CN111520212A

CN111520212A - Method for preventing water vapor of crankcase ventilation system from condensing

Info

Publication number: CN111520212A
Application number: CN202010362922.2A
Authority: CN
Inventors: 黎华文; 李湘华; 卢祥林; 向本杰
Original assignee: Guangxi Yuchai Machinery Co Ltd
Current assignee: Guangxi Yuchai Machinery Co Ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-08-11

Abstract

The invention discloses a method for preventing water vapor of a crankcase ventilation system from being condensed, relates to the field of crankcase ventilation systems, and solves the technical problems that liquid water condensed from waste gas is mixed with engine oil to cause whitening and deterioration of the engine oil, and condensed water is easy to freeze in a pipeline of a closed crankcase ventilation system to cause blockage of the pipeline. The method comprises the following steps: high temperature and high pressure gas is introduced into the crankcase to mix with the exhaust gas to reduce the partial pressure of water vapor in the exhaust gas. The invention has small improvement difficulty and high reliability, and greatly reduces the probability of condensing the water vapor in the waste gas into liquid water, thereby reducing the risks of whitening and deteriorating the engine oil and blocking a flow passage of a closed crankcase ventilation system due to the entering of condensed water.

Description

Method for preventing water vapor of crankcase ventilation system from condensing

Technical Field

The present invention relates to crankcase ventilation systems, and more particularly, to a method of preventing condensation of water vapor in a crankcase ventilation system.

Background

The prior state of the art six-crankcase ventilation model is shown in fig. 1. Fresh air (hereinafter referred to as new air) in the atmosphere enters a supercharger compressor after being subjected to air filtration to be changed into high-temperature and high-pressure new air, the temperature of the new air is reduced after passing through an intercooler, the new air enters a combustion chamber through an air inlet pipe and is subjected to combustion reaction with fuel in the combustion chamber, most of waste gas generated after combustion reaches a supercharger turbine through an exhaust pipe, a turbine is driven to rotate to apply work to the compressor, and finally the waste gas is exhausted into the atmosphere through a post-processor; and the other small part of waste gas (about 0.7-1.0%) leaks into the crankcase through the gaps among the piston, the piston ring and the cylinder hole, and then enters an air inlet pipeline in front of the supercharger compressor after passing through an oil-gas separator of a closed crankcase ventilation system.

Most of the fuels used in gas engines and methanol engines are methane (CH4) and methanol (CH4O), the fuel has a high hydrogen content, the concentration of water vapor in the exhaust gas generated after complete combustion in the combustion chamber is high, and the partial pressure of the generated water vapor is close to 20% particularly when equivalent combustion is adopted in a national six-gas engine. Water vapor condenses out when the temperature of the exhaust gas leaking into the crankcase drops to around 60 c. The condensed liquid water is mixed with the engine oil in the oil pan, the top surface of the cylinder cover and the wall surface of the inner cavity of the cylinder cover hood, so that the engine oil is whitish and deteriorated. When the temperature is further reduced, such as in cold winter, part of condensed water is frozen in an oil-gas separator and front and rear pipelines of the closed crankcase ventilation system, so that a flow passage is blocked, and the normal operation of an engine is influenced.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art, and provides a method for preventing water vapor of a crankcase ventilation system from condensing, so that the probability of whitening and deterioration of engine oil and the probability of icing and blockage of a closed crankcase ventilation system pipeline are effectively reduced.

The technical scheme of the invention is as follows: a method of preventing condensation of crankcase ventilation system water vapor, the method comprising: high temperature and high pressure gas is introduced into the crankcase to mix with the exhaust gas to reduce the partial pressure of water vapor in the exhaust gas.

In a further improvement, the high-temperature and high-pressure gas is introduced into the crankcase from a pipeline between the supercharger compressor and the intercooler through a branch.

Furthermore, the amount of the high-temperature and high-pressure gas introduced into the crankcase is 0.5 to 1.5 percent of the gas outlet amount of the supercharger compressor.

Furthermore, a throttling device is arranged on the branch.

Further, the throttling means is an orifice or a throttle valve.

Advantageous effects

The invention has the advantages that:

1. a certain amount of high-temperature and high-pressure gas is introduced into the crankcase to mix the gas with the waste gas so as to reduce the partial pressure ratio of water vapor in the waste gas, so that the water vapor in the waste gas is not easy to condense and generate liquid water, and the probability of whitening and deterioration of engine oil and icing and blocking of a closed crankcase ventilation system pipeline is effectively reduced.

2. The position of the introduced high-temperature and high-pressure gas is a pipeline behind a supercharger compressor and in front of an intercooler, the pressure of new gas at the position is higher, and the gas can smoothly enter a crankcase under the action of pressure difference; in addition, the temperature of the fresh air at the position is higher, more water vapor can be contained in a saturated state, more water vapor in the waste gas can be absorbed after the fresh air enters the crankcase of the engine, and the probability of condensing the water vapor into liquid water is greatly reduced. In addition, fresh air at the position is filtered through the air filter, so that the air is ensured to be clean, large-particle impurities cannot be brought into an engine crankcase, and engine oil is ensured not to be polluted.

Drawings

FIG. 1 is a diagram of a prior art crankcase ventilation system model of an engine;

FIG. 2 is a block diagram of a crankcase ventilation system model of the present invention.

Detailed Description

The invention is further described below with reference to examples, but not to be construed as being limited thereto, and any number of modifications which can be made by anyone within the scope of the claims are also within the scope of the claims.

Referring to fig. 2, a method of preventing water vapor condensation in a crankcase ventilation system of the present invention comprises: high temperature and high pressure gas is introduced into the crankcase and mixed with the exhaust gas to reduce the partial pressure of water vapor in the exhaust gas. Because more vapor that high temperature high pressure gas can hold, consequently, it can absorb the vapor in the waste gas after getting into the crankcase to make the vapor in the waste gas be difficult for the condensation, be difficult to produce liquid water, effectual reduction machine oil turns white, rotten and the probability that closed crankcase ventilation system pipeline freezes and blocks up.

High-temperature and high-pressure gas is introduced into a crankcase from a pipeline between a booster compressor and an intercooler through a branch. That is, in the present embodiment, the gas introduced into the crankcase is the fresh gas with high temperature and high pressure. The pressure of fresh air in a pipeline between the supercharger compressor and the intercooler is high, and the fresh air can smoothly enter the engine crankcase under the action of pressure difference; in addition, the fresh air temperature at the position is higher, and more water vapor can be contained in the saturated state. Therefore, the water vapor in the waste can be absorbed more after entering the crankcase of the engine, so that the probability of condensing the water vapor into liquid water is greatly reduced, and the risks of whitening and deteriorating the engine oil and blocking the flow channel of the closed ventilation system of the crankcase due to icing of the condensed water are effectively reduced.

In addition, fresh air in a pipeline between the supercharger compressor and the intercooler is filtered through the air filter, so that the cleanness of the air is ensured, large-particle impurities cannot be brought into an engine crankcase, and engine oil is prevented from being polluted.

Wherein, a throttling device is arranged on the branch. The throttling device is used for controlling the air inflow introduced into the crankcase, and the new air flowing out from the air outlet end of the supercharger compressor is introduced into the crankcase.

The throttle device is an orifice or throttle valve that allows for control of the amount of fresh air entering the crankcase.

The amount of the high-temperature and high-pressure gas introduced into the crankcase is 0.5 to 1.5 percent of the gas outlet amount of the supercharger compressor. Because the high-temperature high-pressure gas can contain more water vapor, the water vapor is not easy to condense, and the more high-temperature high-pressure gas is introduced into the crankcase, the lower the water vapor partial pressure is, and the more difficult the condensed water is to be generated. However, when too much gas is introduced, the pressure in the crankcase is increased, and the amount of fresh air entering the combustion chamber is reduced, which affects the combustion quality in the cylinder and is not favorable for the operation of the engine. Therefore, the introduced fresh air is controlled to be 0.5-1.5% of the total fresh air, the influence on a combustion chamber can be effectively reduced, and the problem of too high pressure of a crankcase of the engine cannot be caused.

Preferably, the amount of the high-temperature and high-pressure gas introduced is 1% of the gas outlet amount of the supercharger compressor.

Tests have shown that when the diesel engine is in operation, the partial pressure of water vapour is 10kPa ± 0.2kPa when the ratio of the amount of exhaust gases leaking into the crankcase to the amount of gases introduced is 1:1, and that the engine oil is less whitish. The fuel of the gas engine or the methanol engine generates more moisture than the diesel engine after combustion, and the leakage amount of the exhaust gas is not more than 1% of the total amount of the exhaust gas under normal conditions. Therefore, the amount of the introduced high-temperature and high-pressure gas is controlled to be 1% of the gas outlet amount of the supercharger compressor, the condition that engine oil in a gas engine or a methanol engine turns white and goes bad can be effectively reduced, and the probability of icing and blocking of a pipeline of a closed crankcase ventilation system can be greatly reduced.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various changes and modifications without departing from the structure of the invention, which will not affect the effect of the invention and the practicability of the patent.

Claims

1. A method of preventing condensation of water vapor in a crankcase ventilation system, the method comprising: high temperature and high pressure gas is introduced into the crankcase to mix with the exhaust gas to reduce the partial pressure of water vapor in the exhaust gas.

2. The method of claim 1, wherein the high temperature, high pressure gas is routed from a conduit between the booster compressor and the intercooler to the crankcase.

3. The method of claim 2, wherein the amount of high temperature, high pressure gas introduced into the crankcase is between 0.5% and 1.5% of the booster compressor bleed air volume.

4. A method of preventing condensation of water vapor in a crankcase ventilation system according to claim 3 wherein a restriction is provided in said branch.

5. A method of preventing condensation of water vapor in a crankcase ventilation system according to claim 4 wherein the restriction is an orifice or throttle.