Spring contact pin

Abstract

The invention relates to a spring contact pin (1) for electrically conductively contacting a contact partner, having a sleeve-shaped housing (2) and a contact element (3) which is supported in a longitudinally displaceable manner in the housing (2) and has a plunger (6), which lies at least partially in the housing (2), and a contact head (4), which lies outside the housing (2) and has a contact surface (5) for contacting the contact partner, wherein a spring element (14), in particular a coil spring, is arranged in the housing (2) in such a manner that the contact element (3) can compressingly engage into the housing (2). According to the invention, the plunger (6) is designed in a tubular manner as a hollow plunger and the contact surface (5) of the contact head (4) is designed in a closed manner.

Description

[0001] DESCRIPTION

[0002] Spring contact pin

[0003] The present invention relates to a spring contact pin for electrically conductive contact with a contact partner, with a sleeve-shaped housing and with a contact element mounted longitudinally displaceably in the housing, which has a piston located at least partially in the housing and a contact head located outside the housing with a contact surface for contact with the contact partner, wherein a spring element, in particular a helical spring, is arranged in the housing such that the contact element can spring into the housing.

[0004] Such conventional spring contact probes are used, for example, to test the functionality of electrical or electronic components such as circuit boards or the like. The spring contact probes prevent overloading of the contact point by compressing the probe into the housing. If several spring contact probes are used side by side, all contact points of the opposite contact partner can be reliably contacted, as the spring contact probes can optimally compensate for tolerances by compressing the respective contact element. Spring contact probes are therefore manufactured and used in large quantities. Spring contact probes are also subject to mechanical wear, which occurs when the contact element compresses into the housing.Wear occurs particularly through the contact element, in particular the piston, spring element and housing, rubbing against each other when the piston is pushed into the housing against the force of the spring element. However, for the electrical conductivity of the spring contact pin, secure and permanent contact between piston and housing is advantageous. Typically, the individual components of the spring contact pin are designed to be electrically conductive and, if necessary, provided with electrically conductive coatings to offer the lowest possible electrical resistance. Mechanical and electrical functions or malfunctions influence each other. Wear of the mechanism is always associated with damage to the surfaces and any coatings or finishes present, such as precious metallization. This results in the loss of contact medium and the electrical resistance increasing.In addition, wear particles can accumulate, impairing mechanical and electrical function. To prevent fretting corrosion, it is known, for example, to apply protective coatings to the contact points or to apply lubricants.

[0005] The present invention is based on the object of creating an improved spring contact pin which has a longer service life than known spring contact pins due to reduced wear, without impairing the electrical conductivity.

[0006] The object underlying the invention is achieved by a spring contact pin having the features of claim 1. This has the advantage that wear on the spring contact pin is reduced by a simple design measure without compromising the electrical conductivity and thus the functionality of the spring contact pin. Rather, the conductivity is increased by the inventive design of the spring contact pin.

[0007] According to the invention, this is achieved in that the piston is tubular as a hollow piston and in that the contact surface of the contact head is closed. By designing the piston as a hollow piston, so that the piston is tubular or sleeve-shaped, a weight saving results in the contact element so that less mass has to be moved during the conversion process. This means that the spring element can be designed with a reduced spring force, whereby the forces acting in the spring contact pin during a contact process are reduced. This also reduces the contact forces and thus the wear in the spring contact pin. This results in the advantages mentioned above. Because the contact head or its contact surface is closed, the tubular design of the piston does not result in any disadvantage when making contact with the contact partner.With a tubular design of the contact element, the contact head would always have an opening created during the forming of the contact element to form the contact head. The closed design significantly increases the accuracy of the contact element or spring contact pin, ensuring a reliable electrical contact or a secure electrically conductive connection at all times.

[0008] The contact head is preferably designed as a solid element or solid body, i.e., it has no hollow space. Furthermore, the contact head according to the invention has a plug-in section that is axially inserted into the piston. This two-part design of the contact element allows the tubular piston to be manufactured independently of the contact head. This offers advantages both in terms of the manufacturing process and the variability of the design of the contact element. For example, a large number of different contact heads can be connected to one and the same piston. In particular, a spring contact pin system is offered that has a large number of pistons and contact heads, with at least two of the contact heads being designed differently. This allows the specialist to select between suitable contact heads during assembly, for example, depending on the contact partner to be contacted or other boundary conditions.

[0009] The piston is preferably designed as a deep-drawn part. The two-part design of the contact element makes it possible to use the well-known deep-drawing technique for the piston as well. The deep-drawing process is well-known as such and has proven itself over decades for similarly shaped elements. The deep-drawing process allows particularly tight tolerances to be selected, which ensure improved interaction between the contact element, in particular the piston, and the housing. Furthermore, the design as a hollow piston, particularly in the form of a deep-drawn part, allows the wall of the hollow piston to be very thin without risking critical losses in the strength or load-bearing capacity of the contact element. The material used is therefore many times lower than for solid-body pistons.

[0010] Furthermore, it is preferably provided that the plug-in section for the electrical and mechanical connection to the piston is held in / on the piston in a force-fitting, form-fitting, and / or material-fitting manner. The piston and the contact head are thus firmly connected to one another, ensuring the secure cohesion of the spring contact pin, in particular the contact element, even during operation or a testing process.

[0011] Particularly preferably, the plug-in section is secured in / to the plunger by pressing, flanging, crimping, welding, and / or soldering. This results in a permanently captive connection between the plunger and the contact head with advantageous electrical conductivity.

[0012] According to a preferred development of the invention, the piston has a cross-sectional taper between its ends, wherein the spring element extends into the piston and is axially supported on the cross-sectional taper on the one hand and on a housing end facing away from the piston on the other. The spring element is thus axially preloaded between the housing end and the piston, wherein for this purpose the spring element is supported on the cross-sectional taper of the piston. The cross-sectional taper is not located at one of the ends, but between the ends of the piston, so that the spring element extends into the piston, wherein the tubular shape of the piston easily allows the spring element to be accommodated. The arrangement of the spring element in certain areas within the piston has the advantage that parts of the spring element are not guided through the housing, but solely through the piston.This prevents wear or friction on these parts of the spring element when interacting with the housing. This protects the contact points of the housing, which would otherwise be touched by the piston itself during its displacement, from excessive wear.

[0013] Furthermore, it is preferably provided that the cross-sectional taper of the piston is arranged closer to the head, viewed in the axial direction, than to the end of the piston facing the housing end. This results in a region of the spring element, viewed in its axial direction, being guided within the piston and thus reducing wear. The spring force is not impaired.

[0014] The spring element preferably has at least one rigid spring element section. In the rigid spring element section, elastic deformation of the spring element during a contacting process is prevented. In this respect, the rigid spring element section is understood to be a section of the spring element in its longitudinal extension in which compression in the longitudinal extension is not or hardly possible. In addition, deformation transverse to the longitudinal extension is at least substantially prevented by the rigid design, so that the spring element cannot buckle or bend laterally in the rigid spring element section. The rigid spring element section thus defines a region of the spring element which, on the one hand, exerts no spring force during the testing process and, on the other hand, prevents deformation of the spring element.For example, by advantageously positioning the stiff spring element section, wear in the area where the spring element transitions from the housing to the contact piston can be reduced.

[0015] The rigid spring element section is preferably located at least substantially between the piston and the housing end. At least in the unactuated state of the spring contact pin, the rigid spring element section lies completely between the piston and the housing end, viewed in the longitudinal extension of the spring element. This enables and ensures compression by the spring element section, which remains particularly within the piston. The fact that the rigid spring element section lies outside the piston or at least substantially outside the piston reduces or prevents deformation of the spring element there such that it comes into contact, in particular frictional contact, with the housing or its inner wall. The larger the spring element section of the spring element within the piston, the more the overall wear of the spring contact pin is reduced.The rigid spring element section preferably has an outer diameter that is smaller than the inner diameter of the housing, thus preventing physical contact, particularly frictional contact, between the rigid spring element section and the housing. This limits frictional contact of the spring contact pin, particularly to the interaction between the housing and the piston.

[0016] Preferably, the piston has an insertion bevel for the spring element at its end facing the housing. This simplifies the longitudinal insertion of the spring element into the piston during compression. In particular, this prevents wear and, in particular, also prevents the spring element from catching or jamming on the end of the piston facing the housing end. Rather, the insertion bevel centers or guides the spring element into the piston.

[0017] Furthermore, it is preferably provided that the housing end of the housing is plastically deformed, in particular bent, to form an axial stop for the spring element. The advantageous design of the housing end enables easy assembly of the spring contact pin. In particular, the housing end is not yet bent during assembly, so that the contact element can be inserted or is pushed into the housing from behind, i.e. through the housing end. Only then is the housing end plastically deformed to provide an axial stop for the spring element and to prevent the piston from falling out of the housing in the direction of the housing end. This achieves an assembly improvement using simple, cost-effective means that is also space-saving and reliable.

[0018] According to a preferred development of the invention, the housing has a cross-sectional taper forming a step at its end facing away from the housing end, wherein the step is designed as an axial stop for the piston, which acts against the force of the spring element. The piston is thus held longitudinally displaceably between the spring element supported on the housing end, on the one hand, and the axial stop, on the other. Thus, the piston cannot be ejected by the spring element on the side of the housing facing away from the housing end. Due to this structurally simple design, the spring contact pin is cost-effective and less prone to defects. In particular, the cross-sectional taper of the housing is produced using a deep-drawing process. In particular, the housing as a whole is produced using a deep-drawing process. This allows the housing to be manufactured easily and precisely in large quantities.

[0019] According to a preferred development of the invention, the length of the distance of the piston, which lies at least in the housing, corresponds to the length of the housing less the maximum permissible spring travel of the spring element and less a predeterminable tolerance value. As a result, the piston extends almost completely through the housing. Because the spring element runs inside the piston, this does not have a disadvantage for the spring travel. However, the long design of the piston in relation to the housing ensures improved mounting of the piston in the housing, while at the same time improving the electrical connection between the housing and the piston. Because the spring travel and a predeterminable tolerance value are taken into account when defining the length of the piston, it is guaranteed that the desired minimum or maximum spring travel is always achieved.

[0020] Preferably, the end of the spring element facing the housing is widened. This provides improved support for the spring element at the housing end. In particular, as described above, the housing end is subsequently deformed by a forming process to form an axial stop, leaving an opening in the housing end. The wider the spring element is at the point where it rests against the housing end, the less likely it is that the spring element will enter the opening and become caught and / or jammed therein. Widening the missing element thus results in improved support.

[0021] Furthermore, it is preferably provided that the spring element has a longitudinal section outside the piston, along which the outer diameter of the spring element widens toward the housing end, so that the spring element rests against the inner wall of the housing outside the piston. In this case, the spring element is guided radially both inside the piston by the piston and outside the piston by the housing, thereby ensuring particularly secure guidance of the spring element, preventing it from bending. However, this increases wear between the spring element and the housing.

[0022] Therefore, according to an alternative embodiment of the invention, this longitudinal section is particularly preferably designed as the rigid section of the spring element. The rigid spring element section is thus located outside the piston. Because the spring element section is designed to be rigid, no relative movement occurs between the spring element section or the coils of the helical spring and the housing during a spring action. Instead, the spring is held primarily in the piston and less or not at all in the housing. The spring function is ensured in particular by the section of the spring element that is located inside the piston. This also has the advantage of preventing the spring element from bending or buckling sideways.Preferably, the rigid spring element section is formed by the coils of the helical spring abutting each other axially, thereby preventing compression in the axial direction because the applied coils act like a continuous rod.

[0023] According to a preferred development of the invention, the piston has a cross-sectional taper at its end facing the housing, against which the spring element is supported. In contrast to the cross-sectional taper located between the two ends of the piston, this embodiment provides that the spring element does not extend into the piston. While the advantages of the spring contact pin in terms of reduced weight, reduced spring force, and reduced wear between the piston and housing remain, somewhat increased wear occurs due to the elastically deformable part of the spring element being located outside the piston. Nevertheless, this allows the spring element to be manufactured even more cost-effectively, since, for example, the spring element length can be reduced compared to the previous embodiment.

[0024] According to this embodiment, the cross-sectional taper preferably has a centering bevel for centering the spring element between the piston and the housing. This radially centers or captures the spring element between the piston and the housing, ensuring secure guidance of the spring element and the piston in the housing. In particular, the centering bevel has an inner diameter that is smaller than the inner diameter of the spring element, so that the centering bevel can be inserted into the spring element in certain areas.

[0025] Furthermore, it is preferably provided that the spring element has a diameter taper at its end facing the piston for centering the spring element on the piston. According to an alternative embodiment, the spring element thus penetrates partially into the piston in order to be centered therein. This results in the advantages already mentioned above with regard to centering. Further advantages and preferred features and combinations of features emerge in particular from the above description and from the claims. The invention will be explained in more detail below with reference to the drawing.

[0026] Figures 1A to E show a first embodiment of an advantageous spring contact pin,

[0027] Figure 2 shows a second embodiment of the spring contact pin,

[0028] Figures 3A and B show a third embodiment of the spring contact pin,

[0029] Figure 4 shows a fourth embodiment of the spring contact pin,

[0030] Figure 5 shows a fifth embodiment of the spring contact pin,

[0031] Figure 6 shows a sixth embodiment of the spring contact pin,

[0032] Figure 7 shows a seventh embodiment of the spring contact pin,

[0033] Figure 8 shows an eighth embodiment of the spring contact pin and

[0034] Figures 9A and B show a ninth embodiment of the spring contact pin, each in a simplified longitudinal section.

[0035] Figure 1A shows a simplified longitudinal section of an advantageous spring contact pin 1, which has a sleeve-shaped housing 2, also called a shell, and a contact element 3 mounted longitudinally displaceably in the housing 2. The contact element 3 has a contact head 4 with a closed contact surface 5 on the end face, which is designed to make electrically conductive contact with a contact partner by touch contact. For this purpose, the contact head 4 is manufactured as a solid element or solid body (i.e., without cavities), so that the contact surface 5 is also closed. According to the present exemplary embodiment, the contact surface 5 is spherical. In principle, the contact surface 5 can also have other shapes, for example, concave, pointed, conical, star-shaped, or fork-shaped.

[0036] Furthermore, the contact element 3 has a piston 6 which is firmly connected to the contact head 4. The piston 6 is designed as a hollow piston and is therefore tubular. The piston 6 is therefore also sleeve-shaped and has a thin outer wall, wherein the outer wall of the piston 6 is preferably thinner than the outer wall of the sleeve-shaped housing 2. As Figure 1A shows, the piston 6 projects far into the housing 2, so that it extends at least over half the longitudinal extent of the housing and preferably beyond. The piston 6 has a section 7 facing the contact head 4 and a section 8 assigned to the housing, wherein the section 8 lies completely within the housing 2, and the section 7 projects out of the housing at least in the non-actuated state.

[0037] Figure 1B shows an enlarged view of the spring contact pin 1 in the area of ​​the spring contact pin 1 where the plunger 6 penetrates the housing 2. The housing 2 is open at its end facing the contact head 4 and has a cross-sectional taper 9. In the present case, this cross-sectional taper 9 is realized by a flange 10 of the housing 2.

[0038] The piston 6 also has a cross-sectional taper 11 in its longitudinal extension, so that the section 7 has a smaller outer diameter than the section 8 of the piston 6. Due to the cross-sectional taper 11 and the associated different outer diameters of the piston 6, a step is created in the piston 6, which forms an axial stop

[0039] 12. The outer diameter of the section 8 is larger than the inner diameter of the cross-sectional taper 9 of the housing 2, so that the axial stop 12 interacts positively with the cross-sectional taper 9 in the direction of the contact head 4, so that pushing out of the piston 6 from the housing 2 in the direction of the contact head 4 is prevented.

[0040] According to the present embodiment, as shown in Figure 1A, the contact head 4 is designed as a separate element from the contact piston 6. For this purpose, the contact head 4 has a plug-in section 13, which is inserted into the section 7 of the piston 6. The plug-in section

[0041] 13 and the section 7 are in particular always identical and designed to match or be compatible with one another. In particular, the plug-in section 13 is pressed axially into the piston 6, so that the contact head 4 is held on the piston 6 by a press fit. Optionally, the contact head 4 is also welded, soldered or positively connected to the piston 6, for example by flanging or deformation. The two-part design of the piston with the separate contact head 4 and the piston 6 ensures easy adaptation of the spring contact pin to different boundary conditions and / or contact partners. In this way, contact heads 4 with different, in particular differently shaped, contact surfaces 5 can be provided and connected to the piston 6. The assembly of a selected contact head 4 with the piston 6 preferably takes place when the piston 6 is already mounted in the housing 2.Alternatively, assembly takes place before the piston 6 is mounted in the housing 2. In a system of spring contact pins or contact elements that has a plurality of pistons 6 and contact heads 4, the pistons 6, in particular, are of identical design and a plurality of different contact heads 4 are provided, so that the desired spring contact pin can be produced with little effort by combining a specific contact head 4 with one of the pistons 6. Alternatively or additionally, a plurality of preassembled pin assemblies are provided, each consisting of a piston 6 and a contact head 4 already attached to it, wherein the contact heads can be of identical or different design.

[0042] The spring contact pin 1 further comprises a spring element 14 in the form of a helical spring. The helical spring 14 is preloaded between the housing 2 and the contact element 3 in such a way that it forces the contact element 3 with the contact head 4 out of the housing 2 or forces the axial stop 12 against the cross-sectional taper 11 of the housing 2. For this purpose, the spring element 14 is supported with one end on a housing end 15 of the housing 2 facing away from the contact head 4. The other end of the spring element 14 is supported on the contact element 3, in particular on the piston 6. For this purpose, according to the present exemplary embodiment, the outer diameter of the spring element 14 is smaller than the inner diameter of the contact piston 6, so that the spring element 14 extends into the piston 6.In particular, the cross-sectional taper 11 forms an axial stop 16 for the spring element 14, so that the spring element 14 is axially supported on the cross-sectional taper 11 on the inside of the piston 6. In the unactuated or rebounded state, as shown in Figure 1B, the spring element 14 thus extends over almost the entire length of the housing 2 and over the entire length of section 8 of the piston 6.

[0043] Figure 1C shows an enlarged detailed view of the spring contact pin 1 in the region of the housing end 15. The spring element 14 preferably has two differing longitudinal sections. According to the present exemplary embodiment, the longitudinal section 14_1 located within the piston 6 in the unactuated state is designed to be resilient or elastically deformable. The longitudinal section 14_2 located outside the piston 6, in contrast, is designed to be rigid, so that it cannot deflect. This is shown by way of example in Figures 1A and C by the adjacent turns of the helical spring in the longitudinal section 14_2, while the turns in the longitudinal section 14_1 are axially spaced from one another and thus allow axial deflection.

[0044] Because the longitudinal section 14_2 of the spring element 14 exposed by the piston 6 is rigid, there is no movement or radial contact between the longitudinal section 14_2 and the inside of the housing 2 when the contact element 3 is compressed during a test process, and thus no friction and no wear. The compression takes place solely within the piston 6. This has the advantage that, on the one hand, the wear of the spring contact pin 1 is reduced overall and, particularly in the area of ​​the electrically conductive contact points between the piston 6 and the housing 2, wear is prevented by the spring element 14. During operation, only the piston 6 and the housing 2 rub against each other, which reduces overall wear and thus increases the service life of the spring contact pin 1.Because the spring element 14 extends into the piston 6 and is axially supported there, a particularly long guide surface is created between the piston 6 and the housing 2, ensuring precise guidance of the contact element 3 with low friction. The long contact surface also ensures a secure electrical connection between the housing 2 and the contact element 3.

[0045] Figure 1D shows the spring contact pin 1 in the compressed state, i.e. when the contact element 3 is compressed into the housing 2 against the force of the spring element 14. The spring travel is limited either by the spring element 14 itself or by the length of the piston 6, which abuts the housing end 15 of the housing 2. Due to the rigid design of the longitudinal section 14_2, this extends partially or largely into the piston 6, depending on how long the piston 6 is and how large the sliding travel is possible, so that the longitudinal section 14_1 is located completely within the piston and is compressed there, as shown in Figure 1B.

[0046] Figure 1E shows an enlarged view of the spring contact pin 1 in the area of ​​the housing end 15 in the compressed state. The piston 6 has an insertion bevel 17 for the spring element 14 at the free end of section 8. During compression, the spring element 14 is thus advantageously guided into the piston 6, so that snagging or jamming of the piston 6 on the spring element 14 or vice versa is reliably prevented. The advantageous design of the spring contact pin 1 results in the combination of two deep-drawn parts (piston 6 and housing 2) which, when inserted into one another, act as a sliding guide, enabling significantly narrower guide gaps because the practically achievable diameter tolerances are approximately 3 times better than with turned parts. This significantly increases the effective contact surfaces between the piston 6 and the housing 2, which reduces surface pressure and thus directly reduces frictional wear.The overall material usage is significantly reduced, with the weight of the contact element 3 to be moved being reduced, in particular, and material costs being lowered. The fact that the contact head 4 and the piston 6 are designed as separate elements also offers the advantage that the coating thicknesses of the two parts can be determined independently of each other, as can the coating materials and coating technologies. The base materials can also be selected and used independently of each other. This also enables unconventional manufacturing technologies, particularly for the contact head 4, and the associated realization of novel head shapes.

[0047] The remaining wear caused by the spring element 14 within the piston 6 is less disruptive there because it does not impair the electrical function of the spring contact pin 1, in particular the contact surfaces. Thus, while wear remains, it is separated from the functionally important zones or contact zones between the housing 2 and the piston 6. This advantageous design also prevents wear that occurs with conventional spring contact pins, in which the spring element is preloaded against the free end of the piston. With a conventional design, abrasion also occurs in the functionally important guide area of ​​the piston 6 and the housing 2 and remains there.Because the wear is now shifted into the piston 6 by the spring element 14 extending into the piston 6, abrasion also remains essentially within the piston 6 and does not reach the contact points between the piston 6 and the housing 2, or does so less quickly, thereby further increasing the service life of the spring contact pin 1. Furthermore, the rigid longitudinal section 14_2 of the spring element 14 ensures that fewer transverse forces act on the piston 6, thereby further increasing the service life of the spring contact pin by reducing frictional forces.

[0048] Advantageously, the piston 6 and the housing 2 have a coating to increase electrical conductivity and / or reduce wear. This coating may, for example, be a galvanic precious metal plating or something similar.

[0049] Figure 2 shows a second embodiment of the spring contact pin 1, which differs from the first embodiment in that the spring element 14 does not have a constant diameter, as in the previous embodiment. Instead, the diameter of the spring element 14 or the helical spring widens towards the housing end 15, so that the spring element 14 is wider at its end facing the housing end 15, as shown in Figure 2. This ensures a secure, in particular axially centered, contact of the spring element 14 on the housing end 15, even if the latter, as shown in the present embodiment, has a remaining opening 18, which is particularly due to manufacturing. Both the housing 2 and the piston 6 are advantageously designed as deep-drawn parts.This allows, in particular, the different cross-sections or diameters of the piston 6 in sections 7 and 8 to be advantageously realized. The housing 2 can also be manufactured cost-effectively and precisely. According to the first two exemplary embodiments, the housing end 15 is already formed by the deep-drawing process in such a way that it forms the axial stop for the spring element 14. The flange 10 is then produced to form the cross-sectional taper 9 at the opposite end.

[0050] According to an alternative embodiment, as shown in Figures 3A and 4B, the cross-sectional taper 9 is produced in the form of a step during the deep-drawing process. The housing end 15 is open or formed without a taper after the deep-drawing process, as shown in Figure 3A. Thus, the contact element 3 is now inserted axially from the side of the housing end 15, with section 7 first, as shown by an arrow 19 in Figure 3A. Subsequently or simultaneously, the spring element 14 is inserted or pushed into the housing 2 from the housing end 15. Only then is the housing end 15 plastically deformed, so that the cross-section of the housing 2 is tapered or reduced at the housing end 15, as shown in Figure 3B. For this purpose, the end is bent inwards, as indicated by arrows 20 in Figures 3A and B. In particular, this involves a flanging.The deformation is preferably located at the end of the casing or near the end, so that as little installation space as possible is lost. The piston 6 is then held in a captive, form-fitting manner by the spring element 14 in the housing 2. For final assembly, the contact head 4 is then mounted on the piston 6. If the contact head 4 has an outer diameter that is only as large as the outer diameter of the piston 6 in section 7, the contact head 4 can also be mounted on the piston 6 before the piston 6 is mounted in the housing 2 and pushed through the housing 2 together with the piston 6.

[0051] Figure 4 shows a further, fourth embodiment of the spring contact pin 1 in an enlarged longitudinal section. This embodiment differs from the previous embodiments in that the rigid longitudinal section 14_2 is not assigned to the end of the spring element 14, but is formed between two resilient longitudinal sections 14_1 and 14_2 - viewed in the longitudinal extension of the spring element 14. In the unactuated state of the spring contact pin 1, the rigid longitudinal section 14_2 lies in the region in which the spring element 14 penetrates the piston 6. As a result, the spring element 14 is stiffened in the transition region, preventing canting or tilting of the spring element when the piston 6 compresses and thus when pushed onto the spring element 14.Because the subsequent resilient longitudinal section 14_3, which leads to the housing end 15, is also compressible or elastically deformable, the spring travel is increased compared to the previous embodiment and the spring element 14 is adapted to the inner diameter of the housing 2.

[0052] Figure 5 shows a fifth embodiment of the spring contact pin 1, which differs from the previous embodiments in that the rigid longitudinal section 14_2, in the rebounded state or in the unactuated state of the spring contact pin 1, lies completely within section 8 of the piston 6. Thus, compared to the embodiment of Figure 1, the rigid longitudinal section and the resilient longitudinal section of the spring element 14 are interchanged. Preferably, the diameter of the spring element 14 increases in the resilient section, so that the spring element 14 rests radially against the inside of the housing 2 in the resilient region in order to be optimally guided there.

[0053] Preferably, at least in the embodiments of Figures 4 to 6, changes in the diameter of the spring element 14 are each realized by a conical transition length section. This reduces sudden mechanical stress in the spring element 14. Furthermore, the first contact point of the spring element 14 on the housing 2 is preferably placed axially further away from the piston guide. This shortens the wear area. Figure 6 shows a sixth embodiment of the spring contact pin 1, which differs from the preceding embodiments in that the spring element 14 does not have a rigid longitudinal section. However, as shown in the fifth embodiment, the spring element 14 has an enlarged diameter in the longitudinal section of the spring element 14, which is guided radially in the housing 2.The widening of the diameter is axially spaced from the piston 6, so that when the contact element 3 is compressed, further areas of the longitudinal section of the spring element 14 with a reduced diameter can initially penetrate into the piston 6.

[0054] Figure 7 shows a further embodiment of the spring contact pin 1, which differs from the previous embodiments in that the spring element 14 rests on the end of the piston 6 facing the housing end 15 and does not penetrate into it. For this purpose, the spring element 14 has a reduced diameter at its end facing the piston 6, so that only the end of the spring element 14 penetrates the piston 6, thereby centering the piston 6. The insertion bevel 17 of the piston 6, together with the coils of the helical spring, acts to center the spring element 14 and the piston 6.

[0055] Figure 8 shows an eighth embodiment of the spring contact pin 1, which differs from the previous embodiments in that the piston 6, from its end facing the housing end 15, has a reduced diameter, in particular a plastic deformation, similar to that of the housing end 15. The helical spring 14 has a constant diameter, and the inner diameter of the taper of the piston end is smaller than the inner diameter of the spring element 14 of the helical spring. As a result, the helical spring 14 is guided with its coils between the tapered end 21 and the inside of the housing 2, which also achieves centering. However, the piston 6 penetrates the spring element 14 and not the other way around, as in the embodiment of Figure 7, for example.

[0056] Figures 9A and B show a ninth embodiment of the spring contact pin 1, which corresponds to the embodiments of Figures 7 and 8 in that the spring element 14 is supported on the end of the piston 6 facing the housing end 15. In contrast to the previous embodiments, however, the spring element 14 is supported directly on the undeformed, flat end wall of the cylindrical section 8 of the piston 6, as shown in the detailed view of Figure 9B.

Claims

CLAIMS 1. Spring contact pin (1) for electrically conductive contact with a contact partner, with a sleeve-shaped housing (2) and with a contact element (3) mounted longitudinally displaceably in the housing (2), which has a piston (6) located at least partially in the housing (2) and a contact head (4) located outside the housing (2) with a contact surface (5) for contact with the contact partner, wherein a spring element (14), in particular a helical spring, is arranged in the housing (2) in such a way that the contact element (3) can spring into the housing (2), characterized in that the piston (6) is tubular as a hollow piston, and that the contact surface (5) of the contact head (4) is closed.

2. Spring contact pin according to claim 1, characterized in that the contact head (4) is designed as a solid body and has a plug-in section (13) which is inserted axially into the piston (6).

3. Spring contact pin according to one of the preceding claims, characterized in that the piston (6) is designed as a deep-drawn part.

4. Spring contact pin according to one of the preceding claims, characterized in that the plug-in section (13) for the electrical and mechanical connection to the piston (6) is held in the piston (6) in a force-fitting, form-fitting and / or material-fitting manner.

5. Spring contact pin according to claim 3, characterized in that the plug-in section (13) is held in the piston (6) by pressing, flanging, crimping, welding and / or fusing.

6. Spring contact pin according to one of the preceding claims, characterized in that the piston (6) has a cross-sectional taper (11) between its ends and that the spring element (14) extends into the piston (6) and is located on the Cross-sectional taper (11) on the one hand and axially supported at a housing end (15) on the other hand.

7. Spring contact pin according to one of the preceding claims, characterized in that the cross-sectional taper (11) of the piston (6) is arranged closer to the contact head (4) than to the end of the piston (6) facing the housing end (15), as seen in the axial extension of the piston (6).

8. Spring contact pin according to one of the preceding claims, characterized in that the spring element (14) has at least one rigid spring element section (14_2).

9. Spring contact pin according to one of the preceding claims, characterized in that the rigid spring element section (14_2) lies at least substantially between the piston (6) and the housing end (15).

10. Spring contact pin according to one of the preceding claims, characterized in that the rigid spring element section (14_2) has an outer diameter which is smaller than the inner diameter of the housing (2).

11. Spring contact pin according to one of the preceding claims, characterized in that the piston (6) has an insertion bevel (17) for the spring element (14) at its end facing the housing end (15).

12. Spring contact pin according to one of the preceding claims, characterized in that the housing end (15) is plastically deformed, in particular bent, to form an axial stop for the spring element (14).

13. Spring contact pin according to one of the preceding claims, characterized in that the housing (2) has, at its end facing away from the housing end (15), a cross-sectional taper (9) forming a step, wherein the step is designed as an axial stop (12) for the piston (6) which acts against the force of the spring element (14).

14. Spring contact pin according to the preceding claim, characterized in that the cross-sectional taper (9) of the housing (2) is produced by flanging or by a deep-drawing process.

15. Spring contact pin according to one of the preceding claims, characterized in that the length of the section of the piston (6) which lies at least in the housing (2) corresponds to the length of the housing (2) less a maximum permissible spring travel of the spring element (14) and less a predeterminable tolerance value.

16. Spring contact pin according to one of the preceding claims, characterized in that the end of the spring element (14) facing the housing end (15) is widened.

17. Spring contact pin according to one of the preceding claims, characterized in that the spring element (14) outside the piston (6) has a longitudinal section along which the outer diameter of the spring element (14) widens in the direction of the housing end (15), so that the spring element (14) outside the piston (6) rests against an inner side of the housing (2).

18. Spring contact pin according to one of the preceding claims, characterized in that the longitudinal section forms the rigid longitudinal section (14_2) of the spring element (14).

19. Spring contact pin according to one of the preceding claims, characterized in that the piston (6) has at its end facing the housing (2) a Cross-sectional tapering (21) on which the spring element (14) is supported.

0. Spring contact pin according to claim 19, characterized in that the The cross-sectional taper (21) forms a centering bevel for centering the spring element (14) between the piston (6) and the housing (2).

1. Spring contact pin according to one of the preceding claims, characterized in that the spring element (14) has a diameter reduction (22) at its end facing the piston (6) for centering the spring element (14) on the piston (6).

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