Tilting mechanism

Details Tilting mechanism Tilting mechanism

1998-10-08

2001-06-12

Morano, S. Joseph (Department: 3617)

Railway rolling stock

Trucks

Bogie

C105S199100, C280S124103, C280S005509

Reexamination Certificate

active

06244190

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a tilting mechanism for enabling curved track-dependent tilting of the superstructure of a rail vehicle, and, more particularly, to a coupling means movably connecting the superstructure with a bogie in such a way that the superstructure can be brought from an upright initial position into a tilted position relative to the bogie.
BACKGROUND ART
Tilting mechanisms are known in the prior art. They are used in “tilting trains”. These are specially designed passenger trains, their design enabling their superstructure to be turned or “tilted” around its longitudinal axis relative to a bogie. This tilting process aims at compensating the horizontal acceleration acting upon the passengers in curves. Despite a considerable improvement of cruising comfort for the passengers, the curved tracks can be traveled much faster than allowed for normal trains by the EBO (German Rules for the Construction and Operation of rail vehicles), thus enabling the passengers to reach their destination much faster over winding railroad routes.
Such tilting mechanisms are subdivided into active and passive systems. Passive systems enable a tilting of the superstructure only as a result of centrifugal forces acting upon the superstructure. The tilting angle of such systems is, however, very limited, with maximum inclination angles of 1.2 to 3.5 degrees, depending on the design. Active systems make use of an adjusting means by which the tilting between the superstructure and the bogie can be controlled via a control loop, depending on the track curve and/or the velocity. These systems are generally suitable for a maximum inclination angle of approximately 8 degrees. This invention refers to such an active tilting mechanism.
In the known systems, the adjusting means either consists of a hydraulic servo cylinder or an electromechanical linear drive. The electromechanical linear drive, for example, is designed as a combination of an electromotor and a planet roller spindle. The adjusting means is located between the superstructure and the bogie.
It is known from the tilting trains in operation that an actuator force ranging from 8 to 10 tons is installed at each of the two bogies. Values this high are needed if the superstructure is to be held in its maximum excursion position of 8 degrees, since the center of gravity of the superstructure, in the case of large inclination angles, acts via a relatively large lever arm in the sense of a restoring torque. Forces this high are necessary to enable the superstructure to automatically return to its untilted initial position in case of a default of the tilting mechanism.
The design of the linear drive depends on the largest forces becoming active at a maximum angle of inclination. Furthermore, a relation between actuator force and the required torque at the motor exists for the known electromechanical actuators. In case of such a drive, it means that, for producing the necessary force, a current in the servo motor is necessary, its strength being also proportional to the angle of inclination. Since it is known that the stray power in a motor increases with the square of the engine current, this results in a considerably high stray power if the superstructure inclination is moving at high excursion angles.
This leads to the fact that the electromotor as well as the power electronics supplying it with electricity have to be designed for high levels of permanent power, naturally influencing the cost of acquisition of the mechanism. Furthermore, the dimensions of the drive have a major influence on the required space for installation. For larger drive motors, this installation space has to be sufficiently large.
Hence, it would be useful to create an actuator for the track curve-dependent control of a superstructure not characterized by the disadvantages described above with respect to the stray power occurring during operation at large inclination angles, and being additionally designed in a more compact and cost-efficient way.
DISCLOSURE OF THE INVENTION
With reference to the corresponding parts, portions, or surfaces of the disclosed embodiment, merely for the purpose of illustration and not by way of limitation, the present invention solves the problems found in the prior art by providing a transfer means with a mechanism with variable transmission, the transmission of the mechanism increasing with the increasing angle of inclination of the superstructure relative to the bogie when transferring the superstructure from its initial position into a tilted position.
This solution has the advantage that a larger transmission is provided in case of increasing inclination forces, thus making a considerably smaller dimensioned drive sufficient to cope with larger forces. Consequently, the transmission is lower at smaller angles of inclination and increases with increasing angles of inclination. A smaller transmission at smaller angles of inclination is desirable, thus reducing the gear losses and enabling small actuator forces to safely bring the superstructure into the untilted initial position. Since a smaller drive with respect to the required permanent power is sufficient at comparable forces based on the angle of inclination, this has an influence on the drive itself as well as on the power electronics and the wiring, thus enabling a more inexpensive design of the tilting mechanism. A smaller drive also requires less installation space.
In an advantageous development of the invention, the mechanism could include a crankshaft, consisting of a crank pin being displaced radially to the crankshaft and a drawbar and/or side rod pivotably connected to the crank pin. With such a gear, a considerable transmission ratio can be easily realized for variable gear ratios. In particular, in case of an almost aligned crank mechanism, almost any large transmission can be realized.
The advantage resulting from a high gear transmission at large angles of inclination has a major effect on electromotor drives withstanding large actuator forces. In the case of electromotor drives, the stray power is mainly influenced by the transmission of engine torques and not by the adjusting velocity, as is the case with hydraulic linear actuators. On the other hand, electromotors are also considered to have an advantage over hydraulic or pneumatic drive units in that they need not be maintained so often, are easily available, have lower life cycle cost, are more easily mountable and consume less energy, thus being very environment-friendly.
Moreover, a gear between the mechanism and the drive motor can be of the reduction type. The result is that even small electromotors can create the necessary active forces and/or transverse forces to bring the superstructure from its initial position to its tilted position.
It can be advantageous to connect an electromotor with the reduction gear and/or crank mechanism by means of an universal joint. In doing so, the electromotor can be installed in a more advantageous position, thus enabling a more compact design of the tilting mechanism.
As an alternative, the motor could also be connected to the reduction gear and/or to the crank mechanism by means of a belt drive or a chain drive. Also, in this case, the tilting mechanism can be designed in a compact way by installing the motor in a suitable space distant from the reducing gear.
In a preferred embodiment, a line through the center of the crankshaft and the crank pin and a line through the center of the crank pin and the position of the bearing of the drawbar and/or side rod located distant to the crank pin can basically form a right angle in the initial position of the superstructure. This results in a particularly favorable force progression when initially bringing the superstructure from its initial position into a tilted position.
Extremely large inclination forces can be obtained if the crank mechanism is almost straight at a maximum inclination angle.


REFERENCES:
patent: 3717104 (1973-02-01), Law et al.
patent: 4503504 (1985-03-01), Suzumura et al.
p

Affiliated with

Also associated with

Rating

Tilting mechanism does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Tilting mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tilting mechanism will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2501191