JP2014069704A - Vehicle power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle power supply circuit for achieving a circuit configuration that suppresses noise entrained in noise entrainment load.SOLUTION: The vehicle power supply circuit includes: a first conductive path W1 whose one end is coupled to a first load 10 for generating noise and the other end is coupled to a battery 30; and a second conductive path W2 whose one end is coupled to a second load 20 for entraining noise and the other end is coupled to the battery 30.

Description

  The present invention relates to a vehicle power supply circuit that supplies power to various loads in a vehicle.

  Patent Document 1 discloses a vehicle power supply circuit having a structure in which noise protection circuits are integrated on the upstream side. The vehicle power supply circuit of Patent Document 1 divides the system according to the characteristics of the connected load, and performs noise protection by providing an appropriate noise protection circuit for each divided system.

Japanese Patent No. 4947127

  By the way, the load connected to the vehicle power supply circuit is a load that easily generates noise (hereinafter referred to as a noise generating load) and a load that easily attracts the generated noise (hereinafter referred to as a noise pulling load). It can be roughly divided into two. Here, the noise pull-in load refers to a load in which noise easily propagates toward itself. The degree to which noise is drawn is determined mainly by the magnitude of the internal resistance of the load. A load with a small internal resistance tends to attract noise. Examples of the noise generating load include an ignition device (ignition), a fuel injection device (injection), and a wiper. Examples of the noise pulling load include an electronic control unit (ECU), a high mount stop lamp, and a seat heater.

  When the load is roughly classified according to the noise generation load and the noise pull-in load, one aspect of the vehicle power supply circuit of Patent Document 1 reads that the noise propagating in the conductive path toward the noise pull-in load is blocked by the noise protection circuit. be able to. Although it is effective to use a noise protection circuit to block noise drawn into the noise pull-in load as in the vehicle power supply circuit of Patent Document 1, a circuit configuration that suppresses noise being drawn into the noise pull-in load is realized. It is also important to do.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a vehicle power supply circuit that realizes a circuit configuration that suppresses noise from being drawn into a noise pulling load.

In order to achieve the above-described object, a vehicle power supply circuit according to the present invention is characterized by the following (1) to (5).
(1) a first conductive path having one end connected to a first load that generates noise and the other end connected to a battery;
A second conductive path having one end connected to a second load that draws noise and the other end connected to the battery;
Be provided.
(2) a first conductive path having one end connected to a first load that generates noise;
A second conductive path connected to a second load having one end drawing noise;
A third conductive path having one end connected to the battery and the other end connected to the other end of the first conductive path and the other end of the second conductive path;
With
The line resistance when viewing the second load from the other end of the second conductive path is larger than the line resistance when viewing the battery from the other end of the third conductive path.
about.
(3) A vehicle power supply circuit configured as described in (2) above,
The second conductive path has a line length longer than that of the third conductive path.
about.
(4) A vehicle power supply circuit having any one of the constitutions (1) to (3),
The first conductive path is connected to a plurality of the first loads.
about.
(5) A vehicle power supply circuit having any one of the constitutions (1) to (4),
The second conductive path constitutes a part of a power circuit in which a part thereof is accommodated in a power distributor.
about.

According to the vehicle power supply circuit having the configuration (1), it is possible to suppress the noise from being drawn into the second load that is the noise drawing load.
According to the vehicle power supply circuit having the configuration (2), it is possible to suppress noise from being drawn into the second load that is a noise drawing load.
According to the vehicle power supply circuit having the configuration of (3) above, when the first conductive path and the second conductive path have the same resistance value per unit length, the other of the second conductive path The line resistance when the second load is viewed from the end is larger than the line resistance when the battery is viewed from the other end of the third conductive path. For this reason, it can suppress that noise is drawn into the 2nd load which is a noise drawing load.
According to the vehicle power supply circuit having the configuration (4), the conductive paths connected to the first load, which is a noise generating load, are collected as the first conductive path. The first conductive path is provided as a bundle of sub-harnesses constituting the wire harness. Noise is drawn into the second load, which is a noise pulling load, by a simple wire harness configuration in which the conductive paths connected to the first load are collected as a bundle of sub-harnesses and the sub-harnesses are connected to the battery. A circuit configuration that suppresses this can be realized.
According to the vehicle power supply circuit having the configuration of (5) above, even when the battery and the second load that is the noise pulling load are connected using the power divider used in the past, the noise pulling load is used. It is possible to realize a circuit configuration that suppresses noise from being drawn into the second load.

  According to the vehicle power supply circuit of the present invention, it is possible to realize a circuit configuration that suppresses noise from being drawn into a noise pulling load.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a circuit diagram of a vehicle power supply circuit according to a first embodiment of the present invention. FIG. 2 is a diagram showing an equivalent circuit of the vehicle power supply circuit according to the first embodiment of the present invention. FIG. 3 is a circuit diagram of a vehicle power supply circuit as a comparative example. FIG. 4 is a diagram showing an equivalent circuit of a vehicle power supply circuit as a comparative example. FIG. 5 is a diagram showing an equivalent circuit of the vehicle power supply circuit according to the second embodiment of the present invention. FIG. 6 is a diagram showing an equivalent circuit of the vehicle power supply circuit according to the second embodiment of the present invention.

  Specific embodiments relating to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a circuit diagram of a vehicle power supply circuit according to a first embodiment of the present invention. FIG. 2 is a diagram showing an equivalent circuit of the vehicle power supply circuit according to the first embodiment of the present invention. Hereinafter, with reference to FIG.1 and FIG.2, the circuit structure of the vehicle power supply circuit which concerns on 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the vehicle power supply circuit according to the first embodiment of the present invention is a circuit that supplies an output voltage output from a battery 30 to a noise generating load 10 and a noise pulling load 20. In order to supply a voltage to the noise generation load 10 and the noise pull-in load 20, the vehicle power supply circuit according to the first embodiment of the present invention includes a connection between the noise generation load 10 and the battery 30 and a noise pull-in load 20 and the battery 30. A first conductive path W1 and a second conductive path W2 that are electrically connected are provided. Furthermore, the vehicle power supply circuit according to the first embodiment of the present invention accommodates a power supply circuit, and a relay box (R / B) 40 in which a part of the first conductive path W1 constitutes a part of the power supply circuit. A junction box (J / B) 50 that houses the power supply circuit and a part of the second conductive path W2 forms a part of the power supply circuit, and a fuse unit 60 that is directly connected to the terminal of the battery 30. And. R / B 40 and J / B 50 are power distributors having a function of distributing power. In the present embodiment, a case where R / B and J / B are used as the power distributor will be described, but R / B and J / B can be replaced by various power distributors.

  The first conductive path W1 includes a power line W11 having one end connected to a fuel injection control device (INJ) 101 that is one of the noise generation loads 10, and an ignition device (IGN) that is one of the noise generation loads 10. A power line W12 having one end connected to 102, and a power line having one end connected to a fuel injection device (EFI) 103 that is one of the noise generating loads 10 and injects fuel together with ignition by an ignition plug of the ignition device 102 Branches to R13 at W13. On the other hand, the other end of the first conductive path W <b> 1 is connected to a bus bar located on the input terminal side of the fuse in the fuse unit 60. By connecting in this way, the noise generating load 10 is connected to the battery 30. The connection point between the other end of the first conductive path W1 and the bus bar located on the input terminal side of the fuse is referred to as P, and from one end of the power supply lines W11, W12, W13 connected to the noise generating load 10 to the connection point P. Is defined as a first conductive path W1.

  The R / B 40 includes a relay 401, a fuse 402, and a fuse 403. The relay 401 is provided on the first conductive path W1 that is not branched, and the switch is turned on by a current that is energized when the ignition device 102 is ignited. The fuse 402 is provided on the power supply line W11 and the power supply line W12. The fuse 403 is provided on the power supply line W13.

  One end of the second conductive path W2 is connected to an airbag electronic control unit (A / B ECU) 20 that is one of the noise drawing loads, and the other end is located on the fuse output terminal side in the fuse unit 60. It has a power line connected to the bus bar. By connecting in this way, the noise pulling load 20 is connected to the battery 30. A section from one end of the power supply line connected to the noise pulling load 20 to the connection point P described above is defined as a second conductive path W2. In the present embodiment, a description will be given of a mode in which only the A / B ECU 20 is cited as the noise pull-in load 20, but in addition to the A / B ECU 20, a high-mount stop lamp, a seat heater, and the like are used as the noise pull-in load 20. However, the present invention can be applied. When a plurality of noise pulling loads 20 are connected to the battery 30, the second conductive path W2 is branched at the J / B 50, and each branched conductive path is laid in the section to the corresponding noise pulling load 20. .

  The J / B 50 includes a relay 501 and a fuse 502. The relay 501 is provided on the second conductive path W2, and the switch is turned on by a current that is energized when the ignition device 102 is ignited. The fuse 502 is provided in the second conductive path W2.

  The fuse unit 60 includes a fuse provided with an input terminal and an output terminal with a fusible member interposed therebetween, and a bus bar to which the fuse is fixed. In the fuse unit 60, the input terminal of the fuse is connected to the power supply terminal of the battery 30 via the bus bar, the input terminal of the fuse is connected to the other end of the first conductive path W1 via the bus bar, and the second An output terminal of the fuse is connected to the other end of the conductive path W2 via a bus bar. In the bus bar of the fuse unit 60, a connection point P between the other end of the first conductive path W1 and the other end of the second conductive path is formed. Hereinafter, a section from the connection point P to the power supply terminal of the battery 30 in the bus bar of the fuse unit 60 is defined as a third conductive path W3.

  In the vehicle power supply circuit according to the first embodiment of the present invention, the noise generation load 10 and the noise pull-in load 20 are the first conductive path W1, the second conductive path W2, R / B 40, J / B 50, and the fuse. Electric power is supplied from the battery 30 via the unit 60.

  Next, a vehicle power supply circuit according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 shows only the configuration that affects the propagation of noise generated from the noise generating load 10 in the circuit diagram shown in FIG. 1, that is, the noise generating load 10, the noise pulling load 20, the battery 30, and the fuse unit 60. And an equivalent circuit of a circuit configuration constituted by those configurations is described.

  In order to explain more clearly that the vehicle power supply circuit according to the first embodiment of the present invention suppresses noise drawn into the noise pull-in load 20, first, a vehicle power supply circuit as a comparative example will be described with reference to FIG. This will be described below with reference to FIG. FIG. 3 is a circuit diagram of a vehicle power supply circuit as a comparative example. FIG. 4 is a diagram showing an equivalent circuit of a vehicle power supply circuit as a comparative example. In FIGS. 3 and 4, the same reference numerals are assigned to the components common to the components described in FIGS.

  The vehicle power supply circuit as a comparative example is a circuit that supplies an output voltage output from the battery 30 to the noise generating load 10 and the noise pulling load 20. In order to supply a voltage to the noise generating load 10 and the noise pulling load 20, a vehicle power supply circuit as a comparative example includes a first conductive path W1, a second conductive path W2, and a third conductive path W3. ing. Further, the vehicle power supply circuit as a comparative example accommodates the power supply circuit, and a part of the first conductive path W1, a part of the second conductive path W2, and a part of the third conductive path W3 are included. A junction box (J / B) 50 constituting a part of the power supply circuit and a fuse unit 60 directly connected to a terminal of the battery 30 are provided.

  The first conductive path W1 includes a power line W11 having one end connected to a fuel injection control device (INJ) 101 that is one of the noise generation loads 10, and an ignition device (IGN) that is one of the noise generation loads 10. A power line W12 having one end connected to 102, and a power line having one end connected to a fuel injection device (EFI) 103 that is one of the noise generating loads 10 and injects fuel together with ignition by an ignition plug of the ignition device 102 Branches to the bus bar of J / B50 at W13. On the other hand, the other end of the first conductive path W1 is connected to the other end of the second conductive path W2 and the other end of the third conductive path W3. A connection point between the other end of the first conductive path W1, the other end of the second conductive path W2, and the other end of the third conductive path W3 is referred to as P ′, and the power supply line W11 connected to the noise generating load 10 , W12, a section from one end of W13 to the connection point P ′ is defined as a first conductive path W1.

  One end of the second conductive path W2 is connected to an airbag electronic control unit (A / B ECU) 20 that is one of the noise pulling loads, and the other end is connected to the other end of the first conductive path W1 and the third. The other end of the conductive path W3 is connected at a connection point P ′. A section from one end of the power supply line connected to the noise pulling load to the connection point P ′ described above is defined as a second conductive path W2.

  One end of the third conductive path W3 is connected to the bus bar located on the fuse output terminal side of the fuse unit 60, and the other end is connected to the other end of the first conductive path W1 and the other end of the second conductive path W2. Connected. A section from the connection point P ′ to the power supply terminal of the battery 30 is defined as a third conductive path W3. Unlike the third conductive path W3 in the vehicle power supply circuit according to the first embodiment of the present invention, the third conductive path W3 in the vehicle power supply circuit as a comparative example is from J / B50 to the fuse unit 60. Includes power lines connecting the sections.

  The J / B 50 includes a fuse 402, a fuse 403, a relay 501, and a fuse 502, and these fuse and relay are fixed to the bus bar. The fuse 402 is provided on the power supply line W11 and the power supply line W12. The fuse 403 is provided on the power supply line W13. The relay 501 is provided on the third conductive path W <b> 3, and the switch is turned on by a current that is energized when the ignition device 102 is ignited. The fuse 502 is provided in the second conductive path W2. The connection point P ′ described above is located on the bus bar to which the fuse and the relay are fixed. The vehicle power supply circuit as a comparative example differs from the vehicle power supply circuit according to the first embodiment of the present invention in that R / B 40 shown in FIG. 1 is formed in J / B50.

  The fuse unit 60 includes a fuse provided with an input terminal and an output terminal with a fusible member interposed therebetween, and a bus bar to which the fuse is fixed. In the fuse unit 60, the input terminal of the fuse is connected to the power supply terminal of the battery 30 via the bus bar, and the output terminal of the fuse is connected to one end of the third conductive path W3 via the bus bar.

  In the vehicle power supply circuit as a comparative example, the noise generating load 10 and the noise pulling load 20 are the first conductive path W1, the second conductive path W2, the third conductive path W3, J / B 50, and the fuse unit 60. Electric power is supplied from the battery 30 via. The vehicle power supply circuit according to the first embodiment of the present invention and the vehicle power supply circuit as a comparative example are different in circuit configuration in the following points. That is, in the vehicle power supply circuit according to the first embodiment of the present invention, the battery 30 has a connection point P (see FIG. 1) between the other end of the first conductive path W1 and the other end of the second conductive path W2. On the other hand, the vehicle power supply circuit as a comparative example has a connection point P ′ between the other end of the first conductive path W1 and the other end of the second conductive path W2 (see FIG. 3). Is different from the battery 30 in the J / B 50.

  The reason why the connection point P ′ is located away from the battery 30 in the vehicle power supply circuit as a comparative example is that the conductive paths connected to the load are integrated into the J / B 50. The reason why the conductive paths are concentrated in J / B 50 in this manner is that the number of electronic devices mounted on the vehicle tends to increase, and it is possible to perform power management of these electronic devices with one unit. That is why. Moreover, J / B is arrange | positioned in the position which can make the length and weight of the electric wire used for a vehicle as small as possible while weight reduction of the wire harness routed in a vehicle is calculated | required. In such a situation, the J / B cannot always be arranged at a position close to the battery, and as a result, as shown in FIG. 3, the power supply line connecting the battery 30 and the J / B 50 is included. It was necessary to provide the third conductive path W3. The present inventor thinks that the fact that J / B is arranged at a position away from the battery is one of the factors that form a situation in which noise generated from the noise generating load is easily drawn into the noise pulling load. It came.

  Here, with reference to FIGS. 2 and 4, the operation of the vehicle power supply circuit according to the first embodiment of the present invention will be described in comparison with the vehicle power supply circuit as a comparative example. 4 shows only the configuration that affects the propagation of noise generated from the noise generating load 10 in the circuit diagram shown in FIG. 3 as in FIG. 2, that is, the noise generating load 10, the noise pulling load 20, and the battery. 30, the fuse unit 60 is taken out, and the equivalent circuit of the circuit structure which consists of those structures is described.

  As shown in FIGS. 2 and 4, the vehicle power supply circuit according to the first embodiment of the present invention and the vehicle power supply circuit as a comparative example include a closed circuit including a noise generating load 10 and a battery 30, noise A closed circuit including the retractable load 20 and the battery 30 is formed. 2 and 4, Z10 represents the impedance of the noise generating load 10, and Z20 represents the impedance of the noise pulling load 20. Also, RB is the internal resistance of the battery 30, RF is the resistance value included in the third conductive path W3 among the resistance values of the fuse unit 60, RW1 is the resistance value of the first conductive path W1, and RW2 is The resistance value of the second conductive path W2 is represented by RW3, and the resistance value of the third conductive path W3 other than RF is represented by RW3.

  First, how the noise generated from the noise generating load 10 propagates through the vehicle power supply circuit as a comparative example will be described with reference to FIG. Here, attention is paid to the noise NW1 that is generated from the noise generating load 10 and propagates through the first conductive path W1 toward the connection point P ′ of the second conductive path W2 and the third conductive path W3. When the noise NW1 propagating through the first conductive path W1 reaches the connection point P ′, part of the noise NW2 propagates toward the second conductive path W2, and the remaining part NW3 is transmitted through the third conductive path W3. Propagate towards. At this time, the ratio of the part NW2 of noise propagating toward the second conductive path W2 to the remaining part of the noise NW3 propagating toward the third conductive path W3 is determined from the connection point P ′ to the battery 30. Is the ratio of the line resistance when the noise pulling load 20 is viewed from the connection point P ′, that is, NW2: NW3 = (RB + RF + RW3) :( RW2 + Z20). From this, it can be seen that the noise NW2 propagating toward the second conductive path W2, that is, the noise drawn toward the noise pulling load 20, decreases as RW3 is smaller or RW2 is larger.

  Therefore, how the noise generated from the noise generating load 10 propagates through the vehicle power supply circuit according to the first embodiment of the present invention will be described with reference to FIG. Here, attention is also paid to the noise NW1 generated from the noise generating load 10 and propagating through the first conductive path W1 toward the connection point P between the second conductive path W2 and the third conductive path W3. When the noise NW1 propagating through the first conductive path W1 reaches the connection point P, a part of the noise NW2 propagates toward the second conductive path W2, and the remaining part NW3 enters the third conductive path W3. Propagate toward. At this time, the ratio of the noise part NW2 propagating toward the second conductive path W2 and the remaining noise part NW3 propagating toward the third conductive path W3 is determined from the connection point P to the battery 30. The ratio between the line resistance when viewed and the line resistance when the noise pulling load 20 is viewed from the connection point P, that is, NW2: NW3 = (RB + RF) :( RW2 + Z20). When compared with the vehicle power supply circuit as a comparative example, the vehicle power supply circuit according to the first embodiment of the present invention has the first conductive path W1 directly connected to the fuse unit 60 and the third conductive path W3. It can be seen that the noise NW2 drawn toward the noise pulling load 20 is reduced by the amount that the resistor RW3 is removed from the circuit configuration. Further, the second conductive path W2 is directly connected to the fuse unit 60, and the length of the second conductive path W2 is increased and the resistance RW2 of the second conductive path W2 is increased. It can also be seen that the noise NW2 is reduced.

  As described above, the vehicle power supply circuit according to the first embodiment of the present invention has a configuration in which one end of the first conductive path W1 is connected to the noise generating load 10 and the other end is connected to the fuse unit 60 of the battery 30. ing. As a result, the noise generation load 10 is more likely to receive noise than the conventional vehicle power supply circuit connected to the fuse unit 60 of the battery 30 via the power supply lines of the first conductive path W1 and the third conductive path W3. Noise that is drawn toward the load 20 can be reduced. As a result, a circuit configuration that suppresses noise from being drawn into the noise pulling load 20 can be realized.

  In the vehicle power supply circuit according to the first embodiment of the present invention, the section from the connection point P to the power supply terminal of the battery 30 in the bus bar of the fuse unit 60 is defined as the third conductive path W3. When the connection point P is close to the power supply terminal of the battery 30, for example, when the terminal located at the other end of the first conductive path is screwed to the power supply terminal of the battery 30, the third conductive path W3 can be regarded as missing. For this reason, in the vehicle power supply circuit according to the first embodiment of the present invention, the third conductive path W3 does not exist, that is, one end is connected to the noise generating load 10 that generates noise, and the other end is a battery. 30 includes a first conductive path W <b> 1 connected to 30, and a second conductive path W <b> 2 having one end connected to the noise pulling load 20 that draws noise and the other end connected to the battery 30.

  In FIG. 1, the dotted lines separating the noise generating load 10, the battery 30, the R / B 40 and the fuse unit 60 from the noise pulling load 20 and the J / B 50 are panels of the vehicle body on which the wire harness is routed. . The left side of the dotted line in FIG. 1 is, for example, an engine room, and the right side of the dotted line in FIG. 1 is, for example, a vehicle interior. A wire harness is routed on each panel.

  At this time, the wire harness routed in the engine room is located on the left in FIG. 1 rather than the dotted line of the sub-harness formed by the first conductive path W1 including the R / B and the second conductive path W2. You may make it comprise including the subharness formed by the part located in the direction.

  On the other hand, the first wire harness including the sub-harness formed by the first conductive path W1 including R / B, and the portion located on the left in FIG. 1 from the dotted line in the second conductive path W2. And a second wire harness including a sub-harness formed by the above-described method, and each wire harness may be routed in the engine room. In this case, the first wire harness connected to the noise generating load 10 also functions as a dedicated line for propagating noise from the noise generating load 10 toward the battery 30. This configuration is useful when the first conductive path W1 is connected to a plurality of noise generating loads 10 and noise is generated from each noise generating load 10.

(Second Embodiment)
FIG. 5 is a circuit diagram of a vehicle power supply circuit according to the second embodiment of the present invention. FIG. 6 is a diagram showing an equivalent circuit of the vehicle power supply circuit according to the second embodiment of the present invention. Hereinafter, with reference to FIG.5 and FIG.6, the circuit structure of the vehicle power supply circuit which concerns on 2nd Embodiment of this invention is demonstrated.

  The vehicle power supply circuit according to the second embodiment of the present invention is different from the vehicle power supply circuit according to the first embodiment of the present invention in that a power line is included in the third conductive path W3. Below, the description about the point demonstrated in 1st Embodiment is abbreviate | omitted.

  The third conductive path W3 has one end connected to the bus bar located on the output terminal side of the fuse, and the other end connected to the other end of the first conductive path W1 and the other end of the second conductive path W2. In the vehicle power supply circuit according to the first embodiment of the present invention, the other end of the first conductive path W1 is directly connected to the bus bar located on the input terminal side of the fuse, but the second embodiment of the present invention. In the vehicular power supply circuit, the other end of the first conductive path W1 is connected to a bus bar located on the output terminal side of the fuse via a third conductive path W3 having a power line.

  In designing the wire harness, it is also assumed that it is difficult to directly connect the other end of the first conductive path W1 to the bus bar located on the output terminal side of the fuse. Even in such a situation, the vehicle power supply circuit according to the second embodiment of the present invention realizes a circuit configuration that suppresses noise from being drawn into the noise pulling load 20.

  In the vehicle power supply circuit according to the second embodiment of the present invention, the third conductive path W3 has the following connection point P between the other end of the first conductive path W1 and the other end of the second conductive path W2. Designed to meet the requirements. That is, the line resistance when the noise pulling load 20 is viewed from the connection point P is larger than the line resistance when the battery 30 is viewed from the connection point P, that is, (RW2 + Z20)> (RB + RF + RW3). Designed as such.

  The manner in which the noise generated from the noise generating load 10 propagates through the vehicle power supply circuit according to the second embodiment of the present invention will be described with reference to FIG. Here, attention is paid to the noise NW1 generated from the noise generating load 10 and propagating through the first conductive path W1 toward the connection point P of the second conductive path W2 and the third conductive path W3. When the noise NW1 propagating through the first conductive path W1 reaches the connection point P, a part of the noise NW2 propagates toward the second conductive path W2, and the remaining part NW3 enters the third conductive path W3. Propagate toward. At this time, the ratio of the part NW2 of noise propagating toward the second conductive path W2 to the remaining part of the noise NW3 propagating toward the third conductive path W3 is determined by the battery 30 from the connection point P. The ratio between the line resistance when viewed and the line resistance when the noise pulling load 20 is viewed from the connection point P, that is, NW2: NW3 = (RB + RF + RW3) :( RW2 + Z20). At this time, if the third conductive path W3 is designed as described above, the noise NW2 propagating toward the second conductive path W2, that is, the noise drawn toward the noise pulling load 20 is Can be suppressed to less than half of the noise NW1 propagating through the conductive path W1. When the line resistance (RW2 + Z20) when the noise pulling load 20 is viewed from the connection point P is larger than the line resistance (RB + RF + RW3) when the battery 30 is viewed from the connection point P, the line resistance (RW + RF + RW3) is directed toward the second conductive path W2. Needless to say, the noise NW2 propagating in this manner is suppressed.

  When the connection point P is arranged at a position satisfying (RW2 + Z20)> (RB + RF + RW3), for example, the second conductive path W2 and the third conductive path W3 have the same resistance value per unit length. The second conductive path W2 may be longer than the third conductive path W3. With such a simple structure, the connection point P can be arranged at a position satisfying (RW2 + Z20)> (RB + RF + RW3).

  As described above, in the vehicle power supply circuit according to the second embodiment of the present invention, the noise generating load 10 is connected to the fuse unit 60 of the battery 30 via the first conductive path W1 and the third conductive path W3, and (RW2 + Z20 )> The connection point P is arranged at a position satisfying (RB + RF + RW3). Thereby, the noise NW2 propagating toward the second conductive path W2, that is, the noise drawn toward the noise pulling load 20 is suppressed to less than half of the noise NW1 propagating through the first conductive path W1. it can. As a result, a circuit configuration that suppresses noise from being drawn into the noise pulling load 20 can be realized.

10 Noise generating load 20 Noise pulling load 30 Battery 40 Relay box (R / B)
50 junction box (J / B)
60 fuse unit W1 first conductive path W2 second conductive path W3 third conductive path RB internal resistance of the battery RF fuse unit resistance RW1 first conductive path resistance RW2 second conductive path resistance RW3 third Resistance of conductive path of Z10 Impedance of noise generating load Z20 Impedance of noise pulling load

Claims (5)

A first conductive path having one end connected to a first load generating noise and the other end connected to a battery;
A second conductive path having one end connected to a second load that draws noise and the other end connected to the battery;
A vehicle power supply circuit comprising: A first conductive path having one end connected to a first load that generates noise;
A second conductive path connected to a second load having one end drawing noise;
A third conductive path having one end connected to the battery and the other end connected to the other end of the first conductive path and the other end of the second conductive path;
With
The line resistance when viewing the second load from the other end of the second conductive path is larger than the line resistance when viewing the battery from the other end of the third conductive path.
A power supply circuit for a vehicle. The second conductive path has a line length longer than that of the third conductive path.
The vehicular power supply circuit according to claim 2. The first conductive path is connected to a plurality of the first loads.
The vehicular power supply circuit according to any one of claims 1 to 3. The second conductive path constitutes a part of a power circuit in which a part thereof is accommodated in a power distributor.
The vehicle power supply circuit according to claim 1, wherein:

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