JPH09240392A - Safety protecting device for vehicular electric circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality and to shut off a current from a power source circuit by providing a comparing part for comparing the output of a first leaked current detecting part with the output of a second leaked current detecting part and inputting the result of comparison to a logic control part. SOLUTION: A logic control part 4 detects the existence of a leaked current based on the result of comparison made by a comparing part 6. A current control part 1 shuts off a circuit or performs a phase control/ON-OFF control. If an acceleration sensor 8 provided in a fuel valve detects an impact force of a specified value or higher, the logic control part 4 determines the occurrence of an accident such as clashing or the like, drives a fuel cut relay 9, stops fuel supplying, drives the current control part 1 so as to shut off the supplying of a current and thereby prevents the tiring to leaked gasoline caused to sparks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enables current interruption in response to various abnormalities of a load circuit by freely controlling the interruption characteristic of a power supply system according to the characteristics of the load circuit, Related to the safety protection device for the electric circuit, which is configured so that the power system can be shut off for safety even when an abnormality other than the above is detected. To prevent a vehicle fire and to prevent the ignition of gasoline by electric sparks by cutting off the electric current when a vehicle collision is detected. Regarding the device.

[0002]

2. Description of the Related Art Recently, many electronic devices are mounted on vehicles. The power supply to each electronic device and the wiring between the electronic devices are performed via a wire harness in which various cords are bundled. In order to prevent heat generation, smoke generation, and ignition due to an abnormal current such as a short circuit between wire harnesses, conventionally, a fuse that melts due to the heat due to an abnormal current in the circuit or a normal fuse is used to cope with a failure in the power supply system. A fusible link with a longer fusing time than was used. However, these conventional circuit protection elements such as fuses and fusible links (FLs) have the following problems, as schematically shown in FIG.

(1) In the case of a short-circuited short-circuit or an intermittently generated short-circuit (rare short-circuit), the time during which an abnormal current flows is too short, so that the temperature-sensitive circuit protection such as a fuse or fusible link is protected. The element cannot react and the current cannot be cut off due to heat generation and melting. (See Figure 4-1)

(2) When the core wire is broken due to the bending of the wire harness, a core wire short circuit occurs. But in this case,
Since a short circuit occurs between the same potential, a normal current will flow out, and a fuse or fusible link cannot handle this. (See Figure 4-2)

(3) Wires having different current capacities have different smoke emission characteristics. However, if a short circuit occurs between wires having different current capacities, fuses and fusible links are adjusted to the maximum current capacity during normal use. An abnormal situation occurs in which it is not blown because it is set. (See Figure 4-3)

(4) The size of the electric wire is excessive so that the electric wire does not emit smoke due to the rush current at the start of use of the load. Therefore, the quality is excessive in the steady energization region. (See Figure 4-4)

(5) Since the electric wire is body-grounded, the fuse and the fusible link cannot detect and deal with the leak current due to insulation failure or the like. (See Figure 4-5)

(6) When the core wire breaks due to the bending of the wire harness, heat is generated due to a half-contact or the like at the broken part. However, since the normal current is turned on / off, the fuse or fusible link cannot handle this. Therefore, an accident due to this may occur. (Fig. 4-6
reference)

[0009]

As described above, the conventional circuit protection device cannot detect an accurate abnormality corresponding to the characteristics and standards of various circuits and electric wires. According to the present invention, it is possible to appropriately deal with these abnormalities, and to detect an abnormality that could not be detected only from the current value of the power supply system, thereby cutting off the current from the power supply circuit. be able to.

[0010]

As means for solving the above problems, according to the present invention, a current is supplied from a power source to a load via a current control section and a load current detection section, and at that time, the load current detection section is supplied. The detection result of is input to the logic control unit, and the logic control unit provides the current control signal to the current control unit based on the determination based on the input. The leak current detecting unit is provided on the upstream side of the load, the second leak current detecting unit is provided on the downstream side of the load, and the outputs of the first leak current detecting unit and the second leak current detecting unit are compared to each other. The result is given to the logic controller.

Further, a storage unit for storing information about the load is provided so that the information in the storage unit is input to the logic control unit. Specifically, the smoke generation characteristic of the electric wire and the current flowing in the electric wire are stored in the storage unit. It is stored as a function of the flowing time. In this case, the smoke generation characteristic of the electric wire stored in the storage unit is stored as a function between the electric current flowing in the electric wire and the flowing time. As a result of experiments using various electric wires, as shown in FIG. Since it was found that the smoke emission limit of the electric wire is a linear function of the logarithm of the flowing current and the logarithm of the flowing time of the electric current, the current is cut off efficiently using this relationship.

Further, a plurality of load current detection units are connected to the load side of the current control unit, each load is connected to each load current detection unit, and information about each of the plurality of loads is stored in the storage unit. Remembered A sensor signal from an external sensor is also input to the logic control unit. Specifically, the sensor signal is a signal indicating the state of the switch and an acceleration signal.

Further, a fuel cut relay for shutting off fuel supply to the engine is provided, and a fuel cut signal can be given to this fuel cut relay from the logic control section. An abnormality display device for displaying an abnormality is also provided so that an abnormality display signal can be given to this abnormality display device from the logic control unit.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the configuration of a detection control circuit of a power supply system in a vehicle. A plurality of loads (3 ₁ ) are connected from the positive electrode of the battery (20) whose negative electrode is connected to the vehicle body chassis through the upstream leak current detection unit (5),
Current is supplied to (3 ₂ ), ... (3 _n ). From each of the loads (3 ₁ ), (3 ₂ ), ... (3 _n ) the negative electrode of the battery (20) is passed through the leak current detection section (5 ′) on the downstream side by an electric wire without passing through the vehicle body chassis. It is connected to the. Leak current detector (5),
The comparison result of the detected current value at (5 ′) in the comparison unit (6) is input to the logic control unit (4).

A current control unit (1) controlled by a logic control unit (4) is provided downstream of the current detection unit (5) on the upstream side, and the current control unit (1) controls each load (3 ₁ ) to (3). 3 ₂ ),
... Each load (3 ₁ ) until reaching (3 _n ),
Current detectors (2 ₁ ), (2 ₂ ), ... (2 _n ) by shunt resistors are provided corresponding to (3 ₁ ), ... (3 _n ). In addition, the information such as the on / off state of the switch is input to the logic control unit (4) as an input signal (7), and the impact due to a collision or the like is detected by the acceleration sensor (8) provided in the fuel valve. , To the logic control unit (4).

The smoke generation characteristic of the electric wire stored in the storage section (12) is stored as a function between the electric current I flowing through the electric wire and the flowing time t. The smoke generation characteristic of the electric wire is as shown in FIG. 3. If the current flowing through the electric wire is large, the time to smoke is short, and conversely, if the current is small, the time to smoke is long. Therefore, it is ideal that the current cutoff characteristic for protecting the electric wire is set at the end of the smoking area of the electric wire. However, no fuse or FL of the conventional device has the same characteristic as the electric wire smoke generating characteristic, and even if it exists, it is difficult to find it.
Therefore, there is no choice but to use the one having a characteristic similar to a part of the electric wire smoking characteristic. However, according to the present invention,
The smoke characteristic of the electric wire is stored in the storage unit (12), and the logic control unit (4) calculates the current I flowing through the electric wire each time and the duration t of the electric wire, and the calculation result is the smoke characteristic of the electric wire of FIG. Since it is determined whether or not it is within the smoke emitting area (hatched portion) of the current source, the current cutoff characteristic can be easily set at the last minute of the wire smoke emitting area.

Further, when storing the smoke generation characteristics of the electric wire in the storage unit (12) as a function between the current I flowing through the electric wire and the time t flowing through the electric wire, as a result of an experiment using various electric wires, as shown in FIG. As shown, the smoke emission limit of the wire is the flowing current I
It was found to be a linear function of the logarithm of and the logarithm of the time t at which the current flows. That is, in the case of the AVS0.3 electric wire, y = −2.2232x + 4.4441, where x = Log. I y = Log. t.

Similarly, for an AVS0.5 electric wire, y = -2.0443x + 4.3623, for an AVS0.85 electric wire, y = -2.0402x + 4.6771, and for an AVS1.25 electric wire, y =- It becomes 1.7856x + 4.434. That is, since a complicated quadratic function as shown in FIG. 3 can be represented by the linear function as described above, the calculation result can be obtained quickly. In this way, by utilizing the logarithmic relationship, it is possible to perform more efficient current interruption.

The logic control unit (4) detects the presence / absence of leak current based on the result of the comparison unit (6), and detects the values detected by the current detection units (2 ₁ ), (2 ₂ ), ... (2 _n ). , It is judged from the input signal (7) indicating the on / off state of the switch to the equipment and the reference current value of each load (3 ₁ ), (3 ₂ ), ... (3 _n ) whether it is an abnormal current or not. At the same time, it is determined whether or not to cut off based on the data of the storage unit (12) that stores the relationship between the allowable current value and the duration of the electric wire (11) to each load described above according to the smoke generation characteristics. It is given to the current control unit (1). The current control section (1) performs circuit interruption or phase control / on / off control based on the result. When the acceleration sensor (8) provided in the fuel valve detects an impact force of a predetermined value or more, the logic control unit (4) determines that an accident such as a collision has occurred, and the fuel cut relay (9). To stop the supply of fuel and drive the current control unit (1) to cut off the supply of current,
Prevent ignition from leaking gasoline due to sparks, etc.

Various protective operations carried out by the present invention having the above-mentioned structure are as follows. (A) Load circuit (3 _k )
In (1 ≦ k ≦ n), when a short circuit for a short time or a short circuit that occurs intermittently (rare short circuit) occurs,
The value detected by the current detector (2 _k ) is sent to the logic controller (4). The logic control unit (4) obtains an abnormal current value due to a short circuit, its duration, and a time integrated value, and
The state of the switch in the load circuit (3 _k ) obtained from the input signal (7), the reference current value for the load circuit (3 _k ) stored in the storage unit (12), the smoke characteristics of the used wire, etc. Based on the data (see FIG. 2), it is determined whether or not the current value is abnormal, and whether or not it is necessary to interrupt the current (see FIG. 3). If the electric current is in a marginal area where smoke does not occur even if it is an abnormal current value, only an anomaly is displayed and the current is not cut off, but if it reaches a dangerous area, the current is cut off.

(B) When the vehicle door or trunk is opened or closed, the wire harness fixed to the door or trunk is repeatedly bent. As a result, an abnormal situation may occur in which the core wire of the wire harness repeats a broken state and a contact state. In the present invention, the current detector (2
By comparing the detected values at ₁ ), (2 ₂ ), ... (2 _n ) with the switch status according to the input signal (7), it is possible to detect the occurrence of wire breakage, re-contact of broken wire, etc. Even if the current value is the reference value, it can be detected that an abnormality has occurred, the abnormal portion can be displayed, and a countermeasure can be taken before it becomes important.

(C) In the wire harness, electric wires having various thicknesses, that is, various electric current capacities and smoke emission characteristics are bundled. In the case where short circuit occurs between the wires of different properties, the current detection unit (2 _1), (2 _2), ...
Since it is possible to determine anomaly from each current value of (2 _n ), it is possible to detect anomaly even when there is a short circuit between wires with different characteristics, and it is appropriate according to the smoke emission characteristics of that wire. The current can be cut off at any time.
Further, even when there is a large inrush current, it is not necessary to use an electric wire having an excessive current capacity in consideration of the inrush current, which is effective in reducing the weight of the harness wire.

(D) If insulation failure (10) between the wiring of the load circuit and the chassis of the vehicle body occurs, a leak current is generated. As a result, a part of the current flows through the chassis of the vehicle body, so that a difference occurs in the outputs of the leak current detection units (5) and (5 ′). The comparison unit (6) sends the result of comparing the outputs to the logic control unit (4). The logic control unit (4) displays that the output is abnormal when the difference between the outputs is equal to or more than a predetermined value,
When the dangerous area is reached, the current is cut off by the current controller (1).

(E) When the logic control unit (4) detects an impact force of a predetermined value or more by the acceleration sensor (8) provided in the fuel valve, there is a risk of gasoline leakage, so the logic control unit ( 4) commands the fuel cut relay (9) to stop the fuel supply, and at the same time controls the current control unit (1).
Command to shut off the current. This can prevent accidents due to gasoline leaks.

[0025]

As described above, according to the present invention, when a rare short circuit occurs, the value detected by the current detection section is sent to the logic control section, and the state of the switch and the used electric wire stored in the storage section are stored. From the data such as smoke generation characteristics, it is judged whether it is an abnormal current value or whether it is necessary to cut off the current, and the wire breakage of the wire harness occurs due to repeated opening and closing of the vehicle door and trunk. By comparing the detected value of the current detection unit with the state of the switch based on the input signal, it is possible to detect the occurrence of a disconnection state, re-contact of the disconnection point, and the like.

When a short circuit occurs between wires having different characteristics, it is possible to make an abnormality determination from the respective current values of the current detecting section, so that an abnormality is detected even for a short circuit between wires having different characteristics. can do. The current can be cut off at an appropriate time according to the smoke generation characteristic of the electric wire.

Further, even if there is a large inrush current, it is not necessary to use an electric wire having an excessive current capacity in consideration of the inrush current, which is effective in reducing the weight of the harness wire. If insulation failure occurs between the wiring of the load circuit and the chassis of the vehicle body, a leak current is generated. As a result, a part of the current flows through the chassis of the vehicle body. There will be a difference in output, so
When this difference is captured and the output difference is equal to or greater than a predetermined value, it is displayed as abnormal, and when the dangerous area is reached, the current can be cut off by the current controller.

Further, when the acceleration sensor detects an impact force of a predetermined value or more, the fuel cut relay is instructed to stop the fuel supply, so that even if a gasoline leak occurs, an electric spark may ignite. Accidents can be prevented.

As described above, according to the present invention, the logic control unit compares the leakage current, the current to each load, and the detection output of the acceleration sensor with the input signal and the stored characteristics of each load or wire. By doing so, the abnormality is displayed and the current is cut off.At that time, it is judged whether or not there is an abnormality by comparing each measured value with the expected reference value. The judgment is made by considering each allowable range, and the safety is extremely higher than that of the conventional fuse or fusible link that cuts off the current based on a uniform standard.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a safety protection device for an electric circuit for a vehicle which is an embodiment of the present invention.

FIG. 2 is a smoke generation characteristic according to a current I flowing through various electric wires and a time t until smoke generation.

FIG. 3 shows an example of setting a current interruption characteristic based on a smoke generation characteristic of an electric wire.

FIG. 4 is an example of various problems.

[Explanation of symbols]

1: current control unit 2 ₁ ... 2 _n : current detection unit 3 ₁ ... 3 _n : load 4: logic control unit 5, 5 ': leak current detection unit 6: comparison unit 7: input signal 8: acceleration Sensor 9: Fuel cut relay 10: Insulation failure 11: Electric wire 12: Storage section 20: Battery

Claims (8)

[Claims] 1. A current is supplied from a power supply to a load via a current control unit and a load current detection unit, and at that time, a detection result of the load current detection unit is input to a logic control unit, and the logic control unit inputs the input. In a safety protection device for a vehicle electric circuit configured to give a current control signal to a current control unit based on a determination based on, a first leak current detection unit provided on the upstream side of the load and a downstream side of the load on the downstream side of the load. A second leak current detector provided, and a comparator that compares the outputs of the first leak current detector and the second leak current detector, and the result of the comparator is the logic controller. A safety protection device for an electric circuit for a vehicle, which is characterized in that it is input to the. 2. The safety protection device for an electric circuit for a vehicle according to claim 1, further comprising a storage unit for storing information about the load, and inputting the information in the storage unit to the logic control unit. Safety protection device for electric circuits for vehicles. 3. The safety protection device for an electric circuit for a vehicle according to claim 2, wherein the storage unit stores the smoke generation characteristic of the electric wire as a function between a current flowing through the electric wire and a flowing time. Safety protection device for vehicle electric circuits. 4. The safety protection device for a vehicle electric circuit according to claim 3, wherein a plurality of load current detection units are connected to a load side of the current control unit, and each load current detection unit has a respective load. Is connected, and information on each of a plurality of loads is stored in the storage unit. 5. The vehicle electrical circuit safety protection device according to claim 1, wherein a sensor signal from an external sensor is input to the logic control unit. Electrical circuit safety protection device. 6. The safety protection device for a vehicle electric circuit according to claim 5, wherein the sensor signal is a signal indicating a state of a switch and an acceleration signal. 7. The safety protection device for an electric circuit for a vehicle according to claim 1, further comprising a fuel cut relay for cutting off fuel supply to an engine, the fuel cut relay including the logic control unit. A safety protection device for an electric circuit for a vehicle, which is provided with a fuel cut signal from the vehicle. 8. The safety protection device for an electric circuit for a vehicle according to claim 1, further comprising an abnormality display device for displaying an abnormality, and the abnormality display device displays an abnormality on the abnormality display device. A safety protection device for an electric circuit for a vehicle, which is provided with a signal.