外文翻譯--皮帶傳送系統(tǒng)及其牽引系統(tǒng)-文庫(kù)吧
2025-04-17 06:11 本頁(yè)面
【正文】 nected directly to the drive system reducer and are a modified configuration of a standard AC induction motor。 By inserting resistance in series with the motor’s rotor windings。 the modified motor control system controls motor torque。 For conveyor starting， resistance is placed in series with the rotor for low initial torque。 As the conveyor accelerates， the resistance is reduced slowly to maintain a constant acceleration torque。 On multipledrive systems， an external slip resistor may be left in series with the rotor windings to aid in load sharing。 The motor systems have a relatively simple design。However, the control systems for these can be highly plex， because they are based on puter control of the resistance switching。 Today， the majority of control systems are custom designed to meet a conveyor system’s particular specifications。 Wound rotor motors are appropriate for systems requiring more than 400 kW 。 DC motor DC motors， available from a fraction of thousands of kW ， are designed to deliver constant torque below base speed and constant kW above base speed to the maximum allowable revolutions per minute(r/min)， with the majority of conveyor drives, a DC shunt wound motor is used。 Wherein the motor’s rotating armature is connected externally。 The most mon technology for controlling DC drives is a SCR device， which allows for continual variablespeed operation 。 The DC drive system is mechanically simple, but can include plex customdesigned electronics to monitor and control the plete system。 This system option is expensive in parison to other softstart systems。 but it is a reliable, costeffective drive in applications in which torque,load sharing and variable speed are primary considerations。 DC motors generally are used with higherpower conveyors， including plex profile conveyors with multipledrive systems， booster tripper systems needing belt tension control and conveyors requiring a wide variablespeed range。 1． 2 Hydrokiic coupling 山東建筑大學(xué)畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 3 Hydrokiic couplings， monly referred to as fluid couplings， are posed of three basic elements。 the driven impeller, which acts as a centrifugal pump； the driving hydraulic turbine known as the runner and a casing that encloses the two power ponents。 Hydraulic fluid is pumped from the driven impeller to the driving runner, producing torque at the driven shaft。 Because circulating hydraulic fluid produces the torque and speed， no mechanical connection is required between the driving and driven shafts。 The power produced by this coupling is based on the circulated fluid’s amount and density and the torque in proportion to input speed。 Because the pumping action within the fluid coupling depends on centrifugal forces。the output speed is less than the input speed。 Referred to as slip。 this normally is between l% and 3%． Basic hydrokiic couplings are available in configurations from fractional to several thousand kW 。 Fixedfill fluid couplings。 Fixedfill fluid couplings are the most monly used softstart devices for conveyors with simpler belt profiles and limited convex/concave sections。 They are relatively simple,lowcost,reliable,maintenance free devices that provide excellent soft starting results to t
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