EP3409561B1

EP3409561B1 - A switch machine for a railroad switch and system for moving the switch points of a railroad switch equipped with such switch machine

Info

Publication number: EP3409561B1
Application number: EP18174726.2A
Authority: EP
Inventors: Alessandro BECCARISI; Maurizio Biagiotti
Original assignee: Silsud Srl
Current assignee: Silsud Srl
Priority date: 2017-05-31
Filing date: 2018-05-29
Publication date: 2020-04-15
Anticipated expiration: 2038-05-29
Also published as: IT201700059882A1; EP3409561A1

Description

Field of the invention

The present invention relates to railway technical field and in particular relates to an improved switch machine for railroad switches, in particular for high-speed railway lines.

Description of the prior art

As known, the switch machines of the railroad switches generally provide at least one shifting actuator, which translates, by movement transmission means, the switch points of the railroad switch between two limit positions. More precisely, at the above mentioned limit positions, one switch point is drawn close to the respective switch stock rail and is, therefore, called closed switch point, whilst the other switch point is spaced from the respective switch stock rail and is called, therefore, open switch point. At the opposite limit position, instead, the opposite situation occurs, and, therefore, the switch point that in the previous limit position was the closed-by switch point, is arranged at a predetermined distance from the respective switch stock rail and, therefore, becomes the far-removed switch point, whilst the switch point that was previously far-removed is arranged close to the respective switch stock rail and, therefore, becomes the closed-by switch point.
The movement from a limit position to the other is caused, as above disclosed, by an actuator, for example a hydraulic actuator having a predetermined actuation stroke arranged along an actuation direction.
The switch machines of known type, furthermore, provide locking/unlocking members, also known as switch point lock means, that block the switch points in one of the above disclosed limit positions. Generally, the switch point lock means are moved from an unlocking configuration to a locking configuration through an overstroke of the actuator along the actuation direction that is known as "overlapping".
A circumstance that can occur in a railroad switch is that an obstacle, for example a stone, interposes between a switch point and the respective rail stock, thus obstructing the correct movement of the railroad switch, and in particular the displacement of the switch point next to the respective rail stock. This situation could be not detected by the control system of the railroad switch in spite of the fact that the switch point is subjected to a bending owing to the presence of the obstacle between the switch point and the rail stock. This condition can be dangerous, particularly in the high-speed railway lines, because the train could run on a railroad switch that is not arranged in the correct geometry.
In light of the above, the railroad switches of prior art are not able to satisfy the necessary requirements for safety.
An example of railroad switch having the above mentioned drawbacks is, for example, described in EP2418135 .

Summary of the invention

It is therefore an object of the present invention to provide a switch machine that is able to overcome the above disclosed drawbacks of the switch machines of prior art and in particular to immediately, and with a high level of accuracy, detect an obstacle between the switch point and the respective stock rail.
It is also an object of the present invention to provide a switch machine that is able to ensure safety both to passengers and trains passing for the corresponding railway line.
It is also an object of the present invention to provide a switch machine that allows to use a hydraulic control unit simplified with respect to those usually used in the prior art, in particular in switch machines of multi-point type.
It is a further object of the present invention to provide a system for moving the switch points of a railroad switch having the same advantages.
These and other objects are achieved by a switch machine for a railroad switch, according to the invention, that is equipped with:

a movement group configured to translate along a movement direction in a first displacement direction, or in a second displacement direction opposite to the first one, in order to alternatively move at least a switch point between two limit positions in which is, respectively, close to, or spaced from, a respective rail stock;
an actuation group configured to actuate said translation of said movement group along said movement direction, said actuation group comprising a hydraulic actuator, in particular a double-effect hydraulic actuator, having a hollow main body, or slider, provided with a longitudinal cavity and slidingly mounted on a fixed stem configured to define in said longitudinal cavity, a first and a second opposite pushing chambers, said movement group being caused to slide in said first, or in said second displacement direction, according to the pressure exerted by a working fluid in said first, or in said second pushing chamber;
a feeding group comprising a pumping device and configured to alternatively and selectively feed a predetermined constant flow of said working fluid in said first, and in said second, pushing chamber through a hydraulic feeding circuit, said feeding group arranged to feed said working fluid at a predetermined initial pressure pi corresponding to a pushing force Fi;
a locking/unlocking group arranged to move from a locking configuration, in which is arranged to prevent said movement group from translating, to an unlocking configuration, in which is arranged to allow said movement group to translate;

a control group configured to reduce said initial pressure pi of said working fluid within said first, or said second, pushing chamber, up to a predetermined value p*, in such a way to correspondingly reduce the pushing force exerted by said hydraulic actuator at a predetermined value F* to prevent said actuation group from further translating if an external force greater than said pushing force F* acts; and
an operating group configured to operate said control group when said actuation group, during said motion of said movement group along said movement direction, reaches a predetermined actuation position at which said switch point is positioned at a predetermined distance from the respective rail stock.

In particular, the predetermined distance d* is less than a predetermined threshold distance, in such a way to reduce the working fluid pressure up to the predetermined value p* only in proximity of said limit position.
Preferably, the above disclosed actuation position is the position in which the switch point, during its displacement by the movement group, is positioned at a distance from the respective stock rail equal to, or less than 30 mm, in particular equal to, or less than 25 mm, advantageously equal to, or less than 20 mm.
Other technical characteristics and the related embodiments of the present invention are defined by the dependent claims.
In particular, the technical solution according to the present invention is particularly advantageous in the case of a railroad switch provided with two, or more, switch machines. In fact, in this case, differently from the known systems, the present invention allows to detect a possible external force acting on the actuator that is due to the presence, between switch point and stock rail, of an obstacle, such as a stone, or a bolt and, therefore, to avoid bending of the switch point that is moved.
In a possible embodiment of the invention, once the moved switch point is positioned in the closed position, i.e. close to the respective rail stock, the control group is deactivated. Therefore, the pressure of the working fluid, from value p* can be brought again to the above disclosed initial value pi.
In particular, the above disclosed movement of the locking/unlocking group from the locking configuration to the unlocking configuration, and vice versa, is caused by an overstroke of the hydraulic actuator. Therefore, the increase of the working fluid pressure up to the initial value pi, allows to move the locking/unlocking group from said unlocking configuration to said locking configuration, by the above disclosed overstroke of the hydraulic actuator, applying the greatest available pushing force, i.e. the initial force Fi. Therefore, once has been verified that the switch point has been correctly drawn near the respective rail stock, obtained by a predetermined stroke of the hydraulic actuator at the reduced pressure p*, the successive step of switch lock, obtained by the above disclosed overstroke of the hydraulic actuator, can occur at the initial pressure pi, in such a way to assure that this step can be correctly and quickly carried out.
In particular, the above disclosed control group comprises:

a first control branch hydraulically connected to the first pushing chamber, said first control branch provided with a first control valve configured to reduce the pressure of said working fluid in said first pushing chamber up to the above disclosed predetermined value p*, by discharging a determined quantity of said working fluid through a first discharge branch, when the actuation group moves in said first direction;
at least a second control branch hydraulically connected to said second pushing chamber, said second control branch provided with a second control valve configured to reduce the pressure in said second pushing chamber, by discharging a determined quantity of said working fluid in a second discharge branch up to reach said predetermined value p*, when said actuation group moves in said second direction.

In an advantageous embodiment of the invention, the operating group provides:

a first opening/closing device configured to move between opening position and a closing position to hydraulically connect or disconnect said first control branch to said first discharge branch;
a second opening/closing device configured to move between an opening position and a closing position in order to hydraulically connect or disconnect said second control branch to said second discharge branch.

In particular, the operating group can comprise, furthermore, an activation device associated to each said opening/closing device. More in particular, the activation device is configured to cause said first, or said second, opening/closing device to move from said closing position to said opening position when said actuation group reaches said actuation position during the motion in the first sliding direction, and the movement from the opening position to the closing position during the motion in the second sliding direction.
More in particular, the activation device is configured to mechanically operate the movement of the first, or the second, opening/closing device from the closing position to the opening position, when, during the sliding along the movement direction, the hollow main body of the hydraulic actuator reaches the above mentioned predetermined actuation position, during the displacement of the switch point close to the respective rail stock. Instead, during the motion in the opposite direction, i.e. during the displacement of the switch point away from the respective rail stock, the activation device mechanically operates the opening/closing device to move from the opening position to the closing position.
Advantageously, each activation device can be a cam member.
Preferably, the hydraulic feeding circuit comprises:

a first feed branch hydraulically connected to said first pushing chamber, said first feed branch associated to a first flow adjusting device configured to feed said predetermined constant flow of working fluid in said first pushing chamber;
a second feed branch hydraulically connected to said second pushing chamber, said second feed branch associated to a second flow adjusting device configured to feed said predetermined constant flow of working fluid in said second pushing chamber;

Preferably, the hydraulic feeding circuit is, furthermore, provided with a pressure detection group configured to detect the pressure values in the first and in the second feed branch, in such a way to monitor the trend of pressure over time P(ti) and to verify that said control group is correctly working.
Furthermore, a flow adjusting group can be provided configured to adjust the flow of working fluid in said first and in said second pushing chamber of said hydraulic actuator.
In particular, the flow adjusting group comprises a first and a second adjustment branch hydraulically connected one to the other, respectively, to the first and to the second pushing chamber.
More in particular, each adjustment branch provides a respective flow adjusting device to adjust the flowrate of the working fluid discharged by the first, or the second, pushing chamber of the hydraulic actuator through a discharge branch. This can comprise, or not, the chamber opposite to the chamber, which is causing the thrust.
In a preferred embodiment of the invention, the control group and the operating group are integral to the hollow main body of the hydraulic actuator. In the case that the flow control group is also provided, also this and the additional operating group can be integral to the hollow main body, or slider, of the hydraulic actuator.
Advantageously an additional operating group is furthermore provided configured to operate the flow adjusting group.
Preferably, the additional operating group is arranged to operate the flow adjusting group at a predetermined operating position of the actuation group, advantageously at a plurality of operating positions.
Advantageously, the additional operating group is arranged to operate the flow adjusting group when the locking/unlocking group is actuated to move from the locking configuration to the unlocking configuration and/or to move from the unlocking configuration to the locking configuration.
According to another aspect of the invention, a displacement system of the switch points in a railroad switch comprises a plurality of switch machines and wherein at least a switch machine of said plurality has the above described technical characteristics.
In particular, the above disclosed plurality of switch machines is hydraulically connected to a same feeding group configured to feed a predetermined constant flow of working fluid in a hydraulic feeding circuit. More in particular, the above disclosed plurality of switch machines is associated to a plurality of hydraulic actuators having respective hollow main bodies each of which slidingly mounted on a respective fixed stem configured in such a way to define a first and a second pushing chamber and configured to move in synchronized manner.

Brief description of the drawings

The invention will now be shown with the following description of its exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings in which:

Fig. 1 diagrammatically shows a front view partially sectioned, in order to highlight some constitutive elements, of a switch machine according to the invention in correct working conditions;
Fig. 2 shows a first hydraulic scheme according to the invention for moving the switch machine of Fig. 1;
Fig. 3 diagrammatically shows a plan view of a detail of a part of a railroad switch when the circumstance prejudicing its correct working occurs;
Fig. 4 shows an enlargement of the railroad switch portion of Fig. 3 where the potentially dangerous circumstance occurs;
Fig. 5 shows a first alternative embodiment provided by the invention for the hydraulic scheme of Fig. 2;
Fig. 6 diagrammatically shows a longitudinal section of a possible embodiment of the double-effect hydraulic actuator, which carries out the translation of the movement group;
Fig. 7 shows another alternative embodiment provided by the invention for the hydraulic scheme of Fig. 2;
Fig. 8A diagrammatically shows a multi-point railroad switch at which a determined number of switch machines according to the present invention can be installed;
Figs. 8B and 8C show an enlargement of two different switch machines of the railroad switch of Fig. 8A in order to highlight some geometric characteristics;
Fig. 9A shows in a perspective view an alternative embodiment of the hydraulic actuator according to the invention;
Fig. 9B shows the hydraulic actuator of Fig. 9A along a longitudinal section in order to show some characteristics;
Fig. 10 diagrammatically shows a plan view of an alternative embodiment of the switch machine of Fig. 1;
Fig. 11A diagrammatically shows a perspective front view of the switch machine of Fig. 1;
Fig. 11B shows an enlargement of a part of Fig. 11A in order to highlight some technical characteristics;
Fig. 11C shows an enlargement of a part of Fig. 11A in order to show an alternative embodiment of the control arms with respect to those shown in Fig. 10B;
Fig. 12 diagrammatically shows a perspective rear view of the switch machine of Fig. 9A;
Fig. 13 diagrammatically shows a front view partially sectioned of the locking/unlocking group, according to the invention, in a locking configuration;
Fig. 14 shows an enlargement of the engagement portion of the movable body and of the respective engagement seat of the locking/unlocking group of Fig. 13;
Fig. 15 shows a perspective view of the switch machine according to the invention with the locking/unlocking group in a locking configuration, corresponding to the case in which the closed switch point is the right switch point;
Fig. 16 shows in detail a front view partially sectioned of the control device according to the invention in an allowing position in which allows the locking/unlocking group to be unlocked, and therefore the movement rod to translate;
Fig. 17 shows a front view partially sectioned of the control device of Fig. 16, but in a preventing position in which prevents the locking/unlocking group from moving from the unlocking configuration to the locking configuration;
Figs. 18 and 19 show the locking/unlocking group in two different unlocking configurations in which the translation of the same can occur;
Fig. 20 shows the locking/unlocking group in a locking configuration alternative to the locking configuration of Figs. 14 and 15, i.e. in the case in which closed the switch point is the left switch point.

Detailed description of some exemplary embodiments of the invention

As diagrammatically shown in Fig. 1, a switch machine 1 for a railroad switch 300, according to the present invention, essentially, provides a movement group comprising at least a movement rod 20. This, in the case of a mobile crossing, is engaged to one switch point only at one of its end. Instead, in the case in which the switch machine 1, moved according to the invention, is provided at the switch points frame, the movement rod 20 is engaged, at opposite ends 21 and 22, respectively, to a first and to a second switch point 101 and 102 through respective movement transmission members.
In particular, the movement group 20 is arranged to translate along a movement direction 120 in order to cause a movement of the only one switch point fixed to it in the case of the crossing mobile, or of the first and of the second switch point 101 and 102, in the case of the switch points frame, between two limit positions. In this way, depending on whether the movement group 20 slides along the above disclosed movement direction 120, in a first direction, or in a second direction, opposite to the first, blade 101, 102, is positioned between a position closed to the respective stock rail 111, or 112, whereby is called closed switch point, and, therefore, the other switch point 102, or 101, is positioned in a position spaced from the respective stock rail 112, or 111, whereby is called open switch point, and vice versa.
It is, then, provided an actuation group 70 arranged to actuate the translation of the movement group 20 along the above disclosed movement direction 120. More precisely, as shown in detail in Fig. 6A, the actuation group 70 comprises a hydraulic actuator 71, for example a double-effect hydraulic actuator, provided with a fixed stem 72 supported at opposite ends by supports 76a and 76b.
Although in the figures a double-effect hydraulic actuator 71 is always shown, a first and a second hydraulic actuator can be also provided, each of which provided, respectively, with the first and with the second pushing chamber 77 and 78, and operated in order to move the movement group 20 in a respective translation direction along the movement direction 120.
The actuator 71 provides, furthermore, a hollow main body 75 having a longitudinal cavity 79 and slidingly mounted on the fixed stem 72. This is configured in such a way to separate the longitudinal cavity 79 into a first and a second opposite pushing chamber 77 and 78. In particular, the movement group 20 is caused to slide in the above disclosed first direction, or in the above disclosed second displacement direction, according to the pressure exerted in the first and/or in the second pushing chamber 77, or 78, by the working fluid. More precisely, according to the invention, a feeding group 210 feed a predetermined constant flow of working fluid alternatively, and selectively, in the first, or in the second pushing chamber 77 and 78. In particular, the feeding group 210 provides a hydraulic control unit 200 comprising, for example, a pump 205 operated by a motor 206, schematically shown in the figure 2, 5 and 7 with blocks, that feed the working fluid at a predetermined initial pressure pi.
The switch machine 1 provides, furthermore, a locking/unlocking group 50 arranged to move from a locking configuration, in which prevents the movement group in particular the movement rod 20, from translating along the movement direction 120, to an unlocking configuration, in which, instead, allows the above disclosed translation. More in particular, the locking/unlocking group 50, also known as switch lock group, is configured in such a way to arrange itself in the locking configuration when the actuation group 70 is arranged in a position such that the switch point 101, or 102, is arranged in a position closed to the respective stock rail 111, or 112.
According to the invention, furthermore, the switch machine 1 is equipped with a control group 220 configured to reduce the pressure of working fluid from the above disclosed value pi up to a predetermined value p*. In particular, the pressure value p* is set in such a way to correspondingly reduce the pushing force exerted by the hydraulic actuator 71. In this way, if between switch point 101, or 102, and respective stock rail 111, or 112, an obstacle is present and, therefore, if the external force acting on the hydraulic actuator 71 is higher than a predetermined value, the further stroke of the hollow main body 75 is impeded and therefore the switch railroad 300 stops and signal the danger. At the same time, the pushing force corresponding to pressure p* is, however, sufficient to allow the switch point to be positioned in the limit position, if the above disclosed situation does not occur.
More in particular, the pressure reduction from the initial value pi up to the above disclosed value p* is carried out by control group 220 by discharging a determined quantity of working fluid from the first, or the second, pushing chamber 77, 78, depending on which of them is fed by feeding group 210, i.e. according to the sliding direction of the hollow main body 75 and, therefore, of the movement group 20. For example, with reference to figure 2, if the sliding direction is towards the right, i.e. the direction that brings the switch point 102 in the position of closed switch point, the working fluid is discharged from the first pushing chamber 77, through a first discharge branch 225. This can comprise the second chamber 78 operating in discharge mode, (continuous line 225a), or can bypass the same (hatched line 225b in the figure). More in particular, the switch machine 1, according to the invention, provides an operating group 231, 232, configured to operate the control group 220, when the actuation group 70 reaches a predetermined actuation position. In particular, in the actuation position, switch point 101, or 102, moved towards the respective stock rail 111, or 112, is positioned near the respective stock rail 111, or 112, i.e. is positioned at a distance from this less than a predetermined threshold distance d*. This can be, for example, equal to, or less than 30 mm, advantageously equal to, or less than 25 mm, preferably equal to, or less than 20 mm. However, the threshold distance d*, in general, depends on the geometry of the railroad switch, on the position of the switch machine with respect to the switch railroad, on the material of which the switch point is made of, and on other constructive parameters.
The technical solution above disclosed, and adopted by the present invention, allows to prevent dangerous situations that could cause the train to go off the rails, if an obstacle, for example a stone 150, is present between switch point and stock rail (see figures 3 and 4). This circumstance, in fact, in particular if occurs between two successive switch machines 1a and 1b (see figure 3) is not detected by control systems of prior art. In fact, in the solutions according to the prior art, the pressure of working fluid into the feeding circuit 210 is constant and high enough to bring, however, the movement groups 20a and 20b of two successive switch machines 1a and 1b to the limit position, also if an obstacle is present 150. Therefore, the railroad switch is not able to detect the obstacle even if the bending of the switch point is such to cause the running train to go off the rails.
Instead, the present invention, thanks to the above disclosed mechanism, allows to immediately detect the obstacle 150 and to promptly operate in order to close the switch railroad and communicate the malfunction, in such a way to immediately bring in safe the line. The fact that an operating group is, furthermore, provided which opens the discharge circuit to reduce the pressure up to a value p*, only in proximity of the respective stock rail, allows, in particular, to optimize the mechanism, because it provides to verify the practicability of the switch railroad only if the obstacle 150 is present at a highly critical zone, i.e. only if the obstacle is positioned near stock rail 111, 112.
Still with reference to figure 5, the control group comprises a first control branch 221 hydraulically connected to first pushing chamber 77 and provided with a first control valve 241 configured to reduce pressure of working fluid in the first control branch 221 comprising la first pushing chamber 77. As above anticipated, the pressure reduction is obtained by discharging a predetermined quantity of working fluid in a discharge branch 225, comprising, or not, the second pushing chamber 78, until the pressure reaches the above disclosed predetermined threshold value p*. The control group 220 comprises, furthermore, at least a second control branch 222 hydraulically connected to second pushing chamber 78 and provided with a second control valve 242, which, analogously to what above described for the first control valve 241, is configured to reduce the pressure value of the working fluid in the second branch 222, by discharging a predetermined quantity of working fluid through the second discharge branch 226, comprising, or not the first pushing chamber 77, until the pressure reaches the above disclosed predetermined threshold value p*.
As it can be easily understood, the first control branch 221 is opened by respective operating group 231, when the actuation group 70 slides in the first direction, i.e. with reference to figure 5, from left to right, instead the second control branch 222 is opened by respective operating group 232, when the actuation group 70 slides in the second direction, i.e. from right to left.
In particular, the operating group provides a first opening/closing device 231 configured to move between an opening position and a closing position to hydraulically connect or disconnect the first control branch 221 to the first discharge branch 225, and at least a second opening/closing device 232 configured to move between an opening position and a closing position to hydraulically connect or disconnect the second control branch 222 to a second discharge branch 226.
In a preferred embodiment, diagrammatically shown in figure 6B, the operating group a determined number of activation devices, each of which associated to a respective opening/ closing device 231, 232. Each activation device can comprise two parts, and precisely a first part 175a integral to the hollow main body 75, and a second part 175b fixed. More in detail, the operating group is arranged to mechanically operate the movement of the first, or the second, opening/ closing device 231, 232, from the closing position to the opening position, once the above disclosed predetermined actuation position is reached. In particular, when the actuation group 70 moves the switch point 101, or 102 to move it in the respective position closed to the respective stock rail 111, or 112, fixed part 175b of the activation device acts on the first part 175a, in such a way to cause the opening/ closing device 231, or 232, to move in the opening position. Instead, when the actuation group 70, and, therefore, the movement group 20 integral to it, moves the switch point 101, or 102, still along direction 120, but in the opposite direction with respect to the previous case, i.e. to move it in the position of open switch point, the fixed part 175b of the activation device mechanically acts on part 175a integral to the hollow body 75 in order to cause the opening/ closing device 231, or 232, to move in the closing position.
The hydraulic feeding circuit 210 can provide a first feed branch 211 hydraulically connected to first pushing chamber 77, and a second feed branch 212 hydraulically connected to second pushing chamber 78. More precisely, both the first feed branch 211, and the second feed branch 212 are associated to a respective flow adjusting device 215, 216. These are configured to feed a predetermined constant flow of working fluid in the respective feed branch 211, 212, and, therefore, in a respective pushing chamber 77, 78. As it can be easily understood, according as the branch to be hydraulically connected to pumping device 205, is the first feed branch 211, or the second feed branch 212, the corresponding flow adjusting device 215, or 216, will be open and, therefore, it will provide to feed the above disclosed constant flow to the respective pushing chamber 77, 78, whilst the other flow adjusting device 216, or 215, will be closed, for example positioned in a stand-by configuration by a by-pass, in order not to discharge the working fluid downstream of the same.
For example, if the movement rod 20 has to slide towards the right, i.e. if the switch point to be drawn near the respective stock rail is the switch point 101 and, therefore, if the pushing chamber of the actuator 71 to be fed with the working fluid is the first pressure chamber 77, the first flow adjusting device 215 is opened, whilst the second flow adjusting device 216 is closed.
In the preferred embodiments shown in the figures 5 and 7, the feeding circuit 210 provides, furthermore, a pressure detection group 250. This comprises, for example, a pressure transductor, configured to detect the pressure values at least in one between the first and the second feed branch 211, 212. In this way, it is possible to verify that the control group is correctly working, and in particular the control valves, and that the above disclosed reduction of pressure of the working fluid is really obtained. In an advantageous embodiment of the invention, the pressure detection group 250 provides at least a pressure transductor 255 configured to detect, alternatively, the pressure in the first feed branch 211 and in the second feed branch 212, according to the pushing chamber fed with the working fluid. In an embodiment of the invention, a first and a second pressure transductors 251 and 252 are provided, both configured to measure the pressure both in the first and in the second feed branch 211 and 212. In this way it is possible to obtain a redundant measurement of pressure.
In figure 7, a further embodiment of the switch machine 1 according to the invention is diagrammatically shown. In this case a flow adjusting group 260 is provided comprising a first and a second branch 261 and 262, hydraulically connected, respectively, to the first and to the second pushing chamber 77 and 78. In particular, each adjustment branch 261, 262, provides a respective additional flow adjusting device 217, 218, configured to adjust the flow of working fluid discharged from the first, or from the second, pushing chamber 77, 78, of hydraulic actuator 71, through a respective additional discharge branch 275, or 276. As above disclosed with reference to the discharge branches 225 and 226 concerning pressure adjustment, also the additional discharge branches 275 and 276 can comprise the chamber opposite to the one that is fed, or can bypass it (branches with hatched line in figure 7).
Still as shown in figure 7, each adjustment branch 261, 262, advantageously furthermore provides a respective one- way valve 247, 248. The additional discharge branch can comprise the chamber opposite to the one in which the working fluid is fed that in this working condition is arranged in a discharge configuration. In the case shown in figure 7 the additional discharge branch comprises the pushing chamber 78.
Furthermore, an additional operating group, for example a first and a second additional opening/ closing device 233 and 234, can be provided at each flow adjustment branch 261 and 262. The additional operating group 233 and 234 is configured to operate the first, or the second, flow adjustment branch 261, 262, when a predetermined operating position of the actuation group 70 is reached, i.e. of the hollow main body 75. In a possible embodiment of the invention, the above disclosed predetermined actuation position of the flow adjustment branch 261, or 262, can be, for example, the position of the movement group 20 corresponding to the beginning of the step of movement from the locking configuration to the unlocking configuration of locking/unlocking group, i.e. when the switch lock group is unlocked.
In this way, it is possible to adjust as desired the flow of working fluid fed in the first, or in the second, pushing chamber 77, or 78, of the hydraulic actuator 71.
This technical solution is particularly advantageous in the case in which the railroad switch 300 is of multi-point type, i.e. comprises a plurality of switch machines, for example 4 switch machines 1a, 1b, 1c and 1d, hydraulically connected to the same pumping device 200 of the fluid in pressure through a respective branch of the hydraulic circuit 210 (see figure 8A). In particular, each switch machine 1a-1d is associated to a respective hydraulic actuator 71a-71d. More precisely, the hydraulic actuators 71a-71d are configured to move in a synchronized way, in particular in order to simultaneously operate the movement of the respective locking/unlocking groups from the locking configuration to the unlocking configuration, and to displace the first, or the second switch point 101, 102, in such a way to avoid jamming, or bending.
According to a first embodiment of the invention, the above disclosed displacement system of the switch points provide the above disclosed plurality of hydraulic actuators 71a-71d, in particular double-effect hydraulic actuators, associated to a plurality of first and second pushing chambers 77a-77d and 78a-78d. In particular, the above disclosed plurality of hydraulic actuators 71a-71d is dimensioned, essentially in terms of cross-section and length of the pushing chambers and the fixed stems, according to the position in the railroad switch 300, in such a way to obtain the above disclosed synchronized motion with a constant flow of the working fluid. In particular, as known and diagrammatically shown in the figures 7B and 7C, the size of the hydraulic actuators 71a-71d, in terms of length and/or cross-section, increases in a predetermined way, going away from the crossing C of railroad switch 300.
Depending on the type of railroad switch and its constructive characteristics, however, it is possible that the use of only one constant flow of the working fluid could lead to a measurement of the hydraulic actuators, in particular of those farthermost from the crossing C of the switch railroad, such that it would be not favourable, in particular such that it would be not possible to install the same at the switch railroad 300. In these cases, therefore, it is advantageous, if not necessary, to adopt the hydraulic scheme of figure 7. This hydraulic scheme, in fact, thanks to the presence of the above mentioned flow adjusting devices 217 and 218, allows to adjust the working fluid flow in each hydraulic actuator 71a-71d of switch railroad and, therefore, allows to measure the different hydraulic actuators independently from the maximum flow of switch railroad, i.e. the flow fed by feeding group 210. In particular, with reference to the hydraulic scheme of figure 7, once a determined maximum constant flow Q_max have been set that is fed by pumping device 205 in the hydraulic circuit 210, the flow of working fluid in each actuator 71 of railroad switch 300 can be, then, easily reduced "by discharging" the flow in excess with respect to the desired one, through the discharge branch 275, or 276, of the above disclosed flow adjustment circuit 260. The flow, reduced as above described, can be, in case, increases by closing again the flow discharge branch 275, or 276. In this way, is, therefore, possible to easily adjust the flow of each hydraulic actuator 71a-71d, in such a way to synchronize the motion of the different actuators of the railroad switch 300 and, at the same time, to install them at the switch railroad (see figures 8A-8C).
According to a further embodiment of the invention, diagrammatically shown in the figures 9A and 9B, the control group 220, in particular the control valves 241 and 242, and the respective actuation devices 231, 232 of the control branches, can be provided integral to the hollow main body 75 of the hydraulic actuator 71.
In the case in which also the additional flow adjustment group, shown as an example in figure 9A, is provided, also the additional flow adjustment devices 217 and 218 and the respective actuation devices 233 and 234 can be integral to the hollow main body of actuator 75.
As diagrammatically shown in figure 9B, furthermore, the feed branches and the discharge branches, of which only some portions is shown in the figures, both of the adjusting valves 241 and 242 and of the additional adjustment devices 217 and 218, or at least a part of them, can be made in the hollow main body 75.
In this way a highly compact hydraulic circuit is obtained that provides the above disclosed pressure and flow adjustment devices.
The hydraulic schemes above disclosed with reference to figures from 1 to 8C, can be advantageously used for operating the switch machines of known type, or switch machines as described in the following.
In particular, with reference, for example, to figure 10, a switch machine 1 that can be operated by the device above disclosed, can be advantageously of the type having sizes that allow it to be installed at a rail sleeper 160 of a railway line. More in particular, the switch machine 1 can provide a first control rod 31 and a second control rod 32, for example arranged coaxially to each other, arranged to translate independently one from the other, along a direction parallel to the above disclosed movement direction 120. More precisely, the first and the second control rod 31 and 32 have a respective end 31a, 32a, respectively, fixed to the first switch point, or left switch point, 101 and to the second switch point, or right switch point, 102.
In particular, the first and the second control rod 31 and 32 are fixed, respectively, to the first and to the second switch point 101 and 102 in engagement points B and B' that are different from the engagement points A and A' at which the ends 21 and 22 of movement rod 20 are fixed to the switch points 101 and 102. More in particular, the first and the second control rod 31 and 32 are fixed to the switch points 101 and 102 by movement transmission members 38a, 39a different from the movement transmission members 40a and 40b through which the ends 21 and 22 of the portions 20a and 20b of movement rod 20 are fixed to the switch points 101 and 102.
The ends 31b and 32b opposite to the ends 31a and 32a of each control rod 31 and 32 are, then, supported by a support body 34.
The actuation group 70 provides, furthermore, a movable body 41, in particular housed within a housing 42, integral to the movement rod 20. More in particular, each portion 20a and 20b of movement rod 20, at the opposite side of the above disclosed ends 21 and 22, provides another end 23 and 24 integral to a containment body 45, which provides the above disclosed housing 42 for the movable body 41. In particular, the movable body 41 and the cam portion 73 are configured in such a way that the translation of hollow main body 75 and, therefore, of cam portion 73 integral to it, along the fixed stem 72, causes the movable body 41 to move from a locking configuration, in which is arranged to engage in a fixed body 43, in particular integral to a rail sleeper 160 of the rail line at which the switch machine 1 is positioned, in order to prevent the movement rod 20, or each of its portion 20a, 20b, from translating and an unlocking configuration, in which the movable body 41 is not engaged to the fixed body 43 and is arranged to integrally translate with the movement rod 20, or with each portion 20a, 20b, along a movement direction 120. The movement from the unlocking configuration to the locking configuration of the locking/unlocking group 50 is caused, in particular, by an overstroke of actuator 71 along an actuation direction parallel to the movement direction 120 of movement rod 20. In particular, the translation of hollow main body 75, and of cam portion 73 integral to it, along stem 72 of actuator 71, causes the movable body 41 to rotate about a rotational axis 141 orthogonal to the movement direction 120. In particular, the movable body 41 is pivoted to the containment body 45 at a pivot 44. In this way, the movement of movable body 41 is caused from the unlocking configuration (figures 18 and 19) to the locking configuration (figures 13-15) about the rotational axis 141. More precisely, the cam portion 73 provides a pushing surface 37 arranged to cooperate with at least a guide roll, for example 2 guide rolls 47 and 48, mounted free to rotate about a rotational shaft integral to the above disclosed movable body 41, in order to guide the motion of the movable body 41 within housing 42. In the embodiment shown in the figures, the pushing surface 37 provides a first and a second portion 37a and 37b having opposite inclinations and connected to a straight portion 37c, in such a way to substantially define a polygonal-shaped cam portion (see for example figure 18).
More precisely, at determined positions of movable body 41, the guide rolls 47 and 48 are arranged to be positioned into contact with the above disclosed pushing surface 37, which guides them upward, or downward, according to the translation direction of cam portion 73, thus causing, alternatively a translation along a movement direction 120, or a rotation in clockwise direction, or in anticlockwise direction, of movable body 41 about rotational axis 141. In this way, the movable body 41, in particular a first engagement portion 41a, or a second engagement portion 41b, of the same, is caused to move towards inside, or outside (according to the direction of rotation), respectively in a first, or in a second, blocking seat 43a, 43b made in the fixed body 43, at the locking configuration, or at the unlocking configuration, respectively. In the embodiment shown in the figures 13-18 a control device 60 is, furthermore, provided is configured in such a way to prevent the movable body 41 from rotating about the rotational axis 141 and, therefore, to move from the unlocking configuration to the locking configuration, if both the control rods 31 and 32 are arranged in the respective predetermined correct positions. More in particular, the control device 60 impedes the engagement portions 41a, or 41b, of movable body 41, depending on which of the first, or the second, switch point 101, 102, is the closed switch point in that operative condition, to engage in the respective blocking seat 43a, or 43b of fixed body 43.
The above disclosed condition, that is the non-displacement of both the control rods 31 and 32 in the predetermined correct positions, can occur, for example, because one of the two switch points 101, or 102, is disengaged from the movement rod 20. In this situation in fact, in the switch machines of prior art, the movement rod continues, however, to be moved along the above disclosed movement direction of actuation group and, therefore, the system does not detect the malfunction. The technical solution according to the present invention, instead, allows to detect the above disclosed malfunction, because the control device 60 detects a relative motion between the control rod 31 and the containment body 45, to which the support body 34 is integral to, and does not allow, therefore, to the locking/unlocking group 50, to move from the unlocking configuration to the locking configuration. In fact, if one of the two switch points, in particular if the closed switch point, owing to the above disclosed mechanical damage, or for any other reason, is not really displaced from movement rod 20, and, therefore, remains closed to the respective rail stock, or however, it is not displaced in the correct position of closed switch point, the control rod 31, or 32, fixed to it at an end is not positioned in the predetermined correct position.
Therefore, since the control device 60, owing to the non-detection of the correct position of the control rods 31, 32, does not allow the locking/unlocking group 50 to move in the locking configuration, the switch machine 1, according to the invention is able to increase the level of safety of the railroad line at which is installed.
In the embodiment shown, in detail, in figure 11B, the control device 60 provides a first and a second lowered portion 35 and 36, each of which made at a predetermined position of a respective control rod 31, 32. As shown, in particular, in the figures 11A, 11B, 11C, 16 and 17, the control device 60 provides, furthermore, a first and a second control arm 65 and 66 integral to the movable body 41, in particular at the opposite sides, advantageously at, or in proximity of, the engagement portions 41a, 41b. More in particular, the control arms 65 and 66 can protrude from the containment body 45 through respective apertures, or windows, 46a and 46b towards the control rods 31 and 32. In this way, the control arms 65 and 66 are arranged to position in a respective lowered portion 35, 36 of a respective control rod 31, 32, allowing the movable body 41 to rotate about the rotational axis 141 in order to move from the unlocking configuration to the locking configuration, only if both the first and the second control rod 31 and 32 are arranged in the respective above disclosed predetermined correct position with respect to the locking/unlocking group 50. Instead, if, for example owing to the disengagement of a switch point from the movement rod, one between the two control rods 31, or 32, is not in the correct position, rotation of movable body 41 caused by the pushing surface 37 is impeded. In fact, the corresponding control arm 65, or 66, is not able to completely rotate owing to the greatest thickness of control rod 31, or 32, with respect to the lowered portion 35, or 36, and therefore, the engagement portion of the movable body 41 is not able to exit the blocking seat 43a, or 43b, of fixed body 43. In other words the control device 60 "does not permit" the locking/unlocking group 50 to move from the unlocking configuration to the locking configuration.
What above described is diagrammatically shown in the figures 16 and 17. In particular, as diagrammatically shown in figure 16, in normal working conditions, the ends 31b and 32b of the control rods 31 and 32 are spaced from each other of a predetermined distance d1. In this working configuration, the control device 60 moves in an allowing position, in which, it allows the locking/unlocking group 50 to move from the unlocking configuration to the locking configuration. Instead, if, for example as above described, owing to disengagement of the switch point from the movement rod 20, the switch point is not really moved, the control rod that is fixed to the same switch point, for example control rod 31 fixed to switch point 101, moves in the position of figure 17, in which impedes the locking/unlocking group 50 to move from the unlocking configuration to the locking configuration.
In the embodiment shown, for example, in the figures 11A and 11B, each lowered portion 35, 36, is a circumferential groove made on a respective control rod 31, 32. In particular, each control arm 65, 66 can have a contacting portion 67, 68 substantially "U"-shaped, or "V"-shaped, and has a first and a second end 67a, 67b and 68a, 68b arranged, in use, at opposite sides of a same control rod 31, 32 (figure 11B). In the alternative embodiment of figure 11C, instead, each contacting portion 67, 68, is made at a closed end. This solution assures to have a higher structural stiffness for the control arm 65, 66.
More precisely, when the above disclosed movable body 41 is positioned at the first locking configuration, i.e. when the engagement portion 41a is positioned at the blocking seat 43a, if the control rods 31 and 32 are positioned in the respective correct positions, the rotation of the movable body 41 about the rotational axis 141 is not impeded by the control device 60, and, therefore, the engagement portion 41a can disengage from the blocking seat 43a. This because the ends 67a, 67b and 68a, 68b of the control arms 65 and 66, during the rotation about axis 141 of movable body 41, to which they are fixed, arrange themselves in the respective lowered positions 35 and 36. More precisely, each first and second end 67a,67b, and 68a,68b of a same control arm 65, and 66, are arranged to alternatively and selectively position, in a same circumferential groove 35, or 36, but at the opposite side with respect to control rod 31, or 32, according to that the engagement portions 41a, 41b of the movable body 41 and the respective engagement seats 43a, 43b of the fixed body 43, are arranged in the first locking configuration (figures 13 and 14), corresponding to the situation in which the left switch point 102 is the closed switch point, or in the second locking configuration (figure 20), corresponding, instead, to the situation in which the left switch point 101 is the closed switch point.
Once the movement rod 20 is arranged in the correct position with the switch lock group in the locked configuration, i.e. with the locking/unlocking group 50 in the locking configuration, an electric control device of the position of the switch points is also provided, that is not shown in the figures for reasons of simplicity, but that is of known kind in the technical field.
Although it has been always considered the case in which the control device prevents the locking/unlocking group from moving from the unlocking configuration to the locking configuration when the control rods are positioned in the respective predetermined positions, the skilled person would have no difficulty, however, adjusting the solution according to the present invention also to the case in which the control device is configured in such a way to prevent the locking/unlocking group from moving from the locking configuration to the unlocking configuration in the same condition, i.e. when the control rods are not positioned in the respective predetermined positions.
The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention as claimed, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments.

Claims

Switch machine (1) for a railroad switch equipped with:
- a movement group (20) configured to translate along a movement direction (120) in a first displacement direction, or in a second displacement direction opposite to the first, to alternatively move, at least a switch point (101,102) between two limit positions in which switch point is, respectively, closed to, or spaced from, a respective rail stock;

- an actuation group (70) configured to actuate said translation of said movement group (20) along said movement direction (120), said actuation group (70) comprising at least a hydraulic actuator (71) having a hollow main body (75) provided with a longitudinal cavity (79) and slidingly mounted on a fixed stem (72) configured to define in said longitudinal cavity (79) a first and a second opposite pushing chambers (77,78), said movement group (20) being caused to slide in said first direction, or in said second displacement direction, according to the pressure exerted by a working fluid in said first, or in said second pushing chamber (77,78);

- a feeding group (210) comprising a pumping device (205) and configured to alternatively and selectively feed a predetermined constant flow of said working fluid in said first, and in said second pushing chamber (77,78), through a hydraulic feeding circuit (210), said feeding group (210) being arranged to feed said working fluid at a predetermined initial pressure pi corresponding to a pushing force Fi;

- a locking/unlocking group (50) arranged to move from a locking configuration, in which is arranged to impede said translation of said movement group (20), to an unlocking configuration, in which is arranged to allow said translation of said movement group (20);
said switch machine further providing:
- a control group (220) configured to reduce said initial pressure pi of said working fluid within said first, or said second, pushing chamber, up to a predetermined value p*, in such a way to correspondingly reduce the pushing force exerted by said hydraulic actuator (71) up to a predetermined value F* in order to prevent said actuation group from further sliding if an external force greater than said pushing force F* acts;
characterised in that an operating group (231,232) is, furthermore, provided configured to operate said control group (220) when said actuation group (70), during said motion of said movement group (20) along said movement direction (120), reaches a predetermined actuation position at which said switch point is positioned at a predetermined distance d* from the respective stock rail (111,112), with d* less than a predetermined threshold distance, in such a way to reduce said pressure of said working fluid up to said predetermined value p* in proximity of said limit position.
Switch machine for a railroad switch, according to claim 1, wherein said control group (220) comprises:
- a first control branch (221) hydraulically connected to said first pushing chamber (77), said first control branch (221) being provided with a first control valve (241) configured to reduce said pressure of said working fluid in said first pushing chamber (77) up to said predetermined value p*, by discharging a predetermined quantity of said working fluid through a first discharge branch (225), when said actuation group (70) moves in said first direction;

- at least a second control branch (222) hydraulically connected to said second pushing chamber (78), said second control branch (222) being provided with a second control valve (242) configured to reduce said pressure of said working fluid in said second pushing chamber (78) by discharging a determined quantity of said working fluid through a second discharge branch (226) up to reach said predetermined value p*, when said actuation group (70) moves in said second direction.
Switch machine for a railroad switch, according to claim 2, wherein said operating group (231,232) provides:
- a first opening/closing device (231) configured to move between an opening position and a closing position in order to hydraulically connect, or disconnect, said first control branch (221) and said first discharge branch (225);

- a second opening/closing device (232) configured to move between an opening position and a closing position in order to hydraulically connect or disconnect said second control branch (222) and said second discharge branch (226);

- an activation device (175a,175b) associated to each said opening/closing device (231,232) and configured to cause said first, or said second, opening/closing device (231,232) to move from said closing position to said opening position when said actuation group (70) reaches said actuation position, during the motion in said first direction, and from said opening position to said closing position when said actuation group (70) reaches said actuation position, during the motion in said second direction.
Switch machine for a railroad switch, according to any previous claim, wherein said predetermined distance d* is ≤30 mm, in particular d*≤25 mm, advantageously d*≤20 mm.
Switch machine for a railroad switch, according to any previous claim, wherein said hydraulic feeding circuit (210) provides a pressure detection group (255) configured to detect the pressure values in said first, or in said second, feed branch (211,212), in such a way to monitor pressure trend over time p(ti) and verify that said control group (220) is correctly working.
Switch machine for a railroad switch, according to any previous claim, wherein a flow adjusting group (260) is, furthermore, provided configured to adjust the working fluid flow into said first and into said second pushing chamber (77,78) of said hydraulic actuator (71), said flow adjusting group (260) comprising a first and at least a second adjustment branch (261,262) hydraulically connected, respectively, to said first, and to said second pushing chamber (77,78), each adjustment branch (261,262) equipped with a respective additional flow adjusting device (217,218) configured to adjust the flow of said working fluid discharged from said first, or from said second, pushing chamber (77,78) of said hydraulic actuator (71) through a respective additional discharge branch (275,276).
Switch machine for a railroad switch, according to claim 6, wherein an additional operating group (233,234) is, furthermore, provided configured to operate said first, or said second, flow adjustment branch (261,262) when predetermined operating positions are reached.
Switch machine for a railroad switch, according to claim 7, wherein said predetermined operating positions of said first and of said second flow adjustment branch (261,262), corresponds to the positions of said movement group (20) at which the movement of said locking/unlocking group (50) from said locking configuration to said unlocking configuration occurs.
Switch machine for a railroad switch, according to any previous claim, wherein at least said control group (220,241,242) and said operating group (231,232) are integral to said hollow main body (75) of said hydraulic actuator (71).
Switch machine for a railroad switch, according to claim 3, wherein said activation device (175a, 175b) is a cam member.
Switch machine for a railroad switch, according to any previous claim, wherein said hydraulic feeding circuit (210) is, furthermore, equipped with a pressure detection group (250) configured to detect the pressure values at least in one between said first and said second feed branch (211, 212).
Switch machine for a railroad switch, according to claim 11, wherein said pressure detection group (250) provides at least a pressure transductor (255) configured to, alternatively, detect, the pressure into said first feed branch (211) and into said second feed branch (212), depending on which pushing chamber is fed with said working fluid.
Switch machine for a railroad switch, according to claim 11, wherein said pressure detection group (250) provides a first and a second pressure transductor (251, 252) both configured to detect the pressure both in said first feed branch (211) and in said second feed branch (212), in such a way to carry out a redundant measurement of pressure.
Switch points displacement system in a railroad switch characterised in that it comprises a plurality of switch machines (1a-1d), according to any claims from 1 to 13, said plurality of switch machines (1a-1d) being hydraulically connected through respective feed branches, to the same feeding group (200) configured to feed a predetermined constant flow of said working fluid in said hydraulic feeding circuit (210), said plurality of switch machines (1a-1d) being associated to a plurality of hydraulic actuators (71a-71d) having respective hollow main bodies (75a-75d) slidingly mounted on respective fixed stems (72a-72d), each fixed stem (72a-72d) being configured in such a way to define in the respective hollow main body (75a-75d) a first and a second pushing chamber (77a-77d, 78a-78d), and wherein said feeding group (200) is configured to alternatively and selectively feed said plurality of first pushing chambers (77a-77d) and said plurality of second pushing chambers (78a-78d).
Switch points displacement system in a railroad switch characterised in that it comprises a plurality of switch machines (1a-1d), according to any claims from 1 to 13, said plurality of switch machines (1a-1d) being hydraulically connected to the same feeding group (200) configured to feed a predetermined constant flow of said working fluid in said hydraulic feeding circuit (210), said plurality of switch machines (1a-1d) being associated to a plurality of hydraulic actuators (71a-71d) having respective hollow main bodies (75a-75d) slidingly mounted on respective fixed stems (72a-72d), each fixed stem (72a-72d) being configured to define in the respective hollow main body (75a-75d) a first and a second pushing chamber (77a-77d, 78a-78d), said feeding group (200) being configured to alternatively and selectively feed said plurality of first pushing chamber (77a-77d) and said plurality of second pushing chamber (78a-78d), and wherein a plurality of flow adjustment groups is, furthermore, provided configured to adjust the flow of said working fluid fed into said plurality of hydraulic actuators (71a-71d), in such a way to move said plurality of hydraulic actuators (71a-71d) in a synchronized way.