Mains plug and charging system for a motor vehicle

A mains plug for connecting a charging system of a motor vehicle to a socket outlet of an alternating current network comprises a contact housing having a first gripping area and a sensor unit having a first sensor electrode embedded in the contact housing. A first section of the contact housing is arranged between a first surface of the first gripping area and the first sensor electrode.

FIELD OF THE INVENTION

The present invention relates to a charging system and, more particularly, to a mains plug of a charging system.

BACKGROUND

A charging system, specifically for electric vehicles, having a charging device-side plug-in connector and a sensor is known from German Patent Application No. 202009013675 U1. The sensor emits a signal if a human body part approaches the plug-in charging system and/or if a human body part touches the plug-in charging system.

SUMMARY

A mains plug for connecting a charging system of a motor vehicle to a socket outlet of an alternating current network comprises a contact housing having a first gripping area and a sensor unit having a first sensor electrode embedded in the contact housing. A first section of the contact housing is arranged between a first surface of the first gripping area and the first sensor electrode.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

In the following figures, reference is made to a coordinate system5. The coordinate system5is configured as a right-handed coordinate system, and has a x-axis, a y-axis and a z-axis.

A charging system10according to an embodiment for charging an electrical energy accumulator15of a motor vehicle20is shown inFIG.1. The motor vehicle20can be configured as a hybrid vehicle or as an electric vehicle; at least part of the propulsion energy is stored in the electrical energy accumulator15of the motor vehicle20. The electrical energy accumulator15can be, for example, a lithium-air accumulator. In other embodiments, the electrical energy accumulator15may be configured in a different form.

The charging system10, as shown inFIG.1, comprises a charging device25. In an embodiment, the charging device25is installed in the motor vehicle20and executes the control and/or regulation of a process for the charging of the electrical energy accumulator15with electrical energy from a permanent electrical network, such as a permanent alternating current network.

The charging system10, as shown inFIG.1, comprises a first vehicle terminal30, which is arranged in the motor vehicle20. The charging device25is electrically connected to the electrical energy accumulator15of the motor vehicle20by a first connection35. The charging device25is electrically connected to the first vehicle terminal30by a second connection40.

The charging system10, as shown inFIG.1, comprises a mains plug45, a monitoring circuit55, and a second vehicle terminal65. The mains plug45, the monitoring circuit55, and the second vehicle terminal65are configured in a stationary arrangement and, in the shown embodiment, are not installed in the motor vehicle15.

As shown inFIG.1, the mains plug45comprises a first cable50and the monitoring circuit55comprises a second cable60. The first cable50comprises a first electrical conductor70, an exemplary second electrical conductor75, a first protective conductor80, and a signal line85. The first electrical conductor70, the second electrical conductor75, the first protective conductor80and the signal line85are configured in the first cable50in a mutually electrically insulated arrangement. The second cable60incorporates a third electrical conductor90, a fourth electrical conductor95, and a second protective conductor100.

The mains plug45connects the charging system10to a socket outlet110of the permanent electrical network. The first vehicle terminal30is connected to the second vehicle terminal65, and thus constitutes an electrical coupling between the first vehicle terminal30and the second vehicle terminal65.

A mains plug45of the charging system10shown inFIG.1is shown inFIGS.2and3. The mains plug45comprises a contact housing115, a first contact element120, a second contact element125, a protective contact130, and a sensor unit135.

As shown inFIG.2, the first contact element120and the second contact element125each have a pin-shaped design and extend in the x-direction. The first contact element120is arranged offset in relation to the second contact element125in the z-direction. The first contact element120is electrically connected to the first electrical conductor70and the second contact element125is electrically connected to the second electrical conductor75. The first contact element120and the second contact element125are arranged on a side of the contact housing115which faces the socket outlet110.

The first contact element120, as shown inFIG.2, has a first pin section141and a first contact element section142. The second contact element125has a second pin section143and a second contact element section144. The first contact element section142and the second contact element section144are embedded in the contact housing115. The first pin section141of the first contact element120and the second pin section143of the second contact element125project from the contact housing115, on an end face of the contact housing115which faces the socket outlet110, outwardly from the contact housing115. The pin sections141,143extend in a plug-in direction (x-direction) of the contact element120,125, such that the pin section141,143is inserted in a jack socket of the socket outlet110which is respectively assigned to the pin section141,143. The contact element120,125is mechanically attached to the contact housing115by the contact element section142,144. In an embodiment, the first electrical conductor70can be connected to the first contact element section142, and the second electrical conductor75can be connected to the second contact element section144.

On a circumferential side, as shown inFIG.2, the first pin section141has a first contact surface136and, on a circumferential side, the second pin section143has a second contact surface137. If the mains plug45is inserted in the socket outlet110, the first contact surface136forms a first electrical contact with a first jack socket of the socket outlet110. With the mains plug45in the plugged-in state in the socket outlet110, the second contact surface137forms a second electrical contact with a second jack socket of the socket outlet110.

The contact housing115, as shown inFIGS.2and3, has a first housing region145, a second housing region150, and a third housing region146. The third housing region146is arranged in the x-direction between the first housing region145and the second housing region150. On the second housing region150, the contact housing115has a first gripping area155and a first projection160on a first lateral surface157, and a second gripping area165and a second projection170on a second lateral surface158, arranged opposite the first lateral surface157. In the x-direction, the first gripping area155and the second gripping area165are arranged at the same height. In the z-direction, the first gripping area155and the second gripping area165are arranged with a mutual clearance. The gripping area155,165is delimited on a side facing the contact element120,125by the third housing region146.

The third housing region146, as shown inFIGS.2and3, has an exemplary cup-shaped design and tapers from the first housing region145in the direction of the second housing region150. In the z-direction, the second housing region150has a narrower dimension than the first housing region145. On a side which is opposite the contact element120,125, the first gripping area155is delimited by the first projection160and the second gripping area165is delimited by the second projection170. The projection160,170is arranged with a clearance of approximately one finger's width from an upper end of the third housing region146in the x-direction. The projection160,170extends in the z-direction. The function of the projection160,170is to permit the particularly effective gripping of the body component, thereby facilitating the withdrawal of the first housing region145and the contact element120,125from the socket outlet110.

The protective contact130, as shown inFIGS.2and3, is arranged laterally on the first housing region145of the contact housing115which is configured to match the socket outlet110. In the fitted state of the mains plug45in the socket outlet110, the first housing region145is circumferentially enclosed by the socket outlet110. The protective contact130is electrically connected to the first protective conductor80.

As shown inFIG.3, the second projection170extends in the z-direction, in the opposite direction to the first projection160. The first gripping area155and/or the first projection160, and the second gripping area165and/or the second projection170, are arranged with mirror-image symmetry to a plane of symmetry175, which is arranged between the first gripping area155and the second gripping area165and is, for example, an xy-plane. The plane of symmetry175is centrally arranged between the first contact element120and the second contact element125. By the opposing arrangement, a reliable gripping of the mains plug45is ensured. The projection160,170, at least in part, is configured transversely to the plug-in direction (x-direction) of the contact element120,125.

The gripping area155,165, as shown inFIGS.2and3, is essentially arranged in parallel to the plug-in direction of the contact element120,125. The first projection160incorporates a first projection outline195and the second projection170incorporates a second projection outline200. The first projection outline195and/or the second projection outline200can be configured, for example, with an L-shaped or U-shaped design.

The sensor unit135, as shown inFIGS.2and3, has a sensor circuit180, a first sensor electrode185, and a second sensor electrode190. The sensor electrode185,190can comprise, for example, a wire and/or a leadframe and/or an electrically-conductive plastic. The first sensor electrode185and the second sensor electrode190can be arranged on a common leadframe, or on a leadframe which is respectively assigned to each of the sensor electrodes185,190. In an embodiment, the sensor circuit180, the first sensor electrode185, and the second sensor electrode190are arranged on a common leadframe. The sensor unit135is completely embedded in a material of the contact housing115. The material is, for example, electrically insulating, and is a plastic in an embodiment.

During the manufacture of the mains plug45, the sensor electrode185,190and the sensor circuit180are molded with the material of the contact housing115, in an injection mold. The first sensor electrode185is arranged adjacently to the first projection160, at an equal height in the x-direction. The second sensor electrode190is arranged adjacently to the second projection170, at an equal height in the x-direction.

In an embodiment, the sensor electrode185,190can be configured with a meander-shaped design. As shown inFIG.2, the first sensor electrode185is at least partially arranged in parallel with the first projection outline195, and the second sensor electrode190is at least partially arranged in parallel with the second projection outline200.

The contact housing115, as shown inFIG.3, has a first section210between a first surface205of the first gripping area155and the first sensor electrode185. The first section210electrically insulates the first sensor electrode185from the first gripping area155. The contact housing115has a second section220between a second surface215of the second gripping area165and the second sensor electrode190. The second section220electrically insulates the second sensor electrode190from the second surface215. The contact housing115has a third section225between the first sensor electrode185and the second sensor electrode190. The third section225electrically insulates the first sensor electrode185from the second sensor electrode190.

The first sensor electrode185is arranged in a first area227, as shown inFIG.3, in a first plane. The first area227is arranged in parallel with the first surface205. The second sensor electrode190is arranged in a second area226, in a second plane. The second area226can be arranged in parallel with the first area227of the first sensor electrode185. The second area226is arranged in parallel with the second surface215.

A circuit diagram of the charging system10is shown inFIG.4. The sensor circuit180incorporates a measuring capacitor230, a capacitive proximity sensor235, a bipolar transistor240, a first predefined electrical resistance245, and a second predefined electrical resistance250.

As shown inFIG.4, the first sensor electrode185is electrically connected to a first side260of the measuring capacitor230by a third connection255. The second sensor electrode190is electrically connected to the first side260of the measuring capacitor230by a fourth connection265.

The capacitive proximity sensor235, as shown inFIG.4, comprises a first supply terminal280, a second supply terminal285, a signal terminal290, and a ground terminal295. The capacitive proximity sensor235can, for example, be of the AT42QT1010 type.

A fifth connection275, as shown inFIG.4, electrically connects the first supply terminal280to a second side270of the measuring capacitor230. The signal terminal290is electrically connected to a first side of the first electrical resistor245by a sixth connection300. The second supply terminal285is electrically connected to a first junction310by a seventh connection305. The ground terminal295is electrically connected to the first protective conductor80by an eighth connection315.

In an embodiment, the bipolar transistor240is a NPN-doped bipolar transistor. The bipolar transistor240, as shown inFIG.4, comprises a base320, an emitter325, and a collector330. The first junction310is electrically connected to the signal line85. The first junction310is electrically connected to the collector330by a ninth connection340. The base320is connected to a second side of the first electrical resistance245by a tenth connection345. The emitter325is electrically connected to a first side of the second electrical resistance250by an eleventh connection350. A second side of the second electrical resistance250is electrically connected to the first protective conductor80by a twelfth connection355.

The exemplary monitoring circuit55, as shown inFIG.4, comprises a switching device360, a comparator circuit365, and an energy supply370. The switching device360can be configured, for example, as a relay. The energy supply370delivers a further electrical energy input in relation to ground at a second junction375of the monitoring circuit55, at a supply voltage U. The supply voltage U has a predefined value, for example of 5 V. The second junction375is electrically connected to the comparator circuit365by a thirteenth connection380. The comparator circuit365is electrically connected to the switching device360.

The switching device360has a first circuit state and a second circuit state; the second circuit state is shown inFIG.4. The switching device360is connected to the first electrical conductor70on a first terminal385. On a second terminal390, the switching device360is connected to the second electrical conductor75. A third terminal395of the switching device360is connected to the second vehicle terminal65by the third electrical conductor90. The fourth terminal400is electrically connected to the second vehicle terminal65by the fourth electrical conductor95.

In the second circuit state of the switching device360, shown inFIG.4, the terminals385,390,395,400are mutually electrically isolated. In the first circuit state, the switching device360is closed, and the first terminal385is electrically connected to the third terminal295. In the first circuit state, the second terminal390is electrically connected to the fourth terminal400.

A method of using the charging system10is shown inFIG.5.

In a first process step500, the mains plug45is inserted in the socket outlet110, and the contact element120,125is electrically connected to the socket outlet110. The charging device25can be activated. The switching device360is in the first circuit state. Electrical energy supplied by the AC voltage network is thus transmitted via the mains plug45, the first cable50, the switching device360, the second cable60, the vehicle terminals30,65, and the second connection40to the charging device25. The charging device25controls and/or regulates an electric current and/or an electric voltage of the electrical energy for the charging of the electrical energy accumulator15of the motor vehicle20.

The further electrical energy is transmitted via the signal line85of the first cable50to the first junction310. The further electrical energy is transmitted via the seventh connection305to the second supply terminal285of the proximity sensor235. The proximity sensor235delivers further electrical energy to the first supply terminal280. The further electrical energy is further transmitted via the fifth connection275to the second side270of the measuring capacitor230. The measuring capacitor230is electrically charged by the further electrical energy. By the charging of the measuring capacitor, a first electric field425is generated around the first sensor electrode185, and a second electric field430is generated around the second sensor electrode.

In a second process step505, a user of the charging system10touches the first gripping area155and the second gripping area165with a part of their body, for example the fingers, in order to withdraw the mains plug45from the socket outlet110. As a result, the first electric field425and the second electric field430are altered by the drain of charge from the electric fields425,430to the human body part. As a result, the charging of the measuring capacitor230by the sensor electrode185is also altered.

The proximity sensor235detects the drain of charge of the measuring capacitor230by a change in a capacitor voltage of the measuring capacitor230on the first supply terminal280. On the signal terminal290, the proximity sensor235delivers a signal which is constituted in accordance with the measured capacitor voltage. The signal is transmitted to the base320via the first electrical resistance245, the sixth connection300, and the tenth connection345.

In a third process step510, the bipolar transistor240switches through in response to the signal such that, from the energy supply370, a further current of the further electrical energy flows via the signal line85, the first junction310and the ninth connection340through the bipolar transistor240to the eleventh connection350. The further electrical energy is converted into heat in the second electrical resistance250.

The energy supply370is designed to deliver the further electrical energy at a specific and predefined electric power rating. If the bipolar transistor240is switched through, the (supply) voltage on the second junction375dips in relation to ground. The voltage dip thus correlates to a corresponding through-switching of the bipolar transistor240. If, for example, only one of the two gripping areas155,165is touched, the voltage dip on the second junction375in relation to ground is smaller than in the event that both the gripping areas155,165are touched, and a stronger drain of charge occurs on the measuring capacitor230than in the event that only one of the two gripping areas155,165is touched.

In a fourth process step515, the comparator circuit365detects a voltage on the second junction375, in relation to ground. In the non-switched-through state of the bipolar transistor240, the measured voltage corresponds to the supply voltage U. The comparator circuit365compares the voltage in relation to ground on the second junction375with a predefined threshold value. If the voltage detected on the second junction375is below the predefined threshold value, the comparator circuit365proceeds to the execution of a fifth process step520. If the voltage detected on the second junction375exceeds the predefined threshold value, the comparator circuit365proceeds to the execution of a sixth process step525.

In the fifth process step520, the comparator circuit365switches the switching device360from a first circuit state to a second circuit state, such that the switching device360interrupts the electrical connection between the first terminal385and the third terminal395, and between the second terminal390and the fourth terminal400, and no electrical energy flows via the first and second electrical conductors70,75to the charging device25. Accordingly, the charging process for the charging of the electrical energy accumulator15of the motor vehicle20is interrupted. Switching of the switching device360from the first circuit state to the second circuit state proceeds more rapidly than a typical process for the withdrawal of the mains plug45from the socket outlet110. The generation of an arc between the contact elements120,125to the socket outlet110can be prevented accordingly.

If the measured electric voltage between the second junction375and ground exceeds the predefined threshold value, the comparator circuit365allows the switching device360to remain in the first circuit state, such that electrical energy continues to be transmitted from the first and second electrical conductors70,75to the charging device25, and the charging process for the charging of the electrical energy accumulator15is maintained.

The predefined threshold value is selected such that the predefined threshold value exclusively correlates to a touching of both gripping areas155,165, such that the proximity of the user to the mains plug45, for example by inadvertent contact with only one of the two gripping areas155,165, by means of which no withdrawal of the mains plug45from the socket outlet110is executed, can be distinguished from a withdrawal process in which a human body part touches both of the gripping areas155,165.

A charging system10′ according to another embodiment is shown inFIG.6. The charging system10′ is essentially of identical design to the charging system10shown inFIG.1; like reference numbers refer to like elements. The charging system10′ differs in that the second cable60additionally incorporates a second signal line105. The second signal line105connects the monitoring circuit55to the charging device25, and is designed to transmit a control signal between the monitoring circuit55and the charging device25.

A circuit diagram for the charging system10′ is shown inFIG.7. The charging system10′ is essentially of identical design to the charging system10shown inFIG.4; like reference numbers refer to like elements. The circuit diagram of the charging system10′ differs in that the switching device360is omitted and a transmitter600is provided in place of the switching device360. The transmitter600is connected to the charging device25by the second signal line105. The transmitter600can, for example, deliver a pulse-width-modulated signal to the charging device25. The first and second electrical conductor70,75in the monitoring circuit is permanently connected to the third and fourth electrical conductor90,95.

The operation of the charging system10′ proceeds in a similar manner to that described inFIG.5. The first to fourth process steps500to515are identical to the first to fourth process steps500to515described inFIG.5. A difference is provided in that, in the fifth process step520, the monitoring circuit55, upon the undershoot of the threshold value by the voltage on the second junction375, transmits a first control signal to the charging device25with the transmitter600. The charging device25detects the first control signal, wherein the charging device25, on the basis of the first control signal, interrupts the charging process of the electrical energy accumulator15.

In the sixth process step525, the monitoring circuit55, via the transmitter600, delivers a second control signal to the charging device25with the transmitter600. The charging device25detects the second control signal and, on the basis of the second control signal, the charging device25maintains the execution of the charging process.

In other embodiments, the charging system10can be configured with a different design. It is conceivable that both the sensor unit135and the monitoring circuit55can be configured with a different design. The representation of the monitoring circuit55inFIGS.4and7is merely exemplary; the monitoring circuit55can also be configured as a digital circuit, which evaluates a digital signal which is delivered by the proximity sensor235.