Power coupling device comprising a power jack for detachably connecting with a power plug, and such a power jack and an associated power plug

Abstract

The present invention relates to a power jack (1) for detachably connecting to a power plug (30), the power jack (1) having a body (2) made of an electrically conductive material with a hole (2') for accommodating a substantially cylindrical pin (31) of the power plug (30) and with a device (4) for connecting to a power cable (40), the base body (2) having a helical groove (5) for receiving a locking nose (32) of the power plug (30), the base body (2) of the power jack (1) including a bushing (3) with the helical groove (5) and a receptacle (3') for the bushing (3), as well as a power coupling (50) for such a power jack (1) and an associated power plug (30). In the present invention, the spiral groove (5) includes at least two regions (a, c) with a positive slope and regions (b, d) with a negative slope, the regions (b, d) with a negative slope being located at the end of each region (a, c) with a positive slope to form a respective latching step, the receptacle (3') is formed from a metal or metal alloy with a sheath (13) of an electrically insulating material, and the bushing (3) is formed from a material harder than the receptacle (3').

Description

[Technical Field]

[0001] The present invention relates to a power coupling (50) including a power jack and an associated power plug having substantially cylindrical pins (31), wherein the power jack is formed for detachable connection to the power plug and comprises a base body made of a conductive material having holes for accommodating the substantially cylindrical pins of the power plug, and a device for connecting to a power cable, the base body having a spiral groove disposed therein for receiving a locking nose of the power plug, the base body including a bushing having the spiral groove and a receptacle for the bushing.

[0002] The term "substantially cylindrical" is intended to clarify that the holes in the base body of the power jack and the pins of the matching power plug may also deviate slightly from rotational symmetry, for example, and may be slightly eccentric. [Background technology]

[0003] This type of power jack, in combination with an appropriate power plug, serves as a power coupling for transmitting high currents of several hundred amperes. For example, such power couplings are used in welding systems, transmitting high currents from a welding power source to a welding torch and the workpiece. Such connections are common in welding technology and are covered by the standard DIN EN 60974-12 "Plug connections for welding cables." However, such power jacks can also be used in other applications, such as photovoltaic systems or battery chargers, as part of corresponding power couplings for transmitting direct current from photovoltaic modules or charging current for batteries.

[0004] In welding systems, DINSE Ges.mbH plugs are often used to connect power cables or hose packages. These are known to welding engineers as DINSE® plugs, DINSE® jacks, or DINSE® connectors. In a DINSE® connector, a plug with a locking nose is screwed into a jack with a helical groove through a rotation angle of approximately 270°, with a taper of approximately 4 mm per 360°. The thread-like interaction between the plug and the jack creates a preload or tightening torque for the connection, or an axial force that keeps the plug connection connected. Depending on the current, the plug and jack have different cross-sectional areas.

[0005] In shielding gas and plasma welding systems, the shielding gas or plasma compatible medium is also supplied through a corresponding channel in the center of the power coupling.

[0006] The relatively steep spiral groove in prior art power jacks, combined with the short preload length (the length of the plug connection extending from the current contact surface between the power plug and the power jack to the latching nose of the power plug) and the high preload surface (the surface of the power jack or the cross section of the power plug pin where the force is applied) results in a very steep preload characteristic, i.e., a large gradient in the force-displacement curve of the plug connection. This results in a very small energy required to release the connection, i.e., to pull the plug from the jack, and the connection may be unintentionally released even due to temperature changes or vibration. Once the connection loses its preload force, the contact resistance of the power coupling increases rapidly. High currents can cause local overheating at the connection between the power jack and the power plug, potentially oxidizing parts of the power cable or the power coupling. Oxidation of the power coupling increases the operating temperature, potentially damaging the power plug or plastic parts of the power jack, the connected power cable, and connected equipment (such as a welding power supply). If the specified temperature values are significantly exceeded, injuries to workers cannot be ruled out. Furthermore, an increase in contact resistance of the power coupling can adversely affect processes such as welding, potentially resulting in the production of defective products.

[0007] Power jacks have been further developed to improve the contact resistance of power couplings by significantly increasing the connection release energy or torque through the use of spring-loaded locking noses on the plug. Such power couplings are described, for example, in WO 2016 / 128557 A1, in which the power coupling's power plug includes a displaceably mounted locking pin that is held in a default position by a spring device. Disadvantages of this plug include a complex structure, high manufacturing costs, and the central structure of the power plug, which does not or cannot easily implement an axial hole or cavity for gas guidance. Finally, the complexity of the solution is also disadvantageous because the power plug is typically exposed to more severe environmental conditions than the jack and is also located in a price-sensitive part of the power coupling.

[0008] DE 10 2018 007 686 A1 describes a welding power cable for connection to a welding power source, in which a bayonet element with a bayonet locking mechanism reduces the risk of unintentional separation of the power plug from the power jack due to twisting.

[0009] FR 2 270 695 A1 discloses a power jack of the type in question, the base body of which consists of a spirally grooved bushing and a receptacle for said bushing. Summary of the Invention

[0010] The object of the present invention is to provide a power jack as described above for coupling to transmit high currents of up to several hundred amperes, such as may occur in welding systems, photovoltaic systems, or battery chargers, thereby ensuring the lowest possible contact resistance and thus enabling optimal current transmission while preventing or at least minimizing the risk of local overheating of the power jack and power plug due to unacceptably high current densities. The power jack should be as simple and cost-effective as possible to manufacture and should allow for the introduction of shielding gas or the like in the center. The disadvantages of known power jacks should be avoided or reduced.

[0011] The objective of the present invention is achieved by the power coupling described above, in which the spiral groove of the power jack base body comprises at least two positively sloped regions and two negatively sloped regions located at the ends of each positively sloped region, forming respective latching steps; the receptacle is formed from a metal or metal alloy with a sheath of electrically insulating material; and the bushing is formed from a material harder than the receptacle and harder than the cylindrical pin of the power plug. Separating the base body into at least two parts, i.e., a spirally sloped bushing and a bushing receptacle, allows the components to be manufactured from different materials, and further provides the following advantages. Providing at least two positively sloped regions in the power jack bushing and negatively sloped regions at the ends of each positively sloped region allows tactile feedback to be provided to the operator when each latching step is reached. Furthermore, this allows a release torque higher than the tightening torque, preventing the power coupling from being easily released unintentionally. Providing at least two latching steps allows the power plug to be reliably locked to the power jack by selecting the second or subsequent latching step, even if the power plug is worn. That is, after reaching the first latching step, the power plug can be twisted further into the power jack and securely held in place by the next latching step or the one after that. Better power coupling connection results also reduce contact resistance, reducing the risk of damage or deterioration to the power jack, power plug, power cable, or connected devices, as well as the risk of injury due to overheating and adverse effects on processes such as welding. The measures taken in the power jack allow connection of conventional power plugs, such as the aforementioned DINSE® plug, without the need to replace conventional components, such as welding component plugs. Another advantage of this power jack is that no structural measures are required around the central axis of the power jack, making it easy to provide holes or cavities in the center of the power jack for guiding, for example, shielding gas, plasma generation media, or welding wire.The fact that the technical features for solving the problem according to the present invention are located in the power jack means that the costs required for this can be shifted from the power plug, which is a cost-sensitive part of the power coupling, to the power jack. Furthermore, the power jack is usually located in the respective device, e.g., a welding power supply, and is less exposed to harsh environmental conditions than the power plug. However, the design measures required for the power jack are also relatively simple and can be implemented cost-effectively.

[0012] When a spring element is arranged in the receptacle so as to spring-support the bushing of the base body of the power jack in the axial direction of the receptacle, and when the spring element is preferably formed by at least one wire spring washer, particularly preferably two wire spring washers with a spacer ring arranged between the wire spring washers, the connection between the power jack and the power plug is further improved and the contact resistance of the power coupling is reduced. The spring force allows for a higher release torque compared to the tightening torque of the plug connection, further reducing the risk of accidental disconnection of the power plug from the power jack. The plug connection is prevented from loosening due to thermal cycling, vibration, or impact. By selecting an appropriate spring element, the connection force of the power connection, and therefore the connection resistance, can be adjusted. The spring element can be used to adjust the force acting on the connection surface at each latching step. The force acting on the connection surface is 5 to 50 N / mm. 2 It is preferable that:

[0013] Preferably, the spring element is formed by at least one wire spring washer, which can be manufactured very cost-effectively using wavy flat wire and can be positioned within the power jack in a particularly space-saving manner, without requiring a central area of the power jack that can be used to guide shielding gas, etc.

[0014] Particularly preferably, the spring element is formed by two wire spring washers and a spacer ring arranged between the wire spring washers, which prevents the twisting of the wire springs of the spring washers on either side of the spacer ring from reducing the spring travel of the spring washers, thereby ensuring the full spring force of the spring washers.

[0015] The power jack bushing is formed from a material that is harder than the receptacle and harder than the cylindrical pins of the power plug, so that wear preferably occurs on the softer power plug and not on the harder power jack bushing.

[0016] Ideally, the bushing of the power jack base body would include positioning features, particularly axial latching noses, to prevent twisting of the base body relative to the receptacle. Providing such positioning features on the bushing is easy and does not significantly increase manufacturing costs.

[0017] The power jack base body receptacle can be comprised of two connectable parts, and the two parts of the base body receptacle are connectable to each other, preferably by press-fit. This means that the power jack can be assembled very quickly and easily by simply placing the necessary parts, such as bushings and any spring elements, in place on the power jack body receptacle parts and connecting the parts together. Preferably, the two parts of the base body receptacle can be connected to each other by press-fit. Alternatively, the parts of the base body receptacle can be detachably connected to each other, for example, by a left-handed or right-handed screw joint.

[0018] In particular, the receptacle of the base body of the power jack may be made of steel or a steel alloy, or brass or a brass alloy.

[0019] The bushing of the power jack is preferably made of steel or a steel alloy, which has the advantage that wear occurs on the softer power plug and not on the harder bushing of the power jack.

[0020] The receptacle of the base body includes a flat front surface for contact to ensure optimal current transmission to the power plug. The flat design of the receptacle's front surface allows for uniformly low contact resistance across the entire contact surface. Localized overheating can occur on contact surfaces with high contact resistance, especially at high current densities, but this can be prevented. In cases where shielding gas or the like passes through the power jack, it is preferable for the periphery of the central axis to be recessed and the front surface to be annular.

[0021] To improve current transfer, the front surface of the receptacle on the base body can be coated, for example with silver. Zinc or gold coatings are also possible for low contact resistance. Phosphate coatings, possibly in combination with other chemicals, protect the contact surfaces from corrosion.

[0022] According to a feature of the present invention, the groove of the bushing of the base body of the power jack extends through a rotation angle of 90° to 270°, which is suitable for processing the power coupling.

[0023] The slope of the positively sloped region of the groove in the bushing of the power jack base body is ideally between 1 mm and 8 mm per 360°. These values are suitable for proper connection of the power jack with a suitable power plug with a locking nose. The slope of the positively sloped spiral groove region does not necessarily have to be constant; for example, it may have an increasing or decreasing slope.

[0024] The gradient of the groove region in the bushing of the negative gradient power jack base body to form the latching step is between 0.1 mm and 20 mm per 360°, preferably between 1 mm and 20 mm, and particularly preferably between 5 mm and 20 mm. The provision of the negative gradient region can further increase the release torque compared to the tightening torque and improve the tactile feedback to the user when the latching step is reached. As described above for the positive gradient region, the gradient of the spiral groove region in the negative gradient bushing can also be implemented in stages.

[0025] According to a further feature of the present invention, the spiral groove in the bushing of the base body of the power jack may include a region of negative slope followed by a region of no slope or no significant slope. By providing a slope between the region of negative slope and the region of no slope, a smooth transition between these regions of the spiral groove can be achieved. Such a transition may have a positive effect on the tactile perception of a user.

[0026] In the simplest case, the device for connecting to the power cable can be formed by a screw joint, which allows the connection between the power cable and the power jack to be realized easily and at low cost.

[0027] If the receptacle of the main body of the power jack includes an axial through-hole or the like for guiding a shielding gas or a plasma compatible medium, the shielding gas or the plasma compatible medium can be guided through the power current contact. Instead of a rotationally symmetrical hole, a cavity of a different shape can also be provided in the axial direction in the receptacle of the base body for guiding a shielding gas or the like. [Brief explanation of the drawings]

[0028] The invention will now be described in more detail with reference to the accompanying drawings, in which:

[0029] [Figure 1] 1 illustrates a conventional power coupling consisting of a power jack and a power plug in a disconnected state. [Figure 2] 2 is a cross-sectional view of the prior art power coupling according to FIG. 1 showing the connected power plug and power jack. FIG. [Figure 3] 1 is an exploded perspective view of a power jack according to the present invention; [Figure 4A] FIG. 10 is a detailed view of a bushing of an embodiment of a power jack. [Figure 4B] FIG. 10 is a detailed view of a bushing of an embodiment of a power jack. [Figure 4C] FIG. 10 is a detailed view of a bushing of an embodiment of a power jack. [Figure 4D] FIG. 10 is a detailed view of a bushing of an embodiment of a power jack. [Figure 5] FIG. 2 is a cross-sectional view of the power jack. [Figure 6] 1 is a cross-sectional view of a power coupling in which the power plug has not yet latched onto the power jack. FIG. [Figure 7] 7 is a cross-sectional view of the power coupling portion shown in FIG. 6, with the power plug latched to the power jack. [Figure 8] 1 is a force-displacement preload diagram of a power coupling with a power jack in accordance with the present invention compared to a power coupling with a conventional power jack; FIG. [Figure 9] 4 shows the contact resistance and power loss of a power coupling with a power jack according to the present invention compared to a power coupling with a conventional plug connection. DETAILED DESCRIPTION OF THE INVENTION

[0030] In FIG. 1, a power coupling 50 consisting of a power jack 1 and a power plug 30 according to the prior art is shown in an unconnected state. In addition to a base body, corresponding insulators, and a device for connecting to a power cable 40, which are not described in detail, the power plug 30 includes a substantially cylindrical pin 31 made of an electrically conductive material with a locking nose 32. The power jack 1 for detachably connecting to the power plug 30 includes a base body 2 made of an electrically conductive material having a hole 2' for accommodating the pin 31 of the power plug 30. The power jack 1 includes a device for connecting to the power cable 40, such as a screw joint, which is not described in detail (see FIG. 2). The base body 2 of the power jack 1 is provided with a spiral groove 5 for receiving the locking nose 32 of the power plug 30. To connect the power plug 30 to the power jack 1, the substantially cylindrical pin 31 of the power plug 30 is inserted into the hole 2' in the base body 2 of the power jack 1 so that the locking nose 32 engages the groove 5. The power plug 30 is then twisted relative to the power jack 1, following the path (not shown) of the spiral groove 5 in the body 2 of the power jack 1. Nevertheless, the release torque is typically low, making it highly likely that the power plug 30 will unintentionally detach from the power jack 1 of the power coupling 50. Temperature changes and mechanical forces acting on the components of the power coupling 50 increase the risk of loosening. A loose connection increases the contact resistance, which can lead to local overheating of the power plug 30, the power jack 1 and / or the power cable 40, potentially destroying some of these components. This situation can be improved, for example, by using resiliently mounted locking lugs 32, but this still does not eliminate unintentional unplugging.

[0031] Figure 2 shows a cross section of the prior art power coupling 50 according to Figure 1, with the power plug 30 and power jack 1 connected. Here it can be seen how the locking nose 32 on the substantially cylindrical pin 31 of the power plug 30 protrudes into the helical groove 5 in the base body 2 of the power jack 1. Furthermore, a device 4 for connection to a power cable 40 within the power jack 1 can be seen in the form of a screw joint 16. The power jack 1 comprises a sheath 13 made of an electrically insulating material.

[0032] FIG. 3 is an exploded perspective view of a power jack 1 according to the present invention. The power jack 1 includes a body 2 made of an electrically conductive material, a bushing 3 with a spiral groove 5, and a receptacle 3' for the bushing 3. In the illustrated embodiment, the receptacle 3' for the bushing 3 includes two connectable portions 11 and 12. The portions 11 and 12 of the receptacle 3' of the base body 2 are made of, for example, brass or a brass alloy, and include a sheath 13 (not shown) made of an electrically insulating material. The bushing 3 is preferably made of a harder material than the receptacle 3', for example, steel or a steel alloy. The substantially cylindrical bushing 3 is used for insertion of a substantially cylindrical pin 31 of a power plug 30 (not shown). To prevent twisting of the bushing 3 relative to the receptacle 3' of the base body 2, positioning elements 9, in particular axial latching noses 10, are arranged on the bushing 3, which protrude into corresponding recesses 18 in the part 11 of the receptacle 3' of the base body 2. A device 4 for connecting to the power cable 40, e.g. a screw joint 16, is not shown in detail. According to the invention, to accommodate the locking noses 32 of the power plug 30, a spiral groove 5 is arranged on the bushing 3, which comprises at least two regions a, c with a positive slope and regions b, d with a negative slope, with regions b, d with a negative slope arranged at the end of each positive slope region a, c, forming a respective latching step (see FIG. 4A).

[0033] Optionally, a spring element 6 can be arranged in the base body 2 for spring support of the bushing 3 in the axial direction X of the receptacle 3' of the base body 2, which in the example shown is formed by two wire spring washers 7 and two spacer rings 8. This allows to increase the holding force in the locked state and thus to prevent or hinder unintentional disconnection of the connection.

[0034] The structure of the spiral groove 5 can be better appreciated from the enlarged unwound side view of the bushing 3 of the embodiment of the power jack 1 shown in FIG. 4A and three different views of the bushing 3 shown in FIGS. 4B-4D. Thus, the spiral groove 5 of the bushing 3 includes at least two regions of positive slope, a and c, with negative slope regions b and d located at the ends of the positive slope regions a and c to form latching steps, respectively, and a region e with no slope or no significant slope located at the end of the positive slope regions a and c. Thus, the illustrated bushing 3 achieves two latching steps. By providing the bushing 3 of the power jack 1 with a spiral groove 5 having at least two regions of positive slope, a and c, and by providing negative slope regions b and d at the ends of each positive slope region a and c, the operator can receive tactile feedback when the respective latching steps are reached. For proper latching, the region e with no slope between the positive slope regions a and c and the negative slope regions b and d may or may not be provided. However, these gradientless regions e are not necessarily required. Also, the gradients between the positive gradient regions a and c and the negative gradient regions b and d may be stepped, i.e., the gradient is not necessarily constant, but may, for example, increase or decrease.

[0035] 5 shows a cross section of the assembled power jack 1 shown in FIG. 3. Therefore, the two parts 11, 12 of the receptacle 3' of the base body 2 of the power jack 1 are connected to each other, for example, by an interference fit. The bushing 3 is disposed inside the receptacle 3' of the base body 2 and is mounted displaceably in the axial direction X relative to the receptacle 3' by a spring element 6 in the form of two wire spring washers 7 and two spacer rings 8. This results in a greater force acting on the front surface 14 of the receptacle 3' when the power jack 1 is connected to the power plug 30. The front surface 14 of the receptacle 3' of the base body 2 can be provided with a coating 15, for example, of silver, which reduces the contact resistance R U is further reduced and corrosion is prevented.

[0036] 6 shows a cross section of the power coupling 50 when the power plug 30 is not yet latched to the power jack 1. The two wire spring washers 7 of the spring element 6 are therefore loose. In the power plug 30, a continuous hole 17 for guiding a shielding gas or the like is arranged in the receptacle 3' of the base body 2, which extends in the axial direction X within the power jack 1.

[0037] 7 shows a cross section of the power coupling 50 with the power plug 30 shown in FIG. 6 latched onto the power jack 1. In this state, the wire spring washer 7 of the spring element 6 is compressed, and the spring force is transmitted to the front surface 14 of the receptacle 3' of the base body 2 of the power jack 1. As a result, the contact resistance R of the connection of the power coupling 50 is U can be reduced.

[0038] FIG. 8 shows a force-displacement preload diagram with two latching steps (curve C) for a power coupling 50 with a power jack 1 designed according to the present invention compared to a power coupling 50 with a conventional power jack 1 (curves A and B). The force F in N is plotted against the distance s in mm. In conventional plug connections, such as a typical DINSE® connector (curve A), the force F increases very sharply as a function of the distance s. The curves for closing and opening the plug connection are essentially the same. With further development of plugs with spring-loaded locking lugs (curve B), the curve of force F as a function of distance s becomes flatter. The curve for force F during disconnection is lower than the curve for force F during plug connection. Therefore, the release torque is smaller than the tightening torque. The power coupling 50 with a power jack 1 according to the present invention (curve C) produces a force-displacement curve consisting of two latching steps with two negative slope regions due to the aforementioned path of the spiral groove 5 in the bushing 3. In the latched state of the plug connection, a smaller force F occurs in both cases. Therefore, in order to open the connection according to the present invention and remove the power plug 30 from the power jack 1, a certain force F must be overcome, which improves the retention of the plug connection and significantly reduces the risk of the plug connection being unintentionally disconnected.

[0039] Finally, FIG. 9 shows the contact resistance R of the power coupling 50 equipped with the power jack 1 according to the present invention. U and power loss P V 1. Bar graph I shows an example of a power coupling 50 with a power jack 1 according to the present invention compared to a power coupling 50 with a conventional plug connection (bar graphs II-IV). U and power loss P V The contact resistance R U and power loss P V The bar graph for II shows the contact resistance R of the conventional DINSE® connector in the fixed optimum connection. U and power loss P V The contact resistance RU and power loss P V The values of I and III are comparable to those of the power jack 1 of the present invention, which are several tens of μΩ and several W, respectively. When the DINSE® connector is in a loose state (bar graph according to III), the contact resistance R U and power loss P V The bar graph for IV shows that the DINSE® connector is loose and also oxidized. Therefore, the contact resistance R U and power loss P V and R increase rapidly, for example, to several hundred μΩ and approximately 100 W, respectively. Such values may lead to destruction of the power coupling 50 due to local overheating. In contrast, the power jack 1 according to the present invention has a minimum contact resistance R U and minimum power loss P V This ensures an optimal, stable and permanent connection, thereby minimizing the risk of damage to the components of the power coupling 50, the power cable 40 and the connected equipment, as well as the risk of injury to the user.

Claims

1. A power jack (1) for detachably connecting to a power plug (30), comprising a body (2) made of an electrically conductive material having a hole (2') for accommodating a substantially cylindrical pin (31) of the power plug (30) and provided with a device (4) for connecting to a power cable (40); A spiral groove (5) for receiving a locking nose (32) of a power plug (30) is arranged in the base body (2), and the base body (2) includes a bushing (3) with the spiral groove (5) and a receptacle (3') for the bushing (3); The spiral groove (5) includes at least two regions (a, c) having a positive slope and regions (b, d) having a negative slope, the regions (b, d) having a negative slope being disposed at the end of each region (a, c) having a positive slope to form a respective latching step, the receptacle (3') being formed from a metal or metal alloy having a sheath (13) of an electrically insulating material, and the bushing (3) being formed from a material harder than the receptacle (3').

2. The power jack (1) according to claim 1, characterized in that a spring element (6) is arranged in the receptacle (3') so as to spring-support the bushing (3) of the base body (2) in the axial direction (X) of the receptacle (3').

3. 3. A power jack (1) according to claim 2, characterized in that the spring element (6) is formed by at least one wire spring washer (7).

4. 4. The power jack (1) according to claim 3, characterized in that the spring element (6) is formed by two wire spring washers (7) and a spacer ring (8) arranged between the wire spring washers (7).

5. The power jack (1) according to any one of claims 1 to 4, characterized in that the bushing (3) comprises positioning elements (9), in particular axial latching noses (10), for preventing twisting of the base body (2) relative to the receptacle (3').

6. The power jack (1) according to any one of claims 1 to 5, characterized in that the receptacle (3') of the base body (2) is composed of two parts (11, 12) that can be connected to each other, and the two parts (11, 12) of the receptacle (3') of the base body (2) are preferably connectable to each other by press-fitting.

7. The power jack (1) according to any one of claims 1 to 6, characterized in that the receptacle (3') is made of steel or a steel alloy, preferably brass or a brass alloy, and the bushing (3) is made of steel or a steel alloy.

8. A power jack (1) according to any one of the preceding claims, characterized in that the receptacle (3') of the base body (2) comprises a flat front surface (14) for contacts.

9. A power jack (1) according to claim 8, characterized in that the front face (14) of the receptacle (3') comprises a coating (15), for example a silver coating.

10. A power jack (1) according to any one of the preceding claims, characterized in that the groove (5) in the bushing (3) extends over a rotation angle of between 90° and 270°.

11. A power jack (1) according to any one of the preceding claims, characterized in that the gradient of the areas (a, c) of the groove (5) with a positive gradient is between 1 mm and 8 mm per 360°.

12. 12. The power jack (1) according to any one of claims 1 to 11, characterized in that the gradient of the region (b, d) of the groove (5) with a negative gradient for forming the latching step is 0.1 to 20 mm per 360°, preferably 1 to 20 mm, particularly preferably 5 to 20 mm.

13. 13. The power jack (1) according to any one of claims 1 to 12, characterized in that the spiral groove (5) comprises a region (e) with no gradient after the region (b, d) with a negative gradient.

14. 14. The power jack (1) according to any one of the preceding claims, characterized in that the device (4) for connection to the power cable (40) is formed by a screw joint (16).

15. The power jack (1) according to any one of claims 1 to 14, characterized in that the receptacle (3') of the base body (2) includes a hole (17) or the like that is continuous in the axial direction (X) for guiding a shielding gas (S) or the like.

16. A power coupling (50) consisting of a power jack (1) and an associated power plug (30) having substantially cylindrical pins (31), A power coupling (50) characterized in that the power jack (1) is designed according to one of claims 1 to 15.

17. 17. The power coupling (50) of claim 16, wherein the bushing (3) of the power jack (1) is made of a harder material than the cylindrical pin (31) of the power plug (30).

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