CUTOFF DEVICE FOR VEHICLE AND CUTOFF METHOD

An in-vehicle cutoff device includes a first input terminal, a first output terminal, a first conductor wire, a second input terminal, a second output terminal, a second conductor wire, a first current detector capable of detecting a current flowing through the first conductor wire or the second conductor wire, a second current detector capable of detecting a current flowing through the first conductor wire or the second conductor wire, a pyrotechnic circuit breaker capable of irreversibly disconnecting the first conductor wire, and controller capable of controlling a cutoff operation of the pyrotechnic circuit breaker in response to the detected currents. The controller causes the cutoff operation of the pyrotechnic circuit breaker to perform the cutoff operation when both of a first current value generated based on a first detection signal and a second current value generated based on the second detection signal exceed an overcurrent threshold.

TECHNICAL FIELD

The present invention relates to an in-vehicle cutoff device and a cutoff method used in various vehicles.

BACKGROUND ART

A conventional cutoff device will be explained below. Conventional cutoff devices includes a pyrotechnic switch connected between a battery and a load, and a control circuit for controlling the pyrotechnic switch. The control circuit detects the current being supply from the battery to the load, and the condition of the vehicle, and drives to ignite the pyrotechnic switch depending on the current and the condition of the vehicle.

As prior art document information related to the invention according to this application, Patent Document 1 is known, for example.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

In such a conventional cutoff device, however, when an overcurrent condition needing a cutoff operation is detected in the current flowing from the battery to the load, and it is determined that the pyrotechnic switch needs to be driven and ignited, for example, it has been not possible to determine whether such an operation of making a detection related to an overcurrent is appropriate or erroneous. For this reason, the control circuit sometimes ended up detecting and determining that an overcurrent has occurred and drives to ignite the pyrotechnic switch, although actually no overcurrent has occurred; or detecting and determining that no overcurrent has occurred and fails to drive to ignite the pyrotechnic switch, although an overcurrent has actually occurred. As a result, reliability of the operation of the cutoff device might deteriorate, disadvantageously.

Therefore, an object of the present invention is to improve the reliability of cutoff-related operations.

In order to achieve this object, the present invention is characterized by an in-vehicle cutoff device including: a first input terminal to which direct-current (DC) power of a first polarity is supplied; a first output terminal; a first conductor wire connecting the first input terminal and the first output terminal; a second input terminal to which DC power having a second polarity opposite to the first polarity is supplied; a second output terminal; a second conductor wire connecting the second input terminal and the second output terminal; a first current detector configured to detect a current flowing through the first conductor wire or the second conductor wire; a second current detector configured to detect a current flowing through the first conductor wire or the second conductor wire; a pyrotechnic circuit breaker configured to irreversibly disconnect the first conductor wire; and a controller configured to receive a first detection signal transmitted from the first current detector and a second detection signal transmitted from the second current detector, the first detection signal corresponding to the current detected by the first current detector, the second detection signal corresponding to the current detected by the second current detector, the cutoff controller configured to control a cutoff operation of the pyrotechnic circuit breaker, in which the controller causes the cutoff operation of the pyrotechnic circuit breaker to perform the cutoff operation when both of a first current value generated based on the first detection signal and a second current value generated based on the second detection signal exceed an overcurrent threshold.

According to the present invention, it is possible to activate the cutoff operation based on an overcurrent detected using a plurality of current detectors, so that the reliability of the operation of the in-vehicle cutoff device can be improved.

DESCRIPTION OF EMBODIMENT

An exemplary embodiment of the present invention will now be explained with reference to some drawings.

EXEMPLARY EMBODIMENT

FIG.1is a first circuit block diagram illustrating a configuration of in-vehicle cutoff device1according to the exemplary embodiment of the present invention. In-vehicle cutoff device1includes first input terminal2, first output terminal3, first conductor wire4, second input terminal5, second output terminal6, second conductor wire7, first current detector8, second current detector9, pyrotechnic circuit breaker10, and controller11.

DC power at a first polarity is supplied to first input terminal2. First conductor wire4connects first input terminal2and first output end3. DC power having a second polarity opposite to the first polarity is supplied to second input terminal5. Second conductor wire7connects second input terminal5and second output terminal6.

First current detector8can detect a current flowing through first conductor wire4or second conductor wire7. Second current detector9can detect a current flowing through first conductor wire4or second conductor wire7. Pyrotechnic circuit breaker10is disposed in a manner enabled to irreversibly disconnect first conductor wire4. Controller11can receive first detection signal S1and second detection signal S2. First detection signal S1is transmitted from first current detector8correspondingly to a current detected thereby, and second detection signal S2is transmitted from second current detector9correspondingly to a current detected thereby. Controller11can also control a cutoff operation of pyrotechnic circuit breaker10.

Controller11causes pyrotechnic circuit breaker10to perform the cutoff operation when first current value I1generated based on first detection signal S1and second current value I2generated based on second detection signal S2both exceed overcurrent threshold value Ith.

With the above configuration and operation, an overcurrent can be detected using the plurality of current detectors that are first current detector8and second current detector9, and a cutoff operation can be activated based on the plurality of detection results. As a result, the reliability of the operation of in-vehicle cutoff device1can be improved.

In-vehicle cutoff device1will now be described in detail. As mentioned above, in-vehicle cutoff device1includes first input terminal2, first output terminal3, first conductor wire4, second input terminal5, second output terminal6, second conductor wire7, first current detector8, second current detector9, pyrotechnic circuit breaker10, and controller11.

In-vehicle cutoff device1is disposed on vehicle body13of vehicle12. Vehicle power supply14and vehicle load15are disposed on vehicle body13. Vehicle power supply14is a power supply mainly used for propelling and driving vehicle12, and a lithium battery is used as an electricity storage element, as an example. Vehicle load15is a load mainly for propelling and driving vehicle12, and vehicle load15mainly corresponds to a part or all of an inverter device (not illustrated) that converts DC power supplied from vehicle power supply14into three-phase AC power, and a motor (not illustrated) driven by three-phase AC power supplied by the inverter device (not illustrated).

In-vehicle cutoff device1is connected to vehicle power supply14and vehicle load15. First electrode14A of vehicle power supply14is connected to first input terminal2. Second electrode14B of vehicle power supply14is connected to second input terminal5. First electrode14A is a positive electrode, and second electrode14B is a negative electrode. First electrode15A of vehicle load15is connected to first output terminal3. Second electrode15B of vehicle load15is connected to second output terminal6.

First conductor wire4connects first input terminal2and first output terminal3. Second conductor wire7connects second input terminal5and second output terminal6. First current detector8is provided to detect a current flowing through first conductor wire4. Second current detector9is provided to detect the current flowing through first conductor wire4. Pyrotechnic circuit breaker10is disposed in a manner enabled to irreversibly disconnect first conductor wire4that is on a positive potential side.

Controller11can receive first detection signal S1and second detection signal S2. First detection signal S1is transmitted from first current detector8correspondingly to a current flowing through first conductor wire4and detected thereby, and second detection signal S2is transmitted from second current detector9correspondingly to the current detected thereby. Controller11can also control a cutoff operation of pyrotechnic circuit breaker10.

Hereinafter, the step of causing first current detector8to generate first detection signal S1will be referred to as a first current detection step. Hereinafter, the step of causing second current detector9to generated second detection signal S2will be referred to as a second current detection step.

Controller11may be a functional element including all of a calculation function for determining first current I1based on first detection signal S1and determining second current I2based on second detection signal S2, a storage function for storing therein the calculation results, a function for issuing a command to pyrotechnic circuit breaker10, and the like. Furthermore, these functions of controller11may be provided as a single element or may be provided as a plurality of distributed elements.

Hereinafter, the step of determining first current I1based on first detection signal S1and the step of determining second current I2based on second detection signal S2will be referred to as a calculation step.

First detection signal S1transmitted from first current detector8and second detection signal S2transmitted from second current detector9may be analog data signals output from a shunt resistor or a Hall element, or may be digital data signals generated processing and digitally converting the analog signals output from the shunt resistor or the Hall element.

With a detection method using shunt resistors as first current detector8and second current detector9, currents can be detected highly accurately. A shunt resistor is preferably used to detect a current in linear first conductor wire4or second conductor wire7where parasitic inductance is rarely generated, or to detect a current in shorter one of first conductor wire4and second conductor wire7, in the comparison between first conductor wire4and second conductor wire7.

In addition, with a detection method using Hall elements as first current detector8and second current detector9, current can be detected highly responsively. Therefore, a shunt resistor or a Hall element may be used as first current detector8or second current detector9selectively, depending on the characteristics required in the current detections.

Furthermore, first relay16is provided on first conductor wire4on the positive potential side. First relay16then supplies the power or disconnect the power from vehicle power supply14to vehicle load15, in response to a command from controller11. In the same manner, second relay17is provided on second conductor wire7that is on the negative potential side. Second relay17then supplies the power or disconnects the power from vehicle power supply14to vehicle load15, in response to a command from controller11.

Controller11causes pyrotechnic circuit breaker10to perform the cutoff operation when first current value I1generated based on first detection signal S1and second current value I2generated based on second detection signal S2both exceed overcurrent threshold value Ith. Hereinafter, the step of causing pyrotechnic circuit breaker10to execute the cutoff operation when both first current value I1and second current value I2exceed overcurrent threshold Ith will be referred to as a cutoff step.

With the above configuration and operation, an overcurrent can be detected using the plurality of current detectors that are first current detector8and second current detector9, and a cutoff operation can be activated based on the plurality of detection results. Furthermore, when both first current detector8and second current detector9detect an overcurrent, controller11determines that the overcurrent has occurred. With this, it is possible to increase the probability at which the detected current flowing through first conductor wire4is an overcurrent, so that controller11can correctly determine that an overcurrent has occurred. As a result, the reliability of the operation of in-vehicle cutoff device1can be improved.

As illustrated inFIG.2that is a second circuit block diagram illustrating a configuration of in-vehicle cutoff device1according to the exemplary embodiment of the present invention, first current detector8is provided to detect the current flowing through second conductor wire7. Second current detector9is provided to detect the current flowing through second conductor wire7.

In particular, in the example herein, both first current detector8and second current detector9detect the current flowing through second conductor wire7that is a conductor wire having a negative potential, and then controller11makes the determination based on first current value I1and second current value I2. In this manner, first current detector8and second current detector9are disposed on second conductor wire7, and pyrotechnic circuit breaker10is disposed on first conductor wire4, in a separate manner. Therefore, it is possible to keep the lengths of the conductors used in first conductor wire4and second conductor wire7short.

As a result, it is possible to suppress parasitic inductance and impedance generated on first conductor wire4and second conductor wire7, and the accuracy of the current detection at the time of a sudden change the current can be improved. In this manner, the reliabilities of the operations of in-vehicle cutoff device1and pyrotechnic circuit breaker10are improved. In addition, because the impedance balance between first conductor wire4and second conductor wire7can be better ensured, it is possible to suppress common mode noise caused by ripples or noise in the current flowing through first conductor wire4and second conductor wire7. As a result, the accuracies of the current detection of first current detector8and second current detector9are improved, and therefore, reliabilities of the operation of in-vehicle cutoff device1and pyrotechnic circuit breaker10are improved.

As illustrated inFIG.3that is a third circuit block diagram illustrating a configuration of in-vehicle cutoff device1according to the exemplary embodiment of the present invention, first current detector8is provided to detect the current flowing through first conductor wire4. Second current detector9is provided to detect the current flowing through second conductor wire7.

In particular, in the example herein, first current detector8detects a current flowing through first conductor wire4that is a conductor wire with a positive potential, and second current detector9detects a current flowing through second conductor wire7that is a conductor wire with a negative potential, and then controller11makes the determination based on first current value I1and second current value I2. As a result, the effect of the common mode noise from vehicle load15is suppressed, so that the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10can be improved.

In this example, first current detector8detects a current flowing through first conductor wire4that is a positive potential conductor wire, and second current detector9detects a current flowing through second conductor wire7that is a negative potential conductor wire. Therefore, first detection signal S1and second detection signal S2cancel out the in-phase noise caused by the noise generated in vehicle load15such as the inverter circuit. In this manner, the noise in the detected first current value I1and second current value I2can be reduced. As a result, first detection signal S1output from first current detector8and second detection signal S2output from second current detector9become highly reliable signals, therefore, the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10are improved.

Furthermore, first current detector8and second current detector9execute the current detector based on the potential difference of the shunt resistor. The effect of the parasitic inductance is then reduced by setting different resistance values to first current detector8and second current detector9, respectively, and by calculating a difference in the values detected by first current detector8and second current detector9. As a result, it becomes possible to detect an overcurrent that goes through a particularly large change per unit at a higher accuracy, and therefore, the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10is improved. In the above description, controller11determines that an overcurrent has occurred when both first current detector8and second current detector9detects the overcurrent. However, it is also possible for controller11to determine that the overcurrent has occurred when at least one of first current detector8and second current detector9detects the overcurrent. Therefore, when the current to be detected flowing through first conductor wire4is an overcurrent, controller11can determine that the overcurrent has occurred at the point in time at which more responsive one of first current detector8and second current detector9has detected the overcurrent. As a result, the reliability of the operation of in-vehicle cutoff device1can be improved.

At this time, first current detector8can detect the current flowing through first conductor wire4or second conductor wire7. Second current detector9can detect a current flowing through first conductor wire4or second conductor wire7. In particular, as illustrated inFIG.1, both first current detector8and second current detector9detect a current flowing through first conductor wire4that is a conductor wire having a positive potential, and then controller11makes the determination based on first current value I1and second current value I2.

As a result, even when any one of first current detector8and second current detector9fails, the overcurrent can be detected by operative one of first current detector8and second current detector9. Therefore, the safety of the operation in case of a failure of any one of first current detector8and second current detector9can be improved. Furthermore, a highly reliable detection function can be implemented, without causing a deteriorating in the failure rate of the current detection function of entire in-vehicle cutoff device1.

As one example of a failure of the current detection function, the current detection function may fall into an overcurrent state mode failure, in which first current detector8or second current detector9erroneously recognizes that an overcurrent exceeding the overcurrent threshold value Ith is detected, and outputs such first detection signal S1or second detection signal S2. As a result, first current detector8or second current detector9fails to detect the overcurrent correctly and malfunctions. However, by using the configuration and operation described above, operative one of first current detector8and second current detector9can maintain the current detection function.

As a result, the reliability of the operation of in-vehicle cutoff device1, particularly that of pyrotechnic circuit breaker10, is improved. Even when either first current detector8or second current detector9outputs a false detection signal as first detection signal S1or second detection signal S2, as a result of being affected by the noise generated inside and outside in-vehicle cutoff device1, the effect of the noise can be suppressed, and false ignition of pyrotechnic circuit breaker10can be prevented, unless the noise gets into both of first current detector8and second current detector9simultaneously. In other words, by using different current detection schemes such as a shunt resistor and a Hall element, first current detector8and second current detector9can be ensured with different characteristics with respect to noise, so that the effect of noise in in-vehicle cutoff device1can be alleviated.

Furthermore, it is also possible, as illustrated inFIG.2, for both first current detector8and second current detector9to detect the current flowing through second conductor wire7that is the conductor wire having a negative potential, and for controller11to make the determination based on first current value I1and second current value I2.

Furthermore, it is also possible, as illustrated inFIG.3, for first current detector8to detect the current flowing through first conductor wire4that is a conductor wire with a positive potential; for second current detector9to detect the current flowing through second conductor wire7that is a conductor wire with a negative potential; and for controller11to make the determination based on first current value I1and second current value I2.

In the above description, pyrotechnic circuit breaker10is disposed in a manner enabled to irreversibly disconnect first conductor wire4that is on the positive potential side. At this time, as illustrated in inFIG.4that is a fourth circuit block diagram illustrating a configuration of in-vehicle cutoff device1according to the exemplary embodiment of the present invention, pyrotechnic circuit breaker10may be disposed to irreversibly disconnect second conductor wire7that is on the negative potential side.

In this example, it is possible to detect an overcurrent using a plurality of current detectors including first current detector8and second current detector9, and to activate the cutoff operation based on a plurality of detection results. Furthermore, when both first current detector8and second current detector9detect an overcurrent, controller11determines that the overcurrent has occurred. With this, it is possible to increase the probability at which the detected current flowing through first conductor wire4is an overcurrent, so that controller11can correctly determine that an overcurrent has occurred. As a result, the reliability of the operation of in-vehicle cutoff device1can be improved.

In particular, both first current detector8and second current detector9detect the current flowing through first conductor wire4that is a positive potential conductor wire, and then controller11performs the determination based on first current value I1and second current value I2. As a result, first current detector8, second current detector9, and pyrotechnic circuit breaker10are arranged dispersedly on second conductor wire7and first conductor wire4. In this manner, conductor lengths of first conductor wire4and second conductor wire7can be kept short.

As a result, it is possible to suppress parasitic inductance and impedance generated on first conductor wire4and second conductor wire7, and the accuracy of the current detection at the time of a sudden change the current can be improved. In this manner, the reliabilities of the operations of in-vehicle cutoff device1and pyrotechnic circuit breaker10are improved. In addition, because the impedance balance between first conductor wire4and second conductor wire7can be better ensured, it is possible to suppress common mode noise caused by ripples or noise in the current flowing through first conductor wire4and second conductor wire7. As a result, the accuracies of the current detection of first current detector8and second current detector9are improved, and therefore, reliabilities of the operation of in-vehicle cutoff device1and pyrotechnic circuit breaker10are improved.

As illustrated inFIG.5that is a fifth circuit block diagram illustrating a configuration of in-vehicle cutoff device1according to the exemplary embodiment of the present invention, pyrotechnic circuit breaker10is also disposed to irreversibly disconnect second conductor wire7that is on the negative potential side; first current detector8detects the current flowing through first conductor wire4that is the positive potential side conductor wire; and second current detector9detects the current flowing through second conductor wire7that is the negative potential side conductor wire. Controller11then makes the determination based on first current value I1and second current value I2. As a result, the effect of the common mode noise from vehicle load15is suppressed, so that the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10can be improved.

In this example, first current detector8detects a current flowing through first conductor wire4that is a positive potential conductor wire, and second current detector9detects a current flowing through second conductor wire7that is a negative potential conductor wire. For this reason, in-phase noise generated in vehicle load15such as an inverter circuit is canceled out. Therefore, it is possible to suppress in-phase noise. As a result, first detection signal S1output from first current detector8and second detection signal S2output from second current detector9become highly reliable signals, therefore, the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10are improved.

Furthermore, first current detector8and second current detector9execute the current detector based on the potential difference of the shunt resistor. The effect of the parasitic inductance is then reduced by setting different resistance values to first current detector8and second current detector9, respectively, and by calculating a difference in the values detected by first current detector8and second current detector9. As a result, it becomes possible to detect an overcurrent that goes through a particularly large change per unit at a higher accuracy, and therefore, the reliabilities of the operation of in-vehicle cutoff device1and the operation of pyrotechnic circuit breaker10is improved.

INDUSTRIAL APPLICABILITY

The in-vehicle cutoff device according to the present invention has an effect of improving the reliability of cutoff-related operations, and is useful in various vehicles.

REFERENCE MARKS IN THE DRAWINGS