Patent Description:
A vehicle is equipped with a plurality of in-vehicle devices each called an electronic control unit (ECU). One mode of operation control of the ECUs will be described with reference to <FIG>. In the example shown in <FIG>, power from a power supply <NUM> is supplied to an ECU <NUM> as battery (+B) power of a +B power supply, accessory (ACC) power of an ACC power supply, and ignition (IG) power of an IG power supply via three power lines <NUM>, <NUM>, and <NUM>, respectively. The power line <NUM> directly connects the power supply <NUM> and the ECU <NUM>, and power is constantly supplied by the power line <NUM>. The power line <NUM> connects the power supply <NUM> and the ECU <NUM> via an ACC relay <NUM>. The power line <NUM> connects the power supply <NUM> and the ECU <NUM> via an IG relay <NUM>. A power supply management ECU <NUM> detects a user's operation of turning on an ACC or an IG using a key or a push switch, and operates the ACC relay <NUM> via a control line <NUM> and the IG relay <NUM> via a control line <NUM> in accordance with the detected operation. For example, when detecting the ACC ON operation, the power supply management ECU <NUM> closes the ACC relay <NUM> to supply power via the power line <NUM>. Further, when detecting the IG ON operation, the power supply management ECU <NUM> closes the IG relay <NUM> to supply power via the power line <NUM>.

The ECU <NUM> performs an operation in accordance with a combination of whether the +B power of the +B power supply, the ACC power of the ACC power supply, and the IG power of the IG power supply are supplied via the three power lines <NUM>, <NUM>, and <NUM>. For example, when the ACC power of the ACC power supply is supplied, the ECU <NUM> executes a predetermined operation determined as the operation for an ACC ON state, and when the IG power of the IG power supply is supplied, the ECU <NUM> executes a predetermined operation determined as the operation for an IG ON state. A communication line <NUM> connects the power supply management ECU <NUM> and the ECU <NUM>, and the power supply management ECU <NUM> and the ECU <NUM> can communicate with each other. One or two of the +B power supply, the ACC power supply, and the IG power supply may be omitted depending on the specifications of the ECU <NUM>.

As another mode of the operation control of the ECU, a mode has been proposed in which a function called a network management (NM) function is added to the ECU to reduce the number of power lines compared to the mode shown in <FIG>. The NM function includes a function that enables control on a bus basis to switch the state of each ECU connected to a communication bus between a standby state in which operation is suppressed and a startup state in which operation can be executed (<CIT> (<CIT>)). In the example illustrated in <FIG>, an ECU <NUM> includes an NM unit <NUM> that has the NM function, and power from the power supply <NUM> is supplied to the ECU <NUM> only as the +B power of the +B power supply via the power line <NUM>. A power supply management ECU <NUM> detects a user's operation of turning on the ACC or the IG using a key or a push switch, and instructs the ECU <NUM> via the communication line <NUM> in accordance with the detected operation.

In the standby state, the NM unit <NUM> waits for the above-described instruction from the power supply management ECU <NUM>, and upon receiving the instruction, shifts the ECU <NUM> to the startup state. This instruction is a message in a format conforming to the specification of the NM function, and the message can include, for example, information such as ACC ON and IG ON. After transitioning to the startup state, the ECU <NUM> further executes the predetermined operations for the ACC ON state or the IG ON state based on the information included in the instruction. In the startup state of the ECU <NUM>, when the NM unit <NUM> determines that the ECU <NUM> may transition to the standby state based on the operation state of the ECU <NUM> and communication with the power supply management ECU <NUM> or the like, the NM unit <NUM> can cause the ECU <NUM> to transition to the standby state.

In the example shown in <FIG>, the number of power lines, relays, or the like can be reduced, and therefore costs can be reduced, as compared with the example shown in <FIG>.

<CIT> discloses a vehicle-mounted network system which includes a plurality of electronic control units (ECUs) communicatively connected to a communication path of a vehicle-mounted network, each of which is configured to selectively perform a normal mode of operation and a sleep mode, and a management apparatus. The plurality of ECUs are configured to be individually powered on and off by a power supply relay of the management apparatus. The management apparatus is configured to acquire information indicative of a vehicle situation and determine a scene from the acquired information, determine control contents for powering on or off at least one specific ECU, of the plurality of ECUs, corresponding to the determined scene, if any, and power on or off the at least one specific ECU based on the determined control contents.

<CIT> discloses a microcomputer of an ECU which is a master which determines whether to turn on or off the power supply of a slave ECU, and outputs a power supply control signal indicating power-on/off via serial communication on the basis of the result of determination. A signal superposition circuit accepts the output power supply control signal and transmits the accepted power supply control signal to a CAN bus to which a CAN transceiver is connected. In the slave ECU, a signal separation circuit individually receives a CAN communication signal and a serial communication signal transmitted to the CAN bus, while an input/output control circuit to which the serial communication signal is input as the power supply control signal outputs a signal to the power supply circuit to control power-on/off of the microcomputer.

Since the ECU including the NM function consumes standby power even in the standby state in which the ECU does not need to operate, the standby power increases in a network system that includes a large number of ECUs.

The invention provides an in-vehicle network system in which standby power is suppressed. The present invention is defined in the appended independent claim <NUM> to which reference should be made.

A network system according to the invention employs an NM function to reduce the number of power lines or the like. In the network system, an ECU that does not need to be currently started is set to a power-off state in which no power is consumed, instead of a standby state of the NM function in which standby power is consumed, and when the need for starting the ECU occurs, power is supplied to set a startup state after the standby state. Thereby, the standby power of the network system can be suppressed.

Hereinafter, an embodiment of the invention will be described in detail with reference to the drawings.

<FIG> is a diagram showing a configuration of a network system <NUM> according to the embodiment.

The network system <NUM> includes a tree-type connection topology. <FIG> shows a configuration in which two intermediate nodes are subordinate to one upper node, and three lower nodes are subordinate to each of the intermediate nodes. In <FIG>, an upper ECU <NUM> is the upper node. A first intermediate ECU <NUM> and a second intermediate ECU <NUM> are the intermediate nodes. First lower ECUs <NUM> are the lower nodes subordinate to the first intermediate ECU <NUM>, and second lower ECUs <NUM> are the lower nodes subordinate to the second intermediate ECU <NUM>. The network system <NUM> is mounted on a vehicle and includes the ECUs described above and a power supply <NUM> that supplies power to the ECUs. In the following description, as the intermediate nodes, two ECUs, namely, the first intermediate ECU <NUM> and the second intermediate ECU <NUM>, are provided. However, the number of the intermediate nodes and the number of the lower nodes subordinate to each of the intermediate nodes are not specifically limited. That is, two ECUs are provided as the intermediate nodes in this embodiment, but an ECU may be provided as the intermediate node, and three or more ECUs may be provided as the intermediate node. Furthermore, three ECUs are provided as the lower nodes subordinate to each of the intermediate nodes in this embodiment, but two or less ECUs may be provided as the lower nodes, and four or more ECUs may be provided as the lower nodes.

As an example, the upper ECU <NUM> is a relatively highly functional ECU that collectively performs computations for various vehicle control functions. The lower ECUs such as the first lower ECUs <NUM> and the second lower ECUs <NUM> are, for example, ECUs provided in each component of the vehicle and having relatively specialized functions for individually controlling each sensor or each actuator. The intermediate ECUs such as the first intermediate ECU <NUM> and the second intermediate ECU <NUM> are ECUs that function as gateways that relay communication between the upper ECU <NUM> and the lower ECUs. The first intermediate ECU <NUM> relays communication between the upper ECU <NUM> and the first lower ECUs <NUM>. The second intermediate ECU <NUM> relays communication between the upper ECU <NUM> and the second lower ECUs <NUM>. These ECUs are typically configured to include a control unit such as a processor or a microcomputer and a memory.

The upper ECU <NUM> and the first intermediate ECU <NUM> are connected by a communication line <NUM>. The first intermediate ECU <NUM> and the first lower ECUs <NUM> are connected by a communication line (bus) <NUM>. The upper ECU <NUM> and the second intermediate ECU <NUM> are connected by a communication line <NUM>. The second intermediate ECU <NUM> and the second lower ECUs <NUM> are connected by a communication line (bus) <NUM>. Communication between the upper ECU <NUM> and the first intermediate ECU <NUM> and communication between the upper ECU <NUM> and the second intermediate ECU <NUM> are performed in accordance with, for example, the Ethernet (registered trademark) standard. However, the communication standard is not limited thereto. Communication between the first intermediate ECU <NUM> and the first lower ECUs <NUM> and communication between the second intermediate ECU <NUM> and the second lower ECUs <NUM> are performed in accordance with, for example, the controller area network (CAN; registered trademark) standard. However, the communication standard is not limited thereto.

The power supply <NUM> is connected to the first intermediate ECU <NUM> and the second intermediate ECU <NUM> by a power line <NUM>. The first intermediate ECU <NUM> and the first lower ECUs <NUM> are connected by a power line <NUM>. Further, the second intermediate ECU <NUM> and the second lower ECUs <NUM> are connected by a power line <NUM>. Each of the first intermediate ECU <NUM> and the second intermediate ECU <NUM> includes a relay <NUM>. The relay <NUM> of the first intermediate ECU <NUM> can switch between a disconnected state and a connected state of the power line <NUM> and the power line <NUM>. The relay <NUM> of the second intermediate ECU <NUM> can switch between a disconnected state and a connected state of the power line <NUM> and the power line <NUM>. Although not shown, the power supply <NUM> and the upper ECU <NUM> may be connected by the power line <NUM>, or may be connected by another power line provided separately from the power lines described above.

Each of the first intermediate ECU <NUM> and the second intermediate ECU <NUM> includes an NM unit <NUM>. Each of the first lower ECUs <NUM> and the second lower ECUs <NUM> includes an NM unit <NUM>. The NM units <NUM> and <NUM> have the network management (NM) function described above, and perform control to switch the state of each ECU between the standby state in which operation is suppressed and the startup state in which various operations can be executed.

The upper ECU <NUM> collects, for example, information on the vehicle and surrounding conditions of the vehicle from the first lower ECUs <NUM> and the second lower ECUs <NUM> that control the sensors. This information may include, for example, operational conditions of the actuators, etc., driving conditions of the vehicle such as vehicle speed and acceleration, environmental conditions of the vehicle such as roads and objects surrounding the vehicle, a seating status of an occupant, and details of operations performed with respect to each component of the vehicle. The upper ECU <NUM> performs computations based on this information and generates control data. The control data is data for controlling various functions of the vehicle, such as an autonomous driving function, a self-parking function, drive assistance functions including collision avoidance, lane keeping, automatic follow-up of the preceding vehicle, and cruise control, operational control of an engine, a transmission, a cooling device, and an air conditioner, charging and discharging control of a battery, lighting of headlamps in accordance with illuminance, permission of unlocking doors based on authentication using a mobile device (electronic key), and presentation of information to a user. The upper ECU <NUM> transmits the control data as appropriate to the first lower ECUs <NUM> and the second lower ECUs <NUM> that control the actuators to cause the actuators to operate in accordance with the control data. In the network system <NUM>, cost is reduced by concentrating various control functions of the vehicle in the upper ECU <NUM> and relatively simplifying the configurations of the first lower ECUs <NUM> and the second lower ECUs <NUM> instead.

A startup process of the network system <NUM> according to the embodiment will be described below. <FIG> is a flowchart showing the startup process. As an example, a description will be given with reference to <FIG> of a process in which, of the lower nodes, the three first lower ECUs <NUM> subordinate to the first intermediate ECU <NUM> are started as one target startup group. At the start of this process, the first intermediate ECU <NUM> is in the standby state as an initial state. The relay <NUM> of the first intermediate ECU <NUM> is opened such that the power line <NUM> and the power line <NUM> are not connected, and the first lower ECUs <NUM> are in a power-off state.

When determining that it is necessary to start the first lower ECUs <NUM>, the upper ECU <NUM> transmits a message to the first intermediate ECU <NUM> via the communication line <NUM>.

The upper ECU <NUM> can determine whether it is necessary to start the first lower ECUs <NUM> and what operation is to be performed by the first lower ECUs <NUM> when the first lower ECUs <NUM> are started, based on, for example, information received from another ECU that has already been started. A specific method of such determination is determined in accordance with operation specifications of the first lower ECUs <NUM>, operation requirements of the entire vehicle, or the like. For example, when the upper ECU <NUM> receives, from the ECU that controls a push switch, information indicating that the user has pressed the push switch to perform an operation of instructing the power supply of the vehicle to switch from the OFF state to the IG ON state, the upper ECU <NUM> can determine that it is necessary to cause the first lower ECUs <NUM> to perform the operation for the IG ON state. The message includes an instruction to cause the subordinate nodes to transition to the startup state, and information used to specify the operation of the first lower ECUs <NUM> such as IG ON. The operation of the first lower ECUs <NUM> is not defined by only the conventional power supply state such as ACC ON and IG ON, but can be variously defined in accordance with advanced functions of the vehicle and the ECU.

The first intermediate ECU <NUM> receives the message. The NM unit <NUM> causes the first intermediate ECU <NUM> to transition from the standby state to the startup state in accordance with the instruction in the message to transition to the startup state.

The first intermediate ECU <NUM> closes the relay <NUM> to connect the power line <NUM> and the power line <NUM>, and starts power supply from the power supply <NUM> to the first lower ECUs <NUM> via the first intermediate ECU <NUM>.

When power is supplied to the first lower ECUs <NUM>, the NM units <NUM> cause the first lower ECUs <NUM> to transition to the standby state as the initial state.

The first intermediate ECU <NUM> converts a format of the message transmitted from the upper ECU <NUM> as appropriate in accordance with a difference in the communication standard, and relays the message to the first lower ECUs <NUM> in the standby state. Note that the first intermediate ECU <NUM> can appropriately detect that the first lower ECUs <NUM> have transitioned to the standby state, for example, through communication with the first lower ECU <NUM>.

The first lower ECUs <NUM> receive the message. The NM units <NUM> cause the first lower ECUs <NUM> to transition from the standby state to the startup state in accordance with the instruction in the message to transition to the startup state. The first lower ECUs <NUM> specify and execute the operation based on the information included in the message and specifying the operation such as IG ON.

Communication for controlling various functions of the vehicle is started. The first intermediate ECU <NUM> relays communication between the upper ECU <NUM> and the first lower ECUs <NUM>. The first lower ECUs <NUM> also communicate with each other. Thus, the startup process of the first lower ECU <NUM> ends. After that, when the upper ECU <NUM> determines that the first lower ECUs <NUM> do not need to be operated, for example, by detecting that the user has performed an operation such as IG OFF, the upper ECU <NUM> causes the first lower ECUs <NUM> to transition to the standby state, causes the relay <NUM> of the first intermediate ECU <NUM> to open to stop power supply, and causes the first intermediate ECU <NUM> to transition to the standby state, conforming to the NM function.

In the above description, the instruction to cause the first intermediate ECU <NUM> and the first lower ECUs <NUM> to transition to the startup state and the information used to specify the operation of the first lower ECUs <NUM> such as IG ON are included in the same message.

In the network system <NUM> described above, the upper ECU <NUM> and the first intermediate ECU <NUM> are connected by the communication line <NUM>, and the upper ECU <NUM> and the second intermediate ECU <NUM> are connected by the communication line <NUM> that is different from the communication line <NUM>. That is, the upper node and each intermediate node are not connected by a one-to-many bus connection, but are connected by a one-to-one connection with a dedicated line. This is because, in order for the upper node to communicate with many lower nodes connected by each intermediate node without interruption, providing a dedicated line between the upper node and the intermediate node can facilitate a design that guarantees a sufficient band rather than bus connection. However, as a modification, a mode in which the upper node and each intermediate node are connected by a one-to-many bus connection may be adopted. In this case, a part of the process described above is changed. The changes to be made will be described below.

In the mode in which the upper ECU <NUM> is connected to the first intermediate ECU <NUM> and the second intermediate ECU <NUM> by a bus, the messages transmitted from the upper ECU <NUM> to the first intermediate ECU <NUM> include a message for starting the first lower ECUs <NUM> subordinate to the first intermediate ECU <NUM> and a message for starting the second lower ECUs <NUM> subordinate to the second intermediate ECU <NUM>. In step S102, the first intermediate ECU <NUM> transitions from the standby state to the startup state in accordance with the standard of the NM function, regardless of the message received.

In step S102, the first intermediate ECU <NUM> that has transitioned to the startup state determines whether it is necessary to start the subordinate first lower ECUs <NUM> based on the received message. This determination can be made when the upper ECU <NUM> transmits the message including information necessary for the determination, and the first intermediate ECU <NUM> refers to this information. This information may be information such as the IG ON described above, or may be information that more specifically specifies the first lower ECUs <NUM>.

When the first intermediate ECU <NUM> determines that the first lower ECUs <NUM> need to be started, the process proceeds to step S103. When the first intermediate ECU <NUM> determines that the first lower ECUs <NUM> do not need to be started, the first intermediate ECU <NUM> waits to receive the next message from the upper ECU <NUM>. Thereafter, when the first intermediate ECU <NUM> determines that the first lower ECUs <NUM> need to be started based on the next message received, the process proceeds to step S103, and when the first intermediate ECU <NUM> determines that the first lower ECUs <NUM> do not need to be started based on the next message received, the first intermediate ECU <NUM> repeats the process of waiting to receive the next message.

In the embodiment and modification, the process when the first lower ECUs <NUM> subordinate to the first intermediate ECU <NUM> are started has been described as an example. A similar process may be performed when the second lower ECUs <NUM> subordinate to the second intermediate ECU <NUM> are started.

The network system <NUM> according to the embodiment and the modification employs the NM function to reduce the number of power lines or the like, and the lower ECUs that do not need to be currently started are set to the power-off state in which no power is consumed, instead of the standby state of the NM function in which the standby power is consumed. When the need for starting the lower ECUs occurs, power is supplied to set the startup state after the standby state. This suppresses the standby power even when the number of the lower ECUs is large. Also, by grouping the lower ECUs under a plurality of the intermediate ECUs, starting can be instructed in groups, so that only the lower ECUs in the group that need to be started can be started, and the power-off state of the other lower ECUs can be maintained without being started in conjunction with the group started above. Thus, power consumption can be suppressed.

The ECUs do not need to include the NM function, and the lower ECUs may be started when the intermediate ECU starts power supply to the lower ECUs in response to an instruction from the upper ECU. Also in this case, the effect of suppressing power consumption by the startup control in groups described above can be obtained.

The invention is not limited to the network system, and can be implemented as a method of controlling the network system, a control program for the network system to be performed by the ECU having a processor and a memory and a computer-readable non-transitory storage medium that stores the control program, and a vehicle equipped with the network system, etc. In addition, the invention can be applied to network systems other than the network system mounted on the vehicle.

Claim 1:
An in-vehicle network system comprising:
a power supply (<NUM>);
an upper electronic control unit (<NUM>);
a plurality of intermediate electronic control units (<NUM>, <NUM>); and
a plurality of lower electronic control units (<NUM>, <NUM>) subordinate to each of the intermediate electronic control units,
wherein:
an intermediate electronic control unit (<NUM>, <NUM>) is configured to:
receive power supplied from the power supply;
maintain the lower electronic control units subordinate to the intermediate electronic control unit in a power-off state until the intermediate electronic control unit receives a message from the upper electronic control unit;
communicate with the upper electronic control unit and function as a gateway configured to relay communication between the upper electronic control unit and the plurality of lower electronic control units subordinate to the intermediate electronic control unit;
transition from a standby state to a startup state and supply the power supplied from the power supply to the lower electronic control units subordinate to the intermediate electronic control unit in response to the message transmitted from the upper electronic control unit; and
transmit a message to the lower electronic control units subordinate to the intermediate electronic control unit in the standby state in response to the message transmitted from the upper electronic control unit,
and:
the lower electronic control units (<NUM>, <NUM>) subordinate to the intermediate electronic control unit are configured to:
transition, when the power is supplied from the power supply, from the power-off state to a standby state to wait for an instruction;
communicate with the intermediate electronic control unit;
transition from the standby state to a startup state in response to the message transmitted from the intermediate electronic control unit; and
specify an operation in the startup state in response to the message transmitted from the intermediate electronic control unit.