Patent Description:
The invention relates generally a self-biasing belt scraper for cleaning a conveyor belt.

Conveyor belt systems typically include a cleaning system for removing debris and other materials from the outer surface of the conveyor belt. For example, scraper blades in contact with the belt surface may be used to remove material deposits from the belt surface. A typical scraper has a metallic or flexible plastic, e.g., polyurethane, body that is mounted on a support shaft that spans a conveyor belt and that usually includes a spring-based tensioner that biases the scraper into engagement with the conveyor belt to allow them to scrape leavings off of the belt and yet resiliently shift away from the belt when surface irregularities on the belt are encountered. For a positively-driven, low-tension conveyor belt such as the ThermoDrive® belt available from Intralox, L. , a separate position limiter system is usually required in the vicinity of the cleaning system for proper belt function, increasing the number of components required in the limited space surrounding the conveyor. <CIT> discloses a product removal method that includes providing a blade adjacent a conveyor belt along a path of the conveyor belt and operating the conveyor belt. <CIT> further discloses a self-biasing scraper comprising a base including an opening for receiving a shaft and having an upper surface for contacting the conveyor belt in a first location; and a tapering scraper tip extending from the base, the tip for contacting the conveyor belt in a second location. A glide or position limiter is also provided for exerting a force on the upper conveyor belt that is directed generally toward the upper conveyor drum. <CIT> discloses a cleaning assembly for a conveyor belt includes a first blade assembly, a second blade assembly, and a coupling mechanism supporting the first and second blade assemblies. The first blade assembly includes a first blade positionable into contact against a conveyor belt adjacent a turn portion of the belt. The second blade assembly includes a second blade positionable into contact against the belt downstream from the first blade. <CIT> discloses a conveyor employs a low-tension, direct drive conveyor belt, and a snap-on position limiter for ensuring proper engagement of the belt and a drive sprocket. The position limiter includes a body, a limiting surface and a snap clap opposite the limiting surface for snapping the position limiter to a mounting shaft. The limiting surface may comprise rotatable rollers mounted to the body, or a continuous arcuate surface. The position limiter may include a mounting arm for mounting a conveyor belt scraper at the front of the position limiter. In a first aspect of the present invention there is provided a self-biasing scraper for a conveyor belt as set forth in the claims.

These features and aspects of the invention, as well as its advantages, are described in more detail in the following description, appended claims, and accompanying drawings, in which:.

The present invention provides a self-biasing conveyor belt scraper for removing product and-or debris from a conveyor belt. The invention will be described relative to certain illustrative embodiments, though the invention is not limited to the embodiments described herein.

<FIG> show a discharge end of a conveyor belt <NUM> trained around a reversing element, shown as a sprocket <NUM>. The reversing element can be any suitable belt-guiding member, including a roller. The illustrative conveyor belt <NUM> comprises a positively-driven, low tension conveyor belt, such as the ThermoDrive® belt available from Intralox, L. , the Cleandrive positive drive belt available from Habasit AG, the Gates Mectrol PosiClean® positive drive belt available from Gates Mectrol, the Volta SuperDrive™ and other positive drive belts available from Volta Belting and other positively-driven, low tension conveyor belts known in the art. The conveyor belt is not limited to these belts, and may be implemented with any suitable positive-drive, low tension conveyor belt as well as any tensioned flat belt. The illustrative conveyor belt has a smooth outer surface substantially free of discontinuities and an inner surface with a plurality of drive elements, shown as teeth <NUM>, at a given belt pitch. The conveyor belt <NUM> conveys products along a carryway and returns along a returnway below the carryway. The illustrative sprocket <NUM> comprises a plurality of drive elements, shown as teeth <NUM>, for engaging drive elements <NUM> on the conveyor belt <NUM>. The sprocket <NUM> is mounted on a rotatable shaft <NUM>. The sprocket <NUM> may be a drive sprocket or an idle sprocket. Other suitable means for driving the belt may be used. As product approaches the end of the carryway, the conveyor belt <NUM> reverses direction, guided by the sprocket <NUM>.

A self-biasing scraper <NUM> is biased into contact with the conveyor belt <NUM>. The scraper <NUM> removes material from the outer surface of the conveyor belt as the belt moves over the sprocket or other belt guiding member. The self-biasing scraper <NUM> is mounted on a shaft <NUM> below the sprocket <NUM>. Referring to <FIG>, the self-biasing scraper <NUM> comprises a base <NUM> having a central opening <NUM> for receiving the shaft <NUM>. The illustrative base <NUM> is cylindrical or tubular, though the invention is not so limited. Alternatively, the base can be open and clamp onto the shaft <NUM> as in <FIG>. The base <NUM> forms a top surface <NUM> that contacts the conveyor belt outer surface at bottom location <NUM>, which is shown as <NUM>° from the top (<NUM>°) of the sprocket, though the invention is not limited to be positioned at this location. The top surface <NUM> is formed by a protrusion, bulge or other feature on the base <NUM> and can be concave, convex, or other complex geometries deemed appropriate.

A tapering scraper tip <NUM> extends from the base <NUM>. The tapering scraper tip forms a scraping edge <NUM> that contacts the outer surface of the conveyor belt <NUM> at a second location <NUM> to scrap away product and debris. The illustrative second location <NUM> is about <NUM>∘ from the top of the sprocket, though the invention is not so limited and the second point of contact can be any suitable location on the belt. The tip <NUM> includes a bar portion <NUM> extending at an angle from the base <NUM> towards the front of the sprocket <NUM>. The illustrative bar portion has a substantially consistent cross-section, though the invention is not so limited. The illustrative bar portion <NUM> extends perpendicular to the base <NUM>, but the angle of the bar portion relative to the base can be any suitable angle. The end <NUM> of the bar portion <NUM> bends slightly upwards and tapers to form the scraping edge <NUM>. The illustrative scraping edge is linear, though alternatively, the scraping edge can be nonlinear.

Referring back to <FIG>, the self-biasing scraper <NUM> is mounted on the shaft <NUM> so that the top surface <NUM> contacts the outer surface of the conveyor belt <NUM> at location <NUM>. As the conveyor belt <NUM> moves in direction <NUM>, the contact between the outer surface of the conveyor belt <NUM> and the top surface <NUM> causes the base <NUM> to rotate on the shaft <NUM> in direction <NUM>, which pushes the scraping edge <NUM> into contact with the outer surface of the conveyor belt at the second location <NUM>. As the scraper tip wears out, the scraper <NUM> self-adjusts to maintain contact with the conveyor belt outer surface at location <NUM>. The drag by the belt sliding over the base <NUM> provides uniform tension, ensuring that the scraper tip <NUM> conforms to the belt surface for better scraping performance.

The illustrative scraper tip <NUM> is integral with the base <NUM>, but the scraper tip or a portion thereof may be removable and-or replaceable. The scraper tip <NUM> may also or alternatively be formed of a different material than the base, or coated in a different material to optimize scraping.

The base portion <NUM> may function as a position limiter to ensure engagement of a driven tooth with a sprocket. Position limiters, such as described in <CIT>, may be used in low tension, positive drive belting systems to ensure proper engagement of the belt and drive sprocket by controlling the position of the belt during the drive tooth hand-off process. Preferably, the sprocket effectively drives only one tooth of the sprocket at a time, except for the duration in which a leading driven tooth disengages from the sprocket and hands off to the immediately trailing tooth as the trailing tooth becomes the leading driven tooth. The use of a position limiter helps control this handoff by ensuring proper engagement between the belt and corresponding sprocket. The base portion <NUM> is placed a select distance away from the sprocket <NUM> to force the driven tooth into the sprocket pocket and into engagement with the driver elements of the sprocket.

The position of the shaft <NUM> may be variable to ensure proper engagement and positioning of the self-biasing scraper <NUM>.

The self-biasing scraper <NUM> is not limited to a round base as shown. The base portion <NUM> may have any suitable size, shape, position or configuration to ensure engagement of the drive belt with the sprocket and proper contact between the scraper tip and belt when the belt is moving.

Referring to <FIG>, a self-biasing scraper <NUM> may include a counter weight <NUM> for increased tensioning of the scraper tip. The illustrative counter weight <NUM> comprises a central bar <NUM> and end discs <NUM>. The scraper <NUM> includes arms <NUM> extending from the base <NUM> substantially opposite the tapering scraper blade tip <NUM> for receiving the central bar <NUM>. As shown in <FIG>, the arms <NUM> include rounded tips <NUM> forming channels <NUM> for seating the counter weight central bar <NUM>. Arms <NUM> and the scraper blade tip <NUM> form a lever system pivoting about the shaft <NUM>, where the weight of the counter weight <NUM> is transmitted through the arms <NUM> and the tip <NUM> to the edge <NUM> to increase the pressure between the scraper edge <NUM> and the belt for improved scraping performance. The illustrative arms <NUM> take the shape of bars but the arms <NUM> can be any shape and dimensions to take the advantage of a lever system.

The self-biasing scraper in <FIG> also includes cut outs <NUM> in the scraper tip <NUM> to facilitate cleaning and -or to make the scraper tip <NUM> lighter.

In the illustrative embodiment, the scraper tip <NUM> and arms <NUM> are slightly less than <NUM>∘ apart.

As shown in <FIG>, a self-biasing scraper <NUM> with a tapering scraper tip <NUM> may include a single, solid arm <NUM> forming a continuous channel <NUM> for receiving a counter weight.

As shown in <FIG>, a self-biasing scraper <NUM> with a tapering scraper tip <NUM> may include an integral counter weight <NUM>. The counter weight <NUM> can be a solid plastic bar connected to the scraper base <NUM> by arms <NUM>. Alternatively, the counter weight <NUM> may have inserted rods made from materials such as stainless steel that are not visible from the outside. The illustrative counter weight <NUM> has the shape of a bar, but the counter weight <NUM> can be any shapes and may be made from the same or different materials as the base <NUM>. In the illustrative embodiment, the scraper tip <NUM> and the counter weight <NUM> are slightly less than <NUM>∘ apart.

Referring to <FIG>, in an embodiment of the invention, a self-biasing scraper <NUM> may be designed to receive snap-on position limiters. The self-biasing scraper <NUM> is mounted on a longitudinal mounting bar <NUM> within the base portion <NUM>. The longitudinal mounting bar <NUM> has a longitudinal channel <NUM> on an outer surface and notches <NUM>. A tapering scraper tip <NUM> extends from the base portion <NUM>. The scraper <NUM> further includes arms <NUM> for holding a counter weight <NUM>, which may alternatively be integrally formed with the rest of the scraper. The scraper tip <NUM> includes openings <NUM> exposing the bar <NUM>. A plurality of snap-on position limiters <NUM> may be mounted to the scraper <NUM>. Examples of snap-on position limiters are described in <CIT>, entitled "Snap-On Position Limiter for a Conveyor Belt". The invention is not limited to those described position limiters and the self-biasing scraper may be designed to accommodate any suitable auxiliary component in a conveyor. The illustrative position limiters <NUM> comprise a limiting surface <NUM> facing the conveyor belt for ensuring proper engagement of the sprocket and conveyor belt. The base of the position limiter forms a snap clamp for engaging the bar <NUM>. Each position limiter <NUM> fits into an opening <NUM> to snap onto the mounting bar <NUM>. The illustrative mounting bar <NUM> includes a longitudinal channel <NUM> and notches <NUM> for engaging corresponding features on the position limiter snap clamp. <FIG> is a bottom view of the self-biasing scraper <NUM>, with the position limiters <NUM> snapped into place. <FIG> is a side view of the self-biasing scraper <NUM>, with position limiters <NUM> snapped into place.

The scraper <NUM> can rotate freely about the shaft <NUM> without interfering with the limiter <NUM>, as shown in <FIG>.

<FIG> show another self-biasing scraper <NUM> including a tapering scraper tip <NUM> and an integral counter weight <NUM> extending from a base <NUM>. As shown in <FIG>, the base <NUM> can be an open segment of a tube that can receive a mounting bar via an opening <NUM> in the base <NUM>. The top of the base <NUM> contacts a moving conveyor belt at a first location to bias the tip <NUM> into contact with an outer surface of the conveyor belt at a second location.

Claim 1:
A self-biasing scraper (<NUM>) for a conveyor belt (<NUM>), comprising:
a base (<NUM>) including an opening for receiving a shaft (<NUM>) and having an upper surface for contacting the conveyor belt (<NUM>) in a first location (<NUM>); and
a tapering scraper tip (<NUM>) extending from the base (<NUM>), the tip (<NUM>) for contacting the conveyor belt (<NUM>) in a second location (<NUM>), the tapering scraper tip (<NUM>) including openings (<NUM>) exposing the shaft (<NUM>) each for receiving and mounting a position limiter (<NUM>) onto the shaft (<NUM>), characterised in that the shaft (<NUM>) includes a longitudinal channel (<NUM>) on an outer surface and notches (<NUM>) for mounting the position limiters (<NUM>), further comprising position limiters (<NUM>) each fitted into an opening (<NUM>) exposing the shaft and snapped onto the shaft (<NUM>).