Patent Application
20100011984
The present invention relates generally to railroad vehicles and particularly to self-steering radial bogies for railroad vehicles.
Radial bogies generally provide railroad vehicles (e.g., unpowered railroad cars and locomotives with motorized axles) the ability to negotiate tight curves through radial adjustment of their wheelsets. The radial adjustment of wheelsets for curve negotiation is generally effected by the longitudinal forces that arise at contact surface points of the wheels as they travel around curves. Such radial adjustability is generally proposed to reduce friction and wear of the wheels and rails by minimizing lateral creep forces.
Traditional radial bogies include a linkage mechanism for providing steering interconnection of the wheelsets. For example, U.S. Pat. No. 6,871,598, incorporated by reference herein and made a part hereof, provides a radial bogie arrangement including an inter-axle link or guide rod which couples the rotation of the steering beam for the leading wheel set with the steering beam of the trailing wheel set. Nevertheless, these steering linkage mechanisms add significant weight and cost to the radial bogie arrangement. Accordingly, it is an object of the present invention to provide a radial bogie arrangement which does not necessitate the use of a steering linkage mechanism.
This and other desired benefits of the preferred embodiments, including combinations of features thereof, of the invention will become apparent from the following description. It will be understood, however, that an arrangement could still appropriate the claimed invention without accomplishing each and every one of these desired benefits, including those gleaned from the following description. The appended claims, not these desired benefits, define the subject matter of the invention. Any and all benefits are derived from the multiple embodiments of the invention, not necessarily the invention in general.
Provided is a self-steering system for a radial bogie of a railroad vehicle. The self-steering system generally includes a plurality of links which connect the leading and trailing wheelsets to the bogie frame. Each of the links is adapted to provide a smaller degree of movement between the link and the wheelset at one end and a larger degree of movement between the link and the bogie frame at the other end. This arrangement provides radial adjustment of the wheelsets during turns. In one embodiment, each of the leading and trailing wheelsets is connected to the bogie frame via a plurality of such links.
The smaller degree of movement is generally achieved by using a relatively stiff bushing situated at one end of the link. The larger degree of movement is generally achieved by using a relatively soft or resilient bushing at the other end of the link. The relatively soft or resilient bushing at the other end of the link may have a progressive longitudinal stiffness over a range of displacement or deflection values. Moreover, the relatively soft or resilient bushing at the other end of the link may have a relatively high vertical stiffness to transfer the vertical component of damper force.
In another embodiment, the self-steering system further includes a damper situated between the second end of the link and the frame of the bogie. The damper provides greater steering efficiency and high stability. In one arrangement, the damper is coupled to the second end of the link.
In yet another embodiment, the self-steering system further includes a link situated between the longitudinally extending side members of the frame. The link connects one of the wheelsets to the frame of the bogie. In one embodiment, the link may be centrally located such that traction and braking forces are transmitted through the centrally arranged traction link, thereby providing a rotational degree of freedom that does not change significantly with traction or braking forces.
Those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiment(s) of the present invention. Also, some parts of the figures are shown in phantom and other parts removed for conveniences of illustration.
The present invention may be embodied in rail trucks or bogies having at least two or more axles or, otherwise, in railroad vehicles having at least two or more powered or unpowered wheel sets. The present invention may further be incorporated in any railroad vehicle (e.g., locomotives or non-driven railroad vehicles).
Referring now to the figures of the drawing in detail and first, particularly, to
Spring elements 8 are provided along the top of the bogie to provide suspension and support for the carbody 4. The spring elements 8 may be either stiff or soft depending on the amount of suspension and support desired for the carbody 4. In one example, the spring elements 8, which could be replaced by any other suitable resilient suspension apparatus, may have a high compression stiffness to provide a relatively stiff secondary suspension between the truck frame and carbody. In another embodiment, the spring elements 8 may yield more freely in shear to permit limited lateral motion as well as yawing motion of the bogie relative to the carbody 4 during normal curve negotiation. Carbody stops 9, provided also along the top of the bogie 2, are arranged to engage inner portions of the carbody 4 to limit the amount of carbody yaw motion as required. Additionally, lateral stops 11 are provided on the bogie 2 to limit the amount of carbody lateral motion as required.
In the illustrated embodiment, elastically suspended from the bogie 2 are a first wheelset 12, a second wheelset 14, and a third wheelset 16. Each wheelset 12, 14, and 16 comprises a first rail engageable wheel 10 and a second rail engageable wheel 18. Left and right wheels 10 and 18 of each wheelset 12, 14, and 16 are support by an axle 20 and are generally parallel and laterally spaced from each other. Additionally, the wheelsets 12, 14, and 16 are also laterally spaced to form longitudinally spaced wheel and axle assemblies. A bearing housing 22 rotatably supports each end of the axle 20 and elastically supports the bogie 2 through wheelset spring elements 24.
The bearing housing 22 may be either a one-piece or a two-piece design. In the one-piece design, the bearing housing 22 is a single piece that encloses the bearing assembly totally (not shown). In the two-piece design, the bearing housing 22 includes upper and lower housing parts. The upper housing provides the interface to the bearing assembly and transfers vertical and horizontal loads. The lower part, or bearing cap/retainer, provides the means of lifting the wheelset with the bearing housing and adds structural strength to the whole assembly.
The wheelset spring elements 24 allow limited relative motion of the wheelsets 12, 14, and 16 with their bearing housings 22 while resiliently urging the housings and their wheel and axle assemblies into nominally centered non-curving longitudinally aligned positions, as is illustrated in
The bogie 2 may be a unitary or assembled/joined frame, and fabricated, cast, or otherwise manufactured. In particular, the bogie 2 includes a pair of generally parallel, laterally-spaced, longitudinally-extending side frames 28 and 30, which for convenience of illustration are shown in dashed lines in
For powering the wheelsets to drive the locomotive embodiment, the bogie 2 is then provided with at least two traction motors 38 or other similar arrangement, one driving each axle 20. In one example as shown, each motor is supported by a conventional bearing arrangement on its respective axle, and is carried from one of the adjacent transoms, via a nose link 40 and/or mounting to respective post 33 or 35. Each nose link 40 is flexibly or swively connected at its ends to allow a limited amount of both longitudinal and lateral motion between the traction motor 38 and the adjacent transom by which it is supported.
Those skilled in the art will recognize that the present bogie arrangements may further include additional components and/or arrangements, such as brakes 42, speed recorder 44, other additional suspension members such as, for example, secondary lateral and yaw dampers, lateral and yaw stops, pitching stops and dampers, and components such as, for example, sand boxes and steps, air ducts, and additional transoms. Such components and others are further disclosed by commonly assigned U.S. Pat. Nos. 4,628,824; 4,679,506; 4,765,250; 4,841,873; 5,613,44; and 5,746,135, which disclosures are herein incorporated fully by reference.
To provide for limited self-steering action of the wheelsets while transmitting traction and braking forces between the wheel and axle assemblies and the bogie frame, the prior art bogie 2 is provided with a traction linkage formed in accordance with the invention. This traction linkage includes laterally-extending leading and trailing steering beams 46 and 48, respectively, which are pivotally connected at their centers with the bottoms of adjacent transoms 32 and 36, respectively. The steering beams 46 and 48 allow the rotation of the end wheelsets relative to the bogie frame.
Laterally opposite ends of the leading and trailing steering beams 46 and 48, respectively, are connected with the bearing housings 22 of the leading and trailing wheelsets 12 and 16 by traction links 50. The steering beams 46 and 48 are attached to upstanding torque tubes 52 which extend vertically upward about a pivot axis 54 of the steering beams and connect, at their upper ends, with a respective one of a pair of crank arms 56. These crank arms 56 extend in laterally opposite directions. The ends of the crank arms 56 are interconnected by an inter-axle link 58 which extends diagonally therebetween over the wheelsets 14 and 16 and the transom 34. In one embodiment, the link 58 may be a unitary component, and in another embodiment illustrated in dashed lines, the link 58 may be segmented or of a split design having first and second links 58a and 58b, which are pivotably supported from the transom 34 by lever arm 60. It is to be appreciated that first and second links 58a and 58b have the same effective length such that the end axles of the leading and trailing wheelsets rotate the same amount.
To support the leading and trailing steering beams 46 and 48 with their associated torque tubes 52 and crank arms 56, the adjacent transoms 32 and 36 are provided with upper pivot plates 62. At the ends of each pair of posts 33 and 35 provided is a lower pivot plate 64, such that the upper and lower pivot plates carrying through bolts 66. Bolts 66 secure bushings 67 on which the torque tubes 52 are pivotally mounted. It is to be appreciated that the traction links are as long as possible to reduce the angular loading on the bushings 67 from respective wheelsets movement in the vertical and lateral directions relative to the bogie frame. Lower angular loading increases life expectancy, reliability, and reduces the contribution of each traction link 50 to the lateral and vertical stiffness of the bogie frame.
The steering beams 46 and 48, traction links 50, cranks 56, and inter-axle link 58 are so arranged as to require equal and opposite yawing (steering) motions of the leading and trailing wheelsets 12 and 16, respectively, so as to provide efficient inter-related self-steering actions of the end axles. These components comprise a first force transmitting linkage which carry the traction and braking forces between the wheelsets and the bogie frame, as well as allowing equal and opposite self-steering of the end wheelsets 12 and 16.
In the prior art system, a pair of yaw dampers 69 is connected to each steering beam 46 and 48 and the bogie frame, one of each pair only shown by
Nevertheless, the self-steering arrangement of the prior art system provides undesirable weight and cost. The prior art self-steering (including steering beams 46 and 48, traction links 50, cranks 56, and inter-axle link 58, yaw dampers 69) of
More specifically, in one embodiment as shown in
As shown in further detail in
The second end 202 is generally connected to the bogie frame 32, 36. The second end 202 generally includes a relatively soft bushing 206 in the longitudinal direction which is adapted to provide a larger degree of movement between the bogie frame 32, 36 and the traction link 150. An example of a suitable bushing is illustrated in
Depending on the application, Zone A ranges from about −2 to +2 mm or up to about −6 mm to +6 mm longitudinal displacement. In this range, the longitudinal stiffness of bushing 206 may be about 0 kN/mm to about 8 to 10 kN/mm. It is preferable that the longitudinal stiffness is about 2 kN/mm to about 4 kN/mm. In Zone B, the bushing 206 has an exponentially increasing longitudinal stiffness ranging from about 4 kN/mm to about 150 kN/mm depending on the maximum deflection. A very high stiffness is provided in Zone C (not shown) to limit the maximum displacement.
For wheel mounted disk brake application which are not sensitive to longitudinal wheel movements or for conventional tread brake systems having a large application stroke, the maximum displacement range extends up (or down) to about ±10 mm. For unitized tread brake systems having a limited application stroke, the displacement range extends up (or down) to about ±5 mm.
The bushing 206 at the second end 202 may be constructed relatively stiff in the vertical direction to transfer the vertical component of damper force. In one embodiment, the bushing 206 at the second end 202 generally has a vertical stiffness of about 20 kN/mm. This arrangement of a bushing having a progressive longitudinal stiffness over a range of displacement and a relatively stiff vertical stiffness provides radial adjustment of the wheelsets during turns. For example, for 3-axle standard gauge bogies (e.g., in North America, Europe, China, etc.) and an axle spacing of around 4000 mm, this arrangement will enhance the self-steering to curves as tight as 500 m to 800 m.
It is to be noted that the bushings 204, 206 may be constructed of any suitable resilient material (e.g., a rubber, polymer, etc.). It is also to be noted that the first end 200 and second end 202 of the traction link 150 may be directly or indirectly connected to any structure coupled to the wheel set or the bogie frame, respectively. Although the traction link 150 is shown to be generally straight in
As further illustrated in
In yet another embodiment as shown in
In yet another embodiment as shown in
In another embodiment, in order to provide steering efficiency and high stability, yaw dampers 469 are further provided. In contrast to the prior art system, the yaw dampers 469 are shown to connect the swing-arm apparatus 450 to the bogie frame at 28 and 30.
As discussed with regards to the various embodiments of the present invention, one end of the traction link is connected to one of the wheelsets to provide a smaller degree of movement therebetween, whereas the other end of the traction link is connected to the frame of the bogie to provide a larger degree of movement therebetween. This may be achieved using various arrangements including, but not limited to the use of bushings. For example, a stiffer bushing may be used in conjunction with the end of the traction link connected to the wheelset, whereas a softer bushing may be used in conjunction with the other end of the traction link connected to the frame of the bogie. Moreover, the stiffness of the traction link itself may be adapted to achieve the teachings of the present invention.
While this invention has been described with reference to certain illustrative aspects, it will be understood that this description shall not be construed in a limiting sense. Rather, various changes and modifications can be made to the illustrative embodiments without departing from the true spirit, central characteristics and scope of the invention, including those combinations of features that are individually disclosed or claimed herein. Furthermore, it will be appreciated that any such changes and modifications will be recognized by those skilled in the art as an equivalent to one or more elements of the following claims, and shall be covered by such claims to the fullest extent permitted by law.
This application claims benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/081,237, entitled “Self-Steering Radial Bogie,” filed Jul. 16, 2008, naming Hans-Dieter Schaller and Xiaoying Ma as inventors, the complete disclosure thereof being incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61081237 | Jul 2008 | US |
