Patent Application
20220254584
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.
Features and advantages of the disclosed technology will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosed technology; and, wherein:
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.
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 to
The shaft 102 and the housing 104 shown in
With reference to
The lower spring mount 112 includes an annular side wall 114. The annular side wall 114 comprises a raised cam surface 116 on an exterior surface of the annular side wall 114. The raised cam surface 116 is operable to facilitate activation of the rotational over travel protection device 100 to provide over rotation protection, as will be described in more detail below. The annular side wall 114 further comprises a pawl 118 on an interior surface of the annular side wall 114. The pawl 118 is sized and configured to interface with the shaft 102 to cause rotation of the triggering device 115 when the protrusion 118 engages with the shaft 102.
The rotational over travel protection device 100 further comprises a washer 120, snap ring 122, and cable management member 124 that are disposed in and supported by the housing 104. The housing 104 is closed via an O-ring 126 and a cover 128. The cover 128 can be connected to the housing 104 and can compress the O-ring 126 via fasteners 130.
Referring now to
Because the pawl 118 of the triggering device 115 is located 180 degrees from the zero position of the protrusion 132, the shaft 102 can rotate relative to the housing 104 substantially or approximately 180 degrees in each direction prior the protrusion 132 of the shaft 102 engaging with the pawl 118 of the triggering device 115. In other words, the shaft 102 rotates without engaging the triggering device 115 over at least some rotational range or degrees. Upon further and sufficient rotation of the shaft 102, the protrusion 132 of the shaft can engage the pawl 118, wherein the triggering device 115 is caused to simultaneously rotate with the shaft 102 through an additional range of rotation. In other words, the triggering device 115 rotates with the shaft 102 over at least some of the rotational range or degrees of the shaft 102 relative to the housing 104. Rotation of the triggering device 115 with the shaft 102 to one or more pre-determined rotational degrees from its neutral position functions to facilitate the arrest of further rotation of the shaft 102, thus preventing over rotation of the shaft 102 relative to the housing 104. As indicated herein, over rotation protection can be for the purpose of protecting over rotation of the cable 10 to prevent damage or degraded performance of the cable 10. 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 shaft 102 so 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 shaft 102 rotates relative to the housing 104, the protrusion 118 also rotates from the zero position. In this example, the shaft 102 can rotate in either direction from the zero position. The shaft 102 can be rotated by a motor, for example. The motor controlling the speed and position of the rotation of the shaft 102 can 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 switches 134a, 134b and a second pair of rotational limit switches 136a, 136b. Each of the first pair of rotational limit switches 134a, 134b comprises a cam follower (or cam follower surface) (see cam followers 135a, 135b, respectively) that can be sized and configured to activate the first pair of rotational limit switches 134a, 134b. Similarly, each of the second pair of rotational limit switches 136a, 136b comprises a cam follower (see cam followers 137a, 137b, respectively) sized and configured to activate the second pair of rotational limit switches 136a, 136b.
The first and second pairs of rotational limit switches 134a, 134b, 136a, 136b are operable to limit rotation of the shaft 102 relative to the housing 104 to prevent over travel of the shaft 102 relative to the housing 104. This prevents over rotation of a cable extending from the shaft 102 to the housing 104 (or over rotation of one or more components supported and driven by the shaft 102). Activation of the switches 134a, 134b, 136a, 136b can 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 switches 134a, 134b, 136a, 136b provide primary and redundant mechanisms to ensure over travel of the shaft 102 relative to the housing 104 is prevented. For example, the first pair of rotational limit switches 134a 134b can include an initial limit switch 134a (or a first limit switch in the first pair of limit switches) and a final limit switch 134b (or a second switch in the first pair of limit switches). The initial limit switch 134a can be operable to send overriding control instructions to a motor to stop rotation of the shaft 102 relative to the housing 104, for example. In the event that the initial limit switch 134a fails to stop the relative rotation of the shaft 102 and the housing 104, the final limit switch 134b can be operable to cut power to the motor to ensure no further rotation of the shaft 102 relative to the housing 104, for example.
Likewise, the second rotational limit switches 136a 136b can include an initial limit switch 136a (a first limit switch in the second pair of limit switches) and a final limit switch 136b (a second limit switch in the second pair of limit switches). The initial limit switch 136a can be operable to send control instructions to a motor to stop rotation of the shaft 102 relative to the housing 104, for example. In the event that the initial limit switch 136a fails to stop the relative rotation of the shaft 102 and the housing 104, the final limit switch 136b can be operable to cut power to the motor to ensure no further rotation of the shaft 102 relative to the housing 104, 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 switches 134a, 134b, 136a, 136b, other examples can exclude the redundancy and only include one of the first pair of rotational limit switches 134a, 134b and one of the second pair of rotational limit switches 136a, 136b, depending on the requirements for a given application. In other examples, the pairs of rotational limit switches 134a, 134b, 136a, 136b, can be used for different purposes. For example the initial limit switches 134a, 136a can be used to limit a rotational speed of the shaft 102 relative to the housing 104, and the final limit switches 134b, 136b can arrest any further rotation of the shaft 102 relative to the housing 104.
Advantageously, the triggering device 115, the protrusion 118 of the shaft 102, and the first and second rotational limit switches 134a, 134b, 136a, 136b can all be supported in the same plane. In this example, the plane can be defined by the rotational plane in which the triggering device 115 rotates. 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 device 100 allows for rotation of the shaft 102 relative 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 in
In this example, when the protrusion 132 of the shaft 102 reaches 270 degrees, the cam surface 116 of the triggering device 115 engages with the cam follower 137a of the initial rotational limit switch 136a. This activates the initial rotational limit switch 136a to prevent further rotation of the shaft 102 relative to the housing 104, such as by sending an overriding control instruction to a motor to stop further clockwise rotation of the shaft 102 relative to the housing 104.
While not explicitly shown, the shaft 102 can also rotate counter-clockwise from the zero position, such that the protrusion 132 of the shaft 102 engages with the pawl 118 to rotate the triggering device 115 until the cam surface 116 engages the cam follower 135a of the initial rotational limit switch 134a (also located at 270 degrees in this example) to prevent further rotation in the counter-clockwise direction.
When the shaft 102 returns back to an angle that is less than 180 degrees from the zero position, the triggering device 115 disengages from the protrusion 132 of the shaft 102 and is biased back to its neutral position. The shaft 102 can be further rotated to the position in
In this example using redundant rotational limit switches, in the event that the activation of either of the initial limit switches 134a, 136a fails, further rotation of the shaft 102 relative to the housing 104 in the respective directions to engage these, can trigger the activation of the final limit switches 134b, 136b. As shown in
Likewise, though not explicitly shown, if the protrusion 132 has rotated counter-clockwise past 270 degrees from the zero position, assuming failure of the rotational limit switch 134a, the final rotational limit switch 134b (in this example being located at 300 degrees) can be activated via the cam surface 116 of the triggering device 115.
Thus, in the above example, the rotational over travel protection device 100 can prevent the over rotation of a cable extending from the shaft 102 to the housing 104 (and/or over rotation of one or more components supported and driven by the shaft 102). The rotational over travel protection device 100 can 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 switches 134a, 134b can be offset in a different plane from the final rotational limit switches 136a, 136b, and the triggering device 115 can rotate on an inclined plane or screw. This can potentially allow for greater than 360 degree rotation of the shaft 102 relative to the housing 104 if mechanical constraints of the cable (and/or supported components) allow.
Further, while the triggering device 115 and the rotational limit switches 134a, 136a are shown to limit rotation of the shaft 102 relative to the housing 104 to 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 shaft 102 relative 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 to
The relative size of the first gear 440 with the second gear 461, and the placement of the stops 462, 464 and/or the first and second rotational limit switches 466, 468 can be determined based on the desired limits of rotation of the shaft 402 from a zero position. The gear reduction between the first gear 440 and second gear 461 can allow for rotation of the shaft 402 of greater than 180 degrees in each direction from a zero position. Further, in the example shown in
Reference was made to the examples illustrated in the drawings and specific language was used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. Alterations and further modifications of the features illustrated herein and additional applications of the examples as illustrated herein are to be considered within the scope of the description.
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.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the preceding description, numerous specific details were provided, such as examples of various configurations to provide a thorough understanding of examples of the described technology. It will be recognized, however, that the technology may be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the technology.
Although the subject matter has been described in language specific to structural features and/or operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. Numerous modifications and alternative arrangements may be devised without departing from the spirit and scope of the described technology.
This invention was made with government support under contract No. W15QKN-20-9-1002 awarded by the US Army Contracting Command. The government has certain rights in the invention.
