The field of the invention relates generally to fuse holders for electrical fuse circuit protection devices, and more specifically to fuse clip assemblies for establishing line and load side electrical connections to terminal elements of overcurrent protection fuses.
Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source or power supply and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current flow through the fuse exceeds a predetermined limit, the fusible elements melt and opens one or more circuits through the fuse to prevent electrical component damage.
Fuse terminals in the form of resilient clips are known and in widespread use with various types of fuse holders in which the electrical fuses may be removed and replaced while leaving the line and side electrical connections to the fuse holder in place. The resilient clips may be configured to receive and establish mechanical and electrical connection with terminal elements provided on the fuse, such as cylindrical end caps or ferrules, or as another example terminal blade contacts extending from the housing of the fuse. The resilient fuse clip terminals provided in the fuse holders therefore grip corresponding terminal elements of the fuse and provide a contact force to ensure adequate mechanical and electrical connection therebetween.
While resilient fuse clip terminals have been effective to establish mechanical and electrical connections to and through fuses, they can be problematic in some aspects and improvements are desired.
Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified.
In conventional fuse clip assemblies, springs are sometimes used to provide additional contact pressure with terminal elements of a fuse. Known springs are provided to resist outwardly directed pressure tending to expand the fuse clips and receive a terminal element of the fuse. Except for the mechanical properties of the clips themselves, no features are provided in conventional fuse clips to resist inwardly directed pressure on the fuse clips tending to compress the fuse clips. At times, the mechanical properties of the fuse clips are insufficient to prevent damage to the fuse clips when subjected to compression forces, and improvements are desired.
Exemplary embodiments of fuse holders and fuse clip assemblies therefor are described below that beneficially provide support to the fuse clips not only when expanded, but when compressed. Thus, instead of supporting the fuse clips in a single direction tending to expand the clips as in conventional fuse clip assemblies, the exemplary embodiments disclosed herein support the fuse clip in dual directions both tending to expand the clips as well as compressing them. Method aspects will be in part apparent and in part specifically discussed in the description below.
In the example depicted, the fuse holder 100 includes a generally elongated base 106 fabricated from an electrically nonconductive or insulative material, and upstanding side walls 108a, 108b extending from the opposing lateral edges 109a, 109b of the base 106. The fuse clip assemblies 102a, 102b are attached to the base 106 at respective locations between the walls 108a, 108b via a fastener 110a, 110b such as a screw, a rivet, or other fasteners and fastening techniques known in the art. Openings 112 are centrally located between the side walls 108a, 108b to facilitate installation and removal of the fuse 104. The side walls 108a, 108b provide lateral barriers atop the base 106, however, and effectively prevent or preclude inadvertent contact with the fuse clip elements 102a, 102b from the lateral direction. The longitudinal ends 113a, 113b of the base 106, however, are open or unobstructed to facilitate connection to electrical conductors such as wires 112, 114 (
The fuse clip assemblies 102a, 102b (also shown in
The fuse 104 in the embodiment shown generally includes a cylindrical or tubular body 128 fabricated from an electrically nonconductive or insulative material, and electrically conductive terminal elements 130a, 130b coupled to the opposed axial ends of the fuse body 128. A fuse element 132 (shown in phantom in
In the example shown, the terminal elements 130a, 130b are cylindrical elements that may be recognized by those in the art as “end caps” or “ferrules.” In further and/or alternative embodiments, the fuse 104 may further include contact blades, sometimes referred to as knife blades, projecting from the axial ends of the terminal elements 130a, 130b. The fuse 104 as shown, however, is provided solely for the sake of illustration rather than limitation, and other types of fuses may accordingly be utilized, including but not limited to rectangular fuse modules having spaced apart terminal blade contacts extending from a common side of a rectangular fuse housing. Such rectangular fuse modules are commercially available from Cooper Bussmann of St. Louis, Mo. and are known in the art as CUBEFuse® power fuses. Any fuse compatible with the fuse clip elements as described below, however, may be suitable for use a fuse holder with appropriate modification.
As best shown in
Current flows from the line side circuitry 116 through the conductor 112 and to the connection portion 120a of the fuse clip assembly 102a. From the connection portion 120a current flows through the anchor portion 124a to the fuse clip portion 122a. From the fuse clip portion 122a current flows to the fuse terminal element 130a, to the fuse element 132 and to the other fuse terminal element 130b. From the fuse terminal 130b current flows through the fuse clip portion 122b of the fuse clip assembly 102b. From the fuse clip portion 122b, current flows to and through the anchor portion 124b to the connection portion 120b. From the connection portion 120b current flows through the conductor 114 to the load side circuitry 118.
Fusible protection to the line side circuitry 118 is provided via operation of the fuse element 132. When the fuse element 134 opens, electrical component damage to load side circuitry is avoided as the fuse effectively isolates problematic electrical circuit conditions in the line side circuitry 116 from being passed to the load side circuitry 118. To restore operation of the load side circuitry 118, the fuse 104 must be removed and replaced after it has opened. The openings 112 in the base walls 108a, 108b facilitates fuse installation and removal by providing clearance for a person's fingers to grasp the body 128 of the fuse 104 for installation or removal from the fuse holder 100, or alternatively to provide clearance for a fuse removal tool, sometimes referred to as a fuse puller, that may likewise engage the body 128 of the fuse 104 for its installation or removal.
The fuse holder 100 depicted in
Additionally, while the fuse holder 100 shown in
The connection portion 120a includes a pair of upstanding flanges or tabs 150 extending from the opposing lateral side edges 152, 154 of the square section 140 and defining the connection portion 120a. The tabs 150 may include chamfered distal ends as shown in
The rectangular section 142 of the anchor portion 124a in the example shown includes opposing lateral edges 158, 160 that are inset from or inwardly spaced from the lateral edges 152, 254 of the square section 140. In other words, the dimensional distance from lateral edge 158 to lateral edge 160 of the rectangular section 142 is smaller than a dimensional distance from lateral edge 152 to lateral edge 154 of the square section 140. A pair of resilient clip arms 162 extends upwardly from each of the lateral side edges 158, 160 of the rectangular section 142 in a spaced relation from the tabs 150 and define the clip portion 122a of the fuse clip assembly 102a. The clip arms 162 and the tabs 150 are spaced longitudinally from one another along an axis of the assembly extending between the opposing longitudinal edges 163, 165 of the anchor portion 124a.
As best seen in
The distal ends of the clip arms 162 each include flared sections 170 that extend in a spaced part, but generally parallel relationship to the anchor portion 124a in a relaxed or resting position shown in
The fuse clip arms 162 may be fabricated as integral pieces of conductor material that are formed or bent out of the plane of the rectangular section 142 of the anchor portion 124a. In the example shown, the fuse clip arms 162 are generally inset from the tabs 150 of the connector portion 120a. That is the fuse clip arm sections 164 and 168 are spaced apart in a lateral direction by an amount less than the tabs 150 are spaced apart. The flared sections 172 of the fuse clip arms 162 extend outwardly and the distal ends thereof are spaced apart by a distance approximately equal to the distance by which the tabs 150 are spaced apart.
As best shown in
The bias element 180 in contemplated embodiments is separately fabricated from the fuse clip arms 162 and provides dual directional support to the fuse clip arms 162 that is advantageous for the reasons discussed below. The bias element 180 may be fabricated from conductive or nonconductive materials as desired. As seen in
Once the bias element 180 is assembled to the fuse clip arms 162 to complete the fuse clip assembly 102a, the arrangement shown in
In conventional fuse clip assemblies, otherwise similar bias elements for the fuse clip arms may become mechanically uncoupled from the fuse clips when they are subjected to compression forces, and thus fail to provide any support to the fuse clip arms in such a condition. Conventional fuse clip assemblies are thus prone undesirable deformation when subjected to compression forces, while the fuse clip assembly 102a is comparatively much stronger and less likely to be deformed or damaged as a result of compression forces. Compression forces may inadvertently result in a variety of ways during manufacturing, shipping, handling, installation and even maintenance procedures of the fuse holder in use.
In contrast to a conventional retaining spring of conventional fuse clips, which support the fuse clip arm only in a single direction when subjected to external force, namely when a fuse is inserted into the clips and the clips expand out, the fuse clip assembly 102a including the bias element 102a not only supports the fuse clip arms 162 against when expanded as shown in
For example, the fuse clip arms 162 (and also the associated anchor portion 124a when the arms 162 are integral with the anchor portion) can be reduced in weight, size and/or cost by using thinner and/or softer more flexible materials. The fuse clip arms 162, because of the dual directional support of the bias element 180, need not be as structurally strong as in conventionally provided fuse clips. In certain instances, this may facilitate a reduction in size of the overall fuse holder as well as a reduction in size and cost of the fuse clips.
Manufacturing advantages also accrue as the fuse clips are less likely to be deformed during manufacturing processes. Shipping, transit, and distribution of the fuse holder is also less likely to result in deformed fuse clips.
Conventional fuse clips are typically able to withstand some amount of inward deflection due to their own mechanical properties, but it is not difficult to exceed the natural strength of the fuse clips against inward deflection, which sometime can occur inadvertently in the field, especially in open-style fuse holders such as the fuse holder 104 wherein the fuse clips are exposed and unprotected from the top and ends of the fuse holder. The extra strength provided by the positive engagement of the bias element ends 180 and the slots 172 of the fuse clip arms 162 is much less likely to be exceeded, and the associated problems are avoided.
If the fuse clip arms were to deform under compressive load, as conventional fuse clips are vulnerable to, greater mechanical stress in the fuse clip may result with a greater chance of fatigue failure as the fuse holder is used. By avoiding deformation under compressive loads, any premature failure of the fuse clip because of such deformation, and also any associated perception that the fuse holder may be of low quality is avoided. A longer working life of the fuse holder 100 is therefore made possible in many instances, particularly with respect to fatigue resistance.
Even if not problematic from a mechanical stress perspective, in open-style fuse holders such as the fuse holder 104 wherein the fuse clips are visible, even the appearance of a deformed fuse clip can be perceived as an indication of poor quality of the fuse holder. The dual directional support of the bias element 180 in the fuse clip assembly 102a not only avoids an impression of lower quality, but actually improves the quality of the fuse holder 100 by avoiding deformation of the fuse clip arms 162 altogether when subjected to compressive force.
The benefits and advantages of the inventive concepts disclosed are now believed to have been amply illustrated and are evident in the exemplary embodiments disclosed.
A fuse clip assembly for establishing an electrical connection to an overcurrent protection fuse including a conductive terminal has been disclosed. The fuse clip assembly includes: a pair of resilient fuse clip arms adapted to engage and retain the conductive terminal of the fuse; and a bias element coupled to the pair of resilient fuse clip arms, the bias element configured to resist deformation of the pair of resilient fuse clip arms when subjected to a compressive force and configured to support the pair of resilient fuse clip arms when subjected to an expansion force.
Optionally, the pair of resilient fuse clip arms each may include a respective slot, and a portion of the bias element extends through each respective slot of the pair of resilient fuse clip arms. The bias element may include a pair of resilient arms, and each of the pair of resilient fuse clip arms of the bias element may extend through the respective slots of the pair of fuse clip arms. The pair of resilient fuse clip arms may each include a distal end, and each respective slot may be located proximate the distal end.
The resilient bias element may include a generally planar section, and upstanding resilient arms extending obliquely from the generally planar section. A portion of each fuse clip arms may have a concave curvature complementary to a shape of the terminal element of the fuse. The fuse clip assembly may further include an anchor portion, and the pair of fuse clip arms may extend upwardly from the anchor portion. A connection portion may extend from the anchor portion, and the connection portion may be spaced from the pair of fuse clip arms. The connection portion and the fuse clip arms may be integral with the anchor portion. The bias element may be separately provided from the anchor portion.
The fuse clip assembly may be combined with the fuse, and the terminal element comprises one of a ferrule, an end cap, a knife blade contact, and a terminal blade.
An embodiment of a fuse holder for an electrical fuse having at least one conductive terminal element has been disclosed. The fuse holder includes: a base fabricated from an electrically nonconductive material; and a fuse clip assembly mounted to the base and configured to establish an electrical connection to the conductive terminal element of the overcurrent protection fuse. The fuse clip assembly includes: a pair of resilient fuse clip arms adapted to engage and retain a the terminal element of the fuse; and a bias element coupled to the pair of resilient fuse clip arms, the bias element movable relative to the pair of resilient fuse clip arms to a first position configured to resist deformation of the pair of resilient fuse clip arms when subjected to a compressive force and to moveable relative to the pair of resilient fuse clip arms to a second position configured to support the pair of resilient fuse clip arms when subjected to an expansion force.
Optionally, the pair of resilient fuse clip arms may each include a respective slot, and a portion of the bias element may extend through each respective slot of the pair of resilient fuse clip arms. The bias element may include a pair of resilient arms, and each of the pair of resilient fuse clip arms of the bias element may extend through the respective slots of the pair of fuse clip arms. The pair of resilient fuse clip arms each has a distal end, and each respective slot may be located proximate the distal end.
The resilient bias element may include a generally planar section, and upstanding resilient arms extending obliquely from the generally planar section. A portion of each fuse clip arm may have a concave curvature complementary to a shape of the conductive terminal element of the fuse.
The fuse holder may further include an anchor portion, the pair of fuse clip arms extending upwardly from the anchor portion. A connection portion may extend from the anchor portion, and the connection portion may be spaced from the pair of fuse clip arms. The connection portion and the fuse clip arms may be integral with the anchor portion. The bias element may be separately provided from the anchor portion.
The fuse holder may be combined with the fuse, and the terminal element may include one of a ferrule, an end cap, a knife blade contact, and a terminal blade.
An embodiment of a fuse holder for an electrical fuse having first and second conductive terminal elements and a fuse element therebetween has been disclosed. The fuse holder includes: a base fabricated from an electrically nonconductive material, and a first fuse clip assembly and a second fuse clip assembly mounted to the base in spaced apart relation to one another. Each of the pair of fuse clip assemblies are configured to establish an electrical connection to a respective one of the first and second terminal elements of the electrical fuse, and at least one of the first and second fuse clip assemblies includes: a pair of resilient fuse clip arms each adapted to engage and retain one of the first and second conductive terminal elements of the electrical fuse, and each of the pair of resilient fuse clip arms including a slot having a first width; and a bias element coupled to the pair of resilient fuse clip arms, the bias element including a pair of resilient arms having a thickness less than the first width, wherein the resilient arms of the bias element respectively pass through the slots in each pair of resilient fuse clip arms and a relative degree of freedom of movement of the resilient arms of the bias element relative to the fuse clip arms is provided in each respective slot, whereby the resilient fuse clip arms are movable to a first position to support the fuse clip arms when subjected to a compressive force and whereby the resilient fuse clip arms are movable to a second position to support the pair of resilient fuse clip arms when subjected to an expansion force.
Optionally, each of the pair of resilient fuse clip arms comprises a curved section, the curved section complementary to a curvature of the terminal element of the fuse.
The fuse holder may be combined with the fuse, and the terminal element may include one of a ferrule, an end cap, a knife blade contact, and a terminal blade.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Number | Name | Date | Kind |
---|---|---|---|
1122754 | Black | Dec 1914 | A |
1864283 | Steinmayer | Jun 1932 | A |
1940942 | Dohrwardt | Dec 1933 | A |
1955251 | Ohlson | Apr 1934 | A |
1983281 | Fries et al. | Dec 1934 | A |
2011391 | Bennett | Aug 1935 | A |
2041613 | Lincks | May 1936 | A |
2292320 | Hammerly | Aug 1942 | A |
2325697 | Millermaster et al. | Aug 1943 | A |
2388883 | Taylor | Nov 1945 | A |
2659063 | Webb et al. | Nov 1953 | A |
2665415 | Kojis | Jan 1954 | A |
2783331 | Sundt | Feb 1957 | A |
2889533 | Nielsen | Jun 1959 | A |
2942228 | Swick | Jun 1960 | A |
2943295 | Stewart | Jun 1960 | A |
3076953 | Sloop | Feb 1963 | A |
3198913 | Stanback | Aug 1965 | A |
3927929 | Puetz | Dec 1975 | A |
3960435 | Bailey et al. | Jun 1976 | A |
3984801 | Mrenna et al. | Oct 1976 | A |
4017816 | Latimer, Jr. | Apr 1977 | A |
4097114 | Motten, Jr. | Jun 1978 | A |
4108531 | Reynolds | Aug 1978 | A |
4128291 | Peterson, Jr. | Dec 1978 | A |
4178063 | Reynolds | Dec 1979 | A |
4257662 | Motten, Jr. | Mar 1981 | A |
4278316 | White | Jul 1981 | A |
4391485 | Urani | Jul 1983 | A |
4472018 | Urani | Sep 1984 | A |
4547036 | Keglewitsch et al. | Oct 1985 | A |
4775338 | Norden | Oct 1988 | A |
4932877 | Zinn | Jun 1990 | A |
4971582 | Keglewitsch et al. | Nov 1990 | A |
5295850 | Jeffcoat et al. | Mar 1994 | A |
7025634 | Swantner et al. | Apr 2006 | B1 |
7416455 | Salo et al. | Aug 2008 | B2 |
7595715 | Pavlovic et al. | Sep 2009 | B2 |
7766706 | Kawamura et al. | Aug 2010 | B2 |
7892050 | Pavlovic et al. | Feb 2011 | B2 |
8026786 | Darr et al. | Sep 2011 | B2 |
8419486 | Tyler | Apr 2013 | B2 |
8449338 | Gong et al. | May 2013 | B2 |
8460009 | Topolewski et al. | Jun 2013 | B1 |
8475220 | Glick et al. | Jul 2013 | B2 |
20130023150 | von zur Muehlen | Jan 2013 | A1 |
Number | Date | Country | |
---|---|---|---|
20140087600 A1 | Mar 2014 | US |