Liquid-cooled charging plug

Abstract

The invention relates to a liquid-cooled charging plug with at least two contact elements for a detachable, electrically conductive connection of a battery-electric vehicle to a charging station, comprising a charging plug housing for enclosing the at least two contact elements, wherein a separate inlet nozzle is arranged in a central area between the at least two contact elements, which supports a symmetrical inflow of coolant, wherein a temperature sensor of the charging plug is arranged at the end face of the inlet nozzle and the temperature sensor is at least partially helical and has a threaded shaft that is screwed into an end face threaded bore of the inlet nozzle.

Description

The invention relates to a liquid-cooled charging plug having at least two contact elements for the detachable, electrically conductive connection of a battery-electric vehicle to a charging station, having a charging plug housing for enclosing the at least two contact elements.From the documents WO 2024 / 037232 A1, CN 107681314 A and CN 115347394 A generic, liquid-cooled charging plugs are known, in which a connection piece is provided for supplying coolant.The document CN 217134729 U concerns the sensory temperature monitoring of a plug connector on a coolant channel.Contacts generally have at least one electrically conductive contact section for releasable, temporary or plug-in connection with a corresponding mating contact element and a shank section adjoining the contact section for fastening an electrical line to the contact. Such a contact, plug contact, high-current contact can be used on a charging plug or a charging socket, for example for charging an electrically driven vehicle. In this case, a cable is connected on the one hand to a charging station and on the other hand carries a plug connector part in the form of a charging plug which can be inserted into an associated mating plug connector part in the form of a charging socket on a vehicle, in order in this way to establish an electrical connection between the charging station and the vehicle.During a charging process of electrical energy stores, accumulators, heat arises as a result of the high transmitted electrical powers, electrical currents not only on the cable to which a charging plug is connected, for example, to a charging station, but also on the charging plug and in particular within the charging plug, for example, on high-current contacts via which an electrical contact with associated mating contacts is produced, for example, on the side of a charging socket on an electric vehicle, when the charging plug is inserted into the charging socket and the electrical power is transmitted.Supply and charging currents can in principle be transmitted as direct currents or as alternating currents, wherein in particular charging currents and high-current ranges in the form of direct current have a large current intensity, for example greater than 200 A or even greater than 300 A or even 350 A, and can lead to heating of the cable just as of a high-current contact connected to the cable.In order to be able to charge trucks driven by battery electricity quickly and efficiently, even higher electrical charging powers are generally required. A so-called megawatt charging system standard (abbreviation MCS) is intended to be used as a rapid charging system in the future and is intended to allow a charging power of up to 3.75 megawatts, wherein the voltage may have up to 1,250 V and the charging current may have up to 3,000 A.Regardless of the specification of the charging plug or charging plug socket (for example according to the IEC 62196-2 or IEC 62196-3 standard or CHAdeMO standard or according to the Megawatt Charging System standard), it is very particularly important, especially at higher and high charging powers, that charging plugs and / or charging plug sockets are very carefully and reliably sealed.High-current contacts for charging plugs which are manufactured from an electrically conductive material, for example from a copper material, heat up when a charging current flows via the contacts, plug contacts, high-current contacts, wherein in principle the contacts are to be dimensioned as a function of the charging current to be transmitted in such a way that the contacts have a sufficient current-carrying capacity and heating at the contact elements is limited. In this case, the greater the charging current to be transmitted, the greater the size of a contact. Scaling of the contact element size with increasing charging current is, however, subject to limits due to the associated installation space requirement, weight and costs. There is therefore a need to transmit a large charging current with a comparatively small-sized contact.Within the scope of the desired electromobility, high charging currents are of particular importance. Only in this way can electric vehicles or their energy stores be "refueling" in a short time.One solution approach fundamentally known in the prior art is to cool contacts, high-current contacts passively or actively in order to realize the transmission of the electrical power with limited heating of the power-transmitting components even in the case of components of smaller dimensions.This basic relationship in connection with electrically releasable contacting of electrically driven vehicles with a charging station is shown in DE 10 2018 112 746 A1. The present invention provides a charging station for an electric vehicle having a base, a plug with plug contacts for plugging in on a compatible socket on the electric vehicle, and a bendable cable which is fastened to the base by a first end and is fastened to the plug by a second end of the cable opposite the first. The plug is movable back and forth between a parking position and a charging position. The plug contacts of the plug point in the same spatial direction in the parking position and in the charging position. The cable and / or the plug have an internal cooling system operatively connected to the base, which is supplied with a cooling medium from the base. The cooling system comprises at least one internal cooling circuit.When cooling such charging plugs and charging cables, it is a particular challenge to design the cooling performance as effectively as possible and to maximize the cooling performance that can be achieved. It is also interesting to control the cooling capacity as required and to adapt it to the respective heating situation.In order to realize the supply of a fluid cooling medium into the charging plug and to the components to be cooled within the charging plug, various structural concepts are known. Frequently, a cooling fluid supply is provided with separate cooling fluid lines which, in addition to the power lines, are designed as additional components. Another solution is to provide an integrative construction of power lines and cooling fluid hoses.An integrative cooling concept approach is shown, for example, in WO 2017 / 133893 A1. A cable arrangement is presented comprising a cable with a cable hose and an arranged conductor. The cable hose is arranged at a distance from the conductor and forms a first intermediate space between the at least conductor and the cable hose. At least one tube for conveying a cooling fluid and a connector comprising at least one contact element connected to the at least one conductor and a chamber. The chamber includes a first port connected to the first monitoring space between the at least one conductor and the cable hose and a second port connected to the at least one pipe.Disadvantages of the solutions offered in the prior art are the frequently very complicated and angled flow channels of the cooling fluid within the charging plug. This often causes a deterioration in the cooling performance and entails very complicated injection molding tools for the charging plug housings and charging plug inserts, since charging plug housings and charging plug inserts are frequently produced by plastic injection molding processes. With regard to the influencing of cooling capacities, solutions are found in the prior art which are based only on the variation of the cooling fluid volume flow.It is the object of the invention to further develop existing liquid-cooled charging plugs, so that the aforementioned disadvantages of the prior art are at least partially reduced and the effectiveness of the cooling performance is improved.To achieve the object, the invention proposes a liquid-cooled charging plug having the features of patent claim 1. In this case, provision is made for a separate coolant inflow, independent of the power lines, to be provided through a tubular supply line, which introduces coolant into the charging plug via an inflow connection piece into a region between the at least two contact elements. Separately in this context means that the separate coolant inflow of the inflow connection piece takes place by means of an inflow line separate from the power lines.The invention recognizes that a coolant inflow arranged in the central region and between the at least two contact elements of the charging plug is suitable for implementing a largely symmetrical inflow of coolant and for converting the supplied coolant volume flow into at least two partial coolant volume flows in a geometrically simple manner. Symmetrical inflow means that the partial coolant volume flows to the contact elements travel an approximately equal distance starting from the supplied coolant volume flow. If the charging plug is constructed on the inside by an insert with contact elements, the coolant is supplied in the central region of the insert.The largely symmetrical inflow of coolant and the simple coolant volume flow guidance make it possible to construct the charging plug and / or the insert part in a constructionally geometrically simple manner, so that these parts, which are preferably produced by plastic injection molding, can be produced without undercuts and thus by means of simple injection molding tools.Within the supplied coolant volume flow, the invention provides for the arrangement of a temperature sensor. It is thus possible to measure the inlet temperature of the coolant before the heat exchange with the contact elements. Furthermore, the invention provides for the temperature sensor to be designed geometrically like a screw and for the sensor element to be placed at the end face at the end of the threaded section. This construction supports the simple construction of the insert part or charging plug and makes it possible to use this integrative temperature sensor screw both as a temperature sensor and as a releasable fastening means.With knowledge of the inlet coolant temperature and a downstream measurement of the coolant temperature after the heat exchange with the contact elements, it is possible to draw conclusions about the temperature of the contact elements and, in addition, to adapt the cooling capacity at a constant coolant volume flow by the targeted lowering of the coolant inlet temperature.The invention is particularly advantageous in the case of high-voltage charging plugs such as, for example, MCS charging plugs having DC contact elements (DC=breviate of direct current, direct current), because the required cooling power can become particularly high here.The invention is explained in more detail below with reference to an exemplary embodiment in conjunction with the figures. The following are shown: FIG. 1 shows a sectional side view of an insert with an inflow connection piece and a plastic cover; FIG. 2 is a sectional side view of the inflow connection piece with plastic cover.FIG. 1 shows a sectional side view of an insert 1 for a liquid-cooled charging plug with inflow connection piece 2 and plastic cover 7. Alternatively, a liquid-cooled charging plug without an insert can also be provided, in the case of the charging plug housing of which the insert components are an integrative component.The inflow connector 2 is introduced in the side of the insert part 1 facing away from the plug-in direction SR and has a tubular basic geometry for conducting the supplied coolant volume flow ZK. The plastic cover 7 is introduced in the side of the insert part 1 facing the plug-in direction SR and has a pot-shaped basic geometry with a collar. The plug-in direction SR in this context denotes the plug-in direction of the charging plug for the detachable plugging together of charging plug and charging plug socket.The plastic cover 7 can have a concentric, annular recess on the end face, in which the inflow connector 2 engages. Alternatively, the front recess of the plastic cover 7 can be formed by a key-shaped recess, in which a correspondingly formed end-side section of the inflow connector 2 engages and thus a rotation prevention is provided. Alternatively or additionally, a rotation prevention can be effected by a key surface combination between the inflow connection piece 2 and the insert part 1.The inflow connection piece 2 and plastic cover 7 folded together at the end in this way are detachably fastened to one another by a helical temperature sensor 10, which projects through a bore in the pot base of the plastic cover 7 and is screwed with its external thread into an internal threaded bore at the end of the inflow connection piece 2. The sensing part of the temperature sensor 10 is arranged at the end of the threaded shank of the helical temperature sensor 10 and protrudes at least in regions into the supplied coolant volume flow ZK. This arrangement is particularly advantageous in two respects.The integrative design of the temperature sensor 10 as a sensor element and as a fastening means reduces the diversity of parts. At the same time, the positioning of the temperature sensor 10 with its screw shank tip into the supplied coolant volume flow ZK is particularly advantageous because the inlet temperature of the coolant is thereby measured.FIG. 2 shows a sectional side view of the inflow connection piece 2 with plastic cover 7. the inflow connection piece 2 and the plastic cover 7 are put together at their respective end sides and are detachably fastened to one another by the temperature sensor 10, which is formed in an integral manner geometrically as a fastening screw with a screw head and threaded shaft. Since thread pairings cannot seal, the sealing function between the inflow cross section 5 and the plastic cover 7 is ensured by a sealing disk 8 placed under the screw head of the temperature sensor 10.The sealing function required between the insert part 1 and the inflow connection piece 2 is provided by at least one O-ring seal. For this purpose, at least one inflow connection groove 4 is introduced into the outer contour of the inflow connection piece, into which groove an O-ring can be inserted. In this exemplary embodiment, two inflow connection grooves 4 are worked in, so that the sealing safety is increased. The plastic cover 7 also contains the sealing function with respect to the insert part by an O-ring seal. For this purpose, the plastic cover 7 has a circumferential plastic cover groove 9 introduced on the outside, into which an O-ring can be inserted.The inflow connector 2 has a coolant hose connection 3, so that a hose-shaped coolant inflow line can be connected and a coolant volume flow can be introduced into the inflow connector 2. Inside the inflow connection piece 2, the supplied coolant volume flow ZK is conducted in the inflow cross section 5. The axial extension of the inflow cross section 5 is, starting from the coolant hose connection 3, into the opposite end-side region of the inflow connector 2, in which both the temperature sensor 10 is arranged and at least two transverse bores 6 are introduced. As a result, the temperature sensor 10 is surrounded by the supplied coolant volume flow ZK in the end-side region. In addition, as a result of the at least two transverse bores 6, deflection of the supplied coolant volume flow ZK into at least two partial coolant volume flows TK is formed. In the exemplary embodiment shown in FIG. 2, three transverse bores 6 are provided, so that three partial coolant volume flows TK are formed.While the supplied coolant volume flow ZK flows largely in a laminar manner in the region of the inflow cross section 5, a predominantly turbulent flow will form in the region of the transverse bore 6 and of the temperature sensor 10 as a result of the deflection of the supplied coolant volume flow ZK. This has the consequence that the temperature determination by the temperature sensor 10 in exactly this region senses the inflow temperature of the coolant particularly exactly.The inflow connection 2 is preferably produced on the basis of a metal material. Metal materials have good thermal conductivity and material strength, so that they have advantageous properties for the inflow connector 2. The structural design of the inflow connector 2 and the plastic cover 7 makes it possible for the insert part 1 and / or the charging plug housing to be able to be produced very easily in terms of injection molding and largely without undercuts and to be able to be easily removed from the injection molding tool.List of reference characters1 Insert part 2 Inflow connection piece 3 Coolant hose connection 4 Inflow connection piece groove 5 Inflow cross section 6 Transverse bore 7 Plastic cover 8 Sealing disk 9 Plastic cover groove 10 Temperature sensor SR Plug-in direction TK Partial coolant volume flow ZK Supplied coolant volume flow

Claims

Liquid-cooled charging plug having at least two contact elements for the detachable, electrically conductive connection of a battery-electric vehicle to a charging station, having a charging plug housing for enclosing the at least two contact elements, wherein a separate inflow connection piece (2) is arranged in a central region between the at least two contact elements, said inflow connection piece supporting a symmetrical inflow of coolant, characterized in that a temperature sensor (10) of the charging plug is arranged on the end face of the inflow connection piece (2), and the temperature sensor (10) is helical at least in sections and has a threaded shank which is screwed into an end face threaded bore of the inflow connection piece (2).Liquid-cooled charging plug according to Claim 1, characterized in that the inflow connection piece (2) has an inflow cross section (5) for conducting a supplied coolant volume flow (ZK).Liquid-cooled charging plug according to Claim 1, characterized in that the inflow connection piece (2) has a coolant hose connection (3) for coupling a separate coolant hose.Liquid-cooled charging plug according to Claim 2, characterized in that the inflow connection piece (2) has at least two transverse bores (6), with the result that the coolant volume flow (ZK) supplied is deflected into at least two partial coolant volume flows (TK).Liquid-cooled charging plug according to Claim 1, characterized in that at least one inflow connection groove (4) is introduced into the outer contour of the inflow connection piece (2).Liquid-cooled charging plug according to Claim 1, characterized in that the temperature sensor (10) has, on the end of its threaded shank, a device for temperature sensing.Liquid-cooled charging plug according to Claim 1, characterized in that a plastic cover (7) of the charging plug is arranged axially flush with the inflow connection piece (2), in front of the inflow connection piece (2) in the plug-in direction (SR) and on the end face of the inflow connection piece (2).Liquid-cooled charging plug according to Claim 7, characterized in that the plastic cover (7) has a circumferential plastic cover groove (9) introduced on the outside.Liquid-cooled charging plug according to Claim 7, characterized in that the inflow connection piece (2) is folded at its end face with the plastic cover (7) and is detachably fastened by the helical temperature sensor (10).Liquid-cooled charging plug according to Claim 9, characterized in that a sealing disc (8) of the charging plug is arranged below a screw head of the temperature sensor (10).Liquid-cooled charging plug according to one of the preceding claims, characterized in that the liquid-cooled charging plug is an MCS charging plug with DC contact elements.

Images