In-vehicle power distribution device

Abstract

To provide an on-vehicle power distribution device which easily performs additional connection of even new electrical components and new functions that are not assumed at design time thereof without making parts such as a wiring harness or the like larger than necessary.SOLUTION: Priority of each load, which is connected to a downstream side of an ECU having power source power distribution function has been previously grasped. Each power source current Ix flowing to each load is detected, and a total current value Iy flowing an electric wire on an upstream side of the ECU is calculated. A relation of "upstream electric wire smoke generation characteristic C0>upstream fuse fusion cutting characteristic C1>power control characteristic C2" is established, and when the total current value Iy approaches the power control characteristic C2, electric conduction of a load with lower priority is blocked or switched to PWM control to reduce the total current value Iy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an in-vehicle power distribution device.

Background Art

[0002] In recent years, with the progress of vehicle autonomous driving and driving assistance technologies, the number of devices such as sensors, electric loads, and ECUs (electronic control units) mounted on vehicles, that is, electrical components, has been increasing steadily. For these electrical components, in general vehicles, power is supplied from a power source such as an in-vehicle battery to each of them via a wire harness. In addition, a power box may be used to enable connection of multiple systems of electrical components to the downstream side of the in-vehicle power source.

[0003] For example, Patent Document 1 discloses a technology that enables easy addition of a connection target device to a power box. The in-vehicle system of Patent Document 1 includes a power box provided in a vehicle, having a plurality of device connectors and a control unit 2 that supplies power received from a power source to the plurality of device connectors, and a switch that switches between interruption and permission of power supply to the plurality of device connectors in the power box. Further, when the power supply to the device connector is permitted by the switch, the control unit executes a connection target confirmation process for identifying the type of the connection target device connected to the device connector and specifying the position of the device connector to which the connection target device is connected.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, the power box shown in Patent Document 1 is pre-equipped with connectors for connecting optional devices. Therefore, if a predetermined optional device is retrofitted to the empty connectors of the power box, vehicle-side power can be supplied to the optional device via the power box.

[0006] By the way, with the progress of vehicle autonomous driving technology and driving assistance technology, there is a possibility that new electrical components and functions that were not assumed at the initial stage of vehicle development may be added to the in-vehicle system by retrofitting. Also, in that case, if the specifications such as power consumption of each retrofitted electrical component are determined to be low in advance, there will be significant restrictions on the functions that can be retrofitted, and the degree of design freedom will be reduced.

[0007] On the other hand, components such as fuses, power supply wires, or busbars are usually provided at the connection parts between a power source such as an in-vehicle battery and a power box. Also, the specifications of the fuse are determined so that the energization can be cut off before abnormalities such as smoking occur in the wire due to the influence of an overcurrent exceeding the allowable current of the power supply wire.

[0008] Therefore, it is necessary to pre-determine the specification of the upper limit value of the current consumed by all the electrical components connected to the downstream side of the power box or the like, determine the thickness or cross-sectional area of the core wire of the power supply wire based on this upper limit value, and further determine the cutoff characteristics of the fuse.

[0009] However, when a new electrical component that was not assumed at the initial stage of vehicle development is added and this electrical component is connected to the downstream side of the power box, the total current flowing through the downstream side of the power box may exceed the specification of the current upper limit value in the upstream wire. In that case, it is necessary to increase the size of components such as wires, terminals, and fuses of the wire harness on the upstream side of the power box, but such a modification is not easy. Also, there is a concern that the design cost, work cost, cost of components to be replaced, etc. associated with the modification will increase.

[0010] On the one hand, if, from the very beginning of vehicle development, the power consumption specifications of electrical components that may be added later are designed with a large margin in advance, the above-mentioned modification will become unnecessary. However, in that case, components such as the wires, terminals, and fuses of the wire harness connected to the upstream side of the power box will be larger than necessary, so it will be wasteful unless electrical components that actually consume a large current are connected to the downstream side of the power box. As a result, it will lead to an increase in the cost of components such as the wire harness, and the space occupied by components such as the wire harness will increase more than necessary.

[0011] The present invention has been made in view of the above-mentioned circumstances, and its object is to provide an in-vehicle power distribution device that can be easily additionally connected to new electrical components or new functions that are not assumed at the time of design without making components such as wire harnesses larger than necessary.

Means for Solving the Problems

[0012] In order to achieve the above-mentioned object, the in-vehicle power distribution device according to the present invention is characterized by the following (1) to (5). (1) An in-vehicle power source, A main power box to which a plurality of loads can be connected, An upstream wire connecting the output of the in-vehicle power source and the input of the main power box, For each of the plurality of loads connected to the downstream side of the main power box On-off of flowing current A plurality of semiconductor switches that can be individually controlled, A control unit that controls the plurality of semiconductor switches, And is provided with The control unit For each of the plurality of semiconductor switches, when the current flowing through the load connected to the downstream side of the semiconductor switch Obtain the value of the current and the length of time during which current flows through the load, and calculate the total current value, which is the sum of the currents flowing through all the loads, based on the value of the current for each of the plurality of loads, and calculate the energization time length based on the length of the time for each of the plurality of loads. A power control characteristic is prestored, which defines the relationship between time and current value and has a characteristic that the current value gradually decreases as time increases. The total current value is a current value obtained based on the energization time length and the power control characteristic. Approaches the current allowable value in the upstream wire, So that the total current value is limited to be less than or equal to the current allowable value. Controlling the plurality of semiconductor switches so as to adjust power distribution to the plurality of loads according to the priority of each of the plurality of loads connected to the downstream side of the main power box. In-vehicle power distribution device.

[0013] (2) The upstream electric wire is provided with an upstream fuse that limits the current flowing through the upstream electric wire. The current allowable value of the upstream electric wire is determined to be a value smaller than at least one of the smoke generation characteristics of the upstream electric wire and the breaking characteristics of the upstream fuse. The in-vehicle power distribution device according to (1) above.

[0014] (3) The control unit has a data holding unit that holds in advance fuse information representing the breaking characteristics of the upstream fuse. The in-vehicle power distribution device according to (2) above.

[0015] (4) When the control unit approaches the current allowable value in the upstream electric wire, Total current value among the plurality of semiconductor switches, a specific semiconductor switch to which a load with a priority Maintained on is connected. Is relatively low Load To is connected. Perform pulse width modulation control that periodically repeats on-off. If the total current value still approaches the current allowable value in the upstream electric wire even after the execution of the pulse width modulation control, switch off the specific semiconductor switch. The in-vehicle power distribution device according to any one of (1) to (3) above.

[0016] (5) The control unit identifies the priority information of each load connected to the downstream side of the semiconductor switch based on the position of the connector to which each load is connected or information obtained by communication from each load. The in-vehicle power distribution device according to any one of (1) to (4) above.

[0017] According to the in-vehicle power distribution device configured as described in (1) above, even without unnecessarily increasing the size of the wires or the like on the upstream side of the main power supply box, new electrical components or new functions that were not assumed during design can be easily added and connected. For example, when a new electrical component that consumes a large amount of power is connected as a load to the downstream side of the main power supply box, the total load current may increase to the extent that it approaches the current tolerance value of the upstream wire. If nothing is controlled, for example, the fuse may cut off the circuit, or it is also assumed that the upstream wire may overheat abnormally and reach a smoking state. However, since the control unit automatically adjusts the power distribution to a plurality of loads, it is possible to avoid an increase in the total load current. Moreover, since the power distribution is adjusted in consideration of the priorities of each of the plurality of loads actually connected to the downstream side of the main power supply box, it is possible to avoid limiting the functions of the loads with high priority. Therefore, it is not necessary to modify the components such as the wires and fuses on the upstream side of the main power supply box.

[0018] According to the in-vehicle power distribution device configured as described in (2) above, even when a new electrical component that consumes a large amount of power is connected as a load to the downstream side of the main power supply box, the control unit controls the power distribution adjustment so that the total load current does not reach the smoking characteristics of the upstream wire or the cutoff characteristics of the upstream fuse. Therefore, it is possible to prevent the upstream wire from entering a smoking state and also avoid the upstream fuse from cutting off the circuit.

[0019] According to the in-vehicle power distribution device configured as described in (3) above, since the control unit can obtain information on the cutoff characteristics of the upstream fuse from the data holding unit, it is possible to suppress an increase in the total load current so that the upstream fuse does not enter a state of cutting off the circuit.

[0020] According to the in-vehicle power distribution device configured as described in (4) above, the control unit can suppress an increase in the total load current by switching off a specific semiconductor switch connected to the path of a load with a low priority. Also, when the specific semiconductor switch switches to intermittent energization control to limit the energization time, an increase in the total load current can be suppressed.

[0021] According to the in-vehicle power distribution device configured as described in (5) above, even when an unknown electrical component is newly connected as a load downstream of the semiconductor switch, the control unit can easily grasp the information on the priority of the corresponding load.

Effects of the Invention

[0022] According to the in-vehicle power distribution device of the present invention, even without making the wires and the like upstream of the main power box larger than necessary, new electrical components and new functions that were not assumed at the time of design can be easily added and connected. For example, when a new electrical component that consumes a large amount of power is connected as a load downstream of the main power box, the total load current may increase to the extent that it approaches the current allowable value in the upstream wire. If nothing is controlled, for example, the fuse may cut off the circuit, or it is also assumed that the upstream wire may abnormally heat up and reach a smoking state. However, since the control unit automatically adjusts the power distribution to a plurality of loads, it is possible to avoid an increase in the total load current. Moreover, since the power distribution is adjusted in consideration of the priority of each of the plurality of loads actually connected downstream of the main power box, it is possible to avoid the function of the load with a high priority being restricted. Therefore, it is not necessary to perform modifications for replacing components such as the wire and fuse upstream of the main power box.

[0023] As described above, the present invention has been briefly explained. Furthermore, the details of the present invention will be further clarified by reading through the embodiments (hereinafter referred to as "embodiments") for carrying out the invention described below with reference to the accompanying drawings.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0025] Specific embodiments of the present invention will be described below with reference to the respective drawings.

[0026] FIG. 1 is a block diagram showing a configuration example of an in-vehicle power distribution device 100 according to an embodiment of the present invention.

[0027] The in-vehicle power distribution device 100 shown in FIG. 1 is mainly configured by an area ECU 20. This area ECU 20 has a function for managing a specific area predetermined on the vehicle, and has a function of supplying power supply power to loads such as various electrical components connected to the downstream side thereof. Note that the area managed by the area ECU 20 may be assigned to a specific area in the space on the vehicle, or may be assigned to a specific functional group.

[0028] The in-vehicle power supply 10 shown in FIG. 1 corresponds to, for example, a main battery, an alternator, a DC / DC converter, etc. mounted on the vehicle, and functions as a power supply source for the power supply power required by various electrical components mounted on the vehicle. The output voltage of the in-vehicle power supply 10 is, for example, 12 [V], but it may output a voltage such as 48 [V].

[0029] In the example shown in FIG. 1, a plurality of upstream electric wires 11 and 12 are connected to the output of the in-vehicle power supply 10. Further, each of the upstream electric wires 11 and 12 is provided with an upstream fuse 13 and 14, respectively. The upstream fuses 13 and 14 have a function of blowing and cutting off the circuit when a large current exceeding the allowable value flows through the upstream electric wires 11 and 12, respectively. That is, if a large current continues to flow through each of the upstream electric wires 11 and 12 and abnormally generates heat, problems such as smoke generation may occur. Therefore, the upstream fuses 13 and 14 have a function to prevent this in advance.

[0030] The power input terminal 20a of the area ECU 20 is connected to the downstream side of the upstream electric wire 11. Therefore, the power supplied by the in-vehicle power supply 10 is supplied to the area ECU 20 via the upstream fuse 13 and the upstream electric wire 11.

[0031] The area ECU 20 is provided with a plurality of signal input terminals 20b. A plurality of signal lines 51 are connected to these signal input terminals 20b. Therefore, signals from various vehicle sensors, switches, etc. are input to the area ECU 20 via the signal lines 51.

[0032] In addition, the area ECU 20 is provided with a communication terminal 20c. This communication terminal 20c is connected to the vehicle-side communication bus 52. The communication bus 52 is a transmission path of a communication network configured according to a vehicle communication standard such as CAN (Controller Area Network), and enables data communication between various ECUs and other electrical components on the vehicle.

[0033] In addition, on the output side of the area ECU 20, power output terminals 25a, 25b, 25c, ···, power output terminals 26a, 26b, 26c, ···, power output terminals 27a, 27b, ···, and a communication terminal 28 are provided.

[0034] The power output terminals 25a, 25b, 25c, ··· are provided to supply the necessary power for various electrical components belonging to, for example, the engine control system, the control system of the driving motor, the steering system, the braking system, etc., which are necessary for the vehicle to run. Therefore, in the example of FIG. 1, the running system load 31A is connected to the power output terminal 25a, and the running system load 31B is connected to the power output terminal 25b.

[0035] The power output terminals 26a, 26b, 26c, ··· are provided to supply the necessary power for various electrical components of the accessory system that have no direct relation to the vehicle running. For example, lamps such as headlights and winkers, wiper devices, air conditioners, door lock devices, car navigation devices, audio devices, etc. belong to the accessory system. Therefore, in the example of FIG. 1, the accessory system load 32A is connected to the power output terminal 26a, and the accessory system load 32B is connected to the power output terminal 26b.

[0036] On the other hand, the power output terminals 27a, 27b, ···, and the communication terminal 28 are terminals of a reserve system provided in preparation for future function addition. In the example of FIG. 1, a state is shown in which the additional load 33A is connected to the power output terminal 27a and the additional ECU 33B is connected to the power output terminal 27b. However, the additional load 33A and the additional ECU 33B are electrical components that are only assumed to be possible connection targets at the initial design of this vehicle. Therefore, for example, the specifications of the power currents consumed by the additional load 33A and the additional ECU 33B respectively are determined as needed after the vehicle is designed.

[0037] However, it is assumed that the sum of the power currents consumed by the entire load on the downstream side of the area ECU 20 will change significantly before and after the elements of the additional function 40 are connected to the area ECU 20 shown in FIG. 1. This change affects the magnitude of the current flowing through the upstream electric wire 11, and there is a possibility that a large current exceeding the allowable current of the upstream electric wire 11 will flow through the upstream electric wire 11.

[0038] In the case of a general design, when the maximum value of the current flowing through the upstream wire 11 increases, the upstream wire 11 must be changed to a thicker wire in order to increase the allowable current. Also, in accordance with the changes in the allowable current and thickness of the upstream wire 11, the specifications of components such as the upstream fuse 13 and the terminals of each part must also be changed, resulting in the need for large-scale modification.

[0039] On the other hand, there may be a case where the design is such that a margin is provided in the allowable current of the upstream wire 11 in anticipation of an increase in the power supply current newly consumed by the connection of the future additional function 40. In that case, since a margin larger than necessary will be provided compared to the total power supply current actually consumed by the loads connected to the downstream side of the area ECU 20, the upstream wire 11 and the like will become thicker, and the power supply will become larger as a whole.

[0040] In the in-vehicle power distribution device 100 shown in FIG. 1, there is no need to provide an excessive margin in the thickness or the like of the upstream wire 11, and moreover, even when an additional function 40 whose power supply current and other specifications are undetermined at the initial design stage is connected to the area ECU 20, it is possible to prevent the upstream wire 11 from smoking or the like without applying special modification. The area ECU 20 is equipped with a function for that purpose.

[0041] The area ECU 20 includes a microcomputer 21, a communication circuit 22, a switch section 23, and a non-volatile memory 24. Also, in the example of FIG. 1, the switch section 23 includes a first switch section 23a, a second switch section 23b, and a spare switch section 23c. Also, in the switch section 23, the first switch section 23a, the second switch section 23b, and the spare switch section 23c are each equipped with an IPD (Intelligent Power Device) corresponding to the number of loads that can be connected.

[0042] Each IPD incorporates a semiconductor switch (MOS-type FET) that switches the on / off of the current flowing through the load, a gate driver, a current detection function, a protection circuit, and the like.

[0043] In the state shown in FIG. 1, for example, when the uppermost IPD in the first switch section 23a is turned on, a power supply current flows from the power input terminal 20a through the power line 29, the IPD in the first switch section 23a, and the power output terminal 25a to the running system load 31A. Also, when this IPD is turned off, the power supply to the running system load 31A is cut off.

[0044] Therefore, by turning on and off each IPD in the switch section 23, the power supply to a plurality of loads connected downstream of the area ECU 20 can be individually turned on and off. Also, by repeating the on / off operation periodically at a short cycle, it is possible to perform intermittent energization control such as pulse width modulation control (PWM).

[0045] The control input of each IPD in the switch section 23 is connected to the output port of the microcomputer 21, respectively. Also, the current information detected by each IPD in the switch section 23 is input to the input port of the microcomputer 21, respectively. Therefore, the microcomputer 21 can individually grasp the power supply current flowing through each load connected downstream of the area ECU 20. Also, the microcomputer 21 can individually control the on / off of the power supply to each load connected downstream of the area ECU 20.

[0046] Also, although not shown in FIG. 1, connectors are provided at the locations of each power output terminal 25a, 25b, 25c, ···, power output terminal 26a, 26b, 26c, ···, power output terminal 27a, 27b, ··· to enable physical and electrical connection and disconnection. For each electrical component connected to each connector location, the priority regarding power supply is determined in advance. Also, in this example, three types of priorities, "high", "medium", and "low", are defined.

[0047] In this embodiment, as shown in FIG. 1, the priorities of the connectors of the running system loads 31A and 31B are set to "high", the priority of the connector of the auxiliary system load 32A is set to "high", the priority of the connector of the auxiliary system load 32B is set to "low", and the priorities of the connectors of the additional loads 33A and the additional ECU 33B are set to "medium".

[0048] However, for the additional loads 33A and the additional ECU 33B that are to be connected later as the additional function 40, if the specifications including the priority are fixed at the initial design stage, it will be difficult to connect new devices that implement advanced functions. Therefore, the additional ECU 33B is configured to be able to change the assigned priority by communicating with the microcomputer 21 using the communication terminal 28.

[0049] The microcomputer 21 can implement various functions necessary for the control of the area ECU 20 by executing a pre-installed program. For example, the situation can be identified based on the states of various signals input to the signal input terminal 20b, and the on / off control of each load connected to the downstream side of the area ECU 20 can be performed. In addition, the microcomputer 21 can exchange information with other ECUs via the communication circuit 22 and the communication bus 52 as needed.

[0050] The non-volatile memory 24 can hold various predetermined constant data. For example, data representing the specifications of the upstream fuses 13 and 14 connected to the upstream electric wires 11 and 12 (such as 30 [A], 40 [A], etc.), data on the priorities assigned to the connectors on the output side of the area ECU 20, etc. are held in a predetermined storage area on the non-volatile memory 24 in advance.

[0051] FIG. 2(a) and FIG. 2(b) are graphs showing examples of power supply characteristics in a general vehicle and the vehicle of the embodiment, respectively.

[0052] In the in-vehicle power distribution device 100 shown in FIG. 1, the upstream electric wire 11 on the upstream side of the area ECU 20 generates heat due to Joule heat corresponding to the power loss determined by the internal resistance of this electric wire and the current (Iy) passing through this electric wire. Further, when the thickness (cross-sectional area) of the core wire of the electric wire is small, the internal resistance per unit length increases, so the amount of heat generation increases. Therefore, if a large current exceeding the allowable current of the upstream electric wire 11 continues to flow, the temperature may continue to rise and the upstream electric wire 11 may reach a smoking state. To prevent this, when a large current flows, the upstream fuse 13 shuts off the circuit.

[0053] The boundary of the condition for the upstream electric wire 11 to start generating smoke can generally be represented by a curve such as the upstream electric wire smoke generation characteristic C0 shown in FIG. 2(a). That is, when a larger current flows, there is a possibility of reaching the smoking state with only a shorter energization time. Also, when the current continues to flow for a long time, there is a possibility of reaching the smoking state even with an overcurrent slightly larger than the allowable current.

[0054] On the other hand, the characteristics of the upstream fuse 13 inserted in series with the upstream electric wire 11 can be represented by a curve such as the upstream fuse melting characteristic C1 shown in FIG. 2(a). That is, it is designed to adopt a component with a characteristic (C1) in which the upstream fuse 13 melts and shuts off the circuit before the current (Iy) actually flowing through the upstream electric wire 11 approaches the boundary of the curve of the upstream electric wire smoke generation characteristic C0.

[0055] Also, the specifications of the area ECU 20 and the specifications of each load connected to its downstream side are determined in advance so that the total current value Iy flowing through the upstream electric wire 11 does not reach the boundary of the upstream fuse melting characteristic C1 shown in FIG. 2(a). For example, the maximum value of the power supply current flowing through each load is limited, or it is limited so that a large power supply current does not continue to flow for a long time. Therefore, like the characteristic curve of the total current value Iy shown in FIG. 2(a), the actual total current value Iy flowing through the upstream electric wire 11 operates below the boundary of the upstream fuse melting characteristic C1. Therefore, the situation where the upstream fuse 13 melts does not occur.

[0056] However, when designing the thickness of the upstream electric wire 11 and the specifications of the upstream fuse 13 based on the total current value Iy in a situation where the additional function 40 shown in FIG. 1 is not connected, for example, when the additional function 40 is connected, the total current value Iy may reach the upstream fuse blowing characteristic C1. Therefore, the upstream fuse 13 will blow. And since the supply of power to the downstream side of the area ECU 20 stops due to the blowing of the upstream fuse 13, the functions of each load connected to the area ECU 20 also stop.

[0057] Therefore, the area ECU 20 shown in FIG. 1 has a function of controlling based on the power control characteristic C2 shown in FIG. 2(b). As shown in FIG. 2(b), the curve of the power control characteristic C2 is at a position lower than the boundary of the curve of the upstream fuse blowing characteristic C1.

[0058] Actually, the area ECU 20 controls the current on the load side so that the total current value Iy is limited to be equal to or less than the power control characteristic C2 both before and after the additional function 40 is connected. Therefore, the total current value Iy is reduced before the total current value Iy approaches the boundary of the curve of the upstream fuse blowing characteristic C1. Thereby, even when an additional function 40 not assumed at the initial design of the area ECU 20 is connected to the downstream side of the area ECU 20, it is possible to avoid the blowing of the upstream fuse 13.

[0059] FIG. 3 is a flowchart showing an operation example of the area ECU 20 shown in FIG. 1. That is, the microcomputer 21 in the area ECU 20 executes the control of each step in FIG. 3 according to a program. The operation in FIG. 3 will be described below.

[0060] When the power supply of the area ECU is turned on, the microcomputer 21 proceeds from S11 to S12 and acquires fuse specification information D1 representing the characteristics of the upstream fuse 13 (for example, the current specification is 30 [A]) from the information storage unit M01 in the non-volatile memory 24.

[0061] In addition, the information storage unit M02 in the non-volatile memory 24 preliminarily holds a list of fuse blowing characteristics information representing the relationship between the current values and blowing characteristics of fuses with various characteristics.

[0062] Based on the fuse specification information D1 acquired at S12, the microcomputer 21 acquires, at S13, data of the upstream fuse blowing characteristics C1 (see FIG. 2(b)) corresponding to the upstream fuse 13 from the information storage unit M02.

[0063] Based on the upstream fuse blowing characteristics C1 acquired at S13, the microcomputer 21 determines, at S14, data of the power control characteristics C2. As shown in FIG. 2(b), the curve of the power control characteristics C2 is determined such that the current and time are, for example, smaller by a certain value than the upstream fuse blowing characteristics C1.

[0064] For each load connected to the downstream side of the area ECU 20, the microcomputer 21 acquires, at S15, priority information D2 representing its priority. Note that an initial value is assigned in advance to the position of the connector connecting each load for each priority, but the priority can be changed.

[0065] For each load connected to the downstream side of the area ECU 20, the microcomputer 21 acquires, at S16 from each IPD, the energization current value Ix flowing through the IPD in the switch unit 23 that controls its energization.

[0066] For each load connected to the downstream side of the area ECU 20, the microcomputer 21 constantly monitors, at S17, the length of time during which current flows through the IPD that controls its energization as the energization time length Tx.

[0067] The microcomputer 21 calculates the total current value Iy as the sum of the currents flowing through all the loads connected to the downstream side of the area ECU 20, and calculates the energization time length Ty (S18). Here, the total current value Iy corresponds to the current value flowing through the upstream electric wire 11 and the upstream fuse 13.

[0068] The total current value Iy and the energization time length Ty are 0 immediately after the power supply of the area ECU is switched from off to on, and sequentially change stepwise on the graph of FIG. 2(b) as the energization of each load is turned on and off. Further, considering the heat generation and heat dissipation conditions corresponding to the power loss generated in the upstream electric wire 11, an appropriate energization time length Ty is calculated based on the energization time length Tx of each load so as to reflect the actual temperature change of the upstream electric wire 11.

[0069] The microcomputer 21 compares the latest total current value Iy and the energization time length Ty calculated in S18 with the threshold value representing the boundary of the power control characteristic C2 determined in S14 (S19). Then, when the latest total current value Iy and the energization time length Ty approach the power control characteristic C2, the process proceeds to the process of S21.

[0070] The microcomputer 21 is connected to the downstream side of the area ECU20, and for the load with a low priority grasped in S15 among the energized loads, switches off the IPD that controls the energization of the load to cut off the energization (S21).

[0071] On the other hand, when the microcomputer 21 detects from the comparison in S19 that the latest total current value Iy and the energization time length Ty have sufficient margin (the current is small) with respect to the power control characteristic C2, the process proceeds from S22 to S23. In that case, the microcomputer 21 releases the energization cutoff for the load cutoff in S21 in S23.

[0072] By executing the operation shown in FIG. 3, the total current value Iy flowing through the upstream electric wire 11 and the upstream fuse 13 is automatically controlled to be limited below the boundary of the power control characteristic C2 in FIG. 2(b).

[0073] Therefore, even when a new additional function 40 that was not assumed in the initial design of the in-vehicle power distribution device 100 is added and connected to the area ECU 20, the upstream fuse 13 can be prevented from blowing. Moreover, since power supply is cut off only for loads with low priority when the total current value Iy approaches the power control characteristic C2, the functions of loads with high priority can be maintained at all times. In addition, since the design specification of the total current value Iy flowing through the upstream wire 11 and the upstream fuse 13 can be determined without considering the uncertain power supply current flowing through the additional function 40, it is not necessary to thicken the upstream wire 11, and no change is required when the additional function 40 is added. Furthermore, when the total current value Iy is relatively small, power can be supplied to loads with low priority.

[0074] FIG. 4 is a flowchart showing a modified example of the operation of the area ECU 20. The operation shown in FIG. 4 is a modified example of the operation shown in FIG. 3, and only steps S21A and S23A are changed. The operation of the changed part will be described below.

[0075] In the operation of FIG. 4, when the microcomputer 21 determines that the latest total current value Iy and the energization time length Ty are approaching the power control characteristic C2, the process proceeds to the process of S21A. Then, when energizing a load with low priority grasped in S15 among the loads connected to the downstream side of the area ECU 20 and in an energized state, pulse-width modulation control (PWM) is performed by periodically repeating the on / off of the IPD at a short cycle (S21A). That is, the pulse width of the current flowing through the load is limited to control the effective value of the current to be smaller than normal.

[0076] On the other hand, when the microcomputer 21 detects through the comparison in S19 that the latest total current value Iy and the energization time length Ty have sufficient margin (small current) with respect to the power control characteristic C2, the process proceeds from S22 to S23A. In that case, the energization control for the load whose energization control was changed to PWM control in S21A is returned to normal on / off control in S23A.

[0077] When implementing the operation of FIG. 4, since the power supply power supplied to the load with a lower priority is limited when the total current value Iy and the energization time length Ty approach the power control characteristic C2, the function of the load with a lower priority temporarily deteriorates, but the minimum function can always be maintained.

[0078] Note that the operations of FIGS. 3 and 4 may be combined. For example, when the latest total current value Iy and the energization time length Ty approach the power control characteristic C2, first, the control of the load with a lower priority is shifted to PWM control in the same manner as S21A. If the total current value Iy and the energization time length Ty still approach the power control characteristic C2 even with this PWM control, the energization of the corresponding load is completely cut off in the same manner as S21.

[0079] FIG. 5 is a flowchart showing an example of a process for the microcomputer 21 to grasp the priority of the loads. That is, the details of step S15 in FIG. 3 are shown in FIG. 5.

[0080] The microcomputer 21 grasps, in S31, the correspondence between the positions of the respective connectors corresponding to each of the power output terminals 25a, 25b, 25c,..., 26a, 26b, 26c,..., 27a, 27b on the downstream side of the area ECU 20 and the loads connected to those positions.

[0081] In the information storage unit M03 in the non-volatile memory 24, data representing a list of priorities for each connector is previously held. For example, in the priority situation shown in FIG. 1, the priorities assigned to the connectors of the power output terminals 25a, 25b, 26a, 26b, 27a, and 27b are "high", "high", "high", "low", "medium", and "medium", respectively.

[0082] The microcomputer 21 acquires, from the information storage unit M03 of the non-volatile memory 24, priority information D2 representing the priority of the position of the connector to which each load is connected, and grasps the priority (S32).

[0083] In addition, in the case where each load is an ECU having a communication function, communication can be performed between the ECU on the load side and the area ECU 20. For example, since the additional ECU 33B shown in FIG. 1 is connected to the communication terminal 28, it can communicate with the microcomputer 21 via the communication circuit 22.

[0084] When the microcomputer 21 can communicate with each load, it acquires the priority information D2 transmitted by each load at S33. In the present embodiment, the priority information D2 of each load grasped by the microcomputer 21 is overwritten by the information acquired later. Therefore, the priority of the load that cannot communicate is fixed to the priority assigned to the connector position in advance, but in the case of a load that can communicate, the microcomputer 21 can change the priority grasped according to the specifications of the load.

[0085] Among the additional functions 40 shown in FIG. 1, components such as the spare switch section 23c, the power output terminals 27a and 27b, and the communication terminal 28 may be incorporated into the area ECU 20 in advance, or may be incorporated into the area ECU 20 by retrofitting when adding the additional load 33A, the additional ECU 33B, etc.

[0086] As described above, in the in-vehicle power distribution device 100, even when an additional function 40 with a specification not assumed at the initial design is later additionally connected to the area ECU 20, the total current value Iy is controlled based on the power control characteristic C2, and the upstream fuse 13 is prevented from blowing. Therefore, when connecting the additional function 40, there is no need to modify components such as the upstream electric wire 11 and the upstream fuse 13, and easy connection such as plug and play can be realized. In addition, by preventing the upstream fuse 13 from blowing, the power supply to the load with a high priority is always maintained, and the function does not stop, so the reliability can be improved. Moreover, since it is not necessary to have more margin than necessary in the size of components such as the upstream electric wire 11 and the upstream fuse 13, an increase in the size of components such as the upstream electric wire 11 can be avoided.

[0087] Furthermore, the present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. In addition, the material, shape, dimensions, number, arrangement location, etc. of each component in the above-described embodiments are arbitrary as long as the present invention can be achieved, and are not limited.

[0088] Here, the features of the in-vehicle power distribution device according to the above-described embodiments of the present invention are briefly summarized and listed in [1] to [5] below, respectively. [1] An in-vehicle power source (10), a main power supply box (area ECU 20) to which a plurality of loads can be connected, an upstream electric wire (11) connecting between the output of the in-vehicle power source and the input of the main power supply box, a plurality of semiconductor switches (each IPD in the switch unit 23) capable of individually controlling the power supply to each of the plurality of loads connected to the downstream side of the main power supply box, a control unit (microcomputer 21) for controlling the plurality of semiconductor switches, and the control unit collects information on the load current flowing through the load connected to the downstream side of the semiconductor switch for each of the plurality of semiconductor switches (S16), and when at least the sum of the load currents (total current value Iy) approaches the current allowable value (power control characteristic C2) in the upstream electric wire, the control unit adjusts the power distribution to the plurality of loads according to the priority of each of the plurality of loads connected to the downstream side of the main power supply box (S19 to S23), and controls the plurality of semiconductor switches as described above. In-vehicle power distribution device.

[0089] [2] The upstream electric wire includes an upstream fuse (13) for limiting the current flowing through the upstream electric wire, the current allowable value (power control characteristic C2) of the upstream electric wire is determined to be a value smaller than at least one of the smoke generation characteristic (C0) of the upstream electric wire and the cut-off characteristic (upstream fuse blowing characteristic C1) of the upstream fuse (see Fig. 2(b)), The in-vehicle power distribution device according to [1] above.

[0090] [3] The control unit has a data holding unit (non-volatile memory 24, information storage unit M01) that holds in advance fuse information (fuse specification information D1) representing the cutoff characteristics of the upstream fuse. The in-vehicle power distribution device according to [2] above.

[0091] [4] When the sum of the load currents approaches the current allowable value in the upstream electric wire, the control unit switches off a specific semiconductor switch connected to a path of a load with a low priority among the plurality of semiconductor switches (S21), or switches to intermittent energization control so that the specific semiconductor switch limits the energization time (S21A). The in-vehicle power distribution device according to any one of [1] to [3] above.

[0092] [5] The control unit specifies information on the priority of each load connected to the downstream side of the semiconductor switch based on the position of the connector to which each load is connected (S32), or by information acquired through communication from each load (S33). The in-vehicle power distribution device according to any one of [1] to [4] above.

Explanation of Signs

[0093] 10 In-vehicle power supply 11, 12 Upstream electric wire 13, 14 Upstream fuse 20 Area ECU 20a Power input terminal 20b Signal input terminal 20c Communication terminal 21 Microcomputer 22 Communication circuit 23 Switch unit 23a First switch unit 23b Second switch unit 23c Spare switch unit 24 Non-volatile memory 25a, 25b, 25c Power output terminals 26a, 26b, 26c Power output terminals Power output terminals 27a, 27b Communication terminal 28 Power cord 29 Running system loads 31A, 31B Auxiliary system loads 32A, 32B Additional load 33A Additional ECU 33B Additional function 40 Signal line 51 Communication bus 52 In-vehicle power distribution device 100 Upstream wire smoke emission characteristics C0 Upstream fuse melting characteristics C1 Power control characteristics C2 Fuse specification information D1 Priority information D2 Power-on current value Ix Total current value Iy Power-on time duration Tx, Ty Information storage units M01, M02, M03

Claims

1. An in-vehicle power source, a main power box to which a plurality of loads can be connected, an upstream electric wire connecting the output of the in-vehicle power source and the input of the main power box, a plurality of semiconductor switches capable of individually controlling the on / off of the current flowing through each of the plurality of loads connected to the downstream side of the main power box, a control unit for controlling the plurality of semiconductor switches, comprising: the control unit, for each of the plurality of semiconductor switches, obtains the value of the current flowing through the load connected to the downstream side of the semiconductor switch and the length of time during which current flows through the load, and calculates the total current value, which is the sum of the currents flowing through all the loads, based on the value of the current for each of the plurality of loads, and calculates the energization time length based on the length of time for each of the plurality of loads, stores in advance a power control characteristic that defines the relationship between time and current value and has a characteristic that the current value gradually decreases as time increases, when the total current value approaches the current allowable value in the upstream electric wire, which is the current value obtained based on the energization time length and the power control characteristic, controls the plurality of semiconductor switches so as to adjust the power distribution to the plurality of loads according to the priority of each of the plurality of loads connected to the downstream side of the main power box so that the total current value is limited to be equal to or less than the current allowable value, an in-vehicle power distribution device.

2. The upstream electric wire includes an upstream fuse that limits the current flowing through the upstream electric wire, the current allowable value of the upstream electric wire is determined to be a value smaller than at least one of the smoke generation characteristic of the upstream electric wire and the cutoff characteristic of the upstream fuse, The in-vehicle power distribution device according to claim 1.

3. The control unit has a data holding unit that holds in advance fuse information representing the cutoff characteristic of the upstream fuse, The in-vehicle power distribution device according to claim 2.

4. When the total current value approaches the current allowable value in the upstream electric wire, the control unit performs pulse width modulation control that periodically repeats on / off for a specific semiconductor switch connected to a load with a relatively low priority among the plurality of semiconductor switches that are kept on, and if the total current value still approaches the current allowable value in the upstream electric wire after the execution of the pulse width modulation control, switches the specific semiconductor switch off. The in-vehicle power distribution device according to any one of claims 1 to 3.

5. The control unit identifies information on the priority of each load connected to the downstream side of the semiconductor switch based on the position of the connector to which each load is connected or information obtained by communication from each load. The in-vehicle power distribution device according to any one of claims 1 to 4.

Images