ROLLER CONVEYOR GAP BLOCKER

Abstract

In one aspect, a space blocker having a body with an upper locking portion and body limb portions connected to the upper locking portion at longitudinally separate locations; the body limb portions having an initial, undeflected configuration with at least one of the limb portions having a first orientation with respect to the upper locking portion; the body limb portions having an operating configuration with the body in a space between rollers, wherein at least one of the limb portions has the first orientation with respect to the upper locking portion; the upper locking portion having upper contact portions and the limb portions having lower contact portions for making contact with the rollers;The body also has portions of outer surface intermediate to the upper and lower contact portions configured to be in clearance with the rollers.

Description

ROLLER CONVEYOR SPACE BLOCKER CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 081,410, filed on September 22, 2020, which is incorporated herein by reference in its entirety. FIELD OF INVENTION This description refers to roller conveyors and, more specifically, to gap blockers that block the spaces between rollers of roller conveyors. BACKGROUND OF THE INVENTION Roller conveyors are used to transfer objects from one location to another, such as packages in a distribution center and products in a manufacturing environment. Roller conveyors may use rollers that are rotatably supported in fixed positions. The rollers make contact with an object on the roller conveyor to transfer the object in a downstream direction along the conveyor. Roller conveyors have gaps between the rollers to allow them to rotate without making contact with each other. Occasionally, an item may fall through one of the gaps between the rollers and into an underlying area. Objects falling through the gaps between the rollers can damage an underlying structure, such as jamming a belt that drives the rollers and associated mechanisms. As another example, a portion of an object, such as a corner of a box, can become stuck in a gap between the rollers. These situations can adversely affect the operation of the roller conveyor and the surrounding environment. BRIEF DESCRIPTION OF THE INVENTION In one aspect of the present description, a gap blocker is provided for a roller conveyor having rollers and a gap between them. The gap blocker includes a body for positioning in the gap between the rollers, an upper blocking portion of the body to inhibit an object conveyed by the rollers from falling through the gap, and limb portions of the body connected to the upper blocking portion at longitudinally spaced locations such that the limb portions have a gap between them extending in the longitudinal direction. The limb portions of the body have an initial, undeflected configuration, with at least one limb portion having a first orientation relative to the upper locking portion. To facilitate the body's movement through space, the limb portions can be displaced relative to one another to decrease the distance across the space between them. For example, one limb portion can be moved toward the other, or both limb portions can be moved toward each other. The limb portions of the body have an operating configuration with the body in space. At least one limb portion has the first orientation relative to the upper locking portion, with the limb portions in the operating configuration, similar to when the limb portions are in the initial, undeflected configuration. The upper blocking portion has upper contact portions, and the end portions have lower contact portions to make contact with the rollers when the rollers rotate to carry the object downstream. In some applications, the lower contact portions are generally clear of the rollers and only make contact when necessary to limit vibration or other movement of the space blocker in space. The limited contact between the lower contact portions and the rollers reduces stress and wear on the space blocker and can provide a longer operating life. The body also has outer surface portions intermediate to the upper and lower contact portions along the rollers. These outer surface portions are configured to be in clearance from the rollers when the body is in the gap, and the end portions are in the operating configuration. In this way, the outer surface portions reduce the contact area between the body and the rollers, thus reducing the frictional resistance of the gap blocker to roller rotation. Reducing the frictional resistance of the gap blocker to roller rotation minimizes energy loss in the roller conveyor attributable to the gap blockers. The present description also provides a gap blocker that includes a body to be positioned in a gap between the rollers of a roller conveyor. The body has an upper blocking portion with upstream and downstream contact portions configured to make contact with the rollers above a narrower portion of the gap, and a resilient lower portion of the body that has upstream and downstream lower protrusions to make contact with the rollers. The upstream and downstream lower protrusions serve to form limited contact areas with the rollers, minimizing the frictional resistance of the resilient lower portion of the body to the rollers' rotation. In one approach, the upstream and downstream lower protrusions are configured to form a close, movable fit with the rollers. The resilient lower portion of the body has a deflected configuration where the resilient lower portion is narrower than the narrowest portion of the space, allowing it to advance through the narrowest portion and into an operational position below it. The resilient lower portion of the body also has a non-deflected configuration where the upstream and downstream lower protrusions are below the narrowest portion of the space.Because the resilient lower portion of the body is not deflected when the protrusions make contact with the rollers below the narrowest portion of the gap, the protrusions are positioned to resist vibration and other movement of the gap blocker while preventing tight clamping of the rollers by the gap blocker between the protrusions and the upstream and downstream contact portions of the upper blocking portion of the gap blocker body. The limited clamping of the rollers by the gap blocker facilitates low-friction contact between the gap blocker and the rollers. The resilient lower portion of the body has upstream and downstream clearance surface portions intermediate to the upper blocking portion of the body and the upstream and downstream lower protrusions along the body's height. The upstream and downstream surface portions of the resilient lower portion of the body are configured to be in clearance from the rollers when the body is in the operating position, further reducing the contact area of ​​the space blocker on the rollers and reducing the frictional resistance of the space blocker to roller rotation.The fact that the clearance surface portions are in clearance from the rollers means that these portions do not engage with the rollers when the space blocker is installed and during roller conveyor operation. This ensures that the clearance surface portions remain separate from adjacent rollers even when the rollers are running during roller conveyor operation. Again, by providing clearance surface portions that do not engage with adjacent rollers when installed or during roller conveyor operation, the space blocker is configured to minimize frictional engagement with the rollers.If a heavy object makes contact with the space blocker and causes one or both clearance surface portions to temporarily make contact with one or both rollers, the resilient lower portion returns the clearance surface portions to clearance with respect to the rollers once the object has been carried downstream of the space blocker. In another aspect of the present description, a roller conveyor is provided, comprising rollers, a space between the rollers, and a drive member extending around the rollers to transfer rotation from one roller to the other. The drive member, such as a butt joint, has upper and lower portions or races extending across the space and separated from each other by a distance. The roller conveyor also includes a gap blocker supported in the gap by the first and second rollers. The gap blocker has an upper blocking portion above a narrower portion of the gap, a lower portion below the narrower portion of the gap, and an intermediate portion that extends into the narrower portion of the gap. The gap blocker's height is less than the outside diameter of either roller and less than the distance between the upper and lower portions of the drive member. The gap blocker may be in clearance with the drive member either by having a portion of the gap blocker extend into an opening formed by the upper and lower portions of the drive member and the rollers, or by shifting laterally within the opening during roller conveyor operation.In this way, the space blocker protects the space against a transported object falling into it, while at the same time preventing interference with the driving member that rotates the rollers. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a roller conveyor system that includes rollers that rotate by means of a drive belt to transport an object in a downstream longitudinal direction and gap blockers that extend laterally into the spaces between the rollers; Figure 2 is a cross-sectional view taken through line 2-2 in Figure 1, showing one of the space blockers in a space between upstream and downstream rollers. The space blocker has a top surface that is cupped from the tops of the rollers to facilitate the movement of an object through the rollers without making contact with the space blocker. Figure 3 is an elevation view of the space blocker of Figure 2, showing an upper blocking portion and lower limb portions of the space blocker; Figure 4 is a perspective view of the space blocker in Figure 3, showing a thicker downstream limb portion and a thinner upstream limb portion of the space blocker; Figure 5 is an elevation view of the rollers and space blocker of Figure 2 when the space blocker is inserted into the space between the rollers; Figure 6 is a perspective view of another space blocker having a pair of upstream limb portions separated by an opening; Figure 7 is an elevation view of another gap blocker having identical lower limb portions and that can be installed in a gap between rollers with any limb portion making contact with the upstream roller associated with the gap; Figure 8 is a perspective view of the space blocker of Figure 7 showing the limb portions hanging from outer roller coupling portions of the space blocker; Figure 9 is an elevation view of another space blocker having limb portions with substantially straight portions that depend on an upper blocking portion of the space blocker; Figure 10 is an elevation view of another space blocker that has steep contact surfaces to make contact with the rollers; Figure 11 is an elevation view of another space blocker that is symmetrical about a central axis; Figure 12 is an elevation view of a portion of a roller conveyor that includes rollers, a drive member connecting the rollers, and a space blocker sized to fit in an opening formed by the rollers and the drive member; Figure 13 is an elevation view of a pair of rollers when a space blocker is inserted into a space between the rollers; Figure 14 is an elevation view of the rollers and space blocker of Figure 13 after the space blocker has been installed in the space. DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1, a conveyor system 10 is provided, which includes a roller conveyor 12 having rollers 14 that are driven by an underlying drive belt 16 to rotate in direction 18 and transfer an object in a downstream longitudinal direction 20. The drive belt 16 is looped by a motor 16A around head and tail pulleys (not shown in Figure 1). The drive belt 16 is driven in direction 22 to engage the lower portions of the rollers 14 to produce rotation in direction 18. The rollers 14 are rotatably mounted on rails 24 of a conveyor support structure 26 in fixed positions relative to the conveyor, so that the rollers 14 are stationary in the longitudinal direction 20 during operation of the roller conveyor 12. With respect to Figures 1 and 2, the rollers 14 have gaps 34 between adjacent pairs of rollers 14 upstream and downstream. The conveyor system 10 includes gap blockers or gap-blocking members 40 in the gaps 34 between adjacent rollers 14. The gap blockers 40 prevent objects from becoming stuck in the gap 34 or falling through it. The gap blockers 40 also limit debris, such as dust, dirt, and particles from the conveyed objects, from falling into the area below the rollers 14, such as onto the drive belt 16. Roller conveyors 10 typically have rollers 14 with the same outside diameter and roller spacing 14, so there is no variation in the gap 34 between one pair of rollers 14 compared to the gap 34 between another pair of rollers 14.This contrasts with conveyor belt systems that have gaps between the conveyor belts where the belt thickness can vary over time, or because different belts are used, causing the size of the gap between the conveyor belts to vary. Therefore, gap blockers 40 can have tighter tolerances than some transfer devices used to transfer objects between conveyor belts, since gap blockers 40 have a limited engagement with the rollers 14 instead of resiliently gripping the adjacent upstream and downstream rollers 14 to hold the gap blockers 40 in the gaps 34.The tighter tolerances of the space blockers 34 allow the space blockers 40 to have movable adjustments with the rollers 14, reducing the friction drag imparted to the rollers 14 by the space blockers 40 and improving the efficiency of the motor 16A driving the drive belt 16. As shown in Figure 2, the space blocker 40 has a body 42 with an upper blocking portion 44 and a lower portion 46 that includes an upstream lower member, such as the upstream limb portion 48, and a downstream lower member, such as the downstream limb portion 50. In one embodiment, the body 42 of the space blocker 40 has a one-piece unitary construction, where the space blocker 40 is a single monolithic member made entirely of the same material. For example, the space blocker 40 can be formed by extruding a material, such as a plastic material, to form a predetermined length of space blocker 40 extending between side sides 43A and 43B. In another embodiment, the space blocker can be a single part made of multiple materials.For example, body 42 may include a first material for a frame of body 42 and a second, low-friction material for the contact rollers. As an example, the first material may be UHMW polyethylene and the second material may be Teflon®. The multiple materials may be joined, for example, by an overmolding process in which the first material is injection molded in a first mold to form the frame of body 42. The frame of body 42 is then inserted into a second mold where the second material is injected and bonded to the frame. In yet another approach, body 42 may be formed from multiple parts that are mechanically connected, such as by press fits and / or by splice lugs and grooves. The space blocker 40 has a cross-section perpendicular to its length that is uniform along its length.Uniform phase through length is intended to mean that the cross section of the space blocker 40 perpendicular to the length is the same throughout the entire length of the space blocker 40. In other embodiments, the space blocker 40 can be manufactured by injection molding or roll forming, for example. During installation, an installer can cut each space blocker 40 to a length that substantially fills the entire side width of the associated space 34. In this regard, the default length of the space blocker 40 can be approximately the same as the length of the rollers 14. In another embodiment, a plurality of shorter space blockers 40 can be installed in a space 34 to fill the gap. One or more of the limb portions 48, 50 of the elongated space blocker 40 are resilient to allow resilient deformation for installing the space blocker 40 in space 34. The rollers 14 include elongated rollers 30, 32 with cylindrical outer surfaces 60, 62 that make contact with an object as they rotate to carry the object in the downstream direction 20. The space blocker 40 includes a top surface 52 that is recessed for a distance 54 from the top surface portions 56 of the rollers 30, 32. As shown, 54 is the vertical distance measured from a horizontal tangent line 55 to the top 56 of the rollers 30 downward to the recessed top surface 52 of the space blocker 40.The recessed upper surface 52 allows an object to travel through the gap 34 by making contact with the surfaces 60, 62 of the rollers 30, 32 without making contact with the upper surface 52 of the gap blocker 40. Furthermore, the gap blocker 40 makes contact with a portion of the transported object if that portion extends within the gap 34 sufficiently to cover the distance 54, thereby blocking or preventing the portion from extending further within the gap 34 and potentially becoming stuck between the rollers 30, 32. In some embodiments, the gap blocker 40 can be configured to fit higher within the gap 34, so that the gap blocker 40 is operable to assist in the transfer of objects between the rollers 30, 32. With respect to Figure 2, the upper locking portion 44 of the body 42 includes an upstream outboard portion 66 and a downstream outside roller coupling portion 68 that contacts the roller surfaces 60, 62 on their upper halves above the horizontal diameter lines 70, 92 of the rollers 30, 32. The upper locking portion 44 has a center portion 45 that extends between the joints of the upper locking portion 44 with the end portions 48, 50. The upstream outboard portion 66 extends generally continuously from the joint of the upper locking portion 44 with the end portions 48, and the downstream outside roller coupling portion 68 is at the joint of the upper locking portion 44 and the end portion 50.The upstream outboard portion 66 and the downstream outer roller coupling portion 68 can form line contacts with the roller surfaces 60, 62. Each line contact is a localized area of ​​mating between the contact surface and the roller that extends linearly in a lateral direction along the length of the roller. The end portions 48, 50 can be dimensioned so that they do not extend below a plane connecting the lower portions of the rollers 30, 32, and so that they cannot interfere with a belt driving the lower portions of the rollers 30, 32. The upstream outboard portion 66 makes contact with roller surface 60 at a surface portion 72 that has an acute angle 74 from the diameter line 70 of the upstream roller 30. The upstream extremity portion 48 has a free end portion that includes a contact portion 80 that makes contact with a surface portion 82 of roller surface 60 at an acute angle 84 below the diameter line 70 of roller 30. In one embodiment, angle 74 is on the 30-60 degree scale and angle 84 is on the 20-50 degree scale. Angle 74 may be larger than angle 84. With respect to Figure 2, the downstream outer roller coupling portion 68 makes contact with an arcuate surface portion 90 of the cylindrical roller surface 62 above the diameter line 92 of the downstream roller 32 and forms a line contact with the cylindrical roller surface 62 of the downstream roller 32. The downstream end portion 50 includes a free end portion which includes a contact portion 94 that makes contact with a surface portion 96 of the roller surface 62 below the equator 92. The contact portions 80, 94 of the upstream and downstream end portions ΙΛ / t / ZUZÓ / UOO IUO below 48, 50 can form line contacts with roller surfaces 60, 62. The roller surfaces 60, 62 can be made of a metallic material, such as stainless steel, and the body 42 of the space blocker 40 can be made of a polymer, such as ultra-high-molecular-weight polyethylene (UHMW) or another plastic, that has a low coefficient of friction with the roller surfaces 60, 62. Furthermore, the space blocker is configured to slide-engage the roller surfaces 60, 62 with in-line contacts that minimize the contact area between the space blocker 40 and the rollers 30, 32. In this way, the space blockers 40 prevent objects from becoming stuck in space 34 and prevent objects or debris from falling through space 34, while also minimizing the resistance of the space blockers 40 to the rotation of the rollers 14. With respect to Figures 2 and 3, the space blocker 40 has an initial configuration in which the contact portions 80, 94 of the upstream and downstream limb portions 48, 50 are separated by a maximum distance 100. The contact portions 80, 94 include projecting corner portions 81, 95 formed by foot portions extending inversely 152, 154 from the limb portions 48, 50. The maximum distance 100 is measured between the projecting corner portions 81, 95. The projecting corner portions 81, 95 have convex surfaces 81A, 95A that contact the convex outer surfaces of the rollers 30, 32. The convex surfaces 81A, 95A are where the limb portions 48, 50 contact the rollers 30, 32. 32.The convex surface 81A has a sliding contact engaged with roller 30, and the convex surface 95A has a clearance fit with roller 32, as a close movable fit. The remaining end portions 48, 50 are separated from rollers 30, 32 to reduce frictional resistance to the rotation of rollers 30, 32. The distance 100 is greater than a distance between the surface portions 82, 96 of the rollers 30, 32 so that, with the installation of the space blocker 40 in space 34, the limb portions 48, 50 are resiliently deflected in contact with the roller surfaces 60, 62 to keep the space blocker 40 in space 34. In one embodiment, the downstream limb portion 50 has a greater thickness 106 than a thickness 108 of the upstream limb portion 48 over at least a greater part of its length. This configuration allows the upstream limb portion 48 to be more easily diverted to push it towards the downstream limb portion 50 and decrease the distance between limb portions 48, 50 to fit limb portions 48, 50 within space 34, as described below with reference to Figure 5.The thinner upstream limb portion 48 can also be bent to compensate for slight movements of the upper locking portion 44 and to keep the upstream outboard portion 66 engaged with the upstream roller 30. In one embodiment, the upper locking portion 44 has a thickness 107 that is substantially similar, as in + / - 5%, to the thickness 106 of the downstream limb portion 50. The corresponding thicknesses 106, 107 of the upper locking portion 44 and the downstream limb portion 50 provide rigidity to the downstream limb portion 50 so that the limb portion 50 resists the frictional forces imparted on the space blocker 40 as described herein. The limb portions 48, 50 are advanced in space 34 in direction 110 (see Figure 2) sufficiently for the upstream outboard portion 66 and the downstream outer roller coupling portion 68 to engage the rollers. Once the projecting corner portions 81, 95 of limb portions 48, 50 advance beneath the equators of rollers 30, 32, the upstream limb portion 48 is resiliently displaced away from the downstream limb portion 50 and is deflected closely against the roller surface 60. In this way, the upstream limb portion 48 engages closely with the upstream roller 30.The offset coupling between the contact portion 80 of the upstream limb portion 48 and the upstream roller 30 forms an anchor point 114 for the space blocker 40, which is located on the lower half of the roller 30 at a circumferentially fixed location as the surface 60 rotates below its equator or horizontal diameter line 70. The anchor point 114 is positioned a predetermined distance below the diameter line 70, which, in turn, keeps the upstream outboard portion 66 coupled to the roller surface 60. This limits the lifting of the upstream outboard portion 66 away from the roller surface 60 and the associated vibration of the space blocker 40.The upstream limb portion 48 is configured to have a radial interference or overlap 112 with the outer roller surface 60 so that the upstream limb portion 48 is deflected by the outer roller surface 60 when the gap blocker 40 is in gap 34. The radial overlap 112 resiliently deflects limb portion 48 and provides a preload for limb portion 48, so that limb portion 48 resiliently maintains the upstream outboard portion 66 in tight engagement with the roller surface 60. The downstream end portion 50 is thicker than the upstream end portion 48 and rigidly resists deflection, so that the downstream end portion 50 remains undeflected with the space blocker 40 installed in space 34 even though the upstream end portion 48 is deflected. The downstream end portion 50 is configured to remain undeflected with the space blocker 40 installed in space 34 and during normal operation of the conveyor system 10, but there may be occasional or constant minimal deflection due to forces applied to the downstream end portion 50 by the rotating roller 32. Additionally, the downstream end portion 50 may deflect when a conveyed object makes contact with the space blocker 40.As shown in Figures 2 and 3, the downstream limb portion 50 has the same orientation with respect to the upper blocking portion 44 when the space blocker 40 is in space 34 and when the space blocker 40 is outside of space 34. The upstream limb portion 48 has a different orientation with respect to the upper blocking portion 44 when the space blocker 40 is in space 34 and when the space blocker 40 is outside of space 34. More specifically, the upstream limb portion 48 is deflected when the space blocker 40 is inside space 34 due to interference between the upstream limb portion 48 and the outer surface of roller 60. With regard to Figure 2, during conveyor operation, the contact between the upstream outboard portion 66 and the roller surface 60 generally pushes the upstream outboard portion 66 in the downstream direction 20 and presses the downstream outer roller coupling portion 68 against the roller surface 62. The sliding contact between the downstream outer roller coupling portion 68 and the roller surface 62 tends to lift the downstream outer roller coupling portion 68, which presses the contact portion 94 of the downstream end portion 50 against the roller surface 62.Due to its thicker construction, the downstream limb portion 50 is strong enough to resist deflection toward the upstream limb portion 48 caused by the cam forces generated by this lifting motion of the downstream outer roller coupling portion 68 in the vertical direction 120 and keeps the downstream outer roller coupling portion 68 and the contact portion 94 engaged with the roller surface 62. In addition, the contact portion 94 of the downstream limb portion 50 forms an anchor point 122 for the gap blocker 40 below the equator 92 of the roller 32. With reference to Figures 2 and 3, the upstream and downstream limb portions 48, 50 have upstream and downstream surfaces 180, 182 respectively, which are oriented toward and away from the respective roller surfaces 60, 62.Surfaces 180 and 182 can be extended over most of the length of limb portions 48 and 50, respectively, to reduce friction between space blocker 40 and roller surfaces 60, 62 and allow space blocker 40 to remain in position between rollers 30, 32. The roller conveyor 12 has roller bearings 130 that connect the rollers 30 to the rails 24 (see Figure 1). With reference to Figure 2, the conveyor system 10 may also include skirt walls 132 that extend along opposite sides of the rollers 14 to retain objects on the rollers 14. With reference to Figure 3, the upstream outboard portion 66 includes an edge 136 that may be sharper than the rounded edge 140 of the downstream outer roller coupling portion 68. The edge 136 may provide a low-profile transition from the roller surface 60 to limit the risk of the edge 136 becoming caught on an object transferred from roller 30 to roller 32. The upstream outboard portion 66 also includes a lower tapered surface 142 that may be flat, extending obliquely with respect to the upper surfaces 52, or concave to more closely match the curvature of the roller surface 60. The upstream outboard portion 66 projects outward from a transition portion 146 between the upstream outboard portion 66 and the limb portion 48.The transition portion 146 connects the upstream limb portion 48 to the blocking portion 44. With respect to Figure 3, during the installation of the space blocker 40, the upstream limb portion 48 can be pushed in direction 150 toward the downstream limb portion 50 to decrease the distance 100 between the contact portions 80, 94 of the upstream and downstream limb portions 48, 50 to allow the limb portions 48, 50 to advance into space 34. The upstream and downstream limb portions 48, 50 can include the inversely extending foot portions 152, 154, which generally extend back toward each other, and a central axis 160 of the space blocker 40. The foot portions 152, 154 include inclined surfaces 156, 158 that extend transversely to the central axis 160 of the space blocker 40.One or more of the inclined surfaces 156, 158 can be cam-coupled with the roller surfaces 60, 62 of the rollers 30, 32 to push together the end portions 48, 50 when the end portions 48, 50 are advanced into space 120. With respect to Figure 4, the upper surface 52 of the space blocker 44 includes a flat surface portion 162 and tapered surface portions 164, 166. The space blocker 40 includes opposite end portions 170, 172 having side sides 174, 176. The side sides 174, 176 may be flat or have other profiles. As illustrated, the space blocker 40 may be configured to extend along the adjacent rollers 30, 32 along most, or substantially all, of the length of the space 34 so that only one space blocker 40 is in the space 34. It is also contemplated that there may be two or more space blockers 40 positioned side by side in the space 34 to fill the side length of the space 34. ΙΛ / t / ZUZÓ / UOO IUO With regard to Figures 4 and 5, there is a space 184 between the upstream and downstream limb portions 48, 50 that can be made narrower by pushing the upstream limb portion 48 towards the downstream limb portion 50 during the installation of the space blocker 40 in space 34. To install space blocker 40 within space 34, space blocker 40 is first tilted (see figure 5) so that the center axis 160 (see figure 3) of space blocker 40 extends obliquely to an axis perpendicular to the downstream longitudinal direction 20. Space blocker 40 is tilted so that the downstream end portion 50, which is thicker, is closer to space 34 than the upstream end portion 48, which is thinner. The space blocker 40 is then advanced in direction 110 to advance the downstream limb portion 50 into space 34 and seat the downstream outer roller coupling portion 68 against the outer surface 62 of roller 32 as shown in Figure 5. Additionally, the foot portion 152 of the upstream limb portion 48 can rest on the outer surface 60 of roller 30. Direction 110 is generally orthogonal to the downstream transportation direction 20, so that with the horizontal transportation direction illustrated, direction 110 is generally vertical. Next, the installer pivots the upstream limb portion 48, generally in direction 190, toward the downstream limb portion 50 to decrease the size of the gap 184 between the upstream and downstream limb portions 48, 50. The installer then swings the gap blocker 40 in direction 192 while holding the upstream limb 48 in its deflected position near the downstream limb 50 so that the sloped surface 156 of the foot portion 152 slides along the roller surface 60 and the foot portion 152 advances along direction 110 further into the gap 34. The installer presses the locking portion 44 to push the gap blocker 40 further into the gap 34 until the contact portion 156 of the upstream limb portion 156 clicks below the horizontal diameter 70 roller 30.In some modalities, the downstream limb portion 50 is rigid enough to resist deflection and maintain the orientation shown in Figure 5 with respect to the upper locking portion 44 when the upstream limb 48 is deflected in the 190 direction and the upstream and downstream limb portions 48, 50 advance in the 110 direction within space 34. Due to the lateral length of the space blocker 40, an installer can first position a side portion 170, 172 in space 34 by pushing the portion of IL / t / ZUZÓ / UOO IUO upstream limb 48 towards downstream limb portion 50 as described above. Then the installer can position the other sideside portion 170, 172 in space 34 by continuing to push the upstream limb portion 48 towards the downstream limb portion 50 and pressing the other sideside portion 170, 172 into space 34. With regard to Figure 6, another space blocker 200 is provided that is similar in many respects to the space blocker 40 described above; therefore, only the differences will be described. The space blocker 200 includes a unitary body 202 having an upper blocking portion 204 and lower limb portions 206. The limb portions 206 include a downstream limb portion 208 and a pair of upstream limb portions 210, 212. The space blocker 200 can have two, three, four, or any number of separate upstream limb portions as desired for a particular application. The upstream extremity portions 210, 212 have lateral surfaces 214, 216 separated laterally by an opening 218. The opening 218 provides a reduced surface contact area against an upstream roller in the lower upstream portion of the space blocker 200.More specifically, the space blocker 200 has a pair of relatively small contact portions 220, 222 of the upstream end portions 210, 212 that engage against an upstream roller. The contact portions 220, 222 have convex surfaces that form line contacts with the convex outer surface of the upstream roller. This can reduce frictional contact between the space blocker 20 and the upstream roller. With regard to Figure 7, another space blocker 300 is provided that is similar in many respects to the space blockers described above; therefore, only the differences will be described. The space blocker 300 includes an upper locking portion 302, end portions 304 and 306, and upstream and downstream outer roller coupling portions 308 and 310 of the body 301. The space blocker 300 is symmetrical about a central axis 312. The symmetry of the space blocker 300 allows it to be installed in a space between rollers, with either the end portion 304 or the end portion 306 positioned against the upstream roller.The end portions 304, 306 are configured symmetrically and have similar thickness 314, 316 to be provided with similar flexibility so that any end portion 304, 306 can be deflected towards the other end portion 304, 306 in directions 230, 233 during the installation of the space blocker 300. With reference to Figure 8, the roller coupling portions 308, 310 each have a rounded edge 330 to form a line contact with the associated roller. IA / t / ¿U¿ó / UOO IUO The 300 space blocker may have a thickness 340 of the upper blocking portion 302 that is substantially equal to the thickness 314, 316 of the extremity portions 304, 306. The thicknesses 314, 316, 340 may be + / - 5% of each, as some examples. With regard to Figure 9, a space blocker 400 is provided that is similar in many respects to the space blockers described earlier; therefore, only the differences will be described. The space blocker 400 has a body 402 that includes an upper locking portion 404 to block a space 406 and a lower portion 408 to retain the space blocker 400 in the space 406. In one embodiment, the body 402 has a unitary, one-piece construction. The body 402 may be made of a plastic material, such as injection molded, extruded, or additively manufactured, as some examples. The upper locking portion 404 includes outboard portions 410, 412, and a center portion 414. Outboard portions 410, 412 each have tapered upper surfaces 416, edges 418, 419, and tapered lower surfaces 420, 421 that taper toward each other at outboard edges 418, 419.The tapered lower surfaces 420 of the outboard portions 410, 412 can make contact with cylindrical surfaces 422, 424 of the rollers 426, 428. In some embodiments, the edges 418, 419 form contacts with the surfaces 422, 424. The space blocker 400 has a central axis 430 and is symmetrical about the central axis 430. This allows the space blocker 400 to be positioned in a space 406 with any outboard portion 410, 412 oriented to make contact with the upstream roller 426 to receive and block the space 406 from falling an object traveling in the direction 440. The lower portion 408 of the body 402 includes limb portions 450, 452 with contact portions 454, 456 that make contact with roller surfaces 422, 424 below the diameter lines 460, 462 of rollers 426, 428. The limb portions 450, 452 each have outer surfaces 490, 492 that are separated by spaces 494, 496 from the surfaces 422, 424 of rollers 426, 428 to limit contact between space blocker 400 and rollers 426, 428.This separation between surfaces 490, 492 and the adjacent rollers 426, 428 is present once the space blocker 400 is installed between the rollers and, after installation, during the operation of the roller conveyor. Therefore, as the rollers 426, 428 rotate, the surfaces 490, 492 of the space blocker 400 remain separated from the adjacent rollers 426, 428 along their entire length to prevent any frictional coupling between them. The space blocker 400 is supported in space 406 by the outboard portions 410, 412 in sliding contact with the roller surfaces 422, 424, and by the weight of the space blocker 400, keeping the outboard portions 410, 412 in contact with the roller surfaces 422, 424. The contact portions 454, 456 of the limb portions 450, 452 are generally in clearance from the roller surfaces 422, 424, as having a close movable fit with the roller surfaces 422, 424. The contact portions 454, 456 of the limb portions 450, 452 may occasionally make contact with the roller surfaces 422, 424 to resist or minimize vibration of the space blocker 400.The contact portions 454, 456 of the limb portions 450, 452 are normally in clearance with the roller surfaces 422, 424 during the operation of rollers 426, 428, which limits the surface area of ​​the space blocker 400 that can resist the rotation of rollers 426, 428 and reduces the frictional resistance of the space blocker 400 to the rotation of rollers 426, 428. Furthermore, the limb portions 450, 452 are in a non-deflected configuration when the space blocker 400 is in space 406, such that the clamping of rollers 426, 428 between the outboard portions 410, 412 and the limb portions 450, 452 is prevented, further reducing the frictional resistance of the space blocker 400. space blocker 400 to the rotation of rollers 426, 428.In this way, the gap blocker 400 can block a transported object from falling through gap 406 while maintaining the operating efficiency of the roller conveyor. The upper locking portion 404 includes a top surface 466 that is recessed relative to the top surface portions 468, 470 of rollers 426, 428. This allows packages or other objects to be transferred in the downstream direction 440 from roller 426 to roller 428 without making contact with the space blocker 400. In other embodiments, the space blocker 400 is configured to position the upper locking portion 404 higher in space 406 so that objects are transferred from roller 426 to roller 428 via the top surface 466. Body 402 includes joints 474, 476 between the limb portions 450, 452 and the upper locking portion 404. The limb portions 450, 452 include substantially straight portions 480, 482 hanging from the joints 474, 476. The straight portions 480, 482 extend at an angle 484 with respect to the outboard portions 410, 412. The straight portions 480, 482 may have a thickness in the longitudinal direction that decreases as the limb portions 480, 482 extend downward from the upper locking portion 404, distributing the bend of the limb portions 480, 482 over the length of the straight portions 480, 482. In one embodiment, the Angle 484 is substantially perpendicular, that is, ninety degrees plus or minus five degrees.The orientation of the outboard portions 410, 412 and the straight portions 480, 482 of the limb portions 450, 452 create a branched shape of the upstream and downstream sides of body 402, as body 402 extends away from the central portion 414 of body 402. The extremity portions 450, 452 extend downward away from the upper locking portion 404 and include lower curved portions 500, 502 that curve below the horizontal diameter lines 460, 462 of the rollers 426, 428. The curved portions 500, 502 position the end portions 504, 506 of the extremity portions 450, 452 below the diameter lines 460, 462. The extreme portions 504, 506 include contact portions 454, 456. In one embodiment, the contact portions 454, 456 include convex surface portions 510, 512, each having a radius of curvature 514, 516 that may be similar or different. The end portions 504, 506 also include inclined surface portions 520, 522 that can be clamped against the roller surfaces 422, 424 as the limb portions 450, 452 advance downwards within the space 406 so that the engagement therewith pushes the limb portions 450, 452 towards each other so that the contact portions 454, 456 can advance past the narrowest portion of the space 406 defined between the diameter lines 460, 462 of the rollers 426, 428. The end portions 504, 506 may include foot portions 524, 526 having portions of the convex surface portion 512 and / or the inclined surface portion 522 thereon.With regard to Figure 10, a 600 space blocker is provided which is similar in many respects to the space blockers described above. The gap blocker 600 includes a body 602 having an upper locking portion 604 and a lower portion 606 that includes limb portions 608, 610. The body 602 has an upstream outboard portion 612 and a downstream outside roller coupling portion 614. The gap blocker 600 includes an extended convex surface 620 of the downstream outside roller coupling portion 614 and extended convex surfaces 622, 624 of contact portions 626, 628 of the limb portions 608, 610. The upstream outboard portion 612 has a rim 630 that makes contact with an upstream roller 632 and blocks a gap 632 between the upstream roller 632 and the downstream roller 634.The upper locking portion 604 has an upper surface 636 that is cupped relative to the upper surface portions of the rollers 632, 634 so that objects can be carried in directions 640 from the rollers 632, 634 without making contact with the space blocker 600. With regard to Figure 11, a space blocker 700 is provided that is similar in many respects to the space blockers described above. The space blocker 700 has a body 702 that includes an upper locking portion 704 and a lower portion 706 with limb portions 708, 710. The body 702 has a central axis 712 and is symmetrical about axis 712. The upper locking portion 704 includes portions of IA / t / ¿U¿ó / UOO IUO external roller couplings 720, 722 which are similar and include convex surfaces 724, 726 for making contact with rollers 728, 730. Likewise, end portions 708, 710 have convex surface portions 732, 734 which form line contacts with surfaces 736, 738 of rollers 728, 730. End portions 708, 710 are separated from roller surfaces 736, 738 except for convex surface portions 732, 734. With regard to Figure 12, a system 800 is provided that includes rollers 802, 804 having a gap 905 between them, a gap blocker 806 similar to the gap blocker 400 described above, and a driving member such as an O-ring 808. The O-ring 808 may be a single unitary member or may include multiple members such as a cable. In some embodiments, the O-ring 808 is made of a polymer material. The driving member may have other forms, such as a chain. Rollers 802, 804 each have a cylindrical outer surface 810 with an outside diameter 812 that supports the space blocker 806 and a grooved portion 814. The grooved portion 814 includes a groove 816 formed in the cylindrical outer surface 810, the groove 816 having a minimum outside diameter 818. The O-ring 808 loops around the rollers 802 and 804 such that the O-ring 808 has an upper portion 826 and a lower portion 828 that extend through the space 805. The O-ring 808 has a semicircular portion that extends into the groove 816 of each roller on opposite sides of the roller 802 and 804 from the space blocker 806. The semicircular portions of the O-ring 808 connect the upper and lower portions 826 and 828. The rollers 802 and 804 and the upper and lower portions 826 and 828 of the O-ring 808 form an opening 830 in the space 905. The O-ring 808 engages the rollers 802 and 804 by extending into the grooves 816 of the rollers. 802, 804 and coupling the surfaces 820 of the grooves 816. In one embodiment, roller 802 rotates in direction 822 by means of an O-ring connected to an upstream roller, such that roller 802 rotates in direction 822 to transport an object in a downstream direction 824. The O-ring 808 may be made of a resilient material and is under tension when it is stretched around rollers 802 and 804. The tension in the O-ring 808 tightly engages it with the surfaces 820 of the grooves 816. Rotation of roller 802 in direction 822 pushes the lower portion 828 of the O-ring 808 in direction 832, causing the O-ring 808 to rotate roller 804 in direction 834. Rotation of roller 802 in direction 822 also releases the upper portion 826 of the O-ring 808 away from the roller 802 and directs the upper portion 826 towards the roller 804. The space blocker 806 has a top surface 840, a bottom surface 842, and a height 844. The height 844 of the space blocker 806 is smaller than the outside diameter 812 of the roller outer surface 810 and the minimum outside diameter 818 of the groove 816 of the rollers 802, 804. The height 844 of the space blocker 806 is also smaller than a distance 850 between a portion of the bottom surface 852 of the top portion 826 of the butt joint 808 and a portion of the top surface 854 of the bottom portion 828 of the butt joint 808.In this way, the space blocker 806 can be extended laterally (in and out of the page in Figure 12) along the outer cylindrical surfaces 810 of the rollers 802, 804 to prevent objects from falling through the space 805, while also extending into the opening 830 formed by the O-ring 808 and the rollers 802, 804 in clearance from the O-ring 808. Because the space blocker 806 is in clearance from the O-ring 808, the O-ring 808 can transfer the rotation from the roller 802 to the roller 804 without interference from the space blocker 806. In some applications, the space blocker 806 is initially installed in space 805 with a portion of the space blocker 806 extending into the opening 830 formed by the O-ring 808 and the rollers 802, 804. In other applications, the space blocker 806 is installed in space 805, offset laterally from the grooves 816 and the O-ring 808. Over time, the space blocker 806 can be moved laterally into the opening 830 formed by the O-ring 808 and the rollers 802, 804 without interfering with the movement of the O-ring 808. With reference to Figure 13, a space blocker 900 is shown being inserted into a space 902 between rollers 904 and 906. The space blocker 900 is similar to the space blockers described earlier and includes a body 910 having an upper locking portion 912 and end portions 914 and 916. To position the space blocker 900 in the space 902, an outward portion 918 of the upper locking portion 912 and the end portion 916 are positioned against a cylindrical outer surface of roller 906, and the end portion 914 is deflected in direction 920 toward the end portion 916. With the end portion 914 deflected, the space blocker 900 can be rocked or advanced in direction 922 to position the contact portions 924, 926 of the extremity portions 914, 916 below the narrowest portion of space 902. With respect to Figure 14, each limb portion 914, 916 of the space blocker 900 includes a straight portion 930 extending downward from the upper blocking portion 912 and a curved portion 932 below the straight portion 930. The curved portion 932 has a faceted configuration that includes straight segments 934, 936 extending transversely to the straight portion 930 and to each other. The faceted configuration of the portions The IA / t / ¿U¿ó / UOO IUO limb 914, 916 makes the 910 body of the 900 space blocker easier to injection mold. Specifically, the 900 space blocker can be made from a molded plastic, and the faceted configuration of limb portions 914, 916 allows a metal mold portion to be pulled away from a plastic portion of the 900 space blocker without scratching or pulling the plastic when the metal mold portion retracts. Like other space blockers described herein, space blocker 900 can be removed from space 902 by lifting it upward on the upper locking portion 912. The cylindrical outer surfaces of rollers 904, 906 displace the end portions 914, 916 together relative to the upper locking portion 912, which temporarily narrows to a maximum width across the end portions 914, 916. Space blocker 900 continues to be lifted upward until the contact portions 924, 926 advance above the narrowest portion of space 902. The end portions 914, 916 resiliently displace again away from each other relative to the upper locking portion 912 once the end portions 914, 916 have been removed from space 902. Uses of singular terms such as a, an, are intended to cover both singular and plural, unless otherwise indicated herein or clearly contradicted by the context. The terms comprising, having, including, and containing are to be interpreted as indefinite terms. The phrase at least one of, as used herein, is intended to be interpreted in the disjunctive sense. For example, the phrase at least one of A and B is intended to cover A, B, or both A and B. Although particular embodiments of the present invention have been illustrated and described, it will be appreciated by those skilled in the art that numerous changes and modifications may occur, and the present invention is intended to cover all such changes and modifications which fall within the scope of the appended claims.

Claims

1. A gap blocker for a roller conveyor including rollers for transporting an object in a downstream longitudinal direction and a gap between them, the gap blocker comprising: a body to be positioned in the gap between the rollers; an upper blocking portion of the body to prevent an object being transported by the rollers from falling through the gap; limb portions of the body connected to the upper blocking portion at longitudinally spaced locations such that the limb portions have a gap between them extending in the longitudinal direction; the limb portions having an initial undeflected configuration with at least one of the limb portions having a first orientation with respect to the upper blocking portion;The limb portions of the body move relative to each other to decrease the distance across the space between the limb portions to facilitate the advancement of the body within the space; the limb portions of the body have an operating configuration with the body in the space, at least one of the limb portions has the first orientation with respect to the upper locking portion with the limb portions in the operating configuration; upper contact portions of the upper locking portion and lower contact portions of the limb portions to make contact with the rollers and support the body in the space;and outer surface portions of the body configured to be in clearance from the rollers with the body in space and the extremity portions in the operating configuration, the outer surface portions of the body being intermediate to the upper and lower contact portions along the rollers.; 2. The space blocker according to claim 1, further characterized in that the at least one limb portion includes upstream and downstream limb portions, each having the first limb orientation with respect to the upper blocking portion, with the limb portions in the initial undeviated configuration and operating configuration.

3. The space blocker according to claim 1, further characterized in that the limb portions include a first limb portion having a second orientation with respect to the upper locking portion with the limb portions in the initial non-deflected configuration and a third different orientation with respect to the upper locking portion with the limb portions in the operating configuration.

4. The space blocker according to claim 1, further characterized in that the limb portions include a resilient limb portion and at least one limb portion, the resilient limb portion being configured to be deflected with the body in space and the limb portions in the operating configuration.

5. The space blocker according to claim 1, further characterized in that the upper locking portion has a flat lower surface and the limb portions include straight portions hanging from the flat lower surface of the upper locking portion.

6. The space blocker according to claim 5, further characterized in that the straight portions are substantially perpendicular to the flat lower surface of the upper blocking portion.

7. The space blocker according to claim 1, further characterized in that the outer surface portions of the body are outer surface portions of the limb portions that are oriented towards the rollers with the body positioned in space.

8. The space blocker according to claim 1, further characterized in that the limb portions include the outer surface portions; wherein the lower contact portions of the limb portions include protrusions; and wherein the outer surface portions extend from the protrusions to the upper blocking portion.

9. The space blocker according to claim 1, further characterized in that the lower contact portions of the limb portions include convex surfaces to make contact with the rollers.

10. The space blocker according to claim 9, further characterized in that the limb portions include the outer surface portions of the body, the outer surface portions comprising concave surface portions.

11. The space blocker according to claim 1, further characterized in that the upper blocking portion includes an upper blocking surface to extend longitudinally between the rollers; wherein the body includes an intermediate portion below the upper blocking portion, the upper blocking portion being configured to fit in a narrower part of the space in a longitudinal direction between the rollers; wherein the body has a dimension in the longitudinal direction that decreases continuously as the body extends from the upper contact portions to the intermediate portion.

12. The space blocker according to claim 11, IA / t / ¿U¿ó / UOO IUO, further characterized in that the limb portions include the intermediate body portion; wherein the lower contact portions of the limb portions include protrusions; and wherein the limb portions have a dimension through the limb portions in the longitudinal direction that increases continuously as the limb portions extend downwards away from the intermediate portion.

13. The space blocker according to claim 1, further characterized in that the lower contact portions of the limb portions are configured to form lateral line contacts with the rollers.

14. The space blocker according to claim 1, further characterized in that the body has opposite lateral sides, a length extending laterally between the lateral sides, and a cross-section perpendicular to the length that is uniform from one lateral side to the other.

15. The space blocker according to claim 1, further characterized in that the body is made of plastic.

16. The space blocker according to claim 1, further characterized in that the body has a one-piece unitary construction.

17. The space blocker according to claim 1, further characterized in that the limb portions are longitudinally aligned.

18. The space blocker according to claim 1, further characterized in that the limb portions include a pair of upstream limb portions and the at least one limb portion includes a downstream limb portion.

19. The space blocker according to claim 1, further characterized in that the extremity portions each include a base portion connected to the upper locking portion and a free end portion opposite the base portion.

20. The space blocker according to claim 1, further characterized in that the body has an upstream surface oriented towards a roller upstream of the rollers and a downstream surface oriented towards a roller downstream of the rollers; wherein the upstream and downstream surfaces extend respectively from the upper contact portions of the upper blocking portion to the lower contact portions of the end portions; wherein the upstream and downstream surfaces of the body include the outer surface portions; and wherein the upstream and downstream surfaces of the body are in clearance from the rollers with the body in space and the end portions in the operating configuration.

21. A gap blocker for a roller conveyor including rollers for transporting an object in a downstream longitudinal direction and a gap between the rollers, the gap blocker comprising: a body to be positioned in the gap; an upper blocking portion of the body having upstream and downstream contact portions configured to make contact with the rollers above a narrower portion of the gap; a resilient lower portion of the body having upstream and downstream lower protrusions to make contact with the rollers, the resilient lower portion of the body having a deflected configuration wherein the resilient lower portion is narrower than the narrower portion of the gap to allow the resilient lower portion of the body to advance through the narrower portion of the gap and into an operating position below the narrower portion of the gap;The resilient lower portion of the body has a non-deflected configuration wherein the upstream and downstream lower protrusions are below the narrowest portion of the space; and upstream and downstream surface clearance portions of the resilient lower portion of the body intermediate to the upper locking portion of the body and the upstream and downstream lower protrusions along a height of the body, the upstream and downstream surface portions of the resilient lower portion of the body are configured to be in clearance of the rollers with the body in the operating position.

22. The space blocker according to claim 21, further characterized in that the upstream and downstream lower protrusions are configured to form lateral line contacts with the rollers.

23. The space blocker according to claim 21, further characterized in that the upstream and downstream lower protrusions include convex surface portions; and wherein the upstream and downstream clearance surface portions are concave.

24. The space blocker according to claim 21, further characterized in that the upstream and downstream lower projections of the resilient lower portion of the body include contact surfaces that make contact with the rollers; wherein the resilient lower portion of the body includes joints between the contact surfaces and the clear surface portions upstream and downstream of the resilient lower portion of the body; and wherein the joints are configured to be in clear with the rollers with the body in the operating position.

25. The space blocker according to claim 21, further characterized in that the resilient lower body portion includes limb portions including upstream and downstream lower protrusions and upstream and downstream clear surface portions.

26. The space blocker according to claim 21, further characterized in that the resilient lower body portion includes limb portions IA / t / ¿U¿ó / UOO IUO connected to the upper locking portion at longitudinally separated locations such that the limb portions have a space extending longitudinally between them.

27. The space blocker according to claim 26, further characterized in that the limb portions include upstream and downstream lower protrusions and upstream and downstream clear surface portions.

28. The space blocker according to claim 21, further characterized in that the resilient lower portion of the body includes a pair of limb portions comprising upstream and downstream lower protrusions and upstream and downstream clear surface portions; and wherein at least one of the limb portions has a first orientation with respect to the upper blocking portion with the resilient lower portion of the body in both the deflected and non-deflected configurations.

29. The space blocker according to claim 21, further characterized in that the downstream upper contact portion and the downstream lower protrusion are separated along a first arc having a first radius of curvature that is more than half the height of the space blocker with the resilient lower portion in the undeviated configuration thereof.

30. The space blocker according to claim 29, further characterized in that the upstream upper contact portion and the upstream lower protrusion are separated along a second arc having a second radius of curvature that is more than half the height of the space blocker with the resilient lower portion in the undeviated configuration thereof.

31. The space blocker according to claim 21, further characterized in that the body has opposite side sides, a length extending laterally between the side sides, and a cross-section perpendicular to the length that is uniform from one side side to the other.

32. The space blocker according to claim 21, further characterized in that the body has a one-piece unitary construction.

33. A roller conveyor comprising: rollers rotating to transport an object in a downstream longitudinal direction, the rollers having outside diameters; a space between the rollers; a drive member extending around the rollers to transfer rotation from one roller to the other roller, the drive member having upper and lower portions extending across the space separated from each other, the drive member having a distance between the upper and lower portions of the drive member; a space blocker supported in the space by the first and second rollers, the space blocker having an upper blocking portion above a narrower portion of the space, a lower portion below the narrower portion of the space, and an intermediate portion extending into the narrower portion of the space;The space blocker has a height that is less than the outside diameter of either of the rollers and that is less than the distance between the upper and lower portions of the driving member so that the space blocker is in clearance with the driving member.

34. The roller conveyor according to claim 33, further characterized in that the rollers and the drive member form an opening in the space and the space blocker is dimensioned to extend into the opening.

35. The roller conveyor according to claim 33, further characterized in that the driving member is a polymeric tonca joint.

36. The roller conveyor according to claim 33, further characterized in that the rollers have circular outer surface portions receiving the drive member, the circular outer surface portions having respective outside diameters; and wherein the height of the space blocker is less than the minimum outside diameter of at least one of the circular outer surface portions.

37. The roller conveyor according to claim 33, further characterized in that the rollers include grooved portions that receive the drive member, the grooved portions having minimum outside diameters; and wherein the height of the space blocker is less than the minimum outside diameter of at least one of the grooved portions.

38. The roller conveyor according to claim 33, further characterized in that the rollers can rotate about respective axes; wherein the upper locking portion of the space blocker includes a first contact portion making contact with a first roller of the rollers and a second contact portion making contact with a second roller of the rollers, the first and second contact portions making contact with the first and second rollers above the narrower portion of the space; wherein the first contact portion is intermediate between the first roller and the upper portion of the driving member in a first radial direction from the axis of rotation of the first roller; and wherein the second contact portion is intermediate between the second roller and the upper portion of the driving member in a second radial direction from the axis of rotation of the second roller.

39. The roller conveyor according to claim 38, further characterized in that the lower portion of the space blocker includes a third contact portion making contact with the first roller and a fourth contact portion making contact with the second roller, the third and fourth contact portions making contact with the first and second rollers below the narrower portion of the space; wherein the third contact portion is intermediate to the first roller and the lower portion of the driving member in a third radial direction from the axis of rotation of the first roller; and wherein the fourth contact portion is intermediate to the second roller and the lower portion of the driving member in a fourth radial direction from the axis of rotation of the second roller.

40. The roller conveyor according to claim 39, further characterized in that the first and third radial directions extend to a first angle of more than 45 degrees; and wherein the second and fourth radial directions extend to a second angle of more than 45 degrees.

41. The roller conveyor according to claim 33, further characterized in that the upper portion of the drive member has a first longitudinal length between the rollers; and wherein the upper blocking portion of the gap blocker includes an upper blocking surface to prevent the object from falling through the gap, the upper blocking surface having a second longitudinal length shorter than the first longitudinal length of the upper portion of the drive member.

42. The roller conveyor according to claim 33, further characterized in that the lower portion of the space blocker includes limb portions having an installation configuration in which the limb portions are closer together to allow the limb portions to be advanced into the space and an operating configuration in which the limb portions are further apart.

43. The roller conveyor according to claim 33, further characterized in that the space blocker has limb portions including the intermediate portion and the lower portion of the space blocker; and wherein the limb portions are connected to the upper blocking portion at longitudinally separated locations so that there is a longitudinal space between the limb portions.

44. The roller conveyor according to claim 43, further characterized in that the upper locking portion includes upper contact portions that make contact with the rollers above the narrower portion of the space and the lower end portions include protrusions that make contact with the rollers below the narrower portion of the space.

45. The roller conveyor according to claim 33, further characterized in that the intermediate portion of the space blocker is separated from the rollers during operation of the roller conveyor.

46. The roller conveyor according to claim 33, further characterized in that the drive member is made of a polymer material and the space blocker is made of a plastic material.

47. A roller conveyor comprising: upstream and downstream rollers, the upstream and downstream rollers having outside diameters; a drive belt for making contact with the upstream and downstream rollers, the drive belt being movable to rotate the upstream and downstream rollers and cause the upstream and downstream rollers to carry the object in a downstream longitudinal direction; a gap between the upstream and downstream rollers;a space blocker supported in the space by upstream and downstream rollers, the space blocker having an upper blocking portion above a narrower portion of the space, the space blocker having a lower upstream member including an upstream free end portion to make contact with the upstream roller and a lower downstream member including a downstream free end portion to make contact with the downstream roller; wherein the lower upstream member and the lower downstream member can be offset towards each other with respect to the upper blocking portion into an offset configuration to facilitate removal of the space blocker from the space;and wherein the space blocker has a height that is less than the outside diameter of either of the upstream and downstream rollers so that the space blocker is in clearance with the drive belt.

48. The roller conveyor according to claim 47, further characterized in that the upstream free end includes an upstream protrusion for making contact with the upstream roller below the narrower portion of the space and the downstream free end includes a downstream protrusion for making contact with the downstream roller.

49. The roller conveyor according to claim 47, further characterized in that the lower upstream member and the lower downstream member are connected to the upper locking portion of the space blocker at longitudinally separated locations such that the lower upstream and downstream members have a space between them extending in the longitudinal direction.

50. The roller conveyor according to claim 47, further characterized in that the space blocker has a vertical axis and the space blocker is symmetrical about the vertical axis.

51. The roller conveyor according to claim 47, further characterized in that the upstream free end includes an upstream lower surface having a first distance from the drive belt; and wherein the downstream free end portion includes a downstream lower surface having a second distance from the drive belt which is the same as the first distance.

52. The roller conveyor according to claim 47, further characterized in that the drive belt includes an upper race for making contact with the upstream and downstream rollers, a lower race below the upper race and separated from the rollers, and return portions connecting the upper and lower races.

53. The roller conveyor according to claim 47, further characterized in that it also comprises a stationary frame, the upstream and downstream rollers are rotatably mounted on the stationary frame, and the drive belt is movable relative to the stationary frame and the upstream and downstream rollers.

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