Design of EMU Automatic Transmission Gearbox

1.Overview

The automatic transmission gearbox of a high-speed EMU is one of the core components for power transmission between the traction motor and the wheelset. It plays a very important role in the power transmission and safe operation of the high-speed EMU. This article mainly introduces the design reference factors, structure and operating parameters of the gearbox of the EMU. 1. Introduction.

In recent years, with the continuous development of high-speed EMU trains, high-speed EMU trains have become one of the main means of transportation for people. To build and improve the technical standard system of China’s EMUs and implement the “going global” strategy requirements, the China Railway Corporation, based on the development needs of China’s railways, has decided to develop China’s standard EMUs with independent intellectual property rights. The development of China’s standard EMUs is of great significance for maintaining the sustainable development of China’s high-speed railways, promoting the industrialization of independent innovation achievements in high-speed rail equipment, and comprehensively and systematically mastering the core technologies of high-speed railway EMUs and key equipment.

2. Automatic Transmission Gearbox design factors

The drive device should be able to safely and reliably transfer traction force and braking force. It should reasonably select the suspension method between the motor, gearbox and the frame, avoid resonance, and the bogie structure should be able to effectively decouple the wheel-rail impact from the traction motor and other components. The gearbox is used to reduce the high rotational speed of the motor to the required rotational speed of the wheels. The gearbox housing should have sufficient strength and be able to resist the impact of gravel. The gearbox should be equipped with temperature sensors and circuit breakers, and the bearings of the large and small gears should be monitored. The gearbox should adopt a labyrinth seal design to prevent oil leakage and be equipped with an oil level inspection device to determine whether oil replenishment is needed through it.

3.Automatic Transmission Gearbox composition

The gearbox composition is a key component for power transmission in high-speed trains. The service reliability of the gearbox will directly affect the operation safety of the train and the life and property safety of passengers. The gearbox composition includes the gearbox housing, gears, bearings, couplings, suspension devices, sealing components, fasteners, etc. The gearbox composition is a complex elastic mechanical system, with the characteristics of high rotational speed and complex forces. The gearbox directly withstands the vibration excitation caused by track irregularities and also bears the vibration excitation caused by transmission errors and time-varying meshing in the system. The dynamic response is relatively complex, and various parametric resonance forms, such as superharmonic resonance and subharmonic resonance, often occur at specific frequency excitation, which will have adverse effects on the service of the gear transmission system and even lead to resonance failure of the system. The composition diagram of the gearbox is shown in Figure 1.

1 – derrick, 2 – coupling, 3 – gear mesh window, 4 – temperature sensor, 5 – fuse, 6 – split type aluminum alloy enclosure, 7 – plate with the stone

4. Automatic Transmission Gearbox selection for high-speed EMU

There are two types of gearboxes for high-speed EMUs: integral type and split type. Japanese vehicles generally use the integral type, while European vehicles generally use the split type. The integral type has better strength and stiffness, but the assembly process is complex and requires placing the large gear inside the gearbox first, then completing the pressing of the large gear and the axle within the gearbox. The assembly process requires precise and strict requirements; the split type has a simpler assembly process and is conducive to ensuring the assembly quality of the gearbox. When designing, the strength and stiffness of the box body should be fully considered, and the box body is processed through assembly and grouping, which requires high requirements for fixtures and processing techniques.

5. Structure of the split-type Automatic Transmission gearbox

The split-type gearbox is connected to the frame through vertical suspensions, uses a pie-shaped rubber component, and the gearbox is grounded and returns current. Real-time temperature sensors and circuit breakers are used to monitor the temperature of the gearbox simultaneously. The gearbox is a parallel-axis single-stage cylindrical helical gear reduction box, mainly consisting of the gearbox box body, traction gear, bearings, support device, lubrication system, sealing system, grounding return device, sensors, fasteners and other accessories. There are three sets of bearings for the small gear shaft: two sets of cylindrical roller bearings and one set of four-point contact ball bearings. The cylindrical bearings bear radial loads, while the ball bearings bear axial loads. Two sets of tapered bearings are arranged on both sides of the large gear to bear axial and radial loads; the coupling is a two-part structure, with one half of the coupling connected to the small gear shaft through interference fit and the other half connected to the motor shaft through interference fit; the large gear and the axle are in interference fit; the large and small gears are a pair of straight cylindrical helical gear meshing pairs. The gearbox box body is made of cast aluminum alloy.

The gearbox box body consists of the upper box body and the lower box body. The splitting surface of the box body is located at the center of the two shafts and has a certain angle with the horizontal plane. The suspension installation seat of the gearbox is set at the front end of the upper box body, and the upper box body also has a temperature sensor installation seat and a gear meshing observation hole; the lower box body is equipped with an oil level observation hole, an oil filling hole, an oil drain hole, and a protective plate installation seat. To enhance the rigidity of the box body, strengthening is provided on the sides of the upper and lower box bodies, and strengthening ribs and oil collection grooves are set on the inner walls of the upper and lower box bodies. The specific internal structure is shown in Figure 2.

Supplier

Luoyang Fonyo Heavy Industries Co., Ltd,founded in 1998,is a manufacturer in cast railway parts.Our factory covers an area of 72,600㎡, with more than 300 employees, 32 technicians, including 5 senior engineers, 11 assistant engineers, and 16 technicians.Our production capacity is 30,000 tons per year. Currently, we mainly produce casting, machining, and assembly for locomotive,railcar,high-speed trains, mining equipment,wind power,etc.Our products have been exported to Russia, the United States, Germany, Argentina, Japan, France, South Africa, Italy and other countries.
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