Abstract:
Systems and techniques are described to provide a bulb insertion structure of a vehicular lamp which allows bulb replacement and accurate positioning of a bulb with respect to a reflector. In general, in one implementation, a bulb insertion structure of a vehicular lamp includes a plurality of fixing protrusions formed on an outer periphery of a rear end portion of a cylindrical socket fixture fixed in a bulb insertion hole of a reflector; a plurality of engaging protrusions formed on an outer periphery of a focus ring provided on a bulb and corresponding to the fixing protrusions; and a cup-shaped socket covering the outer periphery of the socket fixture from the rear, the socket incorporating a spring for pressing forward the rear end portion of the accommodated bulb, and having an outer peripheral wall provided with, at multiple locations corresponding to the fixing protrusions, an engaging notch (J-slot) for holding the engaging protrusion and the fixing protrusion overlapped together. In this structure, the J-slot is provided with an engaging recess portion for holding the engaging protrusion in the J-slot when the socket is pulled out from the socket fixture. Furthermore, a slit, which extends continuously from the engaging recess portion of the J-slot in a circumferential direction, is formed of a size that allows the engaging protrusion and the fixing protrusion to only pass therethrough separately.

Description:
BACKGROUND 
   The following description relates to techniques and methods for inserting a bulb into a vehicular lamp. 
   A conventional bulb insertion structure of a vehicular lamp (Japanese Patent Laid-Open Publication No. 9-219103), as shown in  FIGS. 8 and 9 , is constituted by a cylindrical socket fixture  2  fixed to a bulb insertion hole  1   a  of a reflector  1 , and a cup-shaped socket  6  which can accommodate therein a rear end portion of a bulb  4  and covers an outer periphery of the socket fixture  2  from the rear. The socket fixture  2  and the bulb  4  are provided with three fixing protrusions  2   a  and three engaging protrusions  5   a  that respectively correspond, and the outer periphery of the socket  6  is provided with three J-shaped slots (hereafter referred to as “J-slot”)  7  at positions corresponding to the protrusions  2   a  and  5   a . Furthermore, a spring  8  for energizing the bulb  4  forward is provided in an inner portion of the socket  6  in which the rear end portion of the bulb  4  can be accommodated. 
   To insert the bulb  4  into the bulb insertion hole  1   a , as indicated by an arrow A in  FIG. 9 , the bulb  4  is inserted in the socket fixture  2  to conform the engaging protrusion  5   a  with the fixing protrusion  2   a . Next, as indicated by an arrow B in  FIG. 9 , the socket  6  covers the socket fixture  2  such that the J-slot  7  aligns with both protrusions  5   a  and  2   a . Then, when the socket  6  is pushed forward against the energizing force of the spring  8  and rotated clockwise, the fixing protrusion  2   a  and the engaging protrusion  5   a  engage with the J-slot  7 . As a result, the socket  6  is fixed to the socket fixture  2 , creating a state where the bulb  4  is inserted into the bulb insertion hole  1   a  as shown in  FIG. 8 . 
   Furthermore, the J-slot  7  is provided with an engaging recess portion  7   a  for holding the engaging protrusion  2   a  when the socket  6  is pulled out, so that the socket  6  can be detachably attached with the bulb  4  in an integrated state. 
   That is by covering the socket fixture  2  with the socket  6  integrated with the bulb  4  by engaging the engaging protrusion  5   a  with the J-slot  7  such that the J-slot  7  conforms with the fixing protrusion  2   a , in addition to pushing the socket  6  against the energizing force of the spring  8  and rotating the socket  6  clockwise, the fixing protrusion  2   a  and the engaging protrusion  5   a  engage with the J-slot  7 . Consequently, the bulb  4  is inserted into the bulb  4  insertion hole as shown in  FIG. 8 . 
   Furthermore, to pull the bulb  4  out from the bulb insertion hole  1   a , the engaging protrusion  5   a  engages with the engaging recess portion  7   a , and (a protrusion-sliding slit  7   b  of) the J-slot  7  opens when the socket  6  is pushed in against the energizing force of the spring  8 . Therefore, by rotating the socket  6 , the fixing protrusion  2   a  slides along the slit  7   b , disengaging the fixing protrusion  2   a  and the J-slot  7 , and thus the socket  6  integrated with the bulb  4  can be pulled out from the socket fixture  2 . 
   However, in the conventional structure described above, cases occur in which the socket  6  is fitted in an incomplete form when fitting the socket  6  integrated with the bulb  4  to the socket fixture  2 . 
   As shown in  FIG. 10A , the bulb  4  and the socket  6  may be integrated in a manner such that the engaging protrusion  5   a  on the bulb side abuts the protrusion-sliding slit  7   b  of the J-slot  7 . When the socket  6  integrated with the bulb  4  is fitted to the socket fixture  2 , the socket  6  is pressed and rotated as shown in  FIG. 10A  and by arrows A 1  and A 2  in  FIG. 10B , and the engaging protrusion  5   a  and the socket  6  integrally rotate with respect to the fixing protrusion  2   a  as shown in  FIG. 10B . The engaging protrusion  5   a  may not slide with respect to the J-slot  7 , and only the fixing protrusion  2   a  slides as indicated by an imaginary line in  FIG. 10B . Then, as shown in  FIG. 10C , the fixing protrusion  2   a  engages with the J-slot  7 , however, the engagement between the engaging protrusion  5   a  on the bulb side and the J-slot  7  is maintained in an incomplete state. 
   SUMMARY 
   In one aspect, the bulb insertion structure includes a plurality of tongue-like fixing protrusions formed on an outer periphery of a rear end portion of a cylindrical socket fixture fixed in a bulb insertion hole of a reflector; a plurality of engaging protrusions formed on an outer periphery of a focus ring provided on a bulb and corresponding to the fixing protrusions; and a cup-shaped socket covering the outer periphery of the socket fixture from the rear, the socket incorporating a spring for pressing forward the rear end portion of the accommodated bulb and having an outer peripheral wall provided with, at multiple locations corresponding to the fixing protrusions, an engaging notch which holds the engaging protrusion and the fixing protrusion overlapped together. The engaging notch is provided with an engaging recess portion for holding the engaging protrusion in the engaging notch when the socket is pulled out from the socket fixture. A slit, which extends continuously from the engaging recess portion of the engaging notch in a circumferential direction, is formed of a size that allows the engaging protrusion and the fixing protrusion to only pass therethrough separately. 
   The systems and techniques described here may provide one or more of the following advantages. In some implementations, the bulb insertion structure of a vehicular lamp allows bulb replacement and accurate positioning of a bulb with respect to a lamp reflector. 
   Details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages may be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects will now be described in detail with reference to the following drawings. 
       FIG. 1  is a longitudinal cross-sectional view of a headlamp for a motorcycle. 
       FIG. 2  is an exploded perspective view around a bulb insertion hole of the headlamp of  FIG. 1 . 
       FIG. 3  is an enlarged view showing a detailed shape of a J-slot formed on a cup-shaped socket. 
       FIGS. 4A–4B  are views illustrating a relation between a depth of an engaging recess portion of a J-slot and a thickness of an engaging protrusion. 
       FIGS. 5A–5C  are perspective views illustrating movement of an engaging protrusion and a fixing protrusion in an engaging notch when a bulb is inserted or removed. 
       FIGS. 6A–6B  a view illustrating an operation of a protrusion-sliding slit in an engaging notch when a socket integrated with the bulb is fitted to a socket fixture in a state where engagement between the engaging protrusion and the engaging notch is incomplete. 
       FIG. 7  is an enlarged front elevational view of the engaging notch illustrating the operation of the protrusion-sliding slit. 
       FIG. 8  is a longitudinal cross-sectional view showing a conventional bulb insertion structure. 
       FIG. 9  is an explanatory view illustrating a condition in which a bulb is inserted into a bulb insertion hole according to the conventional bulb insertion structure. 
       FIGS. 10A–10C  illustrate a condition in which a fixing protrusion is engaged with a J-slot in a state where engagement between an engaging protrusion and the J-slot is incomplete, according to a conventional bulb insertion structure. Like reference symbols in the various drawings indicate like elements. 
   

   DETAILED DESCRIPTION 
   The present disclosure relates to a bulb insertion structure of a vehicular lamp in which a socket, an outer periphery of which is provided with an engaging notch for holding a fixing protrusion on a socket fixture side and an engaging protrusion on a bulb side in an overlapped state, is fitted to a socket fixture fixed into a bulb insertion hole of a reflector, and more particularly to a bulb insertion structure in which an engaging recess portion for holding the engaging protrusion is provided in the engaging notch, and a socket integrated with a bulb can be detachably attached to the socket fixture. 
   To insert the bulb into the bulb insertion hole, the engaging protrusion of a focus ring is first engaged with the engaging notch so as to integrate the bulb with the socket. Then, the socket covers the socket fixture from the rear such that the fixing protrusion aligns with the engaging notch, and the socket is pressed forward against the energizing force of the spring. In this case, if the engaging protrusion is appropriately engaged with the protrusion latching portion in the engaging notch as shown in  FIG. 5A , the engaging protrusion of the focus ring engages with the engaging recess portion in the engaging notch, and the fixing protrusion of the socket fixture comes to a position that aligns with the protrusion-sliding slit. In this case, if the socket is rotated in a direction of engagement of the fixing protrusion and the engaging notch, the engaging notch slides along the fixing protrusion, and the fixing protrusion overlaps the engaging protrusion and comes to a position that aligns with the protrusion latching portion in the engaging notch. In this case, if the pressing force applied to the socket is released, the overlapping fixing protrusion and engaging protrusion are held engaged with (the protrusion latching portion of) the engaging notch by the energizing force of the spring. That is, the bulb is inserted into the bulb insertion hole. 
   To remove the bulb from the bulb insertion hole, if the socket is pressed forward against the energizing force of the spring, in a state where the overlapping fixing protrusion and engaging protrusion are held in (the protrusion latching portion of) the engaging notch, the engaging protrusion of the focus ring engages with the engaging recess portion in the engaging notch, and the fixing protrusion of the socket fixture comes to a position that aligns with the slit extending in a circumferential direction. In this case, if the socket is rotated in a direction of disengagement of the fixing protrusion and the engaging notch, the engaging notch holding the engaging protrusion in the engaging recess portion slides along the fixing protrusion (the fixing protrusion of the socket fixture and the engaging protrusion of the focus ring slide relatively), and the fixing protrusion comes to a position that aligns with the opening portion of the engaging notch. In this case, if the pressing force applied to the socket is released, a reactive force of the energizing force of the spring pushes the socket out of the socket fixture. 
   When inserting the bulb into the bulb insertion hole, if the bulb is not appropriately integrated with the socket as shown in  FIG. 6A , for example, if the engaging protrusion is not correctly engaged with the protrusion latching portion in the engaging notch as in a case where the engaging protrusion is within the slit extending in the circumferential direction in the engaging notch, an incomplete attachment state is created in the conventional structure, in which only the fixing protrusion is engaged with the protrusion latching portion in the engaging notch. 
   The slit extending in the circumferential direction in the engaging notch is formed of a size that allows the engaging protrusion and the fixing protrusion only to pass therethrough separately. Accordingly, if the engaging protrusion is not correctly engaged with the protrusion latching portion in the engaging notch, such as when, for example, the engaging protrusion is within the slit in the engaging notch, the fixing protrusion can not come to a position that aligns with the slit (the fixing protrusion can not enter the slit in the engaging notch). Thus, the socket can not be rotated in the direction of engagement of the fixing protrusion and the engaging notch. Therefore, in this case, an operator who rotates the socket can recognize that the engagement between the engaging protrusion and engaging notch is incomplete. By again performing the operation to fit the socket after correctly engaging the engaging protrusion with (the protrusion latching portion in) the engaging notch and correctly integrating the bulb with the socket anew, the socket can be fixed to the socket fixture. Namely, unlike in the conventional structure, the socket does not become fixed to the socket fixture in a state where the engagement between the engaging protrusion and the engaging notch is incomplete. 
   In an implementation, a depth of the engaging recess portion is formed generally identical to a thickness of the engaging protrusion. 
   To insert or remove the bulb with respect to the bulb insertion hole (to attach or detach the socket with respect to the socket fixture), the socket is pressed forward with respect to the socket fixture against the energizing force of the spring, so as to engage the engaging protrusion of the focus ring with the engaging recess portion in the engaging notch. Hence, the fixing protrusion of the socket fixture and the slit extending in the circumferential direction in the engaging notch come to a mutually aligned positions in the circumferential direction, and the socket can be rotated in the circumferential direction of engagement or disengagement (the engaging notch can slide along the fixing protrusion). 
   Furthermore, if a depth of the engaging recess portion is greater than a thickness of the engaging protrusion, as shown in  FIG. 4A , the fixing protrusion during pressing of the socket is pushed to a position beyond a position of the slit that extends in the circumferential direction. Thus, the fixing protrusion does not align with the slit, and therefore, the socket can not be rotated smoothly. On the other hand, if the depth of the engaging recess portion is less than the thickness of the engaging protrusion, as shown in  FIG. 4B , a width of the slit needs to be increased to prevent blocking of the slit by the engaging protrusion (focus ring). Accordingly, a longitudinal length of the socket is increased, thereby increasing the amount of protrusion of the socket toward the rear of the reflector. 
   In an implementation, the depth of the engaging recess portion is generally the same as the thickness of the engaging protrusion. If the socket is pressed forward against the energizing force of the spring, the engaging protrusion engaged with the engaging recess portion becomes substantially flush with a periphery portion of the slit. Therefore, the fixing protrusion and the slit align in the circumferential direction, and thus the socket can be rotated smoothly (the engaging notch can slide along the fixing protrusion). 
   In an implementation, both a cap of the bulb provided with the focus ring and the socket are made of metal, and the socket is integrally covered with a detachable socket cover made of synthetic resin, an outer periphery of which is provided with a protrusion for a fingerhold. 
   Although the socket integrated with the bulb may become hot due to heat generated by the bulb, an operator can attach (insert) or detach the socket (bulb) without incurring a burn injury by holding the socket cover made of synthetic resin, which integrally covers the bulb, has low heat conductivity, and is easy to hold. 
     FIG. 1  is an illustrative vehicular lamp having a container-like lamp body  10 , a front side of which is open. A front opening portion of the lamp body  10  is assembled with a front lens  12 , defining a lamp chamber S. An aluminum reflector  14 , which is fixed to the lamp body  10  by fixing means (not shown), is accommodated in the lamp chamber S. A bulb  20  as a light source is inserted, via a metal socket fixture  30  and a metal socket  40 , into a bulb insertion hole  15  provided at a rear top portion of the reflector  14 . 
   The socket fixture  30  has a cylindrical shape, with three bent legs  32  formed on an outer periphery of a front end portion thereof. These legs  32  are fixed, by screws  33 , to bosses  16  erected on a peripheral portion of the bulb insertion hole  15  so as to be integrated with the reflector  14 . An outer periphery of a rear end portion of the socket fixture  30  is formed with three tongue-like fixing protrusions  34  at predetermined intervals in a circumferential direction. 
   Referring to  FIG. 2 , the bulb  20  is constructed such that a metal cap  22  is integrated with a base end portion of a glass bulb  21  incorporating a filament. A connecting terminal  23  is exposed at a rear end portion of the bulb  20 . Furthermore, an outer periphery of the cap  22  is provided with a metal focus ring  24 , and three tongue-like engaging protrusions  26  that correspond to the fixing protrusions  34  on the socket fixture  30  side are formed on an outer periphery of the focus ring  24 . 
   The socket  40  into which the rear end portion of the bulb  20  can be accommodated is formed in a cup shape with notches, the front side of which is open, and a compression coil spring  42  is incorporated in an inner side of the rear end portion of the socket  40 , such that an energizing force of the spring  42  acts on the rear end portion of the bulb  20  via a base plate  43  (see  FIG. 1 ) slidably attached in an axial direction. A power cord  44  that may be connected to a contact terminal  23  of the base plate  43  and lead out the rear end opening portion of the socket  40 . 
   An outer peripheral wall of the socket  40  is formed with three J-shaped slots (hereafter referred to as “J-slot”) as engaging notches that correspond to the engaging protrusions  26  on the bulb  20  side and the fixing protrusions  34  on the socket fixture  30  side. The socket  40  covers an outer periphery of the socket fixture  30  from the rear such that the engaging protrusions  34  and the fixing protrusions  26  can be held together overlapped. 
     FIG. 3  illustrates the J-slot  46  that includes a guiding slit  46   a  extending in an axial direction on the J-slot opening side, a protrusion-sliding slit  46   b  that extends in a circumferential direction and corresponds to a J-shaped crossbar portion, a protrusion latching portion  46   c  for retaining the engaging protrusion  26  and the fixing protrusion  34 , and an engaging recess portion  46   d  for engaging the engaging protrusion  26 , formed at a position opposing the protrusion latching portion  46   c . Respective widths of the guiding slit  46   a , the latching portion  46   c , and the engaging recess portion  46   c  are formed of a size that conforms to a width W of the engaging protrusion  26  and the fixing protrusion  34 . 
   Referring to  FIG. 4A , a depth h of the latching portion  46   c  may be formed of a size so that the engaging protrusion  26  and the fixing protrusion  34  can be engaged and held together overlapped. The engaging recess portion  46   d  may be of a size that can accommodate the engaging protrusion  26 , and in particular, a depth H thereof (refer to  FIG. 3 ) conforms to a thickness T 1  of the engaging protrusion  26 . Thus, as the engaging protrusion  26  engages with the engaging recess portion  46   d , a periphery  46   b   1  of the protrusion-sliding slit  46   b  on the engaging recess portion  46   d  side becomes substantially flush with a front face  26   a  of the engaging protrusion  26 . Accordingly, the fixing protrusion  34  can slide smoothly into the protrusion-sliding slit  46   b , enabling smooth rotation of the socket  40  in the circumferential direction. 
   That is, if a depth H 1  of the engaging recess portion  46   d  is greater than the thickness T 1  of the engaging protrusion  26 , as shown in  FIG. 4A , the fixing protrusion  34  during pressing of the socket  40  is pushed to a position beyond a position of the protrusion-sliding slit  46   b . Thus, the fixing protrusion  34  does not align with the protrusion-sliding slit  46   c , and therefore, the socket  40  can not be rotated smoothly. On the other hand, if a depth H 2  of the engaging recess portion  46   d  is less than the thickness T 1  of the engaging protrusion  26 , as shown in  FIG. 4B , a width d 2  of the protrusion-sliding slit  46   b  needs to be increased to prevent blocking of the slit by the engaging protrusion  26  (focus ring  24 ). Accordingly, as indicated by an imaginary line in  FIG. 4B , a longitudinal length of the socket  40  is increased, thereby increasing the amount of protrusion of the socket  40  toward the rear of the reflector  14 . Therefore, the structure according to the present embodiment is such that the engaging recess portion  46   d  conforms to the thickness T 1  of the engaging protrusion  26 , so that the aforementioned problems do not occur. 
   Furthermore, a width d of the protrusion-sliding slit  46   b  (refer to  FIG. 3 ) is formed of a size that allows the engaging protrusion  34  and the fixing protrusion  26  to only pass therethrough separately. In an implementation, the thickness of the engaging protrusion  34  is 0.8 mm, the thickness of the fixing protrusion  26  is 0.6 mm, and the width of the protrusion-sliding slit  46   b  is 1.2 mm. The dimensions are selected to prevent the socket  40  being fitted to the socket fixture  30  with the engaging protrusion  34  in an incomplete state of engagement with the J-slot. As a result, the bulb  20  can be correctly inserted into the bulb insertion hole  15  via the socket  40  and the socket fixture  30 . 
   To insert the bulb  20  into the bulb insertion hole  15 , the engaging protrusion  26  of the focus ring  24  is first engaged with the J-slot  46  so as to integrate the bulb  20  with the socket  40 . Then, the socket  40  covers the socket fixture  30  from the rear such that the fixing protrusion  26  aligns with the J-slot  46 , and the socket  40  is pressed forward against the energizing force of the spring  42 . In this case, if the engaging protrusion  26  is appropriately engaged with the protrusion latching portion  46   c  in the J-slot  46  as shown in  FIG. 5A , the focus ring  24  is pushed toward the front end portion of the socket fixture  30 . The engaging protrusion  26  engages with the engaging recess portion  46   d  in the J-slot  46 , and the fixing protrusion  34  of the socket fixture  30  comes to a position that aligns with the protrusion-sliding slit  46   b  as shown in  FIG. 5B . If the socket  40  is rotated in a direction of engagement of the fixing protrusion  34  and the J-slot  46  (a direction indicated by an arrow B in  FIG. 5B ), the protrusion-sliding slit  46   b  of J-slot  46  slides along the fixing protrusion  34  so that the fixing protrusion  34  overlaps the engaging protrusion  26  and comes to a position (refer to an imaginary line shown in  FIG. 5B ) that aligns with the protrusion latching portion  46   c  in the J-slot. In this case, if the pressing force applied to the socket  40  is released, the overlapping fixing protrusion  34  and engaging protrusion  26  are held engaged with the protrusion latching portion  46   c  by the energizing force of the spring  42  (refer to  FIG. 5C ). That is, the bulb  20  is inserted into the bulb insertion hole  15 . 
   To remove the bulb  20  from the bulb insertion hole  15 , if the socket  40  is pressed forward against the energizing force of the spring  42  in a state where the overlapping fixing protrusion  34  and engaging protrusion  26  are held in the protrusion latching portion  46   c  of the J-slot  46  as shown in  FIG. 5C , the engaging protrusion  26 , and the fixing protrusion  34  come to a position engaged with the engaging recess portion  46   d  that aligns with the protrusion-sliding slit  46   b  (refer to the imaginary lines in  FIG. 5B ). If the socket  40  is rotated in a direction of disengagement of the fixing protrusion  34  and the J-slot  46  (a direction indicated by an arrow B′ in  FIG. 5B ), the J-slot  46  holding the engaging protrusion  26  in the engaging recess portion  46   d  slides along the fixing protrusion  34  (the fixing protrusion  34  and the engaging protrusion  26  slide relatively), and the fixing protrusion  34  comes to a position that aligns with the guiding slit  46   a  of the J-slot  46 . If the pressing force applied to the socket  40  is released, a reactive force of the energizing force of the spring  42  pushes the socket  40  out of the socket fixture  30 . 
     FIGS. 6A–6B  illustrate an arrangement where the bulb  20  is not completely integrated with the socket  40  when inserting the bulb  20  into the bulb insertion hole  15 . For example, in  FIG. 6A  the engaging protrusion  26  is not correctly engaged with the protrusion latching portion  46   c  in the J-slot  46 . The engaging protrusion  26  is within the protrusion-sliding slit  46   c  in the J-slot  46 . Because the protrusion-sliding slit  46   b  in the J-slot  46  is formed of a size that allows the engaging protrusion  26  and the fixing protrusion  34  to only pass therethrough separately, the fixing protrusion  34  can not come to a position that aligns with the protrusion-sliding slit  46   b  (the fixing protrusion  34  can not enter the protrusion-sliding slit  46   b  in the J-slot  46 ) as shown in  FIG. 6B  and  FIG. 7 . Therefore, the socket  40  can not be rotated in the direction of engagement of the fixing protrusion  34  and the J-slot  46 , and an operator can recognize that the engagement between the engaging protrusion  26  and the J-slot  46  is incomplete. By again performing the operation to fit the socket  40  after correctly engaging the engaging protrusion  26  with the protrusion latching portion  46   c  in the J-slot  46  and correctly integrating the bulb  20  with the socket  40  anew, the socket  40  can be fixed to the socket fixture  40 . The socket  40  does not become fixed to the socket fixture  30  in a state where the engagement between the engaging protrusion  26  and the J-slot  46  is incomplete. 
   Furthermore, the outer periphery of the rear end portion of the socket  40  may be integrally covered with a detachable socket cover  50  made of synthetic resin, the outer periphery of which also may be provided with a plurality of fin-like protrusions  52  for a fingerhold. The socket  40  integrated with the bulb  20  becomes hot due to heat generated by the bulb  20 , and directly holding the socket  40  by hand may cause a burn injury. Therefore, by holding the socket cover  50  that integrally covers the bulb socket  40  and does not become hot, the socket  40  (bulb) can be attached or detached without fear of a burn injury. 
   Furthermore, the fin-like protrusions  52  on the outer periphery of the socket cover  50  are disposed at positions that can easily be held with, for example, the thumb, index finger, and middle finger, and thus operations such as attachment and detachment can be performed smoothly by holding the socket cover  50 . Therefore, even if a clearance between the lamp body  10  and a vehicle body to which the headlamp is attached is narrow, the bulb replacement work can be performed smoothly. 
   In addition, the socket  40  and the socket cover  50  are elastically integrated by being pressed in the axial direction, and can be separated easily by pulling both elements  40  and  50  in the axial direction. 
   Other embodiments may be within the scope of the following claims.