DE20108417U1 - Connection terminal - Google Patents

Description

Connection terminal

The invention relates to a clamping device for connecting a conductor to a contact element. Such devices are used, for example, to connect electrical conductors to an electrical module, e.g. in the form of a circuit board.

The design and connection technology of electrical and electronic assemblies means that individual conductors must be connected to other conductors or conductor tracks, for example on circuit boards. For this purpose, screw connection clamping mechanisms are used, which have two opposing clamping jaws between which a conductor can be inserted. The clamping jaws are then pressed together using a screw, thereby clamping the conductor. The conductor is connected to a circuit board by plugging the screw connection clamping mechanism onto the circuit board. During screwing, the conductor must be held exactly in its position between the clamping jaws, which is very cumbersome and time-consuming for the operator.

Conductor connection clamping devices in the form of spring clamp connection mechanisms are also known. In such mechanisms, the conductor is pressed against a contact bracket by means of a clamping spring, which can be in conductive connection with a circuit board. To insert the conductor into the spring clamp connection mechanism, the clamping spring is brought into an open position by means of a rotating eccentric lever. If the pressure of the eccentric lever on the clamping spring is reduced, the clamping spring springs back into a clamping position and presses the conductor against the contact bracket. In comparison to the screw connection clamp mechanism, such spring clamp connection mechanisms produce stable, interference-resistant contacts and increase the reliability of the conductive connection.

The invention is based on the object of developing a clamping device for connecting a conductor to a contact element, which, with simple operation,

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usability ensures a reliable connection with good contact properties.

The object is achieved according to the invention by a clamping device for connecting a conductor to a contact element, in which a spring can be actuated between two positions by means of a translationally and rotationally movable actuating element, wherein the conductor is held in contact with the contact element in a clamping position and can be released from the contact element in an open position, and the actuating element can be locked in at least one locking position.

With such a clamping device, a conductor can be pressed firmly and permanently against the contact element in the clamping position, for example to establish an electrical connection, and in the open position the contact can be broken and the conductor can be removed from the clamping device. Translational and rotary movement mechanisms can be used to move the actuating element, each of which can be based on different movement kinematics. The movement can be composed of a sequence of purely translational, purely rotary, or a combination of both forms of movement. The individual movement mechanisms can be assigned characteristic functions, for example moving the spring into a clamping or an opening position. By locking the actuating element in the locking position, a permanent clamping or opening position can be achieved.

In an advantageous embodiment of the invention, the spring can press against the actuating element under spring preload, with the force of the spring in the open position being directed towards the clamping position. If the actuating element exerts a force on the spring in such a way that it is pressed into the open position against the spring force, a conductor can be inserted into the clamping device. If the force exerted by the actuating element on the spring decreases, the spring brings the conductor into contact with the contact element during the transition from the open to the clamping position.

In a favorable variant of the invention, the actuating element can be moved from a non-locking position to the locking position by means of a purely translational or purely rotational movement. This allows different functions of the clamping device to be divided between the respective movement forms of the actuating element. For example, one movement form can be used to cover the majority of the spring travel. The other movement form can then be used for locking, for example.

In a preferred example of the invention, the actuating element can have a locking shoulder which, in the locking position, engages behind a housing shoulder. This allows the actuating element to be securely positioned in the locking position, in which it reliably holds the spring in the aforementioned position. The transition to the locking position can optionally be designed in such a way that the actuating element initially presses against the spring, e.g. by executing a translational movement. The spring is thereby brought from a clamping position into the open position. In this position, the actuating element is moved in such a way, e.g. by a rotary movement, that it engages behind a housing shoulder and is locked.

The actuating element can preferably have a holding shoulder which engages with a housing stop in the direction of the clamping position and positions the actuating element in this position. If no force or a force less than the spring force is exerted on the spring via the actuating element, the spring strives to move from the open position to the clamping position and in doing so exerts a force on the actuating element. In this case, the holding shoulder defines an end position of the actuating element in engagement with the housing stop in order to limit the mobility of the actuating element in this direction. In addition, this determines a starting position from which the actuating element can be moved in the opposite direction.

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An advantageous development of the invention can consist in the actuating element having a stop shoulder which engages with a housing stop in the direction of the opening position and specifies the end position of the translational movement. The stop shoulder, in combination with the housing stop, determines how far the actuating element can be moved in the translational direction. This allows the deformation of the spring due to the pressure of the actuating element on the spring and the opening range of the spring that can be achieved as a result to be predetermined.

The invention can be advantageously designed in such a way that a guide consisting of a guide recess and a guide element that can be moved in the guide recess is formed between the actuating element and a housing, the clear displacement path defining the translatory movement stroke of the actuating element. Such a guide determines the path that can be covered by the actuating element in the direction of the clamping position and in the direction of the opening position of the spring.

In a particularly advantageous variant of the invention, the guide can be limited in the direction of displacement of the guide element by a holding shoulder and/or a stopping shoulder. This ensures that the actuating element is guided along a predetermined translational movement path, positioned in the clamping position and/or positioned in the opening position.

According to a particularly favorable embodiment of the invention, the guide element can form a pivot bearing for the rotary movement of the actuating element. Because the pivot bearing also serves as a guide element of a guide for the translatory movement of the actuating element, the pivot bearing can be moved to the desired position in the guide at which the rotation is to be carried out.

In an advantageous embodiment of the invention, it is proposed that a rotary bearing can be formed by a round projection of an inner housing wall or of the actuating element. The round shape of the rotary bearing proves

as advantageous in order to ensure a well-guided rotational movement of the actuating element.

Preferably, a rotary bearing can be provided with a round support surface that forms a guide for the rotary movement of the actuating element. Optionally, the support surface for the rotary bearing has a shape that corresponds to the rotary bearing, which improves the guidance of the rotary movement of the actuating element.

According to a particularly advantageous example of the invention, the support surface can form a stop shoulder that limits the translatory movement of the actuating element. Thus, in addition to being used as a movement-limiting element, the stop shoulder can serve as a guide for the rotary movement of the actuating element.

In a favorable variant of the invention, the actuating element can have at least one sliding surface which, for the translational movement, is in sliding contact with a counter-sliding surface of a housing. The sliding surface in combination with the counter-sliding surface guides the translational movement of the actuating element within the housing.

According to a preferred embodiment of the invention, a contact surface can be formed on the actuating element adjacent to the sliding surface, the surfaces being arranged in a gable-like manner to one another and enclosing an angle α between them, the opposite angle β of which corresponds approximately to the angle of rotation of the rotary movement of the actuating element. The limits of the rotary movement can thus be determined approximately by the gable-like construction of the actuating element and the surfaces surrounding the actuating element.

It is further proposed that the actuating element may have a pressure surface via which a force can be transmitted directly or indirectly to the spring

This pressure surface can be directly adjacent to the spring or can transfer forces to the spring via one or more elements.

In a particularly preferred embodiment of the invention, the pressure surface can have an arc shape, the center of which is approximately the pivot point of the rotary movement of the actuating element. This allows the actuating element to be moved relative to the spring by a rotary movement while the position of the spring remains approximately the same and thus, for example, to assume the locking position. The actuating element slides past the spring at approximately the same distance.

The actuating element can preferably have a test socket via which a conductive test connection can be established from outside the clamping device. The test socket is used to determine whether a conductive connection exists or to test voltage and current values. It ensures accessibility for a user from outside.

The invention can advantageously be designed such that the test socket is at least partially designed as a channel in the actuating element. Such a channel ensures that a test probe or the like can reach through the channel to a conductive connection to the conductor.

In the invention, it is further proposed as an advantageous variant that the test socket is directed towards the spring in its extension in the clamping and/or opening position. This allows a test probe or the like to be guided through the test socket to the spring, which is in contact with the contact element in the clamping position. If the conductor is clamped between the contact element and the spring, the test element can establish a conductive connection to the conductor via this specially aligned test socket.

Embodiments of the invention are illustrated in the figures of the drawing and are explained below.

Show it:

Figure 1 shows a first embodiment of a clamping device according to the invention in the open position in a perspective view,

Figure 2 shows a longitudinal section through the clamping device in the clamping position along the section line H-II in Figure 1,

Figure 3 is a longitudinal section through the clamping device in the open position along the section line III-III in Figure 1,

Figure 4 shows a second embodiment of a clamping device according to the invention in the open position in a perspective view, and

Figure 5 shows a longitudinal section through the clamping device along the section line V-V in Figure 4, wherein the solid lines represent the clamping position and the dash-dot lines represent the opening position.

Figure 1 shows a first embodiment of the clamping device 1 in perspective view. The clamping device 1 shown has a housing 8. In this there is an opening window 2. A conductor entry 32 is formed in the shape of a collar around the opening window 2. On another side of the housing, approximately at an angle of 90° to the opening window 2, there is an opening 33. An actuating element 3 protrudes partially from the opening of the housing 8. The part of the actuating element 3 that is accessible from the outside has an actuating surface 5. An actuating lever 4 is formed on the actuating element 3, projecting on one side from the actuating surface 5. An opening 6 is provided approximately in the middle of the actuating surface 5.

Figure 2 shows a longitudinal section through the first embodiment of the clamping device 1 in the clamping position. The clamping device 1 shown contains a contact element 9. This has a connection end 42 which protrudes in the form of a pin from the housing 8 of the clamping device 1. The connection end 42 is connected to

The remaining part of the contact element 9 is located inside the housing 8. This has a J-shape and is wound around a positioning aid 39, which holds the contact element 9 between the positioning aid 39 and the housing 8.

The contact element 9 forms two windings 46 and 47. A support part 48 of the contact element 9 is connected to the winding 47. This forms the vertical part of the J-shape.

A leg 45 is provided on the contact element 9 following the support part 48. This is hook-shaped and forms the end of the contact element 9 located in the housing 8. The leg 45 engages behind a housing shoulder 40 and thus positions the contact element 9 within the housing 8.

A spring arm 49 of a spring 10 is located flat against the support part 48 of the contact element 9. The spring arm 49 has approximately the same length as the support part 48 and borders with a spring arm end 44 on the leg 45 of the contact element 9.

A spring coil 50 is connected to the other end of the spring arm 49. The coil 50 is wound around a bearing 41 that is approximately cylindrical in cross section. The coil 50 is in flat contact with the bearing 41 and the housing 8.

A tension part 51 of the spring 10 is connected to the spring winding 50. This tension part 51 has a semicircular curvature. It borders on an angled housing shoulder 52 that projects into the housing interior 53 and a semicircular housing shoulder 54 that is located approximately opposite in the housing and projects into the housing interior 53.

A clamping end 55 of the spring is connected to the tension part 51 and forms the end of the spring 10. The clamping end 55 has an approximately rectangular spring opening 43.

The leg 45 of the contact element 9 and the spring arm end 44 of the spring 10 protrude through the spring opening 43. In the clamping position shown in Figure 2, a clamping end 56 of the spring opening 43 presses against the leg 45 of the contact element 9.

Opposite the clamping end 56, there is an opening end 57 on the spring opening 43. This is located approximately at the same height as the housing shoulder 54. The spring clamping end 55 of the spring 10 projects beyond the spring opening 43 such that it is approximately in line with the opening window 2 in the housing 8 of the clamping device 1 and the positioning aid 39.

Approximately in the middle of the tension part 51 of the spring 10, this borders on a pressure surface 11 of the actuating element 3 in Figure 2. The pressure surface 11 is formed in the shape of a circular arc. Following the pressure surface 11, there is a flattened sliding surface 28 on the actuating element 3. In the embodiment shown, this borders on the counter sliding surface 29 of the housing 8.

A support surface 30 is formed on the actuating element 3 at an angle α to the sliding surface 28. A counter angle β is formed between the support surface 30 and the counter sliding surface 29. The angles α and β together result in an extended angle. In the clamping position, part of the support surface 30 protrudes from the housing 8 at an angle β.

Opposite the contact surface 30, the actuating element 3 has a sliding surface 37. The length of this sliding surface 37 is approximately between that of the sliding surface 28 and that of the support surface 30. The sliding surface 37 partially protrudes from the housing 8. The sliding surface 37 partially rests against a counter sliding surface 38 of the housing 8. On the outside, the sliding surface 37 ends at the actuating lever 4.

The sliding surface 37 is limited inwards by a stop shoulder 17. The stop shoulder 17 has a round shape and is at an angle of approximately 90° to the sliding surface.

before 37. It forms one end of a guide 23, which is designed as a recess in the actuating element 3. The guide 23 is limited relative to the stop shoulder 17 by a holding shoulder 12. Between the holding shoulder 12 and the stop shoulder 17, the guide 23 forms a length L. The holding shoulder 12 forms approximately a right angle to the guide 23.

Following the retaining shoulder 12, a sliding surface 58 is arranged at approximately a right angle and at the same height as the sliding surface 37. The sliding surface 58 is limited by the pressure surface 11.

Adjacent to the retaining shoulder 12, a guide element projects into the guide 23. The guide element 22 is semicircular in shape as a nose projecting from the housing 8 into the housing interior 53.

A test socket 7 is formed in the actuating element 3. The test socket 7 forms a channel 14 through the actuating element 3. The channel 14 is accessible from the outside through the opening 6 in the actuating surface 5. The channel 14 has a channel opening 59 on the inside. The imaginary extension 15 of the channel 14 projects against the tension part 51 of the spring 10.

Figure 3 shows a longitudinal section through the first embodiment of the clamping device 1 in the open position. In this illustration, the sliding surface

37 inside the housing 8. It forms approximately the angle β to the counter sliding surface

38. The support surface 30 of the actuating element 3 rests on the counter sliding surface 29 of the housing 8. The sliding surface 28 forms approximately the angle β to the counter sliding surface 29.

One side of the guide element 22 forms a housing stop 18 against which the stop shoulder 17 abuts. The holding shoulder 12 engages behind a housing shoulder 26 and functions as a locking shoulder 25. The sliding surface 58 rests against a locking surface 60 of the housing 8.

In the open position shown in Figure 3, the guide element 22 is designed as a pivot bearing 19 with a center point 27 and a radius 61. The center point 27 of the pivot bearing 19 corresponds to the pivot point of the pressure surface 11 of the actuating element 3. The difference between the length L of the guide 23 and twice the radius R corresponds approximately to the translational displacement path of the actuating element and thus to the spring travel.

The pressure surface 11 of the actuating element 3 borders on the tension part 51 of the spring 10. The spring 10 is pre-tensioned by the actuating element 3.

In the open position, the spring opening 43 is aligned with the opening window 2. The opening end 57 of the spring opening 43 borders on the spring arm end 44 of the spring 10. In the open position, the spring 10 rests with the spring coil 50 on the housing 8 and is also held in its position by the support part 48 of the contact element 9 and the pressure surface 11 of the actuating element 3.

In the following descriptions of the figures, the same reference numerals as in figures 1 to 3 identify the same elements of the clamping device. The above statements for figures 1 to 3 apply accordingly to these elements. The following descriptions of the figures are primarily limited to the different designs of elements compared to figures 1 to 3.

Figure 4 shows a second embodiment of a clamping device 31 according to the invention in a perspective view. The clamping device 31 has a housing 62. The opening window 2 and the opening 33 are provided on different sides of the housing 62. An actuating element 35 partially protrudes from the opening 33. The actuating element 35 is flush with the actuating surface 5 on the outside. The opening 6 is located approximately in the middle of the actuating surface 5.

Figure 5 shows a longitudinal section through the second embodiment of the clamping device of Figure 4, wherein the solid lines show the clamping position and the

Dash-dot lines represent the opening position. For the sake of clarity, the spring 10 is only shown in the clamping position in Figure 5.

The actuating element 35 has an extended sliding surface 36. In the clamping position, this is in contact with the counter sliding surface 29. In the open position, the extended sliding surface 36 forms an angle β with the counter sliding surface 29. The contact surface 30 adjoins the extended sliding surface 36. In the clamping position, this is formed approximately at the angle β to the counter sliding surface 29. In the clamping position, it protrudes almost completely from the housing 62. In the open position, the contact surface 30 rests almost completely on the counter sliding surface 29. The extended sliding surface 36 has a length X that corresponds approximately to the length L of the guide 23.

The guide 23, which is arranged on the actuating element 35 opposite the extended sliding surface 36, has a retaining shoulder 34 as a limit of the guide 23 in the direction of the clamping position. The retaining shoulder 34 has a pronounced corner 63. Thus, in the clamping position, only the housing stop 13 of the guide element 22 rests against the retaining shoulder 34. In the open position, the retaining shoulder 34 with the pronounced corner 63 fits precisely behind the housing shoulder 26.

Adjacent to the guide element 22, a holding surface 64 protruding into the housing interior 53 is formed in the housing 62. In the clamping position, the sliding surface 58 of the actuating element 35 rests against the holding surface 64. The holding surface 64 is slightly longer than the sliding surface 58 and projects beyond it with the housing shoulder 26. In the open position, which is identical to the locking position in the illustration shown, the sliding surface 58 rests against the locking surface 60 of the housing 62.

The housing 62 has a housing shoulder 52' which is reinforced compared to Figures 2 and 3 and which is not in contact with the spring 10 in either the open or clamped position. Approximately opposite the housing shoulder 52", the device has

housing 62 has a reduced housing shoulder 54' which, in contrast to the housing shoulder 54 shown in Figures 2 and 3, is not in contact with the spring 10 in either the clamping or the opening position.

In the following, the functioning of the clamping device is described using the embodiments of the clamping device 1 and 31 shown in Figures 1 to 5.

In Figure 2, the spring 10 is shown in the clamping position. In this position, a spring force F1 presses the clamping end 56 of the spring opening 43 against the leg 45 of the contact element 9. The tension part 51 of the spring 10, which is in contact with the pressure surface 11 of the actuating element 3, partially presses the actuating element 3 out of the housing 8 through the opening 33 in the direction of the clamping position.

The actuating element 3 engages behind the housing stop 13 with the holding shoulder 12 and is thereby held in its position in the housing 8. The actuating element 3 can thus counteract the spring force F1 with a counterforce F2.

By applying force to the actuating surface 5 or the actuating lever 4 of the actuating element 3 in the direction of the opening position, the actuating element 3 performs a purely translational movement. The translational movement is limited by the stop shoulder 17 striking the housing stop 18.

The force F2 transmitted through the pressure surface 11 to the tension part 51 of the spring 10 causes the spring 10 to be continuously deformed during the translatory movement of the actuating element 3. At the end of the deformation or spring travel, the spring 10 has the shape shown in Figure 3.

In the open position, the spring opening 43 of the spring 10 is aligned with the opening window 2 of the housing 8. This allows a conductor (not shown) to be introduced into the clamping device 1 through the opening window 2 and the spring opening 43.

Figure 3 shows the opening position of the spring in the locking position. The transition from the non-locked opening position to the locking position is achieved by a force F3, which is applied approximately perpendicular to the direction of the opening position on the actuating element 3, by pressure on the actuating lever 4 or the actuating surface 5.

The actuating element is rotatably mounted by the housing stop 18 designed as a pivot bearing 19 and the stop shoulder 17 designed as a support surface 21 so that a rotary movement of the actuating element 3 is triggered by the force F3. The locking shoulder 25 engages behind the housing shoulder 26 until the sliding surface 58 rests on the locking surface 60. The spring 10 presses with the force F1 against the pressure surface 11 of the actuating element 3 and thus presses the actuating element 3 against the housing shoulder 26.

The transition from the locking position to the unlocked position is achieved by rotating the actuating element in the opposite direction. The center of the pivot bearing 19 corresponds to the pivot point 27 of the pressure surface 11. The pressure surface 11 slides past the spring 10 during the rotary movement of the actuating element in such a way that the shape of the spring is not affected in the open position.

If the actuating element is released from the locking position, the spring presses against the actuating element with the force F1 so that the actuating element is partially pushed outwards from the housing 8 through the opening 33 in the direction of the clamping position. The actuating element performs a translational movement, the displacement path of which is predetermined by the guide 23 in combination with the guide element 22. The displacement path is calculated from the length L of the guide 23 minus twice the radius R of the guide element 22.

While the actuating element performs a translational movement in the direction of the clamping position of the spring, the spring relaxes continuously. It brings the conductor introduced through the spring opening 43 against the contact element 9. In

In the clamping position, the conductor rests against the contact element 9 in such a way that an electrical connection exists between the conductor and the contact element 9.

This electrical connection can be tested using the test socket 7. For this purpose, for example, a test probe is inserted into the opening 6 of the actuating surface 5 of the actuating element 3 in the channel 14 of the test socket 7. The test probe or a similar measuring instrument is brought through the channel 14 and the channel opening 59 and reaches the extension 15 to the tension part 51 of the spring. In the clamped position, this is in direct contact with the conductor.

The second embodiment of Figures 4 and 5 functions analogously.

Claims (19)

1. Clamping device ( 1 , 31 ) for connecting a conductor to a contact element ( 9 ), in which a spring ( 10 ) can be actuated between two positions by means of a translatorily and rotatorily movable actuating element ( 3 , 35 ), wherein the conductor is held in contact with the contact element ( 9 ) in a clamping position and can be released from the contact element ( 9 ) in an open position, and the actuating element ( 3 , 35 ) can be locked in at least one locking position. 2. Clamping device according to claim 1, characterized in that the spring ( 10 ) presses against the actuating element ( 3 , 35 ) under resilient prestress, the force effect of the spring ( 10 ) in the open position being directed in the direction of the clamping position. 3. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) can be transferred from a non-locking position into the locking position by means of a purely translational or purely rotational movement. 4. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has a locking shoulder ( 25 ) which, in the locking position, engages behind a housing shoulder ( 26 ). 5. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has a holding shoulder ( 12 ) which engages with a housing stop ( 13 ) in the direction of the clamping position and positions the actuating element ( 3 , 35 ) in this position. 6. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has a stop shoulder ( 17 ) which engages with a housing stop ( 18 ) in the direction of the opening position and specifies the end position of the translatory movement of the actuating element ( 3 , 35 ). 7. Clamping device according to one of the preceding claims, characterized in that a guide ( 23 ) consisting of a guide recess ( 24 ) and a guide element ( 22 ) displaceable in the guide recess ( 24 ) is formed between the actuating element ( 3 , 35) and a housing ( 8 , 62 ), wherein the clear displacement path specifies the translatory movement stroke of the actuating element ( 3 , 35 ). 8. Clamping device according to claim 7, characterized in that the guide ( 23 ) is limited in the displacement direction of the guide element ( 22 ) by a holding shoulder ( 12 ) and/or a stopping shoulder ( 17 ). 9. Clamping device according to at least one of claims 7 or 8, characterized in that the guide element ( 22 ) forms a rotary bearing ( 19 ) for the rotary movement of the actuating element ( 3 , 35 ). 10. Clamping device according to one of the preceding claims, characterized in that a rotary bearing ( 19 ) is formed by a round projection of an inner housing wall ( 20 ) or of the actuating element ( 3 , 35 ). 11. Clamping device according to one of the preceding claims, characterized in that a rotary bearing ( 19 ) with a round bearing surface ( 21 ) is provided, which forms a guide ( 23 ) for the rotary movement of the actuating element ( 3 , 35 ). 12. Clamping device according to claim 11, characterized in that the support surface ( 21 ) forms a stop shoulder ( 17 ) limiting the translational movement of the actuating element ( 3 , 35 ). 13. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has at least one sliding surface ( 28 , 36 , 37 ) which, for the translational movement, is in displaceable contact with a counter-sliding surface ( 29 , 38 ) of a housing ( 8 , 62 ). 14. Clamping device according to claim 13, characterized in that a contact surface ( 30 ) is formed adjacent to the sliding surface ( 28 ), the surfaces being arranged in a gable-like manner to one another and an angle α being formed between them, the opposite angle β of which corresponds approximately to the angle of rotation of the rotary movement of the actuating element ( 3 , 35 ). 15. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has a pressure surface ( 11 ) via which a force is transmitted directly or indirectly to the spring ( 10 ). 16. Clamping device according to claim 15, characterized in that the pressure surface ( 11 ) has an approximately circular arc shape, the center ( 27 ) of which is approximately the pivot point of the rotary movement of the actuating element ( 3 , 35 ). 17. Clamping device according to one of the preceding claims, characterized in that the actuating element ( 3 , 35 ) has a test socket ( 7 ) via which a conductive test connection can be established from outside the clamping device ( 1 , 31 ). 18. Clamping device according to claim 17, characterized in that the test socket ( 7 ) is at least partially designed as a channel ( 14 ) in the actuating element ( 3 , 35 ). 19. Clamping device according to claim 18, characterized in that the test socket ( 7 ) in the clamping and/or opening position is directed towards the spring ( 10 ) in its imaginary extension ( 15 ).