Current situation and development of the hottest h

The present situation and development of hydraulic transmission oil

preface

fluid transmission includes gas (pressure) transmission and liquid transmission. Liquid transmission is divided into hydraulic transmission, hydraulic transmission and hydraulic viscous transmission. Hydraulic transmission is based on PACHA's law, which transmits power by the pressure energy of liquid; Hydraulic transmission is based on Euler equation, which transfers power with short change of liquid momentum; Based on Newton's law of internal friction, hydro viscous transmission transmits power with the viscosity of liquid

the basic components of hydraulic transmission are hydraulic coupling and hydraulic torque converter. The basic components of the hydraulic coupling are the pump wheel and turbine with several radial plane blades, which form the working chamber. The hydraulic transmission oil circulates at a high speed in the working chamber to transmit power. While the oil is involved in the movement with the follower pump wheel, it makes centrifugal movement due to the action of centrifugal force. It absorbs mechanical energy from the pump wheel (and input shaft) and converts it into the increment of moment of momentum (MVR). The high-speed fluid rushes from the pump wheel into the turbine for centripetal flow, releases the moment of momentum, drives the turbine (and output shaft) to rotate, and drives the working machine (and load) to do work. The basic components of hydraulic torque converter are pump wheel, turbine and guide wheel, which are working wheels with spatial (curved) blades, arranged in relevant order to form a working chamber. The hydraulic transmission oil is stirred by the pump wheel turbine in the working chamber, so that the liquid flow obtains the increment of momentum moment. After the guide wheel turns the direction of the liquid flow, it rushes into the turbine, releasing the momentum moment (kinetic energy) to drive the turbine to drive the working machine to rotate and do work

hydraulic components in China have developed rapidly in recent years. In 2003, the annual output of hydraulic couplings in China was about 70000 units. It is widely used in belt conveyor, scraper conveyor, ball mill, fan and compressor. I believe we will give you more knowledge about the technology. In the transmission of compressor, water pump and oil pump, we can improve the transmission quality and save energy. At present, the maximum output speed of hydraulic coupling in China is 6500r/min, the minimum power is 0.3kw, and the maximum power is 7100kw. The development trend of hydraulic coupling is high speed and high power

Germany Voith company is the most famous hydraulic coupling product in the world. According to the data, there are products with a rotational speed of 20000r/min and a power of 55000kw, which shows that there is still a considerable gap between China and it. Of course, high-power hydraulic components have higher requirements for hydraulic transmission oil

hydraulic torque converter is mainly used in engineering machinery, petroleum machinery and diesel locomotives. Hydraulic torque converter is mainly used in matching with internal combustion engine, and its speed range is 2000 ~ 3000r/min. Construction machinery is widely used, with a maximum power of about 700hp and an annual output of about 70000 sets. Petroleum machinery is less used, with a power of 1500hp. Diesel locomotives are less used, with power up to 300 "0hp

liquid viscous transmission is a new subject of liquid transmission, which is still in its infancy in China. Although hydro viscous transmission products (such as hydro viscous speed regulating clutch) are essentially different from hydraulic transmission products (such as speed regulating hydraulic coupling), due to their similar performance and the same purpose (speed regulating and energy saving), they are regarded as the same type in several technical activities (such as formulating development plans, standards, technical management, ordering activities, etc.) and have common characteristics with the hydraulic industry, so this paper sets up another chapter to introduce their product structure and transmission oil

I. performance characteristics and development of hydraulic transmission oil

as a working medium, hydraulic transmission oil is not only used to transmit power, but also used to lubricate bearings and gears. At the same time, it is also a carrier of slip heat, taking away heat. Hydraulic transmission oil is a complex subject that needs special research. It is directly related to the reliability, transmission efficiency and service life of hydraulic components. People should pay attention to it and carry out extensive and in-depth research

hydraulic transmission oil should meet the following requirements:

1. It should have appropriate viscosity

low liquid viscosity indicates that the internal friction of the liquid is small, and the flow resistance loss is small, which can reduce the hydraulic loss of hydraulic components; However, from the perspective of lubrication and sealing, the viscosity should not be too low. Therefore, on the premise of meeting the requirements of lubrication and sealing, try to use liquid with low viscosity to improve the transmission efficiency of hydraulic components. At the same time, the viscosity and temperature of the liquid are required to be good, so as to maintain effective lubrication and sealing at high or low temperatures

2. Have a larger weight

because the torque and power transmitted by the hydraulic components are directly proportional to the weight of the working fluid, the higher the weight of the fluid, the better

3. Stable performance

not easy to produce foam, aging and precipitation

4. The acid value should be low

it should be neutral to the seal, have good compatibility, do not swell, do not dissolve, and have no corrosive effect on the metal

5. Have a high flash point and a low solidifying point

the oil temperature changes greatly when the hydraulic element works, sometimes up to 160 ℃, so the flash point is required to be higher than 180 ℃, and the solidifying point is required to be low (-20 ℃), which is conducive to the starting of the hydraulic element in low temperature environment

6. Have good lubrication performance

the liquid should have enough oiliness to adhere to the surface of parts and play a good lubrication role

at present, there are many kinds of working fluids used in hydraulic transmission at home and abroad. In addition to various petroleum based products, there are also clear water or other non combustible liquids (used in underground coal mines to prevent ignition and explosion). Domestic hydraulic components usually use No. 6 hydraulic transmission oil (also use No. 8 hydraulic transmission oil), sometimes replaced by No. 22 turbine oil

diesel locomotives have special oil, which is required to have a service life of not less than 2000 hours. New equipment is required to load oil for the first and second oil changes after 100 hours and 500 hours of initial operation, and it can still be used after filtration

in one of the following cases, it is necessary to replace the new oil:

when the water content is greater than 0.2%

the viscosity at 50 ℃ is 6 centistokes higher than that of new oil

when mechanical impurities (benzene insoluble matter) reach 0.2%

when there are water-soluble acid-base or high acid value

when too much foam affects the transmission power

the above items also have a certain reference value for hydraulic transmission oil other than diesel locomotive special oil

II. Brand comparison of hydraulic transmission oil at home and abroad (omitted)

III. requirements of hydraulic viscous transmission on transmission oil

hydraulic viscous transmission can be divided into two categories according to whether the thickness of oil wax changes during operation. One category is hydraulic viscous transmission with constant oil film thickness during operation. For example, the oil film thickness of silicon oil fan clutch is fixed, and the oil filling degree in the working chamber is changed during operation to adjust the output speed. The other is the hydro viscous transmission with variable oil film thickness in operation. This kind of hydro viscous transmission products include hydro viscous speed regulating clutch, hydro viscous brake, hydro viscous dynamometer, hydro viscous coupling and hydro viscous speed regulating device. At present, hydraulic viscous speed regulating clutch, hydraulic viscous speed regulating device and silicone oil fan clutch are widely used

1. Hydro viscous speed regulating clutch and transmission oil

hydro viscous speed regulating clutch drives power through several oil films between its driving and driven friction plates, Depending on the viscosity of the oil, the active friction plate "pulls" the driven friction plate to rotate in the same direction, and the transmission torque is proportional to the viscosity of the oil and the "slip" between the two plates, but not to the thickness of the oil film (plate gap) In inverse proportion. The active friction plate and input shaft are connected with the power machine, and the input speed can be regarded as a constant. The driven friction plate and output shaft are connected with the working machine, and the output speed changes with the control pressure. If the control pressure of the spherical cylinder is large, the oil film between the plates becomes thin, and the output speed increases, and vice versa. When the control pressure is large enough, the driving and driven friction plates are bonded and become direct transmission. When the control pressure is small enough, the driving and driven friction plates are separated, and the output speed is zero. In the process of the speed ratio of the hydro viscous speed regulating clutch changing from 0 to 1, the friction between the plates presents the characteristics of liquid friction → mixed friction (mechanical liquid) → (pure mechanical) boundary friction. Therefore, the hydro viscous speed regulating clutch has separation condition, speed regulating condition and engagement condition in the speed regulating process

the function of working fluid in hydro viscous transmission is to transmit power, cool, dissipate heat and lubricate. It should have the following properties:

(1) it has appropriate viscosity

(2) good lubrication performance (oiliness and extreme pressure)

(3) good oxidation stability

(4) has higher specific heat capacity and higher thermal conductivity

in addition to the above requirements, the working fluid should also have rust prevention, anti foam ability, low freezing point, high flash point, non-volatile, non-toxic, etc

at present, domestic hydro viscous speed regulating clutches mostly use No. 8 hydraulic transmission oil as the working fluid

at present, domestic hydraulic viscous speed regulating clutch has TL type and HC type, and the rated speed is mostly 1500r/min, and some are 3000r/min. The minimum transmission power is 75kW and the maximum is 1100kw

like the speed regulating hydraulic coupling, the hydro viscous speed regulating clutch is adjusted downward at the speed of the drive motor, and the power is small and the efficiency is low at low speed. For this reason, a gear drive is added before the input or after the output end of the hydro viscous speed regulating clutch to adapt to the matching with the power machine or the working machine, so a new device - Hydro viscous speed regulating device is produced

2. Hydro viscous speed regulating device

currently, there are two types of hydro viscous speed regulating devices with different structures produced and applied. One is the parallel shaft hydro viscous speed regulating device produced by Philadelphia gear company in the United States, with input speed of 1785r/min, output speed of 5000r/min and transmission power of 5200kw. The belt conveyor of Antaibao coal mine in Shanxi Province uses smaller specifications. Its transmission oil system was brought by the United States. Baoding spiral pulp factory has designed and produced products with similar structure. The other is the CST hydro viscous speed regulating device of American dodge company, which is equipped with a hydro viscous speed regulating clutch (the driven friction plate is fixed) on the output end of the cylindrical gear planetary gear train reducer differential gear train and the large gear ring output in parallel with the output shaft (connected with the sun gear). When starting, the hydro viscous speed regulating clutch is in the separation condition (idling), gradually increasing the control pressure. When its transmission torque is equal to the torque borne by the output shaft, The output shaft (with load) starts to rotate, and continues to increase the control pressure until the connection condition, then the output bearing bears the output of all power. Cinsin well embodies the sustainable development concept of Bayer Material Technology. St hydro viscous speed regulating device is called the soft starting system of large belt conveyor, and has been applied to large belt conveyor in coal mines in China. CST Series products have an input speed of 1483r/min, a rated reduction ratio of 15.38 ~ 57.66, and a transmission power range of 702 ~ 3115kw. CST Series products are supplied with special hydraulic transmission oil from the United States

3. Silicone oil fan clutch and working fluid

there are several zonal annular blades on the driving and driven plates of silicone oil fan clutch, and their annular blades are inserted alternately to form several circular annular gaps (oil films), which use the viscosity of the oil film in these gaps to transmit power. During the working process, the oil film thickness remains unchanged, and the speed can be adjusted by changing the oil charge and the shear area of the oil film

the automobile engine can only have higher fuel efficiency at the appropriate temperature, and neither supercooling nor overheating is appropriate. The driving plate of silicone oil fan clutch for automobile is connected with the engine, and the driven plate is connected with the fan. The working fluid is silicone oil with high viscosity. The oil filling amount is controlled by the feeling of the temperature sensor on the air flow temperature behind the cooling water tank. When the cooling water temperature of the engine is low, the air flow temperature is low, the oil charge of the temperature sensor is small, the oil film shear area is small, and the transmission torque is small, the fan speed is low, and the cooling capacity of the engine is low. On the contrary, when the engine cooling water temperature is high, the fan speed is high, which improves the cooling effect of the engine. This will keep the engine at the most suitable temperature