Self-winding belt drive

Abstract

The present disclosure includes a belt drive mechanism that can be used to pay out or retract a belt to or from a belt-operated system (or belt-driven system). The mechanism features a self-winding spool that can automatically wind or unwind a portion of the belt as the portion of the belt is withdrawn or fed into the belt-operated system. A second rotating shaft (idler shaft) having one or more sheaves (e.g., pulleys or rollers) can be rotatably coupled to the capstan via the belt and can be utilized to drive additional mechanisms within the belt drive mechanism, such as a take-up mechanism.

Description

[Technical Field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 129,695, filed December 23, 2020, and U.S. Utility Patent Application No. 17 / 335,269, filed June 1, 2021, which are incorporated herein in their entireties for all purposes.

[0002] Technical Field FIELD OF THE DISCLOSURE The present disclosure relates generally to self-rewinding belt drives. [Background technology]

[0003] background Modern belts have many desirable properties. They are lightweight, low maintenance, and can have high strength under tension. Many new and old applications for modern belts are now being adapted.

[0004] overview Generally, the present disclosure includes a self-rewinding belt drive mechanism including a capstan configured to retract a belt from a belt-driven system or unwind a belt to a belt-driven system, and an idler shaft coupled to the capstan via a belt. The idler shaft rotates in a retraction direction when the capstan rotates in a retraction direction and in an unwinding direction when the capstan rotates in an unwinding direction. The idler shaft includes a first end configured to receive one or more wraps of the belt, a second end coupled to a first one-way locking bearing, and a first gear connected to the first one-way locking bearing. The first one-way locking bearing engages when the idler shaft rotates in the retraction direction, causing the first gear to rotate with the rotating idler shaft. The first one-way locking bearing disengages when the idler shaft rotates in the unwinding direction, allowing relative motion between the first gear and the idler shaft. The belt drive mechanism further includes a spool that receives or unwinds a portion of the belt, the spool including an outer hub configured to rotate to wind or unwind the portion of the belt around the outer hub, and a second gear frictionally engaged with the outer hub, the second gear configured to be driven by the first gear such that the first gear drives the second gear, and causes the outer hub to rotate in a direction to wind up the portion of the belt when the idler shaft rotates in a retracting direction.

[0005] Implementations may optionally include one or more of the following features. In some implementations, the spool includes an inner hub connected to the central shaft via a second one-way locking bearing. The second one-way locking bearing allows the inner hub to rotate relative to the central shaft when the outer hub rotates in a direction to wind a portion of the belt. The second one-way locking bearing prevents rotation between the inner hub and the central shaft when the outer hub rotates in a direction to unwind a portion of the belt. The inner hub can be frictionally engaged with the outer hub such that the outer hub rotates relative to the inner hub when rotating in a direction to unwind a portion of the belt, overcoming the frictional force between the inner and outer hubs.

[0006] In some implementations, the first gear of the belt drive mechanism is a bevel gear and the second gear is a ring gear.

[0007] In some implementations, the second gear is configured to overdrive the outer hub and rotates at least 1.5% faster than the outer hub.

[0008] In some implementations, the belt passes through the belt-actuated system and returns to the belt drive mechanism such that both the first and second ends of the belt are within the belt drive mechanism, and retracting and unretracting the belt actuates the belt-actuated system.

[0009] In some implementations, the belt-actuated system includes a block and tackle system that expands or contracts as the belt is retracted from or paid out of the belt-actuated system.

[0010] In some implementations, at least one end of the belt is electrically connected to a circuit within the belt drive mechanism, the circuit being capable of measuring at least one electrical parameter associated with the belt.

[0011] In some implementations, the belt drive mechanism includes an encoder wheel including an outer surface with ribs, the ribs engaging notches in the belt. The shaft of the encoder wheel can be connected to the encoder.

[0012] This disclosure describes a belt drive mechanism that can be used to pay out or retract a belt from a belt-driven system (or belt-driven system). The mechanism features a self-rewinding spool that can automatically retract or unwind a portion of the belt as the belt is paid out or supplied to the belt-driven system. Belt-driven systems can have many advantages over other similar systems. For example, belt-driven linear actuators require less maintenance, are lighter, and are capable of more cycles than similar hydraulic linear actuators. Many belt drive mechanisms include a capstan that can receive one or more wraps or partial wraps of the belt and provide rotational force to retract / retract or retract the belt. The capstan can be powered by an electric motor, for example, via a reduction gear set or a hydraulic motor, among other things. In some implementations, a second rotating shaft (e.g., an idler shaft) with one or more sheaves (e.g., pulleys or rollers) can be rotationally coupled to the capstan via the belt and can be utilized to drive additional mechanisms within the belt drive mechanism, such as a take-up mechanism described below.

[0013] Implementations may include one or more of the following advantages: In one implementation, the belt drive mechanism includes a friction-driven spool, which allows the rotational speed of the spool to be varied independently of the belt drive capstan and idler shaft. This ensures that tension is maintained throughout the operation of the belt drive mechanism without requiring variable gearing or other complex systems to manage the rotational speeds of various components. The system of one-way locking bearings and friction surfaces results in a self-rewinding mechanism that is mechanically simple, compact, yet robust throughout the operating range of the belt drive mechanism.

[0014] During constant speed winding, the effective diameter of the spool will increase as the belt wraps around the spool. Similarly, the effective diameter of the spool will decrease during unwinding. Because the diameter is not constant, the rotational speed of the spool can be varied to continue retracting (or unwinding) the belt at a constant speed. As described in more detail below, the spool can be driven by an idler shaft through frictional interaction, allowing for a difference in rotational speed between the spool and the idler shaft. For example, the idler shaft can have a bevel or miter gear fixed at one end that engages a ring gear that frictionally engages the side of the spool. The gearing between the bevel gear and the ring gear can cause the spool to rotate faster than the required rotation of the spool as the belt is wound in. The ring gear can be pressed against the side of the spool (e.g., via a spring), and the rotating ring gear can frictionally drive the spool at a slower speed. The slower speed can be limited by belt tension. As the spool fills with belt and its effective diameter increases, it can slow down while still being frictionally driven by the rotating ring gear.

[0015] During unwinding, tension provided by the belt can provide the power to unwind the spool. However, if the spool rotates freely in the unwinding direction, additional problems can arise. For example, because the spool gains angular momentum, it may tend to continue rotating after the capstan has stopped, potentially introducing slack into the system and causing the capstan to lose traction with the belt. A second mechanism can be provided that applies rotational friction to the spool that is applied only when the spool is unwinding, thus preventing the introduction of slack from a freely rotating spool. In one embodiment, the spool can include an outer hub around which the belt wraps and an inner hub that frictionally engages the outer hub, such that the outer hub must overcome a predetermined amount of friction to rotate relative to the inner hub. In this implementation, the inner hub can be attached to the shaft via a one-way locking bearing, which allows the inner hub to rotate about the shaft in one direction (e.g., when the spool is winding the belt) and prevents movement of the inner hub relative to the shaft in a second direction (e.g., when the spool is unwinding). In this way, during unwinding, the inner hub remains stationary while the outer hub rotates around the inner hub via the belt, overcoming friction between the inner and outer hubs.

[0016] The details of one or more implementations of the subject matter herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims.

[0017] DESCRIPTION OF THE DRAWINGS In order to more clearly describe the technical solutions in the implementations of the present specification or existing technologies, the following briefly describes the accompanying drawings necessary for describing the implementations or existing technologies. Obviously, the accompanying drawings in the following description only show some implementations of the present specification, and those skilled in the art can still derive other drawings from these accompanying drawings without creative efforts. [Brief explanation of the drawings]

[0018] [Figure 1A] FIG. 1 shows a side view of a linear actuator including a belt drive mechanism and a belt actuated mechanism. [Figure 1B] FIG. 1B shows a perspective view of the linear actuator of FIG. 1A. [Figure 2] FIG. 2 is a right side view of the belt drive mechanism of the linear actuator of FIGS. 1A and 1B. [Figure 3] FIG. 2 is a left side view of the belt drive mechanism of the linear actuator of FIGS. 1A and 1B. [Figure 4] FIG. 2B illustrates a belt of the belt drive mechanism of the linear actuator of FIGS. 1A and 1B. [Figure 5] 1C is a cross-sectional view of a retaining belt and tension roller of the belt drive mechanism of the linear actuator of FIGS. 1A and 1B. FIG. [Figure 6] FIG. 2 is a cross-sectional view of a self-winding mechanism of the belt drive mechanism of the linear actuator of FIGS. 1A and 1B. [Figure 7A] 1 shows a manual crane illustrating an alternative implementation of a belt drive mechanism. [Figure 7B] 1 shows a manual crane illustrating an alternative implementation of a belt drive mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0019] Like reference numbers and designations in the various drawings indicate like elements. Detailed Description This disclosure describes a belt drive mechanism that can be used to pay out or retract a belt from a belt-driven system (or belt-driven system). The mechanism features a self-rewinding spool that can automatically retract or unwind a portion of the belt as the belt is paid out or supplied to the belt-driven system. Belt-driven systems can have many advantages over other similar systems. For example, belt-driven linear actuators require less maintenance, are lighter, and are capable of more cycles than similar hydraulic linear actuators. Many belt drive mechanisms include a capstan that can receive one or more wraps or partial wraps of the belt and provide rotational force to retract / retract or retract the belt. The capstan can be powered by an electric motor, for example, via a reduction gear set or a hydraulic motor, among other things. In some implementations, a second rotating shaft (e.g., an idler shaft) with one or more sheaves (e.g., pulleys or rollers) can be rotationally coupled to the capstan via the belt and can be utilized to drive additional mechanisms within the belt drive mechanism, such as a take-up mechanism described below.

[0020] In order to help those skilled in the art better understand the technical solutions in this specification, the following will clearly and comprehensively describe the technical solutions in the implementations of this specification with reference to the accompanying drawings in the implementations of this specification.Obviously, the implementations described are only some implementations, not all of the implementations of this specification.All other implementations obtained by those skilled in the art based on one or more implementations of this specification without creative efforts shall fall within the protection scope of the implementations of this specification.

[0021] 1A and 1B illustrate an exemplary linear actuator 100 including a belt drive system 101 coupled to a belt-actuated mechanism 102. As shown, a linear actuator with a belt drive mechanism 101 can take a form factor similar to a standard hydraulic cylinder. In this example, the belt-actuated mechanism 102 can include one or more blocks and tackles with multiple free spans of belt therebetween. Pulling the belt from the belt-actuated mechanism 102 can retract the belt. Similarly, paying out the belt from the belt-actuated mechanism 102 can extend the belt. As shown, for simplicity, a single belt drive mechanism 101 is applied, applying power in only one direction (e.g., the retraction direction) and relying on gravity or other forces to extend the belt-actuated mechanism 102. In some implementations, multiple belt drive mechanisms 101, or belt-actuated mechanisms 102 of different configurations, can be provided to accommodate bidirectional application of power (e.g., powered extension / retraction). Additionally, while illustrated as a linear actuator, the belt-actuated mechanism 102 can be any system configured to operate using a belt. The present disclosure contemplates many belt-actuated mechanisms, such as linear actuators, rotary actuators, cranes, pumps, conveyors, and other belt-actuated systems.

[0022] FIG. 2 is a right side view of belt drive mechanism 101. Some structural and housing components are not shown in FIG. 2 for clarity. A motor and gearbox (e.g., an electric motor) or other device can rotate driven shaft 202, which provides power for operation of belt drive mechanism 200. Capstan 204 can be configured to accept multiple wraps of belt 218, with each wrap providing more friction and increasing the amount of tension capstan 204 can apply to belt 218. As shown in FIG. 2, belt 218 completes three half wraps around capstan 204 and the remaining three half wraps pass around idler shaft 206. The space between idler shaft 206 and capstan 204 creates multiple free spans of belt, which minimizes the twist rate and fleet angle of belt 218 to reduce wear. An idler shaft 206, which may share rotation with the capstan 204, may be supported by one or more bearings, causing the idler shaft 206 to rotate as the belt 218 passes around it. In this manner, the idler shaft 206 and the driven shaft 202 generally rotate in the same direction, although their axes need not coincide. A bevel gear 208 may be connected to one end of the idler shaft. While shown as a bevel gear, any suitable gear (e.g., spur gear, screw gear, worm gear, miter gear, etc.) may be used.

[0023] The bevel gear 208 engages a ring gear 210 that frictionally engages a spool 212, such that rotation of the bevel gear 208 causes rotation of the ring gear 210, which provides a frictional force that rotates the spool 212. As shown, the capstan 204 can rotate in a retraction direction to remove the belt 218 from the belt-actuated mechanism 102, or in an unreeling direction to allow the belt 218 to enter the belt-actuated mechanism 102. As shown in this example, removing the belt 218 from the belt-actuated mechanism 102 contracts the associated blocks and tackle, shortening the span of the belt between the blocks within the belt-actuated mechanism 102. Unreeling or entering the belt 218 into the belt-actuated mechanism 102 can lengthen the belt-actuated mechanism 102 or increase the span distance within the belt-actuated mechanism 102.

[0024] In some implementations, the bevel gear 208 is connected to the idler shaft 206 via a one-way locking bearing, which allows rotation in one direction between the idler shaft 206 and the bevel gear, but prevents rotation in a second direction between the idler shaft 206 and the bevel gear. For example, when the capstan 204 (and similarly the idler shaft 206) rotates in a retraction direction to retrieve the belt 218 from the belt-actuated mechanism 102, the one-way locking bearing in the bevel gear engages, allowing the bevel gear to rotate with the idler shaft. Thus, when the capstan 204 rotates in the retraction direction, it drives the spool via the idler shaft 206, the bevel gear 208, and the ring gear 210.

[0025] In the illustrated example, the belt 218 passes through the belt actuated mechanism 102 such that both ends of the belt 218 are located within the belt drive mechanism 101. A first end of the belt 218 can be connected to an electrical connector 216 that can be used to monitor electrical parameters associated with the belt 218 (e.g., continuity of support structures within the belt 218, resistance, capacitance, reflectance measurements, etc.). A second end of the belt 218 can be attached to a spool 212 that can be wound and unwound and capture a portion of the belt 218 as it is unwound from the belt actuated mechanism 102. In some implementations, the belt 218 in a belt-driven system can include internal wiring or circuitry or can be constructed to have electrical characteristics that change under load. For example, belts often have conductive reinforcing structures throughout. In this example, the belt drive system can perform a continuity check that measures the impedance or resistance between one or more ends of the conductive reinforcing structures to determine whether they have broken, thus compromising the structural integrity of the belt 218. In another example, continuity between the internal conductive material of the belt 218 and the housing of the drive mechanism can be measured. Continuity between the internal conductive material of the belt 218 and the housing can indicate that a portion of the belt 218 is worn or damaged and that the belt 218 should be replaced or repaired. In some implementations, the belt 218 includes a material with different electrical properties under different loads. For example, as the tension of the belt 218 increases, its resistance or impedance may also increase. Electrical connections at one or both ends of the belt 218 can be provided to enable measurement of one or more electrical properties that can be used to determine the condition of the belt 218 (e.g., tension, temperature, configuration, etc.).

[0026] FIG. 3 is a left side view of the belt drive mechanism 101. Various structural components are not shown for simplicity. The spool 213 is attached to the inner hub 302. In some implementations, the inner hub 302 and the spool 213 are frictionally engaged such that the spool 213 can rotate around the inner hub 302 if the frictional force between the inner hub 302 and the spool 213 is overcome. In some implementations, the spool 213 is spring-loaded against a wear surface of the inner hub 302. The inner hub 302 may be attached to a fixed shaft via a one-way locking bearing, which may be similar or different from the one-way locking bearing described above with reference to the bevel gear 208. As the spool 213 rotates in the winding direction, driven by the ring gear 210, the inner hub can rotate with the spool 213, minimizing friction and allowing the spool to wrap around the belt 218. During an unwinding operation, when the capstan 204 rotates in the unwinding direction, the bevel gear 208 rotates freely, independently of the idler shaft 206, allowing the spool 212 to rotate in the unwinding direction. If the spool 212 accumulates significant angular momentum in the unwinding direction, it may continue to unwind the belt 218 after the capstan stops rotating, thus introducing slack into the system and potentially causing a loss of control of the belt drive mechanism 101 or other problems. To ensure that the spool 213 stops when the capstan 204 stops, the inner hub 302 and its associated one-way bearing are locked to the central shaft, preventing the inner hub 302 from rotating. During unwinding, the spool rotates 213 around the inner hub 302, and the tension in the belt 218 overcomes the friction between the spool 213 and the inner hub 302.

[0027] 3 also shows an anchor 304 that secures one end of the belt 218 to the belt drive mechanism 101. The anchor is located at the high tension end of the belt 218 and provides a fixed reference point for the belt 218 within the belt drive mechanism 101. The belt 218 passes from the anchor 304, over a tension sensor 306, and into the belt actuated mechanism 102. A more detailed description of the belt's path through the belt drive mechanism 101 and the belt actuated mechanism 102 is discussed below with respect to FIG.

[0028] Continuing to refer to FIG. 3 , in some implementations, the belt drive mechanism 101 includes an encoder wheel 326. The encoder wheel 326 can have ridges or protrusions on its outer surface configured to mate with notches or grooves in the belt 218 to ensure that the belt 218 does not slide across the encoder wheel 326. The encoder wheel 326 can be attached to an encoder to provide a precise position indication of the encoder wheel 326, and therefore, of the belt 218. The belt-actuated mechanism 102 can have a position directly related to the belt position. For example, if the belt-actuated mechanism 102 is part of a linear actuator, the distance the actuator has extended or retracted can be determined directly from the encoder position.

[0029] The tension sensor 306 can have a sheave that deflects the belt 218, as shown in FIG. 3. As the sheave on the tension sensor 306 deflects the belt 218, a reaction force proportional to the tension in the belt 218 is generated on the sheave. The sheave can be fixed to a translation component (e.g., a piston or cylinder) that is spring-biased against the reaction force. In this configuration, as the tension in the belt 218 increases, the reaction force will increase, compressing the spring and causing the sheave to translate (upward in the illustration provided in FIG. 3). A position indicator on the translation component can measure the translation of the sheave and translation component, which is proportional to the tension in the belt 218. The position indicator can be electronic (e.g., one or more Hall Effect sensors or strain gauges) or mechanical (e.g., painted or engraved position indicators). The tension sensor 306 can be used for automatic safety operations (eg, emergency payout) or to calculate expected wear and determine the useful life of the belt 218 or belt drive.

[0030] FIG. 4 shows the belt 218 and belt-actuated mechanism 102 of the belt drive mechanism 101. Referring to FIGS. 2-4, a first end 402 of the belt 218 can be connected to an electrical connector (e.g., the belt connector 206 described with reference to FIG. 2) and attached to a circuit board or other device within the belt drive mechanism 101. The belt 218 can then pass through an anchor that forms a high-friction anchor flexure 404, ensuring that the first end 402 of the belt 218 is not under tension and that the belt 218 is secured around the anchor flexure 404. The belt 218 can then pass over a tension sensor (e.g., the tension sensor 306 described with reference to FIG. 3) to form a tension sensor flexure 406.

[0031] The belt 218 then enters the belt actuated mechanism at belt actuated mechanism entrance 408. The illustrated example depicts the belt 218 passing through a block and tackle system with several free spans within the belt actuated mechanism. The belt 218 then returns to the belt drive mechanism via belt actuated mechanism return 410, where it passes around the capstan and idler shafts, making one or more bends around both the capstan shaft 412 and the idler shaft 414. Following its final wrap around the capstan shaft 412 and the idler shaft 414, the belt 218 enters spool winding 416, where it is wound or unwound according to the operation of the belt drive mechanism. A second end 418 terminates the belt 218 and can be secured to the spool.

[0032] FIG. 5 shows a cross-sectional view of a belt drive mechanism 101 including a retaining belt and tension roller that can be used as a slack remover. In some belt-driven systems, it is desirable to minimize slack in the system. In other words, it is preferable for the belt 218, or a portion of the belt 218, to be kept under tension at all times. In a system having two shafts, one powered and one driven by the belt 218 (e.g., a capstan and idler shaft), a system can be provided to ensure positive tension on the belt 218. A first retaining device, such as a belt or roller, can press the belt 218 against a portion of the capstan, ensuring traction between the capstan and the belt 218 regardless of belt tension. A second retaining device can apply pressure to the belt 218 on the idler shaft, ensuring positive contact with the idler shaft. In this way, in the event of slack, the capstan can extract slack from between the first and second retaining devices, and thus the idler gear rotates with the capstan to ensure any remaining slack is removed from the system.

[0033] A loose main belt 218 in a belt drive mechanism can cause problems during operation. For example, the loose belt 218 can come off one or more sheaves or fold over on itself, blocking and jamming the belt drive mechanism. Additionally, a loose or slack belt 218 can reduce the amount of friction or traction between the capstan and the belt 218, preventing the capstan from moving the belt 218. In this case, the idler shaft can rotate out of agreement with the capstan because positive friction is not guaranteed.

[0034] Still referring to FIG. 5 , the retaining belt 502 can be a separate belt from the main belt 218 of the belt drive mechanism and can be positioned to be under a predetermined tension and to apply a force to one or more wraps of the main belt 218 on the capstan 204. In some implementations, the retaining belt 502 applies pressure to the bottom tension wrap of the main belt 218 on the capstan 204. This pressure ensures positive contact, and therefore positive traction, between the main belt 218 and the capstan 204, even when the main belt 218 is in a relaxed state. In addition to the retaining belt 502, a tension roller 504 can be positioned to apply pressure to one or more wraps of the belt 218 on the idler shaft 206, ensuring positive contact between the belt 218 and the idler shaft at the tension roller 504. In situations where the main belt 218 is loose or slack exists, the retaining belt 502 provides traction on a portion of the capstan 204, allowing the capstan 204 to rotate reliably and take the slack out of the span between the capstan 204 and the tension roller 504. Once the slack is removed from the span between the capstan 204 and the tension roller 504, the idler shaft 206 begins to rotate via the main belt 218, thus taking the slack out of the rest of the system.

[0035] FIG. 6 shows a cross-sectional view of a portion of the belt drive mechanism 101 shown in FIG. 1, including a self-rewinding mechanism 600. The idler shaft 206 is rotatable about the idler axis 414 in either the retraction or retraction direction and is driven by the belt 218 via a capstan. The idler shaft 206 is connected to the bevel gear 208 via a one-way bearing 604A. The one-way bearing 604A allows rotation between the bevel gear 208 and the idler shaft 206 when the idler shaft rotates relative to the bevel gear 208 in the retraction direction. The one-way bearing 604A prevents rotation between the idler shaft 206 and the bevel gear 208 in the retraction direction. While shown as a bevel gear 208, any suitable gear type or one-way locking mechanism can be used. The bevel gear 208 engages the ring gear 210, which is in frictional contact with the spool 212. A spring 608A ensures positive engagement between the ring gear 210 and the spool 212. The spool 212 frictionally engages the inner hub 302. The inner hub 302 and spool 212 may be urged together by a spring 608B. A wear surface (e.g., a brake pad or friction disc) may be provided between the spool 212 and inner hub 302 to ensure a desired level of friction between the inner hub 302 and spool 212 is achieved. The inner hub 302 may be attached to the hub axle 606 via a one-way locking bearing 604B. The one-way locking bearing 604B allows rotation of the inner hub 302 about the hub axle 606 in the winding direction (as indicated by the arrow on the spool axle 610) but prohibits rotation of the inner hub 302 about the hub axle 606 in the unwinding direction.

[0036] The self-rewinding mechanism serves two functions: it ensures that tension is maintained in the belt 218 as it winds onto the spool during the retraction operation of the belt drive mechanism (e.g., the belt drive mechanism 101 shown and described with reference to FIG. 2 ), and it also maintains tension in the belt 218 during the unretraction operation.

[0037] During a retraction operation, the belt drive mechanism retracts the belt 218 from the belt actuated mechanism (e.g., belt actuated mechanism 102 of FIG. 1). The idler shaft 206 rotates about the idler axis 414 and engages the one-way locking bearing 604A, causing the bevel gear 208 to rotate with the idler shaft 206. The retraction direction is as indicated by the arrow on the idler axis 414.

[0038] As the bevel gear 208 rotates, it drives the ring gear 210, exerting a torsional force on the spool 212 and rotating it about the spool axis 610 in the reeling direction, as indicated by the arrow on the spool axis 610. As the spool 212 reels in an increasing amount of belt 218, the effective diameter of the spool 212 increases as the belt 218 overlaps. To maintain a constant retraction speed of the belt drive mechanism, the spool 212 must be slowed down. In other words, the rotational speed of the spool 212 must be faster when the spool 212 is empty than when the spool 212 is full. To compensate for this variable speed requirement of the spool 212, the ring gear 210 is not directly attached to the spool 212, but rather rotates along the side of the spool 212 to provide a frictional force. The gearing between the bevel gear 208 and the ring gear 210 can be selected so that the ring gear overdrives (e.g., rotates faster) the spool 212 throughout the entire operating range of the spool 212. In some implementations, the ring gear 210 overdrives the spool 212 by 1.5% when the spool 212 is empty and by 15% when the spool 212 is full. The overdriven ring gear 210 ensures that the spool 212 applies tension to the belt 218 throughout the retraction motion.

[0039] During retraction, when the spool 212 is rotating in the retraction direction, the inner hub 302 is free to rotate about the hub axle 606. The spool 212 and inner hub 302 rotate together.

[0040] During the unwinding operation, tension must still be maintained in the belt 218. During unwinding, the idler shaft 206 rotates in the unwinding direction (opposite the arrow shown on the idler axle 414), and the one-way bearing 604A disengages, allowing the idler shaft 206 and bevel gear 208 to rotate independently. This allows the idler shaft 206 and spool 212 to rotate at different speeds, which is necessary to unwind the belt 218 from the spool 212. The one-way bearing 604B engages, preventing rotation of the inner hub 302 in the unwinding direction (opposite the arrow shown on the spool axle 610). The tension in the belt 218 pulls the spool 212 around the inner hub 302, overcoming friction between the inner hub 302 and the spool 212. Because the spool must overcome friction to rotate in the unwinding direction, it ensures that tension is maintained in the belt 218 during the unwinding operation. In some implementations, when the one-way bearing 604A is disengaged, the ring gear 210 and bevel gear 208 rotate with the spool 212.

[0041] FIGS. 7A and 7B illustrate a manual crane showing an alternative implementation of a belt drive mechanism. The crane 700 can include a boom 704 and a load block 706 forming a belt-actuated mechanism 702. In this implementation, the belt-actuated lift mechanism 702 is the lifting device. The crane 700 can be operated using a self-reeling belt drive mechanism 701. In this implementation, the belt drive mechanism 701 is manually operated by a hand crank 708. This implementation can provide a user with mechanical advantage based on the diameter of the capstan and hand crank handle, and optionally, one or more block and tackle systems housed within the boom 704 (not shown). FIG. 7B shows an enlarged view of the belt drive mechanism 701, with various structural components removed for simplicity. Similar to the belt drive mechanism 101, the capstan 710, belt 712, spool 714, and idler shaft 716 are shown.

[0042] In some implementations, multiple belt drive mechanisms 101, or differently configured belt actuated mechanisms 102, may be provided to accommodate bidirectional application of power (e.g., powered extension / retraction). For example, pairs of block and tackle systems may be coupled to each other and configured to operate in opposition to each other (e.g., one belt is paid out while the other belt is retracted), providing both powered extension and retraction of the linear actuator.

[0043] Although illustrated as having a rectangular cross-section throughout, belt 218 may be of any suitable shape. For example, belt 218 may have a square, triangular, trapezoidal, or any combination thereof. In some implementations, one portion of belt 218 may have a trapezoidal cross-section, while another portion may be triangular. The disclosure is not limited in this respect. Additionally, belt 218 may be constructed from any suitable material, such as braided steel, Kevlar, rubber, leather, or combinations thereof.

[0044] Although the winding mechanism is shown with an angled idler shaft and spool secured to the side of the belt drive, in some implementations the spool can be above or below the belt drive. In some implementations, the idler shaft can protrude from the rear of the belt drive and rotate a spool away from the belt drive.

[0045] The foregoing description has been provided in the context of one or more specific implementations. Various modifications, changes, and substitutions of the disclosed implementations can be made without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to only the implementations described or illustrated, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Claims

1. A self-rewinding belt drive mechanism comprising: a capstan configured to retract or unreel a belt from a belt-driven system; an idler shaft connected to the capstan via the belt, wherein the idler shaft is configured to rotate in a retracting direction when the capstan rotates in a direction to retract the belt, and to rotate in a paying-out direction when the capstan rotates in a direction to pay-out the belt, and the idler shaft is a first end configured to receive one or more wraps of the belt; a second end coupled to the first one-way locking bearing; a first gear coupled to the first one-way locking bearing, wherein the first one-way locking bearing engages when the idler shaft rotates in the retraction direction to rotate the first gear with the rotating idler shaft, and the first one-way locking bearing disengages when the idler shaft rotates in the payout direction to allow relative rotation between the first gear and the idler shaft; and the self-rewinding belt drive mechanism further comprises: a spool configured to receive or pay out a portion of the belt, the spool comprising: an outer hub configured to rotate and wind the portion of the belt around or unwind the portion of the belt from the hub, the spool further comprising: a second gear frictionally engaged with the outer hub, the second gear configured to be driven by the first gear such that the first gear drives the second gear, causing the outer hub to rotate in a direction to reel in the portion of the belt when the idler shaft rotates in the retraction direction.

2. 2. The belt drive mechanism of claim 1, wherein the spool includes an inner hub connected to a central shaft via a second one-way locking bearing, the second one-way locking bearing allowing the inner hub to rotate relative to the central shaft when the outer hub rotates in a direction to wind the certain portion of the belt, the second one-way locking bearing preventing rotation between the inner hub and the central shaft when the outer hub rotates in a direction to unwind the certain portion of the belt, and the inner hub is frictionally engaged with the outer hub such that the outer hub rotates relative to the inner hub, overcoming frictional forces between the inner hub and the outer hub, when the inner hub rotates in a direction to unwind the certain portion of the belt.

3. 2. The belt drive mechanism of claim 1, wherein the first gear is a bevel gear and the second gear is a ring gear.

4. 2. The belt drive mechanism of claim 1, wherein the second gear is configured to overdrive the outer hub and rotates at least 1.5% faster than the outer hub.

5. 2. The belt drive mechanism of claim 1, wherein the belt passes through the belt actuated system and returns to the belt drive mechanism such that both a first end and a second end of the belt are within the belt drive mechanism, and retraction and unretraction of the belt actuates the belt actuated system.

6. 6. The belt drive mechanism of claim 5, wherein the belt actuated system includes a block and tackle that expands or contracts as the belt is retracted from or paid out of the belt actuated system.

7. 6. The belt drive of claim 5, wherein at least one end of the belt is electrically connected to a circuit within the belt drive, the circuit measuring at least one electrical parameter associated with the belt.

8. 10. The belt drive mechanism of claim 1, further comprising an encoder wheel having an outer surface with ribs, said ribs engaging notches in said belt, said encoder wheel shaft being connected to an encoder.

9. A self-rewinding belt drive mechanism comprising: a capstan configured to retract or unreel a belt from a belt-driven system; an idler shaft connected to the capstan via the belt, wherein the idler shaft is configured to rotate in a retracting direction when the capstan rotates in a direction to retract the belt, and to rotate in a paying-out direction when the capstan rotates in a direction to pay-out the belt, and the idler shaft is a first end configured to receive one or more wraps of the belt; a second end coupled to the first one-way locking bearing; a first gear coupled to the first one-way locking bearing, wherein the first one-way locking bearing engages when the idler shaft rotates in the retraction direction to rotate the first gear with the rotating idler shaft, and the first one-way locking bearing disengages when the idler shaft rotates in the payout direction to allow relative rotation between the first gear and the idler shaft; and the self-rewinding belt drive mechanism further comprises: a spool configured to receive or pay out a portion of the belt, the spool comprising: an outer hub configured to rotate and wind the portion of the belt around or unwind the portion of the belt from the hub, the spool further comprising:

1. A self-rewinding belt drive mechanism comprising: an inner hub connected to a central shaft via a second one-way locking bearing, the second one-way locking bearing allowing the inner hub to rotate relative to the central shaft when the outer hub rotates in a direction to reel in the portion of the belt; the second one-way locking bearing preventing rotation between the inner hub and the central shaft when the outer hub rotates in a direction to unwind the portion of the belt; and the inner hub frictionally engaged with the outer hub such that the outer hub rotates relative to the inner hub, overcoming frictional forces between the inner hub and the outer hub, when the inner hub rotates in a direction to unwind the portion of the belt.

10. 10. The belt drive mechanism of claim 9, wherein the spool includes a second gear frictionally engaged with the outer hub, the second gear configured to be driven by the first gear such that the first gear drives the second gear, causing the outer hub to rotate in a direction to reel in the portion of the belt when the idler shaft rotates in the retraction direction.

11. 11. The belt drive mechanism of claim 10, wherein the first gear is a bevel gear and the second gear is a ring gear.

12. 11. The belt drive mechanism of claim 10, wherein the second gear is configured to overdrive the outer hub and rotates at least 1.5% faster than the outer hub.

13. 10. The belt drive mechanism of claim 9, wherein the belt passes through the belt actuated system and returns to the belt drive mechanism such that both the first end and the second end of the belt are within the belt drive mechanism, and retraction and unretraction of the belt actuates the belt actuated system.

14. 14. The belt drive mechanism of claim 13, wherein the belt actuated system includes a block and tackle that expands or contracts as the belt is retracted from or paid out of the belt actuated system.

15. 14. The belt drive of claim 13, wherein at least one end of the belt is electrically connected to a circuit within the belt drive, the circuit measuring at least one electrical parameter associated with the belt.

16. 10. The belt drive mechanism of claim 9, further comprising an encoder wheel having an outer surface with ribs, the ribs engaging notches in the belt, the shaft of the encoder wheel being connected to an encoder.

17. A self-rewinding belt drive mechanism comprising: a capstan configured to retract or unreel a belt from a belt-driven system; an idler shaft connected to the capstan via the belt, wherein the idler shaft is configured to rotate in a retracting direction when the capstan rotates in a direction to retract the belt, and to rotate in a paying-out direction when the capstan rotates in a direction to pay-out the belt, and the idler shaft is a first end configured to receive one or more wraps of the belt; a second end coupled to the first one-way locking bearing; a first gear coupled to the first one-way locking bearing, wherein the first one-way locking bearing engages when the idler shaft rotates in the retraction direction to rotate the first gear with the rotating idler shaft, and the first one-way locking bearing disengages when the idler shaft rotates in the payout direction to allow relative rotation between the first gear and the idler shaft; and the self-rewinding belt drive mechanism further comprises: a spool configured to receive or pay out a portion of the belt, the spool comprising: an outer hub configured to rotate and wind the portion of the belt around or unwind the portion of the belt from the hub, the spool further comprising: an inner hub connected to a central shaft via a second one-way locking bearing, the second one-way locking bearing allowing the inner hub to rotate relative to the central shaft when the outer hub rotates in a direction to wind the certain portion of the belt, the second one-way locking bearing preventing rotation between the inner hub and the central shaft when the outer hub rotates in a direction to unwind the certain portion of the belt, the inner hub frictionally engaged with the outer hub such that the outer hub rotates relative to the inner hub by overcoming a frictional force between the inner hub and the outer hub when the spool rotates in a direction to unwind the certain portion of the belt, a second gear frictionally engaged with the outer hub, the second gear configured to be driven by the first gear such that the first gear drives the second gear, causing the outer hub to rotate in a direction to reel in the portion of the belt when the idler shaft rotates in the retraction direction.

18. 18. The belt drive mechanism of claim 17, wherein the first gear is a bevel gear and the second gear is a ring gear, the ring gear configured to overdrive the outer hub and rotate at least 1.5% faster than the outer hub.

19. 18. The belt drive mechanism of claim 17, further comprising an encoder wheel having an outer surface with ribs, the ribs engaging notches in the belt, the shaft of the encoder wheel being connected to an encoder.

20. 18. The belt drive mechanism of claim 17, wherein the belt passes through the belt actuated system and returns to the belt drive mechanism such that a first end and a second end of the belt are both within the belt drive mechanism, and retraction and unretraction of the belt actuates the belt actuated system.

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