GB2042437A

GB2042437A - Explosion-proof diesel locomotive

Info

Publication number: GB2042437A
Application number: GB7941482A
Authority: GB
Original assignee: GANZ MAVAG MOZDONY VAGON
Current assignee: GANZ MAVAG MOZDONY VAGON
Priority date: 1979-01-20
Filing date: 1979-11-30
Publication date: 1980-09-24
Also published as: JPS5599459A; DE2952796A1; PL221369A1; FR2446751B1; FR2446751A1; GB2042437B; PL123110B1; HU180763B

Abstract

In an explosion-proof diesel locomotive, the controlling, monitoring, protecting and indicating system has a pneumatic two-way selector switch (4) for setting between "EXPLOSION PROOF" and "NORMAL" mode of operation and the switch position is displayed on the outside of the locomotive. For this purpose, the actual position of the selector switch (4) for changing the mode of operation is conveyed to a signal display board with indicators mounted on each side of the locomotive which is well readable from a distance, and to the instrument panel in the driver's cabin. When in the "explosion proof" mode, the locomotive is less likely to initiate an explosion during travel through an environment which is liable to explosions. <IMAGE>

Description

SPECIFICATION Explosion-proof diesel locomotive with a selector switch for changing and signalling the mode of operation thereof The invention concerns an explosion-proof diesel locomotive provided with apparatus for controlling, monitoring, protecting and signalling its operation and incorporating both a two-way or two-position selector switch for changing over the mode of operation between a so-called "explosion proof" and a so-called "normal" setting, and an indicator unit for indicating the selected mode of operation.

Diesel locomotives suitable for operating in environments liable to explosion hazard are designed to comply with specific safety regulations. In view of the stringency of these regulations on the one hand, and the characteristically explosion-prone manner of electrical power transmission on the other hand, in practice only the so-called diesel-hydraulic locomotives can be regarded as explosion-proof.

To satisfy the above-mentioned regulations, current locomotive manufacturing practice consists in converting, adapting or modifying pre-existing sub-assembly units or even already available completed locomotives. This however, leads to the impairment of the design parameters of these units or locomotives and to the narrowing of their field of application, thus down-grading this category of locomotives. The problems caused by the introduction of the restrictions cannot be solved by using a locomotive specially designed for explosion-proof operation, if this locomotive operates in an explosion-risk-free environment.

Due to the limitations imposed by the explosion-proof design, such locomotives can only utilise a relatively small portion of the total operating time for traction compraed with the nominal capacity of installed power units.

Their utilisation coefficient is therefore low and their operation is uneconomic.

Due to the safety regulations, the explosionproof diesel locomotives known hitherto have always been provided with a discrete changeover switch with the aid of which the locomotive driver shuts an air compressor down.

According to the present state of art, the satisfactory operation of an air compressor complying with the safety regulations cannot be ensured at all, or only with considerable disadvantages. Generally, the attention of the locomotive driver is drawn to the necessity of switching over by a warning note on a notice board.

Due to the rapid development of the industrial technolical operations and plants liable to explosion hazard as well as the growing prominence of hydrocarbon-based energy carriers and distinctly non-civilian character of certain industrial plants, during the approximately 40 years' history of the development of diesel locomotives the question of operational economy has been overshadowed by the pressure to modernise the standards of protection against explosion. This philosophy could therefore not lead to generally economic solutions. Also, the development has been impeded by the peculiar circumstances that the manufacturing of explosion-proof tractionvehicles belongs to the sphere of interest of relatively young industries (petroleum, chemical and ordnance industries) rather than to the railway industry with its century-old experience in the field of traction.It is indicative of the unsettled conditions in the field of safety regulations technical requirements and standards and the lack of technical publications and of stimulating initiatives by the authorities that although e.g. the highly regarded and widely accepted technical guidelines for explosion-proof locomotives issued by the Physikalische Technische Bundesanstalt (PTB) in Braunschweig (FRG) in co-operation with the Research Institute for Accident Prevention in Hamburg, (FRG), nevertheless, in its publication "PTB-Mitteilungen" 1965, No. 3, pages 247-249 (in paragraph 2.8 of Chapter I) was compelled to draw attention-amongst other important measures-to locomotive-drivers' warning boards and instruction manuals.This relatively primitive level of safety technology means that the protection against explosion hazard in many cases of large industrial plants depends on the conscientiousness of and care of the driver of the vehicle and on the standard of training of the instructors. In other words: the folly of a careless locomotive driver, if not detected in time, can bring disaster upon masses of innocent workers of an industrial estate.

The described primitive level of safety technology and the decisive role of the subjective element involve the risk of grave danger, because: -if the locomotive driver travelling into a zone classified as liable to explosion hazard forgets to carry out the prescribed switch over the operation of the locomotive may cause fire or explosion; since the disconnection of the air compressor is unavoidable in an environment with explosion hazard, the locomotive has no replacement supply of compressed air and is liable to consume the compressed air stored in the air reservoir down to the permitted lower limit of the pressure. The maximum duration of locomotive operation with a disconnected air compressor then depends on the capacity of the compressed air reservoir vessel and on the conditions of operation.In order to replenish the air reservoir, the locomotive is compelled to leave the area with explosion-hazard in good time. If the locomotive driver fails to do this, the locomotive is put out of action. In such a case a separate traction-vehicle is required to tow the locomotive into an explo sion-free area where its diesel engine can be restarted and the air storage reservoir vessel replenished. Such restrictions and inconveniences may tempt the locomotive driver to operate the air compressor also in forbidden conditions if according to his own judgement the explosion hazard is moderate and nobody will find out the forbidden operation.This sort of danger is increased by the circumstances that due to the physical properties of explosive gases and vapours, the locomotive driver can gain the "experience" that operating the air compressor is not dangerous because he does not know the fact that gas-air or vapourair mixtures, which at atmospheric pressure and in low concentration are not dangerous, become highly explosive and hazardous at the pressure of the main air reservoir. The explosion can happen even after leaving the danger zone.

The invention aims to improve the standards and the economy of operation of explosion-proof diesel locomotives to eliminate the described drawbacks of the known arrangements and to provide controlling, monitoring or inspecting protective and signalling or indicating devices with the aid of which the requirements regarding protection against explosion may be met more effectively, the efficiency of utilisation of the built-in power capacity of the locomotive may be improved, the responsible task of the locomotive driver may be made considerably easier and his work rendered publicly controllable, thus substantially reducing the probability of the dire consequences of an explosion caused by a careless driver.

The invention is based on the discovery that the above aim may be achieved if a (preferably two-way) change-over switch is built into the system of control monitoring or inspection and protection and signalling or indicating units, which switch is settable between two switching positions "EXPLOSION-PROOF" ("Rb") and "NORMAL" ("N"). In the former mode setting, all correlated operations and connections are carried out and simultaneously all unnecessary (e.g. because of explosion hazard) operations and connections are cut out; in the latter setting, where the environment is not classified as liable to explosion hazard, all the restrictive, interlocking etc.

protective measures assigned to the previous mode of operation are simultaneously cancelled and at the same time all other operations and connections are established to the full utilisability of the locomotive.

This novel discovery on which the invention is based also remedies by suitable technical measures the dangerous situation in which the life and safety of any chance crowds of operators working in an environment liable to explosion-hazard and the material safety of large industrial plants depend on the fail-safe working and disciplined responsible attitude of one locomotive driver.

The technical problem to be solved to achieve the objective of the invention is to gather all functions of control, inspection or monitoring protection and signalling or indication in each of the two possible modes of operation into a respective independent, closed sub-system and to integrate the two sub-systems into one unified system which can be controlled by the selector switch for the mode change-over in a simple and reliable way.Since the present state of art does not make it possible for some reliable instrument to predict in time the existence of an actual or potential explosion hazard and to intervene in time to avoid such hazards, provision has been made for a public and external monitoring and remote control of the decisive element of the conduct of the locomotive driver namely the position setting of "Rb" or "N" of the mode selector switch, by means of a suitabte information transmission path or chain and signalling apparatus.

A preferred embodiment of the invention for solving this task is described purely by way of example with reference to the accompanying drawings, wherein: Figure 1 is a block diagram of the system of the control, inspection or monitoring protection and signalling or indication of an explosion-proof diesel locomotive provided with a mode selector switch for the change of the mode of operation according to the invention; Figure 2 is a kinematic schema of the signalling mechanism for indicating the mode of operation according to the invention; Figure 3 shows the arrangement of the signal apparatus according to the invention mounted on the locomotive; and Figure 4 illustrates the two positions (4a, 4b) of the indicator disc of the aforesaid signal apparatus according to the invention.

The system diagram of Fig. 1 shows the fundamental connections and arrangements.

Since a pneumatic power source was selected for the reliable and explosion-proof operation, to actuate the functions of the two modes of operation "Rb" and "N" respectively an air compressor 1 and an air reservoir vessel 2 fitted with a pressure reducing/regulating valve 2a are required. The main starter switch 3 is also a pneumatic switch of customary design which is followed by an expediently two-way pneumatic mode switch 4 for the switch-over of the mode of operation. Depending on the setting or switching position of the switch 4 either "EXPLOSION PROOF" ("Rb") or the "NORMAL ("N") mode of operation is established.

In Fig. 1, in accordance with a pneumatically operated system, the blocks 5a, 5b, 6. .25, 26 designate individual controlling, inspecting or monitoring, protecting and indicating or signalling functions.

The continuous lines indicate individual air ducts and effects (commands) conveyed to the blocks, while the broken lines designate the individual air flow paths and effects (commands) established when the related protective installations or units are activated. Where this is not self-evident, the direction(s) of flow or of the effects or commands is/are indicated by an arrow.

In the case of a multistage variable speed type of principal power transmission is employed, the mode-change selector switch system performs this function by exclusion of the first gear or speed stage, because of the possibility of wheel spin caused by the large upsurge in the starting power of traction leading to an explosion hazard; and further, the third and possibly higher gears or stages of speed may be excluded as being unnecessary for shunting, so that in fact only one possible mode of operation results. The installations used for "EXPLOSION-PROOF" operation are expediently constructed so that they can take up without damage mechanical and thermal stresses larger than those arising in the "NORMAL" mode of operation.For instance, the device for protection against exhaust gase temperature is actuated at a temperature of 180 in the "Rb" mode while in the "N" mode the device may be exposed to 480"C.

The control, inspection, protection and signalling systems of a standard diesel-hydraulic haulage locomotive must be able to perform the following functions (using the reference numbers in Fig. 1): 7-starting the diesel engine 1 9-r.p.m. control of the diesel engine by intervention in the following cases: 8cooling water too cold 9'cooling water too hot, 10lubricating oil too hot, 1 l--oil of driving mechanism too hot, 1 4-manual shut-down of diesel engine 20-shut-down of diesel engine by triggered intervention (by shutting off the suction pipeline) in the case of a:: 1 5-lack or absence of cooling water, 21--control of the hydraulic drive mechanism 22--operation of sand spinkler, 24---operation of horn, 25--control of idling of air compressor 26flow air supply" indication.

In an explosion-proof locomotive the following new functions are added or some of the functions are modified: 7-interlock of the starting-up of the diesel engine, 19speed control of diesel engine by inter vention in case of: 12 exhaust gas too hot 1 3-lack of exhaust gas cooling water 14-manual shut-down of diesel engine 20 shut-down of diesel engine triggered by intervention (by shutting off the suction pipe line) in case of:: 1 6-low r.p.m. of diesel engine 1 7-low speed of diesel engine 18--excessively high r.p.m. of diesel engine 21--control of hydraulic drive mechanism 23--cooling water injection into exhaust pipe 25contrnl of idling of air compressor 26-' 'low air supply" indication.

The entire system can be disabled by the main starter switch 3 for switching the air supply on or off. After this switch 3, the pipe line branches into two. One branch leads directly to the various devices whilst the other is connected to or disconnected from the air supply by the mode selector switch 4 for changing the mode of operation. The two positions of this are of paramount importance from the point of view of protection against explosion. If the selector switch 4 is in "EP" ("Rb") position, all interlocks, restrictions etc.

are activated. It is expedient to make this setting of the switch 4 (the conduct of the locomotive driver) externally visible. To this end, special optical signalling/indicating devices 5a, 5b are arranged on the two sides of the locomotive in addition to an indicator arranged on the instrument panel 6 (See Fig.

3) in the driver's cabin. These signalling devices are desiged to indicate the same fact unambiguously, see Figs. 4a and 4b.

The signal board 37 for indicating the mode of operation is designed in such a way that it can give unambiguous readings even from relatively great distances and in the case of failure, full operational safety is not impaired.

In order to achieve this, the indication for the "NORMAL" mode of operation appears not only when it is in good working order and the selector switch 4 is in fact in the "NORMAL" position, but also in the case of a break-down.

Thus the mechanism illustrated in Fig. 2 is designed in such a way that the indication is automatically reset to "NORMAL" if an operating problem, breakdown etc. occurs e.g. if due to a rupture in a pipeline, there is no pressure in the branch pipeline "Rb". For this purpose, the indicator device 5a, 5b is provided with an air cylinder 32 coupled on one side to the compressed air supply (31). Its basic position is secured by a restoring spring 33. A piston rod 34 is connected via bearings 36 to the crank of a crankshaft 35 whereby it can perform a well-defined angular displacement along an arc corresponding to the length of the crank arm and the stroke of the piston.

The parameters are selected in such a way that the angular displacement generated is approximately 60'. This is required for the particular design of the signal board 37 (see Figs. 2 and 4 as an example) which is in the form of a disc divided into six identically dimensioned circular segments of 60 , with two sets of three segments each, the segments of each set being out of contact with each other, and the segments of one set being coloured differently from the segments of the other set to correspond to the two forms of the signal. The signal board 37 mounted on the side of the locomotive is housed in a case with a trefoil-shaped opening.

The described mechanism has two indications (see Fig. 4): if there is no pressure in the air cylinder 32, i.e. its basic position is secured by the spring 33, the contrasting colour with warning effect is visible in such a way that the segments alternate with the general colour of the locomotive (Fig. 4a) whereas under proper air pressure the disc turns by approximately 60 and all 6 circular ring segments show identical colours. The indications could, however, be different depending on the possibly different safety regulations and requirements. By means of the described technique, the explosion-proof diesel locomotive can be advantageously (quickly and safely) converted into a fully utilised standard haulage locomotive and vice versa. The change-over by means of a simple selector switch for changing the mode of operation according to the invention not only ensures better economy regarding the utilisation of a given locomotive for traction but also considerably eases the burden of the locomotive driver in carrying out his responsible duty thus further improving the protection of the locomotive operations against explosion hazard. The well-proven two-way pneumatic se lector switch chosen for the change over of the mode of operation is very simple and works reliably. The optical indicating device embodied in the invention consists of simple elements by conveying information to the sur roundings, and by virtue of the disciplining influence on the locomotive driver there re sults a substantially improved safety standard, although of course it cannot fully eliminate the subjective element.

Claims

1. Explosion-proof diesel locomotive com prising a compressor for compressing a gase ous medium, a reservoir vessel for said medium fitted with a pressure controlling valve, a main starter switch and controlling, inspecting or monitoring protecting and indi cating or signalling devices and a mode selec tor switch inserted after (downstream of) the main starter switch settable for enabling all necessary operations and connections for one of an "EXPLOSION PROOF" or a "NOR MAL" mode of operation while simultaneously disabling all the operations and connections of the unselected mode.

2. An explosion-proof diesel locomotive according to claim 1 wherein the selector switch is a pneumatic two-way switch.

3. A selector switch assembly for a locomotive according to claim 1, wherein the mode selector switch according to claim 1 is connected by way of pneumatic and mechanical transmission elements to a two-position operating signal display board fixed to the external side of the locomotive to indicate any one of the two said alternative modes of operation as well as an instrument panel located in the locomotive driver's cabin.

4. An explosion proof diesel locomotive according to claim 1 or a switch according to claim 3, substantially as herein described with reference to and as shown in the accompanying drawings.