WO2023011673A1

WO2023011673A1 - Two-axle rail vehicle bogie

Info

Publication number: WO2023011673A1
Application number: PCT/CZ2021/000037
Authority: WO
Inventors: František Sedláček; Vladislav Laš; Radek KOTTNER; Jan Krystek; Martin ZAJÍČEK
Original assignee: University of West Bohemia
Current assignee: University of West Bohemia
Priority date: 2021-08-02
Filing date: 2021-08-02
Publication date: 2023-02-09
Anticipated expiration: 2024-02-02

Abstract

A two-axle rail vehicle bogie comprising a bogie frame (1) consists of a pair of side beams (11) connected with at least one central transom (2). Primary suspension (5) is provided between the side beam (11) and a bearing housing (41) of each of the axles (4). Both bearing housings (41) belonging to one side beam (11) are mutually connected with a leaf spring (3) which rests against the bottom side of the bogie frame (1). The leaf spring (3) is attached to the bearing housings (41) by a pin joint.

Description

Two-axle rail vehicle bogie

Technical Field

The invention is a two-axle rail vehicle bogie which comprises a bogie frame consisting of a pair of side beams connected with at least one central transom, where primary suspension is provided between the side beam and the bearing housing of each axle.

Background Art

In order to reduce the effect of primary masses on the suspension and to reduce the effects of the running gear on the railway superstructure, structures are designed with regard to reducing weight. From the weight perspective, efforts are focused on creating structures with as low weight as possible, particularly with unsprung masses which have a considerable impact on the dynamic behaviour of the bogie and related running stability. In one alternative, bogie frames are designed and built from welded sections and castings of minimized weight, in others parts from composites are used. One bogie constructed in this fashion is disclosed in publication no. US6305297, comprising an elastic leaf in the shape of a flat loop which may be built from a composite material or a metal. The direct connection between the elastic element which acts as primary suspension and the bearing housing makes the bogie with this configuration suitable for low-weight rail vehicles.

Publication no. US6338300B1 discloses elastic mounting of axles in axle boxes which are connected to the bogie frame by an elastic leaf made of a composite material which operates as primary suspension. Between the elastic leaf and the bearing housing, rubber-metal primary suspension is incorporated. The bearing housings are connected to the bogie frame by longitudinal arms in the form of draw rods. A combination of a connection between bearing housings and the bogie frame with longitudinal arms and a connection of bearing housings with a leaf spring resting on top of the bearing housings either directly or through primary suspension is disclosed in publication no. US2014/0137765A1. In this case, the longitudinal arms in the form of pivoting arms increase the unsprung mass, as in the previous solution.

Another equally closely monitored parameter of bogies is their functioning in terms of wheelset guidance. The purpose of wheelset guidance is to transfer forces between the axle box in which the wheelset is supported and the bogie frame. There are a great number of different design concepts. The reason is the conflicting requirements on its functional properties, which includes a requirement for a low frequency of the sinusoidal movement of the wheelset on a straight track. This is achieved with a design which keeps both wheelset parallel. This requirement is met, for instance, by a hornplate which guides the wheelset. One of the best known representatives is the Y25 bogie. One disadvantage is that bogies of this type possess very heavy unsprung masses and therefore are only suitable for low speeds and, in addition, their high torsional stiffness results in severe wear on the wheel flange and rail. Modernized Y25 DRRS bogies have mitigated this problem to some extent. A more notably optimized variant is disclosed in publication no. EP1057707A1 where a bogie frame with a greater torsional compliance has a single progressive spring on each side of the bearing housing. Despite these alterations which enable the maximum speed to be increased, this bogie is not well suited for high speeds and its structure is still relatively heavy. Additional requirements include minimization of wear on the tread profile of the wheelset, which is met by designs which enable radial steering during curve negotiation. To fulfil this requirement, wheelset guidance with inclined rubber blocks of vertical suspension is used where the blocks are interposed between the bearing housing and the bogie frame in such manner that reactive forces shift the wheelset to the radial orientation as it enters the curve. These bogies include, for instance, BVT 5047 or a bogie of a similar design disclosed in publication no. US10059351 B2. One disadvantage of this design, however, is the high stiffness of the primary suspension which only consists of rubber blocks, and therefore adequate anti-derailment stability is not provided. This problem is addressed at the cost of reduced stiffness of the bogie frame alone. For this reason, this bogie is only used for low-speed applications. In passenger car bogies and applications with higher speeds, a fit with no clearance is used. These solutions include wheelset guidance with the use of friction dampers and wheelset guidance using pivoting arms or draw rods, which is often used in recent years, as disclosed in publication no. US4658734A. These variants provide a fit with no clearance but the need for rubber bushings on connecting journals is at the cost of greater compliance of the bogie in the transverse direction which is undesirable from the viewpoint of ride dynamics, comfort and stability.

Disclosure of Invention

The invention is a two-axle rail vehicle bogie which comprises a bogie frame consisting of a pair of side beams connected with at least one central transom. Primary suspension is interposed between the side beam and a bearing housing of each of the axles. In an example embodiment, the primary suspension comprises a combination of longitudinally-positioned leaf springs and rubber-metal elastic segments placed between bearing housings and side beams of the bogie frame. The initial portion of the primary suspension characteristic is provided by continuous leaf springs which are pre-stressed and mounted within individual side beams of the bogie frame. When the car exerts increased forces on the suspension, for instance when riding across large irregularities, the clearance between central guide pins located at the ends of bogie frame side beams and the seats of rubber-metal springs is closed and the stiffness of these elements is superposed onto the suspension characteristic. Both bearing housings belonging to a single side beam are connected with a leaf spring which rests against the bottom of the bogie frame and is attached to the bearing housings with a pin joint. The leaf springs are attached to the central portion of the bogie frame, directly below the secondary suspension of the bogie. This configuration provides effective force transmission within the bogie frame between the wheelset and the car. As a result, the loading on the side beams in the transverse direction is reduced which allows for using geometries with a greater compliance in this direction. The bogie frame itself may therefore contribute to primary suspension. The direct connection between the leaf spring and bearing housings precludes the use of longitudinal arms or draw rods which would otherwise reduce the unsprung mass.

Making the leaf spring from a composite material reduces the weight of the bogie and the amount of space required for installing the leaf spring. In this case, the composite material is a combination of carbon or glass reinforcement in the form of long fibres and epoxy or polyester resin. When made from a composite material, an integral leaf element of the leaf spring can have a variable cross section which provides a vertical stiffness characteristic close to that of a constantstiffness beam, and therefore produces a progressive characteristic of the primary suspension. The widened ends provide high transverse stiffness which helps the wheelset guidance in the transverse direction. As a result, there is potential for further reduction of the bogie weight and an opportunity for making the entire frame from a composite material.

Description of drawings

The drawing shows the bogie frame in a broken-out section view with indicated axle supports.

Best Mode for Carrying out the Invention

A two-axle rail vehicle bogie comprises a bogie frame consisting of a pair of side beams 11 connected with at least one central transom 2. Between side beam 11 and bearing housing 21 of each axle 4, primary suspension 5 in the form of rubber-metal elements is interposed. Both bearing housings 21 belonging to one side beam 11 are mutually connected with leaf spring 3 which rests against the bottom side of the side beam 11 of bogie frame 1.. For this purpose, the side beam 11 is provided with a pair of seats. Bearing housings 41 are built around the wheelset 4 axis. Ends of the leaf spring 3 are attached to bearing housings 41 with pin joints. Between each bearing housing 41 and the frame 1, damper 6 is incorporated. The leaf spring 3 may be made from steel or, in order to reduce weight, from a composite material. Equally, the bogie frame may be fabricated as a weldment or from a composite material.

The vertical movement of axles 4 is restricted by primary suspension 5 and its dampers 6 arranged in parallel. One strong aspect of the design configuration is the leaf spring 3 which provides a kinematic link between two bearing housings 41, which affects their joint vertical movement and provides longitudinal guidance of the wheelset.

Claims

1. A two-axle rail vehicle bogie comprising a bogie frame (1) consisting of a pair of side beams (11) connected with at least one central transom (2), where between the side beam (11) and bearing housing (21) of each axle (4) there is interposed primary suspension (22), characterized in that both bearing housings (21) belonging to one side beam (11) are connected with a leaf spring (3) which rests against the bottom of the bogie frame (1), where the leaf spring (3) is attached to the bearing housings (21) by a pin joint.

2. The two-axle rail vehicle bogie according to claim 1 or 2, characterized in that the leaf spring (3) is made from a composite material.

3. The two-axle rail vehicle bogie according to claim 1 or 2, characterized in that the bogie frame (1) is made from a composite material.

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