DE19920384C1 - Earth contact for rail cars for transferring current between vehicle parts and rotating wheelset shaft has silver graphite abrasive strips and electrolytic copper abrasive body - Google Patents

Abstract

Earth contact (15) has abrasive strips (16) joined directly to an abrasive body (21) which is connected to a wheelset shaft (25). The abrasive strips are made of silver graphite and the abrasive body is made of electrolytic copper.

Description

The invention relates to a ground contact for elek trically operated rail vehicles.

For electrically powered locomotives, drive and travel the circuit is pulled by the return via Bogie, axle, wheel and rail closed. The kri The table position in the current flow is the roller bearing, at which even small electrical loads can damage it cause the surface and a bearing replacement make it necessary to face an impending total failure avoid. For this reason, for the current feedback Earthing contacts used. These current bridges len a low-resistance connection via a sliding contact dung z. B. between the standing axlebox and the rotating wheelset shaft. By a suitable one Isolation of the wheelset bearings will exclude electricity Lich through the earth contact directly into the wheelset shaft  initiated. A parallel current path is out of order Appropriate protective resistors are not permitted sig.

Conventional ground contacts where the grinding piece made of metal graphite and the grinding wheel made of bronze exist, are very suitable for operating current return leadership on rail vehicles.

For low-floor vehicles with non-electrically connected The earth contact is also used for the pairs of wheels called axis short circuit needed to an electrical Connection of the wheel pairs for signal control put. The signal currents are very low. Conventio nell earthing contacts are therefore for this application case unsuitable because of the contact surface of Grinding piece and grinding body an insulating pati forms a layer that prevents the flow of signal currents changed or at least adversely affected.

A ground contact is known from EP 0 582 888 B1, where the contact surface of the contact strip and grinding consists of carbon material or ent holds. This pairing of materials is intended to reduce wear and thus increase the maintenance intervals.

The invention is based on the prior art Task based, one for operational use to create improved ground contact with a low against transmission resistance that is not susceptible to ver dirt and mechanical loads.

Two independent solutions to the problem according to the invention form the subject of claims 1 and 2, their technolo gical connection in the use of the material pair  Silver graphite and electrolytic copper for contact strip or grinding wheel of an earth contact can be seen.

According to claim 1, the contact strip consist of Silbergra phit and the grinding tool made of electrolytic copper gene claim 2 provides that the contact strip made of Elek trolyt copper and the grinding tool made of silver graphite are.

The electrical material pairing used according to the invention Lyt copper / silver graphite creates an earth contact a constant low transmission resistance at the Contact surface between the grinding piece and grinding wheel. Accordingly, signal currents can be transmitted correctly the. Compared to the use of pure carbon material has positive effects that electrolytic copper and silver graphite are less brittle and prone to breakage.

Ground contacts of common design can be replaced the grinding pieces and the grinding body in the simplest Way to be retrofitted. Special adapters there is no need to hold the components Lich.

The materials are electrolytic copper and silver graphite insensitive to impurities such as fat, oil and the like. This contributes to the high functional reliability of the Grounding contact and wear reduction.

Furthermore, a high current density is realized. In order to the components can be made smaller, so that The volume of the earth contact is compact overall fails.

According to the features of claim 3 comes a silver gra phit, whose silver content is greater than 85%  is. In practical tests, very good results have been obtained achieved with a silver content of 90% or above. There with a constant low transmission wi the level of ≦ 20 mOhm can be reached.

The invention is below with reference to the drawing gene described. Show it:

Fig. 1 shows the functional diagram of an electrical connection Ver via two ground contacts in a low-floor vehicle and

Fig. 2 shows an embodiment of a grounding contact according to the invention.

Fig. 1 shows a wheel set 1 of a rail-bound which is electrically operated low-floor vehicle, of which otherwise only the car body bogie 2 is shown in a technically simplified manner.

The wheel set 1 essentially comprises two running wheels 4 on rails 3 , which are supported with their wheel set shafts 5 in wheel set roller bearings 6 . The Radsatz-Rol lenlager 6 are arranged in axlebox housings 7 , on which the car body bogie 2 rests with the inclusion of insulation 8 .

The overhead line from a catenary or a third rail is carried out via the wheelset shafts 5 and the wheels 4 to the running rail 3 and thus to the energy source. The transmission of the fixed driving parts on the rotating wheelset 5 takes place via ground contacts 9 to bridge the wheelset roller bearings 6 with low resistance.

A grounding contact 9 produces an electrically good conductive connection via a contact piece 10 and a grinding element 11 , which is connected to the wheel set shaft 5 . In the basic exemplary embodiment shown here, the contact strip 10 is not rotatably mounted in a housing 12 and is loaded by a spring 13 against the rotating grinding member 11 . By means of suitable insulation of the wheel set roller bearings 6 , the current is introduced directly into the wheel set shafts 5 exclusively through the grounding contacts 9 . The housing 12 is coupled to the wheel set bearing housing 7 and forms its outer cover-like closure.

An axis short circuit, that is to say an electrical connection of the wheels 4 for signal control, is established via an earth line 14 . This makes contact between the contact strips 10 . The axis short circuit is illustrated by the arrow P.

The contact strip 10 consists of silver graphite (SG). The grinding wheel 1 is made of electrolytic copper (E-Cu). This pairing of materials ensures a constantly low transmission resistance at the contact surface between the grinding piece 10 and the grinding body 11 .

The grounding contact 15 of a wheel set internally mounted Fig. 2 shows.

A contact strip 16 made of silver graphite (SG) is zen on a pin 17 in the cover 18 of the ground contact housing 19 and is fastened with the aid of a clamping ring 20 .

The grinding piece 16 contacts a grinding body 21 made of electrolytic copper (E-Cu). The pressure between the grinding piece 16 and grinding body 21 is brought about by a spring, not shown here. The grinding wheel 21 is formed by a contact disk 22 which is received with its socket-shaped shoulder 23 in a sleeve 24 of the wheel set shaft 25 in a positive and frictional manner.

The seal between the grounding contact housing 19 and the wheel set shaft 25 is ensured by a seal 26 which is held in the cover 27 made of an electrically insulating, preferably plastic.

From the grinding wheel 21 there is at least the contact disk 22 made of electrolytic copper (E-Cu). The contact strip 16 is a silver graphite (SG), the silver content of which is greater than 85%. The silver content is preferably about 90% or above. It is possible within the scope of the invention to form the grinding piece 16 and grinding body 21 by composite materials, but the pairing of silver graphite and electrolytic copper is present at least in the area of the contact area.

List of reference symbols

1

Wheelset

2nd

Car body bogie

3rd

Track

4th

wheel

5

Wheelset shaft

6

Wheelset roller bearings

7

Wheelset bearing housing

8th

isolation

9

Earth contact

10th

Contact strip

11

Grinding wheel

12th

casing

13

feather

14

Ground wire

15

Earth contact

16

Contact strip

17th

Cones

18th

cover

19th

Earth contact housing

20th

Clamping ring

21

Grinding wheel

22

Contact washer

23

approach

24th

Sleeve

25th

Wheelset shaft

26

poetry

27

cover
P axis short circuit

Claims (3)

1. Grounding contact for electrically operated rail vehicles for the transmission of currents between stationary vehicle parts and rotating wheelset shaft ( 5 , 25 ), which has at least one contact piece ( 10 , 16 ), which is connected at least indirectly with the wheelset shaft ( 5 , 25 ) Contacted grinding wheel ( 11 , 21 ), characterized in that the grinding wheel ( 10 , 16 ) consists of silver graphite (SG) and the grinding wheel ( 11 , 21 ) consists of electrolytic copper (E-Cu). 2. Earth contact for electrically operated rails vehicles for transferring currents between fixed stationary vehicle parts and rotating wheelset shaft, which has at least one contact piece which ver at least indirectly with the wheelset shaft bonded grinding wheel contacted, thereby characterized that the contact strip made of electrolytic copper (E-Cu) and the grinding wheel Silver graphite (SG) exist. 3. Earth contact according to claim 1 or 2, characterized characterized that the silver content in Silver graphite (SG) greater than 85%, preferably is greater than 90%.