Railway vehicles

Abstract

To provide a railway vehicle that reduces the possibility of derailment during an earthquake by suppressing vehicle sway and relative displacement between the car body and bogie, which cause a decrease in wheel load, and further by suppressing air leakage from the air springs. [Solution] The vehicle comprises a pair of air springs located between the vehicle body and the bogie, a pair of vertical vibration damping devices arranged in parallel with the air springs and capable of changing the generated force, and an earthquake detection means for detecting earthquakes. The vertical vibration damping devices can be switched between a ride comfort priority mode and an earthquake mode in response to a signal from the earthquake detection means, in which case the generated force is greater than that of the ride comfort priority mode. In the earthquake mode, the generated force on the extension side of the vertical vibration damping devices is smaller than the generated force on the compression side.

Description

Technical Field

[0001] The present invention relates to a railway vehicle that can improve the riding comfort of the railway vehicle during normal running and reduce the possibility of vehicle derailment or the like during an earthquake.

Background Art

[0002] In railway vehicles, various measures for suppressing derailment have been taken for the purpose of preventing the railway vehicle from derailing from the rail during an earthquake.

[0003] For example, as a measure for suppressing derailment, by attaching a "derailment prevention guard" inside the rail on the track side, it is possible to prevent the deviation of the axle in the left - right direction by the derailment prevention guard during large - displacement excitation caused by an earthquake or the like, and prevent locking derailment. Also, by attaching a "deviation prevention stopper" or "deviation prevention guide" on the vehicle side, in the event that the vehicle derails, it is possible to prevent the vehicle from deviating greatly from the track.

[0004] In addition to the above - mentioned derailment prevention guard and deviation prevention measures, the damping force characteristics of the left - right motion damper attached between the car body and the bogie are devised to generate a large force against the fast damper stroke speed generated during an earthquake, and suppress the left - right displacement between the car body and the bogie. A "seismic - countermeasure left - right motion damper" is known. Also, based on the same concept, the dampers for railway vehicles and the vibration - damping devices for railway vehicles described in Patent Document 1 and Patent Document 2 are for a variable - damping left - right motion damper attached between the car body and the bogie or a left - right motion damper attached in parallel with an actuator. They generate a large force against the fast stroke speed generated during an earthquake and suppress the left - right displacement between the car body and the bogie. "Damper for railway vehicle and vibration - damping device for railway vehicle" and "vibration - damping device for railway vehicle" have been proposed.

[0005] While the railway vehicle damper described in Patent Document 1 has both the damper and the actuator bear the force necessary for vibration damping during an earthquake, the railway vehicle vibration damping device described in Patent Document 2 reduces the load on the actuator by having the lateral damper bear a larger damping force, thus contributing to lowering the cost of the actuator.

[0006] On the other hand, regarding vertical vibrations during earthquakes, as described in Patent Document 3, a "railway vehicle" has been proposed in which vertical dampers are installed between the car body and the bogie, and when the relative displacement between the car body and the bogie exceeds a predetermined range, the valve of the vertical damper is switched to lock the damper, thereby suppressing the vertical displacement between the car body and the bogie.

[0007] Furthermore, focusing on vibrations in both vertical and horizontal directions, as described in Patent Document 4, a method has been proposed to suppress vibrations of the vehicle body by using a combination of dampers that dampen vertical, horizontal, and / or roll movements between the bogie and the vehicle body, and dampers that dampen vertical and / or roll movements of the bogie, and by combining these to control the generated force when an earthquake occurs. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Patent No. 6916696 [Patent Document 2] Japanese Patent Publication No. 2024-108368 [Patent Document 3] Patent No. 5377384 [Patent Document 4] Patent No. 4868911 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Most train derailments during earthquakes occur in areas where ground infrastructure has been damaged or deformed by strong seismic activity. On the other hand, as a result of improved ground infrastructure strength due to seismic reinforcement, train derailments are now also occurring in areas where the ground infrastructure has not been deformed.

[0010] For example, in cases of derailments caused by major earthquakes in recent years, the process leading to derailment is thought to be as follows: "Strong shaking of the track surface due to the earthquake caused the train body to roll, which lifted the left or right wheels, causing them to go over the rails and derail (rocking / derailment). Furthermore, the excessive deformation of the air springs due to the rolling of the train body caused air to leak, which exacerbated the derailment." In addition, "In some cases, the derailment prevention guides or obstacle deflector mounting arms were found to have come off the rails and derailed on some wheelsets. This may be because the derailment prevention guides, which were preventing derailment, went over the rails and derailed due to the continued earthquake shaking after the derailment, or because the obstacle deflector mounting arms or gearboxes fell onto the rails during the derailment and then derailed."

[0011] In recent derailment cases, although the trains were equipped with derailment prevention guides, it has been pointed out that these measures alone were insufficient to prevent the trains from derailing. The reason given for this is that "the air springs underwent excessive deformation due to the rolling of the train body, resulting in air leakage, which exacerbated the derailment."

[0012] In contrast, conventional earthquake-induced derailment countermeasures, such as installing derailment prevention guards and deviation prevention measures, are technologies that restrain the wheelset (bogie / car body) on the track as much as possible and do not suppress vehicle vibrations. Therefore, it is difficult to suppress air leakage caused by excessive deformation of the air springs due to the rolling of the car body.

[0013] Furthermore, among the countermeasures described in Patent Documents 1 to 4, those that implement some kind of countermeasure on the lateral damper are designed to be usable without switching damping force characteristics between normal and earthquake conditions, so the vibration damping effect during earthquakes is somewhat limited. Also, these are countermeasures using only the lateral damper or actuator, and cannot directly suppress the vertical displacement of the air spring when significant roll vibration occurs. In the method of locking the vertical damper when the vertical displacement between the car body and the bogie exceeds a certain level, the locking of the vertical damper is abrupt, so even if the damper is attached to the bogie and car body via an elastic material, an impact force will be applied. The method of using a combination of dampers that dampen the vertical, lateral, and / or roll motion between the bogie and the car body, and dampers that dampen the vertical and / or roll motion of the bogie, is desirable from the viewpoint of damping car body roll, vertical and lateral vibrations, because it controls both the lateral and vertical directions of the secondary spring. However, there are areas where further improvements can be made in practical use, such as countermeasures to prevent the damper from pulling up the bogie when it extends, and countermeasures for when the effective length of the damper has been fully utilized. In addition, while vertical vibration damping devices are currently limited to dampers, there is room for performance improvement through the use of other devices.

[0014] This invention has been made in view of the above circumstances, and its main objective is to provide a railway vehicle that actively improves ride comfort except during earthquakes, and during earthquakes suppresses vehicle sway (especially body rolling vibration) and relative displacement between the body and the bogie, which cause a decrease in wheel load, and further suppresses the occurrence of large vertical displacements of the air springs that could cause air leakage from the air springs, thereby reducing the possibility of the vehicle derailing. [Means for solving the problem]

[0015] To solve the above problems, the railway vehicle according to the present invention is a railway vehicle having a car body and a bogie that supports the car body, comprising a pair of air springs located between the car body and the bogie, a pair of vertical vibration damping devices arranged in parallel with the air springs and capable of changing the generated force, and an earthquake detection means for detecting earthquakes, wherein the vertical vibration damping devices can be switched between a ride comfort priority mode and an earthquake mode in which the generated force is greater than that of the ride comfort priority mode, and the earthquake mode is characterized in that the generated force on the extension side of the vertical vibration damping devices is smaller than the generated force on the compression side.

[0016] Furthermore, in the railway vehicle according to the present invention, the vertical vibration damping device preferably includes a vertical damper with adjustable damping force.

[0017] Furthermore, in the railway vehicle according to the present invention, it is preferable that the force generated on the extension side of the vertical vibration damping device in the earthquake mode is 80% or less of the force generated on the compression side of the vertical vibration damping device.

[0018] Furthermore, in the railway vehicle according to the present invention, the vertical vibration damping device preferably includes a vertical actuator arranged in parallel with the air spring.

[0019] Furthermore, in the railway vehicle according to the present invention, it is preferable that a lateral vibration damping device located between the vehicle body and the bogie is further provided, and that the lateral vibration damping device can switch between a ride comfort priority mode and an earthquake mode in which the generated force is greater than that of the ride comfort priority mode, in response to a signal from the earthquake detection means.

[0020] Furthermore, in the railway vehicle according to the present invention, the lateral vibration damping device preferably includes a lateral damper and / or a lateral actuator located between the vehicle body and the bogie, the damping force of which can be changed.

[0021] In addition, in the railway vehicle according to the present invention, it is preferable that the vibration damping force of the vertical vibration damping device with respect to the roll mode of the car body is increased by 20% or more in the earthquake mode than in the ride comfort priority mode.

[0022] In addition, in the railway vehicle according to the present invention, it is preferable to further include displacement limiting means that is connected to the car body and the bogie and limits the displacement of the car body and the bogie so as not to exceed at least one of the maximum elongation amount of the vertical vibration damping device and the maximum allowable elongation amount of the air spring.

[0023] In addition, in the railway vehicle according to the present invention, the displacement limiting means is a wire member connected to the car body and the bogie, and at least one end of the wire member is preferably attached to the car body or the bogie via an elastic member.

[0024] In addition, in the railway vehicle according to the present invention, it is preferable to further include a first acceleration sensor and a second acceleration sensor having a wider measurement range and / or higher vibration resistance than the first acceleration sensor, and to control the generated force of the vertical vibration damping device based on a signal from at least one of the first acceleration sensor and the second acceleration sensor.

[0025] In addition, in the railway vehicle according to the present invention, it is preferable to include failure detection means for detecting failures of the first acceleration sensor and the second acceleration sensor by comparing the outputs of the first acceleration sensor and the second acceleration sensor.

[0026] In addition, in the railway vehicle according to the present invention, it is preferable to include either a car body vertical acceleration sensor for detecting the vertical vibration of the car body or a car body vertical acceleration sensor and a vertical displacement sensor between the car body and the bogie.

[0027] In addition, in the railway vehicle according to the present invention, it is preferable to include either a car body lateral acceleration sensor for detecting the lateral vibration of the car body or a car body lateral acceleration sensor and a lateral displacement sensor between the car body and the bogie.

[0028] Furthermore, another railway vehicle according to the present invention is a railway vehicle having a car body and a bogie supporting the car body, comprising: a pair of air springs located between the car body and the bogie; a pair of vertical vibration damping devices arranged in parallel with the air springs and capable of changing the generated force; and an earthquake detection means for detecting earthquakes, wherein the vertical vibration damping devices can be switched between a ride comfort priority mode and an earthquake mode in which the generated force is greater than that of the ride comfort priority mode in response to a signal from the earthquake detection means, and further comprising displacement limiting means connected to the car body and the bogie, which limits the displacement of the car body and the bogie so as not to exceed at least one of the maximum extension amount of the vertical vibration damping devices and the maximum allowable extension amount of the air springs.

[0029] Furthermore, another railway vehicle according to the present invention is a railway vehicle having a car body and a bogie supporting the car body, comprising: a pair of air springs located between the car body and the bogie; a pair of vertical vibration damping devices arranged in parallel with the air springs and capable of changing the generated force; and an earthquake detection means for detecting earthquakes, wherein the vertical vibration damping devices can be switched between a ride comfort priority mode and an earthquake mode in response to a signal from the earthquake detection means, and further comprises a first acceleration sensor and a second acceleration sensor having a wider measurement range and / or higher vibration resistance than the first acceleration sensor, and is characterized in that the generated force of the vertical vibration damping devices is controlled based on a signal from at least one of the first acceleration sensor or the second acceleration sensor. [Effects of the Invention]

[0030] The present invention provides a railway vehicle that can provide a comfortable ride under normal conditions, suppress vehicle sway (especially body rolling vibration) and relative displacement between the body and the bogie that cause a decrease in wheel load during an earthquake, and further suppress the occurrence of large vertical displacements of the air springs that would cause air leakage from the air springs, thereby reducing the possibility of the railway vehicle derailing. [Brief explanation of the drawing]

[0031] [Figure 1] A schematic diagram showing an example of a railway vehicle according to the first embodiment of this disclosure. [Figure 2] A graph showing examples of damping force characteristics in a ride comfort priority mode and an earthquake mode for a vertical damper used in a railway vehicle according to the first embodiment of this disclosure, wherein (a) is a graph showing the case when only the damping coefficient is switched, and (b) is a graph showing the case when both the damping coefficient and the relief characteristics are switched. [Figure 3] A schematic diagram showing a modified example of a railway vehicle according to the first embodiment of this disclosure. [Figure 4] A schematic diagram showing an example of a railway vehicle according to the second embodiment of this disclosure. [Figure 5] A top view of a railway vehicle body showing an example of the arrangement of vertical vibration detection means for the vehicle body according to the second embodiment of this disclosure. [Figure 6] A schematic diagram showing a modified example of a railway vehicle according to the second embodiment of this disclosure. [Figure 7] A top view of a vehicle body showing an example of the arrangement of vertical vibration detection means and lateral vibration detection means for a modified railway vehicle according to the second embodiment of this disclosure. [Figure 8] A schematic diagram showing an example of a railway vehicle according to the third embodiment of this disclosure. [Figure 9] A schematic diagram showing a modified example of a railway vehicle according to the third embodiment of this disclosure. [Figure 10] A schematic diagram showing an example of a railway vehicle according to the fourth embodiment of this disclosure. [Figure 11] Figure 10 is an enlarged view of section A, where (a) shows an example using rubber and coil springs, and (b) shows an example using leaf springs. [Figure 12] This figure shows a modified example of a displacement limiting mechanism, where (a) shows an example using rubber or a coil spring, and (b) shows an example using a leaf spring. [Figure 13] A graph illustrating the operation of the displacement limiting mechanism. [Figure 14]A schematic diagram showing another example of a railway vehicle according to the fourth embodiment of this disclosure. [Figure 15] Diagram showing the vehicle dynamics model used in the simulation. [Figure 16] Graph showing the damping force characteristics of the lateral damper used in the simulation. [Figure 17] Graph showing the damping force characteristics of the vertical damper used in the simulation. [Figure 18] Graph showing the simulation results [Figure 19] Graph showing the simulation results [Modes for carrying out the invention]

[0032] The railway vehicles according to the embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are not intended to limit the invention as defined in the claims, and not all of the elements and combinations thereof described in each embodiment are necessarily essential to the solution of the present invention.

[0033] [First Embodiment] Figure 1 is a schematic diagram showing an example of a railway vehicle according to the first embodiment of this disclosure; Figure 2 is a graph showing examples of damping force characteristics in ride comfort priority mode and seismic mode of a vertical damper used in a railway vehicle according to the first embodiment of this disclosure, where (a) is a graph showing the case when only the damping coefficient is switched, and (b) is a graph showing the case when both the damping coefficient and the relief characteristics are switched; and Figure 3 is a schematic diagram showing a modified example of a railway vehicle according to the first embodiment of this disclosure.

[0034] The railway vehicle 1 according to the embodiment of this disclosure comprises a car body 2 and a bogie frame 3. The following description will focus on the case where the railway vehicle 1 according to the embodiment of this disclosure comprises a wheelset 6 consisting of a pair of left and right wheels 4 and an axle 5 connecting the pair of wheels 4, an axle box 7 that rotatably supports both ends of the wheelset 6, an axle spring 9 that supports the bogie frame 3 so as to be displaceable relative to the axle box 7, and an air spring 8 that supports the car body 2 so as to be displaceable relative to the bogie frame 3. However, the railway vehicle according to the embodiment of this disclosure is not limited to the illustrated form and only comprises a car body and a bogie frame. For example, it is also possible to have a maglev train or the like (e.g., a linear motor car) equipped with the railway vehicle, car body, and bogie frame according to the embodiment of this disclosure.

[0035] As an example of a railway vehicle vibration damping device according to the embodiment of this disclosure, the railway vehicle 1, as shown in Figure 1, comprises a car body 2 and bogies. The car body 2 is a structure for loading and transporting passengers, etc. The bogies are devices that support the car body 2 and run on it, and include a bogie located in front of the car body 2 (hereinafter referred to as the front bogie) and a bogie located behind the car body 2 (hereinafter referred to as the rear bogie). Each bogie comprises a wheelset 6 consisting of a pair of left and right wheels 4 and an axle 5 connecting the pair of left and right wheels 4, an axle box 7, a bogie frame 3, an air spring 8, etc. It also includes a lateral damper 25 that dampens lateral movement between the car body and the bogie.

[0036] The wheel 4 is a component that rolls and makes contact with the rail, and the axle 5 is a component that rotates integrally with the wheel 4. The axle box 7 is a component that rotatably supports both ends of the wheelset 6 via bearings (not shown), and is held in a predetermined position on the bogie frame 3 by an axle box support device such as an axle spring 9. The bogie frame 3 is the main component of the bogie and includes a bogie frame 3 that constitutes the front bogie and is located in front of the car body 2 (hereinafter referred to as the front bogie frame), and a bogie frame 3 that constitutes the rear bogie and is located behind the car body 2 (hereinafter referred to as the rear bogie frame). As an example, the bogie frame 3 is composed of left and right side beams and crossbeams connecting them. The bogie frame transmits longitudinal forces to the car body by a traction device (not shown).

[0037] The axle spring 9 connects the axle box 7 and the bogie frame 3, elastically supports vertical loads, and functions as a spring that mitigates shocks between them. Examples of axle springs include coil springs and cylindrical laminated rubber.

[0038] The air spring 8 connects the car body 2 and the bogie frame 3, supports the vertical load of the car body 2, and functions as a spring that reduces vibrations transmitted from the bogie frame 3 to the car body 2. Although it is known that vertical damping of railway vehicles is generated by a throttling (not shown) provided inside the air spring, in the railway vehicle 1 according to this embodiment, it is desirable to remove the throttling inside the air spring 8 in order to improve ride comfort.

[0039] Furthermore, a vertical vibration damping device 10 is provided between the car body 2 and the bogie frame 3, arranged in parallel with the air spring 8. In the railway vehicle 1 according to this embodiment, the vertical vibration damping device 10 is composed of a switchable vertical damper 11. The mounting seats for the switchable vertical damper 11 on the car body 2 and the bogie frame 3 are provided with the necessary strength considering the maximum damping force of the switchable vertical damper 11.

[0040] The switchable vertical damper 11 has the function of switching the characteristics of the force generated (damping force characteristics) with respect to the extension and contraction speed of the vertical vibration damping device 10. The damping force characteristics of the switchable vertical damper 11 are set to two types: a ride comfort priority mode mainly used during normal driving, and an earthquake mode with a greater damping force than the ride comfort priority mode. These are switched by a solenoid valve (not shown) provided in the switchable vertical damper 11. A suitable specific switching method is to switch the energization of the solenoid valve in response to a signal from an earthquake detection means described later, with the ride comfort priority mode being used when the solenoid valve is not energized and the earthquake mode being used when it is energized. In this specification, the damping force of the damper is defined as the force resisting the extension when the switchable vertical damper 11 is pulled, and the force resisting the compression when the switchable vertical damper 11 is compressed, and the damping force resisting this is defined as the compression (damping) force.

[0041] Furthermore, it is desirable that the damping force characteristics of the switchable vertical damper 11, specifically the ride comfort priority mode, be equivalent to the damping effect generated by the constriction of a conventional air spring. This makes it possible to achieve the same ride comfort as conventional vehicles in the ride comfort priority mode.

[0042] On the other hand, in earthquake mode, the damping characteristics are such that the damping force on the extension side is smaller than the damping force on the compression side, and two patterns are possible, as shown in Figure 2. In (a), the damping characteristics switch so that only the damping coefficient increases, and the relief pressure of the damper does not change, and in (b), the damping characteristics switch so that both the damping coefficient and the relief pressure increase. Of the damping characteristics of (a) and (b), (b) has a higher effect in reducing low-frequency vibrations, but because the maximum damping force of the damper increases by increasing the relief pressure, the diameter of the damper tends to increase, and the switchable vertical damper 11 tends to become larger. As a result, more installation space is required for the switchable vertical damper 11, and the strength of the damper support on the vehicle body 2 and bogie frame 3 needs to be increased.

[0043] As shown above, increasing both the damping coefficient and the maximum damping force, as in (b), results in a higher vibration reduction effect. However, if the maximum damping force is increased, the switchable vertical damper 11 and its mounting base will become larger, which may make it difficult to fit the switchable vertical damper 11 and its mounting base within the vehicle clearance. Therefore, appropriate selection is necessary. In addition, if a large damping force is generated on the extension side, the switchable vertical damper 11 may act to pull the bogie frame 3 vertically upward, which may lead to a decrease in wheel load. To suppress the possibility of derailment due to a decrease in wheel load, the damping force on the extension side should be set smaller than the damping force on the compression side. It is preferable that the damping force on the extension side be set to 80% or less of the damping force on the compression side, and more preferable that it be set to 50% or less.

[0044] Furthermore, the switchable vertical damper 11 is best configured as a biflow circuit.

[0045] Furthermore, as shown in Figure 1, the railway vehicle 1 according to this embodiment is equipped with an earthquake detection means and a switching device.

[0046] Any configuration can be used for earthquake detection means as long as it can detect the occurrence of an earthquake and transmit an earthquake detection signal to a switching device. For example, methods of earthquake detection include: (a) in the case of high-speed rail vehicles, an early earthquake detection system or similar activates during an earthquake, automatically stopping the power supply to the overhead lines and causing a blackout. A method of detecting this blackout is used; (b) an acceleration sensor is installed on the vehicle to determine that an earthquake has occurred when significant shaking occurs; and (c) the signaling system is improved so that earthquake detection signals from the aforementioned early earthquake detection system can be directly received on the vehicle. However, since (a) and (b) take time to detect an earthquake, (c), which can directly detect the occurrence of an earthquake, is the most desirable.

[0047] When the switching device receives an earthquake detection signal from the earthquake detection means, it quickly drives the solenoid valve of the switchable vertical damper 11 and switches the switchable vertical damper 11 to the earthquake mode, which has high damping characteristics.

[0048] In conventional railway vehicles, when subjected to large displacement excitation from the ground in the lateral direction during an earthquake, lateral vibration of the vehicle body and rolling motion occur. While this vibration is reduced to a certain magnitude by the damping effect of the lateral damper 25 between the vehicle body and the bogie, and the throttling installed inside the air spring, when the excitation force (or displacement) exceeds a certain magnitude, these parts alone are no longer sufficient to dampen the vibration, and the amplitude increases. As a result, the following phenomena occur.

[0049] The lateral movement stopper (not shown), which is installed between the car body 2 and the bogie frame 3 and limits the displacement between the car body and the bogie frame, normally has a gap of about 40 mm in the neutral position. However, when the roll vibration or lateral vibration of the car body 2 becomes significant, this gap is used up, the lateral movement stopper makes contact at a high speed, and a large reaction force is generated. Similarly, the upper and lower plates inside the air spring normally have a gap of about 40 mm in the neutral position. However, when the vertical and roll vibration of the car body 2 becomes significant, this gap is used up, the upper and lower plates make contact at a high speed (bottoming out of the air spring), and a large reaction force is generated.

[0050] In such situations, the reaction forces generated by the lateral movement stoppers and the upper and lower plates of the air springs act on the bogie in the roll direction or lateral direction, increasing the wheel load fluctuations. If this continues, the wheels may lift off the ground. Furthermore, if the vertical and roll vibrations of the vehicle body become significant, the deformation of the air springs can become too large, causing air leaks (punctures) in the air springs. As a countermeasure against such earthquakes, vibration suppression measures through improvements to the vehicle and structure are considered to be effective.

[0051] In contrast, in the railway vehicle 1 according to this embodiment, after the earthquake detection means detects the occurrence of an earthquake and the switching means receives the earthquake detection signal, the switchable vertical damper 11 is quickly switched to earthquake mode and given high damping characteristics. As a result, the vertical and roll motion of the vehicle body is suppressed by the switchable vertical damper 11 switched to earthquake mode, and the swaying of the vehicle body 2 (and the relative displacement between the vehicle body and the bogie) is reduced. As a result, it is expected that the occurrence of bottoming out of the air springs, contact with the lateral movement stoppers, and air leakage of the air springs 8 will be suppressed, reducing the likelihood of wheel load reduction and wheel lift-up, thereby reducing the possibility of derailment of the railway vehicle 1. Furthermore, since the damping force characteristics of the switchable vertical damper 11 are switched between earthquake occurrence and normal running, the damping force characteristics of the damper can be made more suitable for the conditions of earthquake occurrence and normal running, respectively.

[0052] Furthermore, in earthquake mode, the damping force on the extension side is set to be smaller than the damping force on the compression side, so the effect of the switchable vertical damper 11 pulling the bogie upward and reducing the wheel load can be suppressed. In the railway vehicle 1 according to this embodiment, since the damping force on the extension side of the switchable vertical damper 11 in earthquake mode is set to be smaller than the damping force on the compression side, although the effect of suppressing vertical and roll vibrations of the railway vehicle 1 is slightly reduced, the reduction in wheel load when the switchable vertical damper 11 is extended can be reduced. By these methods, the railway vehicle 1 according to this embodiment is expected to reduce the possibility of derailment of the railway vehicle 1 by making it less likely for the wheel load to decrease and the wheels 4 to lift off the ground.

[0053] Furthermore, as shown in Figure 3, the railway vehicle according to this embodiment may be equipped with a switchable lateral damper 21 as a lateral vibration damping device 20 instead of the lateral damper 25.

[0054] In this way, by providing a switchable lateral damper 21, when an earthquake is detected, both the switchable vertical damper 11 and the switchable lateral damper 21 can be switched to earthquake mode, thereby achieving an even higher vibration suppression effect (suppression of the possibility of derailment). This is because, when only the switchable vertical damper 11 is set to earthquake mode, it is effective in reducing vibrations in the vertical and roll directions of the vehicle body 2, but the damping in the lateral direction is the same as in a normal vehicle using a lateral damper, making it difficult to suppress the phenomenon of the lateral damper stopper hitting due to the lateral movement of the vehicle body 2. However, by setting both the switchable vertical damper 11 and the switchable lateral damper 21 to earthquake mode with high damping, the lateral movement of the vehicle body 2 can also be dampened, so the contact with the lateral damper can be effectively suppressed, and it is expected that the possibility of the vehicle derailing will be reduced.

[0055] [Second Embodiment] In the railway vehicle according to the first embodiment described above, the case in which a switchable vertical damper is used as the vertical vibration damping device was explained. The railway vehicle according to the second embodiment described next describes an embodiment of the vertical vibration damping device having a different configuration from the first embodiment. In addition, components that are the same as or similar to those in the first embodiment described above are denoted by the same reference numerals and their description is omitted.

[0056] Figure 4 is a schematic diagram showing an example of a railway vehicle according to the second embodiment of this disclosure; Figure 5 is a top view of the vehicle body showing an example of the arrangement of vertical vibration detection means for the vehicle body of a railway vehicle according to the second embodiment of this disclosure; Figure 6 is a schematic diagram showing a modified example of a railway vehicle according to the second embodiment of this disclosure; and Figure 7 is a top view of the vehicle body showing an example of the arrangement of vertical vibration detection means and lateral vibration detection means for the vehicle body of a modified example of a railway vehicle according to the second embodiment of this disclosure.

[0057] As shown in Figure 4, the railway vehicle 1a according to this embodiment includes a car body 2, a bogie that supports the car body 2 and runs on it, a wheelset 6 consisting of a pair of left and right wheels 4 and an axle 5 connecting the pair of left and right wheels 4, an axle box 7, a bogie frame 3, and air springs 8, etc. It also includes a lateral damper 25 that dampens lateral vibrations between the car body and the bogie.

[0058] Furthermore, a vertical vibration damping device 10 is provided between the car body 2 and the bogie frame 3, arranged in parallel with the air spring 8. In the railway vehicle 1a according to this embodiment, the vertical vibration damping device 10 is composed of a variable damping vertical damper 12. The mounting seats for the variable damping vertical damper 12 on the car body 2 and the bogie frame 3 are provided with the necessary strength considering the maximum damping force of the variable damping vertical damper 12.

[0059] The railway vehicle 1a according to this embodiment is equipped with an earthquake detection means and a control device that controls the damping force of the variable damping vertical damper 12. The method for detecting the occurrence of an earthquake is the same as that of the railway vehicle 1 according to the first embodiment described above, so a detailed explanation is omitted.

[0060] Furthermore, the railway vehicle 1a according to this embodiment is equipped with a vehicle body vibration detection means 30. The vehicle body vibration detection means 30 is installed on the vehicle body 2 and detects vibrations of the vehicle body 2. The vehicle body vibration detection means 30 outputs a vibration detection signal, such as a vertical acceleration signal, to the control device in accordance with the vibration of the vehicle body 2. At least two vehicle body vibration detection means 30 are required per vehicle body to be attached to the vehicle body 2.

[0061] There are no limitations on the mounting position of the vehicle body vibration detection means 30, but as shown in Figure 5(a), it is preferable to arrange a total of four vertical acceleration sensors 31, two each along the centerlines in the longitudinal and width directions of the vehicle body 2. Alternatively, as shown in Figure 5(b), vertical acceleration sensors 31 may be arranged near the four corners of the vehicle body 2, or as shown in Figure 5(c), three vertical acceleration sensors 31 may be arranged along the longitudinal centerline, with a roll gyro 31a placed adjacent to the central vertical acceleration sensor 31. By arranging the vehicle body vibration detection means 30 in this way, it becomes possible to detect vertical translation, pitch, and roll mode vibrations of the vehicle body 2. Furthermore, as shown in Figures 5(a) and (c), if acceleration sensors 31 are arranged both directly above the bogie and in the center of the vehicle body, it becomes possible to detect not only vertical translation, pitch, and roll mode vibrations of the vehicle body 2, but also vertical primary bending mode vibrations of the vehicle body 2 with the longitudinal center of the vehicle body 2 as the antinode of the vibration.

[0062] Furthermore, the vehicle body vibration detection means 30 is not limited to the vertical acceleration sensor 31 and roll gyro 31a provided on the vehicle body 2, but may also use a vertical displacement sensor installed between the vehicle body and the bogie. For example, a height adjustment valve is used to maintain a constant height of the air spring 8 by controlling the intake and exhaust of air from the air spring 8. Some of these height adjustment valves also have a function to output a vertical displacement signal, and this function can be used.

[0063] The variable damping vertical damper 12 has a hydraulic circuit, and preferably has, for example, a conventionally known biflow circuit. The damping force characteristics of this variable damping vertical damper 12 have damping force control valves for both the extension and compression strokes, and are configured to allow the damping force to be continuously and independently controlled on the extension and compression sides from minimum damping to maximum damping according to the magnitude of the command current supplied to the damping force control valve from the control device. In the control-off (power off) state, it functions as a vertical damper having damping force characteristics equivalent to a normal air spring with a throttling mechanism to obtain a damping effect. In this specification, the damping force of the damper is defined as the force resisting the extension side (damping force) when the variable damping vertical damper 12 is pulled, and the force resisting the compression side (damping force) when the variable damping vertical damper 12 is compressed.

[0064] Two possible configurations for the hydraulic circuit and damping force variable range of the variable damping vertical damper 12 during normal operation and during earthquakes are possible: (a) The damping force is controlled by the same hydraulic circuit and control valve during both normal operation and earthquakes. (b) A separate hydraulic circuit for use during earthquakes is built in, in addition to the damping force control circuit used during normal operation, and is switched on during earthquakes.

[0065] In case (a), the maximum value of the variable damping force range of the variable damping vertical damper 12 is set to the maximum damping force used during an earthquake, and during normal control, the control device can limit the damping force command value to a certain extent. In this way, the variable damping vertical damper 12 prevents the generation of excessive damping force that would impair ride comfort during normal control, while during an earthquake, a damping force greater than the normally used damping force can be used, making it easier to obtain a derailment prevention effect.

[0066] In case (b), a switching mechanism for the hydraulic circuit is required for normal operation and during earthquakes. Possible methods for this include (a) implementing a solenoid valve in the variable damping vertical damper 12 separately from the control valve, and switching the switching valve by driving it from the control device during an earthquake, or (b) devising the structure of the damping force control valve to supply a current larger than the normal command current to the control valve, thereby switching to a hydraulic circuit dedicated to earthquakes. In case (b), since a dedicated hydraulic circuit for use during earthquakes is configured, the damping force characteristics can be specialized for preventing derailment during earthquakes, but it is not possible to perform derailment prevention control by online control of the damping force during earthquakes (details will be described later). In case (b), the damping force characteristics of the variable damping vertical damper 12 for earthquakes are designed in advance so that the damping force on the extension side is smaller than the damping force on the compression side.

[0067] The control device, under normal conditions, receives acceleration signals from vehicle body vibration detection means 30, such as acceleration sensors 31 attached to the vehicle body 2. Based on these signals, it calculates the damping force command value necessary to suppress vertical, pitch, and roll vibrations of the vehicle body 2 in order to improve vertical ride comfort, and supplies a command current to the variable damping vertical damper 12 (ride comfort priority mode). Various conventionally known control laws can be used for the control law, but for example, the mode-specific Skyhook control law is preferable. In particular, by arranging the vehicle body vibration detection means 30 as shown in Figures 5(a) and 5(c), vibrations in the vertical translation, pitch, roll, and primary bending modes of the vehicle body can be controlled and reduced. In addition to the Skyhook control law, modern control theories (LQG control and H∞ optimal control) can also be used.

[0068] Furthermore, the railway vehicle 1a according to this embodiment has a function to receive an earthquake detection signal from an earthquake detection means. Upon receiving the detection signal, it stops the normal vibration control mode, which is the ride comfort priority mode, and commands the damping force control valve of the variable damping vertical damper 12 with an electric current to switch to the earthquake mode, which has high damping characteristics for use during earthquakes. In addition, if there is a dedicated hydraulic circuit and solenoid valve for earthquake response, the solenoid valve is driven to switch to the high damping characteristics for earthquakes.

[0069] In this embodiment, the railway vehicle 1a, configured as described above, normally controls the variable damping vertical motion damper 12 based on the vertical acceleration of the vehicle body received from the vertical acceleration sensor 31 attached to the vehicle body 2, thereby reducing the vertical and roll vibrations of the vehicle body 2 to improve ride comfort. When an earthquake detection signal is received from the earthquake detection means, the normal vibration control is stopped, and the variable damping vertical motion damper 12 is switched to an earthquake mode with high damping to suppress derailment during an earthquake. In this embodiment, during an earthquake, the vehicle body vibration detection means 30 is not used, and a predetermined constant command value is commanded from the control device to the variable damping vertical motion damper 12. Therefore, even if the vehicle body vibration detection means 30 malfunctions, the system can still switch to earthquake mode.

[0070] By operating in this manner, the variable damping vertical damper 12 is effectively utilized both under normal conditions and during earthquakes, contributing to improved vertical ride comfort under normal conditions and to suppressing derailment during earthquakes.

[0071] Furthermore, as shown in Figure 6, the railway vehicle according to this embodiment may also use a variable damping lateral damper 22, which is a lateral vibration damping device 20, as the lateral damper. In this case, by using the variable damping lateral damper 22 and providing high damping characteristics during an earthquake, it is possible to suppress vehicle sway and relative displacement between the vehicle body and the bogie, which cause a decrease in wheel load during large displacement excitations caused by earthquakes, thereby reducing the possibility of vehicle derailment. Note that the variable damping lateral damper 22 has a configuration and control method similar to the variable damping vertical damper 12 described above, except that it has generally the same high damping force characteristics on the extension and compression sides, so a detailed explanation is omitted.

[0072] As shown in Figure 7(a), the vehicle body vibration detection means 30 preferably has four vertical acceleration sensors 31 arranged in total, two each along the centerlines in the longitudinal and width directions of the vehicle body 2, with the left-right acceleration sensors 32 positioned close to the vertical acceleration sensors 31 along the longitudinal centerline. Alternatively, as shown in Figure 7(b), vertical acceleration sensors 31 may be arranged near the four corners of the vehicle body 2, and the left-right acceleration sensors 32 may be positioned along the longitudinal centerline. Or, as shown in Figure 7(c), three vertical acceleration sensors 31 may be arranged along the longitudinal centerline, a roll gyro 31a may be placed adjacent to the central vertical acceleration sensor 31, and the left-right acceleration sensors 32 may be placed close to the vertical acceleration sensors 31 along the longitudinal centerline. By arranging the vehicle body vibration detection means 30 in this way, it becomes possible to detect vertical translation, pitch, roll, left-right translation, and yaw mode vibrations of the vehicle body 2. Furthermore, as shown in Figures 7(a) and (c), by placing vertical acceleration sensors 31 both directly above the bogie and in the center of the car body, it is possible to detect not only vertical translational, pitch, and roll mode vibrations of the car body 2, but also vibrations of the car body 2's vertical primary bending mode, with the longitudinal center of the car body 2 as the antinode of the vibration.

[0073] In this modified version of the railway vehicle according to this embodiment, a vibration control system is configured using variable damping dampers not only in the vertical direction but also in the horizontal direction, contributing to improved ride comfort in both vertical and horizontal directions under normal conditions, and to suppress derailment during earthquakes. In this embodiment, a high vibration damping effect is achieved in both vertical and horizontal directions, so a greater improvement in ride comfort and a greater effect in suppressing derailment during earthquakes can be expected.

[0074] Thus, the railway vehicle according to this embodiment can obtain not only the effect of suppressing derailment during earthquakes as in the railway vehicle according to the first embodiment, but also an effect of improving ride comfort during normal conditions. Furthermore, by controlling and utilizing the variable damping vertical damper 12 and the variable damping horizontal damper 22 to the damping force characteristics required during normal conditions and earthquakes, it contributes to improving ride comfort even during normal conditions compared to conventional derailment prevention measures, thus offering superior cost-effectiveness.

[0075] In the control method described above, we explained the case where, in earthquake mode, the characteristics of the variable damping vertical damper 12 become fixed to high damping mode when an earthquake detection signal is received from the earthquake detection means. However, when an earthquake detection signal is received, the variable damping vertical damper 12 can also be controlled based on the signal from the vehicle body vibration detection means 30 to suppress the reduction in wheel load and reduce the possibility of vehicle derailment.

[0076] The vehicle body vibration detection means 30 preferably uses a vertical acceleration sensor 31 attached to the vehicle body 2, or a vertical acceleration sensor 31 and a roll gyro 31a. Based on the signal from the vertical acceleration sensor 31, mode-specific skyhook control can be applied to suppress vertical and roll vibrations of the vehicle body 2. For example, by using the same algorithm both under normal conditions and during earthquakes, and switching to increase the control gain for the roll mode, which has a particularly large impact on derailment, and decrease the control gain for other modes (e.g., pitching and primary bending modes) during earthquakes, the limited force that can be generated by the variable damping vertical motion damper 12 is preferentially applied to the vibration modes that have a large impact on derailment, thereby more effectively suppressing the possibility of derailment.

[0077] Furthermore, as a control algorithm during earthquakes, it is possible to use, for example, modern control theory (LQG control or H∞ control) to control the vehicle in a way that suppresses the decrease in wheel load. Specifically, a state estimator (observer or Kalman filter) based on a vehicle dynamics model (e.g., Figure 15) is used to estimate the vehicle's motion state from the output of the vehicle's vertical acceleration sensors, and the variable damping vertical damper 12 is controlled to suppress wheel load fluctuations using the optimal control law or the H∞ control law. For example, by including vehicle roll vibration in the evaluation function and increasing the evaluation weight for it, the roll vibration reduction effect can be increased, or by applying a low-frequency weight (0.5~2Hz) to further enhance the roll vibration reduction effect. In addition, by including wheel load fluctuations in the evaluation function, it is possible to apply control that suppresses wheel load fluctuations themselves.

[0078] Furthermore, as a means of detecting vertical vibration of the vehicle body, a vertical displacement sensor between the vehicle body and the bogie may be used in combination with the vertical acceleration sensor. In vehicles equipped with an air spring vehicle body tilting device, for example, a displacement sensor function may be attached to the height adjustment valve used to maintain a constant height of the vehicle body, and the output of that valve can be used. By estimating the state using the vertical displacement between the vehicle body and the bogie in combination, the motion state of each part of the vehicle can be estimated more accurately, and the control of vehicle vibration and wheel load reduction during earthquakes can be performed with greater precision.

[0079] As mentioned above, when performing suppression control against large displacement excitation during an earthquake, increasing the damping force on the extension side can have a significant impact on the reduction in wheel load in situations where the wheel load decreases due to large vehicle oscillations caused by the earthquake. Therefore, when controlling the variable damping vertical damper 12 during an earthquake, the impact on the reduction in wheel load can be reduced by making the damping force on the extension side of the variable damping vertical damper 12 lower than that on the compression side. There are three specific methods for doing this: (a) setting the control gain on the extension side to be smaller than the control gain on the compression side, (b) making the maximum damping command (limiter) on the extension side smaller than the maximum damping command (limiter) on the compression side, and (c) using a combination of (a) and (b). By doing so, when the damper extends, the damper will pull the bogie upward, making it less likely for the wheel load to decrease and the wheels to lift off the ground, thereby reducing the possibility of vehicle derailment.

[0080] Furthermore, the variable damping left-right damper 22 can be controlled in roughly the same way as the variable damping up-down damper 12 described above, except that the damping force characteristics and control gain of the damper are basically the same for the extension and compression sides.

[0081] [Third Embodiment] In the railway vehicle according to the second embodiment described above, the case in which a variable damping vertical damper is used as the vertical vibration damping device was explained. The railway vehicle according to the third embodiment described next describes an embodiment of the vertical vibration damping device having a different configuration from the first and second embodiments. In addition, components that are the same or similar as those in the first and second embodiments described above are denoted by the same reference numerals and their descriptions are omitted.

[0082] Figure 8 is a schematic diagram showing an example of a railway vehicle according to the third embodiment of this disclosure, and Figure 9 is a schematic diagram showing a modified example of a railway vehicle according to the third embodiment of this disclosure.

[0083] As shown in Figure 8, the railway vehicle 1b according to this embodiment includes a car body 2, a bogie that supports the car body 2 and runs on it, a wheelset 6 consisting of a pair of left and right wheels 4, an axle 5 connecting the pair of left and right wheels 4, an axle box 7, a bogie frame 3, an air spring 8, and the like.

[0084] Furthermore, a vertical vibration damping device 10 is provided between the car body 2 and the bogie frame 3, arranged in parallel with the air spring 8. In the railway vehicle 1b according to this embodiment, the vertical vibration damping device 10 is composed of a variable damping vertical damper 12. The mounting seats for the variable damping vertical damper 12 on the car body 2 and the bogie frame 3 are provided with the necessary strength considering the maximum damping force of the variable damping vertical damper 12.

[0085] Furthermore, it is equipped with a lateral vibration damping device 20 that dampens lateral vibrations of the car body 2 and the bogie frame 3, and is provided with a switchable lateral damper 21 and a lateral actuator 23, respectively.

[0086] The railway vehicle 1b according to this embodiment is equipped with an earthquake detection means and a control device that changes the damping characteristics of the variable damping vertical damper 12, the switchable horizontal damper 21, and the horizontal actuator 23 from a ride comfort priority mode to an earthquake mode when an earthquake is detected by the earthquake detection means. The method for detecting the occurrence of an earthquake is the same as that of the railway vehicle 1 according to the first embodiment described above, so a detailed explanation is omitted.

[0087] Furthermore, the railway vehicle 1b according to this embodiment is equipped with a vehicle body vibration detection means 30. The vehicle body vibration detection means 30 is provided on the vehicle body 2 and includes vertical vibration detection means and horizontal vibration detection means for detecting vibrations of the vehicle body 2. The vehicle body vibration detection means 30 outputs a vibration detection signal, such as an acceleration signal, to the control device in accordance with the vibration of the vehicle body 2. At least two vehicle body vibration detection means 30 are required per vehicle body. Specifically, the vehicle body vibration detection means 30 preferably uses vertical acceleration sensors 31, horizontal acceleration sensors 32, or roll gyro 31a provided on the vehicle body 2, but is not limited to these, and a vehicle body-to-bogie vertical displacement sensor and / or horizontal displacement sensor installed between the vehicle body and the bogie may also be used in combination. By using the vertical acceleration sensor 31, the vehicle body-to-bogie vertical displacement sensor and / or horizontal acceleration sensor 32, and the vehicle body-to-bogie horizontal displacement sensor, the control accuracy against wheel load loss can be improved.

[0088] The left-right actuator 23 can be of any type as long as it provides the required force generation, responsiveness of the generated force to the force command, and energy supply, but an electro-hydraulic actuator is preferably used, for example. Furthermore, it is even preferable that the electro-hydraulic actuator functions as a normal left-right damper when control from the control device is turned off, and if sufficient force generation is possible, the electro-hydraulic actuator can combine the functions of both the switchable left-right damper 21 and the left-right actuator 23, thereby eliminating the switchable left-right damper 21 and effectively reducing installation and maintenance costs.

[0089] Furthermore, in this embodiment, when the earthquake detection means detects an earthquake, the railway vehicle 1b activates the vertical vibration damping device 10 and the horizontal vibration damping device 20 in earthquake mode. The vertical vibration damping device 10 is a variable damping vertical damper 12, and in earthquake mode, similar to the railway vehicles 1 and 1a of the first and second embodiments, the damping force is greater than in the ride comfort priority mode, and the extension damping force is smaller than the compression damping force. The horizontal vibration damping device 20 is a switchable horizontal damper 21 and a horizontal actuator 23, and in earthquake mode, the generated force is greater than in the ride comfort priority mode.

[0090] Furthermore, as shown in Figure 9, the railway vehicle 1b according to this embodiment can also be configured to include a switchable vertical damper 11 and a vertical actuator 13 as vertical vibration damping devices 10, and a switchable horizontal damper 21 and a horizontal actuator 23 as horizontal vibration damping devices 20. Similar to the horizontal actuator 23, an electro-hydraulic actuator is preferably used for the vertical actuator 13. Moreover, it is even more preferable that the electro-hydraulic actuator functions as a normal vertical damper when control from the control device is turned off. If sufficient force can be generated, the electro-hydraulic actuator can combine the functions of both the switchable vertical damper 11 and the vertical actuator 13, thereby eliminating the switchable vertical damper 11 and reducing installation and maintenance costs.

[0091] As described above, in the railway vehicle 1b according to this embodiment, the vertical vibration damping device 10 is composed of a switchable vertical damper 11 and a vertical actuator 13, and / or the lateral vibration damping device 20 is composed of a switchable vertical actuator 21 and a lateral actuator 23. Under normal circumstances, it is switched to a ride comfort priority mode to improve ride comfort, and the switchable vertical damper 11 and the switchable lateral damper 21 have characteristics that do not hinder the vibration control of the vertical actuator 13 and / or the lateral actuator 23 (low damping is often appropriate), and vibration control is performed by the vertical actuator 13 and / or the lateral actuator 23. Furthermore, in the event of an earthquake, the switchable vertical damper 11 and / or the switchable lateral damper 21 are set to an earthquake mode with greater damping force than the ride comfort priority mode, and the thrust of the vertical actuator 13 and / or the lateral actuator 23 can be controlled according to the vertical and lateral vibrations detected by the vehicle body vibration detection means 30, thereby further enhancing the vibration damping effect. In the earthquake mode, similar to the railway vehicles 1 and 1a according to the first and second embodiments, the vertical vibration damping device 10 is controlled to generate a greater force than in the ride comfort priority mode, and the extension force is controlled to be smaller than the compression force. Similarly, the lateral vibration damping device 20 is set to generate a greater force in the earthquake mode than in the ride comfort priority mode, similar to the railway vehicles 1a' and 1b according to the second embodiment.

[0092] Here, in a vibration damping device having an actuator, the "extension-side force" of the vibration damping device is defined as the force that resists the pulling of the vibration damping device, that is, in the case of an actuator, the force that causes the actuator itself to contract. Similarly, the "compression-side force" of a vibration damping device is defined as the force that resists the compression of the vibration damping device, that is, in the case of an actuator, the force that causes the actuator itself to contract. Furthermore, "the extension-side force is smaller than the compression-side force" is defined as indicating one of the following conditions (including cases where multiple conditions apply): the "extension-side force" of the vibration damping device has a smaller feedback gain against vibration than the "compression-side force"; the "extension-side force" has a smaller maximum force as hardware of the vibration damping device than the "compression-side force"; the "extension-side force" has a smaller maximum force command value from the control device than the "compression-side force"; or the "extension-side force" has a smaller damping force of the switchable damper than the "compression-side force". As described above, the damping force of the damper is defined as follows: the force resisting the extension when the switchable vertical damper 11 is pulled is defined as the "extension (damping) force," and the direction of the force resisting the compression when the switchable vertical damper 11 is compressed is defined as the "compression (damping) force."

[0093] Furthermore, in this embodiment, the control method for the railway vehicle 1b during an earthquake involves switching or controlling both the damper and actuator to earthquake mode as described above. Alternatively, for example, during an earthquake, the actuator control may be turned off and only the damper may be set to high damping for vibration control, or the damper may be kept at normal damping while the actuator is set to earthquake priority control and / or thrust amplification (for use outside of rated specifications).

[0094] [Fourth Embodiment] In the railway vehicles according to the first to third embodiments described above, the cases in which a switchable vertical damper, a variable damping vertical damper, a vertical actuator, a switchable horizontal damper, a variable damping horizontal damper, and a horizontal actuator are used as vertical vibration damping devices and / or horizontal vibration damping devices, respectively, have been described. The fourth embodiment of the railway vehicle to be described next describes an embodiment having a structure that can be used in conjunction with the first to third embodiments. Note that components that are the same or similar as those in the first to third embodiments described above are denoted by the same reference numerals and their descriptions are omitted.

[0095] Figure 10 is a schematic diagram showing an example of a railway vehicle according to the fourth embodiment of this disclosure; Figure 11 is an enlarged view of part A in Figure 10, where (a) is a diagram showing an example using rubber and coil springs, and (b) is a diagram showing an example using leaf springs; Figure 12 is a diagram showing a modified example of the displacement limiting mechanism, where (a) is a diagram showing an example using rubber and coil springs, and (b) is a diagram showing an example using leaf springs; Figure 13 is a graph for explaining the operation of the displacement limiting mechanism; and Figure 14 is a schematic diagram showing another example of a railway vehicle according to the fourth embodiment of this disclosure.

[0096] As shown in Figure 10, the railway vehicle 1c according to this embodiment is equipped with a switchable vertical damper 11 as a vertical vibration damping device 10. Furthermore, it is equipped with an earthquake occurrence detection means and a switching device that switches the vertical vibration damping device 10 from ride comfort priority mode to earthquake mode when the earthquake occurrence detection means detects the occurrence of an earthquake. Note that, as with the third embodiment described above, a vertical actuator 13 may be provided in parallel with the switchable vertical damper 11, or a variable damping vertical damper 12 may be provided instead of the switchable vertical damper 11. When using the vertical actuator 13 or the variable damping vertical damper 12, in addition to the switching device, acceleration sensors and control devices (not shown) necessary for controlling these actuators and dampers are provided.

[0097] Furthermore, the railway vehicle 1c according to this embodiment is equipped with a displacement limiting means 40 between the car body 2 and the bogie frame 3. The displacement limiting means 40 is a member that limits large displacements in the extension direction between the car body 2 and the bogie, and has the function of preventing damage to the vertical vibration damping device 10 and the air spring 8.

[0098] Specifically, as shown in Figure 11(a), the system includes a wire member 41 connected to the vehicle body 2 and the bogie frame 3, and at least one end of the wire member 41 is equipped with, for example, a wire receiver 43 attached to the bogie frame 3, an elastic member receiver 45 attached to the end of the wire member 41 via a wire fastening member 44, and an elastic member 42 positioned between the wire receiver 43 and the elastic member receiver 45. The elastic member 42 can be any material as long as it has a predetermined elasticity, but for example, rubber or a coil spring is preferably used.

[0099] Furthermore, the wire member 41 limits the displacement between the vehicle body 2 and the bogie so as not to exceed the maximum extension of the vertical vibration damping device 10 and the air spring 8, and the length of the wire member 41 is smaller than the maximum extension mentioned above.

[0100] Furthermore, the displacement limiting means 40 is not limited to having an elastic member 42, but may also be composed of, for example, a leaf spring receiver 47 erected on the trolley frame 3 and a leaf spring 46 attached to the leaf spring receiver 47 to which a wire member 41 is attached, as shown in Figure 11(b).

[0101] In this way, by attaching the wire member 41, when the distance between the car body and the bogie shifts significantly, the tensile force of the wire gradually increases, making it possible to suppress the sudden application of enormous forces to the car body, bogie, and wire.

[0102] Furthermore, the displacement limiting means 40 preferably includes a displacement limiting mechanism as shown in Figure 12. Specifically, as shown in Figure 12(a), an elastic member displacement limiting stopper 48 having a smaller height dimension than the elastic member 42 can be attached between the wire receiver 43 and the elastic member receiver 45, or as shown in Figure 12(b), a leaf spring displacement limiting stopper 49 can be attached separately from the leaf spring receiver 47, and the tip of the leaf spring displacement limiting stopper 49 can be bent upwards from the leaf spring 46 to form a predetermined gap between the leaf spring 46 and the tip of the leaf spring displacement limiting stopper 49.

[0103] As shown in Figure 13, by providing a displacement limiting mechanism, the deformation region of the elastic member 42 and the leaf spring 46 can be determined, preventing damage to the elastic member 42 and the leaf spring 46 and defining the effective range of the wire member 41.

[0104] In the above embodiment, the displacement limiting means 40 was described in the case where it includes a wire receiver 43 and an elastic member 42, but it is also possible to give the wire member 41 itself elastic properties and omit the elastic member 42 of the wire receiver 43. By omitting these components and giving the wire member 41 itself elastic properties, the configuration can be simplified, but care must be taken because the desired effect cannot be obtained unless the elastic properties of the wire member 41 are strictly selected and controlled.

[0105] Furthermore, in the railway vehicle according to this embodiment, as shown in Figure 14, it is preferable that the vertical acceleration sensor 31 constituting the vehicle body vibration detection means 30 includes a first acceleration sensor 33 and a second acceleration sensor 34 that has a wider measurement range and / or higher vibration resistance than the first acceleration sensor 33. The vehicle body vibration detection means 30 detects vibrations in the vertical and / or horizontal directions and transmits signals to the control device, which controls the force generated by the vertical vibration damping device 10 and the horizontal vibration damping device 20 based on these signals. In this case, the first acceleration sensor 33, which has high resolution, is usually used, but the second acceleration sensor 34 may be used if necessary. Furthermore, since the second acceleration sensor 34 has a wider measurement range and / or higher vibration resistance than the first acceleration sensor 33, even if the vehicle body vibrates greatly due to large displacement excitation during an earthquake, the second acceleration sensor 34 can measure acceleration without over-rangeping. Even if components between the vehicle body and the bogie are impacted due to large displacement excitation, the second acceleration sensor 34 is less likely to malfunction, thereby improving the reliability of vibration control during earthquakes.

[0106] Furthermore, it is preferable that the railway vehicle 1c' according to this embodiment is equipped with fault detection means that compares the outputs of the first acceleration sensor 33 and the second acceleration sensor 34 to detect a malfunction in the first acceleration sensor 33 and the second acceleration sensor 34.

[0107] Next, the effects of the railway vehicles according to the first to fourth embodiments will be explained with reference to Figures 15 to 20. Figure 15 is a diagram showing the dynamic model of the vehicle used in the simulation, Figure 16 is a graph showing the damping force of the lateral damper used in the simulation, Figure 17 is a graph showing the damping force of the vertical damper used in the simulation, and Figures 18 and 19 are graphs showing the simulation results.

[0108] The simulation was performed using the half-car railway vehicle model shown in Figure 15 (a car body with one bogie and half the mass of a full car body) under the following conditions.

[0109] Both the bogie and the car body should be designed to accommodate vertical translation, horizontal translation, and roll motion. • Wheel-rail dynamics are not considered. The wheels and rails are in contact in the vertical direction, and a normal force acts upon them. In the lateral direction, the wheels are constrained to the rails and are subjected to forced displacement. • Wheel load fluctuations (decrease in wheel load) are evaluated using the normal force acting from the rails. The simulation is terminated when the normal force from the right or left rail becomes nearly zero. The mass and dimensions of the car body and bogies were set to specifications equivalent to those of Shinkansen trains.

[0110] The lateral and vertical dampers to be considered are as follows: [Left / Right Damper] As shown in Figure 16, the following two methods were used. In both cases, the damping force characteristics on the extension and compression sides differed only in direction, and their magnitudes were the same. The distance between the left and right movement stoppers was set to ±40 mm. (a) Characteristics that simulate a conventionally known lateral damper that is effective during earthquakes (per bogie, damping coefficient of 60kN / (m / s) in the low-speed range, higher in the range where the piston speed is faster than 0.2m / s, with a maximum damping force of 40kN). (b) High-damping lateral damper (damping coefficient 300kN / (m / s), maximum damping force 40kN).

[0111] [Up / Down Damper] As shown in Figure 17, four damping characteristics were used from among normal damping, high damping, and high damping only on the compression side. The height of the air spring in the neutral position (distance between the top and bottom plates) was set to 40 mm. (a) A conventional damping damper with damping characteristics nearly equivalent to a normal air spring, which has a damping effect due to the restriction (each unit has 30kN / (m / s) on both the extension and compression sides, and a maximum damping force of 10kN). (b) A high-damping damper with a damping coefficient (120kN / (m / s)) that is four times that of the damping in (a) above, both on the extension and compression sides, and a maximum damping force that is the same as in (a) (10kN). (c) Same as (b) above, except that the maximum damping force is twice that of (b) (20kN), a high-damping damper. (d) A high-damping damper having characteristics (a) on the extension side and (c) on the compression side.

[0112] Comparative Example 1 shows the results of simulations performed using a combination of a left-right damper (a) and a right-down damper (a), Comparative Example 2 shows the results of simulations performed using a combination of a left-right damper (a) and a right-down damper (b), Comparative Example 3 shows the results of simulations performed using a combination of a left-right damper (a) and a right-down damper (c), Comparative Example 4 shows the results of simulations performed using a combination of a left-right damper (b) and a right-down damper (c), Example 1 shows the results of simulations performed using a combination of a left-right damper (a) and a right-down damper (d), and Example 2 shows the results of simulations performed using a combination of a left-right damper (b) and a right-down damper (d).

[0113] In this simulation, the half-body model shown in Figure 15 was excited on the track side with left and right sinusoidal waves of 0.5 to 1.5 Hz, and the excitation amplitude at which the wheel load of either the right or left wheel became zero was determined. A zero wheel load was defined as when the normal force acting on the wheel from the rail was zero, as shown in Figure 15.

[0114] Figure 18 shows the minimum lateral excitation displacement at which the wheel load becomes zero for each lateral excitation frequency, for Comparative Examples 1 to 3 and Example 1. Compared to the case using a conventional lateral damper with normal characteristics and a vertical damper with normal characteristics, as in Comparative Example 1, when a high-damping vertical damper (maximum damping force 10kN) is used, as in Comparative Example 2, the lateral excitation displacement at which the wheel load becomes zero increases below 0.8Hz, but conversely decreases at frequencies above 0.9Hz. This trend becomes even more pronounced in Comparative Example 3 (maximum damping force 20kN), where the maximum damping force of the vertical damper is further increased. Below 0.9Hz, the lateral excitation displacement at which the wheel load becomes zero can be increased, but conversely decreases at frequencies above that.

[0115] In contrast, in Example 1, in order to suppress the reduction in wheel load, a damper was applied in which the damping force on the extension side of the vertical damper was set to normal damping, and only the compression side was set to high damping (maximum damping force of 20kN). As a result, compared to the case where both the extension and compression sides were set to high damping (Comparative Examples 2 and 3), it was possible to increase the lateral excitation displacement at which the wheel load becomes zero at frequencies of 0.7Hz or higher. Compared to Comparative Example 1 (using the characteristics of a conventionally used lateral damper and a vertical damper with normal characteristics), the lateral displacement at which the wheel load becomes zero in the frequency band of 0.9Hz or lower was increased, while the lateral displacement at which the wheel load becomes zero in the frequency band of 1Hz or higher was only slightly reduced.

[0116] This result can be explained as follows: When the vertical damper is set to high damping on both the extension and compression sides, the occurrence of bottoming out of the air spring is reduced, but because no measures are taken to reduce vibration in the lateral direction, the lateral displacement of the vehicle body remains the same or slightly increases, and the contact with the lateral movement stopper may become slightly stronger. In addition, the increased damping force of the vertical damper strengthens the effect of the vertical damper in pulling up the bogie. As in Example 1, when the vertical damper is set to high damping only on the compression side, the latter factor (the effect of the vertical damper in pulling up the bogie) is reduced, which is thought to make it less likely for the wheel load to be lost.

[0117] Comparative Example 4 and Example 2 were designed with high damping on the lateral motion dampers to suppress this phenomenon and prevent the wheel load from becoming zero with respect to lateral excitation. Figure 19 shows the results of calculating the minimum lateral excitation displacement at which the wheel load becomes zero for each lateral excitation frequency for Comparative Examples 1, 3, 4 and Example 2. In Comparative Example 4, where both the lateral motion dampers and the vertical motion dampers were highly damped, the excitation displacement at which the wheel load became zero at frequencies below 1 Hz was larger than in Comparative Example 1, compared to Comparative Examples 1 and 3, where the lateral motion dampers were not highly damped. Furthermore, at frequencies above 1 Hz, the results were the same as in Comparative Example 1, and the excitation displacement at which the wheel load became zero was no longer smaller than in Comparative Example 1.

[0118] In Example 2, where the lateral damper was set to high damping and the vertical damper was set to high damping only on the compression side and normal damping on the extension side, the lateral excitation displacement at which the wheel load became zero was larger at all frequencies compared to Comparative Example 1. Also, compared to Comparative Example 4, the lateral excitation displacement at which the wheel load became zero was larger in the frequency band of 0.8 Hz and above. However, at frequencies lower than 0.8 Hz, Comparative Example 4 showed a larger lateral excitation displacement at which the wheel load became zero. Whether Comparative Example 4 or Example 2 is preferable depends on the assumed seismic waves, vehicle specifications, and the characteristics of the ground structure, so the characteristics of the vertical damper and lateral damper should be appropriately selected by referring to these factors. However, from the perspective of preventing vehicle derailment, it is considered desirable to have a smaller reduction in wheel load for lateral excitation around 1 Hz, so in general, Example 2 is considered to be more advantageous in suppressing the possibility of derailment during an earthquake. [Explanation of symbols]

[0119] 1,1a,1b,1c,1d Railway vehicle, 2 Car body, 3 Bogie frame, 4 Wheel, 5 Axle, 6 Wheelset, 7 Axle box, 8 Air spring, 9 Primary spring, 10 Vertical vibration damping device, 11 Switchable vertical damper, 12 Variable damping vertical damper, 13 Vertical actuator, 20 Lateral vibration damping device, 21 Switchable left-right damper, 22 Variable damping left-right damper, 23 Left-right actuator, 25 Left-right damper, 30 Car body vibration detection means, 31 Vertical acceleration sensor, 32 Left-right acceleration sensor, 33 First acceleration sensor, 34 Second acceleration sensor, 40 Displacement limiting means, 41 Wire member, 42 Elastic member, 43 Wire receiver, 44 Wire fastening member, 45 Elastic member support, 46 leaf spring, 47 leaf spring support, 48 elastic member displacement limiting stopper, 49 leaf spring displacement limiting stopper.

Claims

1. A railway vehicle having a car body and a bogie that supports the car body, A pair of air springs located between the vehicle body and the bogie, A pair of vertical vibration damping devices are arranged in parallel with the aforementioned air spring, and the generated force can be changed. It comprises an earthquake detection means for detecting earthquakes, The vertical vibration damping device can switch between a ride comfort priority mode and an earthquake mode in which the generated force is greater than that of the ride comfort priority mode, in response to a signal from the earthquake detection means. The aforementioned earthquake mode is characterized in that the force generated on the extension side of the vertical vibration damping device is smaller than the force generated on the compression side.

2. The railway vehicle according to claim 1, characterized in that the vertical vibration damping device includes a vertical damper with adjustable damping force.

3. The railway vehicle according to claim 1, characterized in that the force generated on the extension side of the vertical damping device in the earthquake mode is 80% or less of the force generated on the compression side of the vertical damping device.

4. The railway vehicle according to claim 1 or 2, characterized in that the vertical vibration damping device includes a vertical actuator arranged in parallel with the air spring.

5. The vehicle body and the bogie are further equipped with a lateral vibration damping device, The railway vehicle according to claim 1, wherein the lateral vibration damping device is capable of switching between a ride comfort priority mode and an earthquake mode in which the generated force is greater than that of the ride comfort priority mode, in response to a signal from the earthquake detection means.

6. The railway vehicle according to claim 5, characterized in that the lateral vibration damping device includes a lateral damper and / or a lateral actuator located between the vehicle body and the bogie, with adjustable damping force.

7. The railway vehicle according to any one of claims 1 to 6, characterized in that the damping force by the vertical damping device with respect to the roll mode of the vehicle body is 20% or more greater in the earthquake mode than in the ride comfort priority mode.

8. The railway vehicle according to claim 1, further comprising displacement limiting means connected to the vehicle body and the bogie, which limits the displacement of the vehicle body and the bogie so as not to exceed at least one of the maximum extension of the vertical vibration damping device and the maximum allowable extension of the air spring.

9. The displacement limiting means is a wire member connected to the vehicle body and the bogie, The railway vehicle according to claim 8, characterized in that at least one end of the wire member is attached to the vehicle body or the bogie via an elastic member.

10. The system further comprises a first acceleration sensor and a second acceleration sensor having a wider measurement range and / or higher vibration resistance than the first acceleration sensor. The railway vehicle according to claim 1, characterized in that the force generated by the vertical vibration damping device is controlled based on a signal from at least one of the first acceleration sensor or the second acceleration sensor.

11. The system further comprises a first acceleration sensor and a second acceleration sensor having a wider measurement range and / or higher vibration resistance than the first acceleration sensor. The railway vehicle according to claim 5 or 6, characterized in that the force generated by the lateral vibration damping device is controlled based on a signal from at least one of the first acceleration sensor or the second acceleration sensor.

12. The railway vehicle according to claim 10, further comprising fault detection means for detecting a failure of the first acceleration sensor and the second acceleration sensor by comparing the outputs of the first acceleration sensor and the second acceleration sensor.

13. The railway vehicle according to claim 2 or 4, characterized in that it comprises either a vehicle body vertical acceleration sensor for detecting vertical vibration of the vehicle body, or a vehicle body vertical acceleration sensor and a vehicle body-to-bogie vertical displacement sensor.

14. The railway vehicle according to claim 5 or 6, characterized in that it comprises either a vehicle body lateral acceleration sensor for detecting lateral vibration of the vehicle body, or a vehicle body lateral acceleration sensor and a vehicle body-to-bogie lateral displacement sensor.

15. A railway vehicle having a car body and a bogie that supports the car body, A pair of air springs located between the vehicle body and the bogie, A pair of vertical vibration damping devices are arranged in parallel with the aforementioned air spring, and the generated force can be changed. It comprises an earthquake detection means for detecting earthquakes, The vertical vibration damping device can switch between a ride comfort priority mode and an earthquake mode where the generated force is greater than that of the ride comfort priority mode, in response to a signal from the earthquake detection means. A railway vehicle further comprising displacement limiting means connected to the vehicle body and the bogie, which limits the displacement of the vehicle body and the bogie so as not to exceed at least one of the maximum extension of the vertical vibration damping device and the maximum allowable extension of the air spring.

16. A railway vehicle having a car body and a bogie that supports the car body, A pair of air springs located between the vehicle body and the bogie, A pair of vertical vibration damping devices are arranged in parallel with the aforementioned air spring, and the generated force can be changed. It comprises an earthquake detection means for detecting earthquakes, The vertical vibration damping device can switch between a ride comfort priority mode and an earthquake mode where the generated force is greater than that of the ride comfort priority mode, in response to a signal from the earthquake detection means. The system further comprises a first acceleration sensor and a second acceleration sensor having a wider measurement range and / or higher vibration resistance than the first acceleration sensor. A railway vehicle characterized by controlling the force generated by the vertical vibration damping device based on a signal from at least one of the first acceleration sensor or the second acceleration sensor.

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