Bogies for rail vehicles
This application is a continuation-in-part of Ser. No. 08/071,180, filed Jun. 2, 1993, and now U.S. Pat. No. 5,335,602, which was in turn a continuation of Ser. No. 07/842,052, filed Feb. 26, 1992, and now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to bogies for rail vehicles. The invention is especially applicable to driven bogies. These driven bogies comprise a bogie frame, typically comprising longitudinal and lateral beams; two or more wheelset units, which may include a drive unit and/or brake unit, connected to the bogie frame via a primary suspension, or a linkage and a primary suspension; and a secondary suspension, or a center pin or similar device and a secondary suspension, for connecting the bogie frame to a car body. 
     For such bogies, it is desirable that the wheelsets adjust themselves on a curved track. How readily they do so depends on the longitudinal stiffness of the primary wheelset linkage or suspension. A large number of such bogies with radially adjustable wheelsets have been disclosed. With the majority of these bogies, as disclosed, for example, in German patent specifications DE 31 19 164 C2 and DE 32 32 289 A1 and WIPO patent specification WO 90/02068, which are incorporated herein by reference, more or less rigidly linked coupling mechanisms are used. These coupling mechanisms are arranged between the wheelsets or between the wheelsets and the car body. The mechanical coupling of a wheelset to a drive unit, which--because the coupling elements are so arranged--allows the wheelset to swivel about a pivoting point, is also known. This pivoting point can be ideal or real, and it can be situated before or behind the wheelset, &#34;before&#34; and &#34;behind&#34; being defined with respect to the direction of travel. Also, indirect mutual support of axle drives in conjunction with wheelset coupling elements is disclosed in European patent application 0 072 535 A1, incorporated herein by reference. 
     Because they are made up of many components, these known bogies are costly to assemble and to maintain, and they require close tolerances. 
     The wheelsets of some bogies can be more or less freely adjusted, because their primary linkage has very low longitudinal stiffness. However, since the primary linkage must also transfer the tractional forces during starting and braking, the forces adjusting the wheelset are interfered with or compensated for. The resulting parallel displacement of the wheelset must be limited because of the inherent geometry of the drive and the brake. This approach also results in limiting the mutually opposed longitudinal travels of the primary linkage required for wheelset adjustment. 
     When wheelsets are driven by drive motors or power takeoffs suspended from the car body, via a drive shaft and axle drive, a turn-out movement of the bogie requires the drive shaft, which is arranged between the vehicle body and the bogie, to change its length (EP 0 072 535). 
     When drive momentum is transferred during an inward or outward curve, a change in length requires extension forces. These extension forces can increase the turn-out resistance of the bogie several times and--especially at high rates of drive performance--hamper or make impossible the free adjustment of the bogie in the curve. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to eliminate or at least mitigate the foregoing deficiencies and create an improved bogie, in particular, a traction bogie. 
     Briefly, a bogie for rail vehicles, in particular a driven bogie, with a bogie frame, includes two or more wheelset units which comprise at least one drive unit and/or brake unit. The wheelset units are connected to the bogie frame by a primary suspension. A secondary suspension connects a vehicle body with the bogie frame. A rigid connecting link extends from at least one of the wheelset units to connect the bogie to the vehicle body. The rigid connecting link is coupled to the wheelset unit at its virtual center of rotation. Where practical, the center of rotation and the center of mass coincide, to minimize the moment of inertia of the wheelset units. 
     According to the present invention a bogie for rail vehicles comprises a bogie frame, two or more wheelset units, at least one of the wheelset units comprising at least one of a drive unit, a brake unit, and a wheelset coupling frame connected thereto, a primary suspension connecting the wheelset units to the bogie frame, a secondary suspension for connecting a vehicle body to the bogie frame, and a rigid guide rod for coupling between the bogie and a vehicle body, the guide rod being coupled at its one end to one of the wheelset unit&#39;s components at, or as close as possible to, a center of rotation or virtual center of rotation thereof. 
     Such coupling at, or as close as possible to, the center of rotation or virtual center of rotation of the wheelset or drive unit helps to reduce or eliminate parasitic moments when traction forces are applied as the vehicle travels around a curve. Such parasitic moments lead to maladjustment of the wheelsets. Such maladjustment in turn leads to higher frictional losses and lower stability at high speed. Parasitic moments are reduced or eliminated because the coupling through which traction forces are applied generates no moment in the wheelset, leaving the wheelset free to accomodate easily to the curve of the track. 
     Ideally, the center of rotation should coincide with a vertical axis passing through the center of mass of the wheelset. Such an arrangement minimizes the moment of inertia about the center of rotation for a given distribution of mass in the wheelset. Minimizing the center of mass about the center of rotation permits the wheelset unit to adjust as quickly as possible to changes in track curvature. Such responsiveness also reduces frictional losses between the wheels and the track and enhances stability. 
     Advantageously, in embodiments of the invention, the transmission of the traction forces is such that the wheelsets are allowed only a certain adjustment behavior. This behavior is determined by forces arising from the interaction of the wheels with the track. The bogie frame is left to perform only &#34;carrying&#34; and &#34;guiding&#34; functions. Advantages of bogies embodying the present invention include ease of assembly and maintenance and loose tolerances in manufacturing. 
     It is advantageous to have the guide rod flexibly mounted in non-wearing elastomeric elements capable of withstanding cardanic stress, so that the longitudinal forces can be transferred without being controlled. 
     In the case of non-driven wheelsets, coupling can be established via a centrally arranged bearing or via a bifurcated shaft coupled to the wheelset bearings. In the case of driven wheelsets, the guide rod can be coupled close to the centre of gravity of a drive unit elastically or rigidly connected to the wheelset. 
     Coupling of the wheelsets can be established individually or in such a way that both wheelsets are coupled to each other inside the bogie, and a common coupling is made via the guide rod to the vehicle body. In this case, two wheelsets, for example, can be coupled in such a way that the adjustment behavior of the individual wheelsets is not affected, or a specific radial adjustment of both wheelsets, e.g., via a common central linkage point, can be achieved. 
     Embodiments of the invention make it possible to neutralize the traction moments that occur during starting or braking, especially in bogies where axle suspension motors or drives are elastically supported on both sides of the wheel or on the wheelset shaft. To ensure that the turning movements of the wheelsets are not interfered with by the rigidly or transversely elastically mounted drive or brake units, the latter are advantageously suspended from the main cross beam of the bogie via pendulums. 
     Some embodiments of the invention link at least two wheelsets and transmit traction forces via a common coupling. In such embodiments, a sufficiently soft design of the lateral characteristic of the common coupling and of the primary wheelset linkage allows the wheelsets to yield individually, as when evading lateral disturbances, without transferring the forces generated between the wheelsets. 
     If the arrangement of a single central coupling point in conjunction with the longitudinal stiffness of the linkage at the wheelset bearing is not enough to achieve a higher speed through stable travel, paired coupling points or elements can permit the wheelsets to turn independently. The maximum speed can be further increased, according to the present invention, by combining a coupling frame which connects all wheelset bearings at defined rates of elasticity and which facilitates the use of fully elastic quill drives. 
     In the case of vehicles driven by a drive shaft and an axle drive, the coupling is arranged parallel to the drive shaft, with the guide rod having the same length as the drive shaft between the universal joint centers. This arrangement eliminates any change in length during outward-turning of the bogie. It is practical to integrate the momental support required at the axle drive into a bifurcated guide rod. The guide rod connecting two adjacent axle drives may be designed similarly. 
     According to an embodiment of the present invention, a bogie tier a rail vehicle comprises: a bogie frame having a center, wheelset units, at least one of the wheelset units having one of a drive unit and a brake unit, a primary suspension for connecting the wheelset units to the bogie frame, the rail vehicle having a body, a secondary suspension for connecting the body to the bogie frame, a rigid member having a first end and a second end, the first end having first means for coupling the rigid member to the body, each of the wheelset units having a console extending horizontally toward the center, the second end having second means for coupling the rigid member to at least one of the consoles, and means for interconnecting at least two of the consoles. 
     According to another embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame having a center, wheelset units, a coupling frame positioned substantially between two of the wheelset units, the coupling frame including means for mechanically coupling the two wheelset units, the means for mechanically coupling including means for transmitting tractional forces between the two wheelset units, a primary suspension for connecting the wheelset units to the bogie frame, the rail vehicle having a body, a secondary suspension connecting the body to the bogie frame, a rigid member having a first end and a second end, the first end having first means for coupling for joining the rigid member to the vehicle body and the second end of the rigid member having second means for coupling for joining the rigid member to the coupling frame. 
     According to yet another an embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame having a center; wheelset units; at least one of the wheelset units including one of a drive unit and a brake unit; a primary suspension for connecting the wheelset units to the bogie frame; the rail vehicle having a body; a secondary suspension for connecting the body to the bogie frame; a rigid member having first, second, and third positions thereon; each of the wheelset units having a console extending horizontally toward the center; means for cardanically interconnecting at least two of the consoles; first means for coupling for coupling the rigid member to the body at the first position; second means for coupling for coupling the rigid member to the one of a drive unit and a brake unit at the second position; and third means for coupling for coupling the rigid member to one of the at least two consoles. 
     According to yet another embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame having a center, wheelset units, at least one of the wheelset units including one of a drive unit and a brake unit, the one of a drive unit and a brake unit having a virtual pivot axis, a primary suspension for connecting the wheelset units to the bogie frame, the rail vehicle having a body, a secondary suspension for connecting the body of the rail vehicle to the bogie frame, a rigid member having a first end and a second end, the first end having first means for coupling for coupling the rigid member to the vehicle body, the second end having second means for coupling for coupling the rigid member to the one of a drive unit and a brake unit substantially on the virtual pivot axis, each of the wheelset units having a console extending horizontally toward the center, means for interconnecting the consoles of at least two different ones of the wheelset units, at least one first pendulum having forward and rear ends, a first coupling on the forward end for connecting the forward end to the bogie frame, and a second coupling on the rear end for connecting the rear end to the console of one of the at least two different wheelset units. 
     According to yet another embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame, wheelset units, each of the wheelset units including one of a drive unit and a brake unit, the one of the drive unit and the brake unit having a virtual pivot axis, a vertical line passing through the virtual pivot axis, a primary suspension connecting the wheelset unit to the bogie frame, the rail vehicle having a body, a secondary suspension for connecting the body of he rail vehicle to the bogie frame, a rigid member having a first end and a second end, the first end of the rigid member having first means for coupling the rigid member to the vehicle body, the second end of the rigid member having second means for coupling the rigid member to one of the drive unit and the brake unit of a first of the wheelset units at a point substantially on the vertical line passing through the virtual pivot axis, each of the wheelset units having an inside console extending substantially horizontally and substantially toward the center, means for interconnecting the inside consoles of at least two different wheelset units, at least one pendulum having first and second ends, a first pendulum coupling on the first end of the at least one pendulum for connecting the first end of the at least one pendulum to the bogie frame, and a second pendulum coupling on the second end of the at least one pendulum for connecting the second end of the pendulum to the console of one of the at least two different wheelset units. 
     According to yet another embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame, wheelset units, each of the wheelset units including one of a drive unit and a brake unit, a primary suspension for connecting the wheelset units to the bogie frame, the rail vehicle having a body, a secondary suspension for connecting the body of the rail vehicle to the bogie frame, a rigid member having a first end and a second end, the first end of the rigid member having first means for coupling for cardanically coupling the rigid member to the vehicle body, the second end of the rigid member having second means for coupling for coupling the rigid member to one of the drive unit and the brake unit of a first of the wheelset units, the first of the wheelset units having a virtual pivot axis, the first means for coupling including means for coupling the rigid member at a point substantially on the virtual pivot axis, each of the wheelset units having an inside console extending substantially horizontally and substantially toward the center, means for interconnecting the inside consoles of at least two different wheelset units, at least one pendulum having first and second ends, a first pendulum coupling on the first end of the at least one pendulum for connecting the first end of the at least one pendulum to the bogie frame, and a second pendulum coupling on the second end of the at least one pendulum for connecting the second end of the at least one pendulum to the console of one of the at least two different wheelset units. 
     According to yet another embodiment of the present invention, a bogie for a rail vehicle comprises: a bogie frame, wheelset units, each of the wheelset units including one of a drive unit and a brake unit, a primary suspension for connecting the wheelset units to the bogie frame, the rail vehicle having a body, a secondary suspension for connecting the body of the rail vehicle to the bogie frame, a pair of rigid members each having a first end and a second end, the first end of each of the pair of rigid members having first means for coupling for cardanically coupling each of the pair of rigid members to the vehicle body, the second end of each of the pair of rigid members having second coupling means for coupling to one of the drive unit and the brake unit of a respective one of the wheelset units, each of the respective ones of the wheelset units having a virtual pivot axis, each of the first means for coupling including means for coupling a respective one of the pair of rigid members at a point substantially on the virtual pivot axis, each of the wheelset units having an inside console extending substantially horizontally and substantially toward the center, at least one pendulum having first and second ends, a first pendulum coupling on the first end of the at least one pendulum for connecting the first end of the at least one pendulum to the bogie frame, and a second pendulum coupling on the second end of the at least one pendulum for connecting the second end of the at least one pendulum to the console of one of the at least two different ones of the wheelset units. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings. 
     FIG. 1 is a schematic view of a bogie in which a guide rod is coupled to one of two wheelsets. 
     FIG. 2 is a schematic view of a bogie in which a guide rod is coupled to a coupling frame uniting all wheelset bearings. 
     FIG. 3 is a schematic view of another embodiment of a bogie in which a guide rod is coupled to one of two wheelsets. 
     FIG. 4 is a schematic view of a bogie in which guide rods are coupled to respective ones of two wheelsets. 
     FIG. 5 is a schematic view of a bogie in which the guide rod is coupled between a console and a striker arm connected with a center pin. 
     FIG. 6 is a schematic view of a bogie with a coupling frame in which a guide rod is coupled between the coupling frame and a striker arm connected with a center pin. 
     FIG. 7 is a schematic view of another embodiment of a bogie, in which a guide rod is arranged between a console and a striker arm connected with a center pin. 
     FIG. 8 is a schematic view of another embodiment of a bogie with a drive via a drive-shaft and a guide rod coupled to one wheelset. 
     FIG. 9 is a schematic view of a bogie with a drive via drive shafts to two wheelsets and a guide rod coupled to one wheelset. 
     FIG. 10 is a top view of the embodiment or a bogie according to FIG. 3. 
     FIG. 11 is a lateral view of the bogie according to FIG. 10. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a bogie comprises two wheelsets 1 and 2. Connected respectively to wheelsets 1 and 2 are drive units 3 and 4, which are in turn connected to each other via respective inward facing, i.e., mutually opposed, consoles 5 and 6 and a rigid connecting rod 7 for transferring tractional forces. A guide rod 8 is arranged between drive unit 3 and the vehicle body (not shown). For stabilization, drive units 3 and 4 are suspended on pendulums 9, 10, 11, 12 linked to consoles 5 and 6 and the bogie frame (not shown). All linkages are cardanic. The drive units, shown schematically in FIG. 1, can also be brake units, a combination of a drive unit and a brake unit, or a pair of combination drive/brake units. 
     Referring to FIG. 2, a bogie includes a coupling frame 13 that connects the wheelset bearings of wheelsets 1 and 2. Drive units 3 and 4 are provided respectively with inward-facing consoles 5 and 6 and outward-facing consoles 17 and 18. Drive units 3 and 4 are connected to the bogie frame (not shown) by pendulums 9, 10, 11, 12 linked to consoles 5 and 6 and pendulums 15 and 16 linked to consoles 17 and 18. Where the connections of the individual wheelset bearings converge, coupling frame 13 is provided with an upright link rod 14, to which guide rod 8, whose other end is connected to the vehicle body (not shown), is linked. 
     Referring to FIG. 3, in another embodiment, two wheelsets 1 and 2 have drive units 3 and 4 and inward-facing consoles 5 and 6. Consoles 5 and 6 are linked directly to each other so that no connecting rod is necessary to transfer the tractional forces. In this embodiment, only two pendulums 9 and 11 are provided between consoles 5 and 6 respectively and the bogie frame (not shown). Guide rod 8 is arranged between drive unit 3 of wheelset 1 and the vehicle body (not shown). 
     Referring to FIG. 4, another embodiment has two separate linkages. Two wheelsets 1 and 2, with respective drive units 3 and 4 and inward-facing consoles 5 and 6, and pendulums 9, 10, 11, and 12, between consoles 5 and 6 and the bogie frame (not shown), are not connected to each other. Since tractional forces are not transmitted directly between wheelsets 1 and 2, a pair of guide rods 8 and 19 connect drive units 3 and 4 respectively with the vehicle body (not shown). In the case of bogies in which only one wheelset is provided with a drive or brake unit, there would be--as in this embodiment--no connection between the two wheelsets and the guide rod on the non-driven or non-braked wheelset. 
     Referring to FIG. 5, in another embodiment of the invention, the bogie has two wheelsets 1 and 2; provided respectively with drive units 3 and 4 and inward-facing consoles 5 and 6, to which pendulums 9, 10, 11 and 12 are linked and connected with the bogie frame (not shown). Consoles 5 and 6 are connected with each other via a connecting rod 7. A guide rod 20 is coupled at one end to console 5 of wheelset 1 and at the other end to a striker arm 21. Striker arm 21 is connected to a center pin 22 of the vehicle body (not shown). 
     Referring to FIG. 6, another embodiment of a bogie is provided with a coupling frame 13, consoles 5, 6, 17, and 18, and pendulums 9, 10, 11 and 12, as described above with reference to FIG. 2. Guide rod 20 is linked at one end to coupling frame 13 where the connections to the individual wheelset bearings converge. At its other end, guide rod 20 is linked to striker arm 21 connected to center pin 22 of the vehicle body (not shown). 
     Referring to FIG. 7, a bogie with two wheelsets 1 and 2 has drive units 3 and 4 connected to each other by inward-facing consoles 5 and 6 respectively. Here guide rod 20 is linked at one end to console 5 and at its other end with striker arm 21, which engages center pin 22 of the vehicle body (Not shown). In this embodiment, the suspension of drive units 3 and 4 is accomplished via single pendulum 9 arranged between an upright extension 23 of guide rod 20 and the bogie frame (not shown). 
     Referring to FIG. 8, a bogie comprises two wheelsets 1 and 2. Wheelset 1 is driven by a drive shaft 24 and an axle drive 27. Guide rod 20 is linked to driven wheelset 1 and extends substantially parallel to drive shaft 24. Axle drive 27 is embraced castor-fashion above and below by a bifurcated extension 28 of guide rod 20, whereby guide rod 20 is linked above and below to axle drive 27, thus integrating the torque support for axle drive 27. At its other end, guide rod 20 is linked to the vehicle body (not shown). 
     Referring to FIG. 9, the bogie of FIG. 8 now has second wheelset 2 also driven by a second drive shaft 26 arranged between axle drive 27 of wheelset 1 and an axle drive 30 of wheelset 2. Guide rod 20 is connected to axle drive 27 of first wheelset 1 as illustrated in FIG. 8. A connecting rod 25, extending between axle drive 27 of first wheelset 1 and axle drive 30 of second wheelset 2, transfers the tractional forces. A bifurcated extension 29 of connecting rod 25 embraces second axle drive 30 in like manner to that illustrated in FIG. 8 for guide rod 28. 
     Referring to FIGS. 10 and 11, the bogie of FIG. 3 with only single pendulum 9 has two wheelsets 1 and 2, each with wheels 33. Wheelsets 1 and 2 are connected to a bogie frame 37 via wheelset bearings 42 and primary springs 38. Also between bogie frame 37 and the vehicle body (not shown) are secondary springs 39. Both wheelsets 1 and 2 are provided with drive units, namely, axle-mounted motors 32, and brake units 31. On their housings, axle-mounted motors 32 are provided with consoles 5 and 6 respectively. Consoles 5 and 6 face toward the middle of the bogie and are connected to each other via a cardanic coupling 34. Console 5 has a cardanic linkage 35 to which pendulum 9 is linked. At its other end, pendulum 9 is linked to bogie frame 37 via a cardanic linkage 36. Finally, guide rod 8 is connected at one end to axle-mounted motor 32 of first wheelset 1 via a cardanic joint 40 and at its other end to the vehicle body (not shown) via a cardanic joint 43. That is how tractional forces are transferred directly to the vehicle body by wheelsets 1 and 2 via consoles 5 and 6 (connecting wheelsets 1 and 2 to each other) or via guide rod 8. This configuration permits the adjusting behavior of the wheelsets to be determined solely by the forces of the wheel/track geometry, while the bogie frame performs only &#34;carrying&#34; and &#34;guiding&#34; functions.