Secondary suspension with level control for a rail vehicle

Abstract

The invention relates to a secondary suspension with level control for a rail vehicle, said secondary suspension being designed to be arranged between a railcar body (2) of a rail vehicle and a bogie frame (3), comprising at least one air spring bellows (1) and a level control valve (4) which sets the air quantity in the air spring bellows (1) on the basis of the distance of the bogie frame (3) to the railcar body (2) such that the distance assumes a specific value. A linkage (8) acts on a mechanical actuation of the level control valve (4) on the basis of the distance between the railcar body (2) and the bogie frame (3), wherein a compressed air actuator (7) is provided to which the current air pressure in the air spring bellows (1) is applied and which produces, on the basis of the air pressure in the air spring bellows (1), a change in the transmission characteristic between the distance of the bogie frame (3) to the railcar body (2) and an actuation of the level control valve (4).

Description

[0001] 202316836 Description Secondary suspension with level control for a rail vehicle Technical field The invention relates to a secondary suspension with level control for a rail vehicle. State of the art New passenger rail vehicles are usually equipped with an air suspension, which typically comprises two compressed air-filled air bellows per chassis, which are arranged between the car body and the chassis, or more precisely, the chassis frame. Such air suspensions are advantageous because they provide good vibration and noise isolation of the car body and thus the passenger compartment, which is essential for increased passenger comfort. A chassis, in particular a bogie, also has a so-called primary suspension.which can be designed as a steel spring and which is arranged between the wheelset and the bogie frame. This primary suspension reduces the unsprung mass of the rail vehicle to a minimum. So that only the wheelset and axle bearings, as well as parts of the braking system and the drive train, are considered unsprung masses. This reduction is significant, as low unsprung masses are relevant both for passenger comfort and for reducing rail wear. In local transport vehicles, especially subways, the 202316836 air suspension is usually equipped with a level control system, the purpose of which is to keep the passenger compartment floor at the same level above the top of the rail, regardless of the load. This is intended to minimize the so-called vertical platform gap, i.e. the level difference between the platform and the top of the floor of the rail vehicle.This is very advantageous for rapid passenger transfer without the risk of tripping. This level control system determines the vertical distance between the chassis frame and the car body and, depending on this distance, increases or decreases the air volume in the air bellows, so that the car body lowers or raises, respectively, and a target value for the vertical clearance is established. However, conventional level control systems cannot determine and therefore compensate for other factors influencing the vertical platform gap, such as wheel wear, rail wear, vertical track misalignments, or car body deflection. Likewise, the compression of the primary spring due to the current vehicle mass cannot be compensated, so precise control of the vertical platform gap is not possible. There are approaches to solving this problem.which provide a direct measurement of the vertical platform gap and minimize this gap by changing the air volume in the air spring bellows. However, suitable sensors, computing devices, and actuators must be used for this, which must also be designed with the safety required for rail vehicle suspensions, which significantly increases the construction effort and the price of this device. However, even taking into account the deflection of the primary suspension, typically up to 30 mm, is a significant advantage, since the influence of the primary suspension on the vertical platform gap 202316836 is generally the greatest compared to other non-adjustable influencing factors. Description of the invention The invention is therefore based on the object of specifying a secondary suspension with level control for a rail vehicle, which is capable of compensating the deflection of the primary suspension,so that the height of the car body above the track level can be kept constant. This object is achieved by a secondary suspension with level control for a rail vehicle having the features of claim 1. Advantageous embodiments are the subject of subordinate claims. According to the basic idea of ​​the invention, a secondary suspension with level control for a rail vehicle is described, which is designed to be arranged between a car body of a rail vehicle and a bogie frame, which comprises at least one air spring bellows and a level control valve, wherein the level control valve adjusts the air volume in the air spring bellows depending on the distance between the bogie frame and the car body so that this distance assumes a specific value, wherein a linkage acts on a mechanical actuation of the level control valve depending on the distance between the car body and the bogie frame,and wherein a compressed air actuator is provided, which is acted upon by the current air pressure in the air bellows, and which, depending on the air pressure in the air bellows, causes a change in a 202316836 transmission characteristic between the distance of the bogie frame to the car body and a control of the level control valve. This provides the advantage of being able to compensate for the compression of the primary suspension by adjusting the air quantity in the air bellows, depending on the pressure prevailing in an air bellows, which is determined by the current vehicle mass, and the resulting current compression of the primary spring. According to the invention, a secondary suspension with level control is constructed such that, generally, two air bellows are arranged per bogie between the car body and a bogie frame (except in special vehicle concepts).which are pressurized with compressed air via a level control valve so that the vertical distance between the car body and the bogie frame assumes a specific value. This distance is dimensioned to ensure the smallest possible vertical platform gap. According to the invention, the deflection of the primary suspension is taken into account and compensated for by feeding the air pressure prevailing in the air bellow(s) to a compressed air actuator, which mechanically changes the transmission characteristic between the distance of the bogie frame to the car body and the activation of the level control valve. In this way, with increasing pressure, typically due to the vehicle being loaded with passengers, the air volume in the air bellows can be increased even further.so that the distance between the bogie frame and the car body is increased by the compression travel of the primary suspension and the vertical platform gap is further minimized. Based on the known spring characteristic of the primary suspension, the components of the secondary suspension with level control according to the invention can be dimensioned such that the compression of the primary suspension is compensated for any permissible load. It is advantageous to change the transmission characteristic between the distance between the bogie frame and the car body and the control of the level control valve by arranging the pneumatic actuator in such a way thatthat, depending on the air pressure in the air bellows, a change in length proportional to the deflection of the primary spring is effected in a rod of the linkage. As a result, with increasing air pressure in the air bellows, an additional control of the level control valve is carried out and the air quantity in the air bellows is increased proportionally to the deflection of the primary spring. A further preferred embodiment of the invention provides for the pivot point of the linkage on the bogie frame to be moved depending on the pressure in the air bellows. The pneumatic actuator is to be arranged stationary on the bogie frame and the linkage is to be connected to the movable part of the pneumatic actuator. The pressure in the air bellows causes a proportional change in the position of the pivot point. In a further development of the invention, it is advantageousto effect the change in the transmission characteristic between the distance of the bogie frame to the car body and the actuation of the level control valve by moving the level control valve itself by the pneumatic actuator. A linear displacement or a pivoting movement of the level control valve can be provided. This is particularly advantageous if no changes are to be made to the chassis (bogie) or if there is no installation space for a pneumatic actuator and the associated cable routing. Furthermore, it is advantageous to arrange the pneumatic actuator in such a way that the kinematics of the linkage are changed depending on the air pressure in the air bellows, in particular by inserting a rocker arm, via which the pneumatic actuator acts on the linkage. This is particularly advantageousBecause by varying the position of the pivot point along the rocker arm, the compensation effect can be precisely adjusted by the pneumatic actuator. The pneumatic actuator is preferably equipped with a return spring so that if the pressure in the air spring bellows drops, the compensation effect is withdrawn. The present invention can compensate for the deflection of a primary suspension without having to use electrical or electronic components; in particular, it does not require any electronic sensors or software. Brief description of the drawings. Examples include: 202316836 Fig. 1 Secondary suspension with level control, length change in the rod. Fig. 2 Secondary suspension with level control, displacement of the rod's pivot point on the chassis frame. Fig. 3 Secondary suspension with level control, movable level control valve. Fig. 4 Secondary suspension with level control,Tilting device. Fig. 5 shows an example and schematically a mass-pressure characteristic curve embodiment of the invention. Fig. 1 shows an example and schematically a secondary suspension with level control with a pneumatically controlled length change in the linkage to a level control valve. A secondary suspension is shown in a highly abstract manner, which comprises an air bellows 1 arranged between a car body 2 of a rail vehicle and a bogie frame 3. The air bellows 1 is fed from the compressed air supply 5, wherein a level control valve 4 is provided, which specifies the amount of air fed to the air bellows 1 via the compressed air line 6. The level control valve 4 can also release excess air from the air bellows 1. A linkage 8 mechanically connects the bogie frame 3 to a control input of the level control valve 4, so that the level control valve 4, when approaching,i.e., lowering the car body 2 onto the bogie frame 3 increases the air volume in the air bellows 1, so that the 202316836 air bellows 1 subsequently raises the car body 2 and the car body 2 returns to its target height above the bogie frame 3. If the car body 2 moves vertically away from the bogie frame 3 and exceeds the target height, for example due to the removal of the load, the level control valve 4 vents the air bellows 1 until the car body 2 returns to its target height above the bogie frame 3. In the illustrated embodiment, this basic level control function is expanded to include compensation for the compression of the primary suspension. The primary suspension itself is not shown in Fig. 1, as it is not required to compensate for its current compression travel.Rather, it is derived from the pressure in the air bellows 1. The rod assembly 8 intended for producing a conventional level control device is extended by a length-adjustable rod section 10, which is inserted into the rod assembly 8. Depending on the length of this rod section 10, the transmission characteristic between the distance of the bogie frame 3 to the car body 2 and the actuation of the level control valve 4 is changed, so that with increasing pressure in the air bellows 1, a further increase in the air quantity in the air bellows 1 is effected, compensating for the compression of the primary suspension. In the illustrated embodiment, this change in length is achieved by means of a compressed air actuator 7, which is supplied with the air bellows pressure via a line 12. The compressed air actuator 7 is pivotally connected to the bogie frame 3 via a pivot point 9 and has a return spring.which, when the pressure in the air bellows 1 drops, reduces the length of the variable-length rod section 10 again, thus dissipating the increase in the air volume in the air bellows 1 introduced to compensate for the compression of the primary suspension. The embodiment of the invention shown in Fig. 1 offers the advantage that only minor changes need to be made to the bogie frame 3.Since the pivot point 9 can be directly taken over by a conventional secondary suspension with level control, and at most, the length-adjustable rod section 10 with the pneumatic actuator 7 needs to be inserted into the rod 8, and the line 12 for the air bellows pressure needs to be provided. No modifications are required on the car body side. Fig. 2 shows, as an example and schematically, a secondary suspension with level control with a pneumatic actuator 7 that can be moved to compensate for the compression of the primary suspension. The secondary suspension from Fig. 1 is shown, but the pivot point 9 for the rod controlling the level control valve 4 is arranged to be movable. This displacement is effected by the pneumatic actuator 7, which itself is firmly connected to the bogie frame 3. This embodiment requires a corresponding mount for the pneumatic actuator 7 on the bogie frame 3.However, flexible lines for supplying pressure to the compressed air actuator 7 are omitted. Fig. 3 shows, by way of example and schematically, a secondary suspension with level control with a level control valve 4 that can be moved to compensate for the deflection of the primary suspension. This embodiment offers the advantage of being able to arrange all components required to compensate for the deflection of the primary suspension on the car body 2; no changes are required to the bogie frame compared to a secondary suspension without compensation for the deflection of the primary suspension. According to this embodiment, the level control valve 4 itself is arranged to be movable, with this displacement being effected by the compressed air actuator 7 attached to the car body 2.which is pressurized from the compressed air line 6 to the air bellows 1. This embodiment also offers the advantage of simple line routing to the compressed air actuator 7 due to its proximity to the level control valve 4. Since conventional level control valves 4 usually have a rotary axis as a mechanical control input for determining the amount of air supplied to the air bellows 1, a pivoting movement of the level control valve 4 can also be provided, which rotates by a certain angular amount depending on the air spring pressure by the compressed air actuator 7, thus causing a further pressure increase in the air bellows 1 that compensates for the deflection of the primary suspension. Fig. 4 shows an example and schematically a secondary suspension with level control with a tilting device provided to compensate for the deflection of the primary suspension.Similar to the embodiments presented in Figs. 1 and 2, a bogie frame-side device is shown, comprising a pneumatic actuator 7 acted upon by the air spring pressure. The pneumatic actuator 7 is acted upon by the pressure in the air bellows 1 and acts on the linkage 8 via a rocker arm 11 mounted at the articulation point 9. This embodiment offers the advantage of only having to perform rotary movements in the linkage 8 and the rocker arm 11 202316836.so that potentially problematic straight-line guides can be eliminated. Fig. 5 shows an example and schematically a mass-vertical car body position characteristic curve. It is a linearized characteristic curve of the relationship between the vehicle mass M and the vertical position of the car body z above the track level. Characteristic curve 13 corresponds to a vehicle with secondary suspension without compensation for the deflection of the primary suspension and extends from a point M1 of the vehicle's unladen mass to a point M2 of the maximum vehicle mass, whereby each mass point is given a vertical position z of the car body according to characteristic curve 13, starting from a nominal position z1 at the vehicle's unladen mass to a position z2 at the vehicle's maximum mass. A characteristic curve 14 of a secondary suspension with compensation for the deflection of the primary suspension is inserted in the diagram, which intersects characteristic curve 13 at point M1 of the vehicle's unladen mass.However, in the direction of increasing vehicle mass, it deviates from this, since with the primary spring deflection compensation, the vertical position of the car body remains unchanged. At the maximum vehicle mass M2, a difference ǻz in the vertical position of the car body results compared to a secondary suspension without deflection compensation.

[0002] 202316836 List of designations 1 Air bellows 2 Car body 3 Bogie frame 4 Level control valve 5 Compressed air supply 6 Compressed air line to the air bellows 7 Compressed air actuator 8 Rod 9 Articulation point 10 Length-adjustable rod section 11 Rocker arm 12 Line for air bellows pressure 13 Pressure characteristic curve of secondary suspension without compensation 14 Pressure characteristic curve of secondary suspension with compensation M Vehicle mass M1 Unladen vehicle mass M2 Maximum vehicle mass z Vertical position of the car body above the track level z1 Nominal position of the car body above the track level z2 Position of the car body at maximum vehicle mass ǻz Difference in car body position

Claims

202316836 Patent claims 1. Secondary suspension with level control for a rail vehicle, designed for arrangement between a car body (2) of a rail vehicle and a bogie frame (3), comprising at least one air spring bellows (1) and a level control valve (4), which, depending on a distance of the bogie frame (3) to the car body (2), adjusts the air quantity in the air spring bellows (1) so that this distance assumes a specific value, wherein a rod (8) acts on a mechanical actuation of the level control valve (4) depending on the distance between the car body (2) and the bogie frame (3), characterized in that a compressed air actuator (7) is provided, which is acted upon by the current air pressure in the air spring bellows (1),and which, depending on the air pressure in the air spring bellows (1), causes a change in a transmission characteristic between the distance of the bogie frame (3) to the car body (2) and the activation of the level control valve (4).

2. Secondary suspension with level control for a rail vehicle according to claim 1, characterized in that the change in the transmission characteristic between the distance of the bogie frame (3) to the car body (2) and the activation of the level control valve (4) causes a compensation for the deflection of a primary suspension. 202316836 3. Secondary suspension with level control for a rail vehicle according to claim 1 or 2, characterized in that the compressed air actuator (7) is arranged such that, depending on the air pressure in the air bellows (1), a change in the length of a rod of the linkage (8) is effected.

4. Secondary suspension with level control for a rail vehicle according to claim 1 or 2, characterized in that the compressed air actuator (7) is arranged such that, depending on the air pressure in the air bellows (1), a change in the position of a pivot point (9) of the linkage is effected.

5. Secondary suspension with level control for a rail vehicle according to claim 1 or 2, characterized in that the compressed air actuator (7) is arranged such that, depending on the air pressure in the air bellows (1), a change in the position of the level control valve (4) is effected. 6.Secondary suspension with level control for a rail vehicle according to claim 1 or 2, characterized in that the pneumatic actuator (7) is arranged such that the kinematics of the linkage (8) are changed depending on the air pressure in the air spring bellows (1).

7. Secondary suspension with level control for a rail vehicle according to claim 6. 202316836 characterized in that the pneumatic actuator (7) acts on a rocker arm 11 mounted at the articulation point 9 on the linkage 8.

8. Secondary suspension with level control for a rail vehicle according to one of claims 1 to 7, characterized in that the pneumatic actuator (7) is equipped with a return spring.

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