U.S. patent number RE33,877 [Application Number 07/559,689] was granted by the patent office on 1992-04-07 for fuse block with rejection feature.
This patent grant is currently assigned to Cooper Industries, Inc.. Invention is credited to Gayle L. Sappington.
United States Patent |
RE33,877 |
Sappington |
April 7, 1992 |
Fuse block with rejection feature
Abstract
A rejection-type fuse block is disclosed for use with Class CC
cartridge-type fuses having ferrules at opposite ends, the ferrule
at one end having a cap of smaller diameter than the ferrule. An
insulated rejection collar having a rejection opening sized to
allow the cap to pass therethrough while preventing passage of the
ferrule is positioned between the fuse and an electrically
conductive terminal. A leaf spring located at the end of the fuse
opposite the cap end serves to axially press the fuse towards the
insulated rejection collar and the cap into contact with the
terminal. Fuse clips are provided for releasably securing the clip
in proper position.
Inventors: |
Sappington; Gayle L. (Glendale,
MO) |
Assignee: |
Cooper Industries, Inc.
(Houston, TX)
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Family
ID: |
27041070 |
Appl.
No.: |
07/559,689 |
Filed: |
July 26, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
464701 |
Feb 7, 1983 |
04761148 |
Aug 2, 1988 |
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Current U.S.
Class: |
439/831 |
Current CPC
Class: |
H01H
85/24 (20130101) |
Current International
Class: |
H01H
85/00 (20060101); H01H 85/24 (20060101); H01R
013/00 () |
Field of
Search: |
;439/620-622,680,831
;337/210,214,215,225,226,262 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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623638 |
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Dec 1935 |
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DE2 |
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2031235 |
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Apr 1980 |
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GB |
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Primary Examiner: McGlynn; Joseph H.
Attorney, Agent or Firm: Rose; David A.
Claims
What is claimed is:
1. A rejection fuse block for a cartridge-type fuse having
electrical contact elements at opposite ends, the contact element
at one end including a cap, said cap having a smaller
cross-sectional width than the adjacent portion of said fuse
contact element; said fuse block comprising:
(a) support means;
(b) electrically conductive means mounted on said support means and
having a surface for contacting said cap at said one end of said
fuse and making a first electrical connection with said fuse;
(c) electrically insulated rejection means colligated with said
surface of said electrically conductive means, said rejection means
having a rejection opening sufficiently large to pass said cap
portion therethrough into contact with said electrically conductive
means but smaller than the adjacent portion of said fuse contact
element to prevent passage therethrough of said adjacent
portion;
(c) means mounted on said support means for contacting the contact
element at the opposite end of said fuse to make a second
electrical connection with said fuse and for biasing said fuse
towards said electrically insulated rejection means to force said
cap into contact with said electrically conductive means; and
(d) dummy fuse clip means, said dummy clip means releasably
retaining said one end of said fuse such that said cap is in
alignment with said rejection opening in said rejection means, said
dummy clip means being electrically insulated from said
electrically conductive means.
2. The fuse block of claim 1 wherein said means for contacting the
contact element at the opposite end of said fuse and for biasing
said fuse towards said electrically insulated rejection means
comprises a fuse clip for releasably retaining said contact element
at the opposite end of said fuse and a leaf spring arranged to
contact said contact element at the opposite end of said fuse and
bias said fuse towards said electrically insulated rejection
means.
3. The fuse block of claim 1 wherein said electrically conductive
means having a surface for contacting said cap defines a pocket for
receiving said cap therein to provide an electrical connection.
4. The fuse block of claim 2 wherein said leaf spring is composed
of a material having a lower electrical conductivity characteristic
than that of said fuse clip. .Iadd.
5. A rejection fuse block for a cartridge-type fuse having
electrical contact elements at opposite ends, the contact element
at one end including a cap, said cap having a smaller
cross-sectional width than the adjacent portion of said fuse
contact element; said fuse block comprising:
(a) support means;
(b) electrically conductive means mounted on said support means and
having a surface for contacting said cap at said one end of said
fuse and making a first electrical connection with said fuse;
(c) electrically insulated rejection means colligated with said
surface of said electrically conductive means, said rejection means
having a rejection opening sufficiently large to pass said cap
portion therethrough into contact with said electrically conductive
means but smaller than the adjacent portion of said fuse contact
element to prevent passage therethrough of said adjacent
portion;
(d) means mounted on said support means for contacting the contact
element at the opposite end of said fuse to make a second
electrical connection with said fuse and for biasing said fuse
towards said electrically insulated rejection means;
(e) insulative guide means engageable with the adjacent portion to
center said gap with said electrically conductive means; and
(f) said electrically conductive means further including retention
means for providing a positive connection with the cap. .Iaddend.
.Iadd.
6. The rejection fuse block of claim 5 wherein said retention means
includes a pocket in said surface of said electrically conductive
means to positively connect the cap. .Iaddend. .Iadd.7. The
rejection fuse block of claim 5 wherein said guide means includes
an insulative stop engageable with the adjacent portion to limit
the movement of the cap towards said support means and opposing
insulative sides engageable with the adjacent portion for the
centering of the cap. .Iaddend. .Iadd.8. A rejection fuse block for
a cartridge-type fuse having a rejection terminal on one end and a
non-rejection terminal at the other end, the rejection terminal
having a cap with a smaller cross-sectional width than the adjacent
portion of the rejection terminal, said fuse block comprising:
an insulating support base;
a first electrically conductive means mounted on said support base
and having an electrical contact for contacting the cap and making
a first electrical connection with the fuse;
an electrically insulated rejection member adjacent said electrical
contact, said rejection member having an opening sufficiently large
to pass the cap therethrough into contact with said electrical
contact but smaller than the adjacent portion of the fuse rejection
terminal to prevent passage therethrough of the adjacent
portion;
a second electrically conductive means mounted on said support base
for contacting the non-rejection terminal of the fuse to make a
second electrical connection with the fuse;
biasing means mounted on said support base for biasing the adjacent
portion of the fuse rejection terminal against said electrically
insulated rejection member;
insulative alignment means engaging opposite sides of the adjacent
portion for centering the cap with said electrical contact; and
said electrical contact having a pocket to retain the cap.
.Iaddend.
.Iadd. . The rejection fuse block of claim 8 wherein said
rejection
member is made of a dielectric material. .Iaddend. .Iadd.10. The
rejection fuse block of claim 8 wherein said second electrically
conductive means is a fuse clip releasably retaining the
non-rejection terminal. .Iaddend. .Iadd.11. The rejection fuse
block of claim 8 wherein said opening is aligned with said pocket.
.Iaddend. .Iadd.12. The rejection fuse block of claim 8 wherein
said alignment means also retains the adjacent portion. .Iaddend.
.Iadd.13. The rejection fuse block of claim 8 wherein said
rejection member spaces the cap from said electrical
contact. .Iaddend. .Iadd.14. The rejection fuse block of claim 8
wherein said insulative alignment means is made of metal and is
electrically insulated from said first electrically conductive
means. .Iaddend.
.Iadd. . The rejection fuse block of claim 14 wherein said metal
alignment means acts as a heat sink to dissipate excess heat
generated by the fuse. .Iaddend. .Iadd.16. The rejection fuse block
of claim 8 wherein said biasing means is a leaf spring. .Iaddend.
.Iadd.17. The rejection fuse block of claim 16 wherein said leaf
spring is made of a material with an electrical resistance high
enough to sufficiently reduce current flow therethrough to prevent
stress relaxation in said leaf spring. .Iaddend. .Iadd.18. A
fuseholder for a fuse having a rejection ferrule on one end and a
non-rejection ferrule on the other end, the rejection ferrule
having a cap arranged concentrically with the rejection ferrule and
having a smaller diameter than the rejection ferrule,
comprising:
an insulative base;
an electrically conductive contact mounted and projecting from one
end of said base and having a pocket for receiving and retaining
the cap for making a first electrical connection with the fuse;
an electrically conductive fuse clip mounted and projecting from
the other end of said base for receiving and retaining the
non-rejection ferrule and for making a second electrical connection
with the fuse;
an insulative member projecting from said base between said fuse
clip and contact, said member having an opening aligned with said
pocket for receiving the cap but not the rejection ferrule;
biasing means adjacent said fuse clip for axially biasing the
rejection ferrule against said insulative member;
an insulative stop projecting from said base engageable with the
rejection ferrule for limiting the movement of the rejection
ferrule towards said base; and
centering means projecting from said base engageable with the
rejection ferrule for centering the cap with said opening and
contact. .Iaddend.
Description
BACKGROUND OF THE INVENTION
Standards for fuses in the United States provide for different
interrupting capacity fuses having generally the same exterior
dimensions, specifically length and diameter. In such cases it is
the practice to provide a rejection feature in both the fuses and
the fuse blocks such that in the case of like dimension fuses,
those having a lower interrupting capacity are prevented from being
inserted in a fuse block specifically designed for those having a
higher interrupting capacity. For example, one form of rejection
feature well known in the art is to use ferrule-type fuses with an
annular groove in the ferrule at one end of the fuse. Various fuse
blocks are known in the art which will accept a fuse of
predetermined higher interrupting capacity but will reject a fuse
of like dimension but of lower interrupting capacity. Examples of
this type of fuse block are disclosed in U.S. Pat. Nos. 4,257,662
to Matten, 4,097,114 to Matten, 3,960,435 to Bailey et al. and
4,178,063 to Reynolds.
Another form of rejection feature is provided for Class CC fuses in
which one end of a fuse is configured with a ferrule having a
concentric cap of lesser dimension than the ferrule. A fuse having
this form of rejection feature and a fuse clip for accepting fuses
with this feature while rejecting other tpes of fuses are disclosed
in U.S. Pat. No. 3,585,558 to Swain which teaches the use of a fuse
block having a pair of spaced fuse clips with rejection abutments.
Also of interest is the Underwriters Laboratory standard for Class
CC Fuseholder Ferrule Contact-Type Rejection Member, UL 512, as
described at page 8D therein. In accordance with the Underwriters
Laboratory standard a fuse clip with end stops is used in
combination with a rejection stop and terminal. A disadvantage of
both the Swain and Underwriters Laboratory arrangements is that the
dimensional tolerance of the overall length of the fuse and the
fuse block must be carefully controlled. A further disadvantage of
the Swain arrangement is that while it prevents the insertion of
the incorrect fuse, it allows electrical contact during an attempt
to insert an incorrect fuse.
SUMMARY OF THE INVENTION
The fuse block of the present invention is for use with Class CC
fuses and having a rejection feature. In accordance with the
invention the fuse block is provided with an insulating column
designed to act as a rejection spacer between the concentric cap of
the ferrule on one end of the fuse and the electrical contact
terminal of the fuse block. The fuse is positioned and retained in
electrical contact by means of a retaining leaf spring which
applies pressure to the fuse in the direction of the contact
terminal. This novel arrangement substantially reduces the
requirement of tight dimensional tolerance control.
An object of the present invention is to provide a fuse block with
rejection means for use primarily with Class CC fuses.
A further object of the present invention is to provide a rejection
fuse block which prevents electrical contact upon insertion of an
improper fuse.
Another object of the present invention is to provide a
rejection-type fuse block allowing greater dimensional
tolerance.
Still another object of the present invention is to provide a
rejection-type fuse block including means for applying pressure to
the fuse in the direction of the contact terminal.
Yet another object of the present invention is to provide a fuse
block with both rejection and retention features in which the
retention means is not subjected to heating due to heavy current
flow.
Other objects and features of the present invention will become
apparent with reference to the accompanying drawings and
description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a Class CC cartridge-type fuse;
FIG. 2 is a side view of a fuse block of the present invention;
FIG. 3 is a detailed view, partially in cross-section, of the
rejection means of the fuse block of FIG. 2;
FIG. 4 is an end view of the rejection end dummy fuse clip of the
fuse block of FIG. 2;
FIG. 5 is an end view of the non-rejection end fuse clip of the
fuse block of FIG. 2;
FIG. 6 is a perspective view of the rejection collar of the fuse
block of FIG. 2; and
FIG. 7 is a perspective view of the rejection end terminal of the
fuse block of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
The rejection feature of a Class CC fuse can be understood by
reference to FIG. 1. As shown, the Class CC fuse comprises a
non-rejection terminal 10 in the form of a ferrule which is well
known in the fuse art, a body portion 12 in which the fusible
element is contained, and a rejection end terminal having the form
of a ferrule 14 with a cap 16. Cap 16 is arranged concentric to
ferrule 14 and is of similar diameter than ferrule 14. The ferrule
14 with cap 16 provides the rejection feature.
FIG. 2 illustrates the features of the fuse block of the present
invention. A Class CC fuse is depicted inserted into a fuse block
constituting a preferred embodiment of the present invention. The
non-rejection terminal 10 is held by fuse clip 20, and axial
pressure is applied to the same terminal by leaf spring 34. Both
the fuse clip 20 and leaf spring 34 are positioned on a conductor
element 24 and secured in place on a fuse block base 18 by rivet or
screw 42. Both the fuse clip 20 and leaf spring 34 are connected to
an electric circuit by means of terminal screw 32. However, the
leaf spring 34 preferably has a high electrical resistance such
that current flow in the leaf spring is minimal. The high
electrical resistance of leaf spring 34 assures that the leaf
spring will not experience stress relaxation caused by heat
generated by high current flow which would tend to reduce contact
pressure at the rejection end terminal cap 16.
Rejection end ferrule 14 is held by a clip 22, termed a "dummy
clip" since the clip is not arranged for electrical current to flow
therethrough. Clip 22 is secured to base 18 by rivet 40. The
function of dummy clip 22 is to hold the ferrule 14 in proper
alignment on the base 18 and to center the ferrule with respect to
a rejection opening 36 in rejection collar 26. Clip 22 further
functions to drain heat from the Class CC fuse.
Rejection end terminal 28, which may be connected into an electric
circuit by screw 30, provides electrical connection to the Class CC
fuse via contact with cap 16 which is forced through rejection
opening 36 in rejection collar 26 into contact with terminal 28 by
the axial pressure applied by leaf spring 34. Rejection collar 26,
located adjacent to and in contact with terminal 28, is composed of
electrically insulating material thereby preventing a fuse from
making electrical contact unless the fuse is of the Class CC-type
with a cap 16 of sufficiently small cross-section to pass through
the rejection opening 36. Thus, even though a non-Class CC fuse can
be inserted into the fuse block of the present invention, the
non-Class CC fuse will not close the circuit due to the presence of
insulating rejection collar 26.
Normally, prior art fuse clips have stops to position fuses.
Therefore, the manufacturing tolerance in the overall length of the
fuse and in the lateral separation of the clips is critical. In the
present invention, stops are not required either in fuse clip 20 or
in dummy clip 22 since the axial positioning of the fuse is
controlled by leaf spring 34, terminal 28 and rejection collar 26.
Leaf spring 34 is designed to provide sufficient pressure on a
minimum length fuse and to not take a permanent set when the fuse
is at the maximum allowed length.
Details of the rejection end assembly of the present invention,
namely, the dummy clip 22, rejection collar 26, terminal 28, and
fuse rejection end terminal comprising ferrule 14 and cap 16, is
shown partially in cross-section in FIG. 3. Cap 16 is forced
through rejection opening 36 in rejection collar 26 and into
contact with terminal 28 in a pocket 38 in the terminal. Rejection
collar 26 can be secured to base 18 by any of several known means
without departing from the spirit of the invention since rejection
collar 26 is effectively colligated with terminal 28 and is
supported against lateral pressure by terminal 28. The collar 26
may be secured to the base 18 by adhesive, or alternatively the
collar 26 may be molded as an integral part of the base 18.
FIG. 4 is an end view of dummy clip 22 with an inserted Class CC
fuse. Ferrule 14 and concentric cap 16 are positioned by clip 22 to
align cap 16 with rejection opening 36 as shown in FIG. 3.
FIG. 5 is an end view of non-rejection end clip 20. Ferrule 10 is
positioned by clip 20. Due to pressure from leaf spring 34, shown
in FIG. 2, no stops to control axial positioning of the fuse are
required in clip 20.
Perspective views of rejection collar 26 and rejection end terminal
28 are shown in FIGS. 6 and 7 respectively. Rejection opening 36 is
sized to pass cap 16 as shown in FIGS. 2 and 3 but to prevent the
passage of ferrule 14. Terminal 28 includes pocket 38 for providing
a positive connection for cap 16 as shown in detail in FIG. 3. In
the preferred embodiment of the present invention, rejection collar
26 and terminal 28 are arranged in an effectively colligated manner
as shown in FIG. 3.
While the preferred embodiment of the present invention is
described herein, it should be understood that modifications
thereof are within the scope and spirit of the invention disclosed
and claimed.
* * * * *