Charging connector for electric and hybrid vehicles

Abstract

The invention relates to a charging connector (1) for electric and hybrid vehicles (5), the charging connector having: a housing (6); charging contacts (2) located in the housing (6), for contacting corresponding charging contacts (7) of a corresponding charging connector (8); and a latent heat storage element (9) which is in thermal contact with at least one charging contact (2). In this way, heat dissipation is improved for a charging connector (1) that is not itself equipped with a cooling system from a charging station (20).

Description

[0001] Charging connectors for electric and hybrid vehicles

[0002] The invention relates to a charging connector for electric and hybrid vehicles, with charging contacts, for contacting corresponding charging contacts of a corresponding charging connector.

[0003] Electric and hybrid vehicles have a rechargeable energy storage device, usually a high-voltage battery, which supplies energy to an electric drive motor during operation. The storage capacity of these high-voltage batteries is limited, so they must be recharged regularly at a charging station. The battery is charged using a charging cable provided between the charging station and the vehicle. The charging cable, for example, in accordance with European standard IEC 62196 Type 2, is equipped with a charging plug on one end that can be plugged into a charging socket provided on the charging station, and with a charging coupling on the other end that can be connected to a charging plug installed in the electric or hybrid vehicle. For the purposes of this article, charging sockets, charging plugs, charging couplings and charging plugs are all referred to as “charging connectors”.Charging sockets and charging couplings have contact sleeves as charging contacts, and charging plugs, as well as charging plugs that can be installed in electric and hybrid vehicles, have contact pins as charging contacts that can be inserted into the contact sleeves. As explained, for example, in EP 3 043 421 A1, a charging current flowing through the charging connector causes it to heat up due to ohmic current heat losses. However, the heating of the charging connector is limited to a threshold temperature increase. For example, according to standard IEC 62196-3, the threshold temperature increase is limited to 50 K. This in turn leads to a maximum charging current, with largely standardized connector geometries, which generally cannot exceed 200 A in continuous load operation.However, with intermittent charging of the battery of an electric or hybrid vehicle, higher charging currents are required over limited periods to charge the battery in the desired short time. This can lead to temporary heating of the charging connectors beyond the limit temperature increase. The cable cross-section of the electrical connector bodies cannot be increased indefinitely, since the connector geometries are standardized and, in addition, the smallest possible amount of conductive material, usually copper, should be used for the electrical connector bodies.

[0004] In this respect, according to EP 3 043 421 A1, the object is to be achieved by providing an electrical connection body which enables increased charging currents with limited heating and therefore has an increased short-time current carrying capacity. This object is to be achieved by providing an electrical connection body for a charging plug or a charging socket, wherein the electrical connection body has a first connection region for the galvanic connection to an electrical energy receiver and a second connection region for the galvanic connection to an electrical energy source, wherein the electrical connection body is designed such that it has a cooling fluid channel formed in the electrical connection body, wherein the cooling fluid channel of the electrical connection body is fluidly connected to a cooling fluid source which is arranged in a charging station.

[0005] Cooling of a charging plug connector for electric and hybrid vehicles, which cooling starts at the side of the charging station, is also well known from the prior art. DE 10 2015 119 338 A1 describes, for example, two connection points for coolant lines being arranged on a contact sleeve element of a charging plug. Coolant is guided in a circle around the contact sleeve element by means of a spiral-shaped plug-in element. The two connection points serve as inlets and outlets for the coolant, which is guided from the charging station to the charging plug. EP 3 433 902 B1 likewise describes a plug connector part with cooled contact elements. Here, too, the supply of coolant via coolant lines to the contact elements of the charging coupling connected to the charging cable is provided on the charging station side.A fluid is provided as the coolant, which is directed perpendicular to the contact element into the hollowed-out contact element and flows back within the contact element. Finally, 10 2016 105 361 B4 also describes a connector part with a cooled contact element, whereby here, too, the charging station side provides for the supply of a coolant via coolant lines to the contact elements of a charging socket connected to the charging cable. Guide elements are arranged on the contact elements to ensure that the coolant, in the form of compressed air, flows around the contact elements.

[0006] Based on this, the object of the present invention is to achieve improved heat dissipation in a charging connector which is not itself equipped with a cooling system on the part of a charging station.

[0007] This object is achieved by the subject matter of the independent claims. Preferred developments of the invention are described in the subclaims.

[0008] According to the invention, a charging connector for electric and hybrid vehicles is thus provided, with charging contacts for contacting corresponding charging contacts of a corresponding charging connector and a latent heat accumulator which is in thermal contact with at least one charging contact.

[0009] Latent heat storage systems are based on the utilization of the enthalpy of thermodynamic changes in state of a storage medium. The principle used here is the utilization of the phase transition from the solid phase to the liquid phase, i.e. the transition from a solidified medium to a molten medium. For this purpose, a latent heat storage system contains a phase change material. Phase change materials are materials that can release or absorb heat or cold during their phase change, depending on their respective melting point and the ambient temperature. The amount of energy stored in the temperature range of the phase change is significantly greater than the energy absorption in a similar temperature interval during heating without a phase transition. During this type of heating without a phase transition, the energy absorption is determined solely by the specific heat capacity of the respective material.Therefore, phase change materials have an advantage in terms of heat storage density, especially at small temperature differences.

[0010] When a phase-change material is heated and its temperature approaches its melting point, the heat absorbed by the phase-change material is used to complete the phase change. Therefore, during the transition from the solid phase to the liquid phase, no temperature increase occurs. Once the phase-change material is completely liquid, the phase-change material continues to heat as before the phase transition.

[0011] Because the phase change material does not heat up any further during the phase transition, the heating is delayed compared to heating without a phase transition. This is exploited according to the invention to keep the temperature at the charging contact, which is in thermally conductive contact with the latent heat storage device, as low as possible. In this way, it is possible to extend the time during a charging process until a critical temperature is reached, at which temperature the charging process must be interrupted until the charging contact has cooled down to a permissible temperature again. The thermal contact in question here between the charging contact and the latent heat storage device can be achieved, for example, by direct physical contact. However, contact via a heat-conducting element is also possible. It is equally possible to arrange the latent heat storage device in the immediate vicinity of the charging contact.

[0012] When we talk about a corresponding charging plug connector in the present case, we mean, on the one hand, a charging plug connector which has the same plug face as the charging plug connector according to the invention, but one plug face has contact pins when the other plug face has contact sleeves, and vice versa. The set comprising the charging plug connector according to the invention and the corresponding charging plug connector can therefore be plugged together. On the other hand, we also talk about a corresponding charging plug connector in the present case when the plug faces in the aforementioned sense only partially correspond, i.e. the corresponding charging plug connector, for example.does not have all the contacts that are present in the charging plug connector according to the invention, but the existing contacts of the corresponding charging plug connector correspond to the charging plug connector according to the invention in terms of the plug face, so that the charging plug connector according to the invention and the corresponding charging plug connector can also be plugged together in this case.

[0013] One such case is a charging connector connected to a charging cable for direct current charging in accordance with the European standard IEC 62196 Type 2. Such a charging connector can be plugged into a charging plug installed in the body of an electric or hybrid vehicle and suitable for both alternating current and direct current charging, whereby the alternating current plug face of the direct current charging connector only contains the communication contacts and the protective contact, but no contacts for the outer conductor and a center conductor for alternating current charging.

[0014] According to a preferred development of the invention, the latent heat accumulator has a container which contains a phase change material whose phase transition from the solid phase to the liquid phase is used to dissipate heat from the charging contact. In this context, it is particularly preferred that the phase change material has a phase transition from the solid phase to the liquid phase within the temperature range between 60 ° C and 80 ° C, preferably between 65 ° C and 75 ° C. Preferably, a material containing paraffin and / or a material containing a salt hydrate is used as the phase change material. Such materials are well known as phase change materials and can be matched to a melting temperature of, for example, 70 ° C.

[0015] In principle, various charging contacts of the charging connector can be cooled by means of the latent heat accumulator. However, it is preferably the case that the charging connector has two direct current charging contacts and the latent heat accumulator is in thermal contact with both direct current charging contacts. In the present case, such contacts are referred to as direct current charging contacts, which are intended exclusively for charging with direct current. With such direct current charging contacts, heating occurs to a particularly high degree when charging with high currents. The use of the invention for direct current contacts is therefore particularly preferred.

[0016] In contrast to direct current contacts, there are alternating current charging contacts. These refer to the outer conductors and the neutral conductor (center conductor), which are also intended for charging with alternating current. An outer conductor (also colloquially referred to as a phase) is a conductor that is live during normal operation and can contribute to the transmission or distribution of electrical energy, but is not a neutral conductor. A neutral conductor is a conductor that is electrically connected to the neutral point and is able to contribute to the distribution of electrical energy. In the European standard IEC 62196 Type 2, the contacts, which are referred to here as alternating current charging contacts, are designated LI, L2 and L3 (outer conductors) and N (neutral conductor), and the direct current charging contacts are designated DC+ and DC-.This understanding should not be contradicted by the fact that the European standard IEC 62196 Type 2 also provides for an operating mode according to which direct current charging takes place via the contacts LI, L2, L3 and N.

[0017] According to a preferred embodiment of the invention, the charging connector has four AC charging contacts, with the latent heat storage device being in thermal contact with all four AC charging contacts. In this way, the advantage of the invention is also available for the AC contacts of the charging connector.

[0018] In principle, the phase change material in the liquid state does not need to be moved within the container. However, according to a preferred development of the invention, a circulation device for circulating the phase change material within the container is arranged in the container. This serves to improve heat conduction in the latent heat storage device after the melting temperature of the phase change material has been exceeded. After the melting temperature of the phase change material has been exceeded, heat circulation via the circulation device can be improved in this way. In this context, it is particularly preferred for the circulation device to have a circulation wheel which interacts with a drive shaft arranged outside the container via a magnetic coupling.

[0019] When the phase change material changes from the solid to the liquid phase, a volume change of typically about 10% occurs. Depending on the arrangement of the container filled with the phase change material relative to the charging contact, the situation may arise that the phase change material melts practically "from bottom to top," creating an excess pressure in the container that cannot be easily compensated due to the solid phase at the top. This problem can be counteracted with the following preferred embodiments of the invention. These preferred embodiments of the invention can also be combined with one another.

[0020] According to a preferred development of the invention, at least one heat-conducting element having a higher thermal conductivity than the phase-change material is arranged in the container. This improves the efficiency of heat introduction into the inner region of the latent heat accumulator. In this context, it is particularly preferred that the heat-conducting element has at least one recess which is closed with an elastic cover element and contains a gas. In this way, a region with a variable volume is integrated into the container.

[0021] Furthermore, according to a preferred development, a plurality of heat-conducting elements are arranged in the container, and spacers are placed between at least some of the heat-conducting elements in order to keep the distances between the heat-conducting elements constant even during the phase transition of the phase-change material. Preferably, metal sheets or plastic ribs are arranged in the container as heat-conducting elements. A plastic optimized for thermal conductivity is preferably used for the plastic ribs.

[0022] Furthermore, according to a preferred development of the invention, the container is provided with a plurality of separate chambers, each of which contains a phase change material. This can be helpful for local pressure equalization. Furthermore, the chambers contain at least two different phase change materials. Different chambers therefore contain different phase change materials. Phase change materials are considered to be different from one another here if they have at least different melting temperatures. It is particularly preferred that a chamber that is closer to the charging contact contains a phase change material whose melting temperature is higher than the melting temperature of a phase change material that is contained in a chamber further away from the charging contact.

[0023] According to a preferred embodiment of the invention, the container has an elastic expansion element and / or an elastic expansion joint. This creates a container that can yield elastically and thus absorb volume changes. For this purpose, elastic plastics, for example, can be used as the material for the container. According to a preferred embodiment of the invention, however, it can also be provided that the container is made entirely of an elastic material.

[0024] Another preferred development of the invention provides for at least one elastically compressible element to be incorporated into the container. This also allows adaptation to an expanding volume within the container. Such an elastically compressible element can be incorporated into the container of the latent heat storage device, for example, as a piece of closed-cell elastomer foam or as an elastic container filled with gas.

[0025] Furthermore, it is preferred that the container of the latent heat storage device is made of an electrically insulating material, such as plastic, or of metal, which has electrical insulation in the area of ​​the charging contact.

[0026] In addition, the housing preferably has two openings that allow filling with the phase-change material. These two openings are preferably sealed in a watertight and pressure-tight manner after filling. The filling quantity is preferably selected such that the volume expansion caused by the phase transition of the phase-change material is compensated by an air cushion, thus reducing the load on the container. The container openings are preferably closed with closure caps using a friction welding process.

[0027] The invention also relates to the use of a previously described charging connector on the vehicle body of an electric or hybrid vehicle.

[0028] The invention is described in more detail below with reference to the drawings using preferred embodiments.

[0029] In the drawings, Fig. 1 shows a charging connector according to a preferred embodiment of the invention in a perspective view from a first side,

[0030] Fig. 2 shows the charging connector from Fig. 1 in a perspective view from a second side,

[0031] Fig. 3 shows a corresponding charging connector in a perspective view,

[0032] Fig. 4 shows the charging connector from Fig. 2 in a not yet closed state in a perspective view,

[0033] Fig. 5a shows the latent heat storage device of the charging connector from Fig. 4 in a perspective view from a first side

[0034] Fig. 5b shows the latent heat storage device of the charging connector from Fig. 4 in a perspective view from a second side,

[0035] Fig. 6a shows the latent heat storage device from Fig. 5a in a plan view,

[0036] Fig. 6b shows the latent heat storage device from Fig. 6a along the section line AA,

[0037] Fig. 6c details of the latent heat storage device from Fig. 6b, Fig. 7a a part of a charging connector according to a preferred embodiment of the invention, in which the latent heat storage device is formed integrally with the housing of the charging connector,

[0038] Fig. 7b shows the part of the charging connector shown in Fig. 7a in a state joined to a second part,

[0039] Fig. 8 schematically shows the arrangement of a circulation device in a latent heat storage device for circulating the phase change material,

[0040] Fig. 9 shows a partial sectional view of a container with several chambers according to a preferred embodiment of the invention and

[0041] Fig. 10 shows the installation of a charging connector according to a preferred embodiment on the body of an electric or hybrid vehicle.

[0042] Fig. 1 shows a charging connector 1 according to a preferred embodiment of the invention in a perspective view from a first side and Fig.

[0043] 2 shows this charging connector 1 in a perspective view from the opposite side. In terms of function and connector face, this is a built-in charging connector for electric and hybrid vehicles according to the European standard IEC 62196 Type 2 with charging contacts 2 arranged in a housing 6, which on the one hand comprise direct current charging contacts 3 and on the other hand also alternating current charging contacts 4. This charging connector 1 is provided here as a built-in charging connector for use on the vehicle body 23 of an electric or hybrid vehicle 5, as can be seen by way of example in Fig. 10.

[0044] A charging connector 8 corresponding to this charging connector 1 is shown in Fig. 3. It is a charging connector according to the European standard IEC 62196 Type 2 with two corresponding charging contacts 7 in the form of two direct current charging contacts. The other contacts shown here, which are not provided with reference symbols, are a protective contact and two communication contacts.

[0045] It is now essential that the charging connector 1 has a latent heat storage device 9 which is in thermal contact with the two direct current charging contacts 3. For this purpose, in Fig. 4, the connecting part 24 of the charging connector 1, which when installed in an electric or hybrid vehicle 5 faces the interior of the electric or hybrid vehicle 5, is shown separately from the plug-in part 25 which is directed outwards. In the installed state of the charging connector 1, electrical lines (not shown here) lead from the connecting part 24 and lead to a battery of the electric or hybrid vehicle 5. The corresponding

[0046] Charging connector 8 plugged in for a charging process.

[0047] As can be seen from Figs. 5a and 5b, the latent heat storage device 9 has a container 10 containing a phase change material (not shown here), whose phase transition from the solid phase to the liquid phase is used to cool the direct current charging contacts 3. The phase change material has been filled into the container 10 via the now closed filling openings 26. The charging contacts 2 are circular in cross-section, and the container 10 has a recess 12 within which the charging contacts 2 are positioned. The function of the latent heat storage device 9 is as follows:

[0048] The phase change material is selected so that it has a melting point of 70°C, meaning it is solid below 70°C and liquid above this temperature. During a normal charging process, in which a direct current flows through the DC charging contacts 3, the phase change material is solid under normal ambient conditions. If the DC charging contacts 3 heat up during the charging process, the phase change material also heats up. This increases its temperature to a temperature value of 70°C while remaining in the solid phase. From the melting point of 70°C, the phase change material begins to melt, i.e., to liquefy. During this melting process, the temperature of the phase change material does not increase. Rather, its temperature remains at 70°C. Only when the phase change material is completely melted, i.e., has been converted into its liquid phase, does a further temperature increase occur.

[0049] This has the positive effect of delaying the heating of the phase-change material, namely by the time it takes for the phase-change material to completely melt. In this way, heat can be absorbed very effectively by the DC charging contacts 3, enabling extended operation of the DC charging process without exceeding a critical temperature of the charging connector 1. After the charging process has ended, the phase-change material cools down again by releasing its heat into its surroundings and then solidifies again.

[0050] 6a to 6c, heat-conducting elements 14 in the form of metal sheets are arranged in the container 10, said metal sheets having a higher thermal conductivity than the phase change material 11. As can be seen from Fig. 6b, these heat-conducting elements 14 run in planes that are perpendicular to the longitudinal axes of the direct current charging contacts 3. This facilitates the introduction of heat from the direct current charging contacts 3 into the phase change material. From Fig. 6c, which shows the area marked by a dashed rectangle in Fig. 6b in an enlarged view, it can be seen that spacers 18 are placed between the heat-conducting elements 14. These serve to keep the distances between the heat-conducting elements 14 constant even during the phase transition of the phase change material 11. Unlike the latent heat storage 9 shown in Figs. 5a and 5b, the one shown in Figs.7a and 7b, the charging connector 1 is designed such that the container 10 is not a separate component from the housing 6 of the charging connector 1, which is inserted into the housing 6. Rather, the latent heat storage device 9 is designed integrally with the housing 6 of the charging connector 1. This can have manufacturing advantages.

[0051] From Fig. 8, it can be seen that a circulation device 13 for circulating the phase-change material is arranged in the container 10. This circulation device can improve the heat distribution in the container 10 after the melting temperature of the phase-change material has been exceeded. The circulation device 13 has a circulation wheel 17 provided with a magnetic ring 16. This magnetic ring 16 interacts with a magnetic wheel 21 arranged outside the container 10, which is located at the end of a drive shaft 28 of an electric motor 22. In this way, a magnetic coupling is realized, so that the circulation wheel 17 can be driven by the electric motor 22 arranged outside the container 10.

[0052] Fig. 9 shows a container 10 according to a preferred embodiment, in a section in a sectional view. The area of ​​the container 10 around the area of ​​the direct current charging contact 3 is shown. It can also be seen from Fig. 10 that the container 10 has a plurality of separate chambers 31, 32 which are filled with different phase change materials 29, 30. The chamber 31 which is arranged around the direct current charging contact 3 and thus closer to the charging contact is filled with a phase change material 29 whose melting temperature is higher than the melting temperature of the phase change material 30 which is located in the two other chambers 32 which are both further away from the direct current charging contact 3.

[0053] Reference symbol list

[0054] 1 charging connector

[0055] 2 charging contacts

[0056] 3 DC charging contacts

[0057] 4 AC charging contacts

[0058] 5 Electric or hybrid vehicle

[0059] 6 housings

[0060] 7 corresponding charging contacts

[0061] 8 corresponding charging connector

[0062] 9 Latent heat storage

[0063] 10 containers

[0064] 11 Phase change material

[0065] 12 Recess

[0066] 13 Circulation device

[0067] 14 Heat conducting element

[0068] 15 Recess

[0069] 16 magnetic ring

[0070] 17 Circulation wheel

[0071] 18 spacers

[0072] 21 Magnetic wheel

[0073] 22 electric motor

[0074] 23 Vehicle body

[0075] 24 connecting part

[0076] 25 plug-in part

[0077] 26 filling openings

[0078] 27 Longitudinal axes of the DC charging contacts

[0079] 28 Drive shaft

[0080] 29 first phase change material

[0081] 30 second phase change material

[0082] 31 near chamber 32 more distant chambers

Claims

Patent claims 1. Charging connector (1) for electric and hybrid vehicles (5), with a housing (6), charging contacts (2) arranged in the housing (6), for contacting corresponding charging contacts (7) of a corresponding charging connector (8) and a latent heat accumulator (9) which is in thermal contact with at least one charging contact (2).

2. Charging connector (1) according to claim 1, wherein the latent heat storage device (9) has a container (10) containing a phase change material (11) whose phase transition from the solid phase to the liquid phase can be used to cool the charging contact (2).

3. Charging connector (1) according to claim 2, wherein the charging contact (2) in thermal contact with the latent heat storage device (9) is circular in cross-section and the container (10) has a recess (12) within which the charging contact (2) is positioned.

4. Charging connector (1) according to one of claims 2 or 3, wherein the container (10) is designed integrally with the housing (6) of the charging connector (1).

5. Charging connector (1) according to one of claims 2 to 4, wherein a circulation device (13) for circulating the phase change material (11) within the container (10) is arranged in the container (10).

6. Charging connector (1) according to one of claims 2 to 5, wherein at least one heat-conducting element (14) is arranged in the container (10), which has a higher thermal conductivity than the phase change material (11).

7. Charging connector (1) according to claim 5 or 6, wherein a plurality of heat conducting elements (14) are arranged in the container and spacers (18) are placed between at least some of the heat conducting elements (14) in order to keep the distances between the heat conducting elements (14) constant even during the phase transition of the phase change material (11).

8. Charging connector (1) according to one of claims 2 to 7, wherein a plurality of separate chambers (19) are arranged in the container, each of which contains a phase change material (11).

9. Charging connector (1) according to claim 8, wherein at least two chambers (19) are filled with different phase change materials.

10. Charging connector (1) according to claim 9, wherein a chamber (19) located closer to the charging contact (2) contains a phase change material (11) whose melting temperature is higher than the melting temperature of a phase change material (11) contained in a chamber (19) further away from the charging contact.

11. Use of a charging connector (1) according to one of the preceding claims on the vehicle body (23) of an electric or hybrid vehicle (5).

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