In recent years, in order to adapt to economic development, meet logistics needs. Road network construction and road transportation have developed by leaps and bounds. The development trend of heavy-duty and train-based road transport will be stronger, and the scale of large-horsepower and large-tonnage transportation modes will be further developed. At present, because the trains consisting of tractors and trailers have relatively low acquisition costs, good adaptability, and large carrying capacity to meet the development needs of the transportation market, they have been used more and more widely in road transportation. The heavy-duty tractor-powered car trains already account for a considerable proportion of the road freight transport vehicles, and the proportion of the traffic carried by them in the total amount of road freight transport is also more obvious. Therefore, whether the safety technical condition of the automobile train composed of heavy tractors can directly meet the running standards can directly affect the smoothness of the road, which is not only related to the successful completion of the transportation tasks undertaken by itself, but also related to social harmony. Thousands of households. As an important energy DD compressed air that ensures the braking system of heavy-duty trains can work normally, it plays a vital role in vehicle safety. Therefore, the importance of heavy-duty vehicles, especially heavy-duty trucks, in obtaining timely and effective compressed air is conceivable. 1 The meaning of compressed air to ensure safe driving and effective driving As the main vehicle of heavy-duty trains, the tractor must not only have sufficient power to drive the train, but also provide power for signal illumination for the train. Braking compressed air. 1.1 Compressed air to provide the necessary energy to ensure safe driving Currently, the braking system of heavy vehicles and their trains is mostly driven by compressed air. In practice, we will find that most of the cars and car trains that are currently on the road are four- or five-bridge cars, and quite a few are six-bridge cars. Because there are many wheels, the number of corresponding brake chambers is also large, and the compressed air consumption is inevitably large during each braking process. In mountainous areas, hills, ramps, and special road conditions, vehicles need to use brakes frequently, which consumes a lot of compressed air. At this time, if there is not enough compressed air to provide assurance, driving safety will be greatly threatened. 1.2 Compressed air provides support for the realization of automobile performance, and road transport vehicles with follow-up axles that have recently been put on the market to meet the needs of the market and customers. In particular, it is to ensure that the traction vehicle is equipped with a relatively large quasi-traction force, and a follower bridge for improving the carrying capacity of the traction vehicle. During the operation of the suspend-drop device, a certain amount of compressed air is consumed for each action. If the near air is not sufficiently compressed to drive, the suspension-drop action of the follower bridge cannot be achieved. 1.3 Compressed air makes car comfort. In addition, in order to reduce the driver's driving operation intensity and ease driving fatigue, most vehicles' clutch disengagement mechanism uses air assist separation device, which greatly reduces the driving operation intensity. If there is not enough compressed air support, it is difficult to perform gear shifting and gear shifting operations. In order to improve the driver's comfort in driving the vehicle, the driving seat of most vehicles is also provided with an air conditioning system to alleviate the fatigue during driving and steering the vehicle. This also requires the support of compressed air. In summary, in order to ensure the normal driving of the vehicle, there must be sufficient and reliable compressed air as a guarantee. 2 Current supply methods and supply and demand situation of compressed air for heavy vehicles 2.1 Current supply methods for compressed air of heavy vehicles The heavy-duty vehicles that are now operating and continuously put into operation, including the semi-trailer trains with tractors as the main vehicles, all the compressed air required Provided by an air compressor fitted to the engine. Driven by the onboard engine, the air compressor continuously pumps compressed air to the brake system. 2.2 Current supply and demand situation of compressed air for heavy vehicles In the case of good normal road conditions, the compressed air provided by the air compressor equipped with the onboard engine can basically meet the needs of driving and braking of the entire train. However, under special road conditions and road conditions (such as long-distance grading, short-distance multi-curve road sections, stop-and-go when encountering road resistance, etc.), the braking process is consumed because of the frequent use of braking operations. The amount of compressed air is very large, and at this time the speed of the vehicle is low, the engine speed is correspondingly low, and it is difficult for the brake system to obtain timely and effective air supply. At this time, the compressed air supplied by the air compressor equipped with the onboard engine is difficult to meet the requirements of vehicle operation and braking. 3 Current solutions to the problem of insufficient supply of compressed air 3.1 Current solutions to the problem of insufficient supply of compressed air Because the vehicle manufacturers are limited by the matching of engine products, it is more difficult to install a compressed air supply device on the engine. In addition, the simple installation of the air compressor, in the case of the normal operation of the vehicle, the compressed air consumption is small, and the artificial power of the engine will be formed. Therefore, in order to alleviate the shortage of compressed air supply, the driving safety is ensured, so that the driver can normally operate the vehicle. Generally, the solution of setting the gas storage tank is adopted in the design to increase the storage volume of the compressed air, and to make up for the shortage of the compressed air supply of the compressor equipped with the tractor engine. Similarly, car modification companies have many axles and wheels for their semi-trailers and trailers. Considering the large amount of compressed air for braking, in order to ensure the safety of driving, it is solved from the design to the manufacturing in order to increase the number of gas storage tanks and increase the volume of the gas storage tank. 3.2 The solution to the problem of insufficient supply of compressed air The solution of the gas storage tank is increased to increase the storage volume of compressed air to solve the problem of insufficient supply of compressed air, but the problem of insufficient supply of compressed air is suspended, and it is not fundamentally Solve the problem. The problem of insufficient supply of compressed air is solved by increasing the number of gas storage tanks and increasing the volume of gas storage, ignoring the balance between the supply of compressed air and the amount of gas used. When the vehicle is running (as described above, long slope, trailing, road resistance, etc.), the brakes need to be used frequently, because the amount of gas used is too large, and when it is not effectively supplemented for a short time, the situation can be imagined. During the use of the vehicle, we have the experience that whether it is a new car or a vehicle in use, the engine-driven air pump needs to be operated to inflate the compressed air of the brake system before the vehicle starts running. The number of gas storage tanks is large, and the gas storage volume is large, which inevitably extends the running time of the engine pumping air pressure. For in-use vehicles that have been used for a certain period of time and have a certain mileage, the engine and air compressor have produced different degrees of wear and the air supply capacity has decreased. In addition, the brake system piping and control valves and other parts are inevitably aging or the seal is not tight, resulting in leakage of compressed air. Before each start-up operation, the car needs to run the engine for a relatively long time, and pumping up the gas storage tanks. This will inevitably increase fuel consumption and increase emissions. At the same time, it will further increase the mechanical wear of the engine and the air compressor. It can be seen that the air pump equipped only by the automobile engine is used to provide compressed air, and the method of increasing the gas storage tank cannot fundamentally solve the problem of providing sufficient and reliable compressed air to meet the demand of the vehicle. 4 Solution to the shortage of compressed air supply 4.1 Several solutions to solve the problem of insufficient supply of compressed air 4.1.1 Directly modify the air compressor installed in the engine to increase the displacement of the air compressor. The displacement of the air compressor equipped with the engine is based on the ideal road conditions, the demand for compressed air in the normal driving state of the car, taking into account the impact of the power consumption of the air compressor on the engine. Therefore, increasing or changing the displacement of the air compressor will directly affect the output power of the engine. Technical solution features: easy to implement and low cost. However, it is only suitable for some conditions in which the vehicle starts and the compressed air consumption is relatively large, and does not conform to the vehicle design program. 4.1.2 Using other power sources to drive the air compressor The air compressor is driven by other power sources, which is easier to implement with the motor drive method. However, if the vehicle battery or the on-board generator is used to provide energy, an electric motor is required, and the air compressor is driven by the electric motor. Technical features: The overall structure is more complicated, and the installation location is difficult to determine due to the complexity of the vehicle model, and the cost is relatively high. 4.1.3 Installing the air compressor at the position of the gearbox power take-off The power take-off output is a power take-off position specially designed for engineering vehicles and special vehicles. The gearbox position of the transport vehicle is mostly closed due to being idle. If the air compressor is installed at the power take-off position, it is convenient to obtain the driving power and the available installation space. Because almost all models have reserved installation space at this location. Features of the technical solution: the realization is relatively easy, the cost is moderate, and the structure is relatively simple and reasonable. Based on the above schemes, the technical solution of installing the compressed air auxiliary air supply device (air compressor) at the output end of the gearbox is more reasonable and easy to implement. 4.2 Compressed air auxiliary air supply device structure and working principle 4.2.1 Auxiliary air supply device structure Compressed air auxiliary air supply device, the interface of the power take-off output of the gearbox 2 is connected, the power take-off device is installed 7. The power take-off device 7 Torque is obtained at the power take-off interface of the gearbox. The output end of the power take-off 7 is coupled to the electromagnetic clutch 8 through a coupling, and the output end of the electromagnetic clutch 8 is supplied with torque to the auxiliary air supply compressor through the coupling 9. Compression generated by the operation of the air compressor 9 The air is sent to the compressed air storage tank 3 through the air supply line 4. Install the air pressure control switch on the compressed air storage tank. 4.2.2 Working principle of the auxiliary air supply device At the interface position of the power output end of the vehicle gearbox, the power take-off force input gear b meshes with the gearbox output force output gear a. When the air pressure of the brake system is lower than 0.6 MPa, the air pressure switch installed on the energy storage tank will be in an on state, and the power of the electromagnetic clutch is turned on. Under the action of electromagnetic force, the mechanical transmission part of the electromagnetic clutch is in a combined state, so that the torque obtained by the power take-off, the electromagnetic clutch is transmitted to the air compression 1. The engine 2. The gearbox 3. The gas storage tank 4. The gas pipeline 5. The air pressure Control switch 6. Engine equipped with air compressor 7. Power take-off 8. Electromagnetic clutch 9. Auxiliary air supply air compressor a. Gearbox power output gear b. Power take-off force input gear drive air compressor operation. Compressed air is supplied to the vehicle brake system. When the air pressure of the brake system is not lower than 0.6Mpa, the air pressure switch installed on the energy storage tank will be in the off state. At this time, the power supply of the electromagnetic clutch is cut off, so that the mechanical transmission portion of the electromagnetic clutch is in a disengaged state, and the air compressor is stopped. The compressed air required for the vehicle's brake system is still provided by the air compressor fitted to the engine. During the driving process, the power take-off mechanical control mechanism can also be used as needed to select whether the auxiliary air supply device participates in the operation of the compressed air supply system. 5 The positive effect of the compressed air auxiliary air supply device The technical solution of installing the auxiliary air supply system at the output position of the transmission force. Has the following significant effects. a. The compressed air auxiliary air supply device solves the problem that the current compressed air supply of the automobile train is insufficient, jeopardizes the driving safety and affects the normal operation of the vehicle. b. The automobile production enterprise can make no major changes to the original design on the basis of the original vehicle, and only need to supplement the installation of the compressed air auxiliary air supply device on the original vehicle to meet the vehicle operation requirements. c. The compressed air auxiliary gas supply device can reduce fuel consumption and reduce exhaust gas emissions to a certain extent. It conforms to the current national industrial policy of energy conservation, consumption reduction and emission reduction. d. The fuel-saving effect of the compressed air auxiliary gas supply device is adapted to the fuel tax reform plan to be implemented. At the same time, it can effectively reduce the engine wear caused by the pumping process of the vehicle, prolong the engine life, reduce the running cost of the vehicle, and adapt to the market to cater to customers. e. The compressed air auxiliary air supply device is easy to operate and can be automatically connected or separated. Does not affect the driver's driving experience. The compressed air auxiliary air supply device is a solution proposed on the basis of long-term observation and summary of heavy vehicles, especially trains composed of tractors and semi-trailers. This method will be further enriched and verified in the future practical application process. Alloy Steel Coil,Steel Alloy Coil LIAOCHENG CHANGYI METAL MATERIAL CO., LTD. , https://www.cnsteelsheet.com