JP5170888B2 - Vehicle power supply device and vehicle power supply method - Google Patents

Description

  The present invention relates to a vehicle power supply device, and more particularly to a vehicle power supply device including a semiconductor switch connected between a power supply and a load, and a vehicle power supply method.

  2. Description of the Related Art Conventionally, in a vehicle such as an automobile, power is supplied from a battery (power source) to various electrical components and electronic components (loads) such as an ECU (Electric Control Unit). The supply of power to the load is usually performed via a junction box (electrical connection box).

The main functions of the junction box include power supply to the load, circuit branching, and wire protection. In order to realize the above function, the junction box includes a wiring part including a connector part for branching a circuit and connecting a wire harness, a case, and a fuse and a relay. The fuse has an electric wire protection function that prevents fumes and ignition of the electric wire by cutting off the power supply when the electric wire etc. is short-circuited and the power supply is cut off, and the relay is a power supply according to the state of the vehicle and the load It serves as a switch that supplies and shuts off the power.
In recent years, in vehicles such as automobiles, electronic control has progressed, and the number of ECUs mounted on the vehicle has been increasing. Even when the ignition switch and accessory switch are off when the vehicle is stopped, power is always supplied. The number of electronic components that are needed is increasing. For example, an ECU that controls a door lock system, a security system, and the like needs to be constantly supplied with power even when the vehicle is stopped, and is supplied with power via a fuse.

  Also, the fuse installed in the junction box is placed on standby by removing the fuse upstream of the load that is not used in the storage state during transportation, etc., and shutting off the power to prevent the battery from rising due to the standby current of the load. Some require a reduction in current. For this reason, the junction box is mounted in a position that can be reached by a person in the vehicle. Recently, vehicles such as automobiles have been increasingly demanded for weight reduction for improving fuel efficiency, and wire harnesses and junction boxes that are becoming larger due to vehicle electronics are also required to be lighter.

  As one of means for reducing the weight of the wire harness, there is a method of bringing the branch position of the power source, that is, the position of the junction box in the vicinity of each load and shortening the length of the electric wire after the power source branch. This is to reduce the total cross-sectional area of the wire conductor part and the covering part that will become the wire harness trunk line by delaying the branching of the wire bundle determined by the fuse capacity after power supply branching to the vicinity of the load, and it is a technique that reduces the weight. is there. In order to realize this method, it is necessary to liberalize the mounting position of the joint box, which has been determined by the restriction of replacing fuses and relays. Therefore, a system that can not be realized with a component structure that needs to be replaced by fusing, such as a fuse, can be automatically or remotely operated after detecting an overcurrent and shutting off the power supply and removing the abnormality. Is required. Specifically, for example, there are configurations of a semiconductor switch for constantly supplying power to a load / ECU instead of a fuse, and an abnormal current monitoring system for the purpose of electric wire protection.

However, when the fuse function is made into a semiconductor, that is, when a semiconductor switch for constantly supplying power to the load / ECU and an abnormal current monitor system for electric wire protection are configured, even if the vehicle is stopped The semiconductor switch must be operated to supply power to each ECU, and the drive current and the operating current of the abnormal current monitor system always flow, so that the standby current increases and the battery runs out. There are challenges. In particular, the following two cases are assumed as cases where the standby current needs to be reduced.
(1) In a normal vehicle stop state, such as when the vehicle is left in the parking lot for a short period, for example, overnight.
(2) When the vehicle is transported overseas for a long period of several months, or when the vehicle is in a long-term transport mode such as when the vehicle is displayed at a dealer's store for a long period of time.
When the conventional technique is used, the battery capacity must be increased in order to prevent the battery from rising early due to the standby current, but this is difficult to realize due to space and weight problems.

  In addition, when a fuse is simply replaced with a semiconductor element, a PTC (Positive Temperature Coefficient) element having a self-recovery type overcurrent protection function may be used, but the PTC element has an overcurrent. There is a problem that the current value to be interrupted when flowing changes depending on the ambient temperature of the PTC element, and as a result, an electric wire having a large allowable current value in consideration of the ambient temperature dependence of the interrupting current value. It became necessary to set, and the wire diameter had to be increased. Thereby, there also existed the subject that the weight reduction of a wire harness and by extension, a vehicle was not aimed at enough.

  Conventionally, techniques for reducing standby current are known (see, for example, Patent Documents 1, 2, and 3). In the load drive circuit disclosed in Patent Document 1, a drive switching element disposed between a load and a power supply is provided, and a plurality of control units including a gate drive circuit that performs on / off drive of the drive switching element and a power supply, A current interrupt switch is provided to interrupt dark current.

  Further, in the vehicle battery power supply device path disclosed in Patent Document 2, a power line opening / closing means including a relay is provided on a power line connecting a battery and a load that requires constant power, and an operation signal indicating the start of transportation. Is obtained, the power supply line opening / closing means is opened by the opening / closing control means.

In addition, the battery power supply device path of the vehicle disclosed in Patent Document 3 includes an active mode power supply circuit and a low current consumption mode power supply circuit that outputs a constant voltage from the output terminal with less current consumption than the power supply. When the microcomputer operates in the low current consumption mode, a constant voltage is supplied to the load from the power supply circuit for the low current consumption mode.
JP 2004-248093 A Japanese Patent Laid-Open No. 2003-111264 JP 2006-18409 A

In recent years, vehicles such as automobiles have been required to be lighter for improving fuel efficiency, and the desire for lighter wire harnesses has been increasing.
One way to reduce the weight of the wire harness is to disperse the junction box at the optimal position. To achieve this, however, it is necessary to make the junction box maintenance-free. A means comprising a monitor system can be considered. When this means is used, it is necessary to operate the semiconductor switch to supply power to each ECU even when the vehicle is stopped, and the drive current and the operating current of the abnormal current monitoring system always flow. There is a problem that the standby current increases and the battery runs out. Furthermore, there is a problem that a large-capacity battery must be used in order to prevent the battery from rising early due to an increase in standby current.

  In addition, when a fuse is simply replaced with a semiconductor element, a PTC element having a self-recovery type overcurrent protection function is used. However, a PTC element has a current value that cuts off when an overcurrent flows. However, there is a problem that the temperature fluctuates depending on the ambient temperature of the PTC element, and as a result, the wire diameter must be increased to cope with it. Thereby, there also existed the subject that the weight reduction of a wire harness and by extension was not aimed at enough.

By the way, in the prior art of the above-mentioned patent document 1, since a current cutoff switch is provided between a plurality of control units including a gate drive circuit and a power supply, the dark current is cut off.
While the standby current is reduced, the desired function cannot be maintained. The desired function is the function of the fuse. That is, the semiconductor switch is operated to supply power, and the overcurrent cannot be detected to cut off the power, and the fuse cannot be replaced with a semiconductor element.

  Further, the prior art disclosed in Patent Document 2 has a configuration in which power supply line opening / closing means including a relay is provided on a power supply line that connects a load and a battery, which causes a problem when a semiconductor switch is used instead of the relay. This is not a technique for suppressing an increase in standby current.

  Further, the prior art of Patent Document 3 has a configuration in which two power supply circuits for an active mode and a low current consumption mode are provided, and does not reduce standby current while maintaining a desired function.

  The present invention has been made in view of such conventional problems, and in a vehicle power supply device in which a semiconductor switch is connected between a power source and a load, standby current can be reduced without impairing a desired function. It is a vehicle power supply device and a vehicle power supply method capable of realizing weight reduction of a wire harness while suppressing an increase in battery capacity by performing reduction.

  In order to solve the above-described problem, a vehicle power supply device according to claim 1 is a vehicle power supply device including a semiconductor switch connected between a power source and a load, and the semiconductor switch Connected in parallel, bypassing the semiconductor switch and supplying power from the power source to the load, an overcurrent protection element provided in the bypass circuit, opening and closing of the semiconductor switch and abnormal current And a control unit having a function of detecting, when the first control switching signal is input, the control unit turns off the semiconductor switch and supplies power to the load from the bypass circuit. And

  According to this configuration, when the load of each ECU or the like shifts to the power saving mode when the vehicle is in a stopped state and the vehicle power supply device only needs to supply a smaller current than in the steady state, the first control switching is performed on the control unit. When a signal is input, the control unit turns off the semiconductor switch, cuts off the power supply to the load via the path through the semiconductor switch, and supplies power from the power source to the load via the bypass circuit via the overcurrent protection element. Come to supply. The current for driving the semiconductor relay, the operating current of the abnormal current monitoring system, the current flowing through the control unit, etc. are reduced and the first mode is set. This reduces the current that drives the semiconductor switch, the operating current of the abnormal current monitoring system, and the current that flows to the control unit in a normal vehicle stop state, such as when the vehicle is parked overnight in the parking lot. Power consumption can be reduced and desired functions are not impaired. The desired function is the function of the fuse.

  In a vehicle power supply device in which a semiconductor switch having a relay function and a fuse function for protecting electric wires is connected between a power source and a load, an overcurrent protection element is provided in a bypass circuit connected in parallel to the semiconductor switch. Since this can be realized, the weight of the vehicle can be reduced, there is no need to provide a power supply for the first mode, and the power supply path to the load via the semiconductor switch and the semiconductor switch are connected in parallel. Since no bypass circuit switching device is required, the standby current can be reduced with a simple configuration having a small number of components.

  A power supply device for a vehicle according to a second aspect of the present invention further includes a short circuit connected between one end on the load side of the bypass circuit and the ground, and a switch element provided in the short circuit, When the second control switching signal is input, the control unit turns off the semiconductor switch, turns on the switch element to short-circuit the short-circuit, and connects the bypass circuit and the short-circuit to the bypass circuit. By supplying a short-circuit current, the overcurrent protection element is actuated to be non-conductive, and the power supply to the load is cut off.

  According to this configuration, when the vehicle is transported overseas for a long period of several months or when the vehicle is exhibited in a dealer's store for a long time, when the second control switching signal is input to the control unit, The control unit turns off the semiconductor switch, turns on the switch element, turns on the short circuit, and activates the overcurrent protection element. As a result, power supply to the load via the semiconductor switch is cut off, the bypass circuit is also turned off, and the current flowing from the power supply to the load is in a second mode limited to a minimum level.

For this reason, when the vehicle is transported overseas for a long period of several months, or when the vehicle is exhibited at a dealer's store for a long period of time, the standby current flowing through the load is sufficiently reduced.
For example, when a polymer-based overcurrent protection element is used, the resistance value change from the normal time to the current limit is from the fourth power to the sixth power, so the standby current at this time can be reduced by 50% or more. it can.

  Therefore, in the vehicle power supply device in which the semiconductor switch is connected between the power source and the load, when the vehicle is transported overseas without removing the fuse, or when the vehicle is stopped for a long period of time. The battery can be prevented from running out.

  According to a third aspect of the present invention, there is provided a vehicle power supply device including a plurality of semiconductor switches respectively connected between a power source and a plurality of loads, wherein the overcurrent protection element is provided as one bypass circuit. However, the plurality of semiconductor switches are connected in parallel, and the control unit turns off all of the plurality of semiconductor switches when the first control switching signal is input.

  According to this configuration, when the load of each ECU or the like shifts to the power saving mode when the vehicle is in a stopped state and the vehicle power supply device only needs to supply a smaller current than in the steady state, the first control switching is performed on the control unit. When a signal is input, the control unit turns off all of the plurality of semiconductor switches, cuts off the power supply to the load through the path through each semiconductor switch, and passes the overcurrent protection element from the power source to the plurality of loads. Power is supplied via the bypass circuit. The current for driving the semiconductor relay, the operating current of the abnormal current monitoring system, the current flowing through the control unit, etc. are reduced and the first mode is set.

  Therefore, a normal vehicle stop such as when the vehicle is parked overnight in a parking lot with a simple configuration in which a single bypass circuit provided with an overcurrent protection element is simply connected in parallel to a plurality of semiconductor switches. In this state, the current for driving the semiconductor switch and the current flowing through the operating current control unit of the abnormal current monitoring system are reduced, so that the power consumption can be reduced and the desired function is not impaired. The desired function is the function of the fuse.

  In a vehicular power supply device in which a plurality of semiconductor switches having a relay function and a fuse function for protecting an electric wire are connected between a power source and a load, a bypass circuit connected in parallel to the plurality of semiconductor switches is excessively connected. Since it can be realized by providing a current protection element, it is possible to reduce the weight of the vehicle, there is no need to provide a power supply for the first mode, and there are a plurality of power supply paths to a load via a plurality of semiconductor switches. Since no bypass circuit switching device connected in parallel to the semiconductor switch is required, the standby current can be reduced with a simple configuration having a small number of components.

  According to a fourth aspect of the present invention, there is provided a vehicle power supply device including a plurality of semiconductor switches respectively connected between a power source and a plurality of loads, and the one bypass circuit provided with the overcurrent protection element. Are connected in parallel to the plurality of semiconductor switches, and when the second control switching signal is input, the control unit turns off all the plurality of semiconductor switches and shorts the short circuit. It is characterized by being in a state.

  According to this configuration, when the vehicle is transported overseas for a long period of several months or when the vehicle is exhibited in a dealer's store for a long time, when the second control switching signal is input to the control unit, The control unit turns off all of the plurality of semiconductor switches and puts the short circuit into a short circuit state. As a result, the power supply to the load through each of the plurality of semiconductor switches is cut off, and overcurrent flows to the overcurrent protection element through the bypass circuit and the short circuit, and the overcurrent protection element is in a non-conductive state due to a characteristic change. Thus, the current flowing from the power source to the plurality of loads via the overcurrent protection element is limited to a minimum level. Therefore, by simply connecting one bypass circuit with an overcurrent protection element to a plurality of semiconductor switches in parallel, the vehicle can be transported overseas or stopped for a long period of time. In this case, the standby current flowing through each load is sufficiently reduced.

  For example, when a polymer-based overcurrent protection element is used, the resistance value change from the normal time to the current limit is from the fourth power to the sixth power, so the standby current at this time can be reduced by 50% or more. it can.

  Therefore, in a vehicle power supply apparatus in which a plurality of semiconductor switches are connected between a power source and a load, when the vehicle is transported overseas without removing the fuse, the vehicle is stopped for a long period of time. In this case, the battery can be prevented from running out.

  A power supply method for a vehicle according to a fifth aspect of the present invention is a vehicle power supply method including a semiconductor switch connected between a power source and a load. In a steady mode, the power source is supplied from the power source to the load. When the first control switching signal is input, the semiconductor switch is turned off and an overcurrent provided in a bypass circuit connected in parallel with the semiconductor switch Power is supplied from the power source to the load via a protective element.

  According to this configuration, when the first control switching signal is input, the control unit turns off the semiconductor switch, so that power supply to the load on the path through the semiconductor switch is interrupted. As a result, power is supplied from the power source to the load via the overcurrent protection element via the bypass circuit, and the current related to the control of the semiconductor relay becomes the first mode smaller than the current in the steady mode. Thereby, in a normal vehicle stop state such as when the vehicle is parked overnight in the parking lot, the current flowing to the control unit or the like is reduced, and power consumption can be reduced.

  Such a first mode is connected in parallel to a semiconductor switch in a vehicle power supply device in which a semiconductor switch having a relay function and a fuse function for protecting an electric wire is connected between a power source and a load. This can be realized by providing an overcurrent protection element in the bypass circuit, thus reducing the weight of the vehicle, eliminating the need for a special power supply for the first mode, and reducing standby current with a simple configuration with a small number of components. Can be reduced.

  According to a sixth aspect of the present invention, in the vehicle power supply method, when the second control switching signal is input, the semiconductor switch is turned off, and one end of the bypass circuit on the load side is grounded. By turning on the switch element provided in the short circuit connected in between and generating a short circuit current in the bypass circuit and the short circuit, the overcurrent protection element is made non-conductive, so that the load The power supply to is cut off.

  According to this configuration, when the vehicle is transported overseas for a long period of several months or in the second mode in which the vehicle is exhibited at the dealer's store for a long time, the control unit turns off the semiconductor switch and Make the short circuit short. As a result, power supply to the load via the semiconductor switch is cut off, and a short-circuit current flows to the overcurrent protection element via the bypass circuit and the short circuit, and the overcurrent protection element changes its characteristics and becomes non-conductive. The current flowing from the power source to the load via the overcurrent protection element is limited to a minimum level.

  For this reason, when the vehicle is transported overseas for a long period of several months, or when the vehicle is exhibited at a dealer's store for a long period of time, the standby current flowing through the load is sufficiently reduced. Therefore, in a vehicle power supply device in which a semiconductor switch is connected between a power source and a load, when the vehicle is transported overseas with a simple configuration with a small number of parts, the vehicle is stopped for a long period of time. It is possible to suppress the battery from running up.

  In the vehicle power supply method according to the seventh aspect of the invention, the overcurrent protection element is a PTC element. When the switch element is turned on and the short circuit is short-circuited, a short-circuit current is generated in the PTC element. The PTC element is caused to flow to a trip state.

According to this configuration, by using the PTC element as the overcurrent protection element, excellent characteristics such as dark current characteristics and current interruption characteristics can be realized. Here, the “trip state” refers to an electric resistance depending on temperature. This means that a PTC element having a positive temperature characteristic in which increases is in a high resistance state.

  According to the present invention, by making the fuse function semiconductor, it is possible to bring the power supply device to the branch position of the power supply, and it is possible to realize the weight reduction of the wire harness, maintenance-free, etc. Standby current, which is a problem when using a switch, can be reduced with a simple configuration with a small number of components.

  Also, in the first mode, the current consumption of each ECU, etc. is reduced when the vehicle is stopped. The abnormality determination threshold value can be set low enough and the enlargement of the electric wire can be suppressed.

  Next, each embodiment of the present invention will be described with reference to the drawings. In the description of each embodiment, similarly, the same reference numerals are given to the portions, and the duplicate description is omitted.

Further, in the present embodiment, the case where a PTC element is used as the overcurrent protection element will be described. However, the overcurrent protection element is not limited to the PTC element, and may have a function of cutting off current when an overcurrent flows. If applicable.
(First embodiment)
A vehicle power supply device according to a first embodiment of the present invention will be described with reference to FIGS.

  A vehicle power supply device 1 shown in FIG. 1 is mounted on a vehicle such as an automobile, and includes a semiconductor switch 4 connected between a power source (battery) 2 and an ECU 3 as a load. The semiconductor switch 4 is composed of a semiconductor element such as an FET (field effect transistor).

  Further, as shown in FIG. 1, the vehicle power supply device 1 is connected in parallel to the semiconductor switch control unit 5 for turning on and off the semiconductor switch 4 and the semiconductor switch 4, and bypasses the semiconductor switch 4 to supply power 2. A bypass circuit 6 that supplies power from the ECU 3 to the ECU 3, a PTC element 7 provided in the bypass circuit 6, and a controller 8 that opens and closes the semiconductor switch 4. When the power saving mode signal as the first control switching signal is input, the control unit 8 drives the semiconductor switch control unit 5 to turn off the semiconductor switch 4.

  The control unit 8 includes a CPU 9 and a ROM and a RAM (not shown). When the power saving mode signal is input, the CPU 9 drives the semiconductor switch control unit 5 according to the power saving mode control program stored in the ROM to turn off the semiconductor switch 4.

  The power saving mode signal is transmitted by CAN (Controller Area Network) communication from any one of a plurality of ECUs including the ECU 3, for example, and is received by the control unit 8. Alternatively, the power saving mode signal is output from the ECU 3 to the control unit 8 via a signal line (not shown) when a predetermined time elapses from when the ignition switch is turned off by a timer or the like of the ECU 3 itself.

  Further, in the vehicle power supply device 1, a short circuit 10 that causes a short circuit current to flow through the PTC element 7 to bring the PTC element 7 into a trip state is connected between one end of the bypass circuit 6 on the load side and the ground. In this short circuit 10, a PTC trip switch element 11 is arranged between one end of the bypass circuit 6 on the load side and the ground, and the PTC trip switch element 11 itself is composed of a semiconductor element such as an FET. The vehicle power supply device 1 further includes a switch element control unit 12 that turns on and off the PTC trip switch element 11.

  When the transport / long-term neglect mode signal as the second control switching signal is input, the control unit 8 drives the semiconductor switch control unit 5 by the transport / long-term neglect mode control program stored in the ROM to The switch 4 is turned off and the switch element control unit 12 is driven to turn on the PTC trip switch element 11. For example, the transport / long-term leaving mode signal is transmitted from any one of a plurality of ECUs including the ECU 3 by CAN communication, and this signal is received by the control unit 8. Alternatively, the transportation / long-term leaving mode signal is input to the control unit 8 when a transportation mode switch (not shown) is operated during transportation of the vehicle or when leaving the vehicle for a long time. .

In FIG. 1, reference numeral “14” denotes a connector. Reference numeral “16” denotes a diode.
Next, the operation of the vehicular power supply apparatus 1 having the above configuration will be described with reference to FIG.

FIG. 2 shows a voltage (V _{ECU_B} ) supplied to the ECU 3 and a load flowing in the ECU 3 in each mode of the steady mode, the power saving mode as the first mode, and the transportation / long-term leaving mode as the second mode. It is explanatory drawing which shows the relationship of an electric current ( _ILoad ).

The operation in each mode will be described with reference to FIG.
First, in a steady mode such as when the IG switch is turned on, the voltage from the power source 2 is supplied to the ECU 3 via the semiconductor switch 4, and the voltage in this state is indicated by Va. At this time, the current flowing through the ECU is Ia.

  At this time, no current flows through the bypass circuit 6 provided in parallel with the semiconductor switch. The reason is described below. The voltage applied to both ends of the semiconductor switch when the semiconductor switch is on is represented by the product of the on-resistance of the semiconductor switch and the energization current. The on-resistance of the semiconductor switch is about 1 to 10 mΩ at room temperature, and the voltage drop is about 0.1 V even when about 10 A flows. On the other hand, in a bypass circuit including a PTC element, a diode is inserted in series in order to prevent a power supply from wrapping around. As a characteristic of the diode, a forward current does not flow unless the forward voltage is about 0.6V. It has become. Therefore, when the semiconductor switch is on, the voltage applied to the bypass circuit is sufficiently lower than the voltage for turning on the diode, and thus the bypass circuit is not energized.

  In the steady mode, when an abnormal current or the like occurs due to a short circuit in the electric wire between the power source 2 and the ECU 3, the abnormal current is detected by the control unit 8 or the like, and the semiconductor switch control unit 5 is driven to operate the semiconductor. The switch 4 is turned off to protect the electric wire.

  Next, when a power saving mode signal as a first control switching signal is input to the control unit 8 from the ECU 3 or the like, the control unit 8 drives the semiconductor switch control unit 5 to turn off the semiconductor switch 4. . By controlling in this way, the supply of current to the ECU 3 is performed via the bypass circuit 6.

  Accordingly, since the voltage supplied to the ECU 3 is lowered by the voltage drop due to the diode, a voltage slightly lower than Va is supplied. On the other hand, since the ECU 3 is in a standby state, the current becomes a very small current Ib as compared with the current value Ia in the steady mode.

  In the power saving mode, when an abnormal current is generated due to a short circuit in the electric wire between the power source 2 and the ECU 3, the abnormal current flows through the PTC element installed in the bypass circuit, thereby generating heat instantaneously and increasing the temperature. As a result, the electrical resistance of the PTC itself is increased, the current is instantaneously interrupted, and the wire can be protected. This is a so-called trip state.

Next, when a transport / long-term leaving mode signal as a second control switching signal is input from the ECU 3 or the like to the control unit 8, the control unit 8 drives the semiconductor switch control unit 5 to turn off the semiconductor switch 4. In addition, the switch element control unit 12 is driven to turn on the PTC trip switch element 11. By controlling in this way, the short circuit 10 is short-circuited, and a short-circuit current flows to the short circuit 10 from the power supply 2 through the bypass circuit 6. However, when a short-circuit current flows through the PTC element installed in the bypass circuit 6, heat is generated instantaneously, the electrical resistance of the PTC itself increases, and the current is interrupted instantaneously. Therefore, it is possible to reduce the standby current generated in the ECU 3. At this time, the voltage supplied to the ECU 3 is interrupted by the trip state of the PTC element. On the other hand, the current becomes a trip state and becomes a current value Ic limited to several mA.
According to 1st Embodiment which has the above structure, there exist the following effects.

  When the power saving mode signal is input to the control unit 8, the CPU 9 of the control unit 8 outputs a semiconductor switch off signal to the semiconductor switch control unit 5 to turn off the semiconductor switch 4. The power supply to the ECU 3 on the route is interrupted. As a result, power is supplied from the power source 2 to the ECU 3 via the PTC element 7 via the bypass circuit 6, and the current that drives the semiconductor relay, the operating current of the abnormal current monitoring system, and the current that flows to the control unit, etc. The power saving mode becomes smaller than the load current in the steady mode. In a normal vehicle stop state, such as when the vehicle is parked overnight in the parking lot, the current flowing through the control unit or the like is reduced, and power consumption can be reduced.

  In such a power saving mode, in the vehicle power supply device 1 in which the semiconductor switch 4 having the relay function and the fuse function for protecting the electric wire is connected between the power source 2 and the ECU 3, the semiconductor switch 4 This can be realized by providing the PTC element 7 in the bypass circuit 6 connected in parallel to the circuit, so that a standby current equivalent to that of a conventional fuse can be achieved, a semiconductor fuse function can be realized, and the power supply device is maintenance-free. Layout is free and the weight of the harness can be reduced. Furthermore, it is not necessary to provide a power supply for the power saving mode, and the standby current can be reduced with a simple configuration with a small number of parts.

  When the vehicle is transported overseas for a long period of several months or when the vehicle is displayed at a dealer's store for a long period of time, if the transport / long-term neglect mode signal is input to the control unit 8, The CPU 9 outputs a semiconductor switch off signal to the semiconductor switch control unit 5 to turn off the semiconductor switch 4 and outputs a PTC trip switch element on signal to the switch element control unit 12. As a result, the semiconductor switch control unit 5 turns off the semiconductor switch 4, so that the power supply from the power source 2 to the ECU 3 on the path through the semiconductor switch 4 is cut off. At the same time, the switch element control unit 12 turns on the PTC trip switch element 11. As a result, power supply to the ECU 3 via the semiconductor switch 4 is cut off, and a short-circuit current flows to the PTC element 7 via the bypass circuit 6 and the PTC trip switch element 11, and the temperature of the PTC element 7 rises. The PTC element 7 is in a trip state. For this reason, the current flowing from the power source 2 to the ECU 3 through the PTC element is in a transportation / long-term leaving mode limited to a minute level.

  Such a trip state (transportation / long-term leaving mode) is maintained while the semiconductor switch 4 is turned off. For this reason, when the vehicle is transported overseas for a long period of several months or when the vehicle is exhibited at a dealer's store for a long period of time, the standby current flowing through the ECU 3 is sufficiently reduced. The standby current at this time can be reduced by 50% or more.

  Therefore, in the vehicular power supply device 1 in which the semiconductor switch 4 is connected between the power source 2 and the ECU 3, the vehicle is transported overseas for a long period of time with a simple configuration with a small number of parts. The battery can be prevented from running out when the vehicle is stopped.

Next, a vehicle power supply device 1A according to a second embodiment of the present invention will be described with reference to FIG.
This vehicle power supply device 1 </ b> A includes a plurality of semiconductor switches 4 ₁ to 4 ₃ respectively connected between a power source 2 and a plurality of ECUs (a plurality of loads) 3 _{1 to} 3 ₃ . These ECU 3 ₁ to 3 _3, for example, the necessary ECU is constant power supply, a ECU which controls the door lock system and the security system or the like.

Moreover, in this vehicle power supply device 1A, one bypass circuit 6 provided with the PTC element 7 is connected in parallel to the plurality of semiconductor switches 4 ₁ to 4 ₃ , and the CPU 9A of the control unit 8A When a power saving mode signal as one control switching signal is input, all the plurality of semiconductor switches 4 ₁ to 4 ₃ are turned off.

In the vehicle power supply device 1A, the CPU 9A of the control unit 8A turns off all of the plurality of semiconductor switches 4 ₁ to 4 _{3 when} the transport / long-term leaving mode signal as the second control switching signal is input. At the same time, the PTC trip switch element 11 of the short circuit 10 is turned on.

Note that the vehicle power supply device 1 </ b> A shown in FIG. 3 is accommodated in a junction box (electrical connection box) 20. Further, in FIG. 5, reference numerals “16 ₁ ” to “16 ₃ ” are diodes, and reference numeral “21” is an interface circuit.

  According to 2nd Embodiment which has such a structure, in addition to the effect which the said 1st Embodiment show | plays, there exist the following effects.

· When the power saving mode signal to the CPU 9A of the control unit 8A is input, CPU 9A is to output the semiconductor switch-off signal to a plurality of semiconductor switch controller ₅ 1 to 5 _3, a plurality of semiconductor switches ₄₁ to _Since all _three are turned off, power supply to the ECUs 3 ₁ to ₃ 3 through the paths through the semiconductor switches 4 ₁ to 4 ₃ is cut off. Thus, now the power supply is made respectively via the bypass circuit 6 via the PTC element 7 from the power source 2 to a plurality of ECU 3 ₁ to 3 _3, the operating current of the current and the abnormal current monitor system for driving a semiconductor relay, The current flowing through the control unit or the like becomes a power saving mode smaller than the current consumption in the steady mode. Accordingly, as in the case where the vehicle is stopped overnight in the parking lot with a simple configuration in which one bypass circuit 6 provided with the PTC element 7 is simply connected in parallel to the plurality of semiconductor switches 4 ₁ to 4 _3. It is possible to reduce standby current flowing through a plurality of loads in a normal vehicle stop state.

· When transporting long-term standing mode signal is input to the CPU 9A of the control unit 8A, CPU 9A is to output the semiconductor switch-off signal to a plurality of semiconductor switch controller ₅ 1 to 5 _3, a plurality of semiconductor switches _{4 1} ~ 43 Turn all ₃ off. At the same time, the CPU 9A outputs a PTC trip switch element ON signal to the switch element control unit 12 to turn on the PTC trip switch element 11.

As a result, the power supply to the plurality of ECUs 3 _{1 to} 3 ₃ through the plurality of semiconductor switches 4 ₁ to 4 ₃ is cut off, and the PTC element 7 is short-circuited via the bypass circuit 6 and the PTC trip switch element 11. A current flows, the temperature of the PTC element 7 rises, and the PTC element 7 enters a trip state. Thus, the current flowing through the PTC element 7 from the power source 2 to a plurality of ECU 3 ₁ to 3 ₃ are each limited to a very small level. Therefore, a simple configuration in which one bypass circuit 6 provided with the PTC element 7 is connected in parallel to the plurality of semiconductor switches 4 ₁ to 4 ₃ makes it possible to transport the vehicle overseas or for a long time. if allowed to stop over, it can sufficiently reduce the standby current flowing through each ECU 3 ₁ to 3 _3, it is possible to prevent battery exhaustion.

  In the first embodiment, the semiconductor switch control unit 5, the control unit 8, and the switch element control unit 12 are set as one control unit, and the CPU in the control unit performs the same control as the CPU 9 of the control unit 8. The present invention is also applicable to a configuration that is implemented.

The block diagram which shows schematic structure of the vehicle power supply device which concerns on 1st Embodiment of this invention. Explanatory drawing which shows the relationship between the voltage (V _{ECU_B} ) supplied to the ECU and the load current (I _Load ) flowing through the ECU in each mode of the steady mode, the power saving mode and the transportation / long-term leaving mode. The block diagram which shows schematic structure of the vehicle power supply device which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A: Vehicle power supply device 2: Power sources 3, 3 _{1 to} 3 ₃ : ECU
4, 4 ₁ to 4 ₃ : Semiconductor switch 5, 5 _{1 to} 5 ₃ : Semiconductor switch control unit 6: Bypass circuit 7: PTC element 8 and 8 A: Control unit 10: Short circuit 11: Switch element for PTC trip 12: Switch Element control unit 15, 15 ₁ to 15 ₃ : Electric wire

Claims (7)

A vehicle power supply device comprising a semiconductor switch connected between a power source and a load,
A bypass circuit connected in parallel to the semiconductor switch, bypassing the semiconductor switch and supplying power from the power source to the load;
An overcurrent protection element provided in the bypass circuit;
A controller having a function of detecting opening and closing of the semiconductor switch and abnormal current,
When the first control switching signal is input, the control unit turns off the semiconductor switch and supplies power to the load from the bypass circuit. A short circuit connected between one end of the bypass circuit on the load side and the ground;
Further comprising a switch element provided in the short circuit,
When the second control switching signal is input, the control unit turns off the semiconductor switch, turns on the switch element, places the short circuit in a short circuit state, the bypass circuit, and the short circuit The vehicle power supply device according to claim 1, wherein a power supply to the load is cut off by causing the overcurrent protection element to be non-conductive by generating a short-circuit current.   A plurality of semiconductor switches each connected between a power source and a plurality of loads, and one bypass circuit provided with the overcurrent protection element is connected in parallel to the plurality of semiconductor switches, 2. The vehicle power supply device according to claim 1, wherein when the first control switching signal is input, the control unit turns off all of the plurality of semiconductor switches.   A plurality of semiconductor switches each connected between a power source and a plurality of loads, and one bypass circuit provided with the overcurrent protection element is connected in parallel to the plurality of semiconductor switches, When the second control switching signal is input, the control unit turns off all of the plurality of semiconductor switches and turns on the switch elements to put the short circuit in a short circuit state. The vehicle power supply device according to claim 2. A vehicle power supply method including a semiconductor switch connected between a power source and a load,
In the steady mode, the power supply to the load from the power supply and the interruption are performed by the semiconductor switch,
When the first control switching signal is input, the semiconductor switch is turned off, and power is supplied from the power source to the load via an overcurrent protection element provided in a bypass circuit connected in parallel with the semiconductor switch. A method for supplying power to a vehicle.   When the second control switching signal is input, the semiconductor switch is turned off, and the switch element provided in the short circuit connected between one end of the bypass circuit on the load side and the ground is turned on. The power supply to the load is cut off by causing the overcurrent protection element to be non-conductive by generating a short circuit current in the bypass circuit and the short circuit. The vehicle power supply method according to claim 5.   The overcurrent protection element is a PTC element, and when the switch element is turned on and the short circuit is short-circuited, an abnormal current flows through the PTC element, causing the PTC element to trip. The vehicle power supply device according to claim 6.

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