Patent Description:
The present disclosure relates to a fastener for coupling and electrically connecting electrical conductors, and more particularly to a shearable bolt positioned within a connector block for maintaining electrical contact with at least one electrical conductor. <CIT> describes a screw for electric connectors. <CIT> describes a terminal electrical connector for a conductor. <CIT> describes a bolt with a sherable head. <CIT> describes a torque limiting set screw.

In accordance with a first aspect of the present invention, a fastener for connecting an electrical conductor to a connector body is provided having the features of claim <NUM>.

Optional, preferred features are defined in the dependent claims <NUM> to <NUM>.

In accordance with a second aspect of the present invention, a method of connecting an electrical conductor to a connector body is provided having the features of claim <NUM>.

Optional preferred features are defined in claims <NUM> to <NUM>.

Other aspects will become apparent by consideration of the detailed description and accompanying drawings.

Before any embodiments are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Use of "including" and "comprising" and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of "consisting of" and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof.

<FIG> illustrate a connector including a connector body or block <NUM> and a fastener <NUM> for connecting an electrical conductor <NUM> (<FIG>) to the connector block <NUM> (<FIG> and <FIG>). The fastener <NUM> includes a first portion <NUM> and a second portion <NUM> positioned within the first portion <NUM>. The fastener <NUM> is configured to be inserted at least partially through an outer surface <NUM> of the connector block <NUM> to engage the electrical conductor <NUM> (<FIG>) positioned within the connector block <NUM>. More specifically, the first portion <NUM> is coupled to the connector block <NUM> and the second portion <NUM> is telescopically coupled to the first portion <NUM> for selective movement of the second portion <NUM> relative to the first portion <NUM>. In the illustrated embodiment, the connector block <NUM> includes a first bore <NUM> and a second bore <NUM>, and an inner wall <NUM> partitions the first bore <NUM> from the second bore <NUM>. Among other things, the inner wall <NUM> provides a mechanical stop for electrical conductors 6a, 6b (<FIG>) inserted into the first bore <NUM> and the second bore <NUM> to insure proper positioning of the conductors 6a, 6b and also to prevent leakage of fluid (e.g. oil) when connecting fluid impregnated conductors.

With reference to <FIG>, in the illustrated embodiment the first portion <NUM> includes a cylindrical body <NUM> having a first or upper end <NUM> and a second or lower end <NUM> opposite the upper end <NUM>. The cylindrical body <NUM> is adapted to engage openings <NUM> positioned on the outer surface <NUM> of the connector block <NUM> (<FIG>). The first portion <NUM> further includes an inner surface <NUM> and an outer surface <NUM>. Each of the inner surface <NUM> and the outer surface <NUM> extends between the upper end <NUM> and the lower end <NUM>.

As shown in <FIG> and <FIG>, the outer surface <NUM> includes a threaded section <NUM> and a non-threaded section <NUM>. The non-threaded section <NUM> is positioned adjacent the upper end <NUM>, while the threaded section <NUM> is positioned adjacent the lower end <NUM>. In the illustrated embodiment, the threaded section <NUM> of the outer surface <NUM> threadably engages threads <NUM> of the openings <NUM> of the connector block <NUM>. Threading the first portion <NUM> into one of the openings <NUM> inserts the first portion <NUM> into the outer surface <NUM> of the connector block <NUM>.

With reference to <FIG>, once the non-threaded section <NUM> engages the threads <NUM> of the opening <NUM>, the first portion <NUM> will stop inserting into the opening <NUM>. In the illustrated embodiment, the non-threaded section has a length that is configured to position the upper end <NUM> of the first portion <NUM> flush with the outer surface <NUM> of the connector block <NUM>. In other words, the first portion <NUM> can be threaded into one of the openings <NUM> to progressively insert the first portion <NUM> into the connector block <NUM> until the non-threaded section <NUM> is reached. The non-threaded section <NUM> is configured to inhibit rotation of the first portion <NUM> relative to the connector block <NUM> when the non-threaded portion <NUM> is adjacent (i.e., flush with) the outer surface <NUM> of the connector block <NUM>.

With reference to <FIG>, <FIG>, and <FIG>, the second portion <NUM> includes a head <NUM>, a base <NUM>, and a shearable section <NUM> positioned between the head <NUM> and the base <NUM>. The illustrated shearable section <NUM> extends from a lower end of the head <NUM> to a first or upper end <NUM> of the base <NUM>. Furthermore, the shearable section <NUM> includes an end <NUM> adjacent the upper end <NUM> of the base <NUM>. The illustrated shearable section <NUM> tapers from the head <NUM> to the end <NUM>. The head <NUM> is configured to be rotated by a drive tool (not shown) for inserting the fastener <NUM> into one of the openings <NUM> of the connector block <NUM>.

With reference to <FIG> and <FIG>, the illustrated head <NUM> includes a hex shape and an inner surface <NUM> defining a socket <NUM>. In other embodiments, the head <NUM> may include either the hex shape or the socket. The head <NUM> is configured to be rotated by the drive tool for inserting the first portion <NUM> and the second portion <NUM> into one of the openings <NUM>. The drive tool can be a hex key (e.g., Allen wrench) that is configured to engage the hex shape of the fastener <NUM>, and/or a socket wrench that is configured to engage the socket <NUM>.

The socket <NUM> extends from an upper surface <NUM> of the head <NUM> through an upper surface <NUM> at the first end <NUM> of the base <NUM>. The socket <NUM> is configured to facilitate removal of the base <NUM> from one of the openings <NUM> of the connector block <NUM> after the head <NUM> has been separated from the base <NUM>. In other words, the upper surface <NUM> of the base <NUM> includes the socket <NUM> for removal of the fastener <NUM> by the drive tool after the head <NUM> has sheared from the base <NUM>.

As shown in <FIG>, the shearable section <NUM> includes a fixed break off point <NUM> positioned at the end <NUM> of the shearable section <NUM> adjacent the base <NUM>. The head <NUM> is configured to separate from the base <NUM> at the fixed break off point <NUM>. Specifically, the drive tool applies a torque to the fastener <NUM> until the applied torque reaches a predetermined torque limit of the fixed break off point <NUM>. Subsequently, the torque applied by the drive tool separates (i.e., shears) the head <NUM> from the base <NUM> at the break off point <NUM> (<FIG>). In some embodiments, the socket <NUM> may include a blocking member (not shown) positioned within the head <NUM> (i.e., in the socket <NUM> between the upper surface <NUM> of the head <NUM> and the upper surface <NUM> of the base <NUM>). The blocking member may be a rubber insert, a projection extending from the inner surface <NUM> of the socket <NUM>, or another blocking feature. The blocking member is configured to inhibit insertion of the drive tool (e.g., Allen wrench) completely within the socket <NUM> such that the torque is applied to the head <NUM> of the fastener <NUM> and not to the base <NUM>. As such, the blocking member may ensure that the fastener <NUM> shears at the fixed break off point <NUM> when the predetermined torque limit is reached.

With reference to <FIG>, the base <NUM> includes an outer surface <NUM> extending from the first end <NUM> to the second end <NUM>. The outer surface <NUM> includes threads for threadably engaging threads on the inner surface <NUM> of the first portion <NUM> (<FIG>). In some embodiments, the inner surface <NUM> of the first portion <NUM> includes threads extending between the upper end <NUM> and the lower end <NUM>; in other embodiments, only a portion of the inner surface <NUM> may include threads. As such, the second portion <NUM> is configured to move relative to the first portion <NUM>. Furthermore, the second end <NUM> of the base <NUM> is adapted to engage the electrical conductor <NUM> (<FIG>). In other words, the base <NUM> can be threaded into the first portion <NUM> to progressively insert the second end <NUM> into the connector block <NUM> until the second end <NUM> contacts an outer surface of the electrical conductor <NUM> (<FIG>). More specifically, rotation of the second portion <NUM> relative to the first portion <NUM> progressively inserts the second portion <NUM> through the first portion <NUM>. As such, the fastener <NUM> can be adjusted to engage and provide electrical contact with electrical conductors of different sizes (i.e., different outer diameters, width, shape, circumference, etc.).

With reference to <FIG> and <FIG>, the first end <NUM> of the base <NUM> further includes a flange <NUM>. The flange <NUM> engages the upper end <NUM> of the first portion <NUM> for rotating the first portion <NUM> and the second portion <NUM> together. The first and second portions <NUM>, <NUM> are co-rotatable until the non-threaded section <NUM> of the first portion <NUM> reaches the threads <NUM> of one of the openings <NUM> (i.e., when the upper end <NUM> of the first portion <NUM> is flush with the outer surface <NUM> of the connector block <NUM>), thereby inhibiting rotation of the first portion <NUM> (<FIG>). Application of additional torque to the fastener <NUM> causes the flange <NUM> to shear or break off or separate from the base <NUM> (<FIG>). Subsequently, the second portion <NUM> can rotate relative to the first portion <NUM>.

As shown in <FIG>, <FIG>, and <FIG>, in operation, the fastener <NUM> is positioned within one of the openings <NUM> of the connector block <NUM>. Initially, the flange <NUM> of the base <NUM> couples the first and second portions <NUM>, <NUM> together for co-rotation at least in an insertion direction. The drive tool (not shown) applies a torque to the head <NUM> for insertion of the fastener <NUM> into the connector block <NUM> due to the engagement of the threads of the outer surface <NUM> of the first portion <NUM> and the threads <NUM> of one of the openings <NUM>. The applied torque rotates the fastener <NUM> to progressively insert the first portion <NUM> into the connector block <NUM> until the non-threaded section <NUM> is reached, thereby positioning the upper end <NUM> of the first portion <NUM> substantially flush with the outer surface <NUM> of the connector block <NUM>.

As a user continues to apply torque, the flange <NUM> breaks off of the base <NUM> and the second portion <NUM> begins to rotate relative to the first portion <NUM>. The base <NUM> of the second portion <NUM> extends from the first portion <NUM> towards the electrical conductor <NUM> (<FIG>) by rotation of the base <NUM> relative to the inner surface <NUM> of the first portion <NUM>. The predetermined torque limit is reached when the second end <NUM> of the base <NUM> engages the electrical conductor <NUM>. As such, the fastener <NUM> is configured to electrically connect the connector block <NUM> to the electrical conductor <NUM> using the first portion <NUM> and the base <NUM> of the second portion <NUM>. Upon application of additional torque, the head <NUM> shears from the base <NUM> at a predetermined fault feature (e.g., the shearable section <NUM>). In the illustrated embodiment, the shearable section <NUM> is recessed relative to an outer surface <NUM> of the connector block <NUM>, thereby avoiding the need to file down any sharp protrusions or wrap a material around the connector block <NUM>. In addition, the shearing of the head <NUM> provides a positive indication that the fastener <NUM> has been correctly installed and is sufficiently tightened. The base <NUM> includes the socket <NUM> for facilitating ease of removal of the fastener <NUM> from the connector block <NUM> once the fastener <NUM> has been installed (i.e., once the head <NUM> shears from the base <NUM>).

As shown in <FIG>, the fastener <NUM> is adaptable to engage electrical conductors 6a, 6b having different sizes. Specifically, the first portion <NUM> moves relative to the connector block <NUM> and the second portion <NUM> selectively moves relative to the first portion <NUM> for accommodating a range of sizes of the electrical conductors 6a, 6b. For example, a first electrical conductor 6a has a relatively large size compared to a second electrical conductor 6b, and the second end <NUM> of the base <NUM> engages the first electrical conductor 6a before the flange <NUM> breaks off of the base <NUM>. By comparison, the second electrical conductor 6b has a relatively small size such that the second end <NUM> of the base <NUM> engages the electrical conductor 6b after the flange <NUM> separates from the base <NUM>, and after the second portion <NUM> extends relative to the first portion <NUM>. As such, the fastener <NUM> can engage and maintain electrical contact with electrical conductors having different sizes. The fastener <NUM> provides electrical communication between the electrical conductors 6a, 6b and, at least in some cases, the connector block <NUM>. In other embodiments, an electrical conductor may have an intermediate size, and the second end <NUM> of the base <NUM> engages the electrical conductor after the flange <NUM> separates from the base <NUM>, but before the second portion <NUM> extends relative to the first portion <NUM>.

In some embodiments, an inner surface of the connector block <NUM> may have a knurled inner bore to break through oxide layers on the electrical conductors <NUM> and grip the conductors. In some embodiments, an oxide inhibitor may be used to abrade and penetrate the conductor oxides.

<FIG> shows a fastener according to another embodiment. A shearable section <NUM>' may include a shear pin (not shown) for co-rotation of the first portion <NUM>' and the second portion <NUM>'. Specifically, the first portion <NUM>' may include an aperture <NUM> positioned near the upper end <NUM>', and the base <NUM>' may include a corresponding aperture <NUM> near the upper end <NUM>'. The shear pin can extend through the apertures <NUM>, <NUM> to couple the first portion <NUM>' and the second portion <NUM>' together for co-rotation. Furthermore, the shear pin will break or shear upon application of a predetermined torque after a non-threaded section <NUM>' of the first portion <NUM>' engages the threads <NUM> of the opening <NUM>. After the shear pin breaks, the second portion <NUM>' can rotate relative to the first portion <NUM>'.

<FIG> illustrate a fastener <NUM> according to yet another embodiment. Features of fastener <NUM> that are similar to features of the fastener <NUM> are identified with similar reference numbers, plus <NUM>. At least some differences between the fastener <NUM> and the fastener <NUM> are described in detail.

As shown in <FIG> and <FIG>, the second portion <NUM> has an outer hex-shaped profile but does not include a socket extending through the head <NUM> and shearable section <NUM>. Also, as shown in <FIG> and <FIG>, notches or slots <NUM> are positioned adjacent one end (e.g., an upper end <NUM>) of a cylindrical body <NUM> of the first portion <NUM>. The slots <NUM> are configured to engage a tool (e.g., a keyed wrench) to permit a user to rotate both the first portion <NUM> and the second portion <NUM> to remove the fastener <NUM> from an opening <NUM> of a connector block <NUM> (<FIG>). Also, as shown in <FIG>, a portion <NUM> of an inner surface <NUM> of the first portion <NUM> proximate a lower end <NUM> (e.g., an end proximate an inner portion of the connector block <NUM>) includes threads, while a portion <NUM> of the inner surface <NUM> between the threaded portion <NUM> and an upper end <NUM> is smooth.

Claim 1:
A fastener (<NUM>) for connecting an electrical conductor (<NUM>) to a connector body (<NUM>), the fastener (<NUM>) comprising:
a first portion (<NUM>) adapted to engage an opening (<NUM>) of the connector body (<NUM>), the first portion (<NUM>) further including an outer surface (<NUM>) having a threaded section (<NUM>) and a non-threaded section (<NUM>), the non-threaded section (<NUM>) providing a stop to prevent over insertion of the first portion (<NUM>) into the opening (<NUM>) beyond a predetermined point;
a second portion (<NUM>) engaging the first portion (<NUM>), the second portion (<NUM>) including,
a head (<NUM>) including an inner surface (<NUM>) defining a socket (<NUM>); wherein the fastener (<NUM>) is configured to be rotated by a drive tool engaging the socket (<NUM>);
a base (<NUM>) coupled to the first portion (<NUM>), the base (<NUM>) including an end (<NUM>) adapted to engage the electrical conductor (<NUM>); and
a shearable section (<NUM>) positioned between the head (<NUM>) and the base (<NUM>);
wherein the socket (<NUM>) extends from an end surface (<NUM>) of the head (<NUM>), through the shearable section (<NUM>), and partially through the base (<NUM>) to facilitate removal of the base (<NUM>) from the connector body (<NUM>) after the head (<NUM>) has separated from the base (<NUM>);
wherein the base (<NUM>) is threadable into the first portion (<NUM>) to progressively insert the end into the connector body (<NUM>) until the end (<NUM>) contacts an outer surface of the electrical conductor (<NUM>);
wherein at least a portion of an inner surface (<NUM>) of the first portion (<NUM>) includes threads, and wherein an outer surface (<NUM>) of the base (<NUM>) includes threads for threadably engaging the threads on the inner surface (<NUM>) of the first portion (<NUM>);
characterized by
the fastener further comprising a blocking member positioned in the socket (<NUM>) between the end surface (<NUM>) of the head (<NUM>) and an upper surface (<NUM>) of the base (<NUM>) and configured to inhibit insertion of the drive tool completely within the socket (<NUM>) while the head (<NUM>) and base (<NUM>) are connected such that a torque is applied to the head (<NUM>) of the fastener (<NUM>) and not to the base (<NUM>).