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1、LESSON 29 CONTROL SYSTEMS (DIESEL ENGINE BRIDGE CONTROL SYSTEM) II Jimei universityFig. 9 shows the basic requirements for starting and control of a direct reversing slow speed diesel engine. Jimei universityThe basic control loop for diesel engine is of closed loop form with a two or, three-term co
2、ntroller, possibly with a load limiting device and alarm, controlling the engine speed. Jimei universityDesired value signals for engine rpm are transmitted from the bridge control position or engine room remote control position and Jimei universityand compared with the measured value signal from a
3、propeller shaft speed sensor, the difference between these two signals being the rpm deviation from the required. Jimei universityThis error signal is then used by the controller to adjust the fuel racks to return the engine speed to that required. Jimei universityElectronic, electro-pneumatic, elec
4、tro-hydraulic and pneumatic systems may be used for signal transmission and fuel rack operation. Jimei universityThe direction of rotation required is achieved by moving a lever in a horizontal slot, Jimei universitymovement to either extreme operating the valves controlling the servo-motor which po
5、sitions the cam shaft for the correct air start and fuel valve timing for the required direction of rotation. Jimei universityThe lever is then moved in a vertical slot, the initial movement actuating(操操 纵纵 、 驱驱 动动 ) the starting sequence on air andJimei universityand when a pre-set rpm has been rea
6、ched (30 r/min for example) the air is tripped(切切断断) and fuel applied.Jimei universitySubsequent(后后续续的的) movement of the lever operates a servo-mechanism which adjusts the speed setting lever on the engine and which is in turn connected to the governor. Jimei universityThe starting sequence is monit
7、ored by the interlock and check circuits shown, and a programmer(程序控制器程序控制器). Jimei universityThis allows the maximum acceleration to commensurate with(与与相相应应) safe operational requirements of the engine whilst manoeuvring but prevents engine overloading. Jimei universityIt also programmes the incre
8、ase in power when moving from Full Ahead to Full Away, guarding against excessive power demands and propeller cavitation(空空洞洞、气蚀气蚀) and critical speed slipping. Jimei universityFor crash manoeuvres(应应急急操操作作) the lever is moved from one extreme to the other, the sequence of events is then controlled
9、to braking, starting and reaching full speed (ahead or astern). Jimei universityDelays may be fitted to prevent braking air being applied until the engine speed has dropped to a pre-determined r/min to prevent excessive use of starting air and cavitation. Jimei universityAn alarm may be fitted to wa
10、rn if starting air is applied to the engine for longer than, for example, 15 seconds. Crash manoeuvre signals may cut-out the governor. Jimei universityBridge/Engine room control transfer may be carried out by the bridge-engine room telegraph(传传令令 钟钟 ) with a special bridge control segment(控制部分控制部分)
11、. Jimei universityWhen both bridge and engine room pointers are on this segment, the bridge has control of the engine, Jimei universitybut if the pointer on either telegraph is moved from this position, the engine room has control, and manoeuvring may be carried out using the engine room/bridge tele
12、graph. Jimei universityLocal manual control facilities also must be provided. Jimei universityBridge instrumentation will vary according to the desires of the ship owner and manufacturer, Jimei universitybut is required to include rpm indicator, direction of rotation indicator and starting air press
13、ure, Jimei universitywhilst for unattended machinery space vessels, an emergency stop control system independent of the bridge control system is required. Jimei universityAlso the bridge watchkeeper must be made aware of any machinery fault, that the fault is being attended to and that it has been r
14、ectified. Jimei universityThere should be two means of communication between the bridge and main control station in the machinery space, one to be independent of the main electrical power supply. Jimei universityIn some cases facilities may be provided for emergency overriding oil pressure shutdown.
15、 Jimei universityIf this facility is used, adequate warning must be given to the engine room staff. Jimei universityREADING MATERIAL A. CONTROL OF PROPULSION MACHINERY FROM THE NAVIGATING (航航行、驾驶行、驾驶) BRIDGE Jimei university1. Under all sailing conditions, including manoeuvring, the speed, direction
16、 of thrust and, if applicable, Jimei universitythe pitch of the propeller shall be fully controllable from the navigating bridge.Jimei universitya) Such remote control shall be performed by a single control device for each independent propeller, Jimei universitywith automatic performance of all asso
17、ciated services, including, where necessary, means of preventing overload of the propulsion machinery.Jimei universityb) The main propulsion machinery shall be provided with an emergency stopping device on the navigating bridge which shall be independent of the navigating bridge control system. Jime
18、i university2. Propulsion machinery order from the navigating bridge shall be indicated in the main machinery control room or at the propulsion machinery control position. Jimei university3. Remote control of the propulsion machinery shall be possible only from one locating at a time. Jimei universi
19、tyThe transfer of control between the navigating bridge and machinery spaces shall be possible only in the main machinery space or in the main machinery control room.Jimei universityThe system shall include means to prevent the propelling thrust from altering significantly when transferring control
20、from one location to another. Jimei university4. It shall be possible for all machinery essential for the safe operation of the ship to be controlled from a local position, even in the case of failure in any part of the automatic or remote control system. Jimei university5. The design of the remote
21、automatic control system shall be such that in case of its failure an alarm will be given. Jimei universityUnless the Administration considers it impracticable, the present speed and direction of thrust of the propeller shall be maintained until local control is in operation. Jimei university6. Indi
22、cators shall be fitted on the navigating bridge for:a) propeller speed and direction of rotation in the case of fixed pitch propeller; orJimei universityb) propeller speed and pitch position in the case of controllable pitch propeller.Jimei university7. The number of consecutive(连连续续 的的 ， 连连 贯贯 的的 )
23、 automatic attempts which fail to produce a start shall be limited to safeguard sufficient starting air pressure. Jimei universityAn alarm shall be provided to indicate low starting air pressure set at a level which still permits starting operations of the propulsion machinery. Jimei universityB. BR
24、IDGE CONTROL SYSTEMS (U. M. S.)Jimei universityBridge control of propulsion plant and propulsion control systems centralized in a control room are now normal provision. Jimei universitySystems provided vary to some extent to suit the particular engine requirements of the major designs, e.g. Burmeist
25、er & Wain or Doxford or MAN etc. Jimei universityAs a typical example, the standard design for Sulzer RND engine provides engine control from the wheelhouse telegraph with fully automatic direction selection, starting, speed control and safety devices. Jimei universityTheir Type SBC7 bridge console
26、and control console panels are shown on Fig. 10 and 11, these being indicative(指指示示的的) of the instrumentation involved. Jimei universityIn addition to the parts listed a non-reply telegraph(非非应应答答式式车车 钟钟 ) receiver or telegraph indicator panel is mounted adjacent to the engine emergency manoeuvering
27、 controls. Jimei universityC. ALARM SYSTEM Jimei universityAn alarm system shall be provided indicating any fault requiring attention and shall: Jimei university1. be capable of sounding an audible alarm in the main machinery control room or at the propulsion machinery control position, Jimei univer
28、sityand indicate visually each separate alarm function at a suitable positionJimei university2. have a connection to the engineers rooms and to each of the engineers cabins through a selector switch, to ensure connection to at least one of those cabins. Jimei universityAdministrations may permit equ
29、ivalent arrangementsJimei university3. activate an audible and visual alarm on the navigating bridge for any situation which requires action by or attention of the officer on watch;Jimei university4. as far as is practicable, be designed on the fail-to-safety principle; and Jimei university5. activa
30、te the engineers alarm if an alarm function has not received attention locally at limited time. Jimei universityThe alarm system shall be continuously powered and shall have an automatic change-over to a stand-by power supply in case of loss of normal power supply. Jimei universityD. AUTOMATION ON S
31、HIPS Jimei universityTypical example of automation on ships are fire detection and extinguishing systems; emergency lighting systems; Jimei universityautomatic start of standby pumps supplying lubricating oil and fuel oil to the propulsion machinery; and automatic speed reduction or stopping of prop
32、ulsion machinery when faults are detected. Jimei universityFurther improvements can be achieved in an integrated control system by incorporating digital data processing equipment-that is, a computer. Jimei universityThis remarkable machine can provide rapid and accurate supervision, analysis, record
33、ing and display of the conditions it is monitoring. Jimei universityIn so doing, it serves as an extremely valuable aid to human judgement. Jimei universityBut in some control systems the computer is arranged to make the necessary decision and take the necessary action without human intervention. Th
34、is is called direct digital control. Jimei universityIntegrated bridge-engine room control systems are now available that combine the functions of engine room monitoring and control, collision avoidance, docking and manoervering, navigation, and cargo handling. Jimei universityThese systems include
35、one or several computers for facilitating data inquisition, processing, logging and display, and for exerting some degree of direct digital control over the machinery. Jimei universityE. REMOTE CONTROL AND AUTOMATION OF LARGE ARINE DIESEL ENGINES Jimei universityThe simplest way to achieve remote co
36、ntrol of large marine diesel engines is by providing a separate manoeuvring stand beside, or in front of, the engine. Jimei universityMostly, this stand has been developed into a large desk or console, comprising all the instruments needed for manoeuvring and serving the main and auxiliary engines,
37、together with all the measuring instruments. Jimei universityFurther automation requires remote control from any place in the engine room or a special control room and, in many cases, from the bridge. Jimei universityToday automation is being developed with the purpose of relieving the operators, an
38、d especially the men on the bridge, from paying any attention to levers, hand-wheels, instruments, etc. Jimei universityHowever, in most cases a manoeuvring stand at the engine is still left for direct operation of the engine in case of emergency. Jimei universityThere are three remote control arran
39、gements in general use, (a) from engine control room to engine; (b) from bridge to engine; (c) from both bridge and engine control room to engine. Jimei universityThe remote control is pneumatic up to 3O meters and electro-pneumatic beyond this distance.Jimei universityHere is given one of the remot
40、e control types applied to large marine diesel engine. It is built on pneumatic elements with a relatively simple electronic control for fine speed adjustment. Jimei universityThe system provides automatic control of the main engine from the bridge and manual control from the control room in the eng
41、ine room. Jimei universityThe pneumatic system is most reliable; and the electronic system is simple and easily maintained. Jimei universityThe electronic system contains only three insert type units; Jimei universityone is a power unit containing a transformer and a rectifier to give 24 V dc and 11
42、5 and 200 V ac; Jimei universitythe second is a programme unit for various fine speed adjustments; and the third is an electronic control for the electric step motor. Jimei universityEven if all electronics should fail, bridge control with the pneumatic system is possible. Jimei universityWhen the o
43、fficer on the bridge moves a selector switch on the bridge console to Bridge Control, the Bridge Control on the control room telegraph lights up and an alarm sounds on the telegraph until acknowledged. Jimei universityThere are also two buttons marked Fine Setting up and Fine Setting down on the bri
44、dge console. Jimei universityWhen the ship is manoeuvred out of port and it is required to increase the ship speed from Full Ahead to service speed, the officer on watch has only to depress the Automatic Acceleration Up button for the speed to be automatically and gradually increased to the required
45、 speed within a period of about 30 minutes-but again, this period is adjustable. Jimei universityTo stop this gradual acceleration the program button Automatic Acceleration off must be depressed. Jimei universityThe same system applies in reverse when the speed must be gradually returned-for example
46、, when entering a port. Jimei universityThe following indications are provided on the bridge console: (1) tachometer, (2) starting air pressure, (3) control air pressure, (4)control lamps for: (5) bridge control, Jimei university(6) control room control, (7) manual control on engine, (8) transfer of
47、 order, (9) speed correction and (10) critical speed range. Jimei universityAlso fitted in the bridge console are an emergency stop button and control lamp and an emergency run button and control lamp. Jimei universityThere are also alarms which sound when the engine is overloaded, tripped, or fails to start, and when the starting air pressure or control air pressure is too low, or when the electric power fails. Jimei universityAs the manual telegraph is also used for the engine control, the Stand by and Finished with Engine orders are carried out by using separate buttons. Jimei university
