Abstract
A sand spreading system for a rail vehicle with driveable and/or brakeable rail wheels. The sand spreading system includes a sand box for storing spreading sand, a sand staircase which is fastened to the sand box for the compressed-air-controlled metering of the output of spreading sand, and a sand outlet tube which is connected to the sand staircase via a sand hose and opens in front of a rail wheel. By a heating device for generating a hot air flow passing through the spreading sand being integrated in the sand staircase, the spreading sand can be kept dry and pourable even in the wet and frost, and therefore the function of the sand staircase and hence the effective operation of the rail vehicle are assured.
Claims
1. A sand spreading system for a rail vehicle with rail wheels, the sand spreading system comprising: a sandbox for storing spreading sand, a sand stairway fastened to said sandbox and configured for compressed-air-controlled metering of a spreading sand output; a sand outlet tube opening out in front of a rail wheel, and a sand hose connecting said sand outlet tube to said sand stairway; a heating device integrated into said sand stairway for generating a hot air stream to flow through the spreading sand; said sand stairway having a stairway housing with an integrally formed fastening flange for fastening to said sandbox; said fastening flange being formed with a sand inlet opening and a channel system for accommodating said heating device and for conducting an air stream that passes through said heating device, said channel system having at least two parallel channels on opposite sides of said inlet opening and at least one outlet for the air stream; said sand outlet tube being below and laterally offset from said sand inlet opening, and said sand stairway having an angled surface configured to receive sand from said sand box through said sand inlet opening and direct sand laterally to said sand hose and said sand outlet tube; and a sintered filter disposed at said at least one outlet of said channel system, wherein the air stream heated by said heating device flows through said sinter filter and into the sandbox.
2. The sand spreading system according to claim 1, wherein said channel system includes one or more port openings each configured to receive a rod-shaped heating element of said heating device to be inserted from outside.
3. The sand spreading system according to claim 2, wherein said stairway housing is formed as a single piece.
4. The sand spreading system according to claim 1, wherein said channel system is formed with one or more inlets for a supply air stream.
5. The sand spreading system according to claim 4, wherein the supply air stream is controllable independently of a compressed air stream to be fed to said sand stairway for metering the output of spreading sand.
6. The sand spreading system according to claim 5, wherein said sintered filter has a frustoconical shape and projects from said fastening flange into said sandbox.
7. A rail vehicle, comprising at least one rail wheel to be driven and/or braked, and a sand spreading system according to claim 1.
8. The rail vehicle according to claim 7 being a locomotive.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) Further characteristics and advantages of the invention will emerge from the following description of the drawings, in which, in each case schematically,
(2) FIG. 1 shows a sanding system according to the invention with sand stairway in a partially sectional side view,
(3) FIG. 2 shows a section through the fastening flange of the sand stairway along the section line II-II indicated in FIG. 1,
(4) FIG. 3 shows the sanding system as per FIG. 1 in a plan view, and
(5) FIG. 4 shows a longitudinal section through the fastening flange of the sand stairway along the section line IV-IV indicated in FIG. 3.
DESCRIPTION OF THE INVENTION
(6) As per FIG. 1, a sand spreading system 1 for a rail vehicle (not illustrated), for example a locomotive, with rail wheels which can be driven and/or braked comprises a sandbox 36 for storing spreading sand. Below the sandbox 36, there is fastened a sand stairway 2 for the compressed-air-controlled metering of the output of spreading sand. The sand stairway 2 is connected via a sand hose 38 to a sand outlet tube 40 which opens out in front of the rail wheel in a direction of travel. The parts which are not illustrated are known per se. The sand stairway 2 has a stairway housing 3 formed as a single-piece cast part, through which a siphon-like, substantially S-shaped sand path extends. The stairway housing 3 has a fastening flange 4 for the fastening thereof to the sandbox 36. Spreading sand emerges from the sandbox 36 through a sand inlet opening 5 provided in the fastening flange 4, and slides into a funnel-shaped depression 6, adjoining said sand inlet opening, of the stairway housing 3. The base wall 7 of the depression 6 expediently has an angle of inclination which, in relation to the angle of repose of the spreading sand used, promotes a sliding-down movement. The depression 6 is adjoined by a horizontal, relatively narrow channel piece 8 which acts as a throttling point for the spreading sand that slides down. In this way, a situation is prevented in which an excessive amount of spreading sand slides down out of the sandbox 36 in the event of vibrations of the rail vehicle. The channel piece opens into a sand chamber 9 which is separated by a vertical partition 10 from a blow-out channel 11 of the stairway housing 3. Here, an apex 12 of the channel piece 8 is situated below an upper edge 13 of the partition 10 and thus below an inlet opening of the blow-out channel 11 extending vertically downward from said upper edge. Above the blow-out channel 11 and the sand chamber 9, compressed air is fed from above via a nozzle block 14, which has two nozzles 30, 31, of the stairway housing 3. From a first nozzle 30, an air jet flows into the sand chamber 9, such that spreading sand is swirled up therein. The swirled-up spreading sand is entrained by the air jet flowing out of the second nozzle 31, and is conveyed through the blow-out channel 11, which it exits through a sand outlet opening 15 of the stairway housing 3. Connected to the sand outlet opening 15 is the sand hose 38 which ends with the sand outlet tube 40 and from which the gap between rail wheel and rail is impinged on with spreading sand for the purposes of increasing the friction coefficient.
(7) As per FIG. 1 to FIG. 4, a heating device 16 for generating a hot air stream which flows through spreading sand is integrated into the sand stairway 2 according to the present invention. In this way, the spreading sand is dried and kept in a pourable state. By integrating the heating device 16 into the sand stairway 2, additional components and associated production and assembly costs are saved. For the integration of the heating device 16, a channel system for accommodating the heating device 16 and for conducting an air stream which passes through the heating device 16 extends in the fastening flange 4 of the stairway housing 3.
(8) As per FIG. 2, the channel system runs parallel to an approximately square flange surface 17 of the fastening flange 4, and has two parallel longitudinal channels 18 and, perpendicular to these, a transverse channel 19 which intersects the longitudinal channels 18, whereby a communicating channel system is formed. Each of the longitudinal channels 18 runs from a lateral port opening 20 into the fastening flange 4 and opens into in each case one blind bore situated to both sides of the rectangular sand inlet opening 5, which blind bore is open to the flange surface 7 and forms an outlet 21. Through a port opening 19, a rod-shaped heating element 22 of the heating device 16 is inserted from the outside into the longitudinal channel 18 and is fastened by means of a screw connection. Depending on the heat quantity required for the drying of the spreading sand, the port opening 20 of the other longitudinal channel 18 can either be closed off by means of a closure piece (not illustrated) or equipped with a second rod-shaped heating element 22 (likewise not illustrated). For the compressed-air-tight closure of the port openings 20, the longitudinal channels 18 have internal attachment threads for the screw connections. The transverse channel 19 is formed as a passage bore and, at opposite face surfaces of the fastening flange 4, has in each case one inlet 23 to which a compressed air line (not illustrated) for the feed of a supply air stream can be connected. If a greater supply air stream is required for the drying of the spreading sand, for example if both longitudinal channels 18 are equipped with heating elements 22, compressed air lines may be connected to both inlets 23. Otherwise, the inlet 23 that is not required for a compressed air line is closed in compressed-air-tight fashion by means of a closure piece. A particular advantage lies in the separation of the supply air stream provided via the compressed air lines from the compressed air stream fed for the metering of the output of spreading sand, such that the former is controllable independently of the spreading sand requirement, only in accordance with the present heat requirement.
(9) As per FIG. 4, a heating element 22 comprises an external hexagonal portion 24 for the engagement of a fastening tool, an adjoining external thread portion 25 for the screw connection to the internal attachment thread of the longitudinal channel 18, and a heating rod 26 adjoining said external thread portion, which heating rod extends through the longitudinal channel 18 almost as far as the outlet 21. The heating rod 26 converts electrical energy, which is fed by means of supply lines 27 connected externally at the end side, into heat energy. From the one or more lateral inlets 23, a supply air stream flows through the transverse channel 19 onward into the longitudinal channels 18 through a ring-shaped gap 28 surrounding the heating rod 26. Here, the air flowing past the heating rod 26 heats up and forms a hot air stream, which flows through the outlet 21 into the spreading sand to be dried. At the outlet 21, there is arranged a sintered filter 29 which is permeable to the hot air stream but not to spreading sand, in order to prevent blockage of the outlet 21. The sintered filter 29 screwed into the outlet 21 is of frustoconical form and projects upward from the flange surface 17 of the fastening flange 4 into the sandbox. The hot air stream exiting the one or more sintered filters 29 flows upward through the downwardly sliding spreading sand in the sandbox. By means of this opposing flow principle, particularly effective drying of the spreading sand is achieved. Additionally, by means of the elongate heating rods 26, the fastening flange 4 is heated up, which additionally releases heat to the downwardly sliding spreading sand. Owing to the single-piece form of the stairway housing 3 formed as a cast part or 3D printed part, said stairway housing is also heated, by heat conduction, in the region of the depression 6, such that the spreading sand situated therein is also dried.
