Abstract
A sand stairway for a sand-spreading system of a rail vehicle has a stairway housing with a sand compartment for providing sliding spreading sand. A blow-out duct discharges spreading sand from the stairway housing. First and second nozzle inserts are releasably inserted into first and second receiving holes of a nozzle flange of the stairway housing above the sand compartment. The nozzle inserts are produced separately from the stairway housing. The first nozzle insert produces an air jet directed into the sand compartment and swirls up spreading sand. The second nozzle insert produces an air jet directed into the blow-out duct and swirls up spreading sand. A sand-spreading system for a rail vehicle has a sand stairway for the compressed-air-controlled metering of the discharged spreading sand. The novel sand stairway has increased flexibility and can be set up without great effort for using different types of spreading sand.
Claims
1. A sand stairway for a sand-spreading system of a rail vehicle, the sand stairway comprising: a stairway housing with a sand compartment for providing progressively sliding spreading sand and with a blow-out duct for discharging spreading sand from the stairway housing; a nozzle flange disposed above said sand compartment and said blow-out duct, said nozzle flange being formed with a first receiving bore and a second receiving bore; a first nozzle for producing an air jet that is directed into said sand compartment for swirling up spreading sand, said first nozzle having a first nozzle insert produced separately from said stairway housing and releasably inserted into said first receiving bore; a second nozzle for producing an air jet that is directed into said blow-out duct for discharging swirled-up spreading sand, said second nozzle having a second nozzle insert produced separately from said stairway housing and releasably inserted into said second receiving bore; said nozzle inserts having nozzle diameters tailored to a type of spreading sand used in the sand-spreading system; said nozzle inserts being replaceable upon contamination; and said nozzle inserts selectively having mutually different nozzle diameters or identical nozzle diameters, in dependence on operating requirements.
2. The sand stairway according to claim 1, comprising a compressed-air flange releasably fastened to said nozzle flange in a compressed-air-tight manner and, extending therein, a compressed-air duct which leads from a connection opening for a compressed-air line to a first outlet, which opens into said first nozzle insert, and to a second outlet, which opens into said second nozzle insert.
3. The sand stairway according to claim 1, wherein a nozzle diameter of said first nozzle insert is smaller than a nozzle diameter of said second nozzle insert.
4. The sand stairway according to claim 1, wherein each said first and second nozzle inserts are selected from a set of nozzle inserts having differently dimensioned nozzle diameters corresponding to a particle size of the spreading sand used.
5. The sand stairway according to claim 1, wherein said stairway housing is a one-piece fine casting or a 3D-printed part.
6. The sand stairway according to claim 5, wherein said stairway housing consists of stainless steel.
7. The sand stairway according to claim 1, wherein said nozzle inserts are turned brass parts.
8. A sand-spreading system for a rail vehicle having rail wheels to be driven and/or braked, the sand-spreading system comprising: a sand box for storing spreading sand; a sand stairway according to claim 1 fastened to said sand box and configured for compressed-air-controlled metering of a spreading-sand output; and a sand outlet pipe connected via a sand hose to said sand stairway and opening ahead of a rail wheel in a travel direction.
9. A rail vehicle, comprising: at least one rail wheel to be driven and/or braked; and a sand-spreading system having: a sand box for storing spreading sand; a sand stairway according to claim 1 fastened to said sand box and configured for compressed-air-controlled metering of a spreading-sand output; and a sand outlet pipe connected to said sand stairway and opening ahead of said at least one rail wheel in a travel direction of the rail vehicle.
10. The rail vehicle according to claim 9 being a locomotive.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) Further properties and advantages of the invention will become apparent from the following description of the drawings, in which
(2) FIG. 1 schematically illustrates a sand stairway according to the invention in plan view, and
(3) FIG. 2 schematically illustrates a longitudinal section through the sand stairway along the section line II-II indicated in FIG. 1.
DESCRIPTION OF THE INVENTION
(4) A sand stairway 1 shown in FIG. 1 and FIG. 2 serves for the compressed-air-controlled metering of the spreading-sand output of a sand-spreading system, which is known per se in its entirety and therefore not illustrated, for a rail vehicle, which is likewise not illustrated. The rail vehicle comprises rail wheels which can be driven and/or braked, and can be, for example, a locomotive or a multiple unit. The sand-spreading system further includes a sand box for storing spreading sand which progressively slides into the sand stairway 1. Spreading sand leaves the sand stairway 1 through a sand hose (not shown), which in turn is connected to a sand outlet pipe which opens ahead of the rail wheel in the direction of travel. The stairway housing 2 is designed as a one-piece component, in particular as a fine casting or 3D-printed part, the high dimensional accuracy of which avoids associated finishing work. Here, it can be produced in particular from stainless steel, with the result that separate measures for corrosion protection can be dispensed with. A siphon-like, substantially S-shaped sand path extends through the stairway housing 2. The stairway housing 2 has a fastening flange 3 for fastening it to the sand box. Spreading sand exits the sand box through a sand inlet opening 4 provided in the fastening flange 3 and slides into an adjoining, funnel-shaped trough 5 of the stairway housing 2. The bottom wall 6 of the trough 5 expediently has an angle of inclination which is greater than the pouring angle of the spreading sand used. The trough 5 is adjoined by a horizontal, relatively narrow duct section 7 which acts as a throttle point for the progressively sliding spreading sand. This avoids a situation in which an excessive amount of spreading sand slides progressively out of the sand box when the rail vehicle is subject to vibrations. The duct section 7 opens into a sand compartment 8 which is separated by a vertical partition 9 from a blow-out duct 10 of the stairway housing 2. Here, an apex 11 of the duct section 7 is situated below an upper edge 12 of the partition 9 and thus below an inlet opening of the blow-out duct 10 which extends vertically downward therefrom. A nozzle flange 13 (not illustrated in FIG. 1), in which two vertical receiving bores 14 and 15 configured as through-holes are arranged, is formed above the blow-out duct 10 and the sand compartment 8 in a knee region of the stairway housing 2. A first nozzle insert 16 is releasably inserted into the first receiving bore 14, and a second nozzle insert 17 is releasably inserted into the second receiving bore 15. The nozzle inserts 15 and 16 are preferably configured as turned parts consisting of brass and can thereby be produced with a high degree of precision in terms of their nozzle diameters. A compressed-air flange 19 is placed on the nozzle flange 13 in a compressed-air-tight manner with the interposition of a seal 18 but releasably fastened by means of a screw connection. Within the compressed-air flange 13, a compressed-air duct 20 extends from a connection opening 21 for a compressed-air line (not illustrated) to a first outlet 22, which opens into the first nozzle insert 16, and leads to a second outlet 23, which opens into the second nozzle insert 17. Compressed air is fed in via the compressed-air flange 19 to the nozzle flange 13 of the stairway housing 2, flows through the first nozzle insert 16 into the sand compartment 8 and produces an air jet for swirling up spreading sand. The compressed air also flows through the second nozzle insert 17 and produces an air jet which discharges the swirled-up spreading sand through the blow-out duct 10. Since the nozzle inserts 16 and 17 are jointly supplied with compressed air, the nozzle diameter of the first nozzle insert 16 can be dimensioned to be smaller than the nozzle diameter of the second nozzle insert 17 if the conveying air jet may have a greater volumetric flow than the swirling-up air jet. The swirled-up spreading sand is entrained by the air jet and conveyed through the blow-out duct 10, which it leaves through a sand outlet opening 24 of the stairway housing 2. The sand hose terminating with a sand outlet pipe is connected to the sand outlet opening 24 and jets the gap between rail wheel and rail with spreading sand to increase the coefficient of friction.
(5) According to FIG. 2, the first and second nozzle insert 16 and 17 are turned from brass as cylindrical sleeves. They have an axial through-bore which defines the precise nozzle diameter. The through-bores have conical countersinks at the downstream end, whereas they are cylindrically drilled at the upstream end. At the latter end, the nozzle inserts 16 and 17 in each case have a flat, cylindrical extension which fits into a corresponding countersink of the receiving bores 14 and 15. The shape thereof allows a simple plugging of the nozzle inserts 16 and 17 into the receiving bores 14 and 15 and a likewise simple removal, with the result that, in the sand stairway 1 according to the invention, a change of nozzle inserts 16 and/or 17 can be carried out without great effort. As a result, clogged nozzle inserts 16 and 17 can be quickly replaced with clean ones, or the nozzle inserts 16 and 17 can be exchanged for others having smaller or larger nozzle diameters. For this purpose, a set of nozzle inserts 16 and 17 having different nozzle diameters is available according to the invention.
