The dynamic performance of modern vehicles is constantly improving, and people pay more and more attention to vehicle safety and comfort. Therefore, higher requirements are placed on the deceleration and braking performance of vehicles. Because the hydraulic retarder has the advantages of high-speed braking torque, large braking, smooth noise, small life and long volume, it has been widely used in military vehicles such as heavy-duty trucks for military vehicles and construction machinery.
Structure and working principle of 2 hydraulic retarder Hydraulic retarder structure 12. The moving wheel 2 and the fixed wheel 6 together form a working chamber. The moving wheel is connected to the rotating part of the transmission system through the transmission shaft 1, and the fixed wheel is connected with the fixed part. When the hydraulic retarder is working, the control system controls the oil-filling mechanism to fill the working chamber with oil, and the oil is circulated in the working chamber under the driving of the moving wheel blades, so that the momentum moment changes, and the oil exerts a reaction force on the moving wheel, resulting in Braking torque. The impact and friction losses of the oil in the working chamber are converted into heat, which is dissipated through the heat dissipation system.
When the hydraulic retarder is filled with oil, the braking torque is calculated as follows: the density of the working fluid is 13 , which is the working speed of the hydraulic retarder, and rmimZ is the effective diameter of the circulating reducer of the hydraulic retarder, m.
1. Transmission shaft 2. Moving wheel 3. Reducer housing 4. Oil inlet 5. Oil outlet 6. Fixed wheel 7. Valve 8. Bearing can be seen from Equation 1, 7 is proportional to and 12, and The amount of oil is related. In order to improve the braking performance of the hydraulic retarder, the hydraulic retarder can be arranged at the high speed of the transmission chain by increasing and improving, and the higher braking performance can be achieved with a smaller radial size. . The disadvantage of the hydraulic retarder is that its braking torque drops faster when the speed decreases, so it is often used as an auxiliary brake in combination with other braking methods to form a combined brake mechanism.
The braking torque generated by the hydraulic retarder is related to the working fluid occupying the volume of the working chamber. The hydraulic retarder used in the actual project is not fully filled with liquid, but is partially filled. Generally speaking, the volume of the body is only about 90% of the volume of the working chamber, and the auxiliary system of the data acquisition system of the flywheel group of the inertia of the test piece is reserved.
Leaving air and water vapor 3.
The relative filling amount is defined as the ratio of the working liquid volume to the working chamber volume, that is, the product.
The torque test curve generated by the liquid filling amount 1. The medium speed ratio; the magnitude of the zero moment, thereby approximating the braking torque generated by the hydraulic retarder under partial liquid filling conditions is the hydraulic retarder The braking torque is approximately proportional to the liquid filling amount, and the braking torque can be controlled by controlling the filling amount of the speed reducer.
When the hydraulic retarder is partially filled, there will be a free surface with zero pressure in the liquid circulation core. At this time, the pressure of the oil discharge port of the hydraulic retarder is related to the flow velocity of the moving wheel outlet and the thickness of the liquid ring. Under the same working conditions, the thicker, the higher the pieces. A throttle valve is arranged at the oil outlet of the hydraulic retarder. When the flow area of ​​the throttle valve is reduced, the flow rate discharged through the throttle valve is reduced, which is lower than the flow rate of the oil supply to the hydraulic reducer. Breaking the balance, the inlet flow rate of the hydraulic retarder oil supply is greater than the outlet flow rate, so the liquid filling volume in the hydraulic retarder chamber begins to increase, the liquid ring is gradually thickened, and the flow is also increased, and the flow rate flowing through the throttle valve is discharged. It also gradually increased. When the flow rate equal to the flow rate of the oil supply pump into the hydraulic retarder is reached, a new balance is reached, and the liquid filling amount does not change; when the throttle opening degree is increased, the liquid filling amount is decreased. Therefore, the purpose of adjusting the output characteristics of the throttle hydraulic retarder.
3 Test study 3.1 Test equipment Test equipment and performance parameters As follows: a test piece is a type of hydraulic retarder suitable for a certain vehicle, the circulation circle diameter is 375, the number of blades of the drive wheel is 20, and the number of blades of the fixed wheel is 24, the axial direction of the oil inlet and outlet port 4, and 4 are both 0.0375! . 5 is a hydraulic retarder for testing.
b. The maximum output power of the power unit is 330. The maximum torque is 1320. The maximum speed is 2400. The C gearbox is used to match the speed and torque of the power unit and the test piece.
d. The inertia flywheel group is converted to 33.16 according to the vehicle inertia.
6. Elbow 020 type throttle valve, diameter 2, 1.
1g. The heat dissipation system uses a plate heat exchanger, and the heat dissipation area is the working fluid for the No. 8 hydraulic transmission oil. i. The data acquisition system includes industrial control computer data acquisition and processing software, temperature pressure and speed torque sensor and flow meter.
1. Fuel tank 2. Oil filter 3. Gear pump 4. Relief valve 5. Hydraulic 3 moving wheel working speed is 560, reducer 6. Throttle 7. Flow meter 8. Inlet pressure before heat exchanger, it The function is to automatically adjust the flow rate of the oil supply system through the reducer according to the internal flow pressure change law of the different working conditions of the reducer; by adjusting the different opening degrees of the throttle valve 6 in the outlet oil passage, the hydraulic reducer is different The amount of liquid filled. 3.2 Test content and data analysis 3.2.1 Basic performance test of hydraulic reducer When the basic performance test is carried out, the inertia flywheel set is temporarily not connected.
Start the pump station, adjust the throttle valve to make it at the maximum opening degree, and start the power unit after the oil-filled state is stable. In the test, the oil filling amount of the hydraulic retarder was adjusted by adjusting the opening degree of the throttle valve.
Under the condition of 650700, adjust the opening degree of the throttle valve, change the oil filling amount in the reducer, and record the moving wheel speed and corresponding braking torque of the hydraulic retarder under different steady oil speeds under different steady speeds, and the speed reducer Inlet oil pressure outlet oil pressure oil gentle flow.
According to the test data measured at different speeds, the torque coefficient of the tested parts at different filling amounts is calculated by using Equation 1. When the input speed is timed, the oil filling amount in the hydraulic retarder chamber is related to the outlet pressure, and the outlet pressure is related to the pressure in the chamber, and the rotational timing timing outlet pressure is proportional to the pressure in the hydraulic retarder chamber. According to the test data, when the working speed of the hydraulic reducer is 560rZmiru600rZmiru650rZmirn700rZmirfrS force reducer pressure and torque coefficient for a long time, the curve is fitted.
It can be seen that the boiling torque coefficient continues to increase with the pressure inside the cavity. Due to the different rotational speeds, the critical cavity pressure is different, and the long straight does not rise, but is maintained at the maximum value. When the rotational speed of the hydraulic retarder is timing, the pressure in the cavity of the hydraulic retarder is proportional to the liquid filling amount. Therefore, it can be considered that in the liquid filling process, as the liquid filling amount of the hydraulic retarder increases, the number of people 7 also increases; in the full state, the value of the hydraulic retarder reaches the maximum range, which is the working speed of the upper moving wheel. For 60,1, the working speed of the moving wheel is 650rmin. 3.2.2 The braking performance test of the hydraulic retarder is added to the inertia flywheel group in the test system. In a state where the oil is not filled into the speed reducer, the power unit is started to clean the residual oil in the speed reducer. Then adjust the speed of the reducer moving wheel to 80, start the oil supply pump station, cut off the power while supplying oil to the reducer, and record the dynamic speed and dynamic speed of the reducer under the full open and half open conditions of the throttle valve respectively. Corresponding braking torque.
Adjust the speed of the reducer moving wheel to the test and record the test data.
The initial speed of the s6 brake is 120, the throttle valve is full, the sampling frequency of the data acquisition system is 50, and the throttle valve is half open compared with the full open charge. 8 is the initial speed of braking is 500rmin800rmin1 200rmin, when the throttle valve is fully open and half open, the dynamic speed of the hydraulic retarder and the braking torque change with time. It can be seen from 8 that the higher the rotational speed of the moving wheel, the larger the braking torque; with the initial braking speed, the larger the oil filling amount of the hydraulic retarder, the larger the braking torque generated, and the lowering of the rotating speed of the rotating gear of the reducer The faster it is.
200 adjusts the opening of the throttle valve with the throttle valve half-opening 8 speed and the curve of the torque with time. The liquid filling amount of the hydraulic retarder is adjusted when the throttle valve is half-opened. It is larger than the full charge of the throttle valve. It can be seen from 8 that if the initial speed of the brake is 500, the maximum braking torque when the throttle valve is half open is about 190 N, m, and the time when the rotational speed of the moving wheel is zero is about 5.3 s; when the throttle valve is fully open The maximum braking torque is about 180.1. The time when the moving wheel speed drops to zero is about 6.188. If the initial braking speed is 80, the maximum braking torque when the throttle valve is half open is about 340, and the time when the moving wheel speed drops to zero. It is 6.068; the maximum braking torque when the throttle valve is fully open is about 280N, m, and the time when the speed of the moving wheel is reduced to zero is about 7.48. If the initial speed of the brake is 1 2001, the maximum braking when the throttle is half open The torque is about 550N, m, the time when the moving wheel speed drops to zero is about 6.588; the maximum braking torque when the throttle valve is fully open is about 370. The time when the moving wheel speed drops to zero is about 7.88.
Analysis of the above data shows that, with the initial braking speed, the larger the liquid filling amount of the hydraulic retarder, the larger the braking torque generated, the faster the speed of the rotating gear of the reducer decreases, and the higher the initial braking speed, The effect is more obvious, which also shows that the hydraulic retarder uses a good braking effect at high speed and large liquid filling.
3.3 Test results Through the basic performance test and braking performance test of the hydraulic retarder completed on the test rig, the following conclusions are obtained: a. The torque coefficient of the hydraulic reducer of the test increases with the increase of the oil charge, and is full. In the state, the torque coefficient of the hydraulic retarder reaches the maximum range of 6.4, 106.6105.
Automobile technology 1 brake initial speed is 500 to throttle valve half open time sc brake initial speed is 800rmin throttle valve full open time s3 brake initial speed is 50, throttle valve full, i luxury light gasoline vehicle working condition method Correlation study of emission detection methods Peng Meichun 1 Zhou Guitian 2 Wang Wentao 1 Liu Dunxiong 2 Lin Yongjie 2 Zhao Zinc Ze 3 Xu Zhigang 3 Jiang Baicheng 31. Guangdong University of Technology; 2. Guangzhou Honda Automobile Co., Ltd.; 3. Shenzhen Huiyin Industrial Development Co., Ltd. 18352.12001 The required full working conditions, the urban working conditions in 818352.12001 and the first cycle conditions of urban working conditions have a total of five different emission testing methods. The emission characteristics of three Honda Accord vehicles under these five emission detection methods were tested and analyzed. The result is clear. The transient emission detection method can reflect the technical state of the vehicle more comprehensively than the steady-state elbow method. The transient IM195 has higher correlation with the urban working condition detection method in GB18352.12001, among which HC and NO! Above 90, the CO is also above 57.
Correlation of the main word light gasoline vehicle emission detection method 1 Look at the increasingly serious motor vehicle exhaust pollution in China, it is extremely urgent to improve the emission standards of motor vehicles. Successful foreign experience shows that in addition to implementing new vehicle emission regulations and controlling pollutant emission levels, it is more important to supervise the use of vehicle emissions and implement the detection and treatment of in-use vehicle emissions. A few days ago, the State Environmental Protection Administration proposed a series of test methods in the solicited drafts of the exhaust gas emission limits and measurement methods for vehicle-ignited engine vehicles. For example, the double-idle steady-state loading method of the gasoline vehicle, the transient condition method, the simple transient condition method, the free-acceleration method of the diesel vehicle, and the deceleration method are expected to be officially promulgated in 2005. Since this new standard contains a variety of testing methods, localities can choose to promote the use according to the actual situation, and set the local standard limits. Therefore, there is an urgent need to carry out research on the selection of new standard methods and standard limits, and provide a scientific basis for the government to systematically make decisions.
The new Ministry of Science and Technology of the Ministry of Science and Technology of the Ministry of Science and Technology of the Ministry of Science and Technology of the People's Republic of China, the Ministry of Science and Technology of the People's Republic of China, the Ministry of Science and Technology, and the application of the project. Hydraulic retarder 1 Zhu Jingchang and so on. Vehicle hydraulic transmission. Beijing National Defense Industry Press, 1982.
Power technology, 20014 Ma Wenxing. Hydraulic drive theory and design. Beijing Chemical Industry Press, the revised draft was received on August 1, 2005. , J,
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