Relay device

Abstract

To provide a technique for suppressing a temperature rise of a PHY included in a relay device.SOLUTION: The PHY311 31 is used for communication with one communication destination, and includes a plurality of transceivers 31 and 312 which are circuit blocks for realizing physical layers in communication. The temperature detector 32 is configured to individually detect the temperature of each of the plurality of PHY311 312. The control unit 34 is configured to execute load distribution control for distributing the communication load of the high-temperature PHY to the other PHYs when the high-temperature PHY, which is the PHY whose temperature detected by the temperature detection unit 32 is equal to or higher than the upper limit value, is detected.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a relay device. [Background technology]

[0002] The following Patent Document 1 describes a relay device that relays communication frames between multiple electronic control units (hereinafter referred to as ECUs) connected via Ethernet. Ethernet is a registered trademark. The relay device and the ECUs each include a transceiver unit (hereinafter referred to as PHY) for transmitting and receiving communication frames (i.e., Ethernet frames). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7107277 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of detailed investigation by the inventors, it was found that with Ethernet, as the amount of communication increases, power consumption increases, causing the temperature of the PHY to rise. One aspect of the present disclosure provides a technique for suppressing a temperature rise in a PHY included in a relay device. [Means for solving the problem]

[0005] One aspect of the present disclosure is a relay device comprising a transceiver unit (31), a temperature detection unit (32), and a control unit (34). The transceiver unit is provided for each device with which the relay device communicates and includes multiple PHYs. The temperature detection unit is configured to individually detect the temperatures of the multiple PHYs. The control unit is configured to, when a high-temperature PHY is detected, which is a PHY whose detected temperature by the temperature detection unit is equal to or higher than a start threshold, execute load balancing control to distribute the communication load of the high-temperature PHY to other PHYs.

[0006] With this configuration, it is possible to suppress the temperature rise of the PHY included in the relay device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the configuration of a communication network. [Figure 2] FIG. 2 is a block diagram showing the configuration of a portion of an ECU that is involved in connecting one transmission line. [Figure 3] 10 is a flowchart of a temperature control process. [Figure 4] 10 is a flowchart of a load distribution process. [Figure 5] 10 is a flowchart of a speed change process in the second embodiment. [Figure 6] FIG. 10 is an explanatory diagram of an operation mode table. [Figure 7] 10 is a flowchart of a speed change process in the third embodiment. [Figure 8] FIG. 11 is a block diagram showing the configuration of a portion related to the connection of one transmission line in an ECU according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. [1. First embodiment] [1-1.Configuration] The communication network 1 shown in Fig. 1 is mounted on a vehicle. In the communication network 1, a plurality of electronic control units (hereinafter referred to as ECUs) 2 are interconnected via a transmission path 4 that communicates using the Ethernet protocol. Ethernet is a registered trademark.

[0009] The plurality of ECUs 2 are classified into a central ECU 21, a plurality of zone ECUs 22, and a plurality of end ECUs 23. The central ECU 21 is connected to a plurality of zone ECUs 22 via individual transmission lines 4. The central ECU 21 controls the plurality of zone ECUs 22 and realizes coordinated control of the entire vehicle.

[0010] The zone ECU 22 is provided for each zone that divides the area inside the vehicle. Each zone ECU 22 is connected to a plurality of end ECUs 23 present in the zone via an individual transmission line 4. The zone ECU 22 controls the plurality of end ECUs 23 and realizes coordinated control within the zone.

[0011] The central ECU 21 and the plurality of zone ECUs 22 are also referred to as relay devices. The plurality of ECUs 2 are connected in a star configuration, and each transmission line 4 connects two ECUs 2 one-to-one.

[0012] The configuration of one port in the ECU 2 to which the transmission line 4 is connected will be described with reference to FIG. The transmission line 4 is redundant and includes two signal lines 41 and 42 that can be operated independently.

[0013] The ECU 2 includes a transceiver unit 31, a temperature detection unit 32, an information acquisition unit 33, and a control unit 34. Although not shown in the figure, the transceiver unit 31 and the temperature detection unit 32 are provided for each port that the ECU 2 has.

[0014] The transceiver unit 31 includes two PHYs 311 and 312. The PHYs 311 and 312 are circuit blocks that implement the physical layer functions of Ethernet. The PHYs 311 and 312 are each connected to one of two signal lines 41 and 42 of the transmission path 4.

[0015] The temperature detection unit 32 includes two temperature sensors 321 and 322, which are provided corresponding to the PHYs 311 and 312, respectively. Here, the temperature sensor 321 detects the temperature of the PHY 311, and the temperature sensor 322 detects the temperature of the PHY 312.

[0016] The information acquisition unit 33 acquires safety information necessary for determining safety conditions from each part of the vehicle. The safety conditions may be, for example, whether or not the situation is such that the frequency of communication over the communication network 1 is sufficiently reduced (for example, when the vehicle is stopped or parked) with regard to information related to the safety of vehicle driving. In this case, the safety information may include, for example, information indicating the operating position of the shift lever, information indicating the operating state of the parking brake, information indicating the amount of operation of the brake pedal, information indicating the vehicle speed, etc.

[0017] The control unit 34 includes a microcomputer including a CPU 341, a ROM 342, a RAM 343, etc. Various functions of the microcomputer are realized by the CPU 341 executing a program stored in a non-transitory physical recording medium. In this example, the ROM 342 corresponds to the non-transitory physical recording medium storing the program. Furthermore, by executing this program, a method corresponding to the program is performed.

[0018] The control unit 34 executes at least protocol processing, temperature control processing, and load balancing processing. The protocol processing is processing for handling communication frames transmitted and received via the transceiver unit 31 in accordance with the Ethernet protocol. The protocol processing may include processing for negotiating with the ECU with which the control unit 34 communicates to set communication speeds and the like. The protocol processing may implement a redundancy protocol specified in, for example, IEEE802.1CB or IEEE802.1AX. The temperature control processing is processing for controlling the operation of the transceiver unit 31 in accordance with the detection result of the temperature detection unit 32.

[0019] [1-2. Processing] Next, the temperature control process executed by the control unit 34 for each port will be described with reference to the flowchart of FIG.

[0020] The temperature control process is repeatedly executed when the ECU 2 is started. In the initial state where the ECU2 is activated, the transceiver unit 31 is set to an operable state for both PHYs 311 and 312. However, according to the upper communication protocol, communication traffic is allocated only to PHY311, and PHY312 is in an unused state. That is, the communication traffic is set to be allocated to PHY311 and PHY312 at a ratio of 100:0.

[0021] When the temperature control process starts, in S110, the control unit 34 acquires the temperatures of each of the PHYs 311 and 312 via the temperature detection unit 32. In S120, the control unit 34 determines whether the load distribution process is being executed. If it is being executed, the process proceeds to S130; if not, the process proceeds to S150.

[0022] In S130, the control unit 34 determines whether the start condition for starting the load distribution process is satisfied. Specifically, the start condition uses whether the maximum temperature Tmax among the temperatures detected for each of the plurality of PHYs 311 and 312 is equal to or higher than the start threshold THs. The start threshold THs may be set, for example, to a value slightly lower than the upper limit value of the operating temperature of the PHYs 311 and 312 by a predetermined margin. If the control unit 34 determines that Tmax ≧ THs, the process proceeds to S140; if it determines that Tmax < THs, the temperature control process ends.

[0023] In S140, the control unit 34 starts the load distribution process that changes the operation of the transceiver unit 31 so that the heat generation of the PHY in which the maximum temperature Tmax is detected, and thus the entire transceiver unit 31, is suppressed, and ends the temperature control process.

[0024] In S150, the control unit 34 determines whether there are multiple PHYs whose detected temperature T is equal to or higher than the start threshold THs. If there are multiple, the process proceeds to S160; if there is one or less, the process proceeds to S170.

[0025] In S160, the control unit 34 relaxes the stop condition, which is the condition for stopping the load distribution process started in the previous S140, and advances the process to S170. The stop condition used is that the maximum temperature TMax is less than the stop threshold value THe. The stop threshold value THe is set to a value sufficiently lower than the start threshold value THs. Therefore, specifically, the stop condition is relaxed by raising the stop threshold value THe by a predetermined value within the range that does not exceed the start threshold value THs. The relaxed stop threshold value THe may be at one level or there may be multiple levels.

[0026] In S170, the control unit 34 determines whether the stop condition for stopping the load distribution process is satisfied. Specifically, as described in S160, it is determined whether the maximum temperature Tmax is less than the stop threshold value THe. If the control unit 34 determines that Tmax < THe, the process proceeds to S180, and if it determines that Tmax ≥ THe, the temperature control process ends.

[0027] In S180, the control unit 34 stops the load distribution process, returns the operating state of the transceiver unit 31 (that is, the setting of the communication traffic distribution ratio and the stop threshold value THe) to the initial state, and ends the temperature control process.

[0028] Next, the load distribution process executed by the control unit 34 will be described using the flowchart of FIG. 4. The load distribution process is a process of dispersing the communication load of the PHY where the maximum temperature Tmax is detected to other PHYs by changing the communication traffic distributed to PHY311, 312 from 100:0 to a predetermined ratio (for example, 50:50 or 0:100, etc.).

[0029] The load distribution process is repeatedly executed from when it is started in the previous S140 until it is stopped in the previous S180. As shown in FIG. 4, when the load distribution process is started, in S210, the control unit 34 calculates the detected temperature difference ΔT, which is the temperature difference between the maximum temperature Tmax and the minimum temperature Tmin among the temperatures detected for each of the plurality of PHYs 311, 312.

[0030] In S220, the control unit 34 determines whether the detected temperature difference ΔT is greater than or equal to the first threshold value TH1. If ΔT ≥ TH1, the process proceeds to S240. If ΔT < TH1, the process proceeds to S230.

[0031] In S230, the control unit 34 determines whether the detected temperature difference ΔT is greater than or equal to the second threshold value TH2 which is set to a value smaller than the first threshold value TH1. If ΔT ≥ TH2, the process proceeds to S250. If ΔT < TH2, the process ends.

[0032] In S240, the control unit 34 stops distributing the communication traffic to the PHY where the highest temperature Tmax is detected, and increases the distribution of the communication traffic to the PHY where the lowest temperature Tmin is detected by the amount decreased due to the stop, and then ends the process. In this case, the distribution of the communication traffic to the PHY with the highest temperature and the PHY with the lowest temperature changes from 100:0 to 0:100.

[0033] In S250, the control unit 34 decreases the distribution of the communication traffic to the PHY where the highest temperature Tmax is detected by a certain ratio, and increases the allocation of the communication traffic to the PHY where the lowest temperature Tmin is detected by the amount of the decrease, and then ends the process. In this case, if the certain ratio is 20, the distribution of the communication traffic to the PHY with the highest temperature and the PHY with the lowest temperature changes from 100:0 to 80:20. If the same state continues, it further changes to 80:20 to 60:40, 40:60, and so on.

[0034] That is, while TH1 > ΔT ≥ TH2, the allocation of the communication traffic to the PHY with the highest temperature is gradually decreased. When ΔT ≥ TH1, the allocation of the communication traffic to the PHY with the highest temperature is immediately stopped. Also, the first threshold value TH1 and the second threshold value TH2 used for determining the detected temperature difference ΔT are set to have hysteresis.

[0035] [1-3. Correspondence of Terms] In this embodiment, the control realized by the control unit 34 executing the load balancing process corresponds to the load balancing control of the present disclosure. In this embodiment, the first threshold value TH1 and the second threshold value TH2 correspond to the temperature difference threshold value of the present disclosure.

[0036] [1-4.Effects] According to the first embodiment described above in detail, the following effects are achieved. (1a) In ECU 2, two PHYs 311 and 312 are provided for each port connected to another ECU 2, and communication is normally performed using one PHY 311. When the temperature of PHY 311 exceeds the start threshold THs, communication traffic is allocated to the other PHY 312. Therefore, further heating of PHY 311 can be suppressed, and the reliability and durability of the communication system can be improved.

[0037] (1b) When distributing communication traffic, the ECU 2 distributes the traffic from the PHY with the highest temperature to the PHY with the lowest temperature according to the detected temperature difference ΔT (=Tmax-Tmin). This allows the temperatures of the PHYs 311 and 312 to be averaged.

[0038] (1c) When the detected temperature difference ΔT is greater than the first threshold TH1, the ECU 2 immediately stops allocating communication traffic to the PHY with the highest temperature, thereby quickly preventing further heating of the PHY with the highest temperature.

[0039] (1d) In the ECU 2, when there are multiple PHYs whose detected temperatures T exceed the start threshold Ts, the conditions for stopping the load sharing process are relaxed. Therefore, it is possible to prevent the PHYs receiving the load sharing process from overheating due to an increase in the load.

[0040] [1-5. Modifications] In the above embodiment, the transceiver unit 31 forming one port is provided with two PHYs 311 and 312, but the transceiver unit 31 may be provided with three or more PHYs.

[0041] In the temperature control process shown in FIG. 3, the processes of S150 and S160, ie, the processes for relaxing the stop conditions, may be omitted. In the above embodiment, in the load balancing process, the allocation of communication traffic is dynamically changed in accordance with the detected temperature difference ΔT. However, it may also be dynamically changed in accordance with the detected temperature T.

[0042] In the load distribution process shown in Fig. 4, steps S230 and S250 may be omitted, and only steps S210, S220, and S240 may be executed. In this case, only one of the multiple PHYs belonging to the transceiver unit 31 operates at any one time. Also, in the load distribution process shown in Fig. 4, steps S220 and S240 may be omitted, and only steps S210, S230, and S250 may be executed. In this case, communication traffic is distributed to all PHYs so that the detected temperatures of the multiple PHYs are averaged.

[0043] In the above embodiment, the allocation of communication traffic to multiple PHYs in the initial state is set to 100:0, but this is not limited to this. That is, multiple PHYs may be set to operate in the initial state. Furthermore, the allocation of communication traffic to multiple PHYs operating in the initial state may be equal or unequal.

[0044] [2. Second Embodiment] [2-1. Differences from the first embodiment] The second embodiment has the same basic configuration as the first embodiment, so differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and reference will be made to the preceding description.

[0045] In the first embodiment described above, the allocation of communication traffic is changed in accordance with the detected temperature difference ΔT. In contrast, the second embodiment differs from the first embodiment in that the communication speed is changed in addition to changing the allocation of communication traffic.

[0046] [2-2. Processing] Next, the control unit 34 of the second embodiment will be described using the flowchart of FIG. 5 for the speed change process that is executed in addition to the protocol process, temperature control process, and load distribution process of the first embodiment.

[0047] In S310, the control unit 34 determines whether the safety conditions are satisfied based on the acquired information from the information acquisition unit 33. Specifically, based on information such as the state of the parking brake, the position of the shift lever, the brake operation amount, and the vehicle speed, it is determined whether the host vehicle is parked or stopped. If the safety conditions are satisfied, the control unit 34 proceeds to S320, and if the safety conditions are not satisfied, the process ends.

[0048] In S320, the control unit 34 selects one of the PHYs belonging to the transceiver unit 31. Hereinafter, the selected PHY will be referred to as the selected PHY. In S330, the control unit 34 acquires the detected temperature T of the selected PHY.

[0049] In S340, the control unit 34 determines whether the detected temperature T is greater than or equal to the third threshold TH3. If it is determined that T≥TH3, the process proceeds to S360, and if it is determined that T<TH3, the process proceeds to S350. The third threshold TH3 is set in the same way as the start threshold THs. The third threshold TH3 may be the same value as the start threshold THs or a different value.

[0050] In S350, the control unit 34 determines whether the detected temperature T is less than the fourth threshold TH4 set to a value smaller than the third threshold. If it is determined that T<TH4, the process proceeds to S370, and if it is determined that T≥TH4, the process proceeds to S380. The fourth threshold TH4 is set in the same way as the end threshold THe. The fourth threshold TH4 may be the same value as the end threshold THe or a different value.

[0051] In S360, the control unit 34 performs a process of reducing the communication speed of the selected PHY to a value lower than the currently set communication speed of the selected PHY, and proceeds to S380. In S370, the control unit 34 performs processing to increase the communication speed of the selected PHY from the communication speed currently set for the selected PHY, and then proceeds to S380.

[0052] The communication speed to be increased or decreased may be set to two levels, or may be set to three or more levels. The lowest communication speed may be 0 bps, i.e., communication may be stopped. In S360 and S370, the communication speed of the PHY is changed using the negotiation function in protocol processing. Specifically, when changing the communication speed, the PHY to be changed is temporarily linked down, the communication speed is agreed upon through negotiation, the PHY settings are changed so that it operates at the agreed communication speed, and then the PHY is linked up and communication is resumed.

[0053] In S380, the control unit 34 determines whether all PHYs belonging to the transceiver unit 31 have been selected. If all PHYs have been selected in the previous S320, the process proceeds to S390. If there is a PHY that has not been selected in the previous S320, the process returns to S320. In this case, in S320, one of the unselected PHYs is selected, and the processes from S330 onwards are repeated.

[0054] In S390, the control unit 34 determines whether there are multiple PHYs for which T≧TH3, and if it determines that there are multiple PHYs, it proceeds to S400, and if it determines that there is one or less PHYs, it ends the processing.

[0055] In S400, the control unit 34 relaxes the condition for increasing the communication speed of the PHY used in the previous S350, and then ends the process. Specifically, the condition is relaxed by raising the fourth threshold TH4 by a predetermined value within a range that does not exceed the third threshold TH3. The fourth threshold TH4 that can be changed by the process in S400 may have only one level, or may have multiple levels.

[0056] [2-3. Terminology] In this embodiment, the control realized by the control unit 34 executing the speed change process corresponds to the speed change control of the present disclosure.

[0057] [2-4. Effects] According to the second embodiment described above in detail, in addition to the effects (1a) to (1d) of the first embodiment described above, the following effects are also achieved.

[0058] (2a) The ECU 2 individually changes the communication speed of each of the PHYs 311 and 312 belonging to the transceiver unit 31 in accordance with the detected temperature T. When the communication speed of the PHYs 311 and 312 is reduced, the power consumption of the PHYs 311 and 312 is reduced, so that the temperature rise of the PHYs 311 and 312 can be suppressed.

[0059] (2b) The ECU 2 performs the speed change process while the safety conditions are met. Therefore, the possibility of safety-related information being exchanged during the link down that occurs when changing the settings of the PHYs 311 and 312 is low, and the degradation of system reliability due to the link down can be suppressed.

[0060] (2c) In ECU2, when multiple PHYs are at high temperatures (i.e., T≧TH3), the conditions for increasing the communication speed are relaxed. Therefore, the number of PHYs whose communication speeds are reduced increases, which prevents the communication performance of the entire system from being reduced for a long time.

[0061] [2-5. Modifications] In the second embodiment, speed change processing is performed in addition to protocol processing, temperature control processing, and load balancing processing, but the temperature control processing and load balancing processing may be omitted and only the protocol processing and speed change processing may be performed.

[0062] 3. Third Embodiment [3-1. Differences from the first and second embodiments] The third embodiment has the same basic configuration as the first and second embodiments, and therefore the differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and reference will be made to the preceding description.

[0063] In the second embodiment described above, the communication speed of the PHY is increased or decreased according to the temperature of the PHY. In contrast, the third embodiment differs from the second embodiment in that the communication speed of the PHY is set using table information indicating the correspondence between the temperature and communication speed of the PHY and the operation mode.

[0064] [3-2. Processing] The control unit 34 has an operation mode table. As shown in FIG. 6, the operation mode table shows information associating the operation mode of the PHY with the temperature and communication speed of the PHY. The operation modes are classified into three types: "H," "M," and "L." "H" is an operation mode set when the detected temperature T of the PHY is greater than 60°C. In the operation mode "H," the communication speed of the PHY is set to 1000 Mbps. "M" is an operation mode set when the detected temperature T of the PHY is greater than 40°C and equal to or less than 60°C. In the operation mode "M," the communication speed of the PHY is set to 2.5 Gbps. "L" is an operation mode set when the detected temperature T is equal to or less than 40°C. In the operation mode "L," the communication speed of the PHY is set to 5 GHz. In other words, the lower the PHY temperature, the faster the communication speed is set.

[0065] In the third embodiment, the speed change processing that the control unit 34 executes in place of the speed change processing of the second embodiment shown in FIG. 5 will be described with reference to the flowchart of FIG. When the speed change process is started, the control unit 34 acquires the detected temperature T of each PHY belonging to the transceiver unit 31 in S510.

[0066] In S520, the control unit 34 uses the operation mode table to select an operation mode for each PHY according to the detected temperature T acquired in S510. In the following, when the operation modes of multiple PHYs belonging to the same transceiver unit 31 are collectively indicated, the operation mode of each PHY is listed in parentheses. For example, (operation mode of PHY 311, operation mode of PHY 312) = (L, L).

[0067] In S530, the control unit 34 determines whether the selected operation mode selected in S520 is different from the set operation mode, which is the currently set operation mode. If the selected operation mode is different from the set operation mode, the control unit 34 proceeds to S540, and if the selected operation mode is the same as the set operation mode, the control unit 34 ends the process.

[0068] In S540, the control unit 34 determines whether the safety conditions are met, and if the safety conditions are met, the process proceeds to S550, and if the safety conditions are not met, the process ends. The determination in S540 is made in the same manner as the determination in S310 described above.

[0069] In S550, the control unit 34 executes a process of switching the communication speed of the PHY from the communication speed corresponding to the set operation mode to the communication speed corresponding to the selected operation mode, updates the set operation mode so that the selected operation mode becomes the new set operation mode, and terminates the process.

[0070] [3-3. Effects] According to the third embodiment described above in detail, the effects (1a) to (1c) of the first embodiment and the effects (2a) and (2b) of the second embodiment are achieved, and further, the following effects are achieved.

[0071] (3a) In the ECU 2, the communication speed setting for each operation mode can be easily changed by simply rewriting the operation mode table. [3-4. Modifications] In the third embodiment, the operation mode table indicates information associating the operation mode of each PHY (e.g., "M" or the like) with the communication speed setting of each PHY, but is not limited to this. For example, the operation mode table may associate an operation mode that combines the operation modes of multiple PHYs (e.g., (L, M) or the like) with the communication speeds of multiple PHYs. In this case, for example, even if the operation mode of the first PHY is "L," the first PHY can be set to a different communication speed depending on the operation mode of the second PHY, thereby achieving more precise control.

[0072] [4. Fourth Embodiment] [4-1. Differences from the first embodiment] The fourth embodiment has the same basic configuration as the first embodiment, so differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and reference is made to the preceding description.

[0073] In the first embodiment described above, a plurality of PHYs 311, 312 and a plurality of temperature sensors 321, 322 are provided for each port to which one transmission line 4 is connected. In contrast, the fourth embodiment differs from the first embodiment in that each port is provided with one PHY 311 and one temperature sensor 321.

[0074] [4-2.Configuration] The configuration of one port to which a transmission line 4a is connected in a relay device (that is, an ECU) 2a of the fourth embodiment will be described with reference to FIG.

[0075] Unlike the transmission line 4, the transmission line 4a includes one signal line 41. The ECU 2a includes a transceiver unit 31a, a temperature detection unit 32a, an information acquisition unit 33, and a control unit .

[0076] The transceiver unit 31a includes a PHY 311. The PHY 311 is connected to a signal line 41 of the transmission line 4a. The temperature detection unit 32a includes a temperature sensor 321. The temperature sensor 321 detects the temperature of the PHY 311.

[0077] The information acquisition unit 33 and the control unit 34 are the same as those in the first embodiment. However, the control unit 34 executes at least the protocol processing and the speed change processing. The protocol processing is the same as that in the first embodiment.

[0078] [4-3. Processing] The speed change process executed by the control unit 34 in the fourth embodiment has the content obtained by omitting S320, S380 to S400 from the flowchart of FIG. 5. However, the selected PHY shall be changed to one PHY belonging to the transceiver unit 31a.

[0079] That is, when the safety condition is satisfied, the communication speed of one PHY 311 belonging to the transceiver unit 31a is controlled to be decreased at high temperature (that is, T ≧ TH3) and increased at low temperature (that is, T < TH4) according to the detected temperature T.

[0080] [4-4. Effects] According to the fourth embodiment described in detail above, the following effects can be obtained. (4a) In the ECU 2a, the communication speed of the PHY 311 is changed according to the detected temperature T of the PHY 311. That is, when the communication speed of the PHY 311 is decreased, the power consumption at the PHY 311 is decreased, and the temperature rise of the PHY 311 can be suppressed.

[0081] (4b) In the ECU 2a, the speed change process is performed when the safety condition is satisfied, that is, when the communication volume related to the information related to the safety of vehicle travel is small. Therefore, it is possible to suppress a decrease in the reliability of the system due to a link down that occurs when the communication speed of the PHY 311 is changed.

[0082] [4-5. Modification Example] In the fourth embodiment, the control unit 34 performs the process based on the flowchart shown in FIG. 5 as the speed change process, but the process based on the flowchart shown in FIG. 7 may be performed.

[0083] [5. Other Embodiments] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented with various modifications.

[0084] (5a) The control unit 34 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit 34 and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit 34 and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible recording medium. The method for implementing the functions of each unit included in the control unit 34 does not necessarily need to include software; all of the functions may be implemented using one or more hardware devices.

[0085] (5b) Multiple functions of one component in the above embodiments may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0086] (5c) In addition to the relay device described above, the present disclosure can also be realized in various forms, such as a system including the relay device as a component, a program for causing a computer to function as the relay device, a non-transient physical recording medium such as a semiconductor memory on which the program is recorded, and a method for optimizing PHY temperature.

[0087] [6. Technical Ideas Disclosed in the Present Specification] [Item 1] a transceiver unit (31) provided for each device to be communicated with and having a plurality of PHYs; a temperature detection unit (32) configured to individually detect the temperatures of the plurality of PHYs; a control unit (34) configured to execute load balancing control to distribute a communication load of the high-temperature PHY to another PHY when a high-temperature PHY is detected, the PHY having a temperature detected by the temperature detection unit equal to or higher than a start threshold; A relay device comprising:

[0088] [Item 2] The relay device according to item 1, The control unit starts the load distribution control when the detected temperature is equal to or higher than the start threshold, and stops the load distribution control when the detected temperature is lower than a stop threshold set to a value lower than the start threshold. Relay device.

[0089] [Item 3] The relay device according to item 2, When the detected temperatures of the plurality of PHYs are all equal to or higher than the start threshold, the control unit changes the stop threshold so that a stop condition for the load balancing control is relaxed. Relay device.

[0090] [Item 4] The relay device according to any one of items 1 to 3, The control unit, as the load distribution control, designates the PHY with the highest detected temperature as a highest PHY and the PHY with the lowest detected temperature as a lowest PHY, and determines a difference between the detected temperature of the highest PHY and the detected temperature of the lowest PHY as a detected temperature difference, and reduces communication traffic allocated to the highest PHY when the detected temperature difference is equal to or greater than a temperature difference threshold, and increases communication traffic allocated to the highest PHY when the detected temperature difference is less than the temperature difference threshold. Relay device.

[0091] [Item 5] Item 4. The relay device according to item 4, The control unit, as the load distribution control, increases communication traffic allocated to the lowest PHY when the detected temperature difference is equal to or greater than the temperature difference threshold, and decreases communication traffic allocated to the lowest PHY when the detected temperature difference is less than the temperature difference threshold. Relay device.

[0092] [Item 6] Item 4 or Item 5. The relay device according to item 4 or 5, The temperature difference threshold is set to have hysteresis. Relay device.

[0093] [Item 7] Item 6: A relay device according to any one of items 1 to 6, the control unit executes speed change control to reduce the communication speed of the PHY whose detected temperature is higher than a predetermined temperature from the current communication speed of the PHY, and to increase the communication speed of the PHY whose detected temperature is lower than the predetermined temperature from the current communication speed of the PHY. Relay device.

[0094] [Item 8] Item 7. The relay device according to item 7, The relay device is mounted on a vehicle, further comprising an information acquisition unit (33) configured to acquire information relating to the state of the vehicle; the control unit executes the speed change control during a period in which a safety condition is satisfied, the safety condition being that the state of the vehicle determined from the information acquired by the information acquisition unit indicates a situation in which a communication frequency of information related to the safety of vehicle traveling is lower than a predetermined value. Relay device.

[0095] [Item 9] Item 8. The relay device according to item 8, The safety conditions include the vehicle being parked or stopped. Relay device.

[0096] [Item 10] A relay device mounted on a vehicle, a transceiver unit (31a) provided for each device to be communicated with and having a PHY; a temperature detection unit (32a) configured to detect the temperature of the PHY; an information acquisition unit (33) configured to acquire information about the state of the vehicle; a control unit (24) configured to execute speed change control in accordance with a temperature detected by the temperature detection unit during a period in which a safety condition is satisfied, the control unit determining that the state of the vehicle determined from the information acquired by the information acquisition unit indicates a situation in which a communication frequency of information related to the safety of vehicle driving is lower than a predetermined value, and the control unit (24) configured to execute speed change control in accordance with a temperature detected by the temperature detection unit, the higher the detected temperature, the lower the communication speed of the PHY; A relay device comprising:

[0097] [Item 11] Item 10: A relay device according to item 10, The control unit starts the speed change control when the detected temperature is equal to or higher than a start threshold, and stops the speed change control when the detected temperature is lower than a stop threshold set to a value lower than the start threshold. Relay device. [Explanation of symbols]

[0098] 1...communication network, 2...ECU, 4...transmission path, 21...central ECU, 22...zone ECU, 23...terminal ECU, 31...transceiver unit, 32...temperature detection unit, 33...information acquisition unit, 34...control unit, 41, 42...signal line, 311, 312...PHY, 321, 322...temperature sensor, 341...CPU, 342...ROM, 343...RAM.

Claims

1. a transceiver unit (31) provided for each device to be communicated with and having a plurality of PHYs; a temperature detection unit (32) configured to individually detect the temperatures of the plurality of PHYs; a control unit (34) configured to execute load balancing control to distribute a communication load of the high-temperature PHY to another PHY when a high-temperature PHY is detected, the PHY having a temperature detected by the temperature detection unit equal to or higher than a start threshold; A relay device comprising:

2. The relay device according to claim 1, The control unit starts the load distribution control when the detected temperature is equal to or higher than the start threshold, and stops the load distribution control when the detected temperature is lower than a stop threshold set to a value lower than the start threshold. Relay device.

3. The relay device according to claim 2, When the detected temperatures of the plurality of PHYs are all equal to or higher than the start threshold, the control unit changes the stop threshold so that a stop condition for the load balancing control is relaxed. Relay device.

4. The relay device according to claim 1, The control unit, as the load distribution control, sets the PHY with the highest detected temperature as a highest PHY and the PHY with the lowest detected temperature as a lowest PHY, sets a difference between the detected temperature of the highest PHY and the detected temperature of the lowest PHY as a detected temperature difference, and reduces communication traffic allocated to the highest PHY when the detected temperature difference is equal to or greater than a temperature difference threshold, and increases communication traffic allocated to the highest PHY when the detected temperature difference is less than the temperature difference threshold. Relay device.

5. The relay device according to claim 4, The control unit, as the load distribution control, increases communication traffic allocated to the lowest PHY when the detected temperature difference is equal to or greater than the temperature difference threshold, and decreases communication traffic allocated to the lowest PHY when the detected temperature difference is less than the temperature difference threshold. Relay device.

6. 6. The relay device according to claim 4 or claim 5, The temperature difference threshold is set to have hysteresis. Relay device.

7. The relay device according to claim 1, the control unit executes speed change control to reduce the communication speed of the PHY whose detected temperature is higher than a predetermined temperature from the current communication speed of the PHY, and to increase the communication speed of the PHY whose detected temperature is lower than the predetermined temperature from the current communication speed of the PHY. Relay device.

8. The relay device according to claim 7, The relay device is mounted on a vehicle, An information acquisition unit (33) configured to acquire information about the state of the vehicle, the control unit executes the speed change control during a period in which a safety condition is satisfied, the safety condition being that the state of the vehicle determined from the information acquired by the information acquisition unit indicates a situation in which a communication frequency of information related to the safety of vehicle traveling is lower than a predetermined value. Relay device.

9. The relay device according to claim 8, The safety conditions include the vehicle being parked or stopped. Relay device.

Images