Patent Description:
An intersection where a railway line crosses a road or path is referred to as a level crossing. Level crossings utilize gate crossing mechanisms to control traffic on the road or path when a train or other vehicle is passing through the level crossing. The gate crossing mechanisms prevent vehicles, pedestrians, etc., from crossing the railway line while the gate crossing mechanism is engaged.

<CIT> relates to a control circuit for an automobile window motor.

<CIT> relates to a gate mechanism to rotate a gate arm of a highway grade crossing gate system.

Embodiments of the present invention are directed to direction control for a motor of a gate crossing mechanism.

An example method includes includes providing, by a field-effect transducer (FET) driver, a first voltage via a high output to a normally open contact of a first relay and to a normally closed contact of a second relay. The first voltage causes a shaft of the motor to turn in a first direction. The method further includes providing, by the FET driver, a second voltage via a low output to a normally closed contact of the first relay and to a normally open contact of the second relay. The second voltage causes the shaft of the motor to turn in a second direction opposite the first direction.

An example gate crossing mechanism includes a motor having a first phase, a second phase, and a third phase. The gate crossing mechanism further includes a first relay circuit associated with the first phase. The first relay circuit selectively provides, by a first field-effect transducer (FET) driver, a first voltage via a high output to a normally open contact of a first relay and to a normally closed contact of a second relay or a second voltage via a low output to a normally closed contact of the first relay and to a normally open contact of the second relay. The gate crossing mechanism further includes a second relay circuit associated with the second phase. The second relay circuit selectively provides, by a second FET driver, the first voltage via a high output to a normally open contact of a third relay and to a normally closed contact of a fourth relay or the second voltage via a low output to a normally closed contact of the third relay and to a normally open contact of the fourth relay. The gate crossing mechanism further includes a third relay circuit associated with the third phase. The third relay circuit selectively provides, by a third FET driver, the first voltage via a high output to a normally open contact of a fifth relay and to a normally closed contact of a sixth relay or the second voltage via a low output to a normally closed contact of the fifth relay and to a normally open contact of the sixth relay.

Other examples implement features of the above-described method in computer systems and computer program products.

Embodiments and aspects of the invention are described in detail herein.

The diagrams depicted herein are illustrative. There can be many variations to the diagram or the operations described therein without departing from the scope of the invention. For instance, the actions can be performed in a differing order or actions can be added, deleted or modified. Also, the term "coupled" and variations thereof describes having a communications path between two elements and does not imply a direct connection between the elements with no intervening elements/connections between them. All of these variations are considered a part of the specification.

One or more embodiments of the present invention provide for a gate crossing mechanism, including techniques for controlling a gate crossing motor and/or detecting and/or preventing faults of the gate crossing motor. A gate crossing mechanism protects motorists, pedestrians, and the like from oncoming trains by blocking level crossings or points at which public or private roads cross railway lines at the same level.

As one example, a gate crossing mechanism can include an arm or "gate" that, using a motor, selectively lowers/raises depending upon whether a train or other vehicle is passing through the level crossing. For example, if a train is approaching a level crossing, a gate can be lowered to prevent traffic on the road or path from crossing the railway line. A level crossing can be equipped with multiple gate crossing mechanisms. For example, each side of the railway line can include a gate crossing mechanism. In larger intersections, each side of the railway line can include two (or more) gate crossing mechanisms. Gate crossing mechanisms can further include lights, sirens, bells, or other similar devices that can provide visual and/or aural warnings.

Conventional gate crossing mechanisms can be susceptible to failures, malfunctions, etc., which can reduce their ability to control a level crossing safely. It is, therefore, desirable to improve efficiency, reliability, and functionality of conventional gate crossing mechanisms.

The above-described aspects of the invention address the shortcomings of the prior art by providing techniques for improving the efficiency, reliability, and functionality of gate crossing mechanisms. Such aspects can include fault detection of a gate crossing motor, overspeed protection of a gate crossing motor, direction control of a gate crossing motor, and thermal lockout of a gate crossing motor.

Gate crossing mechanisms having the features and functionality described herein provide improve efficiency and address problems associated with conventional gate crossing mechanisms. For example, a gate crossing mechanism can include a brushless motor and digital control logic rather than a conventional brushed motor and mechanical cams. Motor brushes can experience uneven wear patterns, after which they must be replaced. This is both costly and time consuming for railways or those responsible for maintaining gate crossing mechanisms featuring brushed motors. Moreover, whereas conventional gate crossing mechanisms having brushed motors required more than two cams, the brushless motors of the gate crossing mechanisms described herein can use substantially less cams (e.g., two cams).

Additionally, the brushless motors of the gate crossing mechanisms described herein provide expanded fault detection such as overcurrent and overtemperature detection, which can be determined from measured three-phase motor currents. This active fault detection serves to increase the availability of the gate crossing mechanism. The brushless motors of the gate crossing mechanisms described herein also provide an improved user interface to give maintainers clear feedback on gate configuration. This improves efficiency and accuracy for maintainers to set gate attributes in the field, thereby decreasing human error. Finally, the brushless motors of the gate crossing mechanisms described herein support a configurable gate that can function as either an entrance or an exit gate, which can depend for example the FPGA firmware. This is a stark difference from the conventional gate crossing mechanisms, which can only function as an entrance gate unless an additional logic card is attached.

Turning now to <FIG>, a block diagram of a controller <NUM> for a motor <NUM> of a gate crossing mechanism <NUM> is depicted according to one or more embodiments described herein. In this example, the gate crossing mechanism <NUM> includes the motor <NUM>, the controller <NUM>, and a gate <NUM>. The gate <NUM> can be supported by any suitable structure, such as a gate support <NUM>. The controller <NUM> and/or the motor <NUM> can be coupled to, incorporated in, or otherwise associated with the gate <NUM> and/or the gate support <NUM>. The gate crossing mechanism <NUM> controls the gate <NUM> at a crossing <NUM> of a railway <NUM> and a road <NUM>. The gate <NUM>, when in a "down" or "closed" position, prevents traffic traveling along the road <NUM> from crossing the intersection <NUM>. In examples, the intersection can be controlled by additional gate crossing mechanisms (not shown).

<FIG> depicts a block diagram of the controller <NUM> of <FIG> being configured for direction control for the motor <NUM> of <FIG> according to one or more embodiments described herein. According to one or more embodiments described herein, the controller <NUM> can include various components configured and arranged as shown.

As one example, the controller <NUM> includes a processor <NUM>, a field-programmable gate array (FPGA) <NUM>, a signal isolation block <NUM>, a charge pump <NUM>, and a three-phase inverter <NUM>. In some examples, the processor <NUM> includes an analog-to-digital converter (ADC). As shown in <FIG>, one or more of the processor <NUM>, the FPGA <NUM>, the charge pump <NUM>, and/or the three-phase inverter <NUM> can be powered by a battery <NUM>, although any suitable power source can be used. The three-phase inverter <NUM> drives the motor <NUM> via relay circuits 220A, 220B, 220C for the respective three phases of the motor (e.g., phase A, phase B, phase C).

Conventional motors used in gate crossing mechanisms, such as the gate crossing mechanism <NUM>, rely on software (executed, for example, by a processor or field-programmable gate array) to control the direction of the motor <NUM>. In some error states or fault conditions, the software may not be able to execute. For example, if the processor or FPGA experiences a failure, the software may be unable to control the direction of the motor <NUM>. Accordingly, to provide a more reliable motor, the present techniques provide a hardware-based approach to direction control of a brushless motor (e.g., the motor <NUM>) for a gate crossing mechanism (e.g., the gate crossing mechanism <NUM>).

In particular, according to one or more embodiments described herein, the motor <NUM> can easily and reliably switch directions by using hardware-based relays. To switch directions in the motor <NUM>, the current in coils of the motor <NUM> is switched. As an example, consider the motor <NUM> being a three-phased brushless motor having a phase A, phase B, and phase C. In such an example, hardware-based relays are used to switch the motor direction. If phase A is being driven on the high side (e.g., <NUM> volts) and phase B is grounded (e.g., <NUM> volts), then a shaft (not shown) of the motor <NUM> is rotating in one direction (e. g, clockwise). If the phases are flipped such that phase B is being driven on the high side (e.g., <NUM> volts) and phase A is grounded (e.g., <NUM> volts), then the current is reversed in the coils of the motor <NUM> and the shaft of the motor <NUM> switches to rotating in the other direction (e.g., counterclockwise). To do this, a relay is added to each phase of the motor <NUM>. For each phase, a normally closed position of the relay and a normally open position of the relay are tied to the high sides and the low sides inversely of each other so that if the relay is sitting normally. For example, if it is desired for the gate <NUM> to come down in the normally closed contact position of the relay, the high side and the low side gates are set up so that the motor <NUM> would drive the gate <NUM> and it would come down. If the relay is energized, the relay flips, on each phase, the high side and the low side, essentially reversing the current in the coils of the motor <NUM>, thus reversing the direction of the motor <NUM>.

According to one or more embodiments described herein, software in the FPGA <NUM> is configured for one direction of motor rotation. The commutation software is only configured to run the FPGA <NUM> in a safe direction (e.g., downward for entrance gates and upward for exit gates). The relay circuits 220A, 220B, 220C utilize 3x1 form C relays to control the direction of the motor. Two relays are needed per phase of the motor where each phase is driven through a high and a low side FET driver (e.g., the FET driver U3 of <FIG>). For each phase, the high side FET gate is connected to the common connection of a first relay while the low side gate signal is connected to a normally open contact of the first relay and the high side gate signal is connected to the normally closed relay contact of the first relay. For each phase, the low side FET gate is connected to the common connection of a second relay while the low side gate signal is connected to the normally closed contact of the second relay and the high side gate driver signal is connected to the normally open contact of the second relay. The power source for the relay is the power from an isolated gate control (GC) signal received from the controller <NUM> (e.g., from the three-phase inverter <NUM>) as inputs to the FET gate (see, e.g., inputs <NUM>, <NUM> of <FIG>). When the GC is high, the contacts will flip the high and low side gate signals effectively changing the direction of rotation of a shaft of the motor <NUM>. For example, this could be an upward direction for the gate <NUM> if the gate crossing mechanism <NUM> is an entrance gate and downward for the gate <NUM> if the gate crossing mechanism <NUM> is an exit gate. If the GC is low then the commutation can only happen in a safe direction. The relay can be of a standard electromechanical relay or a solid-state relay and can be placed before or after the FET driver chip. In an example in which the relay is placed before the FET driver, a smaller load relay could be used (e.g., less than <NUM> milliamps) whereas placing the relay after the FET driver would use a larger size relay (e.g., about <NUM> amp).

<FIG> and <FIG> depict the relay circuit 220A of <FIG> for controlling a direction of rotation of a shaft of the motor <NUM> of <FIG> according to one or more embodiments described herein. Although the relay circuit 220A is shown, it should be appreciated that the relay circuits 220B, 220C are substantially similar to the relay circuit 220A and are not shown for brevity.

The shaft (not shown) of the motor <NUM> can rotate in two different directions (e.g., clockwise and counterclockwise).

A field-effect transducer (FET) driver U3 takes as inputs logic level voltages and boosts those voltages to higher current to turn on MOSFITS U1, U2. In particular, the FET driver U3 receives inputs <NUM>, <NUM> from the three-phase inverter <NUM> of <FIG>. The input <NUM> is a high input signal, and the input <NUM> is a low input signal. The FET driver U3 also selectively drives relays as shown in <FIG>. In particular, the circuit <NUM> includes two relays K4, K8 (see <FIG>). The high output (pin <NUM>) of the FET driver U3 is connected to the normally open contact (pin <NUM>) of the relay K4 and the normally closed contact (pin <NUM>) of the relay K8. Inversely, the low output (pin <NUM>) of the FET driver U3 is connected to the normally closed contact (pin <NUM>) of the relay K4 and the normally open contact (pin <NUM>) of the relay K8.

When the FET driver U3 is selectively driving on the high output (pin <NUM>), current flows through the normally open contact (pin <NUM>) of the relay K4 and the normally closed contact (pin <NUM>) of the relay K8. When the FET driver U3 switches from driving on the high output (pin <NUM>) to driving on the low output (pin <NUM>), current flows through the normally closed contact (pin <NUM>) of the relay K4 and the normally open contact (pin <NUM>) of the relay K8, thereby switching directions of the current flow. Thus, the direction of rotation of a shaft of the motor <NUM> can be controlled by the FET driver U3 using the relays K4, K8 on phase A of the motor <NUM>. Similar circuits to the circuit <NUM> can be applied to the other phases (i.e., phase B and phase C as shown in <FIG>) of the motor <NUM> to control the direction of rotation of the shaft of the motor <NUM>. In examples, one or more of the relays K4, K8 can be vital relays, which increases reliability versus using non-vital relays. One or more of the relays K4, K8 can be solid-state relays or electromechanical relays.

The embodiments described herein may be implemented as one or more systems, methods, and/or computer program products at any possible technical detail level of integration.

Various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and/or positional relationships, unless specified otherwise, can be direct or indirect, and the present invention is not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship. Moreover, the various tasks and process steps described herein can be incorporated into a more comprehensive procedure or process having additional steps or functionality not described in detail herein.

Additionally, the term "exemplary" is used herein to mean "serving as an example, instance or illustration. " Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "at least one" and "one or more" may be understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms "a plurality" may be understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc. The term "connection" may include both an indirect "connection" and a direct "connection.

For the sake of brevity, conventional techniques related to making and using aspects of the invention may or may not be described in detail herein. In particular, various aspects of computing systems and specific computer programs to implement the various technical features described herein are well known. Accordingly, in the interest of brevity, many conventional implementation details are only mentioned briefly herein or are omitted entirely without providing the well-known system and/or process details.

The descriptions of the various embodiments of the present invention have been presented for purposes of illustration but are not intended to be exhaustive or limited to the embodiments disclosed.

Claim 1:
A method for direction control of a shaft of a motor (<NUM>) of a gate crossing mechanism (<NUM>), the method comprising:
providing a motor (<NUM>);
providing a controller (<NUM>) which is configured to drive the motor (<NUM>) via at least one relay circuit (220A);
selectively providing, by a field-effect transducer (FET) driver (U3), a first voltage via a high side gate of the FET drive (U3) to a normally open contact of a first relay (K4) of the relay circuit (220A) and to a normally closed contact of a second relay (K8) of the relay circuit (220A), the first voltage causing a shaft of the motor (<NUM>) to turn in a first direction; or
selectively providing, by the FET driver (U3), a second voltage via a low side gate of the FET driver (U3) to a normally closed contact of the first relay (K4) and to a normally open contact of the second relay (K8), the second voltage causing the shaft of the motor (<NUM>) to turn in a second direction opposite the first direction.