WO2007080304A1

WO2007080304A1 - Battery circuit breaker comprising current-measuring means

Info

Publication number: WO2007080304A1
Application number: PCT/FR2007/000025
Authority: WO
Inventors: Per-Anders Forsberg
Original assignee: Diamecans
Priority date: 2006-01-10
Filing date: 2007-01-09
Publication date: 2007-07-19
Also published as: FR2896085A1; EP1971995A1; FR2896085B1

Abstract

The present invention relates to a circuit breaker (1) comprising an input electrical terminal (100), which is intended to be connected to a storage battery and comprises a body connected at one of its ends to a fixed contact element, an output electrical terminal (200), contact means (3) designed to open or close the electrical contact between the input and output electrical terminals, and means for measuring the current passing through the input electrical terminal. According to the invention, the current measuring means comprise, on the one hand, means for measuring the voltage between two measurement points on the input electrical terminal and means for calculating the intensity of the current from said voltage and, on the other hand, an electrical circuit comprising, in series, a switch and a resistor of known value, said electrical circuit being connected on one side to a point of known potential and on the other side to one of said measurement points, which is placed near the contactor element and the potential of which is measured by the voltage measurement means.

Description

BATTERY CIRCUIT BREAKER COMPRISING MEANS FOR MEASURING THE

CURRENT

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention generally relates to the measurement of the intensity of a current delivered by an accumulator battery in a circuit breaker. It relates more particularly to a circuit breaker comprising an electrical input terminal which is intended to be connected to a storage battery and which comprises a body connected at one of its ends to a fixed contact element, an electrical output terminal, contact means adapted to close or open the electrical contact between the two electrical input and output terminals cooperating with said fixed contactor element, and means for measuring the current flowing into the input electrical terminal.

It also relates to a method for measuring an electric current delivered by an accumulator battery and passing through an electrical input terminal of such a circuit breaker and a method for determining the state of the contact means of such a circuit breaker.

TECHNOLOGICAL BACKGROUND

At present, document US 2005/0057865 is already known from a printed circuit for controlling the energy of a motor vehicle, which is connected to the terminals of the storage battery of this vehicle in order to make measurements on this accumulator battery. .

The main disadvantage of such a printed circuit is that it is independent of any circuit breaker, so that it generates, with respect to the circuit breaker of the vehicle, an additional bulk and requires clean conditioning means. In addition, because of its eccentric position relative to the circuit breaker, the measurements made by this printed circuit are not easily exploitable by the circuit breaker, unless used between the printed circuit and the circuit breaker means of bulky, expensive communication with limited reliability.

A circuit breaker of the aforementioned type is also known in which the measuring means comprise a hall effect sensor mounted on the external face of the electrical input terminal. This sensor is conventionally constituted by a semiconductor wafer fed by a supply current. This plate is sensitive to the presence of a magnetic field perpendicular to it, such a field generating a measurable potential difference between each of its faces. The main disadvantage of such measuring means is that they have a low accuracy and are sensitive to surrounding magnetic fields produced by sources other than the electrical input terminal of the circuit breaker.

OBJECT OF THE INVENTION

In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes means for more accurate measurement of the intensity of the current passing through the electrical input terminal of the circuit breaker.

More particularly, it is proposed according to the invention a circuit breaker as defined in the introduction, wherein the current measuring means comprise, on the one hand, means for measuring the voltage between two measuring points of the electrical input terminal and means for calculating the intensity of the current from said voltage, and, on the other hand, an electrical circuit comprising in series a switch and a resistance of known value, said electrical circuit being connected to one side at a known potential point and the other at one of said measuring points which is disposed near the contactor element and whose potential is measured by the voltage measuring means.

Thus, thanks to the invention, since the resistances are generally insensitive to the surrounding magnetic fields, it is possible to accurately measure the electrical potential at two measurement points of the electrical input terminal. These two measured potentials then make it possible, by knowing the value of the internal resistance of the electrical input terminal between the two measuring points, to calculate the value of the intensity of the current delivered by the accumulator battery.

This measurement can also be performed in the open or closed position of the switch so that it is possible to refine this value of the intensity of the current delivered by the storage battery in the circuit breaker. In fact, taking into account the difference between the potentials measured in the open or closed position of the switch makes it possible to calibrate the means for measuring the current. According to a first advantageous characteristic of the circuit breaker according to the invention, the electrical input terminal comprises a hollow body.

Thus, the internal resistance of the material constituting the electrical input terminal between the two measurement points is greater. However, for the same intensity, when the resistance increases, the voltage to be measured also increases. The accuracy of the calculation of the intensity of the current passing through the electrical input terminal is thus increased.

Other advantageous and non-limiting characteristics of the circuit breaker according to the invention are the following: the measurement means comprise two wires connected on one side to one of the measuring points, and on the other side to an input of a subtractive operational amplifier;

the switch is an electrical transistor;

the known potential point is connected to the electrical ground of the circuit breaker;

the value of said resistor is at least ten times greater than the value of the internal resistance of the input terminal between the two measurement points;

- The circuit breaker comprises means for measuring an electrical potential at a point of the electrical output terminal; the circuit breaker comprises means for comparing the electrical potentials measured on the electrical input and output terminals; and

the electrical output terminal comprises a hollow body.

The invention also relates to a method for measuring an electric current delivered by an accumulator battery and passing through an input terminal of such a circuit breaker, which comprises the steps of:

- Note a first potential difference measured by the voltage measuring means and a first potential of the measuring point on which is connected the electrical circuit;

calculating, as a function of the value of the internal resistance of the electrical input terminal and of the first measured potential difference, the approximate value of the intensity of the current flowing through the electrical input terminal;

- close the switch; - Note a second potential difference measured by the voltage measuring means and a second potential of the measuring point on which the electrical circuit is connected;

calculating, as a function of the variation between the first and second measured potential differences, the variation between the first and second potentials at the measurement point, and the approximate value of the intensity of the calculated current, a refined value of the intensity of the current passing through the electrical input terminal; and

- open the switch. According to a first advantageous characteristic of the method according to the invention, the temperature of the input electrical terminal is measured and the value of the difference between the approximate value and the refined value of the intensity of the current passing through the terminal is memorized. electrical input to which said temperature is associated. Advantageously, an internal resistance of a power supply cable connected between the storage battery and the electrical input terminal is determined and the internal resistance and the variation between the first and second potential differences are calculated as a function of said internal resistance. measured, the value of the internal resistance of the storage battery. Thus, it is possible to accurately identify this characteristic of the battery which can provide information relating for example to its remaining life or its charging cycles. This information can then possibly be processed by the circuit breaker so that it can more effectively manage the charging and discharging cycles of the storage battery.

Advantageously, prior to the implementation of said steps, the contact means is opened.

Thus, the intensity of the current flowing through the input terminal is identical to that of the current flowing through the switch and the resistance of known value. Measuring the intensity of the current delivered by the accumulator battery is therefore easier since the entire current flowing through the electrical circuit comprising in series the switch and the resistance of known value passes first through the internal resistance of the battery. electrical input terminal (between the two measuring points). The invention also relates to a method for determining the state of contact means of such a circuit breaker in which the values of electrical potentials measured by the measuring means are recorded on the electrical input and output terminals, and deduce the open or closed position of the contact means.

Advantageously, values of the electrical potentials measured by the measuring means on the input and output electrical terminals are deduced, the state of wear of the contact means.

Thus, does the method take advantage of the fact that, knowing the value of the potential difference between two points each placed on one of the electrical input and output terminals, it is possible to determine first of all whether the means of contact are open or closed and, if closed, the electrical losses in the circuit breaker relating to the state of wear of the latter, and in particular that of its contact means. DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings given as non-limiting examples, will make it clear what the invention is and how it can be achieved.

In the accompanying drawings: FIG. 1 is a perspective view of the inside of a casing of a circuit breaker according to the invention;

- Figure 2 is a schematic view of a current cutoff device at the output of a battery pack;

- Figure 3 is a schematic sectional view of an electrical input terminal according to the invention of the circuit breaker of Figure 1;

- Figure 4 is a schematic sectional view of an alternative embodiment of the electrical input terminal of Figure 2;

- Figure 5 is a schematic sectional view of means for attaching a power supply cable with a storage battery of the current cutoff device of Figure 2;

- Figure 5B is a schematic perspective view of the attachment means of Figure 5;

- Figure 6 is a schematic top view of the circuit breaker of Figure 1; FIG. 7 is a schematic view of part of the electrical circuits of an electronic board of the circuit breaker of FIG. 1; and

FIG. 8 is an opening diagram of the circuit breaker of FIG. 1.

In Figure 1, there is shown a circuit breaker 1 according to the invention. This circuit breaker 1 comprises a parallelepiped-shaped casing 1 A formed by two distinct parts intended to be fitted one above the other to define a housing 1B inside.

On one of its side walls, the housing 1A carries two identical electrical terminals, an electrical input terminal 100 and an electrical output terminal 200, each having a body 101, 201 of elongated shape extending from the inside of the housing. 1 A housing up beyond its side wall.

A first of the ends of each of these bodies 101, 201, that disposed inside the housing 1A, is connected to a contactor element 102,

202 fixed. These two electrical terminals 100, 200 are here made of silver-plated copper.

The two contactor elements 102, 202 have a square section and a small thickness. They form a flat face turned towards the inside of the case

1A. The housing 1 B accommodates all the electrical equipment of the circuit breaker 1. One of these electrical devices is contact means 3 adapted to close or to open the electrical contact between the two electrical terminals 100 and 200 output circuit breaker 1.

These contacting means comprise in particular a contact bridge 3 constituting a U-section beam whose two branches are oriented towards the interior of the housing 1A and whose upper face faces the flat faces of the contact elements 102, 202 of the electrical terminals input 100 and output 200. This contact bridge 3 has a length which allows its upper face to simultaneously be in contact with the two planar faces of the contact elements 102, 202.

The contact bridge 3 also has a central opening for securing it to a movable shaft 2A engaged in this opening.

This movable shaft 2A has at mid-height a flange 4 and at one of its ends a threaded portion. A compression spring 5 is engaged on this The contact bridge 3 is positioned against this compression spring 5. A nut 6 is screwed onto the threaded portion of the movable shaft 2A so as to maintain the bridge of contact 3 against the compression spring 5. The movable shaft 2A is adapted to translate between two stable positions.

In a first stable position, the contact bridge 3 is arranged at a distance from the contacting elements 102, 202, and in a second stable position, the contact bridge 3 bears against these contacting elements. The movable shaft 2A is preferably made of non-magnetic material. A bistable actuating device 2 of cylindrical shape is connected to the movable shaft 2A and is able to move it in translation between its first and second stable positions.

The housing 1A also internally comprises an electronic circuit 10 for controlling the bistable operating device 2. This electronic circuit 10 comprises in particular a microprocessor.

The set of electrical equipment contained in the housing 1A thus makes it possible to open and close the electrical contact of the electrical circuit to which the circuit breaker 1 is connected.

As shown particularly in FIG. 2, this circuit breaker 1 makes it possible to electrically isolate a storage battery 300.

More specifically, the second end of the electrical input terminal 100 of the circuit breaker 1 is connected via a power supply cable 150 to the positive terminal of the storage battery 300 whose negative terminal is connected to an electrical ground. The circuit breaker 1 and the accumulator battery 300 are generally arranged in a battery case 301 fixed to the frame 600 of a motor vehicle which forms this electric mass.

The second end of the electrical output terminal 200 of the circuit breaker 1 is in turn connected by two separate electrical circuits, on the one hand, to a suitable alternator 500, when it is rotated by the main motor (no shown) of said vehicle, to produce an electric current for charging the accumulator battery 300, and, secondly, an electric motor 400 adapted to rotate the main motor of the vehicle to start it. This main engine may for example be an internal combustion engine. As shown in FIG. 3, according to an advantageous characteristic of the circuit breaker 1 according to the invention, for its mechanical and electrical connection to the power supply cable 150, the body 101 of the electrical input terminal

100 is hollow, here over its entire length, and forms, on the side of its second end intended to be connected to said cable, a housing 103 opening for receiving a stripped portion 151 of this cable.

The housing 103 is defined inside a tubular wall 104 of the body

101 having a thickness of about 2 millimeters. The inside diameter of the tubular wall 104 of the body 101 corresponds to the outside diameter of the stripped part of the cable and is generally between 5 and 10 millimeters, here it is equal to 6 millimeters.

This tubular wall 104 is, thanks to its small thickness, capable of being locally plastically deformed so that, once the stripped portion 151 of the power supply cable 150 engaged in the housing of the electrical input terminal 100, it is possible to crimp the power supply cable 150 with the terminal so that they form a one-piece assembly inseparable after crimping.

Advantageously, as shown in FIG. 3, the housing 103 opens out of the body 101 of the electrical input terminal 100 near its first end by a lateral orifice 107 having an axis perpendicular to the axis of said terminal. and about 1 millimeter in diameter. This lateral orifice 107 allows the passage of an electric wire 111. A seal (not shown) can be arranged in this lateral orifice 107 so as to prevent water particles from entering the electrical terminal of entry 100 through this orifice. The body 101 of the electrical input terminal 100 also laterally has two peripheral grooves 108 for receiving an electrical wire 113, 114. These two peripheral grooves 108 are arranged close to the contacting element 102. Shallow depth, about 3 millimeters, and allow to maintain laterally a wire to eventually crimp the bottom of the throat to fix it.

For its connection to the casing 1A of the circuit breaker 1, as shown more particularly in FIG. 3, the body 101 of the electrical input terminal 100 bears on the outer face of its tubular wall 104 a thread 105 adjacent to the element contactor 102 for receiving a fixing nut (not shown). The electrical input terminal 100 is therefore inserted into an opening in the side wall of the casing 1A of the circuit breaker 1 until the contactor element 102 is applied to one of the faces of this side wall. The fixing nut is then screwed onto the thread 105 until it bears against the other face of this side wall. Thus, this side wall is sandwiched between the fixing nut and the contactor element 102 so that the electrical input terminal 100 and the housing 1A form a removable rigid assembly.

According to a first variant not shown of the electrical input terminal, the body of the electrical input terminal may carry a peripheral ring disposed remote from the contact member near which then extends the thread. Thus, the side wall of the housing, for fixing the terminal, is sandwiched between the fixing nut and this peripheral ring so that the contacting element is disposed at a distance from the side wall of the housing of the cutter. circuit. According to a second variant, more particularly illustrated by the figure

4, for its attachment to the side wall of the casing 1A of the circuit breaker, the body 101 of the electrical input terminal 100 externally carries a peripheral ring 106 to be crimped into the side wall of the housing 1A by thermodeforming this wall . In this second variant, the contactor element 102 may also be placed at a distance from the side wall of the casing 1A of the circuit breaker 1.

In these first and second variants, the peripheral grooves 108 and the lateral orifice 107 of the electrical input terminal 100 are, when the latter is secured to the housing 1A, disposed inside the housing 1 A. Thus, according to the configuration of the electrical input terminal and in particular of its fixing means, the lateral orifice 107 and the peripheral grooves 108 may be arranged, when the electrical input terminal 100 is secured to the casing 1A of the circuit breaker 1, either inside the housing 1A or at its side wall. In the latter case, as shown more particularly in Figure 3, the side wall of the housing 1A can be pierced by oblique channels 112 allowing the passage of electrical son 111, 113, 114 into the housing 1A of the circuit breaker 1 while opening on one side, at the orifice 107 or the peripheral grooves 108, and, on the other, inside the housing 1A. However, the method of fixing the power supply cable 150 remains identical to that previously described and is achieved by crimping one end of the cable in the housing 103 of the electrical input terminal 100. Advantageously, as shown in Figures 5 and 5B, the other end of the power supply cable 150 has a second stripped portion 152 fixed by attachment means to the positive terminal 301 of the storage battery 300. These means fasteners constitute a covered terminal 160 having a cylindrical base 162 provided on its side face with a lug 161 adapted to be crimped on the second stripped portion 152 of the power supply cable 150.

The cylindrical base 162 further comprises a cylindrical inner housing 163 of axis coincident with the axis of the cylindrical base 162 and opening on only one of the ends of this base. This inner housing 163 has a diameter and a height substantially equal to the diameter and the height of the positive terminal 301 of the accumulator battery 300.

The cylindrical base 162 is made of a conductive material such as steel but it internally comprises a non-conductive portion 164 disposed on the periphery of the housing 163, the open end of the housing 163 to near the bottom of this housing. Thus, the positive terminal 301 of the accumulator battery 300, to be electrically connected to the power supply cable 150, must be inserted to the bottom of the housing 163 of the covered terminal 160. The connection of other electrical cables intended to supply current to other electrical devices is then impossible to the extent that their fastening means would raise the hooded terminal 160 relative to the positive terminal 301 of the storage battery 300, which would prevent the electrical contact between the positive terminal 301 and the covered terminal 160. These other electrical devices are therefore all connected downstream of the circuit breaker 1. The entire current delivered by the storage battery 300 therefore passes through the circuit breaker before being transmitted to electrical devices, which not only allows precise measurements of the intensity of said current at the input electrical terminal. e 100 of circuit breaker 1 but also allows during a short circuit, to protect all the electrical devices by opening the contact means 3 of the circuit breaker 1.

For fixing the covered terminal 160 to the positive terminal 301 of the storage battery 300, the cylindrical base 162 has a transverse groove 165 extending over its entire height, from its central axis to its outer wall. In addition, the cylindrical base 162 is pierced orthogonally to its transverse groove 165 of a through bore 166 which is threaded on one side of said groove 165. Thus, when a screw is inserted and then screwed into this through bore 166, the two faces opposite the groove 165 are brought closer to each other so that the inside diameter of the housing 163 decreases. Thus, the positive terminal 301 of the accumulator battery 300 is clamped and then secured to the covered terminal 160.

Advantageously, the entire power cut-off device at the output of the storage battery 300 which comprises said battery, the power supply cable 150 and the circuit breaker 1 provided with its input electrical terminal 100 furthermore comprise means for measuring the temperature of the power supply cable 150.

These measurement means comprise in particular a temperature probe 110 inserted into the stripped portion of the power supply cable 150 and then crimped together with the power supply cable 150 to ensure good thermal contact between the probe and the cable. This temperature probe 110 is connected to the electronic card 10 of the circuit breaker 1 by means of an electrical wire 111 which runs in the housing 103 of the electrical input terminal 100 and which leaves it through the lateral orifice 107 practiced near the contactor element 102.

Such a temperature sensor 110 may consist of a resistive sensor CTN or CPT type comprising two son in the same sheath, including a bare wire crimped with the power supply cable, and another possibly isolated wire connected to the card electronic circuit breaker. Alternatively, this electrical wire 111 may be coaxial with a central portion for measuring the temperature and an outer portion for measuring the electrical potential of the second stripped portion 152 of the power supply cable 150. Advantageously, the electrical input terminal 100 comprises means for measuring the voltage between two measurement points which correspond here to the two peripheral grooves 108.

These means for measuring the voltage comprise the two electrical wires 113, 114 which each have an end wound around the electrical input terminal 100, at the bottom of one of the peripheral grooves 108, and another end connected to the electronic card 10 of the circuit breaker 1.

These electric wires are crimped into said peripheral grooves 108 and may, like the electrical wire 111 which connects the temperature probe 110 to the electronic board 10, enter the interior of the housing 1A via the oblique channels. 112.

Alternatively, in order to simplify the fixing of the electrical wires 113, 114, the electrical wire 114 which measures a first electrical potential on the electrical input terminal 100 can be replaced by the electric wire 111 if the latter is coaxial, and the wire electrical 113 which measures a second electrical potential can be replaced by an electrical wire connected to a lug held on the electrical input terminal 100 between the contactor element 102 and the housing 1A of the circuit breaker 1.

In any case, these electrical wires 113, 114 each measure, independently of one another, an electric potential U1, U2 at two different measuring points. The potential difference measured between the two peripheral grooves 108 determines the value of the voltage between these two grooves. This potential difference is in fact non-zero insofar as the electrical input terminal 100 has an internal resistance RO between the two peripheral grooves 108.

As shown more particularly in FIGS. 6 and 7, the circuit breaker 1 comprises means for measuring the intensity of the current delivered by the accumulator battery 300 and passing through the electrical input terminal 100.

These measuring means comprise the means for measuring the voltage between the two peripheral grooves 108 of the electrical input terminal 100 and means for calculating the intensity of the current from said measured voltage.

These calculation means comprise a subtractive operational amplifier 301, each of which is connected to one of the two electrical wires 113, 114. In a manner known per se, the subtractive operational amplifier 301 comprises an operational amplifier 302 powered for its current operation and provided with two input terminals and an output terminal.

The input terminals are connected to the electrical wires 113, 114 via resistors 303, 304 of the same value. The input terminal connected to the electric wire 114 is further connected to the electrical ground via a resistor 305. Furthermore, the input terminal connected to the electrical wire 113 is connected to the output terminal of the operational amplifier 302 via a resistor 306 of equal value to that of the grounded resistor 305.

The ratio between the value of this resistor 305 and that of the resistor 303 connected to the electrical wire 113 determines the gain K of the subtractive operational amplifier 301. Thus, the potential U3 of the output of the subtractive operational amplifier 301 corresponds to the product the gain K of the subtractive operational amplifier 301 and the potential difference measured between the two electrical wires 113, 114 according to the following formula:

U3 = K. (U2-U1), K being the gain of the subtractive operational amplifier 301, U1 and U2 being respectively the potentials of the measurement wires 113, 114, and U3 being the potential of the output terminal of the subtractor operational amplifier 301.

This output terminal is, in the electronic card 10 of the circuit breaker 1, connected to an analog digital converter 310 which digitizes the potential U3 measured at the output of the subtractive operational amplifier 301 so that it can be operated by the microprocessor of the electronic card 10. The microprocessor can then calculate the value of this intensity by performing the following calculation:

I == U3: (K.R0), where I is the value of the intensity of the current passing through the electrical input terminal 100 and RO is the internal resistance of the said electrical input terminal 100 between the two peripheral grooves 108 These measuring means are adapted to measure very low value voltages insofar as the gain K of the subtractive operational amplifier 301 can have a significant value. Moreover, they are also suitable for measuring small intensities since the terminal input electric being hollow, it has a reduced section which increases its internal resistance which then becomes more easily measurable.

Advantageously, the means for measuring the current intensity further comprise an electrical circuit 320 for calibrating the measurement chain of the intensity of the current passing through the electrical input terminal 100. This electrical circuit 320 is indeed useful in that, on the one hand, the subtractive operational amplifier 301 is not perfect so that the potential U3 measured on its output has an inherent error in the operation of the operational amplifier 302, and, on the other hand, on the other hand, there may be variations in the value of the internal resistance RO of the electrical input terminal 100 between the two peripheral grooves 108. Indeed, the temperature variations and inaccuracy in the positioning of the electrical wires 113, 114 may vary substantially the value of this internal resistance RO.

This electrical circuit 320 comprises in series a switch 321 and a resistor 322 of known value; it is connected, on one side, to one of the inputs of the subtractive operational amplifier 301, on the electrical wire 113 whose electrical potential is measured, and, on the other, to the electrical ground (identical to that on which the negative terminal of the accumulator battery 300) is connected. The switch 321 here is an electrical transistor.

The resistor 322 has a value of 10 ohms which advantageously is at least ten times greater than the value of the internal resistance RO of the electrical input terminal 100 between the two peripheral grooves 108. This resistor 322 has a lower thermal sensitivity at 0.005% per degree so that differences in temperature have little effect on the measurement result.

The method of measuring a precise value of the intensity of the current comprises different steps. During a first step, the switch 321 being open, the processor calculates using the formulas mentioned above an approximate value of the intensity of the current passing through the electrical input terminal 100. It also notes a first potential of the electric wire 113. Then, during a second step, it controls the closing of the switch 321. During a third step, it calculates again the intensity of the current passing between the two peripheral grooves 108 of the electrical input terminal. Part of the current passing through the electrical circuit 320, the result of the calculation is different. It also raises a second potential of the electrical wire 113. Finally, during a fourth and last step, knowing the exact value of the resistor 322 of the electrical circuit 320, it compares the two intensities calculated and the difference between the two potentials. measured on the electrical wire 113, and determines a refined value of the intensity of the current passing through the electrical input terminal.

In such a way that the variations of current due to the variations of the electricity requirements of the electrical equipment of the vehicle do not distort the calculations, this closing of the switch 321 can be carried out regularly, for example every 50 milliseconds, so that the conditions between the first and third steps of the method are substantially identical. Another method making it possible to ensure that the calculations are not distorted consists in opening the contact means 3 before carrying out the measurement steps mentioned above.

The electronic card 10 then stores in memory in memory means, for a given temperature measured by the temperature sensor 110, the correction value of the intensity of the current.

Thus, subsequently, when the temperature measured by the temperature probe 110 has already been met, the electronic card 10 can determine by a simple calculation the refined value of the intensity of the current as a function, on the one hand, of the approximate value of the intensity of the current calculated by the subtractive operational amplifier 301, and, secondly, the correction value stored by the storage means. The use of the switch 321 is therefore reduced to cases where the temperature has not yet been encountered. The calibration of the measurement chain of the intensity of the current passing through the electrical input terminal 100 can then, thanks to these storage means, be implemented regularly and not continuously. According to an advantageous characteristic of the circuit breaker 1, its electrical output terminal 200, identical to its electrical input terminal 100, carries in one of its peripheral grooves an electrical wire 213 which, using a suitable device, 330 such as a voltmeter connected to an analog digital converter, to measure an electric potential at this point of the terminal. This electrical wire 213 is connected to the electronic card 10 which comprises means for comparing one of the potentials measured on the electrical input terminal 100 and the potential measured on the output electrical terminal 200. These comparison means, as a function of the As a result of this comparison, it can be deduced, on the one hand, whether the contact bridge 3 is in the open or closed position, and, on the other hand, when the contact bridge 3 is in the closed position, the state of wear contact means. Thus, if a significant potential difference characteristic of premature wear of the contact means is detected, the circuit breaker can inform the driver of the vehicle, for example by means of a light emitting diode disposed on the dashboard. of the vehicle. In the same way, the comparison means are adapted to detect micro-cuts of the current between the two electrical input and output terminals 200, said microcuts being characteristic of poor attachment of the power supply cable 150 to the battery. of accumulators 300 or the electrical input terminal 100. If it detects such micro-cuts, it can also inform the driver of the vehicle.

Advantageously, the electronic circuit 10 also comprises means for calculating the internal resistance of the accumulator battery 300. These calculation means are located in the microprocessor of the battery switch 1; they are adapted to deduce, on the one hand, the variation, when the switch opens and closes, of the electric potential measured on one of the electric wires 113, 114, and, on the other hand, the value of the internal resistance of the power supply cable 150, the value of the internal resistance of the accumulator battery 300. The value and increase of this internal resistance indicating the remaining life of the accumulator battery 300 connected to the cutter -circuit 1, the electronic circuit 10 can also provide the driver of the vehicle an end of life indication of the accumulator battery 300.

According to an advantageous characteristic of the invention, as shown more particularly in the diagram of FIG. 8, the electronic circuit 10 comprises means for determining at least one value of a parameter associated with the electric current flowing through the circuit breaker 1 in operation.

These determination means comprise means for measuring at least one value of a quantity associated with said parameter. These means of measurement can comprise either all means for measuring the current passing through the electrical input terminal 100 of the circuit breaker 1, or only the means for measuring the voltage between the two peripheral grooves 108 of the terminal. Said value of the magnitude may therefore be a voltage, an electric potential or an intensity.

The determination means also comprise calculation means which read the value of the quantity measured by the measuring means in order to determine the value of the parameter associated with said quantity. This parameter is chosen to be characteristic of a short circuit. This parameter may for example be an intensity, a voltage drop speed or a potential drop speed.

The electronic card 10 also comprises means for storing at least one threshold value of at least one parameter associated with the electric current flowing through the circuit breaker. These threshold values are implemented during the manufacture of the electronic card 10 and therefore do not vary. They concern here maximum values that the parameters determined by the determination means must not exceed.

The threshold values can for example be, when the current is delivered by the accumulator battery 300 to power the motor 400 starting motor of the main motor of the vehicle, 2000 amps for 1 second, 1500 amps for 5 seconds, 1000 amps for 15 seconds, 500 amps for 60 seconds, and 0.1 volts per second.

They may have different values when the current is delivered by the alternator 500 to recharge the accumulator battery 300. They can then be 200 amperes for 1 seconds.

These values are variable depending on the type of battery for which the circuit breaker 1 is intended.

The electronic card 10 also comprises means for comparing the values determined by the determination means and threshold values associated with them. Here, these means compare in real time not only the value of the voltage drop speed with the threshold value associated with it, but also the intensity of the current flowing in the input electrical terminal 100 with the different threshold values which are associated with it. Thus, as soon as at least one of the values of a parameter determined by the determination means exceeds the threshold value associated with it, the comparison means of the electronic card 10 provide information to processing means able to transform this parameter. information in an order to open the contact bridge 3.

Therefore, as soon as a short circuit is detected by the circuit breaker 1, the latter quickly cuts the electrical contact at the output of the accumulator battery 300 so as to electrically isolate it to protect the accumulator battery 300 and the electrical apparatus that it supplies or to protect the electric alternator 500 if the short circuit comes from the accumulator battery 300.

Advantageously, the circuit breaker 1 comprises inside the housing 1A shock detection means and inclination detection means.

These detection means are sensors that are electrically connected to the electronic card 10 and send an electrical signal when they detect an impact greater for example 10 G or inclination of the upper housing for example 15 degrees. Such shock or inclination means that the vehicle provided with the circuit breaker 1 has suffered an accident, which increases the probability of a short circuit appears. In this case, the electronic card 10 is adapted to lowering the values of the set of threshold values (for example to 200 amperes for one second, whatever the direction of the current) so as to more effectively prevent the occurrence of any short circuit. .

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

Claims

1. A circuit breaker (1) having an electrical input terminal (100) which is intended to be connected to a storage battery (300) and which has a body (101) connected at one end to an element fixed contactor (102), an electrical output terminal (200), contact means (3) adapted to close or open the electrical contact between the two input (100) and output (200) electrical terminals cooperating with each other. with said contacting element (102), and current measuring means (113, 114, 301, 320) passing through the input electrical terminal (100), characterized in that the current measuring means comprise, on the one hand, means for measuring the voltage (113, 114, 301) between two measuring points (108) of the electrical input terminal (100) and means for calculating the intensity of the current from said voltage, and, on the other hand, an electrical circuit (320) comprising in series a switch (321) and a resistor (322) of known value, said electrical circuit (320) being connected on one side to a known potential point and on the other to one of said measuring points (108) which is disposed near the contactor element (102) and whose potential is measured by the voltage measuring means (113, 114, 301).

2. Circuit breaker (1) according to claim 1, characterized in that the electrical input terminal (100) comprises a body (101) hollow.

3. Circuit breaker (1) according to one of claims 1 and 2, characterized in that the voltage measuring means comprise two electrical son (113, 114) connected on one side to one of the measuring points ( 108), and on the other to one of the inputs of a subtractive operational amplifier (301).

4. Circuit breaker (1) according to one of claims 1 to 3, characterized in that the switch (321) is an electrical transistor.

5. Circuit breaker (1) according to one of claims 1 to 4, characterized in that the known potential point is connected to the electrical ground of the circuit breaker

(1).

6. Circuit breaker (1) according to one of claims 1 to 5, characterized in that the value of said resistor (322) is at least ten times greater than the value of the internal resistance (RO) of the electrical terminal input (100) between said two measuring points (108).

7. Circuit breaker (1) according to one of claims 1 to 6, characterized in that it comprises means (330) for measuring an electrical potential at a point of the electrical output terminal (200).

8. Circuit breaker (1) according to claim 7, characterized in that it comprises means for comparing the electrical potentials measured on the electrical input (100) and output (200) terminals.

9. Circuit breaker (1) according to one of claims 7 and 8, characterized in that the electrical output terminal (200) comprises a hollow body.

10. A method of measuring an electric current delivered by a storage battery (300) and passing through an electrical input terminal (100) of a circuit breaker (1) according to one of claims 1 to 9 characterized in that it comprises the steps of:

- recording a first potential difference measured by the voltage measuring means (113, 114, 301) and a first potential of the measuring point (108) to which the electrical circuit (320) is connected;

calculating, as a function of the value of the internal resistance (RO) of the electrical input terminal (100) between the two measurement points (108) and of the first measured potential difference, the approximate value of the intensity (I) the current flowing through the input electrical terminal (100); - close the switch (321);

- reading a second potential difference measured by the voltage measuring means (113, 114, 301) and a second potential of the measuring point (108) on which is connected the electric circuit (320);

calculating, as a function of the variation between the first and second measured potential differences, the variation between the first and second potentials of the measuring point (108), and the approximate value of the intensity (I) of the calculated current a refined value of the intensity (I) of the current flowing through the input electrical terminal (100); and

- open the switch (321).

11. Measuring method according to claim 10, characterized in that the temperature of the electrical input terminal (100) is measured and a value of the difference between the approximate value and the refined value of the intensity is stored ( I) the current passing through the electrical input terminal (100) with which said temperature is associated.

12. Measuring method according to one of claims 10 and 11, characterized in that determines an internal resistance of a power supply cable (150) connected between the storage battery (300) and the electrical terminal input (100) and the value of the internal resistance of the accumulator battery (300) is calculated as a function of said internal resistance and the variation between the first and second measured potential differences.

13. Measurement method according to one of claims 10 to 12, characterized in that, prior to the implementation of said steps, the contact means (3) is opened.

14. Method for determining the state of contact means (3) of a circuit breaker (1) according to one of claims 7 to 9, characterized in that the values of electrical potentials measured by the measuring means (113, 114, 301) on the electrical input (100) and output (200) terminals, and the open or closed position of the contact means (3) is deduced therefrom.

15. Determination method according to claim 14, characterized in that values of the electrical potentials measured by the measuring means (113, 114, 301) are deduced from the electrical input (100) and output (200) terminals. ), the state of wear of the contact means (3).