engines, due to the fact that more fresh charge short-circuits and flows directly into the exhaust pipe during scavenging, resulting in high unburned HC emissions. the

In terms of emission control, due to the high proportion of HC in the exhaust gas, the emission of HC must be controlled to control the emission, and the emission of HC is mainly caused by the direct discharge of the unburned mixture caused by the mixing of fresh mixed gas and exhaust gas during the scavenging process. Two-stroke The UHC produced by gasoline engine combustion is about 300-400ppm, and there are about 1500 (small load)-5000 (large load) UHC in the usual emissions, most of which come from the scavenging process. The relationship between the scavenging passage and the intake air volume mainly depends on the minimum cross-sectional area of the scavenging passage and the actual cross-sectional area of the air port. In addition, the angles of the sides of the scavenging passage are also the main influencing factors, which have a greater impact on engine emissions.

Contents of the invention

In order to solve the technical problem that the emission of the traditional cylinder block does not meet the standard, by optimizing the structure of the cylinder block, a two-stroke gasoline engine block that promotes the full combustion of the mixture gas, reduces exhaust gas emissions, and is beneficial to environmental protection is provided.

The cylinder block of the two-stroke gasoline engine of the utility model is composed of a cylinder body, on which double scavenging passages are symmetrically arranged, and guide ribs and partitions are arranged on the scavenging passages, and the guide ribs divide the scavenging passages into the first scavenging passages and the second scavenging channel; a partition is arranged in the air inlet, and a reinforcing rib is arranged between the exhaust port and the joint surface of the box body; the top blade of the cylinder body is vertical, that is, perpendicular to other blades.

The scavenging angles of the scavenging channel are: α=150°±10°, β=120°±10°, θ=100°±10°.

The utility model adopts the above structure, that is, the cylinder body belongs to the double scavenging air passage, has the best scavenging angle, and has a reasonable shape of the intake and exhaust ports, which is very beneficial for reducing emissions, especially reducing HC+NOx emissions; It greatly reduces the emission of exhaust gas, fully meets the requirements of low emission, and its comprehensive performance is greatly improved compared with the previous cylinder block.

Description of drawings

Fig. 1 is the front view of the utility model two-stroke gasoline engine cylinder block;

Fig. 2 is the main cross-sectional view of the cylinder block of the two-stroke gasoline engine shown in Fig. 1;

Fig. 3 is the right view of the cylinder block of the two-stroke gasoline engine shown in Fig. 1;

Fig. 4 is the bottom view of the cylinder block of the two-stroke gasoline engine shown in Fig. 1;

Fig. 5 is the enlarged schematic diagram of the shape and structure of the intake port of the cylinder block of the two-stroke gasoline engine shown in Fig. 1;

Fig. 6 is an enlarged schematic diagram of the shape and structure of the exhaust port of the cylinder block of the two-stroke gasoline engine shown in Fig. 1 .

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in detail:

As shown in the accompanying drawings, in the figure: 1. Double scavenging air ducts, 2. Guide ribs, 3. Vertical cooling fins, 4. Reinforcing ribs, 5. Next door; the scavenging angles in Figure 4 are: α=150° ±10°, β=120°±10°, θ=100°±10°.

It is composed of a cylinder base, on which double scavenging channels are arranged symmetrically, on which guide ribs and partitions are arranged, and the guide ribs divide the scavenging channels into a first scavenging channel and a second scavenging channel; A partition is arranged in the air inlet, a reinforcing rib is arranged between the exhaust port and the joint surface of the box body, and the top blade of the cylinder body is vertical, that is, perpendicular to other blades.

Claims (2)

1. a two-stroke gasoline engine cylinder block is made up of a cylinder base body, and is characterized in that: double scavenging passages are arranged symmetrically on the cylinder base body, guide ribs and next walls are set on the described air sweep passages, and the guide ribs The scavenging channel is divided into a first scavenging channel and a second scavenging channel; a partition wall is provided in the air inlet, and a reinforcing rib is provided between the exhaust port and the joint surface of the box body; the cylinder body The top blade of the substrate is vertical, that is, perpendicular to the other blades. 2. The cylinder block of a two-stroke gasoline engine according to claim 1, wherein the scavenging angles of the scavenging passages are: α=150°±10°, β=120°±10°, θ=100° ±10°.

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