RELAY SYSTEM

A relay system includes a relay device and a controller. The relay device includes a contact and a driving mechanism configured to switch the contact between an open mode and a closed mode. The controller is configured to control the relay device. The controller is configured to, when freezing occurs on the contact, to commence first application of electric current to the driving mechanism to generate a driving force acting in a direction in which the contact is not switched between the open mode and a closed mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2022-154305 filed on Sep. 28, 2022, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The disclosure relates to relay systems.

Japanese Unexamined Patent Application Publication No. 2011-210385 discloses a relay controller that prevents a contact of a relay device from freezing. The relay controller switches the relay device to an open mode by stopping the application of electric current to a coil, and then continuously applies electric current to the coil to an extent that the relay device does not switch to a closed mode, thereby preventing condensation and freezing from occurring on the contact.

SUMMARY

An aspect of the disclosure provides a relay system including a relay device and a controller. The relay device includes a contact and a driving mechanism configured to switch the contact between an open mode and a closed mode. The controller is configured to control the relay device. The controller is configured to, when freezing occurs on the contact, commence first application of electric current to the driving mechanism to generate a driving force acting in a direction in which the contact is not switched between the open mode and the closed mode.

An aspect of the disclosure provides a relay system including a relay device and circuitry. The relay device includes a contact, and a driving mechanism including coil and configured to switch the contact between an open mode and a closed mode. The circuitry is configured to control the relay device. The circuitry is configured to, when freezing occurs on the contact, commence first application of electric current to the coil of the driving mechanism to generate a driving force acting in a direction in which the contact is not switched between the open mode and the closed mode.

DETAILED DESCRIPTION

In the relay controller in the related art, since the contact is heated by applying electric current to the coil to an extent that the relay device does not switch between the open and closed modes, it is difficult to apply a large amount of heat to the contact at once. Therefore, in this method, when freezing occurs on the contact, it takes a long period of time until the contact becomes usable again by unfreezing. Assuming that the unfreezing process is performed by applying a large amount of electric current to the coil to an extent that the relay device switches between the open and closed modes, the contact undesirably switches between the open and closed modes when the unfreezing process is completed. This results in limitations on the unfreezing timing, and also shortens the lifespan of the contact.

It is desirable to provide a relay system that suppresses a reduced lifespan of a contact and that can quickly deal with freezing occurring on the contact when such freezing occurs.

The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the specification, serve to describe the principles of the disclosure.

FIG.1illustrates the configuration of a relay device according to the embodiment of the disclosure.FIG.1is a vertical sectional view of a relay device10, taken along a stationary core163.

The relay device10according to this embodiment is a latching relay. A latching relay is to be supplied with electric current when contacts A11and A12are to be switched from an open mode to a closed mode and when the contacts A11and A12are to be switched from the closed mode to the open mode. In addition, after the switching to the open or closed mode, the latching relay maintains the open or closed mode even when the application of the electric current is discontinued.

As illustrated inFIG.1, the relay device10includes the pair of contacts A11and A12switchable between a separated state and a contact state, first and second terminals (not illustrated) by which one of electric circuits to be opened and closed is coupled to the other one of the electric circuits, a first conductor11that electrically couples the contact A11and the first terminal to each other, and a second conductor12that electrically couples the contact A12and the second terminal to each other. The contact A11is fixed to a part of the first conductor11, and the contact A12is fixed to a part of the second conductor12. A part of the second conductor12is supported in a displaceable manner by a spring member165. This displacement causes the pair of contacts A11and A12to switch between the separated state and the contact state.

The relay device10further includes a driving mechanism16that moves the pair of contacts A11and A12toward or away from each other, a housing19, and a first temperature sensor18that detects the temperature inside the housing19.

The driving mechanism16includes a first coil161, a second coil162, the stationary core163, a movable core164, the spring member165, and a latching mechanism (not illustrated). By being supplied with electric current, the first coil161and the second coil162generates a driving force (magnetic force) that moves the movable core164between the stationary core163and the movable core164. By being supplied with electric current, the first coil161generates a driving force in a direction for bringing the contacts A11and A12adjacent to each other. By being supplied with electric current, the second coil162generates a driving force in a direction for separating the contacts A11and A12from each other. The aforementioned direction for bringing the contacts A11and A12adjacent to each other refers to a direction for switching the contacts A11and A12from the open mode to the closed mode. The aforementioned direction for separating the contacts A11and A12from each other refers to a direction for switching the contacts A11and A12from the closed mode to the open mode. The first coil161may be referred to as closed excitation wiring. The second coil162may be referred to as open excitation wiring. The latching mechanism maintains the movable core164at two positions, that is, a position where the contacts A11and A12are in contact with each other and a position where the contacts A11and A12are separated from each other.

A terminal of the first coil161and a terminal of the second coil162are disposed outside the housing19. Electric current can be applied to the first coil161and the second coil162via an external terminal.

The first temperature sensor18has a detector disposed inside the housing19and outputs a detection signal indicating a detected temperature to the outside of the housing19. The first temperature sensor18may be fixed to, for example, the housing19. The temperature detected by the first temperature sensor18is, for example, the temperature of air inside the housing19. Alternatively, the temperature detected by the first temperature sensor18may be the temperature of the first conductor11to which the contact A11is fixed or the temperature of the second conductor12to which the contact A12is fixed.

The housing19accommodates the pair of contacts A11and A12, the first conductor11, the second conductor12, and the driving mechanism16. The housing19may be internally sealed. The terminal (first terminal) of the first conductor11, the terminal (second terminal) of the second conductor12, the terminal of the first coil161, and the terminal of the second coil162are provided outside the housing19.

In the relay device10having the above-described configuration, when the first coil161is supplied with electric current in a state where the pair of contacts A11and A12are separated from each other, the movable core164and a movable part of the second conductor12receive a driving force acting in the direction for bringing the pair of contacts A11and A12adjacent to each other. Then, the movable core164and the movable part of the second conductor12move to bring the contacts A11and A12into contact with each other, whereby the relay device10switches to the closed mode. In this case, the latching mechanism maintains the movable core164and the movable part of the second conductor12in position. Subsequently, the relay device10is maintained in the closed mode even when the application of the electric current to the first coil161is discontinued.

When the second coil162is supplied with electric current in a state where the pair of contacts A11and A12are near each other, the movable core164and the movable part of the second conductor12receive a driving force acting in the direction for separating the pair of contacts A11and A12from each other. Then, the movable core164and the movable part of the second conductor12move to separate the contacts A11and A12from each other, whereby the relay device10switches to the open mode. In this case, the latching mechanism maintains the movable core164and the movable part of the second conductor12in position. Subsequently, the relay device10is maintained in the open mode even when the application of the electric current to the second coil162is discontinued.

Relay System

FIG.2illustrates a relay system and a power supply device according to an embodiment of the disclosure. A relay system100according to this embodiment includes the relay device10, a controller20that controls the relay device10, and a second temperature sensor30that detects the ambient temperature.

The relay system100may be applied to a power supply device220of a vehicle200, such as an electric vehicle (EV), a hybrid electric vehicle (HEV), or an engine vehicle. The power supply device220includes an electric power supplier221, such as a battery, a DC/DC converter, or a power generator, an electric power line222that delivers electric power from the electric power supplier221to an electric device224, and the relay device10that opens and closes an electric circuit of the electric power line222.

The relay device10may be disposed in a power source room, such as an engine room. During the cold season, the power source room may increase in temperature due to driving of a power source, and may rapidly decrease in temperature due to a stoppage of the power source. Moreover, the power source room may be in a harsh temperature environment when the temperature decreases below the freezing point due to a long stoppage of the power source. As time passes, the relay device10disposed in the harsh temperature environment may internally receive moisture even if the relay device10is internally sealed by the housing19. When moisture enters the relay device10, the moisture in the relay device10vaporizes as the relay device10increases in temperature. Then, heat is extracted from within the relay device10via the electric power line222having a large heat capacity, so that the first conductor11and the second conductor12decrease in temperature first, possibly causing condensation to occur in the contacts A11and A12. Then, when the temperature decreases below the freezing point, freezing occurs on the contacts A11and A12.

The second temperature sensor30is configured to detect an outside air temperature of the vehicle200as an ambient temperature. Alternatively, the second temperature sensor30may be configured to detect an air temperature in the space (e.g., the power source room) where the relay device10is disposed. The second temperature sensor30transmits a detection signal indicating the detected temperature to the controller20.

The controller20is an electronic control unit (ECU), has a storage unit22storing a control program, and controls the relay device10in accordance with the control program. The controller20may communicate with a second ECU, such as a controller of the vehicle200, and perform control for switching the relay device10between the open and closed modes based on a request from the second ECU. Furthermore, the controller20may be integrated with the second ECU, such as the controller of the vehicle200.

The function of the controller20will now be described. The controller20has a function for switching the relay device10between the open and closed modes based on a request for switching the relay device10between the open and closed modes. The switching between the open and closed modes is performed by applying electric current to the first coil161or the second coil162.

The controller20further has a function for performing an estimation related to whether freezing has occurred on the contacts A11and A12based on a temperature detected by the first temperature sensor18and a temperature detected by the second temperature sensor30. The estimation related to whether freezing has occurred includes estimating whether freezing has occurred, estimating a possibility of freezing, and estimating whether the possibility has exceeded a certain threshold value. The following description relates to a case where the first temperature sensor18detects the air temperature inside the housing19and the second temperature sensor30detects the outside air temperature. The outside air temperature detected by the second temperature sensor30is readily transmitted as the temperature of the contacts A11and A12via the electric power line222. Therefore, based on a difference between the temperature detected by the first temperature sensor18and the temperature detected by the second temperature sensor30, the controller20can estimate a possibility of condensation occurring as a result of vaporized moisture within the housing19condensing on the contacts A11and A12. This estimation is possible by preliminarily creating, by simulation or test, a data table in which the aforementioned temperature difference, the detected temperature values, and the value indicating the possibility of condensation are associated with one another, and providing the data table to the controller20. Furthermore, when the controller20estimates that condensation has occurred and the temperatures detected by the first temperature sensor18and the second temperature sensor30are temperatures that cause the condensation to freeze, the controller20can estimate that there is a possibility that freezing has occurred on the contacts A11and A12.

The temperatures detected by the first temperature sensor18and the second temperature sensor30are not limited to the above examples. The following description relates to a case where the first temperature sensor18detects the temperature of the first conductor11or the second conductor12in the housing19, and the second temperature sensor30detects the air temperature in the power source room. The air temperature detected by the second temperature sensor30in the power source room is close to the air temperature in the housing19. Therefore, based on a difference between the temperature detected by the first temperature sensor18and the temperature detected by the second temperature sensor30, the controller20can estimate a possibility of condensation occurring as a result of vaporized moisture within the housing19condensing on the contacts A11and A12. If there is a possibility of condensation and the temperatures detected by the first temperature sensor18and the second temperature sensor30are temperatures that cause the condensation to freeze, the controller20can estimate that there is a possibility that freezing has occurred on the contacts A11and A12.

If the relay device10is not switched between the open and closed modes regardless of the fact that the controller20has performed control for switching the relay device10between the open and closed modes, the controller20may estimate that freezing has occurred on the contacts A11and A12. The determination of whether the relay device10is switched between the open and closed modes can be performed based on detection values of, for example, voltage and electric current of the electric power line222. In addition to the above-described case, the controller20may perform the estimation related to whether freezing has occurred on the contacts A11and A12based on additional information indicating whether the temperature detected by the first temperature sensor18or the second temperature sensor30is a temperature that causes freezing to occur.

The controller20further has a function for dealing with freezing by performing first application of electric current to the driving mechanism16(i.e., application of electric current to the first coil161and the second coil162) if the controller20estimates that the freezing has occurred on the contacts A11and A12. The first application of electric current involves applying electric current to the driving mechanism16to generate a driving force in a direction in which the contacts A11and A12are not switched between the open and closed modes. With the first application of electric current, a relatively large amount of electric current can be applied without switching the contacts A11and A12between the open and closed modes, thereby generating a large amount of heat (Joule's heat) in the driving mechanism16. Consequently, by heating the contacts A11and A12using the generated heat, unfreezing can be performed quickly.

In one example, when the contacts A11and A12are in the open mode, the first application of electric current corresponds to application of electric current to the second coil162to generate a driving force in the direction for separating the contacts A11and A12from each other. When the contacts A11and A12are in the closed mode, the first application of electric current corresponds to application of electric current to the first coil161to generate a driving force in the direction for bringing the contacts A11and A12adjacent to each other. The first application of electric current may involve applying electric current concurrently to the first coil161and the second coil162. In this case, driving forces acting in the direction for separating the contacts A11and A12from each other and in direction for bringing the contacts A11and A12adjacent to each other are both generated in the driving mechanism16. In one example, when the contacts A11and A12are in the open mode, a driving force acting in a direction for not switching between the open and closed modes (i.e., in the direction for separating the contacts A11and A12from each other) is generated. When the contacts A11and A12are in the closed mode, a driving force acting in a direction for not switching between the open and closed modes (i.e., in the direction for bringing the contacts A11and A12adjacent to each other) is generated. Therefore, the contacts A11and A12are not switched between the open and closed modes even when a large amount of electric current is applied thereto. If there is provided a drive circuit capable of applying electric current in the reverse direction to the first coil161or the second coil162, the controller20may perform the first application of electric current involving applying electric current in the reverse direction to generate a driving force in the direction for not switching between the open and closed modes.

The following description relates to an unfreezing process executed by the controller20.FIG.3is a flowchart illustrating the unfreezing process executed by the controller20. The unfreezing process may be executed constantly while the controller20is in operation, or may be executed while the controller20is in operation during the cold season in which freezing may occur. Alternatively, if the timing at which the relay device10switches between the open and closed modes is predictable, the unfreezing process may be executed immediately before this timing. For example, if the relay device10is configured to switch to the closed mode immediately upon system activation of the vehicle200, the controller20may execute the unfreezing process during a period from when the system is activated to when the relay device10switches to the closed mode. As another alternative, if there is a high possibility in which the relay device10may switch to the closed mode at the time of reactivation after an idling-stop mode of the engine, the controller20may execute the unfreezing process during the period from the idling-stop mode to the reactivation of the engine.

When the unfreezing process commences, the controller20acquires temperatures detected by the first temperature sensor18and the second temperature sensor30in step S1, and estimates a possibility of freezing occurring on the contacts A11and A12based on these detected temperatures in step S2. Then, the controller20determines whether there is a possibility of freezing in step S3. If there is no possibility, the controller20repeats the process from step S1to step S3.

In contrast, if the controller20determines that there is a possibility of freezing, the controller20determines whether the relay device10is in the open or closed mode in step S4. If the relay device10is in the open mode, the controller20starts to apply electric current to the second coil (open excitation wiring)162in step S5to generate a driving force in the direction for switching to the open mode. Subsequently, the controller20determines whether the temperature detected by the first temperature sensor18has exceeded a threshold value in step S6. If the determination result indicates “NO”, the controller20repeats the determination process in step S6. The threshold value is set to a value that enables unfreezing. When the determination result obtained in step S6indicates “YES”, the controller20starts to perform a timekeeping process and determines in step S7whether a time period in which the temperature has exceeded the threshold value is longer than or equal to a set time period. If the obtained result indicates “NO”, the controller20returns to step S6.

When the controller20determines in step S6that the detected temperature is greater than or equal to the threshold value and determines in step S7that the time period in which the temperature is greater than or equal to the threshold value is longer than or equal to the set time period, the controller20terminates the application of electric current in step S11. Even when freezing has occurred on the contacts A11and A12as result of step S6and step S7, it can be determined quickly with high accuracy that unfreezing has been completed using the heat of the second coil162.

In contrast, if the determination result obtained in step S4indicates that the relay device10is in the closed mode, the controller20starts to apply electric current to the first coil (closed excitation wiring)161in step S8to generate a driving force in the direction for switching to the closed mode. Subsequently, the controller20determines whether the temperature detected by the first temperature sensor18has exceeded a threshold value in step S9. If the determination result indicates “NO”, the controller20repeats the determination process in step S9. The threshold value is set to a value that enables unfreezing. When the determination result obtained in step S9indicates “YES”, the controller20starts to perform a timekeeping process and determines in step S10whether a time period in which the temperature has exceeded the threshold value is longer than or equal to a set time period. If the obtained result indicates “NO”, the controller20returns to step S9.

When the controller20determines in step S9that the detected temperature is greater than or equal to the threshold value and determines in step S10that the time period in which the temperature is greater than or equal to the threshold value is longer than or equal to the set time period, the controller20terminates the application of electric current in step S11. Even when freezing has occurred on the contacts A11and A12as result of step S9and step S10, it can be determined quickly with high accuracy that unfreezing has been completed using the heat of the first coil161.

When the application of electric current is completed in step S11, the controller20ends the unfreezing process. Alternatively, if the unfreezing process is to be executed continuously for a certain time period, the controller20repeatedly executes the above-described unfreezing process until the aforementioned time period elapses.

A program of the above-described unfreezing process is stored in a non-transitory computer readable medium, such as the storage unit22of the controller20. The controller20may be configured to read a program stored in a portable non-transitory computer readable medium and execute the program. The aforementioned portable non-transitory computer readable medium may store the program of the above-described unfreezing process.

Accordingly, in the relay system100according to this embodiment, when the controller20estimates that there is a possibility of freezing occurring on the contacts A11and A12of the relay device10, the controller20commences first application of electric current to the driving mechanism16. The first application of electric current involves applying electric current to the driving mechanism16to generate a driving force in the direction in which the contacts A11and A12are not switched between the open and closed modes. Thus, the first application of electric current can be performed with a relatively large amount of electric current. With the first application of electric current, a large amount of heat can be generated from the driving mechanism16. Consequently, unfreezing can be performed quickly on the contacts A11and A12. Furthermore, even when a large amount of electric current is applied, a driving force acting in the direction for not switching between the open and closed modes is generated in the driving mechanism16, so that the contacts A11and A12are not switched between the open and closed modes when the unfreezing of the contacts A11and A12is completed. Accordingly, the unfreezing timing is less likely to be limited, and a reduced lifespan of the contacts A11and A12can be suppressed.

As an alternative to the above embodiment in which the controller20is configured to perform the freezing-related estimation and execute the first application of electric current, the controller20may be configured to not perform the freezing-related estimation. For example, when freezing occurs, a request for the first application of electric current may be transmitted to the controller20from an external source, and the controller20may be configured to commence the first application of electric current based on the request.

The relay system100according to this embodiment further includes the first temperature sensor18that detects the temperature inside the housing19, and the controller20terminates the first application of electric current based on the temperature detected by the first temperature sensor18. Accordingly, with the first application of electric current, the reliability of the unfreezing process performed on the contacts A11and A12can be enhanced.

The relay system100according to this embodiment further includes the second temperature sensor30that detects the ambient temperature. The controller20performs the estimation related to whether freezing has occurred on the contacts A11and A12based on the temperature detected by the first temperature sensor18and the temperature detected by the second temperature sensor30. Normally, condensation occurs before freezing, and occurs mainly due to a temperature difference between the air temperature and the temperature of a target object. Therefore, in accordance with the estimation based on the two detected temperatures, the controller20can estimate with high accuracy whether condensation has occurred on the contacts A11and A12, whereby the controller20can estimate with high accuracy whether freezing has occurred on the contacts A11and A12. This highly-accurate estimation can reduce wasteful power consumption occurring as a result of the first application of electric current being executed even when there is no freezing, and can reduce a missed opportunity of dealing with freezing even when such freezing has occurred. Accordingly, a less-wasteful relay system100with fewer malfunctions in the cold season can be achieved.

Furthermore, according to this embodiment, the relay device10includes the first coil161that generates a driving force for switching the contacts A11and A12from the open mode to the closed mode and the second coil162that generates a driving force for switching the contacts A11and A12from the closed mode to the open mode. The above-described first application of electric current involves applying electric current to the second coil162when the contacts A11and A12are in the open mode. Thus, a special drive circuit for performing the first application of electric current is not to be added, and the configuration in which the controller20executes the first application of electric current can be readily achieved.

Furthermore, in this embodiment, as the above-described first application of electric current, the controller20may employ a method involving applying electric current concurrently to the first coil161and the second coil162. With the application of electric current according to this method, heat can be generated from the driving mechanism16by applying electric current thereto in a similar manner without switching the contacts A11and A12between the open and closed modes when the contacts A11and A12are in the open mode or the closed mode. Therefore, the controller20can omit a process for confirming the open or closed mode before executing the first application of electric current. Furthermore, with the application of electric current according to this method, the overall amount of electric current to be applied can be increased relative to a case where electric current is applied to a single coil. Accordingly, freezing can be dealt with more quickly.

The embodiment of the disclosure has been described above. However, the embodiment of the disclosure is not limited to that described above. For example, as an alternative to the above embodiment in which the relay system is equipped in a vehicle, the relay system according to the embodiment of the disclosure is not limited to a vehicle and may be incorporated in any of various apparatuses. For example, the relay system may be incorporated in an industrial machine. Furthermore, as an alternative to the above embodiment in which the relay device is a latching relay, the relay device may be configured to switch between the open and closed modes by applying electric current to the coils and cancelling the application of the electric current to the coils. In this case, the first application of electric current may involve applying electric current flowing in the reverse direction. With such first application of electric current, freezing can be dealt with by applying a large amount of electric current to the coils without switching between the open and closed modes of the relay device set in the open mode or the closed mode as a result of cancelling the application of electric current to the coils. Other details described in the embodiment are appropriately modifiable so long as they do not depart from the scope of the embodiment of the disclosure.

According to the embodiment of the disclosure, by commencing the first application of electric current, a large amount of heat can be generated from the driving mechanism without switching the contacts between the open and closed modes. Therefore, freezing occurring on the contacts can be quickly dealt with when such freezing occurs, while a reduced lifespan of the contacts can be suppressed.