Patent Description:
In conventional linear motor systems, a moving element is controlled to move along a track by electromotive force. In a moving magnet linear motor, the moving element typically includes a magnet that holds the moving element to the track. In order to allow movement the moving element generally has bearings which run along the track and is supported by guide rails or the like on the track. The guide rails may engage with the bearings or with the moving element itself. The bearings include plain bearings, ball bearings, needle bearings, roller bearings and the like. In conventional systems, it can be difficult to remove the moving elements from the track either because of the magnetic attraction or because of bearing engagement with the track or guide rails.

In conventional systems, bearings may have specific parallelism tolerances. If the conventional bearings do not meet these tolerances the bearings may be prone to binding during movement.

Conventional bearings are typically not able to move well on curvilinear profiles. While some bearing configurations exist that can move along curved profiles, they are generally costly, difficult to manufacture, and have flexibility constraints with regard to the curvilinear profiles.

Conventional bearings are often preloaded with preloading hardware and have preloading adjustments to ensure the bearings stay in positive contact with the guide rails.

Conventional bearings may have difficulty in achieving high precision, accurate, and repeatable movement along the direction of motion. Factors that may cause variability in precision include i) component manufacturing tolerances, ii) backlash or play, iii) how well the bearings are seated on the guide rail datum surfaces, and iv) the accuracy of the moving element position measuring system. Where backlash or play is the clearance caused by gaps between components or parts.

<FIG> show example conventional bearing systems. <FIG> shows a plain bearing system <NUM> with a moving element <NUM> and bearings <NUM> that are held onto guide rails <NUM> by the shape of the guide rail <NUM>. <FIG> shows a bearing system <NUM> with a moving element <NUM> having V wheel bearings <NUM> held onto guide rails <NUM>. <FIG> shows a bearing system <NUM> with a moving element <NUM> having recirculating ball bearings <NUM> held onto guide rails <NUM>. The recirculating ball bearings <NUM> are around the guide rails <NUM> and have ball bearings which roll on the guide rails <NUM>. If a moving element on a conventional system were to require inspection, maintenance, or replacement, the conventional guide rails would generally need to be disassembled or opened. The systems <NUM>, <NUM>, <NUM> may require mechanical disassembly of any of the moving element <NUM>, <NUM>, <NUM>, the bearings <NUM>, <NUM>, <NUM>, and the guide rails <NUM>, <NUM>, <NUM>, in order to remove the moving element <NUM>, <NUM>, <NUM> from the guide rails <NUM>, <NUM>, <NUM>. The conventional systems in <FIG> may require preloading or tight manufacturing tolerances on guide rails and bearings to achieve precise movement and positioning. The systems <NUM>, <NUM>, <NUM> may also be susceptible to binding if the rails are not parallel.

<CIT> discloses a linear motor conveyor system comprising a track comprising a first magnetic element for generating a magnetic field, and a first guide rail, the system further comprising a moving element comprising a second magnetic element and at least one first bearing, wherein the at least one first bearing engages with the first guide rail to support the moving element in both a direction of travel along the track (x-axis) and in a direction perpendicular to the direction of travel along the track (z-axis) that is also perpendicular to a magnetic force between the first magnetic element and the second magnetic element (y-axis) such that the moving element is substantially supported on the track by a magnetic force that is generated between the first magnetic element and the second magnetic element along the z-axis to the moving element on the track.

It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous systems.

It may be desirable for a bearing system to have a moving element with bearings that are easily removable from guide rails of a track. The bearing system would be intended to be viable for curvilinear profiles, tolerant to variations in the parallelism of the guide rails, not need preloading adjustments, and cost effective for high precision positioning.

A method for removing a moving element from a track of a conveyor system using a pry tool according to a first aspect of the invention is provided according to claim <NUM>. A set for removing a moving element from a track of a conveyor system using a pry-tool according to a second aspect of the invention is provided according to claim <NUM>. Further features according to embodiments of the invention are defined in the dependent claims.

Generally, the present disclosure provides a conveyor system with improved bearing system for supporting a moving element.

<FIG> illustrates a conveyor system <NUM> having a track section <NUM>. The track section <NUM> features one or more moving elements <NUM> (only one is illustrated) which are configured to ride or travel along a track <NUM>. Some of the principles of operation of a similar track section are described in more detail in <CIT>.

The conveyor system <NUM> can be composed of a plurality of track sections <NUM> which are mechanically self-contained and separable from one another so as to be modular in nature. In this embodiment, the track sections <NUM> are mounted on a support (not shown) so as to align and abut one another in order to form a longer track. In order to be modular, each track section <NUM> may house self-contained electronic circuitry for powering and controlling the track section <NUM>. The conveyor system <NUM> may include curved track sections <NUM>.

<FIG> illustrates a perspective view of the track section <NUM> with a cover plate removed to show a linear drive mechanism <NUM><NUM>. <FIG> shows the linear drive mechanism <NUM> and <FIG> shows the track section <NUM> with the linear drive mechanism <NUM><NUM> removed The linear drive mechanism <NUM><NUM> is formed as a stator armature <NUM><NUM> including a plurality of embedded coils <NUM> which are individually excited so that an electrically-induced magnetic flux produced by the stator armature <NUM><NUM> is located adjacent to a given moving element <NUM> to be controlled, in a direction normal thereto, without affecting adjacent moving elements <NUM>. The motive force for translating each moving element <NUM> arises from the magnetomotive (M MF) force produced by each moving element <NUM> and the stator armature <NUM><NUM>, i.e. , by the tendency of the corresponding magnetic fluxes provided by the stator armature <NUM> and moving element <NUM> to align. A controller (described below) enables separate and independent moving M MFs to be produced along the length of the track section <NUM> for each moving element <NUM> so that each moving element <NUM> can be individually controlled with a trajectory profile that is generally independent of any other moving element <NUM>. Structurally, the track section <NUM> may thus be broadly classified as a moving-magnet type linear brushless motor having multiple moving elements <NUM>.

Referring again to <FIG>, each moving element <NUM> includes an extension <NUM><NUM> provided with a machine readable medium <NUM> (not visible in <FIG>). In this embodiment, the machine readable medium is a magnetic strip but may alternatively be another appropriate medium such as an optically transmissive or reflective strip, or another type of feedback system or the like. The extension <NUM><NUM> is configured such that the machine readable medium <NUM> interacts with sensors <NUM> provided to the track <NUM>. The sensors <NUM> are configured to read the machine readable medium <NUM>, whether magnetically, optically, or otherwise as appropriate. The machine readable medium <NUM> and sensors <NUM> form a position sensing system. The position sensing system may be arranged such that the position sensing system is protected from traffic on the track section <NUM> and dust and other debris. For example, the machine readable medium <NUM> is located on the bottom side of the extension <NUM>.

The sensors <NUM> are located on the track section <NUM> and the machine readable medium <NUM> is located on the moving element <NUM>. In an alternative, the sensors <NUM> may be located on the moving element <NUM> and the machine readable medium <NUM> may be located on the track section <NUM>. The sensors <NUM> are configured to read a position of the moving element <NUM> on the track section <NUM> from the machine readable medium <NUM>.

<FIG> is a block diagram of an example control architecture <NUM> employed in the conveyor system <NUM>. Controller <NUM> controls the overall conveyor system <NUM> and the track <NUM> used in the conveyor system <NUM>. The controller <NUM> is configured to monitor moving element position and control the movement of moving elements <NUM> to go to desired destinations based on the moving element position. As such, the controller <NUM> can be used for process (i.e. manufacturing-line) control. The controller <NUM> may also provide a supervisory diagnostic role by monitoring the track sections <NUM> (e.g. , by engaging in a continuous polling or pushing process) in order to determine the current status of any track section <NUM> and whether any track section <NUM> has failed. It will be understood that, in some cases, the controller <NUM> may directly control each of the track sections <NUM>.

The controller <NUM> may also be connected to other devices, such as programmable logic controllers (PLCs) (not shown) via input/output (I/O) or network modules. The PLCs may provide manufacturing-line station-processing instructions to the track section <NUM>, such as directing the next destination for a moving element <NUM> along the track <NUM>, or providing station-specific motion instructions in respect of a given moving element <NUM>.

As illustrated, the controller <NUM> is connected to the stator armature <NUM> and coils <NUM><NUM> in the track sections <NUM> and controls the coils <NUM><NUM> in accordance with an independent trajectory or "move" command for each moving element <NUM> located therein.

The controller <NUM> is also connected to the sensors <NUM> situated in the track section <NUM>. The controller <NUM> is used to implement a closed-loop digital servo control system that controls movement of the moving element <NUM> by resolving the realtime position of each moving element <NUM> located in the track section <NUM>. When the machine readable medium <NUM> of a given moving element <NUM> moves over a given sensor <NUM>, moving element position feedback is transmitted to the controller <NUM>. The controller <NUM> decodes the moving element position feedback to determine the position of the moving element <NUM>.

Referring again to <FIG>, the conveyor system <NUM> includes the track <NUM> that produces a magnetic force for moving the moving element <NUM> along the track <NUM>. The magnetic force also captures the moving element <NUM> on the track <NUM>. The magnetic force is created by the interaction of the magnetic flux created by the embedded coils <NUM><NUM> of the track <NUM> and magnetic elements <NUM> of the moving element <NUM>. The magnetic force can be thought of as having a motive force component for directing movement of the moving element <NUM> along an X axis <NUM> (direction of travel) on the track <NUM>, a capturing force component to hold, on a Y axis <NUM> (laterally), the moving element <NUM> on the track <NUM>. In practice, the motive force and the capturing force is provided by the same magnetic flux elements <NUM>.

The track <NUM> includes a first guide rail <NUM> and a second guide rail <NUM> configured to support the moving element <NUM>. The first and second guide rails <NUM>, <NUM> are designed such that the moving element <NUM> may be removed from the track <NUM> when the magnetic force is overcome. The magnetic force is overcome, for example, where a user pries the moving element <NUM> away from the track <NUM>. In an alternative, the moving element <NUM> may be removed from the track <NUM> where the magnetic force is reversed, reduced, or removed.

The first guide rail <NUM> supports the moving element <NUM> vertically and horizontally. The first guide rail <NUM> may have a "V" shaped profile to support and guide the moving element <NUM> on the track <NUM>. The second guide rail <NUM> supports the moving element <NUM> horizontally. The second guide rail <NUM> may be a smooth surface with a flat profile.

<FIG> shows an example of a moving element <NUM> with magnetic elements <NUM>. The magnetic elements <NUM> provide a magnetic flux that corresponds to or interacts with the magnetic flux created by the coils <NUM><NUM> of the track <NUM>. In some embodiments, the magnetic elements <NUM> may be permanent magnets.

The moving element <NUM> has a first set of bearings <NUM> and a second set of bearings <NUM>. In this embodiment, the first set of bearings <NUM> is located above the second set of bearings <NUM>. The first and second set of bearings <NUM>, <NUM> may be wheel bearings that are rotatably attached to the moving element <NUM>.

The first set of bearings <NUM> rides on the first guide rail <NUM>. The first set of bearings <NUM> has an edge profile that corresponds to the profile of the first guide rail <NUM>. In an embodiment, the first set of bearings <NUM> has a "V" shaped profile that matches the opposite "V" shape profile of the first guide rail <NUM>. The first set of bearings <NUM> may alternately have a "U" shaped profile or another appropriately shaped profile intended to support the moving element <NUM> along a Z axis <NUM> (e.g. , vertically, shown in <FIG>). In certain cases, the moving element <NUM> has two bearings in the first set of bearings <NUM>.

The second set of bearings <NUM> rides on the second guide rail <NUM>. The second set of bearings <NUM> has an edge profile that corresponds to the profile of the second guide rail <NUM>. I n an embodiment, the second set of bearings <NUM> has a flat profile (e.g. , a flat wheel) that matches the flat profile of the second guide rail <NUM>. The second set of bearings <NUM> may roll a bit higher or lower on the second guide rail <NUM> to adapt to any non-parallelism with the first guide rail <NUM>. In some cases, the second set of bearings <NUM> includes a plurality of bearings.

Higher precision may be achieved over conventional conveyors by supporting the moving element <NUM> with magnetic force and the first set of bearings <NUM> to control the moving elements <NUM> along the Y axis <NUM> and the Z axis <NUM> including position and rotation. In certain cases, the first set of bearings <NUM> precisely contains the moving element <NUM> along the Y axis <NUM> and the Z axis <NUM> and precisely contains pitch rotation (about the Y axis <NUM>) and yaw rotation (about the Z axis <NUM>). The first set of bearings <NUM> provides precise movement and positioning along the X axis <NUM>.

The second set of bearings <NUM> contain rotation of the moving element <NUM> about the X axis <NUM>. The second set of bearings <NUM> may be positioned at a distance from the guide rail <NUM> to minimize variability due to rotation about the X axis <NUM> on the working surface <NUM>. The bearings <NUM> and the guide rail <NUM> may have tight tolerances on the dimensions that impact rotation about X axis <NUM> to allow precise positioning of the moving element <NUM> in rotation about the X axis <NUM>.

In the embodiment shown in <FIG>, the moving element <NUM> has two "V" shaped bearings <NUM> and two flat bearings <NUM>. The two flat bearings <NUM> and the two V- shaped bearings <NUM> (four bearings in total) may provide increased stability in rotation about the Z axis <NUM> or the X axis <NUM>. This may allow payloads mounted to the moving element <NUM> that have higher cantilever than a three bearing configuration. With four bearings <NUM>, <NUM>, the center of gravity of an added payload that is mounted to the moving element <NUM> may be shifted farther away from the track <NUM>.

<FIG> shows an alternate moving element <NUM> that has two "V" shaped bearings <NUM> and one flat bearing <NUM>. The one flat bearing <NUM> may provide for a single contact point with the second guide rail <NUM>. The one flat bearing <NUM> and two shaped bearings <NUM> (three bearings in total) may provide three point contact to ensure a consistent force of the bearings <NUM>, <NUM> on the guide rails <NUM>, <NUM>. The magnetic force of the permanent magnets <NUM> along the Y axis <NUM> is shared across all three bearings <NUM>, <NUM> consistently both while the moving element <NUM> is in motion and when stopped.

<FIG> illustrates the moving element <NUM> being removed from the track <NUM>, in accordance with an embodiment. The first and second set of bearings <NUM>, <NUM> are removable from the track <NUM> as the bearings <NUM>, <NUM> are not locked into the guide rails <NUM>, <NUM>. When the magnetic force generated between the magnets <NUM> and the stator armature <NUM><NUM> is overcome, the moving element <NUM> may be removed from the track <NUM>. For example, in the present embodiment, wherein the moving element uses permanent magnets, the moving element <NUM> may be pried off (e.g. , in a direction <NUM>) of the track <NUM> without any disassembly of bearings or guide rails or removal of the magnetic force. The moving element <NUM> may be removed from the track <NUM> by hand or by using a pry tool.

<FIG> illustrate the moving element <NUM> being removed from the track <NUM> using a pry tool, in accordance with an embodiment. In this embodiment, the moving element <NUM> is configured such that a pry tool <NUM> may be quickly attached and quickly detached from the moving element <NUM>. The moving element <NUM> includes one or more pins <NUM>. The pry tool <NUM> includes a corresponding set of grooves <NUM> and latches <NUM>. The pry tool <NUM> is brought towards the moving element <NUM> in the direction indicated by arrow <NUM>. The pins <NUM> are inserted into the grooves <NUM> and the latches <NUM> are closed to hold the pry tool <NUM> in place against the moving element <NUM>. In other embodiments, other mechanisms for attaching the pry tool <NUM> to the moving element <NUM> may be used. The pry tool <NUM> is designed to provide extended leverage to overcome the magnetic forces. Once attached, the extended leverage makes it easier for an operator to overcome the magnetic forces to remove the moving element <NUM> from the track <NUM> by moving the pry tool <NUM> in the direction indicated by arrow <NUM>. The pry tool <NUM> may optionally have offset handles to further increase leverage. The moving element <NUM> may be coupled to the track <NUM> by using the above procedure in reverse.

<FIG> are top perspective, bottom perspective, and side views of a moving element <NUM> having a working surface <NUM>, in accordance with an embodiment. The first set of bearings <NUM> may be mounted in a way to provide precise positioning of moving elements <NUM> and attachments to moving elements <NUM> as shown in <FIG>. The example working surface <NUM> may accommodate nests to contain parts that move through a manufacturing assembly line. Precise positioning of the working surface <NUM> may be achieved by having the first set of bearings <NUM> mounted close to the working surface <NUM> and on the same plane as the working surface <NUM>. Positioning of the bearings <NUM> and working surface <NUM> in this way is intended to minimize the number of stack up tolerances that contribute to precision error. Error may also be reduced by manufacturing components to tight tolerances on the dimensions that influence precision on the working surface <NUM>. The first set of bearings <NUM> may be mounted to the first guide rail <NUM> such that stack up errors are minimized.

The sensors <NUM> and machine readable medium <NUM> may be mounted close to the guide rail <NUM> and the first set of bearings <NUM> to provide precise position of the moving element <NUM>. The machine readable medium <NUM> may also be mounted on or near the same plane as the working surface <NUM> such that precise positioning is provided to the working surface <NUM>.

<FIG> illustrates a perspective view of the track section <NUM> with a cover plate removed, in accordance with an embodiment. In this embodiment, the sensors <NUM> are mounted directly on the first guide rail <NUM> engaged by the first set of bearings <NUM>. Having the sensors <NUM> mounted directly on the rail <NUM> that controls precision may minimize error due to thermal expansion and may reduce stack up tolerance errors over sensors that are mounted to a different structural element than the guide rail <NUM>.

<FIG> illustrates a conveyor system <NUM> having a curvilinear profile, in accordance with a further embodiment. In this particular example, the first set of bearings <NUM> and the second set of bearings <NUM> roll over guide rails <NUM>, <NUM>. The conveyor system <NUM> may not need tight tolerances with rail parallelism and there may not be binding of the moving element <NUM> and the track <NUM>. It is intended that binding may be avoided due to the second set of bearings <NUM> having room on the guide rail <NUM> such that they are free to roll slightly higher or lower on the guide rail <NUM>. Where the track section <NUM> is curvilinear, the sensors <NUM> are positioned along the curvilinear profile such that the machine readable medium <NUM> can be read by the sensors <NUM> and the readings are then translated from the curvilinear profile to a linear profile, using linear units such as microns, for the purposes of feedback control. Control of the moving element <NUM> then occurs in the linear profile/linear units.

<FIG> illustrate front and perspective views of a guide rail joint <NUM>, for example, of the mating of two first guide rails <NUM>. The guide rail joint <NUM> has a first guide rail <NUM> with an angled end <NUM> for mating to a corresponding angled end <NUM> of a guide rail <NUM> of an adjacent track section. The beveled ends <NUM>, <NUM> of the guide rails <NUM>, <NUM> may provide a smooth and effective transition from one track section to another. The moving element <NUM> is intended to roll smoothly from one track section <NUM> to the next due to a positive line of contact <NUM> of the bearings <NUM> across the guide rail joint <NUM>.

The guide rail joint <NUM> may be advantageous to a straight mating of adjacent track sections. The guide rail joint <NUM> may provide a stable riding surface across the joint and avoid causing the bearings <NUM> to dip into a gap reducing vibration and wear. Further, the guide rail joint <NUM> may be more tolerant to alignment variation than a straight joint as there is a gradual handoff region verses a straight joint. The line of contact <NUM> has stable contact on either guide rail <NUM>, <NUM> as there is an overlapping range within the guide rail joint <NUM> such that physical handoff can occur.

<FIG> illustrate perspective views of a moving element <NUM> with a magnetic shunt <NUM>, in accordance with an embodiment. In an embodiment, a magnetic shunt <NUM> may be provided to the moving element <NUM>. A magnetic shunt <NUM> may be a metal element that is placed in front of the moving element <NUM> which is used to complete the magnetic circuit of the magnetic elements <NUM>; for example, the magnetic shunt <NUM> may be a metal sheet. In some cases, the magnetic shunt <NUM> may be slid in front of the magnetic elements <NUM>, for example in the direction of arrow <NUM>, as magnetic sheer forces may be easier to overcome than forces perpendicular to the magnetic elements <NUM>. The magnetic shunt <NUM> may be placed on the moving element <NUM> manually or automatically. It is intended that placing a magnetic shunt <NUM> in front of the magnetic elements <NUM> may allow easier handling, greater reliability and increased safety when the moving element <NUM> is removed from the track <NUM> or when the moving element <NUM> moves to a part of the conveyor system <NUM> that does not use magnetic forces in the same way. In certain cases, the magnetic shunt <NUM> may allow the moving element to avoid unintentionally interacting with metallic or magnetic elements when the moving element is no longer coupled to the track <NUM>. In an example, there may be a shunt station in the conveyor system <NUM> that automatically places a magnetic shunt <NUM> on a moving element <NUM> when the moving element <NUM> arrives at the shunt station. With a magnetic shunt <NUM> in place, the moving element <NUM> may be removed from the track <NUM> or move onto another section of the conveyor system <NUM>, for example, a conventional belt conveyor.

The conveyor system <NUM> may not require added preload hardware or preload adjustments to keep the first set of bearings <NUM> in contact with the first guide rail <NUM> or the second set of bearings <NUM> in contact with the guide rail <NUM> as a preload is achieved by the magnetic force generated between the magnetic elements <NUM> and the stator armature <NUM>.

The conveyor system <NUM> is intended to achieve cost effective high precision positioning. The first set of bearings <NUM> control precision on the X axis <NUM>, the Y axis <NUM>, the Z axis <NUM>, and in rotation about the Y axis <NUM> and Z axis <NUM>. The guide rails <NUM> and the second set of bearings <NUM> control rotation about the X axis <NUM> with less sensitivity to variation. The number of bearing contact points that have an influence on precision is minimized. The magnetic force of the magnetic elements <NUM> is used for both thrust along the track <NUM> and bearing capture to keep the bearings <NUM>, <NUM> biased to the guide rails <NUM>, <NUM>. The same magnetic elements <NUM> used to generate thrust along the X axis <NUM> of the track <NUM> also captures the bearings <NUM>, <NUM> on the guide rails <NUM>, <NUM> with the magnetic force along the Y axis <NUM>. Other than the magnetic force along the Y axis <NUM>, no other elements are needed to capture the bearings <NUM>, <NUM>. The magnetic force also assists with taking up backlash in the conveyor system <NUM>. Mechanical backlash may be present between the bearings <NUM>, <NUM> and the guide rails <NUM>, <NUM>, between the bearings <NUM>, <NUM> and a shaft supporting the bearings <NUM>, <NUM> on the moving element <NUM>. The conveyor system <NUM> may have fewer parts manufactured to tight tolerances than in conventional systems in order to achieve high precision movement and positioning of the moving element <NUM>.

While the conveyor system <NUM> is shown with the track <NUM> in an upright or vertical orientation, it will be understood that the conveyor system <NUM> may be in any desired orientation while achieving at least one advantage described herein.

In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details may not be required. In other instances, well-known electrical structures and circuits are shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether the embodiments described herein are implemented as a software routine, hardware circuit, firmware, or a combination thereof.

Claim 1:
Method for removing a moving element (<NUM>) from a track (<NUM>) of a conveyor system (<NUM>) using a pry tool (<NUM>), the method comprising:
provide a conveyor system (<NUM>) comprising:
a track (<NUM>) comprising a first magnetic element (<NUM>); and
a moving element (<NUM>) comprising a second magnetic element (<NUM>) for interacting with the track (<NUM>) to provide a magnetic force that retains the moving element (<NUM>) on the track (<NUM>);
wherein absent the magnetic force, the moving element (<NUM>) is released from the track (<NUM>),
said moving element (<NUM>) including one or more pins (<NUM>);
provide a pry tool (<NUM>) including a corresponding set of grooves (<NUM>) and latches (<NUM>);
bring the pry tool (<NUM>) towards the moving element (<NUM>);
insert the pins (<NUM>) into the grooves (<NUM>) and close the latches (<NUM>) to hold the pry tool (<NUM>) in place against the moving element (<NUM>);
once attached, remove the moving element (<NUM>) from the track (<NUM>) by moving the pry tool (<NUM>).