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By 袁春凤 (Tiffany)
Fatigue life prediction of rubber bushing in vehicle system
1.Response analysis of rubber bushing under random excitation The Monte Carlo method is used to simulate the random excitation spectrum.
2. The fatigue life calculation of rubber bushing under random load can calculate the maximum strain energy density of rubber bushing under different excitation by using the response characteristics of rubber bushing under engine and road excitation obtained previously. The fatigue life of rubber bushing can be calculated under different load conditions. The maximum strain energy density U = 0.5134Nmm2 and the fatigue life N = 771371 were predicted under the excitation of engine speed n = 3000r/min and class B pavement, while U = 0.6893Nmm2, N, = 146774 under the excitation of engine speed n = 3000/min and class D pavement.(Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department.)
3. The test verification of the front sub-frame module is expensive because of the fatigue test of the whole vehicle system. Now the former sub-frame module is the research object, and the calculation results are compared with the test results. The front sub-frame is installed in accordance with its layout in the vehicle, and the six points connected with the body on the sub-frame are restrained. Sinusoidal excitation is carried out at the midpoint of the rear beam, and the maximum frequency which can be reached under the condition of satisfying the amplitude of the force is taken as the test frequency. The amplitude of force is 2.45.2kN. Fatigue failure criteria of rubber bushing: 2mm crack (equivalent to 20% of tensile coefficient).
By 袁春凤 (Tiffany)
Structural form of engine suspension mount
In the design of engine mount, the purpose of mount, such as the quality of support and limited displacement, must be fully considered, and the reasonable shape must be chosen. There are three basic types of mounting: compression, shearing and tilting (see figure below).(Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department)
If the displacement of the power assembly is too large, the total power cost will be caused, or the intake and exhaust system, control mechanism, pipeline, wiring and other peripheral parts will be damaged. At the same time, the mounting cushion is easy to damage. For this reason, suspension stiffness must be limited from overhanging structure 1, plus larger displacement. For example, when a car is accelerating or turning, the inertia force generated by the power assembly may cause a greater displacement of the power assembly. In order to limit the displacement of power assembly, it is necessary to design rigid suspension, that is, large stiffness suspension cushion 2, nonlinear and variable stiffness suspension structure, in order to reduce the vibration caused by small exciting force and limit the large vibration displacement when large exciting force. For example, the engine output torque is small when the car stops idling, or when the car runs at a constant speed. At this time, the lower stiffness of the suspended cushion should be designed to effectively isolate vibration. But in the fast start, the reaction force of the driving torque is very large, which can make the power assembly produce greater vibration. In addition, when the vehicle is running on uneven road surface, with the large ups and downs of the whole vehicle, the dynamic assembly also produces great up and down inertia. At this time, the stiffness of the suspension cushion is increased, which can effectively limit the vibration and position of the power assembly. Shift
By 袁春凤 (Tiffany)
Rubber bushing is mainly used in the position of automobile front and rear suspension and other frequent vibration. It plays a vital role in the whole vehicle NVH (Noise Vibration Harshness), and it will be invalid and will affect the whole vehicle noise and driving stability. The failure mode of rubber bushing is not only its own quality control, but also its working environment is one of the key factors affecting its life. Thanks for the support of the Feilong Jiangli technical department.
Automobile suspension is a component that connects the frame (or body) with the axle (or direct and wheel). Its main functions are: D mitigates and inhibits vibration or shock caused by uneven pavement to ensure the car has good smoothness; 2 (2) rapidly attenuates the vibration of the body and axle (or wheel); 3 (3) transfer function in the wheel and frame (car) Various forces (vertical force, longitudinal force, transverse force) and moments (braking moment and reaction moment) between the body; 4) to ensure the necessary stability of the vehicle.
By Mengjuan Zhu
This power assembly mounting arrangement design uses more mature left, right engine side and transmission side three-point mounting arrangement, are rubber mounting. In the road test of NVH performance of mounting system, one measuring point (three-way sensor) is arranged on the active side (i.e. connecting engine side mounting bracket) and the passive side (i.e. connecting body side mounting bracket) of each mounting. The noise measuring points are located in the driver's right ear, the right ear of the non-left seat and the right ear of the rear left seat respectively. Set up a measuring point.
Under the condition of slow acceleration, the active and passive side brackets of the engine have obvious resonance bands around 260 Hz, and the maximum speed of the engine is about 3860 rpm.
Under the condition of slow acceleration, the sound pressure inside the vehicle has obvious peak value at about 3860rpm of the engine speed.
(Thanks to the engineers from Feilong Jiangli providing information)
Truck refrigeration system consists of four parts: compressor, condenser, expansion valve and evaporator.
transport refrigeration units
The compressor is the power of the refrigeration cycle and is driven by an electric motor to continuously rotate. It can not only extract the vapor in the evaporator in time, maintain low temperature and low pressure, but also increase the pressure and temperature of the refrigerant vapor through the compression function, creating conditions to transfer the heat of the refrigerant vapor to the external environment medium. In other words, the low-temperature and low-pressure refrigerant vapor is compressed to a high-temperature and high-pressure state, and room temperature air or water is used as a cooling medium to condense the refrigerant vapor.
The function of the compressor is to compress low-pressure steam into high-pressure steam, thereby reducing steam volume and increasing pressure. The compressor sucks the working medium vapor with lower pressure from the evaporator, and sends it to the condenser after the pressure increases. The high-pressure liquid is condensed in the condenser. After being throttled by the throttle valve, it becomes a low-pressure liquid and is sent to the evaporator. In the evaporator, it absorbs heat and evaporates into low-pressure steam, which is then sent to the compressor inlet to complete the refrigeration cycle.
The condenser is a heat exchange device that uses the ambient cooling medium (air or water) to take the heat of the high temperature and high pressure cooling steam from the cooling compressor, so that the high temperature and high pressure refrigerant vapor is cooled and condensed into a high pressure normal temperature refrigerant liquid. It is worth mentioning that in the process of transforming refrigerant vapor into refrigerant liquid, the pressure of the condenser is constant and still at high pressure.
3.Throttle element (namely expansion valve)
The high-pressure and normal-temperature refrigerant liquid is directly sent to the low-temperature scale evaporator. According to the corresponding principle of saturation pressure and saturation temperature, the pressure of the refrigerant liquid is reduced, thereby reducing the temperature of the refrigerant liquid. The high-pressure and normal-temperature refrigerant liquid passes through the throttling element of the decompression device to obtain a low-temperature and low-pressure refrigerant, which is sent to the evaporator to absorb heat and evaporate. In daily life, capillary tubes are often used as throttling elements for refrigerators and air conditioners.
The evaporator is also a heat exchange device. The low-temperature and low-pressure refrigerant liquid evaporates (boils) into steam after being throttled, absorbs the heat of the material to be cooled, reduces the temperature of the material, and achieves the purpose of freezing food. In the air conditioner, the surrounding air is cooled to cool and dehumidify the air. The lower the evaporation temperature of the refrigerant in the evaporator, the lower the temperature of the cooling substance. In the refrigerator, the evaporation temperature of the general refrigerant is adjusted to -26°C to -20°C, and in the air conditioner, it is adjusted to 5°C to -8°C.
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transport refrigeration systems
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Truck refrigeration system V450F for midtrucks from 12-28m³