Views:0 Author:Site Editor Publish Time: 2020-10-26 Origin:Site
The function of the oil cooler is to cool the oil and keep the oil temperature within the normal working range. In the high-power enhanced engine, because of the large heat load, a lubricating oil cooler must be installed. When the engine is running, because the oil viscosity changes with temperature, some engines are equipped with a lubricating oil cooler, whose function is to reduce the oil temperature and maintain a certain viscosity of the lubricating oil. The lubricating oil cooler is arranged in the circulating oil circuit of the lubrication system.
Shell, inlet and outlet end caps, return end caps, tube groups, chips, fins, soldering fins, joints, spacers, baffles, etc.
The high-temperature lubricating oil flows into the shell from the inlet of the shell and flows into the shell through the divider. It flows horizontally through the outer surface of the cooling tube at high speed, releases heat to the cooling water in the tube, and then the temperature drops, and is discharged by the outlet tube; the cooling water flows in and out The inlet of the end cover enters into the tube bundle, and flows back in the cooling tube along the tube bundle. After absorbing the heat released by the lubricating oil, it is discharged from the outlet of the end cover, and the cold and hot media do not contact each other.
The nature of the oil
⑴ Viscosity. Viscosity is also one of the important properties of lubricating oil, which largely determines the formation of oil film. If the viscosity is too high, the oil cannot disperse quickly on the friction surface, and it is difficult to form a continuous and uniform oil film, which will increase the friction loss of the diesel engine; if the viscosity is too small, a reliable oil film may not be formed, and semi-liquid friction may occur, and the lubrication effect will be reduced. , Resulting in a decrease in the carrying capacity of the diesel engine. The viscosity of lubricating oil changes with temperature. As temperature increases, viscosity decreases. To evaluate the degree of viscosity of different varieties of lubricating oil with temperature, viscosity index or viscosity ratio is often used. The viscosity index of lubricating oil is obtained by comparing two standard oils. A viscosity index above 85 is called a high viscosity index, and a viscosity index less than 45 is a low viscosity index. The high viscosity index indicates that the viscosity of the lubricating oil changes little with temperature. It has enough viscosity at high temperature, but the viscosity is not too high at low temperature. Such lubricating oil has good quality. It shows that the viscosity of the lubricating oil changes with temperature to a small degree. It has enough viscosity at high temperature, but the viscosity is not too high at low temperature. This kind of lubricating oil has good quality. Viscosity ratio is also a performance index for evaluating the change of lubricating oil with temperature. It is the ratio of the viscosity of the lubricating oil at 50°C to the viscosity at 100°C. A low viscosity ratio means that the viscosity of the lubricating oil changes little within the specified temperature range and the quality is good.
⑵ Acid value. There are two kinds of acids contained in lubricating oil. One is organic acid, which is originally present in petroleum; the other is inorganic acid, namely sulfuric acid, which is cleaned and neutralized during the refining process. Residues in lubricating oil. In order to remove impurities in the lubricating oil, sulfuric acid must be used in the smelting, washed with fresh water, and then neutralized with an alkaline solution. Therefore, the inorganic acid in the lubricating oil refers to the residual sulfuric acid. It is very corrosive to metals and may cause pitting in parts such as bearings. Small amounts of organic acids have no corrosive effect on metals, but when the content of organic acids is high, lead and zinc will quickly undergo chemical changes, and copper will also oxidize to copper oxide. The acid value in lubricating oil is expressed in milligrams of potassium hydroxide required to neutralize one gram of lubricating oil. Lubricating oil will not only have a certain amount of acid value remaining in the refining process, but also increase the acid value due to oxidation and decomposition during use. The total value of these acids is called the total acid value, and the inorganic acid value is called the strong acid value (also called water-soluble acid). The rapid increase in the total acid value of the lubricating oil indicates that the quality of the lubricating oil is rapidly deteriorating, and sediments will be produced in the lubricating oil, and the color will turn black. According to regulations, the total acid value of lubricating oil is not allowed to exceed 2.5mg, otherwise the lubricating oil must be replaced.
⑶ Antioxidant stability. Antioxidant stability is the ability of oil to resist air oxidation. It can be measured by experiment. If a catalytic ring made of steel-copper wire is placed in a 300ml oil sample mixed with 60ml water and placed in an oxygen stream with a temperature of 95°C and a flow rate of 0.5 l/h, in the middle and end of the entire test process When it reaches the maximum acid value, the anti-oxidation stability of the lubricant can be judged. After the lubricating oil is oxidized, it not only increases the acid value, but also darkens the oil color and increases its viscosity due to the formation of gelatinous and pitch-like crystalline substances.
⑷ Demulsibility. It is a measure of the separation ability of oil-water mixtures. The degree of demulsification means that the same volume (40ml) of oil and water are stirred for 5 minutes at 54.6°C to form an emulsion. After standing, the oil and water are gradually separated. When the oil and water are basically separated (the emulsion is still less than 3ml), the required time is the degree of demulsification. The mixing of seawater or fresh water into the lubricating oil will emulsify the lubricating oil. After the lubricating oil is emulsified, foam will be formed, which will affect the pressure of the lubricating oil. In addition, after the lubricating oil is emulsified, the insoluble impurities will float in the oil and contaminate the friction surface. Make parts wear worse. After the lubricating oil is emulsified, foam will be formed, which will affect the pressure of the lubricating oil. In addition, after the lubricating oil is emulsified, the insoluble impurities will float in the oil and contaminate the friction surface. Make parts wear worse.