DE29720120U1 - Running gear for rail vehicles - Google Patents

Description

DESCRIPTION

Dipl.-Ing. Michael Kammler 11.11.1997

Brunssumstr. 38
D-52074 Aachen

Chassis for rail vehicles

The invention relates to a chassis according to the preamble 1.

The task of a rail vehicle chassis is to transfer all forces and moments arising from the functions of carrying, guiding and driving/braking from the car body to the contact surfaces of the wheels. The chassis can be assessed according to the criteria of quality of the track guidance (derailment safety), comfort and weight. The exact position of the wheels in the direction of the track is particularly important for the quality of the track guidance. This so-called radial adjustment can be achieved in rail vehicle chassis using three different mechanisms.

• Longitudinal forces are generated in the contact surface (used in every wheelset chassis). The naturally unstable dynamic behavior of the wheelset shaft run can only be shifted to higher speeds by complex constructive countermeasures.

• The wheels are coupled to the position of the car body with lever mechanisms (for example, TALGO articulated train [Patent DE 25 12 008]). Solutions based on this principle are widespread in road vehicle construction. However, the elasticity and traction behavior of the steel wheels used in rail vehicles differs by orders of magnitude from the pneumatic/rubber wheels used in road vehicles. Therefore, solutions based on this principle fail due to the unattainably high precision required for the levers and joints.

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• Transverse forces are generated in the contact surface (should be used here). This principle requires two pairs of wheels arranged one behind the other to generate the necessary lever arm for mutual radial adjustment.

While most conventional chassis (e.g. double wheel set chassis; see Fig. 1) adjust radially using longitudinal forces or lever mechanisms, chassis prototypes have been built in recent years whose radial adjustment is achieved exclusively by transverse forces. Several single-wheel or loose-wheel chassis with a one-piece frame (MB B loose-wheel chassis; DUEWAG/Frederich-EDF [Patent DE 42 21 544]; FIAT/Panagin chassis [DE 30 19 468]; see Fig. 2) have already demonstrated the functionality of this principle extremely successfully. A division of the previously one-piece frame into two half bogies (see Fig. 3) with external pivot points and thus the elimination of the lever arm causing permanent slanting has already been described in the specialist literature (half bogie chassis [ETR (26) 7/8-1977 pp. 517-522; patents DE 30 42 987, EP 0 025 484]).

Conventional bogies, i.e. double wheel set bogies (see Fig. 1), have the following main disadvantages:

• The frame must be very heavy in order to transfer the wheel contact forces of the widely spaced wheel sets into the car body.

• The wheel sets themselves are very heavy, as they carry the unsprung wheel set load (up to over 20 t) over a bearing distance of around 2 to 3.5 metres.

• The wheelset shaft running causes undesirable longitudinal and transverse forces and thus wear.

• The running stability must first be created through complex design measures.

Previously designed chassis with radial adjustment by transverse forces generated in the contact surface are, for example, single-wheel double chassis (see Fig. 2); in

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All the essential design features of conventional bogies were adopted. The one-piece frame construction is particularly worth mentioning here, in which all four wheels rotate around a common pivot point in the middle of the chassis around the vertical axis. However, this one-piece frame principle, which has proven itself for double wheel set bogies, is unnecessary for a single wheel double bogie because there are no longer any wheel sets that absolutely require it for kinematic reasons. Therefore, the following disadvantages still apply to these bogies (see Fig. 2):

• The high weight of the frame remains undiminished.

• If continuous "loose wheel sets" are used, there is no weight advantage compared to conventional wheel sets.

• The highest precision of the wheel position required here cannot be achieved in such a frame due to manufacturing technology.

The principle of the one-piece frame is abandoned for half bogies (see Fig. 3), but the usual large wheelbase of around 2 to 3.5 meters is still used. With conventional, one-piece frame constructions with a common pivot point, extremely short wheelbases were not possible due to tilting with a small length/width ratio ("drawer effect"); in addition, the wheelset bogies required the long wheelbase because of the otherwise inadequate driving stability. Due to the structurally predetermined dissipation of the longitudinal forces far above the top edge of the rail, large wheel load fluctuations can only be reduced by a large wheelbase. This development stage (see Fig. 3) therefore has the following disadvantages:

• The weight and space requirements of the chassis remain high.

• The selected kinematics generate very high forces and moments at the two articulation points of the half bogies. Together with the small installation space and the transmission by bolts or pins, this suggests a weak point in the construction.

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The aim of the invention is to make consistent use of the numerous advantages of single wheels. For this purpose, they are integrated into a chassis concept that is not based on conventional concepts of double wheel sets that are unsuitable for single wheels, but rather meets the requirements and possibilities of single wheels.

This task is solved by a chassis according to the generic term 1.

This chassis therefore consists of a half-bogie solution with defined pivot points (see Fig. 4), which enable the wheelbase to be reduced to values of little more than the wheel diameter and thus a reduction in the cutting moments in the load-bearing frame parts (see Fig. 1-4 above). The main advantages of this new frame design (see Fig. 4) compared to known designs (see Fig. 1-3) are listed below.

• Masses, moments of inertia and installation space are drastically reduced.

The frame is a bending beam whose weight increases disproportionately with length, mainly due to the bending moments that have to be transmitted. The new chassis concept is expected to reduce weight and length by about half.

• The position of the individual wheel pairs is parallel with a previously unknown precision.

Two individual short half bogies can be machined in one setup and achieve values that are orders of magnitude better in terms of parallelism of the two connected wheels than the known designs (which, for this reason, always lagged behind the simulation results). The necessary precise parallelism between the two half bogies is achieved by levers and joints that can be finely adjusted in length.

• This results in a simplified structure.

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The elimination of complex and large components results in a reduction in production costs. The structural separation of the parallel guidance of the frame side parts on the one hand and the connection to the car body on the other enables them to be designed largely as simple and weight-saving pull/pull rods with ball heads and/or elastomer joints.

The recognized advantages of previous contractions (see Fig. 2 and 3) are still fully usable:

• Theoretical considerations, simulation results and implemented prototypes (see Fig. 2) have proven the basic suitability of single wheel concepts for track guidance and in some cases the superiority of this principle over the wheelset concepts.

• Only the half-bogie concept (see Fig. 3) actually guarantees the desired independence of the radial position of the wheel in the track from the longitudinal forces in the wheel/rail contact. While in all other concepts (see Fig. 2) disruptive effects from the moments of inertia of the wheel and motor or from the normal fluctuation of the longitudinal forces are still present, here the responsible lever arm between the center of rotation around the vertical axis and the wheel/rail contact point is not present and the chain of effects is therefore interrupted.

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The following advantages can be expected in practice:

• The typical advantages of single-wheel chassis, especially smooth running at high speeds and low wear, can be fully utilized for the first time.

• The longitudinal running free of forced slip allows the transmission of increased traction and braking forces.

• Despite the short wheelbase, the pivot point at the top of the rail does not produce any dynamic wheel load fluctuations during acceleration or braking and therefore makes expensive countermeasures to prevent skidding or blocking unnecessary.

• Unlike other concepts, there are no dampers or even controls, if they fail, the dynamic stability of the chassis is lost.

• The elimination of the wheelset shaft, the use of small wheels and a fundamentally free lever arrangement makes the use of the chassis concept in low-floor vehicles and freight wagons for combined transport possible without any problems.

The extremely short wheelbase produces only small approach angles even with very tight radii and makes it possible to use it on urban trains and trams.

• The elimination of the shaft run typical of wheelsets in combination with extremely low mass inertia and moments of inertia enables the safe transmission of very high transverse forces and thus the use in tilting trains with high transverse dynamics.

• The low masses and the track guidance dynamic stability predestine the concept for use in high-speed trains.

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The low masses and moments of inertia as well as the inherently smooth running protect the track bed and thus reduce maintenance costs for the vehicle and the track.

Due to the extremely short wheelbase, not only is there a significant saving in mass but there is also a significant saving in installation space.

Elements of an existing modular system such as brakes and tilting technology can still be easily combined.

The use of small wheels at high speeds makes direct drive possible, thus eliminating the need for expensive and heavy transmissions.

The connecting rods to the car body do not require a high level of precision (unlike the Talgo, for example) and can therefore be made with elastomer elements to avoid structure-borne noise transmission.

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Embodiments of the invention are shown in the drawings and are described in more detail below. They show

Figure 1-4: Comparison of the chassis concepts in terms of structural design (middle), cutting moments in the frame (top) and kinematics (bottom):

1) Bogie or double axle bogie (state of the art).

2) Prototypes designed as single-wheel twin chassis (state of the art).

3) previously proposed semi-bogie chassis (state of the art).

4) described chassis concept.

Figure 5: Examples of chassis designs in side view.
Figure 6: Examples of chassis designs in front view.
Figure 7: Examples of chassis design in top view.

Figure 8: Parallel lever mechanism using two articulated or torsionally elastic square levers.

Figure 9: Parallel lever mechanism using two triangular levers.

Figure 10: Parallel lever mechanism using two rods and a centrally located hinged or torsionally flexible support.

Figure 11: Parallel lever mechanism using three rods and a stabilizer.

A first lever mechanism is responsible for introducing transverse forces and ensuring the precise parallel guidance of the two half bogies F at the track width distance. The free movement of the two half bogies F around their vertical and transverse axes enables radial adjustment and the travel over track twists.

In the solution variant according to Fig. 8, square levers H mounted in joints G support one frame side part F on the other. The half bogies or the square levers are designed to be torsionally flexible or articulated in order to allow the chassis to twist when traveling over twisted tracks.

Another variant according to Fig. 9 avoids the use of torsionally soft or articulated components. Here, triangular levers H mounted in joints G support one frame side part F on the other. This allows forces from the transverse direction to be absorbed without limiting the torsional capacity. The torsion of the chassis for traveling over twisted tracks is thus achieved by pivoting the two halves around the diagonal V.

Another variant according to Fig. 7 uses a centrally located torsionally flexible or articulated support M to absorb the transverse forces and one or two off-center bars for parallel guidance.

The schematic diagram of another solution variant is shown in Fig. 11. The separate half bogies F each have three articulation points G , which are connected to the three transverse rods S. The use of a stabilizer element (spring) is necessary in order to limit possible pivoting movements around the longitudinal axis in the event of forces occurring from the transverse direction.

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* With

A second lever mechanism enforces the defined position of the pivot poles D and thus makes the integration of these extremely compact half bogies into a rail vehicle possible.

To ensure that longitudinal forces cannot exert any disruptive moments around the vertical axis on the half bogies, the pivot point for pivoting around the vertical axis must be located on the direct connection between the two running circles of the two wheels of a half bogie. The pivot point for pivoting around the transverse axis must be at the level of the top edge of the rail in order to avoid fluctuations in the wheel loads caused by longitudinal forces.

This is solved by a kinematics which creates a position of the center of rotation in the middle of the connecting line of the two wheel contact points of a half bogie.

Two possible implementations with a structural design of the kinematics as a four-bar linkage for two different installation situations and two different arrangements of the tension/compression rods Z are shown as examples in Figures 5, 6 and 7 in all three views.

Push/pull rods Z point from these ideal pivot points D to the car body/the two adjacent car bodies either outside (see Fig. 5, 6 and 7 above) or inside (see Fig. 5, 6 and 7 below) past the wheels. A mechanism L attached to the half bogies enables the necessary length compensation when the vehicle is compressed and when cornering or driving on ramps. It also holds the chassis both centrally and at right angles to the bisector between the two car bodies (see Fig. 5, 6 and 7 above) W or parallel under a single car body (see Fig. 5, 6 and 7 below). In the installation case according to Fig. 5, 6 and 7, longitudinal forces within the car body are transferred directly from body to body at pivot point K. This is supported springily on the two half bogies.

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Claims (12)

EXPECTATIONS 1. Chassis concept for rail vehicles consisting of two half bogies F, each connecting both individual wheels E of one side, characterized in that the two half bogies F are guided parallel to the track width by a first device and their tilting movement about the vehicle's longitudinal axis is prevented, and characterized in that the two half bogies F are forced by a second device in their pivoting movement about the vertical and transverse axes to individual pivot points D, which are located in the middle of the connecting line of the wheel contact points of one side, whereby the previously impossible, extremely compact and lightweight design of the load-bearing frame parts becomes possible (see Fig. 4). 2. Chassis concept according to claim 1, characterized in that in each case a A lever mechanism Z (consisting of two rods) generates imaginary rotational poles D and the length compensation required for transverse and vertical movements is realized by a mechanism L, whereby the transverse axis of the chassis is always parallel under a car body or in the bisector of two car bodies (see Fig. 5, 6 and 7). 3. Chassis concept according to claim 1, characterized in that two square levers H hold the two torsionally flexible or articulated half bogies F parallel (see Fig. 8). 4. Chassis concept according to claim 1, characterized in that two torsionally flexible or articulated square levers H hold the two half bogies F parallel (see Fig. 8). 5. Chassis concept according to claim 1, characterized in that two three- -11- Corner lever H holds the two half bogies parallel (see Fig. 9). 6. Chassis concept according to claim 1, characterized in that a centrally located either articulated or torsionally flexible frame middle part M supports the two half bogies against each other, while they are guided parallel by two rods (see Fig. 10). 7. Chassis concept according to claim 1, characterized in that three rods 5 hold the two half bogies F parallel (see Fig. 11). 8. Chassis concept according to one of the preceding claims, characterized in that the car body is supported by springs on unsprung half bogies (see Fig. 5, 6 and 7). 9. Chassis concept according to one of the preceding claims, characterized in that a cross member rests on the half bogies F via springs, which transmits the forces via the joint K to the car bodies W. 10. Chassis concept according to one of the preceding claims, characterized in that the car body is supported on half bogies F , which are designed as integral components with suspension function. 11. Chassis concept according to one of the preceding claims, characterized in that wheel constructions with integrated suspension and damping are used as individual wheels. 12. Chassis concept according to one of the preceding claims, characterized in that individual wheels E of this chassis are driven individually or in groups. -12-