First, the role of crankcase ventilation
Working engines always have a part of the combustible gas and air mixture of piston rings rushing to the crankcase. Gasoline vapor condensing into the crankshaft and condensed oil will become thin, which will cause performance degradation. The tail gas contains water vapor and sulfur dioxide. The water vapor condenses to form a foam, oil, which destroys the oil supply. This phenomenon is especially serious in winter. Sulfur dioxide and water form sulfite. The sulfite encounters oxygen in the air to produce sulfuric acid. The appearance of these amino acids not only degrades the oil, but also corrodes the parts. As the combustible mixture and exhaust gas flow into the crankcase, the crankshaft will increase the pressure inside the crankshaft oil seal, seal gaskets and other crankcases and lose leakage. The loss of water vapour in the atmosphere will increase the engine's polluting atmosphere.
The engine crankcase ventilation system can avoid or alleviate the above phenomena. Therefore, the engine crankcase ventilation device: 1. To prevent oil deterioration: 2. 2. To prevent crankshaft oil seal, seal gasket crankcase leak; To prevent oil from contaminating water vapor in the atmosphere.
Second, the characteristics and forms of crankcase ventilation
1 . natural ventilation
Since the crankshaft gas tank can directly enter the atmosphere, this is so-called natural ventilation. The ventilation structure in this way is relatively simple and easy to use, but the mixture of natural gas and petroleum vapor that enters the atmosphere and burns easily pollutes the atmosphere. So many modern engines are used. The way into the atmosphere is generally natural ventilation and ventilator style.
(1) ordinary type
The oil in the crankcase oil vapor tube is conducted in an atmosphere directly connected to the port. This method does not require special ventilation machinery, air pollution caused by water vapor of various types of oil directly entering the atmosphere, so it is suitable for some internal combustion engine tractors that do not require many.
(2) type respirator
The gas in the crankcase passes through the breathing device with the atmosphere. This device is a filter breathing device that absorbs harmful gases and prevents pollution of the atmosphere. Tusheng Nanjing Yuejin Group, a joint venture production, and Italy Iveco bus engine ventilator device. One cylinder of the respirator fixing bolt, the bottom side air inlet and the crankcase, and the upper part of the water outlet pipe use rubber and atmosphere. The respirator has two internal welded galvanized bowls to fill the line filters, oil mist and gas separation.
When the engine is working, the ventilation gas that is blown into the crankcase is taken from the air; it enters the respirator, the filter is filtered, separated, and finally the clean air is discharged from the rubber pipe. Since there are two filters, the oil mist is kept to a minimum to ensure a balance between the pressure inside the crankcase and the crankshaft to prevent oil and gas pollution from the atmosphere inside.
2 . Forced ventilation
Using the influence of the engine's intake and suction system, the natural gas pump is ventilated inside the crankshaft, which is the so-called forced ventilation method. The ventilation structure of this way is complicated, but it can penetrate into the crankcase and exhaust gas recovery of the internal flammable mixture, which is not only conducive to improving the economical engine, but also reducing the engine's pollution emissions, so it is widely used in modern automobile engines. The form of ventilation by the gas crankcase inside the pump, mandatory general type, one-way valve, oil and gas separation and integration.
(1) ordinary type
Only the hose connected to the crankcase and the intake pipe is generally forced ventilation. This structure is relatively simple to ventilate, and the fair pipe connection to other parts does not need to connect some small engines in the Middle East. General type of forced ventilation for crankcase of gasoline engine. With the air filter intake hose passing to the bonnet chamber, the chamber's tappet covers the air pipe through the inlet carburetor.
When the engine is operating, the intake of fresh gas from the carburettor and air purification filter through the hose through the hose, and the crankcase in the valve cover room.
(2) A non-return valve connects the crankcase and the intake pipe to a non-return valve to prevent the desire for oil-gasoline engines in the crankshaft, such as the EQ6100Q, and the Japanese Mitsubishi Pajero (cheetah), such as automotive engines. Forced ventilation for crankcase of one-way valve gasoline engine. The connection of the valve room actor's small air filter between the crankcase and the intake pipe was tracheostomy, and then entered the check valve at the intake pipe connection.
When the engine crankshaft, the check valve in the steam pipe is sucked into the cylinder, and fresh air is thrown into the crankcase air filter through the small valve chamber. The role of the one-way valve to prevent low-load engines from a small load intake manifold vacuum will be too large for the suction oil from the crankshaft. The crankcase ventilation system of one-way valve is mainly composed of valve, valve, valve seat and spring. When the vacuum in the engine idle pipe and a check valve seat are sucked in, the exhaust valve in the crankshaft enters the intake manifold through the small hole; as the engine load, the vacuum of the intake manifold vacuum drops according to the force The field opens above and then gradually increases the ventilation; the engine load, the valve is fully open, and the maximum amount of ventilation, which updates the air crankcase inside the play.
(3) Type of oil and gas separator
The pipes of the crankcase and the intake pipe are connected to the crankshaft in the oil and gas separator. The suction force is separated from the oil and natural gas, so that the liquid flows back to the crankcase. Steyr engine oil separator, which is the front end of the engine cylinder head.
As the engine works, oil and gas flow into the interior of the crankcase to manage the road to the separation of oil and gas, because the amount of oil and gas is separated by the plane tilting, so the oil liquid along the hillside flows back to the crankcase oil, and natural gas Water inlet of the gas connection pipe.
The connecting pipe between the crankcase and the intake pipe is not only a one-way valve, but also an oil-gas separator, which greatly reduces oil consumption and ensures the stability of engine oil under different conditions. Gasoline engine crankcase forced ventilation system integration.
Install the crankcase ventilation air filter before the cylinder head on the top cover, the crankcase ventilation socket filter is printed on the cover after the cylinder head is installed, the role of the filter is to separate oil and gas, so oil and gas are separated Device. Oil and gas filter inside the separator, the top of the filter separator must have better oil and gas separation; a check valve is located above to separate the oil and gas, thus making the thermal environment on the bond valve, plug, and many more.
When the engine is working, the combustible mixture leaking into the crankcase is under the condition of the intake manifold vacuum. The tappet chamber prevents the oil plate, crankcase ventilation filter socket, ventilation pipe and check valve from entering the engine intake manifold and mixing. Fresh mix cylinder in the fire. Fresh gas cylinder head, then cover the crankcase ventilation intake filter of the front cover into the crankcase.
Third, crankcase ventilation inspection and maintenance
1 . Check the pipeline condition
(1) The outlets of the crankcase ventilation pipe and the return pipe have been deleted, and related components (breathing apparatus, or check valve, or oil and gas separator) have been eliminated.
(2) Check whether the line is flat, or broken, leaking, etc., then clean and blow with compressed air.
(3) When disassembling and installing, in order to the contrary.
2 . Check condition check valve
For the crankcase forced ventilation system of one-way valve, we should focus on one-way check valve. We cannot guarantee normal crankcase ventilation if the adhesive has been opened or blocked by a check valve. When the valve keeps obstructing, poorly ventilated oil and natural gas in the engine load will blow into the atmosphere and pollute the environment; when the valve is opened, it will cause excessive oil consumption.
(1) Vacuum check valve
Screw the engine according to the one-way valve, then take a good ventilation pipe, the engine is idling, the finger should have a conscious vacuum at the end of the one-way valve opening, if raised, the mouth valve should have a "black, end" Sound, suction. If you feel unwell, apply a cleaning fluid to clean the check valve and ventilation pipe with a vacuum of your fingers or sound, then select it, if there is no line, you should change it.
(2) Check the movement of the valve
The screw engine is inserted into a check valve with a wooden stick according to the check valve. The plunger movement before and after this valve should be free. If the valve does not move the plunger should be cleaned or replaced.