Patent Description:
Patent Literature <NUM> discloses an electric brake device for applying a brake to a vehicle by using motor as a power source to press a brake block against a disc rotating integrally with the wheel.

Patent Literature <NUM> discloses an electronic parking brake system for controlling the activation or deactivation of the electronic parking brake and a control method.

Patent Literature <NUM>: US Application Publication <CIT>.

The electric brake device disclosed in Patent Literature <NUM> repeatedly performs the braking operation by pressing the brake block against the disc. This may cause friction between the brake block and the disc, as a result of which the brake block may wear out. If the brake block wears out beyond a predetermined amount, it needs to be replaced. To this end, brake devices using motors or other electric actuators as a drive source require that the wear amount of frictional members such as brake blocks be calculated. This issue arises not only in disc brakes but also in tread brakes, where frictional members are configured to be brought into contact with the tread surface of wheels.

To solve the above-described problems, a brake device is configured to apply a brake to a vehicle provided with a target member by using an electric actuator to drive a frictional member so that the frictional member is pressed against the target member. The brake device includes an acquiring unit for acquiring driving information regarding driving of the electric actuator, a travel distance calculating unit for, based on the acquired driving information, calculating a travel distance by which the frictional member travels to touch the target member, and a wear amount calculating unit for calculating a wear amount of the frictional member based on a currently calculated value of the travel distance and an old value of the travel distance.

As the frictional member, which is driven by the electric actuator, wears out, the frictional member must travel longer before touching the target member. With the above-described features, the driving information regarding the driving of the electric actuator is used to calculate the travel distance by which the frictional member travels to touch the target member. In this manner, the wear amount of the frictional member can be calculated based on the difference between the currently calculated value of the travel distance and an old value of the travel distance of the frictional member.

The above-described brake device preferably includes a sensor for detecting whether the frictional member is placed at a reference position for the travel distance of the frictional member. The acquiring unit preferably acquires detected information from the sensor, and the travel distance calculating unit preferably calculates a travel distance by which the frictional member travels from the reference position detected by the sensor to a position where the frictional member touches the target member.

In the above-described brake device, the reference position is preferably a fully opened position where the frictional member is the farthest away from the target member. In the above-described brake device, the travel distance calculating unit preferably calculates the travel distance of the frictional member based on at least one of a product of a duration and a current flowing through the electric actuator or a rotational rate of the electric actuator.

The above-described brake device preferably includes a target member wear amount acquiring unit for acquiring a wear amount of the target member. The wear amount calculating unit preferably takes the acquired wear amount of the target member into consideration in calculating the wear amount of the frictional member.

According to the invention, the above-described brake device includes a control unit for controlling driving of the electric actuator. The control unit controls the driving of the electric actuator such that the frictional member travels to a position that is at a predetermined distance from the position where the frictional member touches the target member.

According to the invention, in the above-described brake device, when the wear amount of the frictional member is greater than a wear amount of a frictional member of another brake device provided on another vehicle making up a same train, the control unit adjusts a braking force such that the braking force is less than a braking force of the other brake device.

In the above-described brake device, when the frictional member is newly mounted as a replacement, the brake device drives the frictional member so that the frictional member travels to touch the target member and acquires a travel distance by which the frictional member travels, and the acquired travel distance is used as the old value of the travel distance in calculating the wear amount.

The above-described brake device preferably includes an informing unit for issuing information when the wear amount of the frictional member becomes equal to or greater than a predetermined value. To solve the above-described problems, a method for calculating a wear amount of a frictional member of a brake device is provided. The brake device is configured to apply a brake to a vehicle provided with a target member by using an electric actuator to drive a frictional member so that the frictional member is pressed against the target member. The method includes steps of acquiring driving information regarding driving of the electric actuator, based on the acquired driving information, calculating a travel distance by which the frictional member travels to touch the target member, and calculating a wear amount of the frictional member based on a currently calculated value of the travel distance and an old value of the travel distance, and controlling driving of the electric actuator, wherein the control unit controls the driving of the electric actuator such that the frictional member travels to a position that is at a predetermined distance from the position where the frictional member touches the target member, and wherein, when the wear amount of the frictional member is greater than a wear amount of a frictional member of another brake device provided on another vehicle making up a same train, the control unit adjusts a braking force such that the braking force is less than a braking force of the other brake device.

As the frictional member, which is driven by the electric actuator, wears out, the frictional member must travel longer before touching the target member. According to the above-described method, the driving information regarding the driving of the electric actuator is used to calculate the travel distance by which the frictional member travels to touch the target member. In this manner, the wear amount of the frictional member can be calculated based on the difference between the currently calculated value of the travel distance and an old value of the travel distance of the frictional member.

To solve the above-described problems, a program for calculating a wear amount of a frictional member of a brake device is provided. The brake device is configured to apply a brake to a vehicle provided with a target member by using an electric actuator to drive a frictional member so that the frictional member is pressed against the target member. The program causes a computer to perform steps of acquiring driving information regarding driving of the electric actuator, based on the acquired driving information, calculating a travel distance by which the frictional member travels to touch the target member, and calculating a wear amount of the frictional member based on a currently calculated value of the travel distance and an old value of the travel distance, and controlling driving of the electric actuator, wherein the control unit controls the driving of the electric actuator such that the frictional member travels to a position that is at a predetermined distance from the position where the frictional member touches the target member, and wherein, when the wear amount of the frictional member is greater than a wear amount of a frictional member of another brake device provided on another vehicle making up a same train, the control unit adjusts a braking force such that the braking force is less than a braking force of the other brake device.

As the frictional member, which is driven by the electric actuator, wears out, the frictional member must travel longer before touching the target member. According to the above-described program, the driving information regarding the driving of the electric actuator is used to calculate the travel distance by which the frictional member travels to touch the target member. In this manner, the wear amount of the frictional member can be calculated based on the difference between the currently calculated value of the travel distance and an old value of the travel distance.

According to the present invention, the wear amount of the frictional member can be calculated.

With reference to <FIG>, the following describes a brake device relating to a first embodiment. The brake device is provided in a railroad vehicle.

As shown in <FIG>, a brake device <NUM> is a tread brake for generating a braking force by pressing a brake block <NUM> against a tread surface 2A of a wheel <NUM> of a railroad 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> and a brake block retainer <NUM>. The transmission member <NUM> is configured to transmit the driving force produced by the motor <NUM>. The transmission member <NUM> uses the driving force from the motor <NUM> to displace the brake block retainer <NUM> in the radial direction of the wheel <NUM>. The brake block <NUM> is attached onto the brake block retainer <NUM>. The brake block <NUM> is displaced as the brake block retainer <NUM> is displaced, so that the brake block <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 block <NUM> wars out. As a result, the brake block <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 block <NUM> is equivalent to the frictional member.

The brake device <NUM> is controlled by a controller device <NUM>. The controller 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 controller device <NUM> or processors include a method for calculating a wear amount. The wear amount calculation method includes a procedure for calculating a wear amount, described below. The controller 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 medium include a program for calculating a wear amount. The wear amount calculation program causes the computer to execute steps of acquiring, calculating a travel distance and calculating a wear amount.

The controller device <NUM> controls the braking force based on a braking command from a vehicle control console <NUM>. The controller device <NUM> includes a control unit <NUM> for controlling the brake device <NUM>. The control unit <NUM> controls driving of the motor <NUM> such that a necessary braking force is produced. The control unit <NUM> controls driving of the motor <NUM> such that the brake block <NUM> can move to a position at a predetermined distance away from a position where it can touch the tread surface 2A of the wheel <NUM>. In this way, the brake block <NUM> can touch the tread surface 2A of the wheel <NUM> and the braking can start within a constant period of time. The transmission member <NUM> is provided with a sensor 12A for detecting whether the brake block <NUM> is positioned at a reference position for the travel distance of the brake block <NUM>.

The controller device <NUM> includes a driving information acquiring unit <NUM>, a travel distance calculating unit <NUM>, and a wear amount calculating unit <NUM>. The driving information acquiring unit <NUM> is configured to acquire information related to driving of the motor <NUM>. The driving information acquiring unit <NUM> is configured to acquire information detected by the sensor 12A. The travel distance calculating unit <NUM> is configured to calculate the travel distance by which the brake block <NUM> travels to touch the tread surface 2A of the wheel <NUM>. The wear amount calculating unit <NUM> calculates the wear amount of the brake block <NUM> based on the currently calculated value of the travel distance and an old value of the travel distance.

The travel distance calculating unit <NUM> is configured to calculate the travel distance by which the brake block <NUM> travels from the reference position detected by the sensor 12A to a touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM>. The reference position is referred to as a fully opened position where the brake block <NUM> is the farthest away from the tread surface 2A of the wheel <NUM>. The travel distance calculating unit <NUM> calculates the travel distance by which the brake block <NUM> travels 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 rotational rate of the motor <NUM>. The control unit <NUM> can know that the brake block <NUM> reaches the touch position or touches the tread surface 2A of the wheel <NUM>, by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>. The travel distance calculating unit <NUM> may use a limit switch or the like to detect the touch position.

The travel distance calculating unit <NUM> can calculate the travel distance by which the brake block <NUM> travels in two different ways. The travel distance calculating unit <NUM> calculates, when the motor <NUM> is activated and after the brake block <NUM> is moved to the fully opened position, the travel distance by which the brake block <NUM> travels from the fully opened position to the touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM>. In addition, the travel distance calculating unit <NUM> calculates the travel distance by which the brake block <NUM> travels from the touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM> back to the reference position.

Here, a reference distance L denotes the distance between the center of the wheel <NUM> and the front end of the brake block retainer <NUM>, i.e., the portion where the brake block <NUM> is attached when the brake block retainer <NUM> and the brake block <NUM> are at the reference position. The reference position is the fully opened position where the brake block <NUM> is the farthest away from the wheel <NUM>, i.e., the most retracted position where the brake block retainer <NUM> is retracted the most. The letter "r" denotes the radius of the wheel <NUM>. The letter "A" denotes the thickness of the brake block <NUM>. The letter "B" denotes the travel distance by which the brake block <NUM> travels from the reference position to the touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM>. The letter "C" denotes the wear amount of the brake block <NUM>.

The radius r of the wheel <NUM> is measured when the wheel <NUM> goes through wheel truing and input to the controller device <NUM> as information to be used for speed calculation. Here, the truing of the wheel <NUM> can be classified into preliminary truing and repair truing. The former is conducted every predetermined mileage and the latter is performed if any irregularity such as wheel flat is identified. The change in the radius r of the wheel <NUM> that is found when the wheel truing is conducted is sufficiently less than the wear amount of the brake block <NUM> (the change in the thickness A). This means that the change in the radius r is negligible while the change in the thickness A of the brake block <NUM> is monitored. The strict value of the thickness A of the brake block <NUM> may be obtained by taking into consideration the actually measured value of the radius r of the wheel <NUM> when calculating the thickness A of the brake block <NUM>. For example, the controller device <NUM> includes a target member wear amount acquiring unit <NUM> for acquiring the wear amount of the wheel <NUM>, which is the target member. The wear amount calculating unit <NUM> then uses the acquired wear amount of the wheel <NUM> in calculating the wear amount C of the brake block <NUM>. When a brand-new brake block <NUM> is mounted on the brake block retainer <NUM>, the thickness A of the brake block <NUM> is a uniquely determined value. The travel distance that is measured when the brake block <NUM> is mounted on the brake block retainer <NUM> or when the wheel <NUM> is trued is equivalent to an old value of the travel distance.

The wear amount calculating unit <NUM> calculates the thickness A of the brake block <NUM> according to the following equations (<NUM>) and (<NUM>), and calculates the wear amount C of the brake block <NUM> according to the following equation (<NUM>). The reference distance L is defined as the sum of the radius r of the wheel <NUM>, the thickness A of the brake block <NUM>, and the travel distance B of the brake block <NUM>. Based on these, the thickness A of the brake block <NUM> can be calculated. The wear amount calculating unit <NUM> subtracts the calculated thickness A of the brake block <NUM> from the initial value A0 of the thickness of the brake block <NUM>, thereby calculating the wear amount C of the brake block <NUM>. <MAT> <MAT> <MAT>.

The reference distance L may vary among wheels <NUM> for which the brake device <NUM> is installed. Accordingly, it is desirable to certainly know the initial value of the reference distance L by identifying the radius r, the thickness A, and the travel distance B for each brake device <NUM> immediately after the brake device <NUM> is installed. As the brake block <NUM> wears down, the thickness A of the brake block <NUM> decreases from the initial value A0, and the travel distance B increases. If the newly mounted brake block <NUM> is not a brand-new one, the thickness A of the brake block <NUM> may be stored on the controller device <NUM> as the minimum usable dimension. The wear amount calculating unit <NUM> automatically measures the travel distance B of the brake block <NUM> on the regular basis, for example, during the start-up inspection, daily or weekly inspection, so that the thickness A of the brake block <NUM> is calculated. The wear amount calculating unit <NUM> subtracts the calculated thickness A of the brake block <NUM> from the initial value A0 of the thickness of the brake block <NUM>, thereby calculating the wear amount C of the brake block <NUM>.

The control unit <NUM> compares the wear amount C of the brake block <NUM> against the wear amount C of the brake block <NUM> of any one of the other brake devices <NUM> on the vehicles making up the same train. If the wear amount C of the brake block <NUM> is greater than the wear amount C of the brake block <NUM> of any one of the other brake devices <NUM> making up the same train, the control unit <NUM> adjusts the braking force such that it can be less than the braking force produced by the other brake devices <NUM>.

The brake device <NUM> includes an informing unit <NUM>. The informing unit <NUM> is configured to inform the user of when the wear amount C of the brake block <NUM> becomes equal to or greater than a predetermined value. The informing unit <NUM> is preferably configured to provide such information in a noticeable manner during the start-up inspection, daily or weekly inspection or the like. The informing unit <NUM> can be a speaker outputting sound, a lamp for emitting blinking light, a display unit or the like. The informing unit <NUM> may be alternatively configured to output a signal to the vehicle control console <NUM>.

The following now describes the steps of the procedure performed by the controller device <NUM> to calculate the wear amount, with reference to <FIG> shows the steps of the procedure for calculating, when the motor <NUM> is activated and the brake block <NUM> is moved to the fully opened position, the travel distance B by which the brake block <NUM> travels from the fully opened position to the touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM> and calculating the wear amount C of the brake block <NUM> based on the thickness A of the brake block <NUM>.

To begin with, the controller device <NUM> drives the motor <NUM> to move the brake block <NUM> to the reference position (step S1). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake block <NUM> to the reference position or the fully opened position. The control unit <NUM> knows that the brake block <NUM> has reached the fully opened position by referring to the detection made by the sensor 12A.

Following this, the controller device <NUM> drives the motor <NUM> to move the brake block <NUM> to the touch position (step S2). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake block <NUM> until the brake block <NUM> touches the tread surface 2A of the wheel <NUM>. The control unit <NUM> knows that the brake block <NUM> has reached the touch position by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>, or by using a limit switch or the like.

Subsequently, the controller device <NUM> calculates the travel distance B of the motor <NUM> (step S3). More specifically, the travel distance calculating unit <NUM> calculates the travel distance B by which the brake block <NUM> travels when the brake block <NUM> is moved from the reference position to the touch position in the step S2, based on at least one of the product of the current of the motor <NUM> and the duration or the rotational rate of the motor <NUM>. The step S3 corresponds to a step of calculating a travel distance.

Subsequently, the controller device <NUM> calculates the wear amount C of the brake block <NUM> (step S4). More specifically, the wear amount calculating unit <NUM> calculates the thickness A of the brake block <NUM> according to the equation (<NUM>), using the calculated travel distance B in addition to the radius r of the wheel <NUM> and the reference distance L, which are stored in advance. The wear amount calculating unit <NUM> then subtracts the calculated thickness A of the brake block <NUM> from the initial value A0 of the thickness of the brake block <NUM>, thereby calculating the wear amount C of the brake block <NUM>. The step S4 corresponds to a step of calculating a wear amount. The calculated wear amount C of the brake block <NUM> can determine whether to replace the brake block <NUM>.

The following now describes the steps of the procedure performed by the controller device <NUM> to calculate the wear amount, with reference to <FIG> shows the steps of the procedure for calculating the travel distance B by which the brake block <NUM> travels from the touch position where the brake block <NUM> can touch the tread surface 2A of the wheel <NUM> back to the reference position and calculating the wear amount C of the brake block <NUM> based on the thickness A of the brake block <NUM>.

To begin with, the controller device <NUM> drives the motor <NUM> to move the brake block <NUM> to the touch position (step S11). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake block <NUM> until the brake block <NUM> touches the tread surface 2A of the wheel <NUM>. The control unit <NUM> knows that the brake block <NUM> has reached the touch position by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>, or by using a limit switch or the like.

Following this, the controller device <NUM> drives the motor <NUM> to move the brake block <NUM> to the reference position (step S12). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake block <NUM> to the reference position or the fully opened position. The control unit <NUM> knows that the brake block <NUM> has reached the fully opened position by referring to the detection made by the sensor 12A.

Subsequently, the controller device <NUM> calculates the travel distance B of the brake block <NUM> (step S13). More specifically, the travel distance calculating unit <NUM> calculates the travel distance B of the brake block <NUM> when the brake block <NUM> is moved from the touch position to the reference position in the step S12, based on at least one of the product of the current of the motor <NUM> and the duration or the rotational rate of the motor <NUM>. The step S13 corresponds to a step of calculating a travel distance.

Subsequently, the controller device <NUM> calculates the wear amount C of the brake block <NUM> (step S14). More specifically, the wear amount calculating unit <NUM> calculates the thickness A of the brake block <NUM> according to the equation (<NUM>), using the calculated travel distance B in addition to the radius r of the wheel <NUM> and the reference distance L, which are stored in advance. The wear amount calculating unit <NUM> then subtracts the calculated thickness A of the brake block <NUM> from the initial value A0 of the thickness of the brake block <NUM>, thereby calculating the wear amount C of the brake block <NUM>. The step S14 corresponds to a step of calculating a wear amount. The calculated wear amount C of the brake block <NUM> can determine whether to replace the brake block <NUM>.

Advantageous effects of the first embodiment will be now described.

With reference to <FIG>, the following describes a brake device relating to a second embodiment. Differently from the first embodiment, the brake device relating to the second embodiment 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> rotating integrally with a wheel <NUM> of a railroad 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 produced by the motor <NUM> and also includes a left arm 33A and a right arm 33B. The transmission member <NUM> uses the driving force from the motor <NUM> to displace 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 displaced by the transmission member <NUM> toward side surfaces 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 surfaces 3A of the disc <NUM>. As pressed against the side surfaces 3A of the disc <NUM>, the brake pads 34A and 34B wear out. As a result, the brake pads 34A and 34B becomes 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 a frictional member.

The brake device <NUM> is controlled by a controller device <NUM>, which is configured in the same manner as in the first embodiment. The controller device <NUM> controls the braking force based on a braking command from a vehicle control console <NUM>. The controller device <NUM> includes a control unit <NUM> for controlling the brake device <NUM>. The control unit <NUM> controls driving of the motor <NUM> such that a necessary braking force is produced. The control unit <NUM> controls the driving of the motor <NUM> such that the brake pads 34A and 34B can travel to a position at a predetermined distance from the position where they can touch the side surfaces 3A of the disc <NUM>. In this way, the brake pads 34A and 34B come into contact with the side surfaces 3A of the disc <NUM> and the braking starts working within a constant period of time. The transmission member <NUM> is provided with a sensor 32A for detecting whether the brake pads 34A and 34B are positioned at a reference position for the travel distance of the brake pads 34A and 34B.

The controller device <NUM> includes a driving information acquiring unit <NUM>, a travel distance calculating unit <NUM>, and a wear amount calculating unit <NUM>. The driving information acquiring unit <NUM> is configured to acquire information related to driving of the motor <NUM>. The driving information acquiring unit <NUM> is configured to acquire information detected by the sensor 32A. The travel distance calculating unit <NUM> is configured to calculate the travel distance by which the brake pads 34A and 34B travel to touch the side surfaces 3A of the disc <NUM>. The wear amount calculating unit <NUM> calculates the thickness of the brake pads 34A and 34B based on the currently calculated value of the travel distance and an old value of the travel distance.

The travel distance calculating unit <NUM> calculates the travel distance by which the brake pads 34A and 34B travel from the reference position detected by the sensor 32A to a touch position where the brake pads 34A and 34B can touch the side surface 3A of the disc <NUM>. The reference position is referred to as a fully opened position where the brake pads 34A and 34B are the farthest away from the side surfaces 3A of the disc <NUM>. The travel distance calculating unit <NUM> calculates the travel distance of 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 rotational rate of the motor <NUM>. The control unit <NUM> can know that the brake pads 34A and 34B have reached the touch position where they can touch the side surface 3A of the disc <NUM> by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>. The travel distance calculating unit <NUM> may use a limit switch or the like to detect the touch position.

The travel distance calculating unit <NUM> can calculate the travel distance by which the brake pads 34A and 34B travel in two different ways. The travel distance calculating unit <NUM> calculates, when the motor <NUM> is activated and after the brake pads 34A and 34B are moved to the fully opened position, the travel distance by which the brake pads 34A and 34B travel from the fully opened position to the touch position where the brake pads 34A and 34B can touch the side surface 3A of the disc <NUM>. In addition, the travel distance calculating unit <NUM> calculates the travel distance by which the brake pads 34A and 34B travel from the touch position where the brake pads 34A and 34B can touch the side surfaces 3A of the disc <NUM> back to the reference position.

Here, a reference distance L denotes the distance between the portion of the left arm 33A to which the brake pad 34A is attached and the portion of the right arm 33B to which the brake pad 34B is attached when the left and right arms 33A and 33B and the brake pads 34A and 34B are at the reference position. The reference position is the fully opened position where the brake pads 34A and 34B are the farthest away from the side surface 3A of the disc <NUM>, in other words, where the left and right arms 33A and 33B are the most widely opened. The letter "t" denotes the thickness of the disc <NUM>. The letter "A" denotes the thickness of the brake pads 34A and 34B. The letter "B" denotes the travel distance by which the brake pads 34A and 34B travel from the reference position to the touch position where the brake pads 34A and 34B can touch the side surfaces 3A of the disc <NUM>. The letter "C" denotes the wear amount of the brake pads 34A and 34B.

The thickness t of the disc <NUM> is stored in the controller device <NUM> as initial information. The change in the thickness t of the disc <NUM> is sufficiently less than the wear amount of the brake pads 34A and 34B (the change in the thickness A). This means that the change in the thickness t of the disc <NUM> is negligible while the change in the thickness A of the brake pads 34A and 34B is monitored. When brand-new brake pads 34A and 34B are mounted on the left and right arms 33A and 33B, the thickness A of the brake pads 34A and 34B is a uniquely determined value. The travel distance measured when the brake pads 34A and 34B are mounted on the left and right arms 33A and 33B is referred to as an old value of the travel distance.

The wear amount calculating unit <NUM> calculates the thickness A of the brake pads 34A and 34B according to the following equations (<NUM>) and (<NUM>), and calculates the wear amount C of the brake pads 34A and 34B according to the following equation (<NUM>). The reference distance L is defined as the sum of the thickness t of the disc <NUM>, the thicknesses A of the brake pads 34A and 34B, and the travel distances B of the brake pads 34A and 34B. Based on these, the thickness A of the brake pads 34A and 34B can be calculated. The wear amount calculating unit <NUM> then subtracts the calculated thickness A of the brake pads 34A and 34B from the initial value A0 of the thickness of the brake pads 34A and 34B, thereby calculating the wear amount C of the brake pads 34A and 34B. <MAT> <MAT> <MAT>.

The reference distance L and the thickness t of the disc <NUM> are constant. The wear amount calculating unit <NUM> automatically measures the travel distance B of the brake pads 34A and 34B on the regular basis, for example, during the start-up inspection, daily or weekly inspection, so that the thickness A of the brake pads 34A and 34B is calculated. The wear amount calculating unit <NUM> subtracts the calculated thickness A of the brake pads 34A and 34B from the initial value A0 of the thickness of the brake pads 34A and 34B, thereby calculating the wear amount C of the brake pads 34A and 34B.

The control unit <NUM> compares the wear amount C of the brake pads 34A and 34B against the wear amount C of the brake pads 34A and 34B of any one of the other brake devices <NUM> on the vehicles making up the same train. If the wear amount C of the brake pads 34A and 34B is greater than the wear amount C of the brake pads 34A and 34B of any one of the other brake devices <NUM> making up the same train, the control unit <NUM> adjusts the braking force such that it can be less than the braking force of the other brake devices <NUM>.

The brake device <NUM> includes an informing unit <NUM>. The informing unit <NUM> is configured to issue information when the wear amount C of the brake pads 34A and 34B becomes equal to or greater than a predetermined value. The informing unit <NUM> is preferably configured to provide such information in a noticeable manner during the start-up inspection, daily or weekly inspection or the like. The informing unit <NUM> can be a speaker outputting sound, a lamp for emitting blinking light, a display unit or the like. The informing unit <NUM> may be alternatively configured to output a signal to the vehicle control console <NUM>.

The following now describes the steps of the procedure performed by the controller device <NUM> to calculate the wear amount, with reference to <FIG> shows the steps of the procedure for calculating, when the motor <NUM> is activated and after the brake pads 34A and 34B are moved to the fully opened position, the travel distance B by which the brake pads 34A and 34B travel from the fully opened position to the touch position where the brake pads 34A and 34B can touch the side surfaces 3A of the disc <NUM> and calculating the wear amount C of the brake pads 34A and 34B based on the thickness A of the brake pads 34A and 34B.

To begin with, the controller device <NUM> drives the motor <NUM> to move the brake pads 34A and 34B to the reference position (step S1). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake pads 34A and 34B to the reference position or the fully opened position. The control unit <NUM> knows that the brake pads 34A and 34B have reached the fully opened position by referring to the detection made by the sensor 32A.

Following this, the controller device <NUM> drives the motor <NUM> to move the brake pads 34A and 34B to the touch position (step S2). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake pads 34A and 34B until the brake pads 34A and 34B touch the side surfaces 3A of the disc <NUM>. The control unit <NUM> knows that the brake pads 34A and 34B have reached the touch position by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>, or by using a limit switch or the like.

Subsequently, the controller device <NUM> calculates the travel distance B by the motor <NUM> (step S3). More specifically, the travel distance calculating unit <NUM> calculates the travel distance B of the brake pads 34A and 34B when the brake pads 34A and 34B are moved from the reference position to the touch position in the step S2, based on at least one of the product of the current of the motor <NUM> and the duration or the rotational rate of the motor <NUM>. The step S3 corresponds to a step of calculating a travel distance.

Subsequently, the controller device <NUM> calculates the wear amount C of the brake pads 34A and 34B (step S4). In other words, the wear amount calculating unit <NUM> calculates the thickness A of the brake pads 34A and 34B according to the equation (<NUM>), using the calculated travel distance B in addition to the thickness t of the disc <NUM> and the reference distance L, which are stored in advance. The wear amount calculating unit <NUM> then subtracts the calculated thickness A of the brake pads 34A and 34B from the initial value A0 of the thickness of the brake pads 34A and 34B, thereby calculating the wear amount C of the brake pads 34A and 34B. The step S4 corresponds to a step of calculating a wear amount. The calculated wear amount C of the brake pads 34A and 34B can determine whether to replace the brake pads 34A and 34B.

The following now describes the steps of the procedure performed by the controller device <NUM> to calculate the wear amount, with reference to <FIG> shows the steps of the procedure for calculating the travel distance B by which the brake pads 34A and 34B travel from the touch position where the brake pads 34A and 34B can touch the side surface 3A of the disc <NUM> back to the reference position and calculating the wear amount C of the brake pads 34A and 34B based on the thickness A of the brake pads 34A and 34B.

To begin with, the controller device <NUM> drives the motor <NUM> to move the brake pads 34A and 34B to the touch position (step S11). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake pads 34A and 34B until the brake pads 34A and 34B touch the side surfaces 3A of the disc <NUM>. The control unit <NUM> knows that the brake pads 34A and 34B have reached the touch position by referring to a sudden change in the value of the current flowing through the motor <NUM> or in the rotational rate of the motor <NUM>, or by using a limit switch or the like.

Following this, the controller device <NUM> drives the motor <NUM> to move the brake pads 34A and 34B to the reference position (step S12). More specifically, the control unit <NUM> controls the driving of the motor <NUM> to move the brake pads 34A and 34B to the reference position or the fully opened position. The control unit <NUM> knows that the brake pads 34A and 34B have reached the fully opened position by referring to the detection made by the sensor 32A.

Subsequently, the controller device <NUM> calculates the travel distance B of the brake pads 34A and 34B (step S13). More specifically, the travel distance calculating unit <NUM> calculates the travel distance B of the brake pads 34A and 34B when the brake pads 34A and 34B are moved from the touch position back to the reference position in the step S12, based on at least one of the product of the current of the motor <NUM> and the duration or the rotational rate of the motor <NUM>. The step S13 corresponds to a step of calculating a travel distance.

Subsequently, the controller device <NUM> calculates the wear amount C of the brake pads 34A and 34B (step S14). More specifically, the wear amount calculating unit <NUM> calculates the thickness A of the brake pads 34A and 34B according to the equation (<NUM>), using the calculated travel distance B in addition to the thickness t of the disc <NUM> and the reference distance L, which are stored in advance. The wear amount calculating unit <NUM> then subtracts the calculated thickness A of the brake pads 34A and 34B from the initial value A0 of the thickness of the brake pads 34A and 34B, thereby calculating the wear amount C of the brake pads 34A and 34B. The step S14 corresponds to a step of calculating a wear amount. The calculated wear amount C of the brake pads 34A and 34B can determine whether to replace the brake pads 34A and 34B.

Advantageous effects of the second embodiment will be now described.

The foregoing embodiments can be modified as described below. The above embodiments and the following modifications can be implemented in combination to the extent where they are technically consistent with each other.

In the above-described embodiments, if the wear amount C of the brake pads 34A and 34B is greater than the wear amount C of the brake pads 34A and 34B of any one of the other brake devices <NUM> making up the same train, the braking force is adjusted such that the wear amount of the brake pads 34A and 34B can be leveled among the brake devices <NUM>. However, the braking force may not be adjusted such that the wear amount of the brake pads 34A and 34B is leveled among the brake devices <NUM>.

In the above-described embodiments, the brake devices <NUM> and <NUM> is provided with the informing unit <NUM> for issuing information when the wear amount of the frictional member becomes equal to or greater than a predetermined value. However, the embodiments may be worked without the informing unit <NUM>.

In the above-described embodiments, if the wear amount of the frictional member is greater than the wear amount of the frictional member of any one of the other brake devices, the braking force is adjusted such that it can be less than the braking force of the other brake devices. The wear amount of the frictional member may not be necessarily compared against the wear amount of the frictional member of any one of the other brake devices unless the frictional members need to be replaced around the same time.

In the above-described embodiments, after the frictional member touches the target member to allow the control unit <NUM> to apply braking, the frictional member is moved to and kept stationary at the position where the frictional member is placed at a constant distance from the target member. The present invention is, however, not limited to such. After the frictional member touches the target member to allow the control unit <NUM> to apply braking, the frictional member may be moved back to and kept stationary at the initial position.

In the above-described embodiments, the reference position is the fully opened position, but may be a different position. In other words, after the frictional member is moved to the fully opened position, the travel distance B by which the frictional member travels from the fully opened position to the touch position where the frictional member can touch the target member is calculated. The present invention is, however, not limited to such. After the frictional member is moved to a reference position that is different from the fully opened position, the travel distance B by which the frictional member travels from the reference position to the touch position where the frictional member can touch the target member may be calculated. Alternatively, the travel distance B by which the frictional member travels may be calculated when the frictional member travels from the touch position where the frictional member can touch the target member back to the reference position that is different from the fully opened position.

In the above-described embodiments, the travel distance calculating unit <NUM> calculates the travel distance B of the frictional member in two different ways. The travel distance calculating unit <NUM> may be, however, configured to calculate the travel distance B of the frictional member in only one way.

In the above-described embodiments, the frictional member is displaced using the rotating motors <NUM> and <NUM>, but the frictional member may be displaced using a linearly moving actuator and a linear actuator. In the above-described embodiments, the wear amount C of the frictional member is referred to in order to determine whether to replace the frictional member, but the thickness A of the frictional member may be alternatively referred to in order to determine whether to replace the frictional member. For example, it is determined to replace the frictional member if the thickness A of the frictional member becomes equal to or less than a predetermined value.

The foregoing embodiments describe a plurality of physically separate constituent parts. They may be combined into a single part, and any one of them may be divided into a plurality of physically separate constituent parts. Irrespective of whether or not the constituent parts are integrated, they are acceptable as long as they are configured to solve the problems.

Claim 1:
A brake device (<NUM>, <NUM>) for applying a brake to a vehicle provided with a target member (<NUM>, <NUM>) by using an electric actuator (<NUM>, <NUM>) to drive a frictional member (<NUM>, 34A, 34B) so that the frictional member (<NUM>, 34A, 34B) is pressed against the target member (<NUM>, <NUM>), the brake device (<NUM>, <NUM>) comprising:
an acquiring unit (<NUM>) for acquiring driving information regarding driving of the electric actuator (<NUM>, <NUM>);
a travel distance calculating unit (<NUM>) for, based on the acquired driving information, calculating a travel distance by which the frictional member (<NUM>, 34A, 34B) travels to touch the target member (<NUM>, <NUM>);
a wear amount calculating unit (<NUM>) for calculating a wear amount (C) of the frictional member (<NUM>, 34A, 34B) based on a currently calculated value of the travel distance and an old value of the travel distance, and
a control unit (<NUM>) for controlling driving of the electric actuator (<NUM>, <NUM>),
wherein the control unit (<NUM>) controls the driving of the electric actuator (<NUM>, <NUM>) such that the frictional member (<NUM>, 34A, 34B) travels to a position that is at a predetermined distance from the position where the frictional member (<NUM>, 34A, 34B) touches the target member (<NUM>, <NUM>), and
characterized in that,
when the wear amount (C) of the frictional member (<NUM>, 34A, 34B) is greater than a wear amount (C) of a frictional member of another brake device provided on another vehicle making up a same train, the control unit (<NUM>) adjusts a braking force such that the braking force is less than a braking force of the other brake device.