Central wiring unit

Abstract: A central wiring unit (10) for a motor vehicle comprising a housing (12) of electrically insulating material and having a top wall (22), a bottom wall (24), and an open end (32); a drawer (14) of electrically insulating material which is slidable into the housing through the open end thereof; first snap fitting means (34,36) on the drawer and on the housing for holding the drawer inside the housing in a first position relative to the housing; second snap fitting means (38,40,42) on the drawer and on the housing for holding the drawer inside the housing in a second position relative to the housing; through bores (44) in the housing which open through the top wall and the bottom wall and which are alignable with corresponding through bores (46) in the drawer; an inwardly facing lip (48,50) in each through bore, the inwardly facing lips allowing insertion and removal of an electrical terminal in each corresponding through bores through the bottom wall of the housing in the first position of the drawer relative to the housing, and retarning the electrical terminal in the second position of the drawer relative to the housing; and a control unit (16) slidable into an open ended channel (60) in the drawer through the open end of the housing when the drawer is in the second position relative to the housing, the control unit engaging the second snap fitting means to prevent release of the second snap fitting means. Improved central wiring unit.

Description: Technical Field The present invention relates to a central wiring unit for a motor vehicle. Background of the Invention The central wiring unit of a motor vehicle generally comprises a housing of electrically insulating material, the housing containing a number of through bores within which are positioned electrical terminals. The terminals are connected to at least a part of the wiring harness of the motor vehicle. Fuses, relays, and other electrical components are plugged into the terminals. After insertion of the terminals in the through bores, additional keying elements are required to lock each terminal in each through bore. A central wiring unit according to the preamble of claim 1 is disclosed in EP-A-0584592. Summary of the Invention It is an object of the present invention to provide an improved central wiring unit. A central wiring unit in accordance with the present invention for a motor vehicle comprises a housing of electrically insulating material and having a top wall, a bottom wall, and an open end; a drawer of electrically insulating material which is slidable into the housing through the open end thereof; first snap fitting means on the drawer and on the housing for holding the drawer inside the housing in a first position relative to the housing; second snap fitting means on the drawer and on the housing for holding the drawer inside the housing in a second position relative to the housing; through bores in the housing which open through the top wall and the bottom wall and which are alignable with corresponding through bores in the drawer; an inwardly facing lip in each through bore, the inwardly facing lips allowing insertion and removal of an electrical terminal in each corresponding through bores through the bottom wall of the housing in the first position of the drawer relative to the housing, and retaining the electrical terminal in the second position of the drawer relative to the housing; and a control unit slidable into an open ended channel in the drawer through the open end of the housing when the drawer is in the second position relative to the housing, the control unit engaging the second snap fitting means to prevent release of the second snap fitting means. The central wiring unit of the present invention provides a retaining arrangement for the electrical terminals without the need for additional keying elements. Brief Description of the Drawings The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is an exploded view of a central wiring unit in accordance with the present invention; Figure 2 is an end view of one end of the housing of the central wiring unit of Figure 1; Figure 3 is a bottom view of the control unit of the central wiring unit of Figure 1; Figure 4 is a top view of part of the drawer of the central wiring unit of Figure 1; Figure 5 is a cross-sectional view on the line V-V of Figure 4; Figure 6 is a bottom view of part of the housing of the central wiring unit of Figure 1; Figure 7 is a cross-sectional view on the line VII-VII of Figure 6; and Figure 8 is a cross-sectional view on the line VIII-VIII of Figure 4. Description of the Preferred Embodiment Referring to the drawings, a central wiring unit 10 in accordance with the present invention comprises a housing 12, a drawer 14, and a control unit 16, and preferably a cover 18 and a hinge 20. The housing 12 is preferably moulded from electrically insulating material and comprises a top wall 22, a bottom wall 24, a first side wall 26, a second side wall 28, and an end wall 30. The other end 32 of the housing 12 is substantially open. The drawer 14, which is preferably moulded from electrically insulating material, is shaped and sized to make a sliding fit into the housing 12 through the open end 32 of the housing. The drawer 14 has a pair of resilient tabs 34 which, on sliding the drawer into the housing 12, make a snap fit in corresponding apertures 36 in the top wall 22 of the housing, to retain the drawer in a first positioned relative to the housing. The drawer 14 also has a flexible flap 38 with an outwardly directed rib 40 which makes a snap fit in a corresponding aperture 42 in the bottom wall 24 of the housing 12, to retain the drawer in a second position relative to the housing. On sliding the drawer 14 into the housing 12 in the direction X, the drawer initially reaches the first position. Further relative movement in the direction X moves the drawer 14 from the first position to the second position. The apertures 36 are sized to allow movement of the tabs 34 whilst the drawer 14 moves from the first position to the second position relative to the housing 12. Removal of the drawer 14 from the housing 12 requires the use of a special tool (not shown) to release the resilient tabs 34 from the apertures 36, and the drawer 14 can be slid out of the housing 12 by pushing the drawer through an aperture 94 in the end wall 30 of the housing. The housing 12 has a number of through bores 44 which open through both the top wall 22 and the bottom wall 24. The drawer 14 has corresponding through bores 46. The through bores 44,46 extend axially in a direction which is perpendicular to the direction X. When the drawer 14 is in the first position relative to the housing 12, the corresponding through bores 44,46 are slightly offset. When the drawer 14 is in the second position relative to the housing 12, the corresponding through bores 44,46 are substantially aligned. Despite the slight offset of the corresponding bores 44,46 when the drawer 14 is in the first position relative to the housing 12, electrical terminals (not shown), which are connected to the ends of electrical conductors (not shown) of a vehicle wiring harness (not shown), can be inserted into, and removed from, the corresponding through bores 44,46, through the bottom wall 24 of the housing. When the drawer 14 is in the second position relative to the housing 12, the electrical terminals are secured in the aligned through bores 44,46 and cannot be removed, as explained below. The through bores 46 in the drawer 14 have inwardly facing lips 48 at the ends of the through bores which are adjacent the top wall 22 of the housing 12. The through bores 44 in the housing 12 have inwardly facing lips 50 in the portion of the through bores opening through the bottom wall 24. In the first position of the drawer 14 relative to the housing 12, the lips 50 are offset from the through bores 46 in the drawer 14. However, in the second position of the drawer 14 relative to the housing 12, the lips 50 project across one end of the through bores 46 in the drawer 14. As a consequence, the electrical terminals in the through bores 44,46 are trapped between the pairs of lips 48,50 in the corresponding through bores 44,46. The positioning of the lips 48,50 within each corresponding through bore 44,46 is determined to provide a predetermined axial separation between the lips, each axial separation being dependent on the shape and size of the electrical terminal to be positioned within each corresponding through bore 44,46. The control unit 16 comprises a main unit 52 and a unit cover 54. The main unit 52 houses one or more electronic control devices (not shown), such as a multitimer, and electrical terminals (not shown) associated with the control device(s) positioned in bores 70 in the main unit. The unit cover 54 has a number of flexible tabs 56 which make a snap fit on corresponding lips 58 formed on the main unit 52. The drawer 14 has a channel 60 formed therein which extends axially in the same direction as the direction X, the channel having an open top 62 and an open end 64. The open top side 62 of the channel 60 is closed by the top wall 22 of the housing 12 when the drawer 14 is positioned in the housing. The open end 64 of the channel 60 aligns with the open end 32 of the housing 12 when the drawer 14 is positioned in the housing. The flap 38 in the drawer 14 is formed in the base 66 of the channel 60. The control unit 16 slides in the direction X through the open end 64 into the channel 60. When the drawer 14 is in the first position relative to the housing 12, the rib 40 on the flap 38 engages the base 66 of the channel 60 to deflect the free end 68 of the flap into the channel to prevent the control unit 16 being slid into the channel. When the drawer 14 is in the second position relative to the housing 12, the rib 40 on the flap 38 snap fits in the aperture 42 in the bottom wall 24 of the housing and the flap lies in substantially the same plane as the base 66 of the channel to allow the control unit 16 to be slid into the channel in the direction X. When the control unit 16 has been slid into the channel 60, the control unit prevents the flap 38 from moving, and so the drawer 14 remains fixed in the housing 12 due to the rib 40 being retained in the aperture 42. Also, when the control unit 16 has been slid into the channel 60, the bores 70 in the main unit 52 align with apertures 72 in the top wall 22 of the housing 12. The control unit 16 may be slid out of the channel 60 by pushing the control unit through aligned apertures 74,76 in the drawer 14 and the end wall 30 of the housing 12, respectively. For ease of insertion of the control unit 16 into the channel 60, the base 66 of the channel has two grooves 78 formed therein which are substantially parallel and extend in the direction X from the open end 64 of the channel. The unit cover 54 of the control unit 16 has a corresponding pair of ribs 80 which make a sliding fit in the grooves 78. Each groove 78 preferably has pimple 82 formed therein which makes a snap fit in a corresponding depression 84 in the corresponding rib 80 when the control unit 16 is fully inserted in the channel 60 in the drawer 14. The cover 18 has resilient tangs 86, four of which make a snap fit in open ended slots 88 in the end wall 30 of the housing 12, the others making a snap fit in open ended slots 90 formed in the drawer 14 adjacent the open end 32 of the housing. The slots 88,90 extend axially in the same axial direction as the through bores 44,46 in the housing 12 and the drawer 14. The cover 18 makes a snap fit in the housing 12 and the drawer 14 when the drawer is in the first position or the second position relative to the housing to substantially cover the bottom wall 24 of the housing. When in place, the cover 18 prevents withdrawal of the drawer 14 from the housing 12. The cover has an aperture 92 through which the cable harness (not shown) can pass, and may be shaped to bend the cable harness in a required direction. The resilient tangs 86 prevent the cover 18 being pushed off by the cable harness. The hinge 20 makes a sliding snap fit on the second side wall 28 of the housing 12. The hinge 20 provides means for mounting the central wiring unit 10 in a motor vehicle, with the central wiring unit being pivotable between a storage position and an access position for maintenance purposes. The present invention is not restricted to the above described embodiment. For example, other suitable arrangements may be provided for the snap fit of the drawer 14 and the housing 12 in the first position and/or the snap fit in the second position, and the positioning of the snap fit in the first position may be other than that shown in the drawings.

Claims: A central wiring unit (10) for a motor vehicle comprising a housing (12) of electrically insulating material and having a top wall (22), a bottom wall (24), and an open end (32); a drawer (14) of electrically insulating material which is slidable into the housing through the open end thereof; through bores (44) in the housing which open through the top wall and the bottom wall and which are alignable with corresponding through bores (46) in the drawer; characterized in that the central wiring unit (10) furter comprises first snap fitting means (34,36) on the drawer and on the housing for holding the drawer inside the housing in a first position relative to the housing; second snap fitting means (38,40,42) on the drawer and on the housing for holding the drawer inside the housing in a second position relative to the housing; in inwardly facing lip (48,50) in each through bore, the inwardly facing lips allowing insertion and removal of an electrical terminal in each corresponding through bores through the bottom wall of the housing in the first position of the drawer relative to the housing, and retaining the electrical terminal in the second position of the drawer relative to the housing; and a control unit (16) slidable into an open ended channel (60) in the drawer through the open end of the housing when the drawer is in the second position relative to the housing, the control unit engaging the second snap fitting means to prevent release of the second snap fitting means. A central wiring unit as claimed in Claim 1, wherein the second snap fitting means (38,40,42) prevents insertion of the control unit (16) into the open ended channel (60) when the drawer (14) is in the first position relative to the housing (12). A central wiring unit as claimed in Claim 1 or Claim 2, wherein the open ended channel (60) has a base (66) adjacent the bottom wall (24) of the housing (12); and wherein the second snap fitting means comprises a flexible flap (38) formed in the base of the open ended channel, and an aperture (42) in the bottom wall of the housing, the flap having an outwardly directed rib (40) which makes a snap fit in the aperture when the drawer (14) is in the second position relative to the housing. A central wiring unit as claimed in any one of Claims 1 to 3, wherein the first snap fitting means comprises a resilient tab (34) formed on the drawer (14) and an aperture formed in the top wall (22) of the housing (12), the tab making a snap fit in the aperture (36) when the drawer is in the first position relative to the housing. A central wiring unit as claimed in any one of Claims 1 to 4, wherein the open ended channel (60) has grooves (78) formed therein which extend in the sliding direction of the control unit (16) relative to the drawer (14) to the open end (64) of the channel; and wherein the control unit has corresponding ribs (80) which make a sliding fit in the grooves. A central wiring unit as claimed in Claim 5, wherein each groove (78) has a pimple (82) which makes a snap fit in a corresponding depression (84) in the corresponding rib (80) on full insertion of the control unit (16) in the open ended channel (60). A central wiring unit as claimed in any one of Claims 1 to 6, further comprising a cover (18) which makes a snap fit with the drawer (14) and the housing (12) when the drawer is in the first position or the second position relative to the housing, the cover substantially covering the bottom wall (24) of the housing. A central wiring unit as claimed in Claim 7, wherein the cover (18) has resilient tangs (86) which make a snap fit in corresponding slots (88,90) in the drawer (14) and the housing (12). A central wiring unit as claimed in any one of Claims 1 to 8, further comprising a hinge (20) which makes a snap fit on a side wall (28) of the housing (12).

Inventors: DEVEAUX AXEL, FISCHER HARALD, KOBURG DIRK, SPIESS OLIVER, DEVEAUX, AXEL, FISCHER, HARALD, KOBURG, DIRK, SPIESS, OLIVER
Applicants: DELPHI AUTOMOTIVE SYSTEMS GMBH, DELPHI AUTOMOTIVE SYSTEMS DEUTSCHLAND GMBH
Application year: 1998
Main classification: B60R16
IPC codes: B60R16