Brake device

Abstract

Provided is a brake device for a railway vehicle, the brake device being capable of exerting braking force even if torque transmitted from an electric motor is lost. A brake device (100) comprises an arm (10) that has a fulcrum, an electric motor (20) that drives and rotates one end of the arm, a biasing member (51) that is disposed at the other end of the arm and pushes and rotates the arm when an energy storage state is released, a holding mechanism (60) that holds or releases the energy storage state of the biasing member in accordance with an energizing state, and a friction material (70) that is engaged between the biasing member and the fulcrum of the arm.

Description

Brake device

[0001] The present disclosure relates to a brake device for railway vehicles.

[0002] Railway vehicles are equipped with a mechanical brake device that generates braking force by pressing a friction material against a rotating body that rotates as the vehicle travels, converting kinetic energy into thermal energy.

[0003] Mechanical brake devices include, for example, electric brake devices that obtain braking force by pressing a friction material against a rotating body by reciprocating the output shaft of a rotary-linear motion conversion mechanism through the rotation of an electric motor.

[0004] As an example of an electric brake device, there is known one that exerts braking force as follows: a screw shaft, to which rotation of an electric motor is transmitted via a speed reduction mechanism, swings one end of an arm in a direction away from the rotating body, and moves the friction material engaged with the other end of the arm in a direction approaching the rotating body to press it against the rotating body. (Patent Document 1)

[0005] In this configuration, the arm functions as a lever mechanism that boosts the output torque of the electric motor and transmits it to the action point, where the point at which the link mechanism engages with the arm is the force point, and the point at which the friction material engages with the arm on the opposite side of the force point relative to the fulcrum of the arm and close to the fulcrum is the action point.

[0006] Japanese Patent Laid-Open No. 03-082667

[0007] In the railway vehicle brake device disclosed in Patent Document 1, the movement of the friction material engaged with the arm and the resulting generation of braking force depend solely on the torque of the electric motor applied to the other end of the arm via the lever mechanism. For this reason, when the electric motor becomes inoperable for any reason, there is a risk that the torque acting on the force point of the arm will be lost and the braking force will be lost.

[0008] The present disclosure has been made in view of the above problems, and an object thereof is to provide a brake device for railway vehicles that can exert braking force even if torque transmitted from the electric motor that drives the arm is lost.

[0009] To solve the above problems, the railway vehicle brake device according to this disclosure comprises an arm having a pivot point, an electric motor that drives and rotates one end of the arm, a biasing member disposed at the other end of the arm that pushes and rotates the arm when the stored energy state is released, a holding mechanism that maintains or releases the stored energy state of the biasing member according to the energization state, and a friction material engaged between the pivot point of the arm and the biasing member.

[0010] The braking device of this disclosure makes it possible to exert braking force even when the torque transmitted from the electric motor is lost.

[0011] Figure 1 schematically shows the configuration of the brake device according to the embodiment. Figure 1 shows the state in which the electric motor exerts braking force. Figure 1 shows the state in which the biasing unit exerts braking force.

[0012] A power conversion device according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. In the following description, multiple components of the same type will be indicated by subscripted reference numerals, but the subscript may be omitted as appropriate when describing them without distinguishing between them.

[0013] Figure 1 shows an example of the configuration of a brake device 100 mounted on a railway vehicle that decelerates by mechanical braking force according to an embodiment, and shows the state of the brake device 100 when it is not operating (also called non-braking or non-stopping). Figure 2 shows the state when the electric motor provided in the brake device 100 is driven, causing the friction material to come into contact with the material to be friction-treated (also called braking or stopping).

[0014] The braking device 100 consists of an arm 10, an electric motor 20, a reduction mechanism 30, a rotary-to-linear motion conversion mechanism 40, a biasing unit 50, a holding mechanism 60, and friction material 70, and is housed in a case (not shown) and fixed to the bogie frame of the vehicle.

[0015] The arm 10 has a pivot point 10f, which is rotatably supported by a case (not shown). The output end of the rotation-to-linear motion conversion mechanism 40 engages with point 10a at one end of the arm 10, and the pressing portion 52 of the biasing portion 50 abuts against point 10b at the other end. The base of the friction material 70 is engaged with point 10s between the pivot point 10f and the biasing portion 50 of the arm 10, that is, between the pivot point 10f and point 10b. In the above configuration, points 10a and 10b are the points of force application, and point 10s is the point of action.

[0016] The electric motor 20 is an AC motor driven by three-phase AC power, and the direction of rotation, speed, torque, etc. of the rotor shaft are controlled by a brake control device (not shown).

[0017] The reduction gear mechanism 30 is a gear mechanism having an input shaft and an output shaft, with the input shaft coupled to the rotor shaft of the electric motor 20. The reduction gear mechanism 30 reduces the driving force of the electric motor 20 applied to the input shaft, increases the torque, and outputs it from the output shaft.

[0018] The rotary-to-linear motion conversion mechanism 40 is a ball screw, with one end of its rotatable screw shaft connected to the output shaft of the reduction mechanism 30 as the input end. The rotary-to-linear motion conversion mechanism 40 converts the rotational motion driving force transmitted from the reduction mechanism 30 to the screw shaft into linear motion driving force at the output end engaged with a nut. When the direction of the rotational motion input to the rotary-to-linear motion conversion mechanism 40 is switched, the direction of the linear motion at the output end is also switched. The output end of the rotary-to-linear motion conversion mechanism 40 engages with point 10a on the arm 10 and transmits the driving force to the arm 10.

[0019] The friction material 70 is fixed via its base to the point of application 10s between the pivot point 10f of the arm 10 and the biasing part 50. As the arm 10 rotates around the pivot point 10f, it moves closer to or further away from the material to be frictioned 90, which is a rotating body such as a wheel. The frictional force generated when the friction material 70 comes into contact with the rotating material to be frictioned 90 converts the kinetic energy of the material to be frictioned 90 into thermal energy.

[0020] As shown in Figure 2, the driving force of the electric motor 20 is transmitted to the arm 10, and as the arm 10 rotates, the friction material 70 is pressed against the material to be frictioned 90.

[0021] When the electric motor 20 rotates in the forward direction from a state where the friction material 70 is separated from the material being friction-treated 90, point 10a on the arm 10 is pulled toward the rotation-to-linear motion conversion mechanism 40 via the reduction mechanism 30 and the rotation-to-linear motion conversion mechanism 40. When point 10a is pulled, the arm 10 rotates around the pivot point 10f, and the friction material 70 moves toward the material being friction-treated 90. When the friction material 70 is pressed against the rotating material being friction-treated 90, a frictional force is generated in proportion to the pressing force, and the rotational speed of the material being friction-treated 90 decreases.

[0022] Conversely, when the electric motor 20 rotates in the opposite direction from a state in which the friction material 70 is in contact with the material being frictioned 90, point 10a on the arm 10 is pushed away from the rotation-to-linear motion conversion mechanism 40 via the reduction mechanism 30 and the rotation-to-linear motion conversion mechanism 40. When point 10a is pushed, the arm 10 rotates around the pivot point 10f, and the friction material 70 moves away from the material being frictioned 90. When the friction material 70 moves away from the material being frictioned 90, the frictional force exerted by the friction material 70 disappears, and the material being frictioned 90 becomes freely rotatable.

[0023] Next, with reference to Figure 3, the biasing unit 50 and the holding mechanism 60 provided in the brake device 100 according to the embodiment will be explained based on the case in which the biasing unit 50 drives the arm 10, causing the friction material to come into contact with the material to be frictioned and exert braking force.

[0024] The biasing section 50 has a biasing member 51 which is a coil spring with one end fixed, and a pressing section 52 which is connected to the other end of the biasing member 51. The biasing section 50 is arranged so that when the stored energy state of the biasing member 51 is released, the pressing section 52 presses point 10b on the arm, causing the arm 10 to rotate. The biasing member 51 is held by the holding mechanism 60 in a compressed state with stored energy that is shorter than its natural length.

[0025] The holding mechanism 60 is an electromagnetic clutch attached to the biasing unit 50, and holds or releases the stored energy state of the biasing unit 50 depending on the energized state. That is, it holds the stored energy state of the biasing unit 50 when energized and releases the stored energy state when not energized. The holding mechanism 60 releases the held state of the biasing unit 50 when there is a command from a brake control device (not shown) or when the power supply to the holding mechanism 60 is cut off.

[0026] When the holding mechanism 60 releases the stored energy from the biasing part 50, the biasing member 51 attempts to return to its natural length and exerts a biasing force. At this time, the pressing part 52 presses point 10b on the arm 10, causing the arm 10 to rotate around the pivot point 10f, and the friction material 70 moves toward the material to be frictioned 90. When the friction material 70 is pressed against the rotating material to be frictioned 90, a braking force is generated in proportion to the pressing force, and the rotational speed of the material to be frictioned 90 decreases. Also, when the friction material 70 is pressed against a stationary material to be frictioned 90, the stationary state of the material to be frictioned 90 is maintained.

[0027] In the above configuration, the distance between the fulcrum 10f and point 10b is larger than the distance between the fulcrum 10f and point 10s where the base of the friction material 70 engages. Therefore, point 10s where the base of the friction material 70 engages becomes the point of application of force, and point 10b becomes the point of effort. As a result, the biasing force of the biasing part 50 is amplified and transmitted to the friction material 70.

[0028] For example, if the power supply to the electric motor 20 and the holding mechanism 60 is interrupted, and the biasing unit 50 is pressing point 10b on the arm 10, causing the friction material 70 to contact the material to be frictioned 90, then when the power supply is restored, rotating the electric motor 20 in the reverse direction causes the arm 10 to rotate around the pivot point 10f, and the friction material 70 moves away from the material to be frictioned 90. At this time, the pressing unit 52 is pressed against point 10b on the arm 10, causing the biasing member 51 to be compressed and enter an energized state. By further energizing the holding member 60, the energized state of the biasing member 51 can be maintained.

[0029] With the above configuration, separate points on a single arm 10 can be driven by two power sources, the electric motor 20 and the biasing unit 50, respectively, thus providing a brake device 100 with increased redundancy in a simple configuration. For example, if a malfunction occurs in the electric motor 20, power booster 30, rotary-to-linear conversion mechanism 40, or the circuit supplying power to the electric motor 20, causing the torque of the electric motor 20 to be lost and preventing the arm 10 from being driven, the biasing force of the biasing unit 50 can be used to drive the arm 10 and activate the brake device 100.

[0030] Furthermore, the configuration maintains the stored energy state of the biasing unit 50 when the holding mechanism 60 is energized and releases the stored energy state when it is de-energized. This allows the biasing unit 50 to operate not only when the power supply is cut off and power cannot be supplied to the electric motor 20, but also when the power supply is cut off and power cannot be supplied to the electric motor 20. For this reason, for example, even if the power to the vehicle is turned off when the vehicle is stopped (stored) for a long time at a station or depot, the braking device 100 can exert braking force due to the biasing force of the biasing unit 50, thus maintaining the vehicle's stopped state. In addition, even in the event of a power outage in the power lines supplying power to the vehicle or a failure of the generator mounted on the vehicle, the vehicle can be safely stopped or maintained in a stopped state while in motion.

[0031] In this disclosure, the energy storage state of the biasing section 50 is defined as the state in which the biasing member 51 is compressed to a length shorter than its natural length, but is not limited to this state. It includes both the state in which the biasing member 51 is stretched to a length longer than its natural length.

[0032] The coil spring of the biasing member 51 has an elastic force large enough to generate a braking force that suppresses the rolling (rotation) of the railway vehicle by the friction material 70. Preferably, the elastic force of the spring forming the biasing portion 50 is large enough to generate a braking force that maintains the stop of a vehicle stopped on an incline, for example. Furthermore, the biasing member 51 can be any elastic body and is not limited to a coil spring.

[0033] In the example shown, when the brake device 100 is activated, the friction material 70 is separated from the material to be frictioned 90, and when the electric motor 20 rotates in the forward direction, the point 10a of the arm 10 is pulled toward the rotary-to-linear conversion mechanism 40 via the reduction mechanism 30 and the rotary-to-linear conversion mechanism 40, causing the friction material 70 to move toward the material to be frictioned 90. However, the example is not limited to this. The arrangement of the electric motor 20, reduction mechanism 30, rotary-to-linear conversion mechanism 40, etc. may be changed so that when the point 10a is pushed toward the rotary-to-linear conversion mechanism 40 by the forward rotation of the electric motor 20, the arm 10 rotates around the pivot point 10f, causing the friction material 70 to move toward the material to be frictioned 90. In this configuration, when the electric motor 20 rotates in the reverse direction, point 10a on the arm 10 is pulled toward the rotary-to-linear motion conversion mechanism 40, causing the arm 10 to rotate around the pivot point 10f, and the friction material 70 moves toward the material to be frictioned 90.

[0034] Although the brake device 100 is shown to have a rotation-to-linear motion conversion mechanism 40, the configuration for transmitting the driving force of the electric motor 20 to point 10a on the arm 10 is not limited to this. For example, a cam mechanism may be used to convert rotational motion into reciprocating motion for transmission. Alternatively, the driving force of the electric motor 20 may be transmitted by converting rotational motion into linear motion via a chain or the like.

[0035] In the example shown, the biasing unit 50 is integrated with the electric motor 20, reduction mechanism 30, etc., and housed in a case (not shown), but it is not limited to this. It may also be independently fixed to the vehicle's bogie frame or suspension system.

[0036] The holding mechanism 60 is configured to maintain the stored energy state of the biasing unit 50 when energized and release the stored energy state when energized, but the reverse logic is also acceptable. That is, it may be configured to maintain the stored energy state of the biasing unit 50 when energized and release the stored energy state when energized. In this configuration, in order to release the stored energy state of the biasing unit 50 even if an unintended power outage occurs in the power supply that normally supplies power to the holding mechanism 60, etc., it is preferable to provide an independent power supply, such as a backup power supply, separate from the power supply that normally supplies power to the holding mechanism 60, etc., and a detection unit that detects power outages. When the detection unit detects a power outage, it is preferable to start supplying power to the backup power supply and energizing the holding mechanism 60.

[0037] Furthermore, the holding mechanism 60 may be configured to hold or release the stored energy state of the biasing member 51 by means of a solenoid and a claw or pin driven by the solenoid. In this case, for example, when the power supply to the solenoid is interrupted, the claw or pin engaged with the biasing member 51 is released, causing the stored energy of the biasing member 51 to exert its biasing force.

[0038] The electric motor 20 is not limited to an AC motor; it may also be a DC motor, a brushless DC motor, or the like. Although an example is shown where the electric motor 20 is coupled to a reduction gear 30, the reduction gear 30 may be omitted depending on the torque and rotational speed generated by the electric motor 20. Furthermore, an electric actuator may be used instead of the electric motor 20 and the rotary-to-linear motion conversion mechanism 40.

[0039] Furthermore, the brake device 100 may have a hanger that engages with the base of the friction material 70 and the case of the brake device 100 in order to suppress the displacement of the friction material 70 against the tangential tensile force on the friction material 70 that is generated when the friction material 70 and the friction material 90 come into contact. Also, the brake device 100 may be a tread brake device in which the friction material 90 is a wheel, or a disc brake in which the friction material 90 is a disc that rotates with the movement of the vehicle.

[0040] The configurations shown in the above embodiments are merely examples, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention.

[0041] 10 Arm 20 Electric motor 30 Reducer 40 Rotary-to-linear motion conversion mechanism 50 Biasing unit 60 Holding mechanism 70 Friction material 100 Brake device.

Claims

1. A brake device for a railway vehicle comprising: an arm having a pivot point; an electric motor that drives and rotates one end of the arm; a biasing member disposed at the other end of the arm, which pushes and rotates the arm when the stored energy state is released; a holding mechanism that maintains or releases the stored energy state of the biasing member according to the energization state; and a friction material engaged between the pivot point of the arm and the biasing member.

2. The brake device according to claim 1, characterized in that the holding mechanism holds the biasing member in an energized state when energized and releases the energized state of the biasing member when not energized.

3. The brake device according to claim 1, characterized in that the holding mechanism holds the biasing member in an energized state when no power is supplied and releases the energized state of the biasing member when power is supplied.

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