Patent Description:
In a spring-loaded connector having a tubular housing hosting a spring-loaded piston with a clip accommodated therein with a plurality of beams, it would be conceived that the clip is inserted into the tubular housing by pushing the beams of the clip. However, this process may damage the beams and reduce a reliability of the connector.

In addition, providing a piston assembly to allow insertion of the clip by pushing it via an end face opposite to the beams may require increased wall thickness to achieve the required press fit resistance. Such an increase of thickness leads to an increase of the pitch in a plug having several spring-loaded connectors.

<CIT> discloses a piston assembly according to the preamble of claim <NUM>.

An object of the disclosure is to provide a reliable compact piston assembly and a spring-loaded contact including the same.

The present disclosure further concerns a piston assembly for a spring-loaded contact, including:.

wherein the piston body has a through hole, the clip being in the through hole.

According to the above structure, as the piston assembly is made of separate parts (a piston body and a clip) and the piston body includes a through hole, the clip can be inserted into the through hole of the piston body through the first end, so that clip may not be damaged during assembling. In addition, the piston assembly may ensure a reliable contact with the conductive portion.

Advantageously, the piston body has a length representing <NUM>% to <NUM>% of the length of the piston assembly, preferably <NUM>% to <NUM>%, more preferably <NUM> to <NUM>%, most preferably <NUM> to <NUM>%. This feature contributes to reducing a length or a height of the spring-loaded contact.

Advantageously, the first end has a contacting surface to contact an external part directly. Consequently, no protruding cap may be provided to the piston assembly and the length of the piston body may represent <NUM>% of the length of the piston assembly in the case the clip protrudes from the piston body to <NUM>% in the case the clip is fully embedded in the piston body. Such a piston assembly shows a very limited length or height.

Advantageously, the piston assembly may have a cap or seal at least partially received in the through holes and closing the first end. Such an embodiment is relevant in the case of water or dust-proof application, to avoid water or dust from reaching the through hole. For example, the cap may be fully embedded in the piston body or may slightly protrude from the first end of the second body. Preferably, the cap has a length representing <NUM>% or less, preferably <NUM>% or less, again preferably <NUM>% or less and most preferably <NUM> or <NUM>% or less of the length of the piston assembly.

Advantageously, the piston body has a second end opposite the first end and wherein the clip protrudes partially from the second end. Preferably, the clip has a length representing <NUM>% or less, preferably <NUM>% or less, again preferably <NUM>% or less and most preferably <NUM> or <NUM>% or less of the length of the piston assembly. Such a protruding clip may enhance the electrical conduction and reduce the electrical disconnections in case of shocks or vibrations.

Advantageously, the clip is press-fitted in the through hole which allows a simple assembling method and a reliable fixing of the clip.

wherein the base end is located in the through hole, on the side of the first end of the piston body.

According to this structure, damages to the flexible contacting end or clipping portion may be prevented when pushing the base end to insert the clip into the through hole of the piston body.

Advantageously, the clipping portion extends from the base end in a direction opposite to the first end of the piston body. This allows to produce a more reliable and easier to assemble piston assembly. The clipping portion may have beams possibly flexed inwardly, i.e., toward a center of the though hole.

Advantageously, the base end has a clip wall arranged to withstand a press fit force applied to the clip to insert the clip into the through hole. This may contribute to an easier assembling of the piston assembly while preventing damages to the clip.

Advantageously, the clip defines a through cavity i.e., is hollow and has two opposite and open ends. Such a clip may be cheaper and easier to handle during the assembling process.

Advantageously, the piston body includes a piston groove to accommodate at least part of a coil spring of the spring-loaded contact. This may allow to use a longer coil spring, thus ensuring a reliable current transmission despite shocks and vibrations. The piston groove may be open in the direction of the second end and/or opposite to the first end of the piston body.

This piston assembly may include any advantageous feature described above.

The present disclosure further concerns a spring-loaded contact, including:.

Such a spring-loaded contact may transmit an electrical current with no or few disconnections despite shocks and vibrations and is easy to manufacture and to assemble.

Advantageously, the conductive portion includes a pin portion for mating with the clip. For example, the pin portion is received partially in the clip, in a resting position of the piston assembly, i.e., when no external pressure is applied on the piston assembly. For example, the pin is introduced in the clip and in the through hole through the second end of the piston body. The pin portion and the piston assembly may be preferably configured so that the pin portion always contact the clip, whatever the position of the piston assembly.

Advantageously, the pin portion and the piston assembly are configured so that the pin portion is mainly or fully located in the piston assembly in a compressing position of the spring-loaded contact. This allows to prevent any damage to the external part that may be fixed to the piston assembly. For example, the pin portion does not protrude from the first end of the piston assembly, even in a compressing position of the piston assembly.

Advantageously, the conductive portion includes a base portion for connecting another external part such as an electronic or electric circuit. The base portion may be fixed at least partially within the housing. For example, when the base portion is connected to the other external part, an electrical current may be transmitted from the external part to the other external part.

Advantageously, the base portion has a base groove to accommodate at least part of the coil spring of the spring-loaded contact. This may allow to use a longer coil spring, thus reducing or canceling electrical disconnections despite shocks and vibrations.

Advantageously, a coil spring is located between the base portion and the piston body. The coil spring may maintain the piston assembly in a resting position, i.e., at one extremity of the housing opposite to the base portion of the conductive portion.

Advantageously, the housing includes an external bulge or rib. Such an external bulge allows to manipulate the housing and simplifies the assembling process of the spring-loaded contact.

wherein the piston body and the clip define a pass-through receiving section for the conductive portion.

This piston assembly may also have any of the advantageous features disclosed above. This piston assembly has no cap which allows to reduce the length or the height of the piston assembly.

The spring-loaded contact may have no protruding cap which allows to reduce the length or the height of the spring-loaded contact.

The present disclosure finally concerns a method to manufacture a piston assembly, the method comprising:.

This method allows to efficiently manufacture a piston assembly. The piston assembly may be as described above.

Other features and advantages of the present invention will appear more clearly from the following detailed description of particular non-limiting examples of the invention, illustrated by the appended drawings where:.

With reference to <FIG>, a piston assembly <NUM> may have a piston body <NUM>. The clip <NUM> is inserted inside the piston body <NUM>. The piston body <NUM> may be provided with a tubular wall <NUM> having a through hole <NUM> and a flange <NUM> formed on the outer surface of the tubular wall <NUM>. The flange <NUM> may have a greater diameter than the diameter of the tubular wall <NUM>.

In the embodiment of <FIG>, the tubular wall <NUM> has a greater diameter in a front portion (or upper portion) and a smaller diameter in a rear portion (or bottom portion). Alternatively, the tubular wall may have a constant diameter at both sides of the flange <NUM>. In addition, the optional flange <NUM> may be replaced by a groove or by attaching means such as protrusions extending perpendicularly from the longitudinal axis of the piston body <NUM>.

A contacting surface <NUM> may be provided, for example around the through hole <NUM> and/or on a front-end portion of the piston body <NUM>. The contacting surface <NUM> may allow to contact an external part, for example an electric or electronic circuit. The contacting surface <NUM> may have a curved surface, as visible in <FIG> or alternatively a flat surface.

The front surface or front extremity of the piston body <NUM> may be a first end <NUM> of the piston body and the rear surface or rear extremity of the piston body <NUM> may be a second end <NUM> of the piston body <NUM>. In <FIG>, no cap is provided in the through hole <NUM> and only the clip <NUM> may slightly protrude from the second end <NUM> of the piston body <NUM>. The length of the piston body <NUM> (i.e., the dimension of the piston body on the longitudinal axis of the piston body <NUM>) may thus be <NUM>, <NUM> or <NUM>% of the length of the piston assembly <NUM>.

Referring to <FIG>, the clip <NUM> may have a base end <NUM> for example in the form of a clip wall <NUM>, optionally tubular, and a clipping portion <NUM> positioned opposite to the contacting surface <NUM>. The base end <NUM> may be provided with an end face <NUM>. The base end <NUM> may have an outer diameter substantially identical to the inner diameter of the through hole <NUM> so that the clip <NUM> can be pushed and inserted into the through hole <NUM> (press fit assembly).

The clipping portion <NUM> may comprise a plurality of flexible beams <NUM> in a form of cantilever extending from the base end <NUM>, for example four beams as visible in <FIG> or alternatively, two, three or five beams. For a person skilled in the art, it is understood that a different number of beams <NUM> can be used as long as they can hold a part of a conductive portion in any position of the clip <NUM>.

Each beam <NUM> may be slightly bent radially inwardly and/or the diameter of the clipping portion <NUM> may become smaller toward the tip end. Finally, each beam <NUM> may have a tab <NUM> in an end portion of the beam <NUM>, the tab may have a width greater than a final width or any width of the beam <NUM>, as visible in <FIG>. The tabs <NUM> may reduce or cancel any hanging of the clips <NUM> before assembling the clips <NUM> in the piston bodies <NUM>.

The clip <NUM> may be inserted into the through hole <NUM> of the piston body <NUM>, preferably through the first end <NUM> and along a front-to-rear direction or direction D in <FIG>, for example along a longitudinal axis Ax of the piston body <NUM> and/or the clip <NUM>. The clip <NUM> may thus be fixed in the through hole <NUM>, preferably by press-fitting. Alternatively, ultrasonic welding may be considered.

The advantage of inserting the clip <NUM> in this direction is that the beams <NUM> of the clip <NUM> may contact a conductive portion of the spring-loaded contact deeper into the spring-loaded contact <NUM>, thus providing a reliable contact in a shorter height (a length along the front-rear direction in the drawings). In addition, inserting and pushing the clip <NUM> from the side opposite to the conductive portion of the spring-loaded contact <NUM> provides the ability to push on the end face <NUM>, avoiding any stress on the beams <NUM>.

In <FIG>, the clip <NUM> may be open at both the rear ends, to receive a conductive portion, and at the front end, which may allow the clip <NUM> to be transported and handled more easily. In addition, an open front end may simplify the manufacturing of the clip <NUM>. For example, the clip <NUM> may be obtained by cutting and rolling a flat sheet of metal.

Alternatively, the front-end portion of the clip may be closed by a clip closing portion (not shown), which may increase the surface area of the contacting surface <NUM> or at least prevent any ingress of liquid or dust in the clip <NUM>.

The reverse insertion of the pin (i.e., in the rear direction or direction D) has been made possible by the assembly construction. If the piston body <NUM> has no through hole <NUM>, the clip <NUM> cannot be inserted without damaging the beams <NUM>. The present embodiment allows an assembling method involving a step of pushing on the base end <NUM> (i.e., the end face <NUM>) of the clip <NUM>.

The piston body <NUM> can be typically machined from brass, phosphor-bronze, beryllium-copper, other copper alloy or other conductive metals/alloys, including nickel-silver alloys. The clip <NUM> can be manufactured from a copper alloy, typically beryllium-copper, beryllium-nickel or other high strength conductive copper alloy. The parts are typically post-plated with any one of a variety of coatings, typically a gold plating and/or silver plating, for the purpose of enhancing electrical contact and improving wear and corrosion resistance of the piston assembly <NUM>.

Now with reference to <FIG>, the spring-loaded contact <NUM> has a guiding cylinder or housing <NUM> and the piston assembly <NUM> may be accommodated in the housing <NUM>. The housing <NUM>, piston body <NUM> and clip <NUM> may be designed to align concentrically with each other, i.e. along a longitudinal axis Ax of the piston assembly <NUM> and of the spring-loaded contact <NUM>.

The piston assembly <NUM> is configured to be movable along the longitudinal axis Ax of the housing <NUM> and of the spring-loaded contact <NUM>. In the housing <NUM>, a coil spring <NUM> and a conductive rod <NUM>, as an example of a conductive portion, may be provided, the configurations and functions of which will be described later. The housing <NUM> may thus guide a movement of the piston assembly <NUM> with regard to the conductive rod <NUM> and protect the interface between the conductive rod <NUM> and the clip <NUM>.

<FIG> shows the piston assembly <NUM> disposed in the housing <NUM> such that the flange <NUM> is positioned within the housing <NUM> and a front part of the piston assembly <NUM>, in particular the first end <NUM>, is protruding from an end wall <NUM> of the housing <NUM>. The flange <NUM> may be pushed by way of the coil spring <NUM> so that the flange <NUM> abuts inside the end wall <NUM> in a resting position, for example in a direction opposite to the direction D, i.e., in the front direction in <FIG> and <FIG>. The piston assembly <NUM> can be pushed into the housing <NUM> (i.e., in the rear direction or in direction D) to compress the coil spring <NUM> when it contacts an external component and/or when it is submitted to pressure in the rear direction.

The clipping portion <NUM> of the clip <NUM> can hold at least a part of the conductive rod <NUM> which may form or include a conductive portion. The clip <NUM> and the piston body <NUM> may thus define a receiving section for the conductive portion. The receiving section may be open at both ends to define a pass-through receiving section or may be closed by a cap, as presented later. The conductive rod <NUM> may have a base end <NUM> and a pin portion <NUM> extending vertically from the inner surface of the base end <NUM>. The clipping portion <NUM> is configured to contact a contacting area of the pin portion <NUM>. A front extremity of the pin portion <NUM> may be beveled, conical or sharp in order to facilitate an insertion of the clip <NUM> on the pin portion <NUM>, for example without any damage to the beams <NUM>.

The contacting area of the pin portion <NUM> can form <NUM>% the length of the pin portion <NUM> or less, <NUM>% or less of this length or <NUM>% of this length and preferably at least <NUM>%, in a resting position of the spring-loaded contact <NUM> shown in <FIG>. The length of the contacting area may depend on the length of the stroke of the piston assembly <NUM>.

In the embodiment of <FIG>, the circular base end <NUM> can be mechanically fixed to the inside of the housing <NUM> (by press fit assembly, or ultrasonic welding).

Preferably, the total length of the pin portion <NUM> is chosen so that the pin portion <NUM> does not protrude out of the piston assembly <NUM> in a compressed position, when the coil spring <NUM> is in a maximum compression state and/or has its shortest length. For example, the length of the pin portion <NUM> may be equal to or smaller than the length of the pin <NUM> or of the through hole <NUM>.

The housing <NUM> may have an external bulge or circumferential rib <NUM> in order to simplify manipulation of the housing before and during the assembling process of the spring-loaded contact <NUM>.

<FIG> shows another spring-loaded contact <NUM> according to the present invention. This spring-loaded contact <NUM> is similar to the spring-loaded contact <NUM> described with reference to <FIG> with the exception of the piston body <NUM> and of the conductive rod <NUM>.

The flange <NUM> of the piston body <NUM> may include a piston groove <NUM> open toward the rear direction and configured to receive a front extremity of the coil spring <NUM>. The base end <NUM> may include a base groove <NUM> open toward the front direction and configured to receive a rear extremity of the coil spring <NUM>. The piston groove <NUM> and the base groove <NUM> allow to use a longer coil spring <NUM>, which may provide a better resistance to shock and vibrations to the spring-loaded contact <NUM>. Circumferential portions of the base end <NUM> and/or of the flange <NUM>, for example nearby the base groove <NUM> and the piston groove <NUM> may also acts as stopping portions to prevent any contact between the clip <NUM> and the base end <NUM>.

<FIG> represents another spring-loaded contact <NUM>, identical to the spring-loaded contact <NUM> with the following differences in the piston assembly <NUM>. The through hole <NUM> may include a front portion 177f having a diameter larger than a core portion 177c. The clip <NUM> is located in the core portion 177c, as previously described. A cap <NUM> is introduced in the front portion 177f to close the through hole <NUM> at the first end <NUM> of the piston assembly <NUM>.

The cap <NUM> may protrude from the first end <NUM> of the piston body <NUM> in <FIG> by a convex front surface <NUM>. However, the front surface may also be flat or concave, which may allow to preserve a contacting surface of the piston body for a direct connection of the external part to the piston body (not shown).

The pin portion <NUM> of the conductive rod <NUM> may be shorter than the pin portion <NUM> of <FIG> and <FIG>. Alternatively or in combination, the clip <NUM> may be shorter than the clip <NUM> of <FIG>. In any case, the clip <NUM> must contact the pin portion <NUM> in any position of the piston body <NUM> without pushing the cap <NUM> out of the through hole <NUM>.

While not being linked to the cap <NUM> and piston assembly <NUM>, the housing <NUM> may include an external bulge or circumferential rib <NUM> located in a mid-portion of the external wall of the housing <NUM>.

The cap <NUM> may be made of polymer such as Kapton (polyimide) or in metal, similarly to the clip <NUM> and the piston body <NUM>, as described above. If a non-conducting polymer is used, the cap <NUM> preferably has a flat or a concave front surface to preserve the contacting surface <NUM> of the piston body <NUM>.

Finally, regarding dimensions, the spring-loaded contact according to the present disclosure may have any dimension authorized by the specific external parts to be connected. For example, the clip <NUM>, <NUM> may have a length of <NUM> to <NUM>, for example <NUM> or <NUM>. The total length of a spring-loaded contact <NUM>, <NUM>, <NUM> may be <NUM> to <NUM>, for example <NUM> to <NUM> and the largest diameter may be <NUM> to <NUM>, for example <NUM> or <NUM>. The largest diameter of the piston body <NUM>, <NUM> may be <NUM> to <NUM>, for example <NUM> or <NUM>. The spring-loaded contact according to the present disclosure may transmit a current of <NUM> to <NUM> A, for example <NUM> to <NUM> A, with no or very few electrical disconnections.

Claim 1:
A piston assembly (<NUM>, <NUM>, <NUM>) for a spring-loaded contact, including
- a piston body (<NUM>, <NUM>, <NUM>) to be received into a housing of the spring-loaded contact and having a first end (<NUM>, <NUM>) to be connected directly or indirectly with an external part,
- a clip · (<NUM>, <NUM>) to mate with a conductive portion of the spring-loaded contact, the piston assembly being characterised in that the piston body has a through hole (<NUM>, <NUM>), the clip being in the through hole.