Stem cap to ensure secure attachment of electrical busbars and a watertight seal

Abstract

A stem plug (10) for connecting a first busbar (4) and a second busbar (5) in an electrical / electronic housing (66) and for sealing an opening (60), the stem plug comprising a disc-shaped body (1) having a first axis, a stem (2) extending from a first end (21) adjacent to the body to a second end (22), the stem being extended by a finger (3) from the second end of the stem (22) to a free end (32), the finger being formed as a cylinder with a round cross-section, the diameter of which is less than a transverse dimension of the second end of the stem, forming a shoulder (7) at the second end of the stem, adapted to push, directly or indirectly, the first electrical busbar against the second electrical busbar. (See diagram: Fig. 3)

Description

Title of the invention: Stem plug for securing and sealing electrical busbars

[0001] The present invention generally relates to a stem plug for ensuring the fixing of an electrical busbar and sealing with respect to an orifice.

[0002] The present invention also relates to an electrical and / or electronic housing comprising a connection to be made between two busbars and a stem plug to ensure the connection between the two busbars and to form a seal with respect to an opening in the wall of the housing.

[0003] We are particularly interested here in electrical and / or electronic boxes in which a significant amount of electrical power passes, which requires the installation of conductors called busbars.

[0004] A busbar is a metal bar, preferably flat, made for example of aluminium or copper.

[0005] In an electrical and / or electronic enclosure, to ensure the electrical power path between the outside of the enclosure and the inside of the enclosure, a first busbar is used which passes through the wall of the enclosure and which is configured to be coupled to another element outside the enclosure, and a second electrical busbar is used internal to the enclosure.

[0006] In this configuration, it is necessary to connect the first busbar to the second busbar inside the housing, in an area of ​​the housing where access from the outside can be provided via holes made on the wall of the housing.

[0007] According to a known solution, there is a hole in each of the first and second busbars, and a screw passes through both holes. This screw is tightened by a socket of a screwdriver located outside the housing. The socket, through a specific opening, engages with and turns the screw in the area of ​​the busbar holes inside the housing. The specific opening for the socket must then be hermetically sealed with a plug.

[0008] A large opening for the screwdriver socket must therefore be provided. Furthermore, there are often at least two power supply routes to be provided, and consequently, the housing wall must have at least two large openings for the screwdriver socket.

[0009] In summary, the assembly of the first and second bus bars requires two parts (screw and cap) and requires two operations, i.e. screwing and installing the respective cap.

[0010] In this context, a need arose to propose a solution that was less expensive in terms of equipment and faster in terms of process time.

[0011] To this end, a stem plug is proposed to provide a connection between a first busbar and a second busbar in an electrical / electronic housing and to ensure the sealing of an opening made in a wall of said housing, the stem plug comprising: a disc-shaped body having a first axis, a rod (2) extending, parallel to the first axis, from a first end (21) adjacent to the body to a second end (22), the rod being extended by a finger (3) extending, as an extension of the rod, from the second end of the rod to a free end, the finger being formed essentially as a cylinder of round or polygonal section, of diameter less than at least one transverse dimension of the second end of the rod, thus forming a shoulder at the level of the second end of the rod, said shoulder being able to push, directly or indirectly, the first busbar against the second busbar.

[0012] Thanks to these arrangements, it is unnecessary to use a screwdriver-type tool to screw the two busbars together. Furthermore, a single part performs two functions: firstly, the electrical connection between the two busbars, and secondly, a watertight seal for the access port to the busbar connection.

[0013] It is noted that preferably the rod and the body can be coaxial, that is to say, share the same axis. However, it is not impossible for the rod not to be placed at the center of the disk.

[0014] Note that the disc shape of the body does not exclude the presence of a flat surface, as will be seen at the end of the description.

[0015] The term "ensuring a connection" must be understood to mean, at a minimum, an electrical contact. Consequently, there must be a minimum contact pressure, and there may even be a strong connection with immobilization thanks to the finger that passes through the holes and prevents any substantial relative movement of one busbar with respect to the other.

[0016] A busbar is an electrical busbar that allows the flow of a current with a high amperage. The busbar is a flat, elongated piece, generally rectangular in cross-section. The busbar is made, for example, of aluminum or copper, or alloys of these metals. Such a busbar is formed as a metal strip with a hole at the point of its electrical connection to another component.

[0017] Before the insertion of the stem plug, the two respective end portions of the busbars are in a slightly cantilevered configuration; the insertion of the finger and the push of the stem cause the two busbars to flex inwards towards the housing; the resilience of the second busbar may be greater than that of the first busbar or The second busbar may have a limited travel due to another element. Consequently, the shoulder exerts mechanical pressure that ensures close electrical contact between the two busbars.

[0018] Advantageously, as will be seen later, in the housing wall, the diameter of the orifice required for the placement of the proposed stem plug is smaller than the diameter required for the passage of the screwdriver socket.

[0019] According to one embodiment, the free end of the finger has a rounded, chamfered or conical tip.

[0020] Wherefore, the insertion of the rod and the finger into the holes is facilitated, even if the alignment is not perfect. Advantageously, the insertion of the finger recenters the two holes and realigns the positions of the two end portions of the busbar.

[0021] According to one embodiment, the stem cap is made of synthetic plastic material, based on polymer such as polyamide, polyethylene, or any other polymer suitable for the mechanical strength and electrical insulation requirements for this part.

[0022] According to one embodiment, the body includes a peripheral border with clipping lugs and a support collar.

[0023] The tabs retract when a user pushes the stem-operated cap towards the inside of the electrical enclosure. The tabs return to their rest position after passing through the thickness of the wall edge and then anchor themselves there, preventing the cap from moving backward.

[0024] According to one embodiment, at the end of the rod, an elastic pressure device is provided, configured to clamp together at least the first and second busbars.

[0025] The elastic pressure device can typically be a plastic pin, or a plastic elastic clamp.

[0026] According to one embodiment, the pressurization device comprises two tabs which embrace the two busbars, and which each have an inclined distal portion capable of causing the device to spread apart simultaneously with the pushing in of the stem plug, before they return to a closed position in contact with the first and second busbars, after passing beyond the second busbar.

[0027] According to one embodiment, a spring and a thrust washer are provided, the spring being interposed between the shoulder and the thrust washer, the thrust washer being configured to press on the first busbar.

[0028] This results in a pressurization with a well-calibrated prestress.

[0029] According to one embodiment, the body includes an annular groove open radially outwards in which an O-ring is disposed.

[0030] This provides effective sealing at the interface between the body of the cap and the opening in the housing wall.

[0031] According to one embodiment, the body is provided on its outer peripheral edge with a screw thread configured to cooperate with a complementary screw thread provided in the orifice.

[0032] This results in well-calibrated pressure and good value for money. It should be noted that the screwing function remains compatible with the presence of an O-ring.

[0033] According to one embodiment, the finger is equipped with a fir-tree pin. Advantageously, the teeth of the fir-tree pin are anchored behind the second busbar. This provides a sandwich assembly between the shoulder and at least one pair of teeth of the fir-tree pin. This solution offers excellent value for money.

[0034] The present invention also relates to an electrical / electronic housing comprising at least a first busbar with a first hole, a second busbar with a second hole, the first and second holes being substantially coaxial, a housing with at least one orifice, preferably round, located opposite the first and second holes, and a stem plug as shown and defined above, the finger being inserted into the first hole and into the second hole, the shoulder pressing directly or indirectly the first busbar against the second busbar, and the body hermetically sealing the orifice.

[0035] According to one embodiment, the orifice has an orifice diameter at most equal to three times the diameter of the finger.

[0036] This allows a significant reduction in the diameter of the holes, and a gain in size and weight of the electronic housing.

[0037] We can typically have the diameter of the finger D3 = 6 mm.

[0038] The orifice diameter D6 can typically be between 12 and 14 mm, preferably less than 18 mm, whereas a diameter of at least 20 mm is generally required to fit a screwdriver socket capable of handling an M6 screw with a hexagonal head.

[0039] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig. 1] illustrates in cross-section a first example of the realization of a stem plug ensuring the connection between two busbars and a seal at the level of the housing wall; - [Fig.2] illustrates in profile view the stemmed stopper of [Fig.1]; - [Fig.3] illustrates in cross-section a second example of the realization of a stem cap ensuring the connection between two busbars and a seal at the level of the housing wall, with a screw-on cap function; - [Fig. 4] illustrates in cross-section a third example of the realization of a stem cap ensuring the connection between two busbars and a seal at the level of the housing wall, with a finger in the shape of a Christmas tree pawn; - [Fig. 5] illustrates in cross-section a fourth example of the realization of a stem plug ensuring the connection between two busbars and a seal at the level of the housing wall, with a pressure spring and a support washer; - [Fig. 6] illustrates in cross-section a fifth example of the realization of a stem cap ensuring the connection between two busbars and a seal at the level of the housing wall, with an elastic clip pin; - [Fig.7] illustrates in perspective view the stem stopper of [Fig.1]; - [Fig.8] illustrates a top view of part of an electrical box power in an area where two pairs of busbars are connected together by means of two plugs formed according to the present invention; - [Fig.9] illustrates in a top view a particular example of an area where two Pairs of busbars are connected together by means of two plugs formed according to the fifth embodiment.

[0040] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0041] Figure 8 shows a portion of an electrical / electronic housing 66 in which carries electrical power in the form of significant currents. Here in the illustrated example, we have two electrical paths, for example a positive path VI and a negative path V2.

[0042] One or more electrical / electronic boxes of this type can be found in an electric or hybrid vehicle.

[0043] The housing wall is marked 6. The housing can be made of aluminum alloy or even of high-performance plastic material. The structural envelope of the housing is called the casing.

[0044] The first electrical track VI includes a first internal busbar 81 intended to be connected to a second busbar 83 which passes through the wall 6 in a connector element 65.

[0045] The second electrical channel V2 includes a first internal busbar 82 intended to be connected to a second busbar 84 which passes through the wall 6 in the connector element 65.

[0046] The second electrical track V2 illustrates a configuration where the end portions of the busbars to be connected have axes that are not aligned, whereas the axes of the busbars of the first track V1 are aligned.

[0047] In [Fig.8], a stemmed plug according to the invention is inserted into the access hole corresponding to the first electrical channel, whereas it is not present in the access port 60 corresponding to the second electrical channel.

[0048] In [Fig. 1], a first busbar 4 and a second busbar 5 are shown, corresponding, for example, respectively, to the first busbar 81 and the second busbar 83 discussed above in connection with [Fig. 8]. The first and second busbars are shown in profile, and their respective thicknesses E4 and E5 are visible. Each end of the busbar to be assembled has a hole. More precisely, the first busbar 4 has a first hole 41 and the second busbar 5 has a second hole 52.

[0049] The first hole 41 and the second hole 52 each have a diameter of 6 to 7 mm in the typical example shown.

[0050] The first busbar 4 is the busbar closest to the outside, that is, the one first encountered by the stem of the cap. Depending on the configuration, this may be either the inner or outer busbar.

[0051] The second busbar 5 is the busbar furthest from the outside, that is, the one that is encountered second by the stem of the cap. It can be either the inner or the outer busbar.

[0052] The second busbar 5 can be backed against a stop or its bending movement when pushed in reaction to an insertion of the rod is limited by a stop element or an elastic limit of stroke.

[0053] The width L4 is generally between 10 mm and 20 mm. The thicknesses E4 and E5 are generally between 2 mm and 5 mm.

[0054] Figure 1 shows a cross-section of the wall 6 of the housing at the location of the orifice 60. It should be noted that the casting of the housing provides a rim of the orifice 64 that is thicker than the wall in its main section.

[0055] The orifice 60 is a round orifice with an internal diameter D6. The axis of the orifice, called the first axis, is denoted A. D6 is generally between 12 mm and 20 mm. Preferably, D6 is less than 18 mm.

[0056] Turning to figures 1, 2 and 7, the proposed stem cap, identified as 10, comprises a disc-shaped body 1 which is centered on the first axis A.

[0057] The dimension of the body along the axis A is noted Ll, it can be between 2 mm and 5 mm for example.

[0058] The body 1 includes an annular groove 17 open radially outwards in which an O-ring 16 is disposed.

[0059] The body 1 includes a peripheral border with clipping lugs 9 and a support collar 8.

[0060] When the stemmed plug 10 is inserted into its position, i.e., from left to right in the figures, the lugs 9 bend as they pass the rim of the orifice 64, and the insertion movement continues, with the plug advancing until the collar 8 comes into contact with the outside of the rim of the orifice 64. The lugs 9 have then passed the On the opposite side of the orifice rim, they elastically return to their resting shape and thus lock the position of the plug body 1 relative to the wall 6.

[0061] The stem cap 10 includes a stem 2 which extends from a first end 21 adjacent to the body 1 to a second end 22.

[0062] The rod 2 extends parallel to A, here the rod and the body are coaxial.

[0063] The dimension of the rod along axis A is denoted L2; it can be between 10 mm and 40 mm for example.

[0064] In the illustrated example, the rod 2 has a round cross-section, but it could have a polygonal cross-section. The diameter of the rod, denoted D2, can in practice be between 8 mm and 10 mm.

[0065] The stem is extended by a finger 3 which extends from the second end of the stem 22 to a free end 32 of the finger.

[0066] The diameter of the finger, noted D3, can in practice be between 5 mm and 6 mm.

[0067] The dimension of the finger along axis A is denoted L3, we will see that this length depends strongly on the embodiment examples presented in the remainder of this disclosure.

[0068] Of course, the dimensions stated above must be adapted according to the diameter of the holes drilled in the busbars.

[0069] The free end of the finger 32 has a rounded, chamfered or conical tip to facilitate the insertion of the finger into the first and second holes 41,52.

[0070] In the illustrated example, finger 3 has a round cross-section, but it could have a polygonal cross-section.

[0071] The finger 3 has a diameter less than at least one transverse dimension of the second end 22 of the rod 2, which forms a shoulder 7 at the second end of the rod.

[0072] In the first embodiment illustrated in Figures 1, 2, and 7, the stem plug 10 pushes against the two busbars, each of which exhibits a certain degree of elasticity. More specifically, before the stem and its finger are inserted into the holes in the busbars, the busbars are at rest in a position closer to the orifice and the wall than after the stem plug is inserted. Furthermore, the second busbar 5 has higher resilience than the first busbar 4.

[0073] Consequently, when the stem plug 10 is inserted, the shoulder 7 pushes the two busbars. The first busbar 4 being more flexible than the second, this causes positive pressure contact between the first busbar 4 and the second busbar 5.

[0074] The end of the finger 32 may protrude from the hole of the second busbar, i.e. go beyond the thickness E5. Alternatively, the end of the finger 32 may remain below it; it is not necessary for it to protrude in the first embodiment.

[0075] The stem cap 10 is made of synthetic plastic material, based on a polymer such as polyamide, polyethylene, or any other polymer suitable for the mechanical strength and electrical insulation requirements of this part. The material in question may be fiber-reinforced.

[0076] In a second embodiment illustrated in [Fig. 3], a screwing function is provided for the body of the cap relative to the thick rim 64' of the orifice 60 in the wall. For this purpose, a helical thread is provided on the radially external peripheral rim of the body of the cap, which cooperates with opposing forms: either a complementary helical thread in the orifice, or simple lugs formed in the wall directed towards the axis of the rim 64'. The thread pitch can be either a quarter turn or a half turn to achieve the necessary screwing.

[0077] A kinematic of the bayonet movement type is also not excluded.

[0078] It is noted that the O-ring 16 is placed on the inner side relative to the helical thread.

[0079] It is noted that in this configuration, it is not necessary to have lugs or other clipping elements, it is the screwing function which ensures the final insertion movement and the mechanical retention of the body of the cap in the orifice 60.

[0080] It should be understood that everything not specifically commented on in the second embodiment example should be considered identical or similar to what was presented for the first embodiment example.

[0081] In a third embodiment illustrated in [Fig. 4], a fir tree pin 33 is provided at the end of the finger. In this configuration, the body of the plug is identical to that shown for the first embodiment. However, the end of the finger differs because it must necessarily penetrate beyond the thickness of the second busbar with the harpoon shapes of the fir tree pin which brace against the inner side.

[0082] The fir-tree pin 33 comprises a plurality of teeth 37 arranged axially one behind the other so that the gripping function can adapt to several thicknesses. At least one of these teeth 37 is anchored behind the second busbar.

[0083] The length L3 can typically be between 10 millimeters and 20 millimeters.

[0084] It must be understood that everything not specifically commented on in the third embodiment example should be considered identical or similar to what has been presented for the other embodiment examples already commented on.

[0085] In a fourth embodiment illustrated in [Fig.5], a spring pressure system is provided.

[0086] In this configuration, the body of the cap is identical to that shown in the first embodiment. However, the length of the stem, L20, is less than L2. To compensate, the length of the finger is greater.

[0087] A spring 34 and a support washer 35 are provided. The free end of the finger is provided with at least one hook 36.

[0088] The spring 34 is a helical metal spring operating in compression; it is mounted around the finger. The spring is interposed between the shoulder 7' and the thrust washer 35. The thrust washer 35 rests on the first busbar 4 around the hole 41; it acts as the shoulder already seen in the first and second embodiments. The thrust washer 35 is a metal washer, very common and inexpensive, just like the spring 34. The spring 34 and thrust washer 35 are pre-assembled and cleverly held in place by the hooks 36 before assembly onto the busbars.

[0089] The support pressure is well calibrated, it remains stable over time and in life, it is defined by the stiffness of the spring.

[0090] It is noted that the shoulder 7 of the rod provides indirect support in relation to the first busbar 4, which justifies the generic expression "being able to come and push directly or indirectly the first busbar 4 against the second busbar".

[0091] Here too, the end of the finger penetrates beyond the thickness of the second and a hook / harpoon 36 is provided which braces itself on the inner side behind the hole 52.

[0092] It should be understood that everything not specifically commented on in the fourth embodiment example should be considered identical or similar to what has been presented for the other embodiment examples already commented on.

[0093] In a fifth embodiment illustrated in [Fig.6], a pressure clip 12 is provided.

[0094] The elastic pressure device can typically be a plastic pin, or a plastic elastic clamp.

[0095] According to the illustrated embodiment, the pressure-setting device comprises a base 19 fixed in a groove 74 provided between the rod and the finger. From this base extend two elastic tabs 15 which embrace the two busbars.

[0096] Each leg 15 includes a distal portion 13 inclined with respect to the axis A (flared) suitable for causing the device to spread apart simultaneously with the insertion of the stem plug 10.

[0097] When the legs return to their closed position after the passage of the second bus-bar, the angled portion 14 comes to rest behind the second bus-bar 5.

[0098] Generally any elastic pressure device configured to clamp together at least the first and second busbars can be suitable.

[0099] This elastic clamp configuration is particularly suitable for the case where the axes of the busbars to be connected are aligned.

[0100] Angular indexing of the pressure-setting clip relative to the rod 2 and the finger 3 of the stem-cap can be provided. For this purpose, the groove 74 can be provided with one or two flats which provide an indexing and anti-rotation function for the clip relative to the rod.

[0101] Furthermore, similarly, as illustrated in [Fig.9], a flat 47 (or two) can be provided on the wall orifices, in order to impose a particular orientation of the plug at the time of insertion along the axis A.

Claims

Demands

1. An electrical / electronic housing (66) comprising at least one first busbar (4) with a first hole (41), a second busbar (5) with a second hole (52), the first and second holes being substantially coaxial, a housing with at least one orifice (60) located opposite the first and second holes, and a stem plug (10) for providing a connection between the first busbar (4) and the second busbar (5) and for sealing the orifice (60) provided in a wall (6) of said housing, the stem plug comprising: a disc-shaped body (1) having a first axis (A), a stem (2) extending, parallel to the first axis, from a first end (21) adjacent to the body to a second end (22), the stem being extended by a finger (3) extending, as a continuation of the stem, from the second end of the stem (22) to a free end (32),the finger being essentially formed as a cylinder of round or polygonal cross-section, with a diameter less than at least one transverse dimension of the second end of the rod, thus forming a shoulder (7) at the second end of the rod, said shoulder being able to push, directly or indirectly, the first busbar (4) against the second busbar, the finger (3) being inserted into the first hole and into the second hole, the shoulder (7) directly or indirectly pressing the first busbar (4) against the second busbar (5), and the body (1) hermetically sealing the orifice (60).

2. Electrical / electronic housing according to claim 1, wherein the free end of the finger (32) has a rounded, chamfered or conical end.

3. Electrical / electronic housing according to any one of claims 1 to 2, wherein the body comprises a peripheral rim with clipping lugs (9) and a support collar (8).

4. An electrical / electronic housing according to any one of claims 1 to 3, wherein a rod end is provided elastic pressure device configured to clamp together at least the first and second busbars (4,5).

5. Electrical / electronic housing according to any one of claims 1 to 3, wherein a spring (34) and a thrust washer (35) are provided, the spring being interposed between the shoulder (7) and the thrust washer, the thrust washer being configured to press on the first busbar (4).

6. Electrical / electronic housing according to any one of claims 1 to 5, wherein the body comprises an annular groove (17) open radially outwards in which an O-ring (16) is disposed.

7. Electrical / electronic housing according to any one of claims 1 to 3, wherein the body is provided on its outer peripheral edge with a screw thread (18) configured to cooperate with a complementary screw thread provided in the orifice.

8. Electrical / electronic housing according to any one of claims 1 to 3, in which the finger is equipped with a fir tree pin (33).

9. Electrical / electronic housing (66) according to claim 4, in which the pressurizing device comprises two tabs (15) which embrace the two busbars, and which each have an inclined distal portion (13) capable of causing the device to move apart simultaneously with the insertion of the stem plug, before the tabs return to a closed position upon contact with the first and second busbars, after passing beyond the second busbar.

10. Electrical / electronic housing according to any one of claims 1 to 9, wherein the orifice (60) has an orifice diameter (D6) at most equal to 3 times the diameter (D3) of the finger.

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