Rotational over travel protection for preventing over rotation of an object

A rotational over travel protection device for preventing over rotation of at least one of a cable, or a component operable with the rotational over travel protection device is provided. The device includes a housing, a rotatable shaft connected to the housing that can rotate relative to the house, and a triggering device supported in the housing and rotatable with the rotatable shaft. The device also includes a first and second rotational limit switch disposed in the housing. The switches are operable to be activated by the triggering device to arrest rotation of the rotatable shaft upon relative rotation of the rotatable shaft and the housing either a first or second rotation direction, respectively, at least 180 degrees from a zero position.

BACKGROUND

In many applications, electrical or communication signals are passed through components that have moving parts. For example, power and/or data transfer in some applications needs to travel from a stationary part to a rotating part within an assembly. Accordingly, there are solutions that provide for a connector to transmit electrical power and/or data from a stationary part to a moving part, such as a rotating part, within the assembly. Such connectors can be referred to as slip rings, rotary electrical interfaces, electrical rotatory joints, or the like. These connectors allow for both the relative rotation of parts as well as the transmission of electrical power and/or data.

However, the use of such connectors results in line loss in the power or data that is transmitted through these connectors. In some applications, such line loss is unacceptable for the functionality of the system. In such situations, instead of using a connector, a cable can be used between moving parts which twists along with the relative rotation between parts of an assembly. Of course, a cable has a limit to how much it can twist or rotate without being damaged. Thus, when using a cable between moving parts, it is important that the cable is not twisted past its mechanical limits. In addition, the rotation of the parts that rotate relative to one another should be limited so as to prevent any components that are operable with the relative rotating parts from rotating into fixed objects or other components within the assembly. Thus, there is a need to provide a way to prevent rotational over travel of a cable while still allowing the moving parts to rotate sufficiently in accordance with the needs of a given application.

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the exemplary embodiments is thereby intended.

DETAILED DESCRIPTION

An initial overview of the inventive concepts are provided below and then specific examples are described in further detail later. This initial summary is intended to aid readers in understanding the examples more quickly, but is not intended to identify key features or essential features of the examples, nor is it intended to limit the scope of the claimed subject matter.

In one example, the present disclosure sets forth a rotational over travel protection device for preventing over rotation of an object, such as a cable, supported by the rotational over travel protection device, as well as preventing any components operable with (e.g., supported by, driven by) the shaft from over rotating such that they rotate into other components within the assembly incorporating the rotational over travel protection device, or into any fixed objects in the vicinity of the assembly. The rotational over travel protection device can comprise a housing and rotatable shaft connected to the housing. The rotatable shaft and the housing can be operable to rotate relative to one another. The rotational over travel protection device can further comprise a triggering device supported in the housing. The triggering device can be rotatable with the rotatable shaft through at least some rotational degrees of the rotatable shaft.

The rotational over travel protection device can further comprise a first rotational limit switch disposed in the housing. The first rotation limit switch can be operable to be activated by the triggering device to arrest rotation of the rotatable shaft upon relative rotation of the rotatable shaft and the housing in a first rotation direction greater than 180 degrees from a zero position. The rotational over travel protection device can also comprise a second rotational limit switch disposed in the housing. The second rotational limit switch can be operable to be activated by the triggering device to arrest rotation of the rotatable shaft upon relative rotation of the rotatable shaft and the housing in a second rotation direction greater than 180 degrees from the zero position where the second rotation direction is opposite the first rotation direction.

In one example, the first and second rotational limit switches and the triggering device are supported in a common plane. The triggering device can comprise a pawl operable to engage with a protrusion disposed on the rotatable shaft. The protrusion can engage the pawl after the shaft rotates substantially 180 degrees from the zero position in both the first rotation direction and the second rotation direction.

In some examples, the rotational over travel protection device can comprise a biasing member that biases (e.g., returns) the pawl in a neutral position when the pawl is not engaged with the protrusion. The biasing member can be a rotational spring interfaced with the triggering device.

In some examples, the triggering device can comprise a cam surface, and the first and second rotational limit switches can each comprise a cam follower. The triggering device can activate the first and second rotational limit switches upon the cam surface engaging the cam follower.

In some examples, the shaft can be associated with a first gear, and the triggering device comprise a second gear interfacing with the first gear. The triggering device can comprise first and second stops that interface with the first and second rotational limit switches. The first and second rotational limit switches can comprise face plungers.

In another example, a rotational over travel protection device for preventing over rotation of an object, such as a cable and/or any components operable with (e.g., supported by, driven by) the rotational over travel protection device is provided. The rotational over travel protection device can comprise a housing and a rotatable shaft connected to the housing. The rotatable shaft and the housing can be operable to rotate relative to one another. The rotational over travel protection device can also comprise a triggering device that is interfaced to the rotatable shaft and is configured to rotate in a rotational plane.

The rotational over travel protection device can comprise a first rotational limit switch disposed in the housing. The first rotational limit switch being can be disposed coplanar with the rotational plane of the triggering device. The rotational over travel protection device can also comprise a second rotational limit switch disposed in the housing. The second rotational limit switch can also be disposed coplanar with the rotational plane of the triggering device.

The triggering device can activate the first rotational limit switch to arrest rotation of the rotatable shaft upon a rotation of the rotatable shaft of greater than 180 degrees in a first rotation direction from a zero position relative to the housing. The triggering device can also activate the second rotational limit switch to arrest rotation of the rotatable shaft upon a rotation of the rotatable shaft of greater than 180 degrees in a second rotation direction from the zero position relative to the housing, where the second rotation direction is opposite the first rotation direction.

In some examples, the triggering device can comprise a pawl operable to engage with a protrusion disposed on the rotatable shaft. The protrusion can engage the pawl after the shaft rotates 180 degrees from the zero position in both the first rotation direction and the second rotation direction. Upon engagement of the protrusion of the shaft with the pawl of the triggering device, the triggering device rotates with the shaft.

In some examples, the rotational over travel protection device can comprise a biasing member that biases the pawl in a neutral position when the pawl is not engaged with the protrusion. The biasing member can be a rotational spring interfaced with the triggering device and the housing.

In some examples, the triggering device can comprise a cam surface, and the first and second rotational limit switches can each comprise a cam follower. The triggering device can activate the first and second rotational limit switches with the cam surface engaging the cam follower.

In some examples, the shaft can be associated (e.g., integrated) with a first gear, and the triggering device can comprise a second gear interfacing with the first gear. The triggering device can comprise first and second stops that interface with the first and second rotational limit switches, which in some examples, can comprise face plungers.

In another example, a method for providing rotational over travel protection for preventing over rotation of an object, such as a cable and/or any components operable with (e.g., supported by, driven by) the rotational over travel protection device is provided. The method can comprise rotating a shaft relative to a housing in a first direction at least 180 degrees from a zero position, rotating a triggering device to activate a first rotational limit switch to arrest further rotation of the shaft relative to the housing in the first direction at a predetermined rotational position, rotating the shaft relative to the housing in a second direction at least 180 degrees from the zero position and rotating the triggering device to activate a second rotational limit switch to arrest further rotation of the shaft relative to the housing in the second direction at a predetermined rotational position, wherein the triggering device, the first rotational limit switch, and the second rotational limit switch are supported in a common plane.

In some examples, the first and second rotational limit switches are activated by a cam follower on the first and second rotational limit switches interfacing with a cam surface of the triggering device.

In some examples, the shaft is associated with a first gear, and the triggering device is associated with a second gear interfacing with the first gear.

To further describe the present technology, examples are now provided with reference to the figures. With reference toFIG.1, a rotational over travel protection device100is provided. The rotational over travel protection device100is operable to prevent the over rotation of an object, such as an object supported by, about, within, or otherwise operable with the rotational over travel protection device100. In one example, the object can comprise a cable10, such as a fiber optic cable, supported by the rotational over travel protection device10. In one example, the cable10can be supported via a connector or connector assembly supported within the rotational over travel protection device100. The connector or connector assembly can be supported by the housing104, wherein the cable10is routed through the shaft102and connected to the connector or connector assembly via a mating connector on the cable10. In another example, the object can comprise one or more components operable with (e.g., supported by, driven by) the rotational over travel protection device100(e.g., the shaft as discussed below), wherein the rotational over travel protection device100can operate to prevent such components from rotating into any fixed object or into any other objects that might be in the vicinity of the rotational over travel protection device100, or into any other components within an assembly incorporating the rotational over travel protection device100. The rotational over travel protection device100comprises two components that rotate relative to one another and that support the cable10and/or rotating components. The cable10extends from one component to the other which causes the cable10to twist with the rotation of the two components. As shown inFIG.1, the rotational over travel protection device100comprises components that rotate relative to one another in the form of a shaft102that is rotatable relative to a housing104. Although not shown, one or more components can be coupled or otherwise supported by the shaft102, so as to be driven (i.e., rotated) by the shaft102upon actuated rotation of the shaft102.

The shaft102and the housing104shown inFIG.1are exemplary of two parts that rotate relative to one another as part of the rotational over travel protection device100. However, those skilled in the art will recognize other rotatable parts that can be used as part of the rotational over travel protection device100, and therefore the shaft102and housing104are not intended to be limiting in any way. For example, the rotational over travel protection device100can be used to limit rotation of a rotating pedestal, a turn table, a rotatable display, or any others. Regardless of the form, the shaft102is rotatable relative to the housing104which causes twist in the cable10, and any components driven by the shaft102to be rotated.

With reference toFIG.2, the shaft102interfaces with the housing104and is rotatable relative to the housing104. Within the housing104is an upper spring mount106, a rotational spring108, and a lower spring mount112. The upper spring mount106, rotational spring108, and lower spring mount112collectively defining a triggering device115operable to activate over rotation protection, as will be described in more detail below. The upper spring mount106and lower spring mount112together house the rotational spring108. The rotational spring108comprises one or more protruding ends110that are configured to interface with the housing104to secure a position of the rotational spring108. The interfacing of the rotational spring108with the housing104is provided to bias the triggering device115into a neutral position. The rotational spring108is just one example of a biasing member used to bias the triggering device115into a neutral position. Those skilled in the art will recognize that other biasing members or mechanisms can also be used, such as other types of springs.

The lower spring mount112includes an annular side wall114. The annular side wall114comprises a raised cam surface116on an exterior surface of the annular side wall114. The raised cam surface116is operable to facilitate activation of the rotational over travel protection device100to provide over rotation protection, as will be described in more detail below. The annular side wall114further comprises a pawl118on an interior surface of the annular side wall114. The pawl118is sized and configured to interface with the shaft102to cause rotation of the triggering device115when the protrusion118engages with the shaft102.

The rotational over travel protection device100further comprises a washer120, snap ring122, and cable management member124that are disposed in and supported by the housing104. The housing104is closed via an O-ring126and a cover128. The cover128can be connected to the housing104and can compress the O-ring126via fasteners130.

Referring now toFIGS.3A-3C, described is the operation of the rotational over travel protection device ofFIGS.1-2to provide over rotation protection, and a method for providing rotational over travel protection for preventing over rotation of a cable and/or any components being driven that are associated with the rotational over travel protection device. The shaft102comprises a protrusion132disposed on an outer surface of the shaft102. InFIG.3A, the protrusion132and the shaft102are shown in a zero position or a reference position relative to the housing104. In the zero or reference position, a cable (such as cable10shown inFIG.1) that extends from the housing104to the shaft102is in a neutral or an untwisted state. Likewise, inFIG.3A, the triggering device115is biased by a biasing member (such as rotational spring108shown inFIG.2) in a neutral position. In this example, the neutral position of the pawl118of the triggering device115is disposed approximately 180 degrees from the protrusion132of the shaft102at the zero position. Or in other words, the neutral position of the pawl118of the triggering device115is located on an opposite side of the shaft102from the protrusion132when the shaft102is in the zero position.

Because the pawl118of the triggering device115is located 180 degrees from the zero position of the protrusion132, the shaft102can rotate relative to the housing104substantially or approximately 180 degrees in each direction prior the protrusion132of the shaft102engaging with the pawl118of the triggering device115. In other words, the shaft102rotates without engaging the triggering device115over at least some rotational range or degrees. Upon further and sufficient rotation of the shaft102, the protrusion132of the shaft can engage the pawl118, wherein the triggering device115is caused to simultaneously rotate with the shaft102through an additional range of rotation. In other words, the triggering device115rotates with the shaft102over at least some of the rotational range or degrees of the shaft102relative to the housing104. Rotation of the triggering device115with the shaft102to one or more pre-determined rotational degrees from its neutral position functions to facilitate the arrest of further rotation of the shaft102, thus preventing over rotation of the shaft102relative to the housing104. As indicated herein, over rotation protection can be for the purpose of protecting over rotation of the cable10to prevent damage or degraded performance of the cable10. In another aspect, this can be for the purpose of limiting the rotation of one or more components coupled or otherwise supported and driven by the shaft102so that the one or more components are prevented from rotating into other fixed components in an assembly incorporating the rotational over travel protection device, or to one or more components in the vicinity of the assembly. Preventing over rotation of a cable is discussed primarily herein, but this merely to illustrate one exemplary application where over rotation between two structures is to be limited.

When the shaft102rotates relative to the housing104, the protrusion118also rotates from the zero position. In this example, the shaft102can rotate in either direction from the zero position. The shaft102can be rotated by a motor, for example. The motor controlling the speed and position of the rotation of the shaft102can be operated by a controller based on a user input, control instructions such as software, or the like.

The rotational over travel protection device further comprises a first pair of rotational limit switches134a,134band a second pair of rotational limit switches136a,136b. Each of the first pair of rotational limit switches134a,134bcomprises a cam follower (or cam follower surface) (see cam followers135a,135b, respectively) that can be sized and configured to activate the first pair of rotational limit switches134a,134b. Similarly, each of the second pair of rotational limit switches136a,136bcomprises a cam follower (see cam followers137a,137b, respectively) sized and configured to activate the second pair of rotational limit switches136a,136b.

The first and second pairs of rotational limit switches134a,134b,136a,136bare operable to limit rotation of the shaft102relative to the housing104to prevent over travel of the shaft102relative to the housing104. This prevents over rotation of a cable extending from the shaft102to the housing104(or over rotation of one or more components supported and driven by the shaft102). Activation of the switches134a,134b,136a,136bcan limit rotation by sending overriding control signals or instructions to a motor to stop or reverse rotation, by cutting power to a motor, by applying a brake, or through other control, electronic, or mechanical techniques.

In this example, the first and second pairs of rotational limit switches134a,134b,136a,136bprovide primary and redundant mechanisms to ensure over travel of the shaft102relative to the housing104is prevented. For example, the first pair of rotational limit switches134a134bcan include an initial limit switch134a(or a first limit switch in the first pair of limit switches) and a final limit switch134b(or a second switch in the first pair of limit switches). The initial limit switch134acan be operable to send overriding control instructions to a motor to stop rotation of the shaft102relative to the housing104, for example. In the event that the initial limit switch134afails to stop the relative rotation of the shaft102and the housing104, the final limit switch134bcan be operable to cut power to the motor to ensure no further rotation of the shaft102relative to the housing104, for example.

Likewise, the second rotational limit switches136a136bcan include an initial limit switch136a(a first limit switch in the second pair of limit switches) and a final limit switch136b(a second limit switch in the second pair of limit switches). The initial limit switch136acan be operable to send control instructions to a motor to stop rotation of the shaft102relative to the housing104, for example. In the event that the initial limit switch136afails to stop the relative rotation of the shaft102and the housing104, the final limit switch136bcan be operable to cut power to the motor to ensure no further rotation of the shaft102relative to the housing104, for example. The redundant final or second rotational limit switch in each of the first and second pairs of rotational limit switches can be referred to as a backup rotational limit switch.

While the above example shows the two pairs of rotational limit switches134a,134b,136a,136b, other examples can exclude the redundancy and only include one of the first pair of rotational limit switches134a,134band one of the second pair of rotational limit switches136a,136b, depending on the requirements for a given application. In other examples, the pairs of rotational limit switches134a,134b,136a,136b, can be used for different purposes. For example the initial limit switches134a,136acan be used to limit a rotational speed of the shaft102relative to the housing104, and the final limit switches134b,136bcan arrest any further rotation of the shaft102relative to the housing104.

Advantageously, the triggering device115, the protrusion118of the shaft102, and the first and second rotational limit switches134a,134b,136a,136bcan all be supported in the same plane. In this example, the plane can be defined by the rotational plane in which the triggering device115rotates. This allows the packaging and/or size of the rotational over travel protection device to remain small. At the same time, the rotational over travel protection device100allows for rotation of the shaft102relative to the housing to be greater than 180 degrees in each direction from the zero position. Thus, the rotational over travel protection device can be both compact and allow a wide range of rotational movement.

As shown inFIG.3B, the shaft102can rotate relative to the housing104. In this example, the shaft102is shown to have rotated clockwise 270 degrees from the zero position (as shown inFIG.3A). As is shown with this exemplary number of degrees of rotation of the shaft102, the protrusion132of the shaft102is engaged with the pawl118of the triggering device115, wherein the triggering device115is caused to rotate with the shaft102from its neutral position as shown inFIG.3A. That is, the protrusion132of the shaft102rotates independently until it has rotated 180 degrees, at which point it engages with the pawl118of the triggering device115. The shaft102and triggering device115then rotate together as the shaft102rotates past 180 degrees from the zero position.

In this example, when the protrusion132of the shaft102reaches 270 degrees, the cam surface116of the triggering device115engages with the cam follower137aof the initial rotational limit switch136a. This activates the initial rotational limit switch136ato prevent further rotation of the shaft102relative to the housing104, such as by sending an overriding control instruction to a motor to stop further clockwise rotation of the shaft102relative to the housing104.

While not explicitly shown, the shaft102can also rotate counter-clockwise from the zero position, such that the protrusion132of the shaft102engages with the pawl118to rotate the triggering device115until the cam surface116engages the cam follower135aof the initial rotational limit switch134a(also located at 270 degrees in this example) to prevent further rotation in the counter-clockwise direction.

When the shaft102returns back to an angle that is less than 180 degrees from the zero position, the triggering device115disengages from the protrusion132of the shaft102and is biased back to its neutral position. The shaft102can be further rotated to the position inFIG.3Ato place the protrusion132of the shaft102in the zero position with the pawl118again oriented 180 degrees from the protrusion132of the shaft102. The triggering device115is biased to this position via a biasing member of the triggering device115(such as via the rotational spring108shown inFIG.2).

In this example using redundant rotational limit switches, in the event that the activation of either of the initial limit switches134a,136afails, further rotation of the shaft102relative to the housing104in the respective directions to engage these, can trigger the activation of the final limit switches134b,136b. As shown inFIG.3C, assuming the failure of the first or initial rotational limit switch136a, the protrusion132has rotated clockwise past 270 degrees from the zero position to a position approximately 300 degrees. With the triggering device115simultaneously moving with the rotating shaft102due to the interface between the protrusion132and the pawl118, further rotation in the same direction causes the cam surface116of the triggering device115to engage with the cam follower137bof the final rotational limit switch136bto activate the final rotational limit switch136b. In one example, activation of the final rotational limit switch136bcan result in electrical power being cut off to the motor, and/or can cause a brake to be applied to the shaft102, such that further rotation of the shaft102in the clockwise direction is prevented.

Likewise, though not explicitly shown, if the protrusion132has rotated counter-clockwise past 270 degrees from the zero position, assuming failure of the rotational limit switch134a, the final rotational limit switch134b(in this example being located at 300 degrees) can be activated via the cam surface116of the triggering device115.

Thus, in the above example, the rotational over travel protection device100can prevent the over rotation of a cable extending from the shaft102to the housing104(and/or over rotation of one or more components supported and driven by the shaft102). The rotational over travel protection device100can further be compact while simultaneously allowing rotation greater than 180 degrees in each direction from a zero position.

Other variations are also contemplated. For example, in applications where there are less significant space constraints, the initial rotational limit switches134a,134bcan be offset in a different plane from the final rotational limit switches136a,136b, and the triggering device115can rotate on an inclined plane or screw. This can potentially allow for greater than 360 degree rotation of the shaft102relative to the housing104if mechanical constraints of the cable (and/or supported components) allow.

Further, while the triggering device115and the rotational limit switches134a,136aare shown to limit rotation of the shaft102relative to the housing104to 270 degrees from a zero position, other rotational limits (i.e., other limited rotational degrees of rotation) larger or smaller than these can be set based on the needs of a given application, such as the mechanical limits of a particular cable, or due to space constraints of one or more components supported and driven by the shaft102relative to one or more other components, such as fixed components within an assembly.

Another example of a rotational over travel protection device is shown with respect toFIG.4. InFIG.4, a rotational over travel protection device400comprises a shaft402that is rotatable with respect to a housing404in a similar manner as discussed above. In this example, the shaft402is associated (e.g., integrated) with a first gear440. The first gear440can be sized and configured to interface with a triggering device460that comprises a second gear461. The triggering device460comprises a first stop462and a second stop464that are operable to activate a first rotation limit switch466and a second rotational limit switch468, respectively. In this example, the first and second stops462,464interface with respective plungers467,469disposed on the first and second rotation limit switches466,468. The plungers467,469activate the first and second rotational limit switches466,468, respectively, which can provide a similar function similar to the rotational limit switches discussed above to prevent further rotation of the shaft402relative to the housing404.

The relative size of the first gear440with the second gear461, and the placement of the stops462,464and/or the first and second rotational limit switches466,468can be determined based on the desired limits of rotation of the shaft402from a zero position. The gear reduction between the first gear440and second gear461can allow for rotation of the shaft402of greater than 180 degrees in each direction from a zero position. Further, in the example shown inFIG.4, the first gear440, the triggering device460, and the first and second rotational limit switches466,468are advantageously located on or otherwise supported in a common plane, allowing the rotational over travel protection device400to remain compact.

Although the disclosure may not expressly disclose that some embodiments or features described herein may be combined with other embodiments or features described herein, this disclosure should be read to describe any such combinations that would be practicable by one of ordinary skill in the art. The use of “or” in this disclosure should be understood to mean non-exclusive or, i.e., “and/or,” unless otherwise indicated herein.