EP0387742B1 - Guided extremity vehicle of a railway train with steering axles - Google Patents

Description

et $$\text{d² = n (n+2L).}$$

The present invention relates to a guided vehicle at the end of a railway train set, with steerable axles, of the type constituted by a body carried by two main axles each provided with two wheels and comprising, at each main axle, a cross member which pivots around '' an axis relative to the body and which carries the main axle and a bar articulated around a point of the body arranged on the roll axis of the vehicle and in contact at another point with the cross member of which it controls l angle of rotation, and comprising at its free end an additional axle for guiding the main axle disposed outside, the bar being fixed on the additional guide axle perpendicularly to the middle of the latter, and in which the half -wheelbase (L) of the vehicle, the distance (n) between the center of rotation of a main axle relative to the body and the center of rotation of the corresponding bar relative to the body, length of bar (d) and distance (b) between the center of rotation of the main axle with respect to the body of the point of articulation of the bar and the cross are linked by the relationships $$\text{b = n +}\frac{\text{nL}}{\text{n + d}}$$

and $$\text{d² = n (n + 2L).}$$

It applies more particularly to the main main axles of a train (front axle of the vehicle at the head of the train, and rear axle of a vehicle at the tail of the train) and makes it possible to maintain the radiality of each axle in a curve.

A guided vehicle of this kind was the subject of document FR-A-2584040.

In an end vehicle according to this document, the points of articulation of the bar of the additional axle with respect to the body and of articulation of this bar with respect to the axle are placed above the suspension of the main axle, and are therefore subject to transverse displacements which can occur between the body and the main axle, in particular under the effect of inequalities of the track, due to their connection via this suspension. During transverse deflections between the body and the main axle, the bar of the additional axle shifts relative to the axis of the track by a certain distance and no longer remains tangent to this axis of the track, which causes a rotation of the main axle by a certain angle (yaw movement with respect to this axis), which in turn generates a return of the body in the opposite direction. Under certain conditions, the dynamic instability thus created can increase and cause unacceptable body sway oscillations.

The object of the present invention is, while retaining the orientation system of the main axle using an additional axle, to make the orientation of this main axle insensitive to the transverse deflections between the body and the axle main, thus avoiding any risk of transverse instability of the body and ensuring good comfort for vehicle passengers.

The vehicle according to the invention is characterized in that the articulation of the bar of the additional axle to the body is effected by means of a horizontal rod articulated between its ends on a vertical rod connecting the middle of the main axle in the middle of the upper part of the body suspension on the main axle.

It is described below, by way of examples and with reference to the schematic figures of the appended drawing, orientation devices of the main front axle of a vehicle at the head of a train of the known type and according to the invention.

In these figures, the angles and the transverse movement between the body and the axle have been exaggerated for greater clarity, these angles being in fact of the order of a few degrees and the movement at most of a few centimeters.

Figure 1 shows in plan the known device.

Figure 2 shows its arrangement in relation to the suspension of the main axle.

Figure 3 shows the angle that the front main axle takes with respect to the perpendicular to the center line of the track and the angle between the axis of the body and the alignment of the track, during a transverse movement of the body with respect to the main axle on a portion of straight track.

FIG. 4 represents the orientation device of the invention.

In FIG. 1, the rail vehicle follows the curved track 1 with an axis 2. Its front main axle 3 with midpoint at 4 and cross member 5 is preceded by an additional axle 11 with midpoint 12 which it drives by through the bar 9 articulated at 8 on the end of the cross-member 5 of the axle 3.

The wheels of the additional axle may have a smaller diameter than those of the main axle 3.

• demi-empattement de la voiture (ou demi-distance entre les axes de rotation des traverses de ses deux essieux principaux) : L
• longueur de la barre : d
• distance du centre de rotation 4 de l'essieu principal par rapport à la caisse au centre de rotation 10 de la barre par rapport à cette caisse : n
• distance du centre de rotation 4 de l'essieu principal par rapport à la caisse à l'articulation 8 entre l'essieu principal et la barre : b

   les relations : $$\text{b = n +}\frac{\text{n.L}}{\text{n+d}}$$

et $$\text{d² = n (n+2L)}$$

cette dernière relation traduisant l'aplomb de l'extrémité 12 de la barre avec l'axe longitudinal de la voie.As has been demonstrated in the document FR-A-2584040, the main front axle 3 and the additional axle 11 remain substantially oriented along the radius of curvature of the track, (at a very small angle ε near) and the bar coupling 9 very substantially perpendicular to this radius of curvature, provided that it exists between the lengths

• half-wheelbase of the car (or half-distance between the axes of rotation of the cross members of its two main axles): L
• bar length: d
• distance from the center of rotation 4 of the main axle relative to the body to the center of rotation 10 of the bar relative to this body: n
• distance from the center of rotation 4 of the main axle with respect to the body at the joint 8 between the main axle and the bar: b

the relationships : $$\text{b = n +}\frac{\text{nL}}{\text{n + d}}$$

and $$\text{d² = n (n + 2L)}$$

this latter relationship reflecting the balance of the end 12 of the bar with the longitudinal axis of the track.

The guiding device of the main axles thus defined is however sensitive to the relative transverse movements which appear between the body of the vehicle and its axles in a straight line, due to the presence of a suspension between these two elements, in particular as a result of unevenness of the track in height or in spacing of the rails. This sensitivity can be reflected in particular for a main axle at the head of the train by a dynamic instability between the rotation of the main axle and the transverse movement between the body and the main axle.

FIG. 2 represents the assembly of a front main axle and the associated additional axle, the suspension between the front main axle and the body being represented by the springs 14 and 15 (this suspension being naturally generally more complex).

The bar 9 which ensures the orientation of the main axle 3 is connected transversely on one side to the body by the articulation 10 and on the other side to the track via the additional axle 11.

.FIG. 3 represents the clearance which appears between the body and the main front axle of the vehicle and its influence on the orientation of the axles. The center of the body deviating by a distance t from the middle of the front main axle, the point of rotation 10 of the bar with respect to the body and the point 8 of articulation of this bar with respect to the axle 3 are placed above the suspension of this main axle and participate in this travel. The main front axle and the additional axle then deviate from the perpendicular to the axis of the track with very little different angles α # α '# $\frac{\text{t}}{\text{d + n}}$

.

This rotation of the main axles has the effect of bringing the axis of the body towards the axis of the track, but the body then exceeds its position of equilibrium in the opposite direction, generating oscillations which are liable to amplify in certain conditions. These oscillations, detrimental to the comfort of vehicle passengers, are unacceptable.

Figure 4 shows the device of the invention. The articulation point of the bar 9 relative to the body is no longer directly on the body, but is located at 17 on a rod essentially horizontal intermediate 16, the opposite end 10 of which is articulated on the body at the end of a short vertical segment. This rod is itself articulated at 18 in its central zone to the central part of a vertical rod 19 whose ends 4 and 20 are linked respectively to the lower and upper planes of the suspension of the main axle in the middle 4 of l main axle and at 20 in the middle of the cross member 21 of the main axle connecting the upper ends of the suspensions 14 and 15.

• le point de rotation 10 de la tringle intermédiaire 16 par rapport à la caisse se déplace lui aussi de la distance t par rapport à l'essieu principal.
• en admettant que le point d'articulation 18 de la tringle intermédiaire 16 autour de la tringle verticale 19 soit au milieu de cette tringle intermédiaire, ce point d'articulation se déplace de t/2 par rapport à l'essieu (et plus généralement de t/n si sa distance au point d'articulation 17 est la fraction 1/n de la longueur ramenée à un plan horizontal de cette tringle horizontale)
• le point 17 de rotation de la barre 9 par rapport à la tringle intermédiaire 16 ne se déplace pas par rapport à l'essieu principal 3.

Therefore, during a transverse movement t of the body relative to the main front axle of the vehicle, it is observed that

• the point of rotation 10 of the intermediate rod 16 relative to the body also moves by the distance t relative to the main axle.
• assuming that the articulation point 18 of the intermediate rod 16 around the vertical rod 19 is in the middle of this intermediate rod, this articulation point moves by t / 2 relative to the axle (and more generally by t / n if its distance to the articulation point 17 is the fraction 1 / n of the length reduced to a horizontal plane of this horizontal rod)
• the point 17 of rotation of the bar 9 relative to the intermediate rod 16 does not move relative to the main axle 3.

Therefore, neither the point of rotation 4 of the front main axle relative to the body, nor the fictitious point of rotation 17 of the bar relative to the body, nor the point of articulation 8 of the bar relative to the front main axle no longer undergoes transverse movements between body and main axle, and the orientation of the front main axle has become insensitive to these transverse movements. The body no longer undergoes oscillations caused by the angular corrections of the axles resulting from such displacements.

Claims (1)

1. Guided extremity vehicle of a railway train with steering axles of the type comprising a body carried by two main axles each carrying two wheels and comprising at each main axle a crossbeam (5) which pivots about an axis relative to the body and which carries the main axle (3) and a bar (9) pivoted about a point (10) on the body disposed on the roll axis of the vehicle and in contact at another point (8) with the crossbeam (5) to control its angle of rotation and comprising at its free end an externally disposed supplementary axle (11) for guiding the main axle (3), the bar (9) being fixed to the supplementary guide axle perpendicularly at the centre thereof, and in which the half-wheelbase (L) of the vehicle, the distance (n) between the centre of rotation (4) of the main axle relative to the body and the centre of rotation of the respective bar (17) relative to the body, the length (d) of the bar and the distance (b) between the centre of rotation of the main axle relative to the body and the point of articulation of the bar and the crossbeam (5) are related by the equations $$\text{b = n +}\frac{\text{nL}}{\text{n+d}}$$

   

   and $$\text{d² = n (n+2L)}$$

   

   characterised in that the articulation of the bar (9) to the body is effected by means of a horizontal link (16) articulated between its ends (10, 17) to a vertical link (19) joining the middle (4) of the main axle to the middle (20) of the upper part of the suspension (14, 15) of the body to the axle.

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