Abstract
A chassis for a rail vehicle, in particular for a locomotive. A chassis frame is supported on first and second wheel sets and one triangular link per wheel set on both sides of the chassis for horizontally guiding the axle of the wheel set. An A-arm is hinged to one of two axle bearings by a wheel set-side bearing and by two frame-side bearings. The latter have elastomer bushings with a constant longitudinal and transverse rigidity. The former have hydraulic bushings with constant transverse rigidity and variable longitudinal rigidity. The bearings of each A-arm are arranged on the corners of a horizontal isosceles triangle. The tip of the triangle forms the wheel set-side bearing and the base forms the frame-side bearings. This resolves the conflicting objectives between dynamic running behaviors of the chassis when cornering and the driving stability when traveling straight ahead at a high speed.
Claims
1. A chassis for a rail vehicle having wheel sets with axles and axle bearings, the chassis comprising: a chassis frame supported at least on a first wheel set and a second wheel set of the rail vehicle; an A-arm disposed on each wheel set on both sides of the chassis for horizontally guiding the axle of the wheel set; a wheel-set-side bearing hinging a respective said A-arm to one of two axle bearings of a wheel set and two frame-side bearings hinging said A-arm to said chassis frame; said frame-side bearings having elastomer bushings with constant longitudinal and transverse rigidity and said wheel-set-side bearings having hydraulic bushings with constant transverse rigidity and variable longitudinal rigidity; said frame-side and wheel-set-side bearings of each said A-arm being arranged on corners of a horizontally aligned isosceles triangle, the triangle having a tip forming said wheel-set-side bearing and a base forming said frame-side bearings, each of said hydraulic bushings having an externally located fluid chamber in a longitudinal direction and an internally located fluid chamber in the longitudinal direction, which are arranged opposite one another in the longitudinal direction and are filled with a hydraulic fluid, each of said fluid chambers being connected to a fluid duct through which hydraulic fluid can flow into or out of the fluid chamber, wherein the longitudinal rigidity of said hydraulic bushing varies as a function of an excitation frequency of fluid flows forced into or out of a fluid chamber by wheel set guiding forces; said hydraulic bushings arranged on a same chassis side are connected via external fluid ducts such that said externally located fluid chamber of said first wheel set is hydraulically coupled to said internally located fluid chamber of said second wheel set and said internally located fluid chamber of said first wheel set is hydraulically coupled to said externally located fluid chamber of said second wheel set; a pressure sensor assigned to and coupled with each said fluid chamber via a fluid duct, said pressure sensor responding when a pressure prevailing in the hydraulic fluid falls below a pre-defined threshold value, said pressure sensors being connected individually and/or serially to a pressure monitoring device, and the pressure monitoring device is configured for transmitting a warning signal to a central control device of the rail vehicle when one or all of said pressure sensors respond.
2. The chassis according to claim 1, wherein a frame-side bearing includes a bearing bolt pushing vertically through said elastomer bushing, said bearing bolt having holes formed therein horizontally through said bearing bolt, for guiding there through fixing devices for connecting said bearing to said chassis frame above and below said elastomer bushing.
3. The chassis according to claim 1, wherein a wheel-set-side bearing includes a bearing bolt pushing vertically through said hydraulic bushing, said bearing bolt having a hole formed therein vertically through said bearing bolt, for guiding fixing devices coaxially through the hydraulic bushing for connecting said bearing to the axle bearing of the wheel set.
4. The chassis according to claim 1, wherein each of said hydraulic bushings has an internal fluid duct hydraulically coupling said externally located fluid chamber and said internally located fluid chamber to the same hydraulic bushing.
5. The chassis according to claim 1, wherein a third wheel set is arranged between the first wheel set and the second wheel set.
6. The chassis according to claim 1, configured for a locomotive.
7. A chassis for a rail vehicle having wheel sets with axles and axle bearings, the chassis comprising: a chassis frame supported at least on a first wheel set and a second wheel set of the rail vehicle; an A-arm disposed on each wheel set on both sides of the chassis for horizontally guiding the axle of the wheel set; a wheel-set-side bearing hinging a respective said A-arm to one of two axle bearings of a wheel set and two frame-side bearings hinging said A-arm to said chassis frame; said frame-side bearings having elastomer bushings with constant longitudinal and transverse rigidity and said wheel-set-side bearings having hydraulic bushings with constant transverse rigidity and variable longitudinal rigidity; said frame-side and wheel-set-side bearings of each said A-arm being arranged on corners of a horizontally aligned isosceles triangle, the triangle having a tip forming said wheel-set-side bearing and a base forming said frame-side bearings; each of said hydraulic bushings having an externally located fluid chamber in a longitudinal direction and an internally located fluid chamber in the longitudinal direction, which are arranged opposite one another in the longitudinal direction and are filled with a hydraulic fluid, each fluid chamber being connected to a fluid duct through which hydraulic fluid can flow into or out of the fluid chamber, wherein the longitudinal rigidity of said hydraulic bushing varies as a function of an excitation frequency of fluid flows forced into or out of a fluid chamber by wheel set guiding forces; each of said hydraulic bushings having an internal fluid duct hydraulically coupling said externally located fluid chamber and said internally located fluid chamber to the same hydraulic bushing; a pressure sensor assigned to and coupled with each said fluid chamber via a fluid duct, said pressure sensor responding when a pressure prevailing in the hydraulic fluid falls below a pre-defined threshold value, said pressure sensors being connected individually and/or serially to a pressure monitoring device, and the pressure monitoring device is configured for transmitting a warning signal to a central control device of the rail vehicle when one or all of said pressure sensors respond.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) Other features and advantages of the inventive chassis will emerge from the following description with the help of the drawings. These are schematic illustrations in which:
(2) FIG. 1 shows a two-axle exemplary embodiment of the inventive chassis viewed from above,
(3) FIG. 2 shows a three-axle exemplary embodiment of the inventive chassis viewed from above,
(4) FIG. 3 shows a partially cut away side view of an A-arm,
(5) FIG. 4 shows the A-arm according to FIG. 3, viewed from above,
(6) FIG. 5 graphically illustrates the frequency dependency of the longitudinal rigidity of a hydraulic bushing of the A-arm,
(7) FIG. 6 shows a further two-axle exemplary embodiment of the inventive chassis viewed from above,
(8) FIG. 7 shows a first circuit of pressure sensors for transmitting signals to a pressure monitoring device,
(9) FIG. 8 shows a second circuit of pressure sensors for transmitting signals to a pressure monitoring device.
DESCRIPTION OF THE INVENTION
(10) An inventive chassis 1, on which a body of a rail vehicle (not illustrated), for example a locomotive, is flexibly supported so that it pivots about a vertical axis, has a chassis frame 2 as shown in FIG. 1 and FIG. 2. The chassis frame 2 is supported at least on a first wheel set 3 and a second wheel set 4, which are referred to below jointly as wheel sets 3 and 4. Each of the wheel sets 3 and 4 has two track wheels 5, which are connected by a wheel axle 7 held in two axle bearings 6. For horizontally guiding the axle of the wheel sets 3 and 4, these wheel sets are each hinged to the chassis frame 2 on both sides of the chassis via A-arms 8. Each A-arm 8 is hinged to an axle bearing 6 by a wheel-set-side bearing 9 and to the chassis frame 2 by two frame-side bearings 10. The frame-side bearings 9 have elastomer bushings 11 with constant longitudinal and transverse rigidity and the wheel-set-side bearings 10 have hydraulic bushings with constant transverse rigidity and variable longitudinal rigidity. The bearings 9 and 10 of each A-arm 8 are arranged respectively on the corners of a horizontally aligned isosceles triangle, the tip of the triangle forming the wheel-set-side bearing 9 and the base of the triangle forming the frame-side bearings 10. Unlike the two-axle chassis 1 shown in FIG. 1, a three-axle chassis 1 according to FIG. 2 has a third wheel set 13, which is arranged in the longitudinal direction X between the first wheel set 3 and the second wheel set 4 and is connected to the chassis frame 2. When the rail vehicle travels on a curve the outer wheel sets 3 and 4 are aligned radially to the track curve, as indicated by a dashed/dotted line in FIG. 1 and FIG. 2. For this purpose, the hydraulic bushings 12 have a low longitudinal rigidity at low travel speeds, while at high travel speeds on mainly straight tracks they have a high longitudinal rigidity, which leads to high driving stability.
(11) According to FIG. 3 and FIG. 4, each of the A-arms 8 has a linkage body 14, which has a horizontally extending connection wall 15 via which two smaller link lugs 16 for mounting the elastomer bushings 11 and a larger link lug 17 for mounting the hydraulic bushing 12 are connected to one another. The linkage body 14 may be designed as a cast, forged or milled part. Vertically protruding connecting webs 18 are optionally molded on the two side edges of the connection wall 15 connecting the larger link lug 17 to the smaller link lugs 16. Each elastomer bushing 11 has an inner bearing shell 19, an outer bearing shell 20 and an elastomer ring 21 embedded between them. Due to the rotationally symmetrical design of the elastomer bushing 11 it has a constant rigidity in the longitudinal direction X and in the transverse direction Y. The outer bearing shell 20 sits in the smaller link lug 16, while the inner bearing shell 19 is penetrated by a vertically aligned bearing bolt 22. At both ends of the bearing bolt 22 protruding from the inner bearing shell 19, two flat contact surfaces are carved out, lying parallel to one another, in the region of which a horizontal hole 23 running through is incorporated at each end. The through holes 23 are used for guiding the fixing means 24 for connecting the frame-side bearings 10 to the chassis frame 2 above and below the elastomer bushings 11. Each hydraulic bushing 12 likewise has an inner bearing shell 25, an outer bearing shell 26 and an annular elastomer element 27 embedded between them. The outer bearing shell 26 sits in the larger link lug 17, while the inner bearing shell 25 is penetrated vertically by a bearing bolt 28. The bearing bolt 28 has a vertical hole 29 running through it, through which fixing means 30 are guided for connecting the wheel-set-side bearing 9 to the axle bearing 6 coaxially through the hydraulic bushing 12. The elastomer element 27 and the outer bearing shell 26 form two segment-shaped cavities opposite one another in the longitudinal direction X, whereof the cavity facing the elastomer bushings 11 forms an internally located fluid chamber 31 and the cavity facing away from the elastomer bushings 11 forms an externally located fluid chamber 32. The fluid chambers 31 and 32 are connected to one another by an internal fluid duct 33 and are filled with a hydraulic fluid. This causes the internally and externally located fluid chambers 31 and 32 to be hydraulically coupled such that hydraulic fluid, which flows out of one of the fluid chambers 31 or 32 as a result of external pressurization, flows into the other fluid chamber 32 or 31. The external pressurization originates from guidance forces between the axle bearings 6 of the wheel sets 3 and 4 and the chassis frame 2, which are transmitted by the A-arm 8 and can lead to a fluid exchange between the fluid chambers 31 and 32 in the hydraulic bushings 12.
(12) The frequency f, with which transverse accelerations are externally excited in the elastomer element 27 by the wave travel of the wheel sets 3 and 4, is crucial for the longitudinal rigidity c of the hydraulic bushings 12. As well as high transverse rigidity the hydraulic bushings 12 have a variable, excitation-frequency-dependent longitudinal rigidity c, the course of which is indicated in FIG. 5. Low frequencies f, which occur at low travel speeds of the rail vehicle, for example when traveling on curves, are accompanied by low longitudinal rigidity c.sub.low; the wheel-set-side bearings 9 are then soft, so that a radial positioning of the wheel sets 3 and 4 in the track curve is possible by fluid exchange. At high travel speeds of the rail vehicle when driving straight ahead, high excitation frequencies f occur, which are accompanied by a high longitudinal rigidity c.sub.high; the wheel-set-side bearings 9 are then hard, whereby the driving stability of the chassis 1 is increased. The speed of the fluid exchange between the fluid chambers 31 and 32 is dependent on the flow resistance of the internal fluid duct 33, which is essentially determined by its course and cross-sectional area.
(13) The fluid chambers 31 and 32 are not connected internally in a hydraulic bushing 12 in the embodiment according to FIG. 6, but via external fluid ducts 34, which can be designed as a rigid hydraulic line or as flexible hydraulic tubes. The hydraulic bushings 12 arranged on the same chassis side are connected here via two external fluid ducts 34 such that the externally located fluid chamber 32 of the first wheel set 3 is hydraulically coupled to the internally located fluid chamber 31 of the second wheel set 4 and the internally located fluid chamber 31 of the first wheel set 3 to the externally located fluid chamber 32 of the second wheel set 4. The coupling is affected symmetrically in the longitudinal direction on both sides of the chassis, whereby the radial positioning of the wheel sets 3 and 4 in the track curve is favored and the high longitudinal rigidity c required when starting up with high tractive force or when braking is guaranteed. During start-up or braking of the wheel sets 3 and 4 the forces moving in the same direction are applied to the wheel-set-side bearings 9, so that there is no exchange of fluid between the coupled fluid chambers 31 and 32the response of the bearing 9 is hard. When traveling on curves, forces moving in opposing directions are applied, so that hydraulic fluid is exchanged between the coupled fluid chambers 32 located internally and externally and the soft bearing response may lead to a radial positioning of the wheel sets 3 and 4. The advantage of this concept consists in a good transmission of pull-push forces.
(14) For monitoring of the hydraulic pressure p, according to FIG. 7 and FIG. 8 a pressure sensor 35 is assigned to each pair of fluid chambers 31 and 32 coupled via a fluid duct 33 or 34. The pressure sensor 35 responds when the pressure p prevailing in the hydraulic fluid falls below a pre definable threshold value. When the pressure sensors 35 are connected serially as per FIG. 7, a pressure monitoring device 36 establishes whether there is a critical fall in pressure in the coupled fluid chambers 31 or 32. If the pressure sensors 35 are connected individually to the pressure monitoring device 36 as per FIG. 6, it is possible to establish separately for each pair of coupled fluid chambers 31 and 32 whether there is a critical fall in pressure. The pressure monitoring device 36 is designed to transmit a warning signal to a central control device 37 of the rail vehicle if individual and/or all pressure sensors 35 respond. This makes diagnosis possible in the event of a failure of the hydraulic system. Depending on the finding, a warning signal about the critical fall in pressure can be output to a central control device 37 of the rail vehicle. This enables the operating safety of the rail vehicle to be ensured.
