Current collector for a non-rail-bound, electric traction vehicle, traction vehicle having a current collector of this type and method for operating a current collector of this type

Abstract

A current collector for a non-rail-bound, electric traction vehicle has an articulated support linkage, which, on the contact wire side, supports rocker assemblies with contact strips and, on the vehicle side, has a base joint for articulation to the traction vehicle. A pneumatic reciprocating drive is coupled to the support linkage for raising the rocker assemblies from a lower parking position into an upper contact position when the reciprocating drive is pressurized and for lowering into the parking position under its own weight when depressurization occurs. An exhaust air line connects the reciprocating drive to the environment to lower the rocker assemblies. An air accumulator and a downstream throttle valve are connected between the reciprocating drive and an environment opening of the exhaust air line. The rocker assemblies can be quickly lowered and nevertheless brought into the parking position without damage in order to disengage the current collector.

Claims

1. A current collector for a non-rail-bound, electric traction vehicle for feeding electrical energy from a two-pole overhead line system with contact wires forming forward and return conductors, the current collector comprising: an articulated support linkage, rocker assemblies with contact strips supported on a contact wire side of said support linkage, and a base joint for articulation of said support linkage to the traction vehicle; a pneumatic reciprocating drive coupled to said support linkage for selectively raising said rocker assemblies from a lower parking position into an upper contact position when said reciprocating drive is pressurized and lowering said rocker assemblies into the parking position under their own weight upon depressurization of said reciprocating drive; an exhaust air line for connecting said reciprocating drive to the environment in order to lower said rocker assemblies; an air accumulator and a throttle valve arranged downstream of said air accumulator connected between said reciprocating drive and an environment opening of said exhaust air line; and a storage capacity of said air accumulator being dimensioned to be less than an operating volume of said reciprocating drive.

2. A non-rail-bound, electric traction vehicle, comprising a current collector according to claim 1.

3. A method of operating a current collector of a non-rail-bound, electric traction vehicle for feeding electrical energy from a two-pole overhead line system with contact wires forming forward and return conductors, the method comprising: providing a current collector for a non-rail-bound, electric traction vehicle for feeding electrical energy from a two-pole overhead line system with contact wires forming forward and return conductors, the current collector having: an articulated support linkage, rocker assemblies with contact strips supported on a contact wire side of said support linkage, and a base joint for articulation of said support linkage to the traction vehicle; a pneumatic reciprocating drive coupled to said support linkage for selectively raising said rocker assemblies from a lower parking position into an upper contact position when said reciprocating drive is pressurized and lowering said rocker assemblies into the parking position under their own weight upon depressurization of said reciprocating drive; an exhaust air line for connecting said reciprocating drive to the environment in order to lower said rocker assemblies; and an air accumulator and a throttle valve arranged downstream of said air accumulator connected between said reciprocating drive and an environment opening of said exhaust air line; lowering the rocker assemblies in two stages, including a fast lowering phase from the contact position into an intermediate position and a parking lowering phase from the intermediate position into the parking position; during the fast lowering phase, enabling exhaust air to flow out of the reciprocating drive under the own weight of the rocker assemblies into the air accumulator with a first volume flow and, during the parking lowering phase, to flow out of the filled air accumulator through the throttle valve with a second volume flow that is restricted compared to the first volume flow.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a known current collector in a perspective view,

(2) FIG. 2 shows a circuit diagram of a pneumatic circuit for the operation of the current collector and

(3) FIG. 3 shows a time-distance diagram of the rocker assembly when it is lowered.

DETAILED DESCRIPTION OF THE INVENTION

(4) According to FIG. 1 a non-rail-bound, electric traction vehicle 1, in particular a road vehicle with a diesel electric drive, for instance a truck or bus, comprises a current collector 2, via which electrical energy can be fed from an overhead line system, including during the journey. The overhead line system is embodied as two-pole and comprises contact wires 3, 4 embodied as forward and return conductors running over a roadway, for the provision of electrical energy. The current collector 2 is embodied as a half-scissor pantograph and comprises an articulated support linkage 5 with a lower arm 6 and two upper arms 7, each of which is pivotably connected thereto by means of a shaft 8 arranged on the lower arm 6. Each of the two upper arms 7 supports a rocker assembly 9 on the contact wire side with two parallel contact strips 10 which are arranged one behind the other transversely to a vehicle longitudinal axis. To articulate the current collector 2 to the traction vehicle 1, the lower arm 6 is pivotably connected on the vehicle side to a base plate 12 via a base joint 11. The base plate 12 can for example be mounted on the roof of the traction vehicle 1, said roof being partially depicted in FIG. 1. The two upper arms 7 each have an end piece 13 projecting out over the shaft 8, through which a common shaft 14 extends. A connecting rod 15 is connected via the shaft 14 in an articulated manner to one of the end pieces 13 of the upper arms 7 in each case. Furthermore, the two connecting rods 15 are connected in an articulated manner to the base plate 12 via a cross-piece support 16.

(5) According to FIG. 2 a pneumatic reciprocating drive 17 in the form of an air-suspension bellows is coupled to the support linkage 5 such that the rocker assembly 9 can be raised from a lower parking position h.sub.P into an upper contact position h.sub.K when the reciprocating drive 17 is pressurized. The pressurization is effected by a pressurized air supply 18, which may include—not depicted in greater detail—a compressor, a pressurized air container, an oil/water separator and a pressure control device. Suitable mechanical coupling means 19 convert a linear positioning force of the reciprocating drive 17 into a torque of the lower arm 6 in the base joint 11. In the parking position h.sub.P the support linkage 5 of the disengaged current collector 2 is folded up, such that the traction vehicle 1 does not exceed the permissible overall vehicle height to be adhered to when operating outside electrified routes and the current collector 2 is positioned in an electrically safe state. The current collector 2 must also be disengaged before the traction vehicle 1 switches safely to a non-electrified traffic lane, for instance during overtaking maneuvers. When the current collector 2 is engaged, the connecting rods 15 force the upper arms 7 to be raised if the lower arm 6 is raised. In the contact position h.sub.K the contact strips 10 of the rocker assemblies 9 are each pressed onto one of the contact wires 3, 4 of the overhead line system, such that both when stationary and during the journey energy can be transmitted from the overhead line system to the traction vehicle 1. In order to transfer the rocker assemblies 9 from the contact position h.sub.K into the parking position h.sub.P a depressurization of the reciprocating drive 17 takes place, such that under their own weight the rocker assemblies 9 are lowered and the support linkage 5 folds up. Pressurized air then escapes from the reciprocating drive 17 into the environment via an exhaust air line 20.

(6) According to the invention an air accumulator 22 and a throttle valve 23 arranged downstream thereof are connected between the reciprocating drive 17 and an environment opening 21 of the exhaust air line 20. A storage capacity of the air accumulator 22 is preferably in this case dimensioned to be less than an operating volume of the reciprocating drive 17. An electrically actuatable two-way valve 24, to which an intake air line 25 coming from the pressurized air supply 18 is also connected, is arranged in the exhaust air line 20 between the reciprocating drive 17 and the air accumulator 22. In the actuated state of the two-way valve 24 a pneumatic connection exists between the pressurized air supply 18 and the reciprocating drive 17, such that the current collector 2 can be engaged or in the engaged state a downforce of the contact strips 10 onto the contact wires 3, 4 can be controlled. In this state the section of the exhaust air line 20 running between the two-way valve 24 and the reciprocating drive 17 is used as an intake air line. In the electrically non-actuated state the two-way valve 24 releases a pneumatic connection between the reciprocating drive 17 and the air accumulator 22, while the connection of the intake air line 25 is blocked. This state is also adopted if the two-way valve 24 is without current as a result of a fault, so that in the event of a fault an automatic lowering of the current collector 2 is initiated.

(7) On termination of the actuation of the two-way valve 24 at a time t.sub.K at which the rocker assemblies 9 according to FIG. 3 are in their upper contact position h.sub.K, the reciprocating drive 17 is depressurized and the pressurized air located in its operating volume escapes into the air accumulator 22, under the own weight of the rocker assemblies 9, until the air accumulator 22 is full. If the storage capacity of the air accumulator 22 is dimensioned to be less than the operating volume of the reciprocating drive 17, the lowered rocker assemblies 9 adopt an intermediate position h.sub.Z at this time t.sub.Z which lies only slightly above the parking position h.sub.P. As from the time t.sub.Z the exhaust air flow—still driven by its own weight—out of the air accumulator 22 into the environment is reduced by the cross-section of the downstream throttle valve 23, until the rocker assemblies 9 have reached their lower parking position h.sub.P at time t.sub.P.

(8) According to the invention, the lowering of the rocker assemblies 9 takes place in two stages in a first fast lowering phase of the period t.sub.K-t.sub.Z and in a second parking lowering phase of the period t.sub.P-t.sub.Z. During the fast lowering phase the air flows out of the reciprocating drive 17 into the air accumulator 22 with a first volume flow which is mainly determined by the line cross-section of the exhaust air line 20, whereas during the parking lowering phase air flows out of the air accumulator 22 into the environment with a second volume flow. The second volume flow is restricted by the small, adjustable cross-section of the throttle valve 23 compared to the first volume flow, such that the lowering speed of the rocker arrangements 9 in the parking lowering phase is less than during the fast lowering phase. This means that on termination of the actuation of the two-way valve 24 the rocker assemblies 9 travel a comparatively long lowering path h.sub.K-h.sub.Z into the intermediate position h.sub.Z in a comparatively short period t.sub.Z-t.sub.K, in order quickly to put a distance between themselves and the contact wires 3, 4 of the overhead line system. Furthermore, the rocker assemblies 9 traverse the remaining lowering path h.sub.Z-h.sub.P slowly, so that the current collector 2 moves gently into its parking position h.sub.P, without being exposed to high mechanical impact stresses. This is advantageously achieved according to the invention without the use of expensive controllable throttle valves.