How does an electric power steering motor and gearbox work?

Analysis of the Working Principle and Technology of the Motor and Gearbox in Rail Vehicles

Overview of the motor and the gearbox

As the core vehicle of modern rail transit, the design and performance of the power system of the rail vehicle are directly related to operational efficiency and safety. The power steering motor and the gearbox, as key components for power transmission, achieve energy conversion and power distribution through precise coordination. This article will systematically analyze the operation logic of the electric motor and gearbox of the rail vehicle from three dimensions: working principle, technical characteristics and collaborative mechanism.

Motor: conversion of electrical energy to mechanical energy hub rail car motor core task is to convert electrical energy efficiently into mechanical energy. Its power source is usually obtained by obtaining high voltage electricity (such as 1500V DC or 25kV AC) from the catenary or the third rail through the pantograph or collector shoe and then adjusting the voltage through the on-board transformer and inverter to drive the traction motor to work. 68 Take the three-phase AC asynchronous motor as an example. Its working principle is based on electromagnetic induction: when the stator winding is energized, it generates a rotating magnetic field, which cuts the rotor bars to form an induced current and then generates torque to drive the wheel to rotate.

(1)Technical features: high speed, through variable frequency (VF) control technology, the motor can realize step-less speed regulation of 0-100% speed range to meet the needs of rail cars’ frequent start-stop and variable speed.

 (2)Regenerative braking: when it is slow or downhill, the motor can be converted to the generator model, which will give feedback to the power grid, and the kinetic energy efficiency can reach 30%.

(3)Environmental adaptability: the IP65 protection class design ensures stable operation in moist, dust and another harsh environment. With a new type rack car as an example, the motor outputs high torque on steep slope road (such as 30% under the slope should be up to 200 kn m.), while in a flat road needs to switch to the high-speed mode (more than 80 km per hour), the motor of high power density and thermal management requirements.

Gearbox: the core of the power distribution and transmission ratio regulating the function of the gearbox is regulating motor output speed and torque, matching the power demand under different working conditions. The gearboxes of rail vehicles are mainly divided into three types: mechanical, hydraulic transmission and continuously variable transmission. Their design needs to take into account reliability, efficiency and maintenance convenience.

(1)Mechanical transmission structure (MT/AMT) principle: by gear set a fixed ratio. For instance, a dual-speed transmission uses a low-speed gear (with a gear ratio of 1:5) to handle uphill driving, while a high-speed gear (1:1) is suitable for flat road driving.

(2)Application scenarios: overloaded freight rail cars commonly use this kind of structure. The transmission efficiency can reach 98%, but the shift shock needs to depend on the electronic control clutch buffer.

Hydraulic automatic transmission (AT)

The core technology, the hydraulic torque converter, through the oil transfer of the power, cooperates with the planetary gear set to achieve a smooth shift. For example, the AT transmission of a certain model of orbital vehicle contains 3 sets of planetary gears, which can provide 6 forward gears, and the transmission ratio covers 2.5:1 to 0.6:1.

 Advantage: without the mechanical clutch, it reduces power interruption, which is especially suitable for frequent start-stop urban rail vehicles. Stepless transmission (CVT) innovative design: the steel belt combined with a conical wheel, by cone wheel spacing ratio continuous change. For example, the CVT system of a certain cog rail vehicle can dynamically adjust the transmission ratio (0.5-5.0) during driving, keeping the motor always in the high-efficiency speed range and reducing energy consumption by 15%. Challenge: steel band limit torque (such as 4000 n · m) is easy to slip and needs to cooperate with hydraulic clamping to increase friction.

Motor and transmission of coordinated control of modern power systems for rail vehicles through the intelligent control unit to realize the depth of the motors and gearboxes. For example, a high-speed emu adopted “traction – brake – drive” integration control system, its working process is as follows: data acquisition, real-time sensor monitoring parameters such as speed, slope, and load;

Decision-making operation: the control unit based on the default algorithm such as fuzzy PID calculation target velocity ratio and motor output power; Adjust the transmission gear execution feedback: electric hydraulic draw stem, at the same time-frequency converter to adjust motor speed, error control within + / – 2%. Typical case: in the rack in the power system, motor and transmission to realize dynamic switching. When the vehicle enters the cogged rail section with a 30% slope, the control system increases the transmission ratio to 5:1 and amplifies the motor torque to the peak. On straight and adhered sections, the transmission ratio drops to 0.8:1, and the vehicle speed increases to 120km/h. The entire process can complete the mode switch without stopping.

Technology development and future trends of lightweight material

Aluminum alloy and carbon fiber composite shell weight 40%, while increasing the cooling efficiency. Intelligent diagnosis: embedded sensors, such as vibration frequency 0.5-10 KHZ) combined with AI algorithms, realize transmission wear warning and life prediction. Hybrid: fuel battery and supercapacitor hybrid system can reduce the dependence on catenary and apply to section expansion without electricity. Railcar motor and transmission work is essentially a convert electrical energy efficiently to adapt to the complex working conditions of mechanical energy. With the advancement of materials science and intelligent control technology, future power systems will develop towards higher efficiency and lower maintenance costs, providing core support for the greening and intelligence of rail transit.

Supplier

Luoyang Fenyo 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.

Contact:Cathy Xu
Email:sales@railwaypart.com
Mobile:008615515321683