畢業(yè)設(shè)計英文翻譯原文.doc

英文翻譯英文原文1. General description of the SIEMAG disc brake unitThis brake unit is the electro-hydraulic control system of a gearless disc brake for winders. The brake unit operates on the exhaust principle, i.e. the braking force is generated by sets of disc springs and released by hydraulic pressure.The braking force generators with the brake shoes directly act axially on the brake disc. The braking force is generated by sets of disc springs and transmitted onto the brake shoes. The number of brake elements determines the respective braking force required.As soon as the brakes are being released, the brake shoes are lifted form the brake disc with the aid of pressure oil. During the braking, the oil flows back into the tank and the brake shoes are being pressed against the brake disc.The braking force generators type BSFG 408 are s series product supplied by the Swedish firm ASEA-Hagglunds. They have a maximum press-down force of2X7906 kN.For reasons of better system availability, the hydraulic pressure is generated by two regulating pumps that are each driven by an electric motor. Both pumps are started when the system is being switched on. Any failure of a pump will be signaled.The oil filtration is undertaken by a pressure filter6.2provided in front of the braking force generators. Furthermore, two gear pumps that are directly coupled with the regulating pumps, maintain a permanent oil cooling and filtering circuit during system operation (filter6.1and cooler14). Both filters have an electrical contamination control. The mesh size of the filters is specified by the supplier to be 10m (see TAS No.3.9.6.4). The equipment includes a controlled electrical tank heating. The fluid level in the tank is monitored as well.The service braking is done with the aid of two electrically controlled proportional pressure relief valves43.1and43.2that are hydraulically connected in series.The safety braking is done with the aid of position-controlled 4/2-way electro valves53.1、53.2、39.1、39.2、58.1、58.2、66.1，and66.2which are electrically actuated in closed-circuit connection. In the event of a safety braking, the directional control valves39.1and39.2are switched off, separating thus the pump pressure from the remaining brake releasing system(hydraulic shunt).During the safety braking, the directional control valves6.1and66.2are acting as pilot valves for the 2/2-way valves65.1and 65.2which again release the pressure relief valves64.1and64.2.The electro valves53.1and53.2operate as outlet valves according to TAS No.3.9.5.9.The mechanically controlled pressure relief valves60.1and60.2are arranged in the outlet line of these valves. They determine the residual pressures in the course of safety braking. These residual pressures (pressure stages 1 and 2) are maintained by bladder-type accumulators.The gas pressure of the respective accumulator used is monitored.The march of pressure is adjusted with the aid of mechanical skids which are adapted to the braking process desired.A hand-operated pump48is provided for assembly purposes, when the controlled main stop cocks46.1and46.2in the outlet line of the brake elements are locked.The position-controlled 4/2-way valves63and the pressure relief valves 25.1and25.2(residual pressure accumulator) are fed by a back-up power supply in open-circuit connection. The valves get open when the solenoids are energized.With the commandRELEASE BRAKE，the two residual pressure accumulators are filled through the check valves87.1and87.2.The residual pressure accumulator24.1(pressure stage 1) is connected through the 4/2-way valve86. The residual pressure accumulator24.2(pressure stage 2) is automatically connected by a change-over of the 4/2-way valve86, when the hoisting load changes accordingly.2. Functional description of the electro-hydraulic control system corresponding to the hydraulic drawing No.0905216/12.1 Method of operation of the brake unitThe braking force is the sum of pressing forces per brake shoe, reduced by the forces being generated by the oil pressure in the cylinders of the brake element.The force required for the service braking is achieved by controlling the oil pressure. Two pressure regulating valves43.1and43.2, each being fitted with separate control electronics and function control, are connected in series, permitting thus a stepless adjustment of the valves between a minimum and a maximum pressure. In the case of failure of one brake is applied when the spring forces press the brake shoes against the brake disc without counterpressure. The brake is released when the pressure oil in the cylinders of the brake elements reduces the spring forces to zero and the brake shoes are lifted the brake disc.The brake releasing pressure is generated through the pressure-controlled pumps1.1and1.2which are driven by electric motors3.1and3.2. The pressure regulating valves of the pumps are adjusted in such a way that, as soon as the brake releasing pressure has been reached, the pumps reduce the flow rate from the maximum value to the quantity required for maintaining the releasing the pressure. This means in other words that the pumps only deliver the quantity of oil that is demanded to replace any oil losses from leakage and to maintain the pressure adjusted on the pressure regulating valves43.1and43.2.When starting the safety braking, the circuit of the electro-hydraulic brake control system (including pump motors) is cut off. The 4/2-way valves 53.1，53.2,39.1and39.2are thus de-energized and the pump circuit is separated form the brake elements and the pressure accumulators24. The service brake valves43.1and43.2remain energized through a back-up current supply. The residual pressure is as high as to ensure the winder retardation being below the rope slip limit.The hand-operated pump48is only connected for the start-up operation and stored separately.2.2 Operating states2.2.1 Starting the systemThe winder is at standstill and the brake applied. The control voltage and the voltage for the pump motors3.1and3.2is available. The electrical monitoring system signals the system to be trouble-free and all preconditions for starting the pumps1.1and1.2fulfilled (please see also item 2.3.1), which means that the safety circuit is closed as well.The 4/2-way valves39.1and39.2are energized by starting the pump motors3.1and3.2,thus opening the cross section between pumps and brake elements. The safety brake valves53.1、53.2、58.1、58.2、66.1and66.2close.The pumps1.1and1.2are now connected through the pressure regulating valves43.1and43.2with the brake elements. The coils of these valves are de-energized, i.e. the valves are open, permitting the oil to return without pressure form the pumps1.1and1.2through the pressure regulating valves into the tank.2.2.2 Releasing the service brakeWith the commandRELEASE BRAKE, the coils of the pressure regulating valves43.1and43.2are fed with the maximum valve of regulable current, and the valves retain the maximum releasing pressure adjusted. The pumps1.1and1.2thus feed the oil through the valves39.1and39.2to the brake element. The accumulators for the residual pressure24.1and24.2are also filled through the operating pumps. The brake elements are released as soon as the maximum releasing pressure has been reached. The pressure-controlled pumps then reduce the flow rate to the quantity required for compensating all oil loses form leakage. The releasing pressure is maintained by the pressure regulating valves43.1and43.2.The pressure switches34.1/34.2monitor the filling of the bladder-type accumulators for residual pressure24.1/24.2.With this operating state, the valves53.1and53.2are closed and the outlets of the hydraulic safety circuit thus locked.2.2.3 Service brakingDuring the service braking, the pressure regulating valves43.1and43.2are steplessly controlled. This reduces the releasing pressure in conformity with the position of the brake lever. The oil displaced form the brake elements as well as the excess oil form the pumps1.1and1.2flows back through the pressure regulating valves43.1and43.2into the tank.These proportional pressure regulating valves comprise a pilot control valve and a main valve. They are operated by parallel control of the pilot control valves with the main valves connected in series.This means in other words that both proportional pressure regulating valves are always active in the pilot control circuit. However, the main pressure regulating function is always fulfilled by that valve which is nearer to the pressure source. Only in the event of a failure this function is performed by the subsequent valve.The power supply to the control electronics of each regulating valve is additionally backed up by a battery ensuring, in the event of a total power failure or wire brakeage, that at least one regulating valve remains operative.The buffered voltage supplies are monitored for a failure of the buffering in the electrical and electronical circuits of the brake control system.2.2.4 Safety brakingAs soon as the safety circuit is actuated, the pump motors3.1and3.2and the entire electrical control system, except the control of the service brake regulating valves, are de-energized.The oil draining pressure is released through the pressure relief valves 64.1and64.2by de-energizing the solenoid valves66.1and66.2. The releasing pressure in the brake elements and in the conduits is thus rapidly reduced to that value at which the brake shoes touch the brake discs without pressing force.The de-energized valves39.1and39.2(hydraulic shunt) isolate the pumps1.1and1.2form the brake elements and, at the same time, connect the brake elements with the residual pressure accumulator 24.1and24.2.The hydraulic pressure is further reduced the residual pressure lever through the directional control valves53.1and53.2, the throttling valves 56.1and56.2as well as the cam-controlled pressure relief valves60.1and60.2connected in parallel.The opening time of the above valves determines the threshold time, it can be adjusted through the throttling valves59.1and59.2in a range of 0.2 and 1.0 s. The minimum pressure valve of the open valves60.1and60.2is equivalent to the residual pressure valve and is limited by the final position of the mechanical cam plate.The residual pressure valve is reached after a prolon-gated threshold time of approx.0.1s.For a fine adjustment of the threshold curve and as an additional safety measure ,two throttling valves57are provided for the respective residual pressure value. These components permit the pressure reduction characteristic (braking curve) to be variably adjusted (depending on requirements) and reproduced at any time.The capacity of the residual pressure accumulator is adapted to the maximum braking time of the winder, under consideration of the opening cross sections of the valves 57and of the leakage rate of all valves. The time of maintaining residual pressure is abt.50% longer than the maximum braking time.When the winder comes to a standstill, a time element is started. After abt.2s, the valve63is opened by a starting pulse and the residual pressure reduced to zero. At the same time, the residual pressure accumulator not needed is discharged through the pressure relief valve25.1or25.2(the valve is energized for a shor