Patent Description:
Electrical power connectors are used in electric or hybrid motor vehicles, for example to charge batteries from a recharging station, to interconnect a set of batteries to an electric motor, to a power converter, etc..

In hybrid and electric motor vehicles, the electric currents transmitted by the cables and the connectors of the electrical power circuits are relatively high, and may reach <NUM> amperes, or even more than <NUM> amperes at current peaks. Such currents may generate overheating in the connectors.

It is therefore important to be able to limit this risk of overheating and/or to disconnect the supply of power current transmitted by the connector in the event of overheating and/or to provide information that overheating has taken place in order to prompt an inspection of the electrical circuit in which this overheating has occurred.

Solutions involving integrating temperature probes in the connectors are known. Temperature probes, such as thermocouples for example, may be relatively expensive, all the more so since it is necessary to use an electronic circuit to perform and interpret the measurement at the terminals thereof. Other solutions involve integrating in the connector a fuse supplied by a low-voltage current (see for example <CIT>). Temperature probes, such as thermal fuses, have specific shapes that may pose problems in terms of integrating them in a connector. Furthermore, even though the information given by a temperature probe or a fuse indicates that overheating has occurred, this does not necessarily prevent continued use of the connector, which potentially poses a safety problem. Documents <CIT> discloses an electrical connector according to the preamble of claim <NUM>.

The present disclosure proposes an alternative to the existing solutions.

To this end, what is proposed is an electrical connector according to claim <NUM>. In one exemplary embodiment, described in detail below, the first low-voltage electrical line is configured so as to be electrically linked, connected, to an interlock control circuit of a high-voltage circuit (also called "HVIL" or "high-voltage interlock loop"). Interlock control loops or circuits are used in connectors to detect coupling or decoupling of a connector and a mating connector, and trigger or disconnect the supply of electric power in power contacts housed in the connector and the mating connector. The second low-voltage electrical line may comprise for example one or more shielding elements. In this case, the second conductive component may be a shielding element attached to the housing, such as a shielding metal sheet assembled to the housing. The shielding element makes it possible to at least partially screen the electromagnetic waves produced by the flow of high currents in the cables and the contacts housed in the connector housing. The shielding element is in electrical continuity firstly with the shielding braid of each cable and/or with a shielding sheath surrounding multiple cables, and secondly with the shielding of a mating connector and/or a conductive wall on which the connector is installed.

The solution involving using a low-voltage line already provided for another function (interlock circuit or shielding) makes it possible to provide a function of detecting potential overheating in a power connector, without notably complicating the manufacture and the installation of such a connector, since this does not require adding in particular contacts and/or electrical wires dedicated to this detection.

The first conductive component may be an electrical contact, an electrical contact blade, a shunt, a spring or any other element configured so as to be connected, linked or integrated electrically to or in the first low-voltage line.

The electrical connector furthermore comprises at least one electrically insulating element and at least one electrically conductive element, inserted between the first conductive component and the second conductive component. In other words, the electrically insulating element may be inserted either between the electrically conductive element and the first conductive component, or between the electrically conductive element and the second conductive component, or both between the electrically conductive element and the first conductive component on one side, and between the electrically conductive element and the second conductive component on another side. The insulating element consists of a material having a melting temperature less than or equal to the melting temperature of at least one of the materials forming the housing. For example, the insulating element consists of a material having a melting temperature of between <NUM> and <NUM>. The insulating element may possibly also be characterized by a glass transition temperature or any other property that takes account of its ability to deform under the combined effect of a temperature and a mechanical stress.

Specifically, the electrically conductive element exerts an elastic force on the insulating element that is suitable for deforming the electrically insulating element, when the electrically insulating element reaches a given temperature, for example a temperature greater than or equal to its melting temperature. Following this deformation, the electrically conductive element establishes an electrical connection between the first conductive component and the second conductive component. This results for example in a short circuit between the first and second low-voltage lines, which may for example be reflected by grounding of the first low-voltage line, etc..

Thus, if excessive overheating occurs in the connector, the insulating element softens, or even melts at least locally, and the electrically conductive element that exerts a pressure on the insulating element deforms it until electrical contact is established with the first conductive component, on the one hand, and the second conductive component, on the other hand, thus creating an electrical link between them. This results in a modification of the voltage on the first low-voltage line and/or the second low-voltage line. This modification constitutes a signal that makes it possible to detect the overheating. Following this detection, the information may be displayed on the dashboard of the vehicle in order to signal that the vehicle should be taken for repair and to change the detection device comprising the insulating element that has melted, and the power current flowing through the conductor can, as an alternative or in addition, possibly be interrupted.

In any case, it may be advantageous for the modification that occurs between the first and second low-voltage lines in the event of overheating to take the connection assembly, or at least the connector or the mating connector, out of service. For example, when one of the low-voltage lines is connected to an interlock control circuit, grounding this line renders this circuit inoperative, without thereby implementing any electrical signal processing operation. In other words, the taking of the connection assembly, the connector or the mating connector out of service in this case does not result from any calculation or from the processing of a signal; it is the direct consequence of the material event (short circuit or grounding) resulting from the overheating that led to the deformation of the electrically insulating element. It will be noted that, in the same way as overheating is a critical event that risks damaging a connector housing made of plastic, overheating is at the origin of the deformation of the electrically insulating element. In other words, it is the same phenomenon that is used to detect overheating as that which is at the origin of the problem that it is desired to avoid. This therefore gives a consistent and reliable overheating detection method.

Furthermore, the deformation of the electrically insulating element is an irreversible event that requires all or part of the connection assembly in which it is placed to be replaced. This represents an advantage on a safety level.

The material of the electrically insulating element is therefore chosen according to its melting temperature, which defines the acceptable limit for the connector, the mating connector, the connection assembly or else components thereof or neighbours thereof.

This connector also possibly comprises one and/or the other of the following features, each considered independently of one another or in combination with one or more others:.

According to another aspect, what is proposed is a connection assembly comprising a connector as mentioned above, and a mating connector comprising a housing that houses signal contacts that are configured so as to be integrated in the first low-voltage line. These contacts are connected to the first conductive component when the connector and the mating connector are coupled.

According to yet another aspect, what is proposed is a method for detecting overheating in an electrical connection assembly according to claim <NUM>, wherein the deformation of an electrically insulating element made of plastic, under stress from an electrically conductive element, is used to modify an electrical circuit. For example, the deformation of an electrically insulating element made of plastic, under stress from an electrically conductive element, is used to establish an electrical connection between at least one first conductive component configured so as to be integrated in a first low-voltage electrical line and at least one second conductive component configured so as to be integrated in a second low-voltage electrical line, the setting up of this connection producing a change in the voltage on the first low-voltage line and/or the second low-voltage line, which constitutes a signal for detecting overheating.

For example, this method comprises an operation of collecting a signal by taking a series of electrical measurements on a first low-voltage line. This method furthermore comprises an operation of monitoring, over time, whether the signal collected in the course of the series of electrical measurements taken on the first low-voltage line undergoes a variation following a connection of the first low-voltage line to a second low-voltage line, this connection being the consequence of the deformation of the electrically insulating element.

The method possibly comprises an operation in which a first conductive component is connected to an interlock control circuit of a high-voltage circuit and the variation of the signal occurs following a connection of the first conductive component to a shielding element of the connector, by way of the electrically conductive element.

Other features and advantages of the invention will become apparent on reading the following detailed description, and from the appended drawings. In these drawings:.

One example of a connection assembly <NUM> is shown schematically in <FIG>. This connection assembly comprises a connector <NUM> configured so as to be coupled to a mating connector <NUM>, parallel to a coupling direction A.

The connector <NUM> is a cable connector. The mating connector <NUM> is a receptacle configured so as to be installed on a wall <NUM> through which it passes. According to this example, the connector <NUM> is a female connector and the mating connector <NUM> is a male connector.

The connector <NUM> comprises in particular a housing <NUM>, power contacts <NUM>, a conductive component <NUM>, a shielding element such as a shielding cage <NUM> and a passive detection device <NUM> for passively detecting potential overheating.

The housing <NUM> of the connector <NUM> is formed of one or more elements made of insulating plastic. The power contacts <NUM> are housed in chambers formed in the housing <NUM>. These are female power contacts that are each respectively electrically connected to a cable <NUM>. In this example, the conductive component <NUM> is an electrical contact blade with two flexible contact tabs <NUM> that are electrically connected to one another so as to form a shunt. The shielding cage <NUM> consists of one or more metal sheets made of electrically conductive material. The shielding cage <NUM> is configured so as to at least partially screen the electromagnetic waves generated by the flow of high currents through the connection assembly <NUM>. The shielding cage <NUM> is in electrical contact with the individual shielding braids of the cables <NUM> (and/or with a shielding sheath common to multiple cables <NUM>, this configuration not being shown).

The mating connector <NUM> comprises in particular a housing <NUM>, power contacts <NUM>, signal contacts <NUM> and a shielding element such as a shielding cage <NUM>.

The housing <NUM> of the mating connector <NUM> is formed of one or more elements made of insulating plastic. The power contacts <NUM> are housed in chambers formed in the housing <NUM>. These are male power contacts that are each respectively electrically connected to a cable <NUM>. The signal contacts <NUM>, of which there are two, are each respectively connected to an interlock control circuit <NUM> by electrical wires <NUM>. The signal contacts <NUM> and the electrical wires <NUM> are therefore integrated in a first low-voltage electrical line. The interlock control circuit <NUM> controls the opening and the closure of the high-voltage circuit comprising the power contacts <NUM> of the mating connector <NUM>.

The shielding cage <NUM> consists of one or more metal sheets made of electrically conductive material. The shielding cage <NUM> is configured so as to at least partially screen the electromagnetic waves generated by the flow of high currents through the connection assembly <NUM>. The shielding cage is in electrical contact with the individual shielding braids of the cables <NUM> (and/or with a shielding sheath common to multiple cables <NUM>, this configuration not being shown). The shielding cage <NUM> is also in electrical contact with the wall <NUM>, which is itself connected to the ground of the vehicle.

The shielding cages <NUM>, <NUM> are therefore intended to participate in a second low-voltage electrical line connected to the ground of the vehicle. As an alternative, the shielding cages <NUM>, <NUM> are integrated in a low-voltage electrical line that is not connected to the ground of the vehicle.

When the connector <NUM> and mating connector <NUM> are coupled, the male power contacts <NUM> and female power contacts <NUM> are connected in pairs, the signal contacts <NUM> are connected to the conductive component <NUM>, thereby closing the loop of the interlock control circuit <NUM>, and the respective shielding cages <NUM>, <NUM> of the connector <NUM> and mating connector <NUM> are in electrical contact with one another (thereby also potentially making it possible to connect the cage of the connector to the ground of the vehicle).

When the connector <NUM> and mating connector <NUM> are coupled, the interlock control circuit <NUM> controls and triggers the supply of power to the power contacts <NUM> (<FIG>). Without overheating, the detection device <NUM> electrically insulates the conductive component <NUM> from the shielding cage <NUM> of the connector <NUM>. The first and second low-voltage electrical lines are isolated from one another.

In the event of overheating of the connector <NUM> and/or the mating connector <NUM>, the detection device <NUM> deforms and connects the conductive component <NUM> to the shielding cage <NUM> of the connector <NUM> (<FIG>). The interlock control circuit <NUM> detects a variation in the signal measured on the loop of the interlock control circuit <NUM>. For example, before overheating, the interlock control circuit <NUM> continuously measures a voltage that corresponds to a resistance R, representing the resistance of the electrical wires <NUM>, of the signal contacts <NUM> and of the conductive component <NUM>, and the contact resistances between these various elements. After overheating, the interlock control circuit <NUM> measures a voltage that corresponds to a resistance R', representing the resistance of one of the electrical wires <NUM>, of one of the signal contacts <NUM>, of part of the conductive component <NUM> and of the detection device <NUM>, and the contact resistances between these various elements. The variation between R and R' is enough to signal a change of configuration in the detection device <NUM>, this change resulting from overheating in the connection assembly <NUM>. As an alternative, grounding the interlock control circuit renders it inoperative, thereby possibly causing the disconnection of the supply of power to the power contacts <NUM>, <NUM>.

The change of configuration of the detection device <NUM> is shown schematically in <FIG>. In <FIG>, before overheating, there is no connection (practically infinite resistance in the detection device <NUM>) between the loop <NUM> of the interlock control circuit <NUM> and the line <NUM> incorporating the shielding cage <NUM> (the first low-voltage electrical line <NUM> and second low-voltage electrical line <NUM> are isolated from one another). In <FIG>, after overheating, the detection device <NUM> connects the loop <NUM> of the interlock control circuit <NUM> and the line <NUM> incorporating the shielding cage <NUM> (the first low-voltage electrical line <NUM> and second low-voltage electrical line <NUM> are connected to one another).

One particular exemplary embodiment of a connector <NUM> is described with reference to <FIG> (<FIG>).

According to this example, the connector <NUM> comprises an internal housing element <NUM>, an external housing element <NUM>, two shielding metal sheets <NUM>, <NUM> forming the shielding cage <NUM>, a conductive component <NUM>, a detection device <NUM>, and a coupling assistance device <NUM>.

The shielding metal sheets <NUM>, <NUM> are inserted between the internal housing element <NUM> and external housing element <NUM>.

The detection device <NUM> comprises an electrically conductive element <NUM> and an electrically insulating element <NUM> (<FIG>). The electrically conductive element <NUM> is a helical spring. The axial force Fx supplied by the electrically conductive element <NUM> is for example between <NUM> and <NUM> newtons. The electrically conductive element <NUM> is installed in a support <NUM>. In the exemplary embodiment shown in <FIG>, the support <NUM> is integral with the electrically insulating element <NUM>, and consists of a material having a melting temperature of between <NUM> and <NUM>. For example, said melting temperature is equal to or close to <NUM>. For example, this polymer material is a polypropylene, a polyethylene or an epoxy.

The support <NUM> and the electrically insulating element <NUM> form one part having a U-shaped cross section. One of the branches of the U comprises an opening <NUM> for the passage of the electrically conductive element <NUM> (see <FIG>). The other branch of the U corresponds to the insulating element <NUM> on which the electrically conductive element <NUM> bears and exerts a pressure corresponding to the axial force Fx.

When the detection device <NUM> is installed in the connector <NUM>, the support <NUM> is surrounded in a recess formed in the internal housing element <NUM> of the connector <NUM>, such that the electrically conductive element <NUM> is in electrical contact, via one of its axial ends, with the conductive component <NUM> (and more particularly one of its flexible tabs <NUM>) and is insulated, at the other axial end, from the shielding metal sheet <NUM> by the insulating element <NUM> (<FIG>).

The electrically insulating element <NUM> is therefore inserted between the electrically conductive element <NUM> and the shielding metal sheet <NUM>. The thickness E of the electrically insulating element <NUM> thus inserted is for example between <NUM> millimetres and <NUM> millimetres. For example, this thickness E is equal to or close to <NUM> millimetres.

Thus, in the event of overheating, that is to say if the temperature in the connector becomes for example greater than or equal to <NUM>, the insulating element softens and, under the effect of the pressure exerted by the electrically conductive element <NUM> on the electrically insulating element <NUM>, the electrically conductive element <NUM> passes through the electrically insulating element <NUM> and establishes electrical contact with the shielding metal sheet <NUM>.

It is possible to conceive of other variants of the detection device <NUM> described above. For example, an electrically insulating element <NUM> similar to the one described above may be inserted between the electrically conductive element <NUM> and the conductive component <NUM>. As an alternative, the electrically insulating element <NUM> is inserted between the electrically conductive element <NUM> on one side and between the electrically conductive element <NUM> and the shielding cage <NUM> on another side.

Likewise, the shielding element may be formed of something other than a metal sheet (for example a housing element on which a conductive layer is deposited).

Likewise, the electrically conductive element may be other than a spring (for example a component that expands under the effect of heat).

The detection device may be installed in the mating connector <NUM>, rather than in the connector <NUM>, or else in the connector <NUM> and the mating connector <NUM>.

Rather than a connection device <NUM> that makes it possible to connect two power cables <NUM>, <NUM> in pairs, the connection device <NUM> may be designed to connect a single cable or more than two cables.

Claim 1:
Electrical connector (<NUM>) comprising
- a housing (<NUM>) that houses at least one first conductive component (<NUM>) configured so as to be integrated in a first low-voltage electrical line and at least one second conductive component (<NUM>) configured so as to be integrated in a second low-voltage electrical line,
- at least one electrically insulating element (<NUM>) and at least one electrically conductive element (<NUM>), inserted between the first conductive component (<NUM>) and the second conductive component (<NUM>),
the electrically insulating element (<NUM>) consisting of a material having a melting temperature less than or equal to the melting temperature of at least one of the materials forming the housing (<NUM>), and
characterized in that
- the electrically conductive element (<NUM>) exerts an elastic force on the electrically insulating element (<NUM>) that is suitable for deforming the electrically insulating element (<NUM>), when the electrically insulating element (<NUM>) has a temperature greater than or equal to its melting temperature and establishing an electrical connection between the first conductive component (<NUM>) and the second conductive component (<NUM>).