Patent Publication Number: US-7717723-B2

Title: Electrical plug-in connector and interlocking clip for interlocking of two housing parts

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to an electrical plug-in connector with a first housing part, a second housing part and at least one metal interlocking clip which is pivotally mounted on one of the two housing parts, two bearing journals being provided on the first housing part and two interlocking projections being made on the second housing part, the interlocking clip having two interlocking legs and a handle piece which connects the interlocking legs to one another and the interlocking legs each having a bearing arm with a recess for the bearing journal and an interlocking arm for overlapping an interlocking projection. In addition, the invention also relates to an interlocking clip for interlocking of two housing parts, especially two housing parts of an electrical plug-in connector, with two interlocking legs and a handle piece which connects the interlocking legs to one another. 
     2. Description of Related Art 
     Electrical plug-in connectors of the above mentioned type have been used for many years, especially in industry, and therefore, are often also called industrial plug-in connectors. The plug-in connectors generally have a housing base and a built-on housing as the first housing part and a housing cover or sleeve housing as the second housing part. Within the two housing parts there are generally several terminals which are electrically connected to one another to form a terminal strip, the terminal strips having plug-in contacts or jacks so that when the top part of the housing is slipped onto the bottom part of the housing, the terminals of the top part of the housing are electrically conductively connected to the corresponding terminals of the bottom part of the housing. 
     Since these industrial plug-in connectors are often used under extremely harsh conditions, the plug-in connectors must meet high tightness requirements, for which the two housing parts must be reliably interlocked with one another even when exposed to strong vibrations and high mechanical load. For this purpose, there must be at least one interlocking clip (often two interlocking clips) pivotally mounted on one of the two housing parts, and in the interlocked position, overlaps two interlocking projections or interlocking pins which are located on the other housing part, by which the two housing parts are held together with one another. 
     For example, European Patent Application EP 1 691 454 A2 discloses the initially described electrical plug-in connector. In this plug-in connector, the interlocking clip is punched out of a metal sheet in one piece and is bent such that it is made roughly U-shaped. The U-back or base leg of the interlocking clip here forms a handle piece, while the two U-legs are made as interlocking legs or interlocking clamps. The interlocking legs each have a bearing arm with a bearing recess for the articulated pins located on the first housing part and an interlocking arm for overlapping the interlocking pins which are located on the second housing part. 
     A similar plug-in connector is also disclosed by German Patent Application DE 10 2004 061 046 B4. In this plug-in connector, the interlocking clip is punched out of a metal sheet in one piece and bent. In this interlocking clip, the interlocking arm which overlaps the catch projection in the closed position is made rigid while the bearing arm is made as a spring leg. Because the known interlocking clips are punched out of a metal sheet and bent, production of the interlocking clip is relatively simple, and thus, is also associated only with low costs. However, here, the disadvantage is that punch edges are formed by punching out the interlocking clip and the interlocking projections on the second housing part can be damaged during interlocking as a result. 
     If the interlocking projections are made of plastic or of a relatively soft material, for example aluminum, when the interlocking clip is pivoted into the closed position, surface wear occurs on the interlocking projection; this can ultimately lead to the interlocking projections being parted. Even if the interlocking projections are made of a harder metal, when the interlocking clip is pivoted into the closed position friction occurs between the two metal parts, specifically between the interlocking projection and the interlocking arm, by which the surface of the two metals parts is involved so that corrosion can form more quickly. 
     SUMMARY OF THE INVENTION 
     Therefore, a primary object of this invention is to provide an electrical plug-in connector and an interlocking clip of the initially described type for two housing parts, especially for two housing parts of an electrical plug-in connector, in which the aforementioned disadvantages are avoided. At the same time it is to be ensured that reliable and permanent interlocking of the two housing parts is guaranteed by means of the interlocking clip. 
     The above object is achieved in an electrical plug-in connector of the initially described type in that there are two plastic parts and they are arranged on the two interlocking clips such that a section of a respective plastic part covers at least the free end surface of an interlocking arm which rubs over the interlocking projection when the interlocking clip is pivoted into the closed position. The arrangement of the plastic parts in accordance with the invention thus prevents the metallic interlocking clips from rubbing over the interlocking projections when the interlocking clip is pivoted into the closed position, since there is a section of a plastic part between the free end surface of one interlocking arm assigned to the respective interlocking projection and the assigned interlocking projection which thus slides over the interlocking projection when the interlocking clip is pivoted into the closed position. 
     According to one advantageous configuration, a depression made on the interlocking arm in the completely closed position of the interlocking clip overlaps the interlocking projection so that, on the one hand, the interlocking clip is locked in the closed position, and on the other hand, the force for interlocking the two housing parts is accommodated by the metal interlocking clip, especially the interlocking legs. Here, the section of the plastic part is dimensioned such that it does not cover the depression in the interlocking arm. When the interlocking clip is pivoted into the closed position the section of the plastic part thus forms a slide bearing with the interlocking projection which is made on the second housing part, while in the completely closed position of the interlocking clip the interlocking arm with its depression overlaps the interlocking projection. 
     Fundamentally, there are various possibilities for how the plastic part can be attached to the interlocking arm. For example, the plastic part could be cemented to the end of the interlocking arm or the interlocking arm in the corresponding region of the plastic part could be coated. According to one preferred embodiment of the invention, the two plastic parts assigned to the two interlocking legs are, however, each made as separate plastic injection molded parts. The two plastic parts are attached to the two interlocking legs, according to one embodiment of the invention, by there being on two interlocking legs spaced laterally relative to the interlocking arm, another arm being connected by way of a connecting bridge to the free end of the interlocking arm such that the plastic part with an attachment region is located between the interlocking arm and the other arm. The plastic part can be clamped with its attachment region between the interlocking arm and the other arm which is spaced laterally to it. 
     According to a preferred configuration of the invention, the two plastic parts which are each assigned to an interlocking leg are made such that they have two legs each and a back which connects the legs being formed on the first leg the section which covers the free end surface of the interlocking arm and a second leg corresponding to the recess in the bearing arm having a recess for a bearing journal. This execution of the plastic part, first of all, has the advantage that the plastic part, in the mounted state, is held additionally in its position by the bearing journal which is made on the first housing part extending not only through the recess in the bearing arm of the interlocking leg, but also through the corresponding recess in the second leg of the plastic part. When the interlocking clip is pivoted out of the opened position into the closed position the plastic part is thus also pivoted around the bearing journal. 
     A plastic part made in this way can, moreover, be additionally used to prevent unintentional, independent pivoting of the interlocking clip. For this purpose, between the recess in the second leg of the plastic part and the bearing journal on the first housing part, a force fit is formed which provides for the interlocking clip to be able to be pivoted only by applying a certain force. The force fit between the recess in the second leg of the plastic part and the bearing journal can be chosen such that, on the one hand, the interlocking clip can be pivoted by hand without a major expenditure of force, but on the other hand, remains in its respective position without intentional activation. 
     In the same manner as the plastic part according to the first embodiment has not only a section which covers the free end surface of the interlocking arm and an attachment region, but is made essentially U-shaped, preferably also there is not only another arm spaced laterally relative to the interlocking arm, but also an essentially U-shaped clip element. According to this preferred configuration, the interlocking clip has two U-shaped clip elements which are each spaced laterally to the two interlocking legs, and whose first leg is joined to the free end of the interlocking arm by way of a connecting bridge and is bent such that it is located spaced laterally relative to the interlocking arm. The second leg of the clip element is located spaced laterally relative to the bearing arm and has a recess which corresponds to the recess in the bearing arm for the bearing journal. The two legs of the clip element are connected to one another by way of a rigid connecting section which forms the U-back of the U-shaped clip element. 
     A clip element which is made in this way and which is connected in one piece to the interlocking arm and is bent by roughly 180° so that the first leg is aligned essentially parallel to the free end of the interlocking arm and the second leg is aligned essentially parallel to the bearing arm can be used not only to hold the plastic part, but at the same time, also can be used to provide overstretch protection for the interlocking leg. For this purpose, the recess in the second leg of the clip element is made as a slot. When the interlocking leg widens as it is slid onto the interlocking projection due to its slightly elastic property, the first leg of the clip element is also moved or entrained due to its connection to the interlocking arm, this motion being limited by the dimensions of the slot which is made in the second leg and through which the bearing journal extends. 
     If the two housing parts, which are held together by way of the interlocking clip, are pulled apart by external forces, the expansion of the interlocking legs is limited by the maximally possible path of motion of the bearing journal in the slot of the second leg of the clip element. Expansion of the interlocking legs beyond this is prevented by the rigid clip element so that the interlocking leg is prevented from being overstretched when great forces are acting on the two housing parts. The forces which act on the interlock between the two housing parts are then accommodated by the rigid clip element. Since, as a result of the formation of the slot in the second leg of the clip element, the rigid clip element enables a certain, allowable expansion of the interlocking legs, at the same time, the pivoting of the interlocking clip into the closed position is facilitated since the interlocking arm can be pivoted more easily onto the interlocking projection due to the limited elastic property of the interlocking leg. 
     The aforementioned object in an interlocking clip for interlocking of two housing parts, with two interlocking legs and a handle piece which connects the interlocking legs to one another, is achieved in that there are two plastic parts and they are arranged on the interlocking legs such that a respective section of the plastic part covers at least the free end surface of the interlocking arm which faces the respective bearing arm and which rubs over a second interlocking projection on the second housing part when the interlocking clip is pivoted into the closed position. With respect to the advantages of an interlocking clip which is made in this way and which can be used especially for interlocking of the two housing parts of an electrical plug-in connector, reference is made to the above in conjunction with the electrical plug-in connector in accordance with the invention. 
     According to one advantageous configuration of the interlocking clip in accordance with the invention, the two interlocking arms of the two interlocking legs each have a depression for holding one interlocking projection made on the housing part at a time in the closed position of the interlocking clip, the section of the plastic part which covers the free end surface of the interlocking arm being dimensioned such that it does not cover the depression. As described beforehand in conjunction with the electrical plug-in connector, this results in that the depression of a metallic interlocking arm overlaps the two interlocking projections in the closed position of the interlocking clip. 
     According to another advantageous configuration of the interlocking clip in accordance with the invention, which will be only briefly mentioned here, an actuating opening is formed in the handle piece into which a tool, especially the tip of a screwdriver, can be inserted. In this way, the actuation of the interlocking clip can be facilitated when the interlocking clip or the handle piece is only poorly accessible due to restricted space conditions or due to the attachment position of the electrical plug-in connector. Moreover, a greater force for opening or closing the interlocking clip can be applied by a screwdriver which has been inserted into the actuating opening. 
     If the two interlocking legs and the handle piece are integrally connected to one another, the interlocking clip can be produced especially easily as punched and bent part. The one-piece execution of the interlocking clip also increases its mechanical stability so that with simultaneously simple production a durable interlocking clip which thus ensures reliable interlocking can be made available. 
     In particular, there are a host of possibilities for embodying and developing the electrical plug-in connector and the interlocking clip in accordance with the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an electrical plug-in connector, with a first housing part and a second housing part in a disconnected state, 
         FIG. 2  shows the electrical plug-in connector of  FIG. 1  in the locked state, 
         FIG. 3  is a perspective of an interlocking clip in accordance with the invention, 
         FIG. 4  shows the interlocking clip of  FIG. 3  without the plastic parts, 
         FIG. 5  is a separate perspective representation of the two plastic parts of the interlocking shown in  FIG. 3 , and 
         FIG. 6  shows a part which has been punched out of spring steel and from which an interlocking clip as shown in  FIG. 3  can be produced. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 &amp; 2  show an electrical plug-in connector  1  which has a housing base as the first housing part  2  and a housing cover as the second housing part  3 . Within the two housing parts  2 ,  3 , there can be several terminals which are connected to one another to form a terminal strip or contact insert for connection of the individual leads of an electrical cable which are, however, not shown in the figures since this invention relates to interlocking of the two housing parts  2 ,  3 . 
     For attachment or interlocking of the two housing parts  2 ,  3 , to one another, in the illustrated embodiment, there are two identical interlocking clips  4  which are pivotally attached to the first housing part  2 . To support the interlocking clips  4 , there are two bearing journals  5  for each clip  4  so that, in the illustrated embodiment, the first housing part  2  has a total of four bearing journals  5  which are arranged in pairs opposite one another on the two lengthwise sides  6  of the first housing part  2 . 
     To interlock the second housing part  3 , i.e., the top part of the housing, to the first housing part  2 , on the second housing part  3  four interlocking projections  7  made as interlocking pins are formed. The interlocking pins  7  are arranged in pairs opposite one another on the two lengthwise sides  8  of the second housing part  3 , and the interlocking pins  7  can be made either in one piece with the second housing part  3  or attached, especially can be riveted, as separate interlocking pins  7  to the second housing part  3 . Preferably, both of the housing parts  2 ,  3  and also the bearing journals  5  and the interlocking projections  7  are made of metal. 
     Instead of the attachments of the two interlocking clips  4  to the housing base  2  as shown in  FIGS. 1 &amp; 2 , the interlocking clips  4  can also be pivotally mounted on the housing cover  3 , then the bearing journals  5  would be located on the housing cover  3 , and accordingly, the interlocking projections  7  would be located on the housing base  2 . Moreover, the interlocking clips  4 , which are made as transverse clips in the figures, can also be made as lengthwise clips so that then the bearing journals  5  and the interlocking projections  7  are located not on the lengthwise sides  6 ,  8  of the housing base  2  or the housing cover  3 , but on their transverse sides  9 ,  10 . Finally, for interlocking of the two housing parts  2 ,  3 , for certain electrical plug-in connectors  1 , the use of only one interlocking clip  4  can also be sufficient. If the electrical plug-in connector  1  has only one interlocking clip  4 , the bearing journals  5  are generally located in the middle of the lengthwise sides  6  or the transverse sides  9  of the housing base  2  or in the middle of the lengthwise sides  8  or the transverse sides  10  of the housing cover  3 . 
     The interlocking clip  4 , shown separately in  FIG. 3 , has two opposite interlocking legs  11 ,  12  and a handle piece  13  which connects the interlocking legs  11 ,  12  to one another, the two interlocking legs  11 ,  12  each having a bearing arm  14  with a recess  15  for a bearing journal  5  and an interlocking arm  16  for overlapping the interlocking projection  7  in the closed position of the interlocking clip  4 . The two roughly V-shaped interlocking legs  11 ,  12  are each made flexible such that the interlocking legs  11 ,  12  can slightly spread apart when the interlocking clip  4  is pivoted out of the opened position shown in  FIG. 1  into the closed position shown in  FIG. 2 . In the closed position of the interlocking clip  4 , the two interlocking arms  16  overlap the corresponding interlocking projections  7  on the top part  3  of the housing, by which the two housing parts  2 ,  3  are tightly joined to one another. To ensure sufficient tightness of the plug-in connector  1 , there is a rubber seal  17  in the groove in the first housing part  2  which seals the two housing parts  2 ,  3  relative to one another in the state interlocked to one another. 
     As is especially apparent from  FIG. 3  as well as  FIGS. 4 &amp; 5 , on the two interlocking legs  11 ,  12  of the interlocking clip  4 , there are two plastic parts  18  which each have a section  19  which slides over the interlocking projections  7  when the interlocking clip  4  pivots into the closed position. The section  19  is made or arranged such that it covers the free end surface  20  of the interlocking arm  16  which would rub over an interlocking projection  7  when the interlocking clip  4  is pivoted into the closed position. This prevents the surface of the interlocking projection  7  from wearing off when the interlocking clip  4  is pivoted into the closed position; this ultimately could lead to the interlocking projection  7  being damaged or even parted. This danger prevails especially even when the interlocking projections  7  is made of a softer metal than the interlocking clip  4 , for example, of aluminum or of plastic, and when the interlocking clip  4  is made as a punched and bent part and thus has rough or sharp punched edges. 
     The arrangement of the plastic parts  18  in the interlocking legs  11 ,  12  prevents damage to the interlocking projections  7  since, when the interlocking clip  4  is pivoted into the closed position, the respective section  19  of the two plastic parts  18  slides over the interlocking projections  7 . In the representation of the plug-in connector  1  in  FIG. 2 , the left-hand interlocking clip  4  is in the not yet entirely closed position in which the section  19  of the plastic part  18  slides over the interlocking projection  7 . In contrast, the right-hand interlocking clip  4  is in the completely closed position in which the depression  21  which is formed on the interlocking arm  16  overlaps the interlocking projection  7 . This leads, on the one hand, to the interlocking clip  4  locking in the completely closed position, and on the other hand, the force for interlocking of the two housing parts  2 ,  3  being applied by the metal interlocking clip  4 , especially the two interlocking legs  11 ,  12 . The section  19  of the plastic part  18  is dimensioned such that it does not cover the depression  21 . 
     It is apparent from  FIG. 5  that the two plastic parts  18  are each made roughly U-shaped, specifically, having two legs  22 ,  23  and a back  24  which connects the legs  22 ,  23 . On the first leg  22 , a section  19  is made which covers the free end surface  20  of the interlocking arm  16 . In the second leg  23 , corresponding to the recess  15  in the bearing arm  14 , there is a recess  25  for a bearing journal  5  so that, when the interlocking clip  4  is pivoted out of the opened into the closed position, the two plastic parts  18  are also pivoted around the bearing journals  5 . The recess  25  is made as a slot so that the plastic part  18  has a certain dynamic play relative to the bearing journal in the vertical direction. The transverse extension of the recess  25  is somewhat smaller than the diameter of the bearing journal so that a force fit is formed between the recess  25  and the bearing journal  5 . The force fit between the recess  25  in the plastic part  18  and the bearing journal  5  is chosen such that the interlocking clip  4 , on the one hand, can be pivoted by hand, without a great expenditure of force, and on the other hand, however, it remains in its respective position without intentional actuation. Unintentional pivoting or “folding up” of the interlocking clip  4  can thus be prevented. 
     Fixing of the plastic parts  18  relative to the interlocking legs  11 ,  12  takes place, besides via the bearing journal  5 , especially by two clip elements  26  being formed on the interlocking clip  4  and each of which is spaced laterally relative to a respective one of the interlocking legs  11 ,  12 . The first leg  27  of the U-shaped clip element  26  is connected to the free end of the interlocking arm  16  by way of a connecting bridge  28 , the clip element  26  being bent by roughly 180° such that the first leg  27  is located parallel to the interlocking arm  16  and the second leg  29  of the clip element  26  is located parallel to the bearing arm  14 . The clip element  26  is arranged spaced apart from the interlocking leg  11 ,  12  such that the plastic parts  18  are held in the intermediate space between the clip elements  26  and the respective interlocking leg  11 ,  12 . 
     The execution of the clip elements  26  on the interlocking clip  4  is thus used, first of all, to accommodate and hold the two plastic parts  18 . Moreover, the clip elements  26  also act as overstretch protection for the two interlocking legs  11 ,  12 . For this purpose, there is a recess, in the form of a slot  30 , in the second leg  29  of the clip element  26 , the slot  30  receiving a bearing journal  5 . Moreover, the connecting section  31  which connects the two legs  27 ,  29  of the clip element  26  to one another is made so rigidly that the clip element  26  is prevented from expanding. 
     If the interlocking clip  4  is pivoted out of the opened position into the closed position, when the interlocking arm  16  slides onto the interlocking projection  7 , the interlocking leg  11 ,  12  widens slightly. The interlocking arm  16  is deflected somewhat up in the arrangement of the interlocking clip  4  which is shown in  FIG. 2 . Since the first leg  27  of the clip element  26  is connected to the interlocking arm  16  by way of the connecting bridge  28 , the first leg  27  is also moved up, the clip element  26  also moving altogether up as a result of the slot  30  which is formed in the second leg  29 . Since the clip element  26  is rigid, the motion of the first leg  27  up is limited by the dimensions of the slot  30 . If the lower edge of the slot  30  strikes the lower edge of the bearing journal  5 , further motion of the clip element  26  up is blocked. At the same time further widening of the interlocking leg  11  is also prevented. 
     If the two housing parts  2 ,  3  which have been locked to one another by way of the interlocking clip or clips  4  are pulled apart from one another by external forces, widening of the interlocking legs  11 ,  12  is limited by the maximum possible path of motion of the bearing journal  5  in the slots  30  of the clip elements  26 . Expansion of the interlocking legs  11 ,  12  which goes beyond this is prevented by the rigid clip elements  26  so that the clip elements  26  act as overstretch protection for the interlocking legs  11 ,  12 . 
     The plastic part  18 , which with the exception of the section  19 , has essentially the same external dimensions as the clip element  26 , with the first leg  22  as the first attachment region is located between the interlocking arm  16  and the first leg  27 , and with the second leg  23  as the second attachment region located between the bearing arm  14  and the second leg  29 . The section  19  of the plastic part  18  is dimensioned such that it covers both the end surface  20  of the interlocking arm  16  as well as the corresponding surface  32  of the first leg  27  of the clip element  26 . The section  19  thus has a width which corresponds roughly to the sum of the width of the interlocking arm  16 , the width of the first leg  27  and the distance between the interlocking arm  16  and the first leg  27 . 
     Moreover, a bead-like projection  33  is formed on the section  19  of the plastic part  18  which engages a corresponding recess  34  in the interlocking arm  16  and a recess  35  in the first leg  27  of the clip element  26  so that the two plastic parts  18  are connected positively to the interlocking legs  11  and  12  and the clip elements  26  at least in the region of the sections  19 . 
     To be able to easily actuate the interlocking clips  4  even when they are accessible by hand only with difficulty as a result of the limited space conditions or as a result of a special installation position of the electrical plug-in connector  1 , in the handle piece  13  an actuating opening  36  is made for an actuating tool, especially the shaft of a screwdriver. By inserting the tip of a screwdriver through the actuating opening  36 , a larger force can be applied for opening or closing the interlocking clip  4  due to the lever arm having been lengthened in this way. 
       FIG. 6  shows that the interlocking clip  4  in accordance with the invention can be made as a punched and bent part, specifically can be simply punched out of a metal part, especially out of spring steel, and then bent into its shape shown in  FIG. 4 . Moreover, it is apparent from  FIG. 6  that the interlocking clip  4  is made entirely in one piece, especially also the clip elements  26  are connected in one piece with one interlocking arm  16  of a respective interlocking leg  11 ,  12  by way of the connecting bridge  28 .