Patent Description:
<CIT> shows a railway vehicle equipped with an electric brake and a machine brake, wherein a transition between the electric brake and the machine brake is controlled.

Railway vehicles are equipped with a brake device that applies the brakes on the wheels. When the railway vehicle is traveling, the brake device is in a release state in which the brakes on the wheels are released. Patent Literature <NUM> describes a detection device for detecting insufficient release of the brakes of the brake device. This detection device detects the insufficient brake release of the brake device through temperature of the wheel while the railway vehicle is traveling.

To detect the insufficient brake release by the brake device, the detection device of Patent Literature <NUM> requires the railway vehicle to be traveling while the brake device is in the insufficient release state. Therefore, it is desired to be able to determine the insufficient brake release by the brake device even when the railway vehicle is not traveling.

This object is achieved by a brake control device according to the features of claim <NUM>, a brake control method according to claim <NUM>, and a brake control program according to claim <NUM>. According to one aspect disclosed herein, provided is a brake control device for applying a brake to a railway vehicle provided with a target member by pressing a frictional member against the target member. The brake control device includes: a detection unit detecting whether it is in a brake application state in which the frictional member is pressed against the target member; an acquiring unit acquiring a brake release command for releasing the pressing of the target member by the frictional member; and a determination unit determining whether the brake application state is maintained by using a detection result provided by the detection unit after the acquiring unit has acquired the brake release command.

In the above configuration, whether the brake is kept being applied is determined after the brake release command has been acquired. Therefore, unlike the prior arts in which the insufficient brake release cannot be determined unless the temperature of the wheels rise while the railway vehicle travels, it is possible to determine the insufficient brake release even when the railway vehicle is not running.

In the above brake control device, the detection unit may determine whether the brake application state is maintained based on a physical quantity. The physical quantity is at least one selected from the group consisting of: a force applied to the frictional member in the brake application state, a force applied to a transmission member in the brake application state, a displacement of the frictional member, and a displacement of the transmission member.

In the above brake control device, the determination unit may determine whether the brake application state is maintained based on a change in the physical quantity during a predetermined time period, the predetermined time period being the length of time from when the brake release command is acquired to when the brake is actually released in a normal state.

In the above brake control device, the determination unit may determine whether the brake application state is maintained by comparing the physical quantity with a previous physical quantity. The above brake control device further includes a control unit controlling driving of an electric actuator. The frictional member is driven by the electric actuator via the transmission member. When the determination unit determines that the brake application state is maintained, the control unit drives the electric actuator again in a direction in which the pressing by the frictional member is released.

In the above brake control device, when the determination unit determines that the brake application state is maintained, the control unit may once drive the electric actuator in a direction opposite to the direction in which the pressing by the frictional member is released, and then drive the electric actuator in the direction in which the pressing by the frictional member is released.

The above brake control device may include a control unit controlling an anti-skid valve. The frictional member is driven by a pressure supplied from a pressure source via a relay valve and the anti-skid valve. The control unit may drive the frictional member in a direction in which the pressing by the frictional member is released by exhausting through the anti-skid valve when the determination unit determines that the brake application state is maintained.

In the above brake control device, a plurality of the detection units may be provided on at least one of the frictional member or the transmission member, and each of the plurality of detection units detects a force applied to the at least one of the frictional material or the transmission member in the brake application state. The determination unit may predict a failure from a difference between physical quantities detected by the plurality of detection units.

In the above brake control device, the determination unit may predict a failure due to a malfunction based on an elapsed time from when the command acquiring unit acquires the brake release command to when the brake is actually released.

According to one aspect disclosed herein, provided is a brake control method for applying a brake to a railway vehicle provided with a target member by pressing a frictional member against the target member. The method includes: a detection step of detecting whether it is in a brake application state in which the frictional member is pressed against the target member; an acquiring step of acquiring a brake release command for releasing the pressing of the target member by the frictional member; and a determination step of determining whether the brake application state is maintained by using a detection result provided by the detection unit after the acquiring unit has acquired the brake release command.

A brake control program for applying a brake to a railway vehicle provided with a target member by pressing a frictional member against the target member, the program causing a computer to perform: a detection step of detecting whether it is in a brake application state in which the frictional member is pressed against the target member; an acquiring step of acquiring a brake release command for releasing the pressing of the target member by the frictional member; and a determination step of determining whether the brake application state is maintained by using a detection result provided by the detection unit after the acquiring unit has acquired the brake release command.

According to the above program, whether the brake is kept being applied is determined after the brake release command has been acquired. Therefore, unlike the prior arts in which the insufficient brake release cannot be determined unless the temperature of the wheels rise while the railway vehicle travels, it is possible to determine the insufficient brake release even when the railway vehicle is not running.

An insufficient brake release determination device for determining insufficient brake release of a brake device that applies a brake to a railway vehicle provided with a target member by pressing a frictional member against the target member. The insufficient brake release determination device includes: a detection unit detecting whether it is in a brake application state in which the frictional member is pressed against the target member; a detection unit detecting whether it is in a brake application state in which the frictional member is pressed against the target member; a determination unit determining whether the brake application state is maintained by using a detection result provided by the detection unit after the acquiring unit has acquired the brake release command.

According to the aspects of the inventions, it is possible to determine the insufficient brake release even when the railway vehicle is not running.

With reference to <FIG>, a first embodiment of a brake device equipped with a brake control device and an insufficient brake release determination device will be described. The brake device is provided in railway vehicles.

As shown in <FIG>, the brake device <NUM> is a tread brake for pressing a brake shoe <NUM> against the tread surface 2a of a wheel <NUM> of a railway vehicle, so that a braking force is generated. The brake device <NUM> includes a rotating motor <NUM> and is driven by the motor <NUM>. The brake device <NUM> includes a transmission member <NUM> and a brake shoe retainer <NUM>. The transmission member <NUM> is configured to transmit the driving force of the motor <NUM> to the brake shoe <NUM>. The transmission member <NUM> uses the driving force from the motor <NUM> to move the brake shoe retainer <NUM> in the radial direction of the wheel <NUM>. The brake shoe <NUM> is attached onto the brake shoe retainer <NUM>. The brake shoe <NUM> is moved as the brake shoe retainer <NUM> is moves, so that the brake shoe <NUM> is pressed against the tread surface 2A of the wheel <NUM>. As pressed against the tread surface 2A of the wheel <NUM>, the brake shoe <NUM> wars out. As a result, the brake shoe <NUM> becomes thinner. Here, the motor <NUM> is equivalent to an electric actuator. The wheel <NUM> is equivalent to a target member, and the brake shoe <NUM> is equivalent to the frictional member.

The brake device <NUM> is controlled by a control device <NUM>. The control device <NUM> may be formed of one or more processors that perform various processes in accordance with computer programs (software). The processes to be executed by the control device <NUM> or processors include a brake control method. The brake control method includes a brake application state detection process and an inflexibility determination process, which will be described later. The control device <NUM> may be formed of one or more dedicated hardware circuits such as application-specific integrated circuits (ASICs) that perform at least a part of the various processes, or it may be formed of circuitry including a combination of such circuits. The processors include a CPU and a memory such as a RAM or ROM. The memory stores program codes or instructions configured to cause the CPU to perform processes. The memory, or a computer-readable medium, encompasses any kind of available media accessible via a general-purpose or dedicated computer. The programs stored in the computer-readable storage medium include a brake control program. The brake control program causes the computer to execute a detection step, an acquisition step, and a determination step. The control device <NUM> corresponds to the brake control device and the insufficient brake release determination device.

The control device <NUM> controls the braking force based on a brake command from a vehicle control panel <NUM>. The control device <NUM> includes a control unit <NUM> for controlling the brake device <NUM>. The control unit <NUM> drives and controls the motor <NUM> according to a required braking force. The control unit <NUM> performs a control such that the brake shoe <NUM> moves from a position where it contacts the tread surface 2A of the wheel <NUM> to a position where it is at a predetermined distance from the tread surface 2A. With this control, the time until braking is initiated by bringing the brake shoe <NUM> into contact with the tread 2A of the wheel <NUM> can be made constant. A stress sensor 12A is provided in the transmission member <NUM>. The stress sensor 12A is, for example, a strain gage that measures a force applied to the transmission member <NUM> and provides measurement information to the control device <NUM>. Thus, the control device <NUM> is able to obtain information about the force applied to the transmission member <NUM> in the brake application state. Similarly, a stress sensor 13A is provided in the brake shoe retainer <NUM>. The stress sensor 13A is, for example, a strain gage that measures a force applied to the brake shoe retainer <NUM> and provides measurement information to the control device <NUM>. Thus, the control device <NUM> is able to obtain information about the force applied to the brake shoe <NUM> in the brake application state. Since the stress is almost zero when the brake is released, a threshold value may be set and the release of the brake may be detected when the acquired force falls below the threshold value. A stress sensor may be provided on the brake shoe <NUM> to measure the force applied to the brake shoe <NUM> when the brake is applied.

The control device <NUM> includes a drive information acquiring unit <NUM>, a storage unit <NUM>, and a command acquiring unit <NUM> as an acquiring unit, <NUM> and a determination unit <NUM>. The drive information acquiring unit <NUM> obtains drive information of the motor <NUM>. The drive information acquiring unit <NUM> calculates displacements of the transmission member <NUM> and the brake shoe <NUM> based on at least one of the product of the duration and the current of the motor <NUM> (i.e., the product of the value of the current flowing through the motor <NUM> and the period of time during which the current flows through the motor <NUM>) or the rotation speed of the motor <NUM>. The driving information acquiring unit <NUM> is configured to acquire measurement information provided by the stress sensors 12A and 13A. The drive information acquiring unit <NUM> calculates the force applied to the transmission member <NUM> in the brake application state from the measurement information provided by the stress sensor 12A. The drive information acquiring unit <NUM> also calculates the force applied to the brake shoe <NUM> in the brake application state from the measurement information provided by the stress sensor 13A.

The drive information acquiring unit <NUM> detects whether it is in the brake application state in which the brake shoe <NUM> is pressed against the tread surface 2A of the wheel <NUM>. In other words, the drive information acquiring unit <NUM> detects whether the brake is applied through a physical quantity(ies). The physical quantity may be at least one selected from the group consisting of: the force applied to the brake shoe <NUM> in the brake application state, the force applied to the transmission member <NUM> in the brake application state, the displacement of the brake shoe <NUM>, and the displacement of the transmission member <NUM>. In the storage unit <NUM>, the displacement of the transmission member <NUM>, the displacement of the brake shoe <NUM>, the force applied to the transmission member <NUM>, and the force applied to the brake shoe <NUM> are stored. The command acquiring unit <NUM> obtains, from the vehicle control panel <NUM>, a release command for releasing the press against the tread surface 2A of the wheel <NUM> by the brake shoe <NUM>. The drive information acquiring unit <NUM> corresponds to a detection unit that detects whether it is in the brake application state.

After the command acquiring unit <NUM> has acquired the brake release command, the determination unit <NUM> uses a detection result of the drive information acquiring unit <NUM> to determine whether the application of the brake is maintained or not. The determination unit <NUM> obtains a change in the physical quantity during a predetermined period of time, which is the length of time of the normal state from when the brake release command is obtained to when the brake is actually released. The determination unit <NUM> determines whether the application of the brake is maintained based on the obtained change in the physical quantity. The change(s) in the physical quantity(ies) during the predetermined time period in the normal state is stored in the storage unit <NUM>. When the obtained change in the physical quantity during the predetermined time period is same as the change in the physical quantity during the predetermined time period in the normal state stored in the storage unit <NUM>, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. Alternatively, the determination unit <NUM> acquires the physical quantity and determines whether the application of the brake is maintained by comparing a currently acquired value of the physical quantity with a previously acquired value of the physical quantity. The values of the physical quantity obtained in the past are stored in the storage unit <NUM>. When the acquired physical quantity matches a previous physical quantity obtained at the time of the brake release and stored in the storage unit, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. The determination unit <NUM> may determine whether the application of the brake is maintained based on at least one of the change in the physical quantity during the predetermined time period in the normal state or the previous physical quantity.

When the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> drives the motor <NUM> again in the direction in which the pressing by the brake shoe <NUM> is released. By retrying in this way, the possibility of the brake release can be increased. Alternatively, when the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> once drives the motor <NUM> in a direction opposite to the direction in which the pressing by the brake shoe <NUM> is released, and then drives the motor <NUM> in the direction in which the pressing by the brake shoe <NUM> is released. When there is sticking or jam in the transmission member <NUM>, driving the brake shoe <NUM> in the direction opposite to the direction in which the brake shoe is detached may eliminate the sticking or jam. Therefore, when the transmission member <NUM> is jammed and the brake shoe <NUM> does not operate, it is possible to increase the possibility that the jam is released and pressing by the brake shoe <NUM> is released.

The brake device <NUM> includes the informing unit <NUM>. The informing unit <NUM> informs the insufficient brake release when the release of the brake becomes insufficient at the time when the brake is supposed to be completely released. The informing unit <NUM> may be a speaker that emits sound, an alert lamp that lights, a display, and the like. It is preferable that the informing unit <NUM> is provided on the vehicle control panel <NUM> to allow the driver to easily notice the informing unit. Alternatively, it is preferable that the informing unit <NUM> is installed near the brake device <NUM> to allow an operator to notice it at the time of start-up inspection, work inspection, or the like.

The following now describes the steps of the brake application state detection process performed by the control device <NUM>, with reference to <FIG> illustrates a process for the brake device <NUM> to detect the brake application state when the brake device <NUM> is activated. The brake device <NUM> stores the processing.

The control device <NUM> first acquires the drive information (step S1). That is, the drive information acquiring unit <NUM> acquires at least one of the current value of the motor <NUM> or the rotation speed of the motor <NUM>. Further, the drive information acquiring unit <NUM> acquires the measurement information of the stress sensors 12A and 13A.

Subsequently, the control device <NUM> calculates one or more physical quantities (step S2). Specifically, the drive information acquiring unit <NUM> calculates the displacements of the transmission member <NUM> and the brake shoe <NUM> based on at least one of the product of the duration and the current of the motor <NUM> or the rotation speed of the motor <NUM>. The drive information acquiring unit <NUM> calculates the force applied to the transmission member <NUM> in the brake application state from the measurement information provided by the stress sensor 12A. The drive information acquiring unit <NUM> also calculates the force applied to the brake shoe <NUM> in the brake application state from the measurement information provided by the stress sensor 13A.

Subsequently, the control device <NUM> stores the one or more physical quantities (step S3) and ends the process. That is, the drive information acquiring unit <NUM> stores, in the storage unit <NUM>, the displacements and the forces applied in the brake application state. Once the drive information acquiring unit <NUM> acquires the brake release command, the drive information acquiring unit <NUM> acquires the change(s) in the one or more physical quantities in the predetermined time period and stores them in the storage unit <NUM>.

The following now describes the steps of the insufficient brake release determination process performed by the control device <NUM>, with reference to <FIG> shows the process of determining whether the release of the brake is insufficient when the brake release command is acquired from the vehicle control panel <NUM>.

The control device <NUM> first determines whether the brake release command is acquired when the railroad vehicle is stopped (step S11). Specifically, the control unit <NUM> determines whether the command acquiring unit <NUM> has acquired the brake release command from the vehicle control panel <NUM>. When the control unit <NUM> determines that the brake release command has not been acquired (step S11: NO), the control unit <NUM> waits until the brake release command is acquired.

Whereas when it is determined that the brake release command has been acquired (step S11: YES), the control unit <NUM> performs a release operation to release the brake (step S12). That is, the control unit <NUM> drives and controls the motor <NUM> to move the brake shoe <NUM> in the direction away from the tread surface 2A of the wheel <NUM>. Step S12 corresponds to the acquisition step.

Subsequently, the control device <NUM> performs the brake application state detection process described above (step S13). That is, the drive information acquiring unit <NUM> acquires a change(s) in the physical quantity(ies) during the predetermined time period starting from the receipt of the brake release command or the physical quantity(ies) after the elapse of the predetermined time period. Step S13 corresponds to the detection step.

Subsequently, the control unit <NUM> determines whether the brake is being applied (step S24). Specifically, the determination unit <NUM> determines whether the application of the brake is maintained based on the change in the physical quantity during the predetermined time period starting from the receipt of the brake release command. When the obtained change in the physical quantity is same as the change in the physical quantity of the normal state stored in the storage unit <NUM>, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. Alternatively, the determination unit <NUM> determines whether the application of the brake is maintained by comparing the currently acquired value of the physical quantity with a previously acquired value of the physical quantity. When the acquired physical quantity matches the previous physical quantity that has been obtained at the time of the brake release and stored in the storage unit, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. The determination unit <NUM> determines that the brake is not applied (step S14: NO), and determines that the brake is "released" (step S19), and ends the process. Step S14 corresponds to the determination step.

Whereas when the acquired change in the physical quantity does not match the change in the physical quantity of the normal state, the determination unit <NUM> determines that the application of the brake is maintained because the brake has not been released. Alternatively, when the currently acquired value of the physical quantity does not match the previous value of the physical quantity, the determination unit <NUM> determines that the application of the brake is maintained because the brake has not been released. When the determination unit <NUM> determines that the brake is applied (step S14: YES), the determination unit <NUM> determines whether the number of determinations performed is less than a predetermined number (step S15). That is, the control unit <NUM> retries the release operation until the number of times it is determined that the application of the brake is maintained reaches the predetermined number of times. When it is determined that the number of times it is determined that the application of the brake is maintained is less than the predetermined number of times (step S15: YES), the control unit <NUM> drives the motor <NUM> in the direction opposite to that of the brake release operation (step S16). The process then proceeds to step S12. That is, by driving the motor <NUM> in the direction opposite to that of the brake release operation, the control unit <NUM> increases the possibility that the transmission member <NUM> and the brake shoe <NUM> are released from the state of being jammed due to foreign matters, or the like. The control unit <NUM> retries the brake release operation in step S12.

Whereas when the control unit <NUM> determines that the number of determinations performed is equal to or greater than the predetermined number (step S15: NO), the control unit <NUM> determines that the release of the brake is insufficient (step S17), and outputs the "insufficient brake release" (step S18). That is, the control unit <NUM> gives up the retry and processes as the "insufficient brake release" because the application of the brake is maintained even after the motor <NUM> is driven in the direction opposite to that of the brake release operation and the brake release operation is performed at the predetermined number of times. Subsequently, the control unit <NUM> informs the "insufficient brake release" by the informing unit <NUM>. In this way, it is possible to determine the insufficient brake release even when the railway vehicle is not traveling. In addition, the vehicle control panel <NUM> may prevent the start of the railway vehicle.

Advantageous effects of the first embodiment will be now described.

With reference to <FIG>, the second embodiment of the brake device equipped with the brake control device and the insufficient brake release determination device will be described. The second embodiment is different from the first embodiment in that the brake device is a disc brake device. The following description will be focused on the differences from the first embodiment.

As shown in <FIG>, a brake device <NUM> is a disc brake for generating a braking force by pressing brake pads 34A and 34B against a disc <NUM> integrally rotating with the wheel <NUM> of the railway vehicle. The brake device <NUM> includes a rotating motor <NUM> and is driven by the motor <NUM>. The brake device <NUM> includes a transmission member <NUM> for transmitting the driving force of the motor <NUM> and also includes a left arm 33A and right arm 33B. The transmission member <NUM> uses the driving force from the motor <NUM> to move the left and right arms 33A and 33B. The brake pad 34A is attached to the left arm 33A, and the brake pad 34B is attached to the right arm 33B. The left and right arms 33A and 33B are vertically moved by the transmission member <NUM> toward the side surface 3A of the disc <NUM>. The brake pads 34A and 34B are displaced with the left and right arms 33A and 33B, so that the brake pads 34A and 34B are pressed against the side surface 3A of the disc <NUM>. As pressed against the side surface 3A of the disc <NUM>, the brake pads 34A and 34B wear out. As a result, the brake pads 34A and 34B become thinner. Here, the motor <NUM> is equivalent to an electric actuator. The disc <NUM> is a rotatable member and equivalent to a target member, and the brake pads 34A and 34B are equivalent to the frictional member. The wheel <NUM> may be used as the frictional member instead of the disc <NUM>.

The brake device <NUM> is controlled by a controller device <NUM>, which is configured in the same manner as in the first embodiment. The control device <NUM> controls the braking force based on a braking command from a vehicle control panel <NUM>. The control device <NUM> includes a control unit <NUM> for controlling the brake device <NUM>. The control unit <NUM> drives and controls the motor <NUM> according to a required braking force. When releasing the brake, the control unit <NUM> controls the motor <NUM> such that the brake pads 34A and 34B can move a predetermined distance from the position where they contact the side surface 3A of the disc <NUM>. In this way, after the brake pads 34A and 34B are brought into contact with the side surface 3A of the disc <NUM>, the braking starts working after the same period of time. A stress sensor 32A is provided in the transmission member <NUM>. The stress sensor 32A is, for example, a strain gage that measures a force applied to the transmission member <NUM> and provides measurement information to the control device <NUM>. Thus, the control device <NUM> is able to obtain information about the force applied to the transmission member <NUM> in the brake application state. Similarly, the left arm 33A is provided with a stress sensor 33C. The stress sensor 33C is, for example, a strain gage that measures a force applied to the left arm 33A and provides measurement information to the control device <NUM>. Thus, the control device <NUM> is able to obtain information about the force applied to the brake pads 33A and 34B in the brake application state. Since the stress is almost zero when the brake is released, a threshold value may be set and the release of the brake may be detected when the acquired force falls below the threshold value. Stress sensors may be provided on the brake pads 33A and 34B to measure the forces applied to the brake pads 33A and 34B when the brake is applied.

The control device <NUM> includes the drive information acquiring unit <NUM>, the storage unit <NUM>, and the command acquiring unit <NUM>, and the determination unit <NUM>. The drive information acquiring unit <NUM> obtains drive information of the motor <NUM>. The drive information acquiring unit <NUM> calculates the displacements of the transmission member <NUM> and the brake pads 34A and 34B based on at least one of the product of the duration and the current of the motor <NUM> or the rotation speed of the motor <NUM>. Further, the drive information acquiring unit <NUM> acquires the measurement information of the stress sensors 32A and 33C. The drive information acquiring unit <NUM> calculates the force applied to the transmission member <NUM> in the brake application state from the measurement information provided by the stress sensor 32A. The drive information acquiring unit <NUM> also calculates the forces applied to the brake pads 34A and 34B in the brake application state from the measurement information provided by the stress sensor 33C.

The drive information acquiring unit <NUM> detects whether it is in the brake application state where the brake pads 34A and 34B are pressed against the tread surfaces 3A of the disc <NUM>. In other words, the drive information acquiring unit <NUM> detects whether the brake is applied through a physical quantity. The physical quantity may be at least one selected from the group consisting of: the forces applied to the brake pads 34A and 34B in the brake application state, the force applied to the transmission member <NUM> in the brake application state, the displacements of the brake pads 34A and 34B, and the displacement of the transmission member <NUM>. In the storage unit <NUM>, the displacement of the transmission member <NUM>, the displacements of the brake pads 34A and 34B, the force applied to the transmission member <NUM>, and the forces applied to the brake pads 34A and 34B are stored. The command acquiring unit <NUM> obtains, from the vehicle control panel <NUM>, a brake release command for releasing the press against the tread surfaces 3A of the disc <NUM> by the brake pads 34A and 34B. The drive information acquiring unit <NUM> corresponds to a detection unit that detects whether the brake is applied.

After the command acquiring unit <NUM> obtains the brake release command, the determination unit <NUM> uses a detection result of the drive information acquiring unit <NUM> to determine whether the application of the brake is maintained or not. The determination unit <NUM> obtains a change in the physical quantity during a predetermined period of time, which is the length of time of the normal state from when the brake release command is obtained to when the brake is actually released. The determination unit <NUM> determines whether the application of the brake is maintained based on the obtained change in the physical quantity. The change in the physical quantity in the predetermined period of time in the normal state is stored in the storage unit <NUM>. When the obtained change in the physical quantity in the predetermined period of time is same as the change in the physical quantity at the predetermined period of time in the normal state stored in the memory section <NUM>, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. Alternatively, the determination unit <NUM> acquires the physical quantity and determines whether the application of the brake is maintained by comparing a currently acquired value of the physical quantity with a previously acquired value of the physical quantity. The values of the physical quantity obtained in the past are stored in the storage unit <NUM>. When the acquired physical quantity matches a previous physical quantity obtained at the time of the brake release and stored in the storage unit, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. The determination unit <NUM> may determine whether the brake application state is maintained based on at least one of the change in the physical quantity during the predetermined time period in the normal state or the previous physical quantity. When the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> drives the motor <NUM> again in the direction of detaching the brake pads 34A and 34B. By retrying in this way, the possibility of the brake release can be increased. Alternatively, when the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> once drives the motor <NUM> in a direction opposite to the direction in which the pressing by the brake pads 34A and 34B are released, and then drives the motor <NUM> in the direction in which the pressing by the brake pads 34A and 34B are released. When there is sticking or jam in the transmission member <NUM>, driving the brake pads 34A and 34B in the direction opposite to the direction in which the pressing by the brake pads 34A and 34B are released may eliminate the sticking or jam. Therefore, when the transmission member <NUM> is jammed and the brake pads 34A and 34B do not operate, it is possible to increase the possibility that the jam is released and pressing by the brake pads 34A and 34B are released.

When the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> drives the motor <NUM> again in the direction of detaching the brake pads 34A and 34B. By retrying in this way, the possibility of the brake release can be increased. Alternatively, when the determination unit <NUM> determines that the brake application is maintained, the control unit <NUM> once drives the motor <NUM> in a direction opposite to the direction in which the pressing by the brake pads 34A and 34B are released, and then drives the motor <NUM> in the direction in which the pressing by the brake pads 34A and 34B are released. When there is sticking or jam in the transmission member <NUM>, driving the brake pads 34A and 34B in the direction opposite to the direction in which the pressing by the brake pads 34A and 34B are released may eliminate the sticking or jam. Therefore, when the transmission member <NUM> is jammed and the brake pads 34A and 34B do not operate, it is possible to increase the possibility that the jam is released and pressing by the brake pads 34A and 34B are released.

The control device <NUM> first acquires the drive information (step S1). That is, the drive information acquiring unit <NUM> acquires at least one of the current value of the motor <NUM> or the number of rotations of the motor <NUM>. Further, the drive information acquiring unit <NUM> acquires the measurement information of the stress sensors 32A and 33C.

Subsequently, the control device <NUM> calculates one or more physical quantities (step S2). Specifically, the drive information acquiring unit <NUM> calculates the displacements of the transmission member <NUM> and the brake pads 34A and 34B based on at least one of the product of the duration and the current of the motor <NUM> or the rotation speed of the motor <NUM>. The drive information acquiring unit <NUM> calculates the force applied to the transmission member <NUM> in the brake application state from the measurement information provided by the stress sensor 32A. The drive information acquiring unit <NUM> also calculates the forces applied to the brake pads 34A and 34B in the brake application state from the measurement information provided by the stress sensor 33C.

Whereas when it is determined that the brake release command has been acquired (step S11: YES), the control unit <NUM> performs a brake release operation to release the brake (step S12). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake pads 34A and 34B away from the side surfaces 3A of the disc <NUM>. Step S12 corresponds to the acquisition step.

Subsequently, the control unit <NUM> determines whether the brake is being applied (step S24). Specifically, the determination unit <NUM> determines whether the application of the brake is maintained based on the change in the physical quantity during the predetermined time period starting from the receipt of the brake release command. When the obtained change in the physical quantity is same as the change in the physical quantity of the normal state stored in the storage unit <NUM>, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. Alternatively, the determination unit <NUM> determines whether the application of the brake is maintained by comparing the currently acquired value of the physical quantity with a previously acquired value of the physical quantity. When the acquired physical quantity matches a previous physical quantity obtained at the time of the brake release and stored in the storage unit, the determination unit <NUM> determines that the application of the brake is not maintained since the brake is released. The determination unit <NUM> determines that the brake is not applied (step S14: NO), and determines that the brake is "released" (step S19), and ends the process. Step S14 corresponds to the determination step.

Whereas when the acquired change in the physical quantity does not match the change in the physical quantity of the normal state, the determination unit <NUM> determines that the application of the brake is maintained because the brake has not been released. Alternatively, when the acquired value of the physical quantity does not match the previous value of the physical quantity, the determination unit <NUM> determines that the application of the brake is maintained because the brake has not been released. When the determination unit <NUM> determines that the brake is applied (step S14: YES), the determination unit <NUM> determines whether the number of determinations performed is less than a predetermined number (step S15). That is, the control unit <NUM> retries the release operation until the number of times it is determined that the application of the brake is maintained reaches the predetermined number of times. When it is determined that the number of times it is determined that the application of the brake is maintained is less than the predetermined number of times (step S15: YES), the control unit <NUM> drives the motor <NUM> in the direction opposite to that of the brake release operation (step S16). The process then proceeds to step S12. That is, by driving the motor <NUM> in the direction opposite to that of the brake release operation, the control unit <NUM> increases the possibility that the transmission member <NUM> and the brake pads 34A and 34B are released from the state of being jammed due to foreign matters, or the like. The control unit <NUM> retries the brake release operation in step S12.

Advantageous effects of the second embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effects (<NUM>-<NUM>) to (<NUM>-<NUM>) of the first embodiment.

With reference to <FIG>, the third embodiment of the brake device equipped with the brake control device and the insufficient brake release determination device will be described. The third embodiment is different from the first embodiment in that the drive source is compressed air. The following description will be focused on the differences from the first embodiment.

As shown in <FIG>, in the brake device <NUM>, compressed air is supplied from a pressure source <NUM> to an air cylinder <NUM> via a relay valve <NUM> and an anti-skid valve <NUM>. The anti-skid valve <NUM> is a valve for exhausting the compressed air supplied to the air cylinder <NUM> when the wheels skid relative to the track. The brake device <NUM> may be a tread brake device or a disc brake device. When the compressed air is supplied, the air cylinder <NUM> drives the frictional member <NUM> in the brake application direction via the transmission member <NUM>. Once the compressed air is exhausted, the air cylinder <NUM> drives the frictional member <NUM> via the transmission member <NUM> in a direction of the brake release which is opposite to the brake application direction.

A stress sensor (not shown) is provided on the transmission member <NUM> and the frictional member <NUM>, and the forces applied to the transmission member <NUM> and the frictional member <NUM> are outputted to the control device <NUM>. In the control device <NUM>, the determination unit <NUM> performs the insufficient brake release determination process as in the first embodiment and the second embodiment. When the determination unit <NUM> determines that the application of the brake is maintained and the brake release is insufficient through the determination process, the control unit <NUM> causes the anti-skid valve <NUM> to exhaust the air. When the air is exhausted from the anti-skid valve <NUM>, the frictional member <NUM> is driven in the brake release direction via the air cylinder <NUM> and the transmission member <NUM>.

Advantageous effects of the third embodiment will be now described. The following advantageous effects are obtained in addition to the advantageous effects (<NUM>-<NUM>) to (<NUM>-<NUM>) of the first embodiment.

(<NUM>-<NUM>) By exhausting the compressed air through the anti-skid valve <NUM> to drive the frictional member <NUM> in a direction to release the brake, the possibility of the complete brake release can be increased even when a malfunction of the relay valve <NUM> occurs.

With reference to <FIG>, the fourth embodiment of the brake device equipped with the brake control device will now be described. The fourth embodiment is different from the first to third embodiment in that a failure prediction process is performed. The following description will be focused on the differences from the first embodiment. Although the brake device <NUM> will be hereunder described as the fourth embodiment, the brake devices <NUM> and <NUM> may be used instead.

Since it is desirable that the railway vehicle does not travel while the insufficient brake release by the brake device <NUM> occurs, failure prediction of the brake device <NUM> is desired. To realize this, the determination unit <NUM> of the brake device <NUM> predicts a failure from a difference between physical quantities acquired by the drive information acquiring unit <NUM>. The physical quantities are a force applied to the brake shoe <NUM> in the brake application state measured by the stress sensor 13A of the brake shoe retainer <NUM>, and a force applied to the transmission member <NUM> in the brake application state measured by the stress sensor 12A of the transmission member <NUM>. The drive information acquiring unit <NUM> that acquires detection result from the stress sensors 12A and 13A corresponds to the detection unit. Two or more stress sensors may be provided in the transmission member <NUM>, or two or more stress sensors may be provided in at least one of the brake shoe retainer <NUM> or the brake shoe <NUM>.

Since these physical quantities are the same, the determination unit <NUM> compares two or more physical quantities. When there is a difference between the physical quantities, it is determined that a failure is predicted. Further, the determination unit <NUM> predicts a failure due to a malfunction based on the elapsed time from when the command acquiring unit <NUM> acquires the brake release command to when the brake is actually released. When the brake works normally, the elapsed time will be the same every time. Whereas if there is a malfunction, the elapsed time will be longer. The elapsed time becomes longer if parts movement becomes dull due to deterioration over time. Therefore, the determination unit <NUM> determines that a failure is predicted due to a malfunction when the elapsed time is different from the previous elapsed time. "A failure is predicted" means a state in which there is no failure but the possibility of failure is increasing. The determination unit <NUM> may determine that a failure is predicted based on at least one of two or more physical quantities or the elapsed time.

The control device <NUM> first acquires measurement information (step S21). The drive information acquiring unit <NUM> acquires the measurement information from the stress sensors 12A and 13A. Subsequently, the control device <NUM> calculates one or more physical quantities (step S22). Specifically, the drive information acquiring unit <NUM> calculates the force applied to the transmission member <NUM> in the brake application state from the measurement information provided by the stress sensor 12A. The drive information acquiring unit <NUM> also calculates the force applied to the brake shoe <NUM> in the brake application state from the measurement information provided by the stress sensor 13A.

Subsequently, the control device <NUM> store the one or more physical quantities (step S23). That is, the drive information acquiring unit <NUM> stores, in the storage unit <NUM>, the displacements and the forces applied in the brake application state. Once the drive information acquiring unit <NUM> acquires the brake release command, the drive information acquiring unit <NUM> acquires the change(s) in the one or more physical quantities in the predetermined time period and stores them in the storage unit <NUM>.

Subsequently, the control device <NUM> determines whether a failure is predicted, which means whether a possibility of failure is increased (step S24). The determination unit <NUM> determines whether a failure is predicted based on the two or more physical quantities. Further, the determination unit <NUM> predicts a failure due to a malfunction based on the elapsed time from when the command acquiring unit <NUM> acquires the brake release command to when the brake is actually released. Then, when the determination unit <NUM> determines that a failure is not predicted (step S24: NO), the determination unit <NUM> outputs "no failure predicted". That is, when the two or more physical quantities are the same and the elapsed time remains the same, the determination unit <NUM> determines that a failure is not predicted.

Whereas when the determination unit <NUM> determines that the failure is predicted (step S24: YES), the determination unit <NUM> outputs "a failure is predicted". That is, when the two or more physical quantities are different or the elapsed time changes, the determination unit <NUM> determines that a failure is predicted. Therefore, it is possible to predict a failure before insufficient brake release occurs. The control unit <NUM> informs that "failure is predicted" through the informing unit <NUM>.

Advantageous effects of the fourth embodiment will be now described. The fourth embodiment produces the following advantageous effects in addition to the effects (<NUM>-<NUM>) to (<NUM>-<NUM>) achieved by the first embodiment, the effects (<NUM>-<NUM>) and (<NUM>-<NUM>) achieved by the second embodiment, and the effect (<NUM>-<NUM>) achieved by the third embodiment.

(<NUM>-<NUM>) Since the forces relating to the brake shoe <NUM> and the transmission unit <NUM> to which the driving force is transmitted change in the same manner, it is possible to predict a failure based on their physical quantities are different from each other.

(<NUM>-<NUM>) By monitoring the elapsed time from the acquisition of the brake release command by the command acquiring unit <NUM> to when the brake is actually released, it is possible to predict a failure due to a malfunction.

Claim 1:
A brake control device (<NUM>) for applying a brake to a railway vehicle provided with a target member (<NUM>, <NUM>) by pressing a frictional member (<NUM>, 34A, 34B) against the target member (<NUM>, <NUM>), the brake control device (<NUM>) comprising:
a detection unit (<NUM>) detecting whether it is in a brake application state in which the frictional member (<NUM>, 34A, 34B) is pressed against the target member (<NUM>, <NUM>); and characterized in that it comprises
an acquiring unit (<NUM>) acquiring, when the railway vehicle is stopped, a brake release command for releasing the pressing of the target member (<NUM>, <NUM>) by the frictional member (<NUM>, 34A, 34B); and
a determination unit (<NUM>) determining, when the railway vehicle is stopped, whether the brake application state is maintained by using a detection result provided by the detection unit (<NUM>) after the acquiring unit (<NUM>) has acquired the brake release command.