RAIL VEHICLE HAVING INCREASED SIDE-WIND STABILITY

Abstract

The invention relates to a rail vehicle, for which a direction of travel is specified and which has a leading bogie at a front of the rail vehicle with respect to the direction of travel and a trailing bogie at the end of the rail vehicle which is directed counter to the direction of travel. The leading bogie and the trailing bogie are each equipped with an anti-roll stabilizer. The roll stiffnesses of the anti-roll stabilizers of the leading bogie and of the trailing bogie are selected to be different such that, when side wind acts on the rail vehicle, unequal wheel unloading at the leading and trailing bogies is counteracted.

Claims

1-7. (canceled)

8. A rail vehicle, comprising: a direction of travel defining a front end of the rail vehicle facing in the direction of travel and an end of the rail vehicle facing counter to the direction of travel; a leading bogie at said front end and a trailing bogie at said end facing counter to the direction of travel, said leading bogie and said trailing bogie each being equipped with a respective anti-roll stabilizer; said anti-roll stabilizers of said leading bogie and said trailing bogie having different roll stiffnesses, causing unequal wheel unloading on said leading and trailing bogies to be counteracted when the rail vehicle is subjected to a side wind.

9. The rail vehicle according to claim 8, wherein said roll stiffnesses of said anti-roll stabilizers of said leading and trailing bogies cause minimal wheel unloading on said leading and trailing bogies when the rail vehicle is subjected to a side wind.

10. The rail vehicle according to claim 8, wherein said roll stiffness of said anti-roll stabilizer of said leading bogie is less than said roll stiffness of said anti-roll stabilizer of said trailing bogie.

11. The rail vehicle according to claim 8, wherein said anti-roll stabilizers of said leading and trailing bogies are each configured as secondary anti-roll stabilizers each being disposed between a car body of the rail vehicle and a respective bogie.

12. The rail vehicle according to claim 8, wherein said anti-roll stabilizers of said leading and trailing bogies have torsion bars with differing torsional stiffnesses, implementing said different roll stiffnesses of said anti-roll stabilizers of said leading and trailing bogies.

13. The rail vehicle according to claim 8, wherein said leading and trailing bogies each have a respective bogie frame and a respective lever with differing lengths disposed between said torsion bar and said bogie frame of each of said anti-roll stabilizers, implementing said different roll stiffnesses of said anti-roll stabilizers of said leading and trailing bogies.

14. The rail vehicle according to claim 8, wherein said anti-roll stabilizers of said leading and trailing bogies have an overall roll stiffness corresponding to an overall roll stiffness of said leading and trailing bogies having identical roll stiffnesses without taking into account an effect of a side wind on the rail vehicle.

Description

[0014] Exemplary embodiments of the invention will now be explained in more detail with reference to the accompanying drawings in which:

[0015] FIG. 1 shows a perspective view of a car body of a rail vehicle

[0016] FIG. 2 shows a perspective view of a leading bogie of the rail vehicle according to FIG. 1,

[0017] FIG. 3 show a perspective view of a trailing bogie of the rail vehicle according to FIG. 1, 6

[0018] FIG. 4 shows a side view of the leading bogie of the rail vehicle of FIG. 1,

[0019] FIG. 5 shows a top view of the bogie according to FIG. 4,

[0020] FIG. 6 shows a perspective view of part of an antiroll stabilizer of one of the bogies of the rail vehicle according to FIGS. 1 and

[0021] FIG. 7 shows a perspective view of a lever arm of the anti-roll stabilizer of FIG. 6.

[0022] As an example of a rail vehicle with improved side-wind stability, FIG. 1 shows a front/leading end car of a multiple unit, said car comprising a car body 1, a leading bogie and a trailing bogie 3, wherein both bogies are designed as internally mounted bogies. FIG. 1 also shows the forces and moments acting on the car body 1 that are generated when the car body 1 is subjected to side wind, e.g. a lateral gust. A lateral force FW, y acts at the height of the top of the rail and thus produces a moment about the wheel-rail contact points of the bogies 2, 3.

[0023] The wind gust also produces a roll moment MW, x (rotation about the vehicle's longitudinal axis). This roll moment MW, x causes unloading on the windward-side wheels of the bogies 2, 3.

[0024] The rail vehicle's direction of travel is indicated by an arrow R.

[0025] In addition, a vertical force FW, z resulting from the application of side wind causes lifting of the car body 1 and, associated therewith, additional unloading of all the wheels of the bogies 2, 3. As well as the lifting described above (vertical force FW, z) and the roll moment MW, x, the wind acting laterally on the car body 1 also causes a significant moment MW, z about the vertical axis of the car body 1. This yaw moment MW, z acting on the car body 1 must be balanced by a force couple FMz, h and FMz, v at a connection between the car body 1 and the bogies 2, 3, cf. FIGS. 2 and 3. This force couple causes additional wheel unloading on the leading bogie 2 and reduced wheel unloading on the trailing bogie 3. This in turn means that the leading bogie 2 is more critical in terms of wheel unloading than the trailing bogie 3. A critical average wheel unloading of 90% is achieved on the leading bogie at significantly lower wind speeds than on the trailing bogie 3.

[0026] The bogies 2 and 3 have different roll stiffnesses in order to achieve improved side-wind stability of the car body 1. This will be explained in more detail below.

[0027] The bogies 2, 3 are each equipped with an anti-roll stabilizer 4, 5. The stiffness of the anti-roll stabilizer 4 of the leading bogie 2 differs from the stiffness of the antiroll stabilizer 5 of the trailing bogie 3 in being less than that of the anti-roll stabilizer 5 of the trailing bogie 3.

[0028] The design and operation of the anti-roll stabilizers 4, 5 will now be explained in more detail with reference to FIGS. 4 and 5. The anti-roll stabilizers 4, 5 are so-called secondary anti-roll stabilizers, which are articulated on one side to the car body 1 of the rail vehicle and on the other side to a bogie frame 6 of the bogie 2.

[0029] FIGS. 4 and 5 show, by way of example, the leading bogie whose anti-roll stabilizer 4 basically operates in the same way as the anti-roll stabilizer 5 of the trailing bogie 3. As will be explained later, measures have been taken solely to achieve different roll stiffnesses of the antiroll stabilizers 4 and 5, with the basic design of the anti-roll stabilizers 4, 5 remaining unchanged.

[0030] The anti-roll stabilizer 4 has a torsion bar 7, said torsion bar 7 being rotationally mounted on the car body, namely by means of two rotary bearings 8 which are attached to the underside of the car body 1. By means of horizontal lever arms 9 and vertical lever arms 10, the torsion bar 7 is articulated to the bogie frame 6 via a bogie-side bearing 11.

[0031] In the event of uniform compression of secondary springs 12 of the car body 1 on both sides of the vehicle, the torsion bar 7 rotates within the bearings 8, and no moment is generated. However, if a rolling motion of the car body 1 occurs, i.e. rotation of the car body 1 about its longitudinal axis, uneven compression arises on both sides of the car body 1. This causes the torsion bar 7 to twist, thereby counteracting the rolling motion of the car body 1.

[0032] FIG. 6 illustrates the forces FWa,l and FWa,r acting on the car body 1 that support the roll moment on the car body. This roll moment MW can be calculated via

[00001]$\begin{array}{cc}{M}_W={}_W{c}_T\frac{w^2}{l^2}& \left(1\right)\end{array}$

where C.sub.T is the torsional stiffness of the torsion bar 7 and .sub.w is the roll angle of the car body 1. It is assumed that the car body 1 is torsionally stiff, so that the roll angle .sub.w is the same on both bogies 2, 3. By modifying the torsional stiffness Cr, different roll moments can be achieved on the leading and trailing bogie. Due to a higher roll 6 stiffness on the rear anti-roll stabilizer 5 than on the front anti-roll stabilizer 4, the roll moment MW, x, see FIG. 1, is supported more strongly on the trailing bogie 3. Wheel unloading is redistributed from the leading bogie to the trailing bogie 3, while the total unloading of all the windward-side wheels of the bogies 2, 3 remains the same. The stiffness of the anti-roll stabilizers 4, 5 is adjusted so that the wheel unloading on the leading and trailing bogie is the same and both bogies 2, 3 are therefore used optimally to increase the side-wind stability of the car body 1.

[0033] In order not to change the tilt coefficient of the car body 1, the roll stiffness of the anti-roll stabilizers 4, 5 is modified so that the overall roll stiffness C.sub.ges of the car body 1 remains constant. The following must therefore apply:

[00002]$\begin{array}{cc}{c}_{\mathrm{ges}}=\frac{4c^{+}+2c^{*}}{2c^{+}{c}^{*}}=\frac{2c_1^{+}+c_1^{*}}{2c_1^{+}{c}_1^{*}}+\frac{2c_2^{+}+c_2^{*}}{2c_2^{+}{c}_2^{*}}=\mathrm{const}.& \left(2\right)\end{array}$$\mathrm{with}$$\begin{array}{cc}{c}^{+}=c_{T,\mathrm{Prim}}\frac{w_{\mathrm{prim}}^2}{l_{\mathrm{prim}}^2}& \left(3\right)\end{array}$$\begin{array}{cc}{c}^{*}=C_{T,\sec }\frac{w_{\sec }^2}{l_{\sec }^2}& \left(3\right)\end{array}$

[0034] Starting from equal roll stiffnesses of the anti-roll stabilizers 4, 5, the roll stiffness of the anti-roll stabilizer of the leading bogie 2, for example, is reduced in order to increase the side-wind stability of the car body 1. As per equation 2 above, the roll stiffness of the trailing bogie 3 can be increased so that the tilt coefficient remains unchanged.

[0035] In one embodiment, a required increase or decrease in torsional stiffness for one of the torsion bars 7 can be achieved by increasing or decreasing the diameter of the relevant torsion bar 7.

[0036] An alternative option for increasing or decreasing the roll stiffness of the anti-roll stabilizers 4, 5 is to have a shorter or longer lever length 1 for the levers 9. This is explained with reference to FIG. 7.

[0037] Shortening or lengthening the lever length 1 is an effective method of modifying the roll stiffness of the antiroll stabilizers 4 and 5, as the lever length 1 is a quadratic function of the roll stiffness. In addition, when combined with the lifting of the car body 1, an additional positive effect arises:

[0038] The roll stiffnesses according to equations 2 and 3 assume small deflections of the anti-roll stabilizers 4, 5 about their neutral positions. However, in the event of strong side-wind gusts, the car body 1 is lifted by the uplift force FW, z, cf. FIG. 1, resulting in larger deflections of the secondary anti-roll stabilizers 4 and 5 of the bogies 2 and 3.

[0039] In the case of a car body 1 lifted by height h, a supporting force Fw acts on the torsion bar 7 over the lever length l.sub.eff with

[00003]$\begin{array}{cc}{l}_{\mathrm{eff}}=\sqrt{l^2-h^2}.& \left(4\right)\end{array}$

[0040] This increases the roll stiffness according to equations 2 and 3. With the same lifting on the leading and trailing bogie 2, 3 and different lever lengths l (longer lever on the leading bogie, shorter lever on the trailing bogie), the roll stiffness on the trailing bogie 3 in the lifted state of the car body 1 increases more strongly than at the front. This supports the effect to be achieved, namely the redistribution of the wheel unloading on the leading bogie and on the trailing bogie 3 under side-wind conditions. As a result, the difference in the roll stiffnesses of the anti-roll stabilizers 4, 5 in the non-lifted state of the car body 1 is less than with the previously described modification of the roll stiffness via the diameter of the torsion bars 7.