GB2225302A

GB2225302A - Electrical current pick-up arrangement

Info

Publication number: GB2225302A
Application number: GB8827430A
Authority: GB
Inventors: David Frederick Spriggs
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1988-11-24
Filing date: 1988-11-24
Publication date: 1990-05-30
Anticipated expiration: 2008-11-24
Also published as: AU4551189A; ZA898275B; DE8913099U1; DE3936895A1; GB8827430D0; GB2225302B

Description

' t n, ^ t' 1 Electrical Current Pick-up Arrangement 1 1 1 ilp CASE 4933

This invention relates to an electrical current pick-up arrangemnt of the kind ccmprising a longitudinally extending bus-bar and a co-operative moveable electrical pick-up member.

Electrically powered vehicles of the trolley system type, ie those which do not rely on an internal power source, use some form of pantograph or collector to pick up electrical current from either an overhead wire or a conductor which is laid along side the path of the vehicle. The most usual form of pick-up is the overhead system where a flexible pantograph rides along the wire, either with a conductive grooved roller which engages with the wire on the end of a pantograph arm or on a pantograph arrangement which has a conductive bar which engages with the wire. This latter form of pantograph allows certain movement of the vehicle transverse to the wire without there being the risk of loss of electrical contact.

With the single arm type of pick-up there is the risk that if the vehicle moves too far frem a prescribed path,, contact with the wire will be lost.

Generally overhead wires are placed in areas where there is little risk to personnel frcm contact with the wire. This is usually because the wires are suspended high above a track or a path along which a vehicle will progress and out of reach of personnel in normal circumstances. However, in restricted areas, such as in tunnels, there is not always the height to allow the personnel moving under the wire to be safely positioned without the risk of flash-over or of inadvertent touching of the wire. In order to avoid and minimise this risk, it has been proposed to enclose the wire in a protective housing. The housing itself has to be of an insulating material and has to allow access to the conductor. In order to minimise even further the risk to personnel, it is preferred that the conductor is so recessed within the housing that it is finger safe and cannot be contacted inadvertently by people touching the housing. It is one object of the present invention to provide an improved form of pick-up arrangement which minimises the risk of the conductor being touched by probing fingers.

Electrical overhead conductor arrangements can be either alternating current or direct current transmission systems. The alternating current systemi although useful for high voltage transmission and a reduction in electrical losses, does not give such a good traction characteristic owing to the nature of the motors which have to be used. Therefore a direct current system is best for traction purposes as is well-known and this may either rely on an earth return or it may be necessary to provide two conductors. If two conductors are used they clearly have to be insulated tatisfactorily frcm each other, and particularly in restricted areas such as passages, it is necessary to dispose them so that they take up the minimum of roan.

Where the application in a passage is also in a hazardous 11 environment, such as in a coal mine. where there is the danger of explosion fram incendive sparking, it is necessary to take steps to minimise this risk. One of the more common ways of doing this is by purging the system, as is shown for example in British Patent 5 Specification 2165509, where a special tank of purging gas is carried by a vehicle to supply gas under pressure at the pick-up point from a bus- bar. It is another object of the invention to ensure that the pick-up arrangement can be used in a hazardous environment with the minimum risk of explosion.

It is known that due to the irregularities of a path followed by an electric traction vehicle, there can be, as has been described above, a wandering of the pick-up or pantograph relative to the conductor. Generally, this would cause no problem, but clearly it is better if the pick-up runs centrally off the bus-bar and this ensures that a constant clean contact is maintained with the bus-bar. Furthermore in order to maintain a clean contact. it is necessary, as far as possible, to minimise the effect of dirt and moisture ingressed on to the bus-bar and the collector.

According to the present invention. an electrical current pick-up arrangement comprises a pair of longitudinally extending bus-bars and a respective co-operative moveable electrical pick-up member for each bus-bar in which each bus-bar is enclosed along its iength by an insulating housing having on one side a longitudinally extending slot and arranged in back to back relationship with the other bus-bar with the slots being disposed in opposite directions, and in which each pick-up member comprises an electrically insulating housing adapted to fit around part of the bus-bar housing and to be moveable along it,, each pick-up housing having an electrically conductive element arranged to extend through the slot in the respective bus-bar housing to contact the bus-bar.

In order to ensure safety from contactr the bus-bar is preferably of a general W configuration, having its outer-legs disposed against the inner walls of the housing and the recess of the W configuration opposite the longitudinal slot. A preferred cross section for the bus-bar housing is rectangular with the slot disposed centrally in one of the shorter sides of the housing walls.

Support means may be provided on the housing in such a manner as not to interfere with the passage of the pick-up means, and the support means may,, in a preferred embodiment,, be connected to the side of the housing opposite the longitudinal slot.

The electrical conductive element of the pick-up member may conveniently be a carbon brush, but may also be any suitable soft conductive material, such as copper or copper compound, which will make a good contact with the conductors of the bus-bar without causing undue wear and sparking.

The pick-up member is preferably spring-loaded and may conveniently be mounted on a support such as a bell crank lever which is mounted on a support ball arrangement to allow movement of the member in any direction. Preferabl yi springs control the movement of the bell crank lever to enable it to position the pick-up element centrally of the bus-bar. There may conveniently be four springs for each lever, arranged in pairs and connected between the housing and the lever at an angle. The loading of the springs may be different.

1 In order that the invention may be readily understood, one example of an electrical current pick-up arrangement in accordance therewith, will now be described by way of example only with reference to the two figures of the accompanying drawing. These figures show in detail the bus-bar and pick-up arrangement of a collector arrangement which is more fully described in our co-pending application (reference 4935). Figure 1 is a cross sectional view through a collector arrangement and through the busbar system and figure 2 is a part sectional view of the pick-up arrangement showing the spring loading of the pick-up element.

Referring now to the drawings, these show a collector arrangement which is encased in a general housing (1) which travels along a path defined by a guide rail (2). The general housing (1) includes a pair of bus-bars of which only one (3) is shown. the other is disposed within the housing (1) on the opposite side of a bracket (4) supporting a housing (5) of the busbar. The housing (5) is of an electrically insulating material and as can be seeny it is of a general rectangular configuration. One of the shorter sides of the housing (5) is connected to the support bracket (4), which in turn is secured to the guide rail (2). The opposite side of the housing (5) has a longitudinal slot (6). Within the housing, the bus-bar (3) is disposed as shown. The bus-bar is of a general W configuration, and as can be seen, the two outer limbs of the bus-barlie against the longer walls of the housing (5). The central portion of the bus-bar (3) is situated centrally within the centre of the housing (5) and is disposed at a distance such that it is not easy for anybody to put a finger through the slot (6) to make contact with the bus-bar (3). The slot (6) is, in fact, proportioned so that it can only take conveniently a pick-up element (7) of a pick-up member shown generally at (8). The element (7) is, in this example, a carbon brush and it is in the form of a longitudinally extending fin as shown. The element (7) is secured to an electrically insulating housing (9) of the pick-up member (8). This housing (9) is of a general open channel form having two upstanding walls which fit around part of the housing (5) of the bus-bar and which has its other wall supporting the pick-up element (7). The pick-up element (7) is connected to an electrical connector which extends through a terminal arrangement (10)t and this arrangement is connected to the vehicle (not shown) which is powered by electricity from the bus-bar.

Referring now also to figure 2, this shows how the pick-up element (7) is centralised and biased towards the bus-bar (3). A bell crank lever (11) is pivotally mounted on a post (12) in the general housing (1) on a bearing (13) which allows rotational movement of the lever (11) relative to the post (12). The bell cranklever (11) has two arms (14), (15) which have two pairs of springs (16), (17) respectively connected between their ends and the general housing (1). Since each of the springs (16), (17) is at an angle to the plane of the bell crank lever (11), each spring exerts a force on the lever which has both a horizontal and a vertical Ccmponent. The horizontal canponent which is in the plane of the bell crank lever is such as to urge the pick-up element (7) into the slot (6) and to enter good electrical engagement with the bus-bar (3). The vertical component of direction of the springs (16) and (17) are such as always to centralise the element (7) within the slot (6) and to account for irregularities of travel of the general housing (1) along the guide rail (2). The springs do not each have the same loading in order to offset the weight of the lever. The bearing (13) accommodates movement of the bell crank lever. This ensures that there is always a good and sufficient contact between the element (7) and the bus-bar (3).

In operation, as the housing (1) is moved along the guide rail (2), electric current is picked up from the bus-bar (3) by the pick-up element (7). Even at high speed as the element (7) moves along the bus-bar, the effect of the springs (16) and (17) on the bell crank lever (11) are around the bearing (13) that positioned within the slot contact with the bus-bar (3).

separate inlet to the general such as to ensure through the movement the element (7) is always correctly (6) and maintains a good electrical Purging air can be supplied through a housing (1) to ensure that if any sparking does take place between element (7) and bus-bar (3), then there is not an incendive atmosphere in the location of the sparking which could cause an explosion.

Due to the W formation of the bus-bar and its recessing within its awn housing (5) and the limited aperture of the slot (6), the bus-bar is finger safe and it is not possible for an operative accidentally to touch the bus-bar (3) if he grabs hold of the bus-bar at any point along its length. To add to the safety a flexible sealing lip could be included over the entry to the slot (6). This would be particularly useful in areas where the environment of the conductor is extremely dirty or moist.

It

Claims

CLAIMS: CASE 4933

1. An electrical current pick-up arrangement comprising a pair of longitudinally extending bus-bars and a respective co-operative moveable electrical pick-up member for each bus-bart in which each bus-bar is enclosed along its length by an insulating housing having on one side a longitudinally extending slot and arranged in a backto-back relationship with the other bus-bar with the slots being disposed in opposite directions, and in which each pick-up member ccmprises an electrically insulating housing adapted to fit around part of the bus-bar housing and to be moveable along it. each pick-up housing having an electrically conductive element arranged to extend through the slot in the respective bus-bar housing to contact the bus-bar.

2. An arrangement as claimed in claim 1, wherein each bus-bar is of a generally W configuration having the outer legs of the configuration disposed against the internal walls of its housing and the recess of the W opposite the longitudinally slot.

3. An arrangement as claimed in claim 1 or claim 2, wherein the bus-bar housing is in a general rectangular cross section with the slot centrally positioned along one of the shorter sides of the housing.

4. An arrangement as claimed in claim 3 and including support means for the bus-bar housing, the support means being connected to the housing on the side opposite the slot.

5. An arrangement as claimed in any preceding claim, wherein the pick-up element is a carbon brush.

6. An arrangement as claimed in any preceding claim, wherein the pick-up member is spring-loaded.

7

7. An arrangement as claimed in claim 6, wherein the pick-up member is spring-loaded in two directions to centralise the element within the busbar housing.

8. An arrangement as claimed in claim 6 or claim 7, and including a bell crank lever carrying the pick-up element and having springs attached to the lever for exerting forces in both their horizontal and vertical direction.

9. An arrangement as claimed in Claim 8 in which the springs ccmprise twn spring pairs, each pair being disposed on opposite sides of the lever and connected to the housing.

10. An arrangement as claimed in claim 9 in which the springs have different loadings.

11. An arrangement as claimed in claim 8 or 9 and including a ball mounting bearing for the bell crank lever.

12. An electrical current pick-up arrangement substantially as herein/before described and with reference to figures 1 and 2 of the accompanying drawings.

Published 1990 atThePatentOfflee. State House, 66171 High Holborn. London WClR4TP. Further copies maybe obtatnedfrom The Patent Office. Sales Branch, St Mary Cray. Orpington, Kent BRB 3RD. Printed by Multiplex techniques ltd, St MarY CrAY, Kent, Con. 1/87