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(11) | EP 3 006 299 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A bogie with a secondary suspension having a load balance device |
| (57) A bogie (300) comprising a bogie frame (302) having two opposite longitudinal sides
(304, 306), and a secondary suspension system (308), wherein the secondary suspension
system (308) includes at least two spring assemblies (310, 312) including an air spring
(314) and equally distributed on both longitudinal sides (304, 306) of the bogie frame,
and an emergency spring device (311) operating in case of air pressure loss in the
air springs (314) and having an emergency spring (316) within each spring assembly, wherein the emergency spring device (311) comprises a load balance device (319) adapted to, during operation of the bogie and in case of air pressure loss in the air springs (314), balance the loads between emergency springs (316) on opposite longitudinal sides (304, 306) by moving these emergency springs (316) in opposite directions, and thus enable a relative rolling movement between the bogie (300) and the vehicle body (B). |
[0001] The present invention relates to a bogie for a railway vehicle, the bogie comprising a bogie frame having two opposite longitudinal sides and a secondary suspension system located on the bogie frame, wherein the secondary suspension system includes at least two spring assemblies including an air spring and equally distributed on both longitudinal sides of the bogie frame and an emergency spring device operating in case of air pressure loss in the air springs and having an emergency spring within each spring assembly.
[0002] Such a bogie is known and is shown in cross-section in Figure 1, where it supports a vehicle body B. This bogie 100 comprises a bogie frame 102 having two opposite longitudinal sides 104 and 106. The two opposite longitudinal sides are defined by two longitudinal beams of the bogie frame 102. Bogie 100 is fitted with a secondary suspension system 108 connecting vehicle body B to bogie 100. Secondary suspension system 108 is delimited by the box in dashed lines. Secondary suspension system 108 has two spring assemblies 110, 112 sitting on opposite longitudinal sides 104, 106 of bogie 100. Each spring assembly 110, 112 includes an air spring 114 and an emergency rubber suspension pack 116 located inside the air spring 114. The rubber suspension packs 116 are redundant and provide a minimum suspension of the vehicle body B on the bogie 100 in case of air pressure loss in the air springs 114. Secondary suspension system 108 is equipped with an air pipe 118 interconnecting the air springs 114 to balance the loads between the two air springs 114. The air volume is transferred by the air pipe 118 from the air spring 114 with higher vertical load to the air spring 114 with lower vertical load.
[0003] A drawback of this type of known secondary emergency suspension is a limited protection against derailing. Indeed, under emergency operation when the vehicle body B is directly supported by the rubber suspension packs 116, there is little room for any relative rolling movement between the vehicle body B and the bogie 100. Thus, the bogie 100 cannot sufficiently adapt its position when it encounters twisted rails, which results in derailing.
[0004] A second known bogie is shown in Figure 2. This bogie 200 comprises a bogie frame 202 having two opposite longitudinal sides 204 and 206. The two opposite longitudinal sides are defined by two longitudinal beams of the bogie frame 202. Bogie frame 202 also comprises two crossbeams 203, 205 extending between the longitudinal beams 204, 206. Bogie 200 is fitted with a secondary suspension system 208. Secondary suspension system 208 is delimited by the box in dashed lines. Secondary suspension system 208 has two pairs P1, P2 of air springs 214. Secondary suspension system 208 also includes two emergency springs 216. The central part of each crossbeam 203, 205 supports one of the emergency springs 216. The emergency springs 216 are redundant and provide a minimum suspension of a vehicle body on the bogie 200 in case of air pressure loss in the air springs 214.
[0005] By arranging the emergency springs 216 in the bogie's centre, in emergency suspension mode, bogie 200 and its vehicle body can perform a compensating rolling movement relative to each other when encountering twisted rails, which prevents derailing.
[0006] However, in emergency suspension mode, the weight of the vehicle body is taken up via the emergency springs 216 by the crossbeams 203, 205. This means that the crossbeams 203, 205 must have a sturdy and complex design, which makes the bogie 200 heavier and more expensive.
[0007] An object of the present invention is therefore to provide a bogie for a railway vehicle with a secondary suspension system having an emergency spring device that combines good derailing protection with great constructional simplicity.
[0008] This object is achieved with the above-defined bogie, characterised in that the emergency spring device comprises a load balance device adapted to, during operation of the bogie as a vehicle body support and in case of air pressure loss in the air springs, balance the loads between emergency springs on opposite longitudinal sides by moving these emergency springs in opposite directions, and thus enable a relative rolling movement between the bogie and the vehicle body.
[0009] Thanks to the inventive load balance device that compensates a load difference between two opposite emergency springs by moving them in opposite directions, in emergency suspension mode, the inventive bogie and its vehicle body can carry out a rolling movement relative to each other when encountering twisted rails, thus preventing derailing.
[0010] At the same time, the inventive secondary suspension system is of simple and inexpensive design since the emergency springs are integrated with the air springs into one spring assembly.
[0011] According to preferred embodiments, the inventive bogie also comprises one, several or all of the following features, taken in all technically feasible combinations:
- the bogie has two pairs of two spring assemblies, the two spring assemblies of one pair facing each other on opposite longitudinal sides of the bogie frame;
- the load balance device operates hydraulically;
- the hydraulic load balance device comprises:
- for each spring assembly, a hydraulic piston connected thereto;
- for each spring assembly, a hydraulic pressure chamber supporting the spring assembly and slidingly receiving its hydraulic piston; and
- for each pair of spring assemblies on opposite longitudinal sides, a hydraulic pressure balancing line hydraulically connecting the two hydraulic pressure chambers of the two spring assemblies;
- the two hydraulic pressure balancing lines of the two spring assembly pairs are hydraulically interconnected;
- the two hydraulic pressure balancing lines of the two spring assembly pairs are hydraulically separated;
- each hydraulic piston is integrally formed at the lower end of the emergency spring of the corresponding spring assembly;
- the hydraulic load balance device includes a hydraulic liquid reservoir;
- a failure sensor for detecting a failure of the load balance device.
[0012] The invention also pertains to a railway vehicle including at least one bogie as defined above.
[0013] Preferred embodiments of the invention will be now described in detail with reference to the appended drawings, wherein:
Figure 1 is a cross-sectional view of a railway vehicle with a bogie having a first type of known secondary suspension system;
Figure 2 is a top view of a bogie having a second type of known secondary suspension system;
Figure 3 shows a cross-section of an inventive bogie with a pair of spring assemblies interconnected by a hydraulic load balance device according to the invention;
Figure 4 is a top view of a bogie according to the invention, with a hydraulic load balance device having two hydraulically separate hydraulic pressure balancing lines; and
Figure 5 is a top view of another bogie according to the invention, with a hydraulic load balance device having two hydraulically interconnected hydraulic pressure balancing lines.
[0014] With reference to Figure 3, there is shown a railway vehicle bogie 300 according to the invention. Bogie 300 comprises a bogie frame 302. Bogie frame 302 has a first and a second longitudinal beam 304, 306, as well as a crossbeam 303 extending between the two longitudinal beams 304, 306. The longitudinal beams define two opposite longitudinal sides 304, 306 of the bogie frame 302. A secondary suspension system 308 is installed on the bogie frame 302. Secondary suspension system 308 is delimited by the box in dashed lines. Secondary suspension system 308 is interposed between bogie 300 and a vehicle body B.
[0015] Secondary suspension system 308 includes a first and a second spring assembly 310, 312 and an emergency spring device 311. Emergency spring device 311 is delimited by a chain-dotted line. The first spring assembly 310 is mounted on the first longitudinal beam 304. The second spring assembly 312 is mounted on the second longitudinal beam 306.
[0016] Each spring assembly 310, 312 comprises an air spring 314 and an emergency spring 316. Each air spring 314 is supported by its corresponding emergency spring 316. In other words, each emergency spring 316 is arranged below its corresponding air spring 314, between said air spring 314 and the corresponding longitudinal beam 304, 306. Preferably, each emergency spring 316 is a rubber spring. An upper side 317 of each air spring 314 supports the vehicle body B.
[0017] The emergency spring device 311 comprises the two emergency springs 316 and a hydraulic load balance device 319. The hydraulic load balance device 319 is delimited by the dotted line. The hydraulic load balance device 319 comprises one hydraulic piston 320 and one hydraulic pressure chamber 322 for each spring assembly 310, 312. The hydraulic load balance device 319 also comprises a hydraulic pressure balancing line 324 and a hydraulic liquid reservoir 326.
[0018] Each hydraulic piston 320 is integrally formed at the lower end of the emergency spring 316 of its corresponding spring assembly 310, 312. Each hydraulic piston 320 is slidingly received within one of the hydraulic pressure chambers 322 and can reciprocate therein. The bottom 328 of each hydraulic pressure chamber 322 is fluidly connected to one end of the hydraulic pressure balancing line 324. Accordingly, hydraulic pressure balancing line 324 hydraulically interconnects the two hydraulic pressure chambers 322. A branch-off 330 connects the hydraulic pressure balancing line 324 to the hydraulic liquid reservoir 326. The hydraulic liquid reservoir 326 may be attached to the crossbeam 303.
[0019] The two hydraulic pressure chambers 322, the hydraulic pressure balancing line 324 and the hydraulic liquid reservoir 326 are all filled with a hydraulic liquid L, such as oil. Together, they form a closed hydraulic liquid containing vessel.
[0020] The operation of the secondary suspension system 308 is as follows:
During normal operation, the air springs 314 are pressurised and provide a suspension for the vehicle body B in the usual manner. In the case of air pressure loss in the air springs 314, i.e. during emergency operation, the vehicle body B is lowered onto the emergency springs 316. Then, let us assume that the bogie 300 encounters a section of twisted rails such that one of the emergency springs 316 is subjected to a higher load than the other opposite emergency spring 316. Thanks to the inventive hydraulic load balance device 319, this excess load is transferred from one longitudinal side 304 to the other longitudinal side 306 of the bogie 300, resulting in a lowering of the emergency spring 316 with the higher load and a rising of the emergency spring 316 with the lower load. The rising and lowering movement in opposite directions of the emergency springs 316 is indicated by the arrows dz. More precisely, as a reaction to the excess load, the corresponding piston 320 moves downward inside its pressure chamber 322, thus pushing hydraulic liquid L out of this pressure chamber 322, through the hydraulic pressure balancing line 324 (indicated by arrow F) and into the opposite pressure chamber 322. The additional hydraulic liquid L in the opposite pressure chamber 322 then pushes the corresponding piston 320 upwards. Thanks to this load balancing, the bogie 300 can adapt to the rail twist, which prevents derailing.
[0021] In the case of a failure of the hydraulic load balance device 319, e.g. by a loss of hydraulic liquid L, the pistons 320 will move down to the bottom 328 of the pressure chambers 322. Preferably, the bogie 300 is equipped with a failure sensor that can detect such a breakdown of the hydraulic load balance device 319. The readout of the failure sensor may be displayed to the driver.
[0022] Figures 4 and 5 show how the secondary suspension system 308 of Figure 3 can be implemented in a bogie requiring four suspension points. Secondary suspension system 308 is simply duplicated on the bogie. In a first variant shown in Figure 4, we have two spring assembly pairs P1, P2 whose hydraulic pressure balancing lines 324 are hydraulically separated. In a second variant shown in Figure 5, we have two spring assembly pairs P1, P2 whose hydraulic pressure balancing lines 324 are hydraulically interconnected via a hydraulic connection line 332.
[0023] In the inventive secondary suspension system, the emergency springs are arranged directly below the air springs. Hence, a separate emergency spring arrangement in the centre part of the bogie, as shown in Figure 2, and a corresponding special design of the vehicle body underframe and of the bogie frame is no longer necessary.
- a bogie frame (302) having two opposite longitudinal sides (304, 306); and
- a secondary suspension system (308) located on the bogie frame (302),
wherein the secondary suspension system (308) includes:
- at least two spring assemblies (310, 312) including an air spring (314) and equally distributed on both longitudinal sides (304, 306) of the bogie frame; and
- an emergency spring device (311) operating in case of air pressure loss in the air springs (314) and having an emergency spring (316) within each spring assembly (310, 312),
characterised in that the emergency spring device (311) comprises a load balance device (319) adapted to, during operation of the bogie (300) as a vehicle body support and in case of air pressure loss in the air springs (314), balance the loads between emergency springs (316) on opposite longitudinal sides (304, 306) by moving these emergency springs (316) in opposite directions, and thus enable a relative rolling movement between the bogie (300) and the vehicle body (B).- for each spring assembly (310, 312), a hydraulic piston (320) connected thereto;
- for each spring assembly (310, 312), a hydraulic pressure chamber (322) supporting the spring assembly and slidingly receiving its hydraulic piston (320); and
- for each pair (P1, P2) of spring assemblies (310, 312) on opposite longitudinal sides (304, 306), a hydraulic pressure balancing line (324) hydraulically connecting the two hydraulic pressure chambers (322) of the two spring assemblies (310, 312).