Compact Rail Mountable Fuse Holder

The invention relates to fuse holders and other electronic assemblies that include built-in mechanisms for attaching to rails.

So-called DIN rails are used for mounting fuse holders and other electronic assemblies that engage the edges of the rails Fuse holders, which are normally surface mounted, have been mounted on DIN rails via adapters that are connected to the fuse holders and in turn have mechanisms to engage the edges of the rails, e.g., as shown in U.S. Pat. Nos. 4,767,339 and 4,921,445. Some fuse holders have included integral lips for engaging rails (e.g., FIGS. 4-6 of U.S. Pat. No. 4,767,339), and other types of electronic devices have included built-in mechanisms for mounting on rails, e.g., U.S. Pat. Nos. 4,947,290; 4,926,149; 5,000,692; 4,268,108; 4,878,859; 4,018,413; and 4,900,275.

In one aspect, the invention features, in general, a fuse holder including an insulative housing having integral recesses which receive receiving portions of a rail and a sliding locking member that slides on the housing between a locked position in which the fuse holder is retained on the rail and a mounting position in which the fuse holder can be mounted on or removed from the rail. Contacts for electrically engaging a fuse are carried by the housing.

In preferred embodiments, the sliding locking member has a tool receiving slot used to move the sliding locking member from the locked to the mounting position.

In another aspect, the invention features, in general, a rail mounting assembly including a housing having integral recesses which receive portions of a rail and a sliding locking member that slides on the housing. The locking member is biased toward a locked position via a resilient, cantilevered tab of the locking member and is maintainable in a mounting position via snap-in engagement of an end of the tab with a notch on the housing.

In preferred embodiments, the cantilevered tab has an end portion that is generally perpendicular to a sliding axis and slides on an inclined surface of the housing. The tab also has a base portion that is generally parallel to the sliding axis and is flexibly movable in an opening in a bottom wall of the sliding locking member.

In another aspect, the invention features, in general, a rail mounting assembly including a housing having integral recesses which receive portions of a rail and a sliding locking member that slides on the housing between a locked position and a mounting position. The sliding locking member is made of a one-piece molded part that has two side walls that sit in a cavity space in the housing and have bent tops which form lips resting on recessed shelf surfaces of the housing.

In preferred embodiments, the upper surfaces of the side walls have curved outer surfaces, permitting resilient inward deflection of the side walls during assembly and outward movement of the lips after they have been moved beyond the recessed shelf surfaces.

Other features and advantages of the invention will be apparent from the following description of a preferred embodiment thereof and from the claims.

The drawings will be described first.

FIG. 1 is a perspective view of a fuse holder according to the invention shown mounted on a rail.

FIGS. 2 and 3 are side views, partially broken away, of the FIG. 1 fuse holder shown with its sliding locking member in a locked position and a mounting position, respectively.

FIG. 4 is a perspective view of the sliding locking member of the FIG. 1 fuse holder.

FIG. 5 is a plan view of the FIG. 4 sliding locking member.

FIG. 6 is a vertical sectional view, taken at 6--6 of FIG. 4, of the FIG. 4 sliding locking member.

FIG. 7 is a side elevation of the FIG. 4 sliding locking member.

FIG. 8 is a vertical sectional view, taken at 8--8 of FIG. 2, of the housing of the FIG. 1, fuse holder.

Referring to FIGS. 1 and 2, fuse holder 10 is shown mounted on DIN rail 12. Fuse holder 10 includes housing 14, sliding locking member 16, electrical contacts 18 (for engaging and making electrical contact with a fuse), and terminals 20 (for connecting to electrical wires). Edge portions 22, 24 of rail 12 (also referred to as "receiving portions") sit within integral recesses 26, 28 of housing 14. Edge portion 22 is engaged by facing upper and lower surfaces 30 and 32 at recess 26. Edge 24 is engaged by upper surface 34 at recess 28 and facing surface 36 of detent 38 of sliding locking member 16 when it is in the locked position shown in FIG. 2.

Referring to FIGS. 2-8, sliding locking member 16 (shown alone in FIG. 4) is slidably mounted on housing 14 along sliding axis 40 between a locked position (FIG. 2), in which fuse holder 10 is retained on rail 12, and a mounting position (FIG. 3), in which fuse holder 10 can be mounted on or removed from rail 12. Sliding locking member 22 has two side walls 42, 44 (FIGS. 4, 7) which travel in cavity 46 (FIG. 8) within housing 14. Side walls 42, 44 have bent tops which form lips 48, 50 that sit on recessed shelf surfaces 52, 54 of housing 14 (FIG. 8). The lower surfaces of lips 48, 50 are located 0.491" above the lower surface of bottom wall 53, the same distance that the shelf surfaces 52, 54 are above the bottom surface of housing 14. The upper surfaces of side walls 42, 44 have curved outer edges. Sliding locking member 16 has tool-receiving slot 56 in slotted end 58 that extends beyond housing 14.

Cantilevered tab 60 is located between detent 38 and slotted end 58 and has end portion 62, generally perpendicular to sliding axis 40, and perpendicular base portion 64, generally parallel with sliding axis 40 and connected at one end to bottom wall 53, which has open area 67 in which base portion 64 is flexibly movable. End 66 of end portion 62 slides along inclined surface 68 of housing 14. Surface 68 is oriented at an acute angle (preferably between 30.degree. and 60.degree., and most preferably about 45.degree.) with sliding axis 40 and has notch 70, which is engaged by end 66 of tab 60 by snap-in engagement. Notch 70 is defined by two surfaces, one that is parallel with axis 40 and is shorter in distance than the thickness of end 66, and one that is oriented at an angle of 80.degree. with axis 40. The first mentioned surface is located 0.448" above the lower surface of housing 14, while end 66 is located 0.512" above the lower surface of bottom wall 53. This difference in height causes a generally vertically directed force by end 66 against the upper surface of notch 70, causing sliding locking member 16 to be maintained in the mounting position when end 66 is in notch 70. This difference in height also causes a vertically directed force by end 66 against inclined surface 68, biasing sliding locking member 16 toward the locked position when end 66 has been moved out of notch 70.

Housing 14 also has central elongated slot 72 (one end of which is shown in FIG. 1) to permit attaching fuse holder 10 to a supporting substrate via screws or bolts. The flat nature of the bottom of housing 14 and the flush mounting of sliding locking member 16 facilitate such mounting.

Housing 14 and sliding locking member 16 are each made of a one-piece molded plastic part. In assembling fuse holder 10, sidewalls 42, 44 are inserted into cavity 46. The curved nature of the outer edges of the tops of side walls 42, 44 causes them to be resiliently deflected inward by the inner surfaces defining the sides of cavity 46. When lips 48, 50 are above recessed shelf surfaces 52, 54, they expand outward over surfaces 52, 54, locking sliding locking member in place. All that is required to complete assembly is to secure contacts 18 and terminals 20 on housing 14 via screws. Thus only a single additional plastic part is used to provide the fuse holder with a resilient locking member for mounting on a DIN rail, and the part is added to the fuse holder via a simple snap-in procedure.

In use, sliding locking member is moved to the mounting position (FIG. 3) by pulling slotted end 58 away from housing 14, either by engaging with fingers or with a screw driver in slot 56. Fuse holder 10 is maintained in the mounting position via snap-in engagement of end 66 of tab 60 with notch 70. Fuse holder 10 is then placed in position over rail 12, and slotted end 58 is pushed, moving end 66 beyond notch 70. The resulting interaction of upwardly-biased end 66 of tab 60 with inclined surface 68 results in biasing member 16 toward and into the locked position (FIG. 2).

Other embodiments of the invention are within the scope of the following claims.